Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Geophysical Surveys in the Gulf of Mexico, 31488-31541 [2024-08257]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[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 [www.gpo.gov]
[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: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico. 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:
     Standard detection-based mitigation measures, including 
use of visual and acoustic observation to detect marine mammals and 
shut down acoustic sources in certain circumstances;
     A time-area restriction designed to avoid effects to 
bottlenose dolphins in times and places believed to be of particular 
importance;
     Vessel strike avoidance measures; and
     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 
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico.
    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: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico. 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: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico. 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 https://www.fisheries.noaa.gov/issued-letters-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico).
    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: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico.
    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: https://www.regulations.gov. 
A direct link to these comments is provided at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico.

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

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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 https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico). 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:
     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.
     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.
     Summarized metrics on R95 and 
Rmax 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 R95 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, R95 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 Rmax for a given sound level is simply the 
distance to the farthest occurrence of the threshold level 
(equivalent to R100. It is more conservative than 
R95, 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, Rmax would be much 
larger than R95 and could therefore be misleading 
if not given along with R95 (Zeddies et al., 
2015).
---------------------------------------------------------------------------

    Regarding this request, NMFS explained to EnerGeo that JASCO did 
not specifically calculate R95 and Rmax 
for every site, because Rmax/R95 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:
     Airgun array size (including total volume, number of array 
elements, element air pressure, array geometry and spacing) used in 
source and propagation models;
     Acoustic threshold criteria and associated weighting used 
to calculate exposures;
     Animal densities used for adjusting simulated computer 
model exposures to potential real-world animal exposures;
     Natural aversive behaviors of marine mammals; and
     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 https://www.fisheries.noaa.gov/southeast/endangered-species-conservation/trophic-interactions-and-habitat-requirements-gulf-mexico (``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 (https://seamap.env.duke.edu/models/Duke/EC/). 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 https://seamap.env.duke.edu/models/SEFSC/GOM/
) 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 https://www.govinfo.gov/collection/boem.
    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 
https://seamap.env.duke.edu/models/SEFSC/GOM/. 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 https://www.data.boem.gov/Main/Default.aspx). 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: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico.
    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\
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    \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: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports).
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BILLING CODE 3510-22-C
    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\ (https://www.fisheries.noaa.gov/resource/map/rices-whale-core-distribution-area-map-gis-data) (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: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico) 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: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico), 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: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico. 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: https://www.boem.gov/gommapps). 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 31513]]

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[[Page 31514]]


[GRAPHIC] [TIFF OMITTED] TR24AP24.074

BILLING CODE 3510-22-C

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\
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    \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.
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    \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 
(https://www.fisheries.noaa.gov/science-blog/successful-final-leg-gulf-mexico-marine-mammal-and-seabird-vessel-survey). 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 year (2019-2020) at two shelf break sites, including 
one central GOM site included in the previous study and one new site 
further west, offshore Corpus Christi, Texas. (Recorders were also 
deployed at a site in Mexican waters for almost 2 years (2020-2022).) 
The study objectives were to (1) determine if Rice's whales occur in 
Mexican waters and to (2) evaluate how frequently they occur at all 
three sites. Rice's whale calls were detected on 33 and 25 percent of 
days at the central and western GOM sites, respectively, with calls 
recorded throughout the year, though no distinct seasonality was 
detected. These findings reflect an increase in the frequency and 
number of detections at the central GOM site compared with the 2016-
2017 study. The authors note that these findings highlight persistence 
of Rice's whale detections at this site over multiple years, as well as 
variability among years (Soldevilla et al., 2024). Rice's whale calls 
were also detected at the site in Mexican waters. See Soldevilla et al. 
(2024) for additional discussion. The authors also describe differences 
in Rice's whale call types recorded in the eastern GOM compared with 
those recorded in the western GOM, suggesting that whales may indeed 
have a broader distribution than the northeastern GOM (Soldevilla et 
al., 2024).
    The rate of call detections throughout the year is considerably 
higher in the eastern GOM than at the central/western GOM site where 
calls were most commonly detected, with at least 8.3 calls/hour among 
four eastern GOM sites within the core habitat area over 110 deployment 
days (Rice et al., 2014) compared to 0.27 calls/hour over the 299-day 
deployment at the central/western GOM site where calls were detected 
most frequently in the 2016-2017 study. Approximately 2,000 total calls 
were detected at the central/western GOM site over 10 months in 2016-
2017, compared to more than 66,000 total detections at the eastern GOM 
deployment site over 11 months (i.e., approximately 30 times more calls 
were detected at the eastern GOM site) (Soldevilla et al., 2022). 
Although ambient noise conditions were higher at the central/western 
GOM site, thus influencing maximum detection range, accounting for this 
difference in conditions would be expected to result in only 4-8 times 
as many call detections if all other factors (including presence and 
number of whales) were consistent (versus 30 times as many detections). 
Overall, Soldevilla et al. (2022) assessed that there seem to be fewer 
whales or more sparsely spaced whales in the central/western GOM 
compared to the eastern GOM, with calls present on fewer days, lower 
call detection rates, and far fewer call detections in the central/
western GOM.
    The passive acoustic data discussed above provide evidence that 
waters 100-400 m deep in the central and western GOM are Rice's whale 
habitat and are being used by Rice's whales in all seasons. This could 
imply that the population size is larger than previously estimated, or 
it could indicate that some individual Rice's whales have a broader 
distribution in the GOM than previously understood (Soldevilla et al., 
2024). Either way, the acoustic findings,

[[Page 31524]]

combined with the low numbers of visual sightings in the central and 
western GOM, suggest that density and abundance of Rice's whales in the 
central and western GOM are less than in the core habitat in the 
northeastern GOM. Therefore, while we expect that some individual 
Rice's whales occur outside the core habitat area and/or that whales 
from the northeastern GOM core habitat area occasionally travel outside 
the area, the currently available data are not sufficient to make 
inferences about Rice's whale density and abundance in the central and 
western GOM. More research is needed to answer key questions about 
Rice's whale density, abundance, habitat use, demography, and stock 
structure in the central and western GOM.
    While these acoustic data and few confirmed sightings support the 
presence of Rice's whales in western and central GOM waters (within the 
100-400 m water depth), the information is consistent with the 
predictions of Rice's whale density modeling, on which basis NMFS 
already anticipated and evaluated the potential for and effects of 
takes of Rice's whale in western and central GOM waters, even without 
these new data. Little is known about the number of whales that may be 
present, the nature of these individuals' use of the habitat, or the 
timing, duration, or frequency of occurrence for individual whales. 
Conversely, the importance of northeastern GOM waters to Rice's whale 
recovery is very clear (Rosel et al., 2016). Ongoing efforts to target 
and manage human impacts in the northeastern core habitat are 
justified, accordingly. A comparison of acoustic and sightings data 
from the central/western and eastern GOM, even acknowledging the 
limitations of those data, suggests that occurrence of whales in the 
northeastern GOM core habitat is significantly greater and that the 
area provides the habitat of greatest importance to the species.
    Restricting survey activity in central/western GOM waters from 100-
400 m depth would avoid likely Level B harassment of any individuals 
that may occur in the area, but aside from the very large area within 
the 100-400 m isobaths throughout the GOM generally, there is no 
information supporting further delineation of any specific area within 
which a restriction on survey activity might be expected to provide 
targeted reductions in adverse impacts to Rice's whales or their 
habitat, and no such information was provided through public comment. 
Further, Level B harassment that may occur in the central/western GOM 
may be expected to have lower potential for meaningful consequences 
relative to Level B harassment events that occur in the northeastern 
GOM core habitat area, where important behavior may be more likely 
disrupted, and where greater numbers of Rice's whale are expected to 
occur. The relatively low level of take predicted for Rice's whales in 
the geographic scope for the specified activity under this final rule, 
as well as the existing mitigation measures (including expanded 
shutdowns for Rice's whales), which are expected with a high degree of 
confidence to minimize the duration and intensity of any instances of 
take that do occur, factor into NMFS' consideration of the potential 
benefits of any restriction on survey effort in central and western GOM 
waters 100-400 m depth.
    Practicability--NMFS produced a draft RIA in support of the 2018 
proposed rule, which evaluated potential costs associated with a range 
of area-based activity restrictions (available online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico). Although that 
analysis did not directly evaluate the impacts of area-based 
restrictions for Rice's whales in the central and western GOM, it did 
consider the impacts of other potential area-based restrictions, 
including seasonal and year-round restrictions in the northeastern GOM 
core habitat area for Rice's whales, and in so doing provided a useful 
framework for considering practicability of area-based restrictions 
considered in this current rulemaking. The analysis suggested that the 
analyzed seasonal and year-round area closures would have the potential 
to generate reductions in leasing, exploration, and subsequent 
development activity. Although the 2018 draft RIA cautioned that its 
conclusions were subject to substantial uncertainty, it provided 
several factors that the likelihood of ultimate impacts to oil and gas 
production as a result of delays in data collection could be expected 
to depend upon: (1) oil and gas market conditions; (2) the relative 
importance of the closure area to oil and gas production; (3) the state 
of existing data covering the area; and (4) the duration of the 
closure. For this current rulemaking, NMFS cannot predict factor (1) 
and does not have complete information regarding factor (3) (though the 
2018 draft RIA provides that new surveys are expected to be required to 
facilitate efficient exploration and development decisions). We can, 
however, more adequately predict the effects of factors (2) and (4) on 
the impact of any closure.
    Habitat that supports all of the Rice's whale life-history states 
is generally considered to consist of the aforementioned strip of 
continental shelf waters within the 100-400 m isobaths throughout the 
U.S. GOM (Roberts et al., 2016; Garrison et al. 2023; NMFS, 2023). 
Salinity and surface water velocity are likely predictive of potential 
Rice's whale occurrence (Garrison et al., 2023), but these more dynamic 
variables are less useful in delineating a potential area of importance 
than the static depth variable. Within this GOM-wide depth range, we 
focus on the area where Soldevilla et al. (2022; 2024) recorded Rice's 
whale calls as being of interest for a potential restriction. This area 
lies within the central GOM, where the vast majority of seismic survey 
effort during NMFS' experience implementing the 2021 rule has occurred. 
The 2018 proposed rule draft RIA considered the economic impacts of a 
prospective closure area in deeper waters of the central GOM. The 
evaluated area was designed to benefit sperm whales and beaked whales, 
which are found in deep water, and more activity is projected to occur 
in deep water than in the shelf-break waters where Rice's whale habitat 
occurs. As such, the 2018 draft RIA analysis likely overestimates the 
potential impacts of a central or western GOM closure within a portion 
of the shelf waters considered to be Rice's whale habitat. However, the 
draft RIA analysis of deep-water closures in the central GOM suggests 
that a central GOM closure for Rice's whales could cause significant 
economic impacts. A key consideration in this finding relates to factor 
(4), as the analyzed closure for sperm whales and beaked whales was 
year-round. Similarly, there is no information to support a temporal 
component to design of a potential Rice's whale restriction and, 
therefore, a restriction would appropriately be year-round. As 
operators have no ability to plan around a year-round restriction, this 
aspect exacerbates the potential for effects on oil and gas production 
in the GOM.
    We also considered data available specifically for the area under 
consideration (Rice's whale habitat in the central and western GOM). 
While Rice's whale habitat (i.e., water depths of 100-400 m on the 
continental shelf break) contains 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, central and western GOM waters 100-

[[Page 31525]]

400 m nevertheless host significant industry activity. BOEM provides 
summary information by water depth bin, including water depths of 201-
400 m (see https://www.data.boem.gov/Main/Default.aspx). The area 
covering those depths 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 the oil 
and gas industry typically uses targeted seismic to refine geologic 
analyses before drilling a well. During implementation of the existing 
rule, NMFS has issued (at the time of writing) 5 LOAs in association 
with surveys that partially overlapped the central GOM 100-400 m depth 
band (88 FR 68106, September 29, 2023; 88 FR 23403, April 17, 2023; 87 
FR 55790, October 1, 2022; 87 FR 43243, July 20, 2022; 87 FR 42999, 
July 19, 2022). These surveys support a conclusion that a year-round 
closure would likely substantially affect future GOM oil and gas 
activity.
    In summary, the foregoing supports that (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. 
Therefore, while new information regarding Rice's whale presence in 
areas of the GOM outside of the northeastern core habitat suggests that 
a restriction on survey effort may be expected to reduce adverse 
impacts to the species, there is a lack of information supporting the 
importance of or appropriately specific timing or location of such a 
restriction and an unclear understanding of the importance of 
particular areas to individual whales or the population as a whole. On 
the other hand, information regarding the potential for economic 
impacts resulting from a year-round restriction broadly in the 100-400 
m area supports our conclusion that there are significant 
practicability concerns. As a result, NMFS has determined that no 
additional mitigation is warranted to effect the LPAI on the species.
    NMFS has reevaluated the suite of mitigation measures required 
through the 2021 final regulations and considered other measures in 
light of the new information considered in this rule. Based on our 
evaluation of these measures, we have affirmed that the required 
mitigation measures contained in the current regulations provide the 
means of effecting the LPAI on marine mammal species or stocks and 
their habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance.

Monitoring and Reporting

    In order to issue an incidental take authorization for an activity, 
section 101(a)(5)(A) of the MMPA states that NMFS must set forth 
requirements pertaining to the monitoring and reporting of the 
authorized taking. NMFS' MMPA implementing regulations further describe 
the information that an applicant should provide when requesting an 
authorization (50 CFR 216.104 (a)(13)), including the means of 
accomplishing the necessary monitoring and reporting that will result 
in increased knowledge of the species and the level of taking or 
impacts on populations of marine mammals. Effective reporting is 
critical both to compliance as well as ensuring that the most value is 
obtained from the required monitoring.
    We have made no changes to the current LOA reporting requirements, 
which have been sufficient to date. Accordingly, the monitoring and 
reporting requirements for this rule remain identical to the 2021 final 
rule and ITR, and we refer readers back to that document (86 FR 5322, 
January 19, 2021) for the discussion.

Negligible Impact Analysis and Determinations

    NMFS' implementing regulations define negligible impact as an 
impact resulting from the specified activity that cannot be reasonably 
expected to, and is not reasonably likely to, adversely affect the 
species or stock through effects on annual rates of recruitment or 
survival (50 CFR 216.103). A negligible impact finding is based on the 
lack of likely adverse effects on annual rates of recruitment or 
survival (i.e., population-level effects). An estimate of the number of 
takes alone is not enough information on which to base a negligible 
impact determination. In addition to considering estimates of the 
number of marine mammals that might be ``taken'' by mortality, serious 
injury, and Level A or Level B harassment, we consider other factors, 
such as the type of take, the likely nature of any behavioral responses 
(e.g., intensity, duration), the context of any such responses (e.g., 
critical reproductive time or location, migration), as well as effects 
on habitat, and the likely effectiveness of mitigation. We also assess 
the number, intensity, and context of estimated takes by evaluating 
this information relative to population status. Consistent with the 
1989 preamble for NMFS' implementing regulations (54 FR 40338, 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into these analyses via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality).
    For each potential activity-related stressor, NMFS considers the 
potential effects to marine mammals and the likely significance of 
those effects to the species or stock as a whole. Potential risk due to 
vessel collision in view of the related mitigation measures, as well as 
potential risk due to entanglement and contaminant spills, were 
addressed in the Proposed Mitigation and Potential Effects of the 
Specified Activity on Marine Mammals sections of the 2018 and 2021 
notices of proposed and final rulemaking and are not discussed further, 
as there are minimal risks expected from these potential stressors.
    The ``specified activity'' for this rule continues to be a broad 
program of geophysical survey activity that could occur at any time of 
year in U.S. waters of the GOM, within the same specified geographical 
region as the 2021 final rule (i.e., updated from the 2018 proposed 
rule to exclude the former GOMESA leasing moratorium area) and for the 
same 5-year period. The acoustic exposure modeling used for the 2021 
rulemaking and for this rule provides marine mammal noise exposure 
estimates based on BOEM-provided projections of future survey effort 
and best available modeling of sound propagation, animal distribution, 
and animal movement. This information provides a best estimate of 
potential acute noise exposure events that may result from the 
described suite of activities.
    Systematic Risk Assessment Framework--In recognition of the broad 
geographic and temporal scale of this activity, in support of the 
issuance of the 2021 rule, we applied an explicit, systematic risk 
assessment framework to evaluate potential effects of aggregated 
discrete acoustic exposure events (i.e., geophysical survey activities) 
on marine mammals, which is in turn used in the negligible impact 
analysis. This risk assessment framework was described by Southall et 
al. (2017) (available online at: https://www.fisheries.noaa.gov/

[[Page 31526]]

national/marine-mammal-protection/incidental-take-authorizations-oil-
and-gas) and discussed in detail in the 2018 notice of proposed 
rulemaking. That risk assessment framework, as refined in our 2021 
final rule in response to public comment on the 2018 proposed rule and 
in consideration of the updated scope of the activity, was utilized for 
this rulemaking.
    In summary, the systematic risk assessment framework uses the 
modeling results to put into biologically-relevant context the level of 
potential risk of injury and/or disturbance to marine mammals. The 
framework considers both the aggregation of acute effects and the broad 
temporal and spatial scales over which chronic effects may occur. 
Generally, this approach is a relativistic risk assessment that 
provides an interpretation of the exposure estimates within the context 
of key biological and population parameters (e.g., population size, 
life history factors, compensatory ability of the species, animal 
behavioral state, aversion), as well as other biological, 
environmental, and anthropogenic factors. This analysis was performed 
on a species-specific basis within each modeling zone (Figure 2), and 
the end result provides an indication of the biological significance of 
the evaluated exposure numbers for each affected marine mammal stock 
(i.e., yielding the severity of impact and vulnerability of stock/
population information), and forecasts the likelihood of any such 
impact. This result is expressed as relative impact ratings of overall 
risk that couple (1) potential severity of effect on a stock, and (2) 
likely vulnerability of the population to the consequences of those 
effects, given biologically relevant information (e.g., compensatory 
ability).
    Spectral, temporal, and spatial overlaps between survey activities 
and animal distribution are the primary factors that drive the type, 
magnitude, and severity of potential effects on marine mammals, and 
these considerations are integrated into both the severity and 
vulnerability assessments. The risk assessment framework utilizes a 
strategic approach to balance the weight of these considerations 
between the two assessments, specifying and clarifying where and how 
the interactions between potential disturbance and species within these 
dimensions are evaluated.
    This risk assessment framework is one component of the negligible 
impact analysis. As we explain more below, overall risk ratings from 
that assessment are then considered in conjunction with the required 
mitigation (and any additional relevant contextual information) to 
ultimately inform our negligible impact determinations. Elements of 
this approach are subjective and relative within the context of this 
program of projected survey activity and, overall, the analysis 
necessarily requires the application of professional judgment. Please 
review the 2018 proposed and 2021 final rule notices, as well as 
Southall et al. (2017), for further detail.
    As shown in tables 5 and 6, estimated take numbers for most species 
have decreased relative to those evaluated in the notice of issuance 
for the 2021 final rule. We note that this includes the blackfish guild 
(consisting of the false killer whale, pygmy killer whale, melon-headed 
whale, and killer whale), for which species-specific take information 
is not available. Both the annual maximum and 5-year total take numbers 
for the group have decreased relative to the sum of the previous 
species-specific values (annual maxima and 5-year totals) evaluated in 
the 2021 final rule.
    As elements of the risk assessment framework are dependent on 
information related to stock abundance, we revisited the risk 
assessment methodology for all species and present updated information 
below. Specifically, as discussed below, severity ratings are the 
product of comparison between estimated take numbers and modeled 
population abundance, on a zone-specific basis. As the zone-specific 
modeled population abundance values have been updated through new 
density modeling (Garrison et al., 2023), we re-examined all severity 
ratings. The vulnerability assessment component is less directly 
dependent on population abundance information, but does incorporate 
certain species population information, including a trend rating and 
population size, as well as a factor related to species habitat use. 
With publication of new SARs information for all species, we revisited 
the former components of the vulnerability assessment, whereas the 
aforementioned updated density modeling effort provides new zone-
specific abundance values that inform the assessment of habitat use in 
each zone (i.e., proportion of GOM-wide estimated population in each 
zone).
    Estimated take numbers increased (relative to the 2021 final rule) 
for only 4 species: Rice's whale, Fraser's dolphin, rough-toothed 
dolphin, and striped dolphin (we note that overall relative risk 
ratings remained static for Rice's whale and Fraser's dolphin). The 
change in estimated take numbers for each of the 4 species within the 
blackfish category relative to the take estimates for those 4 species 
in the 2021 final rule is unknown under NMFS' approach to estimating 
take numbers. However, overall relative risk ratings increased slightly 
for most species. Of the species for which estimated take decreased, 
relative risk ratings remained static (or declined) for the sperm 
whale, beaked whales, bottlenose dolphins, and spinner dolphin. No new 
information is available for these four taxa that would suggest that 
the existing negligible impact analyses should be revisited. Therefore, 
we rely on the previous negligible impact analyses for the sperm whale, 
all beaked whale species, all bottlenose dolphin stocks, and the 
spinner dolphin. Please see the notice of issuance for the 2021 final 
rule (86 FR 5322, January 19, 2021) for analysis related to these 
species and stocks, which we incorporate here by reference.
    For those species for which evaluated take numbers increased and/or 
for which the assessed relative risk rating increased, our negligible 
impact analyses begin with the risk assessment framework, which 
comprehensively considers the aggregate impacts to marine mammal 
populations from the specified activities in the context of both the 
severity of the impacts and the vulnerability of the affected species. 
However, it does not consider the effects of the mitigation required 
through the regulations in identifying risk ratings for the affected 
species. In addition, while the risk assessment framework 
comprehensively considers the spatial and temporal overlay of the 
activities and the marine mammals in the GOM, as well as the number of 
predicted takes, there are details about the nature of any ``take'' 
anticipated to result from these activities that were not considered 
directly in the framework analysis that warrant explicit consideration 
in the negligible impact determination.
    Accordingly, following the description of the framework analysis 
presented below, NMFS highlights a few factors regarding the nature of 
the predicted ``takes,'' then synthesizes the results of implementation 
of the framework, the additional factors regarding the nature of the 
predicted takes, and the anticipated effects of the mitigation to 
consider the negligible impact determination for each of the species 
considered here. The risk assessment analysis below is performed for 2 
representative years, one representing a relatively high-effort 
scenario (Year 1 of the effective period of rule) and the other 
representing a moderate-effort scenario (Year 4 of the rule). Please 
see table 1 for details

[[Page 31527]]

regarding BOEM's level of effort projections.

Severity of Effect

    Severity ratings consider the scaled Level B harassment takes 
relative to zone-specific population abundance to evaluate the severity 
of effect. As described above in Estimated Take, a significant model 
assumption was that populations of animals were reset for each 24-hour 
period. Exposure estimates for the 24-hour period were then aggregated 
across all assumed survey days as completely independent events, 
assuming populations turn over completely within each large zone on a 
daily basis. In order to evaluate modeled daily exposures and determine 
more realistic exposure probabilities for individuals across multiple 
days, we used information on species-typical movement behavior to 
determine a species-typical offset of modeled daily exposures, 
summarized under Estimated Take (and discussed in further detail in the 
2021 notice of issuance for the final rule). Given that many of the 
evaluated survey activities occur for 30-day or longer periods, 
particularly some of the larger surveys for which the majority of the 
modeled exposures occur, this scaling process is appropriate to 
evaluate the likely severity of the predicted exposures. (For 
consideration of LOA applications, scaling is appropriate to estimate 
take and estimate the numbers of individual marine mammals likely to be 
taken (although, for surveys significantly longer than 30 days, the 
take numbers with this scaling applied would still be expected to 
overestimate the number of individuals, given the greater degree of 
repeat exposures that would be expected the longer the survey goes 
on)). This scaling output was used in a severity assessment. This 
approach is also discussed in more detail in the Southall et al. (2017) 
report.
    The scaled Level B harassment takes were then rated through a 
population-dependent binning system used to evaluate risk associated 
with behavioral disruption across species--a simple, logical means of 
evaluating relative risk across species and areas. See the notice of 
issuance for the 2021 final rule for more detail regarding the 
definition of relative risk ratings. Results of the reassessed severity 
ratings are shown in table 9.
    Level A harassment (including PTS) is not expected to occur for any 
of the species evaluated here, with the exception of Kogia spp. 
Estimated takes by Level A harassment for Kogia spp., which are 
discussed in further detail below, declined relative to what was 
evaluated in the 2021 final rule. See tables 5 and 6.
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Vulnerability of Affected Population

    Vulnerability rating seeks to evaluate the relative risk of a 
predicted effect given species-typical and population-specific 
parameters (e.g., species-specific life history, population factors) 
and other relevant interacting factors (e.g., human or other 
environmental stressors). The assessment includes consideration of four 
categories within two overarching risk factors (species-specific 
biological and environmental risk factors). These values were selected 
to capture key aspects of the importance of spatial (geographic), 
spectral (frequency content of noise in relation to species-typical 
hearing and sound communications), and temporal relationships between 
sound and receivers. Explicit numerical criteria for identifying scores 
were specified where possible, but in some cases qualitative judgments, 
based on a reasonable interpretation of given aspects of the

[[Page 31528]]

specified activity and how it relates to the species in question and 
the environment within the specified area, were required. The 
vulnerability assessment includes factors related to population status, 
habitat use and compensatory ability, masking, and other stressors. 
These factors were detailed in Southall et al. (2017) and discussed in 
further detail in the notice of issuance for the 2021 final rule. 
Please see that notice for further detail regarding these aspects of 
the framework and for definitions of vulnerability ratings. Note that 
the effects of the DWH oil spill are accounted for through a non-noise 
chronic anthropogenic risk factor, while the effects to acoustic 
habitat and on individual animal behavior via masking are accounted for 
through the masking and chronic anthropogenic noise risk factors. The 
results of reassessed species-specific vulnerability scoring are shown 
in table 10. Note that, as there are certain species-specific elements 
of the vulnerability assessment, we evaluated each of the four species 
contained within the blackfish group. For purposes of evaluating 
relative risk, we assume that the greatest vulnerability (assessed for 
melon-headed whale) applies to each species in the blackfish group.
[GRAPHIC] [TIFF OMITTED] TR24AP24.079

Risk Ratings

    In the final step of the framework, severity and vulnerability 
ratings are integrated to provide relative impact ratings of overall 
risk, i.e., relative risk ratings. Severity and vulnerability 
assessments each produce a numerical rating (1-5) corresponding with 
the qualitative rating (i.e., very low, low, moderate, high, very 
high). A matrix is then used to integrate these two scores to provide 
an overall risk assessment rating for each species. The matrix is shown 
in table 2 of Southall et al. (2017).
    Table 11 provides relative impact ratings for overall risk by zone 
and activity effort scenario (high and moderate), and table 12 provides 
GOM-wide relative impact ratings for overall risk for representative 
high and moderate effort scenarios.
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[[Page 31530]]


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    In order to characterize the relative risk for each species across 
their entire range in the GOM, we used the median of the seven zone-
specific risk ratings for each activity scenario (high and moderate 
effort), not counting those in which less than 0.05 percent of the GOM-
wide abundance occurred (``n/a'' in table 11), to describe a GOM-wide 
risk rating for each of the representative activity scenarios (table 
12).
    As noted above, for sperm whale, beaked whales, bottlenose 
dolphins, and spinner dolphin, estimated take numbers decreased and 
relative risk ratings remained static (or decreased) compared with the 
2021 final rule. Therefore, we rely on the analysis provided in the 
notice of issuance for the 2021 final rule for those species and 
stocks, which are not discussed further here.
    Overall, the results of the risk assessment show that (as expected) 
risk is highly correlated with effort and density. Areas where little 
or no survey activity is predicted to occur or areas within which few 
or no animals of a particular species are believed to occur generally 
have very low or no potential risk of negatively affecting marine 
mammals, as seen across activity scenarios in Zones 1-4 (no activity 
will occur in Zone 1, which was entirely removed from scope of the 
rule, and less than 2 percent of Zone 4 remains within scope of the 
rule). Fewer species are expected to be present in Zones 1-3, where 
only bottlenose and Atlantic spotted dolphins occur in meaningful 
numbers. Areas with consistently high projected levels of effort (Zones 
5-7) are generally predicted to have higher overall evaluated risk 
across all species. In Zone 7, animals are expected to be subject to 
less other chronic noise and non-noise stressors, which is reflected in 
the vulnerability scoring for that zone. Therefore, despite 
consistently high levels of projected effort, overall rankings for Zone 
7 are lower than for Zones 5 and 6.
    A ``high'' level of relative risk due to behavioral disturbance was 
identified in Zone 5 under both scenarios for most of the species 
evaluated further below (excepting Rice's whale (both scenarios) and 
Kogia spp., Atlantic spotted dolphin, and short-finned pilot whale 
(moderate effort scenario only)). ``High'' relative risk was not 
identified under either scenario in any other zone for any

[[Page 31531]]

species (and ``very high'' relative risk was not identified under 
either scenario in any zone for any of the species evaluated further 
below). Overall, the greatest relative risk across species is generally 
seen in Zone 5 (both scenarios) and in Zone 6 (under the high effort 
scenario).
    Changes to relative risk ratings may be seen by comparing table 12 
above with table 15 from the 2021 final rule, and changes (in numerical 
terms) are indicated in parentheses for each scenario. All increases to 
assessed relative risk represent minor changes, i.e., if considered as 
a numerical scale (with ``very low'' = 1 and ``very high'' = 5), with 
one exception, there was no risk rating increase greater than one 
point. As noted above, despite increases in estimated take numbers, 
relative risk ratings for Rice's whale and Fraser's dolphin remained 
static. In the 2021 final rule, all 4 species comprising the blackfish 
group were individually assessed as having ``very low'' relative risk 
under both scenarios. In this analysis, the blackfish as a group are 
assessed as having relative risk between ``low'' and ``moderate'' under 
the high effort scenario (representing the lone example of a 1.5 point 
increase) and ``low'' under the moderate effort scenario.
    Although the scores generated by the risk assessment framework and 
further aggregated across zones (as described above) are species-
specific, additional stock-specific information is also considered in 
our analysis, where appropriate, as indicated in the Description of 
Marine Mammals in the Area of the Specified Activity, Potential Effects 
of the Specified Activity on Marine Mammals and Their Habitat, and 
Mitigation sections of the 2018 notice of proposed rulemaking, 2021 
final rule, 2023 notice of proposed rulemaking, and this action.

Duration of Level B Harassment Exposures

    In order to more fully place the predicted amount of take into 
meaningful context, it is useful to understand the duration of exposure 
at or above a given level of received sound, as well as the likely 
number of repeated exposures across days. While any exposure above the 
criteria for Level B harassment counts as an instance of take, that 
accounting does not make any distinction between fleeting exposures and 
more severe encounters in which an animal may be exposed to that 
received level of sound for a longer period of time. Yet, this 
information is meaningful to an understanding of the likely severity of 
the exposure, which is relevant to the negligible impact evaluation and 
not directly incorporated into the risk assessment framework. Each 
animat modeled has a record or time history of received levels of sound 
over the course of the modeled 24-hour period. For example, for the 4 
blackfish species exposed to noise from 3D WAZ surveys, the 50th 
percentile of the cumulative distribution function indicates that the 
time spent exposed to levels of sound above 160 dB rms SPL (i.e., the 
50 percent midpoint for Level B harassment) would range from only 1.4 
to 3.3 minutes--a minimal amount of exposure carrying little potential 
for significant disruption of behavioral activity. We provide summary 
information for the species evaluated here regarding the total average 
time in a 24-hour period that an animal would spend with received 
levels above 160 dB (the threshold at which 50 percent of the exposed 
population is considered taken) and between 140 and 160 dB (where 10 
percent of the exposed population is considered taken) in table 13. 
This information considered is unchanged from the 2021 final rule.
    Additionally, as we discussed in the Estimated Take section of the 
2018 notice of proposed rulemaking for Test Scenario 1 (and summarized 
above), by comparing exposure estimates generated by multiplying 24-
hour exposure estimates by the total number of survey days versus 
modeling for a full 30-day survey duration for 6 representative 
species, we were able to refine the exposure estimates to better 
reflect the number of individuals exposed above threshold within a 
single survey. Using this same comparison and scalar ratios described 
above, we are able to predict an average number of days each of the 
representative species modeled in the test scenario were exposed above 
the Level B harassment thresholds within a single survey. As with the 
duration of exposures discussed above, the number of repeated exposures 
is important to an understanding of the severity of effects. For 
example, the ratio for dolphins indicates that the 30-day modeling 
showed that approximately 29 percent as many individual dolphins 
(compared to the results produced by multiplying average 24-hour 
exposure results by the 30-day survey duration) could be expected to be 
exposed above harassment thresholds. However, the approach of scaling 
up the 24-hour exposure estimates appropriately reflects the instances 
of exposure above threshold (which cannot be more than 1 in 24 hours), 
so the inverse of the scalar ratio suggests the average number of days 
in the 30-day modeling period that dolphins are exposed above threshold 
is approximately 3.5. It is important to remember that this is an 
average within a given survey, and that it is more likely some 
individuals would be exposed on fewer days and some on more. table 13 
reflects the average days exposed above threshold for the indicated 
species after the scalar ratios were applied.
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Loss of Hearing Sensitivity

    In general, NMFS expects that noise-induced hearing loss as a 
result of airgun survey activity, whether temporary (temporary 
threshold shift, equivalent to Level B harassment) or permanent (PTS, 
equivalent to Level A harassment), is only possible for low-frequency 
and high-frequency cetaceans. The best available scientific information 
indicates that low-frequency cetacean species (i.e., mysticete whales, 
including the Rice's whale) have heightened sensitivity to frequencies 
in the range output by airguns, as shown by their auditory weighting 
function, whereas high-frequency cetacean species (including Kogia 
spp.) have heightened sensitivity to noise in general (as shown by 
their lower threshold for the onset of PTS) (NMFS, 2018). However, no 
instances of Level A harassment are predicted to occur for Rice's 
whales, and none may be authorized in any LOAs issued under this rule.
    Level A harassment is predicted to occur for Kogia spp. (as 
indicated in table 6). However, the degree of injury (hearing 
impairment) is expected to be mild. If permanent hearing impairment 
occurs, it is most likely that the affected animal would lose a few dB 
in its hearing sensitivity, which in most cases would not be expected 
to affect its ability to survive and reproduce. Hearing impairment that 
occurs for these individual animals would be limited to at or slightly 
above the dominant frequency of the noise sources. In particular, the 
predicted PTS resulting from airgun exposure is not likely to affect 
their echolocation performance or communication, as Kogia spp. likely 
produce acoustic signals at frequencies above 100 kHz (Merkens et al., 
2018), well above the frequency range of airgun noise. Further, modeled 
exceedance of Level A harassment criteria typically resulted from being 
near an individual source once, rather than accumulating energy from 
multiple sources. Overall, the modeling indicated that exceeding the 
SEL threshold for PTS is a rare event, and having 4 vessels close to 
each other (350 m between tracks) did not cause appreciable 
accumulation of energy at the ranges relevant for injury exposures. 
Accumulation of energy from independent surveys is expected to be 
negligible. This is relevant for Kogia spp. because based on their 
expected sensitivity, we expect that aversion may play a stronger role 
in avoiding exposures above the peak pressure PTS threshold than we 
have accounted for.
    Some subset of the individual marine mammals predicted to be taken 
by Level B harassment may incur some TTS. For Rice's whales, TTS may 
occur at frequencies important for communication. However, any TTS 
incurred would be expected to be of a relatively small degree and short 
duration. This is due to the low likelihood of sound source approaches 
of the proximity or duration necessary to cause more severe TTS, given 
the fact that both sound source and marine mammals are continuously 
moving, the anticipated effectiveness of shutdowns, and general 
avoidance by marine mammals of louder sources.
    For these reasons, and in conjunction with the required mitigation, 
NMFS does not believe that Level A harassment (here, PTS) or Level B 
harassment in the form of TTS will play a meaningful role in the 
overall degree

[[Page 31533]]

of impact experienced by marine mammal populations as a result of the 
projected survey activity. Further, the impacts of any TTS incurred are 
addressed through the broader analysis of Level B harassment.

Impacts to Habitat

    Potential impacts to marine mammal habitat, including to marine 
mammal prey, were discussed in detail in the 2018 notice of proposed 
rulemaking as well as in the 2021 notice of issuance for the final 
rule, including in responses to comments concerning these issues (83 FR 
29212, 29241, June 22, 2018; 86 FR 5322, 5335, January 19, 2021). There 
is no new information that changes that assessment, and we rely on the 
assessment provided in those documents and reiterated below.
    Regarding impacts to prey species such as fish and invertebrates, 
NMFS' review of the available information leads to a conclusion that 
the most likely impact of survey activity would be temporary avoidance 
of an area, with a rapid return to pre-survey distribution and 
behavior, and minimal impacts to recruitment or survival anticipated. 
Therefore, the specified activities are not likely to have more than 
short-term adverse effects on any prey habitat or populations of prey 
species. Further, any impacts to prey species are not expected to 
result in significant or long-term consequences for individual marine 
mammals, or to contribute to adverse impacts on their populations.
    Regarding potential impacts to acoustic habitat, NMFS provided a 
detailed analysis of potential cumulative and chronic effects to marine 
mammals (found in the Cumulative and Chronic Effects report, available 
online at https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico). See also 83 FR 29212, 29242 (June 22, 2018) for detailed 
discussion of acoustic habitat. That analysis focused on potential 
effects to the acoustic habitat of sperm whales and Rice's whales via 
an assessment of listening and communication space. The analysis 
performed for sperm whales (which provides a useful proxy for other 
mid- and high-frequency cetaceans evaluated here) shows that the survey 
activities do not significantly contribute to the soundscape in the 
frequency band relevant for their lower-frequency slow-clicks and that 
there will be no significant change in communication space for sperm 
whales. Similar conclusions may be assumed for other mid- and high-
frequency cetacean species.
    Implications for acoustic masking and reduced communication space 
resulting from noise produced by airgun surveys in the GOM are expected 
to be particularly heightened for animals that actively produce low-
frequency sounds or whose hearing is attuned to lower frequencies 
(i.e., Rice's whales). The strength of the communication space approach 
used here is that it evaluates potential contractions in the 
availability of a signal of documented importance. In this case, losses 
of communication space for Rice's whales were estimated to be higher in 
western and central GOM canyons and shelf break areas. In contrast, 
relative maintenance of listening area and communication space was seen 
within the Rice's whale core habitat area in the northeastern GOM. The 
result was heavily influenced by the projected lack of survey activity 
in that region, which underscores the importance of maintaining the 
acoustic soundscape of this important habitat for the Rice's whale. In 
light of BOEM's 2020 update to the scope of the specified activity, no 
survey activity will occur under this rule within the Rice's whale core 
habitat area or within the broader eastern GOM. See Figures 3-4. In 
deepwater areas where larger amounts of survey activity were projected, 
significant loss of low-frequency listening area and communication 
space was predicted by the model, but this finding was discounted 
because Rice's whales are less likely to occur in deeper waters of the 
central and western GOM.

Species-Specific Negligible Impact Analysis Summaries

    In this section, for the species evaluated herein (i.e., all but 
sperm whale, beaked whales, bottlenose dolphin, and spinner dolphin, 
for which, as described previously, we incorporate by reference the 
analysis conducted in the 2018 rule), we consider the relative impact 
ratings described above in conjunction with the required mitigation and 
other relevant contextual information in order to produce a final 
assessment of impact to the species or stocks, i.e., the negligible 
impact determinations. The effects of the DWH oil spill are accounted 
for through the vulnerability scoring (table 10).
    Although Rice's whale core habitat in the northeastern GOM is not 
the subject of restrictions on survey activity, as the scope of the 
specified activity does not include the area (see Figures 3-4), the 
beneficial effect for the species remains the same. The absence of 
survey activity in the eastern GOM (see Figure 2) benefits GOM marine 
mammals by reducing the portion of a stock likely exposed to survey 
noise and avoiding impacts to certain species in areas of importance 
for them. Habitat areas of importance in the eastern GOM are discussed 
in detail in the Proposed Mitigation section of the 2018 notice of 
proposed rulemaking.

Rice's Whale

    The risk assessment analysis, which evaluated the relative 
significance of the aggregated impacts of the survey activities across 
seven GOM zones in the context of the vulnerability of each species, 
concluded that the GOM-wide risk ratings for Rice's whales are low, 
regardless of activity scenario. We note that, although the evaluated 
severity of take for Rice's whales is very low in all zones where take 
could occur, vulnerability for the species is assessed as high in 5 of 
the 6 zones where the species occurs (vulnerability is assessed as 
moderate in Zone 3, where less than 1 percent of GOM-wide abundance is 
predicted to occur). When integrated through the risk framework 
described above, overall risk for the species is therefore assessed as 
low for both the high and moderate effort scenarios. The evaluated risk 
rating is the same as what was considered in the 2021 notice of 
issuance of the final rule, despite increased take numbers (see tables 
5-6). In the context of what remain relatively low predicted take 
numbers, the relative risk ratings for the species remain driven by the 
assessed vulnerability.
    We further consider the likely severity of any predicted behavioral 
disruption of Rice's whales in the context of the likely duration of 
exposure above Level B harassment thresholds. Specifically, the average 
modeled time per day spent at received levels above 160 dB rms (the 
threshold at which 50 percent of the exposed population is considered 
taken) ranges from 6.8-21.4 minutes for deep penetration survey types. 
The average time spent exposed to received levels between 140 and 160 
dB rms (where 10 percent of the exposed population is considered taken) 
ranges from 55-164 minutes for 2D, 3D NAZ, and 3D WAZ surveys, and 401 
minutes for coil surveys (which comprise approximately 10 percent of 
the total activity days).
    Importantly, no survey activity will occur within the eastern GOM 
pursuant to this rule. Although there is new evidence of Rice's whale 
occurrence in the central and western GOM from passive acoustic 
detections (Soldevilla et al., 2022; 2024), the highest densities of 
Rice's whales remain confined to the northeastern GOM core habitat (see

[[Page 31534]]

Figures 3-4). Moreover, the number of individuals that occur in the 
central and western GOM and nature of their use of this area is poorly 
understood. Soldevilla et al. (2022) suggest that more than one 
individual was present on at least one occasion, as overlapping calls 
of different call subtypes were recorded in that instance, but also 
state that call detection rates suggest that either multiple 
individuals are typically calling or that individual whales are 
producing calls at higher rates in the central/western GOM. Soldevilla 
et al. (2024) provide further evidence that Rice's whale habitat 
encompasses all 100-400 m depth waters encircling the entire GOM 
(including Mexican waters), but they also note that further research is 
needed to understand the density of whales in these areas, seasonal 
changes in whale density, and other aspects of habitat usage.
    This new information does not affect the prior conclusion that the 
absence of survey activity in the eastern GOM benefits Rice's whales 
and their habitat by minimizing a range of potential effects of airgun 
noise, both acute and chronic, that could otherwise accrue to impact 
the reproduction or survival of individuals in this area, and that the 
absence of survey activity in the eastern GOM will minimize disturbance 
of the species in the place most important to them for critical 
behaviors such as foraging and socialization. The absence of survey 
activity in this area and significant reduction in associated exposures 
of Rice's whales to seismic airgun noise is expected to eliminate the 
likelihood of auditory injury of Rice's whales. Finally, the absence of 
survey activity in the eastern GOM will reduce chronic exposure of 
Rice's whales to higher levels of anthropogenic sound and the 
associated effects including masking, disruption of acoustic habitat, 
long-term changes in behavior such as vocalization, and stress.
    As described in the preceding Loss of Hearing Sensitivity section, 
we have analyzed the likely impacts of potential temporary hearing 
impairment and do not expect that they would result in impacts on 
reproduction or survival of any individuals. The extended shutdown zone 
for Rice's whales (1,500 m)--to be implemented in the unlikely event 
that a Rice's whale is encountered--is expected to further minimize the 
severity of any hearing impairment incurred as well as reduce the 
likelihood of more severe behavioral responses.
    The estimated take numbers for Rice's whale in this final rule are 
higher than those considered in the 2021 final rule (see tables 5-6). 
Accordingly, NMFS re-evaluated the relative risk rating for Rice's 
whale (tables 11-12), and considered other relevant information for the 
species. As discussed above, the risk ratings did not change from those 
assessed in the 2021 final rule, and new information considered herein 
does not affect the determinations previously made in that analysis. No 
mortality of Rice's whales is anticipated or authorized. It is possible 
that Rice's whale individuals, if encountered, will be taken briefly on 
one or more days during a year of activity by one type of survey or 
another and some subset of those exposures above thresholds may be of 
comparatively long duration within a day. However, the amount of take 
remains low (annual average of 26, with a maximum in any year of 30), 
and the significant and critical functional protection afforded through 
the absence of survey activity in the species' northeastern GOM core 
habitat and the extended shutdown requirement means that the impacts of 
the expected takes from these activities are not likely to impact the 
reproduction or survival of any individual Rice's whales, much less 
adversely affect the species through impacts on annual rates of 
recruitment or survival. Accordingly, we conclude the taking from the 
specified activity will have a negligible impact on Rice's whales as a 
species.

Kogia spp.

    The risk assessment analysis, which evaluated the relative 
significance of the aggregated impacts of the survey activities across 
seven GOM zones in the context of the vulnerability of each species, 
concluded that the GOM-wide risk ratings for Kogia spp. were between 
low and moderate (for the high effort scenario) and between very low 
and low (for the moderate effort scenario). Evaluated risk is slightly 
increased from the 2021 final rule, with modeled decreases in zone-
specific population abundance offsetting decreases in estimated take. 
We further consider the likely severity of any predicted behavioral 
disruption of Kogia spp. in the context of the likely duration of 
exposure above Level B harassment thresholds. Specifically, the average 
modeled time per day spent at received levels above 160 dB rms (where 
50 percent of the exposed population is considered taken) ranges from 
2.8-7.9 minutes for 2D, 3D NAZ, and 3D WAZ surveys and up to 15.3 
minutes for coil surveys (which comprise less than 10 percent of the 
total projected activity days), and the average time spent between 140 
and 160 dB rms (where 10 percent of the exposed population is 
considered taken) is 6.7-19 minutes.
    Odontocetes echolocate to find prey, and while there are many 
different strategies for hunting, one common pattern, especially for 
deeper diving species, is to conduct multiple repeated deep dives 
within a feeding bout, and multiple bouts within a day, to find and 
catch prey. While exposures of the short durations noted above could 
potentially interrupt a dive or cause an individual to relocate to 
feed, such a short-duration interruption would be unlikely to have 
significant impacts on an individual's energy budget and, further, for 
these species and this open-ocean area, there are no specific known 
reasons (i.e., these species range GOM-wide beyond the continental 
slope and there are no known biologically important areas) to expect 
that there would not be adequate alternate feeding areas relatively 
nearby, especially considering the anticipated absence of survey 
activity in the eastern GOM. Importantly, the absence of survey 
activity in the eastern GOM will reduce disturbance of Kogia spp. in 
places of importance to them for critical behaviors such as foraging 
and socialization and, overall, help to reduce impacts to the species 
as a whole.
    NMFS has analyzed the likely impacts of potential hearing 
impairment, including the estimated upper bounds of permanent threshold 
shift (Level A harassment) that could be authorized under the rule and 
do not expect that they would result in impacts on reproduction or 
survival of any individuals. As described in the previous section, the 
degree of injury for individuals would be expected to be mild, and the 
predicted PTS resulting from airgun exposure is not likely to affect 
echolocation performance or communication for Kogia spp. Additionally, 
the extended distance shutdown zone for Kogia spp. (1,500 m) is 
expected to further minimize the severity of any hearing impairment 
incurred and also to further reduce the likelihood of, and minimize the 
severity of, more severe behavioral responses.
    Of note, due to their pelagic distribution, small size, and cryptic 
behavior, pygmy sperm whales and dwarf sperm whales are rarely sighted 
during at-sea surveys and difficult to distinguish when visually 
observed in the field. Accordingly, abundance estimates in NMFS SARs 
are recorded for Kogia spp. only, density and take estimates in this 
rule are similarly lumped for the two species, and there is no 
additional information by which NMFS could appropriately apportion 
impacts other than equally/proportionally across the two species.

[[Page 31535]]

    No mortality of Kogia spp. is anticipated or authorized. While it 
is likely that the majority of the individuals of these two species 
will be impacted briefly on one or more days during a year of activity 
by one type of survey or another, based on the nature of the individual 
exposures and takes, as well as the aggregated scale of the impacts 
across the GOM, and in consideration of the mitigation discussed here, 
the impacts of the expected takes from these activities are not likely 
to impact the reproduction or survival of any individuals, much less 
adversely affect the GOM stocks of dwarf or pygmy sperm whales through 
impacts on annual rates of recruitment or survival. Accordingly, we 
conclude the taking from the specified activity will have a negligible 
impact on GOM stocks of dwarf or pygmy sperm whales.

Other Stocks

    In consideration of the similarities in the nature and scale of 
impacts, we consider the GOM stocks of the following species together 
in this section: rough-toothed dolphin, Clymene dolphin, Atlantic 
spotted dolphin, pantropical spotted dolphin, striped dolphin, Fraser's 
dolphin, Risso's dolphin, melon-headed whale, pygmy killer whale, false 
killer whale, killer whale, and short-finned pilot whale. With the 
exception of Fraser's dolphin, rough-toothed dolphin, and striped 
dolphin, estimated (and allowable) take of these stocks (including both 
the maximum annual take and the total take over 5 years) is lower as 
compared to the 2021 final rule.
    The risk assessment analysis, which evaluated the relative 
significance of the aggregated impacts of the survey activities across 
seven GOM zones in the context of the vulnerability of each species, 
concluded that the GOM-wide risk ratings for high and moderate effort 
scenarios ranged from very low to between low and moderate for these 
species. For the Fraser's dolphin, evaluated risk is the same as what 
was considered in the 2021 final rule, despite increased take numbers 
(see tables 5-6).
    We further considered the likely severity of any predicted 
behavioral disruption of the individuals of these species in the 
context of the likely duration of exposure above Level B harassment 
thresholds. Specifically, the average modeled time per day spent at 
received levels above 160 dB rms (where 50 percent of the exposed 
population is considered taken) ranges from 1.4-11.7 minutes for 2D, 3D 
NAZ, and 3D WAZ surveys and up to 25.7 minutes for coil surveys (which 
comprise less than 10 percent of the total projected activity days). 
The average time per day spent between 140 and 160 dB rms for 
individuals that are taken is from 8-58.1 minutes, with the one 
exception of killer whales exposed to noise from coil surveys, which 
average 73.6 minutes (though we note that the overall risk rating for 
the blackfish group, including killer whales, is low).
    Odontocetes echolocate to find prey, and there are many different 
strategies for hunting. One common pattern for deeper-diving species is 
to conduct multiple repeated deep dives within a feeding bout, and 
multiple bouts within a day, to find and catch prey. While exposures of 
the shorter durations noted above could potentially interrupt a dive or 
cause an individual to relocate to feed, such a short-duration 
interruption would be unlikely to have significant impacts on an 
individual's energy budget and, further, for these species and this 
open-ocean area, there are no specific known reasons (i.e., these 
species range GOM-wide beyond the continental slope and there are no 
known biologically important areas) to expect that there would not be 
adequate alternate feeding areas relatively nearby, especially 
considering the anticipated absence of survey activity in the eastern 
GOM. For those species that are more shallow feeding species, it is 
likely that the noise exposure considered herein would result in 
minimal significant disruption of foraging behavior and, therefore, the 
corresponding energetic effects would similarly be minimal.
    Of note, the Atlantic spotted dolphin is expected to benefit (via 
lessening of both number and severity of takes) from the coastal waters 
time-area restriction developed to benefit bottlenose dolphins, and 
several additional species can be expected to benefit from the absence 
of survey activity in important eastern GOM habitat.
    No mortality or Level A harassment of these species is anticipated 
or authorized. It is likely that the majority of the individuals of 
these species will be impacted briefly on one or more days during a 
year of activity by one type of survey or another. Based on the nature 
of the individual exposures and takes, as well as the very low to low 
aggregated scale of the impacts across the GOM and considering the 
mitigation discussed here, the impacts of the expected takes from these 
activities are not likely to impact the reproduction or survival of any 
individuals, much less adversely affect the GOM stocks of any of these 
12 species through impacts on annual rates of recruitment or survival. 
Accordingly, we conclude the taking from the specified activity will 
have a negligible impact on GOM stocks of these 12 species.

Determination

    Based on the analysis contained herein, and the analysis presented 
in the 2021 final rule for the other species and stocks for which take 
is authorized (table 6), of the likely effects of the specified 
activities on marine mammals and their habitat, and taking into 
consideration the implementation of the mitigation and related 
monitoring measures, NMFS finds that the total marine mammal take from 
the specified activities for the 5-year period of the regulations will 
have a negligible impact on all affected marine mammal species and 
stocks.

Small Numbers

    For reference, we summarize how NMFS interprets and applies the 
small numbers standard, which is substantively unchanged from the full 
discussion provided in the 2018 notice of proposed rulemaking. 
Additional discussion was provided in the Comments and Responses 
section of the notice of issuance for the 2021 final rule to address 
specific comments, questions, or recommendations received from the 
public.
    In summary, when quantitative take estimates of individual marine 
mammals are available or inferable through consideration of additional 
factors, and the number of animals taken is one-third or less of the 
best available abundance estimate for the species or stock, NMFS 
considers it to be of small numbers. For additional discussion, please 
see NMFS' notice of issuance for the 2021 final rule (86 FR 5322, 
January 19, 2021; see 86 FR 5363, 86 FR 5438). NMFS may also 
appropriately find that one or two predicted group encounters will 
result in small numbers of take relative to the range and distribution 
of a species, regardless of the estimated proportion of the abundance.
    Our 2021 final rule also concluded that NMFS may appropriately 
elect to make a ``small numbers'' finding based on the estimated annual 
take in individual LOAs issued under the rule. This approach does not 
affect the negligible impact analysis for a rule, which is the 
biologically relevant inquiry and based on the total annual estimated 
taking for all activities the regulations will govern over the 5-year 
period. NMFS determined this approach is a permissible interpretation 
of the relevant MMPA provisions.

[[Page 31536]]

    For this rule, as in the 2021 final rule, up-to-date species 
information is available, and sophisticated models have been used to 
estimate take in a manner that will allow for quantitative comparison 
of the take of individuals versus the best available abundance 
estimates for the species or guilds. Specifically, while the modeling 
effort utilized for this rule enumerates the estimated instances of 
takes that will occur across days as the result of the operation of 
certain survey types in certain areas, the modeling report also 
includes the evaluation of a test scenario that allows for a reasonable 
modification of those generalized take estimates to better estimate the 
number of individuals that will be taken within one survey (as 
discussed under Estimated Take). Use of modeling results from the rule 
allows one to reasonably approximate the number of marine mammal 
individuals taken in association with survey activities. The estimated 
take of marine mammals for each species or guild will then be compared 
against the best available abundance estimate as determined, and 
estimates that do not exceed one-third of that estimate will be 
considered small numbers.
    Our 2021 final rule contained a fuller explanation of this 
interpretation and application of ``small numbers'' and explained how 
small numbers would be evaluated under the rule. We make no changes to 
our treatment of the small numbers standard in this rule, as the new 
information considered herein has no bearing on those discussions. See 
the Small Numbers section of the 2021 final rule at 86 FR 5438-5440 and 
responses to comments on small numbers at 86 FR 5363-5368 (January 19, 
2021).

Adaptive Management

    The regulations governing the take of marine mammals incidental to 
geophysical survey activities contain an adaptive management component. 
We make no changes here. The comprehensive reporting requirements 
(described in detail in the Monitoring and Reporting section of NMFS' 
notice of issuance for the 2021 final rule (86 FR 5322, January 19, 
2021)) are designed to provide NMFS with monitoring data from the 
previous year to allow consideration of whether any changes are 
appropriate. The use of adaptive management allows NMFS to consider new 
information from different sources to determine (with input from the 
LOA-holders regarding practicability) on a regular (e.g., annual or 
biennial) basis if mitigation or monitoring measures should be modified 
(including additions or deletions). Mitigation measures could be 
modified if new data suggest that such modifications would have a 
reasonable likelihood of reducing adverse effects to marine mammal 
species or stocks or their habitat and if the measures are practicable. 
The adaptive management process and associated reporting requirements 
would serve as the basis for evaluating performance and compliance. As 
no changes to the existing adaptive management process have been made, 
we do not repeat discussion provided in the notice of issuance of the 
final rule. Please see that document for further detail.
    Under this rule, NMFS plans to continue to implement an annual 
adaptive management process including BOEM, the Bureau of Safety and 
Environmental Enforcement (BSEE), industry operators (including 
geophysical companies as well as exploration and production companies), 
and others as appropriate. Industry operators may elect to be 
represented in this process by their respective trade associations. 
NMFS, BOEM, and BSEE (i.e., the regulatory agencies) and industry 
operators who have conducted or contracted for survey operations in the 
GOM in the prior year (or their representatives) will provide an 
agreed-upon description of roles and responsibilities, as well as 
points of contact, in advance of each year's adaptive management 
process. The foundation of the adaptive management process is the 
annual comprehensive reports produced by LOA-holders (or their 
representatives), as well as the results of any relevant research 
activities, including research supported voluntarily by the oil and gas 
industry and research supported by the Federal government.
    All reporting requirements have been complied with under the rule 
to date. NMFS has received two annual reports compiled by industry 
trade associations in order to comply with the comprehensive reporting 
requirements. These reports, which consider LOA-specific reports 
received during the first and second years of implementation of the 
rule, are available online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico.

Monitoring Contribution Through Other Research

    NMFS' MMPA implementing regulations require that applicants for 
incidental take authorizations describe the suggested means of 
coordinating research opportunities, plans, and activities relating to 
reducing incidental taking and evaluating its effects (50 CFR 216.104 
(a)(14)). Such coordination can serve as an effective supplement to the 
monitoring and reporting required pursuant to issued LOAs and/or 
incidental take regulations. NMFS expects that relevant research 
efforts will inform the annual adaptive management process described 
above, and that levels and types of research efforts will change from 
year to year in response to identified needs and evolutions in 
knowledge, emerging trends in the economy and available funding, and 
available scientific and technological resources. In the 2018 notice of 
proposed rulemaking, NMFS described examples of relevant research 
efforts (83 FR 29300-29301, June 22, 2018). We do not repeat that 
information here, but refer the reader to that notice for more 
information. The described efforts may not be predictive of any future 
levels and types of research efforts. Research occurring in locations 
other than the GOM may be relevant to understanding the effects of 
geophysical surveys on marine mammals or marine mammal populations or 
the effectiveness of mitigation. NMFS also refers the reader to the 
industry Joint Industry Program (JIP) website (https://www.soundandmarinelife.org), which hosts a database of available 
products funded partially or fully through the JIP, and to BOEM's 
Environmental Studies Program (ESP), which develops, funds, and manages 
scientific research to inform policy decisions regarding outer 
continental shelf resource development (https://www.boem.gov/studies).

Impact on Availability of Affected Species for Taking for Subsistence 
Uses

    There are no relevant subsistence uses of marine mammals implicated 
by these actions. Therefore, as with the 2021 final rule, NMFS has 
determined that the total taking of affected species or stocks will not 
have an unmitigable adverse impact on the availability of such species 
or stocks for taking for subsistence purposes.

Endangered Species Act (ESA)

    Section 7 of the ESA requires Federal agencies to insure that their 
actions are not likely to jeopardize the continued existence of 
endangered or threatened species or adversely modify or destroy their 
designated critical habitat. Federal agencies must consult with NMFS 
for actions that may affect such species under NMFS' jurisdiction or 
critical habitat designated for such species. At the conclusion of 
consultation, the consulting agency provides an opinion stating whether 
the Federal agency's

[[Page 31537]]

action is likely to jeopardize the continued existence of ESA-listed 
species or destroy or adversely modify designated critical habitat.
    On March 13, 2020, NMFS' Office of Protected Resources, ESA 
Interagency Cooperation Division, issued a Biological Opinion (BiOp) on 
federally regulated oil and gas program activities in the Gulf of 
Mexico, including NMFS' issuance of the ITR and subsequent LOAs (as 
well as all BOEM and Bureau of Safety and Environmental Enforcement 
approvals of activities associated with the OCS oil and gas program in 
the GOM). The 2020 BiOp concluded that NMFS' proposed action was not 
likely to jeopardize the continued existence of sperm whales or Rice's 
whales. Of note, that BiOp evaluated the larger scope of survey 
activity originally contemplated for the rule, before BOEM revised the 
scope of its activity to remove the GOMESA area in the eastern GOM. The 
take estimates evaluated for this rule are, therefore, within the scope 
of take considered in the BiOp and do not reveal effects of the action 
that may affect listed species or critical habitat in a manner or to an 
extent not previously considered. Thus, for this rule to consider 
corrected take estimates and other newly available information, NMFS 
has determined that re-initiation of consultation is not triggered 
under 50 CFR 402.16, although NMFS does anticipate amending the 
incidental take statement to reflect the corrected take estimates.

National Environmental Policy Act

    In 2017, BOEM produced a final PEIS to evaluate the direct, 
indirect, and cumulative impacts of geological and geophysical survey 
activities in the GOM, pursuant to requirements of the National 
Environmental Policy Act. These activities include geophysical surveys, 
as are described in the MMPA petition submitted by BOEM to NMFS. The 
PEIS is available online at: https://www.boem.gov/Gulf-of-Mexico-Geological-and-Geophysical-Activities-Programmatic-EIS/. NOAA, through 
NMFS, participated in preparation of the PEIS as a cooperating agency 
due to its legal jurisdiction and special expertise in conservation and 
management of marine mammals, including its responsibility to authorize 
incidental take of marine mammals under the MMPA.
    In 2020, NMFS prepared a Record of Decision (ROD): (1) to adopt 
BOEM's Final PEIS to support NMFS' analysis associated with issuance of 
incidental take authorizations pursuant to section 101(a)(5)(A) or (D) 
of the MMPA and the regulations governing the taking and importing of 
marine mammals (50 CFR part 216); and (2) in accordance with 40 CFR 
1505.2, to announce and explain the basis for NMFS' decision to review 
and potentially issue incidental take authorizations under the MMPA on 
a case-by-case basis, if appropriate.
    The Council on Environmental Quality (CEQ) regulations state that 
agencies shall prepare supplements to either draft or final 
environmental impact statements if: (i) the agency makes substantial 
changes in the proposed action that are relevant to environmental 
concerns; or (ii) there are significant new circumstances or 
information relevant to environmental concerns and bearing on the 
proposed action or its impacts. (40 CFR 1502.09(c)). NMFS has 
considered CEQ's ``significance'' criteria at 40 CFR 1508.27 and the 
criteria relied upon for the 2020 ROD to determine whether any new 
circumstances or information are ``significant,'' thereby requiring 
supplementation of the 2017 PEIS.
    NMFS has not made any changes to the proposed action relevant to 
environmental concerns. For this rulemaking, NMFS reevaluated its 
findings related to the MMPA negligible impact standard and the LPAI 
standard governing its regulations in light of the corrected take 
estimates and other relevant new information. Based on that evaluation, 
NMFS reaffirms its negligible impact determinations and determined that 
the existing regulations prescribe the means of effecting the LPAI on 
the affected species or stocks and their habitat, and therefore made no 
changes to the regulations.
    NMFS also considered whether there are any significant new 
circumstances or information that are relevant to environmental 
concerns and have a bearing on this action or its impacts. Our 
rulemaking was conducted specifically to address errors in the take 
estimates that provided a basis for our 2021 final rule. We considered 
updated take estimates that corrected the errors and incorporated other 
new information, e.g., modeling of a more representative airgun array, 
updated marine mammal density information. We also consulted scientific 
publications from 2021-24, data that were collected by the agency and 
other entities after the PEIS was completed, field reports, and other 
sources (e.g., updated NMFS Stock Assessment Reports (SAR), reports 
produced under the BOEM-funded Gulf of Mexico Marine Assessment Program 
for Protected Species (GoMMAPPS) project (see https://www.boem.gov/gommapps)). The new circumstances and information are related to 
updated information on Rice's whales in the action area (population 
abundance, mortality and sources of mortality, distribution and 
occurrence) and any new data, analysis, or information on the effects 
of geophysical survey activity on marine mammals and relating to the 
effectiveness and practicability of measures to reduce the risk 
associated with impacts of such survey activity. Based on our review 
applying those criteria, NMFS has determined that supplementation of 
the 2017 PEIS is not warranted.

Letters of Authorization

    Under the incidental take regulations in effect for this specified 
activity, industry operators may apply for LOAs (50 CFR 217.186). We 
have made no changes to the regulations for obtaining an LOA. LOAs may 
be issued for any time period that does not exceed the effective period 
of the regulations, provided that NMFS is able to make the relevant 
determinations (50 CFR 217.183). Because the specified activity does 
not provide actual specifics of the timing, location, and survey design 
for activities that would be the subject of issued LOAs, such requests 
must include, at minimum, the information described at 50 CFR 
216.104(a)(1) and (2), and should include an affirmation of intent to 
adhere to the mitigation, monitoring, and reporting requirements 
described in the regulations. The level of effort proposed by an 
operator will be used to develop an LOA-specific take estimate based on 
the results of Weirathmueller et al. (2022). These results will be 
based on the appropriate source proxy (i.e., either 90-in\3\ single 
airgun or 4,130-, 5,110-, or 8,000-in\3\ airgun array).
    If applicants do not use the modeling provided by the rule, NMFS 
may publish a notice in the Federal Register soliciting public comment, 
if the model or inputs differ substantively from those that have been 
reviewed by NMFS and the public previously. Additional public review is 
not needed unless the model or inputs differ substantively from those 
that have been reviewed by NMFS and the public previously.
    Technologies continue to evolve to meet the technical, 
environmental, and economic challenges of oil and gas development. The 
use of technologies other than those described herein will be evaluated 
on a case-by-case basis and may require public review. Some seemingly 
new technologies proposed for use by operators are often extended 
applications of existing technologies and interface with the 
environment in essentially the same way as well-known or conventional 
technologies. NMFS

[[Page 31538]]

will evaluate such technologies accordingly and as described in the 
notice of issuance for the 2021 final rule. Please see that document 
for further detail.

Classification

Introduction

    Due to errors in the estimated take numbers provided by BOEM in 
support of its petition for the 2021 rule, the allowable amount of 
incidental take of marine mammals in the GOM is generally lower than 
the amount expected based on BOEM's projected activity levels. As a 
result, NMFS' ability to issue LOAs for take of marine mammals 
incidental to surveys related to oil and gas activities in the GOM has 
been limited, relative to what was intended under the rule for the 
specified activities. This rule corrects the estimated take numbers, 
allowing for the issuance of LOAs as intended under the 2021 rule. In 
addition, NMFS has incorporated newly available scientific data 
regarding marine mammal density in the GOM, and introduced new acoustic 
source configurations that provide more flexibility to applicants in 
terms of more accurately reflecting the anticipated effects of actual 
survey effort. The adjustments to allowable take under this final rule, 
relative to the 2021 final rule, have potential implications for oil 
and gas industry survey activity, associated oil and gas exploration 
and development, and marine mammals.

Surveys and Oil and Gas Exploration and Development

    If applicants cannot receive LOAs, either within the requested year 
or at all, due to the annual maximum or five-year maximum take 
allowable under the 2021 final rule for certain species, surveys may be 
delayed. To date, NMFS has issued approximately 70 LOAs, which is fewer 
than expected based on BOEM's projected levels of activity. Some of 
this discrepancy may be attributed to the aforementioned limitations on 
NMFS' ability to authorize take of certain species under the 2021 final 
rule and/or to generally increased regulatory uncertainty stemming from 
those limitations. In the absence of this rule, NMFS would anticipate 
continuing limitations on its ability to issue LOAs over the remaining 
period of effectiveness for the 2021 rule, though specific impacts 
would be dependent on demand and difficult to predict with precision. 
Delays could result in reductions in exploration and development 
activities in the GOM. This correction removes these unintended 
restrictions, averting the potential economic losses from delay.

Marine Mammals

    If NMFS is unable to issue some LOAs for the specified activities 
as a result of the erroneous take estimates analyzed for the 2021 rule, 
restrictions on incidental take may result in fewer incidences of 
harassment of marine mammals relative to those initially anticipated in 
2021. This final rule, which is based on corrected take estimates and 
other updated information for the same specified activities, may allow 
for more take of four species than would occur without this rule, 
though the updated take estimates (and thus allowable take) for all 
other species has decreased in reflection of updated density 
information. The corrections to allowable take may result in more 
actual take of some marine mammal species than has occurred under the 
rule to date, as a result of increased ability to issue requested LOAs. 
This final rule allows for the authorization of marine mammal take 
incidental to the same level of survey activities intended in the 2021 
rule and is issued in accordance with the same applicable negligible 
impact standard.
    To the extent that some number of surveys that would not have been 
able to move forward in compliance with the MMPA under the 2021 rule 
might now occur under this corrected rule, there may be effects on 
tourism, ecosystem services, and non-use valuations. NMFS describes 
each of these values below.

Tourism

    Marine mammal populations generate economic activity in the GOM 
and, more broadly, in the U.S. For example, the U.S. leads the world in 
whale watcher participation, with an estimated 4.9 million trips taken 
in 2008, or 38 percent of global whale watching trips. In 2013, the 
tourism and recreation sector of ocean-related activities in the GOM 
region (inclusive of all counties bordering the GOM) generated nearly 
$6.2 billion in wages and employed 310,000 individuals at 17,300 
establishments, for a total GDP contribution of approximately $13 
billion. Much of that ocean-related tourism is reliant on the diverse 
and abundant marine mammal and other marine wildlife populations.
    The presence of marine mammals generates regional income and 
employment opportunities most directly through businesses that conduct 
marine mammal watching tours and other marine wildlife-related 
operations, such as educational and environmental organizations. Whale 
watching activities alone support hundreds of jobs and tens of millions 
in regional income in the GOM. In addition, tourists drawn to the 
region to participate in these tours and activities spend money on 
goods and services in the regional economy, for example for meals, 
accommodations, or transportation to and from the whale watching 
destination. According to a 2009 report, the number of whale watchers 
in the GOM states increased to over 550,000 in 2008, nearly an order of 
magnitude increase over a ten year time period (Exhibit 5-1). Direct 
revenues from sales of whale watching tickets was $14.1 million that 
year, and the overall regional spending related to whale watching was 
nearly $45 million. An estimated 625 full-time equivalent jobs were 
directly involved in marine mammal recreation across all GOM states in 
2008.

[[Page 31539]]

[GRAPHIC] [TIFF OMITTED] TR24AP24.083

    Florida is the leading state for cetacean-based tourism in the 
country. Bottlenose dolphin viewing constitutes the majority of 
Florida's marine mammal-related tourism with average ticket prices of 
approximately $43 for boat-based trips and $95 for swim-with tours. 
Elsewhere in the GOM, in Alabama and Texas, average ticket prices are 
$11 to $22. Commercial whale watching activity is minimal in 
Mississippi and Louisiana.

Ecosystem Services

    Large whales provide ecosystem services, which are benefits that 
society receives from the environment. The services whales provide 
include contributing to sense of place, education, research, and they 
play an important role in the ecosystem. Large whales are considered 
ecosystem engineers, given their potential for trophic influence on 
their ecosystems. Their presence can reduce the risk of trophic 
cascades, which have previously affected smaller species when whale 
populations suffered historic declines. As large consumers, whales 
heavily impact food-web interactions and can promote primary 
productivity. Large whales may contribute to enhanced ocean 
productivity via a concept commonly known as the ``whale-pump.'' The 
``whale-pump'' refers to whales' contribution to vertical mixing, 
horizontal transfer, and the recycling of limiting nutrients in the 
ocean as they dive, migrate, and release fecal plumes and urine (Roman 
et al., 2014). Whales also play an important role in carbon cycling in 
the oceans. They accumulate carbon in their bodies over a lifetime and 
following death, can sequester tons of carbon in the deep sea (Pershing 
et al., 2010; Roman et al., 2014). Carbon stored in the deep sea 
reduces carbon in the atmosphere, which, in turn, can help fight 
against climate change. Chami et al. (2020) estimated that for the 
southern right whales, the average annual services value could be $2.2 
million.

Non-Use Benefits

    The protection and restoration of populations of endangered whales 
may also generate non-use benefits. Economic research has demonstrated 
that society places economic value on environmental assets, whether or 
not those assets are ever directly exploited. For example, society 
places real (and potentially measurable) economic value on simply 
knowing that large whale populations are flourishing in their natural 
environment (often referred to as ``existence value'') and will be 
preserved for the enjoyment of future generations. Using survey 
research methods, economists have developed several studies of non-use 
values associated with protection of whales or other marine mammals 
(table 15).
    In each study in table 15, researchers surveyed individuals on 
their willingness to pay (WTP) for programs that would maintain or 
increase marine mammal populations. One of the studies (Wallmo and Lew, 
2012) employed a stated preference method to estimate the value of 
recovering or down-listing eight ESA-listed marine species, including 
the North Atlantic right whale. Through a survey of 8,476 households, 
the authors estimated an average WTP (per household per year, for a 10-
year period) of $71.62 for recovery of the species which, if 
extrapolated nationwide, suggests Americans are willing to pay 
approximately $4.38 billion for right whale recovery. While the other 
studies noted do not focus specifically on the North Atlantic right 
whale, they do demonstrate that individuals derive significant economic 
value from the protection of marine mammals. As noted, the value of 
whales might not be adequately captured by non-use values of this kind. 
Death or suffering of whales might be believed to be intrinsically bad, 
because it is a welfare loss in itself.
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BILLING CODE 3510-22-C

Regulatory Flexibility Act

    Pursuant to section 605(b) of the Regulatory Flexibility Act, the 
Chief Counsel for Regulation of the Department of Commerce certified to 
the Chief Counsel for Advocacy of the Small Business Administration at 
the proposed rule stage that this rule would not have a significant 
economic impact on a substantial number of small entities. This rule 
makes no changes to the existing regulations. Upon receiving updated 
information following the discovery that the estimates of incidental 
take of marine mammals anticipated from the activities analyzed for the 
January 19, 2021, final rule were erroneous, NMFS undertook this action 
to analyze the updated information and underlying take estimates and 
decide whether revisions to the January 19, 2021, final rule were 
warranted. NMFS has found that revisions to the regulations are not 
warranted. There are no changes to the specified activities, the 
specified geographical region in

[[Page 31541]]

which those activities would be conducted, the original 5-year period 
of effectiveness, or to the current mitigation and monitoring 
requirements implemented by the January 19, 2021, final rule. Because 
there have been no changes to the existing regulations, there are no 
economic impacts on small entities. A regulatory flexibility analysis 
therefore is not required, and none has been prepared. No comments were 
received that would change this determination.
    Note that NMFS prepared a final regulatory flexibility analysis 
(FRFA), as required by Section 603 of the Regulatory Flexibility Act, 
for the regulations issued under the January 19, 2021, final rule. That 
FRFA described the economic effects on small entities. A copy of the 
FRFA is available as Appendix B to the RIA that accompanied the January 
19, 2021, final rule. No changes have been made to the 2021 regulations 
that would affect the findings of that FRFA, which were summarized in 
the notice of issuance for the 2021 final rule (86 FR 5443, January 19, 
2021).
    This rule does not contain a change to a collection of information 
requirement for purposes of the Paperwork Reduction Act of 1995. The 
existing collection of information requirements continue to apply under 
the following OMB Control Number(s): 0648-0151.
    Notwithstanding any other provision of the law, no person is 
required to respond to, nor shall any person be subject to a penalty 
for failure to comply with, a collection of information subject to the 
requirements of the PRA, unless that collection of information displays 
a currently valid OMB Control Number.

List of Subjects in 50 CFR Part 217

    Exports, Fish, Imports, Indians, Labeling, Marine mammals, 
Penalties, Reporting and recordkeeping requirements, Seafood, 
Transportation.

    Dated: April 12, 2024.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.

    As described above, because NMFS does not find that new mitigation 
measures are required, this rule does not amend the current applicable 
regulations at 50 CFR part 217 Subpart S (Sec. Sec.  217.180 through 
217.189). Thus, no amendatory instructions are necessary.

[FR Doc. 2024-08257 Filed 4-23-24; 8:45 am]
BILLING CODE 3510-22-P