Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey Off North Carolina in the Northwest Atlantic Ocean, 30282-30299 [2023-10024]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 88, Number 91 (Thursday, May 11, 2023)]
[Notices]
[Pages 30282-30299]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-10024]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XC977]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Marine Geophysical Survey Off 
North Carolina 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.

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

DATES: This Authorization is effective from May 5, 2023 through May 4, 
2024.

FOR FURTHER INFORMATION CONTACT: Rachel Wachtendonk, Office of 
Protected Resources, NMFS, (301) 427-8401. Electronic copies of the 
application and supporting documents, as well as a list of the 
references cited in this document, may be obtained online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. In case of problems 
accessing these documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION: 

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are proposed or, if the taking is limited to harassment, a notice of a 
proposed 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 October 12, 2022, NMFS received a request from L-DEO for an IHA 
to take marine mammals incidental to a marine geophysical survey off 
the coast of North Carolina in the northwest Atlantic Ocean. The 
application was deemed adequate and complete on January 13, 2023. L-DEO 
requested authorization for the take of 30 species of marine mammals by 
Level B harassment and, for 2 of these species, by Level A harassment. 
The proposed IHA was published on March 23, 2023 (88 FR 17646). Neither 
L-DEO, nor NMFS expect serious injury or mortality to result from this 
activity and, therefore, an IHA is appropriate.

[[Page 30283]]

Description of Activity

Overview

    Researchers from the University of Texas at Austin (UT) and L-DEO, 
with funding from the NSF, and in collaboration with international and 
domestic researchers including the United States Geological Survey 
(USGS), propose to conduct research, including high-energy seismic 
surveys using airguns as the acoustic source, from the research vessel 
(R/V) Marcus G. Langseth (Langseth). The survey will occur off North 
Carolina in the northwestern Atlantic Ocean during spring/summer 2023. 
The multi-channel seismic (MCS) reflection survey will occur within the 
Exclusive Economic Zone (EEZ) of the United States and in international 
waters, in depths ranging from 200 to 5,500 meters (m). To complete 
this survey, the R/V Langseth will tow an 18-airgun array consisting of 
Bolt airguns ranging from 40-360 cubic inch (in\3\) each on two strings 
spaced 6 m apart, with a total discharge volume of 3,300 in\3\. The 
acoustic source will be towed at 6 m deep along the survey lines, while 
the receiving system will consist of a 5 kilometer (km) solid-state 
hydrophone streamer towed at a depth of 6 m and a 600 m long solid-
state hydrophone streamer towed at a depth of 2 to 3 m.

Dates and Duration

    The survey is expected to last for 33 days, with approximately 28 
days of seismic operations, 3 days of piston coring and heat flow 
measurements, and 2 days of transit. R/V Langseth will likely leave 
from and return to port in Norfolk, VA, during spring/summer 2023.

Specific Geographic Region

    The survey will occur within ~31-35[deg] N lat., ~72-75[deg] W 
long. off the coast of North Carolina in the Northwest Atlantic Ocean. 
The closest point of approach of the survey area to the coast will be 
approximately 40 km (from Cape Hatteras, North Carolina). 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. The surveys are planned to occur within the EEZ of the U.S. 
and in international waters, in depths ranging from 200-5,500 m deep.

[[Page 30284]]

[GRAPHIC] [TIFF OMITTED] TN11MY23.008

    A detailed description of the planned geophysical survey is 
provided in the Federal Register notice for the proposed IHA (88 FR 
17646, March 23, 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 specific activity.

Comments and Responses

    A notice of proposed IHA was published to the Federal Register on 
March 23, 2023 (88 FR 17646). That notice described, in detail, L-DEO's 
activity, the marine mammal species that may be affected by the 
activity, and the anticipated effects on marine mammals. During the 30-
day public comment period, NMFS did not receive any public comments.

Changes From the Proposed IHA to Final IHA

    Changes were made between publication of the notice of proposed IHA 
and this notice of final IHA. Additional reporting has been required to 
notify NOAA's Southeast Regional Office (SERO) on the start and end 
date of seismic operations, as well as providing daily observations if 
any non-seismic activities are conducted between November and April 
(note that use of airguns is prohibited during this period). Specific 
language regarding the 10-knot (kn) speed restrictions in Seasonal and 
Dynamic Management Areas (SMA and DMA) for North Atlantic right whale 
protection was added under the vessel strike avoidance regulations. 
Lastly, the contact information for the NMFS North Atlantic Right Whale 
Sighting Advisory System was corrected.

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of L-DEO's application summarize available 
information regarding status and trends, distribution and habitat 
preferences, and behavior and life history, of the potentially affected 
species. Additional information regarding population trends and threats 
may be found in NMFS' 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 (www.fisheries.noaa.gov/find-species). NMFS refers the reader 
to the application and to the aforementioned

[[Page 30285]]

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 
optimum sustainable population (as described in NMFS' SARs). While no 
serious injury or mortality is expected to occur, 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 stocks managed under the MMPA in this region 
are assessed in NMFS' U.S. Atlantic and Gulf of Mexico SARs (e.g., 
Hayes et al., 2019, 2020, 2022). All values presented in Table 1 are 
the most recent available (including the draft 2022 SARs) at the time 
of publication and are available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                              Table 1--Species Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                        ESA/MMPA status;   Stock abundance (CV,
             Common name                  Scientific name               Stock           strategic (Y/N)      Nmin, most recent       PBR     Annual M/SI
                                                                                              \1\          abundance survey) \2\                 \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
    Humpback whale..................  Megaptera novaeangliae.  Gulf of Maine.........  -/-; N             1,396 (0; 1,380; 2016)         22        12.15
    Fin whale.......................  Balaenoptera physalus..  Western North Atlantic  E/D; Y             6,802 (0.24; 5,573;            11          1.8
                                                                                                           2016).
    Sei whale.......................  Balaenoptera borealis..  Nova Scotia...........  E/D; Y             6,292 (1.02; 3,098;           6.2          0.8
                                                                                                           2016).
    Minke whale.....................  Balaenoptera             Canadian East Coast...  -/-; N             21,968 (0.31; 17,002;         170         10.6
                                       acutorostrata.                                                      2016).
    Blue whale......................  Balaenoptera musculus..  Western North Atlantic  E/D;Y              unk (unk; 402; 1980-          0.8            0
                                                                                                           2008).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale.....................  Physeter macrocephalus.  North Atlantic........  E/D;Y              4,349 (0.28; 3,451;           3.9            0
                                                                                                           2016).
Family Kogiidae:
    Pygmy sperm whale...............  Kogia breviceps........  Western North Atlantic  -/-; N             7,750 (0.38; 5,689;            46            0
                                                                                                           2016).
    Dwarf sperm whale...............  Kogia sima.............  Western North Atlantic  -/-; N             7,750 (0.38; 5,689;            46            0
                                                                                                           2016).
Family Ziphiidae (beaked whales):
    Cuvier's beaked Whale...........  Ziphius cavirostris....  Western North Atlantic  -/-; N             5,744 (0.36; 4,282;            43          0.2
                                                                                                           2016).
    Blainville's beaked Whale.......  Mesoplodon densirostris  Western North Atlantic  -/-; N             10,107 (0.27; 8,085;           81            0
                                                                                                           2016).
    True's beaked whale.............  Mesoplodon mirus.......  Western North Atlantic  -/-; N             10,107 (0.27; 8,085;           81            0
                                                                                                           2016).
    Gervais' beaked whale...........  Mesoplodon europaeus...  Western North Atlantic  -/-; N             10,107 (0.27; 8,085;           81            0
                                                                                                           2016).
Family Delphinidae:
    Long-finned pilot whale.........  Globicephala melas.....  Western North Atlantic  -/-; N             39,215 (0.30; 30,627;         306            9
                                                                                                           2016).
    Short finned pilot whale........  Globicephala             Western North Atlantic  -/-;Y              28,924 (0.24; 23,637;         236          136
                                       macrorhynchus.                                                      2016).
    Rough-toothed dolphin...........  Steno bredanensis......  Western North Atlantic  -/-; N             136 (1.0; 67; 2016)...        0.7            0
    Bottlenose dolphin..............  Tursiops truncates.....  Western North Atlantic  -/-; N             62,851 (0.23; 51,914;         519           28
                                                                Offshore.                                  2016).
    Atlantic white-sided dolphin....  Lagenorhynchus acutus..  Western North Atlantic  -/-; N             93,233 (0.71; 54,443;         544           27
                                                                                                           2016).
    Pantropical spotted dolphin.....  Stenella attenuate.....  Western North Atlantic  -/-; N             6,593 (0.52; 4,367;            44            0
                                                                                                           2016).
    Atlantic spotted dolphin........  Stenella frontalis.....  Western North Atlantic  -/-; N             39,921 (0.27; 32,032;         320            0
                                                                                                           2016).
    Spinner dolphin.................  Stenella longirostris..  Western North Atlantic  -/-; N             4,102 (0.99; 2,045;            21            0
                                                                                                           2016).
    Clymene dolphin.................  Stenella clymene.......  Western North Atlantic  -/-; N             4,237 (1.03; 2,071;            21            0
                                                                                                           2016).
    Striped dolphin.................  Stenella coeruleoalba..  Western North Atlantic  -/-; N             67,036 (0.29; 52,939;         529            0
                                                                                                           2016).
    Fraser's dolphin................  Lagenodelphis hosei....  Western North Atlantic  -/-; N             unk...................        unk            0
    Risso's dolphin.................  Grampus griseus........  Western North Atlantic  -/-; N             35,215(0.19; 30,051;          301           34
                                                                                                           2016).
    Common dolphin..................  Delphinus delphis......  Western North Atlantic  -/-; N             172,947 (0.21;              1,452          390
                                                                                                           145,216; 2016).
    Melon-headed whale..............  Peponocephala electra..  Western North Atlantic  -/-; N             unk...................        unk            0
    Pygmy killer whale..............  Feresa attenuate.......  Western North Atlantic  -/-; N             unk...................        unk            0
    False killer whale..............  Pseudorca crassidens...  Western North Atlantic  -/-; N             1,791 (0.56; 1,154;            12            0
                                                                                                           2016).
    Killer whale....................  Orcinus orca...........  Western North Atlantic  -/-; N             unk...................        unk            0
Family Phocoenidae (porpoises):
    Harbor porpoise.................  Phocoena phocoena......  Gulf of Maine/Bay of    -/-; N             95,543 (0.31; 74,034;         851          164
                                                                Fundy.                                     2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum
  estimate of stock abundance.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.


[[Page 30286]]

    As indicated above, all 30 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 off North Carolina), 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 17646, March 23, 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           150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true    275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)     50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)    60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al., 2007) and PW pinniped (approximation).

    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information.

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 17646, March 23, 
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 
17646, March 23, 2023).

Estimated Take

    This section provides an estimate of the number of incidental takes 
authorized through the IHA, which will inform both NMFS' consideration 
of ``small numbers,'' and the negligible impact determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes will primarily be Level B harassment, as use of 
the described acoustic sources, particularly airgun arrays, is likely 
to disrupt behavioral patterns of marine mammals. There is also some 
potential for auditory injury (Level A harassment) to result for low- 
and high-frequency species due to the size of the predicted auditory 
injury zones for those species. 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 low- or 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 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

[[Page 30287]]

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 (e.g., 
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:   Cell 2: LE,LF,24h:
                                   219 dB;             199 dB.
                                   LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans....  Cell 3: Lpk,flat:   Cell 4: LE,MF,24h:
                                   230 dB;             198 dB.
                                   LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans...  Cell 5: Lpk,flat:   Cell 6: LE,HF,24h:
                                   202 dB;             173 dB.
                                   LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW)             Cell 7: Lpk,flat:   Cell 8: LE,PW,24h:
 (Underwater).                     218 dB;             201 dB.
                                   LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW)            Cell 9: Lpk,flat:   Cell 10:
 (Underwater).                     232 dB;             LE,OW,24h: 219
                                   LE,OW,24h: 203 dB.  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 [mu]Pa, and
  cumulative sound exposure level (LE) has a reference value of
  1[mu]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 NMFS Technical Guidance (2016) was published, in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a User Spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or occurrence to help predict takes. We note that 
because of some of the assumptions included in the methods used for 
these tools, we anticipate that isopleths produced are typically going 
to be overestimates of some degree, which may result in some degree of 
overestimate of Level A harassment take. However, these tools offer the 
best way to predict appropriate isopleths

[[Page 30288]]

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 will entail the use of a 18-airgun array with a total 
discharge of 3300 in\3\ at a tow depth of 6 m. L-DEO model results are 
used to determine the 160 dBrms radius for the 18-airgun 
array in water depth ranging from 200-5500 m. Received sound levels 
were predicted by L-DEO's model (Diebold et al., 2010) as a function of 
distance from L-DEO's full 36 airgun array (versus the smaller array 
planned for use here). Models for the 36-airgun array used a 12-m tow 
depth, versus the 6-m tow depth planned for this survey. 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 (~1600 m), 
intermediate water depth on the slope (~600-1100 m), and shallow water 
(~50 m) in the Gulf of Mexico in 2007-2008 (Tolstoy et al., 2009; 
Diebold et al., 2010).
    For deep and intermediate water cases, the field measurements 
cannot be used readily to derive the 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 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 Appendix H of the NSF-USGS PEIS). 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 Appendix H of the NSF-USGS PEIS). 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 survey will acquire data with the 18-airgun array at a tow 
depth of 6 m. For deep water (>1,000 m), we use the deep-water radii 
obtained from L-DEO model results down to a maximum water depth of 
2,000 m for the 18-airgun array. The radii for intermediate water 
depths (100-1,000 m) are derived from the deep-water ones by applying a 
correction factor (multiplication) of 1.5, such that observed levels at 
very near offsets fall below the corrected mitigation curve (see Figure 
16 in Appendix H of PEIS).
    L-DEO's modeling methodology is described in greater detail in the 
IHA 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  (in
                                                                                                     m) to the
            Airgun configuration             Tow depth  (m)            Water depth  (m)               level B
                                                                                                    harassment
                                                                                                     threshold
----------------------------------------------------------------------------------------------------------------
18 airguns, 3300 in \3\....................               6  >1000 m............................       \a\ 2,886
                                                             100-1000 m.........................       \b\ 4,329
----------------------------------------------------------------------------------------------------------------
\a\ Distance is based on L-DEO model results.
\b\ Distance is based on L-DEO model results with a 1.5 x correction factor between deep and intermediate water
  depths.

    Table 5 presents the modeled PTS isopleths for each marine mammal 
hearing group based on L-DEO modeling incorporated in the companion 
User Spreadsheet (NMFS 2018).

          Table 5--Modeled Radial Distance to Isopleths Corresponding to Level A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                                                        LF              MF              HF
----------------------------------------------------------------------------------------------------------------
PTS SELcum......................................................           101.9               0             0.5
PTS Peak........................................................            23.3            11.2           116.9
----------------------------------------------------------------------------------------------------------------
Note: The largest distance (in bold) of the dual criteria (Sound Exposure Level (SEL) cum or Peak) was used to
  estimate threshold distances and potential takes by Level A harassment.

    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal hearing groups, were calculated based on 
modeling performed by L-DEO using the Nucleus software program and the 
NMFS User Spreadsheet, described below. The acoustic thresholds for 
impulsive sounds (e.g., airguns) contained in the Technical Guidance 
were presented as dual metric acoustic thresholds using both 
SELcum and peak sound pressure

[[Page 30289]]

metrics (NMFS, 2016a). As dual metrics, NMFS considers onset of PTS 
(Level A harassment) to have occurred when either one of the two 
metrics is exceeded (i.e., metric resulting in the largest isopleth). 
The SELcum metric considers both level and duration of 
exposure, as well as auditory weighting functions by marine mammal 
hearing group. In recognition of the fact that the requirement to 
calculate Level A harassment ensonified areas could be more technically 
challenging to predict due to the duration component and the use of 
weighting functions in the new SELcum thresholds, NMFS 
developed an optional User Spreadsheet that includes tools to help 
predict a simple isopleth that can be used in conjunction with marine 
mammal density or occurrence to facilitate the estimation of take 
numbers.
    The SELcum for the 18-airgun array is derived from 
calculating the modified farfield signature. The farfield signature is 
often used as a theoretical representation of the source level. To 
compute the farfield signature, the source level is estimated at a 
large distance (right) below the array (e.g., 9 km), and this level is 
back projected mathematically to a notional distance of 1 m from the 
array's geometrical center. However, it has been recognized that the 
source level from the theoretical farfield signature is never 
physically achieved at the source when the source is an array of 
multiple airguns separated in space (Tolstoy et al., 2009). Near the 
source (at short ranges, distances <1 km), the pulses of sound pressure 
from each individual airgun in the source array do not stack 
constructively as they do for the theoretical farfield signature. The 
pulses from the different airguns spread out in time such that the 
source levels observed or modeled are the result of the summation of 
pulses from a few airguns, not the full array (Tolstoy et al., 2009). 
At larger distances, away from the source array center, sound pressure 
of all the airguns in the array stack coherently, but not within one 
time sample, resulting in smaller source levels (a few dB) than the 
source level derived from the farfield signature. Because the farfield 
signature does not take into account the large array effect near the 
source and is calculated as a point source, the farfield signature is 
not an appropriate measure of the sound source level for large arrays. 
See the 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, in context 
of distributed source dynamics. The source level of the array is a 
theoretical definition assuming a point source and measurement in the 
far-field of the source (MacGillivray, 2006). As described by Caldwell 
and Dragoset (2000), an array is not a point source, but one that spans 
a small area. In the far-field, individual elements in arrays will 
effectively work as one source because individual pressure peaks will 
have coalesced into one relatively broad pulse. The array can then be 
considered a ``point source.'' For distances within the near-field, 
i.e., approximately 2-3 times the array dimensions, pressure peaks from 
individual elements do not arrive simultaneously because the 
observation point is not equidistant from each element. The effect is 
destructive interference of the outputs of each element, so that peak 
pressures in the near-field will be significantly lower than the output 
of the largest individual element. Here, the relevant peak isopleth 
distances will in all cases be expected to be within the near-field of 
the array where the definition of source level breaks down. Therefore, 
actual locations within this distance of the array center where the 
sound level exceeds the relevant peak SPL thresholds would not 
necessarily exist. In general, Caldwell and Dragoset (2000) suggest 
that the near-field for airgun arrays is considered to extend out to 
approximately 250 m.
    In order to provide quantitative support for this theoretical 
argument, we calculated expected maximum distances at which the near-
field would transition to the farfield (Table 5). For a specific array, 
one can estimate the distance at which the near-field transitions to 
the farfield by:
[GRAPHIC] [TIFF OMITTED] TN11MY23.009

with the condition that D >> [lambda], and where D is the distance, L 
is the longest dimension of the array, and [lambda] is the wavelength 
of the signal (Lurton, 2002). Given that [lambda] can be defined by:
[GRAPHIC] [TIFF OMITTED] TN11MY23.010

where f is the frequency of the sound signal and v is the speed of the 
sound in the medium of interest, one can rewrite the equation for D as:
[GRAPHIC] [TIFF OMITTED] TN11MY23.011

and calculate D directly given a particular frequency and known speed 
of sound (here assumed to be 1,500 meters per second in water, although 
this varies with environmental conditions).
    To determine the closest distance to the arrays at which the source 
level predictions in Table 5 are valid (i.e., maximum extent of the 
near-field), we calculated D based on an assumed frequency of 1 kHz. A 
frequency of 1 kHz is commonly used in near-field/farfield calculations 
for airgun arrays (Zykov and Carr, 2014; MacGillivray, 2006; NSF and 
USGS, 2011), and based on representative airgun spectrum data and field 
measurements of an airgun array used on the Langseth, nearly all 
(greater than 95 percent) of the energy from airgun arrays is below 1 
kHz (Tolstoy et al., 2009). Thus, using 1 kHz as the upper cut-off for 
calculating the maximum extent of the near-field should reasonably 
represent the near-field extent in field conditions.
    If the largest distance to the peak sound pressure level threshold 
was equal to or less than the longest dimension of the array (i.e., 
under the array), or within the near-field, then received levels that 
meet or exceed the threshold in most cases are not expected to occur. 
This is because within the near-field and within the dimensions of the 
array, the source levels specified in Appendix A of L-DEO's application 
are overestimated and not applicable. In fact, until one reaches a 
distance of approximately three or four times the near-field distance, 
the average intensity of sound at any given distance from the array is 
still less than that based on calculations that assume a directional 
point source (Lurton, 2002). The 3,300-in\3\ airgun array planned for 
use during the survey has an approximate diagonal of 18.6 m, resulting 
in a near-field distance of approximately 58 m at 1 kHz (NSF and USGS, 
2011). Field measurements of this array indicate that the source 
behaves like multiple discrete sources, rather than a directional point 
source, beginning at approximately 400 m (deep site) to 1 km (shallow 
site) from the center of the array (Tolstoy et al., 2009), distances 
that are actually greater than four times the calculated 58-m near-
field distance. Within these distances, the recorded received levels 
were always lower than would be predicted based on calculations that 
assume a directional point source, and increasingly so as one moves 
closer towards the array (Tolstoy et al., 2009). Given this, relying on 
the calculated distance (58 m) as the distance at which we expect to be 
in the near-field is a conservative approach since even beyond this 
distance the acoustic modeling still overestimates

[[Page 30290]]

the actual received level. Within the near-field, in order to 
explicitly evaluate the likelihood of exceeding any particular acoustic 
threshold, one would need to consider the exact position of the animal, 
its relationship to individual array elements, and how the individual 
acoustic sources propagate and their acoustic fields interact. Given 
that within the near-field and dimensions of the array source levels 
will be below those assumed here, we believe exceedance of the peak 
pressure threshold will only be possible under highly unlikely 
circumstances.
    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 minimal, 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 low- or mid-frequency cetacean 
and do not propose to authorize any 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]Parms 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 that 
will inform the take calculations.
    Habitat-based density models produced by the Duke University Marine 
Geospatial Ecology Laboratory (Roberts et al., 2016; Roberts and 
Halpin, 2022) represent the best available information regarding marine 
mammal densities in the survey area. The density data presented by 
Roberts et al. (2016 and 2022) incorporates aerial and shipboard line-
transect survey data from NMFS and other organizations and incorporates 
data from 8 physiographic and 16 dynamic oceanographic and biological 
covariates, and controls for the influence of sea state, group size, 
availability bias, and perception bias on the probability of making a 
sighting. These density models were originally developed for all 
cetacean taxa in the U.S. Atlantic (Roberts et al., 2016). In 
subsequent years, certain models have been updated based on additional 
data as well as certain methodological improvements. More information 
is available online at https://seamap.env.duke.edu/models/Duke/EC/. 
Marine mammal density estimates in the survey area (animals/km\2\) were 
obtained using the most recent model results for all taxa (Roberts et 
al., 2016 and 2022).
    Monthly density grids (e.g., rasters) for each species were 
overlaid with the Survey Area and values from all grid cells that 
overlapped the Survey Area (plus a 40 km buffer) were averaged to 
determine monthly mean density values for each species. Monthly mean 
density values within the Survey Area were averaged for each of the two 
water depth categories (intermediate and deep) for the months May to 
October. The highest mean monthly density estimates for each species 
were used to estimate take.

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 is 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 planned 
line km to be surveyed. The highest mean monthly density for each 
species was then multiplied by the daily ensonified areas, increased by 
25 percent, and then multiplied by the number of survey days (28) 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 authorized take 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 planned 
for authorization. Estimated exposures and take numbers for 
authorization are shown in Table 6.

                                                        Table 6--Estimated Take for Authorization
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Estimated take                  Authorized take
            Species                    Stock       ----------------------------------------------------------------  Stock  abundance   Percent of stock
                                                        Level B         Level A         Level B         Level A
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale.....  Western North                0.03               0               0               0  368..............  n/a
                                  Atlantic.
Humpback whale.................  Gulf of Maine....            0.06               0           \1\ 2               0  1,396............  0.14
Fin whale......................  Western North                   4               0               4               0  6,802............  0.06
                                  Atlantic.
Sei whale......................  Nova Scotia......               8               0               8               0  6,292............  0.13
Minke whale....................  Canadian East                  10               0              10               0  21,968...........  0.05
                                  Coast.
Blue whale.....................  Western North                   1               0               1               0  402..............  0.17
                                  Atlantic.
Sperm whale....................  North Atlantic...             405               1             406               0  4,349............  9.34
Kogia spp......................  .................             678              31             678              31  15,500...........  0.04

[[Page 30291]]

 
Cuvier's beaked whale..........  Western North                 394               2             396               0  5,744............  6.89
                                  Atlantic.
Mesoplodont Beaked whales......  .................             418               2             420               0  30,321...........  1.38
Pilot whales...................  .................             384               1             385               0  15,500...........  2.48
Rough-toothed dolphin..........  Western North                  82               0              82               0  136..............  10.79
                                  Atlantic.
Bottlenose dolphin.............  Western North               1,473               4           1,477               0  62,851...........  2.35
                                  Atlantic
                                  Offshore.
Atlantic white-sided dolphin...  Western North                   0               0          \1\ 14               0  93,233...........  0.02
                                  Atlantic.
Pantropical spotted dolphin....  Western North                 114               0             114               0  6,593............  1.73
                                  Atlantic.
Atlantic spotted dolphin.......  Western North               1,232               5           1,237               0  39,921...........  3.1
                                  Atlantic.
Spinner dolphin................  Western North                  41               0              41               0  4,102............  1.00
                                  Atlantic.
Clymene dolphin................  Western North                  79               0              79               0  4,237............  1.87
                                  Atlantic.
Striped dolphin................  Western North                  19               0          \1\ 45               0  67,036...........  0.07
                                  Atlantic.
Fraser's dolphin...............  Western North                  62               0         \2\ 163               0  unk..............  .................
                                  Atlantic.
Risso's dolphin................  Western North                 189               0             189               0  35,215...........  0.54
                                  Atlantic.
Common dolphin.................  Western North                  56               0              56               0  172,947..........  11.99
                                  Atlantic.
Melon-headed whale.............  Western North                  58               0          \2\ 83               0  3,965............  2.15
                                  Atlantic.
Pygmy killer whale.............  Western North                   6               0               6               0  unk..............  .................
                                  Atlantic.
False killer whale.............  Western North                   1               0           \2\ 6               0  1,791............  0.34
                                  Atlantic.
Killer whale...................  Western North                   2               0           \1\ 4               0  unk..............  .................
                                  Atlantic.
Harbor porpoise................  Gulf of Maine/Bay            0.01               0           \1\ 3               0  95,543...........  0.00
                                  of Fundy.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Take increased to mean group size from the Atlantic Marine Assessment Program for Protected Species (AMAPPS; Palka et al., 2017 and 2021).
\2\ Take increased to mean group size from the Ocean Biodiversity Information System (OBIS 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, as 
well as subsistence uses. 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

[[Page 30292]]

also acts as an extension of the SZ in that observations of marine 
mammals within the buffer zone will also prevent airgun operations from 
beginning (i.e., ramp-up). The buffer zone encompasses the area at and 
below the sea surface from the edge of the 0-500 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, 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 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 
acoustic source is planned to occur, and whenever the acoustic source 
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 acoustic source 
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 acoustic source (rather than being based on the center of the array 
or around the vessel itself). During use of the acoustic source (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 acoustic source. 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 
acoustic source is not operating for comparison of sighting rates and 
behavior with and without use of the acoustic source and between 
acquisition periods, to the maximum extent practicable.
    Visual PSOs may be on watch for a maximum of 4 consecutive hours 
followed by a break of at least 1 hour between watches and may conduct 
a maximum of 12 hours of observation per 24-hour period. Combined 
observational duties (visual and acoustic but not at same time) may not 
exceed 12 hours per 24-hour period for any individual PSO.

Passive Acoustic Monitoring (PAM)

    Acoustic monitoring 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 will 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 will 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 will 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 acoustic 
source. 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 5 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 EZ 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 acoustic source, but without an 
operating PAM system, do not exceed a cumulative total of 5 hours in 
any 24-hour period.

[[Page 30293]]

Establishment of Shutdown and Pre-Start Clearance Zones

    An SZ is a defined area within which occurrence of a marine mammal 
triggers mitigation action intended to reduce the potential for certain 
outcomes, e.g., auditory injury, disruption of critical behaviors. The 
PSOs will establish a minimum SZ with a 500-m radius. The 500-m SZ will 
be based on radial distance from the edge of the airgun array (rather 
than being based on the center of the array or around the vessel 
itself). With certain exceptions (described below), if a marine mammal 
appears within or enters this zone, the acoustic source will be shut 
down.
    The pre-start clearance zone is defined as the area that must be 
clear of marine mammals prior to beginning ramp-up of the acoustic 
source, and includes the SZ plus the buffer zone. Detections of marine 
mammals within the pre-start clearance zone will prevent airgun 
operations from beginning (i.e., ramp-up).
    The 500-m SZ is intended to be precautionary in the sense that it 
will be expected to contain sound exceeding the injury criteria for all 
cetacean hearing groups, (based on the dual criteria of 
SELcum and peak SPL), while also providing a consistent, 
reasonably observable zone within which PSOs will typically be able to 
conduct effective observational effort. Additionally, a 500-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 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 must be enforced for all beaked whales 
and Kogia species. No buffer of this extended SZ is required.

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 protected 
species are observed within the pre-clearance zone (or extended SZ, for 
beaked whales and Kogia spp.) prior to the beginning of ramp-up. During 
pre-start clearance period is the only time observations of marine 
mammals in the buffer zone will 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 acoustic 
source. 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. Acoustic 
source activation may only occur at times of poor visibility where 
operational planning cannot reasonably avoid such circumstances;
     If the acoustic source is shut down for brief periods 
(i.e., less than 30 minutes) for reasons other than that described for 
shutdown (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 applicable SZ. For any longer shutdown, pre-start 
clearance observation and ramp-up are required. For any shutdown at 
night or in periods of poor visibility (e.g., BSS 4 or greater), ramp-
up is required, but if the shutdown period was brief and constant 
observation was maintained, pre-start clearance watch of 30 minutes is 
not required; and
     Testing of the acoustic source involving all elements 
requires ramp-up. Testing limited to individual source elements or 
strings does not require ramp-up but does require pre-start clearance 
of 30 min.

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 acoustic source 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 acoustic source 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

[[Page 30294]]

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 acoustic source will be shut down. When shutdown is called for by a 
PSO, the acoustic source 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 will be notified but 
shutdown is not required.
    Following a shutdown, airgun activity will not resume until the 
marine mammal has cleared the SZ. The animal will be considered to have 
cleared the SZ if it is visually observed to have departed the SZ 
(i.e., animal is not required to fully exit the buffer zone where 
applicable), or it has not been seen within the SZ for 15 minutes for 
small odontocetes, or 30 minutes for all mysticetes and all other 
odontocetes, including sperm whales, beaked whales, 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 will 
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 
in those delphinoids (e.g., Barkaszi et al., 2012, Barkaszi and Kelly, 
2018). The potential for increased shutdowns resulting from such a 
measure will 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 will 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 takes have been met, approaches the Level A or Level B 
harassment zones. L-DEO must also implement shutdown if any large whale 
(defined as a sperm whale or any mysticete species) with a calf 
(defined as an animal less than two-thirds the body size of an adult 
observed to be in close association with an adult) and/or an 
aggregation of six or more large whales are observed at any distance. 
Finally, L-DEO must implement shutdown upon detection (visual or 
acoustic) of a North Atlantic right whale at any distance.

Vessel Strike Avoidance

    Vessel operators and crews must maintain a vigilant watch for all 
protected species and slow down, stop their vessel, or alter course, as 
appropriate and regardless of vessel size, to avoid striking any marine 
mammal. 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 
identify a marine mammal as a whale or other marine mammal.
    Vessel speeds must be reduced to 10 kn 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 500 m 
from North Atlantic right whales and 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.
    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.
    All survey vessels, regardless of size, must observe a 10-kn speed 
restriction in specific areas designated by NMFS for the protection of 
North Atlantic right whales from vessel strikes. These include all 
Seasonal Management Areas (SMA) established under 50 CFR 224.105 (when 
in effect), any dynamic management areas (DMA) (when in effect), and 
Slow Zones. See www.fisheries.noaa.gov/national/endangered-species-
conservation/reducing-ship-strikes-north-atlantic-

[[Page 30295]]

right-whales for specific detail regarding these areas.

Operational Restrictions

    L-DEO must limit airgun use to between May 1 and October 31. Vessel 
movement and other activities that do not require use of airguns may 
occur outside of these dates. If any activities (non-seismic) are 
conducted between November 1 and April 30, daily PSO logs must be sent 
to the NOAA Southeast Regional Office (SERO). L-DEO must also notify 
SERO on the start and end date of seismic operations in the survey area 
via email ([email protected]).
    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 the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and,
     Mitigation and monitoring effectiveness.

Vessel-Based Visual Monitoring

    As described above, PSO observations will take place during daytime 
airgun operations. During seismic survey operations, at least five 
visual PSOs will be based aboard the Langseth. Two visual PSOs will 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 (i.e., Fujinon or equivalent) 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; and
     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 data 
collection forms, whether hard copy or electronic. PSOs shall record 
detailed information about any implementation of mitigation 
requirements, including the distance of animals to the acoustic source 
and description of specific actions that ensued, the behavior of the 
animal(s), any observed changes in behavior before and after 
implementation of mitigation, and if shutdown was implemented, the 
length of time before any subsequent ramp-up of the acoustic source. If 
required mitigation was not

[[Page 30296]]

implemented, PSOs should record a description of the circumstances. At 
a minimum, the following information must be recorded:
     Vessel names (source vessel and other vessels associated 
with survey) and call signs;
     PSO names and affiliations;
     Dates of departures and returns to port with port name;
     Date and participants of PSO briefings;
     Dates and times (Greenwich Mean Time) of survey effort and 
times corresponding with PSO effort;
     Vessel location (latitude/longitude) when survey effort 
began and ended and vessel location at beginning and end of visual PSO 
duty shifts;
     Vessel heading and speed at beginning and end of visual 
PSO duty shifts and upon any line change;
     Environmental conditions while on visual survey (at 
beginning and end of PSO shift and whenever conditions changed 
significantly), including BSS and any other relevant weather conditions 
including cloud cover, fog, sun glare, and overall visibility to the 
horizon;
     Factors that may have contributed to impaired observations 
during each PSO shift change or as needed as environmental conditions 
changed (e.g., vessel traffic, equipment malfunctions); and
     Survey activity information, such as acoustic source power 
output while in operation, number and volume of airguns operating in 
the array, tow depth of the array, and any other notes of significance 
(i.e., pre-start clearance, ramp-up, shutdown, testing, shooting, ramp-
up completion, end of operations, streamers, etc.).
    The following information should be recorded upon visual 
observation of any protected species:
     Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
     PSO who sighted the animal;
     Time of sighting;
     Vessel location at time of sighting;
     Water depth;
     Direction of vessel's travel (compass direction);
     Direction of animal's travel relative to the vessel;
     Pace of the animal;
     Estimated distance to the animal and its heading relative 
to vessel at initial sighting;
     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;
     Estimated number of animals (high/low/best);
     Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
     Description (as many distinguishing features as possible 
of each individual seen, including length, shape, color, pattern, scars 
or markings, shape and size of dorsal fin, shape of head, and blow 
characteristics);
     Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding, 
traveling; as explicit and detailed as possible; note any observed 
changes in behavior);
     Animal's closest point of approach (CPA) and/or closest 
distance from any element of the acoustic source;
     Platform activity at time of sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other); and
     Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up) and time and location of the 
action.
    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

    L-DEO must submit a draft comprehensive report to NMFS on all 
activities and monitoring results within 90 days of the completion of 
the survey or expiration of the IHA, whichever comes sooner. A final 
report must be submitted within 30 days following resolution of any 
comments on the draft report. The report will describe the operations 
that were conducted and sightings of marine mammals near the 
operations. The report will provide full documentation of methods, 
results, and interpretation pertaining to all monitoring. The 90-day 
report will summarize the dates and locations of seismic operations, 
and all marine mammal sightings (dates, times, locations, activities, 
associated seismic survey activities). The report will also include 
estimates of the number and nature of exposures that occurred above the 
harassment threshold based on PSO observations and including an 
estimate of those that were not detected, in consideration of both the 
characteristics and behaviors of the species of marine mammals that 
affect detectability, as well as the environmental factors that affect 
detectability.
    The draft report shall also include geo-referenced time-stamped 
vessel tracklines for all time periods during which airguns were 
operating. Tracklines should include points recording any change in 
airgun status (e.g., when the airguns began operating, when they were 
turned off, or when they changed from full array to single gun or vice 
versa). Geographic Information Systems (GIS) files shall be provided in 
Environmental Systems Research Institute (ESRI) shapefile format and 
include the UTC date and time, latitude in decimal degrees, and 
longitude in decimal degrees. All coordinates shall be referenced to 
the WGS84 geographic coordinate system. In addition to the report, all 
raw observational data shall be made available to NMFS. A final report 
must be submitted within 30 days following resolution of any comments 
on the draft report.

Reporting Species of Concern

    Although not anticipated, if a North Atlantic right whale is 
observed at any time by PSOs or personnel on any project vessels, 
during surveys or during vessel transit, L-DEO must immediately report 
sighting information to the NMFS North Atlantic Right Whale Sighting 
Advisory System: 877-WHALE-HELP (877-942-5343). North Atlantic right 
whale sightings in any location must also be reported to the U.S. Coast 
Guard via channel 16.

Reporting Injured or Dead Marine Mammals

    Discovery of injured or dead marine mammals--In the event that 
personnel involved in survey activities covered by the authorization 
discover an injured or dead marine mammal, the L-DEO shall report the 
incident to the Office of Protected Resources (OPR), NMFS and to the 
NMFS South East 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);

[[Page 30297]]

     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 ship 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 South East 
Regional Stranding Coordinator as soon as feasible. The report must 
include the following information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Vessel's speed during and leading up to the incident;
     Vessel's course/heading and what operations were being 
conducted (if applicable);
     Status of all sound sources in use;
     Description of avoidance measures/requirements that were 
in place at the time of the strike and what additional measure were 
taken, if any, to avoid strike;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
     Species identification (if known) or description of the 
animal(s) involved;
     Estimated size and length of the animal that was struck;
     Description of the behavior of the animal immediately 
preceding and following the strike;
     If available, description of the presence and behavior of 
any other marine mammals present immediately preceding the strike;
     Estimated fate of the animal (e.g., dead, injured but 
alive, injured and moving, blood or tissue observed in the water, 
status unknown, disappeared); and
     To the extent practicable, photographs or video footage of 
the animal(s).

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 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 acoustic 
sources 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 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 will 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 potential 
takes will be in the form of short-term Level B behavioral harassment 
in the form of temporary avoidance of the area or decreased foraging 
(if such activity was occurring), reactions that are considered to be 
of low severity and with no lasting biological consequences (e.g., 
Southall et al., 2007). Even repeated Level B harassment of some small 
subset of an overall stock is unlikely to result in any significant 
realized decrease in viability for the affected individuals, and thus 
will not result in any adverse impact to the stock as a whole.
    We authorized a limited number of instances of Level A harassment 
of two species (pygmy and dwarf sperm

[[Page 30298]]

whales, which are members of the high-frequency cetacean hearing group) 
in the form of PTS, and Level B harassment only of the remaining marine 
mammal species. Any PTS incurred in marine mammals as a result of the 
activity is expected to be in the form of a small degree of PTS, and 
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 will be expected to 
concentrate for an extended period of time. Additionally, L-DEO will 
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 will 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. Accordingly, we expect that the majority of 
takes will be in the form of short-term Level B behavioral harassment 
in the form of temporary avoidance of the area or decreased foraging 
(if such activity were occurring), reactions that are considered to be 
of low severity and with no lasting biological consequences (e.g., 
Southall et al., 2007; Ellison et al., 2012).
    In addition to being temporary, the maximum expected Level B 
harassment zone around the survey vessel is 2,886 m for water depths 
greater than 1,000 m (and up to 4,329 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 
(28 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.
    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 will 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. No Level A harassment is 
anticipated, even in the absence of mitigation measures, or authorized 
for species with active UMEs.
    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 
(28 days);
     The anticipated impacts of the activity on marine mammals 
will 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 
will be temporary and spatially limited, and impacts to marine mammal 
foraging will 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 small numbers of incidental take may be 
authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such

[[Page 30299]]

as the temporal or spatial scale of the activities.
    The amount of take NMFS authorized is below one third of the 
estimated stock abundance for all species with available abundance 
estimates (in fact, take of individuals is less than fifteen 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 will count them as 
separate individuals if they cannot be identified.
    NMFS considers it appropriate to make a small numbers finding in 
the case of a species or stock that may potentially be taken but is 
either rarely encountered or only expected to be taken on rare 
occasions. In that circumstance, one or two assumed encounters with a 
group of animals (meaning a group that is traveling together or 
aggregated, and thus exposed to a stressor at the same approximate 
time) should reasonably be considered small numbers, regardless of 
consideration of the proportion of the stock (if known), as rare 
encounters resulting in take of one or two groups should be considered 
small relative to the range and distribution of any stock. In this 
case, NMFS authorized take resulting from a single exposure of one 
group each for Fraser's dolphin and killer whale (using average group 
size), and find that a single incident of take of one group of either 
of these species represents take of small numbers for that species.
    For pygmy killer whale, we authorized six incidents of take by 
Level B harassment. No abundance information is available for this 
species in the survey area. Therefore, we refer to other SAR abundance 
estimates for the species. NMFS estimates that the Hawaii stock of 
pygmy killer whales has a minimum abundance estimate of 5,885 whales 
(Carretta et al., 2020). In the Gulf of Mexico, NMFS estimates a 
minimum abundance of 613 whales for that stock (Hayes et al., 2020). 
Therefore, NMFS assumes that the estimated take number of six would be 
small relative to any reasonable estimate of population abundance for 
the species in the Atlantic.
    Based on the analysis contained herein of the 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 will not 
have an unmitigable adverse impact on the availability of such species 
or stocks for taking for subsistence purposes.

Endangered Species Act

    Section 7(a)(2) of the 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' Office of Protected Resources (OPR).
    The NMFS Office of Protected Resources 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 North Atlantic right whales, blue whales, fin 
whales, sei whales, and sperm whales.

National Environmental Policy Act

    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 
National Science Foundation 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 North 
Carolina. 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 CEQ 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). NSF's EA is available at https://www.nsf.gov/geo/oce/envcomp/north-carolina-2023/LDEO-NC-EA-7-Oct2022.pdf.

Authorization

    NMFS has issued an IHA to L-DEO for the potential harassment of 
small numbers of 30 marine mammal species incidental to a marine 
geophysical survey off North Carolina in the Northwest Atlantic Ocean 
that includes the previously explained mitigation, monitoring and 
reporting requirements.

    Dated: May 5, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-10024 Filed 5-10-23; 8:45 am]
BILLING CODE 3510-22-P