U.S. Department of the Interior

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

OCS EIS/EA

BOEM 2017-051

Gulf of Mexico OCS 

Proposed Geological and Geophysical Activities

Western, Central, and Eastern Planning Areas

Final Programmatic Environmental Impact Statement

Volume II: Figures, Tables, Keyword Index, and Appendices A-D 

U.S. Department of the Interior

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

OCS EIS/EA

BOEM 2017-051

Gulf of Mexico OCS 

Proposed Geological and Geophysical Activities

Western, Central, and Eastern Planning Areas

Final Programmatic Environmental Impact Statement

Volume II: Figures, Tables, Keyword Index, and Appendices A-D 

Author

Bureau of Ocean Energy Management

Gulf of Mexico OCS Region

Prepared under

Contract No. GS-10F-0443M

and

Task Order No. M1PD00025

by

CSA Ocean Sciences Inc.

8502 SW Kansas Avenue

Stuart, Florida 34997

Published by 

New Orleans

August 2017

Gulf of Mexico G&G Activities Programmatic EIS iii

TABLE OF CONTENTS

Volume I

Page

EXECUTIVE SUMMARY ..................................................................................................................... vii

LIST OF FIGURES........................................................................................................................... xxixv

LIST OF TABLES........................................................................................................................... xxxivii

ABBREVIATIONS AND ACRONYMS ................................................................................................. lxi

CONVERSION CHART ..................................................................................................................... lxvii

1 INTRODUCTION ............................................................................................................................ 1-3

1.1 Proposed Action and Purpose and Need.............................................................................. 1-3

1.1.1 Proposed Action ........................................................................................................ 1-3

1.1.2 Purpose and Need..................................................................................................... 1-4 

1.1.3 Area of Interest .......................................................................................................... 1-6

1.2 Background............................................................................................................................ 1-7

1.2.1 History of G&G Environmental Review in the GOM.................................................. 1-8 

1.2.2 Petition for Authorization to Take Marine Mammals Incidental to Conducting 

Oil and Gas Exploration Activities in the Gulf of Mexico........................................... 1-9

1.2.3 Litigation Settlement................................................................................................ 1-10

1.2.3.1 Interim Mitigation Measures..................................................................... 1-11

1.2.3.2 Settlement Agreement Items for Analysis in This Programmatic EIS..... 1-13

1.2.3.3 Non-Duplicative Surveys and Lowest Practicable Source Levels 

Panels ...................................................................................................... 1-13

1.2.3.4 Monitoring Plan ........................................................................................ 1-14

1.2.3.5 Incentives for the Use of Noise Reduction Technology........................... 1-17

1.2.4 Environmental Baseline and the Deepwater Horizon Explosion, Oil Spill, and 

Response................................................................................................................. 1-17

1.2.5 Model Overview....................................................................................................... 1-18

1.2.6 Risk Assessment Framework.................................................................................. 1-24

1.3 Regulatory Framework ........................................................................................................ 1-26

1.3.1 Federal Laws, Regulations, and Agreements ......................................................... 1-26 

1.3.2 State Laws, Regulations, and Agreements............................................................. 1-27

1.4 Programmatic Approach to the NEPA Process................................................................... 1-27

1.5 Objectives and Scope.......................................................................................................... 1-29

2 ALTERNATIVES INCLUDING THE PROPOSED ACTION ........................................................... 2-3

2.1 Overview ................................................................................................................................ 2-3 

2.2 Additional Information Applicable to the Alternatives............................................................ 2-3
iv Table of Contents

2.3 Alternative A – Pre-Settlement (June 2013) Alternative........................................................ 2-7

2.3.1 Description................................................................................................................. 2-7 

2.3.2 Mitigation Measures .................................................................................................. 2-7 

2.3.3 Rationale.................................................................................................................... 2-8

2.4 Alternative B – Settlement Agreement Alternative................................................................ 2-8

2.4.1 Description................................................................................................................. 2-8 

2.4.2 Mitigation Measures .................................................................................................. 2-9 

2.4.3 Rationale.................................................................................................................. 2-10

2.5 Alternative C – Alternative A Plus Additional Mitigation Measures (Preferred 

Alternative)........................................................................................................................... 2-11

2.5.1 Description............................................................................................................... 2-11

2.5.2 Mitigation Measures ................................................................................................ 2-12

2.5.3 Rationale.................................................................................................................. 2-13

2.6 Alternative D – Alternative C Plus Marine Mammal Shutdowns ......................................... 2-13

2.6.1 Description............................................................................................................... 2-13

2.6.2 Mitigation Measures ................................................................................................ 2-13

2.6.3 Rationale.................................................................................................................. 2-15

2.7 Alternative E – Alternative C At Reduced Activity Levels ................................................... 2-15

2.7.1 Description............................................................................................................... 2-15

2.7.2 Mitigation Measures ................................................................................................ 2-15

2.7.3 Rationale.................................................................................................................. 2-17

2.8 Alternative F – Alternative C Plus Area Closures................................................................ 2-17

2.8.1 Description............................................................................................................... 2-17

2.8.2 Mitigation Measures ................................................................................................ 2-17

2.8.3 Rationale.................................................................................................................. 2-19

2.9 Alternative G – No New Activity Alternative ........................................................................ 2-20

2.9.1 Description............................................................................................................... 2-20

2.9.2 Mitigation Measures ................................................................................................ 2-22

2.9.3 Rationale.................................................................................................................. 2-22

2.10 Issues ................................................................................................................................... 2-22

2.10.1 Issues to be Analyzed ............................................................................................. 2-23

2.10.2 Issues Considered but Not Analyzed...................................................................... 2-24

2.11 Alternatives Considered but Not Carried Forward .............................................................. 2-25

2.11.1 Shutdown for All Marine Mammals Within the Level A Harassment Exclusion 

Zone......................................................................................................................... 2-26

2.11.2 Require Alternative Technology Use....................................................................... 2-26

2.11.3 Requirement to Obtain an LOA or IHA Prior to Receiving BOEM’s Approval........ 2-28

2.12 Mitigation Measures Considered but Not Carried Forward................................................. 2-29

2.12.1 Active Acoustic Monitoring ...................................................................................... 2-29

2.12.2 Aerial Surveys.......................................................................................................... 2-30

2.13 Comparison of Impacts by Alternative................................................................................. 2-31
Gulf of Mexico G&G Activities Programmatic EIS v 

2.14 Mitigation, Monitoring, and Effectiveness............................................................................ 2-38

2.14.1 Time and Area Restrictions and Closures............................................................... 2-39

2.14.2 Minimum Separation Distances............................................................................... 2-40

2.14.3 Non-Duplicative Surveys and Lowest Practicable Source...................................... 2-41

2.14.4 Exclusion Zone ........................................................................................................ 2-42

2.14.5 Exclusion Zone Monitoring ...................................................................................... 2-43

2.14.6 Ramp-Up ................................................................................................................. 2-48

2.14.7 Shutdowns of Sources for Protected Species......................................................... 2-48

2.14.8 Reduction in G&G Activity Levels............................................................................ 2-49

2.15 Adaptive Management......................................................................................................... 2-50

3 G&G ACTIVITIES AND PROPOSED ACTION SCENARIO.......................................................... 3-3

3.1 Introduction ............................................................................................................................ 3-3 

3.2 Proposed Action Scenario by Program Area......................................................................... 3-3

3.2.1 Oil and Gas Program G&G Surveys ......................................................................... 3-4

3.2.1.1 Proposed Action Scenario ......................................................................... 3-5 

3.2.1.2 Projected Activity Levels............................................................................ 3-5

3.2.2 Renewable Energy Program G&G Surveys.............................................................. 3-7

3.2.2.1 Proposed Action Scenario ......................................................................... 3-8 

3.2.2.2 Projected Activity Levels............................................................................ 3-9

3.2.3 Marine Minerals Program G&G Surveys................................................................. 3-10

3.2.3.1 Proposed Action Scenario ....................................................................... 3-11

3.2.3.2 Projected Activity Levels.......................................................................... 3-14

3.3 Impact-Producing Factors from the Proposed Action ......................................................... 3-16

3.3.1 Impact-Producing Factors for Routine Activities..................................................... 3-17

3.3.1.1 Active Acoustic Sound Sources............................................................... 3-17

3.3.1.1.1 Airguns.................................................................................. 3-17

3.3.1.1.2 Non-Airgun (Electromechanical) HRG Sources ................... 3-18

3.3.1.2 Vessel and Equipment Noise................................................................... 3-20

3.3.1.2.1 Vessel Noise......................................................................... 3-20

3.3.1.2.2 Equipment Noise Including Drilling Noise ............................ 3-21

3.3.1.3 Vessel Traffic ........................................................................................... 3-22

3.3.1.3.1 Surveys for Oil and Gas Exploration .................................... 3-22

3.3.1.3.2 Renewable Energy Surveys ................................................. 3-24

3.3.1.3.3 Marine Minerals Surveys ...................................................... 3-25

3.3.1.4 Aircraft Traffic and Noise ......................................................................... 3-25

3.3.1.5 Stand-Off Distance................................................................................... 3-27

3.3.1.6 Vessel Discharges ................................................................................... 3-27

3.3.1.7 Trash and Debris...................................................................................... 3-28

3.3.1.8 Seafloor Disturbance ............................................................................... 3-29

3.3.1.8.1 Seafloor or Bottom Sampling Activities ................................ 3-30

3.3.1.8.2 Placement of Anchors, Nodes, Cables, and Sensors .......... 3-31
vi Table of Contents

3.3.1.8.3 COST Wells and Shallow Test Drilling................................. 3-31

3.3.1.8.4 Bottom-Founded Monitoring Buoys...................................... 3-31

3.3.1.9 Drilling Discharges ................................................................................... 3-32

3.3.1.10 Entanglement........................................................................................... 3-33

3.3.2 Impact-Producing Factors for Accidental Fuel Spills .............................................. 3-34

3.4 Cumulative Activities Scenario ............................................................................................ 3-35

3.4.1 OCS Program .......................................................................................................... 3-37

3.4.1.1 OCS Oil and Gas Exploration and Development..................................... 3-37

3.4.1.2 Decommissioning..................................................................................... 3-38

3.4.1.3 Renewable Energy Development ............................................................ 3-39

3.4.1.4 Marine Minerals Use ................................................................................ 3-39

3.4.1.5 Geological and Geophysical Activity Related to the Oil and Gas 

Program.................................................................................................... 3-40

3.4.2 Oil and Gas Activities in State Waters .................................................................... 3-41

3.4.3 Other Major Factors Affecting Offshore Environments ........................................... 3-41

3.4.3.1 Deepwater Ports ...................................................................................... 3-41

3.4.3.2 Commercial and Recreational Fishing..................................................... 3-42

3.4.3.3 Shipping and Marine Transportation........................................................ 3-43

3.4.3.4 Dredged Material Disposal....................................................................... 3-44

3.4.3.5 Existing, Planned, and New Cable Infrastructure.................................... 3-45

3.4.3.6 Military Activities....................................................................................... 3-45

3.4.3.7 Scientific Research .................................................................................. 3-47

3.4.3.8 Maintenance Dredging of Federal Channels........................................... 3-47

3.4.3.9 Coastal Restoration Programs................................................................. 3-48

3.4.3.10 Mississippi River Hydromodification and Subsidence............................. 3-48

3.4.3.11 Natural Processes.................................................................................... 3-49

3.4.3.12 Recreational Activities.............................................................................. 3-50

4 DESCRIPTION OF THE AFFECTED RESOURCES AND IMPACT ANALYSIS .......................... 4-3

4.1 Introduction ............................................................................................................................ 4-3

4.1.1 Preliminary Screening of Activities and Affected Resources.................................... 4-4

4.1.1.1 Activity Screening....................................................................................... 4-5 

4.1.1.2 Resource Screening .................................................................................. 4-5

4.1.2 Impact-Level Definitions ............................................................................................ 4-7 

4.1.3 Impact-Producing Factors ......................................................................................... 4-9 

4.1.4 Other Considerations............................................................................................... 4-10

4.1.4.1 Analysis and Incomplete or Unavailable Information .............................. 4-10

4.1.4.2 Cumulative Scenario Summary ............................................................... 4-11

4.1.4.3 NMFS’ Technical Guidance ..................................................................... 4-12

4.1.4.4 Risk Assessment Framework .................................................................. 4-14

4.1.4.5 Space-Use Conflicts ................................................................................ 4-14

4.1.5 Effects of the Deepwater Horizon Oil Spill .............................................................. 4-15
Gulf of Mexico G&G Activities Programmatic EIS vii

4.2 Marine Mammals ................................................................................................................. 4-18

4.2.1 Description of the Affected Environment................................................................. 4-18

4.2.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) ......................... 4-24

4.2.2.1 Impacts of Routine Activities.................................................................... 4-25

4.2.2.1.1 Characteristics of Active Acoustic Sound Sources .............. 4-25

4.2.2.1.2 Analysis of Active Acoustic Sound Sources......................... 4-45

4.2.2.1.3 HRG Survey Activities .......................................................... 4-58

4.2.2.1.4 Vessel and Equipment Noise ............................................... 4-64

4.2.2.1.5 Drilling-Related Noise........................................................... 4-66

4.2.2.1.6 Vessel Traffic ........................................................................ 4-67

4.2.2.1.7 Aircraft Traffic and Noise ...................................................... 4-69

4.2.2.1.8 Trash and Debris .................................................................. 4-70

4.2.2.1.9 Entanglement........................................................................ 4-71

4.2.2.1.10 Routine Activities Impact Conclusions ................................. 4-72

4.2.2.2 Impacts of an Accidental Fuel Spill.......................................................... 4-73

4.2.2.3 Cumulative Impacts.................................................................................. 4-75

4.2.2.3.1 OCS Program G&G Survey Activities................................... 4-75

4.2.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities................................................................................ 4-75

4.2.2.3.3 Cumulative Impact Conclusions ........................................... 4-85

4.2.3 Impacts – Alternative B (Settlement Agreement Alternative).................................. 4-88

4.2.3.1 Impacts of Routine Activities.................................................................... 4-88

4.2.3.1.1 Coastal Waters Seasonal Restrictions ................................. 4-88

4.2.3.1.2 Expanded PSO Program ...................................................... 4-90

4.2.3.1.3 Minimum Separation Distances............................................ 4-92

4.2.3.1.4 Seismic Restrictions in the Areas of Concern within 

the EPA................................................................................. 4-93

4.2.3.1.5 Use of PAM Required........................................................... 4-95

4.2.3.1.6 Routine Activities Impact Conclusions ................................. 4-96

4.2.3.2 Impacts of an Accidental Fuel Spill.......................................................... 4-97

4.2.3.3 Cumulative Impacts.................................................................................. 4-98

4.2.3.3.1 OCS Program G&G Survey Activities................................... 4-98

4.2.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities................................................................................ 4-99

4.2.3.3.3 Cumulative Impact Conclusions ........................................... 4-99

4.2.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures)............................................................................................... 4-99

4.2.4.1 Impacts of Routine Activities..................................................................4-100

4.2.4.1.1 Coastal Waters Seasonal Restrictions (February 1 to 

May 31)...............................................................................4-100

4.2.4.1.2 Expanded PSO Program ....................................................4-100

4.2.4.1.3 Use of PAM Required.........................................................4-101
viii Table of Contents

4.2.4.1.4 Non-Airgun HRG Survey Protocol......................................4-102

4.2.4.1.5 Routine Activities Impact Conclusions ...............................4-103

4.2.4.2 Impacts of an Accidental Fuel Spill........................................................4-104

4.2.4.3 Cumulative Impacts................................................................................4-105

4.2.4.3.1 OCS Program G&G Survey Activities.................................4-105

4.2.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-105

4.2.4.3.3 Cumulative Impact Conclusions .........................................4-105

4.2.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns) ...........4-106

4.2.5.1 Impacts of Routine Activities..................................................................4-106

4.2.5.1.1 Expanded PSO Program with Additional Shutdowns.........4-106

4.2.5.1.2 Routine Activities Impact Conclusions ...............................4-107

4.2.5.2 Impacts of an Accidental Fuel Spill........................................................4-108

4.2.5.3 Cumulative Impacts................................................................................4-108

4.2.5.3.1 OCS Program G&G Survey Activities.................................4-108

4.2.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-109

4.2.5.3.3 Cumulative Impact Conclusions .........................................4-109

4.2.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-109

4.2.6.1 Impacts of Routine Activities..................................................................4-109

4.2.6.1.1 Reduced Level of Activity ...................................................4-109

4.2.6.1.2 Routine Activities Impact Conclusions ...............................4-110

4.2.6.2 Impacts of an Accidental Fuel Spill........................................................4-112

4.2.6.3 Cumulative Impacts................................................................................4-112

4.2.6.3.1 OCS Program G&G Survey Activities.................................4-112

4.2.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-113

4.2.6.3.3 Cumulative Impact Conclusions .........................................4-113

4.2.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-113

4.2.7.1 Impacts of Routine Activities..................................................................4-113

4.2.7.1.1 Closure Areas .....................................................................4-113

4.2.7.1.2 Routine Activities Impact Conclusions ...............................4-118

4.2.7.2 Impacts of an Accidental Fuel Spill........................................................4-120

4.2.7.3 Cumulative Impacts................................................................................4-120

4.2.7.3.1 OCS Program G&G Survey Activities.................................4-120

4.2.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-121

4.2.7.3.3 Cumulative Impact Conclusions .........................................4-121

4.2.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-121

4.2.8.1 OCS Program G&G Survey Activities....................................................4-121

4.2.8.2 Impacts of an Accidental Fuel Spill........................................................4-124
Gulf of Mexico G&G Activities Programmatic EIS ix

4.2.8.3 Activities Other Than OCS Program G&G Survey Activities.................4-124

4.2.8.4 Cumulative Impact Conclusions ............................................................4-124

4.2.9 Summary Conclusion ............................................................................................4-125

4.3 Sea Turtles.........................................................................................................................4-126

4.3.1 Description of the Affected Environment...............................................................4-126

4.3.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative)........................4-129

4.3.2.1 Impacts of Routine Activities..................................................................4-130

4.3.2.1.1 Characteristics of Active Acoustic Sound Sources ............4-130

4.3.2.1.2 Analysis of Active Acoustic Sound Sources.......................4-138

4.3.2.1.3 Vessel and Equipment Noise .............................................4-142

4.3.2.1.4 Vessel Traffic ......................................................................4-144

4.3.2.1.5 Aircraft Traffic and Noise ....................................................4-145

4.3.2.1.6 Trash and Debris ................................................................4-146

4.3.2.1.7 Entanglement and Entrapment...........................................4-147

4.3.2.1.8 Routine Activities Impact Conclusions ...............................4-148

4.3.2.2 Impacts of an Accidental Fuel Spill........................................................4-149

4.3.2.3 Cumulative Impacts................................................................................4-151

4.3.2.3.1 OCS Program G&G Survey Activities.................................4-151

4.3.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-151

4.3.2.3.3 Cumulative Impact Conclusions .........................................4-159

4.3.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-160

4.3.3.1 Impacts of Routine Activities..................................................................4-161

4.3.3.1.1 Coastal Waters Seasonal Restrictions ...............................4-161

4.3.3.1.2 Expanded PSO Program ....................................................4-162

4.3.3.1.3 Minimum Separation Distances..........................................4-163

4.3.3.1.4 Seismic Restrictions in the Areas of Concern within 

the EPA...............................................................................4-164

4.3.3.1.5 Routine Activities Impact Conclusions ...............................4-165

4.3.3.2 Impacts of an Accidental Fuel Spill........................................................4-166

4.3.3.3 Cumulative Impacts................................................................................4-166

4.3.3.3.1 OCS Program G&G Survey Activities.................................4-166

4.3.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-167

4.3.3.3.3 Cumulative Impact Conclusions .........................................4-167

4.3.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures) ..............................................................................................4-168

4.3.4.1 Impacts of Routine Activities..................................................................4-168

4.3.4.1.1 Coastal Waters Seasonal Restrictions (February 1 to 

May 31)...............................................................................4-168

4.3.4.1.2 Expanded PSO Program ....................................................4-168

4.3.4.1.3 Non-Airgun HRG Survey Protocol......................................4-169

4.3.4.1.4 Routine Activities Impact Conclusions ...............................4-170
x Table of Contents

4.3.4.2 Impacts of Accidental Fuel Spills ...........................................................4-171

4.3.4.3 Cumulative Impacts................................................................................4-171

4.3.4.3.1 OCS Program G&G Survey Activities.................................4-171

4.3.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-171

4.3.4.3.3 Cumulative Impact Conclusions .........................................4-172

4.3.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-172

4.3.5.1 Impacts of Routine Activities..................................................................4-172

4.3.5.2 Impacts of an Accidental Fuel Spill........................................................4-172

4.3.5.3 Cumulative Impacts................................................................................4-173

4.3.5.3.1 OCS Program G&G Survey Activities.................................4-173

4.3.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-173

4.3.5.3.3 Cumulative Impact Conclusions .........................................4-173

4.3.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-173

4.3.6.1 Impacts of Routine Activities..................................................................4-174

4.3.6.1.1 Reduced Level of Activity ...................................................4-174

4.3.6.2 Impacts of an Accidental Fuel Spill........................................................4-174

4.3.6.3 Cumulative Impacts................................................................................4-174

4.3.6.3.1 OCS Program G&G Survey Activities.................................4-174

4.3.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-175

4.3.6.3.3 Cumulative Impact Conclusions .........................................4-175

4.3.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-175

4.3.7.1 Impacts of Routine Activities..................................................................4-175

4.3.7.1.1 Closure Areas .....................................................................4-175

4.3.7.2 Impacts of an Accidental Fuel Spill........................................................4-176

4.3.7.3 Cumulative Impacts................................................................................4-176

4.3.7.3.1 OCS Program G&G Survey Activities.................................4-176

4.3.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-177

4.3.7.3.3 Cumulative Impact Conclusions .........................................4-177

4.3.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-177

4.3.9 Summary Conclusion ............................................................................................4-179

4.4 Fish Resources and Essential Fish Habitat.......................................................................4-179

4.4.1 Description of the Affected Environment...............................................................4-179

4.4.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) .......................4-182

4.4.2.1 Impacts of Routine Activities..................................................................4-183

4.4.2.1.1 Background: Potential Effects of Noise on Fishes ............4-183

4.4.2.1.2 Analysis of Active Acoustic Sound Sources.......................4-189

4.4.2.1.3 Vessel and Equipment Noise .............................................4-192

4.4.2.1.4 Trash and Debris ................................................................4-193

4.4.2.1.5 Seafloor Disturbance ..........................................................4-194
Gulf of Mexico G&G Activities Programmatic EIS xi

4.4.2.1.6 Drilling Discharges..............................................................4-195

4.4.2.1.7 Entanglement......................................................................4-195

4.4.2.1.8 Routine Activities Impact Conclusions ...............................4-196

4.4.2.2 Impacts of an Accidental Fuel Spill........................................................4-196

4.4.2.3 Cumulative Impacts................................................................................4-197

4.4.2.3.1 OCS Program G&G Survey Activities.................................4-197

4.4.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-197

4.4.2.3.3 Cumulative Impact Conclusions .........................................4-203

4.4.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-204

4.4.3.1 Impacts of Routine Activities..................................................................4-204

4.4.3.1.1 Coastal Waters Seasonal Restrictions ...............................4-204

4.4.3.1.2 Minimum Separation Distances..........................................4-205

4.4.3.1.3 Seismic Restrictions in the Areas of Concern within 

the EPA...............................................................................4-205

4.4.3.1.4 Routine Activities Impact Conclusions ...............................4-206

4.4.3.2 Impacts of an Accidental Fuel Spill........................................................4-206

4.4.3.3 Cumulative Impacts................................................................................4-207

4.4.3.3.1 OCS Program G&G Survey Activities.................................4-207

4.4.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-207

4.4.3.3.3 Cumulative Impact Conclusions .........................................4-207

4.4.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures).............................................................................................4-208

4.4.4.1 Impacts of Routine Activities..................................................................4-208

4.4.4.1.1 Coastal Waters Seasonal Restrictions (February 1 to 

May 31)...............................................................................4-208

4.4.4.1.2 Routine Activities Impact Conclusions ...............................4-208

4.4.4.2 Impacts of an Accidental Fuel Spill........................................................4-209

4.4.4.3 Cumulative Impacts................................................................................4-209

4.4.4.3.1 OCS Program G&G Survey Activities.................................4-209

4.4.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-209

4.4.4.3.3 Cumulative Impact Conclusions .........................................4-210

4.4.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-210

4.4.5.1 Impacts of Routine Activities..................................................................4-210

4.4.5.2 Impacts of an Accidental Fuel Spill........................................................4-210

4.4.5.3 Cumulative Impacts................................................................................4-211

4.4.5.3.1 OCS Program G&G Survey Activities.................................4-211

4.4.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-211

4.4.5.3.3 Cumulative Impact Conclusions .........................................4-211
xii Table of Contents

4.4.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-211

4.4.6.1 Impacts of Routine Activities..................................................................4-212

4.4.6.1.1 Reduced Level of Activity ...................................................4-212

4.4.6.2 Impacts of an Accidental Fuel Spill........................................................4-212

4.4.6.3 Cumulative Impacts................................................................................4-213

4.4.6.3.1 OCS Program G&G Survey Activities.................................4-213

4.4.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-213

4.4.6.3.3 Cumulative Impact Conclusions .........................................4-213

4.4.7 Impacts – Alternative F (Alternative C Plus Area Closures) .................................4-214

4.4.7.1 Impacts of Routine Activities..................................................................4-214

4.4.7.1.1 Closure Areas .....................................................................4-214

4.4.7.2 Impacts of an Accidental Fuel Spill........................................................4-215

4.4.7.3 Cumulative Impacts................................................................................4-215

4.4.7.3.1 OCS Program G&G Survey Activities.................................4-215

4.4.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-215

4.4.7.3.3 Cumulative Impact Conclusions .........................................4-216

4.4.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-216

4.4.9 Summary Conclusion ............................................................................................4-217

4.5 Benthic Communities.........................................................................................................4-217

4.5.1 Description of the Affected Environment...............................................................4-217

4.5.1.1 Soft Bottom Communities ......................................................................4-219

4.5.1.2 Hard Bottom Communities.....................................................................4-219

4.5.1.2.1 Deepwater Coral Communities...........................................4-219

4.5.1.2.2 Live Bottoms (Pinnacle Trend) ...........................................4-220

4.5.1.2.3 Live Bottoms (Low Relief)...................................................4-220

4.5.1.2.4 Topographic Features.........................................................4-220

4.5.1.2.5 Artificial Reefs.....................................................................4-221

4.5.1.3 Chemosynthetic Communities ...............................................................4-221

4.5.1.4 Listed, Candidate, and Species of Concern ..........................................4-222

4.5.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) .......................4-222

4.5.2.1 Impacts of Routine Activities..................................................................4-224

4.5.2.1.1 Active Acoustic Sound Sources..........................................4-224

4.5.2.1.2 Trash and Debris ................................................................4-225

4.5.2.1.3 Seafloor Disturbance ..........................................................4-226

4.5.2.1.4 Drilling Discharges..............................................................4-228

4.5.2.1.5 Routine Activities Impact Conclusions ...............................4-229

4.5.2.2 Impacts of an Accidental Fuel Spill........................................................4-230
Gulf of Mexico G&G Activities Programmatic EIS xiii

4.5.2.3 Cumulative Impacts................................................................................4-230

4.5.2.3.1 OCS Program G&G Survey Activities.................................4-230

4.5.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-230

4.5.2.3.3 Cumulative Impact Conclusions .........................................4-235

4.5.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-235

4.5.3.1 Impacts of Routine Activities..................................................................4-236

4.5.3.1.1 Coastal Waters Seasonal Restrictions (January 1 to 

April 30)...............................................................................4-236

4.5.3.1.2 Seismic Restrictions in the Areas of Concern within 

the EPA...............................................................................4-236

4.5.3.1.3 Routine Activities Impact Conclusions ...............................4-236

4.5.3.2 Impacts of an Accidental Fuel Spill........................................................4-236

4.5.3.3 Cumulative Impacts................................................................................4-236

4.5.3.3.1 OCS Program G&G Survey Activities.................................4-236

4.5.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-237

4.5.3.3.3 Cumulative Impact Conclusions .........................................4-237

4.5.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures).............................................................................................4-237

4.5.4.1 Impacts of Routine Activities..................................................................4-238

4.5.4.1.1 Coastal Waters Seasonal Restrictions (February 1 to 

May 31) ...............................................................................4-238

4.5.4.1.2 Routine Activities Impact Conclusions ...............................4-238

4.5.4.2 Impacts of an Accidental Fuel Spill........................................................4-238

4.5.4.3 Cumulative Impacts................................................................................4-238

4.5.4.3.1 OCS Program G&G survey activities .................................4-238

4.5.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-238

4.5.4.3.3 Cumulative Impact Conclusions .........................................4-239

4.5.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-239

4.5.5.1 Impacts of Routine Activities..................................................................4-239

4.5.5.2 Impacts of an Accidental Fuel Spill........................................................4-239

4.5.5.3 Cumulative Impacts................................................................................4-240

4.5.5.3.1 OCS Program G&G Survey Activities.................................4-240

4.5.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-240

4.5.5.3.3 Cumulative Impact Conclusions .........................................4-240

4.5.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-240

4.5.6.1 Impacts of Routine Activities..................................................................4-241

4.5.6.1.1 Reduced Level of Activity ...................................................4-241

4.5.6.1.2 Routine Activities Impact Conclusions ...............................4-241

4.5.6.2 Impacts of an Accidental Fuel Spill........................................................4-241
xiv Table of Contents

4.5.6.3 Cumulative Impacts................................................................................4-241

4.5.6.3.1 OCS Program G&G Survey Activities.................................4-241

4.5.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-242

4.5.6.3.3 Cumulative Impact Conclusions .........................................4-242

4.5.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-242

4.5.7.1 Impacts of Routine Activities..................................................................4-242

4.5.7.1.1 Closure Areas .....................................................................4-242

4.5.7.1.2 Routine Activities Impact Conclusions ...............................4-242

4.5.7.2 Impacts of an Accidental Fuel Spill........................................................4-243

4.5.7.2.1 Cumulative Impacts ............................................................4-243

4.5.7.2.2 OCS Program G&G survey activities .................................4-243

4.5.7.2.3 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-243

4.5.7.2.4 Cumulative Impact Conclusions .........................................4-244

4.5.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-244

4.5.9 Summary Conclusion ............................................................................................4-245

4.6 Marine and Coastal Birds ..................................................................................................4-245

4.6.1 Description of the Affected Environment...............................................................4-245

4.6.1.1 Unlisted Species ....................................................................................4-245

4.6.1.2 Listed Species........................................................................................4-247

4.6.1.3 Effects of the Deepwater Horizon Oil Spill on Marine and Coastal 

Birds .......................................................................................................4-247

4.6.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) .......................4-249

4.6.2.1 Impacts of Routine Activities..................................................................4-250

4.6.2.1.1 Active Acoustic Sound Sources..........................................4-250

4.6.2.1.2 Vessel and Equipment Noise and Vessel Traffic ...............4-253

4.6.2.1.3 Aircraft Traffic and Noise ....................................................4-258

4.6.2.1.4 Trash and Debris ................................................................4-259

4.6.2.1.5 Routine Activities Impact Conclusions ...............................4-260

4.6.2.2 Impacts of an Accidental Fuel Spill........................................................4-260

4.6.2.3 Cumulative Impacts................................................................................4-261

4.6.2.3.1 OCS Program G&G Survey Activities.................................4-261

4.6.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-261

4.6.2.3.3 Cumulative Impact Conclusions .........................................4-267

4.6.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-269

4.6.3.1 Impacts of Routine Activities..................................................................4-269

4.6.3.1.1 Coastal Waters Seasonal Restrictions ...............................4-269

4.6.3.1.2 Minimum Separation Distances..........................................4-270

4.6.3.1.3 Seismic Restrictions in the Areas of Concern within 

the EPA...............................................................................4-270
Gulf of Mexico G&G Activities Programmatic EIS xv

4.6.3.1.4 Routine Activities Impact Conclusions ...............................4-271

4.6.3.1.5 Impacts of an Accidental Fuel Spill.....................................4-272

4.6.3.2 Cumulative Impacts................................................................................4-272

4.6.3.2.1 OCS Program G&G Survey Activities.................................4-272

4.6.3.2.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-272

4.6.3.2.3 Cumulative Impact Conclusions .........................................4-273

4.6.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures).............................................................................................4-273

4.6.4.1 Impacts of Routine Activities..................................................................4-273

4.6.4.1.1 Coastal Waters Seasonal Restrictions (February 1 to 

May 31)...............................................................................4-273

4.6.4.1.2 Routine Activities Impact Conclusions ...............................4-274

4.6.4.2 Impacts of an Accidental Fuel Spill........................................................4-274

4.6.4.3 Cumulative Impacts................................................................................4-275

4.6.4.3.1 OCS Program G&G Survey Activities.................................4-275

4.6.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-275

4.6.4.3.3 Cumulative Impact Conclusions .........................................4-275

4.6.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-275

4.6.5.1 Impacts of Routine Activities..................................................................4-276

4.6.5.2 Impacts of an Accidental Fuel Spill........................................................4-276

4.6.5.3 Cumulative Impacts................................................................................4-277

4.6.5.3.1 OCS Program G&G Survey Activities.................................4-277

4.6.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-277

4.6.5.3.3 Cumulative Impact Conclusions .........................................4-277

4.6.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-277

4.6.6.1 Impacts of Routine Activities..................................................................4-278

4.6.6.1.1 Reduced Level of Activity ...................................................4-278

4.6.6.1.2 Routine Activities Impact Conclusions ...............................4-279

4.6.6.2 Impacts of an Accidental Fuel Spill........................................................4-279

4.6.6.3 Cumulative Impacts................................................................................4-279

4.6.6.3.1 OCS Program G&G Survey Activities.................................4-279

4.6.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-280

4.6.6.3.3 Cumulative Impact Conclusions .........................................4-280

4.6.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-280

4.6.7.1 Impacts of Routine Activities..................................................................4-280

4.6.7.2 Impacts of an Accidental Fuel Spill........................................................4-281
xvi Table of Contents

4.6.7.3 Cumulative Impacts................................................................................4-281

4.6.7.3.1 OCS Program G&G Survey Activities.................................4-281

4.6.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-281

4.6.7.3.3 Cumulative Impact Conclusions .........................................4-282

4.6.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-282

4.6.9 Summary Conclusion ............................................................................................4-283

4.7 Marine Protected Areas......................................................................................................4-283

4.7.1 Description of the Affected Environment...............................................................4-283

4.7.1.1 Offshore Marine Protected Areas ..........................................................4-284

4.7.1.2 Coastal Marine Protected Areas............................................................4-287

4.7.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) .......................4-289

4.7.2.1 Impacts of Routine Activities..................................................................4-291

4.7.2.1.1 Active Acoustic Sound Sources..........................................4-291

4.7.2.1.2 Trash and Debris ................................................................4-295

4.7.2.1.3 Seafloor Disturbance ..........................................................4-296

4.7.2.1.4 Drilling Discharges..............................................................4-296

4.7.2.1.5 Routine Activities Impact Conclusions ...............................4-298

4.7.2.2 Impacts of an Accidental Fuel Spill........................................................4-298

4.7.2.3 Cumulative Impacts................................................................................4-299

4.7.2.3.1 OCS Program G&G Survey Activities.................................4-299

4.7.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-299

4.7.2.3.3 Cumulative Impact Conclusions .........................................4-302

4.7.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-302

4.7.3.1 Impacts of Routine Activities..................................................................4-302

4.7.3.1.1 Coastal Waters Seasonal Restrictions ...............................4-302

4.7.3.1.2 Expanded PSO Program ....................................................4-303

4.7.3.1.3 Minimum Separation Distances..........................................4-303

4.7.3.1.4 Seismic Restrictions in the Areas of Concern within 

the EPA...............................................................................4-303

4.7.3.1.5 Use of PAM Required.........................................................4-303

4.7.3.1.6 Routine Activities Impact Conclusions ...............................4-303

4.7.3.2 Impacts of an Accidental Fuel Spill........................................................4-304

4.7.3.3 Cumulative Impacts................................................................................4-304

4.7.3.3.1 OCS Program G&G Survey Activities.................................4-304

4.7.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-304

4.7.3.3.3 Cumulative Impact Conclusions .........................................4-305
Gulf of Mexico G&G Activities Programmatic EIS xvii

4.7.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures).............................................................................................4-305

4.7.4.1 Impacts of Routine Activities..................................................................4-305

4.7.4.1.1 Coastal Waters Seasonal Restrictions (February 1 to 

May 31)...............................................................................4-305

4.7.4.1.2 Expanded PSO Program ....................................................4-306

4.7.4.1.3 Use of PAM Required.........................................................4-306

4.7.4.1.4 Non-Airgun HRG Survey Protocol......................................4-306

4.7.4.1.5 Routine Activities Impact Conclusions ...............................4-306

4.7.4.2 Impacts of an Accidental Fuel Spill........................................................4-306

4.7.4.3 Cumulative Impacts................................................................................4-307

4.7.4.3.1 OCS Program G&G Survey Activities.................................4-307

4.7.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-307

4.7.4.3.3 Cumulative Impact Conclusions .........................................4-307

4.7.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-307

4.7.5.1 Impacts of Routine Activities..................................................................4-308

4.7.5.2 Impacts of an Accidental Fuel Spill........................................................4-308

4.7.5.3 Cumulative Impacts................................................................................4-309

4.7.5.3.1 OCS Program G&G Survey Activities.................................4-309

4.7.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-309

4.7.5.3.3 Cumulative Impact Conclusions .........................................4-309

4.7.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-309

4.7.6.1 Impacts of Routine Activities..................................................................4-309

4.7.6.2 Impacts of an Accidental Fuel Spill........................................................4-310

4.7.6.3 Cumulative Impacts................................................................................4-310

4.7.6.3.1 OCS Program G&G Survey Activities.................................4-310

4.7.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-311

4.7.6.3.3 Cumulative Impact Conclusions .........................................4-311

4.7.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-311

4.7.7.1 Impacts of Routine Activities..................................................................4-311

4.7.7.2 Impacts of an Accidental Fuel Spill........................................................4-312

4.7.7.3 Cumulative Impacts................................................................................4-312

4.7.7.3.1 OCS Program G&G Survey Activities.................................4-312

4.7.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-313

4.7.7.3.3 Cumulative Impact Conclusions .........................................4-313

4.7.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-313

4.7.9 Summary Conclusion ............................................................................................4-314
xviii Table of Contents

4.8 Sargassum and Associated Communities .........................................................................4-315

4.8.1 Description of the Affected Environment...............................................................4-315

4.8.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) .......................4-316

4.8.2.1 Impacts of Routine Activities..................................................................4-318

4.8.2.1.1 Vessel Traffic ......................................................................4-318

4.8.2.1.2 Vessel Discharges ..............................................................4-318

4.8.2.1.3 Trash and Debris ................................................................4-319

4.8.2.1.4 Routine Activities Impact Conclusions ...............................4-320

4.8.2.2 Impacts of an Accidental Fuel Spill........................................................4-320

4.8.2.3 Cumulative Impacts................................................................................4-321

4.8.2.3.1 OCS Program G&G Survey Activities.................................4-321

4.8.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-322

4.8.2.3.3 Cumulative Impact Conclusions .........................................4-325

4.8.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-325

4.8.3.1 Impacts of Routine Activities..................................................................4-325

4.8.3.1.1 Coastal Waters Seasonal Restrictions ...............................4-325

4.8.3.1.2 Seismic Restrictions in the Areas of Concern within 

the EPA...............................................................................4-326

4.8.3.1.3 Routine Activities Impact Conclusions ...............................4-326

4.8.3.2 Impacts of an Accidental Fuel Spill........................................................4-326

4.8.3.3 Cumulative Impacts................................................................................4-327

4.8.3.3.1 OCS Program G&G Survey Activities.................................4-327

4.8.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-327

4.8.3.3.3 Cumulative Impact Conclusions .........................................4-327

4.8.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures).............................................................................................4-327

4.8.4.1 Impacts of Routine Activities..................................................................4-328

4.8.4.1.1 Coastal Waters Seasonal Restrictions (February 1 to 

May 31)...............................................................................4-328

4.8.4.1.2 Routine Activities Impact Conclusions ...............................4-328

4.8.4.2 Impacts of an Accidental Fuel Spill........................................................4-328

4.8.4.3 Cumulative Impacts................................................................................4-329

4.8.4.3.1 OCS Program G&G Survey Activities.................................4-329

4.8.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-329

4.8.4.3.3 Cumulative Impact Conclusions .........................................4-329

4.8.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-329

4.8.5.1 Impacts of Routine Activities..................................................................4-330

4.8.5.2 Impacts of an Accidental Fuel Spill........................................................4-330
Gulf of Mexico G&G Activities Programmatic EIS xix

4.8.5.3 Cumulative Impacts................................................................................4-330

4.8.5.3.1 OCS Program G&G Survey Activities.................................4-330

4.8.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-331

4.8.5.3.3 Cumulative Impact Conclusions .........................................4-331

4.8.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-331

4.8.6.1 Impacts of Routine Activities..................................................................4-331

4.8.6.2 Impacts of an Accidental Fuel Spill........................................................4-331

4.8.6.3 Cumulative Impacts................................................................................4-332

4.8.6.3.1 OCS Program G&G Survey Activities.................................4-332

4.8.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-332

4.8.6.3.3 Cumulative Impact Conclusions .........................................4-332

4.8.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-332

4.8.7.1 Impacts of Routine Activities..................................................................4-332

4.8.7.2 Impacts of an Accidental Fuel Spill........................................................4-333

4.8.7.3 Cumulative Impacts................................................................................4-333

4.8.7.3.1 OCS Program G&G Survey Activities.................................4-333

4.8.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-333

4.8.7.3.3 Cumulative Impact Conclusions .........................................4-333

4.8.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-334

4.8.9 Summary Conclusion ............................................................................................4-334

4.9 Commercial Fisheries.........................................................................................................4-335

4.9.1 Description of the Affected Environment...............................................................4-335

4.9.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) .......................4-336

4.9.2.1 Impacts of Routine Activities..................................................................4-337

4.9.2.1.1 Active Acoustic Sound Sources..........................................4-337

4.9.2.1.2 Vessel Traffic ......................................................................4-340

4.9.2.1.3 Stand-Off Distance .............................................................4-340

4.9.2.1.4 Seafloor Disturbance ..........................................................4-341

4.9.2.1.5 Entanglement......................................................................4-342

4.9.2.1.6 Routine Activities Impact Conclusions ...............................4-343

4.9.2.2 Impacts of an Accidental Fuel Spill........................................................4-343

4.9.2.3 Cumulative Impacts................................................................................4-343

4.9.2.3.1 OCS Program G&G Survey Activities.................................4-343

4.9.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-344

4.9.2.3.3 Cumulative Impact Conclusions .........................................4-348

4.9.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-348

4.9.3.1 Impacts of Routine Activities..................................................................4-348

4.9.3.1.1 Coastal Waters Seasonal Restrictions ...............................4-348

4.9.3.1.2 Minimum Separation Distances..........................................4-349
xx Table of Contents

4.9.3.1.3 Seismic Restrictions in the Areas of Concern within 

the EPA...............................................................................4-349

4.9.3.1.4 Routine Activities Impact Conclusions ...............................4-350

4.9.3.2 Impacts of an Accidental Fuel Spill........................................................4-350

4.9.3.3 Cumulative Impacts................................................................................4-351

4.9.3.3.1 OCS Program G&G Survey Activities.................................4-351

4.9.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-351

4.9.3.3.3 Cumulative Impact Conclusions .........................................4-351

4.9.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures).............................................................................................4-351

4.9.4.1 Impacts of Routine Activities..................................................................4-351

4.9.4.1.1 Coastal Waters Seasonal Restrictions (February 1 to 

May 31)...............................................................................4-352

4.9.4.1.2 Routine Activities Impact Conclusions ...............................4-352

4.9.4.2 Impacts of an Accidental Fuel Spill........................................................4-352

4.9.4.3 Cumulative Impacts................................................................................4-353

4.9.4.3.1 OCS Program G&G Survey Activities.................................4-353

4.9.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-353

4.9.4.3.3 Cumulative Impact Conclusions .........................................4-353

4.9.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-353

4.9.5.1 Impacts of Routine Activities..................................................................4-354

4.9.5.2 Impacts of an Accidental Fuel Spill........................................................4-354

4.9.5.3 Cumulative Impacts................................................................................4-354

4.9.5.3.1 OCS Program G&G Survey Activities.................................4-354

4.9.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-354

4.9.5.3.3 Cumulative Impact Conclusions .........................................4-355

4.9.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-355

4.9.6.1 Impacts of Routine Activities..................................................................4-355

4.9.6.2 Impacts of an Accidental Fuel Spill........................................................4-356

4.9.6.3 Cumulative Impacts................................................................................4-357

4.9.6.3.1 OCS Program G&G Survey Activities.................................4-357

4.9.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-357

4.9.6.3.3 Cumulative Impact Conclusions .........................................4-357

4.9.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-357

4.9.7.1 Impacts of Routine Activities..................................................................4-358

4.9.7.1.1 Closure Areas .....................................................................4-358

4.9.7.1.2 Routine Activities Impact Conclusions ...............................4-358

4.9.7.2 Impacts of an Accidental Fuel Spill........................................................4-358
Gulf of Mexico G&G Activities Programmatic EIS xxi

4.9.7.3 Cumulative Impacts................................................................................4-359

4.9.7.3.1 OCS Program G&G Survey Activities.................................4-359

4.9.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-359

4.9.7.3.3 Cumulative Impact Conclusions .........................................4-359

4.9.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-359

4.9.9 Summary Conclusion ............................................................................................4-360

4.10 Recreational Fisheries.......................................................................................................4-361

4.10.1 Description of the Affected Environment...............................................................4-361

4.10.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) .......................4-363

4.10.2.1 Impacts of Routine Activities..................................................................4-364

4.10.2.1.1 Routine Activities Impact Conclusions ...............................4-367

4.10.2.2 Impacts of an Accidental Fuel Spill........................................................4-367

4.10.2.3 Cumulative Impacts................................................................................4-367

4.10.2.3.1 OCS Program G&G Survey Activities.................................4-368

4.10.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-368

4.10.2.3.3 Cumulative Impact Conclusions ........................................4-371

4.10.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-371

4.10.3.1 Impacts of Routine Activities..................................................................4-371

4.10.3.1.1 Seasonal Restriction for Federal Coastal Waters ..............4-371

4.10.3.1.2 Minimum Separation Distances..........................................4-372

4.10.3.1.3 Seismic Restrictions in the EPA .........................................4-372

4.10.3.1.4 Routine Activities Impact Conclusions ...............................4-373

4.10.3.2 Impacts of an Accidental Fuel Spill........................................................4-373

4.10.3.3 Cumulative Impacts................................................................................4-373

4.10.3.3.1 OCS Program G&G Survey Activities.................................4-373

4.10.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-374

4.10.3.3.3 Cumulative Impact Conclusions .........................................4-374

4.10.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures).............................................................................................4-374

4.10.4.1 Impacts of Routine Activities..................................................................4-375

4.10.4.1.1 Seasonal Restriction for all Coastal Waters (February 1 

to May 31)...........................................................................4-375

4.10.4.1.2 Routine Activities Impact Conclusions ...............................4-375

4.10.4.2 Impacts of an Accidental Fuel Spill........................................................4-376

4.10.4.3 Cumulative Impacts................................................................................4-376

4.10.4.3.1 OCS Program G&G Survey Activities.................................4-376

4.10.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-376

4.10.4.3.3 Cumulative Impact Conclusions .........................................4-376
xxii Table of Contents

4.10.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-377

4.10.5.1 Impacts of Routine Activities..................................................................4-377

4.10.5.2 Impacts of an Accidental Fuel Spill........................................................4-377

4.10.5.3 Cumulative Impacts................................................................................4-377

4.10.5.3.1 OCS Program G&G Survey Activities.................................4-377

4.10.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-377

4.10.5.3.3 Cumulative Impact Conclusions .........................................4-377

4.10.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-378

4.10.6.1 Impacts of Routine Activities..................................................................4-378

4.10.6.1.1 Reduction of G&G Activity Levels.......................................4-378

4.10.6.2 Impacts of an Accidental Fuel Spill........................................................4-379

4.10.6.3 Cumulative Impacts................................................................................4-379

4.10.6.3.1 OCS Program G&G Survey Activities.................................4-379

4.10.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-379

4.10.6.3.3 Cumulative Impact Conclusions .........................................4-379

4.10.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-380

4.10.7.1 Impacts of Routine Activities..................................................................4-380

4.10.7.1.1 Area Closures .....................................................................4-380 

4.10.7.1.2 Routine Activities Impact Conclusions ...............................4-380

4.10.7.2 Impacts of an Accidental Fuel Spill........................................................4-380

4.10.7.3 Cumulative Impacts................................................................................4-380

4.10.7.3.1 OCS Program G&G Survey Activities.................................4-380

4.10.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-381

4.10.7.3.3 Cumulative Impact Conclusions .........................................4-381

4.10.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-381

4.10.9 Summary Conclusion ............................................................................................4-382

4.11 Archaeological Resources.................................................................................................4-382

4.11.1 Description of the Affected Environment...............................................................4-382

4.11.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) .......................4-383

4.11.2.1 Impacts of Routine Activities..................................................................4-385

4.11.2.1.1 Seafloor Disturbance and Entanglement............................4-385

4.11.2.1.2 Drilling Discharges..............................................................4-387

4.11.2.1.3 Routine Activities Impact Conclusions ...............................4-387

4.11.2.2 Impacts of an Accidental Fuel Spill........................................................4-388

4.11.2.3 Cumulative Impacts................................................................................4-388

4.11.2.3.1 OCS Program G&G Survey Activities.................................4-388

4.11.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-388

4.11.2.3.3 Cumulative Impact Conclusions .........................................4-393
Gulf of Mexico G&G Activities Programmatic EIS xxiii

4.11.3 Impacts – Alternatives B through F.......................................................................4-393

4.11.3.1 Impacts of Routine Activities..................................................................4-393

4.11.3.2 Impacts of an Accidental Fuel Spill........................................................4-394

4.11.3.3 Cumulative Impacts................................................................................4-394

4.11.3.3.1 OCS Program G&G Survey Activities.................................4-394

4.11.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-394

4.11.3.3.3 Cumulative Impact Conclusions .........................................4-394

4.11.4 Impacts – Alternative G (No New Activity Alternative)..........................................4-395

4.11.5 Summary Conclusion ............................................................................................4-396

4.12 Multiple-Use Areas ............................................................................................................4-396

4.12.1 Description of the Affected Environment...............................................................4-396

4.12.1.1 Shipping and Marine Transportation......................................................4-397

4.12.1.2 Military Warning Areas and Other Military Uses....................................4-398

4.12.1.3 Sand and Gravel Mining ........................................................................4-398

4.12.1.4 Renewable Energy Development – Wind Energy .................................4-399

4.12.1.5 Ocean Dredged Material Disposal Sites................................................4-399

4.12.1.6 Oil and Gas Exploration, Development, and Production.......................4-400

4.12.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative) .......................4-401

4.12.2.1 Impacts of Routine Activities..................................................................4-402

4.12.2.1.1 Vessel Traffic and Stand-Off Distance ...............................4-402

4.12.2.1.2 Aircraft Traffic......................................................................4-405

4.12.2.1.3 Seafloor Disturbance ..........................................................4-405

4.12.2.1.4 Routine Activities Impact Conclusions ...............................4-407

4.12.2.2 Impacts of an Accidental Fuel Spill........................................................4-407

4.12.2.3 Cumulative Impacts................................................................................4-408

4.12.2.3.1 OCS Program G&G Survey Activities.................................4-408

4.12.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-408

4.12.2.3.3 Cumulative Impact Conclusions .........................................4-410

4.12.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-411

4.12.3.1 Impacts of Routine Activities..................................................................4-411

4.12.3.1.1 Coastal Waters Seasonal Restrictions (January 1 to 

April 30)...............................................................................4-411

4.12.3.1.2 Minimum Separation Distances..........................................4-411

4.12.3.1.3 Routine Activities Impact Conclusions ...............................4-412

4.12.3.2 Impacts of an Accidental Fuel Spill........................................................4-412

4.12.3.3 Cumulative Impacts................................................................................4-412

4.12.3.3.1 OCS Program G&G Survey Activities.................................4-412

4.12.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-412

4.12.3.3.3 Cumulative Impact Conclusions .........................................4-413
xxiv Table of Contents

4.12.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures).............................................................................................4-413

4.12.4.1 Impacts of Routine Activities..................................................................4-413

4.12.4.1.1 Coastal Waters Seasonal Restrictions (February 1 to 

May 31)...............................................................................4-413

4.12.4.1.2 Routine Activities Impact Conclusions ...............................4-414

4.12.4.2 Impacts of an Accidental Fuel Spill........................................................4-414

4.12.4.3 Cumulative Impacts................................................................................4-414

4.12.4.3.1 OCS Program G&G Survey Activities.................................4-414

4.12.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-414

4.12.4.3.3 Cumulative Impact Conclusions .........................................4-414

4.12.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-415

4.12.5.1 Impacts of Routine Activities..................................................................4-415

4.12.5.2 Impacts of an Accidental Fuel Spill........................................................4-415

4.12.5.3 Cumulative Impacts................................................................................4-415

4.12.5.3.1 OCS Program G&G Survey Activities.................................4-415

4.12.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-415

4.12.5.3.3 Cumulative Impact Conclusions .........................................4-415

4.12.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-416

4.12.6.1 Impacts of Routine Activities..................................................................4-416

4.12.6.2 Impacts of an Accidental Fuel Spill........................................................4-416

4.12.6.3 Cumulative Impacts................................................................................4-417

4.12.6.3.1 OCS Program G&G Survey Activities.................................4-417

4.12.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-417

4.12.6.3.3 Cumulative Impact Conclusions .........................................4-417

4.12.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-417

4.12.7.1 Impacts of Routine Activities..................................................................4-417

4.12.7.2 Impacts of an Accidental Fuel Spill........................................................4-418

4.12.7.3 Cumulative Impacts................................................................................4-418

4.12.7.3.1 OCS Program G&G Survey Activities.................................4-418

4.12.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-418

4.12.7.3.3 Cumulative Impact Conclusions .........................................4-419

4.12.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-419

4.12.9 Summary Conclusion ............................................................................................4-419

4.13 Human Resources, Land Use, and Economics ................................................................4-420

4.13.1 Description of the Affected Environment...............................................................4-420

4.13.1.1 Land Use and Coastal Infrastructure.....................................................4-420

4.13.1.2 Environmental Justice............................................................................4-421
Gulf of Mexico G&G Activities Programmatic EIS xxv

4.13.1.3 Demographics........................................................................................4-422

4.13.1.4 Regional Economic Factors...................................................................4-423

4.13.2 Impacts – Alternative A (Pre-Settlement [June 2013] Alternative.........................4-425

4.13.2.1 Impacts of Routine Events.....................................................................4-426

4.13.2.1.1 Land Use and Coastal Infrastructure..................................4-426

4.13.2.1.2 Environmental Justice.........................................................4-427

4.13.2.1.3 Demographics.....................................................................4-427

4.13.2.1.4 Regional Economic Factors................................................4-428

4.13.2.2 Impacts of an Accidental Spill................................................................4-429

4.13.2.3 Cumulative Impacts................................................................................4-429

4.13.2.3.1 OCS Program G&G Survey Activities.................................4-429

4.13.2.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-430

4.13.2.3.3 Cumulative Impact Conclusions .........................................4-436

4.13.3 Impacts – Alternative B (Settlement Agreement Alternative)................................4-436

4.13.3.1 Impacts of Routine Events.....................................................................4-436

4.13.3.1.1 Land Use and Coastal Infrastructure..................................4-436

4.13.3.1.2 Environmental Justice.........................................................4-437

4.13.3.1.3 Demographics.....................................................................4-437

4.13.3.1.4 Regional Economic Factors................................................4-437

4.13.3.2 Impacts of an Accidental Spill................................................................4-440

4.13.3.3 Cumulative Impacts................................................................................4-440

4.13.3.3.1 OCS Program G&G Survey Activities.................................4-440

4.13.3.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-440

4.13.3.3.3 Cumulative Impact Conclusions .........................................4-440

4.13.4 Impacts – Alternative C (Proposed Action – Alternative A Plus Additional 

Mitigation Measures).............................................................................................4-441

4.13.4.1 Impacts of Routine Activities..................................................................4-441

4.13.4.1.1 Land Use and Coastal Infrastructure..................................4-441

4.13.4.1.2 Environmental Justice.........................................................4-441

4.13.4.1.3 Demographics.....................................................................4-442

4.13.4.1.4 Regional Economic Factors................................................4-442

4.13.4.2 Impacts of an Accidental Spill................................................................4-444

4.13.4.3 Cumulative Impacts................................................................................4-444

4.13.4.3.1 OCS Program G&G Survey Activities.................................4-444

4.13.4.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-445

4.13.4.3.3 Cumulative Impact Conclusions .........................................4-445

4.13.5 Impacts – Alternative D (Alternative C Plus Marine Mammal Shutdowns)...........4-445

4.13.5.1 Impacts of Routine Events.....................................................................4-445

4.13.5.1.1 Land Use and Coastal Infrastructure..................................4-445

4.13.5.1.2 Environmental Justice.........................................................4-446
xxvi Table of Contents

4.13.5.1.3 Demographics.....................................................................4-446

4.13.5.1.4 Regional Economic Factors................................................4-446

4.13.5.2 Impacts of an Accidental Spill................................................................4-448

4.13.5.3 Cumulative Impacts................................................................................4-449

4.13.5.3.1 OCS Program G&G Survey Activities.................................4-449

4.13.5.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-449

4.13.5.3.3 Cumulative Impact Conclusions .........................................4-449

4.13.6 Impacts – Alternative E (Alternative C at Reduced Activity Levels) .....................4-449

4.13.6.1 Impacts of Routine Events.....................................................................4-449

4.13.6.1.1 Land Use and Coastal Infrastructure..................................4-449

4.13.6.1.2 Environmental Justice.........................................................4-450

4.13.6.1.3 Demographics.....................................................................4-450

4.13.6.1.4 Regional Economic Factors................................................4-451

4.13.6.2 Impacts of an Accidental Spill................................................................4-453

4.13.6.3 Cumulative Impacts................................................................................4-453

4.13.6.3.1 OCS Program G&G Survey Activities.................................4-453

4.13.6.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-454

4.13.6.3.3 Cumulative Impact Conclusions .........................................4-454

4.13.7 Impacts – Alternative F (Alternative C Plus Area Closures).................................4-454

4.13.7.1 Impacts of Routine Events.....................................................................4-454

4.13.7.1.1 Land Use and Coastal Infrastructure..................................4-454

4.13.7.1.2 Environmental Justice.........................................................4-455

4.13.7.1.3 Demographics.....................................................................4-455

4.13.7.1.4 Regional Economic Factors................................................4-455

4.13.7.2 Impacts of an Accidental Spill................................................................4-458

4.13.7.3 Cumulative Impacts................................................................................4-458

4.13.7.3.1 OCS Program G&G Survey Activities.................................4-458

4.13.7.3.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-458

4.13.7.3.3 Cumulative Impact Conclusions .........................................4-458

4.13.8 Impacts – Alternative G (No New Activity Alternative)..........................................4-459

4.13.8.1 Land Use and Coastal Infrastructure.....................................................4-459

4.13.8.2 Environmental Justice............................................................................4-459

4.13.8.3 Demographics........................................................................................4-459

4.13.8.4 Regional Economic Factors...................................................................4-460

4.13.8.5 Cumulative Impacts................................................................................4-462

4.13.8.5.1 OCS Program G&G Survey Activities.................................4-462

4.13.8.5.2 Activities Other Than OCS Program G&G Survey 

Activities..............................................................................4-462

4.13.8.5.3 Cumulative Impact Conclusions .........................................4-462

4.13.9 Summary Conclusion ............................................................................................4-462
Gulf of Mexico G&G Activities Programmatic EIS xxvii

5 OTHER NEPA CONSIDERATIONS............................................................................................... 5-3

5.1 Unavoidable Adverse Impacts of the Proposed Action......................................................... 5-3

5.2 Irreversible and Irretrievable Commitment of Resources...................................................... 5-4

5.3 Relationship Between Short-Term Uses of the Environment and the Maintenance and 

Enhancement of Long-Term Productivity.............................................................................. 5-5

6 PUBLIC INVOLVEMENT AND AGENCY CONSULTATION AND COORDINATION ................... 6-3

6.1 Development of the Proposed Action.................................................................................... 6-3 

6.2 Notice of Intent....................................................................................................................... 6-3 

6.3 Scoping and Development of the Draft Programmatic EIS................................................... 6-3

6.3.1 Scoping Meetings...................................................................................................... 6-4 

6.3.2 Comments Received During Scoping ....................................................................... 6-4 

6.3.3 Cooperating Agencies ............................................................................................... 6-5 

6.3.3.1 Bureau of Safety and Environmental Enforcement ................................... 6-6 

6.3.3.2 National Oceanic and Atmospheric Administration ................................... 6-7

6.4 Distribution of the Draft Programmatic EIS for Review and Comment ................................. 6-8 

6.5 Public Meetings.................................................................................................................... 6-12

6.6 Development of the Final Programmatic EIS...................................................................... 6-13

6.6.1 Major Differences Between the Draft and Final Programmatic EISs...................... 6-13

6.6.2 Record of Decision .................................................................................................. 6-13

6.7 Comments Received on the Draft Programmatic EIS......................................................... 6-13

6.8 Regulatory Framework ........................................................................................................ 6-14

6.8.1 Coastal Zone Management Act............................................................................... 6-14

6.8.2 Endangered Species Act......................................................................................... 6-16

6.8.3 Magnuson-Stevens Fishery Conservation and Management Act .......................... 6-16

6.8.4 National Historic Preservation Act........................................................................... 6-17

6.8.5 National Marine Sanctuaries Act............................................................................. 6-18

6.8.6 Department of Defense ........................................................................................... 6-18

6.8.7 Government-to-Government Tribal Consultation.................................................... 6-18

7 LITERATURE CITED...................................................................................................................... 7-3

8 PREPARERS AND REVIEWERS .................................................................................................. 8-3

8.1 BOEM, BSEE, and NMFS Preparers .................................................................................... 8-3 

8.2 BOEM, BSEE, and NMFS Reviewers ................................................................................... 8-3 

8.3 Contractor Preparers ............................................................................................................. 8-5

9 GLOSSARY .................................................................................................................................... 9-3 
xxviii Table of Contents

Volume II 

Page

LIST OF FIGURES............................................................................................................................. xxix 

LIST OF TABLES............................................................................................................................... xxxi

FIGURES ................................................................................................................................. Figures-3 

TABLES......................................................................................................................................Tables-3 

KEYWORD INDEX................................................................................................................Keywords-3 

APPENDIX A AGREEMENTS AND COOPERATING AGENCY LETTERS................................... A-3 

APPENDIX B PROTECTIVE MEASURES AND MITIGATION AND REGULATORY 

REQUIREMENTS..................................................................................................... B-1 

APPENDIX C SETTLEMENT AGREEMENT AND STIPULATION TO AMEND SETTLEMENT 

AGREEMENT ........................................................................................................... C-3 

APPENDIX D ACOUSTIC PROPAGATION AND EXPOSURE MODELING ................................. D-1 

Volume III

Page

LIST OF FIGURES............................................................................................................................. xxix 

LIST OF TABLES............................................................................................................................... xxxi

APPENDIX E EXPANDED AFFECTED ENVIRONMENT INFORMATION.................................... E-3 

APPENDIX F G&G SURVEY DESCRIPTIONS.............................................................................. F-1 

APPENDIX G SCREENING OUT TEAM REPORT......................................................................... G-1 

APPENDIX H MARINE MAMMAL HEARING AND SENSITIVITY TO ACOUSTIC IMPACTS....... H-1 

APPENDIX I SEA TURTLE HEARING AND SENSITIVITY TO ACOUSTIC IMPACTS ................. I-1 

APPENDIX J FISH HEARING AND SENSITIVITY TO ACOUSTIC IMPACTS .............................. J-1 

APPENDIX K CUMULATIVE AND CHRONIC EFFECTS IN THE GULF OF MEXICO ................. K-1 

APPENDIX L PANEL REPORTS..................................................................................................... L-1 

Volume IV

Page

LIST OF FIGURES............................................................................................................................. xxix 

LIST OF TABLES............................................................................................................................... xxxi

APPENDIX M RESPONSES TO PUBLIC COMMENTS ON THE DRAFT GULF OF MEXICO 

G&G PROGRAMMATIC EIS .................................................................................... M-3 

APPENDIX N PROPAGATION AND EXPOSURE MODELING IN THE GULF OF MEXICO........ N-1 
Gulf of Mexico G&G Activities Programmatic EIS xxix

LIST OF FIGURES

Page

Figure ES-1. Area of Interest for the Proposed Action.................................................................... ix

Figure 1.1-1. Area of Interest for the Proposed Action....................................................... Figures-3 

Figure 1.2-1. Comparison of the M-Weighting Curves for the 2012 Criteria and the 

July 2016 New Acoustic Criteria. .................................................................. Figures-4 

Figure 2.2-1. Alternative B Seasonal Restrictions for Coastal Waters and Areas of 

Concern as Defined in the Settlement Agreement. ...................................... Figures-5 

Figure 2.3-1. Alternatives C through F Seasonal Restrictions for Coastal Waters 

Between February 1 and May 31 and Areas Requiring Passive Acoustic 

Monitoring (PAM) for All Seismic Airgun Surveys. ....................................... Figures-6 

Figure 2.8-1. Alternative F Closure Areas (the Central Planning Area Closure Area; 

the Eastern Planning Area Closure Area; the Dry Tortugas Closure Area; 

and the Flower Gardens Closure Area) and Seasonal Restrictions for 

Coastal Waters Between February 1 and May 31 and Areas Requiring 

Passive Acoustic Monitoring for All Seismic Airgun Surveys. ...................... Figures-7 

Figure 3.4-1. Cumulative Activities Occurring in the Area of Interest................................. Figures-8 

Figure 4.2-1. Locations of Selected Northern Gulf of Mexico Cetacean Stocks in 

Relation to the Cumulative Surface Oiling Footprint of the Deepwater 

Horizon Oil Spill............................................................................................. Figures-9 

Figure 4.2-2. Distribution of Sperm Whale Sightings........................................................ Figures-10

Figure 4.2-3. Distribution of Bryde’s Whale Sightings ...................................................... Figures-11

Figure 4.2-4. Bays and Sounds of the Northern Gulf of Mexico....................................... Figures-12

Figure 4.3-1. Location of the Four Recovery Units for the Loggerhead Turtle in the 

U.S............................................................................................................... Figures-13

Figure 4.3-2. Designated Critical Habitat for Hatchling Loggerhead Turtles, Including 

Sargassum Habitat...................................................................................... Figures-14

Figure 4.3-3. Sea Turtle Nesting Locations Reported for Individual Counties Adjacent 

to the Area of Interest from 1992 to 2014................................................... Figures-15

Figure 4.3-4. Frequency Range of Hearing in Sea Turtles and Typical Frequency 

Output from Seismic Airguns ...................................................................... Figures-16

Figure 4.4-1. Smalltooth Sawfish and Gulf Sturgeon Critical Habitat in the Area 

of Interest .................................................................................................... Figures-17

Figure 4.5-1. Distribution of Known Hard/Live Bottom and Chemosynthetic 

Communities Locations in the Area of Interest for Which Notices to 

essees and Operators Apply....................................................................... Figures-18

Figure 4.5-2. Topographic Features Located in the Area of Interest ............................... Figures-19

Figure 4.5-3. Location of Artificial Reefs (deliberately placed objects/structures 

of human origin) in the Area of Interest ...................................................... Figures-20

Figure 4.6-1. Mississippi Flyway Migratory Routes .......................................................... Figures-21

Figure 4.6-2. Bird Conservation Regions.......................................................................... Figures-22
xxx List of Figures

Figure 4.6-3. U.S. Important Bird Areas ........................................................................... Figures-23

Figure 4.6-4. Important Bird Areas of Louisiana that Include Nearshore Waters 

Within the Area of Interest. ......................................................................... Figures-24

Figure 4.7-1. National System Offshore Marine Protected Areas (MPAs) Within the 

Area of Interest........................................................................................... Figures-25 

Figure 4.7-2. National System Coastal Marine Protected Areas Within the Area of 

Interest ........................................................................................................ Figures-26

Figure 4.9-1. Locations of Selected Seasonal and/or Area Closures to Commercial 

Fishing in the Area of Interest..................................................................... Figures-27

Figure 4.12-1. Aids to Navigation, Shipping Lanes, Precaution Areas, Fairways, and 

Traffic Separation Schemes in the Area of Interest.................................... Figures-28

Figure 4.12-2. Military Use and Ordnance Disposal Areas in the Area of Interest ............ Figures-29

Figure 4.12-3. Outer Continental Shelf Sand and Gravel Borrow Areas Within the 

Area of Interest............................................................................................ Figures-30

Figure 4.12-4. Ocean Dredged Material Disposal Sites in the Area of Interest ................. Figures-31

Figure 4.12-5. Gulf of Mexico Energy Security Act (GOMESA) Areas............................... Figures-32

Figure 4.12-6a. Oil and Gas Platforms and Pipelines in the Western Planning Area 

in the Area of Interest.................................................................................. Figures-33

Figure 4.12-6b. Oil and Gas Platforms and Pipelines in the Central Planning Area 

in the Area of Interest.................................................................................. Figures-34

Figure 4.12-6c. Oil and Gas Platforms and Pipelines in the Eastern Planning Area 

in the Area of Interest.................................................................................. Figures-35

Figure 4.12-7. Existing Submarine Telecommunications Cables Located in the Area 

of Interest .................................................................................................... Figures-36
Gulf of Mexico G&G Activities Programmatic EIS xxxi

LIST OF TABLES

Page

Table ES-1. Applicability of Mitigation Measures to G&G Surveys by Alternative........................... xii 

Table ES-2. Preliminary Screening of Potential Impacts (Leopold Matrix)...................................... xv 

Table ES-3. Impact Levels by Resource and Applicable Impact-Producing Factor Across 

Alternatives A Through G, as Discussed in Chapter 2.13 .........................................xviii

Table ES-4. Impact Levels for Marine Mammals from Airguns and the Species Groups 

Protected Across Alternatives A through G, as Discussed in Chapters 2.13 

and 4.2......................................................................................................................... xxii 

Table 1.1-1. Federal Regulations Applicable to Pre-Lease and Post-Lease Activities 

by Mineral Resource of Interest .........................................................................Tables-3 

Table 1.1-2. Program Area, Geological and Geophysical Activity, Permitting Authority, 

and Typical National Environmental Protection Agency Action.........................Tables-5 

Table 1.2-1. Modeled and New Acoustic Guideline Criteria for Pulsed Sources...................Tables-6 

Table 1.2-2. Modeled and New Acoustic Guideline Criteria for Non-Impulsive Sources.......Tables-6 

Table 2.2-1. Applicability of Mitigation Measures to Geological and Geophysical Surveys 

by Alternative......................................................................................................Tables-7 

Table 2.2-2. Summary of Mitigation Measures Included in Alternatives A through G ...........Tables-8 

Table 2.7-1. Alternative E1: 10-Percent Reduction of Deep-Penetration Seismic, 

Multi-Client Surveys (in line miles) from the Maximum Projected Activity 

Levels of Geological and Geophysical Activities for Oil and Gas Exploration 

in the Area of Interest .......................................................................................Tables-13

Table 2.7-2. Alternative E2: 25-Percent Reduction of Deep-Penetration Seismic, 

Multi-Client Surveys (in line miles) from the Maximum Projected Activity 

Levels of Geological and Geophysical Activities for Oil and Gas Exploration 

in the Area of Interest .......................................................................................Tables-15

Table 2.9-1. Alternative G, the No New Activity Alternative: Projected Activity Levels 

of Geological and Geophysical Activities in the Area of Interest Over the 

10-Year Period..................................................................................................Tables-17

Table 2.13-1. Impact Levels by Resource and Applicable Impact-Producing Factors 

Across Alternatives A through G, as Discussed in Chapter 2.13.....................Tables-18

Table 2.13-2. Impact Levels for Marine Mammals from Airguns and Those Species 

Groups Protects Across Alternatives A through G, as Discussed in 

Chapter 4.2.......................................................................................................Tables-22

Table 3.1-1. Types of Geological and Geophysical Activities Included in this 

Programmatic Environmental Impact Statement .............................................Tables-24

Table 3.2-1. Projected Range of Activity Levels of Acoustic Geophysical Activities 

for Oil and Gas Exploration in the Area of Interest Over the 10-Year Time 

Period (numbers of surveys) and Survey Line Distance (miles) ......................Tables-26
xxxii List of Tables

Table 3.2-2. Projected Activity Levels of Non-Acoustic and Geological Activities for Oil 

and Gas Exploration in the Area of Interest Over the 10-Year Time Period 

(numbers of surveys) and Survey Line Distance (miles) or Cores ..................Tables-29

Table 3.2-3. Projected Activity Levels of Geological and Geophysical Activities for 

Renewable Energy Site Characterization and Assessment in the Area of 

Interest Over the 10-Year Time Period ............................................................Tables-30

Table 3.2-4. Projected Activity Levels of Geological Surveys for Outer Continental 

Shelf Marine Minerals Projects in the Area of Interest Over the 10-Year 

Time Period ......................................................................................................Tables-31

Table 3.2-5. Projected Activity Levels of Geophysical Surveys for Marine Minerals 

Projects in the Area of Interest Over the 10-Year Time Period .......................Tables-32

Table 3.2-6. Characteristics of the Proposed Geological and Geophysical Activities 

Scenario in the Area of Interest Over the 10-Year Time Period ......................Tables-34

Table 3.2-7. Summary of All Projected Maximum Activity Levels of Geological and 

Geophysical Activities in the Area of Interest Over the 10-Year Time Period 

for the Oil and Gas, Renewable Energy, and Marine Minerals Program 

Areas (sum of survey activities from Tables 3.2-2 through 3.2-6) ...................Tables-38

Table 3.3-1. Impact-Producing Factor Descriptions .............................................................Tables-39

Table 3.3-2. Characteristics of Active Acoustic Sound Sources Included in the 

Proposed Action ...............................................................................................Tables-40

Table 3.4-1. Cumulative Scenario Activities that Include Coincident Impact-Producing 

Factors with the Proposed Action Geological and Geophysical Activities.......Tables-42

Table 3.4-2. Summary of Oil and Gas Exploration and Development Activities in the 

U.S. Gulf of Mexico Projected 10-Year Projections (based on 40-year 

projections) .......................................................................................................Tables-43

Table 3.4-3. Structure Removal Permit Applications on the Area of Interest, 2004 to 

2015..................................................................................................................Tables-44

Table 3.4-4. Structures Removed from the Area of Interest, 2004 to 2015 .........................Tables-44

Table 3.4-5. Summary of Annual Oil and Gas Production from State Waters of Several 

Gulf Coast States .............................................................................................Tables-45

Table 3.4-6. Summary of Deepwater Ports in the Area of Interest ......................................Tables-46

Table 3.4-7. Summary of Commercial Vessel Port Visits for Vessels >1,000 Gross 

Tons to Area of Interest Ports in 2012 .............................................................Tables-48

Table 3.4-8. Vessel Trips in the Area of Interest in 2012 Recorded by Vessels 

Equipped with Automatic Identifications Systems............................................Tables-49

Table 3.4-9. Cruise Ship Departures from Gulf of Mexico Ports by Year ............................Tables-50

Table 4.1-1. Types of Geological and Geophysical Activities by Survey Type and 

Associated Impact-Producing Factors Associated with Each Survey Type 

as Described in Appendix F .............................................................................Tables-51

Table 4.1-2. Preliminary Screening of Potential Impacts (Leopold Matrix)..........................Tables-53

Table 4.1-3. Length and Area of Oiling of State and Federal Lands along the Northern 

Gulf Coast Caused by the Deepwater Horizon Oil Spill...................................Tables-54

Table 4.2-1. Marine Mammals Potentially Occurring in the Area of Interest........................Tables-55
Gulf of Mexico G&G Activities Programmatic EIS xxxiii

Table 4.2-2. Stocks of Common Bottlenose Dolphins within the Area of Interest ...............Tables-60

Table 4.2-3. Generalized Marine Mammal Hearing Groups, Associated Auditory 

Bandwidths, and Marine Mammal Species Present in the Area of Interest.....Tables-61

Table 4.2-4. Dual Injury Criteria for Marine Mammals Exposed to Impulsive Noise Over 

a 24-Hour Period ..............................................................................................Tables-61

Table 4.2-5. Existing and Proposed Injury and Behavior Exposure Criteria for 

Cetaceans and Manatees Exposed to Pulsed Sounds....................................Tables-62

Table 4.2-6. Density Ratios for Each of the Modeling Zones and Seasonal Restrictions/ 

Closure Areas1 ................................................................................................. Tables-63

Table 4.3-1. Sea Turtles Occurring in the Area of Interest...................................................Tables-64

Table 4.4-1. Hard Bottom Species and Life Stages with Essential Fish Habitat Identified 

within the Area of Interest.................................................................................Tables-65

Table 4.4-2. Coastal Migratory Pelagic Species and Life Stages with Essential Fish 

Habitat Identified within the Area of Interest ....................................................Tables-72

Table 4.4-3. Highly Migratory Species and Life Stages with Essential Fish Habitat 

Identified within the Area of Interest................................................................. Tables-73

Table 4.4-4. Shark Species and Life Stages with Essential Fish Habitat Identified 

within the Area of Interest.................................................................................Tables-75

Table 4.5-1. Topographic Features (Banks) of the Gulf of Mexico ......................................Tables-77

Table 4.6-1. Families of Seabirds, Waterfowl, and Shorebirds Occurring in the Area 

of Interest..........................................................................................................Tables-78

Table 4.7-1. National System Marine Protected Areas Within or Partially Within the 

Area of Interest ................................................................................................. Tables-81

Table 4.9-1. 2014 Economic Impacts of the Gulf of Mexico Region Seafood Industry 

(thousands of dollars).......................................................................................Tables-86

Table 4.9-2. Total Landings and Landings of Key Species/Species Groups (thousands 

of pounds).........................................................................................................Tables-86

Table 4.9-3. Primary Commercial Fishing Methods, Target Species, Seasons, and 

General Areas Fished in the Gulf of Mexico ....................................................Tables-87

Table 4.9-4. Summary of Seasonal and/or Area Closures to Commercial Fishing in 

Federal Waters in the Gulf of Mexico...............................................................Tables-88

Table 4.10-1. 2014 Recreational Gulf of Mexico Fishing Effort by Mode (thousands of 

dollars and trips)...............................................................................................Tables-89

Table 4.10-2. Economic Impacts of Gulf of Mexico Recreational Fishing Expenditures 

(thousands of angular trips)..............................................................................Tables-89

Table 4.10-3. Gulf of Mexico Recreational Harvest and Release of Key Species and 

Species Groups (thousands of fish)................................................................. Tables-89

Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico ...........Tables-90

Table 4.12-1. Recent Marine Mineral Projects in Florida, Louisiana, and Mississippi...........Tables-99

Table 4.13-1. 2012 Economic Impact of the Gulf of Mexico on Coastal Communities..........Tables-99

Table 4.13-2. Population Living in Gulf of Mexico Coastal Watershed Communities 

(1970 to 2010) ..................................................................................................Tables-99
xxxiv List of Tables

Table 4.13-3. 2012 Minority Populations in Geographic Areas Associated with Ports 

Serving the Geological and Geophysical Industry in the Area of Interest ..... Tables-100

Table 4.13-4. 2012 Low-Income Populations in Geographic Areas Associated with Ports 

Serving the Geological and Geophysical Industry in the Area of Interest .....Tables-101

Table 4.13-5. Average Survey Incremental Cost and Percent Cost Change by 

Alternative.......................................................................................................Tables-102

Table 4.13-6. Total Discounted Survey Incremental Cost by Alternative from 

2018-2027.......................................................................................................Tables-103

Table 4.13-7. Percent Change in Operational Efficiency by Alternative ..............................Tables-104
FIGURES

Gulf of Mexico G&G Activities Programmatic EIS Figures-3

Figure 1.1-1. Area of Interest for the Proposed Action.
Figures-4 Figures

Figure 1.2-1. Comparison of the M-Weighting Curves for the 2012 Criteria and the July 2016 New 

Acoustic Criteria. 
Gulf of Mexico G&G Activities Programmatic EIS Figures-5

Figure 2.2-1. Alternative B Seasonal Restrictions for Coastal Waters and Areas of Concern as Defined in the Settlement Agreement.
Figures-6 Figures

Figure 2.3-1. Alternatives C through F Seasonal Restrictions for Coastal Waters Between February 1 and May 31 and Areas Requiring 

Passive Acoustic Monitoring (PAM) for All Seismic Airgun Surveys.
Gulf of Mexico G&G Activities Programmatic EIS Figures-7

Figure 2.8-1. Alternative F Closure Areas (the Central Planning Area Closure Area; the Eastern Planning Area Closure Area; the Dry 

Tortugas Closure Area; and the Flower Gardens Closure Area) and Seasonal Restrictions for Coastal Waters Between 

February 1 and May 31 and Areas Requiring Passive Acoustic Monitoring for All Seismic Airgun Surveys.
Figures-8 Figures

Figure 3.4-1. Cumulative Activities Occurring in the Area of Interest. (Panel A shows existing oil and gas infrastructure, a 

proposed renewable energy site, and marine mineral borrow areas. Panel B shows shipping fairways and lanes, 

major ports, submarine cables, and areas of high commercial fishing. Panel C shows military use areas. 

Panel D shows barrier islands where restoration projects are likely to occur and ocean dredged material sites. 

For a larger scale, refer to Figures 4.12-1 through 4.12-7.) 
Gulf of Mexico G&G Activities Programmatic EIS Figures-9

Figure 4.2-1. Locations of Selected Northern Gulf of Mexico Cetacean Stocks in Relation to the 

Cumulative Surface Oiling Footprint of the Deepwater Horizon Oil Spill (From: Deepwater 

Horizon Natural Resource Damage Assessment Trustees, 2015, 2016). (Thirteen stocks of 

common bottlenose dolphin, including bay, sound, and estuary stocks; coastal stocks; 

continental shelf stocks; and oceanic stocks overlapped with the oil footprint. In addition, 

18 other oceanic species of cetaceans are found within the oil footprint.) 
Figures-10 Figures

Figure 4.2-2. Distribution of Sperm Whale Sightings (From: Ocean Biogeographic Information System, 2014; Barkaszi et al., 2012). 
Gulf of Mexico G&G Activities Programmatic EIS Figures-11

.

Figure 4.2-3. Distribution of Bryde’s Whale Sightings (From: Rosel et al., 2016).
Figures-12 Figures

Figure 4.2-4. Bays and Sounds of the Northern Gulf of Mexico. (Numbered areas correspond to the National Marine Fisheries Service, 

Southeast Fisheries Science Center’s logistical aerial survey areas and habitats for the 31 northern Gulf of Mexico bay, 

sound, and estuary stocks of common bottlenose dolphins listed in Table 4.2-2.) (From: Waring et al., 2016).
Gulf of Mexico G&G Activities Programmatic EIS Figures-13

Figure 4.3-1. Location of the Four Recovery Units for the Loggerhead Turtle in the U.S. (NRU = Northern Recovery Unit, 

PFRU = Peninsular Florida Recovery Unit, DTRU = Dry Tortugas Recovery Unit, NGMRU = Northern Gulf of 

Mexico Recovery Unit) (From: USDOC, NMFS and USDOI, FWS, 2008). (The Fifth Recovery Unit is composed of 

all nesting assemblages of loggerhead turtles within the greater Caribbean, outside the U.S.) 
Figures-14 Figures

Figure 4.3-2. Designated Critical Habitat for Hatchling Loggerhead Turtles, Including Sargassum Habitat (From: Federal Register, 2014b).
Gulf of Mexico G&G Activities Programmatic EIS Figures-15

Figure 4.3-3. Sea Turtle Nesting Locations Reported for Individual Counties Adjacent to the Area of Interest from 1992 to 2014 (refer to 

Table 4.3-1).
Figures-16 Figures

Figure 4.3-4. Frequency Range of Hearing in Sea Turtles and Typical Frequency Output from Seismic Airguns (Data from: Bartol et al., 

1999; Bartol and Ketten, 2006; Dow Piniak et al., 2012a,b; Martin et al., 2012a,b; Lavender et al., 2014). (Hearing data have 

not been collected from sea turtles at frequencies below 50 Hz.) 
Gulf of Mexico G&G Activities Programmatic EIS Figures-17

Figure 4.4-1. Smalltooth Sawfish and Gulf Sturgeon Critical Habitat in the Area of Interest (From: Federal Register, 2002b, 2009a).
Figures-18 Figures

Figure 4.5-1. Distribution of Known Hard/Live Bottom and Chemosynthetic Communities Locations in the Area of Interest for Which Notices

to Lessees and Operators Apply (From: Marine Cadastre, 2015).
Gulf of Mexico G&G Activities Programmatic EIS Figures-19

Figure 4.5-2. Topographic Features Located in the Area of Interest (From: Marine Cadastre, 2015).
Figures-20 Figures

Figure 4.5-3. Location of Artificial Reefs (deliberately placed objects/structures of human origin) in the Area of Interest. (The sizes of the 

artificial structures are not to scale and appear larger than they are to aid visual presentation.) (From: Marine Cadastre, 2015).
Gulf of Mexico G&G Activities Programmatic EIS FiguresFigure 4.6 21

-1. Mississippi Flyway Migratory Routes (From: Nutty Birdwatcher, 2015).
Figures-22 Figures

Figure 4.6-2. Bird Conservation Regions (From: USDOI, FWS, 2008a).
Gulf of Mexico G&G Activities Programmatic EIS FiguresFigure 4.6 23

-3. U.S. Important Bird Areas (From: National Audubon Society, 2011).
Figures-24 Figures

Figure 4.6-4. Important Bird Areas of Louisiana that Include Nearshore Waters Within the Area of Interest (Data from: National Audubon 

Society, 2011).
Gulf of Mexico G&G Activities Programmatic EIS Figures-25

Figure 4.7-1. National System Offshore Marine Protected Areas (MPAs) Within the Area of Interest. (From: USDOC, NOAA, National MPA 

Center, 2014).
Figures-26 Figures

Figure 4.7-2. National System Coastal Marine Protected Areas Within the Area of Interest (From: USDOC, NOAA, National MPA Center, 

2014).
Gulf of Mexico G&G Activities Programmatic EIS Figures-27

Figure 4.9-1. Locations of Selected Seasonal and/or Area Closures to Commercial Fishing in the Area of Interest (From: Marine Cadastre, 

2015).
Figures-28 Figures

Figure 4.12-1. Aids to Navigation, Shipping Lanes, Precaution Areas, Fairways, and Traffic Separation Schemes in the Area of Interest

(From: Marine Cadastre, 2015).
Gulf of Mexico G&G Activities Programmatic EIS Figures-29

Figure 4.12-2. Military Use and Ordnance Disposal Areas in the Area of Interest (From: Marine Cadastre, 2015).
Figures-30 Figures

Figure 4.12-3. Outer Continental Shelf Sand and Gravel Borrow Areas Within the Area of Interest (From: Marine Cadastre, 2017).
Gulf of Mexico G&G Activities Programmatic EIS Figures-31

Figure 4.12-4. Ocean Dredged Material Disposal Sites in the Area of Interest (From: Marine Cadastre, 2015).
Figures-32 Figures

Figure 4.12-5. Gulf of Mexico Energy Security Act (GOMESA) Areas.
Gulf of Mexico G&G Activities Programmatic EIS Figures-33

Figure 4.12-6a. Oil and Gas Platforms and Pipelines in the Western Planning Area in the Area of 

Interest (From: Marine Cadastre, 2015).
Figures-34 Figures

Figure 4.12-6b. Oil and Gas Platforms and Pipelines in the Central Planning Area in the Area of Interest

(From: Marine Cadastre, 2015).
Gulf of Mexico G&G Activities Programmatic EIS Figures-35

Figure 4.12-6c. Oil and Gas Platforms and Pipelines in the Eastern Planning Area in the Area of 

Interest (From: Marine Cadastre, 2015).
Figures-36 Figures

Figure 4.12-7. Existing Submarine Telecommunications Cables Located in the Area of Interest (From: Marine Cadastre, 2015). 
TABLES

Gulf of Mexico G&G Activities Programmatic EIS Tables-3

Table 1.1-1. Federal Regulations Applicable to Pre-Lease and Post-Lease Activities by Mineral Resource of Interest (Modified from: Cameron 

and Matthews, 2016) 

Regulatory 

Citation Mineral Resource Description Activity Phase

30 CFR part 550

(30 CFR part 250)

Oil, Gas, and Sulfur 

(Oil, Gas, and Sulfur 

Operations on the 

OCS)

550.102 What does this part do? 

(a) 30 CFR part 550 contains the regulations of the BOEM Offshore program that govern 

oil, gas, and sulfur exploration, development, and production operations on the OCS. 

When you conduct operations on the OCS, you must submit requests, applications, and 

notices, or provide supplemental information for BOEM approval.

Post-lease 

or on-lease 

exploration 

and/or 

development

550.103 Where can I find more information about the requirements in this part? 

BOEM may issue NTLs that clarify, supplement, or provide more detail about certain 

requirements. NTLs may also outline what you must provide as required information in 

your various submissions to BOEM.

550.207 What ancillary activities may I conduct?

Before or after you submit an Exploration Plan, Development and Production Plan, or 

Development Operations Coordination Document to BOEM, you may elect, the 

regulations in this part may require, or the Regional Supervisor may direct you to conduct 

ancillary activities. Ancillary activities include the following:

(a) G&G explorations and development activities;

(b) Geological and high-resolution geophysical, geotechnical, archaeological, biological, 

physical oceanographic, meteorological, socioeconomic, or other surveys; or

(c) Studies that model potential oil and hazardous substance spills, drilling muds and 

cuttings discharges, projected air emissions, or potential hydrogen sulfide (H2S) releases.

30 CFR part 551

(30 CFR part 251)

Oil, Gas, and Sulfur 

(G&G Explorations of 

the OCS)

551.2 Purpose of this part

(a) To allow you to conduct G&G activities on the OCS related to oil, gas, and sulfur on 

unleased lands or on lands under lease to a third party.

Pre-lease or 

off-lease 

exploration 

or scientific 

research

551.3 Authority and applicability of this part

(a) This part does not apply to G&G exploration conducted by or on behalf of the lessee 

on a lease on the OCS. Refer to 30 CFR part 550 if you plan to conduct G&G activities 

related to oil, gas, or sulfur under terms of a lease. 

(b) Federal agencies are exempt from the regulations in this part. 

(c) G&G exploration or G&G scientific research related to minerals other than oil, gas,

and sulfur is covered by regulations at 30 CFR part 580.
Table 1.1-1. Federal Regulations Applicable to Pre-hxLease and Post-Lease Activities by Mineral Resource of Interest (continued)

Tables-4 Tables

Regulatory 

Citation Mineral Resource Description Activity Phase

30 CFR part 551

(30 CFR part 251)

(continued)

Oil, Gas, and Sulfur 

(G&G Explorations of 

the OCS) (continued)

551.4 Types of G&G activities that require permits or notices

(a) Exploration – You must have a BOEM-approved permit to conduct G&G exploration, 

including deep stratigraphic tests, for oil, gas, or sulfur resources. If you conduct both 

G&G exploration, you must have a separate permit for each. 

(b) Scientific research – You may only conduct G&G scientific research related to oil, 

gas, and sulfur on the OCS after you obtain a BOEM-approved permit or file a Notice.

30 CFR part 580a

(30 CFR part 280)

All Minerals Exclusive 

of Oil, Gas, and Sulfur 

(Prospecting for 

Minerals Other than 

Oil, Gas, and Sulfur 

on the OCS)

580.2 What is the purpose of this part? 

(a) Allow you to conduct prospecting activities or scientific research activities on the OCS 

in Federal waters related to hard minerals on unleased lands or on lands under lease to a 

third party. 

(b) Ensure that you carry out prospecting activities or scientific research activities in a 

safe and environmentally sound manner so as to prevent harm or damage to, or waste 

of, any natural resources (including any hard minerals in areas leased or not leased); any 

life (including fish and other aquatic life); property; or the marine, coastal, or human 

environment.

Pre-lease or 

off-lease 

prospecting

580.4 What activities are not covered by this part? 

(a) G&G prospecting activities conducted by, or on behalf of, the lessee on a lease on 

the OCS; 

(b) Federal agencies; 

(c) Post-lease activities for mineral resources other than oil, gas, and sulfur, which are 

covered by regulations at 30 CFR parts 582b and 282c

; and

(d) G&G exploration or G&G scientific research activities related to oil, gas, and sulfur, 

including gas hydrates, which are covered by regulations at 30 CFR parts 551 and 251.

580.10 What must I do before I may conduct prospecting activities? 

You must have a BOEM-approved permit to conduct G&G prospecting activities, 

including deep stratigraphic tests, for hard minerals. If you conduct both G&G 

prospecting activities, you must have a separate permit for each.

30 CFR part 585

Renewable Energy 

and Alternate Uses of 

Existing Facilities on 

the OCS

BOEM has developed guidelines for providing G&G, hazards, and archaeological 

information for renewable energy projects. The guidelines specify that BOEM 

recommends avoidance as a primary mitigation strategy.

Pre-lease 

and postlease

BOEM = Bureau of Ocean Energy Management; CFR = Code of Federal Regulations; G&G = geological and geophysical; NTL = Notice to Lessees and 

Operators; OCS = Outer Continental Shelf. a

30 CFR part 580 regulations apply only to G&G activities in support of competitive leasing. For noncompetitive leasing for public works, authorizations 

are issued pursuant to Section 11 of the Outer Continental Shelf Lands Act.

b

30 CFR part 582 – Operations of BOEM Issuance of Permits and Plans. c

30 CFR part 282 – Operations under a Mineral Lease under Provisions of Section 8(k) of the Outer Continental Shelf Lands Act.
Gulf of Mexico G&G Activities Programmatic EIS Tables-5 

Table 1.1-2. Program Area, Geological and Geophysical Activity, Permitting Authority, and Typical 

National Environmental Protection Agency Action

G&G Activity 

in Support of

On 

Lease

Off 

Lease 

and/or 

Third 

Party

Permitting 

Authority

How Approved

Typical 

NEPA 

Action OCS Plan1 Permit 

Application

Oil and Gas

Exploration 

(post-lease) X -- 30 CFR part 550 EP None EA or EIS

Development 

(post-lease) X -- 30 CFR part 550 DOCD or DPP None EA or EIS

Ancillary Activities 

(post-lease) X -- 30 CFR part 550

Conditional, 

Plan 

Revision

Notification Conditional, 

EA

Exploration 

(pre-lease) -- X 30 CFR part 551 None X EA or EIS

Scientific Research -- X 30 CFR part 551 None X EA

Renewable Energy

Site Assessment X -- 30 CFR part 585 SAP None EA or EIS

Renewable Energy 

Facility 

Development

X -- 30 CFR part 585 COP None EA or EIS

Other Activities X -- 30 CFR part 585 GAP None EA or EIS

Marine Minerals

Research and 

Prospecting -- X OCSLA Section 11

30 CFR part 5802 None Authorization 

or Notification EA or EIS

Leasing-Related 

Monitoring X --

OCSLA 

Section 8(k)

30 CFR parts 

581-5822

None None None3

CFR = Code of Federal Regulations; COP = Construction and Operations Plan; DOCD = Development 

Operations Coordination Document; DPP = Development and Production Plan; EA = environmental 

assessment; EIS = environmental impact statement; EP = Exploration Plan; G&G = geological and 

geophysical; GAP = General Activities Plan; NEPA = National Environmental Policy Act; OCS = Outer 

Continental Shelf; OCSLA = Outer Continental Shelf Lands Act; SAP = Site Assessment Plan.

X indicates required; -- indicates not required. 1 Plan types are defined in Chapters 3.2.1.1, 3.2.2.1, and 3.2.3.1. 2 Applies to competitive leasing only, which BOEM has never done for marine minerals.

3 Addressed in NEPA document for prospecting.
Tables-6 Tables

Table 1.2-1. Modeled and New Acoustic Guideline Criteria for Pulsed Sources

Functional Hearing Group

GOM Programmatic EIS 

Modeling New Criteria1 Difference

Energy Pressure Energy Pressure Energy Pressure

SEL

(dB re

1 μPa2·s)

SPLpeak

(dB re 

1 μPa)

LE, 24h

(dB re 

1 μPa2·s)

Lpk,flat 

(dB re 

1 μPa)

(dB) (dB)

Low-frequency cetaceans 192 230 183 219 -9 -11

Mid-frequency cetaceans 187 230 185 230 -2 0

High-frequency cetaceans 161 200 155 202 -6 +2

dB = decibel; dB re 1 μPa = decibels referenced to 1 micropascal; dB re 1 μPa2•s = decibels referenced 

to 1 micropascal per second; EIS = environmental impact statement; GOM = Gulf of Mexico; 

LE,24h = sound exposure level, cumulative 24 hours; Lpk, flat = peak sound pressure level (unweighted); 

SEL = sound exposure level; SPLpeak = peak sound pressure level.

1 USDOC, NMFS, 2016b. 

Note: The new criteria requires the summation of energy over 24 hours, which is different from the old 

criteria, which were based on the root mean square metric rather than cumulative sound 

exposure level.

Table 1.2-2. Modeled and New Acoustic Guideline Criteria for Non-Impulsive Sources

Functional Hearing Group

GOM Programmatic EIS 

Modeling New Criteria1 Difference

Energy Pressure Energy Pressure Energy Pressure

SEL

(dB re

1 μPa2·s)

SPLpeak

(dB re 

1 μPa)

LE,24h 

(dB re 

1 μPa2·s)

Generally 

not 

needed 

or used

(dB) (dB)

Low-frequency cetaceans 192 230 199 - +7 N/A

Mid-frequency cetaceans 187 230 198 - +11 N/A

High-frequency cetaceans 161 200 173 - +12 N/A

dB = decibel; dB re 1 μPa = decibels referenced to 1 micropascal; dB re 1 μPa2•s = decibels referenced 

to 1 micropascal per second; EIS = environmental impact statement; GOM = Gulf of Mexico; 

LE,24h = sound exposure level, cumulative 24 hours; SEL = sound exposure level; SPLpeak = peak sound 

pressure level.

1 USDOC, NMFS, 2016b. 

N/A = not applicable.

Note: The new criteria requires the summation of energy over 24 hours, which is different from the old 

criteria, which were based on the root mean square metric rather than cumulative sound 

exposure level.
Gulf of Mexico G&G Activities Programmatic EIS Tables-7 

Table 2.2-1. Applicability of Mitigation Measures to Geological and Geophysical Surveys by Alternative (indicates which mitigation measure is 

applicable to an alternative)

Survey Type

Mitigation Measures Survey 

Protocol

Seasonal Restrictions 

and Closures

Vessel Strike AvoidanceMarine Debris GuidanceAvoidance of Sensitive Benthic Communities Avoidance of Historic and Prehistoric Sites Shallow Hazards GuidanceNMS Regulations Military CoordinationAncillary Activity GuidanceImplement PSO ProgramImplement Expanded PSO ProgramMinimum Separation DistanceReduced Level of ActivityUse of PAM Strongly EncouragedUse of PAM RequiredSeismic Airgun Survey ProtocolNon-Airgun HRG Survey ProtocolCoastal Waters Seasonal Restriction

Areas of Concern within the Eastern Planning 

Area8

CP

A, EP

A, Dry Tortugas, and Flower Garden

Banks Closure Areas

Seismic Airgun Surveys A-G A-G A-G A-G1 A-G1 A-G A-G A-G A,G B- F2

D3 B E A,G B-F4C-F5 A-G -- B6C-F7 B F 

Non-airgun HRG Surveys 

with frequencies >200 kHz A-G A-G A-G A-G1 A-G1 A-G A-G -- -- -- -- -- -- -- -- -- -- -- --

Non-airgun HRG Surveys 

with frequencies ≤200 kHz A-G A-G A-G A-G1 A-G1 A-G A-G -- C-F -- -- -- -- -- -- C-F -- -- F 

Other G&G Surveys A-G A-G A-G A-G1 A-G1 A-G A-G -- -- -- -- -- -- -- -- -- -- -- --

CPA = Central Planning Area; EPA = Eastern Planning Area; ft = feet; HRG = high-resolution geophysical; kHz = kilohertz; m = meters; NMS = National Marine Sanctuary; 

PAM = passive acoustic monitoring; PSO = protected species observer. 1 Avoidance of historic and prehistoric sites and sensitive benthic communities applies only to surveys that involve seafloor disturbing activities. Seismic airgun surveys and nonairgun HRG surveys that do not disturb the seafloor are not required to avoid these sites or features. Non-airgun HRG surveys and most seismic airgun surveys (except those in 

which cables or sensors are placed in or on the seafloor) do not disturb the seafloor. 2 Expanded to include manatees and all water depths.

3 Expanded from footnote 2 to include shutdown for all marine mammals, with the exception of bow-riding or actively approaching dolphins (i.e., common bottlenose, Fraser’s, 

Clymene’s, rough-toothed, striped, spinner, Atlantic spotted, pantropical, and Risso’s) and all water depths. 4 During periods of reduced visibility for surveys in waters deeper than 100 m (328 ft).

5 PAM required for all airgun surveys at all times in the Mississippi Canyon and De Soto Canyon lease blocks.

6 Applies to Federal coastal waters shoreward of the 20-m (66-ft) and a 5-km (3-mi) buffer extending seaward from the 20-m (66-ft) isobath between January 1 and April 30. 7 Applies to all coastal waters shoreward of the 20-m (66-ft) isobath between February 1 and May 31. 8 Does not apply to currently leased blocks, any portion of the area encompassed by Lease Sale 224, or neighboring blocks adjacent to permitted survey areas but within an 

otherwise off-limit area.
Tables-8 Tables

Table 2.2-2. Summary of Mitigation Measures Included in Alternatives A through G 

Measure Summarized Description Alternative

A B C D E F G

Guidance for Vessel Strike 

Avoidance 

(NTL 2012-JOINT-G01)

All authorizations for shipboard surveys, regardless of 

vessel size, would include guidance for vessel strike 

avoidance while a vessel is in transit. The guidance would 

address protected species identification, vessel strike 

avoidance, and injured/dead protected species reporting in 

accordance with NMFS’ Compliance Guide for the Right 

Whale Ship Strike Reduction Rule.

Yes Yes Yes Yes Yes Yes Yes

Guidance for Marine Debris 

Awareness 

(NTL 2015-BSEE-G03)

All authorizations for shipboard surveys would include 

guidance for marine debris awareness, highlighting the 

environmental and socioeconomic impacts of marine trash 

and debris, as well as operator responsibilities for ensuring 

that trash and debris are not discharged into the marine 

environment.

Yes Yes Yes Yes Yes Yes Yes

Guidance for Avoidance of 

Biologically Sensitive Underwater 

Features and Areas (NTL 2009-

G39) and Deepwater (Sensitive) 

Benthic Communities (NTL 2009-

G40)

All authorizations for seafloor-disturbing activities would be 

subject to restrictions to protect sensitive benthic 

communities (e.g., topographic features, hard/live bottom 

areas, deepwater coral communities, chemosynthetic 

communities). In areas where these communities are 

known or suspected, authorizations may include 

requirements for mapping and avoidance, as well as predeployment photographic surveys where bottom-founded 

equipment is to be deployed.

Yes Yes Yes Yes Yes Yes Yes

Guidance for Archaeological 

Resources 

(NTLs 2005-G07, 2005 A03, 

2008-G20, and 2011-JOINT-G01)

Authorizations for seafloor-disturbing activities would include 

requirements for operators to report suspected historic and 

prehistoric archaeological resources to BOEM and to take 

precautions to protect the resource. There are reporting and 

avoidance requirements for any previously undiscovered or 

suspected archaeological resource.

Yes Yes Yes Yes Yes Yes Yes

Guidance for shallow hazards 

program 

(NTLs 2008-G05 and 2014 G03)

All seafloor-disturbing activities associated with exploration, 

development, production, and transportation operations 

must be preceded by a shallow hazards assessment.

Yes Yes Yes Yes Yes Yes Yes
Table 2.2-2. Summary of Mitigation Measures Included in Alternatives A through G (continued)

Gulf of Mexico G&G Activities Programmatic EIS Tables-9 

Measure Summarized Description Alternative

A B C D E F G

Regulations for Activities In or Near 

National Marine Sanctuaries 

(NMSs) (15 CFR part 922)

BOEM would not authorize seafloor-disturbing activities 

within an NMS no-activity zone. Seafloor-disturbing activities 

within the Flower Garden Banks NMS and outside of a 

no-activity zone are prohibited except for necessary activities 

conducted incidental to exploration for, development of, or 

production of oil and gas in those areas. Seafloor-disturbing 

activities proposed near the boundaries of an NMS would be 

assigned a setback distance by BOEM in consultation with 

the Sanctuary Manager.

Yes Yes Yes Yes Yes Yes Yes

Guidance for Military Coordination 

(NTL 2014-G04)

To ensure personnel safety and reduce the likelihood of 

conflicts between military and OCS operations, all 

authorizations will include requirements in which the lessee 

or designated operator must enter into an agreement with the 

appropriate individual military command headquarters 

concerning the control of electromagnetic emissions and use 

of boats and aircraft in the applicable warning area or water 

test area before commencing such traffic.

Yes Yes Yes Yes Yes Yes Yes

Guidance for Ancillary Activities 

(NTL 2009-G34)

All authorizations for ancillary G&G exploration or 

development activities require notification 15 or 30 days prior 

to commencement of operations, depending on the type of 

survey, equipment, location, and water depth.

Yes Yes Yes Yes Yes Yes Yes

Minimum Separation Distances

When in the AOCs, simultaneous deep-penetration seismic 

airgun surveys shall maintain a separation distance of 40 km 

(25 mi) between active sources. When outside the AOCs, 

the separation distance will be 30 km (19 mi), excluding 

multiple ships operating in a coordinated survey (e.g., WAZ 

surveys) or due to safety or weather conditions.

No Yes No No No No No

Seismic Restriction in Eastern 

Planning Area

Deep-penetration seismic airgun surveys shall not be 

conducted within the portion of the AOCs within the EPA. 

This restriction does not apply to currently leased blocks, any 

portion of the area encompassed by Lease Sale 224, or 

neighboring blocks adjacent to permitted survey areas but 

within an otherwise off-limit area.

No Yes No No No No No
Table 2.2-2. Summary of Mitigation Measures Included in Alternatives A through G (continued)

Tables-10 Tables

Measure Summarized Description Alternatives

A B C D E F G

Seismic Airgun Survey Protocol: PSO and PAM Programs

− Implementation of Seismic 

Survey Mitigation Measures 

and PSO Program 

(NTL 2012-JOINT-G02)

All authorizations for seismic airgun surveys in water 

depths >200 m (656 ft) in the WPA and CPA and in 

all water depths in the EPA would include ramp-up, 

protected species observers with specified training, 

visual and passive acoustic monitoring, exclusion 

zones, and reporting protocols for protected species.

Yes Yes Yes Yes Yes Yes Yes

− Expanded PSO Program 

(manatees and all water 

depths)

The PSO Program would be expanded to include 

manatees as well as whales (whales are defined as 

all marine mammals in the Gulf of Mexico except 

dolphins and manatees; dolphins are defined as all 

marine mammal species in the family Delphinidae, 

which includes killer whales, pilot whales, and all of 

the dolphin species). Operators will immediately 

shut down all airguns and cease seismic operations 

any time a whale or manatee is detected entering or 

within the exclusion zone. Operators may 

recommence seismic operations and ramp-up of 

airguns only when the exclusion zone has been 

visually inspected for at least 30 minutes to ensure 

the absence of whales, sea turtles, and manatees. 

Further, the PSO Program would apply to all 

authorizations for deep-penetration seismic airgun 

surveys in the AOI regardless of water depth.

No Yes Yes Yes Yes Yes No
Table 2.2-2. Summary of Mitigation Measures Included in Alternatives A through G (continued)

Gulf of Mexico G&G Activities Programmatic EIS Tables-11

Measure Summarized Description Alternative

A B C D E F G

− Expanded PSO Program 

(non-bow-riding Delphinids) 

The PSO Program would be expanded to require 

shutdowns for all marine mammals in the exclusion 

zone (i.e., whales, manatees, and dolphins (refer to 

the definitions above) with the exception of bowriding dolphins (i.e., common bottlenose, Fraser’s, 

Clymene’s, rough-toothed, striped, spinner, Atlantic 

spotted, pantropical, and Risso’s).

No No No Yes No No No

− PAM Program

Monitoring for whales with PAM will allow ramp-up 

during times of reduced visibility when ramp-up 

would not be permitted otherwise. An assessment of 

the use of PAM, a description of the PAM system, 

the software used, and the Monitoring Plan should 

be reported to BSEE at the beginning of PAM use. 

The use of PAM is strongly encouraged.

Yes Yes Yes Yes Yes Yes Yes

− Expanded PAM Requirement

(low visibilty) 

The use of PAM is required during periods of 

reduced visibility for deep-penetration seismic airgun 

surveys occurring in water depths >100 m (328 ft).

No Yes Yes Yes Yes Yes No

− Expanded PAM Requirement

(canyons)

In addition to the above, PAM is required at all times

for seismic airgun surveys in Mississippi Canyon and 

De Soto Canyon lease blocks.

No No Yes Yes Yes Yes No

Seasonal Restrictions for 

Federal Coastal Waters

The permittee shall not operate any airguns or airgun 

arrays in Federal coastal waters of the AOI from the 

20-m (66-ft) isobath to the State-Federal boundary 

and a 5-km (3-mi) buffer extending seaward from the 

20-m (66-ft) isobath between January 1 and April 30.

No Yes No No No No No

Seasonal Restrictions for All 

Coastal Waters

The permittee shall not operate any airguns or airgun 

arrays in coastal waters of the AOI from the 20-m 

(66-ft) isobath to shore between February 1 and 

May 31.

No No Yes Yes Yes Yes No
Table 2.2-2. Summary of Mitigation Measures Included in Alternatives A through G (continued)

Tables-12 Table

s

Measures Summarized Description Alternative

A B C D E F G

HRG Survey Protocol

Authorizations for HRG non-airgun surveys in which 

one or more active acoustic sound sources will be 

operating at frequencies <200 kHz will require a 

30-minute, pre survey clearance period of marine 

mammals and sea turtles before start-up or after a 

shutdown for all marine mammals except dolphins 

that are within the exclusion zone. One PSO and a 

200-m (656-ft) exclusion zone are required in all 

water depths throughout the AOI. Authorizations for 

an HRG airgun survey require use of seismic airgun 

survey protocols described under Alternative A.

No No Yes Yes Yes Yes No

Reduction of G&G Activity 

Levels

Decrease the amount of deep-penetration, seismic 

multi-client surveys (in line miles) by 10 or 

25 percent from estimated levels in a calendar year.

No No No No Yes No No

Area Closures

Closure of four areas: CPA Closure Area; EPA 

Closure Area; Dry Tortugas Closure Area; and 

Flower Gardens Closure Area. Areas are closed to 

all activities except HRG non-airgun surveys with 

equipment operating at frequencies >200 kHz.

No No No No No Yes No

AOC = Area of Concern; AOI = Area of Interest; BOEM = Bureau of Ocean Energy Management; BSEE = Bureau of Safety and Environmental 

Enforcement; CFR = Code of Federal Regulations; CPA = Central Planning Area; EPA = Eastern Planning Area; ft = foot; G&G = geological and 

geophysical; HRG = high-resolution geophysical; kHz = kilohertz; km = kilometer; m = meter; mi = mile; NMFS = National Marine Fisheries 

Service; NMS = National Marine Sanctuary; NTL = Notice to Lessees and Operators; OCS = Outer Continental Shelf; PAM = passive acoustic 

monitoring; PSO = protected species observer; WAZ = wide azimuth (survey).
Gulf of Mexico G&G Activities Programmatic EIS Tables-13

Table 2.7-1. Alternative E1: 10-Percent Reduction of Deep-Penetration Seismic, Multi-Client Surveys (in line miles) from the Maximum Projected 

Activity Levels of Geological and Geophysical Activities for Oil and Gas Exploration in the Area of Interest

Year Western Planning Area Central Planning Area Eastern Planning Area

HRG VSP SWD 2D 3D1 WAZ2 4D HRG VSP SWD 2D 3D1 WAZ2 4D HRG VSP 2D 3D1 WAZ2 4D

1 

Shallow (3)

400

(3)

93 0 0 (1)2,620 0 (1)9,507

(22)

2,000

(17)

496 0 0 (2)13,605 0 (1)9,900

(2)

100

(1)

31 0 0 0 0 

Deep (4)

1,100

(19)

558 3 (0.33)3,600

(1)

8,625

(1)

6,728

(3)

29,700

(32)

5,600

(35)

1,054 9 (0.67)7,200

(5)

40,686

(6)

52,999

(6)

59,400 0 (2)62

(1)

180

(1)

1,918 0 0 

2 

Shallow (3)

350

(2)

62 0 0 0 0 0 (22)2,000

(15)

434 0 0 (2)18,400

(1)

4,897 0 (2)100 0 0 0 0 0 

Deep (5)

1,200

(14)

403 1 (0.5)1,620

(1)

13,731

(3)

20,043

(3)

29,700

(32)

5,600

(33)

992 8 (0.50)1,620

(5)

42,618

(5)

46,347

(6)

59,400

(1)

50

(1)

400

(1)

360

(1)

4,139 0 0 

3 

Shallow (3)

350

(3)

93 0 0 0 0 (1)9,507

(20)

1,950

(14)

403 0 0 (2)16,538 0 (1)9,900

(1)

50

(1)

31 0 0 0 0 

Deep (6)

1,300

(16)

465 2 (1)540

(1)

8,625

(2)

17,049

(3)

29,700

(35)

5,850

(30)

917 10 (1)1,620

(4)

33,955

(5)

44,203

(6)

59,400

(2)

100

(2)

62

(1)

18,810

(1)

4,139 0 0 

4 

Shallow (3)

325

(2)

62 0 0 (1)2,620 0 0 (18)1,900

(15)

434 0 0 (2)21,433

(1)

6,781 0 0 0 0 0 0 

Deep (6)

1,300

(14)

403

2 (1.00)

540

(1)

3,786

(3)

20,550

(3)

29,700

(35)

5,850

(33)

992

11 (1)

1,620

(2)

18,658

(2)

21,471

(6)

59,400

(2)

100

(1)

5

(1)

24,210

(1)

10,080

(1)

11,210 0 

5 

Shallow (3)

300

(3)

93 0 0 0 0 0 (18)1,900

(12)

372 0 0 (2)13,715 0 (1)9,900 0 0 0 0 0 

Deep (6)

1,400

(16)

465 2 (1.00)540

(1)

4,927

(1)

7,287

(3)

29,700

(40)

6,200

(27)

806 7 (1)1,620

(3)

26,605

(5)

40,507

(6)

59,400

(1)

50

(1)

5

(1)

9,360

(1)

15,120 0 0 

6 

Shallow (3)

300

(1)

31 0 0 0 0 0 (17)1,700

(10)

310 0 0 (2)17,661

(1)

3,453 0 0 0 0 0 0 0 

Deep (6)

1,400

(8)

248 1 0 (1)8,625

(1)

9,205

(3)

29,700

(42)

6,500

(24)

713 8 0 (2)12,805

(3)

25,872

(6)

59,400

(2)

100

(1)

1 0 (1)15,120 0 0 

7 

Shallow (3)

600

(1)

31 0 0 (1)2,620 0 (2)19,013

(15)

1,500

(14)

403 0 0 (1)12,578

(1)

0

(1)

9,900 0 0 0 0 0 0 

Deep (7)

1,475

(5)

155 0 (0.33)1,800

(1)

9,010

(1)

8,690

(3)

29,700

(45)

7,000

(30)

899 9 (0.67)3,600

(2)

13,796

(4)

34,208

(6)

59,400

(3)

150

(1)

0

(1)

810

(1)

10,080

(1)

2,651 0 

8 

Shallow (4)

800

(1)

31 0 0 0 0 0 (15)1,500

(13)

403 0 0 (2)20,252

(1)

4,514 0 0 0 0 0 0 0 

Deep (7)

1,475

(5)

155 0 0 (1)14,162

(1)

8,690

(3)

29,700

(50)

7,500

(29)

868 7 0 (2)

16,253

(3)

30,088

(6)

59,400

(4)

200

(1)

5 

(1)

19,350

(1)

10,080

(1)

4,345 0 

9 Shallow (4)

800

(1)

31 0 0 0 0 (2)19,013

(15)

1,500

(10)

310 0 0 (1)12,286 0 (1)9,900 0 0 0 0 0 0 
Table 2.7-1. Alternative E1: 10-Percent Reduction of Deep-Penetration Seismic, Multi-Client Surveys (in line miles) from the Maximum Projected 

Activity Levels of Geological and Geophysical Activities for Oil and Gas Exploration in the Area of Interest (continued)

Tables-14 Tables

Year Western Planning Area Central Planning Area Eastern Planning Area

HRG VSP SWD 2D 3D1 WAZ2 4D HRG VSP SWD 2D 3D1 WAZ2 4D HRG VSP 2D 3D1 WAZ2 4D

Deep (8)

1,500

(8)

248 1 (1)540

(1)

13,368

(1)

8,690

(3)

29,700

(50)

7,500

(24)

713 8 (1)1,620

(1)

7,819

(3)

31,056

(6)

59,400

(4)

200

(1)

0

(1)

24,660

(1)

10,080

(1)

4,476 0 

10

Shallow (6)

1,000

(1)

31 0 0 0 2,620 0 0 (12)1,200

(10)

310 0 0 (2)20,126

(1)

3,066 0 0 0 0 0 0 0 

Deep (8)

1,500

(5)

155 1 0 (1)8,516 0 (3)29,700

(55)

8,000

(24)

713 10 0 (1)10,002

(3)

26,210

(6)

59,400

(4)

200

(1)

5

(1)

9,000

(1)

10,080 0 0 

Totals (98)

18,875

(128)

3,813 13 (5.16)9,180

(14)

103,853

(14)

106,934

(36)

354,040

(590)

82,750

(419)

12,542 87 (5.84)18,900

(45)

389,789

(44)

375,674

(65)

643,500

(28)

1,400

(14)

607

(9)

106,740

(10)

90,836

(4)

22,682 0 

2D = two-dimensional; 3D = three-dimensional; 4D = four-dimensional; ft = foot; HRG = high-resolution geophysical; m= meter; SWD = seismic while drilling; VSP = vertical seismic profile; 

WAZ = wide azimuth (survey).

Shallow = <200-m (656-ft) water depth; Deep = >200-m (656-ft) water depth.

Numbers in parentheses represent the number of surveys; numbers without parentheses represent the distance in miles. 1 3D surveys include ocean bottom cable surveys, nodal surveys, and vertical cable surveys. 2 WAZ estimates include coil shooting (exclusive to WesternGeco).
Gulf of Mexico G&G Activities Programmatic EIS Tables-15

Table 2.7-2. Alternative E2: 25-Percent Reduction of Deep-Penetration Seismic, Multi-Client Surveys (in line miles) from the Maximum Projected 

Activity Levels of Geological and Geophysical Activities for Oil and Gas Exploration in the Area of Interest

Year Water 

Depth

Western Planning Area Central Planning Area Eastern Planning Area

HRG VSP SWD 2D 3D1 WAZ2 4D HRG VSP SWD 2D 3D1 WAZ2 4D HRG VSP 2D 3D1 WAZ2 4D

1 

Shallow (3)

400

(3)

93 0 0 (1)2,183 0 (1)7,922

(22)

2,000

(17)

496 0 0 (2)11,338 0 (1)8,250

(2)

100

(1)

31 0 0 0 0 

Deep (4)

1,100

(19)

558 3 (0.33)3,000

(1)

7,187

(1)

5,607

(3)

24,750

(32)

5,600

(35)

1,054 9 (0.67)6,000

(5)

33,905

(6)

44,166

(6)

49,500 0 (2)62

(1)

150

(1)

1,598 0 0 

2 

Shallow (3)

350

(2)

62 0 0 0 0 0 (22)2,000

(15)

434 0 0 (2)15,333

(1)

4,081 0 (2)100 0 0 0 0 0 

Deep (5)

1,200

(14)

403 1 (0.5)1,350

(1)

11,443

(3)

16,703

(3)

24,750

(32)

5,600

(33)

992 8 (0.50)1,350

(5)

35,515

(5)

38,623

(6)

49,500

(1)

50

(1)

400

(1)

300

(1)

3,449 0 0 

3 

Shallow (3)

350

(3)

93 0 0 0 0 (1)7,922

(20)

1,950

(14)

403 0 0 (2)13,781 0- (1)8,250

(1)

50

(1)

31 0 0 0 0 

Deep (6)

1,300

(16)

465 2 (1.00)450

(1)

7,187

(2)

14,207

(3)

24,750

(35)

5,850

(30)

917 10 (1)1,350

(4)

28,296

(5)

36,836

(6)

49,500

(2)

100

(2)

62

(1)

15,675

(1)

3,449 0 0 

4 

Shallow (3)

325

(2)

62 0 0 (1)2,183 0 0 (18)1,900

(15)

434 0 0 (2)17,861

(1)

5,651 0 0 0 0 0 0 0 

Deep (6)

1,300

(14)

403

2 (1.00)

450

(1)

3,155

(3)

17,125

(3)

24,750

(35)

5,850

(33)

992

11 (1)

1,350

(2)

15,548

(2)

17,893

(6)

49,500

(2)

100

(1)

5

(1)

20,175

(1)

8,400

(1)

9,342 0 

5 

Shallow (3)

300

(3)

93 0 0 0 0 0 (18)1,900

(12)

372 0 0 (2)11,429 0 (1)8,250 0 0 0 0 0 0 

Deep (6)

1,400

(16)

465 2 (1.00)450

(1)

4,106

(1)

6,073

(3)

24,750

(40)

6,200

(27)

806 7 (1)1,350

(3)

22,171

(5)

33,756

(6)

49,500

(1)

50

(1)

5

(1)

7,800

(1)

12,600 0 

6 

Shallow (3)

300

(1)

31 0 0 0 0 0 (17)1,700

(10)

310 0 0 (2)14,717

(1)

2,878 0 0 0 0 0 0 0 

Deep (6)

1,400

(8)

248 1 0 (1)7,187

(1)

7,671

(3)

24,750

(42)

6,500

(24)

713 8 0 (2)10,671

(3)

21,560

(6)

49,500

(2)

100

(1)

1 0 (1)12,600 0 0 

7 

Shallow (3)

600

(1)

31 0 0 (1)2,183 0 (2)15,845

(15)

1,500

(14)

403 0 0 (1)10,481

(1)

-

(1)

8,250 0 0 0 0 0 0 

Deep (7)

1,475

(5)

155 0 (0.33)1,500

(1)

7,508

(1)

7,242

(3)

24,750

(45)

7,000

(30)

899 9 (0.67)3,000

(2)

11,497

(4)

28,507

(6)

49,500

(3)

150

(1)

0

(1)

675

(1)

8,400

(1)

2,209 0 

8 

Shallow (4)

800

(1)

31 0 0 0 0 0 (15)1,500

(13)

403 0 0 (2)16,877

(1)

3,762 0 0 0 0 0 0 0 

Deep (3)

400

(3)

93 0 0 (1)2,183 0 (1)

7,922

(22)

2,000

(17)

496 0 0 (2)11,338 0 (1)8,250

(2)

100

(1)

31 0 0 0 0 

9 Shallow (4)

800

(1)

31 0 0 0 0 (2)15,845

(15)

1,500

(10)

310 0 0 (1)10,238 0 (1)8,250 0 0 0 0 0 0 
Table 2.7-2. Alternative E2: 25-Percent Reduction of Deep-Penetration Seismic, Multi-Client Surveys (in line miles) from the Maximum Projected 

Activity Levels of Geological and Geophysical Activities for Oil and Gas Exploration in the Area of Interest (continued)

Tables-16 Tables

Year Water 

Depth

Western Planning Area Central Planning Area Eastern Planning Area

HRG VSP SWD 2D 3D1 WAZ2 4D HRG VSP SWD 2D 3D1 WAZ2 4D HRG VSP 2D 3D1 WAZ2 4D

Deep (8)

1,500

(8)

248 1 (1)450

(1)

11,140

(1)

7,242

(3)

24,750

(50)

7,500

(24)

713 8 (1)1,350

(1)

6,516

(3)

25,880

(6)

49,500

(4)

200

(1)

0

(1)

20,550

(1)

8,400

(1)

3,730 0 

10

Shallow (6)

1,000

(1)

31 0 0 (1)2,183 0 0 (12)1,200

(10)

310 0 0 (2)16,772

(1)

2,555 0 0 0 0 0 0 0 

Deep (8)

1,500

(5)

155 1 0 (1)7,097 0 (3)24,750

(55)

8,000

(24)

713 10 0 (1)8,335

(3)

21,842

(6)

49,500

(4)

200

(1)

5

(1)

7,500

(1)

8,400 0 0 

Totals (98)

18,875

(128)

3,813 13 (5.16)7,650

(14.00)

86,544

(14)

89,111

(36)

295,034

(590)

82,750

(419)

12,542 87 (5.84)15,750

(14)

324,824

(44)

313,061

(65)

536,250

(28)

1,400

(14)

607

(9)

88,950

(10)

75,697

(4)

18,902 0 

2D = two-dimensional; 3D = three-dimensional; 4D = four-dimensional (3D time-lapse); ft = foot; HRG = high-resolution geophysical; m = meter; SP = seismic profiling; SWD = seismic 

while drilling; VSP = vertical seismic profile; WAZ = wide azimuth (survey).

Shallow = <200-m (656-ft) water depth; Deep = >200-m (656-ft) water depth.

Numbers in parentheses represent the number of surveys; numbers without parentheses represent the distance surveyed in miles.

1 3D surveys include ocean bottom cable surveys, nodal surveys, and vertical cable surveys. 2 WAZ estimates include coil shooting (exclusive to WesternGeco).
Gulf of Mexico G&G Activities Programmatic EIS Tables-17

Table 2.9-1. Alternative G, the No New Activity Alternative: Projected Activity Levels of Geological and 

Geophysical Activities in the Area of Interest Over the 10-Year Period

Activity Units Oil & Gas Renewable Minerals Totals

Geophysical

Non-Airgun HRG Surveys # of Surveys 0 Line Miles

VSP Surveys # of Surveys 449

0 0 

449

Line Miles 2,544 2,544

SWD Surveys # of Surveys 100 100

Line Miles 0 0

2D Surveys # of Surveys 0 Line Miles

3D Surveys # of Surveys 0 Line Miles

WAZ Surveys # of Surveys 0 Line Miles

4D Surveys # of Surveys 0 Line Miles

Total 3D, WAZ, 4D Survey # of Surveys 0 Line Miles

CSEM # of Surveys 0 0 0 0

Line Miles 0 0 0 0

Geological

Bottom Sampling

CPT Number 0 0 0 0

Corings Number 0 0 0 0

Grab Sample Number 0 0 0 0

Vibracores Number 0 0 0 0

Jet Probe Number 0 0 0 0

Bottom Sampling Subtotal Number 0 0 0 0

Bottom Impacts (10 m2/sample) m2 0 0 0 0

Shallow Drill Test Wells Number 0 0 0 0

COST Wells Number 0 0 0 0

Bottom Impacts (20,000 m2/well) m2 0 0 0 0

Other

Bottom-Founded Monitoring Buoy Number 0 0 0 0

Bottom Impacts 

(Footprint 0.56 m2/buoy + 

Sweep 34,000 m2/buoy)

m2 0 0 0 0 

2D = two-dimensional; 3D = three-dimensional; 4D = four-dimensional; COST = Continental Offshore 

Stratigraphic Test; CPT = cone penetrometer test; CSEM = controlled source electromagnetic; 

HRG = high-resolution geophysical; m2

 = square meters; SWD = seismic while drilling; VSP = vertical 

seismic profile; WAZ = wide azimuth (survey).
Tables-18 Tables

Table 2.13-1. Impact Levels by Resource and Applicable Impact-Producing Factors Across Alternatives A through G, as Discussed in 

Chapter 2.13

Resource and Impact-Producing Factor Alternative1

A B C D E F G*

Marine Mammals

Active Acoustic 

Sound Sources

Deep-Penetration Airguns Mod Mod2,3,4,5 Mod2,4,5 Mod2,5,7 Mod2,4,5 Min2,3,4,5 No Impact

Shallow-Penetration Airguns Min Min2,3,4,5 Min2,4,5 Min2,5,7 Min2,4,5 Min2,3,4,5 No Impact

HRG Equipment Min Min Min6 Min6 Min6 Min6 No Impact

Vessel and Equipment Noise Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Vessel Traffic Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod No Impact

Aircraft Traffic and Noise Nom Nom Nom Nom Nom Nom No Impact

Trash and Debris Nom Nom Nom Nom Nom Nom No Impact

Entanglement Nom Nom Nom Nom Nom Nom No Impact

Accidental Fuel Spills Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Cumulative (incremental increase) Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min

Sea Turtles

Active Acoustic 

Sound Sources

Airguns Min Min Min Min Min Min No Impact

HRG Equipment Nom-Min Nom-Min Nom-Min6 Nom-Min6 Nom-Min6 Nom-Min6 No Impact

Vessel and Equipment Noise Nom Nom Nom Nom Nom Nom No Impact

Vessel Traffic Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod No Impact

Aircraft Traffic and Noise Nom Nom Nom Nom Nom Nom No Impact

Trash and Debris Nom Nom Nom Nom Nom Nom No Impact

Entanglement Nom Nom Nom Nom Nom Nom No Impact

Accidental Fuel Spills Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Cumulative (incremental increase) Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min

Fisheries Resources and Essential Fish Habitat

Active Acoustic 

Sound Sources

Airguns Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

HRG Equipment Nom Nom Nom Nom Nom Nom No Impact

Vessel and Equipment Noise Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Trash and Debris Nom Nom Nom Nom Nom Nom No Impact

Seafloor Disturbance Nom Nom Nom Nom Nom Nom No Impact

Drilling Discharges Nom Nom Nom Nom Nom Nom No Impact

Entanglement Nom Nom Nom Nom Nom Nom No Impact

Accidental Fuel Spills Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Cumulative (incremental increase) Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min
Table 2.13-1. Impact Levels by Resource and Applicable Impact-Producing Factor Across Alternatives A through G, as Discussed in 

Chapter 2.13 (continued)

Gulf of Mexico G&G Activities Programmatic EIS Tables-19

Resource and Impact-Producing Factor Alternative1

A B C D E F G

Benthic Communities

Active Acoustic 

Sound Sources

Airguns Nom Nom Nom Nom Nom Nom No Impact

HRG Equipment Nom Nom Nom Nom Nom Nom No Impact

Trash and Debris Nom Nom Nom Nom Nom Nom No Impact

Seafloor Disturbance Nom Nom Nom Nom Nom Nom No Impact

Drilling Discharges Nom Nom Nom Nom Nom Nom No Impact

Accidental Fuel Spills Nom Nom Nom Nom Nom Nom No Impact

Cumulative (incremental increase) Nom Nom Nom Nom Nom Nom No-Nom

Marine and Coastal Birds

Active Acoustic 

Sound Sources

Airguns Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

HRG Equipment Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Vessel and Equipment Noise Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Vessel Traffic Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Aircraft Traffic and Noise Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Trash and Debris Nom Nom Nom Nom Nom Nom No Impact

Accidental Fuel Spills Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod No Impact

Cumulative (incremental increase) Nom Nom Nom Nom Nom Nom Nom

Marine Protected Areas

Active Acoustic 

Sound Sources

Airguns Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod No Impact

HRG Equipment Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Trash and Debris Nom Nom Nom Nom Nom Nom No Impact

Seafloor Disturbance Nom Nom Nom Nom Nom Nom No Impact

Drilling Discharges No-Nom No-Nom No-Nom No-Nom No-Nom No-Nom No Impact

Accidental Fuel Spills Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod Nom-Mod No Impact

Cumulative (incremental increase) Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No-Nom

Sargassum Communities

Vessel Traffic Nom Nom Nom Nom Nom Nom No Impact

Vessel Discharges Nom Nom Nom Nom Nom Nom No Impact

Trash and Debris Nom Nom Nom Nom Nom Nom No Impact

Accidental Fuel Spills Nom Nom Nom Nom Nom Nom No Impact

Cumulative (incremental increase) Nom Nom Nom Nom Nom Nom No-Nom
Table 2.13-1. Impact Levels by Resource and Applicable Impact-Producing Factor Across Alternatives A through G, as Discussed in 

Chapter 2.13 (continued)

Tables-20 Tables

Resource and Impact-Producing Factor Alternative1

A B C D E F G

Commercial Fisheries

Active Acoustic 

Sound Sources

Airguns Min Min Min Min Min Min No Impact

HRG Equipment Nom Nom Nom Nom Nom Nom No Impact

Vessel Traffic Nom Nom Nom Nom Nom Nom No Impact

Stand-Off Distance Min Min Min Min Nom-Min Min No Impact

Seafloor Disturbance Min Min Min Min Min Min No Impact

Entanglement Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min No Impact

Accidental Fuel Spills Nom Nom Nom Nom Nom Nom No Impact

Cumulative (incremental increase) Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom-Min Nom

Recreational Fisheries

Active Acoustic 

Sound Sources

Airguns Nom Nom Nom Nom Nom Nom No Impact

HRG Equipment Nom Nom Nom Nom Nom Nom No Impact

Vessel Traffic Nom Nom Nom Nom Nom Nom No Impact

Stand-Off Distance Nom Nom Nom Nom Nom Nom No Impact

Accidental Fuel Spills Nom Nom Nom Nom Nom Nom No Impact

Cumulative (incremental increase) Nom Nom Nom Nom Nom Nom Nom

Archaeological Resources

Seafloor Disturbance Nom-Maj Nom-Maj Nom-Maj Nom-Maj Nom-Maj Nom-Maj No Impact

Drilling Discharges Nom Nom Nom Nom Nom Nom No Impact

Entanglement Nom-Maj Nom-Maj Nom-Maj Nom-Maj Nom-Maj Nom-Maj No Impact

Accidental Fuel Spills Nom Nom Nom Nom Nom Nom No Impact

Cumulative (incremental increase) Nom Nom Nom Nom Nom Nom No-Nom

Multiple-Use Areas

Vessel Traffic No-Nom No-Nom No-Nom No-Nom No-Nom No-Nom No-Nom

Aircraft Traffic and Noise No-Nom No-Nom No-Nom No-Nom No-Nom No-Nom No-Nom

Stand-Off Distance No-Nom No-Nom No-Nom No-Nom No-Nom No-Nom No-Nom

Seafloor Disturbance No-Nom No-Nom No-Nom No-Nom No-Nom No-Nom No-Nom

Accidental Fuel Spills Nom Nom Nom Nom Nom Nom Nom

Cumulative (incremental increase) Nom Nom Nom Nom Nom Nom Nom
Table 2.13-1. Impact Levels by Resource and Applicable Impact-Producing Factor Across Alternatives A Through G, as Discussed in 

Chapter 2.13 (continued)

Gulf of Mexico G&G Activities Programmatic EIS Tables-21

Resource and Impact-Producing Factor Alternative1

A B C D E F G

Human Resources, Land Use, and Economics

Land Use and Infrastructure Ben-Min Ben-Min Ben-Min Ben-Min Ben-Min Ben-Min Min-Mod

Environmental Justice Ben-Nom Ben-Nom Ben-Nom Ben-Nom Ben-Nom Ben-Nom Min

Demographics Ben-Nom Ben-Min Ben-Min Ben-Min Minor Minor Min-Mod

Economics Ben-Min Ben-Mod Ben-Min Ben-Mod Min-Mod Min-Mod Mod-Maj

Note: Impacts are categorized as Beneficial, Major, Moderate, Minor, or Nominal (refer to Chapter 4.1.2 for definitions).

Ben = Beneficial Impact; G&G = geological and geophysical; HRG = high-resolution geophysical; Maj = Major Impact; Min = Minor Impact; Mod = Moderate

Impact; No = No Impact; Nom = Nominal Impact. 1 Alternative A = Pre-Settlement (June 2013) Alternative; Alternative B = Settlement Agreement Alternative; Alternative C = Alternative A Plus Additional 

Mitigation Measures; Alternative D = Alternative C Plus Marine Mammal Shutdowns; Alternative E = Alternative C at Reduced Activity Levels; 

Alternative F = Alternative C Plus Area Closures; Alternative G = No New Activity Alternative. 2 Provides protection to coastal marine mammal species (i.e., common bottlenose dolphins, manatees, Atlantic spotted dolphins) when they are reproducing 

(calving) and increases the fitness values of the reproducing species. 3 Provides protection for whale species (Bryde’s, beaked, sperm, dwarf and pygmy sperm whales) and manatees providing localized reduction in sound exposure 

and associated impacts for those species. 4 Provides protection to bay, sound and estuary (BSE) stocks of common bottlenose dolphins, individual coastal stocks of common bottlenose dolphins and 

Atlantic spotted dolphins, and manatees; individual beaked whales and sperm whales, as well as potentially calving sperm whales; the small population of 

geographically and genetically distinct Bryde’s whales in the GOM. 5 Provides protection to vocalizing marine mammals. 6 Provides protection to all marine mammals and sea turtles, with additional protection (shutdown) for sperm, Bryde’s, beaked, dwarf and pygmy sperm whales, 

and manatees. 7 Provides protection for all marine mammals except bow-riding or actively approaching dolphins (i.e., common bottlenose, Fraser’s, Clymene’s, rough-toothed, 

striped, spinner, Atlantic spotted, pantropical, and Risso’s).

* Impact determinations provided for Alternative G assume no new permitted activity and, therefore, no routine or accidental events. The G&G activity from 

previously permitted activities are included in the cumulative analysis. 
Tables-22 Tables

Table 2.13-2. Impact Levels for Marine Mammals from Airguns and Those Species Groups Protects Across Alternatives A through G, as 

Discussed in Chapter 4.2

Resource and 

Impact-Producing Factor

Alternative 

A B C D E F G* 

Marine Mammals

Active 

Acoustic 

Sound 

Sources

Airguns Mod Mod Mod Mod Mod Min Min

Additional protection 

afforded to marine 

mammal species groups 

from mitigation measures
Table 2.13-2. Impact Levels for Marine Mammals from Airguns and Those Species Groups Protects Across Alternatives A through G, as 

Discussed in Chapter 4.2 (continued)

Gulf of Mexico G&G Activities Programmatic EIS Tables-23

Coastal marine mammal species (i.e., common bottlenose dolphins, manatees, Atlantic spotted dolphins) when they are reproducing 

(calving) or bay, sound, and estuary stocks of common bottlenose dolphins, individual coastal stocks of common bottlenose dolphins 

and Atlantic spotted dolphins as applicable.

Manatees and their offspring.

Vocalizing marine mammals.

Sperm, dwarf, and pygmy sperm whales.

All marine mammals.

Bryde’s whale and/or the genetically distinct Bryde’s whales in the GOM as applicable.

Calving sperm whales.

Except bow-riding dolphins (common bottlenose, Fraser’s, Clymene’s, rough-toothed, striped, spinner, Atlantic spotted, pantropical, and 

Risso’s).

Beaked whales.

Note: Impacts are categorized as Moderate, Minor, or Nominal (refer to Chapter 4.1.2 for definitions).

* Impact determinations provided for Alternative G are prior to any decline in geological and geophysical activities, and these ratings will decline over time as 

activities are phased out.
Tables-24 Tables

Table 3.1-1. Types of Geological and Geophysical Activities Included in this Programmatic Environmental Impact Statement

Survey Type

Applicable Program 

Areas Purpose(s)

O&G REN MMP

Deep-Penetration Seismic Surveys

Most, if not all deep-penetration seismic surveys require the use 

of airguns. Seismic surveys evaluate subsurface geological 

formations to assess potential hydrocarbon reservoirs and 

optimally site exploration and development wells. The 2D 

surveys provide a cross-sectional image of the Earth’s structure 

while 3D provide a volumetric image of underlying geological 

structures. Repeated 3D surveys result in time lapse, or 4D, 

surveys that assess the depletion of a reservoir. The VSP 

surveys provide information about geologic structure, lithology, 

and fluids.

2D Seismic Surveys X -- --

3D Seismic Surveys X -- --

Ocean-Bottom 2D Seismic Surveys (Cable or 

Nodes) X -- --

Ocean-Bottom 3D Seismic Surveys (Cable or 

Nodes) X -- --

Wide-Azimuth and Related Multi-Vessel Surveys X -- --

Borehole Seismic Surveys (2D and 3D VSP 

Surveys) X -- --

Vertical Cable Surveys X -- --

4D Time-Lapse Surveys X -- --

Airgun High-Resolution Geophysical Surveys A single airgun used to assess shallow hazards, benthic habitats, 

High-Resolution Seismic Surveys X X - renewable energy structure emplacement. 

Non-Airgun Acoustic High-Resolution Geophysical Surveys Assess shallow hazards, potential sand and gravel resources for 

coastal restoration, archaeological resources, and benthic 

habitats. Devices used in subbottom profiling surveys include

• sparkers;

• boomers;

• pingers; and

• CHIRP subbottom profilers.

Subbottom Profiling Surveys X X X 

Side-Scan Sonars X X X 

Single-Beam and Multibeam Echosounders X X X 

Non-Acoustic Marine Geophysical Surveys

Electromagnetic signals are used to develop a conductivity/

resistivity profile of the seafloor, helping to identify economic 

hydrocarbon accumulations and aid with archaeological surveys.

Marine Gravity Surveys X -- --

Marine Magnetic Surveys X -- --

Marine Magnetotelluric Surveys X -- --

Marine Controlled Source Electromagnetic Surveys X -- --

Airborne Remote Surveys Gravity and magnetic surveys are used to assess structure and 

sedimentary properties of subsurface horizons. Airborne 

magnetic surveys evaluate deep crustal structure, salt-related 

structure, and intra-sedimentary anomalies.

Airborne Gravity Surveys X -- --

Airborne Magnetic Surveys X -- --
Table 3.1-1. Types of Geological and Geophysical Activities Included in this Programmatic Environmental Impact Statement (continued)

Gulf of Mexico G&G Activities Programmatic EIS Tables-25

Survey Type

Applicable Program 

Areas Purpose(s)

O&G REN MMP

Geological and Geotechnical Surveys Collect surface and near surface sediment samples to assess 

seafloor properties for siting structures such as platforms, 

pipelines, or cables. Different types of geologic cores include

• gravity corers;

• multicorers;

• piston corers;

• rotary corers;

• ROV push cores; and

• vibracorers. 

Geologic coring is also used to assess sediment characteristics 

for use in coastal restoration projects. Shallow test drilling is 

conducted to place test equipment into a borehole to evaluate 

gas hydrates or other properties. The COST wells evaluate 

stratigraphy and hydrocarbon potential without drilling directly 

into oil and gas bearing strata.

Grab and Box Sampling X X X 

Geologic Coring X X X 

Shallow Test Drilling X X --

COST Wells X X --

Cone Penetrometer Tests X X --

Other Surveys and Equipment The devices in this category assist in the execution of surveys, 

either by providing location or facilitating underwater service 

tasks. Additionally, water guns are no longer used as a seismic 

source except in extremely rare instances.

Acoustic Pingers X X --

Transponders, Transceivers, Responders X X --

ROVs and AUVs X X --

2D = two-dimensional; 3D = three-dimensional; 4D = four-dimensional; AUV = autonomous underwater vehicle; CHIRP = compressed 

high-intensity radar pulse; COST = continental offshore stratigraphic test; HRG = high-resolution geophysical; MMP = Marine Minerals Program; 

O&G = Oil and Gas Program; REN = Renewable Energy Program; ROV = remotely operated vehicle; VSP = vertical seismic profile.
Tables-26 Tables

Table 3.2-1. Projected Range of Activity Levels of Acoustic Geophysical Activities for Oil and Gas 

Exploration in the Area of Interest Over the 10-Year Time Period (numbers of surveys) and 

Survey Line Distance (miles)

Year Water 

Depth

Western Planning Area

HRG VSP SWD 2D 3Da WAZb 4D

Year 

1 

Shallow (1-3)

125-400

(1-3)

31-93 (0) (0) (0-1)0-2,911 (0) (0-1)0-10,563

Deep (2-4)

550-1,100

(12-19)

372-558 (0-3) (0-1)0-4,000

(0-1)

0-9,583

(0-1)

0-7,476

(1-3)

11,000-33,000

Year

2 

Shallow (1-3)

110-350

(0-2)

0-62 (0) (0) (0) (0) (0)

Deep (3-5)

720-1,200

(7-14)

202-403 (0-1) (0-1)0-1,800

(0-1)

0-15,257

(1-3)

7,420-22,270

(1-3)

11,000-33,000

Year

3 

Shallow (0-3)

0-350

(1-3)

31-93 (0) (0) (0) (0) (0-1)

0-10,563

Deep (3-6)

650-1,300

(10-16)

290-465 (0-2) (0-1)0-600

(0-1)

0-9,583

(0-2)

0-18,943

(1-3)

11,000-33,000

Year

4 

Shallow (1-3)

110-325

(0-2)

0-62 (0) (0) (0-1)0-2,911 (0) (0)

Deep (2-6)

957-1,300

(10-14)

287-403 (0-2) (0-1)0-600

(0-1)

0-4,207

(1-3)

7,610-22,833

(1-3)

11,000-33,000

Year

5 

Shallow (1-3)

100-300

(1-3)

31-93 0 (0) (0) (0) (0)

Deep (4-6)

933-1,400

(11-16)

320-465 (0-2) (0-1)0-600

(0-1)

0-5,474

(0-1)

0-8,097

(1-3)

11,000-33,000

Year

6 

Shallow (1-3)

100-300

(0-1)

0-31 0 (0) (0) (0) (0)

Deep (4-6)

933-1,400

(6-8)

186-248 (0-1) (0) (0-1)0-9,583

(0-1)

0-10,228

(1-3)

11,000-33,000

Year

7 

Shallow (1-3)

200-600

(0-1)

0-31 0 (0) (0-1)0-2,911 (0) (0-2)0-21,126

Deep (5-7)

1,200-1,475

(3-5)

93-155 0 (0-1)0-2,000

(0-1)

0-10,011

(0-1)

0-9,656

(1-3)

11,000-33,000

Year

8 

Shallow (2-4)

400-800

(0-1)

0-31 0 (0) (0) (0) (0)

Deep (5-7)

1,200-1,475

(3-5)

93-155 0 (0) (0-1)0-15,735

(0-1)

0-9,656

(1-3)

11,000-33,000

Year

9 

Shallow (2-4)

400-800

(0-1)

0-31 0 (0) (0) (0) (0-2)

0-21,126

Deep (6-8)

1,300-1,500

(6-8)

186-248 (0-1) (0-1)0-600

(0-1)

0-14,853

(0-1)

0-9,656

(1-3)

11,000-33,000

Year

10

Shallow (5-6)

900-1,000

(0-1)

0-31 0 (0) (0-1)0-2,911 (0) (0)

Deep (6-8)

1,300-1,500

(4-5)

124-155 (0-1) (0) (0-1)0-9,462 (0) (1-3)11,000-33,000

Totals (55-98)

12,188-18,875

(75-128)

2,246-3,843 (0-13) (0-7) 0-10,200

(0-14) 

0-115,392

(2-14) 

15,030-118,815

(10-36) 

110,000-393,378
Gulf of Mexico G&G Activities Programmatic EIS Tables-27

Table 3.2-1. Projected Range of Activity Levels of Acoustic Geophysical Activities for Oil and Gas 

Exploration in the Area of Interest Over the 10-Year Time Period (numbers of surveys) and 

Survey Line Distance (miles) (continued)

Year Water 

Depth

Central Planning Area

HRG VSP SWD 2D 3Da WAZb 4D

Year

1 

Shallow (15-22)

1,360-2,000

(11-17)

341-496 0 (0) (0-2)0-15,117 (0) (0-1)0-11,000

Deep (21-32)

3,670-5,600

(22-35)

696-1,054 (6-9) (0-1) 0-8,000

(3-5)

29,836-45,207

(4-6)

38,866-58,888

(4-6)

43,560-66,000

Year

2 

Shallow (15-22)

1,360-2,000

(9-15)

286-434 0 (0) (0-2)0-20,444

(0-1)

0-5,441 (0)

Deep (21-32)

3,670-5,600

(21-33)

655-992 (5-8) (0-1) 0-1800

(3-5)

31,253-47,353

(3-5)

33,988-51,497

(4-6)

43,560-66,000

Year

3 

Shallow (13-20)

1,267-1,950

(9-14)

266-403 0 (0) (0-2)

0-18375 (0) (0-1)

0-11,000

Deep (23-35)

3,840-5,850

(19-30)

605-917 (6-10) (0-1)0-1,800

(2-4)

24,900-37,728

(3-5)

32,415-49,114

(4-6)

43,560-66,000

Year

4 

Shallow (14-18)

1,480-1,900

(11-15)

325-434 0 (0) (0-2)0-23814

(0-1)

0-7,534 (0)

Deep (31-35)

5,260-5,850

(24-33)

744-992 (7-11) (0-1)0-1,800

(0-2)

0-20,731

(1-2)

17,892-23,857

(5-6)

49,600-66,000

Year

5 

Shallow (14-18)

1,480-1,900

(10-12)

335-372 0 (0) (0-2)

0-15,239 (0) (0-1)

0-11,000

Deep (36-40)

5,580-6,200

(23-27)

725-806 (5-7) (0-1)0-1,800

(1-3)

26,605-29,561

(4-5)

40,507-45,008

(5-6)

65,340-66,000

Year

6 

Shallow (15-17)

1,530-1,700

(9-10)

279-310 0 (0) (0-2)

0-19,623

(0-1)

0-3,837 (0)

Deep (38-42)

5,850-6,500

(21-24)

642-713 (6-8) (0) (0-2)0-14,228

(2-3)

25,872-28,747

(5-6)

65,340-66,000

Year

7 

Shallow (13-15)

1,350-1,500

(11-14)

363-403 0 (0) (0-1)0-13,975 (0) (0-1)0-11,000

Deep (40-45)

6,300-7,000

(26-30)

809-899 (7-9) (0-1) 0-4,000

(0-2)

0-15,329

(3-4)

34,208-38,009

(5-6)

65,340-66,000

Year

8 

Shallow (13-15)

1,350-1,500

(11-13)

363-403 0 (0) (0-2)0-22,502

(0-1)

0-5016 (0)

Deep (45-50)

6,750-7,500

(25-29)

781-868 (5-7) (0) (0-2)0-18,059

(2-3)

30,088-33,431

(5-6)

65,340-66,000

Year

9 

Shallow (13-15)

1,350-1,500

(9-10)

279-310 0 (0) (0-1)

0-13,651 (0) (0-1)

0-11,000

Deep (45-50)

6,750-7,500

(21-24)

642-713 (6-8) (0-1)0-1800

(0-1)

0-8,688

(2-3)

31,056-34,507

(5-6)

65,340-66,000

Year

10

Shallow (10-12)

1,080-1,200

(9-10)

279-310 0 (0) (0-2)0-22,362

(0-1)

0-3407 (0)

Deep (50-55)

7,200-8,000

(21-24)

642-713 (8-10) (0) (0-1)0-11,113

(2-3)

26,210-29,122

(5-6)

65,340-66,000

Totals (485-590) 

68,477-82,750

(322-419)

10,057-

12,542

(61-87) (0-7) 

0-21,000

(9-45) 

112,594-433,099

(26-44) 

311,102-417,415

(47-65) 

572,320-715,000
Tables-28 Tables

Table 3.2-1. Projected Range of Activity Levels of Acoustic Geophysical Activities for Oil and Gas 

Exploration in the Area of Interest Over the 10-Year Time Period (numbers of surveys) and 

Survey Line Distance (miles) (continued)

Year Water 

Depth

Eastern Planning Area

HRG VSP SWD 2D 3Da WAZb 4D

Year

1 

Shallow (0-2)

0-100

(0-1)

0-31 (0) (0) (0) (0) (0)

Deep (0) (0-2)

0-62 (0) (0-1)

0-200

(0-1)

0-2,131 (0) (0)

Year

2 

Shallow 0-(2)

0-100 (0) (0) (0) (0) (0) (0)

Deep (0-1)

0-50

(0-1)

0-400 (0) (0-1)

0-400

(0-1)

0-4,599 (0) (0)

Year

3 

Shallow (0-1)

0-50

(0-1)

0-31 (0) (0) (0) (0) (0)

Deep (0-2)

0-100

(0-2)

0-62 (0) (0-1)0-20,900

(0-1)

0-4,599 (0) (0)

Year

4 

Shallow (0) (0) (0) (0) (0) (0) (0)

Deep (1-2)

50-100

(0-1)

0-5 (0) (0-1)0-26,900

(0-1)

0-11,200

(0-1)

0-12,456 (0)

Year

5 

Shallow (0) (0) (0) (0) (0) (0) (0)

Deep (0-1)

0-50

(0-1)

0-5 (0) (0-1)0-10,400

(0-1)

0-16,800 (0) (0)

Year

6 

Shallow (0) (0) (0) (0) (0) (0) (0)

Deep (1-2)

90-100

(0-1)

0-0.5 (0) (0) (0-1)0-16,800 (0) (0)

Year

7 

Shallow (0) (0) (0) (0) (0) (0) (0)

Deep (2-3)

135-150

(0-1)

0-0.5 (0) (0-1)0-900

(0-1)

0-11,200

(0-1)

0-2,945 (0)

Year

8 

Shallow (0) (0) (0) (0) (0) (0) (0)

Deep (2-4)

180-200

(0-1)

0-5 (0) (0-1)0-21,500

(0-1)

0-11,200

(0-1)

0-4,828 (0)

Year

9 

Shallow (0) (0) (0) (0) (0) (0) (0)

Deep (2-4)

180-200

(0-1)

0-0.5 (0) (0-1)0-27,400

0-(1)

0-11,200

(0-1)

0-4,973 (0)

Year

10

Shallow (0) (0) (0) (0) (0) (0) (0)

Deep (2-4)

180-200

(0-1)

0-5 (0) (0-1)0-10,000

(0-1)

0-11,200 (0) (0)

Totals (10-28) 

815-1,400

(0-14) 

0-607.5 (0) (0-9) 

118,600

(0-10) 

0-100,929

(0-4) 

0-25,202 (0)

2D = two-dimensional; 3D = three-dimensional; 4D = three-dimensional time-lapse; ft = foot; HRG = high-resolution geophysical; 

m = meter; SWD = seismic while drilling; VSP = vertical seismic profile; WAZ = wide azimuth (survey).

Shallow = <200-m (656-ft) water depth; Deep = >200-m (656-ft) water depth. 

Numbers in parentheses represent the number of surveys; numbers without parentheses represent the distance in miles.

a 3D surveys include ocean bottom cable and nodal surveys, vertical cable surveys. b WAZ estimates include coil shooting (exclusive to WesternGeco).
Gulf of Mexico G&G Activities Programmatic EIS Tables-29

Table 3.2-2. Projected Activity Levels of Non-Acoustic and Geological Activities for Oil and Gas Exploration in the Area of Interest Over the 

10-Year Time Period (numbers of surveys) and Survey Line Distance (miles) or Cores

Year

Western Planning Area Central Planning Area Eastern Planning Area

Geologic 

Coring CSEM Drilling Test1

Geologic 

Coring CSEM Drilling Test1

Geologic 

Coring CSEM Drilling Test1

Year 1 0 0 0 (2)

20 cores

(1)

760 miles 0 (1)15 cores 0 0 

Year 2 0 (1)

660 miles 0 (3)80 cores

(2)

1,520 miles 0 (2)30 cores 0 0 

Year 3 (1)

10 cores 0 0 (4)90 cores 0 0 (2)30 cores 0 0 

Year 4 0 0 0 (2)

20 cores

(1)

760 miles 0 (2)80 cores 0 0 

Year 5 (1)

40 cores

(1)

660 miles 0 (2)60 cores 0 0 0 (1)460 miles 0 

Year 6 0 (1)

660 miles 0 (2)20 cores

(1)

760 miles 0 (2)30 cores 0 0 

Year 7 0 0 (1)

1 well 0 0 0 0 0 0 

Year 8 0 0 0 (5)

95 cores 0 0 (2)30 cores 0 0 

Year 9 (2)

20 cores

(1)

660 miles 0 0 (1)760 miles

(1)

1 well 0 (1)460 miles 0 

Year 10 0 0 0 (5)

95 cores 0 0 (2)30 cores 0 0 

Totals (4)

70 cores

(4)

2,640 miles

(1)

1 well

(25)

480 cores

(6)

4,560 miles

(1)

1 well

(13)

245 cores

(2)

920 miles 0 

CSEM = controlled-source electromagnetic.

Typically, one OCS block is 9 square miles (23.3 square kilometers, 2,331 hectares, or 5,760 acres).

1 Penetration <150 meters (500 feet).
Tables-30 Tables

Table 3.2-3. Projected Activity Levels of Geological and Geophysical Activities for Renewable Energy Site Characterization and Assessment in 

the Area of Interest Over the 10-Year Time Period

Renewable 

Energy Area

OCS Blocks 

Equivalent

HRG Surveys1

(hours Line 

Miles) 

2D or 3D 

Deep-Penetration 

Seismic

Geotechnical Surveys2

Bottom-founded 

Monitoring Buoys 

(min.-max.)

CPT 

(min.-max.)

Geologic 

Coring 

(min.-max.)

Grab 

Samples 

(min.-max.)

Wind Energy 6 (920)

3,472 0 84-270 87-270 87-270 1-2 

Alternate Use 0 0 0 0 0 0 0

Total 6 (920)

3,472 0 84-270 84-270 84-270 1-2 

2D = two-dimensional; 3D = three-dimensional; CPT = cone penetrometer test; HRG = high-resolution geophysical; max = maximum; 

min = minimum; OCS = Outer Continental Shelf.

1 HRG survey effort per block was assumed to be 500 nautical miles (925 kilometers), requiring 150 hours to complete. Added 20 nautical miles 

(23 miles; 37 kilometers) and 20 hours for surveying one transmission cable route (USDOI, BOEM, 2012).

2 Geotechnical survey effort was estimated to be 14-45 sampling locations per block based on the potential range of wind turbine densities per 

block (assuming one sampling location per turbine location).
Gulf of Mexico G&G Activities Programmatic EIS Tables-31

Table 3.2-4. Projected Activity Levels of Geological Surveys for Outer Continental Shelf Marine Minerals Projects in the Area of Interest Over the 

10-Year Time Period

Year Project State Cycle Volume 

(yd3)

Depth 

(m)

Distance 

Offshore (km) Vibracores Jet Probes

Grab 

Samples

Western Planning Area

Year 2 to 

Year 5 East Texas Coast TX 5,000,000 7-10 24 45 0 40

Central Planning Area

Year 1 North Breton Island LA 4,000,000 3-6 5.5-7.5 36 0 0

Year 2 to 

Year 5

Terrebonne Basin Barrier Shoreline 

Restoration LA 6,000,000 4-7 15 90 0 0 

Cameron Parish Shoreline Restoration 

(east of Calcasieu Pass) LA 5,000,000 7-10 27 45 0 0 

Alabama Coast AL 6,000,000 9-15 5.5-10 54 0 50

Eastern Planning Area

Year 2 to 

Year 5

Manatee, Sarasota, and or Charlotte 

County (Sarasota, Manasota, and Captiva 

Ridge Fields)

FL 1,500,000 10-20 16-24 23 10 0 

Lee County (Captiva Ridge Field, Sanibel 

Island Ridge Field) FL 1,500,000 10-20 16-24 23 10 0 

Year 6 to 

Year 8

Pinellas County (Sand Key Ridge Field) FL 2,000,000 10-20 16-24 30 10 0

Manatee, Sarasota, Charlotte (Sarasota, 

Manasota, and Captiva Ridge Fields) FL 1,500,000 10-20 16-24 23 10 0 

Lee (Captiva Ridge Field, Sanibel Island 

Ridge Field) FL 1,500,000 10-20 16-24 23 10 0 

Total 34,000,000 392 50 90

AL = Alabama; FL = Florida; km = kilometers; LA = Louisiana; m = meters; TX = Texas; yd3 = cubic yards.
Tables-32 Tables

Table 3.2-5. Projected Activity Levels of Geophysical Surveys for Marine Minerals Projects in the Area of Interest Over the 10-Year Time Period

Timeframe Project State

Cycle 

Volume 

(yd3

) 

Depth 

(m)

Distance 

Offshore 

(km)

Prospecting 

HRG1

Pre-Dredge 

HRG1 Post-Dredge HRG2

Line 

Miles

Duration 

(hours)

Line 

Miles

Duration 

(hours)

Line 

Miles

Duration 

(hours)

Western Planning Area

Year 4 to 

Year 6 East Texas Coast TX 5,000,000 7-10 24 63.4 12.2 83.9 16.2 83.9 16.2

Central Planning Area

Year 1 to 

Year 3

Caminada Headland 

(Increment 2) LA 6,100,000 6-7 15 0.0 0.00 0.0 0.0 133.8 25.85

Caillou Headlands 

(Whiskey Island) 

Restoration

LA 5,300,000 6-7 15 0.0 0.0 0.0 0.0 121.4 23.4

North Breton Island LA 5,000,000 3-6 5.5-7.5 63.4 12.2 126.8 24.5 126.8 24.5

Mississippi Coastal 

Improvements 

Program – Gulf 

Islands Restoration

MS 11,000,000 9-15 8-10 0.0 0.0 0.0 0.0 87.2 16.8

Year 4 to 

Year 6

Terrebonne Basin 

Barrier Shoreline 

Restoration 

LA 6,000,000 4-7 15 76.1 14.7 0.0 0.0 0.0 0.0

Cameron Parish 

Shoreline Restoration 

(East of Calcasieu 

Pass)

LA 4,000,000 7-0 27 50.7 9.8 83.9 16.2 83.9 16.2

Alabama Coast AL 5,000,000 9-15 5.5-10 63.4 12.2 0.0 0.0 0.0 0.0

Year 7 to 

Year 10

Terrebonne Basin 

Barrier Shoreline 

Restoration 

(continued)

LA 6,000,000 4-7 15 0.0 0.0 259.3 50.1 259.3 50.1

Alabama Coast 

(continued) AL 5,000,000 9-15 5.5-10 0.0 0.0 71.3 13.8 71.3 13.8

Eastern Planning Area

Year 1 to Long Boat Key FL 500,000 10-15 20 0.0 0.0 5.7 1.1 5.7 1.1
Table 3.2-5. Projected Activity Levels of Geophysical Surveys for Marine Minerals Projects in the Area of Interest Over the 10-Year Time Period 

(continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-33

Timeframe Project State

Cycle 

Volume 

(yd3

) 

Depth 

(m)

Distance 

Offshore 

(km)

Prospecting 

HRG1

Pre-Dredge 

HRG1 Post-Dredge HRG2

Line 

Miles

Duration 

(hours)

Line 

Miles

Duration 

(hours)

Line 

Miles

Duration 

(hours)

Year 3 Collier County (Toms 

Hill) FL 600,000 15-18 25 0.0 0.0 5.2 1.0 5.2 1.0

Year 4 to 

Year 6

Manatee, Sarasota, 

and or Charlotte 

County (Sarasota, 

Manasota, and 

Captiva Ridge Fields)

FL 1,500,000 10-20 16-24 19.0 3.7 14.3 2.8 14.3 2.8

Lee County (Captiva 

Ridge Field, Sanibel 

Island Ridge Field)

FL 1,500,000 10-20 16-24 19.0 3.7 14.3 2.8 14.3 2.8

Year 7 to 

Year 10

Pinellas County (Sand 

Key Ridge Field) FL 2,000,000 10-20 16-24 25.4 4.9 19.0 3.7 19.0 3.7

Manatee, Sarasota, 

Charlotte (Sarasota, 

Manasota, and 

Captiva Ridge Fields)

FL 1,500,000 10-20 16-24 19.0 3.7 14.3 2.8 14.3 2.8

Lee County (Captiva 

Ridge Field, Sanibel 

Island Ridge Field)

FL 1,500,000 10-20 16-24 19.0 3.7 14.3 2.8 14.3 2.8

Collier County (Toms 

Hill) FL 600,000 15-18 25 0.0 0.0 5.2 1.0 5.2 1.0

Total 68,100,000 N/A N/A 418.4 80.8 717.5 138.8 1,059.9 204.9

AL = Alabama; FL = Florida; HRG = high-resolution geophysical; km = kilometers; LA = Louisiana; m = meters; N/A = not available; OCS = Outer 

Continental Shelf; TX = Texas; yd3 = cubic yards.

1 Prospecting and pre-dredge HRG involves the use of subbottom profiler, side-scan sonar, bathymetry (echosounders), and magnetometer.

2 On-lease typically involves only a bathymetry (echosounders).
Tables-34 Tables

Table 3.2-6. Characteristics of the Proposed Geological and Geophysical Activities Scenario in the Area of Interest Over the 10-Year Time 

Period

Activity Type Purpose

Number of 

Surveys 

or Level of 

Effort

Primary 

Platform and 

Size

Scale of 

Activity

Penetration 

Depth

Approximate 

Duration/ Event

Shore 

Base1

Service 

Vessel

High-Energy 

Sound 

Source(s)

Bottom 

Area 

Disturbed

Oil and Gas Exploration

HRG 

(Airgun or 

Non-Airgun) 

Seismic 

Survey

Shallow 

hazards 

assessment 

and 

archaeological 

determinations

550-716 1 ship,

~30 m

103,025 line 

mi

10s to 100s 

of m

3 days - 

1 week 1 0 

• 1-2 airguns

• Boomer, 

sparker, or 

CHIRP 

subbottom 

profiler

• Side-scan 

sonar

• Multi-beam 

depth 

sounder

0 

Vertical 

Seismic 

Profiling/

Checkshot

Calibrate 

seismic with 

known geology

397-561 1 ship,

~30 m

16,962 line 

mi

100s to 

1,000s of m 3-4 days 1 0 Single airgun 0 

Seismic 

While Drilling

Monitor drilling 

for transition 

zones, etc.

61-100 Well platform ≥1/16 OCS 

block

100s to 

1,000s of m

Intermittent; up 

to 6 months 0-1 0 Airgun Wellbore

2D Seismic 

Survey

Identify 

geologic 

structure

0-23 1 ship,

~100 m

149,800 line 

mi

kms to 

10s of kms 2-12 months 0-1 0-1 Airgun array 0 

3D Seismic 

Survey

Identify 

geologic 

structure

9-69 1-2 ships, 

~100 m

649,420 line 

mi

kms to 

10s of kms 4-12 months 0-1 0-1 Dual airgun array

0 

WAZ and 

Related 

Multi-Vessel

Better define 

complex 

geologic 

structure

28-62 4-6 ships, 

~100 m

561,432 line 

mi

kms to 

10s of kms 1 year 0-2 1-2 4 arrays 0 
Table 3.2-6. Characteristics of the Proposed Geological and Geophysical Activities Scenario in the Area of Interest Over the 10-Year Time Period

(continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-35

Activity Type Purpose

Number of 

Surveys or 

Level of 

Effort

Primary 

Platform and 

Size

Scale of 

Activity

Penetration 

Depth

Approximate 

Duration/ 

Event

Shore 

Base1

Service 

Vessel

High-Energy 

Sound 

Source(s)

Bottom Area 

Disturbed

4D Seismic

Survey

Monitor change 

in oil and gas 

reservoirs

57-101 1-2 ships, 

~100 m

1,108,37

8 line mi

kms to 

10s of kms 4-12 months 0-1 0-1 Dual airgun array

0 

CSEM

Optimize 

reservoir 

identification

≤12 1 ship,

~20 100 m 8,120 mi 3-5 km 1-6 months 0-1 0-1 0 

Anchors with 

bottom 

receivers, <1 

OCS block

Gravity and 

Magnetic

Passive 

measurement, 

gravity and 

magnetic fields

0-3 

Acquisition 

with seismic 

typical

100s to 

1,000s of 

line km

kms to 

10s of kms 4-12 months 0-1 0-1 0 0 

Aeromagnetic

Passive 

measurement, 

magnetic fields

0-1 1 aircraft

100s to 

1,000s of 

line kms

kms to 

10s of kms 1-3 months 0-1 0 0 0 

CPT

Measure 

sediment 

engineering 

properties

≤1 event 

(100 tests)

1 

barge/ship, 

~60 m

≥1/16 

OCS 

block or 

along 

cable 

route to 

shore

<10 m <3 days 1 0 0 ~10 m2

/ 

sample

Corings Extract 

sediment core

≤42 events 

(795 cores)

1 

barge/ship, 

~20 m

<1/16 

OCS 

block

<300 m <3 days 0-1 0 0 ~10 m2

/ 

sample

Grab 

Sampling

Collect 

sediment and 

benthic fauna

0-1 

1 

barge/ship, 

~60 m

<1/16 

OCS 

block

<1 m <3 days 1 0 0 ~10 m2

/ 

sample

Shallow Drill 

Test Wells

Test drilling 

outside of lease 

program

≤2 wells

Platform or 

drillship, 

~100 m 

<1/16 

OCS 

block

<150 m 5-30 days 0-1 0-2 0 ≤2 ha well
Table 3.2-6. Characteristics of the Proposed Geological and Geophysical Activities Scenario in the Area of Interest Over the 10-Year Time Period 

(continued)

Tables-36 Tables

Activity Type Purpose

Number of 

Surveys or 

Level of 

Effort

Primary 

Platform and 

Size

Scale of 

Activity

Penetration 

Depth

Approximate 

Duration/ 

Event

Shore 

Base1

Service 

Vessel

High-Energy 

Sound 

Source(s)

Bottom 

Area 

Disturbed

COST Well

Test drilling 

outside of lease 

program

≤1 well

Platform or 

drillship, 

~100 m

<1/16 

OCS block ≥150 m 5-30 days 0-1 0-2 0 ≤2 ha/well

Renewable Energy

HRG Survey

Shallow hazards 

assessment and 

archaeological 

determinations

≤1 survey 1 ship, 

~20-30 m

Each 

survey 

≥1/16 

OCS2

block plus 

cable 

route to 

shore; 

total 

5,587 km 

(6 OCS 

blocks)

Surficial to 

10s to 100s 

of meters

3 days - 

1 weeks 1 0 

• Boomer, 

sparker, or 

CHIRP 

subbottom 

profiler

• Side-scan 

sonar

• Multi-beam 

depth 

sounder

0 

CPT

Measure 

sediment 

engineering 

properties

≤1 event 

(270 tests)

1 

barge/ship, 

~60 m

≥1/16 

OCS block 

or along 

cable 

route to 

shore

<10 m 9 days 1 0 • 0 ~10 m2

/ 

sample

Corings Extract 

sediment core

≤1 event 

(270 cores)

1 

barge/ship,

~60 m

≥1/16 

OCS block 

or along 

cable 

route to 

shore

<300 m 9 days 1 0 0 ~10 m2

/ 

sample

Grab 

Sampling

Collect sediment 

and benthic 

fauna

≤1 event 

(270

samples)

1 

barge/ship, 

~60 m

≥1/16 

OCS block 

or along 

cable 

route to 

shore

<1 m 9 days 1 0 0 ~10 m2

/ 

sample

BottomFounded 

Monitoring 

Buoy

Measure ocean 

and 

meteorological 

conditions

≤1 event 

(2 buoys)

1 

barge/ship, 

~20 m

≥1/16 

OCS block Surficial <3 days 1-2 0 0 ~1 m2

/ 

buoy
Table 3.2-6. Characteristics of the Proposed Geological and Geophysical Activities Scenario in the Area of Interest Over the 10-Year Time Period 

(continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-37

Activity Type Purpose

Number of 

Surveys or 

Level of 

Effort

Primary 

Platform and 

Size

Scale of 

Activity

Penetration 

Depth

Approximate 

Duration/ 

Event

Shore 

Base1

Service 

Vessel

High-Energy 

Sound 

Source(s)

Bottom 

Area 

Disturbed

Marine Minerals

HRG Survey

Shallow hazards 

assessment and 

archaeological 

determinations

≤18 events, 

~47 days

1 ship, 

~30 m 

~3,533 

line km

10s to 100s 

of m

3 days - 

2 weeks 1 0 

• Boomer, 

sparker, or 

CHIRP 

subbottom 

profiler

• Side-scan 

sonar

• Multi-beam 

echosounder

0 

Grab 

Sampling

Collect sediment 

and benthic 

fauna

≤2 events 

(90 grabs)

1 

barge/ship, 

~20 m

≥1/16 

OCS block <1 m <3 days 1 0 0 ~10 m2

/ 

sample

Vibracoring Extract 

sediment core

≤10 events 

(392 cores)

1 

barge/ship, 

~20 m

≥1/16 

OCS block 10-15 m 3-5 days 1 0 0 ~10 m2

/ 

sample

Jet Probe Extract 

sediment core

≤5 events 

(50 probes)

1 

barge/ship, 

~20 m

≥1/16 

OCS block 10-15 m 3-5 days 1 0 0 ~10 m2

/ 

sample

2D = two-dimensional; 3D = three-dimensional; 4D = four-dimensional (three-dimensional time-lapse); CHIRP = compressed high-intensity radiated pulse; 

COST = continental offshore stratigraphic test; CPT = cone penetrometer test; CSEM = controlled source electromagnetic; ha = hectares; HRG = high-resolution 

geophysical; km = kilometer; m = meters; m2 = square meters; mi = mile; OCS = Outer Continental Shelf; WAZ = wide azimuth (survey). 1 Shore base is the point of deployment to return berth. 2 1/16 of an OCS block (256 ac) is the smallest area considered for renewable energy leasing.
Tables-38 Tables

Table 3.2-7. Summary of All Projected Maximum Activity Levels of Geological and Geophysical Activities 

in the Area of Interest Over the 10-Year Time Period for the Oil and Gas, Renewable 

Energy, and Marine Minerals Program Areas (sum of survey activities from Tables 3.2-2 

through 3.2-6) 

Activity Units Oil & Gas Renewable Minerals Totals

Geophysical

HRG Surveys

(Airgun and Non-Airgun)

# of Surveys 716 1 18 735

Line Miles 103,025 3,472 2,196 108,693

VSP Surveys # of Surveys 561 0 0 561

Line Miles 16,992 0 0 16,962

SWD Surveys # of Surveys 100 0 0 100

Line Miles 0 0 0 0

2D Surveys # of Surveys 23 0 0 11

Line Miles 149,800 0 0 149,800

3D Surveys # of Surveys 69 0 0 60

Line Miles 649,420 0 0 649,420

WAZ Surveys # of Surveys 62 0 0 58

Line Miles 561,432 0 0 561,432

4D Surveys # of Surveys 101 0 0 101

Line Miles 1,108,378 0 0 1,108,378

Total 3D, WAZ, 4D Survey # of Surveys 232 0 0 219

Line Miles 2,319,230 0 0 2,319,230

CSEM # of Surveys 12 0 0 12

Line Miles 8,120 0 0 8,120

Geological

Bottom Sampling

CPT Number 100 270 0 370

Corings Number 795 270 0 1,065

Grab Sample Number 1 270 90 361

Vibracores Number 0 0 392 392

Jet Probe Number 0 0 50 50

Bottom Sampling Subtotal Number 896 810 532 2,238

Bottom Impacts (10 m2/sample) m2 8,960 8,100 5,320 22,380

Shallow Drill Test Wells Number 2 0 0 2

COST Wells Number 1 0 0 1

Bottom Impacts (20,000 m2/well) m2 60,000 0 0 60,000

Other

Bottom-Founded Monitoring Buoy Number 0 2 0 2

Bottom Impacts 

(Footprint 0.56 m2/buoy + 

Sweep 34,000 m2/buoy)

m2 0 68,001 0 68,001

Total Bottom Impacts m2 150,381

2D = two-dimensional; 3D = three-dimensional; 4D = four-dimensional; COST = Continental Offshore 

Stratigraphic Test; CPT = cone penetrometer test; CSEM = controlled source electromagnetic; 

HRG = high-resolution geophysical; m2

 = square meters; SWD = seismic while drilling; VSP = vertical 

seismic profile; WAZ = wide azimuth (survey).
Gulf of Mexico G&G Activities Programmatic EIS Tables-39

Table 3.3-1. Impact-Producing Factor Descriptions

Impact-Producing Factor Survey Type(s) Brief Description

Active Acoustic Sound Sources

• Airguns

Deep-penetration seismic 

surveys and HRG surveys

Underwater noise from compressed 

air release

• Electromechanical Sources HRG surveys 

Underwater noise from subbottom 

profilers (boomer, sparker, or CHIRP), 

side-scan sonar, and multi-beam 

echosounders

Vessel and Equipment Noise

All vessel surveys; drilling 

of COST wells and shallow 

test wells

Underwater noise from vessel 

engines and equipment, and from 

drilling activities

Vessel Traffic All vessel surveys Vessel movements including survey 

lines and round trips to onshore base

Aircraft Traffic and Noise Aeromagnetic surveys Aircraft traffic, and noise from engines 

and propellers

Stand-Off Distances

Deep-penetration seismic 

airgun surveys with towed 

streamers

Temporary exclusion zone around 

streamer arrays to avoid 

entanglement

Vessel Discharges All vessel surveys Bilge, ballast, sanitary, and domestic 

waste discharges

Trash and Debris All vessel surveys Accidental release of trash or debris 

into the ocean

Seafloor Disturbance

• Bottom Sampling

Geotechnical sampling and 

testing

Collection of vibracore, geologic core, 

and grab samples; CPT testing

• Cables, Nodes, and Anchors

Certain deep-penetration 

seismic airgun surveys and 

CSEM and MT surveys

Temporary placement of cables, 

nodes, sensors, or anchors on or in 

the seafloor

• COST Wells and Shallow 

Test Drilling

Drilling of COST wells and 

shallow test wells

Seafloor disturbance due to 

placement of well template, jetting of 

well, and anchoring of drilling rig

• Monitoring Buoys Site characterization for 

renewable energy areas

Temporary anchoring of monitoring 

buoys

Drilling Discharges Drilling of COST wells and 

shallow test wells

Release of drilling fluids and cuttings 

at the seafloor and from drilling rigs

Entanglement 

Certain deep-penetration 

seismic airgun surveys 

using OBCs and OBNs

Temporary placement of cables, 

nodes, sensors, or anchors on or in 

the seafloor

Accidental Fuel Spills All vessel surveys Potential for release of diesel or fuel 

oil from a vessel accident

CHIRP = compressed high-intensity radiated pulse; COST = Continental Offshore Stratigraphic Test; 

CPT = cone penetrometer test; CSEM = controlled source electromagnetic; HRG = high-resolution 

geophysical; MT = magnetotelluric; OBC = ocean bottom cable; OBN = ocean bottom node. 
Tables-40 Tables

Table 3.3-2. Characteristics of Active Acoustic Sound Sources Included in the Proposed Action

Source Usage

Typical 

Operating 

Frequenciesa

Broadband 

Source Levelzero-to-peak

(dB re 1 μPa at 1 m)b

Large Airgun Array 

(8,000 in3

) 

Deep-penetration 

seismic surveys, oil and 

gas exploration (2D, 3D, 

WAZ, VSP, 4D, etc.)

10-2,000 Hz

(most energy

at <500 Hz)

248.1

Small Airgun Array 

(90 in3

) HRG surveys

10-2,000 Hz

(most energy

at <600 Hz)

227.7

Pinger HRG surveys 2,000 Hz --

Sparker HRG surveys 50-4,000 Hz 212

Boomer HRG surveys 300-3,000 Hz 203.3

CHIRP Subbottom Profiler HRG surveys 0.5-24 kHz 203

Side-Scan Sonar HRG surveys 16-1,500 kHz 213

Single-Beam Echosounder HRG surveys 12-240 kHz 195-205

Multi-Beam Echosounder HRG surveys 50-400 kHz 206

2D = two-dimensional; 3D = three-dimensional; 4D = four-dimensional; CHIRP = compressed 

high-intensity radiated pulse; dB re 1 μPa at 1 m = decibels referenced to 1 micropascal at 1 meter; 

HRG = high-resolution geophysical; Hz = hertz; in3 = cubic inches; kHz = kilohertz; VSP = vertical seismic 

profile; WAZ = wide azimuth (survey).

a Operating frequencies obtained from Appendix F. b Source level obtained from Appendix D. 

-- Not applicable; a pinger is not broadband.
Gulf of Mexico G&G Activities Programmatic EIS Tables-41

Table 3.3-3. Vessel and Helicopter Traffic Associated with the Proposed Action

Survey Type Projected 

Vessel-Months1

Estimated 

Transits to Shore 

Base for Survey 

Vessels

Estimated 

Transits to Shore 

Base for Service 

Vessels

Estimated 

Helicopter Transits 

Needed to Support 

Surveys

Vessel Based (2D, 

3D, 4D, WAZ) 3,446 328 19,368 7,329

Platform Based 

(VSP, SWD) 66 165 19 168

Vessel Based 

(Non-Airgun HRG) 72 288 0 0 

Other 17 24 107 0

Oil and Gas G&G Activities Subtotal 805 19,494 7,497

HRG 0.18 5 0 0

Sampling 0.1 27 0 0

Bottom-Founded 

Buoy 0.1 2 0 0 

Renewable Energy G&G Activities 

Subtotal 34 0 0 

HRG 18 90 0 0

Sampling 2 4 0 0

Vibracore/Jet 15 60 0 0

Marine Minerals G&G Activities Subtotal 154 0 0

Combined Total Transits 993 19,689 7,497

2D = two-dimensional; 3D = three-dimensional; 4D = four-dimensional; G&G = geological and 

geophysical; HRG = high-resolution geophysical; SWD = seismic while drilling; VSP = vertical seismic 

profile; WAZ = wide azimuth (survey).

1 Vessel months are used as a measure of vessel utilization, or vessel activity, necessary to complete the 

data acquisition. Vessel months were calculated by multiplying the projected number of survey events 

times the mean number of vessels used in that survey type times the mean duration of that survey type.
Tables-42 Tables

Table 3.4-1. Cumulative Scenario Activities that Include Coincident Impact-Producing Factors with the Proposed Action Geological and 

Geophysical Activities

Cumulative Scenario Component 

and Associated Activities

Impact-Producing Factor

Active Acoustic Sound SourcesVessel and Equipment NoiseVessel TrafficAircraft Traffic and NoiseStand-Off DistanceVessel DischargesTrash and DebrisSeafloor DisturbanceDrilling DischargesEntanglementAccidental Fuel Spill

Federal OCS Programs

Oil and Gas Exploration and Development - + + + + + + + + - +

Decommissioning - + + - + + + + - - +

Renewable Energy Development - + + - + + + + - - +

Marine Minerals Use - + + - + + + + - - +

Oil and Gas Activities in State Water

Oil and Gas Exploration and Development + + + + + + + + + + +

Decommissioning - + + - + + + + - - +

Other Major Factors Influencing the AOI

Deepwater Ports - + + - + + + - - - +

Commercial and Recreational Fishing + + + - + + + + - + +

Shipping and Marine Transportation - + + - - + + - - - +

Dredged Material Disposal - + + - + + + + - - +

Existing, Planned, and New Cable Infrastructure + + + - + + + + - - +

Military Activities + + + + + + + + - - +

Scientific Research + + + + - + + + - + +

Maintenance Dredging and Federal Channels - + + + + + + + - - +

Coastal Restoration Programs - + + - + + + + - - +

Mississippi River Hydromodification and Subsidence - + + - - + + - - - +

Extreme Climatic Events - - - - - - - + - - +

Climate Change and Sea-Level Rise - - - - - - - - - - -

Natural Oil Seeps - - - - - - - - - - +

AOI = Area of Interest; OCS = Outer Continental Shelf; “+” = the activity includes coincident impact-producing factors; and “-” = the activity does 

not include coincident impact-producing factors.
Gulf of Mexico G&G Activities Programmatic EIS Tables-43

Table 3.4-2. Summary of Oil and Gas Exploration and Development Activities in the U.S. Gulf of Mexico Projected 10-Year Projections (bold) 

(based on 40-year projections [not bold] [Modified from: USDOI, BOEM, 2015d, 2016b])

Activity 10-Year Projections 40-Year Projections (2012-2051) Used as Basis

WPA CPA EPA Total OCS WPA CPA EPA Total OCS

Wells Drilled

Exploration and Delineation Wells 295-423 1,430-2,028 3-7 1,728-2,457 1,180-1,690 5,720-8,110 10-27 6,910-9,827

Development and Production Wells 363-530 1,770-2,505 0-10 2,133-3,045 1,450-2,120 7,080-10,020 0-40 8,530-12,180

Producing Oil Wells 124-184 700-961 0-6 824-1,151 495-737 2,801-3,843 0-25 3,296-4,605

Producing Gas Wells 196-288 887-1,289 0-3 1,084-1,580 785-1,153 3,549-5,157 0-10 4,334-6,320

Production Structures

Installed 64-96 295-410 0-1 359-507 255-384 1,180-1,640 0-2 1,435-2,026

Decommissioned Using Explosives 40-60 177-252 0 217-312 160-240 707-1,006 1 868-1,247

Total Decommissioned 58-88 262-371 0-1 320-459 233-350 1,046-1,485 0-2 1,279-1,837

Method of Transportation

Percent Piped N/A N/A N/A N/A 84->99 93->99 N/A 92->99

Percent Barged N/A N/A N/A N/A <1 >1 N/A <1

Percent Tankered N/A N/A N/A N/A 0-15 0-6 N/A 0-7

Length of Installed Pipelines (km) 1,306-3,085 6,301-14,294 0-58 7,607-17,437 5,224-12,339 25,204-57,177 0-233 30,428-69,749

Vessel and Helicopter Traffic

Service Vessel Trips 

(round-trips × 103) 120-180 707-907 0-9 828-1,096 481-720 2,829-3,627 0-35 3,310-4,382

Helicopter Operations (× 103) 1,305-2,613 5,945-11,125 0-16 7,178-13,901 5,220-10,450 23,780-44,500 0-655 28,710-55,605

CPA = Central Planning Area; EPA = Eastern Planning Area; km = kilometers; N/A = not available; OCS = Outer Continental Shelf; 

WPA = Western Planning Area.
Tables-44 Tables

Table 3.4-3. Structure Removal Permit Applications on the Area of Interest, 2004 to 2015 (Modified from: 

USDOI, BSEE, 2017) 

Final Disposition 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015* Total %

Scrapping/Shore 144 118 164 124 176 237 223 352 282 186 198 115 2,319 83.3

Reuse 2 2 1 19 16 4 3 1 16 13 18 2 97 3.5

Rigs-to-Reefs 8 21 20 34 35 40 53 40 28 36 36 18 369 13.2

Total 154 141 185 177 227 281 279 393 326 235 232 135 2,785 100

*Data through January 27, 2016. 

% = percent.

Table 3.4-4. Structures Removed from the Area of Interest, 2004 to 2015 (Modified from: USDOI, 

BSEE, 2017) 

Structure Type 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015* Total %

Caissons 101 41 52 60 59 80 57 113 98 99 84 38 882 38.2

Platforms 64 65 46 82 74 129 142 152 147 105 88 70 1,164 50.4

Mobile Offshore 

Production Units 0 0 0 1 1 0 0 0 0 0 0 0 2 0.07

Mini-Tension 

Leg Platforms 0 0 1 0 0 0 0 0 0 0 0 0 1 0.03

Well Protectors 29 17 16 17 19 25 19 28 38 18 29 5 260 11.3

Total 194 123 115 160 153 234 218 298 283 216 201 113 2,309 100

*Data through January 27, 2016. 

% = percent.
Gulf of Mexico G&G Activities Programmatic EIS Tables-45

Table 3.4-5. Summary of Annual Oil and Gas Production from State Waters of Several Gulf Coast States 

(From: Louisiana Department of Natural Resources, 2017; Railroad Commission of Texas, 

2017; Geological Survey of Alabama, State Oil and Gas Board, 2017) 

State Year Crude Oil (bbl) Natural Gas (MMcf)

Louisiana

2009 3,858,277 70,811,813

2010 4,671,151 62,296,972

2011 5,064,106 63,099,986

2012 5,036,472 71,866,441

2013 5,584,262 58,666,623

2014 5,551,263 42,805,939

2015 5,246,644 32,625,158

2016 4,952,376 24,619,857

Texas*

2009 229,984 85.9

2010 209,923 63.4

2011 416,639 834.3

2012 272,226 443.3

2013 375,106 14.8

2014 384,040 445,5

2015 271,665 207.3

2016 148,233 48.7

Alabama**

2009 31,860 109,811

2010 34,585 102,052

2011 23,832 84,730

2012 12,116 87,875

bbl = barrels; MMcf = million cubic feet.

*Texas offshore data reported as crude oil and casinghead gas between 2009 and 2016; 2013 data 

reported as gas well gas and condensate.

**2014-2016 data were not publically available at the time this table was prepared.
Tables-46 Tables

Table 3.4-6. Summary of Deepwater Ports in the Area of Interest (Modified from: USDOT, MARAD, 2015a) 

Port Name Operator Comments Status

Louisiana 

Offshore Oil 

Port

Marathon 

Domestic 

LLC

On June 1, 2000, a deepwater port license was issued to the Louisiana Offshore Oil Port 

(LOOP), the only deepwater port petroleum terminal in existence. LOOP is located 25.7 km 

(16 mi) southeast of Port Fourchon, Louisiana. LOOP was built by a group of major oil and 

pipeline companies and has been operational since 1981. It serves as an unloading and 

distribution port for supertankers coming into the GOM. The petroleum is piped north to 

Lafourche Parish, where it is stored and piped to U.S. markets.

Operational

Port Dolphin Port Dolphin 

Energy LLC

On March 29, 2007, an application was filed with MARAD to construct a deepwater port located 

approximately 28 mi (45 km) offshore of Tampa, Florida. The applicant is a wholly owned 

subsidiary of Höegh LNG. The port will consist of two Submerged Turret Loading buoys. On 

October 26, 2009, MARAD issued a ROD approving, with conditions, the license application, and 

on April 19, 2010, the official license was issued. Port Dolphin is currently working with the 

relevant Federal and State agencies to obtain the required authorizations and permits for 

construction and operation of the facility. MARAD anticipated that construction of the Port 

Dolphin facility would commence in late 2014. As of January 2015, Port Dolphin has acquired 

certification to build its 67.6-km (42-mi) long pipeline from Port Manatee to the port terminal site. 

The Federal Energy Regulatory Commission has issued a certificate of public necessity and 

convenience to build and operate the pipeline.

Not 

operational

(industry 

sources 

indicate that 

the project 

has been 

abandoned)

Main Pass 

Energy Hub

Freeport 

McMoRan

A notice of revised application was submitted on June 22, 2006; the Main Pass Energy Hub 

represents a conversion of a sulfur/brine mining facility into an LNG terminal for regasification. 

The project was approved on November 20, 2007. The Main Pass Energy Hub is located 

25.7 km (16 mi) offshore Louisiana in Main Pass Block 299. Due to significant financial 

challenges, Freeport McMoRan has been unable to comply with the conditions of the ROD. On 

January 2, 2012, MARAD moved to rescind approval of the ROD for the project.

Not 

operational

Gulf 

Gateway 

Energy 

Bridge, LLC 

(Gulf 

Gateway)

Excelerate 

Energy 

Limited 

Partnership

Gulf Gateway, located off the coast of Louisiana, consists of a Submerged Turret Loading 

system (i.e., submerged turret buoy; chains, lines, and anchors; flexible riser; and subsea 

manifold). A ROD was issued on December 31, 2003, and the license was issued on May 26, 

2004. On February 22, 2012, Excelerate Energy notified MARAD and USCG of its intention to 

decommission the Gulf Gateway deepwater port due to irreparable hurricane damage to 

pipelines interconnecting with the deepwater port, as well as a changing natural gas market, 

which impacted the operator’s ability to receive consistent shipments. The MARAD approved 

the decommissioning and terminated the license for the Gulf Gateway deepwater port on 

June 28, 2013.

Not 

operational
Table 3.4-6 Summary of Deepwater Ports in the Area of Interest (Modified from: USDOT, MARAD, 2015a) (continued)

Gulf of Mexico G&G Activities Programmatic EIS Tables-47

Port Name Operator Comments Status

Bienville 

Offshore 

Energy 

Terminal

TORP 

Technology 

LP

Application filed on January 12, 2006, for an LNG facility to be located in the GOM, 101 km 

(63 mi) south of Mobile Point, Alabama. The facility consists of a HiLoad Unit, which is a 

floating structure connecting directly to the LNG carrier hull. On October 9, 2008, the applicant 

elected to withdraw its application in order to consider technical modifications to its proposed 

project. On October 29, 2010, MARAD approved, with conditions, the modified TORP Terminal 

deepwater port license application. The approval conditions required that TORP Terminal meet 

all financial responsibilities requirements of the Deepwater Port Act of 1974, as amended. 

Since issuance of the ROD, TORP Terminal has been unable to meet the financial 

responsibility conditions required for license issuance. As a result, the TORP Terminal 

applicant withdrew its deepwater port license application from the final licensing process and 

terminated all project activities. In response, MARAD acknowledged the withdrawal and 

rescinded the official ROD on June 18, 2012.

Not 

operational

Port Pelican Port Pelican, 

LLC

On November 25, 2002, an application was submitted for a deepwater port license to construct 

an LNG gravity-based structure facility off the coast of Louisiana. The Port Pelican Deepwater 

Port License was issued on January 20, 2004, the first deepwater port license to be issued for 

the construction and operation of an LNG facility. On July 11, 2005, Port Pelican LLC provided 

a letter to MARAD and USCG of its plans to place the project on an indefinite hold. On 

October 4, 2005, a Notice of Cancellation was published. On October 28, 2009, MARAD 

received notification from Port Pelican LLC of the relinquishment of its license. In response, 

MARAD published a notice on December 9, 2009, announcing the relinquishment of the license 

and cancellation of all actions related to the project. To date, the project remains closed with 

MARAD.

Project 

closed

Gulf Landing U.S. Gas & 

Oil, LLC

On November 3, 2003, an application was filed for the construction and operation of an 

offshore gravity-based structure to be located 61 km (38 mi) offshore Louisiana. On 

February 16, 2005, the ROD was issued, and on April 29, 2005, the official license was issued 

for Gulf Landing. However, in March 2007, Gulf Landing LLC announced its intention to 

terminate all project and construction activities for the proposed facility. On April 30, 2009, Gulf 

Landing LLC surrendered its deepwater port license. The MARAD accepted the license 

surrender and issued a license surrender notice on July 1, 2009 (Federal Register, 2009b).

Project 

closed

GOM = Gulf of Mexico; km = kilometers; LNG = liquefied natural gas; MARAD = Maritime Administration; mi = miles; ROD = Record of Decision; 

USCG = U.S. Coast Guard.
Tables-48 Tables

Table 3.4-7. Summary of Commercial Vessel Port Visits for Vessels >1,000 Gross Tons to Area of Interest Ports in 2012 (Modified from: 

USDOT, MARAD, 2015b)

Port State Tankers Containers LNG/PNG Roll On-Roll Off Bulk General Cargo Total Calls

Houston TX 5,555 1,008 575 223 887 1,040 9,288

South Louisiana LA 957 1 39 1 1,203 94 2,295

Sabine-Neches Waterway TX 1,642 0 80 57 301 152 2,232

New Orleans LA 409 438 21 17 883 334 2,102

Mobile AL 162 252 0 89 430 318 1,251

Texas City TX 1,045 1 0 0 27 4 1,077

Corpus Christi TX 750 0 34 4 139 85 1,012

Galveston Lightering Area TX 979 0 0 0 0 0 979

Tampa FL 331 55 86 26 271 136 905

Greater Baton Rouge LA 586 0 28 0 161 64 839

Lake Charles LA 578 0 20 0 112 102 812

Galveston TX 341 1 8 168 123 165 806

Freeport TX 444 106 49 3 13 62 677

Pascagoula MS 447 0 31 20 80 59 637

Louisiana Offshore Oil Port LA 304 0 0 0 0 0 304

Point Comfort TX 142 0 40 0 106 4 292

Ingleside TX 84 0 82 0 108 9 283

Southwest Pass Lightering Area LA 281 0 0 0 0 0 281

Gulfport MS 0 195 0 0 11 2 208

Port Manatee FL 15 1 1 0 61 115 193

Brownsville TX 72 0 0 1 88 28 189

South Sabine Point Lightering Area TX 160 0 0 0 0 0 160

Pensacola FL 2 0 0 0 4 24 30

Panama City FL 1 0 0 0 5 1 7

Total 15,287 2,058 1,094 609 5,013 2,798 26,859

FL = Florida; LA = Louisiana; LNG = liquefied natural gas; MARAD = Maritime Administration; MS = Mississippi; PNG = pressurized natural gas; 

TX = Texas.
Gulf of Mexico G&G Activities Programmatic EIS Tables-49

Table 3.4-8. Vessel Trips in the Area of Interest in 2012 Recorded by Vessels Equipped with Automatic Identifications Systems (From: Marine 

Cadastre, 2015)

Category Vessel Length (m)

No Data 5-19 20-29 30-59 60-170* 171-300 Total

No Vessel Type Reported/Not Available 47,717 1,899 2,066 2,456 1,574 1,351 57,063

Reserved for Future Use 727 116 343 1,630 883 129 3,828

Reserved, for Regional Use -- -- -- 8 -- 6 14

Wing in Ground 331 37 149 601 1,961 116 3,195

Other Types of Ship 2,416 2,300 3,411 7,237 4,408 967 20,739

Fishing 718 555 927 749 129 -- 3,078

Towing 5,125 10,464 21,988 9,395 1,609 2,562 51,143

Towing and Length of the Tow Exceeds 200 m or Breadth Exceeds 25 m 454 625 1,782 2,935 436 23 6,255

Engaged in Dredging or Underwater Operations 612 93 26 944 1,365 6 3,046

Engaged in Diving Operations 101 56 -- 548 513 -- 1,218

Engaged in Military Operations 677 545 83 1,319 480 182 3,286

Sailing 114 81 51 479 7 2 734

Pleasure Craft 374 1,066 953 3,088 376 -- 5,857

High-Speed Craft 56 79 36 564 85 5 825

Pilot Vessel 1,065 2,547 389 435 16 39 4,491

Search and Rescue Vessels 138 398 56 40 18 -- 650

Tugs 2,884 7,153 15,355 13,130 894 735 40,151

Port Tenders 90 64 4 2 16 -- 176

Vessels with Anti-Pollution Facilities or Equipment 133 2 -- 82 156 1 374

Law Enforcement Vessels 60 55 61 20 5 -- 201

Spare – for Assignments to Local Vessels 16 3 41 141 -- -- 201

Ships According to RR Resolution No. 18 (Mob 83)** -- -- 52 141 14 -- 207

Passenger Ships 1,642 1,019 854 7,589 1,079 2,303 14,486

Cargo Ships 1,616 787 277 6,026 17,100 33,528 59,334

Tankers 278 1,019 10 110 5,987 20,708 28,112

Total 67,344 30,963 48,914 59,669 39,111 62,663 308,664

m = meters; -- = no data.

*Range of survey vessels is 60-90 m.

**Resolution No. 18 (Mob-83) relates to the Procedure for Identifying and Announcing the Position of Ships and Aircraft of States Not Parties to an Armed 

Conflict.
Tables-50 Tables

Table 3.4-9. Cruise Ship Departures from Gulf of Mexico Ports by Year (From: USDOT, MARAD, 2015b)

Port State 2008 2009 2010 2011

Galveston TX 146 134 152 149

Mobile AL 84 76 75 60

New Orleans LA 79 101 89 136

Tampa FL 177 181 192 199

Total 407 492 508 544

AL = Alabama; FL = Florida; LA = Louisiana; TX = Texas. 
Gulf of Mexico G&G Activities Programmatic EIS Tables-51

Table 4.1-1. Types of Geological and Geophysical Activities by Survey Type and Associated Impact-Producing Factors Associated with Each 

Survey Type as Described in Appendix F

Survey Type

Reference Section in Appendix FAirgun and Other Active Acoustic SourcesVessel and Equipment NoiseVessel TrafficAircraft Traffic and NoiseStand-Off DistancesVessel DischargesTrash and DebrisSeafloor DisturbanceDrilling DischargesEntanglementAccidents

Deep-Penetration Seismic Surveys

2D Seismic Surveys 1.1.1 + + + + + + + - - - +

3D Seismic Surveys 1.1.2 + + + + + + + - - - +

Ocean Bottom 2D and 3D Seismic Surveys (Cables and Nodes) 1.1.3 + + + + + + + + - + +

Wide Azimuth and Related Multi-Vessel Surveys 1.1.4 + + + + + + + - - - +

Borehole Seismic Surveys (2D and 3D VSP Surveys) 1.1.5 + + + + + + + - - - +

Vertical Cable Surveys 1.1.6 + + + + + + + + - - +

4D Time-Lapse Surveys 1.1.7 + + + + + + + - - - +

Airgun High-Resolution Geophysical Surveys

High-Resolution Seismic Surveys 1.2 + + + - + + + - - - +

Non-Airgun Acoustic High-Resolution Geophysical Surveys

Subbottom Profiling Surveys 1.3.1 + + + - - + + - - - +

Side-Scan Sonars 1.3.2 + + + - - + + - - - +

Single and Multibeam Echosounders 1.3.3 + + + - - + + - - - +

Non-Acoustic Marine Geophysical Surveys

Marine Geophysical (Gravity, Magnetic, MT, CSEM) 1.4.1-1.4.4 - - + - - + + + - - +

Airborne Remote Surveys

Airborne Gravity Surveys 1.5.1 - - - + - - - - - - -

Airborne Magnetic Surveys 1.5.2 - - - + - - - - - - -

Geological and Geotechnical Surveys

Grab and Box Sampling 2.1 - + + - - + + + - - +
Table 4.1-1. Types of Geological and Geophysical Activities by Survey Type and Associated Impact-Producing Factors Associated with Each 

Survey Type as Described in Appendix F (continued)

Tables-52 Tables

Survey Type

Reference Section in Appendix FAirgun and Other Active Acoustic SourcesVessel and Equipment NoiseVessel TrafficAircraft Traffic and NoiseStand-Off DistancesVessel DischargesTrash and DebrisSeafloor DisturbanceDrilling DischargesEntanglementAccidents

Geologic Coring 2.2 - + + - + + + + + - +

COST and Shallow Test Wells 2.3 - + + - + + + + + - +

Cone Penetrometer Tests 2.4 - - + - - + + + - - +

Other Surveys and Equipment

Pingers, Transponders, ROVs, AUVs, Buoys, Anchors, Sensors 4.1-4.4 + - + - - - + + - - +

AUV = autonomous underwater vehicle; COST = continental offshore stratigraphic test; CSEM = controlled source electromagnetic; 

FAZ = full azimuth; MAZ = multi-azimuth; MT = magnetotelluric; RAZ = rich azimuth; ROV = remotely operated vehicle; VSP = vertical seismic 

profile; WAZ = wide azimuth (survey).

Key: + indicates a potential impact; - indicates no impact expected.
Gulf of Mexico G&G Activities Programmatic EIS Tables-53

Table 4.1-2. Preliminary Screening of Potential Impacts (Leopold Matrix)

Resource

Active Acoustic Sound SourcesVessel and Equipment NoiseVessel TrafficAircraft Traffic and NoiseStand-Off DistancesVessel DischargesTrash and DebrisSeafloor DisturbanceDrilling DischargesEntanglementAccidental Fuel Spill

Marine Mammals + + + + - - + - - + +

Sea Turtles + + + + - - + - - + +

Fisheries Resources and Essential Fish Habitat + + - - - - + + + + +

Benthic Communities + - - - - - + + + - +

Marine and Coastal Birds + + + + - - + - - - +

Marine Protected Areas + - - - - - + + + - +

Sargassum Communities - - + - - + + - - - +

Commercial Fisheries + - + - + - - + - + +

Recreational Fisheries + - + - + - - - - - +

Archaeological Resources - - - - - - - + + + +

Other Marine Uses - - + + + - - + - +

Human Resources, Land Use, and Economics1 - - - - - - - - - - -

Recreational Resources and Tourism - - - - - - - - - - -

Air Quality - - + + - - - - - - -

Water Quality - - - - - + + - + - +

Geography and Geology - - - - - - - + - - -

Physical Oceanography - - - - - - - - - - -

Coastal Barrier Island Beaches, Seagrass, and Wetlands - - - - - - - - - - -

G&G = geophysical and geological. 

Shading = resources were eliminated from detailed analysis due to limited anticipated impacts associated with G&G activities.

Key: + indicates a potential impact; - indicates no impact expected.

1 The impact-producing factors do not apply to this resource; however, resource subcomponents have potential impacts from some alternatives.
Tables-54 Tables

Table 4.1-3. Length and Area of Oiling of State and Federal Lands along the Northern Gulf Coast Caused by the Deepwater Horizon Oil 

Spill (From: Deepwater Horizon Natural Resource Damage Assessment Trustees, 2015, 2016) (The Federal lands include 

only USDOI sites.)

State State Lands Federal Lands (USDOI only)

Kilometers (miles) Hectares (acres) Kilometers (miles) Hectares (acres)

Texas 43 (27) 341 (842) 13 (8) 80 (197)

Louisiana 250 (156) 1,363 (3,368) 43 (27) 256 (632)

Mississippi 102 (64) 448 (1,124) 93 (57) 546 (1,334)

Alabama 116 (72) 526 (1,299) 20 (12) 99 (244)

Florida 155 (96) 737 (1,820) 114 (71) 692 (1,710)

USDOI = United States Department of the Interior.
Gulf of Mexico G&G Activities Programmatic EIS Tables-55

Table 4.2-1. Marine Mammals Potentially Occurring in the Area of Interest (Sources: Davis and Fargion, 1996; Jefferson et al., 2008; Roberts 

et al., 2016; Southall et al. 2007; Waring et al., 2013, 2014, 2015, 2016; Würsig et al., 2000) 

Species MMPA Stock1 Distribution2 Abundance 

(SAR /CetMap)3

Occurrence 

in AOI4

Habitat in 

AOI5

Auditory 

Range2

Functional 

Hearing 

Group6

Status7

(ESA/ 

MMPA 

Stock)

ORDER CETACEA

Suborder Mysticeti (Baleen Whales)

Bryde’s Whale 

(Balaenoptera edeni) Gulf of Mexico

Worldwide in tropical 

and subtropical waters 

of the world in coastal 

and pelagic waters, 

and often in shelf 

break waters or near 

topographic features.

33 44 Uncommon

Shelf Edge 

and Upper 

Slope within 

De Soto 

Canyon or 

Florida 

Escarpment

<60 to 

900 Hz L C S 

Suborder Odontoceti (Toothed Whales, Dolphins, and Porpoises)

Family Delphinidae

Pygmy Killer Whale 

(Feresa attenuata) Gulf of Mexico

Worldwide in tropical 

to subtropical oceanic 

waters.

152 2,126 Uncommon Oceanic 45 to 

117 kHz M -- --

Short-Finned Pilot Whale

(Globicephala 

macrorhynchus) 

Gulf of Mexico

Worldwide in tropical 

to subtropical waters, 

generally on the 

continental shelf break 

and in deep oceanic 

waters.

2,415 1,981 Common Oceanic 280 Hz to 

100 kHz M -- --

Risso’s Dolphin

(Grampus griseus) Gulf of Mexico

Worldwide in tropical 

to warm temperate 

waters.

2,442 3,137 Common Oceanic 400 Hz to 

65 kHz M -- --

Fraser’s Dolphin

(Lagenodelphis hosei) Gulf of Mexico

Worldwide in warm 

temperate, subtropical, 

and tropical pelagic 

waters.

-- 1,665 Uncommon Oceanic

6.6 kHz 

to 

<40 kHz

M -- --
Table 4.2-1. Marine Mammals Potentially Occurring in the Area of Interest (continued) 

Tables-56 Tables

Species MMPA Stock1 Distribution2 Abundance 

(SAR/CetMap)3

Occurrence 

in AOI4

Habitat in 

AOI5

Auditory 

Range2

Functional

Hearing 

Group6

Status7

(ESA/ 

MMPA 

Stock)

Killer Whale 

(Orcinus orca) Gulf of Mexico

Mostly in polar waters 

but can be found in 

temperate waters. 

Can be found in lower 

densities in tropical, 

subtropical, and 

offshore waters.

28 185 Uncommon Oceanic 80 Hz to 

85 kHz M -- --

Melon-Headed Whale 

(Peponocephala electra) Gulf of Mexico Worldwide in tropical 

and subtropical waters. 2,235 6,733 Common Oceanic 8 to 40 kHz M -- --

False Killer Whale 

(Pseudorca crassidens) Gulf of Mexico

Worldwide in warm 

temperate and tropical 

oceans in relatively 

deep offshore waters.

-- 3,204 Uncommon Shelf-Oceanic 4 to 

130 kHz M -- --

Pantropical Spotted 

Dolphin 

(Stenella a. attenuata) 

Gulf of Mexico Offshore tropical 

waters. 50,880 84,014 Common Oceanic 3.1 to 

140 kHz M -- --

Clymene Dolphin 

(Stenella clymene) Gulf of Mexico

Deep tropical, 

subtropical, and warm 

temperate waters.

129 11,000 Common Oceanic 0.1 to 

160 kHz M -- --

Striped Dolphin 

(Stenella coeruleoalba) Gulf of Mexico Tropical to cool 

temperate waters. 1,849 4,914 Common Oceanic 0.1 to 160 kHz M -- --

Atlantic Spotted Dolphin 

(Stenella frontalis) Gulf of Mexico Tropical to warm 

temperate waters. -- 47,488 Common Shelf-Shelf Edge

0.1 to 

160 kHz M -- --

Spinner Dolphin 

(Stenella l. longirostris) Gulf of Mexico Tropical to temperate 

oceanic waters. 11,441 13,485 Common Oceanic 0.1 to 160 kHz M -- --

Rough-Toothed Dolphin 

(Steno bredanensis) Gulf of Mexico Deep tropical and 

subtropical waters. 624 4,853 Common Shelf EdgeOceanic

0.1 to 

200 kHz M -- --

Common Bottlenose 

Dolphin

(Tursiops t. truncatus) 

Northern Gulf 

of Mexico, 

Oceanic

Worldwide in 

temperate and tropical 

waters.

5,806 138,602 Common Oceanic 0.05 to 

150 kHz M -- --
Table 4.2-1. Marine Mammals Potentially Occurring in the Area of Interest (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-57

Species MMPA Stock1 Distribution2 Abundance 

(SAR/CetMap)3

Occurrence 

in AOI4

Habitat in 

AOI5

Auditory 

Range2

Functional

Hearing 

Group6

Status7

(ESA/ 

MMPA 

Stock)

Northern Gulf 

of Mexico, 

Continental 

Shelf

Worldwide in 

temperate and tropical 

waters.

51,192 138,602 Common Shelf and 

Shelf Edge

0.05 to 

150 kHz M -- --

Gulf of Mexico, 

Eastern 

Coastal

Worldwide in 

temperate and tropical 

waters.

12,388 138,602 Common Coastal and 

Inner Shelf

0.05 to 

150 kHz M -- --

Gulf of Mexico, 

Northern 

Coastal

Worldwide in 

temperate and tropical 

waters.

7,185 138,602 Common Coastal and 

Inner Shelf

0.05 to 

150 kHz M -- S 

Gulf of Mexico, 

Western 

Coastal

Worldwide in 

temperate and tropical 

waters.

20,161 138,602 Common Coastal and 

Inner Shelf

0.05 to 

150 kHz M -- S 

Northern Gulf 

of Mexico; 

Bay, Sound, 

and Estuary 

Stock Block 

(32 stocks)

Worldwide in 

temperate and tropical 

waters.

Refer to 

Table 

4.2-2

138,602 Common 

(localized) Coastal 0.05 to 

150 kHz M -- S 
Table 4.2-1. Marine Mammals Potentially Occurring in the Area of Interest (continued) 

Tables-58 Tables

Species MMPA Stock1 Distribution2 Abundance 

(SAR/CetMap)3

Occurrence 

in AOI4

Habitat in 

AOI5

Auditory 

Range2

Functional 

Hearing 

Group6

Status7

(ESA/ 

MMPA 

Stock)

Family Physeteridae

Sperm Whale 

(Physeter microcephalus) Gulf of Mexico Worldwide in polar to 

tropical waters 763 2,128 Common Oceanic 2.5 to 60 kHz M E S 

Family Kogiidae

Pygmy Sperm Whale 

(Kogia breviceps) Gulf of Mexico

Worldwide in 

temperate to tropical 

oceanic waters. 1868 2,2348

Uncommon Oceanic 60 to 

200 kHz H -- --

Dwarf Sperm Whale 

(Kogia sima) Gulf of Mexico

Worldwide in 

temperate to tropical 

oceanic waters.

Uncommon Oceanic 60 to 

200 kHz H -- --

Family Ziphiidae

Blainville’s Beaked Whale 

(Mesoplodon densirostris) Gulf of Mexico

Worldwide in offshore 

temperate and tropical 

waters. 1498 2,9108

Rare Oceanic <1 to 

48 kHz M -- --

Gervais’ Beaked Whale 

(Mesoplodon europaeus) Gulf of Mexico

Worldwide in deep 

offshore temperate 

and tropical waters.

Uncommon Oceanic 30 to 

48 kHz M -- --

Cuvier’s Beaked Whale 

(Ziphius cavirostris) Gulf of Mexico

Deep offshore in 

subtropical and 

temperate waters.

74 2,910 Rare Oceanic 300 Hz to 

135 kHz M -- --

ORDER SIRENIA

West Indian Manatee 

(Florida subspecies)

(Trichechus manatus 

latirostris)

Florida

Warm waters 

throughout the 

southeastern United 

States.

3,3339 -- Common Shelf-Coastal 0.6 to 

12 kHz *

10 E S 

AOI = Area of Interest; CetMap = Cetacean Density and Distribution Mapping Working Group; ESA = Endangered Species Act; Hz = hertz; 

kHz = kilohertz; MMPA = Marine Mammal Protection Act; SAR = stock assessment report

-- = no data.

1

 From Waring et al., 2016. 

2

 From Appendix E, Sections 2.1-2.3. 3 SAR – Best population estimate (within associated stock). “NBest” from Table 1 of the Waring et al. (2016) SAR. CetMap abundance derived 

from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts et al., 2016).
Table 4.2-1. Marine Mammals Potentially Occurring in the Area of Interest (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-59

4 Occurrence in the Gulf of Mexico from Würsig et al. (2000). Categories include the following:

Common – abundant wherever it occurs in the region;

Uncommon – may or may not be widely distributed but does not occur in large numbers; and

Rare – present in such small numbers throughout the region that it is seldom seen;

5 From Waring et al., 2013, 2015, 2016. 6 Functional marine mammal hearing groups and specific auditory ranges (modified from Southall et al., 2007).

L = Low-Frequency Cetacean (7 Hz to 25 kHz).

M = Mid-Frequency Cetacean (150 Hz to 160 kHz).

H = High-Frequency Cetacean (200 Hz to 180 kHz). 

7 ESA Stock, C = candidate and E = endangered; MMPA Stock, S = strategic stock 8 Some congeners, such as dwarf and pygmy sperm whales, and Blainville’s and Gervais’ beaked whales are difficult to differentiate at sea, and 

sightings of either species are usually categorized as Kogia spp, and Mesoplodon spp., respectively. Therefore, the minimum population 

estimate for dwarf and pygmy sperm whales, and Blainville’s and Gervais’ beaked whales are combined (Waring et al., 2013).

9 State of Florida, Fish and Wildlife Conservation Commission (FWC), Fish and Wildlife Research Institute, 2015.

10 Manatee hearing is not addressed by Southall et al. (2007). Based on review of marine mammal hearing capabilities, manatee hearing is 

generally similar to that of the Southall et al. (2007) range for phocid pinnipeds in water (except at the lowest frequencies) (75 Hz-75 kHz).
Tables-60 Tables

Table 4.2-2. Stocks of Common Bottlenose Dolphins within the Area of Interest (From: Waring et al., 

2016) 

Stock

Bay, Sound, and 

Estuary Stock 

Block (refer to

Figure 4.2-4)

ESA/MMPA/ 

Stock Status1 Occurrence2

Best 

Population 

Estimate

Northern Gulf of Mexico Oceanic N/A - Common 5,806

Northern Gulf of Mexico Continental Shelf N/A - Common 17,777

Gulf of Mexico Eastern Coastal N/A - Common 7,702

Gulf of Mexico Northern Coastal N/A -/S Common 2,473

Gulf of Mexico Western Coastal N/A -/S Common 3,499

Bay, Sound, and Estuary Stocks

Laguna Madre B51 -/S Common (local) 80

Nueces Bay, Corpus Christi Bay B52 -/S Common (local) 58

Copano Bay, Aransas Bay, San Antonio Bay, 

Redfish Bay, Espiritu Santo Bay B50 -/S Common (local) 55

Matagorda Bay, Tres Palacios Bay, Lavaca Bay B54 -/S Common (local) 61

West Bay B55 -/S Common (local) 32

Galveston Bay, East Bay, Trinity Bay B56 -/S Common (local) 152

Sabine Lake B57 -/S Common (local) 0

Calcasieu Lake B58 -/S Common (local) 0

Vermilion Bay, West Cote Blanche Bay, 

Atchafalaya Bay B59 -/S Common (local) 0 

Terrebonne Bay, Timbalier Bay B60 -/S Common (local) 100

Barataria Bay B61 -/S Common (local) 138

Mississippi River Delta B30 -/S Common (local) 332

Mississippi Sound, Lake Borgne, Bay Boudreau B02-05, 29, 31 -/S Common (local) 901

Mobile Bay, Bon Secour Bay B06 -/S Common (local) 122

Perdido Bay B07 -/S Common (local) 0

Pensacola Bay, East Bay B08 -/S Common (local) 33

Choctawhatchee Bay B09 -/S Common (local) 179

St. Andrew Bay B10 -/S Common (local) 124

St. Joseph Bay B11 -/S Common (local) 152

St. Vincent Sound, Apalachicola Bay, 

St. George Sound B12-13 -/S Common (local) 439

Apalachee Bay B14-15 -/S Common (local) 491

Waccasassa Bay, Withlacoochee Bay, 

Crystal Bay B16 -/S Common (local) 100

St. Joseph Sound, Clearwater Harbor B17 -/S Common (local) 37

Tampa Bay B32-34 -/S Common (local) 559

Sarasota Bay, Little Sarasota Bay B20, 35 -/S Common (local) 160

Pine Island Sound, Charlotte Harbor, 

Gasparilla Sound, Lemon Bay B21-23 -/S Common (local) 826

Caloosahatchee River B36 -/S Common (local) 0

Estero Bay B24 -/S Common (local) 104

Chokoloskee Bay, Ten Thousand Islands, 

Gullivan Bay B25 -/S Common (local) 208

Whitewater Bay B27 -/S Common (local) 242

Florida Keys (Bahia Honda to Key West) B28 -/S Common (local) 29 1 E = endangered; ESA = Endangered Species Act; MMPA = Marine Mammal Protection Act; S = strategic stock. 2 Population status in the Gulf of Mexico from Würsig et al. (2000). Categories include the following: Common – abundant 

wherever it occurs in the region; Uncommon – may or may not be widely distributed but does not occur in large numbers; 

Rare – present in such small numbers throughout the region that it is seldom seen; Extralimital – known on the basis of 

only a few records that probably resulted from unusual wanderings of animals into the region.
Gulf of Mexico G&G Activities Programmatic EIS Tables-61

Table 4.2-3. Generalized Marine Mammal Hearing Groups, Associated Auditory Bandwidths, and Marine 

Mammal Species Present in the Area of Interest (Modified from: Southall et al., 2007 per 

NMFS’ 2016 Technical Guidance) 

Generalized Hearing 

Group

Estimated 

Auditory Bandwidth

Marine Mammal Species Present 

in the Area of Interest

Low-frequency cetaceans 7 Hz to 35 kHz Bryde’s whale

Mid-frequency cetaceans 150 Hz to 160 kHz

Sperm whale; beaked whales; Stenella dolphins; 

common bottlenose dolphin; killer whale; pygmy 

killer whale; false killer whale; Risso’s dolphin; 

long-finned pilot whales; melon headed whale; 

Fraser’s dolphin; rough-toothed dolphin

High-frequency cetaceans 275 Hz to 160 kHz Pygmy and dwarf sperm whales

Hz = hertz; kHz = kilohertz.

Table 4.2-4. Dual Injury Criteria for Marine Mammals Exposed to Impulsive Noise Over a 24-Hour Period

(From: Southall et al., 2007; USDOC, NMFS, 2016b) 

Marine Mammal 

Hearing Group

TTS Onset PTS Onset

Southall et al. 

(2007)

USDOC, NOAA 

(2016)

Southall et al. 

(2007)

USDOC, NOAA 

(2016)

SPLpeak1 SELcum2 SPLpeak1 SELcum2 SPLpeak1 SELcum2 SPLpeak1 SELcum2

Low-frequency cetaceans 224 183 213 168 230 198 230 183

Mid-frequency cetaceans 224 183 224 170 230 198 230 185

High-frequency cetaceans 224 183 196 140 230 198 202 155

Manatees (from phocid 

Pinniped criteria [under 

water])3

212 171 212 170 218 186 235 185

NOAA = National Oceanic and Atmospheric Administration; PTS = permanent threshold shift; 

SELcum = cumulative sound exposure level; SPLpeak = peak sound pressure level; TTS = temporary threshold 

shift; USDOC = United States Department of Commerce. 1 Measured in dB re 1 μPa. 2 Measured in dB re 1 μPa2

•s. 3 As discussed in Section 3.3 of Appendix H, data suggest that manatees have hearing capabilities similar to 

phocid seals, except perhaps at the lowest frequencies, with functional hearing between approximately 

250 hertz and 80 kilohertz. Based on these data, the extrapolation of dual injury criteria for some pinnipeds 

(phocid seals) exposed to impulsive noise to manatees, where information is lacking, would seem reasonable 

and so are used here.
Tables-62 Tables

Table 4.2-5. Existing and Proposed Injury and Behavior Exposure Criteria for Cetaceans and Manatees 

Exposed to Pulsed Sounds

Group

Level A (Injury) Level B (Behavior)

(Federal Register, 2000c) 

SPLrms1 Southall et al. (2007) SEL2 (Federal Register, 2000c)SPLrms1

Southall et al.

(2007) 

Single Pulse, 

SPLrms1

Cetaceans 180 198 160 230

Manatees (based on 

Pinniped criteria)3 190 186 160 218

FR = Federal Register; NMFS = National Marine Fisheries Service; SEL = sound exposure level; SPLrms = root mean 

square sound pressure level; USDOC = United States Department of Commerce. 

Note: Current regulatory thresholds are shaded.

1 Measured in dB re 1 μPa. 2 Measured in dB re 1 μPa2

•s. 3 As discussed in Section 3.3 of Appendix H, data suggest that manatees have hearing capabilities similar to 

phocid seals, except perhaps at the lowest frequencies, with functional hearing between approximately 250 hertz 

and 80 kilohertz. Based on these data, the extrapolation of behavior and injury exposure criteria for pinnipeds to 

manatees, where information is lacking, would seem reasonable and so are used here.
Gulf of Mexico G&G Activities Programmatic EIS Tables-63

Table 4.2-6. Density Ratios for Each of the Modeling Zones and Seasonal Restrictions/Closure Areas1

Species Name

Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 7

EPA 

Closure 

Density 

Ratio

Coastal 

Closure

Density 

Ratio

Combined 

EPA and 

Coastal 

Closures

Coastal 

Closure 

Density 

Ratio

Coastal 

Closure

Density 

Ratio

EPA 

Closure 

Density 

Ratio

Dry Tortugas 

Closure 

Density Ratio

Dry Tortugas 

and EPA 

Closure 

Density Ratio

CPA 

Closure 

Density 

Ratio

CPA 

Closure 

Density 

Ratio

Atlantic spotted dolphin 1.024 1.093 1.119 1.189 1.098 0.988 1.001 1.065 1.304 1.000

Beaked whales 

(Cuvier/Blainville/Gervais) 0.585 1.103 0.645 1.222 1.000 1.234 0.652 0.827 0.982 0.974

Common bottlenose 

dolphin 1.051 0.932 0.979 0.919 0.944 0.974 0.868 0.803 0.892 0.982

Bryde's whale 0.442 1.106 0.489 1.191 0.937 0.584 1.170 0.625 1.075 0.953

Clymene dolphin 0.258 1.105 0.285 1.190 0.800 1.191 1.126 1.429 1.094 0.989

False killer whale 0.504 1.106 0.557 1.163 1.059 0.994 0.999 0.978 0.990 1.000

Fraser’s dolphin 0.504 1.106 0.557 1.163 1.059 0.994 0.999 0.978 0.990 1.000

Killer whale 0.753 1.094 0.824 1.156 1.074 1.151 0.904 0.986 0.983 1.015

Kogia (dwarf, pygmy sperm 

whale) 0.500 1.106 0.553 1.172 0.987 1.155 0.820 0.978 0.889 0.994

Melon-headed whale 0.569 1.106 0.629 1.184 1.008 1.219 1.033 1.313 0.965 0.943

Pantropical spotted dolphin 0.532 1.106 0.588 1.172 1.005 1.206 0.782 0.979 0.886 1.002

Pygmy killer whale 0.456 1.106 0.504 1.179 1.020 1.209 0.839 1.039 0.970 0.999

Risso’s dolphin 0.396 1.106 0.438 1.166 0.977 1.153 0.681 0.756 0.809 1.022

Rough-toothed dolphin 0.962 1.019 0.980 1.026 1.008 1.068 0.948 0.992 1.019 0.991

Short-finned pilot whale 0.282 1.102 0.311 1.188 0.944 1.259 0.825 1.158 1.094 0.980

Sperm Whale 0.400 1.107 0.443 1.178 1.000 1.246 0.772 1.022 0.827 0.988

Spinner dolphin 0.587 1.106 0.649 1.190 0.799 1.159 0.965 1.199 0.157 0.848

Striped dolphin 0.191 1.106 0.211 1.162 1.047 1.160 1.250 1.542 0.715 0.954

Color Code 0.15 0.31 0.47 0.63 0.79 0.95 1.11 1.27 1.43 1.59

CPA =Central Planning Area; EPA = Eastern Planning Area. 1 The color coding ranges from a 1.59x (159%) increase in density estimates (dark orange) to a 0.15x (15%) reduction of density estimates (medium blue). Cells 

that are white are near unity (1.0x or 100%), indicating little or no change from the original density estimate.
Tables-64 Tables

Table 4.3-1. Sea Turtles Occurring in the Area of Interest

Scientific Name Common Name ESA 

Status1 Occurrence 

in the AOI Life Stage States with Nesting

Reported in the AOI Nesting References

ESA-Designated 

Critical Habitat 

in the AOI

Caretta caretta Loggerhead turtle E, T2 TX – FL All FL, AL, MS, TX

Hoggard (1991); 

Conant et al. (2009); 

Kraft (2012); 

Florida Fish and 

Wildlife Conservation 

Commission, Fish 

and Wildlife Research 

Institute (2015)

Yes

Chelonia mydas Green turtle T3 TX – FL All FL, AL (rare), 

TX (rare)

FWC (2015a); 

FWC (2015b); 

USDOI, NPS (2015); 

Sea Turtle Inc. 

(2015); 

USDOI, FWS (2015)

No

Eretmochelys imbricata Hawksbill turtle E TX – FL All FL (rare) USDOC, NMFS and 

USDOI, FWS (2013) No

Lepidochelys kempii Kemp’s ridley 

turtle E TX – FL Juveniles 

and adults FL, AL (rare), TX

USDOI, FWS

(2008b); USDOC, 

NMFS et al. (2011)

No

Dermochelys coriacea Leatherback turtle E TX – FL All FL FWC (2015c) No

AL = Alabama; AOI = Area of Interest; ESA = Endangered Species Act; FL = Florida; FWC = Florida Fish and Wildlife Conservation Commission; FWS = Fish 

and Wildlife Service; MS = Mississippi; NMFS = National Marine Fisheries Service; NPS = National Park Service; TX = Texas; USDOC = United States 

Department of Commerce; USDOI = United States Department of the Interior. 1 Endangered Species Act Status: E = endangered; T = threatened. 2 Nine distinct population segments (DPSs) of the loggerhead turtle are currently listed as endangered and threatened. Loggerhead turtles occurring in the Area 

of Interest are part of the Northwest Atlantic Ocean DPS, which is listed under the ESA as threatened (Federal Register, 2011b). Critical habitat was 

established for the Northwest Atlantic Ocean DPS in 2014; in the Area of Interest, loggerhead critical habitat for the Northwest Atlantic Ocean DPS includes 

nearshore reproductive (in State waters) and Sargassum habitats (Federal Register, 2014b). 3 On April 6, 2016, NMFS published a final rule to list 11 distinct population segments (DPSs) of the green turtle and to revise current listings under the ESA 

(Federal Register, 2016d). The North Atlantic DPS, which includes green turtles found in the Gulf of Mexico, is listed as threatened. 
Gulf of Mexico G&G Activities Programmatic EIS Tables-65

Table 4.4-1. Hard Bottom Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (Modified from: GMFMC, 

2004)

Family Name Species Name Eggs and Larvae Juvenile Adult Spawning

Triggerfishes 

(Balistidae) 

Gray triggerfish 

(Balistes 

capriscus) 

Pelagic, occur in 

upper water column, 

associated with 

Sargassum and 

flotsam

Associated with 

Sargassum, flotsam, or 

found in mangrove 

estuaries

Offshore in water depths 

greater than 10 m (33 ft); 

associated with natural 

and artificial reefs

Spawn around natural and 

artificial reefs in water 

depths greater than 10 m

(33 ft); late spring and 

summer

Jacks 

(Carangidae) 

Greater 

amberjack 

(Seriola dumerili) 

Pelagic, associated 

with floating plants 

and debris

Pelagic, associated 

with floating plants and 

debris

Pelagic and epibenthic, 

occurring over reefs, 

wrecks, and around 

buoys; to water depths 

of 400 m (1,312 ft)

Little information; spawn in 

the GOM from May to July

Lesser amberjack 

(Seriola fasciata) 

Pelagic, associated

with floating plants 

and debris

Occur offshore in late 

summer and fall in the 

GOM. Associated with 

Sargassum and flotsam

Offshore year round in 

the GOM; associated 

with oil and gas 

platforms and irregular 

bottom features

Spawn offshore September 

to December and February 

to March; likely near oil and 

gas platforms and irregular 

bottom features

Almaco jack 

(Seriola rivoliana) Unknown

Associated with 

Sargassum in open 

waters and off barrier 

islands

Offshore, associated 

with oil and gas 

platforms in the GOM

Spawning thought to occur 

from spring through fall

Banded 

rudderfish 

(Seriola zonata) 

Pelagic, associated 

with floating plants 

and debris

Offshore, associate 

with jellyfish and 

floating plants

Pelagic or epibenthic, 

coastal waters over 

continental shelf

Spawn offshore in the 

eastern GOM, Yucatan 

Channel, and Straits of 

Florida

Wrasses 

(Labridae) 

Hogfish 

(Lachnolaimus 

maximus) 

N/A Shallow seagrass beds 

of Florida bay

Moderate- to high-relief 

hard bottom structure in 

shelf waters, coral reefs 

and rocky flats

N/A
Table 4.4-1. Hard Bottom Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (continued) 

Tables-66 Tables

Family Name Species Name Eggs and Larvae Juvenile Adult Spawning

Snappers 

(Lutjanidae) 

Queen snapper 

(Etelis oculatus) Pelagic, offshore N/A

Deepwater species in 

the southern GOM; 

associate with rocky 

bottoms and ledges 

between 135- and 

450-m (443- and 

1,476-ft) water depth

N/A

Mutton snapper 

(Lutjanus analis) 

Shallow continental 

shelf waters

Shallow seagrass beds in 

tidal creeks and bights 

surrounded by 

mangroves; protected 

bays

Offshore reef areas, 

deep barrier reefs

Spawn on steep 

drop offs near reef 

areas

Schoolmaster 

(Lutjanus apodus) Pelagic

Shallow and offshore 

habitats, seagrass beds, 

mangrove habitats, 

congregate around jetties, 

inshore and offshore rocky 

and coral reefs

Coastal waters out to 

90-m (295-ft) water 

depth; occur over rock, 

vegetated sand, inshore 

and offshore reefs, and 

mud

Offshore reefs

Blackfin snapper 

(Lutjanus 

buccanella) 

Present year-round 

in shelf edge waters 

over spawning areas

Shallow hard bottom 

areas from 12- to 40-m 

(39- to 131-ft) water depth

Throughout GOM; shelf 

edge habitats from 

40- to 300-m (131- to 

984-ft) water depth

Year round with 

spring and fall 

peaks, presumably 

near shelf edge 

habitats

Red snapper 

(Lutjanus 

campechanus) 

Offshore in summer 

and fall in shelf 

waters from 17- to

183-m (56- to 600-ft) 

water depth

Associated with structure, 

also abundant over sand 

and mud bottom; from 

20- to 46-m (66- to 151-ft) 

water depth

Throughout GOM; occur 

in submarine gullies and 

depressions, over coral 

reefs, rock outcroppings, 

and gravel bottom; 7- to

146-m (23- to 479-ft) 

water depth

Offshore from May 

to October in 18- to

37-m (59- to 121-ft) 

water depth over 

fine sand bottom 

away from reefs

Cubera snapper 

(Lutjanus 

cyanopterus) 

Presumed in June 

and July as a result 

of spawning 

aggregations, open 

water near reefs and 

wrecks

Streams, canals, seagrass 

beds, mangrove areas, 

and lagoons

Most common off 

southwestern Florida; 

shallow and deep reefs 

and wrecks; mangroves; 

up to 85-m (279-ft) water 

depth

Spawn in June and 

July near wrecks 

and deep reefs in 

67- to 85-m (220- to 

279-ft) water depth
Table 4.4-1. Hard Bottom Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-67

Family Name Species Name Eggs and Larvae Juvenile Adult Spawning

Snappers 

(Lutjanidae) 

(continued)

Gray snapper 

(Lutjanus griseus) 

Occur June through 

August in offshore 

shelf waters and 

near coral reefs; 

move to estuarine 

habitats and 

seagrass beds

Marine, estuarine, and 

riverine dwellers, prefer 

Thalassia sp. grass beds, 

marl bottoms, seagrass 

meadows, and mangrove 

roots

Estuaries and shelf 

waters 180-m (591-ft) 

water depth; demersal 

and mid-water dwellers; 

marine, estuarine, and 

riverine dwellers

Spawn offshore 

around reefs and 

shoals from June to 

August

Dog snapper 

(Lutjanus jocu) Pelagic

Shallow water seagrass 

beds; coastal waters, 

estuaries, or rivers; 

mangrove roots, jetties, 

and pilings

From shallow vegetated 

areas to deep reefs to 

150-m (492-ft) water 

depth; coral reefs

Spawning 

aggregations near 

reefs from 15- to

30-m (49- to 98-ft) 

water depth

Mahogany snapper 

(Lutjanus mahogoni) Pelagic N/A

Throughout GOM; 

shallow water down to 

30-m (98-ft) water depth; 

rocky bottoms and reefs

Multiple spawnings, 

spring and fall

Lane snapper 

(Lutjanus synagris) Offshore, on shelf

Mangrove and grassy 

estuarine areas; shallow 

areas with sandy and 

muddy bottoms; grass 

flats, reefs, and soft 

bottom to 20-m (60-ft) 

water depth

Offshore from 4- to

132-m (13- to 433-ft) 

water depth; occur on 

sand bottom, natural 

channels, banks, and 

artificial reefs and 

structures

Offshore from 

March through 

September

Silk snapper 

(Lutjanus vivanus) N/A Shallow water

Throughout GOM; near 

the edge of continental 

and island shelves, 

common between 

90- and 200-m (295- and 

656-ft) water depth

Throughout the 

year with peak 

spawning from July 

to August

Yellowtail snapper 

(Ocyurus chrysurus) 

Nearshore areas over 

vegetated sandy 

substrate, muddy shallow 

bays, Thalassia sp. beds 

and mangrove roots, 

shallow reef areas

Throughout shelf area of 

GOM, shallow water to 

183-m (600-ft) water 

depth; semi-pelagic 

wanderers over reef 

habitat, irregular bottom, 

coral reefs, banks, and 

shelves

February through 

October in offshore 

areas
Table 4.4-1. Hard Bottom Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (continued) 

Tables-68 Tables

Family Name Species Name Eggs and Larvae Juvenile Adult Spawning

Snappers 

(Lutjanidae) 

(continued)

Wenchman 

(Pristipomoides 

aquilonaris) 

Presumed in warmer 

months along mid to 

outer shelf water

N/A

Throughout GOM; hard 

bottom habitats of mid to 

outer shelf; 19- to 378-m 

(62- to 1,240-ft) water 

depth

Presumed warmer 

months along deep 

slopes between 

80- and 200-m 

water depth

Vermilion snapper 

(Rhomboplites 

aurorubens) 

N/A

Reefs, underwater 

structures and hard 

bottom habitats 20- to

200-m (66- to 656-ft) 

water depth

Throughout shelf area of 

the GOM, demersal, 

over reefs and rocky 

bottom from 20- to

200-m (66- to 656-ft) 

water depth

April to September 

in offshore areas

Tilefishes 

(Malacanthidae) 

Goldface tilefish 

(Caulolatilus 

chrysops)

N/A N/A N/A N/A

Blackline tilefish 

(Caulolatilus 

cyanops)

N/A N/A N/A N/A

Anchor tilefish 

(Caulolatilus 

intermedius) 

N/A N/A

Common in the northern 

and western GOM; 

irregular bottom, 

troughs, terraces, sand, 

mud and rubble, shell 

hash

N/A

Blueline tilefish 

(Caulolatilus 

microps)

Pelagic, offshore N/A

Eastern and 

southeastern GOM; 

epibenthic browsers

N/A

Golden tilefish 

(Lopholatilus 

chamaeleonticeps) 

Pelagic

Pelagic to benthic; burrow 

and occupy shafts in the 

substrate

Throughout the GOM; 

demersal from 80- to

450-m (262- to 1,476-ft) 

water depth; rough 

bottom, steep slopes; 

burrow

From March to 

November 

throughout range
Table 4.4-1. Hard Bottom Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-69

Family Name Species Name Eggs and Larvae Juvenile Adult Spawning

Groupers 

(Epinephelidae) 

Rock hind 

(Epinephelus 

adscensionis) 

Pelagic, offshore Early juveniles in shallow 

waters

Shallow hard bottom, 

coral and rock reefs, 

rock piles, oil and gas 

platforms, steep crevices 

and ledges; 2- to 100-m 

(7- to 328-ft) water depth

January to June in 

Florida middle 

grounds in 

spawning 

aggregations

Groupers 

(Epinephelidae) 

(continued)

Speckled hind 

(Epinephelus 

drummondhayi) 

Pelagic, offshore Found in shallow end of 

depth range

North and eastern GOM 

on offshore hard bottom 

habitats, rocky bottom, 

high and low profile 

bottom; 25- to 183-m 

(82- to 600-ft) water 

depth

Deeper portion of 

depth range, 

greater than 146-m 

(479-ft) depth along 

shelf edge, April to 

May, July to 

September

Yellowedge grouper 

(Hyporthodus 

flavolimbatus) 

Pelagic, offshore Inhabit burrows

Throughout deep waters 

of the GOM; high-relief 

hard bottom, rocky out 

croppings, inhabit 

burrows; 35- to 370-m 

(115- to 1,214-ft) water 

depth

Form spawning 

aggregations, 

peaks May to 

September

Red hind 

(Epinephelus 

guttatus) 

Pelagic, settle and 

develop in shallow 

inshore areas

Patch reefs, coral, and 

limestone rock

Occupy reefs, stony 

coral, holes, and 

crevices, sandy bottoms 

with coral patches; 

18- to 110-m (59- to 

361-ft) water depth

Late spring and 

summer on Florida 

Middle Grounds 

along seaward side 

of submerged 

ridges

Goliath grouper 

(Epinephelus itajara) 

Offshore, late 

summer, early fall

Bays and estuaries, 

inshore grassbeds, 

canals, mangroves, 

ledges, reefs, and holes

Shallow waters of GOM 

to 95-m (312-ft) water 

depth; inshore around 

docks, bridges, jetties, 

reef crevices, offshore 

ledges, and wrecks

June to December 

around offshore 

structures, wrecks, 

and patch reefs
Table 4.4-1. Hard Bottom Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (continued) 

Tables-70 Tables

Family Name Species Name Eggs and Larvae Juvenile Adult Spawning

Red grouper 

(Epinephelus morio) 

Pelagic as larvae, 

become benthic by 

2-mm (0.8-in) 

standard length

Inshore hard bottom 

around 50-m (164-ft) 

water depth, crevices, 

grass bets, rock 

formations, shallow reefs

Demersal throughout the 

GOM from 3- to 200-m 

(10- to 656-ft) water 

depth; rocky outcrops, 

wrecks, reefs, ledges, 

crevices and caverns of 

rock bottom, and live 

bottom

Spawn on Florida 

banks during April 

and May, do not 

aggregate, near 

low-relief habitats 

often near solution 

holes

Misty grouper 

(Hyporthodus 

mystacinus) 

N/A Shallower water than 

adults

Offshore throughout the 

GOM; hard bottom slope 

and shelf substrates, 

high-relief rocky ledges 

and pinnacles, 100- to

400-m (328- to 1,312-ft) 

water depth

April through July

Groupers 

(Epinephelidae) 

(continued)

Warsaw grouper 

(Hyporthodus 

nigritus) 

Pelagic, offshore Shallow nearshore 

habitats, bays

Throughout GOM; hard 

bottom, rocky, high 

profile, steep cliffs, rocky 

ledges, from 40- to

525-m (131- to 1,722-ft) 

water depth

Likely late summer

Snowy grouper 

(Epinephelus 

niveatus) 

Pelagic, offshore Shallow, nearshore reefs

Deep water, rocky 

bottom, offshore around 

boulders and ridges

April to July off of 

Florida keys; May 

to August west 

Florida

Nassau grouper 

(Epinephelus 

striatus)

December to 

February, 

nearshore, 0.8 to 

16 km (0.5 to 10 mi) 

from shore

Inshore seagrass beds, 

macroalgal mats, tilefish 

mounds, and small coral 

clumps

Reefs and crevice caves 

down to 100-m (328-ft) 

water depth; primarily 

along the Florida Keys’ 

reef tract

Spawning offshore 

reefs and hard

bottom outside of 

the GOM

Marbled grouper 

(Epinephelus 

inermis)

N/A N/A

Nearshore and offshore 

reefs, 3 to 213 m (10 to 

699 ft)

N/A
Table 4.4-1. Hard Bottom Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-71

Family Name Species Name Eggs and Larvae Juvenile Adult Spawning

Black grouper 

(Mycteroperca 

banaci) 

Pelagic, offshore

Shallow water reefs, rocky 

bottom, patch reefs, 

muddy bottom, mangrove 

lagoons, and estuaries

Found along eastern 

GOM, rare in western 

GOM, demersal from 

shore to 150-m (492-ft) 

water depth; wrecks, 

rocky coral reefs, 

irregular bottom, ledges

Late winter through 

spring and summer, 

aggregations 

observed in Florida 

keys at 18- to 28-m 

(59- to 92-ft) water 

depth

Yellowmouth 

grouper 

(Mycteroperca 

interstitialis) 

Pelagic, offshore Mangrove-lined lagoons

Campeche banks, west 

coast of Florida, Texas 

Flower Garden Banks, 

rocky bottoms, and coral 

reefs

Spring and summer

Gag grouper 

(Mycteroperca 

microlepis) 

Pelagic, greatest 

offshore abundance 

on west Florida shelf 

December through 

April

Move through inlets into 

coastal lagoons, high 

salinity estuaries in April 

and May, become benthic 

and settle into grass flats 

and oyster beds; later 

juveniles move to shallow 

reef habitats from 1- to

50-m (3- to 164-ft) water 

depth

Demersal; hard bottom 

substrates, offshore 

reefs and wrecks, coral 

and live bottom, 

depressions, and ledges

Aggregate in 50- to

120-m (164- to 

394-ft) water depth 

along shelf edge 

breaks from 

December to April 

on the west Florida 

shelf

Groupers 

(Epinephelidae) 

(continued)

Scamp 

(Mycteroperca 

phenax) 

Pelagic; occur in 

spring

Inshore hard bottom and 

reefs, 12- to 33-m (39- to 

108-ft) water depth

Demersal, throughout 

shelf areas of GOM, 

ledges, high relief hard 

bottom in water depth 

from 12 to 189 m (39 to 

620 ft)

Late February to 

early June in 

aggregations, shelf 

edge, often spawn 

on Oculina 

formations

Yellowfin 

(Mycteroperca 

venosa) 

N/A

Shallow seagrass beds, 

move to deeper rocky 

bottoms with age

Uncommon in the GOM, 

primarily southern GOM, 

reef ridge and high-relief 

spur and groove reefs

March to August in 

the eastern GOM

ft = feet; GOM = Gulf of Mexico; in = inches; km = kilometers; m = meters; mi = miles; mm = millimeters; N/A = not available.
Tables-72 Tables

Table 4.4-2. Coastal Migratory Pelagic Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (Modified from: 

GMFMC, 2004)

Species Name Eggs and Larvae Juvenile Adult Spawning

King mackerel 

(Scomberomorus cavalla) 

Pelagic eggs offshore over areas of 

35- to 180-m (115- to 591-ft) water 

depth, middle and outer continental 

shelf

Inshore to the 

middle shelf

Throughout the GOM, over reefs 

and coastal waters, generally in 

less than 80-m (262-ft) water depth

Over the outer 

continental shelf from 

May to October

Spanish mackerel 

(Scomberomorus 

maculatus) 

Pelagic eggs over the inner 

continental shelf at water depths 

less than 50 m (164 ft) in spring 

and summer

Estuarine and 

coastal waters

Throughout the GOM, inshore 

coastal waters, may enter 

estuaries, to water depths of 75 m

(246 ft)

Over inner 

continental shelf from 

May to September

Cobia 

(Rachycentron canadum) 

Eggs drift in the top meter of the 

water column, larvae are found in 

offshore waters

Coastal and 

offshore 

waters

Coastal and offshore waters from 

bays and inlets to the continental 

shelf; 1- to 70-m (3- to 230-ft) water 

depth

In coastal waters 

from April through 

September

ft = feet; GOM = Gulf of Mexico; m = meters.
Gulf of Mexico G&G Activities Programmatic EIS Tables-73

Table 4.4-3. Highly Migratory Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest

Species Name Eggs and Larvae Juvenile Adult Spawning/Reproduction

Albacore tuna 

(Thunnus 

alalunga) 

N/A N/A

Epipelagic, oceanic, generally 

found in surface waters, often 

associated with Sargassum

communities and debris

N/A

Bigeye tuna 

(Thunnus obesus) N/A

School near sea surface 

with other tuna species, 

associated with 

Sargassum communities 

and floating debris

N/A N/A

Bluefin tuna 

(Thunnus thynnus) Over continental shelf

Over continental shelf 

during summer, farther 

offshore in winter

Epipelagic, oceanic, generally 

found in surface waters, often 

associated with Sargassum

communities and debris

Annual spawn May to June in 

GOM

Skipjack tuna 

(Katsuwonus 

pelamis) 

N/A N/A

Epipelagic, oceanic, as deep as 

260 m (853 ft) during the day, 

associate with drifting objects, 

whales, sharks, and other tuna 

species

Opportunistic spawning 

throughout year, most spawning 

from April to May

Yellowfin tuna 

(Thunnus 

albacares) 

Limited to water 

temperature greater than 

24°C (75°F) and salinity 

greater than 33 ppt

Nearer to shore than 

adults

Epipelagic, oceanic, mix with 

skipjack and bigeye tuna 

species, occur beyond 

500-fathom isobath in the upper 

100 m (328 ft) of the water 

column

Spawning throughout year with 

peaks in the summer

Swordfish 

(Xiphias gladius) 

Present year round in the 

eastern GOM, also 

present in the western 

GOM from March to May 

and September to 

November

N/A Epipelagic to mesopelagic, 

diurnal vertical migration N/A

Blue marlin 

(Mokaira nigricans)

Some larvae present in 

the GOM N/A Epipelagic and oceanic N/A
Table 4.4-3. Highly Migratory Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (continued) 

Tables-74 Tables

Species Name Eggs and Larvae Juvenile Adult Spawning/Reproduction

White marlin 

(Tetrapturus 

albidus) 

N/A

Off west coast of Florida 

between the 200- and 

2,000-m (656- to 

6,562-ft) isobaths; off 

coast of Texas to 50-m 

(164-ft) isobath

Epipelagic and oceanic, usually 

occur above thermocline in 

deep ≥100 m [328 ft]) water 

with surface temp ≥22°C (72°F) 

and salinities of 35-37; usually 

in upper 30 m (98 ft) of the 

water column

N/A

Roundscale 

spearfish 

(Tetrapturus 

georgii) 

N/A N/A Epipelagic and oceanic N/A

Sailfish 

(Istiophorus 

platypterus) 

Larvae found in offshore 

waters from March to 

October

In all waters of the GOM 

from the 200- to 2,000-m 

(656- 6,562-ft) isobath or 

EEZ boundary

Epipelagic, coastal, and 

oceanic; usually found above 

thermocline at a temperature 

range of 21°C to 28°C (70°F to 

83°F); often move to inshore 

waters and over the shelf edge

Occurs in shallow waters 

around Florida beyond the 

100-m (328-ft) isobath, from 

April to September

Longbill spearfish 

(Tetrapturus 

pfluegeri) 

N/A N/A

Relatively rare in the GOM; 

epipelagic, oceanic species 

inhabiting waters above the 

thermocline; generally found in 

offshore waters

N/A

*Dolphinfish 

(Coryphaena 

hippurus)

Larvae abundant in 

Sargassum communities, 

prominent near the 

Mississippi River delta

Closely associated with 

Sargassum communities 

and floating debris

Oceanic pelagic; both offshore 

and coastal inshore; out to 

1,800-m (5,906-ft) water depth, 

common between 40- and

200-m (131- and 656-ft) water 

depth, closely associated with 

Sargassum communities

Multiple spawning events 

throughout year; spring and 

early fall in the GOM; offshore, 

continental shelf, and upper 

slope waters

*Wahoo 

(Acanthocybium 

solandri) 

Oceanic and shelf waters

Oceanic and shelf 

waters, associated with 

Sargassum communities 

and flotsam

Oceanic and shelf waters, 

associated with Sargassum

communities and flotsam

N/A

°C = degrees Celsius; °F = degrees Fahrenheit; EEZ = Exclusive Economic Zone; ft = feet; GOM = Gulf of Mexico; m = meters; 

N/A = not available; ppt = parts per thousand.

* Species not managed in the GOM by the U.S. Dept. of Commerce, National Marine Fisheries Service.
Gulf of Mexico G&G Activities Programmatic EIS Tables-75

Table 4.4-4. Shark Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest

Shark Group Species Name Neonates/Juvenile Adult Reproduction

Small Coastal

Angel shark (Squatina

dumeril) Shallow coastal waters Shallow coastal waters Up to 16 pup litters

Bonnethead shark 

(Sphyrna tiburo) N/A Shallow coastal waters, sandy 

and muddy bottoms

Annual reproductive 

cycle, 8-2 pup litters

Atlantic sharpnose shark 

(Rhizoprionodon 

terraenovae)

Shallow coastal waters Shallow coastal waters Late June, 4-7 pup litters

Blacknose shark 

(Carcharhinus acronotus) Shallow coastal waters Shallow coastal waters 3-6 pup litters

Finetooth shark 

(Carcharhinus isodon)

Shallow coastal waters, muddy 

bottom Shallow coastal waters Biennial reproductive cycle, 2-6 pup litters

Large Coastal

Great hammerhead shark 

(Sphyrna mokarran) Shallow coastal waters Open ocean and shallow coastal 

waters

Biennial reproductive 

cycle, 20-40 pup litters

Scalloped hammerhead 

shark (Sphyrna lewini) Shallow coastal waters Schooling, open ocean and 

shallow coastal waters

Annual reproductive 

cycle, 15-31 pup litters

White shark 

(Carcharodon carcharias) N/A N/A N/A

Nurse shark 

(Ginglymostoma cirratum) 

Shallow Thalassia beds and 

shallow coral reefs, mangrove 

islands

Littoral waters, congregates in 

shallow water

June to July in the 

shallow waters of the 

Florida Keys, 20-30 pup 

litters

Bignose shark 

(Carcharhinus altimus) N/A Deepwater species, continental 

shelf N/A

Blacktip shark 

(Carcharhinus limbatus) 

Year-round in shallow coastal 

waters, seagrass beds, and 

muddy bottoms

Shallow coastal waters and 

offshore surface waters of 

continental shelf, throughout the 

GOM

1-8 pup litters

Bull shark 

(Carcharhinus leucas)

Low salinity estuaries of the 

Gulf Coast

Shallow coastal waters and often 

fresh water

Likely biennial 

reproductive cycle

Caribbean reef shark 

(Carcharhinus perezi) N/A Shallow coastal waters, bottomdwelling, near coral reefs

Biennial reproductive 

cycle, 4-6 pup litters

Dusky shark 

(Carcharhinus obscurus)

Shallow coastal waters, inlets, 

and estuaries

Migratory, inshore and outer 

continental shelf waters 6-14 pup litters
Table 4.4-4. Shark Species and Life Stages with Essential Fish Habitat Identified within the Area of Interest (continued)

Tables-76 Tables

Shark Group Species Name Neonates/Juvenile Adult Reproduction

Large Coastal 

(Continued)

Lemon shark 

(Negaprion brevirostris)

Shallow coastal water, near 

mangrove islands

Shallow coastal waters, around 

coral reefs

Biennial reproductive 

cycle, 5-17 pup litters

Night shark 

(Carcharhinus signatus) N/A

Depths >275-366 m (902-1,201 

ft)during the day and 183 m (600 

ft) at night

N/A

Sandbar shark 

(Carcharhinus plumbeus) Shallow coastal waters Shallow coastal waters

Biennial reproductive 

cycle, March to July, 

1-14 pup litters

Silky shark 

(Carcharhinus falciformis)

Offshore and shallow coastal 

waters Offshore, epipelagic 10-14 pup litters

Spinner shark 

(Carcharhinus brevipinna) 

Shallow coastal waters, muddy 

bottom less than 5-m (16-ft) 

water depth, seagrass beds

Migratory, coastal-pelagic Biennial reproductive 

cycle, 6-12 pup litters

Tiger shark 

(Galeocerdo cuvier) N/A Shallow coastal waters and deep 

oceanic waters 35-55 pup litters

Whale shark 

(Rhincodon typus) N/A Pelagic waters N/A

Pelagic

Longfin mako shark 

(Isurus paucus) N/A Deepwater species 2-8 pup litters

Porbeagle shark 

(Lamna nasus) N/A Deepwater species N/A

Shortfin mako shark 

(Isurus oxyrinchus) N/A Oceanic waters Biennial reproductive 

cycle, 12-20 pup litters

Oceanic whitetip shark 

(Carcharhinus 

longimanus)

Likely offshore over continental 

shelf Oceanic waters Likely biennial, 2-10 pup 

litters

Bigeye thresher shark 

(Alopias superciliosus) N/A Deep water 2 pup litters

Common thresher shark 

(Alopias vulpinus) N/A Coastal and oceanic waters Birth annually from March 

to June, 4-6 pup litters

Smooth dogfish 

(Mustelus canis) N/A

Continental and insular shelves 

from shallow inshore waters to a 

maximum water depth of 579 m

(1,900 ft)

4-20 pup litters

ft = feet; GOM = Gulf of Mexico; m = meters; N/A = not available.
Gulf of Mexico G&G Activities Programmatic EIS Tables-77

Table 4.5-1. Topographic Features (Banks) of the Gulf of Mexico

Shelf-Edge Banks Mid-Shelf Banks South Texas Banks

Western 

Planning Area

Central 

Planning Area

Western 

Planning Area

Central 

Planning Area

Western 

Planning Area

Central 

Planning Area

• Appelbaum Bank

• East Flower Garden 

Bank

• MacNeil Bank

• Rankin Bank

• West Flower Garden 

Bank

• Alderdice Bank

• Bouma Bank

• Bright Bank

• Diaphus Bank

• Elvers Bank

• Ewing Bank

• Geyer Bank

• Jakkula Bank

• McGrail Bank

• Parker Bank

• Rezak Bank

• Sidner Bank

• Sweet Bank

• 29 Fathom Bank

• 32 Fathom Bank

• Claypile Lump

• Coffee Lump

• Stetson Bank

• Fishnet Bank

• Sackett Bank

• Sonnier Bank

• Aransas Bank

• Baker Bank

• Big Dunn Bar

• Blackfish Ridge

• Dream Bank

• Hospital Bank

• Mysterious Bank

• North Hospital Bank

• Small Dunn Bar

• South Baker Bank

• Southern Bank

• None
 

Tables-78 Tables

Table 4.6-1. Families of Seabirds, Waterfowl, and Shorebirds Occurring in the Area of Interest

Order Family General Ecology General Distribution/Migration

Seabirds

Charadriiformes

Laridae 

(Gulls, terns,

and phalaropes)

Primarily inhabit coastal or inshore waters. 

Conspicuous and gregarious in nature. Nest 

colonially on the ground. Most feed on small fishes 

with some foraging on insects and crabs. Terns 

typically forage by hovering above the water’s surface 

and plunge-diving head first into the water from flight. 

Gulls seldom dive and prefer open areas. Highly 

adaptable.

Found predominantly along the coast but also 

inland in both populated and open areas. Found 

in the Arctic, northern Canada, and northern U.S., 

with some species migrating south to Mexico and 

South America.

Rhyncopidae 

(Skimmers)

Primarily inhabit coastal and inshore waters. Nest 

colonially on sandy beaches. Forage for small fishes 

mainly at night, flying over shallow water with their 

elongated lower mandible below the water surface.

Year-round coastal distribution throughout the 

AOI.

Gaviiformes Gaviidae 

(Loons)

Medium to large birds that capture prey (fishes, 

crustaceans, and other aquatic organisms) by diving 

and pursuing prey underwater. Habitat includes 

tundra lakes and ponds in summer and coastal waters 

in winter. Nest on banks of ponds or lakes and winter 

on the open water.

Holarctic in the summer in freshwater areas. 

Highly migratory to more marine areas in 

northern Mexico for winter.

Pelecaniformes

Pelecanidae 

(Pelicans)

Very large, social water birds that swim buoyantly and 

feed predominantly on fishes and crustaceans in 

primarily shallow estuarine waters, occasionally up to 

40 miles (64 kilometers) from shore. Plunge bill-first 

into the water while fishing and often fly just above the 

water surface looking for prey. Nesting occurs usually 

on coastal islands, on the ground, or in small bushes 

and trees.

Found in freshwater and marine coastal waters. 

Breeding range for the brown pelican extends 

along Florida to Louisiana. The primary winter 

range for the white pelican includes Florida and 

the Gulf Coast. Breeding activities extremely 

sensitive to human activity.

Phaethontidae 

(Tropicbirds)

A mainly pelagic, highly aerial, solitary seabird found 

far offshore over and resting on warm water. Feed by 

plunge-diving. Nest in small to large colonies on 

tropical islands in rocky crevices, holes, or caves.

Distributed in tropical and subtropical waters. 

Occasionally found within the north Gulf Coast. 

Breed in Bermuda.
Table 4.6-1. Families of Seabirds, Waterfowl, and Shorebirds Occurring in the Area of Interest (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-79

Order Family General Ecology General Distribution/Migration

Pelecaniformes 

(Continued)

Phalacrocoracidae 

(Cormorants)

Large, gregarious water birds found in coastal bays, 

marine islands, and seacoasts usually within sight of 

land. Some species are found along rocky shores, 

while others are found in open water. Eat mostly 

schooling fishes captured by diving.

Migratory and dispersive. Found along 

temperate and tropical marine coasts. 

Cosmopolitan. Northern coastal 

populations migrate southward for the 

nonbreeding winter season throughout the 

Gulf of Mexico and are year-round 

residents along coastal Florida.

Sulidae 

(Boobies)

Gregarious and colonial breeders in marine 

environment. Fish by plunging from air for fishes and 

squids. Boobies land-roost. Nest in colonies on 

islands and rock stacks.

Tropical, subtropical, and temperate 

oceans. Oceanic, with some found well 

offshore while others stay close to shore. 

Occasionally found off the Gulf Coast.

Fregatidae 

(Frigatebirds)

Found in offshore and coastal waters. Feeding habits 

are pelagic and include snatching prey from the sea 

surface or beach, or in some cases by robbing other 

seabirds of their catch (kleptoparasitism).

One species (magnificent frigatebird 

[Fregatta magnificens]) occurs within the 

AOI with breeding range along Florida to 

Louisiana.

Podicipediformes Podicipedidae 

(Grebes)

Found in ponds, lakes, salt bays, and nearshore 

habitats. Feed by diving. Spend virtually all their time 

in the water and are clumsy on land.

Cosmopolitan. Migrate from inland 

breeding areas to temperate nearshore 

areas. Breed on fresh water.

Procellariiformes

Hydrobatidae 

(Storm-petrels)

Medium to large seabirds found over the open ocean 

and come to land only for nesting. Colonial breeders. 

Feed on plankton, crustaceans, and small fishes. Nest 

on sea islands.

Breed November-May in the Antarctic and 

are transequatorial migrants offshore at 

higher latitudes, Florida and Alabama.

Procellariidae 

(Shearwaters)

Highly pelagic and return to land only for breeding. 

Feed on fishes, squids, and crustaceans. Colonial 

breeders on marine islands.

Transequatorial. Most breed in the 

northern Atlantic and migrate south in 

summer as far as South America. Found 

at the sea along the Gulf Coast.

Waterfowl

Anseriformes

Anatidae 

(Aythyinae) 

(Diving ducks)

Mainly in freshwater and estuarine environments but 

species such as the greater scaup become marine 

during the winter. Breed in marshes. All dive for food

that includes aquatic vegetation, mollusks, and 

crustaceans.

Arctic, circumpolar during nesting season. 

Migrate into temperate areas in winter. 

Frequent inland waters, estuaries and 

bays, and nearshore waters. Rare to 

scarce in the Gulf Coast States.

Anatidae 

(Merginae) 

(Sea ducks)

Found in marine environment along the seacoast. 

Breed in marshes. All dive for food that includes 

mollusks and crustaceans.

Arctic, circumpolar during nesting season. 

Most migrate into subarctic and northern 

temperate areas in winter ,including along 

the Gulf Coast.
Table 4.6-1. Families of Seabirds, Waterfowl, and Shorebirds Occurring in the AOI (continued) 

Tables-80 Tables

Order Family General Ecology General Distribution/Migration

Shorebirds

Charadriiformes

Charadriidae 

(Plovers)

Wading birds found along mud flats, shores, and 

beaches that feed on small marine life, insects, and 

some vegetable matter. Nest singly or in loose 

colonies.

Arctic, circumpolar. Winter along coastal 

U.S. and Gulf of Mexico to South America, 

migrate along the coast. 

Haematopodidae 

(Oystercatchers)

Large wading birds found along coastal shores and 

tidal flats. Feed on mollusks, crabs, and marine 

worms.

Found in localized area along the Gulf 

Coast States.

Recurvirostridae 

(Avocets and stilts)

Slim wading birds found along beaches and mud flats. 

Feed on insects, crustaceans, and other aquatic 

organisms. Typically nest on open flats or areas with 

scattered tufts of grass on islands.

Breed in southwest Canada and make 

seasonal migration to southern U.S., 

including the Gulf Coast to Guatemala.

Scolopacidae 

(Sandpipers, 

curlews, godwits, 

turnstones, and 

yellowlegs)

Small- to medium-sized wading birds found along mud 

flats, tidal flats, shores, beaches, and salt marshes. 

Feed on insects, crustaceans, mollusks, and worms.

Cosmopolitan. Migrate along the coast 

from northern North America south to the 

Gulf of Mexico and as far as southern 

South America.

AOI = Area of Interest.

Data from: Peterson, 1980; Harrison, 1983, 1987; Sibley, 2000; Morrison et al., 2001; NatureServe, InfoNatura, 2013.
Gulf of Mexico G&G Activities Programmatic EIS Tables-81

Table 4.7-1. National System Marine Protected Areas Within or Partially Within the Area of Interest (From: USDOC, NOAA, MPA Centers, 2014) 

Site Government 

Level

Managing 

Agency

Primary 

Conservation Focus Status

Area 

within AOI 

(km2)

Total Area 

(km2

) 

Percentage 

within AOI

Offshores MPAs

National Marine Sanctuaries

Flower Garden Banks NMS Federal ONMS Natural Heritage Member 145.14 145.14 100

Florida Keys NMS Federal ONMS Natural Heritage Member 5,664.07 9,824.83 58

Other Federal Fishery Management Areas

De Soto Canyon Closed Area Federal NMFS Sustainable 

Production Eligible 86,854.46 86,854.46 100

East Florida Coast Closed Area Federal NMFS Sustainable 

Production Eligible 12.25 102,862.47 0 

Florida Middle Grounds HAPC Federal NMFS Natural Heritage Eligible 1,159.62 1,159.62 100

Closure of the Madison and Swanson Sites Federal NMFS Sustainable 

Production Eligible 393.33 393.33 100

McGrail Bank HAPC Federal NMFS Sustainable 

Production Eligible 48.20 48.20 100

Pelagic Sargassum Habitat Restricted Area Federal NMFS Sustainable 

Production Eligible 63.01 491,548.41 0 

Pulley Ridge HAPC Federal NMFS Sustainable 

Production Eligible 344.14 344.14 100

Reef Fish Longline and Buoy Gear Restricted 

Area Federal NMFS Sustainable Production Eligible 177,932.03 177,934.76 100

Reef Fish Stressed Area Federal NMFS Sustainable 

Production Eligible 98,554.25 98,557.81 100

Steamboat Lumps Federal NMFS Sustainable 

Production Eligible 364.57 364.57 100

Stetson Bank HAPC Federal NMFS Sustainable 

Production Eligible 6.02 6.02 100

Tortugas Marine Reserves Federal NMFS Natural Heritage Eligible 229.40 229.40 100

West and East Flower Garden Banks HAPC Federal NMFS Sustainable 

Production Eligible 220.55 220.55 100
Table 4.7-1. National System Marine Protected Areas Within or Partially Within the Area of Interest (continued) 

Tables-82 Tables

Site Government 

Level

Managing 

Agency

Primary 

Conservation Focus Status

Area 

within AOI 

(km2)

Total Area 

(km2

) 

Percentage 

within AOI

Coastal MPAs

National Park Service

Dry Tortugas National Park Federal NPS Natural Heritage Member 257.98 261.38 99

Everglades National Park Federal NPS Natural Heritage Member 775.30 6,205.68 12

Gulf Islands National Seashore Federal NPS Natural Heritage Eligible 222.28 526.60 42

Padre Island National Seashore Federal NPS Natural Heritage Member 63.96 528.78 12

National Wildlife Refuges

Anahuac NWR Federal FWS Natural Heritage Member 0.73 331.34 0

Aransas NWR Federal FWS Natural Heritage Member 21.82 471.28 5

Breton NWR Federal FWS Natural Heritage Member 30.45 30.45 100

Cedar Keys NWR Federal FWS Natural Heritage Member 3.32 3.32 100

Chassahowitzka NWR Federal FWS Natural Heritage Member 71.54 148.68 48

Crystal River NWR Federal FWS Natural Heritage Member 3.90 33.84 12

Delta NWR Federal FWS Natural Heritage Member 10.68 204.75 5

Great White Heron NWR Federal FWS Natural Heritage Member 837.79 837.79 100

J.N. Ding Darling NWR Federal FWS Natural Heritage Member 1.10 32.67 3

Key West NWR Federal FWS Natural Heritage Member 759.69 850.14 89

Laguna Atascosa NWR Federal FWS Natural Heritage Eligible 7.49 930.95 1

Lower Rio Grande Valley NWR Federal FWS Natural Heritage Eligible 17.04 12,129.37 0

Lower Suwannee NWR Federal FWS Natural Heritage Member 55.31 338.99 16

National Key Deer Refuge Federal FWS Natural Heritage Member 557.08 557.08 100

San Bernard NWR Federal FWS Natural Heritage Member 0.02 135.60 0

Shell Keys NWR Federal FWS Natural Heritage Member 0.02 0.02 100

St. Marks NWR Federal FWS Natural Heritage Member 107.58 446.90 24

St. Vincent NWR Federal FWS Natural Heritage Member 0.08 49.13 0

Ten Thousand Islands NWR Federal FWS Natural Heritage Member 18.03 140.36 13

National Estuarine Research Reserves

Mission-Aransas NERR Partnership UTMSI and 

NOAA Natural Heritage Eligible 15.89 748.66 2 

Apalachicola NERR Partnership FDEP and 

NOAA Natural Heritage Eligible 1.17 951.21 0 
Table 4.7-1. National System Marine Protected Areas Within or Partially Within the Area of Interest (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-83

Site Government 

Level

Managing 

Agency

Primary 

Conservation Focus Status

Area 

within AOI 

(km2)

Total Area 

(km2

) 

Percentage 

within AOI

Rookery Bay NERR Partnership FDEP and 

NOAA Natural Heritage Member 134.43 388.21 35

State Designated MPAs

Alligator Harbor Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 1.80 58.04 3

Anclote Key State Park State, Florida FDEP Natural Heritage Eligible 34.66 49.23 70

Apalachicola Bay Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 0.11 416.16 0

Atchafalaya Delta WMA and Game Preserve State, Florida LDWF Natural Heritage Eligible 539.51 555.71 97

Bahia Honda State Park State, Florida FDEP Natural Heritage Eligible 1.98 1.98 100

Big Bend Seagrasses Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 2,676.31 2,746.92 97

Big Bend WMA State, Florida FWC Sustainable 

Production Eligible 0.24 269.97 0 

Caladesi Island State Park State, Florida FDEP Natural Heritage Eligible 0.33 9.96 3

Camp Helen State Park State, Florida FDEP Natural Heritage Eligible 0.10 0.74 14

Cape Romano – Ten Thousand Islands 

Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 68.85 207.55 33

Cayo Costa State Park State, Florida FDEP Natural Heritage Eligible 6.48 9.69 67

Cedar Key Scrub State Reserve State, Florida FDEP Natural Heritage Eligible 5.26 19.81 27

Cedar Key Scrub WMA State, Florida FWC Sustainable 

Production Eligible 4.84 20.19 24

Chassahowitzka WMA State, Florida FWC Sustainable 

Production Eligible 8.65 135.78 6 

Coupon Bight Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 18.65 18.65 100

Crystal River Preserve State Park State, Florida FDEP Natural Heritage Eligible 27.67 112.91 25

Curry Hammock State Park State, Florida FDEP Sustainable 

Production Eligible 3.91 3.91 100

Don Pedro Island State Park State, Florida FDEP Natural Heritage Eligible 0.02 1.02 2

Dr. Julian G. Bruce St. George Island State 

Park State, Florida FDEP Natural Heritage Eligible 0.38 8.17 5 

Econfina River State Park State, Florida FDEP Natural Heritage Eligible 0.75 18.34 4

Estero Bay Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 0.45 43.26 1

Florida Keys Wildlife and Environmental Area State, Florida FWC Natural Heritage Eligible 7.43 10.45 71
Table 4.7-1. National System Marine Protected Areas Within or Partially Within the Area of Interest (continued) 

Tables-84 Tables

Site Government 

Level

Managing 

Agency

Primary 

Conservation Focus Status

Area 

within AOI 

(km2)

Total Area 

(km2

) 

Percentage 

within AOI

Fort Pickens State Park Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 100.05 125.31 80

Fort Zachary Taylor State Historic Site State, Florida FDEP Natural Heritage Eligible 0.22 0.22 100

Gasparilla Island State Park State, Florida FDEP Natural Heritage Eligible 0.33 0.51 65

Gasparilla Sound – Charlotte Harbor Aquatic 

Preserve State, Florida FDEP Natural Heritage Eligible 0.47 338.78 0 

Grayton Beach State Park State, Florida FDEP Natural Heritage Eligible 0.004 8.98 0

Honeymoon Island State Park State, Florida FDEP Natural Heritage Eligible 4.65 11.44 41

Idle Speed Manatee Protection Zones State, Florida FWC Natural Heritage Eligible 0.47 14.48 3

Isles Dernieres Barrier Islands Refuge State, Florida LDWF Sustainable 

Production Eligible 1.64 12.02 14

Lemon Bay Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 6.13 26.85 23

Lovers Key State Recreation Area State, Florida FDEP Natural Heritage Eligible 0.94 5.37 18

Marsh Island WMA and Game Preserve State, Florida LDWF Sustainable 

Production Eligible 0.01 285.57 0 

Maximum 25 mph Manatee Protection Zones State, Florida FWC Natural Heritage Eligible 0.36 42.84 1

Maximum 30 mph in Channel/Slow Speed or 

20 mph Outside Channel Manatee Protection 

Zones

State, Florida FWC Natural Heritage Eligible 14.03 115.81 12

Pass a Loutre WMA State, Florida LDWF Sustainable 

Production Eligible 156.74 465.23 34

Pine Island Sound Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 0.52 227.71 0

Pinellas County Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 1,038.60 1,420.08 73

Regina Underwater Archaeological Preserve State, Florida FDHR Cultural Heritage Eligible 0.02 0.02 66

Rockefeller WMA and Game Preserve State, 

Louisiana LDWF Sustainable Production Eligible 23.59 346.30 7 

Rookery Bay Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 65.60 234.18 28

Slow Speed Manatee Protection Zones State, Florida FWC Natural Heritage Eligible 5.72 474.12 1

SS Tarpon Underwater Archaeological 

Preserve State, Florida FDHR Cultural Heritage Eligible 0.58 0.58 100

St. Andrews State Park State, Florida FDEP Natural Heritage Eligible 0.06 4.72 1

St. Andrews State Park Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 71.98 96.38 75

St. Joseph Bay Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 131.96 265.45 50
Table 4.7-1. National System Marine Protected Areas Within or Partially Within the Area of Interest (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-85

Site Government 

Level

Managing 

Agency

Primary 

Conservation Focus Status

Area 

within AOI 

(km2)

Total Area 

(km2

) 

Percentage 

within AOI

St. Martins Marsh Aquatic Preserve State, Florida FDEP Natural Heritage Eligible 67.33 127.13 53

Stump Pass Beach State Park State, Florida FDEP Natural Heritage Eligible 0.84 1.02 82

Topsail Hill Preserve State Park State, Florida FDEP Natural Heritage Eligible 0.09 6.63 1

USS Massachusetts (BB-2) Underwater 

Archaeological Preserve State, Florida FDHR Cultural Heritage Eligible 0.21 0.21 100

Vamar Underwater Archaeological Preserve State, Florida FDHR Cultural Heritage Eligible 0.58 0.58 100

Waccasassa Bay State Preserve State, Florida FDEP Natural Heritage Eligible 19.39 137.49 14

Werner-Boyce Salt Springs State Park State, Florida FDEP Natural Heritage Eligible 5.55 16.02 35

AOI = Area of Interest; FDEP = Florida Department of Environmental Protection; FDHR = Florida Division of Historical Resources; FWC = Florida 

Fish and Wildlife Conservation Commission; FWS = Fish and Wildlife Service; HAPC = Habitat Area of Particular Concern; km2

 = square 

kilometers; LDWF = Louisiana Department of Wildlife and Fisheries; MPA = marine protected area; mph = miles per hour; NERR = National 

Estuarine Research Reserve; NMFS = National Marine Fisheries Service; NMS = National Marine Sanctuary; NOAA = National Oceanic and 

Atmospheric Administration; NPS = National Park Service; NWR = National Wildlife Refuge; ONMS = Office of National Marine Sanctuaries; 

UTMSI = University of Texas at Austin Marine Science Institute; WMA = Wildlife Management Area.
Tables-86 Tables

Table 4.9-1. 2014 Economic Impacts of the Gulf of Mexico Region Seafood Industry (thousands of dollars) (From: USDOC, NMFS, 2016d) 

State Revenue Landings Jobs Sales Income Valued Added

Alabama 68,793 15,069 660,627 251,520 333,185

Florida 203,372 92,858 18,317,052 3,434,238 6,135,060

Louisiana 451,371 44,066 2,220,879 816,203 1,115,858

Mississippi 25,995 4,714 198,608 79,501 102,731

Texas 278,353 33,880 2,857,586 826,213 1,238,477

Totals 1,027,884 190,587 24,254,752 5,407,675 8,925,311

Table 4.9-2. Total Landings and Landings of Key Species/Species Groups (thousands of pounds) (From: USDOC, NMFS, 2016d) 

Key Species/ 

Group

Year

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Blue Crab 50,041 67,481 57,964 49,258 61,277 41,240 55,606 50,409 46,940 47,765

Menhaden 815,495 901,398 1,005,325 927,517 1,002,579 753,442 1,398,654 1,078,139 1,021,526 769,943

Mullets 9,023 12,727 8,933 10,609 11,303 8,963 14,233 10,772 13,482 13,604

Oysters 20,174 19,674 22,518 20,723 22,829 15,824 18,742 19,948 19,249 16,525

Red Snapper 4,109 4,637 2,998 2,370 2,503 3,259 3,567 3,994 5,306 5,722

Shrimp 216,291 288,973 225,163 188,806 250,572 178,902 221,469 203,328 205,993 206,774

Stone Crab 4,534 4,806 5,893 6,169 5,407 5,112 5,482 5,226 3,778 1,890

Tunas 3,050 2,851 3,426 1,786 2,836 1,322 1,588 3,031 2,094 1,757

Finfish Total 842,453 930,705 1,027,990 950,842 1,025,854 771,856 1,425,029 1,103,909 1,049,688 799,573

Shellfish Total 291,040 380,934 311,538 264,956 340,085 241,078 301,299 278,911 275,960 272,954

Total Landings 1,133,493 1,311,639 1,339,528 1,215,798 1,365,939 1,012,934 1,726,328 1,382,820 1,325,648 1,072,527
Gulf of Mexico G&G Activities Programmatic EIS Tables-87

Table 4.9-3. Primary Commercial Fishing Methods, Target Species, Seasons, and General Areas Fished in the Gulf of Mexico

Fishing Method Target Species Primary Fishing Season Primary Fishing Area

Bottom trawling 

(including skimmer 

nets)

Brown shrimp, pink shrimp, white 

shrimp, seabob, royal red shrimp, 

and groundfish

Year-round depending on 

species and seasonal 

closures.

Soft bottom, shelf waters from nearshore to 

the upper slope off all Gulf Coast States 

depending on closed areas.

Purse netting Menhaden, butterfish, scads, blue 

runner, and Spanish sardines Spring and summer months

Menhaden inner shelf off Louisiana and 

Mississippi, scads and sardines inner shelf off 

Florida panhandle

Gillnetting Coastal sharks, mullet, Spanish 

mackerel, and black drum

Spring and summer 

depending on species and 

seasonal closures

Coastal waters, Alabama, Mississippi, 

Louisiana, prohibited in Florida and Texas

Hook-and-lining 

(bottom fishing and 

trolling)

Snappers, groupers, amberjacks, 

triggerfishes, sharks, king mackerel, 

Spanish mackerel, and cobia

Year-round; effort varies with 

species-specific closures

Oil platforms, artificial reefs, and natural hard 

bottom areas throughout the Gulf of Mexico’s

most activity inner and middle shelf.

Surface longlining Sharks, swordfish, tunas, and 

dolphinfish

Year-round with summer 

peaks

Open Gulf of Mexico seaward of 200 m

(656 ft)

Bottom longlining Groupers, snappers, tilefishes, and 

sharks

Year-round; effort varies with 

species specific closures

Outer shelf waters from Florida to Texas on 

suitable bottom type

Trapping Spiny lobster, stone crab, deep-sea 

red crab, and reef fishes

Stone crab (October to 

March); spiny lobster (July to 

March); fish (year-round)

Florida shelf waters
Tables-88 Tables

Table 4.9-4. Summary of Seasonal and/or Area Closures to Commercial Fishing in Federal Waters in 

the Gulf of Mexico

Closed or Restricted Area Location Gear Restrictions or Protection Measures

Closures of the Gulf group king 

mackerel gillnet fishery

Gulf of Mexico 

EEZ

Gillnet fishery for Gulf group king mackerel is closed July 1 

through Martin Luther King, Jr. holiday, and subsequent 

weekends and holidays with exceptions

Seasonal closure of the 

commercial fishery for gag, 

red, and black grouper

Gulf of Mexico 

EEZ

February 15-March 15 – no possession or sale of gag, red, and

black grouper if only commercial permit; OK if have both charter/

headboat and commercial permit and under bag limit

Closures of the commercial 

fishery for red snapper

Gulf of Mexico 

EEZ

Commercial fishery for red snapper closed from January 1 to 

February 1, and from the 10th of each month until the 1st on the 

succeeding month until quota met

Texas closure; royal red shrimp 

exception Offshore Texas Trawling is prohibited from May 15 to July 15 (except royal red shrimp beyond the 100-fathom contour)

Reef fish longline and buoy 

gear restricted area

Offshore Florida 

Panhandle and 

big bend areas

If using longline or buoy gear, catch is limited to bag limits for 

species, or where no bag limit, by 5%, by weight, of fish on board 

or landed

Reef fish stressed areas

Offshore all Gulf 

states

A powerhead may not be used to take Gulf reef fish. A roller trawl 

or fish trap are prohibited.

Southwest Florida seasonal 

trawl closure

Offshore SW 

Florida

Trawling is prohibited from January 1 to 1 hour after sunset 

May 20.

Tortugas shrimp sanctuary Offshore Florida 

Dry Tortugas Closed to trawling

Tortugas shrimp sanctuary Offshore Florida 

Dry Tortugas Closed to trawling except from April 11 to July 31

Tortugas shrimp sanctuary Offshore Florida 

Dry Tortugas Closed to trawling except from April 11 to September 30

Tortugas shrimp sanctuary Offshore Florida 

Dry Tortugas Closed to trawling except from May 26 to July 31

Shrimp/stone crab separation 

zones, Zone I Offshore Florida Unlawful to trawl for shrimp in the EEZ from October 5 to May 20

Shrimp/stone crab separation 

zones, Zone II Offshore Florida Restrictions for Florida’s waters are contained in Rule 46-38.001, Florida Administrative Code.

Shrimp/stone crab separation 

zones, Zone III Offshore Florida Unlawful to trawl for shrimp in the EEZ from October 5 to May 20

Shrimp/stone crab separation 

zones, Zone IV Offshore Florida

Unlawful to trap stone crab in EEZ from October 5 to December 1 

and April 2 to May 20; unlawful to trawl for shrimp in the EEZ from 

December 2 to April 1.

Shrimp/stone crab separation 

zones, Zone V Offshore Florida

Unlawful to trap stone crab in EEZ from October 5 to 

November 30 and March 16 to May 20; unlawful to trawl for 

shrimp in the EEZ from December 1 to March 15

Tortugas Marine Reserves 

Tortugas North and South

Offshore Florida 

Dry Tortugas Fishing for any species, and anchoring, are prohibited

Florida Middle Grounds HAPC Offshore Florida Fishing with bottom longline, bottom trawl, dredge, pot, or trap is 

prohibited year-round

Closure provisions applicable 

to the Steamboat Lumps and 

Madison and Swanson sites

Offshore Florida

From November to April, possession of Gulf reef fish prohibited 

except in transit, and fishing is prohibited, except for highly 

migratory species. From May to October, surface trolling is the 

only allowable fishing.

East and West Flower Garden 

Banks HAPC Offshore Texas Fishing with bottom longline, bottom trawl, dredge, pot, or trap is prohibited.

Alabama SMZ Offshore Alabama Gulf reef fishing restrictions on catch by vessel and gear type

EEZ = Economic Exclusion Zone; GMFMC = Gulf of Mexico Fishery Management Council; HAPC = Habitat Area of 

Particular Concern; MPA = Marine Protected Area; SMZ = Special Management Zone.

Note that regulations fluctuate on a regular basis and that current information on rules must be obtained from the GMFMC.

Modified from: 50 CFR § 622.34.
Gulf of Mexico G&G Activities Programmatic EIS Tables-89

Table 4.10-1. 2014 Recreational Gulf of Mexico Fishing Effort by Mode (thousands of dollars and trips) 

(From: USDOC, NMFS, 2016d) 

Trips Jobs Sales ($) Income($) Value Added ($)

Alabama 2,169 14,124 1,070,579 540,257 827,849

Louisiana 2,188 15,241 1,619,677 662,470 1,029,281

Mississippi 1,480 4,174 374,063 157,772 247,281

Texas N/A1 16,496 1,825,290 615,713 1,005,040

West Florida 15,179 70,109 7,467,774 3,161,122 4,868,743

Total 21,016 120,144 $12,357,383 $5,137,334 $7,978,194

1

N/A = not available. The Marine Recreational Program does not collect effort data for Texas.

Table 4.10-2. Economic Impacts of Gulf of Mexico Recreational Fishing Expenditures (thousands of 

angular trips) (From: USDOC, NMFS, 2016d) 

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

For-Hire 692 837 852 5,819 823 581 735 884 907 927

Private Boat 13,586 13,620 14,980 15,195 13,443 12,684 12,911 12,782 13,510 11,508

Shore 9,014 8,837 8,458 8,776 8,333 7,783 8,930 9,506 10,817 8,581

Total Trips 23,292 23,294 24,290 29,790 22,599 21,048 22,576 23,172 25,234 21,016

Table 4.10-3. Gulf of Mexico Recreational Harvest and Release of Key Species and Species Groups 

(thousands of fish) (From: USDOC, NMFS, 2016d) 

Key Species/Groups 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Drum (Atlantic 

croaker)

H 867 1,541 1,408 1,935 1,290 1,635 2,209 1,462 1,883 2,682

R 2,844 2,314 2,616 3,149 3,858 3,827 5,899 3,922 3,268 2,240

Drum (Gulf and 

southern kingfish)

H 1,426 1,250 1,137 1,307 1,066 1,420 941 918 1,623 705

R 781 926 843 729 576 625 539 535 474 356

Drum (sand and 

silver seatrouts)

H 2,159 2,239 3,185 3,556 4,314 4,700 5,962 5,055 3,013 2,500

R 724 1,538 1,910 1,989 2,444 1,807 2,541 2,474 1,851 481

Drum (spotted 

seatrout)

H 10,882 14,272 12,103 15,042 14,146 10,870 14,719 13,593 12,761 5,703

R 20,124 20,055 18,849 21,017 17,365 14,564 19,120 20,217 19,528 8,931

Porgies 

(sheepshead)

H 2,081 1,185 1,245 1,613 1,607 1,195 2,274 1,596 1,355 1,381

R 2,394 1,507 1,223 1,486 1,338 1,739 1,634 1,516 1,672 1,579

Red drum H 2,548 2,681 3,136 3,560 2,893 3,516 3,889 3,012 4,138 2,096

R 6,233 6,392 6,222 7,016 5,525 6,468 6,448 6,330 7,699 3,479

Red snapper H 884 1,035 1,270 720 828 368 557 626 1,291 500

R 2,194 2,831 3,259 2,112 2,145 1,436 1,521 1,424 2,824 1,785

Southern flounder H 623 538 701 538 691 801 857 836 1,103 491

R 195 171 239 121 193 220 222 309 339 72

Spanish mackerel H 1,192 1,759 1,330 1,895 1,504 1,564 1,534 1,834 3,352 1,718

R 1,374 2,855 2,104 2,040 1,634 2,477 1,941 1,441 4,158 2,779

Striped mullet H 1,081 1,103 1,150 1,258 743 1,666 1,900 2,356 2,984 2,365

R 165 141 158 146 226 127 313 204 194 293

H = harvest; R = release.
Tables-90 Tables

Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico (Data from: USDOC, NOAA, 2015; In the Bite, 2015; and 

Florida Sportsman, 2015)

Tournament Name Location Start End Targeted Species White Marlin Blue Marlin Black Marlin Sailfish Longbill Spearfish Roundscale Spearfish Swordfish Ridgeback Sharks Non-Ridgeback Sharks Small Coastal Sharks Pelagic Sharks Bluefin Tuna Bigeye Tuna

Albacore TuneYellowfin TunaSkipjack TunaCobiaWahooDolphinfishKing MackerelKingfish

2014

Alabama

Orange Beach Billfish Classic1 Orange Beach May 14 May 18 X X X X

Mobile BGFC Memorial Day 

Tournament Orange Beach May 23 May 26 X X X X X X X X 

Social Saltwater Series Orange Beach May 24 Sep 1 X

Gulf Coast Outboard Classic1 Orange Beach June 28 June 28 X X X

The Gulf Cup Blue Marlin Shootout Orange Beach July 4 July 4 X

Mobile BGFC Junior Angler 

Tournament Orange Beach July 4 July 5 X X X X X X X X 

Atlanta Saltwater Sportsman’s Club 

Orange Beach Shootout Orange Beach July 6 July 12 X X X X X X X X 

Blue Marlin Grand Championship1 Orange Beach July 10 July 13 X X X X

Mississippi Gulf Coast BGFC Ladies 

Tournament1 Orange Beach July 18 July 20 X X X X X X 

Alabama Deep-Sea Fishing Rodeo1 Dauphin Island July18 July 20 X X X X X X X X X X X

Mobile BGFC Billfish Limited 

Tournament1 Orange Beach July 25 July 27 X X X X X X X X 

Mobile BGFC Ladies Tournament1 Orange Beach Aug 1 Aug 3 X X X X X X X X

Gulf Coast White Marlin Shootout1 Orange Beach Aug 14 Aug 17 X X X X X X X X

Mobile BGFC Labor Day Tournament Orange Beach Aug 29 Sep 1 X X X X X X X X
Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-91

Tournament Name Location Start End Targeted Species White Marlin Blue Marlin Black Marlin Sailfish Longbill Spearfish Roundscale Spearfish Swordfish Ridgeback Sharks Non-Ridgeback Sharks Small Coastal Sharks Pelagic Sharks Bluefin Tuna Bigeye Tuna

Albacore TuneYellowfin TunaSkipjack TunaCobiaWahooDolphinfishKing MackerelKingfish

Louisiana

Louisiana Council of Underwater Dive 

Clubs Derby Board1 Metairie Jan 1 Dec 31 X X X X 

Houma Oilman’s Fishing Invitational1 Cocodrie May 22 May 24 X X

New Orleans BGFC Back to the Pass Port Eads May 24 May 25 X X X X X X X

Cajun Canyons Billfish Classic1 Venice May 27 June 1 X X X X X

New Orleans BGFC Cajun Canyons Port Eads May 30 May 31 X X X X X X X

Swollfest Fishing Rodeo1 Grand Isle June 5 June 7 X X X

Helldivers Spearfishing Rodeo1 Kenner June 5 June 8 X X X X

New Orleans BGFC Invitational1 Port Eads June 12 June 14 X X X X X X X

New Orleans BGFC Ladies 

Tournament Port Eads June 27 June 28 X X X X X X X 

The Gulf Cup Blue Marlin Shootout Venice July 4 July 4 X

Fourchon Oilman’s Association 

Fishing Tournament1 Port Fourchon July 10 July 12 X X X X X X X X 

New Orleans BGFC Regular 

Tournament1 Port Eads July 11 July 12 X X X X X X X 

Faux Pas Lodge Invitational1 Venice July 24 July 26 X X

New Orleans BGFC Grand Isle/Faux 

Pas Tournament1 Port Eads July 25 July 26 X X X X X X X 

New Orleans BGFC Empire 

Tournament Port Eads Aug 8 Aug 9 X X X X X X X 

New Orleans BGFC Labor Day 

Tournament Port Eads Aug 30 Aug 31 X X X X X X X 

New Orleans BGFC Last Tournament Port Eads Sep 13 Sep 14 X X X X X X X

Mississippi
Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico (continued) 

Tables-92 Tables

Tournament Name Location Start End Targeted Species White Marlin Blue Marlin Black Marlin Sailfish Longbill Spearfish Roundscale Spearfish Swordfish Ridgeback Sharks Non-Ridgeback Sharks Small Coastal Sharks Pelagic Sharks Bluefin Tuna Bigeye Tuna

Albacore TuneYellowfin TunaSkipjack TunaCobiaWahooDolphinfishKing MackerelKingfish

Mississippi Gulf Coast Billfish Classic1 Biloxi June 5 June 7 X X X X X

Mississippi Gulf Coast BGFC Spring 

Tournament Biloxi June 20 June 22 X X X X X X 

Mississippi Deep-Sea Fishing Rodeo1 Gulfport July 3 July 6 X X X

The Gulf Cup Blue Marlin Shootout Gulfport July 4 July 4 X

Carl Legett Memorial Fishing 

Tournament1 Biloxi Aug 1 Aug 3 X X X X X X X X X X X 

Texas

Texas Shark Rodeo Texas Coast Mar 16 Dec 31 X X X

South Texas BGFC Blake Bunk 

Memorial Day Tournament

South Padre 

Island May 24 May 25 X X X X X X X X X 

South Texas BGFC Blake Bunk 

Memorial Day Tournament Port Mansfield May 24 May 25 X X X X X X X X X 

42nd Annual Hall of Fame2 Galveston May 24 June 1 X

South Texas BGFC First June 

Tournament

South Padre 

Island June 7 June 7 X X X X X X X X X 

South Texas BGFC First June 

Tournament Port Mansfield June 7 June 7 X X X X X X X X X 

South Texas BGFC Middle of June 

Tournament

South Padre 

Island June 21 June 21 X X X X X X X X X 

South Texas BGFC Middle of June 

Tournament Port Mansfield June 21 June 21 X X X X X X X X X 

Texas Billfish Championship1 Freeport June 25 June 28 X X X X

Tackle Time Fishing Tournament1 Texas City June 27 July 6 X X

The Gulf Cup Blue Marlin Shootout Galveston July 4 July 4 X

The Gulf Cup Blue Marlin Shootout Port Aransas July 4 July 4 X
Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-93

Tournament Name Location Start End Targeted Species White Marlin Blue Marlin Black Marlin Sailfish Longbill Spearfish Roundscale Spearfish Swordfish Ridgeback Sharks Non-Ridgeback Sharks Small Coastal Sharks Pelagic Sharks Bluefin Tuna Bigeye Tuna

Albacore TuneYellowfin TunaSkipjack TunaCobiaWahooDolphinfishKing MackerelKingfish

South Texas BGFC Fourth of July 

Tournament

South Padre 

Island July 4 July 5 X X X X X X X X X 

South Texas BGFC Fourth of July 

Tournament Port Mansfield July 4 July 5 X X X X X X X X X 

Bastante Tournament Rockport July 9 July 12 X X X X

Deep Sea Round Up1 Port Aransas July 11 July 12 X X X X X X

South Texas BGFC Middle of July 

Tournament

South Padre 

Island July 12 July 12 X X X X X X X X X 

South Texas BGFC Middle of July 

Tournament Port Mansfield July 12 July 12 X X X X X X X X X 

Poco Bueno1 Port O’Connor July 16 July 19 X X

Lone Star Shootout1 Port O’Connor July 25 July 26 X X X X X

South Texas BGFC Port Mansfield 

Fishing Tournament

South Padre 

Island July 25 July 26 X X X X X X X X X 

South Texas BGFC Port Mansfield 

Fishing Tournament Port Mansfield July 25 July 26 X X X X X X X X X 

Texas International Fishing 

Tournament1 Port Isabel July 30 Aug 3 X X X X X X X 

Texas International Fishing 

Tournament1

South Padre 

Island July 30 Aug 3 X X X X X X X 

Texas Legends Billfish Tournament Port Aransas Aug 6 Aug 10 X X X X X X

South Texas BGFC Middle of August 

Tournament

South Padre 

Island Aug 16 Aug 16 X X X X X X X X X 

South Texas BGFC Middle of August 

Tournament Port Mansfield Aug 16 Aug 16 X X X X X X X X X 

Texas Women Anglers Tournament1 Port Aransas Aug 23 Aug 23 X X X X
Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico (continued) 

Tables-94 Tables

Tournament Name Location Start End Targeted Species White Marlin Blue Marlin Black Marlin Sailfish Longbill Spearfish Roundscale Spearfish Swordfish Ridgeback Sharks Non-Ridgeback Sharks Small Coastal Sharks Pelagic Sharks Bluefin Tuna Bigeye Tuna

Albacore TuneYellowfin TunaSkipjack TunaCobiaWahooDolphinfishKing MackerelKingfish

South Texas BGFC Labor Day 

Tournament

South Padre 

Island Aug 30 Aug 31 X X X X X X X X X 

South Texas BGFC Labor Day 

Tournament Port Mansfield Aug 30 Aug 31 X X X X X X X X X 

South Texas BGFC Last Tournament South Padre 

Island Sep 13 Sep 13 X X X X X X X X X 

South Texas BGFC Last Tournament Port Mansfield Sep 13 Sep 13 X X X X X X X X X

Sharkathon1 Corpus Christi Sep 26 Sep 28 X X X

Florida

Crosthwait Fishing Tournament Palmetto May 16 May 18 X X X X X X X X X X

Gulf Breeze Optimist Club 39th 

Annual Fishing Rodeo1 Gulf Breeze May 17 May 18 X 

7th Annual Fire Charity Fishing 

Tournament2 Palmetto June 6 June 8 X X X X X 

Pensacola Junior Anglers 

Tournament1 Pensacola June 14 June 14 X X X X X X X X 

Atlanta Saltwater Sportsman’s Club 

Duel at Destin Destin June 18 June 21 X X X X X X X X 

Emerald Coast Blue Marlin Classic at 

Sandestin1 Destin June 18 June 22 X X X X X X 

Fort Walton Beach Sailfish Club 

Offshore Invitational Tournament1 Fort Walton Beach June 19 June 22 X X X X X X X 

River Energy Shark Frenzy Tarpon Springs June 27 June 29 X X

The Gulf Cup Blue Marlin Shootout Anna Maria July 4 July 4 X

The Gulf Cup Blue Marlin Shootout Destin July 4 July 4 X

Pensacola International Billfish 

Tournament1 Pensacola July 4 July 5 X X X X X X X X X 
Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-95

Tournament Name Location Start End Targeted Species White Marlin Blue Marlin Black Marlin Sailfish Longbill Spearfish Roundscale Spearfish Swordfish Ridgeback Sharks Non-Ridgeback Sharks Small Coastal Sharks Pelagic Sharks Bluefin Tuna Bigeye Tuna

Albacore TuneYellowfin TunaSkipjack TunaCobiaWahooDolphinfishKing MackerelKingfish

De Soto Fishing Tournament1 Bradenton July 11 July 13 X X X X X X X X

Yellowfin Billfish Classic1 Sarasota July 22 July 26 X X X X X X X X X X X

Crosthwait Memorial of Florida, West 

Coast Triple Crown Billfish Series Palmetto Aug 6 Aug 9 X X X X X X 

Pensacola Ladies Billfish Tournament1 Pensacola Aug 9 Aug 10 X X X X X X X X X

42nd Annual Old Salt All Release 

Loop Tournament1 St. Petersburg Aug 19 Aug 28 X X X X X X X X X X X 

Atlanta Saltwater Sportsman Club1 Apalachicola Aug 21 Aug 23 X X X X X

Suncoast Saltwater Shootout Sarasota Sep 17 Sep 20 X X X X X X

Atlanta Saltwater Sportsman’s Club1 Perdido Beach Sep 19 Sep 20 X X X X X X X X X

Bluewater Bay Marina Complex 

Swordfish Showdown Niceville Sep 27 Oct 25 X 

66th Annual Destin Fishing Rodeo2 Destin Oct 1 Oct 30 X X X X X X X X X

2015 (as of May 2015)

Alabama

Orange Beach Billfish Classic1 Orange Beach May 13 May 17 X X X

Mobile Big Game Fishing Club 

Memorial Day and Outboard Shootout Orange Beach May 22 May 25 X X X X X X X X X 

Mobile BGFC Junior Angler 

Tournament1 Orange Beach July 3 July 4 X X X X X X X X X 

Blue Marlin Grand Championship of 

the Gulf1 Orange Beach July 7 July 12 X 

Mobile BGFC Billfish Limited 

Tournament1 Orange Beach July 24 July 26 X X X X X X X X X X 

Mobile BGFC Ladies Tournament1 Orange Beach July 31 Aug 2 X X X X X X X X X
Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico (continued) 

Tables-96 Tables

Tournament Name Location Start End Targeted Species White Marlin Blue Marlin Black Marlin Sailfish Longbill Spearfish Roundscale Spearfish Swordfish Ridgeback Sharks Non-Ridgeback Sharks Small Coastal Sharks Pelagic Sharks Bluefin Tuna Bigeye Tuna

Albacore TuneYellowfin TunaSkipjack TunaCobiaWahooDolphinfishKing MackerelKingfish

Mobile BGFC Labor Day Tournament 

and Outboard Shootout Orange Beach Sep 4 Sep 7 X X X X X X X X X 

Louisiana

Madfin Shark Series Venice Mar 10 Mar 12 X X

Hawk’s Nest 10th Annual Wahoo 

Championship2,3 Cat Island April April X X 

New Orleans BGFC First Tournament1 Venice May 15 May 16 X X X X X X X

New Orleans BGFC First Tournament1 Port Eads May 15 May 16 X X X X X X X

Cajun Canyons Billfish Classic1 Venice May 26 May 31 X X X X X X

New Orleans BGFC Regular Club 

Tournament1 Venice May 29 May 30 X X X X X X X 

Helldivers Spearfishing Rodeo1 Kenner June 4 June 7 X X X X

Bubba Dove Memorial Fishing Rodeo Theriot June 5 June 7 X

New Orleans BGFC Invitational 

Tournament1 Venice June 11 June 13 X X X X X X X 

Swollfest Fishing Rodeo1 Grand Isle June 11 June 13 X

New Orleans BGFC Regular Club 

Tournament1 Venice July 10 July 11 X X X X X X X 

New Orleans BGFC Grand Isle/Faux 

Pas Tournament1 Venice July 24 July 25 X X X X X X X 

New Orleans BGFC Ladies 

Tournament Venice June 26 June 27 X X X X X X X 

New Orleans BGFC Regular Club 

Tournament1 Venice Aug 7 Aug 8 X X X X X X X 

New Orleans BGFC Regular Club 

Tournament1 Venice Aug 21 Aug 22 X X X X X X X 

New Orleans BGFC Last Tournament Venice Sep 5 Sep 6 X X X X X X X
Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico (continued) 

Gulf of Mexico G&G Activities Programmatic EIS Tables-97

Tournament Name Location Start End Targeted Species White Marlin Blue Marlin Black Marlin Sailfish Longbill Spearfish Roundscale Spearfish Swordfish Ridgeback Sharks Non-Ridgeback Sharks Small Coastal Sharks Pelagic Sharks Bluefin Tuna Bigeye Tuna

Albacore TuneYellowfin TunaSkipjack TunaCobiaWahooDolphinfishKing MackerelKingfish

Mississippi

Mississippi Gulf Coast Billfish Classic1 Biloxi June 1 June 7 X X X X X X X

Mississippi Deep Sea Fishing Rodeo1 Gulfport July 2 July 5 X X X X

Texas

4th Annual John Uhr Memorial Billfish 

Tournament1 Rockport July 8 July 11 X X X X X X 

The Lonestar Shootout1 Port O’Connor July 21 July 26 X X X X X

Texas International Fishing 

Tournament1 South Padre Island July 29 Aug 2 X X X X X X X 

Texas International Fishing 

Tournament1 Port Isabel July 29 Aug 2 X X X X X X X 

Florida

Cobia World Championships3 Destin Mar 20 May 10 X

Shark Rally Fort Myers Mar 28 Mar 29 X X X X

Bluewater Bay Marina Cobia 

Tournament3 Destin April 1 April 30 X 

Bluewater Bay Marina Cobia 

Tournament3 Pensacola April 1 April 30 X 

Hog Breaths Cobia Tournament3 Destin April 4 April 4 X

Sarasota Sertoma/SKA King Mackerel 

Tournament3 Sarasota April 12 April 13 X 

Wild West Kingfish Tournament3 Madeira Beach April 16 April 18 X

Half-Hitch Tackle Cobia Tournament Panama City 

Beach April 17 April 19 X 
Table 4.10-4. Summary of Recreational Fishing Tournaments in the Gulf of Mexico (continued) 

Tables-98 Tables

Tournament Name Location Start End Targeted Species White Marlin Blue Marlin Black Marlin Sailfish Longbill Spearfish Roundscale Spearfish Swordfish Ridgeback Sharks Non-Ridgeback Sharks Small Coastal Sharks Pelagic Sharks Bluefin Tuna Bigeye Tuna

Albacore TuneYellowfin TunaSkipjack TunaCobiaWahooDolphinfishKing MackerelKingfish

Clearwater Rotary Club’s Annual 

Kingfish Tournament3 Clearwater April 18 April 18 X 

Wild West Kingfish Tournament3 Madeira Beach May 14 May 16 X

32nd Annual Crosthwait Memorial 

Tournament2 Palmetto May 15 May 17 X X X X X X X X X X X X X X X 

Gulf Breeze Optimist Club 40th Annual 

Fishing Rodeo1 Gulf Breeze May 16 May 17 X 

Fort Walton Beach Sailfish Club1 Shalimar June 12 June 14 X X X X X X X X X X X

Emerald Coast Blue Marlin Classic at 

Sandestin1 Destin June 17 June 21 X X X X X X X 

Pensacola International Billfish 

Tournament1 Pensacola June 24 June 28 X X X X X 

Yellowfin Billfish Classic1 Sarasota July 28 Aug 1 X X X X X X X X X X X

Crosthwaits Extreme Billfish 

Tournament Bradenton Aug 11 Aug 15 X X X X X 

44th Annual Old Salt Loop Billfish 

Tournament1 Madeira Beach Aug 25 Aug 29 X X X X X X X X X X X 

Wild West Kingfish Tournament3 Madeira Beach Oct 8 Oct 10 X

Wild West Kingfish Tournament3 Madeira Beach Oct 15 Oct 17 X

Gulf Coast States

Marlin Duel Gulf States April 15 Aug 31 X X

BGFC = Big Game Fishing Club.

1 Annual tournament – appears in more than 1 year in the table. 2 Lists annual in the name but does not appear more than once in the table.

3 A non-sanctioned Atlantic Highly Migratory Species tournament. A sanctioned tournament has been registered with the National Marine Fisheries Service.

 
Gulf of Mexico G&G Activities Programmatic EIS Tables-99

Table 4.12-1. Recent Marine Mineral Projects in Florida, Louisiana, and Mississippi (From: USDOI, 

BOEM, 2016b) 

Location Date Lease or 

MOA Executed

Cubic Yards 

Authorized

Miles of Shoreline 

Restored

Collier County, Florida May 2015 500,000* 7.5*

Longboat Key, Florida October 2012 466,500 9.8

Pinellas County, Florida July 2011 1,800,000 8.07

Whiskey Island, Louisiana May 2015 13,400,000 4.6

Caminada Headlands II, Louisiana March 2014 6,100,000 8.0

Caminada Headlands, Louisiana August 2012 5,200,000 6.0

Cameron Parish, Louisiana August 2012 5,000,000 8.0

Raccoon Island, Louisiana December 2010 750,000 1.2

Hancock, Harrison, and Jackson 

Counties, Mississippi August 2016 N/A N/A

MOA = Memorandum of Agreement; N/A = Not available.

* = proposed as project; have not yet obtained Finding of No Significant Impact (FONSI). 

Table 4.13-1. 2012 Economic Impact of the Gulf of Mexico on Coastal Communities (From: USDOC, 

NOAA, n.d.)

Sector Number of 

Establishments Total Employment Total Wages (in million $)

GDP 

(in million $)

Living Resources 1,146 12,913 393 1,446

Marine Construction 750 16,984 1,027 2,050

Marine Transportation 2,023 81,003 5,072 11,149

Offshore Mineral Extraction 3,393 131,289 19,513 131,003

Ship and Boat Building 567 40,408 2,289 3,552

Tourism and Recreation 17,267 298,558 5,653 11,977

Totals – All Sectors 25,146 581,155 33,947 161,177

GDP = gross domestic product.

Table 4.13-2. Population Living in Gulf of Mexico Coastal Watershed Communities (1970 to 2010) 

(From: USDOC, Census Bureau, 2002, 2012; USDOC, NOAA, n.d.)

State 1970 1990 2010 Percent Change

1970-1990

Percent Change 

1990-2010

Alabama 3,444,165 4,040,587 4,779,736 17.3 18.2

Gulf Coast Area1 531,447 640,468 764,613 20.5 19.4

Florida 6,789,443 12,937,926 18,801,310 90.6 45.3

Gulf Coast Area1 4,267,709 7,863,816 10,943,232 84.3 39.2

Louisiana 3,641,306 4,219,973 4,533,372 15.9 7.4

Gulf Coast Area1 2,806,882 3,313,024 3,573,854 18.0 7.9

Mississippi 2,216,912 2,573,216 2,967,297 16.1 15.3

Gulf Coast Area1 395,504 508,713 628,502 28.6 23.5

Texas 14,229,191 20,851,820 25,145,561 46.5 20.6

Gulf Coast Area1 3,607,130 5,581,687 8,287,623 54.7 48.5

State Total 30,321,017 44,623,522 56,227,276 47.2 26.0

Gulf Coast Total1 11,608,672 17,907,708 24,197,824 54.3 35.1

BOEM = Bureau of Ocean Energy Management; NOAA = National Oceanic and Atmospheric Administration.

1 Gulf Coast Area as defined by NOAA differs slightly from the Economic Impact Areas identified by BOEM.
Tables-100 Tables

Table 4.13-3. 2012 Minority Populations in Geographic Areas Associated with Ports Serving the Geological and Geophysical Industry in the 

Area of Interest (From: USDOC, Census Bureau, n.d.)

Port/Location Total 

Population

Percent of Total Population

White

Black or 

African 

American

Alaska 

Native or 

American 

Indian

Asian

Native 

Hawaiian 

and 

Other 

Pacific 

Islander

Some 

Other 

Race 

Alone

Two 

or 

More 

Races

Total 

Percent 

Racial 

Minority

Hispanic 

or 

Latino1

United States 311,609,369 74.0 12.6 0.8 4.9 0.2 4.7 2.8 26.0 16.6

Port Fourchon

Louisiana 4,573,595 62.9 32.0 0.6 1.6 0.1 1.1 1.7 37.1 4.4

Houma-Bayou Cane-Thibodaux 

MSA 208,590 75.0 16.0 4.0 0.8 0.3 1.4 2.5 25.0 4.0

Lafourche Parish 96,860 80.2 13.5 2.3 0.7 0.0 1.3 2.0 19.8 3.9

Texas

Texas 25,644,550 74.6 11.8 0.5 3.9 0.1 6.8 2.3 25.4 38.0

Houston-Sugar Land-Baytown MSA 6,085,873 65.7 17.2 0.4 6.7 0.1 7.9 2.0 34.3 35.7

City of Galveston 47,689 72.9 19.1 0.2 4.1 0.0 1.7 2.0 27.1 30.2

MSA = metropolitan statistical area

1 Hispanic or Latino origin is considered an ethnicity not a race. Individuals who identify themselves as being of Hispanic or Latino origin may 

be of any race.
Gulf of Mexico G&G Activities Programmatic EIS Tables-101

Table 4.13-4. 2012 Low-Income Populations in Geographic Areas Associated with Ports Serving the 

Geological and Geophysical Industry in the Area of Interest (From: USDOC, Census 

Bureau, n.d.)

Port/Location Percent Low 

Income

Per Capita 

Income ($)

Median Household 

Income ($)

United States 15.7 27,385 51,771

Port Fourchon

Louisiana 19.6 23,792 43,484

Houma-Bayou Cane-Thibodaux 

MSA 16.4 23,731 48,270

Lafourche Parish 13.9 24,403 47,843

Port of Galveston

Texas 18.1 25,268 50,776

Houston-Sugar Land-Baytown MSA 13.4 28,059 56,080

City of Galveston 24.7 23,731 48,270

MSA = metropolitan statistical area.
Tables-102 Tables

Table 4.13-5. Average Survey Incremental Cost and Percent Cost Change by Alternative

Survey Type Average 

Survey Cost* Alternative A1 Alternative B2 Alternative C3,4 Alternative D3,5 Alternative E3,6 Alternative F3,7

Airgun HRG $360,000 $0 

(0%)

$70,000-$80,000

(18.6%-21.9%)

$70,000-$90,000

(18.6% - 25.6%)

$70,000-$100,000

(18.6%-26.4%)

$70,000-$90,000

(18.6%-25.6%)

$70,000-$90,000

(18.6%-25.6%)

Non-Airgun 

HRG $640,000 $0

(0%)

$0 

(0%)

$58,000-$68,000

(9.0%-10.7%)

$59,000-$75,000

(9.2%-11.7%)

$58,000-$68,000

(9.0%-10.7%)

$58,000-$68,000

(9.0%-10.7%)

VSP $300,000 $0

(0%)

$62,000-$71,000

(23.0%-26.3%)

$62,000-$82,000

(23.0%-30.4%)

$63,000-$84,000

(23.3%-31.1%)

$62,000-$82,000

(23.0%-30.4%)

$62,000-$82,000

(23.0%-30.4%)

2D $22.2 M $0

(0%)

$2.46-$5.33 M

(11.1%-24.1%)

$0.75-$1.50 M

(3.4%-6.8%)

$0.88-$1.85 M

(4.0%-8.3%)

$0.75-$1.50 M

(3.4%-6.8%)

$0.75-$1.50 M

(3.4%-6.8%)

3D $49.8 M $0

(0%)

$5.52-$12.46 M

(11.1%-25.0%)

$1.06-$3.87 M

(2.1%-7.8%)

$1.31-$5.25 M

(2.6%-10.6%)

$1.06-$3.87 M

(2.1%-7.8%)

$1.06-$3.87 M

(2.1%-7.8%)

WAZ $165.7-$170.7 M $0

(0%)

$22.78-$48.29 M

(13.7%-28.3%)

$7.22-$16.46 M 

(4.4%-9.6%)

$9.32-$22.09 M

(5.6%-12.9%)

$7.22-$16.46 M 

(4.4%-9.6%)

$7.22-$16.46 M 

(4.4%-9.6%)

OBS $44.0-$68.0 M $0

(0%)

$4.48-$17.39 M

(10.2%-25.6%)

$0.59-$2.94 M

(1.3%-4.3%)

$0.69-$3.59 M

(1.6%-5.3%)

$0.59-$2.94 M

(1.3%-4.3%)

$0.59-$2.94 M

(1.3%-4.3%)

% = percent; 2D = two dimensional; 3D = three dimensional; ft = feet; HRG = high-resolution geophysical; m = meter; M = million; OBS = ocean bottom survey; 

PAM = passive acoustic monitoring; PSO = protected species observer; WAZ = wide azimuth

* Average survey costs were derived from pre-settlement costs. 1 The PSO Program was previously required; therefore, for Alternative A, there would be no increase in cost. 2 The costs for Alternative B include mitigations for the expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility in 

>100 m (328 ft) of water. The minimum separation distance mitigation is expected to cost industry a 10-25% loss in efficiency (IAGC, 2014). The ranges 

reported here include that loss in efficiency. Note that HRG and VSP surveys are not expected to be affected by the minimum separation distance mitigation. 3 Non-airgun HRG survey protocol are applied to these costs. 4 The costs for Alternative C include mitigations for the expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility in 

>100 m (328 ft) of water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. 5 The costs for Alternative D include mitigations for the expanding the PSO Program to include manatees and dolphins as well as whales, including PAM in 

reduced visibility in >100 m (328 ft) of water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. 6 The costs for Alternative E include mitigations for the expanding the PSO Program to include manatees as well as whales, including PAM in >100 m (328 ft) of 

water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. This does not include the 10% and 25% reduction in line miles. 7 The costs for Alternative F include mitigations for the expanding the PSO Program to include manatees as well as whales, including PAM in >100 m (328 ft) of 

water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. This does not include the reduction in surveys due to the closure 

area and associated buffer.
Gulf of Mexico G&G Activities Programmatic EIS Tables-103

Table 4.13-6. Total Discounted Survey Incremental Cost by Alternative from 2018-2027* 

Survey Type Alternative A2 Alternative B3 Alternative C4 Alternative D5 Alternative E6 Alternative F7

Airgun HRG1 $0 $2.17-$3.41 M $2.17-$3.89 M $2.14-$4.03 M $2.87-$3.73 M $2.17-$3.89 M

Non-Airgun HRG1 $0 $0 $16.74-$26.52 M $17.20-$28.93 M $22.14-$25.46 M $16.61-$26,52 M

VSP $0 $15.27-$25.34 M $15.27-$28.34 M $15.52-$29.05 M $20.94-$27.84 M $15.27-$28.34 M

2D $0 $0-$78.63 M $0-$20.01 M $0-$25.18 M $11.06-$19.25 M $0-$20.01 M

3D $0 $37.46-$549.82 M $7.19-$148.57 M $8.89-$209.55 M $43.37-$146.85 M $7.19-$148.57 M

WAZ $0 $408.45-$1,900.08 M $129.46-$582.17 M $167.11-$803.70 M $290.89-$606.12 M $129.46-$582.17 M

Total $0 $463.35-$2,557.28 M $154.09-$782.98 M $193.66-$1,071.50 M $369.12-$803.79 M $154.09-$782.98 M

% = percent; 2D = two dimensional; 3D = three dimensional; ft = feet; HRG = high-resolution geophysical; m = meter; M = million; PAM = passive acoustic 

monitoring; PSO = protected species observer; WAZ = wide azimuth

* Costs in this table are based on the forecasted annual number of surveys (Tables 2.7-1, 2.7-2, and 3.2-1) and survey incremental cost (Table 4.13.9-1). A 

7% discount rate was applied. 1 Based on historical data, BOEM assumed that 90% of forecasted HRG surveys would be non-airgun HRG surveys. 2 The PSO Program was previously required; therefore, for Alternative A, there would be no increase in cost. 3 The costs for Alternative B include mitigations for the expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility in 

>100 m (328 ft) of water, and lastly to include a 10% loss in efficiency due to buffer zone compliance. This 10% loss in efficiency is only expected to affect 

65% of surveys and has been factored into this analysis. 4 The costs for Alternative C include mitigations for the expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility in 

>100 m (328 ft) of water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. 5 The costs for Alternative D include mitigations for the expanding the PSO Program to include manatees and dolphins as well as whales, including PAM in 

>100 m (328 ft) of water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. 6 The costs for Alternative E include mitigations for the expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility in 

>100 m (328 ft) of water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. This does not include the 10% and 

25% reduction in line miles. 7 The costs for Alternative F include mitigations for the expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility in 

>100 m (328 ft) of water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. This does not include the reduction in surveys 

due to the closure area and associated buffer.
Tables-104 Tables

Table 4.13-7. Percent Change in Operational Efficiency by Alternative* 

Survey Type Alternative A1 Alternative B2 Alternative C3 Alternative D4 Alternative E5 Alternative F6 

Airgun HRG 0% 0.8% 0.8%-2.5% 1.1%-4.5% 0.8%-2.5% 0.8%-2.5%

Non-Airgun 

HRG 0% 0% 0.8%-2.5% 1.1%-3.5% 0.8%-2.5% 0.8%-2.5%

VSP 0% 0.8% 0.8%-2.5% 1.1%-3.5% 0.8%-2.5% 0.8%-2.5%

2D 0% 12.4%-27.4% 2.4%-5.0% 3.1%-7.1% 2.4%-5.0% 2.4%-5.0%

3D 0% 11.8%-26.8% 1.8%-7.5% 2.3%-10.6% 1.8%-7.5% 1.8%-7.5%

WAZ 0% 14.3%-29.3% 4.3%-8.7% 5.6%-12.4% 4.3%-8.7% 4.3%-8.7%

OBS 0% 10.8%-25.8% 0.8%-2.5% 1.1%-3.5% 0.8%-2.5% 0.8%-2.5%

% = percent; 2D = two dimensional; 3D = three dimensional; ft = feet; HRG = high-resolution geophysical; m = meter; 

OBS = ocean bottom survey; PAM = passive acoustic monitoring; PSO = protected species observer; VSP = vertical 

seismic profile; WAZ = wide azimuth

* These calculations are based on survey delays due to the proposed mitigations. 1 Assumes same efficiency as a typical survey’s reduced efficiency of 10%. Alternative A proposes no new 

mitigations and would not result in a loss of operational efficiency. 2 Assumes expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility 

in >100 m (328 ft) of water. These numbers include an additional 10-25% loss in efficiency due to buffer zone 

compliance for the minimal distance requirement. 3 Assumes expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility 

in >100 m (328 ft) of water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. 4 Assumes expanding the PSO Program to include manatees and dolphins as well as whales, including PAM in 

reduced visibility in >100 m (328 ft) of water and expanding the PAM to include the Mississippi Canyon and 

De Soto Canyon blocks. 5 Assumes expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility 

in >100 m of water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. This 

does not include the 10% and 25% reductions in line miles. 6 Assumes expanding the PSO Program to include manatees as well as whales, including PAM in reduced visibility 

in >100 m (328 ft) of water and expanding the PAM to include the Mississippi Canyon and De Soto Canyon blocks. 

This does not include the reduction in surveys due to the closure area and associated buffer.
KEYWORD INDEX

Keyword Index Keywords-3 

KEYWORD INDEX

2D Seismic Exploration Survey, 1-7, 1-9, 3-4, 3-5, 3-6, 3-18, 3-20, 3-22, 3-23, 3-27, 3-34, 3-40, 4-3, 

4-25, 4-26, 4-42, 4-46, 4-48, 4-49, 4-50, 4-58, 4-64, 4-130, 4-143, 4-148, 4-216, 4-278, 4-292, 

4-337, 4-359, 4-364, 4-381, 4-402, 4-428, 4-438, 4-442, 4-447, 4-451, 4-456

3D Seismic Exploration Survey, 1-7, 1-9, 1-18, 3-4, 3-5, 3-6, 3-18, 3-20, 3-22, 3-23, 3-27, 3-34, 3-40, 

4-3, 4-12, 4-25, 4-26, 4-42, 4-46, 4-47, 4-48, 4-49, 4-50, 4-58, 4-64, 4-72, 4-130, 4-143, 4-148, 

4-189, 4-227, 4-255, 4-278, 4-337, 4-364, 4-402, 4-428, 4-438, 4-442, 4-447, 4-451, 4-456

4D (Time-Lapse) Survey, 3-5, 3-6, 3-22, 3-23, 3-27, 4-3, 4-25, 4-26, 4-46, 4-64, 4-130, 4-143, 4-148, 

4-189, 4-227, 4-255, 4-278, 4-337, 4-364, 4-402

Accidental Fuel Spill, xiv, xv, xvi, xvii, xviii, xix, xx, xxiv, xxv, xxvi, 2-35, 2-36, 2-37, 2-38, 3-34, 3-36, 

3-37, 3-39, 3-40, 3-41, 3-42, 3-43, 3-44, 3-45, 3-47, 3-48, 4-24, 4-73, 4-75, 4-76, 4-86, 4-87, 4-97, 

4-98, 4-104, 4-105, 4-107, 4-108, 4-111, 4-112, 4-119, 4-120, 4-123, 4-124, 4-125, 4-129, 4-149, 

4-159, 4-166, 4-171, 4-172, 4-174, 4-176, 4-179, 4-182, 4-196, 4-197, 4-206, 4-207, 4-209, 4-210, 

4-212, 4-215, 4-216, 4-217, 4-222, 4-230, 4-236, 4-237, 4-238, 4-239, 4-241, 4-243, 4-244, 4-245, 

4-249, 4-260, 4-268, 4-272, 4-274, 4-276, 4-279, 4-281, 4-282, 4-283, 4-289, 4-298, 4-304, 4-305, 

4-306, 4-308, 4-310, 4-312, 4-313, 4-314, 4-316, 4-320, 4-321, 4-326, 4-328, 4-330, 4-331, 4-333, 

4-334, 4-336, 4-343, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 4-360, 

4-361, 4-363, 4-367, 4-368, 4-371, 4-373, 4-376, 4-377, 4-379, 4-380, 4-382, 4-383, 4-388, 4-393, 

4-394, 4-395, 4-396, 4-401, 4-407, 4-408, 4-412, 4-414, 4-415, 4-416, 4-417, 4-418, 4-419

Accidental Spills, 2-24, 3-38, 4-74, 4-87, 4-198, 4-230, 4-231, 4-249, 4-261, 4-281, 4-283, 4-321, 

4-322, 4-344, 4-408, 4-418, 4-419, 4-429, 4-440, 4-444, 4-448, 4-453, 4-458

Active Acoustic Sound Sources, xiv, xv, xvi, xxiv, xxv, 2-18, 2-32, 2-36, 2-37, 3-17, 3-18, 3-36, 3-41, 

3-43, 3-45, 3-47, 4-4, 4-23, 4-24, 4-25, 4-40, 4-45, 4-65, 4-77, 4-87, 4-89, 4-92, 4-93, 4-95, 4-102, 

4-103, 4-112, 4-118, 4-125, 4-129, 4-130, 4-132, 4-135, 4-138, 4-152, 4-160, 4-161, 4-163, 4-168, 

4-169, 4-170, 4-174, 4-175, 4-176, 4-178, 4-179, 4-182, 4-184, 4-185, 4-189, 4-190, 4-198, 4-199, 

4-203, 4-204, 4-205, 4-208, 4-210, 4-212, 4-213, 4-214, 4-216, 4-217, 4-222, 4-224, 4-225, 4-229, 

4-231, 4-236, 4-237, 4-238, 4-239, 4-241, 4-242, 4-244, 4-245, 4-249, 4-250, 4-251, 4-252, 4-262, 

4-263, 4-268, 4-269, 4-270, 4-271, 4-273, 4-274, 4-276, 4-278, 4-279, 4-280, 4-283, 4-289, 4-291, 

4-292, 4-293, 4-294, 4-300, 4-302, 4-303, 4-304, 4-305, 4-306, 4-307, 4-308, 4-309, 4-310, 4-312, 

4-313, 4-314, 4-336, 4-337, 4-338, 4-345, 4-348, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 

4-357, 4-358, 4-359, 4-360, 4-363, 4-364, 4-366, 4-367, 4-369, 4-371, 4-372, 4-375, 4-378, 4-379, 

4-380, 4-381, 4-382

Aeromagnetic Survey, 3-6, 3-25, 4-69, 4-70, 4-81, 4-90, 4-92, 4-93, 4-145, 4-146, 4-154, 4-161, 

4-162, 4-163, 4-258, 4-259, 4-264, 4-266, 4-269, 4-271, 4-274, 4-405

Air Quality, xv, 2-24, 2-25, 4-5 

Aircraft Traffic and Noise, xiv, xv, xvi, xviii, xix, xx, xxv, 2-23, 2-33, 2-36, 3-17, 3-25, 3-36, 3-37, 3-41, 

3-47, 4-4, 4-24, 4-69, 4-73, 4-81, 4-83, 4-90, 4-92, 4-93, 4-95, 4-97, 4-101, 4-103, 4-104, 4-106, 

4-107, 4-110, 4-111, 4-112, 4-119, 4-122, 4-123, 4-125, 4-129, 4-145, 4-149, 4-154, 4-161, 4-162, 
Keywords-4 Gulf of Mexico G&G Activities Programmatic EIS

4-163, 4-164, 4-165, 4-168, 4-169, 4-170, 4-172, 4-174, 4-175, 4-176, 4-178, 4-179, 4-241, 4-249, 

4-258, 4-260, 4-265, 4-270, 4-271, 4-273, 4-274, 4-276, 4-278, 4-279, 4-280, 4-282, 4-283, 4-310, 

4-401, 4-408

Airgun, x, xi, xii, xiii, xvii, xviii, xix, xx, xxii, xxiv, xxv, 1-8, 1-10, 1-11, 1-18, 1-21, 1-25, 1-29, 2-5, 2-6, 

2-10, 2-11, 2-13, 2-15, 2-17, 2-18, 2-19, 2-21, 2-26, 2-27, 2-28, 2-32, 2-33, 2-35, 2-36, 2-37, 2-39, 

2-40, 2-41, 2-42, 2-44, 2-45, 2-46, 2-48, 2-49, 3-3, 3-5, 3-6, 3-9, 3-17, 3-18, 3-19, 3-22, 3-23, 3-24, 

3-25, 4-3, 4-4, 4-9, 4-23, 4-24, 4-25, 4-26, 4-27, 4-29, 4-30, 4-33, 4-35, 4-37, 4-38, 4-39, 4-40, 

4-41, 4-42, 4-43, 4-44, 4-45, 4-46, 4-47, 4-48, 4-49, 4-50, 4-53, 4-55, 4-56, 4-57, 4-58, 4-59, 4-60, 

4-61, 4-62, 4-63, 4-65, 4-73, 4-77, 4-78, 4-86, 4-87, 4-88, 4-89, 4-90, 4-91, 4-92, 4-93, 4-94, 4-95, 

4-96, 4-97, 4-98, 4-99, 4-100, 4-101, 4-102, 4-103, 4-104, 4-105, 4-106, 4-107, 4-109, 4-110, 

4-111, 4-112, 4-114, 4-118, 4-119, 4-120, 4-121, 4-123, 4-125, 4-129, 4-130, 4-131, 4-132, 4-133, 

4-134, 4-135, 4-136, 4-137, 4-138, 4-139, 4-140, 4-141, 4-142, 4-143, 4-144, 4-149, 4-152, 4-159, 

4-161, 4-162, 4-163, 4-164, 4-165, 4-166, 4-167, 4-168, 4-169, 4-170, 4-172, 4-174, 4-176, 4-177, 

4-179, 4-182, 4-185, 4-186, 4-187, 4-188, 4-189, 4-190, 4-191, 4-196, 4-198, 4-199, 4-200, 4-204, 

4-205, 4-206, 4-207, 4-208, 4-210, 4-212, 4-214, 4-215, 4-217, 4-222, 4-224, 4-225, 4-231, 4-236, 

4-237, 4-238, 4-242, 4-243, 4-245, 4-249, 4-250, 4-251, 4-252, 4-253, 4-256, 4-260, 4-262, 4-263, 

4-265, 4-269, 4-270, 4-271, 4-272, 4-273, 4-274, 4-275, 4-276, 4-278, 4-279, 4-280, 4-281, 4-282, 

4-283, 4-289, 4-291, 4-292, 4-293, 4-294, 4-295, 4-298, 4-300, 4-302, 4-303, 4-304, 4-305, 4-311, 

4-314, 4-318, 4-322, 4-325, 4-326, 4-327, 4-328, 4-329, 4-330, 4-332, 4-336, 4-338, 4-339, 4-340, 

4-343, 4-345, 4-348, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 

4-360, 4-363, 4-364, 4-365, 4-366, 4-368, 4-371, 4-372, 4-374, 4-375, 4-376, 4-378, 4-379, 4-380, 

4-382, 4-389, 4-411, 4-413, 4-414, 4-416, 4-417, 4-437, 4-439, 4-442, 4-443, 4-444, 4-447, 4-448, 

4-451, 4-453, 4-455, 4-457, 5-3 

Alternative A, xii, xiii, xvi, xxi, 2-3, 2-7, 2-8, 2-9, 2-11, 2-12, 2-13, 2-15, 2-17, 2-22, 2-33, 2-34, 2-39, 

4-24, 4-30, 4-57, 4-60, 4-64, 4-66, 4-68, 4-70, 4-71, 4-72, 4-73, 4-75, 4-83, 4-87, 4-88, 4-89, 4-90, 

4-91, 4-92, 4-93, 4-94, 4-95, 4-96, 4-97, 4-98, 4-99, 4-100, 4-101, 4-102, 4-103, 4-104, 4-105, 

4-106, 4-108, 4-109, 4-110, 4-112, 4-113, 4-115, 4-118, 4-120, 4-121, 4-122, 4-123, 4-124, 4-129, 

4-138, 4-139, 4-140, 4-141, 4-142, 4-143, 4-145, 4-147, 4-148, 4-149, 4-151, 4-154, 4-155, 4-156, 

4-160, 4-161, 4-162, 4-163, 4-164, 4-165, 4-166, 4-167, 4-168, 4-169, 4-170, 4-171, 4-172, 4-173, 

4-174, 4-175, 4-176, 4-177, 4-178, 4-182, 4-190, 4-192, 4-193, 4-194, 4-195, 4-196, 4-197, 4-199,

4-201, 4-202, 4-203, 4-204, 4-206, 4-207, 4-208, 4-209, 4-210, 4-211, 4-212, 4-213, 4-214, 4-215, 

4-216, 4-217, 4-222, 4-223, 4-226, 4-230, 4-231, 4-232, 4-233, 4-235, 4-236, 4-237, 4-238, 4-239, 

4-240, 4-241, 4-242, 4-243, 4-244, 4-249, 4-253, 4-260, 4-261, 4-268, 4-269, 4-270, 4-271, 4-272, 

4-273, 4-274, 4-275, 4-276, 4-277, 4-278, 4-279, 4-280, 4-281, 4-282, 4-283, 4-289, 4-290, 4-296, 

4-298, 4-299, 4-300, 4-301, 4-302, 4-303, 4-304, 4-305, 4-306, 4-307, 4-309, 4-310, 4-311, 4-312, 

4-313, 4-314, 4-316, 4-317, 4-318, 4-320, 4-321, 4-325, 4-326, 4-327, 4-328, 4-329, 4-330, 4-331, 

4-332, 4-333, 4-334, 4-336, 4-339, 4-340, 4-341, 4-342, 4-343, 4-348, 4-350, 4-351, 4-352, 4-353, 

4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 4-360, 4-363, 4-364, 4-365, 4-366, 4-367, 4-371, 4-373, 

4-374, 4-376, 4-377, 4-378, 4-379, 4-380, 4-381, 4-382, 4-383, 4-384, 4-385, 4-387, 4-388, 4-390, 

4-393, 4-394, 4-395, 4-401, 4-404, 4-405, 4-408, 4-411, 4-412, 4-413, 4-414, 4-415, 4-416, 4-417, 

4-418, 4-419, 4-425, 4-426, 4-427, 4-428, 4-429, 4-436, 4-437, 4-440, 4-441, 4-442, 4-444, 4-445, 

4-446, 4-449, 4-454, 4-458, 4-462
Keyword Index Keywords-5 

Alternative B, xii, xiii, xxi, 1-11, 1-12, 2-3, 2-6, 2-8, 2-9, 2-10, 2-13, 2-14, 2-16, 2-18, 2-32, 2-40, 2-41, 

2-45, 4-88, 4-89, 4-90, 4-91, 4-92, 4-93, 4-94, 4-95, 4-96, 4-97, 4-98, 4-99, 4-100, 4-115, 4-160, 

4-161, 4-162, 4-163, 4-164, 4-165, 4-166, 4-167, 4-168, 4-171, 4-204, 4-205, 4-206, 4-207, 4-209, 

4-235, 4-236, 4-237, 4-269, 4-270, 4-271, 4-272, 4-273, 4-302, 4-303, 4-304, 4-305, 4-325, 4-326, 

4-327, 4-348, 4-349, 4-350, 4-351, 4-371, 4-372, 4-373, 4-374, 4-393, 4-394, 4-411, 4-412, 4-413, 

4-436, 4-437, 4-438, 4-439, 4-440, 4-441, 4-442

Alternative C, xii, xiii, xxi, 2-3, 2-11, 2-12, 2-13, 2-15, 2-16, 2-17, 4-99, 4-100, 4-101, 4-102, 4-103, 

4-104, 4-105, 4-106, 4-107, 4-108, 4-109, 4-110, 4-113, 4-118, 4-120, 4-168, 4-169, 4-170, 4-171, 

4-172, 4-173, 4-175, 4-177, 4-208, 4-209, 4-210, 4-211, 4-212, 4-214, 4-215, 4-237, 4-238, 4-239, 

4-240, 4-242, 4-243, 4-273, 4-274, 4-275, 4-277, 4-280, 4-281, 4-305, 4-306, 4-307, 4-309, 4-311, 

4-312, 4-327, 4-328, 4-329, 4-331, 4-332, 4-333, 4-351, 4-352, 4-353, 4-355, 4-356, 4-357, 4-359, 

4-374, 4-375, 4-376, 4-377, 4-378, 4-379, 4-380, 4-381, 4-413, 4-414, 4-415, 4-416, 4-417, 4-418, 

4-441, 4-442, 4-443, 4-444, 4-445, 4-447, 4-449, 4-452, 4-454, 4-456

Alternative D, xii, xxi, 2-3, 2-13, 2-15, 2-49, 4-106, 4-107, 4-108, 4-109, 4-172, 4-173, 4-210, 4-211, 

4-239, 4-240, 4-275, 4-276, 4-277, 4-307, 4-308, 4-309, 4-329, 4-330, 4-331, 4-353, 4-354, 4-355, 

4-377, 4-415, 4-416, 4-445, 4-446, 4-447, 4-448, 4-449

Alternative E, xii, xiii, xxi, xxiv, xxv, 2-3, 2-15, 2-16, 2-17, 2-33, 2-35, 2-36, 2-37, 2-49, 3-3, 4-8, 

4-109, 4-110, 4-111, 4-112, 4-113, 4-125, 4-173, 4-174, 4-175, 4-179, 4-211, 4-212, 4-213, 4-240, 

4-241, 4-242, 4-277, 4-278, 4-279, 4-280, 4-283, 4-309, 4-310, 4-311, 4-331, 4-332, 4-355, 4-356, 

4-357, 4-361, 4-378, 4-379, 4-399, 4-416, 4-417, 4-419, 4-449, 4-450, 4-451, 4-452, 4-453, 4-454

Alternative F, xiii, xvii, xxi, 2-3, 2-17, 2-19, 2-33, 2-35, 4-113, 4-114, 4-115, 4-116, 4-118, 4-119, 

4-120, 4-121, 4-125, 4-175, 4-176, 4-177, 4-179, 4-214, 4-215, 4-216, 4-242, 4-243, 4-244, 4-280, 

4-281, 4-282, 4-283, 4-311, 4-312, 4-313, 4-332, 4-333, 4-357, 4-358, 4-359, 4-380, 4-381, 4-417, 

4-418, 4-419, 4-454, 4-455, 4-456, 4-457, 4-458

Alternative G, xiii, xvii, xxi, xxiv, xxv, xxvi, 2-3, 2-20, 2-21, 2-22, 2-34, 2-35, 2-36, 2-37, 2-38, 4-121, 

4-122, 4-123, 4-124, 4-125, 4-177, 4-178, 4-179, 4-216, 4-217, 4-244, 4-245, 4-282, 4-283, 4-313, 

4-314, 4-334, 4-359, 4-360, 4-381, 4-382, 4-395, 4-396, 4-419, 4-420, 4-459, 4-460, 4-461, 4-462

Archaeological Resources, x, xiii, xv, xx, xxvi, 1-4, 1-5, 1-9, 1-29, 2-4, 2-5, 2-24, 2-33, 2-38, 3-3, 3-5, 

3-7, 3-9, 3-13, 3-29, 3-30, 3-33, 3-50, 4-3, 4-7, 4-45, 4-58, 4-297, 4-298, 4-382, 4-383, 4-385, 

4-386, 4-387, 4-388, 4-389, 4-390, 4-391, 4-392, 4-393, 4-394, 4-395, 4-396, 5-4 

Area of Interest (AOI), viii, ix, xiv, xvi, xvii, xxiv, 1-3, 1-6, 1-27, 1-29, 2-3, 2-9, 2-12, 2-14, 2-16, 2-18, 

2-19, 2-23, 2-32, 2-33, 2-35, 2-36, 2-41, 2-50, 3-4, 3-6, 3-8, 3-11, 3-14, 3-16, 3-20, 3-21, 3-22, 

3-23, 3-25, 3-31, 3-32, 3-34, 3-35, 3-36, 3-37, 3-42, 3-43, 4-5, 4-8, 4-14, 4-18, 4-19, 4-20, 4-23, 

4-24, 4-25, 4-26, 4-42, 4-45, 4-55, 4-57, 4-59, 4-60, 4-61, 4-63, 4-64, 4-65, 4-66, 4-68, 4-69, 4-71, 

4-72, 4-73, 4-74, 4-75, 4-77, 4-78, 4-80, 4-81, 4-82, 4-83, 4-84, 4-86, 4-87, 4-89, 4-90, 4-91, 4-92, 

4-93, 4-94, 4-95, 4-96, 4-97, 4-98, 4-99, 4-100, 4-101, 4-102, 4-103, 4-104, 4-105, 4-106, 4-107, 

4-108, 4-110, 4-111, 4-112, 4-113, 4-115, 4-116, 4-119, 4-120, 4-121, 4-122, 4-124, 4-125, 4-126, 

4-127, 4-129, 4-130, 4-132, 4-135, 4-138, 4-139, 4-140, 4-141, 4-142, 4-143, 4-144, 4-145, 4-146, 

4-147, 4-148, 4-149, 4-150, 4-152, 4-153, 4-154, 4-155, 4-156, 4-159, 4-160, 4-161, 4-162, 4-164, 
Keywords-6 Gulf of Mexico G&G Activities Programmatic EIS

4-165, 4-166, 4-167, 4-168, 4-169, 4-170, 4-171, 4-172, 4-173, 4-174, 4-175, 4-176, 4-177, 4-178, 

4-179, 4-180, 4-181, 4-182, 4-183, 4-185, 4-186, 4-190, 4-191, 4-193, 4-194, 4-195, 4-196, 4-197, 

4-198, 4-199, 4-200, 4-201, 4-203, 4-204, 4-205, 4-206, 4-207, 4-208, 4-209, 4-210, 4-212, 4-213, 

4-214, 4-215, 4-216, 4-217, 4-219, 4-220, 4-221, 4-222, 4-223, 4-227, 4-228, 4-229, 4-230, 4-231, 

4-232, 4-235, 4-236, 4-237, 4-239, 4-245, 4-246, 4-247, 4-249, 4-250, 4-252, 4-253, 4-254, 4-255, 

4-257, 4-258, 4-260, 4-262, 4-263, 4-264, 4-265, 4-266, 4-267, 4-268, 4-270, 4-271, 4-272, 4-274, 

4-277, 4-279, 4-280, 4-281, 4-282, 4-283, 4-284, 4-287, 4-288, 4-289, 4-290, 4-291, 4-293, 4-294, 

4-295, 4-298, 4-300, 4-301, 4-302, 4-304, 4-305, 4-307, 4-308, 4-309, 4-310, 4-311, 4-313, 4-314, 

4-316, 4-318, 4-319, 4-321, 4-322, 4-323, 4-324, 4-332, 4-334, 4-335, 4-336, 4-338, 4-340, 4-341, 

4-342, 4-343, 4-344, 4-345, 4-347, 4-348, 4-349, 4-350, 4-352, 4-353, 4-355, 4-356, 4-358, 4-360, 

4-361, 4-362, 4-363, 4-364, 4-365, 4-366, 4-367, 4-368, 4-369, 4-370, 4-371, 4-372, 4-373, 4-375, 

4-376, 4-378, 4-379, 4-380, 4-382, 4-383, 4-386, 4-387, 4-388, 4-396, 4-397, 4-398, 4-399, 4-400, 

4-401, 4-402, 4-403, 4-404, 4-405, 4-406, 4-407, 4-408, 4-409, 4-410, 4-411, 4-412, 4-414, 4-416, 

4-418, 4-419, 4-420, 4-427, 4-437, 4-439, 4-441, 4-443, 4-446, 4-448, 4-450, 4-455, 4-459, 4-460, 

5-4, 5-5, 6-18

Areas of Concern, xi, xii, 1-11, 1-12, 2-9, 2-10, 2-11, 2-41, 4-92, 4-93, 4-94, 4-96, 4-97, 4-110, 

4-115, 4-163, 4-164, 4-165, 4-205, 4-236, 4-270, 4-271, 4-303, 4-326, 4-349, 4-350, 4-372, 4-411, 

4-438

Attenuation, 4-64, 4-67, 4-80, 4-138, 4-190, 4-224, 4-252, 4-254, 4-255

Beach Nourishment, x, 1-7, 1-30, 2-21, 3-3, 3-10, 3-11, 3-14, 3-39, 3-40, 3-48, 4-3, 4-7, 4-156, 

4-179, 4-217, 4-244, 4-314, 4-395, 4-400, 4-460

Beaches, xv, 2-25, 3-43, 3-48, 4-7, 4-16, 4-126, 4-127, 4-136, 4-137, 4-140, 4-141, 4-146, 4-156, 

4-158, 4-246, 4-247, 4-285, 4-287, 4-288, 4-301, 4-315, 4-324, 4-361, 4-365, 4-420, 4-435

Benthic Communities, x, xi, xiii, xv, xvi, xix, xxiv, 1-29, 2-4, 2-23, 2-24, 2-36, 3-3, 3-5, 3-29, 3-30, 

3-33, 4-3, 4-7, 4-17, 4-40, 4-195, 4-217, 4-218, 4-219, 4-222, 4-223, 4-224, 4-225, 4-226, 4-227, 

4-228, 4-229, 4-230, 4-231, 4-232, 4-233, 4-234, 4-235, 4-236, 4-237, 4-238, 4-239, 4-240, 4-241, 

4-242, 4-243, 4-244, 4-245, 4-268, 4-292, 4-293, 4-294, 4-295, 4-296, 4-297, 4-298, 4-299, 4-301, 

4-341, 4-347, 4-387, 4-389, 5-3 

Benthic Resources, 2-7, 2-9, 2-12, 2-14, 2-15, 2-18, 2-21, 2-22, 4-72, 4-123, 4-152, 4-198, 4-201, 

4-202, 4-226, 4-231, 4-262, 4-300, 4-322, 4-344, 4-351, 4-353, 4-354, 4-357, 4-359, 4-368, 4-389, 

4-452, 4-460

Best Management Practices, xii, 2-8, 2-20, 2-21, 4-71, 4-390, 4-393, 4-428, 4-437, 4-442, 4-446, 

5-3, 6-18

Bow-Riding Dolphins, xii, xxi, 2-15, 2-26, 2-49, 4-106, 4-107, 4-108, 4-111, 4-172, 4-173, 4-211, 

4-240, 4-276, 4-277, 4-308, 4-330, 4-331, 4-354, 4-355, 4-377, 4-378, 4-415

Bycatch, 3-47, 4-70, 4-157

Candidate Species, 4-245, 4-247
Keyword Index Keywords-7 

Central Planning Area (CPA), vii, viii, xi, xiii, xvii, 1-3, 1-6, 2-5, 2-6, 2-17, 2-18, 2-19, 2-33, 2-35, 

2-40, 3-5, 3-6, 3-22, 3-36, 3-37, 3-40, 3-45, 3-46, 3-47, 4-46, 4-47, 4-48, 4-49, 4-50, 4-55, 4-58, 

4-61, 4-62, 4-64, 4-78, 4-80, 4-82, 4-83, 4-86, 4-87, 4-90, 4-113, 4-114, 4-116, 4-117, 4-118, 

4-119, 4-120, 4-125, 4-138, 4-139, 4-141, 4-143, 4-144, 4-152, 4-153, 4-154, 4-155, 4-159, 4-161, 

4-175, 4-177, 4-180, 4-181, 4-200, 4-203, 4-205, 4-207, 4-214, 4-215, 4-218, 4-220, 4-221, 4-243, 

4-265, 4-268, 4-280, 4-281, 4-291, 4-312, 4-332, 4-333, 4-348, 4-350, 4-358, 4-359, 4-364, 4-371, 

4-373, 4-374, 4-380, 4-381, 4-398, 4-400, 4-417, 4-454, 4-455, 4-456, 4-457, 6-3 

Cetaceans

High-Frequency, 2-42, 2-43, 4-32, 4-50, 4-53

Low-Frequency, 2-42, 4-32, 4-54, 4-77, 4-134

Mid-Frequency, 2-42, 2-43, 4-32, 4-50, 4-54

Chemosynthetic Communities, 2-24, 3-29, 3-50, 4-218, 4-219, 4-221, 4-222, 4-227, 4-228, 4-229, 

4-293, 4-296, 5-4 

Clean Air Act (CAA), 1-26, 4-10

Clean Water Act (CWA), 1-26, 4-10, 4-400, 4-431

Climate Change, xvi, 3-36, 3-49, 3-50, 4-75, 4-85, 4-198, 4-203, 4-231, 4-234, 4-235, 4-262, 4-267, 

4-322, 4-324, 4-325, 4-327, 4-329, 4-331, 4-332, 4-333, 4-334, 4-425, 4-435

Coastal Restoration, x, xvi, 1-4, 1-7, 1-29, 1-30, 2-21, 3-3, 3-10, 3-11, 3-14, 3-36, 3-39, 3-40, 3-48, 

4-3, 4-79, 4-80, 4-82, 4-153, 4-155, 4-179, 4-217, 4-233, 4-244, 4-265, 4-314, 4-346, 4-390, 

4-395, 4-399, 4-410, 4-439, 4-444, 4-448, 4-453, 4-457, 4-460, 4-461

Coastal Zone Management, 1-10, 1-26, 4-202, 6-14

Coastal Zone Management Act (CZMA), 1-10, 1-26, 1-28, 4-10, 6-14, 6-15, 6-16

Commercial Fisheries, xiii, xiv, xv, xx, xxv, 2-37, 3-42, 3-43, 4-7, 4-11, 4-14, 4-77, 4-79, 4-81, 4-151, 

4-152, 4-157, 4-158, 4-185, 4-201, 4-221, 4-231, 4-234, 4-235, 4-237, 4-239, 4-240, 4-242, 4-244, 

4-300, 4-301, 4-335, 4-336, 4-337, 4-338, 4-339, 4-340, 4-341, 4-342, 4-343, 4-344, 4-345, 4-346, 

4-347, 4-348, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 4-360, 

4-369, 4-370, 4-390, 4-409, 4-410, 4-412, 4-423, 4-425

Compressed High-Intensity Radiated Pulse (CHIRP), 2-6, 3-12, 3-15, 3-17, 3-18, 3-19, 4-3, 4-4, 

4-24, 4-26, 4-60, 4-62, 4-125, 4-129, 4-132, 4-136, 4-137, 4-141, 4-179, 4-182, 4-189, 4-217, 

4-222, 4-245, 4-249, 4-251, 4-283, 4-289, 4-292, 4-314, 4-336, 4-360, 4-363, 4-382, 5-3 

Conditions of Approval (COAs), xii, 1-10, 2-4, 2-6, 2-7, 2-8, 2-18, 2-20, 2-21, 2-29, 2-31, 4-138, 

4-151, 4-195, 4-297, 4-390, 4-393, 4-428, 4-437, 4-442, 4-446

Cone Penetrometer Test (CPT), 3-6, 3-23, 3-25, 3-30, 4-3, 4-226, 4-385, 4-405
Keywords-8 Gulf of Mexico G&G Activities Programmatic EIS

Continental Offshore Stratigraphic Test (COST) Well, 3-20, 3-21, 3-23, 3-26, 3-29, 3-31, 3-32, 3-33, 

4-66, 4-69, 4-83, 4-90, 4-122, 4-142, 4-143, 4-144, 4-145, 4-146, 4-154, 4-156, 4-162, 4-178, 

4-226, 4-228, 4-254, 4-258, 4-259, 4-260, 4-264, 4-266, 4-270, 4-271, 4-274, 4-302, 4-405

Controlled Source Electromagnetic (CSEM) Survey, 3-23, 3-27, 3-31, 4-227

Council on Environmental Quality (CEQ), 1-8, 1-18, 1-27, 2-3, 2-22, 2-23, 2-24, 3-36, 4-9, 4-18, 

4-421, 6-3, 6-5, 6-13

CPA Closure Area, xiii, xvii, 2-17, 2-19, 2-33, 2-35, 4-113, 4-114, 4-116, 4-117, 4-118, 4-120, 4-125, 

4-175, 4-177, 4-214, 4-215, 4-243, 4-280, 4-281, 4-312, 4-332, 4-333, 4-358, 4-359, 4-380, 4-381, 

4-417, 4-454, 4-455, 4-456, 4-457

Critical Habitat, 1-22, 3-50, 4-126, 4-130, 4-138, 4-140, 4-141, 4-161, 4-180, 4-190, 4-250, 4-316, 

4-320, 5-4, 6-16

Cultural Resources, 3-12, 3-13, 3-14, 3-15, 4-3, 4-283, 4-299, 4-384, 4-386, 4-390, 4-393, 5-4 

Cumulative Impacts, xiv, 1-13, 1-17, 1-28, 1-29, 2-23, 4-9, 4-10, 4-11, 4-15, 4-75, 4-77, 4-84, 4-87, 

4-98, 4-105, 4-106, 4-108, 4-109, 4-112, 4-113, 4-120, 4-121, 4-124, 4-151, 4-152, 4-160, 4-166, 

4-167, 4-171, 4-172, 4-173, 4-174, 4-175, 4-176, 4-177, 4-197, 4-199, 4-200, 4-201, 4-202, 4-203, 

4-207, 4-209, 4-210, 4-211, 4-213, 4-215, 4-216, 4-230, 4-231, 4-235, 4-236, 4-237, 4-238, 4-239, 

4-240, 4-241, 4-242, 4-243, 4-244, 4-245, 4-261, 4-265, 4-268, 4-272, 4-275, 4-277, 4-279, 4-281, 

4-282, 4-283, 4-299, 4-300, 4-301, 4-304, 4-305, 4-307, 4-309, 4-310, 4-311, 4-312, 4-313, 4-314, 

4-321, 4-322, 4-323, 4-324, 4-325, 4-327, 4-329, 4-330, 4-331, 4-332, 4-333, 4-334, 4-343, 4-344, 

4-348, 4-351, 4-353, 4-354, 4-357, 4-359, 4-360, 4-367, 4-370, 4-373, 4-374, 4-376, 4-377, 4-379, 

4-380, 4-381, 4-382, 4-388, 4-390, 4-393, 4-394, 4-395, 4-396, 4-408, 4-409, 4-410, 4-412, 4-413, 

4-414, 4-415, 4-416, 4-417, 4-418, 4-419, 4-429, 4-430, 4-431, 4-432, 4-433, 4-434, 4-440, 4-444, 

4-445, 4-449, 4-453, 4-454, 4-458, 4-462

De Soto Canyon, xi, xii, 2-12, 2-13, 2-14, 2-18, 2-46, 4-19, 4-100, 4-101, 4-103, 4-106, 4-107, 4-111, 

4-114, 4-119, 4-163, 4-290, 4-291

Decibel, 1-12, 1-19, 2-10, 2-17, 2-19, 3-18, 3-19, 3-20, 3-21, 3-26, 4-12, 4-26, 4-27, 4-30, 4-31, 4-32, 

4-34, 4-35, 4-36, 4-37, 4-39, 4-48, 4-49, 4-50, 4-51, 4-52, 4-55, 4-56, 4-59, 4-61, 4-62, 4-63, 4-64, 

4-66, 4-67, 4-69, 4-79, 4-95, 4-131, 4-132, 4-134, 4-136, 4-137, 4-139, 4-142, 4-144, 4-170, 

4-185, 4-186, 4-188, 4-191, 4-192, 4-225, 4-251, 4-254, 4-339

Deep-Penetration Seismic Airgun Survey, x, xvii, xxv, 1-8, 1-11, 1-12, 2-8, 2-9, 2-10, 2-11, 2-12, 

2-13, 2-14, 2-16, 2-17, 2-18, 2-33, 2-34, 2-37, 2-40, 3-3, 3-5, 3-22, 3-24, 4-25, 4-26, 4-45, 4-46, 

4-49, 4-52, 4-55, 4-56, 4-64, 4-69, 4-83, 4-86, 4-88, 4-91, 4-92, 4-93, 4-94, 4-96, 4-97, 4-98, 

4-100, 4-120, 4-125, 4-130, 4-138, 4-143, 4-145, 4-154, 4-159, 4-161, 4-162, 4-163, 4-164, 4-167, 

4-179, 4-189, 4-204, 4-205, 4-207, 4-208, 4-215, 4-236, 4-243, 4-251, 4-252, 4-258, 4-269, 4-270, 

4-271, 4-283, 4-303, 4-325, 4-326, 4-327, 4-348, 4-349, 4-350, 4-352, 4-361, 4-371, 4-372, 4-374, 

4-375, 4-405, 4-411, 4-413
Keyword Index Keywords-9 

Deepwater Horizon, viii, 1-17, 1-18, 3-47, 4-11, 4-15, 4-16, 4-17, 4-22, 4-23, 4-126, 4-128, 4-151, 

4-160, 4-197, 4-218, 4-230, 4-247, 4-248, 4-261, 4-273, 4-275, 4-277, 4-280, 4-282, 4-315, 4-316, 

4-321, 4-336, 4-362, 4-363, 4-368, 4-388, 4-389, 4-408, 6-5, 6-16

Demersal, 4-180, 4-182, 4-186, 4-189, 4-194, 4-196, 4-339, 4-342, 4-358

Discharges, xiv, xvi, 2-25, 3-28, 3-32, 3-33, 3-38, 3-39, 3-40, 4-6, 4-71, 4-76, 4-83, 4-84, 4-147, 

4-158, 4-195, 4-200, 4-201, 4-228, 4-229, 4-232, 4-262, 4-267, 4-296, 4-297, 4-298, 4-302, 4-312, 

4-318, 4-319, 4-322, 4-323, 4-325, 4-326, 4-328, 4-330, 4-387, 4-391, 4-393, 4-394, 4-396

Drilling, xv, xviii, xix, xx, xxvi, 2-24, 2-38, 3-17, 3-32, 3-36, 3-37, 3-38, 3-41, 4-4, 4-83, 4-182, 4-195, 

4-196, 4-200, 4-201, 4-205, 4-206, 4-209, 4-210, 4-212, 4-214, 4-217, 4-222, 4-228, 4-229, 4-230, 

4-232, 4-236, 4-238, 4-239, 4-241, 4-242, 4-243, 4-244, 4-245, 4-289, 4-296, 4-297, 4-298, 4-302, 

4-303, 4-305, 4-306, 4-307, 4-308, 4-309, 4-310, 4-312, 4-313, 4-314, 4-322, 4-383, 4-387, 4-388, 

4-391, 4-393, 4-394, 4-395, 4-396

Vessel, xiv, xv, xvi, xix, 2-24, 3-17, 3-27, 3-36, 3-37, 3-39, 3-42, 3-43, 3-44, 3-45, 3-47, 3-48, 4-4, 

4-6, 4-316, 4-318, 4-319, 4-320, 4-323, 4-325, 4-326, 4-328, 4-330, 4-331, 4-332, 4-334

Distinct Population Segment (DPS), 4-20, 4-126, 4-320

Dolphin

Atlantic Spotted, xvii, xxi, xxiii, 2-35, 4-19, 4-59, 4-63, 4-78, 4-80, 4-88, 4-89, 4-91, 4-94, 4-100, 

4-101, 4-113, 4-116, 4-117, 4-118, 4-125

Bottlenose, xvii, xxi, xxiii, 2-11, 2-13, 2-32, 2-35, 4-19, 4-22, 4-34, 4-44, 4-47, 4-48, 4-50, 4-51, 

4-52, 4-54, 4-55, 4-59, 4-61, 4-62, 4-63, 4-65, 4-68, 4-78, 4-80, 4-85, 4-88, 4-89, 4-91, 4-94, 

4-99, 4-100, 4-101, 4-105, 4-113, 4-116, 4-117, 4-120, 4-125, 4-161, 4-191

Clymene, 1-20, 4-19, 4-50, 4-117

Rough-Toothed, 4-118

Spinner, 4-100, 4-116, 4-117, 4-118

Striped, 4-63, 4-100, 4-116, 4-117, 4-118

Dry Tortugas Closure Area, xiii, 2-17, 2-20, 2-33, 4-113, 4-114, 4-117, 4-118, 4-120, 4-175, 4-177, 

4-214, 4-215, 4-243, 4-280, 4-281, 4-312, 4-313, 4-332, 4-333, 4-358, 4-359, 4-380, 4-381, 4-417

Eastern Planning Area (EPA), vii, viii, xi, xiii, xvii, 1-3, 1-6, 1-11, 1-12, 2-5, 2-9, 2-10, 2-11, 2-13, 

2-17, 2-18, 2-19, 2-33, 2-35, 2-40, 3-5, 3-6, 3-22, 3-36, 3-38, 3-40, 3-46, 4-46, 4-47, 4-48, 4-49, 

4-59, 4-61, 4-62, 4-86, 4-88, 4-90, 4-93, 4-94, 4-97, 4-98, 4-113, 4-114, 4-117, 4-118, 4-119, 

4-120, 4-125, 4-138, 4-139, 4-144, 4-159, 4-161, 4-164, 4-165, 4-166, 4-175, 4-177, 4-180, 4-181, 

4-200, 4-203, 4-205, 4-207, 4-214, 4-215, 4-220, 4-223, 4-236, 4-243, 4-268, 4-270, 4-271, 4-272, 

4-280, 4-281, 4-290, 4-291, 4-295, 4-302, 4-303, 4-312, 4-313, 4-326, 4-327, 4-328, 4-332, 4-333, 

4-348, 4-349, 4-350, 4-358, 4-359, 4-369, 4-371, 4-372, 4-374, 4-380, 4-381, 4-398, 4-400, 4-417, 

4-438, 6-3, 6-5, 6-18
Keywords-10 Gulf of Mexico G&G Activities Programmatic EIS

Echosounder

Multibeam, 3-12, 3-13, 3-17, 3-18, 3-19, 4-3, 4-4, 4-24, 4-26, 4-27, 4-30, 4-42, 4-46, 4-58, 4-60, 

4-61, 4-62, 4-63, 4-125, 4-129, 4-130, 4-132, 4-136, 4-137, 4-141, 4-179, 4-182, 4-189, 4-217, 

4-222, 4-245, 4-249, 4-251, 4-283, 4-289, 4-292, 4-314, 4-336, 4-339, 4-360, 4-363, 4-382, 5-3 

Single-Beam, 3-12, 3-13, 3-15, 3-18, 3-19, 4-3, 4-4, 4-24, 4-26, 4-46, 4-58, 4-60, 4-125, 4-129, 

4-130, 4-141, 4-179, 4-182, 4-217, 4-222, 4-245, 4-249, 4-251, 4-283, 4-289, 4-292, 4-314, 

4-336, 4-360, 4-363, 4-382

Endangered Species Act (ESA), vii, 1-5, 1-7, 1-10, 1-22, 1-25, 1-26, 1-28, 2-6, 2-8, 2-40, 2-50, 4-9, 

4-10, 4-18, 4-20, 4-21, 4-41, 4-53, 4-55, 4-94, 4-126, 4-158, 4-180, 4-214, 4-218, 4-222, 4-245, 

4-247, 6-7, 6-8, 6-14, 6-16

Energy Policy Act (EPAct), 1-3, 1-7, 4-399, 6-14, 6-15

Entanglement, xiv, xv, xvi, xviii, xx, xxiv, xxv, xxvi, 2-24, 2-34, 2-36, 2-37, 2-38, 3-17, 3-33, 3-36, 

3-41, 3-42, 3-43, 4-4, 4-24, 4-70, 4-71, 4-72, 4-73, 4-75, 4-84, 4-86, 4-87, 4-89, 4-92, 4-93, 4-95, 

4-97, 4-101, 4-103, 4-104, 4-106, 4-107, 4-110, 4-111, 4-119, 4-121, 4-124, 4-125, 4-129, 4-133, 

4-138, 4-146, 4-147, 4-148, 4-149, 4-151, 4-156, 4-159, 4-160, 4-161, 4-162, 4-163, 4-164, 4-165, 

4-166, 4-168, 4-169, 4-170, 4-171, 4-172, 4-174, 4-175, 4-176, 4-177, 4-178, 4-179, 4-182, 4-194, 

4-195, 4-196, 4-198, 4-200, 4-202, 4-205, 4-206, 4-209, 4-210, 4-212, 4-213, 4-214, 4-216, 4-217, 

4-226, 4-249, 4-253, 4-256, 4-259, 4-265, 4-278, 4-283, 4-301, 4-320, 4-336, 4-342, 4-343, 4-344, 

4-347, 4-348, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 4-360, 

4-361, 4-383, 4-385, 4-387, 4-388, 4-389, 4-393, 4-396

Environmental Justice, xxi, xxvi, 1-26, 2-38, 4-420, 4-421, 4-422, 4-427, 4-430, 4-437, 4-440, 4-441, 

4-445, 4-446, 4-449, 4-450, 4-454, 4-455, 4-458, 4-459, 4-462

EPA Closure Area, xiii, xvii, 2-17, 2-19, 2-33, 2-35, 4-113, 4-114, 4-117, 4-118, 4-120, 4-125, 4-175, 

4-177, 4-214, 4-215, 4-243, 4-280, 4-281, 4-312, 4-313, 4-332, 4-333, 4-358, 4-359, 4-380, 4-381, 

4-417

Essential Fish Habitat (EFH), xiii, xv, xviii, xxiv, 2-24, 2-36, 4-7, 4-179, 4-180, 4-181, 4-182, 4-183, 

4-190, 4-193, 4-194, 4-195, 4-196, 4-197, 4-198, 4-199, 4-200, 4-201, 4-202, 4-203, 4-204, 4-205, 

4-206, 4-207, 4-208, 4-209, 4-210, 4-211, 4-212, 4-213, 4-214, 4-215, 4-216, 4-217, 4-219, 4-292, 

4-293, 4-294, 4-297, 4-298, 4-299, 4-304, 4-307, 4-308, 4-310, 4-312, 4-344, 5-3, 6-7, 6-16

Exclusion Zone, xii, 1-11, 2-5, 2-17, 2-26, 2-39, 2-42, 2-43, 2-44, 2-45, 2-46, 2-47, 2-48, 2-49, 3-27, 

4-30, 4-33, 4-39, 4-57, 4-60, 4-90, 4-91, 4-92, 4-95, 4-100, 4-101, 4-102, 4-106, 4-138, 4-139, 

4-162, 4-163, 4-168, 4-169, 4-292, 4-349, 4-370, 4-375, 4-415, 4-425, 5-3, 5-5 

Exclusive Economic Zone (EEZ), 2-20, 3-37, 4-77, 4-114, 4-336, 4-362, 6-3 

Exploration and Development, x, xvi, 1-5, 1-9, 1-18, 1-29, 2-34, 2-50, 3-3, 3-32, 3-35, 3-37, 3-38, 

4-14, 4-45, 4-77, 4-78, 4-81, 4-83, 4-145, 4-228, 4-232, 4-266, 4-347, 4-369, 4-412, 4-430, 4-439, 

4-443, 4-448, 4-452, 4-457, 6-15
Keyword Index Keywords-11

Fish Resources, xxiv, 2-36, 4-179, 4-182, 4-183, 4-185, 4-190, 4-191, 4-193, 4-194, 4-195, 4-196, 

4-197, 4-198, 4-199, 4-200, 4-201, 4-202, 4-203, 4-204, 4-205, 4-206, 4-207, 4-208, 4-209, 4-210, 

4-211, 4-212, 4-213, 4-214, 4-215, 4-216, 4-217, 4-299, 4-304, 4-307, 4-308, 4-310, 4-312, 4-337, 

4-355, 4-364, 4-368, 4-378

Fisheries, vii, xiii, xv, xviii, xxiv, xxvi, 1-4, 1-5, 1-17, 2-29, 2-37, 2-44, 3-27, 3-47, 4-7, 4-15, 4-17, 

4-40, 4-70, 4-85, 4-128, 4-157, 4-180, 4-181, 4-194, 4-197, 4-198, 4-202, 4-221, 4-284, 4-286, 

4-289, 4-292, 4-293, 4-294, 4-295, 4-297, 4-298, 4-299, 4-300, 4-302, 4-303, 4-305, 4-311, 4-335, 

4-336, 4-337, 4-338, 4-339, 4-340, 4-341, 4-342, 4-343, 4-344, 4-345, 4-346, 4-347, 4-349, 4-350, 

4-351, 4-352, 4-353, 4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 4-360, 4-363, 4-364, 4-366, 4-367, 

4-369, 4-371, 4-372, 4-373, 4-375, 4-376, 4-377, 4-378, 4-379, 4-380, 4-381, 4-382, 4-390, 4-425, 

6-5, 6-7, 6-8, 6-9, 6-10, 6-16

Fishes, xxiv, 2-20, 2-23, 2-24, 2-33, 2-36, 4-40, 4-41, 4-53, 4-94, 4-113, 4-133, 4-134, 4-142, 4-180, 

4-181, 4-182, 4-183, 4-184, 4-185, 4-186, 4-189, 4-191, 4-192, 4-194, 4-196, 4-197, 4-198, 4-199, 

4-200, 4-202, 4-203, 4-217, 4-220, 4-285, 4-286, 4-289, 4-293, 4-294, 4-295, 4-296, 4-299, 4-316, 

4-338, 4-339, 4-343, 4-345, 4-347, 4-361, 4-364, 4-365, 4-366, 5-3 

Flower Gardens Closure Area, 2-20, 2-33, 4-113, 4-118, 4-120, 4-175, 4-177, 4-214, 4-215, 4-243, 

4-280, 4-281, 4-312, 4-313, 4-332, 4-333, 4-358, 4-359, 4-380, 4-381, 4-417

Geological and Geophysical (G&G) Activities, vii, viii, ix, x, xii, xiii, xiv, xv, xvi, xxiv, xxvi, 1-3, 1-4, 1-5, 

1-6, 1-7, 1-8, 1-9, 1-10, 1-16, 1-28, 1-29, 2-3, 2-5, 2-7, 2-8, 2-9, 2-11, 2-13, 2-15, 2-17, 2-20, 2-21, 

2-22, 2-23, 2-24, 2-25, 2-26, 2-28, 2-34, 2-36, 2-37, 2-38, 2-39, 2-40, 2-46, 2-50, 3-1, 3-3, 3-4, 3-5, 

3-8, 3-9, 3-12, 3-13, 3-14, 3-15, 3-17, 3-19, 3-20, 3-22, 3-23, 3-26, 3-29, 3-33, 3-34, 3-35, 3-36, 

3-37, 3-38, 3-39, 3-40, 3-41, 3-42, 3-43, 3-44, 3-45, 3-47, 3-48, 4-3, 4-4, 4-5, 4-6, 4-7, 4-8, 4-9, 

4-10, 4-12, 4-18, 4-29, 4-33, 4-45, 4-56, 4-64, 4-70, 4-71, 4-74, 4-75, 4-77, 4-81, 4-83, 4-84, 4-85, 

4-88, 4-96, 4-98, 4-103, 4-107, 4-110, 4-121, 4-122, 4-123, 4-124, 4-138, 4-147, 4-150, 4-152, 

4-154, 4-155, 4-160, 4-167, 4-172, 4-173, 4-175, 4-177, 4-178, 4-179, 4-182, 4-187, 4-191, 4-193, 

4-194, 4-195, 4-198, 4-199, 4-200, 4-208, 4-210, 4-211, 4-213, 4-214, 4-215, 4-216, 4-217, 4-223, 

4-225, 4-226, 4-227, 4-228, 4-231, 4-244, 4-245, 4-246, 4-247, 4-250, 4-251, 4-254, 4-255, 4-257, 

4-262, 4-263, 4-264, 4-266, 4-269, 4-273, 4-276, 4-281, 4-282, 4-290, 4-291, 4-294, 4-295, 4-296, 

4-297, 4-298, 4-300, 4-301, 4-303, 4-304, 4-306, 4-308, 4-310, 4-312, 4-313, 4-314, 4-322, 4-323, 

4-325, 4-328, 4-330, 4-332, 4-334, 4-338, 4-339, 4-340, 4-341, 4-342, 4-343, 4-345, 4-346, 4-347, 

4-348, 4-351, 4-353, 4-354, 4-357, 4-358, 4-359, 4-360, 4-361, 4-366, 4-367, 4-368, 4-371, 4-375, 

4-380, 4-381, 4-382, 4-383, 4-386, 4-387, 4-389, 4-393, 4-395, 4-402, 4-403, 4-404, 4-405, 4-406, 

4-407, 4-408, 4-409, 4-410, 4-411, 4-412, 4-413, 4-414, 4-415, 4-416, 4-418, 4-419, 4-420, 4-421, 

4-425, 4-426, 4-427, 4-428, 4-429, 4-430, 4-436, 4-437, 4-438, 4-439, 4-440, 4-441, 4-442, 4-444, 

4-445, 4-446, 4-447, 4-448, 4-449, 4-450, 4-453, 4-454, 4-455, 4-458, 4-460, 4-461, 4-462, 5-4, 

6-3, 6-5, 6-6, 6-7, 6-8, 6-12, 6-15, 6-16, 6-18, 6-19

Geological Sampling, 1-8, 2-21, 3-12, 3-13, 3-14, 4-3 

Geotechnical Sampling, 2-5, 3-5, 3-13, 3-14, 3-20, 3-25, 5-3 

Gulf of Mexico Energy Security Act (GOMESA), 3-5, 4-14, 4-400
Keywords-12 Gulf of Mexico G&G Activities Programmatic EIS

Habitat Area of Particular Concern (HAPC), 2-24, 3-29, 4-285, 4-286, 4-290, 4-291, 4-294, 4-297

Harassment, 1-4, 1-22, 2-17, 2-26, 2-38, 2-43, 4-12, 4-21, 4-53, 4-54, 4-56, 4-65, 4-95, 4-122, 

4-129, 4-130, 4-158

Hard Bottom, 4-180, 4-181, 4-186, 4-189, 4-194, 4-218, 4-219, 4-220, 4-221, 4-227, 4-361

Artificial Reefs, 3-39, 4-181, 4-221, 4-285, 4-342, 4-346, 4-388, 4-392

Deepwater Coral Communities, 3-29, 4-218, 4-219, 4-227, 4-229

Live Bottom, 2-24, 3-29, 4-220, 4-221, 4-226, 4-227, 4-228, 4-229, 4-234, 4-293, 4-296, 4-342, 5-3 

Topographic Features, 3-29, 4-220, 4-227, 4-284

High-Resolution Geophysical (HRG) Survey, xi, xii, xvii, xxiv, 1-8, 1-29, 2-11, 2-18, 2-21, 2-35, 2-36, 

2-44, 2-48, 3-3, 3-5, 3-6, 3-9, 3-17, 3-18, 3-23, 3-24, 3-25, 4-25, 4-26, 4-40, 4-42, 4-45, 4-58, 4-60, 

4-61, 4-63, 4-65, 4-86, 4-89, 4-100, 4-102, 4-103, 4-104, 4-107, 4-111, 4-118, 4-119, 4-125, 

4-130, 4-131, 4-141, 4-142, 4-143, 4-152, 4-159, 4-163, 4-164, 4-165, 4-166, 4-168, 4-169, 4-170, 

4-172, 4-174, 4-176, 4-177, 4-179, 4-189, 4-191, 4-192, 4-198, 4-204, 4-206, 4-208, 4-210, 4-212, 

4-214, 4-215, 4-224, 4-225, 4-231, 4-251, 4-252, 4-253, 4-260, 4-262, 4-268, 4-271, 4-273, 4-274, 

4-276, 4-278, 4-279, 4-292, 4-293, 4-300, 4-306, 4-311, 4-322, 4-328, 4-337, 4-339, 4-344, 4-349, 

4-350, 4-351, 4-352, 4-353, 4-354, 4-356, 4-357, 4-358, 4-359, 4-364, 4-365, 4-366, 4-368, 4-372, 

4-373, 4-375, 4-383, 4-389, 4-402, 4-403, 4-404, 4-439, 4-443, 4-444, 4-447, 4-448, 4-453, 4-457, 

5-3 

Impact-Producing Factor (IPF), viii, xiv, xv, xvi, xvii, xviii, xix, xx, xxi, xxii, xxiv, xxv, xxvi, 2-23, 2-32, 

2-33, 2-34, 2-35, 2-36, 2-37, 2-38, 3-16, 3-17, 3-23, 3-34, 3-35, 3-36, 3-37, 3-38, 3-39, 3-40, 3-41, 

3-42, 3-43, 3-44, 3-45, 3-47, 3-48, 4-4, 4-5, 4-8, 4-9, 4-10, 4-15, 4-24, 4-67, 4-69, 4-72, 4-73, 4-75, 

4-86, 4-87, 4-88, 4-89, 4-92, 4-93, 4-94, 4-95, 4-96, 4-97, 4-98, 4-99, 4-100, 4-102, 4-103, 4-104, 

4-105, 4-106, 4-107, 4-108, 4-109, 4-110, 4-111, 4-112, 4-113, 4-115, 4-119, 4-120, 4-121, 4-123, 

4-124, 4-125, 4-129, 4-138, 4-148, 4-149, 4-151, 4-155, 4-158, 4-159, 4-160, 4-161, 4-163, 4-165, 

4-166, 4-167, 4-168, 4-169, 4-170, 4-171, 4-172, 4-173, 4-174, 4-175, 4-176, 4-177, 4-178, 4-179, 

4-181, 4-182, 4-183, 4-196, 4-197, 4-201, 4-203, 4-204, 4-205, 4-206, 4-207, 4-208, 4-209, 4-210, 

4-211, 4-212, 4-213, 4-214, 4-215, 4-216, 4-217, 4-218, 4-222, 4-223, 4-230, 4-233, 4-235, 4-237, 

4-239, 4-240, 4-241, 4-242, 4-243, 4-244, 4-245, 4-249, 4-251, 4-261, 4-262, 4-268, 4-269, 4-272, 

4-273, 4-275, 4-276, 4-277, 4-278, 4-279, 4-280, 4-281, 4-282, 4-283, 4-289, 4-290, 4-299, 4-302, 

4-303, 4-304, 4-305, 4-306, 4-307, 4-308, 4-309, 4-310, 4-311, 4-312, 4-313, 4-314, 4-316, 4-317, 

4-320, 4-322, 4-325, 4-326, 4-327, 4-328, 4-329, 4-330, 4-331, 4-332, 4-333, 4-334, 4-336, 4-337, 

4-344, 4-348, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 4-360, 

4-363, 4-367, 4-371, 4-372, 4-373, 4-374, 4-375, 4-376, 4-377, 4-378, 4-379, 4-380, 4-381, 4-382, 

4-383, 4-384, 4-387, 4-388, 4-393, 4-395, 4-396, 4-401, 4-408, 4-409, 4-411, 4-413, 4-415, 4-416, 

4-417, 4-418, 4-419, 4-425, 4-430, 4-433, 4-440, 4-445, 4-449, 4-454, 4-458, 4-462

Incidental Take, xiii, 1-4, 1-5, 1-7, 1-9, 1-10, 1-14, 1-16, 1-22, 1-28, 2-21, 2-22, 4-53, 6-7, 6-8 

Incidental Take Regulations, 4-53
Keyword Index Keywords-13

Infrastructure, xvi, xxi, xxvi, 1-6, 2-21, 2-38, 3-10, 3-13, 3-35, 3-37, 3-38, 3-40, 3-41, 3-45, 3-49, 4-5, 

4-198, 4-221, 4-233, 4-235, 4-300, 4-399, 4-400, 4-404, 4-405, 4-407, 4-410, 4-412, 4-414, 4-420, 

4-421, 4-425, 4-426, 4-427, 4-429, 4-430, 4-431, 4-432, 4-433, 4-434, 4-436, 4-437, 4-439, 4-440, 

4-441, 4-442, 4-444, 4-445, 4-447, 4-448, 4-449, 4-450, 4-453, 4-454, 4-455, 4-457, 4-458, 4-459, 

4-461, 4-462

International Convention for the Prevention of Pollution from Ships (MARPOL), 2-25, 4-6, 4-71, 4-84, 

4-147, 4-156, 4-193, 4-226, 4-232, 4-259, 4-266, 4-296, 4-301, 4-319, 4-324

Levee Reconstruction, 3-39, 3-40

Level A Harassment, 2-6, 2-13, 2-15, 2-17, 2-19, 2-26, 4-21, 4-55, 4-109, 5-3 

Level B Harassment, 2-17, 2-19, 4-21, 4-56, 4-64, 4-86, 4-91, 4-101, 4-109, 5-3 

Louisiana Offshore Oil Port (LOOP), 3-42, 4-400

Magnuson-Stevens Fishery Conservation and Management Act (MSFCMA), 1-5, 1-10, 1-26, 1-28, 

4-10, 6-7, 6-8, 6-14, 6-16

Manatee, xi, xvii, xxi, xxiii, 1-11, 2-9, 2-12, 2-13, 2-15, 2-16, 2-18, 2-33, 2-35, 2-49, 4-18, 4-19, 4-20, 

4-28, 4-78, 4-81, 4-88, 4-89, 4-90, 4-91, 4-92, 4-94, 4-96, 4-100, 4-101, 4-102, 4-103, 4-107, 

4-110, 4-119, 4-125, 4-162, 4-168, 4-169, 4-175, 4-204, 4-208, 4-269, 4-273, 4-285, 4-288, 4-289, 

4-303, 4-306, 4-325, 4-328, 4-348, 4-351, 4-371, 4-375, 6-11

Marine and Coastal Birds, xiii, xv, xix, xxv, 2-23, 2-24, 2-36, 4-7, 4-245, 4-247, 4-249, 4-250, 4-253, 

4-255, 4-256, 4-257, 4-258, 4-259, 4-260, 4-261, 4-262, 4-263, 4-264, 4-265, 4-266, 4-268, 4-269, 

4-270, 4-271, 4-272, 4-273, 4-274, 4-275, 4-276, 4-277, 4-278, 4-279, 4-280, 4-281, 4-282, 4-283, 

4-292, 4-294, 4-298, 4-299, 4-304, 4-307, 4-308, 4-310, 4-312, 5-3 

Marine Debris, xi, 2-7, 2-9, 2-12, 2-14, 2-15, 2-18, 2-22, 3-28, 4-70, 4-72, 4-75, 4-84, 4-123, 4-193, 

4-200, 4-226, 4-232, 4-259, 4-266, 4-296, 4-301, 4-319

Marine Mammal Protection Act (MMPA), vii, ix, x, xiii, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-13, 1-16, 

1-20, 1-22, 1-23, 1-25, 1-26, 1-28, 2-6, 2-7, 2-8, 2-9, 2-21, 2-28, 2-40, 2-50, 3-7, 4-10, 4-12, 4-18, 

4-20, 4-21, 4-22, 4-41, 4-43, 4-53, 4-56, 4-80, 4-428, 6-7, 6-8 

Marine Mammals, vii, x, xi, xii, xiii, xv, xvii, xviii, xxi, xxii, xxiii, 1-4, 1-5, 1-7, 1-8, 1-9, 1-10, 1-11, 1-13, 

1-14, 1-15, 1-16, 1-18, 1-19, 1-20, 1-21, 1-22, 1-23, 1-24, 1-25, 1-26, 2-3, 2-4, 2-6, 2-7, 2-8, 2-9, 

2-10, 2-11, 2-12, 2-13, 2-14, 2-15, 2-16, 2-17, 2-18, 2-19, 2-20, 2-22, 2-23, 2-24, 2-26, 2-30, 2-31, 

2-32, 2-33, 2-34, 2-38, 2-40, 2-41, 2-42, 2-43, 2-44, 2-45, 2-46, 2-47, 2-48, 2-49, 2-50, 3-17, 3-18, 

3-33, 3-47, 4-7, 4-9, 4-10, 4-11, 4-12, 4-13, 4-14, 4-16, 4-17, 4-18, 4-19, 4-20, 4-21, 4-22, 4-23, 

4-24, 4-25, 4-26, 4-27, 4-28, 4-29, 4-30, 4-31, 4-32, 4-33, 4-34, 4-35, 4-36, 4-37, 4-39, 4-40, 4-41, 

4-42, 4-44, 4-45, 4-49, 4-52, 4-53, 4-54, 4-55, 4-56, 4-57, 4-58, 4-59, 4-60, 4-61, 4-63, 4-64, 4-65, 

4-66, 4-67, 4-68, 4-69, 4-70, 4-71, 4-72, 4-73, 4-74, 4-75, 4-76, 4-77, 4-78, 4-79, 4-80, 4-81, 4-82, 

4-83, 4-84, 4-85, 4-86, 4-87, 4-88, 4-89, 4-90, 4-91, 4-92, 4-93, 4-94, 4-95, 4-96, 4-97, 4-98, 4-99, 

4-100, 4-101, 4-102, 4-103, 4-104, 4-105, 4-106, 4-107, 4-108, 4-109, 4-110, 4-111, 4-112, 4-113, 

4-114, 4-115, 4-119, 4-120, 4-121, 4-122, 4-123, 4-124, 4-125, 4-126, 4-133, 4-134, 4-139, 4-142, 
Keywords-14 Gulf of Mexico G&G Activities Programmatic EIS

4-162, 4-163, 4-169, 4-170, 4-172, 4-173, 4-180, 4-204, 4-205, 4-208, 4-210, 4-211, 4-214, 4-239, 

4-240, 4-275, 4-276, 4-277, 4-287, 4-292, 4-294, 4-295, 4-297, 4-298, 4-299, 4-302, 4-303, 4-304, 

4-306, 4-307, 4-308, 4-309, 4-310, 4-311, 4-312, 4-329, 4-330, 4-331, 4-348, 4-350, 4-352, 4-353, 

4-354, 4-355, 4-358, 4-371, 4-372, 4-375, 4-377, 4-378, 4-415, 4-445, 4-447, 4-451, 4-456, 5-3, 

6-5, 6-7, 6-8, 6-14

Marine Minerals Program, vii, 1-3, 1-5, 1-6, 1-8, 2-5, 2-7, 3-10, 3-11, 3-12, 3-13, 3-14, 3-19, 3-30, 

3-40, 4-4, 4-81, 4-110, 4-201, 4-251, 4-301, 4-385, 4-399, 4-425, 6-6 

Marine Protected Area, vii, xiii, xv, xix, xxv, 1-26, 2-23, 2-24, 2-33, 2-37, 3-29, 4-7, 4-283, 4-284, 

4-286, 4-287, 4-289, 4-290, 4-291, 4-294, 4-295, 4-296, 4-297, 4-298, 4-299, 4-300, 4-301, 4-302, 

4-303, 4-304, 4-305, 4-306, 4-307, 4-308, 4-309, 4-310, 4-311, 4-312, 4-313, 4-314

Florida Keys National Marine Sanctuary (FGBNMS), 4-284

Flower Garden Banks National Marine Sanctuary (FGBNMS), 2-20, 2-33, 4-54, 4-113, 4-242, 4-284, 

4-285, 4-290, 4-291, 4-293, 4-294, 4-297, 4-302, 4-305, 4-311

National Estuarine Research Reserve (NERR), 4-287, 4-288

National Marine Sanctuary (NMS), xi, 1-5, 1-26, 2-4, 2-7, 2-9, 2-12, 2-14, 2-16, 2-18, 2-20, 2-22, 

4-72, 4-123, 4-284, 4-285, 4-291, 4-292, 4-293, 4-294, 4-295, 4-296, 4-297, 4-299, 4-300, 4-306, 

6-7, 6-8, 6-18

National Seashore, 4-140, 4-287, 4-288

Masking/Auditory Masking, 4-28, 4-33, 4-34, 4-35, 4-40, 4-41, 4-60, 4-63, 4-66, 4-77, 4-78, 4-102, 

4-122, 4-133, 4-135, 4-136, 4-142, 4-143, 4-153, 4-185, 4-186, 4-187, 4-189, 4-190, 4-192, 4-199, 

4-200, 4-225, 4-242, 4-292, 4-293, 4-311, 4-338, 4-364

Memorandum of Agreement (MOA), vii, 1-9, 6-5, 6-7, 6-8 

Memorandum of Understanding (MOU), 1-9 

Mississippi Canyon, xi, 2-12, 2-13, 2-14, 2-16, 2-18, 2-19, 2-46, 4-19, 4-42, 4-55, 4-101, 4-103, 

4-106, 4-107, 4-111, 4-114, 4-119

Mitigation Measure, vii, viii, x, xi, xii, xiii, xvii, xxi, xxii, 1-7, 1-10, 1-12, 1-13, 1-23, 1-28, 1-29, 2-3, 

2-4, 2-5, 2-6, 2-7, 2-8, 2-9, 2-10, 2-11, 2-12, 2-13, 2-15, 2-16, 2-17, 2-19, 2-20, 2-22, 2-29, 2-30, 

2-31, 2-32, 2-33, 2-34, 2-38, 2-40, 2-41, 2-45, 2-46, 2-47, 2-48, 2-49, 2-50, 4-13, 4-24, 4-44, 4-57, 

4-60, 4-66, 4-72, 4-73, 4-75, 4-79, 4-88, 4-89, 4-90, 4-91, 4-92, 4-93, 4-94, 4-95, 4-96, 4-97, 4-98, 

4-99, 4-100, 4-101, 4-102, 4-103, 4-104, 4-105, 4-106, 4-107, 4-108, 4-109, 4-110, 4-111, 4-112, 

4-113, 4-118, 4-119, 4-120, 4-121, 4-123, 4-124, 4-125, 4-129, 4-138, 4-139, 4-141, 4-142, 4-148, 

4-149, 4-151, 4-156, 4-160, 4-162, 4-163, 4-164, 4-165, 4-166, 4-167, 4-168, 4-169, 4-170, 4-171, 

4-172, 4-173, 4-175, 4-176, 4-177, 4-178, 4-182, 4-196, 4-197, 4-204, 4-205, 4-206, 4-207, 4-208, 

4-209, 4-210, 4-211, 4-213, 4-214, 4-215, 4-217, 4-223, 4-235, 4-236, 4-237, 4-238, 4-239, 4-240, 

4-241, 4-242, 4-243, 4-244, 4-249, 4-269, 4-270, 4-272, 4-273, 4-275, 4-276, 4-277, 4-279, 4-280, 

4-281, 4-283, 4-290, 4-291, 4-292, 4-300, 4-302, 4-303, 4-304, 4-305, 4-306, 4-307, 4-308, 4-309, 

4-310, 4-311, 4-312, 4-313, 4-314, 4-317, 4-325, 4-327, 4-328, 4-329, 4-330, 4-331, 4-332, 4-333, 
Keyword Index Keywords-15

4-334, 4-336, 4-348, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 

4-360, 4-363, 4-365, 4-371, 4-372, 4-373, 4-374, 4-375, 4-376, 4-377, 4-378, 4-379, 4-380, 4-381, 

4-382, 4-384, 4-387, 4-393, 4-394, 4-395, 4-399, 4-410, 4-411, 4-412, 4-413, 4-414, 4-415, 4-416, 

4-417, 4-418, 4-419, 4-428, 4-429, 4-441, 4-442, 4-447, 4-449, 4-455, 5-3, 5-4, 5-5, 6-5, 6-16, 

6-18

National Environmental Protection Act (NEPA), vii, viii, xii, 1-5, 1-7, 1-8, 1-10, 1-13, 1-18, 1-22, 1-24, 

1-25, 1-26, 1-27, 1-28, 1-29, 2-8, 2-11, 2-29, 2-32, 2-50, 3-4, 3-11, 3-38, 4-8, 4-10, 4-11, 4-14, 

4-17, 4-23, 4-54, 4-58, 4-93, 4-421, 5-1, 5-3, 5-4, 5-5, 6-3, 6-7, 6-8, 6-14, 6-16, 6-17, 6-18

National Historic Preservation Act (NHPA), 1-5, 1-10, 1-26, 1-28, 4-384, 6-17

National Marine Sanctuaries Act (NMSA), 1-5, 1-10, 1-26, 1-28, 4-292, 4-297, 6-7, 6-8, 6-18

National Park Service (NPS), 4-17, 4-287, 4-382, 6-8 

National Research Council (NRC), 1-23, 3-20, 3-32, 3-33, 3-49, 3-50, 4-9, 4-12, 4-28, 4-36, 4-37, 

4-56, 4-64, 4-76, 4-158, 4-202, 4-228, 4-229, 4-234

National Resources Defense Council (NRDC), 1-10, 2-27

National Wildlife Refuge (NWR), 4-253, 4-259, 4-278, 4-287, 4-288

Noise, xvii, xxiv, 1-12, 1-13, 1-17, 1-22, 1-24, 1-25, 2-10, 2-23, 2-24, 2-26, 2-27, 2-35, 2-36, 2-39, 

2-40, 2-41, 2-46, 2-47, 2-49, 3-6, 3-20, 3-21, 3-26, 3-38, 3-39, 3-40, 4-12, 4-14, 4-23, 4-27, 4-28, 

4-29, 4-30, 4-31, 4-32, 4-33, 4-34, 4-35, 4-36, 4-37, 4-38, 4-39, 4-40, 4-41, 4-52, 4-53, 4-54, 4-55, 

4-56, 4-57, 4-59, 4-60, 4-63, 4-64, 4-65, 4-66, 4-67, 4-69, 4-70, 4-73, 4-75, 4-76, 4-77, 4-78, 4-79, 

4-80, 4-81, 4-82, 4-85, 4-86, 4-88, 4-89, 4-90, 4-91, 4-92, 4-93, 4-95, 4-97, 4-101, 4-102, 4-104, 

4-107, 4-111, 4-114, 4-119, 4-121, 4-122, 4-123, 4-125, 4-131, 4-132, 4-133, 4-135, 4-138, 4-139, 

4-141, 4-142, 4-143, 4-144, 4-146, 4-149, 4-151, 4-152, 4-153, 4-154, 4-155, 4-159, 4-160, 4-161, 

4-162, 4-163, 4-165, 4-170, 4-174, 4-176, 4-178, 4-183, 4-185, 4-187, 4-189, 4-190, 4-191, 4-192, 

4-193, 4-196, 4-198, 4-199, 4-200, 4-204, 4-205, 4-206, 4-209, 4-210, 4-212, 4-214, 4-216, 4-217, 

4-224, 4-231, 4-232, 4-235, 4-246, 4-249, 4-250, 4-251, 4-252, 4-253, 4-254, 4-255, 4-256, 4-257, 

4-258, 4-259, 4-262, 4-263, 4-264, 4-265, 4-267, 4-269, 4-270, 4-271, 4-273, 4-276, 4-278, 4-291, 

4-292, 4-293, 4-294, 4-295, 4-298, 4-299, 4-300, 4-302, 4-307, 4-309, 4-344, 4-345, 4-348, 4-364, 

4-368, 4-369, 4-371, 4-425, 4-432, 4-459, 6-5 

Vessel and Equipment, xiv, xv, xvi, xvii, xviii, xix, xxiv, xxv, 2-33, 2-35, 2-36, 3-17, 3-20, 3-36, 3-37, 

3-41, 3-42, 3-43, 3-44, 3-45, 3-47, 3-48, 4-4, 4-24, 4-64, 4-65, 4-66, 4-73, 4-77, 4-78, 4-86, 4-89, 

4-92, 4-93, 4-97, 4-103, 4-104, 4-106, 4-107, 4-110, 4-111, 4-112, 4-119, 4-122, 4-123, 4-125, 

4-129, 4-142, 4-143, 4-149, 4-152, 4-153, 4-154, 4-159, 4-161, 4-162, 4-163, 4-164, 4-165, 4-168, 

4-169, 4-170, 4-172, 4-174, 4-175, 4-176, 4-178, 4-179, 4-182, 4-192, 4-193, 4-196, 4-198, 4-199, 

4-200, 4-203, 4-204, 4-205, 4-206, 4-208, 4-212, 4-213, 4-214, 4-217, 4-231, 4-241, 4-249, 4-253, 

4-254, 4-255, 4-257, 4-260, 4-263, 4-264, 4-268, 4-269, 4-270, 4-271, 4-273, 4-274, 4-276, 4-278, 

4-279, 4-280, 4-282, 4-283, 4-310, 4-369

Non-Airgun HRG Survey Protocol, xi, 2-12, 2-13, 2-14, 2-15, 2-16, 2-17, 2-18, 4-100, 4-102, 4-104, 

4-107, 4-111, 4-118, 4-119, 4-169, 4-170, 4-306
Keywords-16 Gulf of Mexico G&G Activities Programmatic EIS

Notice of Intent (NOI), 1-9, 1-10, 6-3, 6-5, 6-17

Notice to Lessees and Operators (NTL), xii, 1-11, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9, 2-12, 2-14, 2-15, 2-16, 

2-18, 2-20, 2-22, 2-29, 2-33, 2-39, 2-40, 2-44, 2-45, 2-47, 2-49, 2-50, 3-4, 3-13, 3-29, 4-66, 4-68, 

4-71, 4-145, 4-147, 4-151, 4-156, 4-193, 4-200, 4-204, 4-208, 4-220, 4-226, 4-227, 4-232, 4-259, 

4-266, 4-269, 4-273, 4-296, 4-301, 4-302, 4-306, 4-318, 4-319, 4-324, 4-325, 4-328, 4-348, 4-351, 

4-371, 4-375, 4-393, 4-398, 4-399, 4-403, 4-406, 4-428, 4-437, 4-442, 4-446, 6-15

Ocean Dredged Material Disposal Site (ODMDS), xvi, 3-44, 3-45, 4-399, 4-404, 4-406, 4-407, 4-412, 

4-414, 4-416

Outer Continental Shelf Lands Act (OCSLA), 1-3, 1-5, 1-7, 1-10, 1-26, 1-28, 2-21, 2-34, 2-50, 3-10, 

3-40, 4-149, 4-404, 4-408, 5-4, 6-6, 6-8, 6-14

Passive Acoustic Monitoring (PAM), xi, xii, xiii, 1-12, 2-6, 2-8, 2-9, 2-11, 2-12, 2-13, 2-14, 2-16, 2-18, 

2-22, 2-33, 2-45, 2-46, 2-47, 4-90, 4-91, 4-95, 4-96, 4-99, 4-101, 4-102, 4-103, 4-106, 4-107, 

4-111, 4-119, 4-168, 4-175, 4-204, 4-208, 4-236, 4-237, 4-269, 4-273, 4-302, 4-303, 4-304, 4-306, 

4-325, 4-328, 4-348, 4-351, 4-371, 4-375, 4-428, 4-438, 4-442, 4-447, 4-451, 4-453, 4-455, 4-457, 

6-5 

Physical Oceanography, xv, 2-25, 4-6 

Pinniped, 4-36, 4-70

Planning Area, vii, viii, x, xi, 1-3, 1-5, 2-15, 2-45, 3-3, 3-6, 3-8, 3-19, 3-21, 3-22, 3-26, 3-27, 3-29, 

3-30, 3-31, 3-32, 3-36, 3-37, 3-46, 4-49, 4-54, 4-58, 4-61, 4-86, 4-87, 4-110, 4-181, 4-220, 4-223, 

4-225, 4-227, 4-228, 4-258, 4-264, 4-268, 4-285, 4-289, 4-290, 4-291, 4-293, 4-294, 4-295, 4-296, 

4-297, 4-298, 4-302, 4-305, 4-308, 4-310, 4-383, 4-398, 4-401, 6-18

Proposed Action, vii, viii, ix, xiv, xvi, xvii, 1-3, 1-4, 1-5, 1-6, 1-22, 1-25, 1-27, 1-28, 1-29, 2-1, 2-3, 2-4, 

2-20, 2-21, 2-23, 2-24, 2-27, 2-28, 2-34, 2-35, 3-1, 3-3, 3-4, 3-5, 3-8, 3-11, 3-16, 3-17, 3-18, 3-20, 

3-22, 3-23, 3-27, 3-29, 3-30, 3-31, 3-32, 3-35, 3-36, 3-37, 4-4, 4-5, 4-9, 4-11, 4-18, 4-24, 4-25, 

4-27, 4-42, 4-49, 4-52, 4-59, 4-61, 4-65, 4-71, 4-74, 4-75, 4-76, 4-78, 4-79, 4-80, 4-81, 4-82, 4-83, 

4-85, 4-86, 4-87, 4-98, 4-99, 4-105, 4-108, 4-110, 4-112, 4-120, 4-126, 4-130, 4-138, 4-142, 

4-143, 4-147, 4-151, 4-152, 4-153, 4-154, 4-155, 4-159, 4-160, 4-161, 4-167, 4-168, 4-171, 4-172, 

4-173, 4-175, 4-176, 4-177, 4-189, 4-193, 4-195, 4-197, 4-198, 4-199, 4-200, 4-201, 4-202, 4-203, 

4-207, 4-208, 4-209, 4-210, 4-211, 4-213, 4-215, 4-216, 4-218, 4-226, 4-229, 4-230, 4-231, 4-232, 

4-233, 4-235, 4-236, 4-237, 4-238, 4-239, 4-240, 4-241, 4-242, 4-243, 4-244, 4-248, 4-260, 4-261, 

4-262, 4-263, 4-264, 4-265, 4-266, 4-267, 4-268, 4-270, 4-272, 4-273, 4-275, 4-277, 4-278, 4-279, 

4-280, 4-281, 4-282, 4-297, 4-299, 4-300, 4-301, 4-302, 4-304, 4-305, 4-307, 4-309, 4-310, 4-311, 

4-312, 4-313, 4-314, 4-321, 4-322, 4-325, 4-327, 4-329, 4-331, 4-332, 4-333, 4-342, 4-343, 4-344, 

4-345, 4-346, 4-348, 4-351, 4-353, 4-354, 4-355, 4-357, 4-359, 4-367, 4-368, 4-370, 4-371, 4-373, 

4-374, 4-376, 4-377, 4-379, 4-381, 4-384, 4-385, 4-388, 4-389, 4-390, 4-391, 4-394, 4-395, 4-404, 

4-408, 4-409, 4-410, 4-413, 4-415, 4-418, 4-425, 4-427, 4-431, 4-437, 4-441, 4-442, 4-446, 4-451, 

4-452, 4-455, 4-459, 4-460, 5-3, 5-4, 5-5, 6-3, 6-7, 6-12, 6-14
Keyword Index Keywords-17

Protected Species Observer (PSO), xi, xii, xiii, xxiv, 1-12, 2-5, 2-6, 2-8, 2-9, 2-11, 2-12, 2-13, 2-14, 

2-15, 2-16, 2-18, 2-22, 2-26, 2-33, 2-35, 2-42, 2-43, 2-44, 2-45, 2-48, 2-49, 4-57, 4-58, 4-60, 4-68, 

4-72, 4-90, 4-91, 4-92, 4-96, 4-100, 4-101, 4-102, 4-103, 4-106, 4-107, 4-110, 4-119, 4-123, 

4-138, 4-140, 4-144, 4-145, 4-148, 4-162, 4-163, 4-168, 4-169, 4-170, 4-175, 4-179, 4-208, 4-236, 

4-237, 4-273, 4-292, 4-303, 4-304, 4-306, 4-328, 4-351, 4-375, 4-428, 4-442, 4-447, 4-451, 4-455

Ramp-Up, 1-11, 2-5, 2-39, 2-43, 2-45, 2-48, 3-23, 4-57, 4-60, 4-90, 4-91, 4-95, 4-96, 4-102, 4-139, 

4-140, 4-162, 4-163, 4-168, 4-187, 4-224, 4-292, 4-364, 4-365, 4-428

Recreational Fisheries, xiii, xv, xvi, xx, xxvi, 2-23, 2-24, 2-33, 2-37, 3-35, 3-42, 3-43, 4-7, 4-16, 4-75, 

4-82, 4-84, 4-86, 4-87, 4-88, 4-155, 4-156, 4-157, 4-160, 4-182, 4-198, 4-202, 4-203, 4-233, 

4-235, 4-255, 4-262, 4-265, 4-268, 4-341, 4-361, 4-362, 4-363, 4-364, 4-365, 4-366, 4-367, 4-368, 

4-369, 4-370, 4-371, 4-372, 4-373, 4-374, 4-375, 4-376, 4-377, 4-378, 4-379, 4-380, 4-381, 4-382, 

4-396, 4-409, 4-412

Recreational Resources, xv, 2-24, 2-25, 4-5, 4-292, 4-300, 4-425

Renewable Energy, vii, x, xvi, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-28, 1-29, 2-3, 2-5, 2-6, 2-7, 2-11, 2-20, 

2-21, 3-3, 3-7, 3-8, 3-9, 3-11, 3-13, 3-16, 3-17, 3-19, 3-20, 3-21, 3-22, 3-24, 3-25, 3-29, 3-30, 3-31, 

3-35, 3-39, 4-3, 4-4, 4-8, 4-13, 4-25, 4-78, 4-79, 4-80, 4-81, 4-82, 4-110, 4-121, 4-142, 4-143, 

4-152, 4-153, 4-155, 4-178, 4-198, 4-201, 4-217, 4-225, 4-227, 4-231, 4-232, 4-233, 4-235, 4-244, 

4-251, 4-262, 4-265, 4-291, 4-300, 4-301, 4-314, 4-322, 4-323, 4-344, 4-347, 4-351, 4-353, 4-354, 

4-357, 4-359, 4-368, 4-369, 4-370, 4-385, 4-387, 4-389, 4-390, 4-395, 4-396, 4-399, 4-402, 4-403, 

4-405, 4-406, 4-407, 4-410, 4-412, 4-414, 4-426, 4-434, 4-436, 4-439, 4-441, 4-444, 4-445, 4-448, 

4-450, 4-453, 4-454, 4-457, 4-460, 4-461, 5-4, 6-3, 6-5, 6-14, 6-15, 6-17

Routine Activities, 2-32, 3-16, 3-17, 4-25, 4-72, 4-73, 4-75, 4-76, 4-86, 4-88, 4-96, 4-97, 4-98, 4-100, 

4-103, 4-104, 4-105, 4-106, 4-107, 4-108, 4-109, 4-110, 4-111, 4-112, 4-113, 4-118, 4-119, 4-120, 

4-123, 4-130, 4-146, 4-148, 4-149, 4-159, 4-161, 4-165, 4-166, 4-168, 4-170, 4-171, 4-172, 4-174, 

4-175, 4-176, 4-183, 4-196, 4-197, 4-204, 4-206, 4-208, 4-209, 4-210, 4-212, 4-214, 4-215, 4-224, 

4-229, 4-230, 4-236, 4-238, 4-239, 4-241, 4-242, 4-243, 4-250, 4-260, 4-269, 4-271, 4-272, 4-273, 

4-274, 4-276, 4-278, 4-279, 4-280, 4-281, 4-291, 4-298, 4-302, 4-303, 4-305, 4-306, 4-308, 4-309, 

4-310, 4-311, 4-312, 4-318, 4-320, 4-322, 4-325, 4-326, 4-328, 4-330, 4-331, 4-332, 4-337, 4-343, 

4-348, 4-350, 4-351, 4-352, 4-354, 4-355, 4-356, 4-358, 4-360, 4-364, 4-367, 4-368, 4-371, 4-373, 

4-375, 4-377, 4-378, 4-380, 4-385, 4-387, 4-393, 4-402, 4-407, 4-411, 4-412, 4-413, 4-414, 4-415, 

4-416, 4-417, 4-429, 4-430, 4-441

Sargassum, xiii, xv, xvi, xix, xxv, 2-23, 2-24, 2-33, 2-37, 4-7, 4-126, 4-127, 4-136, 4-138, 4-139, 

4-140, 4-147, 4-150, 4-161, 4-163, 4-182, 4-196, 4-197, 4-246, 4-287, 4-290, 4-315, 4-316, 4-317, 

4-318, 4-319, 4-320, 4-321, 4-322, 4-323, 4-324, 4-325, 4-326, 4-327, 4-328, 4-329, 4-330, 4-331, 

4-332, 4-333, 4-334, 4-343

Sea Turtles, xiii, xv, xviii, xxi, xxiv, xxv, 1-9, 1-11, 2-4, 2-6, 2-7, 2-8, 2-11, 2-13, 2-15, 2-17, 2-19, 

2-20, 2-23, 2-24, 2-30, 2-33, 2-35, 2-37, 2-40, 2-43, 2-44, 2-48, 2-49, 3-33, 3-47, 4-7, 4-10, 4-16, 

4-17, 4-53, 4-71, 4-91, 4-92, 4-94, 4-102, 4-104, 4-106, 4-107, 4-111, 4-119, 4-126, 4-127, 4-128, 

4-129, 4-130, 4-131, 4-132, 4-133, 4-134, 4-135, 4-136, 4-137, 4-138, 4-139, 4-140, 4-141, 4-142, 
Keywords-18 Gulf of Mexico G&G Activities Programmatic EIS

4-143, 4-144, 4-145, 4-146, 4-147, 4-148, 4-149, 4-150, 4-151, 4-152, 4-153, 4-154, 4-155, 4-156, 

4-157, 4-158, 4-159, 4-160, 4-161, 4-162, 4-163, 4-164, 4-165, 4-166, 4-167, 4-168, 4-169, 4-170, 

4-171, 4-172, 4-173, 4-174, 4-175, 4-176, 4-177, 4-178, 4-179, 4-214, 4-285, 4-286, 4-288, 4-292, 

4-293, 4-294, 4-295, 4-297, 4-298, 4-299, 4-302, 4-303, 4-304, 4-306, 4-307, 4-308, 4-310, 4-312, 

4-316, 4-318, 4-320, 4-321, 4-334, 5-3 

Seafloor-Disturbing Activities, xi, xxiv, 2-4, 2-24, 2-36, 3-14, 3-29, 3-30, 4-194, 4-201, 4-220, 4-227, 

4-228, 4-230, 4-233, 4-236, 4-238, 4-241, 4-243, 4-244, 4-245, 4-296, 4-297, 4-298, 4-301, 4-347, 

4-349, 4-350, 4-352, 4-354, 4-358, 4-386, 4-387, 4-390, 4-393, 4-394, 4-395, 4-406, 4-410, 5-3 

Seagrass, xv, 2-25, 3-50, 4-7, 4-16, 4-140, 4-180, 4-285, 4-287, 4-289, 4-361

Sea-Level Rise, xvi, 3-36, 3-49, 3-50, 4-204, 4-434, 4-435

Seasonal Restrictions, xi, xvii, 1-11, 2-10, 2-11, 2-13, 2-14, 2-16, 2-18, 2-35, 2-40, 4-54, 4-88, 4-89, 

4-98, 4-99, 4-100, 4-120, 4-125, 4-161, 4-166, 4-168, 4-177, 4-204, 4-206, 4-208, 4-209, 4-236, 

4-238, 4-269, 4-273, 4-287, 4-302, 4-304, 4-305, 4-306, 4-308, 4-325, 4-326, 4-327, 4-328, 4-329, 

4-348, 4-350, 4-352, 4-371, 4-373, 4-375, 4-376, 4-411, 4-412, 4-413, 4-414, 4-438, 4-442, 4-443, 

4-447, 4-451, 4-456

Seismic Airgun Survey Protocol, xi, 2-5, 2-6, 2-8, 2-9, 2-10, 2-12, 2-14, 2-16, 2-18, 2-22, 4-57, 4-60, 

4-72, 4-90, 4-97, 4-103, 4-106, 4-107, 4-111, 4-118, 4-119, 4-123, 4-139, 4-162, 4-394

Settlement Agreement, xii, xxi, 1-10, 1-11, 1-12, 1-13, 1-14, 1-17, 1-25, 2-3, 2-6, 2-7, 2-8, 2-9, 2-10, 

2-11, 2-13, 2-15, 2-17, 2-19, 2-20, 2-38, 2-40, 2-41, 2-45, 4-88, 4-96, 4-160, 4-162, 4-204, 4-235, 

4-269, 4-302, 4-325, 4-348, 4-371, 4-411, 4-428, 4-429, 4-436, 4-437, 4-442, 4-447, 4-451, 4-453, 

4-455, 4-457

Shallow Test Well, 3-5, 3-20, 3-21, 3-26, 3-31, 3-32, 4-64, 4-66, 4-69, 4-70, 4-90, 4-122, 4-142, 

4-143, 4-144, 4-145, 4-146, 4-154, 4-162, 4-194, 4-195, 4-254, 4-258, 4-259, 4-264, 4-266, 4-269, 

4-271, 4-274, 4-296, 4-302, 4-405

Ship Strike, 2-23, 4-67, 4-68, 4-82, 4-155

Side-Scan Sonar, 2-6, 3-12, 3-13, 3-15, 3-17, 3-18, 3-19, 4-3, 4-4, 4-24, 4-26, 4-27, 4-42, 4-46, 4-58, 

4-60, 4-61, 4-62, 4-63, 4-125, 4-129, 4-130, 4-131, 4-132, 4-136, 4-137, 4-141, 4-179, 4-182, 

4-189, 4-199, 4-217, 4-222, 4-245, 4-249, 4-251, 4-252, 4-262, 4-283, 4-289, 4-292, 4-314, 4-336, 

4-339, 4-345, 4-360, 4-363, 4-364, 4-382, 4-439, 4-444, 4-448, 4-453, 4-457, 5-3 

Soft Bottom, xxiv, 2-36, 4-180, 4-186, 4-194, 4-200, 4-201, 4-218, 4-219, 4-221, 4-229, 4-245, 

4-296, 4-297, 4-361, 5-3 

Sound Exposure Level (SEL), 2-40, 2-42, 4-30, 4-31, 4-32, 4-33, 4-36, 4-45, 4-46, 4-47, 4-50, 4-51, 

4-55, 4-59, 4-61, 4-62, 4-63, 4-134, 4-185

Sound Pressure Level (SPL), 3-19, 4-31, 4-32, 4-33, 4-35, 4-62, 4-134, 4-186

Stand-Off Distance, xiv, xv, xvi, xx, xxv, 2-24, 2-37, 3-13, 3-17, 3-27, 3-36, 3-37, 3-39, 3-40, 3-41, 

3-42, 3-43, 3-45, 3-47, 3-48, 4-4, 4-15, 4-336, 4-340, 4-341, 4-342, 4-343, 4-344, 4-346, 4-347, 
Keyword Index Keywords-19

4-348, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 4-360, 4-361, 

4-363, 4-366, 4-367, 4-368, 4-370, 4-371, 4-372, 4-375, 4-377, 4-378, 4-379, 4-380, 4-381, 4-382, 

4-401, 4-402, 4-403, 4-404, 4-405, 4-407, 4-408, 4-409, 4-410, 4-411, 4-412, 4-413, 4-414, 4-415, 

4-417, 4-418, 4-419

Subbottom Profiler, 2-6, 3-12, 3-15, 3-17, 3-18, 3-19, 4-3, 4-4, 4-24, 4-26, 4-27, 4-42, 4-46, 4-58, 

4-60, 4-61, 4-62, 4-63, 4-125, 4-129, 4-130, 4-131, 4-132, 4-136, 4-137, 4-141, 4-142, 4-166, 

4-170, 4-179, 4-182, 4-189, 4-190, 4-191, 4-217, 4-222, 4-245, 4-249, 4-251, 4-252, 4-262, 4-283, 

4-289, 4-292, 4-314, 4-336, 4-339, 4-360, 4-363, 4-382, 4-439, 4-444, 4-448, 4-453, 4-457, 5-3 

Threatened and Endangered Species, vii, 1-5, 1-26, 2-19, 2-24, 2-32, 2-33, 4-8, 4-20, 4-21, 4-25, 

4-35, 4-46, 4-47, 4-48, 4-49, 4-50, 4-55, 4-57, 4-59, 4-61, 4-63, 4-96, 4-101, 4-112, 4-113, 4-120, 

4-126, 4-130, 4-180, 4-194, 4-218, 4-221, 4-222, 4-247, 4-250, 4-254, 4-285, 4-299, 4-317, 5-4, 

6-7, 6-16

Threshold Shift

Permanent, xxiv, 1-23, 2-35, 2-49, 4-12, 4-28, 4-30, 4-31, 4-32, 4-33, 4-36, 4-39, 4-49, 4-50, 4-55, 

4-57, 4-60, 4-63, 4-77, 4-86, 4-91, 4-96, 4-101, 4-110, 4-122, 4-133, 4-134, 4-139, 4-140, 

4-141, 4-142, 4-163, 4-168, 4-170, 4-292, 4-293, 5-3 

Temporary, 1-21, 1-23, 2-40, 2-49, 4-12, 4-28, 4-30, 4-31, 4-32, 4-33, 4-41, 4-56, 4-60, 4-77, 4-86, 

4-95, 4-102, 4-133, 4-134, 4-139, 4-140, 4-141, 4-142, 4-163, 4-168, 4-169, 4-185, 4-186, 

4-187, 4-189, 4-191, 4-192, 4-193, 4-225, 4-292, 4-293, 4-338, 4-339, 4-364, 5-3 

Tourism, xv, 2-25, 3-43, 4-5, 4-151, 4-363, 4-423, 4-429, 4-430, 4-434, 4-438, 4-440, 4-443, 4-445, 

4-448, 4-449, 4-454, 4-458, 4-462, 6-5, 6-9 

Trash and Debris, xiv, xv, xvi, xviii, xix, 2-4, 2-24, 2-33, 3-17, 3-27, 3-28, 3-29, 3-36, 3-37, 3-38, 

3-39, 3-40, 3-41, 3-42, 3-43, 3-44, 3-45, 3-47, 3-48, 4-4, 4-24, 4-70, 4-71, 4-73, 4-84, 4-86, 4-87, 

4-89, 4-92, 4-93, 4-95, 4-97, 4-101, 4-103, 4-104, 4-106, 4-107, 4-110, 4-111, 4-112, 4-119, 

4-123, 4-124, 4-125, 4-129, 4-146, 4-147, 4-149, 4-156, 4-159, 4-160, 4-161, 4-163, 4-164, 4-165, 

4-166, 4-168, 4-169, 4-170, 4-171, 4-172, 4-174, 4-175, 4-176, 4-178, 4-179, 4-182, 4-193, 4-194, 

4-196, 4-200, 4-202, 4-205, 4-206, 4-209, 4-210, 4-212, 4-214, 4-217, 4-222, 4-225, 4-226, 4-229, 

4-232, 4-235, 4-236, 4-237, 4-238, 4-239, 4-241, 4-243, 4-245, 4-249, 4-259, 4-260, 4-266, 4-268, 

4-270, 4-271, 4-272, 4-273, 4-274, 4-276, 4-278, 4-279, 4-280, 4-282, 4-283, 4-289, 4-295, 4-296, 

4-298, 4-301, 4-302, 4-303, 4-304, 4-305, 4-306, 4-307, 4-308, 4-309, 4-310, 4-312, 4-313, 4-314, 

4-316, 4-319, 4-320, 4-322, 4-324, 4-325, 4-326, 4-328, 4-330, 4-331, 4-332, 4-334

Vertical Seismic Profile (VSP), 1-8, 2-48, 3-5, 3-6, 3-20, 3-23, 4-3, 4-26, 4-121, 4-130, 4-139, 4-152, 

4-177, 4-189, 4-198, 4-216, 4-227, 4-231, 4-244, 4-251, 4-262, 4-283, 4-300, 4-322, 4-337, 4-343, 

4-351, 4-353, 4-354, 4-357, 4-359, 4-360, 4-364, 4-368, 4-381, 4-382, 4-386, 4-389, 4-395, 4-405, 

4-419, 4-428, 4-438, 4-442, 4-447, 4-451, 4-455

Vessel Strike, xi, 2-4, 2-7, 2-9, 2-12, 2-14, 2-15, 2-18, 2-22, 4-28, 4-66, 4-68, 4-72, 4-75, 4-90, 

4-123, 4-144, 4-145, 4-157, 4-162, 4-169, 4-256, 4-265, 4-318
Keywords-20 Gulf of Mexico G&G Activities Programmatic EIS

Vessel Traffic, xiv, xv, xvi, xviii, xix, xx, xxiv, xxv, 2-23, 2-24, 2-33, 2-36, 2-37, 3-17, 3-21, 3-22, 3-23, 

3-27, 3-36, 3-37, 3-38, 3-39, 3-40, 3-41, 3-42, 3-43, 3-44, 3-45, 3-47, 3-48, 4-4, 4-7, 4-14, 4-15, 

4-24, 4-66, 4-67, 4-68, 4-73, 4-75, 4-76, 4-78, 4-79, 4-81, 4-82, 4-83, 4-86, 4-87, 4-88, 4-89, 4-90, 

4-93, 4-95, 4-97, 4-103, 4-104, 4-106, 4-107, 4-110, 4-111, 4-112, 4-119, 4-122, 4-123, 4-124, 

4-125, 4-129, 4-144, 4-145, 4-149, 4-153, 4-155, 4-159, 4-160, 4-161, 4-162, 4-163, 4-164, 4-165, 

4-168, 4-169, 4-170, 4-172, 4-174, 4-175, 4-176, 4-178, 4-179, 4-189, 4-199, 4-203, 4-241, 4-249, 

4-253, 4-255, 4-256, 4-257, 4-260, 4-263, 4-264, 4-265, 4-266, 4-267, 4-268, 4-269, 4-270, 4-271,

4-273, 4-274, 4-276, 4-278, 4-279, 4-280, 4-282, 4-283, 4-310, 4-316, 4-318, 4-320, 4-322, 4-323, 

4-324, 4-325, 4-326, 4-328, 4-330, 4-331, 4-332, 4-334, 4-336, 4-340, 4-342, 4-343, 4-344, 4-345, 

4-346, 4-347, 4-348, 4-349, 4-350, 4-351, 4-352, 4-353, 4-354, 4-355, 4-356, 4-357, 4-358, 4-359, 

4-360, 4-361, 4-363, 4-366, 4-367, 4-368, 4-369, 4-370, 4-371, 4-372, 4-375, 4-377, 4-378, 4-379, 

4-380, 4-381, 4-382, 4-388, 4-389, 4-394, 4-400, 4-401, 4-402, 4-403, 4-404, 4-405, 4-407, 4-408, 

4-409, 4-410, 4-411, 4-412, 4-413, 4-414, 4-415, 4-416, 4-417, 4-419, 4-429, 4-430, 4-438, 4-443, 

4-448

Vibracoring, 1-29, 3-12, 3-13, 3-14, 3-16, 3-25, 3-30, 4-3, 4-226, 4-255, 4-296, 4-385, 4-402, 4-403, 

4-405

Waste Disposal, 4-427, 4-436, 4-441, 4-446, 4-450, 4-455, 4-459

Water Quality, xv, 2-24, 2-25, 3-48, 3-49, 4-5, 4-6, 4-84, 4-195, 4-228, 4-267, 4-289, 4-320, 4-322, 

4-323, 4-324, 4-325, 4-326, 4-327, 4-328, 4-329, 4-331, 4-332, 4-333, 4-334, 4-432

Western Planning Area (WPA), vii, viii, 1-3, 1-6, 1-18, 2-5, 2-6, 2-40, 3-6, 3-8, 3-22, 3-30, 3-36, 3-37, 

3-38, 3-40, 3-45, 3-46, 3-47, 4-47, 4-48, 4-49, 4-62, 4-78, 4-80, 4-82, 4-83, 4-86, 4-87, 4-90, 

4-138, 4-139, 4-141, 4-144, 4-152, 4-153, 4-154, 4-155, 4-159, 4-161, 4-180, 4-181, 4-200, 4-203, 

4-205, 4-207, 4-221, 4-265, 4-268, 4-291, 4-348, 4-350, 4-364, 4-371, 4-373, 4-374, 4-398, 4-400, 

6-3 

Wetlands, xv, 2-25, 3-40, 3-48, 3-50, 4-7, 4-202, 4-267, 4-420, 4-431, 4-435

Whale

Beaked, xxi, xxiii, 1-20, 2-19, 2-20, 2-33, 2-40, 4-18, 4-29, 4-34, 4-45, 4-52, 4-55, 4-65, 4-68, 4-90, 

4-94, 4-100, 4-113, 4-114, 4-116, 4-117

Dwarf Sperm, 4-45, 4-51, 4-68

Humpback, 2-48, 4-18, 4-38, 4-285

Pygmy Sperm, xxi, xxiii, 2-33, 2-49, 4-57, 4-60, 4-90, 4-91, 4-92, 4-100

Sperm, xvii, xxi, xxiii, 1-9, 1-20, 2-8, 2-19, 2-20, 2-33, 2-35, 2-39, 2-40, 4-19, 4-20, 4-38, 4-39, 

4-44, 4-46, 4-47, 4-48, 4-49, 4-50, 4-51, 4-55, 4-59, 4-61, 4-63, 4-65, 4-68, 4-90, 4-91, 4-92, 

4-94, 4-97, 4-100, 4-101, 4-113, 4-114, 4-116, 4-117, 4-125

Wide Azimuth (WAZ) Survey, 1-11, 3-6, 3-18, 3-22, 3-23, 3-27, 4-25, 4-26, 4-42, 4-46, 4-47, 4-48, 

4-49, 4-50, 4-64, 4-92, 4-130, 4-143, 4-148, 4-163, 4-227, 4-255, 4-270, 4-278, 4-337, 4-349, 

4-364, 4-372, 4-402, 4-428, 4-438, 4-442, 4-447, 4-451, 4-456
APPENDIX A 

AGREEMENTS AND COOPERATING AGENCY LETTERS

Gulf of Mexico G&G Activities Programmatic EIS A-3
A-4 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-5
A-6 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-7
A-8 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-9
A-10 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-11
A-12 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-13
A-14 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-15
A-16 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-17
A-18 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-19
A-20 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-21
A-22 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-23
A-24 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-25
A-26 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-27
A-28 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-29
A-30 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-31
A-32 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-33
A-34 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-35
A-36 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-37
A-38 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-39
A-40 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-41
A-42 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-43
A-44 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-45
A-46 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-47
A-48 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-49
A-50 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-51
A-52 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-53
A-54 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-55
A-56 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-57
A-58 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-59
A-60 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-61
A-62 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-63
A-64 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-65
A-66 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-67
A-68 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-69
A-70 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-71
A-72 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-73
A-74 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-75
A-76 Agreements and Cooperating Agency Letters
Gulf of Mexico G&G Activities Programmatic EIS A-77
A-78 Agreements and Cooperating Agency Letters
APPENDIX B 

PROTECTIVE MEASURES AND MITIGATION 

AND REGULATORY REQUIREMENTS

Gulf of Mexico G&G Activities Programmatic EIS B-iii

TABLE OF CONTENTS

Page

LIST OF FIGURES............................................................................................................................ B-vii

LIST OF TABLES.............................................................................................................................. B-vii

ABBREVIATIONS AND ACRONYMS ............................................................................................... B-ix

1 PROTECTIVE MEASURES AND MITIGATION.......................................................................... B-1

1.1 Current Regulations............................................................................................................. B-2

1.1.1 G&G Requirements Specified in the OCSLA and Its Regulations.......................... B-2

1.1.2 BOEM Stipulations, Mitigation, and Protective Measures ...................................... B-3

1.2 Protective Measures Included in the Alternatives ............................................................... B-5

1.2.1 Measures Applicable to All Surveys........................................................................ B-8

1.2.1.1. Guidance for Vessel Strike Avoidance .................................................... B-8 

1.2.1.2 Guidance for Marine Debris Awareness.................................................. B-9 

1.2.1.3 Avoidance of Sensitive Seafloor Resources ........................................... B-9 

1.2.1.4 Guidance for Military Coordination ........................................................ B-12

1.2.2 Additional Mitigation for Oil and Gas Program Surveys........................................ B-13

1.2.2.1 Additional Avoidance of Historic and Prehistoric Sites.......................... B-13

1.2.2.2 Additional Shallow Hazards Guidance .................................................. B-13

1.2.2.3 Guidance for Conducting Ancillary Activities......................................... B-13

1.2.3 Additional Mitigation for Renewable Energy Program Surveys ............................ B-14

1.2.4 Seismic Airgun Survey Protocol............................................................................ B-14

1.2.4.1 Ramp-Up................................................................................................ B-15

1.2.4.2 Exclusion Zone ...................................................................................... B-16

1.2.4.3 Exclusion Zone Monitoring by Protected Species Observers ............... B-16

1.2.4.4 Shutdown Requirements ....................................................................... B-17

1.2.4.5 Passive Acoustic Monitoring.................................................................. B-17

1.2.4.6 Summary of Visual Observer Requirements......................................... B-19

1.3 Additional Protective Measures Included in the Alternatives ............................................ B-21

1.3.1 Non-Airgun HRG Survey Protocol......................................................................... B-21

1.3.1.1. Exclusion Zone ...................................................................................... B-22

1.3.1.2 Exclusion Zone Monitoring by Protected Species Observers ............... B-22

1.3.1.3 Shutdown Requirements ....................................................................... B-23

1.3.2 Expanded PSO Program....................................................................................... B-23

1.3.3 Geographic Separation Between Simultaneous Seismic Airgun Surveys............ B-24

1.3.4 Reduced Level of Activity...................................................................................... B-25
B-iv Protective Measures and Mitigation and Regulatory Requirements

1.3.5 Use of PAM Required............................................................................................ B-25

1.3.6 Coastal Water Seasonal Restrictions.................................................................... B-26

1.3.7 Area Closures........................................................................................................ B-27

1.3.8 Areas with Additional Restrictions......................................................................... B-28

2 FEDERAL REGULATIONS AND AGENCIES........................................................................... B-29

2.1 Federal Regulations........................................................................................................... B-29

2.1.1 National Environmental Policy Act ........................................................................ B-29

2.1.2 Outer Continental Shelf Lands Act........................................................................ B-30

2.1.3 Endangered Species Act....................................................................................... B-33

2.1.4 Marine Mammal Protection Act ............................................................................. B-34

2.1.5 Coastal Zone Management Act............................................................................. B-35

2.1.6 Magnuson-Stevens Fishery Conservation and Management Act ........................ B-36

2.1.7 Clean Air Act.......................................................................................................... B-37

2.1.8 Clean Water Act .................................................................................................... B-37

2.1.9 Rivers and Harbors Act ......................................................................................... B-39

2.1.10 National Historic Preservation Act......................................................................... B-39

2.1.11 Marine Protection, Research, and Sanctuaries Act.............................................. B-40

2.1.12 National Marine Sanctuaries Act........................................................................... B-40

2.1.13 Migratory Bird Treaty Act....................................................................................... B-42

2.1.14 Fish and Wildlife Coordination Act ........................................................................ B-43

2.1.15 CFR Title 30: Mineral Resources ......................................................................... B-43

2.1.15.1 Notice to Lessees and Operators.......................................................... B-44

2.1.16 Executive Order 12114 – Environmental Effects Abroad of Major Federal 

Actions ............................................................................................................... B-45

2.1.17 Executive Order 12898 – Federal Actions to Address Environmental Justice 

in Minority Populations and Low-Income Populations .......................................... B-45

2.1.18 Executive Order 12989 – Economy and Efficiency in Government Procurement 

through Compliance with Certain Immigration and Naturalization Act 

Provisions .............................................................................................................. B-45

2.1.19 Executive Order 13089 – Coral Reef Protection Act ............................................ B-46

2.1.20 Executive Order 13158 – Marine Protected Areas ............................................... B-46

2.1.21 Executive Order 13175 – Consultation and Coordination with Federally 

Recognized Indian Tribes...................................................................................... B-47

2.1.22 Executive Order 13547 – Stewardship of the Ocean, Our Coasts, and the 

Great Lakes ........................................................................................................... B-47
Gulf of Mexico G&G Activities Programmatic EIS B-v 

2.1.23 U.S./Mexico Transboundary Hydrocarbons Agreement and H.R. 1613 – 

Outer Continental Shelf Transboundary Hydrocarbon Agreements 

Authorization Act ................................................................................................... B-47

2.2 Federal Agencies ............................................................................................................... B-48

2.2.1 Bureau of Ocean Energy Management................................................................. B-48

2.2.2 Bureau of Safety and Environmental Enforcement............................................... B-48

2.2.3 National Oceanic and Atmospheric Administration............................................... B-49

3 STATE REGULATIONS AND AGENCIES................................................................................ B-50

3.1 Coastal Zone Management Act ......................................................................................... B-50

3.1.1 State of Florida Coastal Management Program.................................................... B-51

3.1.2 State of Alabama Coastal Management Program ................................................ B-52

3.1.3 State of Mississippi Coastal Management Program ............................................. B-54

3.1.4 State of Louisiana Coastal Management Program ............................................... B-55

3.1.5 State of Texas Coastal Management Program..................................................... B-57

4 REFERENCES CITED .............................................................................................................. B-59

ATTACHMENT 1: SEISMIC AIRGUN SURVEY PROTOCOL....................................................... B-63

ATTACHMENT 2: NON-AIRGUN HRG SURVEY PROTOCOL .................................................... B-73

Gulf of Mexico G&G Activities Programmatic EIS B-vii

LIST OF FIGURES

Page

Figure B-1. Area of Interest for the Proposed Action. .................................................................... B-1

Figure B-2. Alternative B Seasonal Restrictions for Coastal Waters and Other Closure 

Areas (as defined in the Amended Settlement Agreement as the Areas of 

Concern)..................................................................................................................... B-25

Figure B-3. Coastal Seasonal Restriction Area (Federal and State waters) Between 

February 1 and May 31 and Areas Requiring Passive Acoustic Monitoring 

for All Seismic Airgun Surveys for Alternatives C Through F.................................... B-27

Figure B-4. Alternative F Closure Areas (i.e., the Central Planning Area Closure Area, 

Eastern Planning Area Closure Area, Dry Tortugas Closure Area, and Flower 

Gardens Closure Area) and Seasonal Restrictions for Coastal Waters Between 

February 1 and May 31 and Areas Requiring Passive Acoustic Monitoring 

for All Seismic Airgun Surveys................................................................................... B-28

LIST OF TABLES

Page

Table B-1. Federal Regulations Applicable to Pre- and Post-lease Activities by Mineral 

Resource of Interest..................................................................................................... B-2

Table B-2. Applicability of Mitigation Measures to G&G Surveys by Alternative 

(indicates which mitigation measure is applicable to an alternative)........................... B-7

Table B-3. Observer Requirements for G&G Survey Types. ...................................................... B-20

Gulf of Mexico G&G Activities Programmatic EIS B-ix

ABBREVIATIONS AND ACRONYMS

3D three-dimensional

4D four-dimensional

ACAA Alabama Coastal Area Act

ACAMP Alabama Coastal Area Management Program

ACHP Advisory Council on Historic Preservation

ADCNR Alabama Department of Conservation and Natural Resources

ADEM Alabama Department of Environmental Management

AOI area of interest

BOEM Bureau of Ocean Energy Management

BSEE Bureau of Safety and Environmental Enforcement

CAA Clean Air Act

CATEX categorical exclusion

CD-ROM compact disc-read only memory

CEQ Council on Environmental Quality

CFDL Coastal Facilities Designation Line

CFR Code of Federal Regulation

CHIRP compressed high-intensity radiated pulse

CMP Coastal Management Program

CNRA coastal natural resource area

COA condition of approval

COP Construction and Operations Plan

CPA Central Planning Area

CWA Clean Water Act

CZM Coastal Zone Management

CZMA Coastal Zone Management Act

dB re 1 μPa decibels referenced to 1 micropascal

DEP Department of Environmental Protection

DOCD Development Operations Coordination Document

DPP Development and Production Plan

EA Environmental Assessment

EFH essential fish habitat

EIS Environmental Impact Statement

EPA Eastern Planning Area

EPAct Energy Policy Act

ESA Endangered Species Act

FCMP Florida Coastal Management Program
B-x Protective Measures and Mitigation and Regulatory Requirements

FMP Fishery Management Plan

FR Federal Register

FWCA Fish and Wildlife Coordination Act

FWS Fish and Wildlife Service (USDOI)

G&G geological and geophysical

GAP General Activities Plan

GOM Gulf of Mexico

H.R. House Resolution

HRG high-resolution geophysical

Hz hertz

IHA Incidental Harassment Authorization

ITA Incidental Take Authorization

ITS Incidental Take Statement

kHz kilohertz

km kilometer

LOA Letter of Authorization

LOCM Louisiana Office of Coastal Management

m meter

MARPOL International Convention for the Prevention of Pollution from Ships

MBTA Migratory Bird Treaty Act

MCP Mississippi Coastal Program

mi mile

MMPA Marine Mammal Protection Act

MMS Minerals Management Service

MODU mobile offshore drilling unit

MOU Memorandum of Understanding

MPA Marine Protected Area

MPPRCA Marine Plastic Pollution Research and Control Act

MPRSA Marine Protection, Research, and Sanctuaries Act

MSD marine sanitation device

MSFCMA Magnuson-Stevens Fishery Conservation and Management Act

NEPA National Environmental Policy Act

NHPA National Historic Preservation Act

NMFS National Marine Fisheries Service

nmi nautical mile

NMS National Marine Sanctuary

NMSA National Marine Sanctuary Act

NOAA National Oceanic and Atmospheric Administration
Gulf of Mexico G&G Activities Programmatic EIS B-xi

NOS National Ocean Service

NPDES National Pollutant Discharge Elimination System

NTL Notice to Lessees and Operators 

NWP Nationwide Permit

OBC ocean bottom cable

OBN ocean bottom node

OCS Outer Continental Shelf

OCSLA Outer Continental Shelf Lands Act

OMB Office of Management and Budget

ONMS Office of National Marine Sanctuary

P.L. Public Law

PAM passive acoustic monitoring

PSO protected species observer

rms root mean square

SAP Site Assessment Plan

TCMP Texas Coastal Management Program

U.S.C. United States Code

USACE U.S. Army Corps of Engineers

USCG U.S. Coast Guard

USDOC U.S. Department of Commerce

USDOD U.S. Department of Defense

USDOI U.S. Department of the Interior

USEPA U.S. Environmental Protection Agency

yd yard

Gulf of Mexico G&G Activities Programmatic EIS B-1 

1 PROTECTIVE MEASURES AND MITIGATION

The Bureau of Ocean Energy Management (BOEM) is proposing to authorize geological and 

geophysical (G&G) activities in connection with its Oil and Gas, Renewable Energy, and Marine 

Minerals Programs in Federal waters of the Gulf of Mexico (GOM) and adjacent State waters. The 

area of interest (AOI) for the proposed action includes the Federal OCS waters of the GOM within 

BOEM’s Gulf of Mexico WPA, CPA, and EPA. The AOI also includes the coastal (i.e., State) waters 

of Texas, Louisiana, Mississippi, Alabama, and Florida, extending from the coastline outside of 

estuaries seaward 3 nautical miles (nmi) (3.5 miles [mi]; 5.6 kilometers [km]) from Louisiana, 

Mississippi, and Alabama, and seaward to 9 nmi (10.4 mi; 16.7 km) from the coastlines of Texas and 

Florida (Figure B-1). BOEM does not approve G&G activities in State waters; however, since G&G 

activities in OCS waters can potentially impact resources in State waters (e.g., sound traveling from 

OCS areas into State waters), for purposes of impacts analysis in this Programmatic EIS, State 

waters were included in the AOI. 

Figure B-1. Area of Interest for the Proposed Action.

All G&G activities authorized by BOEM must comply with existing applicable law as 

described in Chapter 1.3 of this Programmatic EIS, including measures to avoid or reduce potential 

impacts from G&G activities. Compliance with existing applicable law and regulations – by BOEM 

as well as individual operators, when required – may result in additional measures or changes to the 

measures described here. In addition, a suite of protective measures is included in the proposed 
B-2 Protective Measures and Mitigation and Regulatory Requirements

action, as described in Chapter 2 of this Programmatic EIS. This appendix describes and discusses 

the rationale for the measures selected for the proposed action. 

1.1 CURRENT REQUIREMENTS

This section identifies current requirements for G&G activities, including G&G operator 

compliance with lease stipulations and other protective measures,such as applicable guidance 

documents. These requirements are included in the proposed action.

1.1.1 G&G Requirements Specified in the OCSLA and Its Regulations

The Outer Continental Shelf Lands Act (OCSLA) and implementing regulations at

30 CFR § 551.4 require a permit to conduct pre-lease G&G exploration for oil, gas, and sulphur 

resources. Authorizations for the exploration for other minerals in support of competitive leasing are 

granted pursuant to requirements outlined in 30 CFR § 580.3. Requirements for renewable energy 

are outlined in 30 CFR part 585. Permit applications must be submitted to BOEM in accordance 

with requirements outlined in 30 CFR § 551.5 and 30 CFR § 551.6, and further guidance provided in 

Letters to Permittees. The Letter to Permittees, dated January 20, 1989, specifies forms, maps, 

stipulations, and special provisions applicable to most permit activity. Requirements at 30 CFR part 

551 do not apply to G&G activities conducted by, or on behalf of, a lessee in a leased OCS block. 

Such G&G activities are governed by 30 CFR § 550.201 and by applicable Notices to Lessees and 

Operators (NTLs). Table B-1 identifies the appropriate Federal regulations and their applicability to 

select mineral resources and activity phase.

Table B-1. Federal Regulations Applicable to Pre- and Post-lease Activities by Mineral Resource of 

Interest. 

Regulatory Citation Mineral Resource Activity Phase

30 CFR part 550 Oil, gas, and sulphur Post-lease (i.e., on lease)

30 CFR part 551 Oil, gas, and sulphur Pre-lease or off-lease exploration or 

scientific research

30 CFR part 580a All minerals exclusive of oil, gas, 

and sulphur Pre-lease (prospecting)

30 CFR part 585 Renewable energy Post-lease

CFR = Code of Federal Regulations. a 30 CFR part 580 applies only to G&G activities in support of competitive leasing. For noncompetitive 

leasing for public works, authorizations are issued pursuant to Section 11 of the Outer Continental 

Shelf Lands Act.

The following summarizes key requirements of the OCSLA and its regulations:

• The G&G explorations for mineral resources may not be conducted on the OCS 

without a permit unless such activities are being conducted pursuant to a lease 

issued or maintained under the OCSLA.
Gulf of Mexico G&G Activities Programmatic EIS B-3 

• The G&G data must be obtained in a technologically safe and environmentally 

sound manner. Regulations at 30 CFR § 551.6 state that permit holders for G&G 

activities must not: 

− interfere with or endanger operations under any lease, right-of-way, 

easement, right-of-use, notice, or permit issued or maintained under the 

OCSLA; 

− cause harm or damage to life (including fishes and other aquatic life), 

property, or the marine, coastal, or human environment; 

− cause harm or damage to any mineral resource (in areas leased or not 

leased); 

− cause pollution; 

− disturb archaeological resources; 

− create hazardous or unsafe conditions; or 

− unreasonably interfere with or cause harm to other uses of the area.

• The G&G operators conducting activities under 30 CFR part 551 must 

immediately report to the Director of BOEM when: 

− hydrocarbon occurrences are detected; 

− environmental hazards are encountered that constitute an imminent threat to 

human life or property; or

− activities occur that adversely affect the environment, aquatic life, 

archaeological resources, or other uses of the area in which the exploration 

or scientific research activities are conducted.

1.1.2 BOEM Stipulations, Mitigation, and Protective Measures

BOEM currently requires operators to comply with a series of stipulations and protective 

measures during G&G activities in addition to requirements specified directly on the OCSLA and its 

regulations. These requirements generally represent mitigation measures designed to reduce or 

avoid impacts to sensitive resources. Such measures are implemented through regulations 

governing pre- and post-lease G&G activities. Key points consist of the following:

• Explosives Prohibition: Explosives cannot be used for G&G activities except 

under written authorization from BOEM’s Regional Supervisor. Further protective 

measures, including those required for compliance with the Endangered Species 

Act (ESA) and the Marine Mammal Protection Act (MMPA), also apply in the 

event that explosives are proposed for use.
B-4 Protective Measures and Mitigation and Regulatory Requirements

• Archaeological Resources: The permittee must report discovery of any 

archaeological resource (e.g., shipwreck or prehistoric site) to BOEM and take 

precautions to protect the resource from operational activities.

• Seismic Safety: All pipes, buoys, and other markers used in connection with 

seismic work must be properly flagged and lighted according to the navigation 

rules of the U.S. Army Corps of Engineers (USACE) and the U.S. Coast Guard 

(USCG).

BOEM provides additional guidance to lessees and operators through NTLs, conditions of 

approval (COAs), and best management practices. As defined by the Council on Environmental 

Quality (CEQ), mitigation includes the following:

(1) avoiding an impact by not taking a certain action or parts of an action; 

(2) minimizing an impact by limiting the degree or magnitude of the action and its 

implementation; 

(3) rectifying an impact by repairing, rehabilitating, or restoring the affected 

environment; 

(4) reducing or eliminating an impact over time, through preservation and 

maintenance operations during the life of the action; and

(5) compensating for an impact by replacing or providing substitute resources or 

environments.

Of these, BOEM’s regulated programs effectively use avoidance and minimization as the 

main, and most effective, strategy for environmental protection. BOEM assigns mitigation by 

imposing COAs on a plan, authorization, or permit. Mitigation is the effect of conditioned approval, 

which may originate from programmatic National Environmental Policy Act (NEPA) evaluations such 

as this one; from BOEM’s interpretations of regulations in NTLs; from the site-specific review of a 

plan, authorization, or permit in which additional impacts to resources need to be mitigated to the 

maximum extent practicable; or they may evolve into best management practices through common 

or accepted use.

The COAs enforce more than just environmental mitigations originating through the NEPA 

process and are used in many different contexts within the Oil and Gas, Renewable Energy, and 

Marine Minerals Programs considered in this Programmatic EIS. The COAs are used to pass on 

other requirements or advisories to operators, including the following:

(1) other approvals prerequisite to BOEM approval (e.g., Coastal Zone 

Management Act [CZMA]);

(2) safety precautions (e.g., hydrogen sulfide [H2S] present);
Gulf of Mexico G&G Activities Programmatic EIS B-5 

(3) post-approval submittals (e.g., surveys and interpretive reports);

(4) inspection requirements (e.g., pipeline pressure testing);

(5) pre-deployment notifications (e.g., U.S. Department of Defense [USDOD] 

space-use or warning areas); and

(6) reduction or avoidance of environmental impacts on biological, physical, or 

socioeconomic resources identified through NEPA analysis, including mitigation 

measures developed for this purpose. 

There are no programmatic mitigation measures that apply to G&G activities conducted in 

support of renewable energy development in the GOM; however, best management practices are 

documented in this Programmatic EIS for the Renewable Energy Program (USDOI, Minerals 

Management Service, 2007). In addition, standard operating conditions have been developed for 

G&G activities conducted in support of renewable energy development on the Atlantic OCS. Prior to 

the issuance of a renewable energy lease, BOEM prepares an environmental assessment (EA) and 

conducts consultations (i.e., ESA) as required by NEPA. This environmental review considers 

reasonably foreseeable consequences associated with G&G surveys. Conditions to minimize or 

eliminate impacts on protected species are included as stipulations of renewable energy leases and 

include vessel strike avoidance and marine debris awareness measures; protected species 

observers (PSOs); monitoring and exclusion zones; sound source verification; ramp-up, soft-start, 

and shutdown procedures; visibility-dependent, seasonal, and frequency-dependent restrictions for 

various activities; and multiple reporting requirements.

Similarly, at a programmatic level, there are no mitigation measures that apply to G&G 

activities under the Marine Minerals Program. Section 11 of the OCSLA requires BOEM’s 

authorization for non-energy marine minerals G&G prospecting on the OCS unless a Federal agency 

is performing the survey. Before authorizing any proposed prospecting, BOEM must undertake the 

necessary environmental review, including preparation of a NEPA document and consultations for 

protected species. Through the NEPA process, BOEM may identify mitigation measures to avoid or 

minimize environmental impacts during G&G surveys. Mitigation measures may be implemented as 

a condition of survey authorization.

1.2 PROTECTIVE MEASURES INCLUDED IN THE ALTERNATIVES

The proposed action includes protective measures that are applicable to all G&G surveys or 

specific survey types. The measures are listed here and their applicability to G&G survey types is 

summarized in Table B-2. Each measure is discussed in a separate subsection.
B-6 Protective Measures and Mitigation and Regulatory Requirements

Measures applicable to all G&G surveys for all alternatives (i.e., Alternatives A through G)

are as follows: 

• guidance for vessel strike avoidance;

• guidance for marine debris awareness;

• avoidance of sensitive benthic resources;

• guidance for shallow hazards survey and reporting;

• regulations for activities in or near National Marine Sanctuaries (NMSs); 

• guidance for avoidance of historic and prehistoric sites; and

• guidance for military coordination.

Additional measures applicable to G&G surveys for the Oil and Gas Program are as follows: 

• additional guidance for avoidance of historic and prehistoric sites;

• additional guidance for avoidance of shallow hazards; and

• guidance for ancillary activities.

Additional possible measures applicable to specific survey types, based on the selected 

alternative, include the following: 

• Seismic Airgun Survey Protocol, including the use of PSOs and passive acoustic 

monitoring (PAM); 

• Non-Airgun High-Resolution Geophysical (HRG) Survey Protocol, including use 

of PSOs;

• Expanded PSO Program;

• geographic separation between simultaneous seismic airgun surveys;

• reduced level of activity;

• use of PAM required;

• coastal water seasonal restrictions; and

• area closures.
Gulf of Mexico G&G Activities Programmatic EIS B-7 

Table B-2. Applicability of Mitigation Measures to G&G Surveys by Alternative (indicates which 

mitigation measure is applicable to an alternative). 

Survey Type

Mitigation Measures Survey 

Protocol

Seasonal 

Restrictions 

and Closures

Vessel Strike AvoidanceMarine Debris GuidanceAvoidance of Sensitive Benthic Communities Avoidance of Historic & Prehistoric Sites Shallow Hazards GuidanceNational 

Marine 

Sanctuary Regulations 

Military CoordinationAncillary Activity GuidanceImplement PSO ProgramImplement Expanded PSO ProgramMinimum Separation DistanceReduced Level of ActivityUse of PAM Strongly EncouragedUse of PAM RequiredSeismic Airgun Survey ProtocolNon-Airgun HRG Survey ProtocolCoastal Waters Seasonal RestrictionAreas of Concern within the EPA8CP

A, EP

A, Dry Tortugas, and Flower 

Garden Banks Closure Areas

Seismic Airgun

Surveys A-G A-G A-G A-G1 A-G1 A-G A-G A-G A,G B-F2

D3 B E A,G B-F4C-F5 A-G -- B6

, C

F7 B F 

HRG Non-airgun

Surveys with

Frequencies

>200 kHz

A-G A-G A-G A-G1 A-G1 A-G A-G -- -- -- -- -- -- -- -- -- -- -- --

HRG Non-airgun

Surveys with

Frequencies

≤200 kHz

A-G A-G A-G A-G1 A-G1 A-G A-G -- C-F -- -- -- -- -- -- C-F -- -- F 

Other G&G

Surveys A-G A-G A-G A-G1 A-G1 A-G A-G -- -- -- -- -- -- -- -- -- -- -- --

CP = Central Planning Area; EPA = Eastern Planning Area; ft = feet; G&G = geological and geophysical; 

HRG = high-resolution geophysical; kHz = kilohertz; m = meter; PAM = passive acoustic monitoring; 

PSO = protected species observer; -- = not applicable. 1 Avoidance of historic and prehistoric sites and sensitive benthic communities applies only to surveys that involve 

seafloor-disturbing activities. Seismic airgun surveys and non-airgun HRG surveys that do not disturb the 

seafloor are not required to avoid these sites or features. Non-airgun HRG surveys and most seismic airgun 

surveys (except those in which cables or sensors are placed in or on the seafloor) do not disturb the seafloor. 2 Expanded to include manatees and all water depths. 3 Expanded from Footnote 2 to include shutdown for all marine mammals except bow-riding or actively 

approaching dolphins (i.e., bottlenose, Fraser’s, Clymene’s, rough-toothed, striped, spinner, Atlantic spotted, 

pantropical, and Risso’s) and all water depths.. 4 During periods of reduced visibility for surveys in waters >100 m (328 ft). 5 PAM required for all airgun surveys at all times in the Mississippi Canyon and DeSoto Canyon OCS lease blocks. 6 Applies from (1) March 1 to April 30 in Federal coastal waters shoreward of the 20-m (66-ft) isobath (and a 5-km

[3-mi] buffer extending seaward from the 20-m [66-ft] isobath) and; (2) from January 1 to April 30 within the 

portion of these coastal waters falling within the boundaries of the Unusual Mortality Event in the northern GOM. 7 Applies to all coastal waters shoreward of the 20-m (66-ft) isobath between February 1 and May 31. 8 Does not apply to currently leased OCS blocks, any portion of the area encompassed by EPA Lease Sale 226, or 

neighboring OCS lease blocks adjacent to permitted survey areas but within an otherwise off limit area.
B-8 Protective Measures and Mitigation and Regulatory Requirements

1.2.1 Measures Applicable to All Surveys

The mitigation measures detailed here generally are applicable to all G&G surveys and 

ancillary activities. They are incorporated in lease stipulations, NTLs, or other guidance and 

implemented through COAs or stipulations during site-specific permit, authorization, and plan 

reviews.

1.2.1.1 Guidance for Vessel Strike Avoidance

All authorizations for shipboard surveys would include guidance for vessel strike avoidance 

per NTL 2016-BOEM-G01 (“Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting”). Key elements of the guidance are as follows:

(1) Vessel operators and crews must maintain a vigilant watch for all marine 

mammals and sea turtles, and slow down or stop the vessel, regardless of 

vessel size, to avoid striking protected species.

(2) When whales are sighted, vessels must maintain a distance of 91 meters (m) 

(100 yards [yd]) or more from the whale. If the whale is believed to be a North 

Atlantic right whale, vessels should maintain a minimum distance of 457 m 

(500 yd) from the animal (50 CFR § 2224.103).

(3) When sea turtles or small cetaceans are sighted, vessels must attempt to 

maintain a distance of 46 m (50 yd) or more whenever possible.

(4) When cetaceans are sighted while a vessel is underway, vessels must attempt 

to remain parallel to the animal’s course. Vessels must avoid excessive speed 

or abrupt changes in direction until the cetacean has left the area.

(5) Vessels must reduce speed to 10 knots (12 miles per hour) or less when mother

and calf pairs, pods, or large assemblages of cetaceans are observed near an 

underway vessel, when safety permits. A single cetacean at the surface may 

indicate the presence of submerged animals in the vicinity of the vessel; 

therefore, precautionary measures should always be exercised.

(6) Whales may surface in unpredictable locations or approach slow-moving 

vessels. When an animal is sighted in the vessel’s path or in close proximity to 

a moving vessel, reduce speed and shift the engine to neutral. Vessels must 

not engage the engines until the animals are clear of the area.

(7) Vessel crews would be required to report sightings of any injured or dead 

marine mammals or sea turtles to BOEM and the National Marine Fisheries 

Service (NMFS) within 24 hours, regardless of whether the injury or death was 

caused by their vessel.
Gulf of Mexico G&G Activities Programmatic EIS B-9 

1.2.1.2 Guidance for Marine Debris Awareness

All authorizations for shipboard surveys include guidance for marine debris awareness under 

the Bureau of Safety and Environmental Enforcement’s (BSEE’s) NTL 2015-G03 (“Marine Trash and 

Debris Awareness and Elimination”). All vessel operators, employees, and contractors actively 

engaged in G&G surveys must be briefed on marine trash and debris awareness and elimination as 

described in the NTL. Operators and lessees are required to post placards on all fixed and floating 

production facilities, and offshore employees must complete marine trash and debris training 

annually. The NTL 2015-BSEE-G03 provides information that applicants may use for this 

awareness training.

In addition, 30 CFR §§ 250.300(a) and (b)(6) prohibit the deliberate discharge of containers 

and other similar materials (i.e., trash and debris) into the marine environment, and 

30 CFR §§ 250.300(c) and (d) require durable identification markings on equipment, tools, 

containers (especially drums), and other materials, as well as the recording and reporting of items 

lost overboard to the District Manager through facility daily operations reports. Furthermore, the 

intentional jettisoning of trash has been the subject of strict laws such as the International 

Convention for the Prevention of Pollution from Ships (MARPOL) Annex V and the Marine Plastic 

Pollution Research and Control Act (MPPRCA), as well as regulations imposed by various agencies 

such as the USCG and U.S. Environmental Protection Agency (USEPA).

1.2.1.3 Avoidance of Sensitive Seafloor Resources

Avoidance is BOEM’s (and the CEQ’s) priority for mitigation. To avoid seafloor resources, 

BOEM must know enough about the nature of the seafloor area where activities are proposed so 

that activities can be moved to another area if sensitive resources are present. This applies to 

sensitive cultural resources such as shipwrecks and prehistoric archaeological resources, as well as 

sensitive benthic communities.

In addition to the cultural resources and benthic communities discussed in the following 

sections, there are many undersea cables and other infrastructure on the seafloor within the GOM 

planning areas. Applicants who propose seafloor-disturbing activities will be required to provide 

site-specific data identifying the existing cables and infrastructure for avoidance. Cable data are 

available from numerous sources, and applicants will have access to these data. Where 

appropriate, operators will be required to coordinate with the North American Submarine Cable 

Association to avoid impacts to submarine cable infrastructure.

Avoidance of historic and prehistoric sites, as well as sensitive benthic communities, applies 

only to surveys that involve seafloor-disturbing activities. Seismic airgun surveys and non-airgun 

HRG surveys that do not disturb the seafloor are not required to avoid these sites or features. 

Non-airgun HRG surveys and most seismic airgun surveys (except those in which cables or sensors 

are placed in or on the seafloor) do not disturb the seafloor.
B-10 Protective Measures and Mitigation and Regulatory Requirements

Avoidance of Sensitive Benthic Communities

BOEM requires site-specific information regarding sensitive benthic communities prior to 

approving any G&G activities involving seafloor-disturbing activities or placement of bottom-founded 

equipment or structures in the AOI. Required information includes mapping and avoidance plans as 

well as pre-deployment photographic surveys of areas where bottom-founded instrumentation and 

appurtenances are to be deployed. Seafloor-disturbing activities include drilling, anchoring, placing 

seafloor templates, discharging muds and cuttings, and installing pipelines. BOEM’s Renewable 

Energy Program has developed biological survey protocols that provide guidance for these 

site-specific surveys.

BOEM’s requirements for oil and gas activities in the GOM are set forth in two separate 

NTLs: one for seafloor communities in water depths <300 m (984 feet [ft]) (NTL 2009-G39, 

“Biologically-Sensitive Underwater Features and Areas”), and one for seafloor communities in water 

depths >300 m (984 ft) (NTL 2009-G40, “Deepwater Benthic Communities”). The NTLs should be 

referred to for specific requirements, including procedures for demonstrating compliance and 

supporting approval of operation. The resources to be protected and the policies to be applied for 

protection are summarized here. 

The shallower water NTL 2009-G39 addresses four features that are drawn from the 

Essential Fish Habitat (EFH) programmatic consultation with NMFS and that are defined and 

afforded protective policies as follows:

(1) Topographic features are isolated areas of moderate to high relief that provide

habitat for hard bottom communities of high biomass and diversity and for large

numbers of plant and animal species that provide support, either as shelter or 

food, for large numbers of commercially and recreationally important fishes. 

These features include the Flower Garden Banks and other coral banks. No 

bottom-disturbing activities may occur within 152 m (500 ft) of the designated 

“No Activity Zone” of a topographic feature (for maps of the zones, refer to

http://www.boem.gov/Topographic-Features-Stipulation-Map-Package/). Also, if 

more than two wells not from development operations are to be drilled from the 

same surface location within 3 mi (5 km) of a topographic feature, all drill 

cuttings and fluids must be shunted to the seabottom through a downpipe 

terminating no more than 10 m (33 ft) from the bottom. Any exception to these 

requirements can only be considered through an individual EFH consultation 

between BOEM and NMFS.

(2) Live bottoms (pinnacle trend features) are small, isolated, low- to moderaterelief carbonate reefal features or outcrops of unknown origin, or hard

substrates exposed by erosion that provide surface area for the growth of

sessile invertebrates and attract large numbers of fish. No bottom-disturbing 

activities may occur within 30 m (98 ft) of any pinnacle trend feature with a 

vertical relief of 2 m (8 ft) or more. Any exception to these requirements can 
Gulf of Mexico G&G Activities Programmatic EIS B-11

only be considered through an individual EHF consultation between BOEM and 

NMFS. An individual EHF consultation is also required if a proposed pipeline 

would transport liquid hydrocarbons with an API gravity of 45° or less within

91 m (299 ft) of any pinnacle trend feature with a vertical relief of 2 m (8 ft) or 

more.

(3) Live bottoms (low-relief features) are seagrass communities; areas that

contain biological assemblages consisting of sessile invertebrates living on and

attached to naturally occurring hard or rocky formations with rough, broken, or 

smooth topography; and areas where hard substrate and vertical relief may

favor the accumulation of sea turtles, fishes, or other fauna. No 

bottom-disturbing activities may cause impacts to live bottoms (low-relief 

features).

(4) Potentially sensitive biological features are features not protected by a 

biological lease stipulation that are of moderate to high relief (2 m [8 ft] or 

higher), provide surface area for the growth of sessile invertebrates, and attract 

large numbers of fish. No bottom-disturbing activities may cause impacts to 

potentially sensitive biological features.

The deepwater NTL 2009-G40 addresses features or areas that could support high-density 

chemosynthetic communities, deepwater corals, or other associated high-density hard bottom 

communities. Any proposed activities that could disturb the seafloor at water depths of >300 m 

(984 ft) must maintain a distance of at least 76 m (250 ft) between the location of the disturbance 

and any high-density hard bottom communities, and must maintain a distance of at least 610 m 

(2,000 ft) between those communities and the location for any proposed discharge of muds and 

cuttings. BOEM may modify these requirements on a case-by-case basis.

Avoidance and Reporting of Historic and Prehistoric Sites

BOEM and BSEE require site-specific information regarding potential archaeological 

resources prior to approving any G&G activities involving seafloor-disturbing activities or placement 

of bottom-founded equipment or structures in the AOI. BOEM and BSEE use this information to 

ensure that physical impacts to archaeological resources do not occur. 

All authorizations for G&G activities that involve seafloor-disturbing activities would include 

requirements for operators to report suspected historic and prehistoric archaeological resources to 

BOEM and BSEE, and take precautions to protect the resource. The requirements are in 

NTL 2005-G07 (“Archaeological Resource Surveys and Reports”), the enforcement for which is 

shared between BOEM and BSEE. BOEM and BSEE also require reporting and avoidance for any 

previously undiscovered, suspected archaeological resource as well as precautions to protect the 

resource from operational activities while appropriate mitigation measures are developed. 

Regulations have been promulgated based on the National Historic Preservation Act (NHPA) 

(16 U.S.C. §§ 470 et seq.), especially Sections 106 and 110; the Archaeological Resources 
B-12 Protective Measures and Mitigation and Regulatory Requirements

Protection Act of 1979 (16 U.S.C. § 470), which prohibits the excavation and removal of items of 

archaeological interest from Federal lands without a permit; and the Antiquities Act of 1906 

(16 U.S.C. § 431). Under the Oil and Gas Program regulations, archaeological resource surveys are 

required by 30 CFR §§ 550.203(o), 550.204(s), and 550.1007(a)(5), and an archaeological resource 

report is required by 30 CFR §§ 550.203(b)(15), 550.204(b)(8)(v)(A), and 550.1007(a)(5). These 

regulations are applicable to all G&G operations that involve seafloor-disturbing activities, including 

coring, grab sampling, and placement of ocean-bottom cables (OBCs) or ocean-bottom nodes 

(OBNs). Equivalent information needs to be provided for the Renewable Energy and Marine 

Minerals Programs, although equivalent regulations do not expressly exist for renewable energy or 

marine minerals, but these requirements are included as stipulation in non-competitive lease 

agreements within these programs. The equivalent is provided through guidance, supported by 

regulation and/or statutory authority (refer to NHPA Section 106, the OCSLA, and 30 CFR parts 585 

and 580).

If an operator discovers any archaeological resource while conducting operations authorized 

under a lease or pipeline right-of-way, operations that may affect the discovery must be halted 

immediately and the discovery reported to BOEM and BSEE. If BOEM determines that the resource 

is significant based on criteria under the NHPA, BSEE, in consultation with BOEM, will direct how 

the resource is to be protected during operations and activities. If BOEM determines that the 

resource is not significant, BOEM will so advise BSEE. The BSEE will inform the operator when 

operations may resume (30 CFR § 250.194).

Shallow Hazards Guidance

A portion of BOEM’s NTL 2008-G05 (“Guidance for Shallow Hazards Program”) applies to all 

G&G surveys performed. For any activities that involve seafloor-disturbing activities, in accordance 

with Section VI.B of the NTL, data must be collected to locate existing hazards.

1.2.1.4 Guidance for Military Coordination

The GOM is used extensively by the USDOD for conducting various mission operations, 

including air-to-air gunnery, rocket and missile research and testing, sonar buoy operations, pilot 

training, and aircraft carrier operations. These operations are conducted in 11 Military Warning 

Areas and 6 Eglin Water Test Areas located throughout the GOM (Figure 4.12-2 of this

Programmatic EIS). These areas are multiple-use areas where military operations and OCS 

exploration and development activities coexist. To ensure personnel safety and to reduce the 

likelihood of conflicts between military and OCS operations, NTL 2014-G04 (“Guidance for Activities 

In or Near Military Warning and Water Test Areas”) stipulates requirements in which the lessee or 

designated operator must enter into an agreement with the appropriate individual military command 

headquarters concerning the control of electromagnetic emissions and use of boats and aircraft in 

the applicable warning or water test area before commencing such traffic.
Gulf of Mexico G&G Activities Programmatic EIS B-13

1.2.2 Additional Mitigation for Oil and Gas Program Surveys

Additional mitigation measures specifically applicable to Oil and Gas Program surveys 

include (1) additional guidance for avoidance of archaeological resources, (2) additional shallow 

hazards guidance, and (3) guidance for conducting ancillary activities. A summary of these 

additional mitigation measures are provided in the following subsections.

1.2.2.1 Additional Avoidance of Historic and Prehistoric Sites

The additional measures required for seismic airgun surveys include NTL 2011-JOINT-G01 

(“Revisions to the List of OCS Lease Blocks Requiring Archaeological Resource Surveys and 

Reports”), which supersedes NTL 2008-G20 and provides additions to the list of OCS lease blocks 

that require archaeological resource surveys and reports to be submitted with plans, as well as the 

required line-spacing for each OCS lease block. In addition, site-specific, remote-sensing surveys of 

the seafloor are required when the information is deemed essential to making a reasonable 

determination of the presence of potentially significant resources. The required surveys are 

analyzed by industry and BOEM archaeologists prior to the authorization of any new or significant 

seafloor-disturbing impacts and, if necessary, avoidance of potential archaeological resources is 

prescribed. Archaeological surveys are expected to be highly effective in identifying resources to 

allow for the protection of the resource during permitted activities.

1.2.2.2 Additional Shallow Hazards Guidance

The remainder of NTL 2008-G05 (“Guidance for Shallow Hazards Program”) applies to 

seismic airgun surveys. The NTL provides guidance regarding shallow hazard reporting and survey 

requirements for exploration plans and Development Operations Coordination Documents (DOCDs), 

Applications to Drill, Platform Site Investigation Reports, and pipeline applications. In addition, the 

NTL (1) specifies the group intervals for acquiring medium-penetration seismic profiler information, 

(2) discontinues the process of obtaining prior approval if lessees or operators substitute 

three-dimensional (3D) data and information for HRG subbottom profiler information, (3) clarifies the 

procedures for submitting shallow hazards reports on compact disc-read only memory (CD-ROMs), 

(4) amends the format for listing magnetic anomalies and side-scan sonar contacts in shallow 

hazard reports, (5) clarifies that on-site provisions for mitigation of shallow hazards apply to lift and 

jack-up boats, and (6) allows a mobile offshore drilling unit (MODU) or other vessel to depart a 

location without fully raising its legs or mat as long as they are raised sufficiently to ensure no 

contact with pipelines or other potential hazards.

1.2.2.3 Guidance for Conducting Ancillary Activities

For ancillary G&G activities in depths >200 m (656 ft) or in the EPA at any water depth, as 

outlined in NTL 2009-G34 (“Guidance for Conducting Ancillary Activities”), operators must notify 

BOEM at least 30 days before a G&G exploration or development activity involving the use of an 

airgun or airgun array, independent of water depth, for any OBC, OBN, or time-lapse 

(four-dimensional [4D]) survey. Operators or lessees must notify BOEM through written notice at 

least 15 days prior to conducting any other ancillary G&G activity involving the use of airguns or 
B-14 Protective Measures and Mitigation and Regulatory Requirements

airgun arrays in water depths >200 m (656 ft), or in the EPA at any water depth, as well as any 

seafloor-disturbing activity (OBC, OBN, and time-lapse [4D] survey), or geotechnical surveys (piston, 

gravity, grab, or dredging), including retrieval of OBCs, anchors, or other equipment, independent of 

water depth. No notification to BOEM is required for ancillary activities that do not involve 

explosives, do not use airguns in water depths <200 m (656 ft) in the CPA and WPA, or do not 

disturb the seafloor.

1.2.3 Additional Mitigation for Renewable Energy Program Surveys

BOEM does not issue permits for or regulate the acquisition of geophysical data or 

geotechnical sampling on the OCS for renewable energy development. However, the results of such 

surveys and testing are required under BOEM’s renewable energy regulations at 30 CFR part 585 

for the submission of a Site Assessment Plan (SAP) (30 CFR § 585.610(b)), a Construction and 

Operations Plan (COP) (30 CFR § 585.626(a)), or a General Activities Plan (GAP) 

(30 CFR § 585.645(a)). Plans submitted to BOEM are required to describe hazards information and 

information pertinent to archaeological resources that could be affected by the activities proposed in 

an SAP (30 CFR §§ 585.611(a), (b)(1), and (b)(6)), COP (30 CFR §§ 585.627(a)(1) and (6)), and 

GAP (30 CFR §§ 585.646(a) and (f)). BOEM recommends following the guidelines to produce the 

data necessary to readily identify and/or characterize geological conditions, hazardous features, and 

cultural resources. If an applicant fails to provide the requested information, BOEM may not approve 

an SAP (30 CFR § 585.613(d)), COP (30 CFR § 585.628(e)), or GAP (30 CFR § 585.648(d)).

Elements of these guidelines may be required under the terms and conditions of a specific 

lease. A lease also may have requirements that are different from those discussed in these 

guidelines. Applicants are encouraged to have a pre-survey meeting with BOEM to discuss any 

proposed plan prior to initiation of survey activities. The guidance also provides recommendations 

for HRG surveys, including survey patterns (e.g., line spacing, site-specific, transmission cable 

routes); data acquisition equipment, including navigation, echosounders, side-scan sonar, and 

magnetometers (specific in that BOEM recommends these surveys be conducted below levels that 

cause Level A or B auditory impacts to marine mammals); and geotechnical testing.

1.2.4 Seismic Airgun Survey Protocol

The Seismic Airgun Survey Protocol (Attachment 1) specifies mitigation measures, 

including an exclusion zone, ramp-up requirements, visual monitoring by PSOs prior to and during 

seismic airgun surveys, and array shutdown requirements. The purpose of the protocol is to 

minimize the potential for injury to marine mammals (as defined in NTL 2016-BOEM-G02) and sea 

turtles and to avoid most Level A harassment of marine mammals.

The Seismic Airgun Survey Protocol is based on NTL 2016-BOEM-G02 (“Implementation of 

Seismic Survey Mitigation Measures and Protected Species Observer Program”). Each specific 

permit for seismic activities within the AOI will require additional analyses where BOEM may adjust 

mitigation based on the best available information at that time. The protocol provides the 

requirements applicable to all seismic airgun surveys for all alternatives evaluated in this 
Gulf of Mexico G&G Activities Programmatic EIS B-15

Programmatic EIS; however, additional mitigation measures are required for the various alternatives 

(i.e., Alternatives A through G). Additionally, Alternatives B through F expand the PSO Program 

portion of the protocol. Tables B-2 and 2.2-2 of this Programmatic EIS provide information 

regarding additional mitigation measures.

Although airguns have a frequency range from approximately 10 to 2,000 hertz (Hz), most 

acoustic energy is radiated at frequencies below 200 Hz. Acoustic pulses from airguns are within 

the hearing range of all marine mammals in the AOI (Appendix H, Section 3). The mysticete

species (e.g., Bryde’s whale) occurring in the AOI are low-frequency cetaceans (7 Hz to 22 kilohertz 

[kHz]), and most of the odontocetes are mid-frequency cetaceans (150 Hz to 160 kHz), with the 

exception of the Kogia species (i.e., pygmy sperm whale and dwarf sperm whale), which are 

high-frequency cetaceans (200 Hz to 180 kHz). Manatees have hearing capabilities similar to 

phocid pinnipeds (true seals), with functional hearing between approximately 250 Hz and 90 kHz. 

Airgun pulses are within the hearing range of sea turtles, whose best hearing is below 1,600 Hz 

(Appendix I, Section 3).

All authorizations for seismic airgun surveys (those involving airguns as an acoustic source) 

conducted in water depths >200 m (656 ft) in the WPA and CPA and in all water depths in the EPA

would include a survey protocol that specifies mitigation measures for protected species, including 

an exclusion zone, ramp-up requirements, visual monitoring by PSOs prior to and during seismic 

airgun surveys, and array shutdown requirements. The Seismic Airgun Survey Protocol specifies 

the conditions under which airgun arrays can be started and under which they must be shut down. It 

also includes the recommended but optional use of PAM to help detect vocalizing marine mammals. 

The protocol requirements apply specifically to airguns, not non-airgun HRG sources such as 

side-scan sonars; boomers, sparkers, and compressed high-intensity radiated pulse (CHIRP) 

subbottom profilers; and single-beam or multibeam echosounders that may be operating 

concurrently during seismic airgun surveys. Per NTL 2009-G34, no notification is required if airguns 

are used in water depths <200 m (656 ft) in the CPA and WPA.

1.2.4.1 Ramp-Up

Ramp-up (also known as “soft-start”) entails the gradual increase in intensity of an airgun 

array over a period of 20 minutes or more until maximum source levels are reached. The intent of 

ramp-up is to avoid or reduce the potential for instantaneous hearing damage to an animal (from the 

sudden initiation of an acoustic source at full power) that might be located in close proximity to an 

airgun array. Increasing sound levels are designed to warn animals of pending seismic operations 

and to allow sufficient time for animals to leave the immediate area. Increasing sound levels (e.g., 

from an airgun array) are thought to be annoying or aversive to marine mammals. Under optimal 

conditions, sensitive individuals are expected to move out of the area, beyond the range where 

hearing damage might occur. The procedural design and quantitative limits for ramp-up, however, 

are not based on rigid analytical or empirical evidence, and it is not certain if marine mammals 

interpret a survey ramp-up as a warning of a stressor to come, as a human might interpret. 
B-16 Protective Measures and Mitigation and Regulatory Requirements

Therefore, it is used mainly as a “common sense” procedure, although there is little information on 

its effectiveness (Weir and Dolman, 2007; Compton et al., 2007; Parsons et al., 2009).

Ramp-up has become a standard mitigation measure in the U.S. and worldwide. The 

International Association of Geophysical Contractors (2011) recommends ramp-up in its seismic 

survey guidelines. BOEM requires ramp-up procedures for seismic airgun surveys operating in the 

GOM.

1.2.4.2 Exclusion Zone

The Seismic Airgun Survey Protocol includes an exclusion zone (with a 500-m 

[1,640-ft] radius) centered on the acoustic source to minimize the potential for injury to marine 

mammals and sea turtles and to avoid Level A harassment of marine mammals to the maximum 

extent practicable. This exclusion zone applies specifically to airguns, not non-airgun HRG sources 

such as side-scan sonars; boomers, sparkers, and CHIRP subbottom profilers; and single-beam or 

multibeam echosounders that may be operating concurrently during seismic airgun surveys.

1.2.4.3 Exclusion Zone Monitoring by Protected Species Observers

The Seismic Airgun Survey Protocol includes visual monitoring of the exclusion zone by 

trained PSOs. At least two PSOs will be required on watch on board seismic vessels at all times 

during daylight hours (i.e., from approximately 30 minutes before sunrise to 30 minutes after sunset) 

when seismic operations are being conducted, unless conditions (e.g., fog, rain, and darkness) 

make sea-surface observations impossible. If conditions deteriorate during daylight hours such that 

sea-surface observations are halted, visual observations must resume as soon as conditions permit. 

Ongoing activities may continue but may not be initiated under such conditions (i.e., without 

appropriate pre-activity monitoring). Operators may engage third-party PSO members who have 

been trained as observers, or they may use a combination of third-party and trained crew observers. 

Training requirements are specified in NTL 2016-BOEM-G02 and currently include no minimum 

qualifications for PSO. However, qualifications were discussed in the 2013 National Standards for

Protected Species Observers (Baker et al., 2013) and may be required for future activities.

The PSOs are meant to monitor the exclusion zone for protected species and to observe and 

document the presence and behavior of protected species. The PSOs search the area around the 

vessel using high-powered, pedestal-mounted “Big Eye” binoculars; hand-held binoculars; and the 

unaided eye. For larger monitoring programs with a specified visual observation platform, two PSOs 

generally survey for protected species using high-powered binoculars. Established visual monitoring 

methods are effective but may not be foolproof in locating every marine mammal or sea turtle within 

the designated exclusion zone (Barkaszi et al., 2012). These mitigation methods rely on trained and 

experienced observers to conscientiously work to the required protocols. Data are recorded on 

paper sheets or a laptop computer that has direct input from the vessel’s global positioning system 

(GPS) navigation system. Observers rotate among the duty stations at regular intervals, and 

alternate work and rest periods based on a pre-determined schedule. In the event a marine 
Gulf of Mexico G&G Activities Programmatic EIS B-17

mammal or sea turtle is sighted or otherwise detected within the impact zone, seismic operations are 

suspended until the animal leaves the area (refer to Attachment 1).

Visual shipboard monitoring is affected by limitations on visibility of individuals due to poor 

visibility (e.g., fog, elevated Beaufort sea state, and nighttime operations), species detectability (e.g.,

cryptic species), and observer fatigue. Routine activities of marine mammals (e.g., diving duration 

patterns, pod size, and overt behaviors) show considerable variability among species, thereby 

affecting whether animals are sighted (i.e., availability bias). During nighttime operations or periods 

of reduced visibility, several options are available to allow for continual monitoring of the impact zone 

(e.g., shipboard lighting of waters around the vessel, use of enhanced vision equipment, night-vision 

equipment, and acoustic monitoring [active and passive]). However, the efficiency of visual 

monitoring during nighttime hours using shipboard lighting or enhanced vision equipment is limited 

compared with visual monitoring during daylight hours.

1.2.4.4 Shutdown Requirements

The Seismic Airgun Survey Protocol requires shutdown of the airgun array any time certain

marine mammals or sea turtles are observed within the exclusion zone, whether due to the animal’s 

movement, the vessel’s movement, or because the animal surfaced inside the exclusion zone for 

seismic airgun surveys performed in water depths >200 m (656 ft) in the CPA and WPA and for all 

seismic airgun surveys performed in the EPA. In the event of a shutdown, operations and ramp-up 

of equipment would recommence only when the sighted animal has cleared the exclusion zone and 

no other marine mammals or sea turtles have been sighted within the exclusion zone for the 

required time specified in the protocols. Shutdown would not be required for manatees and marine 

mammals in the Family Delphinidae (this includes, among others, killer whales, pilot whales, and all 

of the “dolphin” species) approaching the vessel (or vessel’s towed equipment). After a shutdown, 

the operator may recommence seismic operations with a ramp-up of airguns only when the 

exclusion zone has been visually inspected for at least 30 minutes to help ensure the absence of all 

marine mammals and sea turtles.

1.2.4.5 Passive Acoustic Monitoring

The Seismic Airgun Survey Protocol strongly encourages, but does not require, the use of 

PAM during monitoring of the exclusion zone when visual observations cannot be used (times of 

reduced visibility) (refer to Attachment 1). This provision is included in NTL 2016-BOEM-G02 

(“Implementation of Seismic Survey Mitigation Measures and Protected Species Observer 

Program”). Under the Settlement Agreement, PAM is required during all nighttime and non-visual 

operations. During low-visibility conditions, PAM can be used to allow ramp-up when it would 

otherwise not be allowed. Regulations regarding the use of PAM during geophysical surveys vary in 

other parts of the world and range from no PAM recommendations to requiring PAM at all times 

during the survey (Weir and Dolman, 2007; Compton et al., 2007; Nowecek et al., 2013; Wright and 

Cosentino, 2015). Marine mammals are at the greatest risk of potential injury from seismic airguns 

when they are submerged and within proximity of the airgun array. Visual monitoring methods are 

not fully effective for detecting the presence of submerged animals or for detecting surfaced animals 
B-18 Protective Measures and Mitigation and Regulatory Requirements

at night and during periods of high sea state and poor visibility. In some cases, PAM may serve as 

an effective tool for detecting submerged vocalizing marine mammals when they are not detectable 

by visual observation (Hedgeland et al., 2012). Inclusion of PAM does not relieve an operator of any 

of the mitigations (including visual observations) in the Seismic Airgun Survey Protocol with the 

following exception: use of PAM will allow ramp-up and the subsequent start of a seismic survey 

during times of reduced visibility (e.g., darkness, fog, and rain) when it otherwise would not be 

permitted using only visual observers.

There are two types of PAM systems commonly used for marine mammal detection: fixed 

systems and towed systems. Fixed PAM systems can monitor underwater sounds over a wide 

range of spatial and temporal scales but are rarely used in real-time mitigation during geophysical 

surveys. There are three categories of fixed systems: autonomous recorders; radio-linked 

hydrophone systems; and fixed cable hydrophone systems. Autonomous recorders acquire and 

store acoustic data internally and are deployed semi-permanently underwater via a mooring or buoy 

and must be retrieved to access the data. These recorders are capable of continuous recording, 

automatic detection/classification of sounds, and collection of non-acoustic data. Radio-linked 

hydrophone systems consist of hydrophones that are moored or fixed to the seafloor and transmit 

audio signals via radio waves to a receiving station onshore. Fixed cable hydrophone systems 

typically are located on the seafloor in a permanent configuration and can continuously send data to 

a receiving station. Fixed PAM systems often are used for the monitoring of marine mammals and 

the acoustic environment prior to an activity at a fixed location (Bingham, 2011). For example, the 

U.S. Navy uses a fixed PAM system to monitor their test ranges over long periods of time to 

determine species abundances and distribution prior to activities that may impact these species.

Towed PAM systems often are used for real-time mitigation during seismic surveys because 

they maintain the surveillance area around the moving vessel and airgun sources. The basic 

configuration of towed PAM systems has not changed significantly since its early implementation as 

a mitigation tool. Towed systems consist of a hydrophone array, tow cable, deck cable, and data 

processing and monitoring system that processes, displays, and stores selected data. Tow lengths, 

depths, and positions depend on the vessel and its airgun and streamer configuration; however, the 

PAM hydrophone cable usually is independent from any other vessel systems and is towed 200 to 

300 m (656 to 984 ft) behind the survey vessel. Exceptions to this configuration are the 

streamer-integrated PAM systems in which designated marine mammal hydrophones are embedded 

into the vessel’s seismic streamer arrays. The data transmission and processing remain similar 

between independent and integrated PAM systems. Hydrophone signals are processed for output to 

the operator with specialized pre-loaded software designed to detect marine mammal impulsive and 

tonal vocalizations (Hedgeland et al., 2012). Towed arrays have the advantage of mobility and large 

spatial coverage, and therefore can be used for monitoring when the acoustic source is mobile or 

covering a large area. However, these systems have limited directional capabilities and face

challenges from sound source masking and localization of fast-moving species. They also have 

limitations from ship availability, can be readily damaged, can interfere with seismic equipment if not 

deployed correctly, and do not provide accurate detection in front of the vessel. Some of these 

limitations can be overcome, and new technology is being developed (e.g., beam-forming arrays that 
Gulf of Mexico G&G Activities Programmatic EIS B-19

enhance low signal-to-noise ratios, marine mammal call detection in chosen “look directions,” and 

vector sensors that can measure angles from a single point and assist with determining a more 

precise bearing of the animal) (Bingham, 2011). Every installation must be designed on a 

case-by-case basis given the requirements, environment, and resources available. The system’s 

performance goals (e.g., detection, classification, and localization) will need to consider the 

technological and operational limitations to determine the best method for PAM utilization.

The PAM software and hardware technologies that currently exist can perform many marine 

mammal monitoring and mitigation requirements under a wide range of operational conditions. 

However, no single technical approach has the ability to satisfy all or even most of the marine 

mammal monitoring and mitigation requirements of the offshore industry, and an integrated 

approach is most likely necessary. In order to be effective for mitigation, the PAM system and 

operator must be able to detect, classify, and localize an animal very rapidly. This presents 

limitations in that PAM works only if the animals produce sound that can be detected by the system; 

there are cryptic species of marine mammals that do not vocalize much or at all, and there are 

different propagation properties for each species’ vocal characteristics, making some easier to

detect. Additionally, PAM operators must be trained and experienced in order to successfully deploy 

and operate the PAM systems, even with the advancement of auto-detection software capabilities. 

Although the technology for detecting and locating underwater sounds and their sources is well 

developed, integrated hardware and software systems specifically designed to locate and track 

marine mammals as mitigation for seismic airgun surveys are not fully mature and continue to be 

developed for commercial applications.

1.2.4.6 Summary of Visual Observer Requirements

Several of the preceding sections described requirements for PSOs or other observers. 

Requirements for observers are summarized in Table B-3. All G&G operators must comply with 

guidance for vessel strike avoidance as explained in Chapter 2 of this Programmatic EIS. 

Regardless of the type of G&G survey being conducted, visual observers monitoring solely for 

vessel strike avoidance can be trained crew members or third-party observers. Visual observers do 

not have specific training requirements nor will they need to be approved by BOEM or BSEE.

All seismic airgun surveys must use PSOs to monitor the exclusion zone. A PSO for a 

seismic airgun survey must have completed a PSO training course as specified in 

NTL 2016-BOEM-G02.
B-20 Protective Measures and Mitigation and Regulatory Requirements

Table B-3. Observer Requirements for G&G Survey Types. 

Survey Type PSO Required?

PSO Affiliation 

(Third Party, 

Crew, or 

Combination)

PSO Watch Requirements

Number of PSOs 

on Duty when 

Acoustic Sources 

Operating

Total Number of 

PSOs on Board Vessel Strike Avoidance

Seismic airgun 

survey with no 

PAM 

Yes1 Third party, 

crew, or 

combination 

1. Other than brief alerts to bridge 

personnel of maritime hazards, no 

additional duties during watch. 

2. A watch must be no longer than 

4 consecutive hours. 

3. A break of at least 2 hours must

occur between 4-hour watches, 

with no other duties during this 

period. 

4. A PSO’s combined watch 

schedule must not exceed 

12 hours in a 24-hour period.

2 visual PSOs 

(daylight only)

At least 3 (based 

on watch 

requirements)

• Handled by PSOs when 

airguns are operating. 

• When vessel is in 

transit or other times 

when airguns not 

operating, could be 

done by PSO or crew 

member.

Seismic airgun 

survey with PAM Yes1 Third party, 

crew, or 

combination 

Same as above

2 visual PSOs 

(daylight only); 

1 PAM operator

At least 4 based 

on watch 

requirements; 

3 visual PSOs 

plus PAM 

operator(s))

Same as above

Non-airgun HRG 

survey with 

exclusion zone 

Yes

Third party, 

crew, or 

combination 

Same as above 1 visual PSO 

(daylight only)

At least 2 (based 

on watch 

requirements)

• Handled by PSOs when 

acoustic sources are 

operating. 

• When vessel is in transit 

or other times when 

acoustic source are not 

operating, could be 

done by PSO or other 

crew member.

HRG survey with 

no exclusion 

zone (all 

frequencies

>200 kHz) 

No N/A N/A None None

Handled by crew member 

as part of navigational 

duties.

Other G&G 

surveys

No N/A N/A None None

Handled by crew member 

as part of navigational 

duties.

G&G = geological and geophysical; kHz = kilohertz; N/A = not applicable; PAM = passive acoustic monitoring; PSO = protected species observer.

1 A PSO for a seismic airgun survey is someone who has successfully completed an approved PSO training course.
Gulf of Mexico G&G Activities Programmatic EIS B-21

1.3 ADDITIONAL PROTECTIVE MEASURES INCLUDED IN THE ALTERNATIVES

The mitigation measures, as discussed in Chapter 2 of this Programmatic EIS, that would 

apply to all alternatives include the following: 

• guidance for vessel strike avoidance;

• guidance for marine debris awareness;

• avoidance of sensitive benthic resources;

• regulations for activities in or near NMSs; 

• guidance for avoidance of historic and prehistoric sites; and

• guidance for military coordination.

Additional mitigation measures are included in Alternatives B through G and are listed below, 

and their applicability to G&G survey types are identified in Table B-2 and described in 

Sections 1.3.1 through 1.3.8: 

• mitigation for non-airgun HRG surveys, including a Non-Airgun HRG Survey 

Protocol with use of PSOs;

• expanded PSO Program; 

• minimum separation of concurrent seismic surveys; 

• reduced level of activity;

• a Seismic Airgun Survey Protocol with required use of PAM; 

• coastal waters seasonal restrictions; and

• area closures for seismic airgun surveys.

1.3.1 Non-Airgun HRG Survey Protocol

The purpose of the Non-Airgun HRG Survey Protocol is to reduce the potential for acoustic 

impacts to marine mammals and sea turtles due to active acoustic sources. Based on the 

information included in Appendices H and I, acoustic sources operating at frequencies >200 kHz 

are not likely to be within the hearing range of marine mammals or sea turtles. Therefore, there is 

no need to implement the additional mitigation requirements for such surveys.

For non-airgun HRG surveys using sources operating at and below 200 kHz, the 

implementation of the Non-Airgun HRG Survey Protocol is required to minimize the potential for 

injury to marine mammals and sea turtles and avoid most Level A harassment of marine mammals. 

Ramp-up is not expected to be an effective mitigation measure for non-airgun HRG surveys because 

electromechanical sources typically are on or off and are not powered up gradually.
B-22 Protective Measures and Mitigation and Regulatory Requirements

The Non-Airgun HRG Survey Protocol is included in Alternatives C through F, depending on 

the operating frequencies of the non-airgun HRG surveys. The Non-Airgun HRG Survey Protocol is 

for surveys that use only acoustic sources such as side-scan sonar; boomers, sparkers, and CHIRP 

subbottom profilers; and single-beam and multibeam echosounders. HRG surveys using airguns 

operating concurrently with non-airgun sources would be subject to the Seismic Airgun Survey 

Protocol described in Attachment 1. 

Mitigation applicable to non-airgun HRG surveys is specified in the Non-Airgun HRG Survey 

Protocol (refer to Attachment 2). In reviewing each specific application for non-airgun HRG 

surveys, BOEM will use the site-specific review to adjust mitigation based on the best available 

information at that time. The Non-Airgun HRG Survey Protocol requirements can be summarized as 

follows:

• All non-airgun HRG operators must comply with separate guidance for vessel 

strike avoidance, marine debris awareness, avoidance of sensitive seafloor 

resources, activities in or near NMSs, and military coordination.

• If non-airgun HRG sources will operate above 200 kHz, no additional mitigations 

are required.

• Non-airgun HRG surveys in which one or more active acoustic sources will be 

operating at frequencies at or below 200 kHz, a pre-survey clearance period (of 

marine mammals and sea turtles) of 30 minutes before start-up or after a 

shutdown for any sperm, Bryde’s, beaked, or Kogia whale(s) or manatee(s) that 

are within the exclusion zone. 

• One PSO and 200-m (656-ft) exclusion zone monitoring for non-airgun HRG 

surveys in all water depths throughout the GOM operating at or below 200 kHz.

• If seismic airguns are used for HRG surveys, these surveys would be subject to 

the Seismic Airgun Survey Protocol.

1.3.1.1 Exclusion Zone

For non-airgun HRG surveys in which at least one acoustic source will operate at or below 

200 kHz, the Non-Airgun HRG Survey Protocol would establish a 200-m (656-ft) exclusion zone, 

require visual monitoring by trained PSOs, and specify start-up and shutdown requirements. The 

exclusion zone applies specifically to non-airgun HRG sources such as side-scan sonar; boomers, 

sparkers, and CHIRP subbottom profilers; and single-beam or multibeam echosounders.

1.3.1.2 Exclusion Zone Monitoring by Protected Species Observers

All non-airgun HRG surveys using one or more acoustic sources operating at or below 

200 kHz must use trained PSOs to monitor a 200-m (656-ft) exclusion zone for a pre-survey 

clearance period, 30 minutes, for all marine mammals and sea turtles in all water depths throughout 
Gulf of Mexico G&G Activities Programmatic EIS B-23

the GOM. If there are no acoustic sources operating at frequencies ≤200 kHz, there will be no 

exclusion zone and no requirements for PSOs or other trained visual observers.

A PSO for a non-airgun HRG survey is defined as someone who has successfully completed 

a PSO training course. The PSOs can be trained crew members or third-party observers. Basic 

training criteria have been established and must be adhered to by any entity that offers PSO training. 

BOEM will not sanction particular trainers or training programs.

Visual monitoring of the exclusion zone must be conducted by trained PSOs. At least one 

PSO would be required on watch on board non-airgun HRG survey vessels at all times during 

daylight hours (i.e., from approximately 30 minutes before sunrise to 30 minutes after sunset) when 

survey operations are being conducted, unless conditions make sea surface observations 

impossible (e.g., fog, rain, and darkness). If conditions deteriorate during daylight hours such that 

the sea surface observations are halted, visual observations must resume as soon as conditions 

permit. Ongoing activities may continue but may not be initiated under such conditions (i.e., without 

appropriate pre-activity monitoring). 

Requirements for PSO observers are summarized in Table B-3. All G&G operators must 

comply with guidance for vessel strike avoidance as explained in Chapter 2 of this Programmatic 

EIS. Regardless of the type of G&G survey being conducted, visual observers monitoring solely for 

vessel strike avoidance can be crew members or trained third-party observers. They do not have 

specific training requirements nor will they need to be approved by BOEM or BSEE.

1.3.1.3 Shutdown Requirements

Monitoring of the exclusion zone would begin no less than 30 minutes prior to start-up and 

continue until operations cease. Immediate shutdown of the non-airgun HRG source(s) must occur 

if any sperm, Bryde’s, beaked, or Kogia whale(s) or manatee(s) are detected entering or within the 

exclusion zone. After a shutdown, subsequent restart of non-airgun HRG operations may only occur 

following confirmation that the exclusion zone is clear of all marine mammals and sea turtles for 

30 minutes. 

1.3.2 Expanded PSO Program

An expanded PSO Program is included in Alternatives B through F. For Alternatives B, C, E, 

and F, the expanded PSO Program is applicable to all seismic airgun surveys in all water depths and 

requires shutdown of the airgun array any time a marine mammal (excluding marine mammal 

species in the Family Delphinidae, which includes killer whales, pilot whales, and all of the dolphin 

species), including manatees, is observed within the exclusion zone, whether due to the animal’s 

movement, the vessel’s movement, or because the animal surfaced inside the exclusion zone for all 

deep-penetration seismic airgun surveys performed in the GOM, regardless of water depth. In the 

event of a shutdown, operations and ramp-up of equipment would recommence only when the 

sighted animal has cleared the exclusion zone and no other marine mammals or sea turtles have 

been sighted within the exclusion zone for the required time specified in the protocols. After a 
B-24 Protective Measures and Mitigation and Regulatory Requirements

shutdown, the operator may recommence seismic operations with a ramp-up of airguns only when 

the exclusion zone has been visually inspected for at least 30 minutes to help ensure the absence of 

all marine mammals and sea turtles.

For Alternative D, the above would apply; however, shutdown would not be required for 

dolphins actively approaching the vessel (or the vessel’s towed equipment) for the purposes of 

bow-riding. In the GOM, species known to bow-ride include bottlenose, Fraser’s, Clymene’s, 

rough-toothed, striped, spinner, Atlantic spotted, pantropical, and Risso’s dolphins.

Although there are no minimum qualification requirements for PSOs, for Alternatives C 

through F, the qualifications discussed in the 2013 National Standards for Protected Species 

Observers (Baker et al., 2013) may be required for future activities. These qualifications may 

include the following:

• a bachelor’s degree from an accredited college or university with a major in one 

of the natural sciences and a minimum of 30 semester hours or equivalent in the 

biological sciences;

• at least one undergraduate course in math or statistics;

• experience with data entry on computers;

• satisfactory completion of a NMFS-approved PSO training course;

• be in good health and have no physical impairments that would prevent 

performing assigned tasks;

• able to clearly and concisely communicate verbally and in writing in English; and

• be a U.S. citizen, or a non-citizen who has a green card, TN authorization, 

H1 visa, or valid work visa, and a Social Security card.

1.3.3 Geographic Separation Between Simultaneous Seismic Airgun Surveys

Alternative B would establish a 40-km (25-mi) geographic separation distance between 

simultaneously operating deep-penetration seismic airgun surveys performed in the designated 

Areas of Concern (Figure B-2). For deep-penetration seismic airgun surveys performed outside the 

Areas of Concern, a 30-km (18.6-mi) geographic separation distance between simultaneously 

operating seismic airguns would be required. Additionally, the separation distance would apply 

within a 5-km (3-mi) buffer zone adjacent to and seaward of the 20-m (66-ft) isobath and to the 

Areas of Concern that fall within the EPA.
Gulf of Mexico G&G Activities Programmatic EIS B-25

Figure B-2. Alternative B Seasonal Restrictions for Coastal Waters and Other Closure Areas (as 

defined in the Amended Settlement Agreement as the Areas of Concern).

1.3.4 Reduced Level of Activity

In Alternative E, BOEM would authorize a reduced level of activity. Alternative E has two 

options: Alternative E1 specifies a reduction of deep-penetration seismic airgun surveys (in line 

miles) by 10 percent from the estimated levels in a calendar year (Table 2.7-1 of this Programmatic 

EIS); and Alternative E2 specifies a reduction of deep-penetration seismic airgun surveys (in line 

miles) by 25 percent from the estimated levels in a calendar year (Table 2.7-2 of this Programmatic 

EIS).

Activities could be conducted in any of the GOM planning areas. When the maximum 

exploration survey activities are authorized, no additional authorization of activities for airgun 

exploration would be issued for the remainder of the calendar year. Any specific method of 

implementation may be specified further through a NTL or other guidance.

1.3.5 Use of PAM Required

Under Alternatives B through F, the use of PAM would be required as part of the Seismic 

Airgun Survey Protocol (rather than optional or “encouraged” as in Alternative A) for all surveys 

occurring during periods of reduced visibility in water depths >100 m (328 ft). The purpose would be 

to improve detection of marine mammals prior to and during seismic airgun surveys so that impacts 
B-26 Protective Measures and Mitigation and Regulatory Requirements

can be avoided by shutting down or delaying start-up of airgun arrays until the animals are outside 

the exclusion zone. Note: Some operators voluntarily implemented PAM prior to the 2013 

Settlement Agreement conditions.

Under Alternatives C through F, the use of PAM would be required as part of the Seismic 

Airgun Survey Protocol (rather than optional or “encouraged” as in Alternative A) for all 

deep-penetration seismic airgun surveys at all times in the Mississippi Canyon and De Soto Canyon 

lease blocks. The purpose would be to improve detection of marine mammals prior to and during 

deep-penetration seismic airgun surveys so that impacts can be avoided by shutting down or 

delaying start-up of airgun arrays until the animals are outside the exclusion zone. Overall, the 

requirement for PAM in the canyon lease blocks will reduce the potential for Level A exposures to 

marine mammals, including Bryde’s whales and ESA-listed sperm whales. 

The proposed methodology for implementing a PAM survey will require BOEM approval. 

Survey and sighting reports must include, at a minimum, information specified in the protocol. A 

description of the PAM system, the software used, and the Monitoring Plan must be provided to 

BOEM prior to the survey. An assessment of the usefulness, effectiveness, and problems 

encountered with the use of PAM as a method of marine mammal detection must be provided after 

the survey. 

1.3.6 Coastal Water Seasonal Restrictions

Alternative B includes a seasonal restriction for airgun surveys in Federal coastal waters 

from (1) March 1 to April 30 in Federal coastal waters shoreward of the 20-m (66-ft) isobath (and a 

5-km [3-mi] buffer extending seaward from the 20-m [66-ft] isobath) and (2) from January 1 to 

April 30 within the portion of these coastal waters falling within the boundaries of the Unusual 

Mortality Event in the northern GOM (Figure B-2, Areas of Concern Polygon 3). This means that no 

seismic airgun surveys can be performed in these coastal waters during the time frame identified. 

Alternatives C through F include a seasonal restriction for airgun surveys for all coastal 

waters (Federal and State) shoreward of the 20-m (66-ft) isobath between February 1 and May 31

(Figure B-3). This means that no seismic airgun surveys can be performed in these coastal waters 

during the time frame identified.
Gulf of Mexico G&G Activities Programmatic EIS B-27

Figure B-3. Coastal Seasonal Restriction Area (Federal and State waters) Between February 1 and 

May 31 and Areas Requiring Passive Acoustic Monitoring for All Seismic Airgun Surveys for 

Alternatives C Through F.

1.3.7 Area Closures

Alternatives B and F include closure areas where no new deep-penetration seismic airgun 

surveys can be performed. Alternative B restricts deep-penetration seismic airgun surveys within 

the Areas of Concern that fall within the EPA and within the 5-km (3-mi) buffer zone adjacent to 

portions of Areas of Concern 2 and 4 (Figure B-2). This restriction does not apply to currently 

leased OCS blocks, any portion of the area encompassed by EPA Lease Sale 226, or neighboring 

OCS lease blocks adjacent to permitted survey areas but within an otherwise off-limit area.

Alternative F restricts all new seismic airgun surveys and non-airgun HRG surveys with 

equipment operating at or below 200 kHz within the EPA, CPA, Flower Gardens, and Dry Tortugas 

Closure Areas (Figure B-4). Non-airgun HRG surveys with equipment operating at frequencies 

>200 kHz are permitted in these areas. All existing authorized G&G activities in the closure areas 

would continue to occur in accordance with the existing permit or authorization. In addition, airgun 

surveys conducted outside of the closure areas would be required to remain at a distance such that 

received sound levels at the closed area boundaries would not exceed the threshold for Level B 

harassment (currently 160 decibels referenced to 1 micropascal [dB re 1 μPa]), as determined by 

field verification of sound levels or sound field modeling.
B-28 Protective Measures and Mitigation and Regulatory Requirements

Figure B-4. Alternative F Closure Areas (i.e., the Central Planning Area Closure Area, Eastern 

Planning Area Closure Area, Dry Tortugas Closure Area, and Flower Gardens Closure 

Area) and Seasonal Restrictions for Coastal Waters Between February 1 and May 31 and 

Areas Requiring Passive Acoustic Monitoring for All Seismic Airgun Surveys.

1.3.8 Areas with Additional Restrictions

Alternative B identifies some areas that include additional mitigation measures not previously 

discussed, including the following: 

• When surveying OCS lease blocks neighboring the Areas of Concern, including 

the 5-km (3-mi) buffer zone, that fall within the EPA, the operators must, in both 

planning and conducting a survey, limit the active use of airguns in OCS lease 

blocks that are adjacent to the Areas of Concern that fall within the EPA

(Figure B-2). Neighboring OCS lease blocks include those located two lease 

blocks adjacent in any direction from the area being surveyed; and

• Additional G&G survey application requirements submitted to BOEM include:

− The applicant must provide confirmation of lowest sound source and survey 

non-duplicity by the following:

• Written justification explaining why the proposed deep-penetration 

seismic airgun survey is not unnecessarily duplicative of previously 

conducted surveys; and 
Gulf of Mexico G&G Activities Programmatic EIS B-29

• An estimate of total energy output per impulse in decibels (root mean 

square [rms]) with respect to each energy source to be used and verify in 

writing that the airgun arrays, to the furthest extent practicable, use the 

lowest sound intensity level that still achieves the survey’s goals.

2 FEDERAL REGULATIONS AND AGENCIES

2.1 FEDERAL REGULATIONS

2.1.1 National Environmental Policy Act

Signed into law on January 1, 1970, NEPA was the first major environmental law in the U.S. 

and established the country’s national environmental policies. Implementation of NEPA policies 

occurs through an environmental impact assessment process. Under NEPA, all Federal agencies 

are required to use a systematic, interdisciplinary approach to protect the human environment and to 

ensure the integrated use of the natural and social sciences in any planning and decisionmaking that 

may have an impact on the environment.

In 1979, the CEQ established uniform guidelines for implementing the procedural provisions 

of NEPA. These regulations (40 CFR parts 1500 through 1508) provide for the use of the NEPA 

process to identify and assess reasonable alternatives to a proposed action that avoid or mitigate 

adverse effects of a given action upon the quality of the human environment. The USDOI 

regulations to implement NEPA can be found in 43 CFR part 46.

Under NEPA, a detailed EIS must be prepared for major Federal actions that may have a 

significant impact on the environment. The EIS will fully discuss significant environmental impacts 

and inform decisionmakers and the public of reasonable alternatives. In addition, the EIS must 

address any adverse environmental effects that cannot be avoided or mitigated, alternatives to the 

proposed action, the relationship between short-term uses and long-term productivity of the 

environment, and any irreversible and irretrievable commitments of resources involved in the 

proposed action. The NEPA requirement for analysis of major Federal actions is the underlying 

driver for the production of this Programmatic EIS.

The USDOI Implementation of NEPA’s Final Rule (43 CFR part 46) establishes procedures 

for the Department and its constituent bureaus to use for compliance with NEPA and the CEQ 

regulations for implementing NEPA. The Final Rule supplements, and is to be used in conjunction 

with, the CEQ regulations except where it is inconsistent with other statutory requirements.

The USDOI has implementing guidelines that provide agency direction in the application of 

NEPA. These guidelines include USDOI Departmental Manual Part 516, Chapter 15, which outlines 

the basic guidelines for implementing NEPA. It delineates NEPA responsibilities within the USDOI, 

provides guidance to applicants, defines major actions normally requiring an EIS, and identifies 

actions that have been designated as categorical exclusions (CATEXs).
B-30 Protective Measures and Mitigation and Regulatory Requirements

The USDOI’s Environmental Memoranda Series addresses Department environmental 

responsibilities in three areas: compliance, review, and statement. The Environmental Compliance 

Memoranda Series provides guidance to bureaus and agencies of the USDOI to ensure compliance 

with pollution control and environmental protection statutes. The Environmental Review Memoranda 

Series furnishes information and guidance concerning the receipt, distribution, coordination, and 

conduct of environmental project reviews requested by other agencies. The Environmental 

Statement Memoranda Series provides complementary information and guidance to bureaus and 

offices of the USDOI to ensure compliance with NEPA. The NEPA compliance follows this order of 

precedence: (1) CEQ regulations; (2) USDOI regulations (43 CFR part 46); (3) USDOI policy 

(Departmental Manual Part 516); and (4) USDOI guidance provided in the Environmental 

Memoranda Series.

Since the issuance of an Incidental Take Authorization (ITA) would allow for the taking of 

marine mammals, consistent with the provisions under the MMPA and incidental to the G&G 

activities, the National Oceanic and Atmospheric Administration (NOAA) considers this issuance to 

be a major Federal action subject to NEPA. Therefore, NOAA’s National Marine Fisheries Service 

intends to adopt this Programmatic EIS as the NEPA documentation associated with authorizing 

incidental take of marine mammals. In addition, NMFS and the Office of National Marine 

Sanctuaries (ONMS) may rely on the analysis within this Programmatic EIS to support consultation 

efforts under the ESA, Magnuson-Stevens Fishery Conservation and Management Act (MSFCMA) 

and National Marine Sanctuaries Act (NMSA). 

2.1.2 Outer Continental Shelf Lands Act

The OCSLA of 1953 (43 U.S.C. §§ 1331 et seq.), as amended, established federal 

jurisdiction over submerged lands on the OCS seaward of State boundaries (which were defined in 

the Submerged Lands Act of 1953). The OCSLA provides guidelines for implementing an OCS oil 

and gas exploration and development program. The basic goals of the OCSLA include the following:

(1) establish policies and procedures for managing the oil and natural gas 

resources of the OCS that are intended to result in expedited exploration and 

development of the OCS in order to achieve national economic and energy 

policy goals, assure national security, reduce dependence on foreign sources, 

and maintain a favorable balance of payments in world trade;

(2) preserve, protect, and develop oil and natural gas resources of the OCS in a 

manner that is consistent with the need to (a) make such resources available to 

meet the Nation’s energy needs as rapidly as possible; (b) balance orderly 

resource development with protection of the human, marine, and coastal 

environments; (c) ensure the public a fair and equitable return on the resources 

of the OCS; and (d) preserve and maintain free enterprise competition;
Gulf of Mexico G&G Activities Programmatic EIS B-31

(3) encourage development of new and improved technology for energy resource 

production, which will eliminate or minimize risk of damage to the human, 

marine, and coastal environments; and

(4) ensure that affected States and local governments have timely access to 

information regarding OCS activities and opportunities to review, comment, and 

participate in policy and planning decisions.

Under the OCSLA, the Secretary of the Interior is responsible for the administration of 

mineral exploration and development of the OCS. Within the USDOI, the Bureau of Ocean Energy 

Management is charged with the responsibility of managing and regulating the development of OCS 

oil and gas resources in accordance with the provisions of the OCSLA.

The Energy Policy Act (EPAct) of 2005 (Public Law [P.L.] 109-58) added Section 8(p)(1)(C) 

to the OCSLA, granting the Secretary of the Interior the authority to issue leases, easements, or 

rights-of-way on the OCS for the purpose of renewable energy development 

(43 U.S.C. § 1337(p)(1)(C)). Under the OCSLA, the Bureau of Ocean Energy Management also has 

jurisdiction over certain geophysical (e.g., seismic, side-scan sonar, bathymetric, and 

magnetometer) surveying and geological (e.g., vibracoring, boring, and grab sampling) sampling 

activities that occur in support of the exploration and development of energy and mineral resources 

on the OCS. BOEM has no jurisdiction over these activities in State waters.

Section 11(a)(1) of the OCSLA states that, “[A]ny agency of the United States and any 

person authorized by the Secretary of the Interior may conduct geological and geophysical 

explorations in the outer Continental Shelf, which do not interfere with or endanger actual operations 

under any lease maintained or granted pursuant to this Act, and which are not unduly harmful to 

aquatic life in such area.” Section 11(a)(2) further provides, “The provisions of paragraph (1) of this 

subsection will not apply to any person conducting explorations pursuant to an approved exploration 

plan on any area under lease to such person pursuant to the provisions of the OCSLA.”

Section 11(g) specifies that permits for geological explorations must be issued only if the 

Secretary of the Interior determines that “such exploration will not be unduly harmful to aquatic life in 

the area....” BOEM’s regulations at 30 CFR § 551.6 state that permit holders for G&G activities 

must not “cause harm or damage to life (including fish and other aquatic life), property, or to the 

marine, coastal, or human environment.”

Section 20 of the OCSLA states the Secretary of the Interior will “. . . conduct such additional 

studies to establish environmental information as he deems necessary and will monitor the human, 

marine, and coastal environments of such area or region in a manner designed to provide timeseries and data trend information which can be used for comparison with any previously collected 

data for the purpose of identifying any significant changes in the quality and productivity of such 

environments, for establishing trends in the area studied and monitored, and for designing 

experiments to identify the causes of such changes.” BOEM’s Environmental Assessment Section is 
B-32 Protective Measures and Mitigation and Regulatory Requirements

responsible for conducting analyses, such as this Programmatic EIS, to assess the environmental 

impacts of OCS Program activities, involve all stakeholders in the process, and inform the public.

Federal jurisdiction for renewable energy facilities on the OCS was established by Section 8 

of the EPAct. In addition to providing the authority to issue leases, easements, and rights-of-way, 

the EPAct includes a requirement that any activity authorized under this authority be carried out in a 

manner that provides for various factors, including the following:

• safety;

• protection of the environment;

• prevention of waste; 

• conservation of the natural resources of the OCS; 

• prevention of interference with reasonable uses of the Exclusive Economic Zone, 

the high seas, and the territorial seas; 

• consideration of any other use of the sea or seafloor, including use for a fishery, 

a sea lane, a deepwater port, or navigation;

• public notice and comment on any proposal submitted for a lease, easement, or 

right-of-way; and 

• oversight, inspection, research, monitoring, and enforcement relating to a lease, 

easement, or right-of-way.

On April 22, 2009, BOEM promulgated final regulations implementing this authority at 

30 CFR part 585. The USDOI is required to manage the leasing, site assessment, installation, and 

production of renewable energy on the Federal OCS. Certain G&G surveys are required to 

characterize seafloor conditions before installing a renewable energy facility or to verify completion 

of decommissioning activities. Under the renewable energy regulations, after a lease is issued, the 

lessee may not commence construction of meteorological or other site assessment facilities until a 

Site Assessment Plan and the site characterization survey reports are submitted to and reviewed by 

BOEM (30 CFR §§ 585.605-618). The lessee’s Site Assessment Plan must contain a description of 

environmental protection features or measures that the lessee will use. Similarly, when a grant is 

made for a right-of-way, or right-of-use and easement, the grantee may not commence construction 

or perform other site assessment activities until a General Activities Plan and site characterization 

survey reports are submitted to and reviewed by BOEM (30 CFR §§ 285.645-648).

BOEM has developed guidelines for providing G&G, hazards, and archaeological information 

pursuant to 30 CFR part 585 (USDOI, BOEM, 2012). The guidelines specify that BOEM 

recommends avoidance as a primary mitigation strategy. Avoidance strategies seek to reduce the 

likelihood of harm or damage to objects of historical or archaeological significance. The applicant 

has the option to demonstrate through additional investigations that an archaeological resource does 
Gulf of Mexico G&G Activities Programmatic EIS B-33

not exist or would not be adversely affected by the seafloor-disturbing activities. If an applicant 

discovers a potential archaeological resource such as the presence of a shipwreck (e.g., a sonar 

image or visual confirmation of an iron, steel, or wooden hull, wooden timbers, anchors, 

concentrations of historic objects, and piles of ballast rock), prehistoric artifacts, and/or relict 

landforms within the project area while conducting activities, the applicant is to

• immediately halt seafloor-disturbing activities within the area of discovery; 

• notify the appropriate BOEM Office of Offshore Alternative Energy Programs 

Environmental Branch Chief within 72 hours of the discovery; and

• keep the location of the discovery confidential and take no action that may 

adversely affect the archaeological resource until BOEM has made an evaluation 

and instructs the applicant on how to proceed.

BOEM may require the applicant to conduct additional investigations to determine if the 

resource is eligible for listing in the National Register of Historic Places.

In addition, BOEM has published guidelines for providing benthic habitat, bird, marine 

mammal, and sea turtle survey information for renewable energy projects on the Atlantic OCS that 

could be applied to the GOM (USDOI, BOEM, 2013). These guidelines provide recommendations 

for complying with information requirements of BOEM’s renewable energy regulations outlined within 

30 CFR part 585 subpart F. A Final Programmatic EIS for the OCS renewable energy program was 

released in 2007 (USDOI, MMS, 2007).

2.1.3 Endangered Species Act

The ESA established protection over and conservation of threatened and endangered 

species and the ecosystems upon which they depend. An endangered species is a species in 

danger of extinction throughout all or a significant portion of its range. A threatened species is one 

that is likely to become endangered within the near future throughout all or in a significant portion of 

its range. The U.S. Fish and Wildlife Service (FWS) and NMFS jointly administer the ESA and are 

responsible for the listing of species (designating a species as either threatened or endangered) and 

designating geographic areas as critical habitat for threatened and endangered species.

The ESA generally prohibits the “take” of an ESA-listed species unless an exception or 

exemption applies. The term “take,” as defined in Section 3 of the ESA, means to “harass, harm, 

pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such 

conduct.” Section 7(a)(2) requires each Federal agency to ensure that any action it authorizes, 

funds, or carries out is not likely to jeopardize the continued existence of any endangered or 

threatened species or result in the destruction or adverse modification of critical habitat of such 

species. When a Federal agency’s action may affect a listed species, that agency is required to 

consult with NMFS and/or the FWS under procedures set out in 50 CFR part 402. The FWS and 

NMFS can be action agencies under Section 7 as well. 
B-34 Protective Measures and Mitigation and Regulatory Requirements

Under Section 7, to initiate consultation, BOEM as the action agency would submit a 

consultation package, usually referred to as a Biological Assessment, to the appropriate service 

agency (NMFS and/or FWS) for proposed actions that may affect listed species or critical habitat. 

The relevant service reviews the Biological Assessment and provides BOEM a determination 

regarding the nature of any effects on each listed species or critical habitat and whether a formal or 

informal consultation is required. For each species likely to be adversely affected, formal 

consultation is required, ending with NMFS and/or FWS issuing a Biological Opinion. If the 

Biological Opinion concludes jeopardy is not likely, a Incidental Take Statement (ITS) will be issued 

containing the reasonable and prudent measures necessary or appropriate to minimize the impact of 

the taking, measures to comply with Section 101(a)(5) of the MMPA, and the terms and conditions to 

implement those measures. Taking in compliance with the ITS terms and conditions is exempt from 

the ESA’s takings prohibitions.

Informal consultation is sufficient for species the action agency determines are not likely to 

be adversely affected if NMFS or FWS concurs with the action agency’s findings, including any 

additional measures mutually agreed upon as necessary and sufficient to avoid adverse impacts to 

listed species and/or designated critical habitat.

2.1.4 Marine Mammal Protection Act

The MMPA established, with certain exceptions, a moratorium on the “taking” of marine 

mammals in waters or on lands under U.S. jurisdiction, and on the taking of marine mammals on the 

high seas by vessels or persons under U.S. jurisdiction. The term “take,” as defined in the MMPA

(16 U.S.C. § 1362 (13)), means “to harass, hunt, capture, or kill, or attempt to harass, hunt, capture, 

or kill any marine mammal.” “Harassment” was further defined in the 1994 amendments to the 

MMPA, which provided two levels of harassment relevant here: Level A (injury) and Level B 

(behavioral disturbance). Among the available exceptions to the take moratorium, the MMPA directs 

the Secretary of Commerce to allow, upon request, the incidental, but not intentional, taking of small 

numbers of marine mammals by U.S. citizens who engage in a specified activity (other than 

commercial fishing) within a specified geographical region if NMFS finds that the taking will have a 

negligible impact on the species or stock(s) and will not have an immitigable adverse impact on the 

availability of the species or stock(s) for taking for subsistence uses (where relevant). The 

authorization must set forth the permissible methods of taking; other means of effecting the least 

practicable adverse impact on the species or stock and its habitat; and requirements pertaining to 

the mitigation, monitoring, and reporting of such taking. Entities seeking to obtain authorization for 

the incidental take of marine mammals under NMFS jurisdiction must submit such a request (in the 

form of an application). The NMFS issued regulations to implement provisions of the MMPA 

(50 CFR 216 subpart I) and produced Office of Management and Budget (OMB)-approved 

application instructions (OMB Number 0648-0151) that prescribe the procedures necessary to apply 

for authorizations.

BOEM has determined that an ITA is warranted for G&G activities involving acoustic sources 

that could harass marine mammals. Therefore, this Programmatic EIS will support a petition for 
Gulf of Mexico G&G Activities Programmatic EIS B-35

incidental take regulations under the MMPA. The associated rulemaking would cover G&G 

activities, generally, within the three GOM planning areas. Industry would then be allowed to apply 

for individual ITAs under the resulting final regulations, if issued. Since the issuance of an ITA would 

allow for the taking of marine mammals, consistent with the provisions under the MMPA and 

incidental to the G&G activities, NOAA considers this issuance to be a major Federal action subject 

to NEPA. Therefore, NOAA’s National Marine Fisheries Service intends to adopt this Programmatic 

EIS as the NEPA documentation associated with authorizing incidental take of marine mammals. In 

addition, NMFS and ONMS may rely on the analysis within this Programmatic EIS to support 

consultation efforts under the ESA, MSFCMA, and NMSA. Additionally, NMFS intends to use this 

Programmatic EIS to support the issuance of proposed and final rules, respectively. While this

Programmatic EIS provides information about the possible locations relevant to requesting an ITA, 

including potential takes, the specific location and G&G activity details will not be known until BOEM 

receives an application. BOEM and BSEE’s approval for G&G activities will be conditional on the 

operator obtaining the necessary ITA from NMFS prior to commencing G&G activities.

2.1.5 Coastal Zone Management Act

The Coastal Zone Management Act (CZMA) of 1972 (16 U.S.C. §§ 1451 et seq.) was 

enacted to develop a national coastal management program that comprehensively manages and 

balances competing uses of and impacts to any coastal use or resource. The national coastal 

management program is implemented by individual State coastal management programs in 

partnership with the Federal Government. The CZMA’s Federal consistency regulations require that 

Federal activities (e.g., OCS lease sales) be consistent to the extent practicable with the enforceable 

policies of a State’s coastal management program. The Federal consistency regulations also 

require that other federally approved activities (e.g., activities requiring Federal permits such as 

activities described in OCS plans) be fully consistent with the enforceable policies of a State’s 

federally approved coastal management program. The CZMA is administered by the Office of 

Ocean and Coastal Resource Management within the National Ocean Service (NOS). The NOS’s 

implementing regulations are found at 15 CFR part 930, with the latest revision published in the 

Federal Register (2006). 

The overall program objectives of the CZMA are to “preserve, protect, develop, and where 

possible, to restore or enhance the resources of the nation’s coastal zone.” Each of the 34 coastal 

states (Alaska voluntarily withdrew from the National Coastal Zone Management Program in 2011) 

have programs to address the balance in competing land and water issues in the coastal zone. A 

State’s jurisdictional purview typically extends 3 nmi (3.5 mi; 5.6 km) offshore of the coast and 

coastal islands (Texas, the Gulf Coast of Florida, and Louisiana are exceptions). Texas and the Gulf 

Coast of Florida are extended 9 nmi (10.4 mi; 16.7 km) seaward, and Louisiana is extended 

3 imperial nmi (2.6 nmi; 4.8 km). In order to receive a permit from BOEM, an applicant’s proposed 

survey must be fully consistent with the enforceable policies of the State’s coastal management 

program by the affected State coastal zone management (CZM) agencies.
B-36 Protective Measures and Mitigation and Regulatory Requirements

During the review of the survey application under the proposed action, BOEM is to 

coordinate with the five Gulf Coast States through the CZMA, which helps the States develop 

coastal management programs to manage and balance competing uses of the coastal zone. The 

CZMA and implementing regulations require agency actions that are reasonably foreseeable to 

affect any land or water use, or natural resource of the coastal zone, to be consistent with 

enforceable policies of the five States’ coastal management program. Accordingly, BOEM is to 

provide the five Gulf Coast States with information on lease sales, as well as exploration and 

development plans for review during a designated period to conduct a consistency review to 

determine if the proposed activities are consistent with the States’ coastal management policies. If a 

coastal State determines that a proposed action by BOEM is not consistent with the State’s 

approved CZM program, it can pursue one of several administrative remedies.

2.1.6 Magnuson-Stevens Fishery Conservation and Management Act

The MSFCMA (P.L. 94-265) was enacted to address impacts to fisheries on the U.S. 

continental shelf. It established U.S. fishery management over fishes within the fishery conservation 

zone from the seaward boundary of the coastal states out to 200 nmi (230 mi; 370 km) (i.e., 

boundary of the U.S. Exclusive Economic Zone). The MSFCMA also established regulations for 

foreign fishing within the fishery conservation zone and issued national standards for fishery 

conservation and management to be applied by eight regional fishery management councils. Each 

council is responsible for developing Fishery Management Plans for domestic fisheries within its 

geographic jurisdiction. In 1996, Congress enacted amendments to the MSFCMA, known as the 

Sustainable Fisheries Act (P.L. 104-297), to address substantially reduced fish stocks resulting from 

direct and indirect habitat loss.

The Sustainable Fisheries Act requires BOEM and other agencies to consult with NMFS 

concerning actions that may adversely impact EFH. The EFH is defined as the waters and substrate 

necessary to fishes or invertebrates for spawning, breeding, feeding, or growth to maturity. Areas 

designated as EFH contain habitat essential to the long-term survival and health of U.S. fisheries. 

EFH for managed fisheries is described in the Fishery Management Plans. 

Federal agencies that authorize, fund, or undertake actions that might adversely affect EFH 

must consult with the Secretary of Commerce, through NMFS, regarding potential effects to EFH. 

To streamline the process, NMFS combines EFH consultations with existing environmental reviews 

required by other laws such as NEPA, and as a result, most consultations are completed within the 

time frames for review of other documents. BOEM requested consultation under the MSFCMA in 

conjunction with this Programmatic EIS. This Programmatic EIS provides information that will be 

relevant and applicable to support future consultations on EFH for site-specific G&G actions.

2.1.7 Clean Air Act

The OCSLA (43 U.S.C. § 1334(a)(8)) requires the Secretary of the Interior to promulgate and 

administer regulations that comply with the National Ambient Air Quality Standards pursuant to the 

Clean Air Act (CAA) (42 U.S.C. §§ 7401 et seq.) and to the extent that authorized activities 
Gulf of Mexico G&G Activities Programmatic EIS B-37

significantly affect the air quality of any state. Under provisions of the CAA, as amended, the 

USEPA Administrator, in consultation with the Secretary of the Interior and the Commandant of the 

USCG, established requirements to control air pollution in OCS areas of the Arctic, Atlantic, Pacific, 

and parts of the GOM.

The OCS sources within 25 nmi (29 mi; 46.3 km) of the States’ seaward boundaries are 

subject to the same Federal and State requirements as sources located onshore. OCS sources 

beyond 25 nmi (29 mi; 46.3 km) of the States’ boundaries are subject to Federal requirements for 

Prevention of Significant Deterioration promulgated pursuant to Part C of Title 1 of the CAA, as 

amended. The CAA, as amended, also established procedures to allow the USEPA Administrator to 

exempt any OCS source from a control technology requirement if it is technically infeasible or poses 

an unreasonable threat to health, safety, security, and the environment.

BOEM’s air quality regulations (30 CFR part 250 subpart C) assess and control OCS 

emissions that may impact air quality onshore. BOEM applies defined criteria to determine which 

OCS plans require an air quality review, and performs an impact-based analysis on the selected 

plans to determine whether the emission source could cause a significant onshore impact. If an 

emission source is determined to be significant and therefore requires air quality modeling, the 

USEPA’s preferred model (the Steady-State Gaussian, Offshore and Coastal Dispersion model) 

should be used.

Because the review under this document is programmatic in nature and does not address 

project-specific information regarding air quality issues, it will not result in a permit application under 

the CAA. Future site-specific proposals will be reviewed by BOEM to ensure CAA standards or 

permit requirements are met and that agreed-upon measures will avoid, minimize, or mitigate 

potential adverse effects.

2.1.8 Clean Water Act

The Clean Water Act (CWA) (33 U.S.C. §§ 1251 et seq.) established the basic structure for 

regulating discharges of pollutants into U.S. waters and regulating quality standards for surface 

waters. The basis of the CWA, enacted in 1948, was the Federal Water Pollution Control Act. 

When the Act was significantly reorganized and expanded with amendments in 1972, the common 

name became the Clean Water Act. Under the CWA, it is unlawful for any person to discharge any 

pollutant from a point source into navigable waters without a National Pollutant Discharge 

Elimination System (NPDES) permit. All waste streams generated from offshore oil and gas 

activities are regulated by the USEPA, primarily by general permits. The USEPA may not issue a 

permit for a discharge into ocean waters unless the discharge complies with the guidelines 

established under Section 403(c) of the CWA. These guidelines are intended to prevent degradation 

of the marine environment and require an assessment of the effect(s) of the proposed discharges on 

sensitive biological communities and aesthetic, recreational, and economic values.
B-38 Protective Measures and Mitigation and Regulatory Requirements

Other sections of the CWA also apply to offshore activities. Section 404 of the CWA requires 

a USACE permit for the discharge or deposition of dredged or fill material in all U.S. waters, 

including ocean areas and estuaries. Approval by the USACE, with consultation from other Federal 

and State agencies, is required for installing and maintaining pipelines and OCS seafloor structures 

in coastal areas. Section 303 of the CWA provides for the establishment of water quality standards 

that identify a designated use for waters (e.g., fishing and swimming). States (excluding Texas, the 

Gulf Coast of Florida, and Louisiana) have adopted water quality standards for ocean waters within 

their jurisdiction (waters of the territorial sea extending out to 3 nmi [3.5 mi; 5.6 km]). Texas and the 

Gulf Coast of Florida are extended 9 nmi (10.4 mi; 16.7 km) seaward, and Louisiana is extended 

3 imperial nmi (2.6 nmi; 4.8 km). Operators would be required to obtain an NPDES permit from the 

USEPA for any effluent discharges (including drilling fluids and cuttings) from a Continental Offshore 

Stratigraphic Test (COST) or shallow test well.

The USACE’s Nationwide Permit (NWP) Program, also called a general permit (USACE, 

2012) was developed to streamline the evaluation and approval process for certain types of activities 

that have minimal impacts to the aquatic environment. Any applicant that intends to use an NWP 

must ensure that their proposed activity meets the terms, conditions, and regional conditions of the 

NWP as well as any additional CZM program or Section 401 water quality requirements. Most G&G 

survey activities qualify for NWP 5 or NWP 6. The NWP 5 covers the placement of scientific 

measurement devices such as staff gauges, tide gauges, water recording devices, water quality 

testing and improvement devices, and similar structures applicable to certain G&G activities such as 

the temporary installation of meteorological buoys or other data collection devices. The NWP 6 

addresses survey activities such as core sampling, seismic exploratory operations, plugging of 

seismic shot holes and other exploratory-type bore holes, exploratory trenching, soil surveys, 

sampling, and historic resources surveys. Drilling and discharge of excavated material from test 

wells for oil and gas exploration are not authorized by NWP 6 and would require a 

Section 404/Section 10 permit, also called a standard permit.

Because the review under this document is programmatic in nature and does not address 

project-specific information regarding water quality issues, it will not result in a permit application 

under the CWA. Future, site-specific proposals will be reviewed by BOEM to ensure CWA 

standards or permit requirements are met and that agreed-upon measures will avoid, minimize, or 

mitigate potential adverse effects. The G&G surveys in State waters fall under the jurisdiction of the 

USACE and would not be subject to BOEM review.

2.1.9 Rivers and Harbors Act

The Rivers and Harbors Act (33 U.S.C. §§ 401, 403, and 407), enacted in 1899, was the first 

Federal water pollution act in the U.S. It focuses on protecting navigation and waters from pollution 

and acted as a precursor to the CWA of 1972. Section 10 (33 U.S.C. § 403) prohibits the 

unauthorized obstruction or alteration of any navigable water of the U.S. (i.e., construction of various 

structures that hinder navigable capacity of any waters) without the approval of Congress. While the 

initial purpose of the Rivers and Harbors Act was to prevent obstructions to navigation, a 
Gulf of Mexico G&G Activities Programmatic EIS B-39

1959 Supreme Court decision interpreted obstruction to navigation to include water pollution. The 

Supreme Court found anything that tends to destroy the navigable capacity of a navigable waterway 

is prohibited by the Rivers and Harbors Act. 

Section 10 is applicable for structures, installations, and other devices on the OCS seafloor. 

Section 10 is not applicable to most actions undertaken for exploration on the OCS, except for 

drilling and discharge of excavated material from test wells as they fall under NWP 6. An NWP 5 for 

“Scientific Measurement Devices” and an NWP 6 for “Survey Activities” are both appropriate for 

Section 10 actions. Because the review under this document is programmatic in nature and does 

not address project-specific information regarding impacts to navigable waters, it will not result in a 

permit application under the Rivers and Harbors Act. The USACE is the only agency that has the 

authority to make a decision to issue a Section 10 permit, based on an applicant’s submission of a 

USACE permit application and the USACE’s decision that the proposed activity is not contrary to the 

public interest.

2.1.10 National Historic Preservation Act

The National Historic Preservation Act (NHPA) of 1966, as amended (54 U.S.C. §§ 300101 

et seq.), established a program for the preservation of historic properties. Section 106 of the NHPA 

(36 CFR part 800), “Protection of Historic Properties,” as amended through 2004, requires Federal 

agencies that have direct or indirect jurisdiction over a proposed Federal, federally assisted, or 

federally licensed undertaking to take into account the effect of the undertaking on any district, site, 

building, structure, or object included in or eligible for inclusion in the National Register of Historic 

Places prior to approval of the expenditure of funds or the issuance of a license. The Advisory 

Council on Historic Preservation (ACHP), which administers Section 106 (54 U.S.C. § 306108), has 

issued regulations (36 CFR part 800) defining how Federal agencies are to meet the statutory 

responsibilities. The head of a Federal agency will afford the ACHP a reasonable opportunity to 

review and comment on the action.

An action has an effect on a historic property when that action alters the characteristics of 

the property that led to its inclusion in the National Register of Historic Places. The effects can 

include physical disturbance, noise, or visual effects. If an adverse effect on historic properties is 

found, BOEM would notify the ACHP, consult with the State Historic Preservation Office, and 

encourage the applicant to avoid, minimize, or mitigate the adverse effects. Ground-disturbing 

activities associated with construction, as well as visual effects of OCS energy infrastructure (e.g., 

wind turbine generators) are subject to Section 106 review.

Historic properties (i.e., archaeological resources) on the OCS include historic shipwrecks, 

sunken aircraft, lighthouses, and prehistoric archaeological sites that have become inundated as a 

result of the 120-m (394-ft) rise in global sea level since the height of the last Ice Age (approximately 

19,000 years ago). The OCS is not federally owned land, and the Federal Government has not 

claimed direct ownership of historic properties on the OCS; therefore, under Section 106 of the 

NHPA, the Bureau of Ocean Energy Management only has the authority to ensure that their funded 
B-40 Protective Measures and Mitigation and Regulatory Requirements

and permitted actions do not adversely affect significant historic properties. Beyond avoidance of 

adverse impacts, BOEM does not have the legal authority to manage historic properties on the OCS.

For the activities within the proposed action, BOEM will make a determination as to whether 

the actions could affect historic properties, including those already in the National Register of 

Historic Places and those that meet the criteria for listing. If it is determined the action could affect 

such properties, BOEM will identify the appropriate State/Tribal Historic Preservation Officer to 

consult with during the process. Consultation is expected to result in an Memorandum of 

Agreement, outlining agreed-upon measures that BOEM will take to avoid, minimize, or mitigate 

adverse effects.

2.1.11 Marine Protection, Research, and Sanctuaries Act

The Marine Protection, Research, and Sanctuaries Act (MPRSA) (33 U.S.C. §§ 1401 

et seq.), enacted in 1972 and also referred to as the Ocean Dumping Act, generally prohibits 

(1) transportation of material from the U.S. for the purpose of ocean dumping, (2) transportation of 

material from anywhere for the purpose of ocean dumping by U.S. agencies or U.S.-flagged vessels, 

and (3) dumping of material transported from outside the U.S. into the U.S. territorial sea. A permit 

is required to deviate from these prohibitions.

Under the MPRSA, the standard for permit issuance is whether the dumping will 

“unreasonably degrade or endanger” human health, welfare, or the marine environment. The 

USEPA is charged with developing ocean dumping criteria to be used in evaluating permit 

applications. The MPRSA contains provisions that address marine sanctuaries, which are 

administered by NOAA.

2.1.12 National Marine Sanctuaries Act

The NMSA authorizes the Secretary of Commerce to designate and manage areas of the 

marine environment with special national significance. The ONMS, administered by NOAA, has the 

authority to permit or authorize activities that would occur within or near an NMS. The ONMS 

manages the uses of the National Marine Sanctuary System through issuing programmatic and 

site-specific regulations; issuing permits or authorizations for activities that are otherwise prohibited; 

enforcing regulations and permits; consulting with Federal agencies and recommending alternatives 

to activities that are likely to injure sanctuary resources; and conducting research, monitoring, 

education, and outreach for all NMSs. The NMSA and ONMS regulations provide four forms of 

approval to allow an entity to conduct an activity otherwise prohibited by ONMS regulations: 

(1) General permits may be issued to allow activities that are otherwise prohibited 

by sanctuary regulations (15 CFR part 922). Prohibitions are sanctuary-specific 

but commonly include disturbance of submerged lands and discharges within or 

into the sanctuary. General permits are reviewed against specific permit 

categories and review criteria established in regulation.
Gulf of Mexico G&G Activities Programmatic EIS B-41

(2) Authorizations to implement permits granted by other Federal, State, or local 

agencies allow otherwise prohibited activities and may include additional terms 

and conditions, as appropriate.

(3) Special use permits may be issued to establish conditions of access to a 

sanctuary resource, or promote the public use and understanding of a 

sanctuary resource. The list of categories of activities applicable to special use 

permits are published in the Federal Register. Special use permits are granted 

only when the activity is compatible with the purpose for which the sanctuary 

was designated and sanctuary resources will not be injured. The ONMS may 

assess fees associated with special use permits for administrative costs, 

implementation and monitoring costs, and the fair market value of the use of the 

NMS. 

(4) Certifications may be issued to allow otherwise prohibited activities to continue 

following the designation of a new sanctuary or expansion of an existing 

sanctuary. Preexisting Federal, State, or local permits may not be terminated 

pursuant to the NMSA. However, ONMS may regulate the exercise of such 

permits consistent with the purpose for which the sanctuary was designated. 

The permit holder seeking a certification from ONMS must comply with the 

procedures and criteria promulgated at the time of sanctuary designation or 

expansion.

Most NMS regulations explicitly prohibit harassment of marine mammals, sea turtles, and 

birds by any means unless authorized by the MMPA, ESA, or Migratory Bird Treaty Act, though 

additional restrictions vary across sanctuaries. Pursuant to a Presidential directive, NMSs

designated as of July 14, 2008, are withdrawn from new oil/gas leases. The Flower Garden Banks 

NMS allows exploration for developing and producing oil and gas outside of BOEM’s “No Activity 

Zones.” The Florida Keys NMS regulations prohibit the exploration for hydrocarbons within the 

sanctuary. In addition, if G&G activities include the potential for discharge or seafloor disturbance 

within the sites, permits from the NMS may be required.

Section 304(d) of the NMSA requires interagency consultation on any Federal action “likely 

to destroy, cause the loss of, or injure a sanctuary resource.” “Actions” include direct Federal 

actions and activities authorized by Federal licenses, leases, or permits. The action can occur 

internal or external to the boundaries of an NMS. The purpose of Section 304(d) consultation is to 

provide better protection sanctuary resources by requiring Federal agencies to consider alternatives 

to proposed actions that will protect sanctuary resources and avoid injury. The ONMS works 

cooperatively with Federal agencies in proactively identifying actions that may require NMSA 

consultation and completing sanctuary consultation at the earliest practicable time. BOEM will 

consult with ONMS under Section 304(d) when they receive an application that indicates a G&G 

activity may occur within or near the Flower Garden Banks NMS or the Florida Keys NMS. In 

addition, NMFS consults with the ONMS when an authorization would include takes of marine 
B-42 Protective Measures and Mitigation and Regulatory Requirements

mammals within the boundaries of an NMS. Upon receipt of ITA applications, NMFS will determine 

its need to consult with ONMS. Although the determination and responsibility to consult under 

Section 304(d) resides with the Federal agencies (i.e., NOAA and BOEM), applicants may need to 

acquire permits directly from ONMS for activities that are prohibited within the sanctuary (refer to the

earlier description). Additional information on sanctuary consultation can be obtained at 

http://sanctuaries.noaa.gov/management/consultations/welcome.html. 

2.1.13 Migratory Bird Treaty Act

The Migratory Bird Treaty Act (MBTA) of 1918 (16 U.S.C. §§ 703-712) is the primary 

legislation in the U.S. for the conservation of migratory birds. It implements the U.S.’s commitment 

to four bilateral treaties, or conventions, for the protection of a shared migratory bird resource. The 

MBTA prohibits the taking, killing, or possessing of migratory birds unless permitted by regulation. 

The bird species protected by the MBTA appear in the Federal Register (2010a). Executive 

Order 13186 (“Responsibilities of Federal Agencies to Protect Migratory Birds”), signed on 

January 10, 2001 (Federal Register, 2001), requires that Federal agencies taking actions likely to 

negatively affect migratory bird populations enter into Memorandums of Understanding (MOUs) with 

the FWS. 

On June 4, 2009, BOEM entered into an MOU with the FWS to comply with Executive 

Order 13186 (USDOI, MMS, 2009). The MOU is meant to strengthen collaboration between BOEM, 

BSEE, and FWS. Included in the MOU is direction to expand coverage in NEPA environmental 

reviews of the effects of agency actions on migratory birds, with emphasis on species of concern in 

furtherance of conservation of migratory bird populations. The original MOU was signed by MMS 

and FWS. BOEM and BSEE are currently in the process of extending the MOU with FWS and 

changing the responsible parties from MMS and FWS to BOEM, BSEE, and FWS to reflect the 

reorganization of duties. Future site-specific proposals will be reviewed by BOEM and BSEE to 

ensure MBTA standards are addressed in the manner outlined in the MOU.

2.1.14 Fish and Wildlife Coordination Act

The Fish and Wildlife Coordination Act (FWCA) (16 U.S.C. §§ 661-666c), enacted March 10, 

1934, is intended to protect fish and wildlife when Federal actions result in the control or modification 

of a natural stream or body of water. The FWCA provides the basic authority for the involvement of 

FWS in evaluating impacts to fish and wildlife from proposed water resource development projects. 

The FWCA requires that all Federal agencies consult with FWS, NMFS, and State wildlife agencies 

for activities that affect, control, or modify waters of any stream or bodies of water.

2.1.15 CFR Title 30: Mineral Resources

Pre-lease (and some post-lease) G&G exploratory (prospecting) operations for oil, gas, and 

sulphur resources, or for scientific research on unleased OCS lands and across leases owned by a 

third party are regulated by 30 CFR part 551. All pre-lease G&G surveys require a permit under 

30 CFR part 551. Each permit application is subject to a site-specific NEPA evaluation, which 
Gulf of Mexico G&G Activities Programmatic EIS B-43

typically is an EA (Table 1.1-2 of this Programmatic EIS). In the AOI, this Programmatic EIS 

provides that evaluation, from which site-specific evaluations may be tiered under the NEPA 

regulations (40 CFR § 1502.20).

On-lease oil and gas activity on the OCS is regulated by 30 CFR part 550 after a lease is 

acquired. Post-lease activities and G&G activities that are required to support them are governed by 

a series of OCS plans (Table 1.1-2 of this Programmatic EIS). An exploration plan guides any 

exploration activities on a lease or unit, and a DOCD (submitted for the USEPA) or Development 

and Production Plan (DPP) (submitted for the CPA and EPA) guides any development and 

production activities on a lease or unit.

A G&G permit must be obtained from BOEM prior to conducting off-lease G&G activities on 

unleased OCS lands or on lands under lease to a third party (30 CFR §§ 551.4(a) and (b)).

Ancillary activities are post-lease operations by lease owners in furtherance of developing oil 

and gas resources. Ancillary G&G activities are defined in 30 CFR §§ 250.105 and 550.105 with 

regulations outlined in 30 CFR §§ 550.207-550.210 (Table 1.1-1 of this Programmatic EIS). BOEM 

issued NTL 2009-G34, “Ancillary Activities,” to provide guidance and clarification on conducting 

ancillary activities in BOEM’s Gulf of Mexico OCS Region. Guidance for each type of ancillary 

activity, the type and level of BOEM review, and follow-up post-survey report requirements are 

provided in NTL 2009-G34. The NTL expired on November 30, 2014, and renewal language has not 

been issued; however, NTL 2015-N02 was issued in February 2015 and eliminates expiration dates 

on certain lessees and operators pending review and reissuance.

Regulations governing non-energy (marine) mineral prospecting, leasing, and production are 

in 30 CFR part 580 (prospecting), part 581 (leasing), and part 582 (production). In 1994, 

P.L. 103-426 was enacted, allowing BOEM to negotiate, on a noncompetitive basis, the rights to 

OCS sand, gravel, or shell resources for shore protection, beach or wetlands restoration projects, or 

for use in construction projects funded in whole or part by or authorized by the Federal Government. 

The G&G activities associated with these noncompetitive leases for public works are issued 

authorizations pursuant to Section 11 of the OCSLA. For all other uses, such as private use for 

commercial construction material, a competitive bidding process is required for issuing leases under 

Section 8(k) of the OCSLA.

2.1.15.1 Notice to Lessees and Operators

Guidance for each type of ancillary activity, the type and level of BOEM review, follow-up 

actions, and post-survey report requirements are provided in NTL 2009-G34. The NTL also 

specifies that operators must notify BOEM in writing at least 30 calendar days (30 CFR § 

250.208(a)) before conducting any of the following types of ancillary activities:
B-44 Protective Measures and Mitigation and Regulatory Requirements

• a G&G exploration or development activity involving the use of an airgun or 

airgun arrays in water depths ≥200 m (656 ft) or in any water depth within the 

EPA; 

• a G&G exploration or development activity involving the use of explosives as an 

energy source, independent of water depth; and

• a G&G exploration or development activity including OBC, OBN, and time-lapse 

(4D) surveys, independent of water depth.

Additionally, NTL 2009-G34 specifies that operators must notify BOEM in writing at least 

15 calendar days (30 CFR § 250.208(b)(1)) before conducting the following types of ancillary 

activities:

• any other ancillary activity involving seafloor disturbance, independent of water 

depth, including OBC, OBN, and time-lapse (4D) surveys; and

• any other ancillary activity involving piston-/gravity-coring or the recovery of 

sediment specimens by grab sampling or similar technique and/or any dredging 

or other ancillary activity that disturbs the seafloor (including deployment and 

retrieval of OBCs, anchors, or other equipment).

Ancillary activities are subject to conditional NEPA reviews (Table 1.1-2 of this Programmatic 

EIS) depending on what activity is being proposed. Generally, any G&G survey using an airgun or 

that involves explosives or seafloor-disturbing activity is evaluated with an EA. If BOEM determines 

that the type of proposed activity necessitates revising an existing OCS plan, a NEPA review is 

triggered (usually an EA). In addition to the NEPA review, the operator must have an approved 

exploration plan, DOCD, or DPP, each of which would have been subject to a NEPA review as part 

of initial plan approval.

2.1.16 Executive Order 12114 – Environmental Effects Abroad of Major Federal 

Actions

Issued on January 4, 1979, by President Carter, Executive Order 12114 directs Federal 

agencies to provide for informed decisionmaking for major Federal actions with effects that occur 

outside the 50 states, territories, and possessions of the U.S., including marine waters seaward of 

U.S. territorial seas, the global commons, the environment of a nonparticipating foreign nation, or 

effects to protected global resources. Global commons are defined as “geographical areas that are 

outside of the jurisdiction of any nation, and include the oceans outside territorial limits and 

Antarctica. Global commons do not include contiguous zones and fisheries zones of foreign nations” 

(32 CFR § 187.3).

An Overseas EIS is required when an action could significantly harm the environment of the 

global commons. The procedural requirements under Executive Order 12114 largely mirror those of 

NEPA, except Executive Order 12114 does not require scoping. For this action, the EIS and 
Gulf of Mexico G&G Activities Programmatic EIS B-45

Overseas EIS have been combined into one document, as permitted under NEPA and Executive 

Order 12114, in order to reduce duplication. The AOI for this proposed action is within the Exclusive 

Economic Zone; specifically, within the WPA, CPA, and EPA as currently defined.

2.1.17 Executive Order 12898 – Federal Actions to Address Environmental 

Justice in Minority Populations and Low-Income Populations

Signed on February 11, 1994, by President Clinton, Executive Order 12898 requires that 

each Federal agency, to the extent practicable and permitted by law, make achieving environmental 

justice part of its mission by identifying and addressing, as appropriate, disproportionately high and 

adverse human health or environmental effects of its programs, policies, and activities on minority 

and low-income populations. The Executive Order required that, within 1 year, each Federal agency 

develop an environmental justice strategy identifying and addressing disproportionately high and 

adverse human health or environmental effects of its programs, policies, and activities on minority 

and low-income populations. The CEQ has oversight of the Federal Government’s compliance with 

Executive Order 12898. The CEQ (1997) guidance for implementation of Executive Order 12898 in 

the context of NEPA identifies a minority population as an affected area where >50 percent of the 

population belongs to a minority group or where the percentage presence of minority groups is 

meaningfully greater than in the general population.

Potential environmental justice communities have been identified in this Programmatic EIS 

(refer to Appendix E, Section 13.2). Future environmental reviews of site-specific projects would 

be expected to identify individual low-income communities (such as fishing communities) and assess 

any disproportionate human health and environmental effects that these communities could face.

2.1.18 Executive Order 12989 – Economy and Efficiency in Government 

Procurement through Compliance with Certain Immigration and 

Naturalization Act Provisions

Signed on February 13, 1996, by President Clinton, Executive Order 12989 was designed to 

promote economy and efficiency in government procurement (Federal Register, 1996). This 

Executive Order made it the policy of the executive branch that in procuring goods and services, to 

ensure the economical and efficient administration and completion of Federal Government contracts, 

contracting agencies should not contract with employers that have not complied with sections of the 

Immigration and Nationality Act (8 U.S.C. § 1324) prohibiting the unlawful employment of aliens. 

Since being enacted, this Executive Order has been amended by Executive Order 13286 on 

February 28, 2003, and by Executive Order 13465 on June 6, 2008.

2.1.19 Executive Order 13089 – Coral Reef Protection Act

Signed on June 11, 1998, by President Clinton, Executive Order 13098 preserved and 

protected the coral reef ecosystems of the U.S. This Executive Order acts in furtherance of the 

CWA, CZMA, MSFCMA, NEPA, and NMSA. All Federal agencies whose actions may affect U.S. 

coral reef ecosystems will (1) identify their actions that may affect U.S. coral reef ecosystems; 
B-46 Protective Measures and Mitigation and Regulatory Requirements

(2) utilize their programs and authorities to protect and enhance the conditions of such ecosystems; 

and (3) to the extent permitted by law, ensure that any actions they authorize, fund, or carry out will 

not degrade the conditions of such ecosystems (Federal Register, 1998). The Secretary of the 

Interior serves as a co-chair for the U.S. Coral Reef Task Force.

Because the review under this document is programmatic in nature and does not address 

project-specific information regarding impacts to coral reefs, it will not result in specific stipulations 

beyond those found in survey protocols (refer to Chapter 2 of this Programmatic EIS). BOEM will 

require site-specific information regarding sensitive benthic communities (including hard/live bottom 

areas, deepwater coral communities, and chemosynthetic communities) prior to approving any G&G 

activities involving seafloor-disturbing activities or placement of bottom-founded equipment or 

structures. 

2.1.20 Executive Order 13158 – Marine Protected Areas

Signed on May 26, 2000, by President Clinton, Executive Order 13158 strengthened and 

expanded the Nation’s system of Marine Protected Areas (MPAs) (Federal Register, 2000a). 

Specifically, consistent with domestic and international law, the Executive Order was to 

(1) strengthen the management, protection, and conservation of existing MPAs and establish new or 

expanded MPAs; (2) develop a scientifically based, comprehensive national system of MPAs 

representing diverse U.S. marine ecosystems as well as the Nation’s natural and cultural resources; 

and (3) avoid causing harm to MPAs through federally conducted, approved, or funded activities. 

The South Atlantic Fishery Management Council (2011) defines MPAs within its jurisdiction as a 

network of specific areas of marine environments reserved and managed for the primary purpose of 

aiding in the recovery of overfished stocks and to ensure the persistence of healthy fish stocks, 

fisheries, and associated habitats. Such areas may include naturally occurring or artificial seafloor 

and water column habitats, and may include prohibition of harvest on seasonal or permanent time 

periods to achieve desired fishery conservation and management goals.

Because the review under this document is programmatic in nature and does not address 

project-specific information regarding impacts to MPAs, it will not result in specific stipulations 

regarding MPAs beyond those found in survey protocols (refer to Chapter 2 of this Programmatic 

EIS). BOEM will require site-specific information regarding sensitive benthic communities that might 

be found in MPAs (including hard/live bottom areas, deepwater coral communities, and 

chemosynthetic communities) prior to approving any G&G activities involving seafloor-disturbing 

activities or placement of bottom-founded equipment or structures.

2.1.21 Executive Order 13175 – Consultation and Coordination with Federally 

Recognized Indian Tribes

Signed on November 6, 2000, by President Clinton, Executive Order 13175 established 

regular and meaningful consultation and collaboration with Tribal officials in the development of 

Federal policies that have Tribal implications to strengthen the U.S. government-to-government 

relationships with Indian Tribes and to reduce the imposition of unfunded mandates upon Indian 
Gulf of Mexico G&G Activities Programmatic EIS B-47

Tribes. The Executive Order directed Federal agencies to establish procedures to consult and 

collaborate with Tribal governments when new agency regulations would have Tribal implications. 

This Executive Order is a directive to all Federal agencies, but it only has persuasive authority for 

independent regulatory agencies (e.g., Federal Communications Commission and Securities and 

Exchange Commission) and is not meant to create a right, substantial or procedural, that is 

enforceable by law.

2.1.22 Executive Order 13547 – Stewardship of the Ocean, Our Coasts, and the 

Great Lakes

Signed on July 19, 2010, by President Obama, Executive Order 13547 established a national 

ocean policy and the National Ocean Council (Federal Register, 2010b). The Executive Order

established a national policy to ensure the protection, maintenance, and restoration of the health of 

ocean, coastal, and Great Lakes ecosystems and resources; to enhance the sustainability of ocean 

and coastal economies; to preserve maritime heritage; to support sustainable uses and access; to 

provide for adaptive management to enhance understanding of and capacity to respond to climate 

change and ocean acidification; and to coordinate with U.S. national security and foreign policy 

interests. Where BOEM’s actions affect the ocean, the Executive Order requires BOEM to take such 

action as necessary to implement this policy, the stewardship principles, national priority objectives 

adopted by the Executive Order, and guidance from the National Ocean Council.

Implementation of the guidelines presented in Executive Order 13547 is still in the planning 

stages at BOEM and will occur in a three-stage process that will culminate with a final Coastal 

Marine Spatial Planning process.

2.1.23 U.S./Mexico Transboundary Hydrocarbons Agreement and H.R. 1613 – 

Outer Continental Shelf Transboundary Hydrocarbon Agreements 

Authorization Act

The U.S./Mexico Transboundary Hydrocarbons Agreement, signed on February 20, 2012, 

and ratified by the Mexican Senate in April 2012, established a framework for the cooperative 

exploration and exploitation of hydrocarbon resources that cross the U.S./Mexico maritime boundary 

in the GOM (excluding areas under the jurisdiction of Texas). It allows leaseholders on the U.S. side 

of the boundary to cooperate with the Mexican national oil company, Pemex, in the joint exploration 

and exploitation of hydrocarbon resources. The Agreement also ends the moratorium on 

exploitation along the boundary in the Western Gap and provides U.S. leaseholders with legal 

certainty regarding the exploitation of transboundary reservoirs along the entire boundary so as to 

encourage investment.

House Resolution (H.R.) 1613, the “OCS Transboundary Hydrocarbon Agreements 

Authorization Act”, would approve the agreement between the U.S. and Mexico regarding the 

development of oil and gas natural resources on the OCS in the area of the GOM where the two 

countries share a border. The bill would amend the OCSLA to authorize the Secretary of the Interior 

to implement any agreement for the management of transboundary hydrocarbon reservoirs. On 
B-48 Protective Measures and Mitigation and Regulatory Requirements

June 27, 2013, H.R. 1613 passed in the House of Representatives, and it has moved to the Senate 

for consideration.

2.2 FEDERAL AGENCIES

2.2.1 Bureau of Ocean Energy Management

The OCSLA directs BOEM to ensure that G&G data are obtained in a technologically safe 

and environmentally sound manner. All G&G activities are subject to permits, notices, 

authorizations, or COAs depending on the specific Program Area and associated regulations and 

policies. BOEM oversees G&G data acquisition and permitting activities pursuant to 30 CFR parts 

550, 551, 580, and 585; Section 11, Subsections 8(k) and 8(p) of the OCSLA; and Section 388(a) of 

the EPAct of 2005. These regulations, in part, state that G&G activities cannot

• interfere with or endanger operations under any lease or right-of-way easement, 

right-of-use, scientific notice, or permit issued or maintained pursuant to OCSLA;

• cause harm or damage to life (including fish and other aquatic life), property, or 

the marine, coastal, or human environment;

• cause harm or damage to any mineral resource (in areas leased or not leased);

• cause pollution;

• create hazardous or unsafe conditions;

• unreasonably interfere with or harm other uses of the area; or

• disturb archeological resources.

The regulations under 30 CFR parts 550, 551, 580, and 585 governing G&G surveys are 

summarized in Table 1.1-1 of this Programmatic EIS.

2.2.2 Bureau of Safety and Environmental Enforcement

As part of a major reorganization of the USDOI’s offshore regulatory structure, BSEE was 

formally established on October 1, 2011. The BSEE uses the full range of authorities, policies, and 

tools to compel safety, emergency preparedness, environmental responsibility, and appropriate 

development and conservation of offshore oil and natural gas resources (refer to Chapter 1 of this

Programmatic EIS for additional information).

The newly created Environmental Compliance Division of BSEE is a first in the Federal 

offshore energy regulatory program. The Environmental Compliance Division will provide sustained 

regulatory oversight focused on compliance by operators with all applicable environmental 

regulations, as well as ensure operators keep promises they make at the time they obtain leases, 

submit plans, and apply for permits.
Gulf of Mexico G&G Activities Programmatic EIS B-49

The Chief of the Environmental Compliance Division establishes national strategic goals of 

the environmental compliance program to increase the accuracy and consistency of its 

environmental compliance activities per NEPA, the OCSLA, and other statutory requirements. The 

Enviromental Compliance Division establishes national data needs for the environmental compliance 

program, maintains and monitors national performance standards, and sets national policies 

regarding environmental compliance activities conducted by BSEE personnel. The Environmental 

Compliance Division is also responsible for monitoring execution and effectiveness of environmental 

compliance activity.

2.2.3 National Oceanic and Atmospheric Administration

The NOAA executes its mission and statutory mandates through the following offices: 

• National Environmental Satellite, Data, and Information Service; 

• National Marine Fisheries Service; 

• National Ocean Service; 

• National Weather Service; 

• Office of Marine & Aviation Operations; and

• Office of Oceanic and Atmospheric Research. 

These offices represent the operating branches of NOAA and are responsible for managing 

the delivery of products and services to meet the needs of the public, various Federal and State 

agencies, and other stakeholders. The ONMS (under NOS) and NMFS are the primary offices 

within NOAA that participated in the development of this Programmatic EIS because of their 

expertise and statutory responsibilities to protect, conserve, and recover marine mammals as well as

threatened and endangered species, and to conserve and manage fisheries and the NMSs. 

Subsequently, early participation of these NOAA offices during the preparation of this Programmatic 

EIS aided BOEM’s analysis of potential impacts to various protected resources within the GOM,

including EFH and the NMSs. 

Since the issuance of an ITA would allow for the taking of marine mammals, consistent with 

the provisions under the MMPA and incidental to the G&G activities, NOAA considers this issuance 

to be a major Federal action subject to NEPA. Therefore, NOAA’s National Marine Fisheries Service

intends to adopt this Programmatic EIS as the NEPA documentation associated with authorizing 

incidental take of marine mammals. In addition, NMFS and ONMS may rely on the analysis within 

this Programmatic EIS to support consultation efforts under the ESA, MSFCMA, and NMSA.
B-50 Protective Measures and Mitigation and Regulatory Requirements

3 STATE REGULATIONS AND AGENCIES

3.1 COASTAL ZONE MANAGEMENT ACT

The CZMA and its amendments were established to develop comprehensive programs to 

manage and balance competing uses of and impacts to coastal resources. The CZMA emphasizes 

the importance of State decisionmaking regarding the coastal zone to protect, develop, and where 

possible restore or enhance the resources of the Nation’s coastal zone for current and future 

generations. The CZMA also encourages and assists States in effectively exercising their 

responsibilities in the coastal zone through the development and implementation of management 

programs to wisely use the land and water resources of the coastal zone, giving full consideration to 

ecological, cultural, historic, and aesthetic values as well as the needs for compatible economic 

development. Each State’s Coastal Management Program (CMP), federally approved by NOAA, is 

a comprehensive statement setting forth objectives, enforceable policies, and standards for public 

and private use of land and water resources in the State’s coastal zone. The CMP provides for 

direct State land and water use planning and regulations. The CMP also includes a definition of 

what constitutes permissible land uses and water uses. Federal consistency is the CZMA 

requirement where Federal agency activities that have reasonably foreseeable effects on any land or 

water use or natural resource of the coastal zone must be consistent to the maximum extent 

practicable with the enforceable policies of a coastal State’s federally approved CMP. The latest 

Federal consistency regulations concerning State coastal zone management programs are found in 

the Federal Register (2000b, 2006).

Each Gulf Coast State’s official coastal boundary can be identified from NOAA’s website at 

https://coast.noaa.gov/czm/media/StateCZBoundaries.pdf. Once a State’s CMP is federally 

approved, Federal agencies must ensure that their actions are consistent, to the maximum extent 

practicable, with the enforceable polices of the approved program. Federal agencies provide 

feedback to the States through Section 312 evaluations conducted by NOAA.

To ensure conformance with State CMP policies and local land-use plans, BOEM prepares a 

Federal consistency determination for each proposed OCS lease sale. Through the designated 

State CZM agency, local land-use entities are provided numerous opportunities to comment on the 

OCS Program. Local land-use agencies also have the opportunity to comment directly to BOEM at 

any time, including during formal public comment periods related to the announcement of the 

Five-Year Program, Call for Information/Notice of Intent, EIS scoping, public hearings on the Draft 

EIS, and the Proposed Notice of Sale.

A State’s approved CMP may provide for the State’s review of OCS plans, permits, and 

license activities to determine whether they will be conducted in a manner consistent with the State’s 

CMP. This review authority is applicable to activities conducted in any area that has been leased 

under the OCSLA and that affect any land or water use or natural resource within the State’s coastal 

zone (16 U.S.C. § 1456(c)(3)(B)).
Gulf of Mexico G&G Activities Programmatic EIS B-51

The sections below provide an overview of the CMP within each Gulf Coast State bordering 

the AOI.

3.1.1 State of Florida Coastal Management Program

For purposes of the CZMA, the State of Florida’s coastal zone includes the area 

encompassed by the State’s 67 counties and its territorial seas. Lands owned by the Federal 

Government and the Seminole and Miccosukee Indian Tribes are not included in the State’s coastal 

zone; however, Federal activities in or outside the coastal zone, including those on Federal or Tribal 

lands, that affect any land, water, or natural resource of the State’s coastal zone are subject to 

review by Florida under the CZMA. The Florida Coastal Management Act, codified as Chapter 380, 

Part II, Florida Statutes, authorized the development of a coastal management program. In 1981, 

the Florida Coastal Management Program (FCMP) was approved by NOAA.

The policies identified by the State of Florida as being enforceable in the FCMP are the 

24 chapters that NOAA approved for incorporation in the State’s program. The 2015 Florida 

Statutes are the most recent version approved by NOAA.

A network of eight State agencies and five regional water management districts implement 

the FCMP’s 24 statutes. The water management districts are responsible for water quantity and 

quality throughout the State’s watersheds. The State agencies include the following: 

• the Department of Environmental Protection (DEP), the lead agency for the 

FCMP and the State’s chief environmental regulatory agency and steward of its 

natural resources; 

• the Department of Economic Opportunity, which administers State and Federal 

programs and initiatives to help visitors, citizens, businesses, and communities; 

• the Department of Health, which, among other responsibilities, regulates on-site 

sewage disposal; 

• the Department of State, Division of Historical Resources, which protects historic 

and archaeological resources; 

• the Fish and Wildlife Conservation Commission, which protects and regulates 

freshwater and saltwater fisheries, marine mammals, birds, and upland species, 

including protected species and the habitat used by these species; 

• the Department of Transportation, which is charged with the development, 

maintenance, and protection of the transportation system; 

• the Department of Agriculture and Consumer Services, which manages State 

forests and administers aquaculture and mosquito control programs; 

• and the Governor’s Office of Planning and Budget, which plays a role in the 

comprehensive planning process.
B-52 Protective Measures and Mitigation and Regulatory Requirements

Effective July 1, 2000, the Governor of Florida assigned the State’s responsibilities under the 

OCSLA to the Secretary of the Florida DEP. The DEP’s Office of Intergovernmental Programs 

coordinates the review of OCS plans with FCMP member agencies to ensure that the plan is 

consistent with applicable State enforceable policies and the Governor’s responsibilities under the 

OCSLA.

BOEM developed coordination procedures with the State for the submittal of offshore lease 

sale consistency determinations and plans of operation. In 2003, BOEM and the State revised CZM 

consistency information for OCS plans, permits, and licenses to conform with the revised CZM 

regulations that were effective January 8, 2001 (updated on January 5, 2006), and they have 

incorporated streamlining improvements into the latest NTLs (NTLs 2008-G04, 2009-G27, and 

2015-N01). Federal consistency for right-of-way pipelines is addressed in NTL 2007-G20.

The State of Florida requires an adequate description, objective, and schedule for all 

activities associated with a project; specific information on the natural resources potentially affected 

by the proposed activities; specific information on the onshore support base, support vessels, 

shallow hazards, oil-spill response, wastes and discharges, transportation activities, and air 

emissions; and a Federal consistency certification, assessment, and findings. As identified by the 

State of Florida, the State’s enforceable policies that must be addressed for OCS activities are found 

at http://www.boem.gov/Environmental-Stewardship/Environmental-Assessment/CZMA/CZMProgram-Policies-for-GOM-States-pdf.aspx. These requirements have been incorporated into the 

plans and regional oil-spill response NTLs. The State requirements for Federal consistency review 

are based on the requirements of State statutes, CZMA regulations at 15 CFR part 930, and the 

USDOI’s regulations at 30 CFR parts 250, 254, 256, and 550. BOEM is continuing a dialogue with 

the State of Florida on reasonably foreseeable coastal effects associated with OCS plans, pipelines, 

and other permits; the result of these discussions will be incorporated into future updates of BOEM’s 

permitting procedures and/or NTLs.

3.1.2 State of Alabama Coastal Management Program

The Alabama Coastal Area Act (ACAA) provides statutory authority to review all coastal 

resource uses and activities that have a direct and significant effect on the coastal area. The 

Alabama Department of Conservation and Natural Resources (ADCNR) Lands Division, Coastal 

Section Office, the lead coastal management agency, is responsible for the management of the 

State’s coastal resources through the Alabama Coastal Area Management Program (ACAMP). The 

ADCNR is responsible for the overall management of the program, including fiscal and grants 

management as well as public education and information. The ADCNR also provides planning and 

technical assistance to local governments and financial assistance to research facilities and units of 

local government when appropriate. The State Lands Division, Coastal Section, also has authority 

over submerged lands in regard to piers, marinas, bulkheads, and submerged land leases.

The Alabama Department of Environmental Management (ADEM) is responsible for coastal 

area permitting, regulatory, and enforcement functions. Most programs of the ADCNR Coastal 
Gulf of Mexico G&G Activities Programmatic EIS B-53

Section that require environmental permits or enforcement functions are carried out by the ADEM, 

with the exception of submerged land issues. The ADEM is responsible for all permit, enforcement, 

regulatory, and monitoring activities, and the adoption of rules and regulations to carry out the 

ACAMP. The ADEM must identify specific uses or activities that require a State permit to be 

consistent with the coastal policies noted above and the more detailed rules and regulations 

promulgated as part of the ACAMP. Under the ACAA, State agency activities must be consistent 

with ACAMP policies and ADEM findings. Furthermore, ADEM must make a direct permit-type 

review for uses that are not otherwise regulated at the State level. The ADEM also has authority to 

review local government actions and to assure that local governments do not unreasonably restrict 

or exclude uses of regional benefit. Ports and major energy facilities are designated as uses of 

regional benefit. The ADCNR Lands Division manages all lease sales of State submerged lands 

and regulates structures placed on State submerged lands.

Local governments have the option to participate in the ACAMP by developing local codes, 

regulations, rules, ordinances, plans, maps, or any other device used to issue permits or licenses. If 

these instruments are certified to be consistent with ACAMP, the ADEM may allow the local 

government to administer them by delegating its permit authority, thereby eliminating the need for 

ADEM’s case-by-case review.

The South Alabama Regional Planning Commission provides ongoing technical assistance 

to the ADCNR for Federal consistency, clearinghouse review, and public participation procedures. 

Uses subject to the Alabama’s CZM program are divided into regulated and nonregulated 

categories. Regulated uses are those that have a direct and significant impact on the coastal areas. 

These uses require a State permit or are required by Federal law to be consistent with the 

management program. Uses that require a State permit must receive a certificate of compliance. 

Nonregulated uses are those activities that have a direct and significant impact on the coastal areas 

that do not require a State permit or Federal consistency certification. Nonregulated uses must be 

consistent with ACAMP and require local permits to be administered by ADEM.

BOEM developed coordination procedures with the State for submittal of offshore lease sale 

consistency determinations and plans of operation. BOEM and the State of Alabama have revised 

CZM consistency information for OCS plans, permits, and licenses to conform to the revised CZM 

regulations effective January 8, 2001 (updated on January 5, 2006), and have incorporated 

streamlining improvements into the latest NTLs (NTLs 2008-G04, 2009-G27, and 2015-N01). 

Federal consistency for right-of-way pipelines is addressed in NTL 2007-G20.

The State of Alabama requires an adequate description, objective, and schedule for the 

project; site-specific information on the onshore support base, support vessels, shallow hazards, 

oil-spill response, wastes and discharges, transportation activities, and air emissions; and a Federal 

consistency certification, assessment, and findings. The State’s requirements for Federal 

consistency review are based specifically on the USDOI’s regulations at 30 CFR parts 250, 254, 

256, and 550, and NOAA’s Federal consistency requirements at 15 CFR part 930. BOEM is 

continuing a dialogue with the State of Alabama on reasonably foreseeable coastal effects 
B-54 Protective Measures and Mitigation and Regulatory Requirements

associated with pipelines and other permits, and the results of these discussions will be incorporated 

into future updates of BOEM’s permitting procedures and/or NTLs.

3.1.3 State of Mississippi Coastal Management Program

The Mississippi Coastal Program (MCP) is administered by the Mississippi Department of 

Marine Resources. The MCP is built around several enforceable goals that promote comprehensive 

management of coastal resources and encourage a balance between environmental 

protection/preservation and development in the coastal zone. The primary coastal management 

statute is the Coastal Wetlands Protection Law. Other major features of the MCP include statutes 

related to fisheries, air and water pollution control, surface and groundwater, cultural resources, and 

the disposal of solid waste in marine waters. The Department of Marine Resources, the Department 

of Environmental Quality, and the Department of Archives and History are identified collectively as 

the “coastal program agencies.” Mississippi manages coastal resources through regulation and by 

promoting activities that use resources in compliance with the MCP. The State developed a coastal 

wetlands use plan, which includes designated use districts in coastal wetlands and Special 

Management Area Plans that steer development away from fragile coastal resources and help to 

resolve user conflicts.

For the purposes of the coastal program, the coastal zone encompasses the three coastal 

counties of Hancock, Harrison, and Jackson and all coastal waters. The Mississippi Gulf Coast has 

594 km (359 mi) of shoreline, including the coastlines of offshore barrier islands (Cat, Ship, Horn, 

and Petit Bois Islands). According to NOAA, there are no approved local CMPs for the State of 

Mississippi. The Southern Mississippi Planning and Development District serves in an advisory 

capacity to the State’s coastal agencies.

BOEM developed coordination procedures with the State for submittal of offshore lease sale 

consistency determinations and plans of operation. BOEM and the State of Mississippi revised CZM 

consistency information for OCS plans, permits, and licenses to conform to the revised CZM 

regulations effective January 8, 2001 (updated on January 5, 2006), and have incorporated 

streamlining improvements into the latest NTLs (NTLs 2008-G04, 2009-G27, and 2015-N01). 

Federal consistency for right-of-way pipelines is addressed in NTL 2007-G20.

The State of Mississippi requires an adequate description, objective, and schedule for the 

project; site-specific information on the onshore support base, support vessels, shallow hazards, 

oil-spill response, wastes and discharges, transportation activities, and air emissions; and a Federal 

consistency certification, assessment, and findings. The State’s requirements for Federal 

consistency review are based specifically on the USDOI’s regulations at 30 CFR parts 250, 254, 

256, and 550, and NOAA’s Federal consistency requirements at 15 CFR part 930. BOEM is 

continuing a dialogue with the State of Mississippi on reasonably foreseeable coastal effects 

associated with pipelines and other permits, and the results of these discussions will be incorporated 

into future updates of BOEM’s permitting procedures and/or NTLs.
Gulf of Mexico G&G Activities Programmatic EIS B-55

3.1.4 State of Louisiana Office of Coastal Management

The statutory authority for Louisiana’s coastal zone management program, the Louisiana 

Office of Coastal Management (LOCM), is the State and Local Coastal Resources Management Act 

of 1978 et seq. (Louisiana Administrative Code, Volume 17, Title 43, Chapter 7, Coastal 

Management, June 1990 revised). The State statute puts into effect a set of State coastal policies 

and coastal use guidelines that apply to coastal land and water use decisionmaking. Numerous 

existing State regulations are incorporated into the program, including those concerning oil and gas 

and other mineral operations; leasing of State lands for mineral operations and other purposes; 

hazardous waste and radioactive materials; management of wildlife, fish, other aquatic life, and 

oyster beds; endangered species; air and water quality; and the Louisiana Offshore Oil Port. 

The State statute authorized establishment of Special Management Areas. The Louisiana 

Offshore Oil Port and the Marsh Island Wildlife Refuge have been included as Special Management 

Areas. For purposes of the CZMA, only the portion of the Louisiana Offshore Oil Port within 

Louisiana’s coastal zone is part of the Special Management Area. In April 1989, the Louisiana 

Legislature created the Wetlands Conservation and Restoration Authority, and established a 

Wetlands Conservation and Restoration Trust Fund to underwrite restoration projects. The 

Legislature also reorganized part of the Louisiana Department of Natural Resources by creating the 

Office of Coastal Restoration and Management.

Local governments (parishes) may assume management of uses of local concern by 

developing a local coastal program consistent with the State CMP. The State of Louisiana has 

10 approved local CMPs (Calcasieu, Cameron, Jefferson, Lafourche, Orleans, St. Bernard, 

St. James, Plaquemines, Terrebonne, and St. Tammany Parishes). Two additional parishes, 

St. John the Baptist and St. Charles, have worked towards developing local CMPs. Eight other 

programs (Assumption, Iberia, Livingston, St. Charles, St. Martin, St. Mary, Tangipahoa, and 

Vermilion parishes) have not been formally approved by NOAA. The parish planning and/or permits 

offices often serve as the permitting agency for projects limited to local concern. Parish-level 

programs, in addition to issuing permits for uses of local concern, function as commenting agencies 

to Louisiana’s CZM agency, the LOCM, regarding permitting of uses of State concern.

Appendix C2 of the LOCM outlines the rules and procedures for the State’s local CMP. 

Under the LOCM, parishes are authorized, though not required, to develop local CMPs. Approval of 

the CMPs gives parishes greater authority in regulating coastal development projects that entail 

uses of local concern. Priorities, objectives, and policies of local land use plans must be consistent 

with the policies and objectives of Act 361, the LOCM, and the State guidelines, except for a 

variance adopted in Section IV.D of Appendix C2 of the LOCM. The Secretaries of the Department 

of Natural Resources and Wildlife and Fisheries may jointly rule on an inconsistent local program 

based on local environmental conditions or user practices. State and Federal agencies review 

parish programs before they are adopted.
B-56 Protective Measures and Mitigation and Regulatory Requirements

Louisiana’s coastal use guidelines are based on eight general policies as outlined in the 

Louisiana State and Local Coastal Resources Management Act of 1978. State concerns that could 

be relevant to an OCS lease sale and its possible direct effects or associated facilities and 

non-associated facilities are (1) any dredge and fill activity that intersects more than one water body, 

(2) projects involving the use of State-owned lands or water bottoms, (3) national interest projects, 

(4) pipelines, and (5) energy facility siting and development. Some coastal activities of concern that 

could be relevant to a lease sale are wetland loss due to channel erosion from OCS traffic; activities 

near reefs and topographic highs; activities that might affect endangered, threatened, or 

commercially valuable wildlife; and potential socioeconomic impacts due to offshore development. 

Secondary and cumulative impacts to coastal resources such as onshore facility development, 

cumulative impacts from infrastructure development, salt intrusion along navigation channels, and 

others are of particular concern as well.

Effective August 1993, the LOCM required that any entity applying for permits to conduct 

activities along the coast must notify the landowner of the proposed activity. An affidavit must 

accompany any permit application. Through this regulation, the State strives to minimize coastal 

zone conflicts.

BOEM and the State of Louisiana revised CZM consistency information for OCS plans, 

permits, and licenses to conform to the revised CZM regulations effective January 8, 2001 (updated 

on January 5, 2006), and have incorporated streamlining improvements into the latest NTLs (NTLs 

2008-G04, 2009-G27, and 2015-N01). Federal consistency for right-of-way pipelines is addressed 

in NTL 2007-G20.

The State of Louisiana requires an adequate description, objective, and schedule for the 

project. Also, the State requires site-specific information on the onshore support base, support 

vessels, shallow hazards, oil-spill response, wastes and discharges (including any disposal of 

wastes within the State coastal zone and waters and municipal, parish, or State facilities to be used), 

transportation activities, air emissions, and secondary and cumulative impacts; and a Federal 

consistency certification, assessment, and findings. In addition, the State receives consistency 

reviews on a case-by-case basis for decommissioning activities within OCS Significant Sediment 

Blocks that the State utilizes marine mineral resources for restoration projects. The State’s 

requirements for Federal consistency review are based specifically on the USDOI’s regulations at 

30 CFR parts 250, 254, 256, and 550, and NOAA’s Federal consistency regulations at 15 CFR 

part 930. BOEM is continuing a dialogue with the State of Louisiana on reasonably foreseeable 

coastal effects associated with pipelines and other permits, and the results of these discussions will 

be incorporated into future updates of BOEM’s permitting procedures and/or NTLs.

3.1.5 State of Texas Coastal Management Program

The Texas Coastal Management Program’s (TCMP) Final EIS was published in August 

1996. On December 23, 1996, NOAA approved the TCMP, and the requirements therein were 

made operational as of January 10, 1997. The TCMP is based primarily on the Coastal 
Gulf of Mexico G&G Activities Programmatic EIS B-57

Coordination Act of 1991 (33 Tex. Nat. Res. Code Ann. Ch. 201 et seq.), as amended by House Bill 

3226 (1995), which calls for the development of a comprehensive coastal program based on existing 

statutes and regulations. The Coastal Coordination Act established the geographic scope of the 

program by identifying the program’s inland, interstate, and seaward boundaries. The program’s 

seaward boundary is the State’s territorial seaward limit (3 marine leagues; 9 nmi; 10.4 mi; 16.7 km). 

The State’s inland boundary is based on the State’s Coastal Facilities Designation Line (CFDL). The 

CFDL was developed in response to the Oil Pollution Act of 1990 and delineates areas within which 

oil spills could affect coastal waters or resources. For the purposes of the TCMP, the CFDL has 

been modified to capture wetlands in upper reaches of tidal waters. The geographic scope also 

extends upstream 200 mi (322 km) from the mouths of rivers draining into coastal bays and 

estuaries in order to manage water appropriations on those rivers. The TCMP’s boundaries 

encompass all or portions of 18 coastal counties (Cameron, Willacy, Kenedy, Kleberg, Nueces, San 

Patricio, Aransas, Refugio, Calhoun, Victoria, Jackson, Matagorda, Brazoria, Galveston, Harris, 

Chambers, Jefferson, and Orange), roughly 8.9 million acres (3.6 million hectares) of land and 

water.

Within this coastal zone boundary, the scope of the TCMP’s regulatory program is focused 

on the direct management of 16 generic “Areas of Particular Concern,” called coastal natural 

resource areas (CNRAs). The CNRAs are associated with valuable coastal resources or with 

vulnerable or unique coastal areas, and include the following: waters of the open GOM; waters 

under tidal influence; submerged lands; coastal wetlands; seagrasses; tidal sand and mud flats; 

oyster reefs; hard substrate reefs; coastal barriers; coastal shore areas; GOM beaches; critical dune 

areas; special hazard areas; critical erosion areas; coastal historic areas; and coastal preserves.

The State has designated the WPA as the geographical area in which Federal consistency 

will apply outside of the coastal boundary. The TCMP also identifies Federal lands excluded from 

the State’s coastal zone, such as USDOD facilities and wildlife refuges.

Land and water uses subject to the TCMP include the siting, construction, and maintenance 

of electric-generating and transmission facilities; oil and gas exploration and production; and the 

siting, construction, and maintenance of residential, commercial, and industrial development on 

beaches, critical dune areas, shorelines, and within or adjacent to critical areas and other CNRAs. 

Associated activities subject to the program include canal dredging; filling; placement of structures 

for shoreline access and shoreline protection; on-site sewage disposal, stormwater control, and 

waste management for local governments and municipalities; the siting, construction, and 

maintenance of public buildings and public works such as dams, reservoirs, flood control projects, 

and associated activities; the siting, construction, and maintenance of roads, highways, bridges, 

causeways, airports, railroads, and non-energy transmission lines and associated activities; certain 

agricultural and silvicultural activities; water impoundments and diversions; and the siting, 

construction, and maintenance of marinas, State-owned fishing cabins, artificial reefs, public 

recreational facilities, structures for shoreline access and shoreline protection, boat ramps, and 

fishery management measures in the GOM.
B-58 Protective Measures and Mitigation and Regulatory Requirements

The TCMP is a networked program implemented primarily through 8 State agencies, 18 local 

governments, and the Coastal Coordination Advisory Committee (Committee). The program relies 

on direct State control of land and water uses, although local governments will implement State 

guidelines related to beach and dune management. Implementation and enforcement of the coastal 

policies is primarily the responsibility of the networked agencies and local governments through their 

existing statutes, regulatory programs, or other authorizations. Networked agencies include the 

General Land Office/School Land Board, Texas Commission on Environmental Quality, Railroad 

Commission of Texas, Texas Parks and Wildlife Commission, Texas Department of Transportation, 

Texas Water Development Board, Texas State Soil and Water Conservation Board, and Texas Sea 

Grant College Program at Texas A&M University. Other members on the Council include four 

gubernatorial appointees: (1) a coastal business representative; (2) an agriculture representative; 

(3) a local elected official; and (4) a coastal citizen. Similarly, 18 county and municipal governments, 

in counties with barrier islands, are networked entities with responsibilities for program 

implementation vis-a-vis beaches and dunes.

Regulations, programs, and expertise of State, Federal, and local government entities are 

linked to the management of Texas CNRAs in the TCMP. Local governments are notified of relevant 

TCMP decisions, including those that may conflict with local land-use plans or zoning ordinances. 

The Committee includes a local government representative as a full-voting member. An additional 

local government representative can be added to the Committee as a non-voting member for special 

local matters under review. The Committee established a permanent advisory committee to ensure 

effective communication for local governments with land-use authority.

In 1994, BOEM entered into an MOU with the Texas General Land Office to address mineral 

resource management responsibilities, encourage cooperative efforts, and promote consistent 

regulatory practices. The MOU, which encompasses a broad range of issues and processes, 

outlines the responsibilities and cooperative efforts, including leasing and CZMA review processes, 

agreed to by the respective agencies. Effective January 10, 1997, all operators were required to 

submit to BOEM certificates of consistency with the TCMP for proposed operations in the WPA.

BOEM developed coordination procedures with the State of Texas for submittal of offshore 

lease sale consistency determinations and plans of operation. The WPA Lease Sale 168 was 

BOEM’s first Federal action subject to State consistency review. BOEM and the State of Texas 

revised CZM consistency information for OCS plans, permits, and licenses to conform to the revised 

CZM regulations that were effective January 8, 2001 (updated on January 5, 2006), and have 

incorporated streamlining improvements into the latest NTLs (NTLs 2008-G04, 2009-G27, and 

2015-N01).

The State of Texas requires an adequate description, objective, and schedule for the project; 

site-specific information on the onshore support base, support vessels, shallow hazards, oil-spill

response, wastes and discharges, transportation activities, and air emissions; and a Federal 

consistency certification, assessment, and findings. The State’s requirements for Federal 

consistency review are based specifically on the USDOI’s regulations at 30 CFR parts 250, 254, 
Gulf of Mexico G&G Activities Programmatic EIS B-59

256, and 550, and NOAA’s Federal consistency regulations at 15 CFR part 930. BOEM will be 

continuing a dialogue with the State of Texas on reasonably foreseeable coastal effects for pipelines 

and other permits, and the results of these discussions will be incorporated into future updates of 

this agency’s NTLs and/permitting procedures.

4 REFERENCES CITED

Baker, K., D. Epperson, G. Gitschlag, H. Goldstein, J. Lewandowski, K. Skrupky, B. Smith, and 

T. Turk. 2013. National standards for a protected species observer and data management

program: A model using geological and geophysical surveys. 81 pp.

Barkaszi, M.J., M. Butler, R. Compton, A. Unietis, and B. Bennet. 2012. Seismic survey mitigation 

measures and marine mammal observer reports. U.S. Dept. of the Interior, Bureau of Ocean 

Energy Management, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study BOEM 

2012-015. 28 pp. + apps.

Bingham, G. 2011. Status and applications of acoustic mitigation and monitoring systems for 

marine mammals: Workshop proceedings; November 17-19, 2009, Boston, MA. U.S. Dept. of 

the Interior, Bureau of Ocean Energy Management, Regulation, and Enforcement, Gulf of 

Mexico OCS Region, New Orleans, LA. OCS Study BOEMRE 2011-002. 384 pp.

Compton, R., L. Goodwin, R. Handy, and V. Abbot. 2007. A critical examination of worldwide 

guidelines for minimising the disturbance to marine mammals during seismic surveys. Marine 

Policy 32(3):255-262.

Council on Environmental Quality. 1997. Considering cumulative effects under the National 

Environmental Policy Act. Internet website: https://ceq.doe.gov/publications/

cumulative_effects.html. Accessed October 20, 2015.

Federal Register. 1996. Executive Order 12989 – Economy and efficiency in government 

procurement through compliance with certain Immigration and Naturalization Act provisions. 

61 FR 6091, pp. 6091-6093. February 13, 1996.

Federal Register. 1998. Executive Order 13089 – Coral reef protection. 63 FR 32701, 

pp. 32701-32703. June 11, 1998.

Federal Register. 2000a. Executive Order 13158 – Marine protected areas. 65 FR 34909, 

pp. 34909-34911. May 26, 2000.

Federal Register. 2000b. Coastal Zone Management Act Federal Consistency Regulations. 65 FR 

77124, pp. 77124-77175. December 8, 2000.

Federal Register. 2001. Executive Order 13186 – Responsibilities of federal agencies to protect 

migratory birds. 66 FR 3583, pp. 3853-3856. January 10, 2001.

Federal Register. 2006. Coastal Zone Management Act federal consistency regulations. 

71 FR 788, pp. 788-831. January 5, 2006.
B-60 Protective Measures and Mitigation and Regulatory Requirements

Federal Register. 2010a. General provisions; revised list of migratory birds. 75 FR 9282, 

pp. 9282-9314. March 1, 2010.

Federal Register. 2010b. Executive Order 13547 – Stewardship of the ocean, our coasts, and the 

Great Lakes. 75 FR 43023, pp. 43023-43027. July 19, 2010.

Federal Register. 2013. Outer Continental Shelf (OCS) geological and geophysical exploration 

activities in the Gulf of Mexico. 78 FR 27427, pp. 27427-27430. May 10, 2013.

Hedgeland, D., R. Wyatt, and C. Rypdal. 2012. Operational improvements in the use of passive 

acoustic monitoring of marine mammals at sea during seismic surveys. 2012 SPE/APPEA 

International Conference on Health, Safety, and Environment in Oil and Gas Exploration and 

Production (Perth, Australia). SPE 157549. 6 pp.

International Association of Geophysical Contractors. 2011. Appendix B: IAGC recommended 

mitigation measures for cetaceans during geophysical operations (June 2011). In: 

Environmental manual for worldwide geophysical operations. 2013 ed.

Nowacek, D.P., K. Bröker, G. Donovan, G. Gailey, R. Racca, R.R. Reeves, A.I. Vedenev, 

D.W. Weller, and B.L. Southall. 2013. Responsible practices for minimizing and monitoring 

environmental impacts of marine seismic surveys with an emphasis on marine mammals. 

Aquatic Mammals 39(4):356. 

Parsons, E.C.M., S.J. Dolman, M. Jasny, N.A. Rose, M.P. Simmonds, and A.J. Wright. 2009. 

A critique of the UK’s JNCC seismic survey guidelines for minimising acoustic disturbance to 

marine mammals: Best practice? Marine Pollution Bulletin 58:643-651.

South Atlantic Fishery Management Council. 2011. What is a marine protected area? Internet 

website: http://www.safmc.net/managed-areas/marine-protected-areas. Accessed May 12, 

2015.

U.S. Dept. of the Army, Corps of Engineers, Mobile District. 2012. Nationwide permits. Internet 

website: http://www.sam.usace.army.mil/Missions/Regulatory/NWP.aspx. Accessed May 16,

2015.

U.S. Dept. of the Interior, Bureau of Ocean Energy Management. 2012. Guidelines for Providing 

Geological and Geophysical, Hazards, and Archaeological Information Pursuant to 30 CFR 

part 585. 

U.S. Dept. of the Interior, Bureau of Ocean Energy Management. 2013. Regulatory framework: 

Overview of BOEM’s regulatory framework. Internet website: http://www.boem.gov/RegulatoryDevelopment-Policy-and-Guidelines/. Accessed September 4, 2013.

U.S. Dept. of the Interior, Minerals Management Service. 2007. Guide to the OCS alternative 

energy final programmatic environmental impact statement (EIS). Internet website: 

https://www.boem.gov/Renewable-Energy-Program/Regulatory-Information/Guide-To-EIS.aspx. 

Accessed March 30, 2017.
Gulf of Mexico G&G Activities Programmatic EIS B-61

U.S. Dept. of the Interior, Minerals Management Service. 2009. Memorandum of Understanding 

between the Dept. of the Interior U.S. Minerals Management Service and the Dept. of the Interior 

U.S. Fish and Wildlife Service regarding implementation of Executive Order 13186, 

“Responsibilities of Federal Agencies to Protect Migratory Birds." Internet website: 

https://www.boem.gov/MMS-FWS-MBTA-MOU/. Accessed March 30, 2017.

Wright, A.J. and A.M. Cosentino. 2015. JNCC guidelines for minimising the risk of injury and 

disturbance to marine mammals from seismic surveys: We can do better. Marine Pollution 

Bulletin 100(1):231-239.

Weir, C.R. and S.J. Dolman. 2007. Comparative review of the regional marine mammal mitigation 

guidelines implemented during industrial seismic surveys, and guidance towards a worldwide 

standard. Journal of International Wildlife Law & Policy 10:1-27.

Gulf of Mexico G&G Activities Programmatic EIS B-63

ATTACHMENT 1: SEISMIC AIRGUN SURVEY PROTOCOL 

The requirements of NTL 2016-BOEM-G02 (“Implementation of Seismic Survey Mitigation 

Measures and Protected Species Observer Program”) are summarized below.

Ramp-Up Procedures

The intent of ramp-up is to warn marine mammals and sea turtles of pending seismic 

operations and to allow sufficient time for those animals to leave the immediate vicinity. Under 

normal conditions, animals sensitive to these activities are expected to move out of the area. For all 

seismic surveys, including airgun testing, the ramp-up procedures described here should be used to 

allow any marine mammal or sea turtle to depart the exclusion zone before seismic surveying 

begins.

Measures to conduct ramp-up procedures during all seismic airgun survey operations in 

water depths >200 m (656 ft) in the WPA and CPA and in all water depths in the EPA, including 

airgun testing, are as follows: 

(1) Visually monitor the exclusion zone and adjacent waters for the absence of 

marine mammals and sea turtles for at least 30 minutes before initiating rampup procedures. If none are detected, ramp-up procedures may be initiated. 

Operators may not initiate ramp-up procedures at night or when the exclusion 

zone cannot be visually monitored for marine mammals and sea turtles if the 

minimum source level drops below 160 dB re 1 μPa-m (rms) or any other 

Level B acoustic thresholds set by NMFS for behavioral harassment (i.e., 

Level B harassment). Altering the survey vessel’s course to water depths 

<200 m (656 ft) in the CPA and WPA to circumvent ramp-up requirements of 

the 200-m (656-ft) isobath will be considered noncompliant.

(2) Initiate ramp-up procedures by firing a single airgun. The preferred airgun to 

begin with should be the smallest airgun, in terms of energy output (dB) and 

volume (in3

).

(3) Continue ramp-up by gradually activating additional airguns over a period of at 

least 20 minutes, but no longer than 40 minutes, until the desired operating 

level of the airgun array is obtained.

(4) Immediately shut down all airguns, ceasing seismic operations any time a whale 

is detected entering or within the exclusion zone. Ramp-up of airguns and 

seismic operations may recommence only when the exclusion zone has been 

visually inspected for at least 30 minutes to ensure the absence of marine 

mammals and sea turtles.

(5) Operators may reduce the source level of the airgun array, using the same shot 

interval as the seismic survey, to maintain a minimum source level of 160 dB re 

1 μPa-m (rms) (or any other Level B acoustic threshold set by NMFS) for the 
B-64 Protective Measures and Mitigation and Regulatory Requirements

duration of certain activities (thresholds stated here [e.g., the 160 dB Level B 

harassment threshold] may be superseded by any future thresholds set by 

NMFS). By maintaining the minimum source level, operators will not be 

required to conduct the 30-minute visual clearance of the exclusion zone before 

ramping back up to full output. Activities appropriate for maintaining the 

minimum source level are as follows:

(a) all turns between transect lines, when a survey using the full array is being 

conducted immediately prior to the turn and will be resumed immediately 

after the turn; and 

(b) unscheduled, unavoidable maintenance of the airgun array that requires the 

interruption of a survey to shut down the array. The survey should be 

resumed immediately after repairs are completed. There may be other 

occasions when this practice is appropriate, but use of the minimum source 

level to avoid the 30-minute visual clearance of the exclusion zone is only 

for events that occur during a survey using the full power array. The 

minimum sound source level is not to be used to allow a later ramp-up after 

dark or in conditions when ramp-up would not otherwise be allowed.

Exclusion Zone

The exclusion zone is the primary mechanism to minimize the potential for injury (Level A 

harassment) of marine mammals to the maximum extent practicable. The operator will monitor an 

exclusion zone within a radius of 500 m (1,640 ft). The exclusion zone means the area at and below 

the sea surface with a radius of 500 m (1,640 ft) surrounding the center of an airgun array and the 

area within the immediate vicinity of the survey vessel. Each survey vessel must maintain its own 

exclusion zone and cannot enter another vessel’s exclusion zone to avoid the mitigation measures 

set forth in their permit.

While there are no noise exposure criteria for sea turtles, the protocol is expected to similarly 

reduce the risk of injury in sea turtles.

Shutdown Requirements

(1) In the event that any whale(s) (defined as baleen, beaked, sperm, or dwarf and 

pygmy sperm whales) observed within the exclusion zone, whether due to the 

whale’s movement, the vessel’s movement, or because the whale surfaced 

inside the exclusion zone, the PSO will call for the immediate shutdown of the 

seismic operation, including airgun firing (the vessel may continue on its course

but all airgun discharge’s must cease).

(2) Shutdown would not be required for manatees or marine mammals in the 

Family Delphinidae (this includes, among others, killer whales, pilot whales, and 

all of the "dolphin" species).
Gulf of Mexico G&G Activities Programmatic EIS B-65

(3) The vessel operator must comply immediately with such a call by the PSO. Any 

disagreement or discussion should occur only after shutdown.

(4) When no marine mammals or sea turtles are sighted for at least a 30 minutes, 

ramp-up of the source array may begin. Ramp-up cannot begin unless 

conditions allow the sea surface to be visually inspected for marine mammals 

and sea turtles for 30 minutes prior to commencement of ramp-up (unless 

passive acoustic monitoring [PAM] is used). Thus, ramp-up cannot begin after 

dark or in conditions that prohibit visual inspection (e.g., fog and rain) of the 

exclusion zone after a shutdown.

(5) Any shutdown due to a whale(s) (baleen, beaked, sperm, or dwarf and pygmy 

sperm whales) sighting within the exclusion zone must be followed by a 

30-minute all-clear period and then a standard, full ramp-up. Any shutdown for 

other reasons, including mechanical or electronic failure, resulting in the 

cessation of the acoustic source for a period longer than 20 minutes, must be 

followed by full ramp-up procedures. In recognition of occasional, short periods 

of the cessation of airgun firing for a variety of reasons, periods of airgun 

silence not exceeding 20 minutes in duration will not require ramp-up for the 

resumption of seismic operations if

(a) visual surveys are continued diligently throughout the silent period (requiring 

daylight and reasonable sighting conditions); and 

(b) no whales, other marine mammals, or sea turtles are observed in the 

exclusion zone.

If whales, other marine mammals, or sea turtles are observed in the exclusion 

zone during the short silent period, resumption of seismic survey operations 

must be preceded by ramp-up.

Protected Species Observer Program

Basic Requirements

Visual observers who have completed a PSO training program as described below are 

required on all seismic vessels conducting operations in water depths >200 m (656 ft) throughout the 

GOM. Visual observers are required on all seismic vessels conducting operations in OCS water 

depths <200 m (656 ft) in the GOM waters east of 88.0° W. longitude.

(1) Operators may engage trained third-party observers, utilize crew members after 

training as observers, or use a combination of third-party and crew observers.

(2) All PSOs must have completed a PSO training course. BOEM and BSEE will

not sanction particular trainers or training programs. However, basic training 

criteria have been established. All training programs offering to fulfill the PSO 

training requirements must
B-66 Protective Measures and Mitigation and Regulatory Requirements

(a) furnish to BSEE, a course information packet that includes the name and 

qualifications of the instructor(s), the course outline or syllabus, and course 

reference material;

(b) furnish each trainee with a document stating successful completion of the 

course; and

(c) provide BSEE with names, affiliations, and dates of course completion of 

trainees.

(3) At least two PSOs will be required on seismic airgun vessels to monitor the 

exclusion zone at all times during daylight hours (dawn to dusk) when seismic 

operations are being conducted, unless conditions (e.g., fog, rain, and 

darkness) make sea surface observations impossible. If conditions deteriorate 

during daylight hours such that sea surface observations are halted, visual 

observations must resume as soon as conditions permit.

(4) The PSO will monitor the exclusion zone (according to the requirements of the 

following elements) for protected species and will observe and document their 

presence and behavior, searching the area around the vessel using hand-held 

reticule binoculars and the unaided eye.

(5) If a marine mammal or sea turtle is observed, the PSO should note and monitor 

the position until the animal dives or moves out of visual range.

(6) The PSO must prepare an observer effort report and survey report for each day 

during which seismic operations are conducted and airguns are being 

discharged. These reports are to be submitted to BSEE on the 1st and 15th of 

each month.

(7) The following schedule limitations will apply to PSOs during survey activities:

(a) other than brief alerts to bridge personnel of maritime hazards, no additional 

duties can be assigned to PSOs during their watch;

(b) a watch will be no longer than 4 consecutive hours;

(c) a break of at least 2 hours must occur between 4-hour watches and no 

other duties will be assigned during this period; and 

(d) a PSO’s combined watch schedule must not exceed 12 hours during a 

24-hour period.

Reporting

The importance of accurate and complete reporting of the results of the mitigation measures 

cannot be overstated. Only through diligent and careful reporting can BOEM, and subsequently 

NMFS, determine the need for and effectiveness of mitigation measures. Information on observer 

effort and seismic operations is as important as animal sighting and behavior data. In order to 
Gulf of Mexico G&G Activities Programmatic EIS B-67

accommodate various vessels’ bridge practices and preferences, vessel operators and observers 

may design data-reporting forms in whatever format they deem convenient and appropriate. 

Alternatively, observers or vessel operators may adopt the United Kingdom’s Joint Nature 

Conservation Committee forms (available at http://www.jncc.gov.uk). At a minimum, the following 

items should be recorded and included in reports to BOEM.

Observer Effort Report: BOEM requires the submission of observer effort reports to BSEE 

on the 1st and 15th of each month for each day seismic acquisition operations are conducted. 

These reports must include the following information:

(1) vessel name; 

(2) observers’ names and, affiliations; 

(3) survey type (e.g., site, 3D, and 4D); 

(4) BOEM permit number (for “off-lease seismic surveys”) or OCS lease number 

(for “on-lease seismic surveys”); 

(5) date; 

(6) time and latitude/longitude when daily visual survey began; 

(7) time and latitude/longitude when daily visual survey ended; and 

(8) average environmental conditions while on each visual survey rotation and 

session as well as when any conditions change during the rotation, each 

session, including 

(a) wind speed and direction; 

(b) sea state (glassy, slight, choppy, rough, or Beaufort scale); 

(c) swell (low, medium, high, or swell height in meters); and 

(d) overall visibility (poor, moderate, good). 

Survey Report: BOEM requires the submission of survey reports to BSEE on the 1st and 

15th of the month for each day seismic acquisition operations are conducted and airguns are 

discharged. These reports must include the following information:

(1) vessel name; 

(2) survey type (e.g., site, 3D, and 4D); 

(3) BOEM permit number (for “off-lease seismic surveys”) or OCS lease number 

(for “on-lease seismic surveys”), if applicable; 

(4) date; 
B-68 Protective Measures and Mitigation and Regulatory Requirements

(5) time pre-ramp-up survey begins; 

(6) observations of marine mammals and sea turtles seen during pre-ramp-up 

surveys; 

(7) time ramp-up begins;

(8) observations of marine mammals and sea turtles seen during ramp-up; 

(9) time that sound source (airguns or non-airgun HRG equipment) is operating at 

the desired intensity;

(10) observations of marine mammals and sea turtles seen during surveys; 

(11) if marine mammals or sea turtles were seen, was any action taken (e.g., survey 

delayed and airguns shut down)?

(12) reason that marine mammals and sea turtles might not have been observed 

(e.g., swell, glare, and fog); and 

(13) time that sound source (airgun array or non-airgun HRG equipment) stops 

firing. 

Sighting Report: BOEM will require the submission of reports to BSEE for marine 

mammals and sea turtles sighted during seismic and non-airgun HRG surveys on the 1st and 15th of 

each month, except as indicated below. These reports are in addition to any reports required as a 

condition of the geophysical permit and must include the following information: 

(1) vessel name; 

(2) survey type (e.g., site, 3D, and 4D); 

(3) BOEM permit number (for “off-lease seismic surveys”) or OCS lease number 

(for “on-lease seismic surveys”); 

(4) date; 

(5) time; 

(6) watch status (Were you on watch or was this sighting made opportunistically by 

you or someone else?); 

(7) observer or person who made the sighting; 

(8) latitude/longitude of vessel; 

(9) bearing of vessel (true compass direction); 

(10) bearing (true compass direction) and estimated range to animal(s) at first 

sighting; 

(11) water depth (meters); 
Gulf of Mexico G&G Activities Programmatic EIS B-69

(12) species (or identification to lowest possible taxonomic level); 

(13) certainty of identification (sure, most likely, best guess); 

(14) total number of animals; 

(15) number of juveniles; 

(16) description (as many distinguishing features as possible of each individual 

seen, including length, shape, color and pattern, scars or marks, shape and size 

of dorsal fin, shape of head, and blow characteristics); 

(17) direction of animal’s travel – compass direction; 

(18) direction of animal’s travel – related to the vessel (drawing preferably); 

(19) behavior (as explicit and detailed as possible; note any observed changes in 

behavior); 

(20) activity of vessel; 

(21) airguns firing? (yes or no); and 

(22) closest distance (meters) to animal(s) from center of airgun or airgun array 

(whether firing or not). 

Note: If this sighting was of a marine mammal or sea turtle within the exclusion zone 

that resulted in a shutdown of the airguns, include in the sighting report the observed behavior of 

the animal(s) before shutdown, the observed behavior following shutdown (specifically noting any 

change in behavior), and the length of time between shutdown and subsequent ramp-up to resume 

the seismic survey (note if seismic survey was not resumed as soon as possible following 

shutdown). Send this report to BOEM within 24 hours of the shutdown. These sightings should 

also be included in the first regular semi-monthly report following the incident.

Additional information, important points, and comments are encouraged. All reports will be 

submitted to BOEM on the 1st and 15th of each month (with one exception, noted above). Forms 

should be scanned (or typed) and sent via email to BOEM.

Please note that these marine mammal and sea turtle reports are in addition to any reports 

required as a condition of the geophysical permit.

Borehole Seismic Surveys

Borehole seismic differs from conventional exploration seismic by the placement of the 

acoustic receivers in the borehole of a well as opposed to towed streamers or ocean bottom 

placement of receivers (i.e., nodes or cables). (Note: A complete description of borehole surveys 

can be found in Appendix F, Section 1.1.5). Because of this key difference, the following mitigation 

measures apply only to borehole surveys:
B-70 Protective Measures and Mitigation and Regulatory Requirements

(1) During daylight hours, when visual observations of the exclusion zone are being 

performed as required in this NTL, borehole seismic operations will not be 

required to ramp-up for shutdowns of 30 minutes or less in duration as long as 

no whales, other marine mammals, or sea turtles are observed in the exclusion 

zone (500 m [1,640 ft]) during the shutdown. If a whale, other marine mammal, 

or sea turtle is sighted in the exclusion zone, ramp-up is required and may 

begin only after visual surveys confirm that the exclusion zone has been clear 

for 30 minutes.

(2) During nighttime or when conditions prohibit visual observation of the exclusion 

zone, ramp-up will not be required for shutdowns of 20 minutes or less in 

duration.

(3) For borehole seismic surveys that utilize PAM during nighttime and periods of 

poor visibility, ramp-up is not required for shutdowns of 30 minutes or less.

(4) Nighttime or poor visibility ramp-up is allowed only when PAM is used to ensure 

that no whales are present in the exclusion zone (as for all other seismic 

surveys). Operators are strongly encouraged to acquire the survey in daylight 

hours when possible.

(5) During daylight hours, PSOs must be used as required in this NTL, and may be 

stationed on the source boat or on the associated drilling rig or platform if a 

clear view of the sea surface in the exclusion zone and adjacent waters is 

available.

(6) All other mitigations and provisions for seismic surveys as set forth in this NTL 

will apply to borehole seismic surveys.

(7) Reports should reference a Plan Control Number, OCS Lease Number, 

Area/Block, and Borehole Number or BOEM permit number, as applicable.

Passive Acoustic Monitoring

Inclusion of PAM does not relieve an operator of any of the mitigations (including PSOs) 

with the following exception: monitoring for whales with PAM will allow ramp-up and the 

subsequent start of a seismic airgun survey during times of reduced visibility (e.g., darkness, fog, 

and rain) when such ramp-up otherwise would not be permitted using only PSOs. If PAM is used, 

the operator must include an assessment of the usefulness, effectiveness, and problems 

encountered with the use of that method of marine mammal detection in the reports. A description 

of the PAM system, software used, and Monitoring Plan should be reported to BSEE at the 

beginning of its use.
Gulf of Mexico G&G Activities Programmatic EIS B-71

ATTACHMENT 2: NON-AIRGUN HRG SURVEY PROTOCOL 

The Non-Airgun HRG Survey Protocol applies to HRG surveys conducted using only 

acoustic sources such as side-scan sonar; boomers, sparkers, and CHIRP subbottom profilers; and 

single-beam and multibeam depth sounders (Appendix F, Section 1.3). Other HRG surveys using 

airguns are excluded from this protocol and must comply instead with the Seismic Airgun Survey 

Protocol. The non-airgun HRG Survey Protocol requirements can be summarized as follows:

• non-airgun HRG surveys in which one or more active acoustic sources will be 

operating at frequencies ≤200 kHz, a pre-survey clearance period (of marine 

mammals and sea turtles) of 30 minutes before start-up or after a shutdown for 

sperm, Bryde’s, beaked, Kogia whale(s) or manatee(s) that are within the 

exclusion zone; 

• one PSO and 200-m (656-ft) exclusion zone monitoring for non-airgun HRG 

surveys in all water depths throughout the GOM operating at or below 200 kHz; 

and 

• if seismic airguns are used for HRG surveys, these surveys would be subject to 

the Seismic Airgun Survey Protocol.

Exclusion Zone

All non-airgun HRG surveys conducted with one or more acoustic sources operating at 

frequencies ≤200 kHz will be required to establish an exclusion zone. An exclusion zone is not 

required for non-airgun HRG surveys in which all acoustic sources would operate at frequencies 

>200 kHz. The exclusion zone would be a 200-m (656-ft) radius zone around the sound source.

Protected Species Observer Program

All non-airgun HRG surveys having an exclusion zone (i.e., those conducted using one or 

more acoustic sources operating at or below 200 kHz) must use PSOs to monitor the exclusion 

zone. The PSOs can be trained crew members and/or third-party observers. A PSO for an HRG 

survey is defined as someone who has successfully completed a PSO training course.

Visual Monitoring Requirements

The following visual monitoring requirements apply only to non-airgun HRG surveys in which 

at least one acoustic source will operate at frequencies ≤200 kHz. If there are no acoustic sources 

operating at frequencies ≤200 kHz, there will be no exclusion zone and there are no requirements 

for PSOs. However, all non-airgun HRG operators must comply with all other mitigation measures 

applicable to all G&G surveys described in Chapter 2 of this Programmatic EIS.

Visual monitoring of the exclusion zone must be conducted by trained PSOs. At least one 

PSO would be required on watch aboard HRG survey vessels at all times during daylight hours 

(i.e., from approximately 30 minutes before sunrise to 30 minutes after sunset) when survey 
B-72 Protective Measures and Mitigation and Regulatory Requirements

operations are being conducted, unless conditions (e.g., fog, rain, and darkness) make sea surface 

observations impossible. If conditions deteriorate during daylight hours such that the sea surface 

observations are halted, visual observations must resume as soon as conditions permit. Ongoing 

activities may continue but may not be initiated under such conditions (i.e., without appropriate 

pre-activity monitoring).

The requirements for PSOs and their roles are as follows:

• At least one PSO will be required on duty at all times to monitor the exclusion 

zone when acoustic sources are operating.

• The PSO(s) will monitor an exclusion zone for protected species and observe 

and document their presence and behavior, searching the area around the 

vessel using handheld reticule binoculars and the unaided eye. For nighttime 

operations, or if operations continue during periods of reduced visibility, 

operators would monitor the waters around the exclusion zone using shipboard 

lighting, enhanced vision equipment, and night-vision equipment.

The following schedule limitations will apply to PSOs during HRG survey activities:

• Other than brief alerts to bridge personnel of maritime hazards, no additional 

duties will be assigned to PSOs during their watch.

• A watch must be no longer than 4 consecutive hours.

• A break of at least 2 hours must occur between 4-hour watches, and no other 

duties will be assigned during this period.

• A PSO’s combined watch schedule must not exceed 12 hours during a 24-hour 

period.

The PSO(s) on duty will look for marine mammals and sea turtles using the naked eye and 

handheld binoculars. The PSO(s) will stand watch in a suitable location that will not interfere with 

navigation or operation of the vessel and that affords an optimal view of the sea surface. The 

PSO(s) will provide 360° coverage surrounding the survey vessel and adjust position(s) 

appropriately to help ensure adequate coverage of the entire area. Observations must be 

consistent, diligent, and free of distractions for the duration of the watch.

Startup and Shutdown Requirements

Monitoring of the exclusion zone must begin no less than 30 minutes prior to start-up and 

continue until operations cease. Immediate shutdown of the acoustic source(s) would occur if any 

sperm, Bryde’s, beaked, Kogia whale(s), or manatee(s) is detected entering or within the exclusion 

zone. Subsequent restart of the equipment may only occur following a confirmation that the 

exclusion zone is clear of all marine mammals and sea turtles for 30 minutes.
Gulf of Mexico G&G Activities Programmatic EIS B-73

Reporting

The importance of accurate and complete reporting of the results of the mitigation measures 

cannot be overstated. Only through diligent and careful reporting can BOEM, and subsequently 

NMFS, determine the need for and effectiveness of mitigation measures. Information on observer 

effort and seismic operations is as important as animal sighting and behavior data. In order to 

accommodate various vessels’ bridge practices and preferences, vessel operators and observers 

may design data reporting forms in whatever format they deem convenient and appropriate. 

Alternatively, observers or vessel operators may adopt the United Kingdom’s Joint Nature 

Conservation Committee forms (available at http://www.jncc.gov.uk). At a minimum, the items below 

should be recorded and included in reports to BOEM. 

Protected Species Observer Reports: Data on all protected species observations must be 

recorded by the PSO based on standard marine mammal observer data collection protocols. This

information must include the following: 

• vessel name; 

• observers’ names, affiliations, and resumes; 

• date; 

• time and latitude/longitude when daily visual survey began; 

• time and latitude/longitude when daily visual survey ended;

• average environmental conditions during visual surveys, including: 

− wind speed and direction; 

− sea state (glassy, slight, choppy, rough, or Beaufort scale); 

− swell (low, medium, high, or swell height in meters); and 

− overall visibility (poor, moderate, good). 

• species (or identification to lowest possible taxonomic level); 

• certainty of identification (sure, most likely, best guess); 

• total number of animals; 

• number of calves and juveniles (if distinguishable); 

• description (as many distinguishing features as possible of each individual seen, 

including length, shape, color and pattern, scars or marks, shape and size of 

dorsal fin, shape of head, and blow characteristics); 

• direction of animal’s travel – related to the vessel (drawing preferably); 
B-74 Protective Measures and Mitigation and Regulatory Requirements

• behavior (as explicit and detailed as possible; note any observed changes in 

behavior); and

• activity of vessel when sighting occurred.

Note: If this sighting was of a marine mammal within the exclusion zone that resulted in a 

shutdown of survey equipment, include in the sighting report the observed behavior of the animal(s) 

before shutdown, the observed behavior following shutdown (specifically noting any change in 

behavior), and the length of time between shutdown and restart of the survey (note if survey was not 

resumed as soon as possible following shutdown). Send this report to BOEM within 24 hours of 

the shutdown. These sightings also should be included in the first regular semi-monthly report 

following the incident. 

Additional information, important points, and comments are encouraged. All reports will be 

submitted to BOEM on the 1st and 15th of each month (with one exception, noted above). Forms 

should be scanned (or typed) and sent via email to BOEM. Please note that these marine mammal 

and sea turtle reports are in addition to any reports required as a condition of the geophysical permit 

or authorization.
APPENDIX C 

SETTLEMENT AGREEMENT 

AND 

STIPULATION TO AMEND SETTLEMENT AGREEMENT

Gulf of Mexico G&G Activities Programmatic EIS C-3 
C-4 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-5 
C-6 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-7 
C-8 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-9 
C-10 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-11
C-12 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-13
C-14 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-15
C-16 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-17
C-18 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-19
C-20 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-21
C-22 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-23
C-24 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-25
C-26 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-27
C-28 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-29
C-30 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-31
C-32 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-33
C-34 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-35
C-36 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-37
C-38 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-39
C-40 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-41
C-42 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-43
C-44 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-45
C-46 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-47
C-48 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-49
C-50 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-51
C-52 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-53
C-54 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-55
C-56 Settlement Agreement and Stipulation to Amend
Gulf of Mexico G&G Activities Programmatic EIS C-57

APPENDIX D 

ACOUSTIC PROPAGATION AND 

MARINE MAMMAL EXPOSURE MODELING

ACOUSTIC PROPAGATION AND 

MARINE MAMMAL EXPOSURE 

MODELING OF GEOLOGICAL AND 

GEOPHYSICAL SOURCES IN THE 

GULF OF MEXICO

2016–2025 Annual Acoustic Exposure Estimates for Marine 

Mammals

Submitted to:

Kimberly Skrupky Warshaw

Bureau of Ocean Energy Management (BOEM)

Authors:

David Zeddies

Mikhail Zykov

Harald Yurk

Terry Deveau

Loren Bailey

Isabelle Gaboury

Roberto Racca

David Hannay

Scott Carr

JASCO Applied Sciences

Suite 202, 32 Troop Ave.

Dartmouth, NS B3B 1Z1 Canada

Phone: +1-902-405-3336

Fax: +1-902-405-3337

www.jasco.com

6 Nov 2015

P001253-001

Document 00976

Version 3.0

Gulf of Mexico G&G Activities Programmatic EIS D-i 

Statement of Disclaimer 

This draft report was reviewed by the BOEM. Approval does not signify that the contents necessarily 

reflect the views and policies of the Bureau, nor does mention of trade names or commercial products 

constitute endorsement or recommendation for use. 

Acknowledgement of Sponsorship

Study concept, oversight, and funding were provided by the US Department of the Interior, Bureau of 

Ocean Energy Management, Environmental Studies Program, Washington, DC under Contract Number 

M14PC00004. 
D-ii Acoustic Propagation and Marine Mammal Exposure Modeling

Suggested citation:

Zeddies, D.G., M. Zykov, H. Yurk, T. Deveau, L. Bailey, I. Gaboury, R. Racca, D. Hannay, and S. Carr. 

2015. Acoustic Propagation and Marine Mammal Exposure Modeling of Geological and Geophysical 

Sources in the Gulf of Mexico: 2016–2025 Annual Acoustic Exposure Estimates for Marine Mammals. 

JASCO Document 00976, Version 3.0. Technical report by JASCO Applied Sciences for Bureau of 

Ocean Energy Management (BOEM). 
Gulf of Mexico G&G Activities Programmatic EIS D-iii

Contents

1. EXECUTIVE SUMMARY ..................................................................................................................1

1.1. Overview........................................................................................................................................................... 1

1.2. Sounds and Marine Mammals........................................................................................................................... 1

1.3. Acoustic Modeling ............................................................................................................................................ 2

1.4. Marine Mammals in the Gulf of Mexico........................................................................................................... 3

1.5. Animal Movement Modeling ............................................................................................................................ 3

1.6. Phase I............................................................................................................................................................... 4

1.7. Phase II: Annual Acoustic Exposure Estimates ................................................................................................ 4

2. PROJECT OVERVIEW ......................................................................................................................5

3. INTRODUCTION..............................................................................................................................6

3.1. The Ocean Soundscape ..................................................................................................................................... 6

3.1.1. Seismic Sources..................................................................................................................................... 6

3.1.1.1. Airguns .................................................................................................................................. 6

3.1.2. High-resolution Sources........................................................................................................................ 6

3.1.2.1. Side-scan Sonar Systems ....................................................................................................... 6

3.1.2.2. Multibeam Echosounders Sonar Systems.............................................................................. 7

3.1.2.3. Sub-bottom Profiler Sonar Systems....................................................................................... 7

3.1.2.4. Boomer Sources..................................................................................................................... 7

3.1.3. Pulsed Versus Non-Pulsed Sounds........................................................................................................ 7

3.2. Acoustic Metrics ............................................................................................................................................... 8

3.3. Use of Sounds by Marine Species..................................................................................................................... 9

3.3.1. Cetacean Hearing ................................................................................................................................10

3.3.1.1. Classification of Cetacean Hearing......................................................................................10

3.4. Potential Effects of Sounds on Marine Mammals...........................................................................................11

3.4.1. Auditory Signal Masking ....................................................................................................................11

3.4.2. Behavioral Disturbance .......................................................................................................................12

3.4.3. Temporary and Permanent Hearing Loss............................................................................................14

3.4.4. Non-Auditory Health Effects ..............................................................................................................15

3.4.5. Reduction of Prey Availability............................................................................................................15

4. MARINE MAMMALS IN THE GULF OF MEXICO .............................................................................17

5. MODELING METHODOLOGY ........................................................................................................19

5.1. Acoustic Source Model ...................................................................................................................................19

5.1.1. Airgun and Airgun Array Modeling Methodology .............................................................................19

5.1.2. Electromechanical Source Modeling—Transducer Beam Theory ......................................................20

5.1.2.1. Circular Transducers............................................................................................................21

5.1.2.2. Rectangular Transducers......................................................................................................22

5.1.2.3. Multibeam Systems..............................................................................................................23

5.2. Acoustic Propagation Modeling......................................................................................................................24

5.2.1. Two Frequency Regimes: RAM vs. BELLHOP .................................................................................24

5.2.2. N×2-D Volume Approximation ..........................................................................................................25

5.2.3. Frequency Dependence: Summing Over 1/3-Octave-Bands...............................................................25

5.2.4. Converting Modeled SEL to rms SPL................................................................................................. 26
D-iv Acoustic Propagation and Marine Mammal Exposure Modeling

5.2.4.1. Background..........................................................................................................................26

5.2.4.2. Fixed Integration Time Window..........................................................................................27

5.3. Animal Movement Modeling for Impact Assessment.....................................................................................27

5.4. Acoustic Exposure Criteria .............................................................................................................................28

5.4.1. Marine Mammal Frequency Weighting Functions..............................................................................29

5.4.2. Injury Exposure Criteria Selection ......................................................................................................32

5.4.3. Behavioral Exposure Criteria Selection ..............................................................................................34

5.4.4. Exposure Estimation............................................................................................................................35

5.4.4.1. Injury Exposure Estimates—cumulative SEL .....................................................................35

5.4.4.2. Injury Exposure Estimates—peak SPL................................................................................35

5.4.4.3. Behavior Exposure Estimates—rms SPL.............................................................................35

5.4.4.4. NMFS Criteria for Injury and Behavior Exposure Estimates—rms SPL.............................35

6. PHASE I: TEST CASE AND TEST SCENARIOS ................................................................................36

6.1. Test Case Acoustic Source Parameters ...........................................................................................................37

6.2. Test Case Environmental Parameters..............................................................................................................40

6.2.1. Modeling Sites.....................................................................................................................................40

6.2.2. Bathymetry ..........................................................................................................................................40

6.2.3. Multi-Layer Geoacoustic Profile.........................................................................................................40

6.2.4. Sound Speed Profile ............................................................................................................................42

6.2.5. Marine Mammals Density Estimates...................................................................................................43

6.2.6. Animal Movement Modeling ..............................................................................................................46

6.3. Test Case Results ............................................................................................................................................46

6.3.1. Acoustic Sources: Levels and Directivity............................................................................................46

6.3.1.1. 8000 in3 Airgun Array..........................................................................................................46

6.3.1.2. Per-Pulse Acoustic Field for Input to ESME .......................................................................49

6.3.1.3. Range to Zero-to-Peak SPL Isopleths..................................................................................49

6.3.2. Simulation Exposure Estimates...........................................................................................................50

6.3.3. Real-world Individual Exposure Estimates.........................................................................................53

6.4. Test Case Exposure Summary.........................................................................................................................55

6.5. Test Scenarios .................................................................................................................................................56

6.5.1. Test Scenario 1: Scaling Modeled Acoustic Exposure Estimates .......................................................56

6.5.1.1. Large-scale Animal Movement............................................................................................56

6.5.1.1.1. Scaling Methods ...............................................................................................57

6.5.1.1.2. Assumptions .....................................................................................................57

6.5.1.1.3. Prey Distribution as an Environmental Attractor..............................................57

6.5.1.1.4. Distribution and Movement Behavior of Modeled Species..............................57

6.5.1.2. Potential Biases in the Modeling Procedure ........................................................................59

6.5.1.2.1. Methods ............................................................................................................59

6.5.1.2.2. Results...............................................................................................................60

6.5.1.3. Summary of Scaling Modeled Acoustic Exposure Results..................................................68

6.5.1.3.1. Large-scale Animal Movement.........................................................................68

6.5.1.3.2. Potential Biases in the Modeling Procedure .....................................................68

6.5.1.3.3. Scaling Short-duration Simulations for Long-duration Operations ..................70

6.5.2. Test Scenario 2: Analysis of Uncertainty in Acoustic and Animal Modeling.....................................70
Gulf of Mexico G&G Activities Programmatic EIS D-v 

6.5.2.1. Acoustic Modeling Uncertainty...........................................................................................71

6.5.2.1.1. Source Characterization Modeling Uncertainty................................................71

6.5.2.1.2. Acoustic Propagation Modeling Uncertainty....................................................72

6.5.2.1.3. Sound Speed Profiles........................................................................................72

6.5.2.1.4. Sound Speed Profile Results.............................................................................78

6.5.2.1.5. Geoacoustics.....................................................................................................84

6.5.2.1.6. Geoacoustic Results..........................................................................................86

6.5.2.1.7. Bathymetry .......................................................................................................91

6.5.2.1.8. Bathymetry Results...........................................................................................92

6.5.2.1.9. Sea State............................................................................................................99

6.5.2.1.10. Summary of Acoustic Uncertainty................................................................100

6.5.2.2. Animal Modeling Uncertainty ...........................................................................................101

6.5.2.2.1. Animal Movement Parameters Uncertainty....................................................101

6.5.2.2.2. Summary of Animal Movement Parameter Uncertainty................................. 102

6.5.2.2.3. Animal Density Estimates Uncertainty...........................................................102

6.5.2.2.4. Animal Density Estimates Uncertainty Results..............................................103

6.5.2.2.5. Summary of Animal Density Estimate Uncertainty........................................107

6.5.2.2.6. Impact of Social Group Size on Exposure Estimates......................................107

6.5.2.2.7. Impact of Social Group Size on Exposure Estimates: Methods......................108

6.5.2.2.8. Impact of Social Group Size on Exposure Estimates: Results........................109

6.5.2.2.9. Summary of Impact of Social Group Size on Exposure Estimates.................112

6.5.2.3. Exposure Estimate Uncertainty..........................................................................................113

6.5.2.3.1. Exposure Estimate Uncertainty: Results.........................................................113

6.5.2.3.2. Summary of Exposure Estimate Uncertainty..................................................118

6.5.3. Test Scenario 3: Mitigation Effectiveness.........................................................................................118

6.5.3.1. Mitigation Effectiveness Methods.....................................................................................118

6.5.3.1.1. Bootstrap Resampling.....................................................................................119

6.5.3.1.2. Detection Probability ......................................................................................120

6.5.3.2. Mitigation Effectiveness Results .......................................................................................121

6.5.3.3. Summary of Mitigation Effectiveness ...............................................................................129

6.5.4. Test Scenario 4: Effects of Aversion on Acoustic Exposure Estimates ............................................129

6.5.4.1. Effects of Aversion on Acoustic Exposure Estimates Methods.........................................130

6.5.4.2. Exposure History with Aversion........................................................................................130

6.5.4.3. Effects of Aversion on Acoustic Exposure Estimates: Results..........................................131

6.5.4.4. Summary of Effects of Aversion on Acoustic Exposure Estimates...................................138

6.5.5. Test Scenarios 5 and 6: Stand-off Distance and Simultaneous Firing...............................................139

6.5.5.1. Stand-off Distance .............................................................................................................139

6.5.5.2. Simultaneous Firing...........................................................................................................142

6.5.5.3. Summary of Stand-off Distance and Simultaneous Firing.................................................145

6.6. Cumulative and Chronic Effects Assessment Framework ............................................................................146

6.6.1. Overview ...........................................................................................................................................146

6.6.2. Method of Use...................................................................................................................................147
D-vi Acoustic Propagation and Marine Mammal Exposure Modeling

6.6.3. Calculator Output ..............................................................................................................................149

6.6.4. Discussion .........................................................................................................................................150

7. PHASE II: MARINE MAMMAL EXPOSURE ESTIMATES ................................................................151

7.1. Assumptions..................................................................................................................................................151

7.2. Phase II Modeling Methods ..........................................................................................................................153

7.2.1. Acoustic Source Parameters..............................................................................................................153

7.2.1.1. Airgun Array—8000 in3.....................................................................................................153

7.2.1.2. Single Airgun—90 in3........................................................................................................153

7.2.1.3. Boomer ..............................................................................................................................153

7.2.1.4. High Resolution Survey Sources .......................................................................................153

7.2.1.4.1. Multibeam Echosounder—Simrad EM2000...................................................154

7.2.1.4.2. Side-scan Sonar—EdgeTech 2200 IM............................................................154

7.2.1.4.3. Sub-bottom Profiler—EdgeTech 2200 IM with DW−424..............................154

7.2.2. Survey Patterns..................................................................................................................................154

7.2.2.1. 2-D Seismic Survey ...........................................................................................................155

7.2.2.2. 3-D Narrow Azimuth Seismic Survey ...............................................................................156

7.2.2.3. 3-D Wide Azimuth Seismic Survey...................................................................................156

7.2.2.4. Coil Seismic Survey...........................................................................................................157

7.2.2.5. High Resolution Geotechnical Survey...............................................................................158

7.2.3. Choice of Zone Boundaries...............................................................................................................158

7.2.3.1. Survey Extents...................................................................................................................159

7.2.3.2. Acoustic Modeling Sites....................................................................................................159

7.2.4. Environmental Parameters.................................................................................................................161

7.2.4.1. Bathymetry.........................................................................................................................161

7.2.4.2. Multi-Layer Geoacoustic Profile .......................................................................................161

7.2.4.3. Sound Speed Profiles.........................................................................................................163

7.2.4.3.1. Sound Speed Profiles for Box Centers............................................................165

7.2.4.3.2. Sound Speed Profiles for Acoustic Modeling Sites along Transects..............166

7.2.5. 3MB Simulation Areas......................................................................................................................169

7.2.5.1. Large Seismic Surveys.......................................................................................................169

7.2.5.2. High-resolution Surveys ....................................................................................................170

7.2.6. Animal Densities...............................................................................................................................171

7.2.6.1. Marine Mammal Density Estimates in Modeling Zones....................................................179

7.2.7. Animal Movement: JEMS.................................................................................................................179

7.2.7.1. Depth-restricted Density Adjustment.................................................................................179

7.2.7.2. Evaluation Time Period .....................................................................................................179

7.2.7.3. Annual Aggregate Estimates..............................................................................................180

7.3. Phase II Modeling Results.............................................................................................................................180

7.3.1. Acoustic Sources: Levels and Directivity..........................................................................................180

7.3.1.1. Airgun Sources ..................................................................................................................180

7.3.1.1.1. Airgun Array—8000 in3..................................................................................180

7.3.1.1.2. Single Airgun—90 in3.....................................................................................182

7.3.1.2. Boomer ..............................................................................................................................183

7.3.1.3. High-resolution Acoustic Sources .....................................................................................185

7.3.1.3.1. Multibeam Echosounder—Simrad EM2000...................................................185
Gulf of Mexico G&G Activities Programmatic EIS D-vii

7.3.1.3.2. Side-scan Sonar—EdgeTech 2200 IM............................................................185

7.3.1.3.3. Sub-bottom Profiler—EdgeTech 2200 IM, DW−424.....................................186

7.3.2. Per-Pulse Acoustic Field ...................................................................................................................187

7.3.2.1. Per-Pulse Acoustic Field for Input to JEMS......................................................................187

7.3.2.1.1. Seismic Survey (8000 in3 Airgun Array)........................................................187

7.3.2.1.2. Geotechnical Surveys with High-resolution sources ......................................188

7.3.2.2. Range to Zero-to-Peak SPL Isopleths................................................................................189

7.3.2.3. Per-Pulse Acoustic Field for Threshold Ranges ................................................................190

7.3.3. 24-hour Exposure Estimates..............................................................................................................190

7.3.4. Annual Exposure Estimates...............................................................................................................191

8. DISCUSSION ..............................................................................................................................201

9. LITERATURE CITED ...................................................................................................................204

APPENDIX A. PER-PULSE ACOUSTIC FIELD EXAMPLE RADII TABLES AND MAPS .........................220

APPENDIX B. TEST CASE SIMULATION RECEIVED LEVELS ...........................................................227

APPENDIX C. MARINE MAMMAL DISTRIBUTION IN THE GULF OF MEXICO ...................................233

APPENDIX D. 3MB ANIMAL MOVEMENT PARAMETERS ...............................................................251

APPENDIX E. PER-PULSE ACOUSTIC FIELD MAPS AND RADII .......................................................273

APPENDIX F. ANNUAL EXPOSURE ESTIMATES ..............................................................................286

Gulf of Mexico G&G Activities Programmatic EIS D-ix

Figures

Figure 1. Typical 3-D beam pattern for a circular transducer ............................................................... 21

Figure 2. Vertical cross section of a beam pattern measured in situ from a transducer ........................ 21

Figure 3. Calculated beam pattern for a circular transducer ................................................................. 22

Figure 4. Calculated beam pattern for a rectangular transducer ........................................................... 23

Figure 5. Calculated beam pattern for two rectangular transducers ...................................................... 23

Figure 6. The N×2-D and maximum-over-depth modeling approach. ................................................. 25

Figure 7. Cartoon animats in a moving sound field. ............................................................................. 28

Figure 8. Standard M-weighting functions for the four underwater functional marine mammal 

hearing groups ................................................................................................................................. 30

Figure 9. Frequency weighting functions for the cetacean functional hearing groups. ........................ 32

Figure 10. Locations of the Survey site A (purple box) and Survey site B (red box) and 

acoustic field modeling sites. ........................................................................................................... 37

Figure 11. Layout of the modeled airgun array .................................................................................... 39

Figure 12. Sound speed profiles ............................................................................................................ 43

Figure 13. Density estimates for sperm whales near Survey site A ...................................................... 44

Figure 14. Density estimates for sperm whales near Survey site B ...................................................... 45

Figure 15. The 8000 in3 array: .............................................................................................................. 46

Figure 16. Maximum directional source level (SL) in the horizontal plane ......................................... 47

Figure 17. Horizontal directivity of the 8000 in3 array. ........................................................................ 48

Figure 18. An example of per-pulse received SEL field ....................................................................... 49

Figure 19. Vessel track locations for behavioral response analysis at Survey sites A and B. .............. 51

Figure 20. Vessel track locations for injury analysis at Survey sites A and B. ..................................... 52

Figure 21. Bryde’s whales: Behavioral exposure estimates for (a) Survey sites A and (b) B. ............. 60

Figure 22. Common bottlenose dolphins: Behavioral exposure estimates for (a) Survey sites A 

and (b) B. ......................................................................................................................................... 61

Figure 23. Cuvier’s beaked whales: Behavioral exposure estimates for (a) Survey sites A and 

(b) B ................................................................................................................................................. 61

Figure 24. Short-finned pilot whales: Behavioral exposure estimates for (a) Survey sites A and 

(b) B ................................................................................................................................................. 62

Figure 25. Sperm whales: Behavioral exposure estimates for (a) Survey sites A and (b) B. ............... 62

Figure 26. Dwarf sperm whales: Behavioral exposure estimates for (a) Survey sites A and (b) B. ..... 63

Figure 27. Behavioral exposure estimates for (a) short-finned pilot whales and (b) sperm whales, 

both with reversed vessel tracks at Survey site A. ........................................................................... 63

Figure 28. Behavioral exposure estimates for (a) short-finned pilot whales and (b) sperm whales, 

with stationary source in deep water near Survey site B. ................................................................ 64

Figure 29. The Shelf zone (28.5° N, 90° W): Mean monthly sound speed profiles, separated into 

Seasons 1 (left) and 2 (right)............................................................................................................ 74

Figure 30. The Slope zone (27.25° N, 90° W): Mean monthly sound speed profiles, separated into 

Seasons 1 (left) and 2 (right)............................................................................................................ 75

Figure 31. Deep zone (25.5° N, 90° W): Mean monthly sound speed profiles. ................................... 75
D-x Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 32. Shelf zone: Modeled average and maximum-propagation sound speed profiles based on 

variations in CTD cast data for Seasons 1 (left) and 2 (right). ........................................................ 77

Figure 33. Slope zone: Modeled average and maximum-propagation sound profiles based on 

variations in CTD cast data for Seasons 1 (left) and 2 (right). ........................................................ 77

Figure 34. Deep zone: Modeled average and maximum-propagation sound speed profiles based 

on variations in CTD cast data. ........................................................................................................ 78

Figure 35. Shelf zone, Dec–Mar: Received SEL acoustic field using conservative (enhanced 

propagation) sound speed profile and median reflectivity geoacoustic parameters. ....................... 78

Figure 36. Shelf zone, Dec–Mar: Received SEL acoustic field using median sound speed profile 

and median reflectivity geoacoustic parameters. ............................................................................. 79

Figure 37. Shelf zone, Dec–Mar: Differential acoustic field due to variation in the sound speed 

profile. .............................................................................................................................................. 79

Figure 38. Shelf zone, Apr–Nov: Received SEL acoustic field using conservative sound 

(enhanced propagation) speed profile and median reflectivity geoacoustic parameters.................. 79

Figure 39. Shelf zone, Apr–Nov: Received SEL acoustic field using median sound speed profile

and median reflectivity geoacoustic parameters. ............................................................................ 80

Figure 40. Shelf zone, Apr–Nov: Differential acoustic field due to variation in the sound speed 

profile. .............................................................................................................................................. 80

Figure 41. Slope zone, Jul–Sep: Received SEL acoustic field using conservative sound speed 

profile and median reflectivity geoacoustic parameters. ................................................................. 80

Figure 42. Slope zone, Jul–Sep: Received SEL acoustic field using median sound speed profile 

and median reflectivity geoacoustic parameters. ............................................................................. 81

Figure 43. Slope zone, Jul–Sep: Differential acoustic field due to variation in the sound speed 

profile. .............................................................................................................................................. 81

Figure 44. Slope zone: Received SEL acoustic field sing conservative sound speed profile and 

median reflectivity geoacoustic parameters. .................................................................................... 81

Figure 45. Slope zone, Oct–Jun: Received SEL acoustic field using median sound speed profile 

and median reflectivity geoacoustic parameters. ............................................................................. 82

Figure 46. Slope zone, Oct–Jun: Differential acoustic field due to variation in the sound speed 

profile. .............................................................................................................................................. 82

Figure 47. Deep zone: Received SEL acoustic field using conservative sound speed profile and 

median reflectivity geoacoustic parameters. .................................................................................... 82

Figure 48. Deep zone: Received SEL acoustic field using median sound speed profile and median 

reflectivity geoacoustic parameters. ................................................................................................ 83

Figure 49. Deep zone: Differential acoustic field due to variation in the sound speed profile. ............ 83

Figure 50. The map of dominant type for the surficial sediments (NOS 2013) and location 

of the drill wells in the Gulf of Mexico. .......................................................................................... 84

Figure 51. Shelf zone, Dec–Mar: Received SEL acoustic field using median sound speed profile 

and high reflectivity geoacoustic parameters. .................................................................................. 86

Figure 52. Shelf zone, Dec–Mar: Received SEL acoustic field using median sound speed profile 

and median reflectivity geoacoustic parameters. ............................................................................. 86

Figure 53. Shelf zone, Dec–Mar: Differential acoustic field due to variation in the bottom 

geoacoustic parameters. ................................................................................................................... 87

Figure 54. Shelf zone, Apr–Nov: Received SEL acoustic field using median sound speed profile 

and high reflectivity geoacoustic parameters. .................................................................................. 87
Gulf of Mexico G&G Activities Programmatic EIS D-xi

Figure 55. Shelf zone, Apr–Nov: Received SEL acoustic field using median sound speed profile 

and median reflectivity geoacoustic parameters. ............................................................................. 87

Figure 56. Shelf zone, Apr–Nov: Differential acoustic field due to variation in the bottom 

geoacoustic parameters. ................................................................................................................... 88

Figure 57. Slope zone, Jul–Sep: Received SEL acoustic field using median sound speed profile 

and high reflectivity geoacoustic parameters. .................................................................................. 88

Figure 58. Slope zone, Jul–Sep: Received SEL acoustic field using median sound speed profile 

and median reflectivity geoacoustic parameters. ............................................................................. 88

Figure 59. Slope zone, Jul–Sep: Differential acoustic field due to variation in the bottom 

geoacoustic parameters. ................................................................................................................... 89

Figure 60. Slope zone, Oct–Jun: Received SEL acoustic field using median speed profile and 

high reflectivity geoacoustic parameters. ........................................................................................ 89

Figure 61. Slope zone, Oct–Jun: Received SEL acoustic field using median sound speed profile

and median reflectivity geoacoustic parameters. ............................................................................ 89

Figure 62. Slope zone, Oct–Jun: Differential acoustic field due to variation in the bottom 

geoacoustic parameters. ................................................................................................................... 90

Figure 63. Deep zone: Received SEL acoustic field using median sound speed profile and high 

reflectivity geoacoustic parameters. ................................................................................................ 90

Figure 64. Deep zone: Received SEL acoustic field using median sound speed profile and median 

reflectivity geoacoustic parameters. ................................................................................................ 90

Figure 65. Deep zone: Differential acoustic field due to variation in the bottom geoacoustic 

parameters. ....................................................................................................................................... 91

Figure 66. Shelf zone: The source when positioned at water column depth of 25 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 92

Figure 67. Shelf zone: The source when positioned at water column depth of 75 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 93

Figure 68. Shelf zone: The source when positioned at water column depth of 150 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 93

Figure 69. Shelf zone: Differential acoustic field for the source when positioned at water column 

depths of 25 and 75 m: Differential acoustic field due to variation of the water depth at the 

source. .............................................................................................................................................. 93

Figure 70. Shelf zone: Differential acoustic field for the source when positioned at water column 

depths of 75 and 150 m: Differential acoustic field due to variation of the water depth at the 

source. .............................................................................................................................................. 94

Figure 71. Slope zone: The source when positioned at water column depth of 300 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 94

Figure 72. Slope zone: The source when positioned at water column depth of 500 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 94

Figure 73. Slope zone: The source when positioned at water column depth of 750 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 95
D-xii Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 74. Slope zone: The source when positioned at water column depth of 1000 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 95

Figure 75. Slope zone: The source when positioned at water column depth of 1500 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 95

Figure 76. Slope zone: Differential acoustic field for the source when positioned at water column 

depths of 300 and 500 m. ................................................................................................................. 96

Figure 77. Slope zone: Differential acoustic field for the source when positioned at water column 

depths of 500 and 750 m. ................................................................................................................. 96

Figure 78. Slope zone: Differential acoustic field for the source when positioned at water column 

depths of 750 and 1000 m. ............................................................................................................... 96

Figure 79. Slope zone: Differential acoustic field for the source when positioned at water column 

depths of 1000 and 1500 m. ............................................................................................................. 97

Figure 80. Deep zone: The source when positioned at water column depth of 2000 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 97

Figure 81. Deep zone: The source when positioned at water column depth of 2500 m: Received 

SEL acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. ....................................................................................................................................... 97

Figure 82. Deep zone: Differential acoustic field for the source when positioned at water column 

depths of 2000 and 2500 m .............................................................................................................. 98

Figure 83. Bootstrap resampling and SEL injury and behavioral response exposure estimation 

for Bryde’s whales and dwarf sperm whales. ................................................................................ 105

Figure 84. Bootstrap resampled behavioral disruption exposure estimate distribution for 

modeled results and adjusted for real-world density estimate mean ± standard deviation at 

Survey site A.................................................................................................................................. 106

Figure 85. SEL Injury and behavioral disruption exposure estimate distributions for Bryde’s 

whales and dwarf sperm whales at Survey site A. ......................................................................... 111

Figure 86. Behavioral disruption exposure estimate distributions with social group size at 

Survey site A.................................................................................................................................. 112

Figure 87. Bootstrap resampling with acoustic uncertainty for SEL injury potential behavioral 

response for Bryde’s whales and dwarf sperm whales at Survey site A........................................ 115

Figure 88. Bootstrap resampling for SEL injury ................................................................................. 116

Figure 89. Potential behavioral response exposure estimates of species at Survey site A from 

bootstrap resampling ...................................................................................................................... 117

Figure 90. Cuvier’s beaked whales: Probability of exposure above injury thresholds at Survey 

site A without (left panels) and with mitigation (right panels) for peak SPL (top panels) and 

rms SPL (bottom panels). .............................................................................................................. 124

Figure 91. Common bottlenose dolphins: Probability of exposure at or above injury thresholds 

at Survey site A without (left panels) and with mitigation (right panels) for peak SPL (top 

panels) and rms SPL (bottom panels). ........................................................................................... 125

Figure 92. Short-finned pilot whales: Probability of exposure at or above injury thresholds at 

Survey site A without (left panels) and with mitigation (right panels) for peak SPL (top 

panels) and rms SPL (bottom panels). ........................................................................................... 126
Gulf of Mexico G&G Activities Programmatic EIS D-xiii

Figure 93. Sperm whales: Probability of exposure at or above injury thresholds at Survey site A 

without (left panels) and with mitigation (right panels) for peak SPL (top panels) and rms SPL 

(bottom panels). ............................................................................................................................. 127

Figure 94. Dwarf sperm whales: Probability of exposure at or above injury thresholds at Survey 

site A without (left panels) and with mitigation (right panels) for SEL (top panels), peak SPL 

(middle panels), and rms SPL (bottom panels). ............................................................................. 128

Figure 95. Probability of exposure at or above rms SPL injury thresholds for Bryde’s whales at 

Survey site A, (left) without and (right) with aversion. ................................................................. 132

Figure 96. Probability of exposure at or above peak SPL (top panels) and rms SPL (bottom 

panels) injury thresholds for Cuvier’s beaked whales at Survey site A, without (left panels) 

and with aversion (right panels)..................................................................................................... 133

Figure 97. Probability of exposure at or above peak SPL (top panels) and rms SPL (bottom 

panels) injury thresholds for common bottlenose dolphins at Survey site A, without (left 

panels) and with (right panels) aversion. ....................................................................................... 134

Figure 98. Probability of exposure at or above peak SPL (top panels) and rms SPL (bottom 

panels) injury thresholds for short-finned pilot whales at Survey site A, without (left panels) 

and with (right panels) aversion..................................................................................................... 135

Figure 99. Probability of exposure at or above peak SPL (top panels) and rms SPL (bottom 

panels) thresholds for sperm whales at Survey site A, without (left panels) and with (right 

panels) aversion. ............................................................................................................................ 136

Figure 100. Probability of exposure at or above (top panels) SEL, (middle panels) peak SPL, 

rms SPL (bottom panels) injury thresholds for dwarf sperm whales at Survey site A, without 

(left panels) and with (right panels) aversion. ............................................................................... 137

Figure 101. Waveforms predicted by FWRAM for the 8000 in3 array at Survey site A, for a 

10 m receiver depth. ...................................................................................................................... 141

Figure 102. Sound exposure level for four 8000 in3 arrays at the start of a 3-D wide azimuth 

seismic survey at Survey site A, S01 modeling province. ............................................................. 142

Figure 103. SPL for (top) one 8000 in3

 array and (bottom) two 8000 in3 arrays fired 

simultaneously with an across-track separation of 350 m and an along-track separation 

of 2700 m. ...................................................................................................................................... 144

Figure 104. Map automatically produced by the cumulative and chronic effects calculator, 

showing seismic survey positions and receiver locations. ............................................................. 148

Figure 105. Simulated portion of the track for the 2-D seismic survey. ............................................. 156

Figure 106. Simulated portion of the track for the 3-D NAZ seismic survey. .................................... 156

Figure 107. Simulated portion of the track for the 3-D WAZ seismic survey. ................................... 157

Figure 108. Simulated portion of the track for the Coil seismic survey. ............................................ 157

Figure 109. Simulated portion of the track for the geotechnical survey. ............................................ 158

Figure 110. Gulf of Mexico project area. ............................................................................................ 159

Figure 111. Sound speed profiles at the (left) Shelf, (center) Slope, and (right) Deep zones ............. 164

Figure 112. Sound speed profiles at modeling boxes, Season 1 ......................................................... 165

Figure 113. Sound speed profiles at modeling boxes, Season 3 ......................................................... 166

Figure 114. Sound speed profiles along the West transect ................................................................. 167

Figure 115. Sound speed profiles along Central transect .................................................................... 168

Figure 116. Sound speed profiles along East transect......................................................................... 169
D-xiv Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 117. Predicted (a) overpressure signature and (b) power spectrum in the broadside and 

endfire (horizontal) directions, for a generic 8000 in3

 airgun array towed at a depth of 8 m. ....... 181

Figure 118. Maximum 1/3-octave-band source level in the horizontal plane for a generic 

8000 in3 airgun array. ..................................................................................................................... 181

Figure 119. Directionality of predicted horizontal source levels for a generic 8000 in3

 airgun 

array. .............................................................................................................................................. 182

Figure 120. Predicted (a) overpressure signature and (b) power spectrum in the broadside and 

endfire (horizontal) directions for a single 90 in3

 airgun. .............................................................. 183

Figure 121. Maximum 1/3-octave-band source level in the horizontal plane for a single 90 in3 

airgun. ............................................................................................................................................ 183

Figure 122. Vertical beam pattern calculated for the Simrad EM2000 multibeam 88 × 17 width 

in the (left) along- and (right) across-track directions. .................................................................. 185

Figure 123. Vertical beam pattern calculated for the EdgeTech 2200 IM side-scan sonar 70 × 0.8 

width and 20 declination angle. Slices (left) at 20° declination angle and (right) across-track 

directions........................................................................................................................................ 186

Figure 124. Vertical beam pattern calculated for the EdgeTech 2200 IM sub-bottom with 20 

beamwidth...................................................................................................................................... 187

Figure 125. Probability density function of received levels shown as a histogram. ........................... 191

Figure 126. Broadband (10–5000 Hz) maximum-over-depth sound pressure levels for 8000 in3 

airgun array, in August at the Survey site A, S01 modeling province. .......................................... 224

Figure 127. Broadband (10–5000 Hz) maximum-over-depth sound pressure levels for 8000 in3 

airgun array, in August at the Survey site A, S02 modeling province. .......................................... 225

Figure 128. Broadband (10–5000 Hz) maximum-over-depth sound pressure levels for 8000 in3 

airgun array, in August at the Survey site B, D01 modeling province. ......................................... 226
Gulf of Mexico G&G Activities Programmatic EIS D-xv

Tables 

Table 1. Marine mammal functional hearing groups ............................................................................ 11

Table 2. Marine mammal species considered in the acoustic exposure analysis. ................................. 18

Table 3. Low and high frequency cut-off parameters of M-weighting functions for the cetacean 

functional hearing groups ................................................................................................................ 30

Table 4. Frequency weighting parameters for the cetacean functional hearing groups ........................ 31

Table 5. Injury exposure criteria for pulsed sounds. ............................................................................. 34

Table 6. Behavioral exposure criteria. .................................................................................................. 34

Table 7. Relative airgun positions within each of the six sub-arrays. ................................................... 38

Table 8. Geoacoustic properties of the sub-bottom sediments as a function of depth for the S01 

modeling province. .......................................................................................................................... 41

Table 9. Geoacoustic properties of the sub-bottom sediments as a function of depth for the S02 

modeling province. .......................................................................................................................... 41

Table 10. Geoacoustic properties of the sub-bottom sediments as a function of depth for the D01 

modeling province. .......................................................................................................................... 42

Table 11. Summer regional statistics of marine mammal density near Survey site A .......................... 45

Table 12. Summer regional statistics of marine mammal density near Survey site B .......................... 45

Table 13. Horizontal source level specifications (10–5000 Hz) for the seismic airgun array .............. 47

Table 14. Number of modeled cetaceans above exposure criteria for Survey site A for entire 

duration of the simulations. ............................................................................................................. 53

Table 15. Number of modeled cetaceans above exposure criteria for Survey site B for entire 

duration of the simulations. ............................................................................................................. 53

Table 16. Real-world number of cetaceans above injury exposure criteria for summer for Survey 

site A. ............................................................................................................................................... 54

Table 17. Real-world number of cetaceans above injury exposure criteria for summer for Survey 

site B. ............................................................................................................................................... 54

Table 18. Real-world number of cetaceans above behavioral exposure criteria for summer for 

Survey site A.................................................................................................................................... 54

Table 19. Real-world number of cetaceans above behavioral exposure criteria for summer for 

Survey site B. ................................................................................................................................... 55

Table 20. Average number of modeled cetaceans above exposure criteria at Survey site A for 

24 h sliding windows. ...................................................................................................................... 65

Table 21. Average number of modeled cetaceans above exposure criteria at Survey site B for 

24 h sliding windows. ...................................................................................................................... 66

Table 22. Number of modeled cetaceans above exposure criteria at Survey site A for average 

24 h sliding windows estimate scaled to full duration (5 or 30 days). ............................................. 66

Table 23. Number of modeled cetacean animats above exposure criteria at Survey site B for 

average 24 h sliding windows estimate scaled to full duration (5 or 30 days). ............................... 66

Table 24. Percentage difference in number of modeled cetaceans above exposure criteria at 

Survey site A for 24 h sliding windows scaled to 4 day evaluation window. ................................. 67

Table 25. Percentage difference in number of modeled cetaceans above exposure criteria at 

Survey site B for 24 h sliding windows scaled to 4 day evaluation window. .................................. 67
D-xvi Acoustic Propagation and Marine Mammal Exposure Modeling

Table 26. Amount of time that animats exceed NMFS threshold criteria at Survey site A for 

30 days and 24 h. ............................................................................................................................. 67

Table 27. Amount of time that animats exceed NMFS threshold criteria at Survey site B for 

30 days and 24 h. ............................................................................................................................. 68

Table 28. Depth zones along the study line. ......................................................................................... 73

Table 29. Modeled seasons and their characteristics. ........................................................................... 73

Table 30. Acoustic field differences between maximum-propagation and average sound speed 

profile conditions. ............................................................................................................................ 84

Table 31. Shelf zone: Median and higher reflectivity geoacoustic profiles. ......................................... 85

Table 32. Slope zone: Lower, median, and higher reflectivity geoacoustic profiles. ........................... 85

Table 33. Deep zone: Lower, median, and higher reflectivity geoacoustic profiles. ............................ 86

Table 34. Acoustic field differences between reflective and average geoacoustic conditions. ............ 91

Table 35. Acoustic field uncertainty due to variations in the water depth at the source. ...................... 99

Table 36. Real-world density estimates for summer at Survey sites A and B. ................................... 103

Table 37. Published (social) group size statistics for Test Case species. ............................................ 108

Table 38. Social group size (number of individuals ± standard deviation) used to evaluate 

effects on exposure estimates. ....................................................................................................... 110

Table 39. Estimates of trackline detection probability, g(0), coefficients of variation (CV) 

for g(0), and mean group size. ....................................................................................................... 120

Table 40. Cuvier’s beaked whales: Modeled Level A exposure estimates and mitigation 

efficiency for peak SPL and rms SPL. ........................................................................................... 121

Table 41. Common bottlenose dolphins: Modeled Level A exposure estimates and mitigation 

efficiency for peak SPL and rms SPL. ........................................................................................... 122

Table 42. Short-finned pilot whales: Modeled Level A exposure estimates and mitigation 

efficiency for peak SPL and rms SPL. ........................................................................................... 122

Table 43. Sperm whales: Modeled Level A exposure estimates and mitigation efficiency for 

peak SPL and rms SPL. ................................................................................................................. 123

Table 44. Dwarf-sperm whales: Modeled Level A exposure estimates and mitigation efficiency 

for 5-day SEL, peak SPL, and rms SPL. ....................................................................................... 123

Table 45. Modeled Level A exposures, with and without aversion. ................................................... 132

Table 46. Receiver site locations and water depths. ........................................................................... 146

Table 47. Summary of the Phase II surveys considered to determine the exposure estimates. .......... 155

Table 48. Modeling sites along the West transect. ............................................................................. 160

Table 49. Modeling sites along Central transect. ................................................................................ 160

Table 50. Modeling sites along East transect. ..................................................................................... 161

Table 51. Center coordinates of survey boxes. ................................................................................... 161

Table 52. Shelf zone Center and West: Geoacoustic properties of the sub-bottom sediments ........... 162

Table 53. Shelf zone East: Geoacoustic properties of the sub-bottom sediments ............................... 162

Table 54. Slope zone: Geoacoustic properties of the sub-bottom sediments ...................................... 163

Table 55. Deep zone: Geoacoustic properties of the sub-bottom sediments ...................................... 163

Table 56. Representative months for each season and modeling zone. .............................................. 164

Table 57. Modeling seasons for each box. .......................................................................................... 165

Table 58. Modeling seasons for the sites along transects. .................................................................. 166
Gulf of Mexico G&G Activities Programmatic EIS D-xvii

Table 59. Geographic extent of the animat movement boxes for behavior simulation with the 

large seismic surveys. .................................................................................................................... 170

Table 60. Geographic extent of the animat movement boxes for injury simulation with the large 

seismic surveys. ............................................................................................................................. 170

Table 61. Geographic extent of the animat movement boxes for both behavior and injury 

simulation with the high-resolution surveys. ................................................................................. 171

Table 62. Zone 1 Marine mammal density estimates. ........................................................................ 172

Table 63. Zone 2 Marine mammal density estimates. ........................................................................ 173

Table 64. Zone 3 Marine mammal density estimates. ........................................................................ 174

Table 65. Zone 4 Marine mammal density estimates. ........................................................................ 175

Table 66. Zone 5 Marine mammal density estimates. ........................................................................ 176

Table 67. Zone 6 Marine mammal density estimates. ........................................................................ 177

Table 68. Zone 7 Marine mammal density estimates. ........................................................................ 178

Table 69. Horizontal source level specifications for a generic 8000 in3 airgun array. ....................... 181

Table 70. Estimated source levels (SELs) and beamwidths from the AA301 boomer plate .............. 184

Table 71. Boomer and 90 in3 airgun broadband source levels after M-weighting filters were applied.185

Table 72. Modeling parameters for the geotechnical sources. ............................................................ 189

Table 73. Angle step configuration of profiles around side-scan sonar. ............................................. 189

Table 74. Ranges to specific threshold levels for all sources.............................................................. 190

Table 75. Projected level of effort in days (24 h) for survey types in years 2016 to 2025. ................ 192

Table 76. Decade exposure estimates totals for 2-D survey (8000 in3 airgun array, 1 vessel). ......... 194

Table 77. Decade exposure estimates totals for 3-D NAZ survey (8000 in3

 airgun array, 

2 vessels). ....................................................................................................................................... 195

Table 78. Decade exposure estimates totals for 3-D WAZ survey (8000 in3

 airgun array, 

4 vessels). ....................................................................................................................................... 196

Table 79. Decade exposure estimates totals for Coil survey (8000 in3 airgun array, 4 vessels). ........ 197

Table 80. Decade exposure estimates totals for 90 in3

 airgun. ........................................................... 198

Table 81. Decade exposure estimates totals for boomer. .................................................................... 199

Table 82. Decade exposure estimate totals for the high resolution sources (side-scan sonar, 

sub-bottom profiler, and multibeam scanner). ............................................................................... 200

Table 83. 8000 in3 airgun array at the Survey site A, S01 modeling province: maximum 

(Rmax, m) and 95% (R95%, m) horizontal distance .......................................................................... 221

Table 84. 8000 in3 airgun array at the Survey site A, S02 modeling province: maximum 

(Rmax, m) and 95% (R95%, m) horizontal distance .......................................................................... 222

Table 85. 8000 in3 airgun array at the Survey site B, D01 modeling province: maximum 

(Rmax, m) and 95% (R95%, m) horizontal distance .......................................................................... 223

Gulf of Mexico G&G Activities Programmatic EIS D-1 

1. Executive Summary 

1.1. Overview

This report provides estimates of the annual marine mammal acoustic exposure caused by sounds from 

geological and geophysical exploration activity in the Gulf of Mexico for years 2016 to 2025. Exposure 

estimates were computed from modeled sound levels as received by simulated animals (animats) in the 

area for several exploration survey types performed at multiple locations. Because animals and noise 

sources move relative to the environment and each other, and the sound fields generated by the sound 

sources are shaped by various physical parameters, the sound levels received by an animal are a complex 

function of location and time. We used acoustic modeling to compute three-dimensional (3-D) sound 

fields that varied with time, and we simulated realistic movements of animats within these fields to 

sample the sound levels in a manner representing how real animals would experience this sound. From 

the time history of the received sound levels, the number of animats exposed to levels exceeding 

threshold criteria were determined and then adjusted by the number of animals in the area to estimate the 

potential number of animals impacted. 

The project was divided into two phases. In Phase I, a typical wide azimuth geophysical survey using an 

airgun array source was simulated at two locations within the Mississippi Canyon. This was done to 

establish the basic methodological approach and to evaluate the sensitivities of results to uncertainties in 

input parameters. Results from the Test Scenarios were then used to guide the main modeling effort of 

Phase II. In Phase II, we divided the Gulf into seven modeling zones and simulated six survey types 

within each zone to estimate the potential effects of each survey. The results from each zone were 

summed to provide Gulf-wide estimates of effects on each marine mammal species for each survey type 

for each year based on specific assumed levels of survey activities. 

1.2. Sounds and Marine Mammals

The Marine Mammal Protection Act defines harassment as activities that can potentially injure marine 

mammals or disrupt their behavioral patterns (MMPA 2007); loud sounds produced by geophysical 

survey equipment are possible sources of such harassment. National Marine Fisheries Service (NMFS) 

adopted threshold criteria thought to represent cautionary lower limits for pulsed sound levels that could 

injure marine mammals or disrupt their activities. The thresholds for cetaceans exposed to impulsive 

noise were set at 180 dB re 1 μPa rms sound pressure level (rms SPL) for potential injury (Level A 

harassment) and 160 dB re 1 μPa rms SPL for potential behavioral disruption (Level B harassment; 

NFMS 1995, NMFS 2000). Animals exceeding these thresholds were considered exposed at their 

respective harassment level. As further knowledge on injury from sound became available, an expert 

group reviewed the available evidence and published suggestions for marine mammal sound exposure 

criteria (Southall et al. 2007). The present study has considered, in the exposure estimates, the NMFS 

criteria and adaptations of the Southall et al. (2007) criteria based on additional studies.

Injury to marine mammals’ anatomical, morphological, and physiological hearing structures (hereafter 

called hearing structures) can be caused by the fatiguing effect of accumulated sound energy. This energy, 

measured in terms of the sound exposure level (SEL) 1

, depends on the position of the animal in the sound 

 

1 Sound Exposure Level (SEL) is numerically proportional to acoustic energy flux density only when the 

acoustic impedance is constant and purely resistive. That is not the case when surface or seabed 

reflections are present or in refractive environments. SEL is not expressed in energy density units.
D-2 Acoustic Propagation and Marine Mammal Exposure Modeling

field. It changes as the animal and the sound source move, and continues to accumulate as long as the 

animal is exposed to the sound. Because intense sounds of short duration can also damage an animal’s 

hearing structures, an additional metric of peak sound pressure level (peak SPL) is also used to assess 

acoustic exposure risk. The exposure duration is not a factor in determining potential injury due to peak 

SPL; only the proximity of an animal to a source is relevant for estimating this metric. 

Defining sound levels that disrupt behavioral patterns is difficult because responses depend on the context 

in which the animal receives the sound. The environmental context and responses depend on many 

factors, including an animal’s behavioral mode when it hears sounds (e.g., feeding, resting, or migrating), 

and on biological factors (e.g., age and sex). Available data are consistent with the notion that louder 

sounds evoke greater responses, but the levels at which responses occur are not necessarily consistent. To 

predict the probability of behavioral response, we used a step function based on the received rms SPL. 

Some species, beaked whales in particular, are known to be more behaviorally sensitive to sounds than 

other species, so the function was adjusted as warranted for such species. To evaluate the potential for 

behavioral disruption, the maximum sound pressure level each simulated animal received was identified 

and the step function used to determine the number of simulated animals with the potential to respond. 

In developing the exposure effects criteria, a 24 h reset period was chosen. A 24 h reset period is 

commonly used and means that acoustic energy accumulation and the maximum values of the other 

metrics were reset after 24 h. Individual animats were eligible to be re-exposed in subsequent 24 h 

periods. 

The NMFS exposure criteria for injury (180 dB re 1 μPa rms SPL) and behavioral disruption (160 dB re 

1 μPa rms SPL) uses unfiltered (unweighted) sound fields when determining the number of animals 

exposed to levels exceeding threshold. The Southall et al. (2007) criteria attempt to account for the 

hearing ability of the animals. Southall et al. (2007) propose weighting functions for species groups based 

on their hearing range. These M-weighting filters, based on known and assumed species hearing ranges 

(audiograms) divide the cetaceans into three hearing groups low-, mid-, and high- frequency specialists 

(Southall et al. 2007) . Later, Finneran and Jenkins (2012) developed a weighting function based on 

perceptual measure of subjective loudness. Equal-loudness contours better match the onset of hearing 

impairment (temporary threshold shift) than the original M-weighting functions. Data for the equalloudness contours do not, however, cover the full frequency range of the M-weighting filters. Finneran 

and Jenkins (2012) propose a hybrid filter based on the equal-loudness contours in their measured 

frequency band and, outside of this range, the original M-weighting function was discounted to match the 

end points of the equal-loudness functions. Finneran and Jenkins (2012) term the hybrid filters Type II Mweighting to distinguish them from the original M-weighting, which they term Type I M-weighting.

Because Type II filtering was designed to better-predict the onset of injury, it is used in the current report 

to evaluate exposure for potential injury when using the SEL metric for mid- and high-frequency species. 

For low-frequency species, Type I filtering is used. No filtering is used when evaluating potential injury 

with the peak SPL metric. Although the Type II filtering is based on perceptual measures and, therefore, 

could be an appropriate indicator of behavioral response, as a conservative measure, Type I filtering is

used to evaluate potential behavioral disruption using rms SPL criteria with a step function. The current 

report uses the step function from Wood et al. (2012), which sets out a graded step of increasing 

probability of behavioral response with increasing received level. Additionally, following Wood et al. 

(2012), the step function is modified for behaviorally sensitive species (beaked whales). 

1.3. Acoustic Modeling

Acoustic source emission levels of a single airgun and an airgun array are calculated using the Airgun 

Array Source Model (AASM; JASCO Applied Sciences). Source levels of high-resolution survey sources 

are obtained from manufacturer’s specifications for representative sources. Acoustic transmission loss as 
Gulf of Mexico G&G Activities Programmatic EIS D-3 

a function of range from each source is calculated using the Marine Operations Noise Model (MONM; 

JASCO Applied Sciences) for multiple propagation radials centered at the source to yield 3-D 

transmission loss fields in the surrounding area. The primary seasonal influence on transmission loss is 

the presence of a sound channel, or duct, near the surface in winter. To account for seasonal variability in 

propagation, winter (most conservative) and summer (least conservative) were modeled. The modeled 

sound fields were also filtered for the hearing ability of the animals as described above. 

To account for both the geospatial dependence of acoustic fields and the geographic variations of animal 

distributions, the project area of the Gulf was divided into seven zones. The selected zone boundaries, 

patterned to conform to BOEM’s planning areas where possible, also considered sound propagation 

conditions and species distribution to create regions of optimized uniformity in both acoustic environment 

and animal density. This approach allows the calculation of generalized sound exposure estimates for 

each species for a representative survey type, season, and zone in which the survey occurs. Modeling was 

performed for each of the six different acoustic survey types that are assessed in this study: 2-D, 3-D 

narrow azimuth (NAZ), 3-D wide-azimuth (WAZ), Coil, Shallow Hazard (using a single airgun or 

boomer), and high resolution surveys (using side-scan sonar, sub-bottom profiler, and multibeam 

echosounder). The 2-D, 3-D NAZ, 3-D WAZ, and Coil represent large seismic exploration surveys using 

8000 in3 towed airgun array(s) as the sound source(s). 

1.4. Marine Mammals in the Gulf of Mexico

Twenty-one cetacean species have been sighted in surveys since 1991 (Waring et al. 2013). Eighteen are 

mid-frequency hearing specialists—Atlantic spotted dolphins (Stenella frontalis), beaked whales spp. 

(Cuvier’s (Ziphius cavirostris), Blainville’s (Mesoplodon densirostris), Gervais’ (Mesoplodon 

europaeus)), common bottlenose dolphins (Tursiops truncatus), clymene dolphins (Stenella clymene), 

false killer whales (Pseudorca crassidens), Fraser’s dolphins (Lagenodelphis hosei), killer whales

(Orcinus orca), melon-headed whales (Peponocephala electra), pantropical spotted dolphins (Stenella

attenuata), pygmy killer whales (Feresa attenuata), Risso’s dolphins (Grampus griseus), rough-toothed 

dolphins (Steno bredanesis), short-finned pilot whales (Globicephala melas), sperm whales (Physeter 

macrocephalus), spinner dolphins (Stenella longirostris), and striped dolphins (Stenella coeruleoalba). 

Bryde’s whales (Balaenoptera brydei/edeni) are the only low-frequency species, and dwarf and pygmy 

sperm whales (Kogia sima, Kogia breviceps) comprise the only high-frequency hearing specialist group. 

In Phase I, the Navy’s U.S. Navy OPAREA Density Estimate (NODE; DoN 2007) model was used to 

obtain animal density estimates (animals/km2

). In Phase II, more current density estimates were obtained 

from the Marine Geospatial Ecology Laboratory at Duke University preliminary results (Roberts et al., in 

preparation). In part, distribution information was used to inform boundary choices when establishing 

modeling zones. Density information was obtained for each of the zones and used when determining 

exposure estimates. 

1.5. Animal Movement Modeling

This analysis uses the Marine Mammal Movement and Behavior (3MB) model developed by Houser 

(2006). Parameter values to control animat movement are determined using behavioral observations of the 

species members and reviewing behavior reported by tagging studies. The amount and quality of data 

varies by species, but often provides a detailed description of the proximate behavior expected for real 

individual animals. Because there are few or no data available for some species included in this study, 

surrogate species with more available information are used: Pantropical spotted dolphins are used as a 

surrogate for Clymene, spinner, and striped dolphins; short-finned pilot whales are surrogates for Fraser’s 

dolphins, the Kogia species, and melon-headed whales; and rough-toothed dolphins are surrogates for 
D-4 Acoustic Propagation and Marine Mammal Exposure Modeling

false killer whales and pygmy killer whales. Observational data for all remaining species in the study 

were sufficient to determine animat movement. The use of surrogate species is a reasonable assumption 

for the simulation of proximate or observable behavior, and it is unlikely that this choice adds more 

uncertainty about location preference.

1.6. Phase I

A Test Case simulating a typical WAZ survey at two locations was performed as a demonstration of the 

basic modeling approach and as an investigation tool to establish methods used in the full modeling 

approach of Phase II. Test Scenarios were undertaken using, primarily, the results of the Test Case to 

investigate the effects of methodological choices on exposure estimates. Surveys vary in duration and 

some can be months long. In Test Scenario 1, a method for scaling up simulation results to account for 

long-duration surveys was suggested. In Test Scenario 2, sources of uncertainty and their effects on 

exposures estimates were investigated. In general, the finding of Test Scenario 2 was that uncertainty 

affects the distribution of the number of animals projected to exceed threshold levels, but the mean 

number remains the same. Test Scenario 3 found that mitigation procedures involving shut-downs for 

animals observed within an exclusion zone may reduce the number of animals exposed, but the 

effectiveness depends on the probability of detecting animals near the source. Detection probability varies 

with species and weather. Similarly, in Test Scenario 4, it was shown that animals avoiding high sound 

levels (aversion) potentially reduces the number of animals exposed to levels exceeding a threshold, but 

there is little information available upon which to define such behavior. Mitigation and aversion were not 

suggested for use in the Phase II modeling. Test Scenarios 5 and 6 investigated the effects of overlapping 

surveys and the impact of simultaneous firing. In neither case were these occurrences found to have a 

practical impact on exposure estimates. In other words, the exposure estimates from closely-spaced 

surveys analyzed separately and summed were as high as or higher than if the two surveys were evaluated 

as a single, combined survey.

1.7. Phase II: Annual Acoustic Exposure Estimates

The top-level results of the Phase II analysis are estimates of the number of exposures for each species 

and each year from 2016 to 2025 for the entire Gulf of Mexico. To get these annual aggregate exposure 

estimates, 24 h average exposure estimates from each survey type were scaled by the number of expected 

survey days from BOEM’s regulatory planning projections. Because these projections are not seasonspecific, surveys are assumed to be equally likely to occur at any time of the year and at any location 

within a given zone. The exposure estimates from the zones are summed to provide an annual exposure 

estimate for each species for the entire Gulf. 
Gulf of Mexico G&G Activities Programmatic EIS D-5 

2. Project Overview

The overall goal of this project is to estimate the yearly acoustic exposures received by marine mammals 

due to geological and geophysical survey activities in the Gulf of Mexico for the coming decade. This 

information will be used in developing a Programmatic Environmental Impact Statement, pursuant to the 

Marine Mammal Protection Act petition for rule making and the consultation under Section 7 of the 

Endangered Species Act. Six different seismic survey types will be assessed: 2-D, 3-D narrow azimuth 

(NAZ), 3-D wide azimuth (WAZ), Coil, Shallow Hazard (using single airgun or boomer), and high 

resolution (using side-scan sonar, sub-bottom profiler, and multibeam echosounder). The exact number, 

type, and location of future surveys are not known, but yearly level-of-effort projections are available.

The project was divided into two phases. In Phase I, a typical WAZ survey was simulated at two 

locations. This was done to establish the basic methodological approach and the results used to evaluate 

scenarios that may influence exposure estimates. Results from the Test Scenarios were then used to guide 

the main modeling effort of Phase II. In Phase II, we divided the Gulf into modeling zones and simulated 

each survey type in each zone to estimate the potential effects of each survey. The results from each zone 

were summed to provide Gulf-wide estimates of effects on each marine mammal species for each survey 

type for each year.

A modeling workshop was held in January 2014 (in Silver Spring, MD) as a collaborative effort between 

the American Petroleum Institute (API) and the International Association of Geophysical Contractors 

(IAGC), the National Marine Fisheries Service (NMFS), and Bureau of Ocean Energy Management 

(BOEM). The objectives of the workshop were to identify 1) gaps in modeling sound fields from airgun 

arrays and other active acoustic sources, including data requirements and performance in various 

contexts, 2) gaps in approaches to integration of modeled sound fields with biological data to estimate 

marine mammal exposures, and 3) assumptions and uncertainties in approaches and resultant effects on 

exposure estimates. This workshop aided BOEM and NOAA’s development of the Request for Proposals, 

Statement of Work, and by extension the methodologies undertaken in this modeling project. 
D-6 Acoustic Propagation and Marine Mammal Exposure Modeling

3. Introduction

3.1. The Ocean Soundscape

Human-generated (anthropogenic) contributions to the ocean’s soundscape have steadily increased in the 

past several decades largely driven by a worldwide increase in oil and gas exploration and in shipping 

(Hildebrand 2009). Some anthropogenic sources, such as vessel noise, are a chronic contribution to local 

and global soundscapes. Other anthropogenic sources affect marine life on a more restricted temporal and 

spatial scale, but often produce high sound energies and may pose immediate health risks to marine 

wildlife. Many anthropogenic sounds are produced intentionally as part of active data gathering effort 

using sonar, depth sounding, and seismic surveys. When seismic surveys expanded into deep water, their 

sound footprints increased markedly and these signals are detectable across ocean basins (Nieukirk et al. 

2004). 

3.1.1. Seismic Sources

3.1.1.1. Airguns

Seismic airguns generate pulsed acoustic energy by releasing into the water highly compressed air, which 

forms air bubbles that undergo a damped volume oscillation and emit an acoustic pressure wave that 

follows the bubble’s oscillating internal pressure. Seismic airguns produce sounds primarily at 

frequencies from a few hertz to a few kilohertz, but also produce lower level sounds at higher frequencies. 

Larger airguns, with larger internal air volume, produce higher broadband sound levels with sound energy 

spectrum shifted toward the lower frequencies. Single airguns or multiple airguns arranged in a spatial 

pattern (referred to as an airgun array) are typically towed by a survey vessel, with shots or impulses 

typically generated every 5 to 30 s along survey track lines. 

A single airgun produces an approximately omnidirectional sound field—the acoustic energy is initially

emitted equally in all directions. The sound signal that reflects from the water’s surface, however, 

interacts with sounds that travel directly from the airgun. The result of this interaction is that, on average, 

more sound energy is focused downwardly than horizontally, an effect that is more prominent for lower 

frequencies. Larger 2-D and 3-D seismic surveys usually use multiple airguns arranged in arrays; this 

configuration emits higher overall sound levels, specifically more highly downward directed. The arrays 

are configured with most of the airguns in a horizontal plane. This configuration, combined with the 

effect of the surface reflection, focuses more sound energy downwardly, while emitting lower levels of 

sound horizontally. Airgun arrays generally show significant horizontal directionality patterns due to the 

phase delay between pulses from horizontally separated lines of airguns. 

3.1.2. High-resolution Sources

3.1.2.1. Side-scan Sonar Systems

Side-scan sonar systems produce shaded relief images of the ocean bottom by recording the intensity and 

timing of signals reflected off the seafloor. Side-scan sonars consist of two transducers on the sides of the 

sonar body that are oriented orthogonally to the towing direction. The projected acoustic beams are 

usually wide in the vertical plane (50°−70°) and very narrow in the horizontal plane (less than a few 

degrees). The declination of the beam axis is small: 10°−20° below the horizon. Side-scan sonars can be 
Gulf of Mexico G&G Activities Programmatic EIS D-7 

mounted on a survey vessel, towed behind it, or be part of a survey complex installed on an autonomous 

underwater vehicle (AUV).

3.1.2.2. Multibeam Echosounders Sonar Systems

Multibeam echosounder sonar systems use an array of transducers that project a fan-shaped beam under 

the hull of a survey ship and orthogonal to the direction of motion. The system measures the time for the 

acoustic signal to travel to the ocean floor and back to the receiver. The multibeam echosounder produces 

a swath of depth measurements to ensure full coverage of an area. The coverage area on the seafloor is 

typically two to four times the water depth. Many multibeam echosounder systems can record acoustic 

backscatter data. Multibeam backscatter is intensity data that, when processed, creates a low-resolution 

image which often helps interpret and post-process the bathymetric data. Instead of deploying the 

multibeam echosounder under the hull of the survey ship, it can alternatively be deployed on an AUV. 

3.1.2.3. Sub-bottom Profiler Sonar Systems

Sub-bottom profiler sonar systems are used to generate vertical cross-section plots of the layers of 

sediment under the ocean floor. To make measurements, the sub-bottom profiler is towed behind a survey 

vessel or deployed on an AUV. The towed body of the sub-bottom profiles system contains the acoustic 

source and receiver elements. The source transducer projects a chirp pulse that spans an operatorselectable frequency band. The lower and upper limits of the sonar’s frequency band are usually between 

~ 1 to 20 kHz. The system projects a single beam directed vertically down. The projected beamwidth 

depends on the operating frequency, but is approximately 10°−30°. 

3.1.2.4. Boomer Sources

Some sub-bottom profiler systems use a boomer source, which consists of an insulated metal plate paired 

with an adjacent electromagnetic Coil. A powerful electrical discharge pulse generated by a shipboard 

power supply and capacitor bank is applied to the Coil, generating an abrupt and strong magnetic field 

that repels the metal plate. The resulting mechanical impulse generates a high-amplitude broadband 

acoustic pulse in the water, with high downward directivity (Verbeek and McGee 1995). The boomer 

source functions as a circular piston surrounded by a rigid baffle; it is not a point-like source (Verbeek 

and McGee 1995) because the beam pattern of a boomer plate shows some directivity for frequencies 

above 1 kHz, where acoustic wavelength is on the same order of magnitude as the baffle size.

3.1.3. Pulsed Versus Non-Pulsed Sounds

Anthropogenic sounds can affect marine life in a variety of ways. Numerous scientific reviews and 

workshops over the past 40 years have investigated these effects (Payne and Webb 1971, Fletcher and 

Busnel 1978, Richardson et al. 1995, MMC 2007, Nowacek et al. 2007, Southall et al. 2007, Weilgart 

2007, Tyack 2008). Anthropogenic sounds that could affect marine life are generally divided into two 

main categories when they are investigated—pulsed divided into single and multiple, and non-pulsed 

sounds (Southall et al. 2007). Pulsed or impulsive sounds include pile driving and airgun shots as well as 

some sonar; non-pulsed, continuous-types of sounds include certain sonar and vessel propulsion sounds 

and machinery sounds. Numerous definitions and mathematical distinctions distinguish pulsed from nonpulsed sounds (Burdic 2003). Southall et al. (2007) adopted a measurement-based distinction originally 

proposed by Harris (1998) that if measurements between the continuous and impulse sound level meter 

settings differ by ≥ 3 dB, a sound is pulsed, whereas if the difference is < 3 dB the sound is non-pulsed. 

The distinction between these two sound types, however, is not always obvious. Certain signals, for 

example those from acoustic deterrent or harassment devices, share properties of both pulsed and non-
D-8 Acoustic Propagation and Marine Mammal Exposure Modeling

pulsed sounds. A signal near a source could be categorized as a pulse, but due to propagation effects as it 

moves farther from the source, it could be categorized as non-pulsed (e.g., Greene and Richardson 1988). 

3.2. Acoustic Metrics

Underwater sound pressure amplitude is commonly measured in decibels (dB) relative to a fixed 

reference pressure of pο = 1 μPa. Because the loudness and other exposureeffects of impulsive (pulsed) 

noise, e.g., shots from seismic airguns, are not generally proportional to the instantaneous acoustic 

pressure, several sound level metrics are commonly used to evaluate impulsive sound effects on marine 

life. 

The zero-to-peak sound pressure level (SPL), or peak SPL (Lpk, dB re 1 μPa), is the maximum 

instantaneous sound pressure level in a stated frequency band attained by an impulse, p(t): 

( )

















=

ο

2

2

pk 10

max )( lοg10

p

tp L (1) 

The peak-to-peak SPL (Lpk-pk, dB re 1 μPa) is the difference between the maximum and minimum 

instantaneous sound pressure level in a stated frequency band attained by an impulse, p(t): 

[ ( ) ( )]











 − =

ο

− 2

2

pkpk 10

max )( min )( lοg10

p

tptp L (2) 

The root-mean square (rms) SPL (Lp, dB re 1 μPa) is the rms pressure level in a stated frequency band 

over a time window (T, s) containing the pulse: 















 = ∫ ο

2 2

10 )( 1 lοg10 pdttp T

L

T

p (3) 

The rms SPL can be thought of as a measure related to the average sound intensity or as the effective 

pressure intensity over the duration of an acoustic event, such as the emission of one acoustic pulse. 

Because the time window length, T, is a divisor, pulses having the same total acoustic energy, but more 

spread out in time, will have a lower rms SPL. The value of T for the purpose of the rms SPL calculation 

can be selected using different approaches. According to one, T is defined as the 90% energy pulse 

duration, containing the central 90% (from 5% to 95% of the total) of the cumulative square pressure (or 

sound exposure level) of the pulse, rather than over a fixed time window (Malme et al. 1986, Greene 

1997, McCauley et al. 1998). The 90% rms SPL (Lp90, dB re 1 μPa) in a stated frequency band is 

calculated over this 90% energy time window, T90: 















 = ∫ ο

2 2

90

90 10

90

)( 1 10lοg pdttp TL

T

p (4) 

The other approach for rms SPL calculation of a pulse is to use fixed time window. In this case, a sliding 

window was used to calculate rms SPL values for a series of fixed window lengths within the pulse. The 

maximum value of rms SPL over all time window positions is taken to represent the rms SPL of the 

pulse. 
Gulf of Mexico G&G Activities Programmatic EIS D-9 

The sound exposure level (SEL) (LE, dB re 1 μPa2

·s) is the time integral of the squared pressure in a 

stated frequency band over a stated time interval or event. The per-pulse SEL is calculated over the time 

window containing the entire pulse (i.e., 100% of the acoustic energy), T100: 















 = ∫ οο

2 2

10

100

L 10 οg )(l pTdttp

T

E (5) 

where Tο is a reference time interval of 1 s by convention. The per-pulse SEL, with units of dB re 

1 μPa·√s, or equivalently dB re 1 μPa2

·s, is related, at least numerically, to the total acoustic energy flux 

density delivered over the duration of the acoustic event at a receiver location. SEL, unlike energy flux 

density, neglects the acoustic impedance of the medium (here water), which depends on density and 

sound speed and also on proximity to reflective surfaces and position within refractive environments. SEL 

is a measure of sound exposure through time rather than just sound pressure. 

SEL is a cumulative metric; it can be accumulated over a single pulse, or calculated over periods 

containing multiple pulses. To accumulate multiple pulse cumulative SEL (LEc), the single pulse SELs are 

summed. If there are N such pulses having individual SELs of (LEi), then: 















 = ∑=

N

i

Ei L

LE

1

10 c 10 10log10 (6) 

The SEL is related to the total acoustic energy flux density delivered over the duration of the set period of 

time, i.e., 24 h. It is a representation of the accumulated SEL delivered by multiple acoustic events, e.g., 

multiple pulses of a single acoustic source.

Because the rms SPL and SEL of a single pulse are computed from the same time integral of square 

pressure, these metrics are related numerically by a simple expression, which depends only on the 

duration of the 90% energy time window T90: 

log10 ( ) 458.0 LL pE 90 += T9010 + (7) 

where the factor of 0.458 dB accounts for the missing 10% of SEL due to consideration of just 90% of the 

cumulative square pressure in the Lp90 calculation. It is important to note that the decibel reference units 

of LE and Lp90 are not the same, so this expression must be interpreted only in a numerical sense. No 

similar relationship exists when SPL is calculated using fixed time windows shorter than the full pulse 

duration, T100; however, if the window length T is equal to or greater than T100 then the relationship is 

simply:

LL pE += log10 10 ( ) T (8) 

3.3. Use of Sounds by Marine Species

Sounds tend to travel farther than light in water. Many marine species use underwater acoustic signals as 

their principal mode of information transfer. Cetaceans (whales, dolphins, and porpoises) and sirenians 

(manatees and dugongs) use sounds passively, when listening to the environment, and actively, when 

communicating or foraging. Cetaceans in particular are heavily dependent on sounds for communicating, 

avoiding predators, foraging, and likely for navigating. Anthropogenic sounds in the ocean might interfere 

with basic life functions of marine species, especially marine mammals. 
D-10 Acoustic Propagation and Marine Mammal Exposure Modeling

3.3.1. Cetacean Hearing

Marine mammals have broader hearing frequency ranges than terrestrial mammals, an indication of how 

important sounds are to them. Because marine mammals evolved from terrestrial mammals, their basic 

hearing anatomy and physiology resembles that of their terrestrial ancestors. Divergence between 

terrestrial and marine mammals is primarily apparent in their outer ear structures—absent in cetacean 

species—and in the middle ear—modified in marine mammals (Mooney et al. 2012). 

The majority of detailed data on hearing ranges come from a subset of trained small cetaceans housed in 

captive settings who are amenable to training (see Southall et al. 2007 for review). Direct hearing data are 

not available for most of the cetacean species, particularly larger whales, but biophysical procedures and 

mathematical models have been developed to try to derive audiograms (e.g. Tubelli et al. 2012, Cranford 

and Krysl 2015) for many mysticete species. In addition, measurements of auditory evoked potentials 

(AEP) to determine hearing ranges have been successful when applied to some stranded animals 

(reviewed by Mooney et al. 2012). 

3.3.1.1. Classification of Cetacean Hearing 

Southall et al. (2007) categorized cetaceans into three functional hearing groups: low-, mid-, and highfrequency cetaceans (Table 1). These groups were defined based on similarities in their known or 

assumed hearing capabilities rather than their taxonomy. 

All low-frequency hearing specialists among cetaceans are mysticetes (baleen whales), which consist of 

seven species in five genera. Wartzok and Ketten (1999) found mysticetes to be most sensitive to sounds 

with frequencies in the tens of hertz to lower tens of kilohertz. Some findings, however, suggest that 

humpback whales (Megaptera novaeangliae) produce signals with harmonics extending above 24 kHz 

(Au et al. 2006). Computational models of the minke whale (Balaenoptera acutorostrata) middle ear 

predicted that their hearing frequency range is between 100 Hz and 30 kHz (Tubelli et al. 2012). 

Modeling based on computer tomography scans of a juvenile fin whale (Balaenoptera physalus) ear 

predicted their best hearing range is between 20 Hz and 20 kHz (Cranford and Krysl 2015). All of these 

findings suggest mysticete body size and hearing range are related, with larger whales being sensitive to 

very low frequencies (< 100 Hz) and smaller mysticetes hearing higher frequencies (> 20 kHz) better than 

their larger counterparts. From a functional perspective, all cetaceans should be able to hear the important 

frequencies in signals they produce and to hear predators well. For most cetaceans, including all 

mysticetes, killer whales are their primary predator. Killer whales produce broadband signals (calls and 

clicks) with a large portion of signal energy between 1 and 25 kHz. This frequency range is detectable by 

all cetaceans including low frequency specialists.

Mid- and high-frequency cetaceans are all odontocetes (toothed whales) who have a broad (150 Hz to 

180 kHz) functional hearing frequency range. They use echolocation (biosonar) at intermediate to high 

frequencies (tens of hertz to tens of kilohertz), and produce social sounds in the lower frequency range 

(one kHz to tens of kHz). 

Mid-frequency cetacean adults have a large range in size. This group includes dolphins, larger toothed 

whales, such as sperm whales, and beaked whales and bottlenose whales (Hyperoodon ampullatus; 

Southall et al. 2007). Mid-frequency cetaceans are estimated to have lower and upper frequency limits of 

nominal hearing at approximately 150 Hz and 160 kHz, respectively (Table 1). 

High-frequency cetaceans are typically characterized by a smaller body size and include, notably, 

porpoises, but also dwarf and pygmy sperm whales (Kogia sp.; Southall et al. 2007). High-frequency 

cetaceans produce echolocation clicks in a wide range of frequencies, which correspond well with the 

estimated lower and upper frequency limits of nominal hearing at approximately 200 Hz and 180 kHz, 

respectively (Table 1).
Gulf of Mexico G&G Activities Programmatic EIS D-11

Table 1. Marine mammal functional hearing groups, auditory bandwidth (estimated lower to upper frequency 

hearing cut-off), and genera represented in each group. Modified from Southall et al. (2007). 

Functional 

hearing group

Estimated 

auditory 

bandwidth

Genera represented in the Gulf of Mexico Number of 

species/subspecies

Low-frequency 

cetaceans

7 Hz to 

22 kHz Balaenoptera 1 

Mid-frequency 

cetaceans

150 Hz to 

160 kHz

Steno, Tursiops, Stenella, Lagenodelphis, Grampus, 

Peponocephala, Feresa, Pseudorca, Orcinus, Globicephala, 

Physeter, Ziphius, Mesoplodon

18 

High-frequency 

cetaceans

200 Hz to 

180 kHz Kogia 2 

3.4. Potential Effects of Sounds on Marine Mammals

The sounds that marine mammals hear and generate vary in characteristics such as dominant frequency, 

bandwidth, energy, temporal pattern, and directivity. The environment often contains multiple cooccurring sounds and, like all animals, marine mammals must be able to discriminate signals (meaningful 

sounds) from background sounds. Just as terrestrial animals integrate multiple stimuli from their visual 

landscape, marine mammals tend to discriminate among multiple stimuli in their acoustic seascape. 

Responses of marine mammals exposed to underwater anthropogenic sounds are variable and range from 

no effect to injury. The magnitude of the effect appears to depend on a combination of various factors, 

such as spatial relationships between a sound source and the animal, hearing sensitivity of the animal, 

received sound exposure, duration of exposure, duty cycle, and ambient sound level. Among other 

ecological factors, the animal’s activity at time of exposure and its history of exposure and familiarity 

with the noise signal are important influences. 

The potential effects of sounds on individual marine mammals can be broadly categorized as follows 

(based on Richardson et al. 1995, Southall et al. 2007): 

• Trauma and death 

• Temporary and permanent hearing loss 

• Non-auditory health effects

• Self-stranding 

• Auditory signal masking

• Behavioral disturbance

• Reduced availability of prey 

All of these effects can lead to potential removal of individuals and subsequent population consequences. 

Sections 3.4.1–3.4.5 briefly discuss several of these effects. 

3.4.1. Auditory Signal Masking

Auditory signal masking is the reduction in an animal’s ability to perceive, recognize or decode 

biologically relevant sounds because of interfering sounds. Masking may lead to altered communications 
D-12 Acoustic Propagation and Marine Mammal Exposure Modeling

and, potentially, increased metabolic costs (for example, due to increased call amplitude and repetition). 

The amplitude, timing, and spectral content of the interfering sounds determine the amount of masking an 

animal experiences. Masking can decrease the range over which an animal communicates, detects 

predators, or finds food. 

The study of masking in the ocean has traditionally focused on interactions between shipping sounds and 

mysticetes because these whales communicate using low-frequency calls in the same frequency bands as 

shipping sounds (Payne and Webb 1971). Over the past 50 years commercial shipping, the largest 

contributor of masking noise (McDonald et al. 2008), has increased the ambient sound levels in the deep 

ocean at low frequencies by 10–15 dB (Hatch and Wright 2007). Hatch et al. (2012) estimate that calling 

North Atlantic right whales (Eubalaena glacialis) might have lost, on average, 63–67% of their active 

acoustic or communication space due to shipping noise. 

Sounds from seismic surveys contribute to ocean-wide masking (Hildebrand 2009). Impulse sounds 

produced during pile driving operations in particular in connection with wind farm installations have been 

found to mask the calls of marine mammals at great distances (Madsen et al. 2006). Gordon et al. (2003) 

listed a range of possible effects of seismic impulses on cetacean behavior and communication including 

masking of sounds used during foraging, such as echolocation. 

Cumulative effects of seismic operations and other anthropogenic sound on marine mammals is poorly 

understood, but there is increasing concerns about masking by ship sounds at higher frequency ranges 

(e.g., up to 30 kHz; Arveson and Vendittis 2000); (up to 44.8 kHz; Aguilar Soto et al. 2006) at distances 

up to at least 700 m from the source (Aguilar Soto et al. 2006). Aguilar Soto et al. (2006) recorded a 

passing vessel on a Digital Acoustic Recording Tag (DTAG) attached to a Cuvier’s beaked whale. This 

recording demonstrated that vessel sounds masked the whale’s ultrasonic vocalizations and reduced its 

maximum communication range by 82% when ambient sound levels increased 15 dB in the vocalization 

frequencies. The study also determined that the effective detection distance of Cuvier’s beaked whales’ 

echolocation clicks was reduced by 58%. It is important to note, however, that these calculations are 

based on observed noise increases at high frequencies from a single passing vessel at close range, and that 

noise profiles from ships are highly variable, and high-frequency components attenuate more rapidly than 

do low frequencies (Hatch and Wright 2007). The reduction in communication space Cuvier’s beaked 

whales would experience at greater distance from the source is much lower. 

3.4.2. Behavioral Disturbance

The extent by which an animal’s behavior changes in response to underwater sounds can vary greatly, 

even within the same species (Nowacek et al. 2004). The extent of an individual’s response to a stimulus 

is influenced largely by the context in which the stimulus is received and the relevance that an individual 

attributes to the acoustic stimulus. The perceived relevance depends on a number of biological and 

environmental factors, such as age, sex, and behavioral state at the time of exposure (e.g., resting, 

foraging, or socializing), the origin of the sounds, and the proximity of the sound source. An immediate 

response to anthropogenic sounds is that animals temporarily avoid or move away from an ensonified 

area; however, they might also respond more conspicuously based on how close the sound sources are. 

For instance, their vigilance, defined as scanning for the source of the stimulus, could increase. The more 

time an animal invests in addressing noise means less time they can spend foraging (Purser and Radford 

2011), but this is not always easy to detect. 

Marine mammals have reduced their vocalization rates in response to anthropogenic sounds, sometimes 

not calling for weeks or months (IWC 2007). Some cetaceans might compensate for masking, to a limited 

degree, by increasing the amplitude of their calls (the Lombard effect, a known response of humans to 

noise) or by changing vocalization properties such as frequency content (Parks et al. 2010, Hotchkin and 

Parks 2013). As ambient noise levels increase, killer whales have been known to increase the amplitude 
Gulf of Mexico G&G Activities Programmatic EIS D-13

of their calls (Holt et al. 2009). North Atlantic right whales produced calls with a higher average 

fundamental frequency and lowered their call rates in high noise conditions (Parks et al. 2007, Parks et al. 

2009), whereas blue whales (Balaenoptera musculus) increased the frequency of their discrete, audible 

calls during a seismic survey (Di Iorio and Clark 2010) or when nearby ships made sounds (Melcon et al. 

2012). A long signal or one that repeats could reduce an animal’s ability to perceive biologically relevant 

sounds in a noisy environment. Whales seem most reactive at the onset of a sound and when the sound 

levels are increasing rapidly. All of these responses increase an animal’s metabolic costs and, depending 

on the animal’s metabolic state and the duration of its response, can negatively affect its health.

Although limited, some data suggest that stationary industrial activities that produce continuous sounds 

such as dredging, drilling, and oil-production-related activities, cause cetaceans to react less than sounds 

produced by moving sources, particularly ships. Some cetaceans might behaviorally habituate to reliably 

occurring continuous sounds (Richardson et al. 1995), a response that has also been observed in humans 

where some physiological habituation (lower endocrine stress responses) to prolonged noise exposure can 

occur. However, the act of responding could indirectly affect health through related physiological 

responses, such as cardiovascular stress responses (e.g., increased blood pressure; Christal and Whitehead 

2001). 

Stone and Tasker (2006) reported that airgun sounds elicited strong reactions—moving away from or 

avoiding an ensonified area—by small odontocetes. Mysticetes and killer whales responded by diverting 

paths and long-finned pilot whales changed their orientation. Controlled exposure experiments were 

conducted with eight tagged sperm whales over a series of 30-min intervals during pre-exposure, rampup, and full-array airgun firing (Miller et al. 2009). Results showed seven whales did not avoid airgun 

sounds. They did not change their buzz rates; however, oscillations in pitch were affected. Following the 

final airgun transmission, only one individual rested at the surface during the sound exposure and dove 

immediately thereafter. Miller et al. (2009) concluded that sperm whales in the highly exposed Gulf of 

Mexico habitat do not show any significant avoidance response to airguns, a lack of reaction that Rankin 

and Evans (1998) also noticed, but exhibited subtle effects on their foraging behavior. 

Others suggested some mysticetes might change their habitat usage considerably after they are exposed to 

seismic sounds. During the first 72 h of a 10-day seismic survey, fin whales appeared to move away from 

the airgun array; this displacement persisted well beyond the 10 days of seismic airgun activity 

(Castellote et al. 2012). It was unknown, however, if the whales were avoiding the sound or following 

another cue such as a prey. McDonald et al. (1995) observed blue whales’ responses to airgun firing. 

They stopped singing within a 10 km radius of the source, although this could have been a direct response 

to avoid their sounds being masked. 

For reactions to pulsed sounds specifically, there is evidence that the behavioral state 

(traveling/migrating, foraging, resting, or socializing) of baleen whales exposed to seismic sounds 

(McCauley et al. 1998, Gordon et al. 2003), combined with their proximity to the airguns, affects how the 

whales react to the sounds. Several species of baleen whales showed avoidance behavior to sounds from 

seismic surveys (Richardson et al. 1995); bowhead whales (Balaena mysticetus) avoided distant seismic 

airguns at received levels of rms SPL of 120–130 dB re 1 μPa during their fall migration (Richardson et 

al. 1999). Feeding bowhead whales in the summer were more tolerant to airgun sounds avoiding airguns 

only when received levels reached 152–178 dB re 1 μPa, which is roughly 10,000 times louder than 

avoidance levels of the migrating whales (Richardson et al. 1995). Different sexes might also react 

differently when exposed to seismic signals. Resting female humpback whales avoided seismic surveys 

by diverting their travel paths to remain 7–12 km away, while males were occasionally attracted to the 

sounds (McCauley et al. 2000b). 

For other pulsed sound sources, Brandt et al. (2011) and (Dähne et al. 2013) reported that harbor 

porpoises (Phocoena phocoena) were displaced from an area by pile driving noises, a repeating impulsive 

sound, while male humpback whales either moved out of a study area or sang less when exposed to 
D-14 Acoustic Propagation and Marine Mammal Exposure Modeling

frequency-modulated pulses that were 200 km away (Risch et al. 2012). Humpback whales also 

lengthened their mating songs when they were exposed to low-frequency active (LFA) sonar (Miller et al. 

2000). Long-finned pilot whales whistled more in response to military mid-frequency sonar (Rendell and 

Gordon 1999). Castellote et al. (2012) noted that in response to shipping and airgun noise, fin whale calls 

were of shorter duration, lower frequency ranges, and lowered center and peak frequencies.

In their review of the effect of non-pulsed (continuous) sounds on cetaceans, Southall et al. (2007) 

reported that low-frequency cetaceans exhibited no or limited responses with received levels up to 120 dB 

re 1 μPa, but an increasing probability of avoidance (and other behavioral responses) beginning at 

received levels between 120 to 160 dB re 1 μPa. Reports of possible behavioral responses to non-pulsed 

sounds include harbor porpoises (high-frequency cetaceans) that generally swam away from approaching 

vessels (Polacheck and Thorpe 1990) or moved rapidly out of the way of an approaching survey vessel 

when the vessel was 1 km away (Barlow 1988). In both studies, however, it was unclear whether it was 

the approaching vessel or its sound that elicited the response, although reacting at 1 km suggests the 

animal was reacting to the sound. 

Aguilar Soto et al. (2006) noted a Cuvier’s beaked whale responding to ship sounds by decreasing the 

vocalizations they normally make when trying to catch prey. Blainville’s beaked whales changed their 

foraging after they were exposed to vessel noise (Pirotta et al. 2012). Groups of Pacific humpback 

dolphins (Sousa chinensis) that contained mother-calf pairs increased their whistling rate after a boat had 

transited the area (Van Parijs and Corkeron 2001). The authors postulated that vessel sounds disrupted 

group cohesion, especially between mother-calf pairs, requiring the group to re-establish vocal contact 

after signal masking from boat noise. In responses to high levels of boat traffic, the duration (Foote et al. 

2004) or the amplitude (Holt et al. 2009) of killer whale calls increased. Common bottlenose dolphins 

produced more whistles when boats approached (Buckstaff 2004). 

3.4.3. Temporary and Permanent Hearing Loss

Physical impacts to an animal’s auditory system can occur from exposure to intense sounds and can result 

in the animal losing hearing sensitivity. A temporary threshold shift (TTS) is hearing loss that persists 

only for minutes or hours, whereas a permanent threshold shift (PTS) is indefinite. The severity of TTS is 

expressed as the duration of hearing impairment (lowered sensitivity in the bandwidths in which the noise 

was centered) and the magnitude of the shift in hearing sensitivity relative to pre-exposure sensitivity. 

TTS generally occurs at lower sound levels than PTS. Repeated TTS, especially if the animal is receiving 

another loud sound exposure before recovering from the previous TTS, is thought to cause PTS (Lin et al. 

2011). If the sound is intense enough, however, an animal can succumb to PTS without first experiencing 

TTS (Weilgart 2007). Though the relationship between the onset of TTS and the onset of PTS is not fully 

understood, TTS onset is used to predict sound levels that are likely to result in PTS. 

Recent studies have modeled the potential impacts (TTS: Kremser et al. 2005; PTS: Lurton and DeRuiter 

2011) of echosounders on marine mammals. The results from the studies suggest that TTS and PTS occur 

generally at distances of 100 m or less and most important, only apply in the cone ensonified by the 

modeled echosounders, meaning only animals below the ship are exposed to these levels. Animals at the 

same distances but to the sides of the vessel will be exposed to lower levels. 

Experiments with captive common bottlenose dolphins have shown that loud, short (1 s) tonal sounds can 

cause TTS (Schlundt et al. 2000), as can lower sound level exposures for periods up to 50 min (Finneran 

et al. 2005, Nachtigall et al 2005, Nachtigall et al. 2004). Impulsive sounds from a watergun (Finneran et 

al. 2002) or an airgun (Lucke et al. 2009) have also been shown to cause TTS in beluga whales and harbor 

porpoises, respectively. Cook (2006) found that captive odontocetes typically experienced more hearing 

loss than similar-aged free-ranging dolphins. Older captive common bottlenose dolphins are known to 

have reduced hearing sensitivity, especially at higher frequencies, but whether the cause of this hearing 
Gulf of Mexico G&G Activities Programmatic EIS D-15

loss is related to captivity is unknown (Ridgway and Carder 1997); it could simply be the phenomenon of 

reduced high frequency sensitivity with age that occurs in humans. 

3.4.4. Non-Auditory Health Effects

Scientists have studied the physiological stress response of captive marine mammals to noise. When 

Thomas et al. (1990) played drilling noise to four captive beluga whales, they measured their stress 

hormone levels (blood adrenaline/epinephrine and noradrenaline/norepinephrine) immediately after 

playback and found no changes in them. After exposing a captive common bottlenose dolphin and a 

captive beluga whale to sounds from a seismic watergun, Romano et al. (2004) found changes in some 

hormones and blood cell counts—from the common bottlenose dolphin, with aldosterone and monocytes 

levels; from the beluga, epinephrine, norepinephrine, and dopamine levels. Miksis et al. (2001) found that 

the heart rate in a captive common bottlenose dolphin increased in response to threat sounds produced by 

other dolphins. Rolland et al. (2012) demonstrated that exposing right whales to low-frequency ship noise 

might be associated with chronic stress. 

Crum and Mao (1996) hypothesized that when marine mammals are exposed to high-intensity lowfrequency sounds, gas bubbles might form in their tissues, a process called rectified diffusion. The 

physiological state of a diving cetacean when it is exposed to sounds determines its susceptibility to 

rectified diffusion. Diving speed and depth of diving are the primary determinants of the amount of 

nitrogen that can accumulate in tissues, with slower rates of ascent/descent and deeper dives increasing 

gas supersaturation (accumulation of higher levels of nitrogen than would be possible at atmospheric 

pressure). Acoustic activation or generation of bubble nuclei before the animal surfaces or when it is just 

at the surface, can theoretically drive bubbles to grow rapidly by the degree of supersaturation and the 

animal’s continued exposure to sounds (Houser et al. 2001). Bubble growth can damage tissue and block 

blood vessels. In deep-diving marine mammals, such as beaked whales, Fernández et al. (2005) calculated 

supersaturation at over 300%, and found bubbles in some stranded beaked whales’ tissues.

Animals that change their behavior in response to sounds could injure themselves. Although the sound 

characteristics and behavioral and physiological mechanisms behind strandings are not fully understood, 

some scientists believe acoustic exposure might be a culprit, noting particularly the association between 

military mid-frequency sonar and strandings of melon-headed whales (Southall et al. 2006, 2013), beaked 

whales (D'Amico et al. 2009) and common dolphins (Jepson et al. 2013). Because beaked whales are 

extreme divers that undergo gas supersaturation, exposure to sounds that induces them to ascend more 

rapidly might put them at risk of tissue-damaging nitrogen bubbles forming, similar to decompression 

sickness that human divers experience (Cox et al. 2006). Alternatively, if beaked whales remain 

submerged longer because of acoustic exposure, hypoxia could damage their tissues (Cox et al. 2006). 

3.4.5. Reduction of Prey Availability 

Sound might indirectly affect marine mammals by altering prey abundance, behavior, and distribution. 

Rising sound levels could affect fish populations (McCauley et al. 2003, Popper and Hastings 2009, 

Slabbekoorn et al. 2010). Marine fish are typically sensitive to the 100–500 Hz range, where most seismic 

sounds are produced. 

Several studies have demonstrated that anthropogenic sounds might affect the behavior of at least some 

species of fish. For example, field studies by Engås et al. (1996) and Whitlock and Schluter (2009) 

showed that when seismic airguns were operating the catch rate of haddock (Melanogrammus aeglefinus) 

and Atlantic cod (Gadus morhua) significantly declined over the five days following, after which the 

catch rate returned to normal. Engås et al. (1996) and Whitlock and Schluter (2009) suggested that the 

catch rate declined because fish were responding to the sounds of the airguns by avoiding the area of 
D-16 Acoustic Propagation and Marine Mammal Exposure Modeling

ensonification. Slotte et al. (2004) showed parallel results for several other pelagic species. Fish near the 

airguns appeared to move to greater depths after being exposed to airguns. Moreover, because the number 

of fish 30–50 km away from the ensonification area increased, it seems likely that migrating fish avoided 

the seismic activity zone. Other studies found only minor responses by fish to noise created during or 

following seismic surveys, such as a small decline in lesser sandeel (Ammodytes marinus) abundance that 

quickly returned to pre-seismic levels (Hassel et al. 2004), or no permanent changes in the behavior of 

marine reef fishes (Wardle et al. 2001). Both Hassel et al. (2004) and Wardle et al. (2001), however, 

noted that when fish saw the airgun firing they performed a startle response and sometimes fled.

Squid (Sepioteuthis australis) are an extremely important food chain component for many higher order 

predators, including sperm whales. McCauley et al. (2000b) recorded caged squid responding to airgun 

signals. They exhibited strong startle responses to a nearby airgun starting up: they fired their ink sacs 

and/or jetted away from the airgun source. Squid also avoided the airgun by staying close to the water 

surface near the cage end farthest from the airgun. 

The effects of sounds on fish and squid are still poorly understand. Although some fish additionally sense 

pressure, all fish and squid sense particle motion, and particle motion is not always directly related to

pressure measurements. While no studies have investigated the indirect effects of seismic airguns on 

marine mammals’ prey availability, it is possible that seismic surveys could change the feeding 

opportunities available to marine mammals, especially in cases of restricted foraging locations. 
Gulf of Mexico G&G Activities Programmatic EIS D-17

4. Marine Mammals in the Gulf of Mexico 

Twenty-one cetacean species have been sighted in marine mammal surveys since 1991(Waring et al. 

2013). Eighteen are mid-frequency hearing specialists. Bryde’s whales are the only low-frequency 

species. Dwarf and pygmy sperm whales comprise the only high-frequency hearing specialist group. 

Table 2 lists these species, their functional hearing group, and preferred habitat. Determining the risk of 

acoustic exposure to a population of animals requires an estimate of the number of animals in that area. 

Occurrence and abundance estimates are determined from surveys that identify, count, and log the 

position of species in various waters. From these data, models have been created to provide estimates of 

likely densities) along transect lines and between lines. In Phase I, the Navy’s U.S. Navy OPAREA

Density Estimate (NODE; DoN 2007) model was used to obtain animal density estimates (see 

Section 6.2.5). In Phase II, density estimates were obtained from the Marine Geospatial Ecology 

Laboratory at Duke University preliminary results (Roberts et al. In preparation; see Section 7.2.6). 
D-18 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 2. Marine mammal species considered in the acoustic exposure analysis.

Common name Latin binomial Functional 

hearing group Preferred habitat

Atlantic spotted dolphins Stenella frontalis MFC Primarily coastal (< 200 m)

Beaked whales spp. 

(Cuvier’s, Blainville’s, 

Gervais’)

Mesoplodon densirostris, 

Ziphius cavirostris, Mesoplodon 

europaeus

MFC Oceanic

Common bottlenose dolphins Tursiops truncatus MFC Primarily coastal (< 200 m), 

occasionally oceanic

Bryde’s whales Balaenoptera brydei/edeni LFC Oceanic

Clymene dolphins Stenella clymene MFC Oceanic

False killer whales Pseudorca crassidens MFC Oceanic

Fraser’s dolphins Lagenodelphis hosei MFC Oceanic

Killer whales Orcinus orca MFC Various

Kogia spp. 

(Dwarf sperm whales, 

Pygmy sperm whales)

Kogia sima, Kogia breviceps HFC Oceanic

Melon-headed whales Peponocephala electra MFC Oceanic

Pantropical spotted dolphins Stenella attenuata MFC Oceanic

Pygmy killer whales Feresa attentuata MFC Oceanic

Risso’s dolphins Grampus griseus MFC Oceanic

Rough-toothed dolphins Steno bredanesis MFC Oceanic

Short-finned pilot whales Globicephala macrorhyncus MFC Various

Sperm whales Physeter macrocephalus MFC Oceanic

Spinner dolphins Stenella longirostris MFC Oceanic

Striped dolphins Stenella coeruleoalba MFC Oceanic

LFC=Low-frequency cetacean; MFC=Mid-frequency cetacean; HFC=High-frequency cetacean.
Gulf of Mexico G&G Activities Programmatic EIS D-19

5. Modeling Methodology

5.1. Acoustic Source Model

5.1.1. Airgun and Airgun Array Modeling Methodology

The source levels and directivity of the airgun array were predicted with JASCO’s Airgun Array Source 

Model (AASM; Austin et al. 2010). This model is based on the physics of oscillation and radiation of 

airgun bubbles described by Ziolkowski (1970). The model solves the set of parallel differential equations 

that govern bubble oscillations. AASM also accounts for nonlinear pressure interactions between airguns, 

port throttling, bubble damping, and generator-injector gun behavior that are discussed by Dragoset 

(1984), Laws et al. (1990), and Landro (1992). AASM includes four empirical parameters that were tuned 

so that model output matches observed airgun behavior. The model was originally fit to a large library of 

empirical airgun data using a simulated annealing global optimization algorithm. These airgun data 

consisted of measured signatures of Bolt 600/B airguns ranging in volume from 5 to 185 in3 (Racca and 

Scrimger 1986). 

While airgun signatures are highly repeatable at the low frequencies used for seismic imaging, their sound 

emissions have a random component at higher frequencies that cannot be predicted using a deterministic 

model. Therefore, AASM uses a stochastic simulation to predict the high-frequency (560−25,000 Hz) 

sound emissions of individual airguns, using a data-driven multiple-regression model. The multipleregression model is based on a statistical analysis of a large collection of high quality seismic source 

signature data recently obtained from the Joint Industry Program (JIP) on Sound and Marine Life 

(Mattsson and Jenkerson 2008). The stochastic model uses a Monte-Carlo simulation to simulate the 

random component of the high-frequency spectrum of each airgun in an array. The mean high-frequency 

spectra from the stochastic model augment the low-frequency signatures from the physical model, making 

AASM capable of predicting airgun source levels at frequencies up to 25,000 Hz.

AASM produces a set of notional signatures for each airgun element based on: 

• Array layout

• Volume, tow depth, and firing pressure of each airgun 

• Interactions between different airguns in the array

These notional signatures are the pressure waveforms of the individual airguns at a standard reference 

distance of 1 m; they account for the interactions with the other airguns in the array. The signatures are 

summed with the appropriate phase delays to obtain the far-field2 source signature of the entire array in 

the horizontal plane. This far-field array signature is filtered into 1/3-octave passbands to compute the 

source levels of the array as a function of frequency band and azimuthal angle in the horizontal plane (at 

the source depth), after which it is considered to be an azimuth-dependent directional point source in the 

far field.

 

2  The  far  field  is  the  zone  where,  to  an  observer,  sound  originating  from  a  spatiallydistributed  source  appears to radiate  from  a  single  point. The distance to the acoustic far field increases 

with frequency. 
D-20 Acoustic Propagation and Marine Mammal Exposure Modeling

A seismic array consists of many sources. The point-source assumption is invalid in the near field where 

the array elements add incoherently. The maximum extent of the near field of an array (Rnf) is:

4λ

2

λ Rnf < (9) 

where λ is the sound wavelength and l is the longest dimension of the array (Lurton 2002 Section 5.2.4). 

For example, an airgun array length of l ≈ 16 m yields a near-field range of 85 m at 2 kHz and 17 m at 

100 Hz. Beyond Rnf range, the array is assumed to radiate like a directional point source and is treated as 

such for propagation modeling. 

The AASM accurately predicts the source level of the complete array as a point source for acoustic 

propagation modeling in the far field; however, predicted source levels for zero-to-peak SPL and sound 

exposure level (SEL) metrics might be higher than the possible maximum levels during the array 

operation even within the array. 

The interactions between individual elements of the array create directionality in the overall acoustic 

emission. Generally, this directionality is prominent mainly at frequencies in the mid-range between tens 

of hertz to several hundred hertz. At lower frequencies, with acoustic wavelengths much larger than the 

inter-airgun separation distances, the directionality is small. At higher frequencies, the pattern of lobes is 

too finely spaced to be resolved and there is less effective directivity.

5.1.2. Electromechanical Source Modeling—Transducer Beam Theory

Mid- and high-frequency underwater acoustic sources for geophysical measurements create an oscillatory 

overpressure by either electromagnetic forces or the piezoelectric effect rapidly vibrating the surface of 

the source. A vibratory source based on the piezoelectric effect is commonly referred to as a transducer, 

and piezo transducers are often able to receive and emit signals. Transducers are usually designed to 

produce an acoustic wave of a specific frequency, often in a highly directive beam. The directional 

capability increases with increasing operating frequency. The main parameter characterizing directivity is 

beamwidth, defined as the angle subtended by diametrically opposite half power (−3 dB) points of the 

main lobe (Massa 2003). Depending on the frequency and size of the transducer, the beamwidth can vary 

from 180° (almost omnidirectional) to less than 1 degree.

Transducers are commonly designed with either circular or rectangular active surfaces. For circular 

transducers, the beamwidth in the horizontal plane (assuming a downward pointing main beam) is equal 

in all directions. Rectangular transducers produce more complex beam patterns with variable beamwidth 

in the horizontal plane; two beamwidth values are usually specified for orthogonal axes. 

The acoustic radiation pattern, or beam pattern, of a transducer is the relative measure of acoustic 

transmitting or receiving power as a function of spatial angle. Directionality is generally measured in 

decibels relative to the maximum radiation level along the central axis perpendicular to the transducer 

surface. The pattern is defined largely by the operating frequency of the device and the size and shape of 

the transducer. Beam patterns generally consist of a main lobe, extending along the central axis of the 

transducer, and multiple secondary lobes separated by nulls. The width of the main lobe depends on the 

size of the active surface relative to the sound wavelength in the medium, with larger transducers 

producing narrower beams. Figure 1 presents a 3-dimensional (3-D) visualization of a generic beam 

pattern of a circular transducer. 

The true beam pattern of a transducer can be obtained only by measuring the emitted energy around the 

device when it is in place. Such data, however, are not always available. For propagation modeling, 

estimating the beam pattern of the source based on transducer beam theory often suffices. An example of 

a measured beam pattern is shown in Figure 2. 
Gulf of Mexico G&G Activities Programmatic EIS D-21

Figure 1. Typical 3-D beam pattern for a circular transducer (Massa 2003). 

Figure 2. Vertical cross section of a beam pattern measured in situ from a transducer used by Kongsberg 

(pers. comm. with the manufacturer). 

5.1.2.1. Circular Transducers

The beam of an ideal circular transducer is symmetric about the main axis; the radiated level depends 

only on the depression angle. In this study, beam directivities were calculated from the standard formula 

for the beam pattern of a circular transducer (ITC 1993, Kinsler et al. 2000). The directivity function of a 

conical beam relative to the on-axis pressure amplitude is: 

( )

sin( )

2 sin( ) )( 1

φπ

φπ⋅ =φ

λ

λ

D

DJ R and 

bw

D

θ λ = 60 , (10) 
D-22 Acoustic Propagation and Marine Mammal Exposure Modeling

where J1(φ) is the first-order Bessel function, Dλ is the transducer dimension in wavelengths of sound in 

the medium, θbw is the beamwidth in degrees, and φ is the beam angle from the transducer axis. The beam 

pattern of a circular transducer can be calculated from the transducer’s specified beamwidth or from the 

diameter of the active surface and the operating frequency. The calculated beam pattern for a circular 

transducer with a beamwidth of 20° is shown in Figure 3. The grayscale represents the source level (dB re 

1 μPa @ 1 m) and the declination angle is relative to a central vector (0°, 0°) pointing down. 

Although some acoustic energy is emitted at the back of the transducer, the theory accounts for the beam 

power in only the front half-space (φ < 90°) and assumes no energy directed into the back half-space. The 

relative power at these rearward angles is significantly lower, generally by more than 30 dB, and 

consequently the emission in the back half-space can be estimated by applying a simple decay rate, in 

decibels per angular degree, which gives a beam power at φ = 90° of 30 dB less than that at φ = 0°. This is 

a conservative estimate of the beam power in the back half-space. 

Figure 3. Calculated beam pattern for a circular transducer with a beamwidth of 20°. The beam power 

function is shown relative to the on-axis level.

5.1.2.2. Rectangular Transducers

Rectangular transducer beam directivities were calculated from the standard formula for the beam pattern 

of a rectangular acoustic array (ITC 1993, Kinsler et al. 2000). The directivity function is the product of 

the toroidal beam patterns of two line arrays, where the directional characteristics in the along- and 

across-track directions are computed from the respective beamwidths. The directivity function of a 

toroidal beam relative to the on-axis pressure amplitude is:

( )

sin( )

sin(sin ) )( φπφπ =φ

λ

λ

L

L R and 

bw

L

θ λ = 50 , (11) 

where Lλ is the transducer dimension in wavelengths, θbw is the beamwidth in degrees, and φ is the angle 

from the transducer axis. The beam pattern of a transducer can be calculated using either the specified 

beamwidth in each plane or the dimensions of the active surface and the operating frequency of the 

transducer. The calculated beam pattern for a rectangular transducer with along- and across-track 

beamwidths of 4° and 10°, respectively, is shown in Figure 4. 
Gulf of Mexico G&G Activities Programmatic EIS D-23

Figure 4. Calculated beam pattern for a rectangular transducer with a 4° × 10° beamwidth. The beam 

power function is shown relative to the on-axis level using the Robinson projection. 

5.1.2.3. Multibeam Systems

High-frequency systems often have two or more transducers, e.g., side-scan and multibeam sonar. Typical 

side-scan sonar use two transducers, with the central axes directed perpendicular to the survey track and 

at some depression angle below the horizontal. In contrast, multibeam bathymetry systems can have 

upward of 100 transducers. Such systems generally consist of rectangular transducers and have a narrow 

beamwidth in the horizontal (along-track) plane (0.2–3°) and a wide beamwidth in the vertical (acrosstrack) plane.

For multibeam systems, the beam patterns of individual transducers are calculated separately and then 

combined into the overall pattern of the system based on beam engagement types, which can be broadcast 

simultaneously or successively. If the beams are engaged successively, the source level of the system in a 

given direction is assumed to be the maximum source level realized from the individual transducers; if the 

beams are engaged simultaneously, the system beam pattern is the sum of all beam patterns. Figure 5

shows the predicted beam pattern for two rectangular transducers engaged simultaneously. These 

transducers have along- and across-track beamwidths of 1.5° and 50°, respectively. 

Figure 5. Calculated beam pattern for two rectangular transducers engaged simultaneously, with 

individual beamwidths of 1.5° × 50°, and a declination angle of 25°. The beam power 

function is shown relative to the on-axis level using the Robinson projection. 
D-24 Acoustic Propagation and Marine Mammal Exposure Modeling

5.2. Acoustic Propagation Modeling

The underwater sound propagation (i.e., transmission loss) was predicted with JASCO’s Marine 

Operations Noise Model (MONM). This model computes received per-pulse SEL for directional sources 

at a specified depth. 

5.2.1. Two Frequency Regimes: RAM vs. BELLHOP

In order to achieve the greatest accuracy and computational efficiency, MONM uses two separate models 

to estimate transmission loss. At frequencies ≤ 2 kHz, MONM computes acoustic propagation via a wideangle parabolic equation solution to the acoustic wave equation (Collins 1993) based on a version of the 

U.S. Naval Research Laboratory’s Range-dependent Acoustic Model (RAM), which has been modified to 

account for an elastic seabed (Zhang and Tindle 1995). The parabolic equation method has been 

extensively benchmarked and is widely employed in the underwater acoustics community (Collins et al. 

1996). The RAM-based component of MONM (MONM-RAM) accounts for the additional reflection loss 

at the seabed due to partial conversion of incident compressional waves to shear waves at the seabed and 

sub-bottom interfaces, and it includes wave attenuations in all layers. MONM-RAM’s predictions have 

been validated against experimental data in several underwater acoustic measurement programs 

conducted by JASCO (Hannay and Racca 2005, Aerts et al. 2008, Funk et al. 2008, Ireland et al. 2009, 

O'Neill et al. 2010, Warner et al. 2010). MONM-RAM incorporates the following site-specific 

environmental properties: a modeled area bathymetric grid, underwater sound speed as a function of 

depth, and a geoacoustic profile based on the overall stratified composition of the seafloor. MONM-RAM 

accounts for source horizontal directivity.

At frequencies ≥ 2 kHz, MONM employs the widely-used BELLHOP Gaussian beam ray-trace 

propagation model (Porter and Liu 1994), which accounts for increased sound attenuation due to volume 

absorption at these higher frequencies following Fisher and Simmons (1977). This type of attenuation is 

significant for frequencies higher than 5 kHz and cannot be neglected or model results far from the source 

will noticeably suffer. The BELLHOP component of MONM (MONM-BELLHOP) accounts for the 

source directivity, specified as a function of both azimuthal angle and depression angle. MONMBELLHOP incorporates the following site-specific environmental properties: a bathymetric grid of the 

modeled area and underwater sound speed as a function of depth. In addition to horizontal directivity of 

the source, MONM-BELLHOP accounts for the vertical variation of the source beam pattern.

In contrast to MONM-RAM, the geoacoustic input for MONM-BELLHOP consists of only one interface: 

the sea bottom. This is an acceptable limitation because the influence of the sub-bottom layers on the 

propagation of acoustic waves with frequencies above 1 kHz is negligible. Both propagation models 

account for full exposure from a direct acoustic wave, as well as exposure from acoustic wave reflections

and refractions (i.e., multi-path arrivals at the receiver). 

These propagation models effectively assume a continuous wave source. That is an acceptable 

approximation for a pulse in the case of the SEL metric because the energy in the various multi-path 

arrivals will be summed. When significant multi-path arrivals cause broadening of the pulse, the 

continuous wave assumption breaks down for pressure metrics such as rms SPL. For this reason, a subset 

of the modeling sites were selected to have acoustic propagation from the airgun array modeled using a 

full-wave RAM PE model (FWRAM), with which broadband SEL to SPL conversion factors could be 

calculated using a sliding 100 ms integration window. The modeling time required to perform these 

calculations (often several days for each site) made it prohibitive to perform them at any more than a 

representative subset of the modeling sites. These azimuth-, range- and depth-dependent conversion 

factors were then used to calculate the broadband rms SPL from the broadband SEL prediction at all the 

modeling sites. Conversion factors were calculated for each modeling location. 
Gulf of Mexico G&G Activities Programmatic EIS D-25

For geotechnical source propagation modeling, a fixed +10 dB factor was used to convert SEL to rms 

SPL. A fixed correction factor was used for simplicity because there was little variability over the range 

of propagation for the geotechnical sources. It is noted that 10 dB assumes the pulse length is 100 ms. 

Pulse lengths less than 100 ms would have greater than 10 dB conversion factors, but the minimal 

integration time for the mammalian ear is ~100 ms. Additional details about source directivity and 

propagation modeling are provided in Sections 5.1.1, 5.1.2, 5.2.2, 5.2.3, and 5.2.4. 

5.2.2. N×2-D Volume Approximation

MONM computes acoustic fields in three dimensions by modeling transmission loss within twodimensional (2-D) vertical planes aligned along radials covering a 360° swath from the source, an 

approach commonly referred to as N×2-D. These vertical radial planes are separated by an angular step 

size of ∆θ, yielding N = 360°/∆θ number of planes (Figure 6). 

Figure 6. The N×2-D and maximum-over-depth modeling approach. 

5.2.3. Frequency Dependence: Summing Over 1/3-Octave-Bands

MONM treats frequency dependence by computing acoustic transmission loss at the center frequencies of 

1/3-octave-bands. Sufficiently many 1/3-octave-bands, starting at 10 Hz, are modeled to include the 

majority of acoustic energy emitted by the source. At each center frequency, the transmission loss is 

modeled within each of the N vertical planes as a function of depth and range from the source. The 

1/3-octave-band received per-pulse SELs are computed by subtracting the band transmission loss values 

from the SL in that frequency band. 
D-26 Acoustic Propagation and Marine Mammal Exposure Modeling

Composite broadband received SELs are computed by combining the transmission loss (TL) values 

obtained from propagation modeling with MONM and source levels (SL) obtained from source modeling 

(see Section 5.1) in each 1/3-octave-band and summing the band levels: 

∑=

− ⋅=

n

i

ii

1

(SL TL 10)

10 10log10RL (12) 

where n is the number of modeled 1/3-octave-bands, SLi and TLi are the source level and transmission 

loss in the respective 1/3-octave-band. 

The frequency weighted received levels (RLMW) were obtained by adding the relative levels (MW) (see 

Section 5.4.1) to the above equation:

∑=

+− ⋅=

N

i

iii

1

(SL TL MW 10)

MW 10 10log10RL . (13) 

MONM’s predictions have been validated against experimental data from several underwater acoustic 

measurement programs conducted by JASCO (Hannay and Racca 2005, Aerts et al. 2008, Funk et al. 

2008, Ireland et al. 2009, O'Neill et al. 2010, Warner et al. 2010, Racca et al. 2012a, Racca et al. 2012b). 

5.2.4. Converting Modeled SEL to rms SPL

5.2.4.1. Background

Current National Marine Fisheries Service (NMFS) exposure criteria for impulsive sound sources are 

based largely on the rms SPL metric. As shown in Equations 7 and 8 in Section 3.2, the rms SPL metric is 

numerically related to the single pulse SEL and the integration time window for the cases of the 

commonly-used 90% window, T90, and for fixed integration windows greater than T100. These 

relationships are important because models are more efficient at estimating SEL than rms SPL. Therefore, 

in some cases models can be used to calculate the SEL of impulsive acoustic events, after which the 

aforementioned equations can be used to derive the corresponding rms SPL. 

Unfortunately, T90 is sensitive to the specific acoustic multipath arrival time of signals. Multipath arrival 

time varies greatly with source and receiver depths, distance of the receiver from the source, and the 

water depth profile between source and receiver. Water column refractive effects in deep waters, such as

those within deeper regions of the study area, can strongly influence the multipath arrival structure and 

consequently affect T90. Another problem arises when considering fixed time windows of duration shorter 

than T100; in these cases Equations 7 and 8 are not valid and cannot be used directly. 

Two methods are available to deal with the problems identified above: if field measurements in a similar 

environment are available, they can be analyzed to directly calculate differences between SEL and rms 

SPL. Those differences can then be applied to modeled SEL values to derive the corresponding rms SPL. 

The approach is limited to applications where measurements are available in a suitably similar 

environment and where the actual measurement source-receiver geometry spans the ranges and depths of 

interest. The second approach is to apply full-waveform models to calculate synthetic data from which the 

numeric differences between SEL and corresponding rms SPL can be predicted. This approach can 

address a much larger variety of ocean environments and source-receiver geometries.

Various empirical measurements of airgun pulses have shown that differences between rms SPL and SEL 

typically range from +15 to −5 dB (Greene 1997, McCauley et al. 1998, Blackwell et al. 2007, 

MacGillivray et al. 2007). The difference is highly sensitive to multipath arrival timing and reverberation, 

but it is generally larger at closer distances, where the airgun pulse duration is short (≪ 1 s), and smaller 
Gulf of Mexico G&G Activities Programmatic EIS D-27

at farther distances, where pulse duration tends to increase due to increased reverberation and larger 

differences in the arrival times of different propagation paths. 

5.2.4.2. Fixed Integration Time Window

For individual acoustic pulses, we used a fixed integration time window of 100 ms, the shortest expected 

temporal integration time for the mammalian ear (Plomp and Bouman 1959, MacGillivray et al. 2014). At 

this window length, the maximum numerical difference between SEL and rms SPL for an impulsive 

acoustic event is 10 dB. This maximum difference occurs when all of the pulse’s acoustic energy is 

received in less than 100 ms. As the pulse length increases beyond 100 ms, the difference decreases. A 

difference value of 0 dB (SEL = rms SPL), occurs when the acoustic energy is received evenly distributed 

over 1 s. 

We applied a nominal conversion difference of +10 dB from SEL to rms SPL at all receiver positions for 

all single airgun and geotechnical source types. The +10 dB results from the assumption that the shortest 

temporal integration time of the mammalian ear is 100 ms (as mentioned above). This approach is 

accurate at distances where the pulse duration is less than 100 ms, and conservative for longer distances. 

Most of the effects of these smaller sources occur at relatively short distances where the pulse durations 

are short so this approach is not expected to be overly conservative even for lower-level effects.

Conversion values for the larger airgun array source were determined with the Full-Waveform Rangedependent Acoustic Model (FWRAM) (JASCO Applied Sciences). This model was applied at a 

representative shallow (Shelf), mid-depth (Slope), and deep-water location along each of the three 

acoustic modeling transects (see Section 7.2.3.2). At each of these locations, the model was run along 16 

evenly spaced azimuths to examine the effect of source directivity and direction-dependent bathymetric 

variation. The synthetic data from the model were processed to compute SEL and rms SPL using 100 ms 

time windows. These results were computed as a function of distance, receiver depth, and receiver 

direction from each full-waveform modeling site. Conversion tables were then used to extract 

representative SEL to rms SPL conversions at all 30 sites modeled using MONM. The optimal conversion 

values were selected from the tables based on the closest full-waveform model source location and the 

nearest azimuthal direction, using bilinear interpolation over receiver range and depth. 

5.3. Animal Movement Modeling for Impact Assessment

The sounds animals receive when near one or more sound sources are a function of where the animal is at 

any given time relative to the source(s), which may themselves be moving (Figure 7). To a reasonable 

approximation, the location of the sound source(s) is known and acoustic modeling can be used to predict 

the three dimensional (3-D) sound field (Section 5.1 and 5.2). The location of animals within the sound 

field, however, is unknown. Realistic animal movement within the sound field can be simulated, and 

repeated random sampling (Monte Carlo)—achieved by simulating many animals within the operations 

area—used to estimate the sound exposure history of animals during the operation. Monte Carlo methods 

provide a heuristic approach to determine the probability distribution function (PDF) of complex 

situations, such as animals moving in a sound field. A greater number of random samples, in this case 

more simulated animals (animats), better approximates the PDF. Animats are randomly placed, or seeded, 

within the simulation boundary at a specified density (animats/km2

), and to maintain constant modeling 

density any animat exiting across a border is replaced with a new animat at the opposite border. Higher 

densities provide a finer PDF estimate resolution, but require greater computational resources. To ensure 

good representation of the PDF, the animat density is set as high as practical allowing for computation 

time. The resulting PDF is then scaled using the real-world animal density to obtain the real-world 

number of individuals affected. The probability of an event’s occurrence is determined by the frequency 
D-28 Acoustic Propagation and Marine Mammal Exposure Modeling

with which it occurs in the simulation. The Monte Carlo method works well for assessing the probability 

of common events, its weakness is in accurately determining the probability of rare events.

Several models for marine mammal movement have been developed (Ellison et al. 1987, Frankel et al. 

2002, Houser 2006). These models use an underlying Markov chain to transition from one state to another 

based on probabilities determined from measured swimming behavior. The parameters may represent 

simple states, such as the speed or heading of the animal, or complex states, such as likelihood of an 

animal foraging, playing, resting, or traveling. This analysis uses the Marine Mammal Movement and 

Behavior (3MB) model developed by (Houser 2006). The parameters used for forecasting realistic 

movement are detailed in Appendix C. 

Figure 7. Cartoon animats in a moving sound field. The acoustic exposure of each animat is determined 

by where it is in the sound field, and its exposure history is accumulated as the simulation 

progresses. In this cartoon, the vessel and sound source are moving right to left, as is the 

lowest animat. The two upper animats move from left to right. Because the upper and lower 

animats are far from the source, low levels of sound exposure are expected. The middle 

animat is nearer the sound source so its acoustic exposure would be expected to be higher 

than the other two animats, and its highest exposure occurs when it is closest to the sound 

sources at the second time step (t2). 

5.4. Acoustic Exposure Criteria 

The Marine Mammal Protection Act (MMPA 2007) defines harassment as any act of pursuit, torment, or 

annoyance that (i) has the potential to injure a marine mammal, or (ii) has the potential to disturb a marine 

mammal by disrupting its behavioral patterns, including but not limited to, migration, breathing, nursing, 

breeding, feeding, or sheltering. 

Harassment with the potential for injury is termed Level A harassment, and harassment with the potential 

to disrupt behavior is termed Level B harassment. Loud sounds can potentially damage the hearing of 

marine mammals or disrupt their behavior. In the 1990s, NMFS adopted received levels for pulsed sounds 

that should not be exceeded for marine mammals. The rms SPL thresholds for marine mammals exposed 

to impulsive sound are 180 dB re 1 μPa for Level A and 160 dB re 1 μPa for Level B (NMFS 1995, 

NMFS 2000). 
Gulf of Mexico G&G Activities Programmatic EIS D-29

These criteria were set before there was adequate data about the received levels that could injure marine 

mammals. Since then, more data have become available. In 1998, a group of experts was convened to 

update and establish methods for determining acoustic exposure criteria (Gentry et al. 2004). The results 

of the expert group were published as Southall et al. (2007) and are commonly referred to as the Southall 

criteria. In this report, the Southall criteria were used as the basis for developing additional exposure 

criteria to evaluate potential impacts of the modeling results described in this study. 

5.4.1. Marine Mammal Frequency Weighting Functions

The potential for anthropogenic sounds to impact marine animals depends on how well the animal detects 

the sounds. Sounds are less likely to injure or disturb animals if it occurs at frequencies that an animal 

cannot hear well, except when the sound pressure level is so high that it could physically injure tissue. 

Based on a review of marine mammal hearing and on physiological and behavioral responses to 

anthropogenic sounds, Southall et al. (2007) proposed standard frequency weighting functions—referred 

to as M-weighting functions—for three functional hearing groups of cetaceans (Table 1):

• Low-frequency cetaceans (LFCs)—mysticetes (baleen whales)

• Mid-frequency cetaceans (MFCs)—some odontocetes (toothed whales)

• High-frequency cetaceans (HFCs)—odontocetes specialized for using high-frequencies 

The discount applied by the M-weighting functions for less-audible frequencies is less than that indicated 

by the corresponding audiograms (where available) for member species of these hearing groups. The 

rationale for applying a smaller discount than suggested by the audiograms measured at low sound levels 

is due in part to an observed characteristic of mammalian hearing that, as sound levels increase, perceived 

equal loudness curves increasingly have less rapid roll-off outside of the most sensitive hearing frequency 

range. This is why, for example, C-weighting curves for humans, used for assessing loud sounds such as 

blasts, are flatter than A-weighting curves, used for quiet to mid-level sounds. The M-weighting functions 

are, therefore, usually applied at high sound levels where impacts such as temporary or permanent hearing 

threshold shifts might occur. The use of M-weighting is considered precautionary (in the sense of 

overestimating the potential for impact) when applied to lower level impacts such as the onset of 

behavioral response. Figure 8 shows the decibel frequency weighting of the cetacean underwater 

M-weighting functions. 

The M-weighting functions have unity gain (0 dB) through the passband and their high and low frequency 

roll-offs are approximately –12 dB per octave. The amplitude response in the frequency domain is defined 

by:

































+ 













 −= +

hi

low

f

f

f

f KfG

2

2

2

10 11log20)( (14) 

where K is a constant used to normalize the function at a reference frequency, and the roll-off and 

passband of these functions are controlled by the parameters flo and fhi, the estimated upper and lower 

hearing limits specific to each functional hearing group (Table 3). 
D-30 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 8. Standard M-weighting functions for the four underwater functional marine mammal hearing 

groups (Southall et al. 2007). 

Table 3. Low and high frequency cut-off parameters of M-weighting functions for the cetacean functional hearing 

groups (Southall et al. 2007). 

Functional hearing group K flow (Hz) fhi (Hz)

Low-frequency cetaceans 0 7  22,000

Mid-frequency cetaceans 0 150 160,000

High-frequency cetaceans 0 200 180,000

Subjective loudness measurements for a common bottlenose dolphins have provided information to help 

develop equal-loudness contours for this animal (Finneran and Schlundt 2011). Equal loudness contours 

(also called Fletcher-Munson curves) are the sound levels over the frequency spectrum for which a 

listener perceives constant loudness. These curves are the basis of the Occupational Safety and Health 

Administration (OSHA) noise regulation 1910.95. The equal-loudness contours determined by Finneran 

and Schlundt (2011) better match the frequency dependence of TTS onset data (Schlundt et al. 2000) than 

audiograms or the M-weighting curves. For this reason, the dolphin equal-loudness contours were used to 

develop marine mammal frequency weighting functions (Finneran and Jenkins 2012). 

The (inverse) equal-loudness contours were fit with equations of the same form as the M-weighting 

function (Equation 14). The fits suggest steeper roll-off at lower frequencies than the mid-frequency Mweighting curve. Because data for the equal-loudness contours did not cover the entire spectral range of 

the M-weighting functions, the M-weighting curves were modified. The lowest frequency for which 

subjective loudness data were obtained was 3 kHz, therefore Finneran and Jenkins (2012) took a 

conservative approach and set the mid-frequency M-weighting curve and the inverted equal loudness 

contour equal at 3 kHz. The result is that below 3 kHz the overall function is identical to the M-weighting 

curves, while above 3 kHz the overall function is equal to the fitted (inverse) equal-loudness contour. A 

similar procedure was used for low- and high-frequency animals, but the fitting parameters for the 

inverted equal-loudness contours were adjusted appropriately for each of those groups. 
Gulf of Mexico G&G Activities Programmatic EIS D-31

Frequency weighting functions for cetaceans are calculated as:

































+ 













 −= + 2

1

2

2

2

1

1 1 10 11log20)(

hi

low

f

f

f

f KfG (15) 

































+ 













 −= + 2

2

2

2

2

2

2 2 10 11log20)(

hi

low

f

f

f

f KfG (16) 

( ) max[ )](),( 2 1 2 = fGfGfG (17) 

where flow1 and fhi1 are the same parameter values for M-weighting, and flow 2 and fhi2 are the fitted 

parameters for the inverted equal-loudness contour adjusted for hearing groups. K2 is used to normalize 

the G2 equation to zero at 10 kHz (the reference frequency for the subjective loudness studies) and K1 is 

used to set the G1 equation equal to the G2 equation at 3 kHz for mid-frequency and high-frequency 

species. For low-frequency species, K1 was adjusted so that the flat portion of the G2 was 16.5 dB below 

the peak level of G2 (as it was for the mid-frequency cetaceans). G1 and G2 are equal at 267 Hz for lowfrequency species. Parameters for each of the cetacean groups are shown in Table 4, and the resulting 

frequency weight curves are shown in Figure 9. 

Finneran and Jenkins (2012) termed their frequency weighting functions Type II M-weighting and 

referred to the original Southall et al. (2007) M-weighting as Type I M-weighting. We adopt the Finneran 

and Jenkins (2012) nomenclature in this study. 

Table 4. Frequency weighting parameters for the cetacean functional hearing groups. Modified from Finneran and 

Jenkins (2012). 

Functional hearing group K1

(dB)

flow1

(Hz)

fhi1

(Hz)

K2

(dB)

flow2

(Hz)

fhi2

(Hz)

Inflection point 

(Hz)

Low-frequency cetaceans −16.5 7  22,000 0.9 674  12,130  267

Mid-frequency cetaceans −16.5 150 160,000 1.4 7,829  95,520 3,000

High-frequency cetaceans −19.4 200 180,000 1.4 9,480 108,820 3,000
D-32 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 9. Frequency weighting functions for the cetacean functional hearing groups. Adapted from 

Finneran and Jenkins (2012). 

5.4.2. Injury Exposure Criteria Selection

Loud or sustained sounds can injure an animal’s hearing structures, resulting in a permanent shift in 

hearing thresholds (PTS; see Section 3.4.3). There are no data on the sound levels that cause PTS in 

marine mammals. There are, however, data that indicate the received sound levels at which temporary 

threshold shifts (TTS) occur. PTS onset can be hypothetically extrapolated from TTS onset and growth. 

Sound level and duration are key determinants in TTS. The SEL metric includes amplitude, duration, and 

TTS magnitude. TTS is best correlated with SEL (rather than SPL) in dolphins exposed to sounds of < 8 s 

long (Finneran et al. 2005). Although limited, these findings are consistent with an equal acoustic energy 

hypothesis for TTS prediction (see Southall et al. 2007). Data from terrestrial mammals indicate that TTS 

of 40–50 dB could be induced without causing PTS (e.g., Ward et al. 1958, Ward et al. 1959, Ward 1960, 

Miller 1963, Kryter et al. 1966). Southall et al. (2007) chose 40 dB of TTS as a conservative onset limit 

of PTS. In humans, Ward et al. (1958) found a linear relationship between TTS and SEL of 1.5–1.6 dB 

TTS per 1 dB increase in SEL. TTS onset is defined as the sound level that produces 6 dB of TTS. The 

TTS growth rates from Ward et al. (1958) predict the onset PTS SEL at about 21 dB greater than the 

onset of TTS SEL (34/1.6 ≈ 21). This TTS growth rate appears to be conservative for cetaceans, as 

Finneran and Schlundt (2010) measured a TTS growth rate in a dolphin exposed to 16 s tones from 3 and 

20 kHz, to be somewhat less than the values found in humans by Ward et al. (1958). For non-pulsed 

stimuli, both Southall et al. (2007) and Finneran and Jenkins (2012) rounded down and used a 

conservative value of 20 dB + TTS SEL onset as the PTS SEL onset level. For pulsed sounds, Henderson 

and Hamernik (1986) reported that the TTS growth rate for chinchillas was between 0.5 and 3 dB TTS 

per dB SEL, with higher growth rates at higher SELs. Southall et al. (2007) used 2.3 dB TTS per dB SEL 

as a conservative growth rate to predict PTS SEL onset for marine mammals, and thus calculated 15 dB + 

TTS SEL onset as the PTS SEL onset. Because TTS is related to hearing sensitivity, the signal levels for 

determining TTS and PTS should be filtered using an appropriate auditory frequency weighting function 

(see Section 5.4.1). 
Gulf of Mexico G&G Activities Programmatic EIS D-33

Particularly loud sounds could induce TTS regardless of whether a cumulative sound energy (SEL) 

threshold has been exceeded or how long they last. Rather than the sensory system fatiguing, tissue 

damage might occur, which would violate the equal-energy assumption of TTS prediction. In this case, 

SPL is the appropriate metric and no auditory frequency weighting is applied. In assessing the potential 

for injury due to these sounds, Southall et al. (2007) began with 40 dB of TTS as the onset of PTS. They 

used a conservative extrapolation of chinchilla data to argue that sounds 6 dB above the TTS SPL 

threshold could cause PTS. 

Injury exposure criteria for each cetacean functional hearing group is determined from TTS onset data as 

explained below, and the results are shown in Table 5. 

Low-Frequency Cetaceans

There are no TTS data for low-frequency species. As a conservative measure, the Type I M-weighting 

function described by Southall et al. (2007; Section 5.4.1) was used for low-frequency species. 

Extrapolating current data from mid-frequency animals, we subtracted 6 dB from the Southall et al. 

(2007) SEL injury criteria of 198 dB re 1 μPa2

·s to obtain 192 dB re 1 μPa2·s for use in this study (Wood 

et al. 2012). 

Mid-Frequency Cetaceans 

For pulsed sounds, TTS data are available for common bottlenose dolphins and beluga whales exposed to 

single impulse from a seismic watergun (Finneran et al. 2002). The beluga whales were found to have a 

TTS onset at a SEL of 186 dB re 1 μPa2

·s or peak SPL of 224 dB re 1 μPa (measured at 0.4 and 30 kHz). 

The dolphins showed no TTS up to a SEL of 186 dB re 1 μPa2

·s or peak SPL of 226 dB re 1 μPa. As a 

precaution, the TTS onset levels for the beluga are taken to represent all mid-frequency cetaceans 

(Southall et al. 2007, Finneran and Jenkins 2012). Using the auditory frequency weighting, TTS onset 

occurs at an SEL of 172 dB 1 μPa2

·s. Adding 15 dB results in a PTS SEL threshold of 187 dB 1 μPa2·s. 

We used the unweighted peak SPL of 224 dB re 1 μPa for TTS in beluga to predict PTS onset for 

particularly loud sounds that violate the equal energy hypothesis for TTS prediction (Southall et al. 2007, 

Finneran and Jenkins 2012). Adding 6 dB to the TTS onset results in a PTS SPL onset threshold of 

230 dB re 1 μPa. We used this hypothetical exposure value as SPL PTS threshold for all mid-frequency 

cetaceans and for all types of sounds. 

High-Frequency Cetaceans 

Lucke et al. (2009) found a TTS SEL onset of 164 dB re 1 μPa2

·s at 4 kHz for a harbor porpoise exposed 

to a seismic airgun impulse. When auditory frequency weighting is applied to the airgun signal, the SEL 

TTS exposure threshold is 146 dB re 1 μPa2

·s (see Finneran and Jenkins 2012); adding 15 dB to the TTS 

onset results in an SEL threshold of 161 dB re 1 μPa2

·s as the PTS exposure criteria for pulsed sounds. 

Lucke et al. (2009) also found that 194 dB re 1 μPa was the peak SPL that resulted in TTS. Adding 6 dB 

to the peak SPL results in a peak SPL PTS onset of 200 dB re 1 μPa, which will be used in this report as 

the peak sound pressure level exposure criteria for high-frequency cetaceans for all types of sounds. 
D-34 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 5. Injury exposure criteria for pulsed sounds. Cumulative sound exposure level (SEL) is weighted for hearing 

sensitivity; peak sound pressure level (peak SPL) is unweighted.

Functional hearing group SEL

(dB re 1 μPa2·s)

peak SPL

(dB re 1 μPa)

Low-frequency cetaceans 192 230

Mid-frequency cetaceans 187 230

High-frequency cetaceans 161 200

5.4.3. Behavioral Exposure Criteria Selection

NMFS currently uses a step function at an unweighted rms SPL of 160 dB re 1 μPa to assess behavioral 

impacts (NMFS and NOAA1995). This threshold is based on observations of migrating mysticete whales 

responding to an airgun (Malme et al. 1984, Malme et al. 1988). Although animals’ behaviors in response 

to sounds might happen at lower levels, significant responses were only likely to occur above an rms SPL 

of 140 dB re 1 μPa; animals began avoiding pulsed sounds when rms SPL neared 160 dB re 1 μPa 

(Malme et al. 1988). 

Southall et al. (2007, Appendix B) extensively reviews behavioral responses to sounds, and finds that 

most marine mammals exhibited varying responses between rms SPLs of 140 and 180 dB re 1 μPa—

consistent with the NMFS threshold—but lack of convergence in the data prevents them from suggesting 

explicit step functions. Lack of controls, precise measurements, appropriate metrics, and context 

dependency of responses (including the activity state of the animal) all contribute to variability. Southall 

et al. (2007) propose a severity scale that increases with increased sound level as a qualitative scaling 

paradigm. 

For pulsed sounds, Wood et al. (2012) proposed a graded probability of response with 10% response 

likelihood at an rms SPL of 140 dB re 1 μPa, 50% at an rms SPL of 160 dB re 1 μPa, and 90% at an rms 

SPL of 180 dB re 1 μPa for most marine mammals. Wood et al. (2012) also designated behavioral 

response categories for migrating mysticetes and sensitive species, such as harbor porpoises and beaked 

whales. For the sensitive species, the likelihood of a 50% response was set to an rms SPL of 120 dB re 

1 μPa; 90% response probability was set at an rms SPL of 140 dB re 1 μPa (Wood et al. 2012). No 

migrating mysticetes were modeled in our study. 

The NMFS step function, (unweighted) rms SPL of 160 dB re 1 μPa, and the Wood et al. (2012) graded 

functions (Table 6) were used to determine the number of behavioral responses. Following Wood et al. 

(2012), Type I weighting was used to filter the source signals when behavioral responses were evaluated 

with the graded functions (see Section 5.4.1). 

Table 6. Behavioral exposure criteria. Probability of behavioral response frequency-weighted sound pressure level 

(rms SPL dB re 1 μPa). Probabilities are not additive. Adapted from Wood et al. (2012). 

Marine mammal group 

Probability of response to frequency-weighted rms SPL

(dB re 1 μPa)

120 140 160 180

Beaked whales 50% 90%

All other species 10% 50% 90%
Gulf of Mexico G&G Activities Programmatic EIS D-35

5.4.4. Exposure Estimation 

5.4.4.1. Injury Exposure Estimates—cumulative SEL

To evaluate the likelihood an animal might be injured from accumulated sound energy, the cumulative 

SEL for each animat in the simulation was calculated. To obtain that animat’s cumulative SEL, the SEL 

an animat received from each source over the integration window was summed. The number of animats 

whose cumulative SEL exceeded the specified thresholds (Table 5) during the integration window was 

counted. 

5.4.4.2. Injury Exposure Estimates—peak SPL

To evaluate the likelihood an animal might be injured by being exposed to peak SPL, we estimated the 

range at which the specific peak SPL threshold occurs (Table 5) for each source based on the broadband 

peak SPL source level. For each integration window, the number of animats that came within this range 

of the source was counted. 

5.4.4.3. Behavior Exposure Estimates—rms SPL

To evaluate the likelihood an animal might have its behavior disrupted based on the step function criteria, 

we calculated the number of animats that received a maximum rms SPL exposure within the specified 

step ranges (Table 6). The number of animats with a maximum rms SPL received level categorized into 

each bin of the step function was scaled by the probability of the behavioral response specific to that 

range (Table 6). These scaled values were then summed as the estimated number of behavioral exposures. 

This process was repeated for each integration window. 

5.4.4.4. NMFS Criteria for Injury and Behavior Exposure Estimates—rms SPL

To evaluate the likelihood an animal might be injured or its behavior disrupted based on NMFS’s criteria 

(180 and 160 dB rms SPL, respectively), we set the exposure simulation to use un-weighted rms SPL 

acoustic fields. The number of animats receiving an exposure greater than 180 dB was counted as the 

number of injurious exposures. The number of animats that received an exposure between 160 dB and 

180 dB was counted as the number of behavioral exposures. An animat counted as an injurious exposure 

is not counted as a behavioral disruption exposure. As with the other criteria, animat received level was 

reset at the beginning of each integration window. 
D-36 Acoustic Propagation and Marine Mammal Exposure Modeling

6. Phase I: Test Case and Test Scenarios 

A seismic survey Test Case was defined and evaluated using acoustic and animal movement models as an 

initial evaluation of potential impacts on marine mammals and to establish the use of various modeling 

methodologies prior to the Phase II modeling. The Test Case was a typical WAZ seismic survey 

conducted at two locations near the Mississippi Canyon of the Gulf of Mexico (Figure 10). Survey site A 

was centered on the slope of the continental shelf break and Survey site B was centered on the deep ocean 

plain. The WAZ surveys consisted of four vessels sailing in parallel with staggered sail directions. Each 

vessel towed two 8000 in3 arrays. Six species (Bryde’s whales, Cuvier’s beaked whales, common 

bottlenose dolphins, dwarf sperm whales, short-finned pilot whales, and sperm whales) were evaluated in 

the Test Case as representative Gulf of Mexico species that may be near the survey sites. Bryde’s whales 

were chosen because they are the only low-frequency species in the Gulf. Dwarf sperm whales were 

chosen as the representative high-frequency Kogia species. The four mid-frequency species were chosen 

to represent various other aspects of diving and hearing sensitivity. Cuvier’s beaked whales are deepdiving and behaviorally sensitive to sounds, sperm whales are also deep-diving and are the only 

endangered species listed in the Gulf. Short-fin pilot whales and common bottlenose dolphins both 

represent the swimming behavior of smaller cetaceans with different preferred water depth. Sound 

exposure estimates were determined by first using computational models to calculate sound fields 

generated by the airgun arrays, and then by sampling those sound fields using computational models of 

animal movement during each survey. Risk for each species was evaluated based on the predetermined 

exposure criteria (see Section 5.4).
Gulf of Mexico G&G Activities Programmatic EIS D-37

Figure 10. Locations of the Survey site A (purple box) and Survey site B (red box) and acoustic field 

modeling sites. 

6.1. Test Case Acoustic Source Parameters

The WAZ surveys consist of four vessels, each towing two 8000 in3 airgun arrays fired in flip-flop mode 

with a shot interval of ~ 14 s. 

Acoustic source levels were modeled for the Bolt 1900 LLXT 8000 in3 airgun array, which was used for 

the 3-D WAZ survey. The array consisted of six sub-arrays with 9 m in-line separations. The airguns fired 

simultaneously at 2,000 psi air pressure. The airgun array was modeled at a tow depth of 8 m (the center 

of the array). Table 7 describes the horizontal layout of each sub-array. Figure 11 presents the airgun 

distribution in the horizontal plane and gives the volume of each airgun within the sub-array. 
D-38 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 7. Relative airgun positions within each of the six sub-arrays. The center of each sub-array is aligned at the 

same position in x (fore-aft, where the array is towed in the positive x direction), and spaced 9 m apart in y (portstarboard, where port is in the positive y direction). All airguns are at 8 m depth. The volume of the airgun at each 

position varies among the sub-arrays.

Gun x (m) y (m)

Volume (in3)

Strings 1 and 6 Strings 2–5 

1 −7.0 0.4 150 150

2 −7.0 −0.4 150 150

3 −4.0 0.4 70 60

4 −4.0 −0.4 70 60

5 −2.0 0 50 40

6 0.0 0 90 70

7 2.0 0.4 70 60

8 2.0 −0.4 70 60

9 4.0 0.4 60 90

10 4.0 −0.4 60 90

11 7.0 0.4 250 250

12 7.0 −0.4 250 250
Gulf of Mexico G&G Activities Programmatic EIS D-39

Figure 11. Layout of the modeled airgun array (8000 in3 total firing volume, 8 m depth), which is 

composed of 6 sub-arrays of 12 airguns each (72 airguns in total). The relative size of green 

circles and the numbers next to each indicate airgun firing volume. 
D-40 Acoustic Propagation and Marine Mammal Exposure Modeling

6.2. Test Case Environmental Parameters

6.2.1. Modeling Sites

Survey site A and Survey site B around Mississippi Canyon (rectangular zones in Figure 10) were

selected to be representative of locations for typical shallow (Survey site A) and deep (Survey site B) 3-D 

wide azimuth surveys conducted in the Gulf. Survey site A was placed so that the shallowest portion 

would remain at a depth of at least ~ 100 m to ensure that the survey could be safely conducted. The 

location for Survey site B was chosen to include the deepest water where a seismic survey could 

reasonably be expected to occur. Acoustic fields were computed at four locations in each survey area

(Figure 10), with one location common to both areas. As examples, Appendix A shows per-pulse acoustic 

fields from a single 8000 in3 array as field maps and tables of propagation radii for three of the acoustic 

propagation modeling sites. 

6.2.2. Bathymetry

Water depths throughout the modeled area were obtained from the National Geophysical Data Center’s 

U.S. Coastal Relief Model (NGDC 2003) that extends up to about 200 km from the U.S. coast. These 

bathymetry data have a resolution of 3 arc-seconds (~ 80 × 90 m at the studied latitude). Bathymetry data 

for an area were extracted and re-gridded, using minimum curvature method, onto a Universal Transverse 

Mercator (UTM) zone 15 coordinate projection with a horizontal resolution of 50 × 50 m. 

6.2.3. Multi-Layer Geoacoustic Profile

MONM assumes a single geoacoustic profile of the seafloor for the entire modeled area. MONM requires 

these acoustic properties: 

• Sediment density

• Compressional-wave (or P-wave) speed

• P-wave attenuation in decibels per wavelength

• Shear-wave (or S-wave) speed

• S-wave attenuation, also in decibels per wavelength

The geoacoustic parameters were estimated based on typical values expected within the Mississippi 

Canyon, in accordance with our experience in modeling this area. Survey site A was in the vicinity of 

latitude 28 N and longitude 89 W, and Survey site B was centered approximately 72 km farther southeast 

(Figure 10). Modeling at Survey site A required two geoacoustic provinces, one consisting of surficial 

clay, designated S01, and a second consisting of surficial sand, designated S02. Modeling at Survey site B 

required only one geoacoustic province, designated as D01. The geoacoustic profile assumed for these 

three modeling provinces is shown in Tables 8 through 10, respectively.
Gulf of Mexico G&G Activities Programmatic EIS D-41

Table 8. Geoacoustic properties of the sub-bottom sediments as a function of depth for the S01 modeling province.

Within each depth range, each parameter varies linearly within the stated range.

Depth 

below 

seafloor 

(m)

Material Density 

(g/cm3) 

P-wave speed 

(m/s)

P-wave 

attenuation 

(dB/λ)

S-wave speed 

(m/s)

S-wave 

attenuation

(dB/λ)

0–10

Clay

1.44–1.61 1480–1522 0.21–0.37

100 0.1

10–50 1.61–1.78 1522–1610 0.37–0.56

50–100 1.78–1.87 1610–1670 0.56–0.67

100–300 1.87–2.0 1670–1800 0.67–0.9

300–1000

Compacted/ 

consolidated 

sediments

2.0–2.5 1800–3000 0.9–0.2

> 1000

Compacted/ 

consolidated 

sediments

2.5 3000 0.2

Table 9. Geoacoustic properties of the sub-bottom sediments as a function of depth for the S02 modeling province.

Within each depth range, each parameter varies linearly within the stated range.

Depth 

below 

seafloor 

(m)

Material Density 

(g/cm3) 

P-wave speed 

(m/s)

P-wave 

attenuation 

(dB/λ)

S-wave speed 

(m/s)

S-wave 

attenuation 

(dB/λ)

0–10

Silt

1.44–1.61 1505–1570 0.34–0.55

150 0.2

10–50 1.61–1.78 1570–1695 0.55–0.86

50–100 1.78–1.87 1695–1775 0.86–1.02

100–300 1.87–2.0 1775–1950 1.02–1.3

300–1000

Compacted/ 

consolidated 

sediments

2.0–2.5 1950–3000 1.3–0.2

> 1000

Compacted/ 

consolidated 

sediments

2.5 3000 0.2
D-42 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 10. Geoacoustic properties of the sub-bottom sediments as a function of depth for the D01 modeling province.

Within each depth range, each parameter varies linearly within the stated range.

Depth 

below 

seafloor 

(m)

Material Density 

(g/cm3) 

P-wave speed 

(m/s)

P-wave 

attenuation 

(dB/λ)

S-wave speed 

(m/s)

S-wave 

attenuation 

(dB/λ)

0–12 Soft clay 1.35–1.68 1460–1518 0.14–0.55

100 0.1

12–45 Clay 1.68–1.87 1518–1601 0.55–0.86

45–90

Stiff clay

1.87–1.95 1601–1660 0.86–1.02

90–200 1.95–2.0 1660–2200 1.02–1.3

200–1000

Compacted/ 

consolidated 

sediments

2.0–2.5 2200–3000 1.3–0.2

> 1000

Compacted/ 

consolidated 

sediments

2.5 3000 0.2

6.2.4. Sound Speed Profile

The sound speed profiles for the modeled sites were derived from temperature and salinity profiles from 

the U.S. Naval Oceanographic Office’s Generalized Digital Environmental Model V 3.0 (GDEM; Teague 

et al. 1990, Carnes 2009). GDEM provides an ocean climatology of temperature and salinity for the 

world’s oceans on a latitude-longitude grid with 0.25° resolution, with a temporal resolution of one 

month, based on global historical observations from the U.S. Navy’s Master Oceanographic 

Observational Data Set (MOODS). The climatology profiles include 78 fixed depth points to a maximum 

depth of 6800 m (where the ocean is that deep), including 55 standard depths between 0 and 2000 m. The 

GDEM temperature-salinity profiles were converted to sound speed profiles according to the equations of 

Coppens (1981): 

( )( )

[ ( )]

10

0026.01 cos 2

1000

18.03.16

009.0126.0333.1 35

23.021.57.4505.1449),,,(

2

2

2 3

T

t

z Z

ZZ

Stt

STzc ttt

=

−= φ

+=∆

+−+ ∆+−

−−+=φ

(18) 

where z is water depth (m), T is water temperature (°C), S is salinity (psu), and φ is latitude (radians). 

The sound speed profile for August at Survey site A indicates a strong, downward-refracting environment 

with a very weak surface sound channel (Figure 12). The surface channel is essentially absent in the 

Survey site B profile, which is also strongly downward refracting for a sound source near the surface. For 

a source near the surface, long-range acoustic propagation at both sites is mainly dependent on bottominteracting pathways (despite a weak surface channel at Survey site A). As discussed in Section 6.2.3, the 

bottom composition is unfavorable for long-range propagation. 
Gulf of Mexico G&G Activities Programmatic EIS D-43

Figure 12. Sound speed profiles for August in the Mississippi Canyon, Gulf of Mexico at Survey sites A 

and B, derived from data obtained from GDEM V 3.0 (Teague et al. 1990, Carnes 2009). 

6.2.5. Marine Mammals Density Estimates

Density estimates, animals/km2, for marine mammal species from survey data can be obtained from the 

online Strategic Environmental Research and Development Program (SERDP) Spatial Decision Support 

System (SDSS) hosted by Ocean Biogeographic Information System Spatial Ecological Analysis of 

Megavertebrate Populations (OBIS SEAMAP) at Duke University. For the Gulf of Mexico, the U.S. 

Navy OPAREA Density Estimate (NODE; DoN 2007) model is available. The NODE data for the Gulf of 

Mexico are based on shipboard surveys conducted between 1994 and 2004 by the National Marine 

Fisheries Service-Southeast Fisheries Science Center (NMFS-SEFSC). Surveys conducted before 2003 

were in conjunction with Southeast Area Monitoring and Assessment Program (SEAMAP) as adjuncts to 

cruises designed as ichthyoplankton sampling surveys. The NODE database generates seasonal density 

estimates for each species based on a statistical analysis of the survey data. For species with adequate 

sighting data, the DISTANCE model (Buckland et al. 2001) was used to generate density estimates. For 

species with too few sightings for the DISTANCE model to create a density, NOAA’s stock assessment 

report (SAR; Waring et al. 2013) data were used to generate density by dividing abundance by the 

regional area. 
D-44 Acoustic Propagation and Marine Mammal Exposure Modeling

Seasons were defined by the mean sea surface temperature (DoN 2007) as: 

• Winter: 23 Dec through 2 Apr 

• Spring: 3 Apr through 1 Jul 

• Summer: 2 Jul through 28 Sep

• Fall: 29 Sep through 22 Dec 

The DISTANCE model is a regression model (as opposed to a habitat suitability model), and, as with any 

model, a number of assumptions and simplifications are required. A notable assumption when generating 

the NODE database was that the estimating bias—the probability of detecting an object on a transect line, 

g(0)—was set to 1. That is, no correction is made to the density estimates to account for animals missed 

during the survey. Animals can be missed for a variety of reasons, including deep or long diving times for 

species including sperm whales and beaked whales. With no correction for the estimation bias, the density 

estimates should be regarded as floor estimates. Figures 13 and 14 are examples of density estimates for 

sperm whales obtained at Survey sites A and B, respectively. Tables 11 and 12 list the marine mammal 

density estimates for the species evaluated. The minimum, maximum, and mean density estimates for the 

region of interest are shown. 

Figure 13. Density estimates for sperm whales near Survey site A in the Gulf of Mexico from NODES 

model. Density is animals/km2

. The red rectangle represents the area around the survey site 

for which density estimates were obtained. 
Gulf of Mexico G&G Activities Programmatic EIS D-45

Figure 14. Density estimates for sperm whales near Survey site B in the Gulf of Mexico from NODES 

model. Density is animals/km2

. The red rectangle represents the area around the survey site 

for which density estimates were obtained. 

Table 11. Summer regional statistics of marine mammal density near Survey site A for the Gulf of Mexico. 

Common name

Regional Density (animals/km2)

Minimum Maximum Mean

Bryde’s whales 0 0.000105 0.000081

Cuvier’s beaked whales 0.000003 0.004121 0.000676

Common bottlenose dolphins† 0 0.107 0.01387

Short-finned pilot whales† 0 0.006277 0.004845

Sperm whales† 0.000036 0.008154 0.002761

Dwarf sperm whales 0 0.004605 0.000673

† Density estimates from SERDP-SDSS NODES database derived from NMFS-SEFSC survey data.

Table 12. Summer regional statistics of marine mammal density near Survey site B for the Gulf of Mexico. 

Common name

Regional Density (animals/km2)

Minimum Maximum Mean

Bryde’s whales 0 0.000105 0.000097

Cuvier’s beaked whales 0 0.004121 0.000809

Common bottlenose dolphins† 0 0.08429 0.001525

Short-finned pilot whales† 0 0.006277 0.005785

Sperm whales† 0.000365 0.005395 0.002311

Dwarf sperm whales 0.000002 0.01558 0.001589

† Density estimates from SERDP-SDSS NODES database derived from NMFS-SEFSC survey data.
D-46 Acoustic Propagation and Marine Mammal Exposure Modeling

6.2.6. Animal Movement Modeling

In in Phase I analysis, the Marine Mammal Movement and Behavior (3MB) model developed by Houser 

(2006) was used. 3MB is included in the Effects of Sound on the Marine Environment (ESME) interface 

developed by the Office of Naval Research (ONR) and Boston University (Gisiner et al. 2006, Shyu and 

Hillison 2006). ESME is an open-source software program conveniently combines animal movement 

models and computed sound fields. For the current application, ESME was modified so that it used the 

sound fields from the study area. 3MB uses a number of parameters to simulate realistic animal 

movement. It was necessary to determine these parameters from published studies for the simulated

species (see Appendix D).

6.3. Test Case Results

6.3.1. Acoustic Sources: Levels and Directivity

The pressure signatures of the individual airguns and the composite 1/3-octave-band source levels of the 

array, as functions of azimuthal angle (in the horizontal plan), were computed with AASM as described in 

Section 5.1. While effects of source depth on bubble interactions are accounted for in the AASM source 

model, the surface-reflected signal (i.e., surface ghost) is not included in the far-field source signatures. 

The surface reflections, a property of the medium rather than the source, are accounted for by the acoustic 

propagation models. 

6.3.1.1. 8000 in3 Airgun Array

The horizontal overpressure signatures and corresponding power spectrum levels for the 8000 in3 array, 

when stationary at a depth of 8 m (to the vertical center of the gun clusters), are shown in Figure 15 and 

Table 13 for the broadside (perpendicular to the tow direction) and endfire (parallel to the tow direction) 

directions. The signatures consist of a strong primary peak related to the initial firing of the airguns, 

followed by a series of pulses associated with bubble oscillations. Most energy is produced at frequencies 

below 200 Hz (Figure 15b). The spectrum contains peaks and nulls resulting from interference among 

airguns in the array, where the frequencies at which they occur depend on the volumes of the airguns and 

their locations within the array. The maximum (horizontal) 1/3-octave-band sound levels over all 

directions are plotted in Figure 16. The horizontal 1/3-octave-band directivities are shown in Figure 17. 

(a) (b) 

Figure 15. The 8000 in3 array: Predicted (a) overpressure signature and (b) power spectrum in the 

broadside and endfire (horizontal) directions. Surface ghosts (effects of the pulse reflection at 
Gulf of Mexico G&G Activities Programmatic EIS D-47

the water surface) are not included in these signatures as they are accounted for by the 

MONM propagation model. 

Table 13. Horizontal source level specifications (10–5000 Hz) for the seismic airgun array (8000 in3) at 8 m depth, 

computed with AASM in the broadside and endfire directions. Surface ghost effects are not included as they are 

accounted for by the MONM propagation model.

Direction Zero-to-peak SPL 

(dB re 1 μPa @ 1 m)

SEL (dB re 1 μPa2 @ 1 m)

0.01–2 kHz 0.01–1 kHz 1–2 kHz

Broadside 248.1 225.7 225.7 182.2

Endfire 255.2 231.8 231.8 189.6

Figure 16. Maximum directional source level (SL) in the horizontal plane, in each 1/3-octave-band, for 

the 8000 in3 airgun array (10–5000 Hz). 
D-48 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 17. Horizontal directivity of the 8000 in3 array. Source levels (SLs, dB re 1 μPa2

·s) in 

1/3-octave-bands. The 1/3-octave-band center frequencies are indicated above each plot.
Gulf of Mexico G&G Activities Programmatic EIS D-49

6.3.1.2. Per-Pulse Acoustic Field for Input to ESME

The per-pulse acoustic field propagation modeling for input to ESME was computed for the Survey site A 

and Survey site B modeling locations. Transmission loss for the purpose of exposure simulation was 

modeled along 16 radial profiles (angular step 22.5°) to the range of up to 50 km from the source location. 

The horizontal step along the radials was 10 m. At each surface sampling location, the sound field was 

sampled at multiple depths with equal vertical steps of 10 m down to the maximum water depth along the 

profile. 

The frequencies up to 5 kHz for the airgun array source were considered in the calculations of the 

broadband received levels. All 1/3-octave-band frequencies from 10 Hz to 5 kHz were used for the airgun 

array source level modeling (Section 7.3.1). For the transmission loss calculations, frequencies higher 

than 2 kHz are computationally intensive, so it was assumed that the transmission loss field for higher 

frequencies (up to 5 kHz) was identical to that at 2 kHz.

The broadband acoustic field passed as input to ESME was in SEL metrics and was both range and depth 

dependent (Figure 18).

Figure 18. An example of per-pulse received SEL field (with mid-frequency cetacean auditory frequency 

weighting applied) from the 8000 in3 airgun array at the S01 modeling province. 

6.3.1.3. Range to Zero-to-Peak SPL Isopleths

To evaluate the risk of acoustic injury, the range to the unweighted, zero-to-peak SPL (dB re 1μPa) was 

needed to the 200 dB isopleth (high-frequency cetaceans) and 230 dB isopleth (low- and mid-frequency 

cetaceans). The ranges were calculated assuming spherical spreading from a point source starting with the 

maximum source level of the airgun arrays being considered. The maximum zero-to-peak source level for 

the 8000 in3 array was 255.2 dB re 1μPa in the endfire direction (Table 13; the broadside source level was 

lower). The range to 200 dB zero-to-peak SPL re 1μPa was 575.4 m and the range to 230 dB zero-to-peak 

SPL re 1μPa was 18.2 m. The source level of the array is a theoretical definition assuming a point source 

and measurement in the far field of the source. The 230 dB isopleth was within the near field of the array 

where the definition of source level breaks down, so actual locations within the 18.2 m of the array center 
D-50 Acoustic Propagation and Marine Mammal Exposure Modeling

(or near any one airgun) where the sound level exceeds 230 dB zero-to-peak SPL re 1μPa did not 

necessarily exist. The 200 dB isopleth, however, was in the far field and sound levels within 575.4 m of 

the center of the array did experience sound levels exceeding 200 dB zero-to-peak SPL re 1μPa. The 

number of animals expected to come within the 200 dB and 230 dB isopleths were determined for the 

high-frequency, and low-frequency and mid-frequency cetaceans, respectively. 

6.3.2. Simulation Exposure Estimates

The amount of acoustic energy received depends on where in the sound field, both horizontally and 

vertically, an animal is when the sound source is active. Animal movement was simulated using the 

Marine Mammal Movement and Behavior (3MB) model, and ESME was used to sample the sound field 

produced by the airgun array. Sampling the sound field(s) produced during an operation using a simulated 

animal (animat) provided a history of acoustic exposure for that animat. The acoustic exposure history of 

many animats yields the probability, or risk, of exposure due to operations. 

Two sites were chosen near the Mississippi Canyon to conduct hypothetical, though typical, WAZ 

surveys. Survey site A was centered on the slope of the continental shelf break with the survey extending 

into shallow waters on the continental shelf. Survey site B was centered in deeper water though the survey 

also included the slope of the continental shelf break. The longitudinal tow direction of the vessels was 

selected for computational efficiency. 

The WAZ survey area was covered in a racetrack fashion using four seismic vessels, each towing a single 

airgun array. Production segments were 100 km long and the overall survey width was 60 km. Each 

production segment included 5 km run-in and run-off segments, and the turning segment to the next track 

line in the opposite direction was 30 km. For the first vessel, the lateral offset to the track in the opposite 

direction was 30 km. The other vessels had identical track geometries, but laterally shifted by 350 m 

relative to their neighbors. There was also a 2700 m shift along the track for each vessel, so the vessels 

were not moving side-by-side (inset Figure 19). Each vessel delivered a seismic pulse every 60 s (15 s for 

the vessel group), and vessel speed was 4 kts.

To account for variability of sound propagation due to changing water depth, the acoustic field was precomputed at four locations for each of the survey areas. For each location, the 2-D acoustic field was 

calculated for 16 radials emanating from the source (airgun array). For each shot during the simulation, an 

acoustic field was selected from the pre-computed set based on the nearest neighborhood method. 

To evaluate potential behavioral response, 30 day simulations of hypothetical WAZ surveys (Survey 

sites A and B) were run for each of the species evaluated (Figure 19). The boundaries of the simulation 

were determined from transmission loss calculations by finding the maximum range at which an animat 

could receive an rms SPL ≥ 120 dB re 1μPa (the lowest exposure levels at which impacts are expected). 

The maximum range was estimated at 50 km. To evaluate potential behavioral disruption, the simulation 

area was defined based on the perimeter of the survey tracks with an extension of 50 km on each side with 

the exception for the north side at Survey site A, where the extension was 35 km due to proximity of the 

shore. The simulation areas for Survey sites A and B were 214 × 144 km (30,800 km2

) and \212 × 161 km 

(34,100 km2

), respectively. To evaluate potential injury, the width of the survey was reduced to 11 km 

(Figure 20), and duration of 5 days. The boundaries of the simulation were extended by 5 km on each side 

of the survey area for 214 × 21 km (5061 km2

) areas at both Survey site A and Survey site B (Figure 20). 

The animat density for simulations were 0.1 and 2 animats/km2

 for behavior and injury, respectively. 

Exposure levels were determined for the combined effect of the sources. Results for each of the marine 

mammal species are shown in Table 14 for Survey site A and Table 15 for Survey site B. Appendix A

shows the frequency of exposure level for each simulation. 
Gulf of Mexico G&G Activities Programmatic EIS D-51

Figure 19. Vessel track locations for behavioral response analysis at Survey sites A and B. Inset shows 

the starting point in the southeast corner. 
D-52 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 20. Vessel track locations for injury analysis at Survey sites A and B. Inset shows the starting 

point in the southeast corner. 
Gulf of Mexico G&G Activities Programmatic EIS D-53

Table 14. Number of modeled cetaceans above exposure criteria for Survey site A for entire duration of the 

simulations. Simulations for zero-to-peak SPL and SEL injury metrics were 5 day duration with animat density of 

2.0 animats/km2

. Simulations for rms SPL metrics were 30 day duration with animat density of 0.1 animats/km2. 

Marine mammal species

Injury Behavior

zero-topeak SPL SEL 180 dB 

rms SPL

160 dB 

rms SPL

Step fxn. 

rms SPL

Bryde’s whales 47 534 348 571 637

Cuvier’s beaked whales 45 0 276 577 1941.4

Common bottlenose dolphins 105 0 246 342 439.2

Short-finned pilot whales 106 1 240 330 425

Sperm whales 15 1 166 349 386.5

Dwarf sperm whales 7060 1053 209 343 405

SPL=sound pressure level; SEL=sound exposure level; rms=root-mean-square.

Table 15. Number of modeled cetaceans above exposure criteria for Survey site B for entire duration of the 

simulations. Simulations for zero-to-Peak SPL and SEL injury metrics were 5 day duration with animat density of 

2.0 animats/km2

. Simulations for rms SPL metrics were 30 day duration with animat density of 0.1 animats/km2. 

Marine mammal species

Injury Behavior

zero-topeak SPL SEL 180 dB 

rms SPL

160 dB 

rms SPL

Step fxn. 

rms SPL

Bryde’s whales 51 485 313 357 529.8

Cuvier’s beaked whales 38 0 300 491 1829.2

Common bottlenose dolphins 99 0 254 285 411

Short-finned pilot whales 102 0 263 315 426.6

Sperm whales 35 0 381 701 789.9

Dwarf sperm whales 7246 893 242 337 417.7

SPL=sound pressure level; SEL=sound exposure level; rms=root-mean-square

6.3.3. Real-world Individual Exposure Estimates

Simulations were run with animat densities (animats/km2) greater than are typically found in the real 

world in order to generate reliable exposure probability density functions for each species. The numbers 

of exposures, therefore, must be adjusted for the species real-world density. Minimum, maximum, and 

mean regional real-world densities estimates were obtained from the U.S. Navy OPAREA Density 

Estimate (NODE) model for the Gulf of Mexico (DoN 2007, as shown in Section 6.2.5 and Table 11). 

The real-world number of cetacean individuals expected to exceed the injury exposure criteria is shown 

for Survey sites A and B in Tables 16 and 17, respectively. Likewise, the real-world number of cetacean 

individuals expected to exceed the behavioral disruption exposure criteria is shown for Survey sites A and 

B in Tables 18 and21, respectively.
D-54 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 16. Real-world number of cetaceans above injury exposure criteria for summer for Survey site A.

Marine mammal species

peak SPL SEL 180 dB rms SPL

Min Max Mean Min Max Mean Min Max Mean

Bryde’s whales < 0.01 < 0.01 < 0.01 < 0.01 0.03 0.02 < 0.01 0.37 0.28

Cuvier’s beaked whales < 0.01 0.03 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 59.56 5.43

Common bottlenose dolphins < 0.01 5.62 0.73 < 0.01 0.05 0.01 < 0.01 714.63 53.65

Short-finned pilot whales < 0.01 0.14 0.11 < 0.01 < 0.01 < 0.01 < 0.01 15.06 11.63

Sperm whales < 0.01 0.42 0.14 < 0.01 < 0.01 < 0.01 < 0.01 45.68 4.73

Dwarf sperm whales < 0.01 16.30 2.38 < 0.01 2.42 0.35 < 0.01 11.59 1.29

SPL=sound pressure level; SEL=sound exposure level; rms=root-mean-square; min=minimum; max=maximum

Table 17. Real-world number of cetaceans above injury exposure criteria for summer for Survey site B.

Marine mammal species

peak SPL SEL 180 dB rms SPL

Min Max Mean Min Max Mean Min Max Mean

Bryde’s whales < 0.01 < 0.01 < 0.01 < 0.01 0.03 0.02 < 0.01 0.33 0.30

Cuvier’s beaked whales < 0.01 0.07 0.01 < 0.01 < 0.01 < 0.01 < 0.01 52.26 5.49

Common bottlenose dolphins < 0.01 4.21 0.08 < 0.01 < 0.01 < 0.01 < 0.01 250.42 8.20

Short-finned pilot whales < 0.01 0.12 0.11 < 0.01 < 0.01 < 0.01 < 0.01 16.51 15.21

Sperm whales < 0.01 0.27 0.11 < 0.01 < 0.01 < 0.01 < 0.01 104.85 13.57

Dwarf sperm whales < 0.01 56.45 5.76 < 0.01 6.95 0.71 < 0.01 33.15 3.33

SPL=sound pressure level; SEL=sound exposure level; rms=root-mean-square; min=minimum; max=maximum

Table 18. Real-world number of cetaceans above behavioral exposure criteria for summer for Survey site A.

Marine mammal species

Step fxn. max. rms SPL 160 dB rms SPL

Min Min Min Min Max Mean

Bryde’s whales < 0.01 0.76 0.59 < 0.01 0.60 0.46

Cuvier’s beaked whales 0.10 140.57 23.06 < 0.01 124.52 11.34

Common bottlenose dolphins < 0.01 522.16 67.69 < 0.01 993.51 74.59

Short-finned pilot whales < 0.01 30.18 23.29 < 0.01 20.71 15.99

Sperm whales 0.16 35.96 12.18 < 0.01 96.04 9.95

Dwarf sperm whales < 0.01 20.75 3.03 < 0.01 19.03 2.12

SPL=sound pressure level; rms=root-mean-square; min=minimum; max=maximum
Gulf of Mexico G&G Activities Programmatic EIS D-55

Table 19. Real-world number of cetaceans above behavioral exposure criteria for summer for Survey site B.

Marine mammal species

Step fxn. max. rms SPL 160 dB rms SPL

Min Min Min Min Max Mean

Bryde’s whales < 0.01 0.75 0.69 < 0.01 0.37 0.35

Cuvier’s beaked whales < 0.01 99.11 19.46 < 0.01 85.53 8.98

Common bottlenose dolphins < 0.01 383.18 6.93 < 0.01 280.98 9.20

Short-finned pilot whales < 0.01 29.41 27.10 < 0.01 19.77 18.22

Sperm whales 3.31 48.99 20.98 < 0.01 192.92 24.97

Dwarf sperm whales 0.01 71.12 7.25 0.01 46.17 4.64

SPL=sound pressure level; rms=root-mean-square; min=minimum; max=maximum

6.4. Test Case Exposure Summary

The estimated number of animals exposed to levels exceeding the acoustic exposure thresholds was 

determined for the two WAZ survey sites. For injury, it was found that relative to the other species, a 

large number of dwarf sperm whales may be exposed to levels exceeding both the SEL and zero-to-peak 

SPL thresholds. It was also found that a relatively high number of Bryde’s whales may be exposed to 

levels exceeding the SEL injury threshold. Dwarf sperm whales are a high-frequency species with greater 

susceptibility to injury than the other species. For this reason, injury thresholds were lower for dwarf 

sperm whales and as a result the number of animats exposed to levels exceeding threshold was higher. 

Bryde’s whales are low frequency animals and most of the acoustic energy emanating from an airgun is 

low frequency. Because less restrictive filtering (Type I M weighting) was used to calculate the sound 

field for the low-frequency species, the ensonified area above threshold was much greater than for midfrequency species and therefore the number of animats exposed to levels exceeding threshold is higher. 

For Bryde’s whales, the estimated real-world density is low so the predicted real-world number of 

animals exposed to levels exceeding injury criteria is less than one animal. The estimated real-world 

density of dwarf sperm whales is higher and, therefore, the predicted number of real-world animals 

exposed to levels exceeding injury threshold was up to 56.5 animals (Survey site B and maximum density 

estimate).

The volume over which behavioral disturbance may occur is greater than the volume over which injury 

may occur. Animats for all species were found to exceed thresholds for potential behavioral disturbance. 

Cuvier’s beaked whales had the greatest number of exceedances because, as a behaviorally sensitive 

species, the step function used to assess their potential for behavioral disturbance starts at lower sound 

levels (120 dB rms SPL versus 140 dB rms SPL for the remaining species). It was also found that Bryde’s 

whales and sperm whales had higher exceedance than the common bottlenose dolphins, short-finned pilot 

whales, and dwarf sperm whales. Because the majority of acoustic energy from the airguns is in the low 

frequency band (< 1500 Hz) and the low-frequency weighting function permits more low-frequency 

energy to propagate, the ensonified volume above threshold was larger for low frequency species and 

results in more animats exposed to sounds above the thresholds. Sperm whales are deep-diving animals 

and in the downward-refracting acoustic environment are more consistently exposed to sound levels 

above threshold when diving. This is apparent at Survey site B where a behavioral response was predicted 

for approximately twice as many sperm whale animats (908) as common bottlenose dolphin, short-finned 

pilot whale, and dwarf sperm whale animats (all ~ 450). At Survey site A, the number behavioral 

responses predicted for sperm whales was about the same as the predictions for common bottlenose 

dolphin, short-finned pilot whale, and dwarf sperm whale animats (all ~ 450). The reason for the 

difference in the number of behavioral responses predicted for sperm whales at the two sites is that 
D-56 Acoustic Propagation and Marine Mammal Exposure Modeling

Survey site A is shallower than Survey site B. Sperm whales generally do not enter water shallower than 

1000 m, so during the simulation the animats changed swimming direction to avoid depths < 1000 m. In 

addition, because much of the area at Survey site A is < 1000 m, a smaller number of animats were used 

during the simulation (animats are not seeded in depth-restricted areas) so that the animat density 

remained consistent for all simulations. 

6.5. Test Scenarios

Primarily using the results of the Test Case, several scenarios were investigated to determine their 

potential effects on exposure estimates and to inform the main modeling effort. 

Scenarios investigated were: 

• Long-duration surveys (Section 6.5.1), 

• Sources and effects of uncertainty (Section 6.5.2), 

• Mitigation (Section 6.5.3), 

• Aversion (Section 6.5.4), 

• Stand-off distance (Section 6.5.5.1), and

• Simultaneous firing of sources (Section 6.5.5.2). 

6.5.1. Test Scenario 1: Scaling Modeled Acoustic Exposure Estimates

Some seismic surveys operate (nearly) continuously for several months. Evaluating the potential impacts 

due to underwater sound exposures from these extended operations is challenging because assumptions 

about parameters that are valid for short-duration simulations may become less valid, or more varied, as 

the time period increases. For example, the average sound velocity profile changes as the surface layer 

temperature changes. Also large-scale animal movement, such as migrations or prey movement, may 

change the density estimate of animals in the simulation area. Treating such parameters as constant, as is 

typically done in shorter duration simulations, could lead to errors. Systematic bias in modeling processes 

may also lead to increasing error as the simulation time is increased. Simulated animals (animats) may 

settle into unrealistic behaviors such as following an arbitrary boundary, or, if animats are allowed to 

leave the simulation area without a replacement method, a diffusion process will systematically decrease 

the density. 

This Test Scenario investigates the potential impacts of large-scale animal movement and possible 

systematic bias in the modeling process. Methods for scaling results from shorter-duration simulations to 

longer duration operations are suggested.

6.5.1.1. Large-scale Animal Movement

Current agent-based animal movement models, such as the Marine Mammal Movement and Behavior 

(3MB) model (Houser 2006), estimate movement from the current disposition of a simulated animal. 

Limited, or no, memory of prior states is considered when generating movement changes, such as change 

of direction or swim speed. These models generate realistic behavior (using swimming and diving 

parameters) over short durations (days to weeks). They become increasingly less valid as durations are

extended because they may not include the effects of long-term behaviors. The models do not account for 

animal movements on large temporal or spatial scales, and this also may lead to errors. Large-scale 
Gulf of Mexico G&G Activities Programmatic EIS D-57

marine mammal movement in the Gulf of Mexico and its potential as a source of error in the acoustic 

exposure estimates is discussed in the subsections below, and further in section 6.5.1.3.1. 

6.5.1.1.1. Scaling Methods

The available literature on cetacean distribution and behavior for the six Gulf of Mexico species studied 

in the Test Case were examined for information on large-scale movement and seasonality. The majority 

of the Test Case species prefer deeper water (> 200 m), which makes it difficult to obtain detailed 

information on their distribution and movements. If no quantitative information could be found, 

knowledge of behavioral and feeding ecology for the species was used to infer possible movement 

patterns and large-scale movement behavior.

6.5.1.1.2. Assumptions

Potential movement patterns were based on available information regarding the general behavioral and 

feeding ecologies of the species in question and observed interactions of the species/populations with the 

environment. The patterns do not account for evolved programs, such as adaptive predator responses 

(spatial and temporal movement patterns due to behavioral programming to reduce predation risks) or 

intra- and interspecies competition for resources, as the available information is insufficient to discuss 

their relevance.

6.5.1.1.3. Prey Distribution as an Environmental Attractor

The distribution of plankton in the deeper waters of the Gulf of Mexico, especially the northern and 

eastern parts of the Gulf, is controlled by the loop current (Mullin and Fulling 2004). The temporal 

movement of all organisms, including marine mammals and their prey, may be effected by upwelling of 

nutrient rich cold water eddies (Davis et al. 2001); however, habitat use appears to be more directly 

correlated with static features such as water depth, bottom gradient, and longitude (Mullin and Fulling 

2004). Temporal fluctuation near the surface can cause changes in diurnal movement patterns in squid, 

which prefer colder water, but does not substantially affect cetaceans feeding on squid in deeper waters. 

As a result, the occurrences of the four Test Case odontocetes that rely on squid as a main food source are 

only affected by water temperature when deeper layers are affected, which is rarely the case. A more 

critical consequence of feeding on squid that may cause the whales to leave an area may be that squid 

may learn to avoid the whales by moving to different areas (Long et al. 1989). 

6.5.1.1.4. Distribution and Movement Behavior of Modeled Species

Common Bottlenose Dolphins

Common bottlenose dolphins travel and forage in close association with short-finned pilot whales and 

other species that feed on squid (NOAA Fisheries 2012a), but since common bottlenose dolphins do not 

regularly perform deep foraging dives, large-scale movements are likely driven by fish movement in the 

upper ocean layers. The one offshore common bottlenose dolphin population that feeds primarily on 

schooling fish, but also on squid, is less driven by the vertical diurnal movements of squid (Barros and 

Odell 1990, Barros and Wells 1998). Other oceanic delphinids, such as some spotted dolphins travel 55–

90 km/day (Mullin and Fulling 2004) possibly following fish schools, such as tuna. Common bottlenose 

dolphin density in a given area is likely to fluctuate because they travel at high speed and in groups of 

more than 100 individuals (NOAA Fisheries 2015a). 
D-58 Acoustic Propagation and Marine Mammal Exposure Modeling

Sperm Whales 

Most sperm whales are found in very deep waters (> 3,000 m), but can be encountered in waters as 

shallow as 300 m. Male and female sperm whales are not usually encountered together, and females are 

rarely found in waters less than 1000 m deep (Taylor et al. 2008a). 

In the northern Gulf of Mexico, sperm whales occur year round, but at higher densities during the 

summer. There are no discernable seasonal migrations, but Gulf-wide movements occur primarily along 

the northern Gulf slope. Tracks show that whales exhibit a range of movement patterns within the Gulf, 

including movement into the southern Gulf in a few cases (Waring et al. 2013, NOAA Fisheries 2015b). 

Kingsley and Stirling (1991) reported movements of groups of female sperm whales from different vocal 

clans ranging from less than 10 km to over 100 km in 24 h. The movements appeared to be driven by 

differences in dominance rankings between clans; more dominant groups often displace lower ranking 

clans. This likely causes rapid displacement movement patterns in areas of high prey concentrations. 

These rapid movements of groups of females due to displacement may show short-term changes in 

density, but are not likely considerable in magnitude. 

Dwarf Sperm Whales 

Dwarf sperm whales prefer warm tropical, subtropical, and temperate waters worldwide. They are most 

common along the waters of the continental shelf edge and the slope; dwarf sperm whales are thought to 

be more "coastal" than pygmy sperm whales (NOAA Fisheries 2012b). 

There is very little information on dwarf sperm whales feeding habits, other than a preference for squid. 

Information on movement behaviors is practically absent. The density of dwarf sperm whales in the Gulf 

is considered very low, and members of the species either travel alone or groups of 6–10 animals (NOAA 

Fisheries 2012b). Würsig et al. (1998) notes that dwarf sperm whales are difficult to survey because they 

avoid ships and airplanes. This could mean that their density is generally underestimated.

Short-finned Pilot Whales

These whales occur in tropical to cool temperate waters. Sightings in the northern Gulf of Mexico (i.e., 

U.S. Gulf of Mexico) occur primarily on the continental slope west of 89 ̊W. There appears to be a year 

round aggregation of short-finned pilot whales in nutrient rich waters off the Mississippi River outflow. 

In other areas, pilot whales travel constantly (Mullin and Fulling 2004). 

Short-finned pilot whales often occur in groups of 25–50 animals and often co-occur with common 

bottlenose dolphins and other delphinids. This species feeds on vertically migrating prey, with deep dives 

at dusk and dawn following vertically migrating prey and near-surface foraging at night (Baird et al. 

2003). When they are swimming and probably looking for food, pilot whales form ranks that can be over 

a kilometer long (Taylor et al. 2011). 

Based on food preference and group size information, it appears that short-finned pilot whales may need 

to travel over large distances to sustain groups of the reported sizes. This will lead to fluctuating densities 

in any given area as groups of 25–50 animals are possibly widely dispersed in order to avoid competition 

for patchy food sources. Squid abundance in any given area will be affected by groups of that size and the 

fact that pilot whales often occur together with odontocetes feeding on the same prey would underline the 

need for large-scale movement in this species.

Cuvier’s Beaked Whales 

Beaked whales were seen in all seasons during GulfCet aerial surveys of the northern Gulf of Mexico 

(Waring et al. 2013). Like many beaked whales, Cuvier’s beaked whales eat mostly deep water squid and 

octopus near the bottom, but will eat fish and crustaceans in the water column. They prefer deep waters 

(depths usually greater than 1,000 m) of the continental slope, as well as steep underwater geologic 
Gulf of Mexico G&G Activities Programmatic EIS D-59

features like banks, seamounts, and submarine canyons. Recent surveys suggest that beaked whales, like 

this species, may favor oceanographic features such as currents, current boundaries, and core ring features 

(Taylor et al. 2008b). 

Cuvier’s beaked whales occur individually or in small groups of 2–12 animals (NOAA Fisheries 2012c). 

Like most beaked whales, information on behavior is sparse, and movements are not well understood. 

Given their small group sizes, but highly specialized foraging on squid, these whales probably remain in 

the same area longer than pilot whales. Information on aggregations is not available, which means density 

fluctuation in a given area is unknown and cannot be accurately assessed. The reported foraging locations 

over steep topographical structures may indicate avoidance of competition with other odontocetes 

foraging on the same prey. This may allow Cuvier’s beaked whales to remain longer in a specific area. 

Bryde’s Whales

Bryde’s whales are often characterized as displaying erratic and strange behavior relative to other baleen 

whales because they surface for irregularly spaced time intervals and can unexpectedly change directions 

(NOAA Fisheries 2014). These large baleen whales are usually sighted individually or in pairs, but there 

are reports of loose aggregations of up to twenty animals associated with feeding areas. These whales 

feed opportunistically on plankton, crustaceans, and schooling fish. They regularly dive for about 5–

15 min (maximum of 20 min) after 4–7 blows at the surface. Bryde’s whales are capable of reaching 

depths up to 300 m during dives (NOAA Fisheries 2014). 

Given the information about feeding behavior and grouping, it appears unlikely that animals move rapidly 

between feeding areas. There is no information on large-scale movements, but aggregations could be the 

result of animals moving synchronously toward a certain area of high primary productivity. Bryde’s 

whale distribution and movements are affected by plankton occurrence, which can be patchy due to the 

presence of large, warm-water eddies in the Gulf of Mexico.

6.5.1.2. Potential Biases in the Modeling Procedure

Underlying, and perhaps unknown, systematic biases in model procedures may lead to errors that could 

increase with modeling run duration. 

6.5.1.2.1. Methods

Exposure estimates from 30 day (0.1 animats/km2

) and 5 day (2.0 animats/km2) wide azimuth survey 

simulations from the Test Case (Section 6.3.2) were determined in subsets using a ‘sliding window’ to 

find the number of exposures as a function of time. The length of the sliding window was 24 h, advanced 

by 4 h, resulting in 174 samples from the 30 day simulation and 25 samples from the 5 day simulation. A 

sliding window of 7 days advancing by 1 day for the 30 day simulation was also be evaluated. Exposures 

were calculated using the behavioral threshold criteria indicated in the Test Case (Section 5.4.3). Bias in 

the model was expected to manifest itself as a trend in the exposure levels as a function of time. 

The survey vessel paths in the simulations begin in the south east corner of the survey area, proceed on a 

westward longitudinal production line, step north at the end of the survey area, and then start on an 

eastward longitudinal production line (Figures 19 and 20). Simulations with ‘reversed’ track lines at 

Survey site A (starting in the northwest corner of the survey area, initially proceeding eastward on a 

longitudinal production line, and then stepping south) were also analyzed for short-finned pilot whales 

and sperm whales. To eliminate trends and variance due to changing sound fields (as the vessels move) 

and depth constraints, simulations were run with a stationary source in deep water (2000 m) and a flat 

bottom. 
D-60 Acoustic Propagation and Marine Mammal Exposure Modeling

During all simulations in this project, any animat that left the simulation area as it crossed the simulation 

boundary was replaced by a new animat traveling in the same direction and entering at the opposite 

boundary. For example, an animat heading north and crossing the northern boundary of the simulation 

was replaced by a new animat heading north and entering at the southern boundary. By replacing animats 

in this manner, the animat modeling density remained constant. 

Also common to all analysis in this project was that animats were only allowed to be ‘taken’ once during 

an evaluation period. That is, an animat whose received level exceeds the peak SPL threshold more than 

once during an evaluation period (i.e., 24 h, 7 day, or 30 day) was only counted once. Energy 

accumulation for SEL occurred throughout the evaluation period and was reset at the beginning of each 

period. Similarly, the maximum received rms SPL was determined for the entirety of the evaluation 

period and reset at the beginning of each period. The consequences of using a short time-period, such as 

24 h, was evaluated. 

6.5.1.2.2. Results

The number of animats exposed to levels exceeding the behavioral step function criteria in 30 day 

simulations evaluated using a 24 h sliding window are shown in Figure 21 for the low-frequency Bryde’s 

whales at Survey sites A and B. In Figure 21, least-squares fitted trend lines show a positive trend at 

Survey site A indicating increasing exposures as function of simulation time, and a negative trend at 

Survey site B indicating decreasing exposures as a function of simulation time, but residual analysis did 

not find either trend to be significant. For the other species, the trend lines at Survey site A, though not 

necessarily significant, were negative, indicating decreasing exposures as a function of simulation time: 

common bottlenose dolphins (Figure 22a), Cuvier’s beaked whales (Figure 23a), short-finned pilot 

whales (Figure 24a), sperm whales (Figure 25a), and dwarf sperm whales (Figure 26a). The trend lines at

Survey site B for these species (Figure 22b–26b) were less pronounced, positive for common bottlenose 

dolphins and sperm whales, and negative for Cuvier’s beaked whales, short-finned pilot whales, and 

dwarf sperm whales. 

The exposure estimates as a function of simulation time and trend lines for ‘reversed’ track lines are 

shown in Figure 27. For short-finned pilot whales and sperm whales, the trend lines were positive. 

Figure 28 shows that the variability in the exposure estimates decreased, and there was no significant 

trend as a function of simulation time when the source was stationary and there were no depth constraints 

on the animats. 

(a) (b) 

Figure 21. Bryde’s whales: Behavioral exposure estimates for (a) Survey sites A and (b) B. Exposure 

estimates are for 24 h sliding windows (samples), which advance in 4 h increments during 30 
Gulf of Mexico G&G Activities Programmatic EIS D-61

day simulations. Circle markers indicate exposure estimates during each 24 h sample period, 

dashed red line is a least-squares fit. 

(a) (b) 

Figure 22. Common bottlenose dolphins: Behavioral exposure estimates for (a) Survey sites A and (b) B. 

Exposure estimates are for 24 h sliding windows (samples), which advance in 4 h increments 

during 30 day simulations. Circle markers indicate exposure estimates during each 24 h 

sample period, dashed red line is a least-squares fit.

(a) (b) 

Figure 23. Cuvier’s beaked whales: Behavioral exposure estimates for (a) Survey sites A and (b) B. 

Exposure estimates are for 24 h sliding windows (samples), which advance in 4 h increments 

during 30 day simulations. Circle markers indicate exposure estimates during each 24 h 

sample period, dashed red line is a least-squares fit.
D-62 Acoustic Propagation and Marine Mammal Exposure Modeling

(a) (b) 

Figure 24. Short-finned pilot whales: Behavioral exposure estimates for (a) Survey sites A and (b) B. 

Exposure estimates are for 24 h sliding windows (samples), which advance in 4 h increments 

during 30 day simulations. Circle markers indicate exposure estimates during each 24 h 

sample period, dashed red line is a least-squares fit. 

(a) (b) 

Figure 25. Sperm whales: Behavioral exposure estimates for (a) Survey sites A and (b) B. Exposure 

estimates are for 24 h sliding windows (samples), which advance in 4 h increments during 

30 day simulations. Circle markers indicate exposure estimates during each 24 h sample 

period, dashed red line is a least-squares fit. 
Gulf of Mexico G&G Activities Programmatic EIS D-63

(a) (b) 

Figure 26. Dwarf sperm whales: Behavioral exposure estimates for (a) Survey sites A and (b) B. Exposure 

estimates are for 24 h sliding windows (samples), which advance in 4 h increments during 

30 day simulations. Circle markers indicate exposure estimates during each 24 h sample 

period, dashed red line is a least-squares fit.

(a) (b) 

Figure 27. Behavioral exposure estimates for (a) short-finned pilot whales and (b) sperm whales, both 

with reversed vessel tracks at Survey site A. Exposure estimates are for 24 h sliding windows 

(samples), which advance in 4 h increments during 30-day simulations. Circle markers 

indicate exposure estimates during each 24 h sample period, dashed red line is a least-squares 

fit. 
D-64 Acoustic Propagation and Marine Mammal Exposure Modeling

 

(a) (b) 

Figure 28. Behavioral exposure estimates for (a) short-finned pilot whales and (b) sperm whales, with 

stationary source in deep water near Survey site B. Exposure estimates are for 24 h sliding 

windows (samples), which advance in 4 h increments during 30 day simulations. Circle 

markers indicate exposure estimates during each 24 h sample period, dashed red line is a 

least-squares fit.

The Test Case preliminary results found the number of animats exposed to levels exceeding threshold 

criteria for the entire duration of the simulations—5 days for the zero-to-peak SPL and SEL and 30 days 

for the criteria based on rms SPL (Table 14 and Table 15). It is often impractical or unwarranted to 

integrate exposures for an entire survey and an integration window is defined. A 24 h time-period for 

determining potential impacts is commonly used. Table 20 and Table 21 show the average number of 

animats receiving levels exceeding exposure criteria in the 24 h sliding windows at Survey sites A and B, 

respectively. To estimate the number of animats receiving levels exceeding threshold for a longer 

duration survey, the 24 h average was scaled by the survey duration in days. Table 22 and Table 23 show 

the 24 h averages scaled to the simulation length (5 days for zero-to-peak SPL and SEL, and 30 days for 

the criteria based on rms SPL) and the percentage of the full-duration estimates that the scaled values 

represent (shown in parenthesis). It can be seen in Tables 22 and 23 that when scaling the 24 h averages 

for the rms SPL-based criteria, the percentages were uniformly positive, indicating that scaling resulted in 

a greater number of animats predicted to received levels exceed these criteria. The increased number of 

animats estimated to exceed threshold could be quite large, several times the estimate for the full duration 

(100% is twice the full duration estimate). For the zero-to-peak and SEL metrics the difference between 

the scaled estimates and the full-duration estimates was smaller and the scaled values may be less than the 

full duration values (indicated by a negative percentage). Because SEL accumulates throughout the 

evaluation period, it is possible that some animats’ received level SELs would not exceed threshold in 24 

h, but would when integrated over the full duration of the simulation. The zero-to-peak SPL criteria does 

not accumulate and animats were only counted once per evaluation period, so a reduced number of 

estimated exceedances for the scaled values compared to the full-duration values was not expected. To 

investigate, the 24 h estimates were scaled (by 4) and compared to a 4 day evaluation period starting 12 h 

into the 5 day simulation. Tables 26 and 27 shows that the percentage difference between the scaled 

estimates and the 4 day estimates were positive, except for SEL for short-finned pilot whales and zero-topeak SPL for sperm whales, which are very rare events, and the negative percentage results from a 

rounding error (e.g., there was one short-finned pilot whale above the zero-to-peak SPL threshold for the 

entire simulation, but the 24 h average was ~ 0.23 and rounded to 0.2). 

Knowing the amount of time that animals are exposed to levels exceeding the threshold criteria can 

provide additional information about the potential impacts. Tables 26 and 27 show the mean time that 
Gulf of Mexico G&G Activities Programmatic EIS D-65

levels exceeded the NMFS criteria of 180 dB rms SPL re 1 μPa (Level A Harassment) and 160 dB rms 

SPL re 1 μPa (Level B Harassment) for the entire duration of the 30 day simulation and the averaged 

mean time in the 24 h sliding windows. The times only consider animats exposed to levels that exceed the 

criteria and the distributions of exceedance times are not normally distributed. The exceedance-time 

distributions are better fit by a Poisson model (not shown), but it is improper to fit these distributions 

because the animats whose received levels are below threshold are not considered (i.e., the number of 

animats with zero time above threshold exposure is indefinable because it changes with the arbitrary 

choice of simulation boundaries). For this reason, we report the mean value (equivalent to lambda for a 

Poison distribution) and the maxim time that an animat was exposed leveling exceeding threshold. Other 

criteria, such as SEL and zero-to-peak SPL injury criteria were not considered. SEL was not considered 

because it only positively accumulates; once the SEL threshold is reached it does not decrease even 

though the animal may have moved away from the source. Zero-to-peak SPL is meant for evaluating onetime exposures to very loud sounds that may do mechanical damage to the ear, once damage has occurred 

it is not expected to regain function.

The amounts of time that animats were exposed to levels exceeding the 160 dB rms SPL re 1 μPa 

threshold over the 30 day duration were approximately twice as long as the average times in a 24 h 

window. Whereas, the amounts of time that exposure levels exceeded the 180 dB rms SPL re 1 μPa 

threshold over the 30 day duration were closer to the average times in a 24 h window. The exceedance 

times of the 180 dB rms SPL re 1 μPa threshold were similar because threshold exceedance was a 

relatively rare event and was not usually repeated (an individual animat was not often exposed to levels 

exceeding this threshold in multiple separated events). There were more opportunities for animats to be 

exposed to levels exceeding the 160 dB rms SPL re 1 μPa threshold, so there were more instances when 

this threshold was reached and it was more common for the threshold to be exceeded on multiple separate 

occasions. Exceedance on multiple occasions accounts for the increased exceedance times for the 30 day 

duration relative to the 24 h average. The amount of time when either threshold was exceeded was short 

relative to the evaluation period (24 h or 30 days). Two factors contributed to the total time thresholds 

were exceeded—the amount of time per occasion (i.e., how long an animat was near the source) and the 

number of occasions that occur (i.e., how many times an animat was near a source). The number of 

occasions was, essentially, the same item determined when finding the number of animats with exposures 

exceeding threshold criteria (the typical use of the threshold criteria). As was investigated above, the 

number of occasions scales with the duration of the evaluation period, but the time per occasion does not. 

The time per occasion is specific to how an individual animat interacted with a source. It is, therefore, 

inappropriate to scale the 24 h exceedance times to estimate the exceedance times for longer durations.

Table 20. Average number of modeled cetaceans above exposure criteria at Survey site A for 24 h sliding windows. 

Simulations for zero-to-Peak SPL and SEL injury were 5 day duration with animat density of 2.0 animats/km2

. 

Simulations for rms SPL metrics were 30 day duration with animat density of 0.1 animats/km2

. 

Marine mammal species

Injury Behavior

zero-topeak SPL SEL 180 dB 

rms SPL

160 dB 

rms SPL

Step fxn. 

rms SPL

Bryde’s whales 8.1 105.5 15.6 113 115.4

Cuvier’s beaked whales 8.6 0 10.5 38.1 715.3

Common bottlenose dolphins 20.3 0 10.9 32.2 57.3

Short-finned pilot whales 21.1 0.2 10.2 29.5 55.1

Sperm whales 2.9 0.2 6 19.3 32.4

Dwarf sperm whales 1871.7 207.7 8.7 26 49.8

SPL=sound pressure level; SEL=sound exposure level; rms=root-mean-square
D-66 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 21. Average number of modeled cetaceans above exposure criteria at Survey site B for 24 h sliding windows.

Simulations for zero-to-Peak SPL and SEL injury were 5 day duration with animat density of 2.0 animats/km2

. 

Simulations for rms SPL metrics were 30 day duration with animat density of 0.1 animats/km2

. 

Marine mammal species

Injury Behavior

zero-topeak SPL SEL 180 dB 

rms SPL

160 dB 

rms SPL

Step fxn. 

rms SPL

Bryde’s whales 10.6 93.7 14.3 41.6 90.5

Cuvier’s beaked whales 8.6 0 11.3 30.9 538

Common bottlenose dolphins 18.9 0 11 24.9 42.1

Short-finned pilot whales 19.9 0 10.7 24.5 41

Sperm whales 6.5 0 14.3 40.53 58.1

Dwarf sperm whales 1892.2 193.2 9.8 25.4 35.5

SPL=sound pressure level; SEL=sound exposure level; rms=root-mean-square

Table 22. Number of modeled cetaceans above exposure criteria at Survey site A for average 24 h sliding windows 

estimate scaled to full duration (5 or 30 days). Numbers in parenthesis represent the percentage change relative to 

the full duration estimate. Positive numbers indicate the scaled value is greater than full duration estimate. +100% is 

a doubling of the full duration estimate.

Marine mammal species

Injury Behavior

zero-to-peak 

SPL SEL 180 dB rms SPL

160 dB rms 

SPL

Step fxn. rms 

SPL

Bryde’s whales 40.5 (−14) 527.5 (−1) 468.0 (35) 3390.0 (494) 3462.0 (444)

Cuvier’s beaked whales 43 (−4) 0 (0) 315.0 (14) 1143.0 (98) 21459.0 (1006)

Common bottlenose dolphins 101.5 (−3) 0 (0) 327.0 (33) 966.0 (183) 1719.0 (291)

Short-finned pilot whales 105.5 (0) 1 (0) 306.0 (28) 885.0 (168) 1653.0 (289)

Sperm whales 14.5 (−3) 1 (0) 180.0 (8) 579.0 (66) 972.0 (152)

Dwarf sperm whales 9358.5 (33) 1038.5 (−1) 261.0 (25) 780.0 (127) 1494.0 (269)

SPL=sound pressure level; SEL=sound exposure level; rms=root-mean-square

Table 23. Number of modeled cetacean animats above exposure criteria at Survey site B for average 24 h sliding 

windows estimate scaled to full duration (5 or 30 days). Numbers in parenthesis represent the percentage change 

relative to the full duration estimate. Positive numbers indicate the scaled value is greater than full duration estimate. 

+100% is a doubling of the full duration estimate.

Marine mammal species

Injury Behavior

zero-to-peak 

SPL SEL 180 dB rms SPL

160 dB rms 

SPL

Step fxn. rms 

SPL

Bryde’s whales 53 (4) 468.5 (−3) 429.0 (37) 1248.0 (250) 2715.0 (412)

Cuvier’s beaked whales 43 (13) 0 (0) 339.0 (13) 927.0 (89) 16140.0 (782)

Common bottlenose dolphins 94.5 (−5) 0 (0) 330.0 (30) 747.0 (162) 1263.0 (207)

Short-finned pilot whales 99.5 (−2) 0 (0) 321.0 (22) 735.0 (133) 1230.0 (188)

Sperm whales 32.5 (−7) 0 (0) 429.0 (13) 1215.9 (74) 1743.0 (121)

Dwarf sperm whales 9461 (31) 966 (8) 294.0 (22) 762.0 (126) 1065.0 (155)

SPL=sound pressure level; SEL=sound exposure level; rms=root-mean-square
Gulf of Mexico G&G Activities Programmatic EIS D-67

Table 24. Percentage difference in number of modeled cetaceans above exposure criteria at Survey site A for 24 h 

sliding windows scaled to 4 day evaluation window.Positive numbers indicate the scaled value is greater than 4 day 

estimate. +100% is a doubling of the 4 day estimate. 

Marine mammal species

Injury

zero-topeak SPL SEL

Bryde’s whales 8 12

Cuvier’s beaked whales 23 0

Common bottlenose dolphins 25 0

Short-finned pilot whales 13 −20

Sperm whales −17 0

Dwarf sperm whales 43 10

SPL=sound pressure level; SEL=sound exposure level

Table 25. Percentage difference in number of modeled cetaceans above exposure criteria at Survey site B for 24 h 

sliding windows scaled to 4 day evaluation window. Positive numbers indicate the scaled value is greater than 4 day 

estimate. +100% is a doubling of the 4 day estimate.

Marine mammal species

Injury

zero-topeak SPL SEL

Bryde’s whales 9 12

Cuvier’s beaked whales 50 0

Common bottlenose dolphins 16 0

Short-finned pilot whales 15 0

Sperm whales 30 0

Dwarf sperm whales 39 21

SPL=sound pressure level; SEL=sound exposure level

Table 26. Amount of time that animats exceed NMFS threshold criteria at Survey site A for 30 days and 24 h. The 

average amount of time, in minutes, that animats exposed to levels exceeding the criteria remain above the criteria is 

shown. The maximum amount of time an animat exceeded the threshold is shown in parentheses. 30 days show the 

results for the entire duration of the simulation, 24 h show the average values from the 24-h sliding windows. 

Marine mammal species

30 day 24 h

180 dB rms 

SPL

160 dB rms 

SPL

180 dB rms 

SPL

160 dB rms 

SPL

Bryde’s whales 2.2 (10) 75.6 (554) 1.6 (3.4) 18 (83)

Cuvier’s beaked whales 1.5 (4) 8.2 (48) 1.3 (2.4) 4.8 (16)

Common bottlenose dolphins 1.9 (8) 12.6 (115) 1.4 (2.7) 5.7 (17.8)

Short-finned pilot whales 1.8 (8) 12 (73) 1.4 (2.4) 5.7 (18.3)

Sperm whales 1.5 (6) 5.2 (35) 1.3 (2.1) 3.7 (10.5)

Dwarf sperm whales 1.5 (6) 8.6 (63) 1.3 (2.2) 4.6 (14.3)

SPL=sound pressure level; rms=root-mean-square
D-68 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 27. Amount of time that animats exceed NMFS threshold criteria at Survey site B for 30 days and 24 h.The 

average amount of time, in minutes, that animats exposed to levels exceeding the criteria remain above the criteria is 

shown. The maximum amount of time an animat exceeded the threshold is shown in parentheses. 30 days show the 

results for the entire duration of the simulation, 24 h show the average values from the 24-h sliding windows.

Marine mammal species

30 day 24 h

180 dB rms 

SPL

160 dB rms 

SPL

180 dB rms 

SPL

160 dB rms 

SPL

Bryde’s whales 2.2 (10) 20.5 (131) 1.6 (3.5) 8.1 (38)

Cuvier’s beaked whales 1.5 (5) 6.2 (30) 1.3 (2.4) 3.9 (12.4)

Common bottlenose dolphins 1.8 (6) 8.8 (45) 1.4 (2.7) 4.4 (13.3)

Short-finned pilot whales 1.7 (7) 8.2 (58) 1.4 (2.7) 4.4 (13.5)

Sperm whales 1.4 (5) 5.3 (33) 1.3 (2.6) 3.5 (11.5)

Dwarf sperm whales 1.5 (6) 7.3 (52) 1.3 (2.4) 4.0 (11.7)

SPL=sound pressure level; rms=root-mean-square

6.5.1.3. Summary of Scaling Modeled Acoustic Exposure Results

6.5.1.3.1. Large-scale Animal Movement

Large-scale movements of cetaceans are driven primarily by migrations and temporally-varying prey 

concentrations (Hastie et al. 2004). Prey availability is ultimately driven by changes in production in the 

oceanic food web (Davis et al. 2001). These changes influence directly the availability of marine mammal 

prey, as is the case for plankton feeders such as Bryde’s whales. The changes also cause a delayed, but 

often amplified, abundance of larger invertebrates (e.g., squid) and/or vertebrates (e.g., fish), the food 

source of most odontocetes, such as sperm and pilot whales and smaller dolphins (e.g., Davis et al. 2001). 

The acoustically-modeled seismic surveys usually occur in deeper water (> 200 m). Five of the six 

representative cetacean species typically only occur in deeper water. Common bottlenose dolphins, 

however, have several distinct populations. One of these inhabits water deeper than 200 m and is the most 

likely population affected by seismic surveys of this Test Case. Most cetacean movement data is from 

inshore populations that have been studied more intensely and from migrating species, since information 

on movements of offshore species is sparse. None of the Test Case species is distributed evenly across the 

Gulf (Davis et al. 2001). All cetaceans surveyed in Davis et al. (2001) were found primarily in water 

depths ranging between 1200–2300 m, with the exception of common bottlenose dolphins, which also 

occurred in slightly shallower waters. There is no information indicating that any of the six modeled 

species migrate regularly on a large-scale in the Gulf; thus, large-scale movement was not integrated into 

the animal movement model. 

6.5.1.3.2. Potential Biases in the Modeling Procedure

To investigate potential systematic, and possibly unknown, biases in the modeling procedure, behavioral 

exposure estimates were determined for subsets of the Test Case simulations (see Section 6.3.2). 

Behavioral exposure estimates were determined as a function of time by finding the number of exposures 

occurring in 24 h subsets using a sliding window that advanced in 4 h increments. Trends were evident, 

particularly at Survey site A, but the trends appeared to be the consequence of survey design, such as 

changing sound fields as the vessels move into different acoustic zones. The negative trend for most 

species at Survey site A reflected the survey design in that the survey vessels start operations in deeper 

water and proceed to shallower water toward the end of the simulation. Because the acoustic propagation 
Gulf of Mexico G&G Activities Programmatic EIS D-69

range is generally longer in deeper water than at intermediate depths (see Tables 83–85 and Figures 126–

128), the ensonified volume was larger at the beginning of the simulation than at the end and more 

exposures are registered per 24 h period earlier in the simulation. This was borne out in simulations with 

the vessel tracks reversed (starting in intermediate water depths and proceeding toward deeper water). 

Fewer exposures were registered at the beginning of the simulation and more toward the end of the 

simulation as the vessels proceeded into deeper water (Figure 27). For sperm whales, there was an 

additional bias due to their general avoidance of water depths < 1000 m. The area of Survey site A began 

at a location with water depth ~ 1500 m, but proceeds to depths < 200 m. Therefore, fewer sperm whale 

animats were within exposure range of the source later in the simulation. As expected, reversing the track 

lines of the vessels (starting in shallow water and proceeding to deeper water) lead to increased behavioral 

exposure estimate rates for sperm whales over time (Figure 27b). To determine if undesired, and 

unknown, systematic biases exist in the modeling procedure, simulations were run with the source 

stationary and with no limiting bathymetric constraints (depth > 1300 m). No clear trends were found 

(Figure 28), indicating that undesired systematic biases in the modeling procedure, if present, were small 

relative to the survey design and would not affect scaling up the results in time, if applied. 

The results of the Test Case were presented as the number of animats (and animals) that were exposed to 

levels that exceed the threshold criteria for the entire simulation. SEL was accumulated throughout the 

simulation (5 days) and the maximum rms SPL exposure values were found for the whole simulation (30 

days). Animats receiving levels exceeding threshold were only counted once, but there was no mechanism 

to account for potential recovery of hearing. For this reason a smaller time period for evaluating exposure 

risk was used and the animats’ received levels were reset at the beginning of each period. The time period 

for evaluating exposure risk has not been standardized, but 24 h is often used. We compared the number 

of animats exposed to levels exceeding threshold for 24 h time periods scaled up by the number of days in 

the simulations to the number of animats exposed to levels exceeding threshold for the entire duration of 

the simulations. For metrics based on rms SPL (the NMFS criteria and the behavioral step function), 

scaling up the 24 h average estimates to 30 days (vastly) overestimates the number of animats exposed to 

levels exceeding threshold when determined over the entire simulation. This is an expected finding. It 

results because animats were commonly exposed to levels exceeding these thresholds and the relatively 

short reset period of 24 h means that individual animats were, in effect, counted several times during the 

scale up that would only have been counted once when evaluating over the entire simulation. SEL is an 

accumulation of energy, so unlike the SPL metrics evaluating over a longer period could result in more 

animats exposed to levels exceeding SEL threshold that would not when evaluated over a shorter period. 

The med-frequency species had only one or no animats above SEL threshold, so scaling trends could not 

be established for such rare events. Only Bryde’s whales (low frequency) and dwarf sperm whales (high 

frequency) had significant numbers of animats exposed to levels exceeding SEL threshold. For Bryde’s 

whales and dwarf sperm whales, scaling the 24 h average by 5 resulted in fewer animats exposed to levels 

exceeding threshold than the number of animats exposed to levels exceeding threshold for the entire 

simulation. The percentage shortfall, however, was much less than the overestimates seen in the NMFS 

criteria and behavioral step function in the 30 day simulations. In addition, it was observed that scaling 

the 24 h zero-to-peak SPL exceedance estimates could also result in a modest shortfall. Animats 

exceeding zero-to-peak SPL were only counted once per evaluation period and energy did not 

accumulate, so scaling up from a short reset period should overestimate the number of animats exposed to 

levels exceeding threshold. When using an overlap, the sliding window approach under-samples the edge 

time periods compared to the central time periods. When the number of animats exposed to levels 

exceeding the zero-to-peak SPL and SEL thresholds for 24 h was scaled up by 4 and compared to number 

of animats exposed to levels exceeding these thresholds during a 4 day period in the middle of the 5 day 

simulation, the scaled estimates again overestimated the longer time window results. (Except in the case 

of the sperm whales, which was an artifact of rounding a small number.) These edge effects of the sliding 

window sampling were small and exaggerated in the Test Case because the surveys start an end at 

extreme locations of the sound field and animal locations. Starting and ending surveys at the extremes of 
D-70 Acoustic Propagation and Marine Mammal Exposure Modeling

sound fields and animal depth restrictions is not typical, so the edge effects were not expected to 

significantly affect results.

6.5.1.3.3. Scaling Short-duration Simulations for Long-duration Operations

As discussed previously, large-scale animal movements can affect the real-world densities that are used to 

adjust model (animat) exposure estimates. If the simulation is short relative to the large-scale movement 

(or behavioral change), there is little effect on the estimated exposures (i.e., provided the behavioral states 

and acoustic fields remain relatively constant, exposure estimates from short-duration simulations can be 

adjusted for different seasonal density estimates). 

Systematic trends in the modeling procedure were evident, indicating that survey design can affect 

exposure estimates when scaling is used. The minimum duration of a simulation should, therefore, 

include all of the acoustic environments likely to be encountered during the operation. For example, if a 

survey will range from deep to shallow water, then it is not sufficient to only simulate operations in deep 

water (unless it is known that exposures in deep water are always greater than in shallow water and a 

conservative estimate of the exposures is desired). When the evaluation period (or reset time) is short, 

e.g., 24 h, the simulation should still include all acoustic environments, and exposures should be 

presented as a function of time or averaged to get an expected value during the evaluation period. 

Our suggested procedure for estimating exposures for long-duration surveys (i.e., three months):

1. Identify the shortest large-scale animal movement time-period (e.g., seasonal migration).

2. Identify acoustic environments over which the survey will occur (e.g., shallow, slope, deep, and 

associated geoacoustic parameters).

3. Identify the minimum period of validity for the acoustic model (e.g., month due to changing sound 

velocity profile).

4. Break the survey into parts that are shorter in duration than both large-scale animal movement times 

and the period of acoustic model validity. 

5. Create animal movement simulations for acoustic exposure with adequate duration to meaningfully 

sample the exposure-estimating parameter (e.g., if a 24 h reset period is used then enough samples 

should be obtained to get a reliable mean value given the various acoustic environments).

6. If the simulation time is less than the duration of the survey parts determined in Step 4, then scale the 

results by the ratio of survey duration to simulation time (e.g., if the simulation time is one week, but 

the survey division is 28 days, then multiply the simulation exposure results by four).

7. Sum, or aggregate, the results from the survey parts to calculate exposures for the entire survey. 

6.5.2. Test Scenario 2: Analysis of Uncertainty in Acoustic and Animal 

Modeling

The process of using computer models to predict acoustic effects on marine mammals requires making 

simplifying assumptions about oceanographic parameters, seabed parameters, and animal behaviors. 

These assumptions carry some uncertainty, which may lead to uncertainty in the form of variance or error

in individual model outputs and in the final estimates of marine mammal acoustic exposures. For 

example, acoustic propagation models assume a specific shape of the sound speed profile in the ocean 

(speed of sound versus depth) for each season. We know, however, that the real sound speed profile 

regularly changes and that substantial variation within a season is possible. The assumption that a single 

profile represents the environment through a full season approximates real-world cases, but can, to some 

degree, cause errors. The uncertainty in model outputs caused by approximations like this can be 
Gulf of Mexico G&G Activities Programmatic EIS D-71

investigated by examining how much the outputs change when the inputs are purposely offset. This type 

of investigation, referred to as parametric uncertainty analysis, provides a means to characterize the 

accuracy, or uncertainty, of the model results in light of errors in model inputs. It can also be used to 

characterize the expected variability in model results due to natural variations in some of the input 

parameters.

The exposure calculations used for biological effects assessment are performed using an animal 

movement model that simulates and tracks individual animals in space and time through the sound field. 

As with the acoustic model, the animat movement model requires inputs that approximate real-world 

values. In fact, the acoustic model results are one of the inputs to the animat model, and those inherently 

have uncertainty, as described above. The animat model outputs consequently also include uncertainty. 

By using a resampling technique, we can quantify the effects of uncertainty in exposure estimates due to 

uncertainty in acoustic and animal movement models.

6.5.2.1. Acoustic Modeling Uncertainty

Acoustic exposure estimates require knowledge of the sound fields to which marine mammals are 

exposed. Here we are concerned with estimating exposures from geotechnical and geophysical survey 

operations. Sound field modeling consists of two major stages: source characterization and acoustic 

propagation modeling. The uncertainty that arises in both of these stages is considered in the following 

sections. 

6.5.2.1.1. Source Characterization Modeling Uncertainty

Characteristics of sound sources, such as the sound levels in different frequency bands and the directivity 

of the sources, were used with acoustic propagation modeling to determine quantify the received sound 

levels to which marine mammals are exposed. There were uncertainties associated with the source, such 

as variations in source level during operation, and uncertainty associated with a source model’s predicted 

levels. Field measurements of an operating source that has been modeled can be used to determine the 

overall uncertainty associated with the source level modeling. 

The sound source used in the Test Case (Section 6.3.1.1) was a generic 8000 in3 airgun array. JASCO’s 

airgun array source model (AASM) was used to characterize the far-field emission levels and directivity 

of the source. AASM is a numerical model that simulates the fluid dynamics and sound radiation of a 

collection of high-pressure air bubbles. As with other airgun models, AASM incorporates a number of 

simplifying assumptions about the underlying physics to make the numerical calculation tractable. 

Among these assumptions are that the bubbles are perfectly spherical and that the sound field radiated by 

each airgun is isotropic and point-like, which are only approximately true in practice. Furthermore, the 

physical model employed by AASM includes free parameters, which govern the rate of air injected into 

the bubble and the rate of heat transfer between the bubble and the surrounding water. The values of these 

free parameters are determined by fitting model predictions to the measured signatures for a large 

collection of airguns (MacGillivray 2006). Errors in AASM thus originate from two different sources: the 

approximations employed in the underlying physical model, and the experimental uncertainties in the 

model parameterization of the specific airguns.

Uncertainty associated with these errors can be estimated by comparing model predictions to acoustic 

field measurements of airgun arrays. Such comparisons are complicated because the source levels 

computed by the model must, by definition, be measured in the far field of the array. Since a model of 

sound propagation must be used to calculate received levels in the far field, it is thus impossible to 

completely decouple uncertainties in the source model from uncertainties in the sound propagation model. 

Nonetheless, uncertainties can be estimated from field data by comparing model predictions with sound 

level measurements at relatively short range, where propagation loss is reasonably well constrained. 
D-72 Acoustic Propagation and Marine Mammal Exposure Modeling

Studies comparing AASM predictions with seismic array measurements have been carried at a number of 

sites, including in the Chukchi Sea (McPherson et al. 2005), the Beaufort Sea (Matthews and 

MacGillivray 2013), and offshore British Columbia (Austin et al. 2012). These studies have shown that 

the modeled SELs are typically within 3 dB of the measured values.

6.5.2.1.2. Acoustic Propagation Modeling Uncertainty

Transmission of sound is determined by the characteristics of the media (e.g., air, water, and seafloor 

sediments) in which that sound propagates. The acoustics model used here accepts several parameters 

describing the ocean environment in which sound propagation is modeled. The key inputs are sound 

speed variation with depth (sound speed profile), seabed composition and layering, and bathymetric 

variation between each sound source and receiver. 

Uncertainty in acoustic environmental parameters leads to uncertainty in model outputs. The relationship 

between the input parameters and the output is complex and cannot be expressed with a simple rule. An 

empirical approach was taken to investigate how uncertainty in the inputs affects the modeled acoustic 

field. Sound fields were modeled using mean parameter values and a combination of parameter values, 

chosen from within their measured ranges, expected to maximize sound propagation. These sound fields, 

mean and maximum-propagation, were subtracted to determine the difference, which indicates the range 

of errors due to uncertainty in inputs. Three acoustic zones were analyzed: Shelf, Slope, and Deep. Each 

zone was modeled for three propagation directions: downslope, upslope, and along-slope. The upslope 

and downslope directions led respectively from the source into shallower and deeper waters. The alongslope direction followed a path of (approximate) constant depth (bathymetric contour) away from the 

source. 

6.5.2.1.3. Sound Speed Profiles

A sound speed profile represents the water sound speed as a function of depth. In general, sound speed 

increases with increasing temperature and salinity. It also increases with increased hydrostatic pressure, 

so there is a systematic increase with depth. Sound speed profiles for the modeled sites were derived from 

temperature and salinity profiles from the U.S. Naval Oceanographic Office’s Generalized Digital 

Environmental Model V 3.0 (GDEM, Teague et al. 1990, Carnes 2009). GDEM provides an ocean 

climatology of temperature and salinity for the world’s oceans on a latitude-longitude grid with 0.25° 

resolution, with a temporal resolution of one month, based on global historical observations from the U.S. 

Navy’s Master Oceanographic Observational Data Set (MOODS). The climatology profiles include 78 

fixed depth points to a maximum depth of 6800 m (where the ocean is that deep), including 55 standard 

depths between 0 and 2000 m. The GDEM temperature-salinity profiles were converted to sound speed 

profiles according to the equations of Coppens (1981). 

( )( )

[ ( )]

10

0026.01 cos 2

1000

18.03.16

009.0126.0333.1 35

23.021.57.4505.1449),,,(

2

2

2 3

T

t

z Z

ZZ

Stt

STzc ttt

=

−= φ

+=∆

+−+ ∆+−

−−+=φ

(19) 

where z is water depth (m), T is water temperature (°C), S is salinity (psu), and φ is latitude (radians). 
Gulf of Mexico G&G Activities Programmatic EIS D-73

Sound speed profiles were obtained for three depth zones (Table 28) along the study line, south of 

Louisiana (Figures 29–31). Surface sound ducts, or channels, occur when the sound speed increases with 

depth below the surface leading to a positive sound speed gradient. This can occur physically when 

surface waters are cooler than underlying waters. Sounds propagating in the gradient are refracted upward 

and can become partially trapped near the surface, leading to enhanced sound propagation and higher 

near-surface sound levels. A weak surface sound channel is present during some months of the year in the 

Gulf of Mexico, with variations in the gradient and depth of the channel based on the month and zone. To 

account for varying sound speed profiles throughout the year, seasons were defined for each zone based 

on the sound speed at the surface and the gradient and depth of the sound channel in the top 200 m 

(Table 29). A negative gradient indicates a more downward refracting environment, whereas a positive 

gradient at the surface indicates a surface sound channel that can propagate sound to longer ranges. 

Table 28. Depth zones along the study line.

Zone Depths (m) Range–Latitude (°N) Range–Longitude (°W)

Shelf 25–200 28–28.75

Slope 200–2000 26.5–28 89–91

Deep > 2000 24.5–26.5

Table 29. Modeled seasons and their characteristics.

Zone Season Period

Month used to acquire 

representative sound 

speed profile

Seasonal characteristics

Shelf 1 Dec–Mar Feb Strong sound channel at depths 

up to 50–75 m below surface

2 Apr–Nov Sep Weak to no sound channel in 

top 20–40 m

Slope 1 Jul–Sep Aug Weak to no sound channel

2 Oct–Jun Mar Downward refracting at surface

Deep 1 Jan–Dec May Very weak to no sound channel 

throughout year
D-74 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 29. The Shelf zone (28.5° N, 90° W): Mean monthly sound speed profiles, separated into 

Seasons 1 (left) and 2 (right). Bolded profiles indicate average sound speed profile used for 

the season. Derived from data obtained from GDEM V 3.0 (Teague et al. 1990, Carnes 2009). 
Gulf of Mexico G&G Activities Programmatic EIS D-75

Figure 30. The Slope zone (27.25° N, 90° W): Mean monthly sound speed profiles, separated into 

Seasons 1 (left) and 2 (right). Bolded profiles indicate average sound speed profile used for 

the season. Derived from data obtained from GDEM V 3.0 (Teague et al. 1990, Carnes 2009). 

 

Figure 31. Deep zone (25.5° N, 90° W): Mean monthly sound speed profiles. Bolded profile indicates 

average sound speed profile used for the season. Derived from data obtained from GDEM V 

3.0 (Teague et al. 1990, Carnes 2009). 
D-76 Acoustic Propagation and Marine Mammal Exposure Modeling

To determine uncertainty in the acoustic field propagation due to variability of the sound speed profiles 

within in each season, original CTD casts, containing temperature and salinity information, were 

extracted from NOAA’s database. Spatial limits from W89° to W91° were applied during database query. 

Temperature and salinity data were processed to obtain sound speed profiles using Equation 19. 

All sound speed profiles were plotted by month separately for each zone: Shelf, Slope, and Deep. 

Monthly groups of sound speed profiles were combined into seasons based on similarity of the features: 

variability within each month and presence of the surface sound channel.

Two periods (seasons) were distinguished for the Shelf zone: 

• Dec–Mar

• Apr–Nov

Two periods (seasons) were distinguished for the Slope zone:

• Jul–Sep

• Oct–Jun 

In the Deep zone, we established that the separation into seasons is unwarranted because variability of the 

sound speed profiles throughout the year is not significantly larger than the variability within individual 

months. 

In each group of sound speed profiles, 16% of the profiles with the highest gradient in the top 25 m (with 

the most pronounced sound channel) were removed to avoid the most extreme conditions, for which the 

probability of occurrence is low. This step was taken to omit profiles that may have been distorted by 

measurement system temperature settling. The remaining profiles are plotted together in Figures 32–34. 

The maximum-propagation sound speed profile was chosen from the remaining profiles to reproduce the 

maximum gradient. The median sound speed profiles were obtained from GDEM profile of the central 

month of the season as identified in Table 29. 

The maximum-propagation scenario sound speed profiles for both seasons in the Shelf zone exhibit a 

surface sound channel extending to 40 m depth. The difference between the sound speed at the top 

(surface) and bottom (at 40 m depth) of the channel is 15 m/s during Season 1 and 10 m/s during Season 

2. In the Slope zone, the occurrence of the surface sound channel exists only during Season 1. Season 2 in 

the Slope zone is characterized by a small negative gradient in the sound speed profile over the top 75 m 

of the water column, so no surface channel exists. Data for the Deep zone show little variability of the 

shape of the sound speed profile throughout the year. A single season was, therefore, defined and used for 

modeling in that zone. 
Gulf of Mexico G&G Activities Programmatic EIS D-77

Figure 32. Shelf zone: Modeled average and maximum-propagation sound speed profiles based on 

variations in CTD cast data for Seasons 1 (left) and 2 (right). Raw profiles are derived from 

NOAA Gulf of Mexico CTD cast data and mean monthly profiles are derived from GDEM V 

3.0 (Teague et al. 1990, Carnes 2009). 

Figure 33. Slope zone: Modeled average and maximum-propagation sound profiles based on variations in 

CTD cast data for Seasons 1 (left) and 2 (right). Raw profiles are derived from NOAA Gulf 

of Mexico CTD cast data and mean monthly profiles are derived from GDEM V 3.0 (Teague 

et al. 1990, Carnes 2009). 
D-78 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 34. Deep zone: Modeled average and maximum-propagation sound speed profiles based on 

variations in CTD cast data. Raw profiles are derived from NOAA Gulf of Mexico CTD cast 

data and mean monthly profiles are derived from GDEM (Teague et al. 1990, Carnes 2009). 

6.5.2.1.4. Sound Speed Profile Results

The analysis of acoustic field uncertainty due to sound speed profile uncertainty was performed by 

calculating and examining the differences in acoustic fields between the maximum-propagation and 

median case sound speed profiles. The source used for these runs was the 8000 in3 airgun array, at 8 m 

depth. All model runs for this analysis used geoacoustic (seabed parameter) profiles with median 

reflectivity at all three zones. The comparisons performed for the Shelf and Slope zones were made for 

both of the seasonal sound speed profiles of those zones. Only the one season and a single corresponding 

sound speed profile exist for the Deep zone. 

Shelf zone: December–March

Figure 35. Shelf zone, Dec–Mar: Received SEL acoustic field using conservative (enhanced propagation) 

sound speed profile and median reflectivity geoacoustic parameters. Downslope direction.
Gulf of Mexico G&G Activities Programmatic EIS D-79

Figure 36. Shelf zone, Dec–Mar: Received SEL acoustic field using median sound speed profile and 

median reflectivity geoacoustic parameters. Downslope direction.

Figure 37. Shelf zone, Dec–Mar: Differential acoustic field due to variation in the sound speed profile.

Downslope direction.

Shelf zone: April–November

Figure 38. Shelf zone, Apr–Nov: Received SEL acoustic field using conservative sound (enhanced 

propagation) speed profile and median reflectivity geoacoustic parameters. Downslope 

direction.
D-80 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 39. Shelf zone, Apr–Nov: Received SEL acoustic field using median sound speed profile and 

median reflectivity geoacoustic parameters. Downslope direction. 

Figure 40. Shelf zone, Apr–Nov: Differential acoustic field due to variation in the sound speed profile.

Downslope direction.

Slope zone: July–September 

Figure 41. Slope zone, Jul–Sep: Received SEL acoustic field using conservative sound speed profile and 

median reflectivity geoacoustic parameters. Downslope direction.
Gulf of Mexico G&G Activities Programmatic EIS D-81

Figure 42. Slope zone, Jul–Sep: Received SEL acoustic field using median sound speed profile and 

median reflectivity geoacoustic parameters. Downslope direction.

Figure 43. Slope zone, Jul–Sep: Differential acoustic field due to variation in the sound speed profile.

Downslope direction.

Slope zone: October–June

Figure 44. Slope zone: Received SEL acoustic field sing conservative sound speed profile and median 

reflectivity geoacoustic parameters. Downslope direction.
D-82 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 45. Slope zone, Oct–Jun: Received SEL acoustic field using median sound speed profile and 

median reflectivity geoacoustic parameters. Downslope direction.

Figure 46. Slope zone, Oct–Jun: Differential acoustic field due to variation in the sound speed profile.

Downslope direction.

Deep zone

Figure 47. Deep zone: Received SEL acoustic field using conservative sound speed profile and median 

reflectivity geoacoustic parameters. Downslope direction.
Gulf of Mexico G&G Activities Programmatic EIS D-83

Figure 48. Deep zone: Received SEL acoustic field using median sound speed profile and median 

reflectivity geoacoustic parameters. Downslope direction.

Figure 49. Deep zone: Differential acoustic field due to variation in the sound speed profile. Downslope 

direction.

In each zone, the acoustic field was propagated in three directions (downslope, upslope, and along slope). 

For each direction, the range to the rms SPL 160 dB re 1 μPa (153 dB re 1 μPa·s2 SEL) threshold was 

estimated based on the maximum-propagation scenario acoustic field in the comparison pair. The average 

difference and standard deviation were calculated based on the differences at locations within a 5 km 

horizontal × 20 m deep box along the radials starting at the threshold range. The 20 m vertical extent was 

selected to emphasize the depths at which the animals spend much of their time. Table 30 shows the 

calculated average differences between the maximum-propagation and median case scenarios, and the 

distance at which the 160 dB re 1 μPa rms SPL threshold occurs. 
D-84 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 30. Acoustic field differences between maximum-propagation and average sound speed profile conditions.

Column “R” shows the maximum distance in kilometers of 160 dB re 1 μPa rms SPL threshold exceedance. The 

Median (σ) column shows the median difference and standard deviation in decibels, over a range-depth zone 

containing many receivers, near the 160 dB re 1 μPa threshold location.

Direction

Shelf zone Slope zone Deep zone

Dec-Mar Apr-Nov Jul-Sep Oct-Jun Jan-Dec

R 

(km)

Median 

(σ) (dB)

R 

(km)

Median 

(σ) (dB)

R 

(km)

Median 

(σ) (dB)

R 

(km)

Median 

(σ) (dB)

R 

(km)

Median 

(σ) (dB)

Downslope 30.6* 14.9 (1.0) 22.6 10.5 (2.7) 11.5 0.7 (0.6) 14.1 0.2 (0.5) 10 0.3 (0.3)

Along 

slope 23.5 7.0 (1.2) 12.2 5.7 (2.8) 8.8 2.0 (1.8) 8.3 0.7 (0.9) 6.7 −0.1 (0.3)

Upslope 14.3 5.0 (1.3) 9.2 6.5 (1.8) 7.7 1.2 (0.8) 8.9 0.4 (0.4) 9.4 3.8 (2.5)

* 163 dB re 1 μPa rms SPL threshold was used for this scenario since 160 dB re 1 μPa rms SPL threshold was beyond 50 km 

modeled range.

6.5.2.1.5. Geoacoustics

Geoacoustic parameters describe the acoustic properties of the seabed, including sound speeds in various 

layers. JASCO’s MONM-RAM model, a parabolic-equation-based acoustic propagation model, was used 

to calculate transmission loss from the source to locations within a vertical plane in the water column. 

MONM-RAM assumes a single geoacoustic profile of the seafloor for the entire modeled area (see 6.2.3

for required input parameters). 

Figure 50. The map of dominant type for the surficial sediments (NOS 2013) and location of the drill 

wells in the Gulf of Mexico.
Gulf of Mexico G&G Activities Programmatic EIS D-85

Two geoacoustic profiles—(1) the most likely (median) propagation conditions and (2) an extreme case 

of a more reflective bottom—were determined for each zone (Shelf, Slope, and Deep). The two profiles 

within each zone were based on similar sediment types, but the more-reflective variant was achieved by 

increasing the grain size and/or porosity of the sediment layers relative to the median case values.

The NOAA/NOS and USCGS Seabed Descriptions from Hydrographic Surveys (National Ocean Service 

2013) were used to define the surficial sediment types for the specific zone (Figure 50). The well log data 

from DSDP/ODP/IODP legs were used to estimate the change of the porosity with depth. Sediment grainshearing model (Buckingham 2005) was used to compute the acoustic properties of the sediments based 

on the porosity data and grain-size estimates. The grain size of the sediments is usually indicated by the 

parameter, φ, using an inverse logarithmic scale. From coarsest to finest, sand has φ from 0 to 4, for silt φ

varies from 4 to 8, and for clay φ varies from 8 to 10. 

The top layers of the seafloor in the Gulf of Mexico are represented by layers of unconsolidated 

sediments with the thickness of at least several hundred meters. The grain size of the surficial sediments 

follow the general trend for the sedimentary basins: the grain size of the deposited sediments decreases 

with the distance from the shore. The general surficial bottom type varies by zones: for the Shelf zone it 

was sand, for the Slope zone it was silt, and for the Deep zone it was clay.

The three sets of geoacoustic parameters for each zone, Shelf, Slope, and Deep, are presented in 

Tables 31, 32, and 33, respectively.

Table 31. Shelf zone: Median and higher reflectivity geoacoustic profiles. Sand is the dominant surficial sediment. 

Depth below the 

seafloor (m)

Median reflectivity (φ=2) Higher reflectivity (φ=1)

Porosity 

(%)

Rho 

(g/cm3)

VP 

(m/s)

Porosity 

(%)

Rho 

(g/cm3)

VP 

(m/s)

1 65 1.61 1610 60 1.70 1660

20 60 1.70 1900 55 1.78 2040

50 55 1.78 2090 50 1.87 2290

200 50 1.87 2500 45 1.96 2500

600 40 2.04 2500 40 2.04 2500

Table 32. Slope zone: Lower, median, and higher reflectivity geoacoustic profiles. Silt is the dominant surficial 

sediment.

Depth below the 

seafloor (m)

Lower reflectivity (φ=7) Median reflectivity (φ=5) Higher reflectivity (φ=4)

Porosity 

(%)

Rho 

(g/cm3)

VP 

(m/s)

Porosity 

(%)

Rho 

(g/cm3)

VP 

(m/s)

Porosity 

(%)

Rho 

(g/cm3)

VP 

(m/s)

1 80 1.35 1490 75 1.44 1515 75 1.44 1530

20 65 1.61 1580 60 1.7 1670 60 1.7 1720

50 60 1.7 1640 60 1.7 1750 60 1.7 1830

200 50 1.87 1790 50 1.87 1970 50 1.87 1870

600 40 2.04 1980 40 2.04 2260 40 2.04 2040
D-86 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 33. Deep zone: Lower, median, and higher reflectivity geoacoustic profiles. Clay is the dominant surficial 

sediment.

Depth below the 

seafloor (m)

Lower reflectivity (φ=9) Median reflectivity (φ=8) Higher reflectivity (φ=8)

Porosity 

(%)

Rho 

(g/cm3)

VP

(m/s)

Porosity 

(%)

Rho 

(g/cm3)

VP

(m/s)

Porosity 

(%)

Rho 

(g/cm3)

VP

(m/s)

1 75 1.44 1460 70 1.52 1472 60 1.70 1494

20 65 1.61 1520 60 1.70 1560 55 1.78 1570

50 60 1.70 1560 55 1.78 1610 50 1.87 1640

200 55 1.78 1650 50 1.87 1720 45 1.96 1750

600 45 1.96 1780 40 2.04 1890 40 2.04 1890

6.5.2.1.6. Geoacoustic Results 

To analyze acoustic field uncertainty due to differences in the geoacoustic properties of the sea bottom, 

the respective median sound speed profiles were used to model in each zone. Sound fields were generated 

using the median and high reflectivity geoacoustic parameters (as defined above) and the resulting sound 

fields subtracted to determine the differences. The comparison was conducted separately for two seasons 

each in the Shelf and Slope zones and for the one season representing the entire year in the Deep zone.

Shelf zone: December–March

Figure 51. Shelf zone, Dec–Mar: Received SEL acoustic field using median sound speed profile and high 

reflectivity geoacoustic parameters. Downslope direction.

Figure 52. Shelf zone, Dec–Mar: Received SEL acoustic field using median sound speed profile and 

median reflectivity geoacoustic parameters. Downslope direction.
Gulf of Mexico G&G Activities Programmatic EIS D-87

Figure 53. Shelf zone, Dec–Mar: Differential acoustic field due to variation in the bottom geoacoustic 

parameters. Downslope direction.

Shelf zone: April–November

Figure 54. Shelf zone, Apr–Nov: Received SEL acoustic field using median sound speed profile and high 

reflectivity geoacoustic parameters. Downslope direction.

Figure 55. Shelf zone, Apr–Nov: Received SEL acoustic field using median sound speed profile and 

median reflectivity geoacoustic parameters. Downslope direction.
D-88 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 56. Shelf zone, Apr–Nov: Differential acoustic field due to variation in the bottom geoacoustic 

parameters. Downslope direction.

Slope zone: July–September 

Figure 57. Slope zone, Jul–Sep: Received SEL acoustic field using median sound speed profile and high 

reflectivity geoacoustic parameters. Downslope direction.

Figure 58. Slope zone, Jul–Sep: Received SEL acoustic field using median sound speed profile and 

median reflectivity geoacoustic parameters. Downslope direction.
Gulf of Mexico G&G Activities Programmatic EIS D-89

Figure 59. Slope zone, Jul–Sep: Differential acoustic field due to variation in the bottom geoacoustic 

parameters. Downslope direction.

Slope zone: October–June

Figure 60. Slope zone, Oct–Jun: Received SEL acoustic field using median speed profile and high 

reflectivity geoacoustic parameters. Downslope direction.

Figure 61. Slope zone, Oct–Jun: Received SEL acoustic field using median sound speed profile and 

median reflectivity geoacoustic parameters. Downslope direction.
D-90 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 62. Slope zone, Oct–Jun: Differential acoustic field due to variation in the bottom geoacoustic 

parameters. Downslope direction.

Deep zone

Figure 63. Deep zone: Received SEL acoustic field using median sound speed profile and high reflectivity 

geoacoustic parameters. Downslope direction.

Figure 64. Deep zone: Received SEL acoustic field using median sound speed profile and median 

reflectivity geoacoustic parameters. Downslope direction.
Gulf of Mexico G&G Activities Programmatic EIS D-91

Figure 65. Deep zone: Differential acoustic field due to variation in the bottom geoacoustic parameters. 

Downslope direction.

As was done for the sound velocity profiles, the acoustic field in each zone was propagated in three 

directions (downslope, upslope, and along-slope), and for each direction the range to the 160 dB re 1 μPa 

rms SPL (153 dB re 1 μPa·s2 SEL) threshold was estimated. The average difference and standard 

deviation were calculated based on the differences for individual receivers within a 5 km horizontal × 

20 m deep box starting at the threshold range. The 20 m vertical extent was selected to emphasize the 

depths at which animals spend much of their time. Table 34 shows the calculated average differences 

between the maximum-propagation and median case scenarios, and the distance at which the 160 dB re 

1 μPa rms SPL threshold occurs.

Table 34. Acoustic field differences between reflective and average geoacoustic conditions. Column “R” shows the 

maximum distance in kilometers of 160 dB re 1 μPa rms SPL threshold exceedance. Median (σ) column shows the

median difference and standard deviation in decibels, over a range-depth zone containing many receivers, near the 

160 dB re 1 μPa threshold location.

Direction

Shelf zone Slope zone Deep zone

Dec-Mar Apr-Nov Jul-Sep Oct-Jun Jan-Dec

R 

(km)

Median 

(σ) (dB)

R 

(km)

Median 

(σ) (dB)

R 

(km)

Median 

(σ) (dB)

R 

(km)

Median 

(σ) (dB)

R 

(km)

Median 

(σ) (dB)

Downslope 24.1 −0.9 (0.7) 18.6 3.4 (1.7) 17.3 2.7 (1.1) 18.5 2.2 (1.2) 9.6 3.8 (1.5)

Along 

slope 16.5 1.3 (2.2) 11.6 3.5 (2.8) 8.5 3.4 (2.2) 10.9 1.8 (1.1) 6.8 4.0 (1.2)

Upslope 10.7 1.1 (1.3) 8.0 3.4 (1.3) 9.4 2.4 (1.0) 9.4 1.8 (0.9) 9.7 3.1 (1.9)

* 156 dB re 1 μPa rms SPL threshold was used for this scenario since 153 dB re 1 μPa rms SPL threshold was beyond 50 km 

modeled range.

6.5.2.1.7. Bathymetry

Water depth and local bathymetric features affect sound propagation. There is uncertainty associated with 

bathymetric accuracy and uncertainty in using sound fields generated for a specific location to represent a 

larger area. Here, a comparison is developed to show the variation in received levels with both the water 

depth at the source and with local features such as hills, troughs, and local slopes. 

The purpose of this analysis was to delineate how acoustic propagation differences due to variations in 

bathymetry result in variations in the acoustic field in each of several water depth regimes (shallow, slope, 

deep vs. downslope, along-slope, upslope). The bathymetry variation in any one regime was represented 

as a pair of modeling sites at different, but nearby, water depths. The difference in the acoustic field 

modeled at these paired sites is reported as a mean and standard deviation over range and receiver depth. 

The bottom topography variation differences that exist between each paired site are included in the 
D-92 Acoustic Propagation and Marine Mammal Exposure Modeling

analysis. This is different from a sensitivity analysis that would examine variations in the acoustic field 

based on small perturbations in modeling bathymetry at individual modeling sites. As such, the analysis 

reported here estimates the uncertainty in the acoustic field due to bathymetric variations that occur 

within a given acoustic regime. This is directly relevant to the Phase II study because modeling results 

from one site were used as a proxy for the acoustic field produced by a source at various locations within 

a given modeling regime represented by that site. 

6.5.2.1.8. Bathymetry Results 

To analyze acoustic field uncertainty due to bathymetry, the acoustic fields calculated for the exposure 

modeling were used. Modeling sites were selected at 25, 75, and 150 m depth (Shelf zone), 300, 500, 750, 

1000, and 1500 m depth (Slope zone), and 2000 and 2500 m depth (Deep zone). The sound propagation 

modeling for the analysis was performed for Season 1 (winter) sound speed profile and median 

reflectivity geoacoustic profile.

Acoustic fields at pairs of water depths were compared: 

• 25 and 75 m 

• 75 and 150 m 

• 300 and 500 m 

• 500 and 750 m 

• 750 and 1000 m 

• 1000 and 1500 m 

• 2000 and 2500 m 

The differential field was calculated by subtracting the received levels of the acoustic field at deeper site 

from the received levels at shallower site. The positive values of the differential field indicate that the 

received level at specific distance from the source and depth from the sea surface was greater for the site 

with shallower water depth at the source.

Shelf zone: 25 m to 150 m 

Figure 66. Shelf zone: The source when positioned at water column depth of 25 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 
Gulf of Mexico G&G Activities Programmatic EIS D-93

Figure 67. Shelf zone: The source when positioned at water column depth of 75 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 

Figure 68. Shelf zone: The source when positioned at water column depth of 150 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 

Figure 69. Shelf zone: Differential acoustic field for the source when positioned at water column depths 

of 25 and 75 m: Differential acoustic field due to variation of the water depth at the source.

Cross-slope direction. 
D-94 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 70. Shelf zone: Differential acoustic field for the source when positioned at water column depths 

of 75 and 150 m: Differential acoustic field due to variation of the water depth at the source.

Cross-slope direction. 

Slope zone: 300 m to 1500 m 

Figure 71. Slope zone: The source when positioned at water column depth of 300 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 

Figure 72. Slope zone: The source when positioned at water column depth of 500 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 
Gulf of Mexico G&G Activities Programmatic EIS D-95

Figure 73. Slope zone: The source when positioned at water column depth of 750 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 

Figure 74. Slope zone: The source when positioned at water column depth of 1000 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 

Figure 75. Slope zone: The source when positioned at water column depth of 1500 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 
D-96 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 76. Slope zone: Differential acoustic field for the source when positioned at water column depths 

of 300 and 500 m. Cross-slope direction. 

Figure 77. Slope zone: Differential acoustic field for the source when positioned at water column depths 

of 500 and 750 m. Cross-slope direction. 

Figure 78. Slope zone: Differential acoustic field for the source when positioned at water column depths 

of 750 and 1000 m. Cross-slope direction.
Gulf of Mexico G&G Activities Programmatic EIS D-97

Figure 79. Slope zone: Differential acoustic field for the source when positioned at water column depths 

of 1000 and 1500 m. Cross-slope direction. 

Deep zone: 2000 m to 2500 m 

Figure 80. Deep zone: The source when positioned at water column depth of 2000 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 

Figure 81. Deep zone: The source when positioned at water column depth of 2500 m: Received SEL 

acoustic field using Season 1 sound speed profile and median reflectivity geoacoustic 

parameters. Cross-slope direction. 
D-98 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 82. Deep zone: Differential acoustic field for the source when positioned at water column depths 

of 2000 and 2500 m Cross-slope direction. 

For each scenario, the acoustic field was propagated in three directions: downslope, upslope, and alongslope. Two sites at adjacent water depths were compared. The average difference and standard deviation 

were calculated for a set of ranges from the source: 500, 1000, 2000, 5000, and 10,000 m. The received 

levels at the individual receivers within the selected ranges and the top 20 m were considered. The 20 m 

vertical extent was selected to emphasize the depths at which the animals spend much of their time. 

Table 35 provides the calculated average differences in the selected volume between the acoustic fields 

calculated for the adjacent sites.
Gulf of Mexico G&G Activities Programmatic EIS D-99

Table 35. Acoustic field uncertainty due to variations in the water depth at the source. Median value and σ (number 

in brackets) are provided in dB for various averaging ranges from the source and direction of the propagation.

Range/

Direction

Shelf zone Slope zone Deep zone

25–75 m 75–150 m 300–500 m 500–750 m 750–1000 m 1000–1500 m 2000–2500 m

500 m 

Downslope 3.8 (2.6) 3.6 (2.8) 1.2 (1.3) 0.6 (0.8) 0.4 (0.8) 0.1 (0.5) 0.3 (0.7) 

Along slope 4.4 (4.1) 3.8 (4.5) 0.9 (1.7) 0.5 (1.3) 0.3 (1.1) 0.2 (0.8) −0.0 (0.1) 

Upslope 3.8 (2.9) 3.9 (3.1) 1.4 (1.3) 0.8 (1.0) 0.3 (0.7) 0.4 (0.9) −0.1 (0.4) 

1000 m 

Downslope 2.9 (2.2) 2.3 (2.6) 0.9 (1.3) 1.3 (1.0) 1.1 (1.1) 1.2 (1.4) 1.6 (1.9) 

Along slope 3.4 (3.5) 3.0 (3.8) 0.6 (1.9) 0.8 (1.9) 0.8 (1.6) 0.6 (1.9) 0.3 (1.3) 

Upslope 2.8 (2.5) 2.3 (2.9) 1.5 (1.3) 1.5 (1.2) 1.0 (1.1) 1.8 (1.8) −0.1 (1.2) 

2000 m 

Downslope 1.7 (2.2) 1.4 (2.2) 3.4 (3.3) 1.3 (1.0) 1.0 (1.0) 1.7 (1.8) 1.8 (3.2) 

Along slope 2.4 (3.2) 1.9 (3.5) 4.2 (4.6) 0.9 (2.1) 0.6 (1.7) 0.8 (2.4) −0.5 (2.2) 

Upslope 1.7 (2.2) 1.0 (2.6) 3.7 (3.1) 1.5 (1.3) 1.0 (0.9) 2.3 (3.2) 1.0 (2.2) 

5000 m 

Downslope 0.0 (2.2) 0.5 (2.0) 0.3 (3.8) 1.5 (2.7) 1.8 (2.4) 4.9 (5.2) 2.2 (3.3) 

Along slope 1.0 (3.0) 0.8 (3.3) 2.1 (4.4) 2.9 (3.6) 2.8 (3.4) 3.5 (3.8) 1.0 (2.9) 

Upslope −0.8 (3.1) −0.3 (2.2) 0.8 (3.5) 1.8 (2.4) 1.8 (2.7) 4.1 (5.0) 0.4 (4.0) 

10000 m 

Downslope −0.6 (1.9) 0.5 (1.7) −1.2 (3.9) −0.1 (2.8) 1.0 (2.2) 4.9 (4.2) 1.4 (3.6) 

Along slope −1.2 (3.8) 0.4 (3.5) 0.0 (4.2) 1.4 (3.8) 2.4 (3.6) 1.9 (5.4) 2.0 (4.3) 

Upslope −3.2 (4.3) −0.6 (1.9) −1.4 (3.8) 0.4 (2.6) 0.4 (2.5) 2.7 (4.2) 0.4 (4.6) 

* 156 dB re 1 μPa rms SPL threshold was used for this scenario since 153 dB re 1 μPa rms SPL threshold was beyond 50 km 

modeled range.

6.5.2.1.9. Sea State

A smooth sea surface is a near-perfect reflector of sound waves incident from below. However, ocean 

waves at the sea surface, due to local winds or from distant weather disturbances, can scatter sound in a 

non-uniform way. The degree of scattering depends on the amplitude of the surface roughness (wave 

height and wave crest separation), the wavelength of the sound energy, and the angle at which the sound 

energy is incident onto the surface. In very rough seas, breaking waves can entrap air bubbles, blurring

the actual position of the water-air interface. In general, scattering effects are small when the dimension 

of the surface roughness is small relative to the wavelength of the sound. Surface wave height is 

(typically) a function of wind speed, so higher frequency sounds are generally affected at lower wind 

speeds than lower frequency sounds. Sea-surface roughness generally has negligible effect on the 

propagation of sounds with frequencies < 50 Hz, where acoustic wavelengths are greater than 30 m. 

There can be a moderate effect on frequencies between 50 and 200 Hz, and a more significant effect on 

frequencies > 200 Hz in higher sea states. The additional coherent reflection losses at the air-sea interface 

due to the roughness of the boundary usually range from 0 to 2 dB per interaction and greatly depend on 

the grazing angle of the incoming wave (Long et al. 1989). 

Scattered sound energy is not lost and does not reduce the total amount of acoustic energy in the water. 

Scattering, however, has the effect of randomizing the phase of reflected sounds, thereby blurring the 
D-100 Acoustic Propagation and Marine Mammal Exposure Modeling

coherent interaction of reflected energy with sound that does not reflect. This results in a reduction of the 

strength of interference maxima and minima in the water column. The overall effect is to even out the 

otherwise more-variable spatial variations of sound levels in the water. In very rough conditions, when air 

is entrapped by breaking waves at the surface, high frequency sounds can be attenuated through 

absorption and high frequency levels can be reduced. 

Surface roughness depends on weather conditions, duration of increased winds, proximity to land, and on 

distant sea state patterns. For the acoustic propagation modeling here, we assumed perfectly calm 

conditions and a flat air-sea interface. This scenario leads to near perfect acoustic reflections. Although 

such conditions are rarely observed exactly, it is an often realistic approximation. It should be noted, 

however, that propagation in sound speed profiles that cause surface sound channels can be quite strongly 

affected, as sound can be scattered out of the duct. In those cases, sound levels in the channel can be 

substantially reduced. In the absence of a surface sound channel, or when sea state is low or moderate, the 

effects will generally be small.

6.5.2.1.10. Summary of Acoustic Uncertainty

Uncertainties in the results of acoustic propagation modeling were estimated by examining the variation 

in model outputs when model inputs were offset by realistic errors. The environmental properties were 

selected so that the median, or expected, value could be compared to a maximum-propagation outcome, 

which was generated by selecting extreme values for several input parameters. These comparisons 

represent the maximum errors in the predicted sound fields that result from incorrect specification of the 

parameters tested. Most of the comparisons were made at selected locations in the top 20 m of the water 

column, where marine mammals spend a substantial amount of time. 

For uncertainty in the sound speed profile, a difference of > 10 dB between the median and maximumpropagation scenarios was observed in the Shelf zone in both seasons (Table 30). The maximumpropagation scenario for the December–March period exhibited a strong surface duct (30 m/s difference 

between speed at the surface and maximum speed) that trapped the acoustic energy and propagated it with 

lower transmission loss. A surface duct was present in the median sound speed profile for the same 

period, but the maximum difference in sound speed was only 5 m/s. The difference in the sound fields for 

the April–November season was primarily due to a difference in the negative gradient below the surface 

duct where the maximum-propagation scenario sound speed profile was significantly less downward 

refracting. Surface ducts in the other zones were weaker, and variations in their sound speed profiles lead 

to less pronounced changes in sound propagation. The difference between the maximum-propagation and 

median scenarios in the Slope and Deep zones was < 4.0 dB. 

The greatest uncertainty due to geoacoustic parameters of the sea bottom is 4 dB, in the Deep zone 

(Table 34). The effect of the geoacoustic uncertainty increased when the sound speed profile was 

downwardly refracting. In the case of a surface channel (Slope zone, winter season), the average 

difference between the median and maximum-propagation was only 0.5 dB, i.e., in this case the 

geoacoustic parameters had virtually no effect on the sound levels at the top of the water column. Because 

the interaction of sound waves with the ocean bottom is most important in downward refracting 

environments, the uncertainty in the sound speed profile and geoacoustic parameters are negatively 

correlated.

Unlike the geoacoustic parameters, bathymetry is better documented and, unlike the sound speed profile, 

it does not change with time. For seismic surveys with moving sources, however, it is not practical to 

model the acoustic field for every possible source position. The common practice is to model acoustic 

propagation in a limited number of source positions and to use these derived fields as representative of the 

source operating in similar bathymetric regions. With this approach, there is uncertainty in the acoustic 

fields due to the presence or absence of local bathymetric features. Local features of the sea bottom 

generally affect specific azimuths and/or ranges while differences in the water depth affect regions of the 
Gulf of Mexico G&G Activities Programmatic EIS D-101

sound field. The analysis of uncertainty due to bathymetry showed that uncertainty varies with range from 

the source and there is a dependence on the water depth—the greater the water depth, the greater the 

range at which the highest uncertainty occurs. Comparison of the two cases in the Shelf zone revealed an 

uncertainty of about 4.5 dB within 500 m from the source (Table 35). In the Deep zone, the highest 

uncertainty occurred 5–10 km from the source. On average, the received levels differed by about 1.6 dB 

between the source operating in 2500 m and 2000 m depths. 

The weather-driven sea state also adds to the uncertainty in the acoustic field by changing the roughness 

at the air-sea interface. Scattering diminishes the extremes in the sound field, especially at higher 

frequencies. Sea-surface roughness negligibly affects the propagation of acoustic waves with frequencies 

< 50 Hz and moderately affects frequencies between 50 and 200 Hz, and can significantly affect higher 

frequency sounds. It is expected to have more effect when surface sound duct propagation is present. The 

acoustic propagation modeling assumed a flat air-sea interface, and because the airgun array was a lowfrequency source minimally affected by sea state, little uncertainty was expected due to sea state changes.

Uncertainties in the acoustic field discussed here represent a multi-dimensional envelope that can be 

wrapped around the main modeling results. This envelope is meant to enclose the modeled acoustic field 

and the real world acoustic field. The uncertainties in the different dimensions of this envelope (sound 

speed profile, geoacoustics, bathymetry, and sea state) cannot be summed to yield a “total” uncertainty as 

this would be a meaningless quantity. The overall uncertainty is measured for the volume of the multidimensional uncertainty envelope, but this is a difficult concept to use in operational planning. The best 

way to visualize the overall uncertainty is in terms of the different dimensions of the uncertainty 

envelope, as discussed above.

6.5.2.2. Animal Modeling Uncertainty

The exact location, behavioral, and motivational state of animals during an operation are not known and, 

as such, are the main sources of uncertainty in this modeling project. Those uncertainties are best 

addressed with animal movement simulations and Monte Carlo sampling which combines simulated 

animal movement from the Marine Mammal Movement and Behavior Model (3MB, Houser 2006) with 

the modeled sound fields of geotechnical and geophysical operation. Each simulated animal (animat) acts 

as a receiver and samples the sound field in a way real animals are expected to experience the sound field. 

With multiple animats sampling the sound field (Monte Carlo sampling), the distribution of received 

levels for the operation can be estimated as a probability of exposure. Exposure estimates can then be 

calculated from the exposure probability. 

6.5.2.2.1. Animal Movement Parameters Uncertainty

The movement parameters for 3MB are based on a two level process—a) preselected behavioral states 

and their temporal variation provide a framework for animat movements that b) follow a preselected 

stochastic processes for movement within the selected behavior states. The user-chosen parameters and 

preselected movement processes determine how simulated members of each species (animats) sample the 

sound fields. Uncertainty about the underlying motivation for any animal’s location choice means there is 

uncertainty in the parameters chosen for the model, and consequently uncertainty in the sampled received 

levels. Because there are many variables and a large range of possible parameter values, and oftentimes 

there are few data to support the model parameter values chosen, the uncertainty level can be high. It is 

impractical to conduct a parametric sensitivity analysis (as was done for Acoustic Modeling Uncertainty),

but the results from the six Test Case species (Section 6.3 and see Table 14 for species) can be compared. 

Because each species has distinct parameters that govern their movements, we were able to qualitatively 

compare how the different behavioral parameters might affect exposure estimates.
D-102 Acoustic Propagation and Marine Mammal Exposure Modeling

6.5.2.2.2. Summary of Animal Movement Parameter Uncertainty

Animal movement is simulated using an animal movement model, such as the 3MB (Houser 2006), and 

combined with the modeled sound fields of an operation. The 3MB incorporated many parameters to 

produce realistic animal movement. Each parameter could affect the estimated exposure levels 

independently or in association with each other. The results of the different modeled species are 

compared, giving a semi-quantitative indication of how different animal movement types affect exposure. 

The primary differences in the modeled exposure estimates among species are due to differences in 

animal acoustic sensitivity (Tables 14–15):

• Beaked whales have lower behavioral response thresholds than other species

• High-frequency dwarf sperm whales have lower injury thresholds than other species

• There is a larger range for potential injury due to accumulated energy for low-frequency species 

relative to the other species because of the weighting functions used; the low-frequency weighting 

function admits more acoustic energy from the low-frequency airgun source to propagate. 

When the same filtering and thresholds were applied, comparisons between animals resulted in similar 

exposure estimates. The exposure estimates for potential injury and exposure estimates for potential 

behavioral disruption for common bottlenose dolphins, short-finned pilot whales, and, to some extent 

sperm whales, were similar. For sperm whales, however, there was a marked difference in modeled 

exposure estimates between Survey sites A and B. This was due to a behavioral depth restriction for this 

species—sperm whales usually occur in water deeper than 1000 m. Because much of the survey area at 

Survey site A was shallower than 1000 m, few animats were near the source and the exposure levels were 

low through much of the modeling. Sperm whales also showed greater potential of behavioral response to 

noise exposure than other species with the same auditory thresholds. Sperm whales are deep divers; in 

this downward refracting environment they appear to be consistently exposed relative to the shallow 

divers such as Cuvier’s beaked whales, also a deep diving species, but with lower behavioral thresholds. 

Related to animal location and movement, but not currently captured by our animal movement modeling, 

are behavioral aspects that could increase uncertainty. Factors that affect the motivation of animals to 

remain at a certain location or to leave that location include the presence of prey and predators, which 

influence density. Another potential uncertainty is the socio-ecological need of animals to aggregate in 

groups. The sections below detail the effects of animal density and social group size on exposure 

estimates. 

6.5.2.2.3. Animal Density Estimates Uncertainty

The Monte Carlo simulations are run using a fixed animat density. Real-world animal density estimates 

are used to adjust the modeled (animat) exposure estimates to get real-world exposure estimates. Realworld density estimates are, very likely, the second largest source of uncertainty in the modeling project. 

Density estimates come from visual surveys (aerial and shipboard) and acoustic surveys. They are 

expensive, time consuming, and typically only examine small portions of populations for short times and 

often miss longer term and seasonal distribution patterns The best available data currently are from the 

U.S. Navy OPAREA Density Estimate (NODE) for the Gulf of Mexico (Department of the Navy 2007). 

For one region, the density estimates include minimum, maximum, mean, and standard deviation per area, 

e.g., km2

, assuming animals are normally, if not uniformly, distributed across the region. We often 

incorporated the uncertainty into the density estimates by reporting the impacts for the minimum, 

maximum, and mean density estimates, which bracket the range of expected impacts. We also used a 

resampling technique (bootstrap resampling) to estimate exposures with sample sizes scaled for the realworld density estimate.
Gulf of Mexico G&G Activities Programmatic EIS D-103

6.5.2.2.4. Animal Density Estimates Uncertainty Results

Estimates for the number of animats exposed to levels exceeding injury and behavioral response 

thresholds were determined in the 3-D WAZ survey of the Test Case (Section 6.3.2, Tables 14–15). Realworld exposure estimates were also determined and presented in the Test Case report (Tables 16–17). The 

real-world exposure estimates were obtained using the real-world density estimates (Table 36), which 

were used to adjust the modeled exposure estimates (Tables 14–15) to get the real-world exposure 

estimates (Tables 16–17). 

Table 36. Real-world density estimates for summer at Survey sites A and B. 

Modeled marine 

mammal species

Survey site A Survey site B

Min Max Mean σ Min Max Mean σ 

Bryde’s whales 0 0.000105 0.000081 0.000044 0 0.000105 0.000097 0.000029

Cuvier’s beaked 

whales 0.000003 0.004121 0.000676 0.000918 0 0.004121 0.000809 0.00092

Common 

bottlenose dolphins 0 0.2905 0.02181 0.027384 0 0.09859 0.003227 0.007823

Short-finned pilot 

whales 0 0.006277 0.004845 0.002657 0 0.006277 0.005785 0.001704

Sperm whales 0.000036 0.008154 0.002761 0.001859 0.000365 0.005395 0.002311 0.001496

Dwarf sperm 

whales 0 0.004605 0.000673 0.000912 0.000002 0.01558 0.001589 0.002174

min=minimum; max=maximum; σ=standard deviation

Bootstrap resampling

Bootstrap resampling is a random re-sampling (with replacement) technique used to quantify distribution 

accuracy for a sample estimate (e.g., Whitlock and Schluter 2009). Bootstrap resampling was used in this 

project to quantify the distribution accuracy of exposure probabilities and real-world exposure estimates 

(the number of animals above threshold) obtained from the Monte Carlo simulations of the six Test Case

species. The exposure probabilities were the received-level frequency of occurrence, which were

expressed as histograms (Figure 83A). The exposure probability histograms were randomly resampled, 

with replacement, and the number of animats exposed to levels above threshold was found (as the sample 

estimate). This process was repeated many times to get an expected distribution of animats with 

exposures above threshold. One sample drawn from the exposure probability is one bootstrap sample, one 

group of samples drawn from the exposure probability to represent a sample population is a bootstrap 

replicate. 

For example, there were 16,000 Bryde’s whale animats in the simulation, to maintain the same density 

throughout the resampling process 16,000 bootstrap samples could be taken as one bootstrap replicate, 

and 10,000 bootstrap replicates (of 16,000 samples each) obtained and the sample estimate calculated for 

each replicate. The sample estimate distribution is the distribution of animats exposed to levels above 

threshold for the bootstrap replicates (Figure 83B). Without resampling, there were 534 simulated 

Bryde’s whales at Survey site A with received levels above SEL 187 dB re 1 μPa2

·s (Table 14). 

Resampling obtained the range of animats above threshold and their probability of occurrence. In 

Figure 83B, the mean number of animats above threshold for the bootstrap replicates was also ~ 534, with 

a 5% likelihood of getting 495 or less animats and a 95% likelihood of 573 or less animats. There was 

90% chance that the number of animats above threshold was between 496 and 573. 
D-104 Acoustic Propagation and Marine Mammal Exposure Modeling

Without bootstrap resampling, the number of animats exposed to levels above threshold (Tables 14 and 

15) was adjusted by the real-world density (Table 36) to calculate the number of animals expected to be 

exposed to levels exceeding threshold (Tables 16 and 17). For Bryde’s whales at Survey site A, adjusting 

the 534 animats above threshold by the mean density estimate of 0.000081 resulted in 0.02 animals with 

above threshold exposures. When the minimum and maximum density estimates were used, the number 

of animals above threshold was < 0.01 and 0.03, respectively. With bootstrap resampling, changing the 

number of bootstrap samples in the bootstrap replicate is equivalent to changing the modeling density. To 

incorporate the uncertainty in the density estimates (standard deviation), the number of bootstrap samples 

in the bootstrap replicate was scaled by the ratio of the real-world density (± standard deviation) to the 

modeled density. The resulting distribution of real-world Bryde’s whales exposed to sound levels above 

threshold after resampling had a mean value of 0.0195, with a 98% likelihood of no animals above 

threshold, a 99.8% likelihood of 1 animal or less above threshold, and a maximum of 2 animals above 

threshold (Figure 83C). Note that the mean values with or without bootstrap resampling were about the 

same at 0.02 animals receiving levels above threshold and the range was also comparable, but the 

resampling procedure provided a more complete description of the sample estimate distribution. Similar

to the Bryde’s whales, the number of dwarf sperm whale animats exposed to levels above SEL injury 

threshold without resampling was 1053 at Survey site A and the real-world exposure estimate was 0.35 

animals. After bootstrap resampling was applied to the modeled animat exposure probability distribution 

and after the sample size for each bootstrap replicate was adjusted to reflect real-world animal density, the 

distribution of animals exposed to levels above threshold had a mean of 0.4019 with 71% of samples with 

no animals exposures above threshold. The number of animals receiving levels above threshold increased 

to 2 when 97.6% of replicates were considered while up to 7 animals could be exposed to levels above 

threshold when 99.5% of replicates were considered (Figure 83D). The remaining species (Cuvier’s 

beaked whales, common bottlenose dolphins, short-finned pilot whales, and sperm whales) either had 1 or 

no animats receiving levels above SEL injury threshold, so the sample distribution was essentially zero 

mean with zero variance (not shown). 

The same approach was used to obtain a distribution for potential behavioral responses. Figure 83E and F, 

show the real world behavioral disruption exposure estimate distributions for Bryde’s whales and dwarf 

sperm whales. For Bryde’s whales, the mean value matched the adjusted exposure estimate of 0.59 

animals (Table 16) and distribution includes 60% of bootstrap samples with zero animals exposed to 

levels above threshold, 95% of samples with 2 or fewer animals, and a maximum of 5 animals. For dwarf 

sperm whales, the mean number of animals with a potential behavioral response was 3.5 (close to the 

exposure estimate without resampling of 3.03 in Table 16); 30% of bootstrap samples showed no animals 

with a behavioral response, 50% showed 3 or fewer animals, 95% showed 10 or fewer, and the maximum 

was 20 animals exhibiting a behavioral response. For the remaining Test Case species, Figure 84 shows 

the resampled behavioral disruption exposure estimates and resampled exposure estimates adjusted for 

real-world densities. All means matched the (unadjusted) modeled exposure estimates (Table 14) within 

~ 2%. The means of the bootstrap resampled exposure estimates with bootstrap sample size were also 

close to the adjusted exposure estimate values (Table 16) for short-finned pilot whales and sperm whales, 

but were high for common bottlenose dolphins (120 versus 67) and Cuvier’s beaked whales (27 versus 23 

animals). Common bottlenose dolphins and Cuvier’s beaked whales had larger standard deviation of the 

density estimate than the mean density estimate. The ranges of exposure estimates with resampling for the 

species also matched the adjusted exposure estimates (maximum density in Table 16) reasonably well.
Gulf of Mexico G&G Activities Programmatic EIS D-105

Figure 83. Bootstrap resampling and SEL injury and behavioral response exposure estimation for Bryde’s 

whales and dwarf sperm whales. A) Exposure probability for Bryde’s whales from modeling 

expressed as a histogram, B) Estimated number of Bryde’s whale animats (modeled 

exposures) above SEL 187 dB re 1 μPa2·s using bootstrap resampling (10,000 bootstrap 

replicates, where each bootstrap replicate consisted of an equal number of bootstrap samples 

as the number of animats in simulation), and C) Estimated number Bryde’s whales (realworld exposures) above 187 dB SEL (re 1 μPa2·s) using bootstrap resampling with sample 

size adjusted for real-world mean ± standard deviation density estimate (10,000 bootstrap 

replicates, where the number of bootstrap samples in the replicate was scaled for the realworld density; in this case, the number of animats in simulation × 0.0000405 ± 0.000022). 

D) Estimated number of dwarf sperm whales (real-world exposures) above SEL 161 dB re 

1 μPa2·s using bootstrap resampling with bootstrap sample size adjusted for real-world mean 

± standard deviation density estimate (10,000 bootstrap replicates). E) and F) Behavioral 
D-106 Acoustic Propagation and Marine Mammal Exposure Modeling

disruption exposure estimate distribution for Bryde’s and dwarf sperm whales, respectively 

(10,000 bootstrap replicates with number of bootstrap samples adjusted for real-world 

density). Blue line shows cumulative probability in each plot. 

Figure 84. Bootstrap resampled behavioral disruption exposure estimate distribution for modeled results 

and adjusted for real-world density estimate mean ± standard deviation at Survey site A, A) 

model results and B) real-world exposure estimates for common bottlenose dolphins; C) 
Gulf of Mexico G&G Activities Programmatic EIS D-107

model results and D) real-world exposure estimates for Cuvier’s beaked whales; E) model 

results and F) real-world exposure estimates for short-finned pilot whales; and G) model 

results and H) real-world exposure estimates for sperm whales. 10,000 bootstrap replicates

were obtained with the number of bootstrap samples scaled for real-world density. Blue line 

shows the cumulative probability in each plot. 

6.5.2.2.5. Summary of Animal Density Estimate Uncertainty

The 3MB was run using animat densities (animats/km2

) that are typically much higher than in the realworld densities. Higher modeling densities were used so the sound field of an operation could be 

thoroughly sampled and provide a good estimate of exposure probability. 

To determine the expected number of real-world animals affected by an operation, the model results had 

to be adjusted by the real-world animal density estimates. There is uncertainty in the real-world density 

estimates, which can be quantified and presented as minimums, maximums, means, and standard 

deviations. As a way of bounding the range of potential impacts, the expected number of animals exposed 

to levels exceeding threshold can be determined for the minimum, maximum, and mean real-world 

density estimates. This method is most often used when presenting exposure estimates, i.e., the expected 

number of Level A or Level B exposures (see results in Section 6.3.2).

Another method that can be used to incorporate the uncertainty of real-world density estimates into 

exposure estimates is to use a resampling technique and include the mean and standard deviation of the 

real-world density estimate during the resampling process. We used a bootstrapping method (see 

Section 6.5.2.2.3) to resample the exposure probability distribution; the length of the bootstrap sample 

was adjusted by the mean and standard deviation of the real-world density estimate. The result of this 

bootstrap resampling was an exposure estimate distribution based on the number of potential real-world 

animals affected. Unlike the bracketing method, incorporating real-world density estimate standard 

deviation into the resampling process quantifies the probability of exposures as a range of potential 

exposures reflecting the variance of the density estimates. The mean value of the distribution essentially 

remains the same as the number of exposures calculated using the mean density estimate when bounding 

is used, but additional information is available in the shape of the distribution. The shape of the 

distribution could help evaluate the risk an operation poses. Knowing the likelihood that no animals will 

be exposed to levels exceeding threshold during an operation, or the number of animals exposed to levels 

exceeding threshold in 95% of the cases, gives a fuller picture of the risk due to the operation. 

To illustrate how this information helps us better understand risk, consider the Bryde’s whales for the 3-D 

WAZ survey at Survey site A, for which the real-world mean number of animals above the injury 

threshold (Level A exposure) was 0.0195. There is a 98% likelihood that none of these animals would 

exceed threshold during the operation, a 99.8% likelihood that one or no animal exceeds threshold, and no 

more than two animals above threshold (Figure 83C). For dwarf sperm whales, the real-world mean 

number of animals above the injury threshold was 0.4019 with a 71% likelihood that no animals would be 

above threshold, a 97.6% likelihood that two or fewer animals would be above threshold, and a 99.5% 

likelihood that seven or fewer animals would exceed threshold (Figure 83D).When incorporating the 

variability of the density estimates into the exposure estimate, we assumed that the uncertainty ascribed to 

the density estimates (i.e., minimum, maximum, mean, and standard deviation) reflects the real-world 

uncertainty in the density estimate for each of the modeled locations. In other words, we did not consider 

potential errors in the density estimates that were not captured by their own uncertainty estimates. 

6.5.2.2.6. Impact of Social Group Size on Exposure Estimates

Many animals form temporary or permanent social groups. When animals move in groups, the likelihood 

of their exposure within the sample region decreases, but the effect when exposure occurs increases 
D-108 Acoustic Propagation and Marine Mammal Exposure Modeling

proportionally with group size. Group size can affect how impacts should be interpreted, but this has not 

yet been quantified.

6.5.2.2.7. Impact of Social Group Size on Exposure Estimates: Methods

Bootstrap resampling was used to determine the distribution of exposure estimates assuming animats 

were in groups of animals, instead of a single animal. Group sizes might be large and disperse, but to 

more simply illustrate the effects of group sizes on exposure estimates, all members of a potential group 

were assumed to have the same received levels. 

Table 37. Published (social) group size statistics for Test Case species. The comments column describes how we 

used the source information to determine the mean group sizes suitable for post-process modeling. 

Mean SE Range Reference and area Comments

Common bottlenose dolphins

21 2 1–154

Maze-Foley and 

Mullin (2006)

Gulf of Mexico

NOAA separates Gulf animals into three ecotypes: inshore animals 

inhabiting bays and estuaries, coastal types mainly found on the 

shelf, and offshore types found on the shelf and upper slope 

(Waring et al. 2013). 

The three ecotypes support varying group sizes. Mean group sizes 

reported by Maze-Foley and Mullin (2006) likely include all three 

ecotypes. Toth et al. (2012) reported mean group size for coastal 

and offshore ecotypes in the Atlantic. Maximum value reported by 

Shane et al. (1986) represents offshore types off South Africa. 

Variations in observed group size are mainly due to whether the 

group was a feeding aggregate or if the group was traveling, etc. 

Deeper water groups are generally larger sizes. 

42 31–53 Toth et al. (2012)

Atlantic

1000 

(max.) 

Shane et al. (1986)

South Africa

Cuvier’s beaked whales

2 < 1 1–4 

Maze-Foley and 

Mullin (2006)

Gulf of Mexico

The similar group sizes encountered around the Hawaiian Islands 

and in the Gulf would indicate these are typical group sizes for the 

species.

McSweeney et al. 

(2007)

Hawaii 3 2 1–5 

Sperm whales

12 3–24 Christal et al. (1998)

Galapagos

Results from Maze-Foley and Mullin (2006) and Richter et al. 

(2008) were generated from some of the same survey data, but 

Richter et al. included newer survey data and used different 

detection probability method. Congruence of group sizes reported 

by Christal et al. (1998) in the Pacific and by Richter et al. (2008) in 

the Gulf indicates typical group size is ~ 11–15 animals. 

The higher mean in the Gulf data includes surveys performed in a 

year with unusual oceanographic conditions. These Gulf groups 

primarily consist of females, calves, and sub-adult males. Adult 

males temporarily joined groups. Stable female groups are based on 

long-term associations between individuals (Christal et al. 1998). 

3 < 1 1–11

Maze-Foley and 

Mullin (2006)

Gulf of Mexico

11 or 

15 3 Richter et al. (2008)

Gulf of Mexico

20

Whitehead and 

Arnbom (1987)

Pacific
Gulf of Mexico G&G Activities Programmatic EIS D-109

Mean SE Range Reference and area Comments

Dwarf sperm whales

2 1–10 Baird (2005)

Hawaii

Groups around the Hawaiian Islands and in the Gulf are similar in 

size, which indicates these group sizes are likely typical for the 

species.

2 < 1 1–8 

Maze-Foley and 

Mullin (2006)

Gulf of Mexico

Short-finned pilot whales

31 14–52

Kasuya and Marsh 

(1984)

Pacific 

The different methods of assessment are the likely reason reported 

group sizes vary considerably. Kasuya and Marsh (1984) captured 

animals during whaling operations. (Heimlich-Boran 1993) used 

long-term photo-identification of social groups. Mullin and Fulling 

(2004) and Maze-Foley and Mullin (2006) used ship surveys. 12–16 2–33

Heimlich-Boran 

(1993)

Canary Islands

34

Mullin and Fulling 

(2004)

Gulf of Mexico

25 4 3–85

Maze-Foley and 

Mullin (2006)

Gulf of Mexico

Bryde’s whales

1 1–15 Tershy (1992) 

Gulf of California 

More than 90% of the time Tershy (1992) encountered whales, they 

were alone. Given the similarity of the reported means in these 

references, we assumed a typical group size of two animals. 

2 Barlow (2006)

Hawaii

2 <1 1–5 

Maze-Foley and 

Mullin (2006)

Gulf of Mexico

SE = standard error

6.5.2.2.8. Impact of Social Group Size on Exposure Estimates: Results

For the species whose group size mean or median is similar across different regions and for which the 

measured variance or range was relatively small—such as Cuvier’s beaked whales, dwarf sperm whales, 

and Bryde’s whales—the reported mean or median and estimated standard deviation were used during the 

bootstrap resampling processing. For species with a much larger group size range, and for which 

normality of the size distribution could not be tested, the highest reported mean was used and a standard 

deviation was estimated from the range of reported group sizes. The social group sizes used to evaluate 

the effects of group size on the distribution of exposure estimates are shown in Table 38. 
D-110 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 38. Social group size (number of individuals ± standard deviation) used to evaluate effects on exposure 

estimates.

Species Group size

Bryde’s whales 2 ± 1

Cuvier’s beaked whales 3 ± 1.5

Common bottlenose dolphins 42 ± 6

Short-finned pilot whales 34 ± 10

Sperm whales 15 ± 3

Dwarf sperm whales 2 ± 1

During bootstrap resampling, each animat was considered to be a group of animals with the speciesspecific group size listed in Table 38. In the Bryde’s whales simulation at Survey site A, there were 

534 animats exposed to SEL above 192 dB re 1 μPa2

·s and 727.3 animats predicted to incur a behavioral 

response (Table 14). Figure 84A and B show that after bootstrap resampling was applied to the modeled 

animat exposure probability distribution and social group size was included, the sample estimate 

distribution of animats above threshold had a mean of 535 and 732, respectively for SEL injury and 

behavior (nearly the same as predicted in Table 14), but ~ 50% of the bootstrap samples had no animats 

above exposure threshold. In addition, the potential number of animats above threshold was much greater 

than the mean value; 95% of bootstrap samples had 1752 and 2326 (or less) animats above threshold with 

maximum estimates of 3134 and 3646 animats above threshold for injury and behavior, respectively. The 

results were very similar for dwarf sperm whales, where the mean exposure estimates after resampling are 

1058 and 442 (Figure 85C and D) versus 1053 and 451 (Table 14) for injury and behavior. 

The social group size used for both Bryde’s whales and dwarf sperm whales was 2 ± 1 animals. The 

effects of group size on the distribution of behavioral disruption exposure estimates for species with 

larger groups was even more pronounced. Nearly 98% of bootstrap samples indicate no animals with a 

behavioral response for common bottlenose dolphins (Figure 86A), 97% for short-finned pilot whales 

(Figure 86C), and 95% for sperm whales (Figure 86D), and in each case the number of potential animals 

impacted was much greater than the mean value.
Gulf of Mexico G&G Activities Programmatic EIS D-111

Figure 85. SEL Injury and behavioral disruption exposure estimate distributions for Bryde’s whales and 

dwarf sperm whales at Survey site A. A) SEL injury SEL exposure estimate distribution for 

Bryde’s whales. B) Behavioral response exposure estimate distribution for Bryde’s whales. 

C) SEL injury exposure estimate distribution for dwarf sperm whales. D) Behavioral 

disruption exposure estimate for dwarf sperm whales. All exposure estimate distribution were 

determined with 10,000 bootstrap samples, each bootstrap sample size was equal to the total 

number of animats in the simulation, and each animat was treated as a social group of size 

2 ± 1 animals (Table 38). Blue line shows the cumulative probability in each plot. 
D-112 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 86. Behavioral disruption exposure estimate distributions with social group size at Survey site A 

for A) Common bottlenose dolphins, B) Cuvier’s beaked whales, C) Short-finned pilot 

whales, D) Sperm whales. All exposure estimate distributions were determined with 10,000 

bootstrap samples, each bootstrap sample size was equal to the total number of grouped 

animats in the simulation based on the group size listed in Table 38. Blue line shows the 

cumulative probability in each plot.

6.5.2.2.9. Summary of Impact of Social Group Size on Exposure Estimates

Most animals have some ecologically driven grouping behaviors. Many cetaceans aggregate due to patchy 

food distribution (e.g., Jaquet and Gendron 2002, Burkhardt and Lanfredi 2012). Stable groups and a 

distinct social organization are key elements of the population structures of many, if not all odontocete 

species (Connor et al. 1998, Toth et al. 2012). While feeding aggregations create temporal fluctuations in 

group sizes, social group sizes may remain stable for a number of years (e.g., sperm whales, Christal et al. 

1998, Christal and Whitehead 2001) and possibly for their whole lives (e.g., pilot whales, Amos et al. 

1993, and possibly some beaked whales Kasuya et al. 1997). Interactions between social groups are 

characterized by temporary associations or avoidance, perhaps to reduce inter-group competition for food, 

a behavior that spatially influences animal distributions in populations. 

Group formation can affect exposure estimates in that grouping reduces the probability of exposure 

occurrence, but at the same time increases the number of impacted animals when exposures occur. 

Incorporating social groups into the animal movement modeling is difficult because temporary random 

associations and dissociations, such as group formation and dissolution, which could be related to patchy 

food availability, might form. Even long-term groupings might alter their makeup, move, or sample the 
Gulf of Mexico G&G Activities Programmatic EIS D-113

space differently than individuals. Social groups, by their very name, fulfil social functions, such as 

sharing care of young. Within social groups, individuals move in a more synchronized fashion than those 

in random feeding groups or groups of cooperative hunters that move in an even more coordinated 

fashion than other social groups. Allomothering, or babysitting, is an example of a group behavior seen in 

a number of cetaceans that directly affects group diving and swimming (Whitehead 1996, Hill and 

Campbell 2014). Allomothering creates groups of varying numbers of diving animals A number of 

animals remain at the surface or within the top 10 m of the water column at all times. Any acoustics effect 

that increases exposure in surface waters (e.g., surface ducting) will either increase the risk of animals 

staying at the surface and/or cause groups of animals to leave an area earlier than under quiet conditions, 

thus potentially affecting the amount of food required for optimal survival. Furthermore, higher exposure 

in surface waters will selectively affect younger animals because they do not dive to depth.

The effects of social grouping on exposure estimates can be shown by assuming that animats within the 

simulation are groups of animals instead of individuals. (As a note–groups can be simulated and the 

received level of individuals within the group can be tracked, but for simplicity in evaluating the effects 

of grouping, each animat was assumed to represent a group in which all individuals had the same 

exposure history.) During resampling, each animat was considered to be a population with a mean and 

standard deviation. Because each animat represents a group of animals, the effective modeling density 

was increased by the mean value of the group size, so the probability of exposure must be reduced by the 

same amount to account for the reduced likelihood of exposure. When group size was incorporated during 

the resampling process, the mean value of the exposure estimate distribution does not change relative to 

animats being considered as individuals, but the shape of the distribution can change markedly. For 

example, in the Bryde’s whale simulation at Survey site A there were 534 animats above the SEL injury 

threshold and 727.3 animats predicted to incur a behavioral response (Table 14). After bootstrap 

resampling was applied with group size included, the exposure estimate distribution of animats above 

threshold had means of 535 and 732, respectively for SEL injury and behavior. There was, however, a 

50% likelihood that no animats above threshold or predicted to have behavioral responses, and the 

potential number of animats above threshold was much greater than the mean value. The same group size 

(2 ± 1) was used for Bryde’s whales and dwarf sperm whales and thus the results were similar for the two 

species. Species with larger group sizes showed more pronounced exposure estimate distributions. 

Common bottlenose dolphins exhibited a 98% likelihood that no animals would have a behavioral 

response, short-finned pilot whales a 97% likelihood, and sperm whales a 95% likelihood. In each case, 

the number of potential animals affected was much greater than the mean value (Figure 86). 

6.5.2.3. Exposure Estimate Uncertainty

Both the uncertainty in acoustic modeling and uncertainty in the animal modeling contributed to the 

overall uncertainty in the exposure estimates. These uncertainties could be combined during the bootstrap 

resampling process to estimate exposure distributions that included the uncertainties from the various 

sources.

6.5.2.3.1. Exposure Estimate Uncertainty: Results

Acoustic uncertainty can be incorporated in the bootstrap resampling process by adding the uncertainty to 

the animats’ received levels. For potential injury, the primary acoustic uncertainly was the source level 

variance. Airguns are designed to have low inter-shot variability and predicted source levels within 3 dB 

(Section 6.5.2.1.1). A conservative estimate of ±3 dB standard deviation was used to investigate the 

effects of source level variance on SEL injury exposure estimates. We did not investigate effects of peak 

SPL variance because these were calculated based on range to the source, which was only ~ 18 m for 

most species. The effects of small changes in a small volume would be difficult to determine. Figure 87A 

shows that the mean number of animats above SEL threshold increases relative to the expected value (938 
D-114 Acoustic Propagation and Marine Mammal Exposure Modeling

vs. 534 for Bryde’s whales, and 1134 vs. 1053 for dwarf sperm whales). The exposure estimate 

distributions, however, did not change much; for both species, the range from 5% to 95% was about 100 

animats with or without acoustic variance. For potential behavioral disruption, propagation uncertainty 

also contributes to the uncertainty in the acoustic modeling predictions. Figure 87B shows the behavioral 

disruption exposure estimation distributions for Bryde’s whales and dwarf sperm whales when 6 dB of 

acoustic uncertainty (standard deviation) was included in the received levels during bootstrap resampling. 

6 dB was chosen as a test to include the ~ 4 dB uncertainty in propagation plus 3 dB in source variance. 

For behavior, the mean behavioral disruption exposure estimates (727 versus 727 for Bryde’s whales and 

459 versus 451 for dwarf sperm whales) and the distribution ranges (put ranges here) stay approximately 

the same when ± 6dB of acoustic variability was included. 

During resampling, acoustic uncertainty (3 dB for injury, 6 dB for behavior), can be combined with realworld density (mean ± standard deviation), and social group size (mean ± standard deviation). Figure 88

shows the potential real-world number of animals above the SEL injury threshold for Bryde’s whales 

(SEL > 192 dB re 1 μPa2

·s) and dwarf sperm whales (SEL > 161 dB re 1 μPa2·s). In the exposure 

estimate distributions, about 70% of the bootstrap replicates predict no animals above threshold (73% for 

Bryde’s and 64% for dwarf sperm whales). When 95% of the Bryde’s whales replicates were considered 

5 animals or less are above threshold and a maximum of 20 animals exceed the threshold in 100% of 

replicates. The corresponding values for dwarf sperm whales were 95% of the replicates have 49 animals 

or less above threshold with a maximum of 146 animals exposed to levels exceeding the threshold. For 

behavior, Bryde’s whales had 76% of replicates with no behavioral response; when increased to 95% 3 or 

less animals were impacted, and a maximum of 15 animals were above behavioral response threshold for

all of the replicates. Dwarf sperm whales had 65% of replicates with no behavioral response and up to 19 

or less animals in 95% of replicates, up to a maximum of 78 animals for all replicates. For Cuvier’s 

beaked whales, a species with lower behavioral thresholds, 75% of replicates showed no behavioral 

response of animals, while 3585 or less animals could potentially be affected when 95% of replicates 

were taken into account. Because of larger group sizes, common bottlenose dolphins, short-finned pilot, 

and sperm whales all showed no predicted behavioral responses in well over 90% of the replicates, but the 

potential number of animals impacted was much higher than the mean. 
Gulf of Mexico G&G Activities Programmatic EIS D-115

Figure 87. Bootstrap resampling with acoustic uncertainty for SEL injury potential behavioral response 

for Bryde’s whales and dwarf sperm whales at Survey site A. A) Bryde’s whales and B) 

Dwarf sperm whales potential SEL injury. The exposure estimate distributions are the 

number of animats above SEL 187 (Bryde’s whales) and 161 (dwarf sperm whales) dB re 

1 μPa2

·s with 10,000 bootstrap replicates where the number of bootstrap samples was equal 

to the number of animats in the simulation and the animat received level includes a standard 

deviation of 3 dB. C) Bryde’s whales and D) Dwarf sperm whales potential behavioral 

response. The exposure estimate distributions are the number of animats above the rms SPL 

step function with 10,000 bootstrap replicates where the number of bootstrap samples was

equal to the number of animats in the simulation and the animat received level includes a 

standard deviation of 6 dB. Blue line shows the cumulative probability in each plot. 
D-116 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 88. Bootstrap resampling for SEL injury for A) Bryde’s and B) Dwarf sperm whales at Survey 

site A with 3 dB of acoustic uncertainty, bootstrap sample size adjusted for real-world mean 

density ± standard deviation, and social group size of 2 ± 1 for both species. The exposure 

estimate distributions are the number of animals with the potential to receive an injurious 

exposure; 10,000 bootstrap replicates were obtained, and the blue line shows the cumulative 

probability in each plot. 
Gulf of Mexico G&G Activities Programmatic EIS D-117

Figure 89. Potential behavioral response exposure estimates of species at Survey site A from bootstrap 

resampling with acoustic uncertainty (± 6 dB), real-world density (mean ± standard deviation; 

Table 36), and social group size (mean ± standard deviation). A) Bryde’s whales, B) Dwarf 

sperm whales, C) Common bottlenose dolphins, D) Cuvier’s beaked whales, E) Short-finned 

pilot whales, F) Sperm whales. The exposure estimate distributions are the potential number 

of animals predicted to have a behavioral response. 10,000 bootstrap replicates were obtained 

and the blue line shows the cumulative probability in each plot. 
D-118 Acoustic Propagation and Marine Mammal Exposure Modeling

6.5.2.3.2. Summary of Exposure Estimate Uncertainty 

Traditionally, only a limited indication of uncertainty is included when presenting exposure estimates. 

The exposure estimate is usually the number of animals expected to exceed a threshold. Presenting a 

single value as the exposure estimate does not allow for a quantitative description of the variance in the 

modeling process. By presenting the exposure estimate as a distribution, a measure of uncertainty can be 

included in the exposure estimate. The exposure estimate distribution gives the probability of certain 

events occurring, such as the probability that an operation would not result in any animals above a defined 

threshold. 

Various sources of model uncertainty can be included in the resampling process to provide an exposure 

estimate distribution with uncertainty. In general, the uncertainty associated with the animals (density and 

group size) does not change the mean exposure estimate, but can profoundly affect the exposure estimate 

distribution. This phenomenon is especially pronounced when group size is included during the 

resampling process because the likelihood of exposure decreases by approximately the mean group size, 

concurrent with increasing consequences of the exposure (by approximately the mean group size). 

Uncertainty in the acoustic modeling can change the mean value of the exposure estimate because 

sampling near the tails of the exposure distribution is asymmetric, meaning more animats are typically

slightly below threshold than slightly above it, so uncertainty in the received level results in relatively 

more animats exposed to levels exceeding threshold. 

6.5.3. Test Scenario 3: Mitigation Effectiveness

Mitigation procedures to reduce adverse effects of sound exposures to marine mammals are often 

implemented during seismic surveys. The most common form of mitigation for injurious effects involves 

turning off the sound source (e.g., seismic array) when a protected animal is visually, or in some cases 

acoustically, detected within a pre-defined exclusion zone. Survey work resumes at a specified time 

interval after detection, allowing the animal to leave the exclusion zone. The effectiveness at reducing 

marine mammal exposure to potentially injurious sound levels with this commonly used approach is 

unknown. Mitigation effectiveness varies with the ability to detect an animal in the exclusion zone. Some 

species spend little time at the surface, so they are difficult to see. Others emerge frequently and visibly 

spout, so are easily seen. Detectability may decrease as the sea state increases as it is more difficult to 

visually-detect an animal in rough seas than in calm water. Detectability, and consequently mitigation 

efficacy, depends on the species, potentially individual animal characteristics, survey configuration, and 

environmental conditions. 

This Test Scenario uses a modeling approach to quantify the potential reduction in the numbers of 

exposures at or above Level A thresholds for selected species by comparing acoustic exposure estimates 

with and without mitigation (array shutdown). Specifically, a 3-D wide azimuth seismic survey was 

simulated for six representative species at two sites within the Gulf of Mexico (Figure 10). For each 

species, a range of detection probabilities was considered.

6.5.3.1. Mitigation Effectiveness Methods

Level A exposure estimates associated with the 5-day wide-azimuth survey simulation described in the 

Test Case simulations (Figure 20) were calculated with and without a mitigation procedure. Exposure 

estimates were computed relative to SEL, peak SPL, and rms SPL (180 dB re 1 μPa) exposure criteria 

(Section 5.4). Airgun shutdown was modeled by zeroing all animat received levels when an animat was 

detected within an exclusion zone. The animat detection was registered when the horizontal range of an 

animat from the source was less than an exclusion zone radius of 500 m, its depth was < 50 m, and a 
Gulf of Mexico G&G Activities Programmatic EIS D-119

random draw indicated detection. The 500 m exclusion zone was chosen based on the BOEM JOINT 

Notice to Lessees No. 2012-G02 (Lydersen and Kovacs 1999). 

To determine the effectiveness of mitigation, a measure of animal detection probability is needed. In 

cetacean surveys, the generally adopted methodology to determine animal abundance and density 

involves an assessment of the detection probability g(0), which is estimated from visual or acoustic 

surveys for animals. Detection probability is the likelihood of detecting an animal within an area along a 

trackline (usually a circle around a survey vessel) and is biased by availability (detection is limited due to 

environmental factors) and perception (observers miss detecting an available animal). The estimated 

probability is based on the statistical correlation between two independent, but temporally correlated 

observations assumed to be those of the same animals (Buckland 2001). The metric include parts the 

vertical water column cylinder below the surface that can be surveyed simultaneously, so it depends on 

survey methodology. The accuracy of g(0) is higher for simultaneously conducted visual and acoustic 

surveys than for two visual surveys due to lower availability bias, but accuracy varies with species and 

environmental conditions (e.g., sea state, wind, rain and resulting ambient noise level) and ultimately 

availability of animals for detection is limited for both survey methods (Barlow 2013). The g(0) during 

visual surveys has been estimated for a number of species in a variety of conditions (see Section 6.5.3.1.2

below). The positions of animats in the simulation are known and reported in short time steps. The g(0), 

however, is the probability of detecting an animal along the trackline as the survey passes through an 

area, rather than for an individual time step. For this Test Scenario, g(0) is used as estimate of the 

detection probability for animats near the surface and close to the vessel. 

Simulations typically use a much higher animat density than the real-world animal density. For these 

reasons, we reduced the number of animats (see Section 6.5.3.1.1 below) to that of the real-world density 

for each species and checked for detection only once for each animat that entered the exclusion zone. To 

assign detections, a random value from a uniform distribution between 0 and 1 was generated for each 

animat in the exclusion zone and whose depth was < 50 m. The value for each animat was thresholded 

against g(0). If the random value was less than g(0), the detection was registered, the time of the closest 

point of approach (CPA) was found, and the received levels for all animats were zeroed for 30 min before 

and after the CPA. Normally the true shutdown would occur for 1 h following the detection, but for our 

purposes the specific timing is not important as animats are independent, and the centered window 

conveniently allowed the detected animat to avoid being exposed. 

For the purposes of the simulation, it was assumed that array shutdown was the only mitigation procedure 

performed, and it was assumed that portions of the survey line missed during shutdown were re-surveyed 

(i.e., shutdowns result in an increase in the overall survey duration in order to keep the distance surveyed 

the same as the unmitigated case). Shutdown was assumed to occur only for the source (array) around 

which the animat was detected. Other sources present in the simulation continued operating. Because it is 

impossible to accurately predict g(0) for an operation, a likely range was used for each species 

(Section 6.5.3.1.2). 

6.5.3.1.1. Bootstrap Resampling

We used bootstrap resampling (see Bootstrap Resampling in Section 6.5.2.2.4 ) to quantify the number of 

animals exposed to levels above Level A thresholds obtained from the Monte Carlo simulations of the six 

Test Case species, with and without mitigation. Again, the exposure probabilities are the received-level 

frequency of occurrence expressed as histograms. 10,000 bootstrap replicates were obtained, where the 

number of bootstrap samples in each replicate were adjusted by the ratio of the real-world density to the 

model density, and the number of animats exposed to levels above threshold (SEL or peak SPL) was 

found for each bootstrap replicate. Without mitigation, the resampling provides a baseline distribution of 

expected exposures, which is compared to the exposure estimate distribution with mitigation. The mean 

difference and the relative change between the two estimate distributions were calculated to quantify the 
D-120 Acoustic Propagation and Marine Mammal Exposure Modeling

effect of mitigation on exposure estimates. Mitigation was incorporated into the bootstrap process during 

each replicate by testing if an animat was within the exclusion zone and detected. If a detection occurred 

the received levels for each animat in the replicate were zeroed for 30 min before and 30 min after the 

detection to simulate a shutdown.

6.5.3.1.2. Detection Probability

In surveys designed to determine animal presence or abundance, independent observations along different 

tracklines or temporally shifted observations along the same trackline (such as circling back in aerial 

surveys) provide an indication of all or a known fraction of detectable animals and can be used to estimate 

detection probability, typically g(0) (Buckland et al. 2001). 

Detection probability varies with species, environmental conditions, and group size. Large whales that 

spend considerable time with portions of their body above the water surface and exhale a visible spout 

when resurfacing are more easily spotted than cryptic species that spend much of their time submerged 

and only break the surface for short breaths. Likewise, there are more opportunities to spot large groups 

than solitary animals. Detection probability decreases for all species as sea state increases, but the greatest 

decrease is for the difficult-to-detect species (MacIntyre et al. In Press). For example, Moore and 

Barlow (2013) noted a decrease in g(0) for Cuvier’s beaked whales from 0.23 at Beaufort sea 

state 0 (calm) to 0.024 at sea state 5 (wave height 2–3 m). Table 39 shows g(0) reported for the six test 

species for a range of sea states (Beaufort sea states 0–5). These data are from surveys at locations around 

the world, as indicated in the table footnotes, but are good proxies for trackline detection probabilities of 

the Gulf of Mexico species.

Model simulations were run for detection probabilities of 0.05 to 0.45 simulate an assumed range of 

probabilities for animats in the upper 50 meters of the water column independent of the species. 

Simulations were run in increments of 0.05, to estimate the likely range of detection probabilities for 

beaked whales and dwarf sperm whales (for which Barlow (2006) noted low detection probabilities). 

Simulations for all other species were modeled with g(0) ranging from 0.5 to 0.9, in increments of 0.1. 

Table 39. Estimates of trackline detection probability, g(0), coefficients of variation (CV) for g(0), and mean group 

size. The CV for each estimate of g(0) is shown in parentheses.

Species

g(0) Estimates for group size ranges* 

1–20 > 20

Common bottlenose dolphinsa 0.76 (0.14) 1.00 (n/a)

Short-finned pilot whalesa 0.76 (0.14) 1.00 (n/a)

Sperm whalesb 0.87 (0.09) 0.87 (0.09)

Dwarf sperm whalesc 0.35 (0.29)

Cuvier’s beaked whalesc 0.23 (0.35)

Bryde’s whalesa 0.90 (0.07)

* In Barlow (2006) Table 2, pg. 451. a The g(0) estimates from Barlow (1995), based on his categories of small delphinids, large delphinids, and other large whales. 

Large and small delphinids are pooled based on the similarity in their g(0) values (0.74 and 0.77, respectively, for groups of less 

than 20).

b The g(0) estimates from Baird et al. (2006a) for sperm whales with 30-min dives. c The g(0) estimates from Barlow (1999) based on his categories of Kogia spp., Mesoplodon spp., and Ziphius cavirostris. 
Gulf of Mexico G&G Activities Programmatic EIS D-121

6.5.3.2. Mitigation Effectiveness Results

The average number of cetaceans exposed to sounds above Level A exposure criteria was computed for 

Survey sites A (shallower water) and B (deeper water) for the six sample species. Exposure estimates 

were computed both with and without mitigation, producing an estimate of the mitigation effectiveness 

for each site and species modeled (Tables 40–44). For all species except the high-frequency dwarf sperm 

whales, no or a vanishing small number of SEL exposures were registered with and without mitigation. In 

the case of Bryde’s whales, some animats were exposed to sound exceeding the SEL or SPL thresholds, 

however, their low real-world density meant only rarely was an animat exposed to levels above threshold 

chosen during bootstrap resampling. 

Sample plots of the probability distribution of peak SPL and rms SPL exposure estimates, without and 

with mitigation, are shown in Figures 90–94 for five of the six species modeled at Survey site A (results 

for Bryde’s whales were trivial, as noted above). Each figure shows the example for the mid-range 

detection probability. 

Table 40. Cuvier’s beaked whales: Modeled Level A exposure estimates and mitigation efficiency for peak SPL and 

rms SPL. 

Metric Detection 

probability

Average number of cetaceans above exposure criteria

Survey site A Survey site B 

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

peak SPL

0.05 0.032 0.032 0.001 (2%) 0.040 0.040 0.001 (2%)

0.15 0.032 0.030 0.002 (5%) 0.038 0.036 0.002 (6%)

0.25 0.030 0.028 0.003 (9%) 0.039 0.036 0.003 (8%)

0.35 0.034 0.028 0.005 (16%) 0.036 0.031 0.005 (14%)

0.45 0.031 0.024 0.007 (21%) 0.038 0.032 0.006 (16%)

rms SPL

0.05 0.123 0.120 0.003 (2%) 0.136 0.135 0.001 (1%)

0.15 0.122 0.115 0.007 (6%) 0.138 0.130 0.008 (6%)

0.25 0.126 0.113 0.013 (11%) 0.137 0.124 0.013 (10%)

0.35 0.121 0.104 0.016 (14%) 0.144 0.129 0.015 (11%)

0.45 0.122 0.099 0.023 (19%) 0.141 0.117 0.024 (17%)
D-122 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 41. Common bottlenose dolphins: Modeled Level A exposure estimates and mitigation efficiency for peak 

SPL and rms SPL. 

Metric Detection 

probability

Average number of cetaceans above exposure criteria

Survey site A Survey site B 

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

peak SPL

0.5 1.364 0.778 0.586 (43%) 0.189 0.096 0.092 (49%)

0.6 1.353 0.741 0.612 (45%) 0.203 0.089 0.114 (56%)

0.7 1.329 0.654 0.675 (51%) 0.187 0.062 0.125 (67%)

0.8 1.335 0.553 0.781 (59%) 0.188 0.051 0.137 (73%)

0.9 1.354 0.398 0.956 (71%) 0.190 0.028 0.162 (85%)

rms SPL

0.5 4.510 2.561 1.949 (43%) 0.627 0.335 0.292 (47%)

0.6 4.505 2.386 2.119 (47%) 0.630 0.281 0.349 (55%)

0.7 4.528 2.128 2.400 (53%) 0.624 0.214 0.411 (66%)

0.8 4.527 1.703 2.825 (62%) 0.623 0.153 0.470 (75%)

0.9 4.520 1.104 3.416 (76%) 0.631 0.087 0.544 (86%)

Table 42. Short-finned pilot whales: Modeled Level A exposure estimates and mitigation efficiency for peak SPL

and rms SPL. 

Metric Detection 

probability

Average number of cetaceans above exposure criteria

Survey site A Survey site B 

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

peak SPL

0.5 0.275 0.155 0.120 (44%) 0.334 0.186 0.148 (44%)

0.6 0.284 0.143 0.141 (50%) 0.339 0.157 0.181 (54%)

0.7 0.274 0.108 0.166 (61%) 0.341 0.135 0.205 (60%)

0.8 0.281 0.085 0.196 (70%) 0.338 0.105 0.234 (69%)

0.9 0.277 0.057 0.220 (80%) 0.339 0.064 0.275 (81%)

rms SPL

0.5 0.989 0.535 0.454 (46%) 1.225 0.663 0.562 (46%)

0.6 0.993 0.454 0.539 (54%) 1.212 0.563 0.649 (54%)

0.7 0.986 0.369 0.617 (63%) 1.216 0.456 0.760 (63%)

0.8 0.991 0.271 0.720 (73%) 1.228 0.340 0.888 (72%)

0.9 0.980 0.162 0.818 (83%) 1.224 0.206 1.017 (83%)
Gulf of Mexico G&G Activities Programmatic EIS D-123

Table 43. Sperm whales: Modeled Level A exposure estimates and mitigation efficiency for peak SPL and rms SPL. 

Metric Detection 

probability

Average number of cetaceans above exposure criteria

Survey site A Survey site B 

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

peak SPL

0.5 0.086 0.072 0.013 (15%) 0.121 0.102 0.019 (16%)

0.6 0.086 0.073 0.013 (15%) 0.119 0.098 0.021 (18%)

0.7 0.084 0.064 0.020 (24%) 0.121 0.095 0.026 (21%)

0.8 0.087 0.068 0.019 (22%) 0.124 0.095 0.029 (24%)

0.9 0.081 0.058 0.022 (28%) 0.117 0.084 0.033 (29%)

rms SPL

0.5 0.344 0.295 0.049 (14%) 0.395 0.337 0.058 (15%)

0.6 0.336 0.281 0.055 (16%) 0.399 0.332 0.067 (17%)

0.7 0.337 0.267 0.069 (21%) 0.399 0.322 0.077 (19%)

0.8 0.337 0.264 0.073 (22%) 0.399 0.315 0.084 (21%)

0.9 0.330 0.249 0.082 (25%) 0.388 0.294 0.094 (24%)

Table 44. Dwarf-sperm whales: Modeled Level A exposure estimates and mitigation efficiency for 5-day SEL, peak 

SPL, and rms SPL. 

Metric

Detection 

probabilit

y 

Average number of cetaceans above exposure criteria

Survey site A Survey site B 

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

Without 

mitigation

With 

mitigation

Mitigation 

effectiveness

5-day SEL

0.05 0.320 0.311 0.009 (3%) 0.635 0.620 0.015 (2%)

0.15 0.321 0.277 0.044 (14%) 0.632 0.557 0.076 (12%)

0.25 0.326 0.253 0.072 (22%) 0.632 0.493 0.139 (22%)

0.35 0.322 0.216 0.106 (33%) 0.630 0.424 0.206 (33%)

0.45 0.304 0.177 0.127 (42%) 0.639 0.372 0.267 (42%)

peak SPL

0.05 0.865 0.869 −0.004 (0%) 1.955 1.989 −0.034 (−2%)

0.15 0.871 0.859 0.012 (1%) 1.947 1.943 0.004 (0%)

0.25 0.880 0.847 0.033 (4%) 1.932 1.886 0.047 (2%)

0.35 0.865 0.814 0.051 (6%) 1.950 1.841 0.109 (6%)

0.45 0.861 0.780 0.081 (9%) 1.935 1.769 0.166 (9%)

rms SPL

0.05 0.055 0.054 0.001 (1%) 0.130 0.127 0.003 (2%)

0.15 0.055 0.047 0.008 (14% 0.127 0.114 0.014 (11%)

0.25 0.055 0.043 0.012 (22%) 0.129 0.101 0.029 (22%)

0.35 0.053 0.037 0.017 (31%) 0.130 0.089 0.040 (31%)

0.45 0.055 0.033 0.023 (41%) 0.134 0.078 0.056 (42%)
D-124 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 90. Cuvier’s beaked whales: Probability of exposure above injury thresholds at Survey site A 

without (left panels) and with mitigation (right panels) for peak SPL (top panels) and rms 

SPL (bottom panels). Detection probability is 0.25. The blue line is the cumulative 

distribution. 
Gulf of Mexico G&G Activities Programmatic EIS D-125

Figure 91. Common bottlenose dolphins: Probability of exposure at or above injury thresholds at Survey 

site A without (left panels) and with mitigation (right panels) for peak SPL (top panels) and 

rms SPL (bottom panels). Detection probability is 0.7. The blue line is the cumulative 

distribution. 
D-126 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 92. Short-finned pilot whales: Probability of exposure at or above injury thresholds at Survey 

site A without (left panels) and with mitigation (right panels) for peak SPL (top panels) and 

rms SPL (bottom panels). Detection probability is 0.7. The blue line is the cumulative 

distribution. 
Gulf of Mexico G&G Activities Programmatic EIS D-127

Figure 93. Sperm whales: Probability of exposure at or above injury thresholds at Survey site A without 

(left panels) and with mitigation (right panels) for peak SPL (top panels) and rms SPL 

(bottom panels). Detection probability is 0.7. The blue line is the cumulative distribution. 
D-128 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 94. Dwarf sperm whales: Probability of exposure at or above injury thresholds at Survey site A 

without (left panels) and with mitigation (right panels) for SEL (top panels), peak SPL 

(middle panels), and rms SPL (bottom panels). Detection probability is 0.25. The blue line is 

the cumulative distribution. 
Gulf of Mexico G&G Activities Programmatic EIS D-129

6.5.3.3. Summary of Mitigation Effectiveness

The inclusion of mitigation procedures in the simulations reduced the numbers of exposures based on 

peak SPL and rms SPL criteria for five out of six species and detection probabilities considered, even 

though an extension in the survey period due to line re-shoot was taken into account. The exception was 

Bryde’s whales, for which real-world densities were so low that no exposures were modeled even in the 

absence of mitigation. The numbers of exposures based on the SEL criteria were zero for most species 

(even without mitigation), except for dwarf sperm whales. For dwarf sperm whales, there was a reduction 

in SEL exposures with mitigation, but, as with the peak SPL criteria, the reduction amounted to fractions 

of an animal. Mitigation effectiveness, expressed as the reduction in the number of individual animals 

exposed, was generally related to animal densities; species with higher densities were more often exposed

and the reduction in the number of exposures from mitigation was greater. 

Mitigation effectiveness, as measured by the percentage reduction in the exposure estimates, is 

predominantly a function of animal detection probability during a seismic survey. The greater the 

detection probability, the greater the effectiveness of shutdown mitigation. The percentage reduction in 

exposures for species with relatively high detection probability (common bottlenose dolphins, shortfinned pilot whales, and sperm whales) was higher than the percentage reduction for species with 

relatively low detection probability (Cuvier’s beaked whales and dwarf sperm whales). Bryde’s whales

had no exposures with or without mitigation. In addition, the detection probability of beaked and dwarf 

sperm whales is potentially lower than reported from surveys due to uncertainty of detection availability. 

This also lead to a higher uncertainty in measuring mitigation effectiveness for these species using 

detection probability metrics. For deep diving species with unreliable vocal rates, a very conservative 

estimate of mitigation effectiveness should be used.

To summarize, the usefulness of mitigation depends on species characteristics and environmental 

conditions. Mitigation effectiveness, measured as percent reduction in exposures relative to no mitigation, 

tracks with detection probability and animal density. The absolute number of exposed animals reduced by 

mitigation is mainly dependent on how many animals were originally affected by the survey. The 

reduction due to mitigation for easily-detected, species with large populations, e.g., a large group of 

dolphins, may be high in terms of percentage decrease (perhaps ~ 70%) and absolute number of animals. 

For low-density species that are difficult to detect in rough seas (e.g., cryptic, deep-diving species like 

beaked whales), the efforts of mitigation may produce little mitigating effect.

6.5.4. Test Scenario 4: Effects of Aversion on Acoustic Exposure Estimates

Animals can display a range of behaviors in response to anthropogenic sounds, including increased 

respiration rates, increased or decreased vocalization rates, and changes in swimming speed (Nowacek et 

al. 2007). There can be substantial variation in individuals’ responses to acoustic exposures; there are 

many examples where individuals of the same species exposed to the same sound reacted differently 

(Nowacek et al. 2004). If sounds are perceived as a threat or an annoyance, animals might temporarily or 

permanently avoid the area near the source (Stansfield and Matheson 2003, Southall et al. 2007, Ellison et 

al. 2012). Animals moving to avoid sound is called aversion. 

Aversive responses to sounds are of particular interest because such behavior could decrease the number 

of injuries that result from acoustic exposure. If aversion occurs at a level less than that considered an 

exposure, a decrease in the corresponding exposure estimates can be assumed. The degree of aversion and 

level of onset for aversion, however, are poorly understood. 

This Test Scenario uses a modeling approach to quantify the potential reduction in injury exposure 

estimates. Aversion is simulated as a reduction in received levels and, because little is known about the 

received levels at which animals begin to avert, the sound levels and probabilities used to evaluate 

potential behavioral disruption are used to implement aversion. This report only addresses the effects of 
D-130 Acoustic Propagation and Marine Mammal Exposure Modeling

aversion on potential injury exposures; disturbance or behavioral exposures are not considered because 

the aversive thresholds used are the same as the current behavioral disruption exposure thresholds. 

Consequently, based on these thresholds, aversion itself represents a behavioral disruption exposure. It is 

important to note that, if aversion thresholds were lower than behavioral disruption exposure thresholds, 

then aversion could also reduce behavioral exposures. 

6.5.4.1. Effects of Aversion on Acoustic Exposure Estimates Methods

Injury exposure estimates associated with the 5-day WAZ simulation (Section 6.3.2) were determined 

with and without aversion. For each site and species, distributions of expected exposures were calculated 

using bootstrap resampling (Section 6.5.3.1.1) of the animats’ acoustic exposure histories generated in the 

course of the Test Case simulations. For computational efficiency, the number of animats per bootstrap 

replicate was scaled by the ratio of the real-word animal densities to the modeling density. To simulate 

aversion, a modified exposure history was generated as outlined in Section 6.5.4.2, and injury exposure 

estimates were computed relative to SEL, peak SPL, and rms SPL (180 dB re 1 μPa) exposure criteria 

(Sections 5.4.2 and 5.4.3). The difference in the mean value of the exposure estimate distributions with 

and without aversion indicates the effect of aversion on the injury exposure estimates. 

6.5.4.2. Exposure History with Aversion

Each animat sampled during the bootstrap process (Section 6.5.3.1.1) has an associated exposure history, 

i.e., a time series of received sound levels arising from relative motion of the source and animat. These 

exposure histories were computed assuming the animats’ behaviors were otherwise unaffected by their 

received sound levels. Each exposure history was then modified based on received-level dependent 

probabilities of averting: 

1. For each bootstrap sample, the occurrence of aversion was determined probabilistically based on the 

exposure level and the probability of aversion using the step function defined in Section 5.4.3 for SEL 

and peak SPL, and 50% probability at 160 dB rms SPL for 180 dB rms SPL. An iteration-specific 

aversion efficacy was also chosen randomly from a uniform distribution in the range of 2–10 dB.

2. Animats for which aversion occurred in Step 1 had their received levels adjusted as described in the 

following steps. The received levels were unchanged for animats that did not avert.

3. For an animat entering an averted state, the aversion level excesses (the levels above the threshold 

that prompted aversion) until the end of the aversion episode were calculated from the difference 

between the received level at the start of aversion and the threshold level at which aversion began up 

to a maximum of 5 dB. 

4. The adjusted received level during aversion was set to the greater of two quantities: 

• The received level minus the aversion efficacy (from Step 1), or

• The threshold level plus the aversion level excess at the start of aversion (from Step 3) 

Adjusted exposure histories were computed separately for each source, animat, and episode of aversion; 

each occurrence of aversive behavior was thus independent. 

Although the probability of aversion was defined in terms of the rms SPL, exposure histories were 

recorded in terms of the per-pulse SEL. A nominal conversion offset of +10 dB from SEL to rms SPL, 

corresponding to a pulse arrival duration of ~ 100 ms (Section 5.2.4), was used so the two metrics could 

be compared. Additionally, 5-day SELs, used to compute injury exposure estimates, were weighted using 

Type I M-weighting for low-frequency cetaceans (Bryde’s whales) and Type II M-weighting for mid- and 

high-frequency cetaceans, but behavioral effects were estimated using Type I M-weighting for all species 
Gulf of Mexico G&G Activities Programmatic EIS D-131

considered (Section 5.4.1). As such, the 5-day SEL exposure histories for mid- and high-frequency 

cetaceans were adjusted upward by an amount corresponding to the K1 value of the Type II M-weighting 

functions (i.e., 16.5 dB for mid-frequency cetaceans and 19.4 dB for high-frequency cetaceans; 

Section 5.4.1) before they were compared to the aversion threshold levels (see Section 5.4 for exposure 

criteria levels developed for this study).

6.5.4.3. Effects of Aversion on Acoustic Exposure Estimates: Results

The average number of cetaceans exposed to sounds above the potential injury threshold was computed 

for Survey sites A (shallower water) and B (deeper water) for the six sample species. Exposure estimates 

were computed with and without aversion, producing an estimate of the aversion effectiveness for each 

site and species modeled (Table 45). For all species except the high-frequency dwarf sperm whales, no or 

a vanishingly small number of SEL exposures were registered with and without aversion. In the case of 

Bryde’s whales, their very low real-world density led to a small number of bootstrap samples in each 

replicate and animats exposed to sound levels above SEL threshold were very rarely chosen during 

bootstrap resampling. Because the probability of exposure cannot truly be zero, and to keep our reporting 

convention consistent, the exposure estimates are listed as < 0.01 for these cases. 

Sample plots of the probability distribution of injury exposure estimates, with and without aversion, are 

shown in Figures 95–100. In each case, the cumulative probability is shown as a blue line and the mean 

value (i.e., the expected number of exposures) is labeled. When the step function was used to determine 

aversion, the median amount of time common bottlenose dolphin, dwarf sperm whale, short-finned pilot 

whale, and sperm whale animats spent in an averted state was approximately 7 min at Survey site A and 

2 min at Survey site B. The corresponding mean times were approximately 18 and 4 min, respectively. 

For beaked whales, the median was 45 min at Survey site A and 5 min at Survey site B and the 

corresponding means were 41 and 19 min. Too few Bryde’s whale animats exceeded threshold to obtain a 

reliable statistical measure. 
D-132 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 45. Modeled Level A exposures, with and without aversion.

Species Metric

Average number of cetaceans above exposure criteria

Survey site A Survey site B 

Without 

aversion

With 

aversion

Aversion 

effectiveness

Without 

aversion

With 

aversion

Aversion 

effectiveness

Bryde’s whales

5-day SEL < 0.01 < 0.01 N/A < 0.01 < 0.01 N/A

peak SPL < 0.01 < 0.01 N/A < 0.01 < 0.01 N/A

rms SPL 0.341 0.299 0.043 (12%) 0.390 0.336 0.054 (14%)

Cuvier’s beaked 

whales

5-day SEL < 0.01 < 0.01 N/A < 0.01 < 0.01 N/A

peak SPL 0.033 0.006 0.028 (83%) 0.038 0.004 0.034 (89%)

rms SPL 1.930 1.604 0.326 (17%) 2.662 2.237 0.425 (16%)

Common 

bottlenose 

dolphins

5-day SEL < 0.01 < 0.01 N/A < 0.01 < 0.01 N/A

peak SPL 1.357 0.219 1.139 (84%) 0.191 0.033 0.159 (83%)

rms SPL 68.701 57.940 0.761 (16%) 9.798 8.043 1.756 (18%)

Short-finned 

pilot whales

5-day SEL < 0.01 < 0.01 N/A < 0.01 < 0.01 N/A

peak SPL 0.279 0.040 0.239 (86%) 0.346 0.052 0.294 (85%)

rms SPL 13.287 11.410 1.877 (14%) 18.311 15.521 2.790 (15%)

Sperm whales

5-day SEL < 0.01 < 0.01 N/A < 0.01 < 0.01 N/A

peak SPL 0.082 0.013 0.069 (84%) 0.126 0.020 0.106 (84%)

rms SPL 4.744 3.819 0.925 (20%) 8.969 7.555 1.414 (16%)

Dwarf sperm 

whales

5-day SEL 0.318 0.191 0.127 (40%) 0.647 0.399 0.248 (38%)

peak SPL 0.859 0.774 0.086 (10%) 1.958 1.756 0.202 (10%)

rms SPL 1.756 1.421 0.335 (19%) 4.708 3.795 0.912 (19%)

Figure 95. Probability of exposure at or above rms SPL injury thresholds for Bryde’s whales at Survey 

site A, (left) without and (right) with aversion. The blue line is the cumulative distribution. 
Gulf of Mexico G&G Activities Programmatic EIS D-133

Figure 96. Probability of exposure at or above peak SPL (top panels) and rms SPL (bottom panels) injury

thresholds for Cuvier’s beaked whales at Survey site A, without (left panels) and with 

aversion (right panels). The blue line is the cumulative distribution. 
D-134 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 97. Probability of exposure at or above peak SPL (top panels) and rms SPL (bottom panels) injury

thresholds for common bottlenose dolphins at Survey site A, without (left panels) and with 

(right panels) aversion. The blue line is the cumulative distribution. 
Gulf of Mexico G&G Activities Programmatic EIS D-135

Figure 98. Probability of exposure at or above peak SPL (top panels) and rms SPL (bottom panels) injury 

thresholds for short-finned pilot whales at Survey site A, without (left panels) and with (right

panels) aversion. The blue line is the cumulative distribution.
D-136 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 99. Probability of exposure at or above peak SPL (top panels) and rms SPL (bottom panels) 

thresholds for sperm whales at Survey site A, without (left panels) and with (right panels) 

aversion. The blue line is the cumulative distribution.
Gulf of Mexico G&G Activities Programmatic EIS D-137

Figure 100. Probability of exposure at or above (top panels) SEL, (middle panels) peak SPL, rms SPL 

(bottom panels) injury thresholds for dwarf sperm whales at Survey site A, without (left 

panels) and with (right panels) aversion. The blue line in each plot is the cumulative 

distribution. 
D-138 Acoustic Propagation and Marine Mammal Exposure Modeling

6.5.4.4. Summary of Effects of Aversion on Acoustic Exposure Estimates

Responses to sound carry potential health costs to animals. Hiding or retreating from an ensonified area 

could decrease their foraging time and/or increase the energy they spend searching for food (Bateson 

2007). In most cases, animals likely expend less energy temporarily avoiding or averting noise by 

changing their travel or migratory routes, than they would if their foraging was interrupted. The 

circumstances under which aversion occurs depends on the context in which the animals receive sounds 

and on the animals’ motivation. The decision to deviate from a path or avoid an ensonified area is likely 

driven by energetic and reproductive requirements (Croll et al. 2001). For example, bowhead whales who 

avoided distant seismic airguns at received levels of rms SPL of 120–130 dB re 1 μPa during fall 

migration (Richardson et al. 1999) were more tolerant of airgun sounds while feeding in the summer. The 

feeding whales avoided airguns only when received levels reached 152–178 dB re 1 μPa, roughly 30–

50 dB higher than migrating avoidance levels (Richardson et al. 1995). 

Stone and Tasker (2006) reported that small odontocetes showed the strongest reaction to airgun sounds 

by moving away from or avoiding an ensonified area. Mysticetes and killer whales showed more 

localized avoidance, with fewer sightings when the source was active; long-finned pilot whales only

changed their orientation; and sperm whales showed no significant avoidance response (Stone and Tasker 

2006). Others (e.g., Rankin and Evans 1998) also noted sperm whales’ apparent lack of response to 

seismic operations. In controlled exposure experiments, eight tagged sperm whales over a series of 

120 min intervals during pre-exposure, ramp-up, and full-array airgun firing did not avoid airgun sounds 

by adjusting their position horizontally; only one individual adjusted its diving and foraging rate by 

resting longer at the surface and diving immediately following the final airgun pulse (Miller et al. 2009). 

In contrast, during the first 72 h of a 10-day seismic survey, fin whales moved away from the airgun 

array. This displacement persisted well beyond the 10-day duration of seismic airgun activity (Castellote 

et al. 2012). Though consistent with aversion to airgun sounds, another possibility is that the animals were 

following a food source that was not tracked during the observations. Gender-specific responses were also 

observed. Resting female humpback whales avoided seismic surveys by distancing themselves from the 

source by 7–12 km, whereas males were occasionally attracted to the sounds (McCauley et al. 2000a). 

To assess how aversion could reduce injury exposure estimates, a simple model was created that allowed 

for lower exposure levels for animats in the simulation, based probabilistically on their received level.

Any animat that averted was considered to have a behavioral response so only the effects of aversion on 

injury exposures were considered.

Aversion in the simulations reduced the numbers of exposures based on peak SPL criteria for most 

species. Aversion effectiveness, as measured by the percentage reduction in the exposure estimates, could 

be high: ~ 85% for common bottlenose dolphins, Cuvier’s beaked whales, short-finned pilot whales, and 

sperm whales, and ~ 40% for dwarf sperm whales. Bryde’s whales, whose real-world densities were so 

low that no exposures were modeled even in the absence of aversion, were the exception. The numbers of 

exposures based on SEL criteria were near zero for most species even without aversion. For dwarf sperm 

whales, there was a reduction in SEL exposures with aversion, but as with the peak SPL criteria, the 

reduction amounted to a fraction of an animal. There was a consistent reduction of 14–20% in exposures 

above rms SPL 180 dB re μPa based on aversion starting at rms SPL 160 dB re μPa for all species. The 

reduction in the number of individuals above rms SPL 180 dB re μPa ranged from a fraction of an animal 

to more than ten individuals. Aversion effectiveness, expressed as the reduction in the number of 

exposures, was generally related to animal densities: species with higher densities were more often 

exposed, and the reduction in the number of exposures from aversion was greater. This reduction in 

exposures was also influenced by the criteria used to estimate exposures and by the assumptions made 

with respect to aversion probability. For example, although the real-world densities of dwarf sperm 

whales (a high-frequency cetacean) are similar to those for Cuvier’s beaked whales (a mid-frequency 

cetacean), exposure estimates and the decrease in number of exposure estimates arising from aversion 

were different. The differences in aversion effectiveness reflect differences in injury threshold criteria and 
Gulf of Mexico G&G Activities Programmatic EIS D-139

aversion probability. The Cuvier’s beaked whales’ behavioral response thresholds are lower than other 

species, leading to potential aversion at lower received levels and greater reduction in injury exposures 

based on the SPL metric. Dwarf sperm whales had more absolute exposures and less reduction because of 

their lower behavioral response thresholds and larger ensonified area in which injury could occur. 

6.5.5. Test Scenarios 5 and 6: Stand-off Distance and Simultaneous Firing

Modern geophysical seismic surveys employ a variety of seismic sources, including airgun arrays. Recent 

survey practices have included survey geometries that with multiple airgun arrays, separated by tens of 

meters to several kilometers, in a single survey. New technologies for analyzing seismic data are less 

sensitive to interference of noise between multiple surveys, and this has allowed for different surveys to 

be performed closer together than previously. There is concern that the combined sound pressure levels of 

multiple sources operated close-by can lead to increased noise effects than would occur with a single 

source. This Test Scenario report addresses the issue of the aggregate noise produced by multiple airgun 

arrays and the potential for those signals to combine and lead to larger effects. 

Airgun arrays consist of multiple airguns that are fired almost simultaneously to increase the amplitude of 

the overall source pressure signal. The combined sound emission amplitude and directivity of an airgun

array is dependent on the number and sizes of individual airguns and their geometric positions within the 

array. Airgun arrays are typically operated repetitively as the arrays are towed over a survey grid pattern. 

The time intervals between airgun shots are optimized for water depth and the distance of important 

geological features below seafloor; there must be enough time between shots for the sound signals to 

propagate down to and reflect from the feature of interest, and then to propagate upward to be received on 

hydrophones. Reverberation of sound from previous shots must also be given time to dissipate. The 

receiving hydrophones can be towed behind or in-front of the airgun array, or deployed on the seabed. 

These can be displaced several kilometers horizontally away from the source, so horizontal propagation 

time is also considered in setting the interval between shots. 

Many 3-D surveys now use two or more airgun array sources to get different ‘views’ of geological 

features. A common approach for these surveys has been to tow two arrays spaced horizontally a few tens 

of meters away from each other, and to fire them alternately. This alternate firing of pairs of arrays is 

referred to as ‘flip-flop’ mode. More recently, wider offsets of the airgun arrays are achieved by towing 

the arrays from different vessels. Surveys of this type are referred to as wide azimuth, and they are be 

performed with multiple vessels spaced from hundreds or thousands of meters apart, with each vessel 

towing its own airgun array or arrays.

In these cases, a stand-off distance may be required for operational and data quality purposes. A minimum 

standoff distance may be desired, or required for permitting, to allow a corridor for animals to pass 

between adjacent work zones. Determining the underwater sound field of surveys involving multiple 

arrays with potential overlap is more complex than evaluating the impacts due to a single-array survey 

because relative locations and relative shot timing might have to be taken into account. The influence of 

stand-off distance and simultaneous firing on acoustic exposure estimates is explored here. 

6.5.5.1. Stand-off Distance

Multiple seismic surveys may be conducted nearby one another at the same time. The sound emissions of 

the multiple sources from these surveys, operating in close proximity, can lead to increased received 

sound levels for nearby marine mammals. A minimum separation distance between the surveys, referred 

to as a stand-off distance, may be mandated to keep the noise exposures lower. If the stand-off distance 

keeps the surveys sufficiently separated, the estimates of marine mammal exposures for either survey, i.e., 

the number of animals exposed to sound levels above exposure thresholds, is largely independent of the 

presence of the other survey. If the surveys move closer together, nearby marine mammals can experience 
D-140 Acoustic Propagation and Marine Mammal Exposure Modeling

sound exposure contributions from both surveys, potentially increasing their total exposures above effects 

thresholds and consequently causing additional exposures. In the case where a marine mammal 

approaches two surveys close enough to exceed the exposure threshold of both independently, it is only 

considered to have been exposed once (if the exposures occur within the reset period). In those cases, the 

number of exposures might actually be reduced by smaller stand-off distances. The issue of value of 

stand-off distance is therefore not straightforward. It is further complicated by the fact that the SPL and 

SEL sound metrics, all used for exposure assessments, vary differently in the presence of sound 

contributions from two or more surveys. 

SPL is a metric used for both injurious and behavioral exposure assessments. SPL of impulsive airgun 

sounds is calculated over relatively short time windows, almost always less than 1 s and commonly 

approximately 100 ms, during which the highest amplitude parts of the pulse-like sounds occur (see 

Figure 15a, which shows the pressure waveform of the 8000 in3 array from the Test Case). When two 

seismic surveys are operating nearby, marine mammal receivers can experience pulses from both surveys. 

However, unless those pulses happen to arrive near-simultaneously at the receiver, the SPLs do not sum 

and the SPL exposure will be that only of the louder survey (at the receiver position). Interpulse time 

intervals typically are 10 to 20 s, with 15 s being quite common. Using that as an example, with a SPL 

time window of 100 ms, only one in 75 pulses will have some degree of important overlap for a given 

receiver, and that will usually only be partial. This example neglects that signals in deep waters can have 

several discrete arrivals associated with multipaths (e.g., Figure 101, which shows pressure waveform 

shapes at several distances from the 8000 in3 array source at Survey site A, from the Test Case, in 500 m 

water depth), but typically just one of those paths dominates. In the maximum-propagation scenario of 

full overlap and signals from both arrays having the same SPLs, the SPL increase would be about 3 dB. 

Generally, one signal will have higher amplitude than the other and the potential increase will be less. For 

example, if the received SPL from one survey is 158 dB re 1 μPa, and the other is 155 dB re 1 μPa, the 

fully overlapped pulses would have a combined SPL of 159.8 dB re 1 μPa, an increase of less than 2 dB 

over the higher-amplitude pulse, assuming they have the same pulse duration. 

While the expected SPL increases from multiple surveys are relatively small, and occur infrequently, 

SPL-based exposures occur on a single instance of an exposure above the threshold. The behavior-based 

threshold may be exceeded several kilometers from either source, so there is a chance an animal mid-way 

between two surveys, and receiving similar SPL levels from both, could experience an increase by up to 

3 dB when exposed to overlapping sounds from both surveys. To avoid this effect entirely would require 

stand-off distances of twice the distance to the exposure threshold minus 3 dB. Under the assumption of 

20 log R (spherical spreading) transmission loss, the stand-off distance would have to be more than 3 

times the distance to the exposure threshold to ensure that summed levels always fall off to the exposure 

threshold mid-way between the two sources. This geometry, however, leads to the largest combined 

exposure zone because the exposure zones of the individual surveys meet at the mid-point. In fact, much 

smaller stand-off distances reduce the size of the combined exposure zone. 

The peak SPL metric is used to assess potential injury exposures close to a source. Peak SPLs occur over 

very short times, and the argument for rare overlaps of pulses, provided above for SPL, is even more 

pronounced for peak pressure. The likelihood of temporal overlaps of pressure peaks is very limited. 

Further, the peak pressure injury threshold exceedance zones are so small (typically a few hundred 

meters) that marine mammals would be extremely unlikely to experience an overlap that would lead to a 

peak pressure acoustic exposure that did not occur from a single survey source. 
Gulf of Mexico G&G Activities Programmatic EIS D-141

Figure 101. Waveforms predicted by FWRAM for the 8000 in3 array at Survey site A, for a 10 m receiver 

depth. Waveforms are shown as a function of horizontal range from the receiver. Positive 

pressures are filled in black. The key feature is that pressure signals for individual multipaths 

are short in duration, here generally 50–100 ms. 

SEL is a measure of accumulated sound energy. Unlike the previously described metrics of SPL and peak 

pressure, it does not depend on the structure (time and phase) of the received sound, and it increases 

throughout the reset period with each received pulse. For example, Figure 102 shows the unweighted SEL 

field for the start of a 3-D WAZ survey, assuming stationary receivers (as opposed to the moving animats 

used to compute exposure estimates). When surveys are close enough for animals to receive energy from 

two or more surveys, some animals that would have been below threshold in one survey could accumulate 

sufficient additional energy to exceed threshold in the aggregate of the surveys. In this case, an exposure 

would occur when no exposure would have been registered if the surveys did not overlap. For the current 

SEL criteria (Section 5.4.2), which apply only to potential injury, ranges for which injury may occur are 

on the order of a few hundred meters from the source. As such, overlap must occur over similarly short 

ranges to affect exposures. For example, even in high-density simulations (2 animats/km2

) of the 3-D 

WAZ surveys, no animats were exposed to levels exceeding the SEL threshold for mid-frequency species 

at Survey site B (deep) and only common bottlenose dolphin and Cuvier’s beaked whale animats were 

exposed to levels exceeding the threshold at Survey site A. For Bryde’s whales (low frequency) and 

dwarf sperm whales (high frequency), the number of acoustic exposures was much higher, but when realworld animal densities are considered, SEL exceedance is still rare and resulted from being near an 

individual source once rather than accumulating energy from multiple sources. Overall, exceeding the 

SEL threshold is a rare event and having four vessels close to each other (350 m between tracks) did not 

cause appreciable accumulation of energy at the ranges relevant for injury exposures, thus accumulation 

of energy from independent surveys is expected to be negligible. 
D-142 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 102. Sound exposure level for four 8000 in3 arrays at the start of a 3-D wide azimuth seismic 

survey at Survey site A, S01 modeling province. Arrays are offset by an across-track distance 

of 350 m and an along-track distance of 2.7 km. Tow speed is 2.3 m/s, and shot interval for 

each vessel is 86.4 s.

6.5.5.2. Simultaneous Firing

Traditional large-scale surveys involving multiple airgun arrays towed from multiple vessels alternate, or 

distribute, the shots fired among the arrays. Some modern surveys now fire multiple arrays 

simultaneously. This simultaneous firing warrants special consideration for its potential to affect 

estimated exposures. 
Gulf of Mexico G&G Activities Programmatic EIS D-143

Coincidence of pulse arrival is only of concern for metrics based on sound pressure (the energy-related 

metric, SEL, is simply summed and does not rely on signal timing). As discussed in Section 6.5.5.1, the 

sound pressure at a location with multiple impinging sources is a function of the arrival time, shape, and 

phase of each arriving pulse. The greatest pressure amplitude is when two identical pulses arrive at the 

same time and in the same phase. These pulses sum coherently, doubling the sound pressure or, 

equivalently, increasing the SPL by 6 dB. Because phase varies with time, location, and frequency as 

sound propagates away from a source, coherent summing occurs only with nearly-coincident 

synchronized sources such as those within a single array. For separate arrays the pressure signals combine 

incoherently, with a maximum SPL increase of 3 dB, as described previously. More precisely, the 

incoherent sum of the rms SPLs from two arriving pulses in regions of overlap may be estimated as 

follows: 

1

2

2

1

1 2

1

1 , )10/(log)10/(log log10 Tt

tT

LTLT

L p p

p <∆ 















∆+

× ×+ =

− −

 (20) 

where Lp1 and Lp2 are the rms SPLs of the two pulses (dB re 1 μPa), T1 and T2 are time windows for 

computation of rms SPL (s), log−1 is the antilog function, and Δt is the difference in arrival time of the 

two pulses. The sum of more than two pulses is computed similarly. Where pulses do not overlap, the 

received SPL is taken to be the maximum SPL of the two individual pulses. For example, Figure 103

shows the maximum-over-depth rms SPL sound fields for one 8000 in3 array and for two identical arrays 

fired simultaneously with an across-track separation of 350 m and an along-track separation of 2700 m (as 

in Figure 102 showing SEL). While there are some regions where the combined sound field is louder than 

the individual sound fields (e.g., the small extensions to the isopleths visible in the across-track direction 

in the bottom panel of Figure 103), the individual and combined sound fields are nearly identical. Similar 

results would be expected for simultaneous firing of three or four arrays. 
D-144 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 103. SPL for (top) one 8000 in3

 array and (bottom) two 8000 in3 arrays fired simultaneously with 

an across-track separation of 350 m and an along-track separation of 2700 m.
Gulf of Mexico G&G Activities Programmatic EIS D-145

6.5.5.3. Summary of Stand-off Distance and Simultaneous Firing

It was found that while SEL increases for overlapping surveys, injury due to accumulated energy is a rare 

event, and exceeding threshold resulted from a few high-level exposures near a source, not an 

accumulation of many lower-level exposures. The range to injury assessed by peak SPL is up to a few 

hundred meters and does not accumulate. Injury in typical seismic surveys, therefore, occurs mainly 

because of a close encounter with a single airgun array. There are practical limits to how close two 

acquisition lines can be without one survey source interfering with the other survey’s recordings. 

Depending on the survey type and the propagation environment of the area, the stand-off distance 

between fully concurrent surveys operating independently may be several tens of kilometers. If two 

surveys are conducted in closer proximity, then the operators will generally agree to “time-sharing” 

strategies whereby, for example, one survey acquires a line while the other completes a line turn with the 

source inactive, or similar ways of minimizing the amount of missed effort. Effects of overlapping 

surveys on injury exposure estimates are unlikely.

For potential behavioral disruption, overlapping surveys may affect exposure estimates, but the effect is 

either small or potentially negative (reducing the overall number of estimated exposures). Because 

coincident reception in which the sound level increases appreciably only occurs in small portions of the 

ensonified volume, overlapping survey sound fields do not generally result in higher maximum received 

sound pressure levels. And, because animals may only be exposed once, animals exposed in more than 

one survey are only counted once in the aggregate of the surveys. This does not preclude possible 

behavioral effects of animals spending more time above threshold, but such effects are not addressed by 

existing criteria.

From an energetic perspective, the relative firing pattern of different arrays does not matter. The same 

SEL will be registered when two arrays are alternated or fired simultaneously. For the pressure-based 

metrics, peak SPL and rms SPL, simultaneous firing can increase the received levels, but in only a small 

portion the ensonified volume. Because the maximum received levels are rarely increased, the exposure 

estimates based on SPL are rarely increased. The most likely place for meaningful summation to occur is 

very near the source, and in that case the firing pattern would be included in the simulation and therefore 

in the exposure estimates. 

In sum, neither stand-off distance nor simultaneous firing are of significant concern when estimating 

exposures using the current criteria. 
D-146 Acoustic Propagation and Marine Mammal Exposure Modeling

6.6. Cumulative and Chronic Effects Assessment Framework

6.6.1. Overview

A cumulative sound exposure calculation framework was developed to assist with assessing chronic 

seismic exploration noise received by marine mammals at a set of ten pre-defined receiver locations 

(Table 46) in the Gulf of Mexico. This framework is implemented as Excel spreadsheets with scripting to 

provide a flexible tool for evaluating potential effects of scenarios representing different levels of seismic 

exploration activity over wide areas of the Gulf of Mexico. The spreadsheets incorporate the results of 

acoustic modeling of the same 8000 in3 seismic array and single 90 in3 airgun that were considered in the 

broader environmental assessment. Source directivity is accounted for with an azimuthal resolution of 

22.5°. Model results are currently available for winter and summer seasons and at three possible receiver 

depths: 5 m, 30 m and 500 m. 

Table 46. Receiver site locations and water depths.

Site # Receiver Site Name Latitude Longitude Water Depth

1 Western Gulf 27.01606 -95.7405 842

2 Florid Escarpment 25.95807 -84.6956 693

3 Midwestern Gulf 27.43300 -92.1200 830

4 Sperm Whale site 24.34771 -83.7727 1053

5 Deep offshore 27.64026 -87.0285 3050

6 Mississippi Canyon 28.15455 -89.3971 1106

7 Bryde’s Whale site 28.74043 -85.7302 212

8 De Soto Canyon 29.14145 -87.1762 919

9 FGBNMS* 27.86713 -93.8259 88

10 Bottlenose Dolphin Site 29.40526 -93.3247 12

*Flower Garden Banks National Marine Sanctuary

Spreadsheets store the acoustic transmission loss results generated by the parabolic equation model 

(MONM) used in the broader assessment. The model was used to generate range and direction-dependent 

transmission loss along radials 150 km long that converge on the receiver sites. The radials are in 

azimuthal steps of 22.5° and the transmission loss results along each were modeled at the center 

frequencies of all consecutive 1/3-octave-bands from 10 Hz to 5 kHz. The modeling geometry was 

implemented using acoustic reciprocity, whereby the model was run with the source and receiver 

positions interchanged—an efficient approach when there are more potential source sites than receiver 

sites. 

The spreadsheets also contain several sets of frequency weighting coefficients that can be applied to the 

received levels. Currently the framework supports the Low-Frequency Cetacean (LF1), Mid-Frequency 

Cetacean (MF1), and High-Frequency Cetacean (HF1) filters as defined by Southall et al. (2007), and the 

equal-loudness weightings for Low-Frequency Cetaceans (LF2), Mid-Frequency Cetaceans (MF2), and 

High-Frequency Cetaceans (HF2) as defined by Finneran and Jenkins (2012). It is straightforward to add 

other weightings by including them in the weighting table spreadsheet. 
Gulf of Mexico G&G Activities Programmatic EIS D-147

6.6.2. Method of Use

The spreadsheet scripting initially displays a data entry screen with two panes to the user: one for entering 

receiver-based and general information, and the other for entering information related to multiple seismic 

surveys. 

The general information pane has four fields: 

• Select Frequency Filter: displays a drop-down list of filter types that include unweighted, LFC1, 

MFC1, HFC1, LFC2, MFC2, HFC2 as described above. 

• Select Site: displays a drop-down list of the ten receiver sites (Table 46).

• Receiver Depth: displays a list of the possible depths: 5 m, 30 m, and 500 m. If water depth is less 

than 30 m or 500 m then those options are listed as n/a. 

• Month: current choices are July or December.

The spreadsheet displays information based on the choices made, as shown in this example of the general 

information pane: 

 

The seismic survey entry pane is a multi-line data entry area in which the user can enter information 

associated with each of the surveys considered. These are the primary inputs for each seismic survey:

• Location: Entered in latitude and longitude in WGS-83 coordinates. The current version of the 

framework assumes the source is fixed at this location for the duration of the survey, although a 

single survey can be divided into multiple sub-parts at different locations.

• Array type and operating depth: Selected from a drop-down list. Currently the framework includes an 

8000 in3

 airgun array operating at 8 m depth and a 90 in3 single airgun operating at 4 m depth. 

• Duration: The total operating time in seconds. The total cumulative operating time does not include 

break times. It is used with shot interval to calculate the total number of seismic shots or pulses.

• Shot interval: The time in seconds between each seismic shot or pulse. That typically ranges from 10-

20 seconds, but can be shorter in shallow waters. This value is used with survey duration to calculate 

the number of pulses accounted for in the cumulative sound exposure level calculation.

• Azimuth: The direction, in degrees, relative to true North that the seismic array is towed. 90° is due 

east. The value is used to select the appropriate direction-dependent source levels.

Up to 50 separate seismic surveys can be entered in the survey entry pane. The spreadsheet automatically 

computes and displays several other fields in the greyed-out “control numbers” section: 

LFC1 N 28.155 East: 853873 Water

depth

Site 6 W 89.397 North: 3119577 1100 m Mississippi Canyon - Sperm whales, cryptic deep divers

5 m

July Season: S3

Select Frequency Filter:

Select site:

Receiver depth:

Month:

Description
D-148 Acoustic Propagation and Marine Mammal Exposure Modeling

The framework contains a separate sheet that displays a map of the first ten survey locations with the 

receiver locations. The map also shows the currently-selected receiver position, which is displayed using 

a different symbol than the other receiver positions. This map is help for reviewing survey location values 

relative to a chosen receiver. An example map is shown in Figure 104. 

Figure 104. Map automatically produced by the cumulative and chronic effects calculator, 

showing seismic survey positions and receiver locations. The seismic survey locations are 

shown as green dots. Receiver stations are shown as red stars, except for the selected receiver 

which is shown as a red diamond.

#

Active

Lat Lon

Duration 

(seconds)

Shot interval

(seconds) Type

Tow

azimuth

Number of

shots East North Range Azimuth

1 yes 29.000 -89.500 864000 30.00 8000 in3 at 8 m 90 28800 841013 3213039 94343 352.2

2 yes 28.000 -89.600 864000 10.00 90 in3 at 4 m 90 86400 834407 3101864 26318 227.7

3 yes 29.000 -91.000 864000 30.00 8000 in3 at 8 m 10 28800 694821 3209635 182778 109.5

4 yes 29.000 -91.500 864000 15.00 90 in3 at 4 m 350 57600 646109 3208913 226156 123.3

5 yes 27.000 -89.700 864000 10.00 90 in3 at 4 m 350 86400 827517 2990720 131524 21.6

6 yes 27.000 -89.800 864000 30.00 8000 in3 at 8 m 350 28800 817586 2990464 134115 25.7

Surveys Source: Control numbers:
Gulf of Mexico G&G Activities Programmatic EIS D-149

6.6.3. Calculator Output

The calculator computes cumulative frequency-weighted sound exposure level (SEL) at a selected 

receiver location and depth from all shots from all seismic surveys specified. The modeled radial lengths 

are 150 km, so surveys more distant than that from a receiver will not contribute to the calculated 

received SEL. The calculator computes the SEL contribution of each survey separately as follows:

5. Looks up the 1/3-octave band per-pulse SEL source levels based on the selected source type and 

depth, and the calculated direction to the receiver that depends on source and receiver locations and 

source tow direction. 

6. Extracts the appropriate 1/3-octave band transmission loss levels based on the selected source depth 

and receiver depth and closest modeled radial passing by the source position. 

7. Subtracts the transmission losses from the source levels in each frequency band to compute 

unweighted received per-pulse band levels.

8. Calculates the number of pulses in the survey based on the survey duration and pulse interval, and 

sums this number of received per-pulse SELs to calculate the unweighted band SEL for the entire 

survey.

9. Applies the 1/3-octave filter coefficients for the selected filter to the corresponding received band 

levels for the entire survey.

10. Sums the filtered 1/3-octave band received levels to compute a broadband filtered SEL for the survey 

as a single number.

The final cumulative frequency-weighted SEL at the receiver from all surveys is the sum of the results of 

individual surveys. The calculator displays the individual survey SELs and the total exposure. An 

example of this output is given in the screen capture below (note only the first 13 of 50 surveys is 

captured in the figure so the total exposure doesn’t match the sum of those displayed): 
D-150 Acoustic Propagation and Marine Mammal Exposure Modeling

6.6.4. Discussion

Few studies of cumulative and chronic effects have involved quantitative assessments of the type this 

framework provides. There are no generally accepted methods for interpreting cumulative SEL in terms 

of chronic effects, and there are no thresholds defined for this use. In the Gulf of Mexico, seismic surveys 

continue year-round and, at least in deeper locations, the sounds from distant surveys contribute to a 

relatively continuous background noise field that is above natural ambient. Superimposed on this 

background field are the contributions of closer-range seismic surveys that have shorter durations, 

typically of a few weeks, but those surveys lead to substantially higher sound levels. Initial tests with the 

framework have shown that seismic surveys close to receivers dominate the received cumulative SEL, 

which raises questions about how to interpret the results, such as: 

• Should chronic effects assessments neglect close-range surveys that produce higher received sound 

levels, but occur for limited periods, and if so, which surveys should be excluded? 

• What errors are introduced by assuming fixed seismic survey locations for surveys that in reality can 

have large spatial extents that lead to significant received sound level variations?

The cumulative and chronic effects calculator framework developed here is being used to investigate such 

questions with a goal of developing systematic methods to deal with the issues. The framework will then 

be applied to assess potential chronic effects from seismic survey noise in the Gulf of Mexico. 

Per-pulse Per-survey

1 81.6 126.2

2 103.7 153.1

3 100.8 145.3

4 63.7 111.3

5 75.5 124.9

6 100.2 144.8

7 99.6 147.2

8 100.8 148.4

9 100.8 150.1

10 100.8 148.4

11 100.8 148.4

12 100.8 148.4

13 100.8 148.4

Individual survey Exposures

Total exposure:

161.0 dB re 1 μPa·s2
Gulf of Mexico G&G Activities Programmatic EIS D-151

7. Phase II: Marine Mammal Exposure Estimates 

The goal of Phase II of this study was to estimate the yearly acoustic exposures received by marine 

mammals to geological and geophysical survey activities in the Gulf of Mexico for the coming decade. 

Phase I demonstrated and explored the basic methodological approach using agent-based animal 

movement in simulated sound fields as a Monte Carlo simulation to determine the probability of 

exposure. The results are specific to the survey simulated. The exact number, location, and configuration 

of future surveys are unknown, but yearly level-of-effort projections within planning areas for several 

survey types (including different sources) were provided by BOEM (Table 75). To evaluate the impact of 

exposure, a 24 h resetting time was chosen such that the received level of each animat was reset to zero 

after each 24 h evaluation period. In Test Scenario 1, it was found that location-specific characteristics of 

a survey, such as the acoustic propagation regime (e.g., shelf versus slope) or depth restrictions of animals 

had the greatest influence on the 24 h exposure estimates (as opposed to inherent modeling constraints, 

such as replacing animats as they move across the boundaries of the simulation). In Test Scenario 1, a 

method for scaling up simulation results to account for long-duration surveys was suggested. When using 

a resetting period (e.g., 24 h) the primary objective was to accurately estimate the average exposure 

within the reset period by ensuring that the simulation covered the various location-specific environments. 

The surveys may be conducted at any location within the planning area and occur at any time of the year, 

so the requirement was to adequately cover each area during the simulations. All survey simulations in 

Phase II are for 7 days and a sliding window approach was used to get the average 24 h exposure. The 

24 h exposure levels were then be scaled by the level of effort for each survey type to calculate the yearly 

exposure levels. 

7.1. Assumptions

In Phase II, the annual marine mammal acoustic exposure associated with geological and geophysical 

activity in the Gulf for the upcoming decade (2016–2025) used agent-based animal movement in 

simulated sound fields as Monte Carlo simulations to estimate the probability of exposure. The average 

number of animals exposed to levels exceeding threshold criteria in 24 h periods was scaled by the level 

of survey effort to determine the yearly number of potential individuals exceeding threshold for each 

species. The threshold criteria included the current NMFS criteria for potential injury (Level A 

harassment) and potential behavioral disruption (Level B harassment), and criteria for potentially 

injurious exposure based on Southall et al. (2007) and step-function criteria based on Wood et al. (2012) 

to evaluate potential behavioral disruption. 

The situations simulated are complex and evolving. The time period evaluated was 10 years of future 

survey efforts using representative surveys whose precise design, location, and time of performance are 

not known. There is presently a great of variety in survey and source configurations, and new 

configurations, sources, or use of sources are likely to be developed. The details of marine mammal 

density, distributions, and behavior patterns are imprecisely known and change as animal populations 

vary from year to year and location to location. 

When modeling complex situations with imperfect and incomplete data, assumptions must be made. 

When possible, the most representative data or methods were used. When necessary, the choices were

made to be conservative, i.e., were expected to produce an overestimate. Conservative assumptions in the 

Phase II modeling procedures include: 

• Environment parameters for acoustic propagation modeling: The environmental input parameters 

used for transmission loss modeling were from databases that provide averaged values with limited 

spatial and temporal resolution. Sound speed profiles are averaged seasonal values taken from many 

sample locations. Geoacoustic parameters (including sediment type, thickness, and reflectivity 
D-152 Acoustic Propagation and Marine Mammal Exposure Modeling

coefficients) and bathymetric grids are smoothed and averaged to characterize large regions of the 

seafloor. Local variability, which can be effected by weather, daily temperature cycles, and smallscale surface and sediment details, generally increases signal transmission loss, but was removed by 

these averaging processes. As a result, the transmission loss could in some cases be underestimated 

and, therefore, the received levels would be overestimated.

• Acoustic propagation modeling: The acoustic propagation model, MONM, used the horizontaldirection source level for all vertical angles. This may slightly underestimate the true sound levels in 

the vertical directional beam of the array that ensonifies a zone directly under the array. This is 

expected to be a minor effect given the small volume over which the reduction occurs. Additionally, 

there is a steep angle limitation in the parabolic equation (PE) model used in MONM that also leads 

to slightly reduced levels directly under the array. The wide-angle PE that is used in MONMN is 

accurate to at least 70 degrees. The reduced-level zone is a cone within a cone few degrees of vertical, 

which represents a relatively small water volume that should not significantly affect results.

• Acoustic filtering: Auditory weighting functions were used to filter the SEL and rms SPL sound 

fields. Type II M-weighting based on equal loudness perception (Finneran and Jenkins 2012) was 

used to filter the SEL sound field used to evaluate potential injury. Type I M-weighting (Southall et 

al. 2007) was used to filter the rms SPL sound fields that, primarily, were used to evaluate behavior. 

Type I and Type II M-weighting are approximations of the hearing ability of different species groups. 

As approximations, they do not necessarily represent any one individual animal. Type I M-weighting 

was meant as a conservative filter to account for the expected hearing range of the species groups 

(Southall et al. 2007). The use of Type I filtering is a conservative choice because these filter roll-off 

at high and low frequencies admit more sound energy than the corresponding audiograms would 

suggest. 

• Seasons modeled: To account for seasonal variation in propagation, winter (most conservative) and 

summer (least conservative) were both used to calculate exposure estimates. Propagation during 

spring and fall was found to be almost identical to the results for summer, so those seasons were 

represented with the summer results.

• Social grouping: Marine mammals often form social groups, or pods, that may number in the 

hundreds of animals. Although it was found that group size effects the distribution of the exposure 

estimates, the mean value of the exposure estimate was, generally, unchanged. Because the annual 

exposure estimates are meant to represent the aggregate of many surveys conducted in many locations 

at various times throughout the year, it is the mean exposure estimates that are most relevant. For this 

reason, social group size was not included in the exposure estimates.

• Mitigation: Mitigation procedures, such as shutting down an airgun array when animals are detected 

within an established exclusion zone, can reduce the injury exposure estimates. Mitigation 

effectiveness was found to be influenced by several factors, most importantly the ability to detect the 

animals within the exclusion zone. Some species are more easily detected than others, and detection 

probability varies with weather and observational set up. Weather during any seismic survey is 

unknown beforehand and detection probabilities are difficult to predict, so the effects of mitigation 

were not included in the exposure estimates. 

• Aversion: Aversion is a context-dependent behavioral response affected by biological factors, 

including energetic and reproductive state, sociality, and health status of individual animals. Animals 

may avoid loud or annoying sounds, which could reduce exposure levels. Currently, too little is 

known about the factors that lead to avoidance (or attraction) of sounds to include aversive behavior 

in the exposure estimates. 
Gulf of Mexico G&G Activities Programmatic EIS D-153

7.2. Phase II Modeling Methods

7.2.1. Acoustic Source Parameters

7.2.1.1. Airgun Array—8000 in3

The airgun array parameters Phase II were the same as those used in the Test Case (Section 6.1).

7.2.1.2. Single Airgun—90 in3

This acoustic source consists of a single Sercel airgun with a working firing volume of 90 in3. This source 

was used in a high-resolution geotechnical survey. The modeling assumed a tow depth of 4 m for the 

airgun, which was typical for this source type. The model assumed an operating pressure of 2000 psi. 

7.2.1.3. Boomer

The representative boomer system for geotechnical survey operations was

the Applied Acoustics AA301, based on a single plate with ~ 40 cm baffle 

diameter. Since the boomer plate has a circular piston surrounded by a 

rigid baffle, it has acoustic directivity and cannot be considered a pointlike source (Verbeek and McGee 1995). The beam pattern of a boomer 

plate shows directivity for frequencies above 1 kHz. The input energy for 

the AA301 boomer plate was up to 350 J per pulse or 1,000 J per second. 

The width of the pulse was 0.15–0.4 ms.

A source verification study was performed on a system similar to the 

AA301, the AP3000 system (Martin et al. 2012), which has a double-plate 

configuration operating at maximum input energy of 1,000 J. During the 

Martin et al. (2012) study, acoustic data were collected as close as 8 m to 

the source and directly below it. The data showed that the broadband source level for the system was 

203.3 dB 1 μPa @ 1 m rms SPL over a 0.2 ms window length and 172.6 dB re 1 μPa2

·s @ 1 m SEL. Data 

from the AP3000 were used in this study for modeling the boomer source. 

7.2.1.4. High Resolution Survey Sources

An autonomous underwater vehicle (AUV) may be used when performing high-resolution geotechnical 

surveys. Three types of survey equipment may be installed on the AUV:

• Multibeam echosounder 

• Side-scan sonar

• Sub-bottom profiler 

All three sources can operate concurrently, and typically do, although there may be times when one or 

two of the three is off. In our modeling, we assume that all three were operated concurrently. When 

sources were towed, the towing depth of the AUV was 4 m below the sea surface when the water depth 

was less than 100 m, and 40 m above the seafloor where water depth was more than 100 m. High 

resolution geophysical surveys are not always towed by an AUV, but in this modeling effort, the sources 

were assumed to be towed by an AUV. 
D-154 Acoustic Propagation and Marine Mammal Exposure Modeling

7.2.1.4.1. Multibeam Echosounder—Simrad EM2000

The representative multibeam echosounder system for geotechnical survey operations was the Simrad 

EM2000 (manufactured by Kongsberg Maritime AS). This device operates at 200 kHz (Kongsberg 2004). 

The system is equipped with an SM2000 transducer head that produces a single beam 17°× 88° wide. The 

multibeam forming occurs through receiving head and processing software. The nominal source level was

204 dB re 1 μPa @ 1 m. The per-pulse SEL depends on the pulse length. 

Operational parameters of the Simrad EM2000 multibeam echosounder system (Kongsberg 2004) are:

• Operating frequency: 200 kHz

• Beam width: 17°× 88° 

• Beam: 1 (straight down) 

• rms SPL: 203 dB re 1 μPa @ 1 m 

• Pulse length: 0.04–1.3 ms 

• Per pulse SEL: 160–175 dB re 1 μPa2·s @ 1 m 

7.2.1.4.2. Side-scan Sonar—EdgeTech 2200 IM

EdgeTech 2200 IM was a representative modular system designed for installation on an AUV. The 

system features full spectrum chirp side-scan capabilities that work at two frequencies concurrently, 120 

and 410 kHz. The side-scan sonar uses two side-mounted rectangular transducers, whose declination 

angle can be adjusted from 10° to 20° below the horizontal plain. The produced beam angle was

70° × 0.8° at 120 kHz and 70° × 0.5° at 410 kHz. At 120 kHz, we estimated the peak level at 210 dB re 1 

μPa @ 1 m; at 410 kHz, we estimated the peak level at 216 dB re 1 μPa @ 1 m (EdgeTech 2007). The 

pulse length was 8.3 ms at 120 kHz and 2.4 ms at 410 kHz.

7.2.1.4.3. Sub-bottom Profiler—EdgeTech 2200 IM with DW−424 

EdgeTech 2200 IM was a representative modular system designed for installation on an AUV. The 

system features DW−424, a full spectrum chirp sub-bottom profiler that produces a sweep signal in the 

frequency range from 4 to 24 kHz. The transmitter is a circular transducer directed straight down. The 

projected beamwidth varies from 15° to 25° depending on the emitted frequency. The source level was

200 dB re 1 μPa @ 1 m (EdgeTech 2007). The pulse length was 10 ms.

7.2.2. Survey Patterns

To estimate exposures, we considered two major survey types:

• Large area seismic

• Small-area, high-resolution geotechnical study

The primary differences between each survey were the energy of the sources, the size of the areas, and the 

density of the tracks.

Large area seismic surveys cover more than 1,000 square miles and include 2-D, 3-D NAZ, 3-D WAZ, 

and Coil types. An 8000 in3 airgun array was the primary source for the large area seismic surveys. The 

large surveys use a survey vessel with an average speed of 4.5–5 knots; it travels 200–220 linear km per 

day. No mitigation airguns were modeled, and airgun arrays were off during turns.
Gulf of Mexico G&G Activities Programmatic EIS D-155

Geotechnical study surveys cover an area less than 100 mi2 and use small airgun arrays (20–90 in3) and/or 

high-frequency electromechanical sources (sonars) installed on an AUV. The high resolution sources 

included a side-scan sonar, a sub-bottom profiler, and a multibeam echosounder. The survey vessel used 

in the large surveys travels at an average speed of 4 kts; it transits 180 km per day. 

Although parameters of the actual surveys could vary from one survey to the other, we selected specific 

parameters to model based on specifications provided by BOEM. The subsections herein describe the 

parameters of each survey type as they were modeled for Phase II.

Table 47. Summary of the Phase II surveys considered to determine the exposure estimates. The high resolution

sources were modeled independently.

Survey type Area Source Production lines lateral 

offset (km)

2-D 

10 × 30 blocks

48 × 145 km

2700 mi2

1 × 8000 in3 4.8

3-D NAZ 2 × 8000 in3 1 

3-D WAZ 4 × 8000 in3 1.2

Coil

12 × 12 blocks

58 × 58 km

1300 mi2

4 × 8000 in3 not applicable

Geotechnical

1 × 3 blocks

5 × 14.5 km

27 mi2

1 × 90 in3

high resolution sources

0.03

The survey schematics indicate the survey area (black rectangle) and vessel tracks. The tracks for 

different vessel are shown with different colors. To simplify the track design for the surveys using a 

racetrack fill-in method, the actual circular turn track was substituted with three straight legs: run-out, 

offset, and run-in sections. The run-in and run-out sections were 1 km long and extend beyond the survey 

area.

7.2.2.1. 2-D Seismic Survey

The 2-D seismic survey was performed with a single vessel towing a single large seismic array. The 

lateral spacing of the production lines was 4.8 km (Figure 105). The production lines were filled in with a 

racetrack fill-in method, skipping two tracks on the left side turn (15 km wide turn) and transitioning on 

to the adjacent line on the right side turn (5 km wide turn). Seven days of survey were simulated. The 

vessel speed was 4.5 kts (2.3 m/s). The shot interval was 21.6 s (50 m). The total length of the simulated 

track was ~ 1400 km. The number of simulated pulses was ~ 28,000. Constant towing azimuth, parallel to 

the long side of the survey box, was modeled for all shots.
D-156 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 105. Simulated portion of the track for the 2-D seismic survey.

7.2.2.2. 3-D Narrow Azimuth Seismic Survey

The 3-D NAZ seismic survey was performed with one or two vessels towing two identical large seismic 

arrays. The sources towed by the same vessel were operated in a flip-flop mode, i.e., for each shot 

position only one of the two produces a seismic pulse. In the two-vessel option, sources at each vessel 

produce seismic pulses simultaneously. The two-vessel option was simulated. Both vessels follow the 

same track, but were separated along the track by 6,000 m. The production lines were laterally spaced by 

1 km (Figure 106). The production lines were filled via a racetrack fill-in method with eight loops in each 

racetrack (7–8 km wide turn). Forty-nine lines were required to fully cover the survey area. The 7-day 

simulation covered ~ 20% of the complete survey. The vessel speed was 4.9 kts (2.5 m/s). The shot 

interval was 15 s (37.5 m) for each vessel. The total length of the simulated track was ~ 1500 km. The 

number of simulated pulses was ~ 80,000. 

Figure 106. Simulated portion of the track for the 3-D NAZ seismic survey.

7.2.2.3. 3-D Wide Azimuth Seismic Survey

The3-D WAZ seismic survey was performed with multiple vessels traveling along parallel tracks with 

some lateral and along the track offsets. The four-vessel option with seismic sources firing sequentially 

was simulated. The tracks of each vessel had the same geometry and had 1,200 m lateral offset. The 

vessels also had 500 m offset along the track. The lateral spacing of the same vessel’s production lines 

was 4.8 km and 1.2 km for the group (Figure 107). The production lines were filled in with a racetrack 

fill-in method with two loops in each racetrack (9.6 km wide turn). Forty lines were required to fully 

cover the survey area. The 7-day simulation covered ~ 85% of the complete survey. The vessel speed was
Gulf of Mexico G&G Activities Programmatic EIS D-157

4.5 kts (2.3 m/s). The shot interval was 86.4 s (200 m) for each vessel or 21.6 for the group. The total 

length of the simulated track was ~ 1400 km. The number of simulated pulses was ~ 28,000. 

Figure 107. Simulated portion of the track for the 3-D WAZ seismic survey.

7.2.2.4. Coil Seismic Survey

The Coil seismic survey was performed by multiple vessels that sailed a series of circular tracks with 

some angular separation while towing sources. The four-vessel option was simulated assuming 

simultaneous firing, and the track consisted of a series of circles with 12.5 km diameter (Figure 108). 

Once the vessel completes a full circle, it advanced to the next one along a tangential connection segment. 

The offset between the center of one circle and the next, either along-swath or between swaths, was 5 km. 

The full survey geometry consisted of two tracks with identical configuration with 1,200 m and 600 m 

offsets along X and Y directions, respectively. Two of the four vessels followed the first track with 180° 

separation; the other two vessels followed the second track with 180° separation relative to each other and 

90° separation relative to the first pair. One hundred circles per vessel pair were required to fully cover 

the survey area. The 7-day simulation covered ~ 30% of the complete survey. The vessel speed was 4.9 

kts (2.5 m/s). The shot interval was 20 s (50 m) for each vessel. The total length of the simulated track 

was ~ 1,500 km. The number of simulated pulses was ~ 120,000. 

Figure 108. Simulated portion of the track for the Coil seismic survey. 
D-158 Acoustic Propagation and Marine Mammal Exposure Modeling

7.2.2.5. High Resolution Geotechnical Survey

The geotechnical survey was performed in a similar fashion as the 2-D and 3-D surveys, only on 

significantly smaller survey areas and with denser production lines. 

A single vessel survey was considered for the simulation, towing either a 90 in3 airgun or a high 

resolution source equipped with a side-scan sonar, a sub-bottom profiler, and a multibeam echosounder. 

Production lines were laterally spaced 30 m (Figure 109) then filled in with a racetrack fill-in method 

where each racetrack has 20 loops (1.2 km wide turn). One hundred and sixty lines were required to fully 

cover the survey area. The 7-day simulation covered ~ 50% of the complete survey. The vessel speed was

4 kts (2 m/s). The shot interval was 10 s (20 m). The total length of the simulated track was ~ 1260 km. 

The number of simulated pulses was ~ 60,000. 

Figure 109. Simulated portion of the track for the geotechnical survey. 

7.2.3. Choice of Zone Boundaries

The size and shape of acoustic footprints from exploration surveys in the Gulf of Mexico are influenced 

by many parameters, but the strongest influencers are water depth and seabed slope. We divided the 

project area into three main bathymetric areas Shelf, Slope, and Deep. The Shelf extend from shore to 

100–200 m depths, where bathymetric relief is gradual; water depths on the continental shelf off Florida’s 

eastern coast are less than 200 m deep out to ~ 150 km from shore. The Slope starts at the Shelf’s outer 

boundary and extends into deeper water where the seabed relief is steeper and water deepens from 100–

200 m to 1500–2500 m over as little as a 50 km horizontal distance. The Slope ends at the Deep area, 

where, although water depths are more consistent than in the other areas, depths can vary from 2000–

3300 m. The subdivision depth definitions are Shelf: 0–200 m, Slope 200–2000 m, and Deep: > 2000 m.

Water depth influences species distribution in that there are distinctions from Shelf to Slope and from 

Slope to Deep. The maps in Appendix A show marine mammal distribution information from the Marine 

Geospatial Ecology Laboratory (Duke University) model (Roberts et al. In preparation; Section 7.2.6) and 

the subdivision depth boundary contours. The subdivision depths were chosen so that nominal marine 

mammal densities remain relatively constant over the resulting depth intervals. While different species 

prefer different depths, there are optimal depth breaks based on density distribution for the majority of 

species considered. The density of several species varies within the Shelf and Slope areas, but less so 

within the Deep area. Interestingly, the variation in animal density within the Shelf and Slope areas seems 

correlated with the orientation and differences in the widths of these areas over the east-west extent of the 

project area. The western region is characterized by a relatively narrow shelf and moderate-width slope. 

The central region has a moderate-width shelf and moderate-width slope, and the eastern region has a 

wide shelf and a very narrow slope. Because of these differences, areas were further division into lateral 

regions, which align with the previously defined BOEM Planning Area boundaries: West, Central, and 

East, was made in the Shelf and Slope areas. 
Gulf of Mexico G&G Activities Programmatic EIS D-159

Based on the physical properties of the project area and the distribution of its marine inhabitants, we 

divided the Gulf into 7 zones: 3 Shelf zones, 3 Slope zones, and 1 Deep zone. The southern edge of the 

Deep zone is defined by the U.S. Exclusive Economic Zone (EEZ) boundary. The zones boundaries were

defined by the 200 and 2000 m depth contours and the east-west boundary lines of BOEM’s Planning 

Areas (except for the Deep zone 7, which included portions of all three Planning Areas). The seven 

modeling zones, labelled “zones” are shown in Figure 110 along with the seven representative simulation 

locations—the numbered rectangles—which are discussed in the next section.

Figure 110. Gulf of Mexico project area. Black lines delineate the zones. Large, red rectangular boxes 

show the animal simulation extents for seismic surveys. Gray rectangles are the survey area 

extents for the 2-D and 3-D surveys. Pink squares are the survey extents of Coil surveys. 

Yellow stars show the acoustic modeling sites are along West, Central, and East transects.

7.2.3.1. Survey Extents

Within each of the seven zones, we defined a set of representative survey-simulation rectangles for each 

of the survey types discussed in Section 7.2.2. To avoid clutter in the diagram, Figure 110 shows the 

rectangles for the largest area surveys (2-D, 3-D, and Coil). Smaller area surveys (geotechnical surveys) 

were modeled near the center of the larger area surveys. During the seismic survey simulation, the source 

was moved within these rectangles. The sound produced, however, would ensonify an area larger than the 

rectangle. The corresponding animat simulation extents are shown as large, red boxes (Figure 110) and 

are discussed in more detail in Section 7.2.5. 

7.2.3.2. Acoustic Modeling Sites

As the acoustic energy from a source propagates, it is subject to a number of marine acoustic effects that 

depend on the ocean and bottom environment (see Section 5.2). We selected a set of 30 sites to calculate 

acoustic propagation loss grids as functions of source, range from the source, azimuth from the source, 

and receiver depth. We then used these grids as inputs to the acoustic exposure model. The 30 modeling 

sites (yellow stars in Figure 110) were grouped into three transects—Western, Central, and Eastern. The 

detailed geographic coordinates and water column depth of each acoustic modeling site are listed in 
D-160 Acoustic Propagation and Marine Mammal Exposure Modeling

Tables 48–51 for each transect. The coordinates of the center of survey locations are shown in Table 51. 

Even though these 30 modeling sites were not all located within the survey extents (boxes) discussed in 

the previous section, and Boxes 5 and 6 do not contain any individual modeling sites, the environmental 

parameters and acoustic propagation conditions represented by these 30 modeling sites were chosen to be 

representative of the prevalent acoustic propagation conditions within the survey extents (boxes). 

Table 48. Modeling sites along the West transect. 

Region Site Geographic coordinates UTM Zone 15 

coordinates

Water depth at source 

(m)

West-Shelf WS1 27° 24.77′ N 97° 5.78′ W 3038833 N 94877 E 25

WS2 27° 12.59′ N 96° 41.28′ W 3015053 N 134623 E 75

WS3 27° 5.40′ N 96° 26.93′ W 3001087 N 157967 E 150

West-Slope WM1 27° 1.94′ N 96° 20.06′ W 2994389 N 169162 E 300

WM2 26° 59.07′ N 96° 14.39′ W 2988854 N 178414 E 500

WM3 26° 54.23′ N 96° 4.82′ W 2979509 N 194032 E 750

WM4 26° 48.37′ N 95° 53.29′ W 2968231 N 212884 E 1000

WM5 26° 36.82′ N 95° 30.73′ W 2946105 N 249866 E 1500

West-Deep WD1 26° 13.56′ N 94° 45.86′ W 2901905 N 323744 E 2000

WD2 26° 12.73′ N 94° 44.29′ W 2900349 N 326344 E 2500

In the site names, S denotes a Shelf site, M a Slope (middle) site, and D a deep site.

Table 49. Modeling sites along Central transect. 

Region Site Geographic coordinates UTM Zone 15 

coordinates

Water depth at source 

(m)

Central-Shelf CS1 28° 35.84′ N 90° 34.27′ W 3165787 N 737510 E 25

CS2 28° 14.08′ N 90° 31.20′ W 3125696 N 743350 E 75

CS3 28° 6.06′ N 90° 30.07′ W 3110922 N 745502 E 150

Central-Slope CM1 28° 1.19′ N 90° 29.39′ W 3101933 N 746812 E 300

CM2 27° 56.60′ N 90° 28.74′ W 3093482 N 748043 E 500

CM3 27° 50.68′ N 90° 27.91′ W 3082567 N 749633 E 750

CM4 27° 39.14′ N 90° 26.30′ W 3061316 N 752729 E 1000

CM5 27° 7.28′ N 90° 21.85′ W 3002614 N 761280 E 1500

Central-Deep CD1 27° 5.87′ N 90° 21.66′ W 3000015 N 761658 E 2000

CD2 26° 46.56′ N 90° 18.98′ W 2964438 N 766841 E 2500

In the site names, S denotes a Shelf site, M a Slope (middle) site, and D a deep site.
Gulf of Mexico G&G Activities Programmatic EIS D-161

Table 50. Modeling sites along East transect. 

Region Site Geographic coordinates UTM Zone 15 

coordinates

Water depth at source 

(m)

East-Shelf ES1 27° 45.04′ N 83° 12.99′ W 3108253 N 1466813 E 25

ES2 27° 28.13′ N 84° 6.79′ W 3070008 N 1380052 E 75

ES3 27° 20.87′ N 84° 29.42′ W 3053885 N 1343477 E 150

East-Slope EM1 27° 12.89′ N 84° 54.04′ W 3036311 N 1303609 E 300

EM2 27° 10.97′ N 84° 59.89′ W 3032133 N 1294132 E 500

EM3 27° 10.13′ N 85° 2.47′ W 3030284 N 1289936 E 750

EM4 27° 9.30′ N 85° 5.00′ W 3028478 N 1285839 E 1000

EM5 27° 7.24′ N 85° 11.27′ W 3023996 N 1275672 E 1500

East-Deep ED1 27° 6.69′ N 85° 12.93′ W 3022805 N 1272969 E 2000

ED2 27° 6.40′ N 85° 13.79′ W 3022193 N 1271580 E 2500

In the site names, S denotes a Shelf site, M a Slope (middle) site, and D a deep site.

Table 51. Center coordinates of survey boxes. 

Box Geographic coordinates UTM Zone 15 coordinates Water depth at source (m)

1 26° 51.96′ N 96° 47.61′ W 2977239 N 123022 E 70

2 26° 53.66′ N 95° 31.78′ W 2977239 N 248731 E 1400

3 28° 36.94′ N 91° 17.84′ W 3166579 N 666464 E 30

4 27° 34.03′ N 90° 37.10′ W 3051524 N 735128 E 1000

5 26° 40.82′ N 88° 33.67′ W 2958720 N 941905 E 2400

6 28° 38.72′ N 86° 32.18′ W 3185841 N 1132432 E 500

7 27° 10.49′ N 83° 54.20′ W 3038730 N 1403352 E 70

7.2.4. Environmental Parameters

7.2.4.1. Bathymetry

Water depths throughout the modeled area were obtained from the National Geophysical Data Center’s 

U.S. Coastal Relief Model l (NGDC 2014) that extends up to about 200 km from the U.S. coast. These 

bathymetry data have a resolution of 3 arc-seconds (~ 80 × 90 m at the studied latitude). Bathymetry data 

for an area were extracted and re-gridded, using the minimum curvature method, onto a Universal 

Transverse Mercator (UTM) Zone 15 coordinate projection with a horizontal resolution of 50 × 50 m.

Two bathymetry grids were used for modeling. The first covered the West region (Boxes 1 and 2 in 

Figure 110); the second covered Central and East regions (Boxes 3–7 in Figure 110).

7.2.4.2. Multi-Layer Geoacoustic Profile

The top sections of the sediment cover in the Gulf of Mexico are represented by layers of unconsolidated 

sediments at least several hundred meters thick. The grain size of the surficial sediments follows the 

general trend for the sedimentary basins: the grain size of the deposited sediments decreases with the 

distance from the shore. For the Shelf zone, the general surficial bottom type was assumed to be sand, for 
D-162 Acoustic Propagation and Marine Mammal Exposure Modeling

the Slope zone silt, and for the Deep zone clay. In constructing a geoacoustic model for input to MONM 

(see 6.5.2.1.5 for required input parameters), a median value of φ was selected for each sediment type 

with the exception of the geoacoustic profile for the East-Shelf area. Because the grain size of the surficial 

sediment offshore Florida is consistently larger than in other shelf areas (Figure 50), we assumed φ equal 

to 1 for the sand in this zone.

Four sets of geoacoustic parameters were used in the acoustic propagation modeling: 

• Center-West Shelf (Table 52) 

• East Shelf (Table 53) 

• Slope (Table 54) 

• Deep (Table 55) 

Table 52. Shelf zone Center and West: Geoacoustic properties of the sub-bottom sediments as a function of depth, in 

meters below the seafloor (mbsf), for fine sand. Within each depth range, each parameter varies linearly within the 

stated range.

Depth below 

seafloor (m) Material

Densit

y 

(g/cm3)

P-wave 

speed 

(m/s)

P-wave 

attenuation 

(dB/λ)

S-wave 

speed 

(m/s)

S-wave attenuation 

(dB/λ)

0–20

Sand

φ=2

1.61 1610 0.62

200 0.76

20–50 1.7 1900 1.44

50–200 1.78 2090 1.77

200–600 1.87 2500 2.31

> 600 2.04 2500 2.67

Table 53. Shelf zone East: Geoacoustic properties of the sub-bottom sediments as a function of depth, in meters 

below the seafloor (mbsf), for medium-sand. Within each depth range, each parameter varies linearly within the 

stated range.

Depth below 

seafloor (m) Material Density (g/cm3) 

P-wave 

speed 

(m/s)

P-wave 

attenuation 

(dB/λ)

S-wave 

speed 

(m/s)

S-wave 

attenuation 

(dB/λ)

0–20

Sand

φ=1

1.7 1660 0.76

200 1.13

20–50 1.78 2040 1.68

50–200 1.87 2290 2.03

200–600 1.96 2500 2.56

> 600 2.04 2500 2.91
Gulf of Mexico G&G Activities Programmatic EIS D-163

Table 54. Slope zone: Geoacoustic properties of the sub-bottom sediments as a function of depth, in meters below 

the seafloor (mbsf), for medium silt. Within each depth range, each parameter varies linearly within the stated range.

Depth below 

seafloor (m) Material Density (g/cm3) 

P-wave 

speed 

(m/s)

P-wave 

attenuation 

(dB/λ)

S-wave 

speed 

(m/s)

S-wave attenuation 

(dB/λ)

0–20

Silt

φ=6

1.44 1515 0.33

150 0.22

20–50 1.7 1670 0.82

50–200 1.7 1750 1.07

200–600 1.87 1970 1.48

> 600 2.04 2260 1.82

Table 55. Deep zone: Geoacoustic properties of the sub-bottom sediments as a function of depth, in meters below 

the seafloor (mbsf), for medium clay. Within each depth range, each parameter varies linearly within the stated 

range.

Depth below 

seafloor (m) Material Density (g/cm3) 

P-wave 

speed 

(m/s)

P-wave 

attenuation 

(dB/λ)

S-wave 

speed 

(m/s)

S-wave attenuation 

(dB/λ)

0–20

Clay

φ=9

1.52 1472 0.17

100 0.06

20–50 1.7 1560 0.43

50–200 1.78 1610 0.56

200–600 1.87 1720 0.83

> 600 2.04 1890 1.05

7.2.4.3. Sound Speed Profiles

The sound speed profiles for the modeled sites were derived using the same source and method as 

described in Section 6.2.4. 

We investigated variation in the sound speed profile throughout the year and produced a set of 12 sound 

speed profiles, each representing one month, in the Shelf, Slope, and Deep zones (Figure 111). The set 

was divided into four seasons:

• Season 1: January, February, and March

• Season 2: April, May, and June 

• Season 3: July, August, and September

• Season 4: October, November, and December 

For each zone, a month was selected to represent the propagation conditions in the water column in each 

season (Table 56). 
D-164 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 111. Sound speed profiles at the (left) Shelf, (center) Slope, and (right) Deep zones, derived from 

data obtained from GDEM V 3.0 (Teague et al. 1990, Carnes 2009). 

Table 56. Representative months for each season and modeling zone.

Zone SSP GDEM location Season 1

(Jan-Mar)

Season 2

(Apr-Jun)

Season 3

(Jul-Sep)

Season 4

(Oct-Dec)

Shelf 25.5° N 90° W

Feb May

Aug Oct

Slope 27.25° N 90° W Sep Nov

Deep 28.5° N 90° W Aug Dec

ssp=sound speed profile

Acoustic fields were modeled using sound speed profiles for Season 1 and Season 3, and all three 

regions—East, Central, and West—used the same month. Profiles for Season 1 (February) provided the 

most conservative propagation environment because a surface duct, caused by upward refraction in the 

top 50–75 m, was present. Although a surface duct of this depth will not be able to prevent leakage of 

frequencies below 500–250 Hz (respectively), the ducting of frequencies above this cut off is important 

because these are the frequencies to which most marine mammals are most sensitive and the horizontal 

far-field acoustic projection from the airgun array seismic sources do have significant energy in this part 

of the spectrum. The modeling results obtained when the duct was present, therefore, represent the most 

precautionary propagation environment. Profiles for Season 3 (August or September) provided the least 

conservative results because they have weak to no sound channels at the surface and are strongly 

downward refracting in the top 200 m. Only the top 100 m of the water column are affected by the 

seasonal variation in the sound speed. 

The possibility of separately modeling the spring and fall seasons was investigated; however, the results 

for spring and fall are almost identical to the results for summer, which were used as a proxy for the 

spring and fall results. 
Gulf of Mexico G&G Activities Programmatic EIS D-165

7.2.4.3.1. Sound Speed Profiles for Box Centers

Sound speed profiles were gathered from the center of each modeling box for Seasons 1 and 3. Table 57

presents the months modeled for each of these seasons. Figures 112 and 113 show the sound speed 

profiles for Seasons 1 and 3, respectively.

Table 57. Modeling seasons for each box. 

Box Region Zone Season 1 Season 3

1 

West

Shelf

Feb

Aug

2 Slope Sep

3 

Central

Shelf Aug

4 Slope Sep

5 Deep Aug

6 

East Slope Sep

7 Shelf Aug

Figure 112. Sound speed profiles at modeling boxes, Season 1, derived from data obtained from GDEM 

V 3.0 (Teague et al. 1990, Carnes 2009).
D-166 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 113. Sound speed profiles at modeling boxes, Season 3, derived from data obtained from GDEM 

V 3.0 (Teague et al. 1990, Carnes 2009).

7.2.4.3.2. Sound Speed Profiles for Acoustic Modeling Sites along Transects

Sound speed profiles were obtained at three locations along each transect. Profiles were selected for 

Season 1 and Season 3. The months modeled for each season are presented in Table 58. Figures 114–116, 

show the sound speed profiles for transects in the West, Central, and East regions respectively.

Table 58. Modeling seasons for the sites along transects. 

Region Zone Season 1 Season 3

West

Shelf

Feb

Aug

Slope Sep

Shelf Aug

Central

Shelf Aug

Slope Sep

Shelf Aug

East

Shelf Aug

Slope Sep

Deep Aug
Gulf of Mexico G&G Activities Programmatic EIS D-167

Figure 114. Sound speed profiles along the West transect, derived from data obtained from GDEM V 3.0 

(Teague et al. 1990, Carnes 2009).
D-168 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 115. Sound speed profiles along Central transect, derived from data obtained from GDEM V 3.0 

(Teague et al. 1990, Carnes 2009).
Gulf of Mexico G&G Activities Programmatic EIS D-169

Figure 116. Sound speed profiles along East transect, derived from data obtained from GDEM V 3.0 

(Teague et al. 1990, Carnes 2009).

7.2.5. 3MB Simulation Areas

The extents of the surveys were determined (Section 7.2.3.1), and the boxes surrounding the surveys for 

animat movement simulation were introduced (Figure 110, large red rectangles). These animat simulation 

boxes set the geographic limits of the 3MB simulation defined by the 3MB bathymetry file input. For 

large seismic surveys, potential behavioral disruption and NMFS criteria (for injury and behavior) were 

evaluated using the boxes shown Figure 110. Because potential injury assessed with SEL and peak SPL 

exposure criteria occurs at higher received levels (i.e., closer to the source) than those used to assess 

behavioral disruption and the NMFS criteria, the injury exposure boxes can be smaller than the behavioral 

disruption boxes. The extents of the simulation boxes for the surveys are described below. 

7.2.5.1. Large Seismic Surveys

For the large seismic surveys, the injury simulation boxes extend outward (north, south, east, and west) 

by 10 km from the survey limits (Table 59), a distance over which the unweighted received levels drop 

below 160 dB re 1 μPa2·s SEL for a single shot. This injury simulation box was therefore much larger 

than the area that would enclose received levels less than the high frequency-weighted 161 dB re 1 μPa2·s 

SEL criterion, even for multiple shot accumulation. The behavior simulation boxes, on the other hand, 

extend outward by 50 km from the survey limits (Table 60), a distance necessary to ensure that the animat 

movement modeling extends out to where the M-weighted received levels drop to 120 dB re 1 μPa rms 

SPL or lower, and below 160 dB re 1 μPa2·s SEL for unweighted received levels.

Since injury events are intrinsically rare, improved statistical assessment was achieved by using a higher 

animat modeling density, and prorating the final exposure estimates by the real-world species density in 
D-170 Acoustic Propagation and Marine Mammal Exposure Modeling

the final stage of the statistical analysis. The smaller injury simulation boxes, relative to the behavior 

simulation boxes, allows for higher modeling density to be used for injury without incurring a 

corresponding additional cost in computation time because the geographical area was smaller.

Because the 3MB modeling of animat movement requires significant computer resources, and lengthy 

computer run times, the same 3MB animat movement model results files were reused for the different 

large seismic surveys (although different for injury and behavior simulations), i.e., the 2-D, 3-D, and Coil 

surveys. Based on range to the received level limits, the animal simulation areas were large enough to 

satisfy the geographical extent requirements in each of the four cardinal directions.

Table 59. Geographic extent of the animat movement boxes for behavior simulation with the large seismic surveys.

Box South latitude limit 

(degrees)

North latitude limit 

(degrees)

West longitude 

limit (degrees)

East longitude limit 

(degrees)

1 25.7385828 27.9873227 −97.697267 −96.035589

2 25.7750253 28.0114215 −96.324378 −94.686512

3 27.8386100 29.2946720 −92.552590 −90.027197

4 26.7853837 28.2521000 −91.865786 −89.357844

5 25.8836263 27.3817193 −89.809799 −87.302241

6 27.8304152 29.3656712 −87.819438 −85.244178

7 26.0299683 28.3155107 −84.739032 −82.985553

Table 60. Geographic extent of the animat movement boxes for injury simulation with the large seismic surveys.

Box South latitude limit 

(degrees)

North latitude limit 

(degrees)

West longitude 

limit (degrees)

East longitude limit 

(degrees)

1 26.0989428 27.6269627 −97.29331627 −96.43953973

2 26.1353853 27.6510615 −95.92031909 −95.09057091

3 28.1989700 28.9343120 −92.14227901 −90.43750799

4 27.1457437 27.8917400 −91.45945302 −89.76417698

5 26.2439863 27.0213593 −89.40666570 −87.70537430

6 28.1907752 29.0053112 −87.40900447 −85.65461153

7 26.3903283 27.9551507 −84.33396603 −83.39061897

7.2.5.2. High-resolution Surveys

The received levels for the sources used in the high-resolution surveys drop off much more quickly with 

range than for the seismic survey sources discussed above. If we used the same approach for highresolution sources as was used for large seismic surveys, very small boxes would result, which would 

prevent the animat movements from realistically behaving. Consequently, the 3MB simulation boxes to 

the high-resolution surveys were extended to 10 km from the center of the survey in each cardinal 

direction (Table 61), a much larger distance than that required for the received level conditions, but one 

that supports more realistic animal movements. Consequently, the behavior and injury simulations for 

high-resolution surveys used the same boxes, although, as discussed in the section above, a higher animat 

modeling density was used to simulate injury. 
Gulf of Mexico G&G Activities Programmatic EIS D-171

Table 61. Geographic extent of the animat movement boxes for both behavior and injury simulation with the highresolution surveys.

Box South latitude limit 

(degrees)

North latitude limit 

(degrees)

West longitude 

limit (degrees)

East longitude limit 

(degrees)

1 26.77588 26.95606 −96.8939 −96.6930

2 26.80408 26.98447 −95.6303 −95.4292

3 28.52530 28.70575 −91.3996 −91.1951

4 27.47697 27.65738 −90.7197 −90.5173

5 26.59023 26.77026 −88.6614 −88.4610

6 28.55562 28.73499 −86.6380 −86.4346

7 27.08567 27.26396 −84.0030 −83.8037

7.2.6. Animal Densities

Cetacean density estimates (animals/km2) were obtained using the Marine Geospatial Ecology Laboratory 

(Duke University) model Roberts et al. (In preparation), preliminary results. These estimates were 

produced with distance sampling methodology (Buckland et al. 2001) from 195,000 linear km of 

shipboard and aerial surveys conducted by NOAA’s Southeast Fisheries Science Center (SEFSC) in the 

Gulf of Mexico from 1992–2009. For each species, the count of animals per 10 km survey segment was 

modeled using a Horvitz-Thompson-like estimator (Marques and Buckland 2004, Miller et al. 2013). 

Species-specific detection functions were fitted using observation-level covariates such as Beaufort sea 

state, sun glare, and group size. When possible, availability and perception bias were estimated on a perspecies basis using results from the scientific literature. After the sightings were corrected for 

detectability, availability, and perception bias, statistical regressions were used to model counts of 

animals per segment.

The density of frequently-sighted species were modeled with generalized additive models based on a 

collection of physiographic, physical oceanographic, and biological productivity predictor variables that 

plausibly relate to cetacean habitat. Both contemporaneous and climatological predictors were tested. 

Models were fitted to survey data and insignificant predictors were dropped from the models (Wood 

2006). Final models were predicted across a time series of grids at 10 km resolution and averaged to 

produce a single surface representing mean density at each 10 km × 10 km grid square or cell. 

There was insufficient data for infrequently seen species to model density from habitat variables. Instead, 

the geographic area of probable habitat was delineated from the scientific literature; patterns in the 

available sightings and density were estimated from the survey segments that occurred there using a 

statistical model that had no covariates. This model ran over the entire extent of the habitat area, yielding 

a uniform density estimate for the area.

Marine mammal density estimates for each species in the modeling zones are shown in Tables 62–68. 
D-172 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 62. Zone 1 Marine mammal density estimates. 

Species Movement 

surrogate

Seeding adjustment Density estimate

Injury Behavior Min Max Mean STD

Atlantic spotted 

dolphins

1.0 0.9988 0.000002 65.932686 19.561691 17.154286

Beaked whales 1.0 0.9879 0.000000 0.004306 0.000107 0.000402

Common 

bottlenose

dolphins

1.0 0.9988 10.718610 143.330322 37.130025 20.297288

Bryde’s whales 0.1661 0.2849 0.000000 0.167721 0.012267 0.035798

Clymene 

dolphins 

Pantropical 

spotted 

dolphins 

1.0 0.9988 0.000000 0.080756 0.000785 0.004739

False killer 

whales

Roughtoothed 

dolphins

1.0 0.9988 0.000000 0.748148 0.123816 0.278033

Fraser’s 

dolphins 

Short-finned 

pilot whales

1.0 0.9988 0.000000 0.388778 0.064342 0.144481

Killer whales 1.0 0.9988 0.000003 0.002641 0.000392 0.000507

Kogia Short-finned 

pilot whales

1.0 0.9988 0.000000 0.381413 0.016379 0.046385

Melon-headed 

whales

Short-finned 

pilot whales

1.0 0.9988 0.000000 0.071767 0.002691 0.008428

Pantropical 

spotted dolphins 

1.0 0.9988 0.000000 2.683713 0.111202 0.350165

Pygmy killer 

whales

Roughtoothed 

dolphins

1.0 0.9988 0.000000 0.026950 0.001253 0.003460

Risso’s dolphins 1.0 0.9634 0.000000 0.489424 0.017854 0.055393

Rough-toothed 

dolphins

1.0 0.9988 0.000000 0.857693 0.406426 0.109876

Short-finned 

pilot whales

1.0 0.9988 0.078137 0.017168 0.000262 0.001151

Sperm whales* 0.1 0.1 0.000000 0.004952 0.000150 0.000473

Spinner 

dolphins

Pantropical 

spotted 

dolphins

1.0 0.9988 0.000000 2.888299 0.018491 0.124570

Striped dolphins

Pantropical 

spotted 

dolphins

1.0 0.9988 0.000000 0.180768 0.002602 0.012559

* Due to depth restrictions, in Zone 1 no sperm whale animats were seeded (placed in the model area) for injury and behavior.

For this case, it was necessary to make a seeding adjustment = 0.1 to avoid a division by 0 error, but the dummy value did not 

contribute to the overall exposure estimate. See Section 7.2.7.1 for more information about seeding.
Gulf of Mexico G&G Activities Programmatic EIS D-173

Table 63. Zone 2 Marine mammal density estimates.

Species Movement 

surrogate

Seeding adjustment Density estimate

Injury Behavior Min Max Mean STD

Atlantic spotted 

dolphins

0.9532 0.8597 0.000001 30.319336 7.456256 9.462431

Beaked whales 0.9149 0.82 0.000000 0.000281 0.000003 0.000018

Common 

bottlenose

dolphins

0.9532 0.8597 8.439063 113.845413 53.082960 22.977138

Bryde’s 

whales* 

0.1 0.2103 0.000000 0.028985 0.000164 0.001293

Clymene 

dolphins

Pantropical 

spotted 

dolphins

0.9532 0.8597 0.000000 0.000935 0.000002 0.000035

False killer 

whales

Roughtoothed 

dolphins

0.9532 0.8597 0.000000 0.748148 0.028735 0.143780

Fraser’s 

dolphins

Short-finned 

pilot whales

0.9532 0.8597 0.000000 0.388778 0.014932 0.074716

Killer whales 0.9532 0.8597 0.000004 0.001135 0.000177 0.000192

Kogia Short-finned 

pilot whales

0.9532 0.8597 0.000000 0.043914 0.000937 0.004897

Melon-headed 

whales

Short-finned 

pilot whales

0.9532 0.8597 0.000000 0.011606 0.000181 0.000979

Pantropical 

spotted dolphins

0.9532 0.8597 0.000000 0.131169 0.002317 0.012380

Pygmy killer 

whales

Roughtoothed 

dolphins

0.9532 0.8597 0.000000 0.004356 0.000078 0.000413

Risso’s dolphins 0.7538 0.7252 0.000000 0.071479 0.000835 0.004760

Rough-toothed 

dolphins

0.9532 0.8597 0.154323 0.887101 0.394670 0.083382

Short-finned 

pilot whales

0.9532 0.8597 0.000000 0.002055 0.000010 0.000086

Sperm whales* 0.1 0.1 0.000000 0.000350 0.000007 0.000035

Spinner 

dolphins

Pantropical 

spotted 

dolphins

0.9532 0.8597 0.000000 0.000022 0.000000 0.000001

Striped dolphins Pantropical 

spotted 

dolphins

0.9532 0.8597 0.000000 0.001711 0.000025 0.000141

* Due to depth restrictions, in Zone 2 no sperm whale animats were seeded (placed in the model area) for injury and behavior and 

no Bryde’s whale animats were seeded for injury. For these cases, it was necessary to make a seeding adjustment = 0.1 to avoid a 

division by 0 error, but the dummy values did not contribute to the overall exposure estimates. See Section 7.2.7.1 for more 

information about seeding.
D-174 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 64. Zone 3 Marine mammal density estimates.

Species Movement 

surrogate

Seeding adjustment Density estimate

Injury Behavior Min Max Mean STD

Atlantic spotted 

dolphins

0.9916 0.9696 0.000071 27.600784 8.191627 7.035238

Beaked whales 0.9795 0.9522 0.000000 0.000140 0.000001 0.000012

Common 

bottlenose

dolphins

0.9916 0.9522 8.936208 79.201904 39.405915 14.535437

Bryde’s whales 0.0759 0.2908 0.000000 0.007863 0.000041 0.000375

Clymene 

dolphins

Pantropical 

spotted 

dolphins

0.9916 0.9696 0.000000 0.000152 0.000000 0.000007

False killer 

whales

Roughtoothed 

dolphins

0.9916 0.9696 0.000000 0.748148 0.013218 0.098562

Fraser’s 

dolphins

Short-finned 

pilot whales

0.9916 0.9696 0.000000 0.388778 0.006869 0.051218

Killer whales 0.9916 0.9696 0.000006 0.000913 0.000191 0.000162

Kogia Short-finned 

pilot whales

0.9916 0.9696 0.000000 0.024987 0.000187 0.001645

Melon-headed 

whales

Short-finned 

pilot whales

0.9916 0.9696 0.000000 0.006796 0.000062 0.000496

Pantropical 

spotted dolphins

0.9916 0.9696 0.000000 0.069956 0.000597 0.004851

Pygmy killer 

whales

Roughtoothed 

dolphins

0.9916 0.9696 0.000000 0.002749 0.000029 0.000223

Risso’s dolphins 0.9073 0.895 0.000000 0.043172 0.000297 0.002568

Rough-toothed 

dolphins

0.9916 0.9696 0.277675 0.765203 0.396268 0.060134

Short-finned 

pilot whales

0.9916 0.9696 0.000000 0.001161 0.000005 0.000054

Sperm whales* 0.1 0.1 0.000000 0.000212 0.000002 0.000018

Spinner 

dolphins

Pantropical 

spotted 

dolphins

0.9916 0.9696 0.000000 0.000001 0.000000 0.000000

Striped dolphins Pantropical 

spotted 

dolphins

0.9916 0.9696 0.000000 0.003908 0.000030 0.000310

* Due to depth restrictions, in Zone 3 no sperm whale animats were seeded (placed in the model area) for injury and behavior.

For this case, it was necessary to make a seeding adjustment = 0.1 to avoid a division by 0 error, but the dummy value did not 

contribute to the overall exposure estimate. See Section 7.2.7.1 for more information about seeding.
Gulf of Mexico G&G Activities Programmatic EIS D-175

Table 65. Zone 4 Marine mammal density estimates.

Species Movement 

surrogate

Seeding adjustment Density estimate

Injury Behavior Min Max Mean STD

Atlantic spotted 

dolphins

1.0 1.0 0.000002 40.318748 2.781758 6.191489

Beaked whales 1.0 1.0 0.000000 4.682173 0.725775 1.107739

Common 

bottlenose

dolphins

1.0 1.0 0.003873 66.720116 11.553444 12.482596

Bryde’s whales 1.0 0.9502 0.000000 0.167727 0.035179 0.055666

Clymene 

dolphins

Pantropical 

spotted 

dolphins

1.0 1.0 0.000000 7.119437 0.914148 1.012023

False killer 

whales

Roughtoothed 

dolphins

1.0 1.0 0.000000 0.748148 0.727735 0.121883

Fraser’s 

dolphins

Short-finned 

pilot whales

1.0 1.0 0.000000 0.388778 0.378170 0.063337

Killer whales 1.0 1.0 0.000090 0.094036 0.013264 0.015548

Kogia Short-finned 

pilot whales

1.0 1.0 0.000000 2.564462 0.958299 0.613179

Melon-headed 

whales

Short-finned 

pilot whales

1.0 1.0 0.000000 4.612887 1.181967 1.227168

Pantropical 

spotted dolphins

1.0 1.0 0.000000 88.489113 21.767563 19.221821

Pygmy killer 

whales

Roughtoothed 

dolphins

1.0 1.0 0.000000 0.691082 0.296539 0.253896

Risso’s dolphins 1.0 1.0 0.000000 10.243490 1.419280 1.445694

Rough-toothed 

dolphins

1.0 1.0 0.501328 1.931466 0.961959 0.308922

Short-finned 

pilot whales

1.0 1.0 0.000000 5.891473 0.685525 0.842500

Sperm whales 0.184 0.3378 0.000000 2.049208 0.482223 0.480525

Spinner 

dolphins

Pantropical 

spotted 

dolphins

1.0 1.0 0.000000 145.747696 11.762649 17.414109

Striped dolphins Pantropical 

spotted 

dolphins

1.0 1.0 0.000000 5.765086 0.799246 0.882350
D-176 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 66. Zone 5 Marine mammal density estimates.

Species Movement 

surrogate

Seeding adjustment Density estimate

Injury Behavior Min Max Mean STD

Atlantic spotted 

dolphins

1.0 1.0 0.000013 26.744694 2.031142 4.981907

Beaked whales 1.0 1.0 0.000000 3.432981 1.080930 0.851019

Common 

bottlenose

dolphins

1.0 1.0 0.025899 46.434166 5.728691 8.809752

Bryde’s whales 1.0 0.9525 0.000000 0.167701 0.014526 0.039290

Clymene 

dolphins

Pantropical 

spotted 

dolphins

1.0 1.0 0.000000 15.461932 3.416620 3.148363

False killer 

whales

Roughtoothed 

dolphins

1.0 1.0 0.000000 0.748148 0.726846 0.124434

Fraser’s 

dolphins

Short-finned 

pilot whales

1.0 1.0 0.000000 0.388778 0.377708 0.064662

Killer whales 1.0 1.0 0.000159 0.056221 0.020153 0.014145

Kogia Short-finned 

pilot whales

1.0 1.0 0.000000 1.972867 0.726706 0.450570

Melon-headed 

whales

Short-finned 

pilot whales

1.0 1.0 0.000000 3.859135 2.209811 1.321709

Pantropical 

spotted dolphins

1.0 1.0 0.000000 31.898088 15.504281 9.582240

Pygmy killer 

whales

Roughtoothed 

dolphins

1.0 1.0 0.000000 0.691082 0.456866 0.269419

Risso’s dolphins 1.0 1.0 0.000000 7.244700 0.972485 1.026923

Rough-toothed 

dolphins

1.0 1.0 0.484941 1.574484 1.050021 0.185273

Short-finned 

pilot whales

1.0 1.0 0.000000 3.430244 0.639206 0.665957

Sperm whales 0.6644 0.6107 0.000000 2.049208 0.725159 0.527590

Spinner 

dolphins

Pantropical 

spotted 

dolphins

1.0 1.0 0.000000 66.322189 4.154421 8.152655

Striped dolphins Pantropical 

spotted 

dolphins

1.0 1.0 0.000000 4.547289 1.334442 0.985099
Gulf of Mexico G&G Activities Programmatic EIS D-177

Table 67. Zone 6 Marine mammal density estimates.

Species Movement 

surrogate

Seeding adjustment Density estimate

Injury Behavior Min Max Mean STD

Atlantic spotted 

dolphins

1.0 1.0 0.000007 17.078234 1.273500 3.317500

Beaked whales 1.0 1.0 0.000000 2.336602 0.832344 0.536911

Common 

bottlenose

dolphins

1.0 1.0 0.030806 24.043407 3.342733 5.111497

Bryde’s whales 1.0 0.9034 0.000000 0.167480 0.013691 0.037372

Clymene 

dolphins

Pantropical 

spotted 

dolphins

1.0 1.0 0.000000 16.132580 4.262516 3.869130

False killer 

whales

Roughtoothed 

dolphins

1.0 1.0 0.000000 0.748148 0.735816 0.095258

Fraser’s 

dolphins

Short-finned 

pilot whales

1.0 1.0 0.000000 0.388778 0.382369 0.049501

Killer whales 1.0 1.0 0.000358 0.053226 0.019773 0.012304

Kogia Short-finned 

pilot whales

1.0 1.0 0.000000 1.100742 0.411093 0.228572

Melon-headed 

whales

Short-finned 

pilot whales

1.0 1.0 0.000000 3.280858 1.890231 1.024283

Pantropical 

spotted dolphins

1.0 1.0 0.000000 16.103422 9.864202 5.300093

Pygmy killer 

whales

Roughtoothed 

dolphins

1.0 1.0 0.000000 0.691080 0.476313 0.254439

Risso’s dolphins 1.0 1.0 0.000000 3.041948 0.794562 0.616821

Rough-toothed 

dolphins

1.0 1.0 0.420462 1.595734 0.997906 0.183769

Short-finned 

pilot whales

1.0 1.0 0.000000 5.996468 1.249850 1.434598

Sperm whales 0.7368 0.5215 0.000000 1.356392 0.486587 0.286136

Spinner 

dolphins

Pantropical 

spotted 

dolphins

1.0 1.0 0.000000 2.337054 0.236570 0.284845

Striped dolphins Pantropical 

spotted 

dolphins

1.0 1.0 0.000000 1.833318 1.091651 0.565132
D-178 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 68. Zone 7 Marine mammal density estimates.

Species Movement 

surrogate

Seeding adjustment Density estimate

Injury Behavior Min Max Mean STD

Atlantic spotted 

dolphins

1.0 1.0 0.000000 0.001134 0.000004 0.000027

Beaked whales 1.0 1.0 0.222212 3.113844 0.519543 0.286857

Common 

bottlenose

dolphins

1.0 1.0 0.001245 1.554906 0.027482 0.067843

Bryde’s whales 1.0 1.0 0.000000 0.000004 0.000000 0.000000

Clymene 

dolphins

Pantropical 

spotted 

dolphins

1.0 1.0 0.005837 16.310186 2.627719 3.204962

False killer 

whales

Roughtoothed 

dolphins

1.0 1.0 0.748148 0.748148 0.748148 0.000000

Fraser’s 

dolphins

Short-finned 

pilot whales

1.0 1.0 0.388778 0.388778 0.388778 0.000000

Killer whales 1.0 1.0 0.023988 0.101078 0.077865 0.016385

Kogia Short-finned 

pilot whales

1.0 1.0 0.151227 0.825459 0.342218 0.062230

Melon-headed 

whales

Short-finned 

pilot whales

1.0 1.0 0.618728 4.204332 1.533612 0.671281

Pantropical 

spotted dolphins

1.0 1.0 10.890163 46.524502 26.087947 6.013833

Pygmy killer 

whales

Roughtoothed 

dolphins

1.0 1.0 0.643905 0.691082 0.661113 0.013441

Risso’s dolphins 1.0 1.0 0.083161 2.332364 0.419790 0.237456

Rough-toothed 

dolphins

1.0 1.0 0.385164 1.895322 0.798816 0.276520

Short-finned 

pilot whales

1.0 1.0 0.003767 0.771689 0.121555 0.104179

Sperm whales 1.0 1.0 0.354441 1.140214 0.467025 0.131315

Spinner 

dolphins

Pantropical 

spotted 

dolphins

1.0 1.0 0.043222 24.800802 0.612156 1.245325

Striped dolphins Pantropical 

spotted 

dolphins

1.0 1.0 0.541343 2.608293 1.365036 0.429627
Gulf of Mexico G&G Activities Programmatic EIS D-179

7.2.6.1. Marine Mammal Density Estimates in Modeling Zones

The Marine Geospatial Ecology Laboratory (Duke University) model (Roberts et al. In preparation) is a 

GIS-compatible raster of density estimates in 10 km2

 × 10 km2 squares. The minimum, maximum, mean, 

and the standard deviation of the mean were obtained for each species in each zone. These density 

estimates and depth-restricted density adjustments (Section 7.2.7.1) are shown in Tables 62–68; Appendix 

A shows distribution maps. 

7.2.7. Animal Movement: JEMS

The JASCO Exposure Modeling System (JEMS) combines animal movement data, the output from 3MB 

(Section 5.3), with pre-computed acoustic fields (Sections 5.1–5.2). The JEMS output was the timehistory of received levels and slant ranges (the three dimensional distance between the animat and the 

source) for all animats of the 3MB simulation. Animat received levels and slant ranges are used to 

determine the risk of acoustic exposure. JEMS can use any acoustic field data provided as a 3-D radial 

grid (e.g., N×2-D MONM output). Source movement and shooting patterns can be defined, and multiple 

sources and sound fields used. For impulsive sources, a shooting pattern based on movement can be 

defined for each source, with shots distributed along the vessel track by location (or time). Because the 

acoustic environment varies with location, acoustic fields are pre-computed at selected sites in the 

simulation area and JEMS chooses the closest modeled site to the source at each time step. 

7.2.7.1. Depth-restricted Density Adjustment

The number of animats that 3MB initially places, or seeds, in a simulation was based on the specified 

animat density (in units of animats per km2

) and simulation area. The model establishes a grid to cover 

the simulation area, then examines the bathymetry in the simulation area and determines the number of 

grid points where the water depth is greater than zero. The number of grid points where the water depth is 

greater than zero provides an estimate of the working area and the number of animats to seed is calculated 

from the working area and the animat’s specified density. 3MB randomly selects grid points and evaluates 

the points based on the suitability for the animat species. For example, a depth restriction may be set that 

eliminates grid points too shallow for seeding a particular species. If the grid point is accepted, an animat 

is placed at that grid point (at a random depth location within the species-defined depth range) and 3MB 

decreases its animat seeding quota by one. The loop continues until the predetermined number animats is 

successfully seeded. For species whose definition accepts seeding locations in all water depths greater 

than zero, a uniform animat seeding density equal to the specified density is achieved in the simulation 

area. For species with depth restrictions, such as sperm whales that are restricted to water deeper than 

1000 m, the number of animats determined by the working area and specified density will be concentrated 

within the area of the simulation that meets the restriction and their density effectively increased in that 

portion. The animat modeling density is a key value when calculating the exposure estimates, so exposure 

estimates are skewed if concentrating the animats increases the density. To avoid this problem, we 

calculated separately the number of acceptable grid points (based on the percentage of the working area 

that meets the depth restriction) and used this information to calculate an adjustment factor to pro-rate the 

exposure estimates.

7.2.7.2. Evaluation Time Period

Animat exposure histories were processed to calculate the number of animats exposed to levels exceeding 

threshold (the number of exposures). The time interval over which the counting was done must be 

defined. While there is no consensus on the time interval (see time interval effects in Section 6.5.1: Test 

Scenario 1), a 24 h period is often used (Southall et al. 2007). For this analysis, seven-day simulations 
D-180 Acoustic Propagation and Marine Mammal Exposure Modeling

were run and the exposures estimated in 24 h windows within the seven days. The first 24 h window 

begins at the start of the simulation and each subsequent window is advanced by 4 h. In this slidingwindows approach, 42 exposure estimate samples are obtained for each seven-day simulation. The mean 

value is then used as the 24 h exposure estimate for that survey.

7.2.7.3. Annual Aggregate Estimates 

This analysis estimated the annual number of exposures for each species for each year for each type of 

source for the entire Gulf. To get these annual exposure estimates, the 24 h exposure estimates were 

scaled by the number of expected survey days. BOEM provided projections of survey level of effort 

(shown in Table 75) for each survey type in each year (2016–2025) in BOEM’s Gulf of Mexico Planning 

Areas (eastern, central, and western; divided into shallow and deep zones). These survey projections were 

used to scale the 24 h exposure estimates from simulations in the appropriate locations. 

7.3. Phase II Modeling Results

7.3.1. Acoustic Sources: Levels and Directivity

7.3.1.1. Airgun Sources

We used the Airgun Array Source Model (AASM) to model the pressure signatures of the individual 

airguns and the composite 1/3-octave-band source levels of the arrays, as functions of azimuthal angle in 

the horizontal plane (Section 5.1.1). While AASM accounts for effects of source depth on bubble 

interactions, the surface-reflected signal (i.e., surface ghost) was not included in the far-field source 

signatures. The acoustic propagation models account for surface reflections, which are a property of the 

medium, not the source. 

7.3.1.1.1. Airgun Array—8000 in3

The broadside (perpendicular to the tow direction) and endfire (parallel to the tow direction) horizontal 

overpressure signatures (Figure 117a) consist of a strong primary peak, related to the initial firing of the 

airguns, followed by a series of pulses associated with the bubble oscillations. The broadside and endfire 

power spectrum levels were highest at frequencies below 500 Hz (Figure 117b). Frequency-dependent 

peaks and nulls in the spectrum were caused by interference among airguns in the array; they reflect the 

volumes and relative locations of the airguns. The broadband horizontal source levels are shown in 

Table 69. 

As discussed in Section 5.1.1, directivity in the sound field was most noticeable at mid-frequencies. 

Maximum (horizontal) 1/3-octave-band source levels over all azimuths are shown in Figure 118. 

Horizontal 1/3-octave-band source levels are shown as a function of band center frequency and azimuth 

in Figure 119. 
Gulf of Mexico G&G Activities Programmatic EIS D-181

(a) (b) 

Figure 117. Predicted (a) overpressure signature and (b) power spectrum in the broadside and endfire 

(horizontal) directions, for a generic 8000 in3

 airgun array towed at a depth of 8 m.

Table 69. Horizontal source level specifications for a generic 8000 in3 airgun array.

Direction Zero-to-peak SPL

(dB re 1 μPa @ 1 m)

SEL

(dB re 1 μPa2 @ 1 m)

10 Hz to 5 kHz

Broadside 248.1 225.7

Endfire 255.2 231.8

Figure 118. Maximum 1/3-octave-band source level in the horizontal plane for a generic 8000 in3 airgun 

array. The maximum over all modeled azimuths is shown for each 1/3-octave-band. 
D-182 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 119. Directionality of predicted horizontal source levels for a generic 8000 in3 airgun array. Source 

levels in dB re 1 μPa2

·s are shown as a function of azimuth for the center frequencies of the 

1/3-octave-bands modeled; frequencies are indicated above the plots. Tow direction was to 

the right.

7.3.1.1.2. Single Airgun—90 in3

Since the source consists of one gun, the acoustic wave is omnidirectional and has virtually the same 

characteristics in all directions. The overpressure for a single 90 in3 airgun towed at a depth of 6 m is 

shown in Figure 120. The overpressure signature (Figure 120a) consist of a strong primary peak, related 

to the initial firing of the airguns, followed by a series of pulses associated with the bubble oscillations. 

Most energy is produced at frequencies below 600 Hz (Figure 121). Zero-to-peak SPL is 227.7 dB re 

1 μPa @ 1 m and source SEL is 207.8 dB re 1 μPa2 @ 1 m. 
Gulf of Mexico G&G Activities Programmatic EIS D-183

Maximum (horizontal) 1/3-octave-band source levels over all azimuths are shown in Figure 121. 

(a) (b) 

Figure 120. Predicted (a) overpressure signature and (b) power spectrum in the broadside and endfire 

(horizontal) directions for a single 90 in3

 airgun. 

Figure 121. Maximum 1/3-octave-band source level in the horizontal plane for a single 90 in3 airgun. The 

maximum over all modeled azimuths is shown for each 1/3-octave-band. 

7.3.1.2. Boomer

To estimate the broadband source level for the AA301 boomer (350 J input energy) from the source level 

for AP3000 system (1000 J input energy), we applied a −4.6 dB correction factor. The estimated source 

levels for the boomer plate—198.4 dB 1 μPa @ 1 m rms SPL and 168.0 dB re 1 μPa2

·s @ 1 m SEL—

were significantly lower than those provided by the manufacturer because the manufacturer’s level is 

estimated based only on the input energy. When electrical signals are converted into acoustic waves, 

output source levels are reduced. 

The power spectrum of the boomer signal and the beamwidth at different frequencies were estimated 

based on Simpkin’s (2005) study of the Huntec’70 Deep Tow Boomer, a typical boomer plate of 

comparable dimensions. The source level in each 1/3-octave-band was calculated based on the broadband 

source level and relative power spectrum data (Table 70).

The parameters of the AA301 boomer used for modeling were: 

• Operating frequency (wide band): 100 Hz–10 kHz

• Beam width: omnidirectional –11° 
D-184 Acoustic Propagation and Marine Mammal Exposure Modeling

• Beams: 1

• Beam direction: vertically down

• Maximum energy input (per shot): 350 J 

• rms SPL: 198.4 dB re 1 μPa @ 1 m TrmsSPL=0.2 ms (estimated from field measurements; Martin et al. 

2012) 

• Per pulse SEL: 171.0 dB re 1 μPa2·s @ 1 m (estimated from field measurements; Martin et al. 2012)

Table 70. Estimated source levels (SELs) and beamwidths from the AA301 boomer plate at 350 J per pulse 

distributed into twenty 1/3-octave-bands. 

1/3-octave-band 

center frequency (Hz)

Band SEL

(dB re 1 μPa2·s @ 1 m) Beam width

100 152.0 Omnidirectional

125 153.0 Omnidirectional

160 154.0 Omnidirectional

200 155.0 Omnidirectional

250 155.4 Omnidirectional

315 156.1 Omnidirectional

400 156.7 Omnidirectional

500 157.5 Omnidirectional

630 158.4 Omnidirectional

800 159.0 Omnidirectional

1,000 159.8 Omnidirectional

1,250 160.5 105°

1,600 160.6 78°

2,000 160.9 60°

2,500 160.4 47°

3,150 159.8 37°

4,000 159.1 29°

5,000 157.9 23°

6,300 156.8 18°

8,000 155.1 14°

10,000 151.8 11°

Broadband 171.0 Omnidirectional

We compared the boomer source with the 90 in3 airgun to confirm if acoustic field modeling results for 

the airgun were adequate to approximate the ones for the boomer. The broadband source levels for the 

airgun and the boomer were calculated after the set of M-weighted filters were applied (Table 71). As 

indicated in the Table 71, the broadband source level for the boomer is lower than for the airgun after 

application of all applicable M-weighting filters. Considering the negligible fraction of the surveys 

conducted using boomers and that the estimated impact from the 90 in3 is always greater than for the 

boomer, the 90 in3 airgun results were proposed as a conservative substitute for the boomer. Therefore, 

the source level modeling results presented in this section were not used in any acoustic field results or 

exposure estimates.
Gulf of Mexico G&G Activities Programmatic EIS D-185

Table 71. Boomer and 90 in3 airgun broadband source levels after M-weighting filters were applied.

Source FLAT Type I 

LFC

Type I 

MFC

Type I 

HFC

Type II 

MFC

Type II 

HFC

90 in3 207.8 206.0 190.7 188.6 174.3 169.2

Boomer 171.2 171.0 170.7 170.5 158.0 155.6

LFC=low-frequency cetaceans, MFC= mid-frequency cetaceans, HFC=high-frequency cetaceans

7.3.1.3. High-resolution Acoustic Sources

7.3.1.3.1. Multibeam Echosounder—Simrad EM2000

For the multibeam echosounder, the operational parameters producing the greatest acoustic impact were 

modeled. The Simrad EM2000 multibeam echosounder was modeled at the operational frequency of 

200 kHz, maximum source level of 203 dB re 1 μPa @ 1 m, the pulse length of 1.3 ms. The source beam 

pattern was modeled using rectangular transducer theory (Section 5.1.2.2). 

The estimated beam pattern from the transmitter of Simrad EM2000 is provided in Figure 122 as vertical 

slices along- and across-track directions. 

Figure 122. Vertical beam pattern calculated for the Simrad EM2000 multibeam 88° × 17° width in the 

(left) along- and (right) across-track directions.

7.3.1.3.2. Side-scan Sonar—EdgeTech 2200 IM

The side-scan sonar EdgeTech 2200 IM was modeled at two operational frequencies, 120 and 410 kHz. 

The rms SPL source level was estimated based on the peak source levels at 207 and 213 dB re 1 μPa @ 

1 m for 120 and 410 kHz center frequencies. The SEL source level was estimated based on the rms SPL 

source level values and the pulse lengths at 186.2 and 186.8 dB re 1 μPa2·s for 120 and 410 kHz center 

frequencies.

The source beam pattern was modeled using rectangular transducer theory (Section 5.1.2.2). The 

estimated beam pattern from the transmitter of the EdgeTech 2200 IM side-scan sonar is provided in 
D-186 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 123 as slices at 20° declination angle (through beam maximums) and vertical across-track 

directions. 

Figure 123. Vertical beam pattern calculated for the EdgeTech 2200 IM side-scan sonar 70° × 0.8° width 

and 20° declination angle. Slices (left) at 20° declination angle and (right) across-track 

directions. 

7.3.1.3.3. Sub-bottom Profiler—EdgeTech 2200 IM, DW−424

The chirp sub-bottom profiler emits a pulse, with a frequency constantly changing over time from the 

lower frequency of the working band at the beginning of the pulse to the higher frequency at the end of 

the pulse. The amplitude of the pulse also changes. Field measurements on a similar chirp system (Zykov 

and MacDonnell 2013) showed that the maximum amplitude of the pulse is achieved at the center 

frequency of the range, approximately. The pulse amplitude holds this maximum in the two 

1/3-octave-bands closest to the center frequency of the operational band and drops by about 10 dB for the 

1/3-octave-bands on either side of the maximum, dropping farther by 30 dB from the maximum at either 

end of the operational band. As a result, the chirp sub-bottom profiler can be modeled with sufficient 

accuracy using only the center frequency of the operational band. 

The chirp sub-bottom profiler of EdgeTech 2200 IM system was modeled at single frequency of 14 kHz. 

The rms SPL source level was considered at 200 dB re 1 μPa @ 1 m. The SEL source level was estimated 

based on the rms SPL source level and the pulse length at 180 dB re 1 μPa2·s. The beamwidth was 

estimated at 20° at the center frequency.

The source beam pattern was modeled using circular transducer beam theory (Section 5.1.2.1). The 

estimated beam pattern from the transmitter of the EdgeTech 2200 IM chirp sub-bottom profiler is 

provided in Figure 124 as a vertical slice. The beam is omnidirectional in the horizontal plain.
Gulf of Mexico G&G Activities Programmatic EIS D-187

Figure 124. Vertical beam pattern calculated for the EdgeTech 2200 IM sub-bottom with 20° beamwidth. 

7.3.2. Per-Pulse Acoustic Field 

7.3.2.1. Per-Pulse Acoustic Field for Input to JEMS

Acoustic propagation modeling was performed for of all sources at the modeling sites. The per-pulse 

acoustic fields were used as input for the exposure simulation using JEMS (Section 7.2.7). The acoustic 

fields were passed as 3-D cylindrical grids (range-depth-azimuth) of received levels.

7.3.2.1.1. Seismic Survey (8000 in3 Airgun Array) 

The acoustic field from 8000 in3 airgun array was modeled at 10 sites in each of the regions (East, 

Central, and West) for a total of 30 sites in the Gulf of Mexico (see Figure 110, Tables 48–51). At each 

site a towing azimuth of 0° or 90° was used based on the orientation of the survey box. Special 

consideration was given to the simulation of the Coil survey (Section 7.2.2.4) because of its continuously 

changing towing direction as the survey vessel follows a circular path. To accommodate the changing tow 

direction, additional acoustic fields were created using 9 different towing azimuths from 0° to 160° with a 

20° step. The towing directions from 180° to 340° were represented by the same fields assuming source 

geometry symmetry for the towing axis. Considering the directivity pattern of the array, it was assumed 

that 20° towing azimuth step was optimal for exposure modeling.

Transmission loss was modeled along 15 radial profiles (angular step 22.5°) to the range of up to 50 km 

from the source location. The horizontal step along the radials was 10 m. At each surface sampling 

location, the sound field was sampled at multiple depths:

• 2 m 

• Every 5 m from 5 to 20 m 

• Every 10 m from 20 to 100 m 

• Every 25 m from 100 to 200 m 

• Every 50 m from 200 to 300 m 
D-188 Acoustic Propagation and Marine Mammal Exposure Modeling

• Every 100 m from 300 to 1200 m 

• Every 200 m from 1200 to 3000 m 

The frequencies up to 5 kHz for the airgun array source were considered in the calculations of the 

broadband received levels. All 1/3-octave-band frequencies from 10 Hz to 5 kHz were used for the airgun 

array source level modeling (Section 7.3.1). For the transmission loss calculations, frequencies higher 

than 2 kHz were computationally intensive, so it was assumed that the transmission loss field for higher 

frequencies (up to 5 kHz) is identical to that at 2 kHz.

For each modeling scenario, the acoustic fields were calculated in SEL and rms SPL metrics. The rms 

SPL field was estimated from SEL field by applying range/depth/azimuth dependent conversion factor, 

which was obtained with full waveform modeling (Section 5.2.4). In addition to the unweighted acoustic 

fields, a set of filtered acoustic fields were calculated by applying M-weighting filters: Type I (low, 

medium, and high frequency) for rms SPL and Type II (medium and high frequency) for SEL. The total 

number of precomputed acoustic field grids prepared for the exposure simulation with JEMS was more 

than 1600. 

7.3.2.1.2. Geotechnical Surveys with High-resolution sources

The acoustic field from the high-resolution sources (90 in3 airgun, sub-bottom profiler, side-scan sonar, 

and multibeam sonar) was modeled at 7 sites: center of each survey box (see Figure 110 and Table 51). At 

each site, a towing azimuth of 0° or 90° was used based on the orientation of the survey box. 

The high-frequency geotechnical sources have significantly finer structure to the beam pattern in the 

horizontal plane compared to the large airgun array. The geometry of the profiles along which the 

acoustic propagation was modeled was individually adjusted for each source based on the beam pattern 

(Table 72).

At each surface sampling location along the modeled profiles, the sound field was sampled at multiple 

depths: 

• 2 m 

• Every 5 m from 5 to 20 m 

• Every 10 m from 20 to 100 m 

• Every 25 m from 100 to 200 m 

• Every 50 m from 200 to 300 m 

• Every 100 m from 300 to 1200 m 

• Every 200 m from 1200 to 3000 m 

For each modeling scenario, the acoustic fields were calculated in SEL and rms SPL metrics. The rms 

SPL field was estimated from SEL field by applying constant conversion factor of +10 dB (see 

Section 5.2.4). In addition to the unweighted acoustic fields, a set of filtered acoustic fields were created 

by applying M-weighting filters: Type I (low, medium, and high frequency) for rms SPL and Type II 

(medium and high frequency) for SEL.
Gulf of Mexico G&G Activities Programmatic EIS D-189

Table 72. Modeling parameters for the geotechnical sources.

Source Frequencies 

modeled Profiles Range modeled (km)

Grid size 

(m)

90 in3 airgun 10–2000 Hz 72 (5° angle step) 50 10

Multibeam 200 kHz 130 (3° angle step)

3 5 Side-scan sonar

120 kHz, 

410 kHz

236 (see Table 73 for 

angle steps)

Sub-bottom 

profiler 14 kHz 90 (4° angle step)

Table 73. Angle step configuration of profiles around side-scan sonar. In total, 236 profiles were modeled.

7.3.2.2. Range to Zero-to-Peak SPL Isopleths

To evaluate the risk of acoustic injury, the range to the unweighted, zero-to-peak SPL (dB re 1μPa) is 

needed for the 200 dB isopleth (high frequency cetaceans) and 230 dB isopleth (low and medium 

frequency cetaceans). The spherical spreading law:

)( LRL R)log(20 pk pkSL ⋅−= , 

where LpkSL is the peak SPL source level of the source and R is the range, was assumed as the propagation 

model for peak SPL. The ranges to the thresholds were calculated for each source (Table 74).

Horizontal range, in degrees, 

around source

Angle step, in degrees, 

for profiles

0–45 3 

45–75 2 

75–84 1 

84–88 0.4

88–92 0.2

92–96 0.4

96–105 1 

105–135 2 

135–225 3 

225−255 2 

255–264 1 

264–268 0.4

268–272 0.2

272–276 0.4

276–285 1 

285–315 2 

315–360 3 
D-190 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 74. Ranges to specific threshold levels for all sources.

Source Source level

(peak SPL; dB)

Range (m)

230 dB peak SPL 200 dB peak SPL

8000 in3 airgun array 255.2 18 575

90 in3 airgun array 227.7 – 24

Side-scan sonar 213 – 4.5

Sub-bottom profiler 203 – – 

Multibeam echosounder 206 – – 

7.3.2.3. Per-Pulse Acoustic Field for Threshold Ranges

The per-pulse acoustic fields were processed to provide two products: 

• Tables of ranges to specific thresholds from 210 dB down to 110 dB with a 10 dB step

• Maps of the acoustic field around the sources

The tables of threshold ranges can help to determine at what range from each source a potential exposure 

can occur. The maps provide the view of azimuthal variability of the received acoustic field. Appendix E

provides a sample of the tables of threshold ranges and maps for Site CM3 (Central-Slope zone, 750 m 

water depth). Appendix E provides results for all sources in Box 4 for Seasons 1 and 3 and in SEL and 

rms SPL metric. The threshold ranges were calculated for all applicable M-weighting filters.

7.3.3. 24-hour Exposure Estimates

Simulations were run in the 3MB survey areas (Section 7.2.5) and, using JEMS, were convolved with the 

per-pulse acoustic fields (Section 7.3.2). The result is the time history of acoustic exposure (received 

levels) for the animats in the simulation. There were many animats in the simulations and together their 

received levels represent the probability, or risk, of exposure for each survey. This can be seen by plotting 

the received levels as a histogram. Figure 125 shows the received-level SEL in a 24 h window for Kogia

species. The frequency of occurrence of the received levels is plotted as a function of the received level, 

so the histogram is a discretized representation of the exposure probability density function (PDF). PDFs 

are often normalized so that the area under the curve is equal to 1. That can be accomplished by dividing 

by the modeling animat density to get the probability of occurrence for the operation. It is the number of 

animals exposed to levels exceeding threshold that we are interested in, so the probability can be 

multiplied by the real-world density of animals in the simulation area. Therefore, the number of 

individual animals expected to exceed threshold is the number of animats exposed to levels exceeding 

threshold multiplied by the real-world animal density/model animat density. 
Gulf of Mexico G&G Activities Programmatic EIS D-191

Figure 125. Probability density function of received levels shown as a histogram. Cumulative SEL for 

Kogia species using short-finned pilot whales as the surrogate and high-frequency weighting 

in Box 3 for a 2-D survey. The SEL threshold for injury is 161 dB re 1 μPa2

·s. 91 animats 

exceeded the threshold in this 24 h window. 

Seven-day simulations were run and the number of animats exposed to levels exceeding threshold were 

determined in 24 h windows within the seven days. In a sliding-window approach, the first 24 h window 

begins at the start of the simulation and each subsequent window is advanced by 4 h. This gave 42 

samples for each survey, and the mean value was used as the 24 h estimate for that survey. The number of 

individuals exposed to levels exceeding the NMFS criteria, 180 and 160 dB rms SPL, respectively for 

injury and behavior, were found. Additional metrics were used to evaluate potential injury, cumulative 

SEL and zero-to-peak SPL. SEL was determined by summing acoustic energy received from each source 

integrated over 24 h. Range was used to determine the zero-to-peak SPL for each animat relative to each 

source. The number of animats within the range where the received level could exceed threshold were 

found. A graded function was also used as an additional metric to evaluate potential behavioral response. 

SEL used Type I weighting for low-frequency species (Bryde’s whales) and Type II weighting for the 

mid- and high-frequency species. Type I weighting was used for rms SPL sound fields with the graded 

function to evaluate potential behavioral response. The remaining metrics (NMFS criteria and zero-topeak SPL) were not weighted. 

The number of real-world individual animals expected to exceed the various thresholds were calculated 

using the 24-hour averaged exposure estimates for animats in each of the zones corresponding to our Gulf 

of Mexico modeling zones (Section 7.2.3). To get the real-world individual exposure estimates, the 

modeled exposure estimates were scaled by the ratio of the mean real-world density estimate from the 

zone to the modeled density. The mean real-world density estimates were obtained from the Marine 

Geospatial Ecology Laboratory (Duke University) model (Roberts et al. In preparation; Section 7.2.6, and 

Tables 62–68). The exposure estimates for real-world animals is then known for 24 hours of operations in 

each modeling zone, for each source, for each of the modelled seasons, and for each species. These values 

represent the number of real-world individual animals potentially exposed to levels exceeding the various 

threshold criteria instead of animats. By integrating these results with the predicted number of days of 

operations of each source type (see Table 75), Tables F-1 through F-81 provided the annual estimates for 

each source (for all modeled zones) for each of the modelled years.
D-192 Acoustic Propagation and Marine Mammal Exposure Modeling

7.3.4. Annual Exposure Estimates

The overall goal of this analysis was to estimate the number of exposures for each species for each year 

for the entire Gulf. Projections of survey level of effort for the different survey types for the Gulf

Planning Areas (Eastern, Central, and Western; divided into shallow and deep zones) were provided by 

BOEM (Table 75). Our modeling zones and survey locations were chosen, in part, to coincide with the 

Planning Areas so that the survey projections could be easily used for scaling. The shallow portion of the 

east, central, and western Planning Areas were the same as our modeling zones 1–3. A portion of each of 

the deep parts of Planning Areas maps directly to our modeling zones 4–6. The remainder of the deep 

parts of the Planning Areas were combined as modeling zone 7. The 24 h exposure estimates were scaled 

by the projected number of survey days to get the annual aggregate exposure estimates. The annual 

aggregate results are shown in Appendix F. Tables 76–82 show the sum of the annual results representing 

the 2016–2025 decade exposure estimates. The exposure estimates are the number of individual animals 

with the potential to exceed each of the criteria used to evaluate potential injury (SEL, peak SPL, and 180 

dB rms SPL) and potential behavioral disruption (the step function, and 160 dB rms SPL). The estimates 

are for each type of survey and for each marine mammal species. 

Table 75. Projected level of effort in days (24 h) for survey types in years 2016 to 2025. 2-D seismic survey is an 

8000 in3 airgun array with 1 vessel. 3-D seismic survey is an 8000 in3 airgun array with two vessels. The WAZ 

seismic survey is an 8000 in3 airgun array with four vessels. Coil seismic survey is an 8000 in3 airgun array with four 

vessels. Shallow hazards seismic survey is a 90 in3 airgun. The high resolution sources include for side-scan sonar, 

multibeam, and sub-bottom profiler. VSP is an 8000 in3 airgun array with one vessel.

Year Zone 2-D 3-D WAZ Coil Shallow hazards Boomer High resolution

sources

VSP

2016

1 0 0 0 0 0 0 1 0 

2 0 243 0 0 2 0 19 0 

3 0 30 0 0 0 0 4 0 

4 0 0 0 0 0 0 0 0 

5 56 389 192 82 0 0 26 2 

6 0 186 49 21 0 0 10 0 

7 69 515 248 106 0 0 34 2 

2017

1 0 0 0 0 0 0 1 0 

2 0 364 43 19 2 0 19 0 

3 0 0 0 0 0 0 4 0 

4 33 0 0 0 0 0 0 0 

5 0 389 192 82 0 0 26 2 

6 0 99 0 0 0 0 11 0 

7 30 502 241 103 0 0 34 2 

2018

1 0 0 0 0 0 0 1 0 

2 0 243 0 0 2 0 18 0 

3 0 0 0 0 0 0 4 0 

4 0 0 0 0 0 0 1 0 

5 0 342 160 69 0 0 27 2 

6 0 186 49 21 0 0 12 0 

7 0 456 208 89 0 0 36 2 
Gulf of Mexico G&G Activities Programmatic EIS D-193

Year Zone 2-D 3-D WAZ Coil Shallow hazards Boomer High resolution

sources

VSP

2019

1 0 0 0 0 0 0 0 0 

2 0 364 43 19 2 1 16 0 

3 0 30 0 0 0 0 3 0 

4 66 61 21 9 0 0 1 0 

5 28 247 96 41 0 0 27 2 

6 0 99 0 0 0 0 12 0 

7 94 380 140 60 0 0 36 2 

2020

1 0 0 0 0 0 0 0 0 

2 0 243 0 0 0 0 20 0 

3 0 0 0 0 0 0 3 0 

4 0 92 0 0 0 0 0 0 

5 0 295 192 82 2 1 25 2 

6 0 99 0 0 0 0 13 0 

7 0 467 241 103 3 2 34 3 

2021

1 0 0 0 0 0 0 0 0 

2 0 364 43 19 0 0 18 0 

3 0 0 0 0 0 0 2 0 

4 0 92 0 0 0 0 1 0 

5 0 247 160 69 0 0 30 2 

6 0 186 49 21 0 0 13 0 

7 0 421 208 89 0 0 40 3 

2022

1 0 0 0 0 0 0 0 0 

2 0 243 0 0 0 0 16 0 

3 0 30 0 0 0 0 2 0 

4 33 61 21 9 0 0 1 0 

5 28 247 160 69 0 0 32 2 

6 0 99 0 0 0 0 13 0 

7 64 380 220 94 0 0 43 3 

2023

1 0 0 0 0 0 0 0 0 

2 0 364 43 19 0 0 16 0 

3 0 0 0 0 0 0 2 0 

4 11 61 0 0 0 0 1 0 

5 9 247 128 55 0 0 35 2 

6 0 99 0 0 0 0 13 0 

7 21 380 160 69 0 0 46 3 

2024

1 0 0 0 0 0 0 0 0 

2 0 243 0 0 0 0 16 0 

3 0 0 0 0 0 0 2 0 

4 0 61 0 0 0 0 1 0 
D-194 Acoustic Propagation and Marine Mammal Exposure Modeling

Year Zone 2-D 3-D WAZ Coil Shallow hazards Boomer High resolution

sources

VSP

5 0 200 192 82 0 0 35 2 

6 0 99 0 0 0 0 14 0 

7 0 321 241 103 0 0 47 3 

2025

1 0 0 0 0 0 0 0 0 

2 0 364 43 19 0 0 13 0 

3 0 30 0 0 0 0 2 0 

4 5 61 0 0 0 0 1 0 

5 0 200 160 69 0 0 37 2 

6 0 99 0 0 0 0 14 0 

7 5 321 200 86 0 0 49 3 

Table 76. Decade exposure estimates totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 15.4 0.4 799.2 11119.4 25677.0

Beaked whales 8.6 0.2 817.5 63149.9 14473.3

Common bottlenose dolphins 38.3 2.7 1537.0 28167.1 62589.2

Bryde’s whales 0.1 1.6 10.6 170.7 206.9

Clymene dolphins 53.3 4.1 1323.7 24009.2 44719.5

False killer whales 11.4 0.3 357.1 5674.4 10068.6

Fraser’s dolphins 5.3 0.1 434.5 3293.6 5461.2

Killer whales 0.6 0.0 51.3 356.0 513.9

Kogia 695.3 54.8 562.3 4109.2 9529.1

Melon-headed whales 27.5 0.5 2042.3 16758.4 30165.0

Pantropical spotted dolphins 392.2 32.9 9484.5 147959.4 233759.0

Pygmy killer whales 8.8 0.2 271.9 4103.6 6791.7

Risso’s dolphins 14.4 1.6 386.5 6152.2 11897.9

Rough-toothed dolphins 14.1 0.5 445.9 7404.2 13861.5

Short-finned pilot whales 6.4 0.1 373.6 3756.0 7949.1

Sperm whales 5.3 0.5 1155.7 8440.7 17049.9

Spinner dolphins 37.5 2.4 975.3 22080.0 48754.6

Striped dolphins 24.4 2.0 600.2 10310.2 18203.5
Gulf of Mexico G&G Activities Programmatic EIS D-195

Table 77. Decade exposure estimates totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 3058.8 291.8 425998.1 1228034.9 1667456.2

Beaked whales 280.9 14.8 26069.3 1110419.9 278440.7

Common bottlenose dolphins 20841.3 987.6 2473207.9 6923848.5 8897488.1

Bryde’s whales 1.9 80.1 290.4 3445.4 4136.5

Clymene dolphins 2178.8 188.1 42251.2 511975.3 958233.2

False killer whales 608.9 63.7 14073.8 123229.2 222375.7

Fraser’s dolphins 287.4 20.1 11851.7 66174.0 110436.2

Killer whales 26.4 3.0 1464.6 6780.5 9922.1

Kogia 13737.4 3033.6 14719.0 76595.1 170808.1

Melon-headed whales 1378.5 103.4 54084.8 324416.8 577869.6

Pantropical spotted dolphins 12361.1 633.0 263990.9 2766953.3 4444346.7

Pygmy killer whales 449.7 43.4 9594.2 85023.0 147507.7

Risso’s dolphins 554.3 80.1 11917.9 124421.0 230226.7

Rough-toothed dolphins 899.8 96.1 34970.6 212341.8 367525.5

Short-finned pilot whales 372.7 47.3 13308.4 92144.7 188732.9

Sperm whales 209.8 9.9 39711.3 200875.5 440333.7

Spinner dolphins 1326.5 52.8 26421.5 379755.9 755780.9

Striped dolphins 864.9 57.0 17617.0 202165.4 356206.0
D-196 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 78. Decade exposure estimates totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 200.0 7.7 46492.0 176331.1 297393.7

Beaked whales 35.7 0.4 18840.3 509016.2 122280.5

Common bottlenose dolphins 731.6 23.9 214892.9 740252.6 1266979.2

Bryde’s whales 0.4 8.0 232.1 1537.8 1778.4

Clymene dolphins 382.2 9.9 24392.2 242870.1 423953.6

False killer whales 90.8 7.8 6945.0 52221.3 88802.1

Fraser’s dolphins 38.8 0.4 9055.6 30624.1 46756.5

Killer whales 3.8 0.6 984.1 3607.6 4493.7

Kogia 17564.6 328.7 11860.7 36823.3 78907.1

Melon-headed whales 192.9 1.9 42915.7 153249.3 254568.5

Pantropical spotted dolphins 2530.6 23.2 168480.7 1463671.7 2233856.1

Pygmy killer whales 70.6 6.8 5232.3 37762.1 60391.3

Risso’s dolphins 95.7 11.8 5304.4 61686.3 107841.1

Rough-toothed dolphins 114.8 8.7 9990.9 71087.6 124947.1

Short-finned pilot whales 45.2 1.3 8862.5 35979.0 71216.1

Sperm whales 70.2 0.5 31667.8 88325.5 182929.6

Spinner dolphins 268.6 0.7 17124.8 208893.6 410523.8

Striped dolphins 165.7 2.6 10805.2 102441.1 170483.2
Gulf of Mexico G&G Activities Programmatic EIS D-197

Table 79. Decade exposure estimates totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 289.2 9.1 13749.8 43206.0 61621.2

Beaked whales 99.3 4.0 5927.4 126419.5 25788.4

Common bottlenose dolphins 1408.5 72.1 53895.2 168113.4 206461.0

Bryde’s whales 0.7 28.1 55.8 339.3 365.1

Clymene dolphins 705.8 36.8 11518.1 60515.5 86456.1

False killer whales 172.4 7.0 4008.4 17015.2 26092.4

Fraser’s dolphins 78.7 1.8 2626.7 7884.0 9747.0

Killer whales 8.0 0.4 372.4 937.4 1085.9

Kogia 3430.4 925.4 3477.7 9621.9 16570.1

Melon-headed whales 380.8 9.2 12526.0 39889.1 53267.6

Pantropical spotted dolphins 5027.9 288.9 78535.6 363843.5 473365.5

Pygmy killer whales 130.8 5.0 3032.9 12322.3 18068.9

Risso’s dolphins 193.1 16.9 2913.9 15014.2 20920.1

Rough-toothed dolphins 220.8 9.5 5459.9 22950.9 35966.9

Short-finned pilot whales 81.3 2.3 2637.2 9621.6 14859.6

Sperm whales 65.3 5.5 8703.0 24374.2 40181.5

Spinner dolphins 473.7 21.0 8156.9 51218.3 81117.5

Striped dolphins 316.6 17.2 5071.9 25453.3 35226.2
D-198 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 80. Decade exposure estimates totals for 90 in3 airgun.

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 7.0 50.1 104.1

Beaked whales 0.0 0.0 0.0 34.8 1.8

Common bottlenose dolphins 0.0 0.0 57.7 228.8 353.6

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 1.0 2.9 3.4

False killer whales 0.0 0.0 0.2 0.9 1.4

Fraser’s dolphins 0.0 0.0 0.2 0.5 0.7

Killer whales 0.0 0.0 0.0 0.1 0.1

Kogia 0.1 0.0 0.3 0.5 0.9

Melon-headed whales 0.0 0.0 1.1 2.0 3.1

Pantropical spotted dolphins 0.0 0.0 6.1 20.0 25.3

Pygmy killer whales 0.0 0.0 0.2 0.5 0.7

Risso’s dolphins 0.0 0.0 0.2 0.7 1.1

Rough-toothed dolphins 0.0 0.0 0.5 4.6 7.7

Short-finned pilot whales 0.0 0.0 0.2 0.4 0.7

Sperm whales 0.0 0.0 0.4 2.1 4.6

Spinner dolphins 0.0 0.0 1.0 2.3 2.3

Striped dolphins 0.0 0.0 0.4 1.3 1.6
Gulf of Mexico G&G Activities Programmatic EIS D-199

Table 81. Decade exposure estimates totals for boomer.

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 1.3 7.5 15.0

Beaked whales 0.0 0.0 0.0 23.2 1.2

Common bottlenose dolphins 0.0 0.0 9.0 33.3 51.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.7 1.9 2.3

False killer whales 0.0 0.0 0.1 0.5 0.7

Fraser’s dolphins 0.0 0.0 0.2 0.3 0.4

Killer whales 0.0 0.0 0.0 0.0 0.1

Kogia 0.1 0.0 0.2 0.4 0.6

Melon-headed whales 0.0 0.0 0.7 1.3 2.0

Pantropical spotted dolphins 0.0 0.0 4.1 13.3 16.8

Pygmy killer whales 0.0 0.0 0.1 0.3 0.5

Risso’s dolphins 0.0 0.0 0.1 0.5 0.8

Rough-toothed dolphins 0.0 0.0 0.2 1.1 1.7

Short-finned pilot whales 0.0 0.0 0.1 0.3 0.4

Sperm whales 0.0 0.0 0.3 1.4 3.1

Spinner dolphins 0.0 0.0 0.6 1.5 1.5

Striped dolphins 0.0 0.0 0.3 0.9 1.0
D-200 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 82. Decade exposure estimate totals for the high resolution sources (side-scan sonar, sub-bottom profiler, and 

multibeam scanner).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 8.2 9.0 34.3 11.4

Beaked whales 0.0 0.7 0.7 45.6 0.0

Common bottlenose dolphins 0.0 95.2 122.8 245.3 68.5

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.1 0.1 0.1 0.0

False killer whales 0.0 0.0 0.0 0.1 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.1 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.1 0.1 0.1 0.0

Pantropical spotted dolphins 0.0 0.4 0.4 0.4 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.4 0.4 1.6 0.7

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.3 0.4 0.5 0.0

Spinner dolphins 0.0 0.1 0.1 0.1 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-201

8. Discussion 

This study provides estimates of annual marine mammal acoustic exposure due to geological and 

geophysical exploration activity in the Gulf of Mexico for years 2016 to 2025. Exposure estimates were 

computed from modeled sound levels received by simulated animals for several types of geophysical 

surveying. Because animals and sources move relative to the environment and each other, and the sound 

fields generated by the sources are shaped by various physical parameters, the sound levels received by an 

animal are a complex function of location and time. The basic modeling approach was to use acoustic 

models to compute the three-dimensional (3-D) sound fields and their variations in time. Simulated 

animals (animats) were modeled moving through these fields to sample the sound levels in a manner 

similar to how real animals would experience these sounds. From the time histories of the received sound 

levels of all animats, the numbers of animals exposed to levels exceeding effects threshold criteria were 

determined and then adjusted by the number of animals expected in the area, based on density 

information, to estimate the potential number of animals impacted.

In the preliminary Phase I component of this study (Section 6.3), a Test Case simulating a typical 3-D 

WAZ survey at two locations was performed to demonstrate and test the basic modeling approach and, 

importantly, to evaluate its limitations and accuracy of results prior to employing the methods in the main 

Phase II study (Section 7.2). A series of Test Scenarios were examined using, primarily, the results of the 

Test Case to investigate the effects of methodological choices on exposure estimates. With the overall 

modeling goal to estimate exposure levels from future survey activity whose individual details such as 

exact location and duration are unknown, a primary concern was how to scale results to account for 

different survey types, locations and spatial extents, and durations. 

In Test Scenario 1 (Section 6.5.1), issues arising when estimating impacts during long-duration surveys 

were investigated and a method was suggested. In this study, a 24 h reset period was used, meaning that 

received levels for all animats were reset to zero after any 24 h evaluation period. For time-based, SEL 

metrics, energy accumulation was restarted at zero after 24 h, and the time-independent SPL metrics 

maximum values were reset to zero. After each reset, animals were again available to be taken (counted 

as exposed above the effects threshold). A reset period creates a scaling time-basis for impact analysis, 

and 24 h is short relative to most surveys. It was shown in Test Scenario 1 that scaling (multiplying) the 

average 24 h exposure estimate by the number of days of survey was more conservative (produced lower 

number of animats exposed to levels exceeding threshold) than evaluating exposure for longer periods 

because individual animats could be counted multiple times. The parameters governing animal movement 

were obtained from short-duration events, such as several dives, and for this modeling project did not 

include long-duration behavior like migration or periodically revisiting an area as part of a circulation 

pattern. These behaviors could be modeled, but there are no data available currently to support detailed 

modeling of this type of behavior in the Gulf of Mexico. 

It was also found in Test Scenario 1 that the location-specific details of the survey had the greatest impact 

on exposure estimates—that is, whether the survey is conducted in shallow or deep water has a greater 

influence on exposure estimates than trends due to short-duration movement of the animats. Because 

specific location details for future surveys were not know, the modeling goal was to determine accurate 

24 h exposure estimates from representative surveys in the areas where future surveys may be conducted. 

The simulations should cover relevant acoustic environments, including areas with different sound 

velocity profiles, depths, and geoacoustic properties. Seven day simulations were chosen to ensure 

differing environments would be sampled. 

Sound velocity profiles change continuously, but it was shown in Test Scenario 2 (Section 6.5.2) that the 

primary difference in acoustic propagation due to changes in the sound velocity profile was the presence 

or absence of a sound conducting channel near the surface. In the Gulf, a surface duct only occurs in the 

winter season. To account for this difference in acoustic propagation, simulations were performed in 
D-202 Acoustic Propagation and Marine Mammal Exposure Modeling

winter and summer (with summer also representing spring and fall). The seven day simulations were 

analyzed in 24 h periods using a sliding window approach to get the average 24 h estimate for each 

survey type in each modeling zone. Future surveys of unknown duration may be conducted during any 

portion of the year and in any location within a specified Planning Area, so the aim of the modeling and 

analysis was to determine accurate 24 h exposure estimates to be scaled by the projected level of effort for 

the different survey types in order to provide yearly exposure estimates. 

With any modeling exercise, uncertainty in the input parameters results in uncertainty in the output. 

Sources of uncertainty and their effects on exposure estimates were investigated in Test Scenario 2. The 

primary source of uncertainty in this project was the location of the animals at the times of the surveys, 

which drives the choice of using an agent-based modeling approach and Monte Carlo sampling. 

Uncertainty in the density estimates of the animals is related to the uncertainty in the location of the 

animals. For the Phase II assessment we used density estimates from the Marine Geospatial Ecology 

Laboratory (Duke University) model (Roberts et al. In preparation) (Section 7.2.6.1). The model does not 

include seasonal variations of densities in the Gulf, and because surveys could occur at any location 

within a Planning Area, the density estimates were taken over an entire modeling zone. Similarly, the 

density was assumed to be uniform and static over the area covered by each survey. Real world animal

densities can fluctuate significantly, but assuming many surveys will be conducted in many locations the 

variations in density are expected to average toward the mean. Sources of uncertainty in the other 

modeling parameters were found to affect the variance of the modeling results, as opposed to their mean. 

Our common use of mean input parameters is therefore justified by the same argument as using mean 

animal densities. For example, the nominal pressure of an operating airgun array may be specified as 

2000 psi, but in practice the pressure will sometimes be higher or lower; therefore, the source level will be 

somewhat higher or lower. Again, over many surveys the average source level, and therefore received 

sound levels, will tend toward the specified nominal values. The effects of the variability in many of the 

modeling parameters on exposure estimates were quantified using a resampling technique (Bootstrap 

resampling). It was found that uncertainty in parameters such as animal density and social group size had 

a profound effect on the distribution of the exposure estimates, but not on the mean exposure. That is, the 

distribution shape and range of the number of animals above threshold changed, but the mean number of 

animals above threshold remained the same. Though a relatively minor effect, a small variability in the 

source level could increase the number of animals above threshold because the numbers of animals just 

below threshold is usually greater than the number of animats just above threshold. 

Some modeling options do affect the mean of the exposure estimates. Mitigation procedures, such as 

shutting down the airgun array when animals were detected within an established exclusion zone, could 

reduce the injury exposure estimates. Mitigation effectiveness, (Test Case 3, Section 6.5.3), was found to 

be influenced by several factors, such as the density of the animals in the survey area and detection 

probability. Some species are more easily detected than others, and detection probability varies with 

weather and observational set up. Weather during any seismic survey is unknown beforehand and 

detection probabilities are difficult to predict. As a conservative measure, the potential effects of 

mitigation were not included in the exposure estimates. 

Likewise, aversion, or animals avoiding loud or annoying sounds, could lead to reduced numbers of 

injury exposure estimates (Test Case 4, Section 6.5.4). Aversion is a behavioral response and depends on 

the context in which the sound is received and on biological factors, such as energetic and reproductive 

state, sociality, and health status of individual animals. Currently, too little is known about the factors that 

could influence aversion, including the thresholds for received sound levels that might elicit an aversion 

response, or movement of averting animals to justify decreasing the exposure estimates by assuming 

aversion. 

In summary, the choice of a 24 h resetting period separated the analysis of a survey into portions typically 

much shorter duration than the survey itself. The average 24 h exposure estimate scaled by the duration of 

the survey in days gives the exposure estimate for the total survey. There is variance associated with 24 h 
Gulf of Mexico G&G Activities Programmatic EIS D-203

exposure estimates due to sampling, movement of the survey, and uncertainty in modeling parameters. 

Variance, in general, affects the distribution shape of the number of animals above exposure criteria, but 

it did not significantly affect the mean number of animals above the criteria. When many surveys are 

pooled the effects of uncertainty are decreased. The aim of Phase II components of this study was to 

estimate the exposure distributions for each species, for each year, and over the entire gulf that result from 

many surveys. The resulting exposure estimates of Phase II represent the aggregate average exposure risk 

from future surveys given the specified levels of effort for each survey type in each year. 
D-204 Acoustic Propagation and Marine Mammal Exposure Modeling

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D-220 Acoustic Propagation and Marine Mammal Exposure Modeling

Appendix A. Per-Pulse Acoustic Field Example Radii Tables 

and Maps 

As with the per-pulse acoustic field input to ESME (Section 6.3.1.2), the per-pulse acoustic field for 

exclusion zone radii were computed for the Survey sites A and B modeling locations. Transmission loss 

was modeled along 72 radial profiles (angular step 5°) to the range of up to 130 km from the source 

location. The horizontal step along the radials was 10 m. At each surface sampling location, the sound 

field was sampled at multiple depths:

• 2 m 

• Every 5 m from 5 to 25 m 

• Every 25 m from 50 to 100 m 

• Every 50 m from 150 to 300 m 

• Every 100 m from 400 to 1200 m 

• Every 200 m from 1400 to 3000 m 

At each sampling range along the surface, the sound field was sampled at various depths. The received 

SEL at a surface sampling location was taken as the maximum value that occurs over all samples within 

the water column below, i.e., the maximum-over-depth received SEL. This provided a conservative 

prediction of the received sound level around the source, independent of depth. These maximum-overdepth per-pulse SELs were also converted to rms SPL estimates and are presented as color contours 

around the source in the shaded maps in Figures 126–128. For each sound level threshold, two statistical 

estimates of the safety radii are provided: (1) the maximum range (Rmax, in meters) and (2) the 95% range 

(R95%, in meters). Given a regularly gridded spatial distribution of sound levels, the R95% for a given sound 

level was defined as the radius of the circle, centered on the source, encompassing 95% of the grid points 

with sound levels at or above the given value. This definition is meaningful in terms of potential impact to 

animals because, regardless of the shape of the contour for a given sound level, R95% is the range from the 

source beyond which less than 5% of a uniformly distributed population would be exposed to sound at or 

above that level. The Rmax for a given sound level is simply the distance to the farthest occurrence of the 

threshold level (equivalent to R100%). It is more conservative than R95%, but may overestimate the effective 

exposure zone. For cases where the volume ensonified to a specific level is discontinuous and small 

pockets of higher received levels occur far beyond the main ensonified volume (e.g., due to convergence), 

Rmax would be much larger than R95% and could therefore be misleading if not given along with R95%. 

The per-pulse threshold radii for the 8000 in3 airgun array, with August sound speed profile, are presented 

at three modeling sites. Radii for the two Survey site A provinces, S01 and S02, are presented in Tables 

83 and 84; and for the Survey site B province, D01, in Table 85. The maps of maximum-over-depth 

sound pressure levels around the sources are also provided in Figures 126, 127, and 128, respectively.
Gulf of Mexico G&G Activities Programmatic EIS D-221

Table 83. 8000 in3 airgun array at the Survey site A, S01 modeling province: maximum (Rmax, m) and 95% (R95%, m) 

horizontal distance from the source to modeled broadband (10–5000 Hz) maximum-over-depth sound level 

thresholds, for August, without and with auditory frequency weighting applied for low-frequency cetaceans (LFC), 

mid-frequency cetaceans (MFC), and high-frequency cetaceans (HFC).

Type I M-Weighting

SEL 

(dB re 

1 μPa2·s)

SPLrms

(dB re 

1 μPa)

Un-weighted LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

200 210 40 40 40 32 10 10 < 10 < 10

190 200 150 130 140 120 50 50 30 30

180 190 500 410 480 390 150 132 120 110

170 180 1800 1460 1680 1370 510 455 390 351

160 170 4240 3680 4160 3580 1740 1560 1320 1160

150 160 10700 8690 10400 8580 5190 4470 4660 4160

140 150 34400 23700 31100 21400 14600 10300 11600 5240

130 140 > 130000 > 130000 > 130000 > 130000 57400 21100 21700 18600

120 130 > 130000 > 130000 > 130000 > 130000

Type II M-Weighting

SEL 

(dB re 1 μPa2·s)

SPLrms 

(dB re 1 μPa)

MFC HFC

Rmax R95% Rmax R95%

200 210 †

190 200 † < 10 < 10 < 10 < 10

180 190 † 20 20 10 10

170 180 † 70 61 40 40

160 170 † 250 230 130 120

150 160 † 780 700 420 380

140 150 † 3800 2520 1430 1250

130 140 † 5630 4860 4940 4310

120 130 † 19900 13600 11800 5360

110 120 † 107000 56400 21900 18900

100 110 † > 130000 > 130000 > 130000 > 130000

† rms levels computed by adding 10 dB to per-shot SEL levels.
D-222 Acoustic Propagation and Marine Mammal Exposure Modeling

Table 84. 8000 in3 airgun array at the Survey site A, S02 modeling province: maximum (Rmax, m) and 95% (R95%, m) 

horizontal distance from the source to modeled broadband (10–5000 Hz) maximum-over-depth sound level 

thresholds, for August, without and with auditory frequency weighting applied for low-frequency cetaceans (LFC), 

mid-frequency cetaceans (MFC), and high-frequency cetaceans (HFC).

Type I M-Weighting

SEL 

(dB re 

1 μPa2·s)

SPLrms

(dB re 

1 μPa)

Un-weighted LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

200 210 † 40 40 40 32 10 10 < 10 < 10

190 200 † 160 130 150 120 50 50 30 30

180 190 † 560 461 530 434 150 132 120 110

170 180 † 1580 1330 1540 1300 520 462 400 354

160 170 † 6490 4670 5770 4310 1870 1640 1690 1490

150 160 † 16500 12100 16500 11100 7370 6620 6950 4910

140 150 † 44500 32000 44400 29200 29600 16100 16700 15300

130 140 † 99300 80300 97900 75500 67000 49800 54500 40800

120 130 † > 100000 > 100000 > 100000 > 100000 > 100000 > 100000 > 100000 > 100000

† rms levels computed by adding 10 dB to per-shot SEL levels.

Type II M-Weighting

SEL 

(dB re 1 μPa2·s)

SPLrms 

(dB re 1 μPa)

MFC HFC

Rmax R95% Rmax R95%

200 210 † 

190 200 † < 10 < 10 < 10 < 10

180 190 † 20 20 10 10

170 180 † 70 61 40 40

160 170 † 250 230 130 120

150 160 † 810 711 430 381

140 150 † 3920 2080 1730 1530

130 140 † 15800 7010 7010 5380

120 130 † 41900 27800 17100 15600

110 120 † 80900 62100 54600 41800

100 110 † > 100000 > 100000 > 100000 > 100000
Gulf of Mexico G&G Activities Programmatic EIS D-223

Table 85. 8000 in3 airgun array at the Survey site B, D01 modeling province: maximum (Rmax, m) and 95% (R95%, 

m) horizontal distance from the source to modeled broadband (10–5000 Hz) maximum-over-depth sound level 

thresholds, for August, without and with auditory frequency weighting applied for low-frequency cetaceans (LFC), 

mid-frequency cetaceans (MFC), and high-frequency cetaceans (HFC).

Type I M-Weighting

SEL 

(dB re 

1 μPa2·s)

SPLrms 

(dB re 

1 μPa)

Un-weighted LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

200 210 † 40 40 40 32 10 10 < 10 < 10

190 200 † 150 130 140 120 50 50 30 30

180 190 † 500 404 470 383 150 132 120 110

170 180 † 1620 1310 1540 1240 510 454 390 352

160 170 † 5700 4270 5020 4070 1690 1500 1280 1120

150 160 † 19800 12700 14900 12700 6320 5620 4740 4140

140 150 † 47600 35100 43400 32100 15500 8970 9690 8810

130 140 † 101000 77300 100000 65900 20700 16800 18000 15600

120 130 † > 130000 > 130000 > 130000 > 130000 34900 24300 26300 22000

110 120 † 71100 50300 53600 38900

100 110 † > 130000 > 130000 128000 94300

† rms levels computed by adding 10 dB to per-shot SEL levels.

Type II M-Weighting

SEL 

(dB re 1 μPa2·s)

SPLrms 

(dB re 1 μPa)

MFC HFC

Rmax R95% Rmax R95%

200 210 †

190 200 † < 10 < 10 < 10 < 10

180 190 † 20 20 10 10

170 180 † 70 61 40 40

160 170 † 250 230 130 120

150 160 † 770 683 420 373

140 150 † 2680 2370 1380 1210

130 140 † 8760 7820 5190 4500

120 130 † 16800 9530 9750 8870

110 120 † 23800 20100 18300 15700

100 110 † 43800 32200 26400 22200

† rms levels computed by adding 10 dB to per-shot SEL levels.
D-224 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 126. Broadband (10–5000 Hz) maximum-over-depth sound pressure levels for 8000 in3 airgun 

array, in August at the Survey site A, S01 modeling province. Blue contours indicate water 

depth in meters.
Gulf of Mexico G&G Activities Programmatic EIS D-225

Figure 127. Broadband (10–5000 Hz) maximum-over-depth sound pressure levels for 8000 in3 airgun 

array, in August at the Survey site A, S02 modeling province. Blue contours indicate water depth 

in meters.
D-226 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure 128. Broadband (10–5000 Hz) maximum-over-depth sound pressure levels for 8000 in3 airgun 

array, in August at the Survey site B, D01 modeling province. Blue contours indicate water 

depth in meters.
Gulf of Mexico G&G Activities Programmatic EIS D-227

Appendix B. Test Case Simulation Received Levels 

Figure B-1 to Figure B-6 show the occurrence frequency of cumulative SEL for all of the animats in the 

simulations for the combined acoustic energy of the airgun arrays during the five day simulation, panel A 

is Survey site A and panel C is Survey site B. The occurrence frequency of the maximum rms SPLs that 

animats received during the thirty-day simulation are shown in panel B for Survey site A and panel D for 

Survey site B 

B.1. Bryde’s Whales

 

Figure B-1. Bryde’s whale exposure frequency for injury (5 day) and behavior (30 day) simulations. (A) 

cumulative sound exposure level (SEL) for Survey site A; (B) maximum root-mean-square 

(rms) sound pressure level (SPL) for Survey site A; (C) cumulative sound exposure level 

(SEL) for Survey site B; and (D) maximum root-mean-square (rms) sound pressure level 

(SPL) for Survey site B.
D-228 Acoustic Propagation and Marine Mammal Exposure Modeling

B.2. Cuvier’s Beaked Whales

Figure B-2. Cuvier’s beaked whale exposure frequency for injury (5 day) and behavior (30 day) 

simulations. (A) cumulative sound exposure level (SEL) for Survey site A; (B) maximum 

root-mean-square (rms) sound pressure level (SPL) for Survey site A; (C) cumulative sound 

exposure level (SEL) for Survey site B; and (D) maximum root-mean-square (rms) sound 

pressure level (SPL) for Survey site B.
Gulf of Mexico G&G Activities Programmatic EIS D-229

B.3. Common bottlenose Dolphins

Figure B-3. Common bottlenose dolphin exposure frequency for injury (5 day) and behavior (30 day) 

simulations. (A) cumulative sound exposure level (SEL) for Survey site A; (B) maximum 

root-mean-square (rms) sound pressure level (SPL) for Survey site A; (C) cumulative sound 

exposure level (SEL) for Survey site B; and (D) maximum root-mean-square (rms) sound 

pressure level (SPL) for Survey site B.
D-230 Acoustic Propagation and Marine Mammal Exposure Modeling

B.4. Short-Finned Pilot Whales 

Figure B-4. Short-finned pilot whale exposure frequency for injury (5 day) and behavior (30 day) 

simulations. (A) cumulative sound exposure level (SEL) for Survey site A; (B) maximum 

root-mean-square (rms) sound pressure level (SPL) for Survey site A; (C) cumulative sound 

exposure level (SEL) for Survey site B; and (D) maximum root-mean-square (rms) sound 

pressure level (SPL) for Survey site B.
Gulf of Mexico G&G Activities Programmatic EIS D-231

B.5. Sperm Whales

Figure B-5. Sperm whale exposure frequency for injury (5 day) and behavior (30 day) simulations. (A) 

cumulative sound exposure level (SEL) for Survey site A; (B) maximum root-mean-square 

(rms) sound pressure level (SPL) for Survey site A; (C) cumulative sound exposure level 

(SEL) for Survey site B; and (D) maximum root-mean-square (rms) sound pressure level 

(SPL) for Survey site B.
D-232 Acoustic Propagation and Marine Mammal Exposure Modeling

B.6. Dwarf Sperm Whales

Figure B-6. Dwarf sperm whale exposure frequency for injury (5 day) and behavior (30 day) simulations. 

(A) cumulative sound exposure level (SEL) for Survey site A; (B) maximum root-meansquare (rms) sound pressure level (SPL) for Survey site A; (C) cumulative sound exposure 

level (SEL) for Survey site B; and (D) maximum root-mean-square (rms) sound pressure 

level (SPL) for Survey site B.
Gulf of Mexico G&G Activities Programmatic EIS D-233

Appendix C. Marine Mammal Distribution in the Gulf of 

Mexico 

This appendix contains distribution maps for the marine mammal species likely to be affected by 

geological and geophysical exploration surveys. The distributions were obtained from the Marine 

Geospatial Ecology Laboratory (Duke University) model (Roberts et al. In preparation) as GIScompatible rasters of density estimates in 100 km2 areas. These animal distributions guided our selection 

of modeling zones, which were also patterned on BOEM’s planning areas, and to maintain acoustic 

uniformity throughout zones. The zone boundaries are shown as overlays in the figures. 

The minimum, maximum, and mean density values and standard deviations of the means were obtained 

for each species in each zone (Table 62–Table 68).

C.1. Atlantic Spotted Dolphins

Figure C-1. Atlantic spotted dolphin distribution in the Gulf of Mexico project area. Density estimates 

were obtained from the Marine Geospatial Ecology Laboratory (Duke University) model 

(Roberts et al. In preparation), black lines depict the boundaries of the modeling zones. 
D-234 Acoustic Propagation and Marine Mammal Exposure Modeling

C.2. Beaked Whales

Figure C-2. Beaked whale distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
Gulf of Mexico G&G Activities Programmatic EIS D-235

C.3. Common Bottlenose Dolphins

Figure C-3. Common bottlenose dolphin distribution in the Gulf of Mexico project area. Density 

estimates were obtained from the Marine Geospatial Ecology Laboratory (Duke University) 

model (Roberts et al. In preparation), black lines depict the boundaries of the modeling zones. 
D-236 Acoustic Propagation and Marine Mammal Exposure Modeling

C.4. Bryde’s Whales

Figure C-4. Bryde’s whale distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
Gulf of Mexico G&G Activities Programmatic EIS D-237

C.5. Clymene Dolphins

Figure C-5. Clymene dolphin distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
D-238 Acoustic Propagation and Marine Mammal Exposure Modeling

C.6. False Killer Whales

Figure C-6. False killer whale distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
Gulf of Mexico G&G Activities Programmatic EIS D-239

C.7. Fraser’s Dolphins

Figure C-7. Fraser’s dolphin distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
D-240 Acoustic Propagation and Marine Mammal Exposure Modeling

C.8. Killer Whales 

Figure C-8. Killer whale distribution in the Gulf of Mexico project area. Density estimates were obtained 

from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts et al. In 

preparation), black lines depict the boundaries of the modeling zones. 
Gulf of Mexico G&G Activities Programmatic EIS D-241

C.9. Kogia Species

Figure C-9. Kogia distribution in the Gulf of Mexico project area. Density estimates were obtained from 

the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts et al. In 

preparation), black lines depict the boundaries of the modeling zones. 
D-242 Acoustic Propagation and Marine Mammal Exposure Modeling

C.10. Melon-headed Whales

Figure C-10. Melon-headed whale distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
Gulf of Mexico G&G Activities Programmatic EIS D-243

C.11. Pantropical Spotted Dolphins

Figure C-11. Pantropical spotted dolphin distribution in the Gulf of Mexico project area. Density 

estimates were obtained from the Marine Geospatial Ecology Laboratory (Duke University) 

model (Roberts et al. In preparation), black lines depict the boundaries of the modeling zones. 
D-244 Acoustic Propagation and Marine Mammal Exposure Modeling

C.12. Pygmy Killer Whales

Figure C-12. Pygmy killer whale distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
Gulf of Mexico G&G Activities Programmatic EIS D-245

C.13. Risso’s Dolphins

Figure C-13. Risso’s dolphin distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
D-246 Acoustic Propagation and Marine Mammal Exposure Modeling

C.14. Rough-toothed Dolphins

Figure C-14. Rough-toothed dolphin distribution in the Gulf of Mexico project area. Density estimates 

were obtained from the Marine Geospatial Ecology Laboratory (Duke University) model 

(Roberts et al. In preparation), black lines depict the boundaries of the modeling zones. 
Gulf of Mexico G&G Activities Programmatic EIS D-247

C.15. Short-finned Pilot Whales

Figure C-15. Short-finned pilot whale distribution in the Gulf of Mexico project area. Density estimates 

were obtained from the Marine Geospatial Ecology Laboratory (Duke University) model 

(Roberts et al. In preparation), black lines depict the boundaries of the modeling zones. 
D-248 Acoustic Propagation and Marine Mammal Exposure Modeling

C.16. Sperm Whales

Figure C-16. Sperm whale distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
Gulf of Mexico G&G Activities Programmatic EIS D-249

C.17. Spinner Dolphins

Figure C-17. Spinner dolphin distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
D-250 Acoustic Propagation and Marine Mammal Exposure Modeling

C.18. Striped Dolphins

Figure C-18. Striped dolphin distribution in the Gulf of Mexico project area. Density estimates were 

obtained from the Marine Geospatial Ecology Laboratory (Duke University) model (Roberts 

et al. In preparation), black lines depict the boundaries of the modeling zones. 
Gulf of Mexico G&G Activities Programmatic EIS D-251

Appendix D. 3MB Animal Movement Parameters 

The marine mammal movement and behavior (3MB) model uses previously measured animal movements 

to forecast how animals move in new situations and locations. 3MB creates simulated animals, referred to 

as animats, which are used to populate a simulation area. The animats are receivers; the sound levels they 

receive are logged as they move through the simulation. 

3MB controls animat movement in horizontal and vertical directions using sub-models (see Houser and 

Cross 2014). Travel sub-models determine horizontal movement, including sub-models for the animats’ 

travel direction and the travel rate (speed of horizontal movement). Dive sub-models determine vertical 

movement. Diving behavior sub-models include ascent and descent rates, maximum dive depth, bottom 

following, reversals, and surface interval. Bottom following describes the animat’s behavior when it 

reaches the seafloor, for example during a foraging dive. If the bottom-following option is selected, the 

animat will continue along the same bathymetric contour line instead of the horizontal direction 

determined by another sub-model. Reversals simulate foraging behavior by defining the number of 

vertical excursions the animat makes after it reaches its maximum dive depth. The surface interval is the 

amount of time an animat spends at the surface before diving again.

Species-specific, realistic movement is simulated by supplying the sub-models with appropriate input 

parameters for each species. Parameter values are determined by visually observing species and reviewing 

tagging studies. For most sub-models, the input parameter is a probability distribution. When detailed 

information about a species’ movements and behaviors are available, a user-created distribution vector 

should be used. When there is little to no information, either Gaussian or uniform distributions are used in 

the model. The user determines the appropriate mean and standard deviation for Gaussian distribution or 

the range if uniform distributions are being used. For behaviors with no directional preference, such as, 

perhaps, feeding and playing, a random walk model is used to define the bearing of an animats’ travel 

direction. In a random walk model, at each parameter transition time step all bearings are equally likely 

choices. A variation of the random walk model, the correlated random walk, includes a directional bias. 

This variant should be used when animals have a preferred absolute direction, such as migration. The 

correlated random walk option smooths the changes in bearing by using the current bearing as the mean 

of the distribution from which the next heading is selected. Another option to control travel direction 

allows the user to create a vector of directional probabilities. In addition to the input distribution, 

parameters have a termination function that governs how long the parameter persists in a simulation. 

Houser (2006) and Houser and Cross (2014) discuss these input parameters in more detail. 

3MB allows a user to define multiple behavioral states, which distinguish between specific subsets of 

behaviors like shallow and deep dives, or more general behavioral states such as foraging, resting, and 

socializing. The transition probability between these states can be defined as a probability value and 

related to the time of day. The level of detail included depends on the amount of data available for the 

species, and on the temporal and spatial framework of the simulation. 

The animal movement parameters developed for each species are in the following sections. There is little 

or no data available for some species included in this study. In these cases we used a surrogate, which 

reflects values for a similar species: Pantropical spotted dolphins were used as a surrogate for Clymene, 

spinner, and striped dolphins; short-finned pilot whales were a surrogate for Fraser’s dolphin, the Kogia

species, and melon-headed whales; and rough-toothed dolphin as the surrogate for false killer whales and 

pygmy killer whales. Table D-19 lists the groups used for animal movement modeling. 
D-252 Acoustic Propagation and Marine Mammal Exposure Modeling

D.1. Atlantic Spotted Dolphins

Table D-1. Distribution data for Atlantic spotted dolphins. Unless otherwise indicated, numbers in the Value column 

represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Random Max: 5.69, Min: 0.08) Davis et al. 1996

Ascent rate (m/s) Gaussian 1.15 (0.8) Griffin et al. 2005

Descent rate (m/s) Gaussian 1.23 (0.48) Griffin et al. 2005

Average depth (m) Random Max: 60 Davis et al. 1996

Bottom following Yes Griffin et al. 2005

Reversals Gaussian Best estimate

Probability of reversal 0.5 Best estimate

Number of reversals 2 (2) Griffin et al. 2005

Time in reversal log (s) 20.81 (21.5) Griffin et al. 2005

Surface interval (s) Gaussian 63.59 (52.66) Griffin et al. 2005
Gulf of Mexico G&G Activities Programmatic EIS D-253

D.2. Beaked Whale spp.

This category includes Cuvier’s, Blainville’s, and Gervais’ whales. Diving behavior for Blainville’s and 

Cuvier’s beaked whales (Baird et al. 2006b) is similar to the diving behavior documented for northern 

common bottlenose whales (Hooker and Baird 1999). 

Table D-2. Distribution data for beaked whale spp. are based on Cuvier’s beaked whale data. Unless otherwise 

indicated, numbers in the Value column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Deep dive Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.508 (0.392) Schorr et al. 2009

Ascent rate (m/s) Gaussian 0.7 (0.2) Baird et al. 2006b, Tyack et al. 2006

Descent rate (m/s) Gaussian 1.39 (0.19) Baird et al. 2006b, Tyack et al. 2006

Average depth (m) Gaussian 1070 (317) Tyack et al. 2006

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Best estimate

Number of reversals 5 (3) Baird et al. 2006a 

Time in reversal log (s) 696 (228) Baird et al. 2006a

Surface interval (s) Gaussian 486 (1035) Baird et al. 2006b

Bout duration (s) 3480 (684) Best estimate

Shallow dive Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.508 (0.392) Schorr et al. 2009

Ascent rate (m/s) Gaussian 0.66 (0.2) Baird et al. 2006b, Tyack et al. 2006

Descent rate (m/s) Gaussian 0.7 (0.46) Baird et al. 2006b, Tyack et al. 2006

Average depth (m) Gaussian 221 (100) Tyack et al. 2006

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Best estimate

Number of reversals 3 (2) Baird et al. 2006a

Time in reversal log (s) 304 (156) Baird et al. 2006a

Surface interval (s) Gaussian 486 (1035) Baird et al. 2006b

Bout duration (s) 912 (312) Best estimate
D-254 Acoustic Propagation and Marine Mammal Exposure Modeling

D.3. Common Bottlenose Dolphins

Table D-3. Distribution data for common bottlenose dolphins. Unless otherwise indicated, numbers in the Value 

column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Foraging Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.19 (0.71) Bearzi 2005

Ascent rate (m/s) Gaussian 2.1 (0.3) Houser et al. 2010

Descent rate (m/s) Gaussian 1.6 (0.2) Houser et al. 2010

Average depth (m) Gaussian 25 (5) Hastie et al. 2006

Bottom following Yes Best estimate

Reversals Gaussian 18 (1.1) Best estimate

Probability of reversal 0.09 Best estimate

Reversal dive rate Gaussian 1.0 (0.2) Best estimate

Time in reversal (s) Gaussian 1 (0.1) Best estimate

Surface interval (s) Gaussian 46.4 (2.5) Lopez 2009

Playing Travel Direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.19 (0.71) Bearzi 2005

Ascent rate (m/s) Gaussian 2.1 (0.3) Houser et al. 2010

Descent rate (m/s) Gaussian 1.6 (0.2) Houser et al. 2010

Average depth (m) Gaussian 7 (3) Wursig and Wursing 1979, Hastie et al. 

2006

Bottom following Yes Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 3 (2) Best estimate

Resting Travel Direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.19 (0.71) Bearzi 2005

Ascent rate (m/s) Gaussian 0.5 (0.1) Best estimate

Descent rate (m/s) Gaussian 0.5 (0.1) Best estimate

Average depth (m) Random Max: 2 Best estimate

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 3 (2) Best estimate

Socializing Travel Direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.19 (0.71) Bearzi 2005

Ascent rate (m/s) Gaussian 2.1 (0.3) Houser et al. 2010

Descent rate (m/s) Gaussian 1.6 (0.2) Houser et al. 2010
Gulf of Mexico G&G Activities Programmatic EIS D-255

Behavior Variable Value Reference

Average depth (m) Random Max: 10 Wursig and Wursing 1979, Hastie et al. 

2006

Bottom following Yes Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 3 (2) Best estimate

Travel Travel Direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.19 (0.71) Bearzi 2005

Ascent rate (m/s) Gaussian 2.1 (0.3) Houser et al. 2010

Descent rate (m/s) Gaussian 1.6 (0.2) Houser et al. 2010

Average depth (m) Gaussian 7 (3) Wursig and Wursing 1979, Hastie et al. 

2006

Bottom following Yes Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 3 (2) Best estimate
D-256 Acoustic Propagation and Marine Mammal Exposure Modeling

D.4. Bryde’s Whales 

Table D-4. Distribution data for Bryde’s whales. Unless otherwise indicated, numbers in the Value column represent 

means with their standard deviations in brackets after.

Behavior Variable Value Reference

Dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.39 (0.83) Kato and Perrin 2009

Ascent rate (m/s) Gaussian 0.95 (0.55) Alves et al. 2010

Descent rate (m/s) Gaussian 1.25 (0.4) Alves et al. 2010

Average depth (m) Random Max: 292 Alves et al. 2010

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Best estimate

Number of reversals 4 (3) Alves et al. 2010

Time in reversal log (s) 72 (21.2) Alves et al. 2010

Surface interval (s) Gaussian 188 (48) Di Sciara 1983

Bout duration (s) 288 (63.6) Best estimate
Gulf of Mexico G&G Activities Programmatic EIS D-257

D.5. Clymene Dolphins

Table D-5. Distribution data for Clymene dolphins based on Pantropical spotted dolphin data. Unless otherwise 

indicated, numbers in the Value column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Day dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 2.39 (1.22) Pantropical spotted dolphins

Ascent rate (m/s) Gaussian 0.42 (0.24) Pantropical spotted dolphins

Descent rate (m/s) Gaussian 0.58 (0.34) Pantropical spotted dolphins

Average depth (m) Gaussian 22.1 (15.71) Pantropical spotted dolphins

Bottom following No Pantropical spotted dolphins

Reversals No Pantropical spotted dolphins

Surface interval (s) Gaussian 59.4 (293.4) Pantropical spotted dolphins

Night dive Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.83 (1.54) Pantropical spotted dolphins

Ascent rate (m/s) Gaussian 0.74 (0.41) Pantropical spotted dolphins

Descent rate (m/s) Gaussian 0.93 (0.54) Pantropical spotted dolphins

Average depth (m) Gaussian 24 (27.1) Pantropical spotted dolphins

Bottom following No Pantropical spotted dolphins

Reversals Gaussian Pantropical spotted dolphins

Probability of reversal 0.5 Pantropical spotted dolphins

Number of reversals 3 (1) Pantropical spotted dolphins

Time in reversal log (s) 39 (55.2) Pantropical spotted dolphins

Surface interval (s) Gaussian 47.4 (106.8) Pantropical spotted dolphins
D-258 Acoustic Propagation and Marine Mammal Exposure Modeling

D.6. False Killer Whales

Table D-6. Distribution data for false killer whales. Unless otherwise indicated, numbers in the Value column 

represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Day dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Random Min: 1.18; Max: 1.59 Baird et al. 2010

Ascent rate (m/s) Gaussian 0.77 (0.61) Minamikawa et al. 2013

Descent rate (m/s) Gaussian 0.74 (0.72) Minamikawa et al. 2013

Average depth (m) Gaussian 63.3 (131.5) Minamikawa et al. 2013

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Minamikawa et al. 2013

Number of reversals 2 (1) Minamikawa et al. 2013

Time in reversal log (s) 65.76 (73.84) Minamikawa et al. 2013

Surface interval (s) Gaussian 569.69 (630.68) Minamikawa et al. 2013

Night dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Random Min: 1.18; Max: 1.59 Baird et al. 2010

Ascent rate (m/s) Gaussian 0.51 (0.42) Minamikawa et al. 2013

Descent rate (m/s) Gaussian 0.43 (0.4) Minamikawa et al. 2013

Average depth (m) Gaussian 26.4 (46.5) Minamikawa et al. 2013

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Minamikawa et al. 2013

Number of reversals 2 (1) Minamikawa et al. 2013

Time in reversal log (s) 127.68 (63.84) Minamikawa et al. 2013

Surface interval (s) Gaussian 299.4 (345.98) Minamikawa et al. 2013
Gulf of Mexico G&G Activities Programmatic EIS D-259

D.7. Fraser’s Dolphins 

Table D-7. Distribution data for Fraser’s dolphins based on Short-finned pilot whale data. Unless otherwise 

indicated, numbers in the Value column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Day dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.875 (0.572) Short-finned pilot whales

Ascent rate (m/s) Gaussian 2.2 (0.2) Short-finned pilot whales

Descent rate (m/s) Gaussian 2 (0.2) Short-finned pilot whales

Average depth (m) Gaussian 30 (20) Short-finned pilot whales

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 165 (69) Short-finned pilot whales

Night dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.875 (0.572) Short-finned pilot whales

Ascent rate (m/s) Gaussian 3.2 (0.4) Short-finned pilot whales

Descent rate (m/s) Gaussian 3 (0.4) Short-finned pilot whales

Average depth (m) Gaussian 300 (100) Short-finned pilot whales

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 165 (69) Short-finned pilot whales
D-260 Acoustic Propagation and Marine Mammal Exposure Modeling

D.8. Killer Whales 

Table D-8. Distribution data for killer whales. Unless otherwise indicated, numbers in the Value column represent 

means with their standard deviations in brackets after.

Behavior Variable Value Reference

Shallow dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 2 (1.61) Dahlheim and White 2010

Ascent rate (m/s) Gaussian 1.832 (1.448) Baird 1994

Descent rate (m/s) Gaussian 1.822 (1.51) Baird 1994

Average depth (m) Gaussian 8 (2) Miller et al. 2010

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 3 (2) Miller et al. 2010

Deep dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 2 (1.61) Dahlheim and White 2010

Ascent rate (m/s) Gaussian 1.832 (1.448) Baird 1994

Descent rate (m/s) Gaussian 1.822 (1.51) Baird 1994

Average depth (m) Gaussian 40 (20) Miller et al. 2010

Bottom following No Best estimate

Reversals Random Best estimate

Probability of reversal 1 Best estimate

Number of reversals Min: 2, Max: 5 Best estimate

Time in reversal log (s) 10 (1) Best estimate

Surface interval (s) Gaussian 3 (2) Miller et al. 2010
Gulf of Mexico G&G Activities Programmatic EIS D-261

D.9. Kogia spp. including Dwarf Sperm Whales and Pygmy Sperm 

Whales (Kogia sima and K. breviceps) 

Table D-9. Distribution data for Kogia spp. based on short-finned pilot whale data. Unless otherwise indicated, 

numbers in the Value column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Day dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.875 (0.572) Short-finned pilot whales

Ascent rate (m/s) Gaussian 2.2 (0.2) Short-finned pilot whales

Descent rate (m/s) Gaussian 2 (0.2) Short-finned pilot whales

Average depth (m) Gaussian 30 (20) Short-finned pilot whales

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 165 (69) Short-finned pilot whales

Night dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.875 (0.572) Short-finned pilot whales

Ascent rate (m/s) Gaussian 3.2 (0.4) Short-finned pilot whales

Descent rate (m/s) Gaussian 3 (0.4) Short-finned pilot whales

Average depth (m) Gaussian 300 (100) Short-finned pilot whales

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 165 (69) Short-finned pilot whales
D-262 Acoustic Propagation and Marine Mammal Exposure Modeling

D.10. Melon-headed Whales

Table D-10. Distribution data for melon-headed whales based on short-finned pilot whale data. Unless otherwise 

indicated, numbers in the Value column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Day dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.875 (0.572) Short-finned pilot whales

Ascent rate (m/s) Gaussian 2.2 (0.2) Short-finned pilot whales

Descent rate (m/s) Gaussian 2 (0.2) Short-finned pilot whales

Average depth (m) Gaussian 30 (20) Short-finned pilot whales

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 165 (69) Short-finned pilot whales

Night dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.875 (0.572) Short-finned pilot whales

Ascent rate (m/s) Gaussian 3.2 (0.4) Short-finned pilot whales

Descent rate (m/s) Gaussian 3 (0.4) Short-finned pilot whales

Average depth (m) Gaussian 300 (100) Short-finned pilot whales

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 165 (69) Short-finned pilot whales
Gulf of Mexico G&G Activities Programmatic EIS D-263

D.11. Pantropical Spotted Dolphins

Table D-11. Distribution data for pantropical spotted dolphins. Unless otherwise indicated, numbers in the Value 

column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Day dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 2.39 (1.22) Scott and Chivers 2009

Ascent rate (m/s) Gaussian 0.42 (0.24) Scott and Chivers 2009

Descent rate (m/s) Gaussian 0.58 (0.34) Scott and Chivers 2009

Average depth (m) Gaussian 22.1 (15.71) Scott and Chivers 2009

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 59.4 (293.4) Scott and Chivers 2009

Night dive Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.83 (1.54) Scott and Chivers 2009

Ascent rate (m/s) Gaussian 0.74 (0.41) Scott and Chivers 2009

Descent rate (m/s) Gaussian 0.93 (0.54) Scott and Chivers 2009

Average depth (m) Gaussian 24 (27.1) Scott and Chivers 2009

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Best estimate

Number of reversals 3 (1) Best estimate

Time in reversal log (s) 39 (55.2) Best estimate

Surface interval (s) Gaussian 47.4 (106.8) Scott and Chivers 2009
D-264 Acoustic Propagation and Marine Mammal Exposure Modeling

D.12. Pygmy Killer Whales

Table D-12. Distribution data for pygmy killer whales based on pantropical spotted and rough-toothed dolphin data.

Unless otherwise indicated, numbers in the Value column represent means with their standard deviations in brackets 

after.

Behavior Variable Value Reference

Travel dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.805 (0.05) Baird et al. 2011

Ascent rate (m/s) Gaussian 0.42 (0.24) Pantropical spotted dolphins

Descent rate (m/s) Gaussian 0.58 (0.34) Pantropical spotted dolphins

Average depth (m) Gaussian 6 (4) Rough-toothed dolphins

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 59.4 (293.4) Pantropical spotted dolphins

Forage dive Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.805 (0.05) Baird et al. 2011

Ascent rate (m/s) Gaussian 0.74 (0.41) Pantropical spotted dolphins

Descent rate (m/s) Gaussian 0.93 (0.54) Pantropical spotted dolphins

Average depth (m) Gaussian 25 (20) Rough-toothed dolphins

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Best estimate

Number of reversals 3 (1) Best estimate

Time in reversal log (s) 23.3 (50) Rough-toothed dolphins

Surface interval (s) Gaussian 47.4 (106.8) Pantropical spotted dolphins
Gulf of Mexico G&G Activities Programmatic EIS D-265

D.13. Risso’s Dolphins

Table D-13. Distribution data for Risso’s dolphins based on short-finned pilot whale data. Unless otherwise 

indicated, numbers in the Value column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.997 (1.058) Wells et al. 2009

Ascent rate (m/s) Gaussian 2.2 (0.2) Short-finned pilot whales

Descent rate (m/s) Gaussian 2 (0.2) Short-finned pilot whales

Average depth (m) Gaussian 11 (10) Wells et al. 2009

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 11 (4) Bearzi et al. 2011
D-266 Acoustic Propagation and Marine Mammal Exposure Modeling

D.14. Rough-toothed Dolphins

Table D-14. Distribution data for rough-toothed dolphins based on pantropical spotted dolphin data. Unless 

otherwise indicated, numbers in the Value column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Travel dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.25 (0.5) Ritter 2002

Ascent rate (m/s) Gaussian 0.42 (0.24) Pantropical spotted dolphins

Descent rate (m/s) Gaussian 0.58 (0.34) Pantropical spotted dolphins

Average depth (m) Gaussian 6 (4) Wells et al. 2008

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 59.4 (293.4) Pantropical spotted dolphins

Forage dive Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 2 (0.8) Wells et al. 2008

Ascent rate (m/s) Gaussian 0.74 (0.41) Pantropical spotted dolphins

Descent rate (m/s) Gaussian 0.93 (0.54) Pantropical spotted dolphins

Average depth (m) Gaussian 25 (20) Best estimate

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Best estimate

Number of reversals 3 (1) Best estimate

Time in reversal log (s) 23.3 (50) Norris et al. 1965

Surface interval (s) Gaussian 47.4 (106.8) Pantropical spotted dolphins
Gulf of Mexico G&G Activities Programmatic EIS D-267

D.15. Short-finned Pilot Whales

Table D-15. Distribution data for short-finned pilot whales. Unless otherwise indicated, numbers in the Value 

column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Day dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.875 (0.572) Wells et al. 2013

Ascent rate (m/s) Gaussian 2.2 (0.2) Aguilar Soto et al. 2009

Descent rate (m/s) Gaussian 2 (0.2) Aguilar Soto et al. 2009

Average depth (m) Gaussian 30 (20) Wells et al. 2013

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 165 (69) Sakai et al. 2011

Night dive Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.875 (0.572) Wells et al. 2013

Ascent rate (m/s) Gaussian 3.2 (0.4) Aguilar Soto et al. 2009

Descent rate (m/s) Gaussian 3 (0.4) Aguilar Soto et al. 2009

Average depth (m) Gaussian 300 (100) Wells et al. 2013

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 165 (69) Best estimate
D-268 Acoustic Propagation and Marine Mammal Exposure Modeling

D.16. Sperm Whales

Table D-16. Distribution data for sperm whales. Unless otherwise indicated, numbers in the Value column represent 

means with their standard deviations in brackets after.

Behavior Variable Value Reference

Deep foraging 

dive

Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.88 (0.27) Miller et al. 2004

Ascent rate (m/s) Gaussian 1.3 (0.2) Watwood et al. 2006

Descent rate (m/s) Gaussian 1.1 (0.2) Watwood et al. 2006

Average depth (m) Gaussian 546.9 (130) Watwood et al. 2006

Bottom following No Best estimate

Reversals Gaussian 8.2 (4.2) Aoki et al. 2007

Reversal dive rate (m/s) Gaussian 1.8 (0.5) Aoki et al. 2007

Time in reversal (s) Gaussian 141 (82.7) Amano and Yoshioka 2003, Aoki et al. 

2007

Surface interval (s) Gaussian 486 (156) Watwood et al. 2006

Inactive bottom 

time

Travel Direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.88 (0.27) Miller et al. 2004

Ascent rate (m/s) Gaussian 1.13 (0.07) Amano and Yoshioka 2003

Descent rate (m/s) Gaussian 1.4 (0.13) Amano and Yoshioka 2003

Average depth (m) Gaussian 490 (74.6) Amano and Yoshioka 2003

Bottom following No Best estimate

Reversals Gaussian 1.0 (0) Best estimate

Reversal dive rate (m/s) Gaussian 0.1 (0.1) Best estimate

Time in reversal (s) Gaussian 1188 (174.6) Amano and Yoshioka 2003

Surface interval (s) Gaussian 546 (354) Amano and Yoshioka 2003

V dive Travel Direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.88 (0.27) Miller et al. 2004

Ascent rate (m/s) Gaussian 0.67 (0.43) Amano and Yoshioka 2003

Descent rate (m/s) Gaussian 0.85 (0.05) Amano and Yoshioka 2003

Average depth (m) Gaussian 282.7 (69.9) Amano and Yoshioka 2003

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 408 (114) Amano and Yoshioka 2003
Gulf of Mexico G&G Activities Programmatic EIS D-269

Behavior Variable Value Reference

Surface inactive 

(head down) 

Travel Direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.0 (0.0) Best estimate

Ascent rate (m/s) Gaussian 0.1 (0.1) Miller et al. 2008

Descent rate (m/s) Gaussian 0.1 (0.1) Miller et al. 2008

Average depth (m) Gaussian 16.5 (4.9) Miller et al. 2008

Bottom following No Best estimate

Reversals Gaussian 1.0 (0) Best estimate

Reversal dive rate (m/s) Gaussian 0.0 (0.0) Best estimate

Time in reversal (s) Gaussian 804 (522) Miller et al. 2008

Surface interval (s) Gaussian 462 (360) Miller et al. 2008

Bout duration* T50 = 8.1, K = 0.9 Best estimate

Surface inactive 

(head up)

Travel Direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.0 (0.0) Best estimate

Ascent rate (m/s) Gaussian 0.1 (0.1) Miller et al. 2008

Descent rate (m/s) Gaussian 0.1 (0.1) Miller et al. 2008

Average depth (m) Gaussian 8.6 (4.8) Miller et al. 2008

Bottom following No Best estimate

Reversals Gaussian 1.0 (0) Best estimate

Reversal dive rate (m/s) Gaussian 0.0 (0.0) Best estimate

Time in reversal (s) Gaussian 708 (552) Miller et al. 2008

Surface interval (s) Gaussian 462 (360) Miller et al. 2008

Bout duration* T50 = 8.1, K = 0.9 Best estimate

Surface active Travel Direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.88 (0.27) Miller et al. 2004

Ascent rate (m/s) Gaussian 0.67 (0.43) Amano and Yoshioka 2003

Descent rate (m/s) Gaussian 0.85 (0.05) Amano and Yoshioka 2003

Average depth (m) Gaussian 25.0 (25.0) Amano and Yoshioka 2003

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 408 (114) Amano and Yoshioka 2003

* Sigmoidal function: T50 is the midpoint in minutes, K is the steepness
D-270 Acoustic Propagation and Marine Mammal Exposure Modeling

D.17. Spinner Dolphins

Table D-17. Distribution data for spinner dolphins based on pantropical spotted dolphin data. Unless otherwise 

indicated, numbers in the Value column represent means with their standard deviations in brackets after.

Behavior Variable Value Reference

Day dive Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 0.72 (0.83) Würsig et al. 1994

Ascent rate (m/s) Gaussian 0.42 (0.24) Pantropical spotted dolphins

Descent rate (m/s) Gaussian 0.58 (0.34) Pantropical spotted dolphins

Average depth (m) Gaussian 22.1 (15.71) Pantropical spotted dolphins

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 59.4 (293.4) Pantropical spotted dolphins

Night dive Travel direction Correlated random walk Best estimate

Perturbation value 10 Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 1.36 (0.83) Würsig et al. 1994

Ascent rate (m/s) Gaussian 0.74 (0.41) Pantropical spotted dolphins

Descent rate (m/s) Gaussian 0.93 (0.54) Pantropical spotted dolphins

Average depth (m) Gaussian 24 (27.1) Pantropical spotted dolphins

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Pantropical spotted dolphins

Number of reversals 3 (1) Pantropical spotted dolphins

Time in reversal log (s) 39 (55.2) Pantropical spotted dolphins

Surface interval (s) Gaussian 47.4 (106.8) Pantropical spotted dolphins
Gulf of Mexico G&G Activities Programmatic EIS D-271

D.18. Striped Dolphins 

Table D-18. Distribution data for striped dolphins based on pantropical spotted dolphin data. Unless otherwise 

indicated, numbers in the Value column represent means with their standard deviations in brackets after. 

Behavior Variable Value Reference

Day dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 3.035 (1.22) Au and Perryman 1982

Ascent rate (m/s) Gaussian 0.6 (0.37) Minamikawa et al. 2003

Descent rate (m/s) Gaussian 0.538 (0.343) Minamikawa et al. 2003

Average depth (m) Gaussian 22.6 (17.5) Minamikawa et al. 2003

Bottom following No Best estimate

Reversals No Best estimate

Surface interval (s) Gaussian 55.7 (32.1) Minamikawa et al. 2003

Night dive Travel direction Random walk Best estimate

Termination coefficient 0.2 Best estimate

Travel rate (m/s) Gaussian 3.035 (1.22) Au and Perryman 1982

Ascent rate (m/s) Gaussian 1.542 (0.709) Minamikawa et al. 2003

Descent rate (m/s) Gaussian 1.463 (0.668) Minamikawa et al. 2003

Average depth (m) Gaussian 126.7 (120.9) Minamikawa et al. 2003

Bottom following No Best estimate

Reversals Gaussian Best estimate

Probability of reversal 0.5 Pantropical spotted dolphins

Number of reversals 3 (1) Pantropical spotted dolphins

Time in reversal log (s) 39 (55.2) Pantropical spotted dolphins

Surface interval (s) Gaussian 65.8 (32) Minamikawa et al. 2003
D-272 Acoustic Propagation and Marine Mammal Exposure Modeling

D.19. Animal Movement Modeling Species and Groups

Table D-19. Group name and species in each animal movement modeling group. 

Group name Species represented

Atlantic spotted dolphins Atlantic spotted dolphins

Beaked whales Cuvier’s beaked whales, Blainville’s beaked whales, Gervais’ beaked whales

Common bottlenose dolphins Common bottlenose dolphins

Bryde's whales Bryde's whales

Killer whales Killer whales

Pantropical spotted dolphins Pantropical spotted dolphins, Clymene dolphins, Spinner dolphins, Striped 

dolphins

Risso’s dolphins Risso’s dolphins

Rough-toothed dolphins Rough-toothed dolphins, False killer whales, Pygmy killer whales

Short-finned pilot whales Short-finned pilot whales, Fraser’s dolphins, Kogia spp. (dwarf sperm whales, 

pygmy sperm whales), Melon-headed whales

Sperm whales Sperm whales
Gulf of Mexico G&G Activities Programmatic EIS D-273

Appendix E. Per-Pulse Acoustic Field Maps and Radii

The 3-D per-pulse acoustic fields used as inputs for acoustic exposure analysis were also processed to 

provide two other products:

• Plan-view maps of the acoustic field around the sources 

• Tables of ranges to various isopleths (radii tables) for each source

The maps and radii tables are, respectively, 2-D and 1-D projections of the 3-D sound fields, which serve 

as quality assurance checkpoints to verify the acoustic modeling output and control the results of the 

exposure simulation. 

Maps were created from the 3-D grid of the acoustic pressure levels by taking the maximum-over-depth 

value at each horizontal sampling location. The maps therefore represent the maximum received acoustic 

level over all depths at each location.

The ranges to isopleths in the radii tables are provided as two statistical estimates:

• The maximum range (Rmax, in meters) 

• The 95% range (R95%, in meters) 

Given a regularly gridded spatial distribution of sound levels, the R95% for a given sound level is defined 

as the radius of the circle, centered on the source, encompassing 95% of the grid points with sound levels 

at or above the given value. This definition is meaningful in terms of potential effects on animals because, 

regardless of the shape of the contour for a given sound level, R95% is the range from the source beyond 

which only 5% of a uniformly distributed population would be exposed to sounds at or above that level. 

The Rmax for a given sound level is the maximum distance at which the specified received level occurs 

(equivalent to R100%). It is more conservative than R95%, but could be relevant for defining exclusion zones 

to avoid any chance of exposures above the specified level. For cases where the volume ensonified to a 

specific level is discontinuous and small pockets of higher received levels occur far beyond the main 

ensonified volume (e.g., due to convergence), the Rmax can be much larger than R95%. Interpretation of 

these cases can be difficult if Rmax if not presented with R95%. 

Example modeling results the 8000 in3

 airgun array at site CM3, located in the Central-Slope zone at 750 

m water depth, are presented below as maps of unweighted, per-pulse SEL, and SPL fields (Figure E-1 to 

Figure E-4). Site CM3 results are present as example results because that site is centrally located within 

the Gulf (see Tables 48–50 for all modeling site locations). The corresponding radii tables for the site are 

shown in Table E-1 to Table E-4 for Seasons 1 (January to March) and 3 (July to September) in SEL and 

rms SPL metrics with all applicable M-weighted filtering. 

Example modeling results for the geotechnical survey sources at Box 4, an animat movement simulation 

box, are presented below as maps of unweighted, per-pulse SEL and SPL fields (Figure E-5 to Figure 

E-6, Table E-6 to Table E-12). Box 4 results are present as example results because that box is centrally 

located within the Gulf (See Table 51 for all box locations.) Radii tables for each site and season and for 

all sources have been calculated and can be accessed at https://www.boem.gov/Gulf-of-MexicoGeological-and-Geophysical-Activities-Programmatic-EIS/#Additional. 
D-274 Acoustic Propagation and Marine Mammal Exposure Modeling

E.1. 8000 in3 Airgun Array

Figure E-1. 8000 in3 airgun array at the Central-Slope region (Site CM3), Season 1 (February): 

Broadband (10–5,000 Hz) maximum-over-depth per-pulse SEL field. Blue contours indicate 

water depth in meters.
Gulf of Mexico G&G Activities Programmatic EIS D-275

Figure E-2. 8000 in3 airgun array at the Central-Slope region (Site CM3), Season 1 (February): 

Broadband (10–5,000 Hz) maximum-over-depth rms SPL field. Blue contours indicate water 

depth in meters.
D-276 Acoustic Propagation and Marine Mammal Exposure Modeling

Figure E-3. 8000 in3 airgun array at the Central-Slope region (Site CM3), Season 3 (September)

(February): Broadband (10–5,000 Hz) maximum-over-depth per-pulse SEL field. Blue 

contours indicate water depth in meters.
Gulf of Mexico G&G Activities Programmatic EIS D-277

Figure E-4. 8000 in3 airgun array at the Central-Slope region (Site CM3), Season 3 (September)

(February): Broadband (10–5,000 Hz) maximum-over-depth rms SPL field. Blue contours 

indicate water depth in meters.
D-278 Acoustic Propagation and Marine Mammal Exposure Modeling

Table E-1. 8000 in3 airgun array at Site CM3, Season 1 (February): Ranges to specific threshold levels (SEL).

SEL Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

210 10 10 10 10 < 10 < 10

200 50 40 40 40 10 10 < 10 < 10

190 150 120 140 120 50 50 30 30

180 500 400 470 380 160 140 120 100

170 2100 1800 2000 1400 520 440 400 330

160 5900 4400 5400 4000 2900 1500 1300 1100

150 23000 17000 23000 16000 14000 9700 10000 9300

140 > 50000 > 50000 > 50000 > 50000 32000 21000 25000 18000

130 > 50000 > 50000 50000 36000

120 > 50000 > 50000

110 

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and 

without auditory frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and highfrequency cetaceans (HFC). 

Units: rms SPL (dB re 1 μPa2

·s). 

Table E-2. 8000 in3 airgun array at Site CM3, Season 1 (February): Ranges to specific threshold levels (rms SPL).

rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

210 50 41 50 40 10 10 10 10

200 170 140 160 130 60 50 40 30

190 470 390 470 370 180 150 120 100

180 1900 1300 1500 1200 590 480 460 370

170 6700 5300 6400 4700 2400 1100 1200 900

160 19000 15000 18000 14000 11000 8500 9800 7200

150 50000 36000 50000 35000 26000 17000 23000 15000

140 > 50000 > 50000 > 50000 > 50000 47000 32000 43000 27000

130 > 50000 > 50000 > 50000 > 50000

120 

110 

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without

auditory frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency 

cetaceans (HFC). Units: rms SPL (dB re 1 μPa).
Gulf of Mexico G&G Activities Programmatic EIS D-279

Table E-3. 8000 in3 airgun array at Site CM3, Season 3 (September): Ranges to specific threshold levels (SEL).

SEL Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

210 10 10 10 10 < 10 < 10

200 50 40 40 40 10 10 < 10 < 10

190 150 120 140 120 50 50 30 30

180 490 400 470 380 160 140 120 100

170 2000 1700 1900 1400 510 430 390 330

160 5900 4200 5600 3900 2900 1700 1300 1100

150 21000 16000 19000 16000 15000 9300 9900 9100

140 > 50000 > 50000 > 50000 > 50000 23000 19000 23000 16000

130 48000 33000 40000 29000

120 > 50000 > 50000 > 50000 > 50000

110 

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and 

without auditory frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and highfrequency cetaceans (HFC).

Units: rms SPL (dB re 1 μPa2

·s). 

Table E-4. 8000 in3 airgun array at Site CM3, Season 3 (September): Ranges to specific threshold levels (rms SPL).

rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

210 50 41 50 40 10 10 10 10

200 170 140 160 130 60 50 40 30

190 470 390 470 370 180 150 120 100

180 1900 1300 1500 1200 590 470 460 370

170 6500 5300 6400 5000 2600 1200 1200 910

160 19000 15000 19000 14000 12000 9100 9700 7200

150 49000 35000 49000 34000 21000 16000 18000 15000

140 > 50000 > 50000 > 50000 > 50000 37000 28000 32000 26000

130 > 50000 > 50000 > 50000 > 50000

120 

110 

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without 

auditory frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency 

cetaceans (HFC). Units: rms SPL (dB re 1 μPa).
D-280 Acoustic Propagation and Marine Mammal Exposure Modeling

E.2. High-resolution Sources

Figure E-5. Box 4 geotechnical sources: Maximum-over-depth sound pressure levels during Season 1 

(February).
Gulf of Mexico G&G Activities Programmatic EIS D-281

Figure E-6. Box 4 geotechnical sources: Maximum-over-depth sound pressure levels during Season 3 

(September).
D-282 Acoustic Propagation and Marine Mammal Exposure Modeling

E.2.1. 90 in3 Airgun/Boomer

Table E-5. Box 4, Season 1 (February), ranges to specific threshold levels for a 90 in3 single airgun.

SEL rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

190 200 < 10 < 10 < 10 < 10

180 190 14 14 14 14 < 10 < 10 < 10 < 10

170 180 45 42 42 42 14 14 14 14

160 170 120 110 110 110 54 54 45 45

150 160 370 360 360 350 160 160 130 130

140 150 1300 1300 1300 1200 500 490 410 390

130 140 8900 4800 8900 4200 1800 1700 1300 1300

120 130 28000 19000 28000 18000 17000 9400 17000 8300

110 120 > 50000 > 50000 > 50000 > 50000 35000 25000 35000 23000

100 110 > 50000 > 50000 > 50000 > 50000

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without 

auditory frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency 

cetaceans (HFC). Units: SEL (dB re 1 μPa2

·s); 

rms SPL (dB re 1 μPa).

Table E-6. Box 4, Season 3 (September), ranges to specific threshold levels for a 90 in3 single airgun.

SEL rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

190 200 < 10 < 10 < 10 < 10

180 190 14 14 14 14 < 10 < 10 < 10 < 10

170 180 42 42 41 41 14 14 14 14

160 170 120 110 110 110 54 54 45 45

150 160 370 360 360 350 160 160 130 130

140 150 1300 1300 1300 1200 500 490 410 400

130 140 8400 5200 8300 4000 1900 1700 1400 1300

120 130 27000 18000 25000 18000 14000 9100 13000 8300

110 120 > 50000 > 50000 50000 37000 35000 24000 35000 21000

100 110 > 50000 > 50000 > 50000 > 50000 > 50000 > 50000

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without

auditory frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency 

cetaceans (HFC). Units: SEL (dB re 1 μPa2

·s); 

rms SPL (dB re 1 μPa).
Gulf of Mexico G&G Activities Programmatic EIS D-283

E.2.2. Multibeam Sonar

Table E-7. Box 4, Season 1 (February), ranges to specific threshold levels for a multibeam sonar.

SEL rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

150 160 < 5 < 5 < 5 < 5 < 5 < 5 

140 150 25 25 5 5 5 5 

130 140 65 60 30 25 35 30

120 130 140 120 < 5 < 5 75 70 80 75

110 120 240 210 5 5 150 140 160 150

100 110 380 330 30 25 260 230 280 240

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without auditory 

frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency cetaceans 

(HFC). Units: SEL (dB re 1 μPa2

·s); 

rms SPL (dB re 1 μPa).

Table E-8. Box 4, Season 3 (September), ranges to specific threshold levels for a multibeam sonar.

SEL rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

150 160 < 5 < 5 < 5 < 5 < 5 < 5 

140 150 25 25 5 5 5 5 

130 140 65 60 30 25 35 30

120 130 130 120 < 5 < 5 75 70 80 70

110 120 220 200 5 5 150 130 160 140

100 110 350 300 30 30 240 220 260 230

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without auditory 

frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency cetaceans 

(HFC). Units: SEL (dB re 1 μPa2

·s); 

rms SPL (dB re 1 μPa).
D-284 Acoustic Propagation and Marine Mammal Exposure Modeling

E.2.3. Side-scan Sonar

Table E-9. Box 4, Season 1 (February), ranges to specific threshold levels for a side-scan sonar.

SEL rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

160 170 < 5 < 5 < 5 < 5 < 5 < 5 

150 160 65 65 30 30 35 35

140 150 140 140 90 85 95 90

130 140 260 250 < 5 < 5 190 180 200 190

120 130 420 370 55 55 340 320 360 330

110 120 590 500 130 120 530 440 540 460

100 110 790 600 240 230 700 580 710 580

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without auditory 

frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency cetaceans 

(HFC). Units: SEL (dB re 1 μPa2

·s);

rms SPL (dB re 1 μPa).

Table E-10. Box 4, Season 3 (September), ranges to specific threshold levels for a side-scan sonar.

SEL rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

160 170 < 5 < 5 < 5 < 5 < 5 < 5 

150 160 65 65 30 30 35 35

140 150 140 130 90 85 95 90

130 140 240 230 < 5 < 5 190 180 190 180

120 130 410 350 55 50 330 310 350 330

110 120 580 480 130 120 520 430 520 430

100 110 760 580 240 230 680 560 700 570

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without auditory 

frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency cetaceans 

(HFC). Units: SEL (dB re 1 μPa2

·s);

rms SPL (dB re 1 μPa).
Gulf of Mexico G&G Activities Programmatic EIS D-285

E.2.4. Sub-bottom Profiler 

Table E-11. Box 4, Season 1 (February), ranges to specific threshold levels for a sub-bottom profiler.

SEL rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

150 160 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 

140 150 8 8 8 8 8 8 8 8 

130 140 17 17 16 15 17 17 17 17

120 130 61 59 45 44 61 59 61 59

110 120 150 150 110 110 150 140 150 140

100 110 750 600 440 370 750 600 750 600

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without auditory 

frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency cetaceans 

(HFC). Units: SEL (dB re 1 μPa2

·s); 

rms SPL (dB re 1 μPa).

Table E-12. Box 4, Season 3 (September), ranges to specific threshold levels for a sub-bottom profiler.

SEL rms 

SPL

Unweighted Type I M-Weighting

LFC MFC HFC

Rmax R95% Rmax R95% Rmax R95% Rmax R95%

150 160 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 

140 150 8 8 8 8 8 8 8 8 

130 140 17 17 16 15 17 17 17 17

120 130 61 59 45 44 61 59 61 59

110 120 160 150 110 110 150 140 150 140

100 110 770 610 440 370 750 600 750 600

Maximum (Rmax, m) and 95% (R95%, m) horizontal distance from the source to modeled broadband maximum-over-depth sound 

level thresholds, with and without auditory 

frequency weighting applied for low-frequency cetaceans (LFC), mid-frequency cetaceans (MFC), and high-frequency cetaceans 

(HFC). Units: SEL (dB re 1 μPa2

·s); 

rms SPL (dB re 1 μPa). 
D-286 Acoustic Propagation and Marine Mammal Exposure Modeling

Appendix F. Annual Exposure Estimates

F.1. Annual Totals for All Sources

Table F-1. 2016 annual exposure estimate totals for all sources. 

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 331.1 33.5 40080.2 133426.8 201356.3

Beaked whales 51.7 2.9 6563.7 235614.8 57492.8

Common bottlenose dolphins 1974.6 151.7 212385.2 653404.8 891037.8

Bryde’s whales 0.4 15.1 77.4 731.8 860.9

Clymene dolphins 431.5 35.0 10240.0 110741.8 201187.1

False killer whales 111.4 10.7 3130.6 25510.6 45216.7

Fraser’s dolphins 52.0 3.2 3006.9 13858.3 22507.8

Killer whales 4.8 0.5 357.6 1492.9 2069.3

Kogia 4426.8 541.4 3824.5 16188.5 35585.5

Melon-headed whales 252.4 16.5 14115.5 68899.5 119722.0

Pantropical spotted dolphins 2550.3 134.2 64870.6 606728.6 947527.9

Pygmy killer whales 83.4 7.5 2281.5 18029.1 30429.7

Risso’s dolphins 105.9 14.5 2608.6 27061.9 48495.8

Rough-toothed dolphins 150.8 15.1 5401.8 37666.3 67023.8

Short-finned pilot whales 68.1 7.6 3426.8 19258.3 38823.6

Sperm whales 44.8 2.4 10872.7 43503.7 93979.5

Spinner dolphins 253.1 9.4 6328.8 82778.6 160968.7

Striped dolphins 174.2 11.1 4295.8 44037.5 75388.5
Gulf of Mexico G&G Activities Programmatic EIS D-287

Table F-2. 2017 annual exposure estimate totals for all sources.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 425.1 33.7 59630.6 175824.7 244098.4

Beaked whales 45.1 1.8 5870.3 204860.9 50231.7

Common bottlenose dolphins 2757.9 111.3 341522.1 966790.3 1283476.0

Bryde’s whales 0.3 12.6 62.7 605.0 724.2

Clymene dolphins 360.6 21.3 8795.2 93767.5 165628.8

False killer whales 99.9 8.0 2879.5 22516.7 38959.8

Fraser’s dolphins 47.1 2.3 2719.2 12240.7 19386.6

Killer whales 4.5 0.5 332.0 1351.6 1833.6

Kogia 3991.0 493.2 3488.7 14520.1 31629.3

Melon-headed whales 227.5 12.2 12607.0 60546.5 103396.1

Pantropical spotted dolphins 2319.6 98.6 59828.3 548764.4 843785.8

Pygmy killer whales 75.1 5.7 2055.5 15845.3 26126.8

Risso’s dolphins 95.0 12.3 2309.0 23594.5 41516.2

Rough-toothed dolphins 142.0 11.8 5959.5 36133.7 61548.4

Short-finned pilot whales 54.0 4.8 2635.1 14972.4 29918.0

Sperm whales 40.4 1.4 9213.3 36832.3 79611.9

Spinner dolphins 244.7 8.5 6129.9 78708.7 153523.0

Striped dolphins 153.6 7.5 3862.8 38903.9 65281.2
D-288 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-3. 2018 annual exposure estimate totals for all sources.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 290.2 25.5 36272.0 117295.4 173452.2

Beaked whales 44.4 2.7 5585.4 195022.1 47714.9

Common bottlenose dolphins 1784.9 90.3 198079.4 598127.8 804687.8

Bryde’s whales 0.3 13.3 67.0 618.4 723.4

Clymene dolphins 376.4 32.7 8786.2 93293.4 171405.6

False killer whales 96.3 10.0 2687.6 21389.7 38221.2

Fraser’s dolphins 45.3 3.0 2549.0 11575.0 18847.7

Killer whales 4.1 0.4 299.9 1229.9 1715.8

Kogia 3710.5 468.1 3226.1 13379.4 29285.6

Melon-headed whales 219.1 15.5 11957.0 57389.9 99683.7

Pantropical spotted dolphins 2157.9 116.7 54470.9 499090.9 786512.4

Pygmy killer whales 71.8 6.9 1945.2 15048.9 25668.9

Risso’s dolphins 91.6 12.9 2226.9 22558.6 40690.5

Rough-toothed dolphins 131.1 13.9 4703.2 31907.1 56928.3

Short-finned pilot whales 61.3 7.4 3024.1 16718.6 33605.6

Sperm whales 38.1 2.1 9330.0 36576.4 78417.3

Spinner dolphins 212.1 7.9 5254.2 66746.3 129459.8

Striped dolphins 149.3 10.1 3637.0 36541.7 63137.2
Gulf of Mexico G&G Activities Programmatic EIS D-289

Table F-4. 2019 annual exposure estimate totals for all sources.

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 423.0 40.2 61334.2 174705.4 237351.8

Beaked whales 38.0 1.6 4259.4 162134.0 39332.0

Common bottlenose dolphins 2833.4 161.0 352798.8 977108.3 1286763.9

Bryde’s whales 0.3 10.2 48.2 481.3 571.5

Clymene dolphins 282.8 19.7 6587.0 72912.8 132307.6

False killer whales 76.6 6.5 2175.1 17631.1 30853.9

Fraser’s dolphins 35.6 1.9 2010.0 9654.3 15405.2

Killer whales 3.4 0.4 240.9 1031.1 1429.7

Kogia 2889.2 380.6 2554.4 11427.6 24827.9

Melon-headed whales 171.2 9.5 9239.0 47547.6 81651.0

Pantropical spotted dolphins 1759.0 86.0 43742.7 419737.6 657701.8

Pygmy killer whales 56.9 4.5 1505.4 12277.6 20528.0

Risso’s dolphins 75.2 9.5 1761.0 18123.5 32923.3

Rough-toothed dolphins 114.5 10.2 5244.4 30192.3 51110.5

Short-finned pilot whales 42.6 4.1 2005.0 12154.5 24322.1

Sperm whales 28.9 1.3 6248.9 27270.6 56706.5

Spinner dolphins 188.1 7.5 4550.8 59622.5 119366.8

Striped dolphins 118.2 6.7 2855.3 29936.2 51432.8
D-290 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-5. 2020 annual exposure estimate totals for all sources.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 290.5 23.4 36255.0 116698.1 171995.1

Beaked whales 46.7 1.7 5591.0 190777.4 46608.9

Common bottlenose dolphins 1788.3 81.9 198182.1 596824.1 801708.1

Bryde’s whales 0.3 12.4 61.3 565.8 672.5

Clymene dolphins 348.1 20.9 8468.2 87614.7 155501.5

False killer whales 95.4 7.6 2700.3 20828.4 36168.0

Fraser’s dolphins 43.9 2.1 2572.2 11393.8 17978.9

Killer whales 4.3 0.4 316.2 1258.4 1703.8

Kogia 3857.7 475.2 3346.4 13664.1 29421.3

Melon-headed whales 212.9 10.6 12084.1 56791.0 96371.0

Pantropical spotted dolphins 2215.8 94.3 57221.4 511036.9 789057.3

Pygmy killer whales 71.8 5.4 1975.1 14787.7 24406.7

Risso’s dolphins 93.7 11.4 2202.9 21914.2 38821.7

Rough-toothed dolphins 129.5 10.6 4704.1 31102.5 54226.7

Short-finned pilot whales 50.8 4.3 2546.7 14163.3 28103.6

Sperm whales 38.1 1.5 8517.9 33340.0 70032.5

Spinner dolphins 238.2 8.3 5935.9 73012.9 142804.9

Striped dolphins 147.6 7.3 3708.3 36266.5 61116.2
Gulf of Mexico G&G Activities Programmatic EIS D-291

Table F-6. 2021 annual exposure estimate totals for all sources.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 417.0 35.4 59474.2 171905.7 236363.4

Beaked whales 47.1 2.7 5398.0 187604.0 45590.3

Common bottlenose dolphins 2763.1 115.9 341320.6 955742.1 1266130.0

Bryde’s whales 0.3 13.3 66.8 597.2 693.3

Clymene dolphins 369.8 32.7 8603.4 89618.0 166262.4

False killer whales 94.1 9.6 2708.4 20760.0 37075.3

Fraser’s dolphins 43.3 2.8 2516.9 11279.5 18255.5

Killer whales 4.0 0.4 290.5 1176.3 1643.8

Kogia 3659.4 457.5 3153.7 12984.2 28092.0

Melon-headed whales 208.1 14.0 11669.4 55474.4 95823.2

Pantropical spotted dolphins 2096.5 116.1 52890.5 476698.9 757643.4

Pygmy killer whales 69.4 6.7 1895.4 14427.9 24697.5

Risso’s dolphins 92.5 12.2 2171.1 21521.7 39337.2

Rough-toothed dolphins 136.0 14.0 5774.8 33915.3 58878.2

Short-finned pilot whales 58.9 7.0 2981.0 16327.5 32625.2

Sperm whales 36.3 2.3 8733.4 33804.8 69850.9

Spinner dolphins 209.9 8.1 5169.9 63322.2 124218.1

Striped dolphins 146.0 10.0 3547.6 34969.4 60995.9
D-292 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-7. 2022 annual exposure estimate totals for all sources.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 302.4 30.4 38803.6 122141.9 177946.6

Beaked whales 41.9 1.7 5076.4 178787.5 43303.5

Common bottlenose dolphins 1890.0 134.3 210451.4 624454.4 835161.0

Bryde’s whales 0.3 11.2 57.0 530.3 627.5

Clymene dolphins 315.9 20.6 7735.4 81413.5 145490.2

False killer whales 84.5 6.9 2452.5 19325.5 33630.0

Fraser’s dolphins 39.0 1.9 2355.5 10607.9 16763.3

Killer whales 3.8 0.4 285.9 1162.9 1580.0

Kogia 3585.0 419.9 3054.8 12695.9 27371.7

Melon-headed whales 188.9 9.8 11040.9 52809.2 89767.1

Pantropical spotted dolphins 1998.7 93.2 51950.6 472822.4 732288.9

Pygmy killer whales 63.5 4.9 1780.6 13685.7 22634.5

Risso’s dolphins 83.6 10.3 2012.3 20305.1 36265.7

Rough-toothed dolphins 117.1 10.1 4547.2 29545.9 51348.7

Short-finned pilot whales 46.0 4.1 2347.1 13294.3 26435.6

Sperm whales 33.6 1.5 7627.1 30668.4 63959.6

Spinner dolphins 212.0 8.0 5399.8 67309.9 132699.6

Striped dolphins 133.3 7.2 3375.6 33603.6 56934.9
Gulf of Mexico G&G Activities Programmatic EIS D-293

Table F-8. 2023 annual exposure estimate totals for all sources.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 397.5 32.7 58303.6 164824.3 221780.8

Beaked whales 36.5 1.6 4243.7 151708.3 37134.2

Common bottlenose dolphins 2687.0 102.8 339639.6 938321.5 1229214.3

Bryde’s whales 0.3 9.9 47.0 454.3 540.4

Clymene dolphins 276.7 18.7 6501.2 69608.5 125034.2

False killer whales 75.9 6.5 2164.3 16774.1 29231.5

Fraser’s dolphins 35.2 1.8 1991.4 9126.7 14537.6

Killer whales 3.4 0.4 240.0 984.3 1351.0

Kogia 2861.0 373.8 2526.2 10742.9 23321.6

Melon-headed whales 168.6 9.4 9148.2 44841.9 76892.5

Pantropical spotted dolphins 1719.9 78.8 43334.2 399580.5 621470.2

Pygmy killer whales 56.4 4.6 1504.2 11676.8 19464.7

Risso’s dolphins 73.1 9.3 1710.1 17308.8 30955.1

Rough-toothed dolphins 112.5 9.9 5076.5 28662.8 48301.8

Short-finned pilot whales 41.8 4.0 1982.0 11522.5 23062.6

Sperm whales 29.6 1.3 6530.7 26650.9 56439.5

Spinner dolphins 182.7 6.6 4450.0 56546.1 111110.8

Striped dolphins 115.6 6.3 2821.3 28522.2 48514.8
D-294 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-9. 2024 annual exposure estimate totals for all sources.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 269.3 22.6 35542.4 109856.5 157436.0

Beaked whales 37.7 1.7 4753.2 156583.6 38031.8

Common bottlenose dolphins 1721.5 74.9 196862.6 579403.1 766053.4

Bryde’s whales 0.3 10.2 53.2 469.8 554.3

Clymene dolphins 288.4 19.0 7196.6 72741.3 129402.6

False killer whales 76.7 6.6 2296.8 17163.3 29795.7

Fraser’s dolphins 35.3 1.7 2209.3 9391.4 14760.2

Killer whales 3.4 0.3 266.7 1035.8 1390.7

Kogia 3410.8 377.2 2858.4 11164.7 23941.2

Melon-headed whales 170.4 8.9 10344.7 46630.5 78841.0

Pantropical spotted dolphins 1814.1 82.8 48318.0 419823.7 647642.4

Pygmy killer whales 57.6 4.7 1668.1 12140.9 20053.1

Risso’s dolphins 76.0 9.3 1830.2 18091.8 31995.2

Rough-toothed dolphins 106.3 9.4 4200.0 26314.7 45535.6

Short-finned pilot whales 42.0 3.9 2210.3 11900.0 23598.7

Sperm whales 31.6 1.5 7443.5 27656.6 57735.6

Spinner dolphins 189.4 6.6 4961.2 59253.3 115261.0

Striped dolphins 121.1 6.4 3136.7 29890.1 50373.1
Gulf of Mexico G&G Activities Programmatic EIS D-295

Table F-10. 2025 annual exposure estimate totals for all sources.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 417.5 39.8 61360.8 172104.3 230498.1

Beaked whales 35.4 1.6 4314.1 146016.7 35545.7

Common bottlenose dolphins 2819.0 157.5 352480.7 970712.7 1269758.3

Bryde’s whales 0.2 9.6 48.4 439.4 519.1

Clymene dolphins 269.9 18.4 6573.7 67663.6 121148.0

False killer whales 72.7 6.4 2189.7 16242.2 28188.8

Fraser’s dolphins 33.5 1.7 2038.4 8848.8 13959.3

Killer whales 3.2 0.3 242.8 958.5 1298.3

Kogia 3036.5 355.7 2587.1 10383.1 22339.9

Melon-headed whales 160.4 8.7 9365.2 43386.6 73728.2

Pantropical spotted dolphins 1680.1 77.9 43875.2 388177.6 601739.4

Pygmy killer whales 54.0 4.5 1520.5 11291.9 18750.8

Risso’s dolphins 71.0 8.8 1691.1 16794.8 29887.1

Rough-toothed dolphins 109.6 10.0 5256.8 28351.1 47408.9

Short-finned pilot whales 40.0 3.9 2024.0 11190.6 22263.7

Sperm whales 29.1 1.4 6721.2 25716.3 53768.8

Spinner dolphins 176.1 6.3 4499.6 54651.1 106767.8

Striped dolphins 112.7 6.2 2854.7 27700.9 46946.9
D-296 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-11. Decade annual exposure estimate totals for all sources.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 3563.5 317.2 487056.5 1458783.3 2052278.6

Beaked whales 424.6 20.1 51655.2 1809109.2 440985.8

Common bottlenose dolphins 23019.7 1181.6 2743722.5 7860889.1 10433990.6

Bryde’s whales 3.0 117.8 588.8 5493.2 6487.0

Clymene dolphins 3320.1 239.0 79487.0 839375.0 1513368.0

False killer whales 883.5 78.8 25384.9 198141.7 347341.0

Fraser’s dolphins 410.3 22.4 23968.9 107976.5 172402.1

Killer whales 38.8 4.1 2872.4 11681.7 16015.8

Kogia 35427.9 4342.6 30620.3 127150.4 275815.8

Melon-headed whales 1979.7 115.1 111570.8 534317.0 915875.8

Pantropical spotted dolphins 20311.8 978.5 520502.4 4742461.5 7385369.4

Pygmy killer whales 659.8 55.4 18131.6 139211.8 232760.7

Risso’s dolphins 857.6 110.4 20523.1 207274.9 370887.7

Rough-toothed dolphins 1249.5 115.1 50868.4 313791.7 542311.0

Short-finned pilot whales 505.5 51.1 25182.1 141502.0 282758.8

Sperm whales 350.6 16.7 81238.9 322020.0 680502.4

Spinner dolphins 2106.2 77.1 52680.2 661951.7 1296180.6

Striped dolphins 1371.6 78.7 34095.0 340372.2 580121.5
Gulf of Mexico G&G Activities Programmatic EIS D-297

F.2. Annual Exposure Estimates for Each Source

F.2.1. 2016

Table F-12. 2016 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 3.4 0.2 164.7 2667.7 6011.5

Beaked whales 1.8 0.1 186.4 15183.3 3562.4

Common bottlenose dolphins 7.3 0.6 396.6 7010.8 13939.6

Bryde’s whales 0.0 0.3 2.4 41.2 50.6

Clymene dolphins 12.4 0.9 307.8 5925.8 10276.6

False killer whales 2.9 0.1 80.4 1363.4 2334.0

Fraser’s dolphins 1.1 0.0 98.1 773.5 1330.2

Killer whales 0.1 0.0 12.4 87.5 123.4

Kogia 153.7 12.1 121.8 960.1 2319.9

Melon-headed whales 5.3 0.0 451.8 3911.0 7345.2

Pantropical spotted dolphins 93.0 7.7 2247.7 36435.7 54177.4

Pygmy killer whales 2.2 0.0 62.1 988.3 1580.3

Risso’s dolphins 2.4 0.2 85.1 1530.8 2738.8

Rough-toothed dolphins 3.6 0.1 99.0 1775.4 3204.4

Short-finned pilot whales 1.1 0.0 77.6 864.2 1934.7

Sperm whales 1.4 0.2 327.0 2391.4 5749.3

Spinner dolphins 8.4 0.5 219.1 5464.7 11120.2

Striped dolphins 5.7 0.4 140.6 2542.7 4194.2
D-298 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-13. 2016 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 290.5 30.6 37123.8 114136.0 163006.9

Beaked whales 33.0 2.1 3289.8 141081.3 35503.2

Common bottlenose dolphins 1852.8 133.0 208355.1 603788.8 796124.2

Bryde’s whales 0.2 10.1 36.7 444.8 534.2

Clymene dolphins 278.5 26.4 5339.5 65882.6 123800.0

False killer whales 76.0 8.8 1710.2 15509.1 28278.4

Fraser’s dolphins 36.4 2.9 1463.8 8294.8 14018.2

Killer whales 3.3 0.4 182.0 853.8 1256.3

Kogia 1704.3 376.1 1827.1 9551.2 21540.5

Melon-headed whales 176.0 14.7 6772.6 40937.4 73612.3

Pantropical spotted dolphins 1541.9 84.9 32815.2 348649.0 560399.0

Pygmy killer whales 56.4 6.0 1202.0 10803.8 18880.2

Risso’s dolphins 67.4 10.6 1495.2 15913.9 29352.4

Rough-toothed dolphins 106.9 12.8 3633.2 24669.3 44010.9

Short-finned pilot whales 49.5 6.9 1725.8 12049.3 24878.6

Sperm whales 26.8 1.3 5337.1 26668.0 59889.8

Spinner dolphins 158.6 6.4 3179.1 47035.2 92654.6

Striped dolphins 108.7 7.8 2199.9 25673.0 45301.4
Gulf of Mexico G&G Activities Programmatic EIS D-299

Table F-14. 2016 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 15.4 1.2 1948.8 13153.1 26634.9

Beaked whales 4.7 0.1 2347.0 63466.0 15214.7

Common bottlenose dolphins 34.7 0.9 2284.2 34068.7 68051.1

Bryde’s whales 0.1 1.1 30.9 200.9 229.3

Clymene dolphins 51.5 3.2 3108.5 31042.9 55785.4

False killer whales 11.2 1.0 847.6 6504.1 11321.1

Fraser’s dolphins 4.9 0.1 1119.1 3800.5 5931.0

Killer whales 0.5 0.1 118.3 437.5 556.7

Kogia 2149.2 40.1 1449.9 4496.0 9696.3

Melon-headed whales 24.3 0.6 5331.1 19034.4 32091.0

Pantropical spotted dolphins 311.8 7.5 20302.3 177190.6 274838.2

Pygmy killer whales 8.7 0.8 644.0 4698.6 7698.9

Risso’s dolphins 12.1 1.7 658.9 7710.5 13746.5

Rough-toothed dolphins 13.7 1.1 1055.3 8450.8 15393.5

Short-finned pilot whales 6.4 0.4 1249.2 4986.4 9964.0

Sperm whales 8.4 0.2 4068.0 11273.2 23183.1

Spinner dolphins 31.3 0.2 1984.1 24292.3 47726.1

Striped dolphins 21.1 0.8 1327.7 12638.6 21468.6
D-300 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-15. 2016 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 21.8 0.4 840.3 3454.1 5677.3

Beaked whales 12.3 0.5 740.4 15880.5 3212.4

Common bottlenose dolphins 79.9 6.4 1322.0 8454.5 12832.0

Bryde’s whales 0.1 3.7 7.5 44.8 46.9

Clymene dolphins 89.1 4.5 1484.1 7890.5 11325.0

False killer whales 21.3 0.9 492.4 2134.0 3283.1

Fraser’s dolphins 9.7 0.2 325.8 989.4 1228.4

Killer whales 1.0 0.1 44.8 114.1 132.8

Kogia 419.6 113.2 425.6 1181.3 2028.8

Melon-headed whales 46.8 1.1 1560.0 5016.7 6673.5

Pantropical spotted dolphins 603.6 34.1 9505.3 44453.4 58113.2

Pygmy killer whales 16.1 0.6 373.4 1538.5 2270.2

Risso’s dolphins 24.0 2.0 369.4 1906.7 2658.2

Rough-toothed dolphins 26.7 1.1 614.3 2769.6 4413.4

Short-finned pilot whales 11.1 0.3 374.2 1358.4 2046.4

Sperm whales 8.2 0.7 1140.7 3171.0 5157.4

Spinner dolphins 54.8 2.4 946.6 5986.4 9468.0

Striped dolphins 38.7 2.0 627.6 3183.2 4424.3
Gulf of Mexico G&G Activities Programmatic EIS D-301

Table F-16. 2016 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 1.5 11.6 24.3

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 13.2 53.3 82.5

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.1 0.1

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.1 0.9 1.6

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0 

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-302 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-17. 2016 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-303

Table F-18. 2016 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 1.0 1.1 4.3 1.4

Beaked whales 0.0 0.1 0.1 3.7 0.0

Common bottlenose dolphins 0.0 10.9 14.1 28.7 8.3

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.2 0.1 

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0 

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-304 Acoustic Propagation and Marine Mammal Exposure Modeling

F.2.2. 2017

Table F-19. 2017 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 1.8 0.0 98.3 1186.5 2811.6

Beaked whales 1.1 0.0 91.9 6722.8 1501.1

Common bottlenose dolphins 5.0 0.3 150.6 2883.8 7197.1

Bryde’s whales 0.0 0.2 1.2 18.1 21.6

Clymene dolphins 5.9 0.5 146.0 2482.2 4989.7

False killer whales 1.1 0.0 40.7 604.5 1113.7

Fraser’s dolphins 0.7 0.0 49.3 359.5 573.1

Killer whales 0.1 0.0 5.4 37.0 54.8

Kogia 80.5 6.3 66.3 450.9 1000.6

Melon-headed whales 3.5 0.1 236.3 1841.0 3166.7

Pantropical spotted dolphins 42.4 3.6 1025.4 15336.8 25861.0

Pygmy killer whales 0.9 0.0 30.5 436.0 748.4

Risso’s dolphins 2.1 0.3 44.9 630.1 1325.3

Rough-toothed dolphins 1.4 0.1 51.4 790.5 1537.5

Short-finned pilot whales 0.9 0.0 45.7 418.6 834.9

Sperm whales 0.5 0.0 99.4 724.3 1020.7

Spinner dolphins 4.3 0.3 111.3 2275.5 5480.2

Striped dolphins 2.7 0.2 65.7 1066.9 2025.8
Gulf of Mexico G&G Activities Programmatic EIS D-305

Table F-20. 2017 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 352.4 30.5 49497.1 142643.3 192650.5

Beaked whales 29.3 1.2 3051.9 128007.2 32312.8

Common bottlenose dolphins 2407.7 86.1 290214.0 812697.3 1039664.0

Bryde’s whales 0.2 8.6 31.3 385.7 469.7

Clymene dolphins 237.8 16.8 4766.0 58336.4 106122.3

False killer whales 69.6 6.4 1615.6 14263.3 25295.6

Fraser’s dolphins 33.4 2.1 1375.0 7624.2 12619.0

Killer whales 3.1 0.4 173.7 804.0 1158.3

Kogia 1578.4 348.0 1715.3 8894.0 19970.3

Melon-headed whales 160.5 11.1 6254.8 37393.8 66375.9

Pantropical spotted dolphins 1430.8 62.3 31083.7 328109.8 516513.5

Pygmy killer whales 51.8 4.4 1107.2 9874.8 16811.3

Risso’s dolphins 61.2 9.0 1365.9 14505.6 26158.1

Rough-toothed dolphins 102.6 9.7 4022.8 24583.6 41975.2

Short-finned pilot whales 40.1 4.5 1425.8 9878.3 20237.6

Sperm whales 24.6 0.7 4681.1 23741.8 53770.0

Spinner dolphins 156.0 5.8 3137.8 46544.4 91603.8

Striped dolphins 97.7 5.3 2038.9 23633.7 40670.8
D-306 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-21. 2017 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 29.0 0.7 7890.2 25800.2 40335.2

Beaked whales 3.8 0.0 2074.1 56206.0 13558.4

Common bottlenose dolphins 121.1 4.3 41316.0 123526.4 204394.8

Bryde’s whales 0.0 0.8 24.3 165.0 193.0

Clymene dolphins 40.0 0.0 2643.0 26420.6 45219.4

False killer whales 10.1 0.9 776.3 5771.4 9674.7

Fraser’s dolphins 4.3 0.0 1004.7 3388.2 5118.5

Killer whales 0.4 0.1 110.9 405.4 498.7

Kogia 1950.8 36.6 1321.2 4103.9 8797.9

Melon-headed whales 21.2 0.0 4738.6 16924.7 27954.6

Pantropical spotted dolphins 280.9 0.0 18918.8 164513.4 248467.6

Pygmy killer whales 7.9 0.7 580.5 4172.5 6575.4

Risso’s dolphins 10.4 1.2 582.4 6809.4 11737.3

Rough-toothed dolphins 13.1 1.0 1235.3 8147.1 13989.8

Short-finned pilot whales 4.6 0.0 898.6 3696.0 7297.5

Sperm whales 8.0 0.0 3481.2 9698.1 20342.7

Spinner dolphins 30.6 0.0 1951.1 23989.5 47094.8

Striped dolphins 18.0 0.0 1197.9 11386.2 18696.2
Gulf of Mexico G&G Activities Programmatic EIS D-307

Table F-22. 2017 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 41.9 1.5 2142.5 6178.9 8275.4

Beaked whales 10.9 0.5 652.4 13921.0 2859.4

Common bottlenose dolphins 224.1 9.8 9814.4 27601.1 32129.4

Bryde’s whales 0.1 3.0 5.8 36.3 39.9

Clymene dolphins 76.8 4.1 1240.3 6528.2 9297.4

False killer whales 19.1 0.8 447.1 1877.4 2875.7

Fraser’s dolphins 8.8 0.2 290.1 868.8 1075.8

Killer whales 0.9 0.0 42.0 105.2 121.8

Kogia 381.2 102.3 385.9 1071.3 1860.5

Melon-headed whales 42.3 1.0 1377.3 4386.9 5898.9

Pantropical spotted dolphins 565.5 32.6 8800.4 40804.4 52943.6

Pygmy killer whales 14.5 0.6 337.3 1361.9 1991.7

Risso’s dolphins 21.3 1.9 315.8 1649.3 2295.4

Rough-toothed dolphins 24.9 1.1 649.9 2611.4 4044.3

Short-finned pilot whales 8.4 0.2 265.0 979.6 1548.0

Sperm whales 7.4 0.6 951.6 2668.1 4478.6

Spinner dolphins 53.9 2.3 929.8 5899.2 9344.3

Striped dolphins 35.2 1.9 560.3 2817.1 3888.5
D-308 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-23. 2017 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 1.5 11.6 24.3

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 13.2 53.3 82.5

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.1 0.1

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.1 0.9 1.6

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-309

Table F-24. 2017 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-310 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-25. 2017 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 1.0 1.1 4.2 1.4

Beaked whales 0.0 0.1 0.1 3.9 0.0

Common bottlenose dolphins 0.0 10.8 14.0 28.3 8.1

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.2 0.1

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-311

F.2.3. 2018

Table F-26. 2018 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-312 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-27. 2018 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 258.5 23.0 33885.6 103132.0 145888.8

Beaked whales 30.0 2.1 2952.3 127359.3 32024.0

Common bottlenose dolphins 1686.8 73.7 194968.1 561859.9 735584.6

Bryde’s whales 0.2 9.2 33.6 406.2 486.1

Clymene dolphins 255.3 25.7 4840.8 59851.4 113381.4

False killer whales 68.6 8.4 1546.5 14014.8 25695.4

Fraser’s dolphins 32.9 2.7 1318.0 7489.7 12714.7

Killer whales 2.9 0.3 162.2 763.3 1129.6

Kogia 1530.4 337.9 1635.0 8564.4 19336.5

Melon-headed whales 158.7 13.9 6085.2 36890.6 66561.4

Pantropical spotted dolphins 1383.6 80.5 29282.7 311665.6 503795.1

Pygmy killer whales 50.8 5.7 1080.8 9734.3 17127.6

Risso’s dolphins 60.9 9.7 1348.2 14350.8 26624.2

Rough-toothed dolphins 96.7 12.0 3279.7 22320.9 39942.9

Short-finned pilot whales 45.9 6.7 1594.6 11153.1 23069.5

Sperm whales 24.1 1.3 4860.1 24193.1 54213.7

Spinner dolphins 140.0 5.7 2803.7 41449.0 81672.3

Striped dolphins 98.4 7.5 1974.7 23087.2 41008.4
Gulf of Mexico G&G Activities Programmatic EIS D-313

Table F-28. 2018 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 13.1 1.1 1666.3 11199.8 22710.5

Beaked whales 4.0 0.1 2001.4 54098.3 12955.0

Common bottlenose dolphins 29.5 0.9 1952.6 28973.5 58068.6

Bryde’s whales 0.0 0.9 26.8 173.5 197.1

Clymene dolphins 44.8 3.2 2668.0 26639.5 48248.8

False killer whales 9.5 0.8 721.9 5551.2 9719.5

Fraser’s dolphins 4.2 0.1 953.1 3239.8 5082.9

Killer whales 0.4 0.1 99.8 370.0 473.7

Kogia 1824.1 34.0 1229.8 3812.2 8230.3

Melon-headed whales 20.7 0.6 4541.3 16213.6 27431.9

Pantropical spotted dolphins 265.0 7.5 17149.5 149772.4 233427.8

Pygmy killer whales 7.3 0.7 547.3 4003.2 6603.0

Risso’s dolphins 10.4 1.5 562.0 6575.9 11790.6

Rough-toothed dolphins 11.6 0.9 899.9 7216.7 13211.7

Short-finned pilot whales 5.7 0.4 1099.4 4370.4 8747.7

Sperm whales 7.1 0.2 3487.8 9656.9 19792.6

Spinner dolphins 26.2 0.2 1658.9 20294.1 39876.9

Striped dolphins 18.1 0.8 1128.1 10740.9 18352.6
D-314 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-29. 2018 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 18.6 0.4 717.5 2947.3 4825.6

Beaked whales 10.4 0.4 631.7 13560.3 2735.9

Common bottlenose dolphins 68.6 5.4 1131.1 7210.2 10938.4

Bryde’s whales 0.1 3.2 6.5 38.7 40.2

Clymene dolphins 76.3 3.8 1277.4 6802.5 9775.5

False killer whales 18.1 0.7 419.2 1823.6 2806.2

Fraser’s dolphins 8.2 0.2 277.9 845.5 1050.0

Killer whales 0.8 0.0 37.8 96.6 112.5

Kogia 356.1 96.1 361.3 1002.8 1718.7

Melon-headed whales 39.8 1.0 1330.5 4285.6 5690.4

Pantropical spotted dolphins 509.3 28.7 8038.6 37652.8 49289.5

Pygmy killer whales 13.7 0.5 317.2 1311.5 1938.3

Risso’s dolphins 20.4 1.7 316.8 1631.9 2275.7

Rough-toothed dolphins 22.7 1.0 523.5 2368.3 3772.0

Short-finned pilot whales 9.7 0.3 330.1 1195.1 1788.4

Sperm whales 7.0 0.6 982.1 2726.3 4411.0

Spinner dolphins 45.8 2.0 791.6 5003.2 7910.6

Striped dolphins 32.8 1.7 534.2 2713.7 3776.2
Gulf of Mexico G&G Activities Programmatic EIS D-315

Table F-30. 2018 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 1.6 12.4 26.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 14.1 57.1 88.4

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.1 0.1

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.1 1.0 1.7

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-316 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-31. 2018 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-317

Table F-32. 2018 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.9 1.0 3.9 1.3

Beaked whales 0.0 0.1 0.1 4.1 0.0

Common bottlenose dolphins 0.0 10.4 13.4 27.1 7.7

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.2 0.1

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-318 Acoustic Propagation and Marine Mammal Exposure Modeling

F.2.4. 2019

Table F-33. 2019 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 5.3 0.1 278.9 3706.9 8628.9

Beaked whales 3.0 0.1 277.0 21037.3 4783.3

Common bottlenose dolphins 13.7 0.9 499.5 9273.0 21363.9

Bryde’s whales 0.0 0.5 3.6 56.8 68.5

Clymene dolphins 18.0 1.4 445.8 7927.3 15117.6

False killer whales 3.7 0.1 121.5 1890.8 3394.4

Fraser’s dolphins 1.9 0.0 147.7 1105.7 1811.4

Killer whales 0.2 0.0 17.0 117.7 171.2

Kogia 237.9 18.8 193.5 1381.8 3161.1

Melon-headed whales 9.7 0.2 698.5 5637.5 10006.1

Pantropical spotted dolphins 131.2 11.1 3174.7 48891.3 78810.7

Pygmy killer whales 2.9 0.1 92.1 1366.3 2286.9

Risso’s dolphins 5.3 0.6 132.4 2025.6 4020.0

Rough-toothed dolphins 4.6 0.2 152.4 2468.8 4677.2

Short-finned pilot whales 2.3 0.1 130.2 1269.2 2637.2

Sperm whales 1.7 0.1 362.3 2644.3 4916.0

Spinner dolphins 12.8 0.9 332.1 7283.4 16520.5

Striped dolphins 8.2 0.7 201.7 3405.1 6148.7
Gulf of Mexico G&G Activities Programmatic EIS D-319

Table F-34. 2019 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 360.2 37.5 51987.7 145156.3 192048.7

Beaked whales 26.0 1.2 2364.2 100180.1 25095.0

Common bottlenose dolphins 2513.7 139.3 302326.3 832539.5 1058082.9

Bryde’s whales 0.2 7.2 26.1 307.3 369.5

Clymene dolphins 194.7 15.6 3812.4 45827.6 85313.6

False killer whales 55.5 5.4 1317.1 11237.1 20096.9

Fraser’s dolphins 26.1 1.7 1093.4 6036.2 9991.7

Killer whales 2.4 0.3 134.2 617.0 898.6

Kogia 1253.7 277.0 1345.5 6982.0 15495.4

Melon-headed whales 124.2 8.7 4916.8 29368.5 52043.7

Pantropical spotted dolphins 1126.0 54.5 24137.8 251515.9 402878.2

Pygmy killer whales 40.8 3.7 871.8 7677.1 13240.5

Risso’s dolphins 50.8 7.1 1082.0 11204.0 20701.3

Rough-toothed dolphins 86.5 8.7 3806.3 21030.5 35439.8

Short-finned pilot whales 32.6 3.9 1178.1 8121.9 16564.8

Sperm whales 18.9 0.8 3487.9 17766.7 38593.6

Spinner dolphins 123.5 4.9 2455.8 34951.0 69804.6

Striped dolphins 78.3 4.8 1603.9 18273.9 32084.1
D-320 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-35. 2019 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 23.0 0.4 7216.1 20946.0 30581.8

Beaked whales 2.3 0.0 1232.9 32845.5 7811.7

Common bottlenose dolphins 108.7 4.3 40554.0 110805.1 179899.5

Bryde’s whales 0.0 0.5 14.9 96.3 110.9

Clymene dolphins 23.8 0.1 1586.7 15424.4 26555.0

False killer whales 6.0 0.5 471.0 3409.5 5700.4

Fraser’s dolphins 2.5 0.0 595.4 2005.5 2987.9

Killer whales 0.2 0.0 65.1 235.6 290.0

Kogia 1169.6 22.0 783.2 2434.9 5115.3

Melon-headed whales 12.3 0.0 2799.5 9992.7 16250.3

Pantropical spotted dolphins 165.5 0.4 11220.9 95897.8 145622.4

Pygmy killer whales 4.7 0.4 344.0 2445.2 3852.8

Risso’s dolphins 6.3 0.7 354.0 3957.5 6893.5

Rough-toothed dolphins 8.2 0.6 860.3 5093.7 8580.2

Short-finned pilot whales 2.6 0.0 535.7 2194.0 4242.7

Sperm whales 4.5 0.0 1899.3 5432.1 10919.1

Spinner dolphins 18.4 0.1 1196.3 14031.9 27709.5

Striped dolphins 10.7 0.0 715.8 6643.8 10972.3
Gulf of Mexico G&G Activities Programmatic EIS D-321

Table F-36. 2019 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 34.5 1.5 1848.0 4872.8 6049.0

Beaked whales 6.7 0.3 385.2 8066.9 1642.0

Common bottlenose dolphins 197.3 7.2 9384.0 24373.8 27267.1

Bryde’s whales 0.0 1.9 3.6 20.9 22.6

Clymene dolphins 46.3 2.6 742.1 3733.5 5321.4

False killer whales 11.3 0.4 265.4 1093.6 1662.0

Fraser’s dolphins 5.2 0.1 173.6 506.9 614.2

Killer whales 0.5 0.0 24.6 60.8 69.8

Kogia 228.1 62.9 232.2 628.9 1056.0

Melon-headed whales 25.0 0.6 824.1 2548.9 3351.0

Pantropical spotted dolphins 336.2 19.9 5209.2 23432.5 30390.4

Pygmy killer whales 8.6 0.3 197.5 789.1 1147.8

Risso’s dolphins 12.7 1.1 192.6 936.4 1308.4

Rough-toothed dolphins 15.3 0.7 425.4 1597.6 2410.7

Short-finned pilot whales 5.0 0.1 161.0 569.3 877.4

Sperm whales 3.8 0.3 499.4 1427.4 2277.9

Spinner dolphins 33.4 1.6 566.6 3356.2 5332.2

Striped dolphins 21.1 1.2 333.9 1613.4 2227.7
D-322 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-37. 2019 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 1.7 13.4 28.2

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 15.3 61.7 95.7

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.1 0.1

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.1 1.0 1.8

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-323

Table F-38. 2019 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.9 6.7 14.1

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 7.7 31.0 48.1

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.1

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.5 0.9

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-324 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-39. 2019 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.8 0.9 3.3 1.1

Beaked whales 0.0 0.1 0.1 4.1 0.0

Common bottlenose dolphins 0.0 9.3 12.0 24.1 6.8

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.2 0.1

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-325

F.2.5. 2020

Table F-40. 2020 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-326 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-41. 2020 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 257.3 21.5 33820.5 101931.8 143334.9

Beaked whales 32.0 1.2 2864.4 120588.4 30188.2

Common bottlenose dolphins 1689.3 64.7 195029.7 558752.9 730436.3

Bryde’s whales 0.2 8.6 31.1 364.5 439.5

Clymene dolphins 231.2 16.8 4583.2 54661.0 100979.0

False killer whales 66.4 5.9 1506.3 13247.4 23695.8

Fraser’s dolphins 31.0 1.9 1288.4 7165.0 11819.3

Killer whales 3.0 0.3 163.4 748.1 1083.6

Kogia 1526.0 336.4 1639.5 8489.6 18763.7

Melon-headed whales 149.4 9.6 5966.5 35476.4 62512.8

Pantropical spotted dolphins 1369.3 61.7 29494.0 305690.7 487609.9

Pygmy killer whales 49.4 4.1 1057.1 9252.6 15838.7

Risso’s dolphins 62.0 8.3 1305.4 13456.6 24789.6

Rough-toothed dolphins 93.7 8.7 3226.7 21288.3 37285.2

Short-finned pilot whales 37.8 4.1 1382.8 9487.1 19257.1

Sperm whales 22.8 0.9 4084.4 20970.2 45203.6

Spinner dolphins 153.7 6.0 3053.5 43120.3 86362.0

Striped dolphins 94.4 5.3 1949.4 22061.1 38529.1
Gulf of Mexico G&G Activities Programmatic EIS D-327

Table F-42. 2020 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 13.8 0.7 1695.3 11719.6 23546.6

Beaked whales 3.8 0.0 2074.1 56206.0 13558.4

Common bottlenose dolphins 31.1 0.0 1989.5 30571.2 59895.0

Bryde’s whales 0.0 0.8 24.3 165.0 193.0

Clymene dolphins 40.0 0.0 2643.0 26420.6 45219.4

False killer whales 10.0 0.8 754.2 5717.3 9609.3

Fraser’s dolphins 4.2 0.0 995.6 3364.5 5088.1

Killer whales 0.4 0.1 110.8 405.1 498.3

Kogia 1950.4 36.6 1320.6 4102.6 8796.0

Melon-headed whales 21.2 0.0 4738.5 16924.4 27954.2

Pantropical spotted dolphins 280.9 0.0 18917.1 164509.3 248462.5

Pygmy killer whales 7.9 0.7 580.5 4172.4 6575.2

Risso’s dolphins 10.4 1.2 581.6 6807.6 11735.1

Rough-toothed dolphins 12.1 0.9 932.4 7404.4 13091.1

Short-finned pilot whales 4.6 0.0 898.5 3695.9 7297.5

Sperm whales 8.0 0.0 3481.2 9698.1 20342.7

Spinner dolphins 30.6 0.0 1951.1 23989.5 47094.8

Striped dolphins 18.0 0.0 1197.9 11386.1 18696.1
D-328 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-43. 2020 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 19.4 0.3 737.0 3041.0 5110.1

Beaked whales 10.9 0.5 652.4 13921.0 2859.3

Common bottlenose dolphins 68.0 6.1 1145.4 7466.0 11361.6

Bryde’s whales 0.1 3.0 5.8 36.3 39.9

Clymene dolphins 76.8 4.1 1240.3 6528.2 9297.4

False killer whales 19.0 0.8 439.4 1862.6 2861.4

Fraser’s dolphins 8.7 0.2 287.8 863.6 1070.5

Killer whales 0.9 0.0 41.9 105.2 121.7

Kogia 381.1 102.2 385.8 1071.0 1860.2

Melon-headed whales 42.3 1.0 1377.3 4386.9 5898.9

Pantropical spotted dolphins 565.5 32.6 8800.1 40803.5 52942.7

Pygmy killer whales 14.5 0.6 337.3 1361.9 1991.7

Risso’s dolphins 21.3 1.9 315.6 1648.9 2295.0

Rough-toothed dolphins 23.7 1.0 544.5 2408.3 3848.4

Short-finned pilot whales 8.4 0.2 265.0 979.6 1548.0

Sperm whales 7.4 0.6 951.6 2668.1 4478.6

Spinner dolphins 53.9 2.3 929.8 5899.2 9344.3

Striped dolphins 35.2 1.9 560.3 2817.1 3888.4
Gulf of Mexico G&G Activities Programmatic EIS D-329

Table F-44. 2020 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.7 1.2 1.3

Beaked whales 0.0 0.0 0.0 34.8 1.8

Common bottlenose dolphins 0.0 0.0 2.0 3.5 4.4

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 1.0 2.9 3.4

False killer whales 0.0 0.0 0.2 0.7 0.9

Fraser’s dolphins 0.0 0.0 0.2 0.4 0.6

Killer whales 0.0 0.0 0.0 0.1 0.1

Kogia 0.1 0.0 0.3 0.5 0.9

Melon-headed whales 0.0 0.0 1.1 2.0 3.1

Pantropical spotted dolphins 0.0 0.0 6.1 20.0 25.3

Pygmy killer whales 0.0 0.0 0.1 0.5 0.7

Risso’s dolphins 0.0 0.0 0.2 0.7 1.1

Rough-toothed dolphins 0.0 0.0 0.2 0.8 1.2

Short-finned pilot whales 0.0 0.0 0.6 0.4 0.7

Sperm whales 0.0 0.0 0.4 2.1 4.6

Spinner dolphins 0.0 0.0 1.0 2.3 2.3

Striped dolphins 0.0 0.0 0.4 1.3 1.6
D-330 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-45. 2020 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.5 0.8 0.9

Beaked whales 0.0 0.0 0.0 23.2 1.2

Common bottlenose dolphins 0.0 0.0 1.3 2.3 2.9

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.7 1.9 2.3

False killer whales 0.0 0.0 0.1 0.4 0.6

Fraser’s dolphins 0.0 0.0 0.2 0.3 0.4

Killer whales 0.0 0.0 0.0 0.0 0.1

Kogia 0.1 0.0 0.2 0.4 0.6

Melon-headed whales 0.0 0.0 0.7 1.3 2.0

Pantropical spotted dolphins 0.0 0.0 4.1 13.3 16.8

Pygmy killer whales 0.0 0.0 0.1 0.3 0.5

Risso’s dolphins 0.0 0.0 0.1 0.5 0.8

Rough-toothed dolphins 0.0 0.0 0.2 0.6 0.8

Short-finned pilot whales 0.0 0.0 0.1 0.3 0.4

Sperm whales 0.0 0.0 0.3 1.4 3.1

Spinner dolphins 0.0 0.0 0.6 1.5 1.5

Striped dolphins 0.0 0.0 0.3 0.9 1.0
Gulf of Mexico G&G Activities Programmatic EIS D-331

Table F-46. 2020 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.9 1.0 3.8 1.3

Beaked whales 0.0 0.1 0.1 3.9 0.0

Common bottlenose dolphins 0.0 11.0 14.2 28.2 7.8

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.2 0.1

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-332 Acoustic Propagation and Marine Mammal Exposure Modeling

F.2.6. 2021

Table F-47. 2021 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-333

Table F-48. 2021 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 347.6 31.8 49489.2 140536.8 188872.3

Beaked whales 32.7 2.1 2764.9 119940.7 29899.4

Common bottlenose dolphins 2418.9 92.0 290228.9 806443.3 1031848.6

Bryde’s whales 0.2 9.2 33.4 385.0 455.9

Clymene dolphins 248.7 25.7 4658.0 56176.1 108238.1

False killer whales 66.3 8.0 1537.5 13316.3 24469.9

Fraser’s dolphins 30.9 2.4 1274.5 7165.3 12086.8

Killer whales 2.8 0.3 152.7 709.2 1057.1

Kogia 1478.7 327.3 1561.8 8167.6 18140.7

Melon-headed whales 147.6 12.4 5797.4 34974.8 62700.4

Pantropical spotted dolphins 1322.3 79.8 27700.2 289268.8 474920.2

Pygmy killer whales 48.4 5.4 1030.9 9113.0 16156.0

Risso’s dolphins 61.7 9.0 1291.4 13311.6 25268.3

Rough-toothed dolphins 99.4 12.0 3943.0 23384.3 40799.8

Short-finned pilot whales 43.6 6.3 1551.5 10762.0 22089.1

Sperm whales 22.3 1.5 4263.5 21421.5 45647.3

Spinner dolphins 137.8 5.9 2719.4 38024.9 76430.6

Striped dolphins 95.1 7.5 1885.3 21514.8 38867.0
D-334 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-49. 2021 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 28.4 1.1 7861.1 25280.4 39499.1

Beaked whales 4.0 0.1 2001.4 54098.4 12955.0

Common bottlenose dolphins 119.5 5.1 41279.1 121928.8 202568.4

Bryde’s whales 0.0 0.9 26.8 173.5 197.1

Clymene dolphins 44.8 3.2 2668.0 26639.5 48248.8

False killer whales 9.6 0.8 744.0 5605.3 9785.0

Fraser’s dolphins 4.2 0.1 962.3 3263.5 5113.4

Killer whales 0.4 0.1 100.0 370.4 474.1

Kogia 1824.5 34.0 1230.4 3813.5 8232.2

Melon-headed whales 20.7 0.6 4541.4 16213.9 27432.3

Pantropical spotted dolphins 265.0 7.5 17151.2 149776.5 233432.8

Pygmy killer whales 7.3 0.7 547.3 4003.3 6603.2

Risso’s dolphins 10.4 1.5 562.7 6577.7 11792.8

Rough-toothed dolphins 12.6 1.0 1202.8 7959.4 14110.5

Short-finned pilot whales 5.7 0.4 1099.4 4370.4 8747.7

Sperm whales 7.1 0.2 3487.8 9656.9 19792.6

Spinner dolphins 26.2 0.2 1658.9 20294.1 39876.9

Striped dolphins 18.1 0.8 1128.1 10740.9 18352.7
Gulf of Mexico G&G Activities Programmatic EIS D-335

Table F-50. 2021 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 41.1 1.6 2122.9 6085.2 7990.8

Beaked whales 10.4 0.4 631.7 13560.3 2735.9

Common bottlenose dolphins 224.7 9.0 9800.1 27345.3 31706.3

Bryde’s whales 0.1 3.2 6.5 38.7 40.2

Clymene dolphins 76.3 3.8 1277.4 6802.5 9775.5

False killer whales 18.2 0.7 426.9 1838.4 2820.4

Fraser’s dolphins 8.3 0.2 280.1 850.7 1055.3

Killer whales 0.8 0.0 37.8 96.7 112.6

Kogia 356.2 96.2 361.5 1003.1 1719.1

Melon-headed whales 39.8 1.0 1330.5 4285.7 5690.4

Pantropical spotted dolphins 509.3 28.7 8039.0 37653.7 49290.4

Pygmy killer whales 13.7 0.5 317.2 1311.5 1938.3

Risso’s dolphins 20.4 1.7 317.0 1632.3 2276.1

Rough-toothed dolphins 24.0 1.0 628.9 2571.4 3967.8

Short-finned pilot whales 9.7 0.3 330.1 1195.1 1788.4

Sperm whales 7.0 0.6 982.1 2726.3 4411.0

Spinner dolphins 45.8 2.0 791.6 5003.2 7910.6

Striped dolphins 32.8 1.7 534.2 2713.7 3776.2
D-336 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-51. 2021 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-337

Table F-52. 2021 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-338 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-53. 2021 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.8 0.9 3.3 1.1

Beaked whales 0.0 0.1 0.1 4.6 0.0

Common bottlenose dolphins 0.0 9.8 12.6 24.7 6.7

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.2 0.1

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.1 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-339

F.2.7. 2022

Table F-54. 2022 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 3.5 0.1 180.6 2520.4 5817.3

Beaked whales 1.9 0.1 185.1 14314.5 3282.3

Common bottlenose dolphins 8.7 0.6 348.9 6389.2 14166.9

Bryde’s whales 0.0 0.4 2.4 38.7 46.9

Clymene dolphins 12.1 0.9 299.9 5445.1 10128.0

False killer whales 2.6 0.1 80.9 1286.2 2280.7

Fraser’s dolphins 1.2 0.0 98.4 746.2 1238.2

Killer whales 0.1 0.0 11.6 80.7 116.5

Kogia 157.3 12.4 127.2 930.9 2160.5

Melon-headed whales 6.2 0.1 462.2 3796.5 6839.3

Pantropical spotted dolphins 88.9 7.5 2149.3 33554.6 52949.7

Pygmy killer whales 2.0 0.0 61.6 930.2 1538.5

Risso’s dolphins 3.3 0.4 87.5 1395.5 2694.7

Rough-toothed dolphins 3.2 0.1 100.9 1678.2 3139.7

Short-finned pilot whales 1.4 0.0 84.5 850.7 1802.3

Sperm whales 1.2 0.1 262.9 1920.0 3895.3

Spinner dolphins 8.5 0.5 220.8 5007.9 11040.3

Striped dolphins 5.5 0.4 136.0 2338.2 4122.9
D-340 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-55. 2022 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 268.1 28.5 36347.7 106098.2 145899.1

Beaked whales 26.0 1.2 2364.2 100180.1 25094.9

Common bottlenose dolphins 1788.4 119.4 207103.8 583275.6 755337.1

Bryde’s whales 0.2 7.2 26.1 307.3 369.5

Clymene dolphins 194.7 15.6 3812.4 45827.6 85313.6

False killer whales 55.1 5.4 1267.0 11078.4 19909.7

Fraser’s dolphins 25.8 1.7 1071.8 5968.8 9905.8

Killer whales 2.4 0.3 133.9 616.1 897.5

Kogia 1253.3 276.6 1344.1 6978.2 15490.0

Melon-headed whales 124.2 8.7 4916.5 29367.7 52042.6

Pantropical spotted dolphins 1126.0 54.5 24134.2 251504.8 402863.9

Pygmy killer whales 40.8 3.7 871.7 7676.6 13240.0

Risso’s dolphins 50.8 7.1 1080.1 11199.1 20695.0

Rough-toothed dolphins 80.7 8.2 3076.6 18851.2 32666.3

Short-finned pilot whales 32.6 3.9 1178.1 8121.9 16564.8

Sperm whales 18.9 0.8 3487.9 17766.7 38593.6

Spinner dolphins 123.5 4.9 2455.8 34951.0 69804.6

Striped dolphins 78.3 4.8 1603.8 18273.8 32084.0
Gulf of Mexico G&G Activities Programmatic EIS D-341

Table F-56. 2022 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 12.3 0.7 1586.3 10771.9 21642.0

Beaked whales 3.6 0.0 1924.3 51580.8 12331.2

Common bottlenose dolphins 29.1 0.0 1890.8 28040.3 55364.6

Bryde’s whales 0.0 0.8 23.1 151.3 175.3

Clymene dolphins 37.1 0.1 2467.6 24231.2 41628.1

False killer whales 9.3 0.8 700.4 5261.2 8838.1

Fraser’s dolphins 3.9 0.0 918.1 3103.3 4653.5

Killer whales 0.4 0.1 101.9 370.3 455.7

Kogia 1819.3 34.1 1222.9 3801.1 8045.4

Melon-headed whales 19.4 0.0 4378.9 15633.9 25568.0

Pantropical spotted dolphins 259.2 0.4 17524.9 150730.2 228438.3

Pygmy killer whales 7.3 0.7 537.4 3835.8 6044.4

Risso’s dolphins 9.8 1.1 547.2 6224.9 10803.0

Rough-toothed dolphins 11.3 0.8 868.1 6819.1 12045.1

Short-finned pilot whales 4.2 0.0 835.2 3426.0 6675.2

Sperm whales 7.1 0.0 3059.7 8664.8 17700.0

Spinner dolphins 28.6 0.1 1846.7 22028.4 43407.8

Striped dolphins 16.7 0.0 1115.1 10439.1 17204.3
D-342 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-57. 2022 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 18.5 0.4 688.1 2748.5 4587.1

Beaked whales 10.3 0.4 602.7 12707.2 2595.1

Common bottlenose dolphins 63.8 5.6 1096.8 6727.3 10286.4

Bryde’s whales 0.1 2.9 5.5 33.0 35.8

Clymene dolphins 72.0 3.9 1155.6 5909.5 8420.5

False killer whales 17.6 0.7 404.2 1699.6 2601.6

Fraser’s dolphins 8.0 0.2 267.3 789.6 965.7

Killer whales 0.8 0.0 38.5 95.8 110.3

Kogia 355.1 96.8 360.6 985.6 1675.8

Melon-headed whales 39.1 1.0 1283.2 4011.1 5317.2

Pantropical spotted dolphins 524.7 30.8 8142.2 37032.7 48037.0

Pygmy killer whales 13.4 0.5 309.9 1243.0 1811.7

Risso’s dolphins 19.8 1.8 297.6 1485.6 2073.0

Rough-toothed dolphins 21.9 0.9 501.5 2197.3 3497.6

Short-finned pilot whales 7.8 0.2 249.3 895.8 1393.4

Sperm whales 6.3 0.5 816.6 2316.8 3770.7

Spinner dolphins 51.4 2.4 876.5 5322.6 8447.0

Striped dolphins 32.8 1.8 520.6 2552.4 3523.8
Gulf of Mexico G&G Activities Programmatic EIS D-343

Table F-58. 2022 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-344 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-59. 2022 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-345

Table F-60. 2022 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.7 0.8 3.0 1.0

Beaked whales 0.0 0.1 0.1 5.0 0.0

Common bottlenose dolphins 0.0 8.7 11.1 22.0 6.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.1 0.1 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.1 0.1

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.1 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-346 Acoustic Propagation and Marine Mammal Exposure Modeling

F.2.8. 2023

Table F-61. 2023 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 1.2 0.0 60.2 840.1 1939.1

Beaked whales 0.6 0.0 61.7 4771.5 1094.1

Common bottlenose dolphins 2.9 0.2 116.3 2129.7 4722.3

Bryde’s whales 0.0 0.1 0.8 12.9 15.6

Clymene dolphins 4.0 0.3 100.0 1815.0 3376.0

False killer whales 0.9 0.0 27.0 428.7 760.2

Fraser’s dolphins 0.4 0.0 32.8 248.7 412.7

Killer whales 0.0 0.0 3.9 26.9 38.8

Kogia 52.4 4.1 42.4 310.3 720.2

Melon-headed whales 2.1 0.0 154.1 1265.5 2279.8

Pantropical spotted dolphins 29.6 2.5 716.4 11184.9 17649.9

Pygmy killer whales 0.7 0.0 20.5 310.1 512.8

Risso’s dolphins 1.1 0.1 29.2 465.2 898.2

Rough-toothed dolphins 1.1 0.0 33.6 559.4 1046.6

Short-finned pilot whales 0.5 0.0 28.2 283.6 600.8

Sperm whales 0.4 0.0 87.6 640.0 1298.4

Spinner dolphins 2.8 0.2 73.6 1669.3 3680.1

Striped dolphins 1.8 0.1 45.3 779.4 1374.3
Gulf of Mexico G&G Activities Programmatic EIS D-347

Table F-62. 2023 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 336.5 30.1 49020.7 136922.4 180782.4

Beaked whales 26.0 1.2 2364.2 100180.1 25095.0

Common bottlenose dolphins 2371.9 81.9 289426.7 797721.2 1011713.9

Bryde’s whales 0.2 7.2 26.1 307.2 369.5

Clymene dolphins 194.7 15.6 3812.4 45827.6 85313.6

False killer whales 55.5 5.4 1311.9 11223.3 20077.8

Fraser’s dolphins 26.1 1.7 1091.6 6030.3 9983.3

Killer whales 2.4 0.3 134.1 616.8 898.3

Kogia 1253.7 277.0 1345.4 6981.9 15495.1

Melon-headed whales 124.2 8.7 4916.8 29368.5 52043.6

Pantropical spotted dolphins 1126.0 54.5 24137.6 251515.4 402877.4

Pygmy killer whales 40.8 3.7 871.8 7677.0 13240.4

Risso’s dolphins 50.8 7.1 1081.8 11203.7 20700.8

Rough-toothed dolphins 85.4 8.4 3649.9 20615.6 34867.5

Short-finned pilot whales 32.6 3.9 1178.1 8121.9 16564.8

Sperm whales 18.9 0.8 3487.9 17766.7 38593.6

Spinner dolphins 123.5 4.9 2455.8 34951.0 69804.6

Striped dolphins 78.3 4.8 1603.9 18273.9 32084.1
D-348 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-63. 2023 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 24.4 0.5 7325.1 21893.7 32486.3

Beaked whales 2.5 0.0 1382.7 37470.7 9039.0

Common bottlenose dolphins 110.7 4.3 40652.8 113336.0 184429.8

Bryde’s whales 0.0 0.6 16.2 110.0 128.7

Clymene dolphins 26.7 0.0 1762.0 17613.7 30146.3

False killer whales 6.7 0.6 524.9 3865.6 6471.6

Fraser’s dolphins 2.9 0.0 672.9 2266.7 3422.5

Killer whales 0.3 0.0 74.0 270.4 332.6

Kogia 1300.7 24.4 881.0 2736.4 5865.9

Melon-headed whales 14.2 0.0 3159.1 11283.2 18636.5

Pantropical spotted dolphins 187.3 0.0 12613.1 109677.0 165646.7

Pygmy killer whales 5.2 0.5 387.0 2781.7 4383.7

Risso’s dolphins 6.9 0.8 388.5 4540.2 7825.6

Rough-toothed dolphins 9.0 0.7 924.5 5679.0 9626.2

Short-finned pilot whales 3.0 0.0 599.0 2464.0 4865.0

Sperm whales 5.3 0.0 2320.8 6465.4 13561.8

Spinner dolphins 20.4 0.0 1300.7 15993.0 31396.5

Striped dolphins 12.0 0.0 798.6 7590.8 12464.1
Gulf of Mexico G&G Activities Programmatic EIS D-349

Table F-64. 2023 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species

Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 35.4 1.4 1896.8 5165.2 6572.0

Beaked whales 7.3 0.3 434.9 9280.7 1906.2

Common bottlenose dolphins 201.4 7.7 9432.6 25112.5 28342.2

Bryde’s whales 0.1 2.0 3.9 24.2 26.6

Clymene dolphins 51.2 2.7 826.9 4352.2 6198.3

False killer whales 12.8 0.5 300.6 1256.5 1921.9

Fraser’s dolphins 5.9 0.1 194.2 580.9 719.0

Killer whales 0.6 0.0 28.0 70.2 81.2

Kogia 254.2 68.2 257.3 714.3 1240.4

Melon-headed whales 28.2 0.7 918.2 2924.6 3932.6

Pantropical spotted dolphins 377.0 21.7 5867.1 27203.2 35296.1

Pygmy killer whales 9.7 0.4 224.9 908.0 1327.8

Risso’s dolphins 14.2 1.3 210.6 1099.7 1530.4

Rough-toothed dolphins 17.0 0.8 468.4 1808.7 2761.5

Short-finned pilot whales 5.6 0.2 176.7 653.0 1032.0

Sperm whales 4.9 0.4 634.4 1778.7 2985.7

Spinner dolphins 35.9 1.6 619.8 3932.8 6229.5

Striped dolphins 23.5 1.3 373.5 1878.1 2592.3
D-350 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-65. 2023 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-351

Table F-66. 2023 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-352 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-67. 2023 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.7 0.8 3.0 1.0

Beaked whales 0.0 0.1 0.1 5.3 0.0

Common bottlenose dolphins 0.0 8.7 11.1 22.0 6.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.1 0.1 0.1 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.1 0.1

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.1 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-353

F.2.9. 2024

Table F-68. 2024 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-354 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-69. 2024 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 236.1 20.9 33109.3 95093.0 128778.3

Beaked whales 23.0 1.2 2026.6 86451.3 21614.1

Common bottlenose dolphins 1622.5 60.1 193716.6 541343.9 694790.8

Bryde’s whales 0.2 6.4 23.0 268.6 321.4

Clymene dolphins 171.5 14.9 3313.3 39792.5 74885.7

False killer whales 47.7 5.0 1103.2 9583.5 17325.0

Fraser’s dolphins 22.3 1.5 925.9 5163.3 8601.5

Killer whales 2.1 0.2 114.0 525.6 770.7

Kogia 1079.3 238.4 1151.9 5991.1 13285.1

Melon-headed whales 106.9 7.8 4228.9 25319.1 44988.0

Pantropical spotted dolphins 967.6 50.1 20600.8 214510.8 346237.1

Pygmy killer whales 35.2 3.4 750.4 6606.7 11486.2

Risso’s dolphins 44.3 6.2 933.0 9635.2 17965.1

Rough-toothed dolphins 70.5 7.4 2723.1 16501.8 28596.1

Short-finned pilot whales 29.0 3.7 1046.7 7224.5 14753.3

Sperm whales 16.2 0.8 3010.7 15290.3 32914.3

Spinner dolphins 104.9 4.2 2080.4 29364.5 58821.9

Striped dolphins 67.9 4.5 1378.6 15686.9 27788.5
Gulf of Mexico G&G Activities Programmatic EIS D-355

Table F-70. 2024 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 13.8 0.7 1695.3 11719.6 23546.6

Beaked whales 3.8 0.0 2074.1 56206.0 13558.4

Common bottlenose dolphins 31.1 0.0 1989.5 30571.2 59895.0

Bryde’s whales 0.0 0.8 24.3 165.0 193.0

Clymene dolphins 40.0 0.0 2643.0 26420.6 45219.4

False killer whales 10.0 0.8 754.2 5717.3 9609.3

Fraser’s dolphins 4.2 0.0 995.6 3364.5 5088.1

Killer whales 0.4 0.1 110.8 405.1 498.3

Kogia 1950.4 36.6 1320.6 4102.6 8796.0

Melon-headed whales 21.2 0.0 4738.5 16924.4 27954.2

Pantropical spotted dolphins 280.9 0.0 18917.1 164509.3 248462.5

Pygmy killer whales 7.9 0.7 580.5 4172.4 6575.2

Risso’s dolphins 10.4 1.2 581.6 6807.6 11735.1

Rough-toothed dolphins 12.1 0.9 932.4 7404.4 13091.1

Short-finned pilot whales 4.6 0.0 898.5 3695.9 7297.5

Sperm whales 8.0 0.0 3481.2 9698.1 20342.7

Spinner dolphins 30.6 0.0 1951.1 23989.5 47094.8

Striped dolphins 18.0 0.0 1197.9 11386.1 18696.1
D-356 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-71. 2024 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 19.4 0.3 737.0 3041.0 5110.1

Beaked whales 10.9 0.5 652.4 13921.0 2859.3

Common bottlenose dolphins 68.0 6.1 1145.4 7466.0 11361.6

Bryde’s whales 0.1 3.0 5.8 36.3 39.9

Clymene dolphins 76.8 4.1 1240.3 6528.2 9297.4

False killer whales 19.0 0.8 439.4 1862.6 2861.4

Fraser’s dolphins 8.7 0.2 287.8 863.6 1070.5

Killer whales 0.9 0.0 41.9 105.2 121.7

Kogia 381.1 102.2 385.8 1071.0 1860.2

Melon-headed whales 42.3 1.0 1377.3 4386.9 5898.9

Pantropical spotted dolphins 565.5 32.6 8800.1 40803.5 52942.7

Pygmy killer whales 14.5 0.6 337.3 1361.9 1991.7

Risso’s dolphins 21.3 1.9 315.6 1648.9 2295.0

Rough-toothed dolphins 23.7 1.0 544.5 2408.3 3848.4

Short-finned pilot whales 8.4 0.2 265.0 979.6 1548.0

Sperm whales 7.4 0.6 951.6 2668.1 4478.6

Spinner dolphins 53.9 2.3 929.8 5899.2 9344.3

Striped dolphins 35.2 1.9 560.3 2817.1 3888.4
Gulf of Mexico G&G Activities Programmatic EIS D-357

Table F-72. 2024 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-358 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-73. 2024 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-359

Table F-74. 2024 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.7 0.8 3.0 1.0

Beaked whales 0.0 0.1 0.1 5.3 0.0

Common bottlenose dolphins 0.0 8.7 11.1 22.0 6.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.1 0.1 0.1 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.1 0.1

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.1 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-360 Acoustic Propagation and Marine Mammal Exposure Modeling

F.2.10. 2025

Table F-75. 2025 annual exposure estimate totals for 2-D survey (8000 in3 airgun array, 1 vessel).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.3 0.0 16.4 197.8 468.6

Beaked whales 0.2 0.0 15.3 1120.5 250.2

Common bottlenose dolphins 0.8 0.1 25.1 480.6 1199.5

Bryde’s whales 0.0 0.0 0.2 3.0 3.6

Clymene dolphins 1.0 0.1 24.3 413.7 831.6

False killer whales 0.2 0.0 6.8 100.8 185.6

Fraser’s dolphins 0.1 0.0 8.2 59.9 95.5

Killer whales 0.0 0.0 0.9 6.2 9.1

Kogia 13.4 1.1 11.0 75.1 166.8

Melon-headed whales 0.6 0.0 39.4 306.8 527.8

Pantropical spotted dolphins 7.1 0.6 170.9 2556.1 4310.2

Pygmy killer whales 0.1 0.0 5.1 72.7 124.7

Risso’s dolphins 0.3 0.0 7.5 105.0 220.9

Rough-toothed dolphins 0.2 0.0 8.6 131.8 256.2

Short-finned pilot whales 0.1 0.0 7.6 69.8 139.2

Sperm whales 0.1 0.0 16.6 120.7 170.1

Spinner dolphins 0.7 0.1 18.5 379.3 913.4

Striped dolphins 0.4 0.0 10.9 177.8 337.6
Gulf of Mexico G&G Activities Programmatic EIS D-361

Table F-76. 2025 annual exposure estimate totals for 3-D NAZ survey (8000 in3 airgun array, 2 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 351.8 37.2 51716.5 142385.1 186194.2

Beaked whales 23.0 1.2 2026.6 86451.4 21614.1

Common bottlenose dolphins 2489.5 137.4 301838.7 825426.1 1043905.6

Bryde’s whales 0.2 6.4 23.0 268.6 321.4

Clymene dolphins 171.5 14.9 3313.3 39792.5 74885.7

False killer whales 48.2 5.0 1158.6 9756.0 17531.3

Fraser’s dolphins 22.5 1.5 949.3 5236.5 8695.8

Killer whales 2.1 0.2 114.4 526.7 772.1

Kogia 1079.7 238.9 1153.3 5995.0 13290.8

Melon-headed whales 106.9 7.8 4229.2 25320.0 44989.1

Pantropical spotted dolphins 967.7 50.1 20604.6 214522.5 346252.3

Pygmy killer whales 35.2 3.4 750.6 6607.1 11486.8

Risso’s dolphins 44.3 6.2 935.0 9640.5 17971.8

Rough-toothed dolphins 77.4 8.2 3609.2 19096.1 31941.8

Short-finned pilot whales 29.0 3.7 1046.8 7224.6 14753.3

Sperm whales 16.2 0.8 3010.7 15290.3 32914.3

Spinner dolphins 104.9 4.2 2080.4 29364.5 58821.9

Striped dolphins 67.9 4.5 1378.6 15687.0 27788.7
D-362 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-77. 2025 annual exposure estimate totals for 3-D WAZ survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 26.7 0.6 7607.6 23846.9 36410.8

Beaked whales 3.2 0.0 1728.4 46838.4 11298.7

Common bottlenose dolphins 115.9 4.3 40984.4 118431.2 194412.3

Bryde’s whales 0.0 0.7 20.3 137.5 160.9

Clymene dolphins 33.4 0.0 2202.5 22017.2 37682.9

False killer whales 8.4 0.7 650.6 4818.5 8073.2

Fraser’s dolphins 3.6 0.0 838.8 2827.5 4270.5

Killer whales 0.4 0.1 92.5 337.9 415.6

Kogia 1625.7 30.5 1101.1 3420.2 7331.9

Melon-headed whales 17.7 0.0 3948.8 14104.0 23295.6

Pantropical spotted dolphins 234.1 0.0 15765.9 137095.2 207057.2

Pygmy killer whales 6.5 0.6 483.8 3477.1 5479.5

Risso’s dolphins 8.7 1.0 485.5 5674.8 9781.5

Rough-toothed dolphins 11.0 0.8 1079.9 6913.0 11808.0

Short-finned pilot whales 3.8 0.0 748.8 3080.0 6081.3

Sperm whales 6.7 0.0 2901.0 8081.8 16952.3

Spinner dolphins 25.5 0.0 1625.9 19991.3 39245.7

Striped dolphins 15.0 0.0 998.2 9488.5 15580.1
Gulf of Mexico G&G Activities Programmatic EIS D-363

Table F-78. 2025 annual exposure estimate totals for Coil survey (8000 in3 airgun array, 4 vessels).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 38.7 1.4 2019.7 5672.1 7423.7

Beaked whales 9.1 0.4 543.7 11600.8 2382.8

Common bottlenose dolphins 212.8 8.8 9623.5 26356.8 30235.8

Bryde’s whales 0.1 2.5 4.8 30.2 33.2

Clymene dolphins 64.0 3.4 1033.6 5440.2 7747.8

False killer whales 15.9 0.7 373.8 1566.9 2398.8

Fraser’s dolphins 7.3 0.2 242.1 724.9 897.4

Killer whales 0.8 0.0 35.0 87.7 101.5

Kogia 317.7 85.3 321.6 892.8 1550.5

Melon-headed whales 35.3 0.8 1147.7 3655.8 4915.8

Pantropical spotted dolphins 471.3 27.2 7333.7 34003.8 44119.9

Pygmy killer whales 12.1 0.5 281.1 1135.0 1659.7

Risso’s dolphins 17.8 1.6 263.2 1374.5 1912.9

Rough-toothed dolphins 21.0 0.9 559.1 2210.0 3402.9

Short-finned pilot whales 7.0 0.2 220.9 816.3 1290.0

Sperm whales 6.1 0.5 793.0 2223.4 3732.1

Spinner dolphins 44.9 2.0 774.8 4916.0 7786.9

Striped dolphins 29.3 1.6 466.9 2347.6 3240.4
D-364 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-79. 2025 annual exposure estimate totals for 90 in3 airgun.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
Gulf of Mexico G&G Activities Programmatic EIS D-365

Table F-80. 2025 annual exposure estimate totals for boomer.

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.0 0.0 0.0 0.0

Beaked whales 0.0 0.0 0.0 0.0 0.0

Common bottlenose dolphins 0.0 0.0 0.0 0.0 0.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.0 0.0 0.0 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.0 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.0 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0
D-366 Acoustic Propagation and Marine Mammal Exposure Modeling

Table F-81. 2025 annual exposure estimate totals for side-scan sonar, sub-bottom profiler, and multibeam scanner).

Species Number of Level A exposures Number of Level B exposures

peak SPL SEL 180 rms SPL Step fxn 160 rms SPL

Atlantic spotted dolphins 0.0 0.6 0.7 2.4 0.8

Beaked whales 0.0 0.1 0.1 5.6 0.0

Common bottlenose dolphins 0.0 7.0 9.0 17.9 5.0

Bryde’s whales 0.0 0.0 0.0 0.0 0.0

Clymene dolphins 0.0 0.0 0.0 0.0 0.0

False killer whales 0.0 0.0 0.0 0.0 0.0

Fraser’s dolphins 0.0 0.0 0.0 0.0 0.0

Killer whales 0.0 0.0 0.0 0.0 0.0

Kogia 0.0 0.0 0.0 0.0 0.0

Melon-headed whales 0.0 0.0 0.0 0.0 0.0

Pantropical spotted dolphins 0.0 0.1 0.1 0.1 0.0

Pygmy killer whales 0.0 0.0 0.0 0.0 0.0

Risso’s dolphins 0.0 0.0 0.0 0.0 0.0

Rough-toothed dolphins 0.0 0.0 0.0 0.1 0.0

Short-finned pilot whales 0.0 0.0 0.0 0.0 0.0

Sperm whales 0.0 0.0 0.0 0.1 0.0

Spinner dolphins 0.0 0.0 0.0 0.0 0.0

Striped dolphins 0.0 0.0 0.0 0.0 0.0

The Department of the Interior Mission

The Department of the Interior protects and manages the Nation’s natural 

resources and cultural heritage; provides scientific and other information 

about those resources; and honors the Nation’s trust responsibilities or 

special commitments to American Indians, Alaska Natives, and affiliated 

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The Bureau of Ocean Energy Management (BOEM) is responsible for 

managing development of U.S. Outer Continental Shelf energy and mineral 

resources in an environmentally and economically responsible way.