`[Federal Register Volume 90, Number 10 (Thursday, January 16, 2025)]
[Proposed Rules]
[Pages 4944-5029]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-31402]



[[Page 4943]]

Vol. 90

Thursday,

No. 10

January 16, 2025

Part IV





Department of Commerce





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 National Oceanic and Atmospheric Administration





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50 CFR Part 218





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

  Federal Register / Vol. 90, No. 10 / Thursday, January 16, 2025 / 
Proposed Rules  

[[Page 4944]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 218

[Docket No. 241220-0334]
RIN 0648-BL72


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

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Final rule; notification of issuance of Letters of 
Authorization.

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SUMMARY: NMFS, upon request from the U.S. Navy (Navy), issues these 
regulations pursuant to the Marine Mammal Protection Act (MMPA) to 
govern the taking of marine mammals incidental to the training and 
testing activities conducted in the Hawaii-Southern California Training 
and Testing (HSTT) Study Area between 2018 and 2025. In 2021, two 
separate U.S. Navy vessels struck unidentified large whales on two 
separate occasions, one whale in June 2021 and one whale in July 2021, 
in waters off Southern California. The takes by vessel strike of the 
two whales by the U.S. Navy were covered by the existing regulations 
and Letters of Authorization (LOAs), which authorize the U.S. Navy to 
take up to three large whales by serious injury or mortality by vessel 
strike between 2018 and 2025. The Navy reanalyzed the potential of 
vessel strike in the HSTT Study Area, including the recent strikes, and 
as a result, requested two additional takes of large whales by serious 
injury or mortality by vessel strike for the remainder of the current 
regulatory period. In May 2023, a U.S. Navy vessel struck a large whale 
in waters off Southern California. NMFS reanalyzed the potential for 
vessel strike based on new information, including the three strikes, 
and authorizes two additional takes of large whales by serious injury 
or mortality by vessel strike for the remainder of the current 
regulatory period (two takes in addition to the three takes authorized 
in the current regulations). The Navy's activities qualify as military 
readiness activities pursuant to the MMPA, as amended by the National 
Defense Authorization Act for Fiscal Year 2004 (2004 NDAA).

DATES: Effective from January 16, 2025 to December 20, 2025.

ADDRESSES: Copies of the Navy's applications, NMFS' proposed and final 
rules and subsequent LOAs for these regulations, NMFS' proposed and 
final rules and subsequent LOAs for the associated 5-year HSTT Study 
Area regulations, other supporting documents cited herein, and a list 
of the references cited in this document may be obtained online at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. In case 
of problems accessing these documents, please use the contact listed 
here (see FOR FURTHER INFORMATION CONTACT).

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

SUPPLEMENTARY INFORMATION:

Purpose of Regulatory Action

    These regulations, promulgated under the authority of the MMPA (16 
U.S.C. 1361 et seq.), modify previous regulations which allow for the 
authorization of take of marine mammals incidental to the Navy's 
training and testing activities (which qualify as military readiness 
activities) from the use of sonar and other transducers, in-water 
detonations, air guns, impact pile driving/vibratory extraction, and 
the movement of vessels throughout the HSTT Study Area (50 CFR part 
218, subpart H; hereafter ``2020 HSTT regulations'').
    NMFS received a request from the Navy to modify the 2020 HSTT 
regulations and LOAs to authorize two additional takes of large whales 
by serious injury or mortality by vessel strike over the remainder of 
the HSTT regulatory period. The 2020 HSTT regulations and LOAs 
authorized the incidental take, by serious injury or mortality, of 
three large whales by vessel strike. Here, in consideration of the best 
available science, including updated information related to vessel 
strikes, NMFS analyzes and authorizes the incidental serious injury or 
mortality by vessel strike of five large whales over the effective 
period of the regulations (December 2018-December 2025). The effective 
period remains unchanged from the existing regulations. Further, the 
Navy's planned activities remain unchanged; however, this final rule 
includes two additional mitigation measures and revision of two 
existing mitigation measures to further reduce the probability of 
vessel strike, as well as two additional reporting measures (described 
below in the Changes from the Proposed Rule to the Final Rule section) 
from that included in the 2020 HSTT regulations. With the exception of 
these new mitigation measures and revisions to two existing mitigation 
measures, the required mitigation and monitoring measures remain 
unchanged from the 2020 HSTT regulations.
    Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) 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, after notice and public comment, the agency makes certain findings 
and issues regulations that set forth permissible methods of taking 
pursuant to that activity, as well as monitoring and reporting 
requirements. Section 101(a)(5)(A) of the MMPA and the implementing 
regulations at 50 CFR part 216, subpart I, provide the legal basis for 
issuing this final rule and the subsequent LOAs. As directed by this 
legal authority, this final rule contains mitigation, monitoring, and 
reporting requirements.

Summary of Major Provisions Within the Final Rule

    The following is a summary of the major provisions of this final 
rule regarding the Navy's activities. Major provisions include, but are 
not limited to:
     The use of defined powerdown and shutdown zones (based on 
activity);
     Measures to reduce or eliminate the likelihood of ship 
strikes;
     Activity limitations in certain areas and times that are 
biologically important (i.e., for foraging, migration, reproduction) 
for marine mammals;
     Implementation of a Notification and Reporting Plan (for 
dead, live stranded, or marine mammals struck by a vessel); and
     Implementation of a robust monitoring plan to improve our 
understanding of the environmental effects resulting from the Navy 
training and testing activities.
    Additionally, the rule includes an adaptive management component 
that allows for timely modification of mitigation or monitoring 
measures based on new information, when appropriate.

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et

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seq.) direct the Secretary of Commerce (as delegated to NMFS) to allow, 
upon request, the incidental, but not intentional, taking of small 
numbers of marine mammals by U.S. citizens who engage in a specified 
activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are issued or, if the taking is limited to harassment, the public is 
provided with notice of the proposed incidental take authorization and 
the opportunity to review and submit comments.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other means of effecting the least practicable adverse 
impact on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such species or stocks for 
taking for certain subsistence uses (referred to in this rulemaking as 
``mitigation''); and requirements pertaining to the monitoring and 
reporting of such takings. The MMPA defines ``take'' to mean to harass, 
hunt, capture, or kill, or attempt to harass, hunt, capture, or kill 
any marine mammal. The Analysis and Negligible Impact Determination 
section below 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 indicated above and amended the definition of 
``harassment'' as applied to a ``military readiness activity.'' The 
definition of harassment for military readiness activities (section 
3(18)(B) of the MMPA) is (i) any act that injures or has the 
significant potential to injure a marine mammal or marine mammal stock 
in the wild (Level A Harassment); or (ii) any act that disturbs or is 
likely to disturb a marine mammal or marine mammal stock in the wild by 
causing disruption of natural behavioral patterns, including, but not 
limited to, migration, surfacing, nursing, breeding, feeding, or 
sheltering, to a point where such behavioral patterns are abandoned or 
significantly altered (Level B harassment). In addition, the 2004 NDAA 
amended the MMPA as it relates to military readiness activities such 
that the least practicable adverse impact analysis shall include 
consideration of personnel safety, practicality of implementation, and 
impact on the effectiveness of the military readiness activity.
    The NDAA for Fiscal Year 2019 (2019 NDAA) (Pub. L. 115-232), 
amended the MMPA to allow incidental take rules for military readiness 
activities under section 101(a)(5)(A) to be issued for up to 7 years. 
Prior to this amendment, all incidental take rules under section 
101(a)(5)(A) were limited to 5 years.
    Under the MMPA implementing regulations, incidental take 
regulations may be modified, in whole or in part, as new information is 
developed and after notice and opportunity for public comment (50 CFR 
216.105). An LOA must be withdrawn or suspended if, after notice and 
opportunity for public comment, NMFS determines that the regulations 
are not being substantially complied with, or the taking is having, or 
may have, more than a negligible impact on species or stock. (Id. at 
216.106(e)). Note, in its application, Navy relied on Sec. Sec.  
218.76, and 218.77. These sections outline the process for modification 
of an LOA without modifying the applicable incidental take regulation. 
These sections do not apply here because the Navy requested 
modification of the 2020 HSTT regulations.

Summary of Request

    On December 27, 2018, NMFS issued a 5-year final rule governing the 
taking of marine mammals incidental to Navy training and testing 
activities conducted in the HSTT Study Area (83 FR 66846; hereafter 
``2018 HSTT final rule''). Previously, on August 13, 2018, and towards 
the end of the time period in which NMFS was processing the Navy's 
request for the 2018 regulations, the 2019 NDAA amended the MMPA for 
military readiness activities to allow incidental take regulations to 
be issued for up to 7 years instead of the previous 5 years. The Navy's 
training and testing activities conducted in the HSTT Study Area 
qualify as military readiness activities pursuant to the MMPA, as 
amended by the 2004 NDAA. On March 11, 2019, the Navy submitted an 
application requesting that NMFS extend the 2018 HSTT final rule (83 FR 
66846, December 27, 2018) and associated LOAs such that they would 
cover take incidental to 7 years of training and testing activities 
instead of 5, extending the expiration date from December 20, 2023 to 
December 20, 2025. On July 10, 2020, NOAA Fisheries issued regulations 
(85 FR 41780) to govern the taking of marine mammals incidental to the 
training and testing activities conducted in the HSTT Study Area over 
the course of 7 years, effectively extending the effective period from 
December 20, 2023 to December 20, 2025.
    On March 31, 2022, NMFS received an adequate and complete 
application (2022 Navy application) from the Navy requesting that NMFS 
modify the existing regulations and LOAs to authorize two additional 
takes of large whales by serious injury or mortality by vessel strike 
over the remainder of the HSTT authorization period. The 2020 HSTT 
regulations (50 CFR part 218, subpart H) and LOAs authorize the take of 
marine mammals from the Navy's training and testing activities in the 
HSTT Study Area through December 20, 2025. These regulations and LOAs 
authorize the take of three large whales by serious injury or mortality 
by vessel strike.
    The Navy's 2022 request is based upon new information regarding 
U.S. Navy vessel strikes off the coast of Southern California. As 
described in the 2022 Navy application, in 2021, two separate U.S. Navy 
vessels struck unidentified large whales off the coast of Southern 
California on two separate occasions, one whale in June 2021 and one 
whale in July 2021. Separately, a foreign naval vessel struck two fin 
whales off the coast of Southern California in May 2021.
    In the 2022 Navy application, the Navy proposed no changes to the 
nature of the specified activities covered by the 2020 HSTT final rule. 
The Navy stated that the level of activity within and between years 
would be consistent with that previously analyzed in the 2020 HSTT 
final rule, and all activities would be conducted within the same 
boundaries of the HSTT Study Area identified in the 2020 HSTT final 
rule. The training and testing activities (e.g., equipment and sources 
used, exercises conducted) are identical to those described and 
analyzed in the 2020 HSTT final rule, and the mitigation, monitoring, 
and reporting measures are similar to those described and analyzed in 
the 2020 HSTT final rule. The only changes included in the Navy's 
request are for additional take by serious injury or mortality by 
vessel strike.
    The Navy's mission is to organize, train, equip, and maintain 
combat-ready naval forces capable of winning wars, deterring 
aggression, and maintaining freedom of the seas. This mission is 
mandated by Federal law (10 U.S.C. 8062), which ensures the readiness 
of the naval forces of the United States. The Navy executes this 
responsibility by establishing and executing training programs, 
including at-sea training and exercises, and ensuring naval forces

[[Page 4946]]

have access to the ranges, operating areas (OPAREAs), and airspace 
needed to develop and maintain skills for conducting naval activities.
    For a summary of the training and testing activities within the 
HSTT Study Area, see the Navy's previous rulemaking and LOA 
applications submitted for HSTT Phase III activities (October 13, 2017 
initial rulemaking and LOA application (hereafter ``2017 Navy 
application'') and March 11, 2019 extension rulemaking and LOA 
application (hereafter ``2019 Navy application'')) and the 2020 HSTT 
regulations that were subsequently promulgated, which can be found at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. These 
activities are deemed by the Navy necessary to accomplish military 
readiness requirements and are anticipated to continue into the 
reasonably foreseeable future. The 2022 Navy application and this rule 
cover training and testing activities that would occur over the 
remainder of the effective period of the current regulations, valid 
from the publication date of this final rule through December 20, 2025.

Summary of the Regulations

    NMFS is modifying the incidental take regulations and associated 
LOAs to cover the same Navy activities covered by the 2020 HSTT 
regulations but authorize five takes of large whales by serious injury 
or mortality by vessel strike (two takes in addition to the three takes 
authorized in the 2020 HSTT regulations). In its 2022 application, the 
Navy proposed no additional changes and explained that its training and 
testing activities, including the level of vessel use, remain 
unchanged. Nearly all mitigation, monitoring, and reporting measures 
remain unchanged from the 2020 HSTT regulations (85 FR 41780, July 10, 
2020) with the exception of two additional mitigation measures (see the 
Mitigation Measures section of this final rule), revision of two 
existing mitigation measures (see the Mitigation Measures section of 
this final rule), and two additional reporting measures resulting from 
discussions between the Navy and NMFS (see the Reporting section of 
this final rule).
    In response to the Navy's request, we focus our analysis on the new 
information related to vessel strike. We also review any new 
information that may be pertinent to our analysis of the impacts from 
all other activities that comprise Navy's specified activity, and our 
analysis of mitigation, monitoring, and reporting. Where there is any 
new information pertinent to the descriptions, analyses, or findings 
required to authorize the incidental take for military readiness 
activities under MMPA section 101(a)(5)(A), that information is 
provided in the appropriate sections below. Where there is no new 
information or any new information does not change our previous 
analysis or findings, we indicate as such and refer the reader to the 
original analysis in the 2018 HSTT proposed and final rule, 2020 HSTT 
final rule or the 2019 HSTT Final Environmental Impact Statement 
(FEIS)/Overseas Environmental Impact Statement (OEIS).
    After reviewing all new information and as discussed below, we 
largely find that our previous analyses and findings remain current and 
applicable. For vessel strike, we provide a new analysis and authorize 
two additional takes of large whales, for a total of five takes by 
serious injury or mortality by vessel strike over the 7-year period. We 
authorize these additional takes after analyzing the best available 
scientific information and after considering the effects of the entire 
specified activity and the total taking as required by MMPA section 
101(a)(5)(A). When setting forth the permissible methods of taking 
pursuant to the activity and other means of effecting the least 
practicable adverse impact on the species or stock, we require new and 
modified mitigation and also consider whether to require any new or 
modified mitigation for the entire specified activity.
    The regulatory language included at the end of this final rule, 
which is published at 50 CFR part 218, subpart H, remains largely the 
same as that under the HSTT 2020 regulations, except for a small number 
of technical changes related to the Navy's 2022 request, new and 
revised mitigation measures, and two new reporting measures. Therefore, 
in this final rule, we refer the reader to complete analyses described 
in the 2018 HSTT final rule or an updated analysis in the 2020 HSTT 
final rule, where appropriate.
    Below is a list of the regulatory documents referenced in this 
final rule. The list indicates the short name by which the document is 
referenced in this final rule as well as the full titles of the cited 
documents. All of the documents can be found at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities and http://www.hstteis.com/.
     NMFS June 26, 2018, Hawaii-Southern California Training 
and Testing (HSTT) proposed rule (83 FR 29872; 2018 HSTT proposed 
rule);
     NMFS December 27, 2018, Hawaii-Southern California 
Training and Testing (HSTT) final rule (83 FR 66846; 2018 HSTT final 
rule);
     NMFS September 13, 2019, Hawaii-Southern California 
Training and Testing (HSTT) proposed rule (84 FR 48388; 2019 HSTT 
proposed rule);
     NMFS July 10, 2020, Hawaii-Southern California Training 
and Testing (HSTT) final rule (85 FR 41780; 2020 HSTT final rule);
     NMFS October 3, 2023, Hawaii-Southern California Training 
and Testing (HSTT) proposed rule (88 FR 68290; 2023 HSTT proposed 
rule);
     Navy October 13, 2017, MMPA rulemaking and LOA application 
(2017 Navy application);
     Navy March 11, 2019, MMPA rulemaking and LOA extension 
application (2019 Navy application);
     Navy March 31, 2022, MMPA rulemaking and LOA revision 
application (2022 Navy application); and
     October 26, 2018, Hawaii-Southern California Training and 
Testing (HSTT) Final Environmental Impact Statement/Overseas 
Environmental Impact Statement (FEIS/OEIS) (2018 HSTT FEIS/OEIS).

Description of the Specified Activity

    The Navy requested authorization to take marine mammals incidental 
to conducting training and testing activities. The Navy has determined 
that acoustic and explosives stressors are most likely to result in 
impacts on marine mammals that could rise to the level of harassment. 
In addition to take by harassment, the Navy has determined that vessel 
movement may result in serious injury or mortality to marine mammals. 
Detailed descriptions of these activities are provided in chapter 2 of 
the 2018 HSTT FEIS/OEIS and in the 2017 Navy application.

Overview of Training and Testing Activities

    The Navy routinely trains in the HSTT Study Area in preparation for 
national defense missions. Training and testing activities and 
components covered in the 2022 Navy application are described in detail 
in the Overview of Training and Testing Activities sections of the 2018 
HSTT proposed rule, the 2018 HSTT final rule, and chapter 2 
(Description of Proposed Action and Alternatives) of the 2018 HSTT 
FEIS/OEIS (http://www.hstteis.com/). Each military training and testing 
activity described meets mandated Fleet requirements to deploy ready 
forces. The Navy proposed no changes to the specified activities

[[Page 4947]]

described and analyzed in the 2018 HSTT final rule and subsequent 2020 
HSTT final rule. The boundaries of the HSTT Study Area (see figure 2-1 
of the 2019 Navy application); the dates and duration of the 
activities; and the training and testing activities (e.g., equipment 
and sources used, exercises conducted) analyzed in this final rule are 
identical to those described and analyzed in the 2020 HSTT final rule 
and therefore, are not repeated herein. Please see the 2020 HSTT final 
rule for more information. The manner of vessel movement presented in 
this final rule is also identical to that analyzed in the 2020 HSTT 
final rule.

Vessel Strike

    Vessel strikes are not specific to any particular training or 
testing activity but rather, a limited, sporadic, and incidental result 
of Navy vessel movement within the HSTT Study Area. Vessel strikes from 
commercial, recreational, and military vessels are known to seriously 
injure and occasionally kill cetaceans (Abramson et al. 2011; Berman-
Kowalewski et al. 2010; Calambokidis, 2012; Douglas et al. 2008; 
Laggner, 2009; Lammers et al. 2003; Van der Hoop et al. 2012; Van der 
Hoop et al. 2013; Crum et al. 2019), although reviews of the literature 
on vessel strikes mainly involve collisions between commercial vessels 
and whales (Jensen and Silber, 2003; Laist et al. 2001). Vessel speed, 
size, and mass are all important factors in determining both the 
potential likelihood and impacts of a vessel strike to marine mammals 
(Conn and Silber, 2013; Gende et al. 2011; Silber et al. 2010; 
Vanderlaan and Taggart, 2007; Wiley et al. 2016). For large vessels, 
speed and angle of approach can influence the severity of a strike.
    Navy vessels transit at speeds that are optimal for fuel 
conservation or to meet training and testing requirements. Small craft 
(for purposes of this analysis, less than 18 meters (m) in length) have 
much more variable speeds (0-50+ knots (kn; 0-92.6 kilometers (km) per 
hour), dependent on the activity). Submarines generally operate at 
speeds in the range of 8-13 kn (14.8-24.1 km per hour), and the average 
speed of large Navy ships range between 10 and 15 kn (18.5 and 27.8 km 
per hour). While these speeds are considered averages and 
representative of most events, some vessels need to operate outside of 
these parameters for certain times or during certain activities. For 
example, to produce the required relative wind speed over the flight 
deck, an aircraft carrier engaged in flight operations must adjust its 
speed through the water accordingly. Also, there are other instances 
when vessels would be dead in the water or moving slowly ahead to 
maintain steerage, such as launch and recovery of a small rigid hull 
inflatable boat; vessel boarding, search, and seizure training events; 
or retrieval of a target. There are a few specific events, including 
high-speed tests of newly constructed vessels, where vessels would 
operate at higher speeds. By comparison, this is slower than most 
commercial vessels where full speed for a container ship is typically 
24 kn (44.4 km per hour; Bonney and Leach, 2010).
    Large Navy vessels (greater than 18 m in length) within the 
offshore areas of range complexes and testing ranges operate 
differently from commercial vessels in ways that may reduce the 
probability of whale collisions. Surface ships operated by or for the 
Navy have multiple personnel assigned to stand watch at all times when 
a ship or surfaced submarine is moving through the water (underway). A 
primary duty of personnel standing watch on surface ships is to detect 
and report all objects and disturbances sighted in the water that may 
indicate a threat to the vessel and its crew, such as debris, a 
periscope, surfaced submarine, or surface disturbance. Per vessel 
safety requirements, personnel standing watch also report any marine 
mammals sighted in the path of the vessel as a standard collision 
avoidance procedure. All vessels proceed at a safe speed so they can 
take proper and effective action to avoid a collision with any sighted 
object or disturbance and can be stopped within a distance appropriate 
to the prevailing circumstances and conditions. As described in the 
Standard Operating Procedures section, the Navy utilizes Lookouts to 
avoid collisions, and Lookouts are also trained to spot marine mammals 
so that vessels may change course or take other appropriate action to 
avoid collisions. Should a vessel strike occur, we consider that it 
would likely result in incidental take in the form of serious injury 
and/or mortality and, accordingly, for the purposes of the analysis, we 
assume that any vessel strike would result in serious injury or 
mortality.
    The Navy proposed no changes to the nature of the specified 
activities, the training and testing activities, the manner of vessel 
movement, the speeds at which vessels operate, the number of vessels 
that would be used during various activities, or the locations in which 
Navy vessel activity would be concentrated within the HSTT Study Area 
described in the 2018 HSTT final rule and referenced in the 2020 HSTT 
final rule.

Vessel Movement

    Vessels used as part of the planned activities include ships, 
submarines, unmanned vessels, and boats ranging in size from small, 22 
feet (ft; 7 m) rigid hull inflatable boats to aircraft carriers with 
lengths up to 1,092 ft (333 m). The average speed of large Navy ships 
ranges between 10 and 15 kn (18.5 and 27.8 km per hour) and submarines 
generally operate at speeds in the range of 8-13 kn (14.8-24.1 km per 
hour) while a few specialized vessels can travel at faster speeds. 
Small craft (for purposes of this analysis, less than 18 m in length) 
have much more variable speeds (0-50+ kn (0-92.6 km per hour), 
dependent on the activity) but generally range from 10 to 14 kn (18.5 
to 25.9 km per hour). From unpublished Navy data, average median speed 
for large Navy ships in the HSTT Study Area from 2011-2015 varied from 
5-10 knots (kn; 9.2-18.5 km per hour) with variations by ship class and 
location (i.e., slower speeds close to the coast). While these speeds 
for large and small craft are representative of most events, some 
vessels need to temporarily operate outside of these parameters. 
Typical speed of Navy vessels in HSTT core high use areas from 2014-
2018 were between 10 and 15 kn (18.5 and 27.8 km per hour; Starcovic 
and Mintz 2021). This core area is a region including the approaches to 
San Diego, and immediate offshore areas west of San Diego, centered 
north and south of San Clemente Island. A full description of Navy 
vessels that are used during training and testing activities can be 
found in the 2017 Navy application and chapter 2 (Description of 
Proposed Action and Alternatives) of the 2018 HSTT FEIS/OEIS.
    The number of Navy vessels used in the HSTT Study Area varies based 
on military training and testing requirements, deployment schedules, 
annual budgets, and other dynamic factors. Most training and testing 
activities involve the use of vessels. These activities could be widely 
dispersed throughout the HSTT Study Area but would typically be 
conducted near naval ports, piers, and range areas. Navy vessel traffic 
would be especially concentrated near San Diego, California and Pearl 
Harbor, Hawaii. Based on historical data, we anticipate the annual 
number of at-sea hours by U.S. Navy vessels in the HSTT action area 
will be around 26,800 hours per year (Starcovic and Mintz 2021). We 
expect that about 25 percent of this vessel activity would occur within 
the Hawaii Range Complex

[[Page 4948]]

(HRC) and 75 percent within the Southern California Range Complex 
(SOCAL; Mintz 2016). There is no seasonal differentiation in Navy 
vessel use because of continual operational requirements from Combatant 
Commanders. The majority of large vessel traffic occurs between the 
installations and the OPAREAs. The transit corridor, notionally defined 
by the great circle route (e.g., shortest distance) from San Diego to 
the center of the HRC, as depicted in the 2018 HSTT FEIS/OEIS, is 
generally used by ships transiting between SOCAL and HRC. While in 
transit, ships and aircraft would, at times, conduct basic and routine 
unit-level activities such as gunnery, bombing, and sonar training and 
maintenance. Of note, support craft would be more concentrated in the 
coastal waters in the areas of naval installations, ports, and ranges. 
Activities involving vessel movements occur intermittently and are 
variable in duration, ranging from a few hours up to weeks. More 
information on Navy and non-Navy vessel traffic patterns in the HSTT 
Study Area may be found in several studies prepared by the Navy 
(Starcovic and Mintz 2021; Mintz, 2016; Mintz and Filadelfo, 2011; 
Mintz, 2012; Mintz and Parker, 2006).

Foreign Navies

    In addition, we note that in some cases, foreign militaries may 
participate in U.S. Navy training or testing activities in the HSTT 
Study Area. The Navy does not consider these foreign military 
activities as part of the ``specified activity'' under the MMPA, and 
NMFS defers to the applicant to describe the scope of its request for 
an authorization.
    The participation of foreign navies varies from year to year, but 
overall is infrequent compared with Navy's total training and testing 
activities. The most significant joint training event is the Rim of the 
Pacific (RIMPAC), a multi-national training exercise held every-other-
year primarily in the HRC. The participation level of foreign military 
vessels in U.S. Navy-led training or testing events within the HRC and 
within SOCAL differs greatly between RIMPAC and non-RIMPAC years. For 
example, in 2019 (a non-RIMPAC year), there were 0.1 foreign navy 
surface vessel at-sea days (i.e., 1 day = 24 hours) within HRC and 20 
foreign navy at-sea days within SOCAL (Navy 2021). Out of 56 U.S.-led 
training events in 2019, 4 involved foreign navy vessels, with an 
average time per event of 8.7 hours. In 2020, a RIMPAC year, foreign 
vessels participating in U.S. Navy-led events accounted for 32 at-sea 
days in the HRC from August through September (some of this activity 
occurred after the RIMPAC exercise). During RIMPAC 2022, foreign 
vessels operated and/or transited through the HRC for 576 hours (24 
days). In 2023 (another non-RIMPAC year), there was no foreign vessel 
participation within SOCAL. Even in a RIMPAC year, the days at sea for 
foreign militaries engaged in a Navy-led training or testing activity 
accounts for a small, but variable, percentage compared to the U.S. 
Navy activities. For instance, the 2020 foreign military participation 
(a RIMPAC-year) was 1.5 percent of the U.S. Navy's average days at sea 
(32 days out of an estimated 2,056 days at sea). During RIMPAC 2024, 
twenty-five foreign surface vessels participated for a combined 5,000 
hours in U.S.-led training events. Therefore, foreign surface vessel 
activity is estimated to conservatively account for up to 10 percent of 
the U.S. Navy's annual at sea time in HSTT (205 days out of an 
estimated 2,056 days at sea).
    According to the U.S. Navy, consistent with customary international 
law, when a foreign military vessel participates in a U.S. Navy 
exercise within the U.S. territorial sea (i.e., 0 to 12 nautical miles 
(nmi; 0 to 22.2 km) from shore), the U.S. Navy will request that the 
foreign vessel follow the U.S. Navy's mitigation measures for that 
particular event. When a foreign military vessel participates in a U.S. 
Navy exercise beyond the U.S. territorial sea but within the U.S. 
Exclusive Economic Zone, the U.S. Navy will encourage the foreign 
vessel to follow the U.S. Navy's mitigation measures for that 
particular event (Navy 2022a; Navy 2022b). In either scenario (i.e., 
both within and beyond the territorial sea), U.S. Navy personnel will 
provide the foreign vessels participating with a description of the 
mitigation measures to follow.
    According to the U.S. Navy, the May 2021 vessel strike of two fin 
whales by an Australian navy vessel did not occur while that vessel was 
participating in a U.S. Navy-led training exercise. The Royal 
Australian Navy vessel was adhering to its standard operating 
procedures at the time of the strike. The Royal Australian Navy 
provided a report of the incident, which is discussed below to inform 
our analysis.
    NMFS analyzes the effects of these foreign military activities. 
First, effects of all past foreign military activities are captured in 
the baseline for the analysis, through marine mammal abundance 
estimates and population trends found in the Stock Assessment Reports 
(SARs). Second, NMFS considers foreign military activities, including 
recent strikes, qualitatively in this final rule. For instance, in 
preparing this rulemaking, NMFS and the U.S. Navy discussed the nature, 
frequency, and control over joint or U.S. Navy-led training and testing 
activities with foreign entities to identify opportunities to encourage 
foreign militaries to adopt mitigation. NMFS and the U.S. Navy examined 
the Royal Australian Navy 2021 strike report for any lessons that could 
inform U.S. Navy strike mitigation. NMFS considered the Royal 
Australian Navy strikes along with other recent U.S. Navy strikes to 
determine whether these strikes indicate an increased risk of strike by 
the U.S. Navy in this region during the early summer months. NMFS also 
considered the species struck in this incident, fin whales, along with 
other literature, when considering the likelihood of certain species to 
be struck by the U.S. Navy. NMFS considered the fact that two fin 
whales were struck by the Royal Australian Navy qualitatively when 
considering other fin whale population and mortality trends, as well as 
the authorized take, as part of the negligible impact analysis.
    This final rule includes a new reporting measure that requires that 
the Navy's annual HSTT reports shall include confirmation 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 
U.S. Navy's use of sonar and explosives, would not cause 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. This new reporting 
measure will allow NMFS to ensure that its analysis remains valid.

Standard Operating Procedures

    For training and testing to be effective, personnel must be able to 
safely use their sensors and weapon systems as they are intended to be 
used in a real-world situation and to their optimum capabilities. While 
standard operating procedures (SOPs) are designed for the safety of 
personnel and equipment and to ensure the success of training and 
testing activities, their implementation often yields additional 
benefits on environmental, socioeconomic, public health and safety, and 
cultural resources. Because SOPs are essential to safety and mission 
success, the Navy considers them to be part of the proposed activities 
under the National Environmental Policy Act

[[Page 4949]]

(NEPA) and included them in the environmental analysis. We consider 
SOPs as part of Navy's specified activity for the purposes of MMPA but 
also, where procedures are utilized (even in part) to reduce impacts to 
marine mammal species and Navy's commitment to follow the measures are 
practicable, certain SOPs may also be required as mitigation. Details 
on SOPs were provided in the 2018 HSTT proposed rule; please see the 
2018 HSTT proposed rule, the 2017 Navy application, and chapter 2 
(Description of Proposed Action and Alternatives) of the 2018 HSTT 
FEIS/OEIS for more information.
    As stated in its 2022 application, in 2018, the Navy updated its 
SOPs related to vessel safety to incorporate revised procedures 
regarding Lookouts for certain ship classes as per the 2021 Surface 
Ship Navigation Department Organization and Regulations Manual 
(NAVDORM). The 2021 NAVDORM requires the use of three Lookouts on Navy 
cruisers and destroyers as compared to the previous requirement of one 
Lookout when a vessel was underway and not engaged in sonar training or 
testing. However, as discussed in the Mitigation Measures section 
below, the Navy informed NMFS that requiring the additional Lookouts as 
mitigation is not practicable because this SOP may change in response 
to manning issues and national security needs. Further, since 
submission of its 2022 application, the Navy has updated its Lookout 
Training Handbook and implemented other training improvements, as 
described in the Mitigation Measures section (September 2022).

Comments and Responses

    We published a proposed rule in the Federal Register on October 3, 
2023 (88 FR 68290), with a 45-day comment period. That notice 
described, in detail, Navy's request for modification of the 2020 HSTT 
final rule and LOAs, new information regarding the occurrence of large 
whale strikes by naval vessels in the southern California portion of 
the HSTT Study Area and NMFS' proposal to authorize two additional 
takes of large whales by serious injury or mortality. In that notice, 
we requested public input on the proposed promulgation of modified 
regulations and associated LOAs for the Navy governing this additional 
incidental taking of marine mammals. During the 45-day comment period, 
we received 20 comment submissions. Of this total, one submission was 
from a non-governmental organization (NGO) and the remainder were from 
private citizens. NMFS has reviewed and considered all public comments 
received on the proposed rule and issuance of the LOAs. All substantive 
comments and our responses are described below. We organize our comment 
responses by major categories.

Take Estimates

    Comment 1: A commenter recommended ensuring that any modifications 
to existing regulations or authorizations are based on recent and 
rigorous scientific evaluations. This can be achieved by conducting 
regular environmental impact assessments to account for changes in 
marine mammal populations and habitat conditions.
    Response: NMFS concurs with the commenter that modifications to 
existing regulations or authorizations must be based on rigorous 
scientific evaluations. NMFS has conducted a rigorous scientific 
evaluation in the promulgation of this rulemaking and has used the best 
available science to inform its analysis. These final regulations and 
LOAs include reporting provisions to ensure compliance and that the 
most value is obtained from the required monitoring. Monitoring results 
are considered annually through the adaptive management process 
described in the Adaptive Management section herein. Further, 
incidental take authorizations for military readiness activities can be 
effective for no more than 7 years. Therefore, at minimum, NMFS must 
reconduct its analysis every 7 years, and in doing so, it considers 
changes in marine mammal populations and habitats in its analyses. 
However, during the effective period of an LOA(s), if NMFS were to find 
that the Navy's activities are having more than a negligible impact on 
a species or stock, NMFS is required to withdraw or suspend the LOA(s) 
for a certain time (16 U.S.C. 1371(a)(5)(B)).
    Comment 2: A commenter stated that the 2022 Navy application is 
based on 50 CFR 216.015 [the commenter is likely referring to section 
216.105], which allows incidental take regulations to ``be modified, in 
whole or in part, as new information is developed.'' The commenter 
asserted that the only ``new information'' in the 2022 application is 
the information that the Navy has already reached its 7-year take limit 
and that failure to meet our own standards does not constitute ``new 
information'' in the sense of 50 CFR 216.015. The commenter stated that 
``new information'' for this purpose would be either (1) evidence that 
allowing two additional takes (and relaxing mitigation procedures as 
requested in the application) during this time period will have no 
impact on threatened cetacean populations or (2) a dramatic increase in 
the level of military activity in HSTT.
    Response: The MMPA provides for the authorization of incidental 
take caused by specified activities at the request of an applicant, 
provided certain findings are made. The law directs NMFS to process 
adequate and complete applications for incidental take authorization, 
and issue the authorization provided all statutory findings and 
requirements, as well as all associated legal requirements, are met. 
Under 50 CFR 216.105, as new information is developed, through 
monitoring, reporting, or research, the regulations may be modified, in 
whole or in part, after notice and opportunity for public review. On 
March 31, 2022, NMFS received an adequate and complete application from 
the Navy requesting that NMFS modify the existing regulations and LOAs 
to authorize two additional takes of large whales by serious injury or 
mortality by vessel strike over the remainder of the HSTT regulatory 
period based on probabilities derived from a Poisson distribution using 
new vessel strike data between 2009-2021 in the HSTT Study Area, as 
well as historical at-sea days in the HSTT Study Area from 2009-2015 
and estimated at-sea days for the period from 2016 to 2025, informed by 
monitoring and reporting. NMFS independently analyzed the request based 
on updated vessel strike data and days-at-sea, as well as using updated 
probability methodology, and also determined that the strike of up to 
two large whales could occur over the remaining duration of the 
regulations. NMFS, following its own analysis and proposed rule, has 
determined it is appropriate to promulgate a revised final rule and 
LOAs pursuant to 16 U.S.C. 1371(a)(5)(A) and 50 CFR 216.105.
    Comment 3: A commenter stated that Kuehne et al. (2020), referenced 
in the 2023 HSTT proposed rule (88 FR 68290, October 3, 2023), 
indicates that noise from Navy aircraft penetrates more deeply into the 
water than the Navy or NMFS considered in their analyses. The commenter 
stated that the study found that noise from aircraft can permeate the 
water to at least 30 m and that the detected noise level (134  3 dB re 1 [mu]Pa rms) exceeds volumes that can cause behavioral 
changes in marine mammals (Houser et al. 2013; Kastelein et al. 2012; 
Kuehne et al. 2020; Williams et al. 2002). The commenter asserted that, 
therefore, the Navy's reliance on this paper to assert that aircrafts 
do not impact marine mammals is misplaced, and the proposed rule's 
dismissal of the

[[Page 4950]]

study because it ``did not include behavioral observations of wildlife, 
and the authors' conclusions about potential impacts to wildlife were 
unsupported by data from the study'' ignores the valid bases for these 
conclusions.
    Response: NMFS disagrees with the commenter that Kuehne et al. 
(2020) shows impacts to marine mammals from Navy's HSTT activities that 
were not considered by NMFS and the Navy in their respective analyses. 
As stated in the comment, the strongest one-second window of underwater 
sound measured by Kuehne et al. (2020) was 134  3 dB RMS re 
1 [mu]Pa rms at 30 m below the sea surface. While sound levels between 
the hydrophone and the surface may have been stronger than those 
measured at 30 m (Kuehne et al. 2020), for the reasons discussed in the 
2023 HSTT proposed rule, there is no new information presented in this 
study to indicate that exposures closer to the surface or in air would 
have resulted in behavioral responses that would qualify as take by 
Level B harassment.
    We conclude that the information presented in Kuehne et al. (2020) 
does not reveal effects of the action on marine mammals in a manner or 
to an extent not already considered. We reiterate that NMFS reviewed 
the Navy's analysis and conclusions that aircraft noise will not result 
in incidental take of marine mammals and finds the analysis and 
conclusions remain complete and supportable, as stated in the 2018 HSTT 
final rule and in the 2023 HSTT proposed rule (88 FR 68290, October 3, 
2023). Please see section 3.7 (Marine Mammals) of the 2018 HSTT FEIS/
OEIS for additional information. Of note, even if the sound level in 
the water were to exceed the Level B harassment threshold, a marine 
mammal would need to cross the path of the aircraft while the animal is 
relatively close to the surface in order for a take to occur, which is 
unlikely.
    In addition to Kuehne et al. (2020), the commenter referenced 
several other studies that it described as indicating that other Navy 
activities in the HSTT Study Area may affect listed species to an 
extent not previously considered. These studies include Goldbogen et 
al. (2013), Pirotta et al. (2019), Pirotta et al. (2021), Pirotta et al 
(2022), Simonis et al. (2020), Southall et al. (2019), Southall et al. 
(2021), and Szesciorka et al. (2019). NMFS considered Pirotta et al. 
(2021), Pirotta et al. (2022), and Southall et al. (2021) in its 2023 
HSTT proposed rule (88 FR 68290, October 3, 2023). NMFS considered 
Goldbogen et al. (2013) in the 2018 HSTT proposed rule (83 FR 29872, 
June 26, 2018) and 2018 HSTT final rule (83 FR 66846, December 27, 
2018), and NMFS considered Southall et al. (2019) in the 2019 HSTT 
proposed rule (84 FR 48388, September 13, 2019). Pirotta et al. (2019) 
found that environmental changes could severely affect a population's 
vital rates, but that, depending on the context of a disturbance, 
individuals were tolerant of anthropogenic disturbance. Simonis et al. 
(2020) correlated strandings in the Mariana islands with naval 
activities. NMFS is aware of this study and has considered it along 
with global information related to the correlation of sonar with 
strandings in our analysis. In a case study of a close vessel encounter 
with a blue whale, Szesciorka et al. (2019) noted that the ship's 
reduced speed (i.e., 11.3 kn (20.9 km per hour)) may have played a role 
by giving the whale enough time to respond to the nearby vessel and 
that higher vessel speeds increase the risk that a whale could have 
been struck at the surface or get close enough to the ship's draft that 
the propeller suction effect created by the ship's hydrodynamic flow 
could pull the whale toward the hull. Additionally, feeding whales may 
be distracted and thus be less capable of detecting and avoiding 
approaching vessels (Szesciorka et al. 2019). NMFS determined that the 
information presented in these studies does not substantively affect 
our analysis of impacts on marine mammals and their habitat that 
appeared in the 2023 HSTT proposed rule, all of which remains 
applicable and valid for our assessment of the effects of the Navy's 
activities during the 7-year period of this final rule. Please see 
NMFS' response to Comment 14 regarding vessel speed restrictions.
    Comment 4: A commenter expressed support for Navy use of marine 
mammals for military purposes through its Marine Mammal Program. 
However, the commenter stated that to ``take'' mammals simply as a 
training opportunity via severe injury or mortality is unethical and to 
allow the killing of innocent animals as cross-fire or training 
shouldn't be tolerated.
    Response: The actions the Navy takes through its Marine Mammal 
Program are outside the scope of this action; we note that no animals 
are intentionally exposed to serious injury or mortality through that 
program. For additional information about the Navy's Marine Mammal 
Program, please see the Navy's website at https://www.niwcpacific.navy.mil/About/Departments/Intelligence-Surveillance-and-Reconnaissance/Marine-Mammal-Program/.
    Comment 5: A commenter stated that the recent whale deaths indicate 
that (1) NMFS' earlier assumptions that vessel strikes would be 
unlikely and easily detected if they did occur were proven wrong, (2) 
vessel strikes are occurring at rates well-above that analyzed in NMFS' 
analyses, (3) whales cannot avoid vessel strike at the level NMFS 
assumed in issuing the regulations, (4) and that sonar affects blue 
whales in ways not adequately considered.
    Response: In the 2018 HSTT final rule, 2020 HSTT final rule, and 
2023 HSTT proposed rule, NMFS described why a strike by a Navy vessel 
is unlikely in comparison to a strike by a non-Navy vessel, and that, 
overall, it is unlikely that the Navy would hit a large whale for these 
reasons. However, even in consideration of these factors that make 
vessel strike unlikely, given the history of vessel strike by the U.S. 
Navy in the HSTT Study Area, NMFS, in the 2018 and 2020 HSTT final 
rules concluded that vessel strikes could occur and that authorization 
of three takes by vessel strike was appropriate. Therefore, NMFS 
disagrees that the recent vessel strikes disprove NMFS' assumption that 
vessel strikes would be unlikely.
    To date, NMFS is aware of three confirmed vessel strikes of large 
whales by U.S. Navy vessels during the current regulatory period. 
Therefore, the strikes that have occurred to date have been within what 
NMFS anticipated could occur, though, NMFS' current analysis suggests 
that two additional strikes may occur during the current regulatory 
period based on the best available scientific information since 
promulgation of the 2020 HSTT final rule.
    NMFS further disagrees that the recent vessel strikes disprove 
NMFS' assumption that vessel strikes would be detected if they did 
occur. As demonstrated by the June 2021, July 2021, and May 2023 U.S. 
Navy strikes, NMFS is confident that whales struck by Navy vessels are 
detected and reported, and Navy strikes are the numbers used in NMFS' 
analysis to support the authorized number of strikes. Navy ships have 
multiple Lookouts, including on the forward part of the ship that can 
visually detect a hit whale (which has occasionally occurred), in the 
unlikely event ship personnel do not feel the strike. The Navy's strict 
internal procedures and mitigation requirements include reporting of 
any vessel strikes of marine mammals, and the Navy's discipline, 
extensive training (not only for detecting marine mammals but for 
detecting and reporting any potential navigational obstruction), and 
strict

[[Page 4951]]

chain of command give NMFS a high level of confidence that all strikes 
are reported. Accordingly, NMFS is confident that the information used 
to support the analysis is accurate and complete. Regarding the 2021 
Royal Australian Navy vessel strikes, while the U.S. Navy cannot 
speculate on the configurations of other ships bows and even sonar dome 
specifications (that may be at the bow), the Navy believes it would be 
implausible for a marine mammal to become lodged on the sonar dome of a 
U.S. Navy ship and remain undetected due to a technological standard 
operating procedure.
    While the 2018 HSTT final rule, the 2020 HSTT final rule, and this 
final rule include mitigation to reduce the potential for vessel 
strike, NMFS neither states nor implies vessel strike avoidance of a 
particular ``level''. However, it is important that NMFS and the Navy 
consider the new information regarding vessel strikes in southern 
California consistent with 50 CFR 216.105(c). Consideration of this new 
information in an updated analysis allows NMFS to reassess its 
negligible impact determination and to determine whether additional 
potential mortality would still constitute a negligible impact on the 
potentially affected stocks, as it has determined would be the case 
here.
    The commenter referenced several studies related to blue whales and 
sonar. Please see NMFS' response to Comment 3.
    Comment 6: A commenter stated that NMFS should deny the Navy's 
request for authorization of two additional takes of large whales by 
vessel strike because for at least two of the impacted marine mammal 
stocks (Eastern North Pacific stock of blue whale and Central America/
Southern Mexico--California/Oregon/Washington stock of humpback whale) 
mortality and serious injury already exceeds potential biological 
removal (PBR). The commenter stated that NMFS' reasoning for 
authorizing the take amounts to ``take by a thousand cuts'' and defies 
the stated purpose and objectives of the MMPA.
    A commenter stated that NMFS may allow take of marine mammals 
incidental to military readiness activities only if the taking will 
have a ``negligible impact'' on an affected species or stock. The 
commenter further stated that as one court has explained, ``[b]ecause 
any mortality level that exceeds PBR will not allow the stock to reach 
or maintain its optimum sustainable population (`OSP'), such a 
mortality level could not be said to have only a `negligible impact' on 
the stock.'' (See Conservation Council for Hawai'i v. Nat'l Marine 
Fisheries Serv., 97 F. Supp. 3d 1210, 1225 (D. Haw. 2015); see also 54 
FR 40338, 40341, 40342 (Sept. 29, 1989) (``In order to make a 
negligible impact finding, the proposed incidental take must not 
prevent a depleted population from increasing toward its OSP.'')). 
Indeed, NMFS itself has previously recognized that when mortality of a 
species is above its PBR, ``a negligible impact finding under section 
101(a)(5)(A) cannot be made'' (61 FR 54,157, October 17, 1996).
    Response: The commenter is correct that PBR for the Eastern North 
Pacific stock of blue whales and the Central America/Southern Mexico--
California/Oregon/Washington stock of humpback whales is currently 
exceeded. However, NMFS is not authorizing take by mortality of the 
Central America/Southern Mexico--California/Oregon/Washington stock of 
humpback whales. In this final rule, NMFS is authorizing take of the 
Mainland Mexico-CA/OR/WA stock of humpback whale, and PBR is not 
exceeded for this stock. A stock's PBR is part of the best scientific 
information available and therefore, is considered in the negligible 
impact determination (see Conservation Council for Hawai'i v. Nat'l 
Marine Fisheries Serv., 97 F. Supp. 3d 1210, 1228 (D. Haw. 2015)). 
However, exceedance of PBR does not inherently imply that a negligible 
impact determination cannot be made for an authorization that includes 
mortality or serious injury (M/SI) of that stock. As explained in the 
Serious Injury or Mortality subsection of the Analysis and Negligible 
Impact Determination section of the 2018 HSTT final rule and 2020 HSTT 
final rule, and referenced in the same section of this final rule, in 
the commercial fisheries setting for Endangered Species Act (ESA)-
listed marine mammals (which is similar to the non-fisheries incidental 
take setting, in that a negligible impact determination is required 
that is based on the assessment of take caused by the activity being 
analyzed), NMFS may find the impact of the authorized take from a 
specified activity to be negligible even if total human-caused 
mortality exceeds PBR, if the authorized mortality is less than 10 
percent of PBR and management measures are being taken to address 
serious injuries and mortalities from the other activities causing 
mortality (i.e., other than the specified activities covered by the 
incidental take authorization in consideration). When those 
considerations are applied in the section 101(a)(5)(A) context here, 
the authorized lethal take (0.14 annually) of blue whales from the 
Eastern North Pacific stock is less than 10 percent of PBR (4.1) and 
there are management measures in place to address the mortality and 
serious injury from the activities other than those the Navy is 
conducting. For the complete discussion of how NMFS carefully 
considered potential mortalities from the Navy's activities in light of 
PBR levels, including an explanation for why mortality above PBR will 
not necessarily induce population-level non-negligible impacts, see the 
discussion in the Analysis and Negligible Impact Determination section 
of this rule, the 2020 HSTT final rule, and the 2018 HSTT final rule.
    The commenter references a 1996 NMFS notice of receipt and request 
for comments (61 FR 54,157; October 17, 1996) that stated that a 
negligible impact finding under section 101(a)(5)(A) could not be made 
where PBR for the North Atlantic right whale stock was 0.4. The method 
that NMFS has articulated herein to evaluate negligible impact of 
potential mortality was adopted in 1999 to evaluate negligible impact 
pursuant to MMPA section 101(a)(5)(E). NMFS uses these same criteria 
adopted in 1999 to inform (i.e., it is not the sole factor considered) 
our negligible impact analysis of potential mortality under section 
101(a)(5)(A).
    The 1996 decision that a negligible impact determination could not 
be made was regarding a request for take by mortality of North Atlantic 
right whale (61 FR 54,157; October 17, 1996)). PBR for North Atlantic 
right whale at that time was 0.4. If NMFS were to apply its current 
method for evaluating negligible impact of potential mortality to that 
request, the results would suggest that take by mortality should not be 
authorized (though again, the PBR evaluation is not the sole factor 
considered).
    Comment 7: A commenter stated that the Navy and NMFS must consider 
serious injury and mortality that results from joint training exercises 
the Navy engages in with foreign nations as ``take'' under the 
regulations and that NMFS must reexamine the impacts of the Navy's full 
suite of activities (including joint activities with foreign fleets) on 
marine mammals using the best available science. In the proposed rule, 
NMFS states that ``[a]ccording to the U.S. Navy, the May 2021 vessel 
strike of two fin whales by an Australian navy vessel did not occur 
while that vessel was participating in a U.S. Navy-led training 
exercise. The Royal Australian Navy vessel was adhering to its standard 
operating procedures at the time of the strike.'' The commenter stated 
that this contradicts coverage of

[[Page 4952]]

the incident, including by the Navy Times/AP that reported: ``[t]he 
Sydney has been holding joint exercises with the U.S. Navy in the area 
since early April'' (The Navy Times, 2021).
    The commenter stated that elsewhere in the rule, NMFS appears to 
say that regardless of whether it considered vessel strikes that 
occurred during joint training or not, NMFS lets the Navy decide what 
activities it requests authorization for, and there is no reasoned 
explanation provided for this position. These joint activities led by 
the U.S. Navy pose serious threats to marine mammals, kill whales, and 
should be included as specified activities. The commenter recommended 
that NMFS not ``defer to the applicant to describe the scope of its 
request for an authorization.''
    Response: Under the MMPA, only a U.S. Citizen may request NMFS 
authorize the incidental take of marine mammals (16 U.S.C. 
1371(a)(5)(A)). Further, the MMPA requires NMFS to authorize the 
incidental take caused by the applicant's specified activities, 
provided certain findings are made (Id.). In some cases, foreign 
militaries may participate in U.S. Navy training or testing activities 
in the HSTT Study Area. As stated in the proposed rule, the HMAS Sydney 
most likely struck the two fin whales around 6:25 a.m. the morning of 
May 7, 2021 while the HMAS Sydney was getting into position to 
participate in a U.S. Navy-led exercise later that day but was not 
actively engaged in an exercise at the presumed time of the strike. The 
Navy does not consider the Royal Australian Navy's vessel movements at 
the time of strike as part of the `specified activity' under the MMPA, 
as the strike did not occur while the HMAS Sydney was actively 
participating in a joint training exercise with the U.S. Navy. The MMPA 
is necessarily an applicant-driven process (Melone v. Coit, 100 F.4th 
21, 32 (1st Cir. 2024)) and NMFS has appropriately deferred to the 
Navy's reasoned explanation of why the Royal Australian Navy's 
operations were not part of the ``specified activity.''
    As explained in the Foreign Navies section of this final rule, in 
preparing this rulemaking, NMFS and the U.S. Navy discussed the nature, 
frequency, and control over joint or U.S. Navy-led training and testing 
activities with foreign entities. Consistent with customary 
international law, U.S. Navy requests or encourages participating 
foreign entities to follow U.S. Navy's mitigation measures for that 
particular event, depending on whether the activity is in the U.S.'s 
territorial sea or the EEZ. NMFS and the U.S. Navy also examined the 
Royal Australian Navy 2021 strike report, and NMFS concurred with U.S. 
Navy's conclusion that the strike most likely occurred before, but not 
during, a joint exercise, and the Royal Australian Navy vessel was 
adhering to its standard operating procedures at the time of the 
strike.
    As noted by the commenter in its letter, NMFS assessed the effects 
of foreign military activities. First, the impacts of all activities 
are captured in the baseline for the analysis, through marine mammal 
abundance estimates and population trends found in the SARs. Second, 
NMFS considers foreign military activities, including recent strikes, 
qualitatively in its analysis, as described in the Foreign Navies 
section of this final rule. For instance, NMFS and the U.S. Navy 
examined the Royal Australian Navy 2021 strike report for any lessons 
that could inform U.S. Navy strike mitigation.
    This final rule includes a new reporting measure related to foreign 
vessels. The new measure requires that the Navy's annual HSTT reports 
shall include confirmation 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 U.S. Navy's use of sonar and 
explosives, did not cause exceedance of the analyzed levels (within 
each 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. 
This new reporting measure will allow NMFS to ensure that its analysis 
remains valid.
    Comment 8: A commenter stated that it supports the Navy's request 
for two additional incidental takes of large whales by vessel strike. 
The commenter discussed a U.S. Supreme Court case, Winter v. NRDC, 
Inc., 555 U.S. 7 (2008), in support of its assertion that preparing for 
war still plainly outweighs the interests in the safety of marine life. 
Considering these interests, the commenter recommended that NMFS 
consider granting the Navy's request for two additional incidental 
takes.
    Response: NMFS has made the required findings on the Navy's request 
consistent with the statutory criteria under the MMPA and has 
authorized two additional takes of large whales by serious injury or 
mortality by vessel strike for the remainder of the current regulatory 
period (two takes in addition to the three takes authorized in the 
current regulations). NMFS does not weigh the necessity of Navy 
training and testing against the risks to marine mammals as part of the 
required analysis for issuance of take regulations under the MMPA. The 
MMPA requires NMFS to authorize the incidental take of marine mammals 
caused by specified activities upon request, provided certain findings 
are made (16 U.S.C. 1371(a)(5)(A)). NMFS' least practicable adverse 
impact determination for military readiness activities must include 
consideration of personnel safety, practicality of implementation, and 
impact on the effectiveness of the military readiness activity (16 
U.S.C. 1371(a)(5)(a)(iii)).
    Comment 9: A commenter noted NMFS' reference to Cure et al. (2021) 
and Isojunno et al. (2020) in the 2023 HSTT proposed rule (88 FR 68290, 
October 3, 2023) discussing sperm whale behavioral responses to 
exposure to pulsed active sonar (PAS) and continuous active sonar 
(CAS). The commenter stated that physical trauma, sensory impairment 
(PTS, TTS, and acoustic masking), physiological responses (particularly 
stress responses), and behavioral disturbances are all part of the 
harassment of the whales and that these factors have not been included 
in the ``take'' of the three whales already, only the mortalities have 
been counted. The commenter stated that even brief and transient 
exposure to modest levels of mid-frequency military sonar has been 
observed to cause whales to strand or perish at sea within hours (Dave, 
D.M., & Dave, M., 2023). These studies do not include the permanent 
injuries to these marine mammals' hearing and sonar capabilities. The 
commenter stated that effects on marine mammal hearing are not 
mentioned outside of some studies on stranding and should include more 
study and data collection by marine mammal experts when it comes to PTS 
and sonar damage to these animals due to the impact of the U.S. Navy's 
military ocean noise pollution.
    Response: In the 2023 HSTT proposed rule (88 FR 68290, October 3, 
2023), NMFS included a discussion of relevant literature that had 
published since publication of the 2020 HSTT final rule (85 FR 41780, 
July 10, 2020), and in this final rule, NMFS has included a discussion 
of relevant literature that has published since publication of the 2023 
HSTT proposed rule. Herein, and in the 2023 HSTT proposed rule, NMFS 
discussed all relevant literature, not just that related to vessel 
strike. (See the New Pertinent Science Since Publication of the 2020 
HSTT Final Rule section of the 2023 HSTT proposed rule and the 
Potential Effects of Specified Activities on Marine Mammals and their 
Habitat section of this final rule.)

[[Page 4953]]

    The commenter's statement that ``even brief and transient exposure 
to modest levels of mid-frequency military sonar has been observed to 
cause whales to strand or perish at sea within hours'' is not 
supported. The proposed rule discussed the limited examples of when 
tactical active sonar, in certain circumstances, have been found to 
have likely contributed to marine mammal stranding events. The 
reference that the commenter cites (Dave, D.M. & Dave, M., 2023) states 
that ``even a brief and transient exposure to modest levels of mid-
frequency military sonar has been observed to cause whales to strand or 
perish at sea within hours,'' citing Fern[aacute]ndez et al. (2005) and 
NOAA and U.S. Department of the Navy (2001). These publications discuss 
two specific stranding events in the Canary Islands and the Bahamas, 
respectively. NMFS is aware of stranding events coincident with 
military MFAS use in which exposure to sonar is believed to have been a 
contributing factor and discussed these cases in detail in the 2018 
HSTT proposed rule. While NMFS did not repeat this information in the 
2023 proposed rule as the analyses remain unchanged, NMFS stated in the 
rule that we refer the reader to complete analyses described in the 
2018 HSTT final rule or an updated analysis in the 2020 HSTT final 
rule, where appropriate.
    It is unclear what the commenter means by physical trauma, sensory 
impairment (PTS, TTS, and acoustic masking), physiological responses 
(particularly stress responses), and behavioral disturbances not having 
been included in the ``take'' of the three whales already, and that 
only the mortalities have been counted. In the 2020 HSTT final rule, 
NMFS discussed all of the likely impacts to marine mammals, including 
PTS, TTS, masking, and stress, and authorized take of marine mammals by 
Level B harassment, Level A harassment, and mortality. The 2023 HSTT 
proposed rule and this final rule only discuss changes to NMFS' 
analysis regarding mortality of marine mammals in detail, and refer 
back to the 2018 HSTT proposed and final rules and the 2020 HSTT final 
rule regarding take by Level A harassment and Level B harassment. 
However, NMFS' analysis, including its negligible impact determination, 
takes into consideration the total authorized take, not just mortality.
    Comment 10: A commenter stated that in addition to blue, humpback, 
and fin whales, the Navy also identifies other large whales in its 
request (Bryde's whales, gray whales, minke whales, sperm whales, and 
sei whales) which are also all vulnerable to vessel strikes (Laist et 
al. 2001, Glass et al. 2008, and van der Hoop et al. 2015). NMFS' 2023 
HSTT proposed rule (88 FR 68290, October 3, 2023) determined that the 
likelihood of vessel strikes to those whales is ``discountable'' due to 
their relatively low occurrence in the HSTT Study Area and the fact 
that they have rarely, if ever, been recorded struck by vessels. Due to 
the fact that reported collisions vastly underestimate actual strikes, 
the commenter asks NMFS and the Navy to approach vessel strikes and 
other harm very conservatively, particularly in light of how some of 
these whales are particularly vulnerable to vessel strike and at 
already-small population levels, as detailed in the commenter's July 1, 
2022 letter.
    Response: NMFS concurs with the commenter that all large whales are 
vulnerable to vessel strike, and that reported vessel strikes vastly 
underestimate actual strikes across many industries generally. However, 
NMFS has already conducted a conservative vessel strike analysis. While 
all large whales are vulnerable to vessel strike, it would be 
inappropriate to assume that all large whales that occur in the HSTT 
Study Area are likely to be struck by U.S. Navy vessels.
    Of note, the commenter is correct that NMFS does not anticipate 
vessel strike of Bryde's whale, minke whale, or sperm whale. However, 
NMFS did propose to authorize take by M/SI by vessel strike of sei 
whale and Eastern North Pacific gray whale in the 2023 HSTT proposed 
rule (88 FR 68290, October 3, 2023) and would authorize such take in 
this final rule. NMFS proposed authorizing one take (0.14 takes 
annually) of sei whale (Eastern North Pacific stock) and four takes 
(0.57 takes annually) of Eastern North Pacific gray whale.
    Regarding stocks for which take by M/SI by vessel strike was not 
proposed, as stated in the proposed rule, stocks that have no record of 
ever having been struck by any vessel are considered to have a zero 
percent likelihood of being struck by the Navy in the 7-year period of 
the rule. This includes Bryde's whale, minke whale, and the CA/OR/WA 
stock of sperm whale raised by the commenter (an individual of the 
Hawaii stock of sperm whale was struck in 2007; see table 7 of this 
final rule). Stocks that have never been struck by the Navy, have 
rarely been struck by other vessels, and have a low percent likelihood 
based on the historical vessel strike calculation are also considered 
to have a zero percent likelihood to be struck by the Navy during the 
7-year rule. We note that while vessel strike records have not 
differentiated between Eastern North Pacific and Western North Pacific 
gray whales, given their small population size and the comparative 
rarity with which individuals from the Western North Pacific stock are 
detected off the U.S. West Coast, it is highly unlikely that they would 
be encountered, much less struck. Further, it is unlikely that the 
Hawaii stock of sperm whale would be struck given the zero percent 
likelihood of striking a sperm whale as indicated by the quantitative 
analysis in the Estimated Take From Vessel Strikes and Explosives by 
Serious Injury or Mortality Vessel Strike section of the proposed rule 
and the Authorized Take From Vessel Strikes and Explosives by Serious 
Injury or Mortality section in this final rule. Vessel strikes of the 
Hawaii stock of sperm whale are also unlikely given the fact that the 
last U.S. Navy strike of a Hawaii stock sperm whale was in 2007, before 
the mitigation updates discussed above, and that, with the exception of 
humpback whales, vessel strikes (both military and non-military) of 
other large whale species in the HRC are extremely rare events 
(Carretta 2021b; Carretta 2022). Given this analysis, NMFS concludes 
that the proposed take by M/SI by vessel strike included in the 
proposed rule remains appropriately conservative, and has not included 
take by M/SI by vessel strike of Bryde's whale, Western North Pacific 
gray whale, minke whale, or sperm whale in this final rule.
    Comment 11: A commenter stated that aside from excluding impacts 
from foreign vessels, the proposed rule looks at the impacts of vessel 
strikes on large whales almost in isolation and does not adequately 
assess new science on the combined impacts of the Navy's activities, in 
particular on large whales. The commenter asserted that while the Navy 
acknowledges that sonar and aircraft may affect whales, it does not 
adequately consider the extent of these impacts. Any analysis of the 
impacts of the Navy's exercises must include, in addition to vessel 
strike impacts, the impacts from sonar activities of domestic vessels 
and foreign vessels involved in joint training exercises and any other 
stressor caused by the Navy's activities. The commenter also asserted 
that the Navy's literature review does not adequately focus on the 
large baleen whales that are of concern in this most recent request.
    The commenter stated that as it noted in its July 2022 letter, in 
its review of sound effects on animals, the Navy focuses heavily on 
pinnipeds (seals and sea lions) and odontocetes (dolphins and toothed 
whales), while their request for increased take focuses on mysticetes

[[Page 4954]]

(baleen whales). Mysticetes' hearing systems are different from those 
of pinnipeds and odontocetes, and so while they are closely related one 
cannot infer that each group will experience the same effects from 
sound pollution (Southall et al. 2019). Mysticetes' cochlea have their 
own unique shape, which in concert with the larger mass of baleen 
whales indicates that they are more sensitive to low-frequency sound 
(Southall et al. 2019). Though auditory capabilities in baleen whales 
are understudied (Southall et al. 2019), absence of literature on 
baleen whales does not indicate absence of effect. The commenter stated 
that furthermore, the Navy ignored key papers studying the effect of 
sonar on baleen whales. It specifically stated that the Navy failed to 
consider, and NMFS failed to address in its proposed rule, Goldbogen et 
al. (2013), and further references Southall et al. (2019) and Southall 
et al. (2021).
    Response: NMFS disagrees with the commenter that the proposed rule 
looks at the impacts of vessel strikes on large whales almost in 
isolation and does not adequately assess new science on the combined 
impacts of the Navy's activities, in particular on large whales. While 
NMFS did not repeat discussion of a portion of the analysis that did 
not change (e.g., takes by harassment), this analysis was incorporated 
into the proposed rule and this final rule by reference, and NMFS 
considered those impacts in conjunction with the updated M/SI analysis 
in making its determinations.
    NMFS further disagrees that the literature review should have 
focused on large baleen whales. In the proposed rule (88 FR 68290, 
October 3, 2023), and in this final rule, NMFS' literature review 
discussed recent literature concerning potential impacts from all of 
the Navy's activities, not just those related to vessel strike. As the 
commenter has noted in its letter, NMFS must consider the full range of 
effects of the Navy's activity, not just the potential for vessel 
strike of large whales in isolation. NMFS agrees with the commenter 
that an absence of literature on baleen whales does not indicate an 
absence of effects, nor has NMFS drawn such a conclusion. Rather, NMFS 
conducted a thorough analysis on the impacts of the Navy's activities, 
including sonar and explosive use, on mysticetes, as well as other 
taxa, as described in the proposed rule and this final rule, which in 
some cases, reference the 2018 (83 FR 66846, December 27, 2018) and 
2020 HSTT final rules (85 FR 41780, July 10, 2020). Regarding the 
specific studies that the commenter asserts NMFS failed to consider, 
while not directly cited to in the 2023 HSTT proposed rule (88 FR 
68290, October 3, 2023), NMFS considered and cited Goldbogen et al. 
(2013) in the 2018 (83 FR 66846, December 27, 2018) and 2020 HSTT final 
rules (85 FR 41780, July 10, 2020), and the Navy considered and cited 
this paper in the 2018 HSTT EIS/OEIS. NMFS considered and cited 
Southall et al. (2019) and Southall et al. (2021) in the 2023 HSTT 
proposed rule.
    Please see NMFS' response to Comment 7 regarding foreign vessels.
    Comment 12: A commenter stated that the rule overlooks the 
likelihood that the Navy's activities will take humpback whales from 
the endangered Central America distinct population segment (DPS). The 
commenter stated that its read of the science is that most of the 
humpback whale deaths that occur off California could be from the 
endangered Central America DPS. The commenter further stated that Wade 
et al. (2017) predicted a 67.2 percent movement probability for a whale 
in California to move to Central America. In other words, an estimated 
7.056 Central America DPS humpback whales could die from vessel strikes 
off California annually (10.5 deaths * 0.672). The commenter stated in 
its letter that applying the Rockwood et al. (2021) model, 10.5 
humpback mortalities occur annually off California from the January to 
April and July to November periods combined. The commenter stated that 
this does not include potential deaths from other sources or in other 
locations yet still represents a significant source of mortality for 
this already endangered population.
    Response: NMFS carefully considered the potential for each stock of 
large whales to be taken by serious injury or mortality by vessel 
strike. As stated in the 2023 HSTT proposed rule (88 FR 68290, October 
3, 2023), regarding the likelihood of striking a humpback whale from a 
particular DPS, NMFS evaluated the relative abundance of each of these 
DPS in California waters. Curtis et al. (2022) estimated the abundance 
of the Central America DPS to be 1,496 whales. From Wade et al. (2017), 
about 93 percent (or 1,391 whales) of these humpbacks that winter in 
Central America will move to Oregon/California in the summer months. 
While there is currently no abundance estimate for the Mexico DPS, an 
estimated 3,477 whales from the Mexico DPS feed off the U.S. West Coast 
(Calambokidis and Barlow 2020; Curtis 2022). Based on this information, 
we estimate that approximately 30 percent of the humpback whales off 
the coast of California may be from the Central America DPS and the 
remaining 70 percent are expected to be from the Mexico DPS. Therefore, 
we anticipate that if a Navy vessel strike of a humpback whale were to 
occur within SOCAL, it would likely be from the Mexico DPS.
    The commenter is correct that Wade et al. (2017) predicts that 67.2 
percent of whales that summer in Oregon and California will move to 
Central America for the winter. However, NMFS disagrees with the 
commenter's implication that it is more appropriate for NMFS to assume 
that 67.2 percent of humpbacks off of California are of the Central 
America DPS, and the commenter has not provided justification for doing 
so. (Of note, an updated paper from Wade (2021) shows that 58 percent 
of whales that summer in Oregon and California will move to Mexico 
(only 42 percent will move to Central America)). Rather, NMFS continues 
to find that it is appropriate to use the abundance estimates described 
above and the estimate that approximately 93 percent of humpbacks that 
winter in Central America will move to Oregon/California in the summer 
months to determine the relative abundance of each DPS off the coast of 
California. Therefore, NMFS continues to conclude that if a Navy vessel 
strike of a humpback whale were to occur within SOCAL, it would likely 
be from the Mexico DPS.

Mitigation and Monitoring

    Comment 13: A commenter stated that in addition to strengthening 
the new and revised mitigation measures that NMFS included in the 2023 
HSTT proposed rule, it should also require the following additional 
mitigation measures to ensure the least practicable adverse impact to 
marine mammals. The commenter noted that it and others have requested 
and expounded upon these measures in previous comment letters.
    1. Reinstating more protective mitigation areas and restricted 
training exercises in key migration corridors, feeding habitat, and 
other biologically important areas (BIAs) and creating/expanding 
protective mitigation areas to protect newly recognized critical 
habitat and other BIAs. In a related comment, a separate commenter 
stated that the chances of an incidental take can be dramatically 
reduced by adjusting the time and location of exercises (e.g., 
minimizing activity in the vicinity of California's Channel Islands 
during July-October) and reducing speed in mitigation areas. The 
commenter further asserted that additional BIAs identified by Kratofil 
et al. 2023 provide new

[[Page 4955]]

information that necessitates reevaluation of mitigation measures, yet 
NMFS rejects adding these new mitigation areas as ``impracticable.'' A 
third commenter stated that it is crucial to integrate scientific 
research, public awareness, and proactive measures to ensure the 
sustained well-being of gray whales and the preservation of their 
migratory habitats.
    2. Restricting activities when whale detection is particularly 
difficult, such as periods of low visibility (Williams et al. 2016).
    3. Improving detection of marine mammals by adding alternative 
detection methods, including safe/environmentally-sound drone, thermal, 
and/or acoustic technologies, to lookouts/observers (Verfuss et al. 
2018). In a related comment, a commenter recommended utilizing existing 
acoustic detection systems to track marine mammals in near real-time.
    4. Capping/reducing the level of naval activities authorized each 
year, in particular major exercises. In a related comment, a separate 
commenter stated that it is crucial to limit the [Navy]'s takes on 
marine mammals.
    5. Halting training exercises when whale presence in the area is 
``High'' or ``Very High,'' per WhaleSafe (see https://whalesafe.com).
    Response: Under the MMPA, NMFS' least practicable adverse impact 
determination for military readiness activities must include 
consideration of personnel safety, practicality of implementation, and 
impact on the effectiveness of the military readiness activity (16 
U.S.C. 1371(a)(5)(a)(iii)). NMFS has responded to these recommended 
measures, by corresponding number.
    1. In the 2023 HSTT proposed rule, NMFS discussed that since 
publication of the 2020 HSTT final rule, Kratofil et al. (2023) 
identified updated BIAs in Hawaii. The HSTT Study Area overlaps the 
updated BIAs for small and resident populations of the following 
species in Hawaii: spinner dolphin, short-finned pilot whale, rough-
toothed dolphin, pygmy killer whale, pantropical spotted dolphin, 
melon-headed whale, false killer whale, dwarf sperm whale, goose-beaked 
whale, common bottlenose dolphin, and Blainville's beaked whale. 
Further, the HSTT Study Area overlaps updated BIAs for humpback whale 
reproduction in Hawaii. The updated BIAs overlap critical Navy training 
and testing areas within the HSTT Study Area, including most of the 
internal Navy operating areas. Please see Kratofil et al. (2023) for 
additional details about the BIAs.
    Since publication of the 2023 HSTT proposed rule, Calambokidis et 
al. (2024) identified updated BIAs on the West Coast of the U.S. The 
HSTT Study Area overlaps feeding BIAs for blue whale and fin whale in 
SOCAL. Additionally, it overlaps a reproductive BIA as well as 
northbound and southbound migratory BIAs for gray whale. Please see 
Calambokidis et al. (2024) for additional details about the BIAs.
    NMFS and the Navy considered additional mitigation areas (beyond 
those already identified with associated measures to reduce impacts to 
marine mammals) to further protect marine mammals, including 
odontocetes with small or resident populations in the HSTT Study Area, 
and large whales with feeding, reproductive, and migratory BIAs in the 
HSTT Study Area. This includes consideration of new mitigation areas 
that could be based on newly identified BIAs in Hawaii (Kratofil et al. 
2023) and on the West Coast (Calambokidis et al. 2024). The HRC 
overlaps BIAs identified in Kratofil et al. (2023) for humpback whale, 
spinner dolphin, short-finned pilot whale, rough-toothed dolphin, pygmy 
killer whale, pantropical spotted dolphin, melon-headed whale, false 
killer whale, dwarf sperm whale, goose-beaked whale, common bottlenose 
dolphin, and Blainville's beaked whale. All of the BIAs that overlap 
the HRC are small and resident population BIAs, with the exception of 
the humpback whale reproductive BIA. SOCAL overlaps BIAs identified in 
Calambokidis et al. (2024) for blue whale (feeding area), fin whale 
(feeding area), and gray whale (migratory route).
    Additional restrictions in mitigation areas beyond those 
restrictions and areas included in the 2020 HSTT final rule (including 
mitigation to reduce vessel strike risk such as vessel speed 
restrictions, and in consideration of the newly identified BIAs 
(Kratofil et al. 2023 and Calambokidis et al. 2024)) is impracticable 
given overlap with critical Navy training areas in the HRC and SOCAL, 
including areas around the Channel Islands in SOCAL. However, many of 
the BIAs identified in Kratofil et al. 2023 and Calambokidis et al. 
(2024) partially or fully overlap the mitigation areas included in the 
2020 HSTT final rule and this final rule and are aimed at reducing 
impacts to the same species for which Kratofil et al. 2023 and 
Calambokidis et al. (2024) identified BIAs. In the HRC, the existing 
mitigation areas are targeted and expected to reduce impacts to 
humpback whales, false killer whales, dwarf sperm whales, pygmy killer 
whales, short-finned pilot whales, melon-headed whales, bottlenose 
dolphins, spotted dolphins, spinner dolphins, rough-toothed dolphins, 
goose-beaked whales, and Blainville's beaked whales (i.e., all species 
for which Kratofil et al. (2023) identified BIAs). In SOCAL, the 
existing mitigation areas are aimed at reducing impacts to blue whales, 
fin whales, and gray whales (i.e., all species for which Calambokidis 
et al. (2024) identified BIAs). Further, as included in the 2023 HSTT 
proposed rule, this final rule requires that Navy personnel must issue 
real-time notifications to Navy vessels of large whale aggregations 
(four or more whales) within 1 nmi (1.9 km) of a Navy vessel in a 
select area of SOCAL, and that Navy personnel must send alerts to Navy 
vessels of increased risk of strike following any reported Navy vessel 
strike in the HSTT Study Area. Last, this final rule includes 
modification of two mitigation measures from the 2020 HSTT final rule 
(85 FR 41780; July 10, 2020) to further reduce the potential for vessel 
strike.
    Beyond the papers described herein, NMFS is not aware of, nor have 
commenters provided, additional research that suggests other areas 
warrant additional mitigation. While NMFS agrees with the commenter 
that public awareness can be an important part of gray whale 
conservation, NMFS does not anticipate that additional public awareness 
would assist in mitigating effects of Navy's activities on gray whales, 
and therefore, has not required the Navy to implement measures related 
to public awareness. For a discussion of the mitigation measures 
required by this final rule, please see the Mitigation Measures 
section.
    Please see NMFS' response to Comment 14 regarding vessel speed 
restrictions.
    2. Anti-submarine warfare training involving the use of mid-
frequency active sonar (MFAS) typically involves the periodic use of 
active sonar to develop the ``tactical picture,'' or an understanding 
of the battle space (e.g., area searched or unsearched, presence of 
false contacts, and an understanding of the water conditions). 
Developing the tactical picture can take several hours or days, and 
typically occurs over vast waters with varying environmental and 
oceanographic conditions. Training during both high visibility (e.g., 
daylight, favorable weather conditions) and low visibility (e.g., 
nighttime, inclement weather conditions) is vital because sonar 
operators must be able to understand the environmental differences 
between day and night and

[[Page 4956]]

varying weather conditions and how they affect sound propagation and 
the detection capabilities of sonar. Temperature layers move up and 
down in the water column and ambient noise levels can vary 
significantly between night and day, affecting sound propagation and 
how sonar systems are operated. Reducing or securing power in low-
visibility conditions as a mitigation would affect a commander's 
ability to develop the tactical picture and would prevent sonar 
operators from training in realistic conditions. Further, during 
integrated training multiple vessels and aircraft may participate in an 
exercise using different dimensions of warfare simultaneously (e.g., 
submarine warfare, surface warfare, air warfare, etc.). If one of these 
training elements were adversely impacted (e.g., if sonar training 
reflecting military operations were not possible), the training value 
of other integrated elements would also be degraded. Additionally, 
failure to test such systems in realistic military operational 
scenarios increases the likelihood these systems could fail during 
military operations, thus unacceptably placing sailors' lives and the 
Nation's security at risk. Some systems have a nighttime testing 
requirement; therefore, these tests cannot occur only in daylight 
hours. Reducing or securing power in low visibility conditions would 
decrease the Navy's ability to determine whether systems are 
operationally effective, suitable, survivable, and safe for their 
intended use by the fleet even in reduced visibility or difficult 
weather conditions.
    3. The Navy has compiled information related to the effectiveness 
of certain equipment to detect marine mammals in the context of their 
activities, as well as the practicality and effect on mission 
effectiveness of using various equipment. NMFS has reviewed this 
evaluation and concurs with the characterizations and the conclusions 
below.
    Thermal detection--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. 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. 
In one study, a false positive rate approaching one incorrect 
notification per 4 min of observation was noted.
    The Navy has been investigating the use of thermal detection 
systems with automated marine mammal detection algorithms for future 
mitigation during training and testing, including on autonomous 
platforms. Thermal detection technology being researched by the Navy, 
which is largely based on existing foreign military grade hardware, is 
designed to allow observers and eventually automated software to detect 
the difference in temperature between a surfaced marine mammal (i.e., 
the body or blow of a whale) and the environment (i.e., the water and 
air). Although thermal detection may be reliable in some applications 
and environments, the current technologies are limited by their: (1) 
Low sensor resolution and a narrow field of view, (2) reduced 
performance in certain environmental conditions, (3) inability to 
detect certain animal characteristics and behaviors, and (4) high cost 
and uncertain long-term reliability.
    Thermal detection systems for military applications are deployed on 
various Department of Defense (DoD) platforms. These systems were 
initially developed for night time targeting and object detection such 
as a boat, vehicle, or people. 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, not optimized for marine mammal 
detection, 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. One example of trying to use existing DoD thermal systems is 
being proposed by the U.S. Air Force. The Air Force agreed to attempt 
to use specialized U.S. Air Force aircraft with military thermal 
detection systems for marine mammal detection and mitigation during a 
limited at-sea testing event. It should be noted, however, that these 
systems are specifically designed for and integrated into a small 
number of U.S. Air Force aircraft and cannot be added or effectively 
transferred universally to Navy aircraft. The effectiveness remains 
unknown in using a standard DoD thermal system for the detection of 
marine mammals without the addition of customized system-specific 
computer software to provide critical reliability (enhanced detection, 
cueing for an operator, reduced false positive, etc.)
    Finally, current DoD thermal sensors are not always 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 combination of thermal 
technology and automated algorithms are still undergoing demonstration 
and validation under Navy funding.
    Thermal detection systems specifically for marine mammal detection 
have not been sufficiently studied both in terms of their effectiveness 
within the environmental conditions found in the HSTT Study Area and 
their compatibility with Navy training and testing (i.e., polar waters 
vs. temperate waters). The effectiveness of even the most advanced 
thermal detection systems with technological designs specific to marine 
mammal surveys is highly dependent on environmental conditions, animal 
characteristics, and animal behaviors. At this time, thermal detection 
systems have not been proven to be more effective than, or equally 
effective as, traditional techniques currently employed by the Navy to 
observe for marine mammals (i.e., naked-eye scanning, hand-held 
binoculars, high-powered binoculars mounted on a ship deck). Focusing 
on thermal detection systems could also provide a distraction from and 
compromise to the Navy's ability to implement its established 
observation and mitigation requirements. Last, the Navy does not have 
available manpower to add Lookouts to use thermal detection systems in 
tandem with existing Lookouts who are using traditional observation 
techniques.
    The Defense Advanced Research Projects Agency funded six initial 
studies to test and evaluate infrared-based thermal detection 
technologies and algorithms to automatically detect marine mammals on 
an unmanned surface vehicle. Based on the outcome of these initial 
studies, the Navy is pursuing additional follow-on research efforts.

[[Page 4957]]

    The Office of Naval Research Marine Mammals and Biology program 
funded a project (2013-2019) to test the thermal limits of infrared-
based automatic whale detection technology. That project focused on 
capturing whale spouts at two different locations featuring subtropical 
and tropical water temperatures, optimizing detector/classifier 
performance on the collected data, and testing system performance by 
comparing system detections with concurrent visual observations. 
Results indicated that thermal detection systems in subtropical and 
tropical waters can be a valuable addition to marine mammal surveys 
within a certain distance from the observation platform (e.g., during 
seismic surveys, vessel movements), but have challenges associated with 
false positive detections of waves and birds (Boebel, 2017). While 
Zitterbart et al. (2020) reported on the results of land-based thermal 
imaging of passing whales, their conclusion was that thermal technology 
under the right conditions and from land can detect a whale within 3 km 
although there could also be lots of false positives, especially if 
there are birds, boats, and breaking waves at sea.
    The Navy's Living Marine Resources program is funding one ongoing 
thermal imaging project entitled ``Thermal Imaging for Vessel Strike 
Mitigation on Autonomous Vessels Project 68''. The project is focused 
on adapting and testing two thermal imaging-based whale detection 
systems to reduce the potential for vessel strike during navigation of 
unmanned Navy surface vessels. Phase one is planned for 2024 and 2025. 
The schedule for subsequent phases will be determined as work 
progresses. Project details are available at: https://exwc.navfac.navy.mil/Portals/88/Documents/EXWC/Environmental_Security/Living%20Marine%20Resources/LMRFactSheet_Project68.pdf.
    The Navy plans to continue researching thermal detection systems 
for marine mammal detection to determine their effectiveness and 
compatibility with Navy applications. If the technology matures to the 
state where thermal detection is determined to be an effective 
mitigation tool during training and testing, NMFS and the Navy will 
assess the practicability of using the technology during training and 
testing events and retrofitting the Navy's observation platforms with 
thermal detection devices. The assessment will include an evaluation of 
the budget and acquisition process (including costs associated with 
designing, building, installing, maintaining, and manning the 
equipment); logistical and physical considerations for device 
installment, repair, and replacement (e.g., conducting engineering 
studies to ensure there is no electronic or power interference with 
existing shipboard systems); manpower and resource considerations for 
training personnel to effectively operate the equipment; and 
considerations of potential security and classification issues. New 
system integration on Navy assets can entail up to 5 to 10 years of 
effort to account for acquisition, engineering studies, and development 
and execution of systems training. The Navy will provide information to 
NMFS about the status and findings of Navy-funded thermal detection 
studies and any associated practicability assessments at the annual 
adaptive management meetings.
    Passive Acoustic Monitoring--Regarding the recommendation to 
utilize existing acoustic detection systems to track marine mammals in 
near real-time, the Navy does employ passive acoustic monitoring when 
practicable to do so (i.e., when assets that have passive acoustic 
monitoring capabilities are already participating in the activity). For 
other explosive events, there are no platforms participating that have 
passive acoustic monitoring capabilities. Adding a passive acoustic 
monitoring capability (either by adding a passive acoustic monitoring 
device to a platform already participating in the activity, or by 
adding a platform with integrated passive acoustic monitoring 
capabilities to the activity, such as a sonobuoy) for mitigation is not 
practicable. As discussed in chapter 5 (Mitigation), section 5.5.3 
(Active and Passive Acoustic Monitoring Devices) of the 2018 HSTT FEIS/
OEIS, there are significant manpower and logistical constraints that 
make constructing and maintaining additional passive acoustic 
monitoring systems or platforms for each training and testing activity 
impracticable. Additionally, diverting platforms that have passive 
acoustic monitoring platforms would impact their ability to meet their 
Title 10 requirements for maintaining military readiness and reduce the 
service life of those systems.
    The use of real-time PAM for mitigation at the Southern California 
Anti-submarine Warfare Range (SOAR) exceeds the capability of current 
technology. The Navy has a significant research investment in the 
Marine Mammal Monitoring on Navy Ranges (M3R) system at three ocean 
locations including SOAR. However, this system was designed and 
intended to support marine mammal research for select species, and not 
as a mitigation tool. Marine mammal PAM using instrumented hydrophones 
is still under development and while it has produced meaningful results 
for marine species monitoring, abundance estimation, and research, it 
was not developed for, nor is it appropriate for, real-time mitigation. 
The ability to detect, classify, and develop an estimated position (and 
the associated area of uncertainty) differs across species, behavioral 
context, animal location vs. receiver geometry, source level, etc.
    Based on current capabilities, and given adequate time, vocalizing 
animals within an indeterminate radius around a particular hydrophone 
are detected, but obtaining an estimated position for all individual 
animals passing through a predetermined area is not assured. Detecting 
vocalizations on a hydrophone does not determine whether vocalizing 
individuals would be within the established mitigation zone in the 
timeframes required for mitigation. Since detection ranges are 
generally larger than current mitigation zones for many activities, 
this would unnecessarily delay events due to uncertainty in the 
animal's location and put at risk event realism. If an event were to be 
moved based upon low-confidence localizations, it may inadvertently be 
moved to an area where non-vocalizing animals of undetermined species 
are present.
    To develop an estimated position for an individual, it must be 
vocalizing and its vocalizations must be detected on at least three 
hydrophones. The hydrophones must have the required bandwidth, and 
dynamic range to capture the signal. In addition, calls must be 
sufficiently loud so as to provide the required signal to noise ratio 
on the surrounding hydrophones. Typically, small odontocetes echolocate 
with a directed beam that makes detection of the call on multiple 
hydrophones difficult. Developing an estimated position of selected 
species requires the presence of whistles which may or may not be 
produced depending on the behavioral state. Beaked whales at SOAR 
vocalize only during deep foraging dives which occur at a rate of 
approximately 10 per day. They produce highly directed echolocation 
clicks that are difficult to simultaneously detect on multiple 
hydrophones. Current real-time systems cannot follow individuals and at 
best produce sparse positions with multiple false locations. The 
position estimation process must occur in an area with hydrophones 
spaced to allow the detection of the same echolocation click on at 
least three hydrophones. Typically, a spacing of less than 4 km

[[Page 4958]]

in water depths of approximately 2 km is preferred. In the absence of 
detection, the analyst can only determine with confidence if a group of 
beaked whales is somewhere within 6 km of a hydrophone. Beaked whales 
produce stereotypic click trains during deep (500 m) foraging dives. 
The presence of a vocalizing group can be readily detected by an 
analyst by examining the click structure and repetition rate. However, 
estimating position is possible only if the same train of clicks is 
detected on multiple hydrophones which is often precluded by the 
animal's narrow beam pattern. Currently, this is not an automated 
routine.
    In summary, the analytical and technical capabilities required to 
use PAM such as M3R at SOAR as a required mitigation tool are not 
sufficiently robust to rely upon due to limitations with near real-time 
classification and determining estimated positions. The level of 
uncertainty as to a species presence or absence and location are too 
high to provide the accuracy required for real-time mitigation. As 
discussed in chapter 5 (Mitigation) of the 2018 HSTT FEIS/OEIS, 
existing Navy visual mitigation procedures and measures, when performed 
by individual units at-sea, still remain the most effective and 
practical means of protection for marine species.
    NMFS is not requiring drones to be used at this time and the 
commenters did not provide information supporting the recommendation 
that they be used when considering the extensive monitoring by Lookouts 
required.
    4. The commenters neither offer a rationale for why a cap on the 
level of activities is needed nor do they suggest what an appropriate 
cap might be. The Navy is responsible under Title 10 of the U.S. Code 
for conducting the needed amount of testing and training to maintain 
military readiness, which is what they have proposed and NMFS has 
analyzed. Further, the MMPA states that NMFS shall issue MMPA 
authorizations if the necessary findings can be made, as they have been 
here. Importantly, as described in the Mitigation Measures section, the 
Navy has determined that it is practicable to limit activities (active 
sonar, explosive use, etc.) to varying degrees in five areas that are 
important to sensitive species or for important behaviors in order to 
minimize impacts that are more likely to lead to adverse effects on 
rates of recruitment or survival and is required by this final rule to 
do so.
    5. During the promulgation of this rule, NMFS and the Navy fully 
explored the potential for the Navy to incorporate WhaleSafe into its 
mitigation methods. However, the current WhaleSafe operational areas 
(Santa Barbara Channel and off the coast of San Francisco) do not 
overlap the HSTT Study Area. As such, while WhaleSafe can inform whale 
occurrence in other areas of Southern California, it is not an 
appropriate tool for determining mitigation actions in the HSTT Study 
Area, and NMFS has not required the Navy to halt training exercises 
when WhaleSafe indicates that whale presence in the area is ``high'' or 
``very high'' as suggested by the commenter. However, NMFS has 
recommended to the Navy, including as a conservation recommendation in 
the 2024 reinitiated Biological and Conference Opinion, that it explore 
funding options and seek partnership opportunities for the development 
of a mapping and analysis tool that integrates acoustic and visual 
whale detections with model predictions to display near real-time whale 
presence data within the SOCAL and nearby surrounding areas. 
Information generated by such a tool could then be used by Navy, and 
potentially non-military, vessels to reduce the risk of large whale 
vessel strike in Southern California.
    Comment 14: A commenter stated that NMFS must substantially 
strengthen mitigation measures, including requiring more effective 
measures to protect large whales from vessel strikes, before issuing 
any additional take authorizations to the Navy. The commenter stated 
that NMFS rejected other mitigation measures, such as requiring vessels 
used in the Navy's activities to slow to 10 kn (18.5 km per hour) or 
less in certain BIAs to reduce the risk of vessel strikes, by 
downplaying the risk of vessel strikes to endangered whales and other 
species impacted by the Navy's activities. The commenter stated that 
NMFS' proposed modifications to the mitigation measures fall short of 
meeting the least practicable adverse impact standard. Commenters 
provided several specific recommendations for mitigation measures.
    1. The 2023 HSTT proposed rule included a revised mitigation 
measure that states ``if marine mammals are observed, Navy personnel 
must maneuver (which may include reducing speed as the mission or 
circumstances allow) to maintain distance.'' The reference to reducing 
speed as the mission or circumstances allow is a revision from the 
measure in the 2020 HSTT final rule. The commenter stated that this 
measure should be mandatory in important whale habitat, where whales 
are known to occur, and where vessel strikes have occurred or are 
expected to occur, and should be implemented in these areas even when 
whales have not been observed by Lookouts. Another commenter 
recommended focusing on vessel speeds and their impact on marine mammal 
safety to mitigate the risks associated with high-speed vessel travel 
and including revised protocols.
    2. The 2023 HSTT proposed rule also requires that Navy personnel 
must send alerts to Navy vessels of increased risk of strike following 
any reported Navy vessel strike in the HSTT Study Area. The commenter 
stated that NMFS should attach specific actions required of other 
vessels in the area, including a 10 kn (18.5 km per hour) ship speed, 
when a Navy vessel strike has been reported, in order to reduce the 
risk of further strikes. The commenter stated that these alerts should 
also go to non-Navy vessels in the vicinity that pose a risk to whales.
    3. The 2023 HSTT proposed rule modified the requirement for 
awareness messages disseminated in Southern California. The commenter 
stated that it supports the use of more accurate seasonal information 
to inform large whale awareness messages, but expects awareness and 
alerts to be tied to more robust mitigation action, and recommends that 
if a marine mammal is spotted, NMFS should require a mandatory 10 kn 
(18.5 km per hour) ship speed limit.
    4. The 2023 HSTT proposed rule also contains a new mitigation 
measure in which Navy personnel would issue real-time notifications to 
Navy vessels of large whale aggregations (four or more whales) within 1 
nmi (1.9 km) of a Navy vessel in a select area of SOCAL (Of note, the 
four whales do not have to be the same species and do not have to be 
part of the same group (e.g., two whales of one species sighted at a 
distance off the port side at 500 yards (yd; 457.2 m) and two more 
whales of another species sighted off the starboard side at 500 yd 
(457.2 m) would be considered an aggregation under this measure)). The 
commenter recommended that (a) this should apply any time a whale is 
sighted (i.e., Navy should not have to observe at least four whales to 
trigger this measure), (b) this should have no geographic limitation, 
and (c) this should trigger a mandatory 10 kn (18.5 km per hour) ship 
speed limit.
    5. A commenter stated that the Navy will evaluate future revisions 
to online or DVD Marine Species Awareness Training (MSAT) video 
training to emphasize that when a protected species is spotted, this 
may be an indicator that additional marine

[[Page 4959]]

mammals are present and nearby, and the vessel should take this into 
consideration when transiting. The commenter stated that this purported 
mitigation measure should be more forceful; when a protected species is 
spotted, protective actions must result.
    Response: Under the MMPA, NMFS' least practicable adverse impact 
determination for military readiness activities must include 
consideration of personnel safety, practicality of implementation, and 
impact on the effectiveness of the military readiness activity (16 
U.S.C. 1371(a)(5)(a)(iii)). The recommendation for NMFS to require, in 
some cases a reduction in speed, and in other cases a 10 kn (18.5 km 
per hour) speed limit, generally speaking, is impracticable because 
these speed reductions and further reductions to Navy vessel speeds 
negatively impact mission effectiveness. The Navy is unable to impose a 
10 kn (18.5 km per hour) ship speed limit because it would not be 
practical to implement and would impact the effectiveness of Navy's 
activities by putting constraints on training and testing. The Navy 
requires flexibility in the use of variable ship speeds for training, 
testing, operational, safety, and engineering qualification 
requirements. Navy ships typically use the lowest speed practical given 
individual mission needs. NMFS has reviewed the Navy's analysis of 
these additional restrictions and the impacts they would have on 
military readiness and concurs with the Navy's assessment that they are 
impracticable. That said, NMFS has strengthened its mitigation 
requirement requiring Navy personnel to maneuver if marine mammals are 
observed to add ``which may include reducing speed as the mission or 
circumstances allow'' to emphasize that reduction of speeds should be 
considered where appropriate. Of note, current Navy Standard Operating 
Procedures and mitigations require a minimum of at least three Lookouts 
on duty on Navy cruisers and destroyers while underway and, so long as 
safety of navigation is maintained, to keep 500 yards away from large 
whales and 200 yards away from other marine mammals (except for bow-
riding dolphins and pinnipeds hauled out on shore or man-made 
navigational structures, port structures, and vessels).
    Previously, the Navy commissioned a vessel density and speed report 
based on an analysis of Navy ship traffic in the HSTT Study Area 
between 2011 and 2015. Median speed of all Navy vessels within the HSTT 
Study Area is typically already low, with median speeds between 5 and 
12 kn (9.2 to 22.2 km per hour). Further, the presence and transits of 
commercial and recreational vessels, annually numbering in the 
thousands, poses a more significant risk to large whales than the 
presence of Navy vessels. The Vessel Strike subsection of the Estimated 
Take of Marine Mammals section of the 2020 HSTT final rule and this 
rule and the 2018 HSTT FEIS/OEIS chapter 3 (Affected Environment and 
Environmental Consequences) section 3.7.3.4.1 (Impacts from Vessels and 
In-Water Devices) and Appendix K, section K.4.1.6.2 (San Diego (Arc) 
Blue Whale Feeding Area Mitigation Considerations), explain the 
important differences between most Navy vessels and their operation and 
commercial ships that make Navy vessels much less likely to strike a 
whale.
    When developing Phase III mitigation measures, the Navy analyzed 
the potential for implementing additional types of mitigation, such as 
vessel speed restrictions within the HSTT Study Area. The Navy 
determined that based on how the training and testing activities will 
be conducted within the HSTT Study Area, vessel speed restrictions 
would be incompatible with practicability criteria for safety, 
sustainability, and training and testing missions, as described in 
chapter 5 (Mitigation), section 5.3.4.1 (Vessel Movement) of the 2018 
HSTT FEIS/OEIS. NMFS fully reviewed this analysis and concurs with the 
Navy's conclusions. During the promulgation of this final rule, NMFS 
again discussed the potential for vessel speed restrictions, including 
during limited times and areas, and Navy continued to assert that such 
restrictions are not practicable. After thorough discussion, NMFS again 
concurs with the Navy's conclusions.
    Regarding the recommendation for Navy to send alerts of increased 
risk of strike to non-Navy vessels (such as through the WhaleAlert 
app), Navy has informed NMFS that transmitting information between Navy 
and civilian vessels poses security risks that make sending alerts to 
non-Navy vessels impracticable.
    Regarding the recommendations for the measure described in number 4 
to be implemented when a single whale is sighted and in all areas, Navy 
asserts that doing so is not practicable as it would interfere with its 
mission success. Four whales was determined to be the appropriate 
trigger for this measure as it represents an increased strike risk 
without occurring so often that this measure becomes impracticable for 
the Navy to implement. Regarding the geographic limitations, this 
measure would apply to the area between 32-33 degrees North and 117.2-
119.5 degrees West, which includes the locations where recent (2009, 
2021, 2023) strikes occurred, and historic locations where strikes 
occurred when precise latitude and longitude were known. Given that 
this area includes the location where all known strikes have occurred, 
NMFS anticipates that this measure is of particular importance in this 
area, and Navy asserted that implementing this measure more broadly 
would be impracticable, as it could divert the attention of bridge 
personnel from other critical tasks.
    As stated by the commenter, the Navy will evaluate future revisions 
to online or DVD MSAT video training to emphasize that when a protected 
species is spotted, this may be an indicator that additional marine 
mammals are present and nearby, and the vessel should take this into 
consideration when transiting. NMFS does not dictate exactly what 
measure must be taken, as different situations warrant different 
actions and may have different safety and practicability 
considerations.
    The 2023 HSTT proposed rule and this final rule include two new 
mitigation measures beyond that required by the 2020 HSTT final rule 
and modification of two existing mitigation measures. Please see NMFS' 
response to Comment 15.
    With the exception of the recommended mitigation measures discussed 
within this Comments and Responses section, the commenter has not 
demonstrated why NMFS has not met the least practicable adverse impact 
standard. As described in the Mitigation Measures section of this final 
rule, NMFS has included the mitigation requirements necessary to 
achieve the least practicable adverse impact on the affected species or 
stocks and their habitat.
    Comment 15: Multiple commenters stated that, rather than 
authorizing additional take by serious injury or mortality by vessel 
strike, NMFS should require the Navy to implement additional mitigation 
measures to avoid harassment and future vessel strikes of large whales. 
Commenters specifically referenced the 2021 Royal Australian Navy 
vessel strikes of fin whales, with one commenter referencing what it 
describes as NMFS' acknowledgement of the susceptibility of fin whales 
to vessel strike year-round, and another stating that the Royal 
Australian Navy vessel strikes should be factored into the take 
calculation for the HSTT Study Area.
    In a related comment, a commenter questioned whether the Navy can

[[Page 4960]]

continuously keep asking for more takes if they continue to reach their 
authorized number.
    Response: Based on the available information at the time that the 
2020 HSTT final rule was promulgated, NMFS' analysis suggested that 
three takes by serious injury or mortality by vessel strike over the 7-
year duration of the HSTT rule could occur. To date, NMFS is aware of 
three confirmed vessel strikes of large whales by U.S. Navy vessels 
during the current regulatory period. While those three takes are 
within what NMFS anticipated could occur, given that three years 
remained of the effective period of the rule when the first two strikes 
occurred, the Navy reanalyzed the potential for take by mortality and 
serious injury by vessel strike over the duration of the rule, and that 
analysis suggested that additional takes could occur. NMFS' subsequent 
analysis also suggested that two additional takes could occur over the 
remainder of the regulatory period. NMFS requires the Navy to implement 
mitigation measures to reduce the potential for vessel strike; however, 
this mitigation is not quantitatively incorporated into NMFS' analysis, 
and therefore, does not reduce the number of takes that NMFS 
authorizes.
    Regarding mitigation, the 2023 HSTT proposed rule and this final 
rule include two new mitigation measures beyond that required by the 
2020 HSTT final rule and modification of two existing mitigation 
measures. The new measures include:
     Navy personnel must issue real-time notifications to Navy 
vessels of large whale aggregations (four or more whales) within 1 nmi 
(1.9 km) of a Navy vessel in a select area of SOCAL; and
     Navy personnel must send alerts to Navy vessels of 
increased risk of strike following any reported Navy vessel strike in 
the HSTT Study Area.
    Additionally, the 2020 HSTT final rule (85 FR 41780, July 10, 2020) 
requires Navy personnel to issue seasonal awareness notification 
messages to alert ships and aircraft to the possible presence of blue 
whales, humpback whales, gray whales, and fin whales in the seasons 
that they are most likely to occur in the HSTT Study Area. These 
messages assist in maintaining safety of navigation and in avoiding 
interactions with large whales during transits. This final rule 
requires the Navy to re-title the spring blue whale message (released 
in June) to a large whale awareness message inclusive of typical 
spring-summer large whales in southern California (mainly blue, fin, 
and humpback whales), as included in the 2023 HSTT proposed rule. 
Furthermore, rather than tying the message release to a specific month, 
the message would be for a period based on predicted oceanographic 
conditions for a given year.
    For vessel movement, the 2020 HSTT final rule (85 FR 41780, July 
10, 2020) required that ``when underway, Navy personnel must observe 
the mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must maneuver to maintain distance.'' This measure has 
been updated to state that reducing speed may be an appropriate way to 
maneuver, as included in the 2023 HSTT proposed rule. Please see the 
Mitigation Measures section for a full discussion of these new and 
revised measures.
    NMFS anticipates that additional vessel strike of large whales 
could still occur even in consideration of these additional and 
modified mitigation measures (noting that the mitigation measures are 
not quantitatively included in the vessel strike calculation). 
Therefore, NMFS is authorizing two additional takes of large whales by 
serious injury or mortality by vessel strike over the 7-year duration 
of the HSTT rule (two takes in addition to the three takes authorized 
in the current regulations). In the 2023 HSTT proposed rule and this 
final rule, NMFS describes factors that make fin whales particularly 
susceptible to vessel strike by the Navy in southern California (e.g., 
occurrence, Navy vessel strike history in SOCAL, year-round 
occurrence). As such, NMFS analysis suggests that of the five total 
takes by serious injury or mortality by vessel strike of large whales, 
up to four of those takes could be of the CA/OR/WA stock of fin whale. 
Regarding the suggestion that the Royal Australian Navy vessel strike 
of two fin whales should be factored into the take calculation for the 
HSTT Study Area, as explained in the 2023 HSTT proposed rule and in the 
Vessel Strike section of this final rule, according to the U.S. Navy, 
the May 2021 vessel strike of two fin whales by a Royal Australian Navy 
vessel did not occur while that vessel was participating in a U.S. 
Navy-led training exercise, and the strike of those two fin whales is 
not included in the estimated take by vessel strike calculation. 
Instead, NMFS considered the 2021 vessel strike by the Royal Australian 
Navy along with other strike information when determining which species 
could be among the estimated large whales struck.
    Regarding a commenter's concern about whether the Navy can 
continuously keep asking for more takes if they continue to reach their 
authorized number, as stated in the Background section of this final 
rule, an authorization for incidental takings shall be granted if NMFS 
finds that the taking will have a negligible impact on the species or 
stocks and will not have an unmitigable adverse impact on the 
availability of the species or stocks for taking for subsistence uses 
(where relevant) (16 U.S.C. 1371(a)(5)(A)). Further, NMFS must 
prescribe the permissible methods of taking and other means of 
effecting the least practicable adverse impact on the affected species 
or stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance, and on the 
availability of such species or stocks for taking for certain 
subsistence uses (referred to in this rule as ``mitigation measures''); 
and requirements pertaining to the monitoring and reporting of such 
takings (16 U.S.C. 1371(a)(5)(A)). NMFS has made the required findings, 
and therefore, it must issue the requested incidental take 
authorization to the Navy.
    Comment 16: The 2023 HSTT proposed rule (88 FR 68290, October 3, 
2023) states: ``The 2021 NAVDORM requires the use of three Lookouts on 
Navy cruisers and destroyers as compared to the previous requirement of 
one Lookout when a vessel was underway and not engaged in sonar 
training or testing. However, as discussed in the Mitigation Measures 
section below, the Navy informed NMFS that requiring the additional 
Lookouts as mitigation is not practicable because this SOP may change 
in response to manning issues and national security needs.'' A 
commenter stated that NMFS should reject the Navy's explanation for why 
three lookouts on cruisers and destroyers are not practicable. In a 
related comment, a commenter stated that the 2023 HSTT proposed rule 
seeks to reduce the number of lookouts (the simplest and cheapest 
mitigation strategy) from three to one, and recommended increased 
numbers of lookouts as a mitigation measure. This commenter also 
recommended enhancing bridge resource management. A commenter also 
recommended training for Lookouts.
    Response: Neither the 2023 HSTT proposed rule nor this final rule 
propose a reduction in the number of lookouts required on Navy vessels, 
and it is unclear what the commenter means by enhancing bridge resource 
management, though it is important to note that all bridge 
watchstanders including Lookouts take the Navy's Marine Species 
Awareness Training that NMFS has reviewed and approved. The

[[Page 4961]]

commenter did not suggest what additional training Lookouts should 
receive. As a general matter, NMFS' evaluation of least practicable 
adverse impact appropriately relies heavily on input from the applicant 
regarding the practicability of any given measure provided the 
explanation is reasonable and clear. Further, the 2004 NDAA amended the 
MMPA as it relates to military readiness activities and the incidental 
take authorization process such that a determination of ``least 
practicable adverse impact'' shall include consideration of personnel 
safety, practicality of implementation, and impact on the effectiveness 
of the military readiness activity and consultation with the Department 
of Defense on these considerations (see 16 U.S.C. 1371(a)(5)(A)(iii)). 
The Navy has clearly indicated the need for flexibility to effectively 
carry out foreseeable military readiness activities, such that 
requiring additional Lookouts at all times would be impracticable, and 
we concur with that assessment.
    Comment 17: A commenter stated that if the Navy is allowed a 
greater number of incidental takes on marine life, it must enforce 
strategies to avoid such incidents and suggested that the Navy expand 
its existing precautions to protect marine life and minimize takes of 
marine animals. The commenter encourages the Navy to (1) continue 
implementing state-of-the-art technology and best practices to reduce 
underwater noise and disturbance during training exercises, 
particularly in areas where marine mammals are known to inhabit, (2) 
collaborate with marine biologists and conservation experts to 
continually monitor the effects of Navy activities on marine life and 
suggest corrective actions when necessary, (3) consider adjusting the 
timing or location of training exercises to minimize their impact on 
critical marine habitats and migration paths, and (4) promote 
transparency and cooperation by engaging with environmental 
organizations and local communities to develop and assess mitigation 
strategies collaboratively. In a related comment, another commenter 
stated that advanced technologies should allow the United States 
military to maintain readiness standards and protect wildlife.
    Response: NMFS worked closely with the Navy to investigate the 
recent vessel strikes and to identify ways to improve mitigation 
measures. This final rule includes revision to two existing mitigation 
measures and two new mitigation measures beyond that included in the 
2020 HSTT final rule (85 FR 41780, July 10, 2020; described further in 
response to Comment 15). Of note, this final rule authorizes additional 
take by serious injury or mortality by vessel strike beyond that 
authorized by the 2020 HSTT final rule. This final rule does not 
authorize additional take by Level A or Level B harassment. However, as 
discussed in the Mitigation Measures section of this final rule, 
elsewhere in this section, and in chapter 5 (Mitigation) of the 2018 
HSTT FSEIS/OEIS, the Navy will implement extensive mitigation, both 
procedural mitigation and mitigation areas, to avoid or reduce 
potential impacts from the HSTT activities on marine mammals, including 
impacts from sonar and explosives. (Note that additional measures and 
revisions to some existing measures have been made since publication of 
this FEIS/OEIS). Specifically, the Navy would use a combination of 
delayed starts, powerdowns, and shutdowns to minimize the likelihood of 
M/SI, minimize the likelihood or severity of PTS or other injury, and 
reduce instances of TTS or more severe behavioral disruption caused by 
acoustic sources or explosives. The Navy will limit activities (active 
sonar, explosive use, major training exercises (MTEs), etc.) to varying 
degrees in multiple areas that are important to sensitive species or 
for critical behaviors in order to minimize impacts that are more 
likely to lead to adverse effects on rates of recruitment or survival. 
The mitigation measures would reduce the probability and/or severity of 
impacts expected to result from acute exposure to acoustic sources or 
explosives, vessel strike, and impacts to marine mammal habitat. Please 
see the Mitigation Measures section of this final rule for additional 
detail regarding required mitigation measures.
    Regarding best practices to reduce underwater noise, most of the 
Navy's vessels already have state of the art quieting technologies 
employed to reduce their sound profile to assist them in avoiding 
detection by enemy forces, therefore, they are much quieter than 
commercial/recreational vessels of similar sizes.
    Regarding monitoring the effects of Navy activities on marine life 
and the commenter's recommendation to take corrective actions when 
necessary, as required by this final rule, the Navy implements a robust 
monitoring program. Although the Navy has been conducting research and 
monitoring in the HSTT Study Area for over 20 years, it developed a 
formal marine species monitoring program in support of the MMPA and ESA 
authorizations for the Hawaii and Southern California range complexes 
in 2009. This robust program has resulted in hundreds of technical 
reports and publications on marine mammals that have informed Navy and 
NMFS analyses in environmental planning documents, rules, and 
Biological Opinions. The reports are made available to the public on 
the Navy's marine species monitoring website 
(www.navymarinespeciesmonitoring.us) and the data on the Ocean 
Biogeographic Information System Spatial Ecological Analysis of 
Megavertebrate Populations (OBIS-SEAMAP) (www.seamap.env.duke.edu). For 
additional information about the Navy's monitoring program, please see 
the Monitoring section herein and the websites listed above.
    Further, the regulations governing the take of marine mammals 
incidental to Navy training activities in the HSTT Study Area contain 
an adaptive management component. Our understanding of the effects of 
Navy training and testing activities (e.g., acoustic and explosive 
stressors) on marine mammals continues to evolve, which makes the 
inclusion of an adaptive management component both valuable and 
necessary within the context of 7-year regulations. Please see the 
Adaptive Management section of this final rule for additional 
information.
    Regarding transparency and cooperation, the MMPA does not require 
an independent review of mitigation measures. It does require notice 
and opportunity for public comment (16 U.S.C. 1371(a)(5)(A)(i)). The 
public comment period is a means by which the public (e.g., 
environmental organizations and local communities) are able to provide 
NMFS with mitigation measure recommendations supported by scientific 
evidence that NMFS takes into consideration when finalizing the 
rulemaking.
    Comment 18: A commenter stated that measures should be taken to 
cease any more actions potentially impacting marine mammals. The 2023 
HSTT proposed rule (88 FR 68290, October 3, 2023) states that results 
of a study indicated that Navy Lookout Teams, which include lookouts 
and other crew members, have approximately an 80 percent chance of 
failing to detect a pod of large whales beyond 200 yd (182.9 m), 
compared with a 49 percent chance for trained marine mammal observers. 
The commenter recommended that the Navy hire trained marine mammal 
observers to keep the incidents of whale take to the original take 
numbers or less, and not need to have modifications to the LOA for 
additional animal take. The

[[Page 4962]]

commenter also recommended having experts that can accurately assess 
the physical and mental health of these animals. In a related comment, 
a commenter stated that the rule calls into question whether the three 
vessel strikes that have occurred were due to the crew not spotting the 
whales, not spotting them before the strike, or the Navy not 
emphasizing the importance of spotting and avoiding marine wildlife to 
its personnel.
    Response: As described in the 2023 HSTT proposed rule (88 FR 68290, 
October 3, 2023), a recent study by Oedekoven and Thomas (2022) was 
designed to evaluate the effectiveness of Navy Lookouts at detecting 
marine mammals before they entered a defined set of mitigation zones 
(i.e., 200, 500, and 1,000 yd (182.9, 457.2, and 914.4 m)) during MFAS 
training activities. This study also compared Lookout effectiveness 
with that of trained marine mammal observers. Lookout teams were 
comprised of varying numbers of Lookouts depending on the type of ship 
and the training activity that was occurring (noting that the data was 
collected prior to the Navy's change in its SOPs to require the use of 
three Lookouts on Navy cruisers and destroyers). Marine mammal observer 
teams consisted of two dedicated observers. As noted by the commenter, 
results of this study indicate that Navy Lookout Teams, which include 
Lookouts and other crew members, have approximately an 80 percent 
chance of failing to detect a pod of large baleen whales (rorquals) 
before they come closer than a mitigation range of 200 yd (182.9 m), 
compared with a 49 percent chance for trained marine mammal observers. 
The probability of a pod remaining undetected by Lookouts was greater 
for larger mitigation zones (i.e., 85 percent at 500 yd (457.2 m); 91 
percent at 1,000 yd (914.4 m)). These values require some level of 
interpretation with regard to the numerical results. For instance, the 
study's statistical model assumed that Navy ships moved in a straight 
line at a set speed for the duration of the field trials, and that 
animals could not move in a direction perpendicular to a ship. 
Violation of this model assumption would underestimate Lookout 
effectiveness for some data points. The values for both Navy Lookouts 
and the Marine Mammal Observers include animals under the water that 
would not have been available for detection by a Lookout. This study 
suggests that detection of marine mammals is less certain than 
previously assumed at certain distances. While this study suggests that 
trained marine mammal observers are more effective than Navy Lookouts, 
the Navy has asserted that it is impracticable to station independent 
marine mammal observers on Navy vessels. When making the least 
practicable adverse impact determination for military readiness 
activities, NMFS must consider personnel safety, practicality of 
implementation, and impact on the effectiveness of the military 
readiness activities and must consult with the Department of Defense on 
these considerations (16 U.S.C. 1371(a)(5)(A)(iii)). As described in 
section 5.5.5 (Third-Party Observers) of the 2018 HSTT FEIS/OEIS, use 
of third-party observers on Navy vessels or aircraft would result in 
safety and security clearance issues, berthing shortages or exceedance 
of other space limitations, impacts to Lookouts' abilities to complete 
their other mission-essential duties, and unsustainable costs, among 
other issues. Please see the 2018 HSTT FEIS/OEIS for additional detail.
    Lookouts remain an important component of the Navy's 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, NMFS and the Navy are also 
considering, through the adaptive management process, whether there are 
additional measures that would be practicable to implement that would 
improve effectiveness of Lookouts, such as enhanced personnel training.
    As described in the 2023 HSTT proposed rule (88 FR 68290, October 
3, 2023), the 2021 U.S. Navy vessel strikes were the first known U.S. 
Navy vessel strikes in the HSTT Study Area since 2009. Historically, 
military vessel strikes of large whales within the HSTT Study Area have 
been rare events with only seven such strikes occurring over the past 
14 years, five U.S. Navy strikes, and two Royal Australian Navy 
strikes. Based on the Navy and NMFS' investigation of these recent 
strike incidents, NMFS found that the Navy was substantially following 
the required mitigation protocols, consistent with 16 U.S.C. 
1371(a)(5)(B). These recent vessel strike reports (2021, 2023) appear 
to reflect the sporadic, episodic, or clustered nature of vessel strike 
or may reflect a trend of increased large whale presence in this area 
in the early summer months. Given the size of Navy vessels and the need 
to maintain specific speeds during certain activities, even if a whale 
is detected, a U.S. Navy vessel may not be able to avoid a strike. 
Therefore, given the potential shift in factors contributing to vessel 
strike, and the challenges in avoiding potential strikes, it is 
important to ensure that the compliance process addresses the 
appropriate number of potential strikes and that they are considered in 
the negligible impact determination, which is why it was necessary to 
evaluate the authorization of an additional two takes by strike. The 
MMPA provides for the authorization of incidental take caused by 
specified activities, provided certain findings are made. The law 
directs NMFS to process adequate and complete applications for 
incidental take authorization, and issue the authorization provided all 
statutory findings and requirements, as well as all associated legal 
requirements, are met.
    It is unclear how having experts that can accurately assess the 
physical and mental health of these animals, as suggested by the 
commenter, would assist in mitigating the effects of the Navy's 
activities, nor has the commenter provided detail explaining how. The 
required procedural mitigation measures are implemented within defined 
ranges based on established criteria, and implementation does not rely 
on a visual assessment of behavioral or physiological effects to 
animals. In its analysis, NMFS does consider the potential impacts of 
stress on marine mammals from exposure to the Navy's activities. Please 
see the Stress Response section of the 2018 HSTT Proposed Rule for a 
discussion of stress responses in marine mammals. Further, since that 
discussion, additional information about stress responses has become 
available (e.g., Houser et al. (2020); Houser et al. (2021)). However, 
the additional studies do not change the expected potential impacts of 
stress on marine mammals from exposure to the Navy's activities.
    NMFS thoroughly discussed each of the strikes with the Navy, and 
summarized the circumstances surrounding each strike in the Estimated 
Take From Vessel Strikes and Explosives by Serious Injury or Mortality 
section of the 2023 HSTT proposed rule ((88 FR 68290, October 3, 2023) 
and the Authorized Take From Vessel Strikes and Explosives by Serious 
Injury or Mortality section of this final rule. The circumstances 
surrounding whale detection ahead of each strike varied. However, of 
note, Navy vessels routinely successfully maneuver to avoid large 
whales. Between 2009 and 2021 (the most recent year for which data is 
available), U.S. Navy vessels in the SOCAL portion of the HSTT Study 
Area maneuvered 316 times to avoid large whales during MTEs. The years

[[Page 4963]]

2017 and 2021 had the highest number of maneuvers (n = 64 and n = 82, 
respectively). In all years for which data is available (2009 to 2021), 
Navy cruisers and destroyers account for 51 to 100 percent of maneuvers 
during MTEs to avoid whales.
    Comment 19: A commenter, referencing two news articles, stated that 
new information indicates that the Navy is increasingly using unmanned 
systems, which cannot replace human monitoring, even if useful in 
addition to the lookouts and observers NMFS relies on to mitigate and 
monitor the impacts of the Navy's activities on marine mammals.
    Response: As stated in the 2023 HSTT proposed rule (88 FR 68290, 
October 3, 2023), the Navy's proposed activities have not changed from 
that analyzed in the 2018 final rule (83 FR 66846, December 27, 2018) 
or the 2020 final rule (85 FR 41780, July 10, 2020). Impacts from all 
unmanned systems that would be used in training and testing activities 
under this proposed rule have been accounted for in the analysis. 
Neither NMFS nor the Navy have proposed to replace human marine mammal 
monitoring with monitoring by unmanned systems.

Determinations

    Comment 20: A commenter stated that NMFS has neither adequately 
evaluated nor met the negligible impact standard for the following 
reasons:
    1. The negligible impact determination dismisses the important fact 
that vessel strikes already pose a substantial threat to large whales 
in the region, and several populations are already exceeding PBR. 
Endangered blue whales, threatened and endangered humpback whales, and 
endangered fin whales off the coast of Southern California are 
particularly vulnerable, with even one additional ship strike 
constituting a significant impact.
    2. NMFS has failed to consider the impacts of the full scope of 
training exercises over 7 years on marine mammals, including joint 
training exercises with foreign fleets. The commenter further asserted 
that what is not unsaid in the rule, but is critically important, is 
that the Navy's activities over 7 years (in contrast to the five 
already authorized) has never been evaluated under the MMPA, ESA, or 
NEPA. The commenter stated that this underscores that NMFS has not 
taken the measures needed to ensure the Navy's activities in the HSTT 
Study Area will have no more than a negligible impact on endangered 
whales and other marine mammals in the Pacific Ocean over the full 7 
years of the proposed authorization. NMFS must reexamine the increased 
risk and incidence of vessel strikes in light of the Navy's full suite 
of impacts on large whales and other marine mammals (over this extended 
period of time) and decline to authorize this additional take.
    Response: NMFS disagrees with the commenter's assertion that it has 
not adequately evaluated nor met the negligible impact standard. NMFS 
assessed all of the best available information about the relative risk 
of vessel strikes by commercial, recreational, and military vessels in 
the Vessel Strike section of this final rule. As explained in the 
Serious Injury or Mortality subsection of the Analysis and Negligible 
Impact Determination section of the 2018 HSTT final rule, the 2020 HSTT 
final rule, and this final rule, NMFS may find the impact of the 
authorized take from a specified activity to be negligible even if 
total human-caused mortality exceeds PBR, if the authorized mortality 
is less than 10 percent of PBR and management measures are being taken 
to address serious injuries and mortalities from the other activities 
causing mortality (i.e., other than the specified activities covered by 
the incidental take authorization in consideration, including vessel 
strike from other actions). When those considerations are applied in 
the section 101(a)(5)(A) context here, the authorized lethal take (0.14 
annually) of humpback whales from the Mainland Mexico- CA/OR/WA stock, 
and blue whales from the Eastern North Pacific stock are less than 10 
percent of PBR (less than 1 percent for humpback whales from the 
Mainland Mexico- CA/OR/WA stock and 3 percent for blue whales from the 
Eastern North Pacific stock). The authorized lethal take (0.57 
annually) of fin whales from the CA/OR/WA stock is less than 10 percent 
of PBR also (less than 1 percent). There are management measures in 
place to address the mortality and serious injury from the activities 
other than those the Navy is conducting. For the complete discussion of 
how NMFS carefully considered potential mortalities from the Navy's 
activities in light of PBR levels, including an explanation for why 
mortality above PBR will not necessarily induce population-level non-
negligible impacts, see the discussion in this rule, the 2020 HSTT 
final rule, and the 2018 HSTT final rule.
    NMFS acknowledges that the removal of a reproductive female (or any 
female) could be more impactful to the status of a population than the 
removal of a male. However, the PBR framework that supports the 
negligible impact finding inherently considers the likelihood that the 
human-caused mortalities being considered may consist of a random 
distribution of individuals of different sex in different life stages. 
Also, beyond the low likelihood of striking a whale at all, the 
likelihood of hitting a female is even lower.
    It is important to note that the only change to the number of takes 
proposed by the 2023 HSTT proposed rule was to the take by vessel 
strike to account for new information since publication of the 2020 
HSTT final rule. The 2020 HSTT final rule analyzed and authorized take 
of marine mammals over a 7-year period, not 5 years as noted by the 
commenter, and NMFS conducted the appropriate level of MMPA, ESA, and 
NEPA analysis to comply with both statutes during the promulgation of 
the 2020 HSTT final rule.
    As stated in the Preliminary Analysis and Negligible Impact 
Determination section of the 2023 HSTT proposed rule (88 FR 68290, 
October 3, 2023) and the Analysis and Negligible Impact Determination 
section of this final rule, while this rule consists of a modification 
of take by M/SI by vessel strike, NMFS considers the impacts of the 
entire specified activity and the total taking in the negligible impact 
determination. In consideration of the total taking, including take by 
mortality, Level A harassment, and Level B harassment, NMFS finds that 
the incidental take from the specified activities will have a 
negligible impact on all affected marine mammal species and stocks. 
Consistent with 40 CFR 1502.9 and the information and analysis 
contained in this final rule, the Navy and NMFS as a cooperating agency 
made a determination that this final rule and the subsequent LOAs will 
not result in significant impacts that were not fully considered in the 
2018 HSTT FEIS/OEIS. As indicated in the 2023 HSTT proposed rule, the 
Navy has made no substantial changes to the activities nor are there 
significant new circumstances or information relevant to environmental 
concerns or their impacts.
    NMFS and the Navy reinitiated consultation under the ESA. NMFS 
issued a reinitiated Biological and Conference Opinion on June 3, 2024 
concluding that the issuance of the 2024 HSTT final rule and subsequent 
LOAs are not likely to jeopardize the continued existence of the 
threatened and endangered species under NMFS' jurisdiction and are not 
likely to result in the destruction or adverse modification of critical 
habitat in the HSTT Study Area. The opinion is

[[Page 4964]]

available at https://doi.org/10.25923/7y9x-vw84.
    Please also see NMFS' response to Comment 7 regarding foreign 
vessels.
    Comment 21: Commenters stated that they oppose this proposed 
promulgation of modified regulations and associated LOAs for the Navy 
because it is not consistent with MMPA mandates that require NMFS to 
ensure activities have no more than a negligible impact on marine 
mammal species or stocks and that they have the least practicable 
adverse impact on marine mammal species, stocks, and habitat. In a 
related comment, a commenter stated that this rule would disregard the 
previously established boundaries between the Navy and NMFS and would 
also disregard the push the United States claims to have for the 
protection of marine wildlife. The commenter stated that it perceives 
the request to be heavily hypocritical of the same government that 
implemented regulations to protect marine wildlife that teeter on the 
edge of the endangered species list, to reach for an exception for its 
military, and further that the proposed amendment is unethical, 
hypocritical, and unnecessary.
    Response: The MMPA requires NMFS to authorize the incidental take 
of marine mammals by specified activities upon request if certain 
findings are made (16 U.S.C. 1371(a)(5)(A)). Here, the Navy submitted 
an application requesting two additional takes of large whales by 
serious injury or mortality by vessel strike through modification of 
the existing regulations and LOAs. As required by the MMPA, NMFS 
conducted the analysis described in the 2023 HSTT proposed rule and 
this final rule and made all required findings (preliminarily, in the 
case of the 2023 HSTT proposed rule), including finding that the Navy's 
activities will have a negligible impact on marine mammals and that the 
required mitigation measures will effect the least practicable adverse 
impact on marine mammals. Therefore, promulgation of this final rule is 
appropriate.
    Please see the Mitigation Measures section of this final rule for 
additional discussion of the required mitigation measures and NMFS' 
least practicable adverse impact finding.

Other Regulatory Processes

    Comment 22: A commenter stated that the Navy issued an EIS 
purporting to analyze the environmental impacts of its training and 
testing activities in the HSTT Study Area. NMFS was a cooperating 
agency for the 2018 HSTT FEIS/OEIS. The EIS considered only three 
alternatives in detail: the No Action Alternative under which the 
Navy's training activities would not occur; Alternative 1 that 
considered fluctuations in training cycles, testing requirements, and 
deployment schedules based on global demand and other factors and 
included the Navy's entire suite of mitigation measures; and 
Alternative 2 that considered a higher number of training exercises and 
sonar hours than in Alternative 1 and included the Navy's entire suite 
of mitigation measures. Alternative 1 was the preferred and adopted 
alternative. The commenter stated that none of the Navy's alternatives 
considered in detail an alternative that would require mandatory speed 
limits to avoid collisions with endangered whales.
    Response: While none of the Navy's alternatives considered in the 
2018 HSTT FEIS/OEIS include mandatory vessel speed limits, the Navy 
conducted an operational analysis of potential mitigation throughout 
the entire Study Area to consider a wide range of mitigation options, 
including but not limited to vessel speed restrictions. As discussed in 
chapter 3, section 3.0.3.3.4.1 (Vessels and In-Water Devices) of the 
2018 HSTT FEIS/OEIS, Navy ships transit at speeds that are optimal for 
fuel conservation or to meet operational requirements. Operational 
input indicated that implementing additional vessel speed restrictions 
beyond what is identified in chapter 5 (Mitigation), section 5.4 
(Mitigation Areas to be Implemented) of the 2018 HSTT FEIS/OEIS would 
be impracticable to implement due to implications for safety and 
sustainability. In its assessment of potential mitigation, the Navy 
considered implementing additional vessel speed restrictions (e.g., 
expanding the 10 kn (18.5 km per hour) restriction to other 
activities). The Navy determined that implementing additional vessel 
speed restrictions beyond what is described in chapter 5 (Mitigation), 
section 5.5.2.2 (Restricting Vessel Speed) of the 2018 HSTT FEIS/OEIS 
would be impracticable due to implications for safety (the ability to 
avoid potential hazards), sustainability (maintain readiness), and the 
Navy's ability to continue meeting its Title 10 requirements to 
successfully accomplish military readiness objectives. Additionally, as 
described in chapter 5 (Mitigation), section 5.5.2.2 (Restricting 
Vessel Speed) of the 2018 HSTT FEIS/OEIS, any additional vessel speed 
restrictions would prevent vessel operators from gaining skill 
proficiency, would prevent the Navy from properly testing vessel 
capabilities, or would increase the time on station during training or 
testing activities as required to achieve skill proficiency or properly 
test vessel capabilities, which would significantly increase fuel 
consumption. As discussed in chapter 5 (Mitigation), section 5.3.4.1 
(Vessel Movement) of the 2018 HSTT FEIS/OEIS, the Navy implements 
mitigation to avoid vessel strikes throughout the Study Area. 
Additionally, this final rule includes two new mitigation measures 
beyond that required by the 2020 HSTT final rule and modification of 
two existing mitigation measures. These measures are described in 
response to Comment 15 and the Mitigation Measures section of this 
final rule.
    Comment 23: A commenter stated that agencies must prepare 
supplemental EISs if: ``(i) The agency makes substantial changes in the 
proposed action that are relevant to environmental concerns; or (ii) 
There are significant new circumstances or information relevant to 
environmental concerns and bearing on the proposed action or its 
impacts'' (40 CFR 1502.9(d)(1)). The commenter stated that because 
these triggers have been met, it urges NMFS to prepare a supplemental 
EIS on the basis of the new information that has come to light since 
2018, including on the impacts of vessel strikes on large whales and on 
alternatives that reduce vessel strike impacts to marine mammals.
    Response: NMFS disagrees with the commenter that supplemental NEPA 
evaluation is warranted. As described in the National Environmental 
Policy Act section herein, consistent with 40 CFR 1502.9(d) and the 
information and analysis contained in this rule, the Navy and NMFS as a 
cooperating agency have determined that this final rule and any 
subsequent LOAs would not result in significant impacts that were not 
fully considered in the 2018 HSTT FEIS/OEIS. As indicated in this final 
rule and a supplemental information report prepared by NMFS, the Navy 
has made no substantial changes to the activities that are relevant to 
environmental concerns; nor are there substantial new circumstances or 
information about the significance of adverse effects that bear on the 
analysis.
    Comment 24: A commenter stated that despite the new 2020 
authorization--and the additional extensive take and other impacts it 
enables--NMFS has not completed new ESA consultation or a supplemental 
NEPA evaluation. The Navy is operating under the 2018 BiOp and 2018 
EIS. Since NMFS issued the 2018 BiOp and EIS, a slew of new 
information--in addition to the expanded scope of the Navy's

[[Page 4965]]

activities--indicates that the Navy's activities in the HSTT Study Area 
are likely affecting ESA-listed species to an extent not previously 
considered.
    In a related comment regarding ESA compliance, a commenter stated 
that the proposed rule states, ``NMFS has also reinitiated consultation 
internally on the issuance of these proposed, revised regulations and 
LOAs under section 101(a)(5)(A) of the MMPA.'' The commenter noted that 
when reinitiation is required, ``the original opinion loses its 
validity, as does its accompanying incidental take statement, which 
then no longer shields the action agency from penalties for takings'' 
(Ctr. for Biological Diversity v. BLM, 698 F.3d 1101, 1108 (9th Cir. 
2012)). A commenter stated that it awaits the conclusion of this 
reinitiated consultation and expects a revised biological opinion that 
fully complies with the ESA's standards.
    Response: NMFS has fully complied with the ESA and NEPA. NMFS 
described the ESA section 7 consultation history for this action in the 
Endangered Species Act section of the 2023 HSTT proposed rule and this 
final rule. As described in that section, NMFS consulted internally on 
the issuance of the 2018 HSTT regulations and LOAs under section 
101(a)(5)(A) of the MMPA.
    NMFS issued a Biological Opinion on December 10, 2018 concluding 
that the issuance of the 2018 HSTT final rule and subsequent LOAs are 
not likely to jeopardize the continued existence of the threatened and 
endangered species under NMFS' jurisdiction and are not likely to 
result in the destruction or adverse modification of critical habitat 
in the HSTT Study Area. The 2018 Biological Opinion included specified 
conditions under which NMFS would be required to reinitiate section 7 
consultation. NMFS reviewed these specified conditions for the 2020 
HSTT rulemaking and determined that reinitiation of consultation was 
not warranted. The incidental take statement that accompanied the 2018 
Biological Opinion was amended to cover the 7-year period of the 2020 
HSTT rule. The 2018 Biological Opinion for this action is available at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
    The 2018 Biological Opinion reinitiation clause (2), states that 
formal consultation should be reinitiated if ``new information reveals 
effects of the agency action that may affect ESA-listed species or 
critical habitat in a manner or to an extent not previously 
considered.'' Given the new information regarding the recent occurrence 
of large whale strikes by naval vessels in the southern California 
portion of the HSTT Study Area, as described herein, the Navy has 
reinitiated consultation with NMFS pursuant to section 7 of the ESA for 
HSTT Study Area activities, and NMFS has also reinitiated consultation 
internally on the issuance of the revised regulations and LOAs under 
section 101(a)(5)(A) of the MMPA. On June 3, 2024, NMFS issued a 2024 
reinitiated Biological and Conference Opinion concluding that the 
issuance of the rule and subsequent LOAs is not likely to jeopardize 
the continued existence of the threatened and endangered species under 
NMFS' jurisdiction and are not likely to result in the destruction or 
adverse modification of critical habitat in the HSTT Study Area. The 
2024 reinitiated Biological and Conference Opinion for this action is 
available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
    NMFS is aware of the statement in Ctr. for Biological Diversity v. 
BLM, 698 F.3d 1101, 1108 (9th Cir. 2012) referenced by the commenter. 
NMFS' position is that a biological opinion, including its Incidental 
Take Statement, for which formal consultation has been re-initiated 
remains valid and effective during the consultation and until a new 
biological opinion is issued. When the new biological opinion with a 
new ITS is issued, it supersedes and replaces the previous opinion and 
ITS.
    Please see NMFS' response to Comment 23 regarding NEPA compliance.

Changes From the Proposed Rule to the Final Rule

    NMFS has added two additional reporting requirements since 
publication of the 2023 HSTT proposed rule. First, the Navy's annual 
HSTT Training Exercise Report and Testing Activity Report must include 
information that tracks the Navy's implementation of the new SOCAL 
large whale aggregation real-time reporting mitigation measure. The 
report must include the following information for each instance that an 
aggregation of large whales is reported: (1) the date, time and general 
location (e.g., approximately 10-12 nmi SE of San Clemente Island) of 
the whales when the aggregation was first sighted; (2) the total number 
of whales observed within 1 nmi of a Navy vessel that make up the 
aggregation; and (3) the approximate distance (or distances if more 
than one group of whales is sighted) of the vessel from the whales in 
the aggregation when the whales were first sighted. To the extent 
practicable, this information should be provided in the Navy's 
unclassified version of these reports.
    Second, the Navy's annual HSTT Training Exercise Report and Testing 
Activity Report must include a confirmation 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 U.S. Navy's 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, which formed the basis of the acoustic impacts 
effects analysis used to estimate take in this final rule.
    NMFS has also made a non-substantive name change in the final rule. 
Ziphius cavirostris has multiple common names. In the 2018 HSTT final 
rule, 2020 HSTT final rule, and 2023 HSTT proposed rule, NMFS used the 
common name Cuvier's beaked whale. In this final rule, NMFS uses the 
common name goose-beaked whale instead.
    Last, NMFS made several non-substantive changes to the regulations 
to add clarity and improve readability.

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

    Marine mammal species and their associated stocks that have the 
potential to occur in the HSTT Study Area are presented in table 1 
along with the best/minimum abundance estimate and associated 
coefficient of variation value. Consistent with the 2018 HSTT final 
rule and 2020 HSTT final rule, the Navy anticipates the take of 
individuals from 38 marine mammal species by Level A harassment and 
Level B harassment incidental to training and testing activities from 
the use of sonar and other transducers, in-water detonations, air guns, 
and impact pile driving/vibratory extraction activities. As described 
in detail later, serious injury or mortality of six species is also 
analyzed and authorized. Two marine mammal species, the Hawaiian monk 
seal and the Main Hawaiian Islands Insular DPS of false killer whale, 
have critical habitat designated under the ESA (16 U.S.C. 1531 et seq.) 
in the HSTT Study Area.
    In the 2018 HSTT proposed rule and 2018 HSTT final rule, we 
presented a detailed discussion of marine mammals and their occurrence 
in the HSTT Study Area, inclusive of important marine mammal habitat 
(e.g., ESA-designated critical habitat), BIAs, national marine 
sanctuaries (NMSs), and unusual

[[Page 4966]]

mortality events (UMEs). Please see these rules and the 2017 and 2019 
Navy applications for additional information beyond what is provided 
herein. While there have been some minor changes described here, there 
have been no changes to important marine mammal habitat, NMSs, or ESA-
designated critical habitat since the issuance of the 2018 HSTT final 
rule that change our determination of which species or stocks have the 
potential to be affected by the Navy's activities or the information in 
the Description of Marine Mammals and Their Habitat in the Area of the 
Specified Activities section in the 2019 HSTT proposed rule and 2020 
HSTT final rule. Therefore, the information presented in those sections 
of the 2019 HSTT proposed rule and 2020 HSTT final rule remains current 
and valid with the exception of the information about UMEs, BIAs, and 
revised humpback whale stock structures, discussed below.
    On April 21, 2021, NMFS designated critical habitat for the 
endangered Western North Pacific DPS, the endangered Central America 
DPS, and the threatened Mexico DPS of humpback whales (86 FR 21082). 
Areas proposed as critical habitat include specific marine areas 
located off the coasts of California, Oregon, Washington, and Alaska. 
None of the designated critical habitat overlaps with the HSTT Study 
Area. One of the proposed areas, critical habitat Unit 19, would have 
overlapped with the SOCAL range in the HSTT Study Area but was excluded 
after consideration of potential national security and economic impacts 
of designation. NMFS, in the final rule designating critical habitat 
for humpback whales, identified prey species, primarily euphausiids and 
small pelagic schooling fishes of sufficient quality, abundance, and 
accessibility within humpback whale feeding areas to support feeding 
and population growth, as an essential habitat feature. NMFS, through a 
critical habitat review team (CHRT), also considered inclusion of 
migratory corridors and passage features, as well as sound and the 
soundscape, as essential habitat features. NMFS did not include either 
in the final critical habitat, however, as the CHRT concluded that the 
best available science did not allow for identification of any 
consistently used migratory corridors or definition of any physical, 
essential migratory or passage conditions for whales transiting between 
or within habitats of the three DPSs. The best available science also 
currently does not enable NMFS to identify particular sound levels or 
to describe a certain soundscape feature that is essential to the 
conservation of humpback whales. Regardless of whether critical habitat 
is designated for a particular area, NMFS has considered all applicable 
information regarding marine mammals and their habitat in the analysis 
supporting these final regulations.
    NMFS has reviewed the 2023 SARs (Carretta et al. 2024, Young et al. 
2024). For all species except humpback whale, NMFS determined that 
neither the SARs nor any other new information changes our 
determination in the 2020 HSTT final rule of which species or stocks 
have the potential to be affected by the Navy's activities. For 
humpback whale, the 2023 final SARs include a revision to the humpback 
whale stock structure in the Pacific Ocean. In the 2020 HSTT final 
rule, NMFS authorized take of the CA/OR/WA stock and Central North 
Pacific stock of humpback whale. Given the revised stock structure, in 
this final rule, NMFS has reanalyzed the potential for take of each 
stock of humpback whale and determined that the Central America/
Southern Mexico-CA/OR/WA, Mainland Mexico--CA/OR/WA stock, and Hawaii 
stocks are likely to be taken by the Navy's activities. Please refer to 
the 2023 Alaska and Pacific Ocean SARs for additional information about 
these new stocks.
    The species considered but not carried forward for analysis are two 
American Samoa stocks of spinner dolphins--(1) the Kure and Midway 
stock and (2) the Pearl and Hermes stock. There is no potential for 
overlap with any stressors from Navy activities and therefore there 
would be no incidental takes, therefore, these stocks are not 
considered further.

                                              Table 1--Marine Mammal Occurrence Within the HSTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                  Status                                                 Stock abundance
          Common name            Scientific name         Stock      ---------------------------------    Occurrence        Seasonal       (CV)/minimum
                                                                          MMPA             ESA                              absence        population
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale....................  Balaenoptera       Eastern North     Strategic,      Endangered       Southern          -               1,898 (0.085)/
                                 musculus.          Pacific.          Depleted                         California.                       1,767.
                                                   Central North     Strategic,      Endangered       Hawaii..........  Summer          133 (1.09)/63.
                                                    Pacific.          Depleted
Bryde's whale.................  Balaenoptera       Eastern Tropical  -               -                Southern          -               unknown.
                                 brydei/edeni.      Pacific.                                           California.
                                                   Hawaii..........  -               -                Hawaii..........  -               791 (0.29)/623.
Fin whale.....................  Balaenoptera       CA/OR/WA........  Strategic,      Endangered       Southern          -               11,065 (0.405)/
                                 physalus.                            Depleted                         California.                       7,970.
                                                   Hawaii..........  Strategic,      Endangered       Hawaii..........  Summer          203 (0.99)/101.
                                                                      Depleted
Humpback whale................  Megaptera          Central America/  Strategic       Endangered \1\   Southern          Winter          1,496 (0.171)/
                                 novaeangliae.      Southern                                           California.                       1,284.
                                                    Mexico--CA/OR/
                                                    WA.
                                                   Mainland Mexico-- Strategic       Threatened \1\   Southern          Winter          3,477 (0.101)/
                                                    CA/OR/WA.                                          California.                       3,185.
                                                   Hawai[revaps]i..  -               - \1\            Hawaii..........  Summer          11,278 (0.56)/
                                                                                                                                         7,265.
Minke whale...................  Balaenoptera       CA/OR/WA........  -               -                Southern          -               915 (0.792)/509.
                                 acutorostrata.                                                        California.
                                                   Hawaii..........  -               -                Hawaii..........  Summer          438 (1.05)/212.
Sei whale.....................  Balaenoptera       Eastern North     Strategic,      Endangered       Southern          -               864 (0.40)/625.
                                 borealis.          Pacific.          Depleted                         California.
                                                   Hawaii..........  Strategic,      Endangered       Hawaii..........  Summer          391 (0.9)/204.
                                                                      Depleted
Gray whale....................  Eschrichtius       Eastern North     -               -                Southern          -               26,960 (0.05)/
                                 robustus.          Pacific.                                           California.                       25,849.
                                                   Western North     Strategic,      Endangered       Southern          -               290 (NA)/271.
                                                    Pacific.          Depleted                         California.

[[Page 4967]]

 
Sperm whale...................  Physeter           CA/OR/WA........  Strategic,      Endangered       Southern          -               2,606 (0.135)/
                                 macrocephalus.                       Depleted                         California.                       2,011.
                                                   Hawaii..........  Strategic,      Endangered       Hawaii..........  -               5,707 (0.23)/
                                                                      Depleted                                                           4,486.
Pygmy sperm whale.............  Kogia breviceps..  CA/OR/WA........  -               -                Southern          Winter and      4,111 (1.12)/
                                                                                                       California.       Fall            1,924.
                                                   Hawaii..........  -               -                Hawaii..........  -               42,083 (0.64)
                                                                                                                                         25,695.
Dwarf sperm whale.............  Kogia sima.......  CA/OR/WA........  -               -                Southern          -               unknown.
                                                                                                       California.
                                                   Hawaii..........  -               -                Hawaii..........  -               unknown.
Baird's beaked whale..........  Berardius bairdii  CA/OR/WA........  -               -                Southern          -               1,363
                                                                                                       California.                      (0.53)/894.
Blainville's beaked whale.....  Mesoplodon         Hawaii..........  -               -                Hawaii..........  -               1,132 (0.99)/
                                 densirostris.                                                                                           564.
Goose-beaked whale \2\........  Ziphius            CA/OR/WA........  -               -                Southern          -               5,454 (0.27)/
                                 cavirostris.                                                          California.                       4,214.
                                                   Hawaii..........  -               -                Hawaii..........  -               4,431 0.41/
                                                                                                                                         3,180.
Longman's beaked whale........  Indopacetus        Hawaii..........  -               -                Hawaii..........  -               2,550 (0.67)/
                                 pacificus.                                                                                              1,527.
Mesoplodont beaked whales.....  Mesoplodon spp...  CA/OR/WA........  -               -                Southern          -               3,044 (0.54)/
                                                                                                       California.                       1,967.
Common Bottlenose dolphin.....  Tursiops           California        -               -                Southern          -               453 (0.06)/346.
                                 truncatus.         Coastal.                                           California.
                                                   CA/OR/WA          -               -                Southern          -               3,477 (0.696)/
                                                    Offshore.                                          California.                       2,048.
                                                   Hawaii Pelagic..  -               -                Hawaii..........  -               unknown.
                                                   Kauai and Niihau  -               -                Hawaii..........  -               112 (0.24)/92.
                                                   Oahu............  -               -                Hawaii..........  -               112 (0.17)/97.
                                                   Maui Nui \3\....  -               -                Hawaii..........  -               64 (0.15)/56.
                                                   Hawaii Island...  -               -                Hawaii..........  -               136 (0.43)/96.
False killer whale............  Pseudorca          Main Hawaiian     Strategic,      Endangered       Hawaii..........  -               167 (0.14)/149.
                                 crassidens.        Islands Insular   Depleted
                                                    \4\.
                                                   Hawaii Pelagic..  -               -                Hawaii..........  -               5,528 (0.35)/
                                                                                                                                         4,152.
                                                   Northwestern      -               -                Hawaii..........  ..............  477 (1.71)/178.
                                                    Hawaiian
                                                    Islands.
Fraser's dolphin..............  Lagenodelphis      Hawaii..........  ..............  ...............  Hawaii..........  -               40,960 (0.7)/
                                 hosei.                                                                                                  24,068.
Killer whale..................  Orcinus orca.....  Eastern North     -               -                Southern          -               300 (0.1)/276.
                                                    Pacific                                            California.
                                                    Offshore.
                                                   West Coast        -               -                Southern          -               349 (N/A)/349.
                                                    Transient.                                         California.
                                                   Hawaii..........  -               -                Hawaii..........  -               161 (1.06)/78.
Long-beaked common dolphin....  Delphinus          California......  -               -                Southern          -               83,379 (0.216)/
                                 capensis.                                                             California.                       69,636.
Melon-headed whale............  Peponocephala      Hawaiian Islands  -               -                Hawaii..........  -               40,647 (0.74)/
                                 electra.                                                                                                23,301.
                                                   Kohala Resident.  -               -                Hawaii..........  -               unknown.
Northern right whale dolphin..  Lissodelphis       CA/OR/WA........  -               -                Southern          -               29,285 (0.72)/
                                 borealis.                                                             California.                       17,024.
Pacific white-sided dolphin...  Lagenorhynchus     CA/OR/WA........  -               -                Southern          -               34,999 (0.222)/
                                 obliquidens.                                                          California.                       29,090.
Pantropical spotted dolphin...  Stenella           Oahu............  -               -                Hawaii..........  -               unknown.
                                 attenuata.
                                                   Maui Nui \3\....  -               -                Hawaii..........  -               unknown.
                                                   Hawaii Island...  -               -                Hawaii..........  -               unknown.
                                                   Hawaii Pelagic..  -               -                Hawaii..........  -               67,313 (0.27)/
                                                                                                                                         53,839.
Pygmy killer whale............  Feresa attenuata.  Tropical........  -               -                Southern          Winter &        unknown.
                                                                                                       California.       Spring
                                                   Hawaii..........  -               -                Hawaii..........  -               10,328 (0.75)/
                                                                                                                                         5,885.
Risso's dolphins..............  Grampus griseus..  CA/OR/WA........  -               -                Southern          -               6,336 (0.32)/
                                                                                                       California.                       4,817.
                                                   Hawaii..........  -               -                Hawaii..........  -               6,979 (0.29)/
                                                                                                                                         5,283.
Rough-toothed dolphin.........  Steno bredanensis  NSD \5\.........  -               -                Southern          -               unknown.
                                                                                                       California.
                                                   Hawaii..........  -               -                Hawaii..........  -               83,915 (0.49)/
                                                                                                                                         56,782.
Short-beaked common dolphin...  Delphinus delphis  CA/OR/WA........  -               -                Southern          -               1,056,308 (0.21)/
                                                                                                       California.                       888,971.
Short-finned pilot whale......  Globicephala       CA/OR/WA........  -               -                Southern          -               836 (0.79)/466.
                                 macrorhynchus.                                                        California.
                                                   Hawaii..........  -               -                Hawaii..........  -               19,242 (0.23)/
                                                                                                                                         15,894.
Spinner dolphin...............  Stenella           Hawaii Pelagic..  -               -                Hawaii..........  -               unknown.
                                 longirostris.
                                                   Hawaii Island...  -               -                Hawaii..........  -               665 (0.09)/617.

[[Page 4968]]

 
                                                   Oahu and 4-       -               -                Hawaii..........  -               unknown.
                                                    Islands.
                                                   Kauai and Niihau  -               -                Hawaii..........  -               unknown.
                                                   Kure and Midway.  -               -                Hawaii..........  -               unknown.
                                                   Pearl and Hermes  -               -                Hawaii..........  -               unknown.
Striped dolphin...............  Stenella           CA/OR/WA........  -               -                Southern          -               29,988 (0.3)/
                                 coeruleoalba.                                                         California.                       23,448.
                                                   Hawaii..........  -               -                Hawaii..........  -               64,343 (0.28)/
                                                                                                                                         51,055.
Dall's porpoise...............  Phocoenoides       CA/OR/WA........  -               -                Southern          -               16,498 (0.61)/
                                 dalli.                                                                California.                       10,286.
Harbor seal...................  Phoca vitulina...  California......  -               -                Southern          -               30,968 (NA)/
                                                                                                       California.                       27,348.
Hawaiian monk seal............  Neomonachus        Hawaii..........  Strategic,      Endangered       Hawaii..........  -               1,564 (0.05)/
                                 schauinslandi.                       Depleted                                                           1,444.
Northern elephant seal........  Mirounga           California......  -               -                Southern          -               187,386 (NA)/
                                 angustirostris.                                                       California.                       85,369.
California sea lion...........  Zalophus           U.S. Stock......  -               -                Southern          -               257,606 (NA)/
                                 californianus.                                                        California.                       233,515.
Guadalupe fur seal............  Arctocephalus      Mexico to         Strategic,      Threatened       Southern          -               34,187 (NA)/
                                 townsendi.         California.       Depleted                         California.                       31,019.
Northern fur seal.............  Callorhinus        California......  Depleted        -                Southern          -               14,050 (NA)/
                                 ursinus.                                                              California.                       7,524.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: A ``-'' indicates that this column does not apply.
\1\ The Mainland Mexico--CA/OR/WA stock and the Mexico--North Pacific stock (which does not occur in the HSTT Study Area) of humpback whale comprise the
  Mexico DPS. The Hawai[revaps]i stock comprises the Hawai[revaps]i DPS. The Central America/Southern Mexico--CA/OR/WA stock comprises the Central
  America DPS.
\2\ Ziphius cavirostris has multiple common names. In the 2018 HSTT final rule, 2020 HSTT final rule, and 2023 HSTT proposed rule, NMFS used the common
  name Cuvier's beaked whale. In this final rule, NMFS uses the common name goose-beaked whale instead.
\3\ The ``4-Islands'' stocks of common bottlenose dolphin and pantropical spotted dolphin are now the ``Maui Nui'' stocks.
\4\ NMFS relied on the 2022 final SAR for this stock.
\5\ NSD--No stock designation. Rough-toothed dolphin has a range known to include the waters off Southern California, but there is no recognized stock
  or data available for the U.S. West Coast.

Unusual Mortality Events

    An UME is defined under section 410(6) of the MMPA as a stranding 
that is unexpected, involves a significant die-off of any marine mammal 
population, and demands immediate response. From 1991 to the present, 
there have been 17 formally recognized UMEs affecting marine mammals in 
California and Hawaii and involving species under NMFS' jurisdiction.
    At the time of publication of the 2023 HSTT proposed rule, there 
was an active UME for gray whales which NMFS fully considered in its 
analysis (88 FR 68290, October 3, 2023). This UME was closed on 
November 9, 2023. The UME involved 690 gray whale strandings, including 
347 in the United States, 316 in Mexico, and 27 in Canada. Strandings 
occurred from Alaska to Mexico along the west coast of North America, 
including in the whale's wintering, migratory, and feeding areas. The 
Investigative Team concluded that the preliminary cause of the UME was 
localized ecosystem changes in the whale's Subarctic and Arctic feeding 
areas that led to changes in food, malnutrition, decreased birth rates, 
and increased mortality all documented during the UME. Please see 
https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2023-eastern-north-pacific-gray-whale-ume-closed for additional information 
on this UME.

Biologically Important Areas

    Kratofil et al. (2023) identified updated BIAs in Hawaii. The HSTT 
Study Area overlaps the updated BIAs for small and resident populations 
of the following species in Hawaii: spinner dolphin, short-finned pilot 
whale, rough-toothed dolphin, pygmy killer whale, pantropical spotted 
dolphin, melon-headed whale, false killer whale, dwarf sperm whale, 
goose-beaked whale, common bottlenose dolphin, and Blainville's beaked 
whale. Further, the HSTT Study Area overlaps updated BIAs for humpback 
whale reproduction in Hawaii. The updated BIAs overlap critical Navy 
training and testing areas within the HSTT Study Area, including most 
of the internal Navy operating areas. Please see Kratofil et al. (2023) 
for additional details about the BIAs.
    Since publication of the 2023 HSTT proposed rule, Calambokidis et 
al. (2024) identified updated BIAs on the West Coast of the U.S. The 
HSTT Study Area overlaps feeding BIAs for blue whale and fin whale in 
SOCAL. Additionally, it overlaps a reproductive BIA as well as 
northbound and southbound migratory BIAs for gray whale. Please see 
Calambokidis et al. (2024) for additional details about the BIAs.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section provides a discussion of the ways in which components 
of the specified activity may impact marine mammals and their habitat. 
The Estimated Take section later in this document includes a 
quantitative analysis of the number of individuals that are expected to 
be taken by this activity. The Analysis and Negligible Impact 
Determination section considers the content of this section, the 
Estimated Take section, and the Mitigation Measures section, to draw 
conclusions regarding the likely impacts of these activities on the 
reproductive success or survivorship of individuals and whether those 
impacts are reasonably expected to, or reasonably likely to, adversely 
affect the species or stock through effects on annual rates of 
recruitment or survival. In the Potential Effects of Specified 
Activities on Marine Mammals and Their Habitat section of the 2018 HSTT 
proposed and final rules, and as updated by the 2020 HSTT final rule, 
NMFS provided a description of the ways marine mammals may be affected 
by the same activities that the Navy will be conducting during the 7-
year period analyzed in this rulemaking in the form of serious injury 
or mortality, physical trauma, sensory impairment (permanent and 
temporary threshold shifts and acoustic masking),

[[Page 4969]]

physiological responses (particularly stress responses), behavioral 
disturbance, or habitat effects. Further, in the 2023 HSTT proposed 
rule, we summarized any new relevant information from the scientific 
literature since publication of the 2020 HSTT final rule. We do not 
repeat the information here, all of which remains current and 
applicable, but refer the reader to those rules and the 2018 HSTT FEIS/
OEIS (chapter 3, section 3.7 Marine Mammals), which NMFS participated 
in the development of via our cooperating agency status and adopted to 
meet our NEPA requirements.
    In the Potential Effects of Specified Activities on Marine Mammals 
and Their Habitat section of the 2018 HSTT final rule, we stated that 
it has been speculated for some time that beaked whales might have 
unusual sensitivities to sonar sound due to their likelihood of 
stranding in conjunction with MFAS use, although few definitive causal 
relationships between MFAS use and strandings have been documented, and 
no such findings have been documented with Navy use in Hawaii and 
southern California. On March 25, 2022, a beaked whale (species 
unknown) stranded in Honaunau Bay, Hawaii. The animal was observed 
swimming into shore and over rocks. Bystanders intervened to turn the 
animal off of the rocks, and it swam back out of the Bay on its own. 
Locals reported hearing a siren or alarm type of sound underwater on 
the same day, and a Navy vessel was observed from shore on the 
following day. The Navy confirmed it used CAS within 50 km (27 nmi) and 
48 hours of the time of stranding, though the stranding has not been 
definitively linked to the Navy's CAS use.
    An initial study of another deep diving odontocete, the sperm 
whale, found similar behavioral responses and reductions in foraging 
when whales were exposed to PAS and CAS at similar cumulative Sound 
Exposure Levels (SELcum), even though the CAS signal had a 
lower source level than the PAS signal. This may indicate that animals 
were, in this case, responding to the cumulative energy of a signal 
rather than the instantaneous amplitude (Cure et al. 2021, Isojunno et 
al. 2020). If a beaked whale were inshore of a Navy vessel using either 
PAS or CAS MFAS, and responded by moving away from the vessel, they 
could find themselves in shallow water and become disoriented, as may 
have happened in the case of Honaunau Bay. In addition, the animal was 
not seen after it returned to sea, so blood tissue samples could not be 
obtained. There has been a growing body of literature about the impacts 
of new pathogens on the health and stranding of marine mammals, 
including beaked whales in Hawaii and other locations in the Pacific 
(e.g., Clifton et al. 2023 and West et al. 2013).
    NMFS has reviewed new relevant information from the scientific 
literature since publication of the 2023 HSTT proposed rule. Further, 
in the 2023 HSTT proposed rule, we summarized any new relevant 
information from the scientific literature since publication of the 
2020 HSTT final rule. Summaries of the new key scientific literature 
reviewed since publication of the 2023 HSTT proposed rule are presented 
below. The literature generally falls into the following topic areas: 
Vessel Strike; Hearing, Vocalization, and Masking; Hearing Loss 
(Temporary Threshold Shift (TTS) and Permanent Threshold Shift (PTS)); 
Behavioral Reactions; Stranding; Population Consequences of Disturbance 
and Cumulative Stressors; Methodology for Assessing Acoustic Impacts.

Vessel Strike

    Dunlop (2024) studied migrating east Australian humpback whales' 
response to approaching vessels to determine if individuals exhibited 
an avoidance response. While some select groups did display changes in 
their movements, the sampled collective did not display any consistent 
vessel avoidance response. Furthermore, the degree of avoidance was 
lower as vessels approached at faster speeds. Overall, the results 
showed that humpbacks were generally unresponsive to approaching 
vessels regardless of the speed or noise level at which they 
approached. Female-calf pairs proved to be the biggest exception to 
this pattern; though this demographic did not exhibit a consistent 
response as a whole, these pairs were more likely to change their 
travel pattern more than any other group. Due to the lack of response 
from the population, the results suggest that implementation of vessel 
strike avoidance protocols is critical for successfully conserving 
large whale populations.
    Redfern et al. (2024) developed a new metric for analyzing vessel 
strike risk reduction (``PLETHd'') and applied it to North Atlantic 
right, humpback, fin, and sei whale distributions along the U.S. East 
Coast. The metric is calculated using three parameters: the 
relationship between vessel speed and the probability that a strike is 
lethal, vessel transit distance, and whale distributions. The authors 
compared the impact of a 14 kn (25.9 km/hr) vs. 10 kn (18.5 km/hr) 
speed restriction and found that only the 10 kn (18.5 km/hr) reduction 
substantially reduced risk. The authors also found that applying a 10 
kn (18.5 km/hr) speed restriction within multiple whale species' 
critical habitat zones was almost as effective as enacting the same 
speed restriction along the entire East Coast Exclusive Economic Zone 
(EEZ). The results suggest that 10 kn (18.5 km/hr) speed restrictions 
are a robust method for reducing vessel strike risk and that vessel 
restrictions within high-density core areas of a marine mammal's 
habitat can be highly impactful.

Hearing, Vocalization, and Masking

    Parnell et al. (2024) studied the soundscapes of four underwater 
Hawaiian monk seal critical habitats, including measurement of ambient 
noise and characterization of detected sound sources. The authors 
observed diel patterns in both anthropogenic and biological sound 
sources that mask acoustic communication in Hawaiian monk seals. The 
measurements collected for this study provide a baseline for future 
research on impacts of anthropogenic activities on these soundscapes.
    A multi-national team of scientists (U.S. and Norway) obtained the 
first hearing measurements of a mysticete species through auditory 
evoked potential (AEP) tests. During the 2023 field season, AEP tests 
were conducted on two adolescent female minke whales in Norway (Houser 
et al. 2024). Houser et al. (2024) indicate that the minke whale's 
upper-frequency limit of hearing occurs somewhere between 45 to 90 kHz. 
Minke whale's high-frequency sensitivity is hypothesized to support 
detection of the echolocation clicks of one their predators, the killer 
whale. The bandwidth of the tone-bursts used in the Houser et al. 
(2024) AEP testing was too broad to define the precise upper-frequency 
limit, but indicates this species is more sensitive to higher 
frequencies than previously predicted based on inner ear anatomy and 
vocalization data (Southall et al. 2019; NMFS 2024). Results from their 
final 2024 field season, which included further examination of the 
upper-frequency limit of hearing, are expected to be published in 2025, 
with preliminary data from two additional whales indicating that minke 
whale hearing is best around 32 kHz.

Hearing Loss (TTS and PTS)

    Gransier and Kastelein (2024) examined TTS susceptibility in harbor 
porpoises and harbor seals based on exposures varying in frequency 
range and level. Specifically, exposures consisted of 100% duty cycle 
one-sixth-

[[Page 4970]]

octave noise bands at frequencies covering the entire hearing range of 
each species. Despite these species having different audiograms and 
regions of best sensitivity (i.e., underwater pinnipeds are sensitive 
to sounds ranging from approximately 0.01 to 40-60kHz, while most 
odontocetes are sensitive sounds ranging from approximately 0.25 to 80-
125kHz), the frequency-specific susceptibility to TTS was similar 
amongst both species, with the greatest susceptibility to TTS occurring 
at frequencies from 22.5 to 50 kHz and least susceptible to sounds 
below 10 kHz. The frequency of minimum TTS for the harbor seal aligns 
with its frequency of best hearing, while frequency of minimum TTS for 
the harbor porpoise is well below the frequency of best hearing. This 
study illustrates that the audiogram does not always serve as a good 
predictor of frequency-dependent susceptibility to TTS, with the 
pattern of susceptibility to TTS in these two species being more 
comparable than their audiograms.
    Brewer et al. (2023) described 41 call types of Cook Inlet beluga 
vocal behavior and classified them into three categories: (1) whistles, 
(2) pulsed calls, and (3) combined calls. These are the first 
descriptions of vocal repertoire of this species in two critical 
habitat locations and across multiple seasons. Call types were then 
used to investigate the potential for masking from commercial ship 
noise. It was found that call types (0-12 kHz) were partially masked by 
distant ship noise and completely masked by close ship noise. This 
study provides evidence that ship noise can impact vocal communication 
of this population. Specifically Cook Inlet beluga vocalizations in the 
Susitna area, seven of the beluga's most common calls are either 
partially or fully masked by commercial ship traffic.
    Kastelein et al. (2024) examined TTS in two California sea lions 
exposed to one-sixth-octave noise band centered at 32 kHz for 60-
minutes of exposure, resulting in cumulative sound exposure levels 
(SELcum) ranging from 168 to 192 dB. Hearing after exposure 
was examined at the center frequency of the fatiguing sound (32 kHz) 
and at half an octave (44.8 kHz) and one octave above the center 
frequency (63 kHz). Higher SELcum resulted in greater 
threshold shifts. Furthermore, the greatest TTS occurred at half an 
octave above the center frequency, with TTS onset (6 dB threshold 
shift) measured at 44.8 kHz occurring at a 179 dB SELcum. 
TTS patterns and recovery was similar between the two individuals, with 
TTSs up to 6.7 dB recovering within 8 minutes of exposure, TTSs up to 
12 dB recovering within an hour, and only the highest TTS measured 
(12.9 dB) taking over an hour to recover. The results of this study 
were directly incorporated in the Navy's updated Phase IV AUD INJ/TTS 
criteria and indicate that California sea lions have lower AUD INJ/TTS 
onset than previously predicted (Southall et al. 2019).

Behavioral Reactions

    Ceciarini et al. (2023) tested the efficacy of Acoustic Deterrent 
Devices for minimizing common bottlenose dolphin interactions with 
trammel nets in the Northern Tyrrhenian Sea. The authors used 
interactive pingers which emitted output signals ``from 5 up to 500 kHz 
at 168 dB re 1 [mu]Pa at 1 m as random high-speed tones FM ranging from 
100 [mu]s up to seconds''. The study found that catch damage from 
dolphins was significantly lower in nets where pingers were used.
    Elmegaard et al. (2023) exposed six harbor porpoises to Acoustic 
Harassment Devices (AHDs), commonly referred to as ``seal scarers'', to 
determine if they would exhibit any physiological or behavioral 
reactions. The AHDs pulsed at 14 kHz with a source level of 189 dB re 1 
[micro]Pa (rms) or sound exposure level of 184 dB re 1 [micro]Pa\2\s, 
with porpoise RLs ranging from 98-132 dB re 1 [micro]Pa. All 
individuals sampled exhibited a mixture of behavioral or physiological 
responses, including startling, increased distance from the sound 
source, increased swim speed, diving, altered echolocation patterns, 
cardiac responses, or altered respiration patterns. Overall, responses 
were observed in every individual up to 7 km or down to an RL of 98 dB 
re 1 [micro]Pa.
    Frankish et al. (2023) followed ten harbor porpoises for 5 to 10 
days to observe their reactions to ship traffic around Denmark. The 
porpoises spent over half of the study period within 10 km of a ship, 
and a third of the study period exposed to noise levels above ambient. 
The porpoises responded by moving away from ships during the day, and 
diving deep during the night. They had a higher likelihood of altering 
their movements when louder ships were nearby (maximum probability of 
deterrence = 12.2 percent during the day and 14.9 percent at night), 
and moved an average of 3.2 km away from 13.6 different ships every 
day. Deeper dives occurred less frequently, at a rate of 5.7 different 
ships per individual per night. The porpoises also reacted to loud 
ships that were far away (>2 km at 93  14 dB re 1 
[mu]Pa\2\), though responses occurred less frequently (5 to 9 percent 
of the time vs. up to 14.9 percent of the time at close range).
    Southall et al. (2023) used control exposure experiments (CEEs) to 
provide the first results in examining the impact of mid-frequency navy 
sonar (3.5-4.1 kHz) or pseudorandom noise (similar frequency, duration 
and source and received level compared to mid-frequency sonar) on fin 
whale behavior in feeding habitats of the Southern California Bight. Of 
the 15 exposed fin whales, only five individuals demonstrated a mild to 
moderate behavioral changes (avoidance, changes in feeding, diving, or 
respiration), with no changes demonstrated for whales in the six 
control exposures. Compared to blue whales, fin whale behavioral 
responses were more limited in occurrence, severity and duration and 
were found to be less dependent upon contextual aspects of exposure, 
with received level as the primary factor associated with behavioral 
responses. Additionally, foraging success was not compromised by 
exposures from this study. The authors note that differences observed 
between behavioral response in fin whales in this study and blue whales 
in previously published studies may be attributed to the smaller sample 
size associated with this study. However, as seen in blue whales, fin 
whale behavior returned to baseline conditions after noise exposure 
ended.

Methodology for Assessing Acoustic Impacts

    Indeck et al. (2024) assessed North Atlantic right whale, fin, and 
blue whale detectability by Slocum gliders near heavily used shipping 
lanes in the Gulf of St. Lawrence, Canada. The goal of the study was to 
evaluate the gliders' suitability as a passive acoustic monitoring 
platform for whale detection in areas with high anthropogenic noise 
levels. The authors found that shipping lane noise did not 
substantially impact whale detectability, as calls from the highly 
trafficked areas were not masked significantly more than calls in 
quieter areas nearby. The gliders were therefore identified as a viable 
PAM platform to use in and around busy shipping areas. These results 
suggest that gliders could be an important tool for monitoring 
mysticetes in highly industrialized areas and assisting in ongoing 
dynamic management initiatives.

Conclusion for New Pertinent Science Since Publication of the 2023 HSTT 
Proposed Rule

    Having considered the best scientific information available, 
specifically new relevant information published since the 2023 HSTT 
proposed rule, we have

[[Page 4971]]

determined that there is no new information that substantively affects 
our analysis of impacts on marine mammals and their habitat that 
appeared in the 2020 HSTT final rule, all of which remains applicable 
and valid for our assessment of the effects of the Navy's activities 
during the 7-year period of this rulemaking.

Estimated Take of Marine Mammals

    This section indicates the number of takes that NMFS is 
authorizing, which are based on the amount of take that NMFS 
anticipates could occur or is likely to occur, depending on the type of 
take and the methods used to estimate it, as described below. NMFS 
coordinated closely with the Navy in the development of their 
incidental take application and agrees that the methods the Navy has 
put forth described herein, in the 2019 HSTT proposed rule, 2020 HSTT 
final rule, and in the 2018 HSTT proposed and final rules 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, with the exception of that of humpback 
whales, discussed further below. The number and type of incidental 
takes that could occur or are likely to occur annually remain identical 
to those authorized in the 2018 HSTT regulations and 2020 HSTT 
regulations, with the exception of authorized takes by serious injury 
or mortality by vessel strike and harassment takes of humpback whale 
stocks in Southern California (due to the new stock structure).
    Takes are predominantly in the form of harassment, but a small 
number of serious injuries or mortalities could occur. For military 
readiness activities, the MMPA defines ``harassment'' as (i) any act 
that injures or has the significant potential to injure a marine mammal 
or marine mammal stock in the wild (Level A harassment); or (ii) any 
act that disturbs or is likely to disturb a marine mammal or marine 
mammal stock in the wild by causing disruption of natural behavioral 
patterns, including, but not limited to, migration, surfacing, nursing, 
breeding, feeding, or sheltering, to a point where such behavioral 
patterns are abandoned or significantly altered (Level B harassment).
    Authorized takes will primarily be in the form of Level B 
harassment, as use of the acoustic and explosive sources (i.e., sonar, 
air guns, pile driving, explosives) is more likely to result in the 
disruption of natural behavior 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) or TTS for marine mammals. There is also the potential for 
Level A harassment in the form of auditory injury and/or tissue damage 
(the latter from explosives only) to result from exposure to the sound 
sources utilized in training and testing activities. Additionally, 
serious injuries or mortalities of mysticetes (except for sei whales, 
minke whales, Bryde's whales, Central North Pacific stock of blue 
whales, Hawaii stock of fin whales, Western North Pacific stock of gray 
whales, and sperm whales) could occur through vessel strike. Mitigation 
and monitoring measures are expected to minimize the severity of the 
taking to the extent practicable.
    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 will be ensonified above these levels in a day or event; (3) 
the density or occurrence of marine mammals within these ensonified 
areas; and (4) the number of days of activities or events.

Acoustic Thresholds

    Using the best available science, NMFS, in coordination with the 
Navy, has established acoustic thresholds that identify the most 
appropriate received level of underwater sound above which marine 
mammals exposed to these sound sources could be reasonably expected to 
experience a disruption in behavior patterns to a point where they are 
abandoned or significantly altered, either directly or via the effects 
of TTS (both equated to Level B harassment) or PTS of some degree 
(equated to Level A harassment). Thresholds have also been developed to 
identify the pressure levels above which animals may incur non-auditory 
injury from exposure to pressure waves from explosive detonation. We 
described the acoustic thresholds and the methods used to determine 
thresholds in detail in the Acoustic Thresholds section of the 2018 
HSTT final rule; please see the 2018 HSTT final rule for detailed 
information. Further, in the 2020 HSTT final rule, and 2023 HSTT 
proposed rule, we described new relevant information from the 
scientific literature since publication of the 2018 HSTT final rule and 
2020 HSTT final rule, respectively. Since publication of the 2023 HSTT 
proposed rule, NMFS has updated our Technical Guidance (NMFS, 2024) 
containing updated acoustic criteria for auditory injury (89 FR 36762, 
October 24, 2024). The Technical Guidance provides updated auditory 
injury thresholds, where appropriate, as well as revised weighting 
functions, in some cases. For impulsive sources, the Updated Technical 
Guidance's auditory injury thresholds generally remain identical or are 
higher compared to our 2018 Technical Guidance, meaning that received 
levels would need to be higher in order for marine mammals to be 
expected to incur auditory injury. The exceptions are for phocid 
pinnipeds (PW), where the cumulative SEL threshold, in the Updated 
Technical Guidance, is 2 dB lower and for otariid pinnipeds (OW) where 
the peak sound pressure level threshold is 2 dB lower and the 
cumulative SEL threshold is 18 dB lower. As for the Updated Technical 
Guidance's weighting functions, for MF cetaceans (now called HF 
cetaceans in the updated document) and HF cetaceans (now called VHF 
cetaceans in the updated document), the weighting functions reflect a 
higher susceptibility to auditory injury at frequencies below 10 kHz, 
as compared to the 2018 Technical Guidance. Other minor changes/shifts 
to weighting functions (e.g., for LF cetaceans, PW pinnipeds, OW 
pinnipeds) were also included. This new information was not available 
in a timeframe in which NMFS could have incorporated it into the 
quantitative analysis supporting this final rulemaking; however, NMFS 
did consider the information qualitatively. While these changes in the 
auditory injury thresholds and weighting functions could result in 
minor increases in PTS exposure estimates for some species, given the 
conservative assumptions built into the take estimate methodology, they 
would not be expected to result in meaningful, if any, changes in take 
estimates and would not be expected to change any of the findings.

Navy's Acoustic Effects Model

    The Navy proposed no changes to the Acoustic Effects Model as 
described in the 2018 HSTT final rule (and incorporated by reference in 
the 2020 HSTT final rule), and there is no new information that would 
affect the applicability or validity of the model. Please see the 2018 
HSTT final and proposed rules and Appendix E of the 2018 HSTT FEIS/OEIS 
for detailed information, and see the discussion of the 2024 Technical 
Guidance in the Acoustic Thresholds section above.

[[Page 4972]]

Range to Effects

    The Navy proposed no changes from the 2018 HSTT final rule (and 
subsequent 2020 HSTT final rule) to the type and nature of the 
specified activities to be conducted during the 7-year period analyzed 
in this final rule, including equipment and sources used and exercises 
conducted.
    As described above in the Acoustic Thresholds section, since 
publication of the 2023 HSTT proposed rule, NMFS has updated our 
Technical Guidance (NMFS, 2024) containing updated acoustic criteria 
for auditory injury (89 FR 36762). Please see that section for a full 
discussion of the updates. This new information was not available in a 
timeframe in which NMFS could have incorporated it into the 
quantitative analysis supporting this final rulemaking; however, NMFS 
did consider the information qualitatively. While these changes in the 
auditory injury thresholds and weighting functions could result in 
minor increases in PTS exposure estimates for some species, given the 
conservative assumptions built into the take estimate methodology, they 
would not be expected to result in meaningful, if any, changes in take 
estimates and would not be expected to change any of the findings.
    Therefore, the ranges to effects in this final rule are identical 
to those described and analyzed in the 2018 HSTT final rule and 2020 
HSTT final rule, including received sound levels that may cause onset 
of significant behavioral response and TTS and PTS in hearing for each 
source type or explosives that may cause non-auditory injury. Please 
see the Range to Effects section and tables 24 through 40 of the 2018 
HSTT final rule for detailed information.

Marine Mammal Density

    The Navy proposed no changes to the methods used to estimate marine 
mammal density described in the 2018 HSTT final rule, and there is no 
new information that would affect the applicability or validity of 
these methods or change the results in a manner that would change the 
necessary determinations supporting the issuance of these regulations. 
The Navy's estimate of marine mammal density as described in the 2018 
HSTT final rule remains valid, though, as described herein, NMFS has 
incorporated new information regarding humpback whale stock structure 
into its analysis. Please see the 2018 HSTT final rule, and below, for 
detailed information.
    As noted above, NMFS regularly updates SARs, and in this rulemaking 
considers the 2023 final SARs (Carretta et al. 2024, Young et al. 
2024). While these SARs contain updated information, the Navy's 
estimate of marine mammal density as described in the 2018 HSTT final 
rule remains valid for the following reasons. The Navy uses its Marine 
Species Density Database (NMSDD) for its analysis, which is derived 
from multiple sources, including but not limited to SARs. In contrast, 
for most cetacean species, the SAR is estimated using line-transect 
surveys or mark-recapture studies (e.g., Barlow, 2010; Barlow and 
Forney, 2007; Calambokidis et al. 2008). The result provides one single 
abundance value for each species across broad geographic areas, but it 
does not provide information on the species density or concentrations 
within that area, and it does not estimate density for other timeframes 
or seasons that were not surveyed. A change in a stock's abundance 
indicated in a SAR does not necessarily indicate a change in that 
stock's density in any given area. Therefore, stocks in the HSTT Study 
Area with higher abundance estimates in the most recent SARs in 
comparison to the abundance estimates at the time that marine mammal 
densities were derived for the HSTT Study Area do not necessarily now 
occur in higher densities in the HSTT Study Area. For humpback whale, 
while the stock structure in the Pacific Ocean was revised in the 2022 
final SARs (Carretta et al. 2023, Young et al. 2023), the discussion 
above remains true regarding density of humpback whales in the HSTT 
Study Area across all stocks.

Take Requests

    As in the 2018 HSTT final rule and 2020 HSTT final rule, the Navy 
determined that the three stressors below could result in the 
incidental taking of marine mammals. NMFS has reviewed the Navy's data 
and analysis and determined that it is complete and accurate, and NMFS 
agrees that the following stressors have the potential to result in 
takes of marine mammals from the Navy's planned activities:
     Acoustics (sonar and other transducers; air guns; pile 
driving/extraction);
     Explosives (explosive shock wave and sound, assumed to 
encompass the risk due to fragmentation); and
     Physical Disturbance and Strike (vessel strike).
    NMFS reviewed and agrees with the Navy's conclusion that acoustic 
and explosive sources have the potential to result in incidental takes 
of marine mammals by harassment, serious injury, or mortality. NMFS 
carefully reviewed the Navy's analysis and conducted its own analysis 
of vessel strikes, determining that the likelihood of any particular 
species of large whale being struck is quite low. However, as noted 
previously, in 2021, two separate U.S. Navy vessels struck unidentified 
large whales on two separate occasions, one whale in June 2021 and one 
whale in July 2021. In May 2023, the U.S. Navy struck a large whale, 
which based on available photos and video, NMFS and the Navy have 
determined was either a fin whale or sei whale. NMFS agrees that vessel 
strikes have the potential to result in incidental take from serious 
injury or mortality for certain species of large whales, and the Navy 
has specifically requested coverage for these species. Therefore, the 
likelihood of vessel strikes, and later the effects of the incidental 
take that is being authorized, has been fully analyzed and is described 
below.
    Regarding the quantification of expected takes from acoustic and 
explosive sources (by Level A and Level B harassment, as well as 
mortality resulting from exposure to explosives), the number of takes 
are based directly on the level of activities (days, hours, counts, 
etc., of different activities and events) in a given year. In the 2020 
HSTT final rule, take estimates across the 7 years were based on the 
Navy conducting 4 years of a representative level of activity and 3 
years of maximum level of activity. As in the 2020 HSTT final rule, the 
Navy uses the maximum annual level to calculate annual takes (which 
would remain identical to what was determined in the 2020 HSTT final 
rule, with the exception of attribution of takes to humpback whale 
stocks), and the sum of all years (4 representative and 3 maximum) to 
calculate the 7-year totals for this rulemaking.
    The quantitative analysis process used for the 2018 HSTT FEIS/OEIS 
and the 2017 and 2019 Navy applications to estimate potential exposures 
to marine mammals resulting from acoustic and explosive stressors is 
detailed in the technical report titled Quantifying Acoustic Impacts on 
Marine Mammals and Sea Turtles: Methods and Analytical Approach for 
Phase III Training and Testing (U.S. Department of the Navy, 2018). The 
Navy Acoustic Effects Model estimates acoustic and explosive effects 
without taking mitigation into account; therefore, the model 
overestimates predicted impacts on marine mammals within mitigation 
zones. To account for mitigation for marine species in the take 
estimates, the

[[Page 4973]]

Navy conducts a quantitative assessment of mitigation. The Navy 
conservatively quantifies the manner in which procedural mitigation is 
expected to reduce the risk for model-estimated PTS for exposures to 
sonars and for model-estimated mortality for exposures to explosives, 
based on species sightability, observation area, visibility, and the 
ability to exercise positive control over the sound source. Where the 
analysis indicates mitigation would effectively reduce risk, the model-
estimated PTS are considered reduced to TTS and the model-estimated 
mortalities are considered reduced to injury. For a complete 
explanation of the process for assessing the effects of mitigation, see 
the 2017 Navy application and the Take Requests section of the 2018 
HSTT final rule. The extent to which the mitigation areas reduce 
impacts on the affected species and stocks is addressed separately in 
the Analysis and Negligible Impact Determination section.
    No changes have been made to the quantitative analysis process to 
estimate potential exposures to marine mammals resulting from acoustic 
and explosive stressors and calculate take estimates, with the 
exception of take of humpback whales to account for the change in stock 
structure. Please see the documents described in the paragraph above, 
the 2018 HSTT proposed rule, the 2018 HSTT final rule, and below for 
detailed descriptions of these analyses. While Oedekoven and Thomas 
(2022) suggest that detection of marine mammals is less certain than 
previously assumed at certain distances, NMFS has independently 
evaluated the Navy's method for application of mitigation effectiveness 
in estimating take and agrees that it is appropriately applied to 
augment the model in the prediction and authorization of injury and 
mortality as described in the rule, including after consideration of 
Oedekoven and Thomas (2022). In summary, we believe the Navy's methods, 
including the method for incorporating mitigation and avoidance, are 
the most appropriate methods for predicting PTS, TTS, and behavioral 
disturbance. But even with the consideration of mitigation and 
avoidance, given some of the more conservative components of the 
methodology (e.g., the thresholds do not consider ear recovery between 
pulses), we would describe the application of these methods as 
identifying the maximum number of instances in which marine mammals 
would be reasonably expected to be taken through PTS, TTS, or 
behavioral disturbance.
Summary of Authorized Take From Training and Testing Activities
    Based on the methods discussed in the previous sections and the 
Navy's model and quantitative assessment of mitigation, the Navy 
provided its take estimate and request for authorization of takes 
incidental to the use of acoustic and explosive sources for training 
and testing activities both annually (based on the maximum number of 
activities that could occur per 12-month period) and over the 7-year 
period in its 2019 rulemaking/LOA application. With the exception of 
changes to humpback whale take, described below, annual takes (based on 
the maximum number of activities that could occur per 12-month period) 
from the use of acoustic and explosive sources are identical to those 
presented in tables 41 and 42 and in the Explosives subsection of the 
Take Requests section of the 2018 HSTT final rule. The 2022 Navy 
application includes the Navy's updated take estimate and request for 
take by vessel strike due to vessel movement in the HSTT Study Area. 
NMFS reviewed the Navy's data, methodology, and analysis and determined 
that it was complete, but NMFS has reanalyzed the potential for vessel 
strike following the May 2023 strike, as described in the Authorized 
Take from Vessel Strikes and Explosives by Serious Injury or Mortality 
section. NMFS agrees that the estimates for incidental takes by 
harassment from all sources as well as the incidental takes by serious 
injury or mortality from explosives requested for authorization are the 
maximum number of instances in which marine mammals are reasonably 
expected to be taken at the time of Navy's request, and continues to be 
for all stocks other than humpback whales, for which changes are 
described below. NMFS also agrees that the takes by serious injury or 
mortality as a result of vessel strikes could occur. Note that, 
consistent with the 2020 HSTT final rule, the total amount of estimated 
incidental take from acoustic and explosive sources over the total 7-
year period covered by the 2019 Navy application is less than the 
annual total multiplied by seven. Although the annual estimates are 
based on the maximum number of activities per year and therefore, the 
maximum possible estimated takes, the 7-year total take estimates are 
based on the sum of 3 maximum years and 4 representative years, with 
the exception of humpback whale stocks that occur in SOCAL for which 7-
year total take is conservatively estimated as the annual total 
multiplied by seven. Not all activities occur every year. Some 
activities would occur multiple times within a year, and some 
activities would occur only a few times over the course of the 7-year 
period. Using 7 years of the maximum number of activities each year 
would vastly overestimate the amount of incidental take that would 
occur over the 7-year period where the Navy knows that it will not 
conduct the maximum number of activities each and every year for the 7 
years.
    As described above in the Description of Marine Mammals and Their 
Habitat in the Area of the Specified Activities section, the 2022 final 
SARs include a revision to the humpback whale stock structure in the 
Pacific Ocean. In the 2020 HSTT final rule, NMFS authorized take of the 
CA/OR/WA stock and Central North Pacific stock of humpback whale. Given 
the revised stock structure, in this final rule, NMFS has reanalyzed 
the potential for take of each stock of humpback whale and determined 
that the Central America/Southern Mexico-CA/OR/WA, Mainland Mexico-CA/
OR/WA stock, and Hawaii stocks are likely to be taken by the Navy's 
activities.
    Under the new stock structure, the Hawaii stock (Hawaii DPS) is the 
only stock that would occur in Hawaii. Therefore, the Hawaii stock of 
humpback whale is the only humpback whale stock anticipated to be taken 
by the Navy's activities in the HRC, and all takes of the Central North 
Pacific stock of humpback whale that were authorized in the 2020 HSTT 
final rule are anticipated to be of individuals from the new Hawaii 
stock. In SOCAL, the takes of individuals from the former CA/OR/WA 
stock that were authorized in the 2020 HSTT final rule are anticipated 
to be of individuals from the new Central America/Southern Mexico-CA/
OR/WA and Mainland Mexico-CA/OR/WA stock.
    Please see the Authorized Harassment Take from Testing Activities 
and Authorized Harassment Take from Training Activities sections below 
for the authorized annual and 7-year total number and type of Level A 
harassment and Level B harassment for each humpback whale stock.

Authorized Harassment Take From Training Activities

    For training activities, table 11 of the 2020 HSTT final rule 
summarizes the Navy's take estimate and request in the 2019 Navy 
application and the maximum amount and type of Level A harassment and 
Level B harassment that NMFS concurred is reasonably expected to occur 
by species or stock and authorized in the 2020 HSTT LOA. In the 2022 
Navy application, the Navy

[[Page 4974]]

requested no change to this authorized take, though as described above, 
NMFS has since published the 2023 final, which include a revision to 
humpback whale stock structure. For the estimated 7-year total amount 
and type of Level A harassment and Level B harassment, see table 11 of 
the 2020 HSTT final rule for all species other than humpback whale. For 
the estimated amount and type of Level A harassment and Level B 
harassment annually, see table 41 in the 2018 HSTT final rule for all 
species other than humpback whale. Note that take by Level B harassment 
includes both behavioral disturbance and TTS. Navy figures 6-12 through 
6-50 in section 6 of the 2017 Navy application illustrate the 
comparative amounts of TTS and behavioral disturbance for each species 
annually, noting that if a modeled marine mammal was ``taken'' through 
exposure to both TTS and behavioral disturbance in the model, it was 
recorded as a TTS.

 Table 2--Humpback Whale Take From Acoustic and Explosive Effects for All Training Activities in the HSTT Study
                                                      Area
----------------------------------------------------------------------------------------------------------------
                                                              Annual                       7-year total
                                                 ---------------------------------------------------------------
            Species                   Stock           Level B         Level A         Level B         Level A
                                                    harassment      harassment      harassment      harassment
----------------------------------------------------------------------------------------------------------------
 Humpback whale \a\...........  Hawaii..........           5,604               1          34,437              12
                                Central America/             585               0       \b\ 4,095               0
                                 Southern Mexico-
                                 CA/OR/WA
                                 (Central
                                 America DPS).
                                Mainland Mexico--            669               1       \b\ 4,683               7
                                 CA/OR/WA
                                 (Mexico DPS).
----------------------------------------------------------------------------------------------------------------
\a\ Combined takes from the Central America/Southern Mexico- CA/OR/WA stock and the Mainland Mexico CA/OR/WA
  stock are equal to takes of the CA/OR/WA stock authorized in the 2020 HSTT final rule.
\b\ Unlike other species and stocks, for the Central America/Southern Mexico-CA/OR/WA stock and Mainland Mexico-
  CA/OR/WA stock, NMFS estimated the 7-year take by Level B harassment by multiplying the annual estimated take
  by seven. However, between the two stocks, NMFS does not anticipate that the total number of takes by Level B
  harassment across all 7 years would exceed the 7,962 takes by Level B harassment from training activities that
  were authorized for the CA/OR/WA stock of humpback whales in the 2020 HSTT final rule.

Authorized Harassment Take From Testing Activities
    For testing activities, table 12 of the 2020 HSTT final rule 
summarizes the Navy's take estimate and request in the 2019 Navy 
application and the maximum amount and type of Level A harassment and 
Level B harassment that NMFS concurred is reasonably expected to occur 
by species or stock and authorized in the 2020 HSTT LOA. In the 2022 
Navy application, the Navy requested no change to this authorized take. 
For the estimated 7-year total amount and type of Level A harassment 
and Level B harassment, see table 12 of the 2020 HSTT final rule. For 
the estimated amount and type of Level A harassment and Level B 
harassment annually, see table 42 in the 2018 HSTT final rule. Note 
that take by Level B harassment includes both behavioral disturbance 
and TTS. Navy figures 6-12 through 6-50 in section 6 of the 2017 Navy 
application illustrate the comparative amounts of TTS and behavioral 
disturbance for each species annually, noting that if a modeled marine 
mammal was ``taken'' through exposure to both TTS and behavioral 
disturbance in the model, it was recorded as a TTS.

  Table 3--Humpback Whale Take From Acoustic and Explosive Effects for All Testing Activities in the HSTT Study
                                                      Area
----------------------------------------------------------------------------------------------------------------
                                                              Annual                       7-year total
                                                 ---------------------------------------------------------------
            Species                   Stock           Level B         Level A         Level B         Level A
                                                    harassment      harassment      harassment      harassment
----------------------------------------------------------------------------------------------------------------
Humpback whale \a\............  Hawaii..........           3,522               2          23,750              19
                                Central America/             291               0       \b\ 2,037               0
                                 Southern Mexico-
                                 CA/OR/WA.
                                Mainland Mexico--            449               0       \b\ 3,143               0
                                 CA/OR/WA.
----------------------------------------------------------------------------------------------------------------
\a\ Combined takes from the Central America/Southern Mexico- CA/OR/WA stock and the Mainland Mexico CA/OR/WA
  stock are equal to takes of the CA/OR/WA stock authorized in the 2020 HSTT final rule.
\b\ Unlike other species and stocks, for the Central America/Southern Mexico-CA/OR/WA stock and Mainland Mexico-
  CA/OR/WA stock, NMFS estimated the 7-year take by Level B harassment by multiplying the annual estimated take
  by seven. However, between the two stocks, NMFS does not anticipate that the total number of takes by Level B
  harassment across all 7 years would exceed the 4,961 takes by Level B harassment from testing activities that
  were authorized for the CA/OR/WA stock of humpback whales in the 2020 HSTT final rule.

Authorized Take From Vessel Strikes and Explosives by Serious Injury or 
Mortality

Vessel Strike
    Vessel strikes from commercial, recreational, and military vessels 
are known to affect large whales and have resulted in serious injury 
and fatalities to cetaceans (Abramson et al. 2011; Berman-Kowalewski et 
al. 2010; Calambokidis, 2012; Douglas et al. 2008; Laggner, 2009; 
Lammers et al. 2003; Van der Hoop et al. 2012; Van der Hoop et al. 
2013; Crum et al. 2019). Records of collisions date back to the early 
17th century, and the worldwide number of collisions appears to have 
increased steadily during recent decades (Laist et al. 2001; Ritter 
2012) due to increases in the number and speed of large vessels, 
increased reporting of strikes, and increased abundance of some large 
whales (Ransome et al. 2021), among other factors.
    Numerous studies of interactions between surface vessels and marine

[[Page 4975]]

mammals have demonstrated that free-ranging marine mammals often, but 
not always (e.g., McKenna et al. 2015; Smultea et al. 2022; Szesciorka 
et al. 2019), engage in avoidance behavior when surface vessels move 
toward them. It is not clear whether these responses are caused by the 
physical presence of a surface vessel, the underwater noise generated 
by the vessel, or an interaction between the two (Amaral and Carlson, 
2005; Au and Green, 2000; Bain et al. 2006; Bauer 1986; Bejder et al. 
1999; Bejder and Lusseau, 2008; Bejder et al. 2009; Bryant et al. 1984; 
Corkeron, 1995; Erbe, 2002; F[eacute]lix, 2001; Goodwin and Cotton, 
2004; Lemon et al. 2006; Lusseau, 2003; Lusseau, 2006; Magalhaes et al. 
2002; Nowacek et al. 2001; Richter et al. 2003; Scheidat et al. 2004; 
Simmonds, 2005; Watkins, 1986; Williams et al. 2002; Wursig et al. 
1998). Several authors suggest that the noise generated during vessel 
movement is probably an important factor (Blane and Jaakson, 1994; 
Evans et al. 1992; Evans et al. 1994). Water disturbance may also be a 
factor. These studies suggest that the behavioral responses of marine 
mammals to surface vessels are similar to their behavioral responses to 
predators. Avoidance behavior is expected to be even stronger in the 
subset of instances during which the Navy is conducting training or 
testing activities using active sonar or explosives.
    The marine mammals most vulnerable to vessel strikes are those that 
spend extended periods of time at the surface to restore oxygen levels 
within their tissues after deep dives (e.g., sperm whales). In 
addition, some baleen whales seem generally unresponsive to vessel 
sound, making them more susceptible to vessel collisions (Nowacek et 
al. 2004). These species are primarily large whales.
    Some researchers have suggested the relative risk of a vessel 
strike can be assessed as a function of animal density and the 
magnitude of vessel traffic (e.g., Fonnesbeck et al. 2008; Vanderlaan 
et al. 2008). Differences among vessel types also influence the 
probability of a vessel strike. The ability of any ship to detect a 
marine mammal and avoid a collision depends on a variety of factors, 
including environmental conditions, ship design, size, speed, and 
ability and number of personnel observing, as well as the behavior of 
the animal. Vessel speed, size, and mass are all important factors in 
determining if injury or death of a marine mammal is likely due to a 
vessel strike. For large vessels, speed and angle of approach can 
influence the severity of a strike. For example, Vanderlaan and Taggart 
(2007) found that between vessel speeds of 8.6 and 15 kn (15.9 and 27.8 
km per hour), the probability that a vessel strike is lethal increases 
from 0.21 to 0.79. Large whales also do not have to be at the water's 
surface to be struck. Silber et al. (2010) found when a whale is below 
the surface (about one to two times the vessel draft), there is likely 
to be a pronounced propeller suction effect. This suction effect may 
draw the whale into the hull of the ship, increasing the probability of 
propeller strikes.
    There are some key differences between the operation of military 
and non-military vessels, which make the likelihood of a military 
vessel striking a whale lower than some other vessels (e.g., commercial 
merchant vessels). Key differences include:
     Many military ships have their bridges positioned closer 
to the bow, offering better visibility ahead of the ship (compared to a 
commercial merchant vessel);
     There are often aircraft associated with the training or 
testing activity (which can serve as Lookouts), which can more readily 
detect cetaceans in the vicinity of a vessel or ahead of a vessel's 
present course before crew on the vessel would be able to detect them;
     Military ships are generally more maneuverable than 
commercial merchant vessels, and if cetaceans are spotted in the path 
of the ship, could be capable of changing course more quickly;
     The crew size on military vessels is generally larger than 
merchant ships, allowing for stationing more trained Lookouts on the 
bridge. At all times when vessels are underway, trained Lookouts and 
bridge navigation teams are used to detect objects on the surface of 
the water ahead of the ship, including cetaceans. Additional Lookouts, 
beyond those already stationed on the bridge and on navigation teams, 
are positioned as Lookouts during some training events; and
     When submerged, submarines are generally slow moving (to 
avoid detection), and therefore, marine mammals at depth with a 
submarine are likely able to avoid collision with the submarine. When a 
submarine is transiting on the surface, there are Lookouts serving the 
same function as they do on surface ships.
    Vessel strike to marine mammals is not associated with any specific 
training or testing activity but is rather a limited and sporadic, but 
possible, accidental result of Navy vessel movement within the HSTT 
Study Area or while in transit.
    In 2009, the Navy began implementing additional mitigation measures 
to further reduce the likelihood of vessel strikes. Prior to the recent 
strikes in 2021 and 2023, there were two recorded U.S. Navy vessel 
strikes of large whales in the HSTT Study Area between 2009 and April 
2021, a period of approximately 12 years.
    Since 2021 there have been five strikes of large whales in SOCAL 
attributed to naval vessels, three by the U.S. Navy and two by the 
Royal Australian Navy. As stated previously, the U.S. Navy struck a 
large whale in waters off Southern California in May 2023. Based on 
available photos and video, NMFS and the Navy have determined this 
whale was either a fin whale or sei whale. The U.S. Navy struck two 
unidentified large whales during the months of June and July 2021, and 
prior to that, on May 7, 2021, the Royal Australian Navy HMAS Sydney, a 
147.5 m (161.3 yd) Hobart Class Destroyer, struck and killed two fin 
whales (a mother and her calf) while operating within SOCAL. In the 
case of the Royal Australian Navy strike, the carcasses were first 
sighted under the bow of the vessel while it was approaching the Naval 
Base in San Diego. The whales had been pinned to a sonar dome in the 
front of the vessel due to the force of water as the ship was underway. 
Based on interviews with HMAS Sydney personnel, the most likely time of 
impact with the two whales would have been around 6:25 a.m. when the 
vessel was located near Cortes Bank, and visibility was poor. The 
reported vessel speed at the estimated time of strike was 9 kn (16.7 km 
per hour). One minute before the estimated strike time a lookout 
reported whales off the starboard bow. The officer on-watch verbally 
acknowledged the report, slowed speed, and visually tracked the whales 
passing clear down the starboard side until they were clear of the 
ship. The morning of the strike, the HMAS Sydney was getting into 
position to participate in a U.S. Navy-led exercise later that day. Of 
note, throughout the remainder of the day visibility was poor and the 
vessel had implemented mitigation measures in multiple instances due to 
whale occurrence. In addition to being the only documented occurrence 
of a foreign military vessel strike of a large whale within the HSTT 
Study Area, the HMAS Sydney vessel strike was also somewhat unique, as 
compared to other reported military vessel strikes, in that two whales 
were apparently struck at one time, and both remained pinned to

[[Page 4976]]

the front of the vessel until the vessel approached the port.
    On June 29, 2021, a U.S. Navy cruiser struck an unknown whale 
species approximately 95 nmi (176 km) west of San Diego. The ship was 
returning from Hawaii, heading to a rendezvous with a fuel 
replenishment vessel (oiler) for an Underway Replenishment. Off-duty 
sailors noticed a group of whales approaching the ship from the port 
quarter (i.e., left rear of the ship), an area unique to cruisers with 
some equipment structures blocking close aboard sight. The first 
indication of a whale within the 500-yd mitigation zone immediately 
prior to the strike was when an off-duty sailor on the flight deck 
witnessed the whale briefly surface on the aft port quarter before 
diving. Shortly after this occurred blood was noticed in the wake, and 
a floating whale body was eventually observed behind the ship. The 
ship's speed was 25 kn (46.3 km per hour) at the estimated time the 
strike occurred. The Navy also noted that, on the morning before the 
strike occurred, the ship had maneuvered several times to avoid whale 
blows beyond the 500-yd (457.2 m) mitigation zone, closer to 1,000 yd 
(914.4 m).
    On July 11, 2021, a U.S. Navy cruiser struck an unknown whale 
species approximately 90 nmi (166.7 km) south-southwest of San Diego. 
The vessel was a participant in a MTE (Large Integrated Anti-Submarine 
Warfare--Composite Unit Training Exercise) within the SOCAL portion of 
the action area. The vessel was maneuvering for pending flight 
operations to receive an inbound helicopter. At 2:27 p.m., the 
starboard lookout sighted what they believed to be a whale crossing 
immediately under the vessel's bow. The conning officer attempted to 
maneuver the vessel by turning to port but internal watchstanders 
subsequently felt the ship shudder aft. The vessel's combat center 
observed a red slick 600 yd (548.6 m) astern on a flight deck camera 
and a brief surfacing of the whale itself, but no carcass was observed. 
There had not been any sightings of large whales off the bow leading up 
to the incident. Although the ship was traveling at 25-30 kn (46.3-55.6 
km per hour) 1 hour before the estimated strike time, at 10 minutes 
before, the vessel changed course and reduced its speed to 17 kn (31.5 
km per hour). These 2021 incidents were the first known U.S. Navy 
vessel strikes in the HSTT Study Area since 2009.
    On May 20, 2023, a U.S. Navy aircraft carrier was at sea conducting 
independent, unit-level flight training for the embarked airwing 
approximately 70 nmi (129.6 km) west of San Diego. Training exercises 
concluded for the day at approximately 7:44 p.m. local time. Navy 
personnel discovered a whale impinged on the bow of the vessel at 
approximately 8:00 p.m. local time. The vessel was traveling at 
approximately 5 kn (9.3 km per hour) and had recently made a turn to 
reset position for the evening when the Navy personnel discovered the 
whale. Navy personnel captured video and photos of the carcass, and 
based on those images, NMFS and the Navy have determined this whale was 
either a fin whale or sei whale; the two species are very similar 
morphologically and are difficult to distinguish from one another at 
sea. Navy personnel stopped the vessel to allow lack of momentum to 
dislodge the carcass from the bow, and based on lack of further 
observations after the carcass dislodged, it is believed to have sunk 
around 9:30 p.m. local time. Navy personnel on board the vessel 
reported that they did not feel an impact from striking the whale. 
Prior to the strike, between 6:45 p.m. and 7:45 p.m., the forward 
Lookouts on the vessel observed two whales crossing the vessel's bow 
but did not provide a distance between the vessel and the whales. One 
Lookout reported seeing the blow and the other reported seeing `humps' 
(presumably the dorsal of the animal). Both whales were sighted past 
the ship's course to the northwest. Within the same time window, one of 
the aft Lookouts observed a single whale swimming parallel to the ship 
and soon passed astern of the ship. During the same time, independent 
of the sightings and for general movement reasons, the ship changed 
speed from 17 kn (31.5 km per hour) to 10 kn (18.5 km per hour) at 7:22 
p.m.
    While in this incident a whale was discovered impinged on the bow 
of a Navy vessel, this incident is very different from the discovery of 
two fin whales discovered impinged on the sonar dome of a Royal 
Australian Navy vessel in 2021 when the vessel came to port at Naval 
Base San Diego. While U.S. Navy cannot speculate on the configurations 
of other ships bows and even sonar dome specifications (that may be at 
the bow), the Navy believes it would be implausible for a marine mammal 
to become lodged on the sonar dome of a U.S. Navy ship and remain 
undetected due to a technological standard operating procedure. Sonar 
domes on U.S. Navy ships have a pressurized rubber window that 
maintains 150 pound-force per square inch (PSI) through the ship's fire 
main. If anything affects the pressure, an alarm sounds in the sonar 
control room. In the event of a whale strike in that location, this 
alarm would alert personnel that something hit the sonar dome. Further, 
the shape, hydrodynamic design, construction using a non-abrasive 
material, and regular hull cleaning procedures to remove barnacles and 
other growth on U.S. Navy ships also make it unlikely that a whale 
would become lodged and remain undetected on a U.S. Navy ship's bow or 
even sonar dome. While in the case of the May 2023 strike, described 
above, a whale also became lodged on the ship's bow, the aircraft 
carrier that struck the whale does not have active or passive sonar 
capabilities (i.e., no sonar dome), nor does it have a bulbous bow, and 
the whale was more quickly discovered by Navy personnel.
    In March 2024 a dead fin whale was discovered off of Pier 10 in 
Naval Station San Diego within the Navy's security barrier. The 
security barrier, which consists of a series of connected floating 
sections, is intended to discourage unauthorized boat entry to the 
piers. The necropsy indicated that vessel strike was the most likely 
cause of death. Given the location the whale was discovered, this could 
have been the result of a military vessel strike. However, the Navy 
reviewed its vessel activity during that time frame and available 
observations of those vessels coming and going to port, as well as at 
port, and determined it was unlikely that the whale was carried into 
port by a Navy vessel. Based on this and other information from Navy's 
investigation, we cannot determine whether this whale was struck by a 
Navy vessel during HSTT activities or was struck by a commercial or 
other vessel and drifted into the Navy pier area.
    For the same reasons listed above describing why the likelihood of 
a military vessel striking a whale is lower than that of some other 
vessels striking whales, it is also highly unlikely that a Navy vessel 
would strike a whale, dolphin, porpoise, or pinniped without detecting 
it. Specifically, Navy vessels have Lookouts, including on the forward 
part of the ship that can visually detect a hit animal in the event 
ship personnel do not feel the strike (which has occurred). 
Accordingly, NMFS is confident that the Navy's reported strikes are 
accurate and appropriate for use in the analysis. The Navy has strict 
internal procedures and mitigation requirements include reporting of 
any vessel strikes of marine mammals, and the Navy's discipline, 
extensive training (not only for detecting marine mammals, but for 
detecting and reporting any potential navigational obstruction), and 
strict

[[Page 4977]]

chain of command give NMFS a high level of confidence that all strikes 
are reported.
    In order to better account for the accidental nature of vessel 
strikes to large whales in general and the potential risk from U.S. 
Navy vessel movement within the HSTT Study Area during the remaining 
period of the HSTT rule in particular, the Navy requested the HSTT rule 
be modified to authorize additional incidental takes by vessel strike 
based on probabilities derived from a Poisson distribution using vessel 
strike data between 2009-2021 in the HSTT Study Area (the time period 
from when current mitigations were instituted until the Navy conducted 
the analysis for the 2022 Navy application), as well as historical at-
sea days in the HSTT Study Area from 2009-2015 and estimated at-sea 
days for the period from 2016 to 2025 covered by the current 
regulations. This distribution predicted the probabilities of a 
specific number of strikes (n = 0, 1, 2, etc.) over the remaining 
period of the regulations at the time of the Navy's analysis (2022-
2025).
    The Navy used the two fin whale strikes (2009) and two unidentified 
large whale strikes (2021) in their calculations to determine the 
number of strikes likely to result from its activities over the 
remaining 3 years of the rule (2023-2025, although worldwide strike 
information from all Navy activities and other sources was used to 
inform the species that may be struck). The Navy evaluated data 
beginning in 2009 as that was the start of the Navy's Marine Species 
Awareness Training and adoption of additional mitigation measures to 
address vessel strike, which will remain in place along with additional 
and modified mitigation measures during the 7 years of this rulemaking. 
From this analysis, the Navy concluded that there was a 27 percent 
chance that zero whales would be struck by Navy vessels over the 
remaining period of the rule (which, at the time that the application 
was submitted, was 4 years), and a 35, 23, and 10 percent chance that 
one, two, or three whales, respectively, would be struck over the 
remaining 4 years of the rule. Therefore, the Navy estimated that there 
was some probability that the Navy could strike, and take by serious 
injury or mortality, up to three large whales incidental to training 
and testing activities within the HSTT Study Area over what would have 
been the remaining 4 years of the current authorization, and the Navy 
requested authorization of two additional takes of large whales by 
serious injury or mortality by vessel strike, beyond the three takes 
authorized by the 2020 HSTT final rule (85 FR 41780, July 10, 2020).
    NMFS has since updated this analysis to reflect that an additional 
strike of an unidentified large whale occurred in May 2023 (either a 
fin whale or sei whale, as stated above) and that additional time has 
passed since the Navy submitted the 2022 Navy application. Based on 
further discussions with the Navy, NMFS has also updated the way it 
calculated at-sea days. This is a different manner of calculating at-
sea days for the purposes of the strike analysis rather than a change 
in Navy's activity levels. For 2010-2015, the at-sea days used in NMFS' 
calculation reflected historic at-sea days in the HSTT action area 
based on positional vessel data records (Mintz, 2016). While the actual 
annual at-sea days from 2016-present are currently classified, NMFS' 
updated calculation reflects an extrapolation of the 2010-2015 at-sea 
days (using the formula y = -64x+131555) to estimate the number of at-
sea days in 2016 (Navy, 2022). The number of at-sea days derived for 
2016 was 2,056 at-sea days, which reflects the downward trend in HSTT 
vessel activity from 2010-2015. Since we do not have sufficient 
information to say whether or not this downward trend continued for the 
years 2017-2023, we conservatively estimate the average over these 
years was the same as the 2016 extrapolated value of 2,056 at-sea days. 
This analysis only included at-sea days for Navy warships greater than 
65 feet (i.e., destroyers are the smallest ship class included). Navy 
vessels smaller than 65 feet have never reported a whale strike in the 
Pacific, and therefore, we consider it unlikely that this would occur 
in the remaining period of the regulations.

       Table 4--HSTT 2009 Through Mid-2023 At-Sea Days Used for the Vessel Strike Probability Calculation
----------------------------------------------------------------------------------------------------------------
                     Year                         At-Sea days                      Derivation
----------------------------------------------------------------------------------------------------------------
2009..........................................           4,233  Estimated average based on 2010-2015 data.
2010..........................................           5,207  Based on positional vessel data.
2011..........................................           4,483  Based on positional vessel data.
2012..........................................           4,081  Based on positional vessel data.
2013..........................................           4,041  Based on positional vessel data.
2014..........................................           4,272  Based on positional vessel data.
2015..........................................           3,311  Based on positional vessel data.
2016..........................................           2,056  Extrapolated from 2010-2015 regression.
2017..........................................           2,056  Extrapolated from 2010-2015 regression.
2018..........................................           2,056  Extrapolated from 2010-2015 regression.
2019..........................................           2,056  Extrapolated from 2010-2015 regression.
2020..........................................           2,056  Extrapolated from 2010-2015 regression.
2021..........................................           2,056  Extrapolated from 2010-2015 regression.
2022..........................................           2,056  Extrapolated from 2010-2015 regression.
2023 (first half of year).....................           1,028  Extrapolated from 2010-2015 regression, then
                                                                 reduced by half.
2009- Mid-2023 total..........................          45,048  ................................................
----------------------------------------------------------------------------------------------------------------

    NMFS then used the number of past Navy vessel strikes and the at-
sea days to calculate a vessel strike rate for 2009 through mid-2023. 
The estimated total number of Navy at-sea days (for vessels greater 
than 65 feet) for 2009 through mid-2023 was 45,048 days. Dividing the 
five known strikes during that period by the at-sea days (i.e., 5 
strikes/45,048 at-sea days) results in a strike rate of 0.000111 
strikes per day.
    As described above, NMFS conservatively assumed that the average 
number of at-sea days from mid-2023 through 2025 (the remaining period 
of the regulations at the time that the analysis was conducted) will be 
the same as the 2016 extrapolated value of 2,056. Therefore, the 
estimated at-sea days within the action area for the period from mid-
2023 through 2025 is 5,140 days. NMFS multiplied the historic daily 
strike rate by the estimated at-sea days from mid-2023

[[Page 4978]]

through 2025 (0.000111 strikes per day x 5,140 days) to estimate the 
number of whale strikes anticipated during that period. This 
calculation predicts an estimated 0.57 strikes over the remaining 2.5 
years of the regulations at the time the analysis was conducted (mid-
2023 through 2025).
    As explained above, according to the U.S. Navy, the May 2021 vessel 
strike of two fin whales by a Royal Australian Navy vessel did not 
occur while that vessel was participating in a U.S. Navy-led training 
exercise, and the strike of those two fin whales is not included in the 
estimated take by vessel strike calculation. Instead, as noted below, 
NMFS considered the 2021 vessel strike by the Royal Australian Navy 
along with other strike information when determining which species 
could be among the estimated large whales struck.
    NMFS used a Poisson distribution to derive the probabilities of a 
specific number of strikes (n=0, 1, 2, etc.) from mid-2023 through 
2025, given the estimated 0.57 strikes during that period. NMFS' 
probability analysis concluded that there is a 57 percent chance that 
zero whales would be struck by U.S. Navy vessels from mid-2023 through 
2025, and a 32, 9, and 2 percent chance that one, two, or three whales, 
respectively, would be struck over that period. Further, there is an 
estimated 11 percent chance that the Navy would strike more than one 
large whale from mid-2023 through 2025. We have assessed these 
probabilities and determined that the strike of up to two large whales 
could occur over the remaining duration of the regulations, for a total 
of five takes by serious injury or mortality of large whales by vessel 
strike total over the 7-year duration of the regulations (three takes 
authorized in the 2020 HSTT final rule (85 FR 41780, July 10, 2020) 
which have occurred, plus two additional takes).
    In addition to the reasons listed above that make it unlikely that 
the Navy will hit a large whale (more maneuverable ships, larger crew, 
etc.), vessel strike of dolphins, small whales, porpoises, and 
pinnipeds is considered very unlikely. Dating back more than 20 years 
and for as long as it has kept records, the Navy has no records of any 
pinnipeds being struck by a vessel as a result of Navy activities. Over 
the same time period, NMFS and the Navy have only one record of a 
dolphin, porpoise, or small whale being struck by a vessel as a result 
of Navy activities. A dolphin was accidentally struck by a Navy small 
boat in fall 2021 in Saint Andrew's Pass, Florida. The smaller size and 
maneuverability of dolphins, small whales, and pinnipeds generally make 
such strikes very unlikely. Other than this one reported strike of a 
dolphin in 2021, NMFS has never received any reports from other LOA or 
Incidental Harassment Authorization holders indicating that these 
species have been struck by vessels. In addition, worldwide vessel 
strike records show little evidence of strikes of these groups from the 
shipping sector and larger vessels, and the majority of the Navy's 
activities involving faster-moving vessels (that could be considered 
more likely to hit a marine mammal) are located in offshore areas where 
smaller delphinid, porpoise, and pinniped densities are lower. Based on 
this information, NMFS concurs with the Navy's assessment and 
recognizes the potential for (and is authorizing) incidental take by 
vessel strike of large whales only (i.e., no dolphins, small whales, 
porpoises, or pinnipeds) over the course of the 7-year regulations from 
training and testing activities as discussed below.
    Next, after determining that take of up to five large whales could 
occur, NMFS considered which species could be among the five large 
whales struck. As noted in the 2018 HSTT proposed and final rules, the 
2019 HSTT proposed rule, 2020 HSTT final rule, and 2023 HSTT proposed 
rule, in the 2017 Navy rulemaking/LOA application, the Navy initially 
considered a weight of evidence approach that considered relative 
abundance, historical strike data over many years, and the overlap of 
Navy activities with the stock distribution in their request. NMFS 
updated this analysis to consider several factors, in addition to the 
overlap of Navy activities with stock distribution: (1) The relative 
likelihood of striking one stock versus another based on available 
strike data from all vessel types as denoted in the Carretta et al. 
(2021; referenced in the Pacific SARs), the Pacific and Alaska SARs 
(Carretta et al. 2024 and Young et al. 2024), and unpublished NMFS 
vessel strike data for 2019-2021; and (2) whether the Navy has ever 
struck an individual from a particular species or stock in the HSTT 
Study Area, and if so, how many times. (Note that since publication of 
the 2023 HSTT proposed rule, Carretta et al. (2023), which includes 
vessel strike data through 2021 has published, but NMFS included this 
data in its analysis through the unpublished NMFS vessel strike data 
for 2019-2021, referenced above). NMFS did not consider relative 
abundance, as was considered in previous analyses, given that the 
relative abundance of a stock does not necessarily inform its 
occurrence in a specific area. Further, NMFS did not consider the 
historical strike data from older years (prior to 2015), given that 
more recent data is more relevant to determining occurrence of, and 
strike risk to, various stocks. NMFS updated the analysis with NMFS' 
vessel strike probability analysis for the remaining period of the rule 
(2.5 years at the time of the analysis) and included new/updated vessel 
strike data from the SARs and NMFS records for California and Hawaii.
    To address number (1) above, for SOCAL, NMFS compiled information 
from Carretta et al. (2021) and unpublished NMFS vessel strike data for 
2020-2021 (since published in Caretta et al. (2023)) for California on 
known annual rates of large whale serious injury or mortality from 
vessel collisions (this data includes the strike of two fin whales by 
the Royal Australian Navy in 2021, but does not include Navy strikes in 
2021 and 2023 because the species struck is not known). Use of Carretta 
et al. (2021) rather than the Pacific SAR allows NMFS to separate 
strikes that occurred in California from strikes to the same stocks 
that occurred in other locations. For the HRC, NMFS compiled 
information from the Pacific and Alaska SARs and unpublished NMFS 
vessel strike data for 2019-2021 for Hawaii on known annual rates of 
large whale serious injury or mortality from vessel collisions. The 
annual rates of large whale serious injury or mortality from vessel 
collisions from those sources help inform the relative susceptibility 
of large whale species to vessel strike in SOCAL and the HRC; 
therefore, we considered only reported strikes where the species struck 
was identified with sufficient certainty (i.e., ``known strikes''). 
Additionally, the M/SI in the 2023 SAR considers modeled takes for 
some, but not most species and stocks (i.e., M/SI for humpback whale 
includes modeled takes from Rockwood et al. (2017)). Using known strike 
data for all species and stocks allows us to consider-like metrics for 
this comparative analysis. (Note we rely on the M/SI estimates from the 
2023 SAR (or draft 2023 SAR, where relevant) in our negligible impact 
analysis. We also consider modeled takes of species from Rockwood et 
al. (2017) in table 7). We summed the annual rates of serious injury or 
mortality from vessel collisions in California and Hawaii as calculated 
above and then divided each species' annual rate by this sum to get the 
proportion of strikes for each species/stock (table 5).

[[Page 4979]]



   Table 5--Annual Rates of Serious Injury and Mortality From Vessel Strike and Percentage of Total Strikes by
                                          Species in SOCAL and the HRC
----------------------------------------------------------------------------------------------------------------
                                                                 SOCAL annual     HRC annual      Percentage of
      ESA status              Species              Stock         known strikes   known strikes    total annual
                                                                  (2015-2021)     (2015-2021)        strikes
----------------------------------------------------------------------------------------------------------------
Listed................  Blue whale........  Central North       ..............               0               0.0
                                             Pacific.
                                            Eastern North                 0.57  ..............               6.5
                                             Pacific.
                        Fin whale \a\.....  California,                   1.57  ..............              17.8
                                             Oregon, &
                                             Washington.
                                            Hawaiian..........  ..............               0               0.0
                        Humpback whale....  Central America/             1 \b\  ..............              11.3
                                             Southern Mexico-
                                             CA/OR/WA (Central
                                             America DPS).
                                            Mainland Mexico-
                                             CA/OR/WA (Mexico
                                             DPS).
                        Sei whale.........  Eastern North                 0.14  ..............               1.6
                                             Pacific.
                                            Hawaiian..........  ..............               0               0.0
                        Gray whale........  Western North                    0  ..............               0.0
                                             Pacific.
                        Sperm whale.......  California,                      0  ..............               0.0
                                             Oregon, &
                                             Washington.
                                            Hawaiian..........  ..............               0               0.0
Not listed............  Gray whale........  Eastern North                 2.14  ..............              24.3
                                             Pacific.
                        Bryde's whale.....  ETP stock.........               0  ..............               0.0
                                            Hawaiian..........  ..............               0               0.0
                        Minke whale.......  CA/OR/WA..........               0  ..............               0.0
                                            Hawaii............  ..............               0               0.0
                        Humpback whale....  Hawaii (Hawaii      ..............             3.4              38.5
                                             DPS).
                       -----------------------------------------------------------------------------------------
    Total.............  ..................  ..................               8.82               ................
----------------------------------------------------------------------------------------------------------------
\a\ This includes the two fin whales struck by the Royal Australian Navy in May 2021.
\b\ This strike occurred to an individual of the CA/OR/WA stock under the previous stock structure. As such, in
  its analysis, NMFS assumed that this strike could have been of either stock.

    To inform the likelihood of striking a particular species of large 
whale, we multiplied the percent of total annual strikes for a given 
species in table 5, by the total percent likelihood of striking at 
least one whale during the remaining period of the rule (2023-2025 at 
the time of the analysis; i.e., 43 percent, as described by the 
probability analysis above). We also calculated the percent likelihood 
of striking a particular species of large whale twice during the 
remaining period of the rule by squaring the value estimated for the 
probability of striking a particular species of whale once (i.e., to 
calculate the probability of an event occurring twice, multiply the 
probability of the first event by the second). The results of these 
calculations are reflected in the last two columns of table 6. We note 
that these probabilities vary from year to year as the average annual 
mortality changes depending on the specific range of time considered; 
however, over the years and through updated data in the SARs and 
unpublished NMFS records, stocks tend to consistently maintain a 
relatively higher or relatively lower likelihood of being struck.

  Table 6--Percent Likelihood of Striking Each Stock One or Two Times Over 2.5 Years and Total Known U.S. Navy
                                         Strikes in the HSTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                                      Percent         Percent
                                                            Total known U.S Navy   likelihood of   likelihood of
              Species                       Stock          strikes in HSTT study   1 strike over  2 strikes over
                                                                    area             2.5 years       2.5 years
----------------------------------------------------------------------------------------------------------------
Blue whale........................  Central North Pacific  0....................            0.00            0.00
                                    Eastern North Pacific  1 in SOCAL (2004)....            2.81            0.08
Fin whale.........................  CA/OR/WA.............  3 in SOCAL (2009,            7.74 \b\        0.60 \b\
                                                            2023 \a\).
                                    Hawaiian.............  0....................            0.00            0.00
Humpback whale....................  Central America/       0....................            4.93            0.24
                                     Southern Mexico- CA/
                                     OR/WA (Central
                                     America DPS).
                                    Mainland Mexico- CA/
                                     OR/WA (Mexico DPS).
Sei whale.........................  Eastern North Pacific  1 in SOCAL (2023 \a\)            0.69            0.00
                                    Hawaiian.............  0....................            0.00            0.00
Gray whale........................  Western North Pacific  0....................            0.00            0.00
Sperm whale.......................  CA/OR/WA.............  0.00.................            0.00
                                    Hawaiian.............  1 in HRC (2007)......            0.00            0.00
Gray whale........................  Eastern North Pacific  3 in SOCAL (1993,               10.55            1.11
                                                            1998).
Bryde's whale.....................  ETP stock............  0....................            0.00            0.00
                                    Hawaiian.............  0....................            0.00            0.00
Minke whale.......................  CA/OR/WA.............  0....................            0.00            0.00
                                    Hawaii...............  0....................            0.00            0.00

[[Page 4980]]

 
Humpback whale....................  Hawaii (Hawaii DPS)..  2 in HRC (2003)......           16.76            2.81
----------------------------------------------------------------------------------------------------------------
\a\ Based on available photos and video, NMFS and the Navy have determined the May 2023 strike was of either a
  fin whale or sei whale. In the analysis herein, NMFS has assumed that this strike could have been of either
  species, and has therefore, accounted for it in both the fin whale and sei whale strike totals. Given that we
  are unable to identify the species of the whales struck by the U.S. Navy in 2021, NMFS did not include the two
  2021 strikes in this part of the analysis.
\b\ This includes the two fin whales struck by the Royal Australian Navy in May 2021.

    The percent likelihood calculated as described above are then 
considered in combination with the information indicating the known 
species that the Navy has hit in the HSTT Study Area since 1991 (since 
they started tracking consistently; table 6). We note that for the 
lethal take of species specifically denoted in table 7 below, 47 
percent of those struck by the Navy (8 of 17 in the Pacific) remained 
unidentified (including the May 2023 strike, which as stated above, 
NMFS and the Navy have determined was of either a fin whale or sei 
whale). However, given the information on known stocks struck, the 
analysis below remains appropriate. We also note that Rockwood et al. 
(2017) modeled the likelihood of vessel strike of blue whales, fin 
whales, and humpback whales on the U.S. West Coast (discussed in more 
detail in the Serious Injury or Mortality subsection of the Analysis 
and Negligible Impact Determination section), and those numbers help 
inform the relative likelihood that the Navy could hit those stocks.
    For each indicated stock, table 7 includes the percent likelihood 
of striking an individual whale from a particular stock during the 
remaining 2.5 years of the rule once based on SAR data, Carretta et al. 
(2021), and unpublished NMFS vessel strike data from 2019-2021 for 
Hawaii; total strikes from Navy vessels in the HSTT Study Area, and 
modeled vessel strikes from Rockwood et al. (2017). The last column 
indicates the authorized annual mortality.

              Table 7--Summary of Factors Considered in Determining the Number of Individuals in Each Stock Potentially Struck by a Vessel
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               Percent                             Rockwood et     Annual
                                                                              likelihood    Total known U.S Navy     al. 2017    authorized     Annual
       ESA status                  Species                   Stock              of one     strikes in HSTT study     modeled     take from    authorized
                                                                             strike over     area  (1993-2009)        vessel     2020 HSTT       take
                                                                              2.5 years                            strikes \1\   final rule
--------------------------------------------------------------------------------------------------------------------------------------------------------
Listed..................  Blue whale..............  Central North Pacific..         0.00  0......................  ...........  ...........            0
                                                    Eastern North Pacific..         2.81  1 in SOCAL (2004)......           18         0.14         0.14
                          Fin whale...............  CA/OR/WA...............     7.74 \2\  3 in SOCAL (2009, 2023            43         0.29         0.57
                                                                                           \3\).
                                                    Hawaii.................         0.00  0......................  ...........  ...........            0
                          Humpback whale \4\......  Central America/                4.93  0......................           22         0.14            0
                                                     Southern Mexico- CA/OR/
                                                     WA (Central America
                                                     DPS).
                                                    Mainland Mexico-CA/OR/   ...........  .......................  ...........  ...........         0.14
                                                     WA (Mexico DPS).
                          Sei whale...............  Eastern North Pacific..         0.69  1 in SOCAL(2023) \3\...  ...........  ...........         0.14
                                                    Hawaii.................         0.00  0......................  ...........  ...........            0
                          Gray whale..............  Western North Pacific..         0.00  0......................  ...........  ...........            0
                          Sperm whale.............  CA/OR/WA...............         0.00  0......................  ...........  ...........            0
                                                    Hawaii.................         0.00  1 in HRC (2007)........  ...........         0.14            0
Not listed..............  Gray whale..............  Eastern North Pacific..        10.55  3 in SOCAL (1993, 1998)  ...........         0.29         0.57
                          Bryde's whale...........  Eastern Tropical                0.00  0......................  ...........  ...........            0
                                                     Pacific.
                                                    Hawaii.................         0.00  0......................  ...........  ...........            0
                          Minke whale.............  CA/OR/WA...............         0.00  0......................  ...........  ...........            0
                                                    Hawaii.................         0.00  0......................  ...........  ...........            0
                          Humpback whale..........  Hawaii (Hawaii DPS) \5\        16.76  2 in HRC (2003)........  ...........         0.29         0.29
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Rockwood et al. modeled likely annual vessel strikes off the West Coast for these three species only.
\2\ This includes the two fin whales struck by the Royal Australian Navy in May 2021.
\3\ Based on available photos and video, NMFS and the Navy have determined the May 2023 strike was of either a fin whale or sei whale. In the analysis
  herein, NMFS has assumed that this strike could have been of either species, and has therefore, accounted for it in both the fin whale and sei whale
  strike totals.
\4\ In the 2020 HSTT final rule, take of humpback whale by serious injury and mortality by vessel strike in SOCAL was attributed to the former CA/OR/WA
  stock and the Mexico DPS. Text explains why takes in SOCAL come from the Mexico DPS, and therefore the Mainland Mexico-CA/OR/WA stock.
\5\ The 2023 final SAR reports vessel strike data for the Hawaii stock of humpback whales in Alaska, Washington, and Hawaii. Only vessel strike data
  from Hawaii was incorporated into our analysis as Alaska and Washington are outside of the HSTT Study Area.

    Accordingly, stocks that have no record of ever having been struck 
by any vessel are considered to have a zero percent likelihood of being 
struck by the Navy in the 7-year period of the rule. Stocks that have 
never been struck by the Navy, have rarely been struck by other 
vessels, and have a low percent likelihood based on the historical 
vessel strike calculation are also considered to have a zero percent 
likelihood to be struck by the Navy during the 7-year rule. We note 
that while vessel strike records have not differentiated between 
Eastern North Pacific and Western North Pacific gray whales, given 
their small population size and the comparative rarity with which 
individuals from the Western North Pacific stock are detected off the 
U.S. West Coast, it is highly unlikely that

[[Page 4981]]

they would be encountered, much less struck. This rules out all but 
seven stocks. Further, it is unlikely that the Hawaii stock of sperm 
whale would be struck given the zero percent likelihood of striking a 
sperm whale as indicated by the quantitative analysis above, the fact 
that the last U.S. Navy strike of a Hawaii stock sperm whale was in 
2007, before the mitigation updates discussed above, and that, with the 
exception of humpback whales, vessel strikes (both military and non-
military) of other large whale species in the HRC are extremely rare 
events (Carretta 2021b; Carretta 2022). (The 2020 HSTT final rule 
authorized one take (0.14 annual take) by mortality of the Hawaii stock 
of sperm whale.)
    As stated previously, based on available photos and video of the 
whale struck by the U.S. Navy in Southern California in 2023, NMFS and 
the Navy have determined this whale was either a fin whale or sei 
whale. While the species of the two whales struck by the U.S. Navy in 
2021 are unknown, given the following factors, NMFS expects these 
strikes may have been CA/OR/WA fin whales or Eastern North Pacific 
(ENP) gray whales, or some combination of these two stocks. These 
species have the highest annual rates of M/SI from vessel collision in 
California (1.57, 2.14, respectively, as noted above; which is 
approximately one and a half to two times higher than the species with 
the next highest strike rate, humpback whale, and approximately two to 
four times higher than the strike rate of blue whale). Additionally, 
gray whale and fin whale have the most recorded vessel strike incidents 
by military vessels in SOCAL and are the only stocks known to have been 
hit more than one time by naval vessels in the SOCAL portion of the 
HSTT Study Area (three gray whale strikes by the U.S. Navy (1993, 
1998), two or three fin whale strikes by the U.S. Navy (2009, 
potentially 2023), and two fin whale strikes by the Royal Australian 
Navy (2021)). Further, accounting for undocumented vessel strikes, 
Rockwood et al. (2021) estimated that in their study area off Southern 
California from 2012-2018, on average 8.9 blue, 4.6 humpback, and 9.7 
fin whales were killed by civilian vessel strikes from June to November 
each year. In addition, they estimated that, on average, 5.7 humpback 
whales were killed by civilian vessel strike from January-April per 
year (Rockwood et al. 2021). For fin whales in particular, model-
predicted densities of large whales in the Southern California Bight 
from May to July 2021 (the time period during which the 2021 strikes of 
two unidentified whales by the U.S. Navy occurred) estimated fin whale 
abundance as being nearly an order of magnitude higher than either blue 
or humpback whale abundance during this time period (Becker et al. 
2020; Zickel et al. 2021). Ship-whale encounter models for the U.S. 
West Coast Exclusive Economic Zone also indicated that vessel strike 
mortality estimates for fin whales were significantly higher than for 
blue whales and humpback whales (Rockwood et al. 2017). The 
comparatively higher modeled vessel strike rates for fin whales result 
from both the larger population as well as the more offshore 
distribution that overlaps significantly with several major shipping 
routes for a much greater spatial extent (Rockwood et al. 2017). Based 
on 1,243 visual boat-based sightings of 2,638 fin whales from 1991-
2011, Calambokidis et al. (2015) found fin whale concentration areas 
included the San Clemente Basin where the 2021 Navy vessel strikes 
occurred (Tanner and Cortez Banks area and the shelf edge west of San 
Nicolas Island were also reported as fin whale concentration areas). 
There are two different populations of fin whales that occur in the 
Southern California Bight: a seasonal population, and a population that 
occurs year-round with offshore/inshore movements (Campbell et al. 
2015; Falcone et al. 2022). This would likely make fin whales more 
susceptible to vessel strike year-round, as compared to other large 
whale species that may occur seasonally within SOCAL. Based on all of 
these factors, there is a reasonable likelihood that the CA/OR/WA stock 
of fin whales or ENP stock of gray whales could be struck twice during 
the remaining period of the rule. Therefore, we find that, of the five 
total takes by serious injury or mortality by vessel strike of large 
whales authorized over the course of the 7-year rule, up to four of 
those takes could be of the CA/OR/WA stock of fin whale or the ENP 
stock of gray whale given that the two strikes of unidentified large 
whales in 2021 could have been of either stock. Further, consistent 
with the 2020 HSTT final rule, we expect that, of the five total takes 
by serious injury or mortality by vessel strike of large whales 
authorized, up to two of those takes could occur in Hawaii, and 
therefore be of individuals of the Hawaii stock of humpback whale.
    Based on the information summarized in table 7 and the fact that 
there is the potential for up to two large whales to be struck over the 
remaining period of the rule (five strikes over the full 7-year rule 
period), one individual from the Eastern North Pacific stock of blue 
whale, Mainland Mexico-CA/OR/WA stock of humpback whale, or Eastern 
North Pacific stock of sei whale could be among the two whales struck 
during the remaining effective period of the regulations (2023-2025 at 
the time of the analysis). The total strikes of Eastern North Pacific 
blue whales and the percent likelihood of striking one based on the 
historic strike calculation above can both be considered moderate 
compared to other stocks, and the Navy struck a blue whale in 2004 
(based on the historic strike calculation, the likelihood of striking 
two blue whales is well below one percent (table 6)). Therefore, we 
consider it reasonably likely that the Navy could strike one individual 
over the course of the 7-year rule, and given that we do not expect 
that the 2023 strike nor either of the 2021 U.S. Navy strikes of 
unidentified large whales were blue whales, we expect that this strike 
could occur during the remaining period of the rule. The total strikes 
of Eastern North Pacific sei whales are low compared to other stocks, 
but NMFS and the Navy think it is possible that the Navy may have 
struck a sei whale in SOCAL in 2023. Therefore, we consider it 
reasonably likely that the Navy could strike a sei whale over the 
remaining period of the rule. The Navy has not hit a humpback whale in 
the SOCAL portion of the HSTT Study Area. However, in 2016 a U.S. Coast 
Guard vessel participating in a Navy event struck a humpback whale in 
Hood Canal, and as a species, humpbacks have a moderate to high number 
of total strikes and percent likelihood of being struck. Although the 
likelihood of Central America/Southern Mexico- CA/OR/WA (Central 
America DPS) or Mainland Mexico-CA/OR/WA (Mexico DPS) humpback whales 
being struck by any vessel type is moderate to high relative to other 
stocks, the distribution of the Mexico DPS versus the Central America 
DPS, as well as the distribution of overall vessel strikes inside 
versus outside of the SOCAL area (the majority are outside), supports 
the reasonable likelihood that the Navy could strike one individual 
humpback whale from the Mainland Mexico-CA/OR/WA stock (Mexico DPS) 
over the 7-year duration of the rule, as described below.
    Regarding the likelihood of striking a humpback whale from a 
particular DPS, we evaluated the relative abundance of each of these 
DPS in California waters. Curtis et al. (2022) estimated the abundance 
of the Central America DPS to be 1,496 whales. From Wade et al. (2017), 
about 93 percent (or 1,391

[[Page 4982]]

whales) of these humpbacks that winter in Central America will move to 
Oregon/California in the summer months. While there is currently no 
abundance estimate for the Mexico DPS, an estimated 3,477 whales from 
the Mexico DPS feed off the U.S. West Coast (Calambokidis and Barlow 
2020; Curtis 2022). Based on this information, we estimate that 
approximately 30 percent of the humpback whales off the coast of 
California may be from the Central America DPS with the remaining 70 
percent expected to be from the Mexico DPS. Therefore, we anticipate 
that if a Navy vessel strike of a humpback whale were to occur within 
SOCAL, it would likely be from the Mexico DPS. Last, Rockwood et al. 
(2017) supports a relative likelihood of 1:1:2 for striking blue 
whales, humpback whales, and fin whales off the U.S West Coast (though 
as noted above, more recent data suggests that the relative likelihood 
of striking a fin whale is higher and suggests that the two 2021 U.S. 
Navy vessel strikes of unidentified large whales may have been fin 
whales), which, in consideration of more recent data also supports the 
authorized take included in this rule, which is 1, 1, and 4, 
respectively over the 7-year period. For these reasons, one lethal take 
of a Mainland Mexico-CA/OR/WA humpback whale (Mexico DPS) could occur 
and is authorized.
    For Hawaii stocks, given that all known vessel strikes between 2015 
and 2021 were of humpback whales, we anticipate that any vessel strike 
of a large whale in Hawaii would be of the Hawaii stock of humpback 
whale. Given that this stock has the highest percentage of total annual 
strikes (38.5 percent) and a 2.81 percent chance of being struck twice 
over the remaining period of the rule (more than twice that of the 
species with the next highest percentage, gray whale), NMFS authorizes 
two lethal takes of Hawaii humpback whales.
    As described above, the Navy's analysis suggests and NMFS' analysis 
concurs that the likelihood of vessel strikes to the stocks below is 
discountable due to the stocks' relatively low occurrence in the HSTT 
Study Area, particularly in core HSTT training and testing subareas, 
and the fact that the stocks have not been struck by the Navy and are 
rarely, if ever, recorded struck by other vessels. Therefore, NMFS is 
not authorizing lethal take for the following stocks: Blue whale 
(Central North Pacific stock), Bryde's whale (Eastern Tropical Pacific 
stock and Hawaii stock), fin whale (Hawaii stock), gray whale (Western 
North Pacific stock), humpback whale (Central America/Southern Mexico-
CA/OR/WA stock, Central America DPS), minke whale (CA/OR/WA stock and 
Hawaii stock), sei whale (Hawaii stock), and sperm whale (CA/OR/WA 
stock and Hawaii stock).
    Also of note, while information on past Navy vessel strikes can 
serve as a reasonable indicator of future vessel strike risk, future 
conditions may differ from the past in ways that could influence the 
likelihood of a large whale vessel strike occurring. In general, the 
magnitude of vessel strike risk may be increasing over time as many 
whale populations are gradually recovering from centuries of commercial 
whaling (Redfern et al. 2020). Increased vessel strike risk off 
California in recent decades has been associated with increases in the 
abundance of fin and humpback whale populations in the North Pacific 
(Redfern et al. 2020). It has also been suggested that the blue whale 
population in the Eastern North Pacific, inclusive of the SOCAL portion 
of the HSTT Study Area, is at carrying capacity and recovered to pre-
whaling levels (Monnahan et al. 2014). In addition, the magnitude of 
risk may also be affected by shifts in whale distributions over time in 
response to environmental factors including climate change, marine 
heatwaves, and associated changes in prey distribution.
    Historically, military vessel strikes of large whales within the 
HSTT Study Area have been rare events with only seven such strikes 
occurring over the past 14 years, five U.S. Navy strikes, and two Royal 
Australian Navy strikes. However, the fact that four of these strikes 
occurred within a 3-month period (May-July) in 2021, and two occurred 
within a 4-month period (February-May) in 2009, suggests that military 
vessel strikes in SOCAL can be both highly episodic and clustered. The 
four large whale strikes in 2021 (two strikes of unidentified large 
whales by the U.S. Navy and two fin whale strikes by the Royal 
Australian Navy) appear to be outliers in the time series of military 
vessel strikes in SOCAL for that period. However, particularly in 
consideration of the 2023 U.S. Navy strike, these strikes could also 
represent an early indicator of an increased military vessel strike 
risk within SOCAL based on the factors discussed above. Results from a 
survey of whale watching vessel operators and crew in Southern 
California, combined with remote sensing data in the area, suggest that 
the number of large whales may have been greater in May through July of 
2021 compared with previous years in certain high military vessel 
traffic and ``core'' use HSTT areas off southern California, 
particularly farther offshore as well as closer to shore off San Diego 
Bay (Zickel MJ et al. 2021).
    In conclusion, while take by vessel strike across any given year is 
sporadic, based on the information and analysis above, including 
consideration of the 2021 and 2023 strikes by the U.S. Navy, NMFS 
anticipates no more than five takes of large whales by M/SI could occur 
over the 7-year period of the rule. Of those five whales over the 7-
years, no more than four may come from the following stocks: gray whale 
(Eastern North Pacific stock) and fin whale (CA/OR/WA stock). No more 
than two may come from the Hawaii stock of humpback whales. No more 
than one may come from the following stocks: blue whale (Eastern North 
Pacific stock), sei whale (Eastern North Pacific), and humpback whale 
(Mexico-North Pacific stock or Mainland Mexico-CA/OR/WA, Mexico DPS). 
Accordingly, NMFS has evaluated under the negligible impact standard 
the M/SI of 0.14, 0.29, or 0.57 whales annually from each of these 
species or stocks (i.e., one, two, or four takes, respectively, divided 
by 7 years to get the annual number), along with the expected 
incidental takes by harassment.
Explosives
    The Navy's model and quantitative analysis process used for the 
2018 HSTT FEIS/OEIS and in the Navy's 2017 and 2019 applications to 
estimate potential exposures of marine mammals to explosive stressors 
is detailed in the technical report titled Quantifying Acoustic Impacts 
on Marine Mammals and Sea Turtles: Methods and Analytical Approach for 
Phase III Training and Testing report (U.S. Department of the Navy, 
2018). Specifically, over the course of a modeled maximum year of 
training and testing, the Navy's model and quantitative analysis 
process estimates M/SI of two short-beaked common dolphin and one 
California sea lion as a result of exposure to explosive training and 
testing activities (please see section 6 of the 2017 Navy application 
where it is explained how maximum annual estimates are calculated). 
Over the 7[hyphen]year period of the 2020 HSTT regulations, M/SI of 8 
short-beaked common dolphins and 5 California sea lions (13 marine 
mammals in total) is estimated as a result of exposure to explosive 
training and testing activities. NMFS makes no changes to the 
authorization of take by M/SI as a result of explosive use as the Navy 
made no changes to its activities from that described in the 2018 HSTT 
final rule, and after reviewing all new information,

[[Page 4983]]

we find that our previous analyses remain applicable. Please refer to 
the 2018 HSTT final rule and 2020 HSTT final rule for additional 
information.

Mitigation Measures

    Under section 101(a)(5)(A) of the MMPA, NMFS must set forth the 
permissible methods of taking pursuant to the activity, and other means 
of effecting the least practicable adverse impact on the species or 
stock(s) and its habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance, and on the 
availability of the species or stock(s) for subsistence uses (``least 
practicable adverse impact''). NMFS does not have a regulatory 
definition for least practicable adverse impact. The 2004 NDAA amended 
the MMPA as it relates to military readiness activities and the 
incidental take authorization process such that a determination of 
``least practicable adverse impact'' shall include consideration of 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity. For the full 
discussion of how NMFS interprets least practicable adverse impact, 
including how it relates to the negligible-impact standard, see the 
Mitigation Measures section in the 2018 HSTT final rule.
    Section 101(a)(5)(A)(i)(II) requires NMFS to issue, in conjunction 
with its authorization, binding--and enforceable--restrictions (in the 
form of regulations) setting forth how the activity must be conducted, 
thus ensuring the activity has the ``least practicable adverse impact'' 
on the affected species or stocks. In situations where mitigation is 
specifically needed to reach a negligible impact determination, section 
101(a)(5)(A)(i)(II) also provides a mechanism for ensuring compliance 
with the ``negligible impact'' requirement. Finally, the least 
practicable adverse impact standard also requires consideration of 
measures for marine mammal habitat, with particular attention to 
rookeries, mating grounds, and other areas of similar significance, and 
for subsistence impacts, whereas the negligible impact standard is 
concerned solely with conclusions about the impact of an activity on 
annual rates of recruitment and survival.\1\ In evaluating what 
mitigation measures are appropriate, NMFS considers the potential 
impacts of the Specified Activities, the availability of measures to 
minimize those potential impacts, and the practicability of 
implementing those measures, as we describe below. This final rule 
includes all mitigation measures required by the 2020 HSTT final rule 
(though two have been modified in this final rule), and our discussion 
in that rule remains complete and accurate (including reference to the 
2018 HSTT final rule), except as described below.
---------------------------------------------------------------------------

    \1\ Outside of the military readiness context, mitigation may 
also be appropriate to ensure compliance with the ``small numbers'' 
language in MMPA sections 101(a)(5)(A) and (D).
---------------------------------------------------------------------------

Implementation of Least Practicable Adverse Impact Standard

    Our evaluation of potential mitigation measures includes 
consideration of two primary factors:
    (1) The manner in which, and the degree to which, implementation of 
the potential measure(s) is expected to reduce adverse impacts to 
marine mammal species or stocks, their habitat, and their availability 
for subsistence uses (where relevant). This analysis considers such 
things as the nature of the potential adverse impact (such as 
likelihood, scope, and range), the likelihood that the measure will be 
effective if implemented, and the likelihood of successful 
implementation; and
    (2) The practicability of the measure(s) for applicant 
implementation. Practicability of implementation may consider such 
things as cost, impact on activities, and, in the case of a military 
readiness activity, specifically considers personnel safety, 
practicality of implementation, and impact on the effectiveness of the 
military readiness activity.
    While the language of the least practicable adverse impact standard 
calls for minimizing impacts to affected species or stocks, we 
recognize that the reduction of impacts to those species or stocks 
accrues through the application of mitigation measures that limit 
impacts to individual animals. Accordingly, NMFS' analysis focuses on 
measures that are designed to avoid or minimize impacts on individual 
marine mammals that are likely to increase the probability or severity 
of population-level effects.
    While direct evidence of impacts to species or stocks from a 
specified activity is rarely available, and additional study is still 
needed to understand how specific disturbance events affect the fitness 
of individuals of certain species, there have been improvements in 
understanding the process by which disturbance effects are translated 
to the population. With recent scientific advancements (both marine 
mammal energetic research and the development of energetic frameworks), 
the relative likelihood or degree of impacts on species or stocks may 
often be inferred given a detailed understanding of the activity, the 
environment, and the affected species or stocks--and the best available 
science has been used here. This same information is used in the 
development of mitigation measures and helps us understand how 
mitigation measures contribute to lessening effects (or the risk 
thereof) to species or stocks. We also acknowledge that there is always 
the potential that new information, or a new recommendation could 
become available in the future and necessitate reevaluation of 
mitigation measures (which may be addressed through adaptive 
management) to see if further reductions of population impacts are 
possible and practicable.
    In the evaluation of specific measures, the details of the 
specified activity will necessarily inform each of the two primary 
factors discussed above (expected reduction of impacts and 
practicability), and are carefully considered to determine the types of 
mitigation that are appropriate under the least practicable adverse 
impact standard. Analysis of how a potential mitigation measure may 
reduce adverse impacts on a marine mammal stock or species, 
consideration of personnel safety, practicality of implementation, and 
consideration of the impact on effectiveness of military readiness 
activities are not issues that can be meaningfully evaluated through a 
yes/no lens. The manner in which, and the degree to which, 
implementation of a measure is expected to reduce impacts, as well as 
its practicability in terms of these considerations, can vary widely. 
For example, a time/area restriction could be of very high value for 
decreasing population-level impacts (e.g., avoiding disturbance of 
feeding females in an area of established biological importance) or it 
could be of lower value (e.g., decreased disturbance in an area of high 
productivity but of less firmly established biological importance). 
Regarding practicability, a measure might involve restrictions in an 
area or time that impede the Navy's ability to certify a strike group 
(higher impact on mission effectiveness), or it could mean delaying a 
small in-port training event by 30 minutes to avoid exposure of a 
marine mammal to injurious levels of sound (lower impact). A 
responsible evaluation of ``least practicable adverse impact'' will 
consider the factors along these realistic scales. Accordingly, the 
greater the likelihood that a measure will contribute to reducing the 
probability or severity of adverse impacts to the

[[Page 4984]]

species or stock or its habitat, the greater the weight that measure is 
given when considered in combination with practicability to determine 
the appropriateness of the mitigation measure, and vice versa. In the 
evaluation of specific measures, the details of the specified activity 
will necessarily inform each of the two primary factors discussed above 
(expected reduction of impacts and practicability), and will be 
carefully considered to determine the types of mitigation that are 
appropriate under the least practicable adverse impact standard. For 
more detail on how we apply these factors, see the discussion in the 
Mitigation Measures section of the 2018 HSTT final rule.
Assessment of Mitigation Measures for HSTT Rule
    NMFS fully reviewed the Navy's specified activities and the 
mitigation measures for the 2020 HSTT final rule and determined, with 
the addition of the new and modified measures discussed herein, and 
after consideration of the new information and studies described above, 
that the mitigation measures would result in the least practicable 
adverse impact on marine mammals (see the 2019 Navy application and the 
2018 HSTT final rule for detailed information on the Navy's mitigation 
measures, with the exception of the new and modified measures described 
herein). NMFS worked with the Navy in the development of the Navy's 
mitigation measures, which were informed by years of implementation and 
monitoring. A complete discussion of the Navy's evaluation process used 
to develop, assess, and select mitigation measures, which was informed 
by input from NMFS, can be found in chapter 5 (Mitigation) of the 2018 
HSTT FEIS/OEIS. The process described in chapter 5 (Mitigation) of the 
2018 HSTT FEIS/OEIS robustly supports NMFS' independent evaluation of 
whether the mitigation measures would meet the least practicable 
adverse impact standard. The Navy has implemented the mitigation 
measures under the 2020 HSTT regulations and will be required to 
continue implementation of the mitigation measures identified in this 
rulemaking for the full 7 years it covers to avoid or reduce potential 
impacts from acoustic, explosive, and physical disturbance and vessel 
strike stressors.
    The Navy also evaluated numerous measures in the 2018 HSTT FEIS/
OEIS that were not included in the 2017 Navy application, and NMFS 
independently reviewed and considered all new information, and 
continues to concur with Navy's analysis that their inclusion was not 
appropriate under the least practicable adverse impact standard. The 
Navy considered these additional potential mitigation measures in two 
groups. First, chapter 5 (Mitigation) of the 2018 HSTT FEIS/OEIS, in 
the Measures Considered but Eliminated section, includes an analysis of 
an array of different types of mitigation that have been recommended 
over the years by NGOs or the public, through scoping or public comment 
on environmental compliance documents. Appendix K (Geographic 
Mitigation Assessment) of the 2018 HSTT FEIS/OEIS includes an in-depth 
analysis of time/area restrictions that have been recommended over time 
or previously implemented as a result of litigation.
    Below, we summarize the mitigation measures (organized into 
procedural measures and mitigation areas) that NMFS has determined will 
ensure the least practicable adverse impact on all affected species and 
stocks and their habitat, including the specific considerations for 
military readiness activities, and including several measures that are 
new or modified since publication of the 2020 HSTT final rule.
    In its 2022 application, the Navy proposed no changes to the 
procedural or geographic mitigation measures in the 2020 HSTT final 
rule. NMFS reviewed new information potentially pertinent to mitigation 
of the Navy's training and testing activities. While Lookouts are 
essential to detecting the potential for and potentially avoiding a 
vessel strike of a marine mammal, NMFS and the Navy have always 
acknowledged that Lookouts cannot prevent all vessel strikes. The 
recent U.S. Navy and Royal Australian Navy vessel strikes appear to 
confirm this, as these strikes occurred when Lookouts were posted. As 
acknowledged above, these recent incidents may represent an early 
indicator of an increased military vessel strike risk within SOCAL. 
Recent reports appear to reflect the sporadic, episodic, or clustered 
nature of vessel strike or may reflect a trend of increased large whale 
presence in this area in the early summer months. NMFS and the Navy 
have discussed the circumstances of each of the recent strikes, 
including the Royal Australian Navy strike, and discussed ways of 
improving strike mitigation. In these further conversations, NMFS and 
the Navy developed several new and modified mitigation measures in 
comparison to those included in the 2020 HSTT final rule.
    For vessel movement, the 2020 HSTT final rule required that ``When 
underway Navy personnel must observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must maneuver 
to maintain distance.'' This measure has been updated to state that 
reducing speed may be an appropriate way to maneuver. The revised 
measure states that ``When underway, Navy personnel must observe the 
mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must maneuver (which may include reducing speed as the 
mission or circumstances allow) to maintain distance.'' Of note, 
between 2009 and 2021 (the most recent year for which data is 
available), U.S. Navy vessels in the SOCAL portion of the HSTT Study 
Area maneuvered 316 times to avoid large whales during MTEs. The years 
2017 and 2021 had the highest number of maneuvers (n=64 and n=82, 
respectively). In all years for which data is available (2009 to 2021), 
Navy cruisers and destroyers account for 51 to 100 percent of maneuvers 
during MTEs. With this modified measure, NMFS is emphasizing that Navy 
personnel should consider reducing speed (as mission or circumstances 
allow) when maneuvering to avoid marine mammals, though this modified 
measure does not require reduction of vessel speed for reasons 
explained in chapter 5 (Mitigation) of the 2018 HSTT FEIS/OEIS, in the 
Measures Considered but Eliminated section (i.e., requirements to 
reduce vessel speeds would have significant direct negative effects on 
mission effectiveness).
    This final rule also requires that Navy personnel must send alerts 
to Navy vessels of increased risk of strike following any reported Navy 
vessel strike in the HSTT Study Area.
    Further, the 2020 HSTT final rule included a requirement for Navy 
personnel to issue seasonal awareness notification messages to alert 
ships and aircraft to the possible presence of blue whales (June-
October), humpback whales (November-April), gray whales (November-
March), or fin whales (November-May). These messages assist in 
maintaining safety of navigation and in avoiding interactions with 
large whales during transits. Platforms must use the information from 
the awareness notification messages to assist their visual observation 
of applicable mitigation zones during training and testing activities 
and to aid in the implementation of procedural mitigation. This final 
rule requires the Navy to re-title the spring blue whale message 
(released in June) to a large whale awareness message inclusive of 
typical spring-summer large whales in southern California (mainly blue, 
fin,

[[Page 4985]]

and humpback whales). Furthermore, rather than tying the message 
release to a specific month, the message would be for a period based on 
predicted oceanographic conditions for a given year (e.g., May-
November, April-November, etc.). The Navy will also evaluate 
information obtained from NMFS' Southwest Fisheries Science Center 
scientists, recently published West Coast BIAs (Calambokedis et al. 
2024), and other oceanographic or predictive models for guiding message 
text descriptions of whale occurrence in Southern California. The 
improvement will emphasize that when a marine mammal is spotted, this 
may be an indicator that additional marine mammals are present and 
nearby, and increased vigilance and awareness of Navy personnel is 
warranted.
    This final rule also contains a new mitigation measure in which 
Navy personnel would issue real-time notifications to Navy vessels of 
large whale aggregations (four or more whales) within 1 nmi (1.9 km) of 
a Navy vessel in a select area of SOCAL (Of note, the four whales do 
not have to be the same species and do not have to be part of the same 
group (e.g., two whales of one species sighted at a distance off the 
port side at 500 yd (457.2 m) and two more whales of another species 
sighted off the starboard side at 500 yd (457.2 m) will be considered 
an aggregation under this measure)). This measure will apply to the 
area between 32-33 degrees North and 117.2-119.5 degrees West, which 
includes the locations where recent (2009, 2021, 2023) strikes 
occurred, and historic locations where strikes occurred when precise 
latitude and longitude were known.
    Of note, in order to improve mitigation effectiveness, in fall 2022 
the Navy made several changes to its Lookout training. The Navy revised 
its basic Lookout training materials to improve marine mammal awareness 
and spotting techniques through updates to the Marine Mammal chapter of 
the Navy's September 2022 Lookout Training Handbook. Further, the Navy 
integrated improved Lookout training into a new generation of a 
shipboard simulator at its recruit training center in the Great Lakes. 
This simulator enhances new sailor knowledge and skill under realistic 
training scenarios. Last, the Navy will evaluate future revisions to 
online or DVD Marine Species Awareness Training video training to 
emphasize that when a protected species is spotted, this may be an 
indicator that additional marine mammals are present and nearby, and 
the vessel should take this into consideration when transiting.
    In addition to Lookouts required under this rule, the Navy mandates 
the number of Lookouts on underway vessels per internal policy 
documents, including the Surface Ship NAVDORM. As described in the 
Standard Operating Procedures section, in 2021, NAVDORM policy changed 
to require three Lookouts on most classes of surface ship, including 
destroyers and cruisers. However, the Navy asserts that always 
including three Lookouts on these vessels in the future as a required 
mitigation measure is not practicable because lookout numbers are 
subject to change based on national security needs, including manning 
and staffing requirements. As such, although the Navy describes these 
additional Lookouts in its application under the mitigation section, 
NMFS has not considered the potential presence of two additional 
lookouts when considering Navy's mitigation effectiveness. Please see 
the Reporting section for additional detail on this requirement.
    With the exception of Oedekoven and Thomas (2022) described above, 
there is no new information that affects NMFS' assessment of the 
applicability or effectiveness of the measures included in the 2018 
HSTT final rule over the remainder of the 7-year period. As stated 
above in the Potential Effects of Specified Activities on Marine 
Mammals and Their Habitat section, while (Oedekoven and Thomas, 2022) 
suggests that detection of marine mammals is less certain than 
previously assumed at certain distances, model assumptions may still 
underestimate Lookout effectiveness in some cases. Additionally, 
maneuvering data summarized above demonstrates that Navy vessels are 
successfully maneuvering to avoid striking sighted marine mammals in 
most cases, despite the Oedekoven and Thomas (2022) results. Further, 
as described above, Navy and NMFS have developed modified or new 
mitigation in this final rule which are anticipated to further reduce 
the risk of vessel strike of large whales.
    In summary, and as described in more detail above regarding vessel 
strike, the Navy has agreed to procedural mitigation measures that will 
reduce the probability and/or severity of impacts expected to result 
from acute exposure to acoustic sources or explosives, vessel strike, 
and impacts to marine mammal habitat. Specifically, the Navy will use a 
combination of delayed starts, powerdowns, and shutdowns to minimize or 
avoid M/SI and minimize the likelihood or severity of PTS or other 
injury, and reduce instances of TTS or more severe behavioral 
disturbance caused by acoustic sources or explosives. The Navy will 
also implement multiple time/area restrictions (several of which were 
added in the 2018 HSTT final rule since the previous HSTT MMPA 
incidental take rule) that would reduce take of marine mammals in areas 
or at times where they are known to engage in important behaviors, such 
as feeding or calving, where the disruption of those behaviors would 
have a higher probability of resulting in impacts on reproduction or 
survival of individuals that could lead to population-level impacts. 
Table 8 provides the Navy's required procedural mitigation measures for 
environmental awareness and education and vessel movement as well as 
summaries of the Navy's procedural mitigation measures for other 
activities. Table 9 provides summaries of mitigation areas for the HSTT 
Study Area.
    NMFS and the Navy considered additional mitigation areas (beyond 
those already identified with associated measures to reduce impacts to 
marine mammals) to further protect marine mammals, including 
odontocetes with small or resident populations in the HSTT Study Area, 
and large whales with feeding, reproductive, and migratory BIAs in the 
HSTT Study Area. This includes consideration of new mitigation areas 
that could be based on newly identified BIAs in Hawaii (Kratofil et al. 
2023) and on the West Coast (Calambokidis et al. 2024). The HRC 
overlaps BIAs identified in Kratofil et al. (2023) for humpback whale, 
spinner dolphin, short-finned pilot whale, rough-toothed dolphin, pygmy 
killer whale, pantropical spotted dolphin, melon-headed whale, false 
killer whale, dwarf sperm whale, goose-beaked whale, common bottlenose 
dolphin, and Blainville's beaked whale. All of the BIAs that overlap 
the HRC are small and resident population BIAs, with the exception of 
the humpback whale reproductive BIA. SOCAL overlaps BIAs identified in 
Calambokidis et al. (2024) for blue whale (feeding area), fin whale 
(feeding area), and gray whale (migratory route).
    Additional restrictions in mitigation areas beyond those 
restrictions and areas included in the 2020 HSTT final rule (including 
mitigation to reduce vessel strike risk such as vessel speed 
restrictions, and in consideration of the newly identified BIAs 
(Kratofil et al. 2023 and Calambokidis et al. 2024)) is impracticable 
given overlap with critical Navy training areas in the HRC and SOCAL. 
However, many of the BIAs

[[Page 4986]]

identified in Kratofil et al. 2023 and Calambokidis et al. (2024) 
partially or fully overlap the mitigation areas included in the 2020 
HSTT final rule and this final rule and are aimed at reducing impacts 
to the same species for which Kratofil et al. 2023 and Calambokidis et 
al. (2024) identified BIAs. In the HRC, the existing mitigation areas 
are targeted and expected to reduce impacts to humpback whales, false 
killer whales, dwarf sperm whales, pygmy killer whales, short-finned 
pilot whales, melon-headed whales, bottlenose dolphins, spotted 
dolphins, spinner dolphins, rough-toothed dolphins, goose-beaked 
whales, and Blainville's beaked whales (i.e., all species for which 
Kratofil et al. (2023) identified BIAs). In SOCAL, the existing 
mitigation areas are aimed at reducing impacts to blue whales, fin 
whales, and gray whales (i.e., all species for which Calambokidis et 
al. (2024) identified BIAs). Further, as included in the 2023 HSTT 
proposed rule, this final rule requires that Navy personnel must issue 
real-time notifications to Navy vessels of large whale aggregations 
(four or more whales) within 1 nmi (1.9 km) of a Navy vessel in a 
select area of SOCAL, and that Navy personnel must send alerts to Navy 
vessels of increased risk of strike following any reported Navy vessel 
strike in the HSTT Study Area. Last, this final rule includes 
modification of two mitigation measures from the 2020 HSTT final rule 
(85 FR 41780; July 10, 2020) to further reduce the potential for vessel 
strike.

                Table 8--Summary of Procedural Mitigation
------------------------------------------------------------------------
                                    Mitigation zone sizes and other
     Stressor or activity                     requirements
------------------------------------------------------------------------
Environmental Awareness and     This mitigation applies to all
 Education.                     training and testing activities, as
                                applicable.
                                Mitigation Requirements:
                                  [cir] Appropriate Navy personnel
                                   (including civilian personnel)
                                   involved in mitigation and training
                                   or testing activity reporting under
                                   the specific activities must complete
                                   one or more modules of the U.S. Navy
                                   Afloat Environmental Compliance
                                   Training Series, as identified in
                                   their career path training plan.
                                   Modules include:
                                    [ssquf] Introduction to the U.S.
                                     Navy Afloat Environmental
                                     Compliance Training Series. The
                                     introductory module provides
                                     information on environmental laws
                                     (e.g., ESA, MMPA) and the
                                     corresponding responsibilities that
                                     are relevant to Navy training and
                                     testing activities. The material
                                     explains why environmental
                                     compliance is important in
                                     supporting the Navy's commitment to
                                     environmental stewardship.
                                    [ssquf] Marine Species Awareness
                                     Training. All bridge watch
                                     personnel, Commanding Officers,
                                     Executive Officers, maritime patrol
                                     aircraft aircrews, anti-submarine
                                     warfare and mine warfare rotary-
                                     wing aircrews, Lookouts, and
                                     equivalent civilian personnel must
                                     successfully complete the Marine
                                     Species Awareness Training prior to
                                     standing watch or serving as a
                                     Lookout. The Marine Species
                                     Awareness Training provides
                                     information on sighting cues,
                                     visual observation tools and
                                     techniques, and sighting
                                     notification procedures. Navy
                                     biologists developed Marine Species
                                     Awareness Training to improve the
                                     effectiveness of visual
                                     observations for biological
                                     resources, focusing on marine
                                     mammals and sea turtles, and
                                     including floating vegetation,
                                     jellyfish aggregations, and flocks
                                     of seabirds.
                                    [ssquf] U.S. Navy Protective
                                     Measures Assessment Protocol. This
                                     module provides the necessary
                                     instruction for accessing
                                     mitigation requirements during the
                                     event planning phase using the
                                     Protective Measures Assessment
                                     Protocol software tool.
                                    [ssquf] U.S. Navy Sonar Positional
                                     Reporting System and Marine Mammal
                                     Incident Reporting. This module
                                     provides instruction on the
                                     procedures and activity reporting
                                     requirements for the Sonar
                                     Positional Reporting System and
                                     marine mammal incident reporting.
Active Sonar.................  Depending on sonar source:
                                   1,000 yd (914.4 m) power
                                   down, 500 yd (457.2 m) power down,
                                   and 200 yd (182.9 m) shut down.
                                200 yd (182.9 m) shut down.
Air Guns.....................   150 yd (137.2 m).
Pile Driving.................   100 yd (91.4 m).
Weapons Firing Noise.........   30 degrees on either side of the
                                firing line out to 70 yd (64 m).
Explosive Sonobuoys..........   600 yd (548.6 m).
Explosive Torpedoes..........   2,100 yd (1,920.2 m).
Explosive Medium-Caliber and    1,000 yd (914.4 m; large-caliber
 Large-Caliber Projectiles.     projectiles).
                                600 yd (548.6 m; medium-caliber
                                projectiles during surface-to-surface
                                activities).
                                200 yd (182.9 m; medium-caliber
                                projectiles during air-to-surface
                                activities).
Explosive Missiles and          2,000 yd (1,828.8 m; 21-500 lb.
 Rockets.                       net explosive weight).
                                900 yd (823 m; 0.6-20 lb. net
                                explosive weight).
Explosive Bombs..............   2,500 yd (2,286 m).
Sinking Exercises............   2.5 nmi (4.6 km).
Explosive Mine Countermeasure   2,100 yd (1,929.2 m; 6-650 lb
 and Neutralization             net explosive weight).
 Activities.                    600 yd (548.6 m; 0.1-5 lb net
                                explosive weight).
Explosive Mine Neutralization   1,000 yd (914.4 m; 21-60 lb net
 Activities Involving Navy      explosive weight for positive control
 Divers.                        charges and charges using time-delay
                                fuses).
                                500 yd (457.2 m; 0.1-20 lb net
                                explosive weight for positive control
                                charges).
Underwater Demolition           700 yd (640.1 m).
 Multiple Charge--Mat Weave
 and Obstacle Loading.
Maritime Security Operations--  200 yd (182.9 m).
 Anti-Swimmer Grenades.
Vessel Movement..............   The mitigation must not be
                                applied if: (1) The vessel's safety is
                                threatened, (2) the vessel is restricted
                                in its ability to maneuver (e.g., during
                                launching and recovery of aircraft or
                                landing craft, during towing activities,
                                when mooring), (3) the vessel is
                                operated autonomously, or (4) when
                                impractical based on mission
                                requirements (e.g., during Amphibious
                                Assault--Battalion Landing exercises).
                                Number of Lookouts and
                                Observation Platform:
                                  [cir] Lookout must be on the vessel
                                   that is underway.\1\
                                Mitigation Requirements:
                                  [cir] Mitigation zones:--500 yd (457.2
                                   m) around whales.--200 yd (182.9 m)
                                   around other marine mammals (except
                                   bow-riding dolphins and pinnipeds
                                   hauled out on man-made navigational
                                   structures, port structures, and
                                   vessels).
                                  [cir] When a vessel is underway, Navy
                                   personnel must observe the mitigation
                                   zone for marine mammals; if marine
                                   mammals are observed, Navy personnel
                                   must maneuver (which may include
                                   reducing speed as the mission or
                                   circumstances allow) to maintain
                                   distance.
                                Additional requirements:
                                  [cir] If a marine mammal vessel strike
                                   occurs, Navy personnel must follow
                                   the established incident reporting
                                   procedures. Navy personnel must also
                                   send alerts to Navy vessels of
                                   increased risk of strike following
                                   any reported Navy vessel strike in
                                   the HSTT Study Area.

[[Page 4987]]

 
                                  [cir] Navy personnel must issue real-
                                   time notifications to Navy vessels of
                                   large whale aggregations (four or
                                   more whales) within 1 nmi (1.9 km) of
                                   a Navy vessel in the area between 32-
                                   33 degrees North and 117.2-119.5
                                   degrees West. These notifications
                                   would be issued to Navy vessels
                                   within this boundary only.
Towed In-Water Devices.......   250 yd (228.6 m; marine
                                mammals).
Small-, Medium-, and Large-     200 yd (182.9 m).
 Caliber Non-Explosive
 Practice Munitions.
Non-Explosive Missiles and      900 yd (823 m).
 Rockets.
Non-Explosive Bombs and Mine    1,000 yd (914.4 m).
 Shapes.
------------------------------------------------------------------------
Note: lb: pounds; nmi: nautical miles; yd: yards; m: meters.
\1\ Underway vessels will maintain at least one Lookout. For ship
  classes required to maintain more than one Lookout, the specific
  requirement is subject to change over time in accordance with Navy
  navigation instruction (e.g., the Surface Ship NAVDORM). Navy
  personnel will notify NMFS as soon as practicable should its Lookout
  policies change, including in the NAVDORM.


         Table 9--Summary of Mitigation Areas for Marine Mammals
------------------------------------------------------------------------
                 Summary of mitigation area requirements
-------------------------------------------------------------------------
Hawaii Island Mitigation Area (year-round)
     Navy personnel must not conduct more than 300 hours of MF1
     surface ship hull-mounted mid-frequency active sonar or 20 hours of
     MF4 dipping sonar, or use explosives that could potentially result
     in takes of marine mammals during training and testing.\1\
4-Islands Region Mitigation Area (November 15-April 15 for active sonar;
 year-round for explosives)
     Navy personnel must not use MF1 surface ship hull-mounted
     mid-frequency active sonar or explosives that could potentially
     result in takes of marine mammals during training and testing.\1\
Humpback Whale Special Reporting Areas (December 15-April 15)
     Navy personnel must report the total hours of surface ship
     hull-mounted mid-frequency active sonar used in the special
     reporting areas in its annual training and testing activity reports
     submitted to NMFS.
San Diego Arc, San Nicolas Island, and Santa Monica/Long Beach
 Mitigation Areas (June 1-October 31)
     Navy personnel must not conduct more than a total of 200
     hours of MF1 surface ship hull-mounted mid-frequency active sonar
     in the combined areas, excluding normal maintenance and systems
     checks, during training and testing.\1\
     Within the San Diego Arc Mitigation Area, Navy personnel
     must not use explosives that could potentially result in the take
     of marine mammals during large-caliber gunnery, torpedo, bombing,
     and missile (including 2.75'' rockets) activities during training
     and testing.\1\
     Within the San Nicolas Island Mitigation Area, Navy
     personnel must not use explosives that could potentially result in
     the take of marine mammals during mine warfare, large-caliber
     gunnery, torpedo, bombing, and missile (including 2.75'' rockets)
     activities during training.\1\
     Within the Santa Monica/Long Beach Mitigation Area, Navy
     personnel must not use explosives that could potentially result in
     the take of marine mammals during mine warfare, large-caliber
     gunnery, torpedo, bombing, and missile (including 2.75'' rockets)
     activities during training and testing.\1\
Santa Barbara Island Mitigation Area (year-round)
     Navy personnel must not use MF1 surface ship hull-mounted
     mid-frequency active sonar during training and testing, or
     explosives that could potentially result in the take of marine
     mammals during medium-caliber or large-caliber gunnery, torpedo,
     bombing, and missile (including 2.75'' rockets) activities during
     training.\1\
Awareness Notification Message Areas (seasonal according to species)
     Navy personnel must issue spring awareness notification
     messages to alert ships and aircraft to the possible presence of
     large whales during a period based on predicted oceanographic
     conditions for a given year. The message must emphasize to
     personnel on vessels that when a marine mammal is spotted, this may
     be an indicator that additional marine mammals are present and
     nearby, and increased vigilance and awareness of Navy personnel is
     warranted. Navy personnel must also issue awareness notification
     messages to alert ships and aircraft to the possible presence of
     gray whales (November-March) and fin whales (November-May).
------------------------------------------------------------------------
\1\ If Naval units need to conduct more than the specified amount of
  training or testing, they will obtain permission from the appropriate
  designated Command authority prior to commencement of the activity.
  The Navy will provide NMFS with advance notification and include the
  information in its annual activity reports submitted to NMFS.

Mitigation Conclusions

    NMFS has carefully evaluated the Navy's mitigation measures from 
the 2020 rule--many of which were developed with NMFS' input during the 
previous phases of Navy training and testing authorizations and none of 
which have changed since our evaluation during the 2018 HSTT 
rulemaking, with the exception of the changes described herein--and 
considered a broad range of other measures (i.e., the measures 
considered but eliminated in the 2018 HSTT FEIS/OEIS, which reflect 
many of the comments that have arisen via NMFS or public input in past 
years) in the context of ensuring that NMFS prescribes the means of 
effecting the least practicable adverse impact on the affected marine 
mammal species and stocks and their habitat. Our evaluation of 
potential measures included consideration of the following factors in 
relation to one another: the manner in which, and the degree to which, 
the successful implementation of the mitigation measures is expected to 
reduce the likelihood and/or magnitude of adverse impacts to marine 
mammal species and stocks and their habitat; the proven or likely 
efficacy of the measures; and the practicability of the measures for 
applicant implementation, including consideration of personnel safety, 
practicality of implementation, and impact on the effectiveness of the 
military readiness activity. After considering all new information, 
including consideration of new information regarding vessel strike, 
NMFS is requiring two additional mitigation measures and revision of 
two existing mitigation measures as described above.
    Based on our evaluation of the Navy's current mitigation measures 
(which are being implemented under the 2020 HSTT regulations), as well 
as modified and new measures described above, NMFS has determined that 
the mitigation measures are appropriate means of effecting the least 
practicable adverse impact on marine mammal species or stocks and their 
habitat, paying particular attention to rookeries, mating grounds, and 
areas of similar significance, and considering specifically personnel 
safety, practicality of implementation, and impact on the effectiveness 
of the military readiness activity. Additionally, as described in more 
detail below, the 2020 HSTT final rule includes an adaptive management 
provision, which NMFS has included in this final rule, which ensures 
that mitigation is regularly assessed and

[[Page 4988]]

provides a mechanism to improve the mitigation, based on the factors 
above, through modification as appropriate.

Monitoring

    Section 101(a)(5)(A) of the MMPA states that in order to authorize 
incidental take for an activity, NMFS must set forth requirements 
pertaining to the monitoring and reporting of such taking. The MMPA 
implementing regulations at 50 CFR 216.104(a)(13) indicate that 
requests for incidental take authorizations must include the suggested 
means of accomplishing the necessary monitoring and reporting that will 
result in increased knowledge of the species and of the level of taking 
or impacts on populations of marine mammals that are expected to be 
present.
    In its 2022 application, the Navy proposed no changes to the 
monitoring described in the 2018 HSTT final rule and 2020 HSTT final 
rule. They would continue implementation of the robust Integrated 
Comprehensive Monitoring Program and Strategic Planning Process 
described in the 2018 HSTT final rule. The Navy's monitoring strategy, 
currently required by the 2018 HSTT regulations, is well-designed to 
work across Navy ranges to help better understand the impacts of the 
Navy's activities on marine mammals and their habitat by focusing on 
learning more about marine mammal occurrence in different areas and 
exposure to Navy stressors, marine mammal responses to different sound 
sources, and the consequences of those exposures and responses on 
marine mammal populations. Similarly, these modified regulations would 
include identical adaptive management provisions and reporting 
requirements as the 2018 HSTT regulations. There is no new information 
that would indicate that the monitoring measures put in place under the 
2018 HSTT final rule would not remain applicable and appropriate for 
the 7-year period of this rule. See the Monitoring section of the 2018 
HSTT final rule for more details on the monitoring program that would 
be required under this rule. In addition, please see the 2019 Navy 
application, which references chapter 13 of the 2017 Navy application 
for full details on the monitoring and reporting proposed by the Navy.
    Within the SOCAL portion of HSTT, the Navy has been primarily 
focused on beaked whale monitoring since 2018 through two separate 
ongoing projects that are expected to continue until 2025. These 
projects use passive acoustic devices, visual surveys, satellite 
tagging, genetic analysis, photoID, and response to anthropogenic 
sounds to refine population status of beaked whales in SOCAL. There is 
also one concurrent project with fin whales using visual surveys, 
satellite tagging, and photoID to gather additional data on fin whale 
populations in Southern California. Finally, the Navy continues to fund 
marine mammal sighting data collected during California Cooperative 
Oceanic Fisheries Investigations (CALCOFI) https://calcofi.org/. These 
data are collected on a much more frequent basis than NMFS' West Coast 
visual survey which typically occur once every 5 years in the summer. 
CALCOFI surveys occur quarterly every year to include winter and spring 
seasons NMFS does not survey. Sufficient marine mammal sightings have 
been accumulated since the Navy started funding in 2004 for the data to 
be incorporated into ongoing NMFS spatial habitat models, including new 
models for select species. The Navy also annually funds continued NMFS 
spatial habitat model improvements as new data and techniques become 
available. These models benefit the Navy and other Federal partners 
such as the Bureau of Ocean Energy Management and NMFS, for use in 
future regional marine mammal density derivation. For additional 
information, please see the Navy's Marine Species Monitoring program 
website, https://www.navymarinespeciesmonitoring.us/regions/pacific/current-projects/.

Adaptive Management

    The 2020 HSTT regulations governing the take of marine mammals 
incidental to Navy training and testing activities in the HSTT Study 
Area contain an adaptive management component. Our understanding of the 
effects of Navy training and testing activities (e.g., acoustic and 
explosive stressors) on marine mammals continues to evolve, which makes 
the inclusion of an adaptive management component both valuable and 
necessary within the context of 7-year regulations. The 2022 Navy 
application proposed no changes to the adaptive management component 
included in the 2020 HSTT final rule.
    The reporting requirements associated with this rule are designed 
to provide NMFS with monitoring data from the previous year to allow 
NMFS to consider whether any changes to existing mitigation and 
monitoring requirements are appropriate. The use of adaptive management 
allows NMFS to consider new information from different sources to 
determine (with input from the Navy regarding practicability) on an 
annual or biennial basis if mitigation or monitoring measures should be 
modified (including additions or deletions). Mitigation measures could 
be modified if new data suggests that such modifications would have a 
reasonable likelihood of more effectively accomplishing the goals of 
the mitigation and monitoring and if the measures are practicable. If 
the modifications to the mitigation, monitoring, or reporting measures 
are substantial, NMFS will publish a notice of the planned LOA in the 
Federal Register and solicit public comment.
    The following are some of the possible sources of applicable data 
to be considered through the adaptive management process: (1) results 
from monitoring and exercises reports, as required by MMPA 
authorizations; (2) compiled results of Navy funded R&D studies; (3) 
results from specific stranding investigations; (4) results from 
general marine mammal and sound research; and (5) any information which 
reveals that marine mammals may have been taken in a manner, extent, or 
number not authorized by these regulations or subsequent LOAs. The 
results from monitoring reports and other studies may be viewed at 
https://www.navymarinespeciesmonitoring.us.

Reporting

    In order to issue incidental take authorization for an activity, 
section 101(a)(5)(A) of the MMPA states that NMFS must set forth 
requirements pertaining to the monitoring and reporting of such taking. 
Effective reporting is critical both to compliance as well as ensuring 
that the most value is obtained from the required monitoring. Reports 
from individual monitoring events, results of analyses, publications, 
and periodic progress reports for specific monitoring projects will be 
posted to the Navy's Marine Species Monitoring web portal: http://www.navymarinespeciesmonitoring.us. The 2019 Navy application and 2022 
Navy application proposed no changes to the reporting requirements, 
though as noted above, the Navy has since proposed to report changes to 
Lookout SOPs to NMFS. Except as discussed below, reporting requirements 
would remain identical to those described in the 2018 HSTT final rule 
and 2020 HSTT final rule, and there is no new information that would 
indicate that the reporting requirements put in place under the 2020 
HSTT final rule would not remain applicable and appropriate for the 
remaining duration of the 7-year period of this rule. See the Reporting 
section of the 2018 HSTT final rule for more details on the reporting 
that would be required under this rulemaking. In addition, the 2018 
HSTT proposed and final rules unintentionally failed to

[[Page 4989]]

include the requirement for the Navy to submit a final activity ``close 
out'' report at the end of the regulatory period. That oversight was 
corrected through the 2020 HSTT final rule. Please see the 2020 HSTT 
final rule for the detailed requirements for that report.
    In addition to the reporting requirements included in the 2020 HSTT 
final rule, in 2023, we proposed requiring the Navy to report changes 
in its Lookout policies to NMFS as soon as practicable after a change 
is made. This final rule requires the Navy to implement that reporting 
measure, as well as two new measures that were not included in the 2023 
HSTT proposed rule, described below.
    The Navy's annual HSTT Training Exercise Report and Testing 
Activity Report must include information that tracks the Navy's 
implementation of the new SOCAL large whale aggregation real-time 
reporting mitigation measure. The report must include the following 
information for each instance that an aggregation of large whales is 
reported: (1) the date, time and general location (e.g., approximately 
10-12 nmi (18.5 to 22.2 km) SE of San Clemente Island) of the whales 
when the aggregation was first sighted; (2) the total number of whales 
observed within 1 nmi (1.8 km) of a Navy vessel that make up the 
aggregation; and (3) the approximate distance (or distances if more 
than one group of whales is sighted) of the vessel from the whales in 
the aggregation when the whales were first sighted. To the extent 
practicable, this information should be provided in the Navy's 
unclassified version of these reports.
    The Navy's annual HSTT Training Exercise Report and Testing 
Activity Report must include a confirmation 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 U.S. Navy's 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, which formed the basis of the acoustic impacts 
effects analysis used to estimate take in this final rule. The purpose 
of this new reporting measure is for the Navy to confirm annually that 
the Navy has accounted for foreign military participation in its annual 
report, without requiring the Navy to quantitatively account for 
foreign military activity. The Navy informed NMFS that it would be 
difficult for the Navy to quantify foreign military activities as a 
subset of its total activities because the Navy does not track 
activities conducted by foreign vessels in this manner. Furthermore, 
the annual reported takes from Navy activities are calculated the same 
regardless of whether the activity was conducted by a foreign military 
or not.

Analysis and Negligible Impact Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). While this final rule consists of a modification of 
take by M/SI by vessel strike, NMFS considers the impacts of the entire 
specified activity and the total taking in the negligible impact 
determination. An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
taken through mortality, serious injury, and Level A or Level B 
harassment (as presented in tables 11 and 12 of the 2020 HSTT final 
rule), NMFS considers other factors, such as the likely nature of any 
responses (e.g., intensity, duration), the context of any responses 
(e.g., critical reproductive time or location, migration), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities (including foreign military activities) are 
incorporated into this analysis via their impacts on the environmental 
baseline (e.g., as reflected in the regulatory status of the species, 
population size and growth rate where known, other ongoing sources of 
human-caused mortality, ambient noise levels, and specific 
consideration of take by Level A harassment or M/SI previously 
authorized for other NMFS activities).
    In the Estimated Take of Marine Mammals sections of this final rule 
and the 2020 HSTT final rule (where the activities, species and stocks, 
potential effects, and mitigation measures (except as modified above) 
are the same as for this rulemaking), we identified the subset of 
potential effects that would be expected to rise to the level of takes 
both annually and over the 7-year period covered by this rulemaking and 
then identified the number of each of those mortality takes that we 
believe could occur or the maximum number of harassment takes that are 
reasonably expected to occur based on the methods described. The impact 
that any given take will have is dependent on many case-specific 
factors that need to be considered in the negligible impact analysis 
(e.g., the context of behavioral exposures such as duration or 
intensity of a disturbance, the health of impacted animals, the status 
of a species that incurs fitness-level impacts to individuals, etc.). 
For this final rule, we evaluated the likely impacts of the enumerated 
maximum number of harassment takes that were reasonably expected to 
occur and are authorized, in the context of the specific circumstances 
surrounding these predicted takes. We also assessed M/SI takes that 
could occur, as well as considering the traits and statuses of the 
affected species and stocks. Last, we collectively evaluated this 
information, as well as other more taxa-specific information and 
mitigation measure effectiveness, in group-specific assessments that 
support our negligible impact conclusions for each stock or species. 
Because all of the Navy's specified activities would occur within the 
ranges of the marine mammal stocks identified in the rule, all 
negligible impact analyses and determinations are at the stock level 
(i.e., additional species-level determinations are not needed).
    The Navy proposed no changes to the nature or level of the 
specified activities or the boundaries of the HSTT Study Area, and 
therefore, the training and testing activities (e.g., equipment and 
sources used, exercises conducted) are the same as those analyzed in 
the 2020 HSTT final rule. In addition, the mitigation, monitoring, and 
nearly all reporting measures are identical to those described and 
analyzed in the 2018 HSTT final rule with the exception of changes to 
mitigation measures and the additional reporting requirements described 
previously. There is no new information since the publication of the 
2020 HSTT final rule regarding the impacts of the specified activities 
on marine mammals, the status and distribution of any of the affected 
marine mammal species or stocks, or the effectiveness of the mitigation 
and monitoring measures that would change the content of our analyses, 
with the exception of that described below. First, naval vessel strikes 
have occurred in the HSTT and Atlantic Fleet Training and Testing 
(AFTT) Study Areas since

[[Page 4990]]

publication of the 2020 HSTT final rule (one fin or sei whale struck by 
the U.S. Navy in the HSTT Study Area (2023), two unidentified large 
whales struck by the U.S. Navy in the HSTT Study Area (2021), two fin 
whales struck by a foreign navy in the HSTT Study Area (2021), and one 
dolphin struck by the U.S. Navy in the AFTT Study Area (2021)). Second, 
for gray whales, we have considered the latest effects of the recently 
closed UME on the west coast of North America along with the effects of 
the Navy's activities in the negligible impact analysis. Third, a new 
study suggests that Lookout detection of marine mammals is less certain 
than previously assumed (Oedekoven and Thomas, 2022). Fourth, stock 
assessments have been updated for multiple stocks in the 2023 Pacific 
and Alaska SARs (Carretta et al. 2024; Young et al. 2024).
    As described above, since publication of the 2023 HSTT proposed 
rule, NMFS has updated our Technical Guidance (NMFS, 2024) containing 
updated acoustic criteria for auditory injury (89 FR 36762, October 24, 
2024). The Technical Guidance provides updated auditory injury 
thresholds, where appropriate, as well as revised weighting functions, 
in some cases. For impulsive sources, the Updated Technical Guidance's 
auditory injury thresholds generally remain identical or are higher 
compared to our 2018 Technical Guidance, meaning that received levels 
would need to be higher in order for marine mammals to be expected to 
incur auditory injury. The exceptions are for phocid pinnipeds (PW), 
where the cumulative SEL threshold, in the Updated Technical Guidance, 
is 2 dB lower and for otariid pinnipeds (OW) where the peak sound 
pressure level threshold is 2 dB lower and the cumulative SEL threshold 
is 18 dB lower. As for the Updated Technical Guidance's weighting 
functions, for MF cetaceans (now called HF cetaceans in the updated 
document) and HF cetaceans (now called VHF cetaceans in the updated 
document), the weighting functions reflect a higher susceptibility to 
auditory injury at frequencies below 10 kHz, as compared to the 2018 
Technical Guidance. Other minor changes/shifts to weighting functions 
(e.g., for LF cetaceans, PW pinnipeds, OW pinnipeds) were also 
included. This new information was not available in a timeframe in 
which NMFS could have incorporated it into the quantitative analysis 
supporting this final rulemaking; however, NMFS did consider the 
information qualitatively. While these changes in the auditory injury 
thresholds and weighting functions could result in minor increases in 
PTS exposure estimates for some species, given the conservative 
assumptions built into the take estimate methodology, they would not be 
expected to result in meaningful, if any, changes in take estimates and 
would not be expected to change any of the findings.

Harassment

    As described in the Estimated Take of Marine Mammals section, the 
annual number of takes authorized and reasonably expected to occur by 
Level A harassment and Level B harassment (based on the maximum number 
of activities per 12-month period) are identical to those presented in 
tables 41 and 42 in the Take Requests section of the 2018 HSTT final 
rule, with the exception of humpback whale, which are presented in 
tables 2 and 3 herein. As such, the negligible impact analyses and 
determinations of the effects of the estimated Level A harassment and 
Level B harassment takes on annual rates of recruitment or survival for 
each species and stock are nearly identical to and substantively 
unchanged from those presented in the 2020 HSTT final rule. The 
differences in the analysis is our removal of consideration of 
California Sea Lion UME and gray whale UME, which have been closed 
since publication of the 2020 HSTT final rule and 2023 HSTT proposed 
rule, respectively, and incorporation of the revised stock structure 
for humpback whales. This does not affect the results of the analyses 
or our determinations. For detailed discussion of the impacts that 
affected individuals may experience given the specific characteristics 
of the specified activities and required mitigation (e.g., from 
behavioral disruption, masking, and temporary or permanent threshold 
shift), along with the effects of the expected Level A harassment and 
Level B harassment take on reproduction and survival, see the 
applicable subsections in the Analysis and Negligible Impact 
Determination section of the 2018 HSTT final rule (83 FR 66977-67018; 
also incorporated by reference in the 2020 HSTT final rule).

Serious Injury or Mortality

    Based on the information and methods discussed in the Estimated 
Take of Marine Mammals section (which are identical to those used in 
the 2018 HSTT final rule for explosives and revised for vessel strike), 
NMFS is authorizing five mortalities of large whales due to vessel 
strike over the 7-year period of this rulemaking, two more strikes than 
what was authorized in the 2018 HSTT final rule and 2020 HSTT final 
rule. Across the 7-year duration of the rule, take of an annual average 
of 0.57 gray whales (Eastern North Pacific stock) and fin whales (CA/
OR/WA stock), an annual average of 0.29 humpback whales (Hawaii stock) 
and an annual average of 0.14 blue whales (Eastern North Pacific 
stock), sei whales (Eastern North Pacific stock) and humpback whales 
(Mainland Mexico-CA/OR/WA stock, Mexico DPS), as described in table 7 
(i.e., one, two, or four take(s) over 7 years divided by seven to get 
the annual number) could occur and are authorized.

                                                   Table 10--Summary Information Related to Mortalities Requested for Vessel Strike, 2018-2025
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                   Annual
                                                 authorized                                                                            Residual
                                        Stock      take by     Total     Fisheries  interactions    Annual rate of M/SI                PBR (PBR                              Recent UME (Y/N);
          Species (stock)             abundance    serious   annual M/  (Y/N); annual rate  of M/ from  vessel collision     PBR *       minus       Stock trend * \4\    number and year (since
                                      (Nbest) *   injury or   SI * \2\     SI  from fisheries                *                        annual  M/                                   2007)
                                                  mortality                  interactions *                                             SI) \3\
                                                     \1\
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale (CA/OR/WA stock).........      11,065        0.57     >=43.4  Y; >=0.41...............  Y, 43.................          80        36.6  [uarr]................  N
Gray whale (Eastern North Pacific        26,960        0.57        131  Y, 9.3..................  Y, 1.8................         801         670  \5\ [uarr]............  Y; 690; 2019
 stock).
Humpback whale (Mainland Mexico-CA/       3,477        0.14         22  Y; 11.4.................  \6\ Y, 10.15..........          65      \7\ 43  Unknown...............  N
 OR/WA stock, Mexico DPS).
Humpback whale (Hawaii stock)......      11,278        0.29      27.09  Y; 8.39.................  \8\ Y, 10.59..........         127       99.91  Unknown...............  Y; 52; 2015

[[Page 4991]]

 
Blue whale (Eastern North Pacific         1,898        0.14     >=18.6  Y; >=0.61...............  Y, 18.................         4.1       -14.5  Unknown...............  Y; 3, 2007
 Stock).
Sei whale (Eastern North Pacific            864        0.14        >=0  N; 0....................  Y, 0..................        1.25        1.25  Unknown...............  N
 Stock).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* Presented in the 2023 final SARs.
\1\ This column represents the annual take by serious injury or mortality (M/SI) by vessel collision and was calculated by the number of mortalities authorized divided by 7 years (the length
  of the rule and LOAs).
\2\ This column represents the total number of incidents of M/SI that could potentially accrue to the specified species or stock. This number comes from the SAR, but deducts the takes accrued
  from either Navy strikes or NMFS' Southwest Fisheries Science Center (SWFSC) takes in the SARs to ensure not double-counted against PBR. However, for these species, there were no takes from
  either other Navy activities or SWFSC in the SARs to deduct that would be considered double-counting.
\3\ This value represents the calculated PBR less the average annual estimate of ongoing anthropogenic mortalities (i.e., total annual human-caused M/SI, which is presented in the SARs).
\4\ See relevant SARs for more information regarding stock status and trends.
\5\ The Pacific 2023 SAR indicates that the stock trend is increasing. However, recent (2023-2024) surveys conducted by NMFS' Southwest Fisheries Science Center indicated that the estimated
  total abundance of gray whales during the 2023-2024 southbound migration was 19,260, though the authors note that this stock has historically shown a pattern of population growth and decline
  that has not impacted the population in the long term (Eguchi et al. 2024).
\6\ Vessel strike of the Mainland Mexico-CA/OR/WA stock was calculated by applying a prorated portion of humpback whale strikes modeled by Rockwood et al. (2017) to this stock.
\7\ For this stock, PBR is currently set at 43 for U.S. waters and 65 for the stock's entire range. As the HSTT Study Area extends beyond U.S. waters and activities have the potential to
  impact the entire stock, we present the analysis using the PBR for the stock's entire range.
\8\ Annual vessel strike for this stock reported in the 2023 final SAR was calculated by summing vessel strike data from Hawaii, Alaska, and Washington. All observed strikes in Hawaii were
  assigned to the Hawaii stock, and a portion of observed strikes in Alaska were assigned to the Hawaii stock. Vessel strike of the Hawaii stock in Washington waters was calculated by applying
  a prorated portion of humpback whale strikes modeled by Rockwood et al. (2017) to the Hawaii stock.

    The Navy also requested a small number of takes by M/SI from 
explosives in the 2017 Navy application. To calculate the annual 
average of mortalities for explosives in table 11, we used the same 
method as described for vessel strikes. The annual average is the total 
number of takes over 7 years divided by seven. Specifically, NMFS is 
authorizing the following M/SI takes from explosives: five California 
sea lions and eight short-beaked common dolphins over the 7-year period 
(therefore 0.71 mortalities annually for California sea lions and 1.14 
mortalities annually for short-beaked common dolphin), as described in 
table 11. As this annual number is the same as that analyzed and 
authorized in the 2020 HSTT final rule, and no other relevant 
information about the status, abundance, or effects of mortality on 
each species or stock has changed, the analysis of the effects of 
explosives is identical to that presented in the 2020 HSTT final rule.

                                     Table 11--Summary Information Related to Mortalities from Explosives, 2018-2025
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                               Annual
                                             authorized                   Fisheries                    SWFSC       Residual
                                    Stock      take by     Total    interactions  (Y/N);             authorized    PBR- PBR                 UME  (Y/N);
        Species (stock)           abundance    serious   annual  M/ annual rate  of M/SI    PBR *       take        minus     Stock trend    number and
                                  (nbest) *   injury or   SI * \2\     from  fisheries                (annual)    annual  M/     * \5\          year
                                              mortality                interactions *                   \3\         SI and
                                                 \1\                                                              SWFSC \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
California sea lion (U.S.           257,606        0.71      >=321  Y; >=197............    14,011            6       13,684      [uarr]   N
 stock).
Short-beaked common dolphin (CA/  1,056,308        1.14     >=30.5  Y; >=30.5...........     8,889          2.8      8,855.7     unknown   N
 OR/WA stock).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Presented in the 2023 SARs.
\1\ This column represents the annual take by serious injury or mortality (M/SI) during explosive detonations and was calculated by the number of
  mortalities planned for authorization divided by 7 years (the length of the rule and LOAs).
\2\ This column represents the total number of incidents of M/SI that could potentially accrue to the specified species or stock. This number comes from
  the SAR.
\3\ This column represents annual take authorized through NMFS' SWFSC rulemaking/LOAs (86 FR 3840, January 15, 2021).
\4\ This value represents the calculated PBR less the average annual estimate of ongoing anthropogenic mortalities (i.e., total annual human-caused M/SI
  column and the annual authorized take from the SWFSC column. In the case of California sea lion the M/SI column (321) and the annual authorized take
  from the SWFSC (6) were subtracted from the calculated PBR of 14,011. In the case of short-beaked common dolphin the M/SI column (30.5) and the annual
  authorized take from the SWFSC (2.8) were subtracted from the calculated PBR of 8,889.
\5\ See relevant SARs for more information regarding stock status and trends.

    See the Serious Injury or Mortality subsection in the Analysis and 
Negligible Impact Determination section of the 2018 HSTT final rule (83 
FR 66985-66993, December 27, 2018) for detailed discussions of the 
impacts of M/SI, including a description of how the agency uses the PBR 
metric and other factors to inform our analysis and an analysis of the 
impacts on each species and stock for which M/SI is authorized, 
including the relationship of potential mortality for each species to 
the insignificance threshold and residual PBR, except as updated below.
Stocks With M/SI Below the Insignificance Threshold
    As noted in the Serious Injury or Mortality subsection of the 
Analysis and Negligible Impact Determination section in the 2018 HSTT 
final rule and 2020 HSTT final rule, for a species or stock with 
incidental M/SI less than 10 percent of residual PBR, we consider M/SI 
from the specified activities to represent an insignificant incremental 
increase in ongoing anthropogenic M/SI that alone (i.e., in the absence 
of any other take and barring any other unusual circumstances) will 
clearly not adversely affect annual rates of recruitment and survival. 
In this case, as

[[Page 4992]]

shown in table 10 and table 11, the following species or stocks have 
potential or estimated M/SI from vessel strike and explosive takes, 
respectively, and authorized below their insignificance threshold: fin 
whale (CA/OR/WA stock), gray whale (Eastern North Pacific stock), 
humpback whale (Hawaii stock and Mainland Mexico-CA/OR/WA stock), 
California sea lion (U.S stock), and short-beaked common dolphin (CA/
OR/WA stock). While the authorized M/SI of gray whales (Eastern North 
Pacific stock) is below the insignificance threshold, because of the 
recent UME, we further address how the authorized M/SI and the UME 
inform the negligible impact determination immediately below. For the 
other five stocks with authorized M/SI below the insignificance 
threshold, there are no other known factors, information, or unusual 
circumstances that indicate anticipated M/SI below the insignificance 
threshold could have adverse effects on annual rates of recruitment or 
survival and they are not discussed further. For the remaining stocks 
with anticipated potential M/SI above the insignificance threshold, how 
that M/SI compares to residual PBR, as well as additional factors, as 
appropriate, are discussed below as well.

Gray Whales (Eastern North Pacific Stock)

    The estimated and authorized lethal take of gray whale (Eastern 
North Pacific stock) is well below the insignificance threshold (0.57 
as compared to a residual PBR of 670). Nonetheless, we consider here 
how the 2019-2023 West Coast Gray Whale UME informs our negligible 
impact determination. Strandings of eastern North Pacific gray whales 
occurred in the United States, Canada and Mexico along the west coast 
of North America. They occurred in wintering, migratory, and feeding 
areas. Stranding rates have returned back to normal and expected 
levels, and the prevalence of thin live or thin dead whales has also 
decreased. The Investigative Team concluded localized ecosystem 
changes, including both access to and quality of prey, in the northern 
Bering and Chukchi seas caused the UME. These changes contributed to 
the poor nutritional condition observed in live whales in the wintering 
areas of Mexico and dead stranded gray whales in all three countries. 
This malnutrition led to increased mortality during the whales' annual 
northward migration (from Mexico to Alaska) and decreased production of 
calves. This resulted in an overall decline in population abundance. 
Because of the abundance and residual PBR of this stock, as well as the 
fact that the UME is closed and increased mortality stopped in late 
2023 (with peak strandings ending in December 2020), this UME is not 
expected to have any impacts on individuals during the period of this 
final rule, nor is it thought to have had impacts on the population 
rate when it was occurring that would influence our evaluation of the 
effects of the mortality authorized on the stock.
Stocks with M/SI Above the Insignificance Threshold

Blue Whale (Eastern North Pacific Stock)

    For blue whales (Eastern North Pacific stock), PBR is currently set 
at 4.1 and the total annual M/SI is estimated at greater than or equal 
to 18.6, yielding a residual PBR of -14.5. This is slightly higher than 
the 2020 HSTT final rule (-16.7) and 2023 HSTT proposed rule (-15.4). 
NMFS authorizes one M/SI for the Navy over the 7-year duration of the 
rule (indicated as 0.14 annually for the purposes of comparing to PBR 
and evaluating overall effects on annual rates of recruitment and 
survival), which means that residual PBR is exceeded by 14.5. However, 
as described in the 2018 and 2020 rules, given that the negligible 
impact determination is based on the assessment of take of the activity 
being analyzed, when total annual mortality from human activities is 
higher, but the impacts from the specific activity being analyzed are 
very small, NMFS may still find the impact of the authorized take from 
a specified activity to be negligible even if total human-caused 
mortality exceeds PBR if the authorized mortality is less than 10 
percent of PBR and management measures are being taken to address 
serious injuries and mortalities from the other activities causing 
mortality (i.e., other than the specified activities covered by the 
incidental take authorization in consideration). When those 
considerations are applied here, the authorized lethal take (0.14 
annually) of blue whales from the Eastern North Pacific stock is less 
than 10 percent of PBR (which is 4.1), and there are management 
measures in place to address M/SI from activities other than those the 
Navy is conducting (as discussed below). Perhaps more importantly, the 
available data suggests that the current number of vessel strikes is 
not likely to have an adverse impact on the population, despite the 
fact that it exceeds PBR, with the Navy's minimal additional mortality 
of one whale in the 7 years not creating the likelihood of adverse 
impact. Immediately below, we explain the information that supports our 
finding that the Navy's authorized M/SI is not expected to result in 
more than a negligible impact on this stock. As described previously, 
NMFS must also ensure that impacts by the applicant on the species or 
stock from other types of take (i.e., harassment) do not combine with 
the impacts from mortality to adversely affect the species or stock via 
impacts on annual rates of recruitment or survival, which occurs 
further below in the stock-specific conclusion sections.
    As discussed in the 2018 HSTT final rule and the 2020 HSTT final 
rule, the 2018 draft SAR and the more recent SARs rely on a new method 
to estimate annual deaths by vessel strike utilizing an encounter 
theory model that combined species distribution models of whale 
density, vessel traffic characteristics, and whale movement patterns 
obtained from satellite-tagged animals in the region to estimate 
encounters that would result in mortality (Rockwood et al. 2017). The 
model predicts 18 annual mortalities of blue whales from vessel 
strikes, which, with the additional M/SI of 1.54 from fisheries 
interactions, results in the current estimate of residual PBR being -
15.4. Although NMFS' Permits and Conservation Division in the Office of 
Protected Resources has independently reviewed the vessel strike model 
and its results and agrees that it is appropriate for estimating blue 
whale mortality by vessel strike on the U.S. West Coast, for analytical 
purposes we also note that if the historical method were used to 
predict vessel strike (i.e., using observed mortality by vessel strike, 
or 0.6, instead of 18), then total human-caused mortality including the 
Navy's potential take would not exceed PBR. We further note that the 
authors (Rockwood et al. 2017) do not suggest that vessel strike 
suddenly increased to 18 recently. In fact, the model is not specific 
to a year, but rather offers a generalized prediction of vessel strike 
off the U.S. West Coast. Therefore, if the Rockwood et al. (2017) model 
is an accurate representation of vessel strike, then similar levels of 
vessel strike have been occurring in past years as well. Put another 
way, if the model is correct, for some number of years total-human-
caused mortality has been significantly underestimated and PBR has been 
similarly exceeded by a notable amount, and yet, the Eastern North 
Pacific stock of blue whales remains stable nevertheless.

[[Page 4993]]

    NMFS' 2023 SAR states that the current population trend is unknown, 
though there may be evidence of a population size increase since the 
1990s. The SAR further cites to Monnahan et al. (2015), which used a 
population dynamics model to estimate that the Eastern North Pacific 
blue whale population was at 97 percent of carrying capacity in 2013 
and to suggest that the observed lack of a population increase since 
the early 1990s was explained by density dependence, not impacts from 
vessel strike. This would mean that this stock of blue whales shows 
signs of stability and is not increasing in population size because the 
population size is at or nearing carrying capacity for its available 
habitat. In fact, we note that this population has maintained this 
status throughout the years that the Navy has consistently tested and 
trained at similar levels (with similar vessel traffic) in areas that 
overlap with blue whale occurrence, which would be another indicator of 
population stability.
    Monnahan et al. (2015) modeled vessel numbers, vessel strikes, and 
the population of the Eastern North Pacific blue whale population from 
1905 out to 2050 using a Bayesian framework to incorporate informative 
biological information and assign probability distributions to 
parameters and derived quantities of interest. The authors tested 
multiple scenarios with differing assumptions, incorporated 
uncertainty, and further tested the sensitivity of multiple variables. 
Their results indicated that there is no immediate threat (i.e., 
through 2050) to the population from any of the scenarios tested, which 
included models with 10 and 35 strike mortalities per year. Broadly, 
the authors concluded that, unlike other blue whale stocks, the Eastern 
North Pacific blue whales have recovered from 70 years of whaling and 
are in no immediate threat from vessel strikes. They further noted that 
their conclusion conflicts with the depleted and strategic designation 
under the MMPA as well as PBR specifically.
    As discussed, we also take into consideration management measures 
in place to address M/SI caused by other activities. The Channel 
Islands NMS staff coordinates, collects, and monitors whale sightings 
in and around the Vessel Speed Reduction (VSR) zones and the Channel 
Islands NMS region. Redfern et al. (2013) note that the most risky area 
for blue whales is the Santa Barbara Channel, where shipping lanes 
intersect with common feeding areas. The seasonally established 
Southern California VSR zone spans from Point Arguello to Dana Point, 
including the Traffic Separation Schemes in the Santa Barbara Channel 
and San Pedro Channel. Vessels transiting the area from May 1 through 
December 15, 2023 are recommended to exercise caution and voluntarily 
reduce speed to 10 kn (18.5 km per hour) or less for blue, humpback, 
and fin whales. (Note this is an expanded timeframe from the Whale 
Advisory Zone discussed in the 2020 HSTT final rule, which spanned June 
through November, though the effective period could change in future 
years.) Channel Island NMS observers collect information from aerial 
surveys conducted by NOAA, the U.S. Coast Guard, California Department 
of Fish and Game, and U.S. Navy chartered aircraft. Information on 
seasonal presence, movement, and general distribution patterns of large 
whales is shared with mariners, NMFS Office of Protected Resources, 
U.S. Coast Guard, California Department of Fish and Game, the Santa 
Barbara Museum of Natural History, the Marine Exchange of Southern 
California, and whale scientists. Real time and historical whale 
observation data collected from multiple sources can be viewed on the 
Point Blue Whale Database.
    In this case, 0.14 M/SI means one mortality in 1 of the 7 years and 
zero mortalities in 6 of those 7 years. Therefore, the Navy would not 
be contributing to the total human-caused mortality at all in 6 of the 
7, or 85.7 percent, of the years covered by this rulemaking. That means 
that even if a blue whale were to be struck, in 6 of the 7 years there 
could be no effect on annual rates of recruitment or survival from 
Navy-caused M/SI. Additionally, the loss of a male would have far less, 
if any, effect on population rates and absent any information 
suggesting that one sex is more likely to be struck than another, we 
can reasonably assume that there is a 50 percent chance that the single 
strike authorized by this rulemaking would be a male, thereby further 
decreasing the likelihood of impacts on the population rate. In 
situations like this where potential M/SI is fractional, consideration 
must be given to the lessened impacts anticipated due to the absence of 
M/SI in 6 of the 7 years and the fact that the single strike could be a 
male. Lastly, we reiterate that PBR is a conservative metric and also 
not sufficiently precise to serve as an absolute predictor of 
population effects upon which mortality caps would appropriately be 
based. This is especially important given the minor difference between 
zero and one across the 7-year period covered by this rulemaking, which 
is the smallest distinction possible when considering mortality. As 
noted above, Wade et al. (1998), authors of the paper from which the 
current PBR equation is derived, note that ``Estimating incidental 
mortality in 1 year to be greater than the PBR calculated from a single 
abundance survey does not prove the mortality will lead to depletion; 
it identifies a population worthy of careful future monitoring and 
possibly indicates that mortality-mitigation efforts should be 
initiated.'' The information included here indicates that the current 
population trend of this blue whale stock is unknown but likely 
approaching carrying capacity and has leveled off because of density-
dependence, not human-caused mortality, in spite of what might be 
otherwise indicated from the calculated PBR. Further, potential (and 
authorized) M/SI is below 10 percent of PBR and management actions are 
in place to minimize vessel strike from other vessel activity in one of 
the highest-risk areas for strikes. Based on the presence of the 
factors described above, we do not expect lethal take from Navy 
activities, alone, to adversely affect Eastern North Pacific blue 
whales through effects on annual rates of recruitment or survival. 
Nonetheless, the fact that total human-caused mortality exceeds PBR 
necessitates close attention to the remainder of the impacts (i.e., 
harassment) on the Eastern North Pacific stock of blue whales from the 
Navy's activities to ensure that the total authorized takes have a 
negligible impact on the species or stock. Therefore, this information 
will be considered in combination with our assessment of the impacts of 
authorized harassment takes in the Group and Species-Specific Analyses 
section that follows.

Sei Whale (Eastern North Pacific Stock)

    For sei whales (Eastern North Pacific stock), PBR is currently set 
at 1.25. The total annual M/SI is estimated at greater than or equal to 
0 in the 2023 SAR, yielding a residual PBR of 1.25. NMFS authorizes one 
M/SI for the Navy over the 7-year duration of the rule (indicated as 
0.14 annually for the purposes of comparing to PBR and evaluating 
overall effects on annual rates of recruitment and survival), which 
means that residual PBR is 1.11.
    We acknowledge that the 2023 vessel strike by the U.S. Navy could 
have been of a sei whale or a CA/OR/WA fin whale, and this strike is 
not quantitatively included in this PBR analysis (nor is it 
quantitatively included in the PBR analysis for CA/

[[Page 4994]]

OR/WA fin whale if both of the 2021 U.S. Navy strikes were fin whales) 
which relies on the 2023 SARs. However, consideration of the 2023 
strike would not change the total M/SI which NMFS compares to PBR, as 
the 2023 U.S. Navy strike occurred outside of the time period 
considered in the vessel strike analysis in the 2023 SAR. Therefore, 
while we acknowledge the 2023 U.S. Navy strike, in the quantitative 
analysis it is treated the same as other non-U.S. Navy strikes that 
occurred outside of the timeframe reflected in the total M/SI.
    Immediately below, we explain the information that supports our 
finding that the Navy's authorized M/SI is not expected to result in 
more than a negligible impact on this stock. As described previously, 
NMFS must also ensure that impacts by the applicant on the species or 
stock from other types of take (i.e., harassment) do not combine with 
the impacts from mortality to adversely affect the species or stock via 
impacts on annual rates of recruitment or survival, which occurs 
further below in the stock-specific conclusion sections.
    Of note, management measures are in place to address M/SI caused by 
other activities. The Channel Islands NMS staff coordinates, collects, 
and monitors whale sightings in and around the VSR zones and the 
Channel Islands NMS region. The seasonally established Southern 
California VSR zone spans from Point Arguello to Dana Point, including 
the Traffic Separation Schemes in the Santa Barbara Channel and San 
Pedro Channel. Vessels transiting the area from May 1 through December 
15, 2023 are recommended to exercise caution and voluntarily reduce 
speed to 10 kn (18.5 km per hour) or less. While the VSR zone is aimed 
at reducing risk of fatal vessel strike of blue, humpback, and fin 
whales, this measure is also anticipated to reduce risk to sei whales 
(note, this is an expanded timeframe from the Whale Advisory Zone 
discussed in the 2020 HSTT final rule, which spanned June through 
November, though the effective period could change in future years). 
Channel Island NMS observers collect information from aerial surveys 
conducted by NOAA, the U.S. Coast Guard, California Department of Fish 
and Game, and U.S. Navy chartered aircraft. Information on seasonal 
presence, movement, and general distribution patterns of large whales 
is shared with mariners, NMFS Office of Protected Resources, U.S. Coast 
Guard, California Department of Fish and Game, the Santa Barbara Museum 
of Natural History, the Marine Exchange of Southern California, and 
whale scientists. Real time and historical whale observation data 
collected from multiple sources can be viewed on the Point Blue Whale 
Database.
    Further, as stated in the 2023 SAR, the California swordfish drift 
gillnet fishery is the most likely U.S. fishery to interact with 
Eastern North Pacific sei whales, though there are zero estimated 
annual takes from this fishery given no observed entanglements from 
1990-2021 across 9,246 observed fishing sets (Carretta et al. (2022)). 
NMFS established the Pacific Offshore Cetacean Take Reduction Team in 
1996 and prepared an associated Plan (PCTRP) to reduce the risk of M/SI 
via fisheries interactions. In 1997, NMFS published final regulations 
formalizing the requirements of the PCTRP, including the use of pingers 
following several specific provisions and the employment of Skipper 
education workshops.
    In this case, 0.14 M/SI means one authorized mortality in 1 of the 
7 years and zero authorized mortalities in 6 of those 7 years. 
Therefore, the Navy's authorized take would not be contributing to the 
total human-caused mortality at all in 6 of the 7, or 85.7 percent, of 
the years covered by this rulemaking. That means that even if a sei 
whale were to be struck, in 6 of the 7 years there could be no effect 
on annual rates of recruitment or survival from Navy-caused M/SI. 
Additionally, the loss of a male would have far less, if any, effect on 
population rates and absent any information suggesting that one sex is 
more likely to be struck than another, we can reasonably assume that 
there is a 50 percent chance that the single strike authorized by this 
rulemaking would be a male, thereby further decreasing the likelihood 
of impacts on the population rate. In situations like this where 
potential M/SI is fractional, consideration must be given to the 
lessened impacts anticipated due to the absence of M/SI in 6 of the 7 
years and the fact that the single strike could be a male.
    Lastly, we reiterate that PBR is a conservative metric and also not 
sufficiently precise to serve as an absolute predictor of population 
effects upon which mortality caps would appropriately be based. This is 
especially important given the minor difference between zero and one 
across the 7-year period covered by this rulemaking, which is the 
smallest distinction possible when considering mortality. As noted 
above, Wade et al. (1998), authors of the paper from which the current 
PBR equation is derived, note that ``Estimating incidental mortality in 
1 year to be greater than the PBR calculated from a single abundance 
survey does not prove the mortality will lead to depletion; it 
identifies a population worthy of careful future monitoring and 
possibly indicates that mortality-mitigation efforts should be 
initiated.'' Even after qualitatively considering the possibility that 
the whale struck by Navy in 2023 was a sei whale, and based on the 
presence of the factors described above, we do not expect one 
authorized lethal take from Navy activities, alone, to adversely affect 
Eastern North Pacific sei whales through effects on annual rates of 
recruitment or survival. This information will be considered in 
combination with our assessment of the impacts of authorized harassment 
takes in the Group and Species-Specific Analyses section that follows.

Group and Species-Specific Analyses

    In addition to broader analyses of the impacts of the Navy's 
activities on mysticetes, odontocetes, and pinnipeds, the 2018 HSTT 
final rule contained detailed analyses of the effects of the Navy's 
activities in the HSTT Study Area on each affected species and stock 
and was updated, as appropriate, in the 2020 HSTT final rule. All of 
that information and analyses remain applicable and valid for our 
analyses of the effects of the same Navy activities on the same species 
and stocks, with the exception of humpback whale, for which the stock 
structure has been revised, and NMFS has updated its analyses 
accordingly for this final rule. See the Group and Species-Specific 
Analyses subsection in the Analysis and Negligible Impact Determination 
section of the 2018 HSTT final rule (83 FR 66993-67018). In addition, 
apart from the additional authorized incidental take by vessel strike 
of two large whales, the resulting changes to the average annual 
mortality estimates discussed above, and the revised humpback whale 
stock structure, no new information has been received since the 
publication of the 2020 HSTT final rule that significantly changes the 
analyses of the effects of the Navy's activities on each species and 
stock presented in the 2020 HSTT final rule (new information regarding 
vessel strike, the potential impact of the gray whale UME (now closed), 
and the revised humpback whale stock structure were discussed earlier 
in the rule).
    In the discussions below, the estimated Level B harassment takes 
represent instances of take, not the number of individuals taken (the 
much lower and less frequent Level A harassment takes are far more 
likely to

[[Page 4995]]

be associated with separate individuals), and in many cases, some 
individuals are expected to be taken more than one time while in other 
cases, a portion of individuals will not be taken at all. Below, we 
compare the total take numbers (including PTS, TTS, and behavioral 
disturbance) for species or stocks to their associated abundance 
estimates to evaluate the magnitude of impacts across the species or 
stock and to individuals. Specifically, when an abundance percentage 
comparison is below 100, it means that percentage or less of the 
individuals in the stock will be affected (i.e., some individuals will 
not be taken at all), that the average for those taken is 1 day per 
year, and that we would not expect any individuals to be taken more 
than a few times in a year. When it is more than 100 percent, it means 
there will definitely be some number of repeated takes of individuals. 
For example, if the percentage is 300, the average would be each 
individual is taken on 3 days in a year if all were taken, but it is 
more likely that some number of individuals will be taken more than 
three times and some number of individuals fewer times or not at all. 
While it is not possible to know the maximum number of days across 
which individuals of a stock might be taken, in acknowledgement of the 
fact that it is more than the average, for the purposes of this 
analysis, we assume a number approaching twice the average. For 
example, if the percentage of take compared to the abundance is 800, we 
estimate that some individuals might be taken as many as 16 times. 
Those comparisons are included in the sections below. For some stocks, 
these numbers have been adjusted slightly (with these adjustments being 
in the single digits) so as to more consistently apply this approach, 
but these minor changes did not change the analysis or findings.
    To assist in understanding what this analysis means, we clarify a 
few issues related to estimated takes and the analysis here. An 
individual that incurs a PTS or TTS take may sometimes, for example, 
also be subject to behavioral disturbance at the same time. As 
described in the Harassment subsection of the Analysis and Negligible 
Impact Determination section of the 2018 HSTT final rule, the degree of 
PTS, and the degree and duration of TTS, expected to be incurred from 
the Navy's activities are not expected to impact marine mammals such 
that their reproduction or survival could be affected. Similarly, data 
do not suggest that a single instance in which an animal accrues PTS or 
TTS and is also subjected to behavioral disturbance would result in 
impacts to reproduction or survival. Alternately, we recognize that if 
an individual is subjected to behavioral disturbance repeatedly for a 
longer duration and on consecutive days, effects could accrue to the 
point that reproductive success is jeopardized (as discussed below in 
the stock-specific summaries). Accordingly, in analyzing the number of 
takes and the likelihood of repeated and sequential takes (which could 
result in reproductive impacts), we consider the total takes, not just 
the Level B harassment takes by behavioral disturbance, so that 
individuals potentially exposed to both threshold shift and behavioral 
disturbance are appropriately considered. We note that the same 
reasoning applies with the potential addition of behavioral disturbance 
to tissue damage from explosives, the difference being that we do 
already consider the likelihood of reproductive impacts whenever tissue 
damage occurs. Further, the number of Level A harassment takes by 
either PTS or tissue damage are so low compared to abundance numbers 
that it is considered highly unlikely that any individual would be 
taken at those levels more than once.
    Having considered all of the information and analyses previously 
presented in the 2018 HSTT final rule, including the Group and Species-
Specific Analyses discussions organized by the different groups and 
species, below we present tables showing instances of total take as a 
percentage of stock abundance for each group, updated with the new 
vessel strike calculations and humpback stock structure. We then 
summarize the information for each species or stock, considering the 
analysis from the 2018 HSTT final rule, 2020 HSTT final rule, and any 
new analysis. The analyses below in some cases address species 
collectively if they occupy the same functional hearing group (i.e., 
low, mid, and high-frequency cetaceans and pinnipeds in water), share 
similar life history strategies, and/or are known to behaviorally 
respond similarly to acoustic stressors. Because some of these groups 
or species share characteristics that inform the impact analysis 
similarly, it would be duplicative to repeat the same analysis for each 
species or stock. In addition, animals belonging to each stock within a 
species typically have the same hearing capabilities and behaviorally 
respond in the same manner as animals in other stocks within the 
species.
Mysticetes
    In tables 12 and 13 below for mysticetes, we indicate the total 
annual mortality, Level A harassment, and Level B harassment, and a 
number indicating the instances of total take as a percentage of 
abundance. Tables 12 and 13 have been updated from tables 18 and 19 in 
the 2020 HSTT final rule, as appropriate, with the 2023 final SARs and 
updated information on mortality, as discussed above. For additional 
information and analysis supporting the negligible-impact analysis, see 
the Mysticetes discussion in the Group and Species-Specific Analyses 
section of the 2018 HSTT final rule, all of which remains applicable to 
this rule unless specifically noted.

 Table 12--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Mysticetes in the HRC Portion of the HSTT Study Area and Number Indicating the Instances of Total
                                                                             Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Instances of indicated types of incidental take (not all    Total takes \a\          Abundance        Instance of total take
                                                                      takes represent separate individuals, especially for   --------------------------------------------      as percent of
                                                                                          disturbance)                                                                           abundance
                                                                   ----------------------------------------------------------                                            -----------------------
                                                                        Level B harassment          Level A                     Total             Total Navy              Total take   EEZ take
                Species                            Stock           ---------------------------    harassment                    takes     Takes    abundance  Within EEZ      as          as
                                                                                              ------------------               (entire   (within  inside and     Navy     percentage  percentage
                                                                                   TTS (may                       Mortality     study     Navy    outside of   abundance   of total     of Navy
                                                                     Behavioral  also include           Tissue       \b\        area)     EEZ)     EEZ (HRC)     (HRC)       Navy         EEZ
                                                                    disturbance  disturbance)   PTS     damage                                                             abundance   abundance
                                                                                                                                                                             (HRC)       (HRC)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale.............................  Central North Pacific....           15            33      0          0            0        48        40          43          33         112         121

[[Page 4996]]

 
Bryde's whale..........................  Hawaii...................           40           106      0          0            0       146       123         108          89         135         138
Fin whale..............................  Hawaii...................           21            27      0          0            0        48        41          52          40          92         103
Humpback whale.........................  Hawaii...................        2,837         6,289      3          0         0.29     9,129     7,389       5,078       4,595         180         161
Minke whale............................  Hawaii...................        1,233         3,697      2          0            0     4,932     4,030       3,652       2,835         135         142
Sei whale..............................  Hawaii...................           46           121      0          0            0       167       135         138         107         121         126
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the Hawaii take estimates, we compare predicted takes to abundance estimates generated from the same underlying density estimates (as described in the Estimated Take of Marine
  Mammals section of the 2018 HSTT final rule), both in and outside of the U.S. EEZ. Because the portion of the Navy's study area inside the U.S. EEZ is generally concomitant with the area
  used to generate the abundance estimates in the SARs, and the abundance predicted by the same underlying density estimates is the preferred abundance to use, there is no need to separately
  compare the take to the SARs abundance estimate.
\a\ Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.
\b\ The annual mortality of 0.29 is the result of no more than two mortalities over the course of 7 years from vessel strikes as described above in the Estimated Take of Marine Mammals
  section.


   Table 13--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Mysticetes in the SOCAL Portion of the HSTT Study Area and Number Indicating the Instances of
                                                                          Total Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                 Instances of indicated types of incidental take (not     Total          Abundance        Instance of total take
                                                                                 all takes represent separate individuals, especially     takes  ------------------------      as percent of
                                                                                                   for disturbance)                        \a\                                   abundance
                                                                              -------------------------------------------------------------------                        -----------------------
                                                                                   Level B harassment         Level A                                                     Total take
                                                                              ---------------------------    harassment                              Navy                     as      Total take
                   Species                                 Stock                                         -----------------                Total    abundance   NMFS SARs  percentage      as
                                                                                                                            Mortality     takes    in action   abundance   of total   percentage
                                                                                Behavioral    TTS (may                         \b\       (entire     area                    Navy      of total
                                                                               disturbance  also include   PTS    Tissue                  study     (SOCAL)                abundance      SAR
                                                                                            disturbance)          damage                  area)                            in action   abundance
                                                                                                                                                                             area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale..................................  Eastern North Pacific..........          792         1,196      1         0         0.14     1,989         785       1,898         253         105
Bryde's whale...............................  Eastern Tropical Pacific.......           14            27      0         0            0        41         1.3     unknown       3,154     unknown
Fin whale...................................  CA/OR/WA.......................          835         1,390      1         0         0.57     2,227         363      11,065         613          20
Humpback whale..............................  Central America/Southern Mexico-         282           594      0         0            0       876      \c\ 74       1,496       1,184          59
                                               CA/OR/WA.
                                              Mainland Mexico- CA/OR/WA......          198           920      1         0         0.14     1,119     \c\ 173       3,477         647          32
Minke whale.................................  CA/OR/WA.......................          259           666      1         0            0       926         163         915         568         101
Sei whale...................................  Eastern North Pacific..........           27            52      0         0         0.14        79           3         864       2,633           9
Gray whale..................................  Eastern North Pacific..........        1,316         3,355      7         0         0.57     4,679         193      26,960       2,424          17
Gray whale..................................  Western North Pacific..........            2             4      0         0            0         6           0         290           0           2
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the SOCAL take estimates, because of the manner in which the Navy study area overlaps the ranges of many MMPA stocks (i.e., a stock may range far north to Washington state and beyond
  and abundance may only be predicted within the U.S. EEZ, while the Navy study area is limited to Southern California and northern Mexico, but extends beyond the U.S. EEZ), we compare
  predicted takes to both the abundance estimates for the study area, as well as the SARs (as described in the Estimated Take of Marine Mammals section of the 2018 HSTT final rule).
\a\ Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.
\b\ The annual mortality of 0.14 is the result of no more than one mortality over the course of 7 years from vessel strikes as described above in the Estimated Take of Marine Mammals section.
  The annual mortality of 0.57 is the result of no more than four mortalities over the course of 7 years from vessel strikes.
\c\ In the 2020 HSTT final rule, NMFS reported a Navy abundance in Action Area (SOCAL) of 247 CA/OR/WA humpback whales. As explained in more detail in the Authorized Take From Vessel Strikes
  and Explosives by Serious Injury or Mortality section, NMFS estimates that approximately 30 percent of the humpback whales off the coast of California may be from the Central America DPS
  with the remaining 70 percent are expected to be from the Mexico DPS. Therefore, of the estimated 247 humpback whales in SOCAL, NMFS anticipates that 74 would be of the Central America/
  Southern Mexico-CA/OR/WA stock (Central America DPS), and 173 would be of the Mainland Mexico-CA/OR/WA stock (Mexico DPS).


[[Page 4997]]

    Below we compile and summarize the information that supports our 
determination that the Navy's activities will not adversely affect any 
species or stocks through effects on annual rates of recruitment or 
survival for any of the affected mysticete species and stocks.

Blue Whale (Eastern North Pacific Stock)

    Blue whales are listed as endangered under the ESA, and the current 
population trend for the Eastern North Pacific stock is unknown. We 
further note that this stock was originally listed under the ESA as a 
result of the impacts from commercial whaling, which is no longer 
affecting the species. NMFS authorizes one mortality over the 7 years 
covered by this rulemaking or 0.14 mortality annually. With the 
addition of this 0.14 annual mortality, residual PBR is exceeded, 
resulting in the total human-caused mortality exceeding PBR by 14.5. 
However, as described in more detail in the Serious Injury or Mortality 
section above, when total human-caused mortality exceeds PBR, we 
consider whether the incremental addition of a small amount of 
authorized mortality from the specified activity may still result in a 
negligible impact, in part by identifying whether it is less than 10 
percent of PBR. In this case, the authorized mortality is well below 10 
percent of PBR, management measures are in place to reduce mortality 
from other sources, and the incremental addition of a single mortality 
over the course of the 7-year Navy rule is not expected to, alone, lead 
to adverse impacts on the stock through effects on annual rates of 
recruitment or survival.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is 253 and 105 percent, respectively 
(table 13). Given the range of blue whales, this information suggests 
that only some portion of individuals in the stock are likely impacted, 
but that there will likely be some repeat exposure (maybe 5 or 6 days 
within a year) of some subset of individuals that spend extended time 
within SOCAL. Regarding the severity of those individual Level B 
harassment takes by behavioral disturbance, the duration of any 
exposure is expected to be between minutes and hours (i.e., relatively 
short) and the received sound levels largely below 172 dB with a 
portion up to 178 dB (i.e., of a moderate or lower level, less likely 
to evoke a severe response). Additionally, the Navy implements time/
area mitigation in SOCAL in the majority of the BIAs identified by 
Calambokidis et al. (2015). These areas overlap a portion of the blue 
whale feeding BIAs (parent and child; see Harrison et al. 2023) 
identified in Calambokidis et al. (2024) and will reduce the severity 
of impacts to blue whales by reducing interference in feeding that 
could result in lost feeding opportunities or necessitate additional 
energy expenditure to find other good opportunities. Regarding the 
severity of TTS takes, we have explained in the 2018 HSTT final rule 
that they are expected to be low-level, of short duration, and mostly 
not in a frequency band that would be expected to interfere with blue 
whale communication or other important low-frequency cues--and that the 
associated lost opportunities and capabilities are not at a level that 
will impact reproduction or survival. For similar reasons (as described 
in the 2018 HSTT final rule) the single estimated Level A harassment 
take by PTS for this stock is unlikely to have any effect on the 
reproduction or survival of that one individual, even if it were to be 
experienced by an animal that also experiences one or more Level B 
harassment takes by behavioral disturbance.
    Altogether, only a small portion of the stock is anticipated to be 
impacted and any individual blue whale is likely to be disturbed at a 
low-moderate level, with likely many animals exposed only once or twice 
and a subset potentially disturbed across 5 or 6 days but minimized in 
BIAs. This low magnitude and severity of harassment effects is not 
expected to result in impacts on the reproduction or survival of any 
individuals and, therefore, when combined with the authorized mortality 
(which our earlier analysis indicated will not, alone, have more than a 
negligible impact on this stock of blue whales), the total take is not 
expected to adversely affect this stock through impacts on annual rates 
of recruitment or survival. For these reasons, we have determined, in 
consideration of all of the effects of the Navy's activities combined, 
that the authorized take will have a negligible impact on the Eastern 
North Pacific stock of blue whales.

Bryde's Whale (Eastern Tropical Pacific Stock)

    Little is known about this stock or its status, and it is not 
listed under the ESA. No mortality or Level A harassment is anticipated 
or authorized. Regarding the magnitude of Level B harassment takes (TTS 
and behavioral disturbance), the number of estimated total instances of 
take compared to the abundance is 3,154 percent; however, the abundance 
upon which this percentage is based (1.3 whales from the Navy estimate, 
which is extrapolated from density estimates based on very few 
sightings) is clearly erroneous and the SAR does not include an 
abundance estimate because all of the survey data is outdated (table 
13). However, the abundance in the early 1980s was estimated as 22,000 
to 24,000, a portion of the stock was estimated at 13,000 in 1993, and 
the minimum number in the Gulf of California was estimated at 160 in 
1990. Given this information and the fact that 41 total takes of 
Bryde's whales were estimated, this information suggests that only a 
small portion of the individuals in the stock are likely impacted, and 
few, if any, are likely taken over more than 1 day. Regarding the 
severity of those individual Level B harassment takes by behavioral 
disturbance, the duration of any exposure is expected to be between 
minutes and hours (i.e., relatively short) and the received sound 
levels largely below 172 dB with a portion up to 178 dB (i.e., of a 
moderate or lower level, less likely to evoke a severe response). 
Regarding the severity of TTS takes, they are expected to be low-level, 
of short duration, and mostly not in a frequency band that would be 
expected to interfere with Bryde's whale communication or other 
important low-frequency cues. Any associated lost opportunities and 
capabilities are not at a level that will impact reproduction or 
survival.
    Altogether, only a small portion of the stock is anticipated to be 
impacted and any individual Bryde's whale is likely to be disturbed at 
a low-moderate level, with few, if any, individuals exposed over more 
than 1 day in the year. This low magnitude and severity of harassment 
effects is not expected to result in impacts on individual reproduction 
or survival, much less annual rates of recruitment or survival. For 
these reasons, we have determined, in consideration of all of the 
effects of the Navy's activities combined, that the authorized take 
will have a negligible impact on the Eastern Tropical Pacific stock of 
Bryde's whales.

Fin Whale (CA/OR/WA Stock)

    The SAR identifies this stock as ``increasing,'' even though the 
larger species is listed as endangered under the ESA. NMFS authorizes 
four mortalities over the 7 years covered by this rulemaking, or 0.57 
mortality annually. The addition of this 0.57 annual mortality still 
leaves the total human-caused mortality well under residual PBR.

[[Page 4998]]

    We acknowledge the 2021 vessel strike of two fin whales by the 
Royal Australian Navy, and that the 2021 and 2023 vessel strikes by the 
U.S. Navy could have been CA/OR/WA fin whales. While the Royal 
Australian Navy strikes are not quantitatively included in the 
estimated take by vessel strike, even if they were, and if we presumed 
that the 2021 and 2023 U.S. Navy strikes were all fin whales, M/SI of 
this stock would still fall well below PBR (80).
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is 613 and 20 percent, respectively 
(table 13). This information suggests that only some portion (less than 
25 percent) of individuals in the stock are likely impacted but that 
there is likely some repeat exposure (perhaps up to 12 days within a 
year) of some subset of individuals that spend extended time within the 
SOCAL complex. Some of these takes could occur on a few sequential days 
for some small number of individuals, for example, if they resulted 
from a multi-day exercise on a range while individuals were in the area 
for multiple days feeding. Regarding the severity of those individual 
Level B harassment takes by behavioral disturbance, the duration of any 
exposure is expected to be between minutes and hours (i.e., relatively 
short) and the received sound levels largely below 172 dB with a 
portion up to 178 dB (i.e., of a moderate or lower level, less likely 
to evoke a severe response). Additionally, Calambokidis et al. (2024) 
identifies feeding BIAs for fin whales in SOCAL. The Navy implements 
time/area mitigation in SOCAL in blue whale BIAs identified by 
Calambokidis et al. (2015), and fin whales are known to sometimes feed 
in some of the same areas. Additionally, these mitigation areas 
designed for blue whales overlap a portion of the fin whale feeding 
BIAs (parent and child; see Harrison et al. 2023) identified by 
Calambokidis et al. (2024) which means fin whales could potentially 
accrue some benefits from the mitigation. Regarding the severity of TTS 
takes, they are expected to be low-level, of short duration, and mostly 
not in a frequency band that would be expected to interfere with fin 
whale communication or other important low-frequency cues--and that the 
associated lost opportunities and capabilities are not at a level that 
will impact reproduction or survival. For similar reasons (as described 
in the 2018 HSTT final rule) the single estimated Level A harassment 
take by PTS for this stock is unlikely to have any effects on the 
reproduction or survival of that one individual.
    Altogether, this population is increasing, only a small portion of 
the stock is anticipated to be impacted, and any individual fin whale 
is likely to be disturbed at a low-moderate level, with the taken 
individuals likely exposed between 1 and 12 days, with a few 
individuals potentially taken on a few sequential days. This low 
magnitude and severity of harassment effects is not expected to result 
in impacts on individual reproduction or survival, and therefore, when 
combined with the authorized mortality (which our earlier analysis 
indicated will not, alone, have more than a negligible impact on this 
stock of fin whales), the total take is not expected to adversely 
affect this stock through impacts on annual rates of recruitment or 
survival. For these reasons, we have determined, in consideration of 
all of the effects of the Navy's activities combined, that the 
authorized take will have a negligible impact on the CA/OR/WA stock of 
fin whales.

Humpback Whale (Central America/Southern Mexico-CA/OR/WA Stock)

    The SAR identifies this stock as increasing, though the growth rate 
is uncertain. Animals in this stock are of the Central America DPS 
which is designated as endangered under the ESA.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is 1,184 and 59 percent, respectively 
(table 13). Given the range of humpback whales, this information 
suggests that only some portion of individuals in the stock are likely 
impacted but that there is likely some repeat exposure (perhaps up to 
23 days within a year) of some subset of individuals that spend 
extended time within the SOCAL complex. Regarding the severity of those 
individual Level B harassment takes by behavioral disturbance, the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB with a portion up to 178 dB (i.e., of a moderate or lower level, 
less likely to evoke a severe response). Some of these takes could 
occur on several sequential days for some small number of individuals, 
for example, if they resulted from a multi-day exercise on a range 
while individuals were in the area for multiple days feeding. However, 
these amounts are still not expected to adversely impact reproduction 
or survival of any individuals.
    Regarding the severity of TTS takes, they are expected to be low-
level, of short duration, and mostly not in a frequency band that would 
be expected to interfere with humpback whale communication or other 
important low-frequency cues--and that the associated lost 
opportunities and capabilities are not at a level that will impact 
reproduction or survival. Altogether, only a small portion of the stock 
is anticipated to be impacted and any individual humpback whale is 
likely to be disturbed at a low-moderate level, with likely many 
animals exposed only once or twice and a subset potentially disturbed 
up to 23 days, but with no reason to think that more than a few of 
those days would be sequential. This low magnitude and severity of 
harassment effects is not expected to result in impacts on the 
reproduction or survival of any individuals and, therefore, the total 
take is not expected to adversely affect this stock through impacts on 
annual rates of recruitment or survival. For these reasons, we have 
determined, in consideration of all of the effects of the Navy's 
activities combined, that the authorized take will have a negligible 
impact on the Central America/Southern Mexico-CA/OR/WA stock of 
humpback whales.

Humpback Whale (Mainland Mexico-CA/OR/WA Stock)

    The status of this stock is unknown. Animals in this stock are of 
the Mexico DPS which is designated as threatened under the ESA. NMFS 
authorizes one mortality over the 7 years covered by this rulemaking, 
or 0.14 mortality annually. The addition of this 0.14 annual mortality 
still leaves the total human-caused mortality well under residual PBR.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is 647 and 32 percent, respectively 
(table 13). Given the range of humpback whales, this information 
suggests that only some portion of individuals in the stock are likely 
impacted but that there is likely some repeat exposure (perhaps up to 
13 days within a year) of some subset of individuals that spend 
extended time within the SOCAL complex. Regarding the severity of those 
individual Level B harassment takes by behavioral disturbance, the 
duration of any exposure is expected to be between

[[Page 4999]]

minutes and hours (i.e., relatively short) and the received sound 
levels largely below 172 dB with a portion up to 178 dB (i.e., of a 
moderate or lower level, less likely to evoke a severe response). Some 
of these takes could occur on several sequential days for some small 
number of individuals, for example, if they resulted from a multi-day 
exercise on a range while individuals were in the area for multiple 
days feeding. However, these amounts are still not expected to 
adversely impact reproduction or survival of any individuals.
    Regarding the severity of TTS takes, they are expected to be low-
level, of short duration, and mostly not in a frequency band that would 
be expected to interfere with humpback whale communication or other 
important low-frequency cues--and that the associated lost 
opportunities and capabilities are not at a level that will impact 
reproduction or survival. For similar reasons (as described in the 2018 
HSTT final rule) the single estimated Level A harassment take by PTS 
for this stock is unlikely to have any effects on the reproduction or 
survival of that one individual.
    Altogether, only a small portion of the stock is anticipated to be 
impacted and any individual humpback whale is likely to be disturbed at 
a low-moderate level, with likely many animals exposed only once or 
twice and a subset potentially disturbed up to 13 days, but with no 
reason to think that more than a few of those days would be sequential. 
This low magnitude and severity of harassment effects is not expected 
to result in impacts on the reproduction or survival of any individuals 
and, therefore, when combined with the authorized mortality (which our 
earlier analysis indicated will not, alone, have more than a negligible 
impact on this stock of humpback whales), the total take is not 
expected to adversely affect this stock through impacts on annual rates 
of recruitment or survival. For these reasons, we have determined, in 
consideration of all of the effects of the Navy's activities combined, 
that the authorized take will have a negligible impact on the CA/OR/WA 
stock of humpback whales.

Minke Whale (CA/OR/WA Stock)

    The status of this stock is unknown and it is not listed under the 
ESA. No mortality from vessel strike or tissue damage from explosive 
exposure is anticipated or authorized for this species. Regarding the 
magnitude of Level B harassment takes (TTS and behavioral disturbance), 
the number of estimated total instances of take compared to the 
abundance (measured against both the Navy-estimated abundance and the 
SAR) is 568 and 101 percent, respectively (table 13). Based on the 
behaviors of minke whales, which often occur along continental shelves 
and sometimes establish home ranges along the West Coast, this 
information suggests that only a portion of individuals in the stock 
are likely impacted but that there is likely some repeat exposure 
(perhaps up to 11 days within a year) of some subset of individuals 
that spend extended time within the SOCAL complex. Some of these takes 
could occur on a few sequential days for some small number of 
individuals, for example, if they resulted from a multi-day exercise on 
a range while individuals were in the area for multiple days feeding. 
Regarding the severity of those individual Level B harassment takes by 
behavioral disturbance, the duration of any exposure is expected to be 
between minutes and hours (i.e., relatively short) and the received 
sound levels largely below 172 dB with a portion up to 178 dB (i.e., of 
a moderate or lower level, less likely to evoke a severe response). 
Regarding the severity of TTS takes, they are expected to be low-level, 
of short duration, and mostly not in a frequency band that would be 
expected to interfere with minke whale communication or other important 
low-frequency cues--and that the associated lost opportunities and 
capabilities are not at a level that will impact reproduction or 
survival. For similar reasons (as described in the 2018 HSTT final 
rule) the single estimated Level A harassment take by PTS for this 
stock is unlikely to have any effects on the reproduction or survival 
of that individual.
    Altogether, only a portion of the stock is anticipated to be 
impacted and any individual minke whale is likely to be disturbed at a 
low-moderate level, with the taken individuals likely exposed between 1 
and 11 days, with a few individuals potentially taken on a few 
sequential days. This low magnitude and severity of harassment effects 
is not expected to result in impacts on individual reproduction or 
survival, much less annual rates of recruitment or survival. For these 
reasons, we have determined, in consideration of all of the effects of 
the Navy's activities combined, that the authorized take will have a 
negligible impact on the CA/OR/WA stock of minke whales.

Sei Whale (Eastern North Pacific Stock)

    The status of this stock is unknown, and sei whales are listed 
under the ESA. NMFS authorizes one mortality over the 7 years covered 
by this rulemaking or 0.14 mortality annually. The addition of this 
0.14 annual mortality still leaves the total human-caused mortality 
under residual PBR. After additionally considering several qualitative 
factors described above, including that the 2023 strike could have been 
a sei whale (or fin whale), we do not expect one authorized lethal take 
from Navy activities, alone, to adversely affect Eastern North Pacific 
sei whales through effects on annual rates of recruitment or survival. 
No Level A harassment is anticipated or authorized.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is 2,633 and 9 percent, respectively 
(table 13), however, the abundance upon which the Navy percentage is 
based (3 from the Navy estimate, which is extrapolated from density 
estimates based on very few sightings) is likely an underestimate of 
the number of individuals in the HSTT study Area, resulting in an 
overestimated percentage. Given this information and the large range of 
sei whales, and the fact that only 79 total Level B harassment takes of 
sei whales were estimated, it is likely that some very small number of 
sei whales would be taken repeatedly, potentially up to 15 days in a 
year (typically 2,633 percent would lead to the estimate of 52 days/
year, however, given that there are only 79 sei whale total takes, we 
used the conservative assumption that five individuals might be taken 
up to 15 times, with the few remaining takes distributed among other 
individuals). Regarding the severity of those individual Level B 
harassment takes by behavioral disturbance, the duration of any 
exposure is expected to be between minutes and hours (i.e., relatively 
short) and the received sound levels largely below 172 dB with a 
portion up to 178 dB (i.e., of a moderate or lower level, less likely 
to evoke a severe response). Some of these takes could occur on a few 
sequential days for some small number of individuals, for example, if 
they resulted from a multi-day exercise on a range while individuals 
were in the area for multiple days feeding, however, these amounts are 
still not expected to adversely impact reproduction or survival of any 
individuals. Regarding the severity of TTS takes, they are expected to 
be low-level, of short duration, and mostly not in a frequency band 
that would be expected to interfere with sei whale communication or 
other important low-frequency cues--and that

[[Page 5000]]

the associated lost opportunities and capabilities are not at a level 
that will impact reproduction or survival.
    Altogether, only a small portion of the stock is anticipated to be 
impacted and any individual sei whale is likely to be disturbed at a 
low-moderate level, with only a few individuals exposed over one to 15 
days in a year, with no more than a few sequential days. This low 
magnitude and severity of harassment effects is not expected to result 
in impacts on individual reproduction or survival, and therefore, when 
combined with the authorized mortality (which our earlier analysis 
indicated will not, alone, have more than a negligible impact on this 
stock of sei whales), the total take is not expected to adversely 
affect this stock through impacts on annual rates of recruitment or 
survival. For these reasons, we have determined, in consideration of 
all of the effects of the Navy's activities combined, that the 
authorized take will have a negligible impact on the Eastern North 
Pacific stock of sei whales.

Gray Whale (Eastern North Pacific Stock)

    The Eastern North Pacific stock of gray whale is not ESA-listed and 
the SAR indicates that the stock is increasing. However, recent (2021-
2022) surveys conducted by NMFS' Southwest Fisheries Science Center 
estimated that the population has declined to 16,650 whales, though the 
authors note that this stock has historically shown a pattern of 
population growth and decline that has not impacted the population in 
the long term (Eguchi et al. 2022). NMFS is authorizing four 
mortalities over the 7 years covered by this rulemaking, or 0.57 
mortality annually. The addition of this 0.57 annual mortality still 
leaves the total human-caused mortality well under the insignificance 
threshold of residual PBR (670). We acknowledge that the 2021 vessel 
strikes by the U.S. Navy could have been Eastern North Pacific gray 
whales. If we presumed that the 2021 U.S. Navy strikes were both gray 
whales, M/SI of this stock would still fall well below PBR (801).
    We also consider here how the 2019-2023 West Coast Gray Whale UME 
informs our negligible impact determination. Because of the abundance 
and residual PBR of this stock, as well as the fact that the UME is 
closed and increased mortality stopped in late 2023 (with peak 
strandings ending in December 2020), this UME is not expected to have 
any impacts on individuals during the period of this final rule, nor is 
it thought to have had impacts on the population rate when it was 
occurring that would influence our evaluation of the effects of the 
mortality authorized on the stock.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is 2,424 and 17 percent, respectively 
(table 13). (Note that in comparison to the recent Eguchi et al. 2024 
abundance estimate, the number of estimated total instances of take 
compared to the abundance would be 24 percent.) This information 
suggests that only some small portion of individuals in the stock are 
likely impacted (less than 17 percent) but that there is likely some 
level of repeat exposure of some subset of individuals that spend 
extended time within the SOCAL complex. Typically 2,424 percent would 
lead to the estimate of 48 days/year, however, given that a large 
number of gray whales are known to migrate through the SOCAL complex 
and the fact that there are 4,679 total takes, we believe that it is 
more likely that a larger number of individuals will be taken one to a 
few times, while a small number staying in an area to feed for several 
days may be taken on 5-10 days. Regarding the severity of those 
individual Level B harassment takes by behavioral disturbance, the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB with a portion up to 178 dB (i.e., of a moderate or lower level, 
less likely to evoke a severe response). Some of these takes could 
occur on a couple of sequential days for some small number of 
individuals; however, these amounts are still not expected to adversely 
impact reproduction or survival of any individuals.
    Regarding the severity of TTS takes, they are expected to be low-
level, of short duration, and mostly not in a frequency band that would 
be expected to interfere with gray whale communication or other 
important low-frequency cues and that the associated lost opportunities 
and capabilities are not at a level that will impact reproduction or 
survival. For these same reasons (low level and frequency band), while 
a small permanent loss of hearing sensitivity may include some degree 
of energetic costs for compensating or may mean some small loss of 
opportunities or detection capabilities, at the expected scale the 
seven estimated Level A harassment takes by PTS for gray whales are 
unlikely to impact behaviors, opportunities, or detection capabilities 
to a degree that would interfere with reproductive success or survival 
of any individuals.
    Altogether, we have considered the impacts of the recent (now 
closed) gray whale UME, the Eastern North Pacific stock of gray whales 
is not endangered or threatened under the ESA. The SAR indicates that 
the stock is increasing. However, recent (2023-2024) surveys conducted 
by NMFS' Southwest Fisheries Science Center estimated that the 
population has declined since the most recent Eastern North Pacific 
gray whale SAR was published (Eguchi et al. 2024). Only a small portion 
of the stock is anticipated to be impacted and any individual gray 
whale is likely to be disturbed at a low-moderate level, with likely 
many animals exposed only once or twice and a subset potentially 
disturbed across 5 to 10 days. This low magnitude and severity of 
harassment effects is not expected to result in impacts to reproduction 
or survival for any individuals and, therefore, when combined with the 
authorized mortality of four whales over the 7 year period (which our 
earlier analysis indicated will not, alone, have more than a negligible 
impact on this stock of gray whales), the total take is not expected to 
adversely affect this stock through impacts on annual rates of 
recruitment or survival. For these reasons, we have determined, in 
consideration of all of the effects of the Navy's activities combined, 
that the authorized take will have a negligible impact on the Eastern 
North Pacific stock of gray whales.

Gray Whale (Western North Pacific Stock)

    The Western North Pacific stock of gray whales is reported as 
increasing in the 2023 final SAR but is listed as endangered under the 
ESA. No mortality or Level A harassment is anticipated or authorized. 
This stock is expected to incur the very small number of 6 Level B 
harassment takes (2 behavioral disruption and 4 TTS) to a stock with a 
SAR-estimated abundance of 290 (table 13). These takes will likely 
accrue to different individuals, the behavioral disturbances will be of 
a low-moderate level, and the TTS instances will be at a low level and 
short duration. This low magnitude and severity of harassment effects 
is not expected to result in impacts on individual reproduction or 
survival, much less to adversely affect this stock through impacts on 
annual rates of recruitment or survival. For these reasons, we have 
determined, in consideration of all of the effects of the Navy's 
activities combined, that the authorized take will have a negligible 
impact on the Western North Pacific stock of gray whales.

[[Page 5001]]

Humpback Whale (Hawaii Stock)

    The status of this stock is unknown. Animals in this stock are of 
the Hawaii DPS which is not listed under the ESA. No Level A harassment 
by tissue damage is authorized. NMFS authorizes two mortalities over 
the 7 years covered by this rulemaking, or 0.29 mortalities annually. 
The addition of this 0.29 annual mortality still leaves the total 
human-caused mortality well under the insignificance threshold for 
residual PBR.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated instances of take 
compared to the abundance, both throughout the HSTT Study Area and 
within the U.S. EEZ, respectively, is 180 and 161 percent (table 12). 
This information and the complicated far-ranging nature of the stock 
structure suggests that some portion of the stock (but not all) are 
likely impacted, over 1 to several days per year, with little 
likelihood of take across sequential days. Regarding the severity of 
those individual Level B harassment takes by behavioral disturbance, 
the duration of any exposure is expected to be between minutes and 
hours (i.e., relatively short) and the received sound levels largely 
below 172 dB with a portion up to 178 dB (i.e., of a moderate or lower 
level, less likely to evoke a severe response). Additionally, as noted 
above, there are two mitigation areas implemented by the Navy that span 
a large area of the important humpback reproductive areas (BIA, parent 
and child; see Harrison et al. 2023) identified in Kratofil et al. 
(2023) and minimize impacts by limiting the use of MF1 active sonar and 
explosives, thereby reducing both the number and severity of takes of 
humpback whales. Regarding the severity of TTS takes, they are expected 
to be low-level, of short duration, and mostly not in a frequency band 
that would be expected to interfere with humpback whale communication 
or other important low-frequency cues, and that the associated lost 
opportunities and capabilities are not at a level that will impact 
reproduction or survival. For these same reasons (low level and 
frequency band), while a small permanent loss of hearing sensitivity 
may include some degree of energetic costs for compensating or may mean 
some small loss of opportunities or detection capabilities, at the 
expected scale the 3 estimated Level A harassment takes by PTS for 
humpback whales are unlikely to impact behaviors, opportunities, or 
detection capabilities to a degree that would interfere with 
reproductive success or survival of any individuals.
    Altogether, this stock's status is unknown and the DPS is not 
listed as endangered or threatened under the ESA. Only a small portion 
of the stock is anticipated to be impacted and any individual humpback 
whale is likely to be disturbed at a low-moderate level, with the taken 
individuals likely exposed between 1 to several days per year, with 
little likelihood of take across sequential days. This low magnitude 
and severity of harassment effects is not expected to result in impacts 
on individual reproduction or survival, and therefore, when combined 
with the authorized mortality (which our earlier analysis indicated 
will not, alone, have more than a negligible impact on this stock of 
humpback whales), the total take is not expected to adversely affect 
this stock through effects on annual rates of recruitment or survival. 
For these reasons, we have determined, in consideration of all of the 
effects of the Navy's activities combined, that the authorized take 
will have a negligible impact on the Hawaii stock of humpback whales.

Blue Whale (Central North Pacific Stock) and the Hawaii Stocks of 
Bryde's Whale, Fin Whale, Minke Whale, and Sei Whale

    The status of these stocks are not identified in the SARs. Blue 
whale (Central North Pacific stock) and the Hawaii stocks of fin whale 
and sei whale are listed as endangered under the ESA; the Hawaii stocks 
of minke whales and Bryde's whales are not listed under the ESA. No 
mortality or Level A harassment by tissue damage is anticipated or 
authorized for any of these stocks.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated instances of take 
compared to the abundance, both throughout the HSTT Study Area and 
within the U.S. EEZ, respectively, is 92-135 and 103-142 percent (table 
12). This information suggests that some portion of the stocks (but not 
all) are likely impacted, over 1 to several days per year, with little 
likelihood of take across sequential days. Regarding the severity of 
those individual Level B harassment takes by behavioral disturbance, 
the duration of any exposure is expected to be between minutes and 
hours (i.e., relatively short) and the received sound levels largely 
below 172 dB with a portion up to 178 dB (i.e., of a moderate or lower 
level, less likely to evoke a severe response). Regarding the severity 
of TTS takes, they are expected to be low-level, of short duration, and 
mostly not in a frequency band that would be expected to interfere with 
mysticete communication or other important low-frequency cues--and that 
the associated lost opportunities and capabilities are not at a level 
that will impact reproduction or survival. For similar reasons (as 
described in the 2018 HSTT final rule) the two estimated Level A 
harassment takes by PTS for the Hawaii stock of minke whales are 
unlikely to have any effects on the reproduction or survival of any 
individuals.
    Altogether, only a portion of these stocks are anticipated to be 
impacted and any individuals of these stocks are likely to be disturbed 
at a low-moderate level, with the taken individuals likely exposed 
between 1 and several days, with little chance that any are taken 
across sequential days. This low magnitude and severity of harassment 
effects is not expected to result in impacts on individual reproduction 
or survival, much less have impacts on annual rates of recruitment or 
survival. For these reasons, we have determined, in consideration of 
all of the effects of the Navy's activities combined, that the 
authorized take will have a negligible impact on these stocks.
Odontocetes

Sperm Whale, Dwarf Sperm Whale, and Pygmy Sperm Whale

    In table 14 and table 15 below for sperm whale, dwarf sperm whale, 
and pygmy sperm whale, we indicate the total annual mortality (0 for 
all stocks; the 2020 HSTT final rule included 0.14 annual takes by 
mortality of the Hawaii stock of sperm whale), Level A and Level B 
harassment, and a number indicating the instances of total take as a 
percentage of abundance. Table 14 and table 15 are unchanged from 
tables 20 and 21 in the 2020 HSTT final rule, except for updated 
information on mortality for the Hawaii stock of sperm whales, as 
discussed above. For additional information and analysis supporting the 
negligible-impact analysis, see the Odontocetes discussion as well as 
the Sperm Whales, Dwarf Sperm Whales, and Pygmy Sperm Whales discussion 
in the Group and Species-Specific Analyses section of the 2018 HSTT 
final rule, all of which remains applicable to this rule unless 
specifically noted.

[[Page 5002]]



Table 14--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Sperm Whales, Dwarf Sperm Whales, and Pygmy Sperm Whales in the HRC Portion of the HSTT Study Area
                                                      and Number Indicating the Instances of Total Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Instances of indicated types of incidental take (not all      Total takes            Abundance          Instances of total
                                                                      takes represent separate individuals, especially for   --------------------------------------------   take as percent of
                                                                                          disturbance)                                                                           abundance
                                                                  -----------------------------------------------------------                                            -----------------------
                                                                       Level B harassment          Level A                      Total             Total Navy              Total take
                Species                           Stock           ---------------------------     harassment                    takes     Takes    abundance  Within EEZ      as       EEZ take
                                                                                             -------------------               (entire   (within  inside and     Navy     percentage      as
                                                                                  TTS (may                        Mortality     study     NAVY      outside    abundance   of total   percentage
                                                                    Behavioral  also include           Tissue                   area)     EEZ)     EEZ (HRC)     (HRC)       Navy       of EEZ
                                                                   disturbance  disturbance)   PTS     damage                                                              abundance   abundance
                                                                                                                                                                             (HRC)       (HRC)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Dwarf sperm whale.....................  Hawaii...................        5,870        14,550     64           0            0    20,484    15,310       8,218       6,379         249         240
Pygmy sperm whale.....................  Hawaii...................        2,329         5,822     29           0            0     8,180     6,098       3,349       2,600         244         235
Sperm whale...........................  Hawaii...................        2,466            30      0           0            0     2,496     1,317       1,656       1,317         151         147
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the Hawaii take estimates, we compare predicted takes to abundance estimates generated from the same underlying density estimates (as described in the Estimated Take of Marine
  Mammals section of the 2018 HSTT final rule), both in and outside of the U.S. EEZ. Because the portion of the Navy's study area inside the U.S. EEZ is generally concomitant with the area
  used to generate the abundance estimates in the SARs, and the abundance predicted by the same underlying density estimates is the preferred abundance to use, there is no need to separately
  compare the take to the SARs abundance estimate.
Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.


  Table 15--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Sperm Whales, Dwarf Sperm Whales, and Pygmy Sperm Whales in the SOCAL Portion of the HSTT Study
                                                    Area and Number Indicating the Instances of Total Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Instances of indicated types of incidental take (not all    Total          Abundance          Instances of total
                                                                                takes represent separate individuals, especially for      takes  ------------------------   take as percent  of
                                                                                                    disturbance)                       ----------                                abundance
                                                                            -----------------------------------------------------------                                  -----------------------
                                                                                 Level B harassment          Level A                                                      Total take
                                                                            ---------------------------     harassment                    Total      Navy                     as      Total take
                  Species                                 Stock                                        -------------------                takes    abundance   NMFS SARS  percentage      as
                                                                                                                                         (entire   in action   abundance   of total   percentage
                                                                              Behavioral    TTS (may                        Mortality     study      area                    Navy      of total
                                                                             disturbance  also include   PTS     Tissue                   area)                            abundance      SAR
                                                                                          disturbance)           damage                                                    in action   abundance
                                                                                                                                                                             area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Kogia whales...............................  CA/OR/WA......................        2,779         6,353     38           0            0     9,170         757       4,111       1,211         223
Sperm whale................................  CA/OR/WA......................        2,437            56      0           0            0     2,493         273       2,606         913          96
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the SOCAL take estimates, because of the manner in which the Navy study area overlaps the ranges of many MMPA stocks (i.e., a stock may range far north to Washington state and beyond
  and abundance may only be predicted within the U.S. EEZ, while the Navy study area is limited to Southern California and northern Mexico, but extends beyond the U.S. EEZ), we compare
  predicted takes to both the abundance estimates for the study area, as well as the SARs (as described in the Estimated Take of Marine Mammals section of the 2018 HSTT final rule).
Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.

    Below we compile and summarize the information that supports our 
determination that the Navy's activities will not adversely affect any 
species or stocks through effects on annual rates of recruitment or 
survival for any of the affected species and stocks addressed in this 
section. Sperm Whale, Dwarf Sperm Whale, and Pygmy Sperm Whale (CA/OR/
WA Stocks)
    The SAR identifies the CA/OR/WA stock of sperm whales as 
``stable'', and the species is listed as endangered under the ESA. The 
status of the CA/OR/WA stocks of pygmy and dwarf sperm whales is 
unknown and neither are listed under the ESA. Neither mortality nor 
Level A harassment by tissue damage from exposure to explosives is 
expected or authorized for any of these three stocks.
    Due to their pelagic distribution, small size, and cryptic 
behavior, pygmy sperm whales and dwarf sperm whales are rarely sighted 
during at-sea surveys and are difficult to distinguish between when 
visually observed in the field. Many of the relatively few observations 
of Kogia spp. off the U.S. West Coast were not identified to species. 
All at-sea sightings of Kogia spp. have been identified as pygmy sperm 
whales or Kogia spp. Stranded dwarf sperm and pygmy sperm whales have 
been found on the U.S. West Coast, however dwarf sperm whale strandings 
are rare. NMFS SARs suggest that the majority of Kogia sighted off the 
U.S. West Coast were likely pygmy sperm whales. As such, the stock 
estimate in the NMFS SAR for pygmy sperm whales is the estimate derived 
for all Kogia spp. in the region (Barlow, 2016), and no separate 
abundance estimate can be determined for dwarf sperm whales, though 
some low number likely reside in the U.S. EEZ. Due to the lack of 
abundance estimate, it is not possible to predict the take of dwarf 
sperm whales and take estimates are identified as Kogia spp. (including 
both pygmy and dwarf sperm whales). We assume only a small portion of 
those takes are likely to be dwarf sperm whales as the density and 
abundance in the U.S. EEZ is thought to be low.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is, respectively, 913 and 96 for sperm 
whales and 1,211 and 223 for Kogia spp., with a large proportion of 
these anticipated to be pygmy sperm whales due to the low abundance and 
density of dwarf sperm whales in the HSTT Study Area (table 15). Given 
the

[[Page 5003]]

range of these stocks (which extends the entire length of the West 
Coast, as well as beyond the U.S. EEZ boundary), this information 
suggests that some portion of the individuals in these stocks will not 
be impacted but that there is likely some repeat exposure (perhaps up 
to 24 days within a year for Kogia spp. and 18 days a year for sperm 
whales) of some small subset of individuals that spend extended time 
within the SOCAL Range. Additionally, while interrupted feeding bouts 
are a known response and concern for odontocetes, we also know that 
there are often viable alternative habitat options in the relative 
vicinity. Regarding the severity of those individual Level B harassment 
takes by behavioral disturbance, the duration of any exposure is 
expected to be between minutes and hours (i.e., relatively short) and 
the received sound levels largely below 172 dB (i.e., of a lower, to 
occasionally moderate, level and less likely to evoke a severe 
response). However, some of these takes could occur on a fair number of 
sequential days for some number of individuals.
    Regarding the severity of TTS takes, they are expected to be low-
level, of short duration, and mostly not in a frequency band that would 
be expected to interfere with sperm whale communication or other 
important low-frequency cues, and that the associated lost 
opportunities and capabilities are not at a level that will impact 
reproduction or survival. For these same reasons (low level and 
frequency band), while a small permanent loss of hearing sensitivity 
(PTS) may include some degree of energetic costs for compensating or 
may mean some small loss of opportunities or detection capabilities, at 
the expected scale the estimated Level A harassment takes by PTS for 
the dwarf and pygmy sperm whale stocks are unlikely to impact 
behaviors, opportunities, or detection capabilities to a degree that 
would interfere with reproductive success or survival of any 
individuals. Thus, the 38 total Level A harassment takes by PTS for 
these 2 stocks are unlikely to affect rates of recruitment and survival 
for the stocks.
    Altogether, most members of the stocks will likely be taken by 
Level B harassment (at a low to occasionally moderate level) over 
several days a year, and some smaller portion of the stocks are 
expected to be taken on a relatively moderate to high number of days 
(up to 18 or 24) across the year, some of which could be sequential 
days. Though the majority of impacts are expected to be of a lower to 
sometimes moderate severity, the larger number of takes for a subset of 
individuals makes it more likely that a small number of individuals 
could be interrupted during foraging in a manner and amount such that 
impacts to the energy budgets of females (from either losing feeding 
opportunities or expending considerable energy to find alternative 
feeding options) could cause them to forego reproduction for a year. 
Energetic impacts to males are generally meaningless to population 
rates unless they cause death, and it takes extreme energy deficits 
beyond what would ever be likely to result from these activities to 
cause the death of an adult marine mammal. As discussed in the 2020 
HSTT final rule, however, foregone reproduction (especially for 1 year, 
which is the maximum predicted because the small number anticipated in 
any 1 year makes the probability that any individual would be impacted 
in this way twice in 7 years very low) has far less of an impact on 
population rates than mortality, and a small number of instances of 
foregone reproduction are not expected to adversely affect these stocks 
through effects on annual rates of recruitment or survival. We also 
note that residual PBR is 19 for pygmy sperm whales and 3.5 for sperm 
whales. Both the abundance and PBR are unknown for dwarf sperm whales, 
however, we know that take of this stock is likely significantly lower 
in magnitude and severity (i.e., lower number of total takes and 
repeated takes any individual) than pygmy sperm whales. For these 
reasons, in consideration of all of the effects of the Navy's 
activities combined, we have determined that the authorized take will 
have a negligible impact on the CA/OR/WA stocks of sperm whales and 
pygmy and dwarf sperm whales.
Sperm Whale (Hawaii Stock)
    The SAR does not identify a trend for this stock and the species is 
listed as endangered under the ESA. No mortality or Level A harassment 
by PTS or tissue damage is expected or authorized.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated instances of take 
compared to the abundance, both throughout the HSTT Study Area and 
within the U.S. EEZ, respectively, is 151 and 147 percent (table 14). 
This information and the sperm whale stock range suggest that likely 
only a smaller portion of the stock will be impacted, over 1 to several 
days per year, with little likelihood of take across sequential days. 
Regarding the severity of those individual Level B harassment takes by 
behavioral disturbance, the duration of any exposure is expected to be 
between minutes and hours (i.e., relatively short) and the received 
sound levels largely below 172 dB (i.e., of a lower, to occasionally 
moderate, level and less likely to evoke a severe response). Regarding 
the severity of TTS takes, they are expected to be low-level, of short 
duration, and mostly not in a frequency band that would be expected to 
interfere with sperm whale communication or other important low-
frequency cues, and that the associated lost opportunities and 
capabilities are not at a level that will impact reproduction or 
survival.
    Altogether, a relatively small portion of this stock is anticipated 
to be impacted and any individuals are likely to be disturbed at a low-
moderate level, with the taken individuals likely exposed between 1 and 
several days, with little chance that any are taken across sequential 
days. This low magnitude and severity of harassment effects is not 
expected to result in impacts on individual reproduction or survival, 
much less annual rates of recruitment or survival. For these reasons, 
we have determined, in consideration of all of the effects of the 
Navy's activities combined, that the authorized take will have a 
negligible impact on the Hawaii stock of sperm whales.
Pygmy and Dwarf Sperm Whales (Hawaii Stocks)
    The SAR does not identify a trend for these stocks and the species 
are not listed under the ESA. No Level A harassment by tissue damage is 
anticipated or authorized. Regarding the magnitude of Level B 
harassment takes (TTS and behavioral disturbance), the number of 
estimated instances of take compared to the abundance, both throughout 
the HSTT Study Area and within the U.S. EEZ, respectively, is 244-249 
and 235-240 percent (table 14). This information and the pygmy and 
dwarf sperm whale stock ranges (at least throughout the U.S. EEZ around 
the entire Hawaiian Islands) suggest that likely a fair portion of each 
stock is not impacted, but that a subset of individuals may be taken 
over one to perhaps 5 days per year, with little likelihood of take 
across sequential days. Regarding the severity of those individual 
Level B harassment takes by behavioral disturbance, the duration of any 
exposure is expected to be between minutes and hours (i.e., relatively 
short) and the received sound levels largely below 172 dB (i.e., of a 
lower, to occasionally moderate, level and less likely to evoke a 
severe response). Additionally, as discussed earlier, within the Hawaii 
Island Mitigation

[[Page 5004]]

Area, explosives are not used and the use of MF1 and MF4 active sonar 
is limited, greatly reducing the severity of impacts within the small 
and resident population BIA for dwarf sperm whales (Kratofil et 
al.2023), which is entirely contained within this mitigation area.
    Regarding the severity of TTS takes, they are expected to be low-
level, of short duration, and mostly not in a frequency band that would 
be expected to interfere with sperm whale communication or other 
important low-frequency cues--and that the associated lost 
opportunities and capabilities are not at a level that will impact 
reproduction or survival. For these same reasons (low level and 
frequency band), while a small permanent loss of hearing sensitivity 
may include some degree of energetic costs for compensating or may mean 
some small loss of opportunities or detection capabilities, at the 
expected scale, estimated Level A harassment takes by PTS for dwarf and 
pygmy sperm whales are unlikely to impact behaviors, opportunities, or 
detection capabilities to a degree that would interfere with 
reproductive success or survival of any individuals, even if it were to 
be experienced by an animal that also experiences one or more instances 
of Level B harassment by behavioral disturbance. Thus the 29 and 64 
total Level A harassment takes by PTS for dwarf and pygmy sperm whales, 
respectively, are unlikely to affect rates of recruitment and survival 
for these stocks.
    Altogether, a portion of these stocks are likely to be impacted and 
any individuals are likely to be disturbed at a low-moderate level, 
with the taken individuals likely exposed between 1 and 5 days, with 
little chance that any are taken across sequential days. This low 
magnitude and severity of Level A and Level B harassment effects is not 
expected to result in impacts on individual reproduction or survival, 
much less impacts on annual rates of recruitment or survival. For these 
reasons, we have determined, in consideration of all of the effects of 
the Navy's activities combined, that the expected and authorized take 
will have a negligible impact on the Hawaii stocks of pygmy and dwarf 
sperm whales.

Beaked Whales

    In table 16 and table 17 below for beaked whales, we indicate the 
total annual mortality, Level A and Level B harassment, and a number 
indicating the instances of total take as a percentage of abundance. 
Table 16 and table 17 are unchanged from table 22 and table 23 in the 
2020 HSTT final rule, with the exception of a correction to a rounding 
error as noted. For additional information and analysis supporting the 
negligible-impact analysis, see the Odontocetes discussion as well as 
the Beaked Whales discussion in the Group and Species-Specific Analyses 
section of the 2018 HSTT final rule, all of which remains applicable to 
this rule unless specifically noted.

  Table 16--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Beaked Whales in the HRC Portion of the HSTT Study Area and Number Indicating the Instances of
                                                                          Total Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Instances of indicated types of incidental take (not all      Total takes            Abundance          Instances of total
                                                                      takes represent separate individuals, especially for   --------------------------------------------   take as percent of
                                                                                          disturbance)                                                                           abundance
                                                                  -----------------------------------------------------------                                            -----------------------
                                                                       Level B harassment      Level A harassment               Total             Total Navy              Total take
                Species                           Stock           ------------------------------------------------              takes     Takes    abundance  Within EEZ      as       EEZ take
                                                                                                                               (entire   (within  inside and     Navy     percentage      as
                                                                                  TTS (may                         Mortality    study     Navy      outside    abundance   of total   percentage
                                                                    Behavioral  also include     PTS      Tissue                area)     EEZ)     EEZ (HRC)     (HRC)       Navy       of EEZ
                                                                   disturbance  disturbance)              damage                                                           abundance   abundance
                                                                                                                                                                             (HRC)       (HRC)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Blainville's beaked whale.............  Hawaii...................        5,369            16          0         0          0     5,385     4,140         989         768     \a\ 544         539
Goose-beaked whale....................  Hawaii...................        1,792             4          0         0          0     1,796     1,377         345         268         521         514
Longman's beaked whale................  Hawaii...................       19,152            81          0         0          0    19,233    14,585       3,568       2,770         539         527
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the Hawaii take estimates, we compare predicted takes to abundance estimates generated from the same underlying density estimates (as described in the Estimated Take of Marine
  Mammals section of the 2018 HSTT final rule), both in and outside of the U.S. EEZ. Because the portion of the Navy's study area inside the U.S. EEZ is generally concomitant with the area
  used to generate the abundance estimates in the SARs, and the abundance predicted by the same underlying density estimates is the preferred abundance to use, there is no need to separately
  compare the take to the SARs abundance estimate.
Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.
\a\ The 2020 final rule unintentionally presented this percentage as 545. The correct value is provided here. This error does not affect the conclusions in the 2020 HSTT final rule.


 Table 17--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Beaked Whales in the SOCAL Portion of the HSTT Study Area and Number Indicating the Instances of
                                                                          Total Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Instances of indicated types of incidental take (not all    Total          Abundance          Instances of total
                                                                                takes represent separate individuals, especially for      takes  ------------------------   take as percent of
                                                                                                    disturbance)                       ----------                                abundance
                                                                            -----------------------------------------------------------                                  -----------------------
                                                                                 Level B harassment          Level A                                                      Total take
                                                                            ---------------------------     harassment                    Total      Navy                     as      Total take
                  Species                                 Stock                                        -------------------                takes    abundance   NMFS SARs  percentage      as
                                                                                                                                         (entire   in action   abundance   of total   percentage
                                                                              Behavioral    TTS (may                        Mortality     study      area                    Navy      of total
                                                                             disturbance  also include   PTS     Tissue                   area)                            abundance      SAR
                                                                                          disturbance)           damage                                                    in action   abundance
                                                                                                                                                                             area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Baird's beaked whale.......................  CA/OR/WA......................        2,030            14      0           0            0     2,044          74       1,363       2,762         150
Goose-beaked whale.........................  CA/OR/WA......................       11,373           127      1           0            0    11,501         520       5,454       2,212         211

[[Page 5005]]

 
Mesoplodon species.........................  CA/OR/WA......................        6,125            68      1           0            0     6,194          89       3,044       6,960         203
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the SOCAL take estimates, because of the manner in which the Navy study area overlaps the ranges of many MMPA stocks (i.e., a stock may range far north to Washington state and beyond
  and abundance may only be predicted within the U.S. EEZ, while the Navy study area is limited to Southern California and northern Mexico, but extends beyond the U.S. EEZ), we compare
  predicted takes to both the abundance estimates for the study area, as well as the SARs (as described in the Estimated Take of Marine Mammals section of the 2018 HSTT final rule).
Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.

    Below we compile and summarize the information that supports our 
determination that the Navy's activities will not adversely affect any 
species or stocks through effects on annual rates of recruitment or 
survival for any of the affected species or stocks addressed in this 
section.
Blainville's, Goose-Beaked, and Longman's Beaked Whales (Hawaii Stocks)
    The SAR does not identify a trend for these stocks and the species 
are not listed under the ESA. No mortality or Level A harassment are 
expected or authorized for any of these three stocks. Regarding the 
magnitude of Level B harassment takes (TTS and behavioral disturbance), 
the number of estimated instances of take compared to the abundance, 
both throughout the HSTT Study Area and within the U.S. EEZ, 
respectively, is 521-544 and 514-539 percent (table 16). This 
information and the stock ranges (at least of the small, resident 
island associated stocks around Hawaii) suggest that likely a fair 
portion of the stocks (but not all) will be impacted, over 1 to perhaps 
11 days per year, with little likelihood of much take across sequential 
days. Regarding the severity of those individual Level B harassment 
takes by behavioral disturbance, the duration of any exposure is 
expected to be between minutes and hours (i.e., relatively short) and 
the received sound levels largely below 160 dB, though with beaked 
whales, which are considered somewhat more sensitive, this could mean 
that some individuals will leave preferred habitat for a day or 2 
(i.e., moderate level takes). However, while interrupted feeding bouts 
are a known response and concern for odontocetes, we also know that 
there are often viable alternative habitat options nearby. 
Additionally, as noted earlier, within the Hawaii Island mitigation 
area (which overlaps a large portion of the BIAs for goose-beaked and 
Blainville's beaked whales identified in Kratofil et al. 2023), 
explosives are not used and the use of MF1 and MF4 active sonar is 
limited, greatly reducing the severity of impacts within these two 
small resident populations.
    Regarding the severity of TTS takes, they are expected to be low-
level, of short duration, and mostly not in a frequency band that would 
be expected to interfere with beaked whale communication or other 
important low-frequency cues, and that the associated lost 
opportunities and capabilities are not at a level that will impact 
reproduction or survival.
    Altogether, a fair portion of these stocks are anticipated to be 
impacted and any individuals are likely to be disturbed at a moderate 
level, with the taken individuals likely exposed between 1 and 11 days, 
with little chance that individuals are taken across more than a few 
sequential days. This low, to occasionally moderate, magnitude and 
severity of harassment effects is not expected to result in impacts on 
individual reproduction or survival, much less have impacts on annual 
rates of recruitment or survival. For these reasons, we have 
determined, in consideration of all of the effects of the Navy's 
activities combined, that the authorized take will have a negligible 
impact on the Hawaii stocks of beaked whales.
Baird's Beaked Whale, Goose-Beaked Whale and Mesoplodon Species (All 
CA/OR/WA Stocks)
    The species are not listed under the ESA and their populations have 
been identified as ``increasing,'' ``decreasing,'' and ``increasing,'' 
respectively. No mortality is expected or authorized for any of these 
three stocks and only two takes by Level A harassment (PTS) are 
authorized.
    No methods are available to distinguish between the six species of 
Mesoplodon beaked whale CA/OR/WA stocks (Blainville's beaked whale (M. 
densirostris), Perrin's beaked whale (M. perrini), Lesser beaked whale 
(M. peruvianus), Stejneger's beaked whale (M. stejnegeri), Gingko-
toothed beaked whale (M. gingkodens), and Hubbs' beaked whale (M. 
carlhubbsi)) when observed during at-sea surveys (Carretta et al. 
2018a). Bycatch and stranding records from the region indicate that the 
Hubbs' beaked whale is most commonly encountered (Carretta et al. 2008, 
Moore and Barlow, 2013). As indicated in the SAR, no species-specific 
abundance estimates are available, the abundance estimate includes all 
CA/OR/WA Mesoplodon spp, and the six species are managed as one unit. 
Due to the lack of species-specific abundance estimates, it is not 
possible to predict the take of individual species and take estimates 
are identified as Mesoplodon spp.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance for these stocks is 2,762, 2,212, and 
6,960 percent (measured against Navy-estimated abundance) and 150, 211, 
and 203 percent (measured against the SAR) for Baird's beaked whales, 
goose-beaked beaked whales, and Mesoplodon spp., respectively (table 
17). Given the ranges of these stocks, this information suggests that 
some smaller portion of the individuals of these stocks will be taken, 
and that some subset of individuals within the stock will be taken 
repeatedly within the year (perhaps up to 20-25 days, and potentially 
more for goose-beaked)--

[[Page 5006]]

potentially over a fair number of sequential days, especially where 
individuals spend extensive time in the SOCAL Range. Note that we 
predict lower days of repeated exposure for these stocks than their 
percentages might have suggested because of the number of overall 
takes--i.e., using the higher percentage would suggest that an unlikely 
portion of the takes are taken up by a small portion of the stock 
incurring a very large number of repeat takes, with little room for 
take resulting from few or moderate numbers of repeats, which is 
unlikely. While interrupted feeding bouts are a known response and 
concern for odontocetes, we also know that there are often viable 
alternative habitat options in the relative vicinity. Regarding the 
severity of those individual Level B harassment takes by behavioral 
disturbance, we have explained that the duration of any exposure is 
expected to be between minutes and hours (i.e., relatively short) and 
the received sound levels largely below 160 dB, though with beaked 
whales, which are considered somewhat more sensitive, this could mean 
that some individuals will leave preferred habitat for a day or 2 
(i.e., of a moderate level). In addition, as noted, some of these takes 
could occur on a fair number of sequential days for these stocks.
    The severity of TTS takes is expected to be low-level, of short 
duration, and mostly not in a frequency band that would be expected to 
interfere significantly with conspecific communication, echolocation, 
or other important low-frequency cues. Therefore, the associated lost 
opportunities and capabilities are not expected to impact reproduction 
or survival. For similar reasons (as described in the 2020 HSTT final 
rule) the single estimated Level A harassment take by PTS for this 
stock is unlikely to have any effects on the reproduction or survival 
of any individuals.
    Altogether, a portion of these stocks will likely be taken (at a 
moderate or sometimes low level) over several days a year, and some 
smaller portion of the stock is expected to be taken on a relatively 
moderate to high number of days across the year, some of which could be 
sequential days. Though the majority of impacts are expected to be of a 
moderate severity, the repeated takes over a potentially fair number of 
sequential days for some individuals makes it more likely that a small 
number of individuals could be interrupted during foraging in a manner 
and amount such that impacts to the energy budgets of females (from 
either losing feeding opportunities or expending considerable energy to 
find alternative feeding options) could cause them to forego 
reproduction for a year. Energetic impacts to males are generally 
meaningless to population rates unless they cause death, and it takes 
extreme energy deficits beyond what would ever be likely to result from 
these activities to cause the death of an adult marine mammal. As noted 
previously, however, foregone reproduction (especially for 1 year, 
which is the maximum predicted because the small number anticipated in 
any 1 year makes the probability that any individual would be impacted 
in this way twice in 7 years very low) has far less of an impact on 
population rates than mortality and a small number of instances of 
foregone reproduction are not expected to adversely affect these stocks 
through effects on annual rates of recruitment or survival, especially 
given the residual PBR of these three beaked whale stocks (8.7, 41.9, 
and 19.9, respectively).
    Further, Navy activities have been conducted in SOCAL for many 
years at similar levels and the SAR considers Mesoplodon spp. and 
Baird's beaked whales as increasing. While NMFS' SAR indicates that 
goose-beaked whales on the U.S. West Coast are declining based on a 
Bayesian trend analysis of NMFS' survey data collected from 1991 
through 2014, results from passive acoustic monitoring and other 
research have estimated regional goose-beaked whale densities that were 
higher than indicated by NMFS' broad-scale visual surveys for the U.S. 
West Coast (Debich et al. 2015a; Debich et al. 2015b; Falcone and 
Schorr, 2012, 2014; Hildebrand et al. 2009; Moretti, 2016; 
[Scaron]irovi[cacute] et al. 2016; Smultea and Jefferson, 2014). 
Research also indicates higher than expected residency in the Navy's 
instrumented Southern California Anti-Submarine Warfare Range in 
particular (Falcone and Schorr, 2012) and photo identification studies 
in the SOCAL have identified approximately 100 individual goose-beaked 
whale individuals with 40 percent having been seen in one or more prior 
years, with re-sightings up to 7 years apart (Falcone and Schorr, 
2014). The documented residency by many goose-beaked whales over 
multiple years suggests that a stable population may exist in that 
small portion of the stock's overall range (Falcone et al. 2009; 
Falcone and Schorr, 2014; Schorr et al. 2017).
    For these reasons, in consideration of all of the effects of the 
Navy's activities combined, we have determined that the authorized take 
will have a negligible impact on the CA/OR/WA stocks of Baird's and 
goose-beaked whales, as well as all six species included within the 
Mesoplodon spp.

Small Whales and Dolphins

    In tables 18 and 19 below for dolphins and small whales, we 
indicate the total annual mortality, Level A and Level B harassment, 
and a number indicating the instances of total take as a percentage of 
abundance. Tables 18 and 19 are updated from tables 24 and 25 in the 
2020 HSTT final rule as appropriate with the 2023 final SARs. For 
additional information and analysis supporting the negligible-impact 
analysis, see the Odontocetes discussion as well as the Small Whales 
and Dolphins discussion in the Group and Species-Specific Analyses 
section of the 2018 HSTT final rule, all of which remains applicable to 
this rule unless specifically noted.

   Table 18--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Dolphins and Small Whales in the HRC Portion of the HSTT Study Area and Number Indicating the
                                                                   Instances of Total Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Instances of indicated types of incidental take (not all      Total takes            Abundance        Instance of total take
                                                                      takes represent separate individuals, especially for   --------------------------------------------      as percent of
                                                                                          disturbance)                                                                           abundance
                                                                   ----------------------------------------------------------                                            -----------------------
                                                                        Level B harassment          Level A                     Total             Total Navy              Total take   EEZ take
                Species                            Stock           ---------------------------    harassment                    takes     Takes    abundance  Within EEZ      as          as
                                                                                              ------------------               (entire   (within  inside and     Navy     percentage  percentage
                                                                                   TTS (may                       Mortality     study     Navy    outside of   abundance   of total     of Navy
                                                                     Behavioral  also include           Tissue                  area)     EEZ)     EEZ (HRC)     (HRC)       Navy         EEZ
                                                                    disturbance  disturbance)   PTS     damage                                                             abundance   abundance
                                                                                                                                                                             (HRC)       (HRC)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Bottlenose dolphin.....................  Hawaii Pelagic...........        3,196           132      0          0            0     3,328     2,481       1,528       1,442         218         172

[[Page 5007]]

 
Bottlenose dolphin.....................  Kauai & Niihau...........          534            31      0          0            0       565       264         184         184         307         143
Bottlenose dolphin.....................  Oahu.....................        8,600            61      1          0            0     8,662     8,376         743         743   \a\ 1,166   \a\ 1,127
Bottlenose dolphin.....................  4-Island.................          349            10      0          0            0       359       316         189         189         190         167
Bottlenose dolphin.....................  Hawaii...................           74             6      0          0            0        80        42         131         131          61          32
False killer whale.....................  Hawaii Pelagic...........          999            42      0          0            0     1,041       766         645         507         161         151
False killer whale.....................  Main Hawaiian Islands              572            17      0          0            0       589       476         147         147     \b\ 401         324
                                          Insular.
False killer whale.....................  Northwestern Hawaiian              365            16      0          0            0       381       280         215         169         177         166
                                          Islands.
Fraser's dolphin.......................  Hawaii...................       39,784         1,289      2          0            0    41,075    31,120       5,408      18,763         760         166
Killer whale...........................  Hawaii...................          118             6      0          0            0       124        93          69          54         180         172
Melon-headed whale.....................  Hawaii Islands...........        3,261           231      0          0            0     3,492     2,557       1,782       1,782         196         143
Melon-headed whale.....................  Kohala Resident..........          341             9      0          0            0       350       182         447         447          78          41
Pantropical spotted dolphin............  Hawaii Island............        3,767           227      0          0            0     3,994     2,576       2,405       2,405         166         107
Pantropical spotted dolphin............  Hawaii Pelagic...........        9,973           476      0          0            0    10,449     7,600       5,462       4,637         191         164
Pantropical spotted dolphin............  Oahu.....................        4,284            45      0          0            0     4,329     4,194         372         372       1,164       1,127
Pantropical spotted dolphin............  4-Island.................          701            17      0          0            0       718       634         657         657         109          96
Pygmy killer whale.....................  Hawaii...................        8,122           402      0          0            0     8,524     6,538       4,928       3,931         173         166
Pygmy killer whale.....................  Tropical.................          710            50      0          0            0       760       490         159          23         478       2,130
Risso's dolphin........................  Hawaii...................        8,950           448      0          0            0     9,398     7,318       1,210       4,199         777         174
Rough-toothed dolphin..................  Hawaii...................        6,112           373      0          0            0     6,485     4,859       3,054       2,808         212         173
Short-finned pilot whale...............  Hawaii...................       12,499           433      0          0            0    12,932     9,946       6,433       5,784         201         172
Spinner dolphin........................  Hawaii Island............          279            12      0          0            0       291        89         629         629          46          14
Spinner dolphin........................  Hawaii Pelagic...........        4,332           202      0          0            0     4,534     3,491       2,885       2,229         157         157
Spinner dolphin........................  Kauai & Niihau...........        1,683            63      0          0            0     1,746       812         604         604         289         134
Spinner dolphin........................  Oahu & 4-Island..........        1,790            34      1          0            0     1,825     1,708         354         354         516         482
Striped dolphin........................  Hawaii...................        7,379           405      0          0            0     7,784     6,034       4,779       3,646         163         165
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the Hawaii take estimates, we compare predicted takes to abundance estimates generated from the same underlying density estimates (as described in the Estimated Take of Marine
  Mammals section of the 2018 HSTT final rule), both in and outside of the U.S. EEZ. Because the portion of the Navy's study area inside the U.S. EEZ is generally concomitant with the area
  used to generate the abundance estimates in the SARs, and the abundance predicted by the same underlying density estimates is the preferred abundance to use, there is no need to separately
  compare the take to the SARs abundance estimate.
Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.

[[Page 5008]]

 
\a\ The 2020 final rule unintentionally presented these percentages as 1,169 and 1,130. The correct values are provided here. These errors do not affect the conclusions in the 2020 HSTT final
  rule.
\b\ The 2020 final rule unintentionally presented this percentage as 400. The correct value is provided here. This rounding error does not affect the conclusions in the 2020 HSTT final rule.


  Table 19--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Dolphins and Small Whales in the SOCAL Portion of the HSTT Study Area and Number Indicating the
                                                                   Instances of Total Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Instances of indicated types of incidental take (not   Total takes         Abundance        Instance of total take
                                                                              all takes represent separate individuals, especially  -------------------------------------      as percent of
                                                                                                for disturbance)                                                                 abundance
                                                                           ---------------------------------------------------------                                     -----------------------
                                                                                Level B harassment         Level A                                                        Total take
                                                                           ---------------------------    harassment                                 Navy                     as      Total take
                  Species                                Stock                                        -----------------              Total takes   abundance   NMFS SARs  percentage      as
                                                                                                                                       (entire     in action   abundance   of total   percentage
                                                                             Behavioral    TTS (may                      Mortality   study area)     area                    Navy      of total
                                                                            disturbance  also include   PTS    Tissue                               (SOCAL)                abundance      SAR
                                                                                         disturbance)          damage                                                      in action   abundance
                                                                                                                                                                             area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Bottlenose dolphin.........................  California Coastal...........        1,771            38      0         0            0        1,809         238         453         760         399
Bottlenose dolphin.........................  CA/OR/WA Offshore............       51,727         3,695      3         0            0       55,425       5,946       3,477         932       1,594
Killer whale...............................  ENP Offshore.................           96            11      0         0            0          107           4         300       2,675          36
Killer whale...............................  ENP Transient/West Coast               179            20      0         0            0          199          30         349         663          57
                                              Transient.
Long-beaked common dolphin.................  California...................      233,485        13,787     18         2            0      247,292      10,258      83,379       2,411         297
Northern right whale dolphin...............  CA/OR/WA.....................       90,052         8,047     10         1            0       98,110       7,705      29,285       1,273         335
Pacific white-sided dolphin................  CA/OR/WA.....................       69,245         6,093      5         0            0       75,343       6,626      34,999       1,137         215
Risso's dolphin............................  CA/OR/WA.....................      116,143        10,118      9         0            0      126,270       7,784       6,336       1,622       1,993
Short-beaked common dolphin................  CA/OR/WA.....................    1,374,048       118,525     79        10         1.14    1,492,664     261,438   1,056,308         571         141
Short-finned pilot whale...................  CA/OR/WA.....................        1,789           124      1         0            0        1,914         208         836         920         229
Striped dolphin............................  CA/OR/WA.....................      163,640        11,614      3         0            0      175,257      39,862      29,988         440         584
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the SOCAL take estimates, because of the manner in which the Navy study area overlaps the ranges of many MMPA stocks (i.e., a stock may range far north to Washington state and beyond
  and abundance may only be predicted within the U.S. EEZ, while the Navy study area is limited to Southern California and northern Mexico, but extends beyond the U.S. EEZ), we compare
  predicted takes to both the abundance estimates for the study area, as well as the SARs (as described in the Estimated Take of Marine Mammals section of the 2018 HSTT final rule).
Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.
For mortality takes there is an annual average of 1.14 short-beaked common dolphins (i.e., where eight takes could potentially occur divided by 7 years to get the annual number of mortalities/
  serious injuries).

    Below we compile and summarize the information that supports our 
determination that the Navy's activities will not adversely affect any 
species or stocks through effects on annual rates of recruitment or 
survival for any of the affected species or stocks addressed in this 
section.
Long-Beaked Common Dolphin (California Stock), Northern Right Whale 
Dolphin (CA/OR/WA Stock), and Short-Beaked Common Dolphin (CA/OR/WA 
Stock)
    None of these stocks are listed under the ESA and their stock 
statuses are considered ``increasing,'' ``unknown,'' and 
``increasing,'' respectively. Eight mortalities or serious injuries of 
short-beaked common dolphins are authorized over the 7-year rule, or 
1.14 M/SI annually. The addition of this 1.14 annual mortality still 
leaves the total human-caused mortality well under the insignificance 
threshold for residual PBR. The 3 stocks are expected to accrue 2, 1, 
and 10 Level A harassment takes from tissue damage resulting from 
exposure to explosives, respectively. As described in detail in the 
2018 HSTT final rule, the impacts of a Level A harassment take by 
tissue damage could range in impact from minor to something just less 
than M/SI that could seriously impact fitness. However, given the 
Navy's procedural mitigation, exposure closer to the source and more 
severe end of the spectrum is less likely and we cautiously assume some 
moderate impact for these takes that could lower the affected 
individual's fitness within the year such that a female (assuming a 50 
percent chance of it being a female) might forego reproduction for 1 
year. As noted previously, foregone reproduction has less of an impact 
on population rates than death (especially for only 1 year in 7, which 
is the maximum predicted because the small number anticipated in any 1 
year makes the probability that any individual would be impacted in 
this way twice in 7 years very low), and 1 to 10 instances would not be 
expected to impact annual rates of recruitment or survival for these 
stocks.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is 2,411, 1,273, and 571 percent 
(respective to the stocks listed in the heading) and 297, 335, and 141 
percent (respective to the stocks listed in the heading) (table 19). 
Given the range of these stocks, this information suggests that likely 
some portion (but not all or even the majority) of the individuals in 
the northern right whale dolphin and short-beaked common dolphin stocks 
are likely impacted while it is entirely possible that most or all of 
the range-limited long-beaked common dolphin is

[[Page 5009]]

taken. All three stocks likely will experience some repeat Level B 
harassment exposure (perhaps up to 48, 25, or 11 days within a year, 
respective to the stocks listed in the heading) of some subset of 
individuals that spend extended time within the SOCAL range complex. 
While interrupted feeding bouts are a known response and concern for 
odontocetes, we also know that there are often viable alternative 
habitat options in the relative vicinity. Regarding the severity of 
those individual Level B harassment takes by behavioral disturbance, 
the duration of any exposure is expected to be between minutes and 
hours (i.e., relatively short) and the received sound levels largely 
below 172 dB with a portion up to 178 dB (i.e., of a moderate or lower 
level, less likely to evoke a severe response). However, some of these 
takes could occur on a fair number of sequential days for long-beaked 
common dolphins or northern right whale dolphins, or even some number 
of short-beaked common dolphins, given the high number of total takes 
(i.e., the probability that some number of individuals get taken on a 
higher number of sequential days is higher, because the total take 
number is relatively high, even though the percentage is not that 
high).
    The severity of TTS takes is expected to be low-level, of short 
duration, and mostly not in a frequency band that would be expected to 
interfere significantly with conspecific communication, echolocation, 
or other important low-frequency cues, and the associated lost 
opportunities and capabilities are not expected to impact reproduction 
or survival. For these same reasons (low level and frequency band), 
while a small permanent loss of hearing sensitivity may include some 
degree of energetic costs for compensating or may mean some small loss 
of opportunities or detection capabilities, as discussed in the 2020 
HSTT final rule, it is unlikely to impact behaviors, opportunities, or 
detection capabilities to a degree that would interfere with 
reproductive success or survival of any individuals.
    Altogether and as described in more detail above, 1.14 annual 
lethal takes of short-beaked common dolphins are authorized, all three 
stocks may experience a very small number of takes by tissue damage or 
PTS (relative to the stock abundance and PBR), and a moderate to large 
portion of all three stocks will likely be taken (at a low to 
occasionally moderate level) over several days a year, and some smaller 
portion of these stocks is expected to be taken on a relatively 
moderate to high number of days across the year, some of which could be 
sequential days. Though the majority of impacts are expected to be of a 
lower to sometimes moderate severity, the larger number of takes (in 
total and for certain individuals) makes it more likely 
(probabilistically) that a small number of individuals could be 
interrupted during foraging in a manner and amount such that impacts to 
the energy budgets of females (from either losing feeding opportunities 
or expending considerable energy to find alternative feeding options) 
could cause them to forego reproduction for a year. Energetic impacts 
to males are generally meaningless to population rates unless they 
cause death, and it takes extreme energy deficits beyond what would 
ever be likely to result from these activities to cause the death of an 
adult marine mammal. As noted previously, however, foregone 
reproduction (especially for only 1 year out of 7, which is the maximum 
predicted because the small number anticipated in any 1 year makes the 
probability that any individual would be impacted in this way twice in 
7 years very low) has far less of an impact on population rates than 
mortality and a small number of instances of foregone reproduction 
(including in combination with that which might result from the small 
number of tissue damage takes) are not expected to adversely affect the 
stocks through effects on annual rates of recruitment or survival, 
especially given the very high residual PBRs of these stocks (638.3, 
156.4, and 8,858.5, respectively). For these reasons, in consideration 
of all of the effects of the Navy's activities combined (mortality, 
Level A harassment, and Level B harassment), we have determined that 
the authorized take will have a negligible impact on these three stocks 
of dolphins.
All Other SOCAL Dolphin Stocks (Except Long-Beaked Common Dolphin, 
Northern Right Whale Dolphin, and Short-Beaked Common Dolphin)
    None of these stocks are listed under the ESA and their stock 
statuses are considered ``unknown,'' except for the bottlenose dolphin 
(California coastal stock) and killer whale (Eastern North Pacific 
stock), which are considered ``stable.'' No M/SI or Level A harassment 
via tissue damage from exposure to explosives is expected or authorized 
for these stocks.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is from 440 to 2,675 percent and 36 to 
1,993 percent, respectively (table 19). Given the range of these stocks 
(along the entire U.S. West Coast, or even beyond, with some also 
extending seaward of the HSTT Study Area boundaries), this information 
suggests that some portion (but not all or even the majority) of the 
individuals of any of these stocks will be taken, with the exception 
that most or all of the individuals of the more range-limited 
California coastal stock of bottlenose dolphin may be taken. It is also 
likely that some subset of individuals within most of these stocks will 
be taken repeatedly within the year (perhaps up to 10-15 days within a 
year) but with no more than several potentially sequential days, 
although the CA/OR/WA stocks of bottlenose dolphins, Pacific white-
sided dolphins, and Risso's dolphins may include individuals that are 
taken repeatedly within the year over a higher number of days (up to 
57, 22, and 40 days, respectively) and potentially over a fair number 
of sequential days, especially where individuals spend extensive time 
in the SOCAL range complex. Note that though percentages are high for 
the Eastern North Pacific stock of killer whales and short-finned pilot 
whales, given the low overall number of takes, it is highly unlikely 
that any individuals would be taken across the number of days their 
percentages would suggest. While interrupted feeding bouts are a known 
response and concern for odontocetes, we also know that there are often 
viable alternative habitat options in the relative vicinity. Regarding 
the severity of those individual Level B harassment takes by behavioral 
disturbance, we have explained that the duration of any exposure is 
expected to be between minutes and hours (i.e., relatively short) and 
the received sound levels largely below 172 dB (i.e., of a lower, or 
sometimes moderate level, less likely to evoke a severe response). 
However, as noted, some of these takes could occur on a fair number of 
sequential days for the three stocks listed earlier.
    The severity of TTS takes is expected to be low-level, of short 
duration, and mostly not in a frequency band that would be expected to 
interfere significantly with conspecific communication, echolocation, 
or other important low-frequency cues. For these same reasons (low 
level and frequency band), while a small permanent loss of hearing 
sensitivity may include some degree of energetic costs for compensating 
or may mean some small loss of opportunities or detection capabilities, 
it is unlikely to impact

[[Page 5010]]

behaviors, opportunities, or detection capabilities to a degree that 
would interfere with reproductive success or survival of any 
individuals.
    Altogether, a portion of all of these stocks will likely be taken 
(at a low to occasionally moderate level) over several days a year, and 
some smaller portion of CA/OR/WA stocks of bottlenose dolphins, Pacific 
white-sided dolphins, and Risso's dolphins, specifically, are expected 
to be taken on a relatively moderate to high number of days across the 
year, some of which could be sequential days. Though the majority of 
impacts are expected to be of a lower to sometimes moderate severity, 
the larger number of takes (in total and for certain individuals) for 
the CA/OR/WA stocks of bottlenose dolphins, Pacific white-sided 
dolphins, and Risso's dolphins makes it more likely (probabilistically) 
that a small number of individuals could be interrupted during foraging 
in a manner and amount such that impacts to the energy budgets of 
females (from either losing feeding opportunities or expending 
considerable energy to find alternative feeding options) could cause 
them to forego reproduction for a year. Energetic impacts to males are 
generally meaningless to population rates unless they cause death, and 
it takes extreme energy deficits beyond what would ever be likely to 
result from these activities to cause the death of an adult marine 
mammal. As noted previously, however, foregone reproduction (especially 
for only 1 year in 7, which is the maximum predicted because the small 
number anticipated in any 1 year makes the probability that any 
individual would be impacted in this way twice in 7 years very low) has 
far less of an impact on population rates than mortality and a small 
number of instances of foregone reproduction are not expected to 
adversely affect the stocks through effects on annual rates of 
recruitment or survival, especially given the residual PBRs of the CA/
OR/WA stocks of bottlenose dolphins, Pacific white-sided dolphins, and 
Risso's dolphins (18.9, 272, and 42.3, respectively). For these 
reasons, in consideration of all of the effects of the Navy's 
activities combined, we have determined that the authorized take will 
have a negligible impact on these stocks of dolphins.
All HRC Dolphin Stocks
    With the exception of the Main Hawaiian Island stock of false 
killer whales (listed as endangered under the ESA, with the MMPA stock 
identified as ``decreasing''), none of these stocks are listed under 
the ESA and their stock statuses are considered ``unknown.'' No M/SI or 
Level A harassment via tissue damage from exposure to explosives is 
expected or authorized for these stocks.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is from 46 to 1,166 percent and 14 to 
2,130 percent, respectively (table 18). Given the ranges of these 
stocks (many of them are small, resident, island-associated stocks), 
this information suggests that a fairly large portion of the 
individuals of many of these stocks will be taken but that most 
individuals will only be impacted across a smaller to moderate number 
of days within the year (1-15), and with no more than several 
potentially sequential days, although two stocks (the Oahu stocks of 
bottlenose dolphin and pantropical spotted dolphin) have a slightly 
higher percentage, suggesting they could be taken up to 23 days within 
a year, with perhaps a few more of those days being sequential. We note 
that although the percentage is higher for the tropical stock of pygmy 
killer whale within the U.S. EEZ (2,130), given (1) the low overall 
number of takes (760) and (2) the fact that the small within-U.S. EEZ 
abundance is not a static set of individuals, but rather individuals 
moving in and out of the U.S. EEZ making it more appropriate to use the 
percentage comparison for the total takes versus total abundance--it is 
highly unlikely that any individuals would be taken across the number 
of days the within-U.S. EEZ percentage suggests (42). While interrupted 
feeding bouts are a known response and concern for odontocetes, we also 
know that there are often viable alternative habitat options in the 
relative vicinity. Regarding the severity of those individual Level B 
harassment takes by behavioral disturbance, the duration of any 
exposure is expected to be between minutes and hours (i.e., relatively 
short) and the received sound levels largely below 172 dB (i.e., of a 
lower, or sometimes moderate level, less likely to evoke a severe 
response). However, as noted, some of these takes could occur on a fair 
number of sequential days for the Oahu stocks of bottlenose dolphin and 
pantropical spotted dolphins.
    Within the Hawaii Island mitigation area (which overlaps a large 
portion of the BIAs for common bottlenose dolphin, dwarf sperm whale, 
false killer whale, melon-headed whale, pantropical spotted dolphin, 
pygmy killer whale, rough-toothed dolphin, short-finned pilot whale, 
and spinner dolphin identified in Kratofil et al. 2023), the Navy will 
not use explosives and will limit the use of MF1 and MF4 active sonar. 
The 4-Islands mitigation area overlaps a portion of the BIAs identified 
in Kratofil et al. (2023) for common bottlenose dolphin, false killer 
whale, pantropical spotted dolphin, rough-toothed dolphin, and spinner 
dolphin. Within the 4-Islands mitigation area (November 15-April 15), 
the Navy will not use MF1 surface ship hull-mounted mid-frequency 
active sonar or explosives that could potentially result in takes of 
marine mammals. The mitigation required in these two areas will reduce 
the severity of impacts within these small and resident populations.
    Regarding the severity of TTS takes, they are expected to be low-
level, of short duration, and mostly not in a frequency band that would 
be expected to interfere significantly with conspecific communication, 
echolocation, or other important low-frequency cues. For these same 
reasons (low level and frequency band), while a small permanent loss of 
hearing sensitivity may include some degree of energetic costs for 
compensating or may mean some small loss of opportunities or detection 
capabilities, they are unlikely to impact behaviors, opportunities, or 
detection capabilities to a degree that would interfere with 
reproductive success or survival of any individuals, even if accrued to 
individuals that are also taken by behavioral harassment at the same 
time.
    Altogether, most of these stocks (all but the Oahu stocks of 
bottlenose dolphin and pantropical spotted dolphins) will likely be 
taken (at a low to occasionally moderate level) over several days a 
year, with some smaller portion of the stock potentially taken on a 
more moderate number of days across the year (perhaps up to 15 days for 
Fraser's dolphin, though others notably less), some of which could be 
across a few sequential days, which is not expected to affect the 
reproductive success or survival of individuals. For the Oahu stocks of 
bottlenose dolphin and pantropical spotted dolphins, some subset of 
individuals could be taken up to 23 days in a year, with some small 
number being taken across several sequential days, such that a small 
number of individuals could be interrupted during foraging in a manner 
and amount such that impacts to the energy budgets of females (from 
either losing feeding opportunities or expending considerable energy to 
find alternative feeding options) could cause them to forego 
reproduction for a year. Energetic impacts to males are generally 
meaningless to population rates unless

[[Page 5011]]

they cause death, and it takes extreme energy deficits beyond what 
would ever be likely to result from these activities to cause the death 
of an adult marine mammal. As noted previously, however, foregone 
reproduction (especially for 1 year, which is the maximum predicted 
because the small number anticipated in any 1 year makes the 
probability that any individual would be impacted in this way twice in 
7 years very low) has far less of an impact on population rates than 
mortality and a small number of instances of foregone reproduction are 
not expected to adversely affect these two stocks through effects on 
annual rates of recruitment or survival. For these reasons, in 
consideration of all of the effects of the Navy's activities combined, 
we have determined that the authorized take will have a negligible 
impact on all of the stocks of dolphins found in the vicinity of the 
HRC.

Dall's Porpoise

    In table 20 below for porpoises, we indicate the total annual 
mortality, Level A harassment and Level B harassment, and a number 
indicating the instances of total take as a percentage of abundance. 
Table 20 is updated from table 26 in the 2020 HSTT final rule with the 
2023 final SARs. For additional information and analysis supporting the 
negligible-impact analysis, see the Odontocetes discussion as well as 
the Dall's Porpoise discussion in the Group and Species-Specific 
Analyses section of the 2018 HTT final rule, all of which remains 
applicable to this rule unless specifically noted.

Table 20--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Porpoises in the HSTT Study Area and Number Indicating the Instances of Total Take as a Percentage
                                                                                       of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Instances of indicated types of incidental take (not all    Total          Abundance          Instances of total
                                                                                takes represent separate individuals, especially for      takes  ------------------------   take as percent of
                                                                                                    disturbance)                       ----------                                abundance
                                                                            -----------------------------------------------------------                                  -----------------------
                                                                                 Level B harassment          Level A                                                      Total take
                                                                            ---------------------------     harassment                    Total      Navy                     as      Total take
                  Species                                 Stock                                        -------------------                takes    abundance   NMFS SARs  percentage      as
                                                                                                                                         (entire   in Action   abundance   of total   percentage
                                                                              Behavioral    TTS (may                        Mortality     study      Area                    Navy      of total
                                                                             disturbance  also include   PTS     Tissue                   area)                            abundance      SAR
                                                                                          disturbance)           damage                                                    in Action   abundance
                                                                                                                                                                             Area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Dall's porpoise............................  CA/OR/WA......................       14,482        29,891    209           0            0    44,582       2,054      16,498       2,170         270
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the SOCAL take estimates, because of the manner in which the Navy study area overlaps the ranges of many MMPA stocks (i.e., a stock may range far north to Washington state and beyond
  and abundance may only be predicted within the U.S. EEZ, while the Navy study area is limited to Southern California and northern Mexico, but extends beyond the U.S. EEZ), we compare
  predicted takes to both the abundance estimates for the study area, as well as the SARs (as described in the Estimated Take of Marine Mammals section of the 2018 HSTT final rule).
Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.

    Below we compile and summarize the information that supports our 
determination that the Navy's activities will not adversely affect 
Dall's porpoises through effects on annual rates of recruitment or 
survival.
    Dall's porpoise is not listed under the ESA and the stock status is 
considered ``unknown.'' No M/SI or Level A harassment via tissue damage 
from exposure to explosives is expected or authorized for this stock.
    Most Level B harassments to Dall's porpoise from hull-mounted sonar 
(MF1) in the HSTT Study Area will result from received levels between 
154 and 166 dB SPL (85 percent). While harbor porpoises have been 
observed to be especially sensitive to human activity, the same types 
of responses have not been observed in Dall's porpoises. Dall's 
porpoises are typically notably longer than and weigh more than twice 
as much as harbor porpoises making them generally less likely to be 
preyed upon and likely differentiating their behavioral repertoire 
somewhat from harbor porpoises. Further, they are typically seen in 
large groups and feeding aggregations or exhibiting bow-riding 
behaviors, which is very different from the group dynamics observed in 
the more typically solitary, cryptic harbor porpoises, which are not 
often seen bow-riding. For these reasons, Dall's porpoises are not 
treated as especially sensitive species (as compared to harbor 
porpoises, which have a lower threshold for Level B harassment by 
behavioral disturbance and more distant cutoff) but, rather, are 
analyzed similarly to other odontocetes. Therefore, the majority of 
Level B harassment takes are expected to be in the form of milder 
responses compared to higher level exposures. As discussed more fully 
in the 2018 HSTT final rule, we anticipate more severe effects from 
takes when animals are exposed to higher received levels.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), the number of estimated total instances of 
take compared to the abundance (measured against both the Navy-
estimated abundance and the SAR) is 2,170 and 270 percent, respectively 
(table 20). Given the range of this stock (up the U.S. West Coast 
through Washington and sometimes beyond the U.S. EEZ), this information 
suggests that some smaller portion of the individuals of this stock 
will be taken, and that some subset of individuals within the stock 
will be taken repeatedly within the year (perhaps up to 42 days)--
potentially over a fair number of sequential days, especially where 
individuals spend extensive time in the SOCAL range complex. While 
interrupted feeding bouts are a known response and concern for 
odontocetes, we also know that there are often viable alternative 
habitat options in the relative vicinity. Regarding the severity of 
those individual Level B harassment takes by behavioral disturbance, 
the duration of any exposure is expected to be between minutes and 
hours (i.e., relatively short) and the received sound levels largely 
below 172 dB (i.e., of a lower, or sometimes moderate level, less 
likely to evoke a severe response). However, as noted, some of these 
takes could occur on a fair number of sequential days for this stock.
    The severity of TTS takes is expected to be low-level, of short 
duration, and mostly not in a frequency band that would be expected to 
interfere significantly with conspecific communication, echolocation, 
or other important low-frequency cues. Therefore, the associated lost 
opportunities and capabilities are not expected to impact reproduction 
or survival. For these same reasons (low level and the likely frequency 
band), while a small permanent loss of hearing sensitivity may include 
some degree of energetic costs for compensating or may

[[Page 5012]]

mean some small loss of opportunities or detection capabilities, the 
estimated 209 takes by Level A harassment by PTS for Dall's porpoise 
are unlikely to impact behaviors, opportunities, or detection 
capabilities to a degree that would interfere with reproductive success 
or survival for most individuals. Because of the high number of PTS 
takes, however, we acknowledge that a few animals could potentially 
incur permanent hearing loss of a higher degree that could potentially 
interfere with their successful reproduction and growth. Given the 
status of the stock, even if this occurred, it would not adversely 
impact rates of recruitment or survival.
    Altogether, a portion of this stock will likely be taken (at a low 
to occasionally moderate level) over several days a year, and some 
smaller portion of the stock is expected to be taken on a relatively 
moderate to high number of days across the year, some of which could be 
sequential days. Though the majority of impacts are expected to be of a 
lower to sometimes moderate severity, the larger number of takes (in 
total and for certain individuals) for the Dall's porpoise makes it 
more likely (probabilistically) that a small number of individuals 
could be interrupted during foraging in a manner and amount such that 
impacts to the energy budgets of females (from either losing feeding 
opportunities or expending considerable energy to find alternative 
feeding options) could cause them to forego reproduction for a year. 
Energetic impacts to males are generally meaningless to population 
rates unless they cause death, and it takes extreme energy deficits 
beyond what would ever be likely to result from these activities to 
cause the death of an adult marine mammal. Similarly, we acknowledge 
the potential for this to occur to a few individuals out of the 209 
total that might incur a higher degree of PTS. As noted previously, 
however, foregone reproduction (especially for only 1 year in 7, which 
is the maximum predicted because the small number anticipated in any 1 
year makes the probability that any individual would be impacted in 
this way twice in 7 years very low) has far less of an impact on 
population rates than mortality. Further, the small number of instances 
of foregone reproduction that could potentially result from PTS and/or 
the few repeated, more severe Level B harassment takes by behavioral 
disturbance are not expected to adversely affect the stock through 
effects on annual rates of recruitment or survival, especially given 
the status of the species (not endangered or threatened; minimum 
population of 10,286 just within the U.S. EEZ) and residual PBR of 
Dall's porpoise (98.3). For these reasons, in consideration of all of 
the effects of the Navy's activities combined, we have determined that 
the authorized take will have a negligible impact on Dall's porpoise.

Pinnipeds

    In tables 21 and 22 below for pinnipeds, we indicate the total 
annual mortality, Level A harassment and Level B harassment, and a 
number indicating the instances of total take as a percentage of 
abundance. Tables 21 and 22 have been updated from tables 27 and 28 in 
the 2020 HSTT final rule with the 2023 final SARs. For additional 
information and analysis supporting the negligible-impact analysis, see 
the Pinnipeds discussion in the Group and Species-Specific Analyses 
section of the 2018 HSTT final rule, all of which remains applicable to 
this rule unless specifically noted.

 Table 21--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Pinnipeds in the HRC Portion of the HSTT Study Area and Number Indicating the Instances of Total
                                                                             Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Instances of indicated types of incidental take (not all takes represent        Total takes              Abundance        Instance of total take
                                                           separate individuals, especially for disturbance)              -----------------------------------------------      as percent of
                                             -----------------------------------------------------------------------------                                                       abundance
                                                           Level B harassment                    Level A                                                                 -----------------------
                                             ----------------------------------------------     harassment                                        Total Navy              Total take   EEZ take
                   Species                                                                 -------------------             Total takes    Takes    abundance  Within EEZ      as          as
                                                                                                                              (entire    (within  inside and     Navy     percentage  percentage
                                                                                TTS (may                        Mortality  study area)    Navy    outside of   abundance   of total     of Navy
                                                  Behavioral disturbance      also include   PTS     Tissue                               EEZ)    EEZ  (HRC)     (HRC)       Navy         EEZ
                                                                              disturbance)           damage                                                                abundance   abundance
                                                                                                                                                                             (HRC)       (HRC)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Hawaiian monk seal..........................  143...........................            62      1           0           0          206       195         169         169         122         115
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the Hawaii take estimates, we compare predicted takes to abundance estimates generated from the same underlying density estimates (as described in the Estimated Take of Marine
  Mammals section of the 2018 HSTT final rule), both in and outside of the U.S. EEZ. Because the portion of the Navy's study area inside the U.S. EEZ is generally concomitant with the area
  used to generate the abundance estimates in the SARs, and the abundance predicted by the same underlying density estimates is the preferred abundance to use, there is no need to separately
  compare the take to the SARs abundance estimate.
Total takes inside and outside U.S. EEZ represent the sum of annual Level A and Level B harassment from training and testing activities.


Table 22--Annual Estimated Takes by Level B Harassment, Level A Harassment, and Mortality for Pinnipeds in the SOCAL Portion of the HSTT Study Area and Number Indicating the Instances of Total
                                                                             Take as a Percentage of Stock Abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Instances of indicated types of incidental take  (not all    Total          Abundance        Instance of total take
                                                                                takes represent separate individuals, especially for      Takes  ------------------------      as percent of
                                                                                                    disturbance)                       ----------                                abundance
                                                                            -----------------------------------------------------------                                  -----------------------
                                                                                 Level B harassment          Level A                                                      Total take
                                                                            ---------------------------     harassment                    Total      Navy                     as      Total take
                  Species                                 Stock                                        -------------------                takes    abundance   NMFS SARs  percentage      as
                                                                                                                                         (entire   in action   abundance   of total   percentage
                                                                              Behavioral    TTS  (may                       Mortality     study      area                    Navy      of total
                                                                             disturbance  also include   PTS     Tissue                   area)     (SOCAL)                abundance      SAR
                                                                                          disturbance)           damage                                                    in action   abundance
                                                                                                                                                                             area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
California sea lion........................  U.S...........................      113,419         4,789     87           9         0.71   118,305       4,085     257,606       2,896          46
Guadalupe fur seal.........................  Mexico........................        1,442            15      0           0            0     1,457       1,171      34,187         124           4

[[Page 5013]]

 
Northern fur seal..........................  California....................       15,167           124      1           0            0    15,292         886      14,050       1,726         109
Harbor seal................................  California....................        2,450         2,994      8           0            0     5,452         321      30,968       1,698          18
Northern elephant seal.....................  California....................       42,916        17,955     97           2            0    60,970       4,108     187,386       1,484          33
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: For the SOCAL take estimates, because of the manner in which the Navy action area overlaps the ranges of many MMPA stocks (i.e., a stock may range far north to Washington state and
  beyond and abundance may only be predicted within the U.S. EEZ, while the Navy action area is limited to Southern California and northern Mexico, but extends beyond the U.S. EEZ), we compare
  predicted takes to both the abundance estimates for the action area, as well as the SARs.
For mortality takes there is an annual average of 0.71 California sea lions (i.e., where five takes could potentially occur divided by 7 years to get the annual number of mortalities/serious
  injuries).

    Below we compile and summarize the information that supports our 
determination that the Navy's activities would not adversely affect any 
pinnipeds through effects on annual rates of recruitment or survival 
for any of the affected species or stocks addressed in this section.
    Five M/SI takes of California sea lions are authorized and when 
this mortality is combined with the other human-caused mortality from 
other sources, it still falls well below the insignificance threshold 
for residual PBR (13,684). A small number of Level A harassment takes 
by tissue damage are also authorized (nine and two for California sea 
lions and northern elephant seals, respectively), which, as discussed 
in the 2020 HSTT final rule, could range in impact from minor to 
something just less than M/SI that could seriously impact fitness. 
However, given the Navy's mitigation, exposure at the closer to the 
source and more severe end of the spectrum is less likely. 
Nevertheless, we cautiously assume some moderate impact on the 
individuals that experience these small numbers of take that could 
lower the individual's fitness within the year such that a female 
(assuming a 50 percent chance of it being a female) might forego 
reproduction for 1 year. As noted previously, foregone reproduction has 
less of an impact on population rates than death (especially for only 
one within 7 years, which is the maximum predicted because the small 
number anticipated in any 1 year makes the probability that any 
individual would be impacted in this way twice in 7 years very low) and 
these low numbers of instances (especially assuming the likelihood that 
only 50 percent of the takes would affect females) are not expected to 
impact annual rates of recruitment or survival, especially given the 
population sizes of these species.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disturbance), for Hawaiian monk seals and Guadalupe fur 
seals, the two species listed under the ESA, the estimated instances of 
takes as compared to the stock abundance does not exceed 124 percent, 
which suggests that some portion of these two stocks would be taken on 
1 to a few days per year. For the remaining stocks, the number of 
estimated total instances of take compared to the abundance (measured 
against both the Navy-estimated abundance and the SAR) is 1,484 to 
2,896 percent and 18 to 46 percent, respectively (table 22). Given the 
ranges of these stocks (i.e., very large ranges, but with individuals 
often staying in the vicinity of haulouts), this information suggests 
that some very small portion of the individuals of these stocks will be 
taken, but that some subset of individuals within the stock will be 
taken repeatedly within the year (perhaps up to 58 days)--potentially 
over a fair number of sequential days. Regarding the severity of those 
individual Level B harassment takes by behavioral disturbance, the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB, which is considered a relatively low to occasionally moderate 
level for pinnipeds. However, as noted, some of these takes could occur 
on a fair number of sequential days for this stock.
    As described in the 2018 HSTT final rule and 2020 HSTT final rule, 
the Hawaii and 4-Islands mitigation areas protect (by not using 
explosives and limiting MFAS within) a significant portion of the 
designated critical habitat for Hawaiian monk seals in the Main 
Hawaiian Islands, including all of it around the islands of Hawaii and 
Lanai, most around Maui, and good portions around Molokai and 
Kaho'olawe. As discussed, this protection reduces the overall number of 
takes and further reduces the severity of effects by minimizing impacts 
near pupping beaches and in important foraging habitat.
    The severity of TTS takes are expected to be low-level, of short 
duration, and mostly not in a frequency band that would be expected to 
interfere significantly with conspecific communication, echolocation, 
or other important low-frequency cues that would affect the 
individual's reproduction or survival. For these same reasons (low 
level and frequency band), while a small permanent loss of hearing 
sensitivity may include some degree of energetic costs for compensating 
or may mean some small loss of opportunities or detection capabilities, 
the one to eight estimated Level A harassment takes by PTS for monk 
seals, northern fur seals, and harbor seals are unlikely to impact 
behaviors, opportunities, or detection capabilities to a degree that 
would interfere with reproductive success or survival of any 
individuals. Because of the high number of PTS takes for California sea 
lions and northern elephant seals (87 and 97, respectively), we 
acknowledge that a few animals could potentially incur permanent 
hearing loss of a higher degree that could potentially interfere with 
their successful reproduction and growth. Given the status of the 
stocks, even if this occurred, it would not adversely impact rates of 
recruitment or

[[Page 5014]]

survival (residual PBR of 13,684 and 5,108, respectively).
    Altogether, an individual Hawaiian monk seal and Guadalupe fur seal 
would be taken no more than a few days in any year with none of the 
expected take anticipated to affect individual reproduction or 
survival, let alone annual rates of recruitment and survival. With all 
other stocks, only a very small portion of the stock will be taken in 
any manner. Of those taken, some individuals will be taken by Level B 
harassment (at a moderate or sometimes low level) over several days a 
year, and some smaller portion of those taken will be on a relatively 
moderate to high number of days across the year (up to 58), a fair 
number of which will likely be sequential days. Though the majority of 
impacts are expected to be of a lower to sometimes moderate severity, 
the repeated takes over a potentially fair number of sequential days 
for some individuals makes it more likely that some number of 
individuals could be interrupted during foraging in a manner and amount 
such that impacts to the energy budgets of females (from either losing 
feeding opportunities or expending considerable energy to find 
alternative feeding options) could cause them to forego reproduction 
for a year (energetic impacts to males are generally meaningless to 
population rates unless they cause death, and it takes extreme energy 
deficits beyond what would ever be likely to result from these 
activities to cause the death of an adult marine mammal). As noted 
previously, however, foregone reproduction (especially for only 1 year 
within 7, which is the maximum predicted because the small number 
anticipated in any 1 year makes the probability that any individual 
would be impacted in this way twice in 7 years very low) has far less 
of an impact on population rates than mortality and a relatively small 
number of instances of foregone reproduction (as compared to the stock 
abundance and residual PBR) are not expected to adversely affect the 
stock through effects on annual rates of recruitment or survival, 
especially given the status of these stocks. Accordingly, we do not 
anticipate the relatively small number of individual northern fur seals 
or harbor seals that might be taken over repeated days within the year 
in a manner that results in 1 year of foregone reproduction to 
adversely affect the stocks through effects on rates of recruitment or 
survival, given the status of the stocks, which are respectively 
increasing and stable with abundances and residual PBRs of 14,050/
30,968 and 449/1,598.
    For California sea lions, given the very high abundance and 
residual PBR (257,606 and 13,684, respectively), as well as the 
increasing status of the stock in the presence of similar levels of 
Navy activities over past years--the impacts of 0.71 annual 
mortalities, potential foregone reproduction for up to nine individuals 
in a year taken by tissue damage, and some relatively small number of 
individuals taken as a result of repeated behavioral harassment over a 
fair number of sequential days are not expected to adversely affect the 
stock through effects on annual rates of recruitment or survival. 
Similarly, for northern elephant seals, given the very high abundance 
and residual PBR (187,386 and 5,108, respectively), as well as the 
increasing status of the stock in the presence of similar levels of 
Navy activities over past years, the impacts of potential foregone 
reproduction for up to 2 individuals in a year taken by tissue damage 
and some relatively small number of individuals taken as a result of 
repeated behavioral harassment over a fair number of sequential days 
are not expected to adversely affect the stock through effects on 
annual rates of recruitment or survival. For these reasons, in 
consideration of all of the effects of the Navy's activities combined 
(M/SI, Level A harassment, and Level B harassment), we have determined 
that the authorized take will have a negligible impact on all pinniped 
species and stocks.

Determination

    The 2018 HSTT final rule included a detailed discussion of all of 
the anticipated impacts on the affected species and stocks from serious 
injury or mortality, Level A harassment, and Level B harassment; 
impacts on habitat; and how the Navy's mitigation and monitoring 
measures reduce the number and/or severity of adverse effects. We have 
evaluated how these impacts as well as additional take of two large 
whales by serious injury or mortality by vessel strike, and the 
required mitigation measures are expected to combine, annually, to 
affect individuals of each species and stock. Those effects were then 
evaluated in the context of whether they are reasonably likely to 
impact reproductive success or survivorship of individuals and then, if 
so, further analyzed to determine whether there would be effects on 
annual rates of recruitment or survival that would adversely affect the 
species or stock.
    As described above, the basis for the negligible impact 
determination is the assessment of effects on annual rates of 
recruitment and survival. Accordingly, the analysis included in the 
2018 HSTT final rule and 2020 HSTT final rule used annual activity 
levels, the best available science, and approved methods to predict the 
annual impacts to marine mammals, which were then analyzed in the 
context of whether each species or stock would incur more than a 
negligible impact based on anticipated adverse impacts to annual rates 
of recruitment or survival. As we have described above, none of the 
factors upon which the conclusions in the 2020 HSTT final rule were 
based have changed, with the exception of estimated take by vessel 
strike. Therefore, even though this final rule includes two additional 
takes by vessel strike, little has changed that would change our 2018 
HSTT final rule and subsequent 2020 HSTT final rule analyses, and it is 
appropriate to rely on those analyses, as well as the new information 
and analysis discussed above, for this final rule.
    Based on the applicable information and analysis from the 2018 HSTT 
final rule and 2020 HSTT final rule, as updated with the information 
and analysis contained herein on the potential and likely effects of 
the specified activities on the affected marine mammals and their 
habitat, and taking into consideration the implementation of the 
monitoring and mitigation measures, NMFS finds that the incidental take 
from the specified activities will have a negligible impact on all 
affected marine mammal species and stocks.

Subsistence Harvest of Marine Mammals

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

Classification

Endangered Species Act

    There are nine marine mammal species under NMFS jurisdiction that 
are listed as endangered or threatened under the ESA with confirmed or 
possible occurrence in the HSTT Study Area: blue whale, fin whale, gray 
whale (Western North Pacific DPS), humpback whale (Mexico and Central 
America DPSs), sei whale, sperm whale, false killer whale (Main 
Hawaiian Islands Insular DPS), Hawaiian monk seal, and

[[Page 5015]]

Guadalupe fur seal. There is also ESA-designated critical habitat for 
Hawaiian monk seals and Main Hawaiian Islands Insular false killer 
whales. The Navy consulted with NMFS pursuant to section 7 of the ESA 
for HSTT activities. NMFS also consulted internally on the issuance of 
the 2018 HSTT regulations and LOAs under section 101(a)(5)(A) of the 
MMPA.
    NMFS issued a Biological Opinion on December 10, 2018 concluding 
that the issuance of the 2018 HSTT final rule and subsequent LOAs are 
not likely to jeopardize the continued existence of the threatened and 
endangered species under NMFS' jurisdiction and are not likely to 
result in the destruction or adverse modification of critical habitat 
in the HSTT Study Area. The 2018 Biological Opinion included specified 
conditions under which NMFS would be required to reinitiate section 7 
consultation. NMFS reviewed these specified conditions for the 2020 
HSTT rulemaking and determined that reinitiation of consultation was 
not warranted. The incidental take statement that accompanied the 2018 
Biological Opinion was amended to cover the 7-year period of the 2020 
HSTT rule. The 2018 Biological Opinion for this action is available at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
    The 2018 Biological Opinion reinitiation clause (2), states that 
formal consultation should be reinitiated if ``new information reveals 
effects of the agency action that may affect ESA-listed species or 
critical habitat in a manner or to an extent not previously 
considered.'' Given the new information regarding the recent occurrence 
of large whale strikes by naval vessels in the southern California 
portion of the HSTT Study Area, as described herein, the Navy 
reinitiated consultation with NMFS pursuant to section 7 of the ESA for 
HSTT Study Area activities, and NMFS also reinitiated consultation 
internally on the issuance of these revised regulations and LOAs under 
section 101(a)(5)(A) of the MMPA.
    NMFS issued a reinitiated Biological and Conference Opinion on June 
3, 2024 concluding that the issuance of the 2024 HSTT final rule and 
subsequent LOAs are not likely to jeopardize the continued existence of 
the threatened and endangered species under NMFS' jurisdiction and are 
not likely to result in the destruction or adverse modification of 
critical habitat in the HSTT Study Area. The opinion is available at 
https://doi.org/10.25923/7y9x-vw84.

National Marine Sanctuaries Act

    Federal agency actions that are likely to injure national marine 
sanctuary resources are subject to consultation with the Office of 
National Marine Sanctuaries (ONMS) under section 304(d) of the National 
Marine Sanctuaries Act (NMSA). There are two national marine 
sanctuaries in the HSTT Study Area, the Hawaiian Islands Humpback Whale 
National Marine Sanctuary and the Channel Islands National Marine 
Sanctuary. NMFS has fulfilled its responsibilities and completed all 
requirements under the NMSA.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must evaluate our proposed actions and alternatives with respect 
to potential impacts on the human environment. NMFS participated as a 
cooperating agency on the 2018 HSTT FEIS/OEIS (published on October 26, 
2018, http://www.hstteis.com) which evaluated impacts from Navy 
training and testing activities in the HSTT Study Area for the 
reasonably foreseeable future (including through 2025). In accordance 
with 40 CFR 1506.3, NMFS independently reviewed and evaluated the 2018 
HSTT FEIS/OEIS and determined that it was adequate and sufficient to 
meet our responsibilities under NEPA for the issuance of the 2018 HSTT 
final rule and associated LOAs. NMFS therefore adopted the 2018 HSTT 
FEIS/OEIS.
    In accordance with 40 CFR 1502.9 and the information and analysis 
contained in this final rule, NMFS has determined that this final rule 
and any subsequent LOAs will not result in impacts that were not fully 
considered in the 2018 HSTT FEIS/OEIS. As indicated in this final rule, 
the Navy has made no substantial changes to the activities that are 
relevant to environmental concerns nor are there substantial new 
circumstances or information about the significance of adverse effects 
that bear on the analysis. Therefore, NMFS has determined that the 2018 
HSTT FEIS/OEIS remains valid, and there is no need to supplement the 
document for this rulemaking. NOAA therefore, has adopted the 2018 HSTT 
FEIS/OEIS. NMFS has prepared a separate Record of Decision. NMFS' 
Record of Decision for adoption of the 2018 HSTT FEIS/OEIS and issuance 
of this final rule and subsequent LOAs can be found at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.

Regulatory Flexibility Act

    The Office of Management and Budget has determined that this rule 
is not significant for purposes of Executive Order 12866.
    Pursuant to the Regulatory Flexibility Act (RFA), the Chief Counsel 
for Regulation of the Department of Commerce has certified to the Chief 
Counsel for Advocacy of the Small Business Administration during the 
proposed rule stage that this action would not have a significant 
economic impact on a substantial number of small entities. The factual 
basis for the certification was published in the proposed rule and is 
not repeated here. No comments were received regarding this 
certification. As a result, a regulatory flexibility analysis was not 
required and none was prepared.

Waiver of Delay in Effective Date Under the Administrative Procedure 
Act

    NMFS has determined that there is good cause under the 
Administrative Procedure Act (5 U.S.C. 553(d)) to waive the 30-day 
delay of the effective date for this rule. This rule relieves the Navy 
from the restrictions of the take prohibitions under the MMPA by 
granting the Navy's request for incidental take authorization under 
MMPA section 101(a)(5)(A). In addition, there is good cause to waive 
the 30-day effective date period because a delay would be contrary to 
the public interest and unnecessary. A delay in effectiveness is 
contrary to public interest because this rule allows the Navy to 
continue training and testing activities that are necessary for 
national security in compliance with the MMPA. Further, a delay is 
unnecessary because this rule is not generally applicable to the 
public. The Navy is the only entity affected by the regulations, the 
Navy specifically requested the modification to the regulations, and 
the Navy has fully agreed to the requirements included herein. The Navy 
is anticipating finalization of the rule and, as such, is ready to 
comply immediately upon publication. As such, there is good cause to 
waive the 30-day delay in effective date.

List of Subjects in 50 CFR Part 218

    Administrative practice and procedure, Endangered and threatened 
species, Fish, Fisheries, Marine mammals, Penalties, Reporting and 
recordkeeping requirements, Transportation, Wildlife.


[[Page 5016]]


    Dated: December 23, 2024.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.

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

PART 218--REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE 
MAMMALS

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

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

0
2. Revise subpart H to read as follows:
Subpart H--Taking and Importing Marine Mammals; U.S. Navy's Hawaii-
Southern California Training and Testing (HSTT)
Sec.
218.70 Specified activity and geographical region.
218.71 Effective dates.
218.72 Permissible methods of taking.
218.73 Prohibitions.
218.74 Mitigation requirements.
218.75 Requirements for monitoring and reporting.
218.76 Letters of Authorization (LOA).
218.77 Renewals and modifications of Letters of Authorization.
218.78-218.79 [Reserved]

Subpart H--Taking and Importing Marine Mammals; U.S. Navy's Hawaii-
Southern California Training and Testing (HSTT)


Sec.  218.70   Specified activity and geographical region.

    (a) Regulations in this subpart apply only to the U.S. Navy (Navy) 
for the taking of marine mammals that occurs in the area described in 
paragraph (b) of this section and that occurs incidental to the 
activities listed in paragraph (c) of this section.
    (b) The taking of marine mammals by the Navy under this subpart may 
be authorized in Letters of Authorization (LOAs) only if it occurs 
within the Hawaii-Southern California Training and Testing (HSTT) Study 
Area, which includes established operating and warning areas across the 
north-central Pacific Ocean, from the mean high tide line in Southern 
California west to Hawaii and the International Date Line. The HSTT 
Study Area includes the at-sea areas of three existing range complexes, 
the Hawaii Range Complex (HRC), the Southern California Range Complex 
(SOCAL), and the Silver Strand Training Complex, and overlaps a portion 
of the Point Mugu Sea Range (PMSR). Also included in the HSTT Study 
Area are Navy pierside locations in Hawaii and Southern California, 
Pearl Harbor, San Diego Bay, and the transit corridor on the high seas 
where sonar training and testing may occur.
    (c) The taking of marine mammals by the Navy is only authorized if 
it occurs incidental to the Navy conducting training and testing 
activities:
    (1) Training. (i) Amphibious warfare;
    (ii) Anti-submarine warfare;
    (iii) Electronic warfare;
    (iv) Expeditionary warfare;
    (v) Mine warfare;
    (vi) Surface warfare; and
    (vii) Pile driving.
    (2) Testing. (i) Naval Air Systems Command Testing Activities;
    (ii) Naval Sea System Command Testing Activities;
    (iii) Office of Naval Research Testing Activities; and
    (iv) Naval Information Warfare Systems Command.


Sec.  218.71   Effective dates.

    This subpart is effective from January 16, 2025, through December 
20, 2025.


Sec.  218.72  Permissible methods of taking.

    (a) Under LOAs issued pursuant to Sec. Sec.  216.106 of this 
chapter and 218.76, the Holder of the LOAs (hereinafter ``Navy'') may 
incidentally, but not intentionally, take marine mammals within the 
area described in Sec.  218.70(b) by Level A harassment and Level B 
harassment associated with the use of active sonar and other acoustic 
sources and explosives as well as serious injury or mortality 
associated with vessel strikes and explosives, provided the activity is 
in compliance with all terms, conditions, and requirements of these 
regulations in this subpart and the applicable LOAs.
    (b) The incidental take of marine mammals by the activities listed 
in Sec.  218.70(c) is limited to the following species:

                        Table 1 to Paragraph (b)
------------------------------------------------------------------------
                Species                               Stock
------------------------------------------------------------------------
Blue whale.............................  Central North Pacific
Blue whale.............................  Eastern North Pacific
Bryde's whale..........................  Eastern Tropical Pacific
Bryde's whale..........................  Hawaii
Fin whale..............................  CA/OR/WA
Fin whale..............................  Hawaii
Humpback whale.........................  Central America/Southern Mexico-
                                          CA/OR/WA
Humpback whale.........................  Mainland Mexico-CA/OR/WA
Humpback whale.........................  Hawaii
Minke whale............................  CA/OR/WA
Minke whale............................  Hawaii
Sei whale..............................  Eastern North Pacific
Sei whale..............................  Hawaii
Gray whale.............................  Eastern North Pacific
Gray whale.............................  Western North Pacific
Sperm whale............................  CA/OR/WA
Sperm whale............................  Hawaii
Dwarf sperm whale......................  Hawaii
Pygmy sperm whale......................  Hawaii
Kogia whales...........................  CA/OR/WA
Baird's beaked whale...................  CA/OR/WA
Blainville's beaked whale..............  Hawaii
Goose-beaked whale.....................  CA/OR/WA
Goose-beaked whale.....................  Hawaii
Longman's beaked whale.................  Hawaii
Mesoplodon spp.........................  CA/OR/WA

[[Page 5017]]

 
Bottlenose dolphin.....................  California Coastal
Bottlenose dolphin.....................  CA/OR/WA Offshore
Bottlenose dolphin.....................  Hawaii Pelagic
Bottlenose dolphin.....................  Kauai & Niihau
Bottlenose dolphin.....................  Oahu
Bottlenose dolphin.....................  4-Island
Bottlenose dolphin.....................  Hawaii
False killer whale.....................  Hawaii Pelagic
False killer whale.....................  Main Hawaiian Islands Insular
False killer whale.....................  Northwestern Hawaiian Islands
Fraser's dolphin.......................  Hawaii
Killer whale...........................  Eastern North Pacific (ENP)
                                          Offshore
Killer whale...........................  ENP Transient/West Coast
                                          Transient
Killer whale...........................  Hawaii
Long-beaked common dolphin.............  California
Melon-headed whale.....................  Hawaiian Islands
Melon-headed whale.....................  Kohala Resident
Northern right whale dolphin...........  CA/OR/WA
Pacific white-sided dolphin............  CA/OR/WA
Pantropical spotted dolphin............  Hawaii Island
Pantropical spotted dolphin............  Hawaii Pelagic
Pantropical spotted dolphin............  Oahu
Pantropical spotted dolphin............  4-Island
Pygmy killer whale.....................  Hawaii
Pygmy killer whale.....................  Tropical
Risso's dolphin........................  CA/OR/WA
Risso's dolphin........................  Hawaii
Rough-toothed dolphin..................  Hawaii
Short-beaked common dolphin............  CA/OR/WA
Short-finned pilot whale...............  CA/OR/WA
Short-finned pilot whale...............  Hawaii
Spinner dolphin........................  Hawaii Island
Spinner dolphin........................  Hawaii Pelagic
Spinner dolphin........................  Kauai & Niihau
Spinner dolphin........................  Oahu & 4-Island
Striped dolphin........................  CA/OR/WA
Striped dolphin........................  Hawaii
Dall's porpoise........................  CA/OR/WA
California sea lion....................  U.S.
Guadalupe fur seal.....................  Mexico
Northern fur seal......................  California
Harbor seal............................  California
Hawaiian monk seal.....................  Hawaii
Northern elephant seal.................  California
------------------------------------------------------------------------
Note to Table 1: CA/OR/WA = California/Oregon/Washington.

Sec.  218.73   Prohibitions.

    Except for incidental takings contemplated in Sec.  218.72(a) and 
authorized by LOAs issued under Sec. Sec.  216.106 of this chapter and 
218.76, it is unlawful for any person to do any of the following in 
connection with the activities listed in Sec.  218.70(c):
    (a) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or an LOA issued under Sec. Sec.  216.106 
of this chapter and 218.76;
    (b) Take any marine mammal not specified in Sec.  218.72(b);
    (c) Take any marine mammal specified in Sec.  218.72(b) in any 
manner other than as specified in the LOAs; or
    (d) Take a marine mammal specified in Sec.  218.72(b) after NMFS 
determines such taking results in more than a negligible impact on the 
species or stocks of such marine mammal.


Sec.  218.74   Mitigation requirements.

    When conducting the activities identified in Sec.  218.70(c), the 
mitigation measures contained in any LOAs issued under Sec. Sec.  
216.106 of this chapter and 218.76 must be implemented. These 
mitigation measures include, but are not limited to:
    (a) Procedural mitigation. Procedural mitigation is mitigation that 
the Navy must implement whenever and wherever an applicable training or 
testing activity takes place within the HSTT Study Area for each 
applicable activity category or stressor category and includes acoustic 
stressors (i.e., active sonar, air guns, pile driving, weapons firing 
noise), explosive stressors (i.e., sonobuoys, torpedoes, medium-caliber 
and large-caliber projectiles, missiles and rockets, bombs, sinking 
exercises, mines, anti-swimmer grenades, and mat weave and obstacle 
loading), and physical disturbance and strike stressors (i.e., vessel 
movement; towed in-water devices; small-, medium-, and large-caliber 
non-explosive practice munitions; non-explosive missiles and rockets; 
and non-explosive bombs and mine shapes).
    (1) Environmental awareness and education. Navy personnel 
(including civilian personnel) involved in mitigation and training or 
testing activity reporting under the specified activities will complete 
one or more modules identified in their career path training plan, as 
specified in the LOAs.
    (2) Active sonar. Active sonar includes low-frequency active sonar, 
mid-frequency active sonar, and high-frequency active sonar. For 
vessel-based

[[Page 5018]]

activities, mitigation applies only to sources that are positively 
controlled and deployed from manned surface vessels (e.g., sonar 
sources towed from manned surface platforms). For aircraft-based 
activities, mitigation applies only to sources that are positively 
controlled and deployed from manned aircraft that do not operate at 
high altitudes (e.g., rotary-wing aircraft). Mitigation does not apply 
to active sonar sources deployed from unmanned aircraft or aircraft 
operating at high altitudes (e.g., maritime patrol aircraft). For 
active sonar subject mitigation requirements:
    (i) Number of Lookouts and observation platform--(A) Hull-mounted 
sources. One Lookout is required for hull-mounted sources for platforms 
with space or manning restrictions while underway (at the forward part 
of a small boat or ship) and for platforms using active sonar while 
moored or at anchor (including pierside). Two Lookouts are required for 
hull mounted-sources for platforms without space or manning 
restrictions while underway (at the forward part of the ship).
    (B) Sources that are not hull-mounted sources. One Lookout is 
required on the ship or aircraft conducting the activity for sources 
that are not hull-mounted.
    (ii) Mitigation zone and requirements. During active sonar use, the 
following requirements apply:
    (A) Powerdown for marine mammals at 1,000 yards. At 1,000 yards 
(yd) (914.4 m) from a marine mammal, Navy personnel must power down by 
6 decibels (dB).
    (B) Powerdown for marine mammals at 500 yards. At 500 yd (457.2 m) 
from a marine mammal, Navy personnel must power down by an additional 4 
dB (for a total of 10 dB).
    (C) Shutdowns for marine mammals at 200 yards. At 200 yd (182.9 m) 
from a marine mammal, Navy personnel must shut down low-frequency 
active sonar >=200 dB and hull-mounted mid-frequency active sonar; or 
Navy personnel must shut down low-frequency active sonar <200 dB, mid-
frequency active sonar sources that are not hull-mounted, and high-
frequency active sonar.
    (D) Prior to activity. Prior to the start of the active sonar 
activity (e.g., when maneuvering on station), Navy personnel must 
observe the 1,000 yd (914.4 m) mitigation zone for floating vegetation; 
if floating vegetation is observed in the mitigation zone, Navy 
personnel must relocate or delay the start of active sonar transmission 
until the mitigation zone is clear. Navy personnel must also observe 
the mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must relocate or delay the start of active sonar 
transmission.
    (E) During the activity for low-frequency active sonar at or above 
200 dB and hull-mounted mid-frequency active sonar. When using low-
frequency active sonar at or above 200 dB and hull-mounted mid-
frequency active sonar, Navy personnel must observe the 1,000 yd (914.4 
m) mitigation zone for marine mammals and power down active sonar 
transmission by 6 dB if marine mammals are observed within 1,000 yd 
(914.4 m) of the sonar source; power down by an additional 4 dB (for a 
total of 10 dB total) if marine mammals are observed within 500 yd 
(457.2 m) of the sonar source; and cease transmission if marine mammals 
are observed within 200 yd (182.9 m) of the sonar source.
    (F) During the activity for low-frequency active sonar below 200 
dB, mid-frequency active sonar sources that are not hull mounted, and 
high-frequency active sonar. During the activity for low-frequency 
active sonar below 200 dB, mid-frequency active sonar sources that are 
not hull mounted, and high-frequency active sonar, Navy personnel must 
observe the 1,000 yd (914.4 m) mitigation zone for marine mammals and 
cease active sonar transmission if marine mammals are observed within 
200 yd (182.9 m) of the sonar source.
    (G) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone indicated in Sec.  
218.74(a)(2)(ii) prior to the initial start of the activity (by 
delaying the start) or during the activity (by not recommencing or 
powering up active sonar transmission) until one of the following 
conditions has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the sonar source;
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 minutes (min) for aircraft-
deployed sonar sources or 30 min for vessel-deployed sonar sources;
    (4) Sonar source transit. For mobile activities, the active sonar 
source has transited a distance equal to double that of the mitigation 
zone size beyond the location of the last sighting; or
    (5) Bow-riding dolphins. For activities using hull-mounted sonar 
where a dolphin(s) is observed in the mitigation zone, the Lookout 
concludes that the dolphin(s) are deliberately closing in on the ship 
to ride the ship's bow wave, and are therefore out of the main 
transmission axis of the sonar (and there are no other marine mammal 
sightings within the mitigation zone).
    (3) Air guns. For activities using air guns:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on a ship or pierside.
    (ii) Mitigation zone and requirements. The mitigation zone is 150 
yd (137.2 m) around the air gun.
    (A) Prior to activity. Prior to the initial start of the activity 
(e.g., when maneuvering on station), Navy personnel must observe the 
mitigation zone for floating vegetation; if floating vegetation is 
observed, Navy personnel must relocate or delay the start until the 
mitigation zone is clear. Navy personnel must also observe the 
mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must relocate or delay the start of air gun use.
    (B) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must cease air gun use.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing air gun use) until one of the following conditions 
has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the air gun;
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 30 min; or
    (4) Air gun transit. For mobile activities, the air gun has 
transited a distance equal to double that of the mitigation zone size 
beyond the location of the last sighting.
    (4) Pile driving. For pile driving and pile extraction sound during 
Elevated Causeway System training:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on the shore, the elevated causeway, or a small boat.
    (ii) Mitigation zone and requirements. The mitigation zone is 100 
yd (91.4 m) around the pile driver.

[[Page 5019]]

    (A) Prior to activity. Prior to the initial start of the activity 
(for 30 min), Navy personnel must observe the mitigation zone for 
floating vegetation; if floating vegetation is observed, Navy personnel 
must delay the start until the mitigation zone is clear. Navy personnel 
also must observe the mitigation zone for marine mammals; if marine 
mammals are observed, Navy personnel must delay the start of pile 
driving or vibratory pile extraction.
    (B) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must cease impact pile driving or vibratory 
pile extraction.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing pile driving or pile extraction) until one of the 
following conditions has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the pile driving location; or
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 30 minutes.
    (5) Weapons firing noise. For weapons firing noise associated with 
large-caliber gunnery activities:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on the ship conducting the firing. Depending on the 
activity, the Lookout could be the same as the one provided for under 
``Explosive medium-caliber and large-caliber projectiles'' or under 
``Small-, medium-, and large-caliber non-explosive practice munitions'' 
in paragraphs (a)(8)(i) and (a)(18)(i) of this section.
    (ii) Mitigation zone and requirements. The mitigation zone is 30 
degrees on either side of the firing line out to 70 yd (64 m) from the 
muzzle of the weapon being fired.
    (A) Prior to activity. Prior to the start of the activity, Navy 
personnel must observe the mitigation zone for floating vegetation; if 
floating vegetation is observed, Navy personnel must relocate or delay 
the start of weapons firing until the mitigation zone is clear. Navy 
personnel must also observe the mitigation zone for marine mammals; if 
marine mammals are observed, Navy personnel must relocate or delay the 
start of weapons firing.
    (B) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must cease weapons firing.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing weapons firing) until one of the following 
conditions has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the firing ship;
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 30 min; or
    (4) Firing ship transit. For mobile activities, the firing ship has 
transited a distance equal to double that of the mitigation zone size 
beyond the location of the last sighting.
    (6) Explosive sonobuoys. For explosive sonobuoys:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned in an aircraft or on a small boat. If additional 
platforms are participating in the activity, Navy personnel positioned 
in those assets (e.g., safety observers, evaluators) must support 
observing the mitigation zone while performing their regular duties.
    (ii) Mitigation zone and requirements. The mitigation zone is 600 
yd (548.6 m) around an explosive sonobuoy.
    (A) Prior to activity. Prior to the initial start of the activity 
(e.g., during deployment of a sonobuoy field, which typically lasts 20-
30 min), Navy personnel must observe the mitigation zone for floating 
vegetation; if floating vegetation is observed, Navy personnel must 
relocate or delay the start of sonobuoy or source/receiver pair 
detonations until the mitigation zone is clear. Navy personnel must 
conduct passive acoustic monitoring for marine mammals and use 
information from detections to assist visual observations. Navy 
personnel also must visually observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must relocate 
or delay the start of sonobuoy or source/receiver pair detonations.
    (B) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must cease sonobuoy or source/receiver pair 
detonations.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing detonations) until one of the following conditions 
has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the sonobuoy; or
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min when the activity 
involves aircraft that have fuel constraints (e.g., helicopter), or 30 
min when the activity involves aircraft that are not typically fuel 
constrained.
    (D) After activity. After completion of the activity (e.g., prior 
to maneuvering off station), when practical (e.g., when platforms are 
not constrained by fuel restrictions or mission-essential follow-on 
commitments), Navy personnel must observe for marine mammals in the 
vicinity of where detonations occurred; if any injured or dead marine 
mammals are observed, Navy personnel must follow established incident 
reporting procedures. If additional platforms are supporting this 
activity (e.g., providing range clearance), these Navy assets must 
assist in the visual observation of the area where detonations 
occurred.
    (7) Explosive torpedoes. For explosive torpedoes:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned in an aircraft. If additional platforms are participating 
in the activity, Navy personnel positioned in those assets (e.g., 
safety observers, evaluators) must support observing the mitigation 
zone while performing their regular duties.
    (ii) Mitigation zone and requirements. The mitigation zone is 2,100 
yd (1,920.2 m) around the intended impact location.
    (A) Prior to activity. Prior to the initial start of the activity 
(e.g., during deployment of the target), Navy personnel must observe 
the mitigation zone for floating vegetation and jellyfish aggregations; 
if floating vegetation or jellyfish aggregations are observed, Navy 
personnel must relocate or delay the start of firing until the 
mitigation zone

[[Page 5020]]

is clear. Navy personnel must conduct passive acoustic monitoring for 
marine mammals and use the information from detections to assist visual 
observations. Navy personnel also must visually observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must relocate or delay the start of firing.
    (B) During activity. During the activity, Navy personnel must 
observe for marine mammals and jellyfish aggregations; if marine 
mammals or jellyfish aggregations are observed, Navy personnel must 
cease firing.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the intended impact location; or
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min when the activity 
involves aircraft that have fuel constraints, or 30 min when the 
activity involves aircraft that are not typically fuel constrained.
    (D) After activity. After completion of the activity (e.g., prior 
to maneuvering off station), Navy personnel must when practical (e.g., 
when platforms are not constrained by fuel restrictions or mission-
essential follow-on commitments), observe for marine mammals in the 
vicinity of where detonations occurred; if any injured or dead marine 
mammals are observed, Navy personnel must follow established incident 
reporting procedures. If additional platforms are supporting this 
activity (e.g., providing range clearance), these Navy assets must 
assist in the visual observation of the area where detonations 
occurred.
    (8) Explosive medium-caliber and large-caliber projectiles. For 
gunnery activities using explosive medium-caliber and large-caliber 
projectiles, the following mitigation applies to activities using a 
surface target:
    (i) Number of Lookouts and observation platform. One Lookout must 
be on the vessel or aircraft conducting the activity. For activities 
using explosive large-caliber projectiles, depending on the activity, 
the Lookout could be the same as the one described in ``Weapons firing 
noise'' in paragraph (a)(5)(i) of this section. If additional platforms 
are participating in the activity, Navy personnel positioned in those 
assets (e.g., safety observers, evaluators) must support observing the 
mitigation zone while performing their regular duties.
    (ii) Mitigation zone and requirements--(A) Air-to-surface 
activities. The mitigation zone is 200 yd (182.9 m) around the intended 
impact location for air-to-surface activities using explosive medium-
caliber projectiles.
    (B) Surface-to-surface activities, medium-caliber. The mitigation 
zone is 600 yd (548.6 m) around the intended impact location for 
surface-to-surface activities using explosive medium-caliber 
projectiles.
    (C) Surface-to-surface activities, large-caliber. The mitigation 
zone is 1,000 yd (914.4 m) around the intended impact location for 
surface-to-surface activities using explosive large-caliber 
projectiles.
    (D) Prior to activity. Prior to the start of the activity (e.g., 
when maneuvering on station), Navy personnel must observe the 
mitigation zone for floating vegetation; if floating vegetation is 
observed, Navy personnel must relocate or delay the start of firing 
until the mitigation zone is clear. Navy personnel also must observe 
the mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must relocate or delay the start of firing.
    (E) During activity. During the activity, Navy personnel must 
observe for marine mammals; if marine mammals are observed, Navy 
personnel must cease firing.
    (F) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the intended impact location;
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min for aircraft-based 
firing or 30 min for vessel-based firing; or for activities using 
mobile targets, the intended impact location has transited a distance 
equal to double that of the mitigation zone size beyond the location of 
the last sighting.
    (G) After activity. After completion of the activity (e.g., prior 
to maneuvering off station), Navy personnel must, when practical (e.g., 
when platforms are not constrained by fuel restrictions or mission-
essential follow-on commitments), observe for marine mammals in the 
vicinity of where detonations occurred; if any injured or dead marine 
mammals are observed, Navy personnel must follow established incident 
reporting procedures. If additional platforms are supporting this 
activity (e.g., providing range clearance), these Navy assets must 
assist in the visual observation of the area where detonations 
occurred.
    (9) Explosive missiles and rockets. For aircraft-deployed explosive 
missiles and rockets. Mitigation applies to activities using a surface 
target:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned in an aircraft. If additional platforms are participating 
in the activity, Navy personnel positioned in those assets (e.g., 
safety observers, evaluators) must support observing the mitigation 
zone while performing their regular duties.
    (ii) Mitigation zone and requirements--(A) Missiles or rockets with 
0.6-20 lb net explosive weight. The mitigation zone is 900 yd (823 m) 
around the intended impact location for missiles or rockets with 0.6-20 
lb net explosive weight.
    (B) Missiles with 21-500 lb net explosive weight. The mitigation 
zone is 2,000 yd (1,828.8 m) around the intended impact location for 
missiles with 21-500 lb net explosive weight.
    (C) Prior to activity. Prior to the initial start of the activity 
(e.g., during a fly-over of the mitigation zone), Navy personnel must 
observe the mitigation zone for floating vegetation; if floating 
vegetation is observed, Navy personnel must relocate or delay the start 
of firing until the mitigation zone is clear. Navy personnel also must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must relocate or delay the start of firing.
    (D) During activity. During the activity, Navy personnel must 
observe for marine mammals; if marine mammals are observed, Navy 
personnel must cease firing.
    (E) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the

[[Page 5021]]

activity (by delaying the start) or during the activity (by not 
recommencing firing) until one of the following conditions has been 
met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the intended impact location; or
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min when the activity 
involves aircraft that have fuel constraints, or 30 min when the 
activity involves aircraft that are not typically fuel constrained.
    (F) After activity. After completion of the activity (e.g., prior 
to maneuvering off station), Navy personnel must, when practical (e.g., 
when platforms are not constrained by fuel restrictions or mission-
essential follow-on commitments), observe for marine mammals in the 
vicinity of where detonations occurred; if any injured or dead marine 
mammals are observed, Navy personnel must follow established incident 
reporting procedures. If additional platforms are supporting this 
activity (e.g., providing range clearance), these Navy assets will 
assist in the visual observation of the area where detonations 
occurred.
    (10) Explosive bombs. For explosive bombs:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned in an aircraft conducting the activity. If additional 
platforms are participating in the activity, Navy personnel positioned 
in those assets (e.g., safety observers, evaluators) must support 
observing the mitigation zone while performing their regular duties.
    (ii) Mitigation zone and requirements. The mitigation zone is 2,500 
yd (2,286 m) around the intended target.
    (A) Prior to activity. Prior to the initial start of the activity 
(e.g., when arriving on station), Navy personnel must observe the 
mitigation zone for floating vegetation; if floating vegetation is 
observed, Navy personnel must relocate or delay the start of bomb 
deployment until the mitigation zone is clear. Navy personnel also must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must relocate or delay the start of bomb 
deployment.
    (B) During activity. During the activity (e.g., during target 
approach), Navy personnel must observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must cease bomb 
deployment.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing bomb deployment) until one of the following 
conditions has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the intended target;
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min; or for activities using 
mobile targets, the intended target has transited a distance equal to 
double that of the mitigation zone size beyond the location of the last 
sighting.
    (D) After activity. After completion of the activity (e.g., prior 
to maneuvering off station), Navy personnel must, when practical (e.g., 
when platforms are not constrained by fuel restrictions or mission-
essential follow-on commitments), observe for marine mammals in the 
vicinity of where detonations occurred; if any injured or dead marine 
mammals are observed, Navy personnel must follow established incident 
reporting procedures. If additional platforms are supporting this 
activity (e.g., providing range clearance), these Navy assets must 
assist in the visual observation of the area where detonations 
occurred.
    (11) Sinking exercises. For sinking exercises:
    (i) Number of Lookouts and observation platform. Two Lookouts (one 
must be positioned in an aircraft and one must be positioned on a 
vessel). If additional platforms are participating in the activity, 
Navy personnel positioned in those assets (e.g., safety observers, 
evaluators) must support observing the mitigation zone while performing 
their regular duties.
    (ii) Mitigation zone and requirements. The mitigation zone is 2.5 
nautical miles (4.6 km) around the target ship hulk.
    (A) Prior to activity. Prior to the initial start of the activity 
(90 min prior to the first firing), Navy personnel must conduct aerial 
observations of the mitigation zone for floating vegetation and 
jellyfish aggregations; if floating vegetation or jellyfish 
aggregations are observed, Navy personnel must delay the start of 
firing until the mitigation zone is clear. Navy personnel also must 
conduct aerial observations of the mitigation zone for marine mammals; 
if marine mammals are observed, Navy personnel must delay the start of 
firing.
    (B) During activity. During the activity, Navy personnel must 
conduct passive acoustic monitoring for marine mammals and use the 
information from detections to assist visual observations. Navy 
personnel must visually observe the mitigation zone for marine mammals 
from the vessel; if marine mammals are observed, Navy personnel must 
cease firing. Immediately after any planned or unplanned breaks in 
weapons firing of longer than 2 hours, Navy personnel must observe the 
mitigation zone for marine mammals from the aircraft and vessel; if 
marine mammals are observed, Navy personnel must delay recommencement 
of firing.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the target ship hulk; or
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 30 minutes.
    (D) After activity. After completion of the activity (for 2 hours 
after sinking the vessel or until sunset, whichever comes first), Navy 
personnel must observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets will assist in the visual 
observation of the area where detonations occurred.
    (12) Explosive mine countermeasure and neutralization activities. 
For explosive mine countermeasure and neutralization activities:
    (i) Number of Lookouts and observation platform--(A) Smaller 
mitigation zone. One Lookout must be positioned on a vessel or in an 
aircraft when implementing the smaller mitigation zone.
    (B) Larger mitigation zone. Two Lookouts (one must be positioned in 
an aircraft and one must be on a small boat)

[[Page 5022]]

when implementing the larger mitigation zone.
    (C) Additional platforms. If additional platforms are participating 
in the activity, Navy personnel positioned in those assets (e.g., 
safety observers, evaluators) must support observing the mitigation 
zone while performing their regular duties.
    (ii) Mitigation zone and requirements--(A) Activities using 0.1-5 
lb net explosive weight. The mitigation zone is 600 yd (548.6 m) around 
the detonation site for activities using 0.1-5 lb net explosive weight.
    (B) Activities using 6-650 lb net explosive weight. The mitigation 
zone is 2,100 yd (1,920.2 m) around the detonation site for activities 
using 6-650 lb net explosive weight (including high explosive target 
mines).
    (C) Prior to activity. Prior to the initial start of the activity 
(e.g., when maneuvering on station; typically, 10 min when the activity 
involves aircraft that have fuel constraints, or 30 min when the 
activity involves aircraft that are not typically fuel constrained), 
Navy personnel must observe the mitigation zone for floating 
vegetation; if floating vegetation is observed, Navy personnel must 
relocate or delay the start of detonations until the mitigation zone is 
clear. Navy personnel also must observe the mitigation zone for marine 
mammals; if marine mammals are observed, Navy personnel must relocate 
or delay the start of detonations.
    (D) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals, concentrations of 
seabirds, and individual foraging seabirds; if marine mammals, 
concentrations of seabirds, or individual foraging seabirds are 
observed, Navy personnel must cease detonations.
    (E) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity or a sighting of seabird 
concentrations or individual foraging seabirds during the activity. 
Navy personnel must allow a sighted animal to leave the mitigation zone 
prior to the initial start of the activity (by delaying the start) or 
during the activity (by not recommencing detonations) until one of the 
following conditions has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to detonation site; or
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min when the activity 
involves aircraft that have fuel constraints, or 30 min when the 
activity involves aircraft that are not typically fuel constrained.
    (F) After activity. After completion of the activity (typically 10 
min when the activity involves aircraft that have fuel constraints, or 
30 min when the activity involves aircraft that are not typically fuel 
constrained), Navy personnel must observe for marine mammals in the 
vicinity of where detonations occurred; if any injured or dead marine 
mammals are observed, Navy personnel must follow established incident 
reporting procedures. If additional platforms are supporting this 
activity (e.g., providing range clearance), these Navy assets must 
assist in the visual observation of the area where detonations 
occurred.
    (13) Explosive mine neutralization activities involving Navy 
divers. For explosive mine neutralization activities involving Navy 
divers:
    (i) Number of Lookouts and observation platform--(A) Smaller 
mitigation zone. Two Lookouts (two small boats with one Lookout each, 
or one Lookout must be on a small boat and one must be in a rotary-wing 
aircraft) when implementing the smaller mitigation zone.
    (B) Larger mitigation zone. Four Lookouts (two small boats with two 
Lookouts each), and a pilot or member of an aircrew must serve as an 
additional Lookout if aircraft are used during the activity, when 
implementing the larger mitigation zone.
    (C) Divers. All divers placing the charges on mines will support 
the Lookouts while performing their regular duties and will report 
applicable sightings to their supporting small boat or Range Safety 
Officer.
    (D) Additional platforms. If additional platforms are participating 
in the activity, Navy personnel positioned in those assets (e.g., 
safety observers, evaluators) must support observing the mitigation 
zone while performing their regular duties.
    (ii) Mitigation zone and requirements--(A) Activities under 
positive control using 0.1-20 lb net explosive weight. The mitigation 
zone is 500 yd (457.2 m) around the detonation site during activities 
under positive control using 0.1-20 lb net explosive weight.
    (B) Activities under positive control using 21-60 lb net explosive 
weight charges. The mitigation zone is 1,000 yd (914.4 m) around the 
detonation site during all activities using time-delay fuses (0.1-29 lb 
net explosive weight) and during activities under positive control 
using 21-60 lb net explosive weight charges.
    (C) Prior to activity. Prior to the initial start of the activity 
(e.g., when maneuvering on station for activities under positive 
control; 30 min for activities using time-delay firing devices), Navy 
personnel must observe the mitigation zone for floating vegetation; if 
floating vegetation is observed, Navy personnel must relocate or delay 
the start of detonations or fuse initiation until the mitigation zone 
is clear. Navy personnel also must observe the mitigation zone for 
marine mammals; if marine mammals are observed, Navy personnel must 
relocate or delay the start of detonations or fuse initiation.
    (D) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals, concentrations of 
seabirds, and individual foraging seabirds (in the water and not on 
shore); if marine mammals, concentrations of seabirds, or individual 
foraging seabirds are observed, Navy personnel must cease detonations 
or fuse initiation. To the maximum extent practicable depending on 
mission requirements, safety, and environmental conditions, Navy 
personnel must position boats near the mid-point of the mitigation zone 
radius (but outside of the detonation plume and human safety zone), 
must position themselves on opposite sides of the detonation location 
(when two boats are used), and must travel in a circular pattern around 
the detonation location with one Lookout observing inward toward the 
detonation site and the other observing outward toward the perimeter of 
the mitigation zone. If used, Navy aircraft must travel in a circular 
pattern around the detonation location to the maximum extent 
practicable. Navy personnel must not set time-delay firing devices 
(0.1-29 lb net explosive weight) to exceed 10 minutes.
    (E) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity or a sighting of seabird 
concentrations or individual foraging seabirds during the activity. 
Navy personnel must allow a sighted animal to leave the mitigation zone 
prior to the initial start of the activity (by delaying the start) or 
during the activity (by not recommencing detonations) until one of the 
following conditions has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the detonation site; or

[[Page 5023]]

    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min during activities under 
positive control with aircraft that have fuel constraints, or 30 min 
during activities under positive control with aircraft that are not 
typically fuel constrained and during activities using time-delay 
firing devices.
    (F) After activity. After completion of an activity (for 30 min), 
the Navy must observe for marine mammals for 30 minutes. Navy personnel 
must observe for marine mammals in the vicinity of where detonations 
occurred; if any injured or dead marine mammals are observed, Navy 
personnel must follow established incident reporting procedures. If 
additional platforms are supporting this activity (e.g., providing 
range clearance), these Navy assets must assist in the visual 
observation of the area where detonations occurred.
    (14) Maritime security operations--anti-swimmer grenades--(i) 
Number of Lookouts and observation platform. One Lookout must be 
positioned on the small boat conducting the activity. If additional 
platforms are participating in the activity, Navy personnel positioned 
in those assets (e.g., safety observers, evaluators) must support 
observing the mitigation zone while performing their regular duties.
    (ii) Mitigation zone and requirements. 200 yd (182.9 m) around the 
intended detonation location.
    (A) Prior to activity. Prior to the initial start of the activity 
(e.g., when maneuvering on station), Navy personnel must observe the 
mitigation zone for floating vegetation; if floating vegetation is 
observed, Navy personnel must relocate or delay the start of 
detonations until the mitigation zone is clear. Navy personnel also 
must observe the mitigation zone for marine mammals; if marine mammals 
are observed, Navy personnel must relocate or delay the start of 
detonations.
    (B) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must cease detonations.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing detonations) until one of the following conditions 
has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the intended detonation location;
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 30 min; or
    (4) Detonation location transit. The intended detonation location 
has transited a distance equal to double that of the mitigation zone 
size beyond the location of the last sighting.
    (D) After activity. After completion of the activity (e.g., prior 
to maneuvering off station), Navy personnel must, when practical (e.g., 
when platforms are not constrained by fuel restrictions or mission-
essential follow-on commitments), observe for marine mammals in the 
vicinity of where detonations occurred; if any injured or dead marine 
mammals are observed, Navy personnel must follow established incident 
reporting procedures. If additional platforms are supporting this 
activity (e.g., providing range clearance), these Navy assets will 
assist in the visual observation of the area where detonations 
occurred.
    (15) Underwater demolition multiple charge--mat weave and obstacle 
loading exercises. For underwater demolition multiple charge--mat weave 
and obstacle loading exercises:
    (i) Number of Lookouts and observation platform. Two Lookouts (one 
must be positioned on a small boat and one must be positioned on shore 
from an elevated platform). If additional platforms are participating 
in the activity, Navy personnel positioned in those assets (e.g., 
safety observers, evaluators) must support observing the mitigation 
zone while performing their regular duties.
    (ii) Mitigation zone and requirements. The mitigation zone is 700 
yd (640.1 m) around the intended detonation location.
    (A) Prior to activity. Prior to the initial start of the activity, 
or 30 min prior to the first detonation, the Lookout positioned on a 
small boat must observe the mitigation zone for floating vegetation and 
marine mammals; if floating vegetation or marine mammals are observed, 
Navy personnel must delay the start of detonations until the mitigation 
zone is clear. For 10 min prior to the first detonation, the Lookout 
positioned on shore must use binoculars to observe the mitigation zone 
for marine mammals; if marine mammals are observed, Navy personnel must 
delay the start of detonations.
    (B) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must cease detonations.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing detonations) until one of the following conditions 
has been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the detonation location; or
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min (as determined by the 
Navy shore observer).
    (D) After activity. After completion of the activity (for 30 min), 
the Lookout positioned on a small boat must observe for marine mammals 
in the vicinity of where detonations occurred; if any injured or dead 
marine mammals are observed, Navy personnel must follow established 
incident reporting procedures. If additional platforms are supporting 
this activity (e.g., providing range clearance), these Navy assets must 
assist in the visual observation of the area where detonations 
occurred.
    (16) Vessel movement. The following requirements apply to vessel 
movement, except mitigation will not be applied if: the vessel's safety 
is threatened; the vessel is restricted in its ability to maneuver 
(e.g., during launching and recovery of aircraft or landing craft, 
during towing activities, when mooring); the vessel is operated 
autonomously; or when impracticable based on mission requirements 
(e.g., during Amphibious Assault--Battalion Landing exercise).
    (i) Number of Lookouts and observation platform. One Lookout must 
be on the vessel that is underway.
    (ii) Mitigation zone and requirements--(A) Whales. The mitigation 
zone is 500 yd (457.2 m) around whales.
    (B) Marine mammals other than whales. The mitigation zone is 200 yd 
(182.9 m) around all other marine mammals (except bow-riding dolphins 
and pinnipeds hauled out on man-made navigational structures, port 
structures, and vessels).
    (iii) During the activity. When underway, Navy personnel must 
observe the mitigation zone for marine

[[Page 5024]]

mammals; if marine mammals are observed, Navy personnel must maneuver 
(which may include reducing speed as the mission or circumstances 
allow) to maintain distance.
    (iv) Incident reporting procedures. If a marine mammal vessel 
strike occurs, Navy personnel must follow the established incident 
reporting procedures.
    (v) Post-strike alerts. Navy personnel must send alerts to Navy 
vessels of increased risk of strike following any reported Navy vessel 
strike in the HSTT Study Area.
    (vi) Large whale aggregation alerts. Navy personnel must issue 
real-time notifications to Navy vessels of large whale aggregations 
(four or more whales) within 1 nmi (1.9 km) of a Navy vessel in the 
area between 32-33 degrees North and 117.2-119.5 degrees West.
    (17) Towed in-water devices. The following mitigation applies to 
devices that are towed from a manned surface platform or manned 
aircraft, except the mitigation will not be applied if the safety of 
the towing platform or in-water device is threatened:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on a manned towing platform.
    (ii) Mitigation zone and requirements. The mitigation zone is 250 
yd (228.6 m) around marine mammals.
    (iii) During the activity. During the activity (i.e., when towing 
an in-water device), Navy personnel must observe the mitigation zone 
for marine mammals; if marine mammals are observed, Navy personnel must 
maneuver to maintain distance.
    (18) Small-, medium-, and large-caliber non-explosive practice 
munitions. For small-, medium-, and large-caliber non-explosive 
practice munitions, the following mitigation applies to activities 
using a surface target:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on the platform conducting the activity. Depending on the 
activity, the Lookout could be the same as the one described for 
``Weapons firing noise'' in paragraph (a)(5)(i) of this section.
    (ii) Mitigation zone and requirements. The mitigation zone is 200 
yd (182.9 m) around the intended impact location.
    (A) Prior to activity. Prior to the start of the activity (e.g., 
when maneuvering on station), Navy personnel must observe the 
mitigation zone for floating vegetation; if floating vegetation is 
observed, Navy personnel must relocate or delay the start of firing 
until the mitigation zone is clear. Navy personnel also must observe 
the mitigation zone for marine mammals; if marine mammals are observed, 
Navy personnel must relocate or delay the start of firing.
    (B) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must cease firing.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the intended impact location;
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min for aircraft-based 
firing or 30 min for vessel-based firing; or
    (4) Impact location transit. For activities using a mobile target, 
the intended impact location has transited a distance equal to double 
that of the mitigation zone size beyond the location of the last 
sighting.
    (19) Non-explosive missiles and rockets. For aircraft-deployed non-
explosive missiles and rockets, the following mitigation applies to 
activities using a surface target.
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned in an aircraft.
    (ii) Mitigation zone and requirements. The mitigation zone is 900 
yd (823 m) around the intended impact location.
    (A) Prior to activity. Prior to the initial start of the activity 
(e.g., during a fly-over of the mitigation zone), Navy personnel must 
observe the mitigation zone for floating vegetation; if floating 
vegetation is observed, Navy personnel must relocate or delay the start 
of firing until the mitigation zone is clear. Navy personnel also must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must relocate or delay the start of firing.
    (B) During activity. During the activity, Navy personnel must 
observe the mitigation zone for marine mammals; if marine mammals are 
observed, Navy personnel must cease firing.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting prior to or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met:
    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the intended impact location; or
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min when the activity 
involves aircraft that have fuel constraints, or 30 min when the 
activity involves aircraft that are not typically fuel constrained.
    (20) Non-explosive bombs and mine shapes. For non-explosive bombs 
and non-explosive mine shapes during mine laying activities:
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned in an aircraft.
    (ii) Mitigation zone and requirements. The mitigation zone is 1,000 
yd (914.4 m) around the intended target.
    (A) Prior to activity. Prior to the initial start of the activity 
(e.g., when arriving on station), Navy personnel must observe the 
mitigation zone for floating vegetation; if floating vegetation is 
observed, Navy personnel must relocate or delay the start of bomb 
deployment or mine laying until the mitigation zone is clear. Navy 
personnel also must observe the mitigation zone for marine mammals; if 
marine mammals are observed, Navy personnel must relocate or delay the 
start of bomb deployment or mine laying.
    (B) During activity. During the activity (e.g., during approach of 
the target or intended minefield location), Navy personnel must observe 
the mitigation zone for marine mammals and, if marine mammals are 
observed, Navy personnel must cease bomb deployment or mine laying.
    (C) Commencement/recommencement conditions after a marine mammal 
sighting prior to or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing bomb deployment or mine laying) until one of the 
following conditions has been met:

[[Page 5025]]

    (1) Observed exiting. The animal is observed exiting the mitigation 
zone;
    (2) Thought to have exited. The animal is thought to have exited 
the mitigation zone based on a determination of its course, speed, and 
movement relative to the intended target or minefield location;
    (3) Clear from additional sightings. The mitigation zone has been 
clear from any additional sightings for 10 min; or
    (4) Target transit. For activities using mobile targets, the 
intended target has transited a distance equal to double that of the 
mitigation zone size beyond the location of the last sighting.
    (b) Mitigation areas. In addition to procedural mitigation, Navy 
personnel must implement mitigation measures within mitigation areas to 
avoid or reduce potential impacts on marine mammals.
    (1) Mitigation areas for marine mammals in the Hawaii Range Complex 
for sonar, explosives, and vessel strikes--(i) Mitigation area 
requirements--(A) Hawaii Island Mitigation Area (year-round)--(1) MF1 
surface ship hull-mounted mid-frequency active sonar, MF4 dipping 
sonar, or explosives. Except as provided in paragraph (b)(1)(i)(A)(2) 
of this section, within the Hawaii Island Mitigation Area, Navy 
personnel must not conduct more than 300 hours of MF1 surface ship 
hull-mounted mid-frequency active sonar or 20 hours of MF4 dipping 
sonar annually, or use explosives that could potentially result in 
takes of marine mammals during training and testing.
    (2) National security exception. Should national security require 
conduct of more than 300 hours of MF1 surface ship hull-mounted mid-
frequency active sonar or 20 hours of MF4 dipping sonar, or use of 
explosives that could potentially result in the take of marine mammals 
during training or testing, Naval units must obtain permission from the 
appropriate designated Command authority prior to commencement of the 
activity. Navy personnel must provide NMFS with advance notification 
and include the information (e.g., sonar hours or explosives usage) in 
its annual activity reports submitted to NMFS.
    (B) 4-Islands Region Mitigation Area (November 15-April 15 for 
active sonar; year-round for explosives)--(1) MF1 surface ship hull-
mounted mid-frequency active sonar or explosives. Except as provided in 
paragraph (b)(1)(i)(B)(2) of this section, within the 4-Islands Region 
Mitigation Area, Navy personnel must not use MF1 surface ship hull-
mounted mid-frequency active sonar from November 15-April 15 or 
explosives that could potentially result in takes of marine mammals at 
any time during training and testing.
    (2) National security exception. Should national security require 
use of MF1 surface ship hull-mounted mid-frequency active sonar or 
explosives that could potentially result in the take of marine mammals 
during training or testing, Naval units must obtain permission from the 
appropriate designated Command authority prior to commencement of the 
activity. Navy personnel must provide NMFS with advance notification 
and include the information (e.g., sonar hours or explosives usage) in 
its annual activity reports submitted to NMFS.
    (C) Humpback Whale Special Reporting Areas (December 15-April 15). 
Navy personnel must report the total hours of surface ship hull-mounted 
mid-frequency active sonar used in the Humpback Whale Special Reporting 
Areas established from December 15-April 15 in its annual training and 
testing activity reports submitted to NMFS.
    (D) Humpback Whale Awareness Notification Message Area (November-
April). The following requirements apply in the Humpback Whale 
Awareness Notification Message Area established from November-April.
    (1) Seasonal awareness notification message. Navy personnel must 
issue a seasonal awareness notification message to alert ships and 
aircraft operating in the area to the possible presence of 
concentrations of large whales, including humpback whales.
    (2) Vessel instruction. To maintain safety of navigation and to 
avoid interactions with large whales during transits, Navy personnel 
must instruct vessels to remain vigilant to the presence of large whale 
species (including humpback whales).
    (3) Awareness notification message use. Platforms must use the 
information from the awareness notification message to assist their 
visual observation of applicable mitigation zones during training and 
testing activities and to aid in the implementation of procedural 
mitigation.
    (ii) [Reserved]
    (2) Mitigation areas for marine mammals in the southern California 
portion of the study area for sonar, explosives, and vessel strikes--
(i) Mitigation area requirements--(A) San Diego Arc, San Nicolas 
Island, and Santa Monica/Long Beach Mitigation Areas (June 1-October 
31)--(1) MF1 surface ship hull-mounted mid-frequency active sonar. 
Except as provided in paragraph (b)(2)(i)(A)(2) of this section, within 
the San Diego Arc, San Nicolas Island, and Santa Monica/Long Beach 
Mitigation Areas from June 1-October 31, Navy personnel must not 
conduct more than a total of 200 hours of MF1 surface ship hull-mounted 
mid-frequency active sonar in the combined areas, excluding normal 
maintenance and systems checks, during training and testing.
    (2) National security exception. Should national security require 
conduct of more than 200 hours of MF1 surface ship hull-mounted mid-
frequency active sonar in the combined areas during training and 
testing (excluding normal maintenance and systems checks), Naval units 
must obtain permission from the appropriate designated Command 
authority prior to commencement of the activity. Navy personnel must 
provide NMFS with advance notification and include the information 
(e.g., sonar hours) in its annual activity reports submitted to NMFS.
    (3) Explosives in San Diego Arc Mitigation Area. Except as provided 
in paragraph (b)(2)(i)(A)(4) of this section, within the San Diego Arc 
Mitigation Area, Navy personnel must not use explosives that could 
potentially result in the take of marine mammals during large-caliber 
gunnery, torpedo, bombing, and missile (including 2.75-inch rockets) 
activities during training and testing.
    (4) National security exception. Should national security require 
use of explosives that could potentially result in the take of marine 
mammals during large-caliber gunnery, torpedo, bombing, and missile 
(including 2.75-inch rockets) activities during training or testing 
within the San Diego Arc Mitigation Area, Naval units must obtain 
permission from the appropriate designated Command authority prior to 
commencement of the activity. Navy personnel must provide NMFS with 
advance notification and include the information (e.g., explosives 
usage) in its annual activity reports submitted to NMFS.
    (5) Explosives in San Nicolas Island Mitigation Area. Except as 
provided in paragraph (b)(2)(i)(A)(6) of this section, within the San 
Nicolas Island Mitigation Area, Navy personnel must not use explosives 
that could potentially result in the take of marine mammals during mine 
warfare, large-caliber gunnery, torpedo, bombing, and missile 
(including 2.75-inch rockets) activities during training.
    (6) National security exception. Should national security require 
use of explosives that could potentially result in the take of marine 
mammals during mine warfare, large-caliber gunnery,

[[Page 5026]]

torpedo, bombing, and missile (including 2.75-inch rockets) activities 
during training in the San Nicolas Island Mitigation Area, Naval units 
must obtain permission from the appropriate designated Command 
authority prior to commencement of the activity. Navy personnel must 
provide NMFS with advance notification and include the information 
(e.g., explosives usage) in its annual activity reports submitted to 
NMFS.
    (7) Explosives in the Santa Monica/Long Beach Mitigation Area. 
Except as provided in paragraph (b)(2)(i)(A)(8) of this section, within 
the Santa Monica/Long Beach Mitigation Area, Navy personnel must not 
use explosives that could potentially result in the take of marine 
mammals during mine warfare, large-caliber gunnery, torpedo, bombing, 
and missile (including 2.75-inch rockets) activities during training 
and testing.
    (8) National security exception. Should national security require 
use of explosives that could potentially result in the take of marine 
mammals during mine warfare, large-caliber gunnery, torpedo, bombing, 
and missile (including 2.75-inch rockets) activities during training or 
testing in the Santa Monica/Long Beach Mitigation Area, Naval units 
must obtain permission from the appropriate designated Command 
authority prior to commencement of the activity. Navy personnel must 
provide NMFS with advance notification and include the information 
(e.g., explosives usage) in its annual activity reports submitted to 
NMFS.
    (B) Santa Barbara Island Mitigation Area (year-round)--(1) MF1 
surface ship hull-mounted mid-frequency active sonar or explosives. 
Except as provided in paragraph (b)(2)(i)(B)(2) of this section, within 
the Santa Barbara Island Mitigation Area, Navy personnel must not use 
MF1 surface ship hull-mounted mid-frequency active sonar during 
training or testing, or explosives that could potentially result in the 
take of marine mammals during medium-caliber or large-caliber gunnery, 
torpedo, bombing, and missile (including 2.75-inch rockets) activities 
during training.
    (2) National security exception. Should national security require 
use of MF1 surface ship hull-mounted mid-frequency active sonar during 
training or testing, or explosives that could potentially result in the 
take of marine mammals during medium-caliber or large-caliber gunnery, 
torpedo, bombing, and missile (including 2.75-inch rockets) activities 
during training, Naval units must obtain permission from the 
appropriate designated Command authority prior to commencement of the 
activity. Navy personnel must provide NMFS with advance notification 
and include the information (e.g., sonar hours or explosives usage) in 
its annual activity reports submitted to NMFS.
    (C) Spring Large Whale Awareness Notification Message--(1) 
Awareness notification message. Navy personnel must issue an awareness 
notification message during the spring to alert ships and aircraft 
within the eastern Pacific to the possible presence of concentrations 
of large whales, including blue whales, fin whales, and humpback 
whales.
    (2) Applicable period. This message must apply to a period that is 
based on predicted oceanographic conditions for a given year.
    (3) Marine mammals and vessel transit. To maintain safety of 
navigation and to avoid interactions with large whales during transits, 
Navy personnel must instruct personnel on vessels that when a marine 
mammal is spotted, this may be an indicator that additional marine 
mammals are present nearby, and increased vigilance and awareness of 
Navy personnel is warranted.
    (4) Platform use of message. Platforms must use the information 
from the awareness notification messages to assist their visual 
observation of applicable mitigation zones during training and testing 
activities and to aid in the implementation of procedural mitigation.
    (D) Gray Whale (November-March) and Fin Whale (November-May) 
Awareness Notification Message Areas. The following requirements apply 
in the Gray Whale Awareness Notification Areas from November-March and 
Fin Whale Awareness Notification Message Areas from November-May.
    (1) Seasonal awareness message. Navy personnel must issue a 
seasonal awareness notification message to alert ships and aircraft 
operating in the area to the possible presence of concentrations of 
large whales, including gray whales, and fin whales.
    (2) Marine mammals and vessel transit. To maintain safety of 
navigation and to avoid interactions with large whales during transits, 
Navy personnel must instruct personnel on vessels to remain vigilant to 
the presence of large whale species.
    (3) Platform use of message. Platforms must use the information 
from the awareness notification messages to assist their visual 
observation of applicable mitigation zones during training and testing 
activities and to aid in the implementation of procedural mitigation.
    (ii) [Reserved]


Sec.  218.75   Requirements for monitoring and reporting.

    (a) Unauthorized take. Navy personnel must notify NMFS immediately 
(or as soon as operational security considerations allow) if the 
specified activity identified in Sec.  218.70 is thought to have 
resulted in the mortality or serious injury of any marine mammals, or 
in any Level A harassment or Level B harassment of marine mammals not 
identified in Sec.  218.72(b).
    (b) Monitoring and reporting under the LOAs. The Navy must conduct 
all monitoring and reporting required under the LOAs. Details on 
program goals, objectives, project selection process, and current 
projects are available at www.navymarinespeciesmonitoring.us.
    (c) Notification of injured, live stranded, or dead marine mammals. 
The Navy must comply with all notification and reporting requirements 
under the LOAs. The Notification and Reporting Plan, which sets out 
notification, reporting, and other requirements when dead, injured, or 
live stranded marine mammals are detected. The Notification and 
Reporting Plan is available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
    (d) Changes in Lookout policies. The Navy must report changes in 
its Lookout policies to NMFS as soon as practicable after a change is 
made.
    (e) Annual HSTT Study Area marine species monitoring report. The 
Navy must submit an annual report of the HSTT Study Area monitoring 
describing the implementation and results from the previous calendar 
year. Data collection methods must be standardized across range 
complexes and study areas to allow for comparison in different 
geographic locations. The report must be submitted to the Director, 
Office of Protected Resources, NMFS, either within 3 months after the 
end of the calendar year, or within 3 months after the conclusion of 
the monitoring year, to be determined by the Adaptive Management 
process. This report will describe progress of knowledge made with 
respect to intermediate scientific objectives within the HSTT Study 
Area associated with the Integrated Comprehensive Monitoring Program 
(ICMP). Similar study questions must be treated together so that 
progress on each topic can be summarized across all Navy ranges. The 
report need not include analyses and content that does not provide 
direct assessment of cumulative progress on the monitoring plan study 
questions. As an alternative,

[[Page 5027]]

the Navy may submit a multi-Range Complex annual Monitoring Plan report 
to fulfill this requirement. Such a report will describe progress of 
knowledge made with respect to monitoring study questions across 
multiple Navy ranges associated with the ICMP. Similar study questions 
must be treated together so that progress on each topic can be 
summarized across multiple Navy ranges. The report need not include 
analyses and content that does not provide direct assessment of 
cumulative progress on the monitoring study question. This will 
continue to allow the Navy to provide a cohesive monitoring report 
covering multiple ranges (as per ICMP goals), rather than entirely 
separate reports for the HSTT, Gulf of Alaska, Mariana Islands, and 
Northwest Study Areas.
    (f) Annual HSTT Study Area training exercise report and testing 
activity report. Each year, the Navy must submit two preliminary 
reports (Quick Look Report) detailing the status of authorized sound 
sources within 21 days after the anniversary of the date of issuance of 
each LOA to the Director, Office of Protected Resources, NMFS. Each 
year, the Navy must submit detailed reports to the Director, Office of 
Protected Resources, NMFS, within 3 months after the 1-year anniversary 
of the date of issuance of the LOA. The HSTT annual Training Exercise 
Report and Testing Activity Report can be consolidated with other 
exercise reports from other range complexes in the Pacific Ocean for a 
single Pacific Exercise Report, if desired. The annual reports must 
contain information on major training exercises (MTEs), Sinking 
Exercise (SINKEX) events, and a summary of all sound sources used, 
including within specific mitigation reporting areas, as described in 
paragraphs (f)(3) through (5) of this section. The analysis in the 
detailed reports must be based on the accumulation of data from the 
current year's report and data collected from previous reports. The 
detailed reports must contain information identified in paragraphs 
(f)(1) through (9) of this section.
    (1) MTEs. This section of the report must contain the following 
information for MTEs conducted in the HSTT Study Area.
    (i) Exercise information (for each MTE).
    (A) Exercise designator.
    (B) Date that exercise began and ended.
    (C) Location.
    (D) Number and types of active sonar sources used in the exercise.
    (E) Number and types of passive acoustic sources used in exercise.
    (F) Number and types of vessels, aircraft, and other platforms 
participating in each exercise.
    (G) Total hours of all active sonar source operation.
    (H) Total hours of each active sonar source bin.
    (I) Wave height (high, low, and average) during exercise.
    (ii) Individual marine mammal sighting information for each 
sighting in each exercise where mitigation was implemented:
    (A) Date, time, and location of sighting.
    (B) Species (if not possible, indication of whale/dolphin/
pinniped).
    (C) Number of individuals.
    (D) Initial Detection Sensor (e.g., sonar, Lookout).
    (E) Indication of specific type of platform observation was made 
from (including, for example, what type of surface vessel or testing 
platform).
    (F) Length of time observers maintained visual contact with marine 
mammal.
    (G) Sea state.
    (H) Visibility.
    (I) Sound source in use at the time of sighting.
    (J) Indication of whether animal was less than 200 yd (182.9 m), 
200 to 500 yd (182.9 to 457.2 m), 500 to 1,000 yd (457.2 m to 914.4 m), 
1,000 to 2,000 yd (914.4 m to 1,828.8 m), or greater than 2,000 yd 
(1,828.8 m) from sonar source.
    (K) Whether operation of sonar sensor was delayed, or sonar was 
powered or shut down, and the length of the delay.
    (L) If source in use was hull-mounted, true bearing of animal from 
the vessel, true direction of vessel's travel, and estimation of 
animal's motion relative to vessel (opening, closing, parallel).
    (M) Lookouts must report, in plain language and without trying to 
categorize in any way, the observed behavior of the animal(s) (such as 
animal closing to bow ride, paralleling course/speed, floating on 
surface and not swimming, etc.) and if any calves were present.
    (iii) An evaluation (based on data gathered during all of the MTEs) 
of the effectiveness of mitigation measures designed to minimize the 
received level to which marine mammals may be exposed. This evaluation 
must identify the specific observations that support any conclusions 
the Navy reaches about the effectiveness of the mitigation.
    (2) SINKEXs. This section of the report must include the following 
information for each SINKEX completed that year.
    (i) Exercise information (gathered for each SINKEX).
    (A) Location.
    (B) Date and time exercise began and ended.
    (C) Total hours of observation by Lookouts before, during, and 
after exercise.
    (D) Total number and types of explosive source bins detonated.
    (E) Number and types of passive acoustic sources used in exercise.
    (F) Total hours of passive acoustic search time.
    (G) Number and types of vessels, aircraft, and other platforms 
participating in exercise.
    (H) Wave height in feet (high, low, and average) during exercise.
    (I) Narrative description of sensors and platforms utilized for 
marine mammal detection and timeline illustrating how marine mammal 
detection was conducted.
    (ii) Individual marine mammal observation (by Navy Lookouts) 
information for each sighting where mitigation was implemented.
    (A) Date/Time/Location of sighting.
    (B) Species (if not possible, indicate whale, dolphin, or 
pinniped).
    (C) Number of individuals.
    (D) Initial detection sensor (e.g., sonar or Lookout).
    (E) Length of time observers maintained visual contact with marine 
mammal.
    (F) Sea state.
    (G) Visibility.
    (H) Whether sighting was before, during, or after detonations/
exercise, and how many minutes before or after.
    (I) Distance of marine mammal from actual detonations (or target 
spot if not yet detonated): Less than 200 yd (182.9 m), 200 to 500 yd 
(182.9 to 457.2 m), 500 to 1,000 yd (457.2 m to 914.4 m), 1,000 to 
2,000 yd (914.4 m to 1,828.8 m), or greater than 2,000 yd (1,828.8 m).
    (J) Lookouts must report, in plain language and without trying to 
categorize in any way, the observed behavior of the animal(s) (such as 
animal closing to bow ride, paralleling course/speed, floating on 
surface and not swimming etc.), including speed and direction and if 
any calves were present.
    (K) The report must indicate whether explosive detonations were 
delayed, ceased, modified, or not modified due to marine mammal 
presence and for how long.
    (L) If observation occurred while explosives were detonating in the 
water, indicate munition type in use at time of marine mammal 
detection.
    (3) Summary of sources used. This section of the report must 
include the following information summarized from the authorized sound 
sources used in all training and testing events:

[[Page 5028]]

    (i) Total annual hours or quantity (per the LOA) of each bin of 
sonar or other acoustic sources (e.g., pile driving and air gun 
activities); and
    (ii) Total annual expended/detonated ordinance (missiles, bombs, 
sonobuoys, etc.) for each explosive bin.
    (4) Humpback Whale Special Reporting Area (December 15-April 15). 
The Navy must report the total hours of operation of surface ship hull-
mounted mid-frequency active sonar used in the Humpback Whale Special 
Reporting Area.
    (5) Mitigation areas. The Navy must report any use of restricted 
acoustic and explosive sources identified in Sec.  218.74(b). 
Information included in the classified annual reports may be used to 
inform future adaptive management of activities within the HSTT Study 
Area.
    (6) Geographic information presentation. The reports must present 
an annual (and seasonal, where practical) depiction of training and 
testing bin usage (as well as pile driving activities) geographically 
across the HSTT Study Area.
    (7) Sonar exercise notification. The Navy must submit to NMFS 
(contact as specified in the LOA) an electronic report within 15 
calendar days after the completion of any MTE indicating:
    (i) Location of the exercise;
    (ii) Beginning and end dates of the exercise; and
    (iii) Type of exercise.
    (8) Large whale aggregations. For each instance that an aggregation 
of large whales (4 or more whales within 1 nmi (1.9 km)) is reported in 
the area between 32-33 degrees North and 117.2-119.5 degrees West, Navy 
personnel must report the following information and to the extent 
practicable, this information should be provided in the Navy's 
unclassified version of these reports:
    (i) Date, time, and general location (e.g., approximately 10-12 nmi 
(18.5 to 22.2 km) Southeast of San Clemente Island) of the whales when 
the aggregation was first sighted
    (ii) Total number of whales observed within 1 nmi (1.9 km) of a 
Navy vessel that make up the aggregation
    (iii) Approximate distance (or distances if more than 1 group of 
whales is sighted) of the vessel from the whales in the aggregation 
when the whales were first sighted.
    (9) Foreign military sonar and explosives. 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 U.S. Navy's 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.
    (g) 7-year close-out comprehensive training and testing activity 
report. This report must be included as part of the 2025 annual 
training and testing report. This report must provide the annual totals 
for each sound source bin with a comparison to the annual allowance and 
the 7-year total for each sound source bin with a comparison to the 7-
year allowance. Additionally, if there were any changes to the sound 
source allowance, this report must include a discussion of why the 
change was made and include the analysis to support how the change did 
or did not result in a change in the 2018 HSTT FEIS/OEIS and final rule 
determinations. The draft report must be submitted within 3 months 
after the expiration of this subpart to the Director, Office of 
Protected Resources, NMFS. NMFS must submit comments on the draft 
close-out report, if any, within 3 months of receipt. The report will 
be considered final after the Navy has addressed NMFS' comments, or 3 
months after the submittal of the draft if NMFS does not provide 
comments.


Sec.  218.76  Letters of Authorization (LOA).

    (a) To incidentally take marine mammals pursuant to the regulations 
in this subpart, the Navy must apply for and obtain LOAs in accordance 
with Sec.  216.106 of this chapter.
    (b) LOAs, unless suspended or revoked, may be effective for a 
period of time not to exceed December 20, 2025.
    (c) If an LOA expires prior to December 20, 2025, the Navy may 
apply for and obtain a renewal of the LOA.
    (d) In the event of projected changes to the activity or to 
mitigation, monitoring, or reporting (excluding changes made pursuant 
to the adaptive management provision of Sec.  218.77(c)(1)) required by 
an LOA issued under this subpart, the Navy must apply for and obtain a 
modification of the LOA as described in Sec.  218.77.
    (e) Each LOA must set forth:
    (1) Permissible methods of incidental taking;
    (2) Geographic areas for incidental taking;
    (3) Means of effecting the least practicable adverse impact (i.e., 
mitigation) on the species or stocks of marine mammals and their 
habitat; and
    (4) Requirements for monitoring and reporting.
    (f) Issuance of the LOA(s) must be based on a determination that 
the level of taking is consistent with the findings made for the total 
taking allowable under the regulations in this subpart.
    (g) Notice of issuance or denial of the LOA(s) must be published in 
the Federal Register within 30 days of a determination.


Sec.  218.77  Renewals and modifications of Letters of Authorization.

    (a) An LOA issued under Sec. Sec.  216.106 of this chapter and 
218.76 for the activity identified in Sec.  218.70(c) may be renewed or 
modified upon request by the applicant, provided that:
    (1) The planned specified activity and mitigation, monitoring, and 
reporting measures, as well as the anticipated impacts, are the same as 
those described and analyzed for the regulations in this subpart 
(excluding changes made pursuant to the adaptive management provision 
in paragraph (c)(1) of this section); and
    (2) NMFS determines that the mitigation, monitoring, and reporting 
measures required by the previous LOA(s) were implemented.
    (b) For LOA modification or renewal requests by the applicant that 
include changes to the activity or to the mitigation, monitoring, or 
reporting measures (excluding changes made pursuant to the adaptive 
management provision in paragraph (c)(1) of this section) that do not 
change the findings made for the regulations or result in no more than 
a minor change in the total estimated number of takes (or distribution 
by species or stock or years), NMFS may publish a notice of planned LOA 
in the Federal Register, including the associated analysis of the 
change, and solicit public comment before issuing the LOA.
    (c) An LOA issued under Sec. Sec.  216.106 of this chapter and 
218.76 may be modified by NMFS under the following circumstances:
    (1) After consulting with the Navy regarding the practicability of 
the modifications, NMFS may modify (including adding or removing 
measures) the existing mitigation, monitoring, or reporting measures if 
doing so creates a reasonable likelihood of more effectively 
accomplishing the goals of the mitigation and monitoring.
    (i) Possible sources of data that could contribute to the decision 
to modify the mitigation, monitoring, or reporting measures in an LOA 
include:
    (A) Results from the Navy's monitoring from the previous year(s);
    (B) Results from other marine mammal and/or sound research or 
studies; or
    (C) Any information that reveals marine mammals may have been taken 
in a manner, extent, or number not authorized by the regulations in 
this subpart or subsequent LOAs.

[[Page 5029]]

    (ii) If, through adaptive management, the modifications to the 
mitigation, monitoring, or reporting measures are substantial, NMFS 
will publish a notice of planned LOA in the Federal Register and 
solicit public comment.
    (2) If NMFS determines that an emergency exists that poses a 
significant risk to the well-being of the species or stocks of marine 
mammals specified in LOAs issued pursuant to Sec. Sec.  216.106 of this 
chapter and 218.76, an LOA may be modified without prior notice or 
opportunity for public comment. Notice would be published in the 
Federal Register within 30 days of the action.


Sec. Sec.  218.78-218.79  [Reserved]

[FR Doc. 2024-31402 Filed 1-8-25; 4:15 pm]
BILLING CODE 3510-22-P`