[Federal Register Volume 83, Number 123 (Tuesday, June 26, 2018)]
[Proposed Rules]
[Pages 29872-30029]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-13115]



[[Page 29871]]

Vol. 83

Tuesday,

No. 123

June 26, 2018

Part II





Department of Commerce





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National Oceanic and Atmospheric Administration





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50 CFR Part 218





Taking and Importing Marine Mammals; Taking Marine Mammals Incidental 
to the U.S. Navy Training and Testing Activities in the Hawaii-Southern 
California Training and Testing Study Area; Proposed Rule

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

[[Page 29872]]


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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 
Hawaii-Southern 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.

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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 Hawaii-Southern 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:
    <bullet> 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.
    <bullet> 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.
    <bullet> 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-military-readiness-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

[[Page 29873]]

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-military-readiness-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

[[Page 29874]]

terms of the various warfare mission areas in which they would be 
conducted. In terms of Navy's primary warfare areas, this includes:
    <bullet> Amphibious warfare (in-water detonations);
    <bullet> ASW (sonar and other transducers, in-water detonations);
    <bullet> SUW (in-water detonations);
    <bullet> MIW (sonar and other transducers, in-water detonations); 
and
    <bullet> 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-to-shore 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 large-scale 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 high-explosive 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, air-launched 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, anti-ship 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.

[[Page 29876]]

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; anti-terrorism and force protection; mine 
countermeasures; anti[hyphen]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 mid-frequency hull-mounted sonars used to find and track 
enemy submarines; high-frequency 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

[[Page 29877]]

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 hull-mounted) at variable depths 
on moving platforms (ships, helicopters, or unmanned vehicles) to sweep 
a suspected mined area. Most hull-mounted 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:
    <bullet> Frequency of the non-impulsive acoustic source;
    [cir] Low-frequency sources operate below 1 kHz;
    [cir] Mid-frequency sources operate at and above 1 kHz, up to and 
including 10 kHz;
    [cir] High-frequency sources operate above 10 kHz, up to and 
including 100 kHz;
    [cir] Very high-frequency sources operate above 100 kHz but below 
200 kHz;
    <bullet> Sound pressure level of the non-impulsive source;
    [cir] Greater than 160 decibels (dB) re 1 micro Pascal ([mu]Pa), 
but less than 180 dB re 1 [mu]Pa;
    [cir] Equal to 180 dB re 1 [mu]Pa and up to 200 dB re 1 [mu]Pa;
    [cir] Greater than 200 dB re 1 [mu]Pa;
    <bullet> Application in which the source would be used;
    [cir] 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.

[[Page 29878]]



         Table 1--Sonar and Transducers Quantitatively Analyzed
------------------------------------------------------------------------
     Source class category             Bin              Description
------------------------------------------------------------------------
Low-Frequency (LF): Sources      LF3              LF sources greater
 that produce signals less than  LF4               than 200 dB.
 1 kHz.                                           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     MF1              Hull-mounted surface
 and non-tactical sources that   MF1K              ship sonars (e.g., AN/
 produce signals between 1-10                      SQS-53C and AN/SQS-
 kHz.                                              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    HF1              Hull-mounted submarine
 and non-tactical sources that   HF3               sonars (e.g., AN/BQQ-
 produce signals between 10-100                    10).
 kHz.                                             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       VHF1             VHF sources greater
 (VHF): Non-tactical sources                       than 200 dB.
 that produce signals between
 100-200 kHz.
Anti-Submarine Warfare (ASW):    ASW1             MF systems operating
 Tactical sources (e.g., active  ASW2              above 200 dB.
 sonobuoys and acoustic counter- ASW3             MF Multistatic Active
 measures systems) used during                     Coherent sonobuoy
 ASW training and testing                          (e.g., AN/SSQ-125).
 activities.                                      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         TORP1            Lightweight torpedo
 classes associated with the     TORP2             (e.g., MK 46, MK 54,
 active acoustic signals         TORP3             or Anti-Torpedo
 produced by torpedoes.                            Torpedo).
                                                  Heavyweight torpedo
                                                   (e.g., MK 48).
                                                  Heavyweight torpedo
                                                   (e.g., MK 48).
Forward Looking Sonar (FLS):     FLS2             HF sources with short
 Forward or upward looking                         pulse lengths, narrow
 object avoidance sonars used                      beam widths, and
 for ship navigation and safety.                   focused beam
                                                   patterns.
Acoustic Modems (M): Systems     M3               MF acoustic modems
 used to transmit data through                     (greater than 190
 the water.                                        dB).
Swimmer Detection Sonars (SD):   SD1-SD2          HF and VHF sources
 Systems used to detect divers                     with short pulse
 and submerged swimmers.                           lengths, used for the
                                                   detection of swimmers
                                                   and other objects for
                                                   the purpose of port
                                                   security.
Synthetic Aperture Sonars        SAS1             MF SAS systems.
 (SAS): Sonars in which active   SAS2             HF SAS systems.
 acoustic signals are post-      SAS3             VHF SAS systems.
 processed to form high-         SAS4             MF to HF broadband
 resolution images of the                          mine countermeasure
 seafloor.                                         sonar.
Broadband Sound Sources (BB):    BB1              MF to HF mine
 Sonar systems with large        BB2               countermeasure sonar.
 frequency spectra, used for     BB4              HF to VHF mine
 various purposes.               BB5               countermeasure sonar.
                                 BB6              LF to MF oceanographic
                                 BB7               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 (in\3\) would be 
used during testing activities in various offshore areas of the 
Southern California Range Complex and in the Hawaii Range Complex.

[[Page 29879]]

    Generated impulses would have short durations, typically a few 
hundred milliseconds, with dominant frequencies below 1 kHz. The root-
mean-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 
[mu]Pa and 227 dB re 1 [mu]Pa, respectively, if operated at the full 
capacity of 60 in\3\. 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 non-impulsive 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 [mu]Pa SPL rms.
                                                 182 dB re 1 [mu]Pa\2\s SEL (single strike).
24-in. Steel Pipe Pile.......  Vibratory 2.....  146 dB re 1 [mu]Pa SPL rms.
                                                 145 dB re 1 [mu]Pa\2\s 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
  [mu]Pa = 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 [mu]Pa 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 [mu]Pa (94 dB re 20 [mu]Pa) 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.

[[Page 29880]]

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
------------------------------------------------------------------------
                              Net explosive weight    Example explosive
             Bin                     1  (lb)               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.
2 E13 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 in-air 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; Berman-Kowalewski 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;

[[Page 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 mid-frequency active sonar estimated to be 
necessary to meet training requirements. It also means that the Navy is 
requesting fewer hours of hull-mounted mid-frequency 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.
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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 6 summarizes the proposed testing activities for the Naval 
Sea Systems Command analyzed within the HSTT Study Area.
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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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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.
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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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    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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Training                           Testing
         Source class category                   Bin                  Unit \1\       -------------------------------------------------------------------
                                                                                           Annual        5-year total        Annual        5-year total
--------------------------------------------------------------------------------------------------------------------------------------------------------
Air Guns (AG): Small underwater air     AG                     C                                   0                0              844            4,220
 guns.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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
----------------------------------------------------------------------------------------------------------------
                                                                                                       Total
                                                                                                  estimated time
                             Method                                Piles per 24-   Time per pile   of noise per
                                                                    hour period      (minutes)    24-hour period
                                                                                                     (minutes)
----------------------------------------------------------------------------------------------------------------
Pile Driving (Impact)...........................................               6              15              90
Pile Removal (Vibratory)........................................              12               6              72
----------------------------------------------------------------------------------------------------------------

    Table 12 shows the number of in-water 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.

[[Page 29905]]



                 Table 12--Explosive Source Bins Analyzed and Numbers Used During Training and Testing Activities in the HSTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             Training                   Testing
                           Net explosive                                    Modeled underwater     -----------------------------------------------------
           Bin              weight (lb)     Example explosive source    detonation depths (ft) \1\                    5-year                     5-year
                                                                                                        Annual        total        Annual        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.  NA \2\.....................               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:
    <bullet> Ship, submarine, and aircraft safety manuals;
    <bullet> Ship, submarine, and aircraft standard operating manuals;
    <bullet> Fleet Area Control and Surveillance Facility range 
operating instructions;
    <bullet> Fleet exercise publications and instructions;
    <bullet> Naval Sea Systems Command test range safety and standard 
operating instructions;
    <bullet> Navy instrumented range operating procedures;
    <bullet> Naval shipyard sea trial agendas;
    <bullet> Research, development, test, and evaluation plans;
    <bullet> Naval gunfire safety instructions;
    <bullet> Navy planned maintenance system instructions and 
requirements;
    <bullet> Federal Aviation Administration regulations; and
    <bullet> 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.

    <bullet> Vessel Safety
    <bullet> Weapons Firing Safety
    <bullet> Target Deployment Safety
    <bullet> Towed In-Water Device Safety
    <bullet> 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

[[Page 29906]]

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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

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 
(nmi\2\) 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 nmi\2\ of special use airspace and ocean areas. The HRC 
includes over 115,000 nmi\2\ 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 nmi\2\ 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 
(mi\2\) to 582,578 mi\2\. 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 nmi\2\ of sea space and 113,000 nmi\2\ 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 
nmi\2\ of airspace. The SOCAL Range Complex includes approximately 
120,000 nmi\2\ 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 nmi\2\) 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 anti-submarine 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

[[Page 29907]]

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-mammal-stock-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
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                   Status
            Common name                Scientific name             Stock        --------------------------------------------      Occurrence         Seasonal absence     Stock abundance (CV)/
                                                                                         MMPA                   ESA                                                         minimum population
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale........................  Balaenoptera musculus  Eastern North         Depleted............  Endangered..........  Southern California.  ....................       1,647 (0.07)/1,551
                                                            Pacific.
                                                           Central North         Depleted............  Endangered..........  Hawaii..............  Summer..............             81 (1.14)/38
                                                            Pacific.
Bryde's whale.....................  Balaenoptera brydei/   Eastern Tropical      ....................  ....................  Southern California.  ....................                  unknown
                                     edeni.                 Pacific.
                                                           Hawaiian............  Depleted............  ....................  Hawaii..............  ....................           798 (0.28)/633
Fin whale.........................  Balaenoptera physalus  California, Oregon,   Depleted............  Endangered..........  Southern California.  ....................       9,029 (0.12)/8,127
                                                            and Washington.
                                                           Hawaiian............  Depleted............  Endangered..........  Hawaii..............  Summer..............             58 (1.12)/27
Gray whale........................  Eschrichtius robustus  Eastern North         ....................  ....................  Southern California.  ....................     20,990 (0.05)/20,125
                                                            Pacific.
                                                           Western North         Depleted............  Endangered..........  Southern California.  ....................           140 (0.04)/135
                                                            Pacific.
Humpback whale....................  Megaptera              California, Oregon,   Depleted............  Threatened/           Southern California.  ....................       1,918 (0.03)/1,876
                                     novaeangliae.          and Washington.                             Endangered \1\.
                                                           Central North         ....................  ....................  Hawaii..............  Summer..............      10,103 (0.30)/7,890
                                                            Pacific.
Minke whale.......................  Balaenoptera           California, Oregon,   ....................  ....................  Southern California.  ....................           636 (0.72)/369
                                     acutorostrata.         and Washington.
                                                           Hawaiian............  ....................  ....................  Hawaii..............  Summer..............                  unknown

[[Page 29908]]

 
Sei whale.........................  Balaenoptera borealis  Eastern North         Depleted............  Endangered..........  Southern California.  ....................            519 (0.4)/374
                                                            Pacific.
                                                           Hawaii..............  Depleted............  Endangered..........  Hawaii..............  Summer..............            178 (0.90)/93
Sperm whale.......................  Physeter               California, Oregon,   Depleted............  Endangered..........  Southern California.  ....................       2,106 (0.58)/1,332
                                     macrocephalus.         and Washington.
                                                           Hawaiian............  Depleted............  Endangered..........  Hawaii..............  ....................       3,354 (0.34)/2,539
Pygmy sperm whale.................  Kogia breviceps......  California, Oregon,   ....................  ....................  Southern California.  Winter and Fall.....       4,111 (1.12)/1,924
                                                            and Washington.
                                                           Hawaiian............  ....................  ....................  Hawaii..............  ....................                  unknown
Dwarf sperm whale.................  Kogia sima...........  California, Oregon,   ....................  ....................  Southern California.  ....................                  unknown
                                                            and Washington.
                                                           Hawaiian............  ....................  ....................  Hawaii..............  ....................                  unknown
Baird's beaked whale..............  Berardius bairdii....  California, Oregon,   ....................  ....................  Southern California.  ....................           847 (0.81)/466
                                                            and Washington.
Blainville's beaked whale.........  Mesoplodon             Hawaiian............  ....................  ....................  Hawaii..............  ....................       2,338 (1.13)/1,088
                                     densirostris.
Cuvier's beaked whale.............  Ziphius cavirostris..  California, Oregon,   ....................  ....................  Southern California.  ....................       6,590 (0.55)/4,481
                                                            and Washington.
                                                           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,   ....................  ....................  Southern California.  ....................           694 (0.65)/389
                                                            and Washington.
Common Bottlenose dolphin.........  Tursiops truncatus...  California Coastal..  ....................  ....................  Southern California.  ....................           453 (0.06)/346
                                                           California, Oregon,                                                                                                1,924 (0.54)/1,255
                                                            and Washington
                                                            Offshore.
                                                           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         Depleted............  Endangered..........  Hawaii..............  ....................            151 (0.20)/92
                                                            Islands Insular.
                                                           Hawaii Pelagic......  ....................  ....................  Hawaii..............  ....................         1,540 (0.66)/928
                                                           Northwestern          ....................  ....................  Hawaii..............  ....................           617 (1.11)/290
                                                            Hawaiian Islands.
Fraser's dolphin..................  Lagenodelphis hosei..  Hawaiian............  ....................  ....................  Hawaii..............  ....................     16,992 (0.66)/10,241
Killer whale......................  Orcinus orca.........  Eastern North         ....................  ....................  Southern California.  ....................           240 (0.49)/162
                                                            Pacific Offshore.
                                                           Eastern North         ....................  ....................  Southern California.  ....................          243 unknown/243
                                                            Pacific Transient/
                                                            West Coast
                                                            Transient \2\.
                                                           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....  ....................  ....................  Hawaii..............  ....................       5,794 (0.20)/4,904
                                                           Kohala Resident.....                                                                                                   447 (0.12)/404
Northern right whale dolphin......  Lissodelphis borealis  California, Oregon,   ....................  ....................  Southern California.  ....................     26,556 (0.44)/18,608
                                                            and Washington.
Pacific white-sided dolphin.......  Lagenorhynchus         California, Oregon,   ....................  ....................  Southern California.  ....................     26,814 (0.28)/21,195
                                     obliquidens.           and Washington.
Pantropical spotted dolphin.......  Stenella attenuata...  Oahu................  ....................  ....................  Hawaii..............  ....................                  unknown
                                                           4-Islands...........                                                                                                          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,   ....................  ....................  Southern California.  ....................       6,336 (0.32)/4,817
                                                            and Washington.
                                                           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

[[Page 29909]]

 
Short-beaked common dolphin.......  Delphinus delphis....  California, Oregon,   ....................  ....................  Southern California.  ....................   969,861 (0.17)/839,325
                                                            and Washington.
Short-finned pilot whale..........  Globicephala           California, Oregon,   ....................  ....................  Southern California.  ....................           836 (0.79)/466
                                     macrorhynchus.         and Washington.
                                                           Hawaiian............  ....................  ....................  Hawaii..............  ....................      12,422 (0.43)/8,782
Spinner dolphin...................  Stenella longirostris  Hawaii Pelagic......  ....................  ....................  Hawaii..............  ....................                  unknown
                                                           Hawaii Island.......                                                                                                   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,   ....................  ....................  Southern California.  ....................     29,211 (0.20)/24,782
                                                            and Washington.
                                                           Hawaiian............  ....................  ....................  Hawaii..............  ....................     20,650 (0.36)/15,391
Dall's porpoise...................  Phocoenoides dalli...  California, Oregon,   ....................  ....................  Southern California.  ....................     25,750 (0.45)/17,954
                                                            and Washington.
Harbor seal.......................  Phoca vitulina.......  California..........  ....................  ....................  Southern California.  ....................         30,968 na/27,348
Hawaiian monk seal................  Neomonachus            Hawaiian............  Depleted............  Endangered..........  Hawaii..............  ....................           1,272 na/1,205
                                     schauinslandi.
Northern elephant seal............  Mirounga               California..........  ....................  ....................  Southern California.  ....................        179,000 na/81,368
                                     angustirostris.
California sea lion...............  Zalophus               U.S. Stock..........  ....................  ....................  Southern California.  ....................       296,750 na/153,337
                                     californianus.
Guadalupe fur seal................  Arctocephalus          Mexico to California  Depleted............  Threatened..........  Southern California.  ....................         20,000 na/15,830
                                     townsendi.
Northern fur seal.................  Callorhinus ursinus..  California..........  ....................  ....................  Southern California.  ....................          14,050 na/7,524
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
\1\ The 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.
\2\ This 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,

[[Page 29910]]

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/biologically-important-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,

[[Page 29911]]

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 site-specific 
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 nmi\2\ 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 ecosystem-based 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

[[Page 29912]]

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 Ni[ntilde]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-mortality-event-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-mortality-event-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 low-frequency 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):
    <bullet> Low-frequency cetaceans (mysticetes): Generalized hearing 
is estimated to occur between approximately 7 Hz and 35 kHz;
    <bullet> Mid-frequency cetaceans (larger toothed whales, beaked 
whales, and most delphinids): Generalized hearing is estimated to occur 
between approximately 150 Hz and 160 kHz;
    <bullet> 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;
    <bullet> Pinnipeds in water; Phocidae (true seals): Generalized 
hearing is estimated to occur between approximately 50 Hz to 86 kHz; 
and
    <bullet> 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 
(Hemil[auml] 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

[[Page 29913]]

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 non-impulsive (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 noise-induced 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; G[ouml]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 noise-
induced 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

[[Page 29914]]

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 non-impulsive 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 high-
frequency 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

[[Page 29915]]

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 
gas-supersaturated 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 [mu]Pa 
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 [mu]Pa 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; 
Fern[aacute]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 bubble-induced 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 (P<INF>N2</INF>) 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 P<INF>N2</INF> 
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 P<INF>N2</INF>. Also, 
results showed that dive profiles had a larger influence on end-dive 
P<INF>N2</INF> than body mass differences between species. Despite diel 
changes (i.e., variation that occurs regularly every day or most days) 
in dive behavior, P<INF>N2</INF> levels showed no consistent trend. 
Model output suggested that all three species live with tissue 
P<INF>N2</INF> 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,

[[Page 29916]]

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 P<INF>N2</INF> 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 N<INF>2</INF> 
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, long-finned 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 CO<INF>2</INF> may 
initiate bubble formation and growth, while elevated levels of 
N<INF>2</INF> may be important for continued bubble growth. The authors 
also suggest that if CO<INF>2</INF> plays an important role in bubble 
formation, a cetacean escaping a sound source may experience increased 
metabolic rate, CO<INF>2</INF> 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 N<INF>2.</INF> Therefore, further information is 
needed to understand the relationship between exposure to stimuli, 
behavioral response (discussed in more detail below), elevated 
N<INF>2</INF> 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 non-auditory 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 high-frequency 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

[[Page 29917]]

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 
high-frequency sound. Human data indicate low-frequency sound can mask 
high-frequency 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 high-
frequencies these cetaceans use to echolocate, but not at the low-to-
moderate 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 [mu]Pa (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)/mid-frequency 
active sonar (MFAS)/high-frequency 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

[[Page 29918]]

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 hypothalamus-
pituitary-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 pre-pathological 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

[[Page 29919]]

``distress'' upon exposure to high frequency, mid-frequency, and low-
frequency 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 1[micro]Pa) 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 1[micro]Pa) 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 1[micro]Pa) 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.

[[Page 29920]]

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 
phase-in 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

[[Page 29921]]

less likely to produce low frequency calls usually associated with 
feeding behavior (Melc[oacute]n et al., 2012). However, Melc[oacute]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 (Melc[oacute]n et al., 2012). 
Additionally, the likelihood of an animal calling decreased with the 
increased received level of mid-frequency sonar, beginning at a SPL of 
approximately 110-120 dB re 1 [micro]Pa (Melc[oacute]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 mid-
frequency 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 
long-term 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 low-frequency 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

[[Page 29922]]

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 ([micro]Pa2-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 [micro]Pa 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 1[micro]Pa. 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 
mid-frequency submarine sonar pulses, in the range of 1000 Hz to 10,000 
Hz (IWC, 2005).

[[Page 29923]]

    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 non-pulse 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, low-frequency 
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 [micro]Pa range and an 
increasing likelihood of avoidance and other behavioral effects in the 
120 to 160 dB re: 1 [micro]Pa 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 [micro]Pa, while in other cases these 
responses were not seen in the 120 to 150 dB re: 1 [micro]Pa 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 [micro]Pa), at least for initial exposures. All recorded exposures 
above 140 dB re: 1 [micro]Pa 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 non-pulse 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 [micro]Pa 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 re1[micro]Pa). 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

[[Page 29924]]

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 1[mu]Pa, 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 
[micro]Pa 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: 
1[mu]Pa 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

[[Page 29925]]

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 [micro]Pa 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 [micro]Pa.
    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 
[micro]Pa, and by 90 percent of animals at 190 dB re 1 [micro]Pa, 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 
pre-disturbance 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 
low-frequency 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.

[[Page 29926]]

    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 (Miksis-Olds, 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.,

[[Page 29927]]

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 low-elevation 
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 five-day 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 x 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 short-term 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

[[Page 29928]]

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 project-specific 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-mammal-stranding-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 intensively-
studied 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 long-beaked 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 long-beaked 
common dolphins near the

[[Page 29929]]

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 in\3\ (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 mid-
frequency active sonar activity. In these circumstances, exposure to 
non-impulsive 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: 1[mu]Pa, 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

[[Page 29930]]

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 cause-and-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

[[Page 29931]]

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; Fern[aacute]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

[[Page 29932]]

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 melon-headed 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 anti-submarine 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;

[[Page 29933]]

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 high-
intensity sonar could indirectly result in physical harm to the beaked 
whales, through the mechanisms described above (gas bubble formation or 
non-elimination 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; 
Fern[aacute]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

[[Page 29934]]

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 human-related 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 
live-stranded 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

[[Page 29935]]

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, low-
frequency 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

[[Page 29936]]

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[oslash]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 mid-frequency 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 life-history 
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 bottom-placed 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

[[Page 29937]]

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 in-water 
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 short-term 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 [mu]Pa\2\ and 400 Hz, 139 to 141 dB 
re 1 [mu]Pa\2\). 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 
[mu]Pa\2\[middot]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 low-frequency 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 high-frequency 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

[[Page 29938]]

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 macro-invertebrates. 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 habitat-mediated 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 population-level 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

[[Page 29939]]

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 short-beaked 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

[[Page 29940]]

marine mammal groups (based on hearing sensitivity) as a result of 
exposure to noise from two different types of sources (impulsive or 
non-impulsive). 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
------------------------------------------------------------------------
                                                   Non-impulsive
                                         -------------------------------
        Functional hearing group           TTS threshold   PTS threshold
                                          SEL (weighted)  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 [mu]Pa\2\s.

    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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                         Mean onset
    Functional hearing group           Species       Weighted onset TTS  Weighted onset PTS   Mean onset slight  GI      slight lung       Mean onset
                                                                                                   tract injury            injury           mortality
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low-frequency cetaceans........  All mysticetes....  168 dB SEL or 213   183 dB SEL or 219   237 dB Peak SPL........  Equation 1......  Equation 2.
                                                      dB Peak SPL.        dB Peak SPL.
Mid-frequency cetaceans........  Most delphinids,    170 dB SEL or 224   185 dB SEL or 230   237 dB Peak SPL........
                                  medium and large    dB Peak SPL.        dB Peak SPL.
                                  toothed whales.
High-frequency cetaceans.......  Porpoises and       140 dB SEL or 196   155 dB SEL or 202   237 dB Peak SPL........
                                  Kogia spp.          dB Peak SPL.        dB Peak SPL.
Phocidae.......................  Harbor seal,        170 dB SEL or 212   185 dB SEL or 218   237 dB Peak SPL........
                                  Hawaiian monk       dB Peak SPL.        dB Peak SPL.
                                  seal, Northern
                                  elephant seal.
Otariidae......................  California sea      188 dB SEL or 226   203 dB SEL or 232   237 dB Peak SPL........
                                  lion, Guadalupe     dB Peak SPL.        dB Peak SPL.
                                  fur seal,
                                  Northern fur seal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
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

[[Page 29941]]

section under ``Acoustically Mediated Bubble Growth and other Pressure-
related 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 [mu]Pa (rms) 
for continuous (e.g., vibratory pile-driving, drilling) and above 160 
dB re 1 [mu]Pa (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 [micro]Pa (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 [mu]Pa) 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 [micro]Pa: 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 peer-reviewed 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 [mu]Pa and 140 dB re 1 [mu]Pa 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

[[Page 29942]]

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 
[mu]Pa @ 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
                             [micro]Pa @1 m
------------------------------------------------------------------------
                                           Moderate SL/
                                              single      High SL/ multi-
             Criteria group                  platform        platform
                                              cutoff          cutoff
                                           distance (km)   distance (km)
------------------------------------------------------------------------
Odontocetes.............................              10              20
Pinnipeds...............................               5              10
Mysticetes..............................              10              20
Beaked Whales...........................              25              50
Harbor Porpoise.........................              20              40
------------------------------------------------------------------------
Notes: dB re 1 [micro]Pa @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.
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[[Page 29943]]

[GRAPHIC] [TIFF OMITTED] TP26JN18.094


[[Page 29944]]


    Tables 19 through Table 21 illustrates the potentially significant 
behavioral response for MFAS.
[GRAPHIC] [TIFF OMITTED] TP26JN18.095


[[Page 29945]]


[GRAPHIC] [TIFF OMITTED] TP26JN18.096


[[Page 29946]]


[GRAPHIC] [TIFF OMITTED] TP26JN18.097


[[Page 29947]]


    Table 22 illustrates the potentially significant behavioral 
response for HFAS.
[GRAPHIC] [TIFF OMITTED] TP26JN18.098

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[[Page 29948]]

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
------------------------------------------------------------------------
                                        Functional hearing       SEL
               Medium                         group           (weighted)
------------------------------------------------------------------------
Underwater..........................  LF                             163
Underwater..........................  MF                             165
Underwater..........................  HF                             135
Underwater..........................  PW                             165
Underwater..........................  OW                             183
------------------------------------------------------------------------
Note: Weighted SEL thresholds in dB re 1 [mu]Pa\2\s 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 SPL<INF>rms</INF> 
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

[[Page 29949]]

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
----------------------------------------------------------------------------------------------------------------
                                           Approximate range in meters for PTS from 30 seconds exposure
    Functional hearing group     -------------------------------------------------------------------------------
                                   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)
----------------------------------------------------------------------------------------------------------------
\1\ PTS 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
----------------------------------------------------------------------------------------------------------------
                                                                Approximate TTS ranges (meters) \1\
                                                 ---------------------------------------------------------------
                  Hearing group                     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
----------------------------------------------------------------------------------------------------------------
                                                      Approximate TTS ranges (meters) \1\
                             -----------------------------------------------------------------------------------
        Hearing group                         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.


[[Page 29950]]


     Table 27--Ranges to Temporary Threshold Shift (meters) for Sonar Bin MF4 Over a Representative Range of
                                     Environments Within the HSTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                      Approximate TTS ranges (meters) \1\
                             -----------------------------------------------------------------------------------
        Hearing group                           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
----------------------------------------------------------------------------------------------------------------
                                                      Approximate TTS ranges (meters) \1\
                             -----------------------------------------------------------------------------------
        Hearing group                              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
----------------------------------------------------------------------------------------------------------------
                                                      Approximate TTS ranges (meters) \1\
                             -----------------------------------------------------------------------------------
        Hearing group                           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

[[Page 29951]]

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 High-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Range to effects for explosives: high frequency cetacean \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                             Source depth
                    Bin                           (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)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average 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 Mid-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Range to effects for explosives: mid-frequency cetacean 1
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Source depth
                        Bin                                (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)

[[Page 29952]]

 
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)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 Average 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 Low-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Range to effects for explosives: low frequency cetacean 1
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Source depth
                        Bin                                (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)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 Average 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.

[[Page 29953]]



                            Table 33--SEL-Based Ranges (meters) to Onset PTS, Onset TTS, and Behavioral Reaction for Phocids
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Range to effects for explosives: phocids 1
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Source depth
                        Bin                                (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)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average 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 1 range to effects for explosives: mid-frequency cetacean
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Source depth
                        Bin                                (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)

[[Page 29954]]

 
                                                                0.1               3          172 (170-180)        694 (480-1,025)        924 (575-1,275)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 Average 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 non-auditory 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]
------------------------------------------------------------------------
                                                         Range (m) (min-
                          Bin                                 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)
E12...................................................     232 (110-775)
------------------------------------------------------------------------
Note:
\1\ Average 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.

    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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           Animal mass intervals (kg) 1
                           Bin                           -----------------------------------------------------------------------------------------------
                                                                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:
\1\ Average 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 in\3\) 
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 [micro]Pa and 227 dB re 1 [micro]Pa, respectively, if operated at 
the full capacity of 60 in\3\. 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

[[Page 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)
----------------------------------------------------------------------------------------------------------------
\1\ Average 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.
\2\ Behavioral 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)
----------------------------------------------------------------------------------------------------------------
\1\ Average 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.
\2\ Behavioral 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

[[Page 29956]]

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.

[[Page 29957]]

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.
    <bullet> Acoustics (sonar and other transducers; air guns; pile 
driving/extraction).
    <bullet> Explosives (explosive shock wave and sound (assumed to 
encompass the risk due to fragmentation).
    <bullet> 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 model-
estimated 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 x Visibility x 
Observation Area x 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 x 
Model-Estimated 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

[[Page 29958]]

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 model-predicted 
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
----------------------------------------------------------------------------------------------------------------
                                                              Annual                      5-Year total **
            Species                   Stock      ---------------------------------------------------------------
                                                      Level B         Level A         Level B         Level A
----------------------------------------------------------------------------------------------------------------
                                       Suborder Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
                                        Family Balaenopteridae (rorquals)
----------------------------------------------------------------------------------------------------------------
Blue whale *..................  Central North                 34               0             139               0
                                 Pacific.
                                Eastern North              1,155               1           5,036               3
                                 Pacific.
Bryde's whale [dagger]........  Eastern Tropical              27               0             118               0
                                 Pacific.
                                Hawaiian                     105               0             429               0
                                 [dagger].
Fin whale *...................  California,                1,245               0           5,482               0
                                 Oregon, and
                                 Washington.
                                Hawaiian........              33               0             133               0
Humpback whale [dagger].......  California,                1,254               1           5,645               3
                                 Oregon, and
                                 Washington
                                 [dagger].
                                Central North              5,604               1          23,654               5
                                 Pacific.
Minke whale...................  California,                  649               1           2,920               4
                                 Oregon, and
                                 Washington.
                                Hawaiian........           3,463               1          13,664               2
Sei whale *...................  Eastern North                 53               0             236               0
                                 Pacific.
                                Hawaiian........             118               0             453               0
----------------------------------------------------------------------------------------------------------------
                                              Family Eschrichtiidae
----------------------------------------------------------------------------------------------------------------
Gray whale [dagger]...........  Eastern North              2,751               5          11,860              19
                                 Pacific.
                                Western North                  4               0              14               0
                                 Pacific
                                 [dagger].
----------------------------------------------------------------------------------------------------------------
                                      Suborder Odontoceti (toothed whales)
----------------------------------------------------------------------------------------------------------------
                                        Family Physeteridae (sperm whale)
----------------------------------------------------------------------------------------------------------------
Sperm whale *.................  California,                1,397               0           6,257               0
                                 Oregon, and
                                 Washington.
                                Hawaiian........           1,714               0           7,078               0
----------------------------------------------------------------------------------------------------------------
                                         Family Kogiidae (sperm whales)
----------------------------------------------------------------------------------------------------------------
Dwarf sperm whale.............  Hawaiian........          13,961              35          57,571             148

[[Page 29959]]

 
Pygmy sperm whale.............  Hawaiian........           5,556              16          22,833              64
Kogia whales..................  California,                6,012              23          27,366             105
                                 Oregon, and
                                 Washington.
----------------------------------------------------------------------------------------------------------------
                                        Family Ziphiidae (beaked whales)
----------------------------------------------------------------------------------------------------------------
Baird's beaked whale..........  California,                1,317               0           6,044               0
                                 Oregon, and
                                 Washington.
Blainville's beaked whale.....  Hawaiian........           3,687               0          16,364               0
Cuvier's beaked whale.........  California,                6,965               0          32,185               0
                                 Oregon, and
                                 Washington.
                                Hawaiian........           1,235               0           5,497               0
Longman's beaked whale........  Hawaiian........          13,010               0          57,172               0
Mesoplodon spp................  California,                3,750               0          17,329               0
                                 Oregon, and
                                 Washington.
----------------------------------------------------------------------------------------------------------------
                                          Family Delphinidae (dolphins)
----------------------------------------------------------------------------------------------------------------
Bottlenose dolphin............  California                   214               0             876               0
                                 Coastal.
                                California,               31,986               2         142,966               9
                                 Oregon, and
                                 Washington
                                 Offshore.
                                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 [dagger]...  Hawaii Pelagic..             701               0           3,005               0
                                Main Hawaiian                405               0           1,915               0
                                 Islands
                                 Insular[dagger].
                                Northwestern                 256               0           1,094               0
                                 Hawaiian
                                 Islands.
Fraser's dolphin..............  Hawaiian........          28,409               1         122,784               3
Killer whale..................  Eastern North                 73               0             326               0
                                 Pacific
                                 Offshore.
                                Eastern North                135               0             606               0
                                 Pacific
                                 Transient/West
                                 Coast Transient.
                                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,               56,820               8         253,068              40
                                 Oregon, and
                                 Washington.
Pacific white-sided dolphin...  California,               43,914               3         194,882              12
                                 Oregon, and
                                 Washington.
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,               76,276               6         338,560              30
                                 Oregon, and
                                 Washington.
                                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,              932,453              46       4,161,283             222
                                 Oregon, and
                                 Washington.
Short-finned pilot whale......  California,                  990               1           4,492               5
                                 Oregon, and
                                 Washington.
                                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,              119,219               1         550,936               3
                                 Oregon, and
                                 Washington.
                                Hawaiian........           5,388               0          22,526               0
----------------------------------------------------------------------------------------------------------------
                                         Family Phocoenidae (porpoises)
----------------------------------------------------------------------------------------------------------------
Dall's porpoise...............  California,               27,282             137         121,236             634
                                 Oregon, and
                                 Washington.
----------------------------------------------------------------------------------------------------------------
                                               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

[[Page 29960]]

 
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.
[dagger] 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
----------------------------------------------------------------------------------------------------------------
                                                              Annual                      5-Year total **
            Species                   Stock      ---------------------------------------------------------------
                                                      Level B         Level A         Level B         Level A
----------------------------------------------------------------------------------------------------------------
                                       Suborder Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
                                        Family Balaenopteridae (rorquals)
----------------------------------------------------------------------------------------------------------------
Blue whale *..................  Central North                 14               0              65               0
                                 Pacific.
                                Eastern North                833               0           4,005               0
                                 Pacific.
Bryde's whale [dagger]........  Eastern Tropical              14               0              69               0
                                 Pacific.
                                Hawaiian                      41               0             194               0
                                 [dagger].
Fin whale *...................  California,                  980               1           4,695               3
                                 Oregon, and
                                 Washington.
                                Hawaiian........              15               0              74               0
Humpback whale [dagger].......  California,                  740               0           3,508               0
                                 Oregon, and
                                 Washington
                                 [dagger].
                                Central North              3,522               2          16,777              10
                                 Pacific.
Minke whale...................  California,                  276               0           1,309               0
                                 Oregon, and
                                 Washington.
                                Hawaiian........           1,467               1           6,918               4
Sei whale *...................  Eastern North                 26               0             124               0
                                 Pacific.
                                Hawaiian........              49               0             229               0
----------------------------------------------------------------------------------------------------------------
                                              Family Eschrichtiidae
----------------------------------------------------------------------------------------------------------------
Gray whale [dagger]...........  Eastern North              1,920               2           9,277               7
                                 Pacific.
                                Western North                  2               0              11               0
                                 Pacific
                                 [dagger].
----------------------------------------------------------------------------------------------------------------
                                      Suborder Odontoceti (toothed whales)
----------------------------------------------------------------------------------------------------------------
                                        Family Physeteridae (sperm whale)
----------------------------------------------------------------------------------------------------------------
Sperm whale *.................  California,                1,096               0           5,259               0
                                 Oregon, and
                                 Washington.
                                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,                3,120              15          14,643              67
                                 Oregon, and
                                 Washington.
----------------------------------------------------------------------------------------------------------------
                                        Family Ziphiidae (beaked whales)
----------------------------------------------------------------------------------------------------------------
Baird's beaked whale..........  California,                  727               0           3,418               0
                                 Oregon, and
                                 Washington.
Blainville's beaked whale.....  Hawaiian........           1,698               0           8,117               0
Cuvier's beaked whale.........  California,                4,461               0          20,919               0
                                 Oregon, and
                                 Washington.
                                Hawaiian........             561               0           2,675               0
Longman's beaked whale........  Hawaiian........           6,223               0          29,746               0
Mesoplodon spp................  California,                2,402               0          11,262               0
                                 Oregon, and
                                 Washington.
----------------------------------------------------------------------------------------------------------------

[[Page 29961]]

 
                                          Family Delphinidae (dolphins)
----------------------------------------------------------------------------------------------------------------
Bottlenose dolphin............  California                 1,595               0           7,968               0
                                 Coastal.
                                California,               23,436               1         112,410               4
                                 Oregon, and
                                 Washington
                                 Offshore.
                                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 [dagger]...  Hawaii Pelagic..             340               0           1,622               0
                                Main Hawaiian                184               0             892               0
                                 Islands Insular
                                 [dagger].
                                Northwestern                 125               0             594               0
                                 Hawaiian
                                 Islands.
Fraser's dolphin..............  Hawaiian........          12,664               1          60,345               5
Killer whale..................  Eastern North                 34               0             166               0
                                 Pacific
                                 Offshore.
                                Eastern North                 64               0             309               0
                                 Pacific
                                 Transient/West
                                 Coast Transient.
                                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,               41,279               3         198,917              15
                                 Oregon, and
                                 Washington.
Pacific white-sided dolphin...  California,               31,424               2         151,000               8
                                 Oregon, and
                                 Washington.
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,               49,985               3         240,646              15
                                 Oregon, and
                                 Washington.
                                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,              560,120              45       2,673,431             222
                                 Oregon, and
                                 Washington.
Short-finned pilot whale......  California,                  923               0           4,440               0
                                 Oregon, and
                                 Washington.
                                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,               56,035               2         262,973              10
                                 Oregon, and
                                 Washington.
                                Hawaiian........           2,396               0          11,546               0
----------------------------------------------------------------------------------------------------------------
                                         Family Phocoenidae (porpoises)
----------------------------------------------------------------------------------------------------------------
Dall's porpoise...............  California,               17,091              72          81,611             338
                                 Oregon, and
                                 Washington.
----------------------------------------------------------------------------------------------------------------
                                               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.
[dagger] Only designated stocks are ESA-listed.
\1\ NSD: No stock designation.


[[Page 29962]]

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:
    <bullet> Gray whale (Eastern North Pacific stock);
    <bullet> Fin whale (California, Oregon, Washington stock);
    <bullet> Humpback whale (California, Oregon, California stock or 
Mexico DPS);
    <bullet> Humpback whale (Central Pacific stock or Hawaii DPS); and
    <bullet> 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:
    <bullet> Blue whale (Eastern North Pacific stock);
    <bullet> Bryde's whale (Eastern Tropical Pacific stock);
    <bullet> Bryde's whale (Hawaiian stock);
    <bullet> Humpback whale (California, Oregon, California stock or 
Central America DPS);
    <bullet> Minke whale (California, Oregon, Washington stock);
    <bullet> Minke whale (Hawaiian stock);
    <bullet> Sperm whale (California, Oregon, Washington stock);
    <bullet> Sei whale (Hawaiian stock); and
    <bullet> 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:
    <bullet> Blue whale (Central North Pacific stock);
    <bullet> Fin whale (Hawaiian stock); and
    <bullet> 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[hyphen]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

[[Page 29963]]

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.
---------------------------------------------------------------------------

    \2\ A growth rate can be positive, negative, or flat.
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \3\ For 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.
---------------------------------------------------------------------------

    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.merriam-webster.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\
---------------------------------------------------------------------------

    \4\ Outside 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).
---------------------------------------------------------------------------

    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

[[Page 29964]]

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

[[Page 29965]]

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.
---------------------------------------------------------------------------

    \5\ We 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.
---------------------------------------------------------------------------

    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 stock-level 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

[[Page 29966]]

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 in-
depth 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

[[Page 29967]]

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 non-explosive practice munitions, non-explosive missiles 
and rockets, non-explosive bombs and mine shapes).

     Table 43--Procedural Mitigation for Environmental Awareness and
                                Education
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
    <bullet> All training and testing activities, as applicable.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 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:
        <bullet> 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.
        <bullet> Marine Species Awareness Training. All bridge watch
         personnel, Commanding Officers, Executive Officers, maritime
         patrol aircraft aircrews, anti[hyphen]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.
        <bullet> 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.
        <bullet> 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:
            <bullet> 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:
            <bullet> 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.
            <bullet> 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.
            <bullet> 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.

[[Page 29968]]



            Table 44--Procedural Mitigation for Active Sonar
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
    <bullet> Low-frequency active sonar, mid-frequency active sonar,
     high-frequency active sonar.
    <bullet> 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).
    <bullet> 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:
    <bullet> Hull-mounted sources:
        <bullet> Platforms without space or manning restrictions while
         underway: 2 Lookouts at the forward part of the ship.
        <bullet> Platforms with space or manning restrictions while
         underway: 1 Lookout at the forward part of a small boat or ship
        <bullet> Platforms using active sonar while moored or at anchor
         (including pierside): 1 Lookout
    <bullet> Sources that are not hull-mounted:
        <bullet> 1 Lookout on the ship or aircraft conducting the
         activity.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 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.
    <bullet> Low-frequency active sonar at 200 dB or more, and hull-
     mounted mid-frequency active sonar will implement the following
     mitigation zones:
        <bullet> 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.
    <bullet> 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:
        <bullet> During the activity, observe for marine mammals; cease
         active sonar transmission if resource is observed within 200 yd
         of the sonar source.
    <bullet> 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:
    <bullet> Air guns.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned on a ship or pierside.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 150 yd around the air gun:
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease use of air guns.
        <bullet> 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.

[[Page 29969]]



            Table 46--Procedural Mitigation for Pile Driving
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
    <bullet> Pile driving and pile extraction sound during Elevated
     Causeway System Training.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned on the shore, the elevated causeway,
     or a small boat.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 100 yd around the pile driver:
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease impact pile driving or vibratory
         pile extraction.
        <bullet> 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:
    <bullet> Weapons firing noise associated with large-caliber gunnery
     activities.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned on the ship conducting the firing.
    <bullet> Depending on the activity, the Lookout could be the same as
     the one described in Table 50 (Procedural Mitigation for Explosive
     Medium-Caliber 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:
    <bullet> 30 degrees on either side of the firing line out to 70 yd
     from the muzzle of the weapon being fired:
        <bullet> Prior to the start of the activity, observe for
         floating vegetation and marine mammals; if resource is
         observed, do not commence weapons firing.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease weapons firing.
        <bullet> 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:
    <bullet> Explosive sonobuoys.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned in an aircraft or on small boat.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 600 yd around an explosive sonobuoy:
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease sonobuoy or source/receiver pair
         detonations.

[[Page 29970]]

 
        <bullet> 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:
    <bullet> Explosive torpedoes.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned in an aircraft.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 2,100 yd around the intended impact location:
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals and
         jellyfish aggregations; if resource is observed, cease firing.
        <bullet> 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.
        <bullet> 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 medium- and 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:
    <bullet> Gunnery activities using explosive medium-caliber and large-
     caliber projectiles.
    <bullet> Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout on the vessel or aircraft conducting the
     activity.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 200 yd around the intended impact location for air-to-
     surface activities using explosive medium-caliber projectiles, or
    <bullet> 600 yd around the intended impact location for surface-to-
     surface activities using explosive medium-caliber projectiles, or
    <bullet> 1,000 yd around the intended impact location for surface-to-
     surface activities using explosive large-caliber projectiles:
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease firing.
        <bullet> 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.
------------------------------------------------------------------------


[[Page 29971]]

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:
    <bullet> Aircraft-deployed explosive missiles and rockets.
    <bullet> Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned in an aircraft.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 900 yd around the intended impact location during
     activities for missiles or rockets with 0.6-20 lb net explosive
     weight, or
    <bullet> 2,000 yd around the intended impact location for missiles
     with 21-500 lb net explosive weight:
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease firing.
        <bullet> 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:
    <bullet> Explosive bombs.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned in the aircraft conducting the
     activity.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 2,500 yd around the intended target:
        <bullet> 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.
        <bullet> During target approach, observe for marine mammals; if
         resource is observed, cease bomb deployment.
        <bullet> 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:
    <bullet> Sinking exercises.
Number of Lookouts and Observation Platform:
    <bullet> 2 Lookouts (one positioned in an aircraft and one on a
     vessel).
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 2.5 nmi around the target ship hulk:
        <bullet> 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.

[[Page 29972]]

 
        <bullet> During the activity, conduct passive acoustic
         monitoring and visually observe for marine mammals from the
         vessel; if resource is visually observed, cease firing.
        <bullet> 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.
        <bullet> 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.
        <bullet> 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:
    <bullet> Explosive mine countermeasure and neutralization
     activities.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned on a vessel or in an aircraft when
     implementing the smaller mitigation zone.
    <bullet> 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:
    <bullet> 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):
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease detonations.
        <bullet> 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.
        <bullet> 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:
    <bullet> Explosive mine neutralization activities involving Navy
     divers.
Number of Lookouts and Observation Platform:
    <bullet> 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.
    <bullet> 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:
    <bullet> The Navy will not set time-delay firing devices (0.1-29 lb
     net explosive weight) to exceed 10 min.
    <bullet> 500 yd around the detonation site during activities under
     positive control using 0.1-20 lb net explosive weight, or
    <bullet> 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:

[[Page 29973]]

 
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease detonations or fuse initiation.
        <bullet> 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.
        <bullet> 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.
        <bullet> If used, aircraft will travel in a circular pattern
         around the detonation location to the maximum extent
         practicable.
        <bullet> 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.
        <bullet> 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:
    <bullet> Underwater Demolition Multiple Charge--Mat Weave and
     Obstacle Loading exercises.
Number of Lookouts and Observation Platform:
    <bullet> 2 Lookouts (one on a small boat and one on shore from an
     elevated platform).
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 700 yd around the detonation site:
        <bullet> 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.
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease detonations.
        <bullet> 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).
        <bullet> 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:
    <bullet> Maritime Security Operations--Anti-Swimmer Grenades.

[[Page 29974]]

 
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned on the small boat conducting the
     activity.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 200 yd around the intended detonation location:
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease detonations.
        <bullet> 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:
    <bullet> Vessel movement.
    <bullet> 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:
    <bullet> 1 Lookout on the vessel that is underway.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 500 yd around whales:
        <bullet> When underway, observe for marine mammals; if a whale
         is observed, maneuver to maintain distance.
    <bullet> 200 yd around all other marine mammals (except bow-riding
     dolphins and pinnipeds hauled out on man-made navigational
     structures, port structures, and vessels):
        <bullet> 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 In-Water Devices

    Procedural mitigation for towed in-water devices is described in 
Table 59 below.

       Table 59--Procedural Mitigation for Towed In-Water Devices
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
    <bullet> Towed in-water devices.
    <bullet> Mitigation applies to devices that are towed from a manned
     surface platform or manned aircraft.
    <bullet> 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:
    <bullet> 1 Lookout positioned on the manned towing platform.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 250 yd around marine mammals:
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, maneuver to maintain distance.
------------------------------------------------------------------------

Procedural Mitigation for Small-, Medium-, and Large-Caliber Non-
Explosive Practice Munitions

    Procedural mitigation for small-, medium-, and large-caliber non-
explosive practice munitions is described in Table 60 below.

[[Page 29975]]



 Table 60--Procedural Mitigation for Small-, Medium-, and Large-Caliber
                    Non-Explosive Practice Munitions
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
    <bullet> Gunnery activities using small-, medium-, and large-caliber
     non-explosive practice munitions.
    <bullet> Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned on the platform conducting the
     activity.
    <bullet> 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:
    <bullet> 200 yd around the intended impact location:
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease firing.
        <bullet> 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 non-explosive 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:
    <bullet> Aircraft-deployed non-explosive missiles and rockets.
    <bullet> Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned in an aircraft.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 900 yd around the intended impact location:
        <bullet> 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.
        <bullet> During the activity, observe for marine mammals; if
         resource is observed, cease firing.
        <bullet> 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 non-explosive 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:
    <bullet> Non-explosive bombs.
    <bullet> Non-explosive mine shapes during mine laying activities.
Number of Lookouts and Observation Platform:
    <bullet> 1 Lookout positioned in an aircraft.
Mitigation Zone Size and Mitigation Requirements:
    <bullet> 1,000 yd around the intended target:
        <bullet> 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.
        <bullet> During approach of the target or intended minefield
         location, observe for marine mammals; if resource is observed,
         cease bomb deployment or mine laying.

[[Page 29976]]

 
        <bullet> 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/incidental-take-authorizations-military-readiness-activities. 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):
        <bullet> The Navy will minimize the use of mid-frequency active
         anti-submarine warfare sensor bins MF1 and MF4 to the maximum
         extent practicable.
            <bullet> The Navy will not conduct more than 300 hrs of MF1
             and 20 hrs of MF4 per year.
            <bullet> 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.
        <bullet> The Navy will not use explosives \1\ during training
         and testing.
            <bullet> 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):
        <bullet> The Navy will not use mid-frequency active anti-
         submarine warfare sensor MF1 from November 15-April 15.
            <bullet> 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):
        <bullet> 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):
        <bullet> 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.
            <bullet> 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.
            <bullet> 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:
\1\ Explosive 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).


[[Page 29977]]

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):
        <bullet> The Navy will minimize the use of mid-frequency active
         anti-submarine warfare sensor bin MF1 to the maximum extent
         practicable.
            <bullet> 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.
            <bullet> 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.
        <bullet> The Navy will not use explosives during large-caliber
         gunnery, torpedo, bombing, and missile (including 2.75 in
         rockets) activities during training and testing.
            <bullet> 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):
        <bullet> 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.
        <bullet> 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:
        <bullet> 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.
            <bullet> 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.
            <bullet> 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 (Year-round): 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

[[Page 29978]]

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
------------------------------------------------------------------------
                                              Summary of mitigation
          Stressor or activity                     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-      1,000 yd (large-caliber
 Caliber Projectiles.                     projectiles); 600 yd (medium-
                                          caliber projectiles during
                                          surface-to-surface activities)
                                          or 200 yd (medium-caliber
                                          projectiles during air-to-
                                          surface 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        600 yd (0.1-5 lb net explosive
 Neutralization Activities.               weight) or 2,100 yd (6-650 lb
                                          net explosive weight).
Explosive Mine Neutralization            500 yd (0.1-20 lb net explosive
 Activities Involving Navy Divers.        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--  700 yd.
 Mat Weave and Obstacle Loading.
Maritime Security Operations--Anti-      200 yd.
 Swimmer Grenades.
Vessel Movement........................  500 yd (whales) or 200 yd
                                          (other marine mammals).
Towed In-Water Devices.................  250 yd.
Small-, Medium-, and Large-Caliber Non-  200 yd.
 Explosive Practice Munitions.
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.

[[Page 29979]]



        Table 66--Summary of Mitigation Areas for Marine Mammals
------------------------------------------------------------------------
          Mitigation area            Summary of mitigation requirements
------------------------------------------------------------------------
                   Mitigation Areas for Marine Mammals
------------------------------------------------------------------------
Hawaii Island Mitigation Area       <bullet> The Navy would not exceed
 (Year-round).                       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.
                                       <bullet> 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.
                                    <bullet> The Navy will not use
                                     explosives \1\ during training or
                                     testing activities.
                                       <bullet> 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    <bullet> The Navy will not use mid-
 (November 15-April 15).             frequency active anti-submarine
                                     warfare sensor MF1 during training
                                     or testing activities.
                                    <bullet> 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       <bullet> The Navy would not exceed
 (June 1-October 31).                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.
                                    <bullet> 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.
                                    <bullet> 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.
                                    <bullet> 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     <bullet> The Navy will not use mid-
 Area (Year-round).                  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.
                                    <bullet> 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:
\1\ 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).

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.

[[Page 29980]]

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.navymarinespeciesmonitoring.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:
    <bullet> 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);
    <bullet> 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);
    <bullet> 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);
    <bullet> 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);
    <bullet> An increase in understanding of the effectiveness of 
mitigation and monitoring measures;
    <bullet> A better understanding and record of the manner in which 
the authorized entity complies with the ITA and Incidental Take 
Statement;
    <bullet> 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
    <bullet> 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

[[Page 29981]]

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.navymarinespeciesmonitoring.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:
    <bullet> HRC
    [cir] Long-term Trends in Abundance of Marine Mammals at PMRF;
    [cir] Estimation of Received Levels of Mid-Frequency Active Sonar 
on Marine Mammals at PMRF;
    [cir] Behavioral Response of Marine Mammals to Navy Training and 
Testing at PMRF; and
    [cir] Navy Civilian Marine Mammal Observers on MFAS Ships in 
Offshore Waters of HRC.
    <bullet> SOCAL
    [cir] Blue and Fin Whale Satellite Tagging;
    [cir] Cuvier's Beaked Whale Impact Assessment at the Southern 
California Offshore Antisubmarine Warfare Range (SOAR);
    [cir] Cuvier's Beaked Whale, Blue Whale, and Fin Whale Impact 
Assessments at Non-Instrumented Range Locations in SOCAL; and
    [cir] 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.navymarinespeciesmonitoring.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., population-level 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

[[Page 29982]]

to available data and can be found at: https://www.navymarinespeciesmonitoring.us/regions/pacific/current-projects/.
    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:
    <bullet> Long-term Trends In Abundance Of Marine Mammals At The 
Pacific Missile Range Facility (Hawaii--began in 2015);
    <bullet> Estimation Of Received Levels Of Mid-frequency Active 
Sonar On Marine Mammals At The Pacific Missile Range Facility (Hawaii--
began in 2009);
    <bullet> Behavioral Response Of Marine Mammals To Training And 
Testing At The Pacific Missile Range Facility (Hawaii--began in 2009);
    <bullet> Humpback Whale Satellite Tracking And Genetics (Hawaii, 
Southern California--began in 2017);
    <bullet> Navy Civilian Marine Mammal Observers On Navy Destroyers 
(Hawaii, Southern California began in 2010);
    <bullet> Blue and Fin Whale Satellite Tracking And Genetics 
(Southern California--field work 2014-2017 with ongoing analysis);
    <bullet> Cuvier's Beaked Whale Population Assessment And Impact 
Assessment At Southern California Anti-Submarine Range (Southern 
California--began in 2015);
    <bullet> Cuvier's Beaked Whale Occurrence In Southern California 
From Passive Acoustic Monitoring (Southern California--began in 2012); 
and
    <bullet> 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.navymarinespeciesmonitoring.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/incidental-take-authorizations-military-readiness-activities.

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

[[Page 29983]]

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 non-impulsive 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 sub-reporting in 
these annual reports include:
    <bullet> Humpback Whale Special Reporting Area (December 15-April 
15): The Navy will report the total hours of operation of surface ship 
hull-mounted mid-frequency active sonar used in the special reporting 
area;
    <bullet> 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
    <bullet> 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:
    <bullet> 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
    <bullet> 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., population-
level 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 taxa-specific 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

[[Page 29984]]

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/incidental-take-authorizations-military-
readiness-activities), 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 non-sequential 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 non-impulse 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

[[Page 29985]]

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 activity-
specific, environmental, and species-specific 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 Species-Specific 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 multi-day 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

[[Page 29986]]

and testing 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. 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.

[[Page 29987]]

    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 mid-frequency 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 
free-swimming 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

[[Page 29988]]

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 hull-mounted sources. Hull-mounted anti-submarine 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 high-frequency 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 low-frequency 
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

[[Page 29989]]

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 (N<INF>min</INF>); 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 N<INF>min</INF> 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 deny incidental 
take authorization for

[[Page 29990]]

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 management-related 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

[[Page 29991]]

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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                     Residual
                                              Annual                                        Vessel                   PBR-PBR
                                             proposed                     Fisheries       collisions                  minus                  Recent  UME
                                 Stock       take by       Total      interactions  (Y/     (Y/N);                  annual  M/     Stock       (Y/N);
       Species (stock)         abundance     serious     annual  M/   N);  annual  rate     annual       PBR *        SI and      trend *    number and
                               (Nbest) *    injury or     SI * \2\      of  M/SI from    rate of  M/                  SWFSC         \4\      year (since
                                            mortality                     fisheries        SI from                  authorized                  2007)
                                               \1\                     interactions *       vessel                  take  (%)
                                                                                         collision *                   \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale (CA/OR/WA)........        9,029          0.4        >=2.0  Y; >=2.0..........          1.8           81           78     [uarr]   N
Gray whale (Eastern N              20,990          0.4          132  4.25..............          2.0          624          492     Stable   N
 Pacific).                                                                                                                      since 2003
Humpback whale (CA/OR,WA            1,918          0.4        >=6.5  Y; >=5.3..........          1.0         11.0          4.5     [uarr]   N
 stock or Mexico DPS).
Humpback whale (Central            10,103          0.4           24  Y; 7.4............          4.7           83           59     [uarr]   N
 North Pacific stock or
 Hawaii DPS).
Sperm whale (Hawaiian stock)        3,354          0.4          0.7  0.7...............            0         10.2          9.5          ?   N
Blue whale (Eastern North           1,647          0.2          0.9  0.................          0.9          2.3          1.4     stable   Y; 3, 2007.
 Pacific stock).
Bryde's whale (Eastern            unknown          0.2          0.2  unknown...........          0.2        undet           NA          ?   N
 Tropical Pacific stock).
Bryde's whale (Hawaiian               798          0.2            0  0.................            0          6.3          6.3          ?   N
 stock).
Humpback whale (CA/OR/WA            1,918          0.4        >=6.5  Y; >=5.3..........          1.0         11.0          4.5     [uarr]   N
 stock or Central America
 DPS).
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          519          0.2            0  0.................            0         0.75         0.75          ?   N
 stock).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Presented in the SARS.
\1\ This 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).
\2\ This 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.
\3\ This 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).
\4\ See 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Annual
                                             proposed                     Fisheries                      SWFSC       Residual
                                 Stock       take by       Total      interactions  (Y/                authorized    PBR-PBR       Stock     Recent  UME
       Species (stock)         abundance     serious     annual  M/   N);  annual  rate     PBR *         take        minus       trend *      (Y/N);
                               (Nbest) *    injury or     SI * \2\      of  M/SI from                  (annually)   annual  M/      \5\      number and
                                           mortality *                    fisheries                       \3\         SI and                    year
                                               \1\                     interactions *                               SWFSC \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
California sea lion (U.S.)..      296,750          0.8          385  Y; 331............        9,200          6.6      8,808.4     [uarr]   Y
Short-beaked common dolphin       969,861          1.2         >=40  Y; >=40...........        8,393          2.8      8,350.2          ?   N
 (CA/OR/WA).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Presented in the SARS.
\1\ This 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).

[[Page 29992]]

 
\2\ This 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.
\3\ This column represents annual take authorized for NMFS's SWFSC rulemaking/LOAs (80 FR 58982).
\4\ This 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).
\5\ See 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 short-beaked 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 
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 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

[[Page 29993]]

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 model-estimated 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 (non-
injurious 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 high-frequency 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.

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    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

[[Page 29996]]

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

[[Page 29997]]

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 
na[iuml]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-to-surface 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.
    <bullet> 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.
    [cir] 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.
    [cir] 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.
    [cir] 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.
    [cir] 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.
    <bullet> 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.
    <bullet> 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):
    [cir] 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.
    [cir] 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.
    [cir] 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.
    <bullet> 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

[[Page 29998]]

extent, and severity in certain circumstances, of impacts to 
mysticetes.
    Consequently, the HSTT activities are not expected to adversely 
impact rates of recruitment or survival of any of the stocks of 
mysticete whales (Table 69 and 70 above in this section).

Sperm Whales

    In Table 71 and Table 72 below, for sperm 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 
PTS or tissue damage is anticipated.
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    All takes annually for sperm whales are from Level B harassment 
either behavioral or TTS (Tables 71 and 72 above). Sperm whales are 
listed as endangered under the ESA (both CA/OR/WA and Hawaii stocks) 
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.
    Most Level B harassments to sperm whales and from hull-mounted 
sonar (MF1) in the HSTT Study Area would result from received levels 
between 154 and 166 dB SPL (85 percent). Therefore, 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

[[Page 30000]]

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 far-ranging 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:
    <bullet> 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).
    [cir] 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.
    [cir] 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.
    <bullet> No PTS or injury from acoustic or explosive stressors is 
proposed for authorization or anticipated to occur for sperm whales.
    <bullet> 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):
    [cir] 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.
    [cir] 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.
    <bullet> 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.
    <bullet> 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.
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    Nearly all takes annually for Kogia species are from Level B 
harassment either behavioral or TTS (less than 1 percent PTS) (Tables 
73 and 74 above). No serious injury, or mortalities are anticipated. 
These species are not ESA-listed.
    Most Level B harassments to Kogia spp. from hull-mounted sonar 
(MF1) in the HSTT Study Area would result from received levels between 
154 and 166 dB SPL (85 percent). Therefore, the majority of Level B 
takes are expected to be in the form of milder responses (as compared 
to higher level exposures). 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 as a percentage of 
abundance for Kogia whales are generally between 223 and 249, with 
1,211 for the CA/OR/WA

[[Page 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 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., surface-to-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 Kogia spp. 
through effects on annual rates of recruitment or survival.
    <bullet> No serious injuries or mortalities are proposed for 
authorization or anticipated to occur for Kogia spp.
    <bullet> 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):
    [cir] 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.
    [cir] 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 have a relatively lower likelihood in have 
severe impacts.
    <bullet> 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.
    <bullet> 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.
    <bullet> Kogia spp. are not depleted under the MMPA, nor are they 
listed under the ESA.
    <bullet> 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.
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    Nearly all takes annually for beaked whales from Level B harassment 
are behavioral, less than 1 percent are TTS (Tables 75 and 76 above). 
No PTS, injury, serious injury, or mortalities are anticipated. No 
beaked whales are listed under the ESA.
    Most Level B harassments to beaked whales from hull-mounted sonar 
(MF1) in the HSTT Study Area would result from received levels between 
154 and 160 dB SPL (94 percent). Therefore, 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). 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

[[Page 30006]]

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 [micro]Pa, 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 [micro]Pa (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 1[mu]Pa. 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 [micro]Pa 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

[[Page 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 re-sightings 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., surface-to-
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.
    <bullet> No mortalities of beaked whales are proposed for 
authorization or anticipated to occur.
    <bullet> No PTS or injury of beaked whales from acoustic or 
explosives stressors are proposed for authorization or anticipated to 
occur.
    <bullet> 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):
    [cir] 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.
    [cir] As discussed, the majority of the harassment takes result 
from hull-mounted 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.
    <bullet> 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.
    <bullet> 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

[[Page 30008]]

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 odonotocetes are from Level B 
harassment either behavioral or TTS (less than 1 percent PTS) (Tables 
77 and 78 above). No serious injuries or mortalities are anticipated. 
False killer whales (Main Hawaiian Islands Insular) 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.
    Most Level B harassments to odontocetes from hull-mounted sonar 
(MF1) in the HSTT Study Area would result from received levels between 
154 and 166 dB SPL (85 percent). Therefore, the majority of Level B 
takes are expected to be in the form of milder responses compared to 
higher level exposures). As mentioned earlier in this section, we 
anticipate more severe

[[Page 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, long-beaked 
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 mid-frequency 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, short-finned 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., surface-to-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.
    <bullet> As described in the ``Serious Injury or Mortality'' 
section (Table 68), 1.2 mortalities annually over five years is 
proposed for authorization for short-beaked common dolphin (CA/OR/WA 
stock). The proposed mortality for short-beaked 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.
    <bullet> 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.
    <bullet> 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.
    <bullet> 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):
    [cir] 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.
    [cir] As discussed, the majority of the harassment takes result 
from hull-mounted sonar during MTEs. When

[[Page 30014]]

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.
    <bullet> 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.
    <bullet> The 4-Islands Region Mitigation Area provides partial 
protection for identified biologically important area for dolphin 
species (small and resident populations) by not using mid-frequency 
active anti-submarine warfare sensor MF1.
    <bullet> 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, melon-headed 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.
    <bullet> 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 porpoises are from Level B 
harassment either behavioral or TTS. Less than 1 percent of all takes 
are Level A harassment (PTS) (Table 79 above). No injury (tissue 
damage) serious injury or mortalities are anticipated. Dall's porpoise 
are not listed under the ESA.
    Most Level B harassments to Dall's porpoise from hull-mounted sonar 
(MF1) in the HSTT Study Area would result from received levels between 
154 and 166 dB SPL (85 percent). Therefore, the majority of Level B 
takes are expected to be in the form of milder responses compared to 
higher level exposures. As mentioned earlier in this section, we 
anticipate more severe effects from takes when animals are exposed to 
higher received levels.

[[Page 30016]]

    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 [micro]Pa (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.
    <bullet> 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.
    <bullet> 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.
    <bullet> 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):
    [cir] 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.
    <bullet> 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

[[Page 30017]]

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.
    <bullet> 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 pinnipeds are from Level B harassment 
either behavioral or TTS (less than 1 percent PTS) (Tables 80 and 81 
above). No, injury, serious injury, or mortalities are anticipated. 
Hawaiian monk seal and Guadalupe fur seal 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. The UME for 
Guadalupe fur seal is ongoing. Separately, the UME for California sea 
lions, not an ESA-listed species, will be closed soon.

[[Page 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 non-impulsive 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 non-pulse 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.
    <bullet> 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.
    <bullet> 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.
    <bullet> 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):
    [cir] 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.

[[Page 30020]]

    [cir] As discussed, the majority of the harassment takes result 
from hull-mounted 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.
    <bullet> 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.
    <bullet> 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.
    <bullet> 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

[[Page 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

0
1. The authority citation for part 218 continues to read as follows:

    Authority: 16 U.S.C. 1361 et seq.

0
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 Hawaii-
Southern California Training and Testing (HSTT)


Sec.  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).


Sec.  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].


Sec.  218.72  Permissible methods of taking.

    Under LOAs issued pursuant to Sec.  216.106 of this chapter and 
Sec.  218.77, the Holder of the LOAs (hereinafter ``Navy'') may 
incidentally, but not intentionally, take marine mammals within the 
area described in Sec.  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.


Sec.  218.73  Prohibitions.

    Notwithstanding takings contemplated in Sec.  218.72 and authorized 
by LOAs issued under Sec.  216.106 of this chapter and Sec.  218.76, no 
person in connection with the activities described in Sec.  218.72 may:
    (a) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or an LOA issued under Sec.  216.106 of 
this chapter and Sec.  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.


Sec.  218.74  Mitigation requirements.

    When conducting the activities identified in Sec.  218.70(c), the 
mitigation measures contained in any LOAs issued under Sec.  216.106 of 
this chapter and Sec.  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 large-caliber 
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,

[[Page 30022]]

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 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 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) Hull-mounted 
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 hull-mounted 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

[[Page 30023]]

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 medium-caliber 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-to-surface activities using explosive 
medium-caliber projectiles,
    (B) 600 yd around the intended impact location for surface-to-
surface activities using explosive medium-caliber 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

[[Page 30024]]

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.

[[Page 30025]]

    (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 
time-delay 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.

[[Page 30026]]

    (18) Small-, Medium-, and Large-Caliber 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 non-
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--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 
non-explosive 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 
(year-round):
    (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

[[Page 30027]]

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 
mid-frequency 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]


Sec.  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 Sec.  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.navymarinespeciesmonitoring.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

[[Page 30028]]

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.


Sec.  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 Sec.  216.106 of this 
subpart, conducting the activity identified in Sec.  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 Sec.  218.77(c)(1)) required by an 
LOA, the Navy must apply for and obtain a modification of LOAs as 
described in Sec.  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.


Sec.  218.77  Renewals and modifications of Letters of Authorization.

    (a) An LOA issued under Sec.  216.106 of this subchapter and Sec.  
218.76 for the activity identified in Sec.  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 Sec.  216.106 of this subchapter and Sec.  
218.76 for the activity identified in Sec.  218.70(c) may be modified 
by NMFS under the following circumstances:
    (1) Adaptive Management--After consulting with the Navy regarding 
the

[[Page 30029]]

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 Sec.  216.106 of 
this chapter and Sec.  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.


Sec. Sec.  218.78-218.79  [Reserved]

[FR Doc. 2018-13115 Filed 6-25-18; 8:45 am]
 BILLING CODE 3510-22-P