Rule2025-19806
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Military Readiness Activities in the Atlantic Fleet Training and Testing Study Area
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
November 7, 2025
Effective
November 14, 2025
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS, upon request from the U.S. Department of the Navy (including the U.S. Navy and the U.S. Marine Corps (Navy)) and on behalf of the U.S. Coast Guard (Coast Guard; hereafter, Navy and Coast Guard are collectively referred to as Action Proponents), issues these regulations pursuant to the Marine Mammal Protection Act (MMPA) to govern the taking of marine mammals incidental to training and testing activities conducted in the Atlantic Fleet Training and Testing (AFTT) Study Area over the course of 7 years from November 2025 through November 2032. These regulations, which allow for the issuance of letters of authorization (LOAs) for the incidental take of marine mammals during specified activities and timeframes, prescribe the permissible methods of taking and other means of effecting the least practicable adverse impact on marine mammal species and their habitat, and establish requirements pertaining to the monitoring and reporting of such taking. The Action Proponents' activities are considered military readiness activities pursuant to the MMPA, as amended by the National Defense Authorization Act for Fiscal Year 2004 (2004 NDAA) and the NDAA for Fiscal Year 2019 (2019 NDAA).
Full Text
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[Federal Register Volume 90, Number 214 (Friday, November 7, 2025)]
[Rules and Regulations]
[Pages 50504-50722]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-19806]
[[Page 50503]]
Vol. 90
Friday,
No. 214
November 7, 2025
Part II
Department of Commerce
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National Oceanic and Atmospheric Administration
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50 CFR Part 218
Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to Military Readiness Activities in the
Atlantic Fleet Training and Testing Study Area; Final Rule
Federal Register / Vol. 90, No. 214 / Friday, November 7, 2025 /
Rules and Regulations
[[Page 50504]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 218
[Docket No. 251030-0166]
RIN 0648-BN17
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Military Readiness Activities in
the Atlantic Fleet Training and Testing Study Area
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Final rule; notification of issuance of letters of
authorization.
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SUMMARY: NMFS, upon request from the U.S. Department of the Navy
(including the U.S. Navy and the U.S. Marine Corps (Navy)) and on
behalf of the U.S. Coast Guard (Coast Guard; hereafter, Navy and Coast
Guard are collectively referred to as Action Proponents), issues these
regulations pursuant to the Marine Mammal Protection Act (MMPA) to
govern the taking of marine mammals incidental to training and testing
activities conducted in the Atlantic Fleet Training and Testing (AFTT)
Study Area over the course of 7 years from November 2025 through
November 2032. These regulations, which allow for the issuance of
letters of authorization (LOAs) for the incidental take of marine
mammals during specified activities and timeframes, prescribe the
permissible methods of taking and other means of effecting the least
practicable adverse impact on marine mammal species and their habitat,
and establish requirements pertaining to the monitoring and reporting
of such taking. The Action Proponents' activities are considered
military readiness activities pursuant to the MMPA, as amended by the
National Defense Authorization Act for Fiscal Year 2004 (2004 NDAA) and
the NDAA for Fiscal Year 2019 (2019 NDAA).
DATES: Effective from November 14, 2025, through November 13, 2032.
ADDRESSES: A copy of the Action Proponents' incidental take
authorization (ITA) application and supporting documents, NMFS'
proposed and final rules and subsequent LOAs for these regulations, as
well as a list of the references cited in this document, may be
obtained online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities</a>. In case of problems accessing these documents, please call
the contact listed below (see FOR FURTHER INFORMATION CONTACT).
FOR FURTHER INFORMATION CONTACT: Alyssa Clevenstine, Office of
Protected Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Purpose and Need for Regulatory Action
These regulations, issued under the authority of the MMPA (16
U.S.C. 1361 et seq.), allow for the authorization of take of marine
mammals incidental to the Action Proponents' training and testing
activities (which qualify as military readiness activities) involving
the use of active sonar and other transducers, air guns, and explosives
(including in-water explosives and underwater detonations); pile
driving and vibratory extraction; and vessel movement in the AFTT Study
Area. The AFTT Study Area includes air and water space of the western
Atlantic Ocean along the east coast of North America, the Gulf of
America (formerly Gulf of Mexico), and portions of the Caribbean Sea,
covering approximately 2.6 million square nautical miles (nmi\2\; 8.9
million square kilometers (km\2\)) of ocean area (see figure 1.1-1 of
the application). Please see the Legal Authority for the Final Action
section for relevant definitions.
Legal Authority for the Final Action
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et
seq.) directs the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and either regulations
are proposed or, if the taking is limited to harassment, a notice of a
proposed authorization is provided to the public for review and the
opportunity to submit comment.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking; 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 the species or stocks for
taking for certain subsistence uses (referred to in shorthand as
``mitigation''); and requirements pertaining to the monitoring and
reporting of the 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 Analysis and Negligible Impact Determination
section discusses the definition of ``negligible impact.''
The 2004 NDAA (Pub. L. 108-136) amended section 101(a)(5) of the
MMPA to remove the ``small numbers'' and ``specified geographical
region'' provisions and amended the definition of ``harassment'' as
applied to a ``military readiness activity'' to read as follows
(section 3(18)(B) of the MMPA): (i) Any act that injures or has the
significant potential to injure a marine mammal or marine mammal stock
in the wild (Level A Harassment); or (ii) Any act that disturbs or is
likely to disturb a marine mammal or marine mammal stock in the wild by
causing disruption of natural behavioral patterns, including, but not
limited to, migration, surfacing, nursing, breeding, feeding, or
sheltering, to a point where such behavioral patterns are abandoned or
significantly altered (Level B Harassment). The 2004 NDAA also amended
section 101(a)(5)(A)(iii) of the MMPA, establishing that ``[f]or
military readiness activity . . . , 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.'' On August 13, 2018,
the 2019 NDAA (Pub. L. 115-232) amended section 101(a)(5)(A)(ii) of the
MMPA to allow incidental take regulations for military readiness
activities to be issued for up to 7 years.
Summary of Major Provisions Within the Final Rule
The major provisions of this rule are:
<bullet> Take of marine mammals by Level A harassment and/or Level
B harassment;
<bullet> Take of marine mammals by mortality or serious injury (M/
SI);
<bullet> Use of defined powerdown and shutdown zones (based on
activity);
<bullet> Measures to reduce the likelihood of vessel strikes;
<bullet> Activity limitations in certain areas and times that are
biologically important (i.e., for foraging, migration, reproduction)
for marine mammals;
<bullet> Implementation of a Notification and Reporting Plan (for
dead, live
[[Page 50505]]
stranded, or marine mammals struck by any vessel engaged in military
readiness activities); and
<bullet> Implementation of a robust monitoring plan to improve our
understanding of the environmental effects resulting from the Action
Proponents' training and testing activities.
This rule includes an adaptive management component that allows for
timely modification of mitigation, monitoring, and/or reporting
measures based on new information, when appropriate.
Summary of Request
On May 28, 2024, NMFS received an application from the Action
Proponents requesting authorization to take marine mammals, by Level A
and Level B harassment, incidental to training and testing
(characterized as military readiness activities) including the use of
sonar and other transducers, explosives, air guns, and impact and
vibratory pile driving and extraction conducted within the AFTT Study
Area. In addition, the Action Proponents requested authorization to
take, by serious injury or mortality, a limited number of several
marine mammal species incidental to use of explosives, ship shock
trials, and vessel movement during military readiness activities
conducted within the AFTT Study Area over the 7-year period of the
LOAs. In response to our comments and following information exchange,
the Action Proponents submitted a final revised application on August
16, 2024, that we determined was adequate and complete on August 19,
2024. On September 20, 2024, we published a notice of receipt (NOR) of
application in the Federal Register (89 FR 77106), requesting comments
and information related to the Action Proponents' specified activities.
During the 30-day public comment period, we did not receive any public
comments. On October 8, 2024, the Action Proponents submitted an
updated application to revise take estimates for a subset of Navy
activities. On January 21, 2025, the Action Proponents submitted an
updated application which removed ship shock trials and estimated take
associated with that activity within the Virginia Capes (VACAPES) Range
Complex. On February 13, 2025, the Action Proponents submitted an
updated application containing minor revisions. On May 9, 2025, we
published a proposed rule (90 FR 19858) and requested comments and
information related to the Action Proponents' request for 30 days. All
relevant comments received during the proposed rulemaking comment
period were considered in this final rule. Comments received on the
proposed rule are addressed in this final rule in the Comments and
Responses section.
NMFS has previously promulgated incidental take regulations
pursuant to the MMPA relating to similar military readiness activities
in the AFTT Study Area. NMFS published the first rule effective from
January 22, 2009 through January 22, 2014 (74 FR 4844, January 27,
2009), the second rule effective from November 14, 2013 through
November 13, 2018 (78 FR 73009, December 4, 2013), and the third rule
effective from November 14, 2018 through November 13, 2023 (83 FR
57076, November 14, 2018), which was subsequently amended, extending
the effective date through November 13, 2025 (84 FR 70712, December 23,
2019) pursuant to the 2019 NDAA. For this rulemaking, the Action
Proponents plan to conduct substantially similar training and testing
activities within the AFTT Study Area that were conducted under
previous rules.
The Action Proponents' 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 this rule account for interannual variability in
training and testing to meet evolving or emergent military readiness
requirements. These regulations cover military readiness activities in
the AFTT Study Area that will occur for a 7-year period following the
expiration of the pre-existing MMPA authorization after November 13,
2025.
Description of Specified Activity
The Action Proponents requested authorization to take marine
mammals incidental to conducting military readiness activities. The
Action Proponents have determined that acoustic and explosives
stressors are most likely to result in take of marine mammals in the
form of Level A and B harassment, and a limited number of takes by
serious injury or mortality may result from vessel movement and
explosive use including ship shock trials. NMFS concurs with these
determinations. Detailed descriptions of these activities are provided
in chapter 2 of the 2025 AFTT Supplemental Environmental Impact
Statement (EIS)/Overseas EIS (OEIS) (2025 AFTT Supplemental EIS/OEIS)
(<a href="https://www.nepa.navy.mil/aftteis/">https://www.nepa.navy.mil/aftteis/</a>) and in the Action Proponents'
application (<a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities</a>).
A detailed description of the specified activities was provided in
our proposed rule (90 FR 19858, May 9, 2025). NMFS hereby refers to the
information and analysis provided in the proposed rule which continue
to apply to this final rule. Since that time, no changes have been made
to the planned activities. Therefore, a detailed description is not
provided here. Please refer to the proposed rulemaking for the complete
description of the specified activity.
Foreign Navies
In furtherance of national security objectives, foreign militaries
may participate in multinational training and testing events in the
AFTT Study Area. Foreign military activities that are planned by and
under the substantial control and responsibility of the Action
Proponents are included in the specified activity. These participants
could be in various training or testing events described in appendix A
of the 2025 AFTT Supplemental EIS/OEIS, and their effects are analyzed
in this final rule. However, when foreign military vessels and aircraft
operate independently within the study area as sovereign vessels
outside the planning, control, and responsibility of the Action
Proponents, those activities are not considered part of the specified
activity. There are many reasons why foreign military vessels may
traverse U.S. waters or come into a U.S. port, not all of which are at
the request of any of the Action Proponents. Foreign military vessels
and aircraft operate pursuant to their own national authorities and
have independent rights under customary international law, embodied in
the principle of sovereign immunity, to engage in various activities on
the world's oceans and seas.
When foreign militaries are participating in a U.S. Navy-led
exercise or event, foreign military use of sonar and explosives, when
combined with the Action Proponents' use of sonar and explosives, would
not result in exceedance of the analyzed levels (within each Navy
Acoustic Effects Model (NAEMO) modeled sonar and explosive bin) used
for estimating predicted impacts, which formed the basis of our
acoustic impacts effects analysis that was used to estimate take in
this final rule. Please see the Mitigation Measures section and
Reporting section of this final rule for information about mitigation
and reporting related to foreign navy activities in the AFTT Study
Area.
[[Page 50506]]
Comments and Responses
We published the proposed rule in the Federal Register on May 9,
2025 (90 FR 19858) with a 30-day comment period. In that proposed rule,
we requested public input on our analyses, our preliminary findings,
and the proposed regulations, and requested that interested persons
submit relevant information and comments. During the 30-day comment
period, we received 1,216 comments. Of this total, one submission was
from the Marine Mammal Commission (Commission), two were from non-
governmental organizations Natural Resources Defense Council and Turtle
Island Restoration Network, and the remaining comments were from
private citizens. The majority of these comments were form letter
submissions containing identical or nearly identical content expressing
general opposition toward the Action Proponents' proposed training and
testing activities and requesting that NMFS not issue the regulations
and LOAs, but the commenters provided no specific recommendations or
supporting information. These general comments have been noted, but
because they did not include information pertinent to NMFS' decision,
they are not addressed further.
NMFS has reviewed and considered all relevant public comments
received on the proposed rule and issuance of the LOAs. All
substantive, relevant comments and our responses are described below.
We organize our comment responses by major categories.
Impact Analysis and Thresholds
Comment 1: The Commission stated that a 5-minute accumulation time
for an entire day of pile driving is insufficient, particularly because
of the Commission's assertion that the Navy does not implement, and
NMFS has not proposed to require, soft-start procedures during pile-
driving training activities. The Commission also noted differences in
pile driving between the proposed rule and another recent military
readiness activity involving pile driving (90 FR 20283, May 13, 2025).
The Commission recommended that NMFS revise: (1) the range to effects
for pile driving for temporary threshold shift (TTS) and auditory
injury (AUD INJ) based on the number of piles of each pile type and
installation method that would be installed on a given day, the number
of minutes or strikes needed to install each pile to depth, and the
correct source levels, including for vibratory installation of 24-inch
(0.61 meter (m)) sheet piles; (2) the range to effects for pile driving
for behavioral response for vibratory installation of 24-inch (0.61 m)
sheet piles based on a source level of 159 decibel referenced to 1
microPascal (dB re 1 [mu]Pa) at 11 m; and (3) the numbers of takes
accordingly for the final rule.
Response: NMFS disagrees with the Commission's assertion that the
source levels used for vibratory installation of 24-inch (0.61 m) sheet
piles are incorrect. As indicated in the proposed rule and the
technical report ``Quantifying Acoustic Impacts on Marine Mammals and
Sea Turtles: Methods and Analytical Approach for Phase IV Training and
Testing'' (U.S. Department of the Navy, 2024b), hereafter referred to
as the Acoustic Impacts Technical Report, a source level of 159 dB
root-means-square (RMS) for vibratory driving of 24-inch (0.61 m) steel
sheet piles measured at 10 m (32.8 feet (ft)) (NAVFAC, 2020) is a
reasonable representation of likely sound levels.
The Navy assumed, and NMFS concurred, that most animals in the area
of pile driving activities would avoid higher sound levels that could
cause injury over periods of time shorter than 5 minutes. The Navy is
required to shut down pile driving if a bottlenose dolphin occurs
within 100 yards (yd) (91.4 m) of the pile driving site. Since pile
driving occurs in relatively calm, shallow, coastal waters, and
Lookouts are on stationary platforms (e.g., elevated piers, bulkhead
walls), there is a high likelihood that marine mammals would be sighted
within or approaching the 100 yd (91.4 m) shutdown zone and mitigation
would be implemented, therefore preventing potential TTS or AUD INJ, as
all the predicted ranges for these effects are significantly smaller
than 100 yd (91.4 m). As such, Level A harassment from pile driving
activities is neither anticipated nor authorized, consistent with the
proposed rule.
Navy considers soft-start procedures for impact pile driving to be
part of its standard operating procedures. As such, neither the 2024
AFTT Draft Supplemental EIS/OEIS, application, nor the AFTT proposed
rule (90 FR 19858, May 9, 2025) listed soft start as a mitigation
measure. Navy states that its standard operating procedures are
essential to safety and mission success and are implemented regardless
of their secondary benefits, whereas its mitigation measures are
designed entirely for the purpose of avoiding or reducing impacts on
marine mammals. As such, the Action Proponents did not include a
description of the soft-start procedure in the mitigation section of
the application, and NMFS did not propose to include soft start as a
mitigation measure in the proposed rule. However, NMFS agrees with the
Commission that it is appropriate to require soft-start procedures as a
mitigation measure, and this final rule clarifies that the Navy must
implement soft start techniques for impact pile driving. Of note, Navy
continues to consider soft-start procedures as part of their standard
operating procedures, and as such, they are not listed as a mitigation
measure in the 2025 AFTT Supplemental EIS/OEIS.
Comment 2: The Commission recommended that NMFS work with the Navy
to use an avoidance swim speed of no more than 2 meters per second (m/
second) for harbor porpoises and 1 m/second for pinnipeds, and to
revise the NAEMO modeling and take estimates appropriately for the
final rule. The Commission further recommended that NMFS work with the
Navy to incorporate moving animats (i.e., a virtual animal) into NAEMO
that can actively avoid sound sources based on species-specific dive
profiles and swim speeds for Phase V activities (which would occur in
AFTT from 2032 to 2039) and, if that is not feasible, incorporate
species-specific swim speeds and the actual modeled sound propagation
into NAEMO to simulate avoidance for a given event. The Commission
stated that both creating an emulator and running simulation studies
outside of NAEMO, as recommended by Simmons et al. (2025), should
inform how best to deal with moving animats and implementing avoidance
within NAEMO.
Response: NMFS and the Navy acknowledge the importance of using
appropriate swim speeds in the avoidance analysis in NAEMO, which
assesses the potential for marine mammals to mitigate high-intensity
sound exposures that could lead to auditory injury. While baseline swim
speeds can be informative, the Navy prioritized data on swim behavior
observed near and during anthropogenic disturbance because these data
were considered more representative of how animals might respond to
acoustic stimuli and potentially reduce injury risk. NMFS concurs with
this approach.
The Commission referenced a study by Kastelein et al. (2018) as
support for a lower harbor porpoise swim speed. However, the cited
speed of 7.1 kilometers per hour (km/hr) represents the sustained
average speed of a single captive harbor porpoise in a relatively small
pool during a pile driving playback study at exposures below those
causing auditory injury. This specific observation does not accurately
reflect the full range of harbor porpoise swim capabilities. As
documented in
[[Page 50507]]
table 8 of the appendix to the Acoustic Impacts Technical Report, data
from free-swimming harbor porpoises indicate swim speeds up to and
exceeding 3 m/second, supporting the Navy's chosen value for modeling
avoidance.
For pinnipeds, the avoidance analysis used a reasonable swim speed
of 2 m/second for a limited duration (10 minutes), acknowledging the
lack of observed data on their swim behavior during acoustic exposures.
This assumption balances the need for a realistic representation of
potential avoidance behavior with the limited data availability,
contributing to a conservative assessment of potential impacts.
The Navy's approach to modeling impacts is described in the
Acoustic Impacts Technical Report. NMFS has reviewed the Acoustic
Impacts Technical Report and concurs with Navy that the approach is
based on the best available science. In early NAEMO development, the
Navy compared the number of exposures (i.e., >120 dB) using the Marine
Mammal Movement and Behavior (3MB) model versus horizontally stationary
animats and concluded that there was no significant difference in
behavioral exposures between the two distribution methods. Thus,
horizontally stationary animats were selected for computational
efficiency.
NMFS and the Navy recognize the evolving nature of modeling
techniques and acknowledge the Commission's desire for more dynamic and
species-specific avoidance behaviors in future iterations of NAEMO.
NMFS has encouraged the Navy to continue to explore NAEMO enhancements,
and the Navy has indicated that it will consider species-specific swim
speeds and potentially more complex movement models, as data
availability and computational capabilities allow. Currently, however,
detailed avoidance data for many species are limited, necessitating the
use of surrogate data and generalized approaches, as is also the case
with dive profiles.
The Navy states that it will continue to prioritize research and
development efforts to enhance the accuracy of its impact modeling
tools, ensuring the best available science informs its environmental
assessments.
Comment 3: The Commission recommended that NMFS work with the Navy
to use NAEMO to conduct modeling of both multi-day events and multiple
single-day events to estimate the number of repeated exposures an
individual is expected to incur and to better assess repeated exposures
of individuals and population-level consequences, rather than rely on
what it called a qualitative assessment. The Commission cited Simmons
et al. (2025) recommendation of ways that NAEMO and results from NAEMO
could be better used to estimate repeated takes and population-level
impacts.
Response: NMFS and the Navy have had ongoing discussions about how
to better assess and characterize the number of repeated takes of
individuals from training and testing activities, including whether
NAEMO could be used to generate estimates of repeated takes of
individuals. A credible assessment of the repeated takes due to the
specified activities per the approach suggested in the comment would
require treating animats as unique individuals over the course of a
year's activity and across a large study area, while incorporating
migration patterns and nomadic movement. Such an effort would be
computationally intensive and Navy anticipates that it is likely
infeasible given reasonable resources. In contrast, the action analyzed
by Zeddies et al. (2017) and referenced by the Commission in supporting
statements was less complex than the specified activities. Thus,
Zeddies et al. (2017) could assess repeated takes within spatially and
temporally limited areas with undirected animal ingress/egress. NMFS
will continue to work with the Navy to better assess and characterize
the number of repeated takes of individuals. Of note, Simmons et al.
(2025), referenced by the Commission, was written after a joint
workshop with the Navy and SMRU Consulting. Recommendations from the
workshop and associated report are being considered for future modeling
improvements.
While NMFS and the Action Proponents' analyses could be further
refined, the information in NMFS' analysis is sufficient for assessing
whether the authorized take would have a negligible impact on the
species or stocks of marine mammals, and it is not necessary to have
exact number of times that an animal is estimated to be repeatedly
taken in order to make the determination. As described in the
Preliminary Analysis and Negligible Impact Determination section of the
proposed rule (90 FR 19858, May 9, 2025) and this final rule, 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 (number of takes to population abundance) to give us a relative
sense of where a larger portion of a species is being taken by the
specified activities, where there is a likelihood that the same
individuals are being taken across multiple days, and whether the
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 some subset of
animals is known to congregate in an area in which activities are
regularly occurring (e.g., a small resident population, takes occurring
in a known important area such as a Biologically Important Area (BIA),
or a large portion of the takes occurring in a certain region and
season), the overall likelihood and number of repeated takes is
generally considered low, as it could, on one extreme, mean that every
take represents a separate individual in the population being taken on
1 day (a minimal impact to an individual) or, more likely, that some
smaller number of individuals are taken on 1 day annually and some are
taken on a few, not likely sequential, days annually, and of course
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 would be exposed multiple times, but based on
the nature of the specified activities and the movement patterns of
marine mammals, it is unlikely that individuals from most stocks would
be taken over more than a few days within a given year. 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 taken on
only a small percentage of the days of the year. The greater likelihood
is that
[[Page 50508]]
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, for most species or
stocks, any individuals would be taken a significant portion of the
days of the year.
Of note, the Commission identified an error related to potential
impacts to goose-beaked whales (Western North Atlantic stock) in the
Preliminary Assessment and Negligible Impact Determination section of
the proposed rule. This final rule includes a correction to that
language to indicate that the impacts to the Western North Atlantic
stock of goose-beaked whales could cause a limited number of females to
forego reproduction for a year.
Comment 4: The Commission recommended that NMFS work with the Navy
to use its Range-Dependent Acoustic Model and the Navy's Standard
Parabolic Equation (RAM/PE) model for non-impulsive sources to model
all underwater detonations (i.e., impulsive sources) for Phase IV
activities for which modeling has not been completed and for all Phase
V activities, until such time that Comprehensive Acoustic Simulation
System/Gaussian Ray Bundle (CASS/GRAB) and the similitude equation have
been validated for the range of detonation sizes and environmental
parameters (i.e., water depth and receiver range) in which it would be
used. They supported this recommendation by stating that, given the
comparability of the modeled zones from the Peregrine version of RAM/PE
to the measured values and that RAM/PE is already used by the Navy for
modeling non-impulsive sources that operate at less than 100 Hertz (Hz)
and in shallow water, the Navy has the data to conduct a rigorous
comparison of CASS/GRAB and the similitude equation and the in situ
measurements of the USS Ford ship shock trial from Seger et al. (2023)
to fulfill the project's intent and to inform future rulemakings.
Response: Navy has indicated that it plans to conduct a
verification of the impulsive propagation methods in NAEMO using the
Seger et al. (2023) data, which was published by Madhusudhana et al.
(2024).
The NAEMO impulsive modeling methods, as described in the Acoustic
Impacts Technical Report, require arrival times, sound levels, and
phases to be output from the propagation model. RAM/PE does not output
the time information necessary for simulation and is thus not a
suitable option for impulsive modeling in NAEMO. The limitations of the
similitude equation are discussed in section 4.1.3.2 of the Acoustic
Impacts Technical Report and comparisons between the peak pressure
computed at various ranges against the theoretical value based on the
similitude equation showed agreement, providing confidence that the
similitude equation was appropriate for use in NAEMO.
The Navy states that it is committed to ensuring the accuracy of
its impulsive propagation models and recognizes the importance of
ongoing validation efforts. While the similitude equation has been
evaluated and demonstrated good agreement with measured data, as
detailed in section 4.1.3.2 of the Acoustic Impacts Technical Report,
the Navy is open to exploring alternative approaches to meet NAEMO's
requirements.
Comment 5: The Commission highlighted multiple points regarding the
behavioral response functions (BRF) following its review of the
technical report ``Criteria and Thresholds for U.S. Navy Acoustic and
Explosive Effects Analysis (Phase 4)'' (U.S. Department of the Navy,
2024a), which was revised to include updates to the version published
in September 2024 and is hereafter referred to as the revised Criteria
and Thresholds Technical Report (U.S. Department of the Navy, 2025).
These points generally relate to the upper bound of the BRFs, Southall
et al. data, odontocete BRFs, sensitive species BRFs, harbor porpoise
data, pinniped BRFs, response severity denotation, and inconsistencies
in some tables and figures. Please see the Commission's letter for a
detailed discussion of its recommendation.
The Commission recommended that NMFS require the Navy to revise
their criteria and thresholds to clarify and address these points, as
that document underpins the current and future Phase IV rulemakings.
The Commission also states that to increase efficiency for all of the
agencies involved and to ensure accurate information is being provided
for public comment, the Commission would welcome the opportunity to
informally review future versions of the Navy's criteria and threshold
documents. The Commission further recommends that NMFS work with the
Navy to use the dose-response functions that were developed from all of
the raw data rather than those that were regenerated for only moderate
and severe responses and to refrain from extrapolating beyond the
bounds of the underlying data when revising the BRFs.
In a related comment, a commenter stated that NMFS has not
incorporated recent behavioral response data on common dolphins
(Southall et al., 2024), and other important studies highlighted by the
Commission, into its biphasic risk functions. The commenter references
a fuller description of its concern in a comment on the 2024 Hawaii-
California Training and Testing (HCTT) Draft EIS/OEIS.
Response: Regarding the upper bound of the BRFs, the Navy adjusted
the upper bound of the BRFs in Phase IV to more accurately reflect
observed behavioral data, particularly at higher received levels. For
example, sonar received levels between 170 and 182 dB re 1 [micro]Pa
for humpback whales during 3S2 study (the second phase of the Sea
Mammals, Sonar, Safety (3S) project) and between 175 and 186 dB re 1
[micro]Pa for sperm whales during 3S3 study (the third phase of the 3S
project) did not elicit observable responses. See section 3.1.6.1.2 of
the Criteria and Thresholds Technical Report for discussion of the 3S
and 3S2 study, and section and 3.1.6.1.3 for discussion of the 3S3
study. Please see table E-1 in the revised Criteria and Thresholds
Technical Report for details of all individual responses documented
during studies in conjunction with received levels of sonar and sonar
like sources.
Extending the upper bound to 200 dB re 1 [micro]Pa allows the BRFs
to account for this lack of response at higher received levels. This
adjustment does not arbitrarily shift the entire curve to the right, as
the Commission suggests. For groups like pinnipeds, where responses are
consistently observed at lower received levels, the BRF approaches 100
percent response probability at 185 dB re 1 [micro]Pa. Therefore, the
upper bound adjustment primarily impacts the odontocete and mysticete
BRFs, reflecting the observed data at higher exposures. It is also
important to note that the lower bound of the BRFs were extended to 90
dB re 1 [micro]Pa in Phase IV (compared to the 100 dB re 1 [micro]Pa
lower limit used in Phase III), further demonstrating that the
adjustments were not solely focused on increasing the upper bound.
The Commission's observation of a flat slope between 185 and 200 dB
re 1 [micro]Pa for the Phase III BRFs shown in figure 42 (Department of
the Navy, 2024a) was a result of anchoring the Phase III BRFs at 185 dB
re 1 [micro]Pa and then extending them to 200 dB re 1 [micro]Pa for
plotting purposes.
Finally, regarding the point that the upper level of the mysticete
BRF exceeds the TTS onset, it is important to emphasize that auditory
and behavioral criteria are not directly linked. The Navy recognizes
the evolving nature of acoustic science and
[[Page 50509]]
will continue to refine its effects criteria as new data and
understanding become available.
The descriptions of responses in appendix E (Behavioral Responses
to Sonar and Sonar-Like Sources: All Individuals Included) of the
revised Criteria and Thresholds Technical Report have been updated to
include additional information on the observed responses.
Regarding data from Southall et al. (2024), the Navy develops its
BRFs using the best available scientific data. While data from the
Atlantic behavioral response study (BRS) cited by the Commission and
Southall et al. (2024) cited by the commenter were collected during the
timeframe referenced, these data were not available for use in the
development of the BRFs for Phase IV. These functions are always
developed in close consultation with scientists conducting BRS/
controlled exposure experiment (CEE) studies, but when the data are not
yet published, the researchers determine the appropriate time at which
to share data with the Navy. In this case, Atlantic BRS behavioral
response results and Southall et al. (2024) were not shared in time to
be considered and/or included in the development of the Navy risk
thresholds. The Navy did consider data from Southall et al. (2024) in
appendix D of the 2025 AFTT Supplemental EIS/OEIS, indicating the
potential responses observed in this study occurred at received levels
and distances assessed for potentially significant behavioral responses
in the analysis of Phase IV; however, the findings of this study do not
change the conclusions made by the Navy nor NMFS' determination. The
Navy remains committed to incorporating the best available scientific
data into its impact assessments and will revisit its BRFs as new
information, including the published results of the Atlantic BRS,
becomes available.
Regarding the odontocete BRF, all the data from Houser et al.
(2013a, 2013b) were included in the modified risk functions developed
for subsampling in the Navy's BRFs. However, low-severity responses
were classified as ``non-responses'' when deriving the BRFs (see also
Southall et al. (2021) for a description of severity scoring). This
approach, consistent with Phase III, reflects that low-severity
behavioral responses are not typically considered ``harassment'' under
the MMPA during military readiness activities. To balance field and
captive study data, a subsampling method was used. This involved
creating modified risk functions incorporating the new scoring values
(classifying low-severity responses as non-responses) at different
received levels. Thirty data points were then randomly selected from
the bottlenose dolphin risk function generated using this method. This
subsampling approach, similar to that used for beaked whale data in
both Phase III and Phase IV, ensures each individual animal from the
captive study receives equal weight, comparable to individuals from
field studies. This allows for a more comprehensive consideration of
exposures and responses for each species, unlike Phase III's selection
of a single response level per individual. The Navy has clarified this
methodology in the revised Criteria and Thresholds Technical Report.
Further, the Navy's current odontocete BRF considers the potential for
behavioral responses that may qualify as ``harassment'' under the MMPA
for military readiness activities at the estimated received levels in
Southall et al. (2024).
Regarding the sensitive species BRF, while the generalized additive
model (GAM) published in Jacobson et al. (2022) only extended to 165
dB, the Navy requested that authors rerun their model to 200 dB to
create a new curve that could be subsampled for the Navy Phase IV risk
function; the same was done for the Moretti et al. (2014) data.
Therefore, the two beaked whale range-based risk functions extended to
the same bandwidth as the Navy BRF and the subsampling matched the rest
of the data. The Navy has updated the Criteria and Thresholds Technical
Report to reflect that the published GAMs were rerun with the broader
bandwidth. Both Moretti et al. (2014) and Jacobson et al. (2022) were
subsampled 10 times each.
To be included in the BRF, data sets needed to relate known or
estimable received levels to observations of individual or group
behavior. The data in Falcone et al. (2017) is not included in the
development of the BRFs because it is not possible to reasonably
estimate the received levels in this study; however, this data was
considered in developing the distance conditions for the application of
the sensitive species BRF.
The Navy is committed to ensuring scientific integrity in datasets
used for BRF development. Using data that do not meet these criteria
could result in unreliable or misleading risk assessments. A risk
function has not yet been fit to Southern California Anti-Submarine
Warfare Range (SOAR) data for beaked whales, nor has one been fit for
minke whales at PMRF. The BRFs in Phase IV utilized only individual
response-received level data outside of the four pre-existing risk
functions that were subsampled. There were no individual response-
received level data available for beaked whales at SOAR nor for minke
whales at PMRF, therefore those data were not used in the Phase IV
BRFs. As science continues to evolve, the Navy will continue to refine
its effects criteria. The Navy remains committed to incorporating new
data and analyses, including those from SOAR and PMRF, as they become
available and meet the rigorous standards required for robust BRF
development.
Regarding the Kastelein harbor porpoise data, when the same
individuals were tested at multiple received levels for the same source
within a single study, only the lowest received level eliciting a
response was included in the data used for BRF development. However, in
some studies, Kastelein tested the same sources using different
parameters, such as an upsweep versus a downsweep signal (e.g.,
Kastelein et al. (2014b), where both low frequency and mid frequency
active sonar signals were tested as both a downsweep and upsweep), or
as a continuous versus pulsed active sonar signal (e.g., Kastelein et
al., 2018). In that case, the response to both signal parameters would
have been used in the BRF as those would be considered different
signals. The citations for the relevant Kastelein studies, previously
provided in tables 19 and 20, have been added to table E-1 in the
revised Criteria and Thresholds Technical Report.
Regarding the pinniped BRFs, the Navy confirms that all data from
the Houser et al. (2013a) California sea lion controlled exposure
experiment were considered in developing the Phase IV BRFs. However, as
with the odontocete BRF, low-severity responses were classified as
``non-responses'' when deriving the BRF. This decision aligns with the
Navy's approach to assessing potential harassment under the MMPA during
military readiness activities, where low-severity responses are not
typically considered indicative of harassment. The original curves
developed by Houser et al. (2013a) were not used because they included
the low-severity responses as responses. The Navy has clarified this
approach in the revised Criteria and Thresholds Technical Report.
Regarding the identified inconsistencies in some data, tables, and
figures, NMFS and the Navy have carefully reviewed those identified in
the Commission's comments and the Navy has made the necessary
corrections to the revised Criteria and
[[Page 50510]]
Thresholds Technical Report. These revisions ensure consistency in the
reported ranges of received levels, distances, and significant
responses across the executive summary, tables, figures, and
accompanying text. Specifically, the Navy updated table E-1 in the
revised Criteria and Thresholds Technical Report to include data for
Blainville's beaked whales from Tyack et al. (2011). The studies by
Moretti et al. (2014) and Jacobson et al. (2022) involved aggregated
and modeled data rather than individual animal responses and were
therefore incorporated into the BRFs through a random subsampling
process, as described in the Criteria and Thresholds Technical Report,
rather than being presented directly in table E-1, which focuses on
individual-level data. The Navy also addressed inconsistencies between
Cur[eacute] et al. (2025) and table E-1 of U.S. Department of the Navy
(2025) identified by the Commission. The Navy updated the closest
points of approach so that the onset closest point of approach is given
for signals that elicited significant responses, while the closest
point of approach of the overall exposure session is given for signals
that did not elicit a significant response. These corrections only
affect the way data was presented in table E-1 and do not change the
BRFs.
Finally, the Navy has confirmed to NMFS that it used the data from
Houser et al. (2013a) and Houser et al. (2013b) to develop the new risk
functions. As noted previously, low-severity responses were scored as
``non-responses'' within these functions to align with the Navy's
approach to assessing potential harassment under the MMPA. These new
risk functions were then subsampled using the same method applied to
the beaked whale range risk functions in both Phase III and Phase IV,
ensuring consistency in the Navy's treatment of such data. This
subsampling approach, described in detail within those reports, ensures
appropriate weighting of individual responses and contributes to the
robustness of the Navy's BRFs.
Regarding the Commissions' offer to informally review future
versions of the criteria and threshold reports, NMFS recommends that
the Commission coordinate directly with the Navy for any potential
early reviews as the Navy is the primary author.
Comment 6: The Commission recommended that NMFS work with the Navy
in a concerted manner to incorporate data that support criteria and
threshold development more often than on a decadal cycle and to revise
NAEMO to implement the relevant criteria and thresholds at a true post-
processing stage so that animat dosimeter data can be re-queried if
thresholds change, rather than needing to remodel the animat-portion of
NAEMO.
Response: The criteria and thresholds are typically updated at the
beginning of each at-sea phase. This is a significant effort that
involves collecting published data, working with marine mammal
researchers to collect and understand emergent data, developing methods
to incorporate the data, writing and publishing the technical report,
and seeking approvals from Navy leadership and NMFS. Nevertheless,
emergent data is continuously assessed against the current criteria and
thresholds to ascertain whether it would create significant changes to
the Navy's analysis. If so, the analysis would be altered to reflect
this emergent data.
The Navy is continuously reassessing and evolving its analysis
methods including the need to more frequently update criteria and
threshold and the feasibility for NAEMO to more rapidly incorporate
such changes. For example, the Navy has undertaken efforts to
investigate the feasibility of moving the weighting functions to the
post-processor for impulsive modeling, which would allow added
flexibility to the modeling process when new data emerges outside of
the normal criteria and threshold timeline. NMFS supports such efforts.
Comment 7: The Commission recommended that NMFS determine whether
inclusion of data from Kastelein et al. (2024a, 2025a, 2025b) would
alter the weighting functions and/or thresholds for the functional
hearing groups and, if so, whether those modifications would be
sufficient to warrant revision of the weighting functions and
associated thresholds for non-impulsive sources as stipulated in their
criteria and thresholds.
Response: Whether and when to share data for ongoing research is at
the discretion of the researchers and funding agencies. Because the
specific data from Kastelein et al. (2024) were not shared with the
Navy prior to peer review and publication, these data could not be
incorporated into the development of the Phase IV Criteria and
Thresholds. However, the Navy's current approach using the existing
Phase IV criteria remains protective even when compared to the findings
of Kastelein et al. (2024a). Specifically, incorporating the TTS onset
value of 169 dB sound exposure level (SEL) reported by Kastelein et al.
(2024a) would raise the very high frequency (VHF) non-impulse exposure
function by 4 dB. The impact on other impulsive and non-impulsive
exposure functions is negligible (1 dB or less).
NMFS has also reviewed the data from Kastelein et al. (2024b,
2025a, 2025b). Kastelein et al. (2025a) evaluated the effect of one-
sixth octave band noise centered at 40 kilohertz (kHz) on TTS in two
California sea lions (Zalophus californianus). Results indicate that
TTS onset (6 dB threshold shift) occurred at approximately 169 dB
cumulative SEL, which is lower than predicted by the current Phase IV
TTS threshold and weighting function. Interestingly, this TTS onset
level is lower than what was measured during exposure to 32 kHz in a
previous study (179 dB cumulative SEL; Kastelein et al. (2024b)). So,
despite hearing sensitivity decreasing at higher frequencies, Kastelein
et al. (2025a) indicate that TTS onset occurs at a lower level than
predicted, which contradicts typical trends in TTS onset previously
measured in marine mammals. Thus, these data suggest a need to evaluate
exposures at potentially higher frequencies to examine whether this
disparate trend continues.
Kastelein et al. (2025b) examined TTS in two harbor seals (Phoca
vitulina) exposed to one-sixth octave band noise centered at 8 kHz. In
this study, TTS onset (6 dB threshold shift) occurred at approximately
181 dB cumulative SEL, which is higher than what is predicted with the
current Navy Phase IV criteria.
In consideration of the information discussed above, NMFS and Navy
have concluded that revisions to the Phase IV Criteria and Thresholds
are not warranted at this time.
Comment 8: The Commission recommended that NMFS determine whether
the low-frequency (LF) cetacean weighting function has been shifted far
enough to the higher frequencies to reflect that 32 kHz was the most
sensitive frequency tested in minke whales, determine whether use of
the phocid carnivore in water (PCW) composite audiogram, weighting
function, and threshold parameters are more representative of very low-
frequency (VLF) and LF cetaceans than medians and means of the five
other functional hearing groups, and work with the Navy to revise the
VLF and LF cetacean composite audiograms, weighting functions, and
thresholds as needed for impulsive and non-impulsive sources for the
final rule and 2025 AFTT Supplemental EIS/OEIS.
In a related comment, a commenter stated that NMFS has applied a
patently unrealistic, non-conservative auditory weighting scheme for
``low frequency cetaceans'' and references a similar
[[Page 50511]]
comment on the 2024 HCTT Draft EIS/OEIS.
Response: The lack of data on mysticete hearing, especially in
terms of the impacts of noise on hearing, has made this a challenging
group for which to develop acoustic criteria. The Navy has split the
mysticetes into two hearing groups for its Phase IV analyses: VLF and
LF cetaceans (see appendix B of the Criteria and Thresholds Technical
Report). This decision is outlined in detail within the documentation
and includes the best available science including the recommendations
of Southall et al. (2019a) and the minke whale study by Houser et al.
(2024). The Navy was given access to pre-published data on the 2023/
2024 minke whale field season and was able to incorporate into their
Phase IV criteria (noting, as the commenter did that the 2023 field
season data was published in November 2024). In their Phase IV
criteria, the Navy separated VLF cetaceans (i.e., blue, fin, right, and
bowhead whales) from LF cetaceans (all other mysticetes). Thus, they
are acknowledging differences among mysticetes species.
NMFS and the Navy disagree that wholesale adoption of the PCW
parameters or shifting the LF weighting function solely based on the 32
kHz sensitivity of minke whales is scientifically justified. There is
no scientific evidence to support the exclusive use of the PCW
composite audiogram and weighting function parameters for the LF and
VLF groups. Adolescent minke whales were tested by Houser et al. (2024)
specifically because of their small size compared to other baleen
whales. Smaller head size generally facilitates hearing at higher
frequencies, so a shift of the entire LF curve (intended to represent
all species within the hearing group) to a center frequency of 32 kHz
is not likely representative of most baleen whales, which are larger in
size compared to adolescent minke whales.
Therefore, the Navy maintains, and NMFS concurs, that, based on the
weight of the evidence, the existing LF weighting function and the use
of medians and means from multiple functional hearing groups provide a
more representative and protective approach for assessing acoustic
impacts on VLF and LF cetaceans. This approach incorporates data from a
broader range of species and avoids overreliance on data from a single
species or functional hearing group. NMFS' approach has remained
consistent throughout our technical guidance development (2016, 2018,
2024), and we have addressed comments on the LF cetacean weighting
function in our previous Federal Register notices finalizing these
documents (81 FR 51693, August 4, 2016; 89 FR 84872, October 24, 2024).
NMFS' 2024 Technical Acoustic Guidance does not incorporate the recent
data on minke whale hearing. However, NMFS has committed to
incorporating this data into future versions, as indicated in our 2024
Updated Technical Guidance. NMFS is awaiting the publication from the
2024 field season to be published and made publicly available before
re-evaluating our acoustic criteria for mysticetes.
Comment 9: A commenter stated that NMFS has relied improperly on
means and medians in establishing its thresholds for auditory impacts
and references a similar comment on the 2024 HCTT Draft EIS/OEIS. In
that comment, the commenter recommends implementation of a 6 dB
reduction to its TTS and PTS thresholds in line with the suggestions by
Tougaard et al. (2015). The commenter states that a 6 dB adjustment
would accord with the minimum level of ``non-trivial'' TTS required to
evaluate onset, effectively adjusting the exposure functions to more
closely match the point where TTS begins.
Response: The technical guidance appropriately uses measures of
central tendency based on an onset level of 6 dB TTS. No reduction is
necessary or supported by the scientific literature, especially
considering numerous other conservative methods in the auditory
criteria. For example, the Navy, and subsequently NMFS, assumes no
recovery of hearing during time intervals between intermittent
exposures. However, multiple studies from humans, terrestrial mammals,
and marine mammals have demonstrated less TTS from intermittent
exposures compared to continuous exposures with the same total energy
because hearing is known to experience some recovery in between noise
exposures. Therefore, the Navy's approach, as relied upon in NMFS'
proposed and final rules, is known to overestimate the effects of
intermittent noise sources such as tactical sonars. Further, marine
mammal TTS data have shown that, for two exposures with equal energy,
the longer duration exposure tends to produce a larger amount of TTS.
Since most marine mammal TTS data have been obtained using exposure
durations up to an hour, much longer than the durations of many
tactical sources, the use of the existing marine mammal TTS data tends
to over-estimate the effects of sonars with shorter duration signals.
Comment 10: A commenter stated that NMFS wholly discounted gas-
bubble pathology as a mechanism of harm to marine mammals due to the
specified activities, and that the Action Proponents must assume that a
number of beaked whales are subject to injury and mortality from gas-
bubble formation.
Response: The commenter's characterization of NMFS' analysis is
incorrect. NMFS does not disregard the fact that it is possible for
naval activities using hull-mounted tactical sonar to contribute to the
death of marine mammals in certain circumstances (that are not present
in the AFTT Study Area) via strandings resulting from behaviorally
mediated physiological impacts or other gas-related injuries. In the
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat section of the proposed rule, NMFS discusses these potential
causes and outlines the few cases where active naval sonar (in the U.S.
or, largely, elsewhere) has either potentially contributed to or, as
with the Bahamas example, been more definitively causally linked with
marine mammal strandings. As noted, there are a suite of factors that
have been associated with these specific cases of strandings directly
associated with sonar (steep bathymetry, multiple hull-mounted
platforms using sonar simultaneously, constricted channels, strong
surface ducts, etc.). These factors are not present together in the
AFTT Study Area during the specified activities (and the Navy takes
care across the world not to operate under these circumstances without
additional monitoring). Further, there have never been any strandings
associated with Navy sonar use in the AFTT Study Area. For these
reasons, NMFS does not anticipate that the Action Proponents' training
or testing activities will result in marine mammal strandings, and none
are authorized. Furthermore, ongoing Navy funded beaked whale
monitoring at a heavily used training and testing area in the SOCAL
Range Complex has not documented mortality or habitat abandonment by
beaked whales. Passive acoustic detections of beaked whales have not
significantly changed over 10 years of monitoring (DiMarzio et al.,
2018; DiMarzio et al., 2019; DiMarzio et al., 2020). From visual
surveys in the area since 2006 there have been repeated sightings of
the same individual beaked whales, beaked whale mother-calf pairs, and
beaked whale mother-calf pairs with mothers on their second calf
(Schorr et al., 2018; Schorr et al., 2020). Satellite tracking studies
of beaked whales documented high site fidelity to this area even though
the
[[Page 50512]]
study area is located in one of the most used Navy areas in the Pacific
(Schorr et al., 2018; Schorr et al., 2020).
Comment 11: A commenter stated that NMFS failed to present a
meaningful analysis of the Navy's aggregate effects on marine mammal
populations and refers to its comment on the 2024 HCTT Draft EIS/OEIS.
Response: The commenter's supporting rationale for their comment is
in reference to the 2024 HCTT Draft EIS/OEIS. While some of the
information considered in the AFTT proposed rule and this final rule is
generally similar, the commenter has not provided recommendations
specific to how NMFS' analysis of the Action Proponents activities in
the proposed rule fails to consider the Action Proponents' aggregate
effects on marine mammal populations. NMFS fully analyzed and
considered the potential for aggregate effects from all of the Action
Proponents' specified activities, and has applied a reasoned and
comprehensive approach to evaluating the effects of these activities on
marine mammal species or stocks and their habitat. This analysis was
detailed in the Preliminary Analysis and Negligible Impact
Determination section of the proposed rule and is repeated here in the
Analysis and Negligible Impact Determination section of the final rule.
Our analysis includes consideration of unusual mortality events
(UMEs) and previous environmental impacts, where appropriate, to inform
the baseline levels of both individual health and susceptibility to
additional stressors, as well as stock status. Further, the species and
stock-specific assessments in the Analysis and Negligible Impact
Determination section (which have been updated and expanded since the
previous AFTT rulemaking to consider additional species- and stock-
specific factors) present and address the combined mortality, injury,
behavioral harassment, and other effects of the aggregate activities,
including impacts anticipated in important habitats such as Endangered
Species Act (ESA)-designated critical habitat and known BIAs (and in
consideration of applicable mitigation), as well as other information
that supports our determinations that the Action Proponents' activities
will not adversely affect any species or stocks via impacts on annual
rates of recruitment or survival. We refer the reader to the Analysis
and Negligible Impact Determination section for this analysis.
Further, widespread, extensive monitoring since 2006 on Navy ranges
that have been used for training and testing for decades has
demonstrated no evidence of population-level impacts (see <a href="https://www.navymarinespeciesmonitoring.us/regions/pacific/current-projects/">https://www.navymarinespeciesmonitoring.us/regions/pacific/current-projects/</a>
for results, e.g., ``Cuvier's Beaked Whale and Fin Whale Population
Dynamics and Impact Assessment at the Southern California Offshore
Antisubmarine Warfare Range (SOAR)''). Based on the best available
research from NMFS and Navy-funded marine mammal studies, there is no
evidence that ``population-level harm'' to marine mammals, including
beaked whales, is occurring in the AFTT Study Area.
Comment 12: The Commission recommended that NMFS work with the Navy
to reprogram NAEMO to implement densities at a post-processing stage so
that densities can be easily revised rather than needing to remodel the
animat-portion of NAEMO when density estimates change. The Commission
states that such an improvement was recommended by Simmons et al.
(2025) to be addressed through modifications to animat seeding and
investigating runs by hearing group within NAEMO.
Response: NMFS concurs that it is appropriate to explore whether
NAEMO can be reprogrammed to implement densities at a post-processing
stage so that densities can be easily revised rather than needing to
remodel the animat-portion of NAEMO when density estimates change. The
Navy has undertaken work in Fiscal Year 2025 to explore standardization
of animat distributions and statistical considerations of applying
species' densities after the NAEMO post-processor to scale results. If
the Navy, in coordination with NMFS, finds that this proves feasible
and appropriate, the Navy hopes to implement this for Phase V.
Comment 13: The Commission recommended that NMFS refrain from using
cut-off distances in conjunction with the Bayesian BRFs and re-estimate
the numbers of marine mammal takes based solely on the Bayesian BRFs
for the final rule.
In a related comment, a commenter stated that NMFS reduces the
Navy's modeled take estimates through the application of cut-off
distances that do not make sense conceptually, that are based on little
or no data from the behavioral response literature, and that contradict
data that are available, including Falcone et al. (2017) and
Melc[oacute]n et al. (2012). The commenter refers to a description of
their concern in a comment on the 2024 HCTT Draft EIS/OEIS, in which
they state that they agree with the Commission's recommendation that
the Navy refrain from using cut-off distances and rely instead on the
take estimates produced through its response functions.
Response: The consideration of proximity (cut-off distances) was
part of the criteria developed in consultation between the Navy and
NMFS, and is appropriate based on the best available science, which
shows that marine mammal responses to sound vary based on both sound
level and distance. Therefore, these cut-off distances were applied
within NAEMO. The derivation of the BRFs and associated cut-off
distances is provided in the revised Criteria and Thresholds Technical
Report.
The Phase IV approach represents a refinement in assessing
potential behavioral impacts. It employs a probability of response
condition for high source level exposures, addressing previous concerns
from the Commission about potentially cutting off responses when the
probability remained above 50 percent. This approach, combined with the
distance cut-off, provides a more nuanced and protective assessment
compared to the Phase III methodology, which relied solely on distance
cut-offs. Therefore, directly comparing Phase III and Phase IV cut-off
distances is not appropriate.
NMFS and the Navy are confident that this combined distance and
probability threshold approach is well-substantiated by available data
and effectively avoids underestimating potential behavioral responses
to acoustic sources.
To clarify, section 3.1.4 (Dose and Contextual Responses) of the
Criteria and Thresholds Technical Report explains that at low received
levels, distance to the sound source factors into the likelihood of a
behavioral response. Although distance was investigated as a covariate
in the Bayesian BRF model, most BRFs to date have used similar source
levels making received level and source-receiver distance tightly
correlated (see section 3.1.9 (Behavioral Cut-off Conditions) of the
Criteria and Thresholds Technical Report). Therefore, including
distance in the BRF model using the available response-received level
data did not improve the BRFs. Still, NMFS and the Navy agree that
distance is an important contextual factor. Since it was not possible
to directly account for distance in the Bayesian model at this time,
the Navy incorporated the behavioral cut-off conditions, beyond which
significant behavioral reactions are assumed to be unlikely. As
described in section 3.1.9 of the Criteria and Thresholds Technical
Report, the distance cut-off conditions were conservatively estimated
based on
[[Page 50513]]
observations from multiple cited studies. Applying the distance cut-off
condition is appropriate to reasonably estimate significant impacts.
In addition, high source level exposures are addressed by also
using a probability of response condition rather than the dual distance
cut-off applied in Phase III. This method was devised in part to
address public comments, including those from the Commission received
in Phase III that were focused on cutting off behavioral responses, in
some cases, where the probability of response was still above 50
percent. The probability of response cut-off condition in Phase IV
allows for prediction of significant impacts beyond the distance cut-
off.
Regarding the studies cited by a commenter, Melc[oacute]n et al.
(2012) found that the probability of recording blue whale ``D calls''
decreased with higher received levels at the high-frequency acoustic
recording package (HARP) buoy averaged over many hours; however, this
study does not provide any information about the distance between the
sound source and any animals and cannot be used to derive cut-off
distances. Falcone et al. (2017) was reviewed by the Navy and discussed
in the Criteria and Threshold Technical Report: ``. . . Falcone et al.
(2017) modeled apparent responses to mid-powered sources out to 50 km
(27 nmi) and responses to high-powered sources at distances as great as
100 km (54 nmi). However, the models were not developed to estimate
distances to response, and care needs to be taken when interpreting the
results in that context.'' Responses at 100 km (54 nmi) were generally
mild, such as a slight (i.e., less than 2 minute) increase in the
duration of shallow dives that was similar to the range of duration
variability found in dives when no mid-frequency active sonar was
present. The inter-deep dive interval duration also increased for both
mid- and high-powered mid-frequency active sonar (MFAS) sources
starting at 100 km (54 nmi); however, the inter-deep dive interval
duration exhibited the strongest increase only within 20 km (10.8 nmi)
of the source.
As described in section 3.1.9 of the Criteria and Thresholds
Technical Report, the cut-off conditions are applied to predict
significant behavioral responses. The data used to inform the BRFs
includes observations beyond 10 km (5.4 nmi) and studies cited in
section 3.1.9 of the Criteria and Thresholds Technical Report. This
includes data on exposures to other sound sources which is informative
when data on exposure to sonars is limited. All the identified
significant behavioral responses that were used to develop the BRFs are
within the cut-offs (either by distance or sound pressure level (SPL)).
Although behavioral responses are predicted beyond the cut-off
conditions, these are not expected to qualify as harassment under the
MMPA as defined for military readiness activities.
NMFS and the Navy acknowledge the Commission's perspective but
maintain that the combined use of cut-off distances and BRFs provides a
more accurate and realistic assessment of potential behavioral impacts,
particularly for military readiness activities. While Tyack and Thomas
(2019) cautioned against using step functions anchored to the 50
percent response level of dose-response curves, the Navy's methodology
does not employ such an approach. Instead, the cut-off distances,
informed by the farthest observed distances of significant behavioral
reactions in the available data (including those exceeding 10 km (5.4
nmi)), serve as a threshold for identifying responses reasonably likely
to qualify as harassment under the MMPA. This approach prevents
underestimating significant impacts while acknowledging that responses
occurring beyond these distances, while possible, are less likely to
reach this level of concern.
The Navy's Phase IV approach, incorporating both BRFs and
scientifically informed cut-off distances, offers a more realistic
assessment of potential behavioral impacts compared to relying solely
on BRFs. This approach balances the statistical probabilities derived
from the BRFs with empirical observations of behavioral responses in
the field. NMFS and the Navy are confident that this combined approach,
while still incorporating conservatism to account for uncertainty, does
not underestimate potential take by Level B harassment under the MMPA
during military readiness activities and provides a more accurate
representation of potential impacts.
NMFS has independently assessed the thresholds used by the Navy to
identify Level B harassment by behavioral disturbance and finds that
they appropriately apply the best available science and it is not
necessary to recalculate take estimates. As the science related to
marine mammal behavior advances, NMFS and the Navy will continue to
refine consideration of contextual factors, such as distance, in its
assessment of behavioral responses.
Comment 14: The Commission continues to maintain that NMFS has not
provided adequate justification for dismissing the possibility that
single underwater detonations can cause a behavioral response, and,
therefore, again recommended that it estimate and authorize takes by
Level B harassment of marine mammals during all explosive activities,
including those that involve single detonations and gunnery exercises
that have several detonations occurring within a few seconds. The
Commission further recommends that NMFS encourage the Navy to invest
resources in conducting BRSs on marine mammals' responses, including
pinniped responses, to underwater detonations for the derivation of
explosive BRFs, or at the very least a source-specific step-function
threshold, noting that the Navy's Living Marine Resources program has
provided funding for a few opportunistic studies involving behavioral
response of cetaceans exposed to underwater detonations.
Response: NMFS acknowledges the possibility that single underwater
detonations (including some multiple explosive events, such as certain
naval gunnery exercises, that may be treated as a single event because
a few explosions occur closely spaced within a very short time (a few
seconds)) can cause a behavioral response. The current take estimate
framework allows for the consideration of animals exhibiting behavioral
disturbance during single explosions as they are counted as ``taken by
Level B harassment'' if they are exposed above the TTS threshold, which
is 5 dB higher than the behavioral harassment threshold for multiple
detonations. We acknowledge in our analysis that individuals exposed
above the TTS threshold may also be harassed by behavioral disruption
and those potential impacts are considered in the Analysis and
Negligible Impact Determination section. Neither NMFS nor the Navy are
aware of evidence to support the assertion that animals will have
multiple significant behavioral responses (i.e., those that would
qualify as take) to temporally and spatially isolated explosions at
received levels below the TTS threshold. However, if any such responses
were to occur, they would be expected to be rare and since separated in
space and time, would most likely result only in isolated startle
responses (i.e., additional behavioral responses would not be expected
to add cumulatively or in severity). Furthermore, these rare responses
would not be expected to occur at received levels below TTS onset.
Thus, they would occur at received levels already bounded by the single
[[Page 50514]]
detonation criteria (i.e., TTS is used as the Level B harassment
criteria for single detonations) and would therefore already be
accounted for in the current take estimates.
The derivation of the explosive injury criteria is provided in the
Criteria and Thresholds Technical Report. There is limited information
upon which to estimate behavioral response thresholds specific to
explosives. Therefore, as described in the Criteria and Thresholds
Technical Report, the behaviors exhibited by animals exposed to brief
intense tones in the Schlundt et al. (2000) study continue to inform
the behavioral response threshold for explosives. Some of the observed
behaviors in that study would be considered moderate severity for
captive animals with trained behaviors and thus may be potentially
significant in the context of wild animals. Appropriate threshold
metrics are applied for this criterion given the supporting data.
Additionally, RMS SPLs are not a preferred metric for explosives due to
the challenge of identifying the appropriate time window.
Most explosive activities, including all explosive gunnery
activities, analyzed in the rule and the 2025 AFTT SEIS/OEIS include
multiple detonations. For these activities, significant behavioral
responses are assumed to occur if the cumulative SELs are greater than
or equal to 5 dB less than the threshold for onset of TTS. For single
detonations, the analysis in appendix E of the 2025 AFTT Supplemental
EIS/OEIS assumes that any auditory impact (TTS or AUD INJ) may have a
concurrent significant behavioral response. This assumption for single
detonations has been clarified in the revised Criteria and Thresholds
Technical Report.
BRSs on marine mammal responses to underwater detonations would
support future analyses, and NMFS will consider such a recommendation
to Navy relative to other new and ongoing research priorities. The Navy
supports a wide range of research to inform the development of
criteria. The Navy is supporting new research into marine mammal
behavioral responses to detonations through its Living Marine Resources
program (<a href="https://exwc.navfac.navy.mil/Products-and-Services/Environmental-Security/LMR/">https://exwc.navfac.navy.mil/Products-and-Services/Environmental-Security/LMR/</a>). The findings of this research will be
incorporated into the behavioral response criteria when available. To
clarify, the Navy has specifically monitored shock trial detonations
since the 1990s. Madhusudhana et al. (2024) present data on pre- and
post-detonation vocalizations at monitoring sites in the vicinity of
the 2021 full ship shock trial. Most sites showed no significant
changes in vocalization activity for the timeframes analyzed.
Mitigation and Monitoring
Comment 15: The Commission strongly recommended that NMFS require
the Navy to use passive acoustic monitoring (PAM) prior to and during
activities involving ship shock trials in the final rule, consistent
with explosive sonobuoys, explosive torpedoes, and sinking exercises.
The Commission notes that since mission effectiveness would not be
impacted, the measures are considered practicable, and their
implementation would reduce the potential for the most lethal marine
mammal impacts.
Response: As detailed in table 38, the time and location of ship
shock trials are chosen specifically to avoid impacts to large whales
and, further, Naval Sea Systems Command (NAVSEA) will develop an
extensive mitigation plan for NMFS review and concurrence prior to a
ship shock trial. While use of sonobuoys would not affect the ship
shock trial, PAM from a 2001 ship shock trial for the Churchill full
ship shock trial indicated limited efficacy of the PAM (Clarke and
Norman, 2005). As such, and given the significant expense associated
with implementing PAM for ship shock trials, NMFS is not requiring the
Navy to conduct PAM prior to and during ship shock trials.
Comment 16: The Commission strongly recommended that NMFS require
the Navy to use passive acoustic devices (i.e., directional frequency
analysis and recording (DIFAR) and other types of passive sonobuoys,
operational hydrophones) prior to explosive bombing exercises and air-
to-surface and surface-to-surface explosive missile and rocket
exercises to detect marine mammals and implement the necessary
mitigation measures in the final rule.
Response: The Navy employs PAM to supplement visual monitoring when
practicable to do so (i.e., when assets that have PAM capabilities are
already participating in the activity). For explosive events in which
there are no platforms participating that have PAM capabilities, adding
PAM capability for mitigation, either by adding a PAM device (e.g.,
hydrophone) to a platform already participating in the activity or by
adding a platform with integrated PAM capabilities to the activity
(e.g., a sonobuoy), is not practicable.
The type of aircraft that conduct these bombing, missile, and
rocket exercises do not have the capability to deploy and employ
sonobuoys. The Action Proponents state that diverting platforms that
have PAM capabilities would impact their ability to meet their Title 10
requirements and reduce the service life of those systems. The Action
Proponents additionally state that there are significant manpower and
logistical constraints that make constructing and maintaining
additional PAM systems or platforms for additional training and testing
activities impracticable. Given the impracticality of such a measure,
NMFS has found that this measure is not warranted, and it is not
required in this final rule.
Comment 17: The Commission recommended that NMFS prohibit
detonation of explosive sonobuoys within 3 nmi (5.6 km) of the
Southeast North Atlantic Right Whale Mitigation Area from 15 November
through 15 April and the Rice's Whale Mitigation Area year-round in the
final rule consistent with the Northeast North Atlantic Right Whale
Mitigation Area.
Response: NMFS concurs with the Commission's recommendation, and
the Action Proponents have indicated that such a measure is
practicable. Therefore, this final rule includes requirements that
prohibit detonation of explosive sonobuoys within 3 nmi (5.6 km) of the
Southeast North Atlantic Right Whale Mitigation Area from 15 November
through 15 April and in the Rice's Whale Mitigation Area year-round.
Comment 18: The Commission recommended that NMFS require the Navy
to use its instrumented ranges and sonobuoys to localize marine mammals
and implement the relevant mitigation measures during active acoustic
events and to take a harder look at the technologies that the Canadian
Department of National Defense (DND) uses during its at-sea activities
and incorporate those technologies accordingly for other Phase IV LOA
applications. The Commission cites the Lookout Effectiveness Study
(Oedekoven and Thomas, 2022) in support of its recommendation. In a
related comment, a commenter stated that to maximize the probability of
detecting one or more North Atlantic right whales (NARWs) and further
reduce risk to the species, the Action Proponents should use both
visual observations and passive acoustic detections to inform
mitigation decisions and raise the awareness of Lookouts.
Response: The Action Proponents intend to continue to use PAM prior
to activities involving explosive sonobuoys and explosive torpedoes,
and during sinking exercises (SINKEX). During the use of active
acoustics, Navy assets with
[[Page 50515]]
PAM capabilities (e.g., sonobuoys) that are already participating in an
activity will continue to monitor for marine mammals, as described in
section 5.6 (Activity-based Mitigations) of the 2025 AFTT Supplemental
EIS/OEIS. However, the fluidity and nature of military readiness
activities (e.g., fast-paced and mobile readiness evolutions), as well
as the limitations of these monitoring capabilities, make it
impractical for passive acoustic devices to be used as precise real-
time indicators of marine mammal location for mitigation (e.g., active
sonar power downs or shutdowns, ceasing use of explosives) without an
accompanying visual sighting. While we acknowledge that the Lookout
Effectiveness Study suggests that detection of marine mammals is less
certain than previously assumed at certain distances, we disagree with
the assertion that the use of Lookouts has been shown to be wholly
ineffective. Lookouts remain an important component of the Action
Proponents' mitigation strategy, especially as it relates to minimizing
exposure to the more harmful impacts that may occur within closer
proximity to the source, where Lookouts are most effective. Further,
this final rule requires that in the Northeast North Atlantic Right
Whale Mitigation Area and the Dynamic North Atlantic Right Whale
Mitigation Area, the Action Proponents must provide the WhaleMap web
address (<a href="https://whalemap.org">https://whalemap.org</a>) and advise that risk of whale strike is
increased: (1) after observing a NARW; (2) when operating within 5 nmi
(9.3 km) of a known sighting reported within the past 24 hours; (3)
within a NMFS-designated Seasonal Management Area, Dynamic Management
Area, or Slow Zone; and (4) when transiting at night or during periods
of reduced visibility. This final rule also requires that sightings
data must be used when planning propulsion testing event details (e.g.,
timing, location, duration) in the Dynamic North Atlantic Right Whale
Mitigation Area to minimize impacts to NARW to the maximum extent
practical, and during propulsion testing, to the maximum extent
practical, Lookouts must be provided recent WhaleMap (<a href="https://whalemap.org/">https://whalemap.org/</a>) sightings data to help inform visual observations. Last,
in the Northeast North Atlantic Right Whale Mitigation Area, the Action
Proponents must conduct a web query or email inquiry to the North
Atlantic Right Whale Sighting Advisory System or WhaleMap (<a href="https://whalemap.org/">https://whalemap.org/</a>) to obtain the latest NARW sightings data prior to
transiting the mitigation area. The Action Proponents must provide the
sightings data to Lookouts prior to them standing watch. Lookouts must
use that data to help inform visual observations during vessel
transits.
In the AFTT Study Area, a small subset of Navy training and testing
takes place on the only instrumented range within the study area. The
Navy's instrumented ranges do not have the capabilities to be used
effectively for mitigation (see section 5.5.3 (Active and Passive
Acoustic Monitoring Devices) of the 2018 AFTT EIS/OEIS). As such, NMFS
disagrees with the Commission's assertion that real time localization
of marine mammals using the Navy's instrumented ranges and sonobuoys is
an appropriate requirement, beyond what the Action Proponents are
currently doing.
The Action Proponents and NMFS have considered and will continue to
study the Canadian DND project, including the technologies used during
at-sea activities; however, NMFS disagrees that such a requirement is
warranted in this final rule. As more information from the Canadian DND
project becomes available, the Action Proponents and NMFS may
reconsider whether additional requirements are needed.
Comment 19: The Commission recommends that the NMFS final rule
require the Action Proponents to follow established incident reporting
procedures and halt any active acoustic, explosive, pile-driving, or
air gun activity if a marine mammal is injured or killed during or
immediately after the activity and require the Action Proponents to
consult with NMFS to review or adapt the mitigation measures, as
necessary.
Response: The proposed rule and this final rule include a
requirement for the Action Proponents to follow established incident
reporting procedures if the specified activity is thought to have
resulted in the mortality or serious injury of any marine mammals, as
recommended by the Commission as outlined in the Notification and
Reporting Plan. Note that the Notification and Reporting Plan also
requires the Action Proponents to follow established incident reporting
protocols for cetacean live strandings. Regarding the Commission's
recommendation to require that the Action Proponents halt any active
acoustic, explosive, pile driving, or air gun activity if a marine
mammal is injured or killed during or immediately after the activity,
and require the Action Proponents to consult with NMFS to review or
adapt the mitigation measures, as necessary, NMFS agrees with the
recommendation to suspend the use of explosives in an event if a marine
mammal is injured or killed during or immediately after the activity.
Neither NMFS nor the Action Proponents anticipate serious injury or
mortality from any activity other than the use of explosives or vessel
movement. For all activities involving explosives, the final rule
expressly requires that, if a marine mammal is visibly injured or
killed as a result of detonation, use of explosives in the event must
be suspended immediately (see Mitigation Measures section). While
similar language is not included for active acoustics, pile driving,
and air gun activity, the proposed rule and this final rule require the
Action Proponents to power down or shut down these sources if a marine
mammal is observed within the applicable mitigation zone. The Action
Proponents will also continue to follow incident reporting procedures
(including for vessel strike, should it occur) and consult with NMFS to
review or adapt the mitigation measures, as necessary, through the
adaptive management process.
Comment 20: The Commission recommended that NMFS--
<bullet> Clearly separate its application of the least practicable
adverse impact requirement from its negligible impact determination;
<bullet> Adopt a clear decision-making framework that recognizes
the species and stock component and the marine mammal habitat component
of the least practicable adverse impact provision and always consider
whether there are potentially adverse impacts on marine mammal habitat
and whether it is practicable to minimize them;
<bullet> Rework its evaluation criteria for applying the least
practicable adverse impact standard to separate the factors used to
determine whether a potential impact on marine mammals or their habitat
is adverse and whether possible mitigation measures would be effective;
<bullet> Address these concerns by adopting a simple, two-step
analysis that more closely tracks the statutory provisions being
implemented and, if NMFS is using some other legal standard to
implement the least practicable adverse impact requirements, provide a
clear and concise description of that standard and explain why it
believes it to be ``sufficient'' to meet the statutory legal
requirements; and
<bullet> Apply these basic steps and criteria consistently for
least practicable adverse impact determinations across incidental take
authorizations.
The Commission references previous letters in which it has included
its
[[Page 50516]]
complete rationale for these recommendations.
Response: NMFS has made clear in this and other rules that the
agency separates its application of the least practicable adverse
impact requirement in the Mitigation Measures section from its
negligible impact analyses and determinations for each species or stock
in the Analysis and Negligible Impact Determination section. Further,
NMFS has made this separation clear in practice for years by requiring
mitigation measures to reduce impacts to marine mammal species and
stocks and their habitat for all projects, even those for which the
anticipated take would clearly have a negligible impact, even in the
absence of mitigation.
In the Mitigation Measures section of this rule, NMFS has explained
in detail our interpretation of the least practicable adverse impact
standard, the rationale for our interpretation, and how we implement
the standard. The method the agency uses addresses all of the necessary
components of the standard and produces effective mitigation measures
that result in the least practicable adverse impact on both the species
or stocks and their habitat. The commenter has failed to illustrate why
NMFS' approach is inadequate or why the commenter's proposed approach
would be better, and we therefore decline to accept the recommendation.
Also in the Mitigation Measures section, NMFS has explained in
detail our application of the least practicable adverse impact
standard. The commenter has recommended an alternate way of
interpreting and implementing the least practicable adverse impact
standard, in which NMFS would consider the effectiveness of a measure
in our evaluation of its practicability. The commenter erroneously
asserts that NMFS currently considers the effectiveness of a measure in
a determination of whether the potential effects of an activity are
adverse, but the commenter has misunderstood NMFS' application of the
standard--rather, NMFS appropriately considers the effectiveness of a
measure in the evaluation of the degree to which a measure will reduce
adverse impacts on marine mammal species or stocks and their habitat,
as a less effective measure will less successfully reduce these impacts
on marine mammals. Further, the commenter has not provided information
that shows that their proposed approach would more successfully
evaluate mitigation under the least practicable adverse impact
standard, and we decline to accept it.
Further, NMFS disagrees with the commenter's assertion that
analysis of the rule's mitigation measures under the least practicable
adverse impact standard remains unclear or that the suggested
shortcomings exist. The commenter provides no rationale as to why the
two-step process they describe is better than the process that NMFS
uses to evaluate the least practicable adverse impact that is described
in the rule, and therefore we decline to accept the recommendation.
Regarding the assertion that the standard shifts on a case-by-case
basis, the commenter misunderstands NMFS' process. Neither the least
practicable adverse impact standard nor NMFS' process for evaluating it
shifts on a case-by-case basis. Rather, as the commenter suggests
should be the case, the evaluation itself is case-specific to the
proposed activity, the predicted impacts, and the mitigation under
consideration.
Regarding the recommendation to apply the recommended steps and
criteria for least practicable adverse impact determinations across
incidental take authorizations, as outlined above, NMFS disagrees with
these recommendations and therefore does not intend to apply them
across incidental take authorizations.
Comment 21: A commenter stated that to adequately protect NARW, the
boundaries of the Southeast North Atlantic Right Whale Mitigation Area,
and its requirements, should be extended north to Cape Fear, North
Carolina. The commenter said this extension would limit the use of
active sonar, prohibit in-water explosives and non-explosive ordnance,
and impose several measures to reduce the risk of vessel strike in the
entirety of the species' calving habitat from November 15 to April 15,
reflecting the duration of the calving season.
Response: Expansion of the Southeast North Atlantic Right Whale
Mitigation Area northward to encompass all areas of potential
occurrence would require training activities to move farther north or
farther out to sea, which the Action Proponents indicate is
impracticable due to implications for safety and sustainability, as
detailed in section 5.4.3 (Mitigation Areas off the Mid-Atlantic and
Southeastern United States) of the 2018 AFTT Final EIS/OEIS.
Additionally, that section explains why further limitations on
activities, including limitations on active sonar, in-water explosives
and non-explosive ordnance, and imposition of additional measures to
reduce the risk of vessel strike, within this area would be
impracticable. NMFS reviewed and concurs with the Action Proponents'
assessment of practicability, effects on mission effectiveness, and
personnel safety, and as such, has not required expansion of the
Southeast North Atlantic Right Whale Mitigation Area beyond that
included in the proposed rule.
The best available density data for the AFTT Study Area shows that
the Southeast North Atlantic Right Whale Mitigation Area encompasses
the areas of highest density in the region (Roberts et al., 2023; U.S.
Department of the Navy, 2025). Although NARW have been sighted on rare
occasions east of the mitigation area, these animals were located
outside of the higher use habitats that represent the primary
occurrence of the population. Overall, most NARW sightings made during
Navy and NMFS surveys have occurred in, or very close to, the Southeast
North Atlantic Right Whale Mitigation Area, which further indicates
that the mitigation area may have the highest seasonal abundance of
NARW in waters off the mid-Atlantic and southeastern United States.
Though the spatial extent of the Southeast North Atlantic Right
Whale Mitigation Area cannot be extended, this final rule includes
additional mitigations in that area and in the Dynamic North Atlantic
Right Whale Mitigation Area, which encompasses the U.S. Exclusive
Economic Zone (EEZ) off the East Coast. In the Southeast North Atlantic
Right Whale Mitigation Area, this final rule includes two new
requirements. First, from November 15 to April 15, the Action
Proponents must not detonate explosive sonobuoys within 3 nmi (5.6 km)
of the Southeast North Atlantic Right Whale Mitigation Area. Second,
during the same time period, the Action Proponents must not conduct
vessel propulsion testing. In the Dynamic North Atlantic Right Whale
Mitigation Area, in Protective Measures Assessment Protocol (PMAP)-
generated reports, Action Proponents will provide the WhaleMap web
address (<a href="https://whalemap.org">https://whalemap.org</a>); advise that risk of whale strike is
increased after observing a NARW; when operating within 5 nmi (9.3 km)
of a known sighting reported within the past 24 hours; within a NMFS-
designated Seasonal Management Area, Dynamic Management Area, or Slow
Zone; and when transiting at night or during periods of reduced
visibility; and reinforce the requirement of the International
Regulations for Preventing Collisions at Sea (COLREGS) for vessels to
proceed at a safe speed, appropriate to the prevailing circumstances
and conditions, to avoid a collision with any
[[Page 50517]]
sighted object or disturbance, including any marine mammal.
Additionally, during propulsion testing in the mitigation area, to the
maximum extent practical, Lookouts will be provided recent <a href="https://www.whalemap.org">https://www.whalemap.org</a> sightings data to help inform visual observations.
Further, this final rule requires that within the first year of
AFTT Phase IV implementation, the Action Proponents must work
collaboratively with the NMFS ESA Interagency Cooperation Division and
the NMFS Permits and Conservation Division to: (1) analyze and discuss
the application of new information from the NMFS North Atlantic Right
Whale Persistence Modelling Efforts toward AFTT mitigation measures;
(2) evaluate the practicability and conservation benefits of newly
proposed mitigation measures and/or changes to existing measures based
on information from the model; and (3) implement any new mitigation
measures or changes to existing measures that meet the Action
Proponents' Practicability Criteria and Sufficiently Beneficial
requirements.
Comment 22: The Commission stated that under the Gulf biological
opinion (commonly referred to as BiOp) for oil and gas activities, the
Bureau of Ocean Energy Management (BOEM) and the Bureau of
Environmental Safety and Enforcement (BSEE) would be required to
identify a near real-time platform (e.g., WhaleAlert) to help oil- and
gas-related vessels avoid strikes of Rice's whales. BOEM and BSEE, in
collaboration with NMFS, also must work to ensure additional devices
and near real-time detection data systems are integrated into the near
real-time sightings platform to establish an integrated platform for
all Rice's whale detections in the Gulf (e.g., WhaleMap). The
Commission recommends that NMFS require the Action Proponents to
conduct a query of the aforementioned platform (e.g., WhaleAlert,
WhaleMap) that houses the Rice's whale sightings once it is established
and prior to transiting the Rice's Whale Mitigation Area, provide those
sightings data to the Lookouts prior to them standing watch, use the
data to inform the Lookouts' visual observations during vessel
transits, and implement speed reductions to 10 knots (kn) (18.5 km/hr)
for surface ships transiting within 5 nmi (9.3 km) of a sighting
reported in the platform within the previous 24 hours. Any
modifications to the mitigation requirements for the Rice's Whale
Mitigation Area can be addressed during the Navy's Annual Adaptive
Management Meetings.
In a related comment, a commenter stated that protections must be
afforded to Rice's whale throughout the entirety of their known
habitat, and that NMFS and the Action Proponents should revise the
boundaries of the Rice's Whale Mitigation Area westwards to include all
U.S. waters between the 100-m and 400-m isobaths, to reflect best
available scientific information on the species. The commenter also
recommended that the requirements in the Rice's Whale Mitigation Area
be expanded to include the following mitigation requirements that
emulate a subset of those required for NARW in other proposed
mitigation areas. The commenter stated that the recommendations account
for the fact that an Early Warning System for Rice's whales does not
yet exist. These include:
(1) Year-round within the mitigation area, surface ships must
minimize transits and transit distances through Rice's whale habitat to
the maximum extent practicable, and must implement speed reductions:
(a) after they observe a Rice's whale, if they are within 5 nmi (9.3
km) of a sighting of a Rice's whale reported in the previous 12 hours,
and (b) at minimum, at night and in restricted visibility; and
(2) The Action Proponents must provide Lookouts the sightings data
prior to standing watch to help inform visual observations.
Response: This rulemaking includes a Rice's Whale Mitigation Area
that overlaps the Rice's whale small and resident population area
identified by NMFS in its 2016 status review (Rosel et al., 2016) and
most of the eastern portion of proposed critical habitat (88 FR 47453,
July 24, 2023). Within this area, the Action Proponents must not use
more than 200 hours of surface ship hull-mounted MFAS annually and must
not detonate in-water explosives (including underwater explosives and
explosives deployed against surface targets) except during mine warfare
activities. Additionally, the Ship Shock Trial Mitigation Area would
ensure that the northern Gulf of America ship shock trial box is
situated outside of the Rice's whale core distribution area identified
in 2019 (84 FR 15446, April 15, 2019). These restrictions will reduce
the severity of impacts to Rice's whales by reducing their exposure to
levels of sound from sonar or explosives that would have the potential
to cause injury or mortality, thereby further supporting NMFS'
determination that non-auditory injury and mortality are not expected
to occur, reducing the likelihood of auditory injury, and, further,
minimizing the severity of behavioral disturbance. Further, as
described in the Changes from the Proposed Rule to the Final Rule
section of this final rule, we have added three new measures in the
Rice's Whale Mitigation Area since publication of the proposed rule.
This final rule includes a requirement that the Action Proponents must
not detonate explosive sonobuoys within 3 nmi (5.6 km) of the Rice's
Whale Mitigation Area as well as two new measures to further reduce the
risk of vessel strike of Rice's whale. The Action Proponents must avoid
conducting vessel propulsion testing events in the Rice's Whale
Mitigation Area to the maximum extent practical and the Action
Proponents must issue an annual awareness message to Navy vessels that
routinely train or test in the vicinity of the Rice's whale proposed
critical habitat and Coast Guard vessels that routinely train anywhere
in the Gulf of America.
While it is not practicable for the Action Proponents to issue
speed restrictions (see section 5 (Mitigation Considered but
Eliminated) of the 2025 AFTT SEIS/OEIS), as suggested by the commenter,
this annual awareness message will advise that risk of whale strike is
increased when transiting through Rice's whale proposed critical
habitat (i.e., within the 100 to 400 m isobaths), particularly at night
or during periods of reduced visibility, and reinforce the requirement
of the COLREGS (<a href="https://www.imo.org/en/about/conventions/pages/colreg.aspx">https://www.imo.org/en/about/conventions/pages/colreg.aspx</a>) for vessels to proceed at a safe speed, appropriate for
the prevailing circumstances and conditions, to avoid a collision with
any sighted object or disturbance, including any marine mammal.
Regarding the recommendation for surface ships to minimize transits
and transit distances through Rice's whale habitat to the maximum
extent practicable, Navy asserts that it does not have many training
events in the area, and vessel traffic in the area is already limited.
As such, transits through this area are already minimized, as
recommended by the commenter.
Regarding the commenter's recommendation to revise the boundaries
of the Rice's Whale Mitigation Area westwards to include all U.S.
waters between the 100-m and 400-m isobaths, the majority of the Navy's
activities do not occur within the central/western portion of Rice's
whale habitat. The potential for impacts in that area is very low due
to infrequent use of Navy surface ship hull-mounted MFAS or explosives
in the central/western portion of the habitat. The Coast Guard does
train in this area but
[[Page 50518]]
their training activities do not include the use of sonar and other
transducers or explosives (of note, the Coast Guard is not planning any
testing activities as part of the specified activity in the AFTT Study
Area). As such, the only applicable mitigation requirement for the
waters west of the Rice's Whale Mitigation Area between the 100-m and
400-m isobaths is for the Action Proponents to issue an annual
awareness message to Navy vessels that routinely train or test in the
vicinity of the Rice's whale proposed critical habitat and for the
Coast Guard to send the awareness messages required in the Rice's Whale
Mitigation Area to all Coast Guard vessels that routinely train
anywhere in the Gulf of America, and this final rule includes a
requirement for the Action Proponents to do so.
Regarding the Commission's recommendation related to a future
Rice's whale sightings platform (e.g., WhaleAlert, WhaleMap), when such
a platform is established, NMFS and the Action Proponents will evaluate
its potential use for mitigating potential impacts to Rice's whale,
including providing sightings data to the Lookouts prior to them
standing watch, use of the data to inform the Lookouts' visual
observations during vessel transits, and potential speed restrictions
in a defined time and area relative to sightings. In the public comment
related to the Commission's, the commenter stated that its
recommendations account for the fact that an Early Warning System for
Rice's whale does not yet exist, but it is unclear what the commenter
is referring to regarding providing Lookouts the sightings data prior
to standing watch to help inform visual observations absent a sighting
platform such as WhaleMap, and as such, this final rule does not
incorporate this recommendation.
Comment 23: A commenter stated that while it provisionally supports
aspects of the proposed rule, the least practicable adverse impact
standard has not yet been met. The commenter provided specific
mitigation recommendations in support of their assertion.
Response: NMFS has described our well-reasoned process for
identifying the measures needed to meet the least practicable adverse
impact standard in the Mitigation Measures section in this rule, and we
have followed the approach described there when analyzing potential
mitigation for the Action Proponents' activities in the AFTT Study
Area. Responses to specific recommendations for mitigation measures
provided by the commenters are discussed separately.
Comment 24: A commenter recommended that NMFS incorporate new
scientific information into design of its mitigation areas,
specifically referencing Houser et al. (2024) and Southall et al.
(2024). The commenter recommended that NMFS use the data to inform
which types of acoustic sources to limit in mitigation areas important
to particular species, and the size of the stand-off distances to apply
to those areas.
Response: The mitigation measures in this rule are informed by
multiple factors, including the sensitivity of certain hearing groups
to certain sound sources (informed by the Phase IV criteria and
thresholds) and vulnerability to other threats (e.g., vessel strike).
The Phase IV criteria and thresholds incorporate data from Houser et
al. (2024), and as such, the mitigation areas in the proposed rule and
final rule inherently consider those data. While the Phase IV criteria
and thresholds do not incorporate data from Southall et al. (2024),
they include delphinid response data from other studies, and the
potential responses observed in Southall et al. (2024) occurred at
received levels and distances assessed for potentially significant
behavioral responses in the AFTT analysis. The commenter did not
provide specific mitigation recommendations that may stem from the
publications they reference. However, NMFS has responded to other
mitigation recommendations from the commenter in separate responses
herein and has explained that it has determined that the Action
Proponents' planned mitigation measures would effect the least
practicable adverse impact on the affected species and their habitat.
Comment 25: A commenter stated that the proposed measure to
minimize the use of helicopter dipping sonar to the maximum extent
practicable in the Southeast North Atlantic Right Whale Mitigation Area
is a step toward mitigation of impacts from dipping sonar. However, the
commenter states that the available scientific evidence on the impacts
of dipping sonar on deep-dive rates in beaked whales (family
Ziphiidae), indicates that management of this acoustic source should be
expanded, including to areas within the AFTT Study Area representing
important habitat for beaked whale populations.
Response: As stated in the Analysis and Negligible Impact
Determination section of the proposed rule and this final rule, there
are no known BIAs for beaked whales in the AFTT Study Area, though
these stocks generally occur in higher densities year-round in deep
waters over the Atlantic continental shelf margins. The Western North
Atlantic stocks of goose-beaked whales and Blainville's beaked whales
generally congregate over continental shelf margins from Canada to
North Carolina, with goose-beaked whales reported as far south as the
Caribbean and Blainville's beaked whales as far south as the Bahamas.
The Western North Atlantic stock of Gervais' beaked whales generally
congregate over continental shelf margins from New York to North
Carolina. The Western North Atlantic stock of Sowerby's beaked whales
is the most northerly distributed stock of deep-diving mesoplodonts,
and they generally congregate over continental shelf margins from
Labrador to Massachusetts. The Western North Atlantic stock of True's
beaked whales generally congregate over continental shelf margins from
Nova Scotia to Cape Hatteras, with northern occurrence likely relating
to the Gulf Stream. The Western North Atlantic stock of northern
bottlenose whales is uncommon in U.S. waters and generally congregates
in areas of high relief, including shelf breaks and submarine canyons
from the Davis Strait to New England, although strandings have occurred
as far south as North Carolina.
The commenter provided a general recommendation for expansion of
dipping sonar mitigation in important habitat for beaked whales but did
not specify particular areas or beaked whale species to prioritize for
such mitigation. As noted above, while beaked whales generally occur in
higher densities year-round in deep waters over the Atlantic
continental shelf margins, the latitudinal ranges vary depending on the
species. If the entire shelf break were considered important habitat
for beaked whales, that would limit the bathymetric scope of areas
available for the training and testing of dipping sonar and would not
be practical.
As the commenter notes, the proposed rule and this final rule
include a Southeast North Atlantic Right Whale Mitigation Area in which
the Action Proponents must minimize the use of helicopter dipping sonar
to the maximum extent practical. This measure would benefit the Western
North Atlantic stocks of goose-beaked whales and Blainville's beaked
whales in the most southern portion of their range. The proposed rule
and this final rule also include Major Training Exercise Planning
Awareness Mitigation Areas across multiple areas along the Atlantic
continental shelf break in which the Action Proponents must either
limit major training exercises
[[Page 50519]]
(MTEs) or not conduct MTEs. These restrictions would benefit multiple
beaked whale species, and would inherently limit or prohibit dipping
sonar, as the majority of dipping sonar used during training activities
in the mid-Atlantic is used during MTEs (unit-level training mostly
occurs in the Jacksonville Operating Area (OPAREA)). Also of note, the
Action Proponents already do not conduct much sonar in some beaked
whale habitats, such as the Cape Hatteras area where goose-beaked
whales are known to occur. This location was chosen for the Atlantic
BRS on beaked whales specifically because those beaked whales are not
frequently exposed to mid-frequency active sonar. Additional
restrictions on the use of dipping sonar in the Atlantic is not
practicable, and as such, is not required by this final rule.
Comment 26: A commenter stated that, to reflect the best available
scientific information and achieve the least practicable adverse impact
to NARW, the boundaries of the Northeast North Atlantic Right Whale
Mitigation Area should be extended to include the established foraging
habitat south of Martha's Vineyard and Nantucket, Massachusetts.
Response: NMFS concurs with the commenter that additional
mitigation is warranted in the NARW feeding area south of Martha's
Vineyard and Nantucket. As such, this final rule includes a new
Martha's Vineyard North Atlantic Right Whale Mitigation Area in which
the Action Proponents must avoid conducting vessel propulsion testing
events to the maximum extent practical. In addition to the new Martha's
Vineyard North Atlantic Right Whale Mitigation Area, this final rule
includes multiple new mitigation measures for NARW, as described in
response to Comment 21, including new measures in the Dynamic North
Atlantic Right Whale Mitigation Area, which overlaps the new Martha's
Vineyard North Atlantic Right Whale Mitigation Area. In this area, the
Action Proponents will provide North Atlantic Right Whale Dynamic
Management Area information (e.g., location and dates) to applicable
assets transiting and training or testing in the vicinity of the
Dynamic Management Area. Further, in PMAP reports generated in the
Dynamic North Atlantic Right Whale Mitigation Area, Action Proponents
will provide the WhaleMap web address (<a href="https://www.whalemap.org">https://www.whalemap.org</a>),
advise situations in which risk of vessel strike is increased, and
reinforce the requirement for vessels to proceed at a safe speed.
Additional details on the above can be found in the response to Comment
21. Additionally, in the Dynamic North Atlantic Right Whale Mitigation
Area, during propulsion testing in the mitigation area, to the maximum
extent practical, Lookouts will be provided recent <a href="https://www.whalemap.org">https://www.whalemap.org</a> sightings data to help inform visual observations.
Further, the Action Proponents follow NARW sighting and avoidance
measures regardless of location, including one or more Lookouts on
manned underway surface vessels in accordance with the most recent
navigation safety instruction and underway manned surface vessels
maneuver themselves (which may include reducing speed) to maintain 500
yd (457.2 m) distance from whales, as mission and circumstances allow.
Within the northeast portion of the Study Area, the Northeast North
Atlantic Right Whale Mitigation Area represents the largest area that
is practical for the Navy to implement that full suite of mitigation.
As such, this final rule does not require that the Action Proponents
extend the boundary of the Northeast North Atlantic Right Whale
Mitigation Area (and the mitigation required in that area) south of
Martha's Vineyard and Nantucket for the reasons described below.
Expanding the full suite of mitigation measures of the Northeast North
Atlantic Right Whale Mitigation Area to the area south of Nantucket and
Martha's Vineyard would encroach upon the primary water space where
training and testing activities are planned to occur. Such
modifications of training and testing activities would have a
significant impact on safety, sustainability, and the Navy's ability to
meet its mission requirements.
The Navy does not typically schedule MTEs in the Northeast Range
Complexes, though MTEs originally planned for other locations may have
to change during an exercise, or in exercise planning, based on an
assessment of the performance of the units, or due to other conditions
such as weather and mechanical issues. These contingency requirements
preclude the Navy from completely eliminating MTEs from occurring in
this area. For training and testing that does occur here, this area
provides a wide range of bathymetric and topographic opportunities that
support critical smaller scale training and testing necessary to meet
mission requirements.
The area is important to the Navy's acoustic and oceanographic
research. Specifically, having access to waterspace within 20 nmi (37
km) of Woods Hole Oceanographic Institute and in the vicinity of the
New England Mud Patch is important to these research activities.
Restricting the area would result in a reduced ability to conduct
accurate oceanographic or acoustic research to meet research
objectives, validate acoustic models, and conduct accurate engineering
tests of acoustic sources, signal processing algorithms, and acoustic
interactions.
Additionally, NAVSEA needs full access and flexibility to conduct
testing in this area. Testing locations are typically located near
systems command support facilities, which provide critical safety,
platform, and infrastructure support and technical expertise necessary
to conduct testing. Restricting the area would result in: (1) reduced
ability to ensure the safety, functionality, and accuracy of systems,
platforms, and components through maintenance, repairs, or testing
prior to use at sea as needed or required by acquisition milestones,
and (2) reduced ability to effectively test systems, platforms, and
components before full-scale production or delivery in order to
validate whether they perform as expected and determine whether they
are operationally effective, suitable, survivable, and safe for their
intended use by the fleet.
Comment 27: A commenter recommended further research and
exploration of the feasibility of signal modification, including
converting upsweeps to downsweeps, reducing the level of the side
bands, or lengthening the rise time. The 2024 AFTT Draft Supplemental
EIS/OEIS considered, but rejected, modification of active sonar sources
for training as part of a potential mitigation measure (``26. Reducing
annual active sonar hours, replacing active sonar, with passive sonar
or modifying active sonar sources for training''), deeming it
impractical for achieving the mission. The commenter stated that the
rationale provided in the 2024 AFTT Draft Supplemental EIS/OEIS does
not clearly justify why signal modifications alone would be
impractical. The commenter states that some of those modifications,
such as converting up-sweeps to down-sweeps, would not alter the
system's spectral output in any way. The commenter stated that it
believes source modification requires greater validation across species
and in more behavioral contexts before any decisions are made to alter
signals--but, given the preliminary data, and given the potential of
this measure to reduce the instances and severity of behavioral
harassment, it urges NMFS to require or otherwise stimulate
investigation of this potentially significant mitigation measure and
provide a schedule for completion.
[[Page 50520]]
Another commenter stated that NMFS and Navy should prioritize
identifying and implementing alternative training methods,
technologies, and locations that do not place vulnerable marine life at
such extreme risk, stating that this would not only fulfill legal
obligations, but also demonstrate a commitment to sustainable
stewardship of our ocean ecosystems.
Response: Active sonar signals are designed explicitly to provide
optimum performance at detecting underwater objects (e.g., submarines)
in a variety of acoustic environments. The Action Proponents train with
various active sonar signals, including up-sweeps and down-sweeps, to
accurately replicate operational scenarios. Reducing training realism
by restricting the signal used would ultimately prevent units from
deploying with the required level of readiness necessary to accomplish
their missions and impede the Action Proponents' ability to certify
forces to deploy to meet national security tasking. Likewise, testing
program requirements include test parameters designed to accurately
determine whether a system is meeting its operational and performance
requirements. Reducing realism by restricting the signal used would
impact the ability of researchers, program managers, and weapons system
acquisition programs to effectively test systems and platforms (and
components of these systems and platforms) before full-scale production
or delivery to the fleet. For these reasons, the Navy has determined,
and NMFS concurs, that modifying or limiting the sonar signal as
mitigation is impractical to implement as it would result in degraded
realism of training and testing.
NMFS and the Navy will explore whether future studies on the
efficacy and practicality of signal modification are appropriate in
consideration of other ongoing research efforts, including some
recommended by the commenter (e.g., thermal detection). However, at
this time, given the numerous other research priorities and established
impracticality, NMFS is not requiring the Action Proponents to
investigate the efficacy of signal modification.
Comment 28: The Commission recommended that NMFS require Action
Proponents' surface ships to maintain a speed of no more than 10 kn
(18.5 km/hr) during transits when a NARW is observed, if the vessels
are within 5 nmi (9.3 km) of a reported sighting, at night, and during
periods of reduced visibility in the Northeast North Atlantic Right
Whale Mitigation Area year-round and the Southeast North Atlantic Right
Whale Mitigation Area from November 15 to April 15. The Commission also
recommended that NMFS require Action Proponents' surface ships to
maintain a speed of no more than 10 kn (18.5 km/hr) during transits
when a Rice's whale is observed, at night, and during periods of
reduced visibility in the Rice's Whale Mitigation Area year-round.
In a related comment, a commenter stated that according to the
current vessel speed rule that was put into place to protect NARWs,
military vessels are exempt from the speed restrictions. The commenter
states that increasing naval vessel traffic in these same regions,
especially when military vessels are exempt from civilian speed
restrictions, will only heighten the risk of fatal interactions.
Response: The proposed rule included multiple requirements to
minimize the risk of vessel strike to NARW and Rice's whales, including
a requirement within the Northeast North Atlantic Right Whale
Mitigation Area requiring surface ships to implement speed reductions
after observing a NARW, if transiting within 5 nmi (9.3 km) of a
sighting reported to the North Atlantic Right Whale Sighting Advisory
System within the past week, and when transiting at night or during
periods of reduced visibility. It also included a requirement in the
Southeast North Atlantic Right Whale Mitigation Area that from November
15 to April 15 requiring surface ships to minimize north-south transits
to the maximum extent practical, and implement speed reductions after
they observe a NARW, if they are within 5 nmi (9.3 km) of an Early
Warning System sighting reported within the past 12 hours, and at night
and in poor visibility. This final rule includes several additional
measures to reduce the risk of vessel strike, as described below.
Within the Southeast North Atlantic Right Whale Mitigation Area,
from November 15 to April 15, the Action Proponents must not conduct
vessel propulsion testing. Further, this final rule includes a new
Martha's Vineyard North Atlantic Right Whale Mitigation Area in which
the Action Proponents must avoid conducting vessel propulsion testing
events to the maximum extent practical. Additionally, in the Dynamic
North Atlantic Right Whale Mitigation Area, the extent of which matches
the boundary of the U.S. EEZ on the East Coast, the Action Proponents
must provide North Atlantic Right Whale Dynamic Management Area
information (e.g., location and dates) to applicable assets transiting
and training or testing in the vicinity of the Dynamic Management Area.
The information must alert assets (and their Lookouts) to the possible
presence of NARW in their vicinity. Lookouts must use the information
to help inform visual observations during military readiness activities
that involve vessel movements, active sonar, in-water explosives
(including underwater explosives and explosives deployed against
surface targets), or non-explosive ordnance deployed against surface
targets in the mitigation area.
In PMAP reports generated in the Dynamic North Atlantic Right Whale
Mitigation Area, this final rule requires that Action Proponents must
provide the WhaleMap web address (<a href="https://whalemap.org">https://whalemap.org</a>) and advise that
risk of whale strike is increased after: (1) observing a NARW; (2) when
operating within 5 nmi (6.5 km) of a known sighting reported within the
past 24 hours; (3) within a NMFS-designated Seasonal Management Area,
Dynamic Management Area, or Slow Zone; and (4) when transiting at night
or during periods of reduced visibility. The PMAP report must also
reinforce the requirement of the COLREGS for vessels to proceed at a
safe speed, appropriate for the prevailing circumstances and
conditions, to avoid a collision with any sighted object or
disturbance, including any marine mammal. Additionally, this final rule
requires that during propulsion testing in the Dynamic North Atlantic
Right Whale Mitigation Area, to the maximum extent practical, Lookouts
must be provided recent <a href="https://whalemap.org">https://whalemap.org</a> sightings data to help
inform visual observations.
This final rule also requires that within the first year of AFTT
Phase IV implementation, the Action Proponents must work
collaboratively with the NMFS ESA Interagency Cooperation Division and
the NMFS Permits and Conservation Division to: (1) analyze and discuss
the application of new information from the NMFS North Atlantic Right
Whale Persistence Modelling Efforts toward AFTT mitigation measures;
(2) evaluate the practicability and conservation benefits of newly
proposed mitigation measures and/or changes to existing measures based
on information from the model; and (3) implement any new mitigation
measures or changes to existing measures that meet the Action
Proponents' Practicability Criteria and Sufficiently Beneficial
requirements.
This final rule also includes two new measures to reduce the risk
of vessel strike of Rice's whale. The Action Proponents must avoid
conducting vessel propulsion testing events in the Rice's Whale
Mitigation Area, to the maximum extent practical. The Action
[[Page 50521]]
Proponents must also issue an annual awareness message to Navy and
Coast Guard vessels that routinely train or test in the vicinity of the
proposed Rice's whale proposed critical habitat. The message will
advise that risk of whale strike is increased when transiting through
proposed Rice's whale proposed critical habitat (i.e., within the 100-
400 m isobaths), particularly at night or during periods of reduced
visibility, and reinforce the requirement of the COLREGS for vessels to
proceed at a safe speed, appropriate for the prevailing circumstances
and conditions, to avoid a collision with any sighted object or
disturbance, including any marine mammal.
The Action Proponents require flexibility in use of variable ship
speeds for training, testing, operational, safety, and engineering
qualification requirements. Action Proponent vessels typically use the
lowest speed practical given individual mission needs. NMFS has
reviewed the analysis of these additional suggested restrictions and
the impacts they would have on military readiness and concurs with the
Navy's assessment that they are impracticable (see section 5.3.4.1
Vessel Movement and section 5.5 Measures Considered but Eliminated in
the 2020 NWTT FSEIS/OEIS). Therefore, the Action Proponents are already
planning to engage in the lowest practicable speed in biologically
important habitats, including in designated critical habitat for NARW
and proposed critical habitat for Rice's whales and other biologically
important habitat for vulnerable species, as well as in all mitigation
areas and other areas. As such, additional restrictions on vessel speed
are not practicable and therefore, are not required.
The commenter did not provide a citation for the statement that
naval vessel traffic is increasing in the AFTT Study Area. The Navy
states that there has not been an increase in vessel traffic related to
AFTT activities since the 2018 analysis. Rather, there has been a
decrease in most areas and a decrease in the AFTT Study Area as a whole
(see table 3.0-9 of the 2025 AFTT Supplemental EIS/OEIS).
Comment 29: A commenter asserted that mitigation measures based on
visual observation (i.e., by Lookouts), such as safety zone
maintenance, results in highly limited risk reduction for most species
and under most conditions. The commenter stated that NMFS should
require infrared and thermal detection technologies as alternative
detection measures for mitigation and monitoring, stating that these
technologies have achieved a readiness level that is capable of
supporting monitoring and mitigation during Phase IV military readiness
activities.
Response: Lookouts remain an important component of the Action
Proponents' mitigation strategy, especially as it relates to minimizing
exposure to the more harmful impacts that may occur within closer
proximity to the source, where Lookouts are most effective. As stated
by the commenter, thermal detection technologies have advanced in
recent years. However, significant limitations still exist, and the
technology has not yet reached the level of performance needed for
deployment during military readiness activities for mitigation uses.
Current technologies are limited by: (1) low sensor resolution and a
narrow field of view; (2) reduced performance in certain environmental
conditions; and (3) high cost and uncertain long-term reliability.
Thermal detection systems are more useful for detecting marine
mammals in some marine environments than others. Current technologies
have limitations regarding water temperature and survey conditions
(e.g., rain, fog, sea state, glare, ambient brightness), for which
further effectiveness studies are required. Thermal detection systems
are generally thought to be most effective in cold environments, which
have a large temperature differential between an animal's temperature
and the environment. Current thermal detection systems have proven more
effective at detecting large whale blows than the bodies of small
animals, particularly at a distance. The effectiveness of current
technologies has not been demonstrated for small marine mammals at-sea
(noting that Richter et al. (2023) demonstrated efficacy in detecting
killer whales in the Salish Sea using land-based thermal imaging
systems). Thermal detection systems exhibit varying degrees of false
positive detections (i.e., incorrect notifications) due in part to
their low sensor resolution and reduced performance in certain
environmental conditions. False positive detections may incorrectly
identify other features (e.g., birds, waves, boats) as marine mammals
(Boebel and Zitterbart, 2017; Zitterbart et al., 2020).
Thermal detection systems for military applications are deployed on
various Department of Defense (DoD) platforms. These systems were
initially developed for nighttime targeting and object detection such
as a boat, vehicle, or people and are not optimized for marine mammal
detections versus object detection, nor do these systems have the
automated marine mammal detection algorithms the Navy is testing via
its ongoing research program. The Action Proponents do not have
available personnel to add Lookouts to use thermal detection systems in
tandem with existing Lookouts who are using traditional observation
techniques.
Existing specialized DoD infrared/thermal capabilities on Navy
aircraft and surface ships are designed for fine-scale targeting.
Viewing arcs of these thermal systems are narrow and focused on a
target area. Furthermore, sensors are typically used only in select
training events and have a limited lifespan before requiring expensive
replacement. Some sensor elements can cost upward of $300,000 to
$500,000 per device, so their use is predicated on a distinct military
need.
The Office of Naval Research sponsored a project from 2019 to 2023
titled ``Development of the Next Generation Automatic Surface Whale
Detection System for Marine Mammal Mitigation and Distribution
Estimation.'' The aim of the project was to develop a system to be used
by non-experts, with minimal installation requirements, applying
algorithms to reliably detect, localize, and identify surfaced marine
mammals from a vessel, while minimizing false detections. In 2024, the
project transitioned to the Navy's Living Marine Resources Program, the
applied research, development, test, and evaluation program that funds
Navy driven research needs to support at-sea compliance and permitting.
Thermal Imaging for Vessel Strike Mitigation on Autonomous Vessels
(Project #LMR-68) will focus on adapting and testing two existing and
proven thermal imaging-based whale detection systems to reduce the
potential for vessel strike during navigation of unmanned Navy surface
vessels.
When infrared and thermal mitigation technologies mature to the
state where they are determined to be sufficiently effective at
mitigating marine mammal impacts when considering the range of
environmental conditions analogous to where the Action Proponents train
and test and the species that could co-occur in space and time with the
activities, then the Action Proponents will assess their compatibility
with military readiness applications on both manned and unmanned
vessels. This would include a practicality assessment of the budget and
acquisition process (including costs associated with designing,
building, installing, maintaining, and manning equipment), the
logistical and physical considerations for retrofitting platforms with
the appropriate equipment and their associated maintenance, repairs, or
replacements (e.g., conducting
[[Page 50522]]
engineering studies to ensure compatibility with existing shipboard
systems), the resource considerations for training personnel to
effectively operate the equipment, and the potential security and
classification issues. New system integration on Action Proponents'
assets can entail up to 5-10 years of effort to account for
acquisition, engineering studies, and development and execution of
systems training.
Given the assessment above, this final rule does not require the
Action Proponents to utilize thermal detection for mitigating training
and testing impacts on marine mammals. As thermal detection technology
improves and practicability of applying the technology for training and
testing activities is further assessed, NMFS will consider whether
requirements to utilize thermal detection for mitigating impacts to
marine mammals is appropriate.
Negligible Impact Determination
Comment 30: A commenter stated that NMFS has not met the negligible
impact standard based on current scientific understanding and
population status of species like the Rice's whale and NARW. The
commenter states that authorizing incidental takes in areas that are
biologically sensitive, federally protected, and home to critically
endangered species sets a dangerous precedent.
In a related comment, a commenter identified six points that they
described as methodological problems that require addressing to ensure
the negligible impact determinations are valid under the MMPA and
Administrative Procedure Act (APA). The six points were: (1) improper
reliance on means and medians in establishing thresholds for auditory
impacts; (2) application of an unrealistic non-conservative auditory
weighting scheme for low-frequency cetaceans; (3) lack of incorporation
of recent behavioral response data into biphasic risk functions; (4)
reduction of modeled take estimates through the application of cut-off
distances; (5) discounting gas-bubble pathology as a mechanism of harm
to marine mammals; and (6) failure to present a meaningful analysis of
the aggregate effects on marine mammal populations.
Response: NMFS disagrees with the commenter's assertion that the
negligible impact standard has not been satisfied for each species or
stock. The commenter has not provided sufficient information to support
their assertion.
As described in the proposed rule and this final rule, serious
injury or mortality of NARW and Rice's whale is neither anticipated nor
authorized, nor is any non-auditory injury. The maximum allowable take
is limited to Level A and B harassment in the form of AUD INJ (table
16). As described in the Auditory Injury from Sonar Acoustic Sources
and Explosives and Non-Auditory Injury from Explosives section of the
proposed rule, any take that occurs in the form of TTS is expected to
be lower-level, of short duration (from minutes to, at most, several
hours or less than a day), and mostly not in a frequency band that
would be expected to interfere with NARW or Rice's whale communication
or other important low-frequency cues. Any associated lost
opportunities or capabilities individuals might experience as a result
of TTS would not be at a level or duration that would be expected to
impact reproductive success or survival.
NMFS carefully considered the population status and best scientific
evidence available for Rice's whale, NARW, and all other marine mammal
species and stocks in making its negligible impact determinations. NMFS
has worked with the Navy over the years to increase the spatio-temporal
specificity of the descriptions of activities planned in or near areas
of biological importance, when possible (i.e., in NARW ESA-designated
critical habitat). NMFS' analysis includes explicit consideration of
takes occurring in important areas, as included in appendix A of the
application, and inclusion of mitigation measures in areas of
biological importance, where appropriate. NMFS may still find that the
impacts of a specified activity are negligible even where take occurs
in BIAs, critical habitat, or other important areas, and even though
impacts in these protected areas warrant additional consideration,
including potential mitigation.
As described in the Analysis and Negligible Impact Determination
section and the Mitigation Measures section of the proposed rule and
this final rule, mitigation measures, several of which are designed
specifically to reduce impacts to NARW and Rice's whale, are expected
to further reduce the potential severity of impacts through real-time
operational measures that minimize higher level/longer duration
exposures and time/area measures that reduce impacts in high value
habitat. Specifically, this rule includes several geographic mitigation
areas for NARW: Northeast North Atlantic Right Whale Mitigation Area,
Gulf of Maine Mitigation Area, Martha's Vineyard North Atlantic Right
Whale Mitigation Area, Jacksonville Operating Area North Atlantic Right
Whale Mitigation Area, Southeast North Atlantic Right Whale Mitigation
Area, Dynamic North Atlantic Right Whale Mitigation Area, Major
Training Exercise Planning Awareness Mitigation Areas in the northeast
and mid-Atlantic, and ship shock trial mitigation areas. The Northeast
North Atlantic Right Whale Mitigation Area and Southeast North Atlantic
Right Whale Mitigation Area in particular would reduce exposures in
times and areas where impacts would be more likely to affect feeding
and energetics, or important cow/calf interactions that could lead to
reduced reproductive success or survival, including those in areas
known to be biologically important, and such impacts are not
anticipated. For example, any impacts predicted in the NARW migratory
corridor BIA along the East Coast are less likely to impact individuals
during feeding or breeding behaviors.
For Rice's whale, this rulemaking includes a Rice's Whale
Mitigation Area that overlaps the Rice's whale small and resident
population area identified by NMFS in its 2016 status review (Rosel et
al., 2016) and most of the eastern portion of proposed critical habitat
(88 FR 47453, July 24, 2023). Within this area, the Action Proponents
must not use more than 200 hours of surface ship hull-mounted MFAS
annually and must not detonate in-water explosives (including
underwater explosives and explosives deployed against surface targets)
except during mine warfare activities. Additionally, the Ship Shock
Trial Mitigation Area would ensure the northern Gulf of America ship
shock trial box is situated outside of the Rice's whale core
distribution area identified in 2019 (84 FR 15446). These restrictions
would reduce the severity of impacts to Rice's whales by reducing their
exposure to levels of sound from sonar or explosives that would have
the potential to cause injury or mortality, thereby reducing the
likelihood of those effects and, further, minimizing the severity of
behavioral disturbance.
Responses to the six ``methodological problems'' are included in
NMFS response to Comments 5, 8-11, and 13.
Comment 31: The Commission recommended that NMFS use the two-tiered
approach from NMFS' 2020 Criteria for Determining Negligible Impact
under MMPA Section 101(a)(5)(E) (NMFS, 2020), including using single
negligible impact threshold (NIT<INF>s</INF>) instead of 10 percent of
potential biological removal (PBR), for informing its negligible impact
determinations that involve M/SI for the final rule and other
incidental take authorizations involving M/SI. The Commission asserts
that this
[[Page 50523]]
would provide consistency within NMFS' own policy directive.
Response: As stated in the proposed rule (90 FR 19858, May 9,
2025), on June 17, 2020, NMFS finalized new Criteria for Determining
Negligible Impact under MMPA section 101(a)(5)(E). The guidance
explicitly notes the differences in the negligible impact
determinations required under section 101(a)(5)(E), as compared to
sections 101(a)(5)(A) and 101(a)(5)(D). As stated in the guidance,
first, they differ in terms of the types of take being considered and
consequently, the effects of the takes on population dynamics. In
paragraphs (a)(5)(A) and (D) of section 101, NMFS must determine if the
taking by harassment, injury, or mortality (or a combination of these)
incidental to specified activities will have a negligible impact. In
section 101(a)(5)(E), NMFS must determine if M/SI incidental to
commercial fisheries will have a negligible impact. NMFS considers
mortalities and serious injuries to be removals from the population
that can be evaluated using well-documented models of population
dynamics, whereas harassment and non-serious injury (sub-lethal taking)
are not considered to be removals from the population. Second, they
differ in whether they apply to all marine mammal stocks or only those
stocks or species listed under the ESA: paragraphs (a)(5)(A) and (D) of
section 101 apply to all marine mammal stocks (regardless of ESA
listing status or MMPA depleted status), while paragraph (a)(5)(E)
applies only to stocks designated as depleted because of their listing
under the ESA. The guidance further specifies that the procedure in
that document is limited to how the agency conducts negligible impact
analyses for commercial fisheries under section 101(a)(5)(E) (i.e., it
is not intended to be a broad policy directive for M/SI analyses for
all activities). As described in the Serious Injury and Mortality
section of this final rule, when considering PBR during evaluation of
effects of M/SI under section 101(a)(5)(A), we utilize a two-tiered
analysis for each stock for which M/SI is proposed for authorization:
Tier 1: Compare the total human-caused average annual M/SI estimate
from all sources, including the M/SI proposed for authorization from
the specific activity, to PBR. If the total M/SI estimate is less than
or equal to PBR, then the specific activity is considered to have a
negligible impact on that stock. If the total M/SI estimate (including
from the specific activity) exceeds PBR, conduct the Tier 2 analysis.
Tier 2: Evaluate the estimated M/SI from the specified activity
relative to the stock's PBR. If the M/SI from the specified activity is
less than or equal to 10 percent of PBR and other major sources of
human-caused mortality have mitigation in place, then the individual
specified activity is considered to have a negligible impact on that
stock. If the estimate exceeds 10 percent of PBR, then, absent other
mitigating factors, the specified activity could be considered likely
to have a non-negligible impact on that stock.
In this final rule, NMFS has described its method for considering
PBR to evaluate the effects of potential mortality in the negligible
impact analysis. NMFS has reviewed the 2020 guidance and determined
that our consideration of PBR in the evaluation of mortality, as
described in the Serious Injury and Mortality section of the proposed
rule and in this final rule, remains appropriate for use in the
negligible impact analysis for the Action Proponents' activities under
section 101(a)(5)(A). As such, NMFS disagrees with Commission's
recommendation to use NMFS (2020) to inform its negligible impact
determinations that involve M/SI.
Other Comments
Comment 32: A commenter stated that the manuscripts for the East
Coast and Gulf of America region BIAs have not yet been published;
however, to the best of the commenter's knowledge, the scientific
analysis has been completed and is available to NMFS for decision-
making purposes. This scientific analysis represents the best available
scientific information and should be incorporated into NMFS' impact
analysis.
Response: NMFS and the Action Proponents considered the best
available science in developing the proposed rule and this final rule,
including as it relates to BIAs for marine mammals. While the
manuscripts for updated East Coast and Gulf of America region BIAs have
not yet been published, NMFS and the Navy coordinated with the authors
in development of the proposed rule to understand likely updates to the
BIAs and consider the updated science they would rely upon.
Changes From the Proposed Rule to the Final Rule
Between publication of the proposed rule and development of the
final rule, additional mitigation measures have been added in response
to public comments and further proposals by the Action Proponents.
New mitigation measures were added in the following mitigation
areas: (1) Southeast North Atlantic Right Whale Mitigation Area, (2)
Dynamic North Atlantic Right Whale Mitigation Area, (3) Rice's Whale
Mitigation Area, and (4) Major Training Exercise Planning Awareness
Mitigation Areas.
In the Southeast North Atlantic Right Whale Mitigation Area, this
final rule includes two new requirements. First, from November 15 to
April 15, the Action Proponents must not detonate explosive sonobuoys
within 3 nmi (5.6 km) of the Southeast North Atlantic Right Whale
Mitigation Area. Second, during the same time period, the Action
Proponents must not conduct vessel propulsion testing.
In PMAP reports generated in the Dynamic North Atlantic Right Whale
Mitigation Area, this final rule requires that Action Proponents must
provide the WhaleMap web address (<a href="https://whalemap.org">https://whalemap.org</a>) and advise that
risk of whale strike is increased after: (1) observing a NARW; (2) when
operating within 5 nmi (6.5 km) of a known sighting reported within the
past 24 hours; (3) within a NMFS-designated Seasonal Management Area,
Dynamic Management Area, or Slow Zone; and (4) when transiting at night
or during periods of restricted visibility. The PMAP report must also
reinforce the requirement of the COLREGS for vessels to proceed at a
safe speed, appropriate for the prevailing circumstances and
conditions, to avoid a collision with any sighted object or
disturbance, including any marine mammal. Further, this final rule
requires that sightings data must be used when planning propulsion
testing event details (e.g., timing, location, duration) to minimize
impacts to NARW to the maximum extent practical. During propulsion
testing in the Dynamic North Atlantic Right Whale Mitigation Area, to
the maximum extent practical, Lookouts must be provided recent <a href="https://whalemap.org">https://whalemap.org</a> sightings data to help inform visual observations. Last,
this final rule clarifies that the extent of the mitigation area
matches the boundary of the U.S. EEZ on the East Coast (i.e., the full
extent of where NMFS could potentially establish Dynamic Management
Areas).
In the Rice's Whale Mitigation Area, this final rule includes a
requirement that the Action Proponents must not detonate explosive
sonobuoys within 3 nmi (5.6 km) of the Rice's Whale Mitigation Area as
well as two new measures to further reduce the risk of vessel strike of
Rice's whale. The Action Proponents must avoid conducting vessel
propulsion testing events in the Rice's Whale Mitigation Area, to the
[[Page 50524]]
maximum extent practical. The Action Proponents must also issue an
annual awareness message to Navy vessels that routinely train or test
in the vicinity of the Rice's Whale proposed critical habitat, and
Coast Guard vessels that routinely train anywhere in the Gulf of
America. The message will advise that risk of whale strike is increased
when transiting through Rice's whale proposed critical habitat (i.e.,
within the 100-400 m (328-1,312 ft) isobaths), particularly at night or
during periods of restricted visibility, and reinforce the requirement
of the COLREGS for vessels to proceed at a safe speed, appropriate for
the prevailing circumstances and conditions, to avoid a collision with
any sighted object or disturbance, including any marine mammal.
In the combined Major Training Exercise Planning Awareness
Mitigation Areas located in the Gulf of America, this final rule
includes a requirement that the Action Proponents must not conduct any
MTEs in the mitigation area.
In the Dynamic North Atlantic Right Whale Mitigation Area,
Northeast North Atlantic Right Whale Mitigation Area, Southeast North
Atlantic Right Whale Mitigation Area, and Rice's Whale Mitigation Area,
the term ``reduced visibility'' and ``poor visibility'' were updated to
``restricted visibility'' to align with the COLREGS used by the Action
Proponents to train and test Lookouts.
In addition to the new measures within the existing mitigation
areas, this final rule includes a new Martha's Vineyard North Atlantic
Right Whale Mitigation Area in which the Action Proponents must avoid
conducting vessel propulsion testing events to the maximum extent
practical.
Regarding activity-based mitigation, this final rule clarifies that
the Navy must implement soft start techniques for impact pile driving.
Of note, Navy continues to consider soft-start procedures as part of
their standard operating procedures, and as such, they are not listed
as a mitigation measure in the 2025 AFTT Supplemental EIS/OEIS.
Additionally, a new measure requires that for all activities involving
explosives, if a marine mammal is visibly injured or killed as a result
of detonation, explosives use in the event must be suspended
immediately. This final rule also includes language that describes
instances when activity-based mitigation for physical disturbance and
strike stressors will not be implemented. These are listed in the
Activity-Based Mitigation for Physical Disturbance and Strike Stressors
section of this final rule.
Further, within the first year of AFTT Phase IV implementation, the
Action Proponents must work collaboratively with the NMFS ESA
Interagency Cooperation Division and the NMFS Permits and Conservation
Division to: (1) analyze and discuss the application of new information
from the NMFS North Atlantic Right Whale Persistence Modelling Efforts
toward AFTT mitigation measures; (2) evaluate the practicability and
conservation benefits of newly proposed mitigation measures and/or
changes to existing measures based on information from the model; and
(3) implement any new mitigation measures or changes to existing
measures that meet the Action Proponents' Practicability Criteria and
Sufficiently Beneficial requirements.
This final rule also includes a requirement for cetacean live-
stranding or near-shore atypical milling events. These requirements
have previously been included in the Notification and Reporting Plan
only. In the event of a cetacean live stranding (or near-shore atypical
milling) event within the AFTT Study Area or within 50 km (27 nmi) of
the boundary of the AFTT Study Area, where the NMFS Stranding Network
is engaged in herding or other interventions to return animals to the
water, NMFS Office of Protected Resources (OPR) will advise the Action
Proponents of the need to implement shutdown procedures for all active
acoustic sources or explosive devices within 50 km of the stranding.
Following this initial shutdown, NMFS will communicate with the Action
Proponents to determine whether circumstances support modification of
the shutdown zone. The Action Proponents may decline to implement all
or part of the shutdown if the holder of the LOA, or his/her designee,
determines that it is necessary for national security. Shutdown
procedures for live stranding or milling cetaceans include the
following:
<bullet> If at any time, the marine mammal(s) die or are
euthanized, or if herding/intervention efforts are stopped, NMFS will
immediately advise that the shutdown around the animals' location is no
longer needed;
<bullet> Otherwise, shutdown procedures will remain in effect until
NMFS determines and advises that all live animals involved have left
the area (either of their own volition or following an intervention);
and
<bullet> If further observations of the marine mammals indicate the
potential for re-stranding, additional coordination will be required to
determine what measures are necessary to minimize that likelihood
(e.g., extending the shutdown or moving operations farther away) and to
implement those measures as appropriate.
Regarding reporting requirements, in addition to those included in
the proposed rule, this final rule requires that in the Annual AFTT
Training and Testing Reports, Navy personnel must confirm that foreign
military use of sonar and explosives, when such militaries are
participating in a U.S. Navy-led exercise or event, combined with the
Action Proponents' use of sonar and explosives, would not cause
exceedance of the analyzed levels within each NAEMO modeled sonar and
explosive bin used for estimating predicted impacts.
NMFS also made several updates to its analysis in this final rule.
Since publication of the proposed rule, the Society for Marine
Mammalogy revised the taxonomy for Atlantic white-sided dolphin
(Lagenorhynchus acutus) by reassigning the species to the genus
Leucopleurus. The scientific name of the species is now Leucopleurus
acutus, which has been updated in table 1. Further, in the Group and
Species-Specific Analyses section, NMFS has updated the reproductive
strategy of Bryde's-like whales (i.e., Bryde's whales, Rice's whales)
to ``income'' rather than capital, the movement ecology of Rice's
whales to ``resident'' rather than nomadic, based on Constantine et al.
(2018) and Izadi et al. (2018), as summarized in Garrison et al.
(2024). Additionally, the Commission identified an error related to
potential impacts to goose-beaked whales (Western North Atlantic stock)
in the Preliminary Assessment and Negligible Impact Determination
section of the proposed rule. This final rule includes a correction to
that language to indicate that the impacts to the Western North
Atlantic stock of goose-beaked whales could cause a limited number of
females to forego reproduction for a year.
Description of Marine Mammals and Their Habitat in the Area of
Specified Activities
Marine mammal species and their associated stocks that have the
potential to occur in the AFTT Study Area are presented in table 1
along with each stock's ESA and MMPA statuses, abundance estimate and
associated coefficient of variation (CV) value, minimum abundance
estimate (N<INF>min</INF>), PBR, annual M/SI, and potential occurrence
in the AFTT Study Area. The Action Proponents anticipate take of
individuals of 41 marine mammal species (81 stocks) by Level A and
Level B harassment incidental to military readiness activities from the
use of
[[Page 50525]]
sonar and other transducers, in-water explosives, air guns, pile
driving/extraction, and vessel movement in the AFTT Study Area. The
AFTT proposed rule included additional information about the species in
this rule, marine mammal species for which take is not authorized,
marine mammal species which could occur in the area but are not managed
by NMFS, marine mammal hearing, National Marine Sanctuaries, and the
2010 Deepwater Horizon (DWH) oil spill, all of which remains valid and
applicable but has not been reprinted in this final rule. NMFS hereby
refers to the information and analysis provided in the proposed rule
(90 FR 19858, May 9, 2025) which continue to apply to this final rule.
Information on the status, distribution, abundance, population
trends, habitat, and ecology of marine mammals in the AFTT Study Area
may be found in section 4 of the application. NMFS reviewed this
information and found it to be accurate and complete. Additional
information on the general biology and ecology of marine mammals is
included in the 2025 AFTT Supplemental EIS/OEIS. Table 1 incorporates
the best available science, including data from the U.S. Atlantic and
Gulf of Mexico Marine Mammal Stock Assessment Report (SAR; Hayes et
al., 2024) (now referred to as the Gulf of America; see <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>), and 2024 draft SAR, as well as monitoring data from
the Navy's marine mammal research efforts. NMFS has also reviewed
scientific literature published since publication of the proposed rule
and determined that none of this new information nor any other new
information available changes our determination of which species have
the potential to be affected by the Action Proponents' activities or
the information pertinent to status, distribution, abundance,
population trends, habitat, or ecology of the species in this final
rulemaking, except as noted below.
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Below, we consider additional information about the marine mammals
in the area of the specified activities that informs our analysis, such
as identifying known areas of important habitat or behaviors, or where
unusual mortality events (UME) have been designated.
Critical Habitat
Currently, only the NARW has ESA-designated critical habitat in the
AFTT Study Area. However, NMFS recently published a proposed rule
proposing new ESA-designated critical habitat for the Rice's whale (88
FR 47453, July 24, 2023).
North Atlantic Right Whale
On February 26, 2016, NMFS issued a final rule (81 FR 4838) to
replace the critical habitat for NARW with two new critical habitat
areas. The areas now designated as critical habitat contain
approximately 29,763 nmi\2\ (102,084 km\2\) of marine habitat in the
Gulf of Maine and Georges Bank region (Unit 1), essential for NARW
foraging and off the Southeast U.S. coast (Unit 2), including the coast
of North Carolina, South Carolina, Georgia, and Florida, which are key
areas essential for calving. These two ESA-designated critical habitats
were established to replace three smaller previously ESA-designated
critical habitats (Cape Cod Bay/Massachusetts Bay/Stellwagen Bank,
Great South Channel, and the coastal waters of Georgia and Florida in
the southeastern United States) that had been designated by NMFS in
1994 (59 FR 28805, June 3, 1994). Two additional areas in Canadian
waters, Grand Manan Basin and Roseway Basin, were identified and
designated as critical habitat under Canada's endangered species law
(section 58 (5) of the Species at Risk Act (SARA), S. C. 2002, c. 29)
and identified in Final Recovery Strategy for the NARW, posted June
2009 on the SARA Public Registry.
Unit 1 encompasses the Gulf of Maine and Georges Bank region
including the large embayments of Cape Cod Bay and Massachusetts Bay
and deep underwater basins, as well as state waters, except for inshore
areas, bays, harbors, and inlets, from Maine through Massachusetts in
addition to Federal waters, all of which are key areas (see figure 4.1-
1 of the application). It also does not include waters landward of the
72 COLREGS lines (33 CFR part 80). The essential physical and
biological features of foraging habitat for NARW are: (1) the physical
oceanographic conditions and structures of the Gulf of Maine and
Georges Bank region that combine to distribute and aggregate Calanus
finmarchicus for right whale foraging, namely prevailing currents and
circulation patterns, bathymetric features (basins, banks, and
channels), oceanic fronts, density gradients, and temperature regimes;
(2) low flow velocities in Jordan, Wilkinson, and Georges Basins that
allow diapausing C. finmarchicus to aggregate passively below the
convective layer so that the copepods are retained in the basins; (3)
late stage C. finmarchicus in dense aggregations in the Gulf of Maine
and Georges Bank region; and (4) diapausing C. finmarchicus in
aggregations in the Gulf of Maine and Georges Bank region.
Unit 2 consists of all marine waters from Cape Fear, North
Carolina, southward to approximately 27 nmi (50 km) below Cape
Canaveral, Florida, within the area bounded on the west by the
shoreline and the 72 COLREGS lines, and on the east by rhumb lines
connecting the specific points described below (see figure 4.1-2 of the
application). The essential physical and biological features correlated
with the distribution of NARW in the southern critical habitat area
provide an optimum environment for calving. These essential physical
and biological features are: (1) calm sea surface conditions of Force 4
or less on the Beaufort Wind Scale; (2) sea surface temperatures from a
minimum of 44.6 degrees Fahrenheit ([deg]F) (7 [deg]Celsius (C)), and
never more than 62.6 [deg]F (17 [deg]C); and (3) water depths of 19.7
to 91.9 ft (6 to 28 m), where these features simultaneously co-occur
over contiguous areas of at least 231 nmi\2\ (792.3 km\2\) of ocean
waters during the months of November through April. For example, the
bathymetry of the inner and nearshore middle shelf area minimizes the
effect of strong winds and offshore waves, limiting the formation of
large waves and rough water. The average temperature of critical
habitat waters is cooler during the time right whales are present due
to a lack of influence by the Gulf Stream and cool freshwater runoff
from coastal areas. The water temperatures may provide an optimal
balance between offshore waters that are too warm for nursing mothers
to tolerate, yet not too cool for calves that may have only minimal
fatty insulation. Reproductive females and calves are expected to be
concentrated in the critical habitat from December through April.
Rice's Whale
On August 23, 2021, NMFS published a final rule that revised the
listing of Rice's whales under the ESA to reflect the change in the
scientifically accepted taxonomy and nomenclature of this species (86
FR 47022). Prior to this revision, the Rice's whale was listed in 2019
under the ESA as an endangered subspecies of the Bryde's whale (Gulf of
America subspecies (referred to as the Gulf of Mexico subspecies in 86
FR 47022)). The 2019 listing rule indicated that, with a total
abundance of approximately 100 individuals, small population size and
restricted range are the most serious threats to this species (84 FR
15446, April 15, 2019). However, other threats such as energy
exploration, development, and production; oil spills and oil spill
responses; vessel collision; fishing gear entanglement; and
anthropogenic noise were also identified as threats that contribute to
the risk of extinction.
The specific occupied areas proposed for designation as critical
habitat for the Rice's whale contain approximately 28,270.65 mi\2\
(73,220.65 km\2\) of continental shelf and slope associated waters
between the 100-400 m (328-1,312 ft) isobaths within the Gulf of
America spanning from the U.S. EEZ boundary off the southwestern coast
of Texas, to the boundary between the South Atlantic Fishery Management
Council and the Gulf Fishery Management Council off the southeastern
coast of Florida.
In the final listing rule, NMFS stated that critical habitat was
not determinable at the time of the listing, because sufficient
information was not currently available on the geographical area
occupied by the species (84 FR 15446, April 15, 2019). On July 24,
2023, NMFS published a proposed rule describing the proposed critical
habitat designation, including supporting information on Rice's whale
biology, distribution, and habitat use, and the methods used to develop
the proposed designation (88 FR 47453). The physical and biological
features essential to the conservation of the species identified in the
proposed rule are: (1) sufficient density, quality, abundance, and
accessibility of small demersal and vertically migrating prey species,
including scombriformes, stomiiformes, myctophiformes, and myopsida;
(2) marine water with (i) elevated productivity, (ii) bottom
temperatures of 50-66.2 [deg]F (10-19 [deg]C), and (iii) levels of
pollutants that do not preclude or inhibit any demographic function;
and (3) sufficiently quiet conditions for normal use and occupancy,
including intraspecific communication, navigation, and detection of
prey, predators, and other threats.
Biologically Important Areas
LaBrecque et al. (2015) identified BIAs within U.S. waters of the
East Coast and Gulf of America (referred to as the Gulf of Mexico in
the LaBrecque
[[Page 50545]]
et al. (2015)), which represent areas and times in which cetaceans are
known to concentrate in areas of known importance for activities
related to reproduction, feeding, and migration, or areas where small
and resident populations are known to occur. Unlike ESA critical
habitat, these areas are not formally designated pursuant to any
statute or law but are a compilation of the best available science
intended to inform impact and mitigation analyses. An interactive map
of the BIAs is available here: <a href="https://oceannoise.noaa.gov/biologically-important-areas">https://oceannoise.noaa.gov/biologically-important-areas</a>. In some cases, additional, or newer,
information regarding known feeding, breeding, or migratory areas may
be available, and is included below.
On the East Coast, 19 of the 24 identified BIAs fall within or
overlap with the AFTT Study Area: 10 feeding (2 for minke whale, 1 for
sei whale, 3 for fin whale, 3 for NARW, and 1 for humpback), 1
migration (NARW), 2 reproduction (NARW), and 6 small and resident
population (1 for harbor porpoise and 5 for bottlenose dolphin).
Figures 4.1-1 through 4.1-14 of the application illustrate how these
BIAs overlap with OPAREAs on the East Coast. In the Gulf of America, 4
of the 12 identified BIAs for small and resident populations overlap
the AFTT Study Area (1 for Rice's (Bryde's) whale and 3 for bottlenose
dolphin). Figures 4.1-9 through 4.1-13 of the application illustrates
how these BIAs overlap with OPAREAs in the Gulf of America.
Large Whales Feeding BIAs--East Coast
Two minke whale feeding BIAs are located in the northeast Atlantic
from March through November in waters less than 200 m (656 ft) in the
southern and southwestern section of the Gulf of Maine including
Georges Bank, the Great South Channel, Cape Cod Bay and Massachusetts
Bay, Stellwagen Bank, Cape Anne, and Jeffreys Ledge (LaBrecque et al.,
2015a; LaBrecque et al., 2015b). LaBrecque et al. (2015b) delineated a
feeding area for sei whales in the northeast Atlantic between the 25-m
(82-ft) contour off coastal Maine and Massachusetts to the 200-m (656-
ft) contour in central Gulf of Maine, including the northern shelf
break area of Georges Bank. The feeding area also includes the southern
shelf break area of Georges Bank from 100 m to 2,000 m (328 ft to 6,562
ft) and the Great South Channel. Feeding activity is concentrated from
May through November with a peak in July and August. LaBrecque et al.
(2015b) identified three feeding areas for fin whales in the North
Atlantic within the AFTT Study Area: (1) June to October in the
northern Gulf of Maine; (2) year-round in the southern Gulf of Maine,
and (3) March to October east of Montauk Point. LaBrecque et al.
(2015b) delineated a humpback whale feeding area in the Gulf of Maine,
Stellwagen Bank, and Great South Channel.
North Atlantic Right Whale BIAs--East Coast and Additional Information
LaBrecque et al. (2015b) identified three seasonal NARW feeding
areas BIAs located in or near the AFTT Study Area: (1) February to
April on Cape Cod Bay and Massachusetts Bay; (2) April to June in the
Great South Channel and on the northern edge of Georges Bank; and (3)
June to July and October to December on Jeffreys Ledge in the western
Gulf of Maine. A mating BIA was identified in the central Gulf of Maine
(from November through January), a calving BIA in the southeast
Atlantic (from mid-November to late April) and the migratory corridor
area BIA along the U.S. East Coast between the NARW southern calving
grounds and northern feeding areas (see figures 4.1-1 through 4.1-14 of
the application for how these BIAs overlap with Navy OPAREAs).
In addition to the BIAs described above, an area south of Martha's
Vineyard and Nantucket, primarily along the western side of Nantucket
Shoals, was recently described as an important feeding area (Kraus et
al., 2016; O'Brien et al., 2022, Quintano-Rizzo et al., 2021). Its
importance as a foraging habitat is well established (Leiter et al.,
2017; Estabrook et al., 2022; O'Brien et al., 2022). Nantucket Shoals'
unique oceanographic and bathymetric features, including a persistent
tidal front, help sustain year-round elevated phytoplankton biomass and
aggregate zooplankton prey for NARW (White et al., 2020; Quintana-Rizzo
et al., 2021). O'Brien et al. (2022) hypothesize that NARW southern New
England habitat use has increased in recent years (i.e., over the last
decade) as a result of either, or a combination of, a northward shift
in prey distribution (thus increasing local prey availability) or a
decline in prey in other abandoned feeding areas (e.g., Gulf of Maine).
Pendleton et al. (2022) characterize southern New England as a
``waiting room'' for NARW in the spring, providing sufficient, although
sub-optimal, prey choices while NARW wait for C. finmarchicus supplies
in Cape Cod Bay (and other primary foraging grounds like the Great
South Channel) to optimize as seasonal primary and secondary production
progresses. Throughout the year, southern New England provides
opportunities for NARW to capitalize on C. finmarchicus blooms or
alternative prey (e.g., Pseudocalanus elongatus and Centropages
species, found in greater concentrations than C. finmarchicus in
winter), although likely not to the extent provided seasonally in more
well-understood feeding habitats like Cape Cod Bay in late spring or
the Great South Channel (O'Brien et al., 2022). Although extensive data
gaps, highlighted in a recent report by the National Academy of
Sciences (NAS) (2023), have prevented development of a thorough
understanding of NARW foraging ecology in the Nantucket Shoals region,
it is clear that the habitat was historically valuable to the species
given historic whaling activity there. It has become increasingly
valuable over the last decade.
Harbor Porpoise BIA--East Coast
LaBrecque et al. (2015b) identified a small and resident population
BIA for harbor porpoise in the Gulf of Maine (see figure 4.1-14 of the
application). From July to September, harbor porpoises are concentrated
in waters less than 150 m (492 ft) deep in the northern Gulf of Maine
and southern Bay of Fundy. During fall (October to December) and spring
(April to June), harbor porpoises are widely dispersed from New Jersey
to Maine, with lower densities farther north and south (LaBrecque et
al., 2015b).
Bottlenose Dolphin BIA--East Coast
LaBrecque et al. (2015b) identified nine small and resident
bottlenose dolphin population areas within estuarine areas along the
east coast of the U.S. (see figure 4.1-11 of the application). These
areas include estuarine and nearshore areas extending from Pamlico
Sound, North Carolina down to Florida Bay, Florida (LaBrecque et al.,
2015b). The Northern North Carolina Estuarine System, Southern North
Carolina Estuarine System, and Charleston Estuarine System populations
partially overlap with nearshore portions of the Navy Cherry Point
Range Complex, and Jacksonville Estuarine System Populations partially
overlap with nearshore portions of the Jacksonville Range Complex. The
Southern Georgia Estuarine System Population area also overlaps with
the Jacksonville Range Complex, specifically within Naval Submarine
Base Kings Bay, Kings Bay, Georgia and includes estuarine and
intercoastal waterways from Altamaha Sound to the Cumberland River
(LaBrecque et al., 2015b). The remaining
[[Page 50546]]
four BIAs are outside but adjacent to the AFTT Study Area boundaries.
Bottlenose Dolphin BIA--Gulf of America
LaBrecque et al. (2015) also described 11 year-round BIAs for small
and resident estuarine stocks of bottlenose dolphin that primarily
inhabit inshore waters of bays, sounds, and estuaries (BSE) in the Gulf
of America (see figures 4.1-12 and 4.1-13 in the application). Of the
11 BIAs identified for the BSE bottlenose dolphins in the Gulf of
America, 3 overlap with the Gulf Range Complex (Aransas Pass Area,
Texas; Mississippi Sound Area, Mississippi; and St. Joseph Bay Area,
Florida), while 8 are located adjacent to the AFTT Study Area
boundaries.
Rice's (Previously Bryde's) Whale BIA--Gulf of America
The Rice's (previously Bryde's) whale is a very small population
that is genetically distinct from Bryde's whales and not genetically
diverse within the Gulf of America (Rosel and Wilcox, 2014; Rosel et
al., 2021). Further, the species is typically observed only within a
narrowly circumscribed area within the eastern Gulf of America.
Therefore, this area is described as a year-round BIA by LaBrecque et
al. (2015). Previous survey effort covered all oceanic waters of the
U.S. Gulf of America, and whales were observed only between
approximately the 100- and 300-m (328- and 984-ft) isobaths in the
eastern Gulf of America from the head of the De Soto Canyon (south of
Pensacola, Florida) to northwest of Tampa Bay, Florida (Maze-Foley and
Mullin, 2006; Waring et al., 2016; Rosel and Wilcox, 2014; Rosel et
al., 2016). Rosel et al. (2016) expanded this description by stating
that, due to the depth of some sightings, the area is more
appropriately defined to the 400-m (1,312-ft) isobath and westward to
Mobile Bay, Alabama, in order to provide some buffer around the deeper
sightings and to include all sightings in the northeastern Gulf of
America. Since then, passive acoustic detections of Rice's whale have
occurred in the north central and western Gulf of America (Soldevilla
et al., 2022; Soldevilla et al., 2024), although the highest densities
of Rice's whales have been confined to the northeastern Gulf of America
core habitat. The number of individuals that occur in the central and
western Gulf of America and nature of their use of this area is poorly
understood. Soldevilla et al. (2022) suggest that more than one
individual was present on at least one occasion, as overlapping calls
of different call subtypes were recorded in that instance, but also
state that call detection rates suggest that either multiple
individuals are typically calling or that individual whales are
producing calls at higher rates in the central and western Gulf of
America. Soldevilla et al. (2024) provide further evidence that Rice's
whale habitat encompasses all 100-400 m (328-1,312 ft) depth waters
encircling the entire Gulf of America, including Mexican waters (as
described in the proposed critical habitat designation (88 FR 47453,
July 24, 2023)), but they also note that further research is needed to
understand the density of whales in these areas, seasonal changes in
whale density, and other aspects of habitat usage.
Unusual Mortality Events
A UME is defined under section 410(9) of the MMPA as a stranding
that is unexpected; involves a significant die-off of any marine mammal
population; and demands immediate response. Three UMEs with ongoing
investigations in the AFTT Study Area that inform our analysis are
discussed below. The 2022 Maine Pinniped UME has closed and the 2018
Northeast Pinniped UME is non-active and pending closure.
North Atlantic Right Whale (2017-Present)
Beginning in 2017, elevated mortalities in NARW were documented in
Canada and the United States and necessitated a UME be declared. The
whales impacted by the UME include dead, injured, and sick individuals,
who represent more than 20 percent of the population, which is a
significant impact on an endangered species where deaths are outpacing
births. Additionally, research demonstrates that only about one-third
of right whale deaths are documented. The preliminary cause of
mortality, serious injury, and morbidity (sublethal injury and illness)
in most of these whales is from entanglements or vessel strikes.
Endangered NARW are approaching extinction. There are approximately 372
individuals remaining, including fewer than 70 reproductively active
females. Human impacts continue to threaten the survival of this
species. The many individual whales involved in the UME are a
significant setback to the recovery of this endangered species.
Since 2017, dead, seriously injured, sublethally injured, or ill
NARW along the U.S. and Canadian coasts have been documented,
necessitating a UME declaration and investigation. The leading category
for the cause of death for this ongoing UME is ``human interaction,''
specifically from entanglements or vessel strikes. As of September 4,
2025, there have been 41 confirmed mortalities (dead, stranded, or
floating) and 39 seriously injured free-swimming whales for a total of
80 whales. The UME also considers animals with sublethal injury or
illness (i.e., ``morbidity''; n = 76) bringing the total number of
whales in the UME to 156. More information about the NARW UME is
available online at: <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2025-north-atlantic-right-whale-unusual-mortality-event">https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2025-north-atlantic-right-whale-unusual-mortality-event</a>.
Humpback Whale (2017-Present)
Since January 2016, elevated humpback whale mortalities have
occurred along the Atlantic coast from Maine to Florida. This event was
declared a UME in April 2017. Partial or full necropsy examinations
have been conducted on approximately half of the 257 known cases (as of
September 4, 2025). Of the whales examined (approximately 90), about 40
percent had evidence of human interaction either from vessel strike or
entanglement. While a portion of the whales have shown evidence of pre-
mortem vessel strike, this finding is not consistent across all whales
examined and more research is needed. NOAA is consulting with
researchers that are conducting studies on the humpback whale
populations, and these efforts may provide information on changes in
whale distribution and habitat use that could provide additional
insight into how these vessel interactions occurred. More information
is available at: <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/2016-2025-humpback-whale-unusual-mortality-event-along-atlantic-coast">https://www.fisheries.noaa.gov/national/marine-life-distress/2016-2025-humpback-whale-unusual-mortality-event-along-atlantic-coast</a>.
Minke Whale (2017-Present)
Elevated minke whale mortalities detected along the Atlantic coast
from Maine through South Carolina resulted in the declaration of an on-
going UME in 2017. As of September 4, 2025, a total of 205 minke whales
have stranded during this UME. Full or partial necropsy examinations
were conducted on more than 60 percent of the whales. Preliminary
findings show evidence of human interactions or infectious disease, but
these findings are not consistent across all of the minke whales
examined, so more research is needed. More information is available at:
<a href="https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2025-minke-whale-unusual-mortality-event-along-atlantic-coast">https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2025-minke-whale-unusual-mortality-event-along-atlantic-coast</a>.
[[Page 50547]]
Phocid Seals (2018-2020, 2022)
Harbor and gray seals have experienced two UMEs since 2018,
although one was recently closed (2022 Pinniped UME in Maine) and
closure of the other, described here, is pending. Beginning in July
2018, elevated numbers of harbor seal and gray seal mortalities
occurred across Maine, New Hampshire, and Massachusetts. Additionally,
stranded seals have shown clinical signs as far south as Virginia,
although not in elevated numbers, therefore the UME investigation
encompassed all seal strandings from Maine to Virginia. A total of
3,152 reported strandings (of all species) occurred from July 1, 2018,
through March 13, 2020. Full or partial necropsy examinations were
conducted on some of the seals and samples were collected for testing.
Based on tests conducted thus far, the main pathogen found in the seals
is phocine distemper virus. NMFS is performing additional testing to
identify any other factors that may be involved in this UME, which is
pending closure. Information on this UME is available online at:
<a href="https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along">https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along</a>.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
We provided a detailed discussion of the potential effects of the
specified activities on marine mammals and their habitat in our
proposed rule (90 FR 19858, May 9, 2025). NMFS hereby refers to the
information and analysis provided in the proposed rule which continue
to apply to this final rule. In the Potential Effects of Specified
Activities on Marine Mammals and Their Habitat section of the proposed
rule, NMFS provided a description of the ways marine mammals may be
affected by these activities in the form of, among other things,
serious injury or mortality, physical trauma, sensory impairment
(permanent and TTS and acoustic masking), physiological responses
(particularly stress responses), behavioral disturbance, or habitat
effects. All of this information remains valid and applicable.
Therefore, we do not reprint the information here but refer the reader
to that document.
NMFS has also reviewed new relevant information from the scientific
literature since publication of the proposed rule. Summaries of the new
key scientific literature reviewed since publication of the proposed
rule are presented below.
Cur[eacute] et al. (2025) examined the effects of MFAS received
level and source distance on the behavioral responses of 14 tagged male
sperm whales off northern Norway. Behavioral responses were scored
using the severity scale from Southall et al. (2021), with probability
and severity of behavioral responses (e.g., changes in vocal and dive
behaviors, avoidance, cessation of feeding or resting, locomotion or
orientation changes) increasing with higher received levels (maximum
sound exposure level) and closer source proximities. From observations,
modeling indicates that beyond 14 km (7.6 nmi) no significant
behavioral responses are predicted regardless of received level.
Wensveen et al. (2025), using the same animals from Cur[eacute] et
al. (2025), concluded that source proximity (close: vessels
transmitting MFAS starting at 7.4 km (4 nmi) while approaching focal
whale vs. distant: vessels transmitting MFAS starting 14.8 km (8 nmi)
while approaching focal whale) influenced sperm whale behavioral
responses by resulting in decreased foraging time with increased
received levels and decreased source proximity, as well as short-term
sensitization with subsequent exposure sessions. Specifically, sperm
whales were found to increase time in a non-foraging behavioral state
or produced a decrease in buzzes (indicative of reduced prey capture)
when foraging with MFAS exposure.
Henderson et al. (2025) examined the potential behavioral effects
of Navy Submarine Command Courses (SCC) involving MFAS (i.e., hull-
mounted; sonobuoys; helicopter-dipping) off the Pacific Islands Missile
Range Facility (PMRF) on three satellite-tagged Blainville's beaked
whales (there was a fourth tagged individual but it did not remain on
the range during MFAS exposure). Behavioral responses showed individual
variation but short-term changes in dive behavior and horizontal
movements were detected. However, only temporary horizontal avoidance
was observed, with animals remaining near PMRF (within 10s of
kilometers) throughout the SCC and in two situations returning to PMRF
after the SCC was completed. Received levels were up to 150 dB, with
sources closest points of approach (CPAs) at 18 km (9.7 nmi).
Previous marine mammal TTS studies have followed the trend that
susceptibility to noise-induced hearing loss reflects baseline hearing
thresholds by frequency (i.e., audiogram; where frequencies with lower
baseline thresholds (lowest point in audiogram) being more susceptible
to threshold shifts from noise than frequencies with higher baseline
thresholds (at edges of hearing range)). Kastelein et al. (2025a)
examined this trend using three species (harbor porpoise, California
sea lion, and harbor seal) with similar baseline hearing thresholds
(59-61 dB) at 8 kHz. Despite similar baseline thresholds at 8 kHz, TTS
onset (6 dB threshold shift) varied among the species: 169 dB
cumulative SEL for harbor porpoise, 176 dB cumulative SEL for
California sea lion, and 182 dB cumulative SEL for harbor seal. Thus,
despite similar baseline thresholds at 8 kHz, susceptibility varies
among species and confirms it is not appropriate extrapolated data
between species.
Kastelein et al. (2025b) examined TTS in two harbor seals exposed
to one-sixth octave band noise centered 8 kHz. In this study, TTS onset
(6 dB threshold shift) occurred at approximately 181 dB cumulative SEL,
which is 6 dB higher than what is predicted with the current Navy Phase
IV criteria (i.e., current Navy Phase IV criteria is considered more
protective). Furthermore, the equal energy hypothesis is supported
based on the noise exposure scenarios (e.g., frequency, duration, sound
pressure levels) used in this study.
Having considered the new information, along with information
provided in public comments on the proposed rule, we have determined
that there is no new information that substantively affects our
analysis of potential impacts on marine mammals and their habitat that
appeared in the proposed rule, all of which remains applicable and
valid for our assessment of the effects of the Action Proponents'
activities during the 7-year period of this rule.
Estimated Take of Marine Mammals
This section indicates the number of takes NMFS is authorizing,
which is based on the amount of take NMFS anticipates is reasonably
likely to occur. NMFS coordinated closely with the Action Proponents in
the development of their incidental take application and agrees that
the methods the Action Proponents have 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.
The 2025 AFTT Supplemental EIS/OEIS considered all military
readiness activities planned to occur in the AFTT Study Area that have
the potential to result in the MMPA defined take of marine mammals. The
Action Proponents determined that the three stressors below could
result in the incidental taking of marine mammals.
[[Page 50548]]
NMFS has reviewed the Action Proponents' 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 specified activities:
<bullet> Acoustics (sonars and other transducers, air guns, pile
driving/extraction);
<bullet> Explosives (explosive shock wave and sound, assumed to
encompass the risk due to fragmentation); and
<bullet> Vessel strike.
Acoustic and explosive sources are likely to result in incidental
takes of marine mammals by harassment. Explosive sources and vessel
strikes have the potential to result in incidental take by injury,
serious injury, and/or mortality.
For this military readiness activity, section 3(18)(B) of the MMPA
(16 U.S.C. 1362(18)(B)) defines ``harassment'' as: (1) 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 (2) 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 the behavioral patterns are
abandoned or significantly altered (Level B harassment).
Authorized takes are primarily in the form of Level B harassment,
as use of the acoustic (e.g., active sonar, pile driving, and air guns)
and explosive sources is most likely to result in disruption of natural
behavioral patterns to a point where they are abandoned or
significantly altered (as defined specifically at the beginning of this
section, but referred to generally as behavioral disturbance) for
marine mammals, either via direct behavioral disturbance or TTS. There
is also the potential for Level A harassment, in the form of AUD INJ to
result from exposure to the sound sources utilized in military
readiness activities. Lastly, no more than 6 serious injuries or
mortalities total (over the 7-year period) of large whales could
potentially occur through vessel strikes, and 13 serious injuries or
mortalities (over the 7-year period) from explosive use. Although we
analyze the impacts of these potential serious injuries or mortalities
that are authorized, the required mitigation and monitoring measures
are expected to minimize the likelihood (i.e., further lower the
already low probability) that vessel strike (and the associated serious
injury or mortality) would occur, as well as the severity of other
takes (including serious injury or mortality from use of explosives).
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
would experience behavioral disturbance or incur some degree of
temporary or permanent hearing impairment; (2) the area or volume of
water that would 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.
We provided a detailed discussion of the acoustic thresholds,
acoustic effects modeling and estimation, range to effects for
stressors, and marine mammal density information in our proposed rule
(90 FR 19858, May 9, 2025). NMFS hereby refers to the information and
analysis provided in the proposed rule which continue to apply to this
final rule. In the Estimated Take of Marine Mammals section of the
proposed rule, we identified the subset of potential effects that would
be expected to qualify as take both annually and over the 7-year period
covered by the rule, then identified the maximum number of takes we
believe could occur (mortality) or are reasonably expected to occur
(harassment) based on the methods described. All of this information
remains valid and applicable. Therefore, we do not repeat the
information here, but refer the reader to the proposed rule.
Estimated Take From Acoustic Stressors
The quantitative analysis process used for the 2025 AFTT
Supplemental EIS/OEIS and the application to estimate potential
exposures to marine mammals resulting from acoustic and explosive
stressors is detailed in the Acoustic Impacts Technical Report.
Regarding how avoidance of loud sources is considered in the take
estimation, NAEMO does not simulate horizontal animat movement during
an event. However, NAEMO approximates marine mammal avoidance of high
sound levels due to exposure to sonars in a one-dimensional calculation
that scales how far an animat would be from a sound source based on
sensitivity to disturbance, swim speed, and avoidance duration. This
process reduces the SEL, defined as the accumulation for a given
animat, by reducing the received SPL of individual exposures based on a
spherical spreading calculation f
[…truncated; see source link]Indexed from Federal Register on November 7, 2025.
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