61530 Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Notices 

hearings to solicit public comments on 

Joint Amendment with the Gulf and 

South Atlantic Council’s to Address 

Electronic Reporting for Commercial 

Vessels participating in the coastal 

logbook program. 

DATES: The public hearings will take 

place Monday, September 18, 2023 at 10 

a.m., EDT and Tuesday, September 19,

2023 at 6 p.m., EDT and will conclude

no later than 3 hours after the start time

of each webinar. For specific dates and

times, see SUPPLEMENTARY INFORMATION.

Written public comments must be

received on or before 5 p.m. EDT on

October 17, 2023.

ADDRESSES: Please visit the Gulf Council 

website at www.gulfcouncil.org for 

meeting materials and webinar 

registration information. If you prefer to 

‘‘listen in’’, you may access the log-on 

information by visiting our website at 

www.gulfcouncil.org. 

Meeting addresses: The public 

hearings will be held virtual/webinars. 

For specific locations, see 

SUPPLEMENTARY INFORMATION. 

Public comments: Comments may be 

submitted online through the Council’s 

public portal by visiting 

www.gulfcouncil.org and clicking on 

‘‘CONTACT US’’. 

FOR FURTHER INFORMATION CONTACT: 

Emily Muehlstein; Public Information 

Officer; emily.muehlstein@

gulfcouncil.org, Gulf of Mexico Fishery 

Management Council; telephone: (813) 

348–1630. 

SUPPLEMENTARY INFORMATION: The 

original notice published in the Federal 

Register on July 31, 2023 (88 FR 49451). 

The hearings were scheduled for August 

29th and 30th. The hearing dates had to 

be changed due to a hurricane. 

The agenda for the following three 

webinar public hearings are as follows: 

Council and NOAA staff will begin with 

a presentation on the proposed 

management change addressed in the 

Amendment Addressing Electronic 

Reporting for Commercial Vessels. The 

Gulf and South Atlantic Councils are 

currently considering requiring federal 

commercial permit holders to submit 

commercial coastal logbooks 

electronically, rather than mailing paper 

logbooks. This amendment would 

impact commercial Reef Fish and 

Coastal Migratory Pelagic permit 

holders in the Gulf of Mexico and 

commercial Snapper/Grouper and 

Dolphin/Wahoo permit holders in the 

South Atlantic. 

Staff and a Council member will be 

available to answer any questions, and 

the public will have the opportunity to 

provide testimony on the amendment 

and other related testimony at the end 

of each public hearing webinar. 

Webinars: 

Tuesday, September 18, 2023; webinar 

to begin at 10 a.m., EDT. 

Wednesday, September 19, 2023; 

webinar to begin at 6 p.m., EDT. 

Visit www.gulfcouncil.org website and 

click on the ‘‘meetings’’ tab for 

registration information. After 

registering, you will receive a 

confirmation email containing 

information about joining the webinar. 

Authority: 16 U.S.C. 1801 et seq. 

Dated: August 31, 2023. 

Rey Israel Marquez, 

Acting Deputy Director, Office of Sustainable 

Fisheries, National Marine Fisheries Service. 

[FR Doc. 2023–19270 Filed 9–6–23; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD182] 

Takes of Marine Mammals Incidental to 

Specified Activities; Taking Marine 

Mammals Incidental to Columbia East 

Lateral XPRESS Project 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed incidental 

harassment authorization; request for 

comments on proposed authorization 

and possible renewal. 

SUMMARY: NMFS has received a request 

from TC Energy Columbia Gulf 

Transmission, LLC for authorization to 

take marine mammals incidental to the 

East Lateral XPRESS Project in Barataria 

Bay, Louisiana. Pursuant to the Marine 

Mammal Protection Act (MMPA), NMFS 

is requesting comments on its proposal 

to issue an incidental harassment 

authorization (IHA) to incidentally take 

marine mammals during the specified 

activities. NMFS is also requesting 

comments on a possible one-time, oneyear renewal that could be issued under 

certain circumstances and if all 

requirements are met, as described in 

Request for Public Comments at the end 

of this notice. NMFS will consider 

public comments prior to making any 

final decision on the issuance of the 

requested MMPA authorization and 

agency responses will be summarized in 

the final notice of our decision. 

DATES: Comments and information must 

be received no later than October 10, 

2023. 

ADDRESSES: Comments should be 

addressed to Jolie Harrison, Chief, 

Permits and Conservation Division, 

Office of Protected Resources, National 

Marine Fisheries Service and should be 

submitted via email to 

ITP.StevenTucker@noaa.gov. 

Instructions: NMFS is not responsible 

for comments sent by any other method, 

to any other address or individual, or 

received after the end of the comment 

period. Comments, including all 

attachments, must not exceed a 25- 

megabyte file size. All comments 

received are a part of the public record 

and will generally be posted online at 

https://www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

incidental-take-authorizations-oil-andgas without change. All personal 

identifying information (e.g., name, 

address) voluntarily submitted by the 

commenter may be publicly accessible. 

Do not submit confidential business 

information or otherwise sensitive or 

protected information. 

Electronic copies of the application 

and supporting documents, as well as a 

list of the references cited in this 

document, may be obtained online at: 

https://www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

incidental-take-authorizations-oil-andgas. In case of problems accessing these 

documents, please call the contact listed 

below. 

FOR FURTHER INFORMATION CONTACT: 

Steven Tucker, Office of Protected 

Resources, NMFS, (301) 427–8401. 

SUPPLEMENTARY INFORMATION: 

Background 

The MMPA prohibits the ‘‘take’’ of 

marine mammals, with certain 

exceptions. Sections 101(a)(5)(A) and 

(D) of the MMPA (16 U.S.C. 1361 et

seq.) direct the Secretary of Commerce

(as delegated to NMFS) 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 certain findings

are made and either regulations are

proposed or, if the taking is limited to

harassment, a notice of a proposed IHA

is provided to the public for review.

Authorization for incidental takings 

shall be granted if NMFS finds that the 

taking will have a negligible impact on 

the species or stock(s) and will not have 

an unmitigable adverse impact on the 

availability of the species or stock(s) for 

taking for subsistence uses (where 

relevant). Further, NMFS must prescribe 

the permissible methods of taking and 

other ‘‘means of effecting the least 


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practicable adverse impact’’ on the 

affected species or stocks and their 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance, and on the 

availability of the species or stocks for 

taking for certain subsistence uses 

(referred to in shorthand as 

‘‘mitigation’’); and requirements 

pertaining to the mitigation, monitoring 

and reporting of the takings are set forth. 

The definitions of all applicable MMPA 

statutory terms cited above are included 

in the relevant sections below. 

National Environmental Policy Act 

To comply with the National 

Environmental Policy Act of 1969 

(NEPA; 42 U.S.C. 4321 et seq.) and 

NOAA Administrative Order (NAO) 

216–6A, NMFS must review our 

proposed action (i.e., the issuance of an 

IHA) with respect to potential impacts 

on the human environment. 

This action is consistent with 

categories of activities identified in 

Categorical Exclusion B4 (IHAs with no 

anticipated serious injury or mortality) 

of the Companion Manual for NOAA 

Administrative Order 216–6A, which do 

not individually or cumulatively have 

the potential for significant impacts on 

the quality of the human environment 

and for which we have not identified 

any extraordinary circumstances that 

would preclude this categorical 

exclusion. Accordingly, NMFS has 

preliminarily determined that the 

issuance of the proposed IHA qualifies 

to be categorically excluded from 

further NEPA review. We will review all 

comments submitted in response to this 

notice prior to concluding our NEPA 

process or making a final decision on 

the IHA request. 

Summary of Request 

On March 3, 2023, NMFS received a 

request from TC Energy/Columbia Gulf 

Transmission, LLC (Columbia Gulf) for 

an IHA to take marine mammals 

incidental to construction activities that 

include pile driving to install: (1) a 

point of delivery metering station (or, 

POD), and (2) a tie-in facility (or, TIF) 

in Barataria Bay. The project is intended 

to provide feed fuel for on-shore 

Liquefied Natural Gas (LNG) compressor 

stations. The application was deemed 

adequate and complete on June 5, 2023. 

Columbia Gulf’s request is for take of 

bottlenose dolphin (Tursiops truncatus, 

Barataria Bay Estuarine System stock or, 

BBES) by Level B harassment only. 

Neither Columbia Gulf nor NMFS 

expects serious injury or mortality to 

result from this activity and, therefore, 

an IHA is appropriate. 

Description of Proposed Activity 

Overview 

Columbia Gulf Transmission, LLC, a 

wholly-owned subsidiary of TC Energy 

Corporation, proposes to construct two 

new compressor stations, a new meter 

station, approximately 8 miles (13 

kilometers) of new 30-inch diameter 

natural gas pipeline lateral, two new 

mainline valves, a tie-in facility, 

launcher and receiver facilities, and 

other auxiliary appurtenant facilities all 

located in St. Mary, Lafourche, 

Jefferson, and Plaquemines parishes, 

Louisiana (collectively referred to as 

‘‘Project’’). A summary of all 

construction activities necessary to 

complete the all elements of the project 

are shown in Table 1. 

TABLE 1—ALL ELEMENTS OF THE PROJECT. BOLDED ELEMENTS INCLUDE IN-WATER ACTIVITIES THAT MAY RESULT IN THE

TAKE OF MARINE MAMMALS

Facility Parish Pipeline milepost 

location Description 

Pipeline Facilities 

30-inch Pipeline Lateral Jefferson ..................... 0.00–2.47 Install approximately 13.1 kilometers (8.14) miles of new 30-inch-diameter pipeline lateral. 

Plaquemines ............... 2.47–8.14 

Aboveground Facilities 

Centerville Compressor 

Station.

St. Mary ...................... a 66.50, b 66.70, 

c 67.00 

Construct a new gas-fired compressor station with a 23,470 hp compressor unit, which will interconnect with Columbia Gulf’s existing 

EL–100, EL–200, and EL–300 pipelines. 

Golden Meadow Compressor Station.Lafourche ................... c 149.50 Construct a new gas-fired compressor station with a 23,470 hp compressor unit, which will interconnect with Columbia Gulf’s existing 

EL–300 pipeline. 

Point of Delivery 

Meter Station.

Plaquemines ............. 8.14 Construct one point of delivery meter station at the terminus of 

the new 30-inch pipeline lateral on an existing platform 

shared with Venture Global Gator Express, LLC. A 30-inch 

pig receiver will also be installed at the POD Meter Station. 

Tie-in Facility .............. Jefferson ................... 0.00 Install a new tie-in facility situated on a new platform at the 

intersection of the new 30-inch pipeline and Columbia Gulf’s 

existing EL–300 pipeline. A 30-inch pig launcher will also be 

Installed at the Tie-in Facility. 

Valves and Other Ancillary Facilities.Jefferson ..................... 0.00, c 1.71 Install one new 30-inch mainline valve assembly on the new 30-inch 

pipeline lateral and one new 24- inch mainline valve assembly 

Columbia Gulf’s existing EL–300 pipeline. Both mainline valve assemblies will be situated on the new Tie-in Facility platform. 

a Milepost is associated with Columbia Gulf’s existing EL–100 pipeline. 

b Milepost is associated with Columbia Gulf’s existing EL–200 pipeline. 

c Milepost is associated with Columbia Gulf’s existing EL–300 pipeline. 

The work necessary to complete 

construction of the project would 

temporarily impact 2.79 acres, 

permanently alter .02 acres and include 

in-water activity that may result in take 

of marine mammals in Barataria Bay. 

Specifically, in order to provide fuel 

supply services to onshore LNG 

compressor stations, Columbia Gulf 

proposes pile driving to construct a new 

Point of Delivery Meter Station on an 

existing platform and a new Tie-in 


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Facility at the terminus a new 30-inch 

lateral pipeline. Project activities 

include installation, by impact hammer, 

of 20 18-inch concrete piles and 104 36- 

inch spun cast piles. The new POD 

Meter Station will include the 

installation of three 16-inch meter runs 

and related facilities. The new POD 

Meter Station will be constructed at the 

site of an existing platform, and 

construction will require the installation 

of four new 18-inch square concrete 

piles to protect a 30-inch- diameter 

riser. Pipelines will be installed by 

jetting and dredging with displaced 

sediment precipitating back to the 

substrate or being side-cast adjacent to 

the trench, respectively. 

The new Tie-in Facility will be 

situated on a new 180 foot (55 meter) 

long by 80 foot (24.3 meter) wide 

platform supported by 104 36-inchdiameter spun cast and 4 18-inchdiameter concrete piles. Two 24-inchdiameter and one 30-inch-diameter 

risers will be protected by 12 a8-inch 

diameter concrete piles. The Tie-in 

Facility would include a boat landing 

measuring 10 foot (3 meter) long by 10 

foot (3 meter) wide, that will be used for 

maintenance and servicing of the 

platform. 

These activities would be supported 

by eight vessels using existing public 

barge channels and waterways during 

an estimated 16 barge trips per week. 

Because vessels will be in transit, 

exposure to ship noise will be 

temporary, relatively brief and will 

occur in a predictable manner, 

producing sound at a relatively low 

level and consistent with use of the 

waterway and other activity in the area. 

In order to reduce the number barge 

transits during construction, Columbia 

Gulf intends to station one or more 

barges onsite for hoteling of personnel. 

Dates and Duration 

Columbia Gulf proposes to start 

construction in January, 2024 in order to 

meet a planned in-service date of April, 

2025. Pile driving within Barataria Bay 

is anticipated to occur within a 3 month 

period from January, 2025 to March, 

2025. Pile driving activity will be 

intermittent, conducted in accordance 

with project phasing requirements, and 

as such will not be continuous 

throughout the 3-month period. Pile 

driving activities would take place from 

7 a.m. to 7 p.m. (adjusted as appropriate 

to conduct work during daylight hours), 

and could occur on any day of the week 

for about 25 days (five piles per day). 

Specific Geographic Region 

Barataria Bay is a shallow estuarine 

system, and is categorized as an open 

bay habitat with a mean depth of 

approximately 2.0 meters (U.S. 

Environmental Protection Agency, 1999; 

Conner and Day, 1987). Archival data 

collected at NOAA’s St. Mary’s Point 

station indicate a mean tidal range of 

0.97 feet, with Mean High-High Water 

reference elevation of .47′ and Mean 

Low-Low Water reference elevation of 

¥2.32. The bay has two fronting barrier 

islands (Grand Isle and Grand Terre) 

that separate it from the rest of the Gulf 

of Mexico and that also inhibit 

underwater sound transmission from 

portions of the Bay to the coastal waters 

of the Gulf of Mexico. 

BILLING CODE 3510–22–P 


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BILLING CODE 3510–22–C 

Barataria Bay is bordered by tidal salt 

marshes and is connected to a series of 

passes (i.e., Caminada Pass, Barataria 

Pass, Pass Abel, and Quatre Bayou Pass) 

which, in turn, provide hydrologic 

connection to the waters of the Gulf of 

Mexico (NMFS, 2023a; Conner and Day, 

1987). To the east, Barataria Bay is 

bounded by levees surrounding the 

Mississippi River and to the west it is 

bordered by Bayou Lafourche (Birdsong, 

2004). The waters of Barataria Bay are 

turbid with lower salinity level 

(including the presence of freshwater 

lakes) in northern reaches. Higher 

salinity levels prevail in the southern 

portion of the bay due to tidally 

influenced exchange with Gulf coastal 

waters (NMFS, 2023a). As a result, 

measured salinity concentrations in 


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Barataria Bay can vary ranging from 6 to 

22 parts per trillion, depending on the 

sampling location. 

Detailed Description of the Specified 

Activity 

Columbia Gulf proposes to construct 

a POD Meter Station on an existing 

platform along with the new receiver at 

the terminus of a new 30-inch pipeline 

lateral within Barataria Bay. The new 

POD Meter Station requires installation 

of three 16-inch meter runs and related 

facilities. The new POD Meter Station is 

proposed for construction on an existing 

platform, and requires the installation of 

four 18-inch square concrete piles in 

order to protect a 30-inch-diameter riser. 

In addition to shore side construction 

and installation of the POD meter 

station, Columbia Gulf proposes to 

construct a new Tie-in Facility at the 

intersection of the new 30-inch pipeline 

lateral and Columbia Gulf’s existing EL– 

300 pipeline. With the exception of a 

portion of two new 24-inch-diameter 

risers and one new 30-inch-diameter 

riser which will be underwater, the Tiein Facility will be constructed on a new 

180 foot (55 meter) long by 80 foot (24.3 

meter) wide platform supported by 104 

36-inch-diameter spun cast and 4 18- 

inch-diameter concrete piles. Twelve 

18-inch-diameter concrete piles will be 

installed to protect the 2 24-inchdiameter and 1 30-inch-diameter risers. 

The new platform will also be equipped 

with a boat landing, which will measure 

10 feet (3 meters) long by 10 feet (3 

meters) wide and will enable 

maintenance activities during operation 

of the Project. 

Of the activities described in the 

application, noise from pile-driving is 

the only activity expected to result in 

level B harassment of bottlenose 

dolphins, and the implications of pile 

driving are discussed in greater detail 

below. The Piles and method of 

installation are presented in Table 2, 

below. 

TABLE 2—PROPOSED PILE DRIVING ACTIVITIES

Location Number of 

piles 

Proposed pile 

diameter/type 

Proxy pile for 

calculations 

Impact strikes 

per pile Piles per day Strikes per day 

Days of 

installation 

Tie-in Facility ...... 104 36′′ Spun Cast 

Concrete Piles.

36′′ Concrete 

(round, hollow).

4,800 5 24,000 24 

Tie-in Facility ...... 16 18′′ Concrete 

(round).

Point of Delivery 

Platform.

4 18′′ Concrete 

(square).

1 

Total ............ 120 25 

Proposed mitigation, monitoring, and 

reporting measures are described in 

detail later in this document (please see 

Proposed Mitigation and Proposed 

Monitoring and Reporting). 

Description of Marine Mammals in the 

Area of Specified Activities 

Sections 3 and 4 of the application 

summarize available information 

regarding status and trends, distribution 

and habitat preferences, and behavior 

and life history of the Barataria Bay 

Estuarine Stock (BBES) of bottlenose 

dolphins. NMFS fully considered all of 

this information, including relevant 

citations which may be included here, 

and we refer the reader to these 

materials instead of reprinting the 

information. Additional information 

regarding population estimates and 

potential threats for the Barataria Bay 

Estuarine System stock of bottlenose 

dolphins, can be found in NMFS’ Stock 

Assessment Reports (SARs; https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/marinemammal-stock-assessments) and more 

information about this species in 

general (e.g., physical and behavioral 

descriptions) may be found on NMFS’ 

website (https://

www.fisheries.noaa.gov/find-species). 

Take of BBES bottlenose dolphins 

may occur incidental to the specified 

activities described in the request for 

authorization. Information related to the 

population or stock, including 

regulatory status under the MMPA and 

Endangered Species Act (ESA) and 

potential biological removal (PBR), 

where known is provided in Table 3. 

PBR is defined by the MMPA as the 

maximum number of animals, not 

including natural mortalities, that may 

be removed from a marine mammal 

stock while allowing that stock to reach 

or maintain its optimum sustainable 

population (as described in NMFS’ 

SARs). While no serious injury or 

mortality is anticipated or proposed to 

be authorized here, PBR and annual 

serious injury and mortality from 

anthropogenic sources are included here 

as gross indicators of the status of the 

species or stocks and other threats. 

The BBES abundance estimate 

presented in this document represents 

the estimated total number of 

individuals within study and survey 

areas in Barataria Bay. BBES are one of 

several estuarine stocks fringing the 

northern Gulf of Mexico, and Barataria 

Bay is considered a Biologically 

Important Area year-round for the Small 

and Resident Population. In addition to 

Barataria Bay itself, individual BBES 

dolphins may be found in Caminada 

Bay, Bay Coquette, and Gulf coastal 

waters extending 1 kilometer (km) from 

the shoreline (NMFS, 2023a). 

The BBES stock was first designated 

in 1995 and is regarded as distinct from 

populations in adjacent Gulf coastal 

waters based on genetics, reproductive 

seasonality and direct observations. 

BBES bottlenose dolphins are present 

throughout Bay year-round including in 

the vicinity of the proposed 

construction site. Accordingly, when 

estimating take and weighing potential 

impacts, BBES dolphin abundance, 

density and distribution is presumed to 

be consistent throughout the 

construction period. No additional 

assumptions or qualitative adjustments 

were made based on seasonality. The 

values presented in Table 2 are the most 

recent available at the time of 

publication (including the draft 2022 

SARs) and are available online at: 

https://www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

marine-mammal-stock-assessments. 


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TABLE 3—MARINE MAMMALS LIKELY IMPACTED BY THE SPECIFIED ACTIVITIES

Common name Scientific name Stock ESA/MMPA status; 

strategic (Y/N) 2

Stock 

abundance 

(CV, Nmin, 

most recent 

abundance 

survey) 3

PBR Annual 

M/SI 4

Family Delphinidae 

Bottlenose Dolphin .................... Tursiops truncatus .................... Barataria Bay Estuarine Stock Y—Strategic ......... 2,071 18 160 

1 Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy’s Committee on Taxonomy 

(https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022). 2Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the 

ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or 

which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically 

designated under the MMPA as depleted and as a strategic stock. 3 NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of stock 

abundance. 4These values, found in NMFS’s SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, vessel strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases. 

As described above, animals from the 

BBES stock of bottlenose dolphins 

temporarily and spatially co-occur with 

the activity to the degree that take is 

reasonably likely to occur. While other 

marine mammal species may occur in 

offshore waters of the Gulf of Mexico, 

the characteristics of Barataria Bay make 

transits or sustained presence in the 

area affected by the specified activity 

exceedingly unlikely and as a result take 

is not expected to occur. Given take of 

other marine mammal species is not 

expected, they are not discussed further. 

The BBES stock has been affected by 

three declared unusual mortality events, 

all of which are now closed. The first 

spanned January through May of 1990 

(in which 344 individuals became 

stranded), the second from March 2010 

to July 2014 (which included stranding 

before, during, and after the Deepwater 

Horizon (DWH) oil spill), and the third 

from February to November of 2019 and 

was found to be a result of freshwater 

discharge from rivers (NMFS, 2023a). 

Research conducted after the DWH oil 

spill found that the BBES dolphins 

suffered a wide range of effects, 

including impaired reproduction, 

respiratory illness, other diseases, and 

death. These and other physiological 

and environmental challenges that 

followed the spill impacted individual 

animals’ ability to thrive and 

diminished the health of the stock. In 

Barataria Bay alone, it is estimated that 

45 percent of the common bottlenose 

dolphin population was lost following 

the spill (Schwacke et al., 2021). 

NMFS regards BBES dolphins to be a 

strategic stock. Insufficient data exists to 

assess population trends for the stock. 

However, impacts examined in the 

course of past Unusual Mortality Events, 

including impacts from the DWH oil 

spill and changes in habitat 

characteristics, coupled with an 

estimated PBR rate greater than 10 

percent support the Service’s finding 

that the stock is strategic. 

LeBreque et al. (2015) identified a 

small and resident population 

Biologically Important Area for 

bottlenose dolphins in the Caminada 

Bay and Southwest Barataria Bay area, 

indicating that the range of this small 

population is limited to this area. 

Marine Mammal Hearing 

Hearing is the most important sensory 

modality for marine mammals 

underwater, and exposure to 

anthropogenic sound can have 

deleterious effects. To appropriately 

assess the potential effects of exposure 

to sound, it is necessary to understand 

the frequency ranges marine mammals 

are able to hear. Not all marine mammal 

species have equal hearing capabilities 

(e.g., Richardson et al., 1995; Wartzok 

and Ketten, 1999; Au and Hastings, 

2008). To reflect this, Southall et al. 

(2007, 2019) recommended that marine 

mammals be divided into hearing 

groups based on directly measured 

(behavioral or auditory evoked potential 

techniques) or estimated hearing ranges 

(behavioral response data, anatomical 

modeling, etc.). Note that no direct 

measurements of hearing ability have 

been successfully completed for 

mysticetes (i.e., low-frequency 

cetaceans). Subsequently, NMFS (2018) 

described generalized hearing ranges for 

these marine mammal hearing groups. 

Generalized hearing ranges were chosen 

based on the approximately 65 decibel 

(dB) threshold from the normalized 

composite audiograms, with the 

exception for lower limits for lowfrequency cetaceans where the lower 

bound was deemed to be biologically 

implausible and the lower bound from 

Southall et al. (2007) retained. Marine 

mammal hearing groups and their 

associated hearing ranges are provided 

in Table 4. 

TABLE 4—MARINE MAMMAL HEARING GROUPS (NMFS, 2018) 

Hearing group Generalized hearing 

range * 

Low-frequency (LF) cetaceans (baleen whales) ........................................................................................................................ 7 Hz to 35 kHz. 

Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) .............................................. 150 Hz to 160 kHz. 

High-frequency (HF) cetaceans ..................................................................................................................................................

(true porpoises, Kogia, river dolphins, Cephalorhynchid, Lagenorhynchus cruciger & L. australis) .........................................

275 Hz to 160 kHz. 

Phocid pinnipeds (PW) (underwater) (true seals) ...................................................................................................................... 50 Hz to 86 kHz. 

Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) ................................................................................................. 60 Hz to 39 kHz. 

* Represents the generalized hearing range for the entire group as a composite (i.e., all species within the group), where individual species’ 

hearing ranges are typically not as broad. Generalized hearing range chosen based on ∼65 dB threshold from normalized composite audiogram, 

with the exception for lower limits for LF cetaceans (Southall et al. 2007) and PW pinniped (approximation). 


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The pinniped hearing group was 

modified from Southall et al. (2007) on 

the basis of data indicating that phocid 

species have consistently demonstrated 

an extended frequency range of hearing 

compared to otariids, especially in the 

higher frequency range (Hemila ̈ et al., 

2006; Kastelein et al., 2009; Reichmuth 

et al., 2013). This division between 

phocid and otariid pinnipeds is now 

reflected in the updated hearing groups 

proposed in Southall et al. (2019). 

For more detail concerning these 

groups and associated frequency ranges, 

please see NMFS (2018) for a review of 

available information. 

Potential Effects of Specified Activities 

on Marine Mammals and Their Habitat 

This section provides a discussion of 

the ways in which components of the 

specified activity may impact marine 

mammals and their habitat. The 

Estimated Take of Marine Mammals 

section later in this document presents 

the number of individual animals that 

are expected to be taken by this activity. 

The Negligible Impact Analysis and 

Determination section considers the 

content of this section, the Estimated 

Take of Marine Mammals section, and 

the Proposed Mitigation section, to draw 

conclusions regarding the likely impacts 

of these activities on the reproductive 

success or survivorship of individuals 

and whether those impacts are 

reasonably expected to, or reasonably 

likely to, adversely affect the species or 

stock through effects on annual rates of 

recruitment or survival. 

Acoustic effects on marine mammals 

during the specified activity are 

expected to potentially occur from 

impact pile driving. The effects of 

underwater noise from Columbia Gulf’s 

activities have the potential to result in 

Level B harassment of marine mammals 

in the action area. These activities are 

not expected to cause serious injury or 

mortality, and no take by Level A 

harassment is proposed. 

Background on Sound 

This section contains a brief technical 

background on sound, on the 

characteristics of certain sound types, 

and on metrics used relevant to the 

specified activity and to a discussion of 

the potential effects of the specified 

activity on marine mammals found later 

in this document. For general 

information on sound and its interaction 

with the marine environment, please 

see, Erbe and Thomas (2022); Au and 

Hastings (2008); Richardson et al. 

(1995); Urick (1983); as well as the 

Discovery of Sound in the Sea (DOSITS) 

website at https://dosits.org/. 

Sound is a vibration that travels as an 

acoustic wave through a medium such 

as a gas, liquid or solid. Sound waves 

alternately compress and decompress 

the medium as the wave travels. In 

water, sound waves radiate in a manner 

similar to ripples on the surface of a 

pond and may be either directed in a 

beam (narrow beam or directional 

sources) or sound may radiate in all 

directions (omnidirectional sources), as 

is the case for sound produced by the 

pile driving activity considered here. 

The compressions and decompressions 

associated with sound waves are 

detected as changes in pressure by 

marine mammals and human-made 

sound receptors such as hydrophones. 

Sound travels more efficiently in 

water than almost any other form of 

energy, making the use of sound as a 

primary sensory modality ideal for 

inhabitants of the aquatic environment. 

In seawater, sound travels at roughly 

1,500 meters per second (m/s). In air, 

sound waves travel much more slowly 

at about 340 m/s. However, the speed of 

sound in water can vary by a small 

amount based on characteristics of the 

transmission medium such as 

temperature and salinity. 

The basic characteristics of a sound 

wave are frequency, wavelength, 

velocity, and amplitude. Frequency is 

the number of pressure waves that pass 

by a reference point per unit of time and 

is measured in hertz (Hz) or cycles per 

second. Wavelength is the distance 

between two peaks or corresponding 

points of a sound wave (length of one 

cycle). Higher frequency sounds have 

shorter wavelengths than lower 

frequency sounds, and typically 

attenuate (decrease) more rapidly with 

distance, except in certain cases in 

shallower water. The amplitude of a 

sound pressure wave is related to the 

subjective ‘‘loudness’’ of a sound and is 

typically expressed in decibels (dB), 

which are a relative unit of 

measurement that is used to express the 

ratio of one value of a power or pressure 

to another. A sound pressure level (SPL) 

in dB is described as the ratio between 

a measured pressure and a reference 

pressure, and is a logarithmic unit that 

accounts for large variations in 

amplitude; therefore, a relatively small 

change in dB corresponds to large 

changes in sound pressure. For 

example, a 10-dB increase is a ten-fold 

increase in acoustic power. A 20-dB 

increase is then a 100-fold increase in 

power and a 30-dB increase is a 1000- 

fold increase in power. However, a tenfold increase in acoustic power does not 

mean that the sound is perceived as 

being 10 times louder. The dB is a 

relative unit comparing two pressures; 

therefore, a reference pressure must 

always be indicated. For underwater 

sound, this is 1 microPascal (mPa). For 

in-air sound, the reference pressure is 

20 microPascal (mPa). The amplitude of 

a sound can be presented in various 

ways; however, NMFS typically 

considers three metrics: sound exposure 

level (SEL), root-mean-square (RMS) 

SPL, and peak SPL (defined below). The 

source level represents the SPL 

referenced at a standard distance from 

the source (Richardson et al., 1995; 

American National Standards Institute 

(ANSI), 2013)(typically 1 m) 

(Richardson et al., 1995; American 

National Standards Institute (ANSI), 

2013), while the received level is the 

SPL at the receiver’s position. For pile 

driving activities, the SPL is typically 

referenced at 10 m. 

SEL (represented as dB referenced to 

1 micropascal squared second (re 1 

mPa2-s)) represents the total energy in a 

stated frequency band over a stated time 

interval or event, and considers both 

intensity and duration of exposure. The 

per-pulse SEL (e.g., single strike or 

single shot SEL) is calculated over the 

time window containing the entire 

pulse (i.e., 100 percent of the acoustic 

energy). SEL can also be a cumulative 

metric; it can be accumulated over a 

single pulse (for pile driving this is the 

same as single-strike SEL, above; SELss), 

or calculated over periods containing 

multiple pulses (SELcum). Cumulative 

SEL (SELcum) represents the total energy 

accumulated by a receiver over a 

defined time window or during an 

event. The SEL metric is useful because 

it allows sound exposures of different 

durations to be related to one another in 

terms of total acoustic energy. The 

duration of a sound event and the 

number of pulses, however, should be 

specified as there is no accepted 

standard duration over which the 

summation of energy is measured. 

RMS SPL is equal to ten times the 

logarithm (base 10) of the ratio of the 

mean-square sound pressure to the 

specified reference value, and given in 

units of dB (International Organization 

for Standardization (ISO), 2017). RMS is 

calculated by squaring all of the sound 

amplitudes, averaging the squares, and 

then taking the square root of the 

average (Urick, 1983). RMS accounts for 

both positive and negative values; 

squaring the pressures makes all values 

positive so that they may be accounted 

for in the summation of pressure levels 

(Hastings and Popper, 2005). This 

measurement is often used in the 

context of discussing behavioral effects, 

in part because behavioral effects, 

which often result from auditory cues, 

may be better expressed through 


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averaged units than by peak SPL. For 

impulsive sounds, RMS is calculated by 

the portion of the waveform containing 

90 percent of the sound energy from the 

impulsive event (Madsen, 2005). 

Peak SPL (also referred to as zero-topeak sound pressure or 0-pk) is the 

maximum instantaneous sound pressure 

measurable in the water, which can 

arise from a positive or negative sound 

pressure, during a specified time, for a 

specific frequency range at a specified 

distance from the source, and is 

represented in the same units as the 

RMS sound pressure (ISO, 2017). Along 

with SEL, this metric is used in 

evaluating the potential for permanent 

threshold shift (PTS) and temporary 

threshold shift (TTS) associated with 

impulsive sound sources. 

Sounds are also characterized by their 

temporal components. Continuous 

sounds are those whose sound pressure 

level remains above that of the ambient 

or background sound with negligibly 

small fluctuations in level (ANSI, 2005) 

while intermittent sounds are defined as 

sounds with interrupted levels of low or 

no sound (National Institute for 

Occupational Safety and Health 

(NIOSH), 1998). A key distinction 

between continuous and intermittent 

sound sources is that intermittent 

sounds have a more regular 

(predictable) pattern of bursts of sounds 

and silent periods (i.e., duty cycle), 

which continuous sounds do not. 

Sounds may be either impulsive or 

non-impulsive (defined below). The 

distinction between these two sound 

types is important because they have 

differing potential to cause physical 

effects, particularly with regard to noiseinduced hearing loss (e.g., Ward, 1997 

in Southall et al., 2007). Please see 

NMFS (2018) and Southall et al. (2007; 

2019) for an in-depth discussion of 

these concepts. 

Impulsive sound sources (e.g., sonic 

booms, seismic airgun shots, impact pile 

driving) produce signals that are brief 

(typically considered to be less than one 

second), broadband, atonal transients 

(ANSI, 1986; NIOSH, 1998; ANSI, 2005) 

and occur either as isolated events or 

repeated in some succession. Impulsive 

sounds are all characterized by a 

relatively rapid rise from ambient 

pressure to a maximal pressure value 

followed by a rapid decay period that 

may include a period of diminishing, 

oscillating maximal and minimal 

pressures, and generally have an 

increased capacity to induce physical 

injury as compared with sounds that 

lack these features. Impulsive sounds 

are intermittent in nature. The duration 

of such sounds, as received at a 

distance, can be greatly extended in a 

highly reverberant environment. 

Non-impulsive sounds can be tonal, 

narrowband, or broadband, brief or 

prolonged, and may be either 

continuous or non-continuous (ANSI, 

1995; NIOSH, 1998). Some of these nonimpulsive sounds can be transient 

signals of short duration but without the 

essential properties of impulses (e.g., 

rapid rise time). Examples of nonimpulsive sounds include those 

produced by vessels, aircraft, machinery 

operations such as drilling (including 

DTH systems) or dredging, vibratory 

pile driving, and active sonar systems. 

Even in the absence of sound from the 

specified activity, the underwater 

environment is characterized by sounds 

from both natural and anthropogenic 

sound sources. Ambient sound is 

defined as a composite of naturallyoccurring (i.e. non-anthropogenic) 

sound from many sources both near and 

far (ANSI, 1995). Background sound is 

similar, but includes all sounds, 

including anthropogenic sounds, minus 

the sound produced by the proposed 

(NMFS, 2012; 2016). The sound level of 

a region is defined by the total 

acoustical energy being generated by 

known and unknown sources. These 

sources may include physical (e.g., 

wind and waves, earthquakes, ice, 

atmospheric sound), biological (e.g., 

sounds produced by marine mammals, 

fish, and invertebrates), and 

anthropogenic (e.g., vessels, dredging, 

construction) sound. A number of 

sources contribute to background and 

ambient sound, including wind and 

waves, which are a main source of 

naturally occurring ambient sound for 

frequencies between 200 Hz and 50 

kilohertz (kHz) (Mitson, 1995). In 

general, background and ambient sound 

levels tend to increase with increasing 

wind speed and wave height. 

Precipitation can become an important 

component of total sound at frequencies 

above 500 Hz, and possibly down to 100 

Hz during quiet times. Marine mammals 

can contribute significantly to 

background and ambient sound levels, 

as can some fish and snapping shrimp. 

The frequency band for biological 

contributions is from approximately 12 

Hz to over 100 kHz. Sources of 

background sound related to human 

activity include transportation (surface 

vessels), dredging and construction, oil 

and gas drilling and production, 

geophysical surveys, sonar, and 

explosions. Vessel noise typically 

dominates the total background sound 

for frequencies between 20 and 300 Hz. 

In general, the frequencies of many 

anthropogenic sounds, particularly 

those produced by construction 

activities, are below 1 kHz (Richardson 

et al., 1995). When sounds at 

frequencies greater than 1 kHz are 

produced, they generally attenuate 

relatively rapidly (Richardson et al., 

1995), particularly above 20 kHz due to 

propagation losses and absorption 

(Urick, 1983). 

Transmission loss (TL) defines the 

degree to which underwater sound has 

spread in space and lost energy after 

having moved through the environment 

and reached a receiver. It is defined by 

the International Standards 

Organization (ISO) as the reduction in a 

specified level between two specified 

points that are within an underwater 

acoustic field (ISO, 2017). Careful 

consideration of transmission loss and 

appropriate propagation modeling is a 

crucial step in determining the impacts 

of underwater sound, as it helps to 

define the ranges (isopleths) to which 

impacts are expected and depends 

significantly on local environmental 

parameters such as seabed type, water 

depth (bathymetry), and the local speed 

of sound. Geometric spreading laws are 

powerful tools which provide a simple 

means of estimating TL, based on the 

shape of the sound wave front in the 

water column. For a sound source that 

is equally loud in all directions and in 

deep water, the sound field takes the 

form of a sphere, as the sound extends 

in every direction uniformly. In this 

case, the intensity of the sound is spread 

across the surface of the sphere, and 

thus we can relate intensity loss to the 

square of the range (as area = 4*pi*r2). 

When expressing logarithmically in dB 

as TL, we find that TL = 

20*Log10(range), this situation is known 

as spherical spreading. In shallow 

water, the sea surface and seafloor will 

bound the shape of the sound, leading 

to a more cylindrical shape, as the top 

and bottom of the sphere is truncated by 

the largely reflective boundaries. This 

situation is termed cylindrical 

spreading, and is given by TL = 

10*Log10(range) (Urick, 1983). An 

intermediate scenario may be defined by 

the equation TL = 15*Log10(range), and 

is referred to as practical spreading. 

Though these geometric spreading laws 

do not capture many often important 

details (scattering, absorption, etc.), they 

offer a reasonable and simple 

approximation of how sound decreases 

in intensity as it is transmitted. In the 

absence of measured data indicating the 

level of transmission loss at a given site 

for a specific activity, NMFS 

recommends practical spreading (i.e., 

15*Log10(range)) to model acoustic 

propagation for construction activities 

in most nearshore environments. 


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The sum of the various natural and 

anthropogenic sound sources at any 

given location and time depends not 

only on the source levels, but also on 

the propagation of sound through the 

environment. Sound propagation is 

dependent on the spatially and 

temporally varying properties of the 

water column and sea floor, and is 

frequency-dependent. As a result of the 

dependence on a large number of 

varying factors, background and 

ambient sound levels can be expected to 

vary widely over both coarse and fine 

spatial and temporal scales. Sound 

levels at a given frequency and location 

can vary by 10–20 dB from day to day 

(Richardson et al., 1995). The result is 

that, depending on the source type and 

its intensity, sound from the specified 

activity may be a negligible addition to 

the local environment or could form a 

distinctive signal that may affect marine 

mammals. 

Description of Sound Sources for the 

Specified Activities 

In-water construction activities 

expected to generate sound at levels 

resulting in Level B harassment include 

impact pile installation. Impact 

hammers operate by repeatedly 

dropping and/or pushing a heavy piston 

onto a pile to drive the pile into the 

substrate. Sound generated by impact 

hammers is impulsive, characterized by 

rapid rise times and high peak levels, a 

potentially injurious combination 

(Hastings and Popper, 2005). 

The likely or possible impacts of the 

Columbia Gulf’s proposed activities on 

marine mammals could involve both 

non-acoustic and acoustic stressors. 

Potential non-acoustic stressors could 

result from the physical presence of the 

equipment and personnel; however, 

visual and other non-acoustic stressors 

would be limited, and any impacts to 

marine mammals are expected to 

primarily be acoustic in nature. 

Acoustic Impacts 

The introduction of anthropogenic 

noise into the aquatic environment from 

pile driving or drilling is the primary 

means by which marine mammals may 

be harassed from the Columbia Gulf’s 

specified activity. In general, animals 

exposed to natural or anthropogenic 

sound may experience physical and 

psychological effects, ranging in 

magnitude from none to severe 

(Southall et al., 2007; 2019). Exposure to 

pile driving has the potential to result 

in auditory threshold shifts and 

behavioral reactions (e.g., avoidance, 

temporary cessation of foraging and 

vocalizing, changes in dive behavior). 

Exposure to anthropogenic noise can 

also lead to non-observable 

physiological responses, such an 

increase in stress hormones. Additional 

noise in a marine mammal’s habitat can 

mask acoustic cues used by marine 

mammals to carry out daily functions, 

such as communication and predator 

and prey detection. The effects of pile 

driving on marine mammals is 

dependent on several factors, including, 

but not limited to, sound type (e.g., 

impulsive vs. non-impulsive), the 

species, age and sex class (e.g., adult 

male vs. mom with calf), duration of 

exposure, the distance between the pile 

and the animal, received levels, 

behavior at time of exposure, and 

previous history with exposure 

(Wartzok et al., 2004; Southall et al., 

2007). Here we discuss physical 

auditory effects (threshold shifts) 

followed by behavioral effects and 

potential impacts on habitat. 

NMFS defines a noise-induced 

threshold shift (TS) as a change, usually 

an increase, in the threshold of 

audibility at a specified frequency or 

portion of an individual’s hearing range 

above a previously established reference 

level (NMFS, 2018). The amount of 

threshold shift is customarily expressed 

in dB. A TS can be permanent or 

temporary. As described in NMFS, 

2018, there are numerous factors to 

consider when examining the 

consequence of TS, including, but not 

limited to, the signal temporal pattern 

(e.g., impulsive or non-impulsive), 

likelihood an individual would be 

exposed for a long enough duration or 

to a high enough level to induce a TS, 

the magnitude of the TS, time to 

recovery (seconds to minutes or hours to 

days), the frequency range of the 

exposure (i.e., spectral content), the 

hearing frequency range of the exposed 

species relative to the signal’s frequency 

spectrum (i.e., how animal uses sound 

within the frequency band of the signal; 

e.g., Kastelein et al. (2014)), and the 

overlap between the animal and the 

source (e.g., spatial, temporal, and 

spectral). When considering auditory 

effects for Columbia Gulf’s proposed 

activities, impact pile driving is treated 

as an impulsive source. 

Permanent Threshold Shift (PTS)— 

NMFS defines PTS as a permanent, 

irreversible increase in the threshold of 

audibility at a specified frequency or 

portion of an individual’s hearing range 

above a previously established reference 

level (NMFS, 2018). PTS does not 

generally affect more than a limited 

frequency range, and an animal that has 

incurred PTS has incurred some level of 

hearing loss at the relevant frequencies; 

typically animals with PTS are not 

functionally deaf (Au and Hastings, 

2008; Finneran, 2016). Available data 

from humans and other terrestrial 

mammals indicate that a 40 dB 

threshold shift approximates PTS onset 

(see Ward et al. (1958; 1959); Ward, 

1960; Kryter et al., 1966; Miller, 1974; 

Ahroon et al., 1996; Henderson et al., 

2008). PTS levels for marine mammals 

are estimates, as with the exception of 

a single study unintentionally inducing 

PTS in a harbor seal (Kastak et al., 

2008), there are no empirical data 

measuring PTS in marine mammals 

largely due to the fact that, for various 

ethical reasons, experiments involving 

anthropogenic noise exposure at levels 

inducing PTS are not typically pursued 

or authorized (NMFS, 2018). 

Temporary Threshold Shift (TTS)—A 

temporary, reversible increase in the 

threshold of audibility at a specified 

frequency or portion of an individual’s 

hearing range above a previously 

established reference level (NMFS, 

2018). Based on data from marine 

mammal TTS measurements (see 

Southall et al. (2007; 2019)), a TTS of 6 

dB is considered the minimum 

threshold shift clearly larger than any 

day-to-day or session-to-session 

variation in a subject’s normal hearing 

ability (Finneran et al., 2000; Schlundt 

et al., 2000; Finneran et al., 2002). As 

described in Finneran (2015), marine 

mammal studies have shown the 

amount of TTS increases with SELcum 

in an accelerating fashion: at low 

exposures with lower SELcum, the 

amount of TTS is typically small and 

the growth curves have shallow slopes. 

At exposures with higher SELcum, the 

growth curves become steeper and 

approach linear relationships with the 

noise SEL. 

Depending on the degree (elevation of 

threshold in dB), duration (i.e., recovery 

time), and frequency range of TTS, and 

the context in which it is experienced, 

TTS can have effects on marine 

mammals ranging from discountable to 

serious (similar to those discussed in 

auditory masking, below). For example, 

a marine mammal may be able to readily 

compensate for a brief, relatively small 

amount of TTS in a non-critical 

frequency range that takes place during 

a time when the animal is traveling 

through the open ocean, where ambient 

noise is lower and there are not as many 

competing sounds present. 

Alternatively, a larger amount and 

longer duration of TTS sustained during 

time when communication is critical for 

successful mother/calf interactions 

could have more serious impacts. We 

note that reduced hearing sensitivity as 

a simple function of aging has been 

observed in marine mammals, as well as 

humans and other taxa (Southall et al., 


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2007), so we can infer that strategies 

exist for coping with this condition to 

some degree, though likely not without 

cost. 

Many studies have examined noiseinduced hearing loss in marine 

mammals (see Finneran (2015) and 

Southall et al. (2019) for summaries). 

TTS is the mildest form of hearing 

impairment that can occur during 

exposure to sound (Kryter, 2013). While 

experiencing TTS, the hearing threshold 

rises, and a sound must be at a higher 

level in order to be heard. In terrestrial 

and marine mammals, TTS can last from 

minutes or hours to days (in cases of 

strong TTS). In many cases, hearing 

sensitivity recovers rapidly after 

exposure to the sound ends. For 

cetaceans, published data on the onset 

of TTS are limited to captive bottlenose 

dolphin (Tursiops truncatus), beluga 

whale (Delphinapterus leucas), harbor 

porpoise (Phocoena phocoena), and 

Yangtze finless porpoise (Neophocoena 

asiaeorientalis) (Southall et al., 2019). 

These studies examine hearing 

thresholds measured in marine 

mammals before and after exposure to 

intense or long-duration sound 

exposures. The difference between the 

pre-exposure and post-exposure 

thresholds can be used to determine the 

amount of threshold shift at various 

post-exposure times. 

The amount and onset of TTS 

depends on the exposure frequency. 

Sounds at low frequencies, well below 

the region of best sensitivity for a 

species or hearing group, are less 

hazardous than those at higher 

frequencies, near the region of best 

sensitivity (Finneran and Schlundt, 

2013). At low frequencies, onset-TTS 

exposure levels are higher compared to 

those in the region of best sensitivity 

(i.e., a low frequency noise would need 

to be louder to cause TTS onset when 

TTS exposure level is higher), as shown 

for harbor porpoises and harbor seals 

(Kastelein et al., 2019a; 2019c). Note 

that in general, harbor seals and harbor 

porpoises have a lower TTS onset than 

other measured pinniped or cetacean 

species (Finneran, 2015). In addition, 

TTS can accumulate across multiple 

exposures, but the resulting TTS will be 

less than the TTS from a single, 

continuous exposure with the same SEL 

(Mooney et al., 2009; Finneran et al., 

2010; Kastelein et al., 2014; 2015). This 

means that TTS predictions based on 

the total, cumulative SEL will 

overestimate the amount of TTS from 

intermittent exposures, such as sonars 

and impulsive sources. Nachtigall et al. 

(2018) describe measurements of 

hearing sensitivity of multiple 

odontocete species (bottlenose dolphin, 

harbor porpoise, beluga, and false killer 

whale (Pseudorca crassidens)) when a 

relatively loud sound was preceded by 

a warning sound. These captive animals 

were shown to reduce hearing 

sensitivity when warned of an 

impending intense sound. Based on 

these experimental observations of 

captive animals, the authors suggest that 

wild animals may dampen their hearing 

during prolonged exposures or if 

conditioned to anticipate intense 

sounds. Another study showed that 

echolocating animals (including 

odontocetes) might have anatomical 

specializations that might allow for 

conditioned hearing reduction and 

filtering of low-frequency ambient 

noise, including increased stiffness and 

control of middle ear structures and 

placement of inner ear structures 

(Ketten et al., 2021). Data available on 

noise-induced hearing loss for 

mysticetes are currently lacking (NMFS, 

2018). Additionally, the existing marine 

mammal TTS data come from a limited 

number of individuals within these 

species. 

Relationships between TTS and PTS 

thresholds have not been studied in 

marine mammals, and there is no PTS 

data for cetaceans, but such 

relationships are assumed to be similar 

to those in humans and other terrestrial 

mammals. PTS typically occurs at 

exposure levels at least several decibels 

above that inducing mild TTS (e.g., a 

40-dB threshold shift approximates PTS 

onset (Kryter et al., 1966; Miller, 1974), 

while a 6-dB threshold shift 

approximates TTS onset (Southall et al., 

2007; 2019). Based on data from 

terrestrial mammals, a precautionary 

assumption is that the PTS thresholds 

for impulsive sounds (such as impact 

pile driving pulses as received close to 

the source) are at least 6 dB higher than 

the TTS threshold on a peak-pressure 

basis and PTS cumulative sound 

exposure level thresholds are 15 to 20 

dB higher than TTS cumulative sound 

exposure level thresholds (Southall et 

al., 2007; 2019). Given the higher level 

of sound or longer exposure duration 

necessary to cause PTS as compared 

with TTS, it is considerably less likely 

that PTS could occur. 

Behavioral Harassment—Exposure to 

noise also has the potential to 

behaviorally disturb marine mammals to 

a level that rises to the definition of 

harassment under the MMPA. Generally 

speaking, NMFS considers a behavioral 

disturbance that rises to the level of 

harassment under the MMPA a nonminor response—in other words, not 

every response qualifies as behavioral 

disturbance, and for responses that do, 

those of a higher level, or accrued across 

a longer duration, have the potential to 

affect foraging, reproduction, or 

survival. Behavioral disturbance may 

include a variety of effects, including 

subtle changes in behavior (e.g., minor 

or brief avoidance of an area or changes 

in vocalizations), more conspicuous 

changes in similar behavioral activities, 

and more sustained and/or potentially 

severe reactions, such as displacement 

from or abandonment of high-quality 

habitat. Behavioral responses may 

include changing durations of surfacing 

and dives, changing direction and/or 

speed; reducing/increasing vocal 

activities; changing/cessation of certain 

behavioral activities (such as socializing 

or feeding); eliciting a visible startle 

response or aggressive behavior (such as 

tail/fin slapping or jaw clapping); 

avoidance of areas where sound sources 

are located. Behavioral responses to 

sound are highly variable and contextspecific and any reactions depend on 

numerous intrinsic and extrinsic factors 

(e.g., species, state of maturity, 

experience, current activity, 

reproductive state, auditory sensitivity, 

time of day), as well as the interplay 

between factors (e.g., Richardson et al., 

1995; Wartzok et al., 2004; Southall et 

al., 2007; Weilgart, 2007; Archer et al., 

2010; Southall et al., 2019). Behavioral 

reactions can vary not only among 

individuals but also within an 

individual, depending on previous 

experience with a sound source, 

context, and numerous other factors 

(Ellison et al., 2012), and can vary 

depending on characteristics associated 

with the sound source (e.g., whether it 

is moving or stationary, number of 

sources, distance from the source). 

Please see Appendices B and C of 

Southall et al. (2007) and Gomez et al. 

(2016) for reviews of studies involving 

marine mammal behavioral responses to 

sound. 

Habituation can occur when an 

animal’s response to a stimulus wanes 

with repeated exposure, usually in the 

absence of unpleasant associated events 

(Wartzok et al., 2004). Animals are most 

likely to habituate to sounds that are 

predictable and unvarying. It is 

important to note that habituation is 

appropriately considered as a 

‘‘progressive reduction in response to 

stimuli that are perceived as neither 

aversive nor beneficial,’’ rather than as, 

more generally, moderation in response 

to human disturbance (Bejder et al., 

2009). The opposite process is 

sensitization, when an unpleasant 

experience leads to subsequent 

responses, often in the form of 

avoidance, at a lower level of exposure. 

As noted above, behavioral state may 

affect the type of response. For example, 


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animals that are resting may show 

greater behavioral change in response to 

disturbing sound levels than animals 

that are highly motivated to remain in 

an area for feeding (Richardson et al., 

1995; Wartzok et al., 2004; National 

Research Council (NRC), 2005). 

Controlled experiments with captive 

marine mammals have showed 

pronounced behavioral reactions, 

including avoidance of loud sound 

sources (Ridgway et al., 1997; Finneran 

et al., 2003). Observed responses of wild 

marine mammals to loud pulsed sound 

sources (typically seismic airguns or 

acoustic harassment devices) have been 

varied but often consist of avoidance 

behavior or other behavioral changes 

suggesting discomfort (Richardson et al., 

1995; Morton and Symonds, 2002; 

Nowacek et al., 2007). 

Available studies show wide variation 

in response to underwater sound; 

therefore, it is difficult to predict 

specifically how any given sound in a 

particular instance might affect marine 

mammals perceiving the signal. If a 

marine mammal does react briefly to an 

underwater sound by changing its 

behavior or moving a small distance, the 

impacts of the change are unlikely to be 

significant to the individual, let alone 

the stock or population. However, if a 

sound source displaces marine 

mammals from an important feeding or 

breeding area for a prolonged period, 

impacts on individuals and populations 

could be significant (e.g., Lusseau and 

Bejder, 2007; Weilgart, 2007; NRC, 

2005). However, there are broad 

categories of potential response, which 

we describe in greater detail here, that 

include alteration of dive behavior, 

alteration of foraging behavior, effects to 

breathing, interference with or alteration 

of vocalization, avoidance, and flight. 

Changes in dive behavior can vary 

widely and may consist of increased or 

decreased dive times and surface 

intervals as well as changes in the rates 

of ascent and descent during a dive (e.g., 

Frankel and Clark, 2000; Costa et al., 

2003; Ng and Leung, 2003; Nowacek et 

al., 2004; Goldbogen et al., 2013a, 

2013b). Variations in dive behavior may 

reflect interruptions in biologically 

significant activities (e.g., foraging) or 

they may be of little biological 

significance. The impact of an alteration 

to dive behavior resulting from an 

acoustic exposure depends on what the 

animal is doing at the time of the 

exposure and the type and magnitude of 

the response. 

Disruption of feeding behavior can be 

difficult to correlate with anthropogenic 

sound exposure, so it is usually inferred 

by observed displacement from known 

foraging areas, the appearance of 

secondary indicators (e.g., bubble nets 

or sediment plumes), or changes in dive 

behavior. As for other types of 

behavioral response, the frequency, 

duration, and temporal pattern of signal 

presentation, as well as differences in 

species sensitivity, are likely 

contributing factors to differences in 

response in any given circumstance 

(e.g., Croll et al., 2001; Nowacek et al., 

2004; Madsen et al., 2006; Yazvenko et 

al., 2007). A determination of whether 

foraging disruptions incur fitness 

consequences would require 

information on or estimates of the 

energetic requirements of the affected 

individuals and the relationship 

between prey availability, foraging effort 

and success, and the life history stage of 

the animal. 

Respiration rates vary naturally with 

different behaviors and alterations to 

breathing rate as a function of acoustic 

exposure can be expected to co-occur 

with other behavioral reactions, such as 

a flight response or an alteration in 

diving. However, respiration rates in 

and of themselves may be representative 

of annoyance or an acute stress 

response. Various studies have shown 

that respiration rates may either be 

unaffected or could increase, depending 

on the species and signal characteristics, 

again highlighting the importance in 

understanding species differences in the 

tolerance of underwater noise when 

determining the potential for impacts 

resulting from anthropogenic sound 

exposure (e.g., Kastelein et al., 2001; 

2005; 2006; Gailey et al., 2007). 

Marine mammals vocalize for 

different purposes and across multiple 

modes, such as whistling, echolocation 

click production, calling, and singing. 

Changes in vocalization behavior in 

response to anthropogenic noise can 

occur for any of these modes and may 

result from a need to compete with an 

increase in background noise or may 

reflect increased vigilance or a startle 

response. For example, in the presence 

of potentially masking signals, 

humpback whales and killer whales 

have been observed to increase the 

length of their songs (Miller et al., 2000; 

Fristrup et al., 2003) or vocalizations 

(Foote et al., 2004), respectively, while 

North Atlantic right whales (Eubalaena 

glacialis) have been observed to shift the 

frequency content of their calls upward 

while reducing the rate of calling in 

areas of increased anthropogenic noise 

(Parks et al., 2007). In some cases, 

animals may cease sound production 

during production of aversive signals 

(Bowles et al., 1994). 

Avoidance is the displacement of an 

individual from an area or migration 

path as a result of the presence of a 

sound or other stressors, and is one of 

the most obvious manifestations of 

disturbance in marine mammals 

(Richardson et al., 1995). For example, 

gray whales (Eschrictius robustus) are 

known to change direction—deflecting 

from customary migratory paths—in 

order to avoid noise from seismic 

surveys (Malme et al., 1984). Avoidance 

may be short-term, with animals 

returning to the area once the noise has 

ceased (e.g., Bowles et al., 1994; Goold, 

1996; Stone et al., 2000; Morton and 

Symonds, 2002; Gailey et al., 2007). 

Longer-term displacement is possible, 

however, which may lead to changes in 

abundance or distribution patterns of 

the affected species in the affected 

region if habituation to the presence of 

the sound does not occur (e.g., 

Blackwell et al., 2004; Bejder et al., 

2006; Teilmann et al., 2006). 

A flight response is a dramatic change 

in normal movement to a directed and 

rapid movement away from the 

perceived location of a sound source. 

The flight response differs from other 

avoidance responses in the intensity of 

the response (e.g., directed movement, 

rate of travel). Relatively little 

information on flight responses of 

marine mammals to anthropogenic 

signals exist, although observations of 

flight responses to the presence of 

predators have occurred (Connor and 

Heithaus, 1996; Bowers et al., 2018). 

The result of a flight response could 

range from brief, temporary exertion and 

displacement from the area where the 

signal provokes flight to, in extreme 

cases, marine mammal strandings 

(England et al., 2001). However, it 

should be noted that response to a 

perceived predator does not necessarily 

invoke flight (Ford and Reeves, 2008), 

and whether individuals are solitary or 

in groups may influence the response. 

Behavioral disturbance can also 

impact marine mammals in more subtle 

ways. Increased vigilance may result in 

costs related to diversion of focus and 

attention (i.e., when a response consists 

of increased vigilance, it may come at 

the cost of decreased attention to other 

critical behaviors such as foraging or 

resting). These effects have generally not 

been demonstrated for marine 

mammals, but studies involving fishes 

and terrestrial animals have shown that 

increased vigilance may substantially 

reduce feeding rates (e.g., Beauchamp 

and Livoreil, 1997; Fritz et al., 2002; 

Purser and Radford, 2011). In addition, 

chronic disturbance can cause 

population declines through reduction 

of fitness (e.g., decline in body 

condition) and subsequent reduction in 

reproductive success, survival, or both 

(e.g., Harrington and Veitch, 1992; Daan 


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et al., 1996; Bradshaw et al., 1998). 

However, Ridgway et al. (2006) reported 

that increased vigilance in bottlenose 

dolphins exposed to sound over a 5-day 

period did not cause any sleep 

deprivation or stress effects. 

Many animals perform vital functions, 

such as feeding, resting, traveling, and 

socializing, on a diel cycle (24-hour 

cycle). Disruption of such functions 

resulting from reactions to stressors 

such as sound exposure are more likely 

to be significant if they last more than 

one diel cycle or recur on subsequent 

days (Southall et al., 2007). 

Consequently, a behavioral response 

lasting less than one day and not 

recurring on subsequent days is not 

considered particularly severe unless it 

could directly affect reproduction or 

survival (Southall et al., 2007). Note that 

there is a difference between multi-day 

substantive behavioral reactions and 

multi-day anthropogenic activities. For 

example, just because an activity lasts 

for multiple days does not necessarily 

mean that individual animals are either 

exposed to activity-related stressors for 

multiple days or, further, exposed in a 

manner resulting in sustained multi-day 

substantive behavioral responses. 

Stress responses—An animal’s 

perception of a threat may be sufficient 

to trigger stress responses consisting of 

some combination of behavioral 

responses, autonomic nervous system 

responses, neuroendocrine responses, or 

immune responses (e.g., Selye, 1950; 

Moberg, 2000). In many cases, an 

animal’s first and sometimes most 

economical (in terms of energetic costs) 

response is behavioral avoidance of the 

potential stressor. Autonomic nervous 

system responses to stress typically 

involve changes in heart rate, blood 

pressure, and gastrointestinal activity. 

These responses have a relatively short 

duration and may or may not have a 

significant long-term effect on an 

animal’s fitness. 

Neuroendocrine stress responses often 

involve the hypothalamus-pituitaryadrenal system. Virtually all 

neuroendocrine functions that are 

affected by stress—including immune 

competence, reproduction, metabolism, 

and behavior—are regulated by pituitary 

hormones. Stress-induced changes in 

the secretion of pituitary hormones have 

been implicated in failed reproduction, 

altered metabolism, reduced immune 

competence, and behavioral disturbance 

(e.g., Moberg, 1987; Blecha, 2000). 

Increases in the circulation of 

glucocorticoids are also equated with 

stress (Romano et al., 2004). 

The primary distinction between 

stress (which is adaptive and does not 

normally place an animal at risk) and 

‘‘distress’’ is the cost of the response. 

During a stress response, an animal uses 

glycogen stores that can be quickly 

replenished once the stress is alleviated. 

In such circumstances, the cost of the 

stress response would not pose serious 

fitness consequences. However, when 

an animal does not have sufficient 

energy reserves to satisfy the energetic 

costs of a stress response, energy 

resources must be diverted from other 

functions. This state of distress will last 

until the animal replenishes its 

energetic reserves sufficient to restore 

normal function. 

Relationships between these 

physiological mechanisms, animal 

behavior, and the costs of stress 

responses are well-studied through 

controlled experiments and for both 

laboratory and free-ranging animals 

(e.g., Holberton et al., 1996; Hood et al., 

1998; Jessop et al., 2003; Krausman et 

al., 2004; Lankford et al., 2005). Stress 

responses due to exposure to 

anthropogenic sounds or other stressors 

and their effects on marine mammals 

have also been reviewed (Fair and 

Becker, 2000; Romano et al., 2002b) 

and, more rarely, studied in wild 

populations (e.g., Romano et al., 2002a). 

For example, Rolland et al. (2012) found 

that noise reduction from reduced ship 

traffic in the Bay of Fundy was 

associated with decreased stress in 

North Atlantic right whales. These and 

other studies lead to a reasonable 

expectation that some marine mammals 

will experience physiological stress 

responses upon exposure to acoustic 

stressors and that it is possible that 

some of these would be classified as 

‘‘distress.’’ In addition, any animal 

experiencing TTS would likely also 

experience stress responses (NRC, 

2005), however distress is an unlikely 

result of this project based on 

observations of marine mammals during 

previous, similar construction projects 

and given the anticipated effectiveness 

of proposed mitigation measures. 

Auditory Masking—Since many 

marine mammals rely on sound to find 

prey, moderate social interactions, and 

facilitate mating (Tyack, 2008), noise 

from anthropogenic sound sources can 

interfere with these functions, but only 

if the noise spectrum overlaps with the 

hearing sensitivity of the receiving 

marine mammal (Southall et al., 2007; 

Clark et al., 2009; Hatch et al., 2012). 

Chronic exposure to excessive, though 

not high-intensity, noise could cause 

masking at particular frequencies for 

marine mammals that utilize sound for 

vital biological functions (Clark et al., 

2009). Acoustic masking is when other 

noises such as from human sources 

interfere with an animal’s ability to 

detect, recognize, or discriminate 

between acoustic signals of interest (e.g., 

those used for intraspecific 

communication and social interactions, 

prey detection, predator avoidance, 

navigation) (Richardson et al., 1995; 

Erbe et al., 2016). Therefore, under 

certain circumstances, marine mammals 

whose acoustical sensors or 

environment are being severely masked 

could also be impaired from maximizing 

their performance fitness for survival 

and reproduction. The ability of a noise 

source to mask biologically important 

sounds depends on the characteristics of 

both the noise source and the signal of 

interest (e.g., signal-to-noise ratio, 

temporal variability, direction), in 

relation to each other and to an animal’s 

hearing abilities (e.g., sensitivity, 

frequency range, critical ratios, 

frequency discrimination, directional 

discrimination, age or TTS hearing loss), 

and existing ambient noise and 

propagation conditions (Hotchkin and 

Parks, 2013). 

Under certain circumstances, marine 

mammals experiencing significant 

masking could also be impaired from 

maximizing their performance fitness in 

survival and reproduction. Therefore, 

when the coincident (masking) sound is 

human-made, it may be considered 

harassment when disrupting or altering 

critical behaviors. It is important to 

distinguish TTS and PTS, which persist 

after the sound exposure, from masking, 

which occurs during the sound 

exposure. Because masking (without 

resulting in TS) is not associated with 

abnormal physiological function, it is 

not considered a physiological effect, 

but rather a potential behavioral effect. 

The frequency range of the potentially 

masking sound is important in 

determining any potential behavioral 

impacts. For example, low-frequency 

signals may have less effect on highfrequency echolocation sounds 

produced by odontocetes but are more 

likely to affect detection of mysticete 

communication calls and other 

potentially important natural sounds 

such as those produced by surf and 

some prey species. The masking of 

communication signals by 

anthropogenic noise may be considered 

as a reduction in the communication 

space of animals (e.g., Clark et al., 2009) 

and may result in energetic or other 

costs as animals change their 

vocalization behavior (e.g., Miller et al., 

2000; Foote et al., 2004; Parks et al., 

2007; Di Iorio and Clark, 2010; Holt et 

al., 2009). Masking can be reduced in 

situations where the signal and noise 

come from different directions 

(Richardson et al., 1995), through 

amplitude modulation of the signal, or 


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through other compensatory behaviors 

(Hotchkin and Parks, 2013). Masking 

can be tested directly in captive species 

(e.g., Erbe, 2008), but in wild 

populations it must be either modeled 

or inferred from evidence of masking 

compensation. There are few studies 

addressing real-world masking sounds 

likely to be experienced by marine 

mammals in the wild (e.g., Branstetter et 

al., 2013). 

Marine mammals at or near the 

project site may be exposed to 

anthropogenic noise which may lead to 

some habituation, but is also a source of 

masking. Vocalization changes may 

result from a need to compete with an 

increase in background noise and 

include increasing the source level, 

modifying the frequency, increasing the 

call repetition rate of vocalizations, or 

ceasing to vocalize in the presence of 

increased noise (Hotchkin and Parks, 

2013). 

Masking is more likely to occur in the 

presence of broadband, relatively 

continuous noise sources. Energy 

distribution of pile driving covers a 

broad frequency spectrum, and sound 

from pile driving would be within the 

audible range of marine mammals. 

While some construction during 

Columbia Gulf’s activities may mask 

some acoustic signals that are relevant 

to the daily behavior of BBES dolphins 

if they are in the vicinity of the project, 

the short-term duration and limited 

areas affected make it very unlikely that 

reproductive success or survival of 

individual animals would be affected. 

Water quality—Temporary and 

localized reduction in water quality will 

occur as a result of in-water 

construction activities. The installation 

of piles and proposed dredging for 

pipeline installation will disturb bottom 

sediments and will cause a temporary 

increase in suspended sediment in the 

project area. In general, turbidity 

associated with pile driving is localized 

to about a 25-ft (7.6m) radius around the 

pile (Everitt et al. 1980). The small 

resulting sediment plume is expected to 

settle out of the water column within a 

few hours. Studies of the effects of 

turbid water on fish (marine mammal 

prey) suggest that concentrations of 

suspended sediment can reach 

thousands of milligrams per liter before 

an acute toxic reaction is expected 

(Burton, 1993). 

Effects from project-related turbidity 

and sedimentation are expected to be 

short-term, minor, and localized. 

Following the completion of sedimentdisturbing activities, suspended 

sediments in the water column are 

expected to dissipate and return to 

background levels. In general, turbidity 

within the water column can contribute 

to reduced oxygen levels in the water 

and can irritate the gills of prey fish 

species in the proposed project area. 

However, turbidity plumes associated 

with the project would be temporary 

and localized, and fish in the proposed 

project area would be able to move away 

from and avoid the areas where plumes 

may occur. Therefore, it is expected that 

the impacts on prey fish species from 

turbidity, and therefore on marine 

mammals, would be minimal and 

temporary. In general, the area that may 

be impacted by the proposed 

construction activities is relatively small 

compared to the available marine 

mammal habitat in Barataria Bay. 

In addition to sediment, due to the 

natural and human history of Barataria 

bay, work that disturbs the substrate 

could encounter residual, undetected 

petroleum material deposited as a result 

of naturally occurring seeps or that 

resulted from past extraction activities. 

The most likely location for 

encountering such material is in at the 

coastline and within or proximate to the 

intertidal zone. Columbia Gulf will take 

all appropriate precautions to prevent 

the resuspension of contaminated media 

and will notify all appropriate 

authorities if weathered oil is 

encountered during construction 

activities 

Potential Effects on Prey—Sound may 

affect marine mammals through impacts 

on the abundance, behavior, or 

distribution of prey species (e.g., 

crustaceans, cephalopods, fishes, 

zooplankton). Marine mammal prey 

varies by species, season, and location 

and, for some, is not well documented. 

Studies regarding the effects of noise on 

known marine mammal prey are 

described here. 

Fishes utilize the soundscape and 

components of sound in their 

environment to perform important 

functions such as foraging, predator 

avoidance, mating, and spawning (e.g., 

Zelick et al., 1999; Fay, 2009). 

Depending on their hearing anatomy 

and peripheral sensory structures, 

which vary among species, fishes hear 

sounds using pressure and particle 

motion sensitivity capabilities and 

detect the motion of surrounding water 

(Fay et al., 2008). The potential effects 

of noise on fishes depends on the 

overlapping frequency range, distance 

from the sound source, water depth of 

exposure, and species-specific hearing 

sensitivity, anatomy, and physiology. 

Key impacts to fishes may include 

behavioral responses, hearing damage, 

barotrauma (pressure-related injuries), 

and mortality. 

Fish react to sounds that are 

especially strong and/or intermittent 

low-frequency sounds. Short duration, 

sharp sounds can cause overt or subtle 

changes in fish behavior and local 

distribution. The reaction of fish to 

noise depends on the physiological 

condition of the fish, past exposures, 

motivation (e.g., feeding, spawning, 

migration), and other environmental 

factors. (Hastings and Popper, 2005) 

identified several studies that suggest 

fish may relocate to avoid certain areas 

of sound energy. Additional studies 

have documented effects of pile driving 

on fishes (e.g. Scholik and Yan, 2001; 

2002; Popper and Hastings, 2009). 

Several studies have demonstrated that 

impulse sounds might affect the 

distribution and behavior of some 

fishes, potentially impacting foraging 

opportunities or increasing energetic 

costs (e.g., Fewtrell and McCauley, 

2012; Pearson et al., 1992; Skalski et al., 

1992; Santulli et al., 1999; Paxton et al., 

2017). However, some studies have 

shown no or slight reaction to impulse 

sounds (e.g., Pen ̃ a et al., 2013; Wardle 

et al., 2001; Jorgenson and Gyselman, 

2009; Cott et al., 2012. More commonly, 

though, the impacts of noise on fishes 

are temporary. 

SPLs of sufficient strength have been 

known to cause injury to fishes and fish 

mortality (summarized in Popper et al. 

(2014)). However, in most fish species, 

hair cells in the ear continuously 

regenerate and loss of auditory function 

likely is restored when damaged cells 

are replaced with new cells. Halvorsen 

et al. (2012b) showed that a TTS of 4– 

6 dB was recoverable within 24 hours 

for one species. Impacts would be most 

severe when the individual fish is close 

to the source and when the duration of 

exposure is long. Injury caused by 

barotrauma can range from slight to 

severe and can cause death, and is most 

likely for fish with swim bladders. 

Barotrauma injuries have been 

documented during controlled exposure 

to impact pile driving (Halvorsen et al., 

2012a; Casper et al., 2013; Casper et al., 

2017). 

Fish populations in the proposed 

project area that serve as marine 

mammal prey could be temporarily 

affected by noise from pile installation. 

The frequency range in which fishes 

generally perceive underwater sounds is 

50 to 2,000 Hz, with peak sensitivities 

below 800 Hz (Popper and Hastings, 

2009). Fish behavior or distribution may 

change, especially with strong and/or 

intermittent sounds that could harm 

fishes. High underwater SPLs have been 

documented to alter behavior, cause 

hearing loss, and injure or kill 

individual fish by causing serious 


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internal injury (Hastings and Popper, 

2005). 

The greatest potential impact to fishes 

during construction would occur during 

impact pile driving. In-water 

construction activities would only occur 

during daylight hours, allowing fish to 

forage and transit the project area in the 

evening. In general, impacts on marine 

mammal prey species are expected to be 

minor and temporary. 

Potential Effects on Foraging 

Habitat—The proposed activities would 

not result in permanent impacts to 

habitats used directly by marine 

mammals. The total seafloor area 

affected by the project during 

construction is estimated to be 2.79 

acres, of which .02 acres would be 

permanently altered. This alteration 

represents a small portion of the 

foraging area available to marine 

mammals outside this project vicinity 

and in broader Barataria Bay. 

Construction would have minimal 

impacts on invertebrate species 

(principally shrimp), which have been 

identified as target prey of BBES 

dolphins (Bowens-Stevens, 2021). 

Barataria Bay is designated as essential 

fish habitat for several species, some of 

which serve as prey for BBES dolphins. 

However, given the short daily duration 

of sound associated with individual pile 

driving and the relatively small areas 

being affected, pile driving associated 

with the project is not likely to have a 

permanent adverse effect on any fish 

habitat, or populations of fish species. 

Also, the area impacted by the project 

is relatively small compared to the 

available habitat just outside the project 

area. Therefore, impacts of the project 

are not likely to have adverse effects on 

marine mammal foraging habitat in the 

proposed project area. 

In summary for this project, serious 

injuries to or mortality of BBES 

dolphins are not anticipated as a result 

of shore side activities or in-water 

construction for the project and neither, 

as described in greater detail in the 

Estimated Take section, is PTS (Level A 

harassment). However, behavioral 

impacts could occur due to the increase 

in underwater noise resulting from pile 

driving activities. Potential acoustic 

disturbance originating from the 

specified activities considered here is 

expected to be of a relatively short 

duration, likely in the form of avoidance 

of the area while activities are being 

conducted. Pile driving is proposed to 

take place from 7 a.m. to 7 p.m. 

(adjusted as appropriate to conduct 

work during daylight hours), and may 

occur on any day of the week for 

approximately 25 days of in-water work. 

Bottlenose dolphins are expected to 

avoid the project area during pile 

driving activities, though dolphins 

could be present when pile driving 

begins. Columbia Gulf proposes to 

implement mitigation measures such as 

pre-clearance monitoring and adherence 

to a soft-start protocol in order to 

mitigate against adverse impacts to 

dolphins that may be in the area when 

work commences or is restarted. 

Sufficient monitoring will be 

maintained in order to detect marine 

mammals in the area and implement 

any necessary response including work 

stoppage, should it become necessary. 

The specified activity could cause 

localized impacts to dolphin prey, but is 

otherwise unlikely to affect habitat. 

While some injury or loss of prey 

animals may occur, fish are expected to 

avoid the project area during pile 

driving activities and changes in 

abundance of prey are not expected. 

Estimated Take of Marine Mammals 

This section provides an estimate of 

the number of incidental takes proposed 

for authorization through this IHA, 

which will inform both NMFS’ 

consideration of ‘‘small numbers,’’ and 

the negligible impact determinations. 

Harassment is the only type of take 

expected to result from these activities. 

Except with respect to certain activities 

not pertinent here, section 3(18) of the 

MMPA defines ‘‘harassment’’ as any act 

of pursuit, torment, or annoyance, 

which (i) has the potential to injure a 

marine mammal or marine mammal 

stock in the wild (Level A harassment); 

or (ii) has the potential to disturb a 

marine mammal or marine mammal 

stock in the wild by causing disruption 

of behavioral patterns, including, but 

not limited to, migration, breathing, 

nursing, breeding, feeding, or sheltering 

(Level B harassment). 

Authorized takes would be by Level B 

harassment only, in the form of 

disruption of behavioral patterns for 

individual marine mammals resulting 

from exposure to sound emanated from 

pile driving activity. Based on the 

nature of the activity and the 

anticipated effectiveness of the 

mitigation measures including the 

utilization of Protected Species 

Observers to monitor for marine 

mammals and implementation of preclearance and soft start protocols 

discussed in detail below in the 

Proposed Mitigation section, Level A 

harassment is neither anticipated nor 

proposed to be authorized. 

As described previously, no serious 

injury or mortality is anticipated or 

proposed to be authorized for this 

activity. Below we describe how the 

proposed take numbers are estimated. 

For acoustic impacts, generally 

speaking, we estimate take by 

considering: (1) acoustic thresholds 

above which NMFS believes the best 

available science indicates marine 

mammals will be behaviorally harassed 

or incur some degree of permanent 

hearing impairment for example, 

permanent threshold shift (or PTS); (2) 

the area or volume of water that will be 

ensonified above these levels in a day; 

(3) the density or occurrence of marine 

mammals within these ensonified areas; 

and, (4) the number of days of activities. 

We note that while these factors can 

contribute to a basic calculation to 

provide an initial prediction of potential 

takes, additional information that can 

qualitatively inform take estimates is 

also sometimes available (e.g., previous 

monitoring results or average group 

size). Below, we describe the factors 

considered here in more detail and 

present the proposed take estimates. 

Acoustic Thresholds 

NMFS recommends the use of 

acoustic thresholds that identify the 

received level of underwater sound 

above which exposed marine mammals 

would be reasonably expected to be 

behaviorally harassed (equated to Level 

B harassment) or to incur PTS of some 

degree (equated to Level A harassment). 

Level B Harassment—Though 

significantly driven by received level, 

the onset of behavioral disturbance from 

anthropogenic noise exposure is also 

informed to varying degrees by other 

factors related to the source or exposure 

context (e.g., frequency, predictability, 

duty cycle, duration of the exposure, 

signal-to-noise ratio, distance to the 

source), the environment (e.g., 

bathymetry, other noises in the area, 

predators in the area), and the receiving 

animals (hearing, motivation, 

experience, demography, life stage, 

depth) and can be difficult to predict 

(e.g., Southall et al., 2007, 2021, Ellison 

et al., 2012). Based on what the 

available science indicates and the 

practical need to use a threshold based 

on a metric that is both predictable and 

measurable for most activities, NMFS 

typically uses a generalized acoustic 

threshold based on received level to 

estimate the onset of behavioral 

harassment. NMFS generally predicts 

that marine mammals are likely to be 

behaviorally harassed in a manner 

considered to be Level B harassment 

when exposed to underwater 

anthropogenic noise above root-meansquared pressure received levels (RMS 

SPL) of 120 dB (referenced to 1 

micropascal (re 1 mPa)) for continuous 

(e.g., vibratory pile driving, drilling) and 

above RMS SPL 160 dB re 1 mPa for nonVerDate Sep<11>2014 19:19 Sep 06, 2023 Jkt 259001 PO 00000 Frm 00045 Fmt 4703 Sfmt 4703 E:\FR\FM\07SEN1.SGM 07SEN1

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explosive impulsive (e.g., seismic 

airguns) or intermittent (e.g., scientific 

sonar) sources. Generally speaking, 

Level B harassment take estimates based 

on these behavioral harassment 

thresholds are expected to include any 

likely takes by Temporary Threshold 

Shift (TTS) as, in most cases, the 

likelihood of TTS occurs at distances 

from the source less than those at which 

behavioral harassment is likely. TTS of 

a sufficient degree can manifest as 

behavioral harassment, as reduced 

hearing sensitivity and the potential 

reduced opportunities to detect 

important signals (conspecific 

communication, predators, prey) may 

result in changes in behavior that would 

not otherwise occur. 

Columbia Gulf’s Request for 

Authorization includes actions known 

to generate impulsive sound (impact 

pile driving) that may cause incidental 

harassment, and therefore the RMS SPL 

threshold of 160 re 1 mPa is applicable. 

Level A harassment—NMFS’ 

Technical Guidance for Assessing the 

Effects of Anthropogenic Sound on 

Marine Mammal Hearing (Version 2.0) 

(Technical Guidance, 2018) identifies 

dual criteria to assess auditory injury 

(Level A harassment) to five different 

marine mammal groups (based on 

hearing sensitivity) as a result of 

exposure to noise from two different 

types of sources (impulsive or nonimpulsive). The specified activity 

proposed by Columbia Gulf includes the 

use of an impulsive source type and is 

proposed to occur in an area where 

BBES bottlenose dolphins, a midfrequency cetacean, are found. 

These thresholds are provided in the 

table below. The references, analysis, 

and methodology used in the 

development of the thresholds are 

described in NMFS’ 2018 Technical 

Guidance, available at: https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/marinemammal-acoustic-technical-guidance. 

TABLE 5—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT

Hearing group 

PTS onset acoustic thresholds * 

(Received Level) 

Impulsive Non-impulsive 

Low-Frequency (LF) Cetaceans .................................................... Cell 1 Lpk,flat: 219 dB LE,LF,24h: 183 dB ........................................ Cell 2 LE,LF,24h: 199 dB 

Mid-Frequency (MF) Cetaceans ................................................... Cell 3 Lpk,flat: 230 dB LE,MF,24h: 185 dB ....................................... Cell 4 LE,MF,24h: 198 dB 

High-Frequency (HF) Cetaceans .................................................. Cell 5 Lpk,flat: 202 dB LE,HF,24h: 155 dB ........................................ Cell 6 LE,HF,24h: 173 dB 

Phocid Pinnipeds (PW) (Underwater) ........................................... Cell 7 Lpk,flat: 218 dB LE,PW,24h: 185 dB ....................................... Cell 8 LE,PW,24h: 201 dB 

Otariid Pinnipeds (OW) (Underwater) ........................................... Cell 9 Lpk,flat: 232 dB LE,OW,24h: 203 dB ....................................... Cell 10 LE,OW,24h: 219 dB 

* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should also be considered. 

Note: Peak sound pressure (Lpk) has a reference value of 1 μPa, and cumulative sound exposure level (LE) has a reference value of 1μPa2s. In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ‘‘flat’’ is being included to indicate peak sound pressure should be flat 

weighted or unweighted within the generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The 

cumulative sound exposure level thresholds could be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it is 

valuable for action proponents to indicate the conditions under which these acoustic thresholds will be exceeded. 

Ensonified Area 

Here, we describe operational and 

environmental parameters of the activity 

that are used in estimating the area that 

may be ensonified to levels above the 

acoustic thresholds, including source 

levels and transmission loss coefficient. 

To calculate the ensonified area, 

Columbia Gulf used the NMFS User 

Spreadsheet and accompanying 2018 

guidance. Columbia Gulf located data 

for impact installation of a 36 inch 

concrete pile (McGillvary, 2007), 

measured at 50 meters, to serve as a 

suitable proxy source level for the 104 

36-inch spun-cast piles selected for the 

project (see Table 6). The applicant then 

elected to apply the source levels for the 

36-in proxy pile to all piles being 

driven, including the 20 18-inch piles, 

likely resulting in an overestimate of 

resulting noise from these smaller piles. 

Transmission loss (TL) is the decrease 

in acoustic intensity as an acoustic 

pressure wave propagates out from a 

source. TL parameters vary with 

frequency, temperature, sea conditions, 

current, source and receiver depth, 

water depth, water chemistry and 

bottom composition and topography. 

The general formula for underwater TL 

is: 

TL = B * Log10 (R1/R2), where: 

TL = Transmission loss in dB, 

B = Transmission loss coefficient, 

R1 = the distance of the modeled SPL from 

the driving pile, and 

R2 = the distance from the driven pile of the 

initial measurement. 

Absent site-specific acoustical 

monitoring with differing measured 

transmission loss, a practical spreading 

value of 15 is used as the transmission 

loss coefficient. Site-specific 

transmission loss data for the project 

area in Barataria Bay is not available; 

therefore, the default coefficient of 15 is 

used to determine the distances to the 

Level A harassment and Level B 

harassment thresholds. The ensonified 

area associated with Level A harassment 

is more technically challenging to 

predict due to the need to account for 

a duration component. There, NMFS 

developed an optional User Spreadsheet 

and accompanying Technical Guidance 

that can be used to relatively simply 

predict an isopleth distance for use in 

conjunction with marine mammal 

density or occurrence to help predict 

potential takes. We note that because of 

some of the assumptions included in the 

methods underlying the optional tool, 

we anticipate that the resulting isopleth 

estimates are typically going to be 

overestimates of some degree, which 

may result in an overestimate of 

potential Level A harassment. However, 

this optional tool offers the best way to 

estimate isopleth distances when more 

sophisticated modeling methods are not 

available or practical. For stationary 

sources such as pile driving, the options 

User Spreadsheet tool predicts the 

distance at which, if a marine mammal 

remained at that distance for the 

duration of the activity, it would be 

expected to incur PTS. Inputs used in 

the option User Spresheet tool, and the 

resulting estimated isopleths, are 

reported in Tables 6 and 7, below. The 

applicant as applied a 15LogR 

propagation loss rate in the User 

Spreadsheet, and included a 5 dB 

attenuation factor for proposed use of a 

bubble curtain which is consistent with 

NMFS guidelines. 


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TABLE 6—PROXY PILE CHARACTERISTICS (USER SPREADSHEET INPUT) 

Pile type 

SLs Measured 

distance Source 

dB Peak dB rms dB SEL 

36’’ concrete pile, Impact pile 

driven (5 dB attenuated).

186 174 160 50 meters .................................. MacGillivary, 2007. 

To calculate the harassment zones, 

Columbia Gulf identified a 

representative location in the center of 

the Tie-in Facility and second 

representative location in the center of 

the POD Meter Station and used these 

locations to calculate the harassment 

zones for each site. Given the close 

proximity of individual piles to one 

another, NMFS concurred with this 

approach. Columbia Gulf then accessed 

the User Spreadsheet to calculate the 

distance from each of the two 

representative pile driving locations to 

the furthest extent of Level A and Level 

B thresholds for mid-frequency 

cetaceans. In order to ensure 

conservative results, the source level 

data for 36 inch piles was used as a 

proxy for all pile driving activities, 

including installation of smaller 

diameter piles. 

TABLE 7—HARASSMENT ZONE ISOPLETHS ATTRIBUTABLE TO PROPOSED PILE DRIVING

Activity 

Distance from representative sound source 

PTS: Level A harassment zone 

(mid-frequency 

cetaceans) 

Behavioral disturbance: Level B harassment 

zone 

(all marine mammals) 

Impact pile driving in Barataria Bay a ................ 142.0 feet ......................................................... 1,407.0 feet. 

a User Spreadsheet output based on installation by impact hammer of (proxy) 36-inch-diameter concrete piles, and use of bubble curtains (estimated 5 dB reduction, per consultations with NMFS) (MacGillivray et al., 2007). 

Based on the user spreadsheet outputs 

reflected in Table 5, the Level B 

harassment zone would have a radius of 

approximately 1,407.0 feet (428.9 

meters) from the source pile, or an 

approximate area of 0.58 square 

kilometers (km2). The Level A zone 

would have a calculated radius of 

approximately 142.0 feet (43.2 meters), 

or an approximate area of 63,347 square 

feet (0.006 km2). Columbia Gulf plans to 

implement a 50 meter shutdown zone 

that extends coverage beyond the 43.2 

meter Level A harassment zone 

indicated by the User Spreadsheet. As a 

result, given that detection of bottlenose 

dolphins within this distance is 

expected to be successful, no Level A 

take is anticipated to occur, or proposed 

to be authorized, as a result of project 

activities. 

Marine Mammal Occurrence 

In order to estimate the distribution 

and density of BBES dolphins that may 

occur in the area affected by the 

specified activity, we turn to prior areaspecific surveys and studies conducted 

in the Bay. 

Density estimates for Columbia Gulf’s 

proposal reference the findings of the 

2017 McDonald (et al.) study and an 

average of the calculated densities for 

each habitat region defined within the 

study area. Density estimates for 

bottlenose dolphins within Barataria 

Bay were derived from estimates 

calculated through vessel-based capturemark-recapture photo-ID surveys 

conducted during ten survey sessions 

from June 2010 to May 2014 (McDonald 

et.al., 2017). Because the surveys were 

conducted during the DWH oil spill, the 

resulting density estimate does not 

account for mortality following the spill. 

The study was conducted from June 

2010 to May 2014 and utilized vesselbased capture-mark-recapture photo ID 

surveys. The study area for these 

surveys included Barataria Bay and 

Pass, Bayou Rigaud, Caminada Bay and 

Pass, Barataria Waterway, and Bay des 

Ilettes. Densities varied in different 

areas within broader Barataria Bay, and 

the study area was divided into three 

(East, West, and Island) habitat regions 

to capture these observed density 

variations. Results were parsed and 

densities were calculated for each 

habitat region. Project activities may 

have some effect on both the East and 

West habitat regions, with estimated 

densities of 0.601 individuals per km2

and 1.24 individuals per km2, 

respectively. Study results indicate 

density of 11.4 individuals per km2 for 

the Island region. Given uncertainties 

regarding fidelity to and transiting 

among habitat regions, the average 

densities for each habitat region in the 

study area are then averaged together to 

create an estimated density for the 

project area. NMFS concurs with this 

approach. Inclusion of the higher 

estimated density from the Island 

habitat region results in a cumulative 

average higher than the estimated 

density for the East and West habitat 

regions alone, and reflects a 

conservative approach. Based on this 

calculation and using the best available 

information for estimating density given 

the project type and location, the 

average bottlenose dolphin density for 

the project is estimated to be 2.83 

individuals per km2. 

Take Estimation 

Here we describe how the information 

provided above is synthesized to 

produce a quantitative estimate of the 

take that is reasonably likely to occur 

and proposed for authorization. 


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TABLE 8—LEVEL B HARASSMENT TAKES REQUESTED AND PERCENTAGE OF STOCK POTENTIALLY AFFECTED

Pile driving location Species Estimated density 

Level B 

harassment area 

Level B takes 

requested 

(individuals) 

Stock 

abundance 

(individuals) 

Percentage 

(%) of stock 

potentially 

affected by 

Level B take 

Tie-In Facility ........................... Bottlenose Dolphin 2.83 

individuals per km2 .................

0.58 km2 40 2,071 1.93 

POD Meter Station .................. 2 ............................................. 0.10.

Project Totals ................... 42 ........................................... — ............................................ 2.03

Level B Take estimates for pile 

driving activities were calculated using 

the density estimate described above, 

averaging across the three areas in 

Barataria Bay. The Level B harassment 

zone is calculated using source level 

data for 36-inch concrete piles 

(including use of bubble curtains) and 

assumes an even distribution of animals 

throughout the affected area. Initial 

Level B take estimates for Tie-in Facility 

and POD Meter Station pile driving 

activity were calculated using the area 

of the Level B harassment zone (0.58 

km2) multiplied by the calculated 

density (2.83 individuals per km2). This 

results in a daily take estimate of 1.64 

individuals for pile driving at the Tiein Facility and the POD Meter Station. 

The daily Level B harassment estimate 

(1.64 individuals) was then multiplied 

by the number of days when pile 

driving will take place (24 days at the 

Tie-in Facility and 1 day at the POD 

Meter Station) to calculate the number 

of requested takes for pile driving 

related to the Project. The estimated 

takes are indicated in Table 8. 

Level A harassment is not anticipated 

to occur and authorization of Level A 

take is not requested. In-water 

construction activities will be 

completed within one to two months (a 

total of 25 to 42 days) and are not 

expected to result in serious injury or 

mortality to marine mammals within 

Barataria Bay. Based on calculated 

threshold distances in Table 7 for midfrequency cetaceans, an individual 

would need to remain within 142.0 feet 

of the piles being driven throughout the 

entire day of pile driving activities for 

cumulative exposure injury to occur. 

Given the mobility of bottlenose 

dolphins and the expected behavior of 

the species to avoid noise disturbance 

(i.e., pile driving), such a scenario is 

extremely unlikely to occur. 

Proposed Mitigation 

In order to issue an IHA under section 

101(a)(5)(D) of the MMPA, NMFS must 

set forth the permissible methods of 

taking pursuant to the activity, and 

other means of effecting the least 

practicable impact on the species or 

stock and its habitat, paying particular 

attention to rookeries, mating grounds, 

and areas of similar significance, and on 

the availability of the species or stock 

for taking for certain subsistence uses 

(latter not applicable for this action). 

NMFS regulations require applicants for 

incidental take authorizations to include 

information about the availability and 

feasibility (economic and technological) 

of equipment, methods, and manner of 

conducting the activity or other means 

of effecting the least practicable adverse 

impact upon the affected species or 

stocks, and their habitat (50 CFR 

216.104(a)(11)). 

In evaluating how mitigation may or 

may not be appropriate to ensure the 

least practicable adverse impact on 

species or stocks and their habitat, as 

well as subsistence uses where 

applicable, NMFS considers two 

primary factors: 

(1) The manner in which, and the 

degree to which, the successful 

implementation of the measure(s) is 

expected to reduce impacts to marine 

mammals, marine mammal species or 

stocks, and their habitat. This considers 

the nature of the potential adverse 

impact being mitigated (likelihood, 

scope, range). It further considers the 

likelihood that the measure will be 

effective if implemented (probability of 

accomplishing the mitigating result if 

implemented as planned), the 

likelihood of effective implementation 

(probability implemented as planned), 

and; 

(2) The practicability of the measures 

for applicant implementation, which 

may consider such things as cost, 

impact on operations. 

Mitigation for Marine Mammals and 

Their Habitat 

Columbia Gulf will retain and deploy 

qualified Protected Species Observers to 

ensure that dolphins are not present 

within 1,407.0 feet (428.8 meters) of the 

pile driving area when pile driving 

activities begin. If dolphins are observed 

entering the area in which the injury 

threshold will be exceeded (i.e., Level 

A, calculated to be 142.0 feet [43.2 

meters] and established at 50 meters), 

pile driving will cease until they leave 

the area. All vessels engaged in 

construction and crew transport will 

adhere to NMFS’s Vessel Strike 

Avoidance Measures and to related 

reporting requirements for mariners. 

Through the implementation of these 

measures and those that follow, 

Columbia Gulf will ensure that dolphins 

and other marine mammals are not 

present within an area where Level A 

harassment could occur. 

Columbia Gulf proposes the following 

additional mitigation measures: 

• Establishment and monitoring of 

Pre-clearance zones to survey for 

presence of marine mammals prior to 

commencement/resumption of work. 

• Implementation of soft start 

protocols to ensure initial sound 

stimulus is not at a harmful level. 

• Adoption of a conservative 50 meter 

shutdown zone to preclude Level A 

take. 

• Positioning of Protected Species 

Observers authorized to direct work 

stoppage if circumstances warrant. 

• Deployment of a submerged bubble 

curtain to dampen sound from impact 

driving. 

• Work stoppage should any marine 

mammal take not permitted by the IHA 

occur followed by reporting to NOAA 

Fisheries as soon as practicable and 

within 24 hours. 

Based on our evaluation of the 

applicant’s proposed measures, NMFS 

has preliminarily determined that the 

proposed mitigation measures provide 

the means of effecting the least 

practicable impact to BBES bottlenose 

dolphins and their habitat. 

Proposed Monitoring and Reporting 

In order to issue an IHA for an 

activity, section 101(a)(5)(D) of the 

MMPA states that NMFS must set forth 

requirements pertaining to the 

monitoring and reporting of such taking. 

The MMPA implementing regulations at 

50 CFR 216.104(a)(13) indicate that 

requests for authorizations must include 

the suggested means of accomplishing 

the necessary monitoring and reporting 

that will result in increased knowledge 

of the species and of the level of taking 

or impacts on populations of marine 

mammals that are expected to be 

present while conducting the activities. 


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Effective reporting is critical both to 

compliance as well as ensuring that the 

most value is obtained from the required 

monitoring. Monitoring and reporting 

requirements prescribed by NMFS 

should contribute to improved 

understanding of one or more of the 

following: 

• Occurrence of marine mammal 

species or stocks in the area in which 

take is anticipated (e.g., presence, 

abundance, distribution, density); 

• Nature, scope, or context of likely 

marine mammal exposure to potential 

stressors/impacts (individual or 

cumulative, acute or chronic), through 

better understanding of: (1) action or 

environment (e.g., source 

characterization, propagation, ambient 

noise); (2) affected species (e.g., life 

history, dive patterns); (3) co-occurrence 

of marine mammal species with the 

activity; or (4) biological or behavioral 

context of exposure (e.g., age, calving or 

feeding areas); 

• Individual marine mammal 

responses (behavioral or physiological) 

to acoustic stressors (acute, chronic, or 

cumulative), other stressors, or 

cumulative impacts from multiple 

stressors; 

• How anticipated responses to 

stressors impact either: (1) long-term 

fitness and survival of individual 

marine mammals; or (2) populations, 

species, or stocks; 

• Effects on marine mammal habitat 

(e.g., marine mammal prey species, 

acoustic habitat, or other important 

physical components of marine 

mammal habitat); and, 

• Mitigation and monitoring 

effectiveness. 

Below is a summary of the monitoring 

measures included in the application 

and proposed for pile installation 

activities associated with the Project 

(see the draft IHA for additional detail): 

• At least one NOAA Fisheriesapproved observers (i.e., Protected 

Species Observers [PSOs]) will be on 

duty and assigned to the highest 

possible vantage point in order to 

maintain a 360-degree view of the 

project area. 

• A 1,407.0 feet (428.8 meters) preclearance zone for marine mammals will 

be established using range finding 

equipment and monitored by the PSOs. 

• Observers will monitor the NOAAapproved 50 meter shutdown zone 

during all pile installation activities. 

• Observers will maintain a 

continuous watch while pile driving 

activities are under way, using 

binoculars and/or naked eye 

observations to continuously search for 

marine mammals. 

• If marine mammals are observed in 

the Project area, the sighting will be 

fully documented, including the 

following (among others), when 

possible: 

Æ Bearing to animal relative to 

observer position; 

Æ Number of individuals observed; 

Æ Estimated location within the 

Project area; 

Æ Type of construction activity (i.e., 

impact pile driving); and 

• Behavioral state, possible reaction 

of the animal(s) to the pile driving, and 

any behaviors of the animal/s while in 

the Project area.Observers will make 

note of the state of Barataria Bay using 

the Beaufort scale and collect and 

record weather conditions during the 

course of marine mammal monitoring. 

Proposed Reporting 

Columbia Gulf would provide the 

NOAA Fisheries Service with a draft 

comprehensive monitoring report 

within 90 days of the conclusion of 

monitoring. This report would include 

the following (please see draft IHA for 

additional detail): 

• A summary of the Project activity 

(e.g., Project actions, dates, times, 

durations, and locations) 

• A summary of mitigation 

implementation 

• Monitoring results and a summary 

that addresses the goals of the 

monitoring plan, including (but not 

limited to): 

Æ Environmental conditions when 

observations were made (e.g., water 

conditions and weather); 

Æ Date and time of observations 

(initiation and termination); 

Æ Date, time, number, species, and 

any other relevant data regarding marine 

mammals observed; 

Æ Description of the observed 

behaviors; and 

Æ Assessment of implementation and 

effectiveness of prescribed mitigation 

and monitoring measures. 

Negligible Impact Analysis and 

Determination 

NMFS has defined negligible impact 

as an impact resulting from the 

specified activity that cannot be 

reasonably expected to, and is not 

reasonably likely to, adversely affect the 

species or stock through effects on 

annual rates of recruitment or survival 

(50 CFR 216.103). A negligible impact 

finding is based on the lack of likely 

adverse effects on annual rates of 

recruitment or survival (i.e., populationlevel effects). An estimate of the number 

of takes alone is not enough information 

on which to base an impact 

determination. In addition to 

considering estimates of the number of 

marine mammals that might be ‘‘taken’’ 

through harassment, NMFS considers 

other factors, such as the likely nature 

of any impacts or responses (e.g., 

intensity, duration), the context of any 

impacts or responses (e.g., critical 

reproductive time or location, foraging 

impacts affecting energetics), as well as 

effects on habitat, and the likely 

effectiveness of the mitigation. We also 

assess the number, intensity, and 

context of estimated takes by evaluating 

this information relative to population 

status. Consistent with the 1989 

preamble for NMFS’ implementing 

regulations (54 FR 40338, September 29, 

1989), the impacts from other past and 

ongoing anthropogenic activities are 

incorporated into this analysis via their 

impacts on the baseline (e.g., as 

reflected in the regulatory status of the 

species, population size and growth rate 

where known, ongoing sources of 

human-caused mortality, or ambient 

noise levels). 

The BBES stock of bottlenose 

dolphins is considered a strategic stock 

because mortality attributable to human 

activity is thought to exceed PBR. 

Potential effects of this project on BBES 

dolphins include behavioral 

modification resulting from Level B 

harassment and temporary avoidance of 

the construction area. As decribed 

above, no Level A harassment is 

expected and no authorization of Level 

A take is not proposed. Given the nature 

of the harassment, its temporary nature 

and proposed mitigation, NMFS 

anticipates impacts from the specified 

activity on individuals and the stock 

would be negligible. 

The project site is within a designated 

Biologically Important Area for Small 

and Resident Populations. The BBES 

stock is present within the area yearround. All life activities may occur 

within the designated BIA including the 

project area. The project area represents 

a small portion of available habitat and 

the BIA, and adjacent areas of open 

water within the embayment that would 

remain accessible to BBES dolphins 

throughout the construction process. 

Proper implementation of the mitigation 

measures described above support a 

finding that the impacts of Level B 

harassment would be minimized and 

likely have negligible effect on 

individual animals or the BBES 

population of bottlenose dolphins. 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from this activity are 

not expected to adversely affect BBES 

bottlenose dolphins by reducing annual 

rates of recruitment or survival: 


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• No serious injury or mortality is 

anticipated or authorized; and no 

impacts to reproductive success or 

survival of any individual animals are 

expected. 

• The required mitigation measures 

are expected to avoid any Level A 

harassment and to reduce the number 

and severity of takes by Level B 

harassment. 

• Behavioral impacts and 

displacement that may occur in 

response to pile driving, is expected to 

be limited in duration to approximately 

25 days concurrent with in-water 

construction activity. 

• The specified activities do not 

impact any known important habitat 

areas such as calving grounds or unique 

feeding areas, and alternate habitat is 

readily available. 

Based on the analysis contained 

herein of the likely effects of the 

specified activity on marine mammals 

and their habitat, and taking into 

consideration the implementation of the 

proposed monitoring and mitigation 

measures, NMFS preliminarily finds 

that the total marine mammal take from 

the proposed pile driving activity will 

have a negligible impact on BBES 

bottlenose dolphins. 

Small Numbers 

As noted previously, only take of 

small numbers of marine mammals may 

be authorized under sections 

101(a)(5)(A) and (D) of the MMPA for 

specified activities other than military 

readiness activities. The MMPA does 

not define small numbers and so, in 

practice, where estimated numbers are 

available, NMFS compares the number 

of individuals taken to the most 

appropriate estimation of abundance of 

the relevant species or stock in our 

determination of whether an 

authorization is limited to small 

numbers of marine mammals. When the 

predicted number of individuals to be 

taken is fewer than one-third of the 

species or stock abundance, the take is 

considered to be of small numbers. 

Additionally, other qualitative factors 

may be considered in the analysis, such 

as the temporal or spatial scale of the 

activities. 

Based on a conservative estimate of 

the number of takes that may occur as 

a result of pile driving activities, less 

than two percent of the BBES 

population would be subject to take via 

Level B harassment. 

Based on the analysis contained 

herein of the proposed activity 

(including the proposed mitigation and 

monitoring measures) and the 

anticipated take of marine mammals, 

NMFS preliminarily finds that small 

numbers of marine mammals would be 

taken relative to the population size of 

the affected species or stocks. 

Unmitigable Adverse Impact Analysis 

and Determination 

No subsistence uses of BBES 

bottlenose dolphins are known to occur. 

Therefore, NMFS has determined that 

the total taking of affected species or 

stocks would not have an unmitigable 

adverse impact on the availability of 

such species or stocks for taking for 

subsistence purposes. 

Endangered Species Act 

Section 7(a)(2) of the Endangered 

Species Act of 1973 (ESA; 16 U.S.C. 

1531 et seq.) requires that each Federal 

agency insure 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 

designated critical habitat. To ensure 

ESA compliance for the issuance of 

IHAs, NMFS consults internally 

whenever we propose to authorize take 

for endangered or threatened species. 

No incidental take of ESA-listed 

species is proposed under the auspices 

of this authorization. Therefore, NMFS 

has determined that formal consultation 

under section 7 of the ESA is not 

required for this action. 

Proposed Authorization 

As a result of these preliminary 

determinations, NMFS proposes to issue 

an IHA to Columbia Gulf, LLC to 

conduct the specified pile driving 

activity in Barataria Bay, Louisiana 

during the 1-year period of 

authorization, provided the previously 

mentioned mitigation, monitoring, and 

reporting requirements are incorporated. 

A draft of the proposed IHA can be 

found at: https://

www.fisheries.noaa.gov/permit/ 

incidental-take-authorizations-undermarine-mammal-protection-act. 

Request for Public Comments 

We request comment on our analyses, 

the proposed authorization, and any 

other aspect of this notice of proposed 

IHA for the specified activity. We also 

request comment on the potential 

renewal of this proposed IHA as 

described in the paragraph below. 

Please include with your comments any 

supporting data or literature citations to 

help inform decisions on the request for 

this IHA or a subsequent renewal IHA. 

On a case-by-case basis, NMFS may 

issue a one-time, 1-year renewal IHA 

following notice to the public providing 

an additional 15 days for public 

comments when (1) up to another year 

of identical or nearly identical activities 

as described in the Description of 

Proposed Activity section of this notice 

is planned or (2) the activities as 

described in the Description of 

Proposed Activity section of this notice 

would not be completed by the time the 

IHA expires and a renewal would allow 

for completion of the activities beyond 

that described in the Dates and Duration 

section of this notice, provided all of the 

following conditions are met: 

• A request for renewal is received no 

later than 60 days prior to the needed 

renewal IHA effective date (recognizing 

that the renewal IHA expiration date 

cannot extend beyond one year from 

expiration of the initial IHA). 

• The request for renewal must 

include the following: 

(1) An explanation that the activities 

to be conducted under the requested 

renewal IHA are identical to the 

activities analyzed under the initial 

IHA, are a subset of the activities, or 

include changes so minor (e.g., 

reduction in pile size) that the changes 

do not affect the previous analyses, 

mitigation and monitoring 

requirements, or take estimates (with 

the exception of reducing the type or 

amount of take). 

(2) A preliminary monitoring report 

showing the results of the required 

monitoring to date and an explanation 

showing that the monitoring results do 

not indicate impacts of a scale or nature 

not previously analyzed or authorized. 

Upon review of the request for 

renewal, the status of the affected 

species or stocks, and any other 

pertinent information, NMFS 

determines that there are no more than 

minor changes in the activities, the 

mitigation and monitoring measures 

will remain the same and appropriate, 

and the findings in the initial IHA 

remain valid. 

Dated: September 1, 2023. 

Kimberly Damon-Randall, 

Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2023–19310 Filed 9–6–23; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD323] 

Pacific Fishery Management Council; 

Public Meeting 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 


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