29872 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

50 CFR Part 218 

[Docket No. 170918908–8501–01] 

RIN 0648–BH29 

Taking and Importing Marine 

Mammals; Taking Marine Mammals 

Incidental to the U.S. Navy Training 

and Testing Activities in the HawaiiSouthern California Training and 

Testing Study Area 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Proposed rule; request for 

comments and information. 

SUMMARY: NMFS has received a request 

from the U.S. Navy (Navy) for 

authorization to take marine mammals 

incidental to the training and testing 

activities conducted in the HawaiiSouthern California Training and 

Testing (HSTT) Study Area. Pursuant to 

the Marine Mammal Protection Act 

(MMPA), NMFS is requesting comments 

on its proposal to issue regulations and 

subsequent Letters of Authorization 

(LOA) to the Navy to incidentally take 

marine mammals during the specified 

activities. NMFS will consider public 

comments prior to issuing any final rule 

and making final decisions on the 

issuance of the requested MMPA 

authorizations. Agency responses to 

public comments will be summarized in 

the final rule. The Navy’s activities 

qualify as military readiness activities 

pursuant to the MMPA, as amended by 

the National Defense Authorization Act 

for Fiscal Year 2004 (2004 NDAA). 

DATES: Comments and information must 

be received no later than August 9, 

2018. 

ADDRESSES: You may submit comments, 

identified by NOAA–NMFS–2018–0071, 

by any of the following methods: 

• Electronic submissions: Submit all 

electronic public comments via the 

Federal eRulemaking Portal, Go to 

www.regulations.gov/#!docketDetail;D=

NOAA-NMFS-2018-0071, click the 

‘‘Comment Now!’’ icon, complete the 

required fields, and enter or attach your 

comments. 

• Mail: Submit comments to Jolie 

Harrison, Chief, Permits and 

Conservation Division, Office of 

Protected Resources, National Marine 

Fisheries Service, 1315 East-West 

Highway, Silver Spring, MD 20910– 

3225. 

• Fax: (301) 713–0376; Attn: Jolie 

Harrison. 

Instructions: Comments sent by any 

other method, to any other address or 

individual, or received after the end of 

the comment period, may not be 

considered by NMFS. All comments 

received are a part of the public record 

and will generally be posted for public 

viewing on www.regulations.gov 

without change. All personal identifying 

information (e.g., name, address, etc.), 

confidential business information, or 

otherwise sensitive information 

submitted voluntarily by the sender may 

be publicly accessible. Do not submit 

Confidential Business Information or 

otherwise sensitive or protected 

information. NMFS will accept 

anonymous comments (enter ‘‘N/A’’ in 

the required fields if you wish to remain 

anonymous). Attachments to electronic 

comments will be accepted in Microsoft 

Word, Excel, or Adobe PDF file formats 

only. 

FOR FURTHER INFORMATION CONTACT: 

Stephanie Egger, Office of Protected 

Resources, NMFS; phone: (301) 427– 

8401. 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: www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

incidental-take-authorizations-militaryreadiness-activities. In case of problems 

accessing these documents, please call 

the contact listed above. 

SUPPLEMENTARY INFORMATION: 

Background 

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 issued or, if the taking is 

limited to harassment, a notice of a 

proposed authorization is provided to 

the public for review and the 

opportunity to submit comments. 

An authorization for incidental 

takings shall be granted if NMFS finds 

that the taking will have a negligible 

impact on the species or stock(s), will 

not have an unmitigable adverse impact 

on the availability of the species or 

stock(s) for subsistence uses (where 

relevant), and if the permissible 

methods of taking and requirements 

pertaining to the mitigation, monitoring 

and reporting of such takings are set 

forth. 

NMFS has defined ‘‘negligible 

impact’’ in 50 CFR 216.103 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. 

NMFS has defined ‘‘unmitigable 

adverse impact’’ in 50 CFR 216.103 as 

an impact resulting from the specified 

activity: 

(1) That is likely to reduce the 

availability of the species to a level 

insufficient for a harvest to meet 

subsistence needs by: (i) Causing the 

marine mammals to abandon or avoid 

hunting areas; (ii) directly displacing 

subsistence users; or (iii) placing 

physical barriers between the marine 

mammals and the subsistence hunters; 

and 

(2) That cannot be sufficiently 

mitigated by other measures to increase 

the availability of marine mammals to 

allow subsistence needs to be met. 

The MMPA states that the term ‘‘take’’ 

means to harass, hunt, capture, kill or 

attempt to harass, hunt, capture, or kill 

any marine mammal. 

The 2004 NDAA (Pub. L. 108–136) 

removed the ‘‘small numbers’’ and 

‘‘specified geographical region’’ 

limitations indicated above and 

amended the definition of ‘‘harassment’’ 

as it applies to a ‘‘military readiness 

activity’’ to read as follows (Section 

3(18)(B) of the MMPA): (i) Any act that 

injures or has the significant potential to 

injure a marine mammal or marine 

mammal stock in the wild (Level A 

Harassment); or (ii) Any act that 

disturbs or is likely to disturb a marine 

mammal or marine mammal stock in the 

wild by causing disruption of natural 

behavioral patterns, including, but not 

limited to, migration, surfacing, nursing, 

breeding, feeding, or sheltering, to a 

point where such behavioral patterns 

are abandoned or significantly altered 

(Level B Harassment). 

Summary of Request 

On September 13, 2017, NMFS 

received an application from the Navy 

requesting incidental take regulations 

and two LOAs to take individuals of 39 

marine mammal species by Level A and 

B harassment incidental to training and 

testing activities (categorized as military 

readiness activities) from the use of 

sonar and other transducers, in-water 

detonations, air guns, and impact pile 

driving/vibratory extraction in the 

HSTT Study Area over five years. In 

addition, the Navy is requesting 

incidental take authorization by serious 

injury or mortality of ten takes of two 

species due to explosives and for up to 

three takes of large whales from vessel 


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strikes over the five-year period. The 

Navy’s training and testing activities 

would occur over five years beginning 

in December 2018. On October 13, 2017, 

the Navy sent an amendment to its 

application and Navy’s rulemaking/LOA 

application was considered final and 

complete. 

The Navy requests two five-year 

LOAs, one for training and one for 

testing activities to be conducted within 

the HSTT Study Area (which extends 

from the north-central Pacific Ocean, 

from the mean high tide line in 

Southern California west to Hawaii and 

the International Date Line), including 

the Hawaii and Southern California 

(SOCAL) Range Complexes, as well as 

the Silver Strand Training Complex and 

overlapping a small portion of the Point 

Mugu Sea Range. The Hawaii Range 

Complex encompasses ocean areas 

around the Hawaiian Islands, extending 

from 16 degrees north latitude to 43 

degrees north latitude and from 150 

degrees west longitude to the 

International Date Line. The SOCAL 

Range Complex is located 

approximately between Dana Point and 

San Diego, California, and extends 

southwest into the Pacific Ocean and 

also includes a small portion of the 

Point Mugu Sea Range. The Silver 

Strand Training Complex is an 

integrated set of training areas located 

on and adjacent to the Silver Strand, a 

narrow, sandy isthmus separating the 

San Diego Bay from the Pacific Ocean. 

Please refer to Figure 1–1 of the Navy’s 

rulemaking/LOA application for a map 

of the HSTT Study Area, Figures 2–1 to 

2–4 for the Hawaii Operating Area 

(where the majority of training and 

testing activities occur within the 

Hawaii Range Complex), Figures 2–5 to 

2–7 for the SOCAL Range Complex, and 

Figure 2–8 for the Silver Strand 

Training Complex. The following types 

of training and testing, which are 

classified as military readiness activities 

pursuant to the MMPA, as amended by 

the 2004 NDAA, would be covered 

under the LOAs (if authorized): 

Amphibious warfare (in-water 

detonations), anti-submarine warfare 

(sonar and other transducers, in-water 

detonations), surface warfare (in-water 

detonations), mine warfare (sonar and 

other transducers, in-water detonations), 

and other warfare activities (sonar and 

other transducers, pile driving, air 

guns). 

This will be NMFS’s third rulemaking 

(Hawaii and Southern California were 

separate rules in Phase I) for HSTT 

activities under the MMPA. NMFS 

published the first two rules for Phase 

I effective from January 5, 2009, through 

January 5, 2014, (74 FR 1456; on January 

12, 2009) and effective January 14, 2009, 

through January 14, 2014 (74 FR 3882 

on January 21, 2009) for Hawaii and 

Southern California, respectively. The 

rulemaking for Phase II (combined both 

Hawaii and Southern California) is 

applicable from December 24, 2013, 

through December 24, 2018 (78 FR 

78106; on December 24, 2013). For this 

third rulemaking, the Navy is proposing 

to conduct similar activities as they 

have conducted over the past nine years 

under the previous rulemakings. 

Background of Request 

The Navy’s mission is to organize, 

train, equip, and maintain combat-ready 

naval forces capable of winning wars, 

deterring aggression, and maintaining 

freedom of the seas. This mission is 

mandated by Federal law (10 U.S.C. 

5062), which ensures the readiness of 

the naval forces of the United States. 

The Navy executes this responsibility by 

training and testing at sea, often in 

designated operating areas (OPAREA) 

and testing and training ranges. The 

Navy must be able to access and utilize 

these areas and associated sea space and 

air space in order to develop and 

maintain skills for conducting naval 

activities. 

The Navy proposes to conduct 

training and testing activities within the 

HSTT Study Area. The Navy has been 

conducting similar military readiness 

activities in the Study Area since the 

1940s. The tempo and types of training 

and testing activities have fluctuated 

because of the introduction of new 

technologies, the evolving nature of 

international events, advances in 

warfighting doctrine and procedures, 

and changes in force structure 

(organization of ships, weapons, and 

personnel). Such developments 

influence the frequency, duration, 

intensity, and location of required 

training and testing activities, but the 

basic nature of sonar and explosive 

events conducted in the HSTT Study 

Area has remained the same. 

The Navy’s rulemaking/LOA 

application reflects the most up to date 

compilation of training and testing 

activities deemed necessary to 

accomplish military readiness 

requirements. The types and numbers of 

activities included in the proposed rule 

account for fluctuations in training and 

testing in order to meet evolving or 

emergent military readiness 

requirements. 

Description of the Specified Activity 

The Navy is requesting authorization 

to take marine mammals incidental to 

conducting training and testing 

activities. The Navy has determined that 

acoustic and explosives stressors are 

most likely to result in impacts on 

marine mammals that could rise to the 

level of harassment. Detailed 

descriptions of these activities are 

provided in the HSTT Draft 

Environmental Impact Statement 

(DEIS)/Overseas EIS (OEIS) (DEIS/OEIS) 

and in the Navy’s rule making/LOA 

application (www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

incidental-take-authorizations-militaryreadiness-activities) and are 

summarized here. 

Overview of Training and Testing 

Activities 

The Navy routinely trains and tests in 

the HSTT Study Area in preparation for 

national defense missions. Training and 

testing activities covered in the Navy’s 

rulemaking/LOA application are briefly 

described below, and in more detail 

within Chapter 2 of the HSTT DEIS/ 

OEIS. 

Primary Mission Areas 

The Navy categorizes its activities 

into functional warfare areas called 

primary mission areas. These activities 

generally fall into the following seven 

primary mission areas: Air warfare; 

amphibious warfare; anti-submarine 

warfare (ASW); electronic warfare; 

expeditionary warfare; mine warfare 

(MIW); and surface warfare (SUW). Most 

activities addressed in the HSTT DEIS/ 

OEIS are categorized under one of the 

primary mission areas; the testing 

community has three additional 

categories of activities for vessel 

evaluation, unmanned systems, and 

acoustic and oceanographic science and 

technology. Activities that do not fall 

within one of these areas are listed as 

‘‘other activities.’’ Each warfare 

community (surface, subsurface, 

aviation, and special warfare) may train 

in some or all of these primary mission 

areas. The testing community also 

categorizes most, but not all, of its 

testing activities under these primary 

mission areas. 

The Navy describes and analyzes the 

impacts of its training and testing 

activities within the HSTT DEIS/OEIS 

and the Navy’s rulemaking/LOA 

application. In its assessment, the Navy 

concluded that sonar and other 

transducers, in-water detonations, air 

guns, and pile driving/removal were the 

stressors that would result in impacts on 

marine mammals that could rise to the 

level of harassment (and serious injury 

or mortality by explosives or by vessel 

strike) as defined under the MMPA. The 

Navy’s rulemaking/LOA application 

provides the Navy’s assessment of 

potential effects from these stressors in 


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terms of the various warfare mission 

areas in which they would be 

conducted. In terms of Navy’s primary 

warfare areas, this includes: 

• Amphibious warfare (in-water 

detonations); 

• ASW (sonar and other transducers, 

in-water detonations); 

• SUW (in-water detonations); 

• MIW (sonar and other transducers, 

in-water detonations); and 

• Other warfare activities (sonar and 

other transducers, impact pile driving/ 

vibratory removal, air guns). 

The Navy’s training and testing 

activities in air warfare, electronic 

warfare, and expeditionary warfare do 

not involve sonar or other transducers, 

in-water detonations, pile driving/ 

removal, air guns or any other stressors 

that could result in harassment, serious 

injury, or mortality of marine mammals. 

Therefore, activities in the air, 

electronic or expeditionary warfare 

areas are not discussed further in this 

proposed rule, but are analyzed fully in 

the Navy’s HSTT DEIS/OEIS. 

Amphibious Warfare 

The mission of amphibious warfare is 

to project military power from the sea to 

the shore (i.e., attack a threat on land by 

a military force embarked on ships) 

through the use of naval firepower and 

expeditionary landing forces. 

Amphibious warfare operations range 

from small unit reconnaissance or raid 

missions to large scale amphibious 

exercises involving multiple ships and 

aircraft combined into a strike group. 

Amphibious warfare training ranges 

from individual, crew, and small unit 

events to large task force exercises. 

Individual and crew training include 

amphibious vehicles and naval gunfire 

support training. Such training includes 

shore assaults, boat raids, airfield or 

port seizures, and reconnaissance. Large 

scale amphibious exercises involve 

ship-to-shore maneuver, naval fire 

support, such as shore bombardment, 

and air strike and attacks on targets that 

are in close proximity to friendly forces. 

Testing of guns, munitions, aircraft, 

ships, and amphibious vessels and 

vehicles used in amphibious warfare is 

often integrated into training activities 

and, in most cases, the systems are used 

in the same manner in which they are 

used for fleet training activities. 

Amphibious warfare tests, when 

integrated with training activities or 

conducted separately as full operational 

evaluations on existing amphibious 

vessels and vehicles following 

maintenance, repair, or modernization, 

may be conducted independently or in 

conjunction with other amphibious ship 

and aircraft activities. Testing is 

performed to ensure effective ship-toshore coordination and transport of 

personnel, equipment, and supplies. 

Tests may also be conducted 

periodically on other systems, vessels, 

and aircraft intended for amphibious 

operations to assess operability and to 

investigate efficacy of new technologies. 

Anti-Submarine Warfare 

The mission of ASW is to locate, 

neutralize, and defeat hostile submarine 

forces that threaten Navy forces. ASW is 

based on the principle that surveillance 

and attack aircraft, ships, and 

submarines all search for hostile 

submarines. These forces operate 

together or independently to gain early 

warning and detection, and to localize, 

track, target, and attack submarine 

threats. ASW training addresses basic 

skills such as detecting and classifying 

submarines, as well as evaluating 

sounds to distinguish between enemy 

submarines and friendly submarines, 

ships, and marine life. More advanced 

training integrates the full spectrum of 

ASW from detecting and tracking a 

submarine to attacking a target using 

either exercise torpedoes (i.e., torpedoes 

that do not contain a warhead) or 

simulated weapons. These integrated 

ASW training exercises are conducted 

in coordinated, at-sea training events 

involving submarines, ships, and 

aircraft. Testing of ASW systems is 

conducted to develop new technologies 

and assess weapon performance and 

operability with new systems and 

platforms, such as unmanned systems. 

Testing uses ships, submarines, and 

aircraft to demonstrate capabilities of 

torpedoes, missiles, countermeasure 

systems, and underwater surveillance 

and communications systems. Tests 

may be conducted as part of a largescale fleet training event involving 

submarines, ships, fixed-wing aircraft, 

and helicopters. These integrated 

training events offer opportunities to 

conduct research and acquisition 

activities and to train crews in the use 

of new or newly enhanced systems 

during a large-scale, complex exercise. 

Mine Warfare 

The mission of MIW is to detect, 

classify, and avoid or neutralize 

(disable) mines to protect Navy ships 

and submarines and to maintain free 

access to ports and shipping lanes. MIW 

also includes offensive mine laying to 

gain control of or deny the enemy access 

to sea space. Naval mines can be laid by 

ships, submarines, or aircraft. MIW 

neutralization training includes 

exercises in which ships, aircraft, 

submarines, underwater vehicles, 

unmanned vehicles, or marine mammal 

detection systems search for mine 

shapes. Personnel train to destroy or 

disable mines by attaching underwater 

explosives to or near the mine or using 

remotely operated vehicles to destroy 

the mine. Towed influence mine sweep 

systems mimic a particular ship’s 

magnetic and acoustic signature, which 

would trigger a real mine causing it to 

explode. 

Testing and development of MIW 

systems is conducted to improve sonar, 

laser, and magnetic detectors intended 

to hunt, locate, and record the positions 

of mines for avoidance or subsequent 

neutralization. MIW testing and 

development falls into two primary 

categories: Mine detection or 

classification, and mine countermeasure 

and neutralization. Mine detection or 

classification testing involves the use of 

air, surface, and subsurface vessels and 

uses sonar, including towed and 

sidescan sonar, and unmanned vehicles 

to locate and identify objects 

underwater. Mine detection and 

classification systems are sometimes 

used in conjunction with a mine 

neutralization system. Mine 

countermeasure and neutralization 

testing includes the use of air, surface, 

and subsurface units to evaluate the 

effectiveness of detection systems, 

countermeasure and neutralization 

systems. Most neutralization tests use 

mine shapes, or non-explosive practice 

mines, to evaluate a new or enhanced 

capability. For example, during a mine 

neutralization test, a previously located 

mine is destroyed or rendered 

nonfunctional using a helicopter or 

manned/unmanned surface vehicle 

based system that may involve the 

deployment of a towed neutralization 

system. 

A small percentage of MIW tests 

require the use of high-explosive mines 

to evaluate and confirm the ability of 

the system or the crews conducting the 

training or testing to neutralize a highexplosive mine under operational 

conditions. The majority of MIW 

systems are deployed by ships, 

helicopters, and unmanned vehicles. 

Tests may also be conducted in support 

of scientific research to support these 

new technologies. 

Surface Warfare (SUW) 

The mission of SUW is to obtain 

control of sea space from which naval 

forces may operate, and conduct 

offensive action against other surface, 

subsurface, and air targets while also 

defending against enemy forces. In 

conducting SUW, aircraft use guns, airlaunched cruise missiles, or other 

precision-guided munitions; ships 

employ torpedoes, naval guns, and 


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surface-to-surface missiles; and 

submarines attack surface ships using 

torpedoes or submarine-launched, antiship cruise missiles. SUW includes 

surface-to-surface gunnery and missile 

exercises; air-to-surface gunnery, 

bombing, and missile exercises; 

submarine missile or torpedo launch 

events, and the use of other munitions 

against surface targets. 

Testing of weapons used in SUW is 

conducted to develop new technologies 

and to assess weapon performance and 

operability with new systems and 

platforms, such as unmanned systems. 

Tests include various air-to-surface guns 

and missiles, surface-to-surface guns 

and missiles, and bombing tests. Testing 

events may be integrated into training 

activities to test aircraft or aircraft 

systems in the delivery of munitions on 

a surface target. In most cases the tested 

systems are used in the same manner in 

which they are used for fleet training 

activities. 

Other Warfare Activities 

Naval forces conduct additional 

training, testing and maintenance 

activities, which fall under other 

primary mission areas that are not listed 

above. The HSTT DEIS/OEIS combines 

these training and testing activities 

together in an ‘‘other activities’’ 

grouping for simplicity. These training 

and testing activities include, but are 

not limited to, sonar maintenance for 

ships and submarines, submarine 

navigation and under-ice certification, 

elevated causeway system (pile driving 

and removal), and acoustic and 

oceanographic research. These activities 

include the use of various sonar 

systems, impact pile driving/vibratory 

extraction, and air guns. 

Overview of Major Training Exercises 

and Other Exercises Within the HSTT 

Study Area 

A major training exercise (MTE) is 

comprised of several ‘‘unit level’’ range 

exercises conducted by several units 

operating together while commanded 

and controlled by a single commander. 

These exercises typically employ an 

exercise scenario developed to train and 

evaluate the strike group in naval 

tactical tasks. In an MTE, most of the 

activities being directed and 

coordinated by the strike group 

commander are identical in nature to 

the activities conducted during 

individual, crew, and smaller unit level 

training events. In an MTE, however, 

these disparate training tasks are 

conducted in concert, rather than in 

isolation. Some integrated or 

coordinated ASW exercises are similar 

in that they are comprised of several 

unit level exercises but are generally on 

a smaller scale than an MTE, are shorter 

in duration, use fewer assets, and use 

fewer hours of hull-mounted sonar per 

exercise. For the purpose of analysis, 

three key factors are used to identify 

and group major, integrated, and 

coordinated exercises including the 

scale of the exercise, duration of the 

exercise, and amount of hull-mounted 

sonar hours modeled/used for the 

exercise. NMFS considered the effects of 

all training exercises, not just these 

major, integrated, and coordinated 

training exercises in this proposed rule. 

Overview of Testing Activities Within 

the HSTT Study Area 

The Navy’s research and acquisition 

community engages in a broad spectrum 

of testing activities in support of the 

fleet. These activities include, but are 

not limited to, basic and applied 

scientific research and technology 

development; testing, evaluation, and 

maintenance of systems (e.g., missiles, 

radar, and sonar) and platforms (e.g., 

surface ships, submarines, and aircraft); 

and acquisition of systems and 

platforms to support Navy missions and 

give a technological edge over 

adversaries. The individual commands 

within the research and acquisition 

community included in the Navy’s 

rulemaking/LOA application are the 

Naval Air Systems Command, the Naval 

Sea Systems Command, the Office of 

Naval Research, and the Space and 

Naval Warfare Systems Command. 

Testing activities occur in response to 

emerging science or fleet operational 

needs. For example, future Navy 

experiments to develop a better 

understanding of ocean currents may be 

designed based on advancements made 

by non-government researchers not yet 

published in the scientific literature. 

Similarly, future but yet unknown Navy 

operations within a specific geographic 

area may require development of 

modified Navy assets to address local 

conditions. However, any evolving 

testing activities that would be covered 

under this rule would be expected to 

fall within the range of platforms, 

activities, sound sources, and other 

equipment described in this rule and to 

have impacts that fall within the range 

(i.e., nature and extent) of those covered 

within the rule. For example, the Navy 

identifies ‘‘bins’’ of sound sources to 

facilitate analyses—i.e., they identify 

frequency and source level bounds to a 

bin and then analyze the worst case 

scenario for that bin to understand the 

impacts of all of the sources that fall 

within a bin. While the Navy might be 

aware that sound source e.g., XYZ1 will 

definitely be used this year, sound 

source e.g., XYZ2 might evolve for 

testing three years from now, but if it 

falls within the bounds of the same 

sound source bin, it has been analyzed 

and any resulting take authorized. 

Some testing activities are similar to 

training activities conducted by the 

fleet. For example, both the fleet and the 

research and acquisition community fire 

torpedoes. While the firing of a torpedo 

might look identical to an observer, the 

difference is in the purpose of the firing. 

The fleet might fire the torpedo to 

practice the procedures for such a firing, 

whereas the research and acquisition 

community might be assessing a new 

torpedo guidance technology or testing 

it to ensure the torpedo meets 

performance specifications and 

operational requirements. 

Naval Air Systems Command Testing 

Activities 

Naval Air Systems Command testing 

activities generally fall in the primary 

mission areas used by the fleets. Naval 

Air Systems Command activities 

include, but are not limited to, the 

testing of new aircraft platforms (e.g., 

the F–35 Joint Strike Fighter aircraft), 

weapons, and systems (e.g., newly 

developed sonobuoys) that will 

ultimately be integrated into fleet 

training activities. In addition to the 

testing of new platforms, weapons, and 

systems, Naval Air Systems Command 

also conducts lot acceptance testing of 

weapons and systems, such as 

sonobuoys. 

Naval Sea Systems Command Testing 

Activities 

Naval Sea Systems Command 

activities are generally aligned with the 

primary mission areas used by the 

fleets. Additional activities include, but 

are not limited to, vessel evaluation, 

unmanned systems, and other testing 

activities. In the Navy’s rulemaking/ 

LOA application, for testing activities 

occurring at Navy shipyards and piers, 

only system testing is included. 

Testing activities are conducted 

throughout the life of a Navy ship, from 

construction through deactivation from 

the fleet, to verification of performance 

and mission capabilities. Activities 

include pierside and at-sea testing of 

ship systems, including sonar, acoustic 

countermeasures, radars, torpedoes, 

weapons, unmanned systems, and radio 

equipment; tests to determine how the 

ship performs at sea (sea trials); 

development and operational test and 

evaluation programs for new 

technologies and systems; and testing 

on all ships and systems that have 

undergone overhaul or maintenance. 


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Office of Naval Research Testing 

Activities 

As the Department of the Navy’s 

science and technology provider, the 

Office of Naval Research provides 

technology solutions for Navy and 

Marine Corps needs. The Office of Naval 

Research’s mission is to plan, foster, and 

encourage scientific research in 

recognition of its paramount importance 

as related to the maintenance of future 

naval power, and the preservation of 

national security. The Office of Naval 

Research manages the Navy’s basic, 

applied, and advanced research to foster 

transition from science and technology 

to higher levels of research, 

development, test, and evaluation. The 

Office of Naval Research is also a parent 

organization for the Naval Research 

Laboratory, which operates as the 

Navy’s corporate research laboratory 

and conducts a broad multidisciplinary 

program of scientific research and 

advanced technological development. 

Testing conducted by the Office of 

Naval Research in the HSTT Study Area 

includes acoustic and oceanographic 

research, large displacement unmanned 

underwater vehicle (an innovative naval 

prototype) research, and emerging mine 

countermeasure technology research. 

Space and Naval Warfare Systems 

Command Testing Activities 

Space and Naval Warfare Systems 

Command is the information warfare 

systems command for the U.S. Navy. 

The mission of the Space and Naval 

Warfare Systems Command is to 

acquire, develop, deliver, and sustain 

decision superiority for the warfighter. 

Space and Naval Warfare Systems 

Command Systems Center Pacific is the 

research and development part of Space 

and Naval Warfare Systems Command 

focused on developing and transitioning 

technologies in the area of command, 

control, communications, computers, 

intelligence, surveillance, and 

reconnaissance. Space and Naval 

Warfare Systems Command Systems 

Center Pacific conducts research, 

development, test, and evaluation 

projects to support emerging 

technologies for intelligence, 

surveillance, and reconnaissance; antiterrorism and force protection; mine 

countermeasures; anti-submarine 

warfare; oceanographic research; remote 

sensing; and communications. These 

activities include, but are not limited to, 

the testing of surface and subsurface 

vehicles; intelligence, surveillance, and 

reconnaissance/information operations 

sensor systems; underwater surveillance 

technologies; and underwater 

communications. 

The proposed training and testing 

activities were evaluated to identify 

specific components that could act as 

stressors (e.g., acoustic and explosive) 

by having direct or indirect impacts on 

the environment. This analysis included 

identification of the spatial variation of 

the identified stressors. 

Description of Acoustic and Explosive 

Stressors 

The Navy uses a variety of sensors, 

platforms, weapons, and other devices, 

including ones used to ensure the safety 

of Sailors and Marines, to meet its 

mission. Training and testing with these 

systems may introduce acoustic (sound) 

energy or shock waves from explosives 

into the environment. The Navy’s 

rulemaking/LOA application describes 

specific components that could act as 

stressors by having direct or indirect 

impacts on the environment. This 

analysis includes identification of the 

spatial variation of the identified 

stressors. The following subsections 

describe the acoustic and explosive 

stressors for biological resources within 

the Study Area. Stressor/resource 

interactions that were determined to 

have de minimus or no impacts (i.e., 

vessel, aircraft, weapons noise, and 

explosions in air) were not carried 

forward for analysis in the Navy’s 

rulemaking/LOA application. NMFS has 

reviewed the Navy’s analysis and 

conclusions and finds them complete 

and supportable. 

Acoustic Stressors 

Acoustic stressors include acoustic 

signals emitted into the water for a 

specific purpose, such as sonar, other 

transducers (devices that convert energy 

from one form to another—in this case, 

to sound waves), and air guns, as well 

as incidental sources of broadband 

sound produced as a byproduct of 

impact pile driving and vibratory 

extraction. Explosives also produce 

broadband sound but are characterized 

separately from other acoustic sources 

due to their unique hazardous 

characteristics. Characteristics of each of 

these sound sources are described in the 

following sections. 

In order to better organize and 

facilitate the analysis of approximately 

300 sources of underwater sound used 

for training and testing by the Navy, 

including sonars, other transducers, air 

guns, and explosives, a series of source 

classifications, or source bins, was 

developed. The source classification 

bins do not include the broadband 

sounds produced incidental to pile 

driving, vessel or aircraft transits, 

weapons firing and bow shocks. 

The use of source classification bins 

provides the following benefits: 

Provides the ability for new sensors or 

munitions to be covered under existing 

authorizations, as long as those sources 

fall within the parameters of a ‘‘bin;’’ 

improves efficiency of source utilization 

data collection and reporting 

requirements anticipated under the 

MMPA authorizations; ensures a 

conservative approach to all impact 

estimates, as all sources within a given 

class are modeled as the most impactful 

source (highest source level, longest 

duty cycle, or largest net explosive 

weight) within that bin; allows analyses 

to be conducted in a more efficient 

manner, without any compromise of 

analytical results; and provides a 

framework to support the reallocation of 

source usage (hours/explosives) 

between different source bins, as long as 

the total numbers of takes remain within 

the overall analyzed and authorized 

limits. This flexibility is required to 

support evolving Navy training and 

testing requirements, which are linked 

to real world events. 

Sonar and Other Transducers 

Active sonar and other transducers 

emit non-impulsive sound waves into 

the water to detect objects, safely 

navigate, and communicate. Passive 

sonars differ from active sound sources 

in that they do not emit acoustic signals; 

rather, they only receive acoustic 

information about the environment, or 

listen. In the Navy’s rulemaking/LOA 

application, the terms sonar and other 

transducers are used to indicate active 

sound sources unless otherwise 

specified. 

The Navy employs a variety of sonars 

and other transducers to obtain and 

transmit information about the undersea 

environment. Some examples are midfrequency hull-mounted sonars used to 

find and track enemy submarines; highfrequency small object detection sonars 

used to detect mines; high frequency 

underwater modems used to transfer 

data over short ranges; and extremely 

high-frequency (>200 kilohertz (kHz)) 

Doppler sonars used for navigation, like 

those used on commercial and private 

vessels. The characteristics of these 

sonars and other transducers, such as 

source level, beam width, directivity, 

and frequency, depend on the purpose 

of the source. Higher frequencies can 

carry more information or provide more 

information about objects off which they 

reflect, but attenuate more rapidly. 

Lower frequencies attenuate less 

rapidly, so may detect objects over a 

longer distance, but with less detail. 

Propagation of sound produced 

underwater is highly dependent on 


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environmental characteristics such as 

bathymetry, bottom type, water depth, 

temperature, and salinity. The sound 

received at a particular location will be 

different than near the source due to the 

interaction of many factors, including 

propagation loss; how the sound is 

reflected, refracted, or scattered; the 

potential for reverberation; and 

interference due to multi-path 

propagation. In addition, absorption 

greatly affects the distance over which 

higher-frequency sounds propagate. 

Because of the complexity of analyzing 

sound propagation in the ocean 

environment, the Navy relies on 

acoustic models in its environmental 

analyses that consider sound source 

characteristics and varying ocean 

conditions across the HSTT Study Area. 

The sound sources and platforms 

typically used in naval activities 

analyzed in the Navy’s rulemaking/LOA 

application are described in Appendix 

A (Navy Activity Descriptions) of the 

HSTT DEIS/OEIS. The effects of these 

factors are explained in Appendix D 

(Acoustic and Explosive Concepts) of 

the HSTT DEIS/OEIS. Sonars and other 

transducers used to obtain and transmit 

information underwater during Navy 

training and testing activities generally 

fall into several categories of use 

described below. 

Anti-Submarine Warfare 

Sonar used during ASW would impart 

the greatest amount of acoustic energy 

of any category of sonar and other 

transducers analyzed in the Navy’s 

rulemaking/LOA application. Types of 

sonars used to detect enemy vessels 

include hull-mounted, towed, line 

array, sonobuoy, helicopter dipping, 

and torpedo sonars. In addition, 

acoustic targets and decoys 

(countermeasures) may be deployed to 

emulate the sound signatures of vessels 

or repeat received signals. 

Most ASW sonars are mid frequency 

(1–10 kHz) because mid-frequency 

sound balances sufficient resolution to 

identify targets with distance over 

which threats can be identified. 

However, some sources may use higher 

or lower frequencies. Duty cycles (the 

percentage of time acoustic energy is 

transmitted) can vary widely, from 

intermittently active to continuously 

active. For the duty cycle for the AN/ 

SQS–53C, nominally they produce a 1– 

2 sec ping every 50–60 sec. Continuous 

active sonars often have substantially 

lower source levels but transmit the 

sonar signal much more frequently 

(greater than 80 percent of the time) 

when they are on. The beam width of 

ASW sonars can be wide-ranging in a 

search mode or highly directional in a 

track mode. 

Most ASW activities involving 

submarines or submarine targets would 

occur in waters greater than 600 feet (ft) 

deep due to safety concerns about 

running aground at shallower depths. 

Sonars used for ASW activities would 

typically be used in waters greater than 

200 meters (m) which can vary from 

beyond three nautical miles (nmi) to 12 

nmi or more from shore depending on 

local bathymetry. Exceptions include 

use of dipping sonar by helicopters, 

maintenance of vessel systems while in 

port, and system checks while vessels 

transit to or from port. 

Mine Warfare, Small Object Detection, 

and Imaging 

Sonars used to locate mines and other 

small objects, as well those used in 

imaging (e.g., for hull inspections or 

imaging of the seafloor), are typically 

high frequency or very high frequency. 

Higher frequencies allow for greater 

resolution but, due to their greater 

attenuation, are most effective over 

shorter distances. Mine detection sonar 

can be deployed (towed or vessel hullmounted) at variable depths on moving 

platforms (ships, helicopters, or 

unmanned vehicles) to sweep a 

suspected mined area. Most hullmounted anti-submarine sonars can also 

be used in an object detection mode 

known as ‘‘Kingfisher’’ mode. Sonars 

used for imaging are usually used in 

close proximity to the area of interest, 

such as pointing downward near the 

seafloor. 

Mine detection sonar use would be 

concentrated in areas where practice 

mines are deployed, typically in water 

depths less than 200 ft and at 

established minefields or temporary 

minefields close to strategic ports and 

harbors. Kingfisher mode on vessels is 

most likely to be used when transiting 

to and from port. Sound sources used 

for imaging could be used throughout 

the HSTT Study Area. 

Navigation and Safety 

Similar to commercial and private 

vessels, Navy vessels employ 

navigational acoustic devices including 

speed logs, Doppler sonars for ship 

positioning, and fathometers. These may 

be in use at any time for safe vessel 

operation. These sources are typically 

highly directional to obtain specific 

navigational data. 

Communication 

Sound sources used to transmit data 

(such as underwater modems), provide 

location (pingers), or send a single brief 

release signal to bottom-mounted 

devices (acoustic release) may be used 

throughout the HSTT Study Area. These 

sources typically have low duty cycles 

and are usually only used when it is 

desirable to send a detectable acoustic 

message. 

Classification of Sonar and Other 

Transducers 

Sonars and other transducers are 

grouped into classes that share an 

attribute, such as frequency range or 

purpose of use. Classes are further 

sorted by bins based on the frequency or 

bandwidth; source level; and, when 

warranted, the application in which the 

source would be used, as follows: 

• Frequency of the non-impulsive 

acoustic source; 

Æ Low-frequency sources operate 

below 1 kHz; 

Æ Mid-frequency sources operate at 

and above 1 kHz, up to and including 

10 kHz; 

Æ High-frequency sources operate 

above 10 kHz, up to and including 100 

kHz; 

Æ Very high-frequency sources 

operate above 100 kHz but below 200 

kHz; 

• Sound pressure level of the nonimpulsive source; 

Æ Greater than 160 decibels (dB) re 1 

micro Pascal (mPa), but less than 180 dB 

re 1 mPa; 

Æ Equal to 180 dB re 1 mPa and up to 

200 dB re 1 mPa; 

Æ Greater than 200 dB re 1 mPa; 

• Application in which the source 

would be used; 

Æ Sources with similar functions that 

have similar characteristics, such as 

pulse length (duration of each pulse), 

beam pattern, and duty cycle. 

The bins used for classifying active 

sonars and transducers that are 

quantitatively analyzed in the HSTT 

Study Area are shown in Table 1 below. 

While general parameters or source 

characteristics are shown in the table, 

actual source parameters are classified. 


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TABLE 1—SONAR AND TRANSDUCERS QUANTITATIVELY ANALYZED

Source class category Bin Description 

Low-Frequency (LF): Sources that produce signals less than 1 

kHz.

LF3 

LF4 

LF sources greater than 200 dB. 

LF sources equal to 180 dB and up to 200 dB. 

LF5 LF sources less than 180 dB. 

LF6 LF sources greater than 200 dB with long pulse lengths. 

Mid-Frequency (MF): Tactical and non-tactical sources that 

produce signals between 1–10 kHz.

MF1 

MF1K 

Hull-mounted surface ship sonars (e.g., AN/SQS–53C and AN/ 

SQS–60). 

Kingfisher mode associated with MF1 sonars. 

MF3 Hull-mounted submarine sonars (e.g., AN/BQQ–10). 

MF4 Helicopter-deployed dipping sonars (e.g., AN/AQS–22). 

MF5 Active acoustic sonobuoys (e.g., DICASS). 

MF6 Active underwater sound signal devices (e.g., MK84). 

MF8 Active sources (greater than 200 dB) not otherwise binned. 

MF9 Active sources (equal to 180 dB and up to 200 dB) not otherwise binned. 

MF10 Active sources (greater than 160 dB, but less than 180 dB) not 

otherwise binned. 

MF11 Hull-mounted surface ship sonars with an active duty cycle 

greater than 80%. 

MF12 Towed array surface ship sonars with an active duty cycle greater than 80%. 

MF14 Oceanographic MF sonar. 

High-Frequency (HF): Tactical and non-tactical sources that 

produce signals between 10–100 kHz.

HF1 

HF3 

Hull-mounted submarine sonars (e.g., AN/BQQ–10). 

Other hull-mounted submarine sonars (classified). 

HF4 Mine detection, classification, and neutralization sonar (e.g., 

AQS–20). 

HF5 Active sources (greater than 200 dB) not otherwise binned. 

HF6 Active sources (equal to 180 dB and up to 200 dB) not otherwise binned. 

HF7 Active sources (greater than 160 dB, but less than 180 dB) not 

otherwise binned. 

HF8 Hull-mounted surface ship sonars (e.g., AN/SQS–61). 

Very High-Frequency Sonars (VHF): Non-tactical sources that 

produce signals between 100–200 kHz.

VHF1 VHF sources greater than 200 dB. 

Anti-Submarine Warfare (ASW): Tactical sources (e.g., active 

sonobuoys and acoustic counter-measures systems) used during ASW training and testing activities.

ASW1 

ASW2 

ASW3 

MF systems operating above 200 dB. 

MF Multistatic Active Coherent sonobuoy (e.g., AN/SSQ–125). 

MF towed active acoustic countermeasure systems (e.g., AN/ 

SLQ–25). 

ASW4 MF expendable active acoustic device countermeasures (e.g., 

MK 3). 

ASW5 MF sonobuoys with high duty cycles. 

Torpedoes (TORP): Source classes associated with the active 

acoustic signals produced by torpedoes.

TORP1 

TORP2 

TORP3 

Lightweight torpedo (e.g., MK 46, MK 54, or Anti-Torpedo Torpedo). 

Heavyweight torpedo (e.g., MK 48). 

Heavyweight torpedo (e.g., MK 48). 

Forward Looking Sonar (FLS): Forward or upward looking object 

avoidance sonars used for ship navigation and safety.

FLS2 HF sources with short pulse lengths, narrow beam widths, and 

focused beam patterns. 

Acoustic Modems (M): Systems used to transmit data through the 

water.

M3 MF acoustic modems (greater than 190 dB). 

Swimmer Detection Sonars (SD): Systems used to detect divers 

and submerged swimmers.

SD1–SD2 HF and VHF sources with short pulse lengths, used for the detection of swimmers and other objects for the purpose of port 

security. 

Synthetic Aperture Sonars (SAS): Sonars in which active acoustic 

signals are post-processed to form high-resolution images of 

the seafloor.

SAS1 

SAS2 

SAS3 

SAS4 

MF SAS systems. 

HF SAS systems. 

VHF SAS systems. 

MF to HF broadband mine countermeasure sonar. 

Broadband Sound Sources (BB): Sonar systems with large frequency spectra, used for various purposes.BB1 

BB2 

BB4 

BB5 

BB6 

BB7 

MF to HF mine countermeasure sonar. 

HF to VHF mine countermeasure sonar. 

LF to MF oceanographic source. 

LF to MF oceanographic source. 

HF oceanographic source. 

LF oceanographic source. 

Notes: ASW: Antisubmarine Warfare; BB: Broadband Sound Sources; FLS: Forward Looking Sonar; HF: High-Frequency; LF: Low-Frequency; 

M: Acoustic Modems; MF: Mid-Frequency; SAS: Synthetic Aperture Sonars; SD: Swimmer Detection Sonars; TORP: Torpedoes; VHF: Very

High-Frequency. 

Air Guns 

Air guns are essentially stainless steel 

tubes charged with high-pressure air via 

a compressor. An impulsive sound is 

generated when the air is almost 

instantaneously released into the 

surrounding water. Small air guns with 

capacities up to 60 cubic inches (in3) 

would be used during testing activities 

in various offshore areas of the Southern 

California Range Complex and in the 

Hawaii Range Complex. 


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Generated impulses would have short 

durations, typically a few hundred 

milliseconds, with dominant 

frequencies below 1 kHz. The rootmean-square sound pressure level (SPL) 

and peak pressure (SPL peak) at a 

distance 1 m from the air gun would be 

approximately 215 dB re 1 mPa and 227 

dB re 1 mPa, respectively, if operated at 

the full capacity of 60 in3. The size of 

the air gun chamber can be adjusted, 

which would result in lower SPLs and 

sound exposure level (SEL) per shot. 

Pile Driving/Extraction 

Impact pile driving and vibratory pile 

removal would occur during 

construction of an Elevated Causeway 

System (ELCAS), a temporary pier that 

allows the offloading of ships in areas 

without a permanent port. Construction 

of the elevated causeway could occur in 

sandy shallow water coastal areas at 

Silver Strand Training Complex and at 

Camp Pendleton, both in the Southern 

California Range Complex. 

Installing piles for elevated causeways 

would involve the use of an impact 

hammer (impulsive) mechanism with 

both it and the pile held in place by a 

crane. The hammer rests on the pile, 

and the assemblage is then placed in 

position vertically on the beach or, 

when offshore, positioned with the pile 

in the water and resting on the seafloor. 

When the pile driving starts, the 

hammer part of the mechanism is raised 

up and allowed to fall, transferring 

energy to the top of the pile. The pile 

is thereby driven into the sediment by 

a repeated series of these hammer 

blows. Each blow results in an 

impulsive sound emanating from the 

length of the pile into the water column 

as well as from the bottom of the pile 

through the sediment. Because the 

impact wave travels through the steel 

pile at speeds faster than the speed of 

sound in water, a steep-fronted acoustic 

shock wave is formed in the water (note 

this shock wave has very low peak 

pressure compared to a shock wave 

from an explosive) (Reinhall and Dahl, 

2011). An impact pile driver generally 

operates on average 35 blows per 

minute. 

Pile removal involves the use of 

vibratory extraction (non-impulsive), 

during which the vibratory hammer is 

suspended from the crane and attached 

to the top of a pile. The pile is then 

vibrated by hydraulic motors rotating 

eccentric weights in the mechanism, 

causing a rapid up and down vibration 

in the pile. This vibration causes the 

sediment particles in contact with the 

pile to lose frictional grip on the pile. 

The crane slowly lifts up on the 

vibratory driver and pile until the pile 

is free of the sediment. Vibratory 

removal creates continuous nonimpulsive noise at low source levels for 

a short duration. 

The source levels of the noise 

produced by impact pile driving and 

vibratory pile removal from an actual 

ELCAS pile driving and removal are 

shown in Table 2. 

TABLE 2—ELEVATED CAUSEWAY SYSTEM PILE DRIVING AND REMOVAL UNDERWATER SOUND LEVELS

Pile size and type Method Average sound levels at 10 m 

24-in. Steel Pipe Pile ........................................................... Impact 1 ................................. 192 dB re 1 μPa SPL rms. 

182 dB re 1 μPa2s SEL (single strike). 

24-in. Steel Pipe Pile ........................................................... Vibratory 2 ............................. 146 dB re 1 μPa SPL rms. 

145 dB re 1 μPa2s SEL (per second of duration). 

1 Illingworth and Rodkin (2016). 

2 Illingworth and Rodkin (2015). 

Notes: in = inch, SEL = Sound Exposure Level, SPL = Sound Pressure Level, rms = root mean squared, dB re 1 μPa = decibels referenced to 

1 micropascal. 

In addition to underwater noise, the 

installation and removal of piles also 

results in airborne noise in the 

environment. Impact pile driving 

creates in-air impulsive sound about 

100 dBA re 20 mPa at a range of 15 m 

(Illingworth and Rodkin, 2016). During 

vibratory extraction, the three aspects 

that generate airborne noise are the 

crane, the power plant, and the 

vibratory extractor. The average sound 

level recorded in air during vibratory 

extraction was about 85 dBA re 20 mPa 

(94 dB re 20 mPa) within a range of 10– 

15 m (Illingworth and Rodkin, 2015). 

The size of the pier and number of 

piles used in an ELCAS event is 

approximately 1,520 ft long, requiring 

119 supporting piles. Construction of 

the ELCAS would involve intermittent 

impact pile driving over approximately 

20 days. Crews work 24 hours (hrs) a 

day and would drive approximately 6 

piles in that period. Each pile takes 

about 15 minutes to drive with time 

taken between piles to reposition the 

driver. When training events that use 

the ELCAS are complete, the structure 

would be removed using vibratory 

methods over approximately 10 days. 

Crews would remove about 12 piles per 

24-hour period, each taking about 6 

minutes to remove. 

Pile driving for ELCAS training would 

occur in shallower water, and sound 

could be transmitted on direct paths 

through the water, be reflected at the 

water surface or bottom, or travel 

through bottom substrate. Soft 

substrates such as sand bottom at the 

proposed ELCAS locations would 

absorb or attenuate the sound more 

readily than hard substrates (rock), 

which may reflect the acoustic wave. 

Most acoustic energy would be 

concentrated below 1,000 hertz (Hz) 

(Hildebrand, 2009). 

Explosive Stressors 

This section describes the 

characteristics of explosions during 

naval training and testing. The activities 

analyzed in the Navy’s rulemaking/LOA 

application that use explosives are 

described in Appendix A (Navy Activity 

Descriptions) of the HSTT DEIS/OEIS. 

Explanations of the terminology and 

metrics used when describing 

explosives in the Navy’s rulemaking/ 

LOA application are also in Appendix D 

(Acoustic and Explosive Concepts) of 

the HSTT DEIS/OEIS. 

The near-instantaneous rise from 

ambient to an extremely high peak 

pressure is what makes an explosive 

shock wave potentially damaging. 

Farther from an explosive, the peak 

pressures decay and the explosive 

waves propagate as an impulsive, 

broadband sound. Several parameters 

influence the effect of an explosive: The 

weight of the explosive warhead, the 

type of explosive material, the 

boundaries and characteristics of the 

propagation medium, and, in water, the 

detonation depth. The net explosive 

weight, the explosive power of a charge 

expressed as the equivalent weight of 

trinitrotoluene (TNT), accounts for the 

first two parameters. The effects of these 

factors are explained in Appendix D 

(Acoustic and Explosive Concepts) of 

the HSTT DEIS/OEIS. 


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Explosions in Water 

Explosive detonations during training 

and testing activities are associated with 

high-explosive munitions, including, 

but not limited to, bombs, missiles, 

rockets, naval gun shells, torpedoes, 

mines, demolition charges, and 

explosive sonobuoys. Explosive 

detonations during training and testing 

involving the use of high-explosive 

munitions (including bombs, missiles, 

and naval gun shells), could occur in 

the air or at the water’s surface. 

Explosive detonations associated with 

torpedoes and explosive sonobuoys 

could occur in the water column; mines 

and demolition charges could be 

detonated in the water column or on the 

ocean bottom. Most detonations would 

occur in waters greater than 200 ft in 

depth, and greater than 3 nmi from 

shore, although most mine warfare, 

demolition, and some testing 

detonations would occur in shallow 

water close to shore. Those that occur 

close to shore are typically conducted 

on designated ranges. 

In order to better organize and 

facilitate the analysis of explosives used 

by the Navy during training and testing 

that could detonate in water or at the 

water surface, explosive classification 

bins were developed. The use of 

explosive classification bins provides 

the same benefits as described for 

acoustic source classification bins in 

Section 1.4.1 (Acoustic Stressors) of the 

Navy’s rulemaking/LOA application. 

Explosives detonated in water are 

binned by net explosive weight. The 

bins of explosives that are proposed for 

use in the Study Area are shown in 

Table 3 below. 

TABLE 3—EXPLOSIVES ANALYZED

Bin Net explosive weight 1

(lb) Example explosive source 

E1 ....................................................................... 0.1–0.25 ........................................................... Medium-caliber projectile. 

E2 ....................................................................... >0.25–0.5 ......................................................... Medium-caliber projectile. 

E3 ....................................................................... >0.5–2.5 ........................................................... Large-caliber projectile. 

E4 ....................................................................... >2.5–5 .............................................................. Mine neutralization charge. 

E5 ....................................................................... >5–10 ............................................................... 5-inch projectile. 

E6 ....................................................................... >10–20 ............................................................. Hellfire missile. 

E7 ....................................................................... >20–60 ............................................................. Demo block/shaped charge. 

E8 ....................................................................... >60–100 ........................................................... Light-weight torpedo. 

E9 ....................................................................... >100–250 ......................................................... 500 lb. bomb. 

E10 ..................................................................... >250–500 ......................................................... Harpoon missile. 

E11 ..................................................................... >500–650 ......................................................... 650 lb. mine. 

E12 ..................................................................... >650–1,000 ...................................................... 2,000 lb. bomb. 

E13 2 ................................................................... >1,000–1,740 ................................................... Mat weave. 

1 Net Explosive Weight refers to the equivalent amount of TNT. 

2E13 is not modeled for protected species impacts in water because most energy is lost into the air or to the bottom substrate due to detonation in very shallow water. In addition, activities are confined to small cove without regular marine mammal occurrence. These are not single 

charges, but multiple smaller charges detonated simultaneously or within a short time period. 

Propagation of explosive pressure 

waves in water is highly dependent on 

environmental characteristics such as 

bathymetry, bottom type, water depth, 

temperature, and salinity, which affect 

how the pressure waves are reflected, 

refracted, or scattered; the potential for 

reverberation; and interference due to 

multi-path propagation. In addition, 

absorption greatly affects the distance 

over which higher frequency 

components of explosive broadband 

noise can propagate. Appendix D 

(Acoustic and Explosive Concepts) of 

the HSTT DEIS/OEIS explains the 

characteristics of explosive detonations 

and how the above factors affect the 

propagation of explosive energy in the 

water. Because of the complexity of 

analyzing sound propagation in the 

ocean environment, the Navy relies on 

acoustic models in its environmental 

analyses that consider sound source 

characteristics and varying ocean 

conditions across the HSTT Study Area. 

Explosive Fragments 

Marine mammals could be exposed to 

fragments from underwater explosions 

associated with the specified activities. 

When explosive ordnance (e.g., bomb or 

missile) detonates, fragments of the 

weapon are thrown at high-velocity 

from the detonation point, which can 

injure or kill marine mammals if they 

are struck. These fragments may be of 

variable size and are ejected at 

supersonic speed from the detonation. 

The casing fragments will be ejected at 

velocities much greater than debris from 

any target due to the proximity of the 

casing to the explosive material. Risk of 

fragment injury reduces exponentially 

with distance as the fragment density is 

reduced. Fragments underwater tend to 

be larger than fragments produced by inair explosions (Swisdak and Montaro, 

1992). Underwater, the friction of the 

water would quickly slow these 

fragments to a point where they no 

longer pose a threat. Opposingly, the 

blast wave from an explosive detonation 

moves efficiently through the seawater. 

Because the ranges to mortality and 

injury due to exposure to the blast wave 

are likely to far exceed the zone where 

fragments could injure or kill an animal, 

the threshold are assumed to encompass 

risk due to fragmentation. 

Other Stressor—Vessel Strike 

There is a very small chance that a 

vessel utilized in training or testing 

activities could strike a large whale. 

Vessel strikes have the potential to 

result in incidental take from serious 

injury and/or mortality. Vessel strikes 

are not specific to any particular 

training or testing activity, but rather a 

limited, sporadic, and incidental result 

of Navy vessel movement within the 

Study Area. Vessel strikes from 

commercial, recreational, and military 

vessels are known to seriously injure 

and occasionally kill cetaceans 

(Abramson et al., 2011; BermanKowalewski et al., 2010; Calambokidis, 

2012; Douglas et al., 2008; Laggner, 

2009; Lammers et al., 2003; Van der 

Hoop et al., 2012; Van der Hoop et al., 

2013), although reviews of the literature 

on ship strikes mainly involve collisions 

between commercial vessels and whales 

(Jensen and Silber, 2003; Laist et al., 

2001). Vessel speed, size, and mass are 

all important factors in determining 

potential impacts of a vessel strike to 

marine mammals (Conn and Silber, 

2013; Gende et al., 2011; Silber et al., 

2010; Vanderlaan and Taggart, 2007; 


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Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 29881 

Wiley et al., 2016). For large vessels, 

speed and angle of approach can 

influence the severity of a strike. The 

average speed of large Navy ships ranges 

between 10 and 15 knots (kn) and 

submarines generally operate at speeds 

in the range of 8–13 kn, while a few 

specialized vessels can travel at faster 

speeds. By comparison, this is slower 

than most commercial vessels where 

full speed for a container ship is 

typically 24 kn (Bonney and Leach, 

2010). Additional information on Navy 

vessel movements is provided in the 

Specified Activities section. 

The Center for Naval Analysis 

conducted studies to determine traffic 

patterns of Navy and non-Navy vessels 

in the HSTT Study Area (Mintz, 2016; 

Mintz and Filadelfo, 2011; Mintz, 2012; 

Mintz and Parker, 2006). The most 

recent analysis covered the 5-year 

period from 2011 to 2015 for vessels 

over 65 ft in length (Mintz, 2016). 

Categories of vessels included in the 

study were U.S. Navy surface ship 

traffic and non-military civilian traffic 

such as cargo vessels, bulk carriers, 

commercial fishing vessels, oil tankers, 

passenger vessels, tugs, and research 

vessels (Mintz, 2016). In the Hawaii 

Range Complex, civilian commercial 

shipping comprised 89 percent of total 

vessel traffic while Navy ship traffic 

accounted for eight percent (Mintz, 

2016). In the Southern California Range 

Complex civilian commercial shipping 

comprised 96 percent of total vessel 

traffic while Navy ship traffic accounted 

for four percent (Mintz, 2016). 

Navy ships transit at speeds that are 

optimal for fuel conservation or to meet 

training and testing requirements. Small 

craft (for purposes of this analysis, less 

than 18 m in length) have much more 

variable speeds (0–50+ kn, dependent 

on the activity). Submarines generally 

operate at speeds in the range of 8–13 

kn. While these speeds are considered 

averages and representative of most 

events, some vessels need to operate 

outside of these parameters for certain 

times or during certain activities. For 

example, to produce the required 

relative wind speed over the flight deck, 

an aircraft carrier engaged in flight 

operations must adjust its speed through 

the water accordingly. Also, there are 

other instances such as launch and 

recovery of a small rigid hull inflatable 

boat; vessel boarding, search, and 

seizure training events; or retrieval of a 

target when vessels would be dead in 

the water or moving slowly ahead to 

maintain steerage. There are a few 

specific events, including high-speed 

tests of newly constructed vessels, 

where vessels would operate at higher 

speeds. 

Large Navy vessels (greater than 18 m 

in length) within the offshore areas of 

range complexes and testing ranges 

operate differently from commercial 

vessels in ways that may reduce 

potential whale collisions. Surface ships 

operated by or for the Navy have 

multiple personnel assigned to stand 

watch at all times, when a ship or 

surfaced submarine is moving through 

the water (underway). A primary duty of 

personnel standing watch on surface 

ships is to detect and report all objects 

and disturbances sighted in the water 

that may indicate a threat to the vessel 

and its crew, such as debris, a 

periscope, surfaced submarine, or 

surface disturbance. Per vessel safety 

requirements, personnel standing watch 

also report any marine mammals sighted 

in the path of the vessel as a standard 

collision avoidance procedure. All 

vessels proceed at a safe speed so they 

can take proper and effective action to 

avoid a collision with any sighted object 

or disturbance, and can be stopped 

within a distance appropriate to the 

prevailing circumstances and 

conditions. 

Specified Activities 

Proposed Training Activities 

The Navy’s Specified Activities are 

presented and analyzed as a 

representative year of training to 

account for the natural fluctuation of 

training cycles and deployment 

schedules that generally influences the 

actual level of training that occurs year 

after year in any five-year period. Using 

a representative level of activity rather 

than a maximum tempo of training 

activity in every year is more reflective 

of the amount of hull-mounted midfrequency active sonar estimated to be 

necessary to meet training requirements. 

It also means that the Navy is requesting 

fewer hours of hull-mounted midfrequency active sonar. Both unit-level 

training and major training exercises 

have been adjusted to meet this 

representative year, as discussed below. 

For the purposes of the Navy’s 

rulemaking/LOA application, the Navy 

assumes that some unit-level training 

would be conducted using synthetic 

means (e.g., simulators). Additionally, 

the Specified Activities analysis 

assumes that some unit-level active 

sonar training will be accounted for 

during the conduct of coordinated and 

major training exercises. 

The Optimized Fleet Response Plan 

and various training plans identify the 

number and duration of training cycles 

that could occur over a five-year period. 

The Specified Activities considers 

fluctuations in training cycles and 

deployment schedules that do not 

follow a traditional annual calendar but 

instead are influenced by in-theater 

demands and other external factors. 

Similar to unit-level training, the 

Specified Activities does not analyze a 

maximum number carrier strike group 

Composite Training Unit Exercises (one 

type of major exercise) every year, but 

instead assumes a maximum number of 

exercises would occur during two years 

of any five-year period and that a lower 

number of exercises would occur in the 

other 3 years (described in Estimate 

Take section). 

The training activities that the Navy 

proposes to conduct in the HSTT Study 

Area are summarized in Table 4. The 

table is organized according to primary 

mission areas and includes the activity 

name, associated stressors applicable to 

the Navy’s rulemaking/LOA application, 

description of the activity, sound source 

bin, the locations of those activities in 

the HSTT Study Area, and the number 

of Specified Activities. For further 

information regarding the primary 

platform used (e.g., ship or aircraft type) 

see Appendix A (Navy Activity 

Descriptions) of the HSTT DEIS/OEIS. 

BILLING CODE 3510–22–P 


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Table 4. Proposed Training Activities Analyzed within the HSTT Study Area. 

1}/ajvr T:rJd~ing E±erei$es::...£argelntegrntedAnti-Sub~(lrinrt Warfare 

ASW1, 

ASW2, 

Aircraft carrier and ASW3, 

carrier air wing integrates ASW4, 

with surface and ASW5, 

Composite Training submarine units in a HF1, 

Acoustic 

Unit Exercise1 challenging multi-threat LF6, SO CAL 2-3 12 21 days 

operational environment MF1, 

that certifies them ready MF3, 

to deploy. MF4, 

MF5, 

MF11, 

MF12 

A biennial multinational 

training exercise in which 

navies from Pacific Rim HRC 0-1 2 

nations and others 

assemble in Pearl Harbor, 

Hawaii, to conduct 

training throughout the 

Hawaiian Islands in a ASW2, number of warfare areas. 

Marine mammal systems ASW3, 

ASW4, 

may be used during a HF1, Rim of the Pacific 

Rim of the Pacific exercise. Components of HF3, 

Acoustic Exercise1 a Rim of the Pacific HF4,M3, 30 days 

exercise, such as certain MF1, 

mine warfare and MF3, 

MF4, SO CAL 0-1 2 

amphibious training, may MF5, be conducted in the 

Southern California 

MFll 

Range Complex. 
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M4Jor,; TrainingE~erdses·.-:- Medium 1ntt?:grtfiellAntj,..~ubm£Jii~e•1f4r/lll'f .. . · .. ·.· •· .·• .· > .; ···.·. . ... · . 

Aircraft carrier and ASWl, 

carrier air wing integrates ASW2, HRC 1 3 

with surface and ASW3, 

submarine units in a ASW4, 

Fleet challenging multi-threat HFl, 

Acoustic Exercise/Sustainment operational environment LF6, Up to 10 

Exercise1 to maintain ability to MFl, days 

deploy. MF3, SO CAL 5 22 

MF4, 

MF5, 

MFll, 

MF12 

Elements of the anti- ASW3, 

submarine warfare ASW4, 

tracking exercise HFl, 

combine in this exercise LF6, 

Acoustic 

Undersea Warfare of multiple air, surface, MFl, HRC 3 12 4 days Exercise and subsurface units, over MF3, 

a period of several days. MF4, 

Sonobuoys are released MF5, 

from aircraft. Active and MFll, 

passive sonar used. MF12 

.[niepflted!Coordltt(lteaTraining ~·~maU 1ntegrated'A~Su!JinflrUtf!. ~arfare. Tr{ifning J ... .··.· ..... : . .·.··. 

Multiple ships, aircraft, ASW3, HRC 1 2 

Navy Undersea and submarines integrate ASW4, W arfarc Training and the usc of their sensors to 

HFl, 

Acoustic 

Assessment Course search for, detect, MFl, 2-5 days Surface Warfare classify, localize, and 

Advanced Tactical track a threat submarine MF3, SO CAL 2-3 12 

Training in order to launch an MF4, 

exercise torpedo. 

MF5 

~n,tt:gril!ed(Cvor:~m:tlled Tra,i~fng'7C Medlu~ Coqrdmflted An,ti-SubtnftPineWarj'cwt.; T~ainEntr y> ·.··· 

. . •. . .. ... . .. ··. .· . ... . ·. . : .. ·• . .' .•.. . :· . ·.· . ·· ... ··• ...... 

ASW3, HRC 2 10 

ASW4, 

Train prospective HFl, 

Submarine 

submarine Commanding MFl, 

Acoustic 

Commanders Course Officers to operate MF3, 2-3 days 

against surface, air, and MF4, SO CAL 2 2 

subsurface threats. MF5, 

TORPl, 

TORP2 
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JntegrotedJC(}iJr(/i~tateil 'rrainifrg; ... $11Utll (;~ordi~"atifd A~tf-Submarine Warfare '}'rain~g ' · · · ,; .· 

.· ·.·.•·. 

Amphibious Ready 

Group/Marine ASW2, HRC 2 10 

Expeditionary Unit ASW3, 

Exercise Small-scale, short ASW4, 

Group Sail duration, coordinated HFl, 2-3 day 

Acoustic Independent anti-submarine MFl, 

Deployer warfare exercises MF3, s 

Certification MF4, SO CAL 10-14 58 

Exercise/Tailored MF5, 

Anti -Submarine MFll 

Warfare Training 

A11fl?hibi(Jfl,~ Warjari! ·.···· .·.· . . . ·· .. ··· . .··. 

.····· .. · ......... .•.·· .. 

.··· .··.· ; · .. . .. · .. . ·· ·· . 

Surface ship uses 

large-caliber gun to 

support forces ashore; LargeNaval Surface Fire however, land target caliber 

Explosive Support Exercise - simulated at sea. HE 

HRC 

15 75 8 hours Rounds impact water (Wl88) at Sea rounds 

and are scored by (E5) passive acoustic 

hydrophones located 

at or near target area. 

Navy and Marine ASWl, 

LF6, Amphibious Corps forces conduct MFl, 

Acoustic Marine advanced integration MF3, SO CAL 2-3 12 5-7 days Expeditionary Unit training in preparation 

Exercise for deployment MFll, 

certification. MF12, 

HFl 

Amphibious Navy and Marine 

Marine Corps forces conduct 

Acoustic Expeditionary Unit integration training at 

None SO CAL 2-3 12 Up to 21 

sea in preparation for days Integration deployment Exercise certification. 
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Amphibious Ready 

Group exercises arc 

conducted to validate 

the Marine ASW2, 

Expeditionary Unit's ASW3, 

Marine readiness for ASW4, 

Expeditionary Unit deployment and HFl, Up to 21 Acoustic Composite includes small boat MFl, SO CAL 2-3 12 

Training Unit raids; visit, board, MF3, days 

Exercise search, and seizure MF4, 

training; helicopter MF5, 

and mechanized MFll 

amphibious raids; and 

a non-combatant 

evacuation operation. 

A 'S b ; Wi :p··· • > . ·.• .. . . . . ••• .··· · ...... ·.· .. · n_tr.-. .Jt 11t«nne > {l" arf!_ .·.·. ... ·.·.·. ·.· . .. • · •. < .· ... · .. · · ..·. · . ·. . .. . 

Helicopter crews HRC 6 30 

Anti -Submarine 

search for, track, and 

Warfare Torpedo detect submarines. MF4, 

Acoustic 

Exercise- Recoverable air MF5, 2-5 hours 

Helicopter launched torpedoes are TORPl SO CAL 104 520 

employed against 

submarine targets. 

Maritime patrol HRC 10 50 

Anti -Submarine aircraft crews search 

Warfare Torpedo for, track, and detect 

submarines. MF5, Acoustic Exercise- Recoverable air TORPl 2-8 hours 

Maritime Patrol launched torpedoes are SO CAL 25 125 

Aircraft 

employed against 

submarine targets. 

Surface ship crews HRC 50 250 

Anti -Submarine search for, track, and ASW3, 

Acoustic Warfare Torpedo detect submarines. MFl, 2-5 hours 

Exercise - Ship Exercise torpedoes are TORPl SO CAL 117 585 

used during this event. 

Anti -Submarine Submarine crews 

ASW4, 

HRC 48 240 

Warfare Torpedo search for, track, and 

Acoustic Exercise- detect submarines. HFl, 8 hours 

Submarine Exercise torpedoes are 

MF3, SO CAL 13 65 

used during this event. 

TORP2 

Anti -Submarine Helicopter crews HRC 159 795 

Acoustic Warfare Tracking search for, track, and MF4, 2-4 hours 

Exercise- detect submarines. MF5 SOCAL, 524 2,620 PMSR 
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Helicopter HSTT 

Transit 6 30 

Corridor 

Anti -Submarine Maritime patrol HRC 32 160 

Warfare Tracking aircraft aircrews 

Exercise- search for, track, and 

Acoustic Maritime Patrol detect submarines. 

MF5 2-8 hours Aircraft Recoverable air SOCAL, 56 280 

launched torpedoes are PMSR 

employed against 

submarine targets. 

Anti -Submarine Surface ship crews ASW3, HRC 224 1,120 

Acoustic Warfare Tracking search for, track, and MFl, 2-4 hours 

Exercise - Ship detect submarines. MFll, SOCAL, 423 2,115 

MF12 PMSR 

HRC 200 1,000 

Anti -Submarine Submarine crews ASW4, SOCAL, 50 250 

Acoustic 

Warfare Tracking search for, track, and HFl, PMSR 

8 hours ExerciseSubmarine detect submarines. HF3,MF3 HSTT 

Transit 7 35 

Corridor 

HFl, HRC 2 10 

Air, surface, or MF3, 

Explosive, Service Weapons 

submarine crews MF6, 

employ explosive TORP2, 8 hours 

Acoustic Test torpedoes against Explosive SO CAL 1 5 

virtual targets. torpedoes 

(Ell) 

· M.ir:e Walfare> .·· \ •· ..... ...... . · . . .• . .. .: ...... .· 

·. ·.· . .· i ·. .· ·• .··· .. .. · ....... .. 

Airborne Mine Helicopter aircrews 

Acoustic Countermeasure - detect mines using HF4 SO CAL 10 50 2 hours 

Mine Detection towed or laser mine 

detection systems. 

Civilian Port 

Maritime security 

Pearl 

Defense- Harbor, 1 5 

Homeland Security personnel train to HF4, HI Explosive, Anti- protect civilian ports SAS2 Multiple 

Acoustic 

Terrorism/Force against enemy efforts 

E2,E4 San days 

Protection 

to interfere with access Diego, 1-3 12 

Exercises to those ports. CA 
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The Navy deploys HRC 10 50 trained bottlenose 

dolphins (Tursiops 

truncatus) and 

Marine Mammal California sea lions 

Explosive Systems (Zalophus E7 Varies 

californianus) as part SO CAL 175 875 

of the marine mammal 

mine-hunting and 

object -recovery 

system. 

Mine Ship crews detect and HRC 30 150 

Countermeasure avoid mines while HF4, Up to 15 

Acoustic navigating restricted HF8, Exercise - Ship 

areas or channels MF1K SO CAL 92 460 hours 

Sonar 

using active sonar. 

Mine countermeasure 

ship crews detect, 

Mine locate, identify, and 

Acoustic Countermeasure avoid mines while HF4 SO CAL 266 1,330 Up to 15 

Exercise - Surface navigating restricted hours 

areas or channels, such 

as while entering or 

leaving port. 

Mine Ship, small boat, and HRC 6 30 

Countermeasures helicopter crews locate 

Explosive, Mine and disable mines 

HF4, E4 

1.5 to 4 

Acoustic Neutralization using remotely hours 

Remotely Operated operated underwater SO CAL 372 1,860 

Vehicle vehicles. 

HRC 20 100 

(Puuloa) 

Mine 

Personnel disable SO CAL 

Explosive Neutralization 

threat mines using E4,E5, (IB, TAR Up to 4 

Explosive explosive charges. E6,E7 2, TAR 3, hours 

Ordnance Disposal TAR21, 194 970 

SWAT3, 

SOAR) 

Submarine crews HRC 40 200 

Acoustic Submarine Mine practice detecting HF1 6 hours 

Exercise mines in a designated SO CAL 12 60 

area. 
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Ship crews detect and HRC 42 210 

Surface Ship avoid mines while MFlK, Up to 15 Acoustic navigating restricted Object Detection 

areas or channels HF8 SO CAL 164 820 hours 

using active sonar. 

Underwater Military personnel use 

Demolitions explosive charges to 

SO CAL 

Explosive Multiple Charge - destroy barriers or 

E10, El3 (TAR2, 18 90 4 hours 

obstacles to Mat Weave and amphibious vehicle TAR3) 

Obstacle Loading 

access to beach areas. 

Navy divers conduct HRC 25 125 Underwater various levels of (Puuloa) 

Explosive Demolition training and E6,E7 Varies Qualification and certification in placing SO CAL 

Certification underwater demolition (TAR 2) 120 600 

charges. 

" ' • • . . < ·, .. · ..... · .. ·' .· .. . . . Surface Warfar.e . .. ·. < i • •. . ••• . · . .·· · .. 

HRC 187 935 

Bombing Exercise Fixed-wing aircrews SO CAL 640 3,200 

Explosive deliver bombs against El22 1 hour Air-to-Surface surface targets. HSTT 

Transit 5 25 

Corridor 

Gunnery Exercise 

Small boat crews fire HRC 10 50 

Explosive Surface-to-Surface medium-caliber guns El,E2 1 hour 

Boat Mediumat surface targets. SO CAL 14 70 

Caliber 

HRC 32 160 

Gunnery Exercise Surface ship crews fire SO CAL 200 1,000 

Explosive Surface-to-Surface large-caliber guns at E5 Up to 3 

Ship Large-caliber surface targets. HSTT hours 

Transit 13 65 

Corridor 

HRC 50 250 

Gunnery Exercise 

Surface ship crews fire SO CAL 180 900 Surface-to-Surface Explosive Ship Medium- medium-caliber guns El,E2 2-3 hours 

at surface targets. HSTT 

Caliber Transit 40 200 

Corridor 
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Multiple ships, aircraft 

and submarines 

conduct integrated 

Independent multi-warfare training 

Deployer with a surface warfare 

Explosive, Certification emphasis. Serves as a El, E3, SO CAL 1 5 15 days Acoustic Exercise/Tailored ready -to-deploy E6, E10 

Surface Warfare certification for 

Training individual surface 

ships tasked with 

surface warfare 

missions. 

Naval Forces defend HRC 

1 5 against a swarm of (Wl88A) 

surface threats (ships 

Explosive Integrated Live or small boats) with El, E3, 6-8 hours Fire Exercise bombs, missiles, E6, E10 SO CAL 

rockets, and small-, (SOAR) 

1 5 

medium- and largecaliber guns. 

Fixed-wing and HRC 10 50 

helicopter aircrews 

Explosive 

Missile Exercise 

fire air-to-surface E6,E8, 1 hour Air-to-Surface missiles at surface E10 SO CAL 210 1,050 

targets. 

Helicopter aircrews HRC 227 1,135 

Missile Exercise fire both precisionExplosive Air-to-Surface guided and unguided E3 1 hour 

Rocket rockets at surface SO CAL 246 1,230 

targets. 

Surface ship crews HRC 20 100 

Missile Exercise defend against surface (Wl88) 

Explosive Surface-to-Surface threats (ships or small E6, E10 2-5 hours 

boats) and engage SO CAL 

10 50 

them with missiles. (W291) 

Explosive, Sinking Exercise Aircraft, ship, and TORP2, HRC 1-3 7 4-8 hours, 

Acoustic submarine crews E5, E10, over 1-2 
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deliberately sink a El2 days 

seaborne target, 

usually a 

decommissioned ship 

made environmentally 

safe for sinking SO CAL 0-1 1 

according to U.S. 

Environmental 

Protection Agency 

standards, with a 

variety of munitions. 

A pier is constructed 

off of the beach. Piles 

are driven into the Impact 

Elevated Causeway bottom with an impact hanuuer Up to 30 Pile driving System hammer. Piles are or SO CAL 2 10 days removed from seabed vibratory 

via vibratory extractor. extractor 

Only in-water impacts 

are analyzed. 

Functional check of HRC 60 300 

the dipping sonar prior 

Acoustic Kilo Dip to conducting a full MF4 1.5 hours 

test or training event SO CAL 2,400 12,000 

on the dipping sonar. 

Submarine crews Pearl 

operate sonar for Harbor, 220 1,100 

Submarine navigation and object HI 

Acoustic Navigation detection while HFl, MF3 Up to 2 

Exercise transiting into and out San hours 

of port during reduced Diego 80 400 

visibility. Bay, CA 

HRC 260 1,300 

Pearl 

Harbor, 260 1,300 

HI 

Submarine Sonar Maintenance of SO CAL 93 465 submarine sonar Acoustic Maintenance and MF3 Up to 1 

Systems Checks systems is conducted San hour 

pierside or at sea. Diego 92 460 

Bay, CA 

HSTT 

Transit 10 50 

Corridor 
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Submarine crews train HRC 12 60 

to operate under ice. 

Acoustic 

Submarine Under Ice conditions are 

HFl 

Ice Certification simulated during SO CAL 6 30 

training and 

certification events. 

HRC 75 375 

Pearl 

Harbor, 80 400 

HI 

Surface Ship Sonar Maintenance of SO CAL 250 1,250 

Acoustic Maintenance and 

surface ship sonar 

HF8,MF1 

Systems Checks systems is conducted San 

pierside or at sea. Diego, 250 1,250 

CA 

HSTT 

Transit 8 40 

Corridor 

Unmanned underwater 

vehicle certification HRC 25 125 

involves training with 

unmanned platforms 

to ensure submarine 

Unmanned crew proficiency. 

Underwater Tactical development FLS2, Acoustic Vehicle Training - involves training with 

M3, SAS2 Certification and various payloads for 

Development multiple purposes to SO CAL 10 50 

ensure that the systems 

can be employed 

effectively in an 

operational 

environment. 

.. .. .. Notes: HRC ~ Hawau Range Complex, SOCAL ~Southern Cahfornm Range Complex, HSTT ~ Hawau-Southern Cahfornm Trammg and 

Testing, PMRF ~ Pacific Missile Range Facility, BARSTUR ~ Barking Sands Tactical Underwater Range, BSURE ~ Barking Sands 

Underwater Range Expansion, PMSR ~Point Mugu Sea Range Overlap, TAR~ Training Area and Range, SOAR~ Southern California 

Anti-Submarine Warfare Range, IB ~Imperial Beach Minefield 

I. Any non-antisubmarine warfare activity that could occur is captured in the individual activities. 

2. For the Bombing Exercise Air-to-Surface, all activities were analyzed with exact bins NEW. 

5 days 

Up to 4 

hours 

2 days 
29892 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

Proposed Testing Activities 

Testing activities covered in the 

Navy’s rulemaking/LOA application are 

described in Table 5 through Table 8. 

The five-year Specified Activities 

presented here is based on the level of 

testing activities anticipated to be 

conducted into the reasonably 

foreseeable future, with adjustments 

that account for changes in the types 

and tempo (increases or decreases) of 

testing activities to meet current and 

future military readiness requirements. 

The Specified Activities includes the 

testing of new platforms, systems, and 

related equipment that will be 

introduced after December 2018 and 

during the period of the rule. The 

majority of testing activities that would 

be conducted under the Specified 

Activities are the same or similar as 

those conducted currently or in the past. 

The Specified Activities includes the 

testing of some new systems using new 

technologies and takes into account 

inherent uncertainties in this type of 

testing. 

Under the Specified Activities, the 

Navy proposes a range of annual levels 

of testing that reflects the fluctuations in 

testing programs by recognizing that the 

maximum level of testing will not be 

conducted each year, but further 

indicates a five-year maximum for each 

activity that will not be exceeded. The 

Specified Activities contains a more 

realistic annual representation of 

activities, but includes years of a higher 

maximum amount of testing to account 

for these fluctuations. 

The tables include the activity name, 

associated stressor(s), description of the 

activity, sound source bin, the areas 

where the activity is conducted, and the 

number of activities per year and per 

five years. Not all sound sources are 

used with each activity. Under the 

‘‘Annual # of Activities’’ column, 

activities show either a single number or 

a range of numbers to indicate the 

number of times that activity could 

occur during any single year. The ‘‘5- 

Year # of Activities’’ is the maximum 

times an activity would occur over the 

5-year period of this request. More 

detailed activity descriptions can be 

found in the HSTT DEIS/OEIS. 

Naval Air Systems Command 

Table 5 summarizes the proposed 

testing activities for the Naval Air 

Systems Command analyzed within the 

HSTT Study Area. 


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Table 5. Proposed Naval Air Systems Command Testing Activities Analyzed within the 

HSTT Study Area. 

Tins event is sinrilar to the training 

event torpedo exercise. Test eva I nates HRC 17-22 

Anti-Submarine anti-submarine warfare systems 

Acoustic Warfare Torpedo onboard rotary-wing and fixed-wing MF5, TORPl 

Test aircraft and the ability to search for, 

detect, classify, localize, track, and SOCAL 35-71 

attack a submarine or similar target. 

This event is similar to the training MF4, MF5, E3 

event anti-submarine tracking 

Anti-Submarine exercise -helicopter. The test 

Explosive, Warfare Tracking evaluates the sensors and systems SOCAL 30-132 Acoustic used to detect and track submarines Test- Helicopter and to ensure that helicopter systems 

used to deploy the tracking systems 

perform to specifications. 

The test evaluates the sensors and 

systems used by maritime patrol HRC 54-61 

Anti-Submarine aircraft to detect and track submarines ASW2, ASW5, Explosive, Warfare Tracking 

Acoustic Test- Maritime and to ensure tl1at aircraft systems MF5, MF6, El, 

used to deploy the tracking systems E3 Patrol Aircraft perform to specifications and meet SOCAL 58-68 

operational requirements. 

Sonobuoys are deployed from surface 

vessels and aircraft to verify the ASW2, ASW5, 

Explosive, Sonobuoy Lot integrity and performance of a lot or HF5, HF6, LF4, SOCAL 160 Acoustic Acceptance Test group of sonobuoys in advance of MF5, MF6, El, 

delivery to the fleet for operational E3,E4 

use. 

A nrine-hunting dipping sonar system 

Airborne Dipping that is deployed from a helicopter and 

Acoustic Sonar Minehunting uses high-frequency sonar for the HF4 SOCAL 0-12 

Test detection and classification of bottom 

and moored nrines. 

95 

2-6 hrs 

247 

252 2 hrs 

284 

4-6 hrs 

310 

800 6 hrs 

12 2 hrs 
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Ex'J)losive 

Acoustic 

Explosive 

Airborne Mine 

Neutralization 

System Test 

Airbome Sonobuoy 

Minehunting Test 

A lest of the airbome urine 

neutralization system that evaluates 

the system's ability to detect and 

destroy urines from an airbome urine 

countermeasures capable helicopter 

(e.g., MH-60). The airbome urine 

neutralization system uses up to four 

umnmmed underwater velricles 

equipped with high-frequency sonar, 

video cameras, and explosive and 

non-explosive neutralizers. 

A urine-hunting system made up of 

sonobuoys deployed from a 

helicopter. A field of sonobuoys, 

using high-frequency sonar, is used 

for detection and classification of 

bottom and moored nrines . 

,, .. ·.· ... · 

:'•. · .. ··.·. .• ··. :< •••• ••••• • ••• 

Air-to-Surface 

Bombing Test 

Air-to-Surface 

Gunnery Test 

Air-to-Surface 

Missile Test 

Rocket Test 

Tins event is siurilar to the training 

event bombing exercise air-to-surface. 

Fixed-wing aircraft lest U1e delivery 

of bombs against surface maritime 

targets with the goal of evaluating the 

bomb, U1e bomb carry and delivery 

system, and any associated systems 

that may have been newly developed 

or enhanced. 

Tins event is similar to the trai1nng 

event gunnery exercise air-to-surface. 

Fixed-wing and rotary-wing aircrews 

evaluate new or enhanced aircraft 

guns against surface maritime targets 

to test that the gun, gun annnunition. 

or associated systems meet required 

specifications or to train aircrew in the 

operation of a new or enhanced 

weapons system. 

Tins event is siurilar to the training 

event urissilc exercise air-to-surface. 

Test may involve both fixed-wing and 

rotary-wing aircraft launclnng 

missiles at surface maritime targets to 

evaluate the weapons system or as 

part of another systems integration 

test. 

Rocket tests arc conducted to evaluate 

the integration, accuracy, 

E4 SOCAL 

HF6 SOCAL 

HRC 

E9 

SOCAL 

HRC 

El 

SOCAL 

HRC 

E6. E9, ElO 

SOCAL 

E3 HRC 

11-31 

1-9 

8 

14 

5 

30-60 

18 

48-60 

2 

75 

21 

40 

70 

25 

240 

90 

276 

lO 

2.5 hrs 

2 hrs 

2 hrs 

2-2.5 hrs 

2-4 hrs 

1.5-2.5 

lrrs 
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perfonnance, and safe separation of 

guided and unguided 2.75-inch 

rockets fired from a hovering or SOCAL 18-22 102 

forward flying helicopter or tilt rotor 

aircraft. 

·o~{t~r 1'eStint:Adiw~es• • •••• 

·· ....• ;·· 

. . ······· . · ..... : . ·.•. •• ..... . ... . , . : . 

·" .·.•· ·.· :. . ... . : . . ... ' ...... ; . . _ ........... .. . •. :- ·· . . . ... ... 

Fuuctional check of a helicopter 

deployed dipping sonar system (e.g., 

Acoustic Kilo Dip AN/AQS-22) prior to conducting a l\1F4 SOCAL 0-6 6 1.5 hrs 

testing or training event using the 

dipping sonar system 

Undersea Range Post installation node survey and test 

Acoustic System Test and periodic testing of range Node l\1F9 HRC 11-28 90 8 hrs 

transrnit functionality. 
29896 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

Table 6 summarizes the proposed 

testing activities for the Naval Sea 

Systems Command analyzed within the 

HSTT Study Area. 


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Table 6. Proposed Naval Sea Systems Command Testing Activities Analyzed within the 

HSTT Study Area. 

Ships and their supporting ASWl, HRC 22 

Anti-Submarine platforms (e.g., rotary-wing aircraft ASW2. 

and mnnanncd aerial systems) ASW3. Acoustic Warfare Mission detect, localize, and prosecute ASW5,MF1, Package Testing submarines. MF4,MF5, SO CAL 23 

MF12, TORPl 

At -sea testing to ensure systems are ASW3, HRC 16 

fully functional in an open ocean ASW4, HFI, HRC- enviromnent. LF4, LF5, M3, 

Acoustic At-Sea Sonar MF1,MF1K, SOCAL 

Testing MF2,MF3, 

MF5,MF9, SO CAL 20-21 

MF10,MF11 

Countermeasure testing involves HRC 8 

the testing of systems that will 

HRC- detect localize, and track incoming 4 

weapons, including marine vessel ASW3. SO CAL 

Acoustic Countermeasure targets. Testing includes surface ASW4.HF5, 

Testing ship torpedo defense systems and TORPl, SO CAL ll 

marine vessel stopping payloads. TORP2 

HSTT 

Transit 2 

Corridor 

Pierside testing to ensure systems Pearl 

are fully functional in a controlled HFl. HF3, Harbor, 7 

Pierside Sonar pierside environment prior to at-sea HF8,M3, HI 

Acoustic Testing test activities. MFI,MF:1, San 

MF9 Diego, 7 

CA 

Pierside and at-sea testing of HRC 4 

submarine systems occurs Pearl periodically following major 

Submarine Sonar maintenance periods and for routine HFl, HF3, Harbor, 17 

Acoustic Testing/Maintenance maintenance. M3,MF3 HI 

San 

Diego, 24 

CA 

110 

4-8 hrs per 

day over 1-

115 2 weeks 

78 

5 4 hrs-11 

days 

99 

40 

20 

4 hrs-6 

55 days 

10 

35 Up to 3 

weeks, 

intermittent 

35 sonar use 

20 

Up to 3 85 weeks, 

intermittent 

sonar use 

120 
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Picrsidc and at-sea testing of ship HRC 3 15 

systems occurs periodically Pearl following major maintenance 

periods and for routine Harbor, 3 15 Up to 3 

Surface Ship Sonar maintenance. ASW3,MF1, HI weeks, Acoustic MF1KMF9, Testing/Maintenance MFlO San intermittent 

Diego, 3 15 sonar use 

CA 

SO CAL 3 15 

Air, surface, or submarine crews ASW3,HF1, HRC 8 40 

employ explosive and non- HF5, HF6, HRC 

Explosive, Torpedo (Explosive) explosive torpedoes against MF1,MF:1, SO CAL 3 15 1-2 days, 

Acoustic Testing artificial targets. MF4,MF5, daylight 

MF6, TORP1, hours only 

TORP2, E8, SO CAL 8 40 

Ell 

Air, surface, or submarine crews ASW3. HRC 8 40 

employ non-e:xvlosive torpedoes ASW4,HF1, HRC against submarines or surface HF6,M3, 9 45 

Torpedo (Non- vessels. MF1,MF3, SO CAL Up to 2 Acoustic Explosive) Testing MF4,MF5, weeks 

MF6, TORPL 

SO CAL 8 40 TORP2, 

TORP3 

. Mme. JyiD'fari y ··•••·· .•·· ·.··' . <.· 

. ·. <, ... ···.· .. • ·. 

.. . · .·.· .. ; •.••..• <·. . .. .·. . ·.> .•• . < • ·.· ....... : . ·•·< .·. . . .. 

Mine Air, surface, and subsurface vessels 1-10 days, 

Explosive, Countermeasure and neutralize threat mines and mine- HF4, E4 SO CAL 11 55 intermittent 

Acoustic Neutralization like objects. use of 

Testing systems 

Mine Vessels and associated aircraft HRC 19 80 1-2 weeks, 

Explosive, Countermeasure conduct urine comrterrneasure HF4. SAS2. interrnillent 

Acoustic Mission Package operations. E4 SO CAL 58 290 use of 

Testing systems 

Air, surface, and subsurface vessels HRC 2 10 Up to 24 

Mine Detection and and systems detect and classify and 

HRC days, up to 

Acoustic Classification avoid mines and mine-like objects. HFl, HF8, SO CAL 2 6 12 hrs 

Testing Vessels also assess their potential MFl,MF5 acoustic susceptibility to mines and mineSO CAL 11 55 daily like objects. 

$nrfoceJEt.tr{a~e \ . ·.·••• . < ..• • •.•• .. · .... ... · .. · .. · ..: .. .. ·;· . ~' ; . . . ..·· .·.• .· .. · .··•··· .. · ..•..... 

·•.·· ... ,· . ;' ' . •: : 

Surface crews test large-caliber HRC 7 35 

Gun Testing - gtms to defend against surface 

HRC- Explosive Large-Caliber targets. E3 SO CAL 72 360 1-2 weeks 

SO CAL 7 35 
29898 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 


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Surface crews test mcdimn-calibcr HRC 4 20 

Gun Testing - guns to defend against surface 

HRC- Explosive Medium-Caliber targets. El SO CAL 48 240 l-2 weeks 

SO CAL 4 20 

Missile and rocket testing includes HRC 13 65 

various missiles or rockets fired 

Missile and Rocket from submarines and surface HRC- 24 120 1 day-2 Explosive Testing combatants. Testing of the Eo SO CAL weeks 

launching system and ship defense 

SO CAL 20 100 is performed. 

llnmimneiJ8_vitems · ..•.· .·. > .'' ····.· .. .' . . ... ... .... ·: :: . ......... ·. · .........•..... · ·.······· .. · 

.. . ·..... ' 

···.·· 

. 

Testing involves the production or HRC 3 15 upgrade of unmanned surface 

Umnanned Surface vehicles. This may include tests of Up to 10 Acoustic Vehicle System urine detection capabilities, HF4, SAS2 days Testing evaluations of the basic functions of SO CAL 4 20 individual platfonns, or complex 

events with multiple vehicles. 

Testing involves the production or HRC 3 15 upgrade of unmmmed underwater 

Unmanned vehicles. This may include tests of Up to 35 Acoustic Underwater Vehicle urine detection capabilities. HF4.MF9 days Testing evaluations of the basic functions of 

individual platforms, or complex SO CAL 291 1,455 

events with multiple vehicles. 

Pessi!LEvaluidlnit > • 

. • >. ·:. ; 

· ... • 

; ; < . . ·· ..... 

····· ; 

.. : .. . . ... . ....• . ·.· .... 

Submarine Sea Submarine weapons and sonar HFL M3. HRC 1 5 

Acoustic Trials- Weapons systems are tested at -sea to meet the MF3,MF9, Up to 7 

System Testing integrated combat system MF10. TORP2 SO CAL 1 5 days 

certification requirements. 

Tests the capabilities of shipboard 

sensors to detect, track, and engage 

HRC 9 45 

surface targets. Testing may include HRCships defending against surface SO CAL 63 313 

Surface Warfare targets using explosive and nonExplosive Testing explosive rounds, gun system El. E5, E8 7 days 

structural test firing, and 

demonstration of the response to SO CAL 14-16 72 Call for Fire against land-based 

targets (simulated by sea-based 

locations). 

Ships demonstrate capability of HRC 7 35 

countermeasure systems and ASW4,HF4, HRC undenvater surveillance, weapons HF8, MFI, 12-16 32 

Acoustic Undersea Warfare engagement, and communications MF4, MF5, SO CAL Up to 10 

Testing systems. Tlris tests slrips ability to MF6, TORP1, days 

detect, track, and engage undersea TORP2 SO CAL 11 51 

targets. 
Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 29899 

Office of Naval Research 

Table 7 summarizes the proposed 

testing activities for the Office of Naval 

Research analyzed within the HSTT 

Study Area. 


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29900 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

Space and Naval Warfare Systems 

Command 

Table 8 summarizes the proposed 

testing activities for the Space and 

Naval Warfare Systems Command 

analyzed within the HSTT Study Area. 

Summary of Acoustic and Explosive 

Sources Analyzed for Training and 

Testing 

Table 9 through Table 12 show the 

acoustic source classes and numbers, 

explosive source bins and numbers, air 

gun sources, and pile driving and 

removal activities associated with Navy 

training and testing activities in the 

HSTT Study Area that were analyzed in 

the Navy’s rulemaking/LOA application. 

Table 9 shows the acoustic source 

classes (i.e., LF, MF, and HF) that could 

occur in any year under the Specified 

Activities for training and testing 

activities. Under the Specified 

Activities, acoustic source class use 

would vary annually, consistent with 

the number of annual activities 

summarized above. The five-year total 

for the Specified Activities takes into 

account that annual variability. 


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Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 29901 


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Table 9. Acoustic Source Classes Analyzed and Numbers Used During Training and 

Testing Activities in the HSTT Study Area. 

Low-Frequency LF sources 

(LF): LF3 greater than 200 H 0 0 195 

Sources that dB 

produce signals LF sources equal H 0 0 589-777 

less than 1 kHz LF4 to 180 dB and up 

to 200 dB c 0 0 20 

LF5 LF sources less H 0 0 1,814-

than 180 dB 

LF sources 

LF6 greater than 200 H 121- 167 668 40-80 dB with long 

Mid-Frequency 

(MF): 5,779- Tactical and non- MF1 H 6,702 28,809 1,540 

tactical sources 

that produce 

signals between 1 Kingfisher mode 

and 10kHz MF1K associated with H 100 500 14 

MF1 sonars 

Hull-mounted 

MF23 surface ship H 0 0 54 

sonars (e.g., 

MF3 H 2,080- 10,440 1,311 2,175 

Helicopterdeployed dipping 

MF4 sonars (e.g., H 414-489 2,070 311-475 

AN/AQS-22 and 

ANI S-13 

Active acoustic 5,704- 5,250- MF5 sonobuoys (e.g., c 28,300 

DICAS 6,124 5,863 

Mid-Frequency Active 

(MF): MF6 underwater sound c 9 45 1,141-

Tactical and non- 1,226 

tactical sources 

that produce Active sources 

signals between 1 MF8 (greater than 200 H 0 0 70 and 10kHz dB) not otherwise 

binned 

MF9 Active sources H 0 0 5,139-

to 180 dB 165 

975 

3,131 

100 

9,950 

240 

5,612 

70 

270 

6,553 

1,717 

27,120 

5,835 

350 

25,753 
29902 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 


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and up to 200 dB) 

not otherwise 

binned 

Active sources 

(greater than 160 1,824- MF10 dB, but less than H 0 0 1,992 9,288 

180 dB) not 

otherwise binned 

Hull-mounted 

surface ship 

MF11 sonars with an H 718-890 3,597 56 280 

active duty cycle 

greater than 80% 

Towed array 

surface ship 

MF12 sonars with an H 161-215 884 660 3,300 

active duty cycle 

greater than 80% 

MF13 MF sonar source H 0 0 300 1,500 

High-Frequency Hull-mounted 

(HF): HFl submarine sonars H 1,795- 8,939 772 3,859 Tactical and non- (e.g., AN/BQQ- 1,816 

tactical sources 10) 

that produce HFMarine 

signals between 10 HF2 Mammal H 0 0 120 600 and 100kHz Monitoring 

System 

Other hullHF3 mounted H 287 1,345 110 549 submarine sonars 

(classified) 

High-Frequency Mine detection, 

(HF): classification, and 16,299- Tactical and non- HF4 neutralization H 2,316 10,380 16,323 81,447 

tactical sources sonar (e.g., 

that produce AN/SQS-20) 

signals between 10 Active sources H 0 0 960 4,800 

and 100kHz HF5 (greater than 200 

dB) not otherwise c 0 0 40 200 

binned 

Active sources 

(equal to 180 dB 1,000- HF6 and up to 200 dB) H 0 0 1,009 5,007 

not otherwise 

binned 

Active sources 

(greater than 160 

HF7 dB, but less than H 0 0 1,380 6,900 

180 dB) not 

otherwise binned 

Hull-mounted 

HF8 surface ship H 118 588 1,032 3,072 sonars (e.g., 

AN/SQS-61) 
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Anti-Submarine l'v1F systems 

Warlare (ASW): ASW1 operating above H 194- 261 1,048 470 2,350 

Tactical sources 200 dB 

(e.g., active MF Multistatic 

sonobuoys and ASW2 Active Coherent c 688-790 3,346 4,334- 23,375 acoustic sonobuoy (e.g., 5,191 

countermeasures AN/SSQ-125) 

systems) used MF towed active 

duringASW acoustic 5,005- training and testing ASW3 countermeasure H 25,955 2,741 13,705 

activities systems (e.g., 6,425 

AN/SLQ-25) 

Anti-Submarine l'v1F expendable Warlare (ASW): active acoustic 

Tactical sources ASW4 device c 1,284- 6,407 2,244 10,910 (e.g., active countermeasures 1,332 

sonobuoys and (e.g., MK 3) acoustic 

countermeasures 

systems) used 

ASW5 l'v1F sonobuoys 

during ASW 4 with high duty H 220-300 1,260 522-592 2,740 

training and testing cycles 

activities 

Torpedoes Lightweight 

(TORP): TORP torpedo (e.g., MK 

Source classes 1 46, MK 54, or c 231-237 1,137 923-971 4,560 

associated with the Anti-Torpedo 

active acoustic Torpedo) 

signals produced TORP Heavyweight c 521-587 2,407 404 1,948 by torpedoes 2 

TORP torpedo (e.g., MK 

3 48) c 0 0 45 225 

Forward Looking HF sources with 

Sonar (FLS): short pulse 

Forward or upward FLS2 lengths, narrow H 28 140 448-544 2,432 looking object beam widths, and 

avoidance sonars focused beam 

used for ship patterns 

navigation and VHF sources with 

safety short pulse 

FLS3 lengths, narrow H 0 0 2,640 13,200 beam widths, and 

focused beam 

patterns 

Acoustic Modems l'v1F acoustic (M): Systems used M3 modems (greater H 61 153 518 2,588 to transmit data 

through the water 

than 190 dB) 

Swimmer HF and VHF 

Detection Sonars sources with short 

(SD): pulse lengths, 

Systems used to SD1 used for the H 0 0 10 50 

detect divers and detection of 

submerged swimmers and 

swimmers other objects for 
29904 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

BILLING CODE 3510–22–C 

Table 10 shows the number of air 

guns shots proposed in the HSTT Study 

Area for training and testing activities. 

TABLE 10—TRAINING AND TESTING AIR GUN SOURCES QUANTITATIVELY ANALYZED IN THE HSTT STUDY AREA

Source class category Bin Unit 1

Training Testing 

Annual 5-year total Annual 5-year total 

Air Guns (AG): Small underwater air guns ............... AG C 0 0 844 4,220 

1 C = count. One count (C) of AG is equivalent to 100 air gun firings. 

Table 11 summarizes the impact pile 

driving and vibratory pile removal 

activities that would occur during a 24- 

hour period. Annually, for impact pile 

driving, the Navy will drive 119 piles, 

two times a year for a total of 238 piles. 

Over the 5-year period of the rule, the 

Navy will drive a total of 1190 piles by 

impact pile driving. Annually, for 

vibratory pile extraction, the Navy will 

extract 119 piles, two times a year for 

a total of 238 piles. Over the 5-year 

period of the rule, the Navy will extract 

a total of 1190 piles by vibratory pile 

extraction. 

TABLE 11—SUMMARY OF PILE DRIVING AND REMOVAL ACTIVITIES PER 24-HOUR PERIOD IN THE HSTT STUDY AREA

Method Piles per 

24-hour period 

Time per pile 

(minutes) 

Total 

estimated time 

of noise per 

24-hour period 

(minutes) 

Pile Driving (Impact) .................................................................................................................... 6 15 90 

Pile Removal (Vibratory) .............................................................................................................. 12 6 72 

Table 12 shows the number of inwater explosives that could be used in 

any year under the Specified Activities 

for training and testing activities. Under 

the Specified Activities, bin use would 

vary annually, consistent with the 

number of annual activities summarized 

above. The five-year total for the 

Specified Activities takes into account 

that annual variability. 


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Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 29905 

TABLE 12—EXPLOSIVE SOURCE BINS ANALYZED AND NUMBERS USED DURING TRAINING AND TESTING ACTIVITIES IN THE

HSTT STUDY AREA

Bin Net explosive 

weight (lb) Example explosive source 

Modeled 

underwater 

detonation 

depths (ft) 1

Training Testing 

Annual 5-year 

total Annual 5-year total 

E1 .......... 0.1–0.25 Medium-caliber projectiles 0.3, 60 .............................. 2,940 14,700 8,916–15,216 62,880 

E2 .......... >0.25–0.5 Medium-caliber projectiles 0.3, 50 .............................. 1,746 8,730 0 0 

E3 .......... >0.5–2.5 Large-caliber projectiles ... 0.3, 60 .............................. 2,797 13,985 2,880–3,124 14,844 

E4 .......... >2.5–5 Mine neutralization charge 10, 16, 33, 50, 61, 65, 650 38 190 634–674 3,065 

E5 .......... >5–10 5 in projectiles .................. 0.3, 10, 50 ........................ 4,730–4,830 23,750 1,400 7,000 

E6 .......... >10–20 Hellfire missile .................. 0.3, 10, 50, 60 .................. 592 2,872 26–38 166 

E7 .......... >20–60 Demo block/shaped 

charge.

10, 50, 60 ......................... 13 65 0 0 

E8 .......... >60–100 Lightweight torpedo .......... 0.3, 150 ............................ 33–88 170 57 285 

E9 .......... >100–250 500 lb bomb ..................... 0.3 ..................................... 410–450 2,090 4 20 

E10 ........ >250–500 Harpoon missile ................ 0.3 ..................................... 219–224 1,100 30 150 

E11 ........ >500–650 650 lb mine ....................... 61, 150 ............................. 7–17 45 12 60 

E12 ........ >650–1,000 2,000 lb bomb .................. 0.3 ..................................... 16–21 77 0 0 

E13 ........ >1,000–1,740 Multiple Mat Weave 

charges.

NA2 ................................... 9 45 0 0 

1 Net Explosive Weight refers to the amount of explosives; the actual weight of a munition may be larger due to other components.

2 Not modeled because charge is detonated in surf zone; not a single E13 charge, but multiple smaller charges detonated in quick succession. 

Notes: in = inch(es), lb = pound(s), ft = feet. 

Vessel Movement 

Vessels used as part of the Specified 

Activities include ships, submarines, 

unmanned vessels, and boats ranging in 

size from small, 22 ft (7 m) rigid hull 

inflatable boats to aircraft carriers with 

lengths up to 1,092 ft (333 m). Large 

Navy ships greater than 60 ft (18 m) 

generally operate at speeds in the range 

of 10 to 15 kn for fuel conservation. 

Submarines generally operate at speeds 

in the range of 8 to 13 kn in transits and 

less than those speeds for certain 

tactical maneuvers. Small craft, less 

than 60 ft (18 m) in length, have much 

more variable speeds (dependent on the 

activity). Speeds generally range from 

10 to 14 kn. While these speeds for large 

and small craft are representative of 

most events, some vessels need to 

temporarily operate outside of these 

parameters. 

The number of Navy vessels used in 

the HSTT Study Area varies based on 

military training and testing 

requirements, deployment schedules, 

annual budgets, and other unpredictable 

factors. Most training and testing 

activities involve the use of vessels. 

These activities could be widely 

dispersed throughout the HSTT Study 

Area, but would be typically conducted 

near naval ports, piers, and range areas. 

Navy vessel traffic would especially be 

concentrated near San Diego, California 

and Pearl Harbor, Hawaii. There is no 

seasonal differentiation in Navy vessel 

use. The majority of large vessel traffic 

occurs between the installations and the 

OPAREAS. Support craft would be more 

concentrated in the coastal waters in the 

areas of naval installations, ports and 

ranges. Activities involving vessel 

movements occur intermittently and are 

variable in duration, ranging from a few 

hours up to two weeks. 

Standard Operating Procedures 

For training and testing to be 

effective, personnel must be able to 

safely use their sensors and weapon 

systems as they are intended to be used 

in a real-world situation and to their 

optimum capabilities. While standard 

operating procedures are designed for 

the safety of personnel and equipment 

and to ensure the success of training 

and testing activities, their 

implementation often yields additional 

benefits to environmental, 

socioeconomic, public health and 

safety, and cultural resources. 

Navy standard operating procedures 

have been developed and refined over 

years of experience and are broadcast 

via numerous naval instructions and 

manuals, including, but not limited to: 

• Ship, submarine, and aircraft safety 

manuals; 

• Ship, submarine, and aircraft 

standard operating manuals; 

• Fleet Area Control and Surveillance 

Facility range operating instructions; 

• Fleet exercise publications and 

instructions; 

• Naval Sea Systems Command test 

range safety and standard operating 

instructions; 

• Navy instrumented range operating 

procedures; 

• Naval shipyard sea trial agendas; 

• Research, development, test, and 

evaluation plans; 

• Naval gunfire safety instructions; 

• Navy planned maintenance system 

instructions and requirements; 

• Federal Aviation Administration 

regulations; and 

• International Regulations for 

Preventing Collisions at Sea. 

Because standard operating 

procedures are essential to safety and 

mission success, the Navy considers 

them to be part of the Specified 

Activities, and has included them in the 

environmental analysis. Standard 

operating procedures that are 

recognized as providing a potential 

benefit to marine mammals during 

training and testing activities are noted 

below and discussed in more detail 

within the HSTT DEIS/OEIS. 

• Vessel Safety 

• Weapons Firing Safety 

• Target Deployment Safety 

• Towed In-Water Device Safety 

• Pile Driving Safety 

Standard operating procedures (which 

are implemented regardless of their 

secondary benefits) are different from 

mitigation measures (which are 

designed entirely for the purpose of 

avoiding or reducing potential impacts 

on the environment). Refer to Section 

1.5.5 Standing Operating Procedures of 

the Navy’s rulemaking/LOA application 

for greater detail. 

Duration and Location 

Training and testing activities would 

be conducted in the HSTT Study Area 

throughout the year from 2018 through 

2023 for the five-year period covered by 

the regulations. The HSTT Study Area 

(see Figure 1.1–1 of the Navy’s 

rulemaking/LOA application) is 

comprised of established operating and 


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29906 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

1 Vessel transit corridors are the routes typically 

used by Navy assets to traverse from one area to 

another. The route depicted in Figure 1–1 of the 

Navy’s rulemaking/LOA application is the shortest 

route between Hawaii and Southern California, 

making it the quickest and most fuel efficient. 

Depicted vessel transit corridor is notional and may 

not represent the actual routes used by ships and 

submarines transiting from Southern California to 

Hawaii and back. Actual routes navigated are based 

on a number of factors including, but not limited 

to, weather, training, and operational requirements. 

warning areas across the north-central 

Pacific Ocean, from the mean high tide 

line in Southern California west to 

Hawaii and the International Date Line. 

The Study Area includes the at-sea areas 

of three existing range complexes (the 

Hawaii Range Complex, the SOCAL 

Range Complex, and the Silver Strand 

Training Complex), and overlaps a 

portion of the Point Mugu Sea Range 

(PMSR). Also included in the Study 

Area are Navy pierside locations in 

Hawaii and Southern California, Pearl 

Harbor, San Diego Bay, and the transit 

corridor 1 on the high seas where sonar 

training and testing may occur. A Navy 

range complex consists of geographic 

areas that encompasses a water 

component (above and below the 

surface), airspace, and may encompass a 

land component where training and 

testing of military platforms, tactics, 

munitions, explosives, and electronic 

warfare systems occur. Range complexes 

include OPAREAs and special use 

airspace, which may be further divided 

to provide better control of the area and 

events being conducted for safety 

reasons. Please refer to the regional 

maps provided in the Navy’s 

rulemaking/LOA application (Figures 2– 

1 through 2–8) for additional detail of 

the range complexes and testing ranges. 

The range complexes and testing ranges 

are described in the following sections. 

Hawaii Range Complex 

The Hawaii Range Complex 

encompasses ocean areas located 

around the Hawaiian Islands chain. The 

ocean areas extend from 16 degrees 

north latitude to 43 degrees north 

latitude and from 150 degrees west 

longitude to the International Date Line, 

forming an area approximately 1,700 

nmi by 1,600 nmi. The largest 

component of the Hawaii Range 

Complex is the Temporary OPAREA, 

extending north and west from the 

island of Kauai, and comprising over 

two million square nautical miles (nmi2) 

of air and sea space. The Temporary 

OPAREA is used primarily for missile 

testing by the Pacific Missile Range 

Facility (PMRF), and those missile tests 

are not part of the Navy’s rulemaking/ 

LOA application and are covered under 

other NEPA analysis. Other non-Navy 

entities such as various academic 

institutions and other Department of 

Defense agencies (DoD) such as the U.S. 

Air Force conduct activities in the 

PMRF. The PMRF activities referred to 

in the HSTT EIS/DEIS are very high 

altitude missile defense tests conducted 

by the Missile Defense Agency (MDA) (a 

non-Navy DoD command). For this 

rulemaking/LOA application, the area is 

used for Navy ship transits throughout 

the year. Despite the Temporary 

OPAREA’s size, nearly all of the training 

and testing activities in the Hawaii 

Range Complex (HRC) take place within 

the smaller Hawaii OPAREA, that 

portion of the range complex 

immediately surrounding the island 

chain from Hawaii to Kauai (Figures 2– 

1 through 2–4 of the Navy’s 

application). The Hawaii OPAREA 

consists of 235,000 nmi2 of special use 

airspace and ocean areas. The HRC 

includes over 115,000 nmi2 of combined 

special use airspace and air traffic 

control assigned airspace. As depicted 

in Figure 2–1 of the Navy’s application, 

this airspace is almost entirely over the 

ocean and includes warning areas, air 

traffic controlled assigned airspace, and 

restricted areas. 

The Hawaii Range Complex includes 

the ocean areas as described above, as 

well as specific training areas around 

the islands of Kauai, Oahu, and Maui 

(Figures 2–2, 2–3, and 2–4 respectively 

of the Navy’s application). The Hawaii 

Range Complex also includes the ocean 

portion of the PMRF on Kauai, which is 

both a fleet training range and a fleet 

and DoD testing range. The facility 

includes 1,100 nmi2 of instrumented 

ocean area at depths between 129 ft and 

15,000 ft. The Hawaii Range Complex 

also includes the ocean areas around the 

designated Papahanaumokuakea Marine 

National Monument, referred hereafter 

as the Monument. Establishment of the 

Monument in June 2006 triggered a 

number of prohibitions on activities 

conducted in the Monument area. 

However, all military activities and 

exercises were specifically excluded 

from the listed prohibitions as long as 

the military exercises and activities are 

carried out in a manner that avoids, to 

the extent practicable and consistent 

with operational requirements, adverse 

impacts on monument resources and 

qualities. In 2016, the Monument was 

expanded from its original 139,818 

square miles (mi2) to 582,578 mi2. The 

expansion of the Monument was 

primarily to the west—away from the 

portion of the Hawaii Range Complex 

where most training and testing 

activities are proposed to occur— and 

retained the military exclusion language 

contained in the monument designation. 

Southern California Range Complex 

The SOCAL Range Complex is located 

between Dana Point and San Diego, and 

extends southwest into the Pacific 

Ocean (Figures 2–5, 2–6, and 2–7 of the 

Navy’s application). Although the range 

complex extends more than 600 nmi 

beyond land, most activities occur with 

200 nmi of Southern California. The two 

primary components of the SOCAL 

Range Complex are the ocean OPAREAs 

and the special use airspace. These 

components encompass 120,000 nmi2 of 

sea space and 113,000 nmi2 of special 

use airspace. Most of the special use 

airspace in the SOCAL Range Complex 

is defined by W–291 (Figure 2–5 of the 

Navy’s application). This warning area 

extends vertically from the ocean 

surface to 80,000 ft above mean sea level 

and encompasses 113,000 nmi2 of 

airspace. The SOCAL Range Complex 

includes approximately 120,000 nmi2 of 

sea and undersea space, largely defined 

as that ocean area underlying the 

Southern California special use airspace 

described above. The SOCAL Range 

Complex also extends beyond this 

airspace to include the surface and 

subsurface area from the northeastern 

border of W–291 to the coast of San 

Diego County, and includes San Diego 

Bay. 

Point Mugu Sea Range Overlap 

A small portion (approximately 1,000 

nmi2) of the Point Mugu Sea Range is 

included in the HSTT Study Area 

(Figure 2–5 of the Navy’s application). 

Only that part of the Point Mugu Sea 

Range is used by the Navy for antisubmarine warfare training. This 

training uses sonar, is conducted in the 

course of major training exercises, and 

is analyzed in this request. 

Silver Strand Training Complex 

The Silver Strand Training Complex 

is an integrated set of training areas 

located on and adjacent to the Silver 

Strand, a narrow, sandy isthmus 

separating the San Diego Bay from the 

Pacific Ocean. It is divided into two 

non-contiguous areas: Silver Strand 

Training Complex-North and Silver 

Strand Training Complex-South (Figure 

2–8 of the Navy’s application). The 

Silver Strand Training Complex-North 

includes 10 oceanside boat training 

lanes (numbered as Boat Lanes 1–10), 

ocean anchorage areas (numbered 101– 

178), bayside water training areas 

(Alpha through Hotel), and the Lilly 

Ann drop zone. The boat training lanes 

are each 500 yards (yd) wide stretching 

4,000 yd seaward and forming a 5,000 


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yd long contiguous training area. The 

Silver Strand Training Complex-South 

includes four oceanside boat training 

lanes (numbered as Boat Lanes 11–14) 

and the TA-Kilo training area. 

The anchorages lie offshore of 

Coronado in the Pacific Ocean and 

overlap a portion of Boat Lanes 1–10. 

The anchorages are each 654 yd in 

diameter and are grouped together in an 

area located primarily due west of Silver 

Strand Training Complex-North, east of 

Zuniga Jetty and the restricted areas on 

approach to the San Diego Bay entrance. 

Ocean Operating Areas Outside the 

Bounds of Existing Range Complexes 

(Transit Corridor) 

In addition to the range complexes 

that are part of the Study Area, a transit 

corridor outside the boundaries of the 

range complexes is also included as part 

of the Study Area in the analysis. 

Although not part of any defined range 

complex, this transit corridor is 

important to the Navy in that it provides 

adequate air, sea, and undersea space in 

which vessels and aircraft conduct 

training and some sonar maintenance 

and testing while enroute between 

Southern California and Hawaii. The 

transit corridor, notionally defined by 

the great circle route (e.g., shortest 

distance) from San Diego to the center 

of the Hawaii Range Complex, as 

depicted in Figure 1–1 of the Navy’s 

application, is generally used by ships 

transiting between the SOCAL Range 

Complex and Hawaii Range Complex. 

While in transit, ships and aircraft 

would, at times, conduct basic and 

routine unit level activities such as 

gunnery, bombing, and sonar training, 

testing, and maintenance, as long as the 

activities do not interfere with the 

primary objective of reaching their 

intended destination. 

Pierside Locations, Pearl Harbor, and 

San Diego Bay 

The Study Area includes select 

pierside locations where Navy surface 

ship and submarine sonar maintenance 

testing occur. For purposes of the 

Navy’s application, pierside locations 

include channels and routes to and from 

Navy ports, and facilities associated 

with Navy ports and shipyards. These 

locations in the Study Area are located 

at Navy ports and naval shipyards in 

Pearl Harbor, Hawaii and in San Diego 

Bay, California (Figure 2–9 of the Navy’s 

application). In addition, some training 

and testing activities occur throughout 

San Diego Bay. 

Description of Marine Mammals and 

Their Habitat in the Area of the 

Specified Activities 

Marine mammal species and their 

associated stocks that have the potential 

to occur in the HSTT Study Area are 

presented in Table 13 along with an 

abundance estimate, an associated 

coefficient of variation value, and best/ 

minimum abundance estimates. The 

Navy proposes to take individuals of 39 

marine mammal species by Level A and 

B harassment incidental to training and 

testing activities from the use of sonar 

and other transducers, in-water 

detonations, air guns, and impact pile 

driving/vibratory extraction activities. 

In addition, the Navy is requesting ten 

mortalities of two marine mammal 

stocks from explosives, and three takes 

of large whales by serious injury or 

mortality from vessel strikes over the 

five-year period. One marine mammal 

species, the Hawaiian monk seal, has 

critical habitat designated under the 

Endangered Species Act in the HSTT 

Study Area (described below). 

Information on the status, 

distribution, abundance, population 

trends, and ecology of marine mammals 

in the HSTT Study Area may be found 

in Chapter 4 of the Navy’s rulemaking/ 

LOA application. Additional 

information on the general biology and 

ecology of marine mammals are 

included in the HSTT DEIS/OEIS. In 

addition, NMFS annually publishes 

Stock Assessment Reports (SARs) for all 

marine mammals in U.S. Exclusive 

Economic Zone (EEZ) waters, including 

stocks that occur within the HSTT 

Study Area and are found specifically in 

the U.S. Pacific Marine Mammal SAR 

(Carretta et al., 2017) (see https://

www.fisheries.noaa.gov/resource/ 

document/us-pacific-marine-mammalstock-assessments-2016). 

The species carried forward for 

analysis (and described in Table 13 

below) are those likely to be found in 

the HSTT Study Area based on the most 

recent data available, and do not 

include stocks or species that may have 

once inhabited or transited the area but 

have not been sighted in recent years 

(e.g., species which were extirpated 

because of factors such as nineteenth 

and twentieth century commercial 

exploitation). Extralimital species, 

species that would not be considered 

part of the HSTT seasonal species 

assemblage (e.g., North Pacific right 

whale, any tropical odontocete species 

in SOCAL), were not included in the 

analysis. 

TABLE 13—MARINE MAMMALS OCCURRENCE WITHIN THE HSTT STUDY AREA

Common name Scientific name Stock 

Status 

Occurrence Seasonal ab- sence 

Stock abundance 

(CV)/minimum 

MMPA ESA population 

Blue whale ........... Balaenoptera 

musculus.

Eastern North 

Pacific.

Depleted ............ Endangered ....... Southern California............................. 1,647 (0.07)/1,551 

Central North Pacific.Depleted ............ Endangered ....... Hawaii ................ Summer ............. 81 (1.14)/38 

Bryde’s whale ...... Balaenoptera 

brydei/edeni.

Eastern Tropical 

Pacific.

............................ ............................ Southern California............................. unknown 

Hawaiian ............ Depleted ............ ............................ Hawaii ................ ............................ 798 (0.28)/633 

Fin whale ............. Balaenoptera 

physalus.

California, Oregon, and 

Washington.

Depleted ............ Endangered ....... Southern California............................. 9,029 (0.12)/8,127 

Hawaiian ............ Depleted ............ Endangered ....... Hawaii ................ Summer ............. 58 (1.12)/27 

Gray whale .......... Eschrichtius 

robustus.

Eastern North 

Pacific.

............................ ............................ Southern California............................. 20,990 (0.05)/20,125 

Western North 

Pacific.

Depleted ............ Endangered ....... Southern California............................. 140 (0.04)/135 

Humpback whale Megaptera 

novaeangliae.

California, Oregon, and 

Washington.

Depleted ............ Threatened/Endangered 1.

Southern California............................. 1,918 (0.03)/1,876 

Central North Pacific............................. ............................ Hawaii ................ Summer ............. 10,103 (0.30)/7,890 

Minke whale ......... Balaenoptera 

acutorostrata.

California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 636 (0.72)/369 

Hawaiian ............ ............................ ............................ Hawaii ................ Summer ............. unknown 


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TABLE 13—MARINE MAMMALS OCCURRENCE WITHIN THE HSTT STUDY AREA—Continued 

Common name Scientific name Stock 

Status 

Occurrence Seasonal ab- sence 

Stock abundance 

(CV)/minimum 

MMPA ESA population 

Sei whale ............. Balaenoptera borealis.Eastern North 

Pacific.

Depleted ............ Endangered ....... Southern California............................. 519 (0.4)/374 

Hawaii ................ Depleted ............ Endangered ....... Hawaii ................ Summer ............. 178 (0.90)/93 

Sperm whale ........ Physeter 

macrocephalus.

California, Oregon, and 

Washington.

Depleted ............ Endangered ....... Southern California............................. 2,106 (0.58)/1,332 

Hawaiian ............ Depleted ............ Endangered ....... Hawaii ................ ............................ 3,354 (0.34)/2,539 

Pygmy sperm 

whale.

Kogia breviceps California, Oregon, and 

Washington.

............................ ............................ Southern California.Winter and Fall .. 4,111 (1.12)/1,924 

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ unknown 

Dwarf sperm 

whale.

Kogia sima ......... California, Oregon, and 

Washington.

............................ ............................ Southern California............................. unknown 

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ unknown 

Baird’s beaked 

whale.

Berardius bairdii California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 847 (0.81)/466 

Blainville’s beaked 

whale.

Mesoplodon 

densirostris.

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 2,338 (1.13)/1,088 

Cuvier’s beaked 

whale.

Ziphius 

cavirostris.

California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 6,590 (0.55)/4,481 

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 1,941 na/1,142 

Longman’s 

beaked whale.

Indopacetus 

pacificus.

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 4,571 (0.65)/2,773 

Mesoplodon 

beaked whales.

Mesoplodon spp. California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 694 (0.65)/389 

Common 

Bottlenose dolphin.

Tursiops 

truncatus.

California Coastal.

California, Oregon, and 

Washington 

Offshore.

............................ ............................ Southern California............................. 453 (0.06)/346 

1,924 (0.54)/1,255 

Hawaiian Pelagic ............................ ............................ Hawain ............... ............................ 5,950 (0.59)/3,755 

Kauai and Niihau ............................ ............................ Hawaii ................ ............................ 184 (0.11)/168 

Oahu .................. ............................ ............................ Hawaii ................ ............................ 743 (0.54)/485 

4-Islands ............ ............................ ............................ Hawaii ................ ............................ 191 (0.24)/156 

Hawaii Island ..... ............................ ............................ Hawaii ................ ............................ 128 (0.13)/115 

False killer whale Pseudorca 

crassidens.

Main Hawaiian 

Islands Insular.

Depleted ............ Endangered ....... Hawaii ................ ............................ 151 (0.20)/92 

Hawaii Pelagic ... ............................ ............................ Hawaii ................ ............................ 1,540 (0.66)/928 

Northwestern Hawaiian Islands............................. ............................ Hawaii ................ ............................ 617 (1.11)/290 

Fraser’s dolphin ... Lagenodelphis 

hosei.

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 16,992 (0.66)/10,241 

Killer whale .......... Orcinus orca ...... Eastern North 

Pacific Offshore.

............................ ............................ Southern California............................. 240 (0.49)/162 

Eastern North 

Pacific Transient/West 

Coast Transient 2.

............................ ............................ Southern California............................. 243 unknown/243 

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 101 (1.00)/50 

Long-beaked common dolphin.Delphinus 

capensis.

California ............ ............................ ............................ Southern California............................. 101,305 (0.49)/68,432 

Melon-headed 

whale.

Peponocephala 

electra.

Hawaiian Islands 

Kohala Resident 

............................ ............................ Hawaii ................ ............................ 5,794 (0.20)/4,904 

447 (0.12)/404 

Northern right 

whale dolphin.

Lissodelphis borealis.California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 26,556 (0.44)/18,608 

Pacific white-sided 

dolphin.

Lagenorhynchus 

obliquidens.

California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 26,814 (0.28)/21,195 

Pantropical spotted dolphin.Stenella 

attenuata.

Oahu ..................

4-Islands ............

............................ ............................ Hawaii ................ ............................ unknown 

unknown 

Hawaii Island ..... ............................ ............................ Hawaii ................ ............................ unknown 

Hawaii Pelagic ... ............................ ............................ Hawaii ................ ............................ 15,917 (0.40)/11,508 

Pygmy killer whale Feresa attenuata Tropical .............. ............................ ............................ Southern California.Winter & Spring unknown 

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 3,433 (0.52)/2,274 

Risso’s dolphins ... Grampus griseus California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 6,336 (0.32)/4,817 

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 7,256 (0.41)/5,207 

Rough-toothed 

dolphin.

Steno 

bredanensis.

na 3 ..................... ............................ ............................ Southern California............................. unknown 

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 6,288 (0.39)/4,581 


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TABLE 13—MARINE MAMMALS OCCURRENCE WITHIN THE HSTT STUDY AREA—Continued 

Common name Scientific name Stock 

Status 

Occurrence Seasonal absence 

Stock abundance 

(CV)/minimum 

MMPA ESA population 

Short-beaked 

common dolphin.

Delphinus delphis.California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 969,861 (0.17)/839,325 

Short-finned pilot 

whale.

Globicephala 

macrorhynchus.

California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 836 (0.79)/466 

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 12,422 (0.43)/8,782 

Spinner dolphin .... Stenella 

longirostris.

Hawaii Pelagic ...

Hawaii Island .....

............................ ............................ Hawaii ................ ............................ unknown 

631 (0.04)/585 

Oahu and 4-Islands............................. ............................ Hawaii ................ ............................ 355 (0.09)/329 

Kauai and Niihau ............................ ............................ Hawaii ................ ............................ 601 (0)/509 

Kure and Midway ............................ ............................ Hawaii ................ ............................ unknown 

Pearl and Hermes............................. ............................ Hawaii ................ ............................ unknown 

Striped dolphin ..... Stenella 

coeruleoalba.

California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 29,211 (0.20)/24,782 

Hawaiian ............ ............................ ............................ Hawaii ................ ............................ 20,650 (0.36)/15,391 

Dall’s porpoise ..... Phocoenoides 

dalli.

California, Oregon, and 

Washington.

............................ ............................ Southern California............................. 25,750 (0.45)/17,954 

Harbor seal .......... Phoca vitulina .... California ............ ............................ ............................ Southern California............................. 30,968 na/27,348 

Hawaiian monk 

seal.

Neomonachus 

schauinslandi.

Hawaiian ............ Depleted ............ Endangered ....... Hawaii ................ ............................ 1,272 na/1,205 

Northern elephant 

seal.

Mirounga 

angustirostris.

California ............ ............................ ............................ Southern California............................. 179,000 na/81,368 

California sea lion Zalophus 

californianus.

U.S. Stock .......... ............................ ............................ Southern California............................. 296,750 na/153,337 

Guadalupe fur 

seal.

Arctocephalus 

townsendi.

Mexico to California.Depleted ............ Threatened ........ Southern California............................. 20,000 na/15,830 

Northern fur seal .. Callorhinus 

ursinus.

California ............ ............................ ............................ Southern California............................. 14,050 na/7,524 

Notes: 

1The two humpback whale Distinct Population Segments making up the California, Oregon, and Washington stock present in Southern California are the Mexico 

Distinct Population Segment, listed under ESA as Threatened, and the Central America Distinct Population Segment, which is listed under ESA as Endangered. 2This stock is mentioned briefly in the Pacific Stock Assessment Report (Carretta et al., 2017) and referred to as the ‘‘Eastern North Pacific Transient’’ stock; however, the Alaska Stock Assessment Report contains assessments of all transient killer whale stocks in the Pacific and the Alaska Stock Assessment Report refers to 

this same stock as the ‘‘West Coast Transient’’ stock (Muto et al., 2017). 3 Rough-toothed dolphin has a range known to include the waters off Southern California, but there is no recognized stock or data available for the U.S west coast. 

Below, we include additional 

information about the marine mammals 

in the area of the Specified Activities, 

where available, that will inform our 

analysis, such as identifying areas of 

important habitat or known behaviors, 

or where Unusual Mortality Events 

(UME) have been designated. 

Critical Habitat 

Currently there is one marine 

mammal, the ESA-listed Hawaiian 

monk seal, with designated critical 

habitat within the HSTT Study Area. 

However, critical habitat for ESA-listed 

Main Hawaiian Islands insular false 

killer whale was recently proposed in 

November 2017 (82 FR 51186; 

November 3, 2017), designating waters 

from the 45 m depth contour to the 3200 

m depth contour around the main 

Hawaiian Islands from Niihau east to 

Hawaii. However, some areas were 

proposed for exclusion based on 

considerations of economic and national 

security impacts. 

Critical habitat for Hawaiian monk 

seals was designated in 1986 (51 FR 

16047; April 30, 1986) and later revised 

in 1988 (53 FR 18988; May 26, 1988) 

and in 2015 (80 FR 50925; August 21, 

2015) (NOAA, 2015a) (Figure 4–1 of the 

Navy’s application). The essential 

features of the critical habitat were 

identified as: (1) Adjacent terrestrial and 

aquatic areas with characteristics 

preferred by monk seals for pupping 

and nursing; (2) shallow, sheltered 

aquatic areas adjacent to coastal 

locations preferred by monk seals for 

pupping and nursing; (3) marine areas 

from 0 to 500 m in depth preferred by 

juvenile and adult monk seals for 

foraging; (4) areas with low levels of 

anthropogenic disturbance; (5) marine 

areas with adequate prey quantity and 

quality; and (6) significant areas used by 

monk seals for hauling out, resting, or 

molting (NOAA, 2015a). 

In the Northwestern Hawaiian Islands 

Hawaiian monk seal critical habitat 

includes all beach areas, sand spits and 

islets, including all beach crest 

vegetation to its deepest extent inland as 

well as the seafloor and marine habitat 

10 m in height above the seafloor from 

the shoreline out to the 200 m depth 

contour around Kure Atoll, Midway 

Atoll, Pearl and Hermes Reef, Lisianski 

Island, Laysan Island, Maro Reef, 

Gardner Pinnacles, French Frigate 

Shoals, Necker Island and Nihoa Island. 

In the main Hawaiian Islands, Hawaiian 

monk seal critical habitat includes the 

seafloor and marine habitat to 10 m 

above the seafloor from the 200 m depth 

contour through the shoreline and 

extending into terrestrial habitat 5 m 

inland from the shoreline between 

identified boundary points around 

Kaula Island (includes marine habitat 

only, some excluded areas see areas, 

Niihau (includes marine habitat from 10 

m–200 m in depth; some excluded 

areas), Kauai, Oahu, Maui Nui 

(including Kahoolawe, Lanai, Maui, and 

Molokai), Hawaii. 

The approximate area encompassed 

by the Northwestern Hawaiian Islands 

was designated as the 

Papahanaumokuakea Monument in 

2006, in part to protect the habitat of the 

Hawaiian monk seal. Hawaiian monk 

seals are managed as a single stock. 

There are six main reproductive 

subpopulations at: French Frigate 

Shoals, Laysan Island, Lisianski Island, 


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Pearl and Hermes Reef, Midway Island, 

and Kure Atoll in the northwestern 

Hawaiian Islands. 

Biologically Important Areas 

Biologically Important Areas (BIAs) 

include areas of known importance for 

reproduction, feeding, or migration, or 

areas where small and resident 

populations are known to occur (Van 

Parijs, 2015). Unlike critical habitat, 

these areas are not formally designated 

pursuant to any statute or law, but are 

a compilation of the best available 

science intended to inform impact and 

mitigation analyses. An interactive map 

of the BIAs may be found here: https:// 

cetsound.noaa.gov/biologicallyimportant-area-map. 

In Hawaii, 21 BIAs fall within or 

overlap with the HSTT Study Area. 

These include 11 small and resident 

population areas for species including 

dwarf sperm whales, Blainville’s beaked 

whales, Cuvier’s beaked whales, pygmy 

killer whales, short-finned pilot whales, 

melon-headed whales, false killer 

whales, pantropical spotted dolphins, 

spinner dolphins, rough-toothed 

dolphins, and common bottlenose 

dolphins (see Appendix K of the HSTT 

DEIS/OEIS for figures depicting these 

areas). In addition, six non-contiguous 

areas located adjacent to the eight main 

Hawaiian Islands have been designated 

as a humpback whale reproductive BIA 

(Baird et al., 2015c). 

Five of the 28 BIAs that were 

identified for four species off the U.S. 

west coast (Calambokidis et al., 2015a) 

are located within or overlapping the 

SOCAL portion of the Study Area (see 

Appendix K of the HSTT DEIS/OEIS for 

figures depicting these areas). These 

identified areas include four feeding 

areas for blue whales and a migration 

area for gray whales (Calambokidis et 

al., 2015a). 

Main Hawaiian Islands Humpback 

Whale Reproduction BIA 

A single biologically important area 

around and between portions of eight 

islands was identified for breeding 

humpback whales in the Main Hawaiian 

Islands from December through April 

(Baird et al., 2015a) (see Figure K.3–1 of 

the HSTT DEIS/OEIS). The Main 

Hawaiian Islands Humpback Whale 

Reproduction BIA contains several 

humpback whale breeding sub-areas off 

the coasts of Kauai, Niihau, Oahu, Maui, 

and Hawaii Island. The highest 

densities of whales occur in waters that 

are less than 200 m in depth. The Main 

Hawaiian Islands Humpback Whale 

Reproduction Area also overlaps the 

Navy’s 4-Islands Region and Hawaii 

Island Mitigation Areas and Humpback 

Whale Special Reporting Areas 

described later in this document (and 

also shown in Appendix K of the HSTT 

DEIS/OEIS). The Main Hawaiian Islands 

Humpback Whale Reproduction BIA 

also encompasses the entire Humpback 

Whale National Marine Sanctuary. 

Dwarf Sperm Whales Small and 

Resident Population 

A year-round BIA has been identified 

for a small resident population of dwarf 

sperm whales located off the island of 

Hawaii (Mahaffy et al., 2009; Baird et 

al., 2013a) with sightings between 500 

and 1,000 m in depth (Baird et al., 

2013a). This BIA also overlaps the 

Navy’s Hawaii Island Mitigation Area 

described later in this document. 

Blainville’s Beaked Whales Small and 

Resident Population 

A year-round BIA for a small resident 

population of Blainville’s beaked 

whales has been identified off the island 

of Hawaii (McSweeney et al., 2007; 

Schorr et al., 2009a) with the highest 

density of groups in water between 500 

and 1,500 m in depth, and density 

decreasing offshore (Baird et al., 2015c). 

This BIA also overlaps the Navy’s 

Hawaii Island Mitigation Area described 

later in this document. 

Cuvier’s Beaked Whales Small and 

Resident Population 

A year-round BIA for a small resident 

population of Cuvier’s beaked whales 

has been identified off the island of 

Hawaii with the highest density of 

groups in water between 1,500 and 

4,000 m in depth, and density 

decreasing offshore (Baird et al., 2015c). 

This BIA also mostly overlaps the 

Navy’s Hawaii Island Mitigation Area 

described later in this document. 

Pygmy Killer Whales Small and 

Resident Population 

A year-round BIA for a small resident 

population of pygmy killer whales has 

been identified for the Hawaii Island 

resident population. This BIA includes 

the west side of the island of Hawaii, 

from northwest of Kawaihae south to 

the south point of the island, and along 

the southeast coast of the island. This 

BIA also overlaps the Navy’s Hawaii 

Island Mitigation Area described later in 

this document. 

Short-Finned Pilot Whales Small and 

Resident Population 

A year- round BIA for a small resident 

population of short-finned pilot whales 

has been identified off the island of 

Hawaii (Baird et al., 2011c, 2013a; 

Mahaffy, 2012). Short-finned pilot 

whales are primarily connected to slope 

habitats off the islands, with the highest 

density between 1,000 and 2,500 m in 

depth, dropping off significantly after 

2,500 m (Baird et al., 2013a). This BIA 

also overlaps the Navy’s Hawaii Island 

Mitigation Area described later in this 

document. 

Melon-Headed Whales Small and 

Resident Population 

A year-round BIA has been identified 

for a small and resident population of 

melon-headed whales off the island of 

Hawaii, primarily using the Kohala area. 

This BIA also overlaps the Navy’s 

Hawaii Island Mitigation Area described 

later in this document. 

False Killer Whales Small and Resident 

Population 

A year-round BIA has been identified 

for a small and resident insular 

population of false killer whales off the 

coasts of Oahu, Maui, Molokai, Lanai, 

and Hawaii Island. The known range of 

this population extends from west of 

Niihau to east of Hawaii, out to 122 km 

offshore (Baird et al., 2012). This BIA 

also partially overlap the Navy’s 4- 

Islands Region and Hawaii Island 

Mitigation Areas described later in this 

document. 

Pantropical Spotted Dolphins Small and 

Resident Populations 

Three year-round BIAs have been 

identified for small and resident 

populations of pantropical spotted 

dolphin. Three stocks of this species 

occurs around the main Hawaiian 

Islands (Oahu, the 4-Island Region, and 

off the main island of Hawaii). Two of 

these BIAs also overlap the Navy’s 4- 

Islands Region and Hawaii Island 

Mitigation Areas described later in this 

document. 

Spinner Dolphins Small and Resident 

Populations 

Year-round BIAs have been identified 

for five small and resident populations 

of spinner dolphins. The boundaries of 

these populations are out to 10 nmi 

from shore around Kure and Midway 

Atolls, Pearl and Hermes Reef, Kauai 

and Niihau, Oahu and the 4-Islands 

Region and off the main island of 

Hawaii (Carretta et al., 2014). Two of 

these BIAs also overlap the Navy’s 4- 

Islands Region and Hawaii Island 

Mitigation Areas described later in this 

document. 

Rough-Toothed Dolphins Small and 

Resident Population 

A year-round BIA has been identified 

for a small demographically isolated 

resident population off the island of 

Hawaii (Baird et al., 2008a; Albertson, 


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2015). This species is also found 

elsewhere among the Hawaiian Islands. 

The Navy’s Hawaii Island Mitigation 

Area also overlaps with the majority of 

this BIA described later in this 

document. 

Common Bottlenose Dolphins Small 

and Resident Populations 

Year-round BIAs have been identified 

for the four insular stocks of bottlenose 

dolphins in Hawaiian waters. They are 

found both nearshore and offshore areas 

(Barlow, 2006), but around the main 

Hawaiian Islands they are primarily 

found in depths of less than 1,000 m 

(Baird et al., 2013a). The Navy’s 4- 

Islands Region Mitigation Area overlaps 

portions of the BIA off of Molokai, 

Maui, and Lanai and the Hawaii Island 

Mitigation Area (described later in this 

document) includes the entire BIA off of 

the Island of Hawaii. 

Blue Whale Feeding BIAs 

There are nine feeding area BIAs 

identified for blue whales off the U.S. 

west coast (Calambokidis et al., 2015a), 

but only four overlap with the SOCAL 

portion of the HSTT Study Area (see 

Figure K.4–1 of the HSTT DEIS/OEIS). 

Two of these feeding areas (the Santa 

Monica Bay to Long Beach and the San 

Nicolas Island feeding area BIAs) are at 

the extreme northern edge and slightly 

overlap with the SOCAL portion of the 

HSTT Study Area. The remaining two 

feeding areas (the Tanner-Cortes Bank 

and the San Diego feeding area BIAs) are 

entirely within the SOCAL portion of 

the HSTT Study Area (Calambokidis et 

al., 2015a). The feeding behavior for 

which these areas are designated occurs 

from June to October (Aquatic 

Mammals, 2015; Calambokidis et al., 

2015a). The San Diego blue whale 

feeding area overlaps with the Navy’s 

San Diego Arc Mitigation Area as 

described later in this document. 

Gray Whale Migration BIA 

Calambokidis et al. (2015) identified a 

gray whale migration area off Southern 

California and overlapping with all the 

Southern California portion of the HSTT 

Study Area north of the border with 

Mexico (Figure K.4–7). This migration 

area covers approximately 22,300 km 2

of water space within the HSTT Study 

Area. 

National Marine Sanctuaries 

Under Title III of the Marine 

Protection, Research, and Sanctuaries 

Act of 1972 (also known as the National 

Marine Sanctuaries Act (NMSA)), 

NOAA can establish as national marine 

sanctuaries (NMS), areas of the marine 

environment with special conservation, 

recreational, ecological, historical, 

cultural, archaeological, scientific, 

educational, or aesthetic qualities. 

Sanctuary regulations prohibit 

destroying, causing the loss of, or 

injuring any sanctuary resource 

managed under the law or regulations 

for that sanctuary (15 CFR part 922). 

NMS are managed on a site-specific 

basis, and each sanctuary has sitespecific regulations. Most, but not all 

sanctuaries have site-specific regulatory 

exemptions from the prohibitions for 

certain military activities. Separately, 

section 304(d) of the NMSA requires 

Federal agencies to consult with the 

Office of National Marine Sanctuaries 

whenever their Specified Activities are 

likely to destroy, cause the loss of, or 

injure a sanctuary resource. There are 

two national marine sanctuaries 

managed by the Office of National 

Marine Sanctuaries within the Study 

Area, the Hawaiian Islands Humpback 

Whale NMS and Channel Islands NMS 

(see Table 6.1–2 and Figures 6.1–3 and 

6.1–4 of the HSTT DEIS/OEIS), which 

are described below. 

Hawaiian Islands Humpback Whale 

NMS 

The Hawaiian Islands Humpback 

Whale NMS is a single-species managed 

sanctuary, composed of 1,035 nmi2 of 

the waters around Maui, Lanai, and 

Molokai; and smaller areas off the north 

shore of Kauai, off Hawaii’s west coast, 

and off the north and southeast coasts 

of Oahu. The Sanctuary is entirely 

within the HRC of the HSTT Study Area 

and constitutes one of the world’s most 

important Hawaii humpback whale 

Distinct Population Segment (DPS) 

habitats (81 FR 62259; September 8, 

2016), and is a primary region for 

humpback reproduction in the United 

States (National Marine Sanctuaries 

Program, 2002). Scientists estimate that 

more than 50 percent of the entire North 

Pacific humpback whale population 

migrates to Hawaiian waters each winter 

to mate, calve, and nurse their young. 

The North Pacific humpback whale 

population has been split into two 

DPSs. The Hawaii humpback whale DPS 

migrates to Hawaiian waters each winter 

and is not listed under the ESA. In 

addition to protection under the MMPA, 

the Hawaii humpback whale DPS is 

protected in sanctuary waters by the 

Hawaiian Islands NMS. The sanctuary 

was created to protect humpback whales 

and shallow, protected waters important 

for calving and nursing (Office of 

National Marine Sanctuaries, 2010). 

The Hawaiian Islands Humpback 

Whale NMS overlaps with the Main 

Hawaiian Islands Humpback Whale 

Reproduction Area (BIA) identified in 

Van Parijs (2015) and Baird et al. (2015) 

(shown in Figure K.3–1 of Appendix K 

and as discussed in Appendix K, 

Section K.3.1 (Main Hawaiian Islands 

Humpback Whale Reproduction Area of 

the HSTT DEIS/OEIS)). 

Channel Islands NMS 

The Channel Islands NMS is an 

ecosystem-based managed sanctuary 

consisting of an area of 1,109 nmi 2

around Anacapa Island, Santa Cruz 

Island, Santa Rosa Island, San Miguel 

Island, and Santa Barbara Island to the 

south. Only 92 nmi 2, or about 8 percent 

of the sanctuary, occurs within the 

SOCAL portion of the Study Area (see 

Figure 6.1–4 of the HSTT DEIS/OEIS). 

The Study Area overlaps with the 

sanctuary at Santa Barbara Island. In 

addition, the Navy has proposed to 

implement the Santa Barbara Island 

Mitigation Area around Santa Barbara 

Island out to 6 nmi as described later in 

this document (also see Section K.2.2, 

Mitigation Areas to be Implemented of 

the HSTT DEIS/OEIS). As an ecosystembased managed sanctuary, key habitats 

include kelp forest, surfgrass and 

eelgrass, intertidal zone, nearshore 

subtidal, deepwater benthic, and water 

column habitat. The diversity of habitats 

onshore and offshore contributes to the 

high species diversity in the Channel 

Islands NMS, with more than 195 

species of birds, at least 33 species of 

cetaceans, 4 species of sea turtles, at 

least 492 species of algae and 4 species 

of sea grasses, a variety of invertebrates 

(including two endangered species 

(black abalone and the white abalone)), 

and 481 species of fish (NMS, 2009b). 

Unusual Mortality Events (UME) 

A UME is defined under Section 

410(6) of the MMPA as a stranding that 

is unexpected; involves a significant 

die-off of any marine mammal 

population; and demands immediate 

response. From 1991 to the present, 

there have been 16 formally recognized 

UMEs affecting marine mammals in 

California and Hawaii and involving 

species under NMFS’s jurisdiction. Two 

UMEs that could be relevant to 

informing the current analysis are 

discussed below. Specifically, the 

California sea lion UME in California is 

still open, but will be closed soon. The 

Guadalupe fur seal UME in California is 

still active and involves an ongoing 

investigation. 

California Sea Lion UME 

Elevated strandings of California sea 

lion pups began in Southern California 

in January 2013. In 2013, over 1,600 

California sea lions stranded alive along 

the Southern California coastline and 


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over 3,500 live stranded California sea 

lions stranded on beaches in 2015, 

which was the highest number on 

record. Approximately 13,000 California 

sea lions (both live and dead) stranded 

from January 1, 2013, through December 

31, 2017. Strandings in 2017 have 

finally returned to baseline 

(approximately 1,400/yr). The UME is 

currently defined to include pup and 

yearling California sea lions (0–2 years 

of age). Many of the sea lions were 

emaciated, dehydrated, and very 

underweight for their age. Findings to 

date indicate that a likely contributor to 

the large number of stranded, 

malnourished pups was a change in the 

availability of sea lion prey, especially 

sardines, a high value food source for 

both weaned pups and nursing mothers. 

Current data show changes in 

availability of sea lion prey in Southern 

California waters was likely a 

contributor to the UME, and this change 

was most likely secondary to ecological 

factors (El Nin ̃ o and Warm Water Blob). 

Sardine spawning grounds shifted 

further offshore in 2012 and 2013, and 

while other prey were available (market 

squid and rockfish), these may not have 

provided adequate nutrition in the milk 

of sea lion mothers supporting pups or 

for newly-weaned pups foraging on 

their own. Although the pups showed 

signs of some viruses and infections, 

findings indicate that this event was not 

caused by disease, but rather by the lack 

of high quality, close-by food sources for 

nursing mothers and weaned pups. 

Current evidence does not support that 

this UME was caused by a single 

infectious agent, though a variety of 

disease-causing bacteria and viruses 

were found in samples from sea lion 

pups. This investigation will soon be 

closed. Please refer to https://

www.fisheries.noaa.gov/national/ 

marine-life-distress/2013-2017- 

california-sea-lion-unusual-mortalityevent-california for more information on 

this UME. 

Guadalupe Fur Seal UME 

Increased strandings of Guadalupe fur 

seals began along the entire coast of 

California in January 2015 and were 

eight times higher than the historical 

average (approximately 10 seals/yr). 

Strandings have continued since 2015 

and have remained well above average 

through 2017. As of March 8, 2018, the 

total number of Guadalupe fur seals to 

date in the UME is 241. Strandings are 

seasonal and generally peak in April 

through June of each year. The 

Guadalupe fur seal strandings have been 

mostly weaned pups and juveniles (1– 

2 years old) with both live and dead 

strandings occurring. Current findings 

from the majority of stranded animals 

include primary malnutrition with 

secondary bacterial and parasitic 

infections. This UME is occurring in the 

same area as the ongoing 2013–2017 

California sea lion UME. This 

investigation is ongoing. Please refer to 

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

national/marine-life-distress/2015-2018- 

guadalupe-fur-seal-unusual-mortalityevent-california for more information on 

this UME. 

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. Current data indicate 

that 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) 

recommended that marine mammals be 

divided into functional hearing groups 

based on directly measured or estimated 

hearing ranges on the basis of available 

behavioral response data, audiograms 

derived using auditory evoked potential 

techniques, anatomical modeling, and 

other data. Note that no direct 

measurements of hearing ability have 

been successfully completed for 

mysticetes (i.e., low-frequency 

cetaceans). Subsequently, NMFS (2016) 

described generalized hearing ranges for 

these marine mammal hearing groups. 

Generalized hearing ranges were chosen 

based on the approximately 65 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. The 

functional groups and the associated 

frequencies are indicated below (note 

that these frequency ranges correspond 

to the range for the composite group, 

with the entire range not necessarily 

reflecting the capabilities of every 

species within that group): 

• Low-frequency cetaceans 

(mysticetes): Generalized hearing is 

estimated to occur between 

approximately 7 Hz and 35 kHz; 

• Mid-frequency cetaceans (larger 

toothed whales, beaked whales, and 

most delphinids): Generalized hearing is 

estimated to occur between 

approximately 150 Hz and 160 kHz; 

• High-frequency cetaceans 

(porpoises, river dolphins, and members 

of the genera Kogia and 

Cephalorhynchus; including two 

members of the genus Lagenorhynchus, 

on the basis of recent echolocation data 

and genetic data): Generalized hearing is 

estimated to occur between 

approximately 275 Hz and 160 kHz; 

• Pinnipeds in water; Phocidae (true 

seals): Generalized hearing is estimated 

to occur between approximately 50 Hz 

to 86 kHz; and 

• Pinnipeds in water; Otariidae (eared 

seals): Generalized hearing is estimated 

to occur between 60 Hz and 39 kHz. 

The pinniped functional 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 and Holt, 2013). 

For more detail concerning these 

groups and associated frequency ranges, 

please see NMFS (2016) for a review of 

available information. 

Potential Effects of Specified Activities 

on Marine Mammals and Their Habitat 

This section includes a summary and 

discussion of the ways that components 

of the specified activity may impact 

marine mammals and their habitat. The 

‘‘Estimated Take of Marine Mammals’’ 

section later in this document includes 

a quantitative analysis of the number of 

instances of take that could occur from 

these activities. 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 how those impacts 

on individuals are likely to impact 

marine mammal species or stocks. 

The Navy has requested authorization 

for the take of marine mammals that 

may occur incidental to training and 

testing activities in the HSTT Study 

Area. The Navy analyzed potential 

impacts to marine mammals from 

acoustic and explosive sources as well 

as vessel strikes. 

Other potential impacts to marine 

mammals from training and testing 

activities in the HSTT Study Area were 

analyzed in the HSTT DEIS/OEIS, in 

consultation with NMFS as a 

cooperating agency, and determined to 

be unlikely to result in marine mammal 

take. Therefore, the Navy has not 

requested authorization for take of 

marine mammals incidental to other 

components of their Specified 

Activities, and we agree that take is 


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unlikely to occur from those 

components. In this proposed rule, 

NMFS analyzes the potential effects on 

marine mammals from the activity 

components that may cause the take of 

marine mammals: Exposure to acoustic 

or explosive stressors including nonimpulsive (sonar and other active 

acoustic sources) and impulsive 

(explosives, impact pile driving, and air 

guns) stressors, and vessel strikes. 

For the purpose of MMPA incidental 

take authorizations, NMFS’s effects 

assessments serve four primary 

purposes: (1) To prescribe the 

permissible methods of taking (i.e., 

Level B harassment (behavioral 

harassment and temporary threshold 

shift (TTS), Level A harassment 

(permanent threshold shift (PTS) or 

non-auditory injury), serious injury, or 

mortality, including an identification of 

the number and types of take that could 

occur by harassment, serious injury, or 

mortality) and to prescribe other means 

of effecting the least practicable adverse 

impact on such species or stock and its 

habitat (i.e., mitigation); (2) to determine 

whether the specified activities would 

have a negligible impact on the affected 

species or stocks of marine mammals 

(based on the likelihood that the 

activities would adversely affect the 

species or stock through effects on 

annual rates of recruitment or survival); 

(3) to determine whether the specified 

activities would have an unmitigable 

adverse impact on the availability of the 

species or stock(s) for subsistence uses 

(however, there are no subsistence 

communities that would be affected in 

the HSTT Study Area, so this 

determination is inapplicable to the 

HSTT rulemaking); and (4) to prescribe 

requirements pertaining to monitoring 

and reporting. 

In the Potential Effects Section, NMFS 

provides a general description of the 

ways marine mammals may be affected 

by these activities in the form of 

mortality, physical trauma, sensory 

impairment (permanent and temporary 

threshold shifts and acoustic masking), 

physiological responses (particular 

stress responses), behavioral 

disturbance, or habitat effects. 

Explosives and vessel strikes, which 

have the potential to result in incidental 

take from serious injury and/or 

mortality, will be discussed in more 

detail in the Estimated Take of Marine 

Mammals section. The Estimated Take 

of Marine Mammals section also 

discusses how the potential effects on 

marine mammals from non-impulsive 

and impulsive sources relate to the 

MMPA definitions of Level A and Level 

B Harassment, and quantifies those 

effects that rise to the level of a take 

along with the potential effects from 

vessel strikes. The Negligible Impact 

Analysis Section assesses whether the 

proposed authorized take will have a 

negligible impact on the affected species 

and stocks. 

Potential Effects of Underwater Sound 

Note that, in the following discussion, 

we refer in many cases to a review 

article concerning studies of noiseinduced hearing loss conducted from 

1996–2015 (i.e., Finneran, 2015). For 

study-specific citations, please see that 

work. Anthropogenic sounds cover a 

broad range of frequencies and sound 

levels and can have a range of highly 

variable impacts on marine life, from 

none or minor to potentially severe 

responses, depending on received 

levels, duration of exposure, behavioral 

context, and various other factors. The 

potential effects of underwater sound 

from active acoustic sources can 

possibly result in one or more of the 

following: temporary or permanent 

hearing impairment, non-auditory 

physical or physiological effects, 

behavioral disturbance, stress, and 

masking (Richardson et al., 1995; 

Gordon et al., 2004; Nowacek et al., 

2007; Southall et al., 2007; Go ̈tz et al., 

2009). The degree of effect is 

intrinsically related to the signal 

characteristics, received level, distance 

from the source, and duration of the 

sound exposure. In general, sudden, 

high level sounds can cause hearing 

loss, as can longer exposures to lower 

level sounds. Temporary or permanent 

loss of hearing will occur almost 

exclusively for noise within an animal’s 

hearing range. We first describe specific 

manifestations of acoustic effects before 

providing discussion specific to the 

Navy’s activities. 

Richardson et al. (1995) described 

zones of increasing intensity of effect 

that might be expected to occur, in 

relation to distance from a source and 

assuming that the signal is within an 

animal’s hearing range. First is the area 

within which the acoustic signal would 

be audible (potentially perceived) to the 

animal, but not strong enough to elicit 

any overt behavioral or physiological 

response. The next zone corresponds 

with the area where the signal is audible 

to the animal and of sufficient intensity 

to elicit behavioral or physiological 

responsiveness. Third is a zone within 

which, for signals of high intensity, the 

received level is sufficient to potentially 

cause discomfort or tissue damage to 

auditory systems. Overlaying these 

zones to a certain extent is the area 

within which masking (i.e., when a 

sound interferes with or masks the 

ability of an animal to detect a signal of 

interest that is above the absolute 

hearing threshold) may occur; the 

masking zone may be highly variable in 

size. 

We also describe more severe effects 

(i.e., certain non-auditory physical or 

physiological effects). Potential effects 

from impulsive sound sources can range 

in severity from effects such as 

behavioral disturbance or tactile 

perception to physical discomfort, slight 

injury of the internal organs and the 

auditory system, or mortality (Yelverton 

et al., 1973). Non-auditory physiological 

effects or injuries that theoretically 

might occur in marine mammals 

exposed to high level underwater sound 

or as a secondary effect of extreme 

behavioral reactions (e.g., change in 

dive profile as a result of an avoidance 

reaction) caused by exposure to sound 

include neurological effects, bubble 

formation, resonance effects, and other 

types of organ or tissue damage (Cox et 

al., 2006; Southall et al., 2007; Zimmer 

and Tyack, 2007; Tal et al., 2015). 

Acoustic Sources 

Direct Physiological Effects 

Based on the literature, there are two 

basic ways that non-impulsive sources 

might directly result in direct 

physiological effects. Noise-induced 

loss of hearing sensitivity (more 

commonly-called ‘‘threshold shift’’ (TS)) 

is the better-understood of these two 

effects, and the only one that is actually 

expected to occur. The second effect, 

acoustically mediated bubble growth 

and other pressure-related physiological 

impacts are addressed briefly below, but 

are not expected to result from the 

Navy’s activities. Separately, an 

animal’s behavioral reaction to an 

acoustic exposure might lead to 

physiological effects that might 

ultimately lead to injury or death, which 

is discussed later in the Stranding 

Section. 

Threshold Shift (Noise-Induced Loss of 

Hearing) 

When animals exhibit reduced 

hearing sensitivity within their auditory 

range (i.e., sounds must be louder for an 

animal to detect them) following 

exposure to a sufficiently intense sound 

or a less intense sound for a sufficient 

duration, it is referred to as a noiseinduced TS. An animal can experience 

a TTS and/or PTS. TTS can last from 

minutes or hours to days (i.e., there is 

recovery back to baseline/pre-exposure 

levels), can occur within a specific 

frequency range (i.e., an animal might 

only have a temporary loss of hearing 

sensitivity within a limited frequency 

band of its auditory range), and can be 


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of varying amounts (for example, an 

animal’s hearing sensitivity might be 

reduced by only 6 dB or reduced by 30 

dB). Repeated sound exposure that leads 

to TTS could cause PTS. In severe cases 

of PTS, there can be total or partial 

deafness, while in most cases the animal 

has an impaired ability to hear sounds 

in specific frequency ranges (Kryter, 

1985). When PTS occurs, there is 

physical damage to the sound receptors 

in the ear (i.e., tissue damage), whereas 

TTS represents primarily tissue fatigue 

and is reversible (Southall et al., 2007). 

PTS is permanent (i.e., there is 

incomplete recovery back to baseline/ 

pre-exposure levels), but also can occur 

in a specific frequency range and 

amount as mentioned above for TTS. In 

addition, other investigators have 

suggested that TTS is within the normal 

bounds of physiological variability and 

tolerance and does not represent 

physical injury (e.g., Ward, 1997). 

Therefore, NMFS does not consider TTS 

to constitute auditory injury. 

The following physiological 

mechanisms are thought to play a role 

in inducing auditory TS: Effects to 

sensory hair cells in the inner ear that 

reduce their sensitivity; modification of 

the chemical environment within the 

sensory cells; residual muscular activity 

in the middle ear; displacement of 

certain inner ear membranes; increased 

blood flow; and post-stimulatory 

reduction in both efferent and sensory 

neural output (Southall et al., 2007). 

The amplitude, duration, frequency, 

temporal pattern, and energy 

distribution of sound exposure all can 

affect the amount of associated TS and 

the frequency range in which it occurs. 

Generally, the amount of TS, and the 

time needed to recover from the effect, 

increase as amplitude and duration of 

sound exposure increases. Human nonimpulsive noise exposure guidelines are 

based on the assumption that exposures 

of equal energy (the same SEL) produce 

equal amounts of hearing impairment 

regardless of how the sound energy is 

distributed in time (NIOSH, 1998). 

Previous marine mammal TTS studies 

have also generally supported this equal 

energy relationship (Southall et al., 

2007). However, some more recent 

studies concluded that for all noise 

exposure situations the equal energy 

relationship may not be the best 

indicator to predict TTS onset levels 

(Mooney et al., 2009a and 2009b; Kastak 

et al., 2007). These studies highlight the 

inherent complexity of predicting TTS 

onset in marine mammals, as well as the 

importance of considering exposure 

duration when assessing potential 

impacts. Generally, with sound 

exposures of equal energy, those that 

were quieter (lower SPL) with longer 

duration were found to induce TTS 

onset at lower levels than those of 

louder (higher SPL) and shorter 

duration. Less TS will occur from 

intermittent sounds than from a 

continuous exposure with the same 

energy (some recovery can occur 

between intermittent exposures) (Kryter 

et al., 1966; Ward, 1997; Mooney et al., 

2009a, 2009b; Finneran et al., 2010). For 

example, one short but loud (higher 

SPL) sound exposure may induce the 

same impairment as one longer but 

softer (lower SPL) sound, which in turn 

may cause more impairment than a 

series of several intermittent softer 

sounds with the same total energy 

(Ward, 1997). Additionally, though TTS 

is temporary, very prolonged or 

repeated exposure to sound strong 

enough to elicit TTS, or shorter-term 

exposure to sound levels well above the 

TTS threshold can cause PTS, at least in 

terrestrial mammals (Kryter, 1985; 

Lonsbury-Martin et al., 1987). 

PTS is considered auditory injury 

(Southall et al., 2007). Irreparable 

damage to the inner or outer cochlear 

hair cells may cause PTS; however, 

other mechanisms are also involved, 

such as exceeding the elastic limits of 

certain tissues and membranes in the 

middle and inner ears and resultant 

changes in the chemical composition of 

the inner ear fluids (Southall et al., 

2007). 

Although the published body of 

scientific literature contains numerous 

theoretical studies and discussion 

papers on hearing impairments that can 

occur with exposure to a loud sound, 

only a few studies provide empirical 

information on the levels at which 

noise-induced loss in hearing sensitivity 

occurs in nonhuman animals. The 

NMFS 2016 Acoustic Technical 

Guidance, which was used in the 

assessment of effects for this action, 

compiled, interpreted, and synthesized 

the best available scientific information 

for noise-induced hearing effects for 

marine mammals to derive updated 

thresholds for assessing the impacts of 

noise on marine mammal hearing, as 

noted above. For cetaceans, published 

data on the onset of TTS are limited to 

the captive bottlenose dolphin, beluga, 

harbor porpoise, and Yangtze finless 

porpoise (summarized in Finneran, 

2015). TTS studies involving exposure 

to other Navy activities (e.g., SURTASS 

LFA) or other low-frequency sonar 

(below 1 kHz) have never been 

conducted due to logistical difficulties 

of conducting experiments with low 

frequency sound sources. However, 

there are TTS measurements for 

exposures to other LF sources, such as 

seismic air guns. Finneran et al. (2015) 

suggest that the potential for air guns to 

cause hearing loss in dolphins is lower 

than previously predicted, perhaps as a 

result of the low-frequency content of 

air gun impulses compared to the highfrequency hearing ability of dolphins. 

Finneran et al. (2015) measured hearing 

thresholds in three captive bottlenose 

dolphins before and after exposure to 

ten pulses produced by a seismic air 

gun in order to study TTS induced after 

exposure to multiple pulses. Exposures 

began at relatively low levels and 

gradually increased over a period of 

several months, with the highest 

exposures at peak SPLs from 196 to 210 

dB and cumulative (unweighted) SELs 

from 193–195 dB. No substantial TTS 

was observed. In addition, behavioral 

reactions were observed that indicated 

that animals can learn behaviors that 

effectively mitigate noise exposures 

(although exposure patterns must be 

learned, which is less likely in wild 

animals than for the captive animals 

considered in the study). The authors 

note that the failure to induce more 

significant auditory effects was likely 

due to the intermittent nature of 

exposure, the relatively low peak 

pressure produced by the acoustic 

source, and the low-frequency energy in 

air gun pulses as compared with the 

frequency range of best sensitivity for 

dolphins and other mid-frequency 

cetaceans. For pinnipeds in water, 

measurements of TTS are limited to 

harbor seals, elephant seals, and 

California sea lions (summarized in 

Finneran, 2015). 

Marine mammal hearing plays a 

critical role in communication with 

conspecifics and in interpretation of 

environmental cues for purposes such 

as predator avoidance and prey capture. 

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 

a time when communication is critical 

for successful mother/calf interactions 

could have more serious impacts if it 


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were in the same frequency band as the 

necessary vocalizations and of a severity 

that impeded communication. The fact 

that animals exposed to high levels of 

sound that would be expected to result 

in this physiological response would 

also be expected to have behavioral 

responses of a comparatively more 

severe or sustained nature is potentially 

more significant than simple existence 

of a TTS. However, it is important to 

note that TTS could occur due to longer 

exposures to sound at lower levels so 

that a behavioral response may not be 

elicited. 

Depending on the degree and 

frequency range, the effects of PTS on 

an animal could also range in severity, 

although it is considered generally more 

serious than TTS because it is a 

permanent condition. Of note, 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., 2007), so we can 

infer that strategies exist for coping with 

this condition to some degree, though 

likely not without some cost to the 

animal. 

Acoustically Mediated Bubble Growth 

and Other Pressure-Related Injury 

One theoretical cause of injury to 

marine mammals is rectified diffusion 

(Crum and Mao, 1996), the process of 

increasing the size of a bubble by 

exposing it to a sound field. This 

process could be facilitated if the 

environment in which the ensonified 

bubbles exist is supersaturated with gas. 

Repetitive diving by marine mammals 

can cause the blood and some tissues to 

accumulate gas to a greater degree than 

is supported by the surrounding 

environmental pressure (Ridgway and 

Howard, 1979). The deeper and longer 

dives of some marine mammals (for 

example, beaked whales) are 

theoretically predicted to induce greater 

supersaturation (Houser et al., 2001b). If 

rectified diffusion were possible in 

marine mammals exposed to high-level 

sound, conditions of tissue 

supersaturation could theoretically 

speed the rate and increase the size of 

bubble growth. Subsequent effects due 

to tissue trauma and emboli would 

presumably mirror those observed in 

humans suffering from decompression 

sickness. 

It is unlikely that the short duration 

(in combination with the source levels) 

of sonar pings would be long enough to 

drive bubble growth to any substantial 

size, if such a phenomenon occurs. 

However, an alternative but related 

hypothesis has also been suggested: 

Stable bubbles could be destabilized by 

high-level sound exposures such that 

bubble growth then occurs through 

static diffusion of gas out of the tissues. 

In such a scenario the marine mammal 

would need to be in a gassupersaturated state for a long enough 

period of time for bubbles to become of 

a problematic size. Recent research with 

ex vivo supersaturated bovine tissues 

suggested that, for a 37 kHz signal, a 

sound exposure of approximately 215 

dB referenced to (re) 1 mPa would be 

required before microbubbles became 

destabilized and grew (Crum et al., 

2005). Assuming spherical spreading 

loss and a nominal sonar source level of 

235 dB re 1 mPa at 1 m, a whale would 

need to be within 10 m (33 ft) of the 

sonar dome to be exposed to such sound 

levels. Furthermore, tissues in the study 

were supersaturated by exposing them 

to pressures of 400–700 kilopascals for 

periods of hours and then releasing 

them to ambient pressures. Assuming 

the equilibration of gases with the 

tissues occurred when the tissues were 

exposed to the high pressures, levels of 

supersaturation in the tissues could 

have been as high as 400–700 percent. 

These levels of tissue supersaturation 

are substantially higher than model 

predictions for marine mammals 

(Houser et al., 2001; Saunders et al., 

2008). It is improbable that this 

mechanism is responsible for stranding 

events or traumas associated with 

beaked whale strandings because both 

the degree of supersaturation and 

exposure levels observed to cause 

microbubble destabilization are unlikely 

to occur, either alone or in concert. 

Yet another hypothesis 

(decompression sickness) has 

speculated that rapid ascent to the 

surface following exposure to a startling 

sound might produce tissue gas 

saturation sufficient for the evolution of 

nitrogen bubbles (Jepson et al., 2003; 

Fernandez et al., 2005; Ferna ́ndez et al., 

2012). In this scenario, the rate of ascent 

would need to be sufficiently rapid to 

compromise behavioral or physiological 

protections against nitrogen bubble 

formation. Alternatively, Tyack et al. 

(2006) studied the deep diving behavior 

of beaked whales and concluded that: 

‘‘Using current models of breath-hold 

diving, we infer that their natural diving 

behavior is inconsistent with known 

problems of acute nitrogen 

supersaturation and embolism.’’ 

Collectively, these hypotheses can be 

referred to as ‘‘hypotheses of 

acoustically mediated bubble growth.’’ 

Although theoretical predictions 

suggest the possibility for acoustically 

mediated bubble growth, there is 

considerable disagreement among 

scientists as to its likelihood (Piantadosi 

and Thalmann, 2004; Evans and Miller, 

2003; Cox et al., 2006; Rommel et al., 

2006). Crum and Mao (1996) 

hypothesized that received levels would 

have to exceed 190 dB in order for there 

to be the possibility of significant 

bubble growth due to supersaturation of 

gases in the blood (i.e., rectified 

diffusion). Work conducted by Crum et 

al. (2005) demonstrated the possibility 

of rectified diffusion for short duration 

signals, but at SELs and tissue 

saturation levels that are highly 

improbable to occur in diving marine 

mammals. To date, energy levels (ELs) 

predicted to cause in vivo bubble 

formation within diving cetaceans have 

not been evaluated (NOAA, 2002b). 

Jepson et al. (2003, 2005) and Fernandez 

et al. (2004, 2005, 2012) concluded that 

in vivo bubble formation, which may be 

exacerbated by deep, long-duration, 

repetitive dives may explain why 

beaked whales appear to be relatively 

vulnerable to MF/HF sonar exposures. It 

has also been argued that traumas from 

some beaked whale strandings are 

consistent with gas emboli and bubbleinduced tissue separations (Jepson et 

al., 2003); however, there is no 

conclusive evidence of this (Rommel et 

al., 2006). 

In 2009, Hooker et al. tested two 

mathematical models to predict blood 

and tissue tension N2 (PN2) using field 

data from three beaked whale species: 

northern bottlenose whales, Cuvier’s 

beaked whales, and Blainville’s beaked 

whales. The researchers aimed to 

determine if physiology (body mass, 

diving lung volume, and dive response) 

or dive behavior (dive depth and 

duration, changes in ascent rate, and 

diel behavior) would lead to differences 

in PN2 levels and thereby decompression 

sickness risk between species. 

In their study, they compared results 

for previously published time depth 

recorder data (Hooker and Baird, 1999; 

Baird et al., 2006, 2008) from Cuvier’s 

beaked whale, Blainville’s beaked 

whale, and northern bottlenose whale. 

They reported that diving lung volume 

and extent of the dive response had a 

large effect on end-dive PN2. Also, 

results showed that dive profiles had a 

larger influence on end-dive PN2 than 

body mass differences between species. 

Despite diel changes (i.e., variation that 

occurs regularly every day or most days) 

in dive behavior, PN2 levels showed no 

consistent trend. Model output 

suggested that all three species live with 

tissue PN2 levels that would cause a 

significant proportion of decompression 

sickness cases in terrestrial mammals. 

The authors concluded that the dive 

behavior of Cuvier’s beaked whale was 

different from both Blainville’s beaked 

whale, and northern bottlenose whale, 


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and resulted in higher predicted tissue 

and blood N2 levels (Hooker et al., 

2009) and suggested that the prevalence 

of Cuvier’s beaked whales stranding 

after naval sonar exercises could be 

explained by either a higher abundance 

of this species in the affected areas or by 

possible species differences in behavior 

and/or physiology related to MF active 

sonar (Hooker et al., 2009). 

Bernaldo de Quiros et al. (2012) 

showed that, among stranded whales, 

deep diving species of whales had 

higher abundances of gas bubbles 

compared to shallow diving species. 

Kvadsheim et al. (2012) estimated blood 

and tissue PN2 levels in species 

representing shallow, intermediate, and 

deep diving cetaceans following 

behavioral responses to sonar and their 

comparisons found that deep diving 

species had higher end-dive blood and 

tissue N2 levels, indicating a higher risk 

of developing gas bubble emboli 

compared with shallow diving species. 

Fahlmann et al. (2014) evaluated dive 

data recorded from sperm, killer, longfinned pilot, Blainville’s beaked and 

Cuvier’s beaked whales before and 

during exposure to low, as defined by 

the authors, (1–2 kHz) and mid (2–7 

kHz) frequency active sonar in an 

attempt to determine if either 

differences in dive behavior or 

physiological responses to sonar are 

plausible risk factors for bubble 

formation. The authors suggested that 

CO2 may initiate bubble formation and 

growth, while elevated levels of N2 may 

be important for continued bubble 

growth. The authors also suggest that if 

CO2 plays an important role in bubble 

formation, a cetacean escaping a sound 

source may experience increased 

metabolic rate, CO2 production, and 

alteration in cardiac output, which 

could increase risk of gas bubble emboli. 

However, as discussed in Kvadsheim et 

al. (2012), the actual observed 

behavioral responses to sonar from the 

species in their study (sperm, killer, 

long-finned pilot, Blainville’s beaked, 

and Cuvier’s beaked whales) did not 

imply any significantly increased risk of 

decompression sickness due to high 

levels of N2. Therefore, further 

information is needed to understand the 

relationship between exposure to 

stimuli, behavioral response (discussed 

in more detail below), elevated N2

levels, and gas bubble emboli in marine 

mammals. The hypotheses for gas 

bubble formation related to beaked 

whale strandings is that beaked whales 

potentially have strong avoidance 

responses to MF active sonars because 

they sound similar to their main 

predator, the killer whale (Cox et al., 

2006; Southall et al., 2007; Zimmer and 

Tyack, 2007; Baird et al., 2008; Hooker 

et al., 2009). Further investigation is 

needed to assess the potential validity of 

these hypotheses. 

To summarize, while there are several 

hypotheses, there is little data to 

support the potential for strong, 

anthropogenic underwater sounds to 

cause non-auditory physical effects in 

marine mammals. The available data do 

not support identification of a specific 

exposure level above which nonauditory effects can be expected 

(Southall et al., 2007) or any meaningful 

quantitative predictions of the numbers 

(if any) of marine mammals that might 

be affected in these ways. In addition, 

such effects, if they occur at all, would 

be expected to be limited to situations 

where marine mammals were exposed 

to high powered sounds at very close 

range over a prolonged period of time, 

which is not expected to occur based on 

the speed of the vessels operating sonar 

in combination with the speed and 

behavior of marine mammals in the 

vicinity of sonar. 

Acoustic Masking 

Sound can disrupt behavior through 

masking, or interfering 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 and Farmer, 2000; Tyack, 2000; 

Erbe et al., 2016). Masking occurs when 

the receipt of a sound is interfered with 

by another coincident sound at similar 

frequencies and at similar or higher 

intensity, and may occur whether the 

sound is natural (e.g., snapping shrimp, 

wind, waves, precipitation) or 

anthropogenic (e.g., shipping, sonar, 

seismic exploration) in origin. 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. Masking these 

acoustic signals can disturb the behavior 

of individual animals, groups of 

animals, or entire populations. 

In humans, significant masking of 

tonal signals occurs as a result of 

exposure to noise in a narrow band of 

similar frequencies. As the sound level 

increases, though, the detection of 

frequencies above those of the masking 

stimulus decreases also. This principle 

is expected to apply to marine mammals 

as well because of common 

biomechanical cochlear properties 

across taxa. 

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 

man-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; 

Matthews et al., 2016) 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, 

2009; 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 through other compensatory 

behaviors (Houser and Moore, 2014). 

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). 

Masking affects both senders and 

receivers of acoustic signals and can 

potentially have long-term chronic 

effects on marine mammals at the 

population level as well as at the 

individual level. Low-frequency 

ambient sound levels have increased by 

as much as 20 dB (more than three times 

in terms of SPL) in the world’s ocean 


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from pre-industrial periods, with most 

of the increase from distant commercial 

shipping (Hildebrand, 2009). All 

anthropogenic sound sources, but 

especially chronic and lower-frequency 

signals (e.g., from commercial vessel 

traffic), contribute to elevated ambient 

sound levels, thus intensifying masking. 

Richardson et al. (1995b) argued that 

the maximum radius of influence of an 

industrial noise (including broadband 

low-frequency sound transmission) on a 

marine mammal is the distance from the 

source to the point at which the noise 

can barely be heard. This range is 

determined by either the hearing 

sensitivity of the animal or the 

background noise level present. 

Industrial masking is most likely to 

affect some species’ ability to detect 

communication calls and natural 

sounds (i.e., surf noise, prey noise, etc.; 

Richardson et al., 1995). 

The echolocation calls of toothed 

whales are subject to masking by highfrequency sound. Human data indicate 

low-frequency sound can mask highfrequency sounds (i.e., upward 

masking). Studies on captive 

odontocetes by Au et al. (1974, 1985, 

1993) indicate that some species may 

use various processes to reduce masking 

effects (e.g., adjustments in echolocation 

call intensity or frequency as a function 

of background noise conditions). There 

is also evidence that the directional 

hearing abilities of odontocetes are 

useful in reducing masking at the highfrequencies these cetaceans use to 

echolocate, but not at the low-tomoderate frequencies they use to 

communicate (Zaitseva et al., 1980). A 

study by Nachtigall and Supin (2008) 

showed that false killer whales adjust 

their hearing to compensate for ambient 

sounds and the intensity of returning 

echolocation signals. Holt et al. (2009) 

measured killer whale call source levels 

and background noise levels in the one 

to 40 kHz band and reported that the 

whales increased their call source levels 

by one dB SPL for every one dB SPL 

increase in background noise level. 

Similarly, another study on St. 

Lawrence River belugas reported a 

similar rate of increase in vocalization 

activity in response to passing vessels 

(Scheifele et al., 2005). 

Parks et al. (2007) provided evidence 

of behavioral changes in the acoustic 

behaviors of the endangered North 

Atlantic right whale, and the South 

Atlantic southern right whale, and 

suggested that these were correlated to 

increased underwater noise levels. The 

study indicated that right whales might 

shift the frequency band of their calls to 

compensate for increased in-band 

background noise. The significance of 

their result is the indication of potential 

species-wide behavioral change in 

response to gradual, chronic increases 

in underwater ambient noise. Di Iorio 

and Clark (2010) showed that blue 

whale calling rates vary in association 

with seismic sparker survey activity, 

with whales calling more on days with 

survey than on days without surveys. 

They suggested that the whales called 

more during seismic survey periods as 

a way to compensate for the elevated 

noise conditions. 

Risch et al. (2012) documented 

reductions in humpback whale 

vocalizations in the Stellwagen Bank 

National Marine Sanctuary concurrent 

with transmissions of the Ocean 

Acoustic Waveguide Remote Sensing 

(OAWRS) low-frequency fish sensor 

system at distances of 200 km (124 mi) 

from the source. The recorded OAWRS 

produced a series of frequency 

modulated pulses and the signal 

received levels ranged from 88 to 110 

dB re: 1 mPa (Risch, et al., 2012). The 

authors hypothesized that individuals 

did not leave the area but instead ceased 

singing and noted that the duration and 

frequency range of the OAWRS signals 

(a novel sound to the whales) were 

similar to those of natural humpback 

whale song components used during 

mating (Risch et al., 2012). Thus, the 

novelty of the sound to humpback 

whales in the Navy’s Study Area 

(Navy’s Atlantic Fleet Study Area) 

provided a compelling contextual 

probability for the observed effects 

(Risch et al., 2012). However, the 

authors did not state or imply that these 

changes had long-term effects on 

individual animals or populations 

(Risch et al., 2012). 

Redundancy and context can also 

facilitate detection of weak signals. 

These phenomena may help marine 

mammals detect weak sounds in the 

presence of natural or manmade noise. 

Most masking studies in marine 

mammals present the test signal and the 

masking noise from the same direction. 

The dominant background noise may be 

highly directional if it comes from a 

particular anthropogenic source such as 

a ship or industrial site. Directional 

hearing may significantly reduce the 

masking effects of these sounds by 

improving the effective signal-to-noise 

ratio. 

The functional hearing ranges of 

mysticetes, odontocetes, and pinnipeds 

underwater all overlap the frequencies 

of the sonar sources used in the Navy’s 

low-frequency active sonar (LFAS)/midfrequency active sonar (MFAS)/highfrequency active sonar (HFAS) training 

and testing exercises. Additionally, 

almost all species’ vocal repertoires 

span across the frequencies of these 

sonar sources used by the Navy. The 

closer the characteristics of the masking 

signal to the signal of interest, the more 

likely masking is to occur. Although 

hull-mounted sonar accounts for a large 

portion of the area ensonified by Navy 

activities (because of the source strength 

and number of hours it is conducted), 

the pulse length and low duty cycle of 

the MFAS/HFAS signal makes it less 

likely that masking would occur as a 

result. 

Impaired Communication 

In addition to making it more difficult 

for animals to perceive acoustic cues in 

their environment, anthropogenic sound 

presents separate challenges for animals 

that are vocalizing. When they vocalize, 

animals are aware of environmental 

conditions that affect the ‘‘active space’’ 

of their vocalizations, which is the 

maximum area within which their 

vocalizations can be detected before it 

drops to the level of ambient noise 

(Brenowitz, 2004; Brumm et al., 2004; 

Lohr et al., 2003). Animals are also 

aware of environmental conditions that 

affect whether listeners can discriminate 

and recognize their vocalizations from 

other sounds, which is more important 

than simply detecting that a 

vocalization is occurring (Brenowitz, 

1982; Brumm et al., 2004; Dooling, 

2004, Marten and Marler, 1977; 

Patricelli et al., 2006). Most species that 

vocalize have evolved with an ability to 

make adjustments to their vocalizations 

to increase the signal-to-noise ratio, 

active space, and recognizability/ 

distinguishability of their vocalizations 

in the face of temporary changes in 

background noise (Brumm et al., 2004; 

Patricelli et al., 2006). Vocalizing 

animals can make adjustments to 

vocalization characteristics such as the 

frequency structure, amplitude, 

temporal structure, and temporal 

delivery. 

Many animals will combine several of 

these strategies to compensate for high 

levels of background noise. 

Anthropogenic sounds that reduce the 

signal-to-noise ratio of animal 

vocalizations, increase the masked 

auditory thresholds of animals listening 

for such vocalizations, or reduce the 

active space of an animal’s vocalizations 

impair communication between 

animals. Most animals that vocalize 

have evolved strategies to compensate 

for the effects of short-term or temporary 

increases in background or ambient 

noise on their songs or calls. Although 

the fitness consequences of these vocal 

adjustments are not directly known in 

all instances, like most other trade-offs 

animals must make, some of these 


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strategies probably come at a cost 

(Patricelli et al., 2006). Shifting songs 

and calls to higher frequencies may also 

impose energetic costs (Lambrechts, 

1996). For example in birds, vocalizing 

more loudly in noisy environments may 

have energetic costs that decrease the 

net benefits of vocal adjustment and 

alter a bird’s energy budget (Brumm, 

2004; Wood and Yezerinac, 2006). 

Stress Response 

Classic stress responses begin when 

an animal’s central nervous system 

perceives a potential threat to its 

homeostasis. That perception triggers 

stress responses regardless of whether a 

stimulus actually threatens the animal; 

the mere perception of a threat is 

sufficient to trigger a stress response 

(Moberg, 2000; Sapolsky et al., 2005; 

Seyle, 1950). Once an animal’s central 

nervous system perceives a threat, it 

mounts a biological response or defense 

that consists of a combination of the 

four general biological defense 

responses: behavioral responses, 

autonomic nervous system responses, 

neuroendocrine responses, or immune 

responses. 

According to Moberg (2000), in the 

case of many stressors, an animal’s first 

and sometimes most economical (in 

terms of biotic costs) response is 

behavioral avoidance of the potential 

stressor or avoidance of continued 

exposure to a stressor. An animal’s 

second line of defense to stressors 

involves the sympathetic part of the 

autonomic nervous system and the 

classical ‘‘fight or flight’’ response 

which includes the cardiovascular 

system, the gastrointestinal system, the 

exocrine glands, and the adrenal 

medulla to produce changes in heart 

rate, blood pressure, and gastrointestinal 

activity that humans commonly 

associate with ‘‘stress.’’ These responses 

have a relatively short duration and may 

or may not have significant long-term 

effect on an animal’s welfare. 

An animal’s third line of defense to 

stressors involves its neuroendocrine 

systems or sympathetic nervous 

systems; the system that has received 

the most study has been the 

hypothalmus-pituitary-adrenal system 

(also known as the HPA axis in 

mammals or the hypothalamuspituitary-interrenal axis in fish and 

some reptiles). Unlike stress responses 

associated with the autonomic nervous 

system, virtually all neuro-endocrine 

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 

(Moberg, 1987; Rivier and Rivest, 1991), 

altered metabolism (Elasser et al., 2000), 

reduced immune competence (Blecha, 

2000), and behavioral disturbance 

(Moberg, 1987; Blecha, 2000). Increases 

in the circulation of glucocorticosteroids 

(cortisol, corticosterone, and 

aldosterone in marine mammals; see 

Romano et al., 2004) have been equated 

with stress for many years. 

The primary distinction between 

stress (which is adaptive and does not 

normally place an animal at risk) and 

distress is the biotic 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 a risk to the animal’s welfare. 

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 biotic function, which impairs 

those functions that experience the 

diversion. For example, when a stress 

response diverts energy away from 

growth in young animals, those animals 

may experience stunted growth. When a 

stress response diverts energy from a 

fetus, an animal’s reproductive success 

and its fitness will suffer. In these cases, 

the animals will have entered a prepathological or pathological state which 

is called ‘‘distress’’ (Seyle, 1950) or 

‘‘allostatic loading’’ (McEwen and 

Wingfield, 2003). This pathological state 

will last until the animal replenishes its 

biotic reserves sufficient to restore 

normal function. Note that these 

examples involved a long-term (days or 

weeks) stress response exposure to 

stimuli. 

Relationships between these 

physiological mechanisms, animal 

behavior, and the costs of stress 

responses have also been documented 

fairly well through controlled 

experiments in terrestrial vertebrates; 

because this physiology exists in every 

vertebrate that has been studied, it is not 

surprising that stress responses and 

their costs have been documented in 

both laboratory and free-living animals 

(for examples see, Holberton et al., 

1996; Hood et al., 1998; Jessop et al., 

2003; Krausman et al., 2004; Lankford et 

al., 2005; Reneerkens et al., 2002; 

Thompson and Hamer, 2000). 

Information has also been collected 

on the physiological responses of 

marine mammals to exposure to 

anthropogenic sounds (Fair and Becker, 

2000; Romano et al., 2002; Wright et al., 

2008). Various efforts have been 

undertaken to investigate the impact 

from vessels (both whale-watching and 

general vessel traffic noise), and 

demonstrated impacts do occur (Bain, 

2002; Erbe, 2002; Noren et al., 2009; 

Williams et al., 2006, 2009, 2014a, 

2014b; Read et al., 2014; Rolland et al., 

2012; Pirotta et al., 2015). This body of 

research for the most part has 

investigated impacts associated with the 

presence of chronic stressors, which 

differ significantly from the proposed 

Navy training and testing activities in 

the HSTT Study Area. For example, in 

an analysis of energy costs to killer 

whales, Williams et al. (2009) suggested 

that whale-watching in Canada’s 

Johnstone Strait resulted in lost feeding 

opportunities due to vessel disturbance, 

which could carry higher costs than 

other measures of behavioral change 

might suggest. Ayres et al. (2012) 

recently reported on research in the 

Salish Sea (Washington state) involving 

the measurement of southern resident 

killer whale fecal hormones to assess 

two potential threats to the species 

recovery: Lack of prey (salmon) and 

impacts to behavior from vessel traffic. 

Ayres et al. (2012) suggested that the 

lack of prey overshadowed any 

population-level physiological impacts 

on southern resident killer whales from 

vessel traffic. 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. In a 

conceptual model developed by the 

Population Consequences of Acoustic 

Disturbance (PCAD) working group, 

serum hormones were identified as 

possible indicators of behavioral effects 

that are translated into altered rates of 

reproduction and mortality (NRC, 2005). 

The Office of Naval Research hosted a 

workshop (Effects of Stress on Marine 

Mammals Exposed to Sound) in 2009 

that focused on this very topic (ONR, 

2009). Ultimately, the PCAD working 

group issued a report (Cochrem, 2014) 

that summarized information compiled 

from 239 papers or book chapters 

relating to stress in marine mammals 

and concluded that stress responses can 

last from minutes to hours and, while 

we typically focus on adverse stress 

responses, stress response is part of a 

natural process to help animals adjust to 

changes in their environment and can 

also be either neutral or beneficial. 

Despite the lack of robust information 

on stress responses for marine mammals 

exposed to anthropogenic sounds, 

studies of other marine animals and 

terrestrial animals would also lead us to 

expect some marine mammals to 

experience physiological stress 

responses and, perhaps, physiological 

responses that would be classified as 


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‘‘distress’’ upon exposure to high 

frequency, mid-frequency, and lowfrequency sounds. For example, Jansen 

(1998) reported on the relationship 

between acoustic exposures and 

physiological responses that are 

indicative of stress responses in humans 

(e.g., elevated respiration and increased 

heart rates). Jones (1998) reported on 

reductions in human performance when 

faced with acute, repetitive exposures to 

acoustic disturbance. Trimper et al. 

(1998) reported on the physiological 

stress responses of osprey to low-level 

aircraft noise while Krausman et al. 

(2004) reported on the auditory and 

physiological stress responses of 

endangered Sonoran pronghorn to 

military overflights. Smith et al. (2004a, 

2004b) identified noise-induced 

physiological transient stress responses 

in hearing-specialist fish (i.e., goldfish) 

that accompanied short- and long-term 

hearing losses. Welch and Welch (1970) 

reported physiological and behavioral 

stress responses that accompanied 

damage to the inner ears of fish and 

several mammals. 

Behavioral Response/Disturbance 

Behavioral responses to sound are 

highly variable and context-specific. 

Many different variables can influence 

an animal’s perception of and response 

to (nature and magnitude) an acoustic 

event. An animal’s prior experience 

with a sound or sound source affects 

whether it is less likely (habituation) or 

more likely (sensitization) to respond to 

certain sounds in the future (animals 

can also be innately pre-disposed to 

respond to certain sounds in certain 

ways) (Southall et al., 2007). Related to 

the sound itself, the perceived nearness 

of the sound, bearing of the sound 

(approaching vs. retreating), similarity 

of a sound to biologically relevant 

sounds in the animal’s environment 

(i.e., calls of predators, prey, or 

conspecifics), and familiarity of the 

sound may affect the way an animal 

responds to the sound (Southall et al., 

2007, DeRuiter et al., 2013). Individuals 

(of different age, gender, reproductive 

status, etc.) among most populations 

will have variable hearing capabilities, 

and differing behavioral sensitivities to 

sounds that will be affected by prior 

conditioning, experience, and current 

activities of those individuals. Often, 

specific acoustic features of the sound 

and contextual variables (i.e., proximity, 

duration, or recurrence of the sound or 

the current behavior that the marine 

mammal is engaged in or its prior 

experience), as well as entirely separate 

factors such as the physical presence of 

a nearby vessel, may be more relevant 

to the animal’s response than the 

received level alone. For example, 

Goldbogen et al. (2013) demonstrated 

that individual behavioral state was 

critically important in determining 

response of blue whales to sonar, noting 

that some individuals engaged in deep 

(>50 m) feeding behavior had greater 

dive responses than those in shallow 

feeding or non-feeding conditions. Some 

blue whales in the Goldbogen et al. 

(2013) study that were engaged in 

shallow feeding behavior demonstrated 

no clear changes in diving or movement 

even when RLs were high (∼160 dB re 

1mPa) for exposures to 3–4 kHz sonar 

signals, while others showed a clear 

response at exposures at lower RLs of 

sonar and pseudorandom noise. 

Studies by DeRuiter et al. (2012) 

indicate that variability of responses to 

acoustic stimuli depends not only on 

the species receiving the sound and the 

sound source, but also on the social, 

behavioral, or environmental contexts of 

exposure. Another study by DeRuiter et 

al. (2013) examined behavioral 

responses of Cuvier’s beaked whales to 

MF sonar and found that whales 

responded strongly at low received 

levels (RL of 89–127 dB re 1mPa) by 

ceasing normal fluking and 

echolocation, swimming rapidly away, 

and extending both dive duration and 

subsequent non-foraging intervals when 

the sound source was 3.4–9.5 km away. 

Importantly, this study also showed that 

whales exposed to a similar range of RLs 

(78–106 dB re 1mPa) from distant sonar 

exercises (118 km away) did not elicit 

such responses, suggesting that context 

may moderate reactions. 

Ellison et al. (2012) outlined an 

approach to assessing the effects of 

sound on marine mammals that 

incorporates contextual-based factors. 

The authors recommend considering not 

just the received level of sound, but also 

the activity the animal is engaged in at 

the time the sound is received, the 

nature and novelty of the sound (i.e., is 

this a new sound from the animal’s 

perspective), and the distance between 

the sound source and the animal. They 

submit that this ‘‘exposure context,’’ as 

described, greatly influences the type of 

behavioral response exhibited by the 

animal. This sort of contextual 

information is challenging to predict 

with accuracy for ongoing activities that 

occur over large spatial and temporal 

expanses. However, distance is one 

contextual factor for which data exist to 

quantitatively inform a take estimate, 

and the new method for predicting 

Level B harassment proposed in this 

notice does consider distance to the 

source. Other factors are often 

considered qualitatively in the analysis 

of the likely consequences of sound 

exposure, where supporting information 

is available. 

Friedlaender et al. (2016) provided 

the first integration of direct measures of 

prey distribution and density variables 

incorporated into across-individual 

analyses of behavior responses of blue 

whales to sonar, and demonstrated a 

five-fold increase in the ability to 

quantify variability in blue whale diving 

behavior. These results illustrate that 

responses evaluated without such 

measurements for foraging animals may 

be misleading, which again illustrates 

the context-dependent nature of the 

probability of response. 

Exposure of marine mammals to 

sound sources can result in, but is not 

limited to, no response or any of the 

following observable response: 

Increased alertness; orientation or 

attraction to a sound source; vocal 

modifications; cessation of feeding; 

cessation of social interaction; alteration 

of movement or diving behavior; habitat 

abandonment (temporary or permanent); 

and, in severe cases, panic, flight, 

stampede, or stranding, potentially 

resulting in death (Southall et al., 2007). 

A review of marine mammal responses 

to anthropogenic sound was first 

conducted by Richardson (1995). More 

recent reviews (Nowacek et al., 2007; 

DeRuiter et al., 2012 and 2013; Ellison 

et al., 2012) address studies conducted 

since 1995 and focused on observations 

where the received sound level of the 

exposed marine mammal(s) was known 

or could be estimated. Southall et al. 

(2016) states that results demonstrate 

that some individuals of different 

species display clear yet varied 

responses, some of which have negative 

implications, while others appear to 

tolerate high levels, and that responses 

may not be fully predicable with simple 

acoustic exposure metrics (e.g., received 

sound level). Rather, the authors state 

that differences among species and 

individuals along with contextual 

aspects of exposure (e.g., behavioral 

state) appear to affect response 

probability. The following sub-sections 

provide examples of behavioral 

responses that provide an idea of the 

variability in behavioral responses that 

would be expected given the differential 

sensitivities of marine mammal species 

to sound and the wide range of potential 

acoustic sources to which a marine 

mammal may be exposed. Predictions 

about of the types of behavioral 

responses that could occur for a given 

sound exposure should be determined 

from the literature that is available for 

each species, or extrapolated from 

closely related species when no 

information exists, along with 

contextual factors. 


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Flight Response 

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. 

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). Flight 

responses have been speculated as being 

a component of marine mammal 

strandings associated with sonar 

activities (Evans and England, 2001). If 

marine mammals respond to Navy 

vessels that are transmitting active sonar 

in the same way that they might 

respond to a predator, their probability 

of flight responses should increase 

when they perceive that Navy vessels 

are approaching them directly, because 

a direct approach may convey detection 

and intent to capture (Burger and 

Gochfeld, 1981, 1990; Cooper, 1997, 

1998). There are limited data on flight 

response for marine mammals; however, 

there are examples of this response in 

terrestrial species. For instance, the 

probability of flight responses in Dall’s 

sheep Ovis dalli dalli (Frid, 2001), 

hauled-out ringed seals Phoca hispida 

(Born et al., 1999), Pacific brant (Branta 

bernicl nigricans), and Canada geese (B. 

canadensis) increased as a helicopter or 

fixed-wing aircraft more directly 

approached groups of these animals 

(Ward et al., 1999). Bald eagles 

(Haliaeetus leucocephalus) perched on 

trees alongside a river were also more 

likely to flee from a paddle raft when 

their perches were closer to the river or 

were closer to the ground (Steidl and 

Anthony, 1996). 

Response to Predator 

Evidence suggests that at least some 

marine mammals have the ability to 

acoustically identify potential predators. 

For example, harbor seals that reside in 

the coastal waters off British Columbia 

are frequently targeted by certain groups 

of killer whales, but not others. The 

seals discriminate between the calls of 

threatening and non-threatening killer 

whales (Deecke et al., 2002), a capability 

that should increase survivorship while 

reducing the energy required for 

attending to and responding to all killer 

whale calls. The occurrence of masking 

or hearing impairment provides a means 

by which marine mammals may be 

prevented from responding to the 

acoustic cues produced by their 

predators. Whether or not this is a 

possibility depends on the duration of 

the masking/hearing impairment and 

the likelihood of encountering a 

predator during the time that predator 

cues are impeded. 

Alteration of Diving or Movement 

Changes in dive behavior can vary 

widely. They 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. 

Variations in dive behavior may reflect 

interruptions in biologically significant 

activities (e.g., foraging) or they may be 

of little biological significance. 

Variations in dive behavior may also 

expose an animal to potentially harmful 

conditions (e.g., increasing the chance 

of ship-strike) or may serve as an 

avoidance response that enhances 

survivorship. The impact of a variation 

in diving 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. 

Nowacek et al. (2004) reported 

disruptions of dive behaviors in foraging 

North Atlantic right whales when 

exposed to an alerting stimulus, an 

action, they noted, that could lead to an 

increased likelihood of ship strike. 

However, the whales did not respond to 

playbacks of either right whale social 

sounds or vessel noise, highlighting the 

importance of the sound characteristics 

in producing a behavioral reaction. 

Conversely, Indo-Pacific humpback 

dolphins have been observed to dive for 

longer periods of time in areas where 

vessels were present and/or 

approaching (Ng and Leung, 2003). In 

both of these studies, the influence of 

the sound exposure cannot be 

decoupled from the physical presence of 

a surface vessel, thus complicating 

interpretations of the relative 

contribution of each stimulus to the 

response. Indeed, the presence of 

surface vessels, their approach, and 

speed of approach, seemed to be 

significant factors in the response of the 

Indo-Pacific humpback dolphins (Ng 

and Leung, 2003). Low frequency 

signals of the Acoustic Thermometry of 

Ocean Climate (ATOC) sound source 

were not found to affect dive times of 

humpback whales in Hawaiian waters 

(Frankel and Clark, 2000) or to overtly 

affect elephant seal dives (Costa et al., 

2003). They did, however, produce 

subtle effects that varied in direction 

and degree among the individual seals, 

illustrating the equivocal nature of 

behavioral effects and consequent 

difficulty in defining and predicting 

them. Lastly, as noted previously, 

DeRuiter et al. (2013) noted that 

distance from a sound source may 

moderate marine mammal reactions in 

their study of Cuvier’s beaked whales 

showing the whales swimming rapidly 

and silently away when a sonar signal 

was 3.4–9.5 km away while showing no 

such reaction to the same signal when 

the signal was 118 km away even 

though the RLs were similar. 

Foraging 

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. Noise from seismic surveys 

was not found to impact the feeding 

behavior in western grey whales off the 

coast of Russia (Yazvenko et al., 2007). 

Visual tracking, passive acoustic 

monitoring, and movement recording 

tags were used to quantify sperm whale 

behavior prior to, during, and following 

exposure to air gun arrays at received 

levels in the range 140–160 dB at 

distances of 7–13 km, following a phasein of sound intensity and full array 

exposures at 1–13 km (Madsen et al., 

2006a; Miller et al., 2009). Sperm 

whales did not exhibit horizontal 

avoidance behavior at the surface. 

However, foraging behavior may have 

been affected. The sperm whales 

exhibited 19 percent less vocal (buzz) 

rate during full exposure relative to post 

exposure, and the whale that was 

approached most closely had an 

extended resting period and did not 

resume foraging until the air guns had 

ceased firing. The remaining whales 

continued to execute foraging dives 

throughout exposure; however, 

swimming movements during foraging 

dives were six percent lower during 

exposure than control periods (Miller et 

al., 2009). These data raise concerns that 

air gun surveys may impact foraging 

behavior in sperm whales, although 

more data are required to understand 

whether the differences were due to 

exposure or natural variation in sperm 

whale behavior (Miller et al., 2009). 

Balaenopterid whales exposed to 

moderate low-frequency signals similar 

to the ATOC sound source 

demonstrated no variation in foraging 

activity (Croll et al., 2001), whereas five 

out of six North Atlantic right whales 

exposed to an acoustic alarm 

interrupted their foraging dives 

(Nowacek et al., 2004). Although the 

received SPLs were similar in the latter 

two studies, the frequency, duration, 

and temporal pattern of signal 

presentation were different. These 

factors, as well as differences in species 

sensitivity, are likely contributing 

factors to the differential response. Blue 

whales exposed to mid-frequency sonar 

in the Southern California Bight were 


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less likely to produce low frequency 

calls usually associated with feeding 

behavior (Melco ́n et al., 2012). However, 

Melco ́n et al. (2012) were unable to 

determine if suppression of low 

frequency calls reflected a change in 

their feeding performance or 

abandonment of foraging behavior and 

indicated that implications of the 

documented responses are unknown. 

Further, it is not known whether the 

lower rates of calling actually indicated 

a reduction in feeding behavior or social 

contact since the study used data from 

remotely deployed, passive acoustic 

monitoring buoys. In contrast, blue 

whales increased their likelihood of 

calling when ship noise was present, 

and decreased their likelihood of calling 

in the presence of explosive noise, 

although this result was not statistically 

significant (Melco ́n et al., 2012). 

Additionally, the likelihood of an 

animal calling decreased with the 

increased received level of midfrequency sonar, beginning at a SPL of 

approximately 110–120 dB re 1 mPa 

(Melco ́n et al., 2012). Results from the 

2010–2011 field season of an ongoing 

behavioral response study in Southern 

California waters indicated that, in some 

cases and at low received levels, tagged 

blue whales responded to midfrequency sonar but that those responses 

were mild and there was a quick return 

to their baseline activity (Southall et al., 

2011; Southall et al., 2012b). 

Information on or estimates of the 

energetic requirements of the 

individuals and the relationship 

between prey availability, foraging effort 

and success, and the life history stage of 

the animal will help better inform a 

determination of whether foraging 

disruptions incur fitness consequences. 

Goldbogen et al. (2013) monitored 

behavioral responses of tagged blue 

whales located in feeding areas when 

exposed to simulated MFA sonar. 

Responses varied depending on 

behavioral context, with some deep 

feeding whales being more significantly 

affected (i.e., generalized avoidance; 

cessation of feeding; increased 

swimming speeds; or directed travel 

away from the source) compared to 

surface feeding individuals that 

typically showed no change in behavior. 

The authors indicate that disruption of 

feeding and displacement could impact 

individual fitness and health. However, 

for this to be true, we would have to 

assume that an individual whale could 

not compensate for this lost feeding 

opportunity by either immediately 

feeding at another location, by feeding 

shortly after cessation of acoustic 

exposure, or by feeding at a later time. 

There is no indication this is the case, 

particularly since unconsumed prey 

would likely still be available in the 

environment in most cases following the 

cessation of acoustic exposure. 

Breathing 

Variations in respiration naturally 

vary with different behaviors and 

variations in respiration 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. 

Mean exhalation rates of gray whales at 

rest and while diving were found to be 

unaffected by seismic surveys 

conducted adjacent to the whale feeding 

grounds (Gailey et al., 2007). Studies 

with captive harbor porpoises showed 

increased respiration rates upon 

introduction of acoustic alarms 

(Kastelein et al., 2001; Kastelein et al., 

2006a) and emissions for underwater 

data transmission (Kastelein et al., 

2005). However, exposure of the same 

acoustic alarm to a striped dolphin 

under the same conditions did not elicit 

a response (Kastelein et al., 2006a), 

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. 

Social Relationships 

Social interactions between mammals 

can be affected by noise via the 

disruption of communication signals or 

by the displacement of individuals. 

Disruption of social relationships 

therefore depends on the disruption of 

other behaviors (e.g., caused avoidance, 

masking, etc.). Sperm whales responded 

to military sonar, apparently from a 

submarine, by dispersing from social 

aggregations, moving away from the 

sound source, remaining relatively 

silent, and becoming difficult to 

approach (Watkins et al., 1985). In 

contrast, sperm whales in the 

Mediterranean that were exposed to 

submarine sonar continued calling (J. 

Gordon pers. comm. cited in Richardson 

et al., 1995). Long-finned pilot whales 

exposed to three types of disturbance— 

playbacks of killer whale sounds, naval 

sonar exposure, and tagging all resulted 

in increased group sizes (Visser et al., 

2016). In response to sonar, pilot whales 

also spent more time at the surface with 

other members of the group (Visser et 

al., 2016). However, social disruptions 

must be considered in context of the 

relationships that are affected. While 

some disruptions may not have 

deleterious effects, others, such as longterm or repeated disruptions of mother/ 

calf pairs or interruption of mating 

behaviors, have the potential to affect 

the growth and survival or reproductive 

effort/success of individuals. 

Vocalizations (Also See Masking 

Section) 

Vocal changes in response to 

anthropogenic noise can occur across 

the repertoire of sound production 

modes used by marine mammals, such 

as whistling, echolocation click 

production, calling, and singing. 

Changes may result in response to a 

need to compete with an increase in 

background noise or may reflect an 

increased vigilance or startle response. 

For example, in the presence of lowfrequency active sonar, humpback 

whales have been observed to increase 

the length of their ‘‘songs’’ (Miller et al., 

2000; Fristrup et al., 2003), possibly due 

to the overlap in frequencies between 

the whale song and the low-frequency 

active sonar. A similar compensatory 

effect for the presence of low-frequency 

vessel noise has been suggested for right 

whales; right whales 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; 

Roland et al., 2012). Killer whales off 

the northwestern coast of the United 

States have been observed to increase 

the duration of primary calls once a 

threshold in observing vessel density 

(e.g., whale watching) was reached, 

which has been suggested as a response 

to increased masking noise produced by 

the vessels (Foote et al., 2004; NOAA, 

2014b). In contrast, both sperm and 

pilot whales potentially ceased sound 

production during the Heard Island 

feasibility test (Bowles et al., 1994), 

although it cannot be absolutely 

determined whether the inability to 

acoustically detect the animals was due 

to the cessation of sound production or 

the displacement of animals from the 

area. 

Cerchio et al. (2014) used passive 

acoustic monitoring to document the 

presence of singing humpback whales 

off the coast of northern Angola and to 

opportunistically test for the effect of 

seismic survey activity on the number of 

singing whales. Two recording units 

were deployed between March and 

December 2008 in the offshore 

environment; numbers of singers were 

counted every hour. Generalized 

Additive Mixed Models were used to 

assess the effect of survey day 

(seasonality), hour (diel variation), 

moon phase, and received levels of 


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noise (measured from a single pulse 

during each ten-minute sampled period) 

on singer number. The number of 

singers significantly decreased with 

increasing received level of noise, 

suggesting that humpback whale 

communication was disrupted to some 

extent by the survey activity. 

Castellote et al. (2012) reported 

acoustic and behavioral changes by fin 

whales in response to shipping and air 

gun noise. Acoustic features of fin 

whale song notes recorded in the 

Mediterranean Sea and northeast 

Atlantic Ocean were compared for areas 

with different shipping noise levels and 

traffic intensities and during an air gun 

survey. During the first 72 hrs of the 

survey, a steady decrease in song 

received levels and bearings to singers 

indicated that whales moved away from 

the acoustic source and out of a Navy 

Study Area. This displacement persisted 

for a time period well beyond the 10- 

day duration of air gun activity, 

providing evidence that fin whales may 

avoid an area for an extended period in 

the presence of increased noise. The 

authors hypothesize tha fin whale 

acoustic communication is modified to 

compensate for increased background 

noise and that a sensitization process 

may play a role in the observed 

temporary displacement. 

Seismic pulses at average received 

levels of 131 dB re 1 micropascal 

squared per second (mPa2-s) caused blue 

whales to increase call production (Di 

Iorio and Clark, 2010). In contrast, 

McDonald et al. (1995) tracked a blue 

whale with seafloor seismometers and 

reported that it stopped vocalizing and 

changed its travel direction at a range of 

10 km from the seismic vessel 

(estimated received level 143 dB re 1 

mPa peak-to-peak). Blackwell et al. 

(2013) found that bowhead whale call 

rates dropped significantly at onset of 

air gun use at sites with a median 

distance of 41–45 km from the survey. 

Blackwell et al. (2015) expanded this 

analysis to show that whales actually 

increased calling rates as soon as air gun 

signals were detectable before 

ultimately decreasing calling rates at 

higher received levels (i.e., 10-minute 

cSEL of ∼127 dB). Overall, these results 

suggest that bowhead whales may adjust 

their vocal output in an effort to 

compensate for noise before ceasing 

vocalization effort and ultimately 

deflecting from the acoustic source 

(Blackwell et al., 2013, 2015). Captive 

bottlenose dolphins sometimes 

vocalized after an exposure to impulse 

sound from a seismic water gun 

(Finneran et al., 2010a). These studies 

demonstrate that even low levels of 

noise received far from the noise source 

can induce behavioral responses. 

Avoidance 

Avoidance is the displacement of an 

individual from an area as a result of the 

presence of a sound. Richardson et al. 

(1995) noted that avoidance reactions 

are the most obvious manifestations of 

disturbance in marine mammals. 

Avoidance is qualitatively different 

from the flight response, but also differs 

in the magnitude of the response (i.e., 

directed movement, rate of travel, etc.). 

Oftentimes avoidance is temporary, and 

animals return to the area once the noise 

has ceased. However, longer term 

displacement is possible and can lead to 

changes in abundance or distribution 

patterns of the species in the affected 

region if they do not become acclimated 

to the presence of the sound (Blackwell 

et al., 2004; Bejder et al., 2006; 

Teilmann et al., 2006). Acute avoidance 

responses have been observed in captive 

porpoises and pinnipeds exposed to a 

number of different sound sources 

(Kastelein et al., 2001; Finneran et al., 

2003; Kastelein et al., 2006a; Kastelein 

et al., 2006b). Short-term avoidance of 

seismic surveys, low frequency 

emissions, and acoustic deterrents have 

also been noted in wild populations of 

odontocetes (Bowles et al., 1994; Goold, 

1996; 1998; Stone et al., 2000; Morton 

and Symonds, 2002) and to some extent 

in mysticetes (Gailey et al., 2007), while 

longer term or repetitive/chronic 

displacement for some dolphin groups 

and for manatees has been suggested to 

be due to the presence of chronic vessel 

noise (Haviland-Howell et al., 2007; 

Miksis-Olds et al., 2007). Gray whales 

have been reported deflecting from 

customary migratory paths in order to 

avoid noise from air gun surveys 

(Malme et al., 1984). Humpback whales 

showed avoidance behavior in the 

presence of an active air gun array 

during observational studies and 

controlled exposure experiments in 

western Australia (McCauley et al., 

2000a). 

In 1998, the Navy conducted a Low 

Frequency Sonar Scientific Research 

Program (LFS SRP) specifically to study 

behavioral responses of several species 

of marine mammals to exposure to LF 

sound, including one phase that focused 

on the behavior of gray whales to low 

frequency sound signals. The objective 

of this phase of the LFS SRP was to 

determine whether migrating gray 

whales respond more strongly to 

received levels, sound gradient, or 

distance from the source, and to 

compare whale avoidance responses to 

an LF source in the center of the 

migration corridor versus in the offshore 

portion of the migration corridor. A 

single source was used to broadcast LFA 

sonar sounds at received levels of 170– 

178 dB re 1mPa. The Navy reported that 

the whales showed some avoidance 

responses when the source was moored 

one mile (1.8 km) offshore, and located 

within in the migration path, but the 

whales returned to their migration path 

when they were a few kilometers 

beyond the source. When the source 

was moored two miles (3.7 km) offshore, 

responses were much less even when 

the source level was increased to 

achieve the same RLs in the middle of 

the migration corridor as whales 

received when the source was located 

within the migration corridor (Clark et 

al., 1999). In addition, the researchers 

noted that the offshore whales did not 

seem to avoid the louder offshore 

source. 

Also during the LFS SRP, researchers 

sighted numerous odontocete and 

pinniped species in the vicinity of the 

sound exposure tests with LFA sonar. 

The MF and HF hearing specialists 

present in California and Hawaii 

showed no immediately obvious 

responses or changes in sighting rates as 

a function of source conditions. 

Consequently, the researchers 

concluded that none of these species 

had any obvious behavioral reaction to 

LFA sonar signals at received levels 

similar to those that produced only 

minor short-term behavioral responses 

in the baleen whales (i.e., LF hearing 

specialists). Thus, for odontocetes, the 

chances of injury and/or significant 

behavioral responses to LFA sonar 

would be low given the MF/HF 

specialists’ observed lack of response to 

LFA sounds during the LFS SRP and 

due to the MF/HF frequencies to which 

these animals are adapted to hear (Clark 

and Southall, 2009). 

Maybaum (1993) conducted sound 

playback experiments to assess the 

effects of MFAS on humpback whales in 

Hawaiian waters. Specifically, she 

exposed focal pods to sounds of a 3.3- 

kHz sonar pulse, a sonar frequency 

sweep from 3.1 to 3.6 kHz, and a control 

(blank) tape while monitoring behavior, 

movement, and underwater 

vocalizations. The two types of sonar 

signals differed in their effects on the 

humpback whales, but both resulted in 

avoidance behavior. The whales 

responded to the pulse by increasing 

their distance from the sound source 

and responded to the frequency sweep 

by increasing their swimming speeds 

and track linearity. In the Caribbean, 

sperm whales avoided exposure to midfrequency submarine sonar pulses, in 

the range of 1000 Hz to 10,000 Hz (IWC, 

2005). 


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Kvadsheim et al. (2007) conducted a 

controlled exposure experiment in 

which killer whales fitted with D-tags 

were exposed to mid-frequency active 

sonar (Source A: A 1.0 second upsweep 

209 dB @1–2 kHz every 10 seconds for 

10 minutes; Source B: With a 1.0 second 

upsweep 197 dB @6–7 kHz every 10 

seconds for 10 minutes). When exposed 

to Source A, a tagged whale and the 

group it was traveling with did not 

appear to avoid the source. When 

exposed to Source B, the tagged whales 

along with other whales that had been 

carousel feeding, where killer whales 

cooperatively herd fish schools into a 

tight ball towards the surface and feed 

on the fish which have been stunned by 

tailslaps and subsurface feeding (Simila, 

1997), ceased feeding during the 

approach of the sonar and moved 

rapidly away from the source. When 

exposed to Source B, Kvadsheim et al. 

(2007) reported that a tagged killer 

whale seemed to try to avoid further 

exposure to the sound field by the 

following behaviors: Immediately 

swimming away (horizontally) from the 

source of the sound; engaging in a series 

of erratic and frequently deep dives that 

seemed to take it below the sound field; 

or swimming away while engaged in a 

series of erratic and frequently deep 

dives. Although the sample sizes in this 

study are too small to support statistical 

analysis, the behavioral responses of the 

killer whales were consistent with the 

results of other studies. 

Southall et al. (2007) reviewed the 

available literature on marine mammal 

hearing and physiological and 

behavioral responses to human-made 

sound with the goal of proposing 

exposure criteria for certain effects. This 

peer-reviewed compilation of literature 

is very valuable, though Southall et al. 

(2007) note that not all data are equal, 

some have poor statistical power, 

insufficient controls, and/or limited 

information on received levels, 

background noise, and other potentially 

important contextual variables. Such 

data were reviewed and sometimes used 

for qualitative illustration, but no 

quantitative criteria were recommended 

for behavioral responses. All of the 

studies considered, however, contain an 

estimate of the received sound level 

when the animal exhibited the indicated 

response. 

In the Southall et al. (2007) 

publication, for the purposes of 

analyzing responses of marine mammals 

to anthropogenic sound and developing 

criteria, the authors differentiate 

between single pulse sounds, multiple 

pulse sounds, and non-pulse sounds. 

LFAS/MFAS/HFAS are considered nonpulse sounds. Southall et al. (2007) 

summarize the studies associated with 

low-frequency, mid-frequency, and 

high-frequency cetacean and pinniped 

responses to non-pulse sounds, based 

strictly on received level, in Appendix 

C of their article (included in this 

preamble by reference and summarized 

in the following paragraphs below). 

The studies that address responses of 

low-frequency cetaceans to non-pulse 

sounds include data gathered in the 

field and related to several types of 

sound sources (of varying similarity to 

MFAS/HFAS) including: Vessel noise, 

drilling and machinery playback, lowfrequency M-sequences (sine wave with 

multiple phase reversals) playback, 

tactical low-frequency active sonar 

playback, drill ships, Acoustic 

Thermometry of Ocean Climate (ATOC) 

source, and non-pulse playbacks. These 

studies generally indicate no (or very 

limited) responses to received levels in 

the 90 to 120 dB re: 1 mPa range and an 

increasing likelihood of avoidance and 

other behavioral effects in the 120 to 

160 dB re: 1 mPa range. As mentioned 

earlier, though, contextual variables 

play a very important role in the 

reported responses and the severity of 

effects are not linear when compared to 

received level. Also, few of the 

laboratory or field datasets had common 

conditions, behavioral contexts or 

sound sources, so it is not surprising 

that responses differ. 

The studies that address responses of 

mid-frequency cetaceans to non-pulse 

sounds include data gathered both in 

the field and the laboratory and related 

to several different sound sources (of 

varying similarity to MFAS/HFAS) 

including: Pingers, drilling playbacks, 

ship and ice-breaking noise, vessel 

noise, Acoustic Harassment Devices 

(AHDs), Acoustic Deterrent Devices 

(ADDs), MFAS, and non-pulse bands 

and tones. Southall et al. (2007) were 

unable to come to a clear conclusion 

regarding the results of these studies. In 

some cases, animals in the field showed 

significant responses to received levels 

between 90 and 120 dB re: 1 mPa, while 

in other cases these responses were not 

seen in the 120 to 150 dB re: 1 mPa 

range. The disparity in results was 

likely due to contextual variation and 

the differences between the results in 

the field and laboratory data (animals 

typically responded at lower levels in 

the field). 

The studies that address responses of 

high-frequency cetaceans to non-pulse 

sounds include data gathered both in 

the field and the laboratory and related 

to several different sound sources (of 

varying similarity to MFAS/HFAS) 

including: Pingers, AHDs, and various 

laboratory non-pulse sounds. All of 

these data were collected from harbor 

porpoises. Southall et al. (2007) 

concluded that the existing data 

indicate that harbor porpoises are likely 

sensitive to a wide range of 

anthropogenic sounds at low received 

levels (∼90 to 120 dB re: 1 mPa), at least 

for initial exposures. All recorded 

exposures above 140 dB re: 1 mPa 

induced profound and sustained 

avoidance behavior in wild harbor 

porpoises (Southall et al., 2007). Rapid 

habituation was noted in some but not 

all studies. There are no data to indicate 

whether other high frequency cetaceans 

are as sensitive to anthropogenic sound 

as harbor porpoises. 

The studies that address the responses 

of pinnipeds in water to non-impulsive 

sounds include data gathered both in 

the field and the laboratory and related 

to several different sound sources 

including: AHDs, ATOC, various nonpulse sounds used in underwater data 

communication, underwater drilling, 

and construction noise. Few studies 

exist with enough information to 

include them in the analysis. The 

limited data suggested that exposures to 

non-pulse sounds between 90 and 140 

dB re: 1 mPa generally do not result in 

strong behavioral responses in 

pinnipeds in water, but no data exist at 

higher received levels. 

In 2007, the first in a series of 

behavioral response studies (BRS) on 

deep diving odontocetes conducted by 

NMFS, Navy, and other scientists 

showed one Blainville’s beaked whale 

responding to an MFAS playback. Tyack 

et al. (2011) indicates that the playback 

began when the tagged beaked whale 

was vocalizing at depth (at the deepest 

part of a typical feeding dive), following 

a previous control with no sound 

exposure. The whale appeared to stop 

clicking significantly earlier than usual, 

when exposed to MF signals in the 130– 

140 dB (rms) received level range. After 

a few more minutes of the playback, 

when the received level reached a 

maximum of 140–150 dB, the whale 

ascended on the slow side of normal 

ascent rates with a longer than normal 

ascent, at which point the exposure was 

terminated. The results are from a single 

experiment and a greater sample size is 

needed before robust and definitive 

conclusions can be drawn. Tyack et al. 

(2011) also indicates that Blainville’s 

beaked whales appear to be sensitive to 

noise at levels well below expected TTS 

(∼160 dB re1mPa). This sensitivity was 

manifested by an adaptive movement 

away from a sound source. This 

response was observed irrespective of 

whether the signal transmitted was 

within the band width of MFAS, which 

suggests that beaked whales may not 


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respond to the specific sound 

signatures. Instead, they may be 

sensitive to any pulsed sound from a 

point source in this frequency range of 

the MF active sonar transmission. The 

response to such stimuli appears to 

involve the beaked whale increasing the 

distance between it and the sound 

source. Overall the results from the 

2007–2008 study conducted showed a 

change in diving behavior of the 

Blainville’s beaked whale to playback of 

MFAS and predator sounds (Boyd et al., 

2008; Southall et al., 2009; Tyack et al., 

2011). 

Stimpert et al. (2014) tagged a Baird’s 

beaked whale, which was subsequently 

exposed to simulated MFAS. Received 

levels of sonar on the tag increased to 

a maximum of 138 dB re 1mPa, which 

occurred during the first exposure dive. 

Some sonar received levels could not be 

measured due to flow noise and surface 

noise on the tag. 

Reaction to mid-frequency sounds 

included premature cessation of 

clicking and termination of a foraging 

dive, and a slower ascent rate to the 

surface. Results from a similar 

behavioral response study in southern 

California waters have been presented 

for the 2010–2011 field season (Southall 

et al., 2011; DeRuiter et al., 2013b). 

DeRuiter et al. (2013b) presented results 

from two Cuvier’s beaked whales that 

were tagged and exposed to simulated 

MFAS during the 2010 and 2011 field 

seasons of the southern California 

behavioral response study. The 2011 

whale was also incidentally exposed to 

MFAS from a distant naval exercise. 

Received levels from the MFAS signals 

from the controlled and incidental 

exposures were calculated as 84–144 

and 78–106 dB re 1 mPa rms, 

respectively. Both whales showed 

responses to the controlled exposures, 

ranging from initial orientation changes 

to avoidance responses characterized by 

energetic fluking and swimming away 

from the source. However, the authors 

did not detect similar responses to 

incidental exposure to distant naval 

sonar exercises at comparable received 

levels, indicating that context of the 

exposures (e.g., source proximity, 

controlled source ramp-up) may have 

been a significant factor. Specifically, 

this result suggests that caution is 

needed when using marine mammal 

response data collected from smaller, 

nearer sound sources to predict at what 

received levels animals may respond to 

larger sound sources that are 

significantly farther away—as the 

distance of the source appears to be an 

important contextual variable and 

animals may be less responsive to 

sources at notably greater distances. 

Cuvier’s beaked whale responses 

suggested particular sensitivity to sound 

exposure as consistent with results for 

Blainville’s beaked whale. Similarly, 

beaked whales exposed to sonar during 

British training exercises stopped 

foraging (DSTL, 2007), and preliminary 

results of controlled playback of sonar 

may indicate feeding/foraging 

disruption of killer whales and sperm 

whales (Miller et al., 2011). 

In the 2007–2008 Bahamas study, 

playback sounds of a potential 

predator—a killer whale—resulted in a 

similar but more pronounced reaction, 

which included longer inter-dive 

intervals and a sustained straight-line 

departure of more than 20 km from the 

area (Boyd et al., 2008; Southall et al., 

2009; Tyack et al., 2011). The authors 

noted, however, that the magnified 

reaction to the predator sounds could 

represent a cumulative effect of 

exposure to the two sound types since 

killer whale playback began 

approximately two hours after MF 

source playback. Pilot whales and killer 

whales off Norway also exhibited 

horizontal avoidance of a transducer 

with outputs in the mid-frequency range 

(signals in the 1–2 kHz and 6–7 kHz 

ranges) (Miller et al., 2011). 

Additionally, separation of a calf from 

its group during exposure to MFAS 

playback was observed on one occasion 

(Miller et al., 2011, 2012). Miller et al. 

(2012) noted that this single observed 

mother-calf separation was unusual for 

several reasons, including the fact that 

the experiment was conducted in an 

unusually narrow fjord roughly one km 

wide and that the sonar exposure was 

started unusually close to the pod 

including the calf. Both of these factors 

could have contributed to calf 

separation. In contrast, preliminary 

analyses suggest that none of the pilot 

whales or false killer whales in the 

Bahamas showed an avoidance response 

to controlled exposure playbacks 

(Southall et al., 2009). 

In the 2010 BRS study, researchers 

again used controlled exposure 

experiments (CEE) to carefully measure 

behavioral responses of individual 

animals to sound exposures of MF 

active sonar and pseudo-random noise. 

For each sound type, some exposures 

were conducted when animals were in 

a surface feeding (approximately 164 ft 

(50 m) or less) and/or socializing 

behavioral state and others while 

animals were in a deep feeding (greater 

than 164 ft (50 m)) and/or traveling 

mode. The researchers conducted the 

largest number of CEEs on blue whales 

(n=19) and of these, 11 CEEs involved 

exposure to the MF active sonar sound 

type. For the majority of CEE 

transmissions of either sound type, they 

noted few obvious behavioral responses 

detected either by the visual observers 

or on initial inspection of the tag data. 

The researchers observed that 

throughout the CEE transmissions, up to 

the highest received sound level 

(absolute RMS value approximately 160 

dB re: 1mPa with signal-to-noise ratio 

values over 60 dB), two blue whales 

continued surface feeding behavior and 

remained at a range of around 3,820 ft 

(1,000 m) from the sound source 

(Southall et al., 2011). In contrast, 

another blue whale (later in the day and 

greater than 11.5 mi (18.5 km; 10 nmi) 

from the first CEE location) exposed to 

the same stimulus (MFA) while engaged 

in a deep feeding/travel state exhibited 

a different response. In that case, the 

blue whale responded almost 

immediately following the start of 

sound transmissions when received 

sounds were just above ambient 

background levels (Southall et al., 

2011). The authors note that this kind of 

temporary avoidance behavior was not 

evident in any of the nine CEEs 

involving blue whales engaged in 

surface feeding or social behaviors, but 

was observed in three of the ten CEEs 

for blue whales in deep feeding/travel 

behavioral modes (one involving MFA 

sonar; two involving pseudo-random 

noise) (Southall et al., 2011). The results 

of this study, as well as the results of the 

DeRuiter et al. (2013) study of Cuvier’s 

beaked whales discussed above, further 

illustrate the importance of behavioral 

context in understanding and predicting 

behavioral responses. 

Through analysis of the behavioral 

response studies, a preliminary 

overarching effect of greater sensitivity 

to all anthropogenic exposures was seen 

in beaked whales compared to the other 

odontocetes studied (Southall et al., 

2009). Therefore, recent studies have 

focused specifically on beaked whale 

responses to active sonar transmissions 

or controlled exposure playback of 

simulated sonar on various military 

ranges (Defence Science and 

Technology Laboratory, 2007; Claridge 

and Durban, 2009; Moretti et al., 2009; 

McCarthy et al., 2011; Miller et al., 

2012; Southall et al., 2011, 2012a, 

2012b, 2013, 2014; Tyack et al., 2011). 

In the Bahamas, Blainville’s beaked 

whales located on the instrumented 

range will move off-range during sonar 

use and return only after the sonar 

transmissions have stopped, sometimes 

taking several days to do so (Claridge 

and Durban 2009; Moretti et al., 2009; 

McCarthy et al., 2011; Tyack et al., 

2011). Moretti et al. (2014) used 

recordings from seafloor-mounted 


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hydrophones at the Atlantic Undersea 

Test and Evaluation Center (AUTEC) to 

analyze the probability of Blainsville’s 

beaked whale dives before, during, and 

after Navy sonar exercises. 

Southall et al. (2016) indicates that 

results from Tyack et al. (2011); Miller 

et al. (2015), Stimpert et al. (2014), and 

DeRuiter et al. (2013) beaked whale 

studies all demonstrate clear, strong, 

and pronounced but varied behavioral 

changes including sustained avoidance 

with associated energetic swimming and 

cessation of feeding behavior at quite 

low received levels (∼100 to 135 dB re 

1Pa) for exposures to simulated or active 

MF military sonars (1 to 8 kHz) with 

sound sources approximately 2 to 5 km 

away. 

Baleen whales have shown a variety 

of responses to impulse sound sources, 

including avoidance, reduced surface 

intervals, altered swimming behavior, 

and changes in vocalization rates 

(Richardson et al., 1995; Gordon et al., 

2003; Southall, 2007). While most 

bowhead whales did not show active 

avoidance until within 8 km of seismic 

vessels (Richardson et al., 1995), some 

whales avoided vessels by more than 20 

km at received levels as low as 120 dB 

re 1 mPa rms. Additionally, Malme et al. 

(1988) observed clear changes in diving 

and respiration patterns in bowheads at 

ranges up to 73 km from seismic vessels, 

with received levels as low as 125 dB re 

1 mPa. 

Gray whales migrating along the U.S. 

west coast showed avoidance responses 

to seismic vessels by 10 percent of 

animals at 164 dB re 1 mPa, and by 90 

percent of animals at 190 dB re 1 mPa, 

with similar results for whales in the 

Bering Sea (Malme, 1986; 1988). In 

contrast, noise from seismic surveys was 

not found to impact feeding behavior or 

exhalation rates while resting or diving 

in western gray whales off the coast of 

Russia (Yazvenko et al., 2007; Gailey et 

al., 2007). 

Humpback whales showed avoidance 

behavior at ranges of five to eight km 

from a seismic array during 

observational studies and controlled 

exposure experiments in western 

Australia (McCauley, 1998; Todd et al., 

1996). Todd found no clear short-term 

behavioral responses by foraging 

humpbacks to explosions associated 

with construction operations in 

Newfoundland, but did see a trend of 

increased rates of net entanglement and 

a shift to a higher incidence of net 

entanglement closer to the noise source. 

Orientation 

A shift in an animal’s resting state or 

an attentional change via an orienting 

response represent behaviors that would 

be considered mild disruptions if 

occurring alone. As previously 

mentioned, the responses may co-occur 

with other behaviors; for instance, an 

animal may initially orient toward a 

sound source, and then move away from 

it. Thus, any orienting response should 

be considered in context of other 

reactions that may occur. 

Continued Pre-Disturbance Behavior 

and Habituation 

Under some circumstances, some of 

the individual marine mammals that are 

exposed to active sonar transmissions 

will continue their normal behavioral 

activities. In other circumstances, 

individual animals will respond to 

sonar transmissions at lower received 

levels and move to avoid additional 

exposure or exposures at higher 

received levels (Richardson et al., 1995). 

It is difficult to distinguish between 

animals that continue their predisturbance behavior without stress 

responses, animals that continue their 

behavior but experience stress responses 

(that is, animals that cope with 

disturbance), and animals that habituate 

to disturbance (that is, they may have 

experienced low-level stress responses 

initially, but those responses abated 

over time). Watkins (1986) reviewed 

data on the behavioral reactions of fin, 

humpback, right and minke whales that 

were exposed to continuous, broadband 

low-frequency shipping and industrial 

noise in Cape Cod Bay. He concluded 

that underwater sound was the primary 

cause of behavioral reactions in these 

species of whales and that the whales 

responded behaviorally to acoustic 

stimuli within their respective hearing 

ranges. Watkins also noted that whales 

showed the strongest behavioral 

reactions to sounds in the 15 Hz to 28 

kHz range, although negative reactions 

(avoidance, interruptions in 

vocalizations, etc.) were generally 

associated with sounds that were either 

unexpected, too loud, suddenly louder 

or different, or perceived as being 

associated with a potential threat (such 

as an approaching ship on a collision 

course). In particular, whales seemed to 

react negatively when they were within 

100 m of the source or when received 

levels increased suddenly in excess of 

12 dB relative to ambient sounds. At 

other times, the whales ignored the 

source of the signal and all four species 

habituated to these sounds. 

Nevertheless, Watkins concluded that 

whales ignored most sounds in the 

background of ambient noise, including 

sounds from distant human activities 

even though these sounds may have had 

considerable energies at frequencies 

well within the whales’ range of 

hearing. Further, he noted that of the 

whales observed, fin whales were the 

most sensitive of the four species, 

followed by humpback whales; right 

whales were the least likely to be 

disturbed and generally did not react to 

low-amplitude engine noise. By the end 

of his period of study, Watkins (1986) 

concluded that fin and humpback 

whales have generally habituated to the 

continuous and broad-band noise of 

Cape Cod Bay while right whales did 

not appear to change their response. As 

mentioned above, animals that habituate 

to a particular disturbance may have 

experienced low-level stress responses 

initially, but those responses abated 

over time. In most cases, this likely 

means a lessened immediate potential 

effect from a disturbance. However, 

there is cause for concern where the 

habituation occurs in a potentially more 

harmful situation. For example, animals 

may become more vulnerable to vessel 

strikes once they habituate to vessel 

traffic (Swingle et al., 1993; Wiley et al., 

1995). 

Aicken et al. (2005) monitored the 

behavioral responses of marine 

mammals to a new low-frequency active 

sonar system used by the British Navy 

(the United States Navy considers this 

to be a mid-frequency source as it 

operates at frequencies greater than 

1,000 Hz). During those trials, fin 

whales, sperm whales, Sowerby’s 

beaked whales, long-finned pilot 

whales, Atlantic white-sided dolphins, 

and common bottlenose dolphins were 

observed and their vocalizations were 

recorded. These monitoring studies 

detected no evidence of behavioral 

responses that the investigators could 

attribute to exposure to the lowfrequency active sonar during these 

trials. 

Explosive Sources 

Underwater explosive detonations 

send a shock wave and sound energy 

through the water and can release 

gaseous by-products, create an 

oscillating bubble, or cause a plume of 

water to shoot up from the water 

surface. The shock wave and 

accompanying noise are of most concern 

to marine animals. Depending on the 

intensity of the shock wave and size, 

location, and depth of the animal, an 

animal can be injured, killed, suffer 

non-lethal physical effects, experience 

hearing related effects with or without 

behavioral responses, or exhibit 

temporary behavioral responses or 

tolerance from hearing the blast sound. 

Generally, exposures to higher levels of 

impulse and pressure levels would 

result in greater impacts to an 

individual animal. 


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Injuries resulting from a shock wave 

take place at boundaries between tissues 

of different densities. Different 

velocities are imparted to tissues of 

different densities, and this can lead to 

their physical disruption. Blast effects 

are greatest at the gas-liquid interface 

(Landsberg, 2000). Gas-containing 

organs, particularly the lungs and 

gastrointestinal tract, are especially 

susceptible (Goertner, 1982; Hill, 1978; 

Yelverton et al., 1973). Intestinal walls 

can bruise or rupture, with subsequent 

hemorrhage and escape of gut contents 

into the body cavity. Less severe 

gastrointestinal tract injuries include 

contusions, petechiae (small red or 

purple spots caused by bleeding in the 

skin), and slight hemorrhaging 

(Yelverton et al., 1973). 

Because the ears are the most 

sensitive to pressure, they are the organs 

most sensitive to injury (Ketten, 2000). 

Sound-related damage associated with 

sound energy from detonations can be 

theoretically distinct from injury from 

the shock wave, particularly farther 

from the explosion. If a noise is audible 

to an animal, it has the potential to 

damage the animal’s hearing by causing 

decreased sensitivity (Ketten, 1995). 

Lethal impacts are those that result in 

immediate death or serious debilitation 

in or near an intense source and are not, 

technically, pure acoustic trauma 

(Ketten, 1995). Sublethal impacts 

include hearing loss, which is caused by 

exposures to perceptible sounds. Severe 

damage (from the shock wave) to the 

ears includes tympanic membrane 

rupture, fracture of the ossicles, damage 

to the cochlea, hemorrhage, and 

cerebrospinal fluid leakage into the 

middle ear. Moderate injury implies 

partial hearing loss due to tympanic 

membrane rupture and blood in the 

middle ear. Permanent hearing loss also 

can occur when the hair cells are 

damaged by one very loud event, as well 

as by prolonged exposure to a loud 

noise or chronic exposure to noise. The 

level of impact from blasts depends on 

both an animal’s location and, at outer 

zones, on its sensitivity to the residual 

noise (Ketten, 1995). 

Further Potential Effects of Behavioral 

Disturbance on Marine Mammal Fitness 

The different ways that marine 

mammals respond to sound are 

sometimes indicators of the ultimate 

effect that exposure to a given stimulus 

will have on the well-being (survival, 

reproduction, etc.) of an animal. There 

are few quantitative marine mammal 

data relating the exposure of marine 

mammals to sound to effects on 

reproduction or survival, though data 

exists for terrestrial species to which we 

can draw comparisons for marine 

mammals. Several authors have 

reported that disturbance stimuli may 

cause animals to abandon nesting and 

foraging sites (Sutherland and 

Crockford, 1993); may cause animals to 

increase their activity levels and suffer 

premature deaths or reduced 

reproductive success when their energy 

expenditures exceed their energy 

budgets (Daan et al., 1996; Feare, 1976; 

Mullner et al., 2004); or may cause 

animals to experience higher predation 

rates when they adopt risk-prone 

foraging or migratory strategies (Frid 

and Dill, 2002). Each of these studies 

addressed the consequences of animals 

shifting from one behavioral state (e.g., 

resting or foraging) to another 

behavioral state (e.g., avoidance or 

escape behavior) because of human 

disturbance or disturbance stimuli. 

One consequence of behavioral 

avoidance results in the altered 

energetic expenditure of marine 

mammals because energy is required to 

move and avoid surface vessels or the 

sound field associated with active sonar 

(Frid and Dill, 2002). Most animals can 

avoid that energetic cost by swimming 

away at slow speeds or speeds that 

minimize the cost of transport (MiksisOlds, 2006), as has been demonstrated 

in Florida manatees (Miksis-Olds, 2006). 

Those energetic costs increase, 

however, when animals shift from a 

resting state, which is designed to 

conserve an animal’s energy, to an 

active state that consumes energy the 

animal would have conserved had it not 

been disturbed. Marine mammals that 

have been disturbed by anthropogenic 

noise and vessel approaches are 

commonly reported to shift from resting 

to active behavioral states, which would 

imply that they incur an energy cost. 

Morete et al. (2007) reported that 

undisturbed humpback whale cows that 

were accompanied by their calves were 

frequently observed resting while their 

calves circled them (milling). When 

vessels approached, the amount of time 

cows and calves spent resting and 

milling, respectively, declined 

significantly. These results are similar to 

those reported by Scheidat et al. (2004) 

for the humpback whales they observed 

off the coast of Ecuador. 

Constantine and Brunton (2001) 

reported that bottlenose dolphins in the 

Bay of Islands, New Zealand engaged in 

resting behavior just 5 percent of the 

time when vessels were within 300 m, 

compared with 83 percent of the time 

when vessels were not present. 

However, Heenehan et al. (2016) report 

that results of a study of the response of 

Hawaiian spinner dolphins to human 

disturbance suggest that the key factor is 

not the sheer presence or magnitude of 

human activities, but rather the directed 

interactions and dolphin-focused 

activities that elicit responses from 

dolphins at rest. This information again 

illustrates the importance of context in 

regard to whether an animal will 

respond to a stimulus. Miksis-Olds 

(2006) and Miksis-Olds et al. (2005) 

reported that Florida manatees in 

Sarasota Bay, Florida, reduced the 

amount of time they spent milling and 

increased the amount of time they spent 

feeding when background noise levels 

increased. Although the acute costs of 

these changes in behavior are not likely 

to exceed an animal’s ability to 

compensate, the chronic costs of these 

behavioral shifts are uncertain. 

Attention is the cognitive process of 

selectively concentrating on one aspect 

of an animal’s environment while 

ignoring other things (Posner, 1994). 

Because animals (including humans) 

have limited cognitive resources, there 

is a limit to how much sensory 

information they can process at any 

time. The phenomenon called 

‘‘attentional capture’’ occurs when a 

stimulus (usually a stimulus that an 

animal is not concentrating on or 

attending to) ‘‘captures’’ an animal’s 

attention. This shift in attention can 

occur consciously or subconsciously 

(for example, when an animal hears 

sounds that it associates with the 

approach of a predator) and the shift in 

attention can be sudden (Dukas, 2002; 

van Rij, 2007). Once a stimulus has 

captured an animal’s attention, the 

animal can respond by ignoring the 

stimulus, assuming a ‘‘watch and wait’’ 

posture, or treat the stimulus as a 

disturbance and respond accordingly, 

which includes scanning for the source 

of the stimulus or ‘‘vigilance’’ 

(Cowlishaw et al., 2004). 

Vigilance is normally an adaptive 

behavior that helps animals determine 

the presence or absence of predators, 

assess their distance from conspecifics, 

or to attend cues from prey (Bednekoff 

and Lima, 1998; Treves, 2000). Despite 

those benefits, however, vigilance has a 

cost of time; when animals focus their 

attention on specific environmental 

cues, they are not attending to other 

activities such as foraging. These costs 

have been documented best in foraging 

animals, where vigilance has been 

shown to substantially reduce feeding 

rates (Saino, 1994; Beauchamp and 

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

Animals will spend more time being 

vigilant, which may translate to less 

time foraging or resting, when 

disturbance stimuli approach them 

more directly, remain at closer 

distances, have a greater group size (e.g., 


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multiple surface vessels), or when they 

co-occur with times that an animal 

perceives increased risk (e.g., when they 

are giving birth or accompanied by a 

calf). Most of the published literature, 

however, suggests that direct 

approaches will increase the amount of 

time animals will dedicate to being 

vigilant. An example of this concept 

with terrestrial species involved bighorn 

sheep and Dall’s sheep, which 

dedicated more time being vigilant, and 

less time resting or foraging, when 

aircraft made direct approaches over 

them (Frid, 2001; Stockwell et al., 

1991). Vigilance has also been 

documented in pinnipeds at haul out 

sites where resting may be disturbed 

when seals become alerted and/or flush 

into the water due to a variety of 

disturbances, which may be 

anthropogenic (noise and/or visual 

stimuli) or due to other natural causes 

such as other pinnipeds (Richardson et 

al., 1995; Southall et al., 2007; 

VanBlaricom, 2010; and Lozano and 

Hente, 2014). 

Several authors have established that 

long-term and intense disturbance 

stimuli can cause population declines 

by reducing the physical condition of 

individuals that have been disturbed, 

followed by reduced reproductive 

success, reduced survival, or both (Daan 

et al., 1996; Madsen, 1994; White, 

1985). For example, Madsen (1994) 

reported that pink-footed geese (Anser 

brachyrhynchus) in undisturbed habitat 

gained body mass and had about a 46 

percent reproductive success rate 

compared with geese in disturbed 

habitat (being consistently scared off the 

fields on which they were foraging) 

which did not gain mass and had a 17 

percent reproductive success rate. 

Similar reductions in reproductive 

success have been reported for mule 

deer (Odocoileus hemionus) disturbed 

by all-terrain vehicles (Yarmoloy et al., 

1988), caribou (Rangifer tarandus 

caribou) disturbed by seismic 

exploration blasts (Bradshaw et al., 

1998), and caribou disturbed by lowelevation military jet fights (Luick et al., 

1996, Harrington and Veitch, 1992). 

Similarly, a study of elk (Cervus 

elaphus) that were disturbed 

experimentally by pedestrians 

concluded that the ratio of young to 

mothers was inversely related to 

disturbance rate (Phillips and 

Alldredge, 2000). 

The primary mechanism by which 

increased vigilance and disturbance 

appear to affect the fitness of individual 

animals is by disrupting an animal’s 

time budget and, as a result, reducing 

the time they might spend foraging and 

resting (which increases an animal’s 

activity rate and energy demand while 

decreasing their caloric intake/energy). 

Ridgway et al. (2006) reported that 

increased vigilance in bottlenose 

dolphins exposed to sound over a fiveday period in open-air, open-water 

enclosures in San Diego Bay did not 

cause any sleep deprivation or stress 

effects such as changes in cortisol or 

epinephrine levels. An example of this 

concept with terrestrial species involved 

a study of grizzly bears (Ursus horribilis) 

that reported that bears disturbed by 

hikers reduced their energy intake by an 

average of 12 kilocalories/min (50.2 × 

103 kiloJoules/min), and spent energy 

fleeing or acting aggressively toward 

hikers (White et al., 1999). 

Lusseau and Bejder (2007) present 

data from three long-term studies 

illustrating the connections between 

disturbance from whale-watching boats 

and population-level effects in 

cetaceans. In Sharks Bay Australia, the 

abundance of bottlenose dolphins was 

compared within adjacent control and 

tourism sites over three consecutive 4.5- 

year periods of increasing tourism 

levels. Between the second and third 

time periods, in which tourism doubled, 

dolphin abundance decreased by 15 

percent in the tourism area and did not 

change significantly in the control area. 

In Fiordland, New Zealand, two 

populations (Milford and Doubtful 

Sounds) of bottlenose dolphins with 

tourism levels that differed by a factor 

of seven were observed and significant 

increases in travelling time and 

decreases in resting time were 

documented for both. Consistent shortterm avoidance strategies were observed 

in response to tour boats until a 

threshold of disturbance was reached 

(average 68 minutes between 

interactions), after which the response 

switched to a longer-term habitat 

displacement strategy. For one 

population, tourism only occurred in a 

part of the home range. However, 

tourism occurred throughout the home 

range of the Doubtful Sound population 

and once boat traffic increased beyond 

the 68-minute threshold (resulting in 

abandonment of their home range/ 

preferred habitat), reproductive success 

drastically decreased (increased 

stillbirths) and abundance decreased 

significantly (from 67 to 56 individuals 

in short period). Last, in a study of 

northern resident killer whales off 

Vancouver Island, exposure to boat 

traffic was shown to reduce foraging 

opportunities and increase traveling 

time. A simple bioenergetics model was 

applied to show that the reduced 

foraging opportunities equated to a 

decreased energy intake of 18 percent, 

while the increased traveling incurred 

an increased energy output of 3–4 

percent, which suggests that a 

management action based on avoiding 

interference with foraging might be 

particularly effective. 

On a related note, many animals 

perform vital functions, such as feeding, 

resting, traveling, and socializing, on a 

diel cycle (24-hr cycle). Behavioral 

reactions to noise exposure (such as 

disruption of critical life functions, 

displacement, or avoidance of important 

habitat) are more likely to be significant 

for fitness 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). It is important to 

note the difference between behavioral 

reactions lasting or recurring over 

multiple days and anthropogenic 

activities lasting or recurring over 

multiple days. For example, just 

because an at-sea exercises last for 

multiple days does not necessarily mean 

that individual animals will be exposed 

to those exercises for multiple days or 

exposed in a manner that would result 

in a sustained behavioral response. 

In order to understand how the effects 

of activities may or may not impact 

species and stocks of marine mammals, 

it is necessary to understand not only 

what the likely disturbances are going to 

be, but how those disturbances may 

affect the reproductive success and 

survivorship of individuals, and then 

how those impacts to individuals 

translate to population-level effects. 

Following on the earlier work of a 

committee of the U.S. National Research 

Council (NRC, 2005), New et al. (2014), 

in an effort termed the Potential 

Consequences of Disturbance (PCoD), 

outline an updated conceptual model of 

the relationships linking disturbance to 

changes in behavior and physiology, 

health, vital rates, and population 

dynamics. In this framework, behavioral 

and physiological changes can either 

have direct (acute) effects on vital rates, 

such as when changes in habitat use or 

increased stress levels raise the 

probability of mother-calf separation or 

predation; they can have indirect and 

long-term (chronic) effects on vital rates, 

such as when changes in time/energy 

budgets or increased disease 

susceptibility affect health, which then 

affects vital rates; or they can have no 

effect to vital rates (New et al., 2014). In 

addition to outlining this general 

framework and compiling the relevant 

literature that supports it, authors have 


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chosen four example species for which 

extensive long-term monitoring data 

exist (southern elephant seals, North 

Atlantic right whales, Ziphidae beaked 

whales, and bottlenose dolphins) and 

developed state-space energetic models 

that can be used to effectively forecast 

longer-term, population-level impacts 

from behavioral changes. While these 

are very specific models with very 

specific data requirements that cannot 

yet be applied broadly to projectspecific risk assessments for the 

majority of species, they are a critical 

first step towards being able to quantify 

the likelihood of a population level 

effect. 

Stranding and Mortality 

The definition for a stranding under 

title IV of the MMPA is that (A) a marine 

mammal is dead and is (i) on a beach 

or shore of the United States; or (ii) in 

waters under the jurisdiction of the 

United States (including any navigable 

waters); or (B) a marine mammal is alive 

and is (i) on a beach or shore of the 

United States and is unable to return to 

the water; (ii) on a beach or shore of the 

United States and, although able to 

return to the water, is in need of 

apparent medical attention; or (iii) in 

the waters under the jurisdiction of the 

United States (including any navigable 

waters), but is unable to return to its 

natural habitat under its own power or 

without assistance (16 U.S.C. 1421h). 

Marine mammal strandings have been 

linked to a variety of causes, such as 

illness from exposure to infectious 

agents, biotoxins, or parasites; 

starvation; unusual oceanographic or 

weather events; or anthropogenic causes 

including fishery interaction, ship 

strike, entrainment, entrapment, sound 

exposure, or combinations of these 

stressors sustained concurrently or in 

series. Historically, the cause or causes 

of most strandings have remained 

unknown (Geraci et al., 1976; Eaton, 

1979, Odell et al., 1980; Best, 1982), but 

the development of trained, professional 

stranding response networks and 

improved analyses have led to a greater 

understanding of marine mammal 

stranding causes (Simeone and Moore in 

press). 

Numerous studies suggest that the 

physiology, behavior, habitat, social, 

relationships, age, or condition of 

cetaceans may cause them to strand or 

might pre-dispose them to strand when 

exposed to another phenomenon. These 

suggestions are consistent with the 

conclusions of numerous other studies 

that have demonstrated that 

combinations of dissimilar stressors 

commonly combine to kill an animal or 

dramatically reduce its fitness, even 

though one exposure without the other 

does not produce the same result 

(Chroussos, 2000; Creel, 2005; DeVries 

et al., 2003; Fair and Becker, 2000; Foley 

et al., 2001; Moberg, 2000; Relyea, 

2005a; 2005b, Romero, 2004; Sih et al., 

2004). 

Historically, stranding reporting and 

response efforts have been inconsistent, 

although significant improvements have 

occurred over the last 25 years. 

Reporting forms for basic (‘‘Level A’’) 

information, rehabilitation disposition, 

and Human Interaction have been 

standardized nationally (available at 

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

national/marine-mammal-protection/ 

level-data-collection-marine-mammalstranding-events). However, data 

collected beyond basic information 

varies by region (and may vary from 

case to case), and are not standardized 

across the United States. Logistical 

conditions such as weather, time, 

location, and decomposition state may 

also affect the ability of the stranding 

network to thoroughly examine a 

specimen (Carretta et al., 2016b; Moore 

et al., 2013). While the investigation of 

stranded animals provides insight into 

the types of threats marine mammal 

populations face, full investigations are 

only possible and conducted on a small 

fraction of the total number of 

strandings that occur, limiting our 

understanding of the causes of 

strandings (Carretta et al., 2016a). 

Additionally, and due to the variability 

in effort and data collected, the ability 

to interpret long-term trends in stranded 

marine mammals is complicated. 

Along the coasts of the continental 

United States and Alaska between 2001 

and 2009, there were on average 

approximately 12,545 cetacean 

strandings and 39,104 pinniped 

strandings (51,649 total) per year 

(National Marine Fisheries Service, 

2016i). Several mass strandings 

(strandings that involve two or more 

individuals of the same species, 

excluding a single mother-calf pair) that 

have occurred over the past two decades 

have been associated with 

anthropogenic activities that introduced 

sound into the marine environment 

such as naval operations and seismic 

surveys. An in-depth discussion of 

strandings is in the Navy’s Technical 

Report on Marine Mammal Strandings 

Associated with U.S. Navy Sonar 

Activities (U.S. Navy Marine Mammal 

Program & Space and Naval Warfare 

Systems Command Center Pacific, 

2017). 

Worldwide, there have been several 

efforts to identify relationships between 

cetacean mass stranding events and 

military active sonar (Cox et al., 2006, 

Hildebrand, 2004; IWC, 2005; Taylor et 

al., 2004). For example, based on a 

review of mass stranding events around 

the world consisting of two or more 

individuals of Cuvier’s beaked whales, 

records from the International Whaling 

Commission (IWC)(2005) show that a 

quarter (9 of 41) were associated with 

concurrent naval patrol, explosion, 

maneuvers, or MFAS. D’Amico et al. 

(2009) reviewed beaked whale stranding 

data compiled primarily from the 

published literature, which provides an 

incomplete record of stranding events, 

as many are not written up for 

publication, along with unpublished 

information from some regions of the 

world. 

Most of the stranding events reviewed 

by the IWC involved beaked whales. A 

mass stranding of Cuvier’s beaked 

whales in the eastern Mediterranean Sea 

occurred in 1996 (Frantzis, 1998) and 

mass stranding events involving 

Gervais’ beaked whales, Blainville’s 

beaked whales, and Cuvier’s beaked 

whales occurred off the coast of the 

Canary Islands in the late 1980s 

(Simmonds and Lopez-Jurado, 1991). 

The stranding events that occurred in 

the Canary Islands and Kyparissiakos 

Gulf in the late 1990s and the Bahamas 

in 2000 have been the most intensivelystudied mass stranding events and have 

been associated with naval maneuvers 

involving the use of tactical sonar. Other 

cetacean species with naval sonar 

implicated in stranding events include 

harbor porpoise (Phocoena phocoena) 

(Norman et al., 2004, Wright et al., 

2013) and common dolphin (Delphinus 

delphis) (Jepson and Deaville 2009). 

Strandings Associated With Impulsive 

Sound 

Silver Strand 

During a Navy training event on 

March 4, 2011 at the Silver Strand 

Training Complex in San Diego, 

California, three or possibly four 

dolphins were killed in an explosion. 

During an underwater detonation 

training event, a pod of 100 to 150 longbeaked common dolphins were 

observed moving towards the 700-yd 

(640.1 m) exclusion zone around the 

explosive charge, monitored by 

personnel in a safety boat and 

participants in a dive boat. 

Approximately five minutes remained 

on a time-delay fuse connected to a 

single 8.76 lb (3.97 kg) explosive charge 

(C–4 and detonation cord). Although the 

dive boat was placed between the pod 

and the explosive in an effort to guide 

the dolphins away from the area, that 

effort was unsuccessful and three longbeaked common dolphins near the 


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explosion died. In addition to the three 

dolphins found dead on March 4, the 

remains of a fourth dolphin were 

discovered on March 7, 2011 near 

Oceanside, California (3 days later and 

approximately 68 km north of the 

detonation), which might also have been 

related to this event. Association of the 

fourth stranding with the training event 

is uncertain because dolphins strand on 

a regular basis in the San Diego area. 

Details such as the dolphins’ depth and 

distance from the explosive at the time 

of the detonation could not be estimated 

from the 250 yd (228.6 m) standoff point 

of the observers in the dive boat or the 

safety boat. 

These dolphin mortalities are the only 

known occurrence of a U.S. Navy 

training or testing event involving 

impulsive energy (underwater 

detonation) that caused mortality or 

injury to a marine mammal. Despite this 

being a rare occurrence, the Navy has 

reviewed training requirements, safety 

procedures, and possible mitigation 

measures and implemented changes to 

reduce the potential for this to occur in 

the future. Discussions of procedures 

associated with underwater explosives 

training and other training events are 

presented in the Proposed Mitigation 

section. 

Kyle of Durness, Scotland 

On July 22, 2011 a mass stranding 

event involving long-finned pilot 

whales occurred at Kyle of Durness, 

Scotland. An investigation by Brownlow 

et al. (2015) considered unexploded 

ordnance detonation activities at a 

Ministry of Defense bombing range, 

conducted by the Royal Navy prior to 

and during the strandings, as a plausible 

contributing factor in the mass stranding 

event. While Brownlow et al. (2015) 

concluded that the serial detonations of 

underwater ordnance were an 

influential factor in the mass stranding 

event (along with presence of a 

potentially compromised animal and 

navigational error in a topographically 

complex region) they also suggest that 

mitigation measures—which included 

observations from a zodiac only and by 

personnel not experienced in marine 

mammal observation, among other 

deficiencies—were likely insufficient to 

assess if cetaceans were in the vicinity 

of the detonations. The authors also cite 

information from the Ministry of 

Defense indicating ‘‘an extraordinarily 

high level of activity’’ (i.e., frequency 

and intensity of underwater explosions) 

on the range in the days leading up to 

the stranding. 

Gulf of California, Mexico 

One stranding event was 

contemporaneous with and reasonably 

associated spatially with the use of 

seismic air guns. This event occurred in 

the Gulf of California, coincident with 

seismic reflection profiling by the R/V 

Maurice Ewing operated by Columbia 

University’s Lamont-Doherty Earth 

Observatory and involved two Cuvier’s 

beaked whales (Hildebrand, 2004). The 

vessel had been firing an array of 20 air 

guns with a total volume of 8,500 in3

(Hildebrand, 2004; Taylor et al., 2004). 

Strandings Associated With Active 

Sonar 

Over the past 21 years, there have 

been five stranding events coincident 

with military MF active sonar use in 

which exposure to sonar is believed to 

have been a contributing factor: Greece 

(1996); the Bahamas (2000); Madeira 

(2000); Canary Islands (2002); and Spain 

(2006) (Cox et al., 2006; Fernandez, 

2006; U.S. Navy Marine Mammal 

Program & Space and Naval Warfare 

Systems Command Center Pacific, 

2017). These five mass strandings have 

resulted in about 40 known cetacean 

deaths consisting mostly of beaked 

whales and with close linkages to midfrequency active sonar activity. In these 

circumstances, exposure to nonimpulsive acoustic energy was 

considered a potential indirect cause of 

death of the marine mammals (Cox et 

al., 2006). Only one of these stranding 

events, the Bahamas (2000), was 

associated with exercises conducted by 

the U.S. Navy. Additionally, in 2004, 

during the Rim of the Pacific (RIMPAC) 

exercises, between 150 and 200 usually 

pelagic melon-headed whales occupied 

the shallow waters of Hanalei Bay, 

Kauai, Hawaii for over 28 hours. NMFS 

determined that MFAS was a plausible, 

if not likely, contributing factor in what 

may have been a confluence of events 

that led to the Hanalei Bay stranding. A 

number of other stranding events 

coincident with the operation of MFAS, 

including the death of beaked whales or 

other species (minke whales, dwarf 

sperm whales, pilot whales), have been 

reported; however, the majority have 

not been investigated to the degree 

necessary to determine the cause of the 

stranding. Most recently, the 

Independent Scientific Review Panel 

investigating potential contributing 

factors to a 2008 mass stranding of 

melon-headed whales in Antsohihy, 

Madagascar released its final report 

suggesting that the stranding was likely 

initially triggered by an industry seismic 

survey. This report suggests that the 

operation of a commercial high-powered 

12 kHz multi-beam echosounder during 

an industry seismic survey was a 

plausible and likely initial trigger that 

caused a large group of melon-headed 

whales to leave their typical habitat and 

then ultimately strand as a result of 

secondary factors such as 

malnourishment and dehydration. The 

report indicates that the risk of this 

particular convergence of factors and 

ultimate outcome is likely very low, but 

recommends that the potential be 

considered in environmental planning. 

Because of the association between 

tactical mid-frequency active sonar use 

and a small number of marine mammal 

strandings, the Navy and NMFS have 

been considering and addressing the 

potential for strandings in association 

with Navy activities for years. In 

addition to the proposed mitigation 

measures intended to more broadly 

minimize impacts to marine mammals, 

the Navy will abide by the Notification 

and Reporting Plan, which sets out 

notification, reporting, and other 

requirements when dead, injured, or 

stranding whales are detected in certain 

circumstances. 

Greece (1996) 

Twelve Cuvier’s beaked whales 

stranded atypically (in both time and 

space) along a 38.2-km strand of the 

Kyparissiakos Gulf coast on May 12 and 

13, 1996 (Frantzis, 1998). From May 11 

through May 15, the North Atlantic 

Treaty Organization (NATO) research 

vessel Alliance was conducting sonar 

tests with signals of 600 Hz and 3 kHz 

and source levels of 228 and 226 dB re: 

1mPa, respectively (D’Amico and 

Verboom, 1998; D’Spain et al., 2006). 

The timing and location of the testing 

encompassed the time and location of 

the strandings (Frantzis, 1998). 

Necropsies of eight of the animals 

were performed but were limited to 

basic external examination and 

sampling of stomach contents, blood, 

and skin. No ears or organs were 

collected, and no histological samples 

were preserved. No apparent 

abnormalities or wounds were found. 

Examination of photos of the animals, 

taken soon after their death, revealed 

that the eyes of at least four of the 

individuals were bleeding. Photos were 

taken soon after their death (Frantzis, 

2004). Stomach contents contained the 

flesh of cephalopods, indicating that 

feeding had recently taken place 

(Frantzis, 1998). 

All available information regarding 

the conditions associated with this 

stranding event were compiled, and 

many potential causes were examined 

including major pollution events, 

prominent tectonic activity, unusual 


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physical or meteorological events, 

magnetic anomalies, epizootics, and 

conventional military activities 

(International Council for the 

Exploration of the Sea, 2005a). 

However, none of these potential causes 

coincided in time or space with the 

mass stranding, or could explain its 

characteristics (International Council for 

the Exploration of the Sea, 2005a). The 

robust condition of the animals, plus the 

recent stomach contents, is inconsistent 

with pathogenic causes. In addition, 

environmental causes can be ruled out 

as there were no unusual environmental 

circumstances or events before or during 

this time period and within the general 

proximity (Frantzis, 2004). 

Because of the rarity of this mass 

stranding of Cuvier’s beaked whales in 

the Kyparissiakos Gulf (first one in 

historical records), the probability for 

the two events (the military exercises 

and the strandings) to coincide in time 

and location, while being independent 

of each other, was thought to be 

extremely low (Frantzis, 1998). 

However, because full necropsies had 

not been conducted, and no 

abnormalities were noted, the cause of 

the strandings could not be precisely 

determined (Cox et al., 2006). A 

Bioacoustics Panel convened by NATO 

concluded that the evidence available 

did not allow them to accept or reject 

sonar exposures as a causal agent in 

these stranding events. The analysis of 

this stranding event provided support 

for, but no clear evidence for, the causeand-effect relationship of tactical sonar 

training activities and beaked whale 

strandings (Cox et al., 2006). 

Bahamas (2000) 

NMFS and the Navy prepared a joint 

report addressing the multi-species 

stranding in the Bahamas in 2000, 

which took place within 24 hrs of U.S. 

Navy ships using MFAS as they passed 

through the Northeast and Northwest 

Providence Channels on March 15–16, 

2000. The ships, which operated both 

AN/SQS–53C and AN/SQS–56, moved 

through the channel while emitting 

sonar pings approximately every 24 

seconds. Of the 17 cetaceans that 

stranded over a 36-hr period (Cuvier’s 

beaked whales, Blainville’s beaked 

whales, minke whales, and a spotted 

dolphin), seven animals died on the 

beach (five Cuvier’s beaked whales, one 

Blainville’s beaked whale, and the 

spotted dolphin), while the other 10 

were returned to the water alive (though 

their ultimate fate is unknown). As 

discussed in the Bahamas report (DOC/ 

DON, 2001), there is no likely 

association between the minke whale 

and spotted dolphin strandings and the 

operation of MFAS. 

Necropsies were performed on five of 

the stranded beaked whales. All five 

necropsied beaked whales were in good 

body condition, showing no signs of 

infection, disease, ship strike, blunt 

trauma, or fishery related injuries, and 

three still had food remains in their 

stomachs. Auditory structural damage 

was discovered in four of the whales, 

specifically bloody effusions or 

hemorrhaging around the ears. Bilateral 

intracochlear and unilateral temporal 

region subarachnoid hemorrhage, with 

blood clots in the lateral ventricles, 

were found in two of the whales. Three 

of the whales had small hemorrhages in 

their acoustic fats (located along the jaw 

and in the melon). 

A comprehensive investigation was 

conducted and all possible causes of the 

stranding event were considered, 

whether they seemed likely at the outset 

or not. Based on the way in which the 

strandings coincided with ongoing 

naval activity involving tactical MFAS 

use, in terms of both time and 

geography, the nature of the 

physiological effects experienced by the 

dead animals, and the absence of any 

other acoustic sources, the investigation 

team concluded that MFAS aboard U.S. 

Navy ships that were in use during the 

active sonar exercise in question were 

the most plausible source of this 

acoustic or impulse trauma to beaked 

whales. This sound source was active in 

a complex environment that included 

the presence of a surface duct, unusual 

and steep bathymetry, a constricted 

channel with limited egress, intensive 

use of multiple, active sonar units over 

an extended period of time, and the 

presence of beaked whales that appear 

to be sensitive to the frequencies 

produced by these active sonars. The 

investigation team concluded that the 

cause of this stranding event was the 

confluence of the Navy MFAS and these 

contributory factors working together, 

and further recommended that the Navy 

avoid operating MFAS in situations 

where these five factors would be likely 

to occur. This report does not conclude 

that all five of these factors must be 

present for a stranding to occur, nor that 

beaked whales are the only species that 

could potentially be affected by the 

confluence of the other factors. Based on 

this, NMFS believes that the operation 

of MFAS in situations where surface 

ducts exist, or in marine environments 

defined by steep bathymetry and/or 

constricted channels may increase the 

likelihood of producing a sound field 

with the potential to cause cetaceans 

(especially beaked whales) to strand, 

and therefore, suggests the need for 

increased vigilance while operating 

MFAS in these areas, especially when 

beaked whales (or potentially other 

deep divers) are likely present. 

Madeira, Portugal (2000) 

From May 10–14, 2000, three Cuvier’s 

beaked whales were found atypically 

stranded on two islands in the Madeira 

archipelago, Portugal (Cox et al., 2006). 

A fourth animal was reported floating in 

the Madeiran waters by fisherman but 

did not come ashore (Woods Hole 

Oceanographic Institution, 2005). Joint 

NATO amphibious training 

peacekeeping exercises involving 

participants from 17 countries and 80 

warships, took place in Portugal during 

May 2–15, 2000. 

The bodies of the three stranded 

whales were examined post mortem 

(Woods Hole Oceanographic Institution, 

2005), though only one of the stranded 

whales was fresh enough (24 hours after 

stranding) to be necropsied (Cox et al., 

2006). Results from the necropsy 

revealed evidence of hemorrhage and 

congestion in the right lung and both 

kidneys (Cox et al., 2006). There was 

also evidence of intercochlear and 

intracranial hemorrhage similar to that 

which was observed in the whales that 

stranded in the Bahamas event (Cox et 

al., 2006). There were no signs of blunt 

trauma, and no major fractures (Woods 

Hole Oceanographic Institution, 2005). 

The cranial sinuses and airways were 

found to be clear with little or no fluid 

deposition, which may indicate good 

preservation of tissues (Woods Hole 

Oceanographic Institution, 2005). 

Several observations on the Madeira 

stranded beaked whales, such as the 

pattern of injury to the auditory system, 

are the same as those observed in the 

Bahamas strandings. Blood in and 

around the eyes, kidney lesions, pleural 

hemorrhages, and congestion in the 

lungs are particularly consistent with 

the pathologies from the whales 

stranded in the Bahamas, and are 

consistent with stress and pressure 

related trauma. The similarities in 

pathology and stranding patterns 

between these two events suggest that a 

similar pressure event may have 

precipitated or contributed to the 

strandings at both sites (Woods Hole 

Oceanographic Institution, 2005). 

Even though no definitive causal link 

can be made between the stranding 

event and naval exercises, certain 

conditions may have existed in the 

exercise area that, in their aggregate, 

may have contributed to the marine 

mammal strandings (Freitas, 2004): 

Exercises were conducted in areas of at 

least 547 fathoms (1,000 m) depth near 

a shoreline where there is a rapid 


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change in bathymetry on the order of 

547 to 3,281 fathoms (1,000 to 6,000 m) 

occurring across a relatively short 

horizontal distance (Freitas, 2004); 

multiple ships were operating around 

Madeira, though it is not known if 

MFAS was used, and the specifics of the 

sound sources used are unknown (Cox 

et al., 2006, Freitas, 2004); and exercises 

took place in an area surrounded by 

landmasses separated by less than 35 

nmi (65 km) and at least 10 nmi (19 km) 

in length, or in an embayment. Exercises 

involving multiple ships employing 

MFAS near land may produce sound 

directed towards a channel or 

embayment that may cut off the lines of 

egress for marine mammals (Freitas, 

2004). 

Canary Islands, Spain (2002) 

The southeastern area within the 

Canary Islands is well known for 

aggregations of beaked whales due to its 

ocean depths of greater than 547 

fathoms (1,000 m) within a few hundred 

meters of the coastline (Fernandez et al., 

2005). On September 24, 2002, 14 

beaked whales were found stranded on 

Fuerteventura and Lanzarote Islands in 

the Canary Islands (International 

Council for Exploration of the Sea, 

2005a). Seven whales died, while the 

remaining seven live whales were 

returned to deeper waters (Fernandez et 

al., 2005). Four beaked whales were 

found stranded dead over the next three 

days either on the coast or floating 

offshore. These strandings occurred 

within near proximity of an 

international naval exercise that utilized 

MFAS and involved numerous surface 

warships and several submarines. 

Strandings began about four hours after 

the onset of MFAS activity 

(International Council for Exploration of 

the Sea, 2005a; Fernandez et al., 2005). 

Eight Cuvier’s beaked whales, one 

Blainville’s beaked whale, and one 

Gervais’ beaked whale were necropsied, 

6 of them within 12 hours of stranding 

(Fernandez et al., 2005). No pathogenic 

bacteria were isolated from the carcasses 

(Jepson et al., 2003). The animals 

displayed severe vascular congestion 

and hemorrhage especially around the 

tissues in the jaw, ears, brain, and 

kidneys, displaying marked 

disseminated microvascular 

hemorrhages associated with 

widespread fat emboli (Jepson et al., 

2003; International Council for 

Exploration of the Sea, 2005a). Several 

organs contained intravascular bubbles, 

although definitive evidence of gas 

embolism in vivo is difficult to 

determine after death (Jepson et al., 

2003). The livers of the necropsied 

animals were the most consistently 

affected organ, which contained 

macroscopic gas-filled cavities and had 

variable degrees of fibrotic 

encapsulation. In some animals, 

cavitary lesions had extensively 

replaced the normal tissue (Jepson et al., 

2003). Stomachs contained a large 

amount of fresh and undigested 

contents, suggesting a rapid onset of 

disease and death (Fernandez et al., 

2005). Head and neck lymph nodes 

were enlarged and congested, and 

parasites were found in the kidneys of 

all animals (Fernandez et al., 2005). 

The association of NATO MFAS use 

close in space and time to the beaked 

whale strandings, and the similarity 

between this stranding event and 

previous beaked whale mass strandings 

coincident with sonar use, suggests that 

a similar scenario and causative 

mechanism of stranding may be shared 

between the events. Beaked whales 

stranded in this event demonstrated 

brain and auditory system injuries, 

hemorrhages, and congestion in 

multiple organs, similar to the 

pathological findings of the Bahamas 

and Madeira stranding events. In 

addition, the necropsy results of Canary 

Islands stranding event lead to the 

hypothesis that the presence of 

disseminated and widespread gas 

bubbles and fat emboli were indicative 

of nitrogen bubble formation, similar to 

what might be expected in 

decompression sickness (Jepson et al., 

2003; Ferna ́ndez et al., 2005). 

Hanalei Bay (2004) 

On July 3 and 4, 2004, approximately 

150 to 200 melon-headed whales 

occupied the shallow waters of the 

Hanalei Bay, Kauai, Hawaii for over 28 

hrs. Attendees of a canoe blessing 

observed the animals entering the Bay 

in a single wave formation at 7 a.m. on 

July 3, 2004. The animals were observed 

moving back into the shore from the 

mouth of the Bay at 9 a.m. The usually 

pelagic animals milled in the shallow 

bay and were returned to deeper water 

with human assistance beginning at 9:30 

a.m. on July 4, 2004, and were out of 

sight by 10:30 a.m. 

Only one animal, a calf, was known 

to have died following this event. The 

animal was noted alive and alone in the 

Bay on the afternoon of July 4, 2004, 

and was found dead in the Bay the 

morning of July 5, 2004. A full 

necropsy, magnetic resonance imaging, 

and computerized tomography 

examination were performed on the calf 

to determine the manner and cause of 

death. The combination of imaging, 

necropsy and histological analyses 

found no evidence of infectious, 

internal traumatic, congenital, or toxic 

factors. Cause of death could not be 

definitively determined, but it is likely 

that maternal separation, poor 

nutritional condition, and dehydration 

contributed to the final demise of the 

animal. Although it is not known when 

the calf was separated from its mother, 

the animals’ movement into the Bay and 

subsequent milling and re-grouping may 

have contributed to the separation or 

lack of nursing, especially if the 

maternal bond was weak or this was an 

inexperienced mother with her first calf. 

Environmental factors, abiotic and 

biotic, were analyzed for any anomalous 

occurrences that would have 

contributed to the animals entering and 

remaining in Hanalei Bay. The Bay’s 

bathymetry is similar to many other 

sites within the Hawaiian Island chain 

and dissimilar to sites that have been 

associated with mass strandings in other 

parts of the U.S. The weather conditions 

appeared to be normal for that time of 

year with no fronts or other significant 

features noted. There was no evidence 

of unusual distribution, occurrence of 

predator or prey species, or unusual 

harmful algal blooms, although Mobley 

et al. (2007) suggested that the full moon 

cycle that occurred at that time may 

have influenced a run of squid into the 

Bay. Weather patterns and bathymetry 

that have been associated with mass 

strandings elsewhere were not found to 

occur in this instance. 

The Hanalei event was spatially and 

temporally correlated with RIMPAC. 

Official sonar training and tracking 

exercises in the Pacific Missile Range 

Facility (PMRF) warning area did not 

commence until approximately 8 a.m. 

on July 3 and were thus ruled out as a 

possible trigger for the initial movement 

into the Bay. However, six naval surface 

vessels transiting to the operational area 

on July 2 intermittently transmitted 

active sonar (for approximately nine 

hours total from 1:15 p.m. to 12:30 a.m.) 

as they approached from the south. The 

potential for these transmissions to have 

triggered the whales’ movement into 

Hanalei Bay was investigated. Analyses 

with the information available indicated 

that animals to the south and east of 

Kaua’i could have detected active sonar 

transmissions on July 2, and reached 

Hanalei Bay on or before 7 a.m. on July 

3. However, data limitations regarding 

the position of the whales prior to their 

arrival in the Bay, the magnitude of 

sonar exposure, behavioral responses of 

melon-headed whales to acoustic 

stimuli, and other possible relevant 

factors preclude a conclusive finding 

regarding the role of sonar in triggering 

this event. Propagation modeling 

suggests that transmissions from sonar 

use during the July 3 exercise in the 


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PMRF warning area may have been 

detectable at the mouth of the Bay. If the 

animals responded negatively to these 

signals, it may have contributed to their 

continued presence in the Bay. The U.S. 

Navy ceased all active sonar 

transmissions during exercises in this 

range on the afternoon of July 3. 

Subsequent to the cessation of sonar 

use, the animals were herded out of the 

Bay. 

While causation of this stranding 

event may never be unequivocally 

determined, NMFS consider the active 

sonar transmissions of July 2–3, 2004, a 

plausible, if not likely, contributing 

factor in what may have been a 

confluence of events. This conclusion is 

based on the following: (1) The 

evidently anomalous nature of the 

stranding; (2) its close spatiotemporal 

correlation with wide-scale, sustained 

use of sonar systems previously 

associated with stranding of deep-diving 

marine mammals; (3) the directed 

movement of two groups of transmitting 

vessels toward the southeast and 

southwest coast of Kauai; (4) the results 

of acoustic propagation modeling and 

an analysis of possible animal transit 

times to the Bay; and (5) the absence of 

any other compelling causative 

explanation. The initiation and 

persistence of this event may have 

resulted from an interaction of 

biological and physical factors. The 

biological factors may have included the 

presence of an apparently uncommon, 

deep-diving cetacean species (and 

possibly an offshore, non-resident 

group), social interactions among the 

animals before or after they entered the 

Bay, and/or unknown predator or prey 

conditions. The physical factors may 

have included the presence of nearby 

deep water, multiple vessels transiting 

in a directed manner while transmitting 

active sonar over a sustained period, the 

presence of surface sound ducting 

conditions, and/or intermittent and 

random human interactions while the 

animals were in the Bay. 

A separate event involving melonheaded whales and rough-toothed 

dolphins took place over the same 

period of time in the Northern Mariana 

Islands (Jefferson et al., 2006), which is 

several thousand miles from Hawaii. 

Some 500 to 700 melon-headed whales 

came into Sasanhaya Bay on July 4, 

2004, near the island of Rota and then 

left of their own accord after 5.5 hours; 

no known active sonar transmissions 

occurred in the vicinity of that event. 

The Rota incident led to scientific 

debate regarding what, if any, 

relationship the event had to the 

simultaneous events in Hawaii and 

whether they might be related by some 

common factor (e.g., there was a full 

moon on July 2, 2004, as well as during 

other melon-headed whale strandings 

and nearshore aggregations (Brownell et 

al., 2009; Lignon et al., 2007; Mobley et 

al., 2007). Brownell et al. (2009) 

compared the two incidents, along with 

one other stranding incident at Nuka 

Hiva in French Polynesia and normal 

resting behaviors observed at Palmyra 

Island, in regard to physical features in 

the areas, melon-headed whale 

behavior, and lunar cycles. Brownell et 

al., (2009) concluded that the rapid 

entry of the whales into Hanalei Bay, 

their movement into very shallow water 

far from the 100-m contour, their 

milling behavior (typical pre-stranding 

behavior), and their reluctance to leave 

the bay constituted an unusual event 

that was not similar to the events that 

occurred at Rota (but was similar to the 

events at Palmyra), which appear to be 

similar to observations of melon-headed 

whales resting normally at Palmyra 

Island. Additionally, there was no 

correlation between lunar cycle and the 

types of behaviors observed in the 

Brownell et al. (2009) examples. 

Spain (2006) 

The Spanish Cetacean Society 

reported an atypical mass stranding of 

four beaked whales that occurred 

January 26, 2006, on the southeast coast 

of Spain, near Mojacar (Gulf of Vera) in 

the Western Mediterranean Sea. 

According to the report, two of the 

whales were discovered the evening of 

January 26 and were found to be still 

alive. Two other whales were 

discovered during the day on January 

27, but had already died. The first three 

animals were located near the town of 

Mojacar and the fourth animal was 

found dead, a few kilometers north of 

the first three animals. From January 

25–26, 2006, Standing NATO Response 

Force Maritime Group Two (five of 

seven ships including one U.S. ship 

under NATO Operational Control) had 

conducted active sonar training against 

a Spanish submarine within 50 nmi (93 

km) of the stranding site. 

Veterinary pathologists necropsied 

the two male and two female Cuvier’s 

beaked whales. According to the 

pathologists, the most likely primary 

cause of this type of beaked whale mass 

stranding event was anthropogenic 

acoustic activities, most probably antisubmarine MFAS used during the 

military naval exercises. However, no 

positive acoustic link was established as 

a direct cause of the stranding. Even 

though no causal link can be made 

between the stranding event and naval 

exercises, certain conditions may have 

existed in the exercise area that, in their 

aggregate, may have contributed to the 

marine mammal strandings (Freitas, 

2004): Exercises were conducted in 

areas of at least 547 fathoms (1,000 m) 

depth near a shoreline where there is a 

rapid change in bathymetry on the order 

of 547 to 3,281 fathoms (1,000 to 6,000 

m) occurring across a relatively short 

horizontal distance (Freitas, 2004); 

multiple ships (in this instance, five) 

were operating MFAS in the same area 

over extended periods of time (in this 

case, 20 hours) in close proximity; and 

exercises took place in an area 

surrounded by landmasses, or in an 

embayment. Exercises involving 

multiple ships employing MFAS near 

land may have produced sound directed 

towards a channel or embayment that 

may have cut off the lines of egress for 

the affected marine mammals (Freitas, 

2004). 

Behaviorally Mediated Responses to 

MFAS That May Lead to Stranding 

Although the confluence of Navy 

MFAS with the other contributory 

factors noted in the report was 

identified as the cause of the 2000 

Bahamas stranding event, the specific 

mechanisms that led to that stranding 

(or the others) are not understood, and 

there is uncertainty regarding the 

ordering of effects that led to the 

stranding. It is unclear whether beaked 

whales were directly injured by sound 

(e.g., acoustically mediated bubble 

growth, as addressed above) prior to 

stranding or whether a behavioral 

response to sound occurred that 

ultimately caused the beaked whales to 

be injured and strand. 

Although causal relationships 

between beaked whale stranding events 

and active sonar remain unknown, 

several authors have hypothesized that 

stranding events involving these species 

in the Bahamas and Canary Islands may 

have been triggered when the whales 

changed their dive behavior in a startled 

response to exposure to active sonar or 

to further avoid exposure (Cox et al., 

2006; Rommel et al., 2006). These 

authors proposed three mechanisms by 

which the behavioral responses of 

beaked whales upon being exposed to 

active sonar might result in a stranding 

event. These include the following: Gas 

bubble formation caused by excessively 

fast surfacing; remaining at the surface 

too long when tissues are supersaturated 

with nitrogen; or diving prematurely 

when extended time at the surface is 

necessary to eliminate excess nitrogen. 

More specifically, beaked whales that 

occur in deep waters that are in close 

proximity to shallow waters (for 

example, the ‘‘canyon areas’’ that are 

cited in the Bahamas stranding event; 


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see D’Spain and D’Amico, 2006), may 

respond to active sonar by swimming 

into shallow waters to avoid further 

exposures and strand if they were not 

able to swim back to deeper waters. 

Second, beaked whales exposed to 

active sonar might alter their dive 

behavior. Changes in their dive behavior 

might cause them to remain at the 

surface or at depth for extended periods 

of time which could lead to hypoxia 

directly by increasing their oxygen 

demands or indirectly by increasing 

their energy expenditures (to remain at 

depth) and increase their oxygen 

demands as a result. If beaked whales 

are at depth when they detect a ping 

from an active sonar transmission and 

change their dive profile, this could lead 

to the formation of significant gas 

bubbles, which could damage multiple 

organs or interfere with normal 

physiological function (Cox et al., 2006; 

Rommel et al., 2006; Zimmer and 

Tyack, 2007). Baird et al. (2005) found 

that slow ascent rates from deep dives 

and long periods of time spent within 

50 m of the surface were typical for both 

Cuvier’s and Blainville’s beaked whales, 

the two species involved in mass 

strandings related to naval sonar. These 

two behavioral mechanisms may be 

necessary to purge excessive dissolved 

nitrogen concentrated in their tissues 

during their frequent long dives (Baird 

et al., 2005). Baird et al. (2005) further 

suggests that abnormally rapid ascents 

or premature dives in response to highintensity sonar could indirectly result in 

physical harm to the beaked whales, 

through the mechanisms described 

above (gas bubble formation or nonelimination of excess nitrogen). 

Because many species of marine 

mammals make repetitive and 

prolonged dives to great depths, it has 

long been assumed that marine 

mammals have evolved physiological 

mechanisms to protect against the 

effects of rapid and repeated 

decompressions. Although several 

investigators have identified 

physiological adaptations that may 

protect marine mammals against 

nitrogen gas supersaturation (alveolar 

collapse and elective circulation; 

Kooyman et al., 1972; Ridgway and 

Howard, 1979), Ridgway and Howard 

(1979) reported that bottlenose dolphins 

that were trained to dive repeatedly had 

muscle tissues that were substantially 

supersaturated with nitrogen gas. 

Houser et al. (2001) used these data to 

model the accumulation of nitrogen gas 

within the muscle tissue of other marine 

mammal species and concluded that 

cetaceans that dive deep and have slow 

ascent or descent speeds would have 

tissues that are more supersaturated 

with nitrogen gas than other marine 

mammals. Based on these data, Cox et 

al. (2006) hypothesized that a critical 

dive sequence might make beaked 

whales more prone to stranding in 

response to acoustic exposures. The 

sequence began with (1) very deep (to 

depths as deep as 2 km) and long (as 

long as 90 minutes) foraging dives; (2) 

relatively slow, controlled ascents; and 

(3) a series of ‘‘bounce’’ dives between 

100 and 400 m in depth (also see 

Zimmer and Tyack, 2007). They 

concluded that acoustic exposures that 

disrupted any part of this dive sequence 

(for example, causing beaked whales to 

spend more time at surface without the 

bounce dives that are necessary to 

recover from the deep dive) could 

produce excessive levels of nitrogen 

supersaturation in their tissues, leading 

to gas bubble and emboli formation that 

produces pathologies similar to 

decompression sickness. 

Zimmer and Tyack (2007) modeled 

nitrogen tension and bubble growth in 

several tissue compartments for several 

hypothetical dive profiles and 

concluded that repetitive shallow dives 

(defined as a dive where depth does not 

exceed the depth of alveolar collapse, 

approximately 72 m for Ziphius), 

perhaps as a consequence of an 

extended avoidance reaction to sonar 

sound, could pose a risk for 

decompression sickness and that this 

risk should increase with the duration 

of the response. Their models also 

suggested that unrealistically rapid rates 

of ascent from normal dive behaviors 

are unlikely to result in supersaturation 

to the extent that bubble formation 

would be expected. Tyack et al. (2006) 

suggested that emboli observed in 

animals exposed to mid-frequency range 

sonar (Jepson et al., 2003; Fernandez et 

al., 2005; Ferna ́ndez et al., 2012) could 

stem from a behavioral response that 

involves repeated dives shallower than 

the depth of lung collapse. Given that 

nitrogen gas accumulation is a passive 

process (i.e., nitrogen is metabolically 

inert), a bottlenose dolphin was trained 

to repetitively dive a profile predicted to 

elevate nitrogen saturation to the point 

that nitrogen bubble formation was 

predicted to occur. However, inspection 

of the vascular system of the dolphin via 

ultrasound did not demonstrate the 

formation of asymptomatic nitrogen gas 

bubbles (Houser et al., 2007). Baird et al. 

(2008), in a beaked whale tagging study 

off Hawaii, showed that deep dives are 

equally common during day or night, 

but ‘‘bounce dives’’ are typically a 

daytime behavior, possibly associated 

with visual predator avoidance. This 

may indicate that ‘‘bounce dives’’ are 

associated with something other than 

behavioral regulation of dissolved 

nitrogen levels, which would be 

necessary day and night. 

If marine mammals respond to a Navy 

vessel that is transmitting active sonar 

in the same way that they might 

respond to a predator, their probability 

of flight responses could increase when 

they perceive that Navy vessels are 

approaching them directly, because a 

direct approach may convey detection 

and intent to capture (Burger and 

Gochfeld, 1981, 1990; Cooper, 1997, 

1998). The probability of flight 

responses could also increase as 

received levels of active sonar increase 

(and the ship is, therefore, closer) and 

as ship speeds increase (that is, as 

approach speeds increase). For example, 

the probability of flight responses in 

Dall’s sheep (Ovis dalli dalli) (Frid 

2001a, b), ringed seals (Phoca hispida) 

(Born et al., 1999), Pacific brant (Branta 

bernic nigricans) and Canada geese (B. 

canadensis) increased as a helicopter or 

fixed-wing aircraft approached groups 

of these animals more directly (Ward et 

al., 1999). Bald eagles (Haliaeetus 

leucocephalus) perched on trees 

alongside a river were also more likely 

to flee from a paddle raft when their 

perches were closer to the river or were 

closer to the ground (Steidl and 

Anthony, 1996). 

Despite the many theories involving 

bubble formation (both as a direct cause 

of injury (see Acoustically Mediated 

Bubble Growth Section) and an indirect 

cause of stranding (See Behaviorally 

Mediated Bubble Growth Section), 

Southall et al. (2007) summarizes that 

there is either scientific disagreement or 

a lack of information regarding each of 

the following important points: (1) 

Received acoustical exposure conditions 

for animals involved in stranding 

events; (2) pathological interpretation of 

observed lesions in stranded marine 

mammals; (3) acoustic exposure 

conditions required to induce such 

physical trauma directly; (4) whether 

noise exposure may cause behavioral 

reactions (such as atypical diving 

behavior) that secondarily cause bubble 

formation and tissue damage; and (5) 

the extent the post mortem artifacts 

introduced by decomposition before 

sampling, handling, freezing, or 

necropsy procedures affect 

interpretation of observed lesions. 

Strandings Along Southern California 

and Hawaii 

Stranding events, specifically UMEs 

that occurred along Southern California 

or Hawaii (inclusive of the HSTT Study 


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Area) were previously discussed in the 

Description of Marine Mammals section. 

Data were gathered from stranding 

networks that operate within and 

adjacent to the HSTT Study Area and 

reviewed in an attempt to better 

understand the frequency that marine 

mammal strandings occur and what 

major causes of strandings (both humanrelated and natural) exist in areas 

around the HSTT Study Area (NMFS, 

2015a). From 2010 through 2014, there 

were 314 cetacean and phocid 

strandings reported in Hawaii, an 

annual average of 63 strandings per 

year. Twenty-seven species stranded in 

this region. The most common species 

reported include the Hawaiian monk 

seal, humpback whale, sperm whale, 

striped and spinner dolphin. Although 

many marine mammals likely strand 

due to natural or anthropogenic causes, 

the majority of reported type of 

occurrences in marine mammal 

strandings in the HSTT Study Area 

include fisheries interactions, 

entanglement, vessel strike and 

predation. Bradford and Lyman (2015) 

address overall threats from human 

activities and industries on stocks in 

Hawaii. 

In 2004, a mass out-of-habitat 

aggregation of melon-headed whales 

occurred in Hanalei Bay (see discussion 

above under ‘‘Strandings Associated 

with Active Sonar’’). It is speculated 

that sonar operated during a major 

training exercise may be related to the 

incident. Upon further investigation, 

sonar was only considered as a 

plausible, but not sole, contributing 

factor among many factors in the event. 

The Hanalei Bay incident does not share 

the characteristics observed with other 

mass strandings of whales coincident 

with sonar activity (e.g., specific 

traumas, species composition, etc.) 

(Southall et al., 2006; U.S. Navy Marine 

Mammal Program & Space and Naval 

Warfare Systems Command Center 

Pacific, 2017). Additional information 

on this event is available in the Navy’s 

Technical Report on Marine Mammal 

Strandings Associated with U.S. Navy 

Sonar Activities (U.S. Navy Marine 

Mammal Program & Space and Naval 

Warfare Systems Command Center 

Pacific, 2017). In addition, on October 

31, 2017, at least five pilot whales livestranded in Nawiliwili Harbor on Kauai. 

NMFS has yet to determine a cause for 

that stranding, but Navy activities can 

be dismissed from consideration given 

there were no Navy training or testing 

stressors present in the area before or 

during the stranding (National Marine 

Fisheries Service, 2017b). 

Records for strandings in San Diego 

County (covering the shoreline for the 

Southern California portion of the HSTT 

Study Area) indicate that there were 143 

cetacean and 1,235 pinniped strandings 

between 2010 and 2014, an annual 

average of about 29 and 247 per year, 

respectively. A total of 16 different 

species have been reported as stranded 

within this time frame. The majority of 

species reported include long-beaked 

common dolphins and California sea 

lions, but there were also reports of 

pacific white-sided, bottlenose and 

Risso’s dolphins, gray, humpback, and 

fin whales, harbor seals and Northern 

elephant seals (National Marine 

Fisheries Service, 2015b, 2016a). 

However, stranded marine mammals are 

reported along the entire western coast 

of the United States each year. Within 

the same timeframe, there were 714 

cetacean and 11,132 pinniped 

strandings reported outside of the Study 

Area, an annual average of about 142 

and 2,226 respectively. Species that 

strand along the entire west coast are 

similar to those that typically strand 

within the Study Area with additional 

reports of harbor porpoise, Dall’s 

porpoise, Steller sea lions, and various 

fur seals. The most common reported 

type of occurrence in stranded marine 

mammals in this region include fishery 

interactions, illness, predation, and 

vessel strikes (NMFS, 2016a). It is 

important to note that the mass 

stranding of pinnipeds along the west 

coast considered part of a NMFS 

declared UME are still being evaluated. 

The likely cause of this event is the lack 

of available prey near rookeries due to 

warming ocean temperatures (NOAA, 

2016a). Carretta et al. (2013b; 2016b) 

provide additional information and data 

on the threats from human-related 

activities and the potential causes of 

strandings for the U.S. Pacific coast 

marine mammal stocks. 

Potential Effects of Vessel Strike 

Vessel collisions with marine 

mammals, also referred to as vessel 

strikes or ship strikes, can result in 

death or serious injury of the animal. 

Wounds resulting from ship strike may 

include massive trauma, hemorrhaging, 

broken bones, or propeller lacerations 

(Knowlton and Kraus, 2001). An animal 

at the surface could be struck directly by 

a vessel, a surfacing animal could hit 

the bottom of a vessel, or an animal just 

below the surface could be cut by a 

vessel’s propeller. Superficial strikes 

may not kill or result in the death of the 

animal. Lethal interactions are typically 

associated with large whales, which are 

occasionally found draped across the 

bulbous bow of large commercial ships 

upon arrival in port. Although smaller 

cetaceans are more maneuverable in 

relation to large vessels than are large 

whales, they may also be susceptible to 

strike. The severity of injuries typically 

depends on the size and speed of the 

vessel (Knowlton and Kraus, 2001; Laist 

et al., 2001; Vanderlaan and Taggart, 

2007; Conn and Silber, 2013). Impact 

forces increase with speed, as does the 

probability of a strike at a given distance 

(Silber et al., 2010; Gende et al., 2011). 

The most vulnerable marine mammals 

are those that spend extended periods of 

time at the surface in order to restore 

oxygen levels within their tissues after 

deep dives (e.g., the sperm whale). In 

addition, some baleen whales, seem 

generally unresponsive to vessel sound, 

making them more susceptible to vessel 

collisions (Nowacek et al., 2004). These 

species are primarily large, slow moving 

whales. Marine mammal responses to 

vessels may include avoidance and 

changes in dive pattern (NRC, 2003). 

An examination of all known ship 

strikes from all shipping sources 

(civilian and military) indicates vessel 

speed is a principal factor in whether a 

vessel strike results in death or serious 

injury (Knowlton and Kraus, 2001; Laist 

et al., 2001; Jensen and Silber, 2003; 

Pace and Silber, 2005; Vanderlaan and 

Taggart, 2007). In assessing records in 

which vessel speed was known, Laist et 

al. (2001) found a direct relationship 

between the occurrence of a whale 

strike and the speed of the vessel 

involved in the collision. The authors 

concluded that most deaths occurred 

when a vessel was traveling in excess of 

13 kn. 

Jensen and Silber (2003) detailed 292 

records of known or probable ship 

strikes of all large whale species from 

1975 to 2002. Of these, vessel speed at 

the time of collision was reported for 58 

cases. Of these 58 cases, 39 (or 67 

percent) resulted in serious injury or 

death (19 of those resulted in serious 

injury as determined by blood in the 

water, propeller gashes or severed 

tailstock, and fractured skull, jaw, 

vertebrae, hemorrhaging, massive 

bruising or other injuries noted during 

necropsy and 20 resulted in death). 

Operating speeds of vessels that struck 

various species of large whales ranged 

from 2 to 51 kn. The majority (79 

percent) of these strikes occurred at 

speeds of 13 kn or greater. The average 

speed that resulted in serious injury or 

death was 18.6 kn. Pace and Silber 

(2005) found that the probability of 

death or serious injury increased rapidly 

with increasing vessel speed. 

Specifically, the predicted probability of 

serious injury or death increased from 

45 to 75 percent as vessel speed 

increased from 10 to 14 kn, and 

exceeded 90 percent at 17 kn. Higher 


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speeds during collisions result in greater 

force of impact and also appear to 

increase the chance of severe injuries or 

death. While modeling studies have 

suggested that hydrodynamic forces 

pulling whales toward the vessel hull 

increase with increasing speed (Clyne, 

1999; Knowlton et al., 1995), this is 

inconsistent with Silber et al. (2010), 

which demonstrated that there is no 

such relationship (i.e., hydrodynamic 

forces are independent of speed). 

In a separate study, Vanderlaan and 

Taggart (2007) analyzed the probability 

of lethal mortality of large whales at a 

given speed, showing that the greatest 

rate of change in the probability of a 

lethal injury to a large whale as a 

function of vessel speed occurs between 

8.6 and 15 kn. The chances of a lethal 

injury decline from approximately 80 

percent at 15 kn to approximately 20 

percent at 8.6 kn. At speeds below 11.8 

kn, the chances of lethal injury drop 

below 50 percent, while the probability 

asymptotically increases toward 100 

percent above 15 kn. 

The Jensen and Silber (2003) report 

notes that the database represents a 

minimum number of collisions, because 

the vast majority probably goes 

undetected or unreported. In contrast, 

Navy vessels are likely to detect any 

strike that does occur because of the 

required personnel training and 

lookouts (as described in the Proposed 

Mitigation Measures section), and they 

are required to report all ship strikes 

involving marine mammals. Overall, the 

percentage of Navy traffic relative to 

overall large shipping traffic are very 

small (on the order of two percent) and 

therefore represent a correspondingly 

smaller threat of potential ship strikes 

when compared to commercial 

shipping. 

In the SOCAL portion of the HSTT 

Study Area, the Navy has struck a total 

of 16 marine mammals in the 20-year 

period from 1991 through 2010 for an 

average of one per year. Of the 16 Navy 

vessel strikes over the 20-year period in 

SOCAL, there were seven mortalities 

and nine injuries reported. The vessel 

struck species include: Two mortalities 

and eight injuries of unknown species, 

three mortalities of gray whales (one in 

1993 and two in 1998), one mortality of 

a blue whale in 2004, and one morality 

and one injury of fin whales in 2009. 

In the HRC portion of the HSTT Study 

Area, the Navy struck a total of five 

marine mammals in the 20-year period 

from 1991 through 2010, for an average 

of zero to one per year. Of the five Navy 

vessel strikes over the 20-year period in 

the HRC, all were reported as injuries. 

The vessel struck species include: one 

humpback whale in 1998, one unknown 

species and one humpback whale in 

2003, one sperm whale in 2007, and an 

unknown species in 2008. No more than 

two whales were struck by Navy vessels 

in any given year in the HRC portion of 

the HSTT within the last 20 years. There 

was only one 12-month period in 20 

years in the HRC when two whales were 

struck in a single year (2003). 

Overall, there have been zero 

documented vessel strikes associated 

with training and testing in the SOCAL 

and HRC portions of the HSTT Study 

Area since 2010 and 2008, respectively. 

Between 2007 and 2009, the Navy 

developed and distributed additional 

training, mitigation, and reporting tools 

to Navy operators to improve marine 

mammal protection and to ensure 

compliance with permit requirements. 

In 2009, the Navy implemented Marine 

Species Awareness Training designed to 

improve effectiveness of visual 

observation for marine resources 

including marine mammals. In 

subsequent years, the Navy issued 

refined policy guidance on ship strikes 

in order to collect the most accurate and 

detailed data possible in response to a 

possible incident (also see the 

Notification and Reporting Plan for this 

proposed rule). For over a decade, the 

Navy has implemented the Protective 

Measures Assessment Protocol software 

tool, which provides operators with 

notification of the required mitigation 

and a visual display of the planned 

training or testing activity location 

overlaid with relevant environmental 

data. 

Marine Mammal Habitat 

The Navy’s proposed training and 

testing activities could potentially affect 

marine mammal habitat through the 

introduction of impacts to the prey 

species of marine mammals, acoustic 

habitat (sound in the water column), 

water quality, and important habitat for 

marine mammals. Each of these 

components was considered in the 

HSTT DEIS/OEIS and was determined 

by the Navy to have no effect on marine 

mammal habitat. Based on the 

information below and the supporting 

information included in the HSTT 

DEIS/OEIS, NMFS has determined that 

the proposed training and training 

activities would not have adverse or 

long-term impacts on marine mammal 

habitat. 

Effects to Prey 

Sound may affect marine mammals 

through impacts on the abundance, 

behavior, or distribution of prey species 

(e.g., crustaceans, cephalopods, fish, 

zooplankton). Marine mammal prey 

varies by species, season, and location 

and, for some, is not well documented. 

Here, we describe studies regarding the 

effects of noise on known marine 

mammal prey. Fish 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). The most likely effects on fishes 

exposed to loud, intermittent, lowfrequency sounds are behavioral 

responses (i.e., flight or avoidance). 

Short duration, sharp sounds (such as 

pile driving or air guns) can cause overt 

or subtle changes in fish behavior and 

local distribution. The reaction of fish to 

acoustic sources depends on the 

physiological state of the fish, past 

exposures, motivation (e.g., feeding, 

spawning, migration), and other 

environmental factors. Key impacts to 

fishes may include behavioral 

responses, hearing damage, barotrauma 

(pressure-related injuries), and 

mortality. 

Fishes, like other vertebrates, have 

variety of different sensory systems to 

glean information from ocean around 

them (Astrup and Mohl, 1993; Astrup, 

1999; Braun and Grande, 2008; Carroll 

et al., 2017; Hawkins and Johnstone, 

1978; Ladich and Popper, 2004; Ladich 

and Schulz-Mirbach, 2016; Mann, 2016; 

Nedwell et al., 2004; Popper et al., 2003; 

Popper et al., 2005). 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) (terrestrial 

vertebrates generally only detect 

pressure). Most marine fishes primarily 

detect particle motion using the inner 

ear and lateral line system, while some 

fishes possess additional morphological 

adaptations or specializations that can 

enhance their sensitivity to sound 

pressure, such as a gas-filled swim 

bladder (Braun and Grande, 2008; 

Popper and Fay, 2011). 

Hearing capabilities vary considerably 

between different fish species with data 

only available for just over 100 species 

out of the 34,000 marine and freshwater 

fish species (Eschmeyer and Fong 2016). 

In order to better understand acoustic 

impacts on fishes, fish hearing groups 

are defined by species that possess a 

similar continuum of anatomical 

features which result in varying degrees 

of hearing sensitivity (Popper and 

Hastings, 2009a). There are four hearing 

groups defined for all fish species 

(modified from Popper et al., 2014) 

within this analysis and they include: 

Fishes without a swim bladder (e.g., 

flatfish, sharks, rays, etc.); fishes with a 


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swim bladder not involved in hearing 

(e.g., salmon, cod, pollock, etc.); fishes 

with a swim bladder involved in 

hearing (e.g., sardines, anchovy, herring, 

etc.); and fishes with a swim bladder 

involved in hearing and high-frequency 

hearing (e.g., shad and menhaden). Most 

marine mammal fish prey species would 

not be likely to perceive or hear Navy 

mid- or high-frequency sonars (see 

Figure 9–1 of the Navy’s rulemaking/ 

LOA application). Within Southern 

California, the Clupeiformes order of 

fish include the Pacific sardine 

(Clupeidae), and northern anchovy 

(Engraulidae), key forage fish in 

Southern California. While hearing 

studies have not been done on sardines 

and northern anchovies, it would not be 

unexpected for them to have hearing 

similarities to Pacific herring (up to 2– 

5 kHz) (Mann et al., 2005). Currently, 

less data are available to estimate the 

range of best sensitivity for fishes 

without a swim bladder. In terms of 

physiology, multiple scientific studies 

have documented a lack of mortality or 

physiological effects to fish from 

exposure to low- and mid-frequency 

sonar and other sounds (Halvorsen et 

al., 2012; J<rgensen et al., 2005; Juanes 

et al., 2017; Kane et al., 2010; 

Kvadsheim and Sevaldsen, 2005; 

Popper et al., 2007; Popper et al., 2016; 

Watwood et al., 2016). Techer et al. 

(2017) exposed carp in floating cages for 

up to 30 days to low-power 23 and 46 

kHz source without any significant 

physiological response. Other studies 

have documented either a lack of TTS 

in species whose hearing range cannot 

perceive Navy sonar, or for those 

species that could perceive sonar-like 

signals, any TTS experienced would be 

recoverable (Halvorsen et al., 2012; 

Ladich and Fay, 2013; Popper and 

Hastings, 2009a, 2009b; Popper et al., 

2014; Smith, 2016). Only fishes that 

have specializations that enable them to 

hear sounds above about 2,500 Hz (2.5 

kHz) such as herring (Halvorsen et al., 

2012; Mann et al., 2005; Mann, 2016; 

Popper et al., 2014) would have the 

potential to receive TTS or exhibit 

behavioral responses from exposure to 

mid-frequency sonar. In addition, any 

sonar induced TTS to fish whose 

hearing range could perceive sonar 

would only occur in the narrow 

spectrum of the source (e.g., 3.5 kHz) 

compared to the fish’s total hearing 

range (e.g., 0.01 kHz to 5 kHz). Overall, 

Navy sonar sources are much narrower 

in terms of source frequency compared 

to a given fish species full hearing range 

(see examples in Figure 9–1 of the 

Navy’s rulemaking/LOA application). 

In terms of behavioral responses, 

Juanes et al. (2017) discuss the potential 

for negative impacts from anthropogenic 

soundscapes on fish, but the author’s 

focus was on broader based sounds such 

as ship and boat noise sources. 

Watwood et al. (2016) also documented 

no behavioral responses by reef fish 

after exposure to mid-frequency active 

sonar. Doksaeter et al. (2009; 2012) 

reported no behavioral responses to 

mid-frequency naval sonar by Atlantic 

herring, specifically, no escape reactions 

(vertically or horizontally) observed in 

free swimming herring exposed to midfrequency sonar transmissions. Based on 

these results (Doksaeter et al., 2009; 

Doksaeter et al., 2012; Sivle et al., 2012), 

Sivle et al. (2014) created a model in 

order to report on the possible 

population-level effects on Atlantic 

herring from active naval sonar. The 

authors concluded that the use of naval 

sonar poses little risk to populations of 

herring regardless of season, even when 

the herring populations are aggregated 

and directly exposed to sonar. Finally, 

Bruintjes et al. (2016) commented that 

fish exposed to any short-term noise 

within their hearing range might 

initially startle, but would quickly 

return to normal behavior. 

The potential effects of air gun 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. Some studies 

have shown no or slight reaction to air 

gun sounds (e.g., Pena et al., 2013; 

Wardle et al., 2001; Jorgenson and 

Gyselman, 2009; Cott et al., 2012). More 

commonly, though, the impacts of noise 

on fish are temporary. Investigators 

reported significant, short-term declines 

in commercial fishing catch rate of 

gadid fishes during and for up to five 

days after survey operations, but the 

catch rate subsequently returned to 

normal (Engas et al., 1996; Engas and 

Lokkeborg, 2002); other studies have 

reported similar findings (Hassel et al., 

2004). However, even temporary effects 

to fish distribution patterns can impact 

their ability to carry out important lifehistory functions (Paxton et al., 2017). 

SPLs of sufficient strength have been 

known to cause injury to fish and fish 

mortality and, in some studies, fish 

auditory systems have been damaged by 

air gun noise (McCauley et al., 2003; 

Popper et al., 2005; Song et al., 2008). 

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. 

(2012a) showed that a TTS of 4–6 dB 

was recoverable within 24 hrs 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. No mortality occurred 

to fish in any of these studies. 

Occasional behavioral reactions to 

intermittent explosions and impulsive 

sound sources are unlikely to cause 

long-term consequences for individual 

fish or populations. Fish that experience 

hearing loss as a result of exposure to 

explosions and impulsive sound sources 

may have a reduced ability to detect 

relevant sounds such as predators, prey, 

or social vocalizations. However, PTS 

has not been known to occur in fishes 

and any hearing loss in fish may be as 

temporary as the timeframe required to 

repair or replace the sensory cells that 

were damaged or destroyed (Popper et 

al., 2005; Popper et al., 2014; Smith et 

al., 2006). It is not known if damage to 

auditory nerve fibers could occur, and if 

so, whether fibers would recover during 

this process. It is also possible for fish 

to be injured or killed by an explosion 

in the immediate vicinity of the surface 

from dropped or fired ordnance, or near 

the bottom from shallow water bottomplaced underwater mine warfare 

detonations. Physical effects from 

pressure waves generated by underwater 

sounds (e.g., underwater explosions) 

could potentially affect fish within 

proximity of training or testing 

activities. The shock wave from an 

underwater explosion is lethal to fish at 

close range, causing massive organ and 

tissue damage and internal bleeding 

(Keevin and Hempen, 1997). At greater 

distance from the detonation point, the 

extent of mortality or injury depends on 

a number of factors including fish size, 

body shape, orientation, and species 

(Keevin and Hempen, 1997; Wright, 

1982). At the same distance from the 

source, larger fish are generally less 

susceptible to death or injury, elongated 

forms that are round in cross-section are 

less at risk than deep-bodied forms, and 

fish oriented sideways to the blast suffer 

the greatest impact (Edds-Walton and 

Finneran, 2006; O’Keeffe, 1984; 

O’Keeffe and Young, 1984; Wiley et al., 

1981; Yelverton et al., 1975). Species 

with gas-filled organs are more 

susceptible to injury and mortality than 

those without them (Gaspin, 1975; 

Gaspin et al., 1976; Goertner et al., 

1994). Barotrauma injuries have been 

documented during controlled exposure 

to impact pile driving (an impulsive 

noise source, as are explosives and air 

guns) (Halvorsen et al., 2012b; Casper et 

al., 2013). For seismic surveys, the 

sound source is constantly moving, and 

most fish would likely avoid the sound 


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source prior to receiving sound of 

sufficient intensity to cause 

physiological or anatomical damage. 

Fish not killed or driven from a 

location by an explosion might change 

their behavior, feeding pattern, or 

distribution. Changes in behavior of fish 

have been observed as a result of sound 

produced by explosives, with effect 

intensified in areas of hard substrate 

(Wright, 1982). However, Navy 

explosive use avoids hard substrate to 

the best extent practical during 

underwater detonations, or deep-water 

surface detonations (distance from 

bottom). Stunning from pressure waves 

could also temporarily immobilize fish, 

making them more susceptible to 

predation. The abundances of various 

fish (and invertebrates) near the 

detonation point for explosives could be 

altered for a few hours before animals 

from surrounding areas repopulate the 

area. However, these populations would 

likely be replenished as waters near the 

detonation point are mixed with 

adjacent waters. Repeated exposure of 

individual fish to sounds from 

underwater explosions is not likely and 

are expected to be short-term and 

localized. Long-term consequences for 

fish populations would not be expected. 

Several studies have demonstrated that 

air gun 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). 

In conclusion, for fishes exposed to 

Navy sonar, there would be limited 

sonar use spread out in time and space 

across large offshore areas such that 

only small areas are actually ensonified 

(10’s of miles) compared to the total life 

history distribution of fish prey species. 

There would be no probability for 

mortality and physical injury from 

sonar, and for most species, no or little 

potential for hearing or behavioral 

effects, except to a few select fishes with 

hearing specializations (e.g., herring) 

that could perceive mid-frequency 

sonar. Training and testing exercises 

involving explosions are dispersed in 

space and time; therefore, repeated 

exposure of individual fishes are 

unlikely. Morality and injury effects to 

fishes from explosives would be 

localized around the area of a given inwater explosion, but only if individual 

fish and the explosive (and immediate 

pressure field) were co-located at the 

same time. Fishes deeper in the water 

column or on the bottom would not be 

affected by water surface explosions. 

Repeated exposure of individual fish to 

sound and energy from underwater 

explosions is not likely given fish 

movement patterns, especially 

schooling prey species. Most acoustic 

effects, if any, are expected to be shortterm and localized. Long-term 

consequences for fish populations 

including key prey species within the 

HSTT Study Area would not be 

expected. 

Invertebrates appear to be able to 

detect sounds (Pumphrey, 1950; Frings 

and Frings, 1967) and are most sensitive 

to low-frequency sounds (Packard et al., 

1990; Budelmann and Williamson, 

1994; Lovell et al., 2005; Mooney et al., 

2010). Data on response of invertebrates 

such as squid, another marine mammal 

prey species, to anthropogenic sound is 

more limited (de Soto, 2016; Sole et al., 

2017b). Data suggest that cephalopods 

are capable of sensing the particle 

motion of sounds and detect low 

frequencies up to 1–1.5 kHz, depending 

on the species, and so are likely to 

detect air gun noise (Kaifu et al., 2008; 

Hu et al., 2009; Mooney et al., 2010; 

Samson et al., 2014). Sole et al. (2017b) 

reported physiological injuries to 

cuttlefish in cages placed at-sea when 

exposed during a controlled exposure 

experiment to low-frequency sources 

(315 Hz, 139 to 142 dB re 1 mPa2 and 

400 Hz, 139 to 141 dB re 1 mPa2). 

Fewtrell and McCauley (2012) reported 

squids maintained in cages displayed 

startle responses and behavioral changes 

when exposed to seismic air gun sonar 

(136–162 re 1 mPa2·s). However, the 

sources Sole et al. (2017a) and Fewtrell 

and McCauley (2012) used are not 

similar and much lower than typical 

Navy sources within the HSTT Study 

Area. Nor do the studies address the 

issue of individual displacement 

outside of a zone of impact when 

exposed to sound. Cephalopods have a 

specialized sensory organ inside the 

head called a statocyst that may help an 

animal determine its position in space 

(orientation) and maintain balance 

(Budelmann, 1992). Packard et al. 

(1990) showed that cephalopods were 

sensitive to particle motion, not sound 

pressure, and Mooney et al. (2010) 

demonstrated that squid statocysts act 

as an accelerometer through which 

particle motion of the sound field can be 

detected. Auditory injuries (lesions 

occurring on the statocyst sensory hair 

cells) have been reported upon 

controlled exposure to low-frequency 

sounds, suggesting that cephalopods are 

particularly sensitive to low-frequency 

sound (Andre et al., 2011; Sole et al., 

2013). Behavioral responses, such as 

inking and jetting, have also been 

reported upon exposure to lowfrequency sound (McCauley et al., 

2000b; Samson et al., 2014). Squids, like 

most fish species, are likely more 

sensitive to low frequency sounds, and 

may not perceive mid- and highfrequency sonars such as Navy sonars. 

Cumulatively for squid as a prey 

species, individual and population 

impacts from exposure to Navy sonar 

and explosives, like fish, are not likely 

to be significant, and explosive impacts 

would be short-term and localized. 

Vessels and in-water devices do not 

normally collide with adult fish, most of 

which can detect and avoid them. 

Exposure of fishes to vessel strike 

stressors is limited to those fish groups 

that are large, slow-moving, and may 

occur near the surface, such as ocean 

sunfish, whale sharks, basking sharks, 

and manta rays. These species are 

distributed widely in offshore portions 

of the Study Area. Any isolated cases of 

a Navy vessel striking an individual 

could injure that individual, impacting 

the fitness of an individual fish. Vessel 

strikes would not pose a risk to most of 

the other marine fish groups, because 

many fish can detect and avoid vessel 

movements, making strikes rare and 

allowing the fish to return to their 

normal behavior after the ship or device 

passes. As a vessel approaches a fish, 

they could have a detectable behavioral 

or physiological response (e.g., 

swimming away and increased heart 

rate) as the passing vessel displaces 

them. However, such reactions are not 

expected to have lasting effects on the 

survival, growth, recruitment, or 

reproduction of these marine fish 

groups at the population level and 

therefore would not have an impact on 

marine mammals species as prey items. 

In addition to fish, prey sources such 

as marine invertebrates could 

potentially be impacted by sound 

stressors as a result of the proposed 

activities. However, most marine 

invertebrates’ ability to sense sounds is 

very limited. In most cases, marine 

invertebrates would not respond to 

impulsive and non-impulsive sounds, 

although they may detect and briefly 

respond to nearby low-frequency 

sounds. These short-term responses 

would likely be inconsequential to 

invertebrate populations. Impacts to 

benthic communities from impulsive 

sound generated by active acoustic 

sound sources are not well documented. 

(e.g., Andriguetto-Filho et al., 2005; 

Payne et al., 2007; 2008; Boudreau et al., 

2009). There are no published data that 

indicate whether temporary or 

permanent threshold shifts, auditory 

masking, or behavioral effects occur in 

benthic invertebrates (Hawkins et al., 

2014) and some studies showed no 


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short-term or long-term effects of air gun 

exposure (e.g., Andriguetto-Filho et al., 

2005; Payne et al., 2007; 2008; Boudreau 

et al., 2009). Exposure to air gun signals 

was found to significantly increase 

mortality in scallops, in addition to 

causing significant changes in 

behavioral patterns during exposure 

(Day et al., 2017). However, the authors 

state that the observed levels of 

mortality were not beyond naturally 

occurring rates. Explosions and pile 

driving could potentially kill or injure 

nearby marine invertebrates; however, 

mortality or long-term consequences for 

a few animals is unlikely to have 

measurable effects on overall stocks or 

populations. 

Vessels also have the potential to 

impact marine invertebrates by 

disturbing the water column or 

sediments, or directly striking 

organisms (Bishop, 2008). The propeller 

wash (water displaced by propellers 

used for propulsion) from vessel 

movement and water displaced from 

vessel hulls can potentially disturb 

marine invertebrates in the water 

column and is a likely cause of 

zooplankton mortality (Bickel et al., 

2011). The localized and short-term 

exposure to explosions or vessels could 

displace, injure, or kill zooplankton, 

invertebrate eggs or larvae, and macroinvertebrates. However, mortality or 

long-term consequences for a few 

animals is unlikely to have measurable 

effects on overall stocks or populations. 

There is little information concerning 

potential impacts of noise on 

zooplankton populations. However, one 

recent study (McCauley et al., 2017) 

investigated zooplankton abundance, 

diversity, and mortality before and after 

exposure to air gun noise, finding that 

the exposure resulted in significant 

depletion for more than half the taxa 

present and that there were two to three 

times more dead zooplankton after air 

gun exposure compared with controls 

for all taxa. The majority of taxa present 

were copepods and cladocerans; for 

these taxa, the range within which 

effects on abundance were detected was 

up to approximately 1.2 km. In order to 

have significant impacts on r-selected 

species such as plankton, the spatial or 

temporal scale of impact must be large 

in comparison with the ecosystem 

concerned (McCauley et al., 2017). 

Therefore, the large scale of effect 

observed here is of concern— 

particularly where repeated noise 

exposure is expected—and further study 

is warranted. 

Overall, the combined impacts of 

sound exposure, explosions, vessel 

strikes, and military expended materials 

resulting from the proposed activities 

would not be expected to have 

measurable effects on populations of 

marine mammal prey species. Prey 

species exposed to sound might move 

away from the sound source, experience 

TTS, experience masking of biologically 

relevant sounds, or show no obvious 

direct effects. Mortality from 

decompression injuries is possible in 

close proximity to a sound, but only 

limited data on mortality in response to 

air gun noise exposure are available 

(Hawkins et al., 2014). The most likely 

impacts for most prey species in a given 

area would be temporary avoidance of 

the area. Surveys using towed air gun 

arrays move through an area relatively 

quickly, limiting exposure to multiple 

impulsive sounds. In all cases, sound 

levels would return to ambient once a 

survey ends and the noise source is shut 

down and, when exposure to sound 

ends, behavioral and/or physiological 

responses are expected to end relatively 

quickly (McCauley et al., 2000b). The 

duration of fish avoidance of a given 

area after survey effort stops is 

unknown, but a rapid return to normal 

recruitment, distribution, and behavior 

is anticipated. While the potential for 

disruption of spawning aggregations or 

schools of important prey species can be 

meaningful on a local scale, the mobile 

and temporary nature of most surveys 

and the likelihood of temporary 

avoidance behavior suggest that impacts 

would be minor. Long-term 

consequences to marine invertebrate 

populations would not be expected as a 

result of exposure to sounds or vessels 

in the Study Area. Military expended 

materials resulting from training and 

testing activities could potentially result 

in minor long-term changes to benthic 

habitat. Military expended materials 

may be colonized over time by benthic 

organisms that prefer hard substrate and 

would provide structure that could 

attract some species of fish or 

invertebrates. 

Acoustic Habitat 

Acoustic habitat is the soundscape 

which encompasses all of the sound 

present in a particular location and 

time, as a whole when considered from 

the perspective of the animals 

experiencing it. Animals produce sound 

for, or listen for sounds produced by, 

conspecifics (communication during 

feeding, mating, and other social 

activities), other animals (finding prey 

or avoiding predators), and the physical 

environment (finding suitable habitats, 

navigating). Together, sounds made by 

animals and the geophysical 

environment (e.g., produced by 

earthquakes, lightning, wind, rain, 

waves) make up the natural 

contributions to the total acoustics of a 

place. These acoustic conditions, 

termed acoustic habitat, are one 

attribute of an animal’s total habitat. 

Soundscapes are also defined by, and 

acoustic habitat influenced by, the total 

contribution of anthropogenic sound. 

This may include incidental emissions 

from sources such as vessel traffic, may 

be intentionally introduced to the 

marine environment for data acquisition 

purposes (as in the use of air gun 

arrays), or for Navy training and testing 

purposes (as in the use of sonar and 

explosives and other acoustic sources). 

Anthropogenic noise varies widely in its 

frequency, content, duration, and 

loudness and these characteristics 

greatly influence the potential habitatmediated effects to marine mammals 

(please also see the previous discussion 

on ‘‘Masking’’), which may range from 

local effects for brief periods of time to 

chronic effects over large areas and for 

long durations. Depending on the extent 

of effects to habitat, animals may alter 

their communications signals (thereby 

potentially expending additional 

energy) or miss acoustic cues (either 

conspecific or adventitious). Problems 

arising from a failure to detect cues are 

more likely to occur when noise stimuli 

are chronic and overlap with 

biologically relevant cues used for 

communication, orientation, and 

predator/prey detection (Francis and 

Barber, 2013). For more detail on these 

concepts see, e.g., Barber et al., 2009; 

Pijanowski et al., 2011; Francis and 

Barber, 2013; Lillis et al., 2014. 

The term ‘‘listening area’’ refers to the 

region of ocean over which sources of 

sound can be detected by an animal at 

the center of the space. Loss of 

communication space concerns the area 

over which a specific animal signal, 

used to communicate with conspecifics 

in biologically-important contexts (e.g., 

foraging, mating), can be heard, in 

noisier relative to quieter conditions 

(Clark et al., 2009). Lost listening area 

concerns the more generalized 

contraction of the range over which 

animals would be able to detect a 

variety of signals of biological 

importance, including eavesdropping on 

predators and prey (Barber et al., 2009). 

Such metrics do not, in and of 

themselves, document fitness 

consequences for the marine animals 

that live in chronically noisy 

environments. Long-term populationlevel consequences mediated through 

changes in the ultimate survival and 

reproductive success of individuals are 

difficult to study, and particularly so 

underwater. However, it is increasingly 

well documented that aquatic species 

rely on qualities of natural acoustic 


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habitats, with researchers quantifying 

reduced detection of important 

ecological cues (e.g., Francis and Barber, 

2013; Slabbekoorn et al., 2010) as well 

as survivorship consequences in several 

species (e.g., Simpson et al., 2014; 

Nedelec et al., 2015). 

Sound produced from training and 

testing activities in the HSTT Study 

Area is temporary and transitory. The 

sounds produced during training and 

testing activities can be widely 

dispersed or concentrated in small areas 

for varying periods. Any anthropogenic 

noise attributed to training and testing 

activities in the HSTT Study Area 

would be temporary and the affected 

area would be expected to immediately 

return to the original state when these 

activities cease. 

Water Quality 

The HSTT DEIS/OEIS analyzed the 

potential effects on water quality from 

military expended materials. Training 

and testing activities may introduce 

water quality constituents into the water 

column. Based on the analysis of the 

HSTT DEIS/OEIS, military expended 

materials (e.g., undetonated explosive 

materials) would be released in 

quantities and at rates that would not 

result in a violation of any water quality 

standard or criteria. High-order 

explosions consume most of the 

explosive material, creating typical 

combustion products. For example, in 

the case of Royal Demolition Explosive, 

98 percent of the products are common 

seawater constituents and the remainder 

is rapidly diluted below threshold effect 

level. Explosion by-products associated 

with high order detonations present no 

secondary stressors to marine mammals 

through sediment or water. However, 

low order detonations and unexploded 

ordnance present elevated likelihood of 

impacts on marine mammals. 

Indirect effects of explosives and 

unexploded ordnance to marine 

mammals via sediment is possible in the 

immediate vicinity of the ordnance. 

Degradation products of Royal 

Demolition Explosive are not toxic to 

marine organisms at realistic exposure 

levels (Rosen and Lotufo, 2010). 

Relatively low solubility of most 

explosives and their degradation 

products means that concentrations of 

these contaminants in the marine 

environment are relatively low and 

readily diluted. Furthermore, while 

explosives and their degradation 

products were detectable in marine 

sediment approximately 6–12 in (0.15– 

0.3 m) away from degrading ordnance, 

the concentrations of these compounds 

were not statistically distinguishable 

from background beyond 3–6 ft (1–2 m) 

from the degrading ordnance. Taken 

together, it is possible that marine 

mammals could be exposed to 

degrading explosives, but it would be 

within a very small radius of the 

explosive (1–6 ft (0.3–2 m)). 

Equipment used by the Navy within 

the HSTT Study Area, including ships 

and other marine vessels, aircraft, and 

other equipment, are also potential 

sources of by-products. All equipment is 

properly maintained in accordance with 

applicable Navy or legal requirements. 

All such operating equipment meets 

Federal water quality standards, where 

applicable. 

Estimated Take of Marine Mammals 

This section indicates the number of 

takes that NMFS is proposing to 

authorize which is based on the amount 

of take that NMFS anticipates could or 

is likely to occur, depending on the type 

of take and the methods used to 

estimate it, as described in detail below. 

NMFS coordinated closely with the 

Navy in the development of their 

incidental take application, and with 

one exception, preliminarily agrees that 

the methods the Navy has put forth 

described herein to estimate take 

(including the model, thresholds, and 

density estimates), and the resulting 

numbers estimated for authorization, are 

appropriate and based on the best 

available science. 

Takes are predominantly in the form 

of harassment, but a small number of 

mortalities are also estimated. For a 

military readiness activity, the MMPA 

defines ‘‘harassment’’ as (i) Any act that 

injures or has the significant potential to 

injure a marine mammal or marine 

mammal stock in the wild (Level A 

Harassment); or (ii) Any act that 

disturbs or is likely to disturb a marine 

mammal or marine mammal stock in the 

wild by causing disruption of natural 

behavioral patterns, including, but not 

limited to, migration, surfacing, nursing, 

breeding, feeding, or sheltering, to a 

point where such behavioral patterns 

are abandoned or significantly altered 

(Level B Harassment). 

Authorized takes would primarily be 

in the form of Level B harassment, as 

use of the acoustic and explosive 

sources (i.e., sonar, air guns, pile 

driving, explosives) is likely to result in 

the disruption of natural behavioral 

patterns to a point where they are 

abandoned or significantly altered (as 

defined specifically at the beginning of 

this section, but referred to generally as 

behavioral disruption) or TTS for 

marine mammals. There is also the 

potential for Level A harassment, in the 

form of auditory injury and/or tissue 

damage (latter for explosives only) to 

result from exposure to the sound 

sources utilized in training and testing 

activities. Lastly, a limited number of 

serious injuries or mortalities could 

occur for California sea lion and shortbeaked common dolphin (10 mortalities 

total between the two species over the 

5-year period) from explosives, and no 

more than three serious injuries or 

mortalities total (over the five-year 

period) of large whales through vessel 

collisions. Although we analyze the 

impacts of these potential serious 

injuries or mortalities that are proposed 

for authorization, the proposed 

mitigation and monitoring measures are 

expected to minimize the likelihood 

(i.e., further lower the already low 

probability) that ship strike or these 

explosive exposures (and the associated 

serious injury or mortality) occur. 

Described in the most basic way, we 

estimate the amount and type of 

harassment by considering: (1) Acoustic 

thresholds above which NMFS believes 

the best available science indicates 

marine mammals will be behaviorally 

harassed (in this case, as defined in the 

military readiness definition included 

above) or incur some degree of 

temporary or permanent hearing 

impairment; (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) and the 

number of days during which activities 

might occur. Below, we describe these 

components in more detail and present 

the proposed take estimate. 

Acoustic Thresholds 

Using the best available science, and 

in coordination with the Navy, NMFS 

has established acoustic thresholds 

above which exposed marine mammals 

would reasonably be expected to 

experience a disruption in behavioral 

patterns to a point where they are 

abandoned or significantly altered, or to 

incur TTS (equated to Level B 

harassment) or PTS of some degree 

(equated to Level A harassment). 

Thresholds have also been developed to 

identify the pressure levels above which 

animals may incur different types of 

tissue damage from exposure to pressure 

waves from explosive detonation. 

Hearing Impairment (TTS/PTS and 

Tissue Damage and Mortality) 

Non-Impulsive and Impulsive 

NMFS’s Technical Guidance for 

Assessing the Effects of Anthropogenic 

Sound on Marine Mammal Hearing 

(Technical Guidance, 2016) identifies 

dual criteria to assess auditory injury 

(Level A harassment) to five different 


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marine mammal groups (based on 

hearing sensitivity) as a result of 

exposure to noise from two different 

types of sources (impulsive or nonimpulsive). The Technical Guidance 

also identifies criteria to predict TTS, 

which is not considered injury and falls 

into the Level B Harassment category. 

The Navy’s Specified Activities 

includes the use of non-impulsive 

(sonar, vibratory pile driving/removal) 

sources and impulsive (explosives, air 

guns, impact pile driving) sources. 

These thresholds (Tables 14–15) were 

developed by compiling and 

synthesizing the best available science 

and soliciting input multiple times from 

both the public and peer reviewers to 

inform the final product, and are 

provided in the table below. The 

references, analysis, and methodology 

used in the development of the 

thresholds are described in NMFS 2016 

Technical Guidance, which may be 

accessed at: http://www.nmfs.noaa.gov/ 

pr/acoustics/guidelines.htm. 

TABLE 14—ACOUSTIC THRESHOLDS IDENTIFYING THE ONSET OF TTS AND PTS FOR NON-IMPULSIVE SOUND SOURCES BY

FUNCTIONAL HEARING GROUPS

Functional hearing group 

Non-impulsive 

TTS 

threshold 

SEL 

(weighted) 

PTS 

threshold 

SEL 

(weighted) 

Low-Frequency Cetaceans ...................................................................................................................................... 179 199 

Mid-Frequency Cetaceans ....................................................................................................................................... 178 198 

High-Frequency Cetaceans ..................................................................................................................................... 153 173 

Phocid Pinnipeds (Underwater) ............................................................................................................................... 181 201 

Ottarid Pinnipeds (Underwater) ............................................................................................................................... 199 219 

Note: SEL thresholds in dB re 1 μPa2s. 

Based on the best available science, 

the Navy (in coordination with NMFS) 

used the acoustic and pressure 

thresholds indicated in Table 15 to 

predict the onset of TTS, PTS, tissue 

damage, and mortality for explosives 

(impulsive) and other impulsive sound 

sources. 

TABLE 15—ONSET OF TTS, PTS, TISSUE DAMAGE, AND MORTALITY THRESHOLDS FOR MARINE MAMMALS FOR

EXPLOSIVES AND OTHER IMPULSIVE SOURCES

Functional hearing group Species Weighted onset TTS Weighted onset PTS Mean onset slight 

GI tract injury 

Mean onset 

slight lung 

injury 

Mean onset 

mortality 

Low-frequency cetaceans ...... All mysticetes ........................ 168 dB SEL or 213 dB 

Peak SPL.

183 dB SEL or 219 dB 

Peak SPL.

237 dB Peak SPL Equation 1 .. Equation 2. 

Mid-frequency cetaceans ....... Most delphinids, medium and 

large toothed whales.

170 dB SEL or 224 dB 

Peak SPL.

185 dB SEL or 230 dB 

Peak SPL.

237 dB Peak SPL.

High-frequency cetaceans ..... Porpoises and Kogia spp ..... 140 dB SEL or 196 dB 

Peak SPL.

155 dB SEL or 202 dB 

Peak SPL.

237 dB Peak SPL.

Phocidae ................................ Harbor seal, Hawaiian monk 

seal, Northern elephant 

seal.

170 dB SEL or 212 dB 

Peak SPL.

185 dB SEL or 218 dB 

Peak SPL.

237 dB Peak SPL.

Otariidae ................................. California sea lion, Guadalupe fur seal, Northern fur 

seal.

188 dB SEL or 226 dB 

Peak SPL.

203 dB SEL or 232 dB 

Peak SPL.

237 dB Peak SPL.

Notes: 

Equation 1: 47.5M1/3 (1 + [DRm / 10.1])1/6 Pa-sec. 

Equation 2: 103M1/3 (1 + [DRm / 10.1])1/6 Pa-sec. 

M = mass of the animals in kg. 

DRm = depth of the receiver (animal) in meters. 

SPL = sound pressure level. 

Impulsive—Air Guns and Impact Pile 

Driving 

Impact pile driving produces 

impulsive noise; therefore, the criteria 

used to assess the onset of TTS and PTS 

are identical to those used for air guns, 

as well as explosives (see Table 15 

above) (see Hearing Loss from air guns 

in Section 6.4.3.1, Methods for 

Analyzing Impacts from air guns in the 

Navy’s rulemaking/LOA application). 

Refer to the Criteria and Thresholds for 

U.S. Navy Acoustic and Explosive 

Effects Analysis (Phase III) report (U.S. 

Department of the Navy, 2017c) for 

detailed information on how the criteria 

and thresholds were derived. 

Non-Impulsive—Sonar and Vibratory 

Pile Driving/Removal 

Vibratory pile removal (that will be 

used during the ELCAS) creates 

continuous non-impulsive noise at low 

source levels for a short duration. 

Therefore, the criteria used to assess the 

onset of TTS and PTS due to exposure 

to sonars (non-impulsive, see Table 14 

above) are also used to assess auditory 

impacts to marine mammals from 

vibratory pile driving (see Hearing Loss 

from Sonar and Other Transducers in 

Section 6.4.2.1, Methods for Analyzing 

Impacts from Sonars and Other 

Transducers in the Navy’s rulemaking/ 

LOA application). Refer to the Criteria 

and Thresholds for U.S. Navy Acoustic 

and Explosive Effects Analysis (Phase 

III) report (U.S. Department of the Navy, 

2017c) for detailed information on how 

the criteria and thresholds were derived. 

Non-auditory injury (i.e., other than 

PTS) and mortality from sonar and other 

transducers is so unlikely as to be 

discountable under normal conditions 

for the reasons explained in the 

Potential Effects of Specified Activities 

on Marine Mammals and Their Habitat 


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section under ‘‘Acoustically Mediated 

Bubble Growth and other Pressurerelated Injury’’ and is therefore not 

considered further in this analysis. 

Behavioral Harassment 

Marine mammal responses (some of 

which are considered disturbances that 

rise to the level of a take) to sound are 

highly variable and context specific 

(affected by differences in acoustic 

conditions, differences between species 

and populations; differences in gender, 

age, reproductive status, or social 

behavior; or other prior experience of 

the individuals), which means that there 

is support for alternative approaches for 

estimating behavioral harassment. 

Although the statutory definition of 

Level B harassment for military 

readiness activities requires that the 

natural behavior patterns of a marine 

mammal be significantly altered or 

abandoned in order to qualify as a take, 

the current state of science for 

determining those thresholds is still 

evolving and indefinite. In its analysis 

of impacts associated with sonar 

acoustic sources (which was 

coordinated with NMFS), the Navy 

proposes, and NMFS supports, an 

updated conservative approach that 

likely overestimates the number of takes 

by Level B harassment due to behavioral 

disturbance and response. Many of the 

responses estimated using the Navy’s 

quantitative analysis are most likely to 

be moderate severity (see Southall et al., 

2007 for behavior response severity 

scale). Moderate severity responses 

would be considered significant if they 

were sustained for a duration long 

enough that it caused an animal to be 

outside of normal variation in daily 

behavioral patterns in feeding, 

reproduction, resting, migration/ 

movement, or social cohesion. Many of 

the behavioral reactions predicted by 

the Navy’s quantitative analysis are only 

expected to exceed an animal’s 

behavioral threshold for a single 

exposure lasting several minutes. It is 

therefore likely that some of the 

exposures that are included in the 

estimated behavioral harassment takes 

would not actually constitute significant 

alterations or abandonment of natural 

behavior patterns. The Navy and NMFS 

have used the best available science to 

address the challenge of differentiating 

between behavioral reactions that rise to 

the level of a take and those that do not, 

but have erred on the side of caution 

where uncertainty exists (e.g., counting 

these lower duration reactions as take). 

This conservative choice likely results 

in some degree of overestimation of 

behavioral harassment take. Therefore, 

this analysis includes the maximum 

number of behavioral disturbances and 

responses that are reasonably possible to 

occur. 

Air Guns and Pile Driving 

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 (e.g., frequency, predictability, 

duty cycle), the environment (e.g., 

bathymetry), and the receiving animals 

(hearing, motivation, experience, 

demography, behavioral context) and 

can be difficult to predict (Southall et 

al., 2007, Ellison et al., 2011). Based on 

what the available science indicates and 

the practical need to use a threshold 

based on a factor that is both predictable 

and measurable for most activities, 

NMFS uses a generalized acoustic 

threshold based on received level to 

estimate the onset of behavioral 

harassment. NMFS predicts that marine 

mammals are likely to be behaviorally 

harassed in a manner we consider Level 

B harassment when exposed to 

underwater anthropogenic noise above 

received levels of 120 dB re 1 mPa (rms) 

for continuous (e.g., vibratory piledriving, drilling) and above 160 dB re 1 

mPa (rms) for non-explosive impulsive 

(e.g., seismic air guns) or intermittent 

(e.g., scientific sonar) sources. To 

estimate behavioral effects from air 

guns, the existing NMFS Level B 

harassment threshold of 160 dB re 1 mPa 

(rms) is used. The root mean square 

calculation for air guns is based on the 

duration defined by 90 percent of the 

cumulative energy in the impulse. 

The existing NMFS Level B 

harassment thresholds were also 

applied to estimate behavioral effects 

from impact and vibratory pile driving 

(Table 16). 

TABLE 16—PILE DRIVING LEVEL B 

THRESHOLDS USED IN THIS ANALYSIS TO PREDICT BEHAVIORAL RESPONSES FROM MARINE MAMMALS

Pile driving criteria (SPL, dB re 1 μPa) 

Level B disturbance threshold 

Underwater vibratory Underwater impact 

120 dB rms ............... 160 dB rms. 

Notes: Root mean square calculation for 

impact pile driving is based on the duration 

defined by 90 percent of the cumulative energy in the impulse. Root mean square for vibratory pile driving is calculated based on a 

representative time series long enough to capture the variation in levels, usually on the 

order of a few seconds. 

dB: decibel; dB re 1 μPa: decibel referenced 

to 1 micropascal; rms: root mean square. 

Sonar 

As noted, the Navy coordinated with 

NMFS to propose behavioral harassment 

thresholds specific to their military 

readiness activities utilizing active 

sonar. Behavioral response criteria are 

used to estimate the number of animals 

that may exhibit a behavioral response 

to sonar and other transducers. The way 

the criteria were derived is discussed in 

detail in the Criteria and Thresholds for 

U.S. Navy Acoustic and Explosive 

Effects Analysis (Phase III) report (U.S. 

Department of the Navy, 2017c). 

Developing the new behavioral criteria 

involved multiple steps. All peerreviewed published behavioral response 

studies conducted both in the field and 

on captive animals were examined in 

order to understand the breadth of 

behavioral responses of marine 

mammals to sonar and other 

transducers. NMFS supported the 

development of this methodology and 

considered it appropriate to calculate 

take and support the preliminary 

determinations made in the proposed 

rule. 

In the Navy acoustic impact analyses 

during Phase II, the likelihood of 

behavioral effects to sonar and other 

transducers was based on a probabilistic 

function (termed a behavioral response 

function—BRF), that related the 

likelihood (i.e., probability) of a 

behavioral response to the received SPL. 

The BRF was used to estimate the 

percentage of an exposed population 

that is likely to exhibit altered behaviors 

or behavioral disturbance at a given 

received SPL. This BRF relied on the 

assumption that sound poses a 

negligible risk to marine mammals if 

they are exposed to SPL below a certain 

‘‘basement’’ value. Above the basement 

exposure SPL, the probability of a 

response increased with increasing SPL. 

Two BRFs were used in Navy acoustic 

impact analyses: BRF1 for mysticetes 

and BRF2 for other species. BRFs were 

not used for beaked whales during 

Phase II analyses. Instead, step 

functions at SPLs of 120 dB re 1 mPa and 

140 dB re 1 mPa were used for harbor 

porpoises and beaked whales, 

respectively, as thresholds to predict 

behavioral disturbance. It should be 

noted that in the HSTT Study Area there 

are no harbor porpoise. 

Developing the new behavioral 

criteria for Phase III involved multiple 

steps: All available behavioral response 

studies conducted both in the field and 

on captive animals were examined in 

order to better understand the breadth of 

behavioral responses of marine 

mammals to sonar and other 

transducers. Marine mammal species 


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were placed into behavioral criteria 

groups based on their known or 

suspected behavioral sensitivities to 

sound. In most cases these divisions 

were driven by taxonomic 

classifications (e.g., mysticetes, 

pinnipeds). The data from the 

behavioral studies were analyzed by 

looking for significant responses, or lack 

thereof, for each experimental session. 

The Navy used cutoff distances 

beyond which the potential of 

significant behavioral responses (and 

therefore Level B harassment) is 

considered to be unlikely (see Table 16 

below). For animals within the cutoff 

distance, a behavioral response function 

based on a received SPL as presented in 

Section 3.1.0 of the Navy’s rulemaking/ 

LOA application was used to predict the 

probability of a potential significant 

behavioral response. For training and 

testing events that contain multiple 

platforms or tactical sonar sources that 

exceed 215 dB re 1 mPa @1 1 m, this 

cutoff distance is substantially increased 

(i.e., doubled) from values derived from 

the literature. The use of multiple 

platforms and intense sound sources are 

factors that probably increase 

responsiveness in marine mammals 

overall. There are currently few 

behavioral observations under these 

circumstances; therefore, the Navy 

conservatively predicted significant 

behavioral responses at farther ranges as 

shown in Table 17, versus less intense 

events. 

TABLE 17—CUTOFF DISTANCES FOR MODERATE SOURCE LEVEL, SINGLE PLATFORM TRAINING AND TESTING EVENTS AND

FOR ALL OTHER EVENTS WITH MULTIPLE PLATFORMS OR SONAR WITH SOURCE LEVELS AT OR EXCEEDING 215 dB 

re 1 μPa @1 m 

Criteria group 

Moderate SL/ 

single platform 

cutoff distance 

(km) 

High SL/ 

multi-platform 

cutoff distance 

(km) 

Odontocetes ............................................................................................................................................................. 10 20 

Pinnipeds ................................................................................................................................................................. 5 10 

Mysticetes ................................................................................................................................................................ 10 20 

Beaked Whales ........................................................................................................................................................ 25 50 

Harbor Porpoise ....................................................................................................................................................... 20 40 

Notes: dB re 1 μPa @1 m: Decibels referenced to 1 micropascal at 1 meter; km: kilometer; SL: source level. 

There are no harbor porpoise in the HSTT Study Area, but are included in Table 16 for consistency with other Navy Proposed Rules. 

Tables 18–22 show the range to 

received sound levels in 6-dB steps from 

5 representative sonar bins and the 

percentage of animals that may be taken 

under each behavioral response 

function. Cells are shaded if the mean 

range value for the specified received 

level exceeds the distance cutoff range 

for a particular hearing group and 

therefore are not included in the 

estimated take. See Section 6.4.2.1.1 

(Methods for Analyzing Impacts from 

Sonars and Other Transducers) of the 

Navy’s application for further details on 

the derivation and use of the behavioral 

response functions, thresholds, and the 

cutoff distances, which were 

coordinated with NMFS. Table 18 

illustrates the potentially significant 

behavioral response for LFAS. 

BILLING CODE 3510–22–P 


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Table 18. Ranges to a Potentially Significant Behavioral Response for Sonar Bin LF5 over 

a Representative Range of Environments within the HSTT Study Area. 

178 

1 

(1-1) 97% 59% 92% 100% 

172 

2 

(1-2) 91% 30% 76% 99% 

166 3 

(1-5) 78% 20% 48% 97% 

160 

7 

(1-13) 58% 18% 27% 93% 

154 

16 

(1-30) 40% 17% 18% 83% 

148 35 

(1-85) 29% 16% 16% 66% 

142 81 

(1-230) 25% 13% 15% 45% 

136 

183 

(1-725) 23% 9% 15% 28% 

130 

404 

(1-1,525) 20% 5% 15% 18% 

124 886 

(1-3,025) 17% 2% 14% 14% 

118 1,973 12% 1% 13% 12% (725-5,775) 

112 4,472 6% 0% 9% 11% (900-18,275) 

106 8,936 

(900-54,525) 3% 0% 5% 11% 

100 27,580 

(900-88,775) 8% 

Note: Cells are shaded if the mean range value for the specified received level exceeds the distance cutoff range for a particular 

hearing group. Any impacts within the cutoff range for a criteria group are included in the estimated impacts. dB re lf!Pa2- s: 

decibels referenced to 1 micropascal squared second; m: meters 
29944 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

Tables 19 through Table 21 illustrates 

the potentially significant behavioral 

response for MFAS. 


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Table 19. Ranges to a Potentially Significant Behavioral Response for Sonar Bin MFl over 

a Representative Range of Environments within the HSTT Study Area. 

196 100% 100% 100% 100% 

190 239 

(190-250) 100% 98% 99% 100% 

184 

502 

(310-575) 99% 88% 98% 100% 

178 1,024 

(550-2,025) 97% 59% 92% 100% 

172 2,948 

(625-5,775) 91% 30% 76% 99% 

166 6,247 78% 20% 48% 97% (625-10,025) 

160 11,919 

(650-20,525) 

154 20,470 

( 650-62, 025) 

148 33,048 

(725-63,525) 

142 43,297 

(2,025-71,775) 

136 52,912 

(2,275-91,525) 

130 61,974 

(2,275-100,000*) 

124 66,546 

(2,275-100,000*) 

118 69,637 

(2,525-100,000*) 

112 73,010 

(2,525-100,000*) 

106 75,928 

(2,525-100,000*) 

100 78,899 

(2,525-100,000*) 

Note: Cells are shaded if the mean range value for the specified received level exceeds the distance cutoff range for a particular 

hearing group. Any impacts within the cutoff range for a criteria group are included in the estimated impacts. dB re 1f!Pa2- s: 

decibels referenced to 1 micropascal squared second; m: meters 

* Indicates maximum range to which acoustic model was run, a distance of approximately 100 kilometers from the sound 

source. 
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Table 20. Ranges to a Potentially Significant Behavioral Response for Sonar Bin MF4 over 

a Representative Range of Environments within the HSTT Study Area. 

196 100% 100% 100% 100% 

190 

17 

(1-17) 100% 98% 99% 100% 

184 34 

(1-35) 99% 88% 98% 100% 

178 

68 

(1-75) 97% 59% 92% 100% 

172 

145 

(130-300) 91% 30% 76% 99% 

166 388 

(270-875) 78% 20% 48% 97% 

160 841 

(470-1,775) 58% 18% 27% 93% 

154 1,748 40% 17% 18% 83% (700-6,025) 

148 3,163 

(1,025-13,775) 29% 16% 16% 66% 

142 5,564 

(1,275-27,025) 25% 13% 15% 45% 

136 8,043 23% 9% 15% 28% (1,525-54,275) 

130 17,486 18% (1,525--65,525) 

124 27,276 

(1,525-84,775) 14% 

118 33,138 

(2,775-85,275) 12% 

112 39,864 11% (3,775-100,000*) 

106 45,477 11% (5,275-100,000*) 

100 48,712 8% (5,275-100,000*) 

Note: Cells are shaded if the mean range value for the specified received level exceeds the distance cutoff range for a particular 

hearing group. Any impacts within the cutoff range for a criteria group are included in the estimated impacts. dB re 1f!Pa2- s: 

decibels referenced to 1 micropascal squared second; m: meters 

* Indicates maximum range to which acoustic model was run, a distance of approximately 100 kilometers from the sound 

source. 
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Table 21. Ranges to a Potentially Significant Behavioral Response for Sonar Bin MF5 over 

a Representative Range of Environments within the HSTT Study Area. 

196 100% 100% 100% 100% 

190 

2 

(1-3) 100% 98% 99% 100% 

184 4 

(1-7) 99% 88% 98% 100% 

178 

14 

(1-15) 97% 59% 92% 100% 

172 

29 

(1-30) 91% 30% 76% 99% 

166 59 

(1-70) 78% 20% 48% 97% 

160 133 

(1-340) 58% 18% 27% 93% 

154 

309 

(1-950) 40% 17% 18% 83% 

148 

688 

( 430-2,275) 29% 16% 16% 66% 

142 1,471 

(650-4,025) 25% 13% 15% 45% 

136 2,946 23% 9% 15% 28% (700-7 ,525) 

130 5,078 20% 5% 15% 18% (725-11,775) 

124 7,556 

(725-19 ,525) 17% 2% 14% 14% 

118 10,183 

(725-27,775) 12% 

112 13,053 11% (725--63,025) 

106 16,283 

(1,025-64,525) 11% 

100 20,174 

(1,025-70,525) 8% 

Note: Cells are shaded if the mean range value for the specified received level exceeds the distance cutoff range for a particular 

hearing group. Any impacts within the cutoff range for a criteria group are included in the estimated impacts. dB re 1 11Pa2 - s: 

decibels referenced to 1 micropascal squared second; m: meters 

* Indicates maximum range to which acoustic model was run, a distance of approximately 100 kilometers from the sound source. 
Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 29947 

Table 22 illustrates the potentially 

significant behavioral response for 

HFAS. 

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Table 22. Ranges to a Potentially Significant Behavioral Response for Sonar Bin HF4 over 

a Representative Range of Environments within the HSTT Study Area. 

196 100% 100% 100% 100% 

190 

8 

(1-16) 100% 98% 99% 100% 

184 17 

(1-35) 99% 88% 98% 100% 

178 

34 

(1-90) 97% 59% 92% 100% 

172 

68 

(1-180) 91% 30% 76% 99% 

166 133 

(12-430) 78% 20% 48% 97% 

160 255 

(30-750) 58% 18% 27% 93% 

154 

439 

(50-1,525) 40% 17% 18% 83% 

148 

694 

(85-2,275) 29% 16% 16% 66% 

142 989 

(110-3,525) 25% 13% 15% 45% 

136 1,378 23% 9% 15% 28% (170-4,775) 

130 1,792 20% 5% 15% 18% (270-6,025) 

124 2,259 

(320-7,525) 17% 2% 14% 14% 

118 2,832 

(320-8,525) 12% 1% 13% 12% 

112 3,365 6% 0% 9% 11% (320-10,525) 

106 3,935 

(320-12,275) 3% 0% 5% 11% 

100 4,546 

(320-16, 775) 1% 0% 2% 8% 

Note: Cells are shaded if the mean range value for the specified received level exceeds the distance cutoff range for a particular 

hearing group. Any impacts within the cutoff range for a criteria group are included in the estimated impacts. dB re 1 11Pa2- s: 

decibels referenced to 1 micropascal squared second; m: meters 

* Indicates maximum range to which acoustic model was run, a distance of approximately 100 kilometers from the sound 

source. 
29948 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

Explosives 

Phase III explosive criteria for 

behavioral thresholds for marine 

mammals is the hearing groups’ TTS 

threshold minus 5 dB (see Table 23 

below and Table 15 for the TTS 

thresholds for explosives) for events that 

contain multiple impulses from 

explosives underwater. This was the 

same approach as taken in Phase II for 

explosive analysis. See the Criteria and 

Thresholds for U.S. Navy Acoustic and 

Explosive Effects Analysis (Phase III) 

report (U.S. Department of the Navy, 

2017c) for detailed information on how 

the criteria and thresholds were derived. 

TABLE 23—PHASE III BEHAVIORAL

THRESHOLDS FOR EXPLOSIVES FOR

MARINE MAMMALS

Medium 

Functional 

hearing 

group 

SEL 

(weighted) 

Underwater ....... LF 163 

Underwater ....... MF 165 

Underwater ....... HF 135 

Underwater ....... PW 165 

Underwater ....... OW 183 

Note: Weighted SEL thresholds in dB re 1 

μPa2s underwater. 

Navy’s Acoustic Effects Model 

Sonar and Other Transducers and 

Explosives 

The Navy’s Acoustic Effects Model 

calculates sound energy propagation 

from sonar and other transducers and 

explosives during naval activities and 

the sound received by animat 

dosimeters. Animat dosimeters are 

virtual representations of marine 

mammals distributed in the area around 

the modeled naval activity that each 

records its individual sound ‘‘dose.’’ 

The model bases the distribution of 

animats over the HSTT Study Area on 

the density values in the Navy Marine 

Species Density Database and 

distributes animats in the water column 

proportional to the known time that 

species spend at varying depths. 

The model accounts for 

environmental variability of sound 

propagation in both distance and depth 

when computing the received sound 

level received by the animats. The 

model conducts a statistical analysis 

based on multiple model runs to 

compute the estimated effects on 

animals. The number of animats that 

exceed the thresholds for effects is 

tallied to provide an estimate of the 

number of marine mammals that could 

be affected. 

Assumptions in the Navy model 

intentionally err on the side of 

overestimation when there are 

unknowns. Naval activities are modeled 

as though they would occur regardless 

of proximity to marine mammals 

meaning that no mitigation is 

considered (i.e., no power down or shut 

down modeled) and without any 

avoidance of the activity by the animal. 

The final step of the quantitative 

analysis of acoustic effects is to consider 

the implementation of mitigation and 

the possibility that marine mammals 

would avoid continued or repeated 

sound exposures. For more information 

on this process, see the discussion in 

the ‘‘Take Requests’’ subsection below. 

Many explosions from ordnance such as 

bombs and missiles actually occur upon 

impact with above-water targets. 

However, for this analysis, sources such 

as these were modeled as exploding 

underwater. This overestimates the 

amount of explosive and acoustic 

energy entering the water. 

The model estimates the impacts 

caused by individual training and 

testing exercises. During any individual 

modeled event, impacts to individual 

animats are considered over 24-hour 

periods. The animats do not represent 

actual animals, but rather they represent 

a distribution of animals based on 

density and abundance data, which 

allows for a statistical analysis of the 

number of instances that marine 

mammals may be exposed to sound 

levels resulting in an effect. Therefore, 

the model estimates the number of 

instances in which an effect threshold 

was exceeded over the course of a year, 

but does not estimate the number of 

individual marine mammals that may be 

impacted over a year (i.e., some marine 

mammals could be impacted several 

times, while others would not 

experience any impact). A detailed 

explanation of the Navy’s Acoustic 

Effects Model is provided in the 

technical report Quantifying Acoustic 

Impacts on Marine Mammals and Sea 

Turtles: Methods and Analytical 

Approach for Phase III Training and 

Testing report (U.S. Department of the 

Navy, 2017b). 

Air Guns and Pile Driving 

The Navy’s quantitative analysis 

estimates the sound and energy received 

by marine mammals distributed in the 

area around planned Navy activities 

involving air guns. The analysis for air 

guns was similar to explosives as an 

impulsive source, except explosive 

impulsive sources were placed into bins 

based on net explosive weights, while 

each non-explosive impulsive source 

(air guns) was assigned its own unique 

bin. The impulsive model used in the 

Navy’s analysis used metrics to describe 

the sound received by the animats and 

the SPLrms criteria was only applied to 

air guns. See the technical report titled 

Quantifying Acoustic Impacts on 

Marine Mammals and Sea Turtles: 

Methods and Analytical Approach for 

Phase III Training and Testing report 

(U.S. Department of the Navy, 2017b) 

for additional details. 

Underwater noise effects from pile 

driving and vibratory pile extraction 

were modeled using actual measures of 

impact pile driving and vibratory 

removal during construction of an 

Elevated Causeway System (Illingworth 

and Rodkin, 2015, 2016). A conservative 

estimate of spreading loss of sound in 

shallow coastal waters (i.e., 

transmission loss = 16.5 * Log10 

(radius)) was applied based on 

spreading loss observed in actual 

measurements. Inputs used in the model 

are provided in Section 1.4.1.3 (Pile 

Driving) of the Navy’s rulemaking/LOA 

application, including source levels; the 

number of strikes required to drive a 

pile and the duration of vibratory 

removal per pile; the number of piles 

driven or removed per day; and the 

number of days of pile driving and 

removal. 

Range to Effects 

The following section provides range 

to effects for sonar and other active 

acoustic sources as well as explosives to 

specific acoustic thresholds determined 

using the Navy Acoustic Effects Model. 

Marine mammals exposed within these 

ranges for the shown duration are 

predicted to experience the associated 

effect. Range to effects is important 

information not only for predicting 

acoustic impacts, but also in verifying 

the accuracy of model results against 

real-world situations and determining 

adequate mitigation ranges to avoid 

higher level effects, especially 

physiological effects to marine 

mammals. 

Sonar 

The range to received sound levels in 

6-dB steps from 5 representative sonar 

bins and the percentage of the total 

number of animals that may exhibit a 

significant behavioral response (and 

therefore Level B harassment) under 

each behavioral response function are 

shown in Table 18 through Table 22 

above, respectively. See Section 

6.4.2.1.1 (Impact Ranges for Sonar and 

Other Transducers) of the Navy’s 

rulemaking/LOA application for 

additional details on the derivation and 

use of the behavioral response 

functions, thresholds, and the cutoff 

distances. 

The ranges to the PTS for five 

representative sonar systems for an 


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exposure of 30 seconds is shown in 

Table 24 relative to the marine 

mammal’s functional hearing group. 

This period (30 seconds) was chosen 

based on examining the maximum 

amount of time a marine mammal 

would realistically be exposed to levels 

that could cause the onset of PTS based 

on platform (e.g., ship) speed and a 

nominal animal swim speed of 

approximately 1.5 m per second. The 

ranges provided in the table include the 

average range to PTS, as well as the 

range from the minimum to the 

maximum distance at which PTS is 

possible for each hearing group. 

TABLE 24—RANGE TO PERMANENT THRESHOLD SHIFT (METERS) FOR FIVE REPRESENTATIVE SONAR SYSTEMS

Functional hearing group 

Approximate range in meters for PTS from 30 seconds exposure 

Sonar bin LF Sonar bin MF1 Sonar bin MF4 Sonar bin MF5 Sonar bin HF4 

Low-frequency Cetacean ..................................................... 0 (0–0) 65 (65–65) 14 (0–15) 0 (0–0) 0 (0–0) 

Mid-frequency Cetacean ...................................................... 0 (0–0) 16 (16–16) 3 (3–3) 0 (0–0) 1 (0–2) 

High-frequency Cetacean .................................................... 0 (0–0) 181 (180–190) 30 (30–30) 9 (8–10) 30 (8–80) 

Otariidae ............................................................................... 0 (0–0) 6 (6–6) 0 (0–0) 0 (0–0) 0 (0–0)

Phocinae .............................................................................. 0 (0–0) 45 (45–45) 11 (11–11) 0 (0–0) 0 (0–0) 

1PTS ranges extend from the sonar or other active acoustic sound source to the indicated distance. The average range to PTS is provided as 

well as the range from the estimated minimum to the maximum range to PTS in parenthesis. 

The tables below illustrate the range 

to TTS for 1, 30, 60, and 120 seconds 

from 5 representative sonar systems (see 

Table 25 through Table 29). 

TABLE 25—RANGES TO TEMPORARY THRESHOLD SHIFT FOR SONAR BIN LF5 OVER A REPRESENTATIVE RANGE OF

ENVIRONMENTS WITHIN THE HSTT STUDY AREA

Hearing group 

Approximate TTS ranges 

(meters) 1

Sonar bin LF5M 

(low frequency sources <180 dB source level) 

1 second 30 seconds 60 seconds 120 seconds 

Low-frequency Cetacean ................................................................................. 3 (0–4) 3 (0–4) 3 (0–4) 3 (0–4) 

Mid-frequency Cetacean .................................................................................. 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 

High-frequency Cetacean ................................................................................ 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 

Otariidae .......................................................................................................... 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 

Phocinae .......................................................................................................... 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 

1 Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. 

TABLE 26—RANGES TO TEMPORARY THRESHOLD SHIFT FOR SONAR BIN MF1 OVER A REPRESENTATIVE RANGE OF

ENVIRONMENTS WITHIN THE HSTT STUDY AREA

Hearing group 

Approximate TTS ranges 

(meters) 1

Sonar bin MF1 

(e.g., SQS–53 ASW hull-mounted sonar) 

1 second 30 seconds 60 seconds 120 seconds 

Low-frequency Cetacean ......................................... 903 (850–1,025) 903 (850–1,025) 1,264 (1,025–2,275) 1,839 (1,275–3,025) 

Mid-frequency Cetacean .......................................... 210 (210–210) 210 (210–210) 302 (300–310) 379 (370–390) 

High-frequency Cetacean ........................................ 3,043 (1,525–4,775) 3,043 (1,525–4,775) 4,739 (2,025–6,275) 5,614 (2,025–7,525) 

Otariidae .................................................................. 65 (65–65) 65 (65–65) 106 (100–110) 137 (130–140) 

Phocinae .................................................................. 669 (650–725) 669 (650–725) 970 (900–1,025) 1,075 (1,025–1,525) 

1 Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. 


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29950 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

TABLE 27—RANGES TO TEMPORARY THRESHOLD SHIFT (METERS) FOR SONAR BIN MF4 OVER A REPRESENTATIVE RANGE

OF ENVIRONMENTS WITHIN THE HSTT STUDY AREA

Hearing group 

Approximate TTS ranges 

(meters) 1

Sonar bin MF4 

(e.g., AQS–22 ASW dipping sonar) 

1 second 30 seconds 60 seconds 120 seconds 

Low-frequency Cetacean ......................................... 77 (0–85) 162 (150–180) 235 (220–290) 370 (310–600) 

Mid-frequency Cetacean .......................................... 22 (22–22) 35 (35–35) 49 (45–50) 70 (70–70) 

High-frequency Cetacean ........................................ 240 (220–300) 492 (440–775) 668 (550–1,025) 983 (825–2,025) 

Otariidae .................................................................. 8 (8–8) 15 (15–15) 19 (19–19) 25 (25–25) 

Phocinae .................................................................. 65 (65–65) 110 (110–110) 156 (150–170) 269 (240–460) 

1 Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. 

TABLE 28—RANGES TO TEMPORARY THRESHOLD SHIFT (METERS) FOR SONAR BIN MF5 OVER A REPRESENTATIVE RANGE

OF ENVIRONMENTS WITHIN THE HSTT STUDY AREA

Hearing group 

Approximate TTS ranges 

(meters) 1

Sonar bin MF5 

(e.g., SSQ–62 ASW sonobuoy) 

1 second 30 seconds 60 seconds 120 seconds 

Low-frequency Cetacean ......................................... 10 (0–12) 10 (0–12) 14 (0–18) 21 (0–25) 

Mid-frequency Cetacean .......................................... 6 (0–9) 6 (0–9) 12 (0–13) 17 (0–21) 

High-frequency Cetacean ........................................ 118 (100–170) 118 (100–170) 179 (150–480) 273 (210–700) 

Otariidae .................................................................. 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 

Phocinae .................................................................. 9 (8–10) 9 (8–10) 14 (14–16) 21 (21–25) 

1 Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. 

TABLE 29—RANGES TO TEMPORARY THRESHOLD SHIFT (METERS) FOR SONAR BIN HF4 OVER A REPRESENTATIVE RANGE

OF ENVIRONMENTS WITHIN THE HSTT STUDY AREA

Hearing group 

Approximate TTS ranges 

(meters) 1

Sonar bin HF4 

(e.g., SQS–20 mine hunting sonar) 

1 second 30 seconds 60 seconds 120 seconds 

Low-frequency Cetacean ......................................... 1 (0–3) 2 (0–5) 4 (0–7) 6 (0–11) 

Mid-frequency Cetacean .......................................... 10 (4–17) 17 (6–35) 24 (7–60) 34 (9–90) 

High-frequency Cetacean ........................................ 168 (25–550) 280 (55–775) 371 (80–1,275) 470 (100–1,525) 

Otariidae .................................................................. 0 (0–0) 0 (0–0) 0 (0–0) 1 (0–1) 

Phocinae .................................................................. 2 (0–5) 5 (2–8) 8 (3–13) 11 (4–22) 

1 Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. 

Explosives 

The following section provides the 

range (distance) over which specific 

physiological or behavioral effects are 

expected to occur based on the 

explosive criteria (see Chapter 6.5.2.1.1 

of the Navy’s rulemaking/LOA 

application and the Criteria and 

Thresholds for U.S. Navy Acoustic and 

Explosive Effects Analysis (Phase III) 

report (U.S. Department of the Navy, 

2017c) and the explosive propagation 

calculations from the Navy Acoustic 

Effects Model (see Chapter 6.5.2.1.3, 

Navy Acoustic Effects Model of the 

Navy’s rulemaking/LOA application). 

The range to effects are shown for a 

range of explosive bins, from E1 (up to 

0.25 lb net explosive weight) to E12 (up 

to 1,000 lb net explosive weight) (Tables 

30 through 35). Ranges are determined 

by modeling the distance that noise 

from an explosion will need to 

propagate to reach exposure level 

thresholds specific to a hearing group 

that will cause behavioral response (to 

the degree of a take), TTS, PTS, and 

non-auditory injury. Ranges are 

provided for a representative source 

depth and cluster size for each bin. For 

events with multiple explosions, sound 

from successive explosions can be 

expected to accumulate and increase the 

range to the onset of an impact based on 

SEL thresholds. Range to effects is 

important information in not only 


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predicting impacts from explosives, but 

also in verifying the accuracy of model 

results against real-world situations and 

determining adequate mitigation ranges 

to avoid higher level effects, especially 

physiological effects to marine 

mammals. For additional information 

on how ranges to impacts from 

explosions were estimated, see the 

technical report Quantifying Acoustic 

Impacts on Marine Mammals and Sea 

Turtles: Methods and Analytical 

Approach for Phase III Training and 

Testing (U.S. Navy, 2017b). 

Table 30 shows the minimum, 

average, and maximum ranges to onset 

of auditory and behavioral effects for 

high-frequency cetaceans based on the 

developed thresholds. 

TABLE 30—SEL-BASED RANGES (METERS) TO ONSET PTS, ONSET TTS, AND BEHAVIORAL REACTION FOR HIGHFREQUENCY CETACEANS

Range to effects for explosives: high frequency cetacean 1

Bin Source depth 

(m) Cluster size PTS TTS Behavioral 

E1 ................................... 0.1 1 353 (130–825) 1,234 (290–3,025) 2,141 (340–4,775) 

25 1,188 (280–3,025) 3,752 (490–8,525) 5,196 (675–12,275) 

E2 ................................... 0.1 1 425 (140–1,275) 1,456 (300–3,525) 2,563 (390–5,275) 

10 988 (280–2,275) 3,335 (480–7,025) 4,693 (650–10,275) 

E3 ................................... 0.1 1 654 (220–1,525) 2,294 (350–4,775) 3,483 (490–7,775) 

12 1,581 (300–3,525) 4,573 (650–10,275) 6,188 (725–14,775) 

18.25 1 747 (550–1,525) 3,103 (950–6,025) 5,641 (1,000–9,275) 

12 1,809 (875–4,025) 7,807 (1,025–12,775) 10,798 (1,025–17,775) 

E4 ................................... 3 2 2,020 (1,025–3,275) 3,075 (1,025–6,775) 3,339 (1,025–9,775) 

15.25 2 970 (600–1,525) 4,457 (1,025–8,525) 6,087 (1,275–12,025) 

19.8 2 1,023 (1,000–1,025) 4,649 (2,275–8,525) 6,546 (3,025–11,025) 

198 2 959 (875–1,525) 4,386 (3,025–7,525) 5,522 (3,025–9,275) 

E5 ................................... 0.1 25 2,892 (440–6,275) 6,633 (725–16,025) 8,925 (800–22,775) 

15.25 25 4,448 (1,025–7,775) 10,504 (1,525–18,275) 13,605 (1,775–24,775) 

E6 ................................... 0.1 1 1,017 (280–2,525) 3,550 (490–7,775) 4,908 (675–12,275) 

3 1 2,275 (2,025–2,525) 6,025 (4,525–7,275) 7,838 (6,275–9,775) 

15.25 1 1,238 (625–2,775) 5,613 (1,025–10,525) 7,954 (1,275–14,275) 

E7 ................................... 3 1 3,150 (2,525–3,525) 7,171 (5,525–8,775) 8,734 (7,275–10,525) 

18.25 1 2,082 (925–3,525) 6,170 (1,275–10,525) 8,464 (1,525–16,525) 

E8 ................................... 0.1 1 1,646 (775–2,525) 4,322 (1,525–9,775) 5,710 (1,525–14,275) 

45.75 1 1,908 (1,025–4,775) 5,564 (1,525–12,525) 7,197 (1,525–18,775) 

E9 ................................... 0.1 1 2,105 (850–4,025) 4,901 (1,525–12,525) 6,700 (1,525–16,775) 

E10 ................................. 0.1 1 2,629 (875–5,275) 5,905 (1,525–13,775) 7,996 (1,525–20,025) 

E11 ................................. 18.5 1 3,034 (1,025–6,025) 7,636 (1,525–16,525) 9,772 (1,775–21,525) 

45.75 1 2,925 (1,525–6,025) 7,152 (2,275–18,525) 9,011 (2,525–24,525) 

E12 ................................. 0.1 1 2,868 (975–5,525) 6,097 (2,275–14,775) 8,355 (4,275–21,275) 

3 3,762 (1,525–8,275) 7,873 (3,775–20,525) 10,838 (4,275–26,525) 

1Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. 

E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. 

Table 31 shows the minimum, 

average, and maximum ranges to onset 

of auditory and behavioral effects for 

mid-frequency cetaceans based on the 

developed thresholds. 

TABLE 31—SEL-BASED RANGES (METERS) TO ONSET PTS, ONSET TTS, AND BEHAVIORAL REACTION FOR MIDFREQUENCY CETACEANS

Range to effects for explosives: mid-frequency cetacean 1

Bin Source depth 

(m) Cluster size PTS TTS Behavioral 

E1 ............................................... 0.1 1 25 (25–25) 118 (80–210) 178 (100–320) 

25 107 (75–170) 476 (150–1,275) 676 (240–1,525) 

E2 ............................................... 0.1 1 30 (30–35) 145 (95–240) 218 (110–400) 

10 88 (65–130) 392 (140–825) 567 (190–1,275) 

E3 ............................................... 0.1 1 50 (45–65) 233 (110–430) 345 (130–600) 

12 153 (90–250) 642 (220–1,525) 897 (270–2,025) 

18.25 1 38 (35–40) 217 (190–900) 331 (290–850) 

12 131 (120–250) 754 (550–1,525) 1,055 (600–2,525) 

E4 ............................................... 3 2 139 (110–160) 1,069 (525–1,525) 1,450 (875–1,775) 

15.25 2 71 (70–75) 461 (400–725) 613 (470–750) 

19.8 2 69 (65–70) 353 (350–360) 621 (600–650) 

198 2 49 (0–55) 275 (270–280) 434 (430–440) 

E5 ............................................... 0.1 25 318 (130–625) 1,138 (280–3,025) 1,556 (310–3,775) 

15.25 25 312 (290–725) 1,321 (675–2,525) 1,980 (850–4,275) 


sradovich on DSK3GMQ082PROD with PROPOSALS2
29952 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

TABLE 31—SEL-BASED RANGES (METERS) TO ONSET PTS, ONSET TTS, AND BEHAVIORAL REACTION FOR MIDFREQUENCY CETACEANS—Continued 

Range to effects for explosives: mid-frequency cetacean 1

Bin Source depth 

(m) Cluster size PTS TTS Behavioral 

E6 ............................................... 0.1 1 98 (70–170) 428 (150–800) 615 (210–1,525) 

3 1 159 (150–160) 754 (650–850) 1,025 (1,025–1,025) 

15.25 1 88 (75–180) 526 (450–875) 719 (500–1,025) 

E7 ............................................... 3 1 240 (230–260) 1,025 (1,025–1,025) 1,900 (1,775–2,275) 

18.25 1 166 (120–310) 853 (500–1,525) 1,154 (550–1,775) 

E8 ............................................... 0.1 1 160 (150–170) 676 (500–725) 942 (600–1,025) 

45.75 1 128 (120–170) 704 (575–2,025) 1,040 (750–2,525) 

E9 ............................................... 0.1 1 215 (200–220) 861 (575–950) 1,147 (650–1,525) 

E10 ............................................. 0.1 1 275 (250–480) 1,015 (525–2,275) 1,424 (675–3,275) 

E11 ............................................. 18.5 1 335 (260–500) 1,153 (650–1,775) 1,692 (775–3,275) 

45.75 1 272 (230–825) 1,179 (825–3,025) 1,784 (1,000–4,275) 

E12 ............................................. 0.1 1 334 (310–350) 1,151 (700–1,275) 1,541 (800–3,525) 

0.1 3 520 (450–550) 1,664 (800–3,525) 2,195 (925–4,775) 

1Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. 

E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. 

Table 32 shows the minimum, 

average, and maximum ranges to onset 

of auditory and behavioral effects for 

low-frequency cetaceans based on the 

developed thresholds. 

TABLE 32—SEL-BASED RANGES (METERS) TO ONSET PTS, ONSET TTS, AND BEHAVIORAL REACTION FOR LOWFREQUENCY CETACEANS

Range to effects for explosives: low frequency cetacean 1

Bin Source depth 

(m) Cluster size PTS TTS Behavioral 

E1 ............................................... 0.1 1 51 (40–70) 227 (100–320) 124 (70–160) 

25 205 (95–270) 772 (270–1,275) 476 (190–725) 

E2 ............................................... 0.1 1 65 (45–95) 287 (120–400) 159 (80–210) 

10 176 (85–240) 696 (240–1,275) 419 (160–625) 

E3 ............................................... 0.1 1 109 (65–150) 503 (190–1,000) 284 (120–430) 

12 338 (130–525) 1,122 (320–7,775) 761 (240–6,025) 

18.25 1 205 (170–340) 996 (410–2,275) 539 (330–1,275) 

12 651 (340–1,275) 3,503 (600–8,275) 1,529 (470–3,275) 

E4 ............................................... 3 2 493 (440–1,000) 2,611 (1,025–4,025) 1,865 (950–2,775) 

15.25 2 583 (350–850) 3,115 (1,275–5,775) 1,554 (1,000–2,775) 

19.8 2 378 (370–380) 1,568 (1,275–1,775) 926 (825–950) 

198 2 299 (290–300) 2,661 (1,275–3,775) 934 (900–950) 

E5 ............................................... 0.1 25 740 (220–6,025) 2,731 (460–22,275) 1,414 (350–14,275) 

15.25 25 1,978 (1,025–5,275) 8,188 (3,025–19,775) 4,727 (1,775–11,525) 

E6 ............................................... 0.1 1 250 (100–420) 963 (260–7,275) 617 (200–1,275) 

3 1 711 (525–825) 3,698 (1,525–4,275) 2,049 (1,025–2,525) 

15.25 1 718 (390–2,025) 3,248 (1,275–8,525) 1,806 (950–4,525) 

E7 ............................................... 3 1 1,121 (850–1,275) 5,293 (2,025–6,025) 3,305 (1,275–4,025) 

18.25 1 1,889 (1,025–2,775) 6,157 (2,775–11,275) 4,103 (2,275–7,275) 

E8 ............................................... 0.1 1 460 (170–950) 1,146 (380–7,025) 873 (280–3,025) 

45.75 1 1,049 (550–2,775) 4,100 (1,025–14,275) 2,333 (800–7,025) 

E9 ............................................... 0.1 1 616 (200–1,275) 1,560 (450–12,025) 1,014 (330–5,025) 

E10 ............................................. 0.1 1 787 (210–2,525) 2,608 (440–18,275) 1,330 (330–9,025) 

E11 ............................................. 18.5 1 4,315 (2,025–8,025) 10,667 (4,775–26,775) 7,926 (3,275–21,025) 

45.75 1 1,969 (775–5,025) 9,221 (2,525–29,025) 4,594 (1,275–16,025) 

E12 ............................................. 0.1 1 815 (250–3,025) 2,676 (775–18,025) 1,383 (410–8,525) 

0.1 3 1,040 (330–6,025) 4,657 (1,275–31,275) 2,377 (700–16,275) 

1Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. 

E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. 

Table 33 shows the minimum, 

average, and maximum ranges to onset 

of auditory and behavioral effects for 

phocids based on the developed 

thresholds. 


sradovich on DSK3GMQ082PROD with PROPOSALS2
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TABLE 33—SEL-BASED RANGES (METERS) TO ONSET PTS, ONSET TTS, AND BEHAVIORAL REACTION FOR PHOCIDS

Range to effects for explosives: phocids 1

Bin Source depth 

(m) Cluster size PTS TTS Behavioral 

E1 ............................................... 0.1 1 45 (40–65) 210 (100–290) 312 (130–430) 

25 190 (95–260) 798 (280–1,275) 1,050 (360–2,275) 

E2 ............................................... 0.1 1 58 (45–75) 258 (110–360) 383 (150–550) 

10 157 (85–240) 672 (240–1,275) 934 (310–1,525) 

E3 ............................................... 0.1 1 96 (60–120) 419 (160–625) 607 (220–900) 

12 277 (120–390) 1,040 (370–2,025) 1,509 (525–6,275) 

18.25 1 118 (110–130) 621 (500–1,275) 948 (700–2,025) 

12 406 (330–875) 1,756 (1,025–4,775) 3,302 (1,025–6,275) 

E4 ............................................... 3 2 405 (300–430) 1,761 (1,025–2,775) 2,179 (1,025–3,275) 

15.25 2 265 (220–430) 1,225 (975–1,775) 1,870 (1,025–3,275) 

19.8 2 220 (220–220) 991 (950–1,025) 1,417 (1,275–1,525) 

198 2 150 (150–150) 973 (925–1,025) 2,636 (2,025–3,525) 

E5 ............................................... 0.1 25 569 (200–850) 2,104 (725–9,275) 2,895 (825–11,025) 

15.25 25 920 (825–1,525) 5,250 (2,025–10,275) 7,336 (2,275–16,025) 

E6 ............................................... 0.1 1 182 (90–250) 767 (270–1,275) 1,011 (370–1,775) 

3 1 392 (340–440) 1,567 (1,275–1,775) 2,192 (2,025–2,275) 

15.25 1 288 (250–600) 1,302 (1,025–3,275) 2,169 (1,275–5,775) 

E7 ............................................... 3 1 538 (450–625) 2,109 (1,775–2,275) 2,859 (2,775–3,275) 

18.25 1 530 (460–750) 2,617 (1,025–4,525) 3,692 (1,525–5,275) 

E8 ............................................... 0.1 1 311 (290–330) 1,154 (625–1,275) 1,548 (725–2,275) 

45.75 1 488 (380–975) 2,273 (1,275–5,275) 3,181 (1,525–8,025) 

E9 ............................................... 0.1 1 416 (350–470) 1,443 (675–2,025) 1,911 (800–3,525) 

E10 ............................................. 0.1 1 507 (340–675) 1,734 (725–3,525) 2,412 (800–5,025) 

E11 ............................................. 18.5 1 1,029 (775–1,275) 5,044 (2,025–8,775) 6,603 (2,525–14,525) 

45.75 1 881 (700–2,275) 3,726 (2,025–8,775) 5,082 (2,025–13,775) 

E12 ............................................. 0.1 1 631 (450–750) 1,927 (800–4,025) 2,514 (925–5,525) 

0.1 3 971 (550–1,025) 2,668 (1,025–6,275) 3,541 (1,775–9,775) 

1Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. 

E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. 

Table 34 shows the minimum, 

average, and maximum ranges to onset 

of auditory and behavioral effects for 

ottariids based on the developed 

thresholds. 

TABLE 34—SEL-BASED RANGES (METERS) TO ONSET PTS, ONSET TTS, AND BEHAVIORAL REACTION FOR OTARIIDS

Range to effects for explosives: otariids 1range to effects for explosives: mid-frequency cetacean 

Bin Source depth 

(m) Cluster size PTS TTS Behavioral 

E1 ............................................... 0.1 1 7 (7–7) 34 (30–40) 56 (45–70) 

25 30 (25–35) 136 (80–180) 225 (100–320) 

E2 ............................................... 0.1 1 9 (9–9) 41 (35–55) 70 (50–95) 

10 25 (25–30) 115 (70–150) 189 (95–250) 

E3 ............................................... 0.1 1 16 (15–19) 70 (50–95) 115 (70–150) 

12 45 (35–65) 206 (100–290) 333 (130–450) 

18.25 1 15 (15–15) 95 (90–100) 168 (150–310) 

12 55 (50–60) 333 (280–750) 544 (440–1,025) 

E4 ............................................... 3 2 64 (40–85) 325 (240–340) 466 (370–490) 

15.25 2 30 (30–35) 205 (170–300) 376 (310–575) 

19.8 2 25 (25–25) 170 (170–170) 290 (290–290) 

198 2 17 (0–25) 117 (110–120) 210 (210–210) 

E5 ............................................... 0.1 25 98 (60–120) 418 (160–575) 626 (240–1,000) 

15.25 25 151 (140–260) 750 (650–1,025) 1,156 (975–2,025) 

E6 ............................................... 0.1 1 30 (25–35) 134 (75–180) 220 (100–320) 

3 1 53 (50–55) 314 (280–390) 459 (420–525) 

15.25 1 36 (35–40) 219 (200–380) 387 (340–625) 

E7 ............................................... 3 1 93 (90–100) 433 (380–500) 642 (550–800) 

18.25 1 73 (70–75) 437 (360–525) 697 (600–850) 

E8 ............................................... 0.1 1 50 (50–50) 235 (220–250) 385 (330–450) 

45.75 1 55 (55–60) 412 (310–775) 701 (500–1,525) 

E9 ............................................... 0.1 1 68 (65–70) 316 (280–360) 494 (390–625) 

E10 ............................................. 0.1 1 86 (80–95) 385 (240–460) 582 (390–800) 

E11 ............................................. 18.5 1 158 (150–200) 862 (750–975) 1,431 (1,025–2,025) 

45.75 1 117 (110–130) 756 (575–1,525) 1,287 (950–2,775) 

E12 ............................................. 0.1 1 104 (100–110) 473 (370–575) 709 (480–1,025) 


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29954 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

TABLE 34—SEL-BASED RANGES (METERS) TO ONSET PTS, ONSET TTS, AND BEHAVIORAL REACTION FOR OTARIIDS— 

Continued 

Range to effects for explosives: otariids 1range to effects for explosives: mid-frequency cetacean 

Bin Source depth 

(m) Cluster size PTS TTS Behavioral 

0.1 3 172 (170–180) 694 (480–1,025) 924 (575–1,275) 

1Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. 

E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. 

Table 35 which show the minimum, 

average, and maximum ranges due to 

varying propagation conditions to nonauditory injury as a function of animal 

mass and explosive bin (i.e., net 

explosive weight). These ranges 

represent the larger of the range to slight 

lung injury or gastrointestinal tract 

injury for representative animal masses 

ranging from 10 to 72,000 kg and 

different explosive bins ranging from 

0.25 to 1,000 lb net explosive weight. 

Animals within these water volumes 

would be expected to receive minor 

injuries at the outer ranges, increasing to 

more substantial injuries, and finally 

mortality as an animal approaches the 

detonation point. 

TABLE 35—RANGES 1 TO 50 PERCENT

NON-AUDITORY INJURY RISK FOR

ALL MARINE MAMMAL HEARING

GROUPS AS A FUNCTION OF ANIMAL

MASS

[10–72,000 kg] 

Bin Range (m) 

(min-max) 

E1 ..................................... 12 (11–13) 

E2 ..................................... 15 (15–20) 

E3 ..................................... 25 (25–30) 

E4 ..................................... 32 (0–75) 

E5 ..................................... 40 (35–140) 

E6 ..................................... 52 (40–120) 

E7 ..................................... 145 (100–500) 

E8 ..................................... 117 (75–400) 

E9 ..................................... 120 (90–290) 

E10 ................................... 174 (100–480) 

E11 ................................... 443 (350–1,775) 

TABLE 35—RANGES 1 TO 50 PERCENT

NON-AUDITORY INJURY RISK FOR

ALL MARINE MAMMAL HEARING

GROUPS AS A FUNCTION OF ANIMAL

MASS—Continued 

[10–72,000 kg] 

Bin Range (m) 

(min-max) 

E12 ................................... 232 (110–775) 

Note: 

1Average distance (m) to mortality is depicted above the minimum and maximum distances which are in parentheses. 

E13 not modeled due to surf zone use and 

lack of marine mammal receptors at sitespecific location. Differences between bins 

E11 and E12 due to different ordnance types 

and differences in model parameters. 

Ranges to mortality, based on animal 

mass, are show in Table 36 below. 

TABLE 36—RANGES 1 TO 50 PERCENT MORTALITY RISK FOR ALL MARINE MAMMAL HEARING GROUPS AS A FUNCTION OF

ANIMAL MASS

Bin 

Animal mass intervals (kg) 1

10 250 1,000 5,000 25,000 72,000 

E1 ............................................................. 3 (2–3) 0 (0–3) 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 

E2 ............................................................. 4 (3–5) 1 (0–4) 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 

E3 ............................................................. 8 (6–10) 4 (2–8) 1 (0–2) 0 (0–0) 0 (0–0) 0 (0–0) 

E4 ............................................................. 15 (0–35) 9 (0–30) 4 (0–8) 2 (0–6) 0 (0–3) 0 (0–2) 

E5 ............................................................. 13 (11–45) 7 (4–35) 3 (3–12) 2 (0–8) 0 (0–2) 0 (0–2) 

E6 ............................................................. 18 (14–55) 10 (5–45) 5 (3–15) 3 (2–10) 0 (0–3) 0 (0–2) 

E7 ............................................................. 67 (55–180) 35 (18–140) 16 (12–30) 10 (8–20) 5 (4–9) 4 (3–7) 

E8 ............................................................. 50 (24–110) 27 (9–55) 13 (0–20) 9 (4–13) 4 (0–6) 3 (0–5) 

E9 ............................................................. 32 (30–35) 20 (13–30) 10 (8–12) 7 (6–9) 4 (3–4) 3 (2–3) 

E10 ........................................................... 56 (40–190) 25 (16–130) 13 (11–16) 9 (7–11) 5 (4–5) 4 (3–4) 

E11 ........................................................... 211 (180–500) 109 (60–330) 47 (40–100) 30 (25–65) 15 (0–25) 13 (11–22) 

E12 ........................................................... 94 (50–300) 35 (20–230) 16 (13–19) 11 (9–13) 6 (5–8) 5 (4–8) 

Note: 

1Average distance (m) to mortality is depicted above the minimum and maximum distances which are in parentheses. 

E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. 

Differences between bins E11 and E12 due to different ordnance types and differences in model parameters (see Table 6–42 for details). 

Air Guns 

Table 37 and Table 38 present the 

approximate ranges in meters to PTS, 

TTS, and potential behavioral reactions 

for air guns for 1 and 10 pulses, 

respectively. Ranges are specific to the 

HSTT Study Area and also to each 

marine mammal hearing group, 

dependent upon their criteria and the 

specific locations where animals from 

the hearing groups and the air gun 

activities could overlap. Small air guns 

(12–60 in3) would be used during 

testing activities in the offshore areas of 

the Southern California Range Complex 

and in the Hawaii Range Complex. 

Generated impulses would have short 

durations, typically a few hundred 

milliseconds, with dominant 

frequencies below 1 kHz. The SPL and 

SPL peak (at a distance 1 m from the air 

gun) would be approximately 215 dB re 

1 mPa and 227 dB re 1 mPa, respectively, 

if operated at the full capacity of 60 in3. 

The size of the air gun chamber can be 

adjusted, which would result in lower 

SPLs and SEL per shot. Single, small air 

guns lack the peak pressures that could 

cause non-auditory injury (see Finneran 


sradovich on DSK3GMQ082PROD with PROPOSALS2
Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 29955 

et al., (2015)); therefore, potential impacts could include PTS, TTS, and 

behavioral reactions. 

TABLE 37—RANGE TO EFFECTS (METERS) FROM AIR GUNS FOR 1 PULSE

Range to effects for air guns 1 for 1 pulse (m) 

Hearing group PTS 

(SEL) 

PTS 

(peak SPL) 

TTS 

(SEL) 

TTS 

(peak SPL) Behavioral 2

High-Frequency Cetacean ............................................... 0 (0–0) 18 (15–25) 1 (0–2) 33 (25–80) 702 (290–1,525) 

Low-Frequency Cetacean ................................................ 3 (3–4) 2 (2–3) 27 (23–35) 5 (4–7) 651 (200–1,525) 

Mid-Frequency Cetacean ................................................. 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 689 (290–1,525) 

Otariidae ........................................................................... 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 590 (290–1,525) 

Phocids ............................................................................ 0 (0–0) 2 (2–3) 0 (0–0) 5 (4–8) 668 (290–1,525) 

1Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. PTS and TTS values depict the range produced by SEL and Peak SPL (as noted) hearing threshold criteria levels. 2Behavioral values depict the ranges produced by RMS hearing threshold criteria levels. 

TABLE 38—RANGE TO EFFECTS (METERS) FROM AIR GUNS FOR 10 PULSES

Range to effects for air guns 1 for 10 pulses (m) 

Hearing group PTS 

(SEL) 

PTS 

(Peak SPL) 

TTS 

(SEL) 

TTS 

(Peak SPL) Behavioral 2

High-Frequency Cetacean ............................................... 0 (0–0) 18 (15–25) 3 (0–9) 33 (25–80) 702 (290–1,525) 

Low-Frequency Cetacean ................................................ 15 (12–20) 2 (2–3) 86 (70–140) 5 (4–7) 651 (200–1,525) 

Mid-Frequency Cetacean ................................................. 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 689 (290–1,525) 

Otariidae ........................................................................... 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 590 (290–1,525) 

Phocids ............................................................................ 0 (0–0) 2 (2–3) 4 (3–5) 5 (4–8) 668 (290–1,525) 

1Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. PTS and TTS values depict the range produced by SEL and Peak SPL (as noted) hearing threshold criteria levels. 2Behavioral values depict the ranges produced by RMS hearing threshold criteria levels. 

Pile Driving 

Table 39 and Table 40 present the 

approximate ranges in meters to PTS, 

TTS, and potential behavioral reactions 

for impact pile driving and vibratory 

pile removal, respectively. Non-auditory 

injury is not predicted for pile driving 

activities. 

TABLE 39—AVERAGE RANGES TO EFFECTS (METERS) FROM IMPACT PILE DRIVING

Hearing group PTS 

(m) 

TTS 

(m) 

Behavioral 

(m) 

Low-frequency Cetaceans ........................................................................................................... 65 529 870 

Mid-frequency Cetaceans ............................................................................................................ 2 16 870 

High-frequency Cetaceans .......................................................................................................... 65 529 870 

Phocids ........................................................................................................................................ 19 151 870 

Otariids ......................................................................................................................................... 2 12 870 

Note: PTS: Permanent threshold shift; TTS: Temporary threshold shift. 

TABLE 40—AVERAGE RANGES TO EFFECT (METERS) FROM VIBRATORY PILE EXTRACTION

Hearing group PTS 

(m) 

TTS 

(m) 

Behavioral 

(m) 

Low-frequency Cetaceans ........................................................................................................... 0 3 376 

Mid-frequency Cetaceans ............................................................................................................ 0 4 376 

High-frequency Cetaceans .......................................................................................................... 7 116 376 

Phocids ........................................................................................................................................ 0 2 376 

Otariids ......................................................................................................................................... 0 0 376 

Note: PTS: Permanent threshold shift; TTS: Temporary threshold shift. 

Serious Injury or Mortality From Ship 

Strikes 

There have been two recorded Navy 

vessel strikes of marine mammals (two 

fin whales off San Diego, CA in 2009) 

in the HSTT Study Area from 2009 

through 2017 (nine years), the period in 

which Navy began implementing 

effective mitigation measures to reduce 

the likelihood of vessel strikes. From 

unpublished NMFS data, the most 

commonly struck whales in Hawaii are 

humpback whales, and the most 

commonly struck whales in California 

are gray whales, fin whales, and 

humpback whales. The majority of these 

strikes are from non-Navy commercial 

shipping. For both areas (Hawaii and 

California), the higher strike rates to 

these species is largely attributed to 


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higher species abundance in these areas. 

Prior to 2009, the Navy had struck 

multiple species of whales off California 

or Hawaii, but also individuals that 

were not identified to species. Further, 

because the overall number of Navy 

strikes is small, it is appropriate to 

consider the larger record of known ship 

strikes (by other types of vessels) in 

predicting what species may potentially 

be involved in a Navy ship strike. Based 

on this information, and as described in 

more detail in Navy’s rulemaking/LOA 

application and below, the Navy 

proposes, and NMFS preliminary 

agrees, to three ship strike takes to select 

large whale species and stocks over the 

five years of the authorization, with no 

more than two takes to several specific 

stocks with a higher likelihood of being 

struck and no more than one take of 

other specific stocks with a lesser 

likelihood of being struck (described in 

detail below in the Vessel Strike 

section). 

Marine Mammal Density 

A quantitative analysis of impacts on 

a species requires data on their 

abundance and distribution that may be 

affected by anthropogenic activities in 

the potentially impacted area. The most 

appropriate metric for this type of 

analysis is density, which is the number 

of animals present per unit area. Marine 

species density estimation requires a 

significant amount of effort to both 

collect and analyze data to produce a 

reasonable estimate. Unlike surveys for 

terrestrial wildlife, many marine species 

spend much of their time submerged, 

and are not easily observed. In order to 

collect enough sighting data to make 

reasonable density estimates, multiple 

observations are required, often in areas 

that are not easily accessible (e.g., far 

offshore). Ideally, marine mammal 

species sighting data would be collected 

for the specific area and time period 

(e.g., season) of interest and density 

estimates derived accordingly. However, 

in many places, poor weather 

conditions and high sea states prohibit 

the completion of comprehensive visual 

surveys. 

For most cetacean species, abundance 

within U.S. waters is estimated using 

line-transect surveys or mark-recapture 

studies (e.g., Barlow, 2010, Barlow and 

Forney, 2007, Calambokidis et al., 

2008). The result provides one single 

density estimate value for each species 

across a broad geographic area. This is 

the general approach applied in 

estimating cetacean abundance in the 

NMFS SARS. Although the single value 

provides a good average estimate of 

abundance (total number of individuals) 

for a specified area, it does not provide 

information on the species distribution 

or concentrations within that area, and 

it does not estimate density for other 

timeframes, areas, or seasons that were 

not surveyed. More recently, habitat 

modeling has been used to estimate 

cetacean densities (e.g., Barlow et al., 

2009; Becker et al., 2010; 2012a; 2014; 

Becker et al., 2016; Ferguson et al., 

2006; Forney et al., 2012; 2015; Redfern 

et al., 2006). These models estimate 

cetacean density as a continuous 

function of habitat variables (e.g., sea 

surface temperature, seafloor depth, 

etc.) and thus allow predictions of 

cetacean densities on finer spatial scales 

than traditional line-transect or mark 

recapture analyses and for areas that 

have not been surveyed. Within the 

geographic area that was modeled, 

densities can be predicted wherever 

these habitat variables can be measured 

or estimated. 

To characterize the marine species 

density for large areas such as the Study 

Area, the Navy compiled data from 

several sources. The Navy developed a 

protocol to select the best available data 

sources based on species, area, and time 

(season). The resulting Geographic 

Information System database called the 

Navy Marine Species Density Database 

includes seasonal density values for 

every marine mammal species present 

within the HSTT Study Area. This 

database is described in the technical 

report titled U.S. Navy Marine Species 

Density Database Phase III for the 

Hawaii-Southern California Training 

and Testing Study Area (U.S. 

Department of the Navy, 2017e), 

hereafter referred to as the Density 

Technical Report. 

A variety of density data and density 

models are needed in order to develop 

a density database that encompasses the 

entirety of the HSTT Study Area. 

Because this data is collected using 

different methods with varying amounts 

of accuracy and uncertainty, the Navy 

has developed a model hierarchy to 

ensure the most accurate data is used 

when available. The Density Technical 

Report describes these models in detail 

and provides detailed explanations of 

the models applied to each species 

density estimate. The below list 

describes models in order of preference. 

1. Spatial density models are 

preferred and used when available 

because they provide an estimate with 

the least amount of uncertainty by 

deriving estimates for divided segments 

of the sampling area. These models (see 

Becker et al., 2016; Forney et al., 2015) 

predict spatial variability of animal 

presence as a function of habitat 

variables (e.g., sea surface temperature, 

seafloor depth, etc.). This model is 

developed for areas, species, and, when 

available, specific timeframes (months 

or seasons) with sufficient survey data. 

2. Stratified designed-based density 

estimates use line-transect survey data 

with the sampling area divided 

(stratified) into sub-regions, and a 

density is predicted for each sub-region 

(see Barlow, 2016; Becker et al., 2016; 

Bradford et al., 2017; Campbell et al., 

2014; Jefferson et al., 2014). While 

geographically stratified density 

estimates provide a better indication of 

a species’ distribution within the study 

area, the uncertainty is typically high 

because each sub-region estimate is 

based on a smaller stratified segment of 

the overall survey effort. 

3. Design-based density estimations 

use line-transect survey data from land 

and aerial surveys designed to cover a 

specific geographic area (see Carretta et 

al., 2015). These estimates use the same 

survey data as stratified design-based 

estimates, but are not segmented into 

sub-regions and instead provide one 

estimate for a large surveyed area. 

Although relative environmental 

suitability (RES) models provide 

estimates for areas of the oceans that 

have not been surveyed using 

information on species occurrence and 

inferred habitat associations and have 

been used in past density databases, 

these models were not used in the 

current quantitative analysis. In the 

HSTT analysis, due to the availability of 

other density methods along the 

hierarchy the use of RES model was not 

necessary. 

When interpreting the results of the 

quantitative analysis, as described in the 

Density Technical Report, ‘‘it is 

important to consider that even the best 

estimate of marine species density is 

really a model representation of the 

values of concentration where these 

animals might occur. Each model is 

limited to the variables and assumptions 

considered by the original data source 

provider. No mathematical model 

representation of any biological 

population is perfect, and with regards 

to marine mammal biodiversity, any 

single model method will not 

completely explain the actual 

distribution and abundance of marine 

mammal species. It is expected that 

there would be anomalies in the results 

that need to be evaluated, with 

independent information for each case, 

to support if we might accept or reject 

a model or portions of the model (U.S. 

Department of the Navy, 2017a).’’ 

The Navy’s estimate of abundance 

(based on the density estimates used) in 

the HSTT Study Area may differ from 

population abundances estimated in the 

NMFS’s SARS for a variety of reasons. 


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Mainly because the Pacific SAR 

overlaps only 35 percent of the Hawaii 

part of HSTT and only about 14 percent 

of SOCAL. The Alaska SAR covering 

humpbacks present in Hawaii is another 

complicating factor. For some species, 

the stock assessment for a given species 

may exceed the Navy’s density 

prediction because those species’ home 

range extends beyond the Study Area 

boundaries. For other species, the stock 

assessment abundance may be much 

less than the number of animals in the 

Navy’s modeling given the HSTT Study 

Area extends well beyond the U.S 

waters covered by the SAR abundance 

estimate. The primary source of density 

estimates are geographically specific 

survey data and either peer-reviewed 

line-transect estimates or habitat-based 

density models that have been 

extensively validated to provide the 

most accurate estimates possible. 

These factors and others described in 

the Density Technical Report should be 

considered when examining the 

estimated impact numbers in 

comparison to current population 

abundance information for any given 

species or stock. For a detailed 

description of the density and 

assumptions made for each species, see 

the Density Technical Report. 

NMFS coordinated with the Navy in 

the development of its take estimates 

and concurs that the Navy’s proposed 

approach for density appropriately 

utilizes the best available science. Later, 

in the Negligible Impact Determination 

Section, we assess how the estimated 

take numbers compare to stock 

abundance in order to better understand 

the potential number of individuals 

impacted—and the rationale for which 

abundance estimate is used is included 

there. 

Take Requests 

The HSTT DEIS/OEIS considered all 

training and testing activities proposed 

to occur in the HSTT Study Area that 

have the potential to result in the 

MMPA defined take of marine 

mammals. The Navy determined that 

the following three stressors could 

result in the incidental taking of marine 

mammals. NMFS has reviewed the 

Navy’s data and analysis and 

determined that it is complete and 

accurate and agrees that the following 

stressors have the potential to result in 

takes of marine mammals from the 

Specified Activities. 

• Acoustics (sonar and other 

transducers; air guns; pile driving/ 

extraction). 

• Explosives (explosive shock wave 

and sound (assumed to encompass the 

risk due to fragmentation). 

• Physical Disturbance and Strike 

(vessel strike). 

Acoustic and explosive sources have 

the potential to result in incidental takes 

of marine mammals by harassment, 

injury, or mortality. Vessel strikes have 

the potential to result in incidental take 

from injury, serious injury and/or 

mortality. 

The quantitative analysis process 

used for the HSTT DEIS/OEIS and the 

Navy’s request in the rulemaking/LOA 

application to estimate potential 

exposures to marine mammals resulting 

from acoustic and explosive stressors is 

detailed in the technical report titled 

Quantifying Acoustic Impacts on 

Marine Mammals and Sea Turtles: 

Methods and Analytical Approach for 

Phase III Training and Testing report 

(U.S. Department of the Navy, 2017b). 

The Navy Acoustic Effects Model 

estimates acoustic and explosive effects 

without taking mitigation into account; 

therefore, the model overestimates 

predicted impacts on marine mammals 

within mitigation zones. To account for 

mitigation for marine species in the take 

estimates, the Navy conducts a 

quantitative assessment of mitigation. 

The Navy conservatively quantifies the 

manner in which mitigation is expected 

to reduce model-estimated PTS to TTS 

for exposures to sonar and other 

transducers, and reduce modelestimated mortality to injury for 

exposures to explosives. The Navy 

assessed the effectiveness of its 

mitigation measures on a per-scenario 

basis for four factors: (1) Species 

sightability, (2) a Lookout’s ability to 

observe the range to PTS (for sonar and 

other transducers) and range to 

mortality (for explosives), (3) the 

portion of time when mitigation could 

potentially be conducted during periods 

of reduced daytime visibility (to include 

inclement weather and high sea-state) 

and the portion of time when mitigation 

could potentially be conducted at night, 

and (4) the ability for sound sources to 

be positively controlled (e.g., powered 

down). 

During the conduct of training and 

testing activities, there is typically at 

least one, if not numerous, support 

personnel involved in the activity (e.g., 

range support personnel aboard a 

torpedo retrieval boat or support 

aircraft). In addition to the Lookout 

posted for the purpose of mitigation, 

these additional personnel observe for 

and disseminate marine species sighting 

information amongst the units 

participating in the activity whenever 

possible as they conduct their primary 

mission responsibilities. However, as a 

conservative approach to assigning 

mitigation effectiveness factors, the 

Navy elected to only account for the 

minimum number of required Lookouts 

used for each activity; therefore, the 

mitigation effectiveness factors may 

underestimate the likelihood that some 

marine mammals may be detected 

during activities that are supported by 

additional personnel who may also be 

observing the mitigation zone. 

The Navy used the equations in the 

below sections to calculate the 

reduction in model-estimated mortality 

impacts due to implementing 

mitigation. 

Equation 1: 

Mitigation Effectiveness = Species 

Sightability × Visibility × 

Observation Area × Positive Control 

Whereas, Species Sightability is the 

ability to detect marine mammals is 

dependent on the animal’s presence at 

the surface and the characteristics of the 

animal that influence its sightability. 

The Navy considered applicable data 

from the best available science to 

numerically approximate the 

sightability of marine mammals and 

determined that the standard ‘‘detection 

probability’’ referred to as g(0). Also, 

Visibility = 1¥sum of individual 

visibility reduction factors; Observation 

Area = portion of impact range that can 

be continuously observed during an 

event; and Positive Control = positive 

control factor of all sound sources 

involving mitigation. For further details 

on these mitigation effectiveness factors 

please refer to the technical report titled 

Quantifying Acoustic Impacts on 

Marine Mammals and Sea Turtles: 

Methods and Analytical Approach for 

Phase III Training and Testing report 

(U.S. Department of the Navy, 2017b). 

To quantify the number of marine 

mammals predicted to be sighted by 

Lookouts during implementation of 

mitigation in the range to injury (PTS) 

for sonar and other transducers, the 

species sightability is multiplied by the 

mitigation effectiveness scores and 

number of model-estimated PTS 

impacts, as shown in the equation 

below: 

Equation 2: 

Number of Animals Sighted by Lookouts 

= Mitigation Effectiveness × ModelEstimated Impacts 

The marine mammals sighted by 

Lookouts during implementation of 

mitigation in the range to PTS, as 

calculated by the equation above, would 

avoid being exposed to these higher 

level impacts. The Navy corrects the 

category of predicted impact for the 

number of animals sighted within the 

mitigation zone (e.g., shifts PTS to TTS), 

but does not modify the total number of 


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animals predicted to experience impacts 

from the scenario. 

To quantify the number of marine 

mammals predicted to be sighted by 

Lookouts during implementation of 

mitigation in the range to mortality 

during events using explosives, the 

species sightability is multiplied by the 

mitigation effectiveness scores and 

number of model-estimated mortality 

impacts, as shown in equation 1 above. 

The marine mammals and sea turtles 

predicted to be sighted by Lookouts 

during implementation of mitigation in 

the range to mortality, as calculated by 

the above equation 2, are predicted to 

avoid exposure in these ranges. The 

Navy corrects the category of predicted 

impact for the number of animals 

sighted within the mitigation zone, but 

does not modify the total number of 

animals predicted to experience impacts 

from the scenario. For example, the 

number of animals sighted (i.e., number 

of animals that will avoid mortality) is 

first subtracted from the modelpredicted mortality impacts, and then 

added to the model-predicted injurious 

impacts. 

NMFS coordinated with the Navy in 

the development of this quantitative 

method to address the effects of 

mitigation on acoustic exposures and 

explosive takes, and NMFS concurs 

with the Navy that it is appropriate to 

incorporate into the take estimates 

based on the best available science. For 

additional information on the 

quantitative analysis process and 

mitigation measures, refer to the 

technical report titled Quantifying 

Acoustic Impacts on Marine Mammals 

and Sea Turtles: Methods and 

Analytical Approach for Phase III 

Training and Testing report (U.S. 

Department of the Navy, 2017b) and 

Section 6 (Take Estimates for Marine 

Mammals) and Section 11 (Mitigation 

Measures) of the Navy’s rulemaking/ 

LOA application. 

Summary of Proposed Authorized Take 

From Training and Testing Activities 

Based on the methods outlined in the 

previous sections and the Navy’s model 

and the quantitative assessment of 

mitigation, the Navy summarizes the 

take request for acoustic and explosive 

sources for training and testing activities 

both annually (based on the maximum 

number of activities per 12-month 

period) and over a 5-year period. NMFS 

has reviewed the Navy’s data and 

analysis and preliminary determined 

that it is complete and accurate and that 

the takes by harassment proposed for 

authorization are reasonably expected to 

occur and that the takes by mortality 

could occur as in the case of vessel 

strikes. Five-year total impacts may be 

less than the sum total of each year 

because although the annual estimates 

are based on the maximum estimated 

takes, five-year estimates are based on 

the sum of two maximum years and 

three nominal years. 

Nonlethal Take Reasonably Expected To 

Occur From Training Activities 

Table 41 summarizes the Navy’s take 

request and the amount and type of take 

that is reasonably likely to occur (Level 

A and Level B harassment) by species 

associated with all training activities. 

Note that Level B harassment take 

includes both behavioral disruption and 

TTS. Figures 6–12 through 6–50 in 

Section 6 of the Navy’s rulemaking/LOA 

application illustrate the comparative 

amounts of TTS and behavioral 

disruption (at the level of a take) for 

each species, noting that if a ‘‘taken’’ 

animat was exposed to both TTS and 

behavioral disruption in the model, it 

was recorded as a TTS. 

TABLE 41—SPECIES-SPECIFIC PROPOSED TAKE AUTHORIZATION FOR ACOUSTIC AND EXPLOSIVE EFFECTS FOR ALL

TRAINING ACTIVITIES IN THE HSTT STUDY AREA

Species Stock 

Annual 5-Year total ** 

Level B Level A Level B Level A 

Suborder Mysticeti (baleen whales) 

Family Balaenopteridae (rorquals) 

Blue whale * ...................................... Central North Pacific ........................ 34 0 139 0 

Eastern North Pacific ....................... 1,155 1 5,036 3 

Bryde’s whale † ................................. Eastern Tropical Pacific ................... 27 0 118 0 

Hawaiian † ........................................ 105 0 429 0 

Fin whale * ......................................... California, Oregon, and Washington 1,245 0 5,482 0 

Hawaiian ........................................... 33 0 133 0 

Humpback whale † ............................ California, Oregon, and Washington †.1,254 1 5,645 3 

Central North Pacific ........................ 5,604 1 23,654 5 

Minke whale ...................................... California, Oregon, and Washington 649 1 2,920 4 

Hawaiian ........................................... 3,463 1 13,664 2 

Sei whale * ........................................ Eastern North Pacific ....................... 53 0 236 0 

Hawaiian ........................................... 118 0 453 0 

Family Eschrichtiidae 

Gray whale † ..................................... Eastern North Pacific ....................... 2,751 5 11,860 19 

Western North Pacific † .................... 4 0 14 0 

Suborder Odontoceti (toothed whales) 

Family Physeteridae (sperm whale) 

Sperm whale * ................................... California, Oregon, and Washington 1,397 0 6,257 0 

Hawaiian ........................................... 1,714 0 7,078 0 

Family Kogiidae (sperm whales) 

Dwarf sperm whale ........................... Hawaiian ........................................... 13,961 35 57,571 148 


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TABLE 41—SPECIES-SPECIFIC PROPOSED TAKE AUTHORIZATION FOR ACOUSTIC AND EXPLOSIVE EFFECTS FOR ALL

TRAINING ACTIVITIES IN THE HSTT STUDY AREA—Continued 

Species Stock 

Annual 5-Year total ** 

Level B Level A Level B Level A 

Pygmy sperm whale ......................... Hawaiian ........................................... 5,556 16 22,833 64 

Kogia whales ..................................... California, Oregon, and Washington 6,012 23 27,366 105 

Family Ziphiidae (beaked whales) 

Baird’s beaked whale ........................ California, Oregon, and Washington 1,317 0 6,044 0 

Blainville’s beaked whale .................. Hawaiian ........................................... 3,687 0 16,364 0 

Cuvier’s beaked whale ...................... California, Oregon, and Washington 6,965 0 32,185 0 

Hawaiian ........................................... 1,235 0 5,497 0 

Longman’s beaked whale ................. Hawaiian ........................................... 13,010 0 57,172 0 

Mesoplodon spp ................................ California, Oregon, and Washington 3,750 0 17,329 0 

Family Delphinidae (dolphins) 

Bottlenose dolphin ............................ California Coastal ............................. 214 0 876 0 

California, Oregon, and Washington 

Offshore.

31,986 2 142,966 9 

Hawaiian Pelagic .............................. 2,086 0 9,055 0 

Kauai & Niihau ................................. 74 0 356 0 

Oahu ................................................. 8,186 1 40,918 5 

4-Island ............................................. 152 0 750 0 

Hawaii ............................................... 42 0 207 0 

False killer whale † ............................ Hawaii Pelagic .................................. 701 0 3,005 0 

Main Hawaiian Islands Insular† ....... 405 0 1,915 0 

Northwestern Hawaiian Islands ....... 256 0 1,094 0 

Fraser’s dolphin ................................ Hawaiian ........................................... 28,409 1 122,784 3 

Killer whale ........................................ Eastern North Pacific Offshore ........ 73 0 326 0 

Eastern North Pacific Transient/ 

West Coast Transient.

135 0 606 0 

Hawaiian ........................................... 84 0 352 0 

Long-beaked common dolphin ......... California .......................................... 128,994 14 559,540 69 

Melon-headed whale ......................... Hawaiian Islands .............................. 2,335 0 9,705 0 

Kohala Resident ............................... 182 0 913 0 

Northern right whale dolphin California, Oregon, and Washington 56,820 8 253,068 40 

Pacific white-sided dolphin ............... California, Oregon, and Washington 43,914 3 194,882 12 

Pantropical spotted dolphin .............. Hawaii Island .................................... 2,585 0 12,603 0 

Hawaii Pelagic .................................. 6,809 0 29,207 0 

Oahu ................................................. 4,127 0 20,610 0 

4-Island ............................................. 260 0 1,295 0 

Pygmy killer whale ............................ Hawaiian ........................................... 5,816 0 24,428 0 

Tropical ............................................. 471 0 2,105 0 

Risso’s dolphin .................................. California, Oregon, and Washington 76,276 6 338,560 30 

Hawaiian ........................................... 6,590 0 28,143 0 

Rough-toothed dolphin ...................... Hawaiian ........................................... 4,292 0 18,506 0 

NSD 1 ................................................ 0 0 0 0 

Short-beaked common dolphin ......... California, Oregon, and Washington 932,453 46 4,161,283 222 

Short-finned pilot whale .................... California, Oregon, and Washington 990 1 4,492 5 

Hawaiian ........................................... 8,594 0 37,077 0 

Spinner dolphin ................................. Hawaii Island .................................... 89 0 433 0 

Hawaii Pelagic .................................. 3,138 0 12,826 0 

Kauai & Niihau ................................. 310 0 1,387 0 

Oahu & 4-Island ............................... 1,493 1 7,445 5 

Striped dolphin .................................. California, Oregon, and Washington 119,219 1 550,936 3 

Hawaiian ........................................... 5,388 0 22,526 0 

Family Phocoenidae (porpoises) 

Dall’s porpoise .................................. California, Oregon, and Washington 27,282 137 121,236 634 

Suborder Pinnipedia 

Family Otariidae (eared seals) 

California sea lion ............................. U.S ................................................... 69,543 91 327,136 455 

Guadalupe fur seal * ......................... Mexico .............................................. 518 0 2,386 0 

Northern fur seal ............................... California .......................................... 9,786 0 44,017 0 

Family Phocidae (true seals) 

Harbor seal ....................................... California .......................................... 3,119 7 13,636 34 


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TABLE 41—SPECIES-SPECIFIC PROPOSED TAKE AUTHORIZATION FOR ACOUSTIC AND EXPLOSIVE EFFECTS FOR ALL

TRAINING ACTIVITIES IN THE HSTT STUDY AREA—Continued 

Species Stock 

Annual 5-Year total ** 

Level B Level A Level B Level A 

Hawaiian monk seal * ........................ Hawaiian ........................................... 139 1 662 3 

Northern elephant seal ..................... California .......................................... 38,169 72 170,926 349 

* ESA-listed species (all stocks) within the HSTT Study Area. 

** 5-year total impacts may be less than sum total of each year. Not all activities occur every year; some activities occur multiple times within a 

year; and some activities only occur a few times over course of a 5-year period. 

† Only designated stocks are ESA-listed. 

1 NSD: No stock designation. 

Nonlethal Take Reasonably Expected To 

Occur From Testing Activities 

Table 42 summarizes the Navy’s take 

request and the amount and type of take 

that is reasonably likely to occur (Level 

A and Level B harassment) by species 

associated with all testing activities. 

Note that Level B harassment take 

includes both behavioral disruption and 

TTS. Figures 6–12 through 6–50 in 

Section 6 of the Navy’s rulemaking/LOA 

application illustrate the comparative 

amounts of TTS and behavioral 

disruption (at the level of a take) for 

each species, noting that if a ‘‘taken’’ 

animat was exposed to both TTS and 

behavioral disruption in the model, it 

was recorded as a TTS. 

TABLE 42—SPECIES-SPECIFIC PROPOSED TAKE AUTHORIZATION FOR ACOUSTIC AND EXPLOSIVE SOUND SOURCE

EFFECTS FOR ALL TESTING ACTIVITIES IN THE HSTT STUDY AREA

Species Stock 

Annual 5-Year total ** 

Level B Level A Level B Level A 

Suborder Mysticeti (baleen whales) 

Family Balaenopteridae (rorquals) 

Blue whale * ...................................... Central North Pacific ........................ 14 0 65 0 

Eastern North Pacific ....................... 833 0 4,005 0 

Bryde’s whale † ................................. Eastern Tropical Pacific ................... 14 0 69 0 

Hawaiian † ........................................ 41 0 194 0 

Fin whale * ......................................... California, Oregon, and Washington 980 1 4,695 3 

Hawaiian ........................................... 15 0 74 0 

Humpback whale † ............................ California, Oregon, and Washington †.740 0 3,508 0 

Central North Pacific ........................ 3,522 2 16,777 10 

Minke whale ...................................... California, Oregon, and Washington 276 0 1,309 0 

Hawaiian ........................................... 1,467 1 6,918 4 

Sei whale * ........................................ Eastern North Pacific ....................... 26 0 124 0 

Hawaiian ........................................... 49 0 229 0 

Family Eschrichtiidae 

Gray whale † ..................................... Eastern North Pacific ....................... 1,920 2 9,277 7 

Western North Pacific † .................... 2 0 11 0 

Suborder Odontoceti (toothed whales) 

Family Physeteridae (sperm whale) 

Sperm whale * ................................... California, Oregon, and Washington 1,096 0 5,259 0 

Hawaiian ........................................... 782 0 3,731 0 

Family Kogiidae (sperm whales) 

Dwarf sperm whale ........................... Hawaiian ........................................... 6,459 29 30,607 140 

Pygmy sperm whale ......................... Hawaiian ........................................... 2,595 13 12,270 60 

Kogia whales ..................................... California, Oregon, and Washington 3,120 15 14,643 67 

Family Ziphiidae (beaked whales) 

Baird’s beaked whale ........................ California, Oregon, and Washington 727 0 3,418 0 

Blainville’s beaked whale .................. Hawaiian ........................................... 1,698 0 8,117 0 

Cuvier’s beaked whale ...................... California, Oregon, and Washington 4,461 0 20,919 0 

Hawaiian ........................................... 561 0 2,675 0 

Longman’s beaked whale ................. Hawaiian ........................................... 6,223 0 29,746 0 

Mesoplodon spp ................................ California, Oregon, and Washington 2,402 0 11,262 0 


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TABLE 42—SPECIES-SPECIFIC PROPOSED TAKE AUTHORIZATION FOR ACOUSTIC AND EXPLOSIVE SOUND SOURCE

EFFECTS FOR ALL TESTING ACTIVITIES IN THE HSTT STUDY AREA—Continued 

Species Stock 

Annual 5-Year total ** 

Level B Level A Level B Level A 

Family Delphinidae (dolphins) 

Bottlenose dolphin ............................ California Coastal ............................. 1,595 0 7,968 0 

California, Oregon, and Washington 

Offshore.

23,436 1 112,410 4 

Hawaiian Pelagic .............................. 1,242 0 6,013 0 

Kauai & Niihau ................................. 491 0 2,161 0 

Oahu ................................................. 475 0 2,294 0 

4-Island ............................................. 207 0 778 0 

Hawaii ............................................... 38 0 186 0 

False killer whale † ............................ Hawaii Pelagic .................................. 340 0 1,622 0 

Main Hawaiian Islands Insular † ...... 184 0 892 0 

Northwestern Hawaiian Islands ....... 125 0 594 0 

Fraser’s dolphin ................................ Hawaiian ........................................... 12,664 1 60,345 5 

Killer whale ........................................ Eastern North Pacific Offshore ........ 34 0 166 0 

Eastern North Pacific Transient/ 

West Coast Transient.

64 0 309 0 

Hawaiian ........................................... 40 0 198 0 

Long-beaked common dolphin ......... California .......................................... 118,278 6 568,020 24 

Melon-headed whale ......................... Hawaiian Islands .............................. 1,157 0 5,423 0 

Kohala Resident ............................... 168 0 795 0 

Northern right whale dolphin ............. California, Oregon, and Washington 41,279 3 198,917 15 

Pacific white-sided dolphin ............... California, Oregon, and Washington 31,424 2 151,000 8 

Pantropical spotted dolphin .............. Hawaii Island .................................... 1,409 0 6,791 0 

Hawaii Pelagic .................................. 3,640 0 17,615 0 

Oahu ................................................. 202 0 957 0 

4-Island ............................................. 458 0 1,734 0 

Pygmy killer whale ............................ Hawaiian ........................................... 2,708 0 13,008 0 

Tropical ............................................. 289 0 1,351 0 

Risso’s dolphin .................................. California, Oregon, and Washington 49,985 3 240,646 15 

Hawaiian ........................................... 2,808 0 13,495 0 

Rough-toothed dolphin ...................... Hawaiian ........................................... 2,193 0 10,532 0 

NSD 1 ................................................ 0 0 0 0 

Short-beaked common dolphin ......... California, Oregon, and Washington 560,120 45 2,673,431 222 

Short-finned pilot whale .................... California, Oregon, and Washington 923 0 4,440 0 

Hawaiian ........................................... 4,338 0 20,757 0 

Spinner dolphin ................................. Hawaii Island .................................... 202 0 993 0 

Hawaii Pelagic .................................. 1,396 0 6,770 0 

Kauai & Niihau ................................. 1,436 0 6,530 0 

Oahu & 4-Island ............................... 331 0 1,389 0 

Striped dolphin .................................. California, Oregon, and Washington 56,035 2 262,973 10 

Hawaiian ........................................... 2,396 0 11,546 0 

Family Phocoenidae (porpoises) 

Dall’s porpoise .................................. California, Oregon, and Washington 17,091 72 81,611 338 

Suborder Pinnipedia 

Family Otariidae (eared seals) 

California sea lion ............................. U.S. .................................................. 48,665 6 237,870 23 

Guadalupe fur seal * ......................... Mexico .............................................. 939 0 4,357 0 

Northern fur seal ............................... California .......................................... 5,505 1 26,168 4 

Family Phocidae (true seals) 

Harbor seal ....................................... California .......................................... 2,325 1 11,258 5 

Hawaiian monk seal * ........................ Hawaiian ........................................... 66 0 254 0 

Northern elephant seal ..................... California .......................................... 22,702 27 107,343 131 

* ESA-listed species (all stocks) within the HSTT Study Area. 

** 5-year total impacts may be less than sum total of each year. Not all activities occur every year; some activities occur multiple times within a 

year; and some activities only occur a few times over course of a 5-year period. 

† Only designated stocks are ESA-listed. 

1 NSD: No stock designation. 


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Take From Vessel Strikes and 

Explosives by Serious Injury or 

Mortality 

Vessel Strike 

A detailed analysis for vessel strike is 

contained in Chapters 5 and 6 the 

Navy’s rulemaking/LOA application. 

Vessel strike to marine mammals is not 

associated with any specific training or 

testing activity but rather is a limited, 

sporadic, and incidental result of Navy 

vessel movement within the HSTT 

Study Area. To support the prediction 

of strikes that could occur in the five 

years covered by the rule, the Navy 

calculated probabilities derived from a 

Poisson distribution using ship strike 

data between 2009–2016 in the HSTT 

Study Area, as well as historical at-sea 

days in HSTT from 2009–2016 and 

estimated potential at-sea days for the 

period from 2019 to 2023 to determine 

the probabilities of a specific number of 

strikes (n=0, 1, 2, etc.) over the period 

from 2019 to 2023. The Navy struck two 

whales in 2009 (both fin whales) in the 

HSTT Study Area, and there have been 

no strikes since that time from activities 

in the HSTT study area that would be 

covered by these regulations. The Navy 

used those two fin whale strikes in their 

calculations and evaluated data 

beginning in 2009 as that was the start 

of the Navy’s Marine Species Awareness 

Training and adoption of additional 

mitigation measures to address ship 

strike. However, there have been no 

incidents of vessel strikes between June 

2009 and April 2018 from HSTT Study 

Area activities. Based on the resulting 

probabilities presented in the Navy’s 

analysis, there is a 10 percent chance of 

three strikes over the period from 2019 

to 2023. Therefore, the Navy estimates, 

and NMFS agrees, that there is some 

probability that it could strike, and take 

by serious injury or mortality, up to 

three large whales incidental to training 

and testing activities within the HSTT 

Study Area over the course of the five 

years. 

The Navy then refined its take request 

based on the species/stocks most likely 

to be present in the HSTT Study Area 

based on documented abundance and 

where overlap is between a species’ 

common occurrence and core Navy 

training and testing areas within the 

HSTT Study Area. To determine which 

species may be struck, a weight of 

evidence approach was used to 

qualitatively rank range complex 

specific species using historic and 

current stranding data from NMFS, 

relative abundance as derived by NMFS 

for the HSTT Phase II Biological 

Opinion, and the Navy funded 

monitoring within each range complex. 

Results of this approach are presented 

in Table 5–4 of the Navy’s rulemaking/ 

LOA application. 

The Navy anticipates, and NMFS 

preliminarily concurs, based on the 

Navy’s ship strike analysis presented in 

the Navy’s rulemaking/LOA application, 

that three vessel strikes could occur 

over the course of five years, and that 

no more than two would involve (and 

therefore the Navy is requesting no more 

than two lethal takes from) the 

following species and stocks: 

• Gray whale (Eastern North Pacific 

stock); 

• Fin whale (California, Oregon, 

Washington stock); 

• Humpback whale (California, 

Oregon, California stock or Mexico 

DPS); 

• Humpback whale (Central Pacific 

stock or Hawaii DPS); and 

• Sperm whale (Hawaiian stock). 

Of the possibility for three vessel 

strikes over the five years, no more than 

one would involve the species below; 

therefore, the Navy is requesting no 

more than one lethal take from) the 

following species and stocks: 

• Blue whale (Eastern North Pacific 

stock); 

• Bryde’s whale (Eastern Tropical 

Pacific stock); 

• Bryde’s whale (Hawaiian stock); 

• Humpback whale (California, 

Oregon, California stock or Central 

America DPS); 

• Minke whale (California, Oregon, 

Washington stock); 

• Minke whale (Hawaiian stock); 

• Sperm whale (California, Oregon, 

Washington stock); 

• Sei whale (Hawaiian stock); and 

• Sei whale (Eastern North Pacific 

stock). 

Vessel strikes to the stocks below are 

very unlikely to occur due to their 

relatively low occurrence in the Study 

Area, particularly in core HSTT training 

and testing subareas, and therefore the 

Navy is not requesting lethal take 

authorization for the following species 

and stocks: 

• Blue whale (Central North Pacific 

stock); 

• Fin whale (Hawaiian stock); and 

• Gray whale (Western North Pacific 

stock). 

Explosives 

The Navy’s model and quantitative 

analysis process used for the HSTT 

DEIS/OEIS and in the Navy’s 

rulemaking/LOA application to estimate 

potential exposures of marine mammals 

to explosive stressors is detailed in the 

technical report titled Quantifying 

Acoustic Impacts on Marine Mammals 

and Sea Turtles: Methods and 

Analytical Approach for Phase III 

Training and Testing report (U.S. 

Department of the Navy, 2017b). 

Specifically, over the course of a year, 

the Navy’s model and quantitative 

analysis process estimates mortality of 

two short-beaked common dolphin and 

one California sea lion as a result of 

exposure to explosive training and 

testing activities (please refer to section 

6 of the Navy’s rule making/LOA 

application). Over the 5-year period of 

the regulations being requested, 

mortality of 10 marine mammals in total 

(6 short-beaked common dolphins and 4 

California sea lions) is estimated as a 

result of exposure to explosive training 

and testing activities. NMFS 

coordinated with the Navy in the 

development of their take estimates and 

concurs with the Navy’s proposed 

approach for estimating the number of 

animals from each species that could be 

affected by mortality takes from 

explosives. 

Proposed Mitigation Measures 

Under section 101(a)(5)(A) of the 

MMPA, NMFS must set forth the 

‘‘permissible methods of taking 

pursuant to such activity, and other 

means of effecting the least practicable 

adverse impact on such species or stock 

and its habitat, paying particular 

attention to rookeries, mating grounds, 

and areas of similar significance, and on 

the availability of such species or stock 

for subsistence uses’’ (‘‘least practicable 

adverse impact’’). NMFS does not have 

a regulatory definition for least 

practicable adverse impact. The NDAA 

for FY 2004 amended the MMPA as it 

relates to military readiness activities 

and the incidental take authorization 

process such that a determination of 

‘‘least practicable adverse impact’’ shall 

include consideration of personnel 

safety, practicality of implementation, 

and impact on the effectiveness of the 

‘‘military readiness activity.’’ 

In Conservation Council for Hawaii v. 

National Marine Fisheries Service, 97 F. 

Supp.3d 1210, 1229 (D. Haw. 2015), the 

Court stated that NMFS ‘‘appear[s] to 

think [it] satisf[ies] the statutory ‘least 

practicable adverse impact’ requirement 

with a ‘negligible impact’ finding.’’ 

More recently, expressing similar 

concerns in a challenge to a U.S. Navy 

Operations of Surveillance Towed Array 

Sensor System Low Frequency Active 

Sonar (SURTASS LFA) incidental take 

rule (77 FR 50290), the Ninth Circuit 

Court of Appeals in Natural Resources 

Defense Council (NRDC) v. Pritzker, 828 

F.3d 1125, 1134 (9th Cir. 2016), stated, 

‘‘[c]ompliance with the ‘negligible 

impact’ requirement does not mean 

there [is] compliance with the ‘least 


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2A growth rate can be positive, negative, or flat. 

3For purposes of this discussion we omit 

reference to the language in the standard for least 

practicable adverse impact that says we also must 

mitigate for subsistence impacts because they are 

not at issue in this rule. 

4Outside of the military readiness context, 

mitigation may also be appropriate to ensure 

compliance with the ‘‘small numbers’’ language in 

MMPA sections 101(a)(5)(A) and (D). 

practicable adverse impact’ standard.’’ 

As the Ninth Circuit noted in its 

opinion, however, the Court was 

interpreting the statute without the 

benefit of NMFS’s formal interpretation. 

We state here explicitly that NMFS is in 

full agreement that the ‘‘negligible 

impact’’ and ‘‘least practicable adverse 

impact’’ requirements are distinct, even 

though both statutory standards refer to 

species and stocks. With that in mind, 

we provide further explanation of our 

interpretation of least practicable 

adverse impact, and explain what 

distinguishes it from the negligible 

impact standard. This discussion is 

consistent with, and expands upon, 

previous rules we have issued (such as 

the Navy Gulf of Alaska rule (82 FR 

19530; April 27, 2017)). 

Before NMFS can issue incidental 

take regulations under section 

101(a)(5)(A) of the MMPA, it must make 

a finding that the total taking will have 

a ‘‘negligible impact’’ on the affected 

‘‘species or stocks’’ of marine mammals. 

NMFS’s and U.S. Fish and Wildlife 

Service’s implementing regulations for 

section 101(a)(5) both define ‘‘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 and 50 CFR 18.27(c)). 

Recruitment (i.e., reproduction) and 

survival rates are used to determine 

population growth rates 2 and, therefore 

are considered in evaluating population 

level impacts. 

As we stated in the preamble to the 

final rule for the incidental take 

implementing regulations, not every 

population-level impact violates the 

negligible impact requirement. The 

negligible impact standard does not 

require a finding that the anticipated 

take will have ‘‘no effect’’ on population 

numbers or growth rates: ‘‘The statutory 

standard does not require that the same 

recovery rate be maintained, rather that 

no significant effect on annual rates of 

recruitment or survival occurs. [T]he 

key factor is the significance of the level 

of impact on rates of recruitment or 

survival.’’ (54 FR 40338, 40341–42; 

September 29, 1989). 

While some level of impact on 

population numbers or growth rates of 

a species or stock may occur and still 

satisfy the negligible impact 

requirement—even without 

consideration of mitigation—the least 

practicable adverse impact provision 

separately requires NMFS to prescribe 

means of ‘‘effecting the least practicable 

adverse impact on such species or stock 

and its habitat, paying particular 

attention to rookeries, mating grounds, 

and areas of similar significance’’ 50 

CFR 216.102(b), which are typically 

identified as mitigation measures.3

The negligible impact and least 

practicable adverse impact standards in 

the MMPA both call for evaluation at 

the level of the ‘‘species or stock.’’ The 

MMPA does not define the term 

‘‘species.’’ However, Merriam-Webster 

Dictionary defines ‘‘species’’ to include 

‘‘related organisms or populations 

potentially capable of interbreeding.’’ 

See www.merriam-webster.com/ 

dictionary/species (emphasis added). 

The MMPA defines ‘‘stock’’ as ‘‘a group 

of marine mammals of the same species 

or smaller taxa in a common spatial 

arrangement that interbreed when 

mature.’’ 16 U.S.C. 1362(11). The 

definition of ‘‘population’’ is ‘‘a group of 

interbreeding organisms that represents 

the level of organization at which 

speciation begins.’’ www.merriamwebster.com/dictionary/population. The 

definition of ‘‘population’’ is strikingly 

similar to the MMPA’s definition of 

‘‘stock,’’ with both involving groups of 

individuals that belong to the same 

species and located in a manner that 

allows for interbreeding. In fact, the 

term ‘‘stock’’ in the MMPA is 

interchangeable with the statutory term 

‘‘population stock.’’ 16 U.S.C. 1362(11). 

Thus, the MMPA terms ‘‘species’’ and 

‘‘stock’’ both relate to populations, and 

it is therefore appropriate to view both 

the negligible impact standard and the 

least practicable adverse impact 

standard, both of which call for 

evaluation at the level of the species or 

stock, as having a population-level 

focus. 

This interpretation is consistent with 

Congress’s statutory findings for 

enacting the MMPA, nearly all of which 

are most applicable at the species or 

stock (i.e., population) level. See 16 

U.S.C. 1361 (finding that it is species 

and population stocks that are or may be 

in danger of extinction or depletion; that 

it is species and population stocks that 

should not diminish beyond being 

significant functioning elements of their 

ecosystems; and that it is species and 

population stocks that should not be 

permitted to diminish below their 

optimum sustainable population level). 

Annual rates of recruitment (i.e., 

reproduction) and survival are the key 

biological metrics used in the evaluation 

of population-level impacts, and 

accordingly these same metrics are also 

used in the evaluation of population 

level impacts for the least practicable 

adverse impact standard. 

Recognizing this common focus of the 

least practicable adverse impact and 

negligible impact provisions on the 

‘‘species or stock’’ does not mean we 

conflate the two standards; despite some 

common statutory language, we 

recognize the two provisions are 

different and have different functions. 

First, a negligible impact finding is 

required before NMFS can issue an 

incidental take authorization. Although 

it is acceptable to use the mitigation 

measures to reach a negligible impact 

finding (see 50 CFR 216.104(c)), no 

amount of mitigation can enable NMFS 

to issue an incidental take authorization 

for an activity that still would not meet 

the negligible impact standard. 

Moreover, even where NMFS can reach 

a negligible impact finding—which we 

emphasize does allow for the possibility 

of some ‘‘negligible’’ population-level 

impact—the agency must still prescribe 

measures that will affect the least 

practicable amount of adverse impact 

upon the affected species or stock. 

Section 101(a)(5)(A)(i)(II) requires 

NMFS to issue, in conjunction with its 

authorization, binding—and 

enforceable—restrictions (in the form of 

regulations) setting forth how the 

activity must be conducted, thus 

ensuring the activity has the ‘‘least 

practicable adverse impact’’ on the 

affected species or stocks. In situations 

where mitigation is specifically needed 

to reach a negligible impact 

determination, section 101(a)(5)(A)(i)(II) 

also provides a mechanism for ensuring 

compliance with the ‘‘negligible 

impact’’ requirement. Finally, we 

reiterate that the least practicable 

adverse impact standard also requires 

consideration of measures for marine 

mammal habitat, with particular 

attention to rookeries, mating grounds, 

and other areas of similar significance, 

and for subsistence impacts; whereas 

the negligible impact standard is 

concerned solely with conclusions 

about the impact of an activity on 

annual rates of recruitment and 

survival.4

In NRDC v. Pritzker, the Court stated, 

‘‘[t]he statute is properly read to mean 

that even if population levels are not 

threatened significantly, still the agency 

must adopt mitigation measures aimed 

at protecting marine mammals to the 

greatest extent practicable in light of 


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29964 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

military readiness needs.’’ Id. at 1134 

(emphases added). This statement is 

consistent with our understanding 

stated above that even when the effects 

of an action satisfy the negligible impact 

standard (i.e., in the Court’s words, 

‘‘population levels are not threatened 

significantly’’), still the agency must 

prescribe mitigation under the least 

practicable adverse impact standard. 

However, as the statute indicates, the 

focus of both standards is ultimately the 

impact on the affected ‘‘species or 

stock,’’ and not solely focused on or 

directed at the impact on individual 

marine mammals. 

We have carefully reviewed and 

considered the Ninth Circuit’s opinion 

in NRDC v. Pritzker in its entirety. 

While the Court’s reference to ‘‘marine 

mammals’’ rather than ‘‘marine mammal 

species or stocks’’ in the italicized 

language above might be construed as a 

holding that the least practicable 

adverse impact standard applies at the 

individual ‘‘marine mammal’’ level, i.e., 

that NMFS must require mitigation to 

minimize impacts to each individual 

marine mammal unless impracticable, 

we believe such an interpretation 

reflects an incomplete appreciation of 

the Court’s holding. In our view, the 

opinion as a whole turned on the 

Court’s determination that NMFS had 

not given separate and independent 

meaning to the least practicable adverse 

impact standard apart from the 

negligible impact standard, and further, 

that the Court’s use of the term ‘‘marine 

mammals’’ was not addressing the 

question of whether the standard 

applies to individual animals as 

opposed to the species or stock as a 

whole. We recognize that while 

consideration of mitigation can play a 

role in a negligible impact 

determination, consideration of 

mitigation measures extends beyond 

that analysis. In evaluating what 

mitigation measures are appropriate, 

NMFS considers the potential impacts 

of the Specified Activities, the 

availability of measures to minimize 

those potential impacts, and the 

practicability of implementing those 

measures, as we describe below. 

Implementation of Least Practicable 

Adverse Impact Standard 

Given the NRDC v. Pritzker decision, 

we discuss here how we determine 

whether a measure or set of measures 

meets the ‘‘least practicable adverse 

impact’’ standard. Our separate analysis 

of whether the take anticipated to result 

from Navy’s activities meets the 

‘‘negligible impact’’ standard appears in 

the section ‘‘Preliminary Negligible 

Impact Analysis and Determination’’ 

below. 

Our evaluation of potential mitigation 

measures includes consideration of two 

primary factors: 

(1) The manner in which, and the 

degree to which, implementation of the 

potential measure(s) is expected to 

reduce adverse impacts to marine 

mammal species or stocks, their habitat, 

and their availability for subsistence 

uses (where relevant). This analysis 

considers such things as the nature of 

the potential adverse impact (such as 

likelihood, scope, and range), the 

likelihood that the measure will be 

effective if implemented, and the 

likelihood of successful 

implementation; and 

(2) The practicability of the measures 

for applicant implementation. 

Practicability of implementation may 

consider such things as cost, impact on 

operations, and, in the case of a military 

readiness activity, specifically considers 

personnel safety, practicality of 

implementation, and impact on the 

effectiveness of the military readiness 

activity. 16 U.S.C. 1371(a)(5)(A)(ii). 

While the language of the least 

practicable adverse impact standard 

calls for minimizing impacts to affected 

species or stocks, we recognize that the 

reduction of impacts to those species or 

stocks accrues through the application 

of mitigation measures that limit 

impacts to individual animals. 

Accordingly, NMFS’s analysis focuses 

on measures designed to avoid or 

minimize impacts on marine mammals 

from activities that are likely to increase 

the probability or severity of 

population-level effects. 

While complete information on 

impacts to species or stocks from a 

specified activity is not available for 

every activity type, and additional 

information would help NMFS and the 

Navy better understand how specific 

disturbance events affect the fitness of 

individuals of certain species, there 

have been significant improvements in 

understanding the process by which 

disturbance effects are translated to the 

population. With recent scientific 

advancements (both marine mammal 

energetic research and the development 

of energetic frameworks), the relative 

likelihood or degree of impacts on 

species or stocks may typically be 

predicted given a detailed 

understanding of the activity, the 

environment, and the affected species or 

stocks. This same information is used in 

the development of mitigation measures 

and helps us understand how mitigation 

measures contribute to lessening effects 

to species or stocks. We also 

acknowledge that there is always the 

potential that new information, or a new 

recommendation that we had not 

previously considered, becomes 

available and necessitates reevaluation 

of mitigation measures (which may be 

addressed through adaptive 

management) to see if further reductions 

of population impacts are possible and 

practicable. 

In the evaluation of specific measures, 

the details of the specified activity will 

necessarily inform each of the two 

primary factors discussed above 

(expected reduction of impacts and 

practicability), and are carefully 

considered to determine the types of 

mitigation that are appropriate under 

the least practicable adverse impact 

standard. Analysis of how a potential 

mitigation measure may reduce adverse 

impacts on a marine mammal stock or 

species, consideration of personnel 

safety, practicality of implementation, 

and consideration of the impact on 

effectiveness of military readiness 

activities are not issues that can be 

meaningfully evaluated through a yes/ 

no lens. The manner in which, and the 

degree to which, implementation of a 

measure is expected to reduce impacts, 

as well as its practicability in terms of 

these considerations, can vary widely. 

For example, a time/area restriction 

could be of very high value for 

decreasing population-level impacts 

(e.g., avoiding disturbance of feeding 

females in an area of established 

biological importance) or it could be of 

lower value (e.g., decreased disturbance 

in an area of high productivity but of 

less firmly established biological 

importance). Regarding practicability, a 

measure might involve restrictions in an 

area or time that impede the Navy’s 

ability to certify a strike group (higher 

impact on mission effectiveness), or it 

could mean delaying a small in-port 

training event by 30 minutes to avoid 

exposure of a marine mammal to 

injurious levels of sound (lower impact). 

A responsible evaluation of ‘‘least 

practicable adverse impact’’ will 

consider the factors along these realistic 

scales. Accordingly, the greater the 

likelihood that a measure will 

contribute to reducing the probability or 

severity of adverse impacts to the 

species or stock or their habitat, the 

greater the weight that measure is given 

when considered in combination with 

practicability to determine the 

appropriateness of the mitigation 

measure, and vice versa. In the 

evaluation of specific measures, the 

details of the specified activity will 

necessarily inform each of the two 

primary factors discussed above 

(expected reduction of impacts and 


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5We recognize the least practicable adverse 

impact standard requires consideration of measures 

that will address minimizing impacts on the 

availability of the species or stocks for subsistence 

uses where relevant. Because subsistence uses are 

not implicated for this action we do not discuss 

them. However, a similar framework would apply 

for evaluating those measures, taking into account 

the MMPA’s directive that we make a finding of no 

unmitigable adverse impact on the availability of 

the species or stocks for taking for subsistence, and 

the relevant implementing regulations. 

practicability), and will be carefully 

considered to determine the types of 

mitigation that are appropriate under 

the least practicable adverse impact 

standard. We discuss consideration of 

these factors in greater detail below. 

1. Reduction of adverse impacts to 

marine mammal species or stocks and 

their habitat.5 The emphasis given to a 

measure’s ability to reduce the impacts 

on a species or stock considers the 

degree, likelihood, and context of the 

anticipated reduction of impacts to 

individuals (and how many individuals) 

as well as the status of the species or 

stock. 

The ultimate impact on any 

individual from a disturbance event 

(which informs the likelihood of 

adverse species- or stock-level effects) is 

dependent on the circumstances and 

associated contextual factors, such as 

duration of exposure to stressors. 

Though any proposed mitigation needs 

to be evaluated in the context of the 

specific activity and the species or 

stocks affected, measures with the 

following types of effects have greater 

value in reducing the likelihood or 

severity of adverse species- or stocklevel impacts: Avoiding or minimizing 

injury or mortality; limiting interruption 

of known feeding, breeding, mother/ 

young, or resting behaviors; minimizing 

the abandonment of important habitat 

(temporally and spatially); minimizing 

the number of individuals subjected to 

these types of disruptions; and limiting 

degradation of habitat. Mitigating these 

types of effects is intended to reduce the 

likelihood that the activity will result in 

energetic or other types of impacts that 

are more likely to result in reduced 

reproductive success or survivorship. It 

is also important to consider the degree 

of impacts that are expected in the 

absence of mitigation in order to assess 

the added value of any potential 

measures. Finally, because the least 

practicable adverse impact standard 

gives NMFS discretion to weigh a 

variety of factors when determining 

what should be included as appropriate 

mitigation measures and because the 

focus is on reducing impacts at the 

species or stock level, it does not 

compel mitigation for every kind of 

take, or every individual taken, even 

when practicable for implementation by 

the applicant. 

The status of the species or stock is 

also relevant in evaluating the 

appropriateness of potential mitigation 

measures in the context of least 

practicable adverse impact. The 

following are examples of factors that 

may (either alone, or in combination) 

result in greater emphasis on the 

importance of a mitigation measure in 

reducing impacts on a species or stock: 

The stock is known to be decreasing or 

status is unknown, but believed to be 

declining; the known annual mortality 

(from any source) is approaching or 

exceeding the Potential Biological 

Removal (PBR) level (as defined in 16 

U.S.C. 1362(20)); the affected species or 

stock is a small, resident population; or 

the stock is involved in a UME or has 

other known vulnerabilities, such as 

recovering from an oil spill. 

Habitat mitigation, particularly as it 

relates to rookeries, mating grounds, and 

areas of similar significance, is also 

relevant to achieving the standard and 

can include measures such as reducing 

impacts of the activity on known prey 

utilized in the activity area or reducing 

impacts on physical habitat. As with 

species- or stock-related mitigation, the 

emphasis given to a measure’s ability to 

reduce impacts on a species or stock’s 

habitat considers the degree, likelihood, 

and context of the anticipated reduction 

of impacts to habitat. Because habitat 

value is informed by marine mammal 

presence and use, in some cases there 

may be overlap in measures for the 

species or stock and for use of habitat. 

We consider available information 

indicating the likelihood of any measure 

to accomplish its objective. If evidence 

shows that a measure has not typically 

been effective nor successful, then 

either that measure should be modified 

or the potential value of the measure to 

reduce effects should be lowered. 

2. Practicability. Factors considered 

may include cost, impact on operations, 

and, in the case of a military readiness 

activity, personnel safety, practicality of 

implementation, and impact on the 

effectiveness of the military readiness 

activity (16 U.S.C. 1371(a)(5)(A)(ii)). 

NMFS reviewed the Specified 

Activities and the proposed mitigation 

measures as described in the Navy’s 

rulemaking/LOA application and the 

HSTT DEIS/OEIS to determine if they 

would result in the least practicable 

adverse effect on marine mammals. 

NMFS worked with the Navy in the 

development of the Navy’s initially 

proposed measures, which are informed 

by years of implementation and 

monitoring. A complete discussion of 

the evaluation process used to develop, 

assess, and select mitigation measures, 

which was informed by input from 

NMFS, can be found in Chapter 5 

(Mitigation) and Appendix K 

(Geographic Mitigation Assessment) of 

the HSTT DEIS/OEIS and is 

summarized below. We agree that the 

process described in Chapter 5 and 

Appendix K of the HSTT DEIS/OEIS is 

an accurate and appropriate process for 

evaluating whether the mitigation 

measures proposed in this rule meet the 

least practicable adverse impact 

standard for the testing and training 

activities in this proposed rule. The 

Navy proposes to implement these 

mitigation measures to avoid potential 

impacts from acoustic, explosive, and 

physical disturbance and strike 

stressors. 

In summary (and described in more 

detail below), the Navy proposes 

procedural mitigation measures that we 

find will reduce the probability and/or 

severity of impacts expected to result 

from acute exposure to acoustic sources 

or explosives, ship strike, and impacts 

to marine mammal habitat. Specifically, 

the Navy would use a combination of 

delayed starts, powerdowns, and 

shutdowns to minimize or avoid serious 

injury or mortality, minimize the 

likelihood or severity of PTS or other 

injury, and reduce instances of TTS or 

more severe behavioral disruption 

caused by acoustic sources or 

explosives. The Navy also proposes to 

implement multiple time/area 

restrictions (several of which have been 

added since the Phase II rule) that 

would reduce take of marine mammals 

in areas or at times where they are 

known to engage in important 

behaviors, such as feeding or calving, 

where the disruption of those behaviors 

would have a higher probability of 

resulting in impacts on reproduction or 

survival of individuals that could lead 

to population-level impacts. The Navy 

assessed the practicability of the 

measures it proposed in the context of 

personnel safety, practicality of 

implementation, and their impacts on 

the Navy’s ability to meet their Title 10 

requirements and found that the 

measures were supportable. As 

summarized in this paragraph and 

described in more detail below, NMFS 

has evaluated the measures the Navy 

has proposed in the manner described 

earlier in this section (i.e., in 

consideration of their ability to reduce 

adverse impacts on marine mammal 

species or stocks and their habitat and 

their practicability for implementation) 

and has determined that the measures 

will both significantly and adequately 

reduce impacts on the affected marine 


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mammal species or stocks and their 

habitat and be practicable for Navy 

implementation. Therefore, the 

mitigation measures assure that Navy’s 

activities will have the least practicable 

adverse impact on the species and 

stocks and their habitat. 

The Navy also evaluated numerous 

measures in the Navy’s HSTT DEIS/ 

OEIS that are not included in the Navy’s 

rulemaking/LOA application for the 

Specified Activities, and NMFS 

preliminarily concurs with Navy’s 

analysis that their inclusion was not 

appropriate under the least practicable 

adverse impact standard based on our 

assessment. The Navy considers these 

additional potential mitigation measures 

in two groups. Chapter 5 of the HSTT 

DEIS/OEIS, in the ‘‘Measures 

Considered but Eliminated’’ section, 

includes an analysis of an array of 

different types of mitigation that have 

been recommended over the years by 

NGOs or the public, through scoping or 

public comment on environmental 

compliance documents. Appendix K of 

the HSTT DEIS/OEIS includes an indepth analysis of time/area restrictions 

that have been recommended over time 

or previously implemented as a result of 

litigation. As described in Chapter 5 of 

the DEIS/OEIS, commenters sometimes 

recommend that the Navy reduce their 

overall amount of training, reduce 

explosive use, modify their sound 

sources, completely replace live training 

with computer simulation, or include 

time of day restrictions. All of these 

proposed measures could potentially 

reduce the number of marine mammals 

taken, via direct reduction of the 

activities or amount of sound energy put 

in the water. However, as the Navy has 

described in Chapter 5 of the HSTT 

DEIS/OEIS, they need to train and test 

in the conditions in which they fight— 

and these types of modifications 

fundamentally change the activity in a 

manner that would not support the 

purpose and need for the training and 

testing (i.e., are entirely impracticable) 

and therefore are not considered further. 

NMFS finds the Navy’s explanation for 

why adoption of these 

recommendations would unacceptably 

undermine the purpose of the testing 

and training persuasive. In addition, 

NMFS must rely on Navy’s judgment to 

a great extent on issues such as its 

personnel’s safety, practicability of 

Navy’s implementation, and extent to 

which a potential measure would 

undermine the effectiveness of Navy’s 

testing and training. For these reasons, 

NMFS finds that these measures do not 

meet the least practicable adverse 

impact standard because they are not 

practicable. 

Second in Chapter 5 of the DEIS/ 

OEIS, the Navy evaluated additional 

potential procedural mitigation 

measures, including increased 

mitigation zones, ramp-up measures, 

additional passive acoustic and visual 

monitoring, and decreased vessel 

speeds. Some of these measures have 

the potential to incrementally reduce 

take to some degree in certain 

circumstances, though the degree to 

which this would occur is typically low 

or uncertain. However, as described in 

the Navy’s analysis, the impracticability 

of implementation outweighed the 

potential reduction of impacts to marine 

mammal species or stocks (see Chapter 

5 of HSTT DEIS/OEIS). NMFS reviewed 

the Navy’s evaluation and concurred 

with this assessment that this additional 

mitigation was not warranted. 

Appendix K describes a 

comprehensive method for analyzing 

potential geographic mitigation that 

includes consideration of both a 

biological assessment of how the 

potential time/area limitation would 

benefit the species or stock and its 

habitat (e.g., is a key area of biological 

importance or would result in 

avoidance or reduction of impacts) in 

the context of the stressors of concern in 

the specific area and an operational 

assessment of the practicability of 

implementation (e.g., including an 

assessment of the specific importance of 

that area for training—considering 

proximity to training ranges and 

emergency landing fields and other 

issues). The analysis analyzes an 

extensive list of areas including 

Biologically Important Areas, areas 

agreed to under the HSTT settlement 

agreement, areas identified by the 

California Coastal Commission, and 

areas suggested during scoping. For the 

areas that were agreed to under the 

settlement agreement, the Navy notes 

two important facts that NMFS 

generally concurs with: (1) The 

measures were derived pursuant to 

negotiations with plaintiffs and were 

specifically not evaluated or selected 

based on the examination of the best 

available science that NMFS typically 

applies to a mitigation assessment and; 

(2) the Navy’s adoption of restrictions 

on its activities as part of a relatively 

short-term settlement does not mean 

that those restrictions are practicable to 

implement over the longer term. 

Navy has proposed several time/area 

mitigations that were not included in 

the Phase II HSTT regulations. For the 

areas that are not included in the 

proposed regulations, though, the Navy 

found that on balance, the mitigation 

was not warranted because the 

anticipated reduction of adverse 

impacts on marine mammal species or 

stock and their habitat was not 

sufficient to offset the impracticability 

of implementation (in some cases 

potential benefits to marine mammals 

were limited to non-existent, in others 

the consequences on mission 

effectiveness were too great). NMFS has 

reviewed the Navy’s analysis (Chapter 5 

and Appendix K referenced above), 

which considers the same factors that 

NMFS would consider to satisfy the 

least practical adverse impact standard, 

and has preliminarily concurred with 

the conclusions, and is not proposing to 

include any of the measures that the 

Navy ruled out in the proposed 

regulations. Below are the mitigation 

measures that NMFS determined will 

ensure the least practicable adverse 

impact on all affected species and stocks 

and their habitat, including the specific 

considerations for military readiness 

activities. The following sections 

summarize the mitigation measures that 

will be implemented in association with 

the training and testing activities 

analyzed in this document. The 

mitigation measures are organized into 

two categories: Procedural mitigation 

and mitigation areas. 

Procedural Mitigation 

Procedural mitigation is mitigation 

that the Navy will implement whenever 

and wherever an applicable training or 

testing activity takes place within the 

HSTT Study Area. The Navy customizes 

procedural mitigation for each 

applicable activity category or stressor. 

Procedural mitigation generally 

involves: (1) The use of one or more 

trained Lookouts to diligently observe 

for specific biological resources 

(including marine mammals) within a 

mitigation zone, (2) requirements for 

Lookouts to immediately communicate 

sightings of specific biological resources 

to the appropriate watch station for 

information dissemination, and (3) 

requirements for the watch station to 

implement mitigation (e.g., halt an 

activity) until certain recommencement 

conditions have been met. The first 

procedural mitigation (Table 42) is 

designed to aid Lookouts and other 

applicable personnel with their 

observation, environmental compliance, 

and reporting responsibilities. The 

remainder of the procedural mitigations 

(Tables 43 through Tables 62) are 

organized by stressor type and activity 

category and includes acoustic stressors 

(i.e., active sonar, air guns, pile driving, 

weapons firing noise), explosive 

stressors (i.e., sonobuoys, torpedoes, 

medium-caliber and large-caliber 


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projectiles, missiles and rockets, bombs, 

sinking exercises, mines, underwater 

demolition multiple charge mat weave 

and obstacles loading, anti-swimmer 

grenades), and physical disturbance and 

strike stressors (i.e., vessel movement, 

towed in-water devices, small-, 

medium-, and large-caliber nonexplosive practice munitions, nonexplosive missiles and rockets, nonexplosive bombs and mine shapes). 

TABLE 43—PROCEDURAL MITIGATION FOR ENVIRONMENTAL AWARENESS AND EDUCATION

Procedural mitigation description 

Stressor or Activity: 

• All training and testing activities, as applicable. 

Mitigation Zone Size and Mitigation Requirements: 

• Appropriate personnel involved in mitigation and training or testing activity reporting under the Specified Activities will complete one or 

more modules of the U.S. Navy Afloat Environmental Compliance Training Series, as identified in their career path training plan. Modules 

include: 

• Introduction to the U.S. Navy Afloat Environmental Compliance Training Series. The introductory module provides information on environmental laws (e.g., ESA, MMPA) and the corresponding responsibilities relevant to Navy training and testing. The material explains why environmental compliance is important in supporting the Navy’s commitment to environmental stewardship. 

• Marine Species Awareness Training. All bridge watch personnel, Commanding Officers, Executive Officers, maritime patrol aircraft 

aircrews, anti-submarine warfare and mine warfare rotary-wing aircrews, Lookouts, and equivalent civilian personnel must successfully complete the Marine Species Awareness Training prior to standing watch or serving as a Lookout. The Marine Species Awareness Training provides information on sighting cues, visual observation tools and techniques, and sighting notification procedures. 

Navy biologists developed Marine Species Awareness Training to improve the effectiveness of visual observations for biological resources, focusing on marine mammals and sea turtles, and including floating vegetation, jellyfish aggregations, and flocks of 

seabirds. 

• U.S. Navy Sonar Positional Reporting System and Marine Mammal Incident Reporting. This module provides instruction on the procedures and activity reporting requirements for the Sonar Positional Reporting System and marine mammal incident reporting. 

• U.S. Navy Protective Measures Assessment Protocol. This module provides the necessary instruction for accessing mitigation requirements during the event planning phase using the Protective Measures Assessment Protocol software tool. Also related are annual marine mammal awareness messages promulgated annually to Fleet units: 

For Hawaii: 

• Humpback Whale Awareness Notification Message Area (November 15–April 15): 

—The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including humpback whales. 

—To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to 

remain vigilant to the presence of large whale species (including humpback whales), that when concentrated seasonally, 

may become vulnerable to vessel strikes. 

—Lookouts will use the information from the awareness notification message to assist their visual observation of applicable 

mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. 

For Southern California: 

• Blue Whale Awareness Notification Message Area (June 1–October 31): 

—The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including blue whales. 

—To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to 

remain vigilant to the presence of large whale species (including blue whales), that when concentrated seasonally, may become vulnerable to vessel strikes. 

—Lookouts will use the information from the awareness notification messages to assist their visual observation of applicable 

mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation observation of 

applicable mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. 

• Gray Whale Awareness Notification Message Area (November 1–March 31): 

—The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including gray whales. 

—To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to 

remain vigilant to the presence of large whale species (including gray whales), that when concentrated seasonally, may become vulnerable to vessel strikes. 

—Lookouts will use the information from the awareness notification messages to assist their visual observation of applicable 

mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. 

• Fin Whale Awareness Notification Message Area (November 1–May 31): 

—The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including fin whales. 

—To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to 

remain vigilant to the presence of large whale species (including fin whales), that when concentrated seasonally, may become vulnerable to vessel strikes. 

—Lookouts will use the information from the awareness notification messages to assist their visual observation of applicable 

mitigation zones during training and testing activities and to aid in implementation of procedural mitigation. 

Procedural Mitigation for Acoustic 

Stressors 

Mitigation measures for acoustic 

stressors are provided in Tables 44 

through 47. 

Procedural Mitigation for Active Sonar 

Procedural mitigation for active sonar 

is described in Table 44 below. 


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TABLE 44—PROCEDURAL MITIGATION FOR ACTIVE SONAR

Procedural mitigation description 

Stressor or Activity: 

• Low-frequency active sonar, mid-frequency active sonar, high-frequency active sonar. 

• For vessel-based active sonar activities, mitigation applies only to sources that are positively controlled and deployed from manned surface vessels (e.g., sonar sources towed from manned surface platforms). 

• For aircraft-based active sonar activities, mitigation applies only to sources that are positively controlled and deployed from manned aircraft that do not operate at high altitudes (e.g., rotary-wing aircraft). Mitigation does not apply to active sonar sources deployed from unmanned aircraft or aircraft operating at high altitudes (e.g., maritime patrol aircraft). 

Number of Lookouts and Observation Platform: 

• Hull-mounted sources: 

• Platforms without space or manning restrictions while underway: 2 Lookouts at the forward part of the ship. 

• Platforms with space or manning restrictions while underway: 1 Lookout at the forward part of a small boat or ship 

• Platforms using active sonar while moored or at anchor (including pierside): 1 Lookout 

• Sources that are not hull-mounted: 

• 1 Lookout on the ship or aircraft conducting the activity. 

Mitigation Zone Size and Mitigation Requirements: 

• Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource is 

observed, do not commence use of active sonar. 

• Low-frequency active sonar at 200 dB or more, and hull-mounted mid-frequency active sonar will implement the following mitigation 

zones: 

• During the activity, observe for marine mammals; power down active sonar transmission by 6 dB if resource is observed within 1,000 

yd of the sonar source; power down by an additional 4 dB (10 dB total) if resource is observed within 500 yd of the sonar source; 

and cease transmission if resource is observed within 200 yd of the sonar source. 

• Low-frequency active sonar below 200 dB, mid-frequency active sonar sources that are not hull-mounted, and high-frequency active 

sonar will implement the following mitigation zone: 

• During the activity, observe for marine mammals; cease active sonar transmission if resource is observed within 200 yd of the sonar 

source. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence active sonar transmission until one of 

the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have 

exited the mitigation zone based on a determination of its course, speed, and movement relative to the sonar source; (3) the mitigation 

zone has been clear from any additional sightings for 10 min for aircraft-deployed sonar sources or 30 min for vessel-deployed sonar 

sources; (4) for mobile activities, the active sonar source has transited a distance equal to double that of the mitigation zone size beyond 

the location of the last sighting; or (5) for activities using hull-mounted sonar, the Lookout concludes that dolphins are deliberately closing 

in on the ship to ride the ship’s bow wave, and are therefore out of the main transmission axis of the sonar (and there are no other marine mammal sightings within the mitigation zone). 

Procedural Mitigation for Air Guns 

Procedural mitigation for air guns is 

described in Table 45 below. 

TABLE 45—PROCEDURAL MITIGATION FOR AIR GUNS

Procedural mitigation description 

Stressor or Activity: 

• Air guns. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned on a ship or pierside. 

Mitigation Zone Size and Mitigation Requirements: 

• 150 yd around the air gun: 

• Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource 

is observed, do not commence use of air guns. 

• During the activity, observe for marine mammals; if resource is observed, cease use of air guns. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence the use of air guns until one of 

the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to 

have exited the mitigation zone based on a determination of its course, speed, and movement relative to the air gun; (3) the mitigation zone has been clear from any additional sightings for 30 min; or (4) for mobile activities, the air gun has transited a distance 

equal to double that of the mitigation zone size beyond the location of the last sighting. 

Procedural Mitigation for Pile Driving 

Procedural mitigation for pile driving 

is described in Table 46 below. 


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TABLE 46—PROCEDURAL MITIGATION FOR PILE DRIVING

Procedural mitigation description 

Stressor or Activity: 

• Pile driving and pile extraction sound during Elevated Causeway System Training. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned on the shore, the elevated causeway, or a small boat. 

Mitigation Zone Size and Mitigation Requirements: 

• 100 yd around the pile driver: 

• 30 min prior to the start of the activity, observe for floating vegetation and marine mammals; if resource is observed, do not commence impact pile driving or vibratory pile extraction. 

• During the activity, observe for marine mammals; if resource is observed, cease impact pile driving or vibratory pile extraction. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence pile driving until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the pile driving location; or (3) 

the mitigation zone has been clear from any additional sightings for 30 min. 

Procedural Mitigation for Weapons 

Firing Noise 

Procedural mitigation for weapons 

firing noise is described in Table 47 

below. 

TABLE 47—PROCEDURAL MITIGATION FOR WEAPONS FIRING NOISE

Procedural mitigation description 

Stressor or Activity: 

• Weapons firing noise associated with large-caliber gunnery activities. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned on the ship conducting the firing. 

• Depending on the activity, the Lookout could be the same as the one described in Table 50 (Procedural Mitigation for Explosive MediumCaliber and Large-Caliber Projectiles) or Table 60 (Procedural Mitigation for Small-, Medium-, and Large-Caliber Non-Explosive Practice 

Munitions) 

Mitigation Zone Size and Mitigation Requirements: 

• 30 degrees on either side of the firing line out to 70 yd from the muzzle of the weapon being fired: 

• Prior to the start of the activity, observe for floating vegetation and marine mammals; if resource is observed, do not commence 

weapons firing. 

• During the activity, observe for marine mammals; if resource is observed, cease weapons firing. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence weapons firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the firing ship; (3) the mitigation 

zone has been clear from any additional sightings for 30 min; or (4) for mobile activities, the firing ship has transited a distance equal 

to double that of the mitigation zone size beyond the location of the last sighting. 

Procedural Mitigation for Explosive 

Stressors 

Mitigation measures for explosive 

stressors are provided in Tables 48 

through 52. 

Procedural Mitigation for Explosive 

Sonobuoys 

Procedural mitigation for explosive 

sonobuoys is described in Table 48 

below. 

TABLE 48—PROCEDURAL MITIGATION FOR EXPLOSIVE SONOBUOYS

Procedural mitigation description 

Stressor or Activity: 

• Explosive sonobuoys. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned in an aircraft or on small boat. 

Mitigation Zone Size and Mitigation Requirements: 

• 600 yd around an explosive sonobuoy: 

• Prior to the start of the activity (e.g., during deployment of a sonobuoy field, which typically lasts 20–30 min), conduct passive acoustic monitoring for marine mammals, and observe for floating vegetation and marine mammals; if resource is visually observed, do not 

commence sonobuoy or source/receiver pair detonations. 

• During the activity, observe for marine mammals; if resource is observed, cease sonobuoy or source/receiver pair detonations. 


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TABLE 48—PROCEDURAL MITIGATION FOR EXPLOSIVE SONOBUOYS—Continued 

Procedural mitigation description 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence the use of explosive sonobuoys 

until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is 

thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the sonobuoy; or 

(3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft that have fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained. 

Procedural Mitigation for Explosive 

Torpedoes 

Procedural mitigation for explosive 

torpedoes is described in Table 49 

below. 

TABLE 49—PROCEDURAL MITIGATION FOR EXPLOSIVE TORPEDOES

Procedural mitigation description 

Stressor or Activity: 

• Explosive torpedoes. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned in an aircraft. 

Mitigation Zone Size and Mitigation Requirements: 

• 2,100 yd around the intended impact location: 

• Prior to the start of the activity (e.g., during deployment of the target), conduct passive acoustic monitoring for marine mammals, and 

observe for floating vegetation, jellyfish aggregations and marine mammals; if resource is visually observed, do not commence firing. 

• During the activity, observe for marine mammals and jellyfish aggregations; if resource is observed, cease firing. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; or 

(3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft that have fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained. 

• After completion of the activity, observe for marine mammals; if any injured or dead resources are observed, follow established incident reporting procedures. 

Procedural Mitigation for Medium- and 

Large-Caliber Projectiles 

Procedural mitigation for mediumand large-caliber projectiles is described 

in Table 50 below. 

TABLE 50—PROCEDURAL MITIGATION FOR EXPLOSIVE MEDIUM-CALIBER AND LARGE-CALIBER PROJECTILES

Procedural mitigation description 

Stressor or Activity: 

• Gunnery activities using explosive medium-caliber and large-caliber projectiles. 

• Mitigation applies to activities using a surface target. 

Number of Lookouts and Observation Platform: 

• 1 Lookout on the vessel or aircraft conducting the activity. 

Mitigation Zone Size and Mitigation Requirements: 

• 200 yd around the intended impact location for air-to-surface activities using explosive medium-caliber projectiles, or 

• 600 yd around the intended impact location for surface-to-surface activities using explosive medium-caliber projectiles, or 

• 1,000 yd around the intended impact location for surface-to-surface activities using explosive large-caliber projectiles: 

• Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource 

is observed, do not commence firing. 

• During the activity, observe for marine mammals; if resource is observed, cease firing. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; (3) 

the mitigation zone has been clear from any additional sightings for 10 min for aircraft-based firing or 30 min for vessel-based firing; 

or (4) for activities using mobile targets, the intended impact location has transited a distance equal to double that of the mitigation 

zone size beyond the location of the last sighting. 


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Procedural Mitigation for Explosive 

Missiles and Rockets 

Procedural mitigation for explosive 

missiles and rockets is described in 

Table 51 below. 

TABLE 51—PROCEDURAL MITIGATION FOR EXPLOSIVE MISSILES AND ROCKETS

Procedural mitigation description 

Stressor or Activity: 

• Aircraft-deployed explosive missiles and rockets. 

• Mitigation applies to activities using a surface target. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned in an aircraft. 

Mitigation Zone Size and Mitigation Requirements: 

• 900 yd around the intended impact location during activities for missiles or rockets with 0.6–20 lb net explosive weight, or 

• 2,000 yd around the intended impact location for missiles with 21–500 lb net explosive weight: 

• Prior to the start of the activity (e.g., during a fly-over of the mitigation zone), observe for floating vegetation and marine mammals; if 

resource is observed, do not commence firing. 

• During the activity, observe for marine mammals; if resource is observed, cease firing. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; or 

(3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft that have fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained. 

Procedural Mitigation for Explosive 

Bombs 

Procedural mitigation for explosive 

bombs is described in Table 52 below. 

TABLE 52—PROCEDURAL MITIGATION FOR EXPLOSIVE BOMBS

Procedural mitigation description 

Stressor or Activity: 

• Explosive bombs. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned in the aircraft conducting the activity. 

Mitigation Zone Size and Mitigation Requirements: 

• 2,500 yd around the intended target: 

• Prior to the start of the activity (e.g., when arriving on station), observe for floating vegetation and marine mammals; if resource is 

observed, do not commence bomb deployment. 

• During target approach, observe for marine mammals; if resource is observed, cease bomb deployment. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence bomb deployment until one of the 

recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have 

exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended target; (3) the mitigation zone has been clear from any additional sightings for 10 min; or (4) for activities using mobile targets, the intended target has 

transited a distance equal to double that of the mitigation zone size beyond the location of the last sighting. 

Procedural Mitigation for Sinking 

Exercises 

Procedural mitigation for sinking 

exercises is described in Table 53 

below. 

TABLE 53—PROCEDURAL MITIGATION FOR SINKING EXERCISES

Procedural mitigation description 

Stressor or Activity: 

• Sinking exercises. 

Number of Lookouts and Observation Platform: 

• 2 Lookouts (one positioned in an aircraft and one on a vessel). 

Mitigation Zone Size and Mitigation Requirements: 

• 2.5 nmi around the target ship hulk: 

• 90 min prior to the first firing, conduct aerial observations for floating vegetation, jellyfish aggregations and marine mammals; if resource is observed, do not commence firing. 


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TABLE 53—PROCEDURAL MITIGATION FOR SINKING EXERCISES—Continued 

Procedural mitigation description 

• During the activity, conduct passive acoustic monitoring and visually observe for marine mammals from the vessel; if resource is visually observed, cease firing. 

• Immediately after any planned or unplanned breaks in weapons firing of longer than 2 hours, observe for marine mammals from the

aircraft and vessel; if resource is observed, do not commence firing. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the target ship hulk; or (3) the 

mitigation zone has been clear from any additional sightings for 30 min. 

• For 2 hours after sinking the vessel (or until sunset, whichever comes first), observe for marine mammals; if any injured or dead resources are observed, follow established incident reporting procedures. 

Procedural Mitigation for Explosive 

Mine Countermeasure and 

Neutralization Activities 

Procedural mitigation for explosive 

mine countermeasure and neutralization 

activities is described in Table 54 

below. 

TABLE 54—PROCEDURAL MITIGATION FOR EXPLOSIVE MINE COUNTERMEASURE AND NEUTRALIZATION ACTIVITIES

Procedural mitigation description 

Stressor or Activity: 

• Explosive mine countermeasure and neutralization activities. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned on a vessel or in an aircraft when implementing the smaller mitigation zone. 

• 2 Lookouts (one positioned in an aircraft and one on a small boat) when implementing the larger mitigation zone. 

Mitigaton Zone Size and Mitigation Requirements: 

• 600 yd around the detonation site for activities using 0.1–5-lb net explosive weight, or 2,100 yd around the detonation site for 6–650 lb 

net explosive weight (including high explosive target mines): 

• Prior to the start of the activity (e.g., when maneuvering on station; typically, 10 min when the activity involves aircraft that have fuel 

constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained), observe for floating vegetation and 

marine mammals; if resource is observed, do not commence detonations. 

• During the activity, observe for marine mammals; if resource is observed, cease detonations. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence detonations until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to detonation site; or (3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft with fuel constraints, or 30 min 

when the activity involves aircraft that are not typically fuel constrained. 

• After completion of the activity, observe for marine mammals (typically 10 min when the activity involves aircraft that have fuel constraints or 30 min when the activity involves aircraft that are not typically fuel constrained); if any injured or dead resources are observed, follow established incident reporting procedures. 

Procedural Mitigation for Explosive 

Mine Neutralization Activities Involving 

Navy Divers 

Procedural mitigation for explosive 

mine neutralization activities involving 

Navy divers is described in Table 55 

below. 

TABLE 55—PROCEDURAL MITIGATION FOR EXPLOSIVE MINE NEUTRALIZATION ACTIVITIES INVOLVING NAVY DIVERS

Procedural mitigation description 

Stressor or Activity: 

• Explosive mine neutralization activities involving Navy divers. 

Number of Lookouts and Observation Platform: 

• 2 Lookouts (two small boats with one Lookout each, or one Lookout on a small boat and one in a rotary-wing aircraft) when implementing the smaller mitigation zone. 

• 4 Lookouts (two small boats with two Lookouts each), and a pilot or member of an aircrew will serve as an additional Lookout if aircraft 

are used during the activity, when implementing the larger mitigation zone. 

Mitigation Zone Size and Mitigation Requirements: 

• The Navy will not set time-delay firing devices (0.1–29 lb net explosive weight) to exceed 10 min. 

• 500 yd around the detonation site during activities under positive control using 0.1–20 lb net explosive weight, or 

• 1,000 yd around the detonation site during all activities using time-delay fuses (0.1–29 lb net explosive weight) and during activities 

under positive control using 21–60 lb net explosive weight: 


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TABLE 55—PROCEDURAL MITIGATION FOR EXPLOSIVE MINE NEUTRALIZATION ACTIVITIES INVOLVING NAVY DIVERS— 

Continued 

Procedural mitigation description 

• Prior to the start of the activity (e.g., when maneuvering on station for activities under positive control; 30 min for activities using 

time-delay firing devices), observe for floating vegetation and marine mammals; if resource is observed, do not commence detonations or fuse initiation. 

• During the activity, observe for marine mammals; if resource is observed, cease detonations or fuse initiation. 

• All divers placing the charges on mines will support the Lookouts while performing their regular duties and will report all sightings to 

their supporting small boat or Range Safety Officer. 

• To the maximum extent practicable depending on mission requirements, safety, and environmental conditions, boats will position 

themselves near the mid-point of the mitigation zone radius (but outside of the detonation plume and human safety zone), will position themselves on opposite sides of the detonation location (when two boats are used), and will travel in a circular pattern around 

the detonation location with one Lookout observing inward toward the detonation site and the other observing outward toward the

perimeter of the mitigation zone. 

• If used, aircraft will travel in a circular pattern around the detonation location to the maximum extent practicable. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence detonations or fuse initiation until 

one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is 

thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the detonation 

site; (3) the mitigation zone has been clear from any additional sightings for 10 min during activities under positive control with aircraft that have fuel constraints, or 30 min during activities under positive control with aircraft that are not typically fuel constrained 

and during activities using time-delay firing devices. 

• After completion of an activity using time-delay firing devices, observe for marine mammals for 30 min; if any injured or dead resources are observed, follow established incident reporting procedures. 

Procedural Mitigation for Underwater 

Demolition Multiple Charge—Mat 

Weave and Obstacle Loading 

Procedural mitigation for underwater 

demolition multiple charge—mat weave 

and obstacle Loading is described in 

Table 56 below. 

TABLE 56—PROCEDURAL MITIGATION FOR UNDERWATER DEMOLITION MULTIPLE CHARGE—MAT WEAVE AND OBSTACLE

LOADING

Procedural mitigation description 

Stressor or Activity: 

• Underwater Demolition Multiple Charge—Mat Weave and Obstacle Loading exercises. 

Number of Lookouts and Observation Platform: 

• 2 Lookouts (one on a small boat and one on shore from an elevated platform). 

Mitigation Zone Size and Mitigation Requirements: 

• 700 yd around the detonation site: 

• For 30 min prior to the first detonation, the Lookout positioned on a small boat will observe for floating vegetation and marine mammals; if resource is observed, do not commence the initial detonation. 

• For 10 min prior to the first detonation, the Lookout positioned on shore will use binoculars to observe for marine mammals; if resource is observed, do not commence the initial detonation until the mitigation zone has been clear of any additional sightings for a 

minimum of 10 min. 

• During the activity, observe for marine mammals; if resource is observed, cease detonations. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence detonations until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the detonation site; or (3) the 

mitigation zone has been clear from any additional sightings for 10 min (as determined by the shore observer). 

• After completion of the activity, the Lookout positioned on a small boat will observe for marine mammals for 30 min; if any injured or 

dead resources are observed, follow established incident reporting procedures. 

Procedural Mitigation for Maritime 

Security Operations—Anti-Swimmer 

Grenades 

Procedural mitigation for maritime 

security operations—anti-swimmer 

grenades is described in Table 57 below. 

TABLE 57—PROCEDURAL MITIGATION FOR MARITIME SECURITY OPERATIONS—ANTI-SWIMMER GRENADES

Procedural mitigation description 

Stressor or Activity: 

• Maritime Security Operations—Anti-Swimmer Grenades. 


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TABLE 57—PROCEDURAL MITIGATION FOR MARITIME SECURITY OPERATIONS—ANTI-SWIMMER GRENADES—Continued 

Procedural mitigation description 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned on the small boat conducting the activity. 

Mitigation Zone Size and Mitigation Requirements: 

• 200 yd around the intended detonation location: 

• Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource 

is observed, do not commence detonations. 

• During the activity, observe for marine mammals; if resource is observed, cease detonations. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence detonations until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended detonation location; 

(3) the mitigation zone has been clear from any additional sightings for 30 min; or (4) the intended detonation location has transited 

a distance equal to double that of the mitigation zone size beyond the location of the last sighting. 

Procedural Mitigation for Physical 

Disturbance and Strike Stressors 

Mitigation measures for physical 

disturbance and strike stressors are 

provided in Table 58 through Table 62. 

Procedural Mitigation for Vessel 

Movement 

Procedural mitigation for vessel 

movement is described in Table 58 

below. 

TABLE 58—PROCEDURAL MITIGATION FOR VESSEL MOVEMENT

Procedural mitigation description 

Stressor or Activity: 

• Vessel movement. 

• The mitigation will not be applied if (1) the vessel’s safety is threatened, (2) the vessel is restricted in its ability to maneuver (e.g., during 

launching and recovery of aircraft or landing craft, during towing activities, when mooring, etc.), (3) the vessel is operated autonomously, 

or (4) when impracticable based on mission requirements (e.g., during Amphibious Assault—Battalion Landing exercises). 

Number of Lookouts and Observation Platform: 

• 1 Lookout on the vessel that is underway. 

Mitigation Zone Size and Mitigation Requirements: 

• 500 yd around whales: 

• When underway, observe for marine mammals; if a whale is observed, maneuver to maintain distance. 

• 200 yd around all other marine mammals (except bow-riding dolphins and pinnipeds hauled out on man-made navigational structures, 

port structures, and vessels): 

• When underway, observe for marine mammals; if a marine mammal other than a whale, bow-riding dolphin, or hauled-out pinniped 

is observed, maneuver to maintain distance. 

Procedural Mitigation for Towed InWater Devices 

Procedural mitigation for towed inwater devices is described in Table 59 

below. 

TABLE 59—PROCEDURAL MITIGATION FOR TOWED IN-WATER DEVICES

Procedural mitigation description 

Stressor or Activity: 

• Towed in-water devices. 

• Mitigation applies to devices that are towed from a manned surface platform or manned aircraft. 

• The mitigation will not be applied if the safety of the towing platform or in-water device is threatened. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned on the manned towing platform. 

Mitigation Zone Size and Mitigation Requirements: 

• 250 yd around marine mammals: 

• During the activity, observe for marine mammals; if resource is observed, maneuver to maintain distance. 

Procedural Mitigation for Small-, 

Medium-, and Large-Caliber NonExplosive Practice Munitions 

Procedural mitigation for small-, 

medium-, and large-caliber nonexplosive practice munitions is 

described in Table 60 below. 


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TABLE 60—PROCEDURAL MITIGATION FOR SMALL-, MEDIUM-, AND LARGE-CALIBER NON-EXPLOSIVE PRACTICE MUNITIONS

Procedural mitigation description 

Stressor or Activity: 

• Gunnery activities using small-, medium-, and large-caliber non-explosive practice munitions. 

• Mitigation applies to activities using a surface target. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned on the platform conducting the activity. 

• Depending on the activity, the Lookout could be the same as the one described in Table 47 (Procedural Mitigation for Weapons Firing 

Noise). 

Mitigation Zone Size and Mitigation Requirements: 

• 200 yd around the intended impact location: 

• Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource 

is observed, do not commence firing. 

• During the activity, observe for marine mammals; if resource is observed, cease firing. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; (3) 

the mitigation zone has been clear from any additional sightings for 10 min for aircraft-based firing or 30 min for vessel-based firing; 

or (4) for activities using a mobile target, the intended impact location has transited a distance equal to double that of the mitigation 

zone size beyond the location of the last sighting. 

Procedural Mitigation for Non-Explosive 

Missiles and Rockets 

Procedural mitigation for nonexplosive missiles and rockets is 

described in Table 61 below. 

TABLE 61—PROCEDURAL MITIGATION FOR NON-EXPLOSIVE MISSILES AND ROCKETS

Procedural mitigation description 

Stressor or Activity: 

• Aircraft-deployed non-explosive missiles and rockets. 

• Mitigation applies to activities using a surface target. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned in an aircraft. 

Mitigation Zone Size and Mitigation Requirements: 

• 900 yd around the intended impact location: 

• Prior to the start of the activity (e.g., during a fly-over of the mitigation zone), observe for floating vegetation and marine mammals; if 

resource is observed, do not commence firing. 

• During the activity, observe for marine mammals; if resource is observed, cease firing. 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have

exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; or 

(3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft that have fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained. 

Procedural Mitigation for Non-Explosive 

Bombs and Mine Shapes 

Procedural mitigation for nonexplosive bombs and mine shapes is 

described in Table 62 below. 

TABLE 62—PROCEDURAL MITIGATION FOR NON-EXPLOSIVE BOMBS AND MINE SHAPES

Procedural mitigation description 

Stressor or Activity: 

• Non-explosive bombs. 

• Non-explosive mine shapes during mine laying activities. 

Number of Lookouts and Observation Platform: 

• 1 Lookout positioned in an aircraft. 

Mitigation Zone Size and Mitigation Requirements: 

• 1,000 yd around the intended target: 

• Prior to the start of the activity (e.g., when arriving on station), observe for floating vegetation and marine mammals; if resource is 

observed, do not commence bomb deployment or mine laying. 

• During approach of the target or intended minefield location, observe for marine mammals; if resource is observed, cease bomb deployment or mine laying. 


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TABLE 62—PROCEDURAL MITIGATION FOR NON-EXPLOSIVE BOMBS AND MINE SHAPES—Continued 

Procedural mitigation description 

• To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence bomb deployment or mine laying 

until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is 

thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended target or minefield location; (3) the mitigation zone has been clear from any additional sightings for 10 min; or (4) for activities using 

mobile targets, the intended target has transited a distance equal to double that of the mitigation zone size beyond the location of 

the last sighting. 

Mitigation Areas 

In addition to procedural mitigation, 

the Navy will implement mitigation 

measures within mitigation areas to 

avoid or minimize potential impacts on 

marine mammals (see the revised 

Figures provided in the Navy’s 

addendum to the application). A full 

technical analysis (for which the 

methods were summarized above) of the 

mitigation areas that the Navy 

considered for marine mammals is 

provided in Appendix K (Geographic 

Mitigation Assessment) of the HSTT 

DEIS/OEIS. The Navy has taken into 

account public comments received from 

the HSTT DEIS/OEIS, best available 

science, and the practicability of 

implementing additional mitigations 

and has enhanced their mitigation areas 

and mitigation measures to further 

reduce impacts to marine mammals, and 

therefore, the Navy revised their 

mitigation areas since their application. 

These revisions are discussed below and 

can be found as an addendum to the 

Navy’s application at https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/incidentaltake-authorizations-military-readinessactivities. The Navy will continue to 

work with NMFS to finalize its 

mitigation areas through the 

development of the rule. 

Information on the mitigation 

measures that the Navy will implement 

within mitigation areas is provided in 

Tables 63 and 64. The mitigation 

applies year-round unless specified 

otherwise in the tables. 

Mitigation Areas for the HRC 

Mitigation areas for the HRC are 

described in Table 63 below. The 

location of each mitigation area is in the 

Navy’s addendum to the application on 

Mitigation Areas. 

TABLE 63—MITIGATION AREAS FOR MARINE MAMMALS IN THE HAWAII RANGE COMPLEX

Mitigation area description 

Stressor or Activity: 

Sonar. 

Explosives.1

Vessel strikes. 

Resource Protection Focus: 

Marine mammals 

Mitigation Area Requirements: 

Hawaii Island Mitigation Area (year-round): 

• The Navy will minimize the use of mid-frequency active anti-submarine warfare sensor bins MF1 and MF4 to the maximum extent 

practicable. 

• The Navy will not conduct more than 300 hrs of MF1 and 20 hrs of MF4 per year. 

• Should national security present a requirement to conduct more than 300 hrs of MF1 or 20 hrs of MF4 per year, naval units will 

obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information (e.g., hours of sonar usage) in its annual activity reports. 

• The Navy will not use explosives 1 during training and testing. 

• Should national security present a requirement for the use of explosives in the area, naval units will obtain permission from the 

appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance 

notification and include the information (e.g., explosives usage) in its annual activity reports. 

4-Islands Region Mitigation Area (November 15–April 15): 

• The Navy will not use mid-frequency active anti-submarine warfare sensor MF1 from November 15–April 15. 

• Should national security present a requirement for the use of MF1 in the area from November 15–April 15, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information (e.g., hours of sonar usage) in its annual activity reports. 

Humpback Whale Special Reporting Areas (December 15–April 15): 

• The Navy will report the hours of MF1 used in the special reporting areas in its annual activity reports. 

Humpback Whale Awareness Notification Message Area (November 1–April 30): 

• The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including humpback whales. 

• To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to remain vigilant to the presence of large whale species (including humpback whales), that when concentrated seasonally, may become vulnerable to vessel strikes. 

• Lookouts will use the information from the awareness notification message to assist their visual observation of applicable mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. 

Notes: 

1Explosive restrictions for the Hawaii Island Mitigation Area apply only to those activities for which the Navy seeks MMPA authorization (e.g., 

surface-to-surface or air-to-surface missile and gunnery events, BOMBEX, and mine neutralization). 


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Mitigation Areas for the SOCAL Portion 

of the Study Area 

Mitigation areas for the SOCAL 

portion of the Study Area are described 

in Table 64 below. The location of each 

mitigation area is shown in the Navy’s 

addendum to the application on 

Mitigation Areas. 

TABLE 64—MITIGATION AREAS FOR MARINE MAMMALS IN THE SOUTHERN CALIFORNIA PORTION OF THE STUDY AREA

Mitigation area description 

Stressor or Activity: 

Sonar. 

Explosives. 

Vessel strikes. 

Resource Protection Focus: 

Marine mammals. 

Mitigation Area Requirements: 

San Diego Arc Mitigation Area (June 1–October 31): 

• The Navy will minimize the use of mid-frequency active anti-submarine warfare sensor bin MF1 to the maximum extent practicable.

• The Navy will not conduct more than 200 hrs of MF1 (with the exception of active sonar maintenance and systems checks) per 

year from June 1–October 31. 

• Should national security present a requirement to conduct more than 200 hrs of MF1 (with the exception of active sonar maintenance and systems checks) per year from June 1–October 31, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and 

include the information (e.g., hours of sonar usage) in its annual activity reports. 

• The Navy will not use explosives during large-caliber gunnery, torpedo, bombing, and missile (including 2.75 in rockets) activities 

during training and testing. 

• Should national security present a requirement to conduct large-caliber gunnery, torpedo, bombing, and missile (including 2.75 

in rockets) activities using explosives, naval units will obtain permission from the appropriate designated Command authority 

prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information (e.g., 

explosives usage) in its annual activity reports. 

Santa Barbara Island Mitigation Area (year-round): 

• The Navy will not use mid-frequency active anti-submarine warfare sensor MF1 and explosives in small-, medium-, and large-caliber 

gunnery; torpedo; bombing; and missile (including 2.75 in rockets) activities during unit-level training and major training exercises. 

• Should national security present a requirement for the use of mid-frequency active anti-submarine warfare sensor MF1 or explosives 

in small-, medium-, and large-caliber gunnery; torpedo; bombing; and missile (including 2.75 in rockets) activities during unit-level 

training or major training exercises for national security, naval units will obtain permission from the appropriate designated Command 

authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in 

its annual activity reports. 

Blue Whale (June 1–October 31), Gray Whale (November 1–March 31), and Fin Whale (November 1–May 31) Awareness Notification Message Areas: 

• The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including blue, gray, or fin whales. 

• To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to remain vigilant to the presence of large whale species, that when concentrated seasonally, may become vulnerable to vessel 

strikes. 

• Lookouts will use the information from the awareness notification messages to assist their visual observation of applicable mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. 

NMFS conducted an independent 

analysis of the mitigation areas that the 

Navy proposed, which are described 

below. NMFS concurs with the Navy’s 

analysis, which indicates that the 

measures in these mitigation areas are 

both practicable (which is the Navy’s 

purview to determine) and will reduce 

the likelihood or severity of adverse 

impacts to marine mammal species or 

stocks or their habitat in the manner 

described in the Navy’s analysis. 

Specifically, the mitigation areas will 

provide the following benefits to the 

affected stocks: 

4-Islands Region Mitigation Area 

(Seasonal Nov 15–Apr 15): The Maui/ 

Molokai area (4-Islands Region) is an 

important reproductive and calving area 

for humpback whales. Recent scientific 

research indicates peak humpback 

whale season has expanded, with higher 

densities of whales occurring earlier 

than prior studies had indicated. In 

addition, a portion of this area has also 

been identified as biologically important 

for the ESA-listed small and resident 

population, main Hawaiian Island 

insular false killer whales. While the 

season for this area used to be from 

December 15 to April 15, the Navy has 

proposed to extend it from November 15 

to April 15. Extending the season and 

size of the 4-Islands Region Mitigation 

Area will provide some added 

protection for that species during half of 

the year. Minimizing impacts in this 

area and time is expected to reduce the 

likelihood of more serious impacts from 

sonar that could interfere with 

important cow/calf communication or 

have unforeseen impacts on more 

sensitive calves. This area also overlaps 

with identified biologically important 

areas for other marine mammal species 

such as dolphin species including 

Common bottlenose dolphin, 

pantropical spotted dolphin, and 

spinner dolphin (small and resident 

populations). 

Hawaii Island Mitigation Area (Yearround): The endangered main Hawaiian 

Island insular false killer whale, which 

is a small and resident populations, and 

two species of beaked whales (Cuvier 

and Blainville’s) have been documented 

using this area year-round to support 

multiple biological functions. Main 

Hawaiian Island insular false killer 

whales are an endangered species and 

beaked whales are scientifically shown 

to be highly sensitive to exposure to 

sonar. This area also overlaps with other 

identified biologically important areas 

for other marine mammal species such 

as humpback whale (important 

reproductive/calving area), dwarf sperm 

whale (small and resident populations), 

pygmy killer whale (small and resident 


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population), melon-headed whale (small 

and resident population), short-finned 

pilot whale (small and resident 

population) and dolphin species 

including Common bottlenose dolphin, 

pantropical spotted dolphin, spinner 

dolphin, and rough-toothed dolphin 

(small and resident populations) for 

which the Hawaii Island Mitigation 

Area would provide additional 

protection. 

Potential benefits to humpback 

whales are noted in the section above. 

For beaked whales, which have been 

shown to be more sensitive to loud 

sounds, a reduction of impacts in 

general where the stock is known to live 

or concentrate is expected to reduce the 

likelihood that more severe responses 

that could affect individual fitness 

would occur. For small resident 

populations, one goal is to ensure that 

the entirety of any small population is 

not being extensively impacted, in order 

to reduce the probability that repeated 

behavioral exposures to small numbers 

of individuals will result in energetic 

impacts, or other impacts with the 

potential to reduce survival or 

reproductive success on individuals that 

will more readily accrue to population 

level impacts in smaller stocks. 

Santa Barbara Island Mitigation Area 

(Year-round): Numerous marine 

mammal species use the Channel 

Islands NMS and it provides valuable, 

and protected, marine mammal habitat. 

Particularly, this mitigation area will 

overlap with identified biologically 

important feeding area for blue whales 

and migration areas for gray whales. 

Generally, a reduction of impacts in the 

Santa Barbara Island Mitigation Area 

(inclusive of a portion of the Channel 

Islands NMS) is expected to reduce 

stressors in an area that likely contains 

high value habitat that is more typically 

free of other anthropogenic stressors. 

San Diego Arc Mitigation Area 

(Seasonal Jun 1–Oct 31): Endangered 

blue whales have been documented 

foraging in this area seasonally. 

Reducing harassing exposures of marine 

mammals to sonar and explosives in 

feeding areas, even when the animals 

have demonstrated some tolerance for 

disturbance when in a feeding state, is 

expected to reduce the likelihood that 

feeding would be interrupted to a degree 

that energetic reserves might be affected 

in a manner that could reduce 

survivorship or reproductive success. 

This mitigation area will also partially 

overlap with an important migration 

area for gray whales. 

Summary of Mitigation 

The Navy’s proposed mitigation 

measures are summarized in Tables 65 

and 66. 

Summary of Procedural Mitigation 

A summary of procedural mitigation 

is described in Table 65 below. 

TABLE 65—SUMMARY OF PROCEDURAL MITIGATION

Stressor or activity Summary of mitigation requirements 

Environmental Awareness and Education ............................... Afloat Environmental Compliance Training program for applicable personnel. 

Active Sonar (depending on system) ....................................... Depending on sonar source: 1,000 yd power down, 500 yd power down, and 200 

yd shut down or 200 yd shut down. 

Air Guns ................................................................................... 150 yd. 

Pile Driving ............................................................................... 100 yd. 

Weapons Firing Noise .............................................................. 30 degrees on either side of the firing line out to 70 yd. 

Explosive Sonobuoys ............................................................... 600 yd. 

Explosive Torpedoes ................................................................ 2,100 yd. 

Explosive Medium-Caliber and Large-Caliber Projectiles ........ 1,000 yd (large-caliber projectiles); 600 yd (medium-caliber projectiles during surface-to-surface activities) or 200 yd (medium-caliber projectiles during air-tosurface activities). 

Explosive Missiles and Rockets ............................................... 900 yd (0.6–20 lb net explosive weight) or 2,000 yd (21–500 lb net explosive 

weight). 

Explosive Bombs ...................................................................... 2,500 yd. 

Sinking Exercises ..................................................................... 2.5 nmi. 

Explosive Mine Countermeasure and Neutralization Activities 600 yd (0.1–5 lb net explosive weight) or 2,100 yd (6–650 lb net explosive 

weight). 

Explosive Mine Neutralization Activities Involving Navy Divers 500 yd (0.1–20 lb net explosive weight for positive control charges), or 1,000 yd 

(21–60 lb net explosive weight for positive control charges and all charges 

using time-delay fuses). 

Underwater Demolition Multiple Charge—Mat Weave and 

Obstacle Loading.

700 yd. 

Maritime Security Operations—Anti-Swimmer Grenades ........ 200 yd. 

Vessel Movement ..................................................................... 500 yd (whales) or 200 yd (other marine mammals). 

Towed In-Water Devices .......................................................... 250 yd. 

Small-, Medium-, and Large-Caliber Non-Explosive Practice 

Munitions.

200 yd. 

Non-Explosive Missiles and Rockets ....................................... 900 yd. 

Non-Explosive Bombs and Mine Shapes ................................ 1,000 yd. 

Summary of Mitigation Areas 

A summary of mitigation areas for 

marine mammals is described in Table 

66 below. 


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TABLE 66—SUMMARY OF MITIGATION AREAS FOR MARINE MAMMALS

Mitigation area Summary of mitigation requirements 

Mitigation Areas for Marine Mammals 

Hawaii Island Mitigation Area 

(Year-round).

• The Navy would not exceed 300 hrs of mid-frequency active anti-submarine warfare sensor MF1 and 20 

hrs of mid-frequency active anti-submarine warfare sensor MF4 per season annually. 

• Should national security present a requirement to conduct additional training and testing using MF1 

or MF4 in the mitigation area for national security, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide 

NMFS with advance notification and include the information in associated reports. 

• The Navy will not use explosives 1 during training or testing activities. 

• Should national security present a requirement to use explosives, naval units will obtain permission 

from the appropriate designated Command authority prior to commencement of the activity. The 

Navy will provide NMFS with advance notification and include the information in associated annual 

reports. 

4-Islands Region Mitigation Area 

(November 15–April 15).

• The Navy will not use mid-frequency active anti-submarine warfare sensor MF1 during training or testing 

activities. 

• Should national security present a requirement to use MF1 during training or testing, naval units will 

obtain permission from the appropriate designated Command authority prior to commencement of 

the activity. The Navy will provide NMFS with advance notification and include the information in associated annual reports. 

San Diego Arc Mitigation Area 

(June 1–October 31).

• The Navy would not exceed 200 hrs of mid-frequency active anti-submarine warfare sensor MF1 (with 

the exception of active sonar maintenance and systems checks) annually within the area. 

• Should national security present a requirement to conduct additional training and testing using MF1, 

naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in associated annual reports. 

• The Navy will not use explosives during large-caliber gunnery, torpedo, bombing, and missile (including 

2.75 in rockets) activities during training or testing activities. 

• Should national security present a requirement to use these explosives during training or testing activities, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in associated annual reports. 

Santa Barbara Island Mitigation 

Area (Year-round).

• The Navy will not use mid-frequency active anti-submarine warfare sensor MF1 and explosives in small-, 

medium-, and large-caliber gunnery; torpedo; bombing; and missile (including 2.75 in rockets) activities 

during unit-level training or major training exercises. 

• Should national security present a requirement to use MF1 or these explosives during training or testing 

activities, naval units will obtain permission from the appropriate designated Command authority prior to 

commencement of the activity. The Navy will provide NMFS with advance notification and include the information in associated annual reports. 

Notes: 

1Explosive restrictions within the Hawaii Island Mitigation Area apply only to those activities for which the Navy seeks MMPA authorization 

(e.g., surface-to-surface or air-to-surface missile and gunnery events, BOMBEX, and mine neutralization). 

Mitigation Conclusions 

NMFS has carefully evaluated the 

Navy’s proposed mitigation measures— 

many of which were developed with 

NMFS’s input during the previous 

phases of Navy training and testing 

authorizations—and considered a broad 

range of other measures (i.e., the 

measures considered but eliminated in 

the Navy’s DEIS/OEIS, which reflect 

many of the comments that have arisen 

via NMFS or public input in past years) 

in the context of ensuring that NMFS 

prescribes the means of effecting the 

least practicable adverse impact on the 

affected marine mammal species and 

stocks and their habitat. Our evaluation 

of potential measures included 

consideration of the following factors in 

relation to one another: The manner in 

which, and the degree to which, the 

successful implementation of the 

mitigation measures is expected to 

reduce the likelihood and/or magnitude 

of adverse impacts to marine mammal 

species and stocks and their habitat; the 

proven or likely efficacy of the 

measures; and the practicability of the 

measures for applicant implementation, 

including consideration of personnel 

safety, practicality of implementation, 

and impact on the effectiveness of the 

military readiness activity. 

Based on our evaluation of the Navy’s 

proposed measures, as well as other 

measures considered by the Navy and 

NMFS, NMFS has preliminarily 

determined that the Navy’s proposed 

mitigation measures are adequate means 

of effecting the least practicable adverse 

impacts on marine mammals species or 

stocks and their habitat, paying 

particular attention to rookeries, mating 

grounds, and areas of similar 

significance, while also considering 

personnel safety, practicality of 

implementation, and impact on the 

effectiveness of the military readiness 

activity. Additionally, the adaptive 

management component helps further 

ensure that mitigation is regularly 

assessed and opportunities are available 

to improve the mitigation, based on the 

factors above, through modification as 

appropriate. The proposed rule 

comment period provides the public an 

opportunity to submit 

recommendations, views, and/or 

concerns regarding the proposed 

mitigation measures. While NMFS has 

preliminarily determined that the 

Navy’s proposed mitigation measures 

would effect the least practicable 

adverse impact on the affected species 

or stocks and their habitat, NMFS will 

consider all public comments to help 

inform our final decision. Consequently, 

the proposed mitigation measures may 

be refined, modified, removed, or added 

to prior to the issuance of any final rule 

based on public comments received, 

and where appropriate, further analysis 

of any additional mitigation measures. 


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Proposed Monitoring 

Section 101(a)(5)(A) of the MMPA 

states that in order to issue an ITA for 

an activity, 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 LOAs 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. 

Although the Navy has been 

conducting research and monitoring in 

the HSTT Study Area for over 20 years, 

they developed a formal marine species 

monitoring program in support of the 

MMPA and ESA authorizations for the 

Hawaii and Southern California range 

complexes in 2009. This robust program 

has resulted in hundreds of technical 

reports and publications on marine 

mammals that have informed Navy and 

NMFS analysis in environmental 

planning documents, Rules and 

Biological Opinions. The reports are 

made available to the public on the 

Navy’s marine species monitoring 

website (www.navymarinespecies

monitoring.us) and the data on the 

Ocean Biogeographic Information 

System Spatial Ecological Analysis of 

Megavertebrate Populations (OBIS– 

SEAMAP) (www.seamap.env.duke.edu). 

The Navy would continue collecting 

monitoring data to inform our 

understanding of: The occurrence of 

marine mammals in the action area; the 

likely exposure of marine mammals to 

stressors of concern in the area; the 

response of marine mammals to 

exposures to stressors; the consequences 

of a particular marine mammal response 

to their individual fitness and, 

ultimately, populations; and, the 

effectiveness of implemented mitigation 

measures. Taken together, mitigation 

and monitoring comprise the Navy’s 

integrated approach for reducing 

environmental impacts from the 

specified activities. The Navy’s overall 

monitoring approach will seek to 

leverage and build on existing research 

efforts whenever possible. 

Consistent with the cooperating 

agency agreement between the Navy and 

NMFS, monitoring measures presented 

here, as well as the mitigation measures 

described above, focus on the protection 

and management of potentially affected 

marine mammals. A well-designed 

monitoring program can provide 

important feedback for validating 

assumptions made in analyses and 

allow for adaptive management of 

marine resources. Monitoring is 

required under the MMPA, and details 

of the monitoring program for the 

specified activities have been developed 

through coordination between NMFS 

and the Navy through the regulatory 

process for previous Navy at-sea 

training and testing actions. Input 

received during the public comment 

period and discussions with other 

agencies or NMFS offices during the 

rulemaking process could result in 

changes to the monitoring as described 

in this document. 

Integrated Comprehensive Monitoring 

Program (ICMP) 

The Navy’s ICMP is intended to 

coordinate marine species monitoring 

efforts across all regions and to allocate 

the most appropriate level and type of 

effort for each range complex based on 

a set of standardized objectives, and in 

acknowledgement of regional expertise 

and resource availability. The ICMP is 

designed to be flexible, scalable, and 

adaptable through the adaptive 

management and strategic planning 

processes to periodically assess progress 

and reevaluate objectives. This process 

includes conducting an annual adaptive 

management review meeting, at which 

the Navy and NMFS jointly consider the 

prior-year goals, monitoring results, and 

related scientific advances to determine 

if monitoring plan modifications are 

warranted to more effectively address 

program goals. Although the ICMP does 

not specify actual monitoring field work 

or individual projects, it does establish 

a matrix of goals and objectives that 

have been developed in coordination 

with NMFS. As the ICMP is 

implemented through the Strategic 

Planning Process, detailed and specific 

studies will be developed which 

support the Navy’s and NMFS top-level 

monitoring goals. In essence, the ICMP 

directs that monitoring activities 

relating to the effects of Navy training 

and testing activities on marine species 

should be designed to contribute 

towards one or more of the following 

top-level goals: 

• An increase in understanding of the 

likely occurrence of marine mammals 

and/or ESA-listed marine species in the 

vicinity of the action (i.e., presence, 

abundance, distribution, and/or density 

of species); 

• An increase in understanding of the 

nature, scope, or context of the likely 

exposure of marine mammals and/or 

ESA-listed species to any of the 

potential stressor(s) associated with the 

action (e.g., sound, explosive 

detonation, or military expended 

materials), through better understanding 

of one or more of the following: (1) The 

action and the environment in which it 

occurs (e.g., sound source 

characterization, propagation, and 

ambient noise levels); (2) the affected 

species (e.g., life history or dive 

patterns); (3) the likely co-occurrence of 

marine mammals and/or ESA-listed 

marine species with the action (in 

whole or part), and/or; (4) the likely 

biological or behavioral context of 

exposure to the stressor for the marine 

mammal and/or ESA-listed marine 

species (e.g., age class of exposed 

animals or known pupping, calving or 

feeding areas); 

• An increase in understanding of 

how individual marine mammals or 

ESA-listed marine species respond 

(behaviorally or physiologically) to the 

specific stressors associated with the 

action (in specific contexts, where 

possible, e.g., at what distance or 

received level); 

• An increase in understanding of 

how anticipated individual responses, 

to individual stressors or anticipated 

combinations of stressors, may impact 

either: (1) The long-term fitness and 

survival of an individual; or (2) the 

population, species, or stock (e.g., 

through effects on annual rates of 

recruitment or survival); 

• An increase in understanding of the 

effectiveness of mitigation and 

monitoring measures; 

• A better understanding and record 

of the manner in which the authorized 

entity complies with the ITA and 

Incidental Take Statement; 

• An increase in the probability of 

detecting marine mammals (through 

improved technology or methods), both 

specifically within the mitigation zone 

(thus allowing for more effective 

implementation of the mitigation) and 

in general, to better achieve the above 

goals; and 

• A reduction in the adverse impact 

of activities to the least practicable 

level, as defined in the MMPA. 

Strategic Planning Process for Marine 

Species Monitoring 

The Navy also developed the Strategic 

Planning Process for Marine Species 

Monitoring, which establishes the 

guidelines and processes necessary to 

develop, evaluate, and fund individual 

projects based on objective scientific 

study questions. The process uses an 

underlying framework designed around 

the ICMP’s top-level goals, and a 

conceptual framework incorporating a 

progression of knowledge, spanning 

occurrence, exposure, response, and 

consequences. The Strategic Planning 

Process for Marine Species Monitoring 

is used to set overarching intermediate 


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scientific objectives, develop individual 

monitoring project concepts, identify 

potential species of interest at a regional 

scale, evaluate, prioritize and select 

specific monitoring projects to fund or 

continue supporting for a given fiscal 

year, execute and manage selected 

monitoring projects, and report and 

evaluate progress and results. This 

process addresses relative investments 

to different range complexes based on 

goals across all range complexes, and 

monitoring leverages multiple 

techniques for data acquisition and 

analysis whenever possible. The 

Strategic Planning Process for Marine 

Species Monitoring is also available 

online (http://www.navymarinespecies

monitoring.us/). 

Monitoring Progress in the Study Area 

The monitoring program has 

undergone significant changes that 

highlight its evolution through the 

process of adaptive management. The 

monitoring program developed for the 

first cycle of environmental compliance 

documents (e.g., (U.S. Department of the 

Navy, 2008)) utilized effort-based 

compliance metrics that were somewhat 

limiting. Through adaptive management 

discussions, the Navy designed and 

conducted monitoring studies according 

to scientific objectives, thereby 

eliminating basing requirements upon 

metrics of level-of-effort. Furthermore, 

refinements of scientific objective have 

continued through the latest permit 

cycle through 2018. 

Progress has also been made on the 

monitoring program’s conceptual 

framework categories from the Scientific 

Advisory Group for Navy Marine 

Species Monitoring (U.S. Department of 

the Navy, 2011e), ranging from 

occurrence of animals, to their 

exposure, response, and population 

consequences. Lessons-learned with 

Phase I and II monitoring in HRC and 

SOCAL suggested that ‘‘layering’’ 

multiple components of monitoring 

simultaneously provides a way to 

leverage an increase in return of the 

progress toward answering scientific 

monitoring questions. 

Specific Phase II monitoring has 

included: 

• HRC 

Æ Long-term Trends in Abundance of 

Marine Mammals at PMRF; 

Æ Estimation of Received Levels of 

Mid-Frequency Active Sonar on Marine 

Mammals at PMRF; 

Æ Behavioral Response of Marine 

Mammals to Navy Training and Testing 

at PMRF; and 

Æ Navy Civilian Marine Mammal 

Observers on MFAS Ships in Offshore 

Waters of HRC. 

• SOCAL 

Æ Blue and Fin Whale Satellite 

Tagging; 

Æ Cuvier’s Beaked Whale Impact 

Assessment at the Southern California 

Offshore Antisubmarine Warfare Range 

(SOAR); 

Æ Cuvier’s Beaked Whale, Blue 

Whale, and Fin Whale Impact 

Assessments at Non-Instrumented 

Range Locations in SOCAL; and 

Æ Marine Mammal Sightings during 

California Cooperative Oceanic 

Fisheries Investigation (CalCOFI) 

Cruises. 

Numerous publications, dissertations 

and conference presentations have 

resulted from research conducted under 

the Navy’s marine species monitoring 

program (https://www.navymarine

speciesmonitoring.us/reading-room/ 

publications/), resulting in a significant 

contribution to the body of marine 

mammal science. Publications on 

occurrence, distribution and density 

have fed the modeling input, and 

publications on exposure and response 

have informed Navy and NMFS 

analyses of behavioral response and 

consideration of mitigation measures. 

Furthermore, collaboration between 

the monitoring program and the Navy’s 

research and development (e.g., the 

Office of Naval Research) and 

demonstration-validation (e.g., Living 

Marine Resources) programs has been 

strengthened, leading to research tools 

and products that have already 

transitioned to the monitoring program. 

These include Marine Mammal 

Monitoring on Ranges (M3R), controlled 

exposure experiment behavioral 

response studies (CEE BRS), acoustic 

sea glider surveys, and global 

positioning system-enabled satellite 

tags. Recent progress has been made 

with better integration of monitoring 

across all Navy at-sea study areas, 

including study areas in the Pacific and 

the Atlantic Oceans, and various testing 

ranges. Publications from the Living 

Marine Resources and Office of Naval 

Research programs have also resulted in 

significant contributions to hearing, 

acoustic criteria used in effects 

modeling, exposure, and response, as 

well as developing tools to assess 

biological significance (e.g., populationlevel consequences). 

NMFS and Navy also consider data 

collected during procedural mitigations 

as monitoring. Data are collected by 

shipboard personnel on hours spent 

training, hours of observation, hours of 

sonar, marine mammals observed 

within the mitigation zone during Major 

Training Exercises when mitigations are 

implemented. These data are provided 

to NMFS in both classified and 

unclassified annual exercise reports. 

Past and Current Monitoring in the 

Study Area 

NMFS has received multiple years’ 

worth of annual exercise and 

monitoring reports addressing active 

sonar use and explosive detonations 

within the HSTT Study Area and other 

Navy range complexes. The data and 

information contained in these reports 

have been considered in developing 

mitigation and monitoring measures for 

the proposed training and testing 

activities within the HSTT Study Area. 

The Navy’s annual exercise and 

monitoring reports may be viewed at: 

http://www.nmfs.noaa.gov/pr/permits/ 

incidental/military.htm and http://

www.navymarinespeciesmonitoring.us. 

The Navy has been funding various 

marine mammal studies and research 

within the HSTT Study Area for the past 

20 years. Under permitting from NMFS 

starting in 2009, this effort has 

transitioned from a specific metric 

based approach, to a broader new 

research only approach (e.g., set number 

of visual surveys, specific number of 

passive acoustic recording devices, etc.), 

and more recently since 2014 a more 

regional (Hawaii or Southern California) 

species-specific study question design 

(e.g., what is distribution of species A 

within the HSTT Study Area, what is 

response of species B to Navy activities, 

etc.). 

In adaptive management consultation 

with NMFS, some variation of these 

ongoing studies or proposed new 

studies will continue within the HSTT 

Study Area for either the duration of 

any new regulations, or for a set period 

as specified in a given project’s scope. 

Some projects may only require one or 

two years of field effort. Other projects 

could entail multi-year field efforts (two 

to five years). For instance, in the 

SOCAL portion of the HSTT Study 

Area, the Navy has funded development 

and application of new passive acoustic 

technology since the early 2000’s for 

detecting Cuvier’s beaked whales. This 

also includes ongoing effort to further 

identify and update population 

demographics for Cuvier’s beaked 

whales (re-sighting rates, population 

growth, calving rates, movements, etc.) 

specific to Navy training and testing 

areas, as well as responses to Navy 

activity. Variations of these Cuvier’s 

beaked whale monitoring studies will 

likely continue under future 

authorizations. The Navy’s marine 

species monitoring web portal provides 

details on past and current monitoring 

projects, including technical reports, 

publications, presentations, and access 


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to available data and can be found at: 

https://www.navymarinespecies

monitoring.us/regions/pacific/currentprojects/. 

The Navy’s marine species monitoring 

program typically supports 6–10 

monitoring projects in the HSTT Study 

Area at any given time. Projects can be 

either major multi-year major efforts, or 

one to two year special studies. Navy 

monitoring projects in HSTT through 

2018 currently include: 

• Long-term Trends In Abundance Of 

Marine Mammals At The Pacific Missile 

Range Facility (Hawaii—began in 2015); 

• Estimation Of Received Levels Of 

Mid-frequency Active Sonar On Marine 

Mammals At The Pacific Missile Range 

Facility (Hawaii—began in 2009); 

• Behavioral Response Of Marine 

Mammals To Training And Testing At 

The Pacific Missile Range Facility 

(Hawaii—began in 2009); 

• Humpback Whale Satellite Tracking 

And Genetics (Hawaii, Southern 

California—began in 2017); 

• Navy Civilian Marine Mammal 

Observers On Navy Destroyers (Hawaii, 

Southern California began in 2010); 

• Blue and Fin Whale Satellite 

Tracking And Genetics (Southern 

California—field work 2014–2017 with 

ongoing analysis); 

• Cuvier’s Beaked Whale Population 

Assessment And Impact Assessment At 

Southern California Anti-Submarine 

Range (Southern California—began in 

2015); 

• Cuvier’s Beaked Whale Occurrence 

In Southern California From Passive 

Acoustic Monitoring (Southern 

California—began in 2012); and 

• Guadalupe Fur Seal Satellite 

Tracking and Census (Southern 

California—one-year effort beginning in 

2018). 

Additional scientific projects may 

have field efforts within Hawaii and 

Southern California under separate 

Navy funding from the Navy’s two 

marine species research programs, the 

Office of Naval Research Marine 

Mammals and Biology Program and the 

Living Marine Resources Program. The 

periodicity of these research projects are 

more variable than the Navy’s 

compliance monitoring described above. 

Adaptive Management 

The final regulations governing the 

take of marine mammals incidental to 

Navy training and testing activities in 

the Study Area would contain an 

adaptive management component. Our 

understanding of the effects of Navy 

training and testing activities (e.g., 

acoustic and explosive stressors) on 

marine mammals continues to evolve, 

which makes the inclusion of an 

adaptive management component both 

valuable and necessary within the 

context of five-year regulations. 

The reporting requirements associated 

with this proposed rule are designed to 

provide NMFS with monitoring data 

from the previous year to allow NMFS 

to consider whether any changes to 

existing mitigation and monitoring 

requirements are appropriate. NMFS 

and the Navy would meet to discuss the 

monitoring reports, Navy R&D 

developments, and current science and 

whether mitigation or monitoring 

modifications are appropriate. The use 

of adaptive management allows NMFS 

to consider new information from 

different sources to determine (with 

input from the Navy regarding 

practicability) on an annual or biennial 

basis if mitigation or monitoring 

measures should be modified (including 

additions or deletions). Mitigation 

measures could be modified if new data 

suggests that such modifications would 

have a reasonable likelihood of reducing 

adverse effects to marine mammals and 

if the measures are practicable. 

The following are some of the 

possible sources of applicable data to be 

considered through the adaptive 

management process: (1) Results from 

monitoring and exercises reports, as 

required by MMPA authorizations; (2) 

compiled results of Navy funded R&D 

studies; (3) results from specific 

stranding investigations; (4) results from 

general marine mammal and sound 

research; and (5) any information which 

reveals that marine mammals may have 

been taken in a manner, extent, or 

number not authorized by these 

regulations or subsequent LOAs. 

Proposed Reporting 

In order to issue an incidental take 

authorization for an activity, section 

101(a)(5)(A) of the MMPA states that 

NMFS must set forth ‘‘requirements 

pertaining to the monitoring and 

reporting of such taking.’’ Effective 

reporting is critical both to compliance 

as well as ensuring that the most value 

is obtained from the required 

monitoring. Some of the reporting 

requirements are still in development 

and the final rulemaking may contain 

additional minor details not contained 

here. Additionally, proposed reporting 

requirements may be modified, 

removed, or added based on information 

or comments received during the public 

comment period. Reports from 

individual monitoring events, results of 

analyses, publications, and periodic 

progress reports for specific 

monitoring projects would be posted to 

the Navy’s Marine Species Monitoring 

web portal: http://www.navymarine

speciesmonitoring.us. Currently, there 

are several different reporting 

requirements pursuant to these 

proposed regulations: 

Notification of Injured, Live Stranded or 

Dead Marine Mammals 

The Navy will abide by the 

Notification and Reporting Plan, which 

sets out notification, reporting, and 

other requirements when injured, live 

stranded, or dead marine mammals are 

detected. The Notification and 

Reporting Plan will be available for 

review at https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/incidentaltake-authorizations-military-readinessactivities. 

Annual HSTT Monitoring Report 

The Navy shall submit an annual 

report to NMFS of the HSTT monitoring 

describing the implementation and 

results from the previous calendar year. 

Data collection methods will be 

standardized across range complexes 

and HSTT Study Area to allow for 

comparison in different geographic 

locations. The draft of the annual 

monitoring report shall be submitted 

either three months after the calendar 

year, or three months after the 

conclusion of the monitoring year to be 

determined by the Adaptive 

Management process. Such a report 

would describe progress of knowledge 

made with respect to intermediate 

scientific objectives within the HSTT 

Study Area associated with the 

Integrated Comprehensive Monitoring 

Program. Similar study questions shall 

be treated together so that summaries 

can be provided for each topic area. The 

report need not include analyses and 

content that does not provide direct 

assessment of cumulative progress on 

the monitoring plan study questions. 

NMFS will submit comments on the 

draft monitoring report, if any, within 

three months of receipt. The report will 

be considered final after the Navy has 

addressed NMFS’s comments, or three 

months after the submittal of the draft 

if NMFS does not have comments. 

As an alternative, the Navy may 

submit a multi-Range Complex annual 

Monitoring Plan report to fulfill this 

requirement. Such a report would 

describe progress of knowledge made 

with respect to monitoring study 

questions across multiple Navy ranges 

associated with the ICMP. Similar study 

questions shall be treated together so 

that progress on each topic shall be 

summarized across multiple Navy 

ranges. The report need not include 

analyses and content that does not 

provide direct assessment of cumulative 


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progress on the monitoring study 

question. This will continue to allow 

Navy to provide a cohesive monitoring 

report covering multiple ranges (as per 

ICMP goals), rather than entirely 

separate reports for the HSTT, Gulf of 

Alaska, Mariana Islands, and the 

Northwest Study Areas, etc. 

Annual HSTT Training Exercise Report 

and Testing Activity Report 

Each year, the Navy will submit two 

preliminary reports to NMFS detailing 

the status of authorized sound sources 

within 21 days after the anniversary of 

the date of issuance of the LOA. Each 

year, the Navy shall submit detailed 

reports to NMFS within 3 months after 

the anniversary of the date of issuance 

of the LOA. The annual reports shall 

contain information on MTEs, Sinking 

Exercise (SINKEX) events, and a 

summary of all sound sources used 

(total hours or quantity (per the LOA) of 

each bin of sonar or other nonimpulsive source; total annual number 

of each type of explosive exercises; and 

total annual expended/detonated 

rounds (missiles, bombs, sonobuoys, 

etc.) for each explosive bin). The 

analysis in the detailed reports will be 

based on the accumulation of data from 

the current year’s report and data 

collected from previous reports. The 

Annual HSTT Training Exercise Report 

and Testing Activity Navy reports can 

be consolidated with other exercise 

reports from other range complexes in 

the Pacific Ocean for a single Pacific 

Exercise Report, if desired. Specific subreporting in these annual reports 

include: 

• Humpback Whale Special Reporting 

Area (December 15–April 15): The Navy 

will report the total hours of operation 

of surface ship hull-mounted midfrequency active sonar used in the 

special reporting area; 

• HSTT Mitigation Areas (see section 

11 of the Navy’s application): The Navy 

will report any use that occurred as 

specifically described in these areas; 

and 

• Information included in the 

classified annual reports may be used to 

inform future adaptive management of 

activities within the HSTT Study Area. 

Other Reporting and Coordination 

The Navy will continue to report and 

coordinate with NMFS for the 

following: 

• Annual marine species monitoring 

technical review meetings with 

researchers, regulators and Marine 

Mammal Commission (currently, every 

two years a joint Pacific-Atlantic 

meeting is held); and 

• Annual Adaptive Management 

meetings with NMFS, regulators and 

Marine Mammal Commission (recently 

modified to occur in conjunction with 

the annual monitoring technical review 

meeting). 

Preliminary Negligible Impact Analysis 

and Determination 

Negligible Impact Analysis 

Introduction 

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 mortality, serious injury, and 

Level A or Level B harassment (as 

presented in Tables 41 and 42), NMFS 

considers other factors, such as the 

likely nature of any responses (e.g., 

intensity, duration), the context of any 

responses (e.g., critical reproductive 

time or location, migration), 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’s 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 environmental baseline 

(e.g., as reflected in the regulatory status 

of the species, population size and 

growth rate where known, other ongoing 

sources of human-caused mortality, 

ambient noise levels, and specific 

consideration of take by Level A 

harassment or serious injury or 

mortality (hereafter referred to as M/SI) 

previously authorized for other NMFS 

activities). 

In the Estimated Take section, we 

identified the subset of potential effects 

that would be expected to rise to the 

level of takes, and then identified the 

number of each of those takes that we 

believe could occur (mortality) or are 

likely to occur (harassment) based on 

the methods described. The impact that 

any given take will have is dependent 

on many case-specific factors that need 

to be considered in the negligible 

impact analysis (e.g., the context of 

behavioral exposures such as duration 

or intensity of an disturbance, the health 

of impacted animals, the status of a 

species that incurs fitness-level impacts 

to individuals, etc.). Here, we evaluate 

the likely impacts of the enumerated 

harassment takes that are proposed for 

authorization and anticipated to occur 

in this rule, in the context of the specific 

circumstances surrounding these 

predicted takes. We also include a 

specific assessment of serious injury or 

mortality takes that could occur, as well 

as consideration of the traits and 

statuses of the affected species and 

stocks. Last, we pull all of this 

information, as well as other more taxaspecific information and the mitigation 

measure effectiveness, together into 

group-specific discussions that support 

our negligible impact conclusions for 

each stock. 

Harassment 

The Navy’s Specified Activities 

reflects representative levels/ranges of 

training and testing activities, 

accounting for the natural fluctuation in 

training, testing, and deployment 

schedules. This approach is 

representative of how Navy’s activities 

are conducted over any given year over 

any given five-year period. Specifically, 

to calculate take, the Navy provided a 

range of levels for each activity/source 

type for a year—they used the maximum 

annual level to calculate annual takes, 

and they used the sum of three nominal 

years (average level) and two maximum 

years to calculate five-year takes for 

each source type. The Specified 

Activities section contains a more 

realistic annual representation of 

activities, but includes years of a higher 

maximum amount of training and 

testing to account for these fluctuations. 

There may be some flexibility in the 

exact number of hours, items, or 

detonations that may vary from year to 

year, but take totals would not exceed 

the five-year totals indicated in Tables 

41 and 42. We base our analysis and 

negligible impact determination (NID) 

on the maximum number of takes that 

could occur or are likely to occur, 

although, as stated before, the number of 

takes are only a part of the analysis, 

which includes extensive qualitative 

consideration of other contextual factors 

that influence the degree of impact of 

the takes on the affected individuals. To 

avoid repetition, we provide some 

general analysis immediately below that 

applies to all the species listed in Tables 

41 and 42, given that some of the 

anticipated effects of the Navy’s training 

and testing activities on marine 


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mammals are expected to be relatively 

similar in nature. However, below that, 

we break our analysis into species (and/ 

or stock), or groups of species (and the 

associated stocks) where relevant 

similarities exist, to provide more 

specific information related to the 

anticipated effects on individuals of a 

specific stock or where there is 

information about the status or structure 

of any species that would lead to a 

differing assessment of the effects on the 

species or stock. 

The Navy’s harassment take request is 

based on its model and quantitative 

assessment of mitigation, which NMFS 

believes appropriately predicts that 

amount of harassment that is likely to 

occur. In the discussions below, the 

‘‘acoustic analysis’’ refers to the Navy’s 

modeling results and quantitative 

assessment of mitigation. The model 

calculates sound energy propagation 

from sonar, other active acoustic 

sources, and explosives during naval 

activities; the sound or impulse received 

by animat dosimeters representing 

marine mammals distributed in the area 

around the modeled activity; and 

whether the sound or impulse energy 

received by a marine mammal exceeds 

the thresholds for effects. Assumptions 

in the Navy model intentionally err on 

the side of overestimation when there 

are unknowns. Naval activities are 

modeled as though they would occur 

regardless of proximity to marine 

mammals, meaning that no mitigation is 

considered (e.g., no power down or shut 

down) and without any avoidance of the 

activity by the animal. The final step of 

the quantitative analysis of acoustic 

effects, which occurs after the modeling, 

is to consider the implementation of 

mitigation and the possibility that 

marine mammals would avoid 

continued or repeated sound exposures. 

NMFS provided input to, and concurred 

with, the Navy on this process and the 

Navy’s analysis, which is described in 

detail in Section 6 of the Navy’s 

rulemaking/LOA application (https://

www.fisheries.noaa.gov/;national/ 

marine-mammal-protection/incidentaltake-authorizations-military-readinessactivities), was used to quantify 

harassment takes for this rule. 

Generally speaking, the Navy and 

NMFS anticipate more severe effects 

from takes resulting from exposure to 

higher received levels (though this is in 

no way a strictly linear relationship for 

behavioral effects throughout species, 

individuals, or circumstances) and less 

severe effects from takes resulting from 

exposure to lower received levels. 

However, there is also growing evidence 

of the importance of distance in 

predicting marine mammal behavioral 

response to sound—i.e., sounds of a 

similar level emanating from a more 

distant source have been shown to be 

less likely to evoke a response of equal 

magnitude (DeRuiter 2012). The 

estimated number of Level A and Level 

B takes does not equate to the number 

of individual animals the Navy expects 

to harass (which is lower), but rather to 

the instances of take (i.e., exposures 

above the Level A and Level B 

harassment threshold) that are 

anticipated to occur over the five-year 

period. These instances may represent 

either brief exposures (seconds or 

minutes) or, in some cases, longer 

durations of exposure within a day. 

Some individuals may experience 

multiple instances of take (meaning over 

multiple days) over the course of the 

year, while some members of a species 

or stock may not experience take at all 

which means that the number of 

individuals taken is smaller than the 

total estimated takes. In other words, 

where the instances of take exceed the 

number of individuals in the 

population, repeated takes (on more 

than one day) of some individuals are 

predicted. Generally speaking, the 

higher the number of takes as compared 

to the population abundance, the more 

repeated takes of individuals are likely, 

and the higher the actual percentage of 

individuals in the population that are 

likely taken at least once in a year. We 

look at this comparative metric to give 

us a relative sense across species/stocks 

of where larger portions of the stocks are 

being taken by Navy activities and 

where there is a higher likelihood that 

the same individuals are being taken 

across multiple days and where that 

number of days might be higher. In the 

ocean, the use of sonar and other active 

acoustic sources is often transient and is 

unlikely to repeatedly expose the same 

individual animals within a short 

period, for example within one specific 

exercise, however, some repeated 

exposures across different activities 

could occur over the year, especially 

where events occur in generally the 

same area with more resident species. In 

short, we expect that the total 

anticipated takes represent exposures of 

a smaller number of individuals of 

which some were exposed multiple 

times, but based on the nature of the 

Navy activities and the movement 

patterns of marine mammals, it is 

unlikely any particular subset would be 

taken over more than a few sequential 

days—i.e., where repeated takes of 

individuals are likely to occur, they are 

more likely to result from nonsequential exposures from different 

activities and marine mammals are not 

predicted to be taken for more than a 

few days in a row, at most. As described 

elsewhere, the nature of the majority of 

the exposures would be expected to be 

of a less severe nature and based on the 

numbers it is still likely that any 

individual exposed multiple times is 

still only taken on a small percentage of 

the days of the year. The greater 

likelihood is that not every individual is 

taken, or perhaps a smaller subset is 

taken with a slightly higher average and 

larger variability of highs and lows, but 

still with no reason to think that any 

individuals would be taken every day 

for months out of the year, much less on 

sequential days. 

Depending on the location, duration, 

and frequency of activities, along with 

the distribution and movement of 

marine mammals, individual animals 

may be exposed to impulse or nonimpulse sounds at or above the Level A 

and Level B harassment threshold on 

multiple days. However, the Navy is 

currently unable to estimate the number 

of individuals that may be taken during 

training and testing activities. The 

model results estimate the total number 

of takes that may occur to a smaller 

number of individuals. 

Some of the lower level physiological 

stress responses (e.g., orientation or 

startle response, change in respiration, 

change in heart rate) discussed earlier 

would also likely co-occur with the 

predicted harassments, although these 

responses are more difficult to detect 

and fewer data exist relating these 

responses to specific received levels of 

sound. Level B takes, then, may have a 

stress-related physiological component 

as well; however, we would not expect 

the Navy’s generally short-term, 

intermittent, and (typically in the case 

of sonar) transitory activities to create 

conditions of long-term, continuous 

noise leading to long-term physiological 

stress responses in marine mammals. 

The estimates calculated using the 

behavioral response function do not 

differentiate between the different types 

of behavioral responses that rise to the 

level of Level B harassments. As 

described in the Navy’s application, the 

Navy identified (with NMFS’s input) the 

types of behaviors that would be 

considered a take (moderate behavioral 

responses as characterized in Southall et 

al., 2007 (e.g., altered migration paths or 

dive profiles, interrupted nursing 

breeding or feeding, or avoidance) that 

also would be expected to continue for 

the duration of an exposure) and then 

compiled the available data indicating 

at what received levels and distances 

those responses have occurred, and 

used the indicated literature to build 

biphasic behavioral response curves that 


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are used to predict how many instances 

of behavioral take occur in a day. Nor 

do the estimates provide information 

regarding the potential fitness or other 

biological consequences of the reactions 

on the affected individuals. We 

therefore consider the available activityspecific, environmental, and speciesspecific information to determine the 

likely nature of the modeled behavioral 

responses and the potential fitness 

consequences for affected individuals. 

Use of sonar and other transducers 

would typically be transient and 

temporary. The majority of acoustic 

effects to mysticetes from sonar and 

other active sound sources during 

testing and training activities would be 

primarily from ASW events. It is 

important to note although ASW is one 

of the warfare areas of focus during 

MTEs, there are significant periods 

when active ASW sonars are not in use. 

Nevertheless, behavioral reactions are 

assumed more likely to be significant 

during MTEs than during other ASW 

activities due to the duration (i.e., 

multiple days), scale (i.e., multiple 

sonar platforms), and use of highpower 

hull-mounted sonar in the MTEs. In 

other words, in the range of potential 

behavioral effects that might expect to 

be part of a response that qualifies as an 

instance take (which by nature of the 

way it is modeled/counted, occurs 

within one day), the less severe end 

might include exposure to 

comparatively lower levels of a sound, 

at a detectably greater distance from the 

animal, for a few or several minutes, 

and that could result in a behavioral 

response such as avoiding an area that 

an animal would otherwise have chosen 

to move through or feed in for some 

amount of time or breaking off one or a 

few feeding bouts. The more severe end, 

which occurs a smaller amount of the 

time (when the animal gets close 

enough to the source to receive a 

comparatively higher level, is exposed 

continuously to one source for a longer 

time, or is exposed intermittently to 

different sources throughout a day) 

might result in an animal having a more 

severe flight response and leaving a 

larger area for a day or more or 

potentially losing feeding opportunities 

for a day. To help assess this, for sonar 

(LFAS/MFAS/HFAS) used in the HSTT 

Study Area, the Navy provided 

information estimating the percentage of 

animals that may exhibit a significant 

behavior response under each 

behavioral response function that would 

occur within 6-dB increments 

(percentages discussed below in the 

Group and Species-Specific Analysis 

section). As mentioned above, all else 

being equal, an animal’s exposure to a 

higher received level is more likely to 

result in a behavioral response that is 

more likely to lead to adverse effects, 

which could more likely accumulate to 

impacts on reproductive success or 

survivorship of the animal, but as 

mentioned previously other contextual 

factors (such as distance) are important 

also. The majority of Level B takes are 

expected to be in the form of milder 

responses (i.e., lower-level exposures 

that still rise to the level of take, but 

would likely be less severe in the range 

of responses that qualify as take) of a 

generally shorter duration. We 

anticipate more severe effects from takes 

when animals are exposed to higher 

received levels or at closer proximity to 

the source. These discussions are 

presented within each species group 

below in the Group and SpeciesSpecific Analysis section. Specifically, 

given a range of behavioral responses 

that may be classified as Level B 

harassment, to the degree that higher 

received levels are expected to result in 

more severe behavioral responses, only 

a smaller percentage of the anticipated 

Level B harassment (see the Group and 

Species-Specific Analysis section below 

for more detailed information) from 

Navy activities might necessarily be 

expected to potentially result in more 

severe responses. To fully understand 

the likely impacts of the predicted/ 

authorized take on an individual (i.e., 

what is the likelihood or degree of 

fitness impacts), one must look closely 

at the available contextual information, 

such as the duration of likely exposures 

and the likely severity of the exposures 

(e.g., will they occur from high level 

hull-mounted sonars or smaller less 

impactful sources). Moore and Barlow 

(2013) emphasizes the importance of 

context (e.g., behavioral state of the 

animals, distance from the sound 

source, etc.) in evaluating behavioral 

responses of marine mammals to 

acoustic sources. 

Diel Cycle 

As noted previously, many animals 

perform vital functions, such as feeding, 

resting, traveling, and socializing on a 

diel cycle (24-hour cycle). Behavioral 

reactions to noise exposure (when 

taking place in a biologically important 

context, such as disruption of critical 

life functions, displacement, or 

avoidance of important habitat) are 

more likely to be significant if they last 

more than one diel cycle or recur on 

subsequent days (Southall et al., 2007). 

Henderson et al., 2016 found that 

ongoing smaller scale events had little 

to no impact on foraging dives for 

Blainville’s beaked whale, while multiday training events may decrease 

foraging behavior for Blainville’s beaked 

whale (Manzano-Roth et al., 2016). 

Consequently, a behavioral response 

lasting less than one day and not 

recurring on subsequent days is not 

considered severe unless it could 

directly affect reproduction or survival 

(Southall et al., 2007). Note that there is 

a difference between multiple-day 

substantive behavioral reactions and 

multiple-day anthropogenic activities. 

For example, just because an at-sea 

exercise lasts for multiple days does not 

necessarily mean that individual 

animals are either exposed to those 

exercises for multiple days or, further, 

exposed in a manner resulting in a 

sustained multiple day substantive 

behavioral response. Large multi-day 

Navy exercises such as ASW activities, 

typically include vessels that are 

continuously moving at speeds typically 

10–15 kn, or higher, and likely cover 

large areas that are relatively far from 

shore (typically more than 3 nmi from 

shore) and in waters greater than 600 ft 

deep, in addition to the fact that marine 

mammals are moving as well, which 

would make it unlikely that the same 

animal could remain in the immediate 

vicinity of the ship for the entire 

duration of the exercise. Further, the 

Navy does not necessarily operate active 

sonar the entire time during an exercise. 

While it is certainly possible that these 

sorts of exercises could overlap with 

individual marine mammals multiple 

days in a row at levels above those 

anticipated to result in a take, because 

of the factors mentioned above, it is 

considered unlikely for the majority of 

takes. However, it is also worth noting 

that the Navy conducts many different 

types of noise-producing activities over 

the course of the year and it is likely 

that some marine mammals will be 

exposed to more than one and taken on 

multiple days, even if they are not 

sequential. 

Durations of Navy activities utilizing 

tactical sonar sources and explosives 

vary and are fully described in 

Appendix A of the HSTT DEIS/OEIS. 

Sonar used during ASW would impart 

the greatest amount of acoustic energy 

of any category of sonar and other 

transducers analyzed in the Navy’s 

rulemaking/LOA application and 

included hull-mounted, towed, 

sonobuoy, helicopter dipping, and 

torpedo sonars. Most ASW sonars are 

MFAS (1–10 kHz); however, some 

sources may use higher or lower 

frequencies. ASW training activities 

using hull mounted sonar proposed for 

the HSTT Study Area generally last for 

only a few hours. Some ASW training 


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and testing can generally last for 2–10 

days, or as much as 21 days for an MTELarge Integrated ASW (see Table 4). For 

these multi-day exercises there will be 

extended intervals of non-activity in 

between active sonar periods. Because 

of the need to train in a large variety of 

situations, the Navy does not typically 

conduct successive ASW exercises in 

the same locations. Given the average 

length of ASW exercises (times of sonar 

use) and typical vessel speed, combined 

with the fact that the majority of the 

cetaceans would not likely remain in 

proximity to the sound source, it is 

unlikely that an animal would be 

exposed to LFAS/MFAS/HFAS at levels 

or durations likely to result in a 

substantive response that would then be 

carried on for more than one day or on 

successive days. 

Most planned explosive events are 

scheduled to occur over a short duration 

(1–8 hours); however, the explosive 

component of the activity only lasts for 

minutes (see Tables 4 through 7). 

Although explosive exercises may 

sometimes be conducted in the same 

general areas repeatedly, because of 

their short duration and the fact that 

they are in the open ocean and animals 

can easily move away, it is similarly 

unlikely that animals would be exposed 

for long, continuous amounts of time. 

Although SINKEXs may last for up to 48 

hrs (4–8 hrs, possibly 1–2 days), they 

are almost always completed in a single 

day and only one event is planned 

annually for the HSTT training 

activities. They are stationary and 

conducted in deep, open water (where 

fewer marine mammals would typically 

be expected to be randomly 

encountered), and they have rigorous 

monitoring (i.e., during the activity, 

conduct passive acoustic monitoring 

and visually observe for marine 

mammals 90 min prior to the first firing, 

during the event, and 2 hrs after sinking 

the vessel) and shutdown procedures all 

of which make it unlikely that 

individuals would be exposed to the 

exercise for extended periods or on 

consecutive days. 

Last, as described previously, Navy 

modeling uses the best available science 

to predict the instances of exposure 

above certain acoustic thresholds, 

which are equated, as appropriate, to 

harassment takes (and further corrected 

to account for mitigation and 

avoidance). As further noted, for active 

acoustics, it is more challenging to parse 

out the number of individuals taken 

from this larger number of instances. 

One method that NMFS can use to help 

better understand the overall scope of 

the impacts is to compare these total 

instances of take against the abundance 

of that stock. For example, if there are 

100 takes in a population of 100, one 

can assume either that every individual 

was exposed above acoustic thresholds 

in no more than one day, or that some 

smaller number were exposed in one 

day but a few of those individuals were 

exposed multiple days within a year. 

Where the instances of take exceed 100 

percent of the population, multiple 

takes of some individuals are predicted 

to occur within a year. Generally 

speaking, the higher the number of takes 

as compared to the population 

abundance, the more multiple takes of 

individuals are likely, and the higher 

the actual percentage of individuals in 

the population that are likely taken at 

least once in a year. We look at this 

comparative metric to give us a relative 

sense across species/stocks of where 

larger portions of the stocks are being 

taken by Navy activities and where 

there is a higher likelihood that the 

same individuals are being taken across 

multiple days and where that number of 

days might be higher. At a minimum, it 

provides a relative picture of the scale 

of impacts to each stock. 

In the ocean, unlike a modeling 

simulation with static animals, the use 

of sonar and other active acoustic 

sources is often transient, and is 

unlikely to repeatedly expose the same 

individual animals within a short 

period, for example within one specific 

exercise. However, some repeated 

exposures across different activities 

would likely occur over the year, 

especially where numerous activities 

occur in generally the same area (for 

example on instrumented ranges) with 

more resident species. In short, we 

expect that the total anticipated takes 

represent exposures of a smaller number 

of individuals of which some would be 

exposed multiple times, but based on 

the nature of the Navy’s activities and 

the movement patterns of marine 

mammals, it is unlikely that any 

particular subset would be taken over 

more than a few sequential days—i.e., 

where repeated takes of individuals are 

likely to occur. They are more likely to 

result from non-sequential exposures 

from different activities and the majority 

of marine mammal stocks are not 

predicted to be taken for more than a 

few days in a row. 

When calculating the proportion of a 

population affected by takes (e.g., the 

number of takes divided by population 

abundance), it is important to choose an 

appropriate population estimate to make 

the comparison. The SARs provide the 

official population estimate for a given 

species or stock in U.S. waters in a 

given year (and are typically based 

solely on the most recent survey data). 

However, the Study Area encompasses 

large areas of ocean space outside U.S. 

waters; therefore, the SARs do not 

account for the total abundance in the 

Study Area. Additionally, the SARs are 

not to the only information used to 

estimate takes, instead modeled density 

layers are used, which incorporate the 

SAR surveys and other survey data. If 

takes are calculated from another 

dataset (for example a broader sample of 

survey data) and compared to the 

population estimate from the SARs, it 

may distort the percent of the 

population affected because of different 

population baselines. The estimates 

found in NMFS’s SARs remain the 

official estimates of stock abundance 

where they are current. These estimates 

are typically generated from the most 

recent shipboard and/or aerial surveys 

conducted. Studies based on abundance 

and distribution surveys restricted to 

U.S. waters are unable to detect 

temporal shifts in distribution beyond 

U.S. waters that might account for any 

changes in abundance within U.S. 

waters. In some cases, NMFS’s 

abundance estimates show substantial 

year-to-year variability. However, for 

highly migratory species (e.g., large 

whales) or those whose geographic 

distribution extends well beyond the 

boundaries of the Navy’s study area 

(e.g., population with distribution along 

the entire California Current versus just 

SOCAL), comparisons to the SAR may 

be more appropriate. This is because the 

Navy’s acoustic modeling process does 

not horizontally move animats, and 

therefore does not account for 

immigration and emigration within the 

study area. For instance, while it may be 

accurate that the abundance of animals 

in Southern California at any one time 

for a particular species is 200 

individuals, if the species is highly 

migratory or has large daily home 

ranges, it is not likely that the same 200 

individuals would be present every day. 

A good descriptive example is blue 

whales, which tagging data have shown 

traverse the SOCAL area in a few days 

to weeks on their migrations. Therefore, 

at any one time there may be a stable 

number of animals, but over the course 

of the entire year the entire population 

may cycle through SOCAL. Therefore, 

when comparing the estimated takes to 

an abundance, in this case the SAR, 

which represents the total population, 

may be more appropriate than the 

Navy’s modeled abundance for SOCAL. 

In each of the species write-ups for the 

negligible impact assessment we explain 

which abundance was used for making 

the comparison of takes to the impacts 

to the population. 


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NMFS’s Southwest Fisheries Science 

Center derived densities for the Navy, 

and NMFS supports, the use of spatially 

and temporally explicit density models 

that vary in space and time to estimate 

their potential impacts to species. See 

the U.S. Navy Marine Species Density 

Database Phase III Hawaii-Southern 

California Training and Testing Area 

Technical Report to learn more on how 

the Navy selects density information 

and the models selected for individual 

species. These models may better 

characterize how Navy impacts can vary 

in space and time but often predict 

different population abundances than 

the SARs. 

Models may predict different 

population abundances for many 

reasons. The models may be based on 

different data sets or different temporal 

predictions may be made. The SARs are 

often based on single years of NMFS 

surveys, whereas the models used by 

the Navy generally include multiple 

years of survey data from NMFS, the 

Navy, and other sources. To present a 

single, best estimate, the SARs often use 

a single season survey where they have 

the best spatial coverage (generally 

summer). Navy models often use 

predictions for multiple seasons, where 

appropriate for the species, even when 

survey coverage in non-summer seasons 

is limited, to characterize impacts over 

multiple seasons as Navy activities may 

occur in any season. Predictions may be 

made for different spatial extents. Many 

different, but equally valid, habitat and 

density modeling techniques exist and 

these can also be the cause of 

differences in population predictions. 

Differences in population estimates may 

be caused by a combination of these 

factors. Even similar estimates should 

be interpreted with caution and 

differences in models be fully 

understood before drawing conclusions. 

The Navy Study Area covers a broad 

area off of Hawaii and Southern 

California, and the Navy has tried to 

find density estimates for this entire 

area, where appropriate given species 

distributions. However, only a small 

number of Navy training and testing 

activities occur outside of the U.S. EEZ. 

Because of the differences in the 

availability of data in the U.S. EEZ 

versus outside (which results in more 

accurate density and abundance 

estimates inside the U.S. EEZ) and the 

fact that activities and takes are more 

concentrated in the U.S. EEZ, NMFS 

chose to look at how estimated 

instances of take compare to predicted 

abundance both within the U.S. EEZ 

and across the entire study area to help 

better understand, at least in a relative 

sense, what the estimated instances of 

take tell us about either the likely 

number of individuals taken, and/or 

over how many days they might be 

taken. These comparisons are 

undertaken below in the taxa-specific 

sections. 

Temporary Threshold Shift 

NMFS and the Navy have estimated 

that some individuals of some species of 

marine mammals may sustain some 

level of TTS from active sonar. As 

mentioned previously, TTS can last 

from a few minutes to days, be of 

varying degree, and occur across various 

frequency bandwidths, all of which 

determine the severity of the impacts on 

the affected individual, which can range 

from minor to more severe. Tables 69– 

81 indicate the amounts of TTS that 

may be incurred by different stocks from 

exposure to acoustic sources (sonar, air 

guns, pile driving) and explosives. The 

TTS sustained by an animal is primarily 

classified by three characteristics: 

1. Frequency—Available data (of midfrequency hearing specialists exposed to 

mid- or high-frequency sounds; Southall 

et al., 2007) suggest that most TTS 

occurs in the frequency range of the 

source up to one octave higher than the 

source (with the maximum TTS at 1⁄2

octave above). The Navy’s MF sources 

the 1–10 kHz frequency band, which 

suggests that if TTS were to be induced 

by any of these MF sources would be in 

a frequency band somewhere between 

approximately 2 and 20 kHz. There are 

fewer hours of HF source use and the 

sounds would attenuate more quickly, 

plus they have lower source levels, but 

if an animal were to incur TTS from 

these sources, it would cover a higher 

frequency range (sources are between 10 

and 100 kHz, which means that TTS 

could range up to 200 kHz; however, HF 

systems are typically used less 

frequently and for shorter time periods 

than surface ship and aircraft MF 

systems, so TTS from these sources is 

even less likely). TTS from explosives 

would be broadband. 

2. Degree of the shift (i.e., by how 

many dB the sensitivity of the hearing 

is reduced)—Generally, both the degree 

of TTS and the duration of TTS will be 

greater if the marine mammal is exposed 

to a higher level of energy (which would 

occur when the peak dB level is higher 

or the duration is longer). The threshold 

for the onset of TTS was discussed 

previously in this proposed rule. An 

animal would have to approach closer 

to the source or remain in the vicinity 

of the sound source appreciably longer 

to increase the received SEL, which 

would be difficult considering the 

Lookouts and the nominal speed of an 

active sonar vessel (10–15 kn). In the 

TTS studies (see Threshold Shift 

section), some using exposures of 

almost an hour in duration or up to 217 

SEL, most of the TTS induced was 15 

dB or less, though Finneran et al. (2007) 

induced 43 dB of TTS with a 64-second 

exposure to a 20 kHz source. However, 

since any hull-mounted sonar such as 

the SQS–53 (MFAS), emits a ping 

typically every 50 sec, incurring those 

levels of TTS is highly unlikely. 

3. Duration of TTS (recovery time)— 

In the TTS laboratory studies (see 

Threshold Shift) section), some using 

exposures of almost an hour in duration 

or up to 217 SEL, almost all individuals 

recovered within 1 day (or less, often in 

minutes), although in one study 

(Finneran et al., 2007), recovery took 4 

days. 

Based on the range of degree and 

duration of TTS reportedly induced by 

exposures to non-pulse sounds of 

energy higher than that to which freeswimming marine mammals in the field 

are likely to be exposed during LFAS/ 

MFAS/HFAS training and testing 

exercises in the HSTT Study Area, it is 

unlikely that marine mammals would 

ever sustain a TTS from MFAS that 

alters their sensitivity by more than 20 

dB for more than a few hours (and any 

incident of TTS would likely be far less 

severe due to the short duration of the 

majority of the events and the speed of 

a typical vessel). Also, for the same 

reasons discussed in the Diel Cycle 

section, and because of the short 

distance within which animals would 

need to approach the sound source, it is 

unlikely that animals would be exposed 

to the levels necessary to induce TTS in 

subsequent time periods such that their 

recovery is impeded. Additionally, 

though the frequency range of TTS that 

marine mammals might sustain would 

overlap with some of the frequency 

ranges of their vocalization types, the 

frequency range of TTS from MFAS (the 

source from which TTS would most 

likely be sustained because the higher 

source level and slower attenuation 

make it more likely that an animal 

would be exposed to a higher received 

level) would not usually span the entire 

frequency range of one vocalization 

type, much less span all types of 

vocalizations or other critical auditory 

cues. If impaired, marine mammals 

would typically be aware of their 

impairment and would sometimes able 

to implement behaviors to compensate 

(see Acoustic Masking or 

Communication Impairment section), 

though these compensations may incur 

energetic costs. 

Therefore, even though the models 

show that the affected species and 

stocks will experience Level B 


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harassment at the levels shown in 

Tables 69–81 and that much of that 

harassment will occur in the form of 

TTS, the actual TTS that will result 

from Navy’s activities is expected to be 

both mild and short-term for the 

majority of exposed animals. While the 

TTS experienced by some animals 

would overlap with the frequency 

ranges of their vocalizations, it is 

unlikely that it would affect all 

vocalizations and other critical auditory 

clues, and impaired animals may be 

able to compensate until they have 

recovered. For these reasons, the 

majority of the Level B harassment in 

the form of TTS shown in Tables 69–81 

is expected to be short-term and not to 

have significant impacts on affected 

animals in a manner that would affect 

reproduction or survival. 

Acoustic Masking or Communication 

Impairment 

Masking only occurs during the time 

of the signal (and potential secondary 

arrivals of indirect rays), versus TTS, 

which continues beyond the duration of 

the signal. Standard MFAS typically 

pings every 50 seconds for hullmounted sources. Hull-mounted antisubmarine sonars can also be used in an 

object detection mode known as 

‘‘Kingfisher’’ mode (e.g., used on vessels 

when transiting to and from port), pulse 

length is shorter, but pings are much 

closer together in both time and space, 

since the vessel goes slower when 

operating in this mode. For the majority 

of sources, the pulse length is 

significantly shorter than hull-mounted 

active sonar, on the order of several 

microseconds to tens of microseconds. 

For hull-mounted active sonar, though 

some of the vocalizations that marine 

mammals make are less than one second 

long, there is only a 1 in 50 chance that 

they would occur exactly when the ping 

was received, and when vocalizations 

are longer than one second, only parts 

of them are masked. Alternately, when 

the pulses are only several 

microseconds long, the majority of most 

animals’ vocalizations would not be 

masked. 

Most ASW sonars and 

countermeasures use MF frequencies 

and a few use LF and HF frequencies. 

Most of these sonar signals are limited 

in the temporal, frequency, and spatial 

domains. The duration of most 

individual sounds is short, lasting up to 

a few seconds each. Very few systems 

operate with higher duty cycles or 

nearly continuously, but typically use 

lower power. Nevertheless, masking 

may be more prevalent at closer ranges 

to these high-duty cycle and continuous 

active sonar systems. Most ASW 

activities are geographically dispersed 

and last for only a few hours, often with 

intermittent sonar use even within this 

period. Most ASW sonars also have a 

narrow frequency band (typically less 

than one-third octave). These factors 

reduce the likelihood of sources causing 

significant masking in mysticetes. HF 

sonars are typically used for mine 

hunting, navigation, and object 

detection, HF (greater than 10 kHz) 

sonars fall outside of the best hearing 

and vocalization ranges of mysticetes. 

Furthermore, HF (above 10 kHz) 

attenuate more rapidly in the water due 

to absorption than do lower frequency 

signals, thus producing only a small 

zone of potential masking. Masking in 

mysticetes due to exposure to highfrequency sonar is unlikely. Masking 

effects from LFAS/MFAS/HFAS are 

expected to be minimal. If masking or 

communication impairment were to 

occur briefly, it would be in the 

frequency range of MFAS, which 

overlaps with some marine mammal 

vocalizations; however, it would likely 

not mask the entirety of any particular 

vocalization, communication series, or 

other critical auditory cue, because the 

signal length, frequency, and duty cycle 

of the MFAS/HFAS signal does not 

perfectly resemble the characteristics of 

any marine mammal’s vocalizations. 

Masking could occur in mysticetes due 

to the overlap between their lowfrequency vocalizations and the 

dominant frequencies of air gun pulses. 

However, masking in odontocetes or 

pinnipeds is less likely unless the air 

gun activity is in close range when the 

pulses are more broadband. Masking is 

more likely to occur in the presence of 

broadband, relatively continuous noise 

sources such as during vibratory pile 

driving and from vessels. The other 

sources used in Navy training and 

testing, many of either higher 

frequencies (meaning that the sounds 

generated attenuate even closer to the 

source) or lower amounts of operation, 

are similarly not expected to result in 

masking. For the reasons described here, 

any limited masking that could 

potentially occur would be minor and 

short-term and not expected to have 

adverse impacts on reproductive 

success or survivorship. 

PTS From Sonar Acoustic Sources and 

Explosives and Tissue Damage From 

Explosives 

Tables 69–81 indicate the number of 

individuals of each species and stock for 

which Level A harassment in the form 

of PTS resulting from exposure to active 

sonar and/or explosives is estimated to 

occur. Tables 69–81 also indicate the 

number of individuals of each species 

and stock for which Level A harassment 

in the form of tissue damage resulting 

from exposure to explosive detonations 

is estimated to occur. The number of 

individuals to potentially incur PTS 

annually (from sonar and explosives) for 

the predicted species ranges from 0 to 

209 (209 for Dall’s porpoise), but is 

more typically zero or a few up to 18 

(with the exception of a few species i.e., 

short-beaked common dolphin, Kogia 

whales, Dall’s porpoise, California sea 

lion, and Northern elephant seal). The 

number of individuals to potentially 

incur tissue damage from explosives for 

the predicted species ranges from 0 to 

10 (10 for short-beaked common 

dolphin and 9 for California sea lion), 

but is typically zero in most cases. 

Overall the Navy’s model estimated that 

a total 24 marine mammals annually 

would be exposed to explosives during 

training and testing at levels that could 

result in non-auditory injury. Overall, 

takes from Level A harassment (PTS and 

Tissue Damage) account for less than 

one percent of all total takes. 

NMFS believes that many marine 

mammals would deliberately avoid 

exposing themselves to the received 

levels of active sonar necessary to 

induce injury by moving away from or 

at least modifying their path to avoid a 

close approach. Additionally, in the 

unlikely event that an animal 

approaches the sonar-emitting vessel at 

a close distance, NMFS believes that the 

mitigation measures (i.e., shutdown/ 

powerdown zones for active sonar) 

would typically ensure that animals 

would not be exposed to injurious levels 

of sound. Some, but likely not all, of the 

anticipated avoidance and mitigation 

has been accounted for in the Navy’s 

quantitative assessment of mitigation— 

regardless we analyze the impacts of 

those potential takes in case they should 

occur. As discussed previously, the 

Navy utilizes both aerial (when 

available) and passive acoustic 

monitoring (during ASW exercises— 

passive acoustic detections are used as 

a cue for Lookouts’ visual observations 

when passive acoustic assets are already 

participating in an activity) in addition 

to lookouts on vessels to detect marine 

mammals for mitigation 

implementation. 

If a marine mammal is able to 

approach a surface vessel within the 

distance necessary to incur PTS, the 

likely speed of the vessel (nominally 

10–15 kn) would make it very difficult 

for the animal to remain in range long 

enough to accumulate enough energy to 

result in more than a mild case of PTS. 

As mentioned previously and in relation 

to TTS, the likely consequences to the 

health of an individual that incurs PTS 


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can range from mild to more serious 

dependent upon the degree of PTS and 

the frequency band it is in, and many 

animals are able to compensate for the 

shift, although it may include energetic 

costs. We also assume that the acoustic 

exposures sufficient to trigger onset PTS 

(or TTS) would be accompanied by 

physiological stress responses, although 

the sound characteristics that correlate 

with specific stress responses in marine 

mammals are poorly understood. As 

discussed above for Behavioral 

Harassment, we would not expect the 

Navy’s generally short-term, 

intermittent, and (in the case of sonar) 

transitory activities to create conditions 

of long-term, continuous noise leading 

to long-term physiological stress 

responses in marine mammals. 

For explosive activities, the Navy 

implements mitigation measures 

(described in Proposed Mitigation 

Measures) during explosive activities, 

including delaying detonations when a 

marine mammal is observed in the 

mitigation zone. Observing for marine 

mammals during the explosive activities 

will include aerial and passive acoustic 

detection methods (when they are 

available and part of the activity) before 

the activity begins, in order to cover the 

mitigation zones that can range from 

200 yds (183 m) to 2,500 yds (2,286 m) 

depending on the source (e.g., explosive 

sonobuoy, explosive torpedo, explosive 

bombs) and 2.5 nmi for sinking exercise 

(see Tables 48–55). 

Nearly all explosive events will occur 

during daylight hours to improve the 

sightability of marine mammals 

improving mitigation effectiveness. The 

proposed mitigation is expected to 

reduce the likelihood that all of the 

proposed takes will occur. Some, 

though likely not all, of that reduction 

was quantified in the Navy’s 

quantitative assessment of mitigation; 

however, we analyze the type and 

amount of Level A take indicated in 

Tables 41 and 42. Generally speaking, 

the number and degree of potential 

injury are low. 

Therefore, given that the numbers of 

anticipated injury in the form of PTS or 

tissue damage are very low (<18 or 

single digits, respectively), for any given 

stock, with the exception of a few 

species, and the severity of these 

impacts are expected to be on the less 

severe end of what could potentially 

occur because of the factors described 

above, as well as the fact that any PTS 

incurred may overlap with the 

frequency ranges of their vocalizations, 

but is unlikely to affect all vocalizations 

and other critical auditory clues, the 

Level A harassment shown in Tables 

69–81 is not expected to have 

significant or long-term impacts on 

affected animals in a manner that would 

affect reproduction or survival. 

Serious Injury and Mortality 

NMFS proposes to authorize a very 

small number of serious injuries or 

mortalities that could occur in the event 

of a ship strike or as a result of marine 

mammal exposure to explosive 

detonations. We note here that the takes 

from potential ship strikes or explosive 

exposures enumerated below could 

result in non-serious injury, but their 

worse potential outcome (mortality) is 

analyzed for the purposes of the 

negligible impact determination. 

In addition, we discuss here the 

connection between the mechanisms for 

authorizing incidental take under 

section 101(a)(5) for activities, such as 

Navy’s testing and training in the HSTT 

Study Area, and for authorizing 

incidental take from commercial 

fisheries. In 1988, Congress amended 

the MMPA’s provisions for addressing 

incidental take of marine mammals in 

commercial fishing operations. Congress 

directed NMFS to develop and 

recommend a new long-term regime to 

govern such incidental taking (see 

MMC, 1994). The need to develop a 

system suited to the unique 

circumstances of commercial fishing 

operations led NMFS to suggest a new 

conceptual means and associated 

regulatory framework. That concept, 

Potential Biological Removal (PBR), and 

a system for developing plans 

containing regulatory and voluntary 

measures to reduce incidental take for 

fisheries that exceed PBR were 

incorporated as sections 117 and 118 in 

the 1994 amendments to the MMPA. 

PBR is defined in the MMPA (16 

U.S.C. 1362(20)) 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’’ 

(OSP) and is a measure to be considered 

when evaluating the effects of M/SI on 

a marine mammal species or stock. OSP 

is defined by the MMPA (16 U.S.C. 

1362(9)) as ‘‘the number of animals 

which will result in the maximum 

productivity of the population or the 

species, keeping in mind the carrying 

capacity of the habitat and the health of 

the ecosystem of which they form a 

constituent element.’’ A primary goal of 

the MMPA is to ensure that each species 

or stock of marine mammal is 

maintained at or returned to its OSP. 

PBR values are calculated by NMFS as 

the level of annual removal from a stock 

that will allow that stock to equilibrate 

within OSP at least 95 percent of the 

time, and is the product of factors 

relating to the minimum population 

estimate of the stock (Nmin); the 

productivity rate of the stock at a small 

population size; and a recovery factor. 

Determination of appropriate values for 

these three elements incorporates 

significant precaution, such that 

application of the parameter to the 

management of marine mammal stocks 

may be reasonably certain to achieve the 

goals of the MMPA. For example, 

calculation of Nmin incorporates the 

precision and variability associated with 

abundance information and is intended 

to provide reasonable assurance that the 

stock size is equal to or greater than the 

estimate (Barlow et al., 1995). In 

general, the three factors are developed 

on a stock-specific basis in 

consideration of one another in order to 

produce conservative PBR values that 

appropriately account for both 

imprecision that may be estimated, as 

well as potential bias stemming from 

lack of knowledge (Wade, 1998). 

PBR can be used as a consideration of 

the effects of M/SI on a marine mammal 

stock but was applied specifically to 

work within the management 

framework for commercial fishing 

incidental take. PBR cannot be applied 

appropriately outside of the section 118 

regulatory framework for which it was 

designed without consideration of how 

it applies in section 118 and how other 

statutory management frameworks in 

the MMPA differ. PBR was not designed 

as an absolute threshold limiting 

commercial fisheries, but rather as a 

means to evaluate the relative impacts 

of those activities on marine mammal 

stocks. Even where commercial fishing 

is causing M/SI at levels that exceed 

PBR, the fishery is not suspended. 

When M/SI exceeds PBR, NMFS may 

develop a take reduction plan, usually 

with the assistance of a take reduction 

team. The take reduction plan will 

include measures to reduce and/or 

minimize the taking of marine mammals 

by commercial fisheries to a level below 

the stock’s PBR. That is, where the total 

annual human-caused M/SI exceeds 

PBR, NMFS is not required to halt 

fishing activities contributing to total 

M/SI but rather utilizes the take 

reduction process to further mitigate the 

effects of fishery activities via additional 

bycatch reduction measures. PBR is not 

used to grant or deny authorization of 

commercial fisheries that may 

incidentally take marine mammals. 

Similarly, to the extent consideration 

of PBR may be relevant to considering 

the impacts of incidental take from 

activities other than commercial 

fisheries, using it as the sole reason to 

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those activities would be inconsistent 

with Congress’s intent under section 

101(a)(5) and the use of PBR under 

section 118. The standard for 

authorizing incidental take under 

section 101(a)(5) continues to be, among 

other things, whether the total taking 

will have a negligible impact on the 

species or stock. When Congress 

amended the MMPA in 1994 to add 

section 118 for commercial fishing, it 

did not alter the standards for 

authorizing non-commercial fishing 

incidental take under section 101(a)(5), 

acknowledging that negligible impact 

under section 101(a)(5) is a separate 

standard from PBR under section 118. In 

fact, in 1994 Congress also amended 

section 101(a)(5)(E) (a separate 

provision governing commercial fishing 

incidental take for species listed under 

the Endangered Species Act) to add 

compliance with the new section 118 

but kept the requirement for a negligible 

impact finding, showing that the 

determination of negligible impact and 

application of PBR may share certain 

features but are different. 

Since the introduction of PBR, NMFS 

has used the concept almost entirely 

within the context of implementing 

sections 117 and 118 and other 

commercial fisheries managementrelated provisions of the MMPA. The 

MMPA requires that PBR be estimated 

in stock assessment reports and that it 

be used in applications related to the 

management of take incidental to 

commercial fisheries (i.e., the take 

reduction planning process described in 

section 118 of the MMPA and the 

determination of whether a stock is 

‘‘strategic’’ (16 U.S.C. 1362(19))), but 

nothing in the MMPA requires the 

application of PBR outside the 

management of commercial fisheries 

interactions with marine mammals. 

Nonetheless, NMFS recognizes that as 

a quantitative metric, PBR may be useful 

in certain instances as a consideration 

when evaluating the impacts of other 

human-caused activities on marine 

mammal stocks. Outside the commercial 

fishing context, and in consideration of 

all known human-caused mortality, PBR 

can help inform the potential effects of 

M/SI caused by activities authorized 

under 101(a)(5)(A) on marine mammal 

stocks. As noted by NMFS and the 

USFWS in our implementation 

regulations for the 1986 amendments to 

the MMPA (54 FR 40341, September 29, 

1989), the Services consider many 

factors, when available, in making a 

negligible impact determination, 

including, but not limited to, the status 

of the species or stock relative to OSP 

(if known), whether the recruitment rate 

for the species or stock is increasing, 

decreasing, stable, or unknown, the size 

and distribution of the population, and 

existing impacts and environmental 

conditions. To specifically use PBR, 

along with other factors, to evaluate the 

effects of M/SI, we first calculate a 

metric for each species or stock that 

incorporates information regarding 

ongoing anthropogenic M/SI into the 

PBR value (i.e., PBR minus the total 

annual anthropogenic mortality/serious 

injury estimate), which is called 

‘‘residual PBR.’’ (Wood et al., 2012). We 

then consider how the anticipated 

potential incidental M/SI from the 

activities being evaluated compares to 

residual PBR. Anticipated or potential 

M/SI that exceeds residual PBR is 

considered to have a higher likelihood 

of adversely affecting rates of 

recruitment or survival, while 

anticipated M/SI that is equal to or less 

than residual PBR has a lower 

likelihood (both examples given without 

consideration of other types of take, 

which also obviously factor into a 

negligible impact determination). In 

such cases where the anticipated M/SI 

is near, at, or above PBR, consideration 

of other factors, including those 

outlined above as well as mitigation and 

other factors (positive or negative), is 

especially important to assessing 

whether the M/SI will have a negligible 

impact on the stock. As described 

above, PBR is a conservative metric and 

is not intended to be used as a solid cap 

on mortality—accordingly, impacts from 

M/SI that exceed PBR may still 

potentially be found to be negligible in 

light of other factors that offset concern, 

especially when robust mitigation and 

adaptive management provisions are 

included. 

Alternately, for a species or stock with 

incidental M/SI less than 10 percent of 

residual PBR, we consider M/SI from 

the specified activities to represent an 

insignificant incremental increase in 

ongoing anthropogenic M/SI that alone 

(i.e., in the absence of any other take) 

cannot affect annual rates of recruitment 

and survival. In a prior incidental take 

rulemaking and in the commercial 

fishing context, this threshold is 

identified as the significance threshold, 

but it is more accurately an 

insignificance threshold outside 

commercial fishing because it represents 

the level at which there is no need to 

consider other factors in determining 

the role of M/SI in affecting rates of 

recruitment and survival. Assuming that 

any additional incidental take by 

harassment would not exceed the 

negligible impact level, the anticipated 

M/SI caused by the activities being 

evaluated would have a negligible 

impact on the species or stock. This 

10% was identified as a workload 

simplification consideration to avoid 

the need to provide unnecessary 

additional information when the 

conclusion is relatively obvious, but as 

described above, values above 10 

percent have no particular significance 

associated with them until and unless 

they approach residual PBR. 

Our evaluation of the M/SI for each of 

the species and stocks for which 

mortality could occur follows. In 

addition, all mortality authorized for 

some of the same species or stocks over 

the next several years pursuant to our 

final rulemaking for the NMFS 

Southwest and Pacific Islands Fisheries 

Science Centers has been incorporated 

into the residual PBR. 

We first consider maximum potential 

incidental M/SI from Navy’s ship strike 

analysis for the affected mysticetes and 

sperm whales (see Table 67) and from 

the Navy’s explosive detonations for 

California sea lions and short-beaked 

common dolphin (see Table 68) in 

consideration of NMFS’s threshold for 

identifying insignificant M/SI take (10 

percent of residual PBR (69 FR 43338; 

July 20, 2004)). By considering the 

maximum potential incidental M/SI in 

relation to PBR and ongoing sources of 

anthropogenic mortality, we begin our 

evaluation of whether the potential 

incremental addition of M/SI through 

Navy’s ship strikes and explosive 

detonations may affect the species’ or 

stocks’ annual rates of recruitment or 

survival. We also consider the 

interaction of those mortalities with 

incidental taking of that species or stock 

by harassment pursuant to the specified 

activity. 

Based on the methods discussed 

previously, NMFS believes that mortal 

takes of three large whales over the 

course of the five-year rule, with no 

more than two from any of the following 

species/stocks over the five-year period: 

Gray whale (Eastern North Pacific 

stock), fin whale (CA/OR/WA stock), 

humpback whale (CA/OR/WA stock or 

Mexico DPS), humpback whale (Central 

Pacific stock or Hawaii DPS) and sperm 

whale (Hawaiian stock). Of the mortal 

takes of three large whales that could 

occur, no more than one mortality 

would occur from any of the following 

species/stocks over the five-year period: 

Blue whale (Eastern North Pacific 

stock), Bryde’s whale (Eastern Tropical 

Pacific stock), Bryde’s whale (Hawaiian 

stock), humpback whale (CA/OR/WA 

stock or Central America DPS), minke 

whale (CA/OR/WA stock), minke whale 

(Hawaiian stock), sperm whale (CA/OR/ 

WA stock), sei whale (Hawaiian stock), 

and sei whale (Eastern North Pacific 


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stock). The Navy is not requesting, and 

we do not anticipate, ship strike takes 

to blue whale (Central North Pacific 

stock), fin whale (Hawaiian stock), and 

gray whale (Western North Pacific 

stock) due to their relatively low 

occurrence in the Study Area, in 

particular core HSTT training and 

testing subareas. This means an annual 

average of 0.2 whales from each species 

or stock where one mortality may occur 

or an annual average of 0.4 whales from 

each species or stock where two 

mortalities may occur as described in 

Table 67 (i.e., 1 or 2 takes over 5 years 

divided by 5 to get the annual number) 

is proposed for authorization. 

The Navy has also requested a small 

number of takes by serious injury or 

mortality from explosives. To calculate 

the annual average of mortalities for 

explosives in Table 68 we used the same 

method as described for vessel strikes. 

The annual average is the number of 

takes divided by five years to get the 

annual number. 

TABLE 67—SUMMARY INFORMATION RELATED TO MORTALITIES REQUESTED FOR SHIP STRIKE, 2018–2023 

Species 

(stock) 

Stock 

abundance 

(Nbest) * 

Annual 

proposed 

take by 

serious 

injury or 

mortality 1

Total 

annual 

M/SI * 2

Fisheries 

interactions 

(Y/N); 

annual 

rate of 

M/SI from 

fisheries 

interactions * 

Vessel 

collisions 

(Y/N); 

annual 

rate of 

M/SI from 

vessel 

collision * 

PBR * 

Residual 

PBR–PBR 

minus 

annual 

M/SI and 

SWFSC 

authorized 

take 

(%) 3

Stock 

trend * 4

Recent 

UME 

(Y/N); 

number 

and 

year 

(since 

2007) 

Fin whale (CA/OR/WA) ........... 9,029 0.4 ≥2.0 Y; ≥2.0 ............... 1.8 81 78 ↑ N 

Gray whale (Eastern N Pacific).20,990 0.4 132 4.25 ................... 2.0 624 492 Stable 

since 

2003 

N 

Humpback whale (CA/OR,WA 

stock or Mexico DPS).

1,918 0.4 ≥6.5 Y; ≥5.3 ............... 1.0 11.0 4.5 ↑ N 

Humpback whale (Central 

North Pacific stock or Hawaii DPS).

10,103 0.4 24 Y; 7.4 ................. 4.7 83 59 ↑ N 

Sperm whale (Hawaiian stock) 3,354 0.4 0.7 0.7 ..................... 0 10.2 9.5 ? N 

Blue whale (Eastern North Pacific stock).1,647 0.2 0.9 0 ........................ 0.9 2.3 1.4 stable Y; 3, 2007. 

Bryde’s whale (Eastern Tropical Pacific stock).unknown 0.2 0.2 unknown ............ 0.2 undet NA ? N 

Bryde’s whale (Hawaiian 

stock).

798 0.2 0 0 ........................ 0 6.3 6.3 ? N 

Humpback whale (CA/OR/WA 

stock or Central America 

DPS).

1,918 0.4 ≥6.5 Y; ≥5.3 ............... 1.0 11.0 4.5 ↑ N 

Minke whale (CA/OR/WA 

stock).

636 0.2 ≥1.3 ≥1.3 ................... 0 3.5 2.2 ? N 

Minke whale (Hawaiian stock) unknown 0.2 0 0 ........................ 0 undet NA ? N 

Sperm whale (CA/OR/WA 

stock).

2,106 0.2 1.7 1.7 ..................... 0 2.7 1.0 ? N 

Sei whale (Hawaiian stock) .... 178 0.2 0.2 0.2 ..................... 0 0.2 0 ? N 

Sei whale (Eastern N Pacific 

stock).

519 0.2 0 0 ........................ 0 0.75 0.75 ? N 

* Presented in the SARS. 

1This column represent the annual take by serious injury or mortality by vessel collision and was calculated by the number of mortalities proposed for authorization 

divided by five years (the length of the rule and LOAs). 2This column represents the total number of incidents of M/SI that could potentially accrue to the specified species or stock. This number comes from the SAR, but 

deducts the takes accrued from either Navy strikes or SWFSC takes to ensure not double-counted against PBR. However, for these species, there were no takes 

from either Navy or SWFSC to deduct that would be considered double-counting. 3This value represents the calculated PBR less the average annual estimate of ongoing anthropogenic mortalities (i.e., total annual human-caused M/SI, which is 

presented in the SARs). 4See relevant SARs for more information regarding stock status and trends. 

The following species are being 

requested for mortality takes from 

explosions. A total of 10 mortalities: 4 

California sea lions and 6 short-beaked 

common dolphins over the 5-year 

period (therefore 0.8 mortalities 

annually for California sea lions and 1.2 

mortalities annually for short-beaked 

common dolphin) are described in 

Table 68. 

TABLE 68—SUMMARY INFORMATION RELATED TO MORTALITIES FROM EXPLOSIVES, 2018–2023 

Species 

(stock) 

Stock 

abundance 

(Nbest) * 

Annual 

proposed 

take by 

serious 

injury or 

mortality * 1

Total 

annual 

M/SI * 2

Fisheries 

interactions 

(Y/N); 

annual 

rate of 

M/SI from 

fisheries 

interactions * 

PBR * 

SWFSC 

authorized 

take 

(annually) 3

Residual 

PBR–PBR 

minus 

annual 

M/SI and 

SWFSC 4

Stock 

trend * 5

Recent 

UME 

(Y/N); 

number 

and 

year 

California sea lion (U.S.) ......... 296,750 0.8 385 Y; 331 ................ 9,200 6.6 8,808.4 ↑ Y 

Short-beaked common dolphin 

(CA/OR/WA).

969,861 1.2 ≥40 Y; ≥40 ................ 8,393 2.8 8,350.2 ? N 

* Presented in the SARS. 

1This column represents the annual take by serious injury or mortality during explosive detonations and was calculated by the number of mortalities proposed for 

authorization divided by five years (the length of the rule and LOAs). 


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2This column represents the total number of incidents of M/SI that could potentially accrue to the specified species or stock. This number comes from the SAR, but 

deducts the takes accrued from either Navy or NMFS’s Southwest Fisheries Science Center (SWFSC) rulemaking/LOAs takes to ensure not double-counted against 

PBR. 3This column represents annual take authorized for NMFS’s SWFSC rulemaking/LOAs (80 FR 58982). 

4This value represents the calculated PBR less the average annual estimate of ongoing anthropogenic mortalities (i.e., total annual human-caused M/SI, which is 

presented in the SARs). 5See relevant SARs for more information regarding stock status and trends. 

Species With M/SI Below the 

Insignificance Threshold 

As noted above, for a species or stock 

with incidental M/SI less than 10 

percent of residual PBR, we consider 

M/SI from the specified activities to 

represent an insignificant incremental 

increase in ongoing anthropogenic M/SI 

that alone (i.e., in the absence of any 

other take) cannot affect annual rates of 

recruitment and survival. There are no 

known factors that could affect a species 

or stock to the point where anticipated 

M/SI below the insignificance threshold 

could have effects on annual rates of 

recruitment or survival. In this case, as 

shown in Table 67, the following 

species or stocks have anticipated, and 

proposed authorized, M/SI below their 

insignificance threshold and, therefore, 

additional factors are not discussed: Fin 

whale (CA/OR/WA), gray whale 

(Eastern North Pacific), Humpback 

whale (CA/OR/WA stock or Mexico 

DPS), humpback whale (Central Pacific 

stock or Hawaii DPS), sperm whale 

(Hawaiian stock), Bryde’s whale 

(Hawaiian stock), humpback whale (CA/ 

OR/WA stock or Central America DPS), 

minke whale (CA/OR/WA stock), 

California sea lion (U.S.), and shortbeaked common dolphin (CA/OR/WA 

stock). For the remaining six stocks with 

anticipated potential M/SI, how that 

M/SI compares to residual PBR, as well 

as additional factors, as appropriate, are 

discussed below. 

Sperm Whale (California, Oregon, 

Washington Stock) 

For sperm whales (CA/OR/WA stock), 

PBR is currently 2.7 and the total annual 

M/SI is 1.7 and yields a residual PBR of 

1.0. The M/SI value includes incidental 

fishery interaction records of 1.7, and 

records of vessel collisions of 0. The 

proposed authorization of 0.2 

mortalities represents 20 percent of 

residual PBR. Because this value is not 

close to, at, or exceeding residual PBR, 

it means that the proposed M/SI is not 

expected to result in more than a 

negligible impact on this stock, 

however, we still address other factors, 

where available. In regard to mitigation 

measures that may lessen other humancaused mortality in the future, NOAA is 

currently implementing marine 

mammal take reduction measures as 

identified in the Pacific Offshore 

Cetacean Take Reduction Plan 

(including acoustic pingers) to reduce 

bycatch and incidental serious injury 

and mortality of sperm whales, and 

other whales in the CA/OR swordfish 

drift gillnet fishery. There have been 

few observed interactions with sperm 

whales since the fishery was observed, 

both pre and post-take reduction plan, 

however, pingers are within the hearing 

range of sperm whales, and we can infer 

that they may play a part in reducing 

sperm whale interactions in this fishery. 

This information will be considered in 

combination with our assessment of the 

impacts of harassment takes later in the 

section. 

Blue Whale (Eastern North Pacific 

Stock) 

For blue whales (Eastern North Pacific 

stock), PBR is currently set at 2.3 and 

the total annual M/SI of 0.9 yielding a 

residual PBR of 1.4. The M/SI value 

includes incidental fishery interaction 

records of 0, and records of vessel 

collisions of 0.9. The proposed 

authorization of 0.2 represents 14 

percent of residual PBR. Because this 

value is not close to, at, or exceeding 

residual PBR, it means that the 

proposed M/SI is not expected to result 

in more than a negligible impact on this 

stock, however, we still address other 

factors, where available. We note that 

the Eastern North Pacific blue whale 

stock is considered stable. 

In regard to mitigation that may lessen 

other human-caused mortality in the 

future, NOAA is currently 

implementing marine mammal take 

reduction measures as identified in the 

Pacific Offshore Cetacean Take 

Reduction Plan (including the use of 

acoustic pingers) to reduce the bycatch 

of blue whales and other marine 

mammals. In addition, the Channel 

Islands NMS staff coordinates, collects 

and monitors whale sightings in and 

around the Whale Advisory Zone and 

the Channel Islands NMS region. The 

seasonally established Whale Advisory 

Zone spans from Point Arguello to Dana 

Point, including the Traffic Separation 

Schemes in the Santa Barbara Channel 

and San Pedro Channel. Vessels 

transiting the area from June through 

November are recommended to exercise 

caution and voluntarily reduce speed to 

10 kn or less for blue, humpback and fin 

whales. Channel Island NMS observers 

collect information from aerial surveys 

conducted by NOAA, the U.S. Coast 

Guard, California Department of Fish 

and Game, and U.S. Navy chartered 

aircraft. Information on seasonal 

presence, movement and general 

distribution patterns of large whales is 

shared with mariners, NMFS Office of 

Protected Resources, U.S. Coast Guard, 

California Department of Fish and 

Game, the Santa Barbara Museum of 

Natural History, the Marine Exchange of 

Southern California, and whale 

scientists. Real time and historical 

whale observation data collected from 

multiple sources can be viewed on the 

Point Blue Whale Database. This 

information will be considered in 

combination with our assessment of the 

impacts of harassment takes later in the 

section. 

Sei Whale (Eastern North Pacific Stock) 

For sei whales (Eastern North Pacific 

stock) PBR is currently set at 0.75 and 

the total annual M/SI is 0 yielding a 

residual PBR of 0.75. The M/SI value 

includes incidental fishery interaction 

records of 0, and records of vessel 

collisions of 0. The proposed 

authorization of 0.2 mortalities annually 

represents 26 percent of residual PBR. 

Because this value is not close to, at, or 

exceeding residual PBR, it means that 

the proposed M/SI is not expected to 

result in more than a negligible impact 

on this stock. This information will be 

considered in combination with our 

assessment of the impacts of harassment 

takes later in the section. 

Sei Whale (Hawaiian Stock) 

For sei whales (Hawaiian stock) PBR 

is currently set at 0.2 and the total 

annual M/SI is 0.2 yielding a residual 

PBR of 0. The M/SI value includes 

incidental fishery interaction records of 

0.2, and records of vessel collisions of 

0. The proposed authorization of 0.2 

mortalities is above residual PBR (by 

0.2). We note, however, that this stock 

occurs within the Hawaiian Islands EEZ 

and in adjacent high seas waters; 

however, because data on abundance, 

distribution, and human-caused impacts 

are largely lacking for high seas waters, 

the status of this stock is evaluated 

based on data from U.S. EEZ waters 

(NMFS 2005). If the higher number of 

whales in the high seas (which are 

uncounted) are considered in 

combination with the lower likely 

numbers of mortality in the high seas 

(since the only known mortality is from 


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fishery interaction, which occurs 

predominantly in the U.S. EEZ), then 

the current PBR is likely overly 

conservative in the context of M/SI 

takes that could occur in or outside of 

the U.S. EEZ. Additionally, as noted in 

the discussion above, PBR is a 

conservative metric that is not intended 

to serve as an absolute cap on 

authorized mortality, one mortality is 

the smallest amount that could possibly 

occur in a five-year period, and when 

this fractional addition is considered in 

the context of barely exceeding residual 

PBR, any impacts on the stock are not 

expected to be more than negligible. 

This information will be considered in 

combination with our assessment of the 

impacts of harassment takes later in the 

section. 

Bryde’s Whale (Eastern Tropical Pacific 

Stock) 

For Bryde’s whales (Eastern Tropical 

Pacific stock) PBR is currently 

undetermined and the total annual 

M/SI is 0.2. Therefore, residual PBR is 

unknown. The M/SI value includes 

incidental fishery interaction records 

which are unknown, and records of 

vessel collisions are 0.2. The total 

human-caused mortality is very low and 

the Navy’s activities would add a 

fractional amount. Given the fact that 

this stock contains animals that reside 

both within and outside the U.S. EEZ (a 

very large range) and there known M/SI 

of only 0.2, it is unlikely that the 

addition of 0.2 annual mortality would 

result in more than a negligible impact 

on this stock. This information will be 

considered in combination with our 

assessment of the impacts of harassment 

takes later in the section. 

Minke Whale (Hawaiian Stock) 

For minke whales (Hawaiian stock) 

PBR is currently undetermined and the 

total annual M/SI is unknown; 

therefore, residual PBR is unknown. The 

M/SI value includes incidental fishery 

interaction records of 0, and records of 

vessel collisions of 0. Given the fact that 

this stock contains animals that reside 

both within and outside the U.S. EEZ (a 

very large range) and there is no known 

M/SI, it is unlikely that the addition of 

0.2 annual mortality would result in 

more than a negligible impact on this 

stock. This information will be 

considered in combination with our 

assessment of the impacts of harassment 

takes later in the section. 

Group and Species-Specific Analysis 

In the discussions below, the 

‘‘acoustic analysis’’ refers to the Navy’s 

analysis, which includes the use of 

several models and other applicable 

calculations as described in the 

Estimated Take of Marine Mammals 

section. The quantitative analysis 

process used for the HSTT DEIS/OEIS 

and the Navy’s rulemaking/LOA 

application to estimate potential 

exposures to marine mammals resulting 

from acoustic and explosive stressors is 

detailed in the technical report titled 

Quantifying Acoustic Impacts on 

Marine Mammals and Sea Turtles: 

Methods and Analytical Approach for 

Phase III Training and Testing report 

(U.S. Department of the Navy, 2017b). 

The Navy Acoustic Effects Model 

estimates acoustic and explosive effects 

without taking mitigation into account. 

Therefore, the model overestimates 

predicted impacts on marine mammals 

within mitigation zones. To account for 

mitigation, as well as avoidance, for 

marine mammals, the Navy developed a 

methodology to conservatively quantify 

the likely degree that mitigation and 

avoidance will reduce model-estimated 

PTS to TTS for exposures to sonar and 

other transducers, and reduce modelestimated mortality and injury for 

exposures to explosives. 

The amount and type of incidental 

take of marine mammals anticipated to 

occur from exposures to sonar and other 

active acoustic sources and explosions 

during the five-year training and testing 

period are shown in Tables 41 and 42. 

The vast majority of predicted 

exposures (greater than 99 percent) are 

expected to be Level B harassment (noninjurious TTS and behavioral reactions) 

from acoustic and explosive sources 

during training and testing activities at 

relatively low received levels. 

The analysis below may in some cases 

(e.g., mysticetes, porpoises, pinnipeds) 

address species collectively if they 

occupy the same functional hearing 

group (i.e., low, mid, and highfrequency cetaceans and pinnipeds in 

water), have similar hearing capabilities, 

and/or are known to generally 

behaviorally respond similarly to 

acoustic stressors. Animals belonging to 

each stock within a species would have 

the same hearing capabilities and 

behaviorally respond in the same 

manner as animals in other stocks 

within the species. Therefore, our 

analysis below also considers the effects 

of Navy’s activities on each affected 

stock. Where there are meaningful 

differences between species or stocks in 

anticipated individual responses to 

activities, impact of expected take on 

the population due to differences in 

population status, or impacts on habitat, 

they will either be described within the 

section or the species will be included 

as a separate sub-section. 

Mysticetes 

In Table 69 and Table 70 below, for 

mysticetes, we indicate the total annual 

mortality, Level A and Level B 

harassment, and a number indicating 

the instances of total take as a 

percentage of abundance. Overall, takes 

from Level A harassment (PTS and 

Tissue Damage) account for less than 

one percent of all total takes. 

BILLING CODE 3510–22–P 


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Table 69. Annual takes of Level B and Level A harassment, mortality for mysticetes in the 

HRC of the HSTT study area and number indicating the instances of total take as a 

percentage of stock abundance. 

level B Harassment 

level A 

Total Takes Abundance 

Instance of total take as 

Harassment percent of abundance 

Total take 

Species Mortality TOTAL Takes Total Navy Within as EEZ take as 

TIS (may TAKES percentage percentage Stock Behavioral also include PTS Tissue (entire (within Abundance Navy EEZ of total ofEEZ 

Navy EEZ Disturbance Damage NAVY in and out Abundance 

location (HRC) disturbance) Study EEZ) EEZ (HRC) HRC Navy abundance 

Area) abundance (HRC) 

(HRC) 

Blue whale 

Central North 15 33 0 0 0 48 40 43 33 112 121 

Pacific (HRC) 

Bryde's whale 40 107 0 0 0 147 123 108 89 136 138 

Hawaiian (HRC) 

Fin whale 

Hawaiian 21 28 0 0 0 49 41 52 40 94 103 

(HRC) 

Humpback whale 

Central North 

Pacific 2838 6290 5 0 0 9133 7389 5078 4595 180 161 

(HRC) 

Minke whale 

Hawaiian 1233 3697 2 0 0 4932 4030 3652 2835 135 142 

(HRC) 

Sei whale 

Hawaiian 47 121 0 0 0 168 135 138 107 122 126 

(HRC) 

Note: For the Hl take estimates. compare pred1cted takes to abundance estJmates generated !rom the same underlymg denstty estimates, both 

in and outside ofthe EEL Because the portion of the action area inside the U.S. EEZ generally concomitant with the study area 

used to generate the abundance estimates in the SARs, and the abundance predicted by the same underlying density estimates is the preferred 

abundance to there is no need to separately compare the take to the SARs abundance estimate. 
Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 29995 

BILLING CODE 3510–22–C 

Of these species, blue whale, fin 

whale, sei whale, humpback whale (CA/ 

OR/WA stock) and gray whale (Western 

North Pacific stock) are listed as 

endangered under the ESA and depleted 

under the MMPA. NMFS is currently 

engaged in an internal Section 7 

consultation under the ESA and the 

outcome of that consultation will 

further inform our final decision. 

Of the total instances of all of the 

different types of takes, the numbers 

indicating the instances of total take as 

a percentage of abundance for 

mysticetes ranges from 94 to 180 

percent for HRC stocks (blue, Bryde’s, 

fin, humpback minke and sei whales), 

suggesting that most individuals are 

taken in an average of 1 to 2 days per 

year (Table 69). For SOCAL stocks (blue, 

Bryde’s, fin, humpback, minke, sei, and 

gray whales), the percentages as 

compared to the abundances across the 

U.S. EEZ stock range (Predicted in the 

SAR) are between 4 and 146, suggesting 

that across these wide-ranging stocks 

individuals are taken on average on 

between 0 and 2 days per year (Table 

70). Alternately when compared to the 

abundance estimates within the Navy’s 

SOCAL action area, based on static 

density estimates, the percentages range 

from 0 to 3,154, suggesting that if any 

of these exposed individuals remained 

in the action area the whole year, they 

might be taken on average on 32 days 

in a year. Although we generally do not 

expect individuals to remain in the 

action area for the whole year (or to 

accrue take over this many days), these 

numbers do suggest that individuals 

residing in the action area for some 

amount of time could accrue take on 

more than the average one or two days 

per year. Effects are such that these 

averages allow that perhaps a smaller 

subset is taken with a slightly higher 

average and larger variability of highs 

and lows, but still with no reason to 

think that any individuals would be 

taken every day for weeks or months out 

of the year, much less on sequential 

days. These behavioral takes are 

expected to be of a milder to potentially 

moderate intensity and are not likely to 

occur over sequential days, which 

suggests that the overall scale of impacts 

for any individual would be relatively 

low and unlikely to result in fitness 

effects that would impact reproductive 

success or survival. 

Most Level B harassments to 

mysticetes from hull-mounted sonar 

(MF1) in the HSTT Study Area would 

result from received levels between 154 

and 172 dB SPL (62 percent). As 

mentioned earlier in this section, we 

anticipate more severe effects from takes 

when animals are exposed to higher 

received levels. Comparatively minor to 

potentially moderate behavioral 

reactions are unlikely to cause long-term 

consequences for individual animals or 

populations, and even if some smaller 

subset of the takes are in the form of a 

longer (several hours or a day) and more 

moderate response, because they are not 

expected to be repeated over sequential 

multiple days, impacts to individual 

fitness are not anticipated. Also, as 

noted in the Potential Effects section, 

while there are multiple examples from 

behavioral response studies of 

odontocetes ceasing their feeding dives 

when exposed to sonar pulses at certain 

levels, but alternately, blue whales were 


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less likely to show a visible response to 

sonar exposures at certain levels when 

feeding then they have been observed 

responding to when traveling. 

Research and observations show that 

if mysticetes are exposed to sonar or 

other active acoustic sources they may 

react in a number of ways depending on 

the characteristics of the sound source, 

their experience with the sound source, 

and whether they are migrating or on 

seasonal grounds (i.e., breeding or 

feeding). Behavioral reactions may 

include alerting, breaking off feeding 

dives and surfacing, diving or 

swimming away, or no response at all 

(Richardson, 1995; Nowacek, 2007; 

Southall et al., 2007; Finneran and 

Jenkins, 2012). Overall, mysticetes have 

been observed to be more reactive to 

acoustic disturbance when a noise 

sources is located directly on their 

migration route. Mysticetes disturbed 

while migrating could pause their 

migration or route around the 

disturbance. Although they may pause 

temporarily, they will resume migration 

shortly after. Animals disturbed while 

engaged in other activities such as 

feeding or reproductive behaviors may 

be more likely to ignore or tolerate the 

disturbance and continue their natural 

behavior patterns. Therefore, most 

behavioral takes of mysticetes are likely 

to be short-term and low to moderate 

severity. 

While MTEs may have a longer 

duration, they are not concentrated in 

small geographic areas over that time 

period. MTES use hundreds of square 

miles of ocean space during the course 

of the event. For example, Goldbogen et 

al. (2013) indicated some horizontal 

displacement of deep foraging blue 

whales in response to simulated MFA 

sonar. Given these animals’ mobility 

and large ranges, we would expect these 

individuals to temporarily select 

alternative foraging sites nearby until 

the exposure levels in their initially 

selected foraging area have decreased. 

Therefore, temporary displacement from 

initially selected foraging habitat is not 

expected to impact the fitness of any 

individual animals because we would 

expect suitable foraging to be available 

in close proximity. 

Richardson et al. (1995) noted that 

avoidance (temporary displacement of 

an individual from an area) reactions are 

the most obvious manifestations of 

disturbance in marine mammals. 

Avoidance is qualitatively different 

from the startle or flight response, but 

also differs in the magnitude of the 

response (i.e., directed movement, rate 

of travel, etc.). Oftentimes avoidance is 

temporary, and animals return to the 

area once the noise has ceased. Some 

mysticetes may avoid larger activities 

such as a MTE as it moves through an 

area, although these activities generally 

do not use the same training locations 

day-after-day during multi-day 

activities. Therefore, displaced animals 

could return quickly after the MTE 

finishes. Due to the limited number and 

broad geographic scope of MTEs, it is 

unlikely that most mysticetes would 

encounter a major training exercise 

multiple times per year when transiting 

through the area. In the ocean, the use 

of sonar and other active acoustic 

sources is transient and is unlikely to 

expose individuals repeatedly over a 

short period except around homeports 

and fixed instrumented ranges. 

However, the more impactful training 

exercises that result in higher numbers 

or more severe forms of take do not 

occur around homeports. While training 

exercises may be concentrated in 

instrumented ranges, they are large 

areas, and in most cases the animals are 

not limited to those areas and the 

numbers in the analysis above do not 

suggest that any individual mysticetes 

are being exposed to levels above the 

Level B harassment threshold within 

more than than maybe 20–30 days at 

most over the course of a year. 

The implementation of mitigation and 

the sightability of mysticetes (due to 

their large size) and therefore higher 

likelihood that shutdown and other 

mitigation measures will be effective for 

these species and reduces the potential 

for a more significant behavioral 

reaction or a threshold shift to occur 

(which would be more likely within the 

shutdown zone, were the mitigation not 

implemented). As noted previously, 

when an animal incurs a threshold shift, 

it occurs in the frequency from that of 

the source up to one octave above—this 

means that threshold shift caused by 

Navy sonar sources will typically occur 

in the range of 2–20 kHz, and if 

resulting from hull-mounted sonar, will 

be in the range of 3.5–7 kHz. The 

majority of mysticete vocalizations 

occur in frequencies below 1 kHz, 

which means that TTS incurred by 

mysticetes will not interfere with 

conspecific communication. When we 

look in ocean areas where the Navy has 

been intensively training and testing 

with sonar and other active acoustic 

sources for decades, there is no data 

suggesting any long-term consequences 

to mysticetes from exposure to sonar 

and other active acoustic sources. 

The Navy will implement mitigation 

areas that will avoid or reduce impacts 

to mysticetes and where BIAs for large 

whales have been identified in the 

SOCAL portion of the HSTT Study 

Area. The Navy will implement the San 

Diego Arc Mitigation Area from June 1 

through October 31 to protect blue 

whales. The San Diego Arc overlaps the 

San Diego Blue Whale Feeding Area 

(BIA) (see also the HSTT DEIS/OEIS 

Section K.4 (BIAs within the SOCAL 

Portion of the HSTT Study Area for blue 

whale feeding areas)). In the San Diego 

Arc Mitigation Area the Navy will not 

exceed 200 hrs of MFAS sensor MF1 use 

((with the exception of active sonar 

maintenance and systems checks) 

between June 1 and October 31 

annually. Additionally, in the San Diego 

Arc Mitigation Area, the Navy will not 

use explosives during large-caliber 

gunnery, torpedo, bombing, and missile 

(including 2.75 in rockets) activities 

during training or testing. 

In addition, the Navy will implement 

the Santa Barbara Island Mitigation Area 

year-round for the protection of blue, 

fin, and gray whales (and other marine 

mammals) within that portion of the 

Channel Islands NMS. The Santa 

Barbara Island Mitigation Area will 

partially protect the identified 

important feeding area, San Nicolas 

Island for blue whales. The Navy will 

restrict the use of MFAS sensor MF1 

and explosives used in gunnery (all 

calibers), torpedo, bombing, and missile 

exercises (including 2.75 in rockets) 

during unit-level training and MTEs. 

The Navy will implement mitigation 

areas that will avoid or reduce impacts 

to mysticetes and where BIAs for large 

whales have been identified in the HRC 

portion of the HSTT Study Area as 

described below. 

In the 4-Islands Region Mitigation 

Area, the Navy will not use MFAS 

sensor MF1 during training or testing 

activities from November 15 through 

April 15. Since 2009, the Navy has 

adhered to a Humpback Whale 

Cautionary Area as a mitigation area 

within the Hawaiian Islands Humpback 

Whale NMS an area identified as having 

one of the highest concentrations of 

humpback whales, with calves, during 

the critical winter months. As added 

protection, the Navy proposes to expand 

the size and extend the season of the 

current Humpback Whale Cautionary 

Area, renaming this area the 4-Islands 

Region Mitigation Area to reflect the 

benefits afforded to multiple species. 

The season is currently between 

December 15 and April 15; the Navy 

proposes to extend it from November 15 

through April 15 because the peak 

humpback whale season has expanded. 

The size of the 4-Islands Region 

Mitigation Area would expand to 

include an area north of Maui and 

Molokai and overlaps an area identified 

as a BIA for the critically endangered 

Main Hawaiian Islands insular false 


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killer whales (Baird et al., 2015; Van 

Parijs, 2015) (see Figure 5.4–3, in 

Chapter 5 Mitigation Areas for Marine 

Mammals in the Hawaii Range Complex 

of the HSTT DEIS/OEIS). This proposed 

measure to include the additional area 

north of Maui and Molokai for this 4- 

Islands Region Mitigation Area further 

reduces impacts to humpback whales 

(and false killer whales). 

Within the 4-Islands Region 

Mitigation Area is the Hawaiian Island 

Humpback Whale Reproduction Area 

BIA (4-Islands Region and Penguin 

Bank). The use of sonar and other 

transducers primarily occur farther 

offshore than the designated boundaries 

of the Hawaiian Islands Humpback 

Whale Reproduction Area BIA. 

Explosive events are typically 

conducted in areas that are designated 

for explosive use, which are areas 

outside of the Hawaiian Islands 

Humpback Whale Reproduction Area 

BIA. 

The restrictions on MFAS sensor MF1 

in this area and the fact that the Navy 

does not plan to use any explosives in 

this area means that the number of takes 

of humpback whales will be lessened, as 

will their potential severity, in that the 

Navy is avoiding exposures in an area 

and time where they would be more 

likely to interfere with cow/calf 

communication or potentially 

heightened impacts on sensitive or 

naı ̈ve individuals (calves). 

The Navy is also proposing an 

additional mitigation area, the Hawaii 

Island Mitigation Area. The Hawaii 

Island Mitigation Area would be 

established where year-round, where 

the Navy will not use more than 300 hrs 

of MFAS sensory MF1 and will not 

exceed 20 hrs of MFAS senory MF4 

year-round. Also within the Hawaii 

Island Mitigation Area, the Navy will 

not use any explosives (e.g., surface-tosurface or air-to-surface missile and 

gunnery events, BOMBEX, and mine 

neutralization) during testing and 

training year-round. Of note here, this 

measure would provide additional 

protection in this important 

reproductive area for humpback whales, 

reducing impacts in an area and time 

where they would likely be more severe 

if incurred. Separately (and addressed 

more later), these protected areas also 

reduce impacts for identified 

biologically important areas for 

endangered Main Hawaiian Islands 

insular false killer whales, two species 

of beaked whales (Cuvier and 

Blainville’s), dwarf sperm whale, pygmy 

killer whale, melon-headed whale, 

short-finned pilot whale, and dolphin 

species (Baird et al., 2015; Van Parijs, 

2015). 

The 4-Islands Region Mitigation Area 

and the Hawaii Island Mitigation Area 

both also overlap with portions of the 

Hawaiian Islands Humpback Whale 

NMS. It is also of note that Navy 

training and testing in the Hawaiian 

Islands Humpback Whale NMS will 

follow the procedural mitigation 

measure that humpbacks are not 

approached within 100 yds and aircraft 

operate above 1,000 ft, which further 

lessens the likelihood of ship strike and 

behavioral disturbance resulting from 

aircraft, respectively. 

The Navy will continue to issue an 

annual humpback whale awareness 

notification message to remind ships 

and aircraft to be extra vigilant during 

times of high densities of humpback 

whales while in transit and to maintain 

certain distances from animals during 

the operation of ships and aircraft. 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from Navy’s activities 

are not expected to adversely affect the 

mysticetes stocks through effects on 

annual rates of recruitment or survival. 

• As described in the ‘‘Serious Injury 

or Mortality’’ section above, between 

zero and two serious injuries or 

mortalities over the five-year period 

could occur for large whales (see Tables 

67) depending on the species. 

Æ Using PBR as a consideration in 

assessing these possible mortalities, the 

possible mortality for fin whale (CA/ 

OR/WA), gray whale (Eastern North 

Pacific stock), humpback whales (CA/ 

OR/WA and Central Pacific stocks), 

Bryde’s whale (Hawaiian stock), and 

Minke whale (CA/OR/WA stock) is 

below the insignificance threshold of 10 

percent of residual PBR. 

Æ The possible total mortality for 

sperm whale (CA/OR/WA stock), blue 

whale (Eastern North Pacific Stock) and 

sei whales (Eastern North Pacific stock) 

is below residual PBR. 

Æ The possible total mortality for sei 

whale (Hawaiian stock) is equal to PBR, 

which places it slightly above residual 

PBR because of the other known human 

mortality. PBR is a conservative metric 

that is not intended to serve as an 

absolute cap on authorized mortality. 

One mortality is the smallest amount 

that could possibly occur in a five-year 

period, and when this fractional 

addition is considered in the context of 

barely exceeding residual PBR, any 

impacts on the stock are not expected to 

be more than negligible. 

Æ While residual PBR is not known 

for minke whales (Hawaiian stock) and 

Bryde’s whales (Eastern Tropical Pacific 

stock), very little other human-caused 

mortality is known for either stock, and 

the Navy’s activities would add a 

fractional amount to these wide-ranging 

stocks. 

• As described above, any PTS that 

may occur is expected to be of a small 

degree, and any TTS of a relatively 

small degree because of the 

unlikelihood that animals would be 

close enough for a long enough period 

of time to incur more severe PTS (from 

sonar) and the anticipated effectiveness 

of mitigation in preventing very close 

exposures for explosives, as discussed 

above. Further, as noted above, any 

threshold shift incurred from sonar 

would be in the frequency range of 2– 

20 kHz, which is above the frequency of 

the majority of mysticete vocalizations, 

and therefore would not be expected to 

interfere with conspecific 

communication. 

• While the majority of harassment 

takes are caused by exposure during 

ASW activities, the impacts from these 

exposures are not expected to be 

significant and are generally expected to 

be short-term because (and as discussed 

above): 

Æ ASW activities typically involve 

fast-moving assets (relative to marine 

mammal swim speeds) and individuals 

are not expected to be exposed either for 

long periods within a day or over many 

sequential days. 

Æ The majority of the harassment 

takes result from hull-mounted sonar 

during MTEs. When distance cut offs for 

mysticetes are applied, this means that 

all of the takes from hull-mounted sonar 

(MF1) result from above exposure 154 

dB. However, the majority (e.g., 62 

percent) of the takes results from 

exposures below 172 dB. The majority 

of the takes are not from higher level 

exposures from which more severe 

responses would be expected. 

Æ As described in more detail above, 

the scale of effects are such that most 

individuals of the HRC stocks are taken 

in an average of 1 or 2 days per year and 

individuals of the SOCAL stocks are 

taken an average of a few days per year, 

with the likelihood that some smaller 

subset might be taken in notably more 

than a few days per year, but likely 

something less than 6–32 days per year, 

but, given this number of takes spread 

across a year and the nature of the 

Navy’s activities, these takes are not 

expected to typically occur over 

sequential days. 

• The Navy is implementing 

mitigation areas that specifically reduce 

or avoid impacts to humpback whales in 

their important Hawaii calving area and 

blue whales in their California feeding 

areas, and further reduce impacts over 

all to mysticetes in several other areas, 

all of which is expected to reduce the 


sradovich on DSK3GMQ082PROD with PROPOSALS2

EP26JN18.101</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Table 71. Annual takes of Level B and Level A harassment, mortality for sperm whales in the HRC 

the HSTT study area and number indicating the instances of total take as a percentage of stock abu

Instances of indicated types of incidental take 

(not all takes represent separate individuals, 

especially for disturbance) 

level B Harassment level A Total Takes Abundance Instance of total tak

Harassment percent of abundan

Total take 

Species Mortality TOTAL Takes Total Navy Within as EEZ take 

Stock TIS (may TAKES percentage percent

Navy EEZ Behavioral also include PTS Tissue (entire (within Abundance Navy EEZ of total EEZ 

location Disturbance disturbance) Damage Study NAVY in and out Abundance Navy abundan

(HRC) Area) EEZ) EEZ (HRC) HRC (gray) abundance (HRC) 

(HRC) 

Sperm 

whale 

Hawaiian 2466 30 0 0 0 1930 1317 1656 1317 151 14

(HRC) 

Note: For the III take estimates, we compare predicted takes to abundance estimates generated from the same underlying density estimates, both in and out

EEZ. Because the pmiion of the action area inside the LS. EEL is generally concomitant with the study area used to generate the abundance e

in the SARs, and the abundance predicted by the same underlying density estimates is the prefen·ed abundance to use, there no need to separately compar

the take to the SARs abundance estimate. 
BILLING CODE 3510–22–C 

All takes annually for sperm whales 

OR/WA and Hawaii stocks) and 

endangered under the ESA (both CA/ 

above). Sperm whales are listed as 

behavioral or TTS (Tables 71 and 72 

are from Level B harassment either 

further inform our final decision. 

outcome of that consultation will 

7 consultation under the ESA and the 

currently engaged in an internal Section 

depleted under the MMPA. NMFS is 

Most Level B harassments to sperm 

whales and from hull-mounted sonar 

responses (

expected to be in the form of milder 

the majority of Level B takes are 

and 166 dB SPL (85 percent). Therefore, 

result from received levels between 154 

(MF1) in the HSTT Study Area would 

i.e., lower-level exposures 

that still rise to the level of take, but 


EP26JN18.102</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Instances of indicated types of incidental take 

(not all takes represent separate individuals, especially 

for disturbance) 

level B Harassment level A Harassment Total Abundance 

Takes 

TOTAL NAVY 

TTS (may abundance NM

TAKES 

Species Stock Behavioral also include PTS Tissue Mortality (entire in Action SAR

Disturbance Damage Abund

disturbance) Study Area 2 

Area) SOCAL 1 

Sperm CA/OR/WA 2437 56 0 0 0 2493 273 199

whale 

Note: For the SOCAL take estimates, because of the manner in which the Navy action area overlaps the ranges of many MMPA stocks (i.e., a sto

Washington state and beyond and abundance may only be predicted within the U.S. EEZ, while the Navy action area is limited to Southern Califo

extends beyond the U.S. EEZ), we compare predicted takes to both the abundance estimates for the action area, as well as the SARs. 
30000 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

would likely be less severe in the range 

of responses that qualify as take). As 

mentioned earlier in this section, we 

anticipate more severe effects from takes 

when animals are exposed to higher 

received levels. Occasional mild to 

moderate behavioral reactions are 

unlikely to cause long-term 

consequences for individual animals or 

populations, and even if some smaller 

subset of the takes are in the form of a 

longer (several hours or a day) and more 

moderate response, because they are not 

expected to be repeated over sequential 

multiple days, impacts to individual 

fitness are not anticipated. 

For the total instances of all of the 

different types of takes, the numbers 

indicating the instances of total take as 

a percentage of abundance for sperm 

whales are generally between 125 and 

151, with 913 for the CA/OR/WA stock 

of sperm whales specifically when 

compared against the Navy’s action area 

abundance. Based on the percentages 

above, most individuals are taken in an 

average of 1–2 days per year based on 

the overall abundance of these farranging stocks, while some sperm whale 

individuals that might remain in the 

Navy’s SOCAL action area for extended 

periods may be taken on more like an 

average of nine days in a year. These 

averages allow that perhaps a smaller 

subset is taken with a slightly higher 

average and larger variability of highs 

and lows, but still with no reason to 

think that any individuals would be 

taken every day for weeks or months out 

of the year, much less on sequential 

days. The majority of these behavioral 

takes are expected to be of a milder 

intensity (compared to those that occur 

at higher levels) and are not likely to 

occur over sequential days, which 

suggests that the overall scale of impacts 

for any individual would be relatively 

low and unlikely to result in fitness 

effects that would impact reproductive 

success or survival. 

Sperm whales have shown resilience 

to acoustic and human disturbance, 

although they may react to sound 

sources and activities within a few 

kilometers. Sperm whales that are 

exposed to activities that involve the 

use of sonar and other active acoustic 

sources may alert, ignore the stimulus, 

avoid the area by swimming away or 

diving, or display aggressive behavior 

(Richardson, 1995; Nowacek, 2007; 

Southall et al., 2007; Finneran and 

Jenkins, 2012). Some (but not all) sperm 

whale vocalizations might overlap with 

the MFAS/HFAS TTS frequency range, 

which could temporarily decrease an 

animal’s sensitivity to the calls of 

conspecifics or returning echolocation 

signals. However, as noted previously, 

NMFS does not anticipate TTS of a long 

duration or severe degree to occur as a 

result of exposure to MFAS/HFAS. 

Recovery from a threshold shift (TTS) 

can take a few minutes to a few days, 

depending on the exposure duration, 

sound exposure level, and the 

magnitude of the initial shift, with 

larger threshold shifts and longer 

exposure durations requiring longer 

recovery times (Finneran et al., 2005; 

Mooney et al., 2009a; Mooney et al., 

2009b; Finneran and Schlundt, 2010). 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from Navy’s activities 

are not expected to adversely affect 

sperm whales through effects on annual 

rates of recruitment or survival: 

• As described in the ‘‘Serious Injury 

or Mortality’’ section (Table 67), one or 

two mortalities over five years is 

proposed for authorization for sperm 

whales (for CA/OR/WA and Hawaiian 

stocks, respectively). 

Æ The proposed serious injury or 

mortality for the sperm whale (Hawaiian 

stock) does fall below the insignificance 

threshold and, therefore, we consider 

the addition an insignificant 

incremental increase to human-caused 

mortality. 

Æ The possible total serious injury or 

total mortality for sperm whale (CA/OR/ 

WA stock) falls below residual PBR. 

NOAA is currently implementing 

marine mammal take reduction 

measures as identified in the Pacific 

Offshore Cetacean Take Reduction Plan 

that addresses incidental serious injury 

and mortality of sperm whales, and 

other whales in the CA/OR swordfish 

drift gillnet fishery. The total 

anticipated human-caused mortality is 

not expected to exceed PBR for both 

stocks. 

• No PTS or injury from acoustic or 

explosive stressors is proposed for 

authorization or anticipated to occur for 

sperm whales. 

• While the majority of takes are 

caused by exposure during ASW 

activities, the impacts from these 

exposures are not expected to have 

either significant or long-term effects 

because (and as discussed above): 

Æ ASW activities typically involve 

fast-moving assets (relative to marine 

mammal swim speeds) and individuals 

are not expected to be exposed either for 

long periods within a day or over many 

sequential days. 

Æ As discussed, the majority of the 

harassment takes result from hullmounted sonar during MTEs. When 

distance cutoffs are applied for 

odontocetes, this means that all of the 

takes from hull-mounted sonar (MF1) 

result from above exposure 154 dB. 

However, the majority (e.g., 85 percent) 

of the takes results from exposures 

below 166 dB. The majority of the takes 

are not from higher level exposures from 

which more severe responses would be 

expected. 

• As described in more detail above 

(Table 71 and 72), the scale of the effects 

are such that for sperm whales, most 

individuals are take in an average of 1– 

2 days per year, while some subset of 

individuals that might remain in the 

Navy’s SOCAL action area for extended 

periods could be taken on an average of 

9 days per year. As described above, 

given this number of takes spread across 

a year and the nature of the Navy’s 

activities, these takes are not expected 

to typically occur over sequential days. 

• The HSTT activities are not 

expected to occur in an area/time of 

specific importance for reproductive, 

feeding, or other known critical 

behaviors for sperm whales and there is 

no designated critical habitat in the 

HSTT Study Area. 

Consequently, the HSTT activities are 

not expected to adversely impact rates 

of recruitment or survival of any of the 

analyzed stocks of sperm whales (Table 

73 above in this section). 

Kogia spp. 

In Table 73 and 74 below, for Kogia 

spp. we indicate the total annual 

mortality, Level A and Level B 

harassment, and a number indicating 

the instances of total take as a 

percentage of abundance. Overall, takes 

from Level A harassment (PTS and 

Tissue Damage) account for less than 

one percent of all total takes. 

BILLING CODE 3510–22–P 


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EP26JN18.103</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Table 73. Annual takes of Level B and Level A harassment, mortality for Kogia 

of the HSTT study area and number indicating the instances of total take as a p

abundance. 

Instances of indicated types of incidental take 

(not all takes represent separate individuals, 

especially for disturbance) 

level B Harassment level A Total Takes Abundance 

Harassment 

Species TOTAL Takes Total Navy Within 

Stock TTS (may Mortality TAKES 

Behavioral Tissue (within Abundance Navy EE

Navy EEZ Disturbance also include PTS Damage (entire NAVY in and out Abunda

location disturbance) Study 

(HRC) Area) EEZ) EEZ (HRC) HRC 

Dwarf 

sperm 

whale 5870 14550 64 0 0 20484 15310 8218 6379 

Hawaiian 

(HRC) 

Pygmy 

sperm 

whale 2329 5822 27 0 0 8178 6098 3349 2600 

Hawaiian 

(HRC) 

Note: For the HI take estimates, compare predicted takes to abundance estimates generated from the same underlying dens

the C.S. EEZ. Because the portion of the Navy"s action area inside the U.S. EEZ is generally concomitant with the study area 

estimates in the SARs, and the abundance predicted by the same underlying density estimates is the prelim-ed abundance to use

compare the take to the SARs abundance estimate. 
BILLING CODE 3510–22–C 

Nearly all takes annually for Kogia 

listed. 

anticipated. These species are not ESANo serious injury, or mortalities are 

percent PTS) (Tables 73 and 74 above). 

either behavioral or TTS (less than 1 

species are from Level B harassment 

Most Level B harassments to Kogia 

spp. from hull-mounted sonar (MF1) in 

mentioned earlier in this section, we 

compared to higher level exposures). As 

to be in the form of milder responses (as 

majority of Level B takes are expected 

SPL (85 percent). Therefore, the 

received levels between 154 and 166 dB 

the HSTT Study Area would result from received levels. 

when animals are exposed to higher 

anticipate more severe effects from takes 

For the total instances of all of the 

a percentage of abundance for 

indicating the instances of total take as 

different types of takes, the numbers 

Kogia 

249, with 1,211 for the CA/OR/WA 

whales are generally between 223 and 


EP26JN18.104</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Table 74. Annual takes of Level Band Level A harassment, mortality for Kogia species 

HSTT study area and number indicating the instances of total take as a percentage of st

Instances of indicated types of incidental take 

(not all takes represent separate individuals, 

especially for disturbance) 

level B Harassment level A Harassment Total Abundance 

Takes 

TOTAL NAVY 

TTS (may abundance NMF

TAKES 

Species Stock Behavioral also include PTS Tissue Mortality (entire in Action SAR

Disturbance Damage Abund

Disturbance) Study Area 2 

Area) SOCAL 1 

Kogia CA/OR/WA 2779 6353 38 0 0 9170 757 411

whales 

Note: For the SOCAL take estimates, because of the manner in which the Navy action area overlaps the ranges of many MMPA stocks (i.e.

Washington state and beyond and abundance may only be predicted within the U.S. EEZ, while the Navy action area is limited to Southern 

but extends beyond the U.S. EEZ), we compare predicted takes to both the abundance estimates for the action area, as well as the SARs. 
Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 30003 

stock of Kogia, specifically when 

compared against the Navy’s action area 

abundance. Based on the percentages 

above, most individuals are taken in an 

average of 3 days in a year, while some 

Kogia individuals that might remain in 

the SOCAL action area may be taken an 

average of 12 days in a year. These 

averages allow that perhaps a smaller 

subset is taken with a slightly higher 

average and larger variability of highs 

and lows, but still with no reason to 

think that any individuals would be 

taken every day for weeks or months out 

of the year, much less on sequential 

days. The majority of these behavioral 

takes are expected to be of a milder 

intensity (compared to those that occur 

at higher levels) and nor are they likely 

to occur over sequential days, which 

suggests that the overall scale of impacts 

for any individual would be relatively 

low and unlikely to result in fitness 

effects that would impact reproductive 

success or survival. 

The quantitative analysis predicts 

small numbers of PTS per year from 

sonar and other transducers (during 

training and testing activities). However, 

Kogia whales would likely avoid sound 

levels that could cause higher levels of 

TTS (greater than 20 dB) or PTS. TTS 

and PTS thresholds for high-frequency 

cetaceans, including Kogia whales, are 

lower than for all other marine 

mammals, which leads to a higher 

number of estimated impacts relative to 

the number of animals exposed to the 

sound as compared to other hearing 

groups (e.g., mid-frequency cetaceans). 

Impacts to dwarf and pygmy sperm 

whale stocks (small and resident 

populations BIAs) will be reduced 

through the Hawaii Island Mitigation 

Area that limits the use of midfrequency active anti-submarine warfare 

sensor bins MF1 and MF4 and where 

the Navy will not use explosives during 

testing and training (e.g., surface-tosurface or air-to-surface missile and 

gunnery events, BOMBEX, and mine 

neutralization). 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from Navy’s activities 

are not expected to adversely affect 

Kogia spp. through effects on annual 

rates of recruitment or survival. 

• No serious injuries or mortalities 

are proposed for authorization or 

anticipated to occur for Kogia spp. 

• While the majority of takes are 

caused by exposure during ASW 

activities, the impacts from these 

exposures are not expected to have 

either significant or long-term effects 

because (and as discussed above): 

Æ ASW activities typically involve 

fast-moving assets (relative to marine 

mammal swim speeds) and individuals 

are not expected to be exposed either for 

long periods within a day or over many 

sequential days. 

Æ As discussed, the majority of the 

harassment takes result from hullmounted sonar during MTEs. When 

distance cutoffs are applied for 

odontocetes, this means that all of the 

takes from hull-mounted sonar (MF1) 

result from above exposure 154 dB. 

However, the majority (e.g., 85 percent) 

of the takes results from exposures 

below 166 dB. The majority of the takes 

have a relatively lower likelihood in 

have severe impacts. 

• As described in more detail above 

(Tables 73 and 74), the scale of the 

effects are such that pygmy and dwarf 

sperm whale are taken an average of 2– 

3 days per year, while some subset of 

individuals that might remain in the 

SOCAL action area for extended periods 

could be taken on an average of 12 days 

per year (based on the percentages 

above, respectively, but with some taken 

more or less). As described above, given 

this number of takes spread across a 

year and the nature of the Navy’s 

activities, these takes are not expected 

to typically occur over sequential days. 

• Impacts to these small and resident 

populations of dwarf and pygmy sperm 

whale stocks will be reduced through 

the implementation of the requirements 

in the Hawaii Island Mitigation Area. 

• Kogia spp. are not depleted under 

the MMPA, nor are they listed under the 

ESA. 

• The HSTT activities are not 

expected to occur in an area/time of 

specific importance for reproductive, 

feeding, or other known critical 

behaviors for Kogia spp. and there is no 

designated critical habitat in the HSTT 

Study Area. 

Consequently, the HSTT activities are 

not expected to adversely impact rates 

of recruitment or survival of any of the 

analyzed stocks of Kogia whales (Table 

73 above in this section). 

Beaked Whales 

In Tables 75 and 76 below, for beaked 

whales, we indicate the total annual 

mortality, Level A and Level B 

harassment, and a number indicating 

the instances of total take as a 

percentage of abundance. No Level A 

harassment (PTS and Tissue Damage) 

takes are anticipated. 

BILLING CODE 3510–22–P 


sradovich on DSK3GMQ082PROD with PROPOSALS2

EP26JN18.105</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Table 75. Annual takes of Level B and Level A harassment, mortality for beaked 

tudv area and number indicatim! the instances of total take as a oercenta2:e of 

Instances of indicated types of incidental take 

(not all takes represent separate individuals, 

especially for disturbance) 

level B Harassment 

level A 

Total Takes Abundance 

Harassment 

Species Mortality TOTAL Takes Total Navy Within 

Stock TTS (may TAKES 

Navy EEZ Behavioral also include PTS Tissue (entire (within Abundance Navy E

Disturbance Damage NAVY in and out Abund

location disturbance) Study EEZ) EEZ (HRC) HRC 

(HRC) Area) 

Blainville's 

beaked 

whale 5369 17 0 0 0 5386 4140 989 768 

Hawaiian 

(HRC) Cuvier's 

beaked 

whale 1792 4 0 0 0 1796 1377 345 268 

Hawaiian 

(HRC) 

Longman's 

beaked 

whale 19152 81 0 0 0 19233 14585 3568 277

Hawaiian 

(HRC) 

Note: For the HI take estimates, we compare predicted takes to abundance estimates generated from the same underlying densit

of the C.S. EEZ. Because the portion of the Navy's action area inside the U.S. EEZ is generally concomitant with the study are

estimates in the SARs, and the abundance predicted by the same underlying density estimates is the pref(m-ed abundance to use, 

compare the take to the S:\Rs abundance estimate. 
BILLING CODE 3510–22–C 

Nearly all takes annually for beaked 

under the ESA. 

anticipated. No beaked whales are listed 

injury, serious injury, or mortalities are 

(Tables 75 and 76 above). No PTS, 

behavioral, less than 1 percent are TTS 

whales from Level B harassment are 

Most Level B harassments to beaked 

(

to be in the form of milder responses 

majority of Level B takes are expected 

160 dB SPL (94 percent). Therefore, the 

from received levels between 154 and 

in the HSTT Study Area would result 

whales from hull-mounted sonar (MF1) 

i.e., lower-level exposures that still rise 

exposed to higher received levels. 

effects from takes when animals are 

this section, we anticipate more severe 

qualify as take). As mentioned earlier in 

less severe in the range of responses that 

to the level of take, but would likely be 

For the total instances of all of the 

different types of takes, the numbers 


EP26JN18.106</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Table 76. Annual takes of Level B and Level A harassment, mortality for beaked whales 

HSTT study area and number indicating the instances of total take as a percentage of sto

Instances of indicated types of incidental take 

(not all takes represent separate individuals, 

especially for disturbance) 

level B Harassment level A Total Abundance 

Harassment Takes 

TOTAL NAVY 

TTS (may abundance NM

Behavioral Tissue TAKES SAR

Species Stock also include PTS Mortality (entire in Action 

Disturbance Damage Abund

disturbance) Study Area 2 

Area) SOCAL 1 

Baird's 

beaked CA/OR/WA 2030 14 0 0 0 2044 74 269

whale 

Cuvier's 

beaked CA/OR/WA 11347 79 0 0 0 11426 520 32

whale 

Mesoplodon CA/OR/WA 6109 43 0 0 0 6152 89 304

spp. 

Note: For the SOCAL take estimates, because of the manner in which the Navy action area overlaps the ranges of many MMPA stocks (i.e., a 

Washington state and beyond and abundance may only be predicted within the U.S. EEZ, while the Navy action area is limited to Southern C

but extends beyond the U.S. EEZ), we compare predicted takes to both the abundance estimates for the action area, as well as the SARs. 
30006 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

indicating the instances of total take as 

a percentage of abundance range from 

514 to 545 for Blainville’s beaked whale, 

Cuvier’s beaked whale, and Longman’s 

beaked whale (all Hawaiian stocks), 

with no notable difference in and 

outside of the U.S. EEZ (Table 75). For 

beaked whales off of SOCAL, the 

instances of total take as a percentage of 

abundance are between 76 and 349 as 

compared to the total abundance of 

these far-ranging stocks. However, the 

percentages are 2762, 2197, and 6912 for 

Baird’s beaked whale, Cuvier’s beaked 

whale, and Mesoplodon spp., 

respectively, when compared to the 

abundance within the Navy’s action 

area, which is based on static density 

estimates (Table 76). This means that 

generally, beaked whales might be 

expected to be taken on an average of 1– 

6 days per year, while some individuals 

that might remain in the Navy SOCAL 

action area for extended periods of time 

could be taken on more, but not likely 

as high as 22–28 days per year, or 

potentially more, though not likely as 

high as 69 days per year, for 

Mesoplodon spp. While the likelihood 

and extent of repeated takes for some 

subset of Mesoplodon individuals is 

comparatively high when using the 

Navy’s abundance, this is likely a result 

of the fact that the acoustic modeling 

process does not account for horizontal 

animal movement and thus and 

migration of beaked whales in and out 

the Study Area. The Navy’s abundance 

indicates a population of approximately 

89 Mesoplodon individuals in Southern 

California. However, it is unlikely that 

it is the same 89 individuals that are 

present all year long. Even for those 

beaked whales which show high site 

fidelity, tagging data indicates that they 

can travel tens of km to up to 100 km 

from an initial tagging or sighting 

location (e.g., Schorr et al., 2009, 

Sweeney et al., 2007, etc.). Therefore, 

additional individuals up to a 100 km 

or more from the study area may also at 

some time move into the study area and 

be available to be exposed to Navy 

activities. As a result, the potential for 

repeated exposures of Mesoplodon 

likely falls somewhere in between the 

numbers estimated using the SAR 

abundance and the Navy’s abundance. 

Also, we’d note that NMFS’s 2017 draft 

SAR (Caretta et al., 2017) indicates a 

slight increasing population trend for 

this stock when 2014 survey data are 

considered, lessening the likelihood of 

adverse impacts on rates of recruitment 

or survival, if some small number of 

individuals incur fitness impacts. Given 

the numbers of days within the year that 

they are expected to be taken, some 

subset of SOCAL Mesoplodon beaked 

whale individuals will likely 

occasionally be taken across sequential 

days. However, given the milder 

comparative nature of the majority of 

the anticipated exposures (i.e., the 

received level and the fact that most 

individual exposures would be expected 

not to be of a long duration due to the 

nature of the operations and the moving 

animals), combined with the fact that 

there are ample alternative nearby 

feeding opportunities available for 

odontocetes should disturbances 

interrupt feeding bouts, and the 

evidence that beaked whales often leave 

and area during training exercises but 

return a few days later (Claridge and 

Durban, 2009; Moretti et al., 2009, 2010; 

Tyack et al., 2010, 2011; McCarthy et 

al., 2011), impacts to individual fitness 

that could affect survivorship or 

reproductive success are not 

anticipated. 

Beaked whales have been shown to be 

particularly sensitive to sound and 

therefore have been assigned a lower 

harassment threshold, i.e., a more 

distant distance cutoff (50 km for high 

source level, 25 km for moderate source 

level). This means that many of the 

authorized takes are expected to result 

from lower-level exposures. But we also 

note the growing literature to support 

the fact that marine mammals 

differentiate sources of the same level 

emanating from different distances, and 

exposures from more distant sources are 

likely comparatively less impactful. 

Behavioral responses can range from 

a mild orienting response, or a shifting 

of attention, to flight and panic 

(Richardson, 1995; Nowacek, 2007; 

Southall et al., 2007; Finneran and 

Jenkins, 2012). Research has also shown 

that beaked whales are especially 

sensitive to the presence of human 

activity (Tyack et al., 2011; Pirotta et al., 

2012). Beaked whales have been 

documented to exhibit avoidance of 

human activity or respond to vessel 

presence (Pirotta et al., 2012). Beaked 

whales were observed to react 

negatively to survey vessels or low 

altitude aircraft by quick diving and 

other avoidance maneuvers, and none 

were observed to approach vessels 

(Wursig et al., 1998). Some beaked 

whale vocalizations may overlap with 

the MFAS/HFAS TTS frequency range 

(2–20 kHz). However, as noted above, 

NMFS does not anticipate TTS of a 

serious degree or extended duration to 

occur as a result of exposure to MFAS/ 

HFAS. 

It has been speculated for some time 

that beaked whales might have unusual 

sensitivities to sonar sound due to their 

likelihood of stranding in conjunction 

with MFAS use. Research and 

observations show that if beaked whales 

are exposed to sonar or other active 

acoustic sources they may startle, break 

off feeding dives, and avoid the area of 

the sound source to levels of 157 dB re 

1 mPa, or below (McCarthy et al., 2011). 

Acoustic monitoring during actual sonar 

exercises revealed some beaked whales 

continuing to forage at levels up to 157 

dB re 1 mPa (Tyack et al. 2011). Stimpert 

et al. (2014) tagged a Baird’s beaked 

whale, which was subsequently exposed 

to simulated MFAS. Changes in the 

animal’s dive behavior and locomotion 

were observed when received level 

reached 127 dB re 1mPa. However, 

Manzano-Roth et al. (2013) found that 

for beaked whale dives that continued 

to occur during MFAS activity, 

differences from normal dive profiles 

and click rates were not detected with 

estimated received levels up to 137 dB 

re 1 mPa while the animals were at 

depth during their dives. And in 

research done at the Navy’s fixed 

tracking range in the Bahamas, animals 

were observed to leave the immediate 

area of the anti-submarine warfare 

training exercise (avoiding the sonar 

acoustic footprint at a distance where 

the received level was ‘‘around 140 dB’’ 

SPL, according to Tyack et al. (2011)) 

but return within a few days after the 

event ended (Claridge and Durban, 

2009; Moretti et al., 2009, 2010; Tyack 

et al., 2010, 2011; McCarthy et al., 

2011). Tyack et al. (2011) report that, in 

reaction to sonar playbacks, most 

beaked whales stopped echolocating, 

made long slow ascent to the surface, 

and moved away from the sound. A 

similar behavioral response study 

conducted in Southern California waters 

during the 2010–2011 field season 

found that Cuvier’s beaked whales 

exposed to MFAS displayed behavior 

ranging from initial orientation changes 

to avoidance responses characterized by 

energetic fluking and swimming away 

from the source (DeRuiter et al., 2013b). 

However, the authors did not detect 

similar responses to incidental exposure 

to distant naval sonar exercises at 

comparable received levels, indicating 

that context of the exposures (e.g., 

source proximity, controlled source 

ramp-up) may have been a significant 

factor. The study itself found the results 

inconclusive and meriting further 

investigation. Cuvier’s beaked whale 

responses suggested particular 

sensitivity to sound exposure as 

consistent with results for Blainville’s 

beaked whale. 

Populations of beaked whales and 

other odontocetes on the Bahamas and 

other Navy fixed ranges that have been 


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Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 30007 

operating for decades, appear to be 

stable. Behavioral reactions (avoidance 

of the area of Navy activity) seem likely 

in most cases if beaked whales are 

exposed to anti-submarine sonar within 

a few tens of kilometers, especially for 

prolonged periods (a few hours or more) 

since this is one of the most sensitive 

marine mammal groups to 

anthropogenic sound of any species or 

group studied to date and research 

indicates beaked whales will leave an 

area where anthropogenic sound is 

present (Tyack et al., 2011; De Ruiter et 

al., 2013; Manzano-Roth et al., 2013; 

Moretti et al., 2014). Research involving 

tagged Cuvier’s beaked whales in the 

SOCAL Range Complex reported on by 

Falcone and Schorr (2012, 2014) 

indicates year-round prolonged use of 

the Navy’s training and testing area by 

these beaked whales and has 

documented movements in excess of 

hundreds of kilometers by some of those 

animals. Given that some of these 

animals may routinely move hundreds 

of kilometers as part of their normal 

pattern, leaving an area where sonar or 

other anthropogenic sound is present 

may have little, if any, cost to such an 

animal. Photo identification studies in 

the SOCAL Range Complex, a Navy 

range that is utilized for training and 

testing, have identified approximately 

100 individual Cuvier’s beaked whale 

individuals with 40 percent having been 

seen in one or more prior years, with resightings up to seven years apart 

(Falcone and Schorr, 2014). These 

results indicate long-term residency by 

individuals in an intensively used Navy 

training and testing area, which may 

also suggest a lack of long-term 

consequences as a result of exposure to 

Navy training and testing activities. 

Finally, results from passive acoustic 

monitoring estimated regional Cuvier’s 

beaked whale densities were higher 

than indicated by the NMFS’s broad 

scale visual surveys for the U.S. west 

coast (Hildebrand and McDonald, 2009). 

Based on the findings above, it is clear 

that the Navy’s long-term ongoing use of 

sonar and other active acoustic sources 

has not precluded beaked whales from 

also continuing to inhabit those areas. 

Based on the best available science, the 

Navy and NMFS believe that beaked 

whales that exhibit a significant TTS or 

behavioral reaction due to sonar and 

other active acoustic training or testing 

activities would generally not have 

long-term consequences for individuals 

or populations. 

NMFS does not expect strandings, 

serious injury, or mortality of beaked 

whales to occur as a result of training 

activities. Stranding events coincident 

with Navy MFAS use in which exposure 

to sonar is believed to have been a 

contributing factor were detailed in the 

Stranding and Mortality section of this 

proposed rule. However, for some of 

these stranding events, a causal 

relationship between sonar exposure 

and the stranding could not be clearly 

established (Cox et al., 2006). In other 

instances, sonar was considered only 

one of several factors that, in their 

aggregate, may have contributed to the 

stranding event (Freitas, 2004; Cox et 

al., 2006). Because of the association 

between tactical MFAS use and a small 

number of marine mammal strandings, 

the Navy and NMFS have been 

considering and addressing the 

potential for strandings in association 

with Navy activities for years. In 

addition to the proposed mitigation 

measures intended to more broadly 

minimize impacts to marine mammals, 

the reporting requirements set forth in 

this rule ensure that NMFS is notified 

if a stranded marine mammal is found 

(see General Notification of Injured or 

Dead Marine Mammals in the regulatory 

text below). Additionally, through the 

MMPA process (which allows for 

adaptive management), NMFS and the 

Navy will determine the appropriate 

way to proceed in the event that a 

causal relationship were to be found 

between Navy activities and a future 

stranding. 

Biologically important areas for small 

and resident populations of Cuvier’s 

and Blainville’s beaked whales will be 

protected by the Hawaii Island 

Mitigation Area that limits the use of 

mid-frequency active anti-submarine 

warfare sensor bins MF1 and MF4 and 

where the Navy will not use explosives 

during testing and training (e.g., surfaceto-surface or air-to-surface missile and 

gunnery events, BOMBEX, and mine 

neutralization). 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from the Navy’s 

activities are not expected to adversely 

affect beaked whales taken through 

effects on annual rates of recruitment or 

survival. 

• No mortalities of beaked whales are 

proposed for authorization or 

anticipated to occur. 

• No PTS or injury of beaked whales 

from acoustic or explosives stressors are 

proposed for authorization or 

anticipated to occur. 

• While the majority of takes are 

caused by exposure during ASW 

activities the impacts from these 

exposures are not expected to have 

either significant or long-term effects 

because (and as discussed above): 

Æ ASW activities typically involve 

fast-moving assets (relative to marine 

mammals swim speeds) and individuals 

are not expected to be exposed either for 

long periods within a day or over many 

sequential days. 

Æ As discussed, the majority of the 

harassment takes result from hullmounted sonar during MTEs. When 

distance cutoffs are applied for beaked 

whales, this means that all of the takes 

from hull-mounted sonar (MF1) result 

from above exposure 154 dB. However, 

the majority (e.g., 94 percent) of the 

takes results from exposures below 160 

dB. The majority of the takes have a 

relatively lower likelihood to have 

severe impacts. 

• As described in more detail above 

(Tables 75 and 76), the scale of the 

effects are such that individuals in these 

stocks are likely taken in an average of 

1–6 days per year, while a subset of 

beaked whale individuals that remain in 

the SOCAL action area for a substantial 

portion of the year could be taken in 

more, though not likely above 22–28 

days per year, with Mesolplodon 

individuals potentially taken more, 

though not likely above 69 days per 

year. While the likelihood and extent of 

repeated takes for some subset of 

Mesoplodon individuals is 

comparatively high, we note that the 

population trend for this stock is 

increasing slightly, lessening the 

likelihood of adverse impacts on rates of 

recruitment or survival. While some of 

the individuals in SOCAL may 

occasionally be taken in sequential 

days, because of the nature of the 

exposures and the other factors 

discussed above, any impacts to 

individual fitness would be limited and 

with the potential to accrue to no more 

than a limited number of individuals 

and would not be expected to affect 

rates of recruitment or survival. 

• Impacts to BIAs for small and 

resident populations of Cuvier’s and 

Blainville’s beaked whales will be 

reduced through implementation of 

requirements in the Hawaii Island 

Mitigation Area. 

Consequently, the activities are not 

expected to adversely impact rates of 

recruitment or survival of any of the 

beaked whale stocks analyzed (Tables 

75 and 76 above in this section). 

Odontocetes (Small Whales and 

Dolphins) 

In Tables 77 and 78 below, for 

odontocetes (in this section odontocetes 

refers specifically to the small whales 

and dolphins indicated in Tables 77 and 

78), we indicate the total annual 

mortality, Level A and Level B 

harassment, and a number indicating 


sradovich on DSK3GMQ082PROD with PROPOSALS2

EP26JN18.107</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Table 77. Annual takes of Level Band Level A harassment, mortality for odontocetes in the H

study area and number indicating the instances of total take as a percentage of stock abundan

Instances of indicated types of incidental take 

(not all takes represent separate individuals, 

especially for disturbance) 

level B Harassment level A Total Takes Abundance Instance of to

Harassment of a

Species TOTAL Takes Total Navy Within Total take as 

Stock TIS (may Mortality TAKES percentage Behavioral Tissue (within Abundance Navy EEZ 

Navy EEZ also include PTS (entire of total Navy 

location Disturbance disturbance) Damage Study NAVY in and out Abundance abundance 

(HRC) Area) EEZ) EEZ (HRC) HRC (HRC) 

Bottlenose 

dolphin 

Hawaiian 3196 133 0 0 0 3329 2481 1528 1442 218 

Pelagic 

(HRC) 

Bottlenose 

dolphin 

Kauai & 534 31 0 0 0 565 264 184 184 307 

Niihau 

(HRC) 

Bottlenose 

dolphin 8600 62 1 0 0 8663 8376 741 741 1169 

Oahu 

(HRC) 

Bottlenose 

dolphin 349 10 0 0 0 359 316 189 189 190 

4-lsland 

(HRC) 

Bottlenose 

dolphin 74 5 0 0 0 79 42 131 131 60 

Hawaii 

(HRC) 

False killer 

whale 

Hawaii 999 42 0 0 0 1041 766 645 507 161 

Pelagic 

(HRC) 

False killer 

whale 

Main Hawaiian 572 16 0 0 0 588 476 147 147 400 

Islands Insular 

(HRC) 

EP26JN18.108</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

False killer 

whale 

Northwestern 365 16 0 0 0 381 280 215 169 

Hawaiian 

Islands 

(HRC) 

Fraser's 

dolphin 39784 1289 2 0 0 41075 31120 5408 18763 

Hawaiian 

(HRC) 

Killer whale 

Hawaiian 118 6 0 0 0 124 93 69 54 

(HRC) 

Melonheaded 

whale 

Hawaiian 3260 231 0 0 0 3491 2557 1782 1782 

Islands 

(HRC) 

Melonheaded 

whale 

Kohala 341 10 0 0 0 351 182 447 447 

Resident 

(HRC) 

Pantropical 

spotted 

dolphin 3767 227 0 0 0 3994 2576 2405 2405 

Hawaii Island 

(HRC) 

Pantropical 

spotted 

dolphin 9973 476 0 0 0 10449 7600 5462 4637 

Hawaii 

Pelagic 

(HRC) 

Pantropical 

spotted 

dolphin 4284 45 0 0 0 4329 4194 372 372 

Oahu 

(HRC) 

Pantropical 

spotted 

dolphin 702 17 0 0 0 719 634 657 657 

4-lsland 

(HRC) 

Pygmy killer 

whale 8122 401 0 0 0 8523 6538 4928 3931 

Hawaiian 

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(HRC) 

Pygmy killer 

whale 

Tropical 710 50 0 0 0 760 490 159 23 

(HRC) 

Risso's 

dolphin 8950 448 0 0 0 9398 7318 1210 4199 

Hawaiian 

(HRC) 

Roughtoothed 

dolphin 6112 373 0 0 0 6485 4859 3054 2808 

Hawaiian 

(HRC) 

Short-finned 

pilot whale 12499 433 1 0 0 12933 9946 6433 5784 

Hawaiian 

(HRC) 

Spinner 

dolphin 

Hawaii Island 279 12 0 0 0 291 89 629 629 

(HRC) 

Spinner 

dolphin 

Hawaii 4331 202 0 0 0 4533 3491 2885 2229 

Pelagic 

(HRC) 

Spinner 

dolphin 

Kauai & 1683 63 0 0 0 1746 812 604 604 

Niihau 

(HRC) 

Spinner 

dolphin 

Oahu & 4- 1790 34 1 0 0 1825 1708 354 354 

Island 

(HRC) 

Striped 

dolphin 

Hawaiian 

7379 405 0 0 0 7784 6034 4779 3646 

(HRC) 

Note: For the HI take estimates, we compare predicted takes to abundance estimates generated from the same underlying density estim

of the C.S. EEZ. Because the portion of the Navy's action area inside the U.S. EEZ is generally concomitant with the study area used 

estimates in the SARs, and the abundance predicted by the same underlying density estimates is the prcfcrTed abundance to usc, there 

compare the take to the S:\Rs abundance estimate. 

EP26JN18.110</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Table 78. Annual takes of Level B and Level A harassment, mortality for odontocetes in 

study area and number indicating the instances of total take as a percentage of stock abu

Instances of indicated types of incidental take 

(not all takes represent separate individuals, 

especially for disturbance) 

level B Harassment level A Harassment Total Takes Abundance 

TTS (may TOTAL NAVY 

Behavioral TAKES Abundanc NMFS 

Species Stock Disturbanc also include PTS Tissue Mortality (entire e in Action Abu

disturbance Damage Study Area 

e 

) 

Area) SOCAL 1 

Bottlenose California 1771 38 0 0 0 1809 238 5

dolphin Coastal 

Bottlenose CA/OR/WA 51727 3695 3 0 0 55425 5946 19

dolphin Offshore 

Eastern 

North 

Killer whale Pacific 96 11 0 0 0 107 4 2

(ENP) 

Offshore 

ENP 

Transient/ 

Killer whale West 179 20 0 0 0 199 30 24

Coast 

Transient 

Long-beaked 

common California 233485 13787 18 2 0 247292 10258 101

dolphin 

Northern right 

whale CA/OR/WA 90052 8047 10 1 0 98110 7705 26

dolphin 
BILLING CODE 3510–22–C 

Nearly all takes annually for 

whales (Main Hawaiian Islands Insular) 

mortalities are anticipated. False killer 

78 above). No serious injuries or 

(less than 1 percent PTS) (Tables 77 and 

harassment either behavioral or TTS 

odonotocetes are from Level B 

will further inform our final decision. 

and the outcome of that consultation 

Section 7 consultation under the ESA 

is currently engaged in an internal 

and depleted under the MMPA. NMFS 

are listed as endangered under the ESA 

Most Level B harassments to 

odontocetes from hull-mounted sonar section, we anticipate more severe 

exposures). As mentioned earlier in this 

responses compared to higher level 

expected to be in the form of milder 

the majority of Level B takes are 

and 166 dB SPL (85 percent). Therefore, 

result from received levels between 154 

(MF1) in the HSTT Study Area would 


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Pacific whiteCA/OR/WA 69245 6093 5 0 0 75343 6626 26

sided dolphin 

Risso's dolphin CA/OR/WA 116143 10118 9 0 0 126270 7784 63

Short-beaked 

common CA/OR/WA 1374048 118525 79 10 2 1492664 261438 969

dolphin 

Short-finned CA/OR/WA 1789 124 1 0 0 1914 208 8

pilot whale 

Striped CA/OR/WA 163640 11614 3 0 0 175257 39862 29

dolphin 

Note: For the SOCAL take estimates, because of the manner in which the Navy action area overlaps the ranges of many MMPA stocks (i.e., a 

Washington state and beyond and abundance may only be predicted within the U.S. EEZ, while the Navy action area is limited to Southern C

but extends beyond the U.S. EEZ), we compare predicted takes to both the abundance estimates for the action area, as well as the SARs. 
Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 30013 

effects from takes when animals are 

exposed to higher received levels. 

For the total instances of all of the 

different types of takes, the numbers 

indicating the instances of total take for 

odontocetes addressed in this section as 

a percentage of abundance range from 

14 to 1,169 for Hawaiian stocks (Table 

77). For most odontocetes off SOCAL, 

the instances of total take as a 

percentage of abundance are between 45 

and 1,273 (Table 78). However, the 

percentages are 2,675 and 2,411 for 

Killer whale and Long-beaked common 

dolphin, respectively, when compared 

to the abundance within the Navy 

action area, which is based on static 

density estimates (Table 78). The 

percentages are 1,993 and 1,622 for 

Risso’s dolphin when compared to the 

total U.S. EEZ abundance (from the 

SARs) and to the abundance within the 

Navy action area, respectively, and 

2,811 for Bottlenose dolphin (CA/OR/ 

WA offshore stock) when compared to 

the total abundance. This means that 

generally, Hawaiian and SOCAL 

odontocetes stocks might be expected to 

be taken an average of 2–13 days per 

year, while some of a subset of 

individuals of four stocks (Offshore 

bottlenose dolphins, killer whales, longbeaked common dolphin, and Risso’s 

dolphin) that might remain in the Navy 

SOCAL action area for extended periods 

of time could be taken on more, 17 to 

27 days per year. It is notable that for 

the offshore stock of bottlenose dolphins 

and for Risso’s dolphins, the SAR 

abundances are actually less than the 

Navy action area abundances, likely 

because these are more offshore species 

and the navy abundance captures the 

abundance generated outside the U.S. 

EEZ from the Navy action are density 

estimates, and therefore the percentages 

are higher—but either way these stock 

comparisons fall within the general 

bounds discussed above. We further 

note that long-beaked common dolphin, 

which have a high percentage generated 

from a high number of takes and a high 

abundance, have an increasing 

population trend (Caretta et al., 2017), 

further lessening the likelihood of 

adverse impacts to rates of recruitment 

or survival. The majority of the takes are 

not from higher level exposures from 

which more severe responses would be 

expected. Given the numbers of days 

within the year that they are expected 

to be taken, some subset of individuals 

will likely occasionally be taken across 

sequential days, however, given the 

milder to moderate nature of the 

majority of the anticipated exposures 

(i.e., the received level and the fact that 

most individual exposures would be 

expected not to be of a long duration 

due to the nature of the operations and 

the moving animals), combined with the 

fact that there are ample alternative 

nearby feeding opportunities available 

for odontocetes should disturbances 

interrupt feeding bouts, impacts to 

individual fitness that could affect 

survivorship or reproductive success are 

not anticipated. 

Research and observations show that 

if delphinids are exposed to sonar or 

other active acoustic sources they may 

react in a number of ways depending on 

their experience with the sound source 

and what activity they are engaged in at 

the time of the acoustic exposure. 

Delphinids may not react at all until the 

sound source is approaching within a 

few hundred meters to within a few 

kilometers depending on the 

environmental conditions and species. 

Delphinids that are exposed to activities 

that involve the use of sonar and other 

active acoustic sources may alert, ignore 

the stimulus, change their behaviors or 

vocalizations, avoid the sound source by 

swimming away or diving, or be 

attracted to the sound source 

(Richardson, 1995; Nowacek, 2007; 

Southall et al., 2007; Finneran and 

Jenkins, 2012). 

Many of the recorded delphinid 

vocalizations overlap with the MFAS/ 

HFAS TTS frequency range (2–20 kHz); 

however, as noted above, NMFS does 

not anticipate TTS of a serious degree or 

extended duration to occur as a result of 

exposure to MFAS/HFAS. 

Identified important areas for 

odontocetes will be protected by the 

Navy’s mitigation areas. The size of the 

4-Islands Region Mitigation Area would 

expand to include an area north of Maui 

and Molokai and overlaps an area 

identified as a BIA for the endangered 

Main Hawaiian Islands insular false 

killer whales (Baird et al., 2015; Van 

Parijs, 2015) (see Figure 5.4–3, in 

Chapter 5 Mitigation Areas for Marine 

Mammals in the Hawaii Range Complex 

of the HSTT DEIS/OEIS). The 4-Islands 

Region Mitigation Area provides partial 

protection for identified biologically 

important area for dolphin species 

(small and resident populations) 

including common bottlenose dolphin, 

pantropical spotted dolphin, and 

spinner dolphin by not using midfrequency active anti-submarine warfare 

sensor MF1. The Navy’s Hawaii Island 

Mitigation Area also provides additional 

protection for identified biologically 

important areas (small and resident 

populations) for Main Hawaiian Islands 

insular false killer whales, pygmy killer 

whale, melon-headed whale, shortfinned pilot whale, and dolphin species 

(common bottlenose dolphin, 

pantropical spotted dolphin, spinner 

dolphin, rough-toothed dolphins) by 

limiting the use of mid-frequency active 

anti-submarine warfare sensor bins MF1 

and MF4 and not using explosives 

during testing and training (e.g., surfaceto-surface or air-to-surface missile and 

gunnery events, BOMBEX, and mine 

neutralization). 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from Navy’s activities 

are not expected to adversely affect 

dolphins and small whales taken 

through effects on annual rates of 

recruitment or survival. 

• As described in the ‘‘Serious Injury 

or Mortality’’ section (Table 68), 1.2 

mortalities annually over five years is 

proposed for authorization for shortbeaked common dolphin (CA/OR/WA 

stock). The proposed mortality for shortbeaked common dolphin (CA/OR/WA 

stock) falls below the insignificance 

threshold and, therefore, we consider 

the addition an insignificant 

incremental increase to human-caused 

mortality. 

• There are no PTS or injury from 

acoustic or explosive sources proposed 

for authorization or anticipated to occur 

for most odontocetes. As described 

above, any PTS that may occur is 

expected to be of a relatively smaller 

degree because of the unlikelihood that 

animals would be close enough for a 

long enough amount of time to incur 

more severe PTS (for sonar) and the 

anticipated effectiveness of mitigation 

in preventing very close exposures for 

explosives. 

• Large threshold shifts are not 

anticipated for these activities because 

of the unlikelihood that animals will 

remain within the ensonified area (due 

to the short duration of the majority of 

exercises, the speed of the vessels 

(relative to marine mammals swim 

speeds), and the short distance within 

which the animal would need to 

approach the sound source) at high 

levels for the duration necessary to 

induce larger threshold shifts. 

• While the majority of takes are 

caused by exposure during ASW 

activities, the impacts from these 

exposures are not expected to have 

either significant or long-term effects 

because (and as discussed above): 

Æ ASW activities typically involve 

fast-moving assets (relative to marine 

mammal swim speeds) and individuals 

are not expected to be exposed either for 

long periods within a day or over many 

sequential days. 

Æ As discussed, the majority of the 

harassment takes result from hullmounted sonar during MTEs. When 


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30014 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

distance cutoffs are applied for 

odontocetes, this means that all of the 

takes from hull-mounted sonar (MF1) 

result from above exposure 154 dB. 

However, the majority (e.g., 85 percent) 

of the takes results from exposures 

below 166 dB. The majority of the takes 

are not from higher level exposures from 

which more severe responses would be 

expected. 

• As described in more detail above 

(Tables 77 and 78) for the stocks 

addressed in this section, the scale of 

the effects are such that individuals of 

most Hawaiian and SOCAL odontocete 

stocks are likely taken an average of 2– 

13 days per year, while killer whale, 

long-beaked common dolphin, and 

Risso’s dolphin individuals that remain 

in the SOCAL action area could be taken 

an average of 17–27 days per year. 

Bottlenose dolphin (CA/OR/WA 

offshore stock) could be taken an 

average of 10–29 days per year. While 

some of the individuals in SOCAL may 

occasionally be taken in sequential 

days, because of the nature of the 

exposures and the other factors 

discussed above, any impacts to 

individual fitness would be limited and 

with the potential to accrue to no more 

than a limited number of individuals 

and would not be expected to affect 

rates of recruitment or survival. We 

further note that long-beaked common 

dolphin have an increasing population 

trend. 

• The 4-Islands Region Mitigation 

Area provides partial protection for 

identified biologically important area 

for dolphin species (small and resident 

populations) by not using midfrequency active anti-submarine warfare 

sensor MF1. 

• The Navy’s Hawaii Island 

Mitigation Area also provides additional 

protection for identified biologically 

important areas (small and resident 

populations) for endangered Main 

Hawaiian Islands insular false killer 

whales, pygmy killer whale, melonheaded whale, short-finned pilot whale, 

and dolphin species by limiting the use 

of mid-frequency MF1 and MF4 and not 

using explosives during testing and 

training. 

• All odontocetes in the HSTT Study 

Area with the exception of endangered 

Main Hawaiian Islands Insular false 

killer whale are not depleted under the 

MMPA, nor are they listed under the 

ESA. 

Consequently, the activities are not 

expected to adversely impact rates of 

recruitment or survival of any of the 

stocks of analyzed odontocete species 

(Table 74, above in this section). 

Porpoise 

In Table 79 below, for Dall’s porpoise, 

we indicate the total annual mortality, 

Level A and Level B harassment, and a 

number indicating the instances of total 

take as a percentage of abundance. 

Overall, takes from Level A harassment 

(PTS and Tissue Damage) account for 

less than one percent of all total takes. 

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Nearly all takes annually for Dall’s 

injury (tissue damage) serious injury or 

harassment (PTS) (Table 79 above). No 

percent of all takes are Level A 

either behavioral or TTS. Less than 1 

porpoises are from Level B harassment 

porpoise are not listed under the ESA. 

mortalities are anticipated. Dall’s 

Most Level B harassments to Dall’s 

and 166 dB SPL (85 percent). Therefore, 

result from received levels between 154 

(MF1) in the HSTT Study Area would 

porpoise from hull-mounted sonar 

exposed to higher received levels. 

effects from takes when animals are 

section, we anticipate more severe 

exposures. As mentioned earlier in this 

responses compared to higher level 

expected to be in the form of milder 

the majority of Level B takes are 


EP26JN18.112</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Table 79: Annual takes of Level B and Level A harassment, mortality for porpoises in SOC

area and number indicating the instances of total take as a percentage of stock abundance. 

Instances of indicated types of incidental take (not 

all takes represent separate individuals, especially 

for disturbance) 

Level B Harassment Level A Total Abundance 

Harassment Takes 

TOTAL NAVY 

NM

ITS (may TAKES abundance Behavioral Tissue SAR

Species Stock also include PTS Mortality (entire in Action Disturbance Damage Abund

disturbance) Study Area 2 

Area) SOCAL 1 

Dall's 

CA/OR/WA 14482 29891 209 0 0 44582 2054 257

porpoise 

Note: For the SOCAL take estimates, because of the manner in which the Navy action area overlaps the ranges of many :VlMPi\ stocks sto

\Vashington state and beyond and abundance may only be predicted within the LX EEZ, while the Navy action area is limited to Southern Calif

e>.1:cnds beyond the U.S. EEZ), compare predicted takes to both the abundance estimates tor the action area, as well the SARs. 
30016 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

The majority of Level B takes are 

expected to be in the form of milder to 

moderate responses. As mentioned 

earlier in this section, we anticipate 

more severe effects from takes when 

animals are exposed to higher received 

levels. 

For the total instances of all of the 

different types of takes, the numbers 

indicating the instances of total take for 

Dall’s porpoise as a percentage of 

abundance is 173 when compared to the 

total abundance and 2,170 when 

compared to the abundance within the 

Navy action area, which is based on 

static density estimates (Table 79). This 

means that generally, Dall’s porpoise 

might be expected to be taken on an 

average of 2 days per year, while some 

subset of individuals that might remain 

in the Navy SOCAL action area for 

extended periods of time could be taken 

on more like an average of 22 days per 

year. Occasional mild to moderate 

behavioral reactions are unlikely to 

cause long-term consequences for 

individual animals or populations, and 

because of the overall number of likely 

days taken and the nature of the 

operations, exposures are generally not 

expected to occur on many sequential 

days. Impacts to individual fitness that 

could affect survivorship or 

reproductive success are not 

anticipated. 

Animals that experience hearing loss 

(TTS or PTS) may have reduced ability 

to detect relevant sounds such as 

predators, prey, or social vocalizations. 

Some porpoise vocalizations might 

overlap with the MFAS/HFAS TTS 

frequency range (2–20 kHz). Recovery 

from a threshold shift (TTS; partial 

hearing loss) can take a few minutes to 

a few days, depending on the exposure 

duration, sound exposure level, and the 

magnitude of the initial shift, with 

larger threshold shifts and longer 

exposure durations requiring longer 

recovery times (Finneran et al., 2005; 

Mooney et al., 2009a; Mooney et al., 

2009b; Finneran and Schlundt, 2010). 

More severe shifts may not fully recover 

and thus would be considered PTS. TTS 

and PTS thresholds for high-frequency 

cetaceans, including Dall’s porpoises, 

are lower than for all other marine 

mammals, which leads to a higher 

number of estimated impacts relative to 

the number of animals exposed to the 

sound as compared to other hearing 

groups (e.g., mid-frequency cetaceans). 

Dall’s porpoises that do experience 

hearing loss (i.e., TTS or PTS) from 

sonar sounds may have a reduced 

ability to detect biologically important 

sounds until their hearing recovers, but 

recovery time is not expected to be long 

for any small amount of TTS incurred 

from these activities, as described 

above. TTS would be recoverable and 

PTS would leave some residual hearing 

loss. During the period that a Dall’s 

porpoise had hearing loss, biologically 

important sounds could be more 

difficult to detect or interpret. 

Odontocetes, including Dall’s porpoises, 

use echolocation clicks to find and 

capture prey. These echolocation clicks 

are at frequencies above 100 kilohertz in 

Dall’s porpoises. Therefore, 

echolocation is unlikely to be affected 

by a threshold shift at lower frequencies 

and should not affect a Dall’s porpoise 

ability to locate prey or rate of feeding. 

The information available on harbor 

porpoise behavioral reactions to human 

disturbance (a closely related species) 

suggests that these species may be more 

sensitive and avoid human activity, and 

sound sources, to a longer range than 

most other odontocetes. This would 

make Dall’s porpoises less susceptible to 

hearing loss; therefore, it is likely that 

the quantitative analysis over-predicted 

hearing loss impacts (i.e., TTS and PTS) 

in Dall’s porpoises. 

Harbor porpoises (similar to Dall’s 

porpoise) have been observed to be 

especially sensitive to human activity 

(Tyack et al., 2011; Pirotta et al., 2012). 

The information currently available 

regarding harbor porpoises suggests a 

very low threshold level of response for 

both captive (Kastelein et al., 2000; 

Kastelein et al., 2005) and wild 

(Johnston, 2002) animals. Southall et al. 

(2007) concluded that harbor porpoises 

are likely sensitive to a wide range of 

anthropogenic sounds at low received 

levels (∼ 90 to 120 dB). Research and 

observations of harbor porpoises for 

other locations show that this species is 

wary of human activity and will display 

profound avoidance behavior for 

anthropogenic sound sources in many 

situations at levels down to 120 dB re 

1 mPa (Southall, 2007). Harbor porpoises 

routinely avoid and swim away from 

large motorized vessels (Barlow et al., 

1988; Evans et al., 1994; Palka and 

Hammond, 2001; Polacheck and 

Thorpe, 1990). Harbor porpoises may 

startle and temporarily leave the 

immediate area of the training or testing 

until after the event ends. 

ASW training activities using hull 

mounted sonar proposed for the HSTT 

Study Area generally last for only a few 

hours. Some ASW exercises can 

generally last for 2–10 days, or as much 

as 21 days for an MTE-Large Integrated 

ASW (see Table 4). For these multi-day 

exercises there will be extended 

intervals of non-activity in between 

active sonar periods. In addition, the 

Navy does not generally conduct ASW 

activities in the same locations. Given 

the average length of ASW events (times 

of continuous sonar use) and typical 

vessel speed, combined with the fact 

that the majority of porpoises in the 

HSTT Study Area would not likely 

remain in an area for successive days, it 

is unlikely that an animal would be 

exposed to active sonar at levels likely 

to result in a substantive response (e.g., 

interruption of feeding) that would then 

be carried on for more than one day or 

on successive days. 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from Navy’s activities 

are not expected to adversely affect 

Dall’s porpoise taken through effects on 

annual rates of recruitment or survival. 

• As described above, any PTS that 

may occur is expected to be of a 

relatively smaller degree because of the 

unlikelihood that animals would be 

close enough for a long enough amount 

of time to incur more severe PTS (for 

sonar) and the anticipated effectiveness 

of mitigation in preventing very close 

exposures for explosives. 

• Large threshold shifts are not 

anticipated for these activities because 

of the unlikelihood that animals will 

remain within the ensonified area (due 

to the short duration of the majority of 

exercises, the speed of the vessels 

(relative to marine mammals swim 

speeds), and the short distance within 

which the animal would need to 

approach the sound source) at high 

levels for the duration necessary to 

induce larger threshold shifts. 

• While the majority of takes are 

caused by exposure during ASW 

activities, the impacts from these 

exposures are not expected to have 

either significant or long-term effects 

because (and as discussed above): 

Æ ASW activities typically involve 

fast-moving assets (relative to marine 

mammal swim speeds) and individuals 

are not expected to be exposed either for 

long periods within a day or over many 

sequential days. As discussed, the 

majority of the harassment takes result 

from hull-mounted sonar during MTEs. 

When distance cutoffs are applied for 

odontocetes, this means that all of the 

takes from hull-mounted sonar (MF1) 

result from above exposure 154 dB. 

However, the majority (e.g., 85 percent) 

of the takes results from exposures 

below 166 dB. The majority of the takes 

are not from higher level exposures from 

which more severe responses would be 

expected. 

• As described in detail above (Table 

79), the scale of the effects are such that 

individuals of Dall’s porpoise might be 

expected to be taken on an average of 2 

days per year, while some subset of 


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individuals that might remain in the 

Navy SOCAL action area for extended 

periods of time could be taken on more 

like an average of 22 days per year. 

Because of the nature of the exposures 

and the other factors discussed above, 

any impacts to individual fitness would 

be limited and with the potential to 

accrue to no more than a limited 

number of individuals and would not be 

expected to affect rates of recruitment or 

survival. 

• Dall’s porpoise in the HSTT Study 

Area are not depleted under the MMPA, 

nor are they listed under the ESA. 

Consequently, the activities are not 

expected to adversely impact rates of 

recruitment or survival of any of the 

Dall’s porpoise stock (CA/OR/WA). 

Pinnipeds 

In Tables 80 and 81 below, for 

pinnipeds, we indicate the total annual 

mortality, Level A and Level B 

harassment, and a number indicating 

the instances of total take as a 

percentage of abundance. Overall, takes 

from Level A harassment (PTS and 

Tissue Damage) account for less than 

one percent of all total takes. 

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Nearly all takes annually for 

No, injury, serious injury, or mortalities 

percent PTS) (Tables 80 and 81 above). 

either behavioral or TTS (less than 1 

pinnipeds are from Level B harassment 

consultation under the ESA and the 

engaged in an internal Section 7 

under the MMPA. NMFS is currently 

endangered under the ESA and depleted 

and Guadalupe fur seal are listed as 

are anticipated. Hawaiian monk seal 

closed soon. 

lions, not an ESA-listed species, will be 

Separately, the UME for California sea 

UME for Guadalupe fur seal is ongoing. 

further inform our final decision. The 

outcome of that consultation will 


EP26JN18.114</GPH>sradovich on DSK3GMQ082PROD with PROPOSALS2

Table 81. Annual takes of Level B and Level A harassment, mortality for pinnipeds for SOC

study area and number indicating the instances of total take as a percentage of stock abund

Instances of indicated types of incidental take 

(not all takes represent separate individuals, 

especially for disturbance) 

level B Harassment level A Total Takes Abundance 

Harassment 

TOTAL NAVY 

TIS (may TAKES abundance NMFSSA

Behavioral Tissue 

Species Stock also include PTS Mortality (entire in Action Abundan

Disturbance disturbance) Damage Study Area 2 

Area) SOCAL 1 

California sea u.s. 113419 4789 87 9 1 118305 4085 29675

lion 

Guadalupe fur Mexico 1442 15 0 0 0 1457 1171 2000

seal 

Northern fur California 15167 124 1 0 0 15292 886 1405

seal 

Harbor seal California 2450 2994 8 0 0 5452 321 3096

Northern California 42916 17955 97 2 0 60970 4108 17900

elephant seal 

Note: For the SOCAL take estimates, because of the manner in which the Navy action area overlaps the ranges of many MMPA stocks (i.e., a stoc

Washington state and beyond and abundance may only be predicted within the U.S. EEZ, while the Navy action area is limited to Southern Califo

but extends beyond the U.S. EEZ), we compare predicted takes to both the abundance estimates for the action area, as well as the SARs. 
Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 30019 

Most Level B harassments to 

pinnipeds from hull-mounted sonar 

(MF1) in the HSTT Study Area would 

result from received levels between 160 

and 172 dB SPL (83 percent). Therefore, 

the majority of Level B takes are 

expected to be in the form of milder to 

moderate responses. As mentioned 

earlier in this section, we anticipate 

more severe effects from takes when 

animals are exposed to higher received 

levels. 

For the total instances of all of the 

different types of takes, the numbers 

indicating the instances of total take for 

pinnipeds as a percentage of abundance 

ranges from 7 to 124 when compared to 

the total abundance (Tables 80 and 81). 

However, for most pinnipeds off 

SOCAL, the instance of total take as a 

percentage of abundance are between 

1,484 and 2,896 when compared to the 

abundance within the Navy action area, 

which is based on static density 

estimates (Table 81). This means that 

generally, pinnipeds might be expected 

to be taken on an average of less than 

2 days per year. However, some subset 

of individuals of the California sea lion, 

Northern fur seal, and harbor seal stocks 

that might remain in the Navy SOCAL 

action area for extended periods of time 

could be taken on more like an average 

of 29, 18, and 17 days per year, 

respectively. The majority of the takes 

are not from higher level exposures from 

which more severe responses would be 

expected. Given the numbers of days 

within the year that they are expected 

to be taken, some subset of individuals, 

particularly California sea lions will 

likely occasionally be taken across 

sequential days, however, given the 

milder to moderate nature of the 

majority of the anticipated exposures 

(i.e., the received level and the fact that 

most individual exposures would be 

expected not to be of a long duration 

due to the nature of the operations and 

the moving animals), impacts to 

individual fitness that could affect 

survivorship or reproductive success are 

not anticipated. We note that for 

California sea lions there is an 

increasing population trend. 

Research and observations show that 

pinnipeds in the water may be tolerant 

of anthropogenic noise and activity (a 

review of behavioral reactions by 

pinnipeds to impulsive and nonimpulsive noise can be found in 

Richardson et al., 1995 and Southall et 

al., 2007). Available data, though 

limited, suggest that exposures between 

approximately 90 and 140 dB SPL do 

not appear to induce strong behavioral 

responses in pinnipeds exposed to nonpulse sounds in water (Jacobs and 

Terhune, 2002; Costa et al., 2003; 

Kastelein et al., 2006c). Based on the 

limited data on pinnipeds in the water 

exposed to multiple pulses (small 

explosives, impact pile driving, and 

seismic sources), exposures in the 

approximately 150 to 180 dB SPL range 

generally have limited potential to 

induce avoidance behavior in pinnipeds 

(Harris et al., 2001; Blackwell et al., 

2004; Miller et al., 2004). If pinnipeds 

are exposed to sonar or other active 

acoustic sources they may react in a 

number of ways depending on their 

experience with the sound source and 

what activity they are engaged in at the 

time of the acoustic exposure. Pinnipeds 

may not react at all until the sound 

source is approaching within a few 

hundred meters and then may alert, 

ignore the stimulus, change their 

behaviors, or avoid the immediate area 

by swimming away or diving. Effects on 

pinnipeds in the HSTT Study Area that 

are taken by Level B harassment, on the 

basis of reports in the literature as well 

as Navy monitoring from past activities, 

will likely be limited to reactions such 

as increased swimming speeds, 

increased surfacing time, or decreased 

foraging (if such activity were 

occurring). Most likely, individuals will 

simply move away from the sound 

source and be temporarily displaced 

from those areas, or not respond at all. 

In areas of repeated and frequent 

acoustic disturbance, some animals may 

habituate or learn to tolerate the new 

baseline or fluctuations in noise level. 

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., 2003). While some 

animals may not return to an area, or 

may begin using an area differently due 

to training and testing activities, most 

animals are expected to return to their 

usual locations and behavior. Given 

their documented tolerance of 

anthropogenic sound (Richardson et al., 

1995 and Southall et al., 2007), repeated 

exposures of individuals (e.g., harbor 

seals) to levels of sound that may cause 

Level B harassment are unlikely to 

result in hearing impairment or to 

significantly disrupt foraging behavior. 

As stated above, pinnipeds may 

habituate to or become tolerant of 

repeated exposures over time, learning 

to ignore a stimulus that in the past has 

not accompanied any overt threat. 

Thus, even repeated Level B 

harassment of some small subset of an 

overall stock is unlikely to result in any 

significant realized decrease in fitness to 

those individuals, and would not result 

in any adverse impact to the stock as a 

whole. 

The Navy’s testing and training 

activities do occur in areas of specific 

importance, critical habitat for Hawaiian 

monk seals. However, monk seals in the 

main Hawaiian islands have increased 

while the Navy has continued its 

activities. The Hawaiian monk seal 

overall population trend has been on a 

decline from 2004 through 2013, with 

the total number of Hawaiian monk 

seals decreasing by 3.4 percent per year 

(Carretta et al., 2017). While the decline 

has been driven by the population 

segment in the northwestern Hawaiian 

Islands, the number of documented 

sightings and annual births in the main 

Hawaiian Islands has increased since 

the mid-1990s (Baker, 2004; Baker et al., 

2016). In the main Hawaiian Islands, the 

estimated population growth rate is 6.5 

percent per year (Baker et al., 2011; 

Carretta et al., 2017). Of note, in the 

2013 HRC Monitoring Report, tagged 

monk seals did not show any behavioral 

changes during periods of MFAS. 

Generally speaking, most pinniped 

stocks in the HSTT Study Area are 

thought to be stable or increasing. In 

summary and as described above, the 

following factors primarily support our 

preliminary determination that the 

impacts resulting from the Navy’s 

activities are not expected to adversely 

affect pinnipeds taken through effects 

on annual rates of recruitment or 

survival. 

• As described in the ‘‘Serious Injury 

or Mortality’’ section (Table 68), 0.8 

mortalities annually over five years is 

proposed for authorization for California 

sea lions. The proposed mortality for 

California falls below the insignificance 

threshold and, therefore, we consider 

the addition an insignificant 

incremental increase to human-caused 

mortality. No mortalities of other 

pinnipeds are proposed for 

authorization or anticipated to occur. 

• As described above, any PTS that 

may occur is expected to be of a 

relatively smaller degree because of the 

unlikelihood that animals would be 

close enough for a long enough amount 

of time to incur more severe PTS (for 

sonar) and the anticipated effectiveness 

of mitigation in preventing very close 

exposures for explosives. 

• While the majority of takes are 

caused by exposure during ASW 

activities, the impacts from these 

exposures are not expected to have 

either significant or long-term effects 

because (and as discussed above): 

Æ ASW activities typically involve 

fast-moving assets (relative to marine 

mammals swim speeds) and individuals 

are not expected to be exposed either for 

long periods within a day or over many 

sequential days. 


sradovich on DSK3GMQ082PROD with PROPOSALS2
30020 Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 

Æ As discussed, the majority of the 

harassment takes result from hullmounted sonar during MTEs. When 

distance cutoffs are applied for 

pinnipeds, this means that all of the 

takes from hull-mounted sonar (MF1) 

result from above exposure 160 dB. 

However, the majority (e.g., 83 percent) 

of the takes results from exposures 

below 172 dB. The majority of the takes 

have a relatively lower likelihood in 

have severe impacts. 

• As described in detail above (Tables 

80 and 81), the scale of the effects are 

such that pinnipeds are taken an 

average of less than 2 days per year. 

While some individuals of California 

sea lions, Northern fur seal, and harbor 

seals that might remain in the Navy 

SOCAL action area for extended periods 

of time could be taken on more, 17 to 

29 days per year. These behavioral takes 

are not all expected to be of particularly 

high intensity and nor are they likely to 

occur over sequential days, which 

suggests that the overall scale of impacts 

for any individual would be relatively 

low. Some California sea lion 

individuals in SOCAL may occasionally 

be taken in sequential days, because of 

the nature of the exposures and the 

other factors discussed above, any 

impacts to individual fitness would be 

limited and with the potential to accrue 

to no more than a limited number of 

individuals and would not be expected 

to affect rates of recruitment or survival. 

We further note that California sea lions 

have an increasing population trend. 

• The HSTT activities are expected to 

occur in an area/time of specific 

importance for reproductive, feeding, or 

other known critical behaviors for 

pinnipeds, particularly in critical 

habitat for ESA-listed Hawaiian monk 

seal; however, Navy’s activities are not 

anticipated to affect critical habitat. 

Populations are increasing for monk 

seals on the main Hawaiian islands. 

• Pinnipeds found in the HSTT Study 

Area are not depleted under the MMPA, 

nor are they listed under the ESA with 

the exception of the Hawaiian monk 

seal and Guadalupe fur seal which are 

listed as endangered under the ESA and 

depleted under the MMPA. 

Consequently, the activities are not 

expected to adversely impact rates of 

recruitment or survival of any of the 

analyzed stocks of pinnipeds (Table 77 

above in this section). 

Preliminary Determination 

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 Specified Activities will have a 

negligible impact on all affected marine 

mammal species or stocks. 

Subsistence Harvest of Marine 

Mammals 

There are no relevant subsistence uses 

of marine mammals implicated by this 

action. Therefore, NMFS has 

preliminarily determined that the total 

taking affecting 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 

There are nine marine mammal 

species under NMFS jurisdiction that 

are listed as endangered or threatened 

under the ESA with confirmed or 

possible occurrence in the Study Area: 

Blue whale (Eastern and Central North 

Pacific stocks), fin whale (CA/OR/WA 

and Hawaiian stocks), gray whale 

(Western North Pacific stock), 

humpback whale (Mexico and Central 

America DPSs), sei whale (Eastern 

North Pacific and Hawaiian stocks), 

sperm whale (CA/OR/WA and Hawaiian 

stocks), false killer whale (Main 

Hawaiian Islands Insular), Hawaiian 

monk seal (Hawaiian stock), and 

Guadalupe fur seal (Mexico to 

California). There is also critical habitat 

designated for Hawaiian monk seal and 

proposed critical habitat for Main 

Hawaiian Island insular false killer 

whales. The Navy will consult with 

NMFS pursuant to section 7 of the ESA, 

and NMFS will also consult internally 

on the issuance of LOAs under section 

101(a)(5)(A) of the MMPA for HSTT 

activities. Consultation will be 

concluded prior to a determination on 

the issuance of the final rule and LOAs. 

National Marine Sanctuaries Act 

NMFS will work with NOAA’s Office 

of National Marine Sanctuaries to fulfill 

our responsibilities under the NMSA as 

warranted and will complete any NMSA 

requirements prior to a determination 

on the issuance of the final rule and 

LOAs. 

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 its 

Specified Activities (i.e., the issuance of 

an incidental take authorization) with 

respect to potential impacts on the 

human environment. 

Accordingly, NMFS plans to adopt 

the Navy’s EIS/OEIS for the HSTT Study 

Area provided our independent 

evaluation of the document finds that it 

includes adequate information 

analyzing the effects on the human 

environment of issuing regulations and 

LOAs. NMFS is a cooperating agency on 

the Navy’s HSTT DEIS/OEIS and has 

worked extensively with the Navy in 

developing the document. 

The Navy’s HSTT DEIS/OEIS was 

made available for public comment at 

https://hstteis.com/ on October 13, 

2017. 

We will review all comments 

submitted in response to this notice 

prior to concluding our NEPA process 

or making a final decision on the final 

rule and LOA requests. 

Classification 

The Office of Management and Budget 

has determined that this proposed rule 

is not significant for purposes of 

Executive Order 12866. 

Pursuant to the Regulatory Flexibility 

Act (RFA), the Chief Counsel for 

Regulation of the Department of 

Commerce has certified to the Chief 

Counsel for Advocacy of the Small 

Business Administration that this 

proposed rule, if adopted, would not 

have a significant economic impact on 

a substantial number of small entities. 

The RFA requires Federal agencies to 

prepare an analysis of a rule’s impact on 

small entities whenever the agency is 

required to publish a notice of proposed 

rulemaking. However, a Federal agency 

may certify, pursuant to 5 U.S.C. 605(b), 

that the action will not have a 

significant economic impact on a 

substantial number of small entities. 

The Navy is the sole entity that would 

be affected by this rulemaking, and the 

Navy is not a small governmental 

jurisdiction, small organization, or small 

business, as defined by the RFA. Any 

requirements imposed by an LOA 

issued pursuant to these regulations, 

and any monitoring or reporting 

requirements imposed by these 

regulations, would be applicable only to 

the Navy. NMFS does not expect the 

issuance of these regulations or the 

associated LOA to result in any impacts 

to small entities pursuant to the RFA. 

Because this action, if adopted, would 

directly affect the Navy and not a small 

entity, NMFS concludes the action 

would not result in a significant 

economic impact on a substantial 

number of small entities. 

List of Subjects in 50 CFR Part 218 

Exports, Fish, Imports, Incidental 

take, Indians, Labeling, Marine 

mammals, Navy, Penalties, Reporting 


sradovich on DSK3GMQ082PROD with PROPOSALS2
Federal Register / Vol. 83, No. 123 / Tuesday, June 26, 2018 / Proposed Rules 30021 

and recordkeeping requirements, 

Seafood, Sonar, Transportation. 

Dated: June 14, 2018. 

Samuel D. Rauch III, 

Deputy Assistant Administrator for 

Regulatory Programs, National Marine 

Fisheries Service. 

PART 218—REGULATIONS 

GOVERNING THE TAKING AND 

IMPORTING OF MARINE MAMMALS 

■ 1. The authority citation for part 218 

continues to read as follows: 

Authority: 16 U.S.C. 1361 et seq. 

■ 2. Revise subpart H to part 218 to read 

as follows: 

Sec. 

218.70 Specified activity and specified 

geographical region. 

218.71 Effective dates. 

218.72 Permissible methods of taking. 

218.73 Prohibitions. 

218.74 Mitigation requirements. 

218.75 Requirements for monitoring and 

reporting. 

218.76 Letters of Authorization. 

218.77 Renewals and modifications of 

Letters of Authorization 

218.78 [Reserved] 

218.79 [Reserved] 

Subpart H—Taking and Importing 

Marine Mammals; U.S. Navy’s HawaiiSouthern California Training and 

Testing (HSTT) 

§ 218.70 Specified activity and specified 

geographical region. 

(a) Regulations in this subpart apply 

only to the U.S. Navy for the taking of 

marine mammals that occurs in the area 

outlined in paragraph (b) of this section 

and that occurs incidental to the 

activities described in paragraph (c) of 

this section. 

(b) The taking of marine mammals by 

the Navy may be authorized in Letters 

of Authorization (LOAs) only if it occurs 

within the Hawaii-Southern California 

Training and Testing (HSTT) Study 

Area, which includes established 

operating and warning areas across the 

north-central Pacific Ocean, from the 

mean high tide line in Southern 

California west to Hawaii and the 

International Date Line. The Study Area 

includes the at-sea areas of three 

existing range complexes (the Hawaii 

Range Complex (HRC), the Southern 

California Range Complex (SOCAL), and 

the Silver Strand Training Complex, and 

overlaps a portion of the Point Mugu 

Sea Range (PMSR)). Also included in 

the Study Area are Navy pierside 

locations in Hawaii and Southern 

California, Pearl Harbor, San Diego Bay, 

and the transit corridor on the high seas 

where sonar training and testing may 

occur. 

(c) The taking of marine mammals by 

the Navy is only authorized if it occurs 

incidental to the Navy’s conducting 

training and testing activities. The 

Navy’s use of sonar and other 

transducers, in-water detonations, air 

guns, pile driving/extraction, and vessel 

movements incidental to training and 

testing exercises may cause take by 

harassment, serious injury or mortality 

as defined by the MMPA through the 

various warfare mission areas in which 

the Navy would conduct including 

amphibious warfare, anti-submarine 

warfare, expeditionary warfare, surface 

warfare, mine warfare, and other 

activities (sonar and other transducers, 

pile driving and removal activities, air 

guns, vessel strike). 

§ 218.71 Effective dates. 

Regulations in this subpart are 

effective [date 30 days after date of 

publication of the final rule in the 

Federal Register] through [date 5 

years and 30 days after date of 

publication of the final rule in the 

Federal Register]. 

§ 218.72 Permissible methods of taking. 

Under LOAs issued pursuant to 

§ 216.106 of this chapter and § 218.77, 

the Holder of the LOAs (hereinafter 

‘‘Navy’’) may incidentally, but not 

intentionally, take marine mammals 

within the area described in § 218.70(b) 

by Level A harassment and Level B 

harassment associated with the use of 

active sonar and other acoustic sources 

and explosives as well as serious injury 

or mortality associated with vessel 

strikes provided the activity is in 

compliance with all terms, conditions, 

and requirements of these regulations in 

this subpart and the applicable LOAs. 

§ 218.73 Prohibitions. 

Notwithstanding takings 

contemplated in § 218.72 and 

authorized by LOAs issued under 

§ 216.106 of this chapter and § 218.76, 

no person in connection with the 

activities described in § 218.72 may: 

(a) Violate, or fail to comply with, the 

terms, conditions, and requirements of 

this subpart or an LOA issued under 

§ 216.106 of this chapter and § 218.76; 

(b) Take any marine mammal not 

specified in such LOAs; 

(c) Take any marine mammal 

specified in such LOAs in any manner 

other than as specified; 

(d) Take a marine mammal specified 

in such LOAs if NMFS determines such 

taking results in more than a negligible 

impact on the species or stocks of such 

marine mammal; or or 

(e) Take a marine mammal specified 

in such LOAs if NMFS determines such 

taking results in an unmitigable adverse 

impact on the species or stock of such 

marine mammal for taking for 

subsistence uses. 

§ 218.74 Mitigation requirements. 

When conducting the activities 

identified in § 218.70(c), the mitigation 

measures contained in any LOAs issued 

under § 216.106 of this chapter and 

§ 218.76 must be implemented. These 

mitigation measures shall include the 

following requirements, but are not 

limited to: 

(a) Procedural Mitigation. Procedural 

mitigation is mitigation that the Navy 

shall implement whenever and 

wherever an applicable training or 

testing activity takes place within the 

HSTT Study Area for each applicable 

activity category or stressor category and 

includes acoustic stressors (i.e., active 

sonar, air guns, pile driving, weapons 

firing noise), explosive stressors (i.e., 

sonobuoys, torpedoes, medium-caliber 

and large-caliber projectiles, missiles 

and rockets, bombs, sinking exercises, 

mines, anti-swimmer grenades, and mat 

weave and obstacle loading), and 

physical disturbance and strike stressors 

(i.e., vessel movement, towed in-water 

devices, small-, medium-, and largecaliber non-explosive practice 

munitions, non-explosive missiles and 

rockets, non-explosive bombs and mine 

shapes). 

(1) Environmental Awareness and 

Education. Appropriate personnel 

involved in mitigation and training or 

testing activity reporting under the 

Specified Activities shall complete one 

or more modules of the U.S Navy Afloat 

Environmental Compliance Training 

Series, as identified in their career path 

training plan. Modules include: 

Introduction to the U.S. Navy Afloat 

Environmental Compliance Training 

Series, Marine Species Awareness 

Training, U.S. Navy Protective Measures 

Assessment Protocol, and U.S. Navy 

Sonar Positional Reporting System and 

Marine Mammal Incident Reporting. 

Additionally, to increase the 

environmental awareness of naval assets 

operating in designated areas to the 

potential seasonal presence of 

concentrations of large whales, 

including humpback whales, gray 

whales, blue whales, and fin whales, the 

Navy will issue seasonal awareness 

notification messages. These messages 

include: 

(i) Humpback Whale Awareness 

Notification Message Area (November 

15–April 15). The Navy shall issue a 

seasonal awareness notification message 

to alert ships and aircraft operating in 

the area to the possible presence of 

concentrations of large whales, 


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including humpback whales. To 

maintain safety of navigation and to 

avoid interactions with large whales 

during transits, the Navy shall instruct 

vessels to remain vigilant to the 

presence of large whale species 

(including humpback whales), that 

when concentrated seasonally, may 

become vulnerable to vessel strikes. 

Lookouts shall use the information from 

the awareness notification message to 

assist their visual observation of 

applicable mitigation zones during 

training and testing activities and to aid 

in the implementation of procedural 

mitigation. 

(ii) Blue Whale Awareness 

Notification Message Area (June 1– 

October 31). The Navy shall issue a 

seasonal awareness notification message 

to alert ships and aircraft operating in 

the area to the possible presence of 

concentrations of large whales, 

including blue whales. To maintain 

safety of navigation and to avoid 

interactions with large whales during 

transits, the Navy shall instruct vessels 

to remain vigilant to the presence of 

large whale species (including blue 

whales), that when concentrated 

seasonally, may become vulnerable to 

vessel strikes. Lookouts shall use the 

information from the awareness 

notification messages to assist their 

visual observation of applicable 

mitigation zones during training and 

testing activities and to aid in the 

implementation of procedural 

mitigation observation of applicable 

mitigation zones during training and 

testing activities and to aid in the 

implementation of procedural 

mitigation. 

(iii) Gray Whale Awareness 

Notification Message Area (November 

1–March 31). The Navy shall issue a 

seasonal awareness notification message 

to alert ships and aircraft operating in 

the area to the possible presence of 

concentrations of large whales, 

including gray whales. To maintain 

safety of navigation and to avoid 

interactions with large whales during 

transits, the Navy shall instruct vessels 

to remain vigilant to the presence of 

large whale species (including gray 

whales), that when concentrated 

seasonally, may become vulnerable to 

vessel strikes. Lookouts shall use the 

information from the awareness 

notification messages to assist their 

visual observation of applicable 

mitigation zones during training and 

testing activities and to aid in the 

implementation of procedural 

mitigation. 

(iv) Fin Whale Awareness Notification 

Message Area (November 1–May 31). 

The Navy shall issue a seasonal 

awareness notification message to alert 

ships and aircraft operating in the area 

to the possible presence of 

concentrations of large whales, 

including fin whales. To maintain safety 

of navigation and to avoid interactions 

with large whales during transits, the 

Navy shall instruct vessels to remain 

vigilant to the presence of large whale 

species (including fin whales), that 

when concentrated seasonally, may 

become vulnerable to vessel strikes. 

Lookouts shall use the information from 

the awareness notification messages to 

assist their visual observation of 

applicable mitigation zones during 

training and testing activities and to aid 

in implementation of procedural 

mitigation. 

(2) Active Sonar. Active sonar 

includes low-frequency active sonar, 

mid-frequency active sonar, and highfrequency active sonar. For vessel-based 

active sonar activities, mitigation 

applies only to sources that are 

positively controlled and deployed from 

manned surface vessels (e.g., sonar 

sources towed from manned surface 

platforms). For aircraft-based active 

sonar activities, mitigation applies to 

sources that are positively controlled 

and deployed from manned aircraft that 

do not operate at high altitudes (e.g., 

rotary-wing aircraft). Mitigation does 

not apply to active sonar sources 

deployed from unmanned aircraft or 

aircraft operating at high altitudes (e.g., 

maritime patrol aircraft). 

(i) Number of Lookouts and 

Observation Platform—(A) Hullmounted sources: Two lookouts at the 

forward part of the ship for platforms 

without space or manning restrictions 

while underway; One lookout at the 

forward part of a small boat or ship for 

platforms with space or manning 

restrictions while underway; and One 

lookout for platforms using active sonar 

while moored or at anchor (including 

pierside). 

(B) Non-hull mounted sources: One 

lookout on the ship or aircraft 

conducting the activity. 

(ii) Mitigation Zone and 

Requirements—(A) Prior to the start of 

the activity the Navy shall observe for 

floating vegetation and marine 

mammals; if resource is observed, the 

Navy shall not commence use of active 

sonar. 

(B) During low-frequency active sonar 

at or above 200 decibel (dB) and hullmounted mid-frequency active sonar the 

Navy shall observe for marine mammals 

and power down active sonar 

transmission by 6 dB if resource is 

observed within 1,000 yards (yd) of the 

sonar source; power down by an 

additional 4 dB (10 dB total) if resource 

is observed within 500 yd of the sonar 

source; and cease transmission if 

resource is observed within 200 yd of 

the sonar source. 

(C) During low-frequency active sonar 

below 200 dB, mid-frequency active 

sonar sources that are not hull mounted, 

and high-frequency active sonar the 

Navy shall observe for marine mammals 

and cease active sonar transmission if 

resource is observed within 200 yd of 

the sonar source. 

(D) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence active 

sonar transmission until one of the 

recommencement conditions has been 

met: The animal is observed exiting the 

mitigation zone; the animal is thought to 

have exited the mitigation zone based 

on a determination of its course, speed, 

and movement relative to the sonar 

source; the mitigation zone has been 

clear from any additional sightings for 

10 min for aircraft-deployed sonar 

sources or 30 min for vessel-deployed 

sonar sources; for mobile activities, the 

active sonar source has transited a 

distance equal to double that of the 

mitigation zone size beyond the location 

of the last sighting; or for activities 

using hull-mounted sonar, the lookout 

concludes that dolphins are deliberately 

closing in on the ship to ride the ship’s 

bow wave, and are therefore out of the 

main transmission axis of the sonar (and 

there are no other marine mammal 

sightings within the mitigation zone). 

(3) Air Guns. (i) Number of Lookouts 

and Observation Platform—One lookout 

positioned on a ship or pierside. 

(ii) Mitigation Zone and 

Requirements—150 yd around the air 

gun. 

(A) Prior to the start of the activity 

(e.g., when maneuvering on station), the 

Navy shall observe for floating 

vegetation, and marine mammals; if 

resource is observed, the Navy shall not 

commence use of air guns. 

(B) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease use of 

air guns. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence the use 

of air guns until one of the 

recommencement conditions has been 

met: The animal is observed exiting the 

mitigation zone; the animal is thought to 

have exited the mitigation zone based 

on a determination of its course, speed, 

and movement relative to the air gun; 

the mitigation zone has been clear from 

any additional sightings for 30 min; or 

for mobile activities, the air gun has 

transited a distance equal to double that 


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of the mitigation zone size beyond the 

location of the last sighting. 

(4) Pile Driving. Pile driving and pile 

extraction sound during Elevated 

Causeway System training. 

(i) Number of Lookouts and 

Observation Platform—One lookout 

positioned on the shore, the elevated 

causeway, or a small boat. 

(ii) Mitigation Zone and 

Requirements—100 yd around the pile 

driver. 

(A) Thirty minutes prior to the start of 

the activity, the Navy shall observe for 

floating vegetation and marine 

mammals; if resource is observed, the 

Navy shall not commence impact pile 

driving or vibratory pile extraction. 

(B) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease impact 

pile driving or vibratory pile extraction. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence pile 

driving until one of the 

recommencement conditions has been 

met: The animal is observed exiting the 

mitigation zone; the animal is thought to 

have exited the mitigation zone based 

on a determination of its course, speed, 

and movement relative to the pile 

driving location; or the mitigation zone 

has been clear from any additional 

sightings for 30 min. 

(5) Weapons Firing Noise. Weapons 

firing noise associated with large-caliber 

gunnery activities. 

(i) Number of Lookouts and 

Observation Platform—One lookout 

shall be positioned on the ship 

conducting the firing. Depending on the 

activity, the lookout could be the same 

as the one described in Explosive 

Medium-Caliber and Large-Caliber 

Projectiles or in Small-, Medium-and 

Large-Caliber Non-Explosive Practice 

Munitions. 

(ii) Mitigation Zone and 

Requirements—Thirty degrees on either 

side of the firing line out to 70 yd from 

the muzzle of the weapon being fired. 

(A) Prior to the start of the activity, 

the Navy shall observe for floating 

vegetation, and marine mammals; if 

resource is observed, the Navy shall not 

commence weapons firing. 

(B) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease 

weapons firing. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence 

weapons firing until one of the 

recommencement conditions has been 

met: The animal is observed exiting the 

mitigation zone; the animal is thought to 

have exited the mitigation zone based 

on a determination of its course, speed, 

and movement relative to the firing 

ship; the mitigation zone has been clear 

from any additional sightings for 30 

min; or for mobile activities, the firing 

ship has transited a distance equal to 

double that of the mitigation zone size 

beyond the location of the last sighting. 

(6) Explosive Sonobuoys. (i) Number 

of Lookouts and Observation Platform— 

One lookout positioned in an aircraft or 

on small boat. 

(ii) Mitigation Zone and 

Requirements—600 yd around an 

explosive sonobuoy. 

(A) Prior to the start of the activity 

(e.g., during deployment of a sonobuoy 

field, which typically lasts 20–30 min), 

the Navy shall conduct passive acoustic 

monitoring for marine mammals, and 

observe for floating vegetation and 

marine mammals; if resource is visually 

observed, the Navy shall not commence 

sonobuoy or source/receiver pair 

detonations. 

(B) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease 

sonobuoy or source/receiver pair 

detonations. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence the use 

of explosive sonobuoys until one of the 

recommencement conditions has been 

met: The animal is observed exiting the 

mitigation zone; the animal is thought to 

have exited the mitigation zone based 

on a determination of its course, speed, 

and movement relative to the sonobuoy; 

or the mitigation zone has been clear 

from any additional sightings for 10 min 

when the activity involves aircraft that 

have fuel constraints, or 30 min when 

the activity involves aircraft that are not 

typically fuel constrained. 

(7) Explosive Torpedoes. (i) Number 

of Lookouts and Observation Platform— 

One lookout positioned in an aircraft. 

(ii) Mitigation Zone and 

Requirements—2,100 yd around the 

intended impact location. 

(A) Prior to the start of the activity 

(e.g., during deployment of the target), 

the Navy shall conduct passive acoustic 

monitoring for marine mammals, and 

observe for floating vegetation, jellyfish 

aggregations, and marine mammals; if 

resource is visually observed, the Navy 

shall not commence firing. 

(B) During the activity, the Navy shall 

observe for marine mammals and 

jellyfish aggregations; if resource is 

observed, the Navy shall cease firing. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence firing 

until one of the recommencement 

conditions has been met: The animal is 

observed exiting the mitigation zone; 

the animal is thought to have exited the 

mitigation zone based on a 

determination of its course, speed, and 

movement relative to the intended 

impact location; or the mitigation zone 

has been clear from any additional 

sightings for 10 min when the activity 

involves aircraft that have fuel 

constraints, or 30 min when the activity 

involves aircraft that are not typically 

fuel constrained. After completion of 

the activity, the Navy shall observe for 

marine mammals; if any injured or dead 

resources are observed, the Navy shall 

follow established incident reporting 

procedures. 

(8) Explosive Medium-Caliber and 

Large-Caliber Projectiles. Gunnery 

activities using explosive mediumcaliber and large-caliber projectiles. 

Mitigation applies to activities using a 

surface target. 

(i) Number of Lookouts and 

Observation Platform—One Lookout on 

the vessel or aircraft conducting the 

activity. For activities using explosive 

large-caliber projectiles, depending on 

the activity, the Lookout could be the 

same as the one described in Weapons 

Firing Noise in paragraph (a)(5)(i) of this 

section. 

(ii) Mitigation Zone and 

Requirements—(A) 200 yd around the 

intended impact location for air-tosurface activities using explosive 

medium-caliber projectiles, 

(B) 600 yd around the intended 

impact location for surface-to-surface 

activities using explosive mediumcaliber projectiles, or 

(C) 1,000 yd around the intended 

impact location for surface-to-surface 

activities using explosive large-caliber 

projectiles. 

(D) Prior to the start of the activity 

(e.g., when maneuvering on station), the 

Navy shall observe for floating 

vegetation and marine mammals; if 

resource is observed, the Navy shall not 

commence firing. 

(E) During the activity, observe for 

marine mammals; if resource is 

observed, the Navy shall cease firing. 

(F) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence firing 

until one of the recommencement 

conditions has been met: The animal is 

observed exiting the mitigation zone; 

the animal is thought to have exited the 

mitigation zone based on a 

determination of its course, speed, and 

movement relative to the intended 

impact location; the mitigation zone has 

been clear from any additional sightings 

for 10 min for aircraft-based firing or 30 

min for vessel-based firing; or for 

activities using mobile targets, the 


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intended impact location has transited a 

distance equal to double that of the 

mitigation zone size beyond the location 

of the last sighting. 

(9) Explosive Missiles and Rockets. 

Aircraft-deployed explosive missiles 

and rockets. Mitigation applies to 

activities using a surface target. 

(i) Number of Lookouts and 

Observation Platform—One lookout 

positioned in an aircraft. 

(ii) Mitigation Zone and 

Requirements—(A) 900 yd around the 

intended impact location for missiles or 

rockets with 0.6–20 lb net explosive 

weight, or 

(B) 2,000 yd around the intended 

impact location for missiles with 21– 

500 lb net explosive weight. 

(C) Prior to the start of the activity 

(e.g., during a fly-over of the mitigation 

zone), the Navy shall observe for 

floating vegetation and marine 

mammals; if resource is observed, the 

Navy shall not commence firing. 

(D) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease firing. 

(E) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence firing 

until one of the recommencement 

conditions has been met: The animal is 

observed exiting the mitigation zone; 

the animal is thought to have exited the 

mitigation zone based on a 

determination of its course, speed, and 

movement relative to the intended 

impact location; or the mitigation zone 

has been clear from any additional 

sightings for 10 min when the activity 

involves aircraft that have fuel 

constraints, or 30 min when the activity 

involves aircraft that are not typically 

fuel constrained. 

(10) Explosive Bombs. (i) Number of 

Lookouts and Observation Platform— 

One lookout positioned in an aircraft 

conducting the activity. 

(ii) Mitigation Zone and 

Requirements—2,500 yd around the 

intended target. 

(A) Prior to the start of the activity 

(e.g., when arriving on station), the 

Navy shall observe for floating 

vegetation and marine mammals; if 

resource is observed, the Navy shall not 

commence bomb deployment. 

(B) During target approach, the Navy 

shall observe for marine mammals; if 

resource is observed, the Navy shall 

cease bomb deployment. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence bomb 

deployment until one of the 

recommencement conditions has been 

met: The animal is observed exiting the 

mitigation zone; the animal is thought to 

have exited the mitigation zone based 

on a determination of its course, speed, 

and movement relative to the intended 

target; the mitigation zone has been 

clear from any additional sightings for 

10 min; or for activities using mobile 

targets, the intended target has transited 

a distance equal to double that of the 

mitigation zone size beyond the location 

of the last sighting. 

(11) Sinking Exercises. (i) Number of 

Lookouts and Observation Platform— 

Two lookouts (one positioned in an 

aircraft and one on a vessel). 

(ii) Mitigation Zone and 

Requirements—2.5 nmi around the 

target ship hulk. 

(A) 90 min prior to the first firing, the 

Navy shall conduct aerial observations 

for floating vegetation, jellyfish 

aggregations, and marine mammals; if 

resource is observed, the Navy shall not 

commence firing. 

(B) During the activity, the Navy shall 

conduct passive acoustic monitoring 

and visually observe for marine 

mammals from the vessel; if resource is 

visually observed, the Navy shall cease 

firing. 

(C) Immediately after any planned or 

unplanned breaks in weapons firing of 

longer than 2 hrs, the Navy shall 

observe for marine mammals from the 

aircraft and vessel; if resource is 

observed, the Navy shall not commence 

firing. 

(D) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence firing 

until one of the recommencement 

conditions has been met: The animal is 

observed exiting the mitigation zone; 

the animal is thought to have exited the 

mitigation zone based on a 

determination of its course, speed, and 

movement relative to the target ship 

hulk; or the mitigation zone has been 

clear from any additional sightings for 

30 min. 

(E) For 2 hrs after sinking the vessel 

(or until sunset, whichever comes first), 

the Navy shall observe for marine 

mammals; if any injured or dead 

resources are observed, the Navy shall 

follow established incident reporting 

procedures. 

(12) Explosive Mine Countermeasure 

and Neutralization Activities. 

(i) Number of Lookouts and 

Observation Platform—(A) One lookout 

positioned on a vessel or in an aircraft 

when using up to 0.1–5 lb net explosive 

weight charges. 

(B) Two lookouts (one in an aircraft 

and one on a small boat) when using up 

to 6–650 lb net explosive weight 

charges. 

(ii) Mitigation Zone and 

Requirements—(A) 600 yd around the 

detonation site for activities using 0.1– 

5 lb net explosive weight, or 

(B) 2,100 yd around the detonation 

site for activities using 6–650 lb net 

explosive weight (including high 

explosive target mines). 

(C) Prior to the start of the activity 

(e.g., when maneuvering on station; 

typically, 10 min when the activity 

involves aircraft that have fuel 

constraints, or 30 min when the activity 

involves aircraft that are not typically 

fuel constrained), the Navy shall 

observe for floating vegetation and 

marine mammals; if resource is 

observed, the Navy shall not commence 

detonations. 

(D) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease 

detonations. 

(E) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence 

detonations until one of the 

recommencement conditions has been 

met: The animal is observed exiting the 

mitigation zone; the animal is thought to 

have exited the mitigation zone based 

on a determination of its course, speed, 

and movement relative to detonation 

site; or the mitigation zone has been 

clear from any additional sightings for 

10 min when the activity involves 

aircraft that have fuel constraints, or 30 

min when the activity involves aircraft 

that are not typically fuel constrained. 

(F) After completion of the activity, 

the Navy shall observe for marine 

mammals and sea turtles (typically 10 

min when the activity involves aircraft 

that have fuel constraints, or 30 min. 

when the activity involves aircraft that 

are not typically fuel constrained); if 

any injured or dead resources are 

observed, the Navy shall follow 

established incident reporting 

procedures. 

(13) Explosive Mine Neutralization 

Activities Involving Navy Divers. 

(i) Number of Lookouts and 

Observation Platform—(A) Two 

lookouts (two small boats with one 

Lookout each, or one Lookout on a small 

boat and one in a rotary-wing aircraft) 

when implementing the smaller 

mitigation zone. 

(B) Four lookouts (two small boats 

with two Lookouts each), and a pilot or 

member of an aircrew shall serve as an 

additional Lookout if aircraft are used 

during the activity, when implementing 

the larger mitigation zone. 

(ii) Mitigation Zone and 

Requirements—(A) The Navy shall not 

set time-delay firing devices (0.1–29 lb 

net explosive weight) to exceed 10 min. 


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(B) 500 yd around the detonation site 

during activities under positive control 

using 0.1–20 lb net explosive weight, or 

(C) 1,000 yd around the detonation 

site during all activities using timedelay fuses (0.1–29 lb net explosive 

weight) and during activities under 

positive control using 21–60 lb net 

explosive weight charges. 

(D) Prior to the start of the activity 

(e.g., when maneuvering on station for 

activities under positive control; 30 min 

for activities using time-delay firing 

devices), the Navy shall observe for 

floating vegetation and marine 

mammals; if resource is observed, the 

Navy shall not commence detonations 

or fuse initiation. 

(E) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease 

detonations or fuse initiation. All divers 

placing the charges on mines shall 

support the Lookouts while performing 

their regular duties and shall report all 

marine mammal sightings to their 

supporting small boat or Range Safety 

Officer. To the maximum extent 

practicable depending on mission 

requirements, safety, and environmental 

conditions, boats shall position 

themselves near the mid-point of the 

mitigation zone radius (but outside of 

the detonation plume and human safety 

zone), shall position themselves on 

opposite sides of the detonation location 

(when two boats are used), and shall 

travel in a circular pattern around the 

detonation location with one Lookout 

observing inward toward the detonation 

site and the other observing outward 

toward the perimeter of the mitigation 

zone. If used, aircraft shall travel in a 

circular pattern around the detonation 

location to the maximum extent 

practicable. 

(F) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence 

detonations or fuse initiation until one 

of the recommencement conditions has 

been met: The animal is observed 

exiting the mitigation zone; the animal 

is thought to have exited the mitigation 

zone based on a determination of its 

course, speed, and movement relative to 

the detonation site; or the mitigation 

zone has been clear from any additional 

sightings for 10 min during activities 

under positive control with aircraft that 

have fuel constraints, or 30 min during 

activities under positive control with 

aircraft that are not typically fuel 

constrained and during activities using 

time-delay firing devices. 

(G) After completion of an activity 

using time-delay firing devices, the 

Navy shall observe for marine mammals 

for 30 min; if any injured or dead 

resources are observed, the Navy follow 

established incident reporting 

procedures. 

(14) Maritime Security Operations— 

Anti-Swimmer Grenades. (i) Number of 

Lookouts and Observation Platform— 

One lookout positioned on the small 

boat conducting the activity. 

(ii) Mitigation Zone and 

Requirements—200 yd around the 

intended detonation location. 

(A) Prior to the start of the activity 

(e.g., when maneuvering on station), the 

Navy shall observe for floating 

vegetation and marine mammals; if 

resource is observed, the Navy shall not 

commence detonations. 

(B) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease 

detonations. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence 

detonations until one of the 

recommencement conditions has been 

met: The animal is observed exiting the 

mitigation zone; the animal is thought to 

have exited the mitigation zone based 

on a determination of its course, speed, 

and movement relative to the intended 

detonation location; the mitigation zone 

has been clear from any additional 

sightings for 30 min; or the intended 

detonation location has transited a 

distance equal to double that of the 

mitigation zone size beyond the location 

of the last sighting. 

(15) Under Demolition Multiple 

Charge—Mat Weave and Obstacle 

Loading. (i) Number of Lookouts and 

Observation Platform—Two Lookouts 

(one positioned on a small boat and one 

positioned on shore from an elevated 

platform). 

(ii) Mitigation Zone and 

Requirements—700 yd around the 

intended detonation site. 

(A) For 30 min prior to the first 

detonation, the Lookout positioned on a 

small boat shall observe for floating 

vegetation and marine mammals; if 

resource is observed, the Navy shall not 

commence the initial detonation. 

(B) For 10 min prior to the first 

detonation, the Lookout positioned on 

shore shall use binoculars to observe for 

marine mammals; if resource is 

observed, the Navy shall not commence 

the initial detonation until the 

mitigation zone has been clear of any 

additional sightings for a minimum of 

10 min. 

(C) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease 

detonations. 

(D) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence 

detonations until one of the 

recommencement conditions has been 

met: The animal is observed exiting the 

mitigation zone; the animal is thought to 

have exited the mitigation zone based 

on a determination of its course, speed, 

and movement relative to the detonation 

site; or the mitigation zone has been 

clear from any additional sightings for 

10 min (as determined by the shore 

observer). 

(E) After completion of the activity, 

the Lookout positioned on a small boat 

shall observe for marine mammals for 

30 min; if any injured or dead resources 

are observed, the Navy shall follow 

established incident reporting 

procedures. 

(16) Vessel Movement. The mitigation 

shall not be applied if: The vessel’s 

safety is threatened; the vessel is 

restricted in its ability to maneuver (e.g., 

during launching and recovery of 

aircraft or landing craft, during towing 

activities, when mooring, etc.); the 

vessel is operated autonomously; or 

when impracticable based on mission 

requirements (e.g., during Amphibious 

Assault—Battalion Landing exercise). 

(i) Number of Lookouts and 

Observation Platform—One lookout on 

the vessel that is underway. 

(ii) Mitigation Zone and 

Requirements—(A) 500 yd around 

whales—When underway, the Navy 

shall observe for marine mammals; if a 

whale is observed, the Navy shall 

maneuver to maintain distance. 

(B) 200 yd around all other marine 

mammals (except bow-riding dolphins 

and pinnipeds hauled out on man-made 

navigational structures, port structures, 

and vessels)—When underway, the 

Navy shall observe for marine 

mammals; if a marine mammal other 

than a whale, bow-riding dolphin, or 

hauled-out pinniped is observed, the 

Navy shall maneuver to maintain 

distance. 

(17) Towed In-water Devices. 

Mitigation applies to devices that are 

towed from a manned surface platform 

or manned aircraft. The mitigation shall 

not be applied if the safety of the towing 

platform or in-water device is 

threatened. 

(i) Number of Lookouts and 

Observation Platform—One lookout 

positioned on a manned towing 

platform. 

(ii) Mitigation Zone and 

Requirements—250 yd around marine 

mammals. When towing an in-water 

device, the Navy shall observe for 

marine mammals; if resource is 

observed, the Navy shall maneuver to 

maintain distance. 


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(18) Small-, Medium-, and LargeCaliber Non-Explosive Practice 

Munitions. Mitigation applies to 

activities using a surface target. 

(i) Number of Lookouts and 

Observation Platform—One Lookout 

positioned on the platform conducting 

the activity. Depending on the activity, 

the Lookout could be the same as the 

one described for Weapons Firing Noise 

in paragraph (a)(5)(i) of this section. 

(ii) Mitigation Zone and 

Requirements—200 yd around the 

intended impact location. 

(A) Prior to the start of the activity 

(e.g., when maneuvering on station), the 

Navy shall observe for floating 

vegetation and marine mammals; if 

resource is observed, the Navy shall not 

commence firing. 

(B) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease firing. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence firing 

until one of the recommencement 

conditions has been met: The animal is 

observed exiting the mitigation zone; 

the animal is thought to have exited the 

mitigation zone based on a 

determination of its course, speed, and 

movement relative to the intended 

impact location; the mitigation zone has 

been clear from any additional sightings 

for 10 min for aircraft-based firing or 30 

min for vessel-based firing; or for 

activities using a mobile target, the 

intended impact location has transited a 

distance equal to double that of the 

mitigation zone size beyond the location 

of the last sighting. 

(19) Non-Explosive Missiles and 

Rockets. Aircraft-deployed nonexplosive missiles and rockets. 

Mitigation applies to activities using a 

surface target. 

(i) Number of Lookouts and 

Observation Platform—One Lookout 

positioned in an aircraft. 

(ii) Mitigation Zone and 

Requirements—900 yd around the 

intended impact location. 

(A) Prior to the start of the activity 

(e.g., during a fly-over of the mitigation 

zone), the Navy shall observe for 

floating vegetation and marine 

mammals; if resource is observed, the 

Navy shall not commence firing. 

(B) During the activity, the Navy shall 

observe for marine mammals; if resource 

is observed, the Navy shall cease firing. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence firing 

until one of the recommencement 

conditions has been met: The animal is 

observed exiting the mitigation zone; 

the animal is thought to have exited the 

mitigation zone based on a 

determination of its course, speed, and 

movement relative to the intended 

impact location; or the mitigation zone 

has been clear from any additional 

sightings for 10 min when the activity 

involves aircraft that have fuel 

constraints, or 30 min when the activity 

involves aircraft that are not typically 

fuel constrained. 

(20) Non-Explosive Bombs and Mine 

Shapes. Non-explosive bombs and nonexplosive mine shapes during mine 

laying activities. 

(i) Number of Lookouts and 

Observation Platform—One Lookout 

positioned in an aircraft. 

(ii) Mitigation Zone and 

Requirements—1,000 yd around the 

intended target. 

(A) Prior to the start of the activity 

(e.g., when arriving on station), the 

Navy shall observe for floating 

vegetation and marine mammals; if 

resource is observed, the Navy shall not 

commence bomb deployment or mine 

laying. 

(B) During approach of the target or 

intended minefield location, the Navy 

shall observe for marine mammals; if 

resource is observed, the Navy shall 

cease bomb deployment or mine laying. 

(C) To allow an observed marine 

mammal to leave the mitigation zone, 

the Navy shall not recommence bomb 

deployment or mine laying until one of 

the recommencement conditions has 

been met: the animal is observed exiting 

the mitigation zone; the animal is 

thought to have exited the mitigation 

zone based on a determination of its 

course, speed, and movement relative to 

the intended target or minefield 

location; the mitigation zone has been 

clear from any additional sightings for 

10 min; or for activities using mobile 

targets, the intended target has transited 

a distance equal to double that of the 

mitigation zone size beyond the location 

of the last sighting. 

(b) Mitigation Areas. In addition to 

procedural mitigation, the Navy shall 

implement mitigation measures within 

mitigation areas to avoid or reduce 

potential impacts on marine mammals. 

(1) Mitigation Areas Marine Mammals 

in the Hawaii Range Complex for sonar, 

explosives, and strikes. 

(i) Mitigation Area Requirements—(A) 

Hawaii Island Mitigation Area (yearround): 

(1) The Navy shall not exceed 300 

hours of MFAS sensor MF1 (MF1) and 

20 hours of MFAS sensor MF4 (MF4) 

annually. 

(2) Should national security present a 

requirement to conduct more than 300 

hrs of MF1 or 20 hrs of MF4 per year, 

naval units will obtain permission from 

the appropriate designated Command 

authority prior to commencement of the 

activity. The Navy will provide NMFS 

with advance notification and include 

the information (e.g., hours of sonar 

usage) in its annual activity reports. 

(3) The Navy shall not use explosives 

during training or testing activities. 

Explosive restrictions within the Hawaii 

Island Mitigation Area apply only to 

those activities for which the Navy 

seeks MMPA authorization (e.g., 

surface-to-surface or air-to-surface 

missile and gunnery events, BOMBEX, 

and mine neutralization). 

(4) Should national security present a 

requirement for the use of explosives in 

the area, naval units will obtain 

permission from the appropriate 

designated Command authority prior to 

commencement of the activity. The 

Navy will provide NMFS with advance 

notification and include the information 

(e.g., explosives usage) in its annual 

activity reports. 

(B) 4-Islands Region Mitigation Area 

(November 15–April 15): 

(1) The Navy shall not use MFAS 

sensor MF1 during training or testing 

activities from November 15–April 15. 

(2) Should national security present a 

requirement for the use of MF1 in the 

area from November 15–April 15, naval 

units will obtain permission from the 

appropriate designated Command 

authority prior to commencement of the 

activity. The Navy will provide NMFS 

with advance notification and include 

the information (e.g., hours of sonar 

usage) in its annual activity reports. 

(ii) [Reserved] 

(2) Mitigation Areas Marine Mammals 

in the Southern California Portion of the 

Study Area for sonar, explosives, and 

strikes. 

(i) Mitigation Area Requirements—(A) 

San Diego Arc Mitigation Area (June 1– 

October 31): 

(1) The Navy shall not exceed 200 

hours of MFAS sensor MF1 (with the 

exception of active sonar maintenance 

and systems checks) per season 

annually. 

(2) Should national security present a 

requirement to conduct more than 200 

hrs of MF1 (with the exception of active 

sonar maintenance and systems checks) 

per year from June 1–October 31, naval 

units will obtain permission from the 

appropriate designated Command 

authority prior to commencement of the 

activity. The Navy will provide NMFS 

with advance notification and include 

the information (e.g., hours of sonar 

usage) in its annual activity reports. 

(3) The Navy shall not use explosives 

during large-caliber gunnery, torpedo, 

bombing, and missile (including 2.75 


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inch rockets) activities during training 

or testing activities. 

(4) Should national security present a 

requirement to conduct large-caliber 

gunnery, torpedo, bombing, and missile 

(including 2.75 inch rockets) activities 

using explosives, naval units will obtain 

permission from the appropriate 

designated Command authority prior to 

commencement of the activity. The 

Navy will provide NMFS with advance 

notification and include the information 

(e.g., explosives usage) in its annual 

activity reports. 

(B) Santa Barbara Island Mitigation 

Area (year-round): 

(1) The Navy shall not use MFAS 

sensor MF1 and explosives used in 

small-, medium-, and large-caliber 

gunnery; torpedo; bombing; and missile 

(including 2.75 inch rockets) activities 

during unit-level training or MTEs. 

(2) Should national security present a 

requirement for the use of midfrequency active anti-submarine warfare 

sensor MF1 or explosives in small-, 

medium-, and large-caliber gunnery; 

torpedo; bombing; and missile 

(including 2.75 inch rockets) activities 

during unit-level training or major 

training exercises for national security, 

naval units will obtain permission from 

the appropriate designated Command 

authority prior to commencement of the 

activity. The Navy will provide NMFS 

with advance notification and include 

the information in its annual activity 

reports. 

(ii) [Reserved] 

§ 218.75 Requirements for monitoring and 

reporting. 

(a) The Navy must notify NMFS 

immediately (or as soon as operational 

security considerations allow) if the 

specified activity identified in § 218.70 

is thought to have resulted in the 

mortality or injury of any marine 

mammals, or in any take of marine 

mammals not identified in this subpart. 

(b) The Navy must conduct all 

monitoring and required reporting 

under the LOAs, including abiding by 

the HSTT Study Area monitoring 

program. Details on program goals, 

objectives, project selection process, and 

current projects available at www.navy

marinespeciesmonitoring.us. 

(c) Notification of injured, live 

stranded, or dead marine mammals. The 

Navy shall abide by the Notification and 

Reporting Plan, which sets out 

notification, reporting, and other 

requirements when dead, injured, or 

live stranded marine mammals are 

detected. 

(d) Annual HSTT Study Area marine 

species monitoring report. The Navy 

shall submit an annual report of the 

HSTT Study Area monitoring describing 

the implementation and results from the 

previous calendar year. Data collection 

methods shall be standardized across 

range complexes and study areas to 

allow for comparison in different 

geographic locations. The report shall be 

submitted either three months after the 

calendar year, or three months after the 

conclusion of the monitoring year to be 

determined by the Adaptive 

Management process to the Director, 

Office of Protected Resources, NMFS. 

Such a report would describe progress 

of knowledge made with respect to 

intermediate scientific objectives within 

the HSTT Study Area associated with 

the Integrated Comprehensive 

Monitoring Program. Similar study 

questions shall be treated together so 

that progress on each topic shall be 

summarized across all Navy ranges. The 

report need not include analyses and 

content that does not provide direct 

assessment of cumulative progress on 

the monitoring plan study questions. As 

an alternative, the Navy may submit a 

multi-Range Complex annual 

Monitoring Plan report to fulfill this 

requirement. Such a report would 

describe progress of knowledge made 

with respect to monitoring study 

questions across multiple Navy ranges 

associated with the ICMP. Similar study 

questions shall be treated together so 

that progress on each topic shall be 

summarized across multiple Navy 

ranges. The report need not include 

analyses and content that does not 

provide direct assessment of cumulative 

progress on the monitoring study 

question. This will continue to allow 

Navy to provide a cohesive monitoring 

report covering multiple ranges (as per 

ICMP goals), rather than entirely 

separate reports for the HSTT, Gulf of 

Alaska, Mariana Islands, and the 

Northwest Study Areas, etc. 

(e) Annual HSTT Training Exercise 

Report and Testing Activity Report. 

Each year, the Navy shall submit two 

preliminary reports (Quick Look Report) 

detailing the status of authorized sound 

sources within 21 days after the 

anniversary of the date of issuance of 

each LOA to the Director, Office of 

Protected Resources, NMFS. Each year, 

the Navy shall submit detailed reports 

to the Director, Office of Protected 

Resources, NMFS within 3 months after 

the anniversary of the date of issuance 

of the LOA. The HSTT annual Training 

Exercise Report and Testing Activity 

reports can be consolidated with other 

exercise reports from other range 

complexes in the Pacific Ocean for a 

single Pacific Exercise Report, if 

desired. The annual reports shall 

contain information on MTEs, Sinking 

Exercise (SINKEX) events, and a 

summary of all sound sources used, as 

described in paragraph (e)(3) of this 

section. The analysis in the detailed 

reports shall be based on the 

accumulation of data from the current 

year’s report and data collected from 

previous reports. The detailed reports 

shall contain information identified in 

paragraphs (e)(1) through (5) of this 

section. 

(1) MTEs—This section shall contain 

the following information for MTEs 

conducted in the HSTT Study Area. 

(i) Exercise Information (for each 

MTE): 

(A) Exercise designator; 

(B) Date that exercise began and 

ended; 

(C) Location; 

(D) Number and types of active sonar 

sources used in the exercise; 

(E) Number and types of passive 

acoustic sources used in exercise; 

(F) Number and types of vessels, 

aircraft, etc., participating in exercise; 

(G) Total hours of observation by 

lookouts; 

(H) Total hours of all active sonar 

source operation; 

(I) Total hours of each active sonar 

source bin; and 

(J) Wave height (high, low, and 

average during exercise). 

(ii) Individual marine mammal 

sighting information for each sighting in 

each exercise when mitigation occurred: 

(A) Date/Time/Location of sighting; 

(B) Species (if not possible, indication 

of whale/dolphin/pinniped); 

(C) Number of individuals; 

(D) Initial Detection Sensor; 

(E) Indication of specific type of 

platform observation made from 

(including, for example, what type of 

surface vessel or testing platform); 

(F) Length of time observers 

maintained visual contact with marine 

mammal; 

(G) Sea state; 

(H) Visibility; 

(I) Sound source in use at the time of 

sighting; 

(J) Indication of whether animal is 

<200 yd, 200 to 500 yd, 500 to 1,000 yd, 

1,000 to 2,000 yd, or >2,000 yd from 

sonar source; 

(K) Mitigation implementation. 

Whether operation of sonar sensor was 

delayed, or sonar was powered or shut 

down, and how long the delay was; 

(L) If source in use is hull-mounted, 

true bearing of animal from ship, true 

direction of ship’s travel, and estimation 

of animal’s motion relative to ship 

(opening, closing, parallel); and 

(M) Observed behavior. Lookouts 

shall report, in plain language and 


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without trying to categorize in any way, 

the observed behavior of the animals 

(such as animal closing to bow ride, 

paralleling course/speed, floating on 

surface and not swimming, etc.) and if 

any calves present. (iii) An evaluation 

(based on data gathered during all of the 

MTEs) of the effectiveness of mitigation 

measures designed to minimize the 

received level to which marine 

mammals may be exposed. This 

evaluation shall identify the specific 

observations that support any 

conclusions the Navy reaches about the 

effectiveness of the mitigation. 

(2) SINKEXs. This section shall 

include the following information for 

each SINKEX completed that year. 

(i) Exercise information (gathered for 

each SINKEX); 

(A) Location; 

(B) Date and time exercise began and 

ended; 

(C) Total hours of observation by 

lookouts before, during, and after 

exercise; 

(D) Total number and types of 

explosive source bins detonated; 

(E) Number and types of passive 

acoustic sources used in exercise; 

(F) Total hours of passive acoustic 

search time; 

(G) Number and types of vessels, 

aircraft, etc., participating in exercise; 

(H) Wave height in feet (high, low, 

and average during exercise); and 

(J) Narrative description of sensors 

and platforms utilized for marine 

mammal detection and timeline 

illustrating how marine mammal 

detection was conducted. 

(ii) Individual marine mammal 

observation (by Navy lookouts) 

information (gathered for each marine 

mammal sighting) for each sighting 

where mitigation was implemented. 

(A) Date/Time/Location of sighting; 

(B) Species (if not possible, indicate 

whale, dolphin, or pinniped); 

(C) Number of individuals; 

(D) Initial detection sensor; 

(E) Length of time observers 

maintained visual contact with marine 

mammal; 

(F) Sea state; 

(G) Visibility; 

(H) Whether sighting was before, 

during, or after detonations/exercise, 

and how many minutes before or after; 

(I) Distance of marine mammal from 

actual detonations—200 yd, 200 to 500 

yd, 500 to 1,000 yd, 1,000 to 2,000 yd, 

or >2,000 yd (or target spot if not yet 

detonated); 

(J) Observed behavior. Lookouts shall 

report, in plain language and without 

trying to categorize in any way, the 

observed behavior of the animal(s) (such 

as animal closing to bow ride, 

paralleling course/speed, floating on 

surface and not swimming etc.), 

including speed and direction and if 

any calves present; 

(K) Resulting mitigation 

implementation. Indicate whether 

explosive detonations were delayed, 

ceased, modified, or not modified due to 

marine mammal presence and for how 

long; and 

(L) If observation occurs while 

explosives are detonating in the water, 

indicate munition type in use at time of 

marine mammal detection. 

(3) Summary of sources used. This 

section shall include the following 

information summarized from the 

authorized sound sources used in all 

training and testing events: 

(i) Total annual hours or quantity (per 

the LOA) of each bin of sonar or other 

acoustic sources (pile driving and air 

gun activities); 

(ii) Total annual expended/detonated 

rounds (missiles, bombs, sonobuoys, 

etc.) for each explosive bin. 

(4) Humpback Whale Special 

Reporting Area (December 15–April 15). 

The Navy shall report the total hours of 

operation of surface ship hull-mounted 

mid-frequency active sonar used in the 

special reporting area. 

(5) HSTT Mitigation Areas. The Navy 

shall report any use that occurred as 

specifically described in these areas. 

Information included in the classified 

annual reports may be used to inform 

future adaptive management of 

activities within the HSTT Study Area. 

(6) Geographic information 

presentation. The reports shall present 

an annual (and seasonal, where 

practical) depiction of training and 

testing events and bin usage (as well as 

pile driving activities) geographically 

across the HSTT Study Area. 

§ 218.76 Letters of Authorization. 

(a) To incidentally take marine 

mammals pursuant to these regulations 

in this subpart, the Navy must apply for 

and obtain Letters of Authorization 

(LOAs) in accordance with § 216.106 of 

this subpart, conducting the activity 

identified in § 218.70(c). 

(b) LOAs, unless suspended or 

revoked, may be effective for a period of 

time not to exceed the expiration date 

of these regulations in this subpart. 

(c) If an LOA(s) expires prior to the 

expiration date of these regulations in 

this subpart, the Navy may apply for 

and obtain a renewal of the LOA(s). 

(d) In the event of projected changes 

to the activity or to mitigation, 

monitoring, reporting (excluding 

changes made pursuant to the adaptive 

management provision of § 218.77(c)(1)) 

required by an LOA, the Navy must 

apply for and obtain a modification of 

LOAs as described in § 218.77. 

(e) Each LOA shall set forth: 

(1) Permissible methods of incidental 

taking; 

(2) Authorized geographic areas for 

incidental taking; 

(3) Means of effecting the least 

practicable adverse impact (i.e., 

mitigation) on the species of marine 

mammals, their habitat, and the 

availability of the species for 

subsistence uses; and 

(4) Requirements for monitoring and 

reporting. 

(f) Issuance of the LOA(s) shall be 

based on a determination that the level 

of taking shall be consistent with the 

findings made for the total taking 

allowable under these regulations in 

this subpart. 

(g) Notice of issuance or denial of the 

LOA(s) shall be published in the 

Federal Register within 30 days of a 

determination. 

§ 218.77 Renewals and modifications of 

Letters of Authorization. 

(a) An LOA issued under § 216.106 of 

this subchapter and § 218.76 for the 

activity identified in § 218.70(c) shall be 

renewed or modified upon request by 

the applicant, provided that: 

(1) The proposed specified activity 

and mitigation, monitoring, and 

reporting measures, as well as the 

anticipated impacts, are the same as 

those described and analyzed for these 

regulations in this subpart (excluding 

changes made pursuant to the adaptive 

management provision in paragraph 

(c)(1) of this section); and 

(2) NMFS determines that the 

mitigation, monitoring, and reporting 

measures required by the previous 

LOA(s) under these regulations in this 

subpart were implemented. 

(b) For LOA modification or renewal 

requests by the applicant that include 

changes to the activity or the mitigation, 

monitoring, or reporting measures 

(excluding changes made pursuant to 

the adaptive management provision in 

paragraph (c)(1) of this section) that do 

not change the findings made for the 

regulations or result in no more than a 

minor change in the total estimated 

number of takes (or distribution by 

species or years), NMFS may publish a 

notice of proposed LOA in the Federal 

Register, including the associated 

analysis of the change, and solicit 

public comment before issuing the LOA. 

(c) An LOA issued under § 216.106 of 

this subchapter and § 218.76 for the 

activity identified in § 218.70(c) may be 

modified by NMFS under the following 

circumstances: 

(1) Adaptive Management—After 

consulting with the Navy regarding the 


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practicability of the modifications, 

NMFS may modify (including adding or 

removing measures) the existing 

mitigation, monitoring, or reporting 

measures if doing so creates a 

reasonable likelihood of more 

effectively accomplishing the goals of 

the mitigation and monitoring set forth 

in this subpart. 

(i) Possible sources of data that could 

contribute to the decision to modify the 

mitigation, monitoring, or reporting 

measures in an LOA: 

(A) Results from the Navy’s 

monitoring from the previous year(s); 

(B) Results from other marine 

mammal and/or sound research or 

studies; or 

(C) Any information that reveals 

marine mammals may have been taken 

in a manner, extent or number not 

authorized by these regulations in this 

subpart or subsequent LOAs. 

(ii) If, through adaptive management, 

the modifications to the mitigation, 

monitoring, or reporting measures are 

substantial, NMFS shall publish a notice 

of proposed LOA in the Federal 

Register and solicit public comment. 

(2) Emergencies—If NMFS determines 

that an emergency exists that poses a 

significant risk to the well-being of the 

species or stocks of marine mammals 

specified in LOAs issued pursuant to 

§ 216.106 of this chapter and § 217.86, 

an LOA may be modified without prior 

notice or opportunity for public 

comment. Notice would be published in 

the Federal Register within thirty days 

of the action. 

§§ 218.78–218.79 [Reserved] 

[FR Doc. 2018–13115 Filed 6–25–18; 8:45 am] 

BILLING CODE 3510–22–P 


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