Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey in the Nauru Basin of Greater Micronesia in the Northwest Pacific Ocean, 101555-101568 [2024-29552]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 89, Number 241 (Monday, December 16, 2024)]
[Notices]
[Pages 101555-101568]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-29552]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XE461]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Marine Geophysical Survey in the 
Nauru Basin of Greater Micronesia in the Northwest Pacific Ocean

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

ACTION: Notice; issuance of an incidental harassment authorization.

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SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that NMFS has issued an incidental harassment authorization (IHA) to 
the Scripps Institution of Oceanography (SIO) to incidentally harass 
marine mammals during survey activities associated with a marine 
geophysical survey in the Nauru Basin of greater Micronesia in the 
northwest (NW) Pacific Ocean.

DATES: This authorization is effective from December 11, 2024 through 
December 10, 2025.

ADDRESSES: Electronic copies of the application and supporting 
documents,

[[Page 101556]]

as well as a list of the references cited in this document, may be 
obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. In case of problems accessing these documents, please call 
the contact listed below.

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

SUPPLEMENTARY INFORMATION:

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 specific 
geographic region if certain findings are made and either regulations 
are proposed or, if the taking is limited to harassment, a notice of a 
proposed IHA is 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 in shorthand as 
``mitigation''); and 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.

Summary of Request

    On June 6, 2024, NMFS received a request from the SIO for an IHA to 
take marine mammals incidental to a marine geophysical survey in the 
Nauru Basin of greater Micronesia in the NW Pacific Ocean. The 
application was deemed adequate and complete on July 30, 2024. SIO's 
request is for take of 27 species of marine mammals, by Level B 
harassment only. Neither SIO nor NMFS expect serious injury or 
mortality to result from this activity and, therefore, an IHA is 
appropriate. There are no changes from the proposed IHA to the final 
IHA.

Description of Activity

    Researchers from the Woods Hole Oceanographic Institution (WHOI) 
and University of Houston, with funding from the National Science 
Foundation (NSF), and implementation by SIO, plan to conduct a low-
energy marine seismic survey using airguns as the acoustic source from 
the research vessel (R/V) Sikuliaq (Sikuliaq), which is owned by NSF 
and operated by the University of Alaska Fairbanks (UAF). The planned 
survey will occur in the Nauru Basin of greater Micronesia in the NW 
Pacific Ocean from approximately December 2024 to January 2025. The 
planned survey will occur in International Waters and within the 
Exclusive Economic Zone (EEZ) of the Republic of Marshall Islands, in 
water depths ranging from approximately 4,000-6,000 meters (m). To 
complete this 2-dimensional (2-D) multi-channel seismic (MCS) 
reflection survey, the Sikuliaq will tow a 4-airgun array with a total 
discharge volume of ~420 cubic inches (in\3\) at a depth of 3 m, 
operated by marine technicians from SIO. The airgun array receiver will 
consist of a 1,200 m long solid-state hydrophone streamer. The airguns 
will fire at a shot interval of 30 m. Approximately 3,158 kilometers 
(km) of seismic acquisition is planned. Airgun arrays will introduce 
underwater sounds that may result in take, by Level B harassment, of 
marine mammals.
    A detailed description of the planned geophysical survey was 
provided in the Federal Register notice of the proposed IHA (89 FR 
81429, October 8, 2024). Since that time, no changes have been made to 
the planned survey activities. Therefore, a detailed description is not 
provided here. Please refer to that Federal Register notice for the 
description of the specified activity.

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to SIO was published in 
the Federal Register on October 8, 2024 (89 FR 81429). That notice 
described, in detail, SIO's activity, the marine mammal species that 
may be affected by the activity, and the anticipated effects on marine 
mammals. In that notice, we requested public input on the request for 
authorization described therein, our analyses, the proposed 
authorization, and any other aspect of the notice of proposed IHA, and 
requested that interested persons submit relevant information, 
suggestions, and comments. The proposed notice was available for a 30-
day public comment period. NMFS received no public comments.

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, instead of reprinting the information. Additional 
information about these species (e.g., physical and behavioral 
descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species). NMFS refers the reader to the 
aforementioned source for general information regarding the species 
listed in table 1.
    The populations of marine mammals found in the survey area do not 
occur within the U.S. EEZ and therefore, are not assessed in NMFS' 
Stock Assessment Reports (SAR). For most species, there are no stocks 
defined for management purposes in the survey area, and NMFS is 
evaluating impacts at the species level and ranges for most species 
evaluated here are considered to be the North Pacific. As such, 
information on potential biological removal level (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) and annual levels of serious injury and mortality from 
anthropogenic sources are not available for these marine mammal 
populations. Abundance estimates for marine mammals in the survey 
location were calculated using density data for marine mammals from a 
U.S. Navy Technical Report for the region (DoN, 2018). The area covered 
in this report include the Mariana Islands Training and Testing (MITT) 
Study Area, within approximately 6-23[deg] N, 122-150[deg] E, and the 
transit corridor which spans from the MITT Study Area to the 
International Date Line. These abundance estimates are considered the 
best scientific information available on the abundance of marine mammal 
populations in the area.
    Table 1 lists all species that occur in the survey area that may be 
taken as a result of the planned survey and summarizes information 
related to the population, including regulatory status

[[Page 101557]]

under the MMPA and Endangered Species Act (ESA).

                          Table 1--Species Likely Impacted by the Specified Activities
----------------------------------------------------------------------------------------------------------------
                                                                                     ESA/MMPA
                                                              Stock/distinct         status;
            Common name                Scientific name      population segment   strategic (Y/N)   Abundance \2\
                                                                   (DPS)               \1\
----------------------------------------------------------------------------------------------------------------
                             Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
    Blue Whale....................  Balaenoptera musculus  NA..................  E, D, Y                     150
    Bryde's Whale.................  Balaenoptera edeni...  NA..................  -, -, N                   1,596
    Fin Whale.....................  Balaenoptera physalus  NA..................  E, D, Y                      46
    Humpback Whale................  Megaptera              Western North         E, D, Y                   2,673
                                     novaeangliae.          Pacific DPS.
                                                           Oceania DPS.........  -, -, N
    Minke Whale...................  Balaenoptera           NA..................  -, -, N                     450
                                     acutorostrata.
    Sei Whale.....................  Balaenoptera borealis  NA..................  E, D, Y                     821
    Omura's Whale.................  Balaenoptera omurai..  NA..................  -, -, N                     160
----------------------------------------------------------------------------------------------------------------
                              Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm Whale...................  Physeter               NA..................  E, D, Y                   5,146
                                     macrocephalus.
Family Kogiidae:
    Dwarf Sperm Whale.............  Kogia sima...........  NA..................  -, -, N                  27,395
    Pygmy Sperm Whale.............  Kogia breviceps......  NA..................  -, -, N                  11,168
Family Ziphiidae (beaked whales):
    Blainville's Beaked Whale.....  Mesoplodon             NA..................  -, -, N                   3,376
                                     densirostris.
    Cuvier's Beaked Whale.........  Ziphius cavirostris..  NA..................  -, -, N                   2,642
    Longman's Beaked Whale........  Indopacetus pacificus  NA..................  -, -, N                  11,253
    Ginko-Toothed Beaked Whale....  Mesoplodon ginkgodens  NA..................  -, -, N                   7,567
    Deraniyagala's Beaked Whale...  Mesoplodon hotaula...  NA..................  -, -, N                      NA
Family Delphinidae:
    False Killer Whale............  Pseudorca crassidens.  NA..................  -, -, N                   4,218
    Killer Whale..................  Orcinus orca.........  NA..................  -, -, N                     253
    Melon-Headed Whale............  Peponocephala electra  NA..................  -, -, N                  16,551
    Pygmy Killer Whale............  Feresa attenuata.....  NA..................  -, -, N                     527
    Short-Finned Pilot Whale......  Globicephala           NA..................  -, -, N                   6,583
                                     macrorhynchus.
    Bottlenose Dolphin............  Tursiops truncatus...  NA..................  -, -, N                   1,076
    Fraser's Dolphin..............  Lagenodelphis hosei..  NA..................  -, -, N                  76,476
    Pantropical Spotted Dolphin...  Stenella attenuata...  NA..................  -, -, N                  85,755
    Risso's Dolphin...............  Grampus griseus......  NA..................  -, -, N                  17,184
    Rough-Toothed Dolphin.........  Steno bredanensis....  NA..................  -, -, N                   1,815
    Spinner Dolphin...............  Stenella longirostris  NA..................  -, -, N                   5,232
    Striped Dolphin...............  Stenella coeruleoalba  NA..................  -, -, N                  24,528
----------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/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\ Abundance estimates for marine mammals in the survey location were calculated using density data for marine
  mammals from the U.S. Navy Marine Species Density Database Phase III for the Mariana Islands Training and
  Testing Study Area report (DoN 2018).

    As indicated above, all 27 species in table 1 temporally and 
spatially co-occur with the activity to the degree that take is 
reasonably likely to occur. All species that could potentially occur in 
the planned survey areas are included in table 3 of the IHA 
application.
    A detailed description of the of the species likely to be affected 
by the geophysical survey, including brief introductions to the species 
and relevant stocks as well as available information regarding 
population trends and threats, and information regarding local 
occurrence, were provided in the Federal Register notice for the 
proposed IHA (89 FR 81429, October 8, 2024). Since that time, we are 
not aware of any changes in the status of these species; therefore, 
detailed descriptions are not provided here. Please refer to that 
Federal Register notice for these descriptions. Please also refer to 
NMFS' website (https://www.fisheries.noaa.gov/find-species) for 
generalized species accounts.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and 
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al., 
(2007, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). On October 24, 2024, NMFS published 
(89 FR 84872) the final Updated Technical Guidance, which includes 
updated thresholds and

[[Page 101558]]

weighting functions to inform auditory injury estimates, and has 
replaced the 2018 Technical Guidance used previously (NMFS 2018). The 
updated hearing groups are presented below (table 2). The references, 
analysis, and methodology used in the development of the hearing groups 
are described in NMFS' 2024 Technical Guidance, which may be accessed 
at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                  Table 2--Marine Mammal Hearing Groups
                              [NMFS, 2024]
------------------------------------------------------------------------
         Hearing group [supcaret]            Generalized hearing range *
------------------------------------------------------------------------
UNDERWATER:...............................
    Low-frequency (LF) cetaceans (baleen    7 Hz to 36 * kHz.
     whales) +.
    High-frequency (HF) cetaceans           150 Hz to 160 kHz.
     (dolphins, toothed whales, beaked
     whales, bottlenose whales).
    Very High-frequency (VHF) cetaceans     200 Hz to 165 kHz.
     (true porpoises, Kogia, river
     dolphins, Cephalorhynchid,
     Lagenorhynchus cruciger & L.
     australis).
    Phocid pinnipeds (PW) (underwater)      40 Hz to 90 kHz.
     (true seals).
    Otariid pinnipeds (OW) (underwater)     60 Hz to 68 kHz.
     (sea lions and fur seals).
------------------------------------------------------------------------
[supcaret] Southall et al., 2019 indicates that as more data become
  available there may be separate hearing group designations for Very
  Low-Frequency cetaceans (blue, fin, right, and bowhead whales) and Mid-
  Frequency cetaceans (sperm, killer, and beaked whales). However, at
  this point, all baleen whales are part of the LF cetacean hearing
  group, and sperm, killer, and beaked whales are part of the HF
  cetacean hearing group. Additionally, recent data indicates that as
  more data become available for Monachinae seals, separate hearing
  group designations may be appropriate for the two phocid subfamilies
  (Ruscher et al., 2021; Sills et al., 2021).
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges may not be as broad. Generalized hearing range
  chosen based on ~65 dB threshold from composite audiogram, previous
  analysis in NMFS 2018, and/or data from Southall et al., 2007;
  Southall et al., 2019. Additionally, animals are able to detect very
  loud sounds above and below that ``generalized'' hearing range.
+ NMFS is aware that the National Marine Mammal Foundation successfully
  collected preliminary hearing data on two minke whales during their
  third field season (2023) in Norway. These data have implications for
  not only the generalized hearing range for low-frequency cetaceans but
  also on their weighting function. However, at this time, no official
  results have been published. Furthermore, a fourth field season (2024)
  is proposed, where more data will likely be collected. Thus, it is
  premature for us to propose any changes to our current Updated
  Technical Guidance. However, mysticete hearing data is identified as a
  special circumstance that could merit re-evaluating the acoustic
  criteria in this document. Therefore, we anticipate that once the data
  from both field seasons are published, it will likely necessitate
  updating this document (i.e., likely after the data gathered in the
  summer 2024 field season and associated analysis are published).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat
    The effects of underwater noise from SIO's survey activities have 
the potential to result in behavioral harassment of marine mammals in 
the vicinity of the survey area. The notice of proposed IHA (89 FR 
81429, October 8, 2024) included a discussion of the effects of 
anthropogenic noise on marine mammals and the potential effects of 
underwater noise from SIO on marine mammals and their habitat. That 
information and analysis is incorporated by reference into this final 
IHA determination and is not repeated here; please refer to the notice 
of proposed IHA (89 FR 81429, October 8, 2024).
Estimated Take of Marine Mammals
    This section provides an estimate of the number of incidental takes 
authorized through the IHA, which will inform NMFS' consideration of 
``small numbers,'' the negligible impact determinations, and impacts on 
subsistence uses.
    Harassment is the only type of take expected to result from these 
activities. 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).
    Authorized takes will be by Level B harassment only, in the form of 
behavioral reactions and/or temporary threshold shift (TTS) for 
individual marine mammals resulting from exposure to noise from the use 
of seismic airguns. Based on the nature of the activity and the 
anticipated effectiveness of the mitigation measures (i.e., shutdown) 
discussed in detail below in the Mitigation section, Level A harassment 
is neither anticipated nor authorized. As described previously, no 
serious injury or mortality is anticipated or authorized for this 
activity. Below, we describe how the authorized take numbers are 
estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic thresholds above which NMFS believes the best 
available science indicates marine mammals will likely be behaviorally 
harassed or incur some degree of permanent hearing impairment; (2) the 
area or volume of water that will be ensonified above these levels in a 
day; (3) the density or occurrence of marine mammals within these 
ensonified areas; and, (4) the number of days of activities. We note 
that while these factors can contribute to a basic calculation to 
provide an initial prediction of potential takes, additional 
information that can qualitatively inform take estimates is also 
sometimes available (e.g., previous monitoring results or average group 
size). Below, we describe the factors considered here in more detail 
and present the take estimates.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur auditory injury of some degree (equated 
to Level A harassment).
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area,

[[Page 101559]]

predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 decibel (dB) 
(referenced to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., 
vibratory pile driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa 
for non-explosive impulsive (e.g., seismic airguns) or intermittent 
(e.g., scientific sonar) sources. Generally speaking, Level B 
harassment take estimates based on these behavioral harassment 
thresholds are expected to include any likely takes by TTS as, in most 
cases, the likelihood of TTS occurs at distances from the source less 
than those at which behavioral harassment is likely. TTS of a 
sufficient degree can manifest as behavioral harassment, as reduced 
hearing sensitivity and the potential reduced opportunities to detect 
important signals (conspecific communication, predators, prey) may 
result in changes in behavior patterns that would not otherwise occur.
    SIO's planned activity includes the use of impulsive seismic 
sources (i.e., airguns), and therefore the 160 dB re 1 [mu]Pa is 
applicable.
    Level A harassment--NMFS' Updated Technical Guidance for Assessing 
the Effects of Anthropogenic Sound on Marine Mammal Hearing (NMFS, 2024 
(2024 Updated Technical Guidance)) identifies dual criteria to assess 
auditory injury (Level A harassment) to five different marine mammal 
groups (based on hearing sensitivity) as a result of exposure to noise 
from two different types of sources (impulsive or non-impulsive). NMFS 
defines auditory injury as ``damage to the inner ear that can result in 
destruction of tissue . . . which may or may not result in permanent 
threshold shift (PTS)'' (NMFS, 2024). NMFS defines PTS as a permanent, 
irreversible increase in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2024). PTS does not 
generally affect more than a limited frequency range, and an animal 
that has incurred PTS has incurred some level of hearing loss at the 
relevant frequencies; typically, animals with PTS are not functionally 
deaf (Au and Hastings, 2008; Finneran, 2016).
    These thresholds are provided in the tables below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2024 Updated Technical Guidance, which may be 
accessed at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
    SIO's planned activity includes the use of impulsive seismic 
sources (i.e., airguns).

                Table 3--NMFS' 2024 Thresholds Identifying the Onset of Auditory Injury (AUD INJ)
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds * (received level)
             Hearing group             -------------------------------------------------------------------------
                                                Impulsive                          Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans..........  Cell 1: Lp, 0-pk,flat:     Cell 2: LE,  LF,24h: 197 dB.
                                         222 dB; LE,  LF,24h: 183
                                         dB.
High-Frequency (HF) Cetaceans.........  Cell 3: Lp, 0-pk,flat:     Cell 4: LE,  HF,24h: 201 dB.
                                         230 dB; LE,HF,24h: 193
                                         dB.
Very High-Frequency (VHF) Cetaceans...  Cell 5: Lpk, 0-pk, flat:   Cell 6: LE, p,VHF, 24h: 181 dB.
                                         202 dB; LE, p, VHF,24h:
                                         159 dB.
Phocid Pinnipeds (PW) (Underwater)....  Cell 7: Lp 0-pk,flat: 223  Cell 8: LE, p, PW,24h: 195 dB.
                                         dB; LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)...  Cell 9: Lp 0-pk,flat: 230  Cell 10: LE, p, OW,24h: 199 dB.
                                         dB; LE, p, OW,24h: 185
                                         dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
  calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
  level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
  impulsive sources.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa (underwater) and 20 [micro]Pa (in
  air), and weighted cumulative sound exposure level (LE,p) has a reference value of 1 [micro]Pa2s (underwater)
  and 20 [micro]Pa2s (in air). In this table, criteria are abbreviated to be more reflective of International
  Organization for Standardization standards (ISO 2017; ISO 2020). The subscript ``flat'' is being included to
  indicate peak sound pressure are flat weighted or unweighted within the generalized hearing range of marine
  mammals underwater (i.e., 7 Hz to 165 kHz) or in air (i.e., 42 Hz to 52 kHz). The subscript associated with
  cumulative sound exposure level criteria indicates the designated marine mammal auditory weighting function
  (LF, HF, and VHF cetaceans, and PW, OW, PA, and OA pinnipeds) and that the recommended accumulation period is
  24 hours. The weighted cumulative sound exposure level criteria could be exceeded in a multitude of ways
  (i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for action proponents
  to indicate the conditions under which these criteria will be exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    When the Technical Guidance was published (NMFS, 2016), in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a user spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or occurrence to help predict takes. We note that 
because of some of the assumptions included in the methods used for 
these tools, we anticipate that isopleths produced are typically going 
to be overestimates of some degree, which may result in some degree of 
overestimation of Level A harassment take. However, these tools offer 
the best way to predict appropriate isopleths when more sophisticated 
3-D modeling methods are not available, and NMFS continues to develop 
ways to quantitatively refine these tools and will qualitatively 
address the output where appropriate.
    The planned survey will entail the use of a 4-airgun array with a 
total discharge volume of 420 in\3\ at a tow depth of 3 m. SIO used 
modeling by the L-DEO, which determines the 160 dBrms radius 
for the airgun source down to a maximum depth of 2,000 m. Received 
sound levels have been predicted by L-DEO's model (Diebold et al., 
2010) as a function of distance from the 4-airgun array. This modeling 
approach uses ray tracing for the direct wave traveling

[[Page 101560]]

from the array to the receiver and its associated source ghost 
(reflection at the air-water interface in the vicinity of the array), 
in a constant-velocity half-space (infinite homogeneous ocean layer, 
unbounded by a seafloor). In addition, propagation measurements of 
pulses from the 36-airgun array at a tow depth of 6 m have been 
reported in deep water (~1,600 m), intermediate water depth on the 
slope (~600-1,100 m), and shallow water (~50 m) in the Gulf of Mexico 
(Tolstoy et al., 2009; Diebold et al., 2010).
    For deep and intermediate water cases, the field measurements 
cannot be used readily to derive the harassment isopleths, as at those 
sites the calibration hydrophone was located at a roughly constant 
depth of 350-550 m, which may not intersect all the SPL isopleths at 
their widest point from the sea surface down to the assumed maximum 
relevant water depth (~2,000 m) for marine mammals. At short ranges, 
where the direct arrivals dominate and the effects of seafloor 
interactions are minimal, the data at the deep sites are suitable for 
comparison with modeled levels at the depth of the calibration 
hydrophone. At longer ranges, the comparison with the model--
constructed from the maximum SPL through the entire water column at 
varying distances from the airgun array--is the most relevant.
    In deep and intermediate water depths at short ranges, sound levels 
for direct arrivals recorded by the calibration hydrophone and L-DEO 
model results for the same array tow depth are in good alignment (see 
figures 12 and 14 in Diebold et al., 2010). Consequently, isopleths 
falling within this domain can be predicted reliably by the L-DEO 
model, although they may be imperfectly sampled by measurements 
recorded at a single depth. At greater distances, the calibration data 
show that seafloor-reflected and sub-seafloor-refracted arrivals 
dominate, whereas the direct arrivals become weak and/or incoherent 
(see figures 11, 12, and 16 in Diebold et al., 2010). Aside from local 
topography effects, the region around the critical distance is where 
the observed levels rise closest to the model curve. However, the 
observed sound levels are found to fall almost entirely below the model 
curve. Thus, analysis of the Gulf of Mexico calibration measurements 
demonstrates that although simple, the L-DEO model is a robust tool for 
conservatively estimating isopleths.
    The planned low-energy survey will acquire data with the 4-airgun 
array at a tow depth of 3 m. For deep water (>1,000 m), we use the 
deep-water radii obtained from L-DEO model results down to a maximum 
water depth of 2,000 m for the airgun array.
    L-DEO's modeling methodology is described in greater detail in 
SIO's application. The estimated distances to the Level B harassment 
isopleth for the planned airgun configuration are shown in table 4.

  Table 4--Predicted Radial Distances From the R/V Sikuliaq Seismic Source to Isopleth Corresponding to Level B
                                              Harassment Threshold
----------------------------------------------------------------------------------------------------------------
                                                                                                    Predicted
                                                                                                  distances (in
                     Airgun configuration                       Tow depth (m)   Water depth (m)  m) to the Level
                                                                                                   B harassment
                                                                                                    threshold
----------------------------------------------------------------------------------------------------------------
4 105-in\3\ airguns..........................................               3           >1,000            1,408
----------------------------------------------------------------------------------------------------------------


          Table 5--Modeled Radial Distance to Isopleths Corresponding to Level A Harassment Thresholds
                                                   [NMFS 2024]
----------------------------------------------------------------------------------------------------------------
                                                                                                     Very high
                                                                   Low frequency  High frequency     frequency
                                                                     cetaceans       cetaceans       cetaceans
----------------------------------------------------------------------------------------------------------------
AUD INJ SELcum..................................................            50.6               0               0
AUD INJ Peak....................................................            8.44            NA/0              88
----------------------------------------------------------------------------------------------------------------
The largest distance (in bold) of the dual criteria (SEL cum or Peak) was used to estimate threshold distances
  and potential takes by Level A harassment.
NA not applicable or available and assumed to be 0.

    Table 5 presents the modeled auditory injury isopleths for each 
cetacean hearing group based on L-DEO modeling incorporated in the 
companion user spreadsheet, for the low-energy surveys with the 
shortest shot interval (i.e., greatest potential to cause auditory 
injury based on accumulated sound energy) (NMFS 2024).
    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal hearing groups, were calculated based on 
modeling performed by L-DEO using the Nucleus software program and the 
NMFS user spreadsheet, described below. The acoustic thresholds for 
impulsive sounds contained in the NMFS Technical Guidance were 
presented as dual metric acoustic thresholds using both cumulative SEL 
(SELcum) and peak sound pressure metrics (NMFS, 2024). As 
dual metrics, NMFS considers onset of auditory injury (Level A 
harassment) to have occurred when either one of the two metrics is 
exceeded (i.e., metric resulting in the largest isopleth). The 
SELcum metric considers both level and duration of exposure, 
as well as auditory weighting functions by marine mammal hearing group.
    The SELcum for the 4-airgun array is derived from 
calculating the modified farfield signature. The farfield signature is 
often used as a theoretical representation of the source level. To 
compute the farfield signature, the source level is estimated at a 
large distance (right) below the array (e.g., 9 km), and this level is 
back projected mathematically to a notional distance of 1 m from the 
array's geometrical center. However, it has been recognized that the 
source level from the theoretical farfield signature is never 
physically achieved at the source when the source is an array of 
multiple airguns separated in space (Tolstoy et al., 2009). Near the 
source (at short ranges, distances <1 km), the pulses of sound pressure 
from each

[[Page 101561]]

individual airgun in the source array do not stack constructively as 
they do for the theoretical farfield signature. The pulses from the 
different airguns spread out in time such that the source levels 
observed or modeled are the result of the summation of pulses from a 
few airguns, not the full array (Tolstoy et al., 2009). At larger 
distances, away from the source array center, sound pressure of all the 
airguns in the array stack coherently, but not within one time sample, 
resulting in smaller source levels (a few dB) than the source level 
derived from the farfield signature. Because the farfield signature 
does not take into account the large array effect near the source and 
is calculated as a point source, the farfield signature is not an 
appropriate measure of the sound source level for large arrays. See 
SIO's application for further detail on acoustic modeling.
    Auditory injury is unlikely to occur for high-frequency cetaceans, 
given the very small modeled zones of injury for those species (all 
estimated zones are less than 1 m for high-frequency cetaceans), in 
context of distributed source dynamics.
    In consideration of the received sound levels in the near-field as 
described above, we expect the potential for Level A harassment of 
high-frequency cetaceans to be de minimis, even before the likely 
moderating effects of aversion and/or other compensatory behaviors 
(e.g., Nachtigall et al., 2018) are considered. We do not anticipate 
that Level A harassment is a likely outcome for any high-frequency 
cetacean and do not authorize any take by Level A harassment for these 
species.
    The Level A and Level B harassment estimates are based on a 
consideration of the number of marine mammals that could be within the 
area around the operating airgun array where received levels of sound 
>=160 dB re 1 [micro]Pa rms are predicted to occur. The estimated 
numbers are based on the densities (numbers per unit area) of marine 
mammals expected to occur in the area in the absence of seismic 
surveys. To the extent that marine mammals tend to move away from 
seismic sources before the sound level reaches the criterion level and 
tend not to approach an operating airgun array, these estimates likely 
overestimate the numbers actually exposed to the specified level of 
sound.

Marine Mammal Occurrence

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information which 
will inform the take calculations.
    For the planned survey area, SIO used density data from the U.S. 
Navy's Marine Species Density Database Phase III for the Mariana 
Islands Training and Testing (MITT) Study Area (DoN, 2018). The U.S. 
Navy modeled densities for two areas within the MITT: the Mariana 
Islands Training and Testing Representative Study Area, ~580 km to the 
west of the planned survey area, and the Transit Corridor 
Representative Study Area surrounding Wake Island, ~120 km to the east 
of the planned survey area (DoN, 2018). The planned survey area lies 
between the two MITT modeled areas and does not overlap either area. As 
the planned tracklines are located closer to Wake Island than the 
Mariana Islands, the MITT seasonal density estimates for the Transit 
Corridor Representative Study Area were used here. As the survey is 
planned for December 2024 to January 2025, the densities for winter 
(December through February) were used to calculate takes for marine 
mammals. No densities were available for Deraniyagala's beaked whale. 
However, the density for ginkgo-toothed beaked whale was applied to 
Deraniyagala's beaked whale and ginkgo-toothed beaked whale as a 
combined group, as these two species are difficult to distinguish.

Take Estimation

    Here, we describe how the information provided above is synthesized 
to produce a quantitative estimate of the take that is reasonably 
likely to occur and authorized. In order to estimate the number of 
marine mammals predicted to be exposed to sound levels that would 
result in Level A or Level B harassment, radial distances from the 
airgun array to the predicted isopleth corresponding to the Level A 
harassment and Level B harassment thresholds are calculated, as 
described above. Those radial distances were then used to calculate the 
area(s) around the airgun array predicted to be ensonified to sound 
levels that exceed the harassment thresholds. The distance for the 160-
dB Level B harassment threshold and auditory injury (Level A 
harassment) thresholds (based on L-DEO model results) was used to draw 
a buffer around the area expected to be ensonified (i.e., the survey 
area). The ensonified areas were then increased by 25 percent to 
account for potential delays, which is equivalent to adding 25 percent 
to the planned line km to be surveyed. The density for each species was 
then multiplied by the daily ensonified areas (increased as described 
above) and then multiplied by the number of survey days (14) to 
estimate potential takes (see appendix B of SIO's application for more 
information).
    SIO assumed that their estimates of marine mammal exposures above 
harassment thresholds equate to take and requested authorization of 
those takes. Those estimates in turn form the basis for our take 
authorization numbers. Based on the nature of the activity and the 
anticipated effectiveness of the mitigation measures (i.e., shutdown) 
discussed in detail below in the Mitigation section, Level A harassment 
is neither anticipated nor authorized. Therefore we have added SIO's 
estimated exposures above Level A harassment thresholds to their 
estimated exposures above the Level B harassment threshold to produce a 
total number of incidents of take by Level B harassment that are 
authorized. Estimated exposures and authorized take numbers are shown 
in table 6.

                                                                Table 6--Authorized Take
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Estimated take              Authorized take
                                                          --------------------------------------        \1\                                Percent of
                       Common name                                                              -------------------     Abundance          abundance
                                                                Level B            Level A            Level B
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue Whale...............................................                  1                  0                  1                150               0.67
Bryde's Whale............................................                  3                  0                  3              1,596               0.19
Fin Whale................................................                  1                  0                  1                 46               2.17
Humpback Whale \2\.......................................                 10                  0                 10              2,673               0.37
Minke Whale..............................................                  2                  0                  2                450               0.44
Sei Whale................................................                  1                  0              \3\ 2                821               0.24
Omura's Whale............................................                  0                  0              \3\ 1                160               0.63
Sperm Whale..............................................                 25                  0                 25              5,146               0.49
Dwarf Sperm Whale........................................                 45                  3                 48             27,395               0.18
Pygmy Sperm Whale........................................                 18                  1                 19             11,168               0.17

[[Page 101562]]

 
Blainville's Beaked Whale................................                  8                  0                  8              3,376               0.24
Cuvier's Beaked Whale....................................                 41                  0                 41              2,642               1.56
Longman's Beaked Whale...................................                  3                  0                  3             11,253               0.03
Ginko-Toothed Beaked Whale...............................                 21                  0                 21              7,567               0.28
Deraniyagala's Beaked Whale..............................
False Killer Whale.......................................                  6                  0             \3\ 10              4,218               0.24
Killer Whale.............................................                  1                  0              \3\ 5                253               1.98
Melon-Headed Whale.......................................                 30                  0             \3\ 95             16,551               0.57
Pygmy Killer Whale.......................................                  1                  0              \3\ 6                527               1.14
Short-Finned Pilot Whale.................................                 23                  0                 23              6,583               0.35
Bottlenose Dolphin.......................................                  9                  0                  9              1,076               0.84
Fraser's Dolphin.........................................                 28                  0                 28             76,476               0.04
Pantropical Spotted Dolphin..............................                125                  0                125             85,755               0.15
Risso's Dolphin..........................................                  5                  0                 27             17,184               0.16
Rough-Toothed Dolphin....................................                 20                  0                 20              1,815               1.10
Spinner Dolphin..........................................                 21                  0             \3\ 98              5,232               1.87
Striped Dolphin..........................................                 65                  0                 65             24,528               0.27
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Authorized take is Level A plus Level B calculated takes.
\2\ All takes are assumed to be from the Western North Pacific DPS.
\3\ Takes have been increased to mean group size for the Mariana Islands based on Fulling et al., (2011) where available or for Hawaii (e.g., Risso's
  dolphin and killer whale) as reported by Bradford et al., (2017), or Jefferson et al., (2015).

Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
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 the 
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)).
    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, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, and impact on 
operations.

Vessel-Based Visual Mitigation Monitoring

    Visual monitoring requires the use of trained observers (herein 
referred to as visual protected species observers (PSO)) to scan the 
ocean surface for the presence of marine mammals. The area to be 
scanned visually includes primarily the shutdown zone (SZ), within 
which observation of certain marine mammals requires shutdown of the 
acoustic source, a buffer zone, and to the extent possible depending on 
conditions, the surrounding waters. The buffer zone means an area 
beyond the SZ to be monitored for the presence of marine mammals that 
may enter the SZ. During pre-start clearance monitoring (i.e., before 
ramp-up begins), the buffer zone also acts as an extension of the SZ in 
that observations of marine mammals within the buffer zone will also 
prevent airgun operations from beginning (i.e., ramp-up). The buffer 
zone encompasses the area at and below the sea surface from the edge of 
the 0-100 m SZ, out to a radius of 200 m from the edges of the airgun 
array (100-200 m). This 200-m zone (SZ plus buffer) represents the pre-
start clearance zone. Visual monitoring of the SZ and adjacent waters 
(buffer plus surrounding waters) is intended to establish and, when 
visual conditions allow, maintain zones around the sound source that 
are clear of marine mammals, thereby reducing or eliminating the 
potential for injury and minimizing the potential for more severe 
behavioral reactions for animals occurring closer to the vessel. Visual 
monitoring of the buffer zone is intended to (1) provide additional 
protection to marine mammals that may be in the vicinity of the vessel 
during pre-start clearance, and (2) during airgun use, aid in 
establishing and maintaining the SZ by alerting the visual observer and 
crew of marine mammals that are outside of, but may approach and enter, 
the SZ.
    During survey operations (e.g., any day on which use of the airgun 
array is planned to occur and whenever the airgun array is in the 
water, whether activated or not), a minimum of two visual PSOs must be 
on duty and conducting visual observations at all times during daylight 
hours (i.e., from 30 minutes prior to sunrise through 30 minutes 
following sunset). Visual monitoring of the pre-start clearance zone 
must begin no less than 30 minutes prior to ramp-up and monitoring must 
continue until 1 hour after use of the airgun array ceases or until 30 
minutes past sunset. Visual PSOs shall coordinate to ensure 360[deg] 
visual coverage around the vessel from the most appropriate observation 
posts and shall conduct visual observations using binoculars and the 
naked eye while free from distractions and in a consistent, systematic, 
and diligent manner.
    PSOs shall establish and monitor the SZ and buffer zone. These 
zones shall

[[Page 101563]]

be based upon the radial distance from the edges of the airgun array 
(rather than being based on the center of the array or around the 
vessel itself). During use of the airgun array (i.e., anytime airguns 
are active, including ramp-up), detections of marine mammals within the 
buffer zone (but outside the SZ) shall be communicated to the operator 
to prepare for the potential shutdown of the airgun array. Any 
observations of marine mammals by crew members shall be relayed to the 
PSO team. During good conditions (e.g., daylight hours; Beaufort sea 
state (BSS) 3 or less), visual PSOs shall conduct observations when the 
airgun array is not operating for comparison of sighting rates and 
behavior with and without use of the airgun array and between 
acquisition periods, to the maximum extent practicable.
    Visual PSOs may be on watch for a maximum of 4 consecutive hours 
followed by a break of at least 1 hour between watches and may conduct 
a maximum of 12 hours of observation per 24-hour period. Observational 
duties may not exceed 12 hours per 24-hour period for any individual 
PSO.

Establishment of Shutdown and Pre-Start Clearance Zones

    A SZ is a defined area within which occurrence of a marine mammal 
triggers mitigation action intended to reduce the potential for certain 
outcomes (e.g., auditory injury, disruption of critical behaviors). The 
PSOs will establish a minimum SZ with a 100-m radius. The 100-m SZ will 
be based on radial distance from the edge of the airgun array (rather 
than being based on the center of the array or around the vessel 
itself). With certain exceptions (described below), if a marine mammal 
appears within or enters this zone, the airgun array will be shut down.
    The pre-start clearance zone is defined as the area that must be 
clear of marine mammals prior to beginning ramp-up of the airgun array 
and includes the SZ plus the buffer zone. Detections of marine mammals 
within the pre-start clearance zone will prevent airgun operations from 
beginning (i.e., ramp-up).
    The 100-m SZ is intended to be precautionary in the sense that it 
will be expected to contain sound exceeding the injury criteria for all 
cetacean hearing groups, (based on the dual criteria of 
SELcum and peak SPL), while also providing a consistent, 
reasonably observable zone within which PSOs will typically be able to 
conduct effective observational effort. Additionally, a 100-m SZ is 
expected to minimize the likelihood that marine mammals will be exposed 
to levels likely to result in more severe behavioral responses. 
Although significantly greater distances may be observed from an 
elevated platform under good conditions, we expect that 100 m is likely 
regularly attainable for PSOs using the naked eye during typical 
conditions. The pre-start clearance zone simply represents the addition 
of a buffer to the SZ, doubling the SZ size during pre-clearance.
    An extended SZ of 500 m must be implemented for all beaked whales, 
a large whale with a calf, and groups of six or more large whales. No 
buffer of this extended SZ is required, as NMFS concludes that this 
extended SZ is sufficiently protective to mitigate harassment to these 
groups.

Pre-Start Clearance and Ramp-Up

    Ramp-up (sometimes referred to as ``soft start'') means the gradual 
and systematic increase of emitted sound levels from an airgun array. 
The intent of pre-start clearance observation (30 minutes) is to ensure 
no marine mammals are observed within the pre-start clearance zone (or 
extended SZ, for beaked whales, a large whale with a calf, and groups 
of six or more large whales) prior to the beginning of ramp-up. During 
the pre-start clearance period is the only time observations of marine 
mammals in the buffer zone would prevent operations (i.e., the 
beginning of ramp-up). The intent of the ramp-up is to warn marine 
mammals of pending seismic survey operations and to allow sufficient 
time for those animals to leave the immediate vicinity prior to the 
sound source reaching full intensity. A ramp-up procedure, involving a 
stepwise increase in the number of airguns firing and total array 
volume until all operational airguns are activated and the full volume 
is achieved, is required at all times as part of the activation of the 
airgun array. All operators must adhere to the following pre-start 
clearance and ramp-up requirements:
     The operator must notify a designated PSO of the planned 
start of ramp-up as agreed upon with the lead PSO; the notification 
time should not be less than 60 minutes prior to the planned ramp-up in 
order to allow the PSOs time to monitor the pre-start clearance zone 
(and extended SZ) for 30 minutes prior to the initiation of ramp-up 
(pre-start clearance);
     Ramp-ups shall be scheduled so as to minimize the time 
spent with the source activated prior to reaching the designated run-
in;
     One of the PSOs conducting pre-start clearance 
observations must be notified again immediately prior to initiating 
ramp-up procedures and the operator must receive confirmation from the 
PSO to proceed;
     Ramp-up may not be initiated if any marine mammal is 
within the applicable shutdown or buffer zone. If a marine mammal is 
observed within the pre-start clearance zone (or extended SZ, for 
beaked whales, a large whale with a calf, and groups of six or more 
large whales) during the 30 minute pre-start clearance period, ramp-up 
may not begin until the animal(s) has been observed exiting the zones 
or until an additional time period has elapsed with no further 
sightings (15 minutes for small odontocetes, and 30 minutes for all 
mysticetes and all other odontocetes, including sperm whales, beaked 
whales, and large delphinids, such as pilot whales);
     Ramp-up must begin by activating one GI airgun and shall 
continue in stages, doubling the number of active elements at the 
commencement of each stage, with each stage lasting no less than five 
minutes. The operator must provide information to the PSO documenting 
that appropriate procedures were followed;
     PSOs must monitor the pre-start clearance zone and 
extended SZ during ramp-up, and ramp-up must cease and the source must 
be shut down upon detection of a marine mammal within the applicable 
zone. Once ramp-up has begun, detections of marine mammals within the 
buffer zone do not require shutdown, but such observation shall be 
communicated to the operator to prepare for the potential shutdown;
     Ramp-up may occur at times of poor visibility, including 
nighttime, if appropriate visual monitoring has occurred with no 
detections in the 30 minutes prior to beginning ramp-up. Airgun array 
activation may only occur at times of poor visibility where operational 
planning cannot reasonably avoid such circumstances;
     If the airgun array is shut down for brief periods (i.e., 
less than 30 minutes) for reasons other than implementation of 
prescribed mitigation (e.g., mechanical difficulty), it may be 
activated again without ramp-up if PSOs have maintained constant visual 
observation and no visual detections of marine mammals have occurred 
within the pre-start clearance zone (or extended SZ, where applicable). 
For any longer shutdown, pre-start clearance observation and ramp-up 
are required; and
     Testing of the airgun array involving all elements 
requires ramp-up. Testing limited to individual source elements or 
strings does not require

[[Page 101564]]

ramp-up but does require pre-start clearance of 30 minutes.

Shutdown

    The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array. Any PSO on 
duty will have the authority to call for shutdown of the airgun array 
if a marine mammal is detected within the applicable SZ. The operator 
must also establish and maintain clear lines of communication directly 
between PSOs on duty and crew controlling the airgun array to ensure 
that shutdown commands are conveyed swiftly while allowing PSOs to 
maintain watch. When the airgun array is active (i.e., anytime one or 
more airguns is active, including during ramp-up) and (1) a marine 
mammal appears within or enters the applicable SZ, the airgun array 
will be shut down. When shutdown is called for by a PSO, the airgun 
array will be immediately deactivated and any dispute resolved only 
following deactivation.
    Following a shutdown, airgun activity will not resume until the 
marine mammal has cleared the SZ. The animal will be considered to have 
cleared the SZ if it is visually observed to have departed the SZ 
(i.e., animal is not required to fully exit the buffer zone where 
applicable), or it has not been seen within the SZ for 15 minutes for 
small odontocetes or 30 minutes for all mysticetes and all other 
odontocetes, including sperm whales, beaked whales, and large 
delphinids, such as pilot whales.
    The shutdown requirement is waived for specific genera of small 
dolphins if an individual is detected within the SZ. The small dolphin 
group is intended to encompass those members of the Family Delphinidae 
most likely to voluntarily approach the source vessel for purposes of 
interacting with the vessel and/or airgun array (e.g., bow riding). 
This exception to the shutdown requirement applies solely to the 
specific genera of small dolphins (Lagenodelphis, Stenella, Steno, and 
Tursiops).
    We include this small dolphin exception because shutdown 
requirements for these species under all circumstances represent 
practicability concerns without likely commensurate benefits for the 
animals in question. Small dolphins are generally the most commonly 
observed marine mammals in the specific geographic region and would 
typically be the only marine mammals likely to intentionally approach 
the vessel. As described above, auditory injury is extremely unlikely 
to occur for high-frequency cetaceans (e.g., delphinids), as this group 
is relatively insensitive to sound produced at the predominant 
frequencies in an airgun pulse while also having a relatively high 
threshold for the onset of auditory injury (i.e., permanent threshold 
shift).
    A large body of anecdotal evidence indicates that small dolphins 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding with no apparent effect observed 
(e.g., Barkaszi et al., 2012; Barkaszi and Kelly, 2018). The potential 
for increased shutdowns resulting from such a measure would require the 
Sikuliaq to revisit the missed track line to reacquire data, resulting 
in an overall increase in the total sound energy input to the marine 
environment and an increase in the total duration over which the survey 
is active in a given area. Although other high-frequency hearing 
specialists (e.g., large delphinids) are no more likely to incur 
auditory injury than are small dolphins, they are much less likely to 
approach vessels. Therefore, retaining a shutdown requirement for large 
delphinids would not have similar impacts in terms of either 
practicability for the applicant or corollary increase in sound energy 
output and time on the water. We do anticipate some benefit for a 
shutdown requirement for large delphinids in that it simplifies 
somewhat the total range of decision-making for PSOs and may preclude 
any potential for physiological effects other than to the auditory 
system as well as some more severe behavioral reactions for any such 
animals in close proximity to the Sikuliaq.
    Visual PSOs shall use best professional judgment in making the 
decision to call for a shutdown if there is uncertainty regarding 
identification (i.e., whether the observed marine mammal(s) belongs to 
one of the delphinid genera for which shutdown is waived or one of the 
species with a larger SZ).
    SIO must implement shutdown if a marine mammal species for which 
take was not authorized or a species for which authorization was 
granted but the authorized takes have been met approaches the Level A 
or Level B harassment zones. SIO must also implement shutdown if any 
large whale (defined as a sperm whale or any mysticete species) with a 
calf (defined as an animal less than two-thirds the body size of an 
adult observed to be in close association with an adult) and/or an 
aggregation of six or more large whales are observed at any distance.

Vessel Strike Avoidance Mitigation Measures

    Vessel personnel should use an appropriate reference guide that 
includes identifying information on all marine mammals that may be 
encountered. Vessel operators must comply with the below measures 
except under extraordinary circumstances when the safety of the vessel 
or crew is in doubt or the safety of life at sea is in question. These 
requirements do not apply in any case where compliance would create an 
imminent and serious threat to a person or vessel or to the extent that 
a vessel is restricted in its ability to maneuver and, because of the 
restriction, cannot comply.
    Vessel operators and crews must maintain a vigilant watch for all 
marine mammals and slow down, stop their vessel, or alter course, as 
appropriate and regardless of vessel size, to avoid striking any marine 
mammal. A single marine mammal at the surface may indicate the presence 
of submerged animals in the vicinity of the vessel; therefore, 
precautionary measures should always be exercised. A visual observer 
aboard the vessel must monitor a vessel strike avoidance zone around 
the vessel (separation distances stated below). Visual observers 
monitoring the vessel strike avoidance zone may be third-party 
observers (i.e., PSOs) or crew members, but crew members responsible 
for these duties must be provided sufficient training to (1) 
distinguish marine mammals from other phenomena and (2) broadly to 
identify a marine mammal as a right whale, other whale (defined in this 
context as sperm whales or baleen whales other than right whales), or 
other marine mammals.
    Vessel speeds must be reduced to 10 knots (kn) (18.5 kn per hour) 
or less when mother/calf pairs, pods, or large assemblages of cetaceans 
are observed near a vessel. All vessels must maintain a minimum 
separation distance of 100 m from sperm whales and all other baleen 
whales. All vessels must, to the maximum extent practicable, attempt to 
maintain a minimum separation distance of 50 m from all other marine 
mammals, with an understanding that at times this may not be possible 
(e.g., for animals that approach the vessel).
    When marine mammals are sighted while a vessel is underway, the 
vessel shall take action as necessary to avoid violating the relevant 
separation distance (e.g., attempt to remain parallel to the animal's 
course, avoid excessive speed or abrupt changes in direction until the 
animal has left the area). If marine mammals are sighted within the

[[Page 101565]]

relevant separation distance, the vessel must reduce speed and shift 
the engine to neutral, not engaging the engines until animals are clear 
of the area. This does not apply to any vessel towing gear or any 
vessel that is navigationally constrained.
    Based on our evaluation of the applicant's planned measures, as 
well as other measures considered by NMFS, NMFS has determined that the 
mitigation measures provide the means of effecting the least 
practicable impact on the affected species or stocks and their habitat, 
paying particular attention to rookeries, mating grounds, and areas of 
similar significance.

Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Vessel-Based Visual Monitoring

    As described above, PSO observations will take place during daytime 
airgun operations. During seismic survey operations, at least five 
visual PSOs will be based aboard the Sikuliaq. Two visual PSOs will be 
on duty at all times during daytime hours. The operator will work with 
the selected third-party observer provider to ensure PSOs have all 
equipment (including backup equipment) needed to adequately perform 
necessary tasks, including accurate determination of distance and 
bearing to observed marine mammals. SIO must use dedicated, trained, 
and NMFS-approved PSOs. At least one visual PSO aboard the vessel must 
have a minimum of 90 days at-sea experience working in those roles, 
respectively, with no more than 18 months elapsed since the conclusion 
of the at-sea experience. One visual PSO with such experience shall be 
designated as the lead for the entire protected species observation 
team. The lead PSO shall serve as primary point of contact for the 
vessel operator and ensure all PSO requirements per the IHA are met. To 
the maximum extent practicable, the experienced PSOs should be 
scheduled to be on duty with those PSOs with appropriate training but 
who have not yet gained relevant experience. The PSOs must have no 
tasks other than to conduct observational effort, record observational 
data, and communicate with and instruct relevant vessel crew with 
regard to the presence of marine mammals and mitigation requirements. 
PSO resumes shall be provided to NMFS for approval. Monitoring shall be 
conducted in accordance with the following requirements:
     PSOs shall be independent, dedicated, trained visual PSOs 
and must be employed by a third-party observer provider;
     PSOs shall have no tasks other than to conduct 
observational effort, collect data, and communicate with and instruct 
relevant vessel crew with regard to the presence of protected species 
and mitigation requirements (including brief alerts regarding maritime 
hazards);
     PSOs shall have successfully completed an approved PSO 
training course appropriate for their designated task (visual);
     NMFS must review and approve PSO resumes accompanied by a 
relevant training course information packet that includes the name and 
qualifications (i.e., experience, training completed, or educational 
background) of the instructor(s), the course outline or syllabus, and 
course reference material as well as a document stating successful 
completion of the course;
     PSOs must successfully complete relevant training, 
including completion of all required coursework and passing (80 percent 
or greater) a written and/or oral examination developed for the 
training program;
     PSOs must have successfully attained a bachelor's degree 
from an accredited college or university with a major in one of the 
natural sciences, a minimum of 30 semester hours or equivalent in the 
biological sciences, and at least one undergraduate course in math or 
statistics;
     The educational requirements may be waived if the PSO has 
acquired the relevant skills through alternate experience. Requests for 
such a waiver shall be submitted to NMFS and must include written 
justification. Requests shall be granted or denied (with justification) 
by NMFS within 1 week of receipt of submitted information. Alternate 
experience that may be considered includes, but is not limited to (1) 
secondary education and/or experience comparable to PSO duties; (2) 
previous work experience conducting academic, commercial, or 
government-sponsored protected species surveys; or (3) previous work 
experience as a PSO; the PSO should demonstrate good standing and 
consistently good performance of PSO duties;
     For data collection purposes, PSOs shall use standardized 
electronic data collection forms. PSOs shall record detailed 
information about any implementation of mitigation requirements, 
including the distance of animals to the airgun array and description 
of specific actions that ensued, the behavior of the animal(s), any 
observed changes in behavior before and after implementation of 
mitigation, and if shutdown was implemented, the length of time before 
any subsequent ramp-up of the airgun array. If required mitigation was 
not implemented, PSOs should record a description of the circumstances. 
At a minimum, the following information must be recorded:
    [cir] Vessel name, vessel size and type, maximum speed capability 
of vessel;
    [cir] Dates (MM/DD/YYYY) of departures and returns to port with 
port name;

[[Page 101566]]

    [cir] PSO names and affiliations, PSO ID (initials or other 
identifier);
    [cir] Date (MM/DD/YYYY) and participants of PSO briefings;
    [cir] Visual monitoring equipment used (description);
    [cir] PSO location on vessel and height (meters) of observation 
location above water surface;
    [cir] Watch status (description);
    [cir] Dates (MM/DD/YYYY) and times (Greenwich Mean Time/UTC) of 
survey on/off effort and times (GMC/UTC) corresponding with PSO on/off 
effort;
    [cir] Vessel location (decimal degrees) when survey effort began 
and ended and vessel location at beginning and end of visual PSO duty 
shifts;
    [cir] Vessel location (decimal degrees) at 30-second intervals if 
obtainable from data collection software, otherwise at practical 
regular interval;
    [cir] Vessel heading (compass heading) and speed (kn) at beginning 
and end of visual PSO duty shifts and upon any change;
    [cir] Water depth (meters) (if obtainable from data collection 
software);
    [cir] Environmental conditions while on visual survey (at beginning 
and end of PSO shift and whenever conditions changed significantly), 
including BSS and any other relevant weather conditions including cloud 
cover, fog, sun glare, and overall visibility to the horizon;
    [cir] Factors that may have contributed to impaired observations 
during each PSO shift change or as needed as environmental conditions 
changed (description) (e.g., vessel traffic, equipment malfunctions); 
and
    [cir] Vessel/Survey activity information (and changes thereof) 
(description), such as airgun power output while in operation, number 
and volume of airguns operating in the array, tow depth of the array, 
and any other notes of significance (i.e., pre-start clearance, ramp-
up, shutdown, testing, shooting, ramp-up completion, end of operations, 
streamers, etc.); and
     Upon visual observation of any marine mammals, the 
following information must be recorded:
    [cir] Sighting ID (numeric);
    [cir] Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
    [cir] Location of PSO/observer (description);
    [cir] Vessel activity at the time of the sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other);
    [cir] PSO who sighted the animal/ID;
    [cir] Time/date of sighting (GMT/UTC, MM/DD/YYYY);
    [cir] Initial detection method (description);
    [cir] Sighting cue (description);
    [cir] Vessel location at time of sighting (decimal degrees);
    [cir] Water depth (meters);
    [cir] Direction of vessel's travel (compass direction);
    [cir] Speed (kn) of the vessel from which the observation was made;
    [cir] Direction of animal's travel relative to the vessel 
(description, compass heading);
    [cir] Bearing to sighting (degrees);
    [cir] Identification of the animal (e.g., genus/species, lowest 
possible taxonomic level, or unidentified) and the composition of the 
group if there is a mix of species;
    [cir] Species reliability (an indicator of confidence in 
identification) (1 = unsure/possible, 2 = probable, 3 = definite/sure, 
9 = unknown/not recorded);
    [cir] Estimated distance to the animal (meters) and method of 
estimating distance;
    [cir] Estimated number of animals (high/low/best) (numeric);
    [cir] Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
    [cir] Description (as many distinguishing features as possible of 
each individual seen, including length, shape, color, pattern, scars or 
markings, shape and size of dorsal fin, shape of head, and blow 
characteristics);
    [cir] Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding, 
traveling; as explicit and detailed as possible; note any observed 
changes in behavior);
    [cir] Animal's closest point of approach (meters) and/or closest 
distance from any element of the airgun array;
    [cir] Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up) and time and location of the 
action.
    [cir] Photos (Yes/No);
    [cir] Photo Frame Numbers (List of numbers); and
    [cir] Conditions at time of sighting (Visibility; Beaufort Sea 
State).

Reporting

    SIO shall submit a draft comprehensive report on all activities and 
monitoring results within 90 days of the completion of the survey or 
expiration of the IHA, whichever comes sooner. The report must describe 
all activities conducted and sightings of marine mammals, must provide 
full documentation of methods, results, and interpretation pertaining 
to all monitoring, and must summarize the dates and locations of survey 
operations and all marine mammal sightings (dates, times, locations, 
activities, associated survey activities). The draft report shall also 
include geo-referenced time-stamped vessel tracklines for all time 
periods during which airgun arrays were operating. Tracklines should 
include points recording any change in airgun array status (e.g., when 
the sources began operating, when they were turned off, or when they 
changed operational status such as from full array to single gun or 
vice versa). Geographic Information System files shall be provided in 
Environmental Systems Research Institute shapefile format and include 
the UTC date and time, latitude in decimal degrees, and longitude in 
decimal degrees. All coordinates shall be referenced to the WGS84 
geographic coordinate system. In addition to the report, all raw 
observational data shall be made available. The report must summarize 
data collected as described above in Monitoring and Reporting. A final 
report must be submitted within 30 days following resolution of any 
comments on the draft report.

Reporting Injured or Dead Marine Mammals

    Discovery of injured or dead marine mammals--In the event that 
personnel involved in the survey activities discover an injured or dead 
marine mammal, the SIO shall report the incident to the Office of 
Protected Resources (OPR) and NMFS as soon as feasible. The report must 
include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.
    Vessel strike--In the event of a strike of a marine mammal by any 
vessel involved in the activities covered by the authorization, SIO 
shall report the incident to OPR and NMFS as soon as feasible. The 
report must include the following information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Vessel's speed during and leading up to the incident;
     Vessel's course/heading and what operations were being 
conducted (if applicable);

[[Page 101567]]

     Status of all sound sources in use;
     Description of avoidance measures/requirements that were 
in place at the time of the strike and what additional measure were 
taken, if any, to avoid strike;
     Environmental conditions (e.g., wind speed and direction, 
BSS, cloud cover, visibility) immediately preceding the strike;
     Species identification (if known) or description of the 
animal(s) involved;
     Estimated size and length of the animal that was struck;
     Description of the behavior of the marine mammal 
immediately preceding and following the strike;
     If available, description of the presence and behavior of 
any other marine mammals present immediately preceding the strike;
     Estimated fate of the animal (e.g., dead, injured but 
alive, injured and moving, blood or tissue observed in the water, 
status unknown, disappeared); and
     To the extent practicable, photographs or video footage of 
the animal(s).

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis 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, or ambient noise levels).
    To avoid repetition, the discussion of our analysis applies to all 
the species listed in table 1, given that the anticipated effects of 
this activity on these different marine mammal stocks are expected to 
be similar, except where a species- or stock-specific discussion is 
warranted. NMFS does not anticipate that serious injury or mortality 
would occur as a result of SIO's planned survey, even in the absence of 
mitigation, and no serious injury or mortality is authorized. As 
discussed in the Potential Effects of Specified Activities on Marine 
Mammals and Their Habitat section above, non-auditory physical effects 
and vessel strike are not expected to occur. NMFS expects that all 
potential take would be in the form of Level B behavioral harassment in 
the form of temporary avoidance of the area or decreased foraging (if 
such activity was occurring), responses that are considered to be of 
low severity, and with no lasting biological consequences (e.g., 
Southall et al., 2007, 2021). These low-level impacts of behavioral 
harassment are not likely to impact the overall fitness of any 
individual or lead to population level effects of any species. As 
described above, Level A harassment is not expected to occur given the 
estimated small size of the Level A harassment zones.
    In addition, the maximum expected Level B harassment zone around 
the survey vessel is 1,408 m. Therefore, the ensonified area 
surrounding the vessel is relatively small compared to the overall 
distribution of animals in the area and their use of the habitat. 
Feeding behavior is not likely to be significantly impacted as prey 
species are mobile and are broadly distributed throughout the survey 
area; therefore, marine mammals that may be temporarily displaced 
during survey activities are expected to be able to resume foraging 
once they have moved away from areas with disturbing levels of 
underwater noise. Because of the short duration (14 survey days) and 
temporary nature of the disturbance and the availability of similar 
habitat and resources in the surrounding area, the impacts to marine 
mammals and marine mammal prey species are not expected to cause 
significant or long-term fitness consequences for individual marine 
mammals or their populations.
    Additionally, the acoustic ``footprint'' of the planned survey will 
be very small relative to the ranges of all marine mammals that would 
potentially be affected. Sound levels will increase in the marine 
environment in a relatively small area surrounding the vessel compared 
to the range of the marine mammals within the planned survey area. The 
seismic array will be active 24 hours per day throughout the duration 
of the survey. However, the very brief overall duration of the planned 
survey (14 survey days) will further limit potential impacts that may 
occur as a result of the planned activity.
    Of the marine mammal species that are likely to occur in the 
project area, the following species are listed as endangered under the 
ESA: humpback whales (Western North Pacific DPS), blue whales, fin 
whales, sei whales, and sperm whales. The take numbers authorized for 
these species (table 6) are minimal relative to their modeled 
population sizes; therefore, we do not expect population-level impacts 
to any of these species. Moreover, the actual range of the populations 
extends past the area covered by the model, so modeled population sizes 
are likely smaller than their actual population size. The other marine 
mammal species that may be taken by harassment during SIO's seismic 
survey are not listed as threatened or endangered under the ESA. There 
is no designated critical habitat for any ESA-listed marine mammals 
within the project area.
    There are no rookeries, mating, or calving grounds known to be 
biologically important to marine mammals within the survey area, and 
there are no feeding areas known to be biologically important to marine 
mammals within the survey area.
    In summary and as described above, the following factors primarily 
support our determination that the impacts resulting from this activity 
are not expected to adversely affect any of the species or stocks 
through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or 
authorized;
     The planned activity is temporary and of relatively short 
duration (27 days total with 14 days of planned survey activity);
     The anticipated impacts of the planned activity on marine 
mammals would be temporary behavioral changes due to avoidance of the 
ensonified area, which is relatively small (see tables 4 and 5);
     The availability of alternative areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the planned survey to avoid exposure to sounds from the activity is 
readily abundant;
     The potential adverse effects on fish or invertebrate 
species that serve as prey

[[Page 101568]]

species for marine mammals from the planned survey would be temporary 
and spatially limited and impacts to marine mammal foraging would be 
minimal; and
     The planned mitigation measures are expected to reduce the 
number and severity of takes, to the extent practicable, by visually 
detecting marine mammals within the established zones and implementing 
corresponding mitigation measures (e.g., delay; shutdown).
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the planned monitoring and 
mitigation measures, NMFS finds that the total marine mammal take from 
the planned activity will have a negligible impact on all affected 
marine mammal species or stocks.

Small Numbers

    As noted previously, only take of small numbers of marine mammals 
may be authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    The number of takes NMFS is authorizing is below one-third of the 
modeled abundance for all relevant populations (specifically, take of 
individuals is less than 3 percent of the modeled abundance of each 
affected population, see table 6). This is conservative because the 
modeled abundance represents a population of the species and we assume 
all takes are of different individual animals, which is likely not the 
case. Some individuals may be encountered multiple times in a day, but 
PSOs would count them as separate individuals if they cannot be 
identified.
    Based on the analysis contained herein of the planned activity 
(including the mitigation and monitoring measures) and the anticipated 
take of marine mammals, NMFS finds that small numbers of marine mammals 
would be taken relative to the population size of the affected species 
or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
determined that the total taking of affected species or stocks would 
not have an unmitigable adverse impact on the availability of such 
species or stocks for taking for subsistence purposes.

Endangered Species Act

    Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.) 
requires that each Federal agency insure that any action it authorizes, 
funds, or carries out is not likely to jeopardize the continued 
existence of any endangered or threatened species or result in the 
destruction or adverse modification of designated critical habitat. To 
ensure ESA compliance for the issuance of IHAs, NMFS consults 
internally whenever we propose to authorize take for endangered or 
threatened species.
    The NMFS Office of Protected Resources (OPR) ESA Interagency 
Cooperation Division has issued a Biological Opinion under section 7 of 
the ESA, on the issuance of an IHA to NSF under section 101(a)(5)(D) of 
the MMPA by the NMFS OPR ESA Interagency Cooperation Division. The 
Biological Opinion concluded that the action is not likely to 
jeopardize the continued existence of ESA-listed humpback whales 
(Western North Pacific DPS), blue whales, fin whales, sei whales, and 
sperm whales.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our action (i.e., the issuance of an IHA) with respect 
to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or 
mortality) of the Companion Manual for NAO 216-6A, which do not 
individually or cumulatively have the potential for significant impacts 
on the quality of the human environment and for which we have not 
identified any extraordinary circumstances that would preclude this 
categorical exclusion. Accordingly, NMFS has determined that the 
issuance of the IHA qualifies to be categorically excluded from further 
NEPA review.

Authorization

    NMFS has issued an IHA to L-DEO for the potential harassment of 
small numbers of 28 marine mammal species incidental to the marine 
geophysical survey in the Nauru Basin of greater Micronesia in the NW 
Pacific Ocean that includes the previously explained mitigation, 
monitoring and reporting requirements.

    Dated: December 11, 2024.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2024-29552 Filed 12-13-24; 8:45 am]
BILLING CODE 3510-22-P