Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Mariana Islands Training and Testing (MITT) Study Area, 5782-5901 [2020-00481]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 85, Number 21 (Friday, January 31, 2020)]
[Proposed Rules]
[Pages 5782-5901]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-00481]



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Vol. 85

Friday,

No. 21

January 31, 2020

Part II





Department of Commerce





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National Oceanic and Atmospheric Administration





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50 CFR Parts 218





Taking and Importing Marine Mammals; Taking Marine Mammals Incidental 
to the U.S. Navy Training and Testing Activities in the Mariana Islands 
Training and Testing (MITT) Study Area; Proposed Rule

Federal Register / Vol. 85, No. 21 / Friday, January 31, 2020 / 
Proposed Rules

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 218

[Docket No. 200109-0005]
RIN 0648-BJ00


Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to the U.S. Navy Training and Testing Activities in the 
Mariana Islands Training and Testing (MITT) 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) to take 
marine mammals incidental to training and testing activities conducted 
in the Mariana Islands Training and Testing (MITT) Study Area. Pursuant 
to the MMPA, NMFS is requesting comments on its proposal to issue 
regulations and subsequent Letter 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 LOA. Agency 
responses to public comments will be summarized in the notice of the 
final decision. 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 March 
16, 2020.

ADDRESSES: You may submit comments on this document, identified by 
NOAA-NMFS-2020-0006, by any of the following methods:
     Electronic submission: Submit all electronic public 
comments via the Federal e-Rulemaking Portal. Go to 
www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2020-0006, click the 
``Comment Now!'' icon, complete the required fields, and enter or 
attach your comments.
     Mail: Submit written 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.
    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), confidential business information, 
or otherwise sensitive information submitted voluntarily by the sender 
will be publicly accessible. 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.
    A copy of the Navy's application, NMFS' proposed and final rules 
and subsequent LOA for the existing regulations, and other supporting 
documents and documents cited herein 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 use the contact listed here (see FOR 
FURTHER INFORMATION CONTACT).

FOR FURTHER INFORMATION CONTACT: Stephanie Egger, Office of Protected 
Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Purpose of Regulatory Action

    These proposed regulations, issued under the authority of the MMPA 
(16 U.S.C. 1361 et seq.), would provide the framework for authorizing 
the take of marine mammals incidental to the Navy's training and 
testing activities (which qualify as military readiness activities) 
from the use of sonar and other transducers and in-water detonations 
throughout the MITT Study Area. The Study Area includes the seas off 
the coasts of Guam and the Commonwealth of the Northern Mariana Islands 
(CNMI), the in-water areas around the Mariana Islands Range Complex 
(MIRC), the transit corridor between the MIRC and the Hawaii Range 
Complex (HRC), and select pierside and harbor locations. The transit 
corridor is outside the geographic boundaries of the MIRC and 
represents a great circle route across the high seas for Navy vessels 
transiting between the MIRC and the HRC. The proposed activities also 
include various activities in Apra Harbor such as sonar maintenance 
alongside Navy piers located in Inner Apra Harbor.
    NMFS received an application from the Navy requesting seven-year 
regulations and an authorization to incidentally take individuals of 
multiple species of marine mammals (``Navy's rulemaking/LOA 
application'' or ``Navy's application''). Take is anticipated to occur 
by Level A and Level B harassment incidental to the Navy's training and 
testing activities, with no serious injury or mortality expected or 
proposed for authorization.

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA 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, the public is provided with notice of the 
proposed incidental take authorization and provided the opportunity to 
review and 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 
stocks and will not have an unmitigable adverse impact on the 
availability of the species or stocks for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other means of effecting the least practicable adverse 
impact on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such species or stocks for 
taking for certain subsistence uses (referred to in this rule as 
``mitigation measures''); and requirements pertaining to the monitoring 
and reporting of such takings. The MMPA defines ``take'' to mean to 
harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or 
kill any marine mammal. The Preliminary Analysis and Negligible Impact 
Determination section below discusses the definition of ``negligible 
impact.''
    The NDAA for Fiscal Year 2004 (2004 NDAA) (Pub. L. 108-136) amended 
section 101(a)(5) of the MMPA to remove the ``small numbers'' and 
``specified geographical region'' provisions indicated above and 
amended the definition of ``harassment'' as applied to a ``military 
readiness activity.'' The definition of harassment for military 
readiness activities (section 3(18)(B) of the MMPA) is (i) Any act that 
injures or has the significant potential to

[[Page 5783]]

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). In addition, the 2004 NDAA amended the 
MMPA as it relates to military readiness activities such that the least 
practicable adverse impact analysis shall include consideration of 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    More recently, section 316 of the NDAA for Fiscal Year 2019 (2019 
NDAA) (Pub. L. 115-232), signed on August 13, 2018, amended the MMPA to 
allow incidental take rules for military readiness activities under 
section 101(a)(5)(A) to be issued for up to seven years. Prior to this 
amendment, all incidental take rules under section 101(a)(5)(A) were 
limited to five years.

Summary and Background of Request

    On February 11, 2019, NMFS received an application from the Navy 
for authorization to take marine mammals by Level A and Level B 
harassment incidental to training and testing activities (categorized 
as military readiness activities) from the use of sonar and other 
transducers and in-water detonations in the MITT Study Area over a 
seven-year period beginning when the current authorization expires.
    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 regulations and LOA (if 
authorized): Amphibious warfare (in-water detonations), anti-submarine 
warfare (sonar and other transducers, in-water detonations), surface 
warfare (in-water detonations), and other testing and training (sonar 
and other transducers). The activities would not include any pile 
driving/removal or use of air guns.
    This will be the third time NMFS has promulgated incidental take 
regulations pursuant to the MMPA relating to similar military readiness 
activities in the MITT Study Area, following those effective from 
August 3, 2010, through August 3, 2015 (75 FR 45527; August 3, 2010) 
and from August 3, 2015 through August 3, 2020 (80 FR 46112; August 3, 
2015). 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.
    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. 8062), which requires 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 
operations. The Navy's testing activities ensure naval forces are 
equipped with well-maintained systems that take advantage of the latest 
technological advances. The Navy's research and acquisition community 
conducts military readiness activities that involve testing. The Navy 
tests ships, aircraft, weapons, combat systems, sensors, and related 
equipment, and conducts scientific research activities to achieve and 
maintain military readiness.
    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 (e.g., 
organization of ships, submarines, aircraft, 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 MITT 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. These proposed regulations would cover training 
and testing activities that would occur for a seven-year period 
following the expiration of the current MMPA authorization for the MITT 
Study Area, which expires on August 3, 2020.

Description of the Specified Activity

    The Navy requests authorization to take marine mammals incidental 
to conducting training and testing activities. The Navy has determined 
that acoustic and explosive stressors are most likely to result in 
impacts on marine mammals that could rise to the level of harassment, 
and NMFS concurs with this determination. Detailed descriptions of 
these activities are provided in Chapter 2 of the 2019 MITT Draft 
Supplemental Environmental Impact Statement (SEIS)/Overseas EIS (OEIS) 
(MITT DSEIS/OEIS) and in the Navy's rule making/LOA application 
(https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities) and are 
summarized here.

Dates and Duration

    The specified activities would occur at any time during the seven-
year period of validity of the regulations. The proposed number of 
training and testing activities are described in the Detailed 
Description of the Specified Activities section (Tables 1 through 5).

Geographical Region

    The MITT Study Area is comprised of three components: (1) The MIRC, 
(2) additional areas on the high seas, and (3) a transit corridor 
between the MIRC and the HRC as depicted in Figure 1 below. The MIRC 
includes the waters south of Guam to north of Pagan (CNMI), and from 
the Pacific Ocean east of the Mariana Islands to the Philippine Sea to 
the west, encompassing 501,873 square nautical miles (NM\2\) of open 
ocean (Figure 1). For the additional areas of the high seas, this 
includes the area to the north of the MIRC that is within the U.S. 
Exclusive Economic Zone (EEZ) of the CNMI and the areas to the west of 
the MIRC. The transit corridor is outside the geographic boundaries of 
the MIRC and represents a great circle route (i.e., the shortest 
distance) across the high seas for Navy ships transiting between the 
MIRC and the HRC. Although not part of any defined range complex, the 
transit corridor is important to the Navy in that it provides available 
air, sea, and undersea space where vessels and aircraft conduct 
training and testing while in transit. While in transit and along the 
corridor, vessels and aircraft would, at times, conduct basic and 
routine unit-level activities such as gunnery and sonar training. Ships 
also conduct sonar maintenance, which includes active sonar 
transmissions.
BILLING CODE 3510-22-P

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[GRAPHIC] [TIFF OMITTED] TP31JA20.001

BILLING CODE 3510-22-C
    Training and testing activities occur within the MITT Study Area, 
which is composed of a designated set of specifically bounded 
geographic areas encompassing a water component (above and below the 
surface), airspace, and for training a land component, such as Farallon 
de Medinilla (FDM). The MIRC includes established OPAREAs and special 
use airspace, which may be further divided to provide safety and better 
control of the area and activities being conducted.
    The MIRC includes approximately 40,000 NM \2\ of special use 
airspace. This airspace is almost entirely over the ocean (except W13A) 
and includes warning areas, and restricted areas (R) (see the MITT 
Draft SEIS/OEIS, Figure 2.1-2 and Figure 2.1-3, for details). Warning 
Areas (W)-517 and W-12 include approximately 11,800 NM\2\ of special 
use airspace; W-11 (A/B) is approximately 10,500 NM\2\ of special use 
airspace, and W-13 (A/B/C) is approximately 18,000 NM\2\ of special use 
airspace. The restricted area airspace over or near land areas within 
the MIRC includes approximately 2,463 NM\2\ of special use airspace and 
restricted areas (R) 7201 and R7201A, which extends in a 12 NM radius 
around FDM.
    The MIRC includes the sea and undersea space from the ocean surface 
to the ocean floor. The MIRC also consists of designated sea and 
undersea space training areas, which include designated drop zones; 
underwater demolition and floating mine exclusion zones; danger zones 
associated with live-fire ranges; and training areas associated with 
military controlled beaches, harbors, and littoral areas.
    Additionally, the MITT Study Area includes pierside locations in 
the Apra Harbor Naval Complex where surface ship and submarine sonar 
maintenance and testing occur. Activities in Apra Harbor include 
channels and routes to and from the Navy port in the Apra Harbor Naval 
Complex, and associated wharves and facilities within the Navy port.

Primary Mission Areas

    The Navy categorizes its at-sea activities into functional warfare 
areas called primary mission areas. These activities generally fall 
into the following eight primary mission areas: Air warfare; amphibious 
warfare; anti-submarine warfare (ASW); electronic warfare; 
expeditionary warfare; mine warfare (MIW); strike warfare; and surface 
warfare (SUW). Most activities

[[Page 5785]]

addressed in the MITT Study Area are categorized under one of the 
primary mission areas. Activities that do not fall within one of these 
areas are listed as ``other activities.'' Each warfare community 
(surface, subsurface, aviation, and expeditionary 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. A description of the sonar, munitions, targets, 
systems, and other material used during training and testing activities 
within these primary mission areas is provided in the 2019 MITT DSEIS/
OEIS Appendix A (Training and Testing Activities Descriptions).
    The Navy describes and analyzes the effects of its activities 
within the 2019 MITT DSEIS/OEIS (U.S. Department of the Navy, 2019). In 
its assessment, the Navy concluded that sonar and other transducers and 
in-water detonations were the stressors that would result in impacts on 
marine mammals that could rise to the level of harassment as defined 
under the MMPA. Therefore, the Navy's rulemaking/LOA application 
provides the Navy's assessment of potential effects from these 
stressors in terms of the various warfare mission areas in which they 
would be conducted. Those mission areas include the following:

[ssquf] Amphibious warfare (underwater detonations)
[ssquf] ASW (sonar and other transducers, underwater detonations)
[ssquf] MIW (sonar and other transducers, underwater detonations)
[ssquf] SUW (underwater detonations)
[ssquf] Other training and testing activities (sonar and other 
transducers)

    The Navy's training and testing activities in air warfare, 
electronic warfare, and expeditionary warfare do not involve sonar and 
other transducers, underwater detonations, or any other stressors that 
could result in harassment, serious injury, or mortality of marine 
mammals. Therefore, the activities in air, electronic, and 
expeditionary warfare areas are not discussed further in this proposed 
rule, but are analyzed fully in the Navy's 2019 MITT DSEIS/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 spans 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 are often integrated into 
training activities and, in most cases, the systems are used in the 
same manner in which they are used for 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.
ASW
    The mission of anti-submarine warfare is to locate, neutralize, and 
defeat hostile submarine forces that threaten Navy surface forces. 
Anti-submarine warfare can involve various assets such as aircraft, 
ships, and submarines, which 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.
    Anti-submarine warfare 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 
anti-submarine warfare from detecting and tracking a submarine to 
attacking a target using either exercise torpedoes (i.e., torpedoes 
that do not contain an explosive warhead) or simulated weapons. These 
integrated anti-submarine warfare training exercises are conducted in 
coordinated, at-sea training events involving submarines, ships, and 
aircraft.
    Testing of anti-submarine warfare 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 
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 personnel in 
the use of new or newly enhanced systems during a large scale, complex 
exercise.
MIW
    The mission of mine warfare 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. Mine warfare also 
includes training and testing in offensive mine laying. Naval mines can 
be laid by ships, submarines, or aircraft.
    Mine warfare 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 mine warfare 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. Mine warfare testing and development fall into two 
primary categories: Mine detection and classification, and mine 
countermeasure and neutralization testing. Mine detection and 
classification testing involves the use of air, surface, and subsurface 
vessels and uses sonar, including towed and side scan 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

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of air, surface, and subsurface units and uses tracking devices and 
countermeasure and neutralization systems to evaluate the effectiveness 
of neutralizing mine threats. Most neutralization tests use mine 
shapes, or non-explosive practice mines, to accomplish the requirements 
of the activity. 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.
    Most training and testing activities use mine shapes, or non-
explosive practice mines, to accomplish the requirements of the 
activity. A small percentage of mine warfare activities require the use 
of high-explosive mines to evaluate and confirm the ability of the 
system or the crews conducting the training to neutralize a high-
explosive mine under operational conditions. The majority of mine 
warfare systems are deployed by ships, helicopters, and unmanned 
vehicles. Tests may also be conducted in support of scientific research 
to support these new technologies.
SUW
    The mission of surface warfare is to obtain control of sea space 
from which naval forces may operate, which entails offensive action 
against surface targets while also defending against aggressive actions 
by enemy forces. In the conduct of surface warfare, aircraft use guns, 
air-launched cruise missiles, or other precision-guided munitions; 
ships employ naval guns and surface-to-surface missiles; and submarines 
attack surface ships using torpedoes or submarine-launched, anti-ship 
cruise missiles.
    Surface warfare training includes surface-to-surface gunnery and 
missile exercises, air-to-surface gunnery and missile exercises, 
submarine missile or torpedo launch activities, and other munitions 
against surface targets.
    Testing of weapons used in surface warfare 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 activities 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 training 
activities.
Other Activities
    Naval forces conduct additional training, testing and maintenance 
activities that do not fit into the primary mission areas that are 
listed above. The 2019 MITT DSEIS/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 acoustic and oceanographic research. These activities 
include the use of various sonar systems.

Overview of Major Training Activities and Exercises Within the MITT 
Study Area

    A major training exercise (MTE) for purposes of this rulemaking is 
comprised of several unit-level activities conducted by several units 
operating together, commanded and controlled by a single Commander, and 
typically generating more than 100 hours of active sonar. These 
exercises typically employ an exercise scenario developed to train and 
evaluate the exercise participants in tactical and operational tasks. 
In an MTE, most of the activities being directed and coordinated by the 
Commander in charge of the exercise 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.
    Exercises may also be categorized as integrated or coordinated ASW 
exercises. The distinction between integrated and coordinated ASW 
exercises is how the units are being controlled. Integrated ASW 
exercises are controlled by an existing command structure, and 
generally occur during the Integrated Phase of the training cycle. 
Coordinated exercises may have a command structure stood up solely for 
the event; for example, the commanding officer of a ship may be placed 
in tactical command of other ships for the duration of the exercise. 
Not all integrated ASW exercises are considered MTEs, due to their 
scale, number of participants, duration, and amount of active sonar. 
The distinction between large, medium, and small integrated or 
coordinated exercises is based on the scale of the exercise (i.e., 
number of ASW units participating), the length of the exercise, and the 
total number of active sonar hours. 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 MITT Study Area

    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 (missiles, radar, and sonar) and platforms 
(surface ships, submarines, and aircraft); and acquisition of systems 
and platforms. The individual commands within the research and 
acquisition community include Naval Air Systems Command, Naval Sea 
Systems Command, and Office of Naval Research.
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 following subsections describe the acoustic 
and explosive stressors for marine mammals and their habitat (including 
prey species) within the MITT Study Area. Because of the complexity of 
analyzing sound propagation in the ocean environment, the Navy relies 
on acoustic models in its environmental analyses and rulemaking/LOA 
application that consider sound source characteristics and varying 
ocean conditions across the MITT Study Area. Stressor/resource 
interactions that were determined to have de minimis or no impacts 
(i.e., vessel, aircraft, or weapons noise, and explosions in air) were 
not carried forward for analysis in the Navy's rulemaking/LOA 
application. NMFS reviewed the Navy's analysis and conclusions on de 
minimis sources and finds them complete and supportable.

Acoustic Stressors

    Acoustic stressors include acoustic signals emitted into the water 
for a specific purpose, such as sonar and other transducers (devices 
that convert energy from one form to another--in this case, into sound 
waves), as well as incidental sources of broadband sound produced as a 
byproduct of vessel movement and use of weapons or other deployed 
objects. 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

[[Page 5787]]

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 sonar and other transducers 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 vessel or aircraft transits, weapons 
firing, and bow shocks.
    The use of source classification bins provides the following 
benefits:
    [ssquf] 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;''
    [ssquf] Improves efficiency of source utilization data collection 
and reporting requirements anticipated under the MMPA authorizations;
    [ssquf] 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;
    [ssquf] Allows analyses to be conducted in a more efficient manner, 
without any compromise of analytical results; and
    [ssquf] 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, navigate safely, 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 this proposed rule, the terms 
sonar and other transducers will be 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 (greater than 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 
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.
    The sound sources and platforms typically used in naval activities 
analyzed in the Navy's rulemaking/LOA application are described in 
Appendix A (Training and Testing Activities Descriptions) of the 2019 
MITT DSEIS/OEIS. The effects of these factors are explained in Appendix 
H (Acoustic and Explosive Concepts) of the MITT 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.
ASW
    Sonar used during ASW training and testing would impart the 
greatest amount of acoustic energy of any category of sonar and other 
transducers analyzed in this proposed rule. Types of sonars used to 
detect vessels include hull-mounted, towed, line array, sonobuoy, 
helicopter dipping, and torpedo sonars. In addition, acoustic targets 
and torpedo 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 can vary widely, from rarely 
used to continuously active. The beam pattern 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 beyond 12 NM from shore. Exceptions 
include use of dipping sonar by helicopters, maintenance of systems 
while in Apra Harbor, and system checks while transiting to or from 
Apra Harbor.
Mine Warfare, Small Object Detection and Imaging
    Sonars used to locate mines and other small objects, similar to 
those used in imaging, are typically high frequency or very high 
frequency. Higher frequencies allow for greater resolution and, 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. Hull-mounted anti-submarine 
sonars can also be used in an object detection mode known as 
``Kingfisher'' mode. 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 MITT Study Area.
    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 training and testing minefields, temporary 
minefields close to strategic ports and harbors, or at targets of 
opportunity such as navigation buoys.
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 
MITT Study Area. These

[[Page 5788]]

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. As detailed 
below, 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. Unless stated otherwise, a reference distance 
of 1 meter (m) is used for sonar and other transducers.
    [ssquf] 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;
    [ssquf] 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;
    [ssquf] 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 MITT Study Area are shown in Table 1 
below. While general parameters or source characteristics are shown in 
the table, actual source parameters are classified.

Table 1--Sonar and Transducers Quantitatively Analyzed in the MITT Study
                                  Area
------------------------------------------------------------------------
     Source class category             Bin              Description
------------------------------------------------------------------------
Low-Frequency (LF): Sources      LF4              LF sources equal to
 that produce signals less than  LF5               180 dB and up to 200
 1 kHz.                                            dB.
                                                  LF sources less than
                                                   180 dB.
Mid-Frequency (MF): Tactical     MF1              Hull-mounted surface
 and non-tactical sources that   MF1K              ship sonars (e.g., AN/
 produce signals between 1 and   MF3               SQS-53C and AN/SQS-
 10 kHz.                                           60).
                                                  Kingfisher mode
                                                   associated with MF1
                                                   sonars.
                                                  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              Underwater sound
                                                   signal devices (e.g.,
                                                   MK 84 SUS).
                                 MF9              Sources (equal to 180
                                                   dB and up to 200 dB)
                                                   not otherwise binned.
                                 MF11             Hull-mounted surface
                                                   ship sonars with an
                                                   active duty cycle
                                                   greater than 80
                                                   percent.
                                 MF12             Towed array surface
                                                   ship sonars with an
                                                   active duty cycle
                                                   greater than 80
                                                   percent.
High-Frequency (HF): Tactical    HF1              Hull-mounted submarine
 and non-tactical sources that   HF3               sonars (e.g., AN/BQQ-
 produce signals between 10 and  HF4               10).
 100 kHz.                                         Other hull-mounted
                                                   submarine sonars
                                                   (classified).
                                                  Mine detection,
                                                   classification, and
                                                   neutralization sonar
                                                   (e.g., AN/SQS-20).
                                 HF6              Sources (equal to 180
                                                   dB and up to 200 dB)
                                                   not otherwise binned.
Anti-Submarine Warfare (ASW):    ASW1             MF systems operating
 Tactical sources (e.g., active  ASW2              above 200 dB.
 sonobuoys and acoustic          ASW3             MF Multistatic Active
 countermeasures systems) used   ASW4              Coherent sonobuoy
 during ASW training and         ASW5              (e.g., AN/SSQ-125).
 testing activities.                              MF towed active
                                                   acoustic
                                                   countermeasure
                                                   systems (e.g., AN/SLQ-
                                                   25).
                                                  MF expendable active
                                                   acoustic device
                                                   countermeasures
                                                   (e.g., MK 3).
                                                  MF sonobuoys with high
                                                   duty cycles.
Torpedoes (TORP): Active         TORP1            Lightweight torpedo
 acoustic signals produced by    TORP2             (e.g., MK 46, MK 54,
 torpedoes.                      TORP3             or Anti-Torpedo
                                                   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): Sources     M3               MF acoustic modems
 used to transmit data.                            (greater than 190
                                                   dB).
Synthetic Aperture Sonars        SAS2             HF SAS systems.
 (SAS): Sonars used to form      SAS4             MF to HF broadband
 high-resolution images of the                     mine countermeasure
 seafloor.                                         sonar.
------------------------------------------------------------------------

Explosive Stressors

    This section describes the characteristics of explosions during 
naval training and testing. The activities analyzed in Navy's 
rulemaking/LOA application that use explosives are described in 
Appendix A (Training and Testing Activities Descriptions) of the 2019 
MITT DSEIS/OEIS. Explanations of the terminology and metrics used when 
describing explosives in the Navy's rule making/LOA application are 
also in Appendix H (Acoustic and Explosive Concepts) of the 2019 MITT 
DSEIS/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 in 
the warhead, the type of explosive material, the boundaries and 
characteristics of the propagation medium, and, in water, the 
detonation depth and the depth of the receiver (i.e., marine mammal). 
The net

[[Page 5789]]

explosive weight, which is 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 
H (Acoustic and Explosive Concepts) of the 2019 MITT DSEIS/OEIS.
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 NM from shore, 
with the exception of three existing mine warfare areas (Outer Apra 
Harbor, Piti, and Agat Bay). Nearshore small explosive charges only 
occur at the three mine warfare areas. Piti and Agat Bay, while 
nearshore, are in very deep water and used for floating mine 
neutralization activities. 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 discussed above and 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 MITT Study Area 
are shown in Table 2 below.

                               Table 2--Explosives Analyzed in the MITT Study Area
----------------------------------------------------------------------------------------------------------------
                             Net explosive
            Bin               weight (lb)       Example explosive source       Modeled detonation depths (ft)
----------------------------------------------------------------------------------------------------------------
E1........................         0.1-0.25  Medium-caliber projectiles...  0.3, 60.
E2........................        >0.25-0.5  Anti-swimmer grenade.........  0.3.
E3........................         >0.5-2.5  57 mm projectile.............  0.3, 60.
E4........................           >2.5-5  Mine neutralization charge...  33, 197.
E5........................            >5-10  5 in projectiles.............  0.3, 10, 98.
E6........................           >10-20  Hellfire missile.............  0.3, 98.
E8........................          >60-100  250 lb. bomb; Lightweight      0.3, 150.
                                              torpedo.
E9........................         >100-250  500 lb bomb..................  0.3.
E10.......................         >250-500  1,000 lb bomb................  0.3.
E11.......................         >500-650  Heavyweight torpedo..........  150, 300.
E12.......................       >650-1,000  2,000 lb bomb................  0.3.
----------------------------------------------------------------------------------------------------------------
Notes: (1) Net Explosive Weight refers to the equivalent amount of TNT. The actual weight of a munition may be
  larger due to other components; (2) in = inch(es), lb = pound(s), ft = feet.

    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 H (Acoustic and Explosive Concepts) of the 2019 MITT DSEIS/
OEIS explains the characteristics of explosive detonations and how the 
above factors affect the propagation of explosive energy in the water.
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 thresholds for 
assessing the likelihood of harassment from a blast, which are also 
used to inform mitigation zones, are assumed to encompass risk due to 
fragmentation.

Other Stressor--Vessel Strike

    NMFS also considered the chance that a vessel utilized in training 
or testing activities could strike a marine mammal. 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 are a limited, sporadic, and incidental 
result of Navy vessel movement within a 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 both the potential likelihood and 
impacts of a vessel strike to marine mammals (Conn and Silber, 2013; 
Gende et al., 2011; Silber et al., 2010; Vanderlaan and Taggart, 2007; 
Wiley et al., 2016). For large vessels,

[[Page 5790]]

speed and angle of approach can influence the severity of a strike.
    Navy vessels transit at speeds that are optimal for fuel 
conservation and to meet training and testing requirements. Vessels 
used as part of the proposed 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). 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 to 13 kn, while a few specialized vessels can 
travel at faster speeds. Small craft (for purposes of this analysis, 
less than 18 m in length) have much more variable speeds (0 to 50+ kn, 
dependent on the activity), but generally range from 10 to 14 kn. From 
unpublished Navy data, average median speed for large Navy ships in the 
other Navy ranges from 2011-2015 varied from 5 to 10 kn with variations 
by ship class and location (i.e., slower speeds close to the coast). 
Similar patterns would occur in the MITT Study Area. A full description 
of Navy vessels that are used during training and testing activities 
can be found in Chapter 2 (Description of Proposed Action and 
Alternatives) of the 2019 MITT DSEIS/OEIS.
    While these speeds are representative of most events, some vessels 
need to temporarily 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.
    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.

Detailed Description of the Specified Activities

Proposed Training and Testing Activities

    The Navy's Operational Commands and various System Commands have 
identified activity levels that are needed in the MITT Study Area to 
ensure naval forces have sufficient training, maintenance, and new 
technology to meet Navy missions in the Pacific. Training prepares Navy 
personnel to be proficient in safely operating and maintaining 
equipment, weapons, and systems to conduct assigned missions. Navy 
research develops new science and technology followed by concept 
testing relevant to future Navy needs. Unlike other Navy range 
complexes, training and testing in the MITT Study Area is more episodic 
as transiting strike groups or individual units travel through on the 
way to and from the Western Pacific, or forward deployed assets 
temporarily travel to the MITT Study Area for individual or group 
activities. This section analyzes a maximum number of activities that 
could occur each year and then a maximum total of activities that could 
occur for seven years. One activity, Torpedo (Explosive) Testing, does 
not occur every year, but the maximum times it could occur over one 
year and seven years was analyzed.
    The training and testing activities that the Navy proposes to 
conduct in the MITT Study Area are summarized in Table 3. The table is 
organized according to primary mission areas and includes the activity 
name, associated stressors of Navy's activities, description of the 
activity, sound source bin, the locations of those activities in the 
MITT 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 (Training and Testing Activities Descriptions) of 
the 2019 MITT DSEIS/OEIS.

                         Table 3--Proposed Training and Testing Activities Analyzed for Seven-Year Period in the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Typical duration of                                         Annual #   7-Year #
   Stressor category         Activity              Description                  event           Source bin \1\        Location      of events  of events
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                      Major Training Event--Large Integrated Anti-Submarine Warfare Training (ASW)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic..............  Joint Multi-       Typically a 10-day Joint     10 days.............  ASW2, ASW3, ASW4,  Study Area; MIRC.          1          4
                         Strike Group       exercise, in which up to                           HF1, MF1, MF11,
                         Exercise.          three carrier strike                               MF3, MF4, MF5,
                                            groups would conduct                               MF12, TORP1.
                                            training exercises
                                            simultaneously.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Major Training Event--Medium Integrated ASW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic..............  Joint              Typically a 10-day exercise  10 days.............  ASW2, ASW3, MF1,   Study Area; Apra           1          7
                         Expeditionary      that could include a                               MF4, MF5, MF12.    Harbor.
                         Exercise.          Carrier Strike Group and
                                            Expeditionary Strike
                                            Group, Marine
                                            Expeditionary Units, Army
                                            Infantry Units, and Air
                                            Force aircraft together in
                                            a joint environment that
                                            includes planning and
                                            execution efforts as well
                                            as military training
                                            activities at sea, in the
                                            air, and ashore.
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 5791]]

 
                                                                 Medium Coordinated ASW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic..............  Marine Air Ground  Typically a 10-day exercise  10 days.............  ASW3, MF1, MF4,    Study Area to              4         28
                         Task Force         that conducts over the                             MF12.              nearshore; MIRC;
                         Exercise           horizon, ship to objective                                            Tinian; Guam;
                         (Amphibious)--Ba   maneuver for the elements                                             Rota; Saipan;
                         ttalion.           of the Expeditionary                                                  FDM.
                                            Strike Group and the
                                            Amphibious Marine Air
                                            Ground Task Force. The
                                            exercise utilizes all
                                            elements of the Marine Air
                                            Ground Task Force
                                            (Amphibious), conducting
                                            training activities ashore
                                            with logistic support of
                                            the Expeditionary Strike
                                            Group and conducting
                                            amphibious landings.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                           ASW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic..............  Tracking           Helicopter crews search      2-4 hours...........  MF4, MF5.........  Study Area > 3 NM         10         70
                         Exercise--Helico   for, detect, and track                                                from land;
                         pter (TRACKEX--    submarines.                                                           Transit Corridor.
                         Helo).
Acoustic..............  Torpedo Exercise-- Helicopter crews search      2-5 hours...........  MF4, MF5, TORP1..  Study Area > 3 NM          6         42
                         Helicopter         for, detect, and track                                                from land.
                         (TORPEX--Helo).    submarines. Recoverable
                                            air launched torpedoes are
                                            employed against submarine
                                            targets.
Acoustic..............  Tracking           Maritime patrol aircraft     2-8 hours...........  MF5..............  Study Area > 3 NM         36        252
                         Exercise--Mariti   crews search for, detect,                                             from land.
                         me Patrol          and track submarines.
                         Aircraft
                         (TRACKEX--Mariti
                         me Patrol
                         Aircraft).
Acoustic..............  Torpedo Exercise-- Maritime patrol aircraft     2-8 hours...........  MF5, TORP1.......  Study Area > 3 NM          6         42
                         Maritime Patrol    crews search for, detect,                                             from land.
                         Aircraft           and track submarines.
                         (TORPEX--Maritim   Recoverable air launched
                         e Patrol           torpedoes are employed
                         Aircraft).         against submarine targets.
Acoustic..............  Tracking           Surface ship crews search    2-4 hours...........  ASW1, ASW3, MF1,   Study Area > 3 NM         91        637
                         Exercise--Surfac   for, detect, and track                             MF11, MF12.        from land.
                         e (TRACKEX--       submarines.
                         Surface).
Acoustic..............  Torpedo Exercise-- Surface ship crews search    2-5 hours...........  ASW3, MF1, MF5,    Study Area > 3 NM          6         42
                         Surface (TORPEX--  for, detect, and track                             TORP1.             from land.
                         Surface).          submarines. Exercise
                                            torpedoes are used during
                                            this event.
Acoustic..............  Tracking           Submarine crews search for,  8 hours.............  ASW4, HF1, HF3,    Study Area > 3 NM          4         28
                         Exercise--Submar   detect, and track                                  MF3.               from land;
                         ine (TRACKEX--     submarines.                                                           Transit Corridor.
                         Sub).
Acoustic..............  Torpedo Exercise-- Submarine crews search for,  8 hours.............  ASW4, HF1, MF3,    Study Area > 3 NM          9         63
                         Submarine          detect, and track                                  TORP2.             from land.
                         (TORPEX--Sub).     submarines. Recoverable
                                            exercise torpedoes are
                                            used during this event.
Acoustic..............  Small Joint        Typically, a 5-day exercise  5 days..............  ASW2, ASW3, ASW4,  Study Area > 3 NM          3         21
                         Coordinated ASW    with multiple ships,                               HF1, MF1, MF3,     from land.
                         exercise (Multi-   aircraft and submarines                            MF4, MF5, MF11,
                         Sail/GUAMEX).      integrating the use of                             MF12.
                                            their sensors, including
                                            sonobuoys, to search,
                                            detect, and track threat
                                            submarines.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Mine Warfare
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic..............  Civilian Port      Maritime security personnel  Multiple days.......  HF4, SAS2........  MIRC, Mariana              1          7
                         Defense.           train to protect civilian                                             littorals, Inner
                                            ports and harbors against                                             and Outer Apra
                                            enemy efforts to interfere                                            Harbor.
                                            with access to those
                                            ports.

[[Page 5792]]

 
Explosive.............  Mine               Ship, small boat, and        1-4 hours...........  E4...............  Study Area,                4         28
                         Neutralization--   helicopter crews locate                                               Mariana
                         Remotely           and disable mines using                                               littorals, and
                         Operated Vehicle   remotely operated                                                     Outer Apra
                         Sonar (ASQ-235     underwater vehicles                                                   Harbor.
                         [AQS-20], SLQ-
                         48).
Acoustic..............  Mine               Ship crews detect, locate,   1-4 hours...........  HF4..............  Study Area, Apra           4         28
                         Countermeasure     identify, and avoid mines                                             Harbor.
                         Exercise--Surfac   while navigating
                         e Ship Sonar       restricted areas or
                         (SQQ-32, MCM).     channels, such as while
                                            entering or leaving port.
Acoustic..............  Mine               Surface ship crews detect    1-4 hours...........  HF4..............  Study Area, Apra           4         28
                         Countermeasure     and avoid mines while                                                 Harbor.
                         Exercise--Towed    navigating restricted
                         Sonar (AQS-20).    areas or channels using
                                            towed active sonar
                                            systems.
Explosive.............  Mine               Personnel disable threat     Up to 4 hours.......  E5, E6...........  Agat Bay site,            20        140
                         Neutralization--   mines using explosive                                                 Piti, and Outer
                         Explosive          charges.                                                              Apra Harbor.
                         Ordnance
                         Disposal.
Acoustic..............  Submarine Mine     Submarine crews practice     Varies..............  HF1..............  Study Area,                1          7
                         Exercise.          detecting mines in a                                                  Mariana
                                            designated area.                                                      Littorals, Inner/
                                                                                                                  Outer Apra
                                                                                                                  Harbor.
Explosive.............  Underwater         Navy divers conduct various  Varies..............  E5, E6...........  Agat Bay site,            45        315
                         Demolition         levels of training and                                                Piti, and Outer
                         Qualification/     certification in placing                                              Apra Harbor.
                         Certification.     underwater demolition
                                            charges.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Surface Warfare (SUW)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Explosive.............  Bombing Exercise   Fixed-wing aircrews deliver  1 hour..............  E9, E10, E12.....  Study Area,               37        259
                         (Air-to-Surface).  bombs against stationary                                              Special Use
                                            surface targets.                                                      Airspace.
Explosive.............  Gunnery Exercise   Fixed-wing and helicopter    1 hour..............  E1, E2...........  Study Area > 12          120        840
                         (GUNEX) (Air-to-   aircrews fire medium-                                                 NM from land,
                         Surface)--Medium-  caliber guns at surface                                               Special Use
                         caliber.           targets.                                                              Airspace.
Explosive.............  GUNEX (Surface-to- Small boat crews fire        1 hour..............  E2...............  Study Area > 12           20        140
                         Surface) Boat--    medium-caliber guns at                                                NM from land,
                         Medium-caliber.    surface targets.                                                      Special Use
                                                                                                                  Airspace.
Explosive.............  GUNEX (Surface-to- Surface ship crews fire      Up to 3 hours.......  E5...............  Study Area > 12          255      1,785
                         Surface) Ship--    large-caliber guns at                                                 NM from land,
                         Large-caliber.     surface targets.                                                      Special Use
                                                                                                                  Airspace.
Explosive.............  GUNEX (Surface-to- Surface ship crews fire      2-3 hours...........  E1...............  Study Area > 12          234      1,638
                         Surface) Ship--    medium and small-caliber                                              NM from land,
                         Small- and         guns at surface targets.                                              Special Use
                         Medium-caliber.                                                                          Airspace.
Explosive.............  Maritime Security  Helicopter, surface ship,    Up to 3 hours.......  E2...............  Study Area; MIRC.         40        280
                         Operations.        and small boat crews
                                            conduct a suite of
                                            maritime security
                                            operations at sea, to
                                            include visit, board,
                                            search and seizure,
                                            maritime interdiction
                                            operations, force
                                            protection, and anti-
                                            piracy operations.
Explosive.............  Missile Exercise   Fixed-wing and helicopter    2 hours.............  E6, E8, E10......  Study Area > 12           10         70
                         (Air-to-Surface)   aircrews fire air-to-                                                 NM from land,
                         (MISSILEX [A-S]).  surface missiles at                                                   Special Use
                                            surface targets.                                                      Airspace.
Explosive.............  Missile Exercise   Helicopter aircrews fire     1 hour..............  E3...............  Study Area > 12          110        770
                         (Air-to-           both precision-guided and                                             NM from land,
                         Surface)--Rocket   unguided rockets at                                                   Special Use
                         (MISSILEX [A-S]--  surface targets.                                                      Airspace.
                         Rocket).
Explosive.............  Missile Exercise   Surface ship crews defend    2-5 hours...........  E6, E10..........  Study Area > 50           28        196
                         (Surface-to-       against surface threats                                               NM from land,
                         Surface)           (ships or small boats) and                                            Special Use
                         (MISSILEX [S-S]).  engage them with missiles.                                            Airspace.

[[Page 5793]]

 
Explosive.............  Sinking Exercise.  Aircraft, ship, and          4-8 hours, possibly   E5, E8, E10, E11,  Study Area > 50            1          4
                                            submarine crews              over.                 E12, TORP2.        NM from land and
                                            deliberately sink a         1-2 days............                      > 1,000 fathoms
                                            seaborne target, usually a                                            depth.
                                            decommissioned ship made
                                            environmentally safe for
                                            sinking according to U.S.
                                            Environmental Protection
                                            Agency standards, with a
                                            variety of ordnance.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                Other Training Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic..............  Submarine          Submarine crews operate      Up to 2 hours.......  HF1, MF3.........  Study Area, Apra           8         56
                         Navigation.        sonar for navigation and                                              Harbor, and
                                            detection while transiting                                            Mariana
                                            into and out of port                                                  littorals.
                                            during reduced visibility.
Acoustic..............  Submarine Sonar    Maintenance of submarine     Up to 1 hour........  MF3..............  Study Area; Apra          86        602
                         Maintenance.       sonar and other system                                                Harbor and
                                            checks are conducted                                                  Mariana
                                            pierside or at sea.                                                   littorals.
Acoustic..............  Surface Ship       Maintenance of surface ship  Up to 4 hours.......  MF1..............  Study Area; Apra          44        308
                         Sonar              sonar and other system                                                Harbor and
                         Maintenance.       checks are conducted                                                  Mariana
                                            pierside or at sea.                                                   littorals.
Acoustic..............  Unmanned           Units conduct training with  Up to 24 hours......  FLS2, M3, SAS2,    MIRC; Apra Harbor         64        448
                         Underwater         unmanned underwater                                SAS4.              and Mariana
                         Vehicle Training.  vehicles from a variety of                                            littorals.
                                            platforms, including
                                            surface ships, small
                                            boats, and submarines.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Testing Activities--ASW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic; Explosive...  Anti-Submarine     The test evaluates the       8 hours.............  ASW2, ASW5, E1,    Study Area > 3 NM         26        182
                         Warfare Tracking   sensors and systems used                           E3, MF5, MF6.      from land.
                         Test--Maritime     by maritime patrol
                         Patrol Aircraft    aircraft to detect and
                         (Sonobuoys).       track submarines and to
                                            ensure that aircraft
                                            systems used to deploy the
                                            tracking systems perform
                                            to specifications and meet
                                            operational requirements.
Acoustic..............  Anti-Submarine     This event is similar to     2-6 flight hours....  MF5, TORP1.......  Study Area > 3 NM         20        140
                         Warfare Torpedo    the training event torpedo                                            from land.
                         Test.              exercise. Test evaluates
                                            anti-submarine warfare
                                            systems onboard rotary-
                                            wing and fixed-wing
                                            aircraft and the ability
                                            to search for, detect,
                                            classify, localize, track,
                                            and attack a submarine or
                                            similar target.
Acoustic..............  Anti-Submarine     Ships and their supporting   1-2 weeks, with 4-8   ASW1, ASW2, ASW3,  Mariana Island           100        700
                         Warfare Mission    platforms (e.g.,             hours of active       ASW5, MF12, MF4,   Range Complex.
                         Package Testing.   helicopters and unmanned     sonar use with        MF5, TORP1.
                                            aerial systems) detect,      intervals of non-
                                            localize, and prosecute      activity in between.
                                            submarines.
Acoustic..............  At-Sea Sonar       At-sea testing to ensure     From 4 hours to 11    HF1, HF6, M3,      Study Area.......          7         49
                         Testing.           systems are fully            days.                 MF3, MF9.
                                            functional in an open
                                            ocean environment
Acoustic; Explosive...  Torpedo            Air, surface, or submarine   1-2 days during       ASW3, HF1, HF6,    Mariana Island             3          9
                         (Explosive)        crews employ explosive and   daylight hours.       MF1, MF3, MF4,     Range Complex.
                         Testing.           non-explosive torpedoes                            MF5, MF6, TORP1,
                                            against artificial                                 TORP2, E8, E11.
                                            targets.
Acoustic..............  Torpedo (Non-      Air, surface, or submarine   Up to 2 weeks.......  ASW3, ASW4, HF1,   Mariana Island             7         49
                         explosive)         crews employ non-explosive                         HF6, LF4, MF1,     Range Complex.
                         Testing.           torpedoes against                                  MF3, MF4, MF5,
                                            submarines or surface                              MF6, TORP1,
                                            vessels.                                           TORP2, TORP3.
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 5794]]

 
                                                                      Mine Warfare
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic; Explosive...  Mine               Air, surface, and            1-10 days, with       HF4, E4..........  MIRC; nearshore            3         21
                         Countermeasure     subsurface vessels           intermittent use of                      and littorals.
                         and                neutralize threat mines      countermeasure/
                         Neutralization     and mine-like objects.       neutralization
                         Testing.                                        systems during this
                                                                         period.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Vessel Evaluation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic..............  Undersea Warfare   Ships demonstrate            Up to 10 days.......  HF4, MF1, MF4,     MIRC.............          1          7
                         Testing.           capability of                                      MF5, TORP1.
                                            countermeasure systems and
                                            underwater surveillance,
                                            weapons engagement, and
                                            communications systems.
                                            This tests ships' ability
                                            to detect, track, and
                                            engage undersea targets.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Additional activities utilizing sources not listed in the Major Training Event and coordinated exercise bins above may occur during these exercises.
  All acoustic sources which may be used during training and testing activities have been accounted for in the modeling and analysis presented in this
  application and in the 2019 MITT DSEIS/OEIS.

Summary of Acoustic and Explosive Sources Analyzed for Training and 
Testing

    Tables 4 and 5 show the acoustic and explosive source classes, bins 
and quantity used in either hours or counts associated with the Navy's 
proposed training and testing activities over a seven-year period in 
the MITT Study Area that were analyzed in the Navy's rulemaking/LOA 
application. Table 4 describes the acoustic source classes (i.e., low-
frequency (LF), mid-frequency (MF), and high-frequency (HF)) that could 
occur over seven years under the proposed training and testing 
activities. Acoustic source bin use in the proposed activities would 
vary annually. The seven-year totals for the proposed training and 
testing activities take into account that annual variability.

    Table 4--Acoustic Source Classes Analyzed and Number Used for Seven-Year Period for Training and Testing
                                        Activities in the MITT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                                                        7-year
       Source class category                Bin             Description         Unit       Annual       total
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF): Sources that     LF4               LF sources equal to          H             1            7
 produce signals less than 1 kHz.    LF5                180 dB and up to 200        H            10           65
                                                        dB.
                                                       LF sources less than
                                                        180 dB.
Mid-Frequency (MF): Tactical and     MF1               Hull-mounted surface         H         1,818        9,051
 non-tactical sources that produce                      ship sonars (e.g.,
 signals between 1 and 10 kHz.                          AN/SQS-53C and AN/
                                                        SQS-60).
                                     MF1K              Kingfisher mode              H             3           21
                                                        associated with MF1
                                                        sonars.
                                     MF3               Hull-mounted                 H           227        1,589
                                                        submarine sonars
                                                        (e.g., AN/BQQ-10).
                                     MF4               Helicopter-deployed          H           185        1,295
                                                        dipping sonars
                                                        (e.g., AN/AQS-22).
                                     MF5               Active acoustic               C        2,094       14,658
                                                        sonobuoys (e.g.,
                                                        DICASS).
                                     MF6               Active underwater             C           74          518
                                                        sound signal devices
                                                        (e.g., MK 84 SUS).
                                     MF9               Active sources (equal        H            29          203
                                                        to 180 dB and up to
                                                        200 dB) not
                                                        otherwise binned.
                                     MF11              Hull-mounted surface         H           304        2.128
                                                        ship sonars with an
                                                        active duty cycle
                                                        greater than 80%.
+                                    MF12              Towed array surface          H           616        4,312
                                                        ship sonars with an
                                                        active duty cycle
                                                        greater than 80%.
High-Frequency (HF): Tactical and    HF1               Hull-mounted                 H            73          511
 non-tactical sources that produce                      submarine sonars
 signals between 10 and 100 kHz.                        (e.g., AN/BQQ-10).
                                     HF3               Other hull-mounted           H             4           28
                                                        submarine sonars
                                                        (classified).
                                     HF4               Mine detection,              H         1,472       10,304
                                                        classification, and
                                                        neutralization sonar
                                                        (e.g., AN/SQS-20).
                                     HF6               Active sources (equal        H           309        2,163
                                                        to 180 dB and up to
                                                        200 dB) not
                                                        otherwise binned.

[[Page 5795]]

 
Anti-Submarine Warfare (ASW):        ASW1              MF systems operating         H           192        1,344
 Tactical sources (e.g., active      ASW2               above 200 dB.                C          554        3,808
 sonobuoys and acoustic                                MF Multistatic Active
 countermeasures systems) used                          Coherent sonobuoy
 during ASW training and testing                        (e.g., AN/SSQ-125).
 activities.
                                     ASW3              MF towed active              H         3,124       21,868
                                                        acoustic
                                                        countermeasure
                                                        systems (e.g., AN/
                                                        SLQ-25).
                                     ASW4              MF expendable active          C          332        2,324
                                                        acoustic device
                                                        countermeasures
                                                        (e.g., MK 3).
                                     ASW5              MF sonobuoys with            H            50          350
                                                        high duty cycles.
Torpedoes (TORP): Source classes     TORP1             Lightweight torpedo           C           71          485
 associated with the active                             (e.g., MK 46, MK 54,
 acoustic signals produced by                           or Anti[dash]Torpedo
 torpedoes.                                             Torpedo).
                                     TORP2             Heavyweight torpedo           C           62          434
                                                        (e.g., MK 48).
                                     TORP3             Heavyweight torpedo           C            6           42
                                                        test (e.g., MK 48).
Forward Looking Sonar (FLS):         FLS2              HF sources with short        H             4           28
 Forward or upward looking object                       pulse lengths,
 avoidance sonars used for ship                         narrow beam widths,
 navigation and safety.                                 and focused beam
                                                        patterns.
Acoustic Modems (M): Systems used    M3                MF acoustic modems           H            31          217
 to transmit data through the water.                    (greater than 190
                                                        dB).
Synthetic Aperture Sonars (SAS):     SAS2              HF SAS systems.......        H           449        3,143
 Sonars in which active acoustic     SAS4              MF to HF broadband           H             6           42
 signals are post-processed to form                     mine countermeasure
 high-resolution images of the                          sonar.
 seafloor.
----------------------------------------------------------------------------------------------------------------
Notes: H= hours; C = count.

    Table 5 describes the number of in-water explosives that could be 
used in any year under the proposed training and testing activities. 
Under the proposed activities bin use would vary annually, and the 
seven-year totals for the proposed training and testing activities take 
into account that annual variability.

     Table 5--Explosive Source Bins Analyzed and Number Used for Seven-Year Period for Training and Testing
                                      Activities Within the MITT Study Area
----------------------------------------------------------------------------------------------------------------
                      Net explosive        Example         Modeled  detonation
        Bin            weight  (lb)   explosive source        depths  (ft)            Annual       7-year  total
----------------------------------------------------------------------------------------------------------------
E1.................         0.1-0.25  Medium-caliber    0.3, 60.................             768           5,376
                                       projectiles.
E2.................        >0.25-0.5  Anti-swimmer      0.3.....................             400           2,800
                                       grenade.
E3.................         >0.5-2.5  57 mm projectile  0.3, 60.................             683           4,591
E4.................           >2.5-5  Mine              33, 197.................              44             308
                                       neutralization
                                       charge.
E5.................            >5-10  5 in projectiles  0.3, 10, 98.............           1,221           8,547
E6.................           >10-20  15 lb shaped      0.3, 98.................              29             203
                                       charge.
E8.................          >60-100  250 lb bomb;      0.3, 150................             134             932
                                       Light weight
                                       torpedo.
E9.................         >100-250  500 lb bomb.....  0.3.....................             110             770
E10................         >250-500  1,000 lb bomb...  0.3.....................              78             546
E11................         >500-650  Heavy weight      150,300.................               5              17
                                       torpedo.
E12................       >650-1,000  2,000 lb bomb...  0.3.....................              48             336
----------------------------------------------------------------------------------------------------------------
Notes: (1) net explosive weight refers to the equivalent amount of TNT. The actual weight of a munition may be
  larger due to other components. (2) in = inch(es), lb = pound(s), ft = feet.

Vessel Movement

    In the MITT Study Area, there is one port on Guam as well as Naval 
Base Guam. There are three ports within the CNMI including Port of 
Rota, Port of Tinian, and Port of Saipan. However, Navy ships are 
mostly associated with transits into and out of Apra Harbor on Guam. 
U.S. Navy vessels do not berth at other locations in the MITT Study 
Area other than Apra Harbor. Within the CNMI, the Port of Rota (also 
called Rota West Harbor) is located on the southwestern tip of the 
island. It is a very small, poorly sheltered port with a pierside water 
depth of 6 to 10 ft, which limits the size of vessels that can access 
the pier. The Port of Rota is mainly used as a port for ferry boats 
transporting tourists and residents from its sister island, Tinian. The 
Port of Tinian is a well-sheltered small port. Mobile Oil operates a 
fuel plant at the port, and a ferry service transports tourists from 
Saipan to Tinian. The Port of Saipan is the largest of the three CNMI 
ports. The port of Saipan is on the southwest shore and houses 
commercial ships, small local boats or ferries, and military vessels 
(ships that are not managed by the Navy or part of these proposed 
activities). Guam's Jose D. Leon Guerrero Commercial Port is on Cabras 
Island along the southwest portion of Guam. The Port Authority of Guam, 
administers the Commercial Port, Agana Boat Basin, and the Agat Marina.
    While the ships assigned to any particular homeport change 
periodically, Naval Base Guam is not home to any surface fleet 
commands. There are no Navy surface warships

[[Page 5796]]

homeported in Guam. The types of vessels currently homeported in Apra 
Harbor include submarines, support vessels like a submarine tender and 
a military sealift (i.e., logistics) unit, and small vessels like 
coastal riverine craft. Small vessels stay in nearshore, coastal 
waters. Navy large vessel movements for training and testing in the 
MITT Study Area often occur when U.S. West Coast and Hawaii based 
strike groups or independent deployers (i.e., single vessels) transit 
to and from the Western Pacific, Indian Ocean, and Arabian Gulf. The 
Navy also maintains a contingent of vessels homeported in Japan that 
also visit the MITT Study Area to participate in various single unit or 
multi-unit training activities and MTEs. Unlike other Navy range 
complexes associated with fleet concentration areas, there may be long 
periods, from multiple weeks up to a month or more (e.g., 1-3 months), 
without any significant Navy large surface vessel presence in the MITT 
Study Area. These gaps are the result of Navy ships training in other 
range complexes as part of pre-deployment preparations and Japan-based 
ships deployed to other portions of the Western Pacific for operational 
reasons.
    The western approaches to Apra Harbor are the central corridor of 
vessel movements in the MITT Study Area, as visiting, transiting, and 
homeported vessels pull in and out for port calls and resupply. 
Depending on a given exercise, many of the participating ships could 
use Apra Harbor prior to or after the event depending on operational 
schedules. A significant amount of MIW events with vessel movements 
would be more likely west of Guam and adjacent to Apra Harbor, 
depending on the event.
    The majority of the Air Warfare (launches from aircraft carriers 
and surface ships), ASW, Electronic Warfare, Strike Warfare, and SUW 
training and testing events involving vessel movement (Table 6 below) 
occurs in or adjacent to the specified training and testing areas shown 
in Figure 2-2 of the Navy's rulemaking/LOA application. Vessels 
involved in ASW training and testing typically use water depths greater 
than 200 m and areas greater than 3 NM from shore, conducting most 
events in designated areas or other locations well offshore. For safety 
reasons, the Navy also does not conduct explosive events such as vessel 
gunnery exercises less than 12 NM from shore, and more often in 
designated areas further offshore.
    These generalities do not preclude individual ships or strike 
groups from conducting select training and testing between designated 
Navy training and testing areas, nor does it preclude select training 
or testing west of Guam in the eastern and central Philippine Sea or in 
the transit lane between Hawaii and the MITT Study Area. While the vast 
majority of activities are scheduled in designated areas, operational 
schedules could necessitate training or testing in other at-sea 
portions of the MITT Study Area and commanders are always able to 
conduct unit-level or small group training and testing as opportunities 
arise and schedules allow.
    Destroyers and cruisers would be the only surface ships conducting 
Naval Surface Fire Support Exercise (FIREX)--Land-based target (Land) 
and would transit the waters adjacent to FDM, though the duration of 
these single events is relatively short (4-6 hours). The ships, because 
of both ship draft and training requirements, are typically a mile or 
more offshore in deeper waters during execution of FIREX events. 
Because of constricted scheduling needs at FDM for both surface and 
aviation activities, ships conducting FIREX move into the desired 
range, fire off an allotted amount of ordnance (inert or explosive 
five-inch projectiles), and depart back to other areas within the MITT 
Study Area.
    Amphibious Warfare activities have slightly different vessel 
movements than activities in other warfare areas. Amphibious MTEs 
(Joint Expeditionary Exercise, Marine Air Ground Task Force Exercise 
(Amphibious)--Battalion) and other Amphibious Warfare activities 
involve amphibious assault ships maneuvering offshore then approaching 
designated beach landing areas to offload marines in landing craft, 
amphibious assault vehicles, or helicopters. Typical landing locations 
depending on activity type include Guam, FDM, Rota, Saipan, and Tinian 
(Tinian Military Lease Area). For large surface vessels during 
amphibious warfare activities, the objective is to not approach too 
close to shore, which would put a ship at risk from shore-based 
defenses. Typically, amphibious transport ships deploy landing craft, 
amphibious assault vehicles, or helicopters from several miles 
offshore. Given the steep nearshore bathymetry in the Mariana Islands 
greater than 3NM from shore, these ships are still in significantly 
deep water while deploying units (>200 m).
    The only areas with consistently high concentrations of Navy vessel 
movement would be within Apra Harbor Guam and the coastal approaches to 
and from Apra Harbor. Some amphibious events use Tinian as a landing 
area so amphibious ships could occur in the offshore waters off that 
island. Most other activities are spread throughout the greater MITT 
Study Area with a high degree of spatial and temporal separation 
between activities.
    The Navy tabulated annual at-sea vessel steaming days proposed for 
the MITT Study Area. Across all warfare areas and activities, 493 days 
of Navy at-sea time would occur annually in the MITT Study Area (Table 
6). Amphibious Warfare activities account for 48 percent of total 
surface ship days, MTEs account for 38 percent, ASW activities account 
for 8 percent, and Air Warfare, ASW and Other activities (sonar 
maintenance, anchoring) account for 2 percent each (Table 6). In 
comparison to the Hawaii-Southern California Training and Testing 
(HSTT) Study Area, the estimated number of at-sea annual days in the 
MITT Study Area is approximately ten times less than in the HSTT Study 
Area over the same time period.

                        Table 6--Annual Navy Surface Ship Days Within the MITT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                                    Annual days
                   MITT events                      Annual days     Percent by      by warfare      Percent by
                                                                       event           area        warfare area
----------------------------------------------------------------------------------------------------------------
AIR WARFARE.....................................  ..............  ..............               9             1.9
    GUNNEX (Lg).................................               2             0.3  ..............  ..............
    GUNNEX (Sm).................................               3             0.6  ..............  ..............
    MISSILEX....................................               5             0.9  ..............  ..............
AMPHIBIOUS WARFARE..............................  ..............  ..............             299            60.7
    Fire Support (Land Target)..................               5             1.0  ..............  ..............
    Amphibious Rehearsal........................             144            29.2  ..............  ..............
    Amphibious Assault..........................              14             2.8  ..............  ..............

[[Page 5797]]

 
    Amphibious Raid.............................               3             0.6  ..............  ..............
    Marine Air Ground Task Force Exercise.......              40             8.1  ..............  ..............
    Non-Combatant Evacuation Op.................              67            13.5  ..............  ..............
    Humanitarian Assist/Disaster Relief Op......               7             1.4  ..............  ..............
    Special Purpose Marine Air Ground Task Force              20             4.1  ..............  ..............
     Exercise...................................
SURFACE WARFARE.................................  ..............  ..............              41             8.4
    MISSILEX....................................               2             0.4  ..............  ..............
    GUNNEX (Lg).................................              14             2.8  ..............  ..............
    GUNNEX (Med)................................              10             2.0  ..............  ..............
    GUNNEX (Sm).................................               6             1.3  ..............  ..............
    SINKEX......................................               7             1.4  ..............  ..............
    Maritime Security Op........................               3             0.5  ..............  ..............
ANTI-SUBMARINE WARFARE..........................  ..............  ..............               8             1.6
    Tracking Exercise...........................               8             1.5  ..............  ..............
    Torpedo Exercise............................               1             0.1  ..............  ..............
MAJOR TRAINING EXERCISES........................  ..............  ..............             125            24.5
    Joint Expeditionary Exercise................              63            12.9  ..............  ..............
    Joint Multi-Strike Group Exercise...........              62            12.5  ..............  ..............
OTHER...........................................  ..............  ..............              10             2.1
    Surface Ship Sonar Maintenance..............               7            1.5%  ..............  ..............
    Precision Anchoring.........................               3            0.6%  ..............  ..............
                                                 ---------------------------------------------------------------
        Total...................................             493  ..............  ..............  ..............
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------

    Additional details on Navy at-sea vessel movement are provided in 
the 2019 MITT DSEIS/OEIS.

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 military missions and combat operations 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 on 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:
    [ssquf] Ship, submarine, and aircraft safety manuals;
    [ssquf] Ship, submarine, and aircraft standard operating manuals;
    [ssquf] Fleet Area Control and Surveillance Facility range 
operating instructions;
    [ssquf] Fleet exercise publications and instructions;
    [ssquf] Naval Sea Systems Command test range safety and standard 
operating instructions;
    [ssquf] Navy instrumented range operating procedures;
    [ssquf] Naval shipyard sea trial agendas;
    [ssquf] Research, development, test, and evaluation plans;
    [ssquf] Naval gunfire safety instructions;
    [ssquf] Navy planned maintenance system instructions and 
requirements;
    [ssquf] Federal Aviation Administration regulations; and
    [ssquf] 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 proposed 
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 2019 MITT DSEIS/OEIS.

[ssquf] Vessel Safety
[ssquf] Weapons Firing Safety
[ssquf] Target Deployment and Retrieval Safety
[ssquf] Towed In-Water Device Procedures

    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 2.3.3 Standing Operating 
Procedures of the 2019 MITT DSEIS/OEIS for greater detail.

Description of Marine Mammals and Their Habitat in the Area of the 
Specified Activities

    Marine mammal species that have the potential to occur in the MITT 
Study Area are presented in Table 7. The Navy requests authorization to 
take individuals of 26 marine mammal species by Level A and Level B 
harassment incidental to training and testing activities from the use 
of sonar and other transducers, and in-water detonations. The Navy does 
not request authorization for any serious injuries or mortalities of 
marine mammals, and NMFS agrees that serious injury and mortality is 
unlikely to occur from the Navy's activities. There are no areas of 
critical habitat designated under the Endangered Species Act (ESA), 
Biologically Important Areas, National Marine Sanctuaries, or unusual 
mortality events for marine mammals in the MITT Study Area. However, 
there are areas known to be important for humpback whale breeding and 
calving, which are described below.
    Information on the status, distribution, abundance, population 
trends, habitat, and ecology of marine mammals in the MITT Study Area 
may be found in Chapter 4 of the Navy's rulemaking/LOA application. 
NMFS has reviewed this information and found it to be accurate and 
complete. Additional information on the general biology and ecology of 
marine mammals are included in the 2019 MITT DSEIS/OEIS. There are only 
a few species for which

[[Page 5798]]

stock information exists for the MITT Study Area. Table 7 incorporates 
data from the U.S. Pacific and the Alaska Marine Mammal Stock 
Assessments (Carretta et al., 2017c; Muto et al., 2017b); as well as 
incorporates the best available science, including monitoring data from 
the Navy's marine mammal research efforts.

                                              Table 7--Marine Mammal Occurrence Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               Status                                       Occurrence *
           Common  name                Scientific  name   ----------------------------------------------------------------------------------------------
                                                                    MMPA                     ESA              Mariana  Islands       Transit  corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       Mysticetes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale........................  Balaenoptera musculus  D.....................  E.....................  Seasonal..............  Seasonal.
Bryde's whale.....................  Balaenoptera edeni...  ......................  n/a...................  Regular...............  Regular.
Fin whale.........................  Balaenoptera physalus  D.....................  E.....................  Rare..................  Rare.
Humpback whale....................  Megaptera              (\1\).................  E.....................  Seasonal..............  Seasonal.
                                     novaeangliae.
Minke whale.......................  Balaenoptera           ......................  n/a...................  Seasonal..............  Seasonal.
                                     acutorostrata.
Omura's whale.....................  Balaenoptera omurai..  ......................  n/a...................  Rare..................  Rare.
Sei whale.........................  Balaenoptera borealis  D.....................  E.....................  Seasonal..............  Seasonal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       Odontocetes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blainville's beaked whale.........  Mesoplodon             ......................  n/a...................  Regular...............  Regular
                                     densirostris.
Common bottlenose dolphin.........  Tursiops truncatus...  ......................  n/a...................  Regular...............  Regular.
Cuvier's beaked whale.............  Ziphius cavirostris..  ......................  n/a...................  Regular...............  Regular.
Dwarf sperm whale.................  Kogia sima...........  ......................  n/a...................  Regular...............  Regular.
False killer whale................  Pseudorca crassidens.  ......................  n/a...................  Regular...............  Regular.
Fraser's dolphin..................  Lagenodelphis hosei..  ......................  n/a...................  Regular...............  Regular.
Ginkgo-toothed beaked whale.......  Mesoplodon ginkgodens  ......................  n/a...................  Regular...............  Regular.
Killer whale......................  Orcinus orca.........  ......................  n/a...................  Regular...............  Regular.
Longman's beaked whale............  Indopacetus pacificus  ......................  n/a...................  Regular...............  Regular.
Melon-headed whale................  Peponocephala electra  ......................  n/a...................  Regular...............  Regular.
Pantropical spotted dolphin.......  Stenella attenuata...  ......................  n/a...................  Regular...............  Regular.
Pygmy killer whale................  Feresa attenuata.....  ......................  n/a...................  Regular...............  Regular.
Pygmy sperm whale.................  Kogia breviceps......  ......................  n/a...................  Regular...............  Regular.
Risso's dolphin...................  Grampus griseus......  ......................  n/a...................  Regular...............  Regular.
Rough-toothed dolphin.............  Steno bredanensis....  ......................  n/a...................  Regular...............  Regular.
Short-finned pilot whale..........  Globicephala           ......................  n/a...................  Regular...............  Regular.
                                     macrorhynchus.
Sperm whale.......................  Physeter               D.....................  E.....................  Regular...............  Regular.
                                     macrocephalus.
Spinner dolphin...................  Stenella longirostris  ......................  n/a...................  Regular...............  Regular.
Striped dolphin...................  Stenella coeruleoalba  ......................  n/a...................  Regular...............  Regular.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Humpback whales in the Mariana Islands have not been assigned a stock by NMFS in the Alaska or Pacific Stock Assessment Reports given they are not
  recognized in those reports as being present in U.S. territorial waters (Carretta et al., 2017c; Carretta et al., 2018; Muto et al., 2017b; Muto et
  al., 2018), but because individuals from the Western North Pacific Distinct Population Segment have been photographically identified in the MITT Study
  Area, humpback whales in the Mariana Islands are assumed to be part of the Western North Pacific Stock.
Note: Status MMPA, D = depleted; ESA, E = endangered.
* Species occur in both the Mariana Islands and in the Transit Corridor, both of which are included in the overall MITT Study Area. The transit corridor
  is outside the geographic boundaries of the MIRC, but is a route across the high seas for Navy ships transiting between the MIRC and the HRC. Although
  not part of a defined range complex, vessels and aircraft would at times conduct basic and routine unit-level activities such as gunnery and sonar
  training while in transit in the corridor as long as the training would not interfere with the primary objective of reaching their intended
  destination. Ships also conduct sonar maintenance, which includes active sonar transmissions.

Humpback Whale Breeding and Calving Areas

    Humpback whale breeding and calving have been documented in the 
MITT Study Area and particularly in the shallow waters (mostly within 
the 200 m isobath) offshore of Saipan at Marpi Reef and Chalan Kanoa 
Reef. Based on surveys conducted by NMFS' Pacific Islands Fisheries 
Science Center (PIFSC) during the winter months (January to March) 
2015-2019, there were 22 encounters with mother/calf pairs with a total 
of 14 mother/calf pairs and all calves were considered born within the 
current season and one neotate (Hitt et al., in press). Additionally, 
competitive groups were observed in 2017 and 2018 (Hill et al., in 
press). Additional information from surveys and passive acoustic 
hydrophone recordings in the Mariana Islands has confirmed the presence 
of mother-calf pairs, non-calf whales, and singing males in the MITT 
Study Area (Fulling et al., 2011; Hill et al., 2016a; Hill et al., 
2018; Munger et al., 2014; Munger et al., 2015; Norris et al., 2012; 
Oleson and Hill, 2010a; Oleson et al., 2015; U.S. Department of the 
Navy, 2007; Uyeyama et al., 2012). Future surveys are needed to 
determine the full extent of the humpback whale breeding habitat 
through the Mariana Archipelago; however, the available data confirms 
the shallow waters surrounding Marpi and Chalan Kanoa reefs are 
important to breeding and calving humpback whales.

Species Not Included in the Analysis

    Consistent with the analysis provided in the 2015 MITT FEIS/OEIS 
and the previous Phase II rulemaking for the MITT Study Area, the 
species carried forward for analysis and in the Navy's rulemaking/LOA 
application are those likely to be found in the MITT Study Area based 
on the most recent sighting, survey, and habitat modeling data 
available. The analysis does not include species that may have once 
inhabited or transited the area, but have not been sighted in recent 
years (e.g., species that no longer occur in the area due to factors 
such as 19th-century commercial exploitation). These species include 
the North Pacific right whale (Eubalaena japonica), the western 
subpopulation of

[[Page 5799]]

gray whale (Eschrichtius robustus), short-beaked common dolphin 
(Delphinus delphis), Indo-Pacific bottlenose dolphin (Tursiops 
aduncus), northern elephant seal (Mirounga angustirostris), and 
Hawaiian monk seal (Monachus schauinslandi). The reasons for not 
including each of these species is explained below and NMFS agrees 
these species are unlikely to occur in the MITT Study Area. Further 
details can be found in the 2015 MITT FEIS/OEIS.
    The North Pacific right whale population is very small, likely in 
the low hundred (NMFS 2019). Contemporary sightings of North Pacific 
right whales have mostly occurred in the central North Pacific and 
Bering Sea. Sightings have been reported as far south as central Baja 
California in the eastern North Pacific, as far south as Hawaii in the 
central North Pacific, and as far north as the sub-Arctic waters of the 
Bering Sea and the Sea of Okhotsk in the summer. Migration patterns of 
the North Pacific right whale are unknown, although it is thought the 
whales spend the summer in far northern feeding grounds and migrate 
south to warmer waters, such as southern California, during the winter. 
Due to their known homerange it is unlikely that a North Pacific right 
whale would occur in the MITT Study Area. North Pacific right whales 
have not been previously documented in the MITT Study Area. For the 
reasons discussed above, this species is not discussed further.
    For the western subpopulation of gray whales there currently are no 
data available to suggest that gray whales would transit the MITT Study 
Area when migrating from the western to eastern Pacific. There have 
only been 13 records of gray whales in Japanese waters since 1990 
(Nambu et al., 2010). The Okhotsk Sea and Sakhalin Island are located 
far to the north off Russia, and the South China Sea begins 
approximately 1,458 NM east of the MITT Study Area. Given what is known 
of their present range, nearshore affinity, and extralimital occurrence 
in tropical waters, it is highly unlikely that this species would be 
present in the MITT Study Area (Reilly et al., 2000; Weller et al., 
2002; Wiles, 2005; Nambu et al., 2010). In addition, no gray whales 
have been previously documented in the MITT Study Area. For the reasons 
discussed above, this species is not discussed further.
    The short-beaked common dolphin is found worldwide in temperate, 
tropical, and subtropical seas. The range of this species may extend 
entirely across the tropical and temperate north Pacific (Heyning and 
Perrin, 1994); however, this species prefers areas with large seasonal 
changes in surface temperature and thermocline depth (the point between 
warmer surface water and colder water) (Au and Perryman, 1985). They 
are one of the most abundant species found in temperate waters off the 
U.S. West Coast (Barlow and Forney, 2007). In tropical seas, they are 
typically sighted in upwelling-modified waters such as those in the 
eastern tropical Pacific (Au and Perryman, 1985; Ballance and Pitman, 
1998; Reilly, 1990). The absence of known areas of major upwelling in 
the western tropical Pacific suggests that common dolphins are not 
found in the MITT Study Area (Hammond et al., 2008). In addition, no 
short-beaked common dolphins have been previously documented in the 
MITT Study Area. For the reasons discussed above, this species is not 
discussed further.
    The Indo-Pacific bottlenose dolphin generally occurs over shallow 
coastal waters on the continental shelf. Although typically associated 
with continental margins, they do occur around oceanic islands; 
however, the MITT Study Area is not included in their known geographic 
range, and there are no documented sightings there (Hammond et al., 
2008). In addition, no Indo-Pacific bottlenose dolphins have been 
previously documented in the MITT Study Area. For the reasons discussed 
above, this species is not discussed further.
    The likelihood of a Hawaiian monk seal being present in the MITT 
Study Area is extremely low. There are no confirmed records of Hawaiian 
monk seals in the Micronesia region; although, Reeves et al. (1999) and 
Eldredge (1991, 2003) have noted occurrence records for unidentified 
seal species in the Marshall and Gilbert Islands. It is possible that 
Hawaiian monk seals wander from the Hawaiian Islands to appear at the 
Marshall or Gilbert Islands in the Micronesia region (Eldredge, 1991). 
However, the Marshall Islands are located approximately 1,180 mi. 
(1,900 km) from Guam and the Gilbert Islands are located even farther 
to the east. Given the extremely low likelihood of this species 
occurring in the MITT Study Area. No Hawaiian monk seals have been 
previously documented in the MITT Study Area. For the reasons discussed 
above, this species is not discussed further.
    Northern elephant seals (Mirounga angustirostris) are common on 
island and mainland haul-out sites in Baja California, Mexico north 
through central California. Elephant seals spend several months at sea 
feeding and travel as far north as the Gulf of Alaska and forage in the 
mid-Pacific as far south as approximately 40 degrees north latitude. 
Vagrant individuals do sometimes range to the western north Pacific. 
The most far-ranging individual appeared on Nijima Island off the 
Pacific coast of Japan in 1989 (Kiyota et al., 1992). Although northern 
elephant seals may wander great distances, it is very unlikely that 
they would travel to Japan and then continue traveling to the MITT 
Study Area. No Northern elephant seals have been previously documented 
in the MITT Study Area. For the reasons discussed above, this species 
is not discussed further.
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):
    [ssquf] Low-frequency cetaceans (mysticetes): Generalized hearing 
is estimated to occur between approximately 7 Hz and 35 kHz;
    [ssquf] Mid-frequency cetaceans (larger toothed whales, beaked 
whales, and most delphinids): Generalized hearing is

[[Page 5800]]

estimated to occur between approximately 150 Hz and 160 kHz;
    [ssquf] 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;
    [ssquf] Pinnipeds in water; Phocidae (true seals): Generalized 
hearing is estimated to occur between approximately 50 Hz to 86 kHz; 
and
    [ssquf] 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 details concerning these groups and associated frequency 
ranges, please see NMFS (2016) for a review of the available 
information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a 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 rule includes a 
quantitative analysis of the number of instances of take that could 
occur from these activities. The Preliminary Analysis and Negligible 
Impact Determination section considers the content of this section, the 
Estimated Take of Marine Mammals section, and the Proposed Mitigation 
Measures section to draw conclusions regarding the likely impacts of 
these activities on the reproductive success or survivorship of 
individuals and whether those impacts on individuals are likely to 
adversely affect the species through effects on annual rates of 
recruitment or survival.
    The Navy has requested authorization for the take of marine mammals 
that may occur incidental to training and testing activities in the 
MITT Study Area. The Navy analyzed potential impacts to marine mammals 
from acoustic and explosive sources in its rulemaking/LOA application. 
NMFS carefully reviewed the information provided by the Navy along with 
independently reviewing applicable scientific research and literature 
and other information to evaluate the potential effects of the Navy's 
activities on marine mammals, which are presented in this section.
    Other potential impacts to marine mammals from training and testing 
activities in the MITT Study Area were analyzed in the 2019 MITT DSEIS/
OEIS, in consultation with NMFS as a cooperating agency, and determined 
to be unlikely to result in marine mammal take. These include 
incidental take from vessel strike and serious injury or mortality from 
explosives. Therefore, the Navy has not requested authorization for 
take of marine mammals incidental to other components of their proposed 
Specified Activities, and we agree that incidental take is 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 transducers) and 
impulsive (explosives) stressors.
    For the purpose of MMPA incidental take authorizations, NMFS' 
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) and non-auditory injury), serious 
injury, or mortality, including 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 the species or stocks and their habitat (i.e., mitigation 
measures); (2) to determine whether the specified activities would have 
a negligible impact on the affected species or stocks of marine mammals 
(based on whether it is likely that the activities would adversely 
affect the species or stocks 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 stocks for subsistence uses (however, there are no 
subsistence communities that would be affected in the MITT Study Area, 
so this determination is inapplicable to this rulemaking); and (4) to 
prescribe requirements pertaining to monitoring and reporting.
    In this section, NMFS provides a description of the ways marine 
mammals may be generally 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, 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. The Preliminary 
Analysis and Negligible Impact Determination section assesses whether 
the proposed authorized take would have a negligible impact on the 
affected species.

Potential Effects of Underwater Sound

    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, Southall et al., 2019a). 
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. 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. We 
first describe general 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

[[Page 5801]]

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
    Non-impulsive sources of sound can cause direct physiological 
effects including noise-induced loss of hearing sensitivity (or 
``threshold shift''), nitrogen decompression, acoustically-induced 
bubble growth, and injury due to sound-induced acoustic resonance. Only 
noise-induced hearing loss is anticipated to occur due to the Navy's 
activities. Acoustically-induced (or 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 subsection.
Hearing Loss--Threshold Shift
    Marine mammals exposed to high-intensity sound, or to lower-
intensity sound for prolonged periods, can experience hearing threshold 
shift, which is the loss of hearing sensitivity at certain frequency 
ranges after cessation of sound (Finneran, 2015). Threshold shift can 
be permanent (PTS), in which case the loss of hearing sensitivity is 
not fully recoverable, or temporary (TTS), in which case the animal's 
hearing threshold would recover over time (Southall et al., 2007). 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 of varying amounts (e.g., an animal's hearing sensitivity might 
be reduced by only 6 dB or reduced by 30 dB). While there is no simple 
functional relationship between TTS and PTS or other auditory injury 
(e.g., neural degeneration), as TTS increases, the likelihood that 
additional exposure sound pressure level (SPL) or duration will result 
in PTS or other injury also increases (see also the 2019 MITT DSEIS/
OEIS for additional discussion). Exposure thresholds for the occurrence 
of PTS or other auditory injury can therefore be defined based on a 
specific amount of TTS; that is, although an exposure has been shown to 
produce only TTS, we assume that any additional exposure may result in 
some PTS or other injury. The specific upper limit of TTS is based on 
experimental data showing amounts of TTS that have not resulted in PTS 
or injury. In other words, we do not need to know the exact functional 
relationship between TTS and PTS or other injury, we only need to know 
the upper limit for TTS before some PTS or injury is possible. 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 threshold shift: 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 
threshold shift and the frequency range in which it occurs. Generally, 
the amount of threshold shift, 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 sound exposure 
level (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 threshold shift 
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

[[Page 5802]]

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).
    The NMFS 2016 Acoustic Technical Guidance (revised in 2018) (NMFS 
2016, 2018), which was used in the assessment of effects for this rule, 
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. More recently, Southall et al. (2019a) evaluated 
Southall et al. (2007) and used updated scientific information to 
propose revised noise exposure criteria to predict onset of auditory 
effects in marine mammals (i.e., PTS and TTS onset). Southall et al. 
(2019a) note that the quantitative processes described and the 
resulting exposure criteria (i.e., thresholds and auditory weighting 
functions) are largely identical to those in Finneran (2016) and NMFS 
(2016 and 2018). They only differ in that the Southall et al. (2019a) 
exposure criteria are more broadly applicable as they include all 
marine mammal species (rather than only those under NMFS jurisdiction) 
for all noise exposures (both in air and underwater for amphibious 
species) and, while the hearing group compositions are identical, they 
renamed the hearing groups.
    Many studies have examined noise-induced hearing loss in marine 
mammals (see Finneran (2015) and Southall et al. (2019a) for 
summaries), however for cetaceans, published data on the onset of TTS 
are limited to the captive bottlenose dolphin, beluga, harbor porpoise, 
and Yangtze finless porpoise, and for pinnipeds in water, measurements 
of TTS are limited to harbor seals, elephant seals, and California sea 
lions. These studies examine hearing thresholds measured in marine 
mammals before and after exposure to intense sounds. The difference 
between the pre-exposure and post-exposure thresholds can then be used 
to determine the amount of threshold shift at various post-exposure 
times. NMFS has reviewed the available studies, which are summarized 
below (see also the 2019 MITT DSEIS/OEIS which includes additional 
discussion on TTS studies related to sonar and other transducers):
     The method used to test hearing may affect the resulting 
amount of measured TTS, with neurophysiological measures producing 
larger amounts of TTS compared to psychophysical measures (Finneran et 
al., 2007; Finneran, 2015).
     The amount of TTS varies with the hearing test frequency. 
As the exposure SPL increases, the frequency at which the maximum TTS 
occurs also increases (Kastelein et al., 2014b). For high-level 
exposures, the maximum TTS typically occurs one-half to one octave 
above the exposure frequency (Finneran et al., 2007; Mooney et al., 
2009a; Nachtigall et al., 2004; Popov et al., 2011; Popov et al., 2013; 
Schlundt et al., 2000). The overall spread of TTS from tonal exposures 
can therefore extend over a large frequency range (i.e., narrowband 
exposures can produce broadband (greater than one octave) TTS).
     The amount of TTS increases with exposure SPL and duration 
and is correlated with SEL, especially if the range of exposure 
durations is relatively small (Kastak et al., 2007; Kastelein et al., 
2014b; Popov et al., 2014). As the exposure duration increases, 
however, the relationship between TTS and SEL begins to break down. 
Specifically, duration has a more significant effect on TTS than would 
be predicted on the basis of SEL alone (Finneran et al., 2010a; Kastak 
et al., 2005; Mooney et al., 2009a). This means if two exposures have 
the same SEL but different durations, the exposure with the longer 
duration (thus lower SPL) will tend to produce more TTS than the 
exposure with the higher SPL and shorter duration. In most acoustic 
impact assessments, the scenarios of interest involve shorter duration 
exposures than the marine mammal experimental data from which impact 
thresholds are derived; therefore, use of SEL tends to over-estimate 
the amount of TTS. Despite this, SEL continues to be used in many 
situations because it is relatively simple, more accurate than SPL 
alone, and lends itself easily to scenarios involving multiple 
exposures with different SPL.
     The amount of TTS depends on the exposure frequency. 
Sounds at low frequencies, well below the region of best sensitivity, 
are less hazardous than those at higher frequencies, near the region of 
best sensitivity (Finneran and Schlundt, 2013). The onset of TTS--
defined as the exposure level necessary to produce 6 dB of TTS (i.e., 
clearly above the typical variation in threshold measurements)--also 
varies with exposure frequency. At low frequencies, onset-TTS exposure 
levels are higher compared to those in the region of best sensitivity.
     TTS can accumulate across multiple exposures, but the 
resulting TTS will be less than the TTS from a single, continuous 
exposure with the same SEL (Finneran et al., 2010a; Kastelein et al., 
2014b; Kastelein et al., 2015b; Mooney et al., 2009b). This means that 
TTS predictions based on the total, cumulative SEL will overestimate 
the amount of TTS from intermittent exposures such as sonars and 
impulsive sources.
     The amount of observed TTS tends to decrease with 
increasing time following the exposure; however, the relationship is 
not monotonic (i.e., increasing exposure does not always increase TTS). 
The time required for complete recovery of hearing depends on the 
magnitude of the initial shift; for relatively small shifts recovery 
may be complete in a few minutes, while large shifts (e.g., 
approximately 40 dB) may require several days for recovery. Under many 
circumstances TTS recovers linearly with the logarithm of time 
(Finneran et al., 2010a, 2010b; Finneran and Schlundt, 2013; Kastelein 
et al., 2012a; Kastelein et al., 2012b; Kastelein et al., 2013a; 
Kastelein et al., 2014b; Kastelein et al., 2014c; Popov et al., 2011; 
Popov et al., 2013; Popov et al., 2014). This means that for each 
doubling of recovery time, the amount of TTS will decrease by the same 
amount (e.g., 6 dB recovery per doubling of time).
    Nachtigall et al. (2018) and Finneran (2018) describe the 
measurements of hearing sensitivity of multiple odontocete species 
(bottlenose dolphin, harbor porpoise, beluga, and false killer whale) 
when a relatively loud sound was preceded by a warning sound. These 
captive animals were shown to reduce hearing sensitivity when warned of 
an impending intense sound. Based on these experimental observations of 
captive animals, the authors suggest that wild animals may dampen their 
hearing during prolonged exposures or if conditioned to anticipate 
intense sounds. Finneran recommends further investigation of the 
mechanisms of hearing sensitivity reduction in order to understand the 
implications for interpretation of existing TTS data obtained from 
captive animals, notably for considering TTS due to short duration, 
unpredictable exposures.
    Marine mammal hearing plays a critical role in communication with 
conspecifics and in interpretation of

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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 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 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-Induced Bubble Formation Due to Sonars and Other Pressure-
Related Impacts
    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).
    As described in additional detail in the Nitrogen Decompression 
subsection of the 2019 MITT DSEIS/OEIS, marine mammals generally are 
thought to deal with nitrogen loads in their blood and other tissues, 
caused by gas exchange from the lungs under conditions of high ambient 
pressure during diving, through anatomical, behavioral, and 
physiological adaptations (Hooker et al., 2012). Although not a direct 
injury, variations in marine mammal diving behavior or avoidance 
responses have been hypothesized to result in nitrogen off-gassing in 
super-saturated tissues, possibly to the point of deleterious

[[Page 5804]]

vascular and tissue bubble formation (Hooker et al., 2012; Jepson et 
al., 2003; Saunders et al., 2008) with resulting symptoms similar to 
decompression sickness, however the process is still not well 
understood.
    In 2009, Hooker et al. tested two mathematical models to predict 
blood and tissue tension N2 (PN2) using field data from 
three beaked whale species: northern bottlenose whales, Cuvier's beaked 
whales, and Blainville's beaked whales. The researchers aimed to 
determine if physiology (body mass, diving lung volume, and dive 
response) or dive behavior (dive depth and duration, changes in ascent 
rate, and diel behavior) would lead to differences in PN2 
levels and thereby decompression sickness risk between species. In 
their study, they compared results for previously published time depth 
recorder data (Hooker and Baird, 1999; Baird et al., 2006, 2008) from 
Cuvier's beaked whale, Blainville's beaked whale, and northern 
bottlenose whale. They reported that diving lung volume and extent of 
the dive response had a large effect on end-dive PN2. Also, 
results showed that dive profiles had a larger influence on end-dive 
PN2 than body mass differences between species. Despite diel 
changes (i.e., variation that occurs regularly every day or most days) 
in dive behavior, PN2 levels showed no consistent trend. 
Model output suggested that all three species live with tissue 
PN2 levels that would cause a significant proportion of 
decompression sickness cases in terrestrial mammals. The authors 
concluded that the dive behavior of Cuvier's beaked whale was different 
from both Blainville's beaked whale, and northern bottlenose whale, and 
resulted in higher predicted tissue and blood N2 levels (Hooker et al., 
2009). They also suggested that the prevalence of Cuvier's beaked 
whales stranding after naval sonar exercises could be explained by 
either a higher abundance of this species in the affected areas or by 
possible species differences in behavior and/or physiology related to 
MF active sonar (Hooker et al., 2009).
    Bernaldo de Quiros et al. (2012) showed that, among stranded 
whales, deep diving species of whales had higher abundances of gas 
bubbles compared to shallow diving species. Kvadsheim et al. (2012) 
estimated blood and tissue PN2 levels in species 
representing shallow, intermediate, and deep diving cetaceans following 
behavioral responses to sonar and their comparisons found that deep 
diving species had higher end-dive blood and tissue N2 
levels, indicating a higher risk of developing gas bubble emboli 
compared with shallow diving species. Fahlmann et al. (2014) evaluated 
dive data recorded from sperm, killer, long-finned pilot, Blainville's 
beaked and Cuvier's beaked whales before and during exposure to low-
frequency (1-2 kHz), as defined by the authors, and mid-frequency (2-7 
kHz) active sonar in an attempt to determine if either differences in 
dive behavior or physiological responses to sonar are plausible risk 
factors for bubble formation. The authors suggested that CO2 
may initiate bubble formation and growth, while elevated levels of 
N2 may be important for continued bubble growth. The authors 
also suggest that if CO2 plays an important role in bubble 
formation, a cetacean escaping a sound source may experience increased 
metabolic rate, CO2 production, and alteration in cardiac 
output, which could increase risk of gas bubble emboli. However, as 
discussed in Kvadsheim et al. (2012), the actual observed behavioral 
responses to sonar from the species in their study (sperm, killer, 
long-finned pilot, Blainville's beaked, and Cuvier's beaked whales) did 
not imply any significantly increased risk of decompression sickness 
due to high levels of N2. Therefore, further information is 
needed to understand the relationship between exposure to stimuli, 
behavioral response (discussed in more detail below), elevated 
N2 levels, and gas bubble emboli in marine mammals. The 
hypotheses for gas bubble formation related to beaked whale strandings 
is that beaked whales potentially have strong avoidance responses to MF 
active sonars because they sound similar to their main predator, the 
killer whale (Cox et al., 2006; Southall et al., 2007; Zimmer and 
Tyack, 2007; Baird et al., 2008; Hooker et al., 2009). Further 
investigation is needed to assess the potential validity of these 
hypotheses.
    To summarize, while there are several hypotheses, there is little 
data directly connecting intense, anthropogenic underwater sounds with 
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.
Injury Due to Sonar-Induced Acoustic Resonance
    An object exposed to its resonant frequency will tend to amplify 
its vibration at that frequency, a phenomenon called acoustic 
resonance. Acoustic resonance has been proposed as a potential 
mechanism by which a sonar or sources with similar operating 
characteristics could damage tissues of marine mammals. In 2002, NMFS 
convened a panel of government and private scientists to investigate 
the potential for acoustic resonance to occur in marine mammals 
(National Oceanic and Atmospheric Administration, 2002). They modeled 
and evaluated the likelihood that Navy mid-frequency sonar (2-10 kHz) 
caused resonance effects in beaked whales that eventually led to their 
stranding. The workshop participants concluded that resonance in air-
filled structures was not likely to have played a primary role in the 
Bahamas stranding in 2000. They listed several reasons supporting this 
finding including (among others): Tissue displacements at resonance are 
estimated to be too small to cause tissue damage; tissue-lined air 
spaces most susceptible to resonance are too large in marine mammals to 
have resonant frequencies in the ranges used by mid-frequency or low-
frequency sonar; lung resonant frequencies increase with depth, and 
tissue displacements decrease with depth so if resonance is more likely 
to be caused at depth it is also less likely to have an affect there; 
and lung tissue damage has not been observed in any mass, multi-species 
stranding of beaked whales. The frequency at which resonance was 
predicted to occur in the animals' lungs was 50 Hz, well below the 
frequencies used by the mid-frequency sonar systems associated with the 
Bahamas event. The workshop participants focused on the March 2000 
stranding of beaked whales in the Bahamas as high-quality data were 
available, but the workshop report notes that the results apply to 
other sonar-related stranding events. For the reasons given by the 2002 
workshop participants, we do not anticipate injury due to sonar-induced 
acoustic resonance from the Navy's proposed activities.
Physiological Stress
    There is growing interest in monitoring and assessing the impacts 
of stress responses to sound in marine animals. Classic stress 
responses begin when an animal's central nervous

[[Page 5805]]

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 
serious fitness consequences. However, when an animal does not have 
sufficient energy reserves to satisfy the energetic costs of a stress 
response, energy resources must be diverted from other biotic 
functions, 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 of distress will last until 
the animal replenishes its energetic reserves sufficiently 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 are well-studied through 
controlled experiments in both laboratory and free-ranging 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). However, it should be noted (and as is 
described in additional detail in the 2019 MITT DSEIS/OEIS) that our 
understanding of the functions of various stress hormones (for example, 
cortisol), is based largely upon observations of the stress response in 
terrestrial mammals. Atkinson et al., 2015 note that the endocrine 
response of marine mammals to stress may not be the same as that of 
terrestrial mammals because of the selective pressures marine mammals 
faced during their evolution in an ocean environment. For example, due 
to the necessity of breath-holding while diving and foraging at depth, 
the physiological role of epinephrine and norepinephrine (the 
catecholamines) in marine mammals might be different than in other 
mammals.
    As described in the 2019 MITT DSEIS/OEIS, marine mammals naturally 
experience stressors within their environment and as part of their life 
histories. Changing weather and ocean conditions, exposure to disease 
and naturally occurring toxins, lack of prey availability, and 
interactions with predators all contribute to the stress a marine 
mammal experiences (Atkinson et al., 2015). Breeding cycles, periods of 
fasting, and social interactions with members of the same species are 
also stressors, although they are natural components of an animal's 
life history. Anthropogenic activities have the potential to provide 
additional stressors beyond those that occur naturally (Fair et al., 
2014; Meissner et al., 2015; Rolland et al., 2012). Anthropogenic 
stressors potentially include such things as fishery interactions, 
pollution, tourism, and ocean noise.
    Acoustically induced stress in marine mammals is not well 
understood. There are ongoing efforts to improve our understanding of 
how stressors impact marine mammal populations (see Navy funded 
examples here: e.g., King et al., 2015; New et al., 2013a; New et al., 
2013b; Pirotta et al., 2015a), however little data exist on the 
consequences of sound-induced stress response (acute or chronic). 
Factors potentially affecting a marine mammal's response to a stressor 
include the individual's life history stage, sex, age, reproductive 
status, overall physiological and behavioral plasticity, and whether 
they are na[iuml]ve or experienced with the sound (e.g., prior 
experience with a stressor may result in a reduced response due to 
habituation (Finneran and Branstetter, 2013; St. Aubin and Dierauf, 
2001a)). Stress responses due to exposure to anthropogenic sounds or 
other stressors and their effects on marine mammals have been reviewed 
(Fair and Becker, 2000; Romano et al., 2002b) and, more rarely, studied 
in wild populations (e.g., Romano et al., 2002a). For example, Rolland 
et al. (2012) found that noise reduction from reduced ship traffic in 
the Bay of Fundy was associated with decreased stress in North Atlantic 
right whales. These and other studies lead to a reasonable expectation 
that some marine mammals will experience physiological stress responses 
upon exposure to acoustic stressors and that it is possible that some 
of these would be classified as ``distress.'' In addition, any animal 
experiencing TTS would likely also experience stress responses (NRC, 
2003).
    Other research has also investigated the impact from vessels (both 
whale-watching and general vessel traffic noise), and demonstrated 
impacts do occur (Bain, 2002; Erbe, 2002; Lusseau, 2006; Williams et 
al., 2006; Williams et al., 2009; Noren et al., 2009; Read et al., 
2014; Rolland et al., 2012; Skarke et al., 2014; Williams et al., 2013; 
Williams et al., 2014a; Williams et al., 2014b; Pirotta et al., 2015). 
This body of research has

[[Page 5806]]

generally investigated impacts associated with the presence of chronic 
stressors, which differ significantly from the proposed Navy training 
and testing vessel activities in the MITT 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) 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. 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 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.
    Most sound-induced stress response studies in marine mammals have 
focused on acute responses to sound either by measuring catecholamines 
or by measuring heart rate as an assumed proxy for an acute stress 
response. As described in the 2019 MITT DSEIS/OEIS, belugas 
demonstrated no catecholamine response to the playback of oil drilling 
sounds (Thomas et al., 1990) but showed a small but statistically 
significant increase in catecholamines following exposure to impulsive 
sounds produced from a seismic water gun (Romano et al., 2004). A 
bottlenose dolphin exposed to the same seismic water gun signals did 
not demonstrate a catecholamine response, but did demonstrate a 
statistically significant elevation in aldosterone (Romano et al., 
2004), albeit the increase was within the normal daily variation 
observed in this species (St. Aubin et al., 1996). Increases in heart 
rate were observed in bottlenose dolphins to which known calls of other 
dolphins were played, although no increase in heart rate was observed 
when background tank noise was played back (Miksis et al., 2001). 
Unfortunately, in this study, it cannot be determined whether the 
increase in heart rate was due to stress or an anticipation of being 
reunited with the dolphin to which the vocalization belonged. 
Similarly, a young beluga's heart rate was observed to increase during 
exposure to noise, with increases dependent upon the frequency band of 
noise and duration of exposure, and with a sharp decrease to normal or 
below normal levels upon cessation of the exposure (Lyamin et al., 
2011). Spectral analysis of heart rate variability corroborated direct 
measures of heart rate (Bakhchina et al., 2017). This response might 
have been in part due to the conditions during testing, the young age 
of the animal, and the novelty of the exposure; a year later the 
exposure was repeated at a slightly higher received level and there was 
no heart rate response, indicating the beluga whale may have acclimated 
to the noise exposure. Kvadsheim et al. (2010) measured the heart rate 
of captive hooded seals during exposure to sonar signals and found an 
increase in the heart rate of the seals during exposure periods versus 
control periods when the animals were at the surface. When the animals 
dove, the normal dive-related bradycardia (decrease in heart rate) was 
not impacted by the sonar exposure. Similarly, Thompson et al. (1998) 
observed a rapid but short-lived decrease in heart rates in harbor and 
grey seals exposed to seismic air guns (cited in Gordon et al., 2003). 
Williams et al. (2017) recently monitored the heart rates of narwhals 
released from capture and found that a profound dive bradycardia 
persisted, even though exercise effort increased dramatically as part 
of their escape response following release. Thus, although some limited 
evidence suggests that tachycardia might occur as part of the acute 
stress response of animals that are at the surface, the dive 
bradycardia persists during diving and might be enhanced in response to 
an acute stressor.
    Despite the limited amount of data available on sound-induced 
stress responses for marine mammals exposed to anthropogenic sounds, 
studies of other marine animals and terrestrial animals would also lead 
us to expect that some marine mammals experience physiological stress 
responses and, perhaps, physiological responses that would be 
classified as ``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. However, take due to aircraft noise 
is not anticipated as a result of the Navy's activities. 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.
Auditory 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, or 
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. 
As described in detail in the 2019 MITT DSEIS/OEIS, 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

[[Page 5807]]

of individual animals, groups of animals, or entire populations. 
Masking can lead to behavioral changes including vocal changes (e.g., 
Lombard effect, increasing amplitude, or changing frequency), cessation 
of foraging, and leaving an area, to both signalers and receivers, in 
an attempt to compensate for noise levels (Erbe et al., 2016). 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 only occurs during the sound exposure. Because masking 
(without resulting in threshold shift) is not associated with abnormal 
physiological function, it is not considered a physiological effect, 
but rather a potential behavioral effect.
    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 (including critical 
ratios, or the lowest signal-to-noise ratio in which animals can detect 
a signal, Finneran and Branstetter, 2013; Johnson et al., 1989; 
Southall et al., 2000) 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 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).
    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.
    Impacts on signal detection, measured by masked detection 
thresholds, are not the only important factors to address when 
considering the potential effects of masking. As marine mammals use 
sound to recognize conspecifics, prey, predators, or other biologically 
significant sources (Branstetter et al., 2016), it is also important to 
understand the impacts of masked recognition thresholds (often called 
``informational masking''). Branstetter et al., 2016 measured masked 
recognition thresholds for whistle-like sounds of bottlenose dolphins 
and observed that they are approximately 4 dB above detection 
thresholds (energetic masking) for the same signals. Reduced ability to 
recognize a conspecific call or the acoustic signature of a predator 
could have severe negative impacts. Branstetter et al., 2016 observed 
that if ``quality communication'' is set at 90 percent recognition the 
output of communication space models (which are based on 50 percent 
detection) would likely result in a significant decrease in 
communication range.
    As marine mammals use sound to recognize predators (Allen et al., 
2014; Cummings and Thompson, 1971; Cur[eacute] et al., 2015; Fish and 
Vania, 1971), the presence of masking noise may also prevent marine 
mammals from responding to acoustic cues produced by their predators, 
particularly if it occurs in the same frequency band. For example, 
harbor seals that reside in the coastal waters off British Columbia are 
frequently targeted by mammal-eating killer whales. The seals 
acoustically discriminate between the calls of mammal-eating and fish-
eating killer whales (Deecke et al., 2002), a capability that should 
increase survivorship while reducing the energy required to attend to 
all killer whale calls. Similarly, sperm whales (Cur[eacute] et al., 
2016; Isojunno et al., 2016), long-finned pilot whales (Visser et al., 
2016), and humpback whales (Cur[eacute] et al., 2015) changed their 
behavior in response to killer whale vocalization playbacks; these 
findings indicate that some recognition of predator cues could be 
missed if the killer whale vocalizations were masked. The potential 
effects of masked predator acoustic cues depends on the duration of the 
masking noise and the likelihood of a marine mammal encountering a 
predator during the time that detection and recognition of predator 
cues are impeded.
    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.
    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 from pre-industrial 
periods, with most

[[Page 5808]]

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.

Impaired Communication

    In addition to making it more difficult for animals to perceive and 
recognize 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'' (or communication 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 (repetition rate), or ceasing to 
vocalize.
    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 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).
    Marine mammals are also known to make vocal changes in response to 
anthropogenic noise. In cetaceans, vocalization changes have been 
reported from exposure to anthropogenic noise sources such as sonar, 
vessel noise, and seismic surveying (see the following for examples: 
Gordon et al., 2003; Di Iorio and Clark, 2010; Hatch et al., 2012; Holt 
et al., 2008; Holt et al., 2011; Lesage et al., 1999; McDonald et al., 
2009; Parks et al., 2007, Risch et al., 2012, Rolland et al., 2012), as 
well as changes in the natural acoustic environment (Dunlop et al., 
2014). Vocal changes can be temporary, or can be persistent. For 
example, model simulation suggests that the increase in starting 
frequency for the North Atlantic right whale upcall over the last 50 
years resulted in increased detection ranges between right whales. The 
frequency shift, coupled with an increase in call intensity by 20 dB, 
led to a call detectability range of less than 3 km to over 9 km 
(Tennessen and Parks, 2016). Holt et al. (2008) 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). 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 surveys 
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.
    In some cases, these vocal changes may have fitness consequences, 
such as an increase in metabolic rates and oxygen consumption, as 
observed in bottlenose dolphins when increasing their call amplitude 
(Holt et al., 2015). A switch from vocal communication to physical, 
surface-generated sounds such as pectoral fin slapping or breaching was 
observed for humpback whales in the presence of increasing natural 
background noise levels, indicating that adaptations to masking may 
also move beyond vocal modifications (Dunlop et al., 2010).
    While these changes all represent possible tactics by the sound-
producing animal to reduce the impact of masking, the receiving animal 
can also reduce masking by using active listening strategies such as 
orienting to the sound source, moving to a quieter location, or 
reducing self-noise from hydrodynamic flow by remaining still. The 
temporal structure of noise (e.g., amplitude modulation) may also 
provide a considerable release from masking through comodulation 
masking release (a reduction of masking that occurs when broadband 
noise, with a frequency spectrum wider than an animal's auditory filter 
bandwidth at the frequency of interest, is amplitude modulated) 
(Branstetter and Finneran, 2008; Branstetter et al., 2013). Signal type 
(e.g., whistles, burst-pulse, sonar clicks) and spectral 
characteristics (e.g., frequency modulated with harmonics) may further 
influence masked detection thresholds (Branstetter et al., 2016; 
Cunningham et al., 2014).
Masking Due to Sonar and Other Transducers
    The functional hearing ranges of mysticetes, odontocetes, and 
pinnipeds underwater 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. Masking by low-frequency 
or mid-frequency active sonar (LFAS and MFAS) with relatively low-duty 
cycles is not anticipated (or would be of very short duration) for most 
cetaceans as sonar signals occur over a relatively short duration and 
narrow bandwidth (overlapping with only a small portion of the hearing 
range). LFAS could overlap in frequency with mysticete vocalizations, 
however LFAS and MFAS does not overlap with vocalizations for most 
marine mammal species. For example, in the presence of LFAS, humpback 
whales were observed to increase the length of their songs (Fristrup et 
al., 2003; Miller et al., 2000), potentially due to the overlap in 
frequencies between the whale song and the LFAS. While dolphin whistles 
and MFAS are similar in frequency, masking is not anticipated (or would 
be of very short duration) due to the low-duty cycle of most sonars.
    As described in the 2019 MITT DSEIS/OEIS, newer high-duty cycle or 
continuous active sonars have more potential to mask vocalizations. 
These sonars transmit more frequently (greater than 80 percent duty 
cycle) than

[[Page 5809]]

traditional sonars, but at a substantially lower source level. HFAS, 
such as pingers that operate at higher repetition rates (e.g., 2-10 kHz 
with harmonics up to 19 kHz, 76 to 77 pings per minute) (Culik et al., 
2001), also operate at lower source levels and have a faster 
attenuation rates due to the higher frequencies used. These lower 
source levels limit the range of impacts, however compared to 
traditional sonar systems, individuals close to the source are likely 
to experience masking at longer time scales. The frequency range at 
which high-duty cycle systems operate overlaps the vocalization 
frequency of many mid-frequency cetaceans. Continuous noise at the same 
frequency of communicative vocalizations may cause disruptions to 
communication, social interactions, acoustically mediated cooperative 
behaviors, and important environmental cues. There is also the 
potential for the mid-frequency sonar signals to mask important 
environmental cues (e.g., predator or conspecific acoustic cues), 
possibly affecting survivorship for targeted animals. While there are 
currently no available studies of the impacts of high-duty cycle sonars 
on marine mammals, masking due to these systems is likely analogous to 
masking produced by other continuous sources (e.g., vessel noise and 
low-frequency cetaceans), and would likely have similar short-term 
consequences, though longer in duration due to the duration of the 
masking noise. These may include changes to vocalization amplitude and 
frequency (Brumm and Slabbekoorn, 2005; Hotchkin and Parks, 2013) and 
behavioral impacts such as avoidance of the area and interruptions to 
foraging or other essential behaviors (Gordon et al., 2003). Long-term 
consequences could include changes to vocal behavior and vocalization 
structure (Foote et al., 2004; Parks et al., 2007), abandonment of 
habitat if masking occurs frequently enough to significantly impair 
communication (Brumm and Slabbekoorn, 2005), a potential decrease in 
survivorship if predator vocalizations are masked (Brumm and 
Slabbekoorn, 2005), and a potential decrease in recruitment if masking 
interferes with reproductive activities or mother-calf communication 
(Gordon et al., 2003).
Masking Due to Vessel Noise
    Masking is more likely to occur in the presence of broadband, 
relatively continuous noise sources such as vessels. Several studies 
have shown decreases in marine mammal communication space and changes 
in behavior as a result of the presence of vessel noise. For example, 
right whales were 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) as well as increasing the 
amplitude (intensity) of their calls (Parks, 2009; Parks et al., 2011). 
Clark et al. (2009) also observed that right whales communication space 
decreased by up to 84 percent in the presence of vessels (Clark et al., 
2009). Cholewiak et al. (2018) also observed loss in communication 
space in Stellwagen National Marine Sanctuary for North Atlantic right 
whales, fin whales, and humpback whales with increased ambient noise 
and shipping noise. Although humpback whales off Australia did not 
change the frequency or duration of their vocalizations in the presence 
of ship noise, their source levels were lower than expected based on 
source level changes to wind noise, potentially indicating some signal 
masking (Dunlop, 2016). Multiple delphinid species have also been shown 
to increase the minimum or maximum frequencies of their whistles in the 
presence of anthropogenic noise and reduced communication space (for 
examples see: Holt et al., 2008; Holt et al., 2011; Gervaise et al., 
2012; Williams et al., 2013; Hermannsen et al., 2014; Papale et al., 
2015; Liu et al., 2017).

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 
predisposed 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), the 
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 received levels (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 received levels 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 received levels (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. Forney et al. (2017) also point out 
that an apparent lack of response (e.g., no displacement or avoidance 
of a sound source) may not necessarily mean

[[Page 5810]]

there is no cost to the individual or population, as some resources or 
habitats may be of such high value that animals may choose to stay, 
even when experiencing stress or hearing loss. Forney et al. (2017) 
recommend considering both the costs of remaining in an area of noise 
exposure such as TTS, PTS, or masking, which could lead to an increased 
risk of predation or other threats or a decreased capability to forage, 
and the costs of displacement, including potential increased risk of 
vessel strike, increased risks of predation or competition for 
resources, or decreased habitat suitable for foraging, resting, or 
socializing. 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 method for predicting Level B harassment in this rule 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 
responses: 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; Gomez et al., 2016) 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. Gomez 
et al. (2016) conducted a review of the literature considering the 
contextual information of exposure in addition to received level and 
found that higher received levels were not always associated with more 
severe behavioral responses and vice versa. 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 predictable 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 subsections 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. 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.
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. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996). The result of a flight response could range from 
brief, temporary exertion and displacement from the area where the 
signal provokes flight to, in extreme cases, 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 species on land. 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 (e.g., Frankel 
and Clark, 2000; Ng and Leung, 2003; Nowacek et al.; 2004; Goldbogen et 
al., 2013a, 2013b). Variations in dive behavior may reflect 
interruptions in biologically significant activities (e.g., foraging) 
or they may be of little biological significance. 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.

[[Page 5811]]

    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, which showed 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 received levels 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. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al.; 2004; Madsen et al., 2006a; Yazvenko et al., 
2007). A determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    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 less likely to produce low 
frequency calls usually associated with feeding behavior (Melc[oacute]n 
et al., 2012). However, Melco[acute]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 (Melco[acute]n et al., 2012). 
Results from the 2010-2011 field season of a 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, 
Southall et al., 2019b). 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. Surface feeding blue 
whales did not show a change in behavior in response to mid-frequency 
simulated and real sonar sources with received levels between 90 and 
179 dB re 1 [micro]Pa, but deep feeding and non-feeding whales showed 
temporary reactions including cessation of feeding, reduced initiation 
of deep foraging dives, generalized avoidance responses, and changes to 
dive behavior (DeRuiter et al., 2017; Goldbogen et al., 2013b; Sivle et 
al., 2015). Goldbogen et al. (2013b) 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.

[[Page 5812]]

    Similarly, while the rates of foraging lunges decrease in humpback 
whales due to sonar exposure, there was variability in the response 
across individuals, with one animal ceasing to forage completely and 
another animal starting to forage during the exposure (Sivle et al., 
2016). In addition, almost half of the animals that avoided were 
foraging before the exposure but the others were not; the animals that 
avoided while not feeding responded at a slightly lower received level 
and greater distance than those that were feeding (Wensveen et al., 
2017). These findings indicate that the behavioral state of the animal 
plays a role in the type and severity of a behavioral response. In 
fact, when the prey field was mapped and used as a covariate in similar 
models looking for a response in the same blue whales, the response in 
deep-feeding behavior by blue whales was even more apparent, 
reinforcing the need for contextual variables to be included when 
assessing behavioral responses (Friedlaender et al., 2016).
Breathing
    Respiration naturally varies 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., 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--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 Auditory 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 in vocalization behavior may result in response to 
anthropogenic noise can occur for any of these modes and may result 
from a need to compete with an increase in background noise or may 
reflect an increased vigilance or a startle response. For example, in 
the presence of potentially masking signals (low-frequency active 
sonar), humpback whales have been observed to increase the length of 
their songs (Miller et al., 2000; Fristrup et al., 2003). 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 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 hours 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 that 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

[[Page 5813]]

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 cumulative sound exposure level (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 
changes in vocalization and/or behavioral responses.
Avoidance
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors. 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. 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). Longer-term 
displacement is possible, however, which may lead to changes in 
abundance or distribution patterns of the affected species in the 
affected region if habituation to the presence of the sound does not 
occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann et 
al., 2006). 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).
    Forney et al. (2017) detailed the potential effects of noise on 
marine mammal populations with high site fidelity, including 
displacement and auditory masking, noting that a lack of observed 
response does not imply absence of fitness costs and that apparent 
tolerance of disturbance may have population-level impacts that are 
less obvious and difficult to document. Avoidance of overlap between 
disturbing noise and areas and/or times of particular importance for 
sensitive species may be critical to avoiding population-level impacts 
because (particularly for animals with high site fidelity) there may be 
a strong motivation to remain in the area despite negative impacts. 
Forney et al. (2017) stated that, for these animals, remaining in a 
disturbed area may reflect a lack of alternatives rather than a lack of 
effects. The authors discuss several case studies, including western 
Pacific gray whales, which are a small population of mysticetes 
believed to be adversely affected by oil and gas development off 
Sakhalin Island, Russia (Weller et al., 2002; Reeves et al., 2005). 
Western gray whales display a high degree of interannual site fidelity 
to the area for foraging purposes, and observations in the area during 
air gun surveys has shown the potential for harm caused by displacement 
from such an important area (Weller et al., 2006; Johnson et al., 
2007). Forney et al. (2017) also discuss beaked whales, noting that 
anthropogenic effects in areas where they are resident could cause 
severe biological consequences, in part because displacement may 
adversely affect foraging rates, reproduction, or health, while an 
overriding instinct to remain could lead to more severe acute effects.
    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 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 received levels 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 5814]]

    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 (referenced 
and summarized in the following paragraphs).
    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 5815]]

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 
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 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 controlled exposure 
experiments on blue whales (n = 19) and of these, 11 controlled 
exposure experiments involved exposure to the MF active sonar sound 
type. For the majority of controlled exposure experiment 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 controlled 
exposure experiment 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 NM) 
from the first controlled exposure experiment 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 controlled exposure 
experiments involving blue whales engaged in surface feeding or social 
behaviors, but was observed in three of the ten controlled exposure 
experiments 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

[[Page 5816]]

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 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 demonstrate clear, strong, 
and pronounced but varied behavioral changes including avoidance with 
associated energetic swimming and cessation of individual foraging 
dives 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. Similar responses by beaked 
whales to sonar have been documented by Stimpert et al., 2014, Falcone 
et al., 2017, DiMarzio et al., 2018, and Joyce et al., 2019. However, 
there are a number of variables influencing response or non-response 
include source distance (close vs. far), received sound levels, and 
other contextual variables such as other sound sources (e.g., vessels, 
etc.) (Manzano-Roth et al., 2016, Falcone et al., 2017, Harris et al., 
2018). Wensveen et al. (2019) found northern bottlenose whales to avoid 
sonar out to distances of 28 km, but these distances are well in line 
with those observed on Navy ranges (Manzano-Roth et al., 2016; Joyce et 
al., 2019) where the animals return once the sonar has ceased. 
Furthermore, beaked whales have also shown response to other non-sonar 
anthropogenic sounds such as commercial shipping and echosounders (Soto 
et al., 2006, Pirotta et al., 2012, Cholewiak et al., 2017). Pirotta et 
al. (2012) documented broadband ship noise causing a significant change 
in beaked whale behavior up to at least 5.2 kilometers away from the 
vessel. Even though beaked whales appear to be sensitive to 
anthropogenic sounds, the level of response at the population level 
does not appear to be significant based on over a decade of research at 
two heavily used Navy training areas in the Pacific (Falcone et al., 
2012, Schorr et al., 2014, DiMarzio et al., 2018, Schorr et al., 2019). 
With the exception of seasonal patterns, DiMarzio et al. (2018) did not 
detect any changes in annual Cuvier's beaked whale abundance estimates 
in Southern California derived from passive acoustic echolocation 
detections over nine years (2010-2018). Similar results for 
Blainville's beaked whales abundance estimates over several years was 
documented in Hawaii (Henderson et al., 2016;, DiMarzio et al., 2018). 
Visually, there have been documented repeated sightings in southern 
California of the same individual Cuvier's beaked whales over 10 years, 
sightings of mother-calf pairs, and recently sightings of the same 
mothers with their second calf (Falcone et al., 2012; Schorr et al., 
2014; Schorr et al., 2019; Schorr, unpublished data).
    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 et al. (1996) 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.
    The strongest baleen whale response in any behavioral response 
study was observed in a minke whale in the 3S2 study, which responded 
at 146 dB re 1 [micro]Pa by strongly avoiding the sound source 
(Kvadsheim et al., 2017; Sivle et al., 2015). Although the minke whale 
increased its swim speed, directional movement, and respiration rate, 
none of these were greater than rates observed in baseline behavior, 
and its dive behavior remained similar to baseline dives. A minke whale 
tagged in the Southern California behavioral response study also 
responded by increasing its directional movement, but maintained its 
speed and dive patterns, and so did not demonstrate as strong of a 
response (Kvadsheim et al., 2017). In addition, the 3S2 minke whale 
demonstrated some of the same avoidance behavior during the controlled 
ship approach with no sonar, indicating at least some of the response 
was to the vessel (Kvadsheim et al., 2017). Martin et al. (2015) found 
that the density of calling minke whales was reduced during periods of 
Navy training involving sonar relative to the periods before training, 
and increased again in the days after training was completed. The 
responses of individual whales could not be assessed, so in this case 
it is unknown whether the decrease in calling animals indicated that 
the animals left the range, or simply ceased calling. Similarly, minke 
whale detections made using Marine Acoustic Recording Instruments off 
Jacksonville, FL, were reduced or ceased altogether during periods of 
sonar use (Simeone et al., 2015; U.S. Department of the Navy, 2013b), 
especially with an increased ping rate (Charif et al., 2015).
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

[[Page 5817]]

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 had 
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.
    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

[[Page 5818]]

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 or resting. These effects have generally not been demonstrated 
for marine mammals, but studies involving fish and terrestrial animals 
have shown that increased vigilance may substantially reduce feeding 
rates (Saino, 1994; Beauchamp and Livoreil, 1997; Fritz et al., 2002; 
Purser and Radford, 2011). 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., 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).
    Chronic disturbance can cause population declines through reduction 
of fitness (e.g., decline in body condition) and subsequent reduction 
in reproductive success, survival, or both (e.g., Harrington and 
Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). 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). However, 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.
    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). 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

[[Page 5819]]

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 a 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 at-sea exercises last for multiple days does not 
necessarily mean that individual animals will be either exposed to 
those activity-related stressors (i.e., sonar) for multiple days or 
further, exposed in a manner that would result in sustained multi-day 
substantive behavioral responses. Stone (2015a) reported data from at-
sea observations during 1,196 airgun surveys from 1994 to 2010. When 
large arrays of airguns (considered to be 500 in\3\ or more) were 
firing, lateral displacement, more localized avoidance, or other 
changes in behavior were evident for most odontocetes. However, 
significant responses to large arrays were found only for the minke 
whale and fin whale. Behavioral responses observed included changes in 
swimming or surfacing behavior, with indications that cetaceans 
remained near the water surface at these times. Cetaceans were recorded 
as feeding less often when large arrays were active. Behavioral 
observations of gray whales during an air gun survey monitored whale 
movements and respirations pre-, during-, and post-seismic survey 
(Gailey et al., 2016). Behavioral state and water depth were the best 
`natural' predictors of whale movements and respiration and, after 
considering natural variation, none of the response variables were 
significantly associated with survey or vessel sounds.
    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 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, the authors chose 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 (see 
MMPA section 410(3)). This definition is useful for considering 
stranding events even when they occur beyond lands and waters under the 
jurisdiction of the United States.
    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 2017).
    Numerous studies suggest that the physiology, behavior, habitat, 
social relationships, age, or condition of cetaceans may cause them to 
strand or might predispose them to strand when

[[Page 5820]]

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.
    In the United States between 2001 and 2009, there were 
approximately 9,895 cetacean strandings and 24,225 pinniped strandings 
(34,120 total). From 2006-2017 there were 19,430 cetacean strandings 
and 55,833 pinniped stranding (75,263 total) (P. Onens, NMFS, pers 
comm. 2019). 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 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 Measures 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 the 
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

[[Page 5821]]

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 U.S. Navy 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 
stranded marine mammals 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 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-hour 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

[[Page 5822]]

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 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 NM (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

[[Page 5823]]

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 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 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,

[[Page 5824]]

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 Moj[aacute]car (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 
Moj[aacute]car 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 NM (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 2001 NMFS/Navy joint 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; 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

[[Page 5825]]

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 Cuvier's beaked whale), 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-Induced Bubble Formation Due 
to Sonars and Other Pressure-related Injury section and an indirect 
cause of stranding). 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 in the MITT Study Area
    Although records of marine mammal strandings exist as far back as 
1878 in Guam, reporting of marine mammal strandings across the Mariana 
Islands has likely only become consistent in recent years. A variety of 
marine mammals have historically stranded in the MITT Study Area and 
have been documented by sources such as the Department of Lands and 
Natural Resources Division of Fish and Wildlife and by the Department 
of Agriculture, Division of Aquatic and Wildlife Resources. Species 
that have stranded include pygmy and dwarf sperm whales, false killer 
whales, melon-headed whales, striped dolphins, sperm whales, and beaked 
whales.
    The stranding of a pygmy sperm whale in 1997 (Trianni and Tenorio, 
2012) is the only other confirmed occurrence of this species in the 
MITT Study Area. There have been four known dwarf sperm whale 
strandings in the Mariana Islands (Trianni and Tenorio, 2012; Uyeyama, 
2014). Three false killer whale strandings occurred in 2000, 2003, and 
2007 (Trianni and Tenorio, 2012; Uyeyama, 2014). There was a live 
stranding of a melon-headed whale on the beach at Inarajan Bay, Guam in 
1980 (Donaldson, 1983; Kami, 1982), and four individuals at Orote in 
2009 (Uyeyama, 2014). Two striped dolphins stranding have occurred, one 
recorded in July1985 (Eldredge, 1991, 2003) and a second in 1993 off 
Saipan (Trianni and Tenorio, 2012). Six sperm whale stranding have 
occurred between 1962 to 2018. Through January 2019, nine beaked whales 
stranding events were reported in the Mariana Islands (Guam and 
Saipan), with the first recorded stranding in 2007. All identified 
beaked whales were Cuvier's beaked whales. Stranding events consisted 
of 1-3 animals. A tenth event, and most recent stranding (live) event 
of a Cuvier's beaked whale, occurred in November 2019 on Rota 
(Commonwealth of the Northern Mariana Islands). A review of Navy 
records indicates that sonar use occurred within 72 hours or 80 NM of 
three of these stranding events (2011, 2015, and 2016) (C. Johnson, 
Navy, pers. comm. 2019).

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

[[Page 5826]]

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 occurs and, if so, whether it results in 
injury, serious injury, or mortality (Knowlton and Kraus, 2001; Laist 
et al., 2001; Jensen and Silber, 2003; Pace and Silber, 2005; 
Vanderlaan and Taggart, 2007; Conn and Silber 2013). 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 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 Large Whale Ship 
Strike Database represents a minimum number of collisions, because the 
vast majority probably goes undetected or unreported. In contrast, Navy 
personnel 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.
    In the MITT Study Area, NMFS has no documented vessel strikes of 
marine mammals by the Navy. This, however, precludes the use of the 
quantitative approach to assess the likelihood of vessel strikes used 
in the 2018 and 2019 incidental take rulemakings for Navy activities in 
the AFTT and HSTT Study Areas, which starts with the number of Navy 
strikes that have occurred in the study area in question. Based on this 
lack of strikes and other factors described below, which the Navy 
presented and NMFS agrees are appropriate factors to consider in 
assessing the likelihood of ship strike, the Navy does not anticipate 
vessel strikes and has not requested authorization to take marine 
mammals by serious injury or mortality within the MITT Study Area 
during training and testing activities. NMFS agrees with the Navy's 
decision based on the analysis and other factors described below. Table 
8 summarizes the factors considered in determining the risk of vessel 
strikes on large whales in the MITT Study Area, along with the 
associated qualitative scores for each, which are described below. For 
species with definite seasonal occurrence (e.g., winter), the approach 
assigns a value of +1 for a ``yes'' and +0.5 for a ``no'' answer to 
account for the possibility that a species could be there. In the other 
columns, the approach assigns a value of +1 for a ``yes'' and -1 for a 
``no'' answer. Justification for inclusion of a vessel strike request 
was based on whether a final evaluation score was greater than zero 
(similar to the analysis in the HSTT rule). None of the final 
evaluation scores for large whales were greater than zero. Regardless 
of the scoring system the Navy presented, NMFS concurs that the factors 
considered are appropriate and that they support a determination that 
vessel strike is not likely to occur.

                  Table 8--Weight of Evidence Approach for Determining the Risk of Vessel Strike on Large Whales in the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                          Justification
                                     Year-round           High Density                                                                   for  including
            Species              presence?  (yes =1/  (>0.001/km\2\)? (yes    Stranding record?    Ship strike record?       Final       vessel  strike
                                      no = 0.5)            =1/no = -1)        (yes = 1/no = -1)     (yes =1/no = -1)      evaluation     request (final
                                                                                                                                         evaluation >0)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale....................  no (0.5)............  no (-1).............  no (-1).............  no (-1).............            -2.5  Did not request
                                                                                                                                         vessel strike.
Fin whale.....................  no (0.5)............  no (-1).............  no (-1).............  no (-1).............            -2.5  Did not request
                                                                                                                                         vessel strike.
Humpback whale................  no (0.5)............  no (-1).............  no (-1).............  no (-1).............            -2.5  Did not request
                                                                                                                                         vessel strike.
Sei whale.....................  no (0.5)............  no (-1).............  no (-1).............  no (-1).............            -2.5  Did not request
                                                                                                                                         vessel strike.

[[Page 5827]]

 
Sperm whale...................  yes (1).............  no (-1).............  yes (1) *...........  no (-1).............               0  Did not request
                                                                                                                                         vessel strike.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Six sperm whale strandings 1962 to 2018.

    Additionally, the Navy has fewer vessel transits than commercial 
entities and other Federal agencies in the MITT Study Area. For 
example, over the five-year period between 2014 and 2018, there were a 
total of 8,984 civilian commercial and Federal agency vessel transits 
(excluding Navy) through Apra Harbor (Table 9). This represents 86 
percent of all vessel transits. The remaining 14 percent were Navy 
vessel transits (total of 1,497 transits). Other Federal agency vessels 
include NOAA research vessels, U.S. Coast Guard vessels, and Department 
of Defense (other than Navy) vessels account for approximately 5 
percent of these total transits. The most frequent ship types arriving 
at the Jose D. Leon Guerrero Commercial Port were container ships (27 
percent), long-line fishing vessels (22 percent), tankers (12 percent), 
and break bulk ships (10 percent) (Port of Guam, unpublished data). 
These statistics do not account for civilian recreational boats, tour 
boats, or personal watercraft (i.e., jet skis). The Navy transits are 
about five times less than commercial shipping transits alone. Overall, 
the percentage of Navy vessel traffic relative to the commercial and 
other Federal agency shipping traffic is much smaller (14 percent), and 
therefore represents a correspondingly smaller threat of potential ship 
strikes when compared to other vessel use.

                  Table 9--Commercial and Navy Ship Transits Through Apra Harbor Guam 2014-2018
----------------------------------------------------------------------------------------------------------------
                                             Commercial and  other
                  Year                      federal  agency vessel         U.S. Navy  vessel       Total  annual
                                                   transits                    transits              transits
----------------------------------------------------------------------------------------------------------------
2014....................................  1,735.....................  339.......................           2,074
2015....................................  1,654.....................  328.......................           1,982
2016....................................  1,534.....................  293.......................           1,827
2017....................................  2,068.....................  264.......................           2,332
2018....................................  1,993.....................  273.......................           2,266
                                         -----------------------------------------------------------------------
    5-yr Total..........................  8,984 (86 percent)........  1,497 (14 percent)........          10,481
        5-yr Average....................  1,797 (86 percent)........  299 (14 percent)..........           2,096
----------------------------------------------------------------------------------------------------------------

    Outside of the vessel traffic as described above, major commercial 
shipping vessels use shipping lanes for transporting goods between 
Hawaii, the continental United States, and Asia. Typically, these are 
great circle routes based on the most direct path between major 
commercial ports. There are no standard commercial routes between Guam 
and the United States. There are also commercial shipping routes from 
Asia and Japan to the equatorial Pacific and Australia that pass 
through larger portions of the Guam and CNMI Economic Exclusive Zones 
(EEZ) as well as the MITT Study Area. Across all warfare areas and 
activities, 493 days of Navy at-sea time would occur annually in MITT, 
three times less than in the HSTT Study Area.
    In addition, 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.
    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 LOA 
requirements. In 2009, the Navy implemented Marine Species Awareness 
Training designed to improve effectiveness of visual observation for 
marine resources, including marine mammals. 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.
    Based on all of these considerations, NMFS has preliminarily 
determined that the Navy's decision not to request take authorization 
for vessel strike of large whales is supported by multiple factors, 
including the lack of ship strike reports in regional NMFS stranding 
records (1962-2018) for the Mariana Islands (including no strikes by 
Navy vessels in the MITT Study Area), the relatively low density of 
large marine mammals in the Mariana Islands, and the seasonal nature of 
several species (blue whales, humpback whales, fin whales, and sei 
whales). In addition, there are relatively small numbers of

[[Page 5828]]

Navy vessels across a large expanse of offshore waters in the MITT 
Study Area, and the procedural mitigation measures that would be in 
place further minimize potential vessel strike.
    In addition to the reasons listed above that make it unlikely that 
the Navy will hit a large whale (more maneuverable ships, larger crew, 
etc.), the following are additional reasons that vessel strike of 
dolphins and small whales is very unlikely. Dating back more than 20 
years and for as long as it has kept records, the Navy has no records 
of individuals of these groups being struck by a vessel as a result of 
Navy activities and, further, their smaller size and maneuverability 
make a strike unlikely. Also, NMFS has never received any reports from 
other authorized activities indicating that these species have been 
struck by vessels. Worldwide ship strike records show little evidence 
of strikes of these groups from the shipping sector and larger vessels, 
and the majority of the Navy's activities involving faster-moving 
vessels (that could be considered more likely to hit a marine mammal) 
are located in offshore areas where smaller delphinid densities are 
lower. Based on this information, NMFS concurs with the Navy's 
assessment that vessel strike is not likely to occur for either large 
whales or smaller marine mammals.
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 potential effects was considered in the 2019 
MITT DSEIS/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 2019 MITT DSEIS/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 a 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 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. 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 (Halvorsen et al., 2012; J[oslash]rgensen et al., 
2005; Juanes et al., 2017; Kane et al., 2010; Kvadsheim & Sevaldsen, 
2005; Popper et al., 2007; Popper and Hawkins, 2016; Watwood et al., 
2016).
    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)

[[Page 5829]]

reported no behavioral responses to mid-frequency naval sonar by 
Atlantic herring; specifically, no escape reactions (vertically or 
horizontally) were 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.
    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).
    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).
    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 or 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. 
Mortality 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 MITT 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 were much lower 
than typical Navy sources within the MITT 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

[[Page 5830]]

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.
    Explosions could kill or injure nearby marine invertebrates. 
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 populations. Long-term consequences 
to marine invertebrate populations would not be expected as a result of 
exposure to sounds or vessels in the MITT Study Area.
    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 MITT 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 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 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 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 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

[[Page 5831]]

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 MITT 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 or 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 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 MITT 
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 MITT 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 2019 MITT DSEIS/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 2019 MITT DSEIS/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 MITT 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 and 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 are based on the maximum amount of take that NMFS 
anticipates is reasonably expected to occur. NMFS coordinated closely 
with the Navy in the development of their incidental take application, 
and 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 are based on the best 
available science and appropriate for authorization.

[[Page 5832]]

    Takes would be in the form of harassment only. For military 
readiness activities, 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).
    Proposed authorized takes would primarily be in the form of Level B 
harassment, as use of the acoustic and explosive sources (i.e., sonar 
and explosives) is more likely to result in behavioral disruption 
(rising to the level of a take as described above) or temporary 
threshold shift (TTS) for marine mammals than other forms of take. 
There is also the potential for Level A harassment, however, in the 
form of auditory injury and/or tissue damage (the latter from 
explosives only) to result from exposure to the sound sources utilized 
in training and testing activities.
    Generally speaking, for acoustic impacts NMFS estimates the amount 
and type of harassment by considering: (1) Acoustic thresholds above 
which NMFS believes the best available science indicates marine mammals 
will be taken by Level B harassment (in this case, as defined in the 
military readiness definition of Level B harassment 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 or event; (3) the density or occurrence of marine mammals within 
these ensonified areas; and (4) the number of days of activities or 
events.

Acoustic Thresholds

    Using the best available science, NMFS, in coordination with the 
Navy, has established acoustic thresholds that identify the most 
appropriate received level of underwater sound above which marine 
mammals exposed to these sound sources could be reasonably expected to 
experience a disruption in behavior 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 non-auditory injury from exposure to 
pressure waves from explosive detonation.
    Despite the quickly evolving science, there are still challenges in 
quantifying expected behavioral responses that qualify as take by Level 
B harassment, especially where the goal is to use one or two 
predictable indicators (e.g., received level and distance) to predict 
responses that are also driven by additional factors that cannot be 
easily incorporated into the thresholds (e.g., context). So, while the 
behavioral Level B harassment thresholds have been refined here to 
better consider the best available science (e.g., incorporating both 
received level and distance), they also still have some built-in 
conservative factors to address the challenge noted. For example, while 
duration of observed responses in the data are now considered in the 
thresholds, some of the responses that are informing take thresholds 
are of a very short duration, such that it is possible some of these 
responses might not always rise to the level of disrupting behavior 
patterns to a point where they are abandoned or significantly altered. 
We describe the application of this Level B harassment threshold as 
identifying the maximum number of instances in which marine mammals 
could be reasonably expected to experience a disruption in behavior 
patterns to a point where they are abandoned or significantly altered. 
In summary, we believe these behavioral Level B harassment thresholds 
are the most appropriate method for predicting behavioral Level B 
harassment given the best available science and the associated 
uncertainty.

Hearing Impairment (TTS/PTS and Tissues Damage and Mortality)

Non-Impulsive and Impulsive
    NMFS' Acoustic Technical Guidance (NMFS, 2018) identifies dual 
criteria to assess auditory injury (Level A harassment) to five 
different marine mammal groups (based on hearing sensitivity) as a 
result of exposure to noise from two different types of sources 
(impulsive or non-impulsive). The Acoustic Technical Guidance also 
identifies criteria to predict TTS, which is not considered injury and 
falls into the Level B harassment category. The Navy's planned activity 
includes the use of non-impulsive (sonar) and impulsive (explosives) 
sources.
    These thresholds (Tables 10 and 11) were developed by compiling and 
synthesizing the best available science and soliciting input multiple 
times from both the public and peer reviewers. The references, 
analysis, and methodology used in the development of the thresholds are 
described in Acoustic Technical Guidance, which may be accessed at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

 Table 10--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             SEL
                                            (weighted)      (weighted)
------------------------------------------------------------------------
Low-Frequency Cetaceans.................             179             199
Mid-Frequency Cetaceans.................             178             198
High-Frequency Cetaceans................             153             173
Phocid Pinnipeds (Underwater)...........             181             201
Otarid 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 11 
to predict the onset of TTS, PTS, tissue damage, and mortality for 
explosives (impulsive) and other impulsive sound sources.

[[Page 5833]]



           Table 11--Onset of TTS, PTS, Tissue Damage, and Mortality Thresholds for Marine Mammals for Explosives and Other Impulsive Sources
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                         Mean onset
    Functional hearing group            Species             Onset TTS            Onset PTS        Mean onset slight      slight lung       Mean onset
                                                                                                   GI tract injury         injury           mortality
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low-frequency cetaceans.........  All mysticetes.....  168 dB SEL           183 dB SEL           237 dB Peak SPL....  Equation 1......  Equation 2.
                                                        (weighted) or 213    (weighted) or 219
                                                        dB Peak SPL.         dB Peak SPL.
Mid-frequency cetaceans.........  Most delphinids,     170 dB SEL           185 dB SEL           237 dB Peak SPL....
                                   medium and large     (weighted) or 224    (weighted) or 230
                                   toothed whales.      dB Peak SPL.         dB Peak SPL.
High-frequency cetaceans........  Porpoises and Kogia  140 dB SEL           155 dB SEL           237 dB Peak SPL....
                                   spp..                (weighted) or 196    (weighted) or 202
                                                        dB Peak SPL.         dB Peak SPL.
Phocidae........................  Harbor seal,         170 dB SEL           185 dB SEL           237 dB Peak SPL....
                                   Hawaiian monk        (weighted) or 212    (weighted) or 218
                                   seal, Northern       dB Peak SPL.         dB Peak SPL.
                                   elephant seal.
Otariidae.......................  California sea       188 dB SEL           203 dB SEL           237 dB Peak SPL....
                                   lion, Guadalupe      (weighted) or 226    (weighted) or 232
                                   fur seal, Northern   dB Peak SPL.         dB Peak SPL.
                                   fur seal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Equation 1: 47.5M 1/3 (1+[DRm/10.1]) 1/6 Pa-sec. Equation 2: 103M 1/3 (1+[D>Rm/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.

    The criteria used to assess the onset of TTS and PTS due to 
exposure to sonars (non-impulsive, see Table 10 above) are discussed 
further in the Navy's rulemaking/LOA application (see Hearing Loss from 
Sonar and Other Transducers in Chapter 6, Section 6.4.2.1, Methods for 
Analyzing Impacts from Sonars and Other Transducers). 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 under the Potential Effects of 
Specified Activities on Marine Mammals and Their Habitat section--
Acoustically Mediated Bubble Growth and other Pressure-related Injury 
and is therefore not considered further in this analysis.
Behavioral Harassment
    Though significantly driven by received level, the onset of Level B 
harassment by 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 (Ellison et al., 2011; Southall et al., 2007). Based on what 
the available science indicates and the practical need to use 
thresholds based on a factor, or factors, that are both predictable and 
measurable for most activities, NMFS uses generalized acoustic 
thresholds based primarily on received level (and distance in some 
cases) to estimate the onset of Level B behavioral harassment.
Sonar
    As noted above, the Navy coordinated with NMFS to develop, and 
propose for use in this rule, Level B behavioral harassment thresholds 
specific to their military readiness activities utilizing active sonar. 
These behavioral response thresholds are used to estimate the number of 
animals that may exhibit a behavioral response that rises to the level 
of a take when exposed 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 Level 
B harassment 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 has carefully reviewed the Navy's Level B behavioral 
thresholds and establishment of cutoff distances for the species, and 
agrees that it is the best available science and is the appropriate 
method to use at this time for determining impacts to marine mammals 
from sonar and other transducers and for calculating take and to 
support the determinations made in this proposed rule.
    As discussed above, marine mammal responses to sound (some of which 
are considered disturbances that rise to the level of a take) are 
highly variable and context specific, i.e., they are 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. This means that 
there is support for considering alternative approaches for estimating 
Level B behavioral harassment. Although the statutory definition of 
Level B harassment for military readiness activities means that a 
natural behavior pattern of a marine mammal is significantly altered or 
abandoned, the current state of science for determining those 
thresholds is somewhat unsettled.
    In its analysis of impacts associated with sonar acoustic sources 
(which was coordinated with NMFS), the Navy used an updated 
conservative approach that likely overestimates the number of takes by 
Level B harassment due to behavioral disturbance and response. Many of 
the behavioral responses identified using the Navy's quantitative 
analysis are most likely to be of moderate severity as described in the 
Southall et al. (2007) behavioral response severity scale. These 
``moderate'' severity responses were considered significant if they 
were sustained for the duration of the exposure or longer. Within the 
Navy's quantitative analysis, many reactions are predicted from 
exposure to sound that may exceed an animal's Level B behavioral 
harassment threshold for only a single exposure (a few seconds) to 
several minutes, and it is likely that some of the resulting estimated 
behavioral responses that are counted as Level B harassment would not 
constitute ``significantly altering or abandoning natural behavioral 
patterns.'' The Navy and NMFS have used the best available science to 
address the challenging differentiation between significant and non-
significant behavioral reactions (i.e., whether the behavior has been 
abandoned or significantly altered such that it qualifies as 
harassment), but have erred on the cautious side where uncertainty

[[Page 5834]]

exists (e.g., counting these lower duration reactions as take), which 
likely results in some degree of overestimation of Level B behavioral 
harassment. We consider application of this Level B behavioral 
harassment threshold, therefore, as identifying the maximum number of 
instances in which marine mammals could be reasonably expected to 
experience a disruption in behavior patterns to a point where they are 
abandoned or significantly altered (i.e., Level B harassment). Because 
this is the most appropriate method for estimating Level B harassment 
given the best available science and uncertainty on the topic, it is 
these numbers of Level B harassment by behavioral disturbance that are 
analyzed in the Preliminary Analysis and Negligible Impact 
Determination section and would be authorized.
    In the Navy's acoustic impact analyses during Phase II (previous 
phase of Navy testing and training, 2013-2018, see also Navy's Criteria 
and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis 
Technical Report, 2012), the likelihood of Level B behavioral 
harassment in response 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 (at the level of a Level B harassment) to the received SPL. 
The BRF was used to estimate the percentage of an exposed population 
that is likely to exhibit Level B harassment due to 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, a step function at an 
SPL of 140 dB re 1 [mu]Pa was used for beaked whales as the threshold 
to predict Level B harassment by behavioral disturbance.
    Developing the Level B behavioral harassment criteria for Phase III 
(the current phase of Navy training and testing activities) involved 
multiple steps: All available behavioral response studies conducted 
both in the field and on captive animals were examined to understand 
the breadth of behavioral responses of marine mammals to sonar and 
other transducers (See also Navy's Criteria and Thresholds for U.S. 
Navy Acoustic and Explosive Effects Analysis (Phase III) Technical 
Report, 2017). Six behavioral response field studies with observations 
of 14 different marine mammal species reactions to sonar or sonar-like 
signals and 6 captive animal behavioral studies with observations of 8 
different species reactions to sonar or sonar-like signals were used to 
provide a robust data set for the derivation of the Navy's Phase III 
marine mammal behavioral response criteria. All behavioral response 
research that has been published since the derivation of the Navy's 
Phase III criteria (c.a. December 2016) has been examined and is 
consistent with the current behavioral response functions. Marine 
mammal species 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 12 below). This was determined by 
examining all available published field observations of behavioral 
reactions to sonar or sonar-like signals that included the distance 
between the sound source and the marine mammal. The longest distance, 
rounded up to the nearest 5-km increment, was chosen as the cutoff 
distance for each behavioral criteria group (i.e. odontocetes, 
mysticetes, and beaked whales). For animals within the cutoff distance, 
a behavioral response function based on a received SPL as presented in 
Chapter 3, 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 (however, we note that helicopter dipping 
sonars were considered in the intense sound source group, despite lower 
source levels, because of data indicating that marine mammals are 
sometimes more responsive to the less predictable employment of this 
source). There are currently few behavioral observations under these 
circumstances; therefore, the Navy conservatively predicted significant 
behavioral responses that would rise to Level B harassment at farther 
ranges as shown in Table 12, versus less intense events.

  Table 12--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 cutoff       platform cutoff
                                    distance              distance
------------------------------------------------------------------------
Odontocetes.................  10 km...............  20 km.
Mysticetes..................  10 km...............  20 km.
Beaked Whales...............  25 km...............  50 km.
------------------------------------------------------------------------
Note: dB re 1 [micro]Pa @1 m: Decibels referenced to 1 micropascal at 1
  meter; km: Kilometer; SL: Source level.

    The range to received sound levels in 6-dB steps from five 
representative sonar bins and the percentage of animals that may be 
taken by Level B harassment under each behavioral response function are 
shown in Table 13 through Table 17. 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 Chapter 6, Section 6.4.2.1.1 (Methods for 
Analyzing Impacts from Sonars and Other Transducers) of the Navy's 
rulemaking/LOA application for further details on the derivation and 
use of the behavioral response functions,

[[Page 5835]]

thresholds, and the cutoff distances to identify takes by Level B 
harassment, which were coordinated with NMFS. Table 13 illustrates the 
maximum likely percentage of exposed individuals taken at the indicated 
received level and associated range (in which marine mammals would be 
reasonably expected to experience a disruption in behavior patterns to 
a point where they are abandoned or significantly altered) for LFAS. As 
noted previously, NMFS carefully reviewed, and contributed to, the 
Navy's proposed Level B behavioral harassment thresholds and cutoff 
distances for the species, and agrees that these methods represent the 
best available science at this time for determining impacts to marine 
mammals from sonar and other transducers.
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    Table 14. Ranges to estimated Level B behavioral harassment takes 
for sonar bin MF1 over a representative range of environments within 
the MITT Study Area.
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[[Page 5840]]

    Table 17 identifies the maximum likely percentage of exposed 
individuals taken at the indicated received level and associated range 
for HFAS.

 Table 17--Ranges To Estimated Level B Behavioral Harassment Takes for Sonar Bin HF4 Over a Representative Range
                                   of Environments Within the MITT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                   Probability of level B behavioral harassment
                                          Average range (m) with                 for sonar Bin HF4
   Received level (dB re 1 [micro]Pa)      minimum and maximum   -----------------------------------------------
                                          values in parenthesis     Odontocetes                    Beaked whales
                                                                        (%)       Mysticetes (%)        (%)
----------------------------------------------------------------------------------------------------------------
196....................................                  3 (2-4)             100             100             100
190....................................                 8 (6-10)             100              98             100
184....................................               16 (12-20)              99              88             100
178....................................               32 (24-40)              97              59             100
172....................................               63 (45-80)              91              30              99
166....................................             120 (75-160)              78              20              97
160....................................            225 (120-310)              58              18              93
154....................................            392 (180-550)              40              17              83
148....................................          642 (280-1,275)              29              16              66
142....................................          916 (420-1,775)              25              13              45
136....................................        1,359 (625-2,525)              23               9              28
130....................................        1,821 (950-3,275)              20               5              18
124....................................      2,567 (1,275-5,025)              17               2              14
118....................................      3,457 (1,775-6,025)              12               1              12
112....................................      4,269 (2,275-7,025)               6               0              11
106....................................      5,300 (3,025-8,025)               3               0              11
100....................................      6,254 (3,775-9,275)               1               0               8
----------------------------------------------------------------------------------------------------------------
Notes: dB re 1 [micro]Pa = decibels referenced to 1 micropascal, m = meters.

Explosives
    Phase III explosive criteria for Level B behavioral harassment 
thresholds for marine mammals is the hearing groups' TTS threshold 
minus 5 dB (see Table 18 below and Table 11 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. NMFS continues to concur that 
this approach represents the best available science for determining 
impacts to marine mammals from explosives.

  Table 18--Level B Behavioral Harassment Thresholds for Explosives for
                             Marine Mammals
------------------------------------------------------------------------
                                     Functional hearing
              Medium                        group         SEL (weighted)
------------------------------------------------------------------------
Underwater........................  LF..................             163
Underwater........................  MF..................             165
Underwater........................  HF..................             135
------------------------------------------------------------------------
Note: Weighted SEL thresholds in dB re 1 [mu]Pa\2\s underwater.

Navy's Acoustic Effects Model

    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 and each dosimeter records 
its individual sound ``dose.'' The model bases the distribution of 
animats over the MITT 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

[[Page 5841]]

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, 2018).

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 in not only 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 five 
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 13 through Table 17 above, respectively. See Chapter 
6, Section 6.4.2.1 (Methods for Analyzing Impacts from Sonars 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 that are used to identify Level B 
behavioral harassment.
    The ranges to PTS for five representative sonar systems for an 
exposure of 30 seconds is shown in Table 19 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 19--Range to Permanent Threshold Shift (Meters) for Five Representative Sonar Systems
----------------------------------------------------------------------------------------------------------------
                                          Approximate range in meters for PTS from 30 second exposure \1\
          Hearing group          -------------------------------------------------------------------------------
                                   Sonar bin HF4   Sonar bin LF4   Sonar bin MF1   Sonar bin MF4   Sonar bin MF5
----------------------------------------------------------------------------------------------------------------
High-frequency cetaceans........      29 (22-35)         0 (0-0)   181 (180-190)      30 (30-30)        9 (8-10)
Low-frequency cetaceans.........         0 (0-0)         0 (0-0)      65 (65-65)      15 (15-15)         0 (0-0)
Mid-frequency cetaceans.........         1 (0-1)         0 (0-0)      16 (16-16)         3 (3-3)         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 five representative sonar systems (see Table 20 through 
Table 24).

     Table 20--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin LF4 Over a Representative Range of Environments Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Approximate TTS ranges (meters) \1\
                                                     ---------------------------------------------------------------------------------------------------
                    Hearing group                                                                Sonar Bin LF4
                                                     ---------------------------------------------------------------------------------------------------
                                                              1 second                30 seconds               60 seconds              120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................                  0 (0-0)                  0 (0-0)                  0 (0-0)                  0 (0-0)
Low-frequency cetaceans.............................                  3 (3-3)                  4 (4-4)                  6 (6-6)                  9 (9-9)
Mid-frequency cetaceans.............................                  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 MITT 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 21--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin MF1 Over a Representative Range of Environments Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Approximate TTS ranges (meters) \1\
                                                     ---------------------------------------------------------------------------------------------------
                    Hearing group                                                                Sonar Bin MF1
                                                     ---------------------------------------------------------------------------------------------------
                                                              1 second                30 seconds               60 seconds              120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................      3,181 (2,025-5,025)      3,181 (2,025-5,025)      5,298 (2,275-7,775)      6,436 (2,525-9,775)
Low-frequency cetaceans.............................          898 (850-1,025)          898 (850-1,025)      1,271 (1,025-1,525)      1,867 (1,275-3,025)
Mid-frequency cetaceans.............................            210 (200-210)            210 (200-210)            302 (300-310)            377 (370-390)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the MITT 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.
Note: Ranges for 1-second and 30-second periods are identical for Bin MF1 because this system nominally pings every 50 seconds; therefore, these periods
  encompass only a single ping.


[[Page 5842]]


     Table 22--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin MF4 Over a Representative Range of Environments Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Approximate TTS ranges (meters) \1\
                                                     ---------------------------------------------------------------------------------------------------
                    Hearing group                                                                Sonar Bin MF4
                                                     ---------------------------------------------------------------------------------------------------
                                                              1 second                30 seconds               60 seconds              120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................            232 (220-260)            454 (420-600)            601 (575-875)          878 (800-1,525)
Low-frequency cetaceans.............................               85 (85-90)            161 (160-170)            229 (220-250)            352 (330-410)
Mid-frequency cetaceans.............................               22 (22-22)               35 (35-35)               50 (45-50)               70 (70-70)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the MITT 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 23-- Ranges to Temporary Threshold Shift (Meters) for Sonar Bin MF5 Over a Representative Range of Environments Within the MITT Study Area.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Approximate TTS ranges (meters) \1\
                                                     ---------------------------------------------------------------------------------------------------
                    Hearing group                                                                Sonar Bin MF5
                                                     ---------------------------------------------------------------------------------------------------
                                                              1 second                30 seconds               60 seconds              120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................            114 (110-130)            114 (110-130)            168 (150-200)            249 (210-290)
Low-frequency cetaceans.............................               11 (10-12)               11 (10-12)               16 (16-17)               23 (23-24)
Mid-frequency cetaceans.............................                  5 (0-9)                  5 (0-9)               12 (11-13)               18 (17-18)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the MITT 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 24--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin HF4 over a Representative Range of Environments Within the MITT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Approximate TTS ranges (meters) \1\
                                                     ---------------------------------------------------------------------------------------------------
                    Hearing group                                                                Sonar Bin HF4
                                                     ---------------------------------------------------------------------------------------------------
                                                              1 second                30 seconds               60 seconds              120 seconds
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans............................            155 (110-210)            259 (180-350)            344 (240-480)            445 (300-600)
Low-frequency cetaceans.............................                  1 (0-2)                  2 (1-3)                  4 (3-5)                  7 (5-8)
Mid-frequency cetaceans.............................                10 (7-12)               17 (12-21)               24 (17-30)               33 (25-40)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the MITT 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, Section 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, Section 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 25 through 29). Ranges 
are determined by modeling the distance that noise from an explosion 
would need to propagate to reach exposure level thresholds specific to 
a hearing group that would cause behavioral response (to the degree of 
Level B behavioral harassment), 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. Ranges to non-
auditory injury and mortality are shown in Tables 28 and 29, 
respectively. NMFS has reviewed the range distance to effect data 
provided by the Navy and concurs with the analysis. Range to effects is 
important information in not only 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, 2018).
    Table 25 shows the minimum, average, and maximum ranges to onset of 
auditory and likely behavioral effects that rise to the level of Level 
B harassment for high-frequency cetaceans based on the developed 
thresholds.

[[Page 5843]]



               Table 25--SEL-Based Ranges (Meters) to Onset PTS, Onset TTS, and Level B Behavioral Harassment for High-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Range to effects for explosives bin: High-frequency cetaceans \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Source      Cluster
                        Bin                           depth (m)       size               PTS                      TTS                   Behavioral
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1.................................................          0.1            1            353 (340-370)      1,303 (1,275-1,775)      2,139 (2,025-4,275)
                                                     ...........           18      1,031 (1,025-1,275)      3,409 (2,525-8,025)     4,208 (3,025-11,525)
E2.................................................          0.1            1            431 (410-700)      1,691 (1,525-2,775)      2,550 (2,025-4,525)
                                                     ...........            5          819 (775-1,275)      2,896 (2,275-6,775)     3,627 (2,525-10,275)
E3.................................................          0.1            1            649 (625-700)      2,439 (2,025-4,525)      3,329 (2,525-7,525)
                                                     ...........           12      1,682 (1,525-2,275)     4,196 (3,025-11,525)     5,388 (4,525-16,275)
                                                           18.25            1            720 (675-775)      4,214 (2,275-6,275)      7,126 (3,525-8,775)
                                                     ...........           12      1,798 (1,525-2,775)    10,872 (4,525-13,775)    14,553 (5,525-17,775)
E4.................................................           10            2      1,365 (1,025-2,775)     7,097 (4,275-10,025)     9,939 (5,025-15,275)
                                                              60            2        1,056 (875-2,275)      3,746 (2,775-5,775)      5,262 (3,025-7,775)
E5.................................................          0.1           20      2,926 (1,525-6,275)     6,741 (4,525-16,025)     9,161 (4,775-20,025)
                                                              30           20      4,199 (3,025-6,275)    13,783 (8,775-17,775)   17,360 (10,525-22,775)
E6.................................................          0.1            1      1,031 (1,025-1,275)      3,693 (2,025-8,025)     4,659 (3,025-12,775)
                                                              30            1      1,268 (1,025-1,275)      7,277 (3,775-8,775)    10,688 (5,275-12,525)
E7.................................................           28            1      1,711 (1,525-2,025)     8,732 (4,275-11,775)    12,575 (4,275-16,025)
E8.................................................          0.1            1      1,790 (1,775-3,025)     4,581 (4,025-10,775)     6,028 (4,525-15,775)
                                                           45.75            1      1,842 (1,525-2,025)     9,040 (4,525-12,775)    12,729 (5,025-18,525)
E9.................................................          0.1            1      2,343 (2,275-4,525)     5,212 (4,025-13,275)     7,573 (5,025-17,025)
E10................................................          0.1            1      2,758 (2,275-5,025)     6,209 (4,275-16,525)     8,578 (5,275-19,775)
E11................................................        45.75            1      3,005 (2,525-3,775)    11,648 (5,025-18,775)    14,912 (6,525-24,775)
                                                            91.4            1      3,234 (2,525-4,525)     5,772 (4,775-11,775)     7,197 (5,775-14,025)
E12................................................          0.1            1      3,172 (3,025-6,525)     7,058 (5,025-17,025)     9,262 (6,025-21,775)
                                                     ...........            4     4,209 (3,775-10,025)     9,817 (6,275-22,025)    12,432 (7,525-27,775)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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.

    Table 26 shows the minimum, average, and maximum ranges to onset of 
auditory and likely behavioral effects that rise to the level of Level 
B harassment for mid-frequency cetaceans based on the developed 
thresholds.

               Table 26--SEL-Based Ranges (Meters) to Onset PTS, Onset TTS, and Level B Behavioral Harassment for Mid-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Range to effects for explosives bin: Mid-frequency cetaceans \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Source      Cluster
                        Bin                           depth (m)       size               PTS                      TTS                   Behavioral
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1.................................................          0.1            1               25 (25-25)            116 (110-120)            199 (190-210)
                                                     ...........           18              94 (90-100)            415 (390-440)            646 (525-700)
E2.................................................          0.1            1               30 (30-35)            146 (140-170)            248 (230-370)
                                                     ...........            5               63 (60-70)            301 (280-410)            481 (430-675)
E3.................................................          0.1            1               50 (50-50)            233 (220-250)            381 (360-400)
                                                     ...........           12            155 (150-160)            642 (525-700)          977 (700-1,025)
                                                           18.25            1               40 (40-40)            202 (190-220)            332 (320-350)
                                                     ...........           12            126 (120-130)            729 (675-775)      1,025 (1,025-1,025)
E4.................................................           10            2               76 (70-90)            464 (410-550)            783 (650-975)
                                                              60            2               60 (60-60)            347 (310-675)            575 (525-900)
E5.................................................          0.1           20            290 (280-300)        1,001 (750-1,275)        1,613 (925-3,275)
                                                              30           20            297 (240-420)      1,608 (1,275-2,775)      2,307 (2,025-2,775)
E6.................................................          0.1            1              98 (95-100)            430 (400-450)            669 (550-725)
                                                              30            1               78 (75-80)            389 (370-410)            619 (600-650)
E7.................................................           28            1            110 (110-110)            527 (500-575)      1,025 (1,025-1,025)
E8.................................................          0.1            1            162 (150-170)            665 (550-700)          982 (725-1,025)
                                                           45.75            1            127 (120-130)            611 (600-625)          985 (950-1,025)
E9.................................................          0.1            1            215 (210-220)          866 (625-1,000)        1,218 (800-1,525)
E10................................................          0.1            1            270 (250-280)          985 (700-1,275)        1,506 (875-2,525)
E11................................................        45.75            1            241 (230-250)      1,059 (1,000-1,275)      1,874 (1,525-2,025)
                                                            91.4            1            237 (230-270)        1,123 (900-2,025)      1,731 (1,275-2,775)
E12................................................          0.1            1            332 (320-370)        1,196 (825-1,525)      1,766 (1,025-3,525)
                                                     ...........            4            572 (500-600)      1,932 (1,025-4,025)      2,708 (1,275-6,775)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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.


[[Page 5844]]

    Table 27 shows the minimum, average, and maximum ranges to onset of 
auditory and likely behavioral effects that rise to the level of Level 
B harassment for low-frequency cetaceans based on the developed 
thresholds.

               Table 27--SEL-Based Ranges (Meters) to Onset PTS, Onset TTS, and Level B Behavioral Harassment for Low-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Range to effects for explosives bin: Low-frequency cetaceans \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Source      Cluster
                        Bin                           depth (m)       size               PTS                      TTS                   Behavioral
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1.................................................          0.1            1               51 (50-55)            231 (200-250)            378 (280-410)
                                                     ...........           18            183 (170-190)            691 (450-775)          934 (575-1,275)
E2.................................................          0.1            1               66 (65-70)            291 (220-320)            463 (330-500)
                                                     ...........            5            134 (110-140)            543 (370-600)            769 (490-950)
E3.................................................          0.1            1            113 (110-120)            477 (330-525)            689 (440-825)
                                                     ...........           12            327 (250-370)          952 (600-1,525)        1,240 (775-4,025)
                                                           18.25            1            200 (200-200)          955 (925-1,000)      1,534 (1,275-1,775)
                                                     ...........           12            625 (600-625)      5,517 (2,275-7,775)    10,299 (3,775-13,025)
E4.................................................           10            2            429 (370-600)      2,108 (1,775-2,775)      4,663 (3,025-6,025)
                                                              60            2            367 (340-470)      1,595 (1,025-2,025)      2,468 (1,525-4,275)
E5.................................................          0.1           20          702 (380-1,275)       1,667 (850-11,025)     2,998 (1,025-19,775)
                                                              30           20      1,794 (1,275-2,775)     8,341 (3,775-11,525)    13,946 (4,025-22,275)
E6.................................................          0.1            1            250 (190-410)          882 (480-1,775)        1,089 (625-6,525)
                                                              30            1            495 (490-500)      2,315 (2,025-2,525)      5,446 (3,275-6,025)
E7.................................................           28            1            794 (775-900)      4,892 (2,775-6,275)     9,008 (3,775-12,525)
E8.................................................          0.1            1            415 (270-725)        1,193 (625-4,275)        1,818 (825-8,525)
                                                           45.75            1            952 (900-975)      6,294 (3,025-9,525)    12,263 (4,275-20,025)
E9.................................................          0.1            1          573 (320-1,025)        1,516 (725-7,275)       2,411 (950-14,275)
E10................................................          0.1            1          715 (370-1,525)       2,088 (825-28,275)     4,378 (1,025-32,275)
E11................................................        45.75            1      1,881 (1,525-2,275)    12,425 (4,275-27,275)    23,054 (7,025-65,275)
                                                            91.4            1      1,634 (1,275-2,525)     5,686 (3,775-11,275)    11,618 (5,525-64,275)
E12................................................          0.1            1          790 (420-2,775)       2,698 (925-25,275)     6,032 (1,025-31,275)
                                                     ...........            4        1,196 (575-6,025)     6,876 (1,525-31,275)    13,073 (3,775-64,275)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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.

    Table 28 shows 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). Ranges to 
gastrointestinal tract injury typically exceed ranges to slight lung 
injury; therefore, the maximum range to effect is not mass-dependent. 
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 28--Ranges \1\ to 50 Percent Non-Auditory Injury Risk for All
                      Marine Mammal Hearing Groups
------------------------------------------------------------------------
                                                         Range (m) (min-
                          Bin                                 max)
------------------------------------------------------------------------
E1....................................................        12 (11-13)
E2....................................................        16 (15-16)
E3....................................................        25 (25-25)
E4....................................................        30 (30-35)
E5....................................................        40 (40-65)
E6....................................................        52 (50-60)
E7....................................................     120 (120-120)
E8....................................................       98 (90-150)
E9....................................................     123 (120-270)
E10...................................................     155 (150-430)
E11...................................................     418 (410-420)
E12...................................................     195 (180-675)
------------------------------------------------------------------------
\1\ Distances in meters (m). Average distance is shown with the minimum
  and maximum distances due to varying propagation environments in
  parentheses.
Note: All ranges to non-auditory injury within this table are driven by
  gastrointestinal tract injury thresholds regardless of animal mass.

    Ranges to mortality, based on animal mass, are shown in Table 29 
below.

                   Table 29--Ranges \1\ to 50 Percent Mortality Risk for All Marine Mammal Hearing Groups as a Function of Animal Mass
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Range to mortality (meters) for various animal mass intervals (kg) \1\
                           Bin                           -----------------------------------------------------------------------------------------------
                                                                10              250            1,000           5,000          25,000          72,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1......................................................         3 (3-3)         1 (0-2)         0 (0-0)         0 (0-0)         0 (0-0)         0 (0-0)
E2......................................................         4 (3-4)         2 (1-3)         1 (0-1)         0 (0-0)         0 (0-0)         0 (0-0)
E3......................................................        9 (7-10)         4 (2-8)         2 (1-2)         1 (0-1)         0 (0-0)         0 (0-0)
E4......................................................      13 (12-15)        7 (4-12)         3 (3-4)         2 (1-3)         1 (1-1)         1 (0-1)
E5......................................................      13 (12-30)        7 (4-25)         3 (2-7)         2 (1-5)         1 (1-2)         1 (0-2)
E6......................................................      16 (15-25)        9 (5-23)         4 (3-8)         3 (2-6)         1 (1-2)         1 (1-2)
E7......................................................      55 (55-55)      26 (18-40)      13 (11-15)        9 (7-10)         4 (4-4)         3 (2-3)
E8......................................................      42 (25-65)       22 (9-50)       11 (6-19)        8 (4-13)         4 (2-6)         3 (1-5)
E9......................................................      33 (30-35)      20 (13-30)       10 (9-12)         7 (5-9)         4 (3-4)         3 (2-3)

[[Page 5845]]

 
E10.....................................................     55 (40-170)      24 (16-35)      13 (11-15)        9 (7-11)         5 (4-5)         4 (3-4)
E11.....................................................   206 (200-210)     98 (55-170)      44 (35-50)      30 (25-35)      16 (14-18)      12 (10-15)
E12.....................................................     86 (50-270)     35 (20-210)      16 (13-19)       11 (9-13)         6 (5-6)         5 (4-5)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (m) to mortality is depicted above the minimum and maximum distances, which are in parentheses.

Marine Mammal Density

    A quantitative analysis of impacts on a species or stock 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 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 broad geographic 
areas. This is the general approach applied in estimating cetacean 
abundance in NMFS' Stock Assessment Reports (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 or seasons that were not 
surveyed. More recently, spatial habitat modeling developed by NMFS' 
Southwest Fisheries Science Center has been used to estimate cetacean 
densities (Barlow et al., 2009; Becker et al., 2010, 2012a, b, c, 2014, 
2016; Ferguson et al., 2006a; 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.
    Ideally, density data would be available for all species throughout 
the study area year-round, in order to best estimate the impacts of 
Navy activities on marine species. However, in many places, ship 
availability, lack of funding, inclement weather conditions, and high 
sea states prevent the completion of comprehensive year-round surveys. 
Even with surveys that are completed, poor conditions may result in 
lower sighting rates for species that would typically be sighted with 
greater frequency under favorable conditions. Lower sighting rates 
preclude having an acceptably low uncertainty in the density estimates. 
A high level of uncertainty, indicating a low level of confidence in 
the density estimate, is typical for species that are rare or difficult 
to sight. In areas where survey data are limited or non-existent, known 
or inferred associations between marine habitat features and the likely 
presence of specific species are sometimes used to predict densities in 
the absence of actual animal sightings. Consequently, there is no 
single source of density data for every area, species, and season 
because of the fiscal costs, resources, and effort involved in 
providing enough survey coverage to sufficiently estimate density.
    To characterize marine species density for large oceanic regions, 
the Navy reviews, critically assesses, and prioritizes existing density 
estimates from multiple sources, requiring the development of a 
systematic method for selecting the most appropriate density estimate 
for each combination of species, area, and season. The selection and 
compilation of the best available marine species density data resulted 
in the Navy Marine Species Density Database (NMSDD). NMFS vetted all 
cetacean densities by the Navy prior to use in the Navy's acoustic 
analysis for the current MITT rulemaking process.
    In the MITT Study Area there is a paucity of line-transect survey 
data, and little is known about the stock structure of the majority of 
marine mammal species in the region. The Navy conducted the first 
comprehensive marine mammal survey of waters off Guam and the 
Commonwealth of the Northern Mariana Islands in 2007, and data from 
this survey were used to derive line-transect abundance estimates for 
12 cetacean species (Fulling et al., 2011). There has not been a 
subsequent systematic survey of the MITT Study Area at this scale, so 
these data still provide the best available density estimates for this 
region.
    In the absence of study-area-specific density data, line-transect 
estimates derived for Hawaiian waters were used to provide conservative 
density estimates for the MITT Study Area. For Phase II, these 
estimates were based on systematic surveys conducted by NMFS' Southwest 
Fisheries Science Center (SWFSC) within the Exclusive Economic Zone of 
the Hawaiian Islands in 2002 (Barlow, 2006). New survey data collected 
within the Exclusive Economic Zone of the Hawaiian Islands (2010) and 
Palmyra Atoll/Kingman Reef (2011-2012) allowed NMFS' Pacific Islands 
Fisheries Science Center (PIFSC) to update the line-transect density 
estimates that included new sea-state-specific estimates of trackline 
detection probability (Bradford et al., 2017) and represent 
improvements to the estimates used for Phase II. In addition, an 
updated density estimate for minke whale was available for Phase III 
based on line-transect analyses of acoustic data collected from a towed 
hydrophone during the 2007 systematic survey (Norris et al., 2017). 
Finally, a habitat model was developed for sperm whale based on 
acoustic data collected during the 2007 survey, and provided spatially 
explicit density predictions at a10 km x 10 km (100 square km) spatial 
resolution (Yack et al., 2016).

[[Page 5846]]

    To characterize the marine species density for large areas, 
including the MITT 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, used in the NMSDD, includes 
seasonal density values for every marine mammal species present within 
the MITT Study Area. This database is described in the technical report 
titled U.S. Navy Marine Species Density Database Phase III for the 
Mariana Islands Training and Testing Study Area (U.S. Department of the 
Navy, 2018), 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 MITT 
Study Area. Because this data is collected using different methods with 
varying amounts of accuracy and uncertainty, the Navy has developed a 
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 list below 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; therefore, this model 
cannot be used for species with low numbers of sightings.
    2. Stratified design-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.
    The Navy describes some of the challenges of interpreting the 
results of the quantitative analysis summarized above and 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).''
    NMFS coordinated with the Navy in the development of its take 
estimates and concurs that the Navy's approach for density 
appropriately utilizes the best available science. Later, in the 
Preliminary Analysis and Negligible Impact Determination section, we 
assess how the estimated take numbers compare to 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 2019 MITT DSEIS/OEIS considered all training and testing 
activities proposed to occur in the MITT Study Area that have the 
potential to result in the MMPA defined take of marine mammals. The 
Navy determined that the two stressors below 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 by 
harassment of marine mammals from the Navy's planned activities.
    [ssquf] Acoustics (sonar and other transducers);
    [ssquf] Explosives (explosive shock wave and sound, assumed to 
encompass the risk due to fragmentation).
    The quantitative analysis process used for the 2019 MITT DSEIS/OEIS 
and the Navy's take 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 (U.S. 
Department of the Navy, 2018). 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 procedural mitigation is expected to reduce the risk for 
model-estimated PTS for exposures to sonars and for model-estimated 
mortality for exposures to explosives, based on species sightability, 
observation area, visibility, and the ability to exercise positive 
control over the sound source. Where the analysis indicates mitigation 
would effectively reduce risk, the model-estimated PTS are considered 
reduced to TTS and the model-estimated mortalities are considered 
reduced to injury. For a complete explanation of the process for 
assessing the effects of mitigation, see the Navy's rulemaking/LOA 
application and the technical report titled Quantifying Acoustic 
Impacts on Marine Mammals and Sea Turtles: Methods and Analytical 
Approach for Phase III Training and Testing (U.S. Department of the 
Navy, 2018). The extent to which the mitigation areas reduce impacts on 
the affected species is addressed separately in the Preliminary 
Analysis and Negligible Impact Determination section.
    The Navy assessed the effectiveness of its procedural 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

[[Page 5847]]

could potentially be conducted at night, and (4) the ability for sound 
sources to be positively controlled (e.g., powered down).
    During 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 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 
procedural mitigation.
[GRAPHIC] [TIFF OMITTED] TP31JA20.006

    Species Sightability is the ability to detect marine mammals and 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 the standard ``detection probability'' referred to as g(0) 
is most appropriate. 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 (U.S. Department of the Navy, 2018).
    To quantify the number of marine mammals predicted to be sighted by 
Lookouts in the injury zone during implementation of procedural 
mitigation 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:
[GRAPHIC] [TIFF OMITTED] TP31JA20.007

    The marine mammals sighted by Lookouts in the injury zone during 
implementation of mitigation, as calculated by the equation above, 
would avoid being exposed to these higher level impacts. To quantify 
the number of marine mammals predicted to be sighted by Lookouts in the 
mortality zone during implementation of procedural mitigation 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 predicted to 
be sighted in the mortality zone by Lookouts during implementation of 
procedural mitigation, 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.
    The NAEMO (animal movement) model overestimates the number of 
marine mammals that would be exposed to sound sources that could cause 
PTS because the model does not consider horizontal movement of animats, 
including avoidance of high intensity sound exposures. Therefore, the 
potential for animal avoidance is considered separately. At close 
ranges and high sound levels, avoidance of the area immediately around 
the sound source is one of the assumed behavioral responses for marine 
mammals. Animal avoidance refers to the movement out of the immediate 
injury zone for subsequent exposures, not wide-scale area avoidance. 
Various researchers have demonstrated that cetaceans can perceive the 
location and movement of a sound source (e.g., vessel, seismic source, 
etc.) relative to their own location and react with responsive movement 
away from the source, often at distances of 1 km or more (Au & 
Perryman,1982; Jansen et al., 2010; Richardson et al., 1995; Tyack et 
al., 2011; Watkins, 1986; W[uuml]rsig et al., 1998) A marine mammal's 
ability to avoid a sound source and reduce its cumulative sound energy 
exposure would reduce risk of both PTS and TTS. However, the 
quantitative analysis conservatively only considers the potential to 
reduce some instances of PTS by accounting for marine mammals swimming 
away to avoid repeated high-level sound exposures. All reductions in 
PTS impacts from likely avoidance behaviors are instead considered TTS 
impacts.

[[Page 5848]]

    NMFS coordinated with the Navy in the development of this 
quantitative method to address the effects of procedural mitigation on 
acoustic and explosive exposures and takes, and NMFS independently 
reviewed and concurs with the Navy that it is appropriate to 
incorporate the quantitative assessment of mitigation 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 (U.S. Department of the 
Navy, 2018) and Chapter 6 (Take Estimates for Marine Mammals) and 
Chapter 11 (Mitigation Measures) of the Navy's rulemaking/LOA 
application.
    As a general matter, NMFS does not prescribe the methods for 
estimating take for any applicant, but we review and ensure that 
applicants use the best available science, and methodologies that are 
logical and technically sound. Applicants may use different methods of 
calculating take (especially when using models) and still get to a 
result that is representative of the best available science and that 
allows for a rigorous and accurate evaluation of the effects on the 
affected populations. There are multiple pieces of the Navy take 
estimation methods--propagation models, animat movement models, and 
behavioral thresholds, for example. NMFS evaluates the acceptability of 
these pieces as they evolve and are used in different rules and impact 
analyses. Some of the pieces of the Navy's take estimation process have 
been used in Navy incidental take rules since 2009 and undergone 
multiple public comment processes, all of them have undergone extensive 
internal Navy review, and all of them have undergone comprehensive 
review by NMFS, which has sometimes resulted in modifications to 
methods or models.
    The Navy uses rigorous review processes (verification, validation, 
and accreditation processes, peer and public review) to ensure the data 
and methodology it uses represent the best available science. For 
instance, the NAEMO model is the result of a NMFS-led Center for 
Independent Experts (CIE) review of the components used in earlier 
models. The acoustic propagation component of the NAEMO model (CASS/
GRAB) is accredited by the Oceanographic and Atmospheric Master Library 
(OAML), and many of the environmental variables used in the NAEMO model 
come from approved OAML databases and are based on in-situ data 
collection. The animal density components of the NAEMO model are base 
products of the NMSDD, which includes animal density components that 
have been validated and reviewed by a variety of scientists from NMFS 
Science Centers and academic institutions. Several components of the 
model, for example the Duke University habitat-based density models, 
have been published in peer reviewed literature. Others like the 
Atlantic Marine Assessment Program for Protected Species, which was 
conducted by NMFS Science Centers, have undergone quality assurance and 
quality control (QA/QC) processes. Finally the NAEMO model simulation 
components underwent QA/QC review and validation for model parts such 
as the scenario builder, acoustic builder, scenario simulator, etc., 
conducted by qualified statisticians and modelers to ensure accuracy. 
Other models and methodologies have gone through similar review 
processes.
    In summary, we believe the Navy's methods, including the method for 
incorporating mitigation and avoidance, are the most appropriate 
methods for predicting PTS, TTS, and behavioral disruption. But even 
with the consideration of mitigation and avoidance, given some of the 
more conservative components of the methodology (e.g., the thresholds 
do not consider ear recovery between pulses), we would describe the 
application of these methods as identifying the maximum number of 
instances in which marine mammals would be reasonably expected to be 
taken through PTS, TTS, or behavioral disruption.
Summary of Requested Take From Training and Testing Activities
    Based on the methods discussed in the previous sections and the 
Navy's model and quantitative assessment of mitigation, the Navy 
provided its take estimate and request for authorization of takes 
incidental to the use of acoustic and explosive sources for training 
and testing activities both annually (based on the maximum number of 
activities that could occur per 12-month period) and over the seven-
year period covered by the Navy's rulemaking/LOA application. NMFS has 
reviewed the Navy's data, methodology, and analysis and determined that 
it is complete and accurate. NMFS agrees that the estimates for 
incidental takes by harassment from all sources requested for 
authorization are the maximum number of instances in which marine 
mammals are reasonably expected to be taken.
    For training and testing activities, Table 30 summarizes the Navy's 
take estimate and request and the annual and maximum amount and type of 
Level A harassment and Level B harassment for the seven-year period 
that NMFS concurs is reasonably expected to occur by species. Note that 
take by Level B harassment includes both behavioral disruption and TTS. 
Tables 6.4-13 through 6.4-38 in Section 6 of the Navy's rulemaking/LOA 
application provide the comparative amounts of TTS and behavioral 
disruption for each species annually, noting that if a modeled marine 
mammal was ``taken'' through exposure to both TTS and behavioral 
disruption in the model, it was recorded as a TTS.

 Table 30--Annual and Seven-Year Total Species-Specific Take Estimates Proposed for Authorization From Acoustic
        and Explosive Sound Source Effects for All Training and Testing Activities in the MITT Study Area
----------------------------------------------------------------------------------------------------------------
                                                              Annual                     7-Year Total \1\
                     Species                     ---------------------------------------------------------------
                                                      Level B         Level A         Level B         Level A
----------------------------------------------------------------------------------------------------------------
                                                   Mysticetes
----------------------------------------------------------------------------------------------------------------
Blue whale *....................................              24               0             169               0
Bryde's whale...................................             298               0           2,078               0
Fin whale *.....................................              25               0             173               0
Humpback whale *................................             479               0           3,348               0
Minke whale.....................................              95               0             665               0
Omura's whale...................................              29               0             199               0

[[Page 5849]]

 
Sei whale *.....................................             155               0           1,083               0
----------------------------------------------------------------------------------------------------------------
                                                   Odontocetes
----------------------------------------------------------------------------------------------------------------
Blainville's beaked whale.......................           1,718               0          12,033               0
Bottlenose dolphin..............................             137               0             961               0
Cuvier's beaked whale...........................             646               0           4,529               0
Dwarf sperm whale...............................           8,499              50          59,459             341
False killer whale..............................             762               0           5,331               0
Fraser's dolphin................................          13,278               1          92,931               8
Ginkgo-toothed beaked whale.....................           3,726               0          26,088               0
Killer whale....................................              44               0             309               0
Longman's beaked whale..........................           6,066               0          42,487               0
Melon-headed whale..............................           2,815               0          19,691               0
Pantropical spotted dolphin.....................          14,896               1         104,242               7
Pygmy killer whale..............................             104               0             726               0
Pygmy sperm whale...............................           3,410              19          23,853             136
Risso's dolphin.................................           3,170               0          22,179               0
Rough-toothed dolphin...........................             197               0           1,379               0
Short-finned pilot whale........................           1,163               0           8,140               0
Sperm whale *...................................             203               0           1,420               0
Spinner dolphin.................................           1,414               1           9,896               4
Striped dolphin.................................           4,007               0          28,038               0
----------------------------------------------------------------------------------------------------------------
*ESA-listed species within the MITT Study Area
\1\The 7-year totals may be less than the annual totals times seven, given that not all activities occur every
  year, some activities occur multiple times within a year, and some activities only occur a few times over the
  course of a 7-year period.

Proposed Mitigation Measures

    Under section 101(a)(5)(A) of the MMPA, NMFS must set forth the 
permissible methods of taking pursuant to the activity, and other means 
of effecting the least practicable adverse impact on the species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance, and on the 
availability of the species or stocks for subsistence uses (``least 
practicable adverse impact''). NMFS does not have a regulatory 
definition for least practicable adverse impact. The 2004 NDAA 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] satisfies] 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 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 practicable adverse impact' standard.'' As 
the Ninth Circuit noted in its opinion, however, the Court was 
interpreting the statute without the benefit of NMFS' 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 previous rules we have issued, such 
as the Navy's HSTT rule (83 FR 66846; December 27, 2018) and Atlantic 
Fleet Training and Testing rule (83 FR 57076; November 14, 2018).
    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' 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 \1\ and, therefore are considered in 
evaluating population level impacts.
---------------------------------------------------------------------------

    \1\ A growth rate can be positive, negative, or flat.
---------------------------------------------------------------------------

    As stated in the preamble to the proposed rule for the MMPA 
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).

[[Page 5850]]

    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.\2\
---------------------------------------------------------------------------

    \2\ 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). Section 3(11) of 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. 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 
definitions involving groups of individuals that belong to the same 
species and that are located in a manner that allows for interbreeding. 
In fact under MMPA section 3(11), the term ``stock'' in the MMPA is 
interchangeable with the statutory term ``population stock.'' Both the 
negligible impact standard and the least practicable adverse impact 
standard call for evaluation at the level of the species or stock, and 
the terms ``species'' and ``stock'' both relate to populations; 
therefore, it is appropriate to view both the negligible impact 
standard and the least practicable adverse impact standard as having a 
population-level focus.
    This interpretation is consistent with Congress' statutory findings 
for enacting the MMPA, nearly all of which are most applicable at the 
species or stock (i.e., population) level. See MMPA section 2 (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, 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.\3\ 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 military readiness needs.'' 
Pritzker 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.
---------------------------------------------------------------------------

    \3\ 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).
---------------------------------------------------------------------------

    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.

[[Page 5851]]

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 Preliminary Analysis and 
Negligible Impact Determination section 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 activities, 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.
    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' analysis focuses on 
measures that are designed to avoid or minimize impacts on individual 
marine mammals that are likely to increase the probability or severity 
of population-level effects.
    While direct evidence of impacts to species or stocks from a 
specified activity is rarely available, and additional study is still 
needed to understand how specific disturbance events affect the fitness 
of individuals of certain species, there have been 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 
often be inferred given a detailed understanding of the activity, the 
environment, and the affected species or stocks--and the best available 
science has been used here. This same information is used in the 
development of mitigation measures and helps us understand how 
mitigation measures contribute to lessening effects (or the risk 
thereof) to species or stocks. We also acknowledge that there is always 
the potential that new information, or a new recommendation could 
become available in the future and necessitate 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 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 its 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. We discuss consideration of these factors in 
greater detail below.
    1. Reduction of adverse impacts to marine mammal species or stocks 
and their habitat.\4\ 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.
---------------------------------------------------------------------------

    \4\ 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 appropriate mitigation measures and because the focus 
of the standard is on reducing impacts at the species or stock level, 
the least practicable adverse impact standard does not compel 
mitigation for every kind of take, or

[[Page 5852]]

every individual taken, if that mitigation is unlikely to meaningfully 
contribute to the reduction of adverse impacts on the species or stock 
and its habitat, 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 MMPA section 3(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 
activities, and, in the case of a military readiness activity, will 
include personnel safety, practicality of implementation, and impact on 
the effectiveness of the military readiness activity (see MMPA section 
101(a)(5)(A)(ii)).

Assessment of Mitigation Measures for the MITT Study Area

    NMFS has fully reviewed the specified activities and the mitigation 
measures included in the Navy's rulemaking/LOA application and the 2019 
MITT DSEIS/OEIS to determine if the mitigation measures would result in 
the least practicable adverse impact on marine mammals and their 
habitat. 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 Navy's 
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 I (Geographic Mitigation 
Assessment) of the 2019 MITT DSEIS/OEIS. The process described in 
Chapter 5 (Mitigation) and Appendix I (Geographic Mitigation 
Assessment) of the 2019 MITT DSEIS/OEIS robustly supported NMFS' 
independent evaluation of whether the mitigation measures would meet 
the least practicable adverse impact standard. The Navy would be 
required to implement the mitigation measures identified in this rule 
for the full seven years to avoid or reduce potential impacts from 
acoustic and explosive stressors.
    As a general matter, where an applicant proposes measures that are 
likely to reduce impacts to marine mammals, the fact that they are 
included in the application indicates that the measures are 
practicable, and it is not necessary for NMFS to conduct a detailed 
analysis of the measures the applicant proposed (rather, they are 
simply included). We note that in their application, the Navy added 
three geographic mitigation measures that are new since the 2015-2020 
MITT incidental take regulations: (1) Marpi Reef Geographic Mitigation 
Area--to avoid potential impacts from explosives on marine mammals and 
report hours of MFAS-MF1 within the mitigation area, which contains a 
seasonal presence of humpback whales (2) Chalan Kanoa Reef Geographic 
Mitigation Area--to avoid potential impacts from explosives on marine 
mammals and report hours of MFAS-MF1 within the mitigation area, which 
contains a seasonal presence of humpback whales and (3) Agat Bay 
Nearshore Geographic Mitigation Area--to avoid potential impacts from 
explosives and MFAS-MF1 on spinner dolphins. However, it is still 
necessary for NMFS to consider whether there are additional practicable 
measures that would meaningfully reduce the probability or severity of 
impacts that could affect reproductive success or survivorship. In the 
case of this rule, we worked with the Navy after it submitted its 2019 
rulemaking/LOA application but prior to the development of this 
proposed rule and the Navy also agreed to expand the geographic 
mitigation areas for Marpi Reef and Chalan Kanoa Reef Geographic 
Mitigation Areas to more fully encompass the 400 m isobaths based on 
the available data indicating the presence of humpback whale mother/
calf pairs (seasonal breeding area), which is expected to further avoid 
impacts from explosives that would be more likely to affect 
reproduction or survival of individuals and could adversely impact the 
species. The Navy also agreed to the addition of the Marpi Reef and 
Chalan Kanoa Reef Awareness Notification Message Areas, which allow 
Navy personnel to inform other personnel of the presence of humpback 
whales, enabling them to avoid potential impacts from vessel strikes 
and training and testing activities as these areas contain important 
seasonal breeding habitat for this species.
    Overall the Navy has agreed to procedural mitigation measures that 
would 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 
avoid mortality or serious injury, 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 would also implement multiple time/area restrictions that would 
reduce take of marine mammals in areas or at times where they are known 
to engage in important behaviors, such as 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. Summaries of the Navy's procedural mitigation 
measures and mitigation areas for the MITT Study Area are provided in 
Tables 31 and 32.

[[Page 5853]]



               Table 31--Summary of Procedural Mitigation
------------------------------------------------------------------------
                                    Mitigation zone sizes and other
     Stressor or activity                     requirements
------------------------------------------------------------------------
Environmental Awareness and    Afloat Environmental Compliance Training
 Education.                     program for applicable personnel.
Active Sonar.................  Depending on sonar source: 1,000 yd power
                                down, 500 yd power down, and 200 yd shut
                                down.
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   1,000 yd (large-caliber projectiles), 600
 Large-Caliber Projectiles.     yd. (medium-caliber projectiles during
                                surface-to-surface activities), or 200
                                yd. (medium-caliber projectiles during
                                air-to-surface activities).
Explosive Missiles and         2,000 yd (>21-500 lb net explosive
 Rockets.                       weight), or 900 yd (0.6-20 lb net
                                explosive weight).
Explosive Bombs..............  2,500 yd.
Sinking Exercises............  2.5 NM.
Explosive Mine Countermeasure  600 yd.
 and Neutralization
 Activities.
Explosive Mine Neutralization  1,000 yd (charges using time delay
 Activities involving Navy      fuses), or 500 yd (positive control
 Divers.                        charges).
Maritime Security Operations-- 200 yd.
 Anti-Swimmer Grenades.
Vessel Movement..............  500 yd (whales) or 200 yd (other marine
                                mammals).
Towed In-Water Devices.......  250 yd.
Small-, Medium-, and Large-    200 yd.
 Caliber Non-Explosive
 Practice Munitions.
Non-Explosive Missiles and     900 yd.
 Rockets.
Non-Explosive Bombs and Mine   1,000 yd.
 Shapes.
------------------------------------------------------------------------
Notes: lb: Pounds; NM: Nautical miles; yd: Yards


        Table 32--Summary of Mitigation Areas for Marine Mammals
------------------------------------------------------------------------
  Geographic mitigation area     Approximate area
             name                    (km\2\)         Summary of actions
------------------------------------------------------------------------
Marpi Reef...................  33.................  Humpback whales
                                                     (seasonally)
                                                     reporting MFAS-MF1;
                                                     no explosives year-
                                                     round.
Chalan Kanoa Reef............  102................  Humpback whales
                                                     (seasonally)
                                                     reporting MFAS-MF1;
                                                     no explosives year-
                                                     round.
Agat Bay Nearshore...........  5..................  No MFAS- MF1 sonar
                                                     or explosive year-
                                                     round.
Marpi Reef and Chalan Kanoa    33 and 102.........  Inform personnel to
 Reef Notification Awareness                         the presence of
 Message Areas.                                      humpback whales
                                                     enabling them to
                                                     avoid potential
                                                     impacts from vessel
                                                     strikes and
                                                     training and
                                                     testing activities.
------------------------------------------------------------------------

    The Navy assessed the practicability of the proposed measures 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 are supportable. As described in more 
detail below, NMFS has independently evaluated the measures the Navy 
proposed in the manner described earlier in this section (i.e., in 
consideration of their ability to reduce adverse impacts on marine 
mammal species and their habitat and their practicability for 
implementation). We have determined that the measures will 
significantly and adequately reduce impacts on the affected marine 
mammal species and their habitat and, further, 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 their habitat.
    The Navy also evaluated numerous measures in the 2019 MITT DSEIS/
OEIS that were not included in the Navy's rulemaking/LOA application, 
and NMFS independently reviewed and 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 
considered these additional potential mitigation measures in two 
groups. First, Chapter 5 (Mitigation) of the 2019 MITT DSEIS/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 non-governmental organizations or the public, through 
scoping or public comment on environmental compliance documents. 
Appendix I (Geographic Mitigation Assessment) of the 2019 MITT DSEIS/
OEIS includes an in-depth analysis of time/area restrictions that have 
been recommended over time or previously implemented as a result of 
litigation (outside of the MITT Study Area). As described in Chapter 5 
(Mitigation) of the 2019 MITT DSEIS/OEIS, commenters sometimes 
recommend that the Navy reduce its overall amount of training, reduce 
explosive use, modify its sound sources, completely replace live 
training with computer simulation, or include time of day restrictions. 
Many of these mitigation 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 described in 
Chapter 5 (Mitigation) of the 2019 MITT DSEIS/OEIS, the Navy needs to 
train and test in the conditions in which it fights--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. After independent review, NMFS finds Navy's 
judgment on the impacts of potential mitigation measures to personnel 
safety, practicality of implementation, and the effectiveness of 
training and testing within the MITT Study Area persuasive, and for 
these

[[Page 5854]]

reasons, NMFS finds that these measures do not meet the least 
practicable adverse impact standard because they are not practicable.
    Second, in Chapter 5 (Mitigation) of the 2019 MITT DSEIS/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 measures would have significant direct 
negative effects on mission effectiveness and are considered 
impracticable (see Chapter 5 Mitigation of 2019 MITT DSEIS/OEIS). NMFS 
independently reviewed the Navy's evaluation and concurs with this 
assessment, which supports NMFS' preliminary findings that the 
impracticability of this additional mitigation would greatly outweigh 
any potential minor reduction in marine mammal impacts that might 
result; therefore, these additional mitigation measures are not 
warranted.
    Last, Appendix I (Geographic Mitigation Assessment) of the 2019 
MITT DSEIS/OEIS 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 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).
    In its application, the Navy proposed several time/area mitigations 
that were not included in the 2015-2020 MITT regulations. For most of 
the areas that were considered in the 2019 MITT DSEIS/OEIS but not 
included in this rule, the Navy found that the mitigation was not 
warranted because the anticipated reduction of adverse impacts on 
marine mammal species and their habitat was not sufficient to offset 
the impracticability of implementation. In some cases potential 
benefits to marine mammals were non-existent, while in others the 
consequences on mission effectiveness were too great. NMFS has reviewed 
the Navy's analysis in Chapter 5 Mitigation and Appendix I Geographic 
Mitigation Assessment of the 2019 MITT DSEIS/OEIS, which considers the 
same factors that NMFS considers to satisfy the least practicable 
adverse impact standard, and concurs with the analysis and conclusions. 
Therefore, NMFS is not proposing to include any of the measures that 
the Navy ruled out in the 2019 MITT DSEIS/OEIS. Below are the 
mitigation measures that NMFS determined will ensure the least 
practicable adverse impact on all affected species and their habitat, 
including the specific considerations for military readiness 
activities. The following sections summarize the mitigation measures 
that would 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 would implement 
whenever and wherever an applicable training or testing activity takes 
place within the MITT 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 33) is designed to aid Lookouts and other applicable 
Navy personnel with their observation, environmental compliance, and 
reporting responsibilities. The remainder of the procedural mitigation 
measures (Tables 34 through 50) are organized by stressor type and 
activity category and includes acoustic stressors (i.e., active sonar, 
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 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 33--Procedural Mitigation for Environmental Awareness and
                                Education
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
    All training and testing activities, as applicable
Mitigation Requirements:
    Appropriate Navy personnel (including civilian personnel) involved
     in mitigation and training or testing activity reporting under the
     specified activities will complete one or more modules of the U.S.
     Navy Afloat Environmental Compliance Training Series, as identified
     in their career path training plan. Modules include:
        --Introduction to the U.S. Navy Afloat Environmental Compliance
         Training Series. The introductory module provides information
         on environmental laws (e.g., Endangered Species Act, Marine
         Mammal Protection Act) and the corresponding responsibilities
         that are relevant to Navy training and testing activities. The
         material explains why environmental compliance is important in
         supporting the Navy's commitment to environmental stewardship.
        --Marine Species Awareness Training. All bridge watch personnel,
         Commanding Officers, Executive Officers, maritime patrol
         aircraft aircrews, anti-submarine warfare and mine warfare
         rotary-wing aircrews, Lookouts, and equivalent civilian
         personnel must successfully complete the Marine Species
         Awareness Training prior to standing watch or serving as a
         Lookout. The Marine Species Awareness Training provides
         information on sighting cues, visual observation tools and
         techniques, and sighting notification procedures. Navy
         biologists developed Marine Species Awareness Training to
         improve the effectiveness of visual observations for biological
         resources, focusing on marine mammals and sea turtles, and
         including floating vegetation, jellyfish aggregations, and
         flocks of seabirds.
        --U.S. Navy 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.

[[Page 5855]]

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

Procedural Mitigation for Acoustic Stressors
    Mitigation measures for acoustic stressors are provided in Tables 
34 and 35.
Procedural Mitigation for Active Sonar
    Procedural mitigation for active sonar is described in Table 34 
below.

            Table 34--Procedural Mitigation for Active Sonar
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Low-frequency active sonar, mid-frequency active sonar,
     high-frequency active sonar
        --For vessel-based active sonar activities, mitigation applies
         only to sources that are positively controlled and deployed
         from manned surface vessels (e.g., sonar sources towed from
         manned surface platforms).
        --For aircraft-based active sonar activities, mitigation applies
         only to sources that are positively controlled and deployed
         from manned aircraft that do not operate at high altitudes
         (e.g., rotary-wing aircraft). Mitigation does not apply to
         active sonar sources deployed from unmanned aircraft or
         aircraft operating at high altitudes (e.g., maritime patrol
         aircraft).
Number of Lookouts and Observation Platform:
     Hull-mounted sources:
        --1 Lookout: Platforms with space or manning restrictions while
         underway (at the forward part of a small boat or ship) and
         platforms using active sonar while moored or at anchor
         (including pierside).
        --2 Lookouts: Platforms without space or manning restrictions
         while underway (at the forward part of the ship).
     Sources that are not hull-mounted:
        --1 Lookout on the ship or aircraft conducting the activity.
Mitigation Requirements:
     Mitigation zones:
        --During the activity at 1,000 yd, Navy personnel must power
         down 6dB, at 500 yd, Navy personnel must power down an
         additional 4 dB (for a total of 10 dB), and at 200 yd Navy
         personnel must shut down for low-frequency active sonar >=200
         dB and hull-mounted mid-frequency active sonar.
        --200 yd shut down for low-frequency active sonar <200 dB, mid-
         frequency active sonar sources that are not hull-mounted, and
         high-frequency active sonar.
     Prior to the initial start of the activity (e.g., when
     maneuvering on station):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay the start of active
         sonar transmission.
     During the activity:
        --Low-frequency active sonar at >=200 dB or more, and hull-
         mounted mid-frequency active sonar: Navy personnel must observe
         the mitigation zone for marine mammals; power down active sonar
         transmission by 6 dB if marine mammals are observed within
         1,000 yd of the sonar source; power down an additional 4 dB
         (for a total of 10 dB total) within 500 yd; cease transmission
         within 200 yd.
        --Low-frequency active sonar <200 dB, mid-frequency active sonar
         sources that are not hull-mounted, and high-frequency active
         sonar: Navy personnel must observe the mitigation zone for
         marine mammals; cease active sonar transmission if observed
         within 200 yd of the sonar source.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         or powering up active sonar transmission) until one of the
         following 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 ship 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).
------------------------------------------------------------------------


[[Page 5856]]

Procedural Mitigation for Weapons Firing Noise
    Procedural mitigation for weapons firing noise is described in 
Table 35 below.

        Table 35--Procedural Mitigation for Weapons Firing Noise
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Weapons firing noise associated with large-caliber gunnery
     activities.
Number of Lookouts and Observation Platform:
     1 Lookout positioned on the ship conducting the firing.
     Depending on the activity, the Lookout could be the same as
     the one described in Procedural Mitigation for Explosive Medium-
     and Large-Caliber Projectiles (Table 38) or Procedural Mitigation
     for Small-, Medium-, and Large-Caliber Non-Explosive Practice
     Munitions (Table 47).
Mitigation Requirements:
     Mitigation Zone:
        --30[deg] on either side of the firing line out to 70 yd from
         the muzzle of the weapon being fired.
     Prior to the initial start of the activity:
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of weapons firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease weapons firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         weapons firing) until one of the following 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 
36 through 44.
Procedural Mitigation for Explosive Sonobuoys
    Procedural mitigation for explosive sonobuoys is described in Table 
36 below.

         Table 36--Procedural Mitigation for Explosive Sonobuoys
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive sonobuoys.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft or on a small boat.
     If additional platforms are participating in the activity,
     Navy personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for
     applicable biological resources while performing their regular
     duties.
Mitigation Requirements:
     Mitigation Zone:
        --600 yd around an explosive sonobuoy.
     Prior to the initial start of the activity (e.g., during
     deployment of a sonobuoy pattern, which typically lasts 20-30
     minutes):
        --Conduct passive acoustic monitoring for marine mammals; use
         information from detections to assist visual observations.
        --Visually observe the mitigation zone for marine mammals; if
         marine mammals are observed, relocate or delay the start of
         sonobuoy or source/receiver pair detonations.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease sonobuoy or source/receiver pair
         detonations.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         detonations) until one of the following 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.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe the vicinity of where detonations occurred; if any
         injured or dead marine mammals are observed, follow established
         incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------


[[Page 5857]]

Procedural Mitigation for Explosive Torpedoes
    Procedural mitigation for explosive torpedoes is described in Table 
37 below.

         Table 37--Procedural Mitigation for Explosive Torpedoes
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive Torpedoes.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft.
     If additional platforms are participating in the activity,
     Navy personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for
     applicable biological resources while performing their regular
     duties.
Mitigation Requirements:
     Mitigation Zone:
        --2,100 yd around the intended impact location.
     Prior to the start of the activity (e.g., during deployment
     of the target):
        --Conduct passive acoustic monitoring for marine mammals; use
         information from detections to assist visual observations.
        --Visually observe the mitigation zone for marine mammals; if
         marine mammals are observed, relocate or delay the start of
         firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following conditions has been met: (1)
         The animal is observed exiting the mitigation zone; (2) the
         animal is thought to have exited the mitigation zone based on a
         determination of its course, speed, and movement relative to
         the intended impact location; or (3) the mitigation zone has
         been clear from any additional sightings for 10 min when the
         activity involves aircraft that have fuel constraints, or 30
         min when the activity involves aircraft that are not typically
         fuel constrained.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe the vicinity of where detonations occurred; if any
         injured or dead marine mammals are observed, follow established
         incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Medium- and Large-Caliber Projectiles
    Procedural mitigation for medium- and large-caliber projectiles is 
described in Table 38 below.

 Table 38--Procedural Mitigation for Explosive Medium-Caliber and Large-
                           Caliber Projectiles
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Gunnery activities using explosive medium-caliber and large-
     caliber projectiles.
        --Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
     1 Lookout on the vessel or aircraft conducting the
     activity.
        --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 (Table 35).
     If additional platforms are participating in the activity,
     Navy personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for
     applicable biological resources while performing their regular
     duties.
Mitigation Requirements:
     Mitigation zones:
        --200 yd around the intended impact location for air-to-surface
         activities using explosive medium-caliber projectiles.
        --600 yd around the intended impact location for surface-to-
         surface activities using explosive medium-caliber projectiles.
        --1,000 yd around the intended impact location for surface-to-
         surface activities using explosive large-caliber projectiles.
     Prior to the initial start of the activity (e.g., when
     maneuvering on station):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay the start of firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:

[[Page 5858]]

 
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following 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.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe the vicinity of where detonations occurred; if any
         injured or dead marine mammals are observed, follow established
         incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Missiles and Rockets
    Procedural mitigation for explosive missiles and rockets is 
described in Table 39 below.

   Table 39--Procedural Mitigation for Explosive Missiles and Rockets
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Aircraft-deployed explosive missiles and rockets.
        --Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft.
     If additional platforms are participating in the activity,
     Navy personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for
     applicable biological resources while performing their regular
     duties.
Mitigation Requirements:
     Mitigation zones:
        --900 yd around the intended impact location for missiles or
         rockets with 0.6-20 lb net explosive weight.
        --2,000 yd around the intended impact location for missiles with
         21-500 lb net explosive weight.
     Prior to the initial start of the activity (e.g., during a
     fly-over of the mitigation zone):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay the start of firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following conditions has been met: (1)
         The animal is observed exiting the mitigation zone; (2) the
         animal is thought to have exited the mitigation zone based on a
         determination of its course, speed, and movement relative to
         the intended impact location; or (3) the mitigation zone has
         been clear from any additional sightings for 10 min when the
         activity involves aircraft that have fuel constraints, or 30
         min when the activity involves aircraft that are not typically
         fuel constrained.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe the vicinity of where detonations occurred; if any
         injured or dead marine mammals are observed, follow established
         incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Bombs
    Procedural mitigation for explosive bombs is described in Table 40 
below.

           Table 40--Procedural Mitigation for Explosive Bombs
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive bombs.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in the aircraft conducting the
     activity.

[[Page 5859]]

 
     If additional platforms are participating in the activity,
     Navy personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for
     applicable biological resources while performing their regular
     duties.
Mitigation Requirements:
     Mitigation zone:
        --2,500 yd around the intended target.
     Prior to the initial start of the activity (e.g., when
     arriving on station):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay the start of bomb
         deployment.
     During the activity (e.g., during target approach):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease bomb deployment.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         bomb deployment) until one of the following 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.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe the vicinity of where detonations occurred; if any
         injured or dead marine mammals are observed, follow established
         incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Sinking Exercises
    Procedural mitigation for sinking exercises is described in Table 
41 below.

          Table 41--Procedural Mitigation for Sinking Exercises
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Sinking exercises.
Number of Lookouts and Observation Platform:
     2 Lookouts (one positioned in an aircraft and one on a
     vessel).
     If additional platforms are participating in the activity,
     Navy personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for
     applicable biological resources while performing their regular
     duties.
Mitigation Requirements:
     Mitigation Zone:
        --2.5 NM around the target ship hulk.
     Prior to the initial start of the activity (90 min. prior
     to the first firing):
        --Conduct aerial observations of the mitigation zone for marine
         mammals; if marine mammals are observed, delay the start of
         firing.
     During the activity:
        --Conduct passive acoustic monitoring for marine mammals; use
         information from detections to assist visual observations.
        --Visually observe the mitigation zone for marine mammals from
         the vessel; if marine mammals are observed, Navy personnel must
         cease firing.
        --Immediately after any planned or unplanned breaks in weapons
         firing of longer than 2 hours, observe the mitigation zone for
         marine mammals from the aircraft and vessel; if marine mammals
         are observed, Navy personnel must delay recommencement of
         firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following 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.
     After completion of the activity (for 2 hours after sinking
     the vessel or until sunset, whichever comes first):
        --Observe the vicinity of where detonations occurred; if any
         injured or dead marine mammals are observed, Navy personnel
         must follow established incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------


[[Page 5860]]

Procedural Mitigation for Explosive Mine Countermeasure and 
Neutralization Activities
    Procedural mitigation for explosive mine countermeasure and 
neutralization activities is described in Table 42 below.

  Table 42--Procedural Mitigation for Explosive Mine Countermeasure and
                        Neutralization Activities
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive mine countermeasure and neutralization
     activities.
Number of Lookouts and Observation Platform:
     1 Lookout positioned on a vessel or in an aircraft.
     If additional platforms are participating in the activity,
     Navy personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for
     applicable biological resources while performing their regular
     duties.
Mitigation Requirements:
     Mitigation Zone:
        --600 yd around the detonation site.
     Prior to the initial 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 the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay the start of
         detonations.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease detonations.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         detonations) until one of the following 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 that have fuel constraints, or 30
         min. when the activity involves aircraft that are not typically
         fuel constrained.
     After completion of the activity (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 the vicinity of where detonations occurred; if any
         injured or dead marine mammals are observed, follow established
         incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Mine Neutralization Activities 
Involving Navy Divers
    Procedural mitigation for explosive mine neutralization activities 
involving Navy divers is described in Table 43 below.

    Table 43--Procedural Mitigation for Explosive Mine Neutralization
                    Activities Involving Navy Divers
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive mine neutralization activities involving Navy
     divers.
Number of Lookouts and Observation Platforms:
     2 Lookouts (two small boats with one Lookout each, or one
     Lookout on a small boat and one in a rotary-wing aircraft) when
     implementing the smaller mitigation zone.
     4 Lookouts (two small boats with two Lookouts each), and a
     pilot or member of an aircrew will serve as an additional Lookout
     if aircraft are used during the activity, when implementing the
     larger mitigation zone.
     All divers placing the charges on mines will support the
     Lookouts while performing their regular duties and will report
     applicable sightings to their supporting small boat or Range Safety
     Officer.
     If additional platforms are participating in the activity,
     Navy personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for
     applicable biological resources while performing their regular
     duties.
Mitigation Requirements:
     Mitigation Zones:
        --500 yd around the detonation site during activities under
         positive control.
        --1,000 yd around the detonation site during activities using
         time-delay fuses.
     Prior to the initial 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 the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay the start of
         detonations or fuse initiation.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease detonations or fuse initiation.

[[Page 5861]]

 
        --To the maximum extent practical depending on mission
         requirements, safety, and environmental conditions, boats will
         position themselves near the mid-point of the mitigation zone
         radius (but outside of the detonation plume and human safety
         zone), will position themselves on opposite sides of the
         detonation location (when two boats are used), and will travel
         in a circular pattern around the detonation location with one
         Lookout observing inward toward the detonation site and the
         other observing outward toward the perimeter of the mitigation
         zone.
        --If used, aircraft will travel in a circular pattern around the
         detonation location to the maximum extent practicable.
        --The Navy will not set time-delay firing devices to exceed 10
         min.
     Commencement/recommencement conditions after a marine
     mammal before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         detonations) until one of the following 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 during
         activities under positive control with aircraft that have fuel
         constraints, or 30 min during activities under positive control
         with aircraft that are not typically fuel constrained and
         during activities using time-delay firing devices.
     After completion of an activity (for 30 min):
        --Observe the vicinity of where detonations occurred; if any
         injured or dead marine mammals are observed, follow established
         incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Maritime Security Operations--Anti-Swimmer 
Grenades
    Procedural mitigation for maritime security operations--anti-
swimmer grenades is described in Table 44 below.

 Table 44--Procedural Mitigation for Maritime Security Operations--Anti-
                            Swimmer Grenades
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Maritime Security Operations--Anti-Swimmer Grenades.
Number of Lookouts and Observation Platform:
     1 Lookout positioned on the small boat conducting the
     activity.
     If additional platforms are participating in the activity,
     Navy personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for
     applicable biological resources while performing their regular
     duties.
Mitigation Requirements:
     Mitigation zone:
        --200 yd around the intended detonation location.
     Prior to the initial start of the activity (e.g., when
     maneuvering on station):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay the start of
         detonations.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease detonations.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         detonations) until one of the following 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.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe vicinity of where detonations occurred; if any injured
         or dead marine mammals are observed, follow established
         incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Physical Disturbance and Strike Stressors
    Mitigation measures for physical disturbance and strike stressors 
are provided in Table 45 through Table 49.
Procedural Mitigation for Vessel Movement
    Procedural mitigation for vessel movement is described in Table 45 
below.

[[Page 5862]]



           Table 45--Procedural Mitigation for Vessel Movement
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Vessel movement:
        --The mitigation will not be applied if (1) the vessel's safety
         is threatened, (2) the vessel is restricted in its ability to
         maneuver (e.g., during launching and recovery of aircraft or
         landing craft, during towing activities, when mooring, etc.),
         (3) the vessel is operated autonomously, or (4) when
         impractical based on mission requirements (e.g., during
         Amphibious Assault and Amphibious Raid exercises).
Number of Lookouts and Observation Platform:
     1 Lookout on the vessel that is underway.
Mitigation Requirements:
     Mitigation Zones:
        --500 yd around whales.
        --200 yd around other marine mammals (except bow-riding
         dolphins).
     During the activity:
        --When underway, observe the mitigation zone for marine mammals;
         if marine mammals are observed, maneuver to maintain distance.
     Additional requirements:
        --If a marine mammal vessel strike occurs, the Navy will follow
         the established incident reporting procedures.
------------------------------------------------------------------------

Procedural Mitigation for Towed In-Water Devices
    Procedural mitigation for towed in-water devices is described in 
Table 46 below.

       Table 46--Procedural Mitigation for Towed In-Water Devices
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Towed in-water devices:
        --Mitigation applies to devices that are towed from a manned
         surface platform or manned aircraft.
        --The mitigation will not be applied if the safety of the towing
         platform or in-water device is threatened.
Number of Lookouts and Observation Platform:
     1 Lookout positioned on a manned towing platform.
Mitigation Requirements:
     Mitigation Zones:
        --250 yd. around marine mammals.
     During the activity (i.e., when towing an in-water device):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are 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 47 below.

 Table 47--Procedural Mitigation for Small-, Medium-, and Large-Caliber
                    Non-Explosive Practice Munitions
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Gunnery activities using small-, medium-, and large-caliber
     non-explosive practice munitions
        --Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
     1 Lookout positioned on the platform conducting the
     activity.
     Depending on the activity, the Lookout could be the same as
     the one described in Procedural Mitigation for Weapons Firing Noise
     (Table 35).
Mitigation Requirements:
     Mitigation Zone:
        --200 yd around the intended impact location.
         Prior to the initial start of the activity (e.g., when
         maneuvering on station):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay the start of firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:

[[Page 5863]]

 
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following 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 48 below.

 Table 48--Procedural Mitigation for Non-Explosive Missiles and Rockets
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Aircraft-deployed non-explosive missiles and rockets.
     Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft.
Mitigation Requirements:
     Mitigation Zone:
        --900 yd. around the intended impact location.
     Prior to the initial start of the activity (e.g., during a
     fly-over of the mitigation zone):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay the start of firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting prior to or during the activity:
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following 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 49 below.

 Table 49--Procedural Mitigation for Non-Explosive Bombs and Mine Shapes
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Non-explosive bombs.
     Non-explosive mine shapes during mine laying activities.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft.
 Mitigation Requirements:
     Mitigation Zone:
        --1,000 yd around the intended target.
     Prior to the start of the activity (e.g., when arriving on
     station):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, relocate or delay start of bomb
         deployment or mine laying.
     During the activity (e.g., during approach of the target or
     intended minefield location):
        --Observe the mitigation zone for marine mammals; if marine
         mammals are observed, cease bomb deployment or mine laying.
     Commencement/recommencement conditions after a marine
     mammal sighting prior to or during the activity:

[[Page 5864]]

 
        --Navy personnel will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         bomb deployment or mine laying) until one of the following
         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 would implement 
mitigation measures within mitigation areas to avoid or minimize 
potential impacts on marine mammals. 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 I 
(Geographic Mitigation Assessment) of the 2019 MITT DSEIS/OEIS. The 
Navy took into account public comments received on the 2019 MITT DSEIS/
OEIS, best available science, and the practicability of implementing 
additional mitigation measures and has enhanced its mitigation areas 
and mitigation measures, beyond the 2015-2020 regulations, to further 
reduce impacts to marine mammals.
    NMFS also worked with the Navy after it submitted its 2019 
rulemaking/LOA application but prior to the development of this 
proposed rule and the Navy also agreed to expand the geographic 
mitigation areas for Marpi Reef and Chalan Kanoa Reef Geographic 
Mitigation Areas to more fully encompass the 400 m isobaths based on 
the available data indicating the presence of humpback whale mother/
calf pairs (seasonal breeding area), which is expected to further avoid 
impacts from explosives that would be more likely to affect 
reproduction or survival of individuals and could adversely impact the 
species. The Navy also agreed to the addition of the Marpi Reef and 
Chalan Kanoa Reef Awareness Notification Message Areas, which allow 
Navy personnel to inform other personnel of the presence of humpback 
whales, enabling them to avoid potential impacts from vessel strikes 
and training and testing activities as these areas contain important 
seasonal breeding habitat for this species.
    Information on the mitigation measures that the Navy will implement 
within geographic mitigation areas is provided in Table 50 (see below). 
The mitigation applies year-round unless specified otherwise in the 
table.
    NMFS conducted an independent analysis of the mitigation areas that 
the Navy proposed, which are described below. NMFS preliminarily 
concurs with the Navy's analysis, which indicates that the measures in 
these mitigation areas are both practicable and will reduce the 
likelihood or severity of adverse impacts to marine mammal species or 
their habitat in the manner described in the Navy's analysis and this 
rule. NMFS is heavily reliant on the Navy's description of operational 
practicability, since the Navy is best equipped to describe the degree 
to which a given mitigation measure affects personnel safety or mission 
effectiveness, and is practical to implement. The Navy considers the 
measures in this proposed rule to be practicable, and NMFS concurs. We 
further discuss the manner in which the Geographic Mitigation Areas in 
the proposed rule will reduce the likelihood or severity of adverse 
impacts to marine mammal species or their habitat in the Preliminary 
Analysis and Negligible Impact Determination section. Marpi Reef and 
Chalan Kanoa Reef Geographic Mitigation Areas (Both seasonal and year 
round):
    The Navy would not use in-water explosives year-round. The Navy 
would also report the total hours of MF1 surface ship hull-mounted mid-
frequency active sonar from December through April used in this area in 
its annual training and testing activity reports submitted to NMFS 
(Table 50).
    Marpi Reef and Chalan Kanoa Reef Awareness Notification Message 
Areas (December-April):
    The Navy would issue an annual seasonal awareness notification 
message to alert ships and aircraft operating in the area to the 
possible presence of large whales or increased concentrations of 
humpback whales between December and April. To maintain safety of 
navigation and to avoid interactions with large whales during transits, 
the Navy would instruct vessels to remain vigilant to the presence of 
large whales, that when concentrated seasonally, may become vulnerable 
to vessel strikes. Platforms would 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 (Table 50).
    Agat Bay Nearshore Geographic Mitigation Area:
    The Navy would not use in-water explosives year-round. The Navy 
also would not use MF1 ship hull-mounted mid-frequency active sonar 
year round (Table 50).

  Table 50--Geographic Mitigation Areas for Marine Mammals in the MITT
                               Study Area
------------------------------------------------------------------------
                 Geographic Mitigation Area Description
-------------------------------------------------------------------------
Stressor or Activity:
     MF1 Sonar.
     Explosives.
 
Mitigation Area Requirements:
     Marpi Reef:
        --Seasonal (December-April): The Navy will report the total
         hours of MF1 surface ship hull-mounted mid-frequency active
         sonar used in this area in its annual training and testing
         activity reports submitted to NMFS.

[[Page 5865]]

 
        --Year-round: Year-round prohibition on in-water explosives.
         Should national security present a requirement to use
         explosives that could potentially result in the take of marine
         mammals 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
         (e.g., explosives usage) in its annual activity reports
         submitted to NMFS.
     Chalan Kanoa Reef:
        --Seasonal (December-April): The Navy will report the total
         hours of MF1 surface ship hull-mounted mid-frequency active
         sonar used in this area in its annual training and testing
         activity reports submitted to NMFS.
        --Year-round: Year-round prohibition on in-water explosives.
         Should national security present a requirement to use
         explosives that could potentially result in the take of marine
         mammals 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
         (e.g., explosives usage) in its annual activity reports
         submitted to NMFS.
     Marpi Reef and Chalan Kanoa Reef Awareness Notification
     Message Areas:
        --Seasonal (December-April): The Navy will issue an annual
         seasonal awareness notification message to alert ships and
         aircraft operating in the area to the possible presence of
         large whales or increased concentrations of humpback whales
         between December and April. 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 whales, that when concentrated seasonally,
         may become vulnerable to vessel strikes. Platforms 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.
     Agat Bay Nearshore:
        --Year-round prohibition on use of MF1 ship hull-mounted mid-
         frequency active sonar and in-water explosives. Should national
         security present a requirement to use surface ship hull-mounted
         active sonar or explosives that could potentially result in the
         take of marine mammals 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 (e.g., sonar hours or explosives usage) in its
         annual activity reports submitted to NMFS.
------------------------------------------------------------------------

    Humpback whales have been sighted in the MITT Study Area from 
January through March (U.S. Department of the Navy, 2005b; Uyeyama, 
2014), and male humpback songs have been recorded from December through 
April (Hill et al., 2017a; Klinck et al., 2016; Munger et al., 2014; 
Norris et al., 2014; Oleson et al., 2015). Recent scientific research 
by NOAA Fisheries Pacific Island Fisheries Science Center (PIFSC) 
indicates the shallower water around Marpi Reef and Chalan Kanoa Reef 
are important habitat for humpback whale breeding and calving. With the 
presence of humpback whale newborn calves and competitive groups, 
researchers were able to confirm this new breeding location (NOAA, 
2018). The Navy obtained all humpback whale sighting data in the 
Marianas from the PIFSC (2015-2019) to determine the extent of this 
geographic mitigation area. Humpback whales, including mother-calf 
pairs, have been seasonally present in the Marpi Reef Area in shallow 
waters (out to the 400 m isobaths) and the area may be of biological 
importance to humpback whales for biologically important life processes 
associated with reproduction (e.g., breeding, birthing, and nursing) 
for part of the year.
    Calves are considered more sensitive and susceptible to adverse 
impacts from Navy stressors than adults (especially given their lesser 
weight and the association between weight and explosive impacts), as 
well as being especially reliant upon mother-calf communication for 
protection and guidance. Both gestation and lactation increase energy 
demands for mothers. Breeding activities typically involve 
vocalizations and complex social interactions that can include violent 
interactions between males. Reducing exposure of humpback whales to 
explosive detonations in this area and time is expected to reduce the 
likelihood of impacts that could affect reproduction or survival, by 
minimizing impacts on calves during this sensitive life stage, avoiding 
the additional energetic costs to mothers of avoiding the area during 
explosive exercises, and minimizing the chances that important breeding 
behaviors are interrupted to the point that reproduction is inhibited 
or abandoned for the year, or otherwise interfered with. Since the Navy 
submitted its application, it has extended both the Marpi Reef and 
Chalan Kanoa Reef Mitigation Areas out to the 400 m isobath to account 
for animals transiting to and from the more critical < 200 m areas used 
by humpback whales for breeding behaviors (Figures 2 and 3 below). 
Additional data would be needed to determine which DPS the humpbacks 
are assigned to.
BILLING CODE 3510-22-P

[[Page 5866]]

[GRAPHIC] [TIFF OMITTED] TP31JA20.008


[[Page 5867]]


[GRAPHIC] [TIFF OMITTED] TP31JA20.009

    Agat Bay Nearshore Geographic Mitigation Area (year-round):
    The Navy would not use MF1 ship hull-mounted mid-frequency active 
sonar and in-water explosives year-round in the Agat Bay Nearshore 
Geographic Mitigation Area (Table 50 above). Spinner dolphins are known 
to

[[Page 5868]]

congregate and rest in Agat Bay. Behavioral disruptions during resting 
periods can adversely impact health and energetic budgets by not 
allowing animals to get the needed rest and/or by creating the need to 
travel and expend additional energy to find other suitable resting 
areas. Avoiding sonar and explosives in this area reduces the 
likelihood of impacts that would affect reproduction and survival.
    The boundaries of the proposed Agat Bay Nearshore Geographic 
Mitigation Area were defined by Navy scientists based on spinner 
dolphin sightings documented during small boat surveys from 2010 
through 2014. Spinner dolphins have been the most frequently 
encountered species during small boat reconnaissance surveys conducted 
in the Mariana Islands since 2010. Consistent with more intensive 
studies completed for the species in the Hawaiian Islands, island-
associated spinner dolphins are expected to occur in shallow water 
resting areas (about 50 meters (m) deep or less) in the morning and 
throughout the middle of the day, moving into deep waters offshore 
during the night to feed (Heenehan et al., 2016b; Heenehan et al., 
2017a; Hill et al., 2010; Norris & Dohl, 1980).
    The Agat Bay Nearshore Geographic Mitigation Area encompasses the 
shoreline between Tipalao, Dadi Beach, and Agat on the west coast of 
Guam, with a boundary across the bay enclosing an area of approximately 
5 km\2\ in relatively shallow waters (less than 100 m) (Figure 4).

[[Page 5869]]

[GRAPHIC] [TIFF OMITTED] TP31JA20.010

BILLING CODE 3510-22-C
    Marpi Reef and Chalan Kanoa Reef Awareness Notification Message 
Areas (Seasonal):
    The Navy would issue an annual seasonal awareness notification 
message to alert ships and aircraft operating in the area to the 
possible presence of large whales including increased concentrations of 
humpback whales between December and April. To maintain safety of 
navigation and to avoid interactions with large whales during transits, 
the Navy would instruct vessels to remain vigilant to the presence of 
large whales, that when concentrated seasonally, may become more 
vulnerable to vessel strikes. Platforms would use the information from 
the awareness notification messages to assist their visual observation 
of applicable mitigation

[[Page 5870]]

zones during training and testing activities and to aid in the 
implementation of procedural mitigation. This restriction would further 
reduce any potential for vessel strike of humpback whales when they may 
be seasonally concentrated.

Mitigation Conclusions

    NMFS has carefully evaluated the Navy's proposed mitigation 
measures--many of which were developed with NMFS' 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 2019 MITT DSEIS/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 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 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 these proposed mitigation measures are appropriate 
means of effecting the least practicable adverse impact on marine 
mammal species and their habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and 
considering specifically personnel safety, practicality of 
implementation, and impact on the effectiveness of the military 
readiness activity. Additionally, an adaptive management component 
helps further ensure that mitigation is regularly assessed and provides 
a mechanism 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 Navy's 
activities and 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 and their habitat, NMFS will consider all public comments to 
help inform our final determination. Consequently, the proposed 
mitigation measures may be refined, modified, removed, or added to 
prior to the issuance of the final rule based on public comments 
received and, as appropriate, analysis of additional potential 
mitigation measures.

Proposed Monitoring

    Section 101(a)(5)(A) of the MMPA states that in order to authorize 
incidental take 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 incidental take authorizations must include the suggested 
means of accomplishing the necessary monitoring and reporting that will 
result in increased knowledge of the species and of the level of taking 
or impacts on populations of marine mammals that are expected to be 
present.
    Although the Navy has been conducting research and monitoring in 
the MITT Study Area for over 20 years, it developed a formal marine 
species monitoring program in support of the MMPA and ESA 
authorizations in 2009. This robust program has resulted in hundreds of 
technical reports and publications on marine mammals that have informed 
Navy and NMFS analyses 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) (https://seamap.env.duke.edu/).
    The Navy will continue collecting monitoring data to inform our 
understanding of the occurrence of marine mammals in the MITT Study 
Area; the likely exposure of marine mammals to stressors of concern in 
the MITT Study 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 seeks to leverage and build on 
existing research efforts whenever possible.
    As agreed upon between the Navy and NMFS, the 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 activities.

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:
    [ssquf] An increase in our 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);

[[Page 5871]]

    [ssquf] An increase in our 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);
    [ssquf] An increase in our 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);
    [ssquf] An increase in our 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);
    [ssquf] An increase in our understanding of the effectiveness of 
mitigation and monitoring measures;
    [ssquf] A better understanding and record of the manner in which 
the Navy complies with the incidental take regulations and LOAs and the 
ESA Incidental Take Statement;
    [ssquf] 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
    [ssquf] Ensuring that adverse impact of activities remains at the 
least practicable level.

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 intermediate scientific objectives and a 
conceptual framework incorporating a progression of knowledge spanning 
occurrence, exposure, response, and consequence. The Strategic Planning 
Process for Marine Species Monitoring is used to set overarching 
intermediate 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 
would leverage multiple techniques for data acquisition and analysis 
whenever possible. The Strategic Planning Process for Marine Species 
Monitoring is also available online (https://www.navymarinespeciesmonitoring.us/).

Past and Current Monitoring in the MITT Study Area

    The monitoring program has undergone significant changes since the 
first rule was issued for the MITT Study Area in 2009, which highlights 
the monitoring program's 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.
    Progress has also been made on the conceptual framework categories 
from the Scientific Advisory Group for Navy Marine Species Monitoring 
(U.S. Department of the Navy, 2011c), ranging from occurrence of 
animals, to their exposure, response, and population consequences. The 
Navy continues to manage the Atlantic and Pacific program as a whole, 
with monitoring in each range complex taking a slightly different but 
complementary approach. The Navy has continued to use the approach of 
layering multiple simultaneous components in many of the range 
complexes to leverage an increase in return of the progress toward 
answering scientific monitoring questions. This includes, in the 
Marianas for example, (a) glider deployment in offshore areas, (b) 
analysis of existing passive acoustic monitoring datasets, (c) small 
boat surveys using visual, biopsy and satellite tagging and (d) 
seasonal, humpback whale specific surveys.
    Specific monitoring under the current regulations includes:
    [ssquf] Review of the available data and analyses in the MITT Study 
Area 2010 through February 2018 (2019a).
    [ssquf] The continuation of annual small vessel nearshore surveys, 
sightings, satellite tagging, biopsy and genetic analysis, photo-
identification, and opportunistic acoustic recording off Guam, Saipan, 
Tinian, Rota, and Aguigan in partnership with NMFS (Hill et al., 2015; 
Hill et al., 2016b; Hill et al., 2017a; Hill et al., 2018, Hill et al., 
2019b). The satellite tagging and genetic analyses have resulted in the 
first information discovered on the movement patterns, habitat 
preference, and population structure of multiple odontocete species in 
the MITT Study Area.
    [ssquf] Since 2015, the addition of a series of small vessel 
surveys in the winter season dedicated to humpback whales has provided 
new information relating to the occurrence, calving behavior, and 
population identity of this species (Hill et al., 2016a; Hill et al., 
2017b), which had not previously been sighted during the previous small 
vessel surveys in the summer or winter. This work has included sighting 
data, photo ID matches of individuals to other areas demonstrating 
migration as well as re-sights within the Marianas across different 
years, and the collection of biopsy samples for genetic analyses of 
populations.
    [ssquf] The continued deployment of passive acoustic monitoring 
devices and analysis of acoustic data obtained using bottom-moored 
acoustic recording devices deployed by NMFS has provided information on 
the presence and seasonal occurrence of mysticetes, as well as the 
occurrence of cryptic odontocetes typically found offshore, including 
beaked whales and Kogia spp. (Hill et al., 2015; Hill et al., 2016a; 
Hill et al., 2016b; Hill et al., 2017a; Munger et al., 2015; Norris et 
al., 2017; Oleson et al., 2015; Yack et al., 2016).
    [ssquf] Acoustic surveys using autonomous gliders were used to 
characterize the occurrence of odontocetes and mysticetes in abyssal 
offshore waters near Guam and CNMI, including species not seen in the 
small vessel visual survey series such as killer whales and Risso's 
dolphins. Analysis of collected

[[Page 5872]]

data also provided new information on the seasonality of baleen whales, 
patterns of beaked whale occurrence and potential call variability, and 
identification of a new unknown marine mammal call (Klinck et al., 
2016b; Nieukirk et al., 2016).
    [ssquf] Visual surveys were conducted from a shore-station at high 
elevation on the north shore of Guam to document the nearshore 
occurrence of marine mammals in waters where small vessel visual 
surveys are challenging due to regularly high sea states (Deakos and 
Richlen, 2015; Deakos et al., 2016).
    [ssquf] Analysis of archive data that included marine mammal 
sightings during Guam Department of Agriculture Division of Aquatic and 
Wildlife Resources aerial surveys undertaken between 1963 and 2012 
(Martin et al., 2016).
    [ssquf] Analysis of archived acoustic towed-array data for an 
assessment of the abundance and density of minke whales (Norris et al., 
2017), abundance and density of sperm whales (Yack et al., 2016), and 
the characterization of sei and humpback whale vocalizations (Norris et 
al., 2014).
    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 the Office of Naval Research programs have also resulted 
in significant contributions to information on hearing ranges and 
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 the 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, and marine 
mammals observed within the mitigation zones when mitigations are 
implemented. These data are provided to NMFS in both classified and 
unclassified annual exercise reports, which would continue under this 
proposed rule.
    NMFS has received multiple years' worth of annual exercise and 
monitoring reports addressing active sonar use and explosive 
detonations within the MITT 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 
training and testing activities within the MITT Study Area. The Navy's 
annual exercise and monitoring reports may be viewed at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities and https://www.navymarinespeciesmonitoring.us.
    Prior to Phase I monitoring, the information on marine mammal 
presence and occurrence in the MIRC was largely absent and limited to 
anecdotal information from incidental sightings and stranding events 
(U.S. Department of the Navy, 2005). In 2007, the Navy funded the 
Mariana Islands Sea Turtle and Cetacean Survey (MISTCS) (U.S. 
Department of the Navy, 2007) to proactively support the baseline data 
feeding the MIRC EIS (U.S. Department of the Navy, 2010b). The MISTCS 
research effort was the first systematic marine survey in these waters. 
This survey provided the first empirically-based density estimates for 
marine mammals (Fulling et al., 2011). In cooperation with NMFS, the 
Phase I monitoring program beginning in 2010 was designed to address 
basic occurrence-level questions in the MIRC, whereas monitoring the 
impacts of Navy training such as exposure to mid-frequency active sonar 
was planned for other Navy range complexes where marine mammal 
occurrence was already better characterized.
    This emphasis on studying occurrence continued through Phase I and 
II monitoring in the MIRC, and combined various complementary 
methodologies. Small vessel visual surveys collected occurrence 
information, and began building the first individual identification 
catalog for multiple species (Hill et al., 2014). During these visual 
surveys, biopsies were collected for genetic analysis and satellite 
tags were also applied, resulting in a progressively improving picture 
of the habitat use and population structure of various species. Deep 
water passive acoustic deployments, including autonomous gliders with 
passive acoustic recorders, added complementary information on species 
groups such as baleen whales and beaked whales that were rarely sighted 
on the vessel surveys (Klinck et al., 2015; Munger et al., 2014; Munger 
et al., 2015; Nieukirk et al., 2016; Norris et al., 2015). Other 
methodologies were also explored to fill other gaps in waters generally 
inaccessible to the small boat surveys including a shore-station to 
survey waters on the windward side of Guam (Deakos et al., 2016). When 
available, platforms of opportunity on large vessels were utilized for 
visual survey and tagging (Oleson and Hill, 2010b).
    At the close of Phase II monitoring, establishing the fundamentals 
of marine mammal occurrence in the MITT Study Area has now been largely 
completed. The various visual and acoustic platforms have encountered 
nearly all of the species that are expected to occur in the MITT Study 
Area. The photographic catalogs have progressively grown to the point 
that abundance analyses may be attempted for the most commonly-
encountered species. Beyond occurrence, questions related to exposure 
to Navy training have been addressed, such as utilizing satellite tag 
telemetry to evaluate overlap of habitat use with underwater detonation 
training sites. Also during Phase II monitoring, a pilot study to 
investigate reports of humpback whales occasionally occurring off 
Saipan has proven fruitful, yielding confirmation of this species 
there, photographic matches of individuals to other waters in the 
Pacific Ocean, as well as genetics data that provide clues as to the 
population identity of these animals (Hill et al., 2016a; Hill et al., 
2017b). Importantly, the compiled data were also used to inform 
proposals for new mitigation areas for this proposed rule and 
associated consultations.
    The ongoing regional species-specific study questions and results 
from recent efforts are publicly available on the Navy's Monitoring 
Program website. With basic occurrence information now well-
established, the primary goal of monitoring in the MITT Study Area

[[Page 5873]]

under this proposed rule would be to close out these studies with final 
analyses. As the collection and analysis of basic occurrence data 
across Navy ranges (including MITT) is completed, the focus of 
monitoring across all Navy range complexes will progressively move 
toward addressing the important questions of exposure and response to 
mid-frequency active sonar and other Navy training, as well as the 
consequences of those exposures, where appropriate. The Navy's 
hydrophone-instrumented ranges have proven to be a powerful tool 
towards this end and because of the lack of such an instrumented range 
in the MITT Study Area, monitoring investments are expected to begin 
shifting to other Navy range complexes as the currently ongoing 
research efforts in the Mariana Islands are completed. Any future 
monitoring results for the MITT Study Area will continue to be 
published on the Navy's Monitoring Program website, as well as 
discussed during annual adaptive management meetings between NMFS and 
the Navy.
    The Navy's marine species monitoring program typically supports 
several monitoring projects in the MITT Study Area at any given time. 
Additional details on the scientific objectives for each project can be 
found at https://www.navymarinespeciesmonitoring.us/regions/pacific/current-projects/. Projects can be either major multi-year efforts, or 
one to two-year special studies. The Navy's proposed monitoring 
projects going into 2020 include:
    [ssquf] Significant funding to NMFS' Pacific Island Fisheries 
Science Center (PIFSC) for spring-summer 2021 large vessel visual and 
acoustic survey through the Mariana Islands;
    [ssquf] Humpback whale visual survey at FDM;
    [ssquf] Continued coordination with NMFS PIFSC for small boat 
humpback whale surveys at other Mariana Islands (e.g., Saipan);
    [ssquf] Analysis of previously deployed passive acoustic sensors 
for detection of humpback whale vocalizations at other islands (e.g.. 
Pagan);
    [ssquf] Funding to support long-term (weeks-months) satellite tag 
tracking of humpback whales (field work likely in winter 2021); and
    [ssquf] Funding to researchers with PIFSC for detailed necropsy 
support for select stranded marine mammals in Hawaii and the Mariana 
Islands.

Adaptive Management

    The proposed regulations governing the take of marine mammals 
incidental to Navy training and testing activities in the MITT Study 
Area 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 seven-year regulations.
    The reporting requirements associated with this 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. 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 more effectively accomplishing the goals of 
the mitigation and monitoring and if the measures are practicable. If 
the modifications to the mitigation, monitoring, or reporting measures 
are substantial, NMFS would publish a notice of the planned LOA in the 
Federal Register and solicit public comment.
    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. The 
results from monitoring reports and other studies may be viewed at 
https://www.navymarinespeciesmonitoring.us.

Proposed Reporting

    In order to issue 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. Reports 
from individual monitoring events, results of analyses, publications, 
and periodic progress reports for specific monitoring projects will be 
posted to the Navy's Marine Species Monitoring web portal: https://www.navymarinespeciesmonitoring.us.
    Currently, there are several different reporting requirements 
pursuant to the regulations. All of these reporting requirements would 
be continued under this proposed rule for the seven-year period.

Notification of Injured, Live Stranded or Dead Marine Mammals

    The Navy would consult 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 is available for review at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.

Annual MITT Monitoring Report

    The Navy would submit an annual report to NMFS of the MITT 
monitoring describing the implementation and results from the previous 
calendar year. Data collection methods would be standardized across 
Pacific Range Complexes including the MITT, HSTT, NWTT, and GOA Study 
Areas to allow for comparison in different geographic locations. The 
draft of the annual monitoring report would be submitted either three 
months after the end of 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 MITT 
Study Area associated with the Integrated Comprehensive Monitoring 
Program. Similar study questions would be treated together so that 
summaries can be provided for each topic area. The report need not 
include analyses and content that do not provide direct assessment of 
cumulative progress on the monitoring plan study questions. NMFS would 
submit comments on the draft monitoring report, if any, within three 
months of receipt. The report would be considered final after the Navy 
has addressed NMFS' comments, or three months after the submittal of 
the draft if NMFS does not have comments.
    As an alternative, the Navy may submit a Pacific-Range Complex 
annual Monitoring Plan report to fulfill this requirement. Such a 
report describes progress of knowledge made with respect to monitoring 
study questions across multiple Navy ranges associated

[[Page 5874]]

with the ICMP. Similar study questions would be treated together so 
that progress on each topic is 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 would 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.

Annual MITT Training Exercise Report and Testing Activity Reports

    Each year, the Navy would submit one preliminary report (Quick Look 
Report) 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 would also a submit detailed report (MITT Annual 
Training Exercise Report and Testing Activity Report) to NMFS within 
three months after the one-year anniversary of the date of issuance of 
the LOA. The annual report would 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 annual report will also 
contain cumulative sonar and explosive use quantity from previous 
years' reports through the current year. Additionally, if there were 
any changes to the sound source allowance in the reporting year, or 
cumulatively, the report would include a discussion of why the change 
was made and include analysis to support how the change did or did not 
affect the analysis in the MITT EIS/OEIS and MMPA final rule. The 
annual report would also include the details regarding specific 
requirements associated with specific mitigation areas. The analysis in 
the detailed report would be based on the accumulation of data from the 
current year's report and data collected from previous annual reports. 
The final annual/close-out report at the conclusion of the 
authorization period (year seven) would also serve as the comprehensive 
close-out report and include both the final year annual use compared to 
annual authorization as well as a cumulative seven-year annual use 
compared to seven-year authorization. Information included in the 
annual reports may be used to inform future adaptive management of 
activities within the MITT Study Area.
    The Annual MITT Training Exercise Report and Testing Activity Navy 
report (classified or unclassified versions) could 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 would include:
    [ssquf] Marpi Reef and Chalan Kanoa Reef Geographic Mitigation 
Areas: The Navy would report the total hours of operation of MF1 
surface ship hull-mounted mid-frequency active sonar used in the Marpi 
Reef and Chalan Kanoa Reef Geographic Mitigation Areas from December to 
April; and

[ssquf] Major Training Exercises Notification

    The Navy would submit an electronic report to NMFS within fifteen 
calendar days after the completion of any major training exercise 
indicating: Location of the exercise; beginning and end dates of the 
exercise; and type of exercise.

Other Reporting and Coordination

    The Navy would continue to report and coordinate with NMFS for the 
following:
    [ssquf] Annual marine species monitoring technical review meetings 
that also include researchers and the Marine Mammal Commission 
(currently, every two years a joint Pacific-Atlantic meeting is held); 
and
    [ssquf] Annual Adaptive Management meetings that also include the 
Marine Mammal Commission (recently modified to occur in conjunction 
with the annual monitoring technical review meeting).

Preliminary Analysis and Negligible Impact Determination

General 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 by Level A or Level B harassment (as presented in Table 30), 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' 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, and ambient 
noise levels).
    In the Estimated Take of Marine Mammals section, we identified the 
subset of potential effects that would be expected to rise to the level 
of takes both annually and over the seven-year period covered by this 
proposed rule, and then identified the maximum number of harassment 
takes that are reasonably expected to occur 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 a disturbance, the health of impacted animals, 
the status of a species that incurs fitness-level impacts to 
individuals, etc.). For this proposed rule we evaluated the likely 
impacts of the enumerated maximum number of harassment takes that are 
proposed for authorization and reasonably expected to occur, in the 
context of the specific circumstances surrounding these predicted 
takes. Last, we collectively evaluated this information, as well as 
other more taxa-specific information and mitigation measure 
effectiveness, in group-specific assessments that support our 
negligible impact conclusions for each species.
    As explained in the Estimated Take of Marine Mammals section, no 
take by serious injury or mortality is requested or anticipated to 
occur.
    The Specified Activities reflect representative levels of training 
and testing activities. The Description of the Specified Activity 
section describes annual activities. 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 seven-year totals 
indicated in Table 30. We base our analysis and negligible impact 
determination on the

[[Page 5875]]

maximum number of takes that would be reasonably expected to occur and 
are proposed to be authorized, 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 Table 30, given that some of the 
anticipated effects of the Navy's training and testing activities on 
marine mammals are expected to be relatively similar in nature. 
However, below that, we break our analysis into species, or groups of 
species where relevant similarities exist, to provide more specific 
information related to the anticipated effects on individuals 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. 
Organizing our analysis by grouping species that share common traits or 
that will respond similarly to effects of the Navy's activities and 
then providing species-specific information allows us to avoid 
duplication while assuring that we have analyzed the effects of the 
specified activities on each affected species.
    The Navy's harassment take request is based on its model and 
quantitative assessment of mitigation, which NMFS reviewed and concurs, 
and appropriately predicts the maximum amount of harassment that is 
likely to occur. 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, independently reviewed, 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, 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 
harassment 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 seven-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, which means 
that the number of individuals taken is smaller than the total 
estimated takes. 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 of 
where a larger portion of a species is being taken by Navy activities, 
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 or more likely sequential. Where the number of instances of take 
is less than 100 percent of the abundance and there is no information 
to specifically suggest that a small subset of animals is being 
repeatedly taken over a high number of sequential days, the overall 
magnitude is generally considered relatively low, as it could on one 
extreme mean that every individual in the population will be taken on 
one day (a very minimal impact) or, more likely, that some are taken on 
one day annually, some are taken on a few not likely sequential days 
annually, and some are not taken at all.
    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, for some individuals of some species 
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, for some species 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 that individuals from most species would be 
taken over more than a few sequential days. This means that even where 
repeated takes of individuals are likely to occur, they are more likely 
to result from non-sequential exposures from different activities, and, 
even if sequential, individual animals are not predicted to be taken 
for more than several 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 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 a 
significant portion of the days of the year, much less that many of the 
days of disturbance would be sequential.
Physiological Stress Response
    Some of the lower level physiological stress responses (e.g., 
orientation or startle response, change in respiration, change in heart 
rate) discussed earlier would 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 harassment 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

[[Page 5876]]

mammals that could affect reproduction or survival.
Behavioral Response
    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' 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). The Navy 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 are used to predict how many instances 
of Level B behavioral harassment occur in a day. Take estimates alone 
do not 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 individual animals from 
sonar and other active sound sources during testing and training 
activities would be primarily from ASW events. It is important to note 
that 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 high-power 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 of Level B behavioral 
harassment (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. A less severe exposure 
of this nature 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. More severe effects could occur 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. Such effects 
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. However, such severe behavioral effects are 
expected to occur infrequently.
    To help assess this, for sonar (LFAS/MFAS/HFAS) used in the MITT 
Study Area, the Navy provided information estimating the percentage of 
animals that may be taken by Level B harassment under each behavioral 
response function that would occur within 6-dB increments (percentages 
discussed below in the Group and Species-Specific Analyses 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 other contextual factors (such as distance) are important 
also. The majority of Level B harassment 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. Because 
species belonging to taxa that share common characteristics are likely 
to respond and be affected in similar ways, these discussions are 
presented within each species group below in the Group and Species-
Specific Analyses section. As noted previously in this proposed rule, 
behavioral response is likely highly variable between species, 
individuals within a species, and context of the exposure. 
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 from Navy 
activities might necessarily be expected to potentially result in more 
severe responses (see the Group and Species-Specific Analyses section 
below for more detailed information). To fully understand the likely 
impacts of the predicted/proposed 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., whether they will occur for a longer duration over sequential 
days or the comparative sound level that will be received). 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
    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 NM from 
shore) and in waters greater than 600 ft deep. Additionally 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

[[Page 5877]]

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.
    That said, the MITT Study Area is different than other Navy ranges 
where there can be a significant number of Navy surface ships with 
hull-mounted sonar homeported. In the MITT Study Area, there are no 
homeported surface ships with hull-mounted sonars permanently assigned. 
There is no local unit level training in the MITT Study Area for 
homeported ships such as the case for other ranges. Instead, Navy 
activities from visiting and transiting vessels are much more episodic 
in the MITT Study Area. Therefore, there could be long gaps between 
activities (i.e., weeks, months) in the MITT Study Area.
    Durations of Navy activities utilizing tactical sonar sources and 
explosives vary and are fully described in Appendix A (Training and 
Testing Activity Descriptions) of the 2019 MITT DSEIS/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 include hull-mounted, towed, line array, 
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 MITT Study Area generally last for only a few hours. Some ASW 
training and testing can generally last for 2-10 days, or a 10-day 
exercise is typical for an MTE-Large Integrated ASW (see Table 3). For 
these multi-day exercises there will typically 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 Table 3). 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, or demonstrate 
sustained behavioral responses. 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 MITT training 
activities. They are stationary and conducted in deep, open water where 
fewer marine mammals would typically be expected to be encountered. 
They also have shutdown procedures and rigorous monitoring, i.e., 
during the activity, the Navy conducts passive acoustic monitoring and 
visually observes for marine mammals 90 min prior to the first firing, 
during the event, and 2 hrs after sinking the vessel. All of these 
factors make it unlikely that individuals would be exposed to the 
exercise for extended periods or on consecutive days.
Assessing the Number of Individuals Taken and the Likelihood of 
Repeated Takes
    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 by Level B harassment and the number of 
times those individuals are 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 species (or stock if applicable). For 
example, if there are 100 harassment 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 and 
expected 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 of where larger portions of the species 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. It also provides a relative picture of the 
scale of impacts to each species.
    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 could occur over the 
year with more resident species. Nonetheless, the episodic nature of 
Navy activities in the MITT Study Area would mean less frequent 
exposures as compared to some other ranges. While select offshore areas 
in the MITT Study Area are used more frequently for ASW and other 
activities, these are generally further offshore than where most island 
associated resident population would occur and instead would be in 
areas with more transitory species. In short, we expect that the total 
anticipated takes represent exposures of a smaller number of 
individuals of which some could 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 several sequential days (with a few possible exceptions 
discussed in the species-specific conclusions).
    When calculating the proportion of a population affected by takes 
(e.g., the number of takes divided by population abundance), which can 
also be helpful in estimating the number of days over which some 
individuals may be taken, it is important to choose an appropriate 
population estimate against which to make the comparison. The SARs, 
where available, 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). When the stock is known 
to range well outside of U.S. EEZ boundaries, population

[[Page 5878]]

estimates based on surveys conducted only within the U.S. EEZ are known 
to be underestimates. For marine mammal populations in the MITT Study 
Area there have been no specific stocks assigned to those populations 
and there are no associated SARs. There is also no information on 
trends for any of these species. The information used to estimate take 
includes the best available survey abundance data to model density 
layers. Accordingly, in calculating the percentage of takes versus 
abundance for each species in order to assist in understanding both the 
percentage of the species affected, as well as how many days across a 
year individuals could be taken, we use the data most appropriate for 
the situation. The survey data used to calculate abundance in the MITT 
Study Area is described in the Navy Marine Species Density Database 
Phase III for the Mariana Islands Training and Testing Study Area (Navy 
2018). 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. For example, 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.
Temporary Threshold Shift
    NMFS and the Navy have estimated that all species of marine mammals 
may sustain some level of TTS from active sonar. As mentioned 
previously, in general, 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 51-55 indicates the 
number of takes by TTS that may be incurred by different species from 
exposure to active sonar 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, which are the highest power and most 
numerous sources and the ones that cause the most take, utilize the 1-
10 kHz frequency band, which suggests that if TTS were to be induced by 
any of these MF sources it would be in a frequency band somewhere 
between approximately 2 and 20 kHz, which is in the range of 
communication calls for many odontocetes, but below the range of the 
echolocation signals used for foraging. 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), which 
could overlap with the range in which some odontocetes communicate or 
echolocate. 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 unlikely. There are fewer LF sources and the 
majority are used in the more readily mitigated testing environment, 
and TTS from LF sources would most likely occur below 2 kHz, which is 
in the range where many mysticetes communicate and also where other 
non-communication auditory cues are located (waves, snapping shrimp, 
fish prey). Also of note, the majority of sonar sources from which TTS 
may be incurred occupy a narrow frequency band, which means that the 
TTS incurred would also be across a narrower band (i.e., not affecting 
the majority of an animal's hearing range). This frequency provides 
information about the cues to which a marine mammal may be temporarily 
less sensitive, but not the degree or duration of sensitivity loss. 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 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) and the relative motion between the sonar 
vessel and the animal. In the TTS studies discussed in the proposed 
rule, 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 seconds, incurring those levels 
of TTS is highly unlikely. Since any hull-mounted sonar, such as the 
SQS-53, engaged in anti-submarine warfare training would be moving at 
between 10 and 15 knots and nominally pinging every 50 seconds, the 
vessel will have traveled a minimum distance of approximately 257 m 
during the time between those pings. A scenario could occur where an 
animal does not leave the vicinity of a ship or travels a course 
parallel to the ship, however, the close distances required make TTS 
exposure unlikely. For a Navy vessel moving at a nominal 10 knots, it 
is unlikely a marine mammal could maintain speed parallel to the ship 
and receive adequate energy over successive pings to suffer TTS.
    In short, given the anticipated duration and levels of sound 
exposure, we would not expect marine mammals to incur more than 
relatively low levels of TTS (i.e., single digits of sensitivity loss). 
To add context to this degree of TTS, individual marine mammals may 
regularly experience variations of 6dB differences in hearing 
sensitivity across time (Finneran et al., 2000, 2002; Schlundt et al., 
2000).
    3. Duration of TTS (recovery time)--In the TTS laboratory studies 
(as discussed in the proposed rule), 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 MITT 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

[[Page 5879]]

majority of the events and the speed of a typical vessel, especially 
given the fact that the higher power sources resulting in TTS are 
predominantly intermittent, which have been shown to result in shorter 
durations of TTS. Also, for the same reasons discussed in the 
Preliminary Analysis and Negligible Impact Determination--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 would not usually span the entire 
frequency range of one vocalization type, much less span all types of 
vocalizations or other critical auditory cues.
    Tables 51-55 indicates the number of incidental takes by TTS for 
each species that are likely to result from the Navy's activities. As a 
general point, the majority of these TTS takes are the result of 
exposure to hull-mounted MFAS (MF narrower band sources), with fewer 
from explosives (broad-band lower frequency sources), and even fewer 
from LF or HF sonar sources (narrower band). As described above, we 
expect the majority of these takes to be in the form of mild (single-
digit), short-term (minutes to hours), narrower band (only affecting a 
portion of the animal's hearing range) TTS. This means that for one to 
several times per year, for several minutes to maybe a few hours (high 
end) each, a taken individual will have slightly diminished hearing 
sensitivity (slightly more than natural variation, but nowhere near 
total deafness). More often than not, such an exposure would occur 
within a narrower mid- to higher frequency band that may overlap part 
(but not all) of a communication, echolocation, or predator range, but 
sometimes across a lower or broader bandwidth. The significance of TTS 
is also related to the auditory cues that are germane within the time 
period that the animal incurs the TTS--for example, if an odontocete 
has TTS at echolocation frequencies, but incurs it at night when it is 
resting and not feeding, for example, it is not impactful. In short, 
the expected results of any one of these small number of mild TTS 
occurrences could be that (1) it does not overlap signals that are 
pertinent to that animal in the given time period, (2) it overlaps 
parts of signals that are important to the animal, but not in a manner 
that impairs interpretation, or (3) it reduces detectability of an 
important signal to a small degree for a short amount of time--in which 
case the animal may be aware and be able to compensate (but there may 
be slight energetic cost), or the animal may have some reduced 
opportunities (e.g., to detect prey) or reduced capabilities to react 
with maximum effectiveness (e.g., to detect a predator or navigate 
optimally). However, given the small number of times that any 
individual might incur TTS, the low degree of TTS and the short 
anticipated duration, and the low likelihood that one of these 
instances would occur in a time period in which the specific TTS 
overlapped the entirety of a critical signal, it is unlikely that TTS 
of the nature expected to result from the Navy activities would result 
in behavioral changes or other impacts that would impact any 
individual's (of any hearing sensitivity) reproduction or survival.
Auditory Masking or Communication Impairment
    The ultimate potential impacts of masking on an individual (if it 
were to occur) are similar to those discussed for TTS, but an important 
difference is that masking only occurs during the time of the signal, 
versus TTS, which continues beyond the duration of the signal. 
Fundamentally, masking is referred to as a chronic effect because one 
of the key harmful components of masking is its duration--the fact that 
an animal would have reduced ability to hear or interpret critical cues 
becomes much more likely to cause a problem the longer it is occurring. 
Also inherent in the concept of masking is the fact that the potential 
for the effect is only present during the times that the animal and the 
source are in close enough proximity for the effect to occur (and 
further, this time period would need to coincide with a time that the 
animal was utilizing sounds at the masked frequency). As our analysis 
has indicated, because of the relative movement of vessels and the 
species involved in this rule, we do not expect the exposures with the 
potential for masking to be of a long duration. In addition, masking is 
fundamentally more of a concern at lower frequencies, because low 
frequency signals propagate significantly further than higher 
frequencies and because they are more likely to overlap both the 
narrower LF calls of mysticetes, as well as many non-communication cues 
such as fish and invertebrate prey, and geologic sounds that inform 
navigation. It should be noted that the Navy is only proposing 
authorization for a small subset of more narrow frequency LF sources 
and for less than 11 hours cumulatively annually. Masking is also more 
of a concern from continuous sources (versus intermittent sonar 
signals) where there is no quiet time between pulses within which 
auditory signals can be detected and interpreted. For these reasons, 
dense aggregations of, and long exposure to, continuous LF activity are 
much more of a concern for masking, whereas comparatively short-term 
exposure to the predominantly intermittent pulses of often narrow 
frequency range MFAS or HFAS, or explosions are not expected to result 
in a meaningful amount of masking. While the Navy occasionally uses LF 
and more continuous sources, it is not in the contemporaneous aggregate 
amounts that would accrue to a masking concern. Specifically, the 
nature of the activities and sound sources used by the Navy do not 
support the likelihood of a level of masking accruing that would have 
the potential to affect reproductive success or survival. Additional 
detail is provided below.
    Standard hull-mounted MFAS typically pings every 50 seconds. Some 
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) where 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 other sources, 
the pulse length is significantly shorter than hull-mounted active 
sonar, on the order of several microseconds to tens of milliseconds. 
Some of the vocalizations that many marine mammals make are less than 
one second long, so, for example with hull-mounted sonar, there would 
be a 1 in 50 chance (only if the source was in close enough proximity 
for the sound to exceed the signal that is being detected) that a 
single vocalization might be masked by a ping. However, when 
vocalizations (or series of vocalizations) are longer than one second, 
masking would not occur. Additionally, 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. A few 
systems operate with higher duty cycles or

[[Page 5880]]

nearly continuously, but they typically use lower power, which means 
that an animal would have to be closer, or in the vicinity for a longer 
time, to be masked to the same degree as by a higher level source. 
Nevertheless, masking could occasionally occur at closer ranges to 
these high-duty cycle and continuous active sonar systems, but as 
described previously, it would be expected to be of a short duration 
when the source and animal are in close proximity. While data are 
lacking on behavioral responses of marine mammals to continuously 
active sonars, mysticete species are known to be able to habituate to 
novel and continuous sounds (Nowacek et al., 2004), suggesting that 
they are likely to have similar responses to high-duty cycle sonars. 
Furthermore, most of these systems are hull-mounted on surface ships 
and ships are moving at least 10 kn and it is unlikely that the ship 
and the marine mammal would continue to move in the same direction and 
it be subjected to the same exposure due to that movement. 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. HF signals (above 10 kHz) attenuate more rapidly 
in the water due to absorption than do lower frequency signals, thus 
producing only a very small zone of potential masking. If masking or 
communication impairment were to occur briefly, it would more likely be 
in the frequency range of MFAS (the more powerful source), which 
overlaps with some odontocete vocalizations (but few mysticete 
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 single marine mammal species' vocalizations.
    Other sources used in Navy training and testing that are not 
explicitly addressed above, 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.
    In conclusion, masking is more likely to occur in the presence of 
broadband, relatively continuous noise sources such as from vessels, 
however, the duration of temporal and spatial overlap with any 
individual animal and the spatially separated sources that the Navy 
uses would not be expected to result in more than short-term, low 
impact masking that would not affect reproduction or survival.
PTS From Sonar Acoustic Sources and Explosives and Tissue Damage From 
Explosives
    Tables 51 through 55 indicate the number of individuals of each 
species for which Level A harassment in the form of PTS resulting from 
exposure to active sonar and/or explosives is estimated to occur. The 
number of individuals to potentially incur PTS annually (from sonar and 
explosives) for each species ranges from 0 to 50 (50 is for Dwarf sperm 
whale), but is more typically 0 or 1. No species have the potential to 
incur tissue damage from explosives.
    Data suggest 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 
has determined 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. 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. As 
discussed previously, the Navy utilized a post-modeling quantitative 
assessment to adjust the take estimates based on avoidance and the 
likely success of some portion of the mitigation measures. As is 
typical in predicting biological responses, it is challenging to 
predict exactly how avoidance and mitigation will affect the take of 
marine mammals, and therefore the Navy erred on the side of caution in 
choosing a method that would more likely still overestimate the take by 
PTS to some degree. Nonetheless, these modified Level A harassment take 
numbers represent the maximum number of instances in which marine 
mammals would be reasonably expected to incur PTS, and we have analyzed 
them accordingly.
    If a marine mammal is able to approach a surface vessel within the 
distance necessary to incur PTS in spite of the mitigation measures, 
the likely speed of the vessel (nominally 10-15 kn) and relative motion 
of the vessel 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 discussed previously in relation to TTS, the 
likely consequences to the health of an individual that incurs PTS can 
range from mild to more serious dependent upon the degree of PTS and 
the frequency band it is in. The majority of any PTS incurred as a 
result of exposure to Navy sources would be expected to be in the 2-20 
kHz range (resulting from the most powerful hull-mounted sonar) and 
could overlap a small portion of the communication frequency range of 
many odontocetes, whereas other marine mammal groups have communication 
calls at lower frequencies. Regardless of the frequency band though, 
the more important point in this case is that any PTS accrued as a 
result of exposure to Navy activities would be expected to be of a 
small amount (single digits). Permanent loss of some degree of hearing 
is a normal occurrence for older animals, and many animals are able to 
compensate for the shift, both in old age or at younger ages as the 
result of stressor exposure. While a small loss of hearing sensitivity 
may include some degree of energetic costs for compensating or may mean 
some small loss of opportunities or detection capabilities, at the 
expected scale it would be unlikely to impact behaviors, opportunities, 
or detection capabilities to a degree that would interfere with 
reproductive success or survival.
    The Navy implements mitigation measures (described in the Proposed 
Mitigation Measures section) during explosive activities, including 
delaying detonations when a marine mammal is observed in the mitigation 
zone. Nearly all explosive events would occur during daylight hours to 
improve the sightability of marine mammals and thereby improve 
mitigation effectiveness. Observing for marine mammals during the 
explosive activities would include visual 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 NM for sinking exercise (see Tables 36-44). For

[[Page 5881]]

all of these reasons, the proposed mitigation measures associated with 
explosives are expected to be effective in preventing tissue damage to 
any potentially affected species, and no species are anticipated to 
incur tissue damage during the period of the proposed rule.

Group and Species-Specific Analyses

    The maximum amount and type of incidental take of marine mammals 
reasonably likely to occur from exposure to sonar and other active 
acoustic sources and explosions and therefore proposed to be authorized 
during the seven-year training and testing period are shown in Table 
30. The vast majority of predicted exposures (greater than 99 percent) 
are expected to be Level B harassment (TTS and behavioral reactions) 
from acoustic and explosive sources during training and testing 
activities at relatively low received levels.
    In the discussions below, the estimated Level B harassment takes 
represent instances of take, not the number of individuals taken (the 
much lower and less frequent Level A harassment takes are far more 
likely to be associated with separate individuals), and in some cases 
individuals may be taken more than one time. Below, we compare the 
total take numbers (including PTS, TTS, and behavioral disruption) for 
species to their associated abundance estimates to evaluate the 
magnitude of impacts across the species and to individuals. 
Specifically, when an abundance percentage comparison is below 100, it 
means that that percentage or less of the individuals will be affected 
(i.e., some individuals will not be taken at all), that the average for 
those taken is one day per year, and that we would not expect any 
individuals to be taken more than a few times in a year.
    To assist in understanding what this analysis means, we clarify a 
few issues related to estimated takes and the analysis here. An 
individual that incurs a PTS or TTS take may sometimes, for example, 
also be subject to behavioral disturbance at the same time. As 
described above in this section, the degree of PTS, and the degree and 
duration of TTS, expected to be incurred from the Navy's activities are 
not expected to impact marine mammals such that their reproduction or 
survival could be affected. Similarly, data do not suggest that a 
single instance in which an animal accrues PTS or TTS and is subject to 
behavioral disturbance would result in impacts to reproduction or 
survival. Alternately, we recognize that if an individual is subjected 
to behavioral disturbance repeatedly for a longer duration and on 
consecutive days, effects could accrue to the point that reproductive 
success is jeopardized, although those sorts of impacts are not 
expected to result from these activities. Accordingly, in analyzing the 
number of takes and the likelihood of repeated and sequential takes, we 
consider the total takes, not just the Level B harassment takes by 
behavioral disruption, so that individuals potentially exposed to both 
threshold shift and behavioral disruption are appropriately considered. 
The number of Level A harassment takes by PTS are so low (and zero in 
most cases) compared to abundance numbers that it is considered highly 
unlikely that any individual would be taken at those levels more than 
once.
    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 that 
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) and scale (i.e., multiple sonar 
platforms) of the MTEs. On the less severe end, exposure to 
comparatively lower levels of sound at a detectably greater distance 
from the animal, for a few or several minutes, could result in a 
behavioral response such as avoiding an area that an animal would 
otherwise have moved through or fed in, or breaking off one or a few 
feeding bouts. More severe behavioral effects could occur when an 
animal gets close enough to the source to receive a comparatively 
higher level of sound, is exposed continuously to one source for a 
longer time, or is exposed intermittently to different sources 
throughout a day. Such effects 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. However, such 
severe behavioral effects are expected to occur infrequently.
    Occasional, milder 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 severe responses, if they are not expected to 
be repeated over sequential days, impacts to individual fitness are not 
anticipated. Nearly all studies and experts agree that infrequent 
exposures of a single day or less are unlikely to impact an 
individual's overall energy budget (Farmer et al., 2018; Harris et al., 
2017; King et al., 2015; NAS 2017; New et al., 2014; Southall et al., 
2007; Villegas-Amtmann et al., 2015).
    The analyses below in some cases address species collectively if 
they occupy the same functional hearing group (i.e., low, mid, and 
high-frequency cetaceans), share similar life history strategies, and/
or are known to behaviorally respond similarly to acoustic stressors. 
Because some of these groups or species share characteristics that 
inform the impact analysis similarly, it would be duplicative to repeat 
the same analysis for each species. In addition, similar species 
typically have the same hearing capabilities and behaviorally respond 
in the same manner.
    Thus, our analysis below considers the effects of the Navy's 
activities on each affected species even where discussion is organized 
by functional hearing group and/or information is evaluated at the 
group level. Where there are meaningful differences between a species 
that would further differentiate the analysis, they are either 
described within the section or the discussion for those species is 
included as a separate subsection. Specifically below, we first give 
broad descriptions of the mysticete and odontocete groups and then 
differentiate into further groups and species as appropriate.
Mysticetes
    This section builds on the broader discussion above and brings 
together the discussion of the different types and amounts of take that 
different species will incur, the applicable mitigation for species, 
and the status of the species to support the negligible impact 
determinations. We have described (above in this section) the 
unlikelihood of any masking having effects that would impact the 
reproduction or survival of any of the individual marine mammals 
affected by the Navy's activities. For mysticetes, there is no 
predicted PTS from sonar or explosives and no predicted tissue damage 
from explosives for any species. Much of the discussion below focuses 
on the behavioral effects and the mitigation measures that reduce the 
probability or severity of effects. Because there are species-specific 
factors in relation to the status of the species, at the end of the 
section we break out our findings on a species-specific basis.
    In Table 51 below for mysticetes, we indicate for each species the 
Level A

[[Page 5882]]

and Level B harassment numbers, and a number indicating the instances 
of total take as a percentage of abundance in the MITT Study Area 
alone, as well as the MITT Study Area plus the transit corridor, which 
was calculated separately. While the density used to calculate take is 
the same for these two areas, the takes were calculated separately for 
the two areas for all species in this proposed rule, not just 
mysticetes, because the activity levels are higher in the MITT Study 
Area and it is helpful to understand the comparative impacts in the two 
areas.

   Table 51--Annual Estimated Takes by Level B Harassment and Level A Harassment for Mysticetes and Number Indicating the Instances of Total Take as a
                                                             Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Instances of indicated types of incidental take  (not all takes          Abundance          Instances of total take
                                       represent separate individuals, especially for disturbance)   --------------------------     as  percentage of
                                    -----------------------------------------------------------------                                   abundance
                                        Level B  harassment      Level A           Total takes                                 -------------------------
              Species               --------------------------  harassment --------------------------               MITT study
                                                              -------------               MITT study   MITT study     area +                  MITT study
                                      Behavioral                             MITT study     area +        area       transit     MITT study     area +
                                     disturbance      TTS          PTS          area       transit                   corridor       area       transit
                                                                                           corridor                                            corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale.........................            4           20            0           24           24          179          200           13           12
Bryde's whale......................           40          258            0          296          297        1,470        1,595           20           19
Fin whale..........................            5           20            0           25           25          215          240           12           10
Humpback whale.....................           57          422            0          476          479        3,190        3,563           15           13
Minke whale........................           10           85            0           95           95          538          601           18           16
Omura's whale......................            4           25            0           28           28          143          160           20           18
Sei whale..........................           19          136            0          154          155        1,040        1,094           15           14
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
  transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
  Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
  B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
  Estimated Take of Marine Mammals section.

    The majority of takes by harassment of mysticetes in the MITT Study 
Area are caused by sources from the MF1 active sonar bin (which 
includes hull-mounted sonar) because they are high level, narrowband 
sources in the 1-10 kHz range, which intersect what is estimated to be 
the most sensitive area of hearing for mysticetes. They also are used 
in a large portion of exercises (see Table 1.5-1 in the Navy's 
application). Most of the takes (66 percent) from the MF1 bin in the 
MITT Study Area would result from received levels between 154 and 172 
dB SPL, while another 33 percent would result from exposure between 172 
and 178 dB SPL. For the remaining active sonar bin types, the 
percentages are as follows: LF4 = 97 percent between 124 and 136 dB 
SPL, MF4 = 99 percent between 136 and 154 dB SPL, MF5 = 98 percent 
between 118 and 142 dB SPL, and HF4 = 98 percent between 100 and 148 dB 
SPL. These values may be derived from the information in Tables 6.4-8 
through 6.4-12 in the Navy's rulemaking/LOA application (though they 
were provided directly to NMFS upon request). No blue whales or fin 
whales will be taken by Level B harassment or PTS as a result of 
exposure to explosives. For other mysticetes, exposure to explosives 
will result in small numbers of take: 1-6 Level B behavioral harassment 
takes per species, 0-3 TTS takes per species (0 for sei whales), and 0 
PTS takes.
    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 feeding or breeding grounds. Behavioral reactions may include 
alerting, breaking off feeding dives and surfacing, diving or swimming 
away, or no response at all (DOD, 2017; Nowacek, 2007; Richardson, 
1995; Southall et al., 2007). Overall, mysticetes have been observed to 
be more reactive to acoustic disturbance when a noise source is located 
directly on their migration route. Mysticetes disturbed while migrating 
could pause their migration or route around the disturbance, while 
males en route to breeding grounds have been shown to be less 
responsive to disturbances. Although some may pause temporarily, they 
will resume migration shortly after the exposure ends. 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. Alternately, 
adult females with calves may be more responsive to stressors. As noted 
in the Potential Effects of Specified Activities on Marine Mammals and 
Their Habitat section, 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 less likely to show a visible response to sonar exposures at 
certain levels when feeding than when traveling. However, Goldbogen et 
al. (2013) indicated some horizontal displacement of deep foraging blue 
whales in response to simulated MFA sonar. Most Level B behavioral 
harassment of mysticetes is likely to be short-term and of low to 
sometimes moderate severity, with no anticipated effect on reproduction 
or survival from Level B harassment.
    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 do not typically use the same training locations day-after-
day during multi-day activities, except periodically in instrumented 
ranges. Therefore, displaced animals could return quickly after the MTE 
finishes. Due to the limited number and geographic scope of MTEs, it is 
unlikely that most mysticetes would encounter an MTE more than once per 
year and additionally, total hull-mounted sonar hours would be limited 
in several areas that are important to mysticetes (described below). In 
the ocean, the use of Navy sonar and other active acoustic sources is 
transient and is unlikely to expose the same population of animals 
repeatedly over a short period of time, especially given the broader-
scale movements of mysticetes.
    The implementation of procedural mitigation and the sightability of

[[Page 5883]]

mysticetes (due to their large size) further reduces the potential for 
a significant behavioral reaction or a threshold shift to occur (i.e., 
shutdowns are expected to be successfully implemented), which is 
reflected in the amount and type of incidental take that is anticipated 
to occur and proposed to be authorized.
    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 the vast majority of threshold shifts caused by Navy 
sonar sources will typically occur in the range of 2-20 kHz (from the 
1-10 kHz MF1 bin, though in a specific narrow band within this range as 
the sources are narrowband), 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. Additionally, many of the other critical sounds that 
serve as cues for navigation and prey (e.g., waves, fish, 
invertebrates) occur below a few kHz, which means that detection of 
these signals will not be inhibited by most threshold shift either. 
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 
reproduction or survival rates of mysticetes from exposure to sonar and 
other active acoustic sources.
    All the species discussed in this section would benefit from the 
procedural mitigation measures described earlier in the Proposed 
Mitigation Measures section. In addition, the Navy would limit 
activities and employ other measures in mitigation areas that would 
avoid or reduce impacts to mysticetes. The Navy would implement time/
area mitigation for explosives for humpback whales in the Marpi and 
Chalan Kanoa Reef Geographic Mitigation Areas as by prohibiting 
explosives year-round. The Navy would also implement the Marpi and 
Chalan Kona Reef Awareness Notification Message Areas that would avoid 
interactions with large whales that may be vulnerable to vessel 
strikes. This is especially important for humpback whales that are 
concentrated in these areas for breeding and calving.
    Below we compile and summarize the information that supports our 
preliminary determination that the Navy's activities would not 
adversely affect any species through effects on annual rates of 
recruitment or survival for any of the affected mysticete species.
    Humpback whale-- Effective as of October 11, 2016, NMFS changed the 
status of all humpback whales from an endangered species to a specific 
status for each of the 14 identified distinct population segments 
(DPSs) (81 FR 62259). The humpback whales in the MITT Study Area are 
indirectly addressed in the Alaska SAR, given that the historic range 
of humpbacks in the ``Asia wintering area'' includes the Mariana 
Islands. The observed presence of humpback whales in the Mariana 
Islands (Hill et al., 2016a; Hill et al., 2017a; Hill et al., 2018; 
Klinck et al., 2016a; Munger et al., 2014; NMFS, 2018; Oleson et al., 
2015; Uyeyama, 2014) are consistent with the MITT Study Area as a 
plausible migratory destination for humpback whales from Alaska (Muto 
et al., 2017a). It is likely that humpback whales in the Mariana 
Islands are part of the endangered Western North Pacific DPS (WNP DPS) 
based on the best available science (Bettridge et al., 2015; 
Calambokidis et al., 2008; Calambokidis et al., 2010; Carretta et al., 
2017b; Hill et al., 2017b; Muto et al., 2017a; NMFS, 2016a; NOAA, 
2015b; Wade et al., 2016) although the breeding range of the WNP DPS is 
not fully resolved. Individual photo-identification data for whales 
sampled off Saipan within the Mariana Archipelago in February-March 
2015 to 2018, suggest that these whales belong to the WNP DPS (Hill et 
al., in review). Specifically, comparisons with existing WNP humpback 
whale photo-identification catalogs showed that 11 of 41 (27 percent) 
whales within the Mariana Archipelago humpback whale catalog were 
previously sighted in WNP breeding areas (Japan and Philippines) and/or 
in a WNP feeding area off Russia (Hill et al., in review). No ESA 
designated critical habitat has been proposed for the WNP DPS in the 
MITT Study Area, although critical habitat has been proposed in Alaska 
(84 FR 54534; October 9, 2019). There are no designated biologically 
important areas; however, it is known that the areas of Marpi and 
Chalan Kanoa Reefs (out to the 400 m isobath) are being specifically 
used by mother/calf pairs of humpback whales (Hill et al., 2016, 2017, 
2018, in-press). Currently, no other areas have been identified for 
mother/calf pairs of humpback whales in the Mariana Islands.
    The shallower water (less than 400 m) surrounding the Chalan Kanoa 
Reef and Marpi Reef Geographic Mitigation Areas have not been a high-
use area for Navy MTEs and ASW training events as the area is 
considered generally unsuitable for training needs. These areas 
encompass water depths less than 400 m, with significant parts of the 
mitigation areas less than 200 m. The distance between 400 and 200 m 
isobaths is very small (between 0.5 and 2 nm). Most humpback whale 
sightings in or near the mitigation areas were within the 200 m 
isobath. The Navy typically conducts ASW that would also include the 
use of surface ship hull-mounted sonar such as MF1 in water depths 
greater than 200 m. Small scale and unit level ASW training is not 
conducted within 3 nm of land (e.g., Small Joint Coordinated ASW 
exercise, Tracking Exercise-surface ship). MTEs almost always use 
established range subareas far offshore and well outside of 3 nm of 
land. Close to half of the Chalan Kanoa Reef Geographic Mitigation Area 
is 3 nm from land making this area less suitable to current Navy ASW 
training needs. In addition, portions of the Chalan Kanoa Reef area 
have established anchorages and presence of anchored vessels is not 
conducive for ASW training with MF1 MFAS. Similarly, water depths less 
than 200 m at Marpi Reef are also typically unsuited for current ASW 
training needs, especially for group events. As part of proposed 
mitigation, the Navy would not use explosives in these two Geographic 
Mitigation Areas. Reducing exposure of humpback whales to explosive 
detonations in these areas and at this time is expected to reduce the 
likelihood of impacts that could affect reproduction or survival, by 
minimizing impacts on calves during this sensitive life stage, avoiding 
the additional energetic costs to mothers of avoiding the area during 
explosive exercises, and minimizing the chances that important breeding 
behaviors are interrupted to the point that reproduction is inhibited 
or abandoned for the year, or otherwise interfered with.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance (measured against both the MITT Study Area 
abundance and the MITT Study Area plus the transit corridor combined) 
is 15 and 13 percent, respectively (Table 51). Regarding the severity 
of those individual takes by Level B behavioral harassment, we have 
explained that the duration of any exposure is expected to be between 
minutes and hours (i.e., relatively short) and the received sound 
levels largely below 172 dB with a portion up to 178 dB (i.e., of a 
moderate or lower level, less likely to evoke a severe response). 
Regarding the severity of TTS takes, they are expected to be

[[Page 5884]]

low-level, of short duration, and mostly not in a frequency band that 
would be expected to interfere with communication or other important 
low-frequency cues. Therefore the associated lost opportunities and 
capabilities are not at a level that would impact reproduction or 
survival.
    Given the general lack of suitability of the shallow waters of 
Marpi and Chalan Kanoa Reefs for Navy's activities, it is predicated 
that only a small portion of individuals would be taken and disturbed 
at a low-moderate level, with those individuals disturbed only once. 
There is no expected Level A harassment. This low magnitude and 
severity of harassment effects is not expected to result in impacts on 
the reproduction or survival of any individuals and, therefore, the 
total take is not expected to adversely affect this species through 
impacts on annual rates of recruitment or survival. No mortality or 
tissue damage is anticipated or proposed to be authorized. For these 
reasons, we have determined, in consideration of all of the effects of 
the Navy's activities combined, that the proposed authorized take would 
have a negligible impact on humpback whales.
    Blue whale--Blue whales are listed as endangered under the ESA 
throughout their range, but there is no ESA designated critical habitat 
or biologically important areas identified for this species in the MITT 
Study Area. There are no recent sighting records for blue whales in the 
MITT Study Area (Fulling et al., 2011; Hill et al., 2017a; Uyeyama, 
2014). Some acoustic detections from passive monitoring devices 
deployed at Saipan and Tinian have recorded the presence of blue whales 
over short periods of time (a few days) (Oleson et al., 2015). However, 
since blue whale calls can travel very long distances (up to 621 mi 
(1,000 km)), it is unknown whether the animals were within the MITT 
Study Area. Blue whales would be most likely to occur in the MITT Study 
Area during the winter and are expected to be few in number.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance (measured against both the MITT Study Area 
abundance and the MITT Study Area plus the transit corridor combined) 
is 13 and 12 percent, respectively (Table 51). Regarding the severity 
of those individual takes by Level B behavioral harassment, we have 
explained that the duration of any exposure is expected to be between 
minutes and hours (i.e., relatively short) and the received sound 
levels largely below 172 dB with a portion up to 178 dB (i.e., of a 
moderate or lower level, less likely to evoke a severe response). 
Regarding the severity of TTS takes, they are expected to be low-level, 
of short duration, and mostly not in a frequency band that would be 
expected to interfere with communication or other important low-
frequency cues. Therefore the associated lost opportunities and 
capabilities are not at a level that would impact reproduction or 
survival.
    Given the range of blue whales and the low abundance in the MITT 
Study Area, this information suggests that a very small portion of 
individuals would be taken and disturbed at a low-moderate level, with 
those individuals disturbed only once. There is no expected Level A 
harassment. This low magnitude and severity of harassment effects is 
not expected to result in impacts on the reproduction or survival of 
any individuals and, therefore, the total take is not expected to 
adversely affect this species through impacts on annual rates of 
recruitment or survival. No mortality or tissue damage is anticipated 
or proposed to be authorized. For these reasons, we have determined, in 
consideration of all of the effects of the Navy's activities combined, 
that the proposed authorized take would have a negligible impact on 
blue whales.
    Fin whale--Fin whales are listed as endangered under the ESA 
throughout their range, but there is no ESA designated critical habitat 
or biologically important areas identified for this species in the MITT 
Study Area. There are no sighting records for fin whales in the MITT 
Study Area (Fulling et al., 2011; Hill et al., 2017a; Oleson et al., 
2015; Uyeyama, 2014). Based on acoustic detections, fin whales are 
expected to be present in the MITT Study Area although few in number. 
Acoustic detections from passive monitoring devices deployed at Saipan 
and Tinian have recorded the presence of fin whales over short (a few 
days) periods of time (Oleson et al., 2015), and fin whale 
vocalizations were detected in January 2010 in the Transit Corridor 
between Hawaii and Guam (Oleson and Hill, 2010a). Regarding the 
magnitude of Level B harassment takes (TTS and behavioral disruption), 
the number of estimated total instances of take compared to the 
abundance (measured against both the MITT Study Area abundance and the 
MITT Study Area plus the transit corridor combined) is 12 and 10 
percent, respectively (Table 51). Regarding the severity of those 
individual takes by Level B behavioral harassment, we have explained 
that the duration of any exposure is expected to be between minutes and 
hours (i.e., relatively short) and the received sound levels largely 
below 172 dB with a portion up to 178 dB (i.e., of a moderate or lower 
level, less likely to evoke a severe response). Regarding the severity 
of TTS takes, they are expected to be low-level, of short duration, and 
mostly not in a frequency band that would be expected to interfere with 
communication or other important low-frequency cues. Therefore, the 
associated lost opportunities and capabilities are not at a level that 
would impact reproduction or survival.
    Given the low abundance of fin whales in the MITT Study Area, this 
information suggests that a very small portion of individuals would be 
taken and disturbed at a low-moderate level, with those individuals 
disturbed only once. There is no expected Level A harassment. This low 
magnitude and severity of harassment effects is not expected to result 
in impacts on the reproduction or survival of any individuals and, 
therefore, the total take is not expected to adversely affect this 
species through impacts on annual rates of recruitment or survival. No 
mortality or tissue damage is anticipated or proposed to be authorized. 
For these reasons, we have determined, in consideration of all of the 
effects of the Navy's activities combined, that the proposed authorized 
take would have a negligible impact on fin whales.
    Sei whale--Sei whales are listed as endangered under the ESA 
throughout their range, but there is no ESA designated critical habitat 
or biologically important areas identified for this species in the MITT 
Study Area. In the 2007 survey of the Mariana Islands (Fulling et al., 
2011), a total of 16 sei whales were sighted in coverage of 
approximately 24 percent of the MITT Study Area. Sei whales were also 
visually detected in the Transit Corridor between the MITT Study Area 
and Hawaii during a NMFS survey in January 2010 (Oleson and Hill, 
2010a). Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance (measured against both the MITT Study Area 
abundance and the MITT Study Area plus the transit corridor combined) 
is 15 and 14 percent, respectively (Table 51). Regarding the severity 
of those individual takes by Level B behavioral harassment, we have 
explained that the duration of any exposure is expected to be between 
minutes and hours (i.e., relatively short) and the received sound 
levels largely below 172 dB with a

[[Page 5885]]

portion up to 178 dB (i.e., of a moderate or lower level, less likely 
to evoke a severe response). Regarding the severity of TTS takes, they 
are expected to be low-level, of short duration, and mostly not in a 
frequency band that would be expected to interfere with communication 
or other important low-frequency cues. Therefore the associated lost 
opportunities and capabilities are not at a level that would impact 
reproduction or survival.
    Given the low occurrence of sei whales in the MITT Study Area, this 
information suggests that a very small portion of individuals would be 
taken and disturbed at a low-moderate level, with those individuals 
disturbed only once. There is no expected Level A harassment. This low 
magnitude and severity of harassment effects is not expected to result 
in impacts on the reproduction or survival of any individuals and, 
therefore, the total take is not expected to adversely affect this 
species through impacts on annual rates of recruitment or survival. No 
mortality or tissue damage is anticipated or proposed to be authorized. 
For these reasons, we have determined, in consideration of all of the 
effects of the Navy's activities combined, that the proposed authorized 
take would have a negligible impact on sei whales.
    Bryde's whale, Minke whale, Omura's whale--These whales are not 
listed as endangered or threatened under the ESA. Bryde's whale are 
expected to be present in the MITT Study Area based on sighting records 
(Fulling et al., 2011; Hill et al., 2017a; Mobley, 2007; Oleson and 
Hill, 2010a; Uyeyama, 2014). Bryde's whales were detected in the 
Transit Corridor between the MITT Study Area and Hawaii during a NMFS 
survey in January 2010 (Oleson and Hill, 2010a). Bryde's whales were 
also encountered off Rota during a small boat non-systematic survey in 
August-September 2015 (Hill et al., 2017a). Minke whales have not been 
visually detected in the MITT Study Area during any known survey 
efforts within approximately the last decade (Fulling et al., 2011; 
Hill et al., 2011; Hill et al., 2013; Hill et al., 2014; Hill et al., 
2015; Hill et al., 2017a; Mobley, 2007; Oleson and Hill, 2010a; Tetra 
Tech Inc., 2014; Uyeyama, 2014). However, acoustic data collected 
during line-transect surveys did detect calling minke whales (Norris et 
al., 2017). Omura's whale is thought to be present in the MITT Study 
Area, but no data is available to estimate abundance.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance (measured against both the MITT Study Area 
abundance and the MITT Study Area plus the transit corridor combined) 
is 18-20 and 16-19 percent, respectively (Table 51). Regarding the 
severity of those individual takes by Level B behavioral harassment, we 
have explained that the duration of any exposure is expected to be 
between minutes and hours (i.e., relatively short) and the received 
sound levels largely below 172 dB with a portion up to 178 dB (i.e., of 
a moderate or lower level, less likely to evoke a severe response). 
Regarding the severity of TTS takes, they are expected to be low-level, 
of short duration, and mostly not in a frequency band that would be 
expected to interfere with communication or other important low-
frequency cues. Therefore the associated lost opportunities and 
capabilities are not at a level that would impact reproduction or 
survival.
    Given the low occurrence of Bryde's whales and minke whales and the 
low abundance of Omura's whales in the MITT Study Area, this 
information suggests that a small portion of individuals would be taken 
and disturbed at a low-moderate level, with those individuals disturbed 
only once. There is no expected Level A harassment. This low magnitude 
and severity of harassment effects is not expected to result in impacts 
on the reproduction or survival of any individuals and, therefore, the 
total take is not expected to adversely affect these species through 
impacts on annual rates of recruitment or survival. No mortality or 
tissue damage is anticipated or proposed to be authorized. For these 
reasons, we have determined, in consideration of all of the effects of 
the Navy's activities combined, that the proposed authorized take would 
have a negligible impact on Bryde's whales, minke whales, and Omura's 
whales.
    Altogether, no mortality or Level A harassment is anticipated or 
proposed to be authorized. Regarding the magnitude of Level B 
harassment takes (TTS and behavioral disruption), the number of 
estimated total instances of take compared to the abundance is 20 
percent or less for all mysticetes in the MITT Study Area and 19 
percent or less in the MITT Study Area and transit corridor combined 
(Table 51). Regarding the severity of those individual Level B 
harassment takes by behavioral disruption, the duration of any exposure 
is expected to be between minutes and hours (i.e., relatively short) 
and the received sound levels largely below 172 dB with a portion up to 
178 dB (i.e., of a moderate or lower level, less likely to evoke a 
severe response). Regarding the severity of TTS takes, they are 
expected to be low-level, of short duration, and mostly not in a 
frequency band that would be expected to interfere with communication 
or other important low-frequency cues. Therefore, the associated lost 
opportunities and capabilities are not at a level that would impact 
reproduction or survival.
    Only a small portion of any mysticete population is anticipated to 
be impacted, and any individual whale is likely to be disturbed at a 
low-moderate level, with the taken individuals likely exposed on one 
day or perhaps over a few days for a small number of individuals, with 
little chance that any are taken across sequential days. This low 
magnitude and severity of harassment effects is unlikely to result in 
impacts on individual reproduction or survival, much less annual rates 
of recruitment or survival of any of the species. For these reasons, we 
have preliminarily determined, in consideration of all of the effects 
of the Navy's activities combined, that the proposed authorized take 
would have a negligible impact on all of the mysticete species.
Odontocetes
    This section builds on the broader discussion above and brings 
together the discussion of the different types and amounts of take that 
different species would incur, the applicable mitigation for each 
species, and the status of the species to support the negligible impact 
determinations for each species. We have previously described the 
unlikelihood of any masking or habitat impacts having effects that 
would impact the reproduction or survival of any of the individual 
marine mammals affected by the Navy's activities. Here, we include 
information that applies to all of the odontocete species, which are 
then further divided and discussed in more detail in the following 
subsections: Dwarf sperm whales and pygmy sperm whales; sperm whales; 
beaked whales; and dolphins and small whales. These subsections include 
more specific information about the groups, as well as conclusions for 
each species represented.
    The majority of takes by harassment of odontocetes in the MITT 
Study Area are caused by sources from the MF1 active sonar bin (which 
includes hull-mounted sonar) because they are high level, typically 
narrowband sources at a frequency (in the 1-10 kHz range) that overlaps 
a more sensitive portion (though not the most sensitive) of the MF 
hearing range and they are used in a large portion of exercises (see 
Table 1.5-1 in the Navy's rulemaking/LOA

[[Page 5886]]

application). For odontocetes other than beaked whales (for which these 
percentages are indicated separately in that section), most of the 
takes (98 percent) from the MF1 bin in the MITT Study Area would result 
from received levels between 154 and 172 dB SPL. For the remaining 
active sonar bin types, the percentages are as follows: LF4 = 97 
percent between 124 and 136 dB SPL, MF4 = 99 percent between 136 and 
160 dB SPL, MF5 = 97 percent between 118 and 142 dB SPL, and HF4 = 88.6 
percent between 100 and 130 dB SPL. These values may be derived from 
the information in Tables 6.4-8 through 6.4-12 in the Navy's 
rulemaking/LOA application (though they were provided directly to NMFS 
upon request). Based on this information, the majority of the takes by 
Level B behavioral harassment are expected to be low to sometimes 
moderate in nature, but still of a generally shorter duration.
    For all odontocetes, takes from explosives (Level B behavioral 
harassment, TTS, or PTS) comprise a very small fraction (and low 
number) of those caused by exposure to active sonar. For the following 
odontocetes, zero takes from explosives are expected to occur: 
Blainville's beaked whales, Cuvier's beaked whales, bottlenose 
dolphins, false killer whales, killer whales, spinner dolphins, sperm 
whales, rough-toothed dolphins, and pygmy killer whale. For Level B 
behavioral disruption from explosives, 1 to 4 takes are expected to 
occur for all but three of the remaining odontocetes, 0 takes for 
spinner dolphins, and 25 and 64 takes for pygmy and dwarf sperm whales, 
respectively. The instances of PTS expected to occur from explosives 
are 0-1 per species and instances of TTS expected to occur from 
explosives are 0-5 per species, except for pygmy and dwarf sperm 
whales. Because of the lower PTS threshold for HF species, pygmy and 
dwarf sperm whales are expected to have 25 and 64 Level B behavioral 
harassment takes, 8 and 21 PTS takes, and 37 and 100 TTS takes from 
explosives, respectively.
    Because the majority of harassment takes of odontocetes result from 
the sources in the MF1 bin, the vast majority of threshold shift would 
occur at a single frequency within the 1-10 kHz range and, therefore, 
the vast majority of threshold shift caused by Navy sonar sources would 
be at a single frequency within the range of 2-20 kHz. The frequency 
range within which any of the anticipated narrowband threshold shift 
would occur would fall directly within the range of most odontocete 
vocalizations (2-20kHz). For example, the most commonly used hull-
mounted sonar has a frequency around 3.5 kHz, and any associated 
threshold shift would be expected to be at around 7 kHz. However, 
odontocete vocalizations typically span a much wider range than this, 
and alternately, threshold shift from active sonar will often be in a 
narrower band (reflecting the narrower band source that caused it), 
which means that TTS incurred by odontocetes would typically only 
interfere with communication within a portion of their range (if it 
occurred during a time when communication with conspecifics was 
occurring) and, as discussed earlier, it would only be expected to be 
of a short duration and relatively small degree. Odontocete 
echolocation occurs predominantly at frequencies significantly higher 
than 20 kHz, though there may be some small overlap at the lower part 
of their echolocating range for some species, which means that there is 
little likelihood that threshold shift, either temporary or permanent 
would interfere with feeding behaviors. Many of the other critical 
sounds that serve as cues for navigation and prey (e.g., waves, fish, 
invertebrates) occur below a few kHz, which means that detection of 
these signals will not be inhibited by most threshold shift either. The 
low number of takes by threshold shift that might be incurred by 
individuals exposed to explosives would likely be lower frequency (5 
kHz or less) and spanning a wider frequency range, which could slightly 
lower an individual's sensitivity to navigational or prey cues, or a 
small portion of communication calls, for several minutes to hours (if 
temporary) or permanently. There is no reason to think that any of the 
individual odontocetes taken by TTS would incur these types of takes 
over more than one day, or over a few days at most, and therefore they 
are unlikely to incur impacts on reproduction or survival. PTS takes 
from these sources are very low, and while spanning a wider frequency 
band, are still expected to be of a low degree (i.e., low amount of 
hearing sensitivity loss) and unlikely to affect reproduction or 
survival.
    The range of potential behavioral effects of sound exposure on 
marine mammals generally, and odontocetes specifically, has been 
discussed in detail previously. There are behavioral patterns that 
differentiate the likely impacts on odontocetes as compared to 
mysticetes. First, odontocetes echolocate to find prey, which means 
that they actively send out sounds to detect their prey. While there 
are many strategies for hunting, one common pattern, especially for 
deeper diving species, is many repeated deep dives within a bout, and 
multiple bouts within a day, to find and catch prey. As discussed 
above, studies demonstrate that odontocetes may cease their foraging 
dives in response to sound exposure. If enough foraging interruptions 
occur over multiple sequential days, and the individual either does not 
take in the necessary food, or must exert significant effort to find 
necessary food elsewhere, energy budget deficits can occur that could 
potentially result in impacts to reproductive success, such as 
increased cow/calf intervals (the time between successive calving). 
Second, while many mysticetes rely on seasonal migratory patterns that 
position them in a geographic location at a specific time of the year 
to take advantage of ephemeral large abundances of prey (i.e., 
invertebrates or small fish, which they eat by the thousands), 
odontocetes forage more homogeneously on one fish or squid at a time. 
Therefore, if odontocetes are interrupted while feeding, it is often 
possible to find more prey relatively nearby.
Dwarf Sperm Whales and Pygmy Sperm Whales
    In this section, we bring together the discussion of marine mammals 
generally and odontocetes in particular regarding the different types 
and amounts of take that different species will incur, the applicable 
mitigation for each species, and the status of the species to support 
the negligible impact determinations for each. We have previously 
described the unlikelihood of any masking or habitat impacts to any 
marine mammals that would rise to the level of affecting individual 
fitness.
    In Table 52 below for dwarf sperm whales and pygmy sperm whales, we 
indicate the total annual numbers of take by Level A and Level B 
harassment, and a number indicating the instances of total take as a 
percentage of abundance.

[[Page 5887]]



  Table 52--Annual Estimated Takes by Level B Harassment and Level A Harassment for Dwarf Sperm Whales and Pygmy Sperm Whales and Number Indicating the
                                              Instances of Total Take as a Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Instances of indicated types of incidental take  (not all takes          Abundance          Instances of total take
                                       represent separate individuals, especially for disturbance)   --------------------------     as  percentage of
                                    -----------------------------------------------------------------                                   abundance
                                        Level B  harassment      Level A           Total takes                                 -------------------------
              Species               --------------------------  harassment --------------------------               MITT study
                                                              -------------               MITT study   MITT study     area +                  MITT study
                                      Behavioral                             MITT study     area +        area       transit     MITT study     area +
                                     disturbance      TTS          PTS          area       transit                   corridor       area       transit
                                                                                           corridor                                            corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dwarf sperm whale..................        1,353        7,147           50        8,502        8,550       25,594       27,396           33           31
Pygmy sperm whale..................          534        2,876           20        3,412        3,430       10,431       11,169           33           31
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
  transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
  Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
  B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
  Estimated Take of Marine Mammals section.

    As discussed above, the majority of Level B harassment behavioral 
takes of odontocetes, and thereby dwarf and pygmy sperm whales, is 
expected to be in the form of low to occasionally moderate severity of 
a generally shorter duration. As mentioned earlier in this section, we 
anticipate more severe effects from takes when animals are exposed to 
higher received levels or for longer durations. Occasional milder Level 
B behavioral harassment, as is expected here, is unlikely to cause 
long-term consequences for either individual animals or populations, 
even if some smaller subset of the takes are in the form of a longer 
(several hours or a day) and more moderate response.
    We note that dwarf and pygmy sperm whales, as HF-sensitive species, 
have a lower PTS threshold than all other groups and therefore are 
likely to experience larger amounts of TTS and PTS, and NMFS 
accordingly has evaluated and would authorize higher numbers. However, 
Kogia whales are still likely to avoid sound levels that would cause 
higher levels of TTS (greater than 20 dB) or PTS. Therefore, even 
though the number of TTS and PTS takes are higher than for other 
odontocetes, for all of the reasons described above TTS and PTS are not 
expected to impact reproduction or survival of any individual.
    Below we compile and summarize the information that supports our 
preliminary determination that the Navy's activities would not 
adversely affect pygmy and dwarf sperm whales through effects on annual 
rates of recruitment or survival.
    Neither pygmy sperm whales nor dwarf sperm whales are listed under 
the ESA. The stock structure for both pygmy and dwarf sperm whales 
remains uncertain in the western Pacific, and dwarf sperm whales in the 
MITT Study Area have not been assigned to a stock in the current SAR 
(Carretta et al., 2017c; Carretta et al., 2017d). Due to their pelagic 
distribution, small size, and cryptic behavior, pygmy sperm whales and 
dwarf sperm whales are rarely sighted during at-sea surveys and are 
difficult to distinguish between when visually observed in the field. 
There were no species of Kogia sighted during the 2007 shipboard survey 
within the MITT Study Area (Fulling et al., 2011), but three Kogia were 
observed during marine mammal monitoring for Valiant Shield 2007 about 
8 NM east of Guam (Mobley, 2007). In total, during Navy-funded 2010-
2016 small boat surveys in the Mariana Islands, five dwarf sperm whales 
have been encountered on four occasions in a median depth of 
approximately 750 m and at a median distance of approximately 3 km from 
shore (Hill et al., 2017a). The stranding of a pygmy sperm whale in 
1997 (Trianni and Tenorio, 2012) is the only other confirmed occurrence 
of this species in the MITT Study Area.
    No mortality or tissue damage is anticipated or proposed to be 
authorized. Both pygmy and dwarf sperm whales would benefit from the 
procedural mitigation measures described earlier in the Proposed 
Mitigation Measures section. Regarding the magnitude of Level B 
harassment takes (TTS and behavioral disruption), the number of 
estimated total instances of take compared to the abundance is 33 
percent for both dwarf and pygmy sperm whales in the MITT Study Area 
and 31 percent in the MITT Study Area and the transit corridor 
combined, which suggest that some portion of these two species would be 
taken on one to a few days per year (Table 52). As to the severity of 
those individual Level B harassment takes by behavioral disruption, the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB (i.e., of a lower, to occasionally moderate, level and less 
likely to evoke a severe response). As to the severity of TTS takes, 
they are expected to be low-level, of short duration, and mostly not in 
a frequency band that would be expected to interfere with dwarf or 
pygmy sperm whale communication or other important low-frequency cues, 
and the associated lost opportunities and capabilities are not at a 
level that would impact reproduction or survival. Some Level A 
harassment by PTS is anticipated annually (50 and 20 takes for Dwarf 
and pygmy whale, respectively, see Table 52). For these same reasons 
(low level and frequency band), while a small permanent loss of hearing 
sensitivity (PTS) may include some degree of energetic costs for 
compensating or may mean some small loss of opportunities or detection 
capabilities, at the expected scale the estimated Level A harassment 
takes by PTS for dwarf and pygmy sperm whales would be unlikely to 
impact behaviors, opportunities, or detection capabilities to a degree 
that would interfere with reproductive success or survival of any 
individuals, let alone affect annual rates of recruitment or survival. 
For these reasons, in consideration of all of the effects of the Navy's 
activities combined, we have preliminary determined that the proposed 
authorized take will have a negligible impact on pygmy and dwarf sperm 
whales.
Sperm Whale
    In this section, we bring together the discussion of marine mammals 
generally and odontocetes in particular to evaluate the different types 
and amounts of take that sperm whales would incur, the applicable 
mitigation, and the status of the species to support the negligible 
impact determination. We have previously described the unlikelihood of 
any masking or habitat

[[Page 5888]]

impacts to any marine mammals that would rise to the level of affecting 
individual fitness. In Table 53 below for sperm whales, we indicate the 
total annual numbers of take by Level A and Level B harassment, and a 
number indicating the instances of total take as a percentage of 
abundance.

  Table 53--Annual Estimated Takes by Level B Harassment and Level A Harassment for Sperm Whales and Number Indicating the Instances of Total Take as a
                                                             Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Instances of indicated types of incidental take  (not all takes          Abundance          Instances of total take
                                       represent separate individuals, especially for disturbance)   --------------------------     as  percentage of
                                    -----------------------------------------------------------------                                   abundance
                                        Level B  harassment      Level A           Total takes                                 -------------------------
              Species               --------------------------  harassment --------------------------               MITT study
                                                              -------------               MITT study   MITT study     area +                  MITT study
                                      Behavioral                             MITT Study     area +        area       transit     MITT study     area +
                                     disturbance      TTS          PTS          area       transit                   corridor       area       transit
                                                                                           corridor                                            corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale........................          192           11            0          189          203          705        1,635           27           12
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
  transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
  Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
  B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
  Estimated Take of Marine Mammals section.

    The stock structure for sperm whales remains uncertain in the 
Pacific (Mesnick et al., 2011; Mizroch and Rice, 2013; NMFS, 2015a), 
and sperm whales in the MITT Study Area have not been assigned to a 
stock in the current Pacific SAR (Carretta et al., 2017b; Carretta et 
al., 2017c). Sperm whales have been routinely sighted in the MITT Study 
Area and detected in acoustic monitoring records. Acoustic recordings 
in August 2013 at Pagan Island indicated the presence of sperm whales 
within 20 NM of the island (Tetra Tech Inc., 2014). Although it has 
been reported that sperm whales are generally found far offshore in 
deep water (Mizroch and Rice, 2013), sightings in the MITT Study Area 
have included animals close to shore in relatively shallow water as 
well as in areas near steep bathymetric relief (Fulling et al., 2011; 
Hill et al., 2017a; Uyeyama, 2014). A total of 23 sperm whale sightings 
and 93 acoustic encounters were made during the 2007 survey in water 
depths between approximately 400 and 1,000 m depth (Fulling et al., 
2011; Yack et al., 2016). During the Navy-funded 2010-2016 small boat 
surveys in the Mariana Islands, six sperm whales were encountered on 
three occasions in a median depth of approximately 1,200 m and median 
approximate distance from shore of 12 km (Hill et al., 2017a). 
Vocalizations classified as sperm whales were also detected on 20 
occasions to the east and south of Guam by passive acoustic recorders 
during an underwater glider survey in 2014 (Klinck et al., 2016b).
    Below we compile and summarize the information that supports our 
preliminary determination that the Navy's activities would not 
adversely affect sperm whales through effects on annual rates of 
recruitment or survival.
    The sperm whale is listed as endangered under the ESA. No mortality 
or Level A harassment is anticipated or proposed to be authorized. 
Sperm whales would benefit from the procedural mitigation measures 
described earlier in the Proposed Mitigation Measures section. 
Regarding the magnitude of Level B harassment takes (TTS and behavioral 
disruption), the number of estimated total instances of take compared 
to the abundance is 27 percent in the MITT Study Area and 12 percent in 
the MITT Study Area and transit corridor combined (Table 53), which 
suggests that some portion of the sperm whales in the MITT Study Area 
would be taken on one to a few days per year. Regarding the severity of 
those individual Level B harassment takes by behavioral disruption, the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB (i.e., of a lower, to occasionally moderate, level and less 
likely to evoke a severe response). Regarding the severity of TTS 
takes, they are expected to be low-level, of short duration, and mostly 
not in a frequency band that would be expected to interfere with 
important low-frequency cues. While the narrowband/single frequency 
threshold shift incurred may overlap with parts of the frequency range 
that sperm whales use for communication, any associated lost 
opportunities and capabilities would not be at a level that would 
impact reproduction or survival. Any individual whale is likely to be 
disturbed at a low-moderate level, with the taken individuals likely 
exposed on one day. This low magnitude and severity of harassment 
effects is not expected to result in impacts on individual reproduction 
or survival. For these reasons, we have preliminarily determined, in 
consideration of all of the effects of the Navy's activities combined, 
that the proposed authorized take would have a negligible impact on 
sperm whales.
Beaked Whales
    In this section, we build on the broader odontocete discussion 
above (i.e., that information applies to beaked whales as well), except 
where we offer alternative information about the received levels for 
beaked whale Level B behavioral harassment. We bring together the 
discussion of the different types and amounts of take that different 
species will incur, the applicable mitigation for each species, and the 
status of each species to support the negligible impact determination 
for each species.
    We have previously described the unlikelihood of any masking or 
habitat impacts to any groups that would rise to the level of affecting 
individual fitness. The discussion below focuses on additional 
information that is specific to beaked whales (in addition to the 
general information on odontocetes provided above, which is relevant to 
these species) to support the conclusions for each species.
    In Table 54 below for beaked whales, we indicate the total annual 
numbers of take by Level A and Level B harassment, and a number 
indicating the instances of total take as a percentage of abundance.

[[Page 5889]]



 Table 54--Annual Estimated Takes by Level B Harassment and Level A Harassment for Beaked Whales and Number Indicating the Instances of Total Take as a
                                                             Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Instances of indicated types of incidental take (not all  takes          Abundance          Instances of total take
                                       represent separate individuals, especially for  disturbance)  --------------------------     as percentage  of
                                    -----------------------------------------------------------------                                   abundance
                                        Level B  Harassment      Level A           Total Takes                                 -------------------------
              Species               --------------------------  harassment --------------------------               MITT study
                                                              -------------               MITT study   MITT study     area +                  MITT study
                                      Behavioral                             MITT study     area +        area       transit     MITT study     area +
                                     disturbance      TTS          PTS          area       transit                   corridor       area       transit
                                                                                           corridor                                            corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blainville's beaked whale..........        1,691           27            0        1,698        1,719        3,083        3,376           55           51
Cuvier's beaked whale..............          642            4            0          534          647        1,075        2,642           50           24
Ginkgo-toothed beaked whale........        3,660           65            0        3,662        3,725        6,775        7,567           54           49
Longman's beaked whale.............        5,959          107            0        6,056        6,066       11,148       11,253           54           54
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
  transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
  Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
  B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
  Estimated Take of Marine Mammals section.

    This first paragraph provides specific information that is in lieu 
of the parallel information provided for odontocetes as a whole. The 
majority of takes by harassment of beaked whales in the MITT Study Area 
are caused by sources from the MF1 active sonar bin (which includes 
hull-mounted sonar) because they are high level narrowband sources that 
fall within the 1-10 kHz range, which overlap a more sensitive portion 
(though not the most sensitive) of the MF hearing range. Also, of the 
sources expected to result in take, they are used in a large portion of 
exercises (see Table 1.5-1 in the Navy's rulemaking/LOA application). 
Most of the takes (96 percent) from the MF1 bin in the MITT Study Area 
would result from received levels between 148 and 160 dB SPL. For the 
remaining active sonar bin types, the percentages are as follows: LF4 = 
99 percent between 124 and 136 dB SPL, MF4 = 98 percent between 130 and 
148 dB SPL, MF5 = 97 percent between 100 and 142 dB SPL, and HF4 = 95 
percent between 100 and 148 dB SPL. These values may be derived from 
the information in Tables 6.4-8 through 6.4-12 in the Navy's 
rulemaking/LOA application (though they were provided directly to NMFS 
upon request). Given the levels they are exposed to and their 
sensitivity, some responses would be of a lower severity, but many 
would likely be considered moderate.
    Research has shown that beaked whales are especially sensitive to 
the presence of human activity (Pirotta et al., 2012; Tyack et al., 
2011) and therefore have been assigned a lower harassment threshold, 
with lower received levels resulting in a higher percentage of 
individuals being harassed and a more distant distance cutoff (50 km 
for high source level, 25 km for moderate source level).
    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). 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, although few definitive causal relationships 
between MFAS use and strandings have been documented (see Potential 
Effects of Specified Activities on Marine Mammals and their Habitat 
section).
    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. 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; McCarthy et al., 2011; Moretti et al., 2009, 2010; 
Tyack et al., 2010, 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 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 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

[[Page 5890]]

area where anthropogenic sound is present (De Ruiter et al., 2013; 
Manzano-Roth et al., 2013; Moretti et al., 2014; Tyack et al., 2011). 
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 
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. More than eight years 
of passive acoustic monitoring on the Navy's instrumented range west of 
San Clemente Island documented no significant changes in annual and 
monthly beaked whale echolocation clicks, with the exception of 
repeated fall declines likely driven by natural beaked whale life 
history functions (DiMarzio et al., 2018). Finally, results from 
passive acoustic monitoring estimated that regional Cuvier's beaked 
whale densities were higher than indicated by the NMFS' broad scale 
visual surveys for the U.S. west coast (Hildebrand and McDonald, 2009).
    Below we compile and summarize the information that supports our 
preliminary determination that the Navy's activities would not 
adversely affect beaked whales through effects on annual rates of 
recruitment or survival.
    These beaked whale species are not listed as endangered or 
threatened species under the ESA. No mortality or Level A harassment is 
expected or proposed for authorization. All of the beaked whales 
species discussed in this section would benefit from the procedural 
mitigation measures described earlier in the Proposed Mitigation 
Measures section. Regarding the magnitude of Level B harassment takes 
(TTS and behavioral disruption), the number of estimated instances of 
take compared to the abundance is 50 to 55 percent in the MITT Study 
Area and 24 to 54 percent in the MITT Study Area and transit corridor 
combined (Table 54). This information suggests that up to half of the 
individuals of these species could be impacted, if each were taken only 
one day per year, though the more likely scenario is that a smaller 
portion than that would be taken, and a subset of them would be taken 
on a few days. Regarding the severity of those individual Level B 
harassment takes by behavioral disruption, the duration of any exposure 
is expected to be between minutes and hours (i.e., relatively short) 
and the received sound levels largely below 160 dB, though with beaked 
whales, which are considered somewhat more sensitive, this could mean 
that some individuals will leave preferred habitat for a day (i.e., 
moderate level takes). However, while interrupted feeding bouts are a 
known response and concern for odontocetes, we also know that there are 
often viable alternative habitat options nearby. Regarding the severity 
of TTS takes, they are expected to be low-level, of short duration, and 
mostly not in a frequency band that would be expected to interfere with 
beaked whale communication or other important low-frequency cues, and 
that the associated lost opportunities and capabilities are not at a 
level that would impact reproduction or survival.
    As mentioned earlier in the odontocete overview, we anticipate more 
severe effects from takes when animals are exposed to higher received 
levels or sequential days of impacts. Occasional instances of take by 
Level B behavioral harassment of a low to moderate severity are 
unlikely to affect reproduction or survival. Here, some small number of 
takes by Level B behavioral harassment could be in the form of a longer 
(several hours or a day) and more moderate response, and/or some small 
number could be taken over several days, but not at a level that would 
impact reproduction or survival.
    This low magnitude and low to moderate severity of harassment 
effects is not expected to result in impacts on individual reproduction 
or survival. For these reasons, we have preliminarily determined, in 
consideration of all of the effects of the Navy's activities combined, 
that the proposed authorized take would have a negligible impact on 
beaked whales.
Small Whales and Dolphins
    This section builds on the broader discussion above and compiles 
the discussion of the different types and amounts of take that 
different small whale and dolphin species may incur, the applicable 
mitigation for dolphin and small whale species, and the status of the 
species to support the negligible impact determinations. We have 
previously described the unlikelihood of any masking or habitat impacts 
to any groups that would rise to the level of affecting individual 
fitness. The discussion below focuses on additional information that is 
specific to these species (in addition to the general information on 
odontocetes provided above, which is relevant to these species) to 
support the conclusions for each species.
    In Table 55 below for dolphins and small whales, we indicate the 
total annual numbers of take by Level A and Level B harassment, and a 
number indicating the instances of total take as a percentage of 
abundance.

Table 55--Annual Estimated Takes by Level B Harassment and Level A Harassment for Dolphins and Small Whales and Number Indicating the Instances of Total
                                                        Take as a Percentage of Species Abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                      Instances of indicated types of incidental take (not all takes          Abundance          Instances of total take
                                       represent separate individuals, especially for disturbance)   --------------------------     as percentage of
                                    -----------------------------------------------------------------                                   abundance
                                        Level B harassment       Level A           Total takes                                 -------------------------
              Species               --------------------------  harassment --------------------------               MITT study
                                                              -------------               MITT study   MITT study     area +                  MITT study
                                      Behavioral                             MITT study     area +        area       transit     MITT study     area +
                                     disturbance      TTS          PTS          area       transit                   corridor       area       transit
                                                                                           corridor                                            corridor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bottlenose dolphin.................          116           21            0          132          137          753        1,075           17           13
False killer whale.................          641          121            0          759          762        3,979        4,218           19           18
Fraser's dolphin...................       11,327        1,952            1       13,261       13,280       75,420       76,476           18           17
Killer whale.......................           36            8            0           44           44          215          253           20           17
Melon-headed whale.................        2,306          508            0        2,798        2,814       15,342       16,461           18           17
Pantropical spotted dolphin........       12,078        2,818            1       14,820       14,897       81,013       85,755           18           17

[[Page 5891]]

 
Pygmy killer whale.................           87           17            0          103          104          502          527           21           20
Risso's dolphin....................        2,650          519            0        3,166        3,169       16,991       17,184           19           18
Rough-toothed dolphin..............          161           36            0          185          197        1,040        1,815           18           11
Short-finned pilot whale...........          987          177            0        1,150        1,164        5,700        6,583           20           18
Spinner dolphin....................        1,185          229            1        1,404        1,415        2,975        3,759           47           38
Striped dolphin....................        3,256          751            0        3,956        4,007       22,081       24,528           18           16
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Abundance was calculated using the following formulas: Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area
  transit corridor = Abundance in the transit corridor and Density from the Technical Report in animals/km\2\ x spatial extent of the MITT Study Area =
  Abundance in the MITT Study. In addition, the total annual takes described here may be off by a digit due to rounding. This occurred here as the Level
  B harassment takes are broken down further into Behavioral Disturbance and TTS compared to the Level B harassment takes presented as one number in the
  Estimated Take of Marine Mammals section.

    As described above, the large majority of Level B behavioral 
harassment to odontocetes, and thereby dolphins and small whales, from 
hull-mounted sonar (MF1) in the MITT Study Area would result from 
received levels between 160 and 172 dB SPL. Therefore, the majority of 
Level B harassment takes are expected to be in the form of low to 
occasionally moderate responses of a generally shorter duration. As 
mentioned earlier in this section, we anticipate more severe effects 
from takes when animals are exposed to higher received levels. 
Occasional milder occurrences of Level B behavioral harassment are 
unlikely to cause long-term consequences for individual animals or 
populations that have any effect on reproduction or survival.
    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. Some dolphin species (the more 
surface-dwelling taxa--typically those with ``dolphin'' in the common 
name, such as bottlenose dolphins, spotted dolphins, spinner dolphins, 
rough-toothed dolphins, etc., but not Risso's dolphin), especially 
those residing in more industrialized or busy areas, have demonstrated 
more tolerance for disturbance and loud sounds and many of these 
species are known to approach vessels to bow-ride. These species are 
often considered generally less sensitive to disturbance. Dolphins and 
small whales that reside in deeper waters and generally have fewer 
interactions with human activities are more likely to demonstrate more 
typical avoidance reactions and foraging interruptions as described 
above in the odontocete overview.
    All the dolphin and small whale species discussed in this section 
would benefit from the procedural mitigation measures described earlier 
in the Proposed Mitigation Measures section. Additionally, the Agat Bay 
Nearshore Geographic Mitigation Area will provide protection for 
spinner dolphins as the Navy will not use in-water explosives or MF1 
ship hull-mounted mid-frequency active sonar in this area. High use 
areas for spinner dolphins including Agat Bay are where animals 
congregate during the day to rest (Amesbury et al., 2001; Eldredge, 
1991). Behavioral disruptions during resting periods can adversely 
impact health and energetic budgets by not allowing animals to get the 
needed rest and/or by creating the need to travel and expend additional 
energy to find other suitable resting areas. Avoiding sonar and 
explosives in this area reduces the likelihood of impacts that would 
affect reproduction and survival.
    Below we compile and summarize the information that supports our 
preliminary determination that the Navy's activities would not 
adversely affect dolphins and small whales through effects on annual 
rates of recruitment or survival.
    None of the small whale and dolphin species are listed as 
endangered or threatened species under the ESA. No mortality or Level A 
harassment is anticipated or proposed to be authorized, with the 
exception of one Level A harassment take by PTS each for spinner 
dolphin, pantropical spotted dolphin, and Fraser's dolphin. No tissue 
damage is anticipated or proposed to be authorized for any species. 
Regarding the magnitude of Level B harassment takes (TTS and behavioral 
disruption), the number of estimated total instances of take compared 
to the abundance is 47 percent for spinner dolphins and 17 to 21 
percent for the remaining dolphins and small whales in the MITT Study 
Area, which suggests that some portion of these species would be taken 
on one to a few days per year. Additionally, the number of estimated 
total instances of take compared to the abundance is 38 percent for 
spinner dolphins and 20 percent or less for the remaining dolphins and 
small whales in the MITT Study and transit corridor combined, which 
would also suggest that some portion of these species would be taken on 
one to a few days per year (Table 55). As to the severity of those 
individual Level B harassment takes by behavioral disruption, the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB (i.e., of a lower, to occasionally moderate, level and less 
likely to evoke a severe response). As to the severity of TTS takes, 
they are expected to be low-level, of short duration, and mostly not in 
a frequency band that would be expected to interfere with communication 
or other important low-frequency cues. The associated lost 
opportunities and capabilities are not at a level that would impact 
reproduction or survival. Any individual dolphin or small whale is 
likely to be disturbed at a low-moderate level, with the taken 
individuals likely exposed on one to a few days. This low magnitude and 
severity of harassment effects is not expected to result in impacts on 
individual reproduction or survival. Three species (spinner dolphin, 
Fraser's dolphin, and pantropical spotted

[[Page 5892]]

dolphin) could be taken by one PTS annually of likely low severity. A 
small permanent loss of hearing sensitivity (PTS) may include some 
degree of energetic costs for compensating or may mean some small loss 
of opportunities or detection capabilities, but at the expected scale 
the estimated Level A harassment takes by PTS for spinner dolphin, 
Fraser's dolphin, and pantropical spotted dolphin would be unlikely to 
impact behaviors, opportunities, or detection capabilities to a degree 
that would interfere with reproductive success or survival of any 
individuals, let alone affect annual rates of recruitment or survival. 
For these reasons, we have preliminarily determined, in consideration 
of all of the effects of the Navy's activities combined, that the 
proposed authorized take would have a negligible impact on small whales 
and dolphins.
    Altogether, only a small portion of any odontocete population is 
anticipated to be impacted, and any individual whale or dolphin is 
likely to be disturbed at a low-moderate level, with the taken 
individuals likely exposed on one day or a few days. This low magnitude 
and severity of harassment effects is unlikely to result in impacts on 
individual reproduction or survival, much less annual rates of 
recruitment or survival of any of the species. For these reasons, we 
have preliminarily determined, in consideration of all of the effects 
of the Navy's activities combined, that the proposed authorized take 
would have a negligible impact on all of the odontocete species.

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.

Subsistence Harvest of Marine Mammals

    There are no subsistence uses or harvest of marine mammals in the 
geographic area affected by the specified activities. Therefore, NMFS 
has preliminarily determined that the total taking affecting species 
would not have an unmitigable adverse impact on the availability of the 
species for taking for subsistence purposes.

Classifications

Endangered Species Act

    There are five marine mammal species under NMFS jurisdiction that 
are listed as endangered or threatened under the ESA with confirmed or 
possible occurrence in the MITT Study Area: Blue whale, fin whale, 
humpback whale, sei whale, and sperm whale. There is no ESA-designated 
critical habitat for any species in the MITT Study Area. The Navy will 
consult with NMFS pursuant to section 7 of the ESA for MITT Study Area 
activities. NMFS will also consult internally on the issuance of the 
regulations and LOA under section 101(a)(5)(A) of the MMPA. NMFS' 
Permits and Conservation Division is currently discussing the Navy 
rulemaking/LOA application with NMFS' ESA Interagency Cooperation 
Division.

National Marine Sanctuaries Act

    There are no national marine sanctuaries in the MITT Study Area. 
Therefore, no consultation under the National Marine Sanctuaries Act is 
required.

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 evaluate our proposed actions and alternatives with respect 
to potential impacts on the human environment. Accordingly, NMFS plans 
to adopt the Navy's EIS/OEIS for the MITT 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 an LOA under the MMPA. NMFS is a cooperating agency on 
the 2019 MITT DEIS/OEIS and has worked extensively with the Navy in 
developing the document. The 2019 MITT DEIS/OEIS was made available for 
public comment at https://www.MITT-eis.com, January 2019. We will review 
all comments submitted in response to this notice prior to concluding 
our NEPA process or making a final decision on the MMPA rule and LOA 
request.

Regulatory Flexibility Act

    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 that 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 and recordkeeping requirements, 
Seafood, Sonar, Transportation.

    Dated: January 9, 2020.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.

    For reasons set forth in the preamble, 50 CFR part 218 is proposed 
to be amended as follows:

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., unless otherwise noted.

0
2. Revise subpart J to part 218 to read as follows:
Subpart J--Taking and Importing Marine Mammals; U.S. Navy's Mariana 
Islands Training and Testing (MITT)
Sec.
218.90 Specified activity and geographical region.
218.91 Effective dates.
218.92 Permissible methods of taking.

[[Page 5893]]

218.93 Prohibitions.
218.94 Mitigation requirements.
218.95 Requirements for monitoring and reporting.
218.96 Letters of Authorization.
218.97 Renewals and modifications of Letters of Authorization.
218.98 [Reserved]

Subpart J--Taking and Importing Marine Mammals; U.S. Navy's Mariana 
Islands Training and Testing (MITT)


Sec.  218.90   Specified activity and geographical region.

    (a) Regulations in this subpart apply only to the U.S. Navy (Navy) 
for the taking of marine mammals that occurs in the area described in 
paragraph (b) of this section and that occurs incidental to the 
activities listed in paragraph (c) of this section.
    (b)(1) The taking of marine mammals by the Navy under this subpart 
may be authorized in a Letter of Authorization (LOA) only if it occurs 
within the Mariana Islands Training and Testing (MITT) Study Area. The 
MITT Study Area is comprised of three components:
    (i) The Mariana Islands Range Complex (MIRC);
    (ii) Additional areas on the high seas; and
    (iii) A transit corridor between the MIRC and the Hawaii Range 
Complex (HRC).
    (2) The MIRC includes the waters south of Guam to north of Pagan 
(Commonwealth of the Northern Mariana Islands (CNMI)), and from the 
Pacific Ocean east of the Mariana Islands to the Philippine Sea to the 
west, encompassing 501,873 square nautical miles (NM\2\) of open ocean. 
For the additional areas of the high seas, this includes the area to 
the north of the MIRC that is within the U.S. Exclusive Economic Zone 
(EEZ) of the CNMI and the areas to the west of the MIRC. The transit 
corridor is outside the geographic boundaries of the MIRC and 
represents a great circle route (i.e., the shortest distance) across 
the high seas for Navy ships transiting between the MIRC and the HRC. 
Additionally, the MITT Study Area includes pierside locations in the 
Apra Harbor Naval Complex.
    (c) The taking of marine mammals by the Navy is only authorized if 
it occurs incidental to the Navy conducting training and testing 
activities, including:
    (1) Training. (i) Amphibious warfare;
    (ii) Anti-submarine warfare;
    (iii) Mine warfare;
    (vi) Surface warfare; and
    (vii) Other training activities.
    (2) Testing. (i) Naval Air Systems Command Testing Activities;
    (ii) Naval Sea System Command Testing Activities; and
    (iii) Office of Naval Research Testing Activities.


Sec.  218.91   Effective dates.

    Regulations in this subpart are effective from [DATE OF PUBLICATION 
OF FINAL RULE IN THE Federal Register] through August 3, 2027.


Sec.  218.92   Permissible methods of taking.

    (a) Under an LOA issued pursuant to Sec. Sec.  216.106 of this 
chapter and 218.96, the Holder of the LOA (hereinafter ``Navy'') may 
incidentally, but not intentionally, take marine mammals within the 
area described in Sec.  218.90(b) by Level A harassment and Level B 
harassment associated with the use of active sonar and other acoustic 
sources and explosives, provided the activity is in compliance with all 
terms, conditions, and requirements of these regulations in this 
subpart and the applicable LOAs.
    (b) The incidental take of marine mammals by the activities listed 
in Sec.  218.90(c) is limited to the following species:

                        Table 1 to Sec.   218.92
------------------------------------------------------------------------
                  Species                          Scientific Name
------------------------------------------------------------------------
Blue whale................................  Balaenoptera musculus
Bryde's whale.............................  Balaenoptera edeni
Fin whale.................................  Balaenoptera physalus
Humpback whale............................  Megaptera novaeangliae
Minke whale...............................  Balaenoptera acutorostrata
Omura's whale.............................  Balaenoptera omurai
Sei whale.................................  Balaenoptera borealis
Blainville's beaked whale.................  Mesoplodon densirostris
Common bottlenose dolphin.................  Tursiops truncatus
Cuvier's beaked whale.....................  Ziphius cavirostris
Dwarf sperm whale.........................  Kogia sima
False killer whale........................  Pseudorca crassidens
Fraser's dolphin..........................  Lagenodelphis hosei
Ginkgo-toothed beaked whale...............  Mesoplodon ginkgodens
Killer whale..............................  Orcinus orca
Longman's beaked whale....................  Indopacetus pacificus
Melon-headed whale........................  Peponocephala electra
Pantropical spotted dolphin...............  Stenella attenuata
Pygmy killer whale........................  Feresa attenuata
Pygmy sperm whale.........................  Kogia breviceps
Risso's dolphin...........................  Grampus griseus
Rough-toothed dolphin.....................  Steno bredanensis
Short-finned pilot whale..................  Globicephala macrorhynchus
Sperm whale...............................  Physeter macrocephalus
Spinner dolphin...........................  Stenella longirostris
Striped dolphin...........................  Stenella coeruleoalba
------------------------------------------------------------------------

Sec.  218.93   Prohibitions.

    Notwithstanding incidental takings contemplated in Sec.  218.92(a) 
and authorized by LOAs issued under Sec. Sec.  216.106 of this chapter 
and 218.96, no person in connection with the activities listed in Sec.  
218.90(c) may:
    (a) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or an LOA issued under Sec. Sec.  216.106 
of this chapter and 218.96;
    (b) Take any marine mammal not specified in Sec.  218.92(b);
    (c) Take any marine mammal specified in Sec.  218.92(b) in any 
manner other than as specified in the LOAs; or
    (d) Take a marine mammal specified in Sec.  218.92(b) if NMFS 
determines such taking results in more than a negligible impact on the 
species or stocks of such marine mammal.


Sec.  218.94   Mitigation requirements.

    When conducting the activities identified in Sec.  218.90(c), the 
mitigation measures contained in any LOAs issued under Sec. Sec.  
216.106 of this chapter and 218.96 must be implemented. These 
mitigation measures include, but are not limited to:
    (a) Procedural mitigation. Procedural mitigation is mitigation that 
the Navy must implement whenever and wherever an applicable training or 
testing activity takes place within the MITT Study Area for each 
applicable activity category or stressor category and includes acoustic 
stressors (i.e., active sonar and other transducers, 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 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; and non-explosive bombs and mine 
shapes).
    (1) Environmental awareness and education. Appropriate Navy 
personnel (including civilian personnel) involved in mitigation and 
training or testing activity reporting under the specified activities 
will complete one or more modules of the U.S Navy Afloat Environmental 
Compliance Training Series, as identified in their career path training 
plan. Modules include: Introduction to the U.S. Navy Afloat 
Environmental Compliance Training Series, Marine Species Awareness 
Training; U.S. Navy Protective Measures Assessment Protocol; and U.S. 
Navy Sonar Positional Reporting System and Marine Mammal Incident 
Reporting.
    (2) Active sonar. Active sonar includes low-frequency active sonar, 
mid-frequency active sonar, and high-frequency active sonar. For 
vessel-based 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 
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).

[[Page 5894]]

    (i) Number of Lookouts and observation platform--(A) Hull-mounted 
sources. One Lookout for platforms with space or manning restrictions 
while underway (at the forward part of a small boat or ship) and 
platforms using active sonar while moored or at anchor (including 
pierside); and two Lookouts for platforms without space or manning 
restrictions while underway (at the forward part of the ship).
    (B) Sources that are not hull-mounted sources. One Lookout on the 
ship or aircraft conducting the activity.
    (ii) Mitigation zone and requirements. (A) During the activity, at 
1,000 yards (yd) Navy personnel must power down 6 decibels (dB), at 500 
yd Navy personnel must power down an additional 4 dB (for a total of 10 
dB), and at 200 yd Navy personnel must shut down for low-frequency 
active sonar >=200 dB and hull-mounted mid-frequency active sonar; or 
at 200 yd Navy personnel must shut down for low-frequency active sonar 
<200 dB, mid-frequency active sonar sources that are not hull-mounted, 
and high-frequency active sonar.
    (B) Prior to the start of the activity (e.g., when maneuvering on 
station), Navy personnel must observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must relocate 
or delay the start of active sonar transmission.
    (C) During the activity for low-frequency active sonar at or above 
200 dB and hull-mounted mid-frequency active sonar, Navy personnel must 
observe the mitigation zone for marine mammals and power down active 
sonar transmission by 6 dB if marine mammals are observed within 1,000 
yd of the sonar source; power down by an additional 4 dB (for a total 
of 10 dB total) if marine mammals are observed within 500 yd of the 
sonar source; and cease transmission if marine mammals are observed 
within 200 yd of the sonar source.
    (D) During the activity for low-frequency active sonar below 200 
dB, mid-frequency active sonar sources that are not hull mounted, and 
high-frequency active sonar, Navy personnel must observe the mitigation 
zone for marine mammals and cease active sonar transmission if marine 
mammals are observed within 200 yd of the sonar source.
    (E) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing or powering up active sonar transmission) until 
one of the following 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 minutes (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 where a 
dolphin(s) is observed in the mitigation zone, the Lookout concludes 
that the dolphin(s) is deliberately closing in on the ship to ride the 
ship's bow wave, and is therefore out of the main transmission axis of 
the sonar (and there are no other marine mammal sightings within the 
mitigation zone).
    (3) Weapons firing noise. Weapons firing noise associated with 
large-caliber gunnery activities.
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on the ship conducting the firing. Depending on the 
activity, the Lookout could be the same as the one provided for under 
``Explosive medium-caliber and large-caliber projectiles'' or under 
``Small-, medium-, and large-caliber non-explosive practice munitions'' 
in paragraphs (a)(8)(i) and (a)(17)(i) of this section.
    (ii) Mitigation zone and requirements. (A) Thirty degrees on either 
side of the firing line out to 70 yd from the muzzle of the weapon 
being fired.
    (B) Prior to the start of the activity, Navy personnel must observe 
the mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must relocate or delay the start of weapons firing.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease weapons firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing weapons firing) until one of the following 
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 must be positioned in an aircraft or on a small 
boat. If additional platforms are participating in the activity, Navy 
personnel positioned in those assets (e.g., safety observers, 
evaluators) must support observing the mitigation zone for applicable 
biological resources while performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 600 yd around an 
explosive sonobuoy.
    (B) Prior to the initial start of the activity (e.g., during 
deployment of a sonobuoy field, which typically lasts 20-30 min), Navy 
personnel must conduct passive acoustic monitoring for marine mammals 
and use information from detections to assist visual observations. Navy 
personnel also must visually observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must relocate 
or delay the start of sonobuoy or source/receiver pair detonations.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease sonobuoy or source/receiver pair detonations.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing detonations) until one of the following 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 (e.g., helicopter), or 30 min when the activity involves 
aircraft that are not typically fuel constrained.
    (E) After completion of the activity (e.g., prior to maneuvering 
off station), when practical (e.g., when platforms are not constrained 
by fuel restrictions or mission-essential follow-on commitments), Navy 
personnel must

[[Page 5895]]

observe for marine mammals in the vicinity of where detonations 
occurred; if any injured or dead marine mammals are observed, Navy 
personnel must follow established incident reporting procedures. If 
additional platforms are supporting this activity (e.g., providing 
range clearance), these Navy assets must assist in the visual 
observation of the area where detonations occurred.
    (7) Explosive torpedoes--(i) Number of Lookouts and observation 
platform. One Lookout positioned in an aircraft. If additional 
platforms are participating in the activity, Navy personnel positioned 
in those assets (e.g., safety observers, evaluators) must support 
observing the mitigation zone for applicable biological resources while 
performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 2,100 yd around the 
intended impact location.
    (B) Prior to the initial start of the activity (e.g., during 
deployment of the target), Navy personnel must conduct passive acoustic 
monitoring for marine mammals and use the information from detections 
to assist visual observations. Navy personnel also must visually 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must relocate or delay the start of firing.
    (C) During the activity, Navy personnel must observe for marine 
mammals. If marine mammals are observed, Navy personnel must cease 
firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following 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.
    (E) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets must assist in the visual 
observation of the area where detonations occurred.
    (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 must 
be 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)(3)(i) of this section. If additional platforms 
are participating in the activity, Navy personnel positioned in those 
assets (e.g., safety observers, evaluators) must support observing the 
mitigation zone for applicable biological resources while performing 
their regular duties.
    (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.
    (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), Navy personnel must observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must relocate 
or delay the start of firing.
    (E) During the activity, Navy personnel must observe for marine 
mammals; if marine mammals are observed, Navy personnel must cease 
firing.
    (F) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following 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 
intended impact location has transited a distance equal to double that 
of the mitigation zone size beyond the location of the last sighting.
    (G) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must, when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets must assist in the visual 
observation of the area where detonations occurred.
    (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 must 
be positioned in an aircraft. If additional platforms are participating 
in the activity, Navy personnel positioned in those assets (e.g., 
safety observers, evaluators) must support observing the mitigation 
zone for applicable biological resources while performing their regular 
duties.
    (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.
    (B) 2,000 yd around the intended impact location for missiles with 
21-500 lb net explosive weight.
    (C) Prior to the initial start of the activity (e.g., during a fly-
over of the mitigation zone), Navy personnel must observe the 
mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must relocate or delay the start of firing.
    (D) During the activity, Navy personnel must observe for marine 
mammals; if marine mammals are observed, Navy personnel must cease 
firing.
    (E) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing

[[Page 5896]]

firing) until one of the following 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.
    (F) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must, when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets will assist in the visual 
observation of the area where detonations occurred.
    (10) Explosive bombs--(i) Number of Lookouts and observation 
platform. One Lookout must be positioned in an aircraft conducting the 
activity. If additional platforms are participating in the activity, 
Navy personnel positioned in those assets (e.g., safety observers, 
evaluators) must support observing the mitigation zone for applicable 
biological resources while performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 2,500 yd around the 
intended target.
    (B) Prior to the initial start of the activity (e.g., when arriving 
on station), Navy personnel must observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must relocate 
or delay the start of bomb deployment.
    (C) During the activity (e.g., during target approach), Navy 
personnel must observe the mitigation zone for marine mammals; if 
marine mammals are observed, Navy personnel must cease bomb deployment.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing bomb deployment) until one of the following 
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.
    (E) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must, when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets must assist in the visual 
observation of the area where detonations occurred.
    (11) Sinking exercises--(i) Number of Lookouts and observation 
platform. Two Lookouts (one must be positioned in an aircraft and one 
must be positioned on a vessel). If additional platforms are 
participating in the activity, Navy personnel positioned in those 
assets (e.g., safety observers, evaluators) must support observing the 
mitigation zone for applicable biological resources while performing 
their regular duties.
    (ii) Mitigation zone and requirements. (A) 2.5 NM around the target 
ship hulk.
    (B) Prior to the initial start of the activity (90 min prior to the 
first firing), Navy personnel must conduct aerial observations of the 
mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must delay the start of firing.
    (C) During the activity, Navy personnel must conduct passive 
acoustic monitoring for marine mammals and use the information from 
detections to assist visual observations. Navy personnel must visually 
observe the mitigation zone for marine mammals from the vessel; if 
marine mammals are observed, Navy personnel must cease firing. 
Immediately after any planned or unplanned breaks in weapons firing of 
longer than two hours, Navy personnel must observe the mitigation zone 
for marine mammals from the aircraft and vessel; if marine mammals are 
observed, Navy personnel must delay recommencement of firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following 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) After completion of the activity (for two hours after sinking 
the vessel or until sunset, whichever comes first), Navy personnel must 
observe for marine mammals in the vicinity of where detonations 
occurred; if any injured or dead marine mammals are observed, Navy 
personnel must follow established incident reporting procedures. If 
additional platforms are supporting this activity (e.g., providing 
range clearance), these Navy assets will assist in the visual 
observation of the area where detonations occurred.
    (12) Explosive mine countermeasure and neutralization activities--
(i) Number of Lookouts and observation platform. (A) One Lookout must 
be positioned on a vessel or in an aircraft.
    (B) If additional platforms are participating in the activity, Navy 
personnel positioned in those assets (e.g., safety observers, 
evaluators) must support observing the mitigation zone for applicable 
biological resources while performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 600 yd around the 
detonation site.
    (B) Prior to the initial 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), Navy 
personnel must observe the mitigation zone for marine mammals; if 
marine mammals are observed, Navy personnel must relocate or delay the 
start of detonations.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease detonations.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing detonations) until one of the following conditions 
has been met: The animal is observed exiting the mitigation zone;

[[Page 5897]]

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 (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), Navy personnel must observe for marine mammals in the 
vicinity of where detonations occurred; if any injured or dead marine 
mammals are observed, Navy personnel must follow established incident 
reporting procedures. If additional platforms are supporting this 
activity (e.g., providing range clearance), these Navy assets must 
assist in the visual observation of the area where detonations 
occurred.
    (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 must be 
on a small boat and one must be 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 must serve as an additional Lookout if 
aircraft are used during the activity, when implementing the larger 
mitigation zone.
    (C) All divers placing the charges on mines will support the 
Lookouts while performing their regular duties and will report 
applicable sightings to their supporting small boat or Range Safety 
Officer.
    (D) If additional platforms are participating in the activity, Navy 
personnel positioned in those assets (e.g., safety observers, 
evaluators) must support observing the mitigation zone for applicable 
biological resources while performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 500 yd around the 
detonation site during activities under positive control using.
    (B) 1,000 yd around the detonation site during all activities using 
time-delay fuses.
    (C) Prior to the initial start of the activity (e.g., when 
maneuvering on station for activities under positive control; 30 min 
for activities using time-delay firing devices), Navy personnel must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must relocate or delay the start of 
detonations or fuse initiation.
    (D) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease detonations or fuse initiation. To the maximum extent 
practicable depending on mission requirements, safety, and 
environmental conditions, Navy personnel must position boats near the 
mid-point of the mitigation zone radius (but outside of the detonation 
plume and human safety zone), must position themselves on opposite 
sides of the detonation location (when two boats are used), and must 
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, 
Navy aircraft must travel in a circular pattern around the detonation 
location to the maximum extent practicable. Navy personnel must not set 
time-delay firing devices to exceed 10 min.
    (E) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted animal to leave the mitigation zone prior to the initial start 
of the activity (by delaying the start) or during the activity (by not 
recommencing detonations) until one of the following 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.
    (F) After completion of an activity, the Navy must observe for 
marine mammals for 30 min. Navy personnel must observe for marine 
mammals in the vicinity of where detonations occurred; if any injured 
or dead marine mammals are observed, Navy personnel must follow 
established incident reporting procedures. If additional platforms are 
supporting this activity (e.g., providing range clearance), these Navy 
assets must assist in the visual observation of the area where 
detonations occurred.
    (14) Maritime security operations--anti-swimmer grenades--(i) 
Number of Lookouts and observation platform. One Lookout must be 
positioned on the small boat conducting the activity. If additional 
platforms are participating in the activity, Navy personnel positioned 
in those assets (e.g., safety observers, evaluators) must support 
observing the mitigation zone for applicable biological resources while 
performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 200 yd around the 
intended detonation location.
    (B) Prior to the initial start of the activity (e.g., when 
maneuvering on station), Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must relocate or delay the start of detonations.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease detonations.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing detonations) until one of the following 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.
    (E) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must, when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets will assist in the visual 
observation of the area where detonations occurred.
    (15) Vessel movement. The mitigation will 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); the vessel is

[[Page 5898]]

operated autonomously; or when impracticable based on mission 
requirements (e.g., during Amphibious Assault and Amphibious Raid 
exercises).
    (i) Number of Lookouts and observation platform. One Lookout must 
be on the vessel that is underway.
    (ii) Mitigation zone and requirements. (A) 500 yd around whales.
    (B) 200 yd around all other marine mammals (except bow-riding 
dolphins).
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must maneuver to maintain distance.
    (iv) Incident reporting procedures. If a marine mammal vessel 
strike occurs, Navy personnel must follow the established incident 
reporting procedures.
    (16) Towed in-water devices. Mitigation applies to devices that are 
towed from a manned surface platform or manned aircraft. The mitigation 
will not be applied if the safety of the towing platform or in-water 
device is threatened.
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on a manned towing platform.
    (ii) Mitigation zone and requirements. (A) 250 yd around marine 
mammals.
    (B) During the activity (i.e., when towing an in-water device), 
Navy personnel must observe the mitigation zone for marine mammals; if 
marine mammals are observed, Navy personnel must maneuver to maintain 
distance.
    (17) 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 must 
be 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)(3)(i) of this section.
    (ii) Mitigation zone and requirements. (A) 200 yd around the 
intended impact location.
    (B) Prior to the start of the activity (e.g., when maneuvering on 
station), Navy personnel must observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must relocate 
or delay the start of firing.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following 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.
    (18) 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 must 
be positioned in an aircraft.
    (ii) Mitigation zone and requirements. (A) 900 yd around the 
intended impact location.
    (B) Prior to the initial start of the activity (e.g., during a fly-
over of the mitigation zone), Navy personnel must observe the 
mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must relocate or delay the start of firing.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting prior to or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following 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.
    (19) 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 must 
be positioned in an aircraft.
    (ii) Mitigation zone and requirements. (A) 1,000 yd around the 
intended target.
    (B) Prior to the initial start of the activity (e.g., when arriving 
on station), Navy personnel must observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must relocate 
or delay the start of bomb deployment or mine laying.
    (C) During the activity (e.g., during approach of the target or 
intended minefield location), Navy personnel must observe the 
mitigation zone for marine mammals and, if marine mammals are observed, 
Navy personnel must cease bomb deployment or mine laying.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting prior to or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing bomb deployment or mine laying) until one of the 
following 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, Navy 
personnel must implement mitigation measures within mitigation areas to 
avoid or reduce potential impacts on marine mammals.
    (1) Mitigation areas for marine mammals off Saipan in MITT Study 
Area for sonar, explosives, and vessel strikes--(i) Mitigation area 
requirements--(A) Marpi Reef Geographic Mitigation Area. (1) Navy 
personnel must not use explosives that could potentially result in 
takes of marine mammals during training and testing.
    (2) The Navy will also report the total hours of MF1 surface ship 
hull-mounted mid-frequency active sonar from December through April 
used in this

[[Page 5899]]

area in its annual training and testing activity reports submitted to 
NMFS.
    (3) Should national security require the use of explosives that 
could potentially result in the take of marine mammals during training 
or testing, Naval units must obtain permission from the appropriate 
designated Command authority prior to commencement of the activity. 
Navy personnel must provide NMFS with advance notification and include 
the information (e.g., explosive usage) in its annual activity reports 
submitted to NMFS.
    (B) Chalan Kanoa Geographic Mitigation Area. (1) Navy personnel 
must not use explosives that could potentially result in takes of 
marine mammals during training and testing.
    (2) The Navy will also report the total hours of MF1 surface ship 
hull-mounted mid-frequency active sonar from December through April 
used in this area in its annual training and testing activity reports 
submitted to NMFS.
    (3) Should national security require the use of explosives that 
could potentially result in the take of marine mammals during training 
or testing, Naval units must obtain permission from the appropriate 
designated Command authority prior to commencement of the activity. 
Navy personnel must provide NMFS with advance notification and include 
the information (e.g., explosive usage) in its annual activity reports 
submitted to NMFS.
    (C) Marpi Reef and Chalan Kanoa Reef Awareness Notification Message 
Area (December-April). (1) Navy personnel must issue a seasonal 
awareness notification message to alert ships and aircraft operating in 
the area to the possible presence of concentrations of large whales, or 
increased concentrations of humpback whales.
    (2) To maintain safety of navigation and to avoid interactions with 
large whales during transits, Navy personnel must 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.
    (3) Platforms must 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) [Reserved]
    (2) Mitigation areas for marine mammals off Guam of the MITT Study 
Area for sonar and explosives--(i) Mitigation area requirements--(A) 
Agat Bay Nearshore Geographic Mitigation Area. (1) Navy personnel must 
not conduct MF1 surface ship hull-mounted mid-frequency active sonar 
year-round.
    (2) Should national security require the use of MF1 surface ship 
hull-mounted mid-frequency active sonar during training and testing 
within the Agat Bay Nearshore Geographic Mitigation Area, Naval units 
must obtain permission from the appropriate designated Command 
authority prior to commencement of the activity. Navy personnel must 
provide NMFS with advance notification and include the information 
(e.g., sonar hours) in its annual activity reports submitted to NMFS.
    (3) Navy personnel must not use in-water explosives year-round.
    (4) Should national security require the use of explosives that 
could potentially result in the take of marine mammals during training 
or testing within the Agat Bay Nearshore Geographic Mitigation Area, 
Naval units must obtain permission from the appropriate designated 
Command authority prior to commencement of the activity. Navy personnel 
must provide NMFS with advance notification and include the information 
(e.g., explosives usage) in its annual activity reports submitted to 
NMFS.
    (B) [Reserved]


Sec.  218.95   Requirements for monitoring and reporting.

    (a) Unauthorized take. Navy personnel must notify NMFS immediately 
(or as soon as operational security considerations allow) if the 
specified activity identified in Sec.  218.90 is thought to have 
resulted in the mortality or serious injury of any marine mammals, or 
in any Level A harassment or Level B harassment take of marine mammals 
not identified in this subpart.
    (b) Monitoring and reporting under the LOA. The Navy must conduct 
all monitoring and reporting required under the LOA, including abiding 
by the MITT Study Area monitoring program. Details on program goals, 
objectives, project selection process, and current projects are 
available at www.navymarinespeciesmonitoring.us.
    (c) Notification of injured, live stranded, or dead marine mammals. 
The Navy must consult the Notification and Reporting Plan, which sets 
out notification, reporting, and other requirements when dead, injured, 
or live stranded marine mammals are detected. The Notification and 
Reporting Plan is available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
    (d) Annual MITT Study Area marine species monitoring report. The 
Navy must submit an annual report of the MITT Study Area monitoring 
describing the implementation and results from the previous calendar 
year. Data collection methods must be standardized across range 
complexes and study areas to allow for comparison in different 
geographic locations. The report must be submitted to the Director, 
Office of Protected Resources, NMFS, either within three months after 
the end of the calendar year, or within three months after the 
conclusion of the monitoring year, to be determined by the Adaptive 
Management process. This report will describe progress of knowledge 
made with respect to intermediate scientific objectives within the MITT 
Study Area associated with the Integrated Comprehensive Monitoring 
Program (ICMP). Similar study questions must be treated together so 
that progress on each topic can 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 will describe progress of knowledge made with respect to 
monitoring study questions across multiple Navy ranges associated with 
the ICMP. Similar study questions must be treated together so that 
progress on each topic can 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 the Navy to provide a cohesive 
monitoring report covering multiple ranges (as per ICMP goals), rather 
than entirely separate reports for the MITT, Hawaii-Southern 
California, Gulf of Alaska, and Northwest Study Areas.
    (e) Annual MITT Study Area training exercise report and testing 
activity reports. Each year, the Navy must 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 
the LOA to the Director, Office of Protected Resources, NMFS. Each 
year, the Navy must submit a detailed report to the Director, Office of 
Protected Resources, NMFS, within three months after the one-year 
anniversary of the date of issuance of the LOA. The MITT Annual 
Training Exercise Report and Testing Activity

[[Page 5900]]

Report 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 report must contain information on the total hours 
of operation of MFI surface ship hull-mounted mid-frequency active 
sonar used in the Marpi Reef and Chalan Kanoa Reef Geographic 
Mitigation Areas, major training exercises (MTEs), Sinking Exercise 
(SINKEX) events, and a summary of all sound sources used, including 
within specific mitigation reporting areas as described in paragraph 
(e)(3) of this section. The analysis in the detailed report must be 
based on the accumulation of data from the current year's report and 
data collected from previous annual reports. The annual report will 
also contain cumulative sonar and explosive use quantity from previous 
years' reports through the current year. Additionally, if there were 
any changes to the sound source allowance in a given year, or 
cumulatively, the report would include a discussion of why the change 
was made and include analysis to support how the change did or did not 
affect the analysis in the MITT EIS/OEIS and MMPA final rule. The 
annual report would also include the details regarding specific 
requirements associated with specific mitigation areas. The analysis in 
the detailed report would be based on the accumulation of data from the 
current year's report and data collected from previous reports. The 
final annual/close-out report at the conclusion of the authorization 
period (year seven) would also serve as the comprehensive close-out 
report and include both the final year annual use compared to annual 
authorization as well as a cumulative seven-year annual use compared to 
seven-year authorization. The detailed reports must contain information 
identified in paragraphs (e)(1) through (6) of this section.
    (1) MTEs. This section of the report must contain the following 
information for MTEs conducted in the MITT 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, and other platforms 
participating in exercise.
    (G) Total hours of all active sonar source operation.
    (H) Total hours of each active sonar source bin.
    (I) Wave height (high, low, and average) during exercise.
    (ii) Individual marine mammal sighting information for each 
sighting in each exercise where mitigation was implemented:
    (A) Date/Time/Location of sighting.
    (B) Species (if not possible, indication of whale or dolphin).
    (C) Number of individuals.
    (D) Initial Detection Sensor (e.g., sonar, Lookout).
    (E) Indication of specific type of platform observation was 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 was less than 200 yd, 200 to 500 
yd, 500 to 1,000 yd, 1,000 to 2,000 yd, or greater than 2,000 yd from 
sonar source.
    (K) Whether operation of sonar sensor was delayed, or sonar was 
powered or shut down, and how long the delay.
    (L) If source in use was hull-mounted, true bearing of animal from 
the vessel, true direction of vessel's travel, and estimation of 
animal's motion relative to vessel (opening, closing, parallel).
    (M) Lookouts must 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.) and if any calves were 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 
must identify the specific observations that support any conclusions 
the Navy reaches about the effectiveness of the mitigation.
    (2) SINKEXs. This section of the report must 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, and other platforms, 
participating in exercise.
    (H) Wave height in feet (high, low, and average) during exercise.
    (I) 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 for each sighting where mitigation was implemented.
    (A) Date/Time/Location of sighting.
    (B) Species (if not possible, indicate whale or dolphin).
    (C) Number of individuals.
    (D) Initial detection sensor (e.g., sonar or Lookout).
    (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 (or target 
spot if not yet detonated): Less than 200 yd, 200 to 500 yd, 500 to 
1,000 yd, 1,000 to 2,000 yd, or greater than 2,000 yd.
    (J) Lookouts must 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 were present.
    (K) The report must indicate whether explosive detonations were 
delayed, ceased, modified, or not modified due to marine mammal 
presence and for how long.
    (L) If observation occurred while explosives were detonating in the 
water, indicate munition type in use at time of marine mammal 
detection.
    (3) Summary of sources used. This section of the report must 
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 transducers and
    (ii) Total annual expended/detonated ordinance (missiles, bombs, 
sonobuoys, etc.) for each explosive bin.
    (4) MITT Study Area Mitigation Areas. The Navy must report any use 
that occurred as specifically described in these areas. Information 
included in the classified annual reports may be

[[Page 5901]]

used to inform future adaptive management of activities within the MITT 
Study Area.
    (5) Geographic information presentation. The reports must present 
an annual (and seasonal, where practical) depiction of training and 
testing bin usage geographically across the MITT Study Area.
    (6) Sonar exercise notification. The Navy must submit to NMFS 
(contact as specified in the LOA) an electronic report within fifteen 
calendar days after the completion of any MTE indicating: (i) Location 
of the exercise; (ii) Beginning and end dates of the exercise; and 
(iii) Type of exercise.
    (f) Seven-year annual/close-out report. The final (year seven) 
draft annual/close-out report must be submitted within three months 
after the expiration of this subpart to the Director, Office of 
Protected Resources, NMFS. NMFS must submit comments on the draft 
close-out report, if any, within three months of receipt. The report 
will be considered final after the Navy has addressed NMFS' comments, 
or three months after the submittal of the draft if NMFS does not 
provide comments.


Sec.  218.96   Letters of Authorization.

    (a) To incidentally take marine mammals pursuant to the regulations 
in this subpart, the Navy must apply for and obtain an LOA in 
accordance with Sec.  216.106 of this chapter.
    (b) An LOA, unless suspended or revoked, may be effective for a 
period of time not to exceed August 3, 2027.
    (c) If an LOA expires prior to August 3, 2027, the Navy may apply 
for and obtain a renewal of the LOA.
    (d) In the event of projected changes to the activity or to 
mitigation, monitoring, or reporting (excluding changes made pursuant 
to the adaptive management provision of Sec.  218.97(c)(1)) required by 
an LOA issued under this subpart, the Navy must apply for and obtain a 
modification of the LOA as described in Sec.  218.97.
    (e) Each LOA will set forth:
    (1) Permissible methods of incidental taking;
    (2) Geographic areas for incidental taking;
    (3) Means of effecting the least practicable adverse impact (i.e., 
mitigation) on the species or stocks of marine mammals and their 
habitat; and
    (4) Requirements for monitoring and reporting.
    (f) Issuance of the LOA(s) must be based on a determination that 
the level of taking is consistent with the findings made for the total 
taking allowable under the regulations in this subpart.
    (g) Notice of issuance or denial of the LOA(s) will be published in 
the Federal Register within 30 days of a determination.


Sec.  218.97   Renewals and modifications of Letters of Authorization.

    (a) An LOA issued under Sec. Sec.  216.106 of this chapter and 
218.96 for the activity identified in Sec.  218.90(c) may be renewed or 
modified upon request by the applicant, provided that:
    (1) The planned specified activity and mitigation, monitoring, and 
reporting measures, as well as the anticipated impacts, are the same as 
those described and analyzed for the 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) were implemented.
    (b) For LOA modification or renewal requests by the applicant that 
include changes to the activity or to 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 stock or years), NMFS may publish a notice of planned 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. Sec.  216.106 of this chapter and 
218.96 may be modified by NMFS under the following circumstances:
    (1) Adaptive management. After consulting with the Navy regarding 
the 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.
    (i) Possible sources of data that could contribute to the decision 
to modify the mitigation, monitoring, or reporting measures in an LOA 
include:
    (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 the regulations in 
this subpart or subsequent LOAs.
    (ii) If, through adaptive management, the modifications to the 
mitigation, monitoring, or reporting measures are substantial, NMFS 
will publish a notice of planned 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. Sec.  216.106 
of this chapter and 218.96, 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.  218.98  [Reserved]

[FR Doc. 2020-00481 Filed 1-30-20; 8:45 am]
 BILLING CODE 3510-22-P