Rule2024-08257
Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Geophysical Surveys in the Gulf of Mexico
Primary source
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Published
April 24, 2024
Effective
May 24, 2024
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has reassessed the statutorily mandated findings supporting its January 19, 2021 final rule, "Regulations Governing Taking Marine Mammals Incidental to Geophysical Survey Activities in the Gulf of Mexico," issued pursuant to the Marine Mammal Protection Act (MMPA), as the estimates of incidental take of marine mammals anticipated from the activities analyzed for the 2021 final rule were erroneous. NMFS has corrected this error and considered and incorporated other newly available and pertinent information relevant to the analyses supporting some of the findings in the 2021 final rule and the taking allowable under the regulations. There are no changes to the specified activities or the specified geographical region in which those activities would be conducted, nor to the original 5-year period of effectiveness. In light of the new information, NMFS presents new analyses supporting our affirmance of the negligible impact determinations for all species, and affirms that the existing regulations, which contain mitigation, monitoring, and reporting requirements, are consistent with the "least practicable adverse impact (LPAI) standard" of the MMPA.
Full Text
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[Federal Register Volume 89, Number 80 (Wednesday, April 24, 2024)]
[Rules and Regulations]
[Pages 31488-31541]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-08257]
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Vol. 89
Wednesday,
No. 80
April 24, 2024
Part IV
Department of Commerce
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National Oceanic and Atmospheric Administration
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50 CFR Part 217
Taking and Importing Marine Mammals; Taking Marine Mammals Incidental
to Geophysical Surveys in the Gulf of Mexico; Final Rule
Federal Register / Vol. 89 , No. 80 / Wednesday, April 24, 2024 /
Rules and Regulations
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 217
[Docket No. 240410-0195]
RIN 0648-BL68
Taking and Importing Marine Mammals; Taking Marine Mammals
Incidental to Geophysical Surveys in the Gulf of Mexico
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Final rule.
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SUMMARY: NMFS has reassessed the statutorily mandated findings
supporting its January 19, 2021 final rule, ``Regulations Governing
Taking Marine Mammals Incidental to Geophysical Survey Activities in
the Gulf of Mexico,'' issued pursuant to the Marine Mammal Protection
Act (MMPA), as the estimates of incidental take of marine mammals
anticipated from the activities analyzed for the 2021 final rule were
erroneous. NMFS has corrected this error and considered and
incorporated other newly available and pertinent information relevant
to the analyses supporting some of the findings in the 2021 final rule
and the taking allowable under the regulations. There are no changes to
the specified activities or the specified geographical region in which
those activities would be conducted, nor to the original 5-year period
of effectiveness. In light of the new information, NMFS presents new
analyses supporting our affirmance of the negligible impact
determinations for all species, and affirms that the existing
regulations, which contain mitigation, monitoring, and reporting
requirements, are consistent with the ``least practicable adverse
impact (LPAI) standard'' of the MMPA.
DATES: Effective from May 24, 2024 through April 19, 2026.
ADDRESSES: Electronic copies of the application and supporting
documents, as well as a list of the references cited in this document,
may be obtained online at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>. In case of problems accessing these documents,
please call the contact listed below.
FOR FURTHER INFORMATION CONTACT: Ben Laws, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Purpose and Need for Regulatory Action
On January 19, 2021 (86 FR 5322), in response to a petition request
from the Bureau of Ocean Energy Management (BOEM), NMFS issued a final
rule under the MMPA, 16 U.S.C. 1361 et seq., for regulations governing
the take of marine mammals incidental to the conduct of geophysical
survey activities in the Gulf of Mexico (GOM). This incidental take
regulation (ITR), which became effective on April 19, 2021, established
a framework to allow for the issuance of Letters of Authorization (LOA)
to authorize take by individual survey operators (50 CFR 216.106; 86 FR
5322 (January 19, 2021)). Take is expected to occur by Level A and/or
Level B harassment incidental to use of active sound sources as
described below.
Errors in the estimates of the maximum annual and 5-year take
numbers, discovered during implementation of the ITR, preclude NMFS
from issuing LOAs for the full amount of activity described by BOEM in
the petition (as revised) and intended to be covered under the ITR. As
a result, the utility of the ITR has been limited. NMFS has produced
corrected take estimates, including updates to the best available
science incorporated into the take estimation process (i.e., new marine
mammal density information). Changes to the take numbers required
additional analysis to ensure that the necessary statutory findings can
still be made. This rule revises NMFS' analysis and affirms the
statutory findings that underlie its January 19, 2021, final rule (86
FR 5322), based on consideration of information that corrects and
updates the take estimates that were considered for the 2021 final
rule.
Legal Authority for the Action
Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) directs
the Secretary of Commerce 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 for up to 5 years if,
after notice and public comment, the agency makes certain findings and
issues regulations that set forth permissible methods of taking
pursuant to that activity and other means of effecting the LPAI on the
affected species or stocks and their habitat (see the discussion below
in the Mitigation section), as well as monitoring and reporting
requirements. Under NMFS' implementing regulations for section
101(a)(5)(A), NMFS issues LOAs to individuals (including entities)
seeking authorization for take under the activity-specific incidental
take regulations (50 CFR 216.106).
Summary of Major Provisions Within the Regulations
Following is a summary of the major provisions of the current ITR
regarding geophysical survey activities, which NMFS reaffirms through
this rulemaking. The regulations contain requirements for mitigation,
monitoring, and reporting, including:
<bullet> Standard detection-based mitigation measures, including
use of visual and acoustic observation to detect marine mammals and
shut down acoustic sources in certain circumstances;
<bullet> A time-area restriction designed to avoid effects to
bottlenose dolphins in times and places believed to be of particular
importance;
<bullet> Vessel strike avoidance measures; and
<bullet> Monitoring and reporting requirements.
See 50 CFR 217.180 et seq. The ITR continues to govern and allow
for the issuance of LOAs for the take of marine mammals incidental to
the specified activity (which is unchanged from what was described in
the 2021 final rule), within the upper bounds of take evaluated herein.
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, a notice of a
proposed incidental take authorization may be provided to the public
for review.
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 LPAI on the affected species
or stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance, and on the
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availability of the species or stocks for taking for certain
subsistence uses (referred to as ``mitigation''); and set forth
requirements pertaining to the monitoring and reporting of the takings.
The definitions of all applicable MMPA statutory terms cited above are
included in the relevant sections below.
On October 17, 2016, BOEM submitted a revised petition \1\ to NMFS
for rulemaking under section 101(a)(5)(A) of the MMPA to authorize take
of marine mammals incidental to conducting geophysical surveys during
oil and gas industry exploration and development activities in the GOM.
This revised petition was deemed adequate and complete based on NMFS'
implementing regulations at 50 CFR 216.104.
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\1\ In the 2018 notice of proposed rulemaking (83 FR 29212, June
22, 2018), NMFS provided a brief history of prior petitions received
from BOEM's predecessor agencies.
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NMFS published a notice of proposed rulemaking in the Federal
Register for a 60-day public review on June 22, 2018 (83 FR 29212)
(``2018 proposed rule''). All comments received are available online at
<a href="http://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>.
On February 24, 2020, BOEM submitted a notice to NMFS of its
``updated proposed action and action area for the ongoing [ITR]
process[.]'' This update consisted of removal of the area then under a
Congressional leasing moratorium under the Gulf of Mexico Energy
Security Act (GOMESA) (Sec. 104, Pub. L. 109-432) \2\ from
consideration in the ITR. BOEM stated in its notice that survey
activities are not likely to be proposed within the area subject to the
leasing moratorium during the 5-year period of effectiveness for the
ITR and, therefore, that the ``number, type, and effects of any such
proposed [survey] activities are simply too speculative and uncertain
for BOEM to predict or meaningfully analyze.'' Based on this updated
scope, BOEM on March 26, 2020, submitted revised projections of
expected activity levels and corresponding changes to modeled acoustic
exposure numbers (i.e., take estimates). BOEM's notice and updated
information are available online at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>. NMFS incorporated this change in scope
with the revised take estimates and issued a final rule and ITR on
January 19, 2021 (86 FR 5322) (``2021 final rule'' or ``2021 ITR''),
which became effective on April 19, 2021. Consistent with section
101(a)(5)(A) and NMFS' implementing regulations, NMFS may issue LOAs
under the 2021 ITR for a period of 5 years.
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\2\ The Congressional moratorium in GOMESA was in place until
June 30, 2022. On September 8, 2020, the President withdrew, under
section 12 of the Outer Continental Shelf Lands Act, the same area
covered by the prior GOMESA moratorium from disposition by leasing
for 10 years, beginning on July 1, 2022, and ending on June 30,
2032.
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While processing requests for individual LOAs under the ITR using
the methodology for developing LOA-specific take numbers presented in
the 2021 final rule, NMFS discovered that the estimated maximum annual
incidental take and estimated total 5-year take from all survey
activities that BOEM projected for its revised scope appeared to be in
error, in that maximum annual incidental take was likely to be reached
much sooner than anticipated for some species based on the level of
activity described in BOEM's petition as revised in 2020. NMFS
contacted BOEM regarding this, and BOEM determined that, when it
reduced its scope of specified activity in March 2020 by removing the
GOMESA moratorium area from its proposed action, it underestimated the
level of take by inadvertently factoring species density estimates into
its revised exposure estimates twice. Generally, this miscalculation
caused BOEM to underestimate the total predicted exposures of species
from all survey activities in its revision to the petition, most
pronouncedly for those species with the lowest densities (e.g., killer
whales).
BOEM provided NMFS with an explanation of the miscalculation with
regard to its incidental take estimate and revised take estimates,
which is available online at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>. See the Estimated Take section for additional
discussion. NMFS then determined it would conduct a rulemaking to
analyze the revised take estimates and, if appropriate, revise its
incidental take rule accordingly. On January 5, 2023, NMFS published a
proposed rule, requesting comments for a period of 30 days on its
revised negligible impact analyses and proposed findings and proposed
retention of the existing regulations as consistent with the MMPA's
LPAI standard (88 FR 916, January 5, 2023).
Our proposed and final rule together provide analysis of the same
activities and activity levels considered for the 2021 final rule, for
the original 5-year period, and utilize the same modeling methodology
described in the 2021 final rule. We incorporate the best available
information, including consideration of specific new information that
has become available since the 2021 rule was published, and updates to
currently available marine mammal density information. We also
incorporate expanded modeling results that estimate take utilizing the
existing methodology but also consider the effects of using smaller
(relative to the proxy source originally defined by BOEM) airgun arrays
currently prevalent, as evidenced by LOA applications received by NMFS
to date (see <a href="https://www.fisheries.noaa.gov/issued-letters-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/issued-letters-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>).
There are no changes to the nature or level of the specified
activities within or across years or to the geographic scope of the
activity. Based on our assessment of the specified activity in light of
the revised take estimates and other new information, we have
determined that the 2021 ITR at 50 CFR 217.180 et seq., which include
the required mitigation and associated monitoring measures, satisfy the
MMPA requirement to prescribe the means of effecting the LPAI on the
affected species or stocks and their habitat, and therefore, do not
change those regulations, nor do we change the requirements pertaining
to monitoring and reporting. This rulemaking supplements the
information supporting the 2021 incidental take rule. This rule does
not change the existing April 19, 2026, expiration date of the 2021
ITR. In addition, NMFS' demarcation of ``years'' under the 2021 final
rule for purposes of accounting for authorized take (e.g., Year 1 under
the rule extended from April 19, 2021, through April 18, 2022) remains
unchanged under this rule.
As to the negligible impact findings, the revised take numbers
remain within those previously analyzed for most species. (Take numbers
increased compared with the 2021 final rule for 4 species: Rice's whale
(formerly Bryde's whale), Fraser's dolphin, rough-toothed dolphin, and
striped dolphin. See tables 5 and 6. Because of the new category of
``blackfish,'' there is uncertainty on any change in the take numbers
for the individual species that comprise that category, though
collectively the take numbers for all species in the blackfish category
remain within the levels previously analyzed.) However, we revisited
the risk assessment framework used in analyses for the 2021 final rule
for all species, as elements of the framework are dependent on
information related to stock abundance,
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which has been updated (Hayes et al., 2021; Garrison et al., 2023). For
most species, we provide updated negligible impact analyses and
determinations. For those species for which take numbers decreased and
associated evaluated risk remained static or declined, we incorporate
(by either repeating, summarizing, or referencing) applicable
information and analyses in the prior rulemaking and supporting
documents. For those species, there is no other new information
suggesting that the effect of the anticipated take might exceed what
was considered in the 2021 final rule. Therefore, the analyses and
findings provided in the 2021 final rule remain current and applicable.
Please see the Negligible Impact Analysis and Determinations section
for further information. As to the small numbers standard, we do not
change the interpretation and implementation as laid out in the 2021
final rule (86 FR 5322, 5438, January 19, 2021).
Description of the Specified Activity
Overview
The specified activity for this action is unchanged from the
specified activity considered for the 2021 ITR, consisting of
geophysical surveys conducted for a variety of reasons. BOEM's 2016
petition described a 10-year period of geophysical survey activity and
provided estimates of the amount of effort by survey type and location.
BOEM's 2020 update to the scope of activity included revisions to these
level-of-effort projections, including reducing the projections to 5
years and removing activity assumed to occur within the areas removed
from the scope of activity. Actual total amounts of effort (including
by survey type and location) are not known in advance of receiving LOA
requests, but take in excess of what is analyzed in this rule would not
be authorized. Applicants seeking authorization for take of marine
mammals incidental to survey activities outside the geographic scope of
the rule (i.e., within the former GOMESA moratorium area) would need to
pursue a separate MMPA incidental take authorization. See Figures 1 and
2.
Geophysical surveys in the GOM are typically conducted in support
of hydrocarbon exploration, development, and production by companies
that provide such services to the oil and gas industry. Broadly, these
surveys include deep penetration surveys using large airgun arrays as
the acoustic source; shallow penetration surveys using a small airgun
array, single airgun, or other systems that may achieve similar
objectives (here considered broadly as including other similar sources
such as boomers and sparkers) as the acoustic source; or high-
resolution surveys, which may use a variety of acoustic sources.
Geophysical surveys and associated acoustic sources were described in
detail in NMFS' 2018 notice of proposed rulemaking and in the notice of
issuance for the 2021 final rule (83 FR 29212, June 22, 2018; 86 FR
5322, January 19, 2021). Please refer to those notices for detailed
discussion of geophysical survey operations, associated acoustic
sources, and the specific sources and survey types that were the
subject of acoustic exposure modeling. Information provided therein
remains accurate and relevant and is not repeated here. The use of
these acoustic sources produces underwater sound at levels that have
the potential to result in harassment of marine mammals. Marine mammal
species with the potential to be present in the GOM are described below
(see table 2).
The specified geographical region is illustrated below but
generally speaking, survey activity may occur within U.S. territorial
waters and waters of the U.S. Exclusive Economic Zone (EEZ) within the
GOM (i.e., to 200 nautical miles (nmi)), except for the former GOMESA
moratorium area).
Dates and Duration
The dates and duration of the specified activities considered for
this rule are unchanged from the dates and duration for the 2021 final
rule, which may occur at any time during the period of validity of the
regulations (April 19, 2021, through April 18, 2026).
Specified Geographical Region
The specified geographical region for this action is unchanged from
the one considered for the 2021 final rule. The OCS planning areas are
depicted in Figure 1, and the specified geographical region (with the
modeling zones and depicting the area withdrawn from leasing
consideration) is depicted in Figure 2. NMFS provided a detailed
discussion of the specified geographical region in the 2018 notice of
proposed rulemaking.
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Summary of Representative Sound Sources
The 2021 final rule allows for the authorization of take, through
LOAs, incidental to use of airgun sources of different sizes and
configurations (as well as similar sources). The supporting modeling
considered two specific airgun array sizes/configurations (as well as a
single airgun). Acoustic exposure modeling performed in support of the
2021 rule was described in detail in ``Acoustic Propagation and Marine
Mammal Exposure Modeling of Geological and Geophysical Sources in the
Gulf of Mexico'' and ``Addendum to Acoustic Propagation and Marine
Mammal Exposure Modeling of Geological and Geophysical Sources in the
Gulf of Mexico'' (Zeddies et al., 2015, 2017a), as well as in ``Gulf of
Mexico Acoustic Exposure Model Variable Analysis'' (Zeddies et al.,
2017b), which evaluated a smaller, alternative airgun array. For this
final rule, modeling of a third airgun array size that is also smaller
than the original large array and more representative of survey
activities occurring under the current rule was specifically considered
(Weirathmueller et al., 2022). These reports provide full detail
regarding the modeled acoustic sources and survey types and are
available online at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>.
Representative sources for the modeling include three different
airgun arrays, a single airgun, and an acoustic source package
including a CHIRP sub-bottom profiler in combination with multibeam
echosounder and side-scan sonar. Two major survey types were
considered: large-area (including 2D, 3D narrow azimuth (NAZ), 3D wide
azimuth (WAZ), and coil surveys) and small-area (including single
airgun surveys and high-resolution surveys; the single airgun was used
as a proxy for surveys using a boomer or sparker). The nominal airgun
sources used for analysis of the specified activity include a single
airgun (90-cubic inch (in\3\) airgun) and a large airgun array (72-
element, 8,000 in\3\). In addition, the Model Variable Analysis
(Zeddies et al., 2017b) provides analysis of an alternative 4,130-in\3\
array, and the most recent modeling effort using the same methodology
provides analysis of a 32-element, 5,110-in\3\ array (Weirathmueller et
al., 2022), with specifications defined by NMFS in consultation with
industry operators to provide exposure modeling results more relevant
to arrays commonly in use (see Letters of Authorization section).
Additional discussion is provided in the Estimated Take section.
While it was necessary to identify representative sources for the
purposes of modeling take estimates for the analysis for the 2021 rule,
the analysis is intended to be, and is appropriately, applicable to
takes resulting from the use of other sizes or configurations of
airguns (e.g., the smaller, 5,110-in\3\ airgun array currently
prevalent in GOM survey effort and described in Weirathmueller et al.
(2022), and the alternative 4,130-in\3\ array initially modeled by
Zeddies et al. (2017b)). Although the analysis herein is based on the
modeling results presenting the highest estimated take number for each
species (for most species, those resulting from use of the 8,000-in\3\
array), actual take numbers for authorization through LOAs are
generated based on the results most applicable to the array planned for
use.
While these descriptions reflect existing technologies and current
practice, new technologies and/or uses of existing technologies may
come into practice during the remaining period of validity of these
regulations. As stated in the 2021 final rule (86 FR 5322, 5442;
January 19, 2021), NMFS will evaluate any such developments on a case-
specific basis to determine whether expected impacts on marine mammals
are consistent with those described or referenced in this document and,
therefore, whether any anticipated take incidental to use of those new
technologies or practices may appropriately be authorized under the
existing regulatory framework. See Letters of Authorization for
additional information.
Estimated Levels of Effort
As noted above, estimated levels of effort are unchanged from those
considered in the 2021 final rule. Please see the 2021 final rule
notice for additional detailed discussion of those estimates and of the
approach to delineating modeling zones (shown in Figure 2).
In support of its 2020 revision of the scope of the rule, BOEM
provided NMFS with revised 5-year level of effort predictions and
associated acoustic exposure estimates. Table 1 provides those effort
projections for the 5-year period, which are unchanged. This table
corrects table 2 in NMFS' notice of issuance of the 2021 ITR, which
erroneously presented the difference in activity levels between the
2018 proposed ITR and the revised levels after GOMESA removal. The
correct information was used in the take calculations, and was
concurrently made available to the public via BOEM's 2020 notice to
NMFS of its updated scope.
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The preceding description of the specified activity is a summary of
critical information. The interested reader should refer to the 2018
notice of proposed rulemaking (83 FR 29212, June 22, 2018), as well as
BOEM's petition (with addenda) and Programmatic Environmental Impact
Statement (PEIS), for additional detail regarding these activities and
the region.
Comments and Responses
NMFS published a notice of proposed rulemaking in the Federal
Register on January 5, 2023 (88 FR 916), beginning a 30-day comment
period. In that notice, we requested public input on the proposed rule,
including but not limited to NMFS' proposed or preliminary findings,
determinations, or conclusions regarding the MMPA standards, and the
information NMFS relies on in support of those findings,
determinations, or conclusions; and NMFS' preliminary decisions to
reaffirm or not make changes to the 2021 final rule, and the
information NMFS relies on in support of those preliminary decisions,
and requested that interested persons submit relevant information,
suggestions, and comments.
During the 30-day comment period, we received 22,832 comment
letters. Of this total, we determined that approximately 71 comment
letters represented unique submissions, including 6 letters from
various organizations (described below) and 65 unique submissions from
private citizens. The remaining approximately 22,756 comment letters
followed a generic template format in which respondents provided
comments that were identical or substantively the same. (For purposes
of counting, we considered comments using this template as a single
unique submission.)
A letter was submitted jointly by the EnerGeo Alliance (formerly
the International Association of Geophysical Contractors), the American
Petroleum Institute, the National Ocean Industries Association, and the
Offshore Operators Committee (hereafter, the ``Associations''). A
separate letter was submitted jointly by the Natural Resources Defense
Council (NRDC), Association of Zoos and Aquariums, Center for
Biological Diversity, Earthjustice, Healthy Gulf, and Surfrider
Foundation (hereafter, ``NRDC''). Additional letters were submitted by
the following: Beacon Offshore Energy (Beacon), BOEM, Chevron USA Inc.
(Chevron), and the Marine Mammal Commission (MMC). We note that several
of these entities refer to, or restate, comments they provided in
response to NMFS' 2018 proposed rulemaking--in some cases appending the
entirety of the 2018 letters to the current comment letters, and
stating that the 2018 comments are incorporated to the current
comments. All comments received in response to the 2018 proposed
rulemaking were previously responded to by NMFS (86 FR 5322, January
19, 2021). Where new information or context warranted additional
response to the prior comments, we provide it here. However, in most
cases no new response is required, and we rely on our prior responses
in the 2021 final rule.
NMFS has reviewed all public comments received on the 2023 proposed
rule. All relevant comments and our responses are described below. All
comments received are available online at: <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
A direct link to these comments is provided at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>.
General Comments
A large majority of commenters, including all of those following
the aforementioned generic template, expressed general opposition
towards oil and gas industry geophysical survey activity, suggesting
that NMFS has decision-making authority regarding whether such surveys
occur. Numerous letters also provide commentary regarding climate
change and the relative merits of U.S. use of various sources of
energy. As these comments are outside the scope of NMFS' authority and
NMFS' decision under the MMPA, we do not respond further. NMFS' action
here concerns only the authorization of marine mammal take incidental
to projected geophysical surveys, provided that the required analyses,
findings, and other requirements have been satisfied. Jurisdiction
concerning decisions to allow the surveys themselves rests solely with
BOEM, pursuant to its authority under the Outer Continental Shelf Lands
Act (OCSLA). We also note that this rulemaking addresses only marine
mammals (and their habitat). As such, effects of the surveys on other
aspects of the marine environment are not relevant to NMFS' analyses
and authorities under section 101(a)(5)(A) of the MMPA.
In addition, numerous commenters (including all of those following
the aforementioned generic template) make unsupported assertions
regarding the potential impacts of oil and gas industry geophysical
survey activity, stating that such activity can deafen and cause the
death of marine mammals. As the commenters provide no evidence in
support of these assertions, and NMFS is not aware of any such
evidence, we do not respond further to these comments.
Comment: Beacon states that it appreciates NMFS' efforts to correct
previous errors, consider newly available and pertinent information,
and acknowledge the impact of those factors on the analyses supporting
prior findings in the 2021 final rule and the taking allowable under
applicable regulations. Beacon also states that it supports the
comments submitted by the Associations.
Response: NMFS appreciates the comments.
Comment: NRDC, noting that the purported projected levels of effort
provided in table 2 of NMFS' 2021 final rule were unaccountably low and
likely in error, requests confirmation that the activity levels
presented in NMFS' 2023 proposed rule are correct and that these levels
were used to generate the current estimated take numbers.
Response: NMFS confirms that the projected levels of effort
provided in table 1 of its 2023 proposed rule (and in this final rule)
are correct, and were used to generate the estimated take numbers
provided in table 6. Table 1 corrected table 2 in NMFS' 2021 final
rule, which erroneously presented the difference in activity levels
between the 2018 proposed ITR and the revised levels after GOMESA
removal. The correct projected levels of effort were used in the
analyses presented in NMFS' 2018 proposed rule, 2021 final rule, 2023
proposed rule, and this final rule.
Comment: The Associations assert that NMFS has ``declined to
provide the model inputs and outputs'' associated with acoustic
exposure modeling performed in support of the rule, and state that this
precludes the public from conducting a thorough review of the proposed
rule. The Associations separately reference the requirements of the
Administrative Procedure Act (APA) in asserting that NMFS has failed to
``fully disclose all necessary information about the models it uses
(including all inputs and outputs), explain the assumptions and
methodology used to prepare the models, allow for public review and
feedback on the models and all related supporting information, and
respond to public comments and make changes to the models as warranted
based on those comments.''
Response: NMFS has provided information regarding all model inputs
and outputs, as well as information regarding all other aspects of the
[[Page 31495]]
modeling process. In association with its 2018 proposed rulemaking,
NMFS made the modeling report (Zeddies et al., 2015, 2017a) available
for public review for 60 days. This almost 400-page report includes
full detail regarding all model inputs and outputs, assumptions, and
methodology. Prior to the 60-day comment period for NMFS' 2018 proposed
rulemaking, the report was made available for review and comment during
NMFS' 45-day notice of receipt comment period regarding BOEM's
petition, as well as during a separate 60-day comment period for BOEM's
draft PEIS. Thus, this report was available for public review for a
minimum aggregate of 165 days prior to the 30-day comment period for
NMFS' 2023 proposed rule. Details regarding the 4,130-in\3\ airgun
array were provided by the Associations themselves in support of
development of their 2017 Gulf of Mexico Acoustic Exposure Model
Variable Analysis (Zeddies et al., 2017b), which was also provided for
public review during the 60-day comment period for NMFS' 2018 proposed
rule (and which also remains available to the public online at <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>). In order to
perform this modeling variable analysis, the Associations were granted
access to all modeling products and worked directly with the contracted
modelers (JASCO Applied Sciences(JASCO)).
NMFS further explained in its 2023 proposed rule that ``all aspects
of the modeling (including source, propagation, and animal movement
modeling) are the same as described in Zeddies et al. (2015, 2017a,
2017b) and discussed in previous Federal Register notices associated
with the ITR,'' with the exception of the introduction of a new source
(the 5,110-in\3\ array), details of which were provided in the
Weirathmueller et al. (2022) memorandum provided for public review
during the 30-day comment period for the 2023 proposed rule. (We note
that the Associations claim that ``NMFS provides insufficient
information. . .to determine whether this specific array size and the
configuration analyzed are accurate or representative. . . .'' However,
the Associations do not specify what necessary information they believe
was omitted from description of the array.)
The Associations do not describe any specific model inputs or
outputs or other information that they believe to have been withheld,
or specifically describe any assumptions or methodology that they
believe has been insufficiently explained. However, during the public
comment period, EnerGeo contacted NMFS to request the following:
<bullet> Model outputs, specifically the modeled sound pressure
levels across depth and range for all modeled radials for modeled
seismic arrays and modeling locations/seasons.
Upon receipt of this request, NMFS contacted JASCO to ascertain the
availability of the requested products (which are specific output files
rather than the descriptions of model outputs that are provided in the
modeling report). NMFS then communicated with EnerGeo that JASCO could
provide the requested sound field files, but noted that there are
several thousand files for each array volume, and that the files are in
a proprietary format. Therefore, NMFS explained to EnerGeo that the
request would require coordination between EnerGeo and JASCO in order
to produce the requested volume of files in a format that might be
useful to EnerGeo, and requested EnerGeo's response on how to conduct
the necessary coordination. EnerGeo did not respond.
<bullet> At each modeling location, the specific geographic
location of the centerpoint, the number of radials modeled, and the
specific inputs used in the modeling including bathymetry, sound speed
profiles, and the geoacoustic parameters of the seabed, as well as the
sea surface assumption (sea state or other assumptions).
Regarding this request, NMFS reiterated to EnerGeo the explanation
provided in the proposed rule: all of the requested information remains
unchanged from the original modeling effort and is described in the
original modeling report. However, NMFS noted that if EnerGeo could
specify any needed information that it could not find in the modeling
report, NMFS would work to provide it. EnerGeo did not respond.
<bullet> Summarized metrics on R<INF>95</INF><not-eq> and
R<INF>max</INF> distances \3\ to the 160-dB behavioral threshold, the
behavioral step function (for beaked whales and all other species), and
the hearing group-specific distances to Level A harassment thresholds
for the NMFS-specified sound exposure level (SEL) and peak thresholds
and for all modeled seismic arrays and acoustic modeling sites and
seasons.
---------------------------------------------------------------------------
\3\ Given a regularly gridded spatial distribution of sound
levels, the R<INF>95</INF><not-eq> for a given sound level was
defined as the radius of the circle, centered on the source,
encompassing 95 percent of the grid points with sound levels at or
above the given value. This definition is meaningful in terms of
potential impact to animals because, regardless of the shape of the
contour for a given sound level, R<INF>95</INF><not-eq> is the range
from the source beyond which less than 5 percent of a uniformly
distributed population would be exposed to sound at or above that
level. The R<INF>max</INF> for a given sound level is simply the
distance to the farthest occurrence of the threshold level
(equivalent to R<INF>100</INF><not-eq>. It is more conservative than
R<INF>95</INF><not-eq>, but may overestimate the effective exposure
zone. For cases where the volume ensonified to a specific level is
discontinuous and small pockets of higher received levels occur far
beyond the main ensonified volume, R<INF>max</INF> would be much
larger than R<INF>95</INF><not-eq> and could therefore be misleading
if not given along with R<INF>95</INF><not-eq> (Zeddies et al.,
2015).
---------------------------------------------------------------------------
Regarding this request, NMFS explained to EnerGeo that JASCO did
not specifically calculate R<INF>95</INF><not-eq> and R<INF>max</INF>
for every site, because R<INF>max</INF>/R<INF>95</INF><not-eq> are not
used for animal movement modeling--the entire sound fields are used.
Acoustic ranges were calculated for a subset of the modeled sites in
order to provide examples in the modeling report.
NMFS reiterates that the Associations provide no specific
information regarding any aspect of the modeling that they believe has
been inappropriately withheld from the public. Moreover, NMFS made a
good faith effort to respond to EnerGeo's request for information
during the public comment period, and EnerGeo neither followed up with
additional questions nor responded to NMFS' offer to facilitate a
working interaction with the modelers to obtain requested data files.
NMFS has provided all details regarding model inputs and outputs, as
well as modeling assumptions and methods, and has provided the public
with a meaningful opportunity for review. NMFS has further responded to
all comments, both here and in its 2021 final rule.
Comment: Chevron states that NMFS ignores real-world observations
that ``directly contradict'' its model estimates.
Response: Chevron refers to observations, or lack thereof, by
protected species observers (PSO) aboard survey vessels, as proof that
NMFS' take estimates are overly conservative. However, PSOs are able to
conduct observations over only a relatively small fraction of the area
in which marine mammals may be impacted by noise from seismic surveys
even during daylight hours, and many marine mammals are not observable
at the surface. Similarly, many marine mammals may not be detected by
acoustic monitoring. Lack of observations does not demonstrate that
takes of marine mammals do not occur. Moreover, we incorporated the
best available scientific information for our analysis, as evidenced
(for example) by
[[Page 31496]]
our references to BOEM's synthesis studies of PSO data from 2002-15
(Barkaszi et al., 2012; Barkaszi and Kelly, 2018) (as well as other
similar syntheses from other locations).
Comment: The Associations reiterate comments made initially with
regard to NMFS' 2018 proposed rule, asserting that NMFS has employed an
``unlawful'' approach to the estimation of incidental take, including
analyses of ``unlikely worst-case scenarios,'' resulting in
``significant overestimates of take.'' Chevron echoes these concerns.
Response: The commenters' statements that NMFS has substantially
overestimated takes are incorrect. As discussed in our 2021 final rule
response to the Associations' 2018 comments on this topic (86 FR 5322,
5347, January 19, 2021), NMFS used current scientific information and
state-of-the-art acoustic propagation and animal movement modeling to
reasonably estimate potential exposures to noise. With regard to the
acoustic exposure modeling, NMFS reiterates part of its 2021 response
to the 2018 comments, which remains applicable: the Associations'
comments do not specify which of the many data inputs are
``conservative'' or to what degree, nor do they recommend alternatives
to the choices that were meticulously documented in developing the
modeling.
As in their 2018 public comment letter, the Associations
inappropriately characterize statements from NMFS' notice of proposed
rulemaking as admissions of purposeful conservativeness. The
Associations refer to NMFS' description of the take numbers subject to
analysis for purposes of the negligible impact determinations in this
rule. In contrast to the 2018 proposed rule, for which NMFS used
modeling of one airgun array, for this final rule, NMFS considered
acoustic exposure modeling results from three different airgun arrays,
and stated simply that, for each species, the maximum take number
resulting from analysis of the three different arrays was subject to
evaluation as part of NMFS' negligible impact determinations. This
approach ensures that the potential takes of each species that could
occur from survey effort this final rule is designed to cover--surveys
that may involve various airgun arrays--are appropriately analyzed to
enable issuance of LOAs for those activities with reasonably accurate
take estimates.
The Associations also refer again to the 2017 Acoustic Exposure
Model Variable Analysis (Zeddies et al., 2017b) as being supportive of
their claims that NMFS' modeling is inappropriately conservative,
stating that the results show that ``alterations to only 4 or 5
variables have dramatic consequences that are the result of redundantly
applied precaution [. . .].'' The Associations incorrectly characterize
the results of the analysis, which investigated five factors:
<bullet> Airgun array size (including total volume, number of array
elements, element air pressure, array geometry and spacing) used in
source and propagation models;
<bullet> Acoustic threshold criteria and associated weighting used
to calculate exposures;
<bullet> Animal densities used for adjusting simulated computer
model exposures to potential real-world animal exposures;
<bullet> Natural aversive behaviors of marine mammals; and
<bullet> The addition of mitigative measures that lessen the
potential for animals' exposure to threshold levels of seismic sound.
The primary finding of the Zeddies et al. (2017b) analysis is that
use of NMFS' acoustic injury criteria (i.e., NMFS, 2016, 2018)
decreased predictions of injurious exposure. Thus, NMFS' 2018 proposed
rule had already incorporated the change with the most significant
impact on estimated take numbers.
We addressed the Associations' investigation of quantitative
consideration of animal aversion and mitigation effectiveness in
responses to comments provided in the 2021 final rule. In summary,
these factors were not quantified in the modeling because there is too
much inherent uncertainty regarding the effectiveness of detection-
based mitigation for these activities to support any reasonable
quantification of its effect in reducing injurious exposure, and there
is too little information regarding the likely level of onset and
degree of aversion to justify its use in the modeling via precise
quantitative control of animat movements (as compared to post-hoc
adjustment of the modeling results, as was done in the 2021 final rule
and carried forward here). Importantly, while aversion and mitigation
implementation are expected to reduce somewhat the modeled levels of
injurious exposure, they would not be expected to result in any
meaningful reduction in assumed exposures resulting in Level B
harassment, nor in total takes by harassment, as any averted injurious
(Level A harassment) takes would be appropriately changed to behavioral
disturbance (Level B harassment) takes. With regard to marine mammal
density information, NMFS has used in both the 2021 final rule and this
rule the best available scientific information.
NMFS previously responded to the Associations' comments that the
selected array (8,000 in\3\) is unrealistically large, resulting in an
overestimation of likely source levels and, therefore, size of the
sound field with which marine mammals would interact. We noted then our
agreement with the premise that use of a smaller airgun array volume
with lower source level would likely create a smaller ensonified area
resulting in fewer numbers of animals expected to exceed exposure
thresholds, but that selection of the representative array to be used
in the modeling was directed by the ITR applicant (i.e., BOEM). For the
2023 proposed rule, in reflection of prior comments from the
Associations and others, NMFS determined it appropriate to develop full
modeling results for analysis that would provide more scalable take
numbers suitable for the actual sound sources in use, and introduced
the alternative 4,130-in\3\ and 5,110-in\3\ airgun arrays. This
approach directly refutes the Associations' suggestion that NMFS has
not appropriately responded to public comments and made changes as
warranted.
With regard to the large number of other data inputs and/or choices
made in the modeling, the Associations do not specifically identify any
issue where they believe a meaningful data or process error was made in
the modeling. NMFS reiterates its conclusion that, while the modeling
required that a number of assumptions and choices be made by subject
matter experts, these are reasonable, scientifically acceptable
choices. These choices do not represent a series of ``overly
conservative, worst-case assumptions'' that, as the Associations state,
result in a ``compounding error yielding unrealistic calculations
lacking scientific basis.'' To the extent that the results of the
modeling may be conservative, they are the most credible, science-based
information available at this time.
NMFS reiterates its conclusion that the modeling effort
incorporated representative sound sources and projected survey
scenarios (based on the best available information obtained by BOEM, as
supplemented by NMFS to address additional airgun sizes that are
reasonably likely based on LOA applications to date--which alleviates
the primary source of conservativeness about which NMFS and the
Associations find agreement), physical and geological oceanographic
parameters at multiple locations within the GOM and during different
seasons, the best available information regarding marine mammal
distribution and
[[Page 31497]]
density, and available information regarding known behavioral patterns
of the affected species. Current scientific information and state-of-
the-art acoustic propagation and animal movement modeling were used to
reasonably estimate potential exposures to noise. The 2018 proposed
rule described all aspects of the modeling effort in significant
detail, including numerous investigations (test scenarios) designed by
the agencies to understand various model sensitivities and the effects
of certain choices on model results. Additionally, the 2023 proposed
rule described in detail all aspects of the modeling that were
different, while referring the reader to the 2018 proposed rule and
supplementary information for the bulk of the modeling effort, which
was unchanged. All relevant information was provided for public review,
on multiple occasions.
Because it remains relevant, we quote the MMC's 2018 public comment
on this topic: ``Complex sound propagation and animat modeling was used
to estimate the numbers of potential takes from various types of
geophysical surveys in the Gulf. NMFS received comments from industry
operators suggesting that the modeling results were overly conservative
[. . .]. However, the Commission has reviewed the modeling approach and
parameters used to estimate takes and believes they represent the best
available information regarding survey scenarios, sound sources,
physical and oceanographic conditions in the Gulf, and marine mammal
densities and behavior. As such, the Commission agrees with NMFS and
BOEM that the resulting take estimates were conservative but
reasonable, thereby minimizing the likelihood that actual takes would
be underestimated.''
Comment: The Associations describe potential mistakes in the take
numbers evaluated for this rule, noting that the total take numbers for
aggregated beaked whales across species and for blackfish across
species provided in Weirathmueller et al. (2022) exceed the values
provided by NMFS in table 6 of the 2023 proposed rule.
Response: NMFS clarifies that Appendix B of Weirathmueller et al.
(2022) provides essentially duplicate results for species that are
represented by the same density value. For example, Garrison et al.
(2023) \4\ provide generic (versus species-specific) density
information for beaked whales and blackfish. The results provided in
Weirathmueller et al. (2022) applied those same density values to
multiple species within a particular guild; thereby, duplicating
modeling results for, e.g., Cuvier's, Blainville's, and Gervais' beaked
whale. One can see that the resulting take numbers are the same for
Blainville's and Gervais' beaked whale, as these two species are
governed by the same assumed animal movement parameters in the animat
modeling. However, the results for Cuvier's beaked whale are slightly
different, resulting from the application of slightly different animal
movement parameters in the modeling. For purposes of providing an
estimate of total takes for the beaked whale guild, NMFS assumed the
larger set of values--as necessary to ensure that the potential takes
for the species with the largest values (in this case, Cuvier's beaked
whales) were appropriately analyzed. A similar situation exists for the
four species in the blackfish category, i.e., the four species are
represented together by a generic, guild density that encompasses all
four species. However, each of the four species were represented in the
animal movement modeling component by animats guided by species-
specific animal movement parameters. Thus, when the appropriate density
value was applied to scale the animat exposure estimates to real-world
exposure estimates, slightly different results were found across the
four species, but the total take number for the blackfish guild is
correctly represented through summing the take values for one of the
species. The take numbers provided in table 6 are correct; no error
exists.
---------------------------------------------------------------------------
\4\ At the time of publication of the 2023 proposed rule, no
technical reports associated with the updated density models had
been released to the public, and we cited the models (and density
outputs, which were publicly available online) as Garrison et al.
(2022) in that proposed rule. Associated reports (Rappucci et al.,
2023; Garrison et al., 2023) have since been released to the public.
In this final rule, references to the updated density models are
cited as Garrison et al. (2023).
---------------------------------------------------------------------------
Comment: Chevron states that the modeling performed in support of
the rule qualifies as a ``highly influential scientific assessment.''
Response: NMFS disagrees that the modeling constitutes a highly
influential scientific assessment. The Office of Management and
Budget's Final Information Quality Bulletin for Peer Review (70 FR
2664, January 14, 2005) defines a highly influential scientific
assessment as information whose dissemination could have a potential
impact of more than $500 million in any one year on either the public
or private sector or for which the dissemination is novel,
controversial, or precedent-setting, or has significant interagency
interest. Our Regulatory Impact Analysis (RIA) for the 2021 final rule,
which remains applicable, indicated that annual impacts are less than
$500 million. Moreover, similar approaches to acoustic exposure
modeling have been performed by numerous disparate entities for
multiple applications. In 2014, during a modeling workshop co-sponsored
by the American Petroleum Institute and International Association of
Geophysical Contractors, at least a half-dozen expert presenters
(representing private and governmental entities from both the United
States and Europe) discussed various available packages that function
much the same way as the modeling supporting this rule. Thus, there is
nothing novel, controversial, or precedent-setting about the modeling
described here, and the additional peer review requirements associated
with HISAs are not applicable.
Comment: The Associations encourage NMFS to consider employing what
they refer to as a ``pooled'' approach to authorizing take of species
that are rarely encountered in the GOM. The Associations suggest that
NMFS may authorize take via the suggested ``pool'' approach
generically, versus through an LOA issued to a specific applicant. This
authorized ``pool'' of take would then be drawn down as such take
occurs.
Response: NMFS appreciates the Associations' suggestion. We note
that, on February 17, 2022, the Associations proposed this concept to
NMFS as a potential solution to the errors in the rule. Instead, NMFS
determined it appropriate to pursue a corrective rulemaking. NMFS does
not believe the approach suggested by the Associations is necessary or
relevant following completion of this rule.
Comment: The Associations suggest that NMFS should develop an
appropriate ``scalar ratio'' for application to surveys of fewer than
20 days in duration.
Response: The scalar ratio employed by NMFS during implementation
of the ITR to date was developed in consideration of the relationship
between takes estimated for a full simulated 30-day survey, versus
those resulting from 24-hour results scaled up to the 30-day duration,
and is, therefore, suitable for use in better estimating the number of
individuals affected for surveys of longer duration (e.g., 20 days or
more). NMFS agrees with the Associations that it would be useful to
develop a suitable scalar ratio for surveys of shorter duration.
However, the Associations' comments on the topic suggest a
misunderstanding of the limitations under the rule on take
[[Page 31498]]
authorization. As rationale for the comment, they state that failure to
develop such a scalar ratio ``is a major problem because it will result
in an artificial and mathematically erroneous inflation of estimated
individual takes at the LOA level that may ultimately prevent
authorization of the amount of take contemplated'' in the rule.
However, for all surveys, NMFS authorizes through an LOA the
appropriate, unscaled estimated take number. Scaled values are only
used in the LOA-specific ``small numbers'' analysis to help inform an
assessment of how many individual marine mammals to which the estimated
instances of take might appropriately accrue. As such, lack of an
applicable scalar ratio for surveys of shorter duration means that NMFS
is analyzing overestimates of the numbers of individuals potentially
impacted (versus total instances of take) for purposes of the small
numbers analysis, but has no other effect on NMFS' ability to authorize
take under the rule. NMFS expects to consider development of the
recommended scalar ratio in the future, but has not to date undertaken
such an effort.
Comment: NRDC states that the density estimates used for Rice's
whale ``appear to omit most of the available science'' on Rice's whale
habitat, and notes that the density data are based on visual
observations made during large vessel surveys without incorporating
passive acoustic data.
Response: NMFS disagrees that the new Rice's whale density
estimates, which are based on spatial density models, omit most of the
available science on Rice's whale. These spatial density models are
based upon large vessel surveys conducted by NMFS' Southeast Fisheries
Science Center (SEFSC) between 2003 and 2019,\5\ including a mix of
broadscale line-transect surveys of shelf and oceanic waters, along
with directed surveys within the Rice's whale's northeastern GOM core
habitat (Rappucci et al., 2023; Garrison et al., 2023). Habitat
variables associated with the whale sightings during vessel surveys
from 2003-2019 were used to determine which variables are most
predictive of whale presence.
---------------------------------------------------------------------------
\5\ We note here that the 2023 proposed rule erroneously
referred to the period over which survey data were considered as
2003-2018. This range is correct for species other than Rice's
whale, for which surveys conducted in 2019 were incorporated.
---------------------------------------------------------------------------
Survey effort (kilometers of survey trackline) was partitioned into
segments within a grid of cells and matched to physical oceanographic
parameter values within each cell. All available oceanographic and
physiographic variables were included in the model selection for Rice's
whales. The selected model included water depth, chlorophyll-a
concentration, geostrophic velocity, bottom temperature, and bottom
salinity, and indicated that Rice's whale density was highest in waters
between 100-400 meter (m) depth with intermediate bottom temperatures
between 10-19 [deg]C and intermediate surface chlorophyll-a
concentrations, i.e., in areas along the outer continental shelf break
associated with higher productivity and upwelling of cooler bottom
water (Garrison et al., 2023). These predictions are consistent with
the information referenced by NRDC, i.e., passive acoustic detections
on the continental shelf break and current information regarding
habitat suitability. The web page for the habitat suitability study
referenced by NRDC indicates that the data were incorporated to updated
density models (see <a href="https://www.fisheries.noaa.gov/southeast/endangered-species-conservation/trophic-interactions-and-habitat-requirements-gulf-mexico">https://www.fisheries.noaa.gov/southeast/endangered-species-conservation/trophic-interactions-and-habitat-requirements-gulf-mexico</a> (``Combining environmental datasets with whale
sightings allows us to develop predictive habitat models that explain
what environmental features may be driving whale distribution.'')).
We agree that ideally, passive acoustic data could be incorporated
to the spatial density models to improve the model predictions.
However, incorporation of visual and acoustic data to spatial density
models remains cutting edge science, and such models have only rarely
been produced. NRDC refers to Roberts et al. (2016) as an example of
such modeling; however, Roberts et al. (2016) did not incorporate any
acoustic data to their models. The long-term cetacean density modeling
effort represented by reference to Roberts et al. (2016) is in fact a
good example of the difficulty of doing so. This U.S. Navy-funded
effort has been responsible for continually improved iterations of
spatial density models for cetaceans along the U.S. East Coast since
2015. However, to date, acoustic data have been incorporated only into
models for beaked whales and sperm whales (two species that are most
amenable to acoustic surveys and for which acoustic detections are most
important to understanding occurrence), and only in the most recently
updated model iterations. This required 7 years and a model version 7
for beaked whales and model version 8 for sperm whales (<a href="https://seamap.env.duke.edu/models/Duke/EC/">https://seamap.env.duke.edu/models/Duke/EC/</a>). Acoustic data have been used to
qualitatively verify density model predictions for certain mysticetes,
but have not been incorporated to date into any East Coast mysticete
density model. Efforts to evaluate the feasibility and utility of
combining visual and acoustic survey data in the GOM have only recently
been conducted as a pilot study (Frasier et al., 2021).
We note that the same areas in which the acoustic detections were
made are predicted by the spatial density model as being suitable
Rice's whale habitat (see <a href="https://seamap.env.duke.edu/models/SEFSC/GOM/">https://seamap.env.duke.edu/models/SEFSC/GOM/</a>
) and, in fact, density predictions within areas expected to provide
suitable habitat for Rice's whale increased compared with the
predictions provided by Roberts et al. (2016) (e.g., Rice's whale
density value in Zone 5, which includes areas of the central GOM where
acoustic detections were made, increased by 71 percent; see Appendix A
of Weirathmueller et al., 2022).
Comment: NRDC states that the only resource available to the public
regarding the revised density information was the density information
itself (available online for download) and that no associated report
was available for public review. NRDC goes on to state that marine
mammal density estimates ``are typically presented in publicly
available technical memoranda or technical reports, which set forth in
detail the authors' data sources, methods, quantitative results, and
limitations, with discussion of their application to particular
species,'' and suggests that failure to provide such a report may be a
violation of the APA. The MMC similarly recommends that NMFS provide to
the public ``marine mammal densities, associated [coefficients of
variation], and supporting documentation regarding how such estimates
were derived.'' Both NRDC and the MMC requested an additional 30-day
public comment period once the information is provided.
Response: The data and analyses supporting this final rule have
undergone appropriate pre-dissemination review for utility, integrity,
and objectivity, and have been determined to be in compliance with the
applicable information quality guidelines implementing the Information
Quality Act (section 515 of Pub. L. 106-554).
NMFS acknowledges that supporting technical reports related to the
marine mammal density data used in the exposure modeling informing this
rule were not publicly available at the time that NMFS' proposed rule
was released to the public for review. NMFS did not have discretion
over the timeline for release of supporting technical reports,
[[Page 31499]]
as BOEM is the primary funding agency for development of the updated
marine mammal density data. The reports have since been released
(Rappucci et al., 2023; Garrison et al., 2023) and are available online
at <a href="https://www.govinfo.gov/collection/boem">https://www.govinfo.gov/collection/boem</a>.
The NOAA Information Quality guidelines expressly address and allow
for the use of supporting information which cannot be disclosed. In
this case, the supporting information (i.e., the density data) was
publicly available. However, technical description regarding
development of that information had not been released, as described
above. The ``especially rigorous robustness checks'' called for in the
guidelines when proprietary models are used or when supporting
information cannot be disclosed had already been conducted by the model
authors, as described in the reports, and NMFS has conducted rigorous
robustness checks of the data used in support of this rule.
To determine the abundance and spatial distribution of marine
mammals in the GOM, NMFS' SEFSC conducts visual line transect surveys
aboard NOAA research vessels or aircraft, with survey effort designed
to support estimation of abundance for all marine mammals in the GOM.
Similar survey efforts and abundance estimation have been ongoing in
the GOM since the early 1990s and have been subject to both peer and
other public review on numerous occasions.
In addition to abundance, line transect survey data can be used to
develop habitat models that map animal density as a function of
environmental conditions. Historically, distance sampling methodology
(Buckland et al., 2001) has been applied to visual line-transect survey
data to estimate abundance within large geographic strata (e.g.,
Fulling et al., 2003; Mullin and Fulling, 2004; Palka, 2006). Design-
based surveys that apply such sampling techniques produce stratified
abundance estimates and do not provide information at appropriate
spatiotemporal scales for assessing environmental risk of a planned
survey. To address this issue of scale, efforts were developed to
relate animal observations and environmental correlates such as sea
surface temperature in order to develop predictive models used to
produce fine-scale maps of habitat suitability (e.g., Waring et al.,
2001; Hamazaki, 2002; Best et al., 2012). However, these studies
generally produce relative estimates that cannot be directly used to
quantify potential exposures of marine mammals to sound, for example. A
more recent approach known as density surface modeling, as described in
Roberts et al. (2016) and used by Garrison et al. (2023), couples
traditional distance sampling with multivariate regression modeling to
produce density maps predicted from fine-scale environmental covariates
(e.g., Becker et al., 2014, 2017, 2020; Forney et al., 2015).
In summary, the modeling effort follows accepted, state of the
science density modeling procedures (Rappucci et al., 2023; Garrison et
al., 2023), and habitat based density modeling in general is not novel,
controversial, or precedent-setting, as similar modeling has been
performed for various applications for over 10 years. There were no
novel assumptions or methodologies employed in development of the
models; the models simply make use of updated information regarding
marine mammal observations and associated habitat covariates. In
addition, ample opportunity was provided for public input and review of
the underlying scientific information and modeling efforts contained
herein (including by scientists, peer experts at other agencies, and
non-governmental organizations). NMFS has not failed to provide
information necessary for interested parties to comment meaningfully.
Predictions from the updated density models were publicly released
in July 2022, and we note that the authors of the previously best
available density models (Roberts et al., 2016), which NMFS used in
support of its 2021 final rule, independently determined that the
updated models represent the best available scientific data, stating
``As of October 2022, SEFSC and [the Duke Marine Geospatial Ecology
Lab] consider the Roberts et al., 2016 models obsolete and recommend
the [Garrison et al., 2023] models [. . .] be used instead.'' See
<a href="https://seamap.env.duke.edu/models/SEFSC/GOM/">https://seamap.env.duke.edu/models/SEFSC/GOM/</a>. NMFS similarly
determined that the updated density models represented the best
available scientific data and, accordingly, should be used in an
updated modeling effort.
We also note that it is not unusual for updated density information
to be released without supporting technical reports. The latest major
update to the Roberts et al. east coast cetacean density models
(affecting all modeled taxa) was released in June 2022 and, as the best
available science, including by virtue of providing increased quality
of information regarding the North Atlantic right whale, was used in
support of numerous regulatory decisions immediately upon release.
However, due to the Navy's priorities as the funding agency, no
associated documentation was released until June 2023. Notably, neither
NRDC nor the MMC (or any other member of the public) commented on the
lack of supporting documentation in any of the numerous regulatory
actions under the MMPA that were proposed for public review during that
interval.
Further, concerning the MMC's reference to the actual density
values and associated CVs used in the take estimation process, this
information was provided upon request during the public comment period
to both the MMC and NRDC as well as to the Associations. (We note that
the specific density values used in the prior modeling effort were
included in the comprehensive modeling report. As minimal new
information was associated with the current updated effort, the updated
values were not included in the brief modeling memorandum, but could be
duplicated by the public using available information.) None of the
aforementioned entities included any comments regarding the specific
density values and associated CVs used in the take estimation process
in their comment letters. NMFS does not agree that the recommendations
to allow for an additional 30-day comment period for the public to
review supplementary technical reports in advance of issuing the final
rule are warranted.
Comment: The Associations provide comments critical of NMFS' core
distribution area, noting the lack of additional sightings or tagging
data to support the expansion of the previously described core habitat
area to areas offshore of Mississippi and stating that ``The addition
of these buffers and extension of Rice's whale densities into the
buffers causes overestimates of the amount of potential Rice's whale
take. . . .''.
Response: Neither the core distribution area nor the core habitat
area factored into the process for estimating Rice's whale takes in any
way. (See the Estimated Take section for explanation of the take
estimation process for this rule.) However, NMFS did consider whether
additional mitigation was warranted under the LPAI standard in light of
the best available information, including information regarding the
core distribution area. Based on that evaluation, we concluded the
current mitigation meets the LPAI standard. (See the Mitigation section
for our LPAI analysis.)
Comment: The MMC recommends that NMFS require a closure to survey
[[Page 31500]]
activity of the portion of the Rice's whale core distribution area that
overlaps the area covered by the ITR.
Response: As discussed in the 2023 proposed rule, the description
of a core distribution area which, relative to the core habitat area
described in the 2018 proposed rule and 2021 final rule, expands
westward into waters off Mississippi and into the area of the specified
activity covered by this final rule, does not reflect new information
regarding documented Rice's whale occurrence. The core distribution
area reflects a more conservative approach to considering the data,
including the application of substantial buffer areas to account for
uncertainty. Rice's whales have not been visually observed in the small
portion (5 percent) of the core distribution area that overlaps the
geographic scope of the specified activity under this rule, and 76
percent of that small portion of the core distribution area that
overlaps the geographic scope of the specified activity under this rule
is shallower than 100 m water depth or deeper than 400 m. Please see
the Mitigation section for more detailed discussion.
In summary, there is no information supporting identification of
this area (i.e., the 5 percent of the core distribution area
overlapping the geographic scope of this rule) as being of particular
importance relative to Rice's whale habitat more broadly (i.e., GOM
waters between 100-400 m depth), and only 24 percent of this area
contains water depths 100-400 m. As a result of these considerations,
NMFS has determined that a restriction on survey activity within the
portion of the core distribution area that occurs within the scope of
the rule is not warranted, as the available information does not
support a conclusion that such a restriction would contribute
meaningfully to a reduction in adverse impacts to Rice's whales or
their habitat. The MMC offers no additional rationale for closing this
area to survey activity, other than that it is now within the
geographic scope of the rule (despite the absence of new data
supporting this change). As such, NMFS disagrees and does not adopt the
MMC's recommendation.
In addition, we note the MMC's statement in support of this
recommendation that ``[i]t is not clear from the information presented
by NMFS how much the increase in the numbers of takes is attributed to
geophysical surveys that are expected to occur in the expanded core
distribution area [. . .].'' As described in the 2023 proposed rule,
changes in take estimates for all species result from (1) correction of
BOEM's errors in calculating updated estimated take following its
revision of scope for the 2021 final rule; (2) revisions to species
definition files governing animat behavior during animal movement
modeling; and (3) new density information for all species other than
Fraser's dolphin and rough-toothed dolphin. In addition, for Rice's
whale only, propagation modeling of a new array specification produced
the greatest values for estimated instances of take.
The process for estimating take numbers did not involve placement
of projected survey effort in specific locations, such as the portion
of the core distribution area that overlaps the geographic scope of the
ITR. Instead, within each modeling zone, acoustic source and
propagation modeling was performed using zone-specific environmental
parameters, following which animal movement modeling results in zone-
specific exposure estimates for animats. These estimates were then
scaled to real-world values using zone-specific density estimates,
generating 24-hour exposure estimates that were then scaled to totals
based on zone-specific level of effort projections (see table 1). No
survey effort is specifically assumed to occur within the portion of
the core distribution area that overlaps the area within scope of the
ITR.
The MMC goes on to state that ``the year-round restriction on
geophysical surveys in the Rice's whale core distribution area was the
basis of NMFS's negligible impact determination for the final rule.''
This is incorrect. As one consideration in support of our negligible
impact determination for Rice's whales, we noted that no survey
activity would occur in the northeastern GOM core habitat area (please
see discussion provided in the Description of Marine Mammals in the
Area of the Specified Activities section regarding the distinction
between Rice's whale core habitat and the core distribution area
discussed herein). This was not the result of any restriction, but
rather, BOEM's removal of the GOMESA area from the scope of the rule.
Comment: BOEM challenges statements made in NMFS' 2023 proposed
rule regarding potential Rice's whale habitat contraction relative to
the historical range. The Associations echo these concerns. The
Associations also claim that NMFS has made erroneous statements with
regard to the potential impacts of the Deepwater Horizon (DWH) oil
spill on Rice's whales.
Response: BOEM acknowledges that it is possible Rice's whales were
historically more broadly distributed throughout the GOM, but suggests
that currently available information is insufficient to definitively
support such a conclusion. Passive acoustic recording devices have
detected Rice's whale calls at several sites along the continental
shelf break from Florida to Texas, and more recently in Mexican waters
(Rice et al., 2014; Soldevilla et al., 2022, 2024). Nonetheless, we
agree that the number of Rice's whales and the full extent to which
Rice's whales use waters outside of 100-400 meter depths in the GOM
remains unclear. Please see the Description of Marine Mammals in the
Area of the Specified Activities section of this rule for added
discussion regarding Rice's whale occurrence.
The Associations suggest NMFS has claimed that the Rice's whale
population has declined. NMFS made no such statement in the 2023
proposed rule. NMFS referenced the low population abundance of the
Rice's whale while citing modeling results relating to the
quantification of injury from the DWH spill. The Associations are
incorrect in stating that NMFS has made erroneous statements regarding
the modeling results concerning quantification of injury. NMFS refers
the Associations to the detailed discussion provided in the 2018
proposed rule, as well as to DWH NRDA Trustees (2016), which presents
the estimates of concern to the Associations (i.e., 48 percent of the
Rice's whale population potentially exposed to DWH oil, with 17 percent
killed). NMFS has neither mischaracterized nor engaged in speculation
about the findings regarding quantified injury due to the DWH spill.
Comment: NRDC comments that NMFS has not prescribed mitigation for
Rice's whales sufficient to meet the MMPA's LPAI standard, adding that
NMFS has not adequately considered mitigation of impacts to habitat in
its decision-making. In support, NRDC refers to new scientific
information since the 2021 final rule was published, including
investigations of Rice's whale habitat.
Response: NMFS disagrees with NRDC's comments regarding the
adequacy of mitigation for Rice's whales and their habitat. NMFS fully
considered the new information NRDC references (see the Mitigation
section of this final rule). In our view, these investigations (e.g.,
Kok et al., 2023; Kiszka et al., 2023; Soldevilla et al., 2022)
solidify NMFS' previous understanding of the importance of continental
slope waters between approximately 100-400 m water depth as Rice's
whale habitat. (We note this same area (i.e., continental shelf and
slope waters between the 100-400 m
[[Page 31501]]
isobaths) was recently included in NMFS' proposed rule to designate
Rice's whale critical habitat under the ESA (88 FR 47453, July 24,
2023)). The previously used spatial density model for Rice's whale
(Roberts et al., 2016) identified waters of approximately 100-400 m
depth on the continental slope throughout the GOM as potential habitat,
and the updated density model (which, as discussed previously,
incorporates new data on Rice's whale habitat associations) predictions
do not markedly differ (Garrison et al., 2023).
Perhaps the most important new information is the acoustic
detection of Rice's whales in areas along the shelf break in the
central and western GOM, which for the first time demonstrates year-
round Rice's whale occurrence in areas outside of the previously
identified core habitat. Soldevilla et al. (2022) detected Rice's whale
calls at 3 of 4 sites in the central GOM south of Louisiana. Year-round
detections occurred sporadically at two of the sites, with calls
detected on 6 and 16 percent of days when recordings were available,
respectively. Calls were detected on 1 percent of days at the 3rd site,
in February and April only.
Additional information regarding Rice's whale acoustic detections
has become available since publication of the 2023 proposed rule. A
subsequent study placed acoustic recorders in shelf break waters in the
same central GOM area, and added a location in the western GOM offshore
of Texas (Soldevilla et al., 2024). This new information provides
additional evidence of the regular occurrence of Rice's whales outside
the northeastern GOM, with Rice's whale calls recorded on 33 and 25
percent of days at the central and western GOM sites, respectively. As
in the prior study, calls were recorded throughout the year.
The rate of call detections throughout the year is considerably
higher in the eastern GOM than at the central GOM sites where calls
were most commonly detected, with at least 8.3 calls/hour among 4
eastern GOM sites over 110 deployment days (Rice et al., 2014) compared
to 0.3 calls/hour over the 299-day deployment at the central GOM site
where calls were detected most frequently during the Soldevilla et al.
(2022) study. During that study, approximately 2,000 total calls were
detected at the central site over 10 months, compared to more than
66,000 total detections at the eastern GOM deployment site over 11
months (approximately 30 times more calls detected at the eastern GOM
site) (Soldevilla et al., 2022). Similarly, Soldevilla et al. (2024)
reported detecting 0.2 calls/hour at the western GOM site off Texas
(1,694 detections over 8,547 hours of recording).
Caution should always be used when interpreting passive acoustic
detection results because call detection rates are not necessarily
correlated with the density or abundance of whales in a given area.
Several factors influence call detection rates, including the rate at
which whales call (which can vary by demographic group, individual,
time of year, etc.) and the range over which calls can be detected
(which is affected by auditory masking from competing noise sources,
site characteristics and other factors) (Erbe et al., 2016; Gibb et
al., 2018). Many of these variables remain undetermined for Rice's
whales in the GOM. Those uncertainties notwithstanding, results from
passive acoustic recordings, combined with the low number of confirmed
and suspected visual sightings of Rice's whales in the central and
western GOM (Barkaszi and Kelly, 2019; Rosel et al., 2021; Garrison et
al., 2023), suggest that density and abundance of Rice's whales is
likely lower in the central and western GOM than in the species' core
habitat area in the eastern GOM. More research is needed to answer key
questions about Rice's whale abundance, density, habitat use,
demography, and stock structure in the central and western GOM.
Regarding the suggestion that NMFS has not adequately considered
habitat in its consideration of mitigation, we disagree. Habitat value
is informed by marine mammal presence and use, and the available data
can support the consideration and discussion of impacts to (and
mitigation for) both marine mammals and their habitat simultaneously.
The discussion above clearly considers physical features that can drive
habitat use (e.g., depth), as well as detailed information related to
relative presence in the eastern versus the central and western GOM,
which is indicative of preferred habitat in the east. As stated in the
2021 final rule, because habitat value is informed by marine mammal
presence and use, in some cases, there may be overlap in measures for
the species or stock and for use of habitat. NRDC has not presented any
information that would suggest habitat we did not consider for
mitigation.
In summary, the newly available data related to marine mammal
presence and habitat were considered under the LPAI standard, and we
concluded additional mitigation for Rice's whale was not warranted
under that standard.
Comment: NRDC finds fault with NMFS' consideration of
practicability concerning possible closure of potential Rice's whale
habitat in the central and western GOM to future survey activity,
suggesting that NMFS' reference to analysis presented in its Regulatory
Impact Analysis (RIA) for the 2021 final rule is not relevant. NRDC
also suggests that NMFS must consider that OCSLA ``requires a balancing
between the development of offshore energy resources and the protection
of marine resources'' and that, based on the requirements of Executive
Order 13990, NMFS must consider the social cost of carbon in making its
determinations regarding practicability of mitigation.
Response: As was acknowledged in the 2023 proposed rule, the RIA
did not directly evaluate a potential closure of potentially suitable
habitat in the central and western GOM outside of the Rice's whale core
distribution area. However, we disagree that the RIA is not relevant to
our practicability analysis here. The RIA's assessment of potential
restrictions in the northeastern GOM provided a useful framework for
considering practicability relating to a broad closure of potential
Rice's whale habitat to future survey activity.
To bolster that discussion, we turned to the same sources of data
referenced in the RIA in analysis of potential closure areas considered
therein (see <a href="https://www.data.boem.gov/Main/Default.aspx">https://www.data.boem.gov/Main/Default.aspx</a>). While areas
of Rice's whale habitat (i.e., water depths of 100-400 m on the
continental shelf break) contain less oil and gas industry
infrastructure than do shallower, more mature waters, and have been
subject to less leasing activity than deeper waters with greater
expected potential reserves, they nonetheless host significant industry
activity. BOEM provides summary information by water depth bin,
including water depths of 201-400 m. Omitting information regarding
water depths of 100-200 m, the area overlaps 33 active leases, with 17
active platforms and over 1,200 approved applications to drill. In the
past 20 years, over 500 wells have been drilled in water depths of 100-
400 m. These data confirm that there is substantial oil and gas
industry activity in this area and, therefore, the inability to collect
new seismic data could affect oil and gas development given that oil
companies typically use targeted seismic to refine their geologic
analysis before drilling a well. In addition, year-round occurrence of
Rice's whales in waters 100-400 m deep precludes the use of seasonal
closures to minimize exposure of Rice's whales. Therefore, we analyze
the potential for a year-round closure, which exacerbates the potential
for effects on oil and gas
[[Page 31502]]
productivity in the GOM because operators have no ability to plan
around the closure. While the area is not as important to regional oil
and gas productivity as the prospective deepwater central GOM closure
analyzed in the RIA (as we acknowledged in the 2023 proposed rule), the
more area-specific data provided above continue to support NMFS'
previous conclusions, which we affirm here: (1) We are unable to
delineate specific areas of Rice's whale habitat in the central and
western GOM where restrictions on survey activity would be appropriate
because there is currently uncertainty about Rice's whale density,
abundance, habitat usage patterns and other factors in the central and
western GOM; and (2) there is high likelihood that closures or other
restrictions on survey activity in all waters of 100-400 m depth in the
central and western GOM would have significant economic impacts.
Finally, we note that despite NRDC's concerns, it does not recommend
any particular closure that it believes NMFS should evaluate.
Regarding NRDC's suggestions concerning OCSLA--a statute
administered by BOEM--NMFS' statutory obligations arise under the MMPA
(with associated requirements under the Endangered Species Act,
National Environmental Policy Act, and Administrative Procedure Act,
among others). NMFS has no statutory obligation relative to OCSLA.
Similarly, NMFS' obligations under the MMPA require that we prescribe
the means of effecting the LPAI on the affected species or stock and
their habitat, which we have done here. E.O. 13990 does not require
NMFS to consider the social cost of carbon in determining whether
potential mitigation requirements are practicable under the MMPA.
Comment: NRDC states that NMFS ``fails to consider mitigation
measures'' for Rice's whale, suggesting that NMFS consider: (1)
allowing some survey activities in the area, such as surveys undertaken
by leaseholders to develop their lease blocks, while prohibiting
others; (2) extending geographically vessel strike avoidance measures
``presently in effect for industry in the core habitat area''; and (3)
requiring use of ``lowest practicable source levels within the whales'
communication frequencies for activities taking place in the vicinity
of the whales' habitat.'' In a somewhat similar vein, the MMC
recommends that NMFS ``restrict speculative geophysical surveys from
occurring in waters in the 100- to 400-m depth range in the Central and
Western Planning Areas.''
Response: NRDC does not provide supporting detail regarding its
recommended mitigation requirements. As such, NMFS is unable to fully
evaluate the suggested measures.
Regarding the suggestion to allow some surveys but prohibit others,
section 101(a)(5)(A) of the MMPA requires NMFS to make a determination
that the take incidental to a ``specified activity'' will have a
negligible impact on the affected species or stocks of marine mammals,
and will not result in an unmitigable adverse impact on the
availability of marine mammals for taking for subsistence uses. NMFS'
implementing regulations require applicants to include in their request
a detailed description of the specified activity or class of activities
that can be expected to result in incidental taking of marine mammals.
50 CFR 216.104(a)(1). Thus, the ``specified activity'' for which
incidental take coverage is being sought under section 101(a)(5)(A) is
generally defined and described by the applicant. Here, BOEM is the
applicant for the ITR in support of industry operators, and we are
responding to the specified activity as described in that petition (and
making the necessary findings on that basis). BOEM's petition made no
distinction between surveys that may be speculative or otherwise fall
into a category of surveys that NRDC suggests should be prohibited, and
those that are not.
Moreover, NRDC does not describe any useful metric for determining
which surveys should be allowed, aside from vague reference to
``surveys undertaken by leaseholders to develop their lease blocks.''
The MMC similarly does not provide any useful definition of the
``speculative'' surveys it believes NMFS should prohibit, aside from
stating that it believes these are typically ``2D or similar surveys.''
No 2D surveys have been conducted in the GOM during the period of time
since the ITR became effective. During that time, NMFS has issued over
50 LOAs. Less than 10 of these were issued to what are sometimes
referred to as ``multi-client operators,'' or companies that conduct
surveys in order to acquire data that may be sold to one or more
development companies. Regardless of the small proportion of LOAs
issued to such companies, the surveys conducted under those LOAs are
not necessarily what the commenters may refer to as ``speculative,''
but instead may be designed to cover multiple lease areas and therefore
provide data to multiple leaseholders. The suggestions are not
sufficiently developed to allow for adequate consideration.
Regarding vessel strike avoidance measures, NRDC does not specify
to what measures it is referring. However, the ITR already contains a
suite of vessel strike avoidance measures that apply wherever survey
activity is occurring.
Finally, NRDC does not describe any useful scheme by which ``lowest
practicable source levels within the whales' communication
frequencies'' might be defined. Further, NMFS previously responded to a
similar, if more detailed, comment in its 2021 final rule (86 FR 5387,
January 19, 2021).
Comment: NRDC states that NMFS ``fails to reconsider prescribing
quieter alternatives to conventional seismic airguns, despite evidence
of the availability of such alternatives,'' and claims that NMFS has
not adequately analyzed the practicability of such a requirement.
Response: NMFS acknowledges that there are an increasing number of
sources that may reasonably be considered as environmentally preferable
to conventional airguns, including sources operating at lower
frequencies and without the high peak pressure output associated with
airguns. In fact, such sources have been used during certain surveys
conducted under NMFS-issued LOAs. However, imposing requirements to use
certain technologies, or prescribing the manner in which geophysical
survey data must be acquired, would exceed NMFS' authority under the
MMPA. Survey funders and operators define survey objectives and
methodologies, including which acoustic sources are used, on the basis
of data needs that are beyond NMFS' technical expertise to judge. NRDC
argues that specific mandates are not required, versus a generic ``best
available technology'' requirement, but offers no recommended metrics.
NMFS agrees that increased use of environmentally preferable sources is
an appropriate goal, but it would be more appropriate to continue
working with industry to incentivize use of such sources and techniques
rather than require them.
Comment: NRDC states that NMFS uses an ``arbitrary'' method to
convert area-specific risk scores into a ``basis for making Gulf-wide
negligible impact determinations.'' NRDC takes issue with NMFS' use of
the median of zone-specific risk ratings (for those zones including at
least 0.05 percent of GOM-wide abundance for a particular species),
suggesting that the application of this method inappropriately
minimizes findings of ``high'' to ``very high'' risk for certain
species in Zone 5, where there is a confluence of relatively
[[Page 31503]]
high levels of survey activity and high proportions of GOM-wide
abundance for some species, resulting in high take numbers. NRDC
expressed concern that using the median does not allow for appropriate
consideration of the importance of specific areas to a particular
species, i.e., that this approach ``smooths'' away granularity of the
risk assessment.
Response: We disagree with NRDC's comments on this topic, and note
that NRDC provided no alternative recommendation. On the contrary, this
approach explicitly incorporates considerations of the importance of a
particular area to a species, or the particular localized threats faced
by a species, through the zone-specific vulnerability assessment that
contributes to the overall risk rating. In addition, NMFS' approach is
specifically designed to retain considerations of zone-specific impacts
and vulnerability beyond simply the inclusion of the vulnerability
scoring. For example, an alternative approach to generating a GOM-wide
risk rating would be to employ a wholly different paradigm in which
aggregate GOM-wide vulnerability and severity scores are assessed,
versus taking a median value of zone-specific ratings. NMFS retained
the median value approach precisely because we believe that evaluating
risk for such a large and variable area (i.e., the entire U.S. GOM)
with species and activities that are each highly localized would
provide only a very general and less informative answer regarding risk.
The approach employed by NMFS highlights the fundamental importance of
the spatiotemporal intersection of animals and activity as the
fundamental driver in evaluating risk, while also allowing us to avoid
exactly the effect of concern to NRDC (blurring of localized scoring)
by avoiding the influence of areas where a particular species
essentially does not occur on the overall risk rating for that species.
NRDC is incorrect that use of the median value is inappropriate or
that it has ``no biological basis.'' We note that mean (or average)
values can be more heavily skewed by outliers with small sample size
than median values. Thus, we chose the median as a better descriptor of
central tendency, which is a more appropriate perspective for the risk
analysis. (We also rounded up values of .5 (e.g., median score of 3.5
would be rounded to a 4), a mathematically valid approach that builds
in a reasonable degree of conservatism.)
As we discussed in response to NRDC's public comment on the 2018
proposed rule (January 19, 2021, 86 FR 5322, 5359), one of the
fundamental values of the analytical framework is that it is structured
in a spatially explicit way that can be applied at multiple scales,
based on the scope of the action and the information available, to
inform an assessment of the risk associated with the activity (or suite
of activities). This allows one to generate overall risk ratings while
also evaluating risk on finer scales. In this case, severity ratings
were generated on the basis of seven different GOM zones, allowing an
understanding not only of the relative scenario-specific risk across
the entire GOM, as is demanded for this analysis, but also to better
understand the particular zones where risk may be relatively high
(depending on actual future survey effort) and what part of the stock's
range may be subject to relatively high risk.
NRDC cites the Expert Working Group (EWG) Report in support of its
comment, stating it was ``[telling]'' that ``the [EWG] Report did not
contrive a Gulf-wide risk assessment'' and that ``doing so would have
belied the very different purpose underlying its design: a relative
risk assessment across multiple species and geographies.'' Although the
initial EWG report (Southall et al., 2017) made available for public
review of the framework concept did not derive GOM-wide risk ratings,
the EWG did so in a later draft report that NMFS adopted in producing
the risk evaluation presented in its 2021 final rule.
NRDC continues to suggest (as it did in its 2018 comment letter)
that the risk ratings are the primary or even sole basis for NMFS'
negligible impact determinations, and repeats the assertion that NMFS
has erroneously used the relativistic assessment presented in the EWG
report as the basis for the negligible impact determination, thereby
incorrectly applying the EWG report as though it evaluated absolute
risk. These claims are incorrect. We reiterate our 2021 response to
NRDC's previous comments on these topics (January 19, 2021, 86 FR 5322,
5359): the EWG analysis is an important component of the negligible
impact analysis, but is not the sole basis for our determination. While
the EWG analysis comprehensively considered the spatial and temporal
overlay of the activities and the marine mammals in the GOM, as well as
the number of takes predicted by the described modeling, there are
details about the nature of any ``take'' anticipated to result from
these activities that were not considered directly in the EWG analysis
and which warrant explicit consideration in the negligible impact
analysis. Accordingly, NMFS' analysis considers the results of the EWG
analysis, the effects of the required mitigation, and the nature and
context of the takes that are predicted to occur. NMFS' analysis also
explicitly considers the effects of predicted Level A harassment,
duration of Level B harassment events, and impacts to marine mammal
habitat, which respectively were not integrated into or included in the
EWG risk ratings. These components of the full analysis, along with any
germane species or stock-specific information, are integrated and
summarized for each species or stock in the Species and Stock-specific
Negligible Impact Analysis Summaries section of the negligible impact
analysis.
While the EWG framework produces relativistic risk ratings, its
components consist of absolute concepts, some of which are also
absolutely quantified (e.g., whether the specified activity area
contains greater than 30 percent of total region-wide estimated
population, between 30 and 15 percent, between 15 and 5 percent, or
less than 5 percent). Further, NMFS provided substantive input into the
scoring used in implementing the EWG framework for the GOM, to ensure
that the categories associated with different scores, the scores
themselves, and the weight of the scores within the overall risk rating
all reflected meaningful biological, activity, or environmental
distinctions that would appropriately inform the negligible impact
analysis. Accordingly, and as intended, we used our understanding of
the EWG framework and applied professional judgment to interpret the
relativistic results of the EWG analysis appropriately into the larger
negligible impact analysis, with the other factors discussed above, to
make the necessary findings specific to the effects of the total taking
on the affected species and stocks.
Comment: NRDC describes the risk assessment results for Rice's
whale over time (i.e., across NMFS' 2018 proposed rule, 2021 final
rule, and 2023 proposed rule) as inconsistent, particularly in Zone 5,
suggesting that there could be some unexplained error at play.
Response: NMFS acknowledges that the risk ratings for the Rice's
whale/Bryde's whale in Zone 5 have changed compared with the original
analysis presented in NMFS' 2018 proposed rule. In that analysis, Zone
5 risk was assessed as ``very high'' for the then-named Bryde's whale
across all evaluated scenarios. Assessed risk was reduced to ``low''
for the species in Zone 5 in NMFS' 2021 final rule, and this rating
remained consistent in NMFS' 2023 proposed rule. This change is
explained by the accompanying take
[[Page 31504]]
estimates in each of the three analyses: in the 2018 proposed rule, the
mean annual take number across scenarios for the species was 462, with
Zone 5 severity rankings ranging from high to very high. Following
revision of the analysis reflecting the erroneous take numbers
estimated by BOEM due to its removal of the GOMESA area, the mean
annual take number declined to 8. It is no surprise, then, that the
associated risk ratings changed from ``very high'' to ``low.'' In NMFS'
2023 proposed rule, following correction of the estimated take numbers,
but inclusive of BOEM's removal of the GOMESA area, the mean annual
take number increased to 26 and, accordingly, the risk ratings remained
low. The risk ratings assessed for Rice's whale across these analyses
simply reflect the underlying take estimates and, therefore, the
associated severity scoring. No error has been made.
Comment: The MMC recommends that NMFS provide an update on progress
by LOA-holders or their representative(s) toward completing and making
publicly available the synthesis report of all activities that were
conducted by LOA-holders during the first year of the reporting period
for the final rule.
Response: The report is complete and available online at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>.
Comment: The MMC reiterates its previous recommendation that NMFS
and BOEM establish a GOM scientific advisory group, composed of agency
and industry representatives and independent scientists, to assist in
the review of data collected to date and to identify and prioritize
monitoring needs and hypothesis-driven research projects to better
understand the short- and long-term effects of geophysical surveys on
marine mammals in GOM.
Response: NMFS reiterates its previous response to this
recommendation. NMFS would be willing to explore with the MMC the
appropriate mechanisms for convening such a group, including
consideration of the MMC's authorities under the MMPA. However, NMFS
disagrees that responsibility to establish such a group is either a
requirement of the MMPA, or warranted as a condition of promulgating
this rule.
Description of Marine Mammals in the Area of the Specified Activities
Table 2 lists all species with expected potential for occurrence in
the GOM and summarizes information related to the population or stock,
including potential biological removal (PBR). PBR, defined by the MMPA
as the maximum number of animals, not including natural mortalities,
that may be removed from a marine mammal stock while allowing that
stock to reach or maintain its optimum sustainable population, is
considered in concert with known sources of ongoing anthropogenic
mortality (as described in NMFS' stock assessment reports (SAR)). For
status of species, we provide information regarding U.S. regulatory
status under the MMPA and Endangered Species Act (ESA). The affected
species and stocks have not changed from those described in the notice
of issuance of the 2021 rule. We incorporate information newly
available since that rule, including updated information from NMFS'
SARs, but do not otherwise repeat discussion provided in this section
of the 2018 proposed rule and 2021 final rule.
In some cases, species are treated as guilds (as was the case for
the analysis conducted in support of the 2021 ITR). In general
ecological terms, a guild is a group of species that have similar
requirements and play a similar role within a community. However, for
purposes of stock assessment or abundance prediction, certain species
may be treated together as a guild because they are difficult to
distinguish visually and many observations are ambiguous. For example,
NMFS' GOM SARs assess stocks of Mesoplodon spp. and Kogia spp. as
guilds. As was the case for the 2021 final rule, we consider beaked
whales and Kogia spp. as guilds. In this rule, reference to ``beaked
whales'' includes the Cuvier's, Blainville's, and Gervais beaked
whales, and reference to ``Kogia spp.'' includes both the dwarf and
pygmy sperm whale.
The use of guilds in the 2021 final rule followed the best
available density information at the time (i.e., Roberts et al., 2016).
Subsequently, updated density information became available for all
species except for Fraser's dolphin and rough-toothed dolphin (Garrison
et al., 2023). The updated density models retain the treatment of
beaked whales and Kogia spp. as guilds and have additionally
consolidated 4 species into an undifferentiated blackfish guild. These
species include the melon-headed whale, false killer whale, pygmy
killer whale, and killer whale. The model authors determined that, for
this group of species, there were insufficient sightings of any
individual species to generate a species-specific model (Garrison et
al., 2023). Therefore, reference to blackfish hereafter includes the
melon-headed whale, false killer whale, pygmy killer whale, and killer
whale.\6\
---------------------------------------------------------------------------
\6\ NMFS' 2021 final rule provided take estimates separately for
the melon-headed whale, false killer whale, pygmy killer whale, and
killer whale. This rule provides a single take estimate for those
four species grouped together as the ``blackfish.'' This change in
approach reflects the best available scientific information, i.e.,
updated density information (Garrison et al., 2023). These species
are encountered only occasionally during any given vessel survey,
and these relatively infrequent encounters make it difficult to fit
species-specific detection and habitat models. Roberts et al. (2016)
fit species-specific models based on survey data from 1992-2009,
including 29, 19, 27, and 16 sightings, respectively, of these
species. For each of these models, the authors detail analyses and
decisions relevant to model development, as well as notes of caution
regarding use of the models given the associated uncertainty
resulting from development of a model based on few sightings. The
Garrison et al. (2023) models are based on survey data from 2003-
2019. Notably, surveys conducted after 2009 were conducted in
``passing'' mode, where the ship did not deviate from the trackline
to approach and verify species identifications for detected marine
mammal groups, resulting in an increase in observed marine mammal
groups that could not be identified to species. As a result of these
factors, the model authors determined it appropriate to develop a
single spatial model based on sightings of unidentified blackfish,
in addition to the relatively few sightings where species
identification could be confirmed.
---------------------------------------------------------------------------
Twenty-one species (with 24 managed stocks) have the potential to
co-occur with the prospective survey activities. For detailed
discussion of these species, please see the 2018 proposed rule. In
addition, the West Indian manatee (Trichechus manatus latirostris) may
be found in coastal waters of the GOM. However, manatees are managed by
the U.S. Fish and Wildlife Service and are not considered further in
this document. All managed stocks in this region are assessed in NMFS'
U.S. Atlantic SARs.
All values presented in table 2 are the most recent available at
the time the analyses for this notice were completed, including
information presented in NMFS' 2022 SARs (the most recent SARs
available at the time of publication) (available online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports</a>).
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In table 2 above, we report two sets of abundance estimates: those
from NMFS' SARs and those predicted by habitat-based cetacean density
models. Please see footnote 3 of table 2 for more detail. NMFS' SAR
estimates are typically generated from the most recent shipboard and/or
aerial surveys conducted. GOM oceanography is dynamic, and the spatial
scale of the GOM is small relative to the ability of most cetacean
species to travel. U.S. waters only comprise about 40 percent of the
entire GOM, and 65 percent of GOM oceanic waters are south of the U.S.
EEZ. Studies based on abundance and distribution surveys restricted to
U.S. waters are unable to detect temporal shifts in distribution beyond
U.S. waters that might account for any changes in abundance within U.S.
waters. NMFS' SAR estimates also in some cases do not incorporate
correction for detection bias. Therefore, for cryptic or long-diving
species (e.g., beaked whales, Kogia spp., sperm whales), they should
generally be considered underestimates (see footnotes 6 and 8 of table
2).
The model-based abundance estimates represent the output of
predictive models derived from multi-year observations and associated
environmental parameters and which incorporate corrections for
detection bias (the same models and data from which the density
estimates are derived). Incorporating more data over multiple years of
observation can yield different results in either direction, as the
result is not as readily influenced by fine-scale shifts in species
habitat preferences or by the absence of a species in the study area
during a given year. NMFS' SAR abundance estimates show substantial
year-to-year variability in some cases. Incorporation of correction for
detection bias should systematically result in greater abundance
predictions. For these reasons, the model-based estimates are generally
more realistic and, for the purposes of assessing estimated exposures
relative to abundance--used in this case to understand the scale of the
predicted takes compared to the population--NMFS generally believes
that the model-based abundance predictions are the best available
information and most appropriate because they were used to generate the
exposure estimates and therefore, provide the most relevant comparison.
NMFS' 2021 final rule provided take estimates separately for the
melon-headed whale, false killer whale, pygmy killer whale, and killer
whale. This rule provides a single take estimate for those four species
grouped together as the blackfish. This approach was dictated by the
best available science. The model authors determined it necessary to
aggregate the few sightings data available for each of the four species
with sightings data that could not be resolved to the species level in
order to develop a density model, as there were not sufficient
confirmed sightings of individual species to create individual spatial
models (Garrison et al., 2023). Further, the model authors advised that
any attempt to parse the results to species would be fraught with
complicated assumptions and limited data, and that there is no readily
available way to do so in a scientifically defensible manner. Previous
estimates (Roberts et al., 2016) were based on older data (data range
1992-2009 versus 2003-2019), and the updated models notably include
post-DWH oil spill survey data and, for the first time, winter survey
data. Nonetheless, interested members of the public may review NMFS'
2018 proposed rule and supporting documentation, which assumed slightly
greater activity levels and larger take numbers before the GOMESA area
was removed and still preliminarily determined a negligible impact on
all 4 species comprising the blackfish group.
NMFS does not have sufficient information to support apportioning
the blackfish takes to the constituent species, but we note that the
sum of annual average evaluated take for the 4 species in the 2021
final rule is 64,742, while the new annual average take estimate for
blackfish (using the updated density information) is 55,441.
NMFS' ability to issue LOAs under the 2021 rule to date has been
limited specifically with regard to killer whales, because BOEM's error
most severely affected killer whale take numbers. (Evaluated Rice's
whale takes were similarly affected, but were generally not implicated
in LOA requests based on the location of planned surveys.) Effects to
killer whales from the specified activity have not presented particular
concern in a negligible impact context, even considering the original
take numbers evaluated in NMFS' 2018 proposed rule (annual average take
of 1,160), which produced overall scenario-specific risk ratings of low
to moderate. Evaluated risk is similar across the 2018 proposed rule
and this rule.
Further, we note that we make a conservative assumption in this
rule in the application of the risk assessment framework to blackfish.
Risk is a product of severity and vulnerability. While severity is
based on density and abundance and is, therefore, reflective of the new
density information, vulnerability is based on species-specific factors
and is different for the four species. We applied the highest
vulnerability score of the four to combine with the severity to get the
overall risk rating for the group. Please see Negligible Impact
Analysis and Determinations for additional discussion.
As part of our analyses for incidental take rules, we consider any
known areas of importance as marine mammal habitat. We also consider
other relevant information, such as unusual mortality events (UME) and
the 2010 DWH oil
[[Page 31508]]
spill. The 2018 proposed rule provided detailed discussion of important
marine mammal habitat, relevant UMEs, and of the DWH oil spill. The
2021 final rule updated those discussions as necessary. That
information is part of the baseline for our analyses for this final
rule. There have been no new UMEs, or new information regarding the
UMEs discussed in the prior notices. Similarly, there is no new
information regarding the DWH oil spill. However, estimates of annual
mortality for many stocks over the period 2014-2018 now include
mortality attributed to the effects of the DWH oil spill (see table 2)
(Hayes et al., 2021), and these mortality estimates are considered as
part of the environmental baseline.
Habitat. Important habitat areas may include areas of known
importance for reproduction, feeding, or migration, or areas where
small and resident populations are known to occur. They may have
independent regulatory status such as designated critical habitat for
ESA-listed species (as defined by section 3 of the ESA) or be
identified through other means (e.g., recognized Biologically Important
Areas (BIA)).
As noted above in table 2, the former GOM Bryde's whale has been
described as a new species, Rice's whale (Rosel et al., 2021). No
critical habitat has yet been designated for the species, though a
proposed rule was published (88 FR 47453, July 24, 2023). The proposal
references the same supporting information discussed herein, and draws
similar conclusions in suggesting that GOM continental slope waters
between 100-400 m water depth be designated as critical habitat. In
addition, a BIA has been recognized since 2015 (LaBrecque et al.,
2015). This year-round BIA was discussed in the 2018 proposed rule and
2021 final rule, and we do not repeat the description of the 2015 BIA.
NOAA's ESA status review of the former GOM Bryde's whale (Rosel et
al., 2016) expanded the 2015 BIA description by stating that, due to
the depth of some sightings, the area is appropriately defined to the
400-m isobath and westward to Mobile Bay, Alabama, in order to provide
some buffer around the deeper sightings and to include all sightings in
the northeastern GOM. Based on the description provided by the status
review (Rosel et al., 2016), our 2018 proposed rule considered a Rice's
whale ``core habitat area'' between the 100- and 400-m isobaths, from
87.5[deg] W to 27.5[deg] N (83 FR 29212, August 21, 2018), in order to
appropriately encompass Rice's whale sightings at the time. In
addition, the area largely covered the home range (i.e., 95 percent of
predicted abundance) predicted by Roberts et al. (2016).
NMFS SEFSC subsequently developed a description of what is referred
to as a Rice's whale ``core distribution area'' \7\ (<a href="https://www.fisheries.noaa.gov/resource/map/rices-whale-core-distribution-area-map-gis-data">https://www.fisheries.noaa.gov/resource/map/rices-whale-core-distribution-area-map-gis-data</a>) (see Figures 3 and 4) (Rosel and Garrison, 2022). The
authors state that the core distribution area description is based on
visual sightings and tag data, and does not imply knowledge of habitat
preferences (Rosel and Garrison, 2022). A description of the core
distribution area and associated methodology was provided in the 2023
proposed rule (88 FR 916, 924-925, January 5, 2023). In summary, that
process involved the addition of buffers meant to address uncertainty
regarding whale locations and possible movements from those locations
to a polygon encompassing all confirmed Rice's whale visual
observations and location data from two tagged whales. The
incorporation of this approach to address uncertainty is what
differentiates the ``core habitat area'' discussed in the previous
paragraph, considered in the 2018 proposed rule and 2021 final rule,
from the ``core distribution area.'' The core distribution area does
not reflect new sightings data or other information relative to the
basis for the core habitat area. However, whereas the ``core habitat
area'' was located entirely within the GOMESA area removed from the
geographic scope of the specified activity for the 2021 final rule (and
therefore no longer relevant for consideration in prescribing
mitigation), the buffer portion of the ``core distribution area''
results in a small overlap with the geographic scope of the specified
activity (5 percent) and is therefore appropriate for consideration.
---------------------------------------------------------------------------
\7\ The 2023 proposed rule retained the ``core habitat area''
terminology when describing the core distribution area, for
continuity with the 2021 rule, but this final rule reverts to
preserving the different terminologies associated for each.
---------------------------------------------------------------------------
Our knowledge of Rice's whale distribution is based on a
combination of historic and contemporary sightings, passive acoustic
detections, and spatial modeling. The evidence collected from these
methods indicates that Rice's whales occupy waters along the
continental shelf and slope and adjacent waters throughout the U.S.
GOM, and in particular, waters between 100 and 400 m deep. The widest
swath of habitat occurs in the species' core distribution area in the
northeastern GOM, south and west of Alabama and Florida. However, a
contiguous strip of habitat also extends south of the core distribution
area toward the Florida Keys, and westward along the continental shelf
and slope offshore of Mississippi, Louisiana, and Texas (Garrison et
al., 2023). PAM recordings have been especially valuable for confirming
the species' year-round presence in the central and western GOM
(Soldevilla et al., 2022, 2024), helping to offset the limited visual
survey effort in those locations. The shallowest and deepest waters
where Rice's whales have been confirmed visually to date are 117 m and
408 m, respectively, but Rice's whales may use waters that are deeper
or shallower than those values at times. Historic whaling records
indicate Rice's whales occurred more broadly throughout the GOM
historically (Reeves et al., 2011), and unconfirmed sightings from
protected species observers have occurred at a wider range of locations
and depths (Barkaszi and Kelley, 2018, 2024).
Potential Effects of the Specified Activities on Marine Mammals and
Their Habitat
In NMFS' 2018 proposed rule (83 FR 29212, June 22, 2018), this
section included a comprehensive summary and discussion of the ways
that components of the specified activity may impact marine mammals and
their habitat, including general background information on sound and
specific discussion of potential effects to marine mammals from noise
produced through use of airgun arrays. NMFS provided a description of
the ways marine mammals may be affected by the same activities
considered herein, including sensory impairment (permanent and
temporary threshold shifts and acoustic masking), physiological
responses (particularly stress responses), behavioral disturbance, or
habitat effects, as well as of the potential for serious injury or
mortality. The 2021 final rule (86 FR 5322, January 19, 2021) provided
updates to the discussion of potential impacts, as well as
significantly expanded discussion of certain issues (e.g., potential
effects to habitat, including prey, and the potential for stranding
events to occur) in the ``Comments and Responses'' section of that
notice. These prior notices also provided discussion of marine mammal
hearing and detailed background discussion of active acoustic sources
and related acoustic terminology used herein. We have reviewed new
information available since the 2021 final rule was issued. Having
considered this information, we have determined that there is no new
information that substantively affects
[[Page 31509]]
our analysis of potential impacts on marine mammals and their habitat
that appeared in the 2018 proposed and 2021 final rules, all of which
remains applicable and valid for our assessment of the effects of the
specified activities during the original 5-year period that is the
subject of this rule. We incorporate by reference that information and
do not repeat the information here, instead referring the reader to the
2018 proposed rule and 2021 final rule.
The Estimated Take section later in this document includes a
quantitative analysis of the number of individuals that are expected to
be taken by the specified activity. The Negligible Impact Analysis and
Determinations section includes an analysis of how these activities
will impact marine mammals and considers the content of this section,
the Estimated Take section, and the Mitigation section, to draw
conclusions regarding the likely impacts of these activities on the
reproductive success or survivorship of individuals and from that on
the affected marine mammal populations.
Estimated Take
This section provides an estimate of the numbers and type of
incidental takes that may be expected to occur under the specified
activity, which informs NMFS' negligible impact determinations.
Realized incidental takes would be determined by the actual levels of
activity at specific times and places that occur under any issued LOAs
and by the actual acoustic source used. While the methodology and
modeling for estimating take remains identical to that originally
described in the 2018 proposed and 2021 final rules, updated species
density values have been used, and take estimates are available for
three different airgun array configurations. The highest modeled
estimated take (annual and 5-year total) for each species is analyzed
for the negligible impact analysis.
Except with respect to certain activities not pertinent here,
section 3(18) of the MMPA defines ``harassment'' as: any act of
pursuit, torment, or annoyance which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment). As with the 2021 final
rule, harassment is the only type of take expected to result from these
activities. It is unlikely that lethal takes would occur even in the
absence of the mitigation and monitoring measures, and no such takes
are anticipated or will be authorized.
Anticipated takes would primarily be by Level B harassment, as use
of the described acoustic sources, particularly airgun arrays, is
likely to disrupt behavioral patterns of marine mammals upon exposure
to sound at certain levels. There is also some potential for auditory
injury (Level A harassment) to result for low- and high-frequency
species due to the size of the predicted auditory injury zones for
those species, though none is predicted to occur for Rice's whales (the
only low-frequency cetacean in the GOM). NMFS does not expect auditory
injury to occur for mid-frequency species. See discussion provided in
the 2018 notice of proposed rulemaking (83 FR 29212, June 22, 2018) and
in responses to public comments provided in the notice of issuance for
the 2021 final rule (86 FR 5322, January 19, 2021).
Below, we summarize how the take that may be authorized was
estimated using acoustic thresholds, sound field modeling, and marine
mammal density data. Detailed discussion of all facets of the take
estimation process was provided in the 2018 notice of proposed
rulemaking (83 FR 29212, June 22, 2018), which is incorporated by
reference here, as it was into the 2021 final rule, as most aspects of
the modeling have not changed; any aspects of the modeling that have
changed are noted below and in Weirathmueller et al. (2022). Please see
that 2018 proposed rule notice, and associated companion documents
available on NMFS' website, for additional detail. A summary overview
of the take estimation process, as well as full discussion of new
information related to the development of estimated take numbers, is
provided below.
Acoustic Thresholds
NMFS uses acoustic thresholds that identify the received level of
underwater sound above which exposed marine mammals generally would be
reasonably expected to exhibit disruption of behavioral patterns (Level
B harassment) or to incur permanent threshold shift (PTS) of some
degree (Level A harassment). Acoustic criteria used herein were
described in detail in the preceding notices associated with the 2018
proposed rule and 2021 final rule; that discussion is not repeated as
no changes have been made to the relevant acoustic criteria. See tables
3 and 4.
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Acoustic Exposure Modeling
Zeddies et al. (2015, 2017a) provided estimates of the annual
marine mammal acoustic exposures exceeding the aforementioned criteria
caused by sounds from geophysical survey activity in the GOM for 10
years of notional activity levels, using 8,000-in\3\ airguns and other
sources, as well as full detail regarding the original acoustic
exposure modeling conducted in support of BOEM's 2016 petition and
NMFS' subsequent analysis in support of the 2021 final ITR. Zeddies et
al. (2017b) provided information regarding source and propagation
modeling related to the 4,130-in\3\ airgun array, and Weirathmueller et
al. (2022) provide detail regarding the new modeling performed for the
5,110-in\3\ airgun array. Detailed discussion of the original modeling
effort was provided in the 2018 notice of proposed rulemaking (83 FR
29212, June 22, 2018), and in responses to public comments provided in
the notice of issuance for the final rule (86 FR 5322, January 19,
2021). For full details of the modeling effort, see the reports
(available online at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>) and review discussion provided in those prior Federal
Register notices.
All acoustic exposure modeling, including source and propagation
modeling, was redone in support of this final rule to address the
additional airgun array configurations and the new data on marine
mammal density and species definition files, as described below in this
section. However, all aspects of the modeling (including source,
propagation, and animal movement modeling) are the same as described in
Zeddies et al. (2015, 2017a, 2017b) and discussed in previous Federal
Register notices associated with the ITR. We do not repeat discussion
of those aspects of the modeling, but refer the reader to those
documents.
Differences from the modeling and modeling products described in
previous notices associated with this ITR are limited to source and
propagation modeling of the new 5,110-in\3\ array configuration, which
was performed using the same procedures as were used for the previous
8,000- and 4,130-in\3\ array configurations, and two new data inputs:
(1) updated marine mammal density information (Garrison et al., 2023)
and (2) revised species definition files. The latter information
consists of behavioral parameters (e.g., depth, travel rate, dive
profile) for each species that govern simulated animal (animat)
movement within the movement model (Weirathmueller et al., 2022). These
files are reviewed at the start of all new and reopened modeling
efforts, and are updated as necessary according to the most recent
literature. NMFS previously evaluated full acoustic exposure modeling
results only for the 8,000-in\3\ airgun array (only demonstration
results for 6 species were provided in Zeddies et al. (2017b) for the
4,130-in\3\ array configuration), but is now able to evaluate full
results for all three array configurations; thereby, providing for
greater flexibility and utility in representing actual acoustic sources
planned for use during consideration of LOA requests.
Marine Mammal Density Information--Since the 2021 final rule went
into effect, new habitat-based cetacean density models have been
produced by NMFS' Southeast Fisheries Science Center (Garrison et al.,
2023). These models incorporate newer survey data from 2017-18
including, notably, data from survey effort conducted during winter.
Inclusion of winter data allows for increased temporal resolution of
model predictions. These are the first density models that incorporate
survey data collected after the DWH oil spill. New models were produced
for all taxa other than Fraser's dolphin and rough-toothed dolphin, as
the model authors determined that there were too few detections of
these species to support model development. Therefore, we continue to
rely on the Roberts et al. (2016) models for these two species.
For species occurring in oceanic waters, the updated density models
are based upon data collected during vessel surveys conducted in 2003-
04, 2009, and 2017-18 (and including surveys conducted in 2019 for
Rice's whale). Survey effort was generally conducted in a survey region
bounded by the shelf break (approximately the 200-m isobath) to the
north and the boundary of the U.S. EEZ to the south. Separate models
were created for species occurring in shelf waters (Atlantic spotted
dolphin and bottlenose dolphin) based on seasonal aerial surveys
conducted in 2011-12 and 2017-18. Based on water depth, the shelf
models were used to predict acoustic exposures for these two species in
Zones 2 and 3, and the oceanic models were used to predict exposures in
Zones 4-7.
As discussed above, the updated density modeling effort retains the
previous approach of treating beaked whales and Kogia spp. as guilds,
as sightings of these species are typically difficult to resolve to the
species level. In addition, the model authors determined there to be
too few sightings and/or too few sightings resolved to species level
for the melon-headed whale, false killer whale, pygmy killer whale, and
killer whale to produce individual species models. Instead, a single
blackfish model was developed to produce guild-level predictions for
these species (Garrison et al., 2023).
[[Page 31511]]
Take Estimates
Exposure estimates above Level A and Level B harassment criteria,
originally developed by Zeddies et al. (2015, 2017a, 2017b) and updated
by Weirathmueller et al. (2022) in association with the activity
projections for the various annual effort scenarios, were generated
based on the specific modeling scenarios (including source and survey
geometry), i.e., 2D survey (1 x source array), 3D NAZ survey (2 x
source array), 3D WAZ survey (4 x source array), coil survey (4 x
source array).
Level A Harassment--Here, we summarize acoustic exposure modeling
results related to Level A harassment. For more detailed discussion,
please see the 2018 Federal Register notice for the proposed rule and
responses to public comment provided in the 2021 Federal Register
notice for the final rule. Overall, there is a low likelihood of take
by Level A harassment for any species, though the degree of this low
likelihood is primarily influenced by the specific hearing group. For
mid- and high-frequency cetaceans, potential auditory injury would be
expected to occur on the basis of instantaneous exposure to peak
pressure output from an airgun array while for low-frequency cetaceans,
potential auditory injury would occur on the basis of the accumulation
of energy output over time by an airgun array. For additional
discussion, please see NMFS (2018) and discussion provided in the 2018
notice of proposed rulemaking (83 FR 29212, June 22, 2018) and in the
notice of issuance for the 2021 final rule (86 FR 5322; January 19,
2021), e.g., 83 FR 29262; 86 FR 5354; 86 FR 5397. Importantly, the
modeled exposure estimates do not account for either aversion or the
beneficial impacts of the required mitigation measures.
Of even greater import for mid-frequency cetaceans is that the
small calculated Level A harassment zone size in conjunction with the
properties of sound fields produced by arrays in the near field versus
far field leads to a logical conclusion that Level A harassment is so
unlikely for species in this hearing group as to be discountable. For
all mid-frequency cetaceans, following evaluation of the available
scientific literature regarding the auditory sensitivity of mid-
frequency cetaceans and the properties of airgun array sound fields,
NMFS does not expect any reasonable potential for Level A harassment to
occur. This issue was addressed in detail in the response to public
comments provided in NMFS' 2021 notice of issuance for the rule (86 FR
5322, January 19, 2021; see 86 FR 5354). NMFS expects the potential for
Level A harassment of mid-frequency cetaceans to be discountable, even
before the likely moderating effects of aversion and mitigation are
considered, and NMFS does not believe that Level A harassment is a
likely outcome for any mid-frequency cetacean. Therefore, the updated
modeling results provided by Weirathmueller et al. (2022) account for
this by assuming that any estimated exposures above Level A harassment
thresholds for mid-frequency cetaceans resulted instead in Level B
harassment (as reflected in table 6).
As discussed in greater detail in the 2018 notice of proposed
rulemaking (83 FR 29212, June 22, 2018), NMFS considered the
possibility of incorporating quantitative adjustments within the
modeling process to account for the effects of mitigation and/or
aversion, as these factors would lead to a reduction in likely
injurious exposure. However, these factors were ultimately not
quantified in the modeling. In summary, there is too much inherent
uncertainty regarding the effectiveness of detection-based mitigation
to support any reasonable quantification of its effect in reducing
injurious exposure, and there is too little information regarding the
likely level of onset and degree of aversion to quantify this behavior
in the modeling process. This does not mean that mitigation is not
effective (to some degree) in avoiding incidents of Level A harassment,
nor does it mean that aversion is not a meaningful real-world effect of
noise exposure that should be expected to reduce the number of
incidents of Level A harassment. As discussed in greater detail in
responses to public comments provided in the 2021 notice of issuance
for the final rule (86 FR 5322, January 19, 2021; see 86 FR 5353),
there is ample evidence in the literature that aversion is one of the
most common responses to noise exposure across varied species, though
the onset and degree may be expected to vary across individuals and in
different contexts. Therefore, NMFS incorporated a reasonable
adjustment to modeled Level A harassment exposure estimates to account
for aversion for low- and high-frequency species. That approach, which
is retained here, assumes that an 80 percent reduction in modeled
exposure estimates for Level A harassment for low- and high-frequency
cetaceans is reasonable (Ellison et al., 2016) and likely conservative
in terms of the overall numbers of actual incidents of Level A
harassment for these species, as the adjustment does not explicitly
account for the effects of mitigation. This adjustment was incorporated
into the updated modeling results provided by Weirathmueller et al.
(2022) and reflected in table 6.
Take Estimation Error--As discussed previously, in 2020 BOEM
provided an update to the scope of their proposed action through
removal of the area subject to leasing moratorium under GOMESA from
consideration in the rule. In support of this revision, BOEM provided
revised 5-year level of effort predictions and associated acoustic
exposure estimates. BOEM's process for developing this information,
described in detail in ``Revised Modeled Exposure Estimates''
(available online at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>), was straightforward. Rather than using the PEIS's 10-year
period, BOEM provided revised levels of effort for a 5-year period,
using years 1-5 of the original level of effort projections. BOEM
stated that the first 5 years were selected to be carried forward
``because they were contiguous, they included the three years with the
most activity, and they were the best understood in relation to the
historical data upon which they are based.'' Levels of effort, shown in
table 1, were revised based on the basic assumption that if portions of
areas are removed from consideration, then the corresponding effort
previously presumed to occur in those areas also is removed from
consideration. Projected levels of effort were reduced in each zone by
the same proportion as was removed from each zone when BOEM reduced the
scope of its proposed action, i.e., the levels of effort were reduced
by the same zone-specific proportions shown in table 1 in the notice of
issuance for the final rule (86 FR 5322, January 19, 2021). Associated
revised take estimates were provided by BOEM and evaluated in the final
rule.
While processing requests for individual LOAs in 2021 under the
rule using the methodology for developing LOA-specific take numbers
presented in the rule, NMFS discovered discrepancies between the
revised total take numbers provided by BOEM when addressing its
revision to the scope of activity through removal of the GOMESA area
and the underlying modeling results. (Note that the underlying modeling
results are in the form of 24-hour exposure estimates, specific to each
species, zone, survey type, and season. These 24-hour exposure
estimates can then be scaled to generate take numbers appropriate to
the specific activity or, in the case of BOEM's petition for
rulemaking, to the
[[Page 31512]]
total levels of activity projected to occur across a number of years.)
NMFS contacted BOEM regarding the issue in June 2021. Following an
initial discussion, BOEM determined that when it reduced its scope of
specified activity by removing the GOMESA moratorium area from the
proposed action, it underestimated the level of take by inadvertently
factoring species density estimates into its revised exposure estimates
twice. Generally, this miscalculation caused BOEM to underestimate the
total predicted exposures of species from all survey activities in its
revision to the incidental take rule application, most pronouncedly for
those species with the lowest densities. The practical effect of this
miscalculation is that the full amount of activity for which BOEM
sought incidental take coverage in its application cannot be authorized
under the existing incidental take rule.
In September 2021, BOEM provided corrected exposure estimates.
These are available in BOEM's September 2021 ``Corrected Exposure
Estimates'' letter, available online at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>. Following receipt
of BOEM's letter containing corrected exposure estimates, NMFS
requested additional information from BOEM, including a detailed
written description of the process involved in producing the revised
take numbers submitted in 2020, the error(s) in that process, and the
process involved in correcting those numbers. BOEM provided the
requested information in October 2021. A detailed description of this
explanation was provided in the notice of proposed rulemaking (88 FR
916, January 5, 2023). Please see that notice and BOEM's letter for
additional detail.
The result of BOEM's process was that errors of varying degrees
were introduced to the BOEM-derived take numbers evaluated in the final
rule. Although NMFS was unable to replicate the derivation of the
species-specific scaling factors, or to adequately compare the
erroneous BOEM-derived values to the values evaluated in NMFS' 2018
proposed rule or to other published values, it remained clear that the
take estimates were significantly underestimated for multiple species.
Because of this, recalculation of appropriate take numbers was
necessary.
New Modeling--Once it became clear that NMFS would need to
recalculate the take numbers in order to support the necessary
correction and reanalysis under the rule, we recognized that two other
primary pieces of new information should be considered.
As discussed previously, through NMFS' experience implementing the
2021 final rule, it has become evident that operators are not currently
using airgun arrays as large as the proxy array specified by BOEM for
the original exposure modeling effort, and that the use of that 72-
element, 8,000-in\3\ array as the proxy for generating LOA-specific
take estimates is overly conservative. As a result, operators applying
8,000-in\3\ modeled results to operations conducted with smaller airgun
arrays have been inappropriately limited in the number of planned days
of data acquisition when NMFS' small numbers limit has been reached.
Therefore, independently of and prior to the above-described discovery
and evaluation of BOEM's error, NMFS had already determined that it
would be useful and appropriate to produce new modeling results
associated with a more representative airgun array. In consultation
with industry operators, NMFS identified specifications associated with
a 32-element, 5,110 in\3\ array and contracted with the same modelers
that produced the original acoustic exposure modeling (JASCO Applied
Sciences) to conduct new modeling following the same approach and
methodologies described in detail in Zeddies et al. (2015, 2017a). This
information was reflected in NMFS' proposed rule and available for
public review and comment (83 FR 29212, June 22, 2018). Specifically,
JASCO has now produced new comprehensive modeling results for all
evaluated survey types for the three different arrays described
previously: (1) 4,130-in\3\ array, described in detail in Zeddies et
al. (2017b) (acoustic exposure results were provided for only 6 species
in Zeddies et al. (2017b); full results are now available); (2) 5,110-
in\3\ array specified by NMFS and described in Weirathmueller et al.
(2022); and (3) 8,000-in\3\ array described in detail by Zeddies et al.
(2015, 2017a).
Since the time of the original acoustic exposure modeling, JASCO
has reviewed all species definition files and applied extensive updates
for many species. These files define the species-specific parameters
that control animat behavior during animal movement modeling. In
particular, changes in the minimum and maximum depth preferences
affected the coverage area for several species, which resulted in
significant changes to some estimated exposures for some species.
In addition, at the time NMFS determined it would conduct a
rulemaking to address the corrected take estimates, new cetacean
density modeling (including incorporation of new Rice's whale data) was
nearing completion, in association with the BOEM-funded GoMMAPPS effort
(see: <a href="https://www.boem.gov/gommapps">https://www.boem.gov/gommapps</a>). NMFS determined that this new
information (updated acoustic exposure modeling and new cetacean
density models) should be used as the best available information for
this rulemaking, and as such it is the basis for our analyses. For
purposes of the negligible impact analyses, NMFS uses the maximum of
the species-specific exposure modeling results from the three airgun
array configurations/sizes. Specifically, for all species other than
Rice's whale, these results are associated with the 8,000-in\3\ array.
For the Rice's whale, modeling associated with the 5,110-in\3\ array
produced larger exposure estimates (discussed below).
Estimated instances of take, i.e., scenario-specific acoustic
exposure estimates incorporating the adjustments to Level A harassment
exposure estimates discussed here, are shown in table 6. For
comparison, table 5 shows the estimated instances of take evaluated in
the 2021 final rule. This information regarding total number of takes
(with Level A harassment takes based on assumptions relating to mid-
frequency cetaceans in general as well as aversion), on an annual basis
for 5 years, provides the bounds within which incidental take
authorizations--LOAs--may be issued in association with this regulatory
framework. Importantly, modeled results showed increases in total take
estimates for 4 species, while the others decreased from those analyzed
in the 2021 final rule.\8\
---------------------------------------------------------------------------
\8\ Note that because of the new category of blackfish, there is
uncertainty on any change in the take numbers for the individual
species that comprise that category, though collectively the take
numbers for all the blackfish remain within the levels previously
analyzed.
---------------------------------------------------------------------------
Typically, and especially in cases where PTS is predicted, NMFS
anticipates that some number of individuals may incur temporary
threshold shift (TTS). However, it is not necessary to separately
quantify those takes, as it is unlikely that an individual marine
mammal would be exposed at the levels and duration necessary to incur
TTS without also being exposed to the levels associated with potential
disruption of behavioral patterns (i.e., Level B harassment). As such,
NMFS expects any potential TTS takes to be captured by the estimated
Level B harassment takes associated with behavioral disturbance
(discussed below).
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[[Page 31514]]
[GRAPHIC] [TIFF OMITTED] TR24AP24.074
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Discussion of Estimated Take
Differences between the estimated instances of take evaluated in
the 2021 final rule (table 5) and those evaluated herein (table 6) may
be attributed to multiple factors. Due to the confounding nature of
these factors, it is challenging to attribute species-specific
differences by degree to any particular factor. These factors include:
(1) BOEM errors in calculating estimated take in support of its
revision of scope for the 2021 final rule, which are related to
species-specific density values by zone, as well as to species-specific
``correction factors'' developed by BOEM; (2) JASCO revisions to
species definition files governing animat behavior during animal
movement modeling; and (3) new density information for all species
other than Fraser's dolphin and rough-toothed dolphin. In addition, for
the Rice's whale, propagation modeling of a new array specification
produced the greatest values for estimated instances of take. While it
is difficult to attribute species-specific changes to specific factors,
we do know that the correction of the BOEM error could only result in
take number increases from the 2021 final rule, while density changes
and species definition file changes could result in either increases or
decreases in take estimates. (However, most density values decreased,
in many cases significantly.) NMFS has addressed BOEM's error to the
extent possible in the discussion provided previously (see Take
Estimation Error).
Regarding the species characteristics used in the new modeling, as
discussed above, all species behavior files were reviewed by JASCO
prior to the new
[[Page 31515]]
modeling, and many had extensive updates, based on the availability of
new information regarding relevant behavioral parameters in the
scientific literature. In particular, changes in the minimum and
maximum depth preferences affected the coverage area for several
species, which resulted in changes to some species exposures.
New modeling for the smaller, 5,110-in\3\ array illustrated that
the larger array is not necessarily always more impactful. Free-field
beam patterns are different for the arrays as are the tow depths. The
5,110-in\3\ array was specified as being towed at 12 m depth (following
typical usage observed by NMFS through review of LOA applications),
while the other arrays are assumed to use an 8-m tow depth (assumptions
regarding source specifications were made by BOEM as part of its
original petition for rulemaking). The depth at which a source is
placed influences the interference pattern caused by the direct and
sea-surface reflected paths (the ``Lloyd's mirror'' effect). The
destructive interference from the sea-surface reflection is generally
greater for shallow tow depths compared to deeper tow depths. In
addition, interactions between source depth, beam pattern geometry,
source frequency content, the environment (e.g., bathymetry and sound
velocity profile), and different animat seeding depths and behaviors
can give unexpected results. For example, while the larger array may
have the longest range for a particular isopleth (sound contour), the
overall sound field coverage area was found to have greater asymmetry
as a result of the above-mentioned interactions.
While the larger array did produce greater predicted exposures for
all species, with the exception of Rice's whales, the differences
between predicted exposure estimates for the two larger arrays were not
as great as may have been expected on the basis of total array volume
alone. The 5,110- and 8,000-in\3\ arrays were often similar in terms of
predicted exposures, although the beam patterns were quite different.
For arrays of airgun sources, the chamber volume or the total array
volume is not the only meaningful variable. Although it is true that a
source with a larger volume is generally louder, in practice this only
applies largely to single sources or small arrays of sources and was
not the case for the considered arrays. As discussed above, array
configuration, tow depth, and bathymetry were significant factors. For
example, the 8,000-in\3\ array generally had a more directional beam
pattern than the 4,130- or 5,110-in\3\ arrays. The vertical structure
of the sound field combined with different species' dive depth and
surface intervals was important as well. Differences in estimated take
numbers for the 2021 final rule and this rule, i.e., differences
between tables 5 and 6, are shown in table 7.
[GRAPHIC] [TIFF OMITTED] TR24AP24.075
NMFS cautions against interpretation of the changes presented in
table 7 at face value for a variety of reasons. First, reasons for the
differences in the take estimates are difficult to interpret due to the
confounding nature of the different factors discussed in this section.
Second, the meaning of the differences in terms of impacts to the
affected
[[Page 31516]]
species or stocks is similarly not as straightforward as the magnitude
and direction of the differences may imply. Differences in estimated
take are, in part, the result of the introduction of new density data,
which also provides new model-predicted abundance estimates. Our
evaluation under the MMPA of the expected impacts of the predicted take
events is substantially reliant on comparisons of the expected take to
the predicted abundance. See discussion of our evaluation of severity
of impact (one prong of analysis) in Negligible Impact Analysis and
Determinations. The severity of the predicted taking is understood
through the estimates' relationship to predicted zone-specific
abundance values, and so the absolute differences presented in table 7
are not, alone, informative in that regard.
Overall, NMFS has determined, to the extent possible, that aside
from the confounding effect of BOEM's calculation errors, differences
between the current and prior results for the 8,000-in\3\ array are
primarily attributable to differences in species density along with
changes in the species behavior files, in particular minimum and
maximum animat seeding depths.
Level B Harassment
NMFS has determined the values shown in table 6 are a reasonable
estimate of the maximum potential instances of take that may occur in
each year of the regulations based on projected effort (more
specifically, each of these ``takes'' represents a day in which one
individual is exposed above the Level B harassment criteria, even if
only for minutes). However, these take numbers do not represent the
number of individuals expected to be taken, as they do not consider the
fact that certain individuals may be exposed above harassment
thresholds on multiple days. Accordingly, as described in the 2018
notice of proposed rulemaking, NMFS developed a ``scalar ratio''
approach to inform two important parts of the analyses: understanding a
closer approximation of the number of individuals of each species or
stock that may be taken within a survey, and understanding the degree
to which individuals of each species or stock may be more likely to be
repeatedly taken across multiple days within a year.
In summary, comparing the results of modeling simulations that more
closely match longer survey durations (30 days) to the results of 24-
hour take estimates scaled up to 30 days (as the instances of take in
table 6 were calculated) provides the comparative ratios of the numbers
of individuals taken/calculated (within a 30-day survey) to instances
of take, in order to better understand the comparative distribution of
exposures across individuals of different species. These products are
used to inform a better understanding of the nature in which
individuals are taken across the multiple days of a longer duration
survey given the different behaviors that are represented in the animat
modeling and may appropriately be used in combination with the
calculated instances of take to predict the number of individuals taken
for surveys of similar duration, in order to support evaluation of take
estimates in requests for LOAs under the ``small numbers'' standard,
which is based on the number of individuals taken. A detailed
discussion of this approach was provided in the 2018 notice of proposed
rulemaking. As NMFS retains without change this ``scalar ratio''
approach to approximating the number of individuals taken, both here
(see Negligible Impact Analysis and Determinations) and in support of
the necessary small numbers determination on an LOA-specific basis, we
do not repeat the discussion but refer the reader to previous Federal
Register notices. Application of the scaling method reduced the overall
magnitude of modeled takes for all species by a range of slightly more
than double up to tenfold (table 8).
These adjusted take numbers, representing a closer approximation of
the number of individuals taken (shown in table 8), provide a more
realistic basis upon which to evaluate severity of the expected taking.
Please see the Negligible Impact Analysis and Determinations section
later in this document for additional detail. It is important to
recognize that while these scaled numbers better reflect the number of
individuals likely to be taken within a single 30-day survey than the
number of instances in table 6, they will still overestimate the number
of individuals taken across the aggregated GOM activities, because they
do not correct for (i.e., further reduce take to account for)
individuals exposed to multiple surveys or fully correct for
individuals exposed to surveys significantly longer than 30 days.
As noted in the beginning of this section and in the Small Numbers
section, using modeled instances of take (table 6) and the method used
here to scale those numbers allows one to more accurately predict the
number of individuals that will be taken as a result of exposure to one
survey and, therefore, these scaled predictions are more appropriate to
consider in requests for LOAs to assess whether a resulting LOA would
meet the small numbers standard. However, for the purposes of ensuring
that the total taking authorized pursuant to all issued LOAs is within
the scope of the analysis conducted to support the negligible impact
finding in this rule, authorized instances of take (which are the
building blocks of the analysis) also must be assessed. Specifically,
reflecting table 6 and what has been analyzed, the total instances of
take that may be authorized for any given species or stock over the
course of the 5 years covered under these regulations must not, and is
not expected to, exceed the sum of the 5 years of take indicated for
the 5 years in that table. Additionally, in any given year, the
instances of take of any species must not, and are not expected to,
exceed the highest annual take listed in table 6 for any of the 5 years
for a given species.
[[Page 31517]]
[GRAPHIC] [TIFF OMITTED] TR24AP24.085
Mitigation
``Least Practicable Adverse Impact'' Standard
Under section 101(a)(5)(A) of the MMPA, NMFS must set forth the
permissible methods of taking pursuant to such activity, and other
means of effecting the LPAI on such species or stock and its habitat,
paying particular attention to rookeries, mating grounds, and areas of
similar significance, and on the availability of such species or stock
for subsistence uses, often referred to in shorthand as ``mitigation.''
NMFS does not have a regulatory definition for LPAI. However, NMFS'
implementing regulations require applicants for incidental take
authorizations to include information about the availability and
feasibility (economic and technological) of equipment, methods, and
manner of conducting such activity or other means of effecting the LPAI
upon the affected species or stocks and their habitat (50 CFR
216.104(a)(11)). In the Mitigation section of the 2021 final rule, NMFS
included a detailed description of our interpretation of the LPAI
standard (including its relationship to the negligible impact standard)
and how the LPAI standard is implemented (86 FR 5322, 5407, January 19,
2021). We refer readers to the full LPAI discussion in the 2021 final
rule, but repeat the discussion on implementation here to facilitate
understanding of the analyses that follow.
NMFS' evaluation of potential mitigation measures includes
consideration of two primary factors:
(1) The manner in which, and the degree to which, implementation of
the potential measure(s) is expected to reduce adverse impacts to
marine mammal species or stocks, their habitat, and their availability
for subsistence uses (where relevant). This analysis considers such
things as the nature of the potential adverse impact (such as
likelihood, scope, and range), the likelihood that the measure will be
effective if implemented, and the likelihood of successful
implementation; and
(2) The practicability of the measures for applicant
implementation. Practicability of implementation may consider such
things as cost, impact on activities, personnel safety, and
practicality of implementation.
While the language of the LPAI standard calls for minimizing
impacts to affected species or stocks and their habitat, NMFS
recognizes that the reduction of impacts to those species or stocks
accrues through the application of mitigation measures that limit
impacts to individual animals. Accordingly, NMFS' analysis focuses on
measures that are designed to avoid or minimize impacts on individual
marine mammals that are likely to increase the probability or severity
of population-level effects.
While direct evidence of impacts to species or stocks from a
specified activity is rarely available, and additional study is still
needed to understand how specific disturbance events affect the fitness
of individuals of certain species, there have been improvements in
understanding the process by which disturbance effects are translated
to the population. With recent scientific advancements (both marine
mammal energetic research and the development of energetic frameworks),
the relative likelihood or degree of impacts on species or stocks may
often be inferred given a detailed understanding of the activity, the
environment, and the affected species or stocks. This same information
is used in the development of mitigation measures and helps us
understand how mitigation measures contribute to lessening effects (or
the risk thereof) to species or stocks. NMFS also acknowledges that
there is always the potential that new information, or a new
recommendation that had not previously been considered, becomes
available and necessitates re-evaluation of mitigation measures (which
may be addressed through adaptive management) to see if further
reductions of population impacts are possible and practicable.
In the evaluation of specific measures, the details of the
specified activity will necessarily inform each of the two primary
factors discussed above (expected reduction of impacts and
practicability) and are carefully considered to determine the types of
mitigation that are appropriate under the LPAI standard. Analysis of
how a potential mitigation measure may
[[Page 31518]]
reduce adverse impacts on a marine mammal stock or species and
practicability of implementation are not issues that can be
meaningfully evaluated through a yes/no lens. The manner in which, and
the degree to which, implementation of a measure is expected to reduce
impacts, as well as its practicability, can vary widely. For example, a
time-area restriction could be of very high value for reducing the
potential for, or severity of, population-level impacts (e.g., avoiding
disturbance of feeding females in an area of established biological
importance) or it could be of lower value (e.g., decreased disturbance
in an area of high productivity but of less firmly established
biological importance). Regarding practicability, a measure might
involve restrictions in an area or time that impede the operator's
ability to acquire necessary data (higher impact), or it could mean
incremental delays that increase operational costs but still allow the
activity to be conducted (lower impact). A responsible evaluation of
LPAI will consider the factors along these realistic scales. Expected
effects of the activity and of the mitigation as well as status of the
stock all weigh into these considerations. Accordingly, the greater the
likelihood that a measure will contribute to reducing the probability
or severity of adverse impacts to the species or stock or their
habitat, the greater the weight that measure is given when considered
in combination with practicability to determine the appropriateness of
the mitigation measure, and vice versa. Consideration of these factors
is discussed in greater detail below.
1. Reduction of adverse impacts to marine mammal species or stocks
and their habitat.\9\
---------------------------------------------------------------------------
\9\ NMFS recognizes the LPAI standard requires consideration of
measures that will address minimizing impacts on the availability of
the species or stocks for subsistence uses where relevant. Because
subsistence uses are not implicated for this action, we do not
discuss them. However, a similar framework would apply for
evaluating those measures, taking into account both the MMPA's
directive that we make a finding of no unmitigable adverse impact on
the availability of the species or stocks for taking for
subsistence, and the relevant implementing regulations.
---------------------------------------------------------------------------
The emphasis given to a measure's ability to reduce the impacts on
a species or stock considers the degree, likelihood, and context of the
anticipated reduction of impacts to individuals (and how many
individuals) as well as the status of the species or stock.
The ultimate impact on any individual from a disturbance event
(which informs the likelihood of adverse species- or stock-level
effects) is dependent on the circumstances and associated contextual
factors, such as duration of exposure to stressors. Though any proposed
mitigation needs to be evaluated in the context of the specific
activity and the species or stocks affected, measures with the
following types of effects have greater value in reducing the
likelihood or severity of adverse species- or stock-level impacts:
avoiding or minimizing injury or mortality; limiting interruption of
known feeding, breeding, mother/young, or resting behaviors; minimizing
the abandonment of important habitat (temporally and spatially);
minimizing the number of individuals subjected to these types of
disruptions; and limiting degradation of habitat. Mitigating these
types of effects is intended to reduce the likelihood that the activity
will result in energetic or other types of impacts that are more likely
to result in reduced reproductive success or survivorship. It is also
important to consider the degree of impacts that are expected in the
absence of mitigation in order to assess the added value of any
potential measures. Finally, because the LPAI standard gives NMFS
discretion to weigh a variety of factors when determining appropriate
mitigation measures and because the focus of the standard is on
reducing impacts at the species or stock level, the LPAI standard does
not compel mitigation for every kind of take, or every individual
taken, if that mitigation is unlikely to meaningfully contribute to the
reduction of adverse impacts on the species or stock and its habitat,
even when practicable for implementation by the applicant.
The status of the species or stock is also relevant in evaluating
the appropriateness of potential mitigation measures in the context of
LPAI. The following are examples of factors that may (either alone, or
in combination) result in greater emphasis on the importance of a
mitigation measure in reducing impacts on a species or stock: the stock
is known to be decreasing or status is unknown, but believed to be
declining; the known annual mortality (from any source) is approaching
or exceeding the PBR level; the affected species or stock is a small,
resident population; or the stock is involved in a UME or has other
known vulnerabilities, such as recovering from an oil spill.
Habitat mitigation, particularly as it relates to rookeries, mating
grounds, and areas of similar significance, is also relevant to
achieving the standard and can include measures such as reducing
impacts of the activity on known prey utilized in the activity area or
reducing impacts on physical habitat. As with species- or stock-related
mitigation, the emphasis given to a measure's ability to reduce impacts
on a species or stock's habitat considers the degree, likelihood, and
context of the anticipated reduction of impacts to habitat. Because
habitat value is informed by marine mammal presence and use, in some
cases there may be overlap in measures for the species or stock and for
use of habitat.
NMFS considers available information indicating the likelihood of
any measure to accomplish its objective. If evidence shows that a
measure has not typically been effective nor successful, then either
that measure should be modified or the potential value of the measure
to reduce effects should be lowered.
2. Practicability.
Factors considered may include those costs, impact on activities,
personnel safety, and practicality of implementation.
Application of the LPAI Standard in this Action
In carrying out the MMPA's mandate for this action, NMFS applies
the context-specific balance between the manner in which and the degree
to which measures are expected to reduce impacts to the affected
species or stocks and their habitat and practicability for operators.
See NMFS' notice of issuance for the 2021 final rule (January 19, 2021,
86 FR 5322, 5405). The effects of concern (i.e., those with the
potential to adversely impact species or stocks and their habitat)
include auditory injury, severe behavioral reactions, disruptions of
critical behaviors, and to a lesser degree, masking and impacts on
acoustic habitat. These effects were addressed previously in the
Potential Effects of the Specified Activity on Marine Mammals and Their
Habitat and Anticipated Effects on Marine Mammal Habitat sections of
the 2018 notice of proposed rulemaking (June 22, 2018, 83 FR 29212,
29233, 29241).
Our rulemaking for the 2021 final rule focused on measures with
proven or reasonably presumed ability to avoid or reduce the intensity
of acute exposures that have potential to result in these anticipated
effects. To the extent of the information available to NMFS, we
considered practicability concerns, as well as potential undesired
consequences of the measures, e.g., extended periods using the acoustic
source due to the need to reshoot lines. NMFS recognized that
instantaneous protocols, such as shutdown requirements, are not capable
of avoiding all acute effects, are not
[[Page 31519]]
suitable for avoiding many cumulative or chronic effects, and do not
provide targeted protection in areas of greatest importance for marine
mammals. Therefore, in addition to a basic suite of seismic mitigation
protocols, we also evaluated time-area restrictions that would avoid or
reduce both acute and chronic impacts of surveys, including potential
restrictions that were removed from consideration in the final rule as
a result of BOEM's change to the scope of the action.
NMFS' 2021 rule included a suite of basic mitigation protocols that
are required regardless of the status of a stock. Additional or
enhanced protections were required for species whose stocks are in
particularly poor health and/or are subject to some significant
additional stressor that lessens that stock's ability to weather the
effects of the specified activities without worsening its status. NMFS'
evaluation process was described in detail in the 2018 proposed rule
(83 FR 29212, June 22, 2018), and mitigation requirements included in
the incidental take regulations at 50 CFR 217.180 et seq. were fully
described in the notice of issuance for the final rule (86 FR 5322,
5411, January 19, 2021).
For this current rulemaking, NMFS' evaluation built off the
existing mitigation requirements from the 2021 final rule, which will
remain in effect, and considered additional mitigation under the LPAI
standard as it relates to Rice's whales, in light of the species'
status, increase in take estimates relative to the 2021 final rule, and
other new information. In addition to other potential changes to
mitigation requirements suggested by public commenters and addressed in
the Comments and Responses section of this rule, we evaluated (1) a
potential restriction on survey activities within the small portion of
the Rice's whale ``core distribution area'' that overlaps the
geographic scope of the specified activity covered by this rule (see
discussion of the core distribution area earlier in Description of
Marine Mammals in the Area of the Specified Activities) and (2) the
potential for a restriction on survey activity in other areas between
100-400 m in depth throughout the geographic area covered by the
rule,\10\ also for Rice's whales. As described below, we determined
that the requirements in the current regulations promulgated under the
2021 final rule satisfy the LPAI standard and therefore make no changes
to those regulations. Because the mitigation requirements for this
action are the same as those described in the final rule (86 FR 5322,
5409, January 19, 2021), we do not repeat the description of the
required mitigation.
---------------------------------------------------------------------------
\10\ Subsequent to publication of the 2023 proposed rule, NMFS
proposed to designate the area in the GOM, between the U.S. EEZ off
Texas east to the boundary between the South Atlantic Fishery
Management Council and the Gulf of Mexico Fishery Management Council
off of Florida, that consists of waters from the 100 m isobaths to
the 400 m isobaths, as critical habitat for the Rice's whale (88 FR
47453, July 24, 2023).
---------------------------------------------------------------------------
For all other species, although there are slight increases in
estimated take (for three species) and increases in evaluated risk (for
other species) relative to the 2021 final rule (see Negligible Impact
Analysis and Determinations), there are no known specific areas of
particular importance to consider for time-area restrictions, and no
changes to our prior analysis for the sufficiency of the existing
standard operational mitigation requirements to effect the LPAI on the
affected species or stocks and their habitat. (We also note that NMFS'
2018 proposed rule made this determination even in the context of
significantly higher takes, as well as evaluated risk.)
Rice's Whale--We first provide a summary of baseline information
relevant to our consideration of mitigation for Rice's whales. Rice's
whales have a small population size, are restricted to the GOM, and
were determined by the status review team to be ``at or below the near-
extinction population level'' (Rosel et al., 2016). While various
population abundance estimates are available (e.g., Garrison et al.,
2020, 2023; Hayes et al., 2020; Roberts et al., 2016; Dias and
Garrison, 2016), all are highly uncertain because targeted surveys have
not been conducted throughout the Rice's whale's range. The most recent
statistically-derived abundance estimate, from 2017-2018 surveys in the
northeastern GOM, is 51 individuals (20-130 95% Confidence Interval
(CI)) (Garrison et al., 2020). There may be fewer than 100 individuals
throughout the GOM (Rosel et al., 2016). In addition, the population
exhibits very low levels of genetic diversity (Rosel and Wilcox, 2014;
Rosel et al., 2021). The small population size, restricted range, and
low genetic diversity alone place these whales at significant risk of
extinction (IWC, 2017). This risk has been exacerbated by the effects
of the DWH oil spill, which was estimated to have exposed up to half
the population to oil (DWH NRDA Trustees, 2016; DWH MMIQT, 2015). In
addition, Rice's whales face a significant suite of anthropogenic
threats, including noise produced by airgun surveys (Rosel et al.,
2016). Additionally, Rice's whale dive and foraging behavior places
them at heightened risk of being struck by vessels and/or entangled in
fishing gear (Soldevilla et al., 2017).
Of relevance here, the reduced geographic scope of the specified
activity for this rule (and the 2021 final rule) in relation to the
2018 proposed rule excludes the eastern GOM through removal of the
GOMESA area (see Figure 2). This reduced scope effectively minimizes
potential impacts to Rice's whales and their core habitat (as
recognized by the 2016 status review team) relative to the impacts
considered through NMFS' 2018 proposed rule. Thus, although potential
takes considered herein are higher relative to those analyzed in the
2021 final rule (maximum of 30 annual incidents of take (Level B
harassment only) compared with 10, respectively), they remain
significantly under the take numbers evaluated in the 2018 proposed
rule (maximum of 572 annual incidents of take by Level B harassment
with additional take by Level A harassment).
It is in the aforementioned context that our 2023 proposed rule
evaluated two potential measures for additional Rice's whale
mitigation: (1) restriction of survey activity within the 5 percent of
the core distribution area (i.e., the expanded area around northeastern
GOM Rice's whale sightings and tagged whale locations created through
application of a 30 km buffer) that is within the geographic scope of
the specified activity; and (2) restriction of survey activity over a
broad (but undefined) area of the central and/or western GOM within
Rice's whale habitat in waters between the 100-400 m isobaths. There is
no scientific information supporting a temporal component for either
potential restriction nor any specific spatial definition for a central
and/or western GOM restriction. Following the LPAI analysis produced in
the 2023 proposed rule, the MMC recommended implementing restriction
(1) above. Both the MMC and NRDC commented that some surveys should be
restricted within habitat of the central and/or western GOM, but
neither commenter provided recommendations regarding specific
recommended spatial definition of such a restriction or specific
metrics for defining which surveys should be restricted. All comments
and recommendations were evaluated and responses are provided earlier.
See Comments and Responses.
We reiterate that the amount of anticipated take of Rice's whales
over the 5-year duration of the incidental take regulation is
relatively low and
[[Page 31520]]
limited to Level B harassment. The anticipated magnitude of impacts
from any of these anticipated takes is considered to be relatively low,
as we concluded that none of these takes are expected to impact the
fitness of any individuals. See Negligible Impact Analysis and
Determinations. We also note the robust shutdown measures required that
utilize highly effective visual and passive acoustic detection methods
to avoid marine mammal injury as well as minimize TTS and more severe
behavioral responses.
For this rulemaking, NMFS independently examined each of the two
area-based restrictions in the context of the LPAI standard to
determine whether either restriction is warranted to minimize the
impacts from seismic survey activities on the affected marine mammal
species or stocks. This analysis is consistent with the consideration
of the LPAI criteria described above when determining appropriateness
of mitigation measures. These potential requirements were evaluated
(see below) in the context of the proposed seismic survey activities
(including the geographic scope of the rule) and the existing
mitigation measures that would be implemented to minimize impacts on
the affected marine mammal species or stocks from these activities.
To reiterate, the scope of the rule does not cover Rice's whale
core habitat in the northeastern GOM, which is the area (absent
buffering) that contains the highest known densities of Rice's whale
and which has defined the movements of previously tagged Rice's whales.
Thus, even though individual Rice's whales occurring outside of the
core habitat area may experience harassment, this geographic scope
likely precludes significant impacts to Rice's whales at the species
level by avoiding takes of the majority of individuals and by avoiding
impacts to the habitat that supports the highest densities of the
species. This important context generally lessens the total number of
takes, and means that the takes that do occur are expected to have
lower potential to have negative energetic effects or deleterious
effects on reproduction that could reduce the likelihood of survival or
reproductive success. In addition, NMFS has required mitigation
measures that would minimize or alleviate the likelihood of injury
(PTS), TTS, and more severe behavioral responses (the 1,500-m shutdown
zone). In addition, exposures to airgun noise would occur in open water
areas where animals can more readily avoid the source and find
alternate habitat relatively easily. The existing mitigation
requirements are expected to be effective in ensuring that impacts are
limited to lower-level responses with limited potential to
significantly alter natural behavior patterns in ways that would affect
the fitness of individuals and by extension the affected species.
As noted previously, in evaluating mitigation for species or stocks
and their habitat, we consider the expected benefits of the mitigation
measures for the species or stocks and their habitats against the
practicability of implementation. This consideration includes assessing
the manner in which, and the degree to which, the implementation of the
measure(s) is expected to reduce impacts to marine mammal species or
stocks (including through consideration of expected reduced impacts on
individuals), their habitat, and their availability for subsistence
uses (where relevant). This analysis considers such things as the
nature of the proposed activity's adverse impact (likelihood, scope,
range); the likelihood that the measure will be effective if
implemented; the likelihood of successful implementation.
Practicability of implementing the measure is also assessed and may
involve consideration of such things as cost and impact on operations
(16 U.S.C. 1371(a)(5)(A)(iii)).
Taking into account the above considerations, NMFS' evaluation of
the two potential survey restrictions is described below:
Core Distribution Area. NMFS' 2018 notice of proposed rulemaking
considered restrictions on activity in a Rice's whale ``core habitat
area'' in the eastern GOM identified between the 100- and 400-m
isobaths from 87.5[deg] W to 27.5[deg] N, based on Rosel et al. (2016)
(Figure 3). As discussed in the 2018 proposed rule, and above, a
restriction on (or absence of) survey activity in the core habitat area
would be expected to protect Rice's whales through the alleviation or
minimization of a range of airgun effects, both acute and chronic, that
could otherwise accrue to impact the reproduction or survival of
individuals in the area considered to be of greatest importance to the
species. The absence of survey activity in the species' core habitat
area not only minimizes Level B harassment of Rice's whales, but also
importantly minimizes other effects such as loss of communication
space.
The significant concern that led NMFS to consider restrictions on
survey activity in the core habitat area was largely alleviated through
removal of GOMESA and the associated reduction in predicted take and
impacts in a known area of important habitat. (Although predicted take
numbers for this final rule are higher relative to the 2021 final rule
(annual average Level B harassment events of 26 versus 8,
respectively), they remain significantly lower than the annual average
of 462 Level B harassment events considered in that 2018 analysis (plus
some potential for Level A harassment to occur)--an almost 18-fold
reduction.) Moreover, the functional absence of survey activity in the
eastern GOM, and particularly within Rice's whale core habitat area,
means that the anticipated protection afforded by the previously
considered restriction was functionally achieved by virtue of the
reduced scope for the 2021 final rule (which is unchanged for this
action). Regardless, because the core habitat area was entirely located
in the GOMESA moratorium area removed from the scope of the 2021 final
rule, it was no longer relevant for consideration as mitigation.
More recently, Rosel and Garrison (2022) described a Rice's whale
``core distribution area'' (Figure 3). This core distribution area
description included a precautionary 30-km buffer around the core
habitat area to account for uncertainty associated with both the
location of observed whales and the possible movement whales could make
in any direction from an observed sighting. It is not the result of new
information warranting an expansion of the previously considered core
habitat area, but rather is the result of additional precaution in
defining the area within which existing Rice's whale sightings and tag
locations suggest that whales could occur. As a result of this buffer,
approximately 5 percent of the polygon for the core distribution area
described in Rosel and Garrison (2022) overlaps with the current
geographic scope of the rule, which led us to consider whether
additional mitigation is warranted under the LPAI standard.
[[Page 31521]]
[GRAPHIC] [TIFF OMITTED] TR24AP24.076
The result of this precautionary approach is that areas shallower
than 100 m and deeper than 400 m (i.e., areas that are not known to
support all of the Rice's whale life history stages; NMFS, 2023) are
included in the core distribution area, most notably in the small
portion overlapping with the scope of this rule, given the steep
bathymetry there. Of the small portion of the core distribution area
that overlaps the scope of this rule, 76 percent covers waters
shallower than 100 m (36 percent) or deeper than 400 m (40 percent),
i.e., three-quarters of the area considered as a potential restriction
area covers waters considered outside of most suitable Rice's whale
habitat. We note that (1) NMFS' 2023 proposed designation of critical
habitat (which is based on the same information we have considered)
includes only waters between 100-400 m as the area containing physical
or biological features essential for conservation and (2) no confirmed
Rice's whale sightings have occurred in waters shallower than 100 m or
waters deeper than 408 m.
Thus, we evaluate the potential mitigative benefits of a
restriction on survey activity in the remaining approximately one-
quarter of the considered area that is preferred habitat for Rice's
whales. The absence of survey activity would avoid likely Level B
harassment of any individuals that may occur in the area, but there is
no information suggesting that the area is of particular importance
relative to the remainder of GOM waters between 100-400 m that are
outside the northeastern GOM core habitat, and Level B harassment that
occurs to whales present outside the core habitat area may be expected
to carry less potential for disruption of important behavior or
significance to the affected individual. The amount of anticipated take
is already low, and the existing mitigation requirements are expected
with a high degree of confidence to minimize the duration and intensity
of any instances of take that do occur. Therefore, we have low
confidence that this potential restriction would meaningfully reduce
impacts at the species or stock level. Regarding practicability,
although the considered area is relatively small, it would have outsize
impacts should any operator need to conduct new survey activity on
existing interests in the area or inform developers' understanding of
potential reserves in the area.
In summary, there is no information supporting identification of
this area (i.e., the 5 percent of the core distribution area
overlapping the scope of this rule) as being of particular importance
relative to Rice's whale habitat more broadly (i.e., GOM waters between
100-400 m depth), and only 24 percent of the overlapping area actually
covers Rice's whale habitat. The available information does not support
a conclusion that such a restriction would contribute meaningfully to a
reduction in adverse impacts to the Rice's whale or its habitat and,
therefore, there is no rationale for incurring the associated
practicability impacts. Because of these considerations, NMFS has
determined that a restriction on survey activity within the portion of
the core distribution area that occurs within scope of the rule is not
warranted.
Central and Western GOM. New information regarding Rice's whale
occurrence in the central and western GOM, largely based on passive
acoustic detections (Soldevilla et al., 2022;
[[Page 31522]]
2024), is now available. We acknowledge that some whales are likely to
be present at locations outside the northeastern GOM core habitat area,
and we considered whether other closure areas may be warranted,
including central and western GOM areas within the same general 100-400
m depth range known to be occupied by Rice's whales in the northeastern
GOM, and which have been proposed as designated critical habitat for
the species (88 FR 47453, July 24, 2023). We provide discussion of this
information and an evaluation of a potential broader restriction on
survey effort in the following paragraphs.
As background, a NOAA survey reported observation of a Rice's whale
in the western GOM in 2017 (NMFS, 2018). Genetic analysis of a skin
biopsy that was collected from the whale confirmed it to be a Rice's
whale. There had not previously been a genetically verified sighting of
a Rice's whale in the western GOM, and given the importance of this
observation, additional survey effort was conducted in an attempt to
increase effort in the area. However, no additional sightings were
recorded. (Note that there were two sightings of unidentified large
baleen whales in 1992 in the western GOM, recorded as Balaenoptera sp.
or Bryde's/sei whale (Rosel et al., 2021).) Subsequently, during recent
2023 survey effort in the western GOM, a sighting of what has been
described as a group of two probable Rice's whales was recorded
(<a href="https://www.fisheries.noaa.gov/science-blog/successful-final-leg-gulf-mexico-marine-mammal-and-seabird-vessel-survey">https://www.fisheries.noaa.gov/science-blog/successful-final-leg-gulf-mexico-marine-mammal-and-seabird-vessel-survey</a>). In addition, there are
occasional sightings by PSOs of baleen whales in the GOM that may be
Rice's whales. Rosel et al. (2021) reviewed 13 whale sightings reported
by PSOs in the GOM from 2010-2014 that were recorded as baleen whales.
No sightings were close enough for the PSOs to see the diagnostic three
lateral ridges on the whales' rostrums required to confirm them as
Rice's whales. Rosel et al. ruled out five of the sightings as more
likely being sperm whales based on water depth and descriptions of the
whales' behavior. The remaining eight sightings may have been Rice's
whales based on one or more lines of evidence (i.e., photographs,
behavioral description, and/or water depth consistent with Rice's
whales). Of these sightings, three occurred in the northeastern GOM
core habitat area, while the remaining five occurred along the GOM
shelf break south of Louisiana. See Figure 4 for the location of
confirmed Rice's whale sightings.
The acoustic detections provide significant evidence of year-round
Rice's whale presence outside of the northeastern GOM core habitat
area. Soldevilla et al. (2022) deployed autonomous passive acoustic
recorders at 5 sites along the GOM shelf break in predicted Rice's
whale habitat (Roberts et al., 2016) for 1 year (2016-2017) to (1)
determine if Rice's whales occur in waters beyond the northeastern GOM
and, if so, (2) evaluate their seasonal occurrence and site fidelity at
the 5 sites. Over the course of the 1-year study, sporadic, year-round
recordings of calls assessed as belonging to Rice's whales were made
south of Louisiana within approximately the same depth range (200-400
m), indicating that some Rice's whales occurred regularly in waters
beyond the northeastern GOM core habitat area during the study period.
Based on the detection range of the sonobuoys and acoustic monitors
used in the study, actual occurrence could be in water depths up to 500
m (M. Soldevilla, pers. comm.), though the deepest confirmed Rice's
whale sighting is at 408 m water depth. Data were successfully
collected at four of the five sites; of those four sites, Rice's whale
calls were detected at three. Detection of calls ranged from 1 to 16
percent of total days at the three sites. Calls were present in all
seasons at two sites, with no obvious seasonality. It remains unknown
whether animals are moving between the northwestern and the
northeastern GOM or whether these represent different groups of animals
(Soldevilla et al., 2022).
[[Page 31523]]
[GRAPHIC] [TIFF OMITTED] TR24AP24.077
A subsequent follow-up study (Soldevilla et al., 2024) similarly
involved deployment of autonomous passive acoustic recorders for
approximately one y
[…truncated; see source link]Indexed from Federal Register on April 24, 2024.
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