`[Federal Register Volume 90, Number 11 (Friday, January 17, 2025)]
[Notices]
[Pages 5815-5826]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-01143]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XE594]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Marine Geophysical Survey in the 
Northwest Gulf of Mexico

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 University of Texas at Austin (UT) to incidentally harass marine 
mammals during survey activities associated with a marine geophysical 
survey in coastal waters off Texas in the northwest (NW) Gulf of Mexico 
(GOM).

DATES: This authorization is effective from January 13, 2025 through 
January 12, 2026.

ADDRESSES: Electronic copies of the application and supporting 
documents, as well as a list of the references cited in this document, 
may be obtained online at: https://www.fisheries.noaa.gov/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 specified 
geographical 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 used above are included in the relevant sections below 
and can be found in section 3 of the MMPA (16 U.S.C. 1362) and NMFS 
regulations at 50 CFR 216.103.

Summary of Request

    On July 25, 2024, NMFS received a request from UT for an IHA to 
take marine mammals incidental to a marine geophysical survey in 
coastal waters off Texas in the NW GOM. The application was deemed 
adequate and complete on September 24, 2024. UT's request is for take 
of bottlenose dolphins, Atlantic spotted dolphins, and rough-toothed 
dolphins, by Level B harassment only. Neither UT 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 UT plan to conduct a low-energy marine seismic 
survey using airguns as the acoustic source from the research vessel 
(R/V) Brooks McCall (McCall) or similar vessel operated by TDI-Brooks 
International. The planned survey will occur within Texas State waters 
in the NW GOM from approximately January to April 2025. The planned 
survey will occur within the Exclusive Economic Zone (EEZ) of the 
United States and in Texas State waters, in water depths less than 30 
meters (m). To complete this high resolution 3D (HR3D) seismic survey, 
the McCall will tow a 2-airgun array with a total discharge volume of 
~210 cubic inches (in\3\) at a depth of 3-4 meters (m), with a shot 
interval of 12.5 m (5-10 seconds (s)) as the primary acoustic source. 
The airgun array receiver will consist of four 25-m-long solid-state 
hydrophone streamers, spaced 10 m apart. Approximately 4,440 km of 
seismic acquisition is planned. The airgun array will introduce 
underwater sounds that may result in take, by Level B harassment only, 
of marine mammals.
    A detailed description of the planned marine geophysical survey is 
provided in the Federal Register notice for the proposed IHA (89 FR 
91340, November 19, 2024). Since that time, no changes have been made 
to the planned activities. Therefore, a detailed description is not 
provided here. Please refer to that Federal Register notice for a 
detailed description of the specific activity.

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to UT was published in 
the Federal Register on November 19, 2024 (89 FR 91340). That notice 
described, in detail, UT'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

[[Page 5816]]

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 regarding population trends and threats may be found in 
NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and 
more general information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 1 lists all species or stocks for which take is expected and 
may be taken as a result of the planned survey and summarizes 
information related to the population or stock, including regulatory 
status under the MMPA and Endangered Species Act (ESA) and potential 
biological removal (PBR), where known. PBR is 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 (as described in 
NMFS' SARs). While no serious injury or mortality is anticipated or 
authorized here, PBR and annual serious injury and mortality (M/SI) 
from anthropogenic sources are included here as gross indicators of the 
status of the species or stocks and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Atlantic and Gulf of Mexico SARs. All values presented in 
table 1 are the most recent available at the time of publication and 
are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                            Table 1--Species \1\ Likely Affected by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                              Stock abundance
                                                                               ESA/MMPA       (CV, Nmin, most                        Annual      GOM
           Common name              Scientific name           Stock             status;      recent abundance           PBR           M/SI    population
                                                                             strategic (Y/      survey) \3\                           \4\     abundance
                                                                                N) \2\                                                           \5\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  Odontoceti (toothed whales, dolphins, and porpoises)
                                                                   Family Delphinidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Atlantic spotted dolphin........  Stenella frontalis.  GOM................  -/-; N          21,506 (0.26;       166...............   \6\ 36   \7\ 12,240
                                                                                             17,339; 2018).
Rough-toothed dolphin...........  Steno bredanensis..  GOM................  -/-; N          unk (n/a; unk;      undetermined......       39        4,853
                                                                                             2018).
Bottlenose dolphin..............  Tursiops truncatus.  GOM Western Coastal  -/-; N          20,759 (0.13;       167...............       36  \7\ 151,886
                                                                                             18,585; 2018).
                                                       Northern GOM         -/-; N          63,280 (0.11;       556...............   \5\ 65
                                                        Continental Shelf.                   57,917; 2018).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
  (https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/).
\2\ 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.
\3\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\5\ Model-predicted stock abundance for Atlantic spotted dolphins and bottlenose dolphins from the most recent GOM density models (Garrison et al.,
  2023). Stock abundance for rough-toothed dolphins was taken from Roberts et al. (2016) density models, as Garrison et al. (2023) did not create a
  model for this species.
\6\ M/SI is a minimum count and does not include projected mortality estimates for 2015-2019 due to the DWH oil spill.
\7\ This estimate includes both coastal and continental shelf bottlenose dolphins from other stocks.

    As indicated above, all three species (with four managed stocks) 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 2 
of the IHA application.
    A detailed description of the species likely to be affected by the 
marine 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 91340, November 19, 2024); since that time, we are 
not aware of any changes in the status of these species and stocks; 
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

[[Page 5817]]

modeling, etc.). On October 24, 2024, NMFS published (89 FR 84872) the 
final Updated Technical Guidance, which includes updated thresholds and 
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                 Generalized hearing range *
------------------------------------------------------------------------
Underwater:
    Low-frequency (LF) cetaceans       7 Hz to 36 * kHz.
     (baleen whales).
    High-frequency (HF) cetaceans      150 Hz to 160 kHz.
     (dolphins, toothed whales,
     beaked whales, bottlenose
     whales).
    Very High-frequency (VHF)          200 Hz to 165 kHz.
     cetaceans (true porpoises,
     Kogia, river dolphins,
     Cephalorhynchid, Lagenorhynchus
     cruciger & L. australis).
    Phocid pinnipeds (PW)              40 Hz to 90 kHz.
     (underwater) (true seals).
    Otariid pinnipeds (OW)             60 Hz to 68 kHz.
     (underwater) (sea lions and fur
     seals).
------------------------------------------------------------------------
* 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.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effects of underwater noise from UT'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 
91340, November 19, 2024) included a discussion of the effects of 
anthropogenic noise on marine mammals and the potential effects of 
underwater noise from UT's survey activity on marine mammals and their 
habitat. That information and analysis is referenced in this final IHA 
determination and is not repeated here; please refer to the notice of 
proposed IHA (89 FR 91340, November 19, 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 
disruption of behavioral patterns for individual marine mammals 
resulting from exposure to sound from low energy seismic airguns. Based 
on the nature of the activity, i.e., use of a low energy 2-airgun 
array, auditory injury (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, 
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 decibels (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

[[Page 5818]]

thresholds are expected to include any likely takes by temporary 
threshold shift (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.
    UT's planned survey includes the use of impulsive seismic sources 
(e.g., GI-airguns) and therefore, the 160 dB re 1 [mu]Pa (rms) criteria 
is applicable for analysis of Level B harassment.
    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). UT's planned survey 
includes the use of impulsive seismic sources (i.e., airguns).
    UT previously used modeling based on NMFS' 2018 technical guidance 
in order to calculate their isopleths. Based on the outcome of these 
comparisons/analyses using the Updated 2024 Technical Guidance, the 
low-frequency and high-frequency (now very high-frequency) cetacean 
isopleths are slightly larger using the updated guidance, and the mid-
frequency (now high-frequency) cetacean isopleth is the same as those 
calculated using the 2018 Technical Guidance. As NMFS is only 
authorizing takes of mid-frequency (now high-frequency) cetaceans, the 
isopleths based on the 2018 Technical Guidance will be used as the 
basis for take numbers and mitigation zones for this IHA.
    The 2018 and 2024 thresholds are provided in the tables below. The 
references, analysis, and methodology used in the development of the 
thresholds are described in NMFS' 2018 Technical Guidance and 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.

                Table 3--NMFS' 2018 Thresholds Identifying the Onset of Permanent Threshold Shift
                                                      [PTS]
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1[micro]Pa\2\s. In this table, thresholds are abbreviated to reflect American
  National Standards Institute standards (ANSI, 2013). However, peak sound pressure is defined by ANSI as
  incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript
  ``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted within the
  generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates
  the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds)
  and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds 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 acoustic thresholds will be
  exceeded.


                     Table 4--NMFS' 2024 Thresholds Identifying the Onset of Auditory Injury
                                                    [AUD INJ]
----------------------------------------------------------------------------------------------------------------
                                                   AUD INJ onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 222 dB;   Cell 2: LE,LF,24h: 197 dB.
                                          LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans..........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,HF,24h: 201 dB.
                                          LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans....  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,VHF,24h: 181 dB.
                                          LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 223 dB;   Cell 8: LE,PW,24h: 195 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 230 dB;   Cell 10: LE,OW,24h: 199 dB.
                                          LE,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.


[[Page 5819]]

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 initially 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 
3D 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 up to two 105 in\3\ airguns 
with a maximum total discharge of 210 in\3\ at a tow depth of 3-4 m. UT 
used modeling by Lamont-Doherty Earth Observatory (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 2-airgun array. This modeling approach uses ray 
tracing for the direct wave traveling 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).
    The planned low-energy survey will acquire data with up to two 105-
in\3\ GI guns, towed in-line, at a depth of 3-4 m. The shallow-water 
radii are obtained by scaling the empirically derived measurements from 
the GOM calibration survey to account for the differences in volume and 
tow depth between the calibration survey (6,600 in\3\ at 6 m tow depth) 
and the planned survey (210 in\3\ at 4 m tow depth). A simple scaling 
factor is calculated from the ratios of the isopleths calculated by the 
deep-water L-DEO model, which are essentially a measure of the energy 
radiated by the source array.
    L-DEO's methodology is described in greater detail in UT's IHA 
application. The estimated distances to the Level B harassment isopleth 
for the planned airgun configuration are shown in table 5.

   Table 5--Predicted Radial Distances from the R/V McCall Seismic Source to Isopleth Corresponding to Level B
                                              Harassment Threshold
----------------------------------------------------------------------------------------------------------------
                                                                                                    Predicted
                                                                                                  distances (in
                     Airgun configuration                       Max tow depth   Water depth (m)  m) to the Level
                                                                     (m)                           B harassment
                                                                                                    threshold
----------------------------------------------------------------------------------------------------------------
2 105-in\3\ airguns..........................................               4             <100            1,750
----------------------------------------------------------------------------------------------------------------


 Table 6--Modeled Radial Distance to Isopleths Corresponding to Level A
                          Harassment Thresholds
                               [NMFS 2018]
------------------------------------------------------------------------
                                                           Mid frequency
                                                             cetaceans
------------------------------------------------------------------------
PTS SELcum..............................................               0
PTS Peak................................................           * 1.5
------------------------------------------------------------------------
* The largest distance of the dual criteria (cumulative SEL (SELcum) or
  Peak) was used to estimate threshold distances and potential takes by
  Level A harassment.

    Table 6 presents the modeled Level A harassment isopleths for the 
dolphin species considered here 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 or PTS based on accumulated sound energy) (NMFS 2018). Although 
NMFS' 2024 Updated Technical Guidance was finalized on October 24, 2024 
(89 FR 84872), a similar survey using four 105-in\3\ GI guns showed no 
difference in the auditory injury (Level A harassment) isopleths for 
delphinid species in the same hearing group (89 FR 81429, October 8, 
2024; 89 FR 101555, December 16, 2024), so the values based on the 2018 
guidance were used here.
    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 
SELcum and peak sound pressure metrics (NMFS, 2024). As dual 
metrics, NMFS considers onset of PTS (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 2-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 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

[[Page 5820]]

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 UT's application for further detail on acoustic 
modeling.
    Auditory injury is unlikely to occur for the dolphin species 
considered here, given the very small modeled zones of injury for those 
species (all estimated zones are less than 10 m), in the 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 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 of the dolphin species considered here 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 in the NW GOM, UT determined that the 
best source of density data for marine mammal species that might be 
encountered in the project area was habitat-based density modeling 
conducted by Garrison et al., (2023). The Garrison et al., (2023) data 
provides abundance estimates for marine mammal species in the GOM 
within 40 km\2\ hexagons (~3.9 km sides and ~7 km across from each 
side) on a monthly basis. To calculate expected densities specific to 
the survey area, UT calculated the mean of the predicted densities from 
the cells within the combined survey area (primary and alternate survey 
area) for each species and month. The highest mean monthly density was 
chosen for each species from the months of January to April (i.e., the 
months within which the survey is expected to occur).
    Rough-toothed dolphins were not modeled by Garrison et al., (2023) 
due to a lack of sightings, so habitat-based marine mammal density 
estimates from Roberts et al., (2016) were used. The Roberts et al., 
(2016) models consisted of 10 km x 10 km grid cells containing average 
annual densities for U.S. waters in the GOM. The combined survey area 
was used to select grid cells from the Roberts et al., (2016) dataset, 
and the mean of the selected grid cells for rough-toothed dolphins was 
calculated to estimate the annual average density of the species in the 
survey area. Estimated densities used and Level B harassment ensonified 
areas to inform take estimates are presented in table 7.

Table 7--Marine Mammal Densities and Total Ensonified Area of Activities
                       in the Planned Survey Area
------------------------------------------------------------------------
                                             Estimated        Level B
                 Species                    density (#/     ensonified
                                              km\2\)       area (km\2\)
------------------------------------------------------------------------
Atlantic spotted dolphin................      \b\ 0.0043           1,522
Bottlenose dolphin \a\..................      \b\ 0.8596           1,522
Rough-toothed dolphin...................      \c\ 0.0037           1,522
------------------------------------------------------------------------
\a\ Bottlenose dolphin density estimate does not differentiate between
  coastal and shelf stocks.
\b\ Density calculated from Garrison et al., (2023).
\c\ Density calculated from Roberts et al., (2016).

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 B harassment, radial distances from the airgun array to 
the predicted isopleth corresponding to the Level B harassment 
threshold was 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 area expected to be ensonified on 1 day was determined 
by multiplying the number of line km possible in 1 day by two times the 
160-dB radius plus adding endcaps to the start and beginning of the 
line. The daily ensonified area was then multiplied by the number of 
survey days (20 days). The highest mean monthly density for each 
species was then multiplied by the total ensonified area to calculate 
the estimated takes of each species.
    No takes by Level A harassment are expected or authorized. 
Estimated exposures and authorized take numbers are shown in table 8.

                                            Table 8--Authorized Take
----------------------------------------------------------------------------------------------------------------
                                                     Estimated      Authorized         Stock        Percent of
          Common name                 Stock        Level B take    Level B take    abundance \1\       stock
----------------------------------------------------------------------------------------------------------------
Atlantic spotted dolphin......  GOM.............               7          \2\ 26          21,506            0.12
Bottlenose dolphin \3\........  GOM Western                1,309           1,309          20,759            6.31
                                 Coastal.
                                Northern GOM                                              63,280            2.07
                                 Continental
                                 Shelf.
Rough-toothed dolphin.........  GOM.............               6          \2\ 14           4,853            0.29
----------------------------------------------------------------------------------------------------------------
\1\ Stock abundance for Atlantic spotted dolphins and bottlenose dolphins was taken from Garrison et al.,
  (2023). Stock abundance for rough-toothed dolphins was taken from Roberts et al., (2016), as Garrison et al.,
  (2023) did not create a model for this species.

[[Page 5821]]

 
\2\ Authorized take increased to mean group size from Maze-Foley and Mullin (2006).
\3\ Estimated take for bottlenose dolphins is not apportioned to stock, as density information does not
  differentiate between coastal and shelf dolphins. However, based on the planned survey depths, we expect that
  most of the takes would be from the coastal stock, but some takes could be from the shelf stock. Percent of
  stock was calculated as if all takes authorized accrued to the single stock with the lowest population
  abundance.

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-Visual Based Mitigation Monitoring

    Visual monitoring requires the use of trained observers (herein 
referred to as visual protected species observers (PSOs)) to scan the 
ocean surface visually for the presence of marine mammals. PSOs shall 
establish and monitor a pre-start clearance zone and, to the extent 
practicable, a Level B harassment zone (table 5). These zones shall be 
based upon the radial distance from the edges of the acoustic source 
(rather than being based on the center of the array or around the 
vessel itself). During pre-start clearance (i.e., before ramp-up 
begins), the pre-start clearance zone is the area in which observations 
of marine mammals within the zone will prevent airgun operations from 
beginning (i.e., ramp-up). The pre-start clearance zone encompasses the 
area at and below the sea surface out to a radius of 200 m from the 
edges of the airgun array.
    During survey operations (e.g., any day on which use of the 
acoustic source is planned to occur, and whenever the acoustic source 
is in the water, whether activated or not), a minimum of two 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 must begin no less than 30 
minutes prior to ramp-up and must continue until 1 hour after use of 
the acoustic source ceases or until 30 minutes past sunset. Visual PSOs 
must coordinate to ensure 360 degree visual coverage around the vessel 
from the most appropriate observation posts, and must 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 a pre-start clearance zone and to 
the extent practicable, a Level B harassment zone. These zones shall be 
based upon the radial distance from the edges of the acoustic source 
(rather than being based on the center of the array or around the 
vessel itself). 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 acoustic source is not operating for 
comparison of sightings rates and behavior with and without use of the 
acoustic source 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.

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 
prior to 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 PSOs time to monitor the pre-start clearance zone 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 pre-start clearance zone. If a marine mammal is observed 
within the pre-start clearance zone during the 30 minutes pre-clearance 
period, ramp-up may not begin until the animal(s) has been observed 
exiting the zone or until an additional time period has elapsed with no 
further sightings (15 minutes for small delphinids and 30 minutes for 
all other species).
     Ramp-up must begin by activating one GI airgun for no less 
than 5 minutes and then activating the second airgun. The operator must 
provide information to the PSO documenting that appropriate procedures 
were followed.

[[Page 5822]]

     PSOs must monitor the pre-start clearance zone during 
ramp-up, and ramp-up must cease and the source must be shut down upon 
detection of a marine mammal within the pre-start clearance zone. Once 
ramp-up has begun, observations of marine mammals for which take 
authorization is granted within the pre-start clearance zone does not 
require shutdown.
     If the acoustic source 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 
observation and no detections of marine mammals have occurred within 
the pre-start clearance zone. For any longer shutdown, pre-start 
clearance observation and ramp-up are required. Ramp-up may occur at 
times of poor visibility (e.g., BSS 4 or greater), including nighttime, 
if appropriate visual monitoring has occurred with no detections of 
marine mammals in the 30 minutes prior to beginning ramp-up. Acoustic 
source activation may only occur at night where operational planning 
cannot reasonably avoid such circumstances.
     Testing of the acoustic source involving all elements 
requires ramp-up. Testing limited to individual source elements or 
strings does not require ramp-up but does require a 30-minute pre-start 
clearance period.

Shutdown Procedures

    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. 
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. The shutdown requirement will be 
waived for small dolphins. As defined here, 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 specific 
genera of small dolphins- Steno, Stenella, and Tursiops. As Tursiops, 
Stenella, and Steno are the only species expected to potentially be 
encountered, there is no shutdown requirement included in the issued 
IHA for species for which take is authorized. UT 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 B harassment zone.
    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 the dolphin species considered here, as they are 
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 
McCall 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.

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 whale (defined in this context as sperm 
whales or baleen whales), or other marine mammals.
    Vessel speeds must be reduced to 10 knots (kn) (18.5 kph) or less 
when mother/calf pairs, pods, or large assemblages of cetaceans are 
observed near a vessel. The vessel must maintain a minimum separation 
distance of 500 m from baleen whales. If a baleen whale is sighted 
within the relevant separation distance, the vessel must steer a course 
away at 10 kn (18.5 kph) or less until the 500-m separation distance is 
established. If a whale is observed but cannot be confirmed as a 
species other than a baleen whale, the vessel operator must assume that 
it is a baleen whale and take appropriate action. All vessels must 
maintain a minimum separation distance of 100 m from sperm 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 
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.

[[Page 5823]]

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, 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. UT 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.
     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;
    [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;

[[Page 5824]]

    [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 (knots) 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.).
     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 (knots) 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; BSS).

Reporting

    UT 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, UT shall report the incident to the Office of Protected 
Resources (OPR), NMFS and the NMFS, Southeast Regional Stranding 
Coordinator 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, UT 
shall report the incident to OPR, NMFS, and the NMFS Southeast Regional 
Stranding Coordinator 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);
     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;

[[Page 5825]]

     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 
Atlantic spotted dolphins, bottlenose dolphins, and rough-toothed 
dolphins, given that the anticipated effects of this activity on these 
different marine mammal stocks are expected to be similar. There is 
little information about the nature or severity of the impacts, or the 
size, status, or structure of any of these species or stocks that would 
lead to a different analysis for this activity.
    NMFS does not anticipate that serious injury or mortality would 
occur as a result of UT'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 will 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, auditory injury (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 1,750 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 (20 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 planned survey. However, the very brief overall duration of the 
planned survey (20 survey days) will further limit potential impacts 
that may occur as a result of the planned activity.
    There are no rookeries, mating, or calving grounds known to be 
biologically important to marine mammals within the planned survey area 
and there are no feeding areas known to be biologically important to 
marine mammals within the survey area. There is no designated critical 
habitat for any ESA-listed marine mammals within the project area.
    In summary and as described above, the following factors 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;
     No auditory injury (Level A harassment) is anticipated or 
authorized;
     The planned activity is temporary and of relatively short 
duration (23 days total with 20 days of planned survey activity);
     The anticipated impacts of the planned activity on marine 
mammals will be temporary behavioral changes due to avoidance of the 
ensonified area, which is relatively small (see tables 5 and 6);
     The availability of alternative areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the 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 species for marine mammals from the planned 
survey will be temporary and spatially limited and impacts to marine 
mammal foraging will be minimal; and
     The 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; ramp-up).
    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 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

[[Page 5826]]

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 7 percent of the most appropriate abundance 
estimate for each stock, see table 7). This is conservative because 
this approach assumes 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.
    No incidental take of ESA-listed species are authorized or expected 
to result from this activity. Therefore, NMFS has determined that 
formal consultation under section 7 of the ESA is not required for this 
action.

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 proposed 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 UT for the potential harassment of small 
numbers of three marine mammal species incidental to the marine 
geophysical survey in the NW GOM that includes the previously explained 
mitigation, monitoring, and reporting requirements.

    Dated: January 14, 2025.
Catherine Marzin,
Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2025-01143 Filed 1-16-25; 8:45 am]
BILLING CODE 3510-22-P`