[Federal Register Volume 87, Number 128 (Wednesday, July 6, 2022)]
[Notices]
[Pages 40186-40200]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-14362]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XB760]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Geophysical Surveys in the 
Southeastern Gulf of Mexico

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

ACTION: Notice; issuance of an incidental harassment authorization 
(IHA).

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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 IHA to Scripps Institution of Oceanography 
(Scripps) to incidentally harass marine mammals during marine 
geophysical surveys in the southeastern Gulf of Mexico.

DATES: This authorization is effective from June 29, 2022 through June 
28, 2023.

FOR FURTHER INFORMATION CONTACT: Amy Fowler, Office of Protected 
Resources, NMFS, (301) 427-8401. 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/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these 
documents, please call the contact listed above.

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 incidental harassment authorization 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 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 17, 2020, NMFS received a request from Scripps for an IHA 
to take marine mammals incidental to low-energy geophysical surveys in 
the southeastern Gulf of Mexico, initially planned to occur in summer 
2020. The application was deemed adequate and complete on May 26, 2020. 
On June 9, 2020, Scripps notified NMFS that the proposed survey had 
been postponed and tentatively rescheduled for summer 2021. On April 8, 
2021, Scripps notified NMFS that the survey had been further postponed 
and is now expected to occur in July-August 2022. NMFS reviewed recent 
draft Stock Assessment Reports (SARs) and other scientific literature, 
and determined that neither this nor any other new information affects 
which species or stocks have the potential to be affected, the 
potential effects to marine mammals and their habitat as described in 
the IHA application, or any other aspect of the analysis. Therefore, 
NMFS determined that Scripps' IHA application remained adequate and 
complete. Scripps' request is for take of 20 species of marine mammals 
by Level B harassment only. Neither Scripps nor NMFS expects serious 
injury or mortality to result from this activity and, therefore, an IHA 
is appropriate.

Description of Activity

Overview

    Scripps plans to support a research project that involves low-
energy seismic surveys in the Gulf of Mexico during summer 2022. The 
study will be conducted on the R/V Justo Sierra, owned by Universidad 
Nacional Aut[oacute]noma de M[eacute]xico (UNAM), using a portable 
multi-channel seismic (MCS) system operated by marine technicians from 
Scripps. The survey will use a pair of low-energy Generator-Injector 
(GI) airguns with a total discharge volume of 90 cubic inches (in\3\). 
The surveys will take place within the Exclusive Economic Zones (EEZs) 
of Mexico and Cuba in the southeastern Gulf of Mexico.

Dates and Duration

    The specific dates of the survey have not been determined but the 
cruise is expected to occur in July to August 2022. The research cruise 
is expected to consist of 15 days at sea, including ~12 days of seismic 
operations (10 planned days and 2 contingency days) and ~3 days of 
transit. R/V Justo Sierra will depart from Tampamochaco, Mexico

[[Page 40187]]

and return to Progreso, Mexico after the program is completed.

Specific Geographic Region

    The planned surveys take place in the Gulf of Mexico between 
~22[deg]-25[deg] N and 83.8[deg]-88[deg] W (see Figure 1). Seismic 
acquisition will occur in two primary survey areas. The Yucat[aacute]n 
Channel survey area is located in the deep-water channel between the 
Campeche and Florida escarpments, within the EEZ of Cuba in water 
depths ranging from ~1,500 to 3,600 meters (m; 4,921 to 11,811 feet 
(ft)). The Campeche Bank survey area is located in the northeastern 
flank of the Campeche escarpment, within the EEZs of Cuba and Mexico in 
waters ranging in depth from ~110 to 3,000 m (361 to 9,843 ft).
[GRAPHIC] [TIFF OMITTED] TN06JY22.007

    A detailed description of the planned geophysical survey project is 
provided in the Federal Register notice for the proposed IHA (86 FR 
71427; December 16, 2021). 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.
    Mitigation, monitoring, and reporting measures are described in 
detail later in this document (please see Mitigation and Monitoring and 
Reporting).

Comments and Responses

    A notice of proposed IHA was published in the Federal Register on 
December 16, 2021 (86 FR 71427). That notice described, in detail, 
Scripps' activity, the marine mammal species that may be affected by 
the activity, and the anticipated effects on marine mammals. During the 
30-day public comment period, NMFS did not receive any 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. 
Additional information regarding population trends and threats may be 
found in NMFS's 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's website (https://www.fisheries.noaa.gov/find-species).
    Table 1 lists all species or stocks for which take is expected and 
has been authorized for this action, 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. For taxonomy, we follow Committee on Taxonomy 
(2021). 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's SARs). While no 
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 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's stock

[[Page 40188]]

abundance estimates for most species represent the total estimate of 
individuals within the geographic area, if known, that comprises that 
stock. For most species, stock abundance estimates are based on 
sightings within the U.S. EEZ, however for some species, this 
geographic area may extend beyond U.S. waters. Other species may use 
survey abundance estimates. Survey abundance (as compared to stock or 
species abundance) is the total number of individuals estimated within 
the survey area, which may or may not align completely with a stock's 
geographic range as defined in the SARs. These surveys may also extend 
beyond U.S. waters. In this case, the planned survey area outside of 
the U.S. EEZ does not necessarily overlap with the ranges for stocks 
managed by NMFS. However, we assume that individuals of these species 
that may be encountered during the survey may be part of those stocks.
    All managed stocks in this region are assessed in NMFS's U.S. 
Atlantic and Gulf of Mexico SARs (e.g., Hayes et al., 2021). All values 
presented in Table 1 are the most recent available at the time of 
publication and are available in the 2020 SARs (Hayes et al., 2021) and 
draft 2021 SARs (available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).
    For the majority of species potentially present in the specified 
geographical region, NMFS has designated only a single generic stock 
(i.e., ``Gulf of Mexico'') for management purposes, although there is 
currently no information to differentiate the stock from the Atlantic 
Ocean stock of the same species, nor information on whether more than 
one stock may exist in the GOM (Hayes et al., 2017).

                                               Table 1--Marine Mammals That Could Occur in the Survey Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                               Gulf of
                                                                                          Stock abundance                                       Mexico
                                                                            ESA/MMPA      (CV, Nmin, most                                     population
          Common name              Scientific name          Stock           status;      recent abundance           PBR         Annual M/SI   abundance
                                                                         strategic  (Y/     survey) \2\                             \3\      (Roberts et
                                                                             N) \1\                                                           al., 2016)
                                                                                                                                                 \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                            Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale................  Physeter            Gulf of Mexico....  E/D; Y         1,180 (0.22, 983,   2.................          9.6        2,207
                                  macrocephalus.                                         2018).
Family Kogiidae:
    Pygmy sperm whale \6\......  Kogia breviceps...  Gulf of Mexico....  -/-; N         336 (0.35, 253,     2.5...............           31        4,373
                                                                                         2018).
    Dwarf sperm whale \6\......  Kogia sima........
Family Ziphiidae (beaked
 whales):
    Cuvier's beaked whale \6\..  Ziphius cavirstris  Gulf of Mexico....  -/-; N         18 (0.75, 10,       0.1...............          5.2        3,768
                                                                                         2018).
    Blainville's beaked whale    Mesoplodon          Gulf of Mexico....  -/-; N         98 (0.46, 68,       0.7...............          5.2
     \6\.                         densirostris.                                          2018).
    Gervais' beaked whale \6\..  Mesoplodon          Gulf of Mexico....  -/-; N         20 (0.98, 10,       0.1...............          5.2
                                  europaeus.                                             2018).
Family Delphinidae:
    Rough-toothed dolphin......  Steno bredanensis.  Gulf of Mexico....  -/-; N         unknown (n/a,       undetermined......           39        4,853
                                                                                         unknown, 2018).
    Bottlenose dolphin.........  Tursiops truncatus  Gulf of Mexico      -/-; N         7,462 (0.31,        58................           32  \6\ 176,108
                                                      Oceanic.                           5,769, 2018).
    Pantropical spotted dolphin  Stenella attenuata  Gulf of Mexico....  -/-; N         37,195 (0.24,       304...............          241      102,361
                                                                                         30,377, 2018).
    Atlantic spotted dolphin...  Stenella frontalis  Gulf of Mexico....  -/-; N         21,506 (0.26,       166...............           36       74,785
                                                                                         17,339, 2018).
    Spinner dolphin............  Stenella            Gulf of Mexico....  -/-; Y         2,991 (0.54,        20................          113       25,114
                                  longirostris.                                          1,954, 2018).
    Clymene dolphin............  Stenella clymene..  Gulf of Mexico....  -/-; Y         513 (1.03, 250,     2.5...............          8.4       11,895
                                                                                         2018).
    Striped dolphin............  Stenella            Gulf of Mexico....  -/-; Y         1,817 (0.56,        12................           13        5,229
                                  coeruleoalba.                                          1,172, 2018).
    Fraser's dolphin...........  Lagenodelphis       Gulf of Mexico....  -/-; N         213 (1.03, 104,     1.................      Unknown        1,665
                                  hosei.                                                 2018).
    Risso's dolphin............  Grampus griseus...  Gulf of Mexico....  -/-; N         1,974 (0.46,        14................          5.3        3,764
                                                                                         1,368, 2018).
    Melon-headed whale.........  Peponocephala       Gulf of Mexico....  -/-; N         1,749 (0.68,        10................          9.5        7,003
                                  electra.                                               1,039, 2018).
    Pygmy killer whale.........  Feresa attenuata..  Gulf of Mexico....  -/-; N         613 (1.15, 283,     2.8...............          1.6        2,126
                                                                                         2018).
    False killer whale.........  Pseudorca           Gulf of Mexico....  -/-; N         494 (0.79, 276,     2.8...............      Unknown        3,204
                                  crassidens.                                            2018).
    Killer whale...............  Orcinus orca......  Gulf of Mexico....  -/-; N         267 (0.75, 152,     1.5...............      Unknown          185
                                                                                         2018).
    Short-finned pilot whale...  Globicephalus       Gulf of Mexico....  -/-; N         1,321 (0.43, 934,   7.5...............          3.9        1,981
                                  macrorhynchus.                                         2018).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\3\ 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 mortality/serious injury (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.
\4\ This information represents species- or guild-specific best abundance estimate predicted by habitat-based cetacean density models (Roberts et al.,
  2016). These models provide the best available scientific information regarding predicted density patterns of cetaceans in the U.S. Gulf of Mexico,
  and we provide the corresponding abundance predictions as a point of reference. Total abundance estimates were produced by computing the mean density
  of all pixels in the modeled area and multiplying by its area. For those taxa where a density surface model predicting abundance by month was
  produced, the maximum mean seasonal abundance was used. For those taxa where abundance is not predicted by month, only mean annual abundance is
  available. For more information, see https://seamap.env.duke.edu/models/Duke/GOM/.
\5\ Abundance estimates are in some cases reported for a guild or group of species when those species are difficult to differentiate at sea. Similarly,
  the habitat-based cetacean density models produced by Roberts et al. (2016) are based in part on available observational data which, in some cases, is
  limited to genus or guild in terms of taxonomic definition. NMFS's SARs present pooled abundance estimates for Kogia spp. and Mesoplodon spp., while
  Roberts et al. (2016) produced density models to genus level for Kogia spp. and as a guild for beaked whales (Ziphius cavirostris and Mesoplodon
  spp.). Finally, Roberts et al. (2016) produced a density model for bottlenose dolphins that does not differentiate between oceanic, shelf, and coastal
  stocks.


[[Page 40189]]

    In Table 1 above, we report two sets of abundance estimates: those 
from NMFS SARs and those predicted by Roberts et al. (2016). Please see 
the table footnotes for more detail. As discussed in the notice of 
proposed IHA (86 FR 71427; December 16, 2021), we expect that the 
Roberts et al. (2016) estimates are generally more realistic and, for 
these purposes, represent the best available information. For purposes 
of assessing estimated exposures relative to abundance--used in this 
case to understand the scale of the predicted takes compared to the 
population--we generally believe that the Roberts et al. (2016) 
abundance predictions are most appropriate because they were used to 
generate the exposure estimates and therefore provide the most relevant 
comparison (see Estimated Take). Roberts et al. (2016) represents the 
best available scientific information regarding marine mammal 
occurrence and distribution in the Gulf of Mexico.
    As the planned survey lines are outside of the U.S. EEZ, they do 
not directly overlap with the defined stock ranges within the Gulf of 
Mexico (Hayes et al., 2021). However, some of the survey lines occur 
near the U.S. EEZ, and the distribution and abundance of species in 
U.S. EEZ waters are assumed representative of those in the survey area. 
As indicated above, all 20 species (with 20 representative stocks in 
the northern Gulf of Mexico) in Table 1 temporally and spatially co-
occur with the activity to the degree that take is reasonably likely to 
occur, and we have authorized it. 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 
geophysical surveys, 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 Scripps' IHA application and summarized in the Federal 
Register notice for the proposed IHA (86 FR 71427; December 16, 2021); 
since that time, we are not aware of any changes in the status of these 
species or stocks; therefore, detailed descriptions are not provided 
here. Please refer to that Federal Register notice and the IHA 
application for these descriptions. Please also refer to NMFS' website 
(www.nmfs.noaa.gov/pr/species/mammals/) 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. Current data indicate that 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) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. 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 (baleen   7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans           150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
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).

    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Twenty species of cetacean have the reasonable potential to co-occur 
with the planned survey activities. No pinnipeds are expected to be 
present or taken. Of the cetacean species that may be present, 18 are 
classified as mid-frequency cetaceans (i.e., all delphinid and ziphiid 
species and the sperm whale) and two are classified as high-frequency 
cetaceans (i.e., Kogia spp.). No low-frequency cetaceans (i.e., baleen 
whales) are expected to be present or taken.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effects of underwater noise from Scripps' geophysical 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 (86 FR 71427; December 16, 2021) included a discussion of 
the effects of anthropogenic noise on marine mammals and the potential 
effects of underwater noise from Scripps' geophysical survey activities 
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 (86 FR 71427; 
December 16, 2021). The referenced information includes a summary and 
discussion of the ways that the specified activity may impact marine 
mammals and their habitat. Consistent with the analysis in our prior 
Federal Register notices for similar Scripps surveys and after 
independently evaluating the analysis in Scripps'

[[Page 40190]]

application, we determine that the survey is likely to result in the 
takes described in the Estimated Take section of this document and that 
other forms of take are not expected to occur.
    The Estimated Take section later in this document includes a 
quantitative analysis of the number of individuals that are expected to 
be taken by this activity. The Negligible Impact Analysis and 
Determination section considers the content of this section, the 
Estimated Take section, and the Mitigation section, to draw conclusions 
regarding the likely impacts of these activities on the reproductive 
success or survivorship of individuals and how those impacts on 
individuals are likely to impact marine mammal species or stocks.

Estimated Take

    This section provides an estimate of the number of incidental takes 
authorized through this IHA, which informs both NMFS' consideration of 
``small numbers'' and the negligible impact determination.
    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 are by Level B harassment only, as use of the 
acoustic sources (i.e., seismic airgun) has the potential to result in 
disruption of behavioral patterns for individual marine mammals. Based 
on the nature of the activity and the anticipated effectiveness of the 
mitigation measures (i.e., marine mammal exclusion zones) discussed in 
detail below in Mitigation section, Level A harassment is neither 
anticipated nor authorized. As described previously, no mortality is 
anticipated or authorized for this activity. Below we describe how the 
take is estimated.
    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 basic 
factors can contribute to a basic calculation to provide an initial 
prediction of 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 estimated and 
authorized take.

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 PTS of some degree (equated to Level A 
harassment).
    Level B Harassment for non-explosive sources--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 (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). Based on what the available science indicates 
and the practical need to use a threshold based on a factor that is 
both predictable and measurable for most activities, NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of behavioral harassment. NMFS predicts that marine mammals are 
likely to be behaviorally harassed in a manner we consider Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 microPascal ([mu]Pa) root mean square 
(rms) for continuous (e.g., vibratory pile-driving, drilling) and above 
160 dB re 1 [mu]Pa (rms) for non-explosive impulsive (e.g., seismic 
airguns) or intermittent (e.g., scientific sonar) sources.
    Scripps' activity includes the use of impulsive seismic sources, 
and therefore the 160 dB re 1 [mu]Pa (rms) is applicable.
    Level A harassment for non-explosive sources--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). Scripps' activity includes the use of 
impulsive seismic sources.
    These thresholds are provided in the table 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.

                  Table 3--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.

[[Page 40191]]

 
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.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    The survey entails the use of a 2-airgun array with a total 
discharge of 90 in\3\ at a tow depth of 2-4 m. Lamont-Doherty Earth 
Observatory (L-DEO) model results are used to determine the 160 
dB<INF>rms</INF> radius for the 2-airgun array in deep water (> 1,000 
m) down to a maximum water depth of 2,000 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 45 in\3\ airguns. 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). 
In addition, propagation measurements of pulses from a 36-airgun array 
at a tow depth of 6 m have been reported in deep water (~1,600 m), 
intermediate water depth on the slope (~600-1,100 m), and shallow water 
(~50 m) in the Gulf of Mexico in 2007-2008 (Tolstoy et al., 2009; 
Diebold et al., 2010).
    For deep and intermediate water cases, the field measurements 
cannot be used readily to derive the Level A and Level B harassment 
isopleths, as at those sites the calibration hydrophone was located at 
a roughly constant depth of 350-550 m, which may not intersect all the 
sound pressure level (SPL) isopleths at their widest point from the sea 
surface down to the maximum relevant water depth (~2,000 m) for marine 
mammals. At short ranges, where the direct arrivals dominate and the 
effects of seafloor interactions are minimal, the data at the deep 
sites are suitable for comparison with modeled levels at the depth of 
the calibration hydrophone. At longer ranges, the comparison with the 
model--constructed from the maximum SPL through the entire water column 
at varying distances from the airgun array--is the most relevant.
    In deep and intermediate water depths, comparisons at short ranges 
between sound levels for direct arrivals recorded by the calibration 
hydrophone and model results for the same array tow depth are in good 
agreement (see Figures 12 and 14 in Appendix H of NSF-USGS 2011). 
Consequently, isopleths falling within this domain can be predicted 
reliably by the L-DEO model, although they may be imperfectly sampled 
by measurements recorded at a single depth. At greater distances, the 
calibration data show that seafloor-reflected and sub-seafloor-
refracted arrivals dominate, whereas the direct arrivals become weak 
and/or incoherent. Aside from local topography effects, the region 
around the critical distance is where the observed levels rise closest 
to the model curve. However, the observed sound levels are found to 
fall almost entirely below the model curve. Thus, analysis of the Gulf 
of Mexico calibration measurements demonstrates that although simple, 
the L-DEO model is a robust tool for conservatively estimating 
isopleths.
    The planned surveys will acquire data with two 45-in\3\ guns at a 
tow depth of 2-4 m. For deep water (>1000 m), we use the deep-water 
radii obtained from L-DEO model results down to a maximum water depth 
of 2,000 m for the airgun array with 2-m airgun separation. The radii 
for intermediate water depths (100-1,000 m) are derived from the deep-
water ones by applying a correction factor (multiplication) of 1.5, 
such that observed levels at very near offsets fall below the corrected 
mitigation curve (see Figure 16 in Appendix H of NSF-USGS 2011). No 
survey effort is planned to occur in shallow water (<100 m).
    L-DEO's modeling methodology is described in greater detail in 
SIO's IHA application. The estimated distances to the Level B 
harassment isopleths for the planned airgun configuration in each water 
depth category are shown in Table 4.

Table 4--Predicted Radial Distances From R/V Justo Sierra Seismic Source
       to Isopleths Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
                                                             Predicted
                                                           distances (m)
          Airgun configuration              Water depth    to 160 dB rms
                                                (m)        SPL received
                                                            sound level
------------------------------------------------------------------------
Two 45 in\3\ guns, 2-m separation, 4-m            >1,000         \a\ 539
 tow depth..............................       100-1,000         \b\ 809
------------------------------------------------------------------------
\a\ Distance based on L-DEO model results.
\b\ Distance based on L-DEO model results with a 1.5 x correction factor
  between deep and intermediate water depths.

    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. The updated acoustic thresholds for onset of 
hearing impacts from impulsive sounds (e.g., airguns) contained in the 
Technical Guidance were presented as dual metric acoustic thresholds 
using both cumulative sound exposure level (SEL<INF>cum</INF>) 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 SEL<INF>cum</INF> 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

[[Page 40192]]

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 SEL<INF>cum</INF> 
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 SEL<INF>cum</INF> for the 2-GI airgun array is derived from 
calculating the modified far-field signature. The far-field signature 
is often used as a theoretical representation of the source level. To 
compute the far-field signature, the source level is estimated at a 
large distance 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 far-field 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 far-field 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 far-field signature. Because the far-field 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 far-field signature is a more appropriate 
measure of the sound source level for large arrays. For this smaller 
array, the modified far-field changes will be correspondingly smaller 
as well, but we use this method for consistency across all array sizes.
    Scripps used the same acoustic modeling as for Level B harassment 
with a small grid step in both the inline and depth directions to 
estimate the SEL<INF>cum</INF> and peak SPL. The propagation modeling 
takes into account all airgun interactions at short distances from the 
source including interactions between subarrays using the NUCLEUS 
software to estimate the notional signature and the MATLAB software to 
calculate the pressure signal at each mesh point of a grid. For a more 
complete explanation of this modeling approach, please see ``Appendix 
A: Determination of Mitigation Zones'' in Scripps' IHA application.
    In order to more realistically incorporate the Technical Guidance's 
weighting functions over the seismic array's full acoustic band, 
unweighted spectrum data for the airgun array (modeled in 1 Hertz (Hz) 
bands) was used to make adjustments (dB) to the unweighted spectrum 
levels, by frequency, according to the weighting functions for each 
relevant marine mammal hearing group. These adjusted/weighted spectrum 
levels were then converted to pressures ([mu]Pa) in order to integrate 
them over the entire broadband spectrum, resulting in broadband 
weighted source levels by hearing group that could be directly 
incorporated within the User Spreadsheet (i.e., to override the 
Spreadsheet's more simple weighting factor adjustment). Using the User 
Spreadsheet's ``safe distance'' methodology for mobile sources 
(described by Sivle et al., 2014) with the hearing group-specific 
weighted source levels, and inputs assuming spherical spreading 
propagation and source velocities and shot intervals provided in 
Scripps' IHA application, potential radial distances to auditory injury 
zones were calculated for PTS thresholds. Calculated Level A harassment 
zones for all cetacean hearing groups are presented in Table 5 below 
(no pinnipeds are expected to occur in the survey area).

   Table 5--Modeled Radial Distances (m) to Isopleths Corresponding to
                      Level A Harassment Thresholds
------------------------------------------------------------------------
                                                                Level A
                  Functional hearing group                    harassment
                                                               zone  (m)
------------------------------------------------------------------------
Low-frequency cetaceans \1\.................................         9.9
Mid-frequency cetaceans.....................................         1.0
High-frequency cetaceans....................................        34.6
------------------------------------------------------------------------
\1\ Low-frequency cetaceans are not expected to be encountered or taken
  by Level A or Level B harassment during the survey.

    Note that because of some of the assumptions included in the 
methods used, isopleths produced may be overestimates to some degree, 
which will ultimately result in some degree of overestimate of the 
potential for take by Level A harassment. 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. For mobile sources, such as the 
planned seismic survey, the User Spreadsheet predicts the closest 
distance at which a stationary animal would not incur PTS if the sound 
source traveled by the animal in a straight line at a constant speed.
    Auditory injury is unlikely to occur for any functional hearing 
group given the very small modeled zones of injury (all estimated zones 
less than 35 meters (m)), and we therefore 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. Additionally, the method of 
estimating take as described below (see Take Calculation and 
Estimation) yielded only two species/guilds with calculated takes by 
Level A harassment, and the highest calculated take of those two groups 
was only two takes by Level A harassment (Table 9). We do not believe 
that Level A harassment is a likely outcome for any hearing group and 
have not authorized take by Level A harassment for any species.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations.
    For the planned survey area in the southeast Gulf of Mexico, 
Scripps 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 Roberts et al. (2016). The 
Roberts et al. (2016) data provide abundance estimates for species or 
species guilds within 10 km x 10 km grid cells (100 square kilometer 
(km\2\)) within the U.S. EEZ in the Gulf of Mexico and Atlantic Ocean 
on a monthly or annual basis, depending on the species and location. In 
the Gulf of Mexico, marine mammals do not migrate seasonally, so a 
single estimate for each grid cell is provided and represents the 
predicted abundance of that species in that 100 km\2\ location at any 
time of year.
    As the planned survey lines are outside of the U.S. EEZ, they do 
not directly overlap the available spatial density data. However, some 
of the survey lines occur near the U.S. EEZ, and the distribution and 
abundance of species in U.S. EEZ waters are assumed representative of 
those in the nearby survey area. To select a representative

[[Page 40193]]

sample of grid cells for the calculation of densities in three 
different water depth categories (>100 m, 100-1,000 m, and >1,000 m), a 
200-km perimeter around the survey lines was created in GIS. The areas 
within this perimeter within the three depth categories was then used 
to select grid cells containing the estimates for each species in the 
Roberts et al. (2016) data (i.e., <100 m, n = 157 grid cells; 100-
1,000, n = 169 grid cells; >1,000 m, n = 410 grid cells). The average 
abundance for each species in each water depth category was calculated 
as the mean value of the grid cells within each category and then 
converted to density (individuals/1 km\2\) by dividing by 100 km\2\. 
Estimated densities for marine mammal species that could occur in the 
project area are shown in Table 6.

           Table 6--Marine Mammal Densities in the Survey Area
------------------------------------------------------------------------
                                            Estimated density (#/km\2\)
                                         -------------------------------
                 Species                   Intermediate
                                            water  100-     Deep water
                                              1,000 m        >1,000 m
------------------------------------------------------------------------
Sperm whale.............................         0.00384         0.00579
Atlantic spotted dolphin................         0.07022         0.00001
Beaked whale guild \a\..................         0.00498         0.00882
Common bottlenose dolphin...............         0.18043         0.00566
Clymene dolphin.........................         0.00325         0.00403
False killer whale......................         0.00744         0.00748
Frasers dolphin.........................         0.00386         0.00389
Killer whale............................         0.00007         0.00082
Melon-headed whale......................         0.00624         0.01186
Pantropical spotted dolphin.............         0.14764         0.31353
Short-finned pilot whales...............         0.00636         0.00128
Pygmy killer whale......................         0.00201         0.00648
Risso's dolphin.........................         0.02315         0.00748
Rough-toothed dolphin...................         0.00890         0.00768
Spinner dolphin.........................         0.15723         0.00412
Striped dolphin.........................         0.00212         0.01268
Kogia spp.\b\...........................         0.01052         0.00490
------------------------------------------------------------------------
\a\ Includes Cuvier's beaked whale, Blainville's beaked whale, and
  Gervais' beaked whale.
\b\ Pygmy sperm whales and dwarf sperm whales.

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate.
    The area expected to be ensonified was determined by entering the 
planned survey lines into ArcGIS and then using GIS to identify the 
relevant ensonified areas by ``drawing'' the 160-dB threshold buffer 
around each seismic line according to the depth category in which the 
lines occurred. The total ensonified area within each depth category 
was then divided by the total number of survey days to provide the 
proportional daily ensonified area within each depth category. The 
total ensonified area in each depth class was multiplied by 1.25 to add 
an additional 25 percent contingency to allow for additional airgun 
operations such as testing of the source or re-surveying lines with 
poor data quality. Due to uncertainties with respect to permitting for 
surveys in Cuban waters, ensonified areas were calculated separately 
for transect lines in Mexican and Cuban EEZs, for which 4.2 and 5.5 
survey days were estimated, respectively (Table 7). If Scripps is 
unable to operate within the Cuban EEZ, they will conduct the entire 
survey within the Mexican EEZ, with the same estimated daily 
proportions of survey activity in each depth strata occurring over a 
total of 9.7 survey days. This scenario yields a total ensonified area 
of 3,595.6 km\2\, with 1,848.6 km\2\ in intermediate waters (100-1,000 
m) and 1,747.0 km\2\ in deep waters (>1,000 m).

      Table 7--Areas (km\2\) in Mexican and Cuban EEZs to be Ensonified Above Level B Harassment Threshold
----------------------------------------------------------------------------------------------------------------
                                                    Ensonified                                      Total area
                                     Relevant         area in       Ensonified         Total         with 25%
      Water depth category         isopleth  (m)    Mexican EEZ   area in  Cuban    ensonified       increase
                                                      (km\2\)      EEZ  (km\2\)    area  (km\2\)      (km\2\)
----------------------------------------------------------------------------------------------------------------
Intermediate (100-1000 m).......             809          640.35               0          640.35          800.44
Deep (>1000)....................             539          605.14         1298.09         1903.23         2379.04
                                 -------------------------------------------------------------------------------
    Total.......................  ..............         1245.49         1298.09         2543.58         3179.48
----------------------------------------------------------------------------------------------------------------

    To estimate the total number of possible exposures, the total 
ensonified area within each depth category is multiplied by the 
densities in each depth category. Scripps does not expect to know 
whether surveying within Cuban waters will be permitted until 
immediately before the research cruise, therefore NMFS has authorized 
the highest calculated take number for each species across the two 
survey scenarios (Table 8).

[[Page 40194]]



                                              Table 8--Calculated and Authorized Takes by Level B Harassment, and Percentage of Population Exposed
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Mexico and      Mexico and
                                                                    Cuba lines      Cuba lines      Mexico only     Mexico only     Authorized      Authorized      Population      Percent of
                             Species                                calculated      calculated      calculated      calculated        level B         level A        size \a\       population
                                                                      level B         level A         level B         level A
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale.....................................................              17               0              17               0              17               0           2,207            0.78
Atlantic spotted dolphin........................................              56               0             130               0             130               0          74,785            0.17
Beaked whale guild \c\..........................................              25               0              25               0              25               0           3,768            0.66
Common bottlenose dolphin.......................................             158               0             343               0             343               0         176,108            0.20
Clymene dolphin.................................................          \b\ 90               0          \b\ 90               0          \b\ 90               0          11,895            0.76
False killer whale..............................................          \b\ 28               0          \b\ 28               0          \b\ 28               0           3,204            0.87
Frasers dolphin.................................................          \b\ 65               0          \b\ 65               0          \b\ 65               0           1,665            3.90
Killer whale....................................................           \b\ 7               0           \b\ 7               0           \b\ 7               0             267            2.62
Melon-headed whale..............................................         \b\ 100               0         \b\ 100               0         \b\ 100               0           7,003            1.43
Pantropical spotted dolphin.....................................             862               2             820               1             864               0         102,361            0.84
Pygmy killer whale..............................................          \b\ 19               0          \b\ 19               0          \b\ 19               0           2,126            0.89
Risso's dolphin.................................................              36               0              56               0              56               0           3,764            1.48
Rough-toothed dolphin...........................................          \b\ 56               0          \b\ 56               0          \b\ 56               0           4,853            1.15
Short-finned pilot whales.......................................          \b\ 25               0          \b\ 25               0          \b\ 25               0           1,981            1.26
Spinner dolphin.................................................             136               0             298               0             298               0          25,114            1.19
Striped dolphin.................................................          \b\ 46               0          \b\ 46               0          \b\ 46               0           5,229            0.88
Kogia spp.......................................................              19               1              27               1              28               0           4,373            0.64
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Best abundance estimate. For most taxa, the best abundance estimate for purposes of comparison with take estimates is considered here to be the model-predicted abundance (Roberts et al.,
  2016). For those taxa where a density surface model predicting abundance by month was produced, the maximum mean seasonal abundance was used. For those taxa where abundance is not predicted
  by month, only mean annual abundance is available. For the killer whale, the larger estimated SAR abundance estimate is used.
\b\ Calculated and authorized take increased to mean group size as presented by Maze-Foley and Mullin (2006).
\c\ Cuvier's, Blainville's, and Gervais' beaked whales.

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, we 
carefully consider 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, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    Scripps indicated that it reviewed mitigation measures employed 
during seismic research surveys authorized by NMFS under previous 
incidental harassment authorizations, as well as recommended best 
practices in Richardson et al. (1995), Pierson et al. (1998), Weir and 
Dolman (2007), Nowacek et al. (2013), Wright (2014), and Wright and 
Cosentino (2015), and has incorporated a suite of mitigation measures 
into their project description based on the above sources.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, Scripps will implement mitigation 
measures for marine mammals. Mitigation measures that must be adopted 
during the planned surveys include: (1) Vessel-based visual mitigation 
monitoring; (2) Establishment of a marine mammal exclusion zone (EZ) 
and buffer zone; (3) shutdown procedures; (4) ramp-up procedures; and 
(4) vessel strike avoidance measures.

Vessel-Based Visual 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. PSO 
observations must take place during all daytime airgun operations and 
nighttime start ups (if applicable) of the airguns. If airguns are 
operating throughout the night, observations must begin 30 minutes 
prior to sunrise. If airguns are operating after sunset, observations 
must continue until 30 minutes following sunset. Following a shutdown 
for any reason, observations must occur for at least 30 minutes prior 
to the planned start of airgun operations. Observations must also occur 
for 30 minutes after airgun operations cease for any reason. 
Observations must also be made during daytime periods when the R/V 
Justo Sierra is underway without seismic operations, such as during 
transits, to allow for comparison of sighting rates and behavior with 
and without airgun operations and between acquisition periods. Airgun 
operations must be suspended when marine mammals are observed within, 
or about to enter, the designated exclusion zone (EZ) (as described 
below).
    During seismic operations, two visual PSOs must be on duty and 
conduct visual observations at all times during daylight hours (i.e., 
from 30 minutes prior to sunrise through 30 minutes following sunset). 
PSO(s) must be on duty in shifts of duration no longer than

[[Page 40195]]

4 hours. Other vessel crew must also be instructed to assist in 
detecting marine mammals and in implementing mitigation requirements 
(if practical). Before the start of the seismic survey, the crew must 
be given additional instruction in detecting marine mammals and 
implementing mitigation requirements.
    The R/V Justo Sierra is a suitable platform from which PSOs would 
watch for marine mammals. Standard equipment for marine mammal 
observers must be 7 x 50 reticule binoculars and optical range finders. 
At night, night-vision equipment must be available. The observers must 
be in communication with ship's officers on the bridge and scientists 
in the vessel's operations laboratory, so they can advise promptly of 
the need for vessel strike avoidance measures (see Vessel Strike 
Avoidance Measures below) or seismic source shutdown.
    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 must be provided to NMFS for 
approval. At least one PSO must have a minimum of 90 days prior at-sea 
experience working as a PSO during a seismic survey. One 
``experienced'' visual PSO will be designated as the lead for the 
entire protected species observation team. The lead will serve as 
primary point of contact for the vessel operator.

Exclusion Zone (EZ) and Buffer Zone

    An EZ is a defined area within which occurrence of a marine mammal 
triggers mitigation action intended to reduce the potential for certain 
outcomes, e.g., auditory injury, disruption of critical behaviors. The 
PSOs must establish a minimum EZ with a 100 m radius for the airgun 
array. The 100-m EZ must be based on radial distance from any element 
of the airgun array (rather than being based around the vessel itself). 
With certain exceptions (described below), if a marine mammal appears 
within, enters, or appears on a course to enter this zone, the acoustic 
source must be shut down (see Shutdown Procedures below).
    The 100-m radial distance of the standard EZ is precautionary in 
the sense that it would be expected to contain sound exceeding injury 
criteria for all marine mammal hearing groups (Table 5) while also 
providing a consistent, reasonably observable zone within which PSOs 
would typically be able to conduct effective observational effort. In 
the 2011 Programmatic Environmental Impact Statement for marine 
scientific research funded by the National Science Foundation or the 
U.S. Geological Survey (NSF-USGS 2011), Alternative B (the Preferred 
Alternative) conservatively applied a 100-m EZ for all low-energy 
acoustic sources in water depths >100 m, with low-energy acoustic 
sources defined as any towed acoustic source with a single or a pair of 
clustered airguns with individual volumes of <=250 in\3\. Thus the 100-
m EZ required for this survey is consistent with the PEIS.
    Our intent in prescribing a standard EZ distance is to (1) 
encompass zones within which auditory injury could occur on the basis 
of instantaneous exposure; (2) provide additional protection from the 
potential for more severe behavioral reactions (e.g., panic, 
antipredator response) for marine mammals at relatively close range to 
the acoustic source; (3) provide consistency for PSOs, who need to 
monitor and implement the EZ; and (4) define a distance within which 
detection probabilities are reasonably high for most species under 
typical conditions.
    PSOs must also establish and monitor a 100-m buffer zone beyond the 
EZ (for a total of 200 m). During use of the acoustic source, 
occurrence of marine mammals within the buffer zone (but outside the 
EZ) must be communicated to the operator to prepare for potential 
shutdown of the acoustic source. The buffer zone is discussed further 
under Ramp-Up Procedures below.
    An extended EZ of 500 m must be established for all beaked whales 
and Kogia species as well as for aggregations of six or more large 
whales (i.e., sperm whale) or a large whale with a calf (calf defined 
as an animal less than two-thirds the body size of an adult observed to 
be in close association with an adult).

Ramp-Up Procedures

    Ramp-up of an acoustic source is intended to provide a gradual 
increase in sound levels following a shutdown, enabling animals to move 
away from the source if the signal is sufficiently aversive prior to 
its reaching full intensity. Ramp-up is required after the array is 
shut down for any reason for longer than 15 minutes. Ramp-up must begin 
with the activation of one 45 in\3\ airgun, with the second 45 in\3\ 
airgun activated after 5 minutes.
    Two PSOs are required to monitor during ramp-up. During ramp up, 
the PSOs must monitor the EZ, and if marine mammals were observed 
within the EZ or buffer zone, a shutdown must be implemented as though 
the full array were operational. If airguns have been shut down due to 
PSO detection of a marine mammal within or approaching the EZ, ramp-up 
must not be initiated until all marine mammals have cleared the EZ, 
during the day or night. Criteria for clearing the EZ would be as 
described above.
    Thirty minutes of pre-start clearance observation are required 
prior to ramp-up for any shutdown of longer than 30 minutes (i.e., when 
the array is shut down during transit from one line to another). This 
30-minute pre-start clearance period may occur during any vessel 
activity (i.e., transit). If a marine mammal is observed within or 
approaching the 200-m buffer or 500-m extended EZ during this pre-start 
clearance period, ramp-up must not be initiated until all marine 
mammals cleared the relevant area. Criteria for clearing the EZ would 
be as described above. If the airgun array has been shut down for 
reasons other than mitigation (e.g., mechanical difficulty) for a 
period of less than 30 minutes, it may be activated again without ramp-
up if PSOs have maintained constant visual observation and no 
detections of any marine mammal have occurred within the EZ or buffer 
zone. Ramp-up must be planned to occur during periods of good 
visibility when possible. However, ramp-up is allowed at night and 
during poor visibility if the 100 m EZ and 200 m buffer zone have been 
monitored by visual PSOs for 30 minutes prior to ramp-up.
    The operator is required to notify a designated PSO of the planned 
start of ramp-up as agreed-upon with the lead PSO; the notification 
time must not be less than 60 minutes prior to the planned ramp-up. A 
designated PSO must be notified again immediately prior to initiating 
ramp-up procedures and the operator must receive confirmation from the 
PSO to proceed. The operator must provide information to PSOs 
documenting that appropriate procedures were followed. Following 
deactivation of the array for reasons other than mitigation, the 
operator is required to communicate the near-term operational plan to 
the lead PSO with justification for any planned nighttime ramp-up.

Shutdown Procedures

    If a marine mammal is detected outside the EZ but is likely to 
enter the EZ, the airguns must be shut down before the animal is within 
the EZ. Likewise, if a marine mammal is already within the EZ when 
first detected, the airguns must be shut down immediately.
    Following a shutdown, airgun activity must not resume until the 
marine mammal has cleared the EZ. The animal

[[Page 40196]]

is considered to have cleared the EZ if the following conditions have 
been met:
    <bullet> it is visually observed to have departed the EZ;
    <bullet> it has not been seen within the EZ for 15 min in the case 
of small odontocetes; or
    <bullet> it has not been seen within the EZ for 30 min in the case 
of large odontocetes, including sperm and beaked whales.
    This shutdown requirement is in place for all marine mammals, with 
the exception of small delphinids under certain circumstances. As 
defined here, the small delphinid 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 would apply solely to specific genera of small dolphins--
Lagenodelphis, Stenella, Steno, and Tursiops.
    We include this small delphinid exception because shutdown 
requirements for small delphinids under all circumstances represent 
practicability concerns without likely commensurate benefits for the 
animals in question. Small delphinids 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 mid-frequency cetaceans (e.g., delphinids), as this group 
is relatively insensitive to sound produced at the predominant 
frequencies in an airgun pulse while also having a relatively high 
threshold for the onset of auditory injury (i.e., permanent threshold 
shift).
    A large body of anecdotal evidence indicates that small delphinids 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinids (e.g., Barkaszi et al., 2012, 2018). The potential 
for increased shutdowns resulting from such a measure would require the 
R/V Justo Sierra to revisit the missed track line to reacquire data, 
resulting in an overall increase in the total sound energy input to the 
marine environment and an increase in the total duration over which the 
survey is active in a given area. Although other mid-frequency hearing 
specialists (e.g., large delphinids) are no more likely to incur 
auditory injury than are small delphinids, they are much less likely to 
approach vessels. Therefore, retaining a shutdown requirement for large 
delphinids would not have similar impacts in terms of either 
practicability for the applicant or corollary increase in sound energy 
output and time on the water. We do anticipate some benefit for a 
shutdown requirement for large delphinids in that it simplifies 
somewhat the total range of decision-making for PSOs and may preclude 
any potential for physiological effects other than to the auditory 
system as well as some more severe behavioral reactions for any such 
animals in close proximity to the source vessel.
    Visual PSOs must use best professional judgment in making the 
decision to call for a shutdown if there is uncertainty regarding 
identification (i.e., whether the observed marine mammal(s) belongs to 
one of the delphinid genera for which shutdown is waived or one of the 
species with a larger EZ).
    Shutdown of the acoustic source is also required upon observation 
of a species for which authorization has not been granted (e.g., baleen 
whales), or a species for which authorization has been granted but the 
authorized number of takes are met, observed approaching or within the 
Level B harassment zones.

Vessel Strike Avoidance Measures

    Vessel strike avoidance measures are intended to minimize the 
potential for collisions with marine mammals. 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.
    The required measures include the following: Vessel operator and 
crew must maintain a vigilant watch for all marine mammals and slow 
down or stop the vessel or alter course to avoid striking any marine 
mammal. A visual observer aboard the vessel must monitor a vessel 
strike avoidance zone around the vessel according to the parameters 
stated below. Visual observers monitoring the vessel strike avoidance 
zone may be either third-party observers or crew members, but crew 
members responsible for these duties must be provided sufficient 
training to distinguish marine mammals from other phenomena. Vessel 
strike avoidance measures must be followed during surveys and while in 
transit.
    The vessel must maintain a minimum separation distance of 100 m 
from large whales (i.e., baleen whales and sperm whales). If a large 
whale is within 100 m of the vessel, the vessel must reduce speed and 
shift the engine to neutral, and must not engage the engines until the 
whale has moved outside of the vessel's path and the minimum separation 
distance has been established. If the vessel is stationary, the vessel 
must not engage engines until the whale(s) has moved out of the 
vessel's path and beyond 100 m. The vessel must maintain a minimum 
separation distance of 50 m from all other marine mammals, to the 
extent practicable. If an animal is encountered during transit, the 
vessel must attempt to remain parallel to the animal's course, avoiding 
excessive speed or abrupt changes in course. Vessel speeds must be 
reduced to 10 knots or less when mother/calf pairs, pods, or large 
assemblages of cetaceans are observed near the vessel.
    We have carefully evaluated the suite of mitigation measures 
described here and considered a range of other measures in the context 
of ensuring that we prescribe the means of effecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. Based on our evaluation of the required 
measures, NMFS has determined that the mitigation measures provide the 
means 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 in the 
planned survey area. 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:
    <bullet> Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density).
    <bullet> Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through

[[Page 40197]]

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 action; or (4) biological or behavioral context of 
exposure (e.g., age, calving or feeding areas).
    <bullet> Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors.
    <bullet> How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks.
    <bullet> Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat).
    <bullet> Mitigation and monitoring effectiveness.
    Monitoring that is designed specifically to facilitate mitigation 
measures, such as monitoring of the EZ to inform potential shutdowns of 
the airgun array, are described above and are not repeated here. The 
required monitoring and reporting includes the following:

Vessel-Based Visual Monitoring

    As described above, PSO observations must take place during daytime 
airgun operations and nighttime start-ups (if applicable) of the 
airguns. During seismic operations, visual PSOs must be based aboard 
the R/V Justo Sierra. PSOs must be appointed by Scripps with NMFS 
approval. The PSOs must have successfully completed relevant training, 
including completion of all required coursework and passing a written 
and/or oral examination developed for the training program, and must 
have successfully attained a bachelor's degree from an accredited 
college or university with a major in one of the natural sciences and 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 training, including (1) secondary 
education and/or experience comparable to PSO duties; (2) previous work 
experience conducting academic, commercial, or government-sponsored 
marine mammal surveys; or (3) previous work experience as a PSO; the 
PSO must demonstrate good standing and consistently good performance of 
PSO duties.
    During seismic operations in daylight hours (30 minutes before 
sunrise through 30 minutes after sunset), two PSOs must monitor for 
marine mammals around the seismic vessel. PSOs must be on duty in 
shifts of duration no longer than 4 hours. Other crew must also be 
instructed to assist in detecting marine mammals and in implementing 
mitigation requirements (if practical). During daytime, PSOs must scan 
the area around the vessel systematically with reticle binoculars 
(e.g., 7 x 50 Fujinon) and with the naked eye. At night, PSOs must be 
equipped with night-vision equipment.
    For data collection purposes, PSOs must use standardized data 
collection forms, whether hard copy or electronic. PSOs must record 
detailed information about any implementation of mitigation 
requirements, including the distance of animals to the acoustic source 
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 acoustic source. If 
required mitigation was not implemented, PSOs must record a description 
of the circumstances. At a minimum, the following information must be 
recorded:
    <bullet> Vessel names (source vessel and other vessels associated 
with survey) and call signs;
    <bullet> PSO names and affiliations;
    <bullet> Dates of departures and returns to port with port name;
    <bullet> Date and participants of PSO briefings;
    <bullet> Dates and times (Greenwich Mean Time) of survey effort and 
times corresponding with PSO effort;
    <bullet> Vessel location (latitude/longitude) when survey effort 
began and ended and vessel location at beginning and end of visual PSO 
duty shifts;
    <bullet> Vessel heading and speed at beginning and end of visual 
PSO duty shifts and upon any line change;
    <bullet> 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;
    <bullet> Factors that may have contributed to impaired observations 
during each PSO shift change or as needed as environmental conditions 
changed (e.g., vessel traffic, equipment malfunctions); and
    <bullet> Survey activity information, such as acoustic source 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-clearance, ramp-up, shutdown, testing, shooting, ramp-up 
completion, end of operations, streamers, etc.).
    The following information must be recorded upon visual observation 
of any protected species:
    <bullet> Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
    <bullet> PSO who sighted the animal;
    <bullet> Time of sighting;
    <bullet> Vessel location at time of sighting;
    <bullet> Water depth;
    <bullet> Direction of vessel's travel (compass direction);
    <bullet> Direction of animal's travel relative to the vessel;
    <bullet> Pace of the animal;
    <bullet> Estimated distance to the animal and its heading relative 
to vessel at initial sighting;
    <bullet> 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;
    <bullet> Estimated number of animals (high/low/best);
    <bullet> Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
    <bullet> 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);
    <bullet> 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);
    <bullet> Animal's closest point of approach (CPA) and/or closest 
distance from any element of the acoustic source;
    <bullet> Platform activity at time of sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other); and
    <bullet> Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up) and time and location of the 
action.

Reporting

    A report must be submitted to NMFS within 90 days after the end of 
the cruise. The report must describe the operations that were conducted 
and sightings of marine mammals near the operations. The report must 
provide full documentation of methods, results, and interpretation 
pertaining to all

[[Page 40198]]

monitoring. The 90-day report must summarize the dates and locations of 
seismic operations, and all marine mammal sightings (dates, times, 
locations, activities, associated seismic survey activities).
    The draft report must also include geo-referenced time-stamped 
vessel tracklines for all time periods during which airguns were 
operating. Tracklines must 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). GIS files must be provided in ESRI shapefile format and include 
the UTC date and time, latitude in decimal degrees, and longitude in 
decimal degrees. All coordinates must be referenced to the WGS84 
geographic coordinate system. In addition to the report, all raw 
observational data must be made available to NMFS. The report must 
summarize the data collected as described above and in the IHA. 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 survey activities covered by the authorization 
discover an injured or dead marine mammal, Scripps must report the 
incident to the Office of Protected Resources (OPR), NMFS and to the 
NMFS Southeast Regional Stranding Coordinator as soon as feasible. The 
report must include the following information:
    <bullet> Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    <bullet> Species identification (if known) or description of the 
animal(s) involved;
    <bullet> Condition of the animal(s) (including carcass condition if 
the animal is dead);
    <bullet> Observed behaviors of the animal(s), if alive;
    <bullet> If available, photographs or video footage of the 
animal(s); and
    <bullet> General circumstances under which the animal was 
discovered.
    Vessel strike--In the event of a ship strike of a marine mammal by 
any vessel involved in the activities covered by the authorization, 
Scripps must 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:
    <bullet> Time, date, and location (latitude/longitude) of the 
incident;
    <bullet> Vessel's speed during and leading up to the incident;
    <bullet> Vessel's course/heading and what operations were being 
conducted (if applicable);
    <bullet> Status of all sound sources in use;
    <bullet> 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;
    <bullet> Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
    <bullet> Species identification (if known) or description of the 
animal(s) involved;
    <bullet> Estimated size and length of the animal that was struck;
    <bullet> Description of the behavior of the animal immediately 
preceding and following the strike;
    <bullet> If available, description of the presence and behavior of 
any other marine mammals present immediately preceding the strike;
    <bullet> 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
    <bullet> 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 responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), 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's 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 environmental 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, our analysis applies to all species listed in 
Table 1, given that NMFS expects the anticipated effects of the planned 
geophysical survey to be similar in nature. Where there are meaningful 
differences between species or stocks, or groups of species, in 
anticipated individual responses to activities, impact of expected take 
on the population due to differences in population status, or impacts 
on habitat, NMFS has identified species-specific factors to inform the 
analysis.
    NMFS does not anticipate that injury, serious injury or mortality 
would occur as a result of Scripps' planned survey, even in the absence 
of mitigation, and none is authorized. Similarly, non-auditory physical 
effects, stranding, and vessel strike are not expected to occur. 
Although a few incidents of Level A harassment were predicted through 
the quantitative exposure estimation process (see Estimated Take), NMFS 
has determined that this is not a realistic result due to the small 
estimated Level A harassment zones for the species (no greater than 
approximately 50 m) and the mitigation requirements, and no take by 
Level A harassment has been authorized. These estimated zones are 
larger than what would realistically occur, as discussed in the 
Estimated Take section.
    We expect that takes would be in the form of short-term Level B 
behavioral harassment in the form of temporary avoidance of the area or 
decreased foraging (if such activity were occurring), reactions that 
are considered to be of low severity and with no lasting biological 
consequences (e.g., Southall et al., 2007, Ellison et al., 2012).
    Marine mammal habitat may be impacted by elevated sound levels, but 
these impacts would be temporary. Prey species are mobile and are 
broadly distributed throughout the project 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 
relatively short duration (up to 12 days) and temporary nature of the 
disturbance, the availability of similar habitat and resources in the 
surrounding area, the impacts to marine mammals and the food sources 
that they utilize

[[Page 40199]]

are not expected to cause significant or long-term consequences for 
individual marine mammals or their populations. No biologically 
important areas, designated critical habitat, or other habitat of known 
significance would be impacted by the planned activities.

Negligible Impact Conclusions

    The planned survey would be of short duration (up to 12 days of 
seismic operations), and the acoustic ``footprint'' of the survey would 
be small relative to the ranges of the marine mammals that would 
potentially be affected. Sound levels would increase in the marine 
environment in a relatively small area surrounding the vessel compared 
to the range of the marine mammals within the survey area. Short-term 
exposures to survey operations are expected to only temporarily affect 
marine mammal behavior in the form of avoidance, and the potential for 
longer-term avoidance of important areas is limited. Short-term 
exposures to survey operations are not likely to impact marine mammal 
behavior, and the potential for longer-term avoidance of important 
areas is limited.
    The required mitigation measures are expected to reduce the number 
and/or severity of takes by allowing for detection of marine mammals in 
the vicinity of the vessel by visual observers, and by minimizing the 
severity of any potential exposures via shutdowns of the airgun array.
    NMFS concludes that exposures to marine mammal species and stocks 
due to Scripps' planned survey would result in only short-term 
(temporary and short in duration) effects to individuals exposed, over 
relatively small areas of the affected animals' ranges. Animals may 
temporarily avoid the immediate area, but are not expected to 
permanently abandon the area. Major shifts in habitat use, 
distribution, or foraging success are not expected. NMFS does not 
anticipate the authorized take to impact annual rates of recruitment or 
survival.
    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:
    <bullet> No Level A harassment, serious injury or mortality is 
anticipated or authorized;
    <bullet> The planned activity is temporary and of relatively short 
duration (up to 12 days);
    <bullet> The anticipated impacts of the planned activity on marine 
mammals would primarily be temporary behavioral changes in the form of 
avoidance of the area around the survey vessel;
    <bullet> 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;
    <bullet> The potential adverse effects on fish or invertebrate 
species that serve as prey species for marine mammals from the planned 
survey would be temporary and spatially limited, and impacts to marine 
mammal foraging would be minimal; and
    <bullet> The required mitigation measures, including visual 
monitoring, shutdowns, ramp-up, and prescribed measures based on energy 
size are expected to minimize potential impacts to marine mammals (both 
amount and severity).
    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 required monitoring and 
mitigation measures, NMFS finds that the total marine mammal take from 
Scripps' activity will have a negligible impact on all affected marine 
mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    The amount of take NMFS has authorized is below one third of the 
estimated population abundance of all species (Roberts et al., 2016). 
In fact, take of individuals is less than 4 percent of the abundance of 
the affected populations (see Table 8).
    Based on the analysis contained herein of the planned activity 
(including the required mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS finds that small numbers of 
marine mammals will 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.

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 
incidental harassment authorization) with respect to potential impacts 
on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (incidental harassment authorizations 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.

Endangered Species Act

    Section 7(a)(2) of the Endangered Species Act of 1973 (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 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, in this case with the ESA Interagency 
Cooperation Division.
    The NMFS Office of Protected Resources Interagency Cooperation 
Division issued a Biological Opinion under section 7 of the ESA, on the 
issuance of an IHA to Scripps under section 101(a)(5)(D) of the MMPA by 
the NMFS Office of Protected Resources

[[Page 40200]]

Permits and Conservation Division. The Biological Opinion concluded 
that the proposed action is not likely to jeopardize the continued 
existence of any listed marine mammal species.

Authorization

    As a result of these determinations, NMFS has issued an IHA to 
Scripps for conducting geophysical surveys in the southeast Gulf of 
Mexico in summer 2022, provided the previously mentioned mitigation, 
monitoring, and reporting requirements are incorporated.

    Dated: June 30, 2022.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2022-14362 Filed 7-5-22; 8:45 am]
BILLING CODE 3510-22-P