`[Federal Register Volume 88, Number 197 (Friday, October 13, 2023)]
[Notices]
[Pages 70938-70954]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-22632]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD403]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Marine Geophysical Survey of 
Puerto Rico in the Northwest Atlantic Ocean

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

ACTION: Notice; issuance of an incidental harassment authorization.

-----------------------------------------------------------------------

SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that NMFS has issued an incidental harassment authorization (IHA) to 
Lamont-Doherty Earth Observatory (L-DEO) to incidentally harass marine 
mammals during a marine geophysical survey near Puerto Rico in the 
northwest Atlantic Ocean.

DATES: This authorization is effective from October 6, 2023 through 
October 5, 2024.

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

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

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are proposed or, if the taking is limited to harassment, a notice of a 
proposed IHA is provided to the public for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the 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 April 27, 2023, NMFS received a request from L-DEO for an IHA to 
take marine mammals incidental to a marine geophysical survey of the 
Puerto Rico Trench and the southern slope of Puerto Rico in the 
northwest Atlantic Ocean. L-DEO submitted a revised application on July 
27, 2023. The application was deemed adequate and complete on July 27, 
2023. L-DEO's request is for take of 27 marine mammal species by Level 
B harassment, and for a subset of 5 of these species, by Level A 
harassment. Neither L-DEO nor NMFS expect serious injury or mortality 
to result from this activity and, therefore, an IHA is appropriate. 
There are no changes from the proposed IHA to the final IHA.

Description of Activity

Overview

    Researchers from the Woods Hole Oceanographic Institution (WHOI), 
University of Texas Institute of Geophysics (UTIG), and University of 
Puerto Rico Mayaguez (UPRM), with funding from the U.S. National 
Science Foundation (NSF) and in collaboration with the United States 
Geological Survey (USGS) and researchers from the GEOMAR Helmholtz 
Centre for Ocean Research (GEOMAR), plan to conduct research, including 
seismic surveys using airguns as the acoustic source, from the research 
vessel R/V Marcus G. Langseth (Langseth). The surveys, including high 
and low energy surveys, would occur in the Puerto Rico Trench and the 
southern slope of Puerto Rico in the northwestern Atlantic Ocean during 
fall 2023. The survey would occur within the U.S. Exclusive Economic 
Zone (EEZ) around Puerto Rico and the U.S. Virgin Islands and within 
the

[[Page 70939]]

coastal zone of Puerto Rico, and within the EEZs of the Dominican 
Republic and the British Virgin Islands. The survey would occur in 
water depths ranging from approximately 1,000 to 8,400 meters (m) for 
the high energy survey portion and approximately 100 to 3,000 m for the 
low energy survey portion.
    To complete this survey, the R/V Langseth would tow two different 
airgun configurations: (a) 36-airgun towed array with a total discharge 
volume of ~6600 cubic inches (in\3\) at a depth of 12 m for the high-
energy surveys, and (b) two 45/105-in\3\ generator-injector (GI) 
airguns with a total discharge volume of 90 in\3\ off southern Puerto 
Rico at a depth of 3 m for the low-energy surveys. The airgun array 
receiving systems for the different survey segments would consist of a 
15 kilometer (km) long solid-state hydrophone streamer, approximately 
31 short-period Ocean Bottom Seismometers (OBS), and 10 ultra-deep-
water broadband OBS for the high-energy portion, and 150 m solid-state 
hydrophone streamer for the low-energy portion. For the high-energy 
survey, the airguns would fire at a shot interval of 50 m (~24 seconds 
(s)) during multi-channel seismic (MCS) reflection surveys with the 
hydrophone streamer and at a 400-m (~155 s) interval during OBS seismic 
refraction surveys. For the low energy survey, the airgun would fire at 
a shot interval of 6.25 m (2.7 s). Approximately 4,630 km of total 
survey trackline are planned.
    The purpose of the high-energy survey is to investigate the Puerto 
Rico Trench, its outer rise, and across the island of Puerto Rico, and 
provide data necessary to illuminate the depth, geometry, and physical 
properties of the seismogenic fault interface between the subducting 
Atlantic plate and the overlying accretionary wedge/Puerto Rico arc/
Caribbean plate, as well as seismogenic structures in the accretionary 
wedge and submarine slopes of the island of Puerto Rico. The low-energy 
seismic surveys would be located over a 2019-2020 area of seismic 
activity in the Caribbean Sea to define the geometry of the faults that 
ruptured and other potential seismogenic structures. Additional data 
would be collected using a multibeam echosounder (MBES), a sub-bottom 
profiler (SBP), and an Acoustic Doppler Current Profiler (ADCP), which 
would be operated from R/V Langseth continuously during the seismic 
surveys, including during transit. No take of marine mammals is 
expected to result from use of this equipment.

Dates and Duration

    The high-energy survey is expected to last for approximately 42 
days, with 21 days of seismic operations, 20 days for equipment 
deployment/recovery, and 2 days transit/contingency time. The low-
energy survey would consist of approximately 3 days of seismic 
operations. R/V Langseth would likely leave from and return to port in 
San Juan, Puerto Rico during fall 2023.

Specific Geographic Region

    The survey would occur within approximately 17-21[deg] N, 63.6-
68.2[deg] W, within the EEZs of Puerto Rico, U.S. Virgin Islands, 
British Virgin Islands, and the Dominican Republic, in water depths 
ranging from approximately 100-8400 m. The closest approach of the low-
energy survey lines to land on the south side of Puerto Rico is ~2.5 km 
from Isla de Ratones (Isla Pi[ntilde]ero), ~3.4 km from Cayo Maria 
Langa, and ~3 km from Cayo Aurora. The closest approach of the high-
energy survey lines to the coast of Puerto Rico is ~22 km, 28 km to the 
British Virgin Islands, 42 km to Dominican Republic, and 77 km to the 
U.S. Virgin Islands. The region where the survey is planned to occur is 
depicted in Figure 1; the tracklines could occur anywhere within the 
polygon shown in Figure 1. Representative survey tracklines are shown, 
however, some deviation in actual tracklines, including the order of 
survey operations, could be necessary for reasons such as science 
drivers, poor data quality, inclement weather, or mechanical issues 
with the research vessel and/or equipment.
BILLING CODE 3510-22-P

[[Page 70940]]

[GRAPHIC] [TIFF OMITTED] TN13OC23.079

BILLING CODE 3510-22-C
    A detailed description of the planned geophysical survey was 
provided in the Federal Register notice of the proposed IHA (88 FR 
56964; August 21, 2023). Since that time, no changes have been made to 
the planned survey activities. Therefore, a detailed description is not 
provided here. Please refer to that Federal Register notice for the 
description of the specified activity.

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to L-DEO was published 
in the Federal Register on August 21, 2023 (88 FR 56964). That notice 
described, in detail, L-DEO's activities, the marine mammal species 
that may be affected by the activities, and the anticipated effects on 
marine mammals. In that notice, we requested public input on the 
request for authorization described therein, our analyses, the proposed 
authorization, and any other aspect of the notice of proposed IHA, and 
requested that interested persons submit relevant information, 
suggestions, and comments. The proposed notice was available for a 30-
day public comment period. NMFS received no public comments.

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, instead of reprinting the information. Additional 
information regarding population trends and threats may be found in 
NMFS' Stock Assessment Reports (SARs; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more 
general information about these species (e.g., physical and behavioral 
descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species). NMFS refers the reader to the 
application and to the aforementioned sources for general information 
regarding the species listed in table 1.
    Table 1 lists all species or stocks for which take is expected and 
authorized for this activity, and summarizes information related to the 
population or stock, including regulatory status under the MMPA and 
Endangered Species Act (ESA) and potential biological removal (PBR), 
where known. PBR is defined by the MMPA as the maximum number of 
animals, not including natural mortalities, that may be removed from a 
marine mammal stock while allowing that stock to reach or maintain its

[[Page 70941]]

optimum sustainable population (as described in NMFS' SARs). While no 
serious injury or mortality is anticipated or authorized here, PBR and 
annual serious injury and mortality from anthropogenic sources are 
included here as gross indicators of the status of the species or 
stocks and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Atlantic and Gulf of Mexico SARs. All values presented in 
table 1 are the most recent available at the time of publication and 
are available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.
    Aside from the few species with stocks assigned for Puerto Rico and 
the U.S. Virgin Islands, individuals from the species affected would 
not be from the stocks described in the SARs. These stocks are not 
extensively studied but are provisionally being considered separate 
stocks for management purposes and further work to differentiate them 
from stocks in the Atlantic and Gulf of Mexico are being conducted. 
However, these stocks are likely trans-boundary within, at minimum, 
waters near adjacent Caribbean Islands and are not likely to occur 
exclusively within the bounds of the U.S. EEZ.

                          Table 1--Species Likely Impacted by the Specified Activities
----------------------------------------------------------------------------------------------------------------
                                                                                 Stock abundance
                                                                    ESA/ MMPA    (CV, Nmin, most
         Common name            Scientific name        Stock         status;    recent abundance      Modeled
                                                                    strategic      survey) \2\     abundance \3\
                                                                    (Y/N) \1\
----------------------------------------------------------------------------------------------------------------
                      Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
Family Balaenopteridae
 (rorquals):
    Humpback whale...........  Megaptera         ................  -/-; N       1,396 (0; 1,380;           4,990
                                novaeangliae.                                    2016).
    Fin whale................  Balaenoptera      ................  E/D; Y       6,802 (0.24;              11,672
                                physalus.                                        5,573; 2016).
    Sei whale................  Balaenoptera      ................  E/D; Y       6,292 (1.02;              19,530
                                borealis.                                        3,098; 2016).
    Minke whale..............  Balaenoptera      ................  -/-; N       21,968 (0.31;             13,784
                                acutorostrata.                                   17,002; 2016).
    Blue whale...............  Balaenoptera      ................  E/D;Y        unk (unk; 402;               191
                                musculus.                                        1980-2008).
----------------------------------------------------------------------------------------------------------------
                        Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale..............  Physeter          Puerto Rico and   E/D;Y        4,349 (0.28;              64,015
                                macrocephalus.    U.S. Virgin                    3,451; 2016)
                                                  Islands.                       \4\.
Family Kogiidae:
    Pygmy sperm whale........  Kogia breviceps.  ................  -/-; N       7,750 (0.38;              26,043
                                                                                 5,689; 2016).
    Dwarf sperm whale........  Kogia sima......  ................  -/-; N
Family Ziphiidae (beaked
 whales):
    Cuvier's beaked Whale....  Ziphius           Puerto Rico and   -/-; Y       5,744 (0.36,              65,069
                                cavirostris.      U.S. Virgin                    4,282, 2016)
                                                  Islands.                       \4\.
    Blainville's beaked Whale  Mesoplodon        ................  -/-; N       10,107 (0.27;     ..............
                                densirostris.                                    8,085; 2016).
    True's beaked whale......  Mesoplodon mirus  ................  -/-; N
    Gervais' beaked whale....  Mesoplodon        ................  -/-; N
                                europaeus.
Family Delphinidae:
    Short finned pilot whale.  Globicephala      Puerto Rico and   -/-;Y        28,924 (0.24;            264,907
                                macrorhynchus.    U.S. Virgin                    23,637; 2016)
                                                  Islands.                       \4\.
    Rough-toothed dolphin....  Steno             ................  -/-; N       136 (1.0; 67;             32,848
                                bredanensis.                                     2016).
    Bottlenose dolphin.......  Tursiops          Puerto Rico and   -/-; Y       62,851 (0.23;            418,151
                                truncatus.        U.S. Virgin                    51,914, 2016)
                                                  Islands.                       \4\.
    Pantropical spotted        Stenella          ................  -/-; N       6,593 (0.52;             321,740
     dolphin.                   attenuata.                                       4,367; 2016).
    Atlantic spotted dolphin.  Stenella          Puerto Rico and   -/-; Y       39,921 (0.27;            259,519
                                frontalis.        U.S. Virgin                    32,032; 2016)
                                                  Islands.                       \4\.
    Spinner dolphin..........  Stenella          Puerto Rico and   -/-; Y       4,102 (0.99;             152,511
                                longirostris.     U.S. Virgin                    2,045; 2016)
                                                  Islands.                       \4\.
    Clymene dolphin..........  Stenella clymene  ................  -/-; N       4,237 (1.03;             181,209
                                                                                 2,071; 2016).
    Striped dolphin..........  Stenella          ................  -/-; N       67,036 (0.29;            412,729
                                coeruleoalba.                                    52,939; 2016).
    Fraser's dolphin.........  Lagenodelphis     ................  -/-; N       unk.............          19,585
                                hosei.
    Risso's dolphin..........  Grampus griseus.  ................  -/-; N       35,215(0.19;              78,205
                                                                                 30,051; 2016).
    Common dolphin...........  Delphinus         ................  -/-; N       172,947 (0.21;           473,260
                                delphis.                                         145,216; 2016).
    Melon-headed whale.......  Peponocephala     ................  -/-; N       unk.............          64,114
                                electra.
    Pygmy killer whale.......  Feresa attenuate  ................  -/-; N       unk.............           9,001
    False killer whale.......  Pseudorca         ................  -/-; N       1,791 (0.56;              12,682
                                crassidens.                                      1,154; 2016).
    Killer whale.............  Orcinus orca....  ................  -/-; N       unk.............             972
----------------------------------------------------------------------------------------------------------------
\1\ 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/marine-mammal-stock-assessment-reports-region/. CV is coefficient of variation; Nmin is the minimum
  estimate of stock abundance; unknown (unk).
\3\ Modeled abundance value from U.S Navy Atlantic Fleet Training and Testing Area Marine Mammal Density (AFTT)
  (Roberts et al., 2023; Mannocci et al., 2017).
\4\ Puerto Rico and U.S. Virgin Islands stocks have unknown abundance, therefore providing abundance information
  associated with the Atlantic stocks as point of reference.


[[Page 70942]]

    As indicated above, all 27 species in table 1 temporally and 
spatially co-occur with the activity to the degree that take is 
reasonably likely to occur. Species that could potentially occur in the 
research area but are not likely to be harassed due to the rarity of 
their occurrence (i.e. are considered extralimital or rare visitors to 
the waters of the northwest Atlantic Ocean), or because their known 
migration through the area does not align with the survey dates, were 
omitted.
    A detailed description of the of the species likely to be affected 
by the geophysical survey, including brief introductions to the species 
and relevant stocks as well as available information regarding 
population trends and threats, and information regarding local 
occurrence, were provided in the Federal Register notice for the 
proposed IHA (88 FR 56964; August 21, 2023). Since that time, we are 
not aware of any changes in the status of these species and stocks; 
therefore, detailed descriptions are not provided here. Please refer to 
that Federal Register notice for these descriptions. Please also refer 
to NMFS' website (https://www.fisheries.noaa.gov/find-species) for 
generalized species accounts.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and 
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. 
(2007, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in table 2.

                  Table 2--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
               Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen        7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans (dolphins,     150 Hz to 160 kHz.
 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) (true    50 Hz to 86 kHz.
 seals).
Otariid pinnipeds (OW) (underwater) (sea    60 Hz to 39 kHz.
 lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

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

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effects of underwater noise from L-DEO's survey activities have 
the potential to result in harassment of marine mammals in the vicinity 
of the survey area. The notice of proposed IHA (88 FR 56964; August 21, 
2023) included a discussion of the effects of anthropogenic noise on 
marine mammals and the potential effects of underwater noise from L-DEO 
on marine mammals and their habitat. That information and analysis is 
not repeated here; please refer to the notice of proposed IHA (88 FR 
56964; August 21, 2023).

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
authorized through the IHA, which will inform both NMFS' consideration 
of ``small numbers,'' and the negligible impact determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be Level B harassment, as use of 
the airgun arrays have the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for auditory injury (Level A harassment) to result for 
species of certain hearing groups due to the size of the predicted 
auditory injury zones for those groups. Auditory injury is less likely 
to occur for mid-frequency species, due to their relative lack of 
sensitivity to the frequencies at which the primary energy of an airgun 
signal is found, as well as such species' general lower sensitivity to 
auditory injury as compared to high-frequency cetaceans. As discussed 
in further detail below, we do not expect auditory injury for mid-
frequency cetaceans. The mitigation and monitoring measures are 
expected to minimize the severity of such taking to the extent 
practicable. No mortality is anticipated as a result of

[[Page 70943]]

these activities. Below we describe how the take numbers are estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic thresholds above which NMFS believes the best 
available science indicates marine mammals will be behaviorally 
harassed or incur some degree of permanent hearing impairment; (2) the 
area or volume of water that will be ensonified above these levels in a 
day; (3) the density or occurrence of marine mammals within these 
ensonified areas; and, (4) the number of days of activities. We note 
that while these factors can contribute to a basic calculation to 
provide an initial prediction of potential takes, additional 
information that can qualitatively inform take estimates is also 
sometimes available (e.g., previous monitoring results or average group 
size). Below, we describe the factors considered here in more detail 
and present the take estimates.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur Permanent Threshold Shift (PTS) of some 
degree (equated to Level A harassment).
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced 
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile 
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g., 
scientific sonar) sources. Generally speaking, Level B harassment take 
estimates based on these behavioral harassment thresholds are expected 
to include any likely takes by Temporary Threshold Shift (TTS) as, in 
most cases, the likelihood of TTS occurs at distances from the source 
less than those at which behavioral harassment is likely. TTS of a 
sufficient degree can manifest as behavioral harassment, as reduced 
hearing sensitivity and the potential reduced opportunities to detect 
important signals (conspecific communication, predators, prey) may 
result in changes in behavior patterns that would not otherwise occur.
    L-DEO's survey includes the use of impulsive seismic sources (i.e., 
airguns), and therefore the 160 dB re 1 [mu]Pa is applicable for 
analysis of Level B harassment.
    Level A Harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). L-DEO's 
survey includes the use of impulsive seismic sources (e.g., airguns).
    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: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

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

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    When the Technical Guidance was published (NMFS, 2016), in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a user spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or

[[Page 70944]]

occurrence to help predict takes. We note that because of some of the 
assumptions included in the methods used for these tools, we anticipate 
that isopleths produced are typically going to be overestimates of some 
degree, which may result in some degree of overestimate of Level A 
harassment take. However, these tools offer the best way to predict 
appropriate isopleths when more sophisticated 3D modeling methods are 
not available, and NMFS continues to develop ways to quantitatively 
refine these tools, and will qualitatively address the output where 
appropriate.
    The survey would entail the use of a 36-airgun array with a total 
discharge volume of 6,600 in\3\ at a tow depth of 12 m and two 45/105 
in\3\ GI airguns at a tow depth of 3 m. L-DEO's model results are used 
to determine the 160 dBrms radius for both the airgun 
sources down to a maximum depth of 2,000 m. Received sound levels have 
been predicted by L-DEO's model (Diebold et al. 2010) as a function of 
distance from the 36-airgun array. This modeling approach uses ray 
tracing for the direct wave traveling from the array to the receiver 
and its associated source ghost (reflection at the air-water interface 
in the vicinity of the array), in a constant-velocity half-space 
(infinite homogeneous ocean layer, unbounded by a seafloor). In 
addition, propagation measurements of pulses from the 36-airgun array 
at a tow depth of 6 m have been reported in deep water (~1,600 m), 
intermediate water depth on the slope (~600-1,100 m), and shallow water 
(~50 m) in the Gulf of Mexico (Tolstoy et al. 2009; Diebold et al. 
2010).
    For deep and intermediate water cases, the field measurements 
cannot be used readily to derive the harassment isopleths, as at those 
sites the calibration hydrophone was located at a roughly constant 
depth of 350-550 m, which may not intersect all the SPL isopleths at 
their widest point from the sea surface down to the assumed maximum 
relevant water depth (~2,000 m) for marine mammals. At short ranges, 
where the direct arrivals dominate and the effects of seafloor 
interactions are minimal, the data at the deep sites are suitable for 
comparison with modeled levels at the depth of the calibration 
hydrophone. At longer ranges, the comparison with the model--
constructed from the maximum SPL through the entire water column at 
varying distances from the airgun array--is the most relevant.
    In deep and intermediate water depths at short ranges, sound levels 
for direct arrivals recorded by the calibration hydrophone and L-DEO 
model results for the same array tow depth are in good alignment (see 
Figures 12 and 14 in Diebold et al. 2010). Consequently, isopleths 
falling within this domain can be predicted reliably by the L-DEO 
model, although they may be imperfectly sampled by measurements 
recorded at a single depth. At greater distances, the calibration data 
show that seafloor-reflected and sub-seafloor-refracted arrivals 
dominate, whereas the direct arrivals become weak and/or incoherent 
(see Figures 11, 12, and 16 in Diebold et al. 2010). Aside from local 
topography effects, the region around the critical distance is where 
the observed levels rise closest to the model curve. However, the 
observed sound levels are found to fall almost entirely below the model 
curve. Thus, analysis of the Gulf of Mexico calibration measurements 
demonstrates that although simple, the L-DEO model is a robust tool for 
conservatively estimating isopleths.
    The high-energy survey would acquire data with the 36-airgun array 
at a tow depth of 12 m and the low-energy surveys would use two GI 
airguns at a 3m tow depth. For deep water (>1,000 m), we use the deep-
water radii obtained from L-DEO model results down to a maximum water 
depth of 2,000 m for the 36-airgun array and the two GI airguns. 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 Diebold et al. 2010).
    L-DEO's modeling methodology is described in greater detail in L-
DEO's application. The estimated distances to the Level B harassment 
isopleth for the airgun configuration are shown in table 4.

  Table 4--Predicted Radial Distances From the R/V Langseth Seismic Source to Isopleth Corresponding to Level B
                                              Harassment Threshold
----------------------------------------------------------------------------------------------------------------
                                                                                             Predicted distances
                                                                              Water depth    (in m) to the Level
                   Airgun configuration                      Tow depth (m)        (m)           B harassment
                                                                                                  threshold
----------------------------------------------------------------------------------------------------------------
4 strings, 36 airguns, 6,600 in\3\........................              12          >1,000             \1\ 6,733
Two 45/105 in GI airguns..................................               3          >1,000               \1\ 438
                                                                                 100-1,000               \2\ 657
----------------------------------------------------------------------------------------------------------------
\1\ Distance is based on L-DEO model results.
\2\ Distance is based on L-DEO model results with a 1.5 x correction factor between deep and intermediate water
  depths.


          Table 5--Modeled Radial Distance to Isopleths Corresponding to Level A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                                                   Low frequency   Mid frequency  High frequency
----------------------------------------------------------------------------------------------------------------
                                                   MCS Surveys
----------------------------------------------------------------------------------------------------------------
PTS SELcum......................................................           320.2               0               1
PTS Peak........................................................            38.9            13.6           268.3
----------------------------------------------------------------------------------------------------------------
The largest distance (in bold) of the dual criteria (SELcum or Peak) was used to estimate threshold distances
  and potential takes by Level A harassment.

    Table 5 presents the modeled PTS isopleths for each cetacean 
hearing group based on L-DEO modeling incorporated in the companion 
user spreadsheet, for the high-energy surveys with the shortest shot 
interval (i.e.,

[[Page 70945]]

greatest potential to cause PTS based on accumulated sound energy) 
(NMFS 2018).
    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal hearing groups, were calculated based on 
modeling performed by L-DEO using the Nucleus software program and the 
NMFS user spreadsheet, described below. The acoustic thresholds for 
impulsive sounds (e.g., airguns) contained in the NMFS Technical 
Guidance were presented as dual metric acoustic thresholds using both 
cumulative Sound Exposure Level (SELcum) and peak sound 
pressure metrics (NMFS 2016). As dual metrics, NMFS considers onset of 
PTS (Level A harassment) to have occurred when either one of the two 
metrics is exceeded (i.e., metric resulting in the largest isopleth). 
The SELcum metric considers both level and duration of 
exposure, as well as auditory weighting functions by marine mammal 
hearing group.
    The SELcum for the 36-airgun array is derived from 
calculating the modified farfield signature. The farfield signature is 
often used as a theoretical representation of the source level. To 
compute the farfield signature, the source level is estimated at a 
large distance (right) below the array (e.g., 9 km), and this level is 
back projected mathematically to a notional distance of 1 m from the 
array's geometrical center. However, it has been recognized that the 
source level from the theoretical farfield signature is never 
physically achieved at the source when the source is an array of 
multiple airguns separated in space (Tolstoy et al., 2009). Near the 
source (at short ranges, distances <1 km), the pulses of sound pressure 
from each individual airgun in the source array do not stack 
constructively as they do for the theoretical farfield signature. The 
pulses from the different airguns spread out in time such that the 
source levels observed or modeled are the result of the summation of 
pulses from a few airguns, not the full array (Tolstoy et al., 2009). 
At larger distances, away from the source array center, sound pressure 
of all the airguns in the array stack coherently, but not within one 
time sample, resulting in smaller source levels (a few dB) than the 
source level derived from the far-field signature. Because the far-
field signature does not take into account the large array effect near 
the source and is calculated as a point source, the far-field signature 
is not an appropriate measure of the sound source level for large 
arrays. See L-DEO's application for further detail on acoustic 
modeling.
    Auditory injury is unlikely to occur for mid-frequency cetaceans, 
given very small modeled zones of injury for those species (all 
estimated zones less than 15 m for mid-frequency cetaceans), in context 
of distributed source dynamics.
    In consideration of the received sound levels in the near-field as 
described above, we expect the potential for Level A harassment of mid-
frequency cetaceans to be de minimis, even before the likely moderating 
effects of aversion and/or other compensatory behaviors (e.g., 
Nachtigall et al., 2018) are considered. We do not believe that Level A 
harassment is a likely outcome for any mid-frequency cetacean and do 
not propose to authorize any take by Level A harassment for these 
species.
    The Level A and Level B harassment estimates are based on a 
consideration of the number of marine mammals that could be within the 
area around the operating airgun array where received levels of sound 
>=160 dB re 1 [micro]Pa rms are predicted to occur (see table 1). The 
estimated numbers are based on the densities (numbers per unit area) of 
marine mammals expected to occur in the area in the absence of seismic 
surveys. To the extent that marine mammals tend to move away from 
seismic sources before the sound level reaches the criterion level and 
tend not to approach an operating airgun array, these estimates likely 
overestimate the numbers actually exposed to the specified level of 
sound.

Marine Mammal Occurrence

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information which 
will inform the take calculations.
    Habitat-based stratified marine mammal densities for the North 
Atlantic and Puerto Rico are taken from the US Navy Atlantic Fleet 
Training and Testing Area Marine Mammal Density (Roberts et al., 2023; 
Mannocci et al., 2017), which represent the best available information 
regarding marine mammal densities in the survey area. This density 
information incorporates visual line-transect surveys of marine mammals 
for over 35 years, resulting in various studies that estimated the 
abundance, density, and distributions of marine mammal populations. The 
habitat-based density models consisted of 10 km x 10 km grid cells. 
Densities in the grid cells for the AFTT Area south of 21[deg] N were 
averaged per month for each of two water depth categories (intermediate 
and deep); for most months, the densities for each species were the 
same. More information is available online at https://seamap.env.duke.edu/models/Duke/AFTT/.
    For most species, the average monthly densities were the same 
throughout the year; densities for fin whale, sei whale, humpback 
whale, and Atlantic white-sided dolphin varied by month, so the highest 
monthly densities were used.

Take Estimation

    Here we describe how the information provided above is synthesized 
to produce a quantitative estimate of the take that is reasonably 
likely to occur and authorized. In order to estimate the number of 
marine mammals predicted to be exposed to sound levels that would 
result in Level A or Level B harassment, radial distances from the 
airgun array to the predicted isopleth corresponding to the Level A 
harassment and Level B harassment thresholds are calculated, as 
described above. Those radial distances are then used to calculate the 
area(s) around the airgun array predicted to be ensonified to sound 
levels that exceed the harassment thresholds. The distance for the 160-
dB Level B harassment threshold and PTS (Level A harassment) thresholds 
(based on L-DEO model results) was used to draw a buffer around the 
area expected to be ensonified (i.e., the survey area). The ensonified 
areas were then increased by 25 percent to account for potential 
delays, which is the equivalent to adding 25 percent to the line km to 
be surveyed. The density for each species was then multiplied by the 
daily ensonified areas (increased as described above), and then 
multiplied by the number of survey days (24) to estimate potential 
takes (see Appendix B of L-DEO's application for more information).
    L-DEO generally assumed that their estimates of marine mammal 
exposures above harassment thresholds equate to take and requested 
authorization of those takes. Those estimates in turn form the basis 
for our take authorization numbers. For the species for which NMFS does 
not expect there to be a reasonable potential for take by Level A 
harassment to occur, i.e., mid-frequency cetaceans, we have added L-
DEO's estimated exposures above Level A harassment thresholds to their 
estimated exposures above the Level B harassment threshold to produce a 
total number of incidents of take by Level B harassment that is 
authorized. Estimated exposures and take numbers for authorization are 
shown in table 6. As requested by L-DEO with NMFS concurrence, when 
zero take was calculated we have authorized one group size of take as a

[[Page 70946]]

precaution for species that could potentially occur in the survey area.

                                                                  Table 6--Take Numbers
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   Estimated take          Authorized take        Modeled
                   Species                                 Stock              ------------------------------------------------   abundance    Percent of
                                                                                 Level B     Level A     Level B     Level A        \2\         stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale..............................  Gulf of Maine..................         262          12         262          12         4,990          5.5
Fin whale...................................  Western North Atlantic.........         0.4           0       \1\ 2           0        11,672          0.2
Sei whale...................................  Nova Scotia....................          22           1          22           1        19,530          0.1
Minke whale.................................  Canadian East Coast............          58           3          58           3        13,784          0.4
Blue whale..................................  Western North Atlantic.........           1           0           1           0           191          0.5
Sperm whale.................................  North Atlantic.................         481           1         482           0        64,105          0.8
Kogia spp...................................  ...............................         354          14         354          14        26,043          1.4
Beaked whale................................  ...............................         539           1         540           0        65,069          0.8
Pilot whales................................  ...............................       1,830           3       1,833           0       264,907          0.7
Rough-toothed dolphin.......................  Western North Atlantic.........         476           1         477           0        32,848          1.5
Bottlenose dolphin..........................  Western North Atlantic Offshore       2,128           4       2,132           0       418,151          0.5
Pantropical spotted dolphin.................  Western North Atlantic.........         778           1         779           0       321,740          0.2
Atlantic spotted dolphin....................  Western North Atlantic.........       1,537           3       1,540           0       259,519          0.6
Spinner dolphin.............................  Western North Atlantic.........       1,928           4       1,932           0       152,511          1.3
Clymene dolphin.............................  Western North Atlantic.........       1,586           3       1,589           0       181,209          0.9
Striped dolphin.............................  Western North Atlantic.........         317           1         318           0       412,729          0.1
Fraser's dolphin............................  Western North Atlantic.........         213           0         213           0        19,585          1.1
Risso's dolphin.............................  Western North Atlantic.........         164           0         164           0        78,205          0.2
Common dolphin..............................  Western North Atlantic.........          88           0          88           0       473,260         <0.1
Melon-headed whale..........................  Western North Atlantic.........         985           2         987           0        64,114          1.5
Pygmy killer whale..........................  Western North Atlantic.........         130           0         130           0         9,001          1.4
False killer whale..........................  Western North Atlantic.........         218           0         218           0        12,682          1.7
Killer whale................................  Western North Atlantic.........           2           0           2           0           972          0.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Group size from Jefferson et al., 2015.
\2\ Modeled abundance (Roberts et al., 2023).

Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks, and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, and impact on 
operations.

Vessel-Based Visual Mitigation Monitoring

    Visual monitoring requires the use of trained observers (herein 
referred to as visual protected species observers (PSO)) to scan the 
ocean surface for the presence of marine mammals. The area to be 
scanned visually includes primarily the shutdown zone (SZ), within 
which observation of certain marine mammals requires shutdown of the 
acoustic source, but also a buffer zone and, to the extent possible 
depending on conditions, the surrounding waters. The buffer zone means 
an area beyond the SZ to be monitored for the presence of marine 
mammals that may enter the SZ. During pre-start clearance monitoring 
(i.e., before ramp-up begins), the buffer zone also acts as an 
extension of the SZ in that observations of marine mammals within the 
buffer zone would also prevent airgun operations from beginning (i.e., 
ramp-up). The buffer zone encompasses the area at and below the sea 
surface from the edge of the 0-500 m SZ, out to a radius of 1,000 m 
from the edges of the airgun array (500-1,000 m). This 1,000-m zone (SZ 
plus buffer) represents the pre-start clearance zone. Visual monitoring 
of the SZ and adjacent waters is intended to establish and, when visual 
conditions allow, maintain zones around the sound source that are clear 
of marine mammals, thereby reducing or eliminating the potential for 
injury and minimizing the potential for more severe behavioral 
reactions for animals occurring closer to the vessel. Visual monitoring 
of the buffer zone is intended to (1) provide additional protection to 
marine mammals that may be in the vicinity of the vessel during pre-
start clearance, and (2) during airgun use, aid in establishing and 
maintaining the SZ by alerting the visual observer and crew of marine 
mammals that are outside of, but may approach and enter, the SZ.
    L-DEO must use dedicated, trained, and NMFS-approved PSOs. The PSOs 
must have no tasks other than to conduct observational effort, record 
observational data, and communicate with and instruct relevant vessel 
crew with regard to the presence of marine mammals and mitigation 
requirements. PSO resumes shall be provided to NMFS for approval.
    At least one of the visual and two of the acoustic PSOs (discussed 
below) aboard the vessel must have a minimum of 90 days at-sea 
experience working in those roles, respectively, with no more

[[Page 70947]]

than 18 months elapsed since the conclusion of the at-sea experience. 
One visual PSO with such experience shall be designated as the lead for 
the entire protected species observation team. The lead PSO shall serve 
as primary point of contact for the vessel operator and ensure all PSO 
requirements per the IHA are met. To the maximum extent practicable, 
the experienced PSOs should be scheduled to be on duty with those PSOs 
with appropriate training but who have not yet gained relevant 
experience.
    During survey operations (e.g., any day on which use of the airgun 
array is planned to occur, and whenever the airgun array is in the 
water, whether activated or not), a minimum of two visual PSOs must be 
on duty and conducting visual observations at all times during daylight 
hours (i.e., from 30 minutes prior to sunrise through 30 minutes 
following sunset). Visual monitoring of the pre-start clearance zone 
must begin no less than 30 minutes prior to ramp-up, and monitoring 
must continue until 1 hour after use of the airgun array ceases or 
until 30 minutes past sunset. Visual PSOs shall coordinate to ensure 
360[deg] visual coverage around the vessel from the most appropriate 
observation posts, and shall conduct visual observations using 
binoculars and the naked eye while free from distractions and in a 
consistent, systematic, and diligent manner.
    PSOs shall establish and monitor the shutdown and buffer zones. 
These zones shall be based upon the radial distance from the edges of 
the airgun array (rather than being based on the center of the array or 
around the vessel itself). During use of the airgun array (i.e., 
anytime airguns are active, including ramp-up), detections of marine 
mammals within the buffer zone (but outside the SZ) shall be 
communicated to the operator to prepare for the potential shutdown of 
the airgun array. Visual PSOs will immediately communicate all 
observations to the on duty acoustic PSO(s), including any 
determination by the PSO regarding species identification, distance, 
and bearing and the degree of confidence in the determination. Any 
observations of marine mammals by crew members shall be relayed to the 
PSO team. During good conditions (e.g., daylight hours; Beaufort sea 
state (BSS) 3 or less), visual PSOs shall conduct observations when the 
airgun array is not operating for comparison of sighting rates and 
behavior with and without use of the airgun array and between 
acquisition periods, to the maximum extent practicable.
    Visual PSOs may be on watch for a maximum of 4 consecutive hours 
followed by a break of at least 1 hour between watches and may conduct 
a maximum of 12 hours of observation per 24-hour period. Combined 
observational duties (visual and acoustic but not at same time) may not 
exceed 12 hours per 24-hour period for any individual PSO.
    L-DEO must notify the NMFS Southeast Regional Office (SERO), Nicole 
Angeli (DPNR Virgin Islands), and Grisel Rodriguez Ferrer (DNR Puerto 
Rico) of the start and end date of airgun operations in the survey area 
via email ([email protected]; 
[email protected]; [email protected]).

Passive Acoustic Monitoring

    Passive acoustic monitoring (PAM) means the use of trained 
personnel (sometimes referred to as PAM operators, herein referred to 
as acoustic PSOs) to operate PAM equipment to acoustically detect the 
presence of marine mammals. Acoustic monitoring involves acoustically 
detecting marine mammals regardless of distance from the source, as 
localization of animals may not always be possible. Acoustic monitoring 
is intended to further support visual monitoring (during daylight 
hours) in maintaining an SZ around the sound source that is clear of 
marine mammals. In cases where visual monitoring is not effective 
(e.g., due to weather, nighttime), acoustic monitoring may be used to 
allow certain activities to occur, as further detailed below.
    PAM would take place in addition to the visual monitoring program. 
Visual monitoring typically is not effective during periods of poor 
visibility or at night, and even with good visibility, is unable to 
detect marine mammals when they are below the surface or beyond visual 
range. Acoustic monitoring can be used in addition to visual 
observations to improve detection, identification, and localization of 
cetaceans. The acoustic monitoring would serve to alert visual PSOs (if 
on duty) when vocalizing cetaceans are detected. It is only useful when 
marine mammals vocalize, but it can be effective either by day or by 
night, and does not depend on good visibility. It would be monitored in 
real time so that the visual observers can be advised when cetaceans 
are detected.
    The R/V Langseth will use a towed PAM system, which must be 
monitored by at a minimum one on duty acoustic PSO beginning at least 
30 minutes prior to ramp-up and at all times during use of the airgun 
array. Acoustic PSOs may be on watch for a maximum of 4 consecutive 
hours followed by a break of at least 1 hour between watches and may 
conduct a maximum of 12 hours of observation per 24-hour period. 
Combined observational duties (acoustic and visual but not at same 
time) may not exceed 12 hours per 24-hour period for any individual 
PSO.
    Survey activity may continue for 30 minutes when the PAM system 
malfunctions or is damaged, while the PAM operator diagnoses the issue. 
If the diagnosis indicates that the PAM system must be repaired to 
solve the problem, operations may continue for an additional 10 hours 
without acoustic monitoring during daylight hours only under the 
following conditions:
     Sea state is less than or equal to BSS 4;
     No marine mammals (excluding delphinids) detected solely 
by PAM in the applicable SZ in the previous 2 hours;
     NMFS is notified via email as soon as practicable with the 
time and location in which operations began occurring without an active 
PAM system; and
     Operations with an active airgun array, but without an 
operating PAM system, do not exceed a cumulative total of 10 hours in 
any 24-hour period.

Establishment of Shutdown and Pre-Start Clearance Zones

    A SZ is a defined area within which occurrence of a marine mammal 
triggers mitigation action intended to reduce the potential for certain 
outcomes, e.g., auditory injury, disruption of critical behaviors. The 
PSOs must establish and monitor shutdown zones and additional buffer 
zones. During high energy survey effort,\1\ the shutdown zone shall be 
500 m with an additional 500 m buffer zone (total 1,000 m). During low 
energy survey effort,\2\ the shutdown zone shall be 100 m with an 
additional 100 m buffer zone (total 200 m).
---------------------------------------------------------------------------

    \1\ High-energy survey effort refers to use of the 36-airgun, 
6,600 in\3\ array.
    \2\ Low-energy survey effort refers to use of the 2 45/105-in\3\ 
GI airguns, 90-in\3\ array.
---------------------------------------------------------------------------

    The 500 m or 100 m SZ would be based on radial distance from the 
edge of the airgun array (rather than being based on the center of the 
array or around the vessel itself). With certain exceptions (described 
below), if a marine mammal appears within or enters this zone, the 
airgun array would be shut down.
    The pre-start clearance zone is defined as the area that must be 
clear of marine mammals prior to beginning ramp-up of the airgun array, 
and includes the SZ plus the buffer zone.

[[Page 70948]]

Detections of marine mammals within the pre-start clearance zone would 
prevent airgun operations from beginning (i.e., ramp-up).
    The 500 m or 100 m SZ is intended to be precautionary in the sense 
that it would be expected to contain sound exceeding the injury 
criteria for all cetacean hearing groups, (based on the dual criteria 
of SELcum and peak Sound Pressure Level (SPL)), while also 
providing a consistent, reasonably observable zone within which PSOs 
would typically be able to conduct effective observational effort. 
Additionally, a 500 m or 100 m SZ is expected to minimize the 
likelihood that marine mammals will be exposed to levels likely to 
result in more severe behavioral responses. Although significantly 
greater distances may be observed from an elevated platform under good 
conditions, we believe that 500 m or 100 m is likely regularly 
attainable for PSOs using the naked eye during typical conditions. The 
pre-start clearance zone simply represents the addition of a buffer to 
the SZ, doubling the SZ size during pre-clearance.
    An extended SZ of 1,500 m or 500 m must be enforced for all beaked 
whales and Kogia species. No buffer of this extended SZ is required, as 
NMFS concludes that this extended SZ is sufficiently protective to 
mitigate harassment to beaked whales and Kogia species.

Pre-Start Clearance and Ramp-Up

    Ramp-up (sometimes referred to as ``soft start'') means the gradual 
and systematic increase of emitted sound levels from an airgun array. 
Ramp-up begins by first activating a single airgun of the smallest 
volume, followed by doubling the number of active elements in stages 
until the full complement of an array's airguns are active. Each stage 
should be approximately the same duration, and the total duration 
should not be less than approximately 20 minutes. The intent of pre-
start clearance observation (30 minutes) is to ensure no marine mammals 
are observed within the pre-start clearance zone (or extended SZ, for 
beaked whales and Kogia spp.) prior to the beginning of ramp-up. During 
the pre-start clearance period is the only time observations of marine 
mammals in the buffer zone would prevent operations (i.e., the 
beginning of ramp-up). The intent of ramp-up is to warn marine mammals 
of pending seismic survey operations and to allow sufficient time for 
those animals to leave the immediate vicinity prior to the sound source 
reaching full intensity. A ramp-up procedure, involving a step-wise 
increase in the number of airguns firing and total array volume until 
all operational airguns are activated and the full volume is achieved, 
is required at all times as part of the activation of the airgun array. 
All operators must adhere to the following pre-start clearance and 
ramp-up requirements:
     The operator must notify a designated PSO of the planned 
start of ramp-up as agreed upon with the lead PSO; the notification 
time should not be less than 60 minutes prior to the planned ramp-up in 
order to allow the PSOs time to monitor the pre-start clearance zone 
(and extended SZ) for 30 minutes prior to the initiation of ramp-up 
(pre-start clearance);
     Ramp-ups shall be scheduled so as to minimize the time 
spent with the source activated prior to reaching the designated run-
in;
     One of the PSOs conducting pre-start clearance 
observations must be notified again immediately prior to initiating 
ramp-up procedures and the operator must receive confirmation from the 
PSO to proceed;
     Ramp-up may not be initiated if any marine mammal is 
within the applicable shutdown or buffer zone. If a marine mammal is 
observed within the pre-start clearance zone (or extended SZ, for 
beaked whales and Kogia species) during the 30 minute pre-start 
clearance period, ramp-up may not begin until the animal(s) has been 
observed exiting the zones or until an additional time period has 
elapsed with no further sightings (15 minutes for small odontocetes, 
and 30 minutes for all mysticetes and all other odontocetes, including 
sperm whales, beaked whales, and large delphinids, such as pilot 
whales);
     Ramp-up shall begin by activating a single airgun of the 
smallest volume in the array and shall continue in stages by doubling 
the number of active elements at the commencement of each stage, with 
each stage of approximately the same duration. Duration shall not be 
less than 20 minutes. The operator must provide information to the PSO 
documenting that appropriate procedures were followed;
     PSOs must monitor the pre-start clearance zone (and 
extended SZ) during ramp-up, and ramp-up must cease and the source must 
be shut down upon detection of a marine mammal within the applicable 
zone. Once ramp-up has begun, detections of marine mammals within the 
buffer zone do not require shutdown, but such observation shall be 
communicated to the operator to prepare for the potential shutdown;
     Ramp-up may occur at times of poor visibility, including 
nighttime, if appropriate acoustic monitoring has occurred with no 
detections in the 30 minutes prior to beginning ramp-up. Airgun array 
activation may only occur at times of poor visibility where operational 
planning cannot reasonably avoid such circumstances;
     If the airgun array is shut down for brief periods (i.e., 
less than 30 minutes) for reasons other than implementation of 
prescribed mitigation (e.g., mechanical difficulty), it may be 
activated again without ramp-up if PSOs have maintained constant visual 
and/or acoustic observation and no visual or acoustic detections of 
marine mammals have occurred within the pre-start clearance zone (or 
extended SZ, where applicable). For any longer shutdown, pre-start 
clearance observation and ramp-up are required; and
     Testing of the airgun array involving all elements 
requires ramp-up. Testing limited to individual source elements or 
strings does not require ramp-up but does require pre-start clearance 
of 30 minutes.

Shutdown

    The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array. Any PSO on 
duty will have the authority to delay the start of survey operations or 
to call for shutdown of the airgun array if a marine mammal is detected 
within the applicable SZ. The operator must also establish and maintain 
clear lines of communication directly between PSOs on duty and crew 
controlling the airgun array to ensure that shutdown commands are 
conveyed swiftly while allowing PSOs to maintain watch. When both 
visual and acoustic PSOs are on duty, all detections will be 
immediately communicated to the remainder of the on-duty PSO team for 
potential verification of visual observations by the acoustic PSO or of 
acoustic detections by visual PSOs. When the airgun array is active 
(i.e., anytime one or more airguns is active, including during ramp-up) 
and (1) a marine mammal appears within or enters the applicable SZ and/
or (2) a marine mammal (other than delphinids, see below) is detected 
acoustically and localized within the applicable SZ, the airgun array 
will be shut down. When shutdown is called for by a PSO, the airgun 
array will be immediately deactivated and any dispute resolved only 
following deactivation. Additionally, shutdown will occur whenever PAM 
alone (without visual sighting), confirms presence of marine mammal(s) 
in the SZ. If the acoustic PSO cannot confirm presence within the SZ, 
visual PSOs

[[Page 70949]]

will be notified but shutdown is not required.
    Following a shutdown, airgun activity would not resume until the 
marine mammal has cleared the SZ. The animal would be considered to 
have cleared the SZ if it is visually observed to have departed the SZ 
(i.e., animal is not required to fully exit the buffer zone where 
applicable), or it has not been seen within the SZ for 15 minutes for 
small odontocetes, or 30 minutes for all mysticetes and all other 
odontocetes, including sperm whales, beaked whales, Kogia species, and 
large delphinids, such as pilot whales.
    The shutdown requirement is waived for small dolphins if an 
individual is detected within the SZ. As defined here, the small 
dolphin group is intended to encompass those members of the Family 
Delphinidae most likely to voluntarily approach the source vessel for 
purposes of interacting with the vessel and/or airgun array (e.g., bow 
riding). This exception to the shutdown requirement applies solely to 
specific genera of small dolphins (Delphinus, Lagenodelphis, Stenella, 
Steno, and Tursiops).
    We include this small dolphin exception because shutdown 
requirements for small dolphins under all circumstances represent 
practicability concerns without likely commensurate benefits for the 
animals in question. Small dolphins are generally the most commonly 
observed marine mammals in the specific geographic region and would 
typically be the only marine mammals likely to intentionally approach 
the vessel. As described above, auditory injury is extremely unlikely 
to occur for 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 dolphins 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
(e.g., Barkaszi et al., 2012, Barkaszi and Kelly, 2018). The potential 
for increased shutdowns resulting from such a measure would require the 
Langseth 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 dolphins, they are much less likely to 
approach vessels. Therefore, retaining a shutdown requirement for large 
delphinids would not have similar impacts in terms of either 
practicability for the applicant or corollary increase in sound energy 
output and time on the water. We do anticipate some benefit for a 
shutdown requirement for large delphinids in that it simplifies 
somewhat the total range of decision-making for PSOs and may preclude 
any potential for physiological effects other than to the auditory 
system as well as some more severe behavioral reactions for any such 
animals in close proximity to the Langseth.
    Visual PSOs shall use best professional judgment in making the 
decision to call for a shutdown if there is uncertainty regarding 
identification (i.e., whether the observed marine mammal(s) belongs to 
one of the delphinid genera for which shutdown is waived or one of the 
species with a larger SZ).
    L-DEO must implement shutdown if a marine mammal species for which 
take was not authorized, or a species for which authorization was 
granted but the authorized takes have been met, approaches the Level A 
or Level B harassment zones. L-DEO must also implement an extended 
shutdown (1,500 m for the high energy or 500 m for the low energy) if 
any large whale (defined as a sperm whale or any mysticete species) 
with a calf (defined as an animal less than two-thirds the body size of 
an adult observed to be in close association with an adult) and/or an 
aggregation of six or more large whales are observed at any distance.

Vessel Strike Avoidance

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

Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing

[[Page 70950]]

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

Vessel-Based Visual Monitoring

    As described above, PSO observations would take place during 
daytime airgun operations. During seismic survey operations, at least 
five visual PSOs would be based aboard the Langseth. Two visual PSOs 
would be on duty at all times during daytime hours. Monitoring shall be 
conducted in accordance with the following requirements:
     The operator shall provide PSOs with bigeye binoculars 
(e.g., 25 x 150; 2.7 view angle; individual ocular focus; height 
control) of appropriate quality solely for PSO use. These shall be 
pedestal-mounted on the deck at the most appropriate vantage point that 
provides for optimal sea surface observation, PSO safety, and safe 
operation of the vessel; and
     The operator will work with the selected third-party 
observer provider to ensure PSOs have all equipment (including backup 
equipment) needed to adequately perform necessary tasks, including 
accurate determination of distance and bearing to observed marine 
mammals.
    PSOs must have the following requirements and qualifications:
     PSOs shall be independent, dedicated, trained visual and 
acoustic PSOs and must be employed by a third-party observer provider;
     PSOs shall have no tasks other than to conduct 
observational effort (visual or acoustic), collect data, and 
communicate with and instruct relevant vessel crew with regard to the 
presence of protected species and mitigation requirements (including 
brief alerts regarding maritime hazards);
     PSOs shall have successfully completed an approved PSO 
training course appropriate for their designated task (visual or 
acoustic). Acoustic PSOs are required to complete specialized training 
for operating PAM systems and are encouraged to have familiarity with 
the vessel with which they will be working;
     PSOs can act as acoustic or visual observers (but not at 
the same time) as long as they demonstrate that their training and 
experience are sufficient to perform the task at hand;
     NMFS must review and approve PSO resumes accompanied by a 
relevant training course information packet that includes the name and 
qualifications (i.e., experience, training completed, or educational 
background) of the instructor(s), the course outline or syllabus, and 
course reference material as well as a document stating successful 
completion of the course;
     PSOs must successfully complete relevant training, 
including completion of all required coursework and passing (80 percent 
or greater) a written and/or oral examination developed for the 
training program;
     PSOs must have successfully attained a bachelor's degree 
from an accredited college or university with a major in one of the 
natural sciences, a minimum of 30 semester hours or equivalent in the 
biological sciences, and at least one undergraduate course in math or 
statistics;
     The educational requirements may be waived if the PSO has 
acquired the relevant skills through alternate experience. Requests for 
such a waiver shall be submitted to NMFS and must include written 
justification. Requests shall be granted or denied (with justification) 
by NMFS within 1 week of receipt of submitted information. Alternate 
experience that may be considered includes, but is not limited to (1) 
secondary education and/or experience comparable to PSO duties; (2) 
previous work experience conducting academic, commercial, or 
government-sponsored protected species surveys; or (3) previous work 
experience as a PSO; the PSO should demonstrate good standing and 
consistently good performance of PSO duties;
     For data collection purposes, PSOs shall use standardized 
electronic data collection forms. PSOs shall record detailed 
information about any implementation of mitigation requirements, 
including the distance of animals to the airgun array and description 
of specific actions that ensued, the behavior of the animal(s), any 
observed changes in behavior before and after implementation of 
mitigation, and if shutdown was implemented, the length of time before 
any subsequent ramp-up of the airgun array. If required mitigation was 
not implemented, PSOs should record a description of the circumstances. 
At a minimum, the following information must be recorded:
    [cir] Vessel name, vessel size and type, maximum speed capability 
of vessel;
    [cir] Dates (MM/DD/YYYY) of departures and returns to port with 
port name;
    [cir] PSO names and affiliations, PSO ID (initials or other 
identifier);
    [cir] Date (MM/DD/YYYY) and participants of PSO briefings (as 
discussed in 3(d));
    [cir] Visual monitoring equipment used (description);
    [cir] PSO location on vessel and height (meters) of observation 
location above water surface;
    [cir] Watch status (description);
    [cir] Dates (MM/DD/YYYY) and times (Greenwich Mean Time/UTC) of 
survey on/off effort and times (GMC/UTC) corresponding with PSO on/off 
effort;
    [cir] Vessel location (decimal degrees) when survey effort began 
and ended and vessel location at beginning and end of visual PSO duty 
shifts;
    [cir] Vessel location (decimal degrees) at 30-second intervals if 
obtainable from data collection software, otherwise at practical 
regular interval;
    [cir] Vessel heading (compass heading) and speed (knots) at 
beginning and end of visual PSO duty shifts and upon any change;
    [cir] Water depth (meters) (if obtainable from data collection 
software);
    [cir] Environmental conditions while on visual survey (at beginning 
and end of

[[Page 70951]]

PSO shift and whenever conditions changed significantly), including BSS 
and any other relevant weather conditions including cloud cover, fog, 
sun glare, and overall visibility to the horizon;
    [cir] Factors that may have contributed to impaired observations 
during each PSO shift change or as needed as environmental conditions 
changed (description) (e.g., vessel traffic, equipment malfunctions); 
and
    [cir] Vessel/Survey activity information (and changes thereof) 
(description), such as airgun power output while in operation, number 
and volume of airguns operating in the array, tow depth of the array, 
and any other notes of significance (i.e., pre-start clearance, ramp-
up, shutdown, testing, shooting, ramp-up completion, end of operations, 
streamers, etc.); and
     Upon visual observation of any marine mammals, the 
following information must be recorded:
    [cir] Sighting ID (numeric);
    [cir] Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
    [cir] Location of PSO/observer (description);
    [cir] Vessel activity at the time of the sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other);
    [cir] PSO who sighted the animal/ID;
    [cir] Time/date of sighting (GMT/UTC, MM/DD/YYYY);
    [cir] Initial detection method (description);
    [cir] Sighting cue (description);
    [cir] Vessel location at time of sighting (decimal degrees);
    [cir] Water depth (meters);
    [cir] Direction of vessel's travel (compass direction);
    [cir] Speed (knots) of the vessel from which the observation was 
made;
    [cir] Direction of animal's travel relative to the vessel 
(description, compass heading);
    [cir] Bearing to sighting (degrees);
    [cir] Identification of the animal (e.g., genus/species, lowest 
possible taxonomic level, or unidentified) and the composition of the 
group if there is a mix of species;
    [cir] Species reliability (an indicator of confidence in 
identification) (1 = unsure/possible, 2 = probable, 3 = definite/sure, 
9 = unknown/not recorded);
    [cir] Estimated distance to the animal (meters) and method of 
estimating distance;
    [cir] Estimated number of animals (high/low/best) (numeric);
    [cir] Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
    [cir] Description (as many distinguishing features as possible of 
each individual seen, including length, shape, color, pattern, scars or 
markings, shape and size of dorsal fin, shape of head, and blow 
characteristics);
    [cir] Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding, 
traveling; as explicit and detailed as possible; note any observed 
changes in behavior);
    [cir] Animal's closest point of approach (meters) and/or closest 
distance from any element of the airgun array; and
    [cir] Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up) and time and location of the 
action.
    [cir] Photos (Yes/No);
    [cir] Photo Frame Numbers (List of numbers);
    [cir] Conditions at time of sighting (Visibility; Beaufort Sea 
State).
    If a marine mammal is detected while using the PAM system, the 
following information should be recorded:
     An acoustic encounter identification number, and whether 
the detection was linked with a visual sighting;
     Date and time when first and last heard;
     Types and nature of sounds heard (e.g., clicks, whistles, 
creaks, burst pulses, continuous, sporadic, strength of signal); and
     Any additional information recorded such as water depth of 
the hydrophone array, bearing of the animal to the vessel (if 
determinable), species or taxonomic group (if determinable), 
spectrogram screenshot, and any other notable information.

Reporting

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

Reporting Injured or Dead Marine Mammals

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

[[Page 70952]]

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

Actions To Minimize Additional Harm to Live-Stranded (or Milling) 
Marine Mammals

    In the event of a live stranding (or near-shore atypical milling) 
event in the U.S. Caribbean territories and/or within 50 km of the 
survey operations, where the NMFS stranding network is engaged in 
herding or other interventions to return animals to the water, the 
Director of OPR, NMFS (or designee), will advise L-DEO of the need to 
implement shutdown procedures for all active airgun arrays operating 
within 50 km of the stranding. Shutdown procedures for live stranding 
or milling marine mammals include the following: if at any time, the 
marine mammal(s) die or are euthanized, or if herding/intervention 
efforts are stopped, the Director of OPR, NMFS (or designee), will 
advise the IHA-holder that the shutdown around the animals' location is 
no longer needed. Otherwise, shutdown procedures will remain in effect 
until the Director of OPR, NMFS (or designee), determines and advises 
L-DEO that all live animals involved have left the area (either of 
their own volition or following an intervention).
    If further observations of the marine mammals indicate the 
potential for re-stranding, additional coordination with the IHA-holder 
will be required to determine what measures are necessary to minimize 
that likelihood (e.g., extending the shutdown or moving operations 
farther away) and to implement those measures as appropriate.
    Additional Information Requests--if NMFS determines that the 
circumstances of any marine mammal stranding found in the vicinity of 
the activity suggest investigation of the association with survey 
activities is warranted, and an investigation into the stranding is 
being pursued, NMFS will submit a written request to L-DEO indicating 
that the following initial available information must be provided as 
soon as possible, but no later than 7 business days after the request 
for information:
     Status of all sound source use in the 48 hours preceding 
the estimated time of stranding and within 50 km of the discovery/
notification of the stranding by NMFS; and
     If available, description of the behavior of any marine 
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and 
immediately after the discovery of the stranding.
    In the event that the investigation is still inconclusive, the 
investigation of the association of the survey activities is still 
warranted, and the investigation is still being pursued, NMFS may 
provide additional information requests, in writing, regarding the 
nature and location of survey operations prior to the time period 
above.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338; 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality, or ambient noise levels).
    To avoid repetition, the discussion of our analysis applies to all 
the species listed in table 1, given that the anticipated effects of 
this activity on these different marine mammal stocks are expected to 
be similar. Where there are meaningful differences between species or 
stocks they are included as separate subsections below. NMFS does not 
anticipate that serious injury or mortality would occur as a result of 
L-DEO's planned survey, even in the absence of mitigation, and no 
serious injury or mortality is authorized. As discussed in the 
Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat section above, non-auditory physical effects and vessel strike 
are not expected to occur. NMFS expects that the majority of potential 
takes would be in the form of short-term Level B behavioral harassment, 
resulting from temporary avoidance of the area or decreased foraging 
(if such activity was occurring), reactions that are considered to be 
of low severity and with no lasting biological consequences (e.g., 
Southall et al., 2007).
    We authorize a limited number of Level A harassment events of five 
species in the form of PTS (humpback whale, minke whale, sei whale, and 
Kogia spp), and Level B harassment only of the remaining marine mammal 
species. If any PTS is incurred in marine mammals as a result of the 
planned activity, we expect only a small degree of PTS that would not 
result in severe hearing impairment because of the constant movement of 
both the Langseth and of the marine mammals in the project areas, as 
well as the fact that the vessel is not expected to remain in any one 
area in which individual marine mammals would be expected to 
concentrate for an extended period of time. Additionally, L-DEO would 
shut down the airgun array if marine mammals approach within 500 m 
(with the exception of specific genera of dolphins, see Mitigation), 
further reducing the expected duration and intensity of sound, and 
therefore the likelihood of marine mammals incurring PTS. Since the 
duration of exposure to loud sounds will be relatively short it

[[Page 70953]]

would be unlikely to affect the fitness of any individuals. Also, as 
described above, we expect that marine mammals would likely move away 
from a sound source that represents an aversive stimulus, especially at 
levels that would be expected to result in PTS, given sufficient notice 
of the Langseth's approach due to the vessel's relatively low speed 
when conducting seismic surveys.
    In addition, the maximum expected Level B harassment zone around 
the survey vessel is 6,733 m for water depths greater than 1,000 m (and 
up to 10,100 m in water depths of 100 to 1,000 m). Therefore, the 
ensonified area surrounding the vessel is relatively small compared to 
the overall distribution of animals in the area and their use of the 
habitat. Feeding behavior is not likely to be significantly impacted as 
prey species are mobile and are broadly distributed throughout the 
survey area; therefore, marine mammals that may be temporarily 
displaced during survey activities are expected to be able to resume 
foraging once they have moved away from areas with disturbing levels of 
underwater noise. Because of the short duration (24 days) and temporary 
nature of the disturbance and the availability of similar habitat and 
resources in the surrounding area, the impacts to marine mammals and 
the food sources that they utilize are not expected to cause 
significant or long-term consequences for individual marine mammals or 
their populations.
    There are no rookeries, mating, or calving grounds known to be 
biologically important to marine mammals within the survey area and 
there are no feeding areas known to be biologically important to marine 
mammals within the survey area. There is no designated critical habitat 
for any ESA-listed marine mammals in the survey area.

Marine Mammal Species With Active Unusual Mortality Events (UMEs)

    As discussed above, there are several active UMEs occurring in the 
vicinity of L-DEO's survey area. Elevated humpback whale mortalities 
have occurred along the Atlantic coast from Maine through Florida since 
January 2016. Of the cases examined, approximately half had evidence of 
human interaction (ship strike or entanglement). The UME does not yet 
provide cause for concern regarding population-level impacts. Despite 
the UME, the relevant population of humpback whales (the West Indies 
breeding population, or DPS) remains stable at approximately 12,000 
individuals.
    Beginning in January 2017, elevated minke whale strandings have 
occurred along the Atlantic coast from Maine through South Carolina, 
with highest numbers in Massachusetts, Maine, and New York. This event 
does not provide cause for concern regarding population level impacts, 
as the likely population abundance is greater than 20,000 whales, and 
the UME is pending closure. Although, the populations experiencing the 
UME's may not be the same as the populations impacted by the survey.
    Additionally, the mitigation measures are expected to reduce the 
number and/or severity of takes for all species listed in table 1, 
including those with active UMEs, to the level of least practicable 
adverse impact. In particular they would provide animals the 
opportunity to move away from the sound source throughout the survey 
area before seismic survey equipment reaches full energy, thus 
preventing them from being exposed to sound levels that have the 
potential to cause injury (Level A harassment) or more severe Level B 
harassment.
    In summary and as described above, the following factors primarily 
support our determination that the impacts resulting from this activity 
are not expected to adversely affect any of the species or stocks 
through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or 
authorized;
     The activity is temporary and of relatively short duration 
(40 days);
     The vast majority of anticipated impacts of the activity 
on marine mammals would be temporary behavioral changes due to 
avoidance of the area around the vessel;
     The availability of alternative areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the survey to avoid exposure to sounds from the activity is readily 
abundant;
     The potential adverse effects on fish or invertebrate 
species that serve as prey species for marine mammals from the survey 
would be temporary and spatially limited, and impacts to marine mammal 
foraging would be minimal;
     The mitigation measures are expected to reduce the number 
of takes by Level A harassment (in the form of PTS) by allowing for 
detection of marine mammals in the vicinity of the vessel by visual and 
acoustic observers; and
     The mitigation measures, including visual and acoustic 
shutdowns 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 monitoring and mitigation 
measures, NMFS finds that the total marine mammal take from the 
activity will have a negligible impact on all affected marine mammal 
species or stocks.

Small Numbers

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

Unmitigable Adverse Impact Analysis and Determination

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

[[Page 70954]]

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 within NMFS' OPR.
    The NMFS OPR ESA Interagency Cooperation Division issued a 
Biological Opinion under section 7 of the ESA, on the issuance of an 
IHA to L-DEO under section 101(a)(5)(D) of the MMPA by the NMFS OPR 
Permits and Conservation Division. The Biological Opinion concluded 
that the action is not likely to jeopardize the continued existence of 
ESA-listed blue whales, fin whales, sei whales, and sperm whales.

National Environmental Policy Act (NEPA)

    In compliance with the National Environmental Policy Act of 1969 
(42 U.S.C. 4321 et seq.), as implemented by the regulations published 
by the Council on Environmental Quality (40 CFR parts 1500-1508), the 
NSF prepared an Environmental Analysis (EA) to consider the direct, 
indirect, and cumulative effects to the human environment from the 
planned marine geophysical survey off of Puerto Rico. NSF's EA was made 
available to the public for review and comment in relation to its 
suitability for adoption by NMFS in order to assess the impacts to the 
human environment of issuance of an IHA to L-DEO. In compliance with 
NEPA and the Council on Environmental Quality regulations, as well as 
NOAA Administrative Order 216-6, NMFS has reviewed the NSF's EA, 
determined it to be sufficient, and adopted that EA and signed a 
Finding of No Significant Impact (FONSI) available on our website at 
https://www.fisheries.noaa.gov/action/incidental-take-authorization-lamont-doherty-earth-observatorys-marine-geophysical-surveys. NSF's EA 
is available at https://www.nsf.gov/geo/oce/envcomp/.

Authorization

    NMFS has issued an IHA to L-DEO for the incidental harassment of 
small numbers of 27 marine mammal species incidental to a marine 
geophysical survey of Puerto Rico in the Northwest Atlantic Ocean that 
includes previously explained mitigation, monitoring and reporting 
requirements.

    Dated: October 10, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-22632 Filed 10-12-23; 8:45 am]
BILLING CODE 3510-22-P`