Proposed Rule2023-21499
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
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
October 3, 2023
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the U.S. Navy (Navy) to modify the regulations and Letters of Authorization (LOAs) authorizing the take of marine mammals incidental to Navy 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 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 following the May 2023 strike and proposes to authorize 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). Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on the proposed promulgation of modified regulations and associated LOAs for the Navy governing this additional incidental taking of marine mammals. NMFS will consider public comments prior to issuing any final rule and making final decisions on the issuance of the requested LOAs. Agency responses to public comments will be provided in the notice of the final decision. The Navy's activities qualify as military readiness activities pursuant to the MMPA, as amended by the National Defense Authorization Act for Fiscal Year 2004 (2004 NDAA).
Full Text
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[Federal Register Volume 88, Number 190 (Tuesday, October 3, 2023)]
[Proposed Rules]
[Pages 68290-68367]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-21499]
[[Page 68289]]
Vol. 88
Tuesday,
No. 190
October 3, 2023
Part II
Department of Commerce
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National Oceanic and Atmospheric Administration
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50 CFR Part 218
Taking and Importing Marine Mammals; Taking Marine Mammals Incidental
to the U.S. Navy Training and Testing Activities in the Hawaii-Southern
California Training and Testing Study Area; Proposed Rule
Federal Register / Vol. 88 , No. 190 / Tuesday, October 3, 2023 /
Proposed Rules
[[Page 68290]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 218
[Docket No. 230817-0197]
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: Proposed rule; request for comments and information.
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SUMMARY: NMFS has received a request from the U.S. Navy (Navy) to
modify the regulations and Letters of Authorization (LOAs) authorizing
the take of marine mammals incidental to Navy 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 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 following the May 2023
strike and proposes to authorize 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). Pursuant to the Marine Mammal
Protection Act (MMPA), NMFS is requesting comments on the proposed
promulgation of modified regulations and associated LOAs for the Navy
governing this additional incidental taking of marine mammals. NMFS
will consider public comments prior to issuing any final rule and
making final decisions on the issuance of the requested LOAs. Agency
responses to public comments will be provided in the notice of the
final decision. The Navy's activities qualify as military readiness
activities pursuant to the MMPA, as amended by the National Defense
Authorization Act for Fiscal Year 2004 (2004 NDAA).
DATES: Comments and information must be received no later than November
17, 2023.
ADDRESSES: Submit all electronic public comments via the Federal e-
Rulemaking Portal. Go to <a href="https://www.regulations.gov">https://www.regulations.gov</a> and enter NOAA-
NMFS-2023-0102 in the Search box. Click on the ``Comment'' icon,
complete the required fields, and enter or attach your comments.
Instructions: Comments sent by any other method, to any other
address or individual, or received after the end of the comment period
may not be considered by NMFS. All comments received are a part of the
public record and will generally be posted for public viewing on
<a href="http://www.regulations.gov">www.regulations.gov</a> without change. All personal identifying
information (e.g., name, address), confidential business information,
or otherwise sensitive information submitted voluntarily by the sender
will be publicly accessible. NMFS will accept anonymous comments (enter
``N/A'' in the required fields if you wish to remain anonymous).
A copy of the Navy's applications, NMFS' proposed and final rules
and subsequent LOAs for the existing (2020) and previous (2018)
regulations, and other supporting documents and documents cited herein
may be obtained online at: <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities">www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities</a>. 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 proposed regulations, issued under the authority of the MMPA
(16 U.S.C. 1361 et seq.), would modify the current 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 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. The current HSTT regulations and LOAs
authorize 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 proposes to authorize 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 proposed activities remain unchanged; however, this
proposed rule includes two additional mitigation measures and revision
of two existing mitigation measures to further reduce the probability
of vessel strike. With the exception of these new mitigation measures
and revisions to two existing mitigation measures, the required
mitigation and monitoring measures remain unchanged.
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 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.
An authorization for incidental takings shall be granted if NMFS
finds that the taking will have a negligible impact on the species or
stock(s) 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
[[Page 68291]]
similar significance, and on the availability of such species or stocks
for taking for certain subsistence uses (referred to in this rulemaking
as ``mitigation measures''); and requirements pertaining to the
monitoring and reporting of such takings. The MMPA defines ``take'' to
mean to harass, hunt, capture, or kill, or attempt to harass, hunt,
capture, or kill any marine mammal. The Preliminary Analysis and
Negligible Impact Determination section below discusses the definition
of ``negligible impact.''
The 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 regulations 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 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 proposes no changes to the
nature of the specified activities covered by the 2020 HSTT final rule.
The Navy states 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 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:
<a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities</a>. 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
proposed rule cover training and testing activities that would occur
over the remainder of the effective period of the current regulations,
valid from the
[[Page 68292]]
publication date of the final rule, if issued, through December 20,
2025.
Summary of the Proposed Regulations
NMFS is proposing to modify 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 current regulations). In its 2022
application, the Navy proposes no additional changes and explains that
its training and testing activities, including the level of vessel use,
remain unchanged. Nearly all mitigation, monitoring, and reporting
measures remain unchanged with the exception of two additional
mitigation measures, revision of two existing mitigation measures, and
an additional reporting measure resulting from discussions between the
Navy and NMFS.
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 propose
authorizing 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 consider authorizing these additional takes after analyzing
the best available 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 propose
requiring new and modified mitigation and also consider whether to
require any new or modified mitigation for the entire specified
activity.
The proposed regulatory language included at the end of this
proposed rule, which would be 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 a new reporting
measure. Therefore, in this proposed 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
proposed rule. The list indicates the short name by which the document
is referenced in this proposed rule as well as the full titles of the
cited documents. All of the documents can be found at:
<a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities">www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities</a> and <a href="http://www.hstteis.com/">http://www.hstteis.com/</a>.
<bullet> NMFS June 26, 2018, Hawaii-Southern California Training
and Testing (HSTT) proposed rule (83 FR 29872; 2018 HSTT proposed
rule);
<bullet> NMFS December 27, 2018, Hawaii-Southern California
Training and Testing (HSTT) final rule (83 FR 66846; 2018 HSTT final
rule);
<bullet> NMFS September 13, 2019, Hawaii-Southern California
Training and Testing (HSTT) proposed rule (84 FR 48388; 2019 HSTT
proposed rule);
<bullet> NMFS July 10, 2020, Hawaii-Southern California Training
and Testing (HSTT) final rule (85 FR 41780; 2020 HSTT final rule);
<bullet> Navy October 13, 2017, MMPA rulemaking and LOA application
(2017 Navy application);
<bullet> Navy March 11, 2019, MMPA rulemaking and LOA extension
application (2019 Navy application);
<bullet> Navy March 31, 2022, MMPA rulemaking and LOA revision
application (2022 Navy application); and
<bullet> 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 requests 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 (<a href="http://www.hstteis.com/">http://www.hstteis.com/</a>). Each military training and testing
activity described meets mandated Fleet requirements to deploy ready
forces. The Navy proposes no changes to the specified activities
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 proposed 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 proposed 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
[[Page 68293]]
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 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
such as launch and recovery of a small rigid hull inflatable boat;
vessel boarding, search, and seizure training events; or retrieval of a
target when vessels would be dead in the water or moving slowly ahead
to maintain steerage. There are a few specific events, including high-
speed tests of newly constructed vessels, where vessels would operate
at higher speeds. 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 proposes 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
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 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 (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
[[Page 68294]]
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 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). Even in a RIMPAC
year, the days at sea for foreign militaries engaged in a Navy-led
training or testing activity accounts for a very small 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).
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 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.
If a foreign military is not participating in a U.S. Navy training or
testing exercise, foreign military vessels operating within the HSTT
Study Area are expected to adhere to their own standard operating
procedures and environmental mitigation measures.
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 in
two ways. 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 SARs. Second,
NMFS considers foreign military activities, including recent strikes,
qualitatively in this proposed 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 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. Finally, 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 take proposed for authorization, as part of the negligible impact
analysis.
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 standard operating procedures are essential
to safety and mission success, the Navy considers them to be part of
the proposed activities under NEPA and included them in the
environmental analysis. We consider standard operating procedures 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 standard operating procedures 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 Proposed 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 Proposed Mitigation Measures section (September
2022).
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,
[[Page 68295]]
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 proposed for authorization.
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), biologically important areas
(BIAs), national marine sanctuaries (NMSs), and unusual 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 Distinct Population Segment (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 proposed regulations.
NMFS has reviewed the 2022 final Stock Assessment Reports (SARs;
Carretta et al. 2023, Young et al. 2023). For all species except
humpback whale, NMFS determined that neither the SARs nor any other new
information changes our determination of which species or stocks have
the potential to be affected by the Navy's activities. For humpback
whale, 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 proposed
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 2022 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, in which case, 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 -- 602 (0.22)/501.
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 Mexico-- California 1,284.
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 -- 519 (0.40)/374.
borealis. Pacific. Depleted California
Hawaii........... Strategic, Endangered Hawaii Summer 391 (0.9)/204.
Depleted
[[Page 68296]]
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
Sperm whale................... Physeter CA/OR/WA......... Strategic, Endangered Southern -- 1,997 (0.57)/
macrocephalus. Depleted California 1,270.
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 (0.53)/
California 894.
Blainville's beaked whale..... Mesoplodon Hawaii........... -- -- Hawaii -- 1,132 (0.99)/
densirostris. 564.
Cuvier's beaked whale......... 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 Offshore -- -- Southern -- 3,477 (0.696)/
California 2,048.
Hawaii Pelagic... -- -- Hawaii -- unknown.
Kauai and Niihau. -- -- Hawaii -- NA NA/97.
Oahu............. -- -- Hawaii -- NA.
4-Islands........ -- -- Hawaii -- NA.
Hawaii Island.... -- -- Hawaii -- unknown.
False killer whale............ Pseudorca Main Hawaiian Strategic, Endangered Hawaii -- 167 (0.14)/149.
crassidens. Islands Insular. Depleted
Hawaii Pelagic... -- -- Hawaii -- 2,086 (0.35)/
1,567.
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 Offshore. California
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.
4-Islands........ -- -- Hawaii -- unknown.
Hawaii Island.... -- -- Hawaii -- unknown.
Hawaii Pelagic... -- -- Hawaii -- 39,768 (0.51)/
25,548.
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)/
Hawaii........... -- -- California -- 4,817.
Hawaii 7,385 (0.22)/
6,150.
Steno bredanensis NSD \2\.......... -- -- Southern -- unknown.
California
Rough-toothed dolphin......... Hawaii........... -- -- Hawaii -- 76,357 (0.41)/
54,804.
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 -- 12,607 (0.18)/
10,847.
Spinner dolphin............... Stenella Hawaii Pelagic... -- -- Hawaii -- unknown.
longirostris.
Hawaii Island.... -- -- Hawaii -- 665 (0.09)/617.
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.
[[Page 68297]]
Hawaii........... -- -- Hawaii -- 35,179 (0.23)/
29,058.
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 -- 1,465 \3\ (0.03)/
schauinslandi. Depleted 1,431.
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\ 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.
\3\ The best official estimate of the total population size from the NMFS 2022 Stock Assessment Report (Carretta et al. 2023) is 1,465. This estimate is
based on available data through 2020 data for Kure and Midway Atolls, Nihoa Island, and the MHI, and through 2019 for all other subpopulations. More
recent survey data for 2021 and 2022 indicate an increasing trend in population size. NMFS estimates a total population size for 2022 of 1,605 (NOAA
2023).
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.
There is one UME that is applicable to our evaluation of the Navy's
activities in the HSTT Study Area. The gray whale UME along the west
coast of North America is active and involves ongoing investigations.
At the time of publication of the 2020 HSTT final rule, there was an
active UME for Guadalupe fur seal, which NMFS fully considered in its
analysis (85 FR 41780, July 10, 2020). This UME was closed on September
2, 2021, and therefore, it is not discussed further beyond the
information provided here. The UME was closed because conditions under
which the UME was declared are no longer occurring or have become
persistent. Scientists documented a reduction in strandings compared to
peak UME years. The team of scientists who investigated this UME
determined the cause of the UME as being due to malnutrition in
Guadalupe fur seal pups and yearlings from ecological factors (e.g.,
warm water events) in the Pacific Ocean causing suboptimal prey
conditions. Please see <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/unusual-mortality-event-2015-2021-guadalupe-fur-seal-and-2015">https://www.fisheries.noaa.gov/national/marine-life-distress/unusual-mortality-event-2015-2021-guadalupe-fur-seal-and-2015</a> for additional information on this UME.
Gray Whale UME
Since January 1, 2019, elevated gray whale strandings have occurred
along the west coast of North America, from Mexico to Canada. As of
June 25, 2023, there have been a total of 674 strandings along the
coasts of the U.S., Canada, and Mexico, with 333 of those strandings
occurring along the U.S. coast. Of the strandings on the U.S. coast,
135 have occurred in Alaska, 83 in Washington, 22 in Oregon, and 93 in
California. Full or partial necropsy examinations were conducted on a
subset of the whales. Preliminary findings in several of the whales
have shown evidence of emaciation. These findings are not consistent
across all of the whales examined, so more research is needed. As part
of the UME investigation process, NOAA has assembled an independent
team of scientists to coordinate with the Working Group on Marine
Mammal Unusual Mortality Events to review the data collected, sample
stranded whales, consider possible causal-linkages between the
mortality event and recent ocean and ecosystem perturbations, and
determine the next steps for the investigation. Please refer to:
<a href="https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2023-gray-whale-unusual-mortality-event-along-west-coast-and">https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2023-gray-whale-unusual-mortality-event-along-west-coast-and</a> for more
information on this UME. See the Preliminary Analysis and Negligible
Impact Determination section for additional information on how NMFS has
considered this UME in this proposed rule.
Biologically Important Areas
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, Cuvier's
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.
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 Negligible Impact Analysis and
Determination section considers the content of this section, the
Estimated Take section, and the Proposed Mitigation section, to draw
conclusions regarding the likely impacts of these activities on the
reproductive success or survivorship of individuals and 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
[[Page 68298]]
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), physiological responses (particularly
stress responses), behavioral disturbance, or habitat effects. We do
not repeat the information here, all of which remains current and
applicable, and instead summarize any new relevant information from the
scientific literature. For more information we 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 mid-frequency active sonar (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
continuous active sonar (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 pulsed active sonar (PAS) and CAS at
similar cumulative Sound Exposure Levels (SEL<INF>cum</INF>), 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).
New Pertinent Science Since Publication of the 2020 HSTT Final Rule
NMFS has reviewed 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
2020 HSTT final rule are presented below. The literature generally
falls into the following topic areas: Vessel Strike; Aircraft Noise;
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
Crum et al. (2019) analyzed a modeling framework using encounter
theory to estimate the risk of lethal commercial vessel strike to North
Atlantic right whales. Seasonal mortality rates of right whales
decreased by 22 percent on average after a speed rule was implemented,
indicating that the rule is effective at reducing lethal collisions.
The rule's effect on risk was greatest where right whales were abundant
and vessel traffic was heavy but varied considerably across time and
space.
Keen et al. (2019) compared vessel traffic patterns in the Southern
California Bight, San Francisco, and the Pacific Northwest and found
fin whales had a higher risk of nighttime vessel strikes with the
nighttime risk being double daytime risk. The authors concluded that
the shipping lanes contained 14 percent of all traffic volume and
contributed 13 percent of all strike risk similar to conclusions
reached by Rockwood et al. (2017). However, the authors also point out
that a California Current Ecosystem (CCE) wide shipping speed
reductions would not be practicable. Instead, they proposed 24-hour
speed restrictions around and within shipping lanes would be more
effective and feasible than nighttime only speed restrictions
elsewhere. Keen et al. (2019b) reported high fin whale habitat
suitability throughout the Southern California Bight, in particular
inshore in winter and in southern portions of the Bight, which include
HSTT SOCAL Study Area.
Leaper (2019) estimated that a global 10 percent reduction in
shipping speeds could result in a reduction of underwater sound
associated with shipping by approximately 40 percent and vessel strike
risk by around 50 percent by 2050. The vessel strike risk reduction
done by the author is highly variable based solely on the relationship
between ship speed and risk, qualitative in its findings, and
speculative.
Redfern et al. (2019) compared risk of vessel strike to baleen
whales around the Santa Barbara Channel based on 8 years of shipping
data (2008-2015). Species evaluated include blue whales, fin whales,
and humpback whales using available spatial habitat models and
satellite tagging results. Spatial habitat modeling data included the
years 1991, 1993, 1996, 2001, 2005, 2008, and 2009. The authors defined
collision risk based on the co-occurrence of whales and ships for
various management scenarios focused on adding shipping routes,
expanding existing area to be avoided, and reducing shipping speed
associated with these areas. Encounter rate theory was used to predict
relative mortality resulting from vessel strikes by estimating (a) the
encounter rate; (b) the number of encounters that result in a
collision; and (c) the probability that a collision is lethal (Martin
et al. 2016, Rockwood et al. 2017, Crum et al. 2019). The authors
concluded that expanding the existing areas to be avoided and speed
reductions within shipping lanes and their approaches would be the most
effective solutions. Ship speeds declined in the Bight from 2008 to
2015 because California air pollution regulations and economic factors
made slow[hyphen]steaming strategies more favorable, therefore
reduction in risk from slowing ships was greatest in 2008 and lowest in
2015.
Rockwood and Jahncke (2019) estimated that humpback whale mortality
from January to April in Southern California alone was 6.5 whales
(1.63/month), based upon modeling using updated abundance
[[Page 68299]]
estimates for humpback whales off Southern California. When added to
the estimated mortality from July to November, the total estimated
annual humpback mortality from vessel strikes in California alone was
23.4 deaths (16.9 + 6.5). This study did not include information for
January to April for fin or blue whales and did not estimate humpback
mortality in central or Northern California. Thus, even this updated
study may underestimate whale mortality. The author's focus was
exclusively on shipping approaches to San Francisco Bay (Northern
California) and Los Angeles/Long Beach (Southern California) based on
Rockwood et al. 2017 with new local fine scale analysis. The paper
postulated potential mortality from models, not actual reported
strikes. The model is used to predict whale mortality based on factors
listed in Rockwood et al. 2017. In the model results, cargo vessels,
especially container ships, accounted for more than half of the
predicted mortality for all whale species in both Northern and Southern
California with oil tankers accounting for the second highest
mortality. The author's recommendation concludes with commercial
industry-wide shipping speed reduction recommendations given the model
is biased on mortality as a function of speed. In summary, Rockwood and
Jahncke (2019) only addresses commercial shipping strike risk
associated with major California commercial ports, and therefore, the
paper may have limited applicability to how the Navy trains and tests
in SOCAL.
S[egrave]be et al. (2019) assesses previous publications on whale
vessel strike risk methodology and proposed a systematic approach to
addressing the issue called the Formal Safety Assessment: (1)
identification of hazards, (2) assessment of risks, (3) risk control
options, (4) cost-benefit assessment, and (5) recommendations for
decision-making. The authors provided a case study based on data from
Rockwood et al. (2017). No new data analysis is presented in the paper.
Caveats to S[egrave]be et al. (2019) are similar to those mentioned for
Rockwood et al. (2017, 2019): older marine mammal data that may not be
reflective of current or future distribution and focus on limited
navigation within shipping approaches by commercial ships means that
this study may have somewhat limited applicability to how the Navy
trains and tests in SOCAL.
Szesciorka et al. (2019) concluded that while whales have some cues
to avoid ships, this is true only at close range, under certain
oceanographic conditions and if the whale is not otherwise distracted
by feeding, breeding, or other behaviors. The paper is based on a
single blue whale reaction observed in the Santa Barbara Channel, north
of, and outside of, SOCAL. The blue whale was tagged as part of the
U.S. Navy-funded Southern California Behavioral Response Study (SOCAL
BRS) 2010-2015 and exposed to simulated MFAS when a closest point of
approach of 93 m from a passing commercial container ship was noted.
The whale was only tagged for a couple of hours before tag detachment.
As other published papers report from the SOCAL BRS and as cited in the
2018 HSTT FEIS/OEIS, there can be significant individual variation in
response to anthropogenic sources, which in this case would include
vessel transit.
Blondin et al. (2020) estimated blue whale vessel strike risk in
the Southern California Bight by combining predicted daily whale
distributions with continuous vessel movement data for 4 years (2011,
2013, 2015, 2017). The study focuses on the northern Southern
California Bight associated with the commercial vessel traffic
separation zone through Santa Barbara Channel approaching the Port of
Los Angeles/Long Beach. This area is north of and outside of SOCAL. The
authors found that vessel traffic activity across years (2011, 2013,
2015, 2017) was variable and whale spatial probability was also
variable based on inter-annual fluctuations in environmental
conditions. Similar to previous monitoring efforts in Southern
California, blue whales are typically in higher concentrations north of
SOCAL from July-November (Mate et al. 2018), and Blondin et al. (2021)
also picked up on this seasonal variability in their analysis.
Oceanographic conditions favorable for krill development and
concentration (i.e., cool water periods) would lead to increased blue
whale occurrence and higher strike risk as evidenced during the higher
number of blue whale strikes in 2007 (Berman-Kowalewski et al. 2010).
Finally, the coarse level of data analyzed by the authors does not
account for short-term patchy prey conditions influencing blue whale
occurrence and may result in overestimation of average risk.
Redfern et al. (2020) revised their 2019 assessments of vessel
strike risk off California using interannual variability of risk across
multiple years for blue whale, fin whale and humpback whale. The
authors showed higher concentrations of both blue and fin whales along
the Central California coast as compared to within SOCAL. Magnitude of
vessel strike risk was influenced by the ship traffic scenario. In
addition, interannual species variability (1991, 1993, 1996, 2001,
2005, 2008, and 2009) also influenced the magnitude of vessel strike
risk, but did not change whether nearshore or offshore scenarios had
higher risk. The author's conclusions were similar to Redfern et al.
(2019). Figure 2 from Redfern et al. (2020) illustrates mean blue
whale, fin whale, and humpback whale vessel strike risk for California
based on data through 2009. Results from more recent NMFS surveys in
2014 and 2018 may or may not change this assessment in the future.
Rockwood et al. (2020b) calculated expected blue whale and humpback
whale mortality for hypothetical compliance scenarios by imposing speed
caps within and adjacent to vessel traffic lanes leading to the Port of
San Francisco in Central California, 400 miles (643.7 km) north of
SOCAL. Rookwood et al. (2020a) had already demonstrated this area off
Central California had concentrated krill prey with associated higher
distributions of blue whales and humpback whales. Rookwood et al.
(2020b) used better temporal resolution density data than previous
modeling efforts reported by Rookwood et al. (2017). Biological data
analysis for Rookwood et al. (2020b) was based on regional monthly
krill and whale surveys from 2004-2017. Rockwood et al.'s (2020b)
overall modeling conclusions were that lower commercial ship speeds
within the vessel traffic lanes could potentially reduce whale
mortality from vessel strike. The authors acknowledge that local
changes in whale abundance can have strong effects on both inter-annual
and long-term patterns of ship-strike mortality.
Bernknopf et al. (2021) examined the socioeconomic benefits of
using remotely-sensed information instead of in situ observations for
determining blue whale occurrence in the eastern North Pacific Ocean.
Their analysis used blue whale spatial distribution through 1991-2009
projects as representative of 2017 densities (Becker et al. 2012)
combined with automatic identification system (AIS) derived measures of
civilian commercial vessel traffic to predict blue whale vessel strike
risk, called the Reference Case by the authors. The authors then
compared estimated blue whale strike risk in a second analysis that,
instead of using empirically measured blue whale observations converted
into spatial habitat maps, used satellite tracking and environmental
data to identify the spatial and temporal distribution of blue
[[Page 68300]]
whales, called the Counterfactual Case by the authors (Hazen et al.
2017). Estimated mean fatal strikes to blue whales for the Reference
Case based on empirical density data from 1991-2009 ranged from 0.0490
to 2.5877 (max. values >1.000 between June to October) (see Table 2 in
Bernknopf et al. 2021). Estimated mean fatal strikes to blue whales for
the Counterfactual Case based on environmental estimates of blue whale
density in 2017 ranged from 0.0286 to 2.1556 (max. values >1.000
between August to October). An important caveat to this research is
that the two approaches result in different strike risks due to using
different blue whale density estimates.
Barkaszi et al. (2021) designed a model to estimate risks to large
whales from shipping associated with offshore wind development along
the U.S. Atlantic Coast. A key caveat for the model is that it is based
on civilian vessel types associated with wind energy construction
(e.g., tugs, service craft, etc.) with relatively fixed, direct routes
to offshore wind sites. Therefore, while lower vessel speeds can reduce
mortality, prediction and implementation of reduced speed zones are a
far more complex challenge (Barkaszi et al. 2021). Vessel speed has
less effect on strike risk over a fixed distance with fixed target
density when there are no behavioral components considered (Yin et al.
2019). Vessel speed has a significant effect on strike risk only when
behavioral components are considered, thus the ability for the user to
input animal or vessel aversion is an important variable that can
provide insights to the encounter risk based on vessel speeds.
Cusato (2021) discusses the merits of vessel traffic separation
changes or mandatory commercial ship speed reductions in the Santa
Barbara Channel to reduce the risk of vessel strikes to large whales.
The author compares it to similar restrictions on the U.S. East Coast
for North Atlantic right whales. The paper is a policy discussion
rather than an analysis of current biological distribution of large
whales and associated risk. Cusato (2021) focuses on reducing risk from
commercial ships in the current vessel traffic separation scheme within
the Santa Barbara Channel. Speed restrictions in the Channel would need
to be implemented through either Federal regulations or Federal
statute. The author also correctly points out legitimate concerns that
operating large vessels at slow speeds in certain conditions could pose
a safety risk because large vessels are more difficult to control and
steer at slower speeds.
Hausner et al. (2021) examined tradeoffs of blue whale vessel
strikes and speed reduction mitigation over a 17-year period from 2002
to 2018 in the Southern California Bight under two management scenarios
verses a ``fixed strategy'' that implements speed reductions for a
fixed time period each year. The two management strategies were (1) a
``daily strategy'' implementing speed reductions in response to whale
habitat conditions on a daily basis, and (2) a ``seasonal strategy''
implementing speed reductions in response to whale habitat conditions
on a seasonal basis. The period of the author's data analysis also
covers the abnormal marine heat wave along the U.S. West Coast (2014-
2016). The study's focus was exclusively with the traffic separation
lanes leading from the Santa Barbara Channel to the Ports of Los
Angeles and Long Beach, a narrow corridor north of and outside of
SOCAL. The daily and seasonal management strategies were more effective
in reducing blue whale strike risk in the Santa Barbara channel than
the fixed strategy. The daily management strategy had the highest
protective effect. This apparent difference in strategies also applied
during and after the 2014-2016 marine heat wave where the daily
strategy added even extra protection. The authors acknowledged that
interannual variation on blue whale presence in the shipping lanes
added some variability to their analysis. In addition, their study only
considered blue whales sighted within the Traffic Separation Scheme, as
opposed to the broader region where vessels transit through or a blue
whale could occur.
Ransome et al. (2021) documented 40 vessel strikes to large whales
in the Eastern Tropical Pacific Ocean between 1905 and 2017 off the
coasts of 10 Central and South American countries (Mexico to Columbia).
The authors concluded that vessel strikes to large whales are more
prolific in this region than previously reported. For instance, the
author's findings of 40 vessel strikes was over three times greater
than previous reporting and still is likely under reporting total whale
strikes. The majority of whale strikes occurred from the 1950s onward
with the growth of modern shipping and whale watching. Humpback whales
were the most commonly struck species (45 percent) although 30 percent
of the species were not identified in their data.
Rockwood et al. (2021), similar to Rockwood et al. (2020b),
calculated potential whale strike mortalities using AIS vessel data and
whale density data to estimate mortality under several management
scenarios within the commercial shipping lanes passing through Santa
Barbara Channel and San Pedro Channel to and from the Ports of Los
Angeles and Long Beach. While the Santa Barbara Channel is
approximately 100 miles (160.9 km) north of SOCAL, Rockwood et al.'s
study area also included the southern vessel traffic approach to Los
Angeles and Long Beach which did extend into the northeast coastal
portion of SOCAL. Recent whale surveys were not available for this
effort, so the authors used long-term average blue, fin, and humpback
whale densities from Becker et al. (2016). The author's model also
predicted a higher level of whale vessel strikes from commercial ships
than Rockwood et al. (2017), although the authors acknowledged that for
the 2020 publication they included more vessel classes than for the
2017 publication.
Silber et al. (2021) examined the risk to gray whales from
commercial shipping in the North Pacific. Vessel strike risk was
highest for gray whales including the Western North Pacific Distinct
Population Segment (WNP DPS) along most of the migratory routes.
Highest risk to the WNP DPS of gray whales was outside of the SOCAL in
the western Bering Sea, along the east coast of the Kamchatka peninsula
(Russia), and coastlines of Japan. For both Eastern North Pacific and
WNP DPSs of gray whales, the greatest vessel strike risk along the U.S.
West Coast was from Washington to Central California.
Helm et al. (2023) looked at strike risk to foraging humpback
whales surfacing around large cruise ships transiting Glacier Bay
National Park, Alaska. The authors concluded that the probability of
foraging humpback whales remaining near the surface after first
sightings was relatively high. While this puts humpback whales at
increased risk of ship strike, it also allows shipboard observers more
time to spot whales in order to maneuver the ship to avoid a strike.
Lookout Effectiveness
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
[[Page 68301]]
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. 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.
Hearing, Vocalization, and Masking
Branstetter et al. (2021) measured underwater, masked hearing
thresholds for frequencies between 0.5 and 80 kilohertz (kHz) in two
killer whales. Critical ratios computed from the threshold measurements
ranged from 16 to 32 decibels (dB). For communication signals in the
1.5-15 kHz range, killer whales would require the signal to be up to 26
dB above background Gaussian noise to be detected. The authors noted
that ambient background noise in the marine environment is not
Gaussian, the tones used in this study do not contain as much frequency
information as biologically relevant signals, and the temporal and
spectral characteristics of actual signals and noise may result in some
degree of release from masking. These results are consistent with
critical ratio measurements from other odontocete species, despite
differences in hearing ability and head size.
Fournet et al. (2021) measured call amplitudes from male bearded
seals in the Beaufort Sea under different ambient noise conditions. The
results showed that estimated source levels of seal calls increased
with ambient noise up to approximately 100-105 dB root-mean-squared
(rms), above which no further Lombard effect was observed. This
suggests that masking of bearded seal mating calls may occur, resulting
in reduced communication range, which could reduce the ability of
bearded seals to detect one another, mate, and reproduce.
Mercado (2021) aimed to characterize how units within humpback
whale songs were systematically varied using a large dataset of
recordings from off the coast of Kona, Hawaii. The data showed that
narrowband, reverberant units repeated at regular time intervals and
dominated most song sessions, while broadband units were less
predictable and occupied frequency bands that did not overlap with the
narrowband units. The persistent production of narrowband units at
regular time intervals resulted in consistent reverberation, which
could either function to increase the range at which the song can be
detected, or listen for fluctuations in echoes to indicate the presence
of whale-sized targets.
Rey-Baquero et al. (2021) collected theodolite and passive acoustic
data on humpback whales in a pristine environment along the Colombian
Pacific for 2 months. When acoustic data (n=34 files) were analyzed for
unit duration and inter-unit interval before and after boats passed,
song unit lengths were shorter and more variable when boats were
present. The second aim of this study was to model the whales'
communication space during ambient noise or one to two boats traveling
slowly. The most common peak frequency of this stock's song (350 Hz)
was used in the model, and, along with a whale's location along the
coast, informed calculations of transmission loss. However, the source
level of ``typical whale-watching boats'' (145 dB re 1 uPa (decibels
referenced to 1 micropascal) at 1 m; (Erbe et al. 2012)) and humpback
whales (153 dB re 1 uPa at 1 m; (Au et al. 2006)) were taken from
previous studies. Authors found that the infrequent addition of ecotour
boat noise could temporarily reduce the ``very audible area'' (>10 dB
SNR) in their song's commonly used peak frequency (350 Hz) by 63
percent.
Ruscher et al. (2021) measured aerial behavioral hearing thresholds
in a Hawaiian monk seal (Neomonachus schauinslandi). The results showed
a hearing range between 0.1 and 33 kHz with relatively poor sensitivity
compared to Phocinae seals. The most sensitive thresholds were 40 dB re
20 [mu]Pa measured at 800 Hz and 3.2 kHz. The resulting audiogram was
most similar to the northern elephant seal, which is the only other
species of Monachinae seal with audiogram data (Reichmuth et al. 2013).
This study suggested that hearing sensitivity of Monachinae seals is
substantially reduced compared to other species within their functional
hearing group (phocid carnivores in air; PCA); therefore, the use of
the PCA weighting function to predict auditory impacts is likely
conservative for Hawaiian monk seals.
Sills et al. (2021) measured underwater auditory detection
thresholds in a male Hawaiian monk seal, and the range of most
sensitive hearing was between 0.2 and 33 kHz. Peak hearing sensitivity
of 73 dB re 1 [mu]Pa was observed at 1.6 kHz. The audiogram for this
individual was similar but narrower and elevated compared to the
hearing group (phocid carnivores in water; PCW) composite audiogram
used to assess impacts to this species. Underwater vocalizations were
also measured, and 6 call types were identified, which had peak energy
between 55 and 400 Hz. The number of calls produced per minute
fluctuated seasonally and peaked in the breeding season with the
highest call rates recorded in December.
Sweeney et al. (2022) examined the difference between noise impact
analyses using unweighted broadband sound pressure levels (SPLs) and
analyses using auditory weighting functions. The recordings used to
conduct parallel analyses in three marine mammal species groups were
from a shipping route in Canada. Since shipping noise was predominantly
in the low-frequency spectrum, bowhead whales perceived similar
weighted and unweighted SPLs while narwhals and ringed seals
experienced lower SPLs when auditory weighting functions were used. The
data provide a real-world example to support the use of weighting
functions based on hearing sensitivity when estimating audibility and
potential impact of vessel noise on marine mammals.
A study by von Benda-Beckmann et al. (2021) modeled the effect of
pulsed and continuous 1-2 kHz active sonar on sperm whale echolocation
clicks and found that the presence of upper harmonics in the sonar
signal increased masking of clicks produced in the search phase of
foraging compared to buzz clicks produced during prey capture.
Different levels of sonar caused intermittent to continuous masking
(120 to 160 dB re 1 [mu]Pa2, respectively), but varied based on click
level, whale orientation, and prey target strength. CAS resulted in a
greater percentage of
[[Page 68302]]
time that echolocation clicks were masked compared to PAS.
Kastelein et al. (2021c) compared the ability of harbor porpoises
to detect signals in constant-amplitude noise with amplitude-modulated
noise. Underwater, behavioral hearing thresholds were measured from
harbor porpoises at 4 kHz under three conditions: ambient noise
(control), sinusoidally amplitude modulated (SAM) masking noise, and
Gaussian (constant amplitude) masking noise. Both masker types were
centered at 4 kHz with a one-third octave bandwidth and were tested at
various SPLs. The SAM noise was also tested at modulation rates from 1-
90 hertz (Hz). The 4 kHz hearing test signals were 0.5, 1, and 2
seconds in duration. The results showed that, compared to Gaussian
noise, up to 14.5 dB of masking release (from ``dip listening'') was
observed in lower-modulation rate (1-5 Hz) SAM noise. The effect of
masking on communication space is often modeled using constant-
amplitude noise, whereas most Navy sources contain gaps, more like
amplitude-modulated noise. This study suggests that the signal
duration, masker level, and masker modulation rate and depth should be
considered when modeling the effect of noise on signal detection.
Isojunno et al. (2021) used data from 15 tagged sperm whales
(Isojunno et al. 2020) to evaluate odontocete echolocation behavior as
a function of received sonar exposures. Statistical analysis revealed
small reductions in the number of buzzes and movement during sonar, but
the most apparent change in echolocation behavior was a Lombard effect
observed during higher sea states (increased surface noise). No
behavioral changes in orientation relative to the sonar source were
observed that would suggest an anti-masking strategy for spatial
release from masking. Theoretical modeling of masking potential in
terms of detection range revealed that search phase clicks would likely
be masked during both PAS and CAS, but the buzz clicks would not. For
regular search phase clicks to be continuously masked, SELs would have
to be equal to or greater than 160 and 173 dB re 1 [mu]Pa\2\s (dB
referenced to 1 micropascal squared seconds) for PAS and CAS,
respectively. Overall, the data showed more evidence for masking by
increases in ambient noise (surface noise from higher sea states), than
for sonar. This result could be due, in part, to the 1-2 kHz narrowband
sonar masker, which is not comparable to broadband maskers such as
ambient noise or shipping noise.
Matthews and Parks (2021) reviewed the existing literature on North
Atlantic right whale acoustic behavior and summarize information on
acoustic behavior of the Southern right whale, North Pacific right
whale, and bowhead whale. The authors reviewed primary literature on
whale vocalizations, anatomical modeling, and behavioral responses to
playbacks to conclude that the North Atlantic right whale might have a
hearing range of 20 Hz to 22 kHz. However, vocalization data cannot be
used to directly estimate audible range since there are many examples
of mammals (including marine mammals) that vocalize with energy below
the frequency of best hearing, and calls can also contain high-
frequency harmonics that are above the upper limit of hearing. The
anatomical model developed by Ketten (1994) was used by Parks et al.
(2007) to estimate a functional hearing range of 15 Hz to 18 kHz for
this species.
Jacobson et al. (2022) modeled the probability of Blainville's
beaked whale group vocal periods (GVPs) on the Pacific Missile Range
Facility during periods of no naval activity, naval activity without
hull-mounted MFAS, and naval activity with hull-mounted MFAS. Data were
collected from bottom-mounted hydrophones on the range before, during,
and after six Submarine Commanders Course (SCC) exercises. At an MFAS
received level of 150 dB re 1 [mu]Pa rms (root mean square), the
probability of GVP detection decreased by 77 percent (95 percent CI: 67
percent-84 percent) compared to periods when general training activity
was ongoing and by 87 percent (95 percent CI: 81 percent-91 percent)
compared to baseline conditions. This study found a greater reduction
in p(GVP) with MFAS than observed in a prior study of Blainville's
beaked whales at the Atlantic Undersea Test and Evaluation Center
(AUTEC) (Moretti et al. 2014). The authors suggest that this may be due
to the baseline period in the AUTEC study including naval activity
without MFAS, potentially lowering the baseline p(GVP), or due to
differences in the residency of the populations at each range.
Branstetter and Sills (2022) reviewed direct laboratory (i.e.,
psychoacoustic) studies of marine mammal hearing in noise.
Psychoacoustic studies of auditory masking in marine mammals were
described in detail and categorized by the type of signal and masker
(e.g., tone in white noise), and specific conditions under which
masking is reduced (i.e., release from masking). Specifically,
comodulation masking release, or the reduction in masking due to
amplitude or frequency modulation differences between the signal and
noise, and spatial release from masking, or the reduction in masking
due to spatial separation between signal and noise and the directional
hearing ability of the listener, are discussed. Finally, energetic
masking, or the ability of the listener to detect a signal was compared
to informational masking, or the ability of the listener to comprehend
the signal was reviewed. The authors point out that while the body of
scientific evidence thus far shows that processes of the ear result in
energetic masking, more research on informational masking is needed to
develop realistic communication space models. This is because current
communication space models are based on 50 percent signal detection
rather than some threshold of successful signal recognition or
interpretation by the listener.
Hearing Loss (TTS and PTS)
Houser (2021) reviews existing literature on the relationship
between auditory threshold shift and tissue destruction in mammals.
According to small terrestrial mammal literature, TTSs of approximately
30-50 dB measured 24 hours after sound exposure induced progressive
tissue damage despite the return of normal hearing thresholds. Although
large TTSs allow for full recovery of hearing, pathological tissue
destruction may occur; however, smaller-magnitude TTSs are unlikely to
result in tissue damage. The author concludes that the current criteria
of 40 dB of TTS measured within minutes of the noise exposure as the
onset of injury is likely to encompass recoverable auditory threshold
shift without tissue damage. This publication supports the use of
current definitions of auditory injury in marine mammals.
Kastelein et al. (2022a) measured underwater behavioral hearing
thresholds in two California sea lions at 0.6, 0.85, and 1.2 kHz before
and after exposure to a one-sixth-octave noise band centered at 0.6 kHz
for 60-minutes. Hearing tests were also conducted at 1, 1.4, and 2 kHz
after exposure to a one-sixth-octave noise band centered at 1 kHz for
60-minutes. For the 0.6 kHz exposure, the maximum TTS was 7.5 dB (6.7
dB mean) for a 210 dB cumulative SEL (SEL<INF>cum</INF>) exposure at
the hearing test frequency one-half octave above the center frequency
of the fatiguing stimulus (0.85 kHz), which recovered after
approximately 12 minutes. For the 1 kHz exposure, the maximum TTS was
10.6 dB (9.6 dB mean) after a 195 dB SEL<INF>cum</INF> exposure at the
hearing test frequency one-half octave above the center frequency of
the fatiguing
[[Page 68303]]
stimulus (1.4 kHz). Mean threshold shift (TS) greater than 6 dB (mean =
8.0 dB, min = 7.2 dB, max = 8.5 dB) was also observed after exposure to
the 1 kHz fatiguing stimulus at 195 dB SEL<INF>cum</INF> for the 1 kHz
hearing test frequency. For this exposure frequency, hearing recovered
within 24 minutes. The results of this study show individuals
exhibiting onset of TTS in water at lower received levels than the
otariid thresholds in ``Criteria and Thresholds for U.S. Navy Acoustic
and Explosive Effects Analysis (Phase III)'' (Navy, 2017).
Kastelein et al. (2022b) measured underwater behavioral hearing
thresholds in two California sea lions at 8, 11.3, and 16kHz before and
after exposure to a one-sixth-octave noise band centered at 8 kHz for
60-minutes. Hearing tests were also conducted at 32 kHz after exposure
to a one-sixth-octave noise band centered at 16 kHz for 60-minutes. For
the 8kHz exposure, the maximum TTS was 20.2 dB (18 dB mean) for a 190
dB SEL<INF>cum</INF> exposure at the hearing test frequency one-half
octave above the center frequency of the fatiguing stimulus (11.3 kHz),
which recovered after approximately 12 minutes. For the 16 kHz
exposure, the maximum TTS was 19.7 dB (16.3 dB mean) after a 207 dB
SEL<INF>cum</INF> exposure at the hearing test frequency one-half
octave above the center frequency of the fatiguing stimulus (22.4 kHz).
For these exposure frequencies and scenarios, hearing recovered within
72 minutes or less. The results of this study show TTS onset in-water
occurred at lower received levels than what the current otariid
criteria in ``Criteria and Thresholds for U.S. Navy Acoustic and
Explosive Effects Analysis (Phase III'') (Navy, 2017) suggest.
Kastelein et al. (2021a) measured underwater behavioral hearing
thresholds at 0.5, 0.71, and 1 kHz in one harbor porpoise before and
after exposure to one-sixth-octave band noise centered at 0.5 kHz.
Maximum TTS was 8.9 dB (mean = 7.6 dB) at the 0.5 kHz hearing test
frequency after a 205-dB SEL<INF>cum</INF> exposure. For the 0.71 and 1
kHz hearing test frequencies, no mean TTS > 6 dB was observed. However,
at 0.71 kHz, maximum TTS was 6.5 dB (mean = 5.8 dB) was observed after
a 205-dB SEL<INF>cum</INF> exposure. At 1 kHz, a maximum of 6.3 dB of
TTS (mean = 5.7 dB) occurred after 206-dB SEL<INF>cum</INF> exposures.
All shifts < 5 dB recovered within 12 minutes and shifts > 6 dB
recovered within 60 minutes. These results are consistent with the
criteria and thresholds described in ``Criteria and Thresholds for U.S.
Navy Acoustic and Explosive Effects Analysis (Phase III)'' (Navy,
2017).
Kastelein et al. (2021b) measured behavioral, underwater hearing
thresholds at 2, 2.8, and 4.2 kHz in two sea lions before and after
exposure to band-limited noise centered at 2 kHz. Sea lion hearing was
also tested at 4.2, 5.6, 8 kHz before and after exposure to noise
centered at 4 kHz. Maximum TTS was 24.1 dB (22.4 dB mean) at the 5.6
kHz test frequency after a 205-dB SEL<INF>cum</INF> exposure centered
at 4 kHz. Threshold shifts greater than or equal to 6 dB occurred at
187, 181, and 187 dB SEL<INF>cum</INF> for 4.2, 5.6, and 8 kHz test
frequencies respectively. After exposure to the 2-kHz noise, maximum
TTS of 11.1 dB (10.5 dB mean) occurred for 203 dB SEL<INF>cum</INF> at
the 2 kHz test frequency. Threshold shifts greater than or equal to 6
dB occurred at SEL<INF>cum</INF> of 192, 186, and 198 dB for test
frequencies 2, 2.8, and 4.2 kHz respectively. These data suggest that
one-half octave above the exposure frequency is the most sensitive to
noise exposure. TTS between 6 and 10 dB recovered within 60 minutes,
10-15 dB of TTS recovered within 120 min, and TTS up to 24.1 dB
recovered after 240 minutes. The results of this study show individuals
exhibiting onset of TTS in-water at lower received levels than the
current otariid criteria (``Criteria and Thresholds for U.S. Navy
Acoustic and Explosive Effects Analysis (Phase III)'' (Navy, 2017)).
Kastelein et al. (2020a) measured underwater, behavioral hearing
thresholds in one harbor porpoise before and after exposure to
playbacks of one-sixth-octave band noise centered at 1.5 kHz and a 6.5
kHz continuous wave. Following exposure to the 1.5 kHz noise band at
201 dB SEL<INF>cum,</INF> a maximum of a 7.8 dB, 9.8 dB, and 7 dB TTS
was observed for 1.5, 2.1, and 3 kHz hearing frequencies respectively.
After exposure to the 6.5 kHz continuous wave at 184 dB
SEL<INF>cum</INF>, a maximum of a 7.5, 16.7, and 11.8 dB TTS was
observed for 6.5, 9.2, and 13 kHz hearing frequencies respectively. For
the 6.5 kHz exposure, a mean TTS > 6 dB was observed for the 178 and
180 dB SEL<INF>cum</INF> when the hearing test frequency was 9.2 kHz,
and for the 180 dB SEL<INF>cum</INF> when the hearing test frequency
was 13 kHz. The results of this study show that the animal incurred
onset of TTS at higher received levels than what the current HF
cetacean criteria in ``Criteria and Thresholds for U.S. Navy Acoustic
and Explosive Effects Analysis (Phase III)'' (Navy, 2017) indicate for
both 1.5 and 6.5 kHz.
Kastelein et al. (2020b) measured underwater, behavioral hearing
thresholds in two harbor seals before and after exposure to playbacks
of one-sixth-octave band noise centered at 0.5, 1, and 2 kHz. Hearing
tests were conducted at the center frequency, one-half octave above,
and 1 octave above center frequency. No TTS > 6 dB was observed for any
hearing frequency after 204, 210, or 211 dB SEL<INF>cum</INF> exposures
to the 0.5 kHz noise band. For the 1 kHz exposure frequency, max TTS of
7.4 dB (6.1 mean) was observed after a 207 dB SEL<INF>cum</INF>
exposure at a hearing frequency of 1.4 kHz. For this exposure
frequency, no other test condition produced TTS > 6 dB; although, a 5.9
dB shift (at 1.4 kHz) occurred at 206 dB SEL<INF>cum.</INF> For the 2
kHz noise band, after a 201 dB SEL<INF>cum</INF> exposure, max TTS of
12 dB was measured one octave above the center frequency (4 kHz). For
this exposure frequency, TTS > 6 dB was observed at SEL<INF>cum</INF> >
201, 198, and 192 dB for hearing frequencies 2, 2.8, and 4 kHz
respectively. All shifts recovered within 1 hour. These results of this
study show that the animal incurred lower TTS (i.e., smaller threshold
shifts) at higher received levels than what the current phocid pinniped
criteria in ``Criteria and Thresholds for U.S. Navy Acoustic and
Explosive Effects Analysis (Phase III)'' (Navy, 2017) indicate.
Kastelein et al. (2020c) measured underwater, behavioral hearing
thresholds in one harbor porpoise before and after exposure to
playbacks of one-sixth-octave band noise centered at 88.4 kHz. Maximum
TTS of 13.6 dB was observed at 197 dB SEL<INF>cum</INF> for the 100 kHz
hearing test frequency. No TTS > 6 dB was observed for any
SEL<INF>cum</INF> at the 88.4 kHz test frequency. For 125 kHz, shifts >
6 dB were observed for 191, 194, and 197 dB SEL<INF>cum</INF>
exposures, with a mean TTS of 5.4, 6.1, and 5.9 dB, respectively. The
results of this study show that the animal incurred TTS at higher
received levels than what the current HF cetacean criteria in
``Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects
Analysis (Phase III)'' (Navy, 2017) suggest.
Kastelein et al. (2020d) measured underwater, behavioral hearing
thresholds in one harbor porpoise before and after exposure to airgun
impulses (``shots''). Exposure conditions varied with regard to number
of airguns, number of shots, light cues, and position of the dolphin
relative to the airguns. Hearing test frequencies were 2, 4, and 8 kHz,
and no TTS > 6 dB was observed. The results of this study show that the
animal would incur TTS onset at higher received levels than what the
current HF cetacean criteria in ``Criteria and Thresholds for U.S. Navy
Acoustic and Explosive Effects Analysis (Phase III)'' (Navy, 2017)
suggest.
[[Page 68304]]
Kastelein et al. (2020e) measured underwater, behavioral hearing
thresholds in two harbor seals before and after exposure to playbacks
of one-sixth-octave band noise centered at 40 kHz. For the 50 kHz
hearing test frequency, a maximum TTS of 30.7 dB was observed 12-16
minutes after the 189 dB SEL<INF>cum,</INF> and a mean TTS > 6 dB was
observed for all SEL<INF>cum</INF> 177 dB and above. The 30-dB shift
recovered after 3 days. No TTS > 6 dB was observed for any
SEL<INF>cum</INF> at the 63 kHz test frequency for either seal. At 40
kHz, mean TTS of 9.2 dB was observed after a 189-dB SEL. The results of
this study show that the animal incurred TTS at lower received levels
than what the current phocid criteria in ``Criteria and Thresholds for
U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)'' (Navy,
2017) suggest.
Sills et al. (2020) exposed one bearded seal to multiple impulsive
underwater noise exposures (seismic air gun ``shots''). Hearing tests
were conducted at 100 Hz and 400 Hz after exposures to 2, 4, and 10
shots. After a 4-shot (191 dB SEL<INF>cum</INF>) exposure, max TTS of
9.4 dB was observed, but no other TTS > 6 dB was demonstrated, despite
four 10-shot (194-195 dB SEL<INF>cum</INF>) exposures. It is possible
that TTS recovered during the measurements, as quantified by a mean
``first miss'' of 7.5 dB for the 10-shot exposures (mean TTS was 2.2
dB). The results of this study show that the animal incurred TTS onset
at lower received levels than what the current criteria in ``Criteria
and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis
(Phase III)'' (Navy, 2017) suggest. Behavioral responses were also
scored and averaged across three observers. For most exposures, the
seal exhibited mild/detectable responses, and all scores indicated that
the seal did not move more than half his body and consistently
participated in the study.
Tougaard et al. (2022) reviewed the most recent temporary TTS data
from phocid seals and harbor porpoises and compared empirical data to
the predictive exposure functions put forth by Southall et al. (2019),
which were based on data collected prior to 2015. The authors concluded
that more recent data supports the thresholds used for harbor porpoises
(categorized as `very high frequency', or VHF cetaceans), which over-
estimated the hearing impact for sounds above 20 kHz in frequency.
Similarly, the new data for phocid seals show TTS onset thresholds that
are well-above the predicted levels for sounds below 5 kHz in
frequency. However, phocid seals might be more sensitive to higher
frequency sound exposures than predicted, as the TTS onset data for
frequencies higher than 20 kHz was below the predicted levels.
von Benda-Beckmann et al. (2022) assessed whether correcting for
kurtosis, a measure of sound impulsiveness, improved the ability to
predict TTS in a marine mammal. Two different kurtosis correction
factors were tested by applying them to frequency-weighted sound
exposure levels (SEL<INF>cum</INF>) and fitting (linear least squares)
previously collected harbor porpoise TTS data to create dose-response
functions, then comparing the resulting R\2\ values to that of the
standard function used to fit TTS growth data. TTS data from both
continuous and intermittent sound exposures were used. For intermittent
and continuous 1-2 kHz exposures combined, kurtosis-corrected fits were
poorer (R\2\ = 0.47, 0.68) than SEL<INF>cum</INF>-based fits (R\2\ =
0.73). For intermittent exposures of different types, one of the
kurtosis-corrections resulted in a better fit (R\2\ = 0.84) than
SEL<INF>cum</INF> (R\2\ = 0.64), but only when a model fitting
parameter denoting the relationship between SEL<INF>cum</INF> and risk
of permanent hearing loss was specifically derived from harbor porpoise
TTS growth data. The conclusions from this study were that the
kurtosis-corrected SELs did not explain differences in TTS between
intermittent and continuous sound exposures, likely because silent
intervals provided an opportunity for hearing recovery that could not
be accounted for by these models. Kurtosis might still be useful for
evaluating sound exposure criteria for different types of sounds having
various degrees of impulsiveness.
Behavioral Reactions
In a study by Benti et al. (2021), vocalizations from Northeast
Atlantic herring-feeding killer whales and Northeast Pacific mammal-
eating killer whales were played back to humpback whales in Norwegian
waters while their behavior was monitored through animal-borne tags and
visual observations. In five of six cases the humpback whales
approached the fish-eating killer whales, suggesting some attraction.
The response to the mammal-eating killer whales varied with the
behavioral context of the humpback whales. The results suggested that
the calls of the fish-eating killer whales may have acted like a
dinner-bell and initiated approach and foraging behavior in the
humpback whales, while the unfamiliar sounds of the mammal-eating
killer whales may have been perceived as a threat in offshore waters,
but led to mixed behavior during inshore herring foraging by humpback
whales. These results indicated that the humpback whales were able to
discriminate between the different call types and respond with
different behavioral strategies.
Boisseau et al. (2021) exposed foraging minke whales in Icelandic
waters to an acoustic deterrent device that emitted 15 kHz pure tones
with a source level of 198 dB rms. Pulse length and the number of
pulses in a block were randomized but average pulse length was 752
millisecond (ms) with a 10 percent duty cycle. The source was deployed
from a Zodiac boat 500 m away from an animal for the first two
exposures, and 1000 m away in the remaining 8 exposures (max received
level of 150 dB RMS at a minimum distance of 338 m). Video-range
tracking was used to track animals before, during, and after the
exposures and dive duration (sec), swim speed (km/h), reoxygenation
rate (blows/min), and path predictability were also examined. During
the exposure, animal speed and dive duration increased, measures of
path predictability increased indicating straighter paths, and
reoxygenation rate decreased. Path predictability had a strong
relationship with received level whereas speed and dive duration did
not, which suggested those two metrics were more influenced by the
presence of the exposure signal than the received sound level.
Cur[eacute] et al. (2021) conducted controlled exposure experiments
using both PAS (5 percent duty cycle) and CAS (95 percent duty cycle)
to measure and score tagged sperm whale behavioral responses. No sonar
control exposures resulted in significantly fewer and less severe
behavioral responses than sonar exposures. No significant differences
were observed between sonar types, but the presence of killer whales or
pilot whales did significantly increase the number of responses. The
probability of observing low and medium severity responses increased
with cumulative sound exposure level (SEL, dB re 1 [mu]Pa2 s), reaching
a probability of 0.5 at approximately 173 dB SEL for low severity
responses. Medium severity responses reached a probability of
approximately 0.35 at cumulative SELs between 179 and 189 dB. This
study suggested that both PAS and CAS exposure resulted in a greater
number of behavioral changes in sperm whales as compared to the vessel
(control) alone, and the types of behavioral responses might differ
across sonar types.
Czapanskiy et al. (2021) modeled energetic costs associated with
behavioral response to MFAS using
[[Page 68305]]
datasets from 11 cetaceans' feeding rates, prey characteristics,
avoidance behavior, and metabolic rates. Authors found that the short-
term energetic cost was influenced more by lost foraging opportunities
than increased locomotor effort during avoidance. Additionally, the
model found that mysticetes incurred more energetic cost than
odontocetes, even during mild behavioral responses to sonar.
Durbach et al. (2021) analyzed acoustic tracks from minke whales
detected on the Pacific Missile Range Facility (PMRF) in Hawaii in 3
years before, during, and after major Navy training exercises. These
tracks were fit using a continuous-time correlated random walk at 5-
minute interpolated locations. During sonar periods, fast movement
became more northerly and more directed (less turning), with less
movement south and east in the direction of the training activity, and
this more northerly movement continued after sonar cessation.
Specifically, whales to the north of the training activity were more
likely to head north, while whales that were west of the activity were
more likely to head west. Headings did not appear to change for slow,
undirected movement during sonar. In addition, fast movement was more
likely to occur during sonar than during any other period (70 percent
during vs 35-41 percent in the other periods). Finally, whales were
more likely to stop calling when in the fast state although not
necessarily more during sonar than in other periods; in contrast, slow
moving whales were more likely to stop calling during sonar than other
periods. These results demonstrated that minke whales moved faster and
movements were more directed during periods of active sonar. Minke
whales also avoided the locations of the ships producing the sonar and
were more likely to cease calling during sonar.
Fernandez-Betelu et al. (2021) used passive acoustic data recorded
over a 10-year time period to assess the effects of impulsive noise
produced during offshore activities on coastal bottlenose dolphin
occurrence. Offshore activities included seismic surveys and pile
driving from wind farm construction. Echolocation detections of
dolphins were compared across years with and without offshore activity
and also across days with and without impulsive noise. The effect of
distance from the noise-producing activities on dolphin detections was
also investigated by placing recorders (CPODs) at locations expected to
be the most (impact areas) and least (reference areas) impacted by
noise. No consistent relationship was found between annual dolphin
occurrence and impulsive noise, but significantly more detections were
observed on days with impulsive noise. The results showed that dolphins
were not displaced by impulsive noise levels up to 141 dB re 1 [mu]Pa
and as close as 20 km (10.8 nmi) from the impact area. These results
suggest that the increase in dolphin detections during far-field noise
was likely due to an increase in the number and/or amplitude of
echolocation vocalizations.
Hastie et al. (2021) studied how the number and severity of
avoidance events may be an outcome of marine mammal cognition and risk
assessment. Five captive grey seals were given the option to forage in
a high- or low-density prey patch while continuously exposed to
silence, pile driving, or tidal turbine playbacks (source levels = 148
dB re 1 [mu]Pa at 1 m) for 1 hour. One prey patch was closer to the
speaker, so had a higher received level in experimental exposures.
Overall, seals avoided both anthropogenic noise playback conditions
with higher received levels when the prey density was limited but would
forage successfully and for as long as control conditions when the prey
density was higher, demonstrating a classic cognitive approach utilized
with predation risk and profit balancing.
In a study by Holt et al. (2021a), DTAGs (miniature sound and
movement recording tags) were attached with suction cups to Southern
Resident Killer Whales in the Salish Sea to investigate the
relationship between probability of prey capture and vessel and sound
variables. The predicted probability of prey capture was lower when
vessels increased their speed. Received noise level did not
significantly affect the probability of prey capture. The rate of
descent during dives was slower when echosounders were on. The observed
effects of echosounders suggest that whales prolonged their foraging
efforts to successfully hunt, which could be caused by acoustic masking
or increased attention to vessels. The rate of descent increased with
increasing broadband noise levels and decreasing vessel distance.
Decrease prey abundance also decreased the probability of predicted
prey capture.
Holt et al. (2021b) attached DTAGs to 23 Southern Resident Killer
Whales in the San Juan Islands over 3 field seasons in order to
investigate the effects of vessel distance on underwater foraging
behavior. When vessels were less than 366 m away, whales (n=13)
decreased the number of dives associated with prey capture and the
amount of time spent in these dives. Additionally, female killer whales
were more likely to stop foraging, socializing, and prey-sharing and
instead start traveling when vessels approached at this distance. At
the same distance from vessels, male orcas were more likely to
transition from close prey capture to socializing and prey-sharing, but
would not stop general foraging behavior, such as searching for prey at
deeper depths. Female orcas may therefore be at greater risk than males
during close vessel interactions.
Kates Varghese et al. (2021) analyzed the effect of two separate
surveys using a 12 kHz multibeam echosounder (i.e., downward directed,
unlike ASW sonar) over the Southern California Antisubmarine Warfare
Range (SOAR) hydrophone array on Cuvier's beaked whale foraging. The
authors conducted a spatial analysis, building off a temporal analysis
of a previously presented dataset (Varghese et al. 2020). There were
differences in spatial use of the SOAR for foraging between the 2
survey years. While no change in overall foraging effort was detected
before, during, and after the surveys each year, some localized spatial
shifts in foraging hot spots were detected during and after the survey
in the second year. Because of the known heterogeneity of prey patches
on SOAR, lack of evidence of avoidance of the sound source, and no
observed change in overall foraging effort, the authors suggest that
the observed spatial shifts were most likely due to prey dynamics.
K[ouml]nigson et al. (2021) tested the efficacy of Banana Pingers
(300 ms, 59-130 kHz frequency modulated, 133-139 dB rms re 1 [micro]Pa
at 1 m source level) as a deterrent for harbor porpoise in Sweden. As
described previously, these pingers were designed to avoid potential
pinniped responses. Authors used recorded echolocation clicks with C-
PODs to measure the presence or absence of porpoise in the area.
Porpoise were less likely to be detected at 0 m and within 100 m of an
active pinger, but a pinger at 400 m appeared to have no effect.
In a study by Laborie et al. (2021), unmanned aerial vehicles
(UAVs) were flown at three altitudes (25, 20, and 15 m) over Weddell
seals, including adult males and females and females with pups. There
was generally little response; 88 percent of the time the animals
showed mild vigilance or no responses, and mothers rarely ended
nursing. Agitation or escape responses only occurred in 12 percent of
observations. The strongest response was in females with pups when wind
speeds were lowest and therefore ambient noise levels were at their
lowest. The probability of response
[[Page 68306]]
increased with lower altitude flights, so at altitudes over 25 m a low
level of impact to Weddell seal behavior would be expected.
Manzano-Roth et al. (2022) found that cross seamount beaked whales
reduced clusters of foraging pulses (Group Vocal Periods) during
Submarine Command Course events and remained low for a minimum of 3
days after the MFA sonar activity.
An analysis subsequent to Varghese et al. (2020) suggested that the
observed spatial shifts of Cuvier's beaked whales during multibeam
echosounder activity on the Southern California Antisubmarine Warfare
Range were most likely due to prey dynamics (Kates Varghese et al.
2021).
Ramesh et al. (2021) explored environmental drivers and the impact
of shipping noise on fin whale vocalizations in Ireland. Approximately
3 months of passive acoustic fin whale call data from spring 2016 used
in the habitat model found that fin whale calls increased at night,
along with signs of higher prey availability. Fin whale calls were also
less likely to be detected for every 1 dB re 1 [mu]Pa/minute increase
in shipping noise levels (rms). However, these results should be used
cautiously since the model was more likely to predict the absence of
fin whale detections, rather than their presence.
Santos-Carvallo et al. (2021) monitored fin whale behavior before,
during, and after the presence of whale watching vessels in Caleta
Cha[ntilde]aral de Aceituno to determine if the whale watching activity
was having any adverse impacts on the fin whales. Whale watching
activities were only conducted by local artisanal fishers; 39 boats
have permission but less than 20 conduct the whale watching activity.
Land-based observations were conducted in January and February of 2015-
2018 via binocular scans and focal follow tracking using a theodolite.
Groups of whales were tracked through the area with continuous sampling
of position, behavior, and presence of boats for every surfacing until
they were no longer visible. Behavior was classified as traveling or
resting, and the groups' swim speed, reorientation, and directness
index, and these were modeled relative to the number of boats and
whether the time period was before, during, or after the boats were
present. Most observations occurred within the presence of at least one
boat, but no more than three boats at one time. Travel swim speeds
increased in the after period, while reorientation increased and
directness decreased during and after the presence of boats. During
rest behavior, reorientation increased during the presence of boats
compared to before the boats were present, and directness decreased
during the presence of boats. These results indicate that when whale
watching vessels were present, the fin whales changed their direction
of movement more frequently, with less linear movement than occurred
before the boats arrived; this behavior may represent evasion or
avoidance of the boats. The increase in travel swim speeds after the
boats left the area may be related to the vessel's rapid speeds when
leaving, sometimes in front of animals, leading to more avoidance
behavior after the boats departed.
Arranz et al. (2021) conducted a noise exposure experiment which
compared behavioral reactions of resting short-finned pilot whale
mother-calf pairs during controlled approaches by a tour boat with two
electric (136-140 dB) or petrol engines (139-150 dB). Approach speed
(<4 kn (7.4 km per hour)), distance of passes (60 m (65.6 yd)), and
vessel features other than engine noise remained the same between the
two experimental conditions. Behavioral data was collected via unmanned
aerial vehicle (UAV) and activity budgets were calculated from
continuous focal follows. Mother pilot whales rested less, and calves
nursed less, in response to both types of boat engines compared to
control conditions (vessel >300 m (328 yd), stationary in neutral).
However, they found no significant impact on whale behaviors when the
boat approached with the quieter electric engine, while resting
behavior decreased 29 percent and nursing decreased 81 percent when the
louder petrol engine was installed in the same vessel.
Hiley et al. (2021) exposed groups of harbor porpoises to ``startle
sounds'', which were 200-ms in duration and were band limited (5.5-20.5
kHz) with a peak frequency of 10.5 kHz and a source level of 176 dB re
1 [micro]Pa. There were 13 exposure sequences in which the startle
sound was repeated for 15 minutes at a 0.6 percent duty cycle, and 11
control sequences in which vessels operated but no startle sounds were
played. Despite a larger distance between porpoise groups and vessels
during sound exposure trials (152 m) as compared to control trials (90
m), avoidance responses during exposures were significant whereas no
avoidance was observed for controls. Porpoises avoided the area where
sound exposures took place for approximately 30-60 minutes, and no
long-term exclusion effect was observed.
Pellegrini et al. (2021) examined how boat presence impacts a
unique subspecies of bottlenose dolphin (Tursiops truncatus gephyreus,
Lahille's bottlenose) that vocalizes while foraging cooperatively with
local fishermen who cast nets onto dolphin-herded fish while standing
in coastal waters in Brazil. Dolphin vocalizations changed in response
to the number, type, and speed of boats within 250 m. When more than
one boat was present, dolphins produced fewer whistles and had a lower
click rate and a longer whistle duration; initial and maximum frequency
increased as well, especially when group size or calf presence
increased. Whistles were longer duration when boat speed increased as
well.
Martin et al. (2022) exposed a wild Cape fur seal breeding colony
in Africa to playback recordings of boat noise and sea-side car
traffic. Focal groups of at least six seals were approached by an
experimenter who crawled within 6 m to avoid disturbing the seals.
Seals were exposed to low (60-64 dB re 20 [micro]Pa rms SPL, broadcast
at 6 m), medium (64-70 dB, broadcast at 3 m), or high (70-80 dB,
broadcast at 1 m) levels, depending on the individual's distance to the
speaker. No behavioral differences were found between low, medium, and
high-level groups. Video recorded behavioral analysis demonstrated that
mother-pup pairs spent less time nursing (15-31 percent) and more time
awake (13-26 percent), vigilant (7-31 percent), and mobile (2-4
percent) during boat noise conditions compared to control conditions.
Mothers were more vigilant (26 percent) than pups (7 percent) to medium
levels of boat noise.
Jones[hyphen]Todd et al. (2021) analyzed the movement of seven
Blainville's beaked whales tagged at (AUTEC) relative to MFAS use
during the SCC training event. Data from these tags was previously
reported by Joyce et al. (2019). A continuous time correlated random
walk movement model accounted for location accuracy by modeling 100
track imputations for each tag and arranged samples in equal time
intervals. The probability of whale presence within the boundary of the
instrumented range (on range), and outside the boundary of the
instrumented range (off range) was modeled relative to the time since
the last MFAS transmission. Results show there was a higher probability
that whales on the range would go off range when there were MFAS
transmissions, and that whales off the range would stay off the range
when there were MFAS transmissions. These results indicate a response
to MFAS that lasted for 3 days since transition rates on-off and off-on
the range returned to baseline levels
[[Page 68307]]
after that amount of time. There was also variability in transition
rates and time spent on/off range between individuals, which highlights
the need to analyze a larger sample size of whales.
Durban et al. (2022) tested new methods of observing behavioral
responses of groups of small delphinids to sonar, where the use of tags
is challenging, and the response of the group is more salient than that
of the individual. They tested the use of a land-based observation
platform coupled with a drone and multiple acoustic recorders to
observe the vocal behavior, group cohesion, group size, and group
behavior before, during, and after a simulated sonar exposure. In a
group of short-beaked common dolphins, the authors found the number of
whistles and sub-groups to increase during the exposure period, but the
directivity of the tracked subgroup did not change much.
K[ouml]nigson et al. (2022) tested the efficacy of Banana Pingers
(300 ms, 59-130 kHz frequency modulated, 133-139 dB<INF>rms</INF> re 1
[micro]Pa at 1 m source level) as a deterrent for harbor porpoise in
Sweden. As described previously, these pingers were designed to avoid
potential pinniped responses. Authors used recorded echolocation clicks
with C-PODs to measure the presence or absence of porpoise in the area.
Porpoise were less likely to be detected at 0 m and within 100 m of an
active pinger, but a pinger 400 m appeared to have no effect.
Miller et al. (2022) investigated the risk disturbance hypothesis
that an animal's response decision is a trade-off between perceived
risk and the cost of a missed opportunity (the reward of foraging). The
authors predicted that species that are more vulnerable to predation
would be more likely to respond to both predator sounds and
anthropogenic stressors. Using data collected from 2008 to 2017 during
the 3S project in Norway, changes in foraging duration during killer
whale playbacks and changes in foraging duration during mid-frequency
sonar were positively correlated across the four species examined
(listed in order of increasing sensitivity to foraging disruption:
sperm whales, long-finned pilot whales, humpback whales, and northern
bottlenose whales). This suggests that tolerance of predation risk may
play a role in sensitivity to sonar disturbance.
Paitach et al. (2022) tested the efficacy of Banana Pingers (300
ms, 50-120 kHz frequency modulated, 145 dB +/- 3 dB at 1 m source
level) as a deterrent and entanglement mitigation for Franciscana
dolphins in Brazil. These pingers were designed to emit sound outside
of the best hearing range for pinnipeds and were therefore less likely
to incite a ``dinner bell'' effect. Authors used recorded echolocation
clicks with C-PODs to measure the presence or absence of dolphins in
the area. Dolphins were 19 percent and 15 percent less likely to be
detected nearby and within 100 m of an active pinger respectively, but
dolphins 400 m from the pinger did not appear to avoid it. While a
reduction in vocalizations does not always equate to a reduction in
presence, this species has been previously seen departing from areas
with active pingers. Authors did not witness any habituation to the
pinger during the length of the experiment (64 days), and although they
recorded fewer dolphins in the area over time, they believe this was
due to seasonality rather than habitat displacement.
Siegal et al. (2022) used Dtag data from 15 northern bottlenose
whales tagged during 3S efforts off Norway (2013-2016) to estimate body
density (to represent body condition by lipid energy stores) using
hydrodynamic models and obtain foraging and anti-predator indicators
based on vocal behavior and dive metrics. The authors compared relative
anti-predator/foraging indices to body condition and found that
relative anti-predator to foraging indices typically did not depend on
body condition. This finding is inconsistent with the needs/assets
hypothesis; an individual in poor condition would accept more risk
(i.e., engage in less anti-predator behavior) for foraging
opportunities, whereas healthy animals can afford to be more risk
averse (i.e., have a relatively higher anti-predator to foraging index
ratio). The authors suggest that this result may be due to an
insufficient range of body conditions in the data set to determine a
relationship, or a selection of bolder individuals in the tagging
effort. The authors also suggest that animals in good condition may
take greater predation risks because they may successfully flee. Three
of the 15 whales were exposed to sonar (presented in prior 3S
publications). The authors compared foraging and anti-predator metrics
pre- and post-exposure, showing that all three animals increased their
anti-predator index and reduced their foraging index.
Stanistreet et al. (2022) used passive acoustic recordings during a
multinational navy activity to assess marine mammal acoustic presence
and behavioral response to especially long bouts of sonar lasting up to
13 consecutive hours, occurring repeatedly over 8 days (median and
maximum SPL = 120 dB and 164 dB). Cuvier's beaked whales and sperm
whales substantially reduced how often they produced clicks during
sonar, indicating a decrease or cessation in foraging behavior. Few
previous studies have shown sustained changes in foraging or
displacement of sperm whales, but there was an absence of sperm whale
clicks for 6 consecutive days of sonar activity. Sperm whales returned
to baseline levels of clicks within days after the activity, but beaked
whale detection rates remained low even 7 days after the exercise. In
addition, there were no detections from a Mesoplodon beaked whale
species within the area during and at least 7 days after the sonar
activity. Clicks from northern bottlenose whales and Sowerby's beaked
whales were also detected but were not frequent enough at the recording
site used to compare clicks between baseline and sonar conditions.
Benhemma-Le Gall et al. (2021) compared harbor porpoise presence
and foraging activity between periods of baseline and construction at
two Scottish offshore windfarms with arrays of echolocation click
detectors (C-PODs). Noise levels were measured with calibrated noise
recorders, and vessel presence was tracked with AIS data. Authors found
an 8-17 percent decline in porpoise presence compared to baseline, with
more porpoises (more buzzing) further from vessels, construction sites,
and related higher levels of noise. The probability of porpoise
occurrence by source vessels decreased by 9-23 percent without piling
activity, and by 40-54 percent during pile driving. Porpoises were
displaced up to 12 km (6.5 nmi) from pile driving and 4 km (2.2 nmi)
from construction vessels. At an average vessel distance of 2 km (1.1
nmi), porpoise occurrence decreased by up to 35 percent. Outside piling
hours, porpoise detection decreased by 17 percent (0.26), and foraging
(buzzes) decreased by up to 41.5 percent (0.03) with increasing noise
levels (159 and 155 dB re 1 [micro]Pa, respectively). During piling
activities, porpoise occurrence began lower (0.16, 102 dB) but
occurrence still decreased by 9 percent (0.07), and foraging (buzzes,
beginning at 0.76, 104 dB) also decreased by 61.8 percent (0.15) with
increasing noise levels (161 and 155 dB re 1 [micro]Pa, respectively).
Kastelein et al. (2022c) recorded pile driving sounds 100 m from
construction for an offshore windfarm turbine, and six versions of the
sound were created with varying frequency content using low-pass
filters at 44.1, 6.3, 3.2, 1.5, 1.0,
[[Page 68308]]
and 0.5 kHz, at levels of 135 dB re 1 [micro]Pa\2\s. When authors
played these impulsive sounds back to a single harbor porpoise in a
pool, she increased swim speed, respiration rate, distance from the
transducer, and occasionally jumped in response to the sounds with
higher frequencies present (i.e., the sounds with a wider bandwidth,
especially sounds low-pass filtered at 44.1 and 6.3 kHz). However, the
porpoise still moved away from the three most narrowband sounds, just
not as far. Results indicate that frequency weighting of SEL may
improve prediction of harbor porpoise behavioral responses, and authors
present the argument that weighted SELs should be used for reporting
behavioral response threshold levels for criteria.
Todd et al. (2022) detected harbor porpoises with C-PODS before,
during, and after pile driving for an oil and gas platform from 2015-
2020. Pile driving single strike SEL at 750 m was 160-164 dB re 1
[micro]Pa\2\s. Porpoise detections significantly decreased at the
beginning of the construction project, but detections appeared to
return to baseline levels within 5 months. According to the authors,
the lack of significant trend over years indicated that porpoises
returned to the area and did not experience habitat displacement for
the entire 5-year period.
Physiological Responses and Stress
Elmegaard et al. (2021) exposed two captive harbor porpoises to
sonar sweeps (6-9 kHz, 500 msec duration, 50-100 msec rise time,
varying received levels (RL)) and pulsed sounds (50 msec duration, peak
frequency 40 kHz, half power bandwidth of ~5 kHz, rise time < 5 msec,
varying RL) to investigate startle reflex and changes in heart rate.
The sonar exposures did not elicit startle responses; the initial two
to three exposures induced bradycardia (a slow heart rate), with
subsequent habituation. This habituation was conserved after a 3-year
pause in exposures. The authors suggest that the initial bradycardia
allows ``a prolonged breath-hold to assess the nature of a novel
stimuli or flee in crypsis if needed;'' in na[iuml]ve wild cetaceans,
the reduced peripheral perfusion caused by this response may reduce
N<INF>2</INF> diffusion from supersaturated tissues during dive
ascents, increasing risk of decompression sickness. Startle responses
to the pulse exposures were directly correlated to RL. The 50 percent
motor-startle probability threshold was around 130 dB re 1 [mu]Pa
(rms50). This is ~85 dB above hearing threshold and is similar to that
observed in bottlenose dolphins (~90 dB over hearing threshold) (Gotz
et al. 2020). No significant change in heart rate was observed. The
authors suggest that the parasympathetic cardiac dive response may
override any transient sympathetic response, or that diving mammals may
not have the cardiac startle response seen in terrestrial mammals in
order to maintain volitional cardiovascular control at depth.
Fahlman et al. (2021) reviews decompression theory and the
mechanisms dolphins have evolved to prevent high N2 levels and gas
emboli (i.e., bends-like symptoms) in normal conditions. However, in
times of high stress, the selective gas exchange hypothesis states that
this mechanism can break down. In addition, circulating microparticles
may be useful biomarkers for decompression stress in cetaceans.
Yang et al. (2021) measured cortisol concentrations in blood
samples of two captive bottlenose dolphins and found significantly
higher levels after exposure to high sound level (140 dB re 1 [mu]Pa)
impulsive noise playbacks, compared to control and low sound levels (0
and 120 dB re 1 [mu]Pa, respectively). Six cytokine gene transcriptions
were also measured in blood samples and two (IL-10 and IFN-[gamma])
showed significant changes at high sound level exposure, compared to
control and low sound levels. Results suggest that repeated exposures
or sustained stress response to impulsive sounds may increase an
affected individual's susceptibility to pathogens, affect growth and
reproduction, etc. In addition, no avoidance behavior was observed
during the trials, indicating that stress-induced physiological changes
could be present despite the absence of behavioral changes.
Williams et al. (2022) measured physiological and behavioral
responses in narwhals in the Arctic during seismic airgun impulse
exposure compared to control conditions. Responses were measured using
heart rate-accelerometer-depth recorders and changes in locomotor,
cardiovascular, and respiratory responses were observed following
exposure. Airgun SELs, as received at 10 m depth during sound source
verifications, were approximately 152 dB re 1 [micro]Pa\2\s at 1 km
(0.5 nmi) range and decreased to approximately 120 dB re 1
[micro]Pa\2\s at 10 km (5.4 nmi) dives. The response to seismic and
vessel noise was a reduction in gliding descents and prolonged periods
of high intensity activity associated with periods of elevated stroke
frequencies. Noise exposure also resulted in periods of prolonged and
intense bradycardia (i.e., slowed heart rate). An increase in post-dive
respiratory rates occurred during recovery from noise-exposed dives
compared to control dives.
Stranding
Danil et al. (2021) document the findings of NOAA's investigation
of the strandings of three coastal bottlenose dolphins in 2015 at
Silver Strand Training Complex in NOAA Technical Memorandum NMFS-SWFSC-
641. On October 21, 2015, two dolphins were found stranded dead near
each other on the beach. Because a Navy major training exercise (MTE)
was underway, these strandings met the criteria of an Uncommon
Stranding Event in accordance with the Southern California Stranding
Response Plan in the Navy's Phase 2 LOA for HSTT. A third decomposed
dolphin was found in the same area 10 days later. Examination of the
dolphins resulted in findings indicative of severe acute trauma,
including lower jaw subcutaneous hemorrhage, emphysema, and cervical
blubber hemorrhage. Additional signs of injury to the cerebrum and
heart, or lipids in the lungs were also discovered. No hemorrhage was
found near the ears. At least two of the dolphins showed signs of
feeding before stranding, and all were in robust condition. There were
no external signs of strike or entanglement. These observations and
lack of others did not clearly determine the cause of the acute trauma.
Based on previous case studies, the investigators determined that
underwater detonation, peracute underwater entrapment (i.e., fisheries
interaction), or sonar were the most plausible causes. The Navy notes
that sonar has not been associated with these kinds of symptoms before,
nor has there ever been any association between dolphin mortality and
sonar. No anti-submarine (ASW) sonar or explosive use was associated
with the Navy MTE; however, unit level training with MF1 sonar occurred
on October 19 (for 35 minutes) and October 20 (62 minutes in total),
with sonar use as close as 6 nmi (11.1 km) to the stranding location.
No known squid or bait fishing efforts within U.S. waters occurred in
the vicinity preceding the strandings. The Navy notes that it is
unknown what fishing efforts occurred in Mexican territorial waters
immediately south of the stranding location.
Wang et al. (2021) conducted an auditory-evoked potential (AEP)
hearing test on a single stranded 19-year-old male melon-headed whale
in the 9.5--181 kHz frequency range. Tone pip trains were presented
underwater at a depth of 0.3 m and 1 m distance from the whale, and
AEPs were recorded by suction cup electrodes on the skin surface.
Hearing was measured in this
[[Page 68309]]
individual after it had been stranded and during attempted
rehabilitation in a concrete pool. Eighteen frequencies were measured
once, and eight frequencies were measured twice, yielding an audiogram
that showed elevated hearing thresholds (compared to the pygmy killer
whale) between 10 and 100 kHz. There are no data from normal-hearing
individuals of the melon-headed whale species to which this study's
data can be compared.
Population Consequences of Disturbance and Cumulative Stressors
Southall et al. (2021) provided updated guidance and methods to
assess the severity of behavioral responses by marine mammals to
several types of anthropogenic noise sources. The criteria developed in
the 2007 effort were updated by explicitly distinguishing between
captive and field studies, decoupling their respective severity scales,
and splitting the severity scale into three categories of foraging,
survival, and reproduction. In addition, the updated guidance changed
the categorization of noise sources and began to consider long term
consequences of exposures rather than just immediate responses.
Additional and consistent metrics to be reported in behavioral response
studies are recommended, including subject-specific metrics (e.g.,
functional hearing group, age class, sex, behavioral state, presence of
calf), exposure context metrics (e.g., exposure type, range to source,
source and animal depth, presence of other species or other noise
sources), and noise exposure metrics (e.g. exposure duration, rise
time, number of exposures, SPL [rms and p-p], SEL, SNR). The authors
then applied the severity scale to acute exposure studies using sonar
sources, continuous (industrial) sources, pile driving sources, and
airgun sources. For the long-term exposure analysis, a set of factors
developed by Bejder and Samuels (2003) were applied to long-term
studies on whale-watching and other long-term exposure or multi-
exposure datasets. These factors included metrics of short-term impacts
and long-term survival measures, characteristics of the studies, and
sources of anthropogenic disturbance. The applied examples of scoring
both acute and long-term studies of behavioral response provide a
framework for other researchers to apply the same metrics to their own
studies.
Migrating humpback whale mother-calf pairs' responses to seismic
surveys were modeled by Dunlop et al. (2021) using both a forwards and
backward approach. While a typical forwards approach can determine if a
stressor would have population-level consequences, authors demonstrated
that working backwards through a population consequences of disturbance
(PCoD) model can be used to assess the ``worst case'' scenario for an
interaction of a target species and stressor. Assumptions for the
extreme scenario were likely exaggerated (e.g., in area for > 48 hours,
exposed to > 3 air gun events) but lack data to inform humpback nursing
behavior and calf survivability during acoustic stressors. The results
demonstrated that migrating whales would not likely experience enough
of a delay as a result of disturbance to result in population
consequences, but whales disturbed in breeding or resting areas would
be more vulnerable to consequences of disturbance.
Greenfield et al. (2020) demonstrated that bottlenose dolphins who
had been injured from boat strike or entanglement experienced a decline
in their social network's preferred associations, and as a result were
more vulnerable to predation and less fecund.
Hin et al. (2021) used a previously published energy budget model
for pilot whales (Hin et al. 2019) to examine how lost foraging days
affect individuals in a population at carrying capacity. In this model,
depletion of prey is dependent on whale density, and prey density
limits the energy available for growth, reproduction, and survival. The
authors assumed extreme disturbance events for this study: consecutive
days of no foraging affecting all individuals in a population. The
undisturbed whale population was regulated through the effect of prey
availability on calf survival and pregnancy rates and on age at first
reproduction of females. During a disturbance event, population decline
was generally attributed to loss of lactating females and calves due to
reduced body condition. The subsequent increase in prey density and per
capita prey availability, however, resulted in improved body condition
in the population overall and decreased age at first calf. As
disturbance duration was increased (~40 days of no foraging), the
population would enter extreme decline towards extinction.
Murray et al. (2021) conducted a cumulative effects assessment on
Northern and Southern Resident killer whales, which involved both a
Pathways of Effects conceptual model and a Population Viability
Analysis quantitative simulation model. Authors found that both
populations were highly sensitive to prey abundance and were also
impacted by the interaction of low prey abundance with vessel strike,
vessel noise, and polychlorinated biphenyls contaminants. However, more
research is needed to validate the mechanisms of vessel disturbance and
environmental contaminants.
Pirotta et al. (2020) reformulated their previous dynamic energy
budget model (Pirotta et al. 2018) to investigate the state-dependent
life history strategies of female long-finned pilot whales and trade-
offs between their body condition (i.e., ability to offset starvation
during pregnancy and provide milk), prey availability, and decision to
reproduce in situations with and without disturbance. Many whales in
this model attempted to reproduce young, and while that had no cost in
situations without disturbance, young mothers would starve and die when
foraging was prevented by some disturbance event or because resources
were low (winter). Whale reproductive strategies resulted in lower
lifetime reproductive output, compared to the model used in Hin et al.
(2019).
Pirotta et al. (2021) integrated different sources of data (e.g.,
controlled exposure data, activity monitoring, telemetry tracking, and
prey sampling) into a bioenergetic model, which was used to predict
effects from sonar on a blue whale's daily energy intake. Approximately
half of the simulated whales had no change in daily net energy intake
because they either had no response or were not exposed. However, the
other half experienced a decrease in net energy intake. A portion (11
percent) of those simulated whales had negative net energy even after
brief (e.g., 6-30 min) or weak (e.g., 160-180 dB re 1 [mu]Pa source
level) events, which indicated that they would not be able to cover
that day's energetic cost. This dichotomy in results was due to the
variation in activity budgets, lunging rates and ranging patterns
between tagged whales. This evidence suggests that context can
influence the predicted costs of disturbance even more than body size
or prey density distribution on a daily scale (although prey
availability and abundance affected behavioral patterns).
Pirotta et al. (2022) evaluated potential long-term effects of
changing environmental conditions and military sonar by modeling vital
rates of Eastern North Pacific blue whales. Previous work from Pirotta
et al. (2021) was used as a foundation for incorporating the most
recent best available science into the vital rate model presented in
this study. Using data and underlying models of behavioral patterns,
energy budgets, body condition, contextual responses to noise, and prey
resources, the model predicted female vital rates
[[Page 68310]]
including survival (age at death), and reproductive success (number of
female calves). The model simulation results showed that
``[e]nvironmental changes were predicted to severely affect vital
rates, while the current regime of sonar activities was not.'' The case
study used an annual sonar regime in SOCAL based on the description of
the action in the Navy's 2018 HSTT FEIS/OEIS. Additional military sonar
scenarios were modeled, and a ten-fold increase in sonar activity
combined with a shift in geographical location to overlap with main
feeding areas of blue whales resulted in a moderate decrease in
lifetime reproductive success (Cohen's d = 0.47). However, there was no
effect on survival (Cohen's d = 0.05).
Pirotta (2022) covered the development of bioenergetic models
[``any mechanistic model where the principles of metabolic ecology are
used to describe how an individual animal acquires energy from food
resources (i.e., energy intake) and allocates assimilated energy to
various life history functions (i.e., energy costs, including
maintenance and survival, growth and reproduction)''] with a focus on
applications to marine mammals. This article provided a thorough
overview of the history of marine mammal bioenergetic models, defined
relevant terminology, and explained the differences between general
types of models.
McHuron et al. (2021) developed a state-dependent behavioral and
life history model to predict the probability of Western gray whale
mother-calf pair survival with and without acoustic disturbance and
with or without adequate prey availability on their summer foraging
grounds. Pregnant mother movement, feeding behavior, fat mass and fetal
length were input data for the model. Since prey availability was co-
dependent on whales having access to high-density offshore areas by
mid-July, nearshore seismic surveys had no impact on population
fecundity or mother-calf survival. This model overcomes a key challenge
in PCoD literature by providing a link between behavioral responses and
vital rates; authors recommend focusing on species that are data rich
to accurately characterize the biology of the focal species, metrics of
fitness, and key qualities of their environment.
Joy et al. (2022) presented a hypothetical case study for fin
whales off Southern California exposed to stationary single-ship 53C
sonar events over the course of a year, using the Navy's Phase 3
behavioral response function (BRF). Two model runs were compared: using
[alpha] = 0.05 (average 20-minute movement disruption) and [alpha]=
0.99 (average 3 days movement disruption). When animals returned to
baseline behavior after a short disturbance ([alpha] = 0.05), there was
less regional displacement and thus more instances of behavioral
disturbance over the course of a year. When animals returned to
baseline behavior after a longer period ([alpha]=0.99), there were
fewer instances of behavioral disturbances over the course of a year
due to cumulative displacement from habitat near the sonar source.
Keen et al. (2021) reviewed 15+ years of PCoD modeling and
identified the most critical factors for determining long-term impacts
to populations. Critical factors include life-history traits,
disturbance source characteristics, and environmental conditions. No
specific model or quantitative assessment was proposed.
Methodology for Assessing Acoustic Impacts
Palmer et al. (2022) recorded North Atlantic right whale upcalls
using 10 Marine Autonomous Recording Units deployed in Cape Cod Bay
from February to May 2009. A modified equation was provided for
determining the effective survey area, including a Lombard coefficient,
for single sensor applications. The authors state manual annotation or
verification is nearly always used to confirm automated detector
outputs prior to near-real-time conservation measures due to
limitations in automatic detector capabilities.
Aircraft Noise
Kuehne et al. (2020) measured in-air and underwater sound from low-
altitude EA-18G Growler flights in the immediate vicinity of Ault Field
at Naval Air Station Whidbey Island (NASWI). Data were collected by two
in-air recorders and one hydrophone placed just off the runway at a
depth of 30 meters. The underwater 10-flight average sound measurement
was 134 <plus-minus> 3 dB re 1 [mu]Pa rms in the highest 1-second
window. The results showed that the peak frequency range of the Growler
overflight noise both in air and underwater was between 50 and 1,000
Hz, which is typically a frequency range with high background noise
underwater, particularly in areas with large amounts of vessel traffic
(Erbe et al. 2012). The study did not include behavioral observations
of wildlife, and the authors' conclusions about potential impacts to
wildlife were unsupported by data from the study. In a separate effort,
Kuehne and Olden (2020) relied on volunteers to identify military
aircraft noise in recordings taken on land on the Olympic Peninsula.
This study also did not examine impacts to or responses by wildlife to
aircraft.
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 complete and
supportable, as stated in the 2018 HSTT final rule. Please see section
3.7 (Marine Mammals) of the 2018 HSTT FEIS/OEIS for additional
information.
Conclusion for New Pertinent Science Since Publication of the 2020 HSTT
Final Rule
Having considered the best scientific information available,
specifically new relevant information published since the 2020 HSTT
final rule, we have preliminarily 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 proposing
for authorization, 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 preliminarily 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 proposed 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
[[Page 68311]]
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).
Proposed authorized takes would primarily be in the form of Level B
harassment, as use of the acoustic and explosive sources (i.e., sonar,
air guns, pile driving, explosives) and 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. Proposed
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) and the number of days of activities or events.
Acoustic Thresholds
Using the best available science, NMFS, in coordination with the
Navy, has established acoustic thresholds that identify the most
appropriate received level of underwater sound above which marine
mammals exposed to these sound sources could be reasonably expected to
experience a disruption in behavior patterns to a point where they are
abandoned or significantly altered or to incur TTS (equated to Level B
harassment) or permanent threshold shift (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, none of which have changed, 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, we described new relevant information from the
scientific literature since publication of the 2018 HSTT final rule.
Since publication of the 2020 HSTT final rule, a number of additional
studies have published, including several associated with TTS in harbor
porpoises and seals (e.g., Kastelein et al. 2020d; Kastelein et al.
2021a and 2021b; Sills et al. 2020). NMFS is aware of these recent
papers, summarized above in the New Pertinent Science Since Publication
of the 2020 HSTT Final Rule section. NMFS is currently working with the
Navy to update NMFS' Technical Guidance for Assessing the Effects of
Anthropogenic Sound on Marine Mammal Hearing Version 2.0 (Acoustic
Technical Guidance; NMFS 2018) to reflect relevant papers that have
been published since the 2018 update on our 3-5 year update schedule in
the Acoustic Technical Guidance. First, we note that the recent peer-
reviewed updated marine mammal noise exposure criteria by Southall et
al. (2019) provide identical PTS and TTS thresholds and weighting
functions to those provided in NMFS' Acoustic Technical Guidance.
NMFS will continue to review and evaluate new relevant data as it
becomes available and consider the impacts of those studies on the
Acoustic Technical Guidance to determine what revisions or updates may
be appropriate. However, any such revisions must undergo peer and
public review before being adopted, as described in the Acoustic
Technical Guidance methodology. While some of the relevant data may
potentially suggest changes to TTS/PTS thresholds for some species, any
such changes would not be expected to change the predicted take
estimates in a manner that would change the necessary determinations
supporting the issuance of these regulations, and the data and values
used in this proposed rule reflect the best available science.
Navy's Acoustic Effects Model
The Navy proposes 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.
Range to Effects
The Navy proposes 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 proposed rule, including equipment and sources used and
exercises conducted. NMFS has reviewed and will continue to review and
evaluate new relevant data as it becomes available and consider the
impacts of those studies on the Acoustic Technical Guidance to
determine what revisions/updates may be appropriate. However, any such
revisions must undergo peer and public review before being adopted, as
described in the Acoustic Guidance methodology. While some of the
relevant data may potentially suggest changes to TTS/PTS thresholds for
some species (e.g., Kastelein et al. (2020a) shows onset of TTS
incurred by a harbor porpoise at higher received levels than would have
been anticipated based on the existing criteria, while Kastelein et al.
(2022a) shows onset of TTS in otariids in water at lower received
levels than the existing criteria), our assessment suggests that any
such changes would not be expected to change the predicted take
estimates in a manner that would change the necessary determinations
supporting the issuance of these regulations, and the data and values
used in the 2018 HSTT final rule, 2020 HSTT final rule, and this
proposed rule reflect the best available science. Therefore, the ranges
to effects in this proposed 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.
[[Page 68312]]
Marine Mammal Density
The Navy proposes 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 2022 final SARs (Carretta et al. 2023, Young et al.
2023). 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, 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:
<bullet> Acoustics (sonar and other transducers; air guns; pile
driving/extraction);
<bullet> Explosives (explosive shock wave and sound, assumed to
encompass the risk due to fragmentation); and
<bullet> 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 proposed to be 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 proposes to use 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 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 Preliminary 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
[[Page 68313]]
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 Requested Take From Training and Testing Activities
Based on the methods discussed in the previous sections and the
Navy's model and quantitative assessment of mitigation, the Navy
provided its take estimate and request for authorization of takes
incidental to the use of acoustic and explosive sources for training
and testing activities both annually (based on the maximum number of
activities that could occur per 12-month period) and over the 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 Estimated
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 proposed 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 Estimated Harassment Take from Testing Activities
and Estimated Harassment Take from Training Activities sections below
for the estimated annual and 7-year total number and type of Level A
harassment and Level B harassment for each humpback whale stock.
Estimated 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 requested no change to this authorized take,
though as described above, NMFS has since published the 2022 final
SARs, 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.
[[Page 68314]]
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.
Estimated 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.
Estimated 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
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
[[Page 68315]]
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, slow-moving 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 i
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