[Federal Register Volume 88, Number 186 (Wednesday, September 27, 2023)]
[Notices]
[Pages 66380-66392]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-21089]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD318]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Marine Geophysical Survey in 
Coastal Waters Off of Texas

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 marine geophysical survey activities in coastal waters 
off of Texas.

DATES: This Authorization is effective from September 29, 2023 through 
September 28, 2024.

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. Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et 
seq.) directs 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

[[Page 66381]]

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 mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

Summary of Request

    On March 7, 2023, NMFS received a request from UT for an IHA to 
take marine mammals incidental to conducting a marine geophysical 
survey in coastal waters off of Texas. Following NMFS' review of the 
application, UT submitted a revised version on April 25, 2023. The 
application was deemed adequate and complete on April 27, 2023. UT's 
request is for take of bottlenose dolphins, Atlantic spotted dolphins, 
and rough-toothed dolphin 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 the Specified Activity

Overview

    UT plans to conduct a marine geophysical survey, specifically a low 
energy seismic survey, in coastal waters off of Texas during a 10 day 
period in the fall of 2023. The survey will take place in water depths 
of less than 20 meters (m). To complete this survey the vessel will tow 
one to two Generator-Injector (GI) airguns, each with a volume of 105 
cubic inch (in\3\; 1,721 cubic cm (cm\3\)), for a total volume of 210 
in\3\ (3,441 cm\3\).
    The purpose of the planned survey is to validate novel dynamic 
positioning technology for improving the accuracy in time and space of 
high resolution 3-dimensional (HR3D) seismic datasets, in particular as 
it pertains to field technology of offshore carbon capture systems.

Dates and Duration

    The survey is planned to occur over a 10 day period during the fall 
of 2023 (the exact dates are uncertain). During that time, the airguns 
will operate continuously (i.e., 24-hours per day).

Specific Geographic Region

    The planned survey area is 222 square kilometers (km\2\) and will 
occur within the approximate area of 28.9-29.1[deg] N latitude, 94.9-
95.2[deg] W longitude in the coastal waters off of Texas. This location 
is offshore San Luis Pass, which defines the southern tip of Galveston 
Island, Texas. The closest point of approach of the planned survey area 
to the coast is approximately 3 km. The planned survey area is depicted 
in Figure 1, and the survey lines could occur anywhere within the 
survey area. The water depth of the planned survey area ranges from 10 
to 20 m. The survey vessel (the R/V Brooks McCall (McCall) or similar 
vessel operated by TDI-Brooks International) will likely depart and 
return to Freeport or Galveston, Texas.

[[Page 66382]]

[GRAPHIC] [TIFF OMITTED] TN27SE23.005

    A detailed description of the planned geophysical survey was 
provided in the Federal Register notice of the proposed IHA (88 FR 
53453, August 8, 2023). 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 UT was published in 
the Federal Register on August 8, 2023 (88 FR 53453). That notice 
described, in detail, UT's activities, the marine mammal species that 
may be affected by the activities, 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. This 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 
authorized for this activity 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 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

[[Page 66383]]

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 Likely Impacted by the Specified Activities \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                Gulf of
                                                                                             Stock abundance                                    Mexico
                                                                              ESA/ MMPA      (CV, Nmin, most                                  population
           Common name              Scientific name           Stock            status;      recent abundance           PBR         Annual M/   abundance
                                                                            strategic (Y/      survey) \3\                           SI \4\    (Roberts
                                                                                N) \2\                                                          et al.
                                                                                                                                                 2016)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Atlantic spotted dolphin....  Stenella frontalis.  Gulf of Mexico.....  -/-; N         21,506 (0.26;       166...............         36      47,488
                                                                                            17,339; 2018).
    Rough-toothed dolphin.......  Steno bredanensis..  Gulf of Mexico.....  -/-; N         unk (n/a; unk;      undetermined......         39       4,853
                                                                                            2018).
    Bottlenose dolphin..........  Tursiops truncatus.  Gulf of Mexico       -/-; N         20,759 (0.13;       167...............         36     138,602
                                                        Western Coastal.                    18,585; 2018).
                                                       Northern Gulf of     -/-; N         63,280 (0.11;       556...............         65     138,602
                                                        Mexico Continental                  57,917; 2018).
                                                        Shelf.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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/; Committee on Taxonomy (2022)).
\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-assessments assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\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, vessel strike). Annual M/SI (mortality/serious injury) often cannot be determined precisely and is in some cases presented as a
  minimum value or range.

    As indicated above, all 3 species (with 4 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. While the additional 11 species listed in Table 
2 of UT's application have been infrequently sighted in the survey 
area, the temporal and/or spatial occurrence of these species is such 
that take is not expected to occur, and they are not discussed further 
beyond the explanation provided here. Species or stocks that only occur 
in deep waters (>200 m) within the Gulf of Mexico are unlikely to be 
observed during this survey where the maximum water depth is 20 m, and 
thus, the following species or stocks will not be considered further: 
offshore stock of bottlenose dolphins, pantropical spotted dolphin, 
spinner dolphin, striped dolphin, Clymene dolphin, Fraser's dolphin, 
Risso's dolphin, melon-headed whale, pygmy killer whale, false killer 
whale, killer whale, and short-finned pilot whale.
    A detailed description 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 (88 FR 
53453, August 8, 2023); 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 modeling, etc.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65-
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 2.

                  Table 2--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
           Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans         7 hertz (Hz) to 35 kilohertz (kHz).
 (baleen whales).
Mid-frequency (MF) cetaceans         150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).

[[Page 66384]]

 
High-frequency (HF) cetaceans (true  275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)   50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)  60 Hz to 39 kHz.
 (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 are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information.

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 (88 FR 
53453, August 8, 2023) included a discussion of the effects of 
anthropogenic noise on marine mammals and the potential effects of 
underwater noise from UT 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 (88 FR 53453, August 8, 2023).

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
authorized through the IHA, which will inform both NMFS' consideration 
of ``small numbers,'' and the negligible impact determinations.
    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, 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 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 permanent threshold shift (PTS) 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 dB (re 1 
micropascal ([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 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-airgun) and therefore, the 160 dB re 1 [mu]Pa (rms) criterion 
is applicable for analysis of Level B harassment.

[[Page 66385]]

    Level A harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) 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). UT's 
planned survey includes the use of impulsive sources.
    These thresholds are provided in the Table 3 and 4 below. The 
references, analysis, and methodology used in the development of the 
thresholds are described in NMFS' 2018 Technical Guidance, which may be 
accessed at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

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.
    The planned survey will entail the use of up to two 105 in\3\ 
airguns with a maximum total discharge of 210 in\3\ at a tow depth of 
3-4 m. Lamont-Doherty Earth Observatory (L-DEO) model results were used 
to determine the 160 dBrms radius for the two-airgun array 
in water depths >100 m. Received sound levels were predicted by L-DEO's 
model (Diebold et al., 2010) as a function of distance from the airguns 
for the two 105 in\3\ airguns with a maximum total discharge of 210 
in\3\. 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 homogenous ocean 
layer, unbounded by a seafloor).
    The planned surveys will acquire data with up to two 105-in\3\ GI 
guns (separated by up to 2.4 m) at a tow depth of ~3-4 m. The shallow-
water radii are obtained by scaling the empirically derived 
measurements from the Gulf of Mexico 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 3.

 Table 3--Predicted Radial Distances From the R/V Brooks McCall Seismic
    Source to Isopleths Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
                                                           Predicted
                                                       distances (m) to
      Airgun configuration          Water depth (m)     160 dB received
                                                          sound level
------------------------------------------------------------------------
Two 105-in GI guns..............               <100           \1\ 1,750
------------------------------------------------------------------------
\1\ Distance is based on empirically derived measurements in the Gulf of
  Mexico with scaling applied to account for differences in tow depth.

    The ensonified area associated with Level A harassment is more 
technically challenging to predict due to the need to account for a 
duration component. Therefore, NMFS developed an optional user 
spreadsheet tool to accompany the Technical Guidance (2018) that can be 
used to relatively simply predict an isopleth distance for use in 
conjunction with marine mammal density or occurrence to help predict 
potential takes. We note that because of some of the assumptions 
included in the methods underlying this optional tool, we anticipate 
that the resulting isopleth estimates are typically going to be 
overestimates of some degree, which may result in an overestimate of 
potential take by Level A harassment. However, this optional tool 
offers the best way to estimate isopleth distances when more 
sophisticated modeling methods are not available or practical. Table 4 
presents the modeled PTS isopleths for mid-frequency cetaceans, the 
only hearing group for which takes are expected, based on L-DEO 
modeling incorporated in the companion User Spreadsheet (NMFS 2018).

 Table 4--Modeled Radial Distances to Isopleths Corresponding to Level A
                          Harassment Thresholds
------------------------------------------------------------------------
                        Hearing group                              MF
------------------------------------------------------------------------
PTS Peak.....................................................        1.5
PTS SELcum...................................................          0
------------------------------------------------------------------------

    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 (e.g., airguns) contained in the Technical Guidance 
(2018) were presented as dual metric acoustic thresholds using both 
cumulative sound energy (SELcum) and peak sound pressure 
metrics (NMFS 2016a). 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. In recognition of the fact that the requirement to 
calculate Level A harassment ensonified areas could be more technically 
challenging to predict due to the duration component and the use of 
weighting functions in the new SELcum thresholds, NMFS 
developed an optional User Spreadsheet that includes tools to help 
predict a simple isopleth that can be used in conjunction with marine 
mammal density or occurrence to facilitate the estimation of take 
numbers.
    The SELcum for the two-GI 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

[[Page 66386]]

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 interactions of the two 
airguns that occur near the source center and is calculated as a point 
source (single airgun), the modified farfield signature is a more 
appropriate measure of the sound source level for large arrays. For 
this smaller array, the modified farfield changes will be 
correspondingly smaller as well, but this method is used for 
consistency across all array sizes.
    Auditory injury for all species is unlikely to occur given the 
small modeled zones of injury (estimated zone less than 2 m for mid-
frequency cetaceans). Additionally, animals are expected to have 
aversive/compensatory behavior in response to the activity (Nachtigall 
et al., 2018) further limiting the likelihood of auditory injury for 
all species. UT did not request authorization of take by Level A 
harassment, and no take by Level A harassment is authorized by NMFS.

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 northwest Gulf of Mexico, 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. (2022). The Garrison et 
al. (2022) data provides abundance estimates for marine mammal species 
in the Gulf of Mexico 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 created a 7 km perimeter 
around the survey area and used that perimeter to select the density 
hexagons for each species in each month. The 7 km distance was chosen 
for the perimeter to ensure that at least one full density hexagon 
outside the survey area in all directions was selected, providing a 
more robust sample for the calculations. They then calculated the mean 
of the predicted densities from the selected cells for each species and 
month. The highest mean monthly density was chosen for each species 
from the months of September to December (i.e., the months within which 
the survey is expected to occur). NMFS concurred with this approach to 
calculate species density.
    Rough-toothed dolphins were not modeled by Garrison et al. (2022) 
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 Gulf of Mexico. The same 7 km 
perimeter described above 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 5.

Table 5--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\ 0.00082           7,866
Bottlenose dolphin \a\..................     \b\ 0.34024           7,866
Rough-toothed dolphin...................     \c\ 0.00362           7,866
------------------------------------------------------------------------
\a\ Bottlenose dolphin density estimate does not differentiate between
  coastal and shelf stocks.
\b\ Density calculated from Garrison et al. (2022).
\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 (10 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 takes for the planned survey are shown in Table 6.

[[Page 66387]]



                                                        Table 6--Estimated Take for Authorization
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                          Estimated take    Authorized
                                                                                         ----------------      take            Stock        Percent of
                    Species                                       Stock                                  ----------------  abundance \1\       stock
                                                                                              Level B         Level B
--------------------------------------------------------------------------------------------------------------------------------------------------------
Atlantic spotted dolphin.......................  Gulf of Mexico.........................               6          \2\ 26          21,506            0.12
Bottlenose dolphin \3\.........................  Gulf of Mexico Western Coastal.........           2,676           2,676          20,759           12.89
                                                 Northern Gulf of Mexico Continental                                              63,280            4.23
                                                  Shelf.
Rough-toothed dolphin..........................  Gulf of Mexico.........................              28              28       \3\ 4,853            0.58
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Stock abundance for Atlantic spotted dolphins and bottlenose dolphins was taken from Garrison et al. (2022). Stock abundance for rough-toothed
  dolphins was taken from Roberts et al. (2016), as Garrison et al. (2022) did not create a model for this species.
\2\ Estimated 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 estimated for authorization 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.
    Mitigation measures that will be adopted during the planned survey 
include, but are not limited to: (1) vessel speed or course alteration, 
provided that doing so would not compromise operation safety 
requirements; (2) monitoring a pre-start clearance zone; and (3) ramp-
up procedures.

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 3). 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 would 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 meters 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) three 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 is the gradual and systematic increase of emitted sound 
levels from an acoustic source. Ramp-up will begin with one GI airgun 
105 in\3\ first being activated, followed by the second after 5 
minutes. The intent of pre-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 ramp-up is to 
warn marine mammals in the vicinity of survey activities and to allow 
sufficient time for those animals to leave the immediate vicinity. A 
ramp-up procedure, involving a stepwise increase in the number of 
airguns are activated and the full volume is achieved, is required at 
all times as part of the activation of the

[[Page 66388]]

acoustic source. All operators must adhere to the following pre-
clearance and ramp-up requirements:
    (1) 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 the first airgun for 5 
minutes and then adding the second airgun; and
     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.
    (2) 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 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 and Steno are the only species 
expected to potentially be encountered, there is no shutdown 
requirement included in the IHA for species for which take is 
authorized.

Vessel Strike Avoidance Measures

    These measures apply to all vessels associated with the planned 
survey activity; however, we note that 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. These measures include the following:
    (1) 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 be exercised when an animal is observed. 
A visual observer aboard the vessel must monitor a vessel strike 
avoidance zone around the vessel (specific distances detailed below), 
to ensure the potential for strike is minimized. Visual observers 
monitoring the vessel strike avoidance zone can be either third-party 
observers 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 baleen whale, sperm whale, or other marine mammals;
    (2) Vessel speeds must be reduced to 10 knots (kn) (18.5 km/h) or 
less when mother and calf pairs, pods, or large assemblages of 
cetaceans are observed near a vessel;
    (3) All vessels must maintain a minimum separation distance of 100 
m from sperm whales;
    (4) All vessels must maintain a minimum separation distance of 500 
m baleen whales. If a baleen whale is sighted within the relevant 
separation distance, the vessel must steer a course away at 10 kn or 
less until the 500 m separation distance has been 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.
    (5) 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); and
    (6) When marine mammals are sighted while a vessel is underway, the 
vessel should 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). 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, 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

[[Page 66389]]

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. Two visual PSOs will be on duty at all time during 
daytime hours. Monitoring shall be conducted in accordance with the 
following requirements:
    (1) UT must 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, and to ensure that 
PSOs are capable of calibrating equipment as necessary for accurate 
distance estimates and species identification. See Condition 5(d) in 
the IHA for list of equipment.
    PSOs must have the following requirements and qualifications:
    (1) PSOs shall be independent, dedicated and trained and must be 
employed by a third-party observer provider;
    (2) PSOs shall have no tasks other than to conduct visual 
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);
    (3) PSOs shall have successfully completed an approved PSO training 
course appropriate for their designated task (visual);
    (4) 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;
    (5) 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;
    (6) 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 1 undergraduate course in math or 
statistics; and
    (7) 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 one week of receipt of submitted information. Alternate 
experience that may be considered includes, but is not limited to:
     Secondary education and/or experience comparable to PSO 
duties;
     Previous work experience conducting academic, commercial, 
or government-sponsored protected species surveys; or
     Previous work experience as a PSO; the PSO should 
demonstrate good standing and consistently good performance of PSO 
duties.
    At least one visual PSO must be unconditionally approved (i.e., 
have a minimum of 90 days at-sea experience working in that role at the 
particular Tier level (1-3) with no more than 18 months elapsed since 
the conclusion of the at-sea experience). One PSO with such experience 
shall be designated as the lead for the entire PSO team. The lead PSO 
shall serve as primary point of contact for the vessel operator. To the 
maximum extent practicable, the duty schedule shall be planned such 
that unconditionally-approved PSOs are on duty with conditionally-
approved PSOs.
    PSOs must use standardized electronic data collection forms. At a 
minimum, the following information must be recorded:
     Vessel name, vessel size and type, maximum speed 
capability of vessel;
     Dates (MM/DD/YYYY format) of departures and returns to 
port with port name;
     PSO names and affiliations, PSO identification (ID; 
initials or other identifier);
     Date (MM/DD/YYYY) and participants of PSO briefings;
     Visual monitoring equipment used (description);
     PSO location on vessel and height (in meters) of 
observation location above water surface;
     Watch status (description);
     Dates (MM/DD/YYYY) and times (Greenwich mean time (GMT) or 
coordinated universal time (UTC)) of survey on/off effort and times 
(GMC/UTC) corresponding with PSO on/off effort;
     Vessel location (decimal degrees) when survey effort began 
and ended and vessel location at beginning and end of visual PSO duty 
shifts;
     Vessel location (decimal degrees) at 30-second intervals 
if obtainable from data collection software, otherwise at practical 
regular interval;
     Vessel heading (compass heading) and speed (in knots) at 
beginning and end of visual PSO duty shifts and upon any change;
     Water depth (in meters) (if obtainable from data 
collection software);
     Environmental conditions while on visual survey (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including BSS and any other relevant weather conditions 
including cloud cover, fog, sun glare, and overall visibility to the 
horizon;
     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
     Vessel/Survey activity information (and changes thereof) 
(description), such as acoustic source power output while in operation, 
number and volume of acoustic source operating in the array, tow depth 
of the acoustic source, and any other notes of significance (i.e., pre-
start clearance, ramp-up, shutdown, testing, shooting, ramp-up 
completion, end of operations, streamers, etc.).
    The following information should be recorded upon visual 
observation of any marine mammal:
     Sighting ID (numeric);

[[Page 66390]]

     Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
     Location of PSO/observer (description);
     Vessel activity at the time of the sighting (e.g., 
deploying, recovering, testing, shooting, data acquisition, other);
     PSO who sighted the animal/PSO ID;
     Time and date of sighting (GMT/UTC, MM/DD/YYYY);
     Initial detection method (description);
     Sighting cue (description);
     Vessel location at time of sighting (decimal degrees);
     Water depth (in meters);
     Direction of vessel's travel (compass direction);
     Speed (knots) of the vessel from which the observation was 
made;
     Direction of animal's travel relative to the vessel 
(description, compass heading);
     Bearing to sighting (degrees);
     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;
     Species reliability (an indicator of confidence in 
identification) (1 = unsure/possible, 2 = probable, 3 = definite/sure, 
9 = unknown/not recorded);
     Estimated distance to the animal (meters) and method of 
estimating distance;
     Estimated number of animals (high, low, and best) 
(numeric);
     Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
     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);
     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);
     Animal's closest point of approach (in meters) and/or 
closest distance from any element of the acoustic source;
     Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up) and time and location of the 
action.
     Photos (Yes or No);
     Photo Frame Numbers (List of numbers); and
     Conditions at time of sighting (Visibility; BSS).

Reporting

    UT must submit a draft comprehensive report to NMFS 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 
will describe the activities that were conducted and sightings of 
marine mammals. The report will provide full documentation of methods, 
results, and interpretation pertaining to all monitoring. The 90 day 
report will summarize the dates and locations of survey operations, and 
all marine mammal sightings (dates, times, locations, activities, 
associated seismic survey activities).
    The draft report shall also include geo-referenced time-stamped 
vessel tracklines for all time periods during which airguns were 
operating. Tracklines should include points recording any change in 
airgun status (e.g., when the airguns began operating, when they were 
turned off, or when they changed from full array to single gun or vice 
versa). Geographic information system (GIS) files shall be provided in 
Environmental Systems Research Institute (ESRI) 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 to NMFS. A final report 
must be submitted within 30 days following resolution of any comments 
on the draft report.

Reporting Injured or Dead Marine Mammals

    Sighting of injured or dead marine mammals--In the event that 
personnel involved in survey activities covered by the authorization 
discover an injured or dead marine mammal, UT shall report the incident 
to the 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 vessel 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 to 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;
     Description of the behavior of the animal 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

[[Page 66391]]

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. 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 from low-energy survey, and no serious injury or 
mortality is proposed to be authorized. As discussed in the Potential 
Effects of Specified Activities on Marine Mammals and Their Habitat 
section, 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).
    In addition to being temporary, 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 (10 days) of the 
disturbance and the availability of similar habitat and resources in 
the surrounding area, the impacts to marine mammals and the food 
sources that they utilize are not expected to cause significant or 
long-term consequences for individual marine mammals or their 
populations.
    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 primarily 
support our determination that the impacts resulting from this activity 
are not expected to adversely affect the species or stock through 
effects on annual rates of recruitment or survival:
    (1) No serious injury or mortality is anticipated or authorized;
    (2) No Level A harassment is anticipated or authorized, even in the 
absence of mitigation measures;
    (3) Take is anticipated to be by Level B harassment only consisting 
of temporary behavioral changes of small percentages of the affected 
species due to avoidance of the area around the survey vessel. The 
relatively short duration of the planned survey (10 days) will further 
limit the potential impacts of any temporary behavioral changes that 
would occur;
    (4) The availability of alternate 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;
    (5) Foraging success is not likely to be significantly impacted as 
effects on prey species for marine mammals would be temporary and 
spatially limited; and
    (6) The mitigation measures, including visual monitoring, ramp-ups, 
and shutdowns are expected to minimize potential impacts to marine 
mammals.
    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 be authorized under section 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.
    NMFS is authorizing incidental take by Level B harassment of three 
marine mammal species with four managed stocks. The total amount of 
takes authorized relative to the best available population abundance is 
less than 5 percent for 3 managed stocks and less than 13 percent for 1 
managed stock (Gulf of Mexico Western Coastal stock of bottlenose 
dolphin assuming all takes by Level b harassment are of this stock; see 
Take Estimation subsection) (Table 6). The take numbers authorized are 
considered conservative estimates for purposes of the small numbers 
determination as they assume all takes represent different individual 
animals, which is unlikely to be the case.
    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 (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

[[Page 66392]]

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 is 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 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 NOAA Administrative Order 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 coastal waters off of Texas that includes the 
previously explained mitigation, monitoring and reporting requirements.

    Dated: September 22, 2023.
Catherine Marzin,
Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2023-21089 Filed 9-26-23; 8:45 am]
BILLING CODE 3510-22-P