Proposed Rule2022-28208
Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Geophysical Surveys in the Gulf of Mexico
Primary source
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Published
January 5, 2023
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS is reassessing the statutorily mandated findings supporting its January 19, 2021, final rule and Regulations Governing Taking Marine Mammals Incidental to Geophysical Survey Activities in the Gulf of Mexico issued pursuant to the Marine Mammal Protection Act (MMPA), in light of updated information following the discovery that the estimates of incidental take of marine mammals anticipated from the activities analyzed for the 2021 regulations were erroneous. The correction of this error, as well as other newly available and pertinent information, has bearing on the analyses supporting some of the prior 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. Here, in light of the new information, NMFS presents new "negligible impact" analyses supporting our preliminary affirmance of the negligible impact determinations for all species, and proposes to affirm that the existing regulations, which contain mitigation, monitoring, and reporting requirements, are consistent with the "least practicable adverse impact standard" of the MMPA. Pursuant to the MMPA, NMFS is requesting comments on its revised negligible impact analyses and proposed findings and proposed retention of the existing regulations as consistent with the MMPA's least practicable adverse impact standard and will consider public comments relevant to this proposed rule prior to issuing any final rule. Agency responses will be included in the notice of the final decision.
Full Text
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[Federal Register Volume 88, Number 3 (Thursday, January 5, 2023)]
[Proposed Rules]
[Pages 916-948]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-28208]
[[Page 915]]
Vol. 88
Thursday,
No. 3
January 5, 2023
Part II
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; Proposed Rule
Federal Register / Vol. 88 , No. 3 / Thursday, January 5, 2023 /
Proposed Rules
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 217
[Docket No. 221221-0280]
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: Proposed rule; request for comments.
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SUMMARY: NMFS is reassessing the statutorily mandated findings
supporting its January 19, 2021, final rule and Regulations Governing
Taking Marine Mammals Incidental to Geophysical Survey Activities in
the Gulf of Mexico issued pursuant to the Marine Mammal Protection Act
(MMPA), in light of updated information following the discovery that
the estimates of incidental take of marine mammals anticipated from the
activities analyzed for the 2021 regulations were erroneous. The
correction of this error, as well as other newly available and
pertinent information, has bearing on the analyses supporting some of
the prior 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. Here, in
light of the new information, NMFS presents new ``negligible impact''
analyses supporting our preliminary affirmance of the negligible impact
determinations for all species, and proposes to affirm that the
existing regulations, which contain mitigation, monitoring, and
reporting requirements, are consistent with the ``least practicable
adverse impact standard'' of the MMPA. Pursuant to the MMPA, NMFS is
requesting comments on its revised negligible impact analyses and
proposed findings and proposed retention of the existing regulations as
consistent with the MMPA's least practicable adverse impact standard
and will consider public comments relevant to this proposed rule prior
to issuing any final rule. Agency responses will be included in the
notice of the final decision.
DATES: Comments and information must be received no later than February
6, 2023.
ADDRESSES: Submit all electronic public comments via the Federal e-
Rulemaking Portal. Go to <a href="http://www.regulations.gov">www.regulations.gov</a> and enter NOAA-NMFS-2022-
0090 in the Search box. Click on the ``Comment'' icon, complete the
required fields, and enter or attach your comments.
Instructions: Comments sent by any other method, to any other
address or individual, or received after the end of the comment period,
may not be considered by NMFS. All comments received are a part of the
public record and will generally be posted for public viewing on
<a href="http://www.regulations.gov">www.regulations.gov</a> without change. All personal identifying
information (e.g., name, address), confidential business information,
or otherwise sensitive information submitted voluntarily by the sender
will be publicly accessible. NMFS will accept anonymous comments (enter
``N/A'' in the required fields if you wish to remain anonymous).
Attachments to electronic comments will be accepted in Microsoft Word,
Excel, or Adobe PDF file formats only.
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
(LOAs) 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 discovered in the maximum annual and 5-year take numbers
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 rule has been limited. NMFS has produced corrected take
estimates, including updates to the best available science incorporated
to the take estimation process (i.e., new marine mammal density
information), with the result that allowable take numbers are changed
through this rule. Changes to the take numbers require additional
analysis to ensure that the necessary statutory findings can still be
made. This proposed 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 errors in
the take estimates that were considered for the final rule. NMFS
solicits public comment on this 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.
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 ``least
practicable adverse impact'' on the affected species or stocks and
their habitat (see the discussion below in the Proposed 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
regulations regarding geophysical survey activities, which NMFS
proposes to reaffirm. The regulations contain requirements for
mitigation, monitoring, and reporting, including:
<bullet> Standard detection-based mitigation measures, including
use of visual and acoustic observation to detect marine mammals and
shut down acoustic sources in certain circumstances;
[[Page 917]]
<bullet> A time-area restriction designed to avoid effects to
bottlenose dolphins in times and places believed to be of particular
importance;
<bullet> Vessel strike avoidance measures; and
<bullet> Monitoring and reporting requirements.
The ITR would continue 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 least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
taking for certain subsistence uses (referred to as ``mitigation'');
and set forth requirements pertaining to the monitoring and reporting
of the takings. The definitions of all applicable MMPA statutory terms
cited above are included in the relevant sections below.
On October 17, 2016, BOEM submitted a revised petition \1\ to NMFS
for rulemaking under section 101(a)(5)(A) of the MMPA to authorize take
of marine mammals incidental to conducting geophysical surveys during
oil and gas industry exploration and development activities in the GOM.
This revised petition was deemed adequate and complete based on NMFS'
implementing regulations at 50 CFR 216.104.
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\1\ In the 2018 notice of proposed rulemaking (83 FR 29212, June
22, 2018), NMFS provided a brief history of prior petitions received
from BOEM's predecessor agencies.
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NMFS published a notice of proposed rulemaking in the Federal
Register for a 60-day public review on June 22, 2018 (83 FR 29212)
(``2018 proposed rule''). All comments received are available online at
<a href="http://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>.
On February 24, 2020, BOEM submitted a notice to NMFS of its
``updated proposed action and action area for the ongoing [ITR]
process[.]'' This update consisted of removal of the area then under a
Congressional leasing moratorium under the Gulf of Mexico Energy
Security Act (GOMESA) (Sec. 104, Pub. L. 109-432) \2\ from
consideration in the ITR. BOEM stated in its notice that survey
activities are not likely to be proposed within the area subject to the
leasing moratorium during the 5-year period of effectiveness for the
ITR and, therefore, that the ``number, type, and effects of any such
proposed [survey] activities are simply too speculative and uncertain
for BOEM to predict or meaningfully analyze.'' Based on this updated
scope, BOEM on March 26, 2020, submitted revised projections of
expected activity levels and corresponding changes to modeled acoustic
exposure numbers (i.e., take estimates). BOEM's notice and updated
information are available online at: <a href="http://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>. NMFS incorporated this change in scope 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), 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 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 was 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. 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, to revise its incidental take rule
accordingly.
Since issuance of the 2021 final rule (at time this proposed rule
was submitted to the Federal Register), NMFS has issued 34 LOAs
(<a href="http://www.fisheries.noaa.gov/issued-letters-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">www.fisheries.noaa.gov/issued-letters-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>). Of these 34 LOAs, 17
have included authorization of take for killer whales. An additional 7
requests for authorization remain pending as a result of limitations on
NMFS' ability to authorize additional take of killer whales under the
rule.
National Environmental Policy Act (NEPA)
In 2017, BOEM produced a final Programmatic Environmental Impact
Statement (PEIS) to evaluate the direct, indirect, and cumulative
impacts of geological and geophysical survey activities in the GOM,
pursuant to requirements of NEPA. These activities include geophysical
surveys, as are described in the MMPA petition submitted by BOEM to
NMFS. The PEIS is available online at: <a href="http://www.boem.gov/Gulf-of-Mexico-Geological-and-Geophysical-Activities-Programmatic-EIS/">www.boem.gov/Gulf-of-Mexico-Geological-and-Geophysical-Activities-Programmatic-EIS/</a>. 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.
[[Page 918]]
In 2020, NMFS prepared a Record of Decision (ROD) for the following
purposes: (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
``[a]gencies 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)). In addition,
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.
For this proposed action, NMFS has reevaluated its findings related
to the MMPA negligible impact standard and the least practicable
adverse impact standard governing its regulations in light of the
corrected take estimates and other relevant new information. Based on
that evaluation, NMFS preliminarily reaffirms its negligible impact
determinations and preliminarily finds that the corrected and
additional data do not result in the need for revised mitigation and
monitoring measures under the least practicable adverse impact
standard.
NMFS also considered whether there are any significant new
circumstances or information that are relevant to environmental
concerns and have a bearing on this proposed action or its impacts. For
our consideration of new circumstances and information, we consulted
scientific publications from 2021-22, 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 <a href="http://www.boem.gov/gommapps">www.boem.gov/gommapps</a>)). 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 this review,
NMFS has preliminarily determined that supplementation of the 2017 PEIS
is not warranted.
Summary of the Proposed Action
This proposed rule provides analysis of the same activities and
activity levels considered for the 2021 final rule for the same
original five-year period of time and utilizes 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.
This proposed rule also incorporates expanded modeling results that
estimate take utilizing the existing methodology but also consider the
effects of using smaller (relative to the proxy source originally
defined by BOEM) airgun arrays currently prevalent, as evidenced by LOA
applications received by NMFS to date (see <a href="http://www.fisheries.noaa.gov/issued-letters-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">www.fisheries.noaa.gov/issued-letters-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>).
There are no changes to the nature or level of the specified
activities within or across years or to the geographic scope of the
activity. Based on our preliminary assessment of the specified activity
in light of the revised take estimates and other new information, we
have determined that the 2021 regulations at 50 CFR 217.180, including
the required mitigation and associated monitoring measures, satisfy the
MMPA requirement to prescribe the means of effecting the least
practicable adverse impact on the affected species or stocks and their
habitat, and therefore, do not propose to change those regulations, nor
do we propose to change the requirements pertaining to monitoring and
reporting. This rulemaking supplements the information supporting the
2021 incidental take rule. This proposed rule would not change the
existing expiration date of the 2021 regulations (April 19, 2026). 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) would remain
unchanged under this proposed 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 four species: Rice'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 the 2021 analyses for all species, as elements of the
framework are dependent on information related to stock abundance,
which has been updated. 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 included in the documents provided
and produced in support of 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 propose to change the interpretation and
implementation as laid out in the 2021 final rule.
Description of the Specified Activity
Overview
The specified activity for this proposed 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 limiting the projections to 5
years and removing activity assumed to occur within the areas removed
from the
[[Page 919]]
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 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. Please see 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).
Generally speaking, survey activity projected by BOEM may occur
within Federal territorial waters and waters of the U.S. Exclusive
Economic Zone (EEZ) (i.e., to 200 nautical miles (nmi)) within the GOM,
and/or corresponding with BOEM's GOM Outer Continental Shelf planning
areas (i.e., Western Planning Area (WPA), Central Planning Area (CPA),
Eastern Planning Area (EPA)).
Dates and Duration
The dates and duration of the specified activities considered for
this proposed 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 proposed action is
unchanged from the one considered for the 2021 final rule. The OCS
planning areas are depicted in Figure 1, and the overlap of the former
GOMESA moratorium area, which is now withdrawn from leasing
consideration, with the geographical region (as well as with the
modeling zones) 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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[GRAPHIC] [TIFF OMITTED] TP05JA23.000
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[GRAPHIC] [TIFF OMITTED] TP05JA23.001
BILLING CODE 3510-22-C
Summary of Representative Sound Sources
The 2021 final rule allows for the authorization of take, through
LOAs, incidental to airguns of different sizes and configurations. The
supporting modeling considered two specific airgun array sizes/
configurations (as well as a single airgun). For this proposed rule,
modeling of a third representative airgun size is also specifically
considered. 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. Modeling
of a smaller, more representative, airgun array considered in this
proposed rule is described in a 2022 memorandum (Weirathmueller et al.,
2022). These reports provide full detail regarding the modeled acoustic
sources and survey types and are available online at:
<a href="http://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>.
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 conservative proxy for surveys using a boomer or sparker). The
nominal airgun sources used for analysis of the specified activity
include a single airgun (90-in\3\ airgun) and a large airgun array
(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 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
worst-case modeling results (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, NMFS will evaluate any
such developments on a case-specific basis to determine whether
[[Page 921]]
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.
Table 1--Projected Levels of Effort in 24-Hr Survey Days for Five Years, by Zone and Survey Type \1\
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Shallow Total
Year Zone \2\ 2D \3\ 3D NAZ \3\ 3D WAZ \3\ Coil \3\ VSP \3\ Total hazards Boomer \4\ HRG \4\ (shallow)
(deep) \3\ \4\ \4\
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1........................................................... 1 0 0 0 0 0 0 0 0 0 0
2 0 236 0 0 0 236 2 0 18 20
3 0 30 0 0 0 30 0 0 4 4
4 0 0 0 0 0 0 0 0 0 0
5 54 373 184 79 2 692 0 0 25 25
6 0 186 49 21 0 256 0 0 10 10
7 46 346 166 71 1 630 0 0 23 23
-----------------------------------------------------------------------------------------------------------------------------------
Total................................................... .......... 100 1,171 399 171 3 1,844 2 0 80 82
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2........................................................... 1 0 0 0 0 0 0 0 0 0 0
2 0 354 42 19 0 415 2 0 18 20
3 0 0 0 0 0 0 0 0 4 4
4 6 0 0 0 0 6 0 0 0 0
5 0 373 184 79 2 638 0 0 25 25
6 0 99 0 0 0 99 0 0 11 11
7 20 336 162 69 1 588 0 0 23 23
-----------------------------------------------------------------------------------------------------------------------------------
Total................................................... .......... 26 1,162 388 167 3 1,746 2 0 81 83
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
3........................................................... 1 0 0 0 0 0 0 0 0 0 0
2 0 236 0 0 0 236 2 0 18 20
3 0 0 0 0 0 0 0 0 4 4
4 0 0 0 0 0 0 0 0 0 0
5 0 328 154 66 2 550 0 0 26 26
6 0 186 49 21 0 256 0 0 12 12
7 0 306 139 60 1 506 0 0 24 24
-----------------------------------------------------------------------------------------------------------------------------------
Total................................................... .......... 0 1,056 342 147 3 1,548 2 0 84 86
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
4........................................................... 1 0 0 0 0 0 0 0 0 0 0
2 0 354 42 19 0 415 2 1 16 19
3 0 30 0 0 0 30 0 0 3 3
4 12 11 0 0 0 23 0 0 0 0
5 27 237 92 40 2 398 0 0 26 26
6 0 99 0 0 0 99 0 0 12 12
7 63 255 94 40 1 453 0 0 24 24
-----------------------------------------------------------------------------------------------------------------------------------
Total................................................... .......... 102 986 228 99 3 1,418 2 1 81 84
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
5........................................................... 1 0 0 0 0 0 0 0 0 0 0
2 0 236 0 0 0 236 0 0 19 19
3 0 0 0 0 0 0 0 0 3 3
4 0 17 0 0 0 17 0 0 0 0
5 0 283 184 79 2 548 2 1 24 27
6 0 99 0 0 0 99 0 0 13 13
7 0 313 162 69 2 546 2 1 23 26
-----------------------------------------------------------------------------------------------------------------------------------
Total................................................... .......... 0 948 346 148 4 1,446 4 2 82 88
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Projected levels of effort in 24-hr survey days. 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 concurrently made available to the public via BOEM's 2020 notice to NMFS of its updated
scope.
\2\ Zones follow the zones depicted in Figure 2.
\3\ Deep penetration survey types include 2D, which uses one source vessel with one source array; 3D NAZ, which uses two source vessels using one source array each; 3D WAZ and coil, each of
which uses four source vessels using one source array each (but with differing survey design); and VSP, which uses one source vessel with one source array. ``Deep'' refers to survey type,
not to water depth. Assumptions related to modeled source and survey types were made by BOEM in its petition for rulemaking.
\4\ Shallow penetration/HRG survey types include shallow hazards surveys, assumed to use a single 90-in\3\ airgun or boomer, and high-resolution surveys using the multibeam echosounder, side-
scan sonar, and CHIRP sub-bottom profiler systems concurrently. ``Shallow'' refers to survey type, not to water depth.
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 recent addenda) and PEIS, for additional detail
regarding these activities and the region. Required mitigation,
monitoring, and reporting measures are described later in this document
(see Proposed Mitigation and Proposed Monitoring and Reporting).
[[Page 922]]
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' SARs). 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 either the 2018 notice of proposed
rulemaking or 2021 notice of issuance of the 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 rule, we consider beaked whales
and Kogia spp. as guilds. In this proposed 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., 2022). The updated density models retain the treatment of
beaked whales and Kogia spp. as guilds and have additionally
consolidated four 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. Therefore,
reference to ``blackfish'' hereafter includes the melon-headed whale,
false killer whale, pygmy killer whale, and killer whale.\3\ NMFS
requests comment regarding whether there is additional data that it
should consider in this rulemaking related to the aforementioned
species, in light of NMFS' preliminary determination that Garrison et
al. (2022) reflects the best available scientific information.
---------------------------------------------------------------------------
\3\ NMFS' 2021 final rule provided take estimates separately for
the melon-headed whale, false killer whale, pygmy killer whale, and
killer whale. This proposed 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.,
2022). 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. (2022) models are based on
survey data from 2003-2018. 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 notice of proposed
rulemaking. 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' 2021 SARs (the most recent SARs
available at the time of publication) (Hayes et al., 2022).
Table 2--Marine Mammals Potentially Present in the Specified Geographical Region
--------------------------------------------------------------------------------------------------------------------------------------------------------
NMFS stock
ESA/MMPA abundance (CV, Predicted mean (CV)/ Annual
Common name Scientific name Stock status; Nmin, most recent maximum abundance PBR M/SI
strategic (Y/ abundance survey) \3\ \4\
N) \1\ \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae
(rorquals):
Rice's whale \5\............. Balaenoptera ricei.. Gulf of Mexico..... E/D; Y 51 (0.50; 34; 2017- 37 (0.52).......... 0.1 0.5
18).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
Sperm whale.................. Physeter GOM................ E/D; Y 1,180 (0.22; 983; 3,007 (0.15)....... 2.0 9.6
macrocephalus. 2017-18).
Family Kogiidae:
Pygmy sperm whale............ Kogia breviceps..... GOM................ -; N 336 (0.35; 253; 980 (0.16)......... 2.5 31
2017-18) \6\ \7\.
Dwarf sperm whale............ K. sima............. GOM................ -; N
Family Ziphiidae (beaked whales):
Cuvier's beaked whale........ Ziphius cavirostris. GOM................ -; N See Footnotes 7-8.. 803 (0.18)......... 0.1 5.2
Gervais beaked whale......... Mesoplodon europaeus GOM................ -; N
[[Page 923]]
Blainville's beaked whale.... M. densirostris..... GOM................ -; N 0.7
Family Delphinidae:
Rough-toothed dolphin........ Steno bredanensis... GOM................ -; N 3,509 (0.67; Unk.; 4,853 (0.19)....... Undet. 39
2009).
Common bottlenose dolphin \7\ Tursiops truncatus GOM Oceanic........ -; N 7,462 (0.31; 5,769; 155,453 (0.13) 58 32
truncatus. 2017-18). (Shelf) 9,672
(0.15) (Oceanic).
GOM Continental -; N 63,280 (0.11; 556 65
Shelf. 57,917; 2017-18).
GOM Coastal, -; N 11,543 (0.19; 89 28
Northern. 9,881; 2017-18).
GOM Coastal, -; N 20,759 (0.13; 167 36
Western. 18,585; 2017-18).
Clymene dolphin.............. Stenella clymene.... GOM................ -; N 513 (1.03; 250; 4,619 (0.35)....... 2.5 8.4
2017-18).
Atlantic spotted dolphin..... S. frontalis........ GOM................ -; N 21,506 (0.26; 6,187 (0.33) 166 36
17,339; 2017-18). (Shelf) 1,782
(0.19) (Oceanic).
Pantropical spotted dolphin.. S. attenuata GOM................ -; N 37,195 (0.24; 67,225 (0.27)...... 304 241
attenuata. 30,377; 2017-18).
Spinner dolphin.............. S. longirostris GOM................ -; N 2,991 (0.54; 1,954; 5,548 (0.40)....... 20 113
longirostris. 2017-18).
Striped dolphin.............. S. coeruleoalba..... GOM................ -; N 1,817 (0.56; 1,172; 5,634 (0.18)....... 12 13
2017-18).
Fraser's dolphin............. Lagenodelphis hosei. GOM................ -; N 213 (1.03; 104; 1,665 (0.73)....... 1 Unk.
2017-18).
Risso's dolphin.............. Grampus griseus..... GOM................ -; N 1,974 (0.46; 1,368; 1,501 (0.27)....... 14 5.3
2017-18).
Melon-headed whale........... Peponocephala GOM................ -; N 1,749 (0.68; 1,039; 6,113 (0.20)....... 10 9.5
electra. 2017-18).
Pygmy killer whale........... Feresa attenuata.... GOM................ -; N 613 (1.15; 283; 2.8 1.6
2017-18).
False killer whale........... Pseudorca crassidens GOM................ -; N 494 (0.79; 276; 2.8 2.2
2017-18).
Killer whale................. Orcinus orca........ GOM................ -; N 267 (0.75; 152; 1.5 Unk.
2017-18).
Short-finned pilot whale..... Globicephala GOM................ -; N 1,321 (0.43; 934; 2,741 (0.18)....... 7.5 3.9
macrorhynchus. 2017-18).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ ESA status: Endangered (E)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted
under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be
declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated
under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>. CV
is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\3\ This information represents species- or guild-specific abundance predicted by habitat-based cetacean density models (Roberts et al., 2016; Garrison
et al., 2022). These models provide the best available scientific information regarding predicted density patterns of cetaceans in the U.S. Gulf of
Mexico, and we provide the corresponding abundance predictions as a point of reference. Total abundance estimates were produced by computing the mean
density of all pixels in the modeled area and multiplying by its area. Abundance predictions for Fraser's dolphin and rough-toothed dolphin from
Roberts et al. (2016); abundance predictions for other taxa represent the maximum predicted abundance from Garrison et al. (2022).
\4\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial
fisheries, ship strike). These values are generally considered minimums because, among other reasons, not all fisheries that could interact with a
particular stock are observed and/or observer coverage is very low, and, for some stocks (such as the Atlantic spotted dolphin and continental shelf
stock of bottlenose dolphin), no estimate for injury due to the Deepwater Horizon oil spill has been included. See SARs for further discussion.
\5\ The 2021 final rule refers to the GOM Bryde's whale (Balaenoptera edeni). These whales were subsequently described as a new species, Rice's whale
(Balaenoptera ricei) (Rosel et al., 2021).
\6\ NMFS' 2020 SARs state that the abundance estimate provided for Kogia spp. is likely a severe underestimate because it was not corrected for the
probability of detection on the trackline, and because Kogia spp. are often difficult to see, present little of themselves at the surface, do not
fluke when they dive, and have long dive times. In addition, they exhibit avoidance behavior towards ships and changes in behavior towards approaching
survey aircraft. See Hayes et al. (2021).
\7\ Abundance estimates are in some cases reported for a guild or group of species when those species are difficult to differentiate at sea. Similarly,
habitat-based cetacean density models are based in part on available observational data which, in some cases, is limited to genus or guild in terms of
taxonomic definition. NMFS' SARs present pooled abundance estimates for Kogia spp. and Mesoplodon spp., while Garrison et al. (2022) produced density
models to genus level for Kogia spp. and as a guild for beaked whales (Ziphius cavirostris and Mesoplodon spp.) and ``blackfish'' (pygmy killer whale,
false killer whale, melon-headed whale, and killer whale). Finally, Garrison et al. (2022) produced density models for bottlenose dolphins that do not
differentiate between stocks, but between oceanic and shelf dolphins.
\8\ NMFS' 2020 SARs provide various abundance estimates for beaked whales: Cuvier's beaked whale, 18 (CV = 0.75); Gervais' beaked whale, 20 (CV=0.98);
unidentified Mesoplodont species, 98 (CV = 0.46); and unidentified Ziphiids, 181 (CV = 0.31). The SARs state that these estimates likely represent
severe underestimates, as they were not corrected for the probability of detection on the trackline, and due to the long dive times of these species.
See Hayes et al. (2021).
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,
[[Page 924]]
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 these purposes, represent the best available
information. Specifically, for 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 most appropriate because
they were used to generate the exposure estimates and therefore,
provide the most relevant comparison.
As discussed in footnote 3 of Table 2, NMFS' 2021 final rule
provided take estimates separately for the melon-headed whale, false
killer whale, pygmy killer whale, and killer whale. This proposed 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.
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 2003-2018),
and the updated models notably include post-Deepwater Horizon (DWH) oil
spill survey data and, for the first time, winter survey data.
Nonetheless, interested members of the public may review the 2018
proposed rule and supporting documentation, which assumed slightly
greater activity levels and larger take numbers, and still found a
negligible impact on all four blackfish species.
NMFS does not have sufficient information to support apportioning
those blackfish takes to species, but we note that the sum of annual
average evaluated take for the four 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. While some may speculate
that estimated take of killer whales (as part of the blackfish group)
has increased relative to that evaluated in the 2021 final rule (annual
average take of 52), NMFS has no specific information to support such
an assumption.
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 serious
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 proposed 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 evaluation of the environmental baseline, which is
considered as part of the negligible impact analysis, we consider any
known areas of importance as marine mammal habitat (e.g., recognized
Biologically Important Areas (BIA)). We also consider other relevant
events, such as unusual mortality events (UME) and the 2010 DWH oil
spill. The 2018 notice of proposed rulemaking provided detailed
discussion of important marine mammal habitat, relevant UMEs, and of
the DWH oil spill. The 2021 notice of issuance of the final rule
updated those discussions as necessary. That information is
incorporated by reference here and updated where necessary. 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 that impacts our consideration of that event as part of
the environmental baseline. We do note that 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).
Areas of important marine mammal habitat may include designated
critical habitat for ESA-listed species (as defined by section 3 of the
ESA) or other known areas not formally designated pursuant to any
statute or other law. Important areas may include areas of known
importance for reproduction, feeding, or migration, or areas where
small and resident populations are known to occur.
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. However, a
Rice's whale BIA is recognized (LaBrecque et al., 2015). This year-
round BIA was discussed in the aforementioned notices, and we do not
repeat the description of the 2015 BIA.
NOAA conducted a status review of the former GOM Bryde's whale
(Rosel et al., 2016). The review expanded the BIA description by
stating that, due to the depth of some sightings, the area is more
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. Following the
description provided by Rosel et al. (2016), the 2018 proposed
rulemaking considered a Rice's whale ``core habitat area'' that was
designated as 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 subsequently developed an updated description of a ``core
distribution area''
[[Page 925]]
(<a href="http://www.fisheries.noaa.gov/resource/map/rices-whale-core-distribution-area-map-gis-data">www.fisheries.noaa.gov/resource/map/rices-whale-core-distribution-area-map-gis-data</a>), which we refer to herein (Figure 3) while retaining
the previous terminology for continuity with the 2021 rule (``core
habitat area''). The updated description is based on visual sightings
and tag data, and does not imply knowledge of habitat preferences. The
map was created by first drawing a convex hull polygon around all
recorded Rice's whale sighting locations (including those recorded as
Bryde's whale, Bryde's/sei, and Bryde's/sei/fin) from NMFS surveys in
the northeast GOM, telemetry tag locations from a single whale tagged
in 2010 (Soldevilla et al., 2017), and acousonde tag locations for one
whale tagged in 2015 (Soldevilla et al., 2017), comprising a total of
212 data points collected between 1989 and 2018. It should be noted
that, other than the positions obtained from the two individually
tagged whales, it is unknown how many individual whales these sightings
represent as individuals may have been sighted more than once during a
cruise or across years. The polygon was trimmed on the western side to
the 410 m isobath, based on the deepest known sighting (408 m).
In context of the sparse data from which to accurately define the
distribution and because many of the sightings fall on the boundary of
the convex hull polygon, a buffer was added to avoid underestimating
the potential range of the species. A 10-km buffer was applied to the
polygon to capture the uncertainty in position and the strip width of
the visual surveys. This buffer ensures that no sightings are on a
boundary of the area. An additional 20-km buffer was added to account
for the possible movement whales could make in any one direction from
an observed sighting. This buffer was identified by examining the daily
movement data from a whale tagged for 33 days in 2010 with a satellite-
linked telemetry tag. Two alternative methods were used to identify the
best indicator of possible daily distance traveled by a whale. First, a
``daily range'' of movement was estimated by calculating swim speeds
(km/hr) based upon the distances (and times) between successive
satellite-tag returns and multiplying that by 24 hr. These daily ranges
were highly skewed, with most in the 10-30 km range when the whale
remained in a relatively small area and a few large ranges when the
whale was traveling northeast to southeast through the habitat. The
mean of this daily range was 46 km and the median was 21 km. To reduce
the influence of differences in the number of satellite positions
returned on any given day, the total distance moved within each 24-hr
period was summed using all satellite positions in that day. The median
of this daily range was 17 km and the mean was 30 km. As the median is
a better measure of central tendency than the mean of highly skewed
distributions such as those seen here, 20 km was chosen as the most
likely distance a given observed whale could move within a day of the
detection. In combination with the 10-km buffer to account for
uncertainty in whale location during the sighting, this results in the
placement of a total of a 30-km buffer around the convex hull polygon
based on sighting locations, producing the area depicted in Figure 3
(see Proposed Mitigation).
Potential Effects of the Specified Activities on Marine Mammals and
Their Habitat
In NMFS' 2018 notice of proposed rulemaking (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 notice of issuance for the 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 rule was issued.
Having considered this information, we have determined that there is no
new information that substantively affects our analysis of potential
impacts on marine mammals and their habitat that appeared in the 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 notice of
proposed rulemaking and 2021 notice of issuance of the 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 Proposed 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' preliminary 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
value 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.
[[Page 926]]
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 notice, and associated companion documents available online, 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 this ITR;
that discussion is not repeated as no changes have been made to the
relevant acoustic criteria. See Tables 3 and 4.
Table 3--Behavioral Exposure Criteria
----------------------------------------------------------------------------------------------------------------
Probability of response to frequency-weighted rms SPL
Group ---------------------------------------------------------------
120 (%) 140 (%) 160 (%) 180 (%)
----------------------------------------------------------------------------------------------------------------
Beaked whales................................... 50 90 n/a n/a
All other species............................... n/a 10 50 90
----------------------------------------------------------------------------------------------------------------
Table 4--Exposure Criteria for Auditory Injury
----------------------------------------------------------------------------------------------------------------
Cumulative sound exposure
level \2\
Hearing group Peak pressure -------------------------------
\1\ (dB) Impulsive Non-impulsive
(dB) (dB)
----------------------------------------------------------------------------------------------------------------
Low-frequency cetaceans......................................... 219 183 199
Mid-frequency cetaceans......................................... 230 185 198
High-frequency cetaceans........................................ 202 155 173
----------------------------------------------------------------------------------------------------------------
\1\ Referenced to 1 [mu]Pa; unweighted within generalized hearing range.
\2\ Referenced to 1 [mu]Pa\2\-s; weighted according to appropriate auditory weighting function. Airguns and the
boomer are treated as impulsive sources; other HRG sources are treated as non-impulsive.
Acoustic Exposure Modeling
Zeddies et al. (2015, 2017a) provided estimates of the annual
marine mammal acoustic exposure caused by sounds from geophysical
survey activity in the GOM for 10 years of notional activity levels, 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 notice of proposed rulemaking (83 FR 29212, June 22,
2018), and through 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, the interested reader should see the
reports (available online at: <a href="http://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>) and review discussion provided in prior Federal Register
notices.
All acoustic exposure modeling, including source and propagation
modeling, was redone in support of the action described herein for the
reasons described below. 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., 2022)
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.,
[[Page 927]]
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 six 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.,
2022). 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. 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., 2022).
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' 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.,
[[Page 928]]
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, 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 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-hr exposure estimates, specific to each species, zone, survey type,
and season. These 24-hr 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 total levels of activity
projected to occur across a number of years.)
NMFS contacted BOEM regarding the issue in June 2021. Following an
initial discussion, BOEM determined that when it reduced its scope of
specified activity by removing the GOMESA moratorium area from the
proposed action, it underestimated the level of take by inadvertently
factoring species density estimates into its revised exposure estimates
twice. Generally, this miscalculation caused BOEM to underestimate the
total predicted exposures of species from all survey activities in its
revision to the incidental take rule application, most pronouncedly for
those species with the lowest densities. The practical effect of this
miscalculation is that the full amount of activity for which BOEM
sought incidental take coverage in its application cannot be authorized
under the existing incidental take rule.
In September 2021, BOEM provided corrected exposure estimates.
These are available in BOEM's September 2021 ``Corrected Exposure
Estimates'' letter, available online at: <a href="http://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>. 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,
including the following explanation.
When calculating estimated takes for the 2020 revision to the scope
of activity, BOEM multiplied the modeled number of animals above
threshold per day of survey (Nz,s,t),\4\ for each type of survey in
each zone, by the habitat-based density of the species in each zone
(rz,t) \5\ and the number of days of effort for each survey and zone by
year (LoEz,s,y) \6\. However, the species' habitat-based density had
already been included in the modeled number of animals above threshold
(Nz,s,t). The species' habitat-based density had therefore been
factored in twice.
---------------------------------------------------------------------------
\4\ Nz,s,t is the number of individuals of a species, t,
expected above threshold for a given survey, s, in each zone, z. The
number of individuals already includes the species' habitat-based
density (z,t) for each species and zone.
\5\ z,t is the habitat-based density for each species or
taxonomic group, t, in each zone, z.
\6\ LoEz,s,y is the level of effort in days per year, y, for
each survey type, s, in each zone, z.
---------------------------------------------------------------------------
[GRAPHIC] [TIFF OMITTED] TP05JA23.002
Observing that the resultant numbers did not make sense, BOEM
attempted to rectify the issue, by applying approximated species-
specific scaling factors (Ct).
[GRAPHIC] [TIFF OMITTED] TP05JA23.003
The result of this approach 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.
[[Page 929]]
As discussed previously, through NMFS' experience in 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 unnecessarily 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) and provided for public review through
NMFS' proposed rule (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 six 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, NMFS was aware that
new cetacean density modeling (including incorporation of new Rice's
whale data) was nearing completion, in association with the BOEM-funded
GoMMAPPS effort (see: <a href="http://www.boem.gov/gommapps">www.boem.gov/gommapps</a>). As a result, NMFS
determined that this new information (updated acoustic exposure
modeling and new cetacean density models) should be used in revising
the 2021 final rule and is the basis for the analysis conducted herein.
For purposes of the negligible impact analyses, NMFS uses the ``worst-
case'' (i.e., the maximum of the estimates from the three airgun array
configurations/sizes) species-specific exposure modeling results.
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 four species, while the others decreased from those
analyzed in the final rule.\7\
---------------------------------------------------------------------------
\7\ 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 behavioral
disruption. As such, NMFS expects any potential TTS takes to be
captured by the estimated takes by behavioral disruption (discussed
below).
Table 5--Scenario-Specific Instances of Take (by Level A and Level B Harassment) and Mean Annual Take Levels Evaluated in the 2021 Final Rule \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 1 Year 2 Year 3 Year 4 Year 5 Mean annual take
Species -------------------------------------------------------------------------------------------------------------------
A B A B A B A B A B A B
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rice's whale........................ 0 10 0 8 0 8 0 6 0 7 0 8
Sperm whale......................... 0 16,405 0 14,205 0 13,603 0 9,496 0 12,388 0 13,219
Kogia spp \2\....................... 371 10,383 337 9,313 310 8,542 209 6,238 314 8,318 308 8,559
Beaked whale \2\.................... 0 191,566 0 162,301 0 158,328 0 111,415 0 142,929 0 153,308
Rough-toothed dolphin............... 0 30,640 0 27,024 0 25,880 0 19,620 0 23,219 0 25,277
Bottlenose dolphin.................. 0 603,649 0 973,371 0 567,962 0 1,001,256 0 567,446 0 742,737
Clymene dolphin..................... 0 85,828 0 67,915 0 73,522 0 47,332 0 60,379 0 66,995
Atlantic spotted dolphin............ 0 128,299 0 183,717 0 112,120 0 191,495 0 111,305 0 145,387
Pantropical spotted dolphin......... 0 478,490 0 436,047 0 391,363 0 311,316 0 395,987 0 402,641
Spinner dolphin..................... 0 75,953 0 71,873 0 61,098 0 48,775 0 64,357 0 64,411
Striped dolphin..................... 0 33,573 0 29,275 0 27,837 0 20,136 0 26,056 0 27,375
Fraser's dolphin.................... 0 4,522 0 3,843 0 3,792 0 2,726 0 3,455 0 3,668
Risso's dolphin..................... 0 21,859 0 18,767 0 18,218 0 12,738 0 16,634 0 17,643
Melon-headed whale (Blackfish)...... 0 55,813 0 47,784 0 46,584 0 32,581 0 42,224 0 44,997
Pygmy killer whale (Blackfish)...... 0 8,079 0 6,964 0 6,764 0 4,970 0 6,277 0 6,611
False killer whale (Blackfish)...... 0 16,165 0 13,710 0 13,604 0 9,664 0 12,269 0 13,082
Killer whale (Blackfish)............ 0 60 0 56 0 50 0 42 0 52 0 52
Blackfish totals.................... 0 80,117 0 68,514 0 67,002 0 47,257 0 60,822 0 64,742
[[Page 930]]
Short-finned pilot whale............ 0 15,045 0 9,824 0 13,645 0 7,459 0 8,959 0 10,986
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ A and B refer to expected instances of take by Level A and Level B harassment, respectively, for Years 1-5. For Kogia spp., expected takes by Level
A harassment represent modeled exposures adjusted to account for aversion. For the Rice's whale, no takes by Level A harassment are predicted to
occur. Therefore, no adjustment to modeled exposures to account for aversion was necessary. For Kogia spp., exposures above Level A harassment
criteria were predicted by the peak sound pressure level (SPL) metric. For the Rice's whale, the cumulative sound exposure level (SEL) metric is used
to evaluate the potential for Level A harassment.
\2\ Kogia spp. includes dwarf and pygmy sperm whales. Beaked whales include Blainville's, Gervais', and Cuvier's beaked whales.
Table 6--Updated Scenario-Specific Instances of Take (by Level A and Level B Harassment) and Mean Annual Take Levels \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 1 Year 2 Year 3 Year 4 Year 5 Mean annual take
Species -------------------------------------------------------------------------------------------------------------------
A B A B A B A B A B A B
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rice's whale........................ 0 27 0 26 0 23 0 25 0 30 0 26
Sperm whale......................... 0 13,198 0 11,208 0 11,063 0 8,126 0 10,127 0 10,744
Kogia spp \2\....................... 192 7,272 172 6,301 165 6,104 118 4,581 164 5,776 162 6,007
Beaked whale \2\.................... 0 29,415 0 26,955 0 23,551 0 17,307 0 23,060 0 24,058
Rough-toothed dolphin............... 0 38,535 0 33,878 0 32,241 0 25,290 0 29,373 0 31,863
Bottlenose dolphin.................. 0 284,366 0 418,676 0 251,807 0 439,366 0 248,863 0 328,616
Clymene dolphin..................... 0 29,919 0 23,248 0 25,893 0 17,378 0 21,209 0 23,529
Atlantic spotted dolphin............ 0 37,080 0 34,140 0 33,126 0 34,343 0 23,906 0 32,519
Pantropical spotted dolphin......... 0 293,390 0 259,831 0 243,888 0 189,147 0 236,651 0 244,581
Spinner dolphin..................... 0 4,618 0 4,456 0 3,704 0 3,147 0 4,101 0 4,006
Striped dolphin..................... 0 56,797 0 51,623 0 46,820 0 37,449 0 47,084 0 47,955
Fraser's dolphin.................... 0 14,499 0 12,343 0 12,181 0 8,833 0 11,118 0 11,795
Risso's dolphin..................... 0 8,146 0 6,939 0 6,787 0 4,834 0 6,176 0 6,576
Blackfish \2\....................... 0 67,509 0 57,010 0 56,860 0 40,787 0 51,138 0 54,661
Short-finned pilot whale............ 0 14,330 0 9,694 0 12,836 0 7,232 0 8,734 0 10,565
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ A and B refer to expected instances of take by Level A and Level B harassment, respectively, for Years 1-5. Expected takes by Level A harassment
represent modeled exposures adjusted to account for aversion. For the Rice's whale, this adjustment means that no takes by Level A harassment are
predicted to occur. For Kogia spp., exposures above Level A harassment criteria were predicted by the peak SPL metric. For the Rice's whale, the
cumulative SEL metric is used to evaluate the potential for Level A harassment.
\2\ Kogia spp. includes dwarf and pygmy sperm whales. Beaked whales include Blainville's, Gervais', and Cuvier's beaked whales. Blackfish includes melon-
headed whale, false killer whale, pygmy killer whale, and killer whale.
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. NMFS has addressed BOEM's error to the
extent possible in the discussion provided previously (see Take
Estimation Error, wherein we relate BOEM's explanation of that 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 modeling, and many had extensive updates. 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 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 was not
as great as may have been expected on the basis of total
[[Page 931]]
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 proposed rule,
i.e., differences between Tables 5 and 6, are shown in Table 7.
Table 7--Differences in Estimated Take Numbers, 2021 Final Rule to 2022 Proposed Rule \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mean annual
Species Year 1 Year 2 Year 3 Year 4 Year 5 take
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rice's whale............................................ 17 18 15 19 23 18
Sperm whale............................................. (3,207) (2,997) (2,540) (1,370) (2,261) (2,475)
Kogia spp.\2\ (Level A)................................. (179) (165) (145) (91) (150) (146)
Kogia spp. (Level B).................................... (3,111) (3,012) (2,438) (1,657) (2,542) (2,552)
Beaked whale............................................ (162,151) (135,346) (134,777) (94,108) (119,869) (129,250)
Rough-toothed dolphin................................... 7,895 6,854 6,361 5,670 6,154 6,586
Bottlenose dolphin...................................... (319,283) (554,695) (316,155) (561,890) (318,583) (414,121)
Clymene dolphin......................................... (55,909) (44,667) (47,629) (29,954) (39,170) (43,466)
Atlantic spotted dolphin................................ (91,219) (149,577) (78,994) (157,152) (87,399) (112,868)
Pantropical spotted dolphin............................. (185,100) (176,216) (147,475) (122,169) (159,336) (158,060)
Spinner dolphin......................................... (71,335) (67,417) (57,394) (45,628) (60,256) (60,405)
Striped dolphin......................................... 23,224 22,348 18,983 17,313 21,028 20,580
Fraser's dolphin........................................ 9,977 8,500 8,389 6,107 7,663 8,127
Risso's dolphin......................................... (13,713) (11,828) (11,431) (7,904) (10,458) (11,067)
Blackfish \3\........................................... (12,608) (11,504) (10,142) (6,470) (9,684) (10,081)
Short-finned pilot whale................................ (715) (130) (809) (227) (225) (421
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Parentheses indicate negative values.
\2\ Level A harassment is not predicted to occur for any species other than the Kogia spp.
\3\ Values presented for blackfish represent the difference between the estimated take number presented in this rule for this group generically and the
sum of the species-specific values evaluated in the 2021 final rule.
NMFS cautions against interpretation of the changes presented in
Table 7 at face value for a variety of reasons. First, reasons for the
differences are difficult to interpret, as discussed in detail in the
foregoing. Second, the meaning of the differences in terms of impacts
to the affected species or stocks is similarly not as straightforward
as may be indicated by the magnitude and direction of the differences.
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 (more specifically, each of these
``takes'' representing 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 an approach to inform two important parts of the
analyses, both better 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 Letters of Authorization 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
[[Page 932]]
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 re-scaling method reduced the
overall magnitude of modeled takes for all species by a range of
slightly more than double up to ten-fold (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 should be considered in
requests for LOAs to assess whether a resulting LOA would meet the
small numbers standard. However, for the purposes of ensuring that the
take 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 take authorized for any given
species or stock over the course of the five years covered under these
regulations should not exceed the sum of the five years of take
indicated for the five years in that table. Additionally, in any given
year, the take of any species should not exceed the highest annual take
listed for any of the five years.
Table 8--Expected Total Take Numbers, Scaled \1\
----------------------------------------------------------------------------------------------------------------
Species Year 1 Year 2 Year 3 Year 4 Year 5
----------------------------------------------------------------------------------------------------------------
Rice's whale.................... 5 5 4 5 6
Sperm whale..................... 5,583 4,741 4,679 3,437 4,284
Kogia spp....................... 2,334 2,022 1,959 1,470 1,854
Beaked whale.................... 2,971 2,722 2,379 1,748 2,329
Rough-toothed dolphin........... 11,060 9,723 9,253 7,258 8,430
Bottlenose dolphin.............. 81,613 120,160 72,269 126,098 71,424
Clymene dolphin................. 8,587 6,672 7,431 4,987 6,087
Atlantic spotted dolphin........ 10,642 9,798 9,507 9,856 6,861
Pantropical spotted dolphin..... 84,203 74,571 69,996 54,285 67,919
Spinner dolphin................. 1,325 1,279 1,063 903 1,177
Striped dolphin................. 16,301 14,816 13,437 10,748 13,513
Fraser's dolphin................ 4,161 3,543 3,496 2,535 3,191
Risso's dolphin................. 2,403 2,047 2,002 1,426 1,822
Blackfish....................... 19,915 16,818 16,774 12,032 15,086
Short-finned pilot whale........ 4,227 2,860 3,787 2,134 2,576
----------------------------------------------------------------------------------------------------------------
\1\ Scalar ratios were applied to values in Table 6 as described in the 2018 notice of proposed rulemaking to
derive scaled take numbers shown here.
Proposed 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 least practicable adverse impact 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 (hereinafter
referred to as ``LPAI'' or ``least practicable adverse impact''). NMFS
does not have a regulatory definition for least practicable adverse
impact. 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 least practicable adverse impact upon the affected
species or stocks and their habitat (50 CFR 216.104(a)(11)). We note
that in some cases, certain mitigation may be necessary in order to
make a ``negligible impact'' finding for an affected species or stock,
which is a fundamental requirement of issuing an authorization--in
these cases, consideration of practicability may be a lower priority
for decision-making if impacts to marine mammal species or stocks would
not be negligible in the measure's absence. In the Mitigation section
of the 2021 final rule, NMFS included a detailed description of our
interpretation of the LPAI standard and how it should be applied, and
we refer readers to that discussion.
In summary, in evaluating how mitigation may or may not be
appropriate to ensure the least practicable adverse impact on species
or stocks and their habitat, as well as subsistence uses where
applicable, NMFS considers 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.
(2) The practicability of the measures for applicant
implementation. Practicability of implementation may consider such
things as cost, impact on
[[Page 933]]
activities, personnel safety, and practicality of implementation.
Application of the Least Practicable Adverse Impact Standard in This
Action
In carrying out the MMPA's mandate for this action, NMFS applies
the previously described 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. The effects of concern (i.e., those with the potential
to adversely impact species or stocks and their habitat), addressed
previously in the Potential Effects of the Specified Activity on Marine
Mammals and Their Habitat section of the 2018 notice of proposed
rulemaking, include auditory injury, severe behavioral reactions,
disruptions of critical behaviors, and to a lesser degree, masking and
impacts on acoustic habitat (see discussion of this concept in the
``Anticipated Effects on Marine Mammal Habitat'' section in the 2018
notice of proposed rulemaking).
Our prior 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 with an understanding of the drawbacks or costs of
these requirements. In addition, we evaluated time-area restrictions
that would avoid or reduce both acute and chronic impacts, 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. 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 also recognized that instantaneous
protocols, such as shutdown requirements, are not capable of avoiding
all acute effects, are not 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 considered
measures that may or may not be appropriate for other activities (e.g.,
time-area restrictions specific to the surveys discussed herein).
In order to satisfy the MMPA's least practicable adverse impact
standard, NMFS' 2021 rule evaluated 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
original proposed rule (83 FR 29212, June 22, 2018), and mitigation
requirements included in the incidental take regulations were fully
described in the notice of issuance for the final rule (86 FR 5322,
January 19, 2021).
For this proposed rule, NMFS considered additional mitigation for
this action in light of the updated take estimates. Based on that
evaluation, we have preliminarily determined that the current
regulations promulgated under the 2021 final rule satisfy the least
practicable adverse impact standard, and therefore, we do not propose
changes to those regulations. Because the proposed mitigation
requirements for this action are the same as those described in the
notice of issuance for the final rule (86 FR 5322, January 19, 2021),
we do not repeat the description of the required mitigation.
Below, we include additional discussion supporting the least
practical adverse impact finding as it relates to Rice's whales, given
the increase in estimated take relative to the 2021 final rule and
other new information. For other species, despite slight increases in
estimated take (for three species) and increases in evaluated risk (for
other species) since 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 least
practicable adverse impact 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--As discussed previously in this document, the Rice's
whale ``core habitat area'' considered in the 2018 notice of proposed
rulemaking was designated as between the 100- and 400-m isobaths, from
87.5[deg] W to 27.5[deg] N (Figure 3). That core habitat area was
considered in the 2018 notice of proposed rulemaking as a potential
restriction area, but because the area was entirely located in the
GOMESA moratorium area removed from consideration for the rule, the
core habitat area was no longer relevant for consideration as
mitigation in the 2021 final rule.
As described previously, NMFS has developed an updated description
of Rice's whale core habitat area (Figure 3). The updated process for
describing ``core habitat'' incorporated a more precautionary approach
to addressing uncertainty associated with both the location of observed
whales as well as to account for the possible movement whales could
make in any one direction from an observed sighting, i.e., inclusion of
the 30-km total buffer discussed previously. As a result of the
addition of this buffer to the newly defined polygon encompassing all
whale observations and tag locations in the core habitat region, the
updated core habitat area now overlaps slightly within the area covered
through the scope of the rule. Approximately 5 percent of the updated
core habitat area now overlaps the geographic scope of the rule (as
defined by the petitioner, BOEM). In addition, new information
regarding potential Rice's whale occurrence outside of the core habitat
area, based on passive acoustic detections (Soldevilla et al., 2022),
is now available. Information supporting the importance of a core
habitat area for Rice's whales has not changed from the 2021 final
rule. We provide discussion of this information in the following
paragraphs.
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Rice's whales form a small and resident population in the
northeastern GOM, with a highly restricted geographic range and a very
small population abundance--determined by the status review team to be
``at or below the near-extinction population level'' (Rosel et al.,
2016). Aside from the restricted distribution and small population, the
whales face a significant suite of anthropogenic threats, one of which
is noise produced by airgun surveys.
While various population abundance estimates are available (e.g.,
Garrison et al., 2022; Hayes et al., 2020; Roberts et al., 2016; Dias
and Garrison, 2016), the population abundance was almost certainly less
than 100 prior to the DWH oil spill. NOAA estimated that, as a result
of that event, 48 percent of the population may have been exposed to
DWH oil, with 17 percent killed and 22 percent of females experiencing
reproductive failure. The best estimate for maximum population
reduction was 22 percent, with an estimated 69 years to recovery (to
the precarious status prior to the DWH oil spill) (DWH MMIQT, 2015). It
is considered likely that Rice's whale habitat previously extended to
shelf and slope areas of the western and central GOM similar to where
they are found now in the eastern GOM, and that anthropogenic
activity--largely energy exploration and production--concentrated in
those areas could have resulted in habitat abandonment (Reeves et al.,
2011; Rosel and Wilcox, 2014). Further, the population exhibits very
low levels of genetic diversity, and based on significant genetic
mitochondrial DNA divergence from Bryde's whales worldwide, the former
GOM Bryde's whale was recognized as a separate species (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), which has been exacerbated by the effects of the DWH oil
spill. 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). NMFS considered a restriction
within core habitat (as previously defined) to protect Rice's whales
because of their hearing sensitivity in the lower frequency range
(which makes them generally more susceptible to incurring effects from
airgun noise than other taxa in the GOM); the potential impacts to
important behavioral functions such as feeding, breeding, and raising
young; their dangerously low population size; and other issues
discussed previously.
NMFS' 2018 proposed rule proposed a seasonal restriction on survey
activity in the core habitat area considered therein, but also
requested comment on a range of alternatives (including a year-round
restriction). That proposal, and associated alternatives, were offered
for public comment in context of the significantly greater predicted
take numbers evaluated in the 2018 proposed rule and the complete
overlap of the original project area with the core habitat area prior
to the removal of the
[[Page 935]]
GOMESA area. While the take numbers presented here are greater than
those evaluated in the 2021 final rule, they are significantly lower in
relation to those in the 2018 proposed rule. Predicted take numbers
across the three analyses are shown in Table 9. In addition, the 2018
proposed rule analysis included up to several instances of Level A
harassment per year, in the form of permanent threshold shift. In
contrast, neither the 2021 final rule nor this proposed rule include
predicted instances of Level A harassment.
Table 9--Comparison of Analyzed Rice's Whale Take
----------------------------------------------------------------------------------------------------------------
2018 proposed 2021 final 2022 proposed
rule rule rule
----------------------------------------------------------------------------------------------------------------
5-year total.................................................... 2,310 39 132
Annual maximum.................................................. 572 10 30
----------------------------------------------------------------------------------------------------------------
As noted above, the proposed restriction, and alternatives thereto,
were no longer relevant due to the changed geographic scope of the 2021
final rule. We now consider the effectiveness and practicability of a
potential restriction covering the approximately 5 percent of core
habitat (updated) that overlaps with the geographic scope of this rule,
as well as of other areas that could be considered important habitat
for Rice's whales.
As discussed in the 2018 proposed rule, a restriction on (or
absence of) survey activity in core habitat would be expected to
protect Rice's whales and their habitat 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 core habitat area. The absence of survey activity in
the area would not only largely avoid Level B harassment of Rice's
whales, but also very importantly minimize other acoustic effects such
as masking and loss of communication space.
However, the significant concern that led NMFS to consider such a
restriction through the 2018 proposed rule has largely been alleviated
through the reduction in predicted take numbers. Although predicted
take numbers have increased relative to the 2021 final rule (annual
average Level B harassment events of 26 versus 8), expected takes
remain significantly less than those considered in that 2018 analysis
(annual average of 462, plus some expected potential for Level A
harassment to occur)--an almost 18-fold reduction. Moreover, the
functional absence of survey activity in the eastern GOM, and within
Rice's whale core habitat, means that the anticipated protection
afforded by the previously proposed restriction has been substantively
achieved by virtue of the change in scope for the 2021 final rule
(which is unchanged for this proposed action). Although the updated
core habitat area now slightly overlaps with the geographic scope of
the rule (5 percent of defined core habitat overlaps the area
considered as part of this rule), we note that the update to the core
habitat description is not the result of additional Rice's whale
sightings necessitating the expanded description, but rather through
the incorporation of additional precaution in defining the area within
which existing Rice's whale sightings and tag locations suggest that
whales could occur (i.e., a 30-km buffer has been added, as discussed
in the Description of Marine Mammals in the Area of the Specified
Activities section). As a result of these considerations, NMFS has
determined that a restriction on survey activity within the portion of
the updated core habitat area that occurs within scope of the rule is
not warranted. NMFS requests comment on this determination.
Although the core habitat area is largely no longer relevant under
the updated geographic scope of the specified activity and this rule,
the discussion above is still important to describe NMFS' work to
identify appropriate mitigation in this rulemaking. In addition, we
acknowledge that some whales are likely to be present at locations
other than within the core habitat area, and we considered additional
information in order to evaluate whether a different closure area 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.
Outside of the core habitat area, a NOAA survey reported
observation of a Rice's whale in the western GOM in 2017 (NMFS, 2018).
There had not previously been a 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.
Prior to the 2017 sighting, which was confirmed as a Rice's whale, it
was considered unlikely that the 1992 sightings were of Rice's whales.)
In addition, there are occasional sightings by protected species
observers (PSOs) of baleen whales in the GOM. These sightings are
typically of other, vagrant species, are in habitat considered
unsuitable for Rice's whale (e.g., deep water), and/or are unresolved
taxonomically. Of 13 unconfirmed Bryde's-like whale PSO sightings that
occurred along the northwestern GOM shelf-break from 2010-2014, Rosel
et al. (2021) found that there were 4 potential Rice's whale
observations (i.e., that could neither be verified nor ruled out as
Rice's whale sightings), all within the 200-400 m isobaths.
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In addition, Soldevilla et al. (2022) deployed autonomous passive
acoustic recorders at five sites along the northwestern 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 five northwestern GOM 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 their known core
habitat in the northeastern GOM 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 was in 408 m water depth). Data were successfully collected at
four of the five sites; of these 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, and it remains unknown whether
animals are moving between the northwestern and northeastern sites or
whether these represent different groups of animals (Soldevilla et al.,
2022). The rate of call detections throughout the year is considerably
higher in the eastern GOM than at the western GOM site where calls were
most commonly detected, with at least 8.3 calls/hour among four eastern
GOM sites over 110 deployment days (Rice et al., 2014) compared to 0.27
calls/hour over the 299-day deployment at the western GOM site where
calls were detected most frequently. Approximately 2,000 total calls
were detected at the 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). Although it should be noted that ambient
noise conditions were higher at the western GOM site, influencing
maximum detection range, 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, the study authors assess
that there seem to be fewer whales or more sparsely spaced whales in
the western GOM compared to the eastern GOM, with calls present on
fewer days, lower call detection rates, and far fewer call detections
in the western GOM.
The passive acoustic data discussed above provide evidence for the
persistent occurrence of at least some individual Rice's whales over a
broader distribution in the GOM than previously understood. However,
overall, Rice's whale observations remain consistently located within
the eastern GOM core habitat area, with few whales sighted
[[Page 937]]
elsewhere despite a large amount of dedicated cetacean survey effort
that covered both continental shelf and oceanic waters. Whales have
been sighted in the core habitat area in all seasons, and all
indications are that the whales inhabit this area year-round as a
resident population. A tagged whale remained within the area for the
entire time the tag was active (38 days). Therefore, while we expect
that some individual Rice's whales occur outside the core habitat area
and/or that whales from the eastern GOM occasionally travel outside the
area, the currently available data support NMFS' determination that the
area currently considered core habitat is an adequate representation.
NMFS produced a regulatory impact analysis (RIA) in support of the
2018 proposed rule, which evaluated potential costs associated with a
range of area-based activity restrictions (available online at:
<a href="http://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico">www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico</a>). Although that
analysis did not directly evaluate a potential closure of the area that
might be considered here as a Rice's whale protected area, i.e.,
potentially suitable habitat in the central and western GOM outside of
known Rice's whale core habitat, it provided a useful framework for
considering practicability in an assessment of potential restrictions
in the northeastern GOM. That analysis concluded that the direct
compliance costs of the rule would represent a small increase in oil
and gas development costs overall and, therefore, would be unlikely to
result in materially reduced oil and gas activities in the GOM.
However, 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
report 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. NMFS cannot predict factor
(1) and does not have complete information regarding factor (3) (though
the analysis 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.
Historical Rice's whale habitat, which is also generally modeled as
being suitable habitat (Roberts et al., 2016; Garrison et al. 2022),
generally consists of the aforementioned strip of continental shelf
waters within the 100-400 m isobaths. Salinity and surface water
velocity are also likely predictive of potential Rice's whale
occurrence (Garrison et al., 2022), 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) 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 survey effort during NMFS'
experience in implementing this rule has occurred. The 2018 proposed
rule RIA considered the economic impacts of a prospective closure area
in deeper waters of the central GOM. The evaluated area was designed to
be of benefit to 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 whales are expected to be found.
As such, the RIA analysis likely overestimates the potential impacts of
a central GOM closure within a portion of the shelf waters favored by
Rice's whales in their known habitat. However, the analysis of deep-
water closures in the central GOM suggested the possibility that the
closure could affect the broader contribution of the GOM to U.S. oil
and gas activity, with shifts in effort potentially reducing domestic
oil and gas production, industry income, and employment, ultimately
concluding that the economic impact on the regional economy could be
significant. A key consideration in this finding relates to factor (4),
as the analyzed closure was year-round. Similarly, there is no
information to support a temporal component to design of a potential
Rice's whale closure and, therefore, a closure would appropriately be
year-round. As operators have no ability to plan around a year-round
closure, this aspect exacerbates the potential for effects on oil and
gas productivity in the GOM.
In summary, the foregoing preliminarily supports (1) that there is
no clearly defined important habitat with known occupation and usage
patterns outside the existing core habitat area that would
appropriately be subject to a restriction on survey activity; and (2)
the potential that a central GOM closure would have significant
economic impacts. During implementation of the existing rule, NMFS has
issued three LOAs in association with surveys occurring roughly within
this area of the central GOM (87 FR 55790, October 1, 2022; 87 FR
43243, July 20, 2022; 87 FR 42999, July 19, 2022). Based on these
surveys, there is a possibility that the closure could affect the
broader contribution of the GOM to future U.S. oil and gas activity.
Given the relatively low level of take predicted to occur for Rice's
whales in context of the de facto protection afforded through the
circumscribed scope of the rule (i.e., the rule does not cover the bulk
of Rice's whale core habitat, where whales are generally anticipated to
occur, and no survey activity is expected to occur in the eastern GOM),
NMFS has preliminarily determined that no additional mitigation is
necessary or appropriate in order to effect the least practicable
adverse impact 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 proposed rule. Based on
our evaluation of these measures, we have preliminarily affirmed that
the required mitigation measures contained in the current regulations
provide the means of effecting the least practicable adverse impact on
marine mammal species or stocks and their habitat, paying particular
attention to rookeries, mating grounds, and areas of similar
significance.
Proposed Monitoring and Reporting
In order to issue an LOA 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 do not propose changes to the current LOA reporting
requirements, which have been sufficient to date. Accordingly, the
monitoring and
[[Page 938]]
reporting requirements for this proposed 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 has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). 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 and related mitigation measures, as well as potential
risk due to entanglement and contaminant spills, was 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 proposed 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 proposed 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 provides a conservative but
reasonable best estimate of potential acute noise exposure events that
may result from the described suite of activities.
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 (discussed in detail in
the 2018 notice of proposed rulemaking) to evaluate potential effects
of aggregated discrete acoustic exposure events (i.e., proposed
geophysical survey activities) on marine mammals. This risk assessment
framework, which is one component of the overall negligible impact
analysis, was described by Southall et al. (2017) (available online at:
<a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-oil-and-gas">www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-oil-and-gas</a>), and discussed in detail in the 2018
notice of proposed rulemaking. That framework, which was subsequently
refined in response to public comment and in consideration of the
updated scope of the activity (as discussed in the notice of issuance
of the 2021 final rule), has not changed and is not described in detail
in this notice. Please review the 2018 proposed and 2021 final rule
notices, as well as Southall et al. (2017), for further detail. This
framework continues to represent the best available methodology for
assessing relative risk, and we incorporate the framework and its
results into this analysis.
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 potential severity of effect on a stock and 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 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. Overall ratings are then considered in conjunction with the
required mitigation (and any additional relevant contextual
information) to ultimately inform our determinations. Elements of this
approach are subjective and relative within the context of this program
of projected actions and, overall, the analysis necessarily requires
the application of professional judgment.
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 have revisited the risk
assessment methodology for all species, and present updated information
below. Specifically, as discussed below, severity ratings are the
product of
[[Page 939]]
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., 2022), we revisit 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 revisit 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 four species: Rice's whale, Fraser's dolphin, rough-toothed
dolphin, and striped dolphin (though it should be noted that overall
relative risk ratings remained static for Rice's whale and Fraser's
dolphin). Whether estimated take numbers increased for each of the four
species within the ``blackfish'' category is unknown under NMFS'
proposed approach to estimating take numbers. However, overall relative
risk ratings increased slightly for most species. Of the species for
which evaluated take decreased, relative risk ratings remained static
(or declined) for the sperm whale, beaked whales, bottlenose dolphin,
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 existing negligible
impact analyses for the sperm whale, all beaked whale species,
bottlenose dolphin, and spinner dolphin. Please see the notice of
issuance for the current rule (86 FR 5322, January 19, 2021) for
analysis related to these species, which we incorporate by reference to
this proposed rule. We revisit here the negligible impact analyses for
those species for which evaluated take numbers increased and/or for
which the assessed relative risk rating increased.
The risk assessment framework 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 these 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'' and then brings together the results of
implementation of the framework, these additional factors, and the
anticipated effects of the mitigation to summarize the negligible
impact analysis for each of the species considered here. The risk
assessment analysis below is performed for 2 representative years, with
Year 1 representing a relatively high-effort scenario and Year 4
representing a moderate-effort scenario. Please see Table 2 for details
regarding BOEM's level of effort projections.
Severity of Effect
As described above in Estimated Take, a significant model
assumption was that populations of animals were reset for each 24-hr
period. Exposure estimates for the 24-hr 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, using such a scaling process is appropriate in
order to evaluate the likely severity of the predicted exposures and to
estimate take for the purposes of LOA applications and predicting the
number of individual marine mammals taken during the course of a single
survey (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 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 10.
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.
Table 10--Severity Assessment
----------------------------------------------------------------------------------------------------------------
Zone 1 \1\ Zone 2 Zone 3 Zone 4 \1\ Zone 5 Zone 6 Zone 7
Species ---------------------------------------------------------------------------------
H M H M H M H M H M H M H M
----------------------------------------------------------------------------------------------------------------
Rice's whale.................. VL VL VL VL VL VL VL VL VL VL VL VL n/a n/a
Sperm whale................... n/a n/a n/a n/a n/a n/a VL VL H H M L L L
Kogia spp..................... n/a n/a n/a n/a n/a n/a VL VL H M M L L VL
Beaked whales................. n/a n/a n/a n/a n/a n/a VL VL VH VH VL VL VL VL
Rough-toothed dolphin......... VL VL L M VL VL VL VL H H M L L L
Bottlenose dolphin............ VL VL L M VL VL VL VL M M L VL n/a n/a
Clymene dolphin............... n/a n/a n/a n/a n/a n/a VL VL H H M L L VL
Atlantic spotted dolphin...... VL VL M H VL VL VL VL H M M L n/a n/a
[[Page 940]]
Pantropical spotted dolphin... n/a n/a n/a n/a n/a n/a VL VL H H M L L VL
Spinner dolphin............... n/a n/a n/a n/a n/a n/a VL VL H H n/a n/a VL VL
Striped dolphin............... n/a n/a n/a n/a n/a n/a VL VL H H M L L VL
Fraser's dolphin.............. VL VL VL VL VL VL VL VL H H M L L L
Risso's dolphin............... n/a n/a VL VL n/a n/a VL VL H M M L L VL
Short-finned pilot whale...... n/a n/a VL VL VL VL VL VL H M M L VL VL
Blackfish..................... n/a n/a n/a n/a n/a n/a VL VL H H M L L L
----------------------------------------------------------------------------------------------------------------
H = Year 1 (representative high effort scenario); M = Year 4 (representative moderate effort scenario).
n/a = less than 0.05 percent of GOM-wide population predicted in zone.
VL = very low; L = low; M = moderate; H = high; VH = very high.
\1\ No activity would occur in Zone 1, and no activity is projected in Zone 4 under the high effort scenario.
With no activity in a zone, severity is assumed to be very low.
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 proposed
activity and how it relates to the species in question and the
environment within the specified area were required. Factors considered
in the vulnerability assessment 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 11. Note that, as there are certain species-
specific elements of the vulnerability assessment, we evaluated and
present results for 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 the blackfish group as a whole.
Table 11--Vulnerability Assessment
------------------------------------------------------------------------
Zone
Species -----------------------------------------
1 2 3 4 5 6 7
------------------------------------------------------------------------
Rice's whale.................. H H M H H H n/a
Sperm whale................... n/a n/a n/a M H M M
Kogia spp..................... n/a n/a n/a L L L L
Beaked whale.................. n/a n/a n/a L L L L
Rough-toothed dolphin......... L L L L L L L
Bottlenose dolphin............ L L L VL L VL n/a
Clymene dolphin............... n/a n/a n/a L L L L
Atlantic spotted dolphin...... M M L L L L n/a
Pantropical spotted dolphin... n/a n/a n/a L L L L
Spinner dolphin............... n/a n/a n/a L L n/a L
Striped dolphin............... n/a n/a n/a L L L L
Fraser's dolphin.............. L L VL L L L L
Risso's dolphin............... n/a L n/a M M M L
Melon-headed whale............ n/a n/a n/a L M L L
Pygmy killer whale............ n/a n/a n/a L L L L
False killer whale............ n/a n/a n/a L L L L
Killer whale.................. n/a n/a n/a L L L L
Short-finned pilot whale...... n/a M L M M M L
------------------------------------------------------------------------
n/a = less than 0.05% of GOM-wide population predicted in zone.
VL = very low; L = low; M = moderate; H = high; VH = very high.
Risk
In the final step of the framework, severity and vulnerability
ratings are integrated to provide relative impact ratings of overall
risk. 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. The matrix is
shown in Table 2 of Southall et al. (2017).
Table 12 provides relative impact ratings by zone, and Table 13
provides GOM-wide relative impact ratings, for overall risk associated
with predicted takes, for representative high and moderate effort
scenarios.
[[Page 941]]
Table 12--Overall Evaluated Risk by Zone and Activity Scenario
----------------------------------------------------------------------------------------------------------------
Zone 1 \1\ Zone 2 Zone 3 Zone 4 \1\ Zone 5 Zone 6 Zone 7
Species ---------------------------------------------------------------------------------
H M H M H M H M H M H M H M
----------------------------------------------------------------------------------------------------------------
Rice's whale.................. L L L L L L L L L L L L n/a n/a
Sperm whale................... n/a n/a n/a n/a n/a n/a L L VH VH M L L L
Kogia spp..................... n/a n/a n/a n/a n/a n/a VL VL H M M L L VL
Beaked whale.................. n/a n/a n/a n/a n/a n/a VL VL VH VH VL VL VL VL
Rough-toothed dolphin......... VL VL L M VL VL VL VL H H M L L L
Bottlenose dolphin............ VL VL L M VL VL VL VL H M M VL n/a n/a
Clymene dolphin............... n/a n/a n/a n/a n/a n/a VL VL H H M L L VL
Atlantic spotted dolphin...... L L M H VL VL VL VL H M M L n/a n/a
Pantropical spotted dolphin... n/a n/a n/a n/a n/a n/a VL VL H H M L L VL
Spinner dolphin............... n/a n/a n/a n/a n/a n/a VL VL H H n/a n/a VL VL
Striped dolphin............... n/a n/a n/a n/a n/a n/a VL VL H H M L L L
Fraser's dolphin.............. VL VL VL VL VL VL VL VL H H M L L L
Risso's dolphin............... n/a n/a VL VL n/a n/a L L H H M L L VL
Short-finned pilot whale...... n/a n/a L L VL VL L L H M M L VL VL
Blackfish..................... n/a n/a n/a n/a n/a n/a VL VL H H M L L L
----------------------------------------------------------------------------------------------------------------
H = Year 1 (representative high effort scenario); M = Year 4 (representative moderate effort scenario).
n/a = less than 0.05 percent of GOM-wide population predicted in zone.
VL = very low; L = low; M = moderate; H = high; VH = very high.
\1\ No activity would occur in Zone 1, and no activity is projected in Zone 4 under the high effort scenario.
With no activity in a zone, severity is assumed to be very low.
Table 13--Overall Evaluated Risk by Projected Activity Scenario, GOM-
Wide
------------------------------------------------------------------------
High effort Moderate effort
Species scenario (year 1) scenario (year 4)
------------------------------------------------------------------------
Rice's whale.................... Low (0)........... Low (0).
Sperm whale..................... Low/Moderate \1\ Low (0).
(0).
Kogia spp....................... Low/Moderate \1\ Very Low/Low \1\
(+0.5). (+0.5).
Beaked whales................... Very Low (-2.5)... Very Low (-1.5).
Rough-toothed dolphin........... Low (+1).......... Low (+1).
Bottlenose dolphin (shelf/ Very low (0)...... Very low (0).
coastal).
Bottlenose dolphin (oceanic).... Very low (0)...... Very low (0).
Clymene dolphin................. Low/Moderate \1\ Very Low/Low \1\
(+0.5). (0).
Atlantic spotted dolphin........ Low/Moderate \1\ Low (0).
(+0.5).
Pantropical spotted dolphin..... Low/Moderate \1\ Very Low/Low \1\
(+0.5). (+0.5).
Spinner dolphin................. Very low (0)...... Very low (0).
Striped dolphin................. Low/Moderate \1\ Low (+1).
(+0.5).
Fraser's dolphin................ Very low (0)...... Very low (0).
Risso's dolphin................. Low (+1).......... Low (+1).
Short-finned pilot whale........ Low (0)........... Low (+0.5).
Blackfish....................... Low/Moderate Low (+1).
(+1.5).
------------------------------------------------------------------------
\1\ For these ratings, the median value across zones for the scenario
fell between two ratings.
\2\ In the 2021 final rule, the four ``blackfish'' species were each
independently evaluated as having ``very low'' relative risk.
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 12), to describe a GOM-wide
risk rating for each of the representative activity scenarios (Table
13).
As noted above, for sperm whale, beaked whales, bottlenose dolphin,
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, 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. (Rice's whale core habitat largely overlaps Zone 1,
which is not within scope of this rule.) Areas with consistently high
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 that zone 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 in the following (excepting Rice's whale (both
scenarios) as well as 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
species (and ``very high'' relative risk was not identified under
either
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scenario in any zone for any of the species evaluated further in the
following). 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 13
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 four 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
Proposed Mitigation sections of the 2018 notice of proposed rulemaking,
2021 notice of issuance of the final rule, and this proposed 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 a momentary 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 described
above. Each animat modeled has a record or time history of received
levels of sound over the course of the modeled 24-hr period. For
example, for the four ``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-hr period that an animal would
spend with received levels above 160 dB and between 140 and 160 dB in
Table 14. This information considered is unchanged from the 2021 notice
of issuance for the 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-hr
exposure estimates by the total number of survey days versus modeling
for a full 30-day survey duration for six 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-hr 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
and that it is more likely some individuals would be exposed on fewer
days and some on more. Table 14 reflects the average days exposed above
threshold for the indicated species having applied the scalar ratios
described previously.
Table 14--Time in Minutes (Per Day) Spent Above Thresholds (50th Percentile) and Average Number of Days Individuals Taken During 30-Day Survey
--------------------------------------------------------------------------------------------------------------------------------------------------------
Survey type and time (min/day) above Survey type and time (min/day) above Average number
160 dB rms (50% take) 140 dB rms (10% take) of days
Species -------------------------------------------------------------------------------- ``taken''
during 30-day
2D 3D NAZ 3D WAZ Coil 2D 3D NAZ 3D WAZ Coil survey
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rice's whale............................................ 7.6 18.2 6.8 21.4 61.7 163.5 55.4 401.1 5.3
Sperm whale............................................. 5.2 10.3 4.0 20.7 12.0 31.8 10.7 25.2 2.4
Kogia spp............................................... 3.2 7.9 2.8 15.3 7.6 19.0 6.7 13.9 3.1
Beaked whale............................................ 6.0 12.4 4.4 24.0 16.2 39.7 14.1 31.1 9.9
Rough-toothed dolphin................................... 3.0 6.3 2.5 11.4 11.2 27.6 10.2 20.9 3.5
Bottlenose dolphin...................................... 4.5 11.7 4.0 16.8 22.0 54.6 19.7 53.2 3.5
Clymene dolphin......................................... 1.8 3.9 1.6 8.7 8.0 21.1 7.2 20.4 3.5
Atlantic spotted dolphin................................ 7.0 16.0 6.5 25.7 23.4 58.1 20.9 49.3 3.5
Pantropical spotted dolphin............................. 1.8 4.1 1.6 8.7 8.1 21.0 7.1 22.2 3.5
Spinner dolphin......................................... 3.2 8.5 2.7 16.4 12.4 31.0 10.8 22.8 3.5
Striped dolphin......................................... 1.8 4.0 1.6 8.5 8.0 21.0 7.2 21.3 3.5
Fraser's dolphin........................................ 2.8 6.4 2.4 13.8 9.4 24.2 8.4 24.0 3.5
Risso's dolphin......................................... 3.4 8.4 2.9 15.3 13.8 37.7 12.2 31.5 3.5
Melon-headed whale...................................... 2.6 5.9 2.2 13.1 9.3 24.2 8.3 24.0 3.4
[[Page 943]]
Pygmy killer whale...................................... 1.8 3.6 1.4 7.1 7.3 18.5 6.6 17.3 3.4
False killer whale...................................... 2.4 4.9 1.9 9.3 8.8 22.0 8.0 17.8 3.4
Killer whale............................................ 2.7 6.1 3.3 12.0 16.8 46.1 14.9 73.6 3.4
Short-finned pilot whale................................ 3.3 8.1 2.9 17.5 10.9 27.4 9.8 20.8 3.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
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 s
[…truncated; see source link]Indexed from Federal Register on January 5, 2023.
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