Notice2023-14946
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey of the Blake Plateau in the Northwest Atlantic Ocean
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
July 14, 2023
Effective
July 10, 2023
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
In accordance with the regulations implementing the Marine Mammal Protection Act (MMPA) as amended, notification is hereby given that NMFS has issued an incidental harassment authorization (IHA) to Lamont-Doherty Earth Observatory (L-DEO) to incidentally harass marine mammals during a marine geophysical survey of the Blake Plateau in the northwest Atlantic Ocean.
Full Text
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<title>Federal Register, Volume 88 Issue 134 (Friday, July 14, 2023)</title>
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[Federal Register Volume 88, Number 134 (Friday, July 14, 2023)]
[Notices]
[Pages 45172-45190]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-14946]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XD119]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to a Marine Geophysical Survey of the
Blake Plateau 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 a marine geophysical survey of the Blake Plateau in the
northwest Atlantic Ocean.
DATES: This authorization is effective from July 10, 2023 through July
9, 2024.
ADDRESSES: Electronic copies of the application and supporting
documents, as well as a list of the references cited in this document,
may be obtained online at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-lamont-doherty-earth-observatorys-marine-geophysical-surveys">https://www.fisheries.noaa.gov/action/incidental-take-authorization-lamont-doherty-earth-observatorys-marine-geophysical-surveys</a>. In case of problems accessing these documents,
please call the contact listed below.
FOR FURTHER INFORMATION CONTACT: Jenna Harlacher, Office of Protected
Resources (OPR) NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and either regulations
are proposed or, if the taking is limited to harassment, a notice of a
proposed IHA is provided to the public for review.
[[Page 45173]]
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 November 22, 2022, NMFS received a request from L-DEO for an IHA
to take marine mammals incidental to a marine geophysical survey of the
Blake Plateau in the northwest Atlantic Ocean. The application was
deemed adequate and complete on February 1, 2023. L-DEO's request is
for take of 29 marine mammal species by Level B harassment, and for 4
of these species, by Level A harassment. Neither L-DEO nor NMFS expect
serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.
Description of Activity
Overview
Researchers from the University of Texas Institute of Geophysics
(UTIG) and L-DEO, with funding from the National Science Foundation
(NSF), plan 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 surveys would occur in the Blake
Plateau in the northwest Atlantic Ocean during summer or fall 2023. The
planned multi-channel seismic (MCS) reflection and Ocean Bottom
Seismometers (OBS) seismic refraction surveys would occur within the
Exclusive Economic Zone (EEZ) of the United States and Bahamas and in
international waters, in depths ranging from >100 to 5,200 meters (m).
To complete this survey, the R/V Langseth would tow a 36-airgun
array consisting of a mixture of Bolt airguns ranging from 40 to 360
cubic inches (in\3\) (1-9.1 m\3\) each on four strings spaced 16 m
apart, with a total discharge volume of 6,600 in\3\ (167.6 m\3\). The
airgun array would be towed at 10-12 m deep along the survey lines,
while the receiving systems for the different survey segments would
consist of a 15 kilometer (km) long solid-state hydrophone streamer and
approximately 40 OBS, respectively. The airguns would fire at a shot
interval of 50 m (~24 seconds (s)) during multi-channel seismic (MCS)
reflection surveys with the hydrophone streamer and at a 200-m (~78 s)
interval during Ocean Bottom Seismometer (OBS) seismic refraction
surveys. Approximately 6682 kilometers (km) of seismic acquisition are
planned: 5730 km of 2D MCS seismic reflection data and 952 km of OBS
refraction data.
The study would acquire two-dimensional (2-D) seismic reflection
and seismic refraction data to examine the structure and evolution of
the rifted margins of the southeastern United States, including the
rift dynamics during the formation of the Carolina Trough and Blake
Plateau. Additional data would be collected using a multibeam
echosounder (MBES), a sub-bottom profiler (SBP), and an Acoustic
Doppler Current Profiler (ADCP), which would be operated from R/V
Langseth continuously during the seismic surveys, including during
transit. No take of marine mammals is expected to result from use of
this equipment.
Dates and Duration
The survey is planned to last for approximately 61 days, spread
between two operational legs, with 40 days of seismic operations. One
leg would include 32 days of MCS seismic operations and 4 days of
transit time, whereas the other leg would consist of 8 days of seismic
operations with OBSs, 13 days of OBS deployment, and 4 days of transit.
R/V Langseth would likely leave from and return to port in
Jacksonville, Florida during summer or fall 2023.
Specific Geographic Region
The survey would occur within approximately 27.5-33.5[deg] N, 74-
80[deg] W off the coasts of South Carolina to northern Florida in the
northwest Atlantic Ocean. The distances to all state waters would be
>80 km, and to the coast would be ~90 km off Georgia, ~98 km off
Florida, and ~107 km off South 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 EEZs of the United States and
Bahamas and in international waters, in depths ranging from >100 to
5,200 m deep.
[[Page 45174]]
[GRAPHIC] [TIFF OMITTED] TN14JY23.003
Figure 1--Location of the Blake Plateau Seismic Surveys in the
Northwest Atlantic Ocean
Representative survey tracklines are included in the figure; however,
the tracklines could occur anywhere within the survey area. MPA =
marine protected area; NMS = National Marine Sanctuary. EBSA =
Ecologically or Biologically Significant Marine Areas. CBD = Convention
on Biological Diversity. N = North.
A detailed description of the planned geophysical survey was
provided in the Federal Register notice of the proposed IHA (88 FR
37390; June 7, 2023). Since that time, no changes have been made to the
planned survey activities. Therefore, a detailed description is not
provided here. Please refer to that Federal Register notice for the
description of the specified activity.
Comments and Responses
A notice of NMFS' proposal to issue an IHA to L-DEO was published
in the Federal Register on June 7, 2023 (88 FR 37390), beginning a 30-
day comment period. That notice described, in detail, L-DEO's
activities, the marine mammal species that may be affected by the
activities, and the anticipated effects on marine mammals. In that
notice, we requested public input on the request for authorization
described therein, our analyses, the proposed authorization, and any
other aspect of the notice of proposed IHA, and requested that
interested persons submit relevant information, suggestions, and
comments. NMFS received no relevant or substantive 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, including correction of typographical
errors in the draft IHA and the Federal Register notice of proposed
IHA. Additionally, language has been added to the reporting requirement
clarifying that if no comments are received from NMFS within 30 days of
receiving the draft that the report is considered final. Finally, the
FRN was updated to note the correct period of time that airgun
operations can continue while there is a PAM malfunction (10 hours), as
was stated in the draft IHA provided for public review.
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. NMFS fully considered all of this information, and we refer
the reader to these descriptions, instead of reprinting the
information. Additional information regarding population trends and
threats may be found in NMFS' Stock Assessment Reports (SARs;
<a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and more general information about these species
(e.g., physical and behavioral descriptions) may be found on NMFS'
website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>). NMFS refers the
reader to the application and to the aforementioned sources for general
information regarding the species listed in Table 1.
Table 1 lists all species or stocks for which take is expected and
authorized for this activity, and summarizes information related to the
population or stock, including regulatory status under the MMPA and
Endangered Species Act (ESA) and potential biological removal (PBR),
where known. PBR is defined by the MMPA as the maximum number of
animals, not including natural mortalities, that may be removed from a
marine mammal stock while allowing
[[Page 45175]]
that stock to reach or maintain its optimum sustainable population (as
described in NMFS' SARs). While no serious injury or mortality is
anticipated or authorized here, PBR and annual serious injury and
mortality from anthropogenic sources are included here as gross
indicators of the status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS' stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprises that stock. For some species, this geographic area may extend
beyond U.S. waters. All 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: <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>.
Table 1--Species Likely Impacted by the Specified Activities
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ESA/MMPA status; Stock abundance (CV, Modeled Annual
Common name Scientific name Stock Strategic (Y/N) Nmin, most recent abundance PBR M/SI
\1\ abundance survey) \2\ \5\ \3\
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Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family Balaenopteridae (rorquals):
Humpback whale................ Megaptera Gulf of Maine........ -/-; N 1,396 (0; 1,380; \7\ 2,259 22 12.15
novaeangliae. 2016).
Fin whale..................... Balaenoptera physalus Western North E/D; Y 6,802 (0.24; 5,573; \6\ 3,587 11 1.8
Atlantic. 2016).
Sei whale..................... Balaenoptera borealis Nova Scotia.......... E/D; Y 6,292 (1.02; 3,098; \6\ 1,043 6.2 0.8
2016).
Minke whale................... Balaenoptera Canadian East Coast.. -/-; N 21,968 (0.31; 17,002; \6\ 4,044 170 10.6
acutorostrata. 2016).
Blue whale.................... Balaenoptera musculus Western North E/D; Y unk (unk; 402; 1980- \7\ 33 0.8 0
Atlantic. 2008).
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Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family Physeteridae:
Sperm whale................... Physeter North Atlantic....... E/D; Y 4,349 (0.28; 3,451; \6\ 6,576 3.9 0
macrocephalus. 2016).
Family Kogiidae:
Pygmy sperm whale............. Kogia breviceps...... Western North -/-; N 7,750 (0.38; 5,689; \7\ 7,980 46 0
Atlantic. 2016).
Dwarf sperm whale............. Kogia sima........... Western North -/-; N
Atlantic.
Family Ziphiidae (beaked whales):
Cuvier's beaked Whale......... Ziphius cavirostris.. Western North -/-; N 5,744 (0.36, 4,282, \7\ 5,588 43 0.2
Atlantic. 2016).
Blainville's beaked Whale..... Mesoplodon Western North -/-; N 10,107 (0.27; 8,085; \7\ 6,526 \4\ 81 \4\ 0
densirostris. Atlantic. 2016) \4\.
True's beaked whale........... Mesoplodon mirus..... Western North -/-; N
Atlantic.
Gervais' beaked whale......... Mesoplodon europaeus. Western North -/-; N
Atlantic.
Family Delphinidae:
Long-finned pilot whale....... Globicephala melas... Western North -/-; N 39,215 (0.30; 30,627; \7\ \8\ 306 9
Atlantic. 2016). 23,905
Short finned pilot whale...... Globicephala Western North -/-; Y 28,924 (0.24; 23,637; 236 136
macrorhynchus. Atlantic. 2016).
Rough-toothed dolphin......... Steno bredanensis.... Western North -/-; N 136 (1.0; 67; 2016).. \7\ 1,011 0.7 0
Atlantic.
Bottlenose dolphin............ Tursiops truncatus... Western North -/-; N 62,851 (0.23; 51,914, \6\ 68,739 519 28
Atlantic Offshore. 2016).
Pantropical spotted dolphin... Stenella attenuata... Western North -/-; N 6,593 (0.52; 4,367; \7\ 1,403 44 0
Atlantic. 2016).
Atlantic spotted dolphin...... Stenella frontalis... Western North -/-; N 39,921 (0.27; 32,032; \6\ 39,352 320 0
Atlantic. 2016).
Spinner dolphin............... Stenella longirostris Western North -/-; N 4,102 (0.99; 2,045; \7\ 885 21 0
Atlantic. 2016).
Clymene dolphin............... Stenella clymene..... Western North -/-; N 4,237 (1.03; 2,071; \7\ 8,576 21 0
Atlantic. 2016).
Striped dolphin............... Stenella coeruleoalba Western North -/-; N 67,036 (0.29; 52,939; \7\ 54,707 529 0
Atlantic. 2016).
Fraser's dolphin.............. Lagenodelphis hosei.. Western North -/-; N unk.................. \7\ 658 unk 0
Atlantic.
Risso's dolphin............... Grampus griseus...... Western North -/-; N 35,215(0.19; 30,051; \6\ 24,260 301 34
Atlantic. 2016).
Common dolphin................ Delphinus delphis.... Western North -/-; N 172,947 (0.21; \6\ 144,036 1,452 390
Atlantic. 145,216; 2016).
Melon-headed whale............ Peponocephala electra Western North -/-; N unk.................. \7\ 618 unk 0
Atlantic.
Pygmy killer whale............ Feresa attenuate..... Western North -/-; N unk.................. \7\ 68 unk 0
Atlantic.
False killer whale............ Pseudorca crassidens. Western North -/-; N 1,791 (0.56; 1,154; \7\ 139 12 0
Atlantic. 2016).
Killer whale.................. Orcinus orca......... Western North -/-; N unk.................. \7\ 73 unk 0
Atlantic.
Family Phocoenidae (porpoises):
[[Page 45176]]
Harbor porpoise............... Phocoena phocoena.... Gulf of Maine/Bay of -/-; N 95,543 (0.31; 74,034; \6\ 55,049 851 164
Fundy. 2016).
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\1\ ESA status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or
designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or
which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is
automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region/">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region/</a>. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance; unknown (unk).
\3\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial
fisheries, ship strike). Annual mortality or serious injury (M/SI) often cannot be determined precisely and is in some cases presented as a minimum
value or range.
\4\ The values for Mesoplodont beaked whales would also represent Sowerby's beaked whales, which are not expected to occur in the survey area.
\5\ Modeled abundance from Roberts et al. (2023).
\6\ Averaged monthly (May-Oct) abundance.
\7\ Only single annual abundance given.
\8\ Modeled abundance for pilot whale is grouped together for both short-finned and long-finned pilot whales.
As indicated above, all 29 species in Table 1 temporally and
spatially co-occur with the activity to the degree that take is
reasonably likely to occur. Species that could potentially occur in the
research area but are not likely to be harassed due to the rarity of
their occurrence (i.e., are considered extralimital or rare visitors to
the waters of the northwest Atlantic Ocean), or because their known
migration through the area does not align with the survey dates, were
omitted.
A detailed description of the of the species likely to be affected
by the geophysical survey, including brief introductions to the species
and relevant stocks as well as available information regarding
population trends and threats, and information regarding local
occurrence, were provided in the Federal Register notice for the
proposed IHA (88 FR 37390, June 7, 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 (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>) 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 (LF) 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 LF cetaceans where the lower bound
was deemed to be biologically implausible and the lower bound from
Southall et al. (2007) retained. Marine mammal hearing groups and their
associated hearing ranges are provided in Table 2.
Table 2--Marine Mammal Hearing Groups
[NMFS, 2018]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans (dolphins, 150 Hz to 160 kHz.
toothed whales, beaked whales, bottlenose
whales).
High-frequency (HF) cetaceans (true 275 Hz to 160 kHz.
porpoises, Kogia, river dolphins,
Cephalorhynchid, Lagenorhynchus cruciger &
L. australis).
Phocid pinnipeds (PW) (underwater) (true 50 Hz to 86 kHz.
seals).
Otariid pinnipeds (OW) (underwater) (sea 60 Hz to 39 kHz.
lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on ~65 dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al., 2007) and PW pinniped (approximation).
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 37390, June 7,
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
[[Page 45177]]
proposed IHA (88 FR 37390, June 7, 2023).
Estimated Take of Marine Mammals
This section provides an estimate of the number of incidental takes
authorized through the IHA, which will inform both NMFS' consideration
of ``small numbers,'' and the negligible impact determinations.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Anticipated takes would primarily be Level B harassment, as use of
the airgun arrays have the potential to result in disruption of
behavioral patterns of marine mammals. There is also some potential for
auditory injury (Level A harassment) to result for species of certain
hearing groups due to the size of the predicted auditory injury zones
for those groups. Auditory injury is less likely to occur for MF
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 HF cetaceans. As discussed in further detail below, we do not expect
auditory injury for MF 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 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 planned survey includes the use of impulsive seismic
sources (e.g., Bolt 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 planned 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:
<a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance</a>.
Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
PTS onset acoustic thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 219 dB; Cell 2: LE,LF,24h: 199 dB
LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans........... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,MF,24h: 198 dB
LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.......... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,HF,24h: 173 dB
LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 218 dB; Cell 8: LE,PW,24h: 201 dB
LE,PW,24h: 185 dB.
[[Page 45178]]
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 232 dB; Cell 10: LE,OW,24h: 219 dB
LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as
incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript
``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted within the
generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates
the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds)
and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could
be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible,
it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that are used in estimating the area ensonified above the
acoustic thresholds, including source levels and transmission loss
coefficient.
When the NMFS Technical Guidance (2016a) 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 when more sophisticated 3D
modeling methods are not available, and NMFS continues to develop ways
to quantitatively refine these tools, and will qualitatively address
the output where appropriate.
The planned survey would entail the use of a 36-airgun array with a
total discharge volume of 6,600 in\3\ at a tow depth of 10-12 m. L-
DEO's model results are used to determine the 160 dBrms radius for the
36-airgun array in water depth ranging from >100 to 5,200 m. Received
sound levels have been predicted by L-DEO's model (Diebold et al.,
2010) as a function of distance from the 36-airgun array. Models for
the 36-airgun array used a 12-m tow depth. 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 (~600-1,100 m), and shallow water
(~50 m) in the Gulf of Mexico (Tolstoy et al., 2009; Diebold et al.,
2010).
For deep and intermediate water cases, the field measurements
cannot be used readily to derive the harassment isopleths, as at those
sites the calibration hydrophone was located at a roughly constant
depth of 350-550 m, which may not intersect all the SPL isopleths at
their widest point from the sea surface down to the assumed maximum
relevant water depth (~2,000 m) for marine mammals. At short ranges,
where the direct arrivals dominate and the effects of seafloor
interactions are minimal, the data at the deep sites are suitable for
comparison with modeled levels at the depth of the calibration
hydrophone. At longer ranges, the comparison with the model--
constructed from the maximum SPL through the entire water column at
varying distances from the airgun array--is the most relevant.
In deep and intermediate water depths at short ranges, sound levels
for direct arrivals recorded by the calibration hydrophone and L-DEO
model results for the same array tow depth are in good alignment (see
Figures 12 and 14 in Diebold et al., 2010). Consequently, isopleths
falling within this domain can be predicted reliably by the L-DEO
model, although they may be imperfectly sampled by measurements
recorded at a single depth. At greater distances, the calibration data
show that seafloor-reflected and sub-seafloor-refracted arrivals
dominate, whereas the direct arrivals become weak and/or incoherent
(see Figures 11, 12, and 16 in Diebold et al., 2010). Aside from local
topography effects, the region around the critical distance is where
the observed levels rise closest to the model curve. However, the
observed sound levels are found to fall almost entirely below the model
curve. Thus, analysis of the Gulf of Mexico calibration measurements
demonstrates that although simple, the L-DEO model is a robust tool for
conservatively estimating isopleths.
The survey would acquire data with the 36-airgun array at a tow
depth of 10-12 m. For deep water (gt;1000 m), we use the deep-water
radii obtained from L-DEO model results down to a maximum water depth
of 2,000 m for the 36-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 Diebold et al., 2010).
L-DEO's modeling methodology is described in greater detail in L-
DEO's application. The estimated distances to the Level B harassment
isopleth for the airgun configuration are shown in Table 4.
[[Page 45179]]
Table 4--Predicted Radial Distances From the R/V Langseth Seismic Source to Isopleth Corresponding to Level B
Harassment Threshold
----------------------------------------------------------------------------------------------------------------
Predicted
distances (in m)
Airgun configuration Tow depth (m) Water depth (m) to the Level B
harassment
threshold
----------------------------------------------------------------------------------------------------------------
4 strings, 36 airguns, 6,600 in\3\........................ 12 >1,000 \1\ 6,733
100-1,000 \2\ 10,100
----------------------------------------------------------------------------------------------------------------
\1\ Distance is based on L-DEO model results.
\2\ Distance is based on L-DEO model results with a 1.5 x correction factor between deep and intermediate water
depths.
Table 5 presents the modeled PTS isopleths for each cetacean
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
----------------------------------------------------------------------------------------------------------------
Low frequency Mid frequency High frequency
----------------------------------------------------------------------------------------------------------------
MCS Surveys
----------------------------------------------------------------------------------------------------------------
PTS SELcum............................................. 320.2 0 1
PTS Peak............................................... 38.9 13.6 268.3
----------------------------------------------------------------------------------------------------------------
OBS Surveys
----------------------------------------------------------------------------------------------------------------
PTS SELcum............................................. 80 0 0.3
PTS Peak............................................... 38.9 13.6 268.3
----------------------------------------------------------------------------------------------------------------
The largest distance (in bold) of the dual criteria (SELcum or Peak) was used to estimate threshold distances
and potential takes by Level A harassment.
Predicted distances to Level A harassment isopleths, which vary
based on marine mammal hearing groups, were calculated based on
modeling performed by L-DEO using the Nucleus software program and the
NMFS user spreadsheet, described below. The acoustic thresholds for
impulsive sounds (e.g., airguns) contained in the NMFS Technical
Guidance were presented as dual metric acoustic thresholds using both
SEL<INF>cum</INF> and peak sound pressure metrics (NMFS 2016a). As dual
metrics, NMFS considers onset of PTS (Level A harassment) to have
occurred when either one of the two metrics is exceeded (i.e., metric
resulting in the largest isopleth). The SEL<INF>cum</INF> metric
considers both level and duration of exposure, as well as auditory
weighting functions by marine mammal hearing group. In recognition of
the fact that the requirement to calculate Level A harassment
ensonified areas could be more technically challenging to predict due
to the duration component and the use of weighting functions in the new
SEL<INF>cum</INF> thresholds, NMFS developed an optional user
spreadsheet that includes tools to help predict a simple isopleth that
can be used in conjunction with marine mammal density or occurrence to
facilitate the estimation of take numbers.
The SEL<INF>cum</INF> for the 36-airgun array is derived from
calculating the modified farfield signature. The farfield signature is
often used as a theoretical representation of the source level. To
compute the farfield signature, the source level is estimated at a
large distance (right) below the array (e.g., 9 km), and this level is
back projected mathematically to a notional distance of 1 m from the
array's geometrical center. However, it has been recognized that the
source level from the theoretical farfield signature is never
physically achieved at the source when the source is an array of
multiple airguns separated in space (Tolstoy et al., 2009). Near the
source (at short ranges, distances <1 km), the pulses of sound pressure
from each individual airgun in the source array do not stack
constructively as they do for the theoretical farfield signature. The
pulses from the different airguns spread out in time such that the
source levels observed or modeled are the result of the summation of
pulses from a few airguns, not the full array (Tolstoy et al., 2009).
At larger distances, away from the source array center, sound pressure
of all the airguns in the array stack coherently, but not within one
time sample, resulting in smaller source levels (a few dB) than the
source level derived from the far-field signature. Because the far-
field signature does not take into account the large array effect near
the source and is calculated as a point source, the far-field signature
is not an appropriate measure of the sound source level for large
arrays. See L-DEO's application for further detail on acoustic
modeling.
Auditory injury is unlikely to occur for MF cetaceans, given very
small modeled zones of injury for those species (all estimated zones
less than 15 m for MF cetaceans), 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 two
to three times the array dimensions, pressure peaks from individual
elements do not arrive simultaneously because the observation point is
not
[[Page 45180]]
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 would 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 far-field (Table 5). For a specific array
one can estimate the distance at which the near-field transitions to
the far-field by:
[GRAPHIC] [TIFF OMITTED] TN14JY23.004
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] TN14JY23.005
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] TN14JY23.006
and calculate D directly given a particular frequency and known speed
of sound (here assumed to be 1,500 m 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/far-field
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 6,600-in\3\ airgun array planned for
use during the survey has an approximate diagonal of 28.8 m, resulting
in a near-field distance of approximately 138.7 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 138.7-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 (138.7 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 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 would be below
those assumed here, we believe exceedance of the peak pressure
threshold would 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 MF
cetaceans to be de minimis, even before the likely moderating effects
of aversion and/or other compensatory behaviors (e.g., Nachtigall et
al., 2018) are considered. We do not believe that Level A harassment is
a likely outcome for any MF cetacean and are not authorizing any take
by Level A harassment for these species.
The Level A and Level B harassment estimates are based on a
consideration of the number of marine mammals that could be within the
area around the operating airgun array where received levels of sound
>=160 dB re 1 [micro]Pa RMS are predicted to occur (see Table 1). The
estimated numbers are based on the densities (numbers per unit area) of
marine mammals expected to occur in the area in the absence of seismic
surveys. To the extent that marine mammals tend to move away from
seismic sources before the sound level reaches the criterion level and
tend not to approach an operating airgun array, these estimates likely
overestimate the numbers actually exposed to the specified level of
sound.
Marine Mammal Occurrence
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations.
Habitat-based density models produced by the Duke University Marine
Geospatial Ecology Laboratory (Roberts et al., 2016; Roberts et al.,
2023) represent the best available information regarding marine mammal
densities in the survey area. This density information 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 <a href="https://seamap.env.duke.edu/models/Duke/EC/">https://seamap.env.duke.edu/models/Duke/EC/</a>. Marine mammal density estimates in the survey area (animals/
km\2\) were obtained using the most recent model results for all taxa.
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
[[Page 45181]]
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 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 as
described above), and then multiplied by the number of survey days (40)
to estimate potential takes (see Appendix B of L-DEO's application for
more information).
L-DEO generally assumed that their estimates of marine mammal
exposures above harassment thresholds equate to take and requested
authorization of those takes. Those estimates in turn form the basis
for our take authorization numbers. For the species for which NMFS does
not expect there to be a reasonable potential for take by Level A
harassment to occur, i.e., MF cetaceans, we have added L-DEO's
estimated exposures above Level A harassment thresholds to their
estimated exposures above the Level B harassment threshold to produce a
total number of incidents of take by Level B harassment that is
authorized. Estimated exposures and take numbers for authorization are
shown in Table 6. As requested by L-DEO with NMFS concurrence, when
zero take was calculated we have authorized one group size of take as a
precaution since the species could potentially occur in the survey
area.
Table 6--Estimated Take for Authorization
--------------------------------------------------------------------------------------------------------------------------------------------------------
Estimated take Authorized take
Species Stock ---------------------------------------------------- Abundance \3\ Percent of
Level B Level A Level B Level A Stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale.............. Western North Atlantic.... 0 0 0 0 \4\ 338 n/a
Humpback whale.......................... Gulf of Maine............. 0 0 \1\ 2 0 \6\ 2,259 <0.1
Fin whale............................... Western North Atlantic.... 5 0 5 0 \5\ 3,587 0.1
Sei whale............................... Nova Scotia............... 28 2 28 2 \5\ 1,043 2.9
Minke whale............................. Canadian East Coast....... 20 1 20 1 \5\ 4,044 0.5
Blue whale.............................. Western North Atlantic.... 2 0 2 0 \6\ 33 6.1
Sperm whale............................. North Atlantic............ 706 3 709 0 \5\ 6,576 9.3
Kogia spp............................... .......................... 601 50 601 50 \6\ 7,980 8.2
Cuvier's beaked whale................... Western North Atlantic.... 365 1 366 0 \6\ 5,588 6.5
Mesoplodont beaked whales............... .......................... 154 1 155 0 \6\ 6,526 2.4
Pilot whales............................ .......................... 1,424 4 1,428 0 \6\ 23,905 6
Rough-toothed dolphin................... Western North Atlantic.... 301 1 302 0 \6\ 1,011 30
Bottlenose dolphin...................... Western North Atlantic 4,445 12 4,457 0 \5\ 68,739 6.5
Offshore.
Pantropical spotted dolphin............. Western North Atlantic.... 419 1 420 0 \6\ 1,403 30
Atlantic spotted dolphin................ Western North Atlantic.... 1,768 6 1,774 0 \5\ 39,352 4.5
Spinner dolphin......................... Western North Atlantic.... 149 0 149 0 \6\ 885 16.8
Clymene dolphin......................... Western North Atlantic.... 0 0 \2\ 182 0 \6\ 8,576 2.1
Striped dolphin......................... Western North Atlantic.... 0 0 \1\ 46 0 \6\ 54,707 <0.1
Fraser's dolphin........................ Western North Atlantic.... 226 1 227 0 \6\ 658 34.5
Risso's dolphin......................... Western North Atlantic.... 1,277 3 1,280 0 \5\ 24,260 5.3
Common dolphin.......................... Western North Atlantic.... 181 1 182 0 \5\ 144,036 0.1
Melon-headed whale...................... Western North Atlantic.... 212 1 213 0 \6\ 618 34.5
Pygmy killer whale...................... Western North Atlantic.... 20 0 20 0 \6\ 68 29.4
False killer whale...................... Western North Atlantic.... 4 0 \2\ 6 0 \6\ 139 4.3
Killer whale............................ Western North Atlantic.... 6 0 6 0 \6\ 73 8.2
Harbor porpoise......................... Gulf of Maine/Bay of Fundy 0 0 \1\ 3 0 \5\ 55,049 <0.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Take increased to mean group size from AMAPPS (Palka et al., 2017 and 2021).
\2\ Take increased to mean group size from Ocean Biogeographic Information System (OBIS) (2023).
\3\ Modeled abundance (Roberts et al., 2023) used unless noted.
\4\ Abundance from draft 2022 U.S, Atlantic and Gulf of Mexico Marine Mammal SARs.
\5\ Averaged monthly (May-Oct) abundance.
\6\ Only single annual abundance given.
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
[[Page 45182]]
stocks, and their habitat. This considers the nature of the potential
adverse impact being mitigated (likelihood, scope, range). It further
considers the likelihood that the measure will be effective if
implemented (probability of accomplishing the mitigating result if
implemented as planned), the likelihood of effective implementation
(probability implemented as planned), and;
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost, and impact on
operations.
Vessel-Based Visual Mitigation Monitoring
Visual monitoring requires the use of trained observers (herein
referred to as visual protected species observers (PSO)) to scan the
ocean surface for the presence of marine mammals. The area to be
scanned visually includes primarily the shutdown zone (SZ), within
which observation of certain marine mammals requires shutdown of the
acoustic source, but also a buffer zone and, to the extent possible
depending on conditions, the surrounding waters. The buffer zone means
an area beyond the SZ to be monitored for the presence of marine
mammals that may enter the SZ. During pre-start clearance monitoring
(i.e., before ramp-up begins), the buffer zone also acts as an
extension of the SZ in that observations of marine mammals within the
buffer zone would also prevent airgun operations from beginning (i.e.,
ramp-up). The buffer zone encompasses the area at and below the sea
surface from the edge of the 0-500 m SZ, out to a radius of 1,000 m
from the edges of the airgun array (500-1,000 m). This 1,000-m zone (SZ
plus buffer) represents the pre-start clearance zone. Visual monitoring
of the SZ and adjacent waters is intended to establish and, when visual
conditions allow, maintain zones around the sound source that are clear
of marine mammals, thereby reducing or eliminating the potential for
injury and minimizing the potential for more severe behavioral
reactions for animals occurring closer to the vessel. Visual monitoring
of the buffer zone is intended to (1) provide additional protection to
marine mammals that may be in the vicinity of the vessel during pre-
start clearance, and (2) during airgun use, aid in establishing and
maintaining the SZ by alerting the visual observer and crew of marine
mammals that are outside of, but may approach and enter, the SZ.
L-DEO must use dedicated, trained, and NMFS-approved PSOs. The PSOs
must have no tasks other than to conduct observational effort, record
observational data, and communicate with and instruct relevant vessel
crew with regard to the presence of marine mammals and mitigation
requirements. PSO resumes shall be provided to NMFS for approval.
At least one of the visual and two of the acoustic PSOs (discussed
below) aboard the vessel must have a minimum of 90 days at-sea
experience working in those roles, respectively, with no more than 18
months elapsed since the conclusion of the at-sea experience. One
visual PSO with such experience shall be designated as the lead for the
entire protected species observation team. The lead PSO shall serve as
primary point of contact for the vessel operator and ensure all PSO
requirements per the IHA are met. To the maximum extent practicable,
the experienced PSOs should be scheduled to be on duty with those PSOs
with appropriate training but who have not yet gained relevant
experience.
During survey operations (e.g., any day on which use of the airgun
array is planned to occur, and whenever the airgun array is in the
water, whether activated or not), a minimum of two visual PSOs must be
on duty and conducting visual observations at all times during daylight
hours (i.e., from 30 minutes prior to sunrise through 30 minutes
following sunset). Visual monitoring of the pre-start clearance zone
must begin no less than 30 minutes prior to ramp-up, and monitoring
must continue until 1 hour after use of the airgun array ceases or
until 30 minutes past sunset. Visual PSOs shall coordinate to ensure
360[deg] visual coverage around the vessel from the most appropriate
observation posts, and shall conduct visual observations using
binoculars and the naked eye while free from distractions and in a
consistent, systematic, and diligent manner.
PSOs shall establish and monitor the shutdown and buffer zones.
These zones shall be based upon the radial distance from the edges of
the airgun array (rather than being based on the center of the array or
around the vessel itself). During use of the airgun array (i.e.,
anytime airguns are active, including ramp-up), detections of marine
mammals within the buffer zone (but outside the SZ) shall be
communicated to the operator to prepare for the potential shutdown of
the airgun array. Visual PSOs will immediately communicate all
observations to the on duty acoustic PSO(s), including any
determination by the PSO regarding species identification, distance,
and bearing and the degree of confidence in the determination. Any
observations of marine mammals by crew members shall be relayed to the
PSO team. During good conditions (e.g., daylight hours; Beaufort sea
state (BSS) 3 or less), visual PSOs shall conduct observations when the
airgun array is not operating for comparison of sighting rates and
behavior with and without use of the airgun array and between
acquisition periods, to the maximum extent practicable.
Visual PSOs may be on watch for a maximum of 4 consecutive hours
followed by a break of at least 1 hour between watches and may conduct
a maximum of 12 hours of observation per 24-hour period. Combined
observational duties (visual and acoustic but not at same time) may not
exceed 12 hours per 24-hour period for any individual PSO.
Passive Acoustic Monitoring
Passive acoustic monitoring (PAM) means the use of trained
personnel (sometimes referred to as PAM operators, herein referred to
as acoustic PSOs) to operate PAM equipment to acoustically detect the
presence of marine mammals. Acoustic monitoring involves acoustically
detecting marine mammals regardless of distance from the source, as
localization of animals may not always be possible. Acoustic monitoring
is intended to further support visual monitoring (during daylight
hours) in maintaining an SZ around the sound source that is clear of
marine mammals. In cases where visual monitoring is not effective
(e.g., due to weather, nighttime), acoustic monitoring may be used to
allow certain activities to occur, as further detailed below.
PAM would take place in addition to the visual monitoring program.
Visual monitoring typically is not effective during periods of poor
visibility or at night, and even with good visibility, is unable to
detect marine mammals when they are below the surface or beyond visual
range. Acoustic monitoring can be used in addition to visual
observations to improve detection, identification, and localization of
cetaceans. The acoustic monitoring would serve to alert visual PSOs (if
on duty) when vocalizing cetaceans are detected. It is only useful when
marine mammals vocalize, but it can be effective either by day or by
night, and does not depend on good visibility. It would be monitored in
real time so that the visual observers can be advised when cetaceans
are detected.
The R/V Langseth will use a towed PAM system, which must be
monitored by at a minimum one on duty acoustic PSO beginning at least
30 minutes prior to ramp-up and at all times during use
[[Page 45183]]
of the airgun array. Acoustic PSOs may be on watch for a maximum of 4
consecutive hours followed by a break of at least 1 hour between
watches and may conduct a maximum of 12 hours of observation per 24-
hour period. Combined observational duties (acoustic and visual but not
at same time) may not exceed 12 hours per 24-hour period for any
individual PSO.
Survey activity may continue for 30 minutes when the PAM system
malfunctions or is damaged, while the acoustic PSO diagnoses the issue.
If the diagnosis indicates that the PAM system must be repaired to
solve the problem, operations may continue for an additional 10 hours
without acoustic monitoring during daylight hours only under the
following conditions:
<bullet> Sea state is less than or equal to BSS 4;
<bullet> No marine mammals (excluding delphinids) detected solely
by PAM in the applicable SZ in the previous 2 hours;
<bullet> 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
<bullet> Operations with an active airgun array, but without an
operating PAM system, do not exceed a cumulative total of 10 hours in
any 24-hour period.
Establishment of Shutdown and Pre-Start Clearance Zones
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 would establish a minimum SZ with a 500-m radius. The 500-m SZ
would be based on radial distance from the edge of the airgun array
(rather than being based on the center of the array or around the
vessel itself). With certain exceptions (described below), if a marine
mammal appears within or enters this zone, the airgun array would be
shut down.
The pre-start clearance zone is defined as the area that must be
clear of marine mammals prior to beginning ramp-up of the airgun array,
and includes the SZ plus the buffer zone. Detections of marine mammals
within the pre-start clearance zone would prevent airgun operations
from beginning (i.e., ramp-up).
The 500-m SZ is intended to be precautionary in the sense that it
would be expected to contain sound exceeding the injury criteria for
all cetacean hearing groups, (based on the dual criteria of
SEL<INF>cum</INF> and peak SPL), while also providing a consistent,
reasonably observable zone within which PSOs would typically be able to
conduct effective observational effort. Additionally, a 500-m 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, as NMFS
concludes that this extended SZ is sufficiently protective to mitigate
harassment to beaked whales and Kogia species.
Pre-Start Clearance and Ramp-Up
Ramp-up (sometimes referred to as ``soft start'') means the gradual
and systematic increase of emitted sound levels from an airgun array.
Ramp-up begins by first activating a single airgun of the smallest
volume, followed by doubling the number of active elements in stages
until the full complement of an array's airguns are active. Each stage
should be approximately the same duration, and the total duration
should not be less than approximately 20 minutes. The intent of pre-
start clearance observation (30 minutes) is to ensure no marine mammals
are observed within the pre-start clearance zone (or extended SZ, for
beaked whales and Kogia spp.) prior to the beginning of ramp-up. During
the pre-start clearance period is the only time observations of marine
mammals in the buffer zone would prevent operations (i.e., the
beginning of ramp-up). The intent of ramp-up is to warn marine mammals
of pending seismic survey operations and to allow sufficient time for
those animals to leave the immediate vicinity prior to the sound source
reaching full intensity. A ramp-up procedure, involving a step-wise
increase in the number of airguns firing and total array volume until
all operational airguns are activated and the full volume is achieved,
is required at all times as part of the activation of the airgun array.
All operators must adhere to the following pre-start clearance and
ramp-up requirements:
<bullet> 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);
<bullet> Ramp-ups shall be scheduled so as to minimize the time
spent with the source activated prior to reaching the designated run-
in;
<bullet> 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;
<bullet> 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);
<bullet> 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;
<bullet> 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;
<bullet> Ramp-up may occur at times of poor visibility, including
nighttime, if appropriate acoustic monitoring has occurred with no
detections in the 30 minutes prior to beginning ramp-up. Airgun array
activation may only occur at times of poor visibility where operational
planning cannot reasonably avoid such circumstances;
<bullet> If the airgun array is shut down for brief periods (i.e.,
less than 30 minutes) for reasons other than implementation of
prescribed mitigation (e.g., mechanical difficulty), it may be
activated again without ramp-up if PSOs
[[Page 45184]]
have maintained constant visual and/or acoustic observation and no
visual or acoustic detections of marine mammals have occurred within
the pre-start clearance zone (or extended SZ, where applicable). For
any longer shutdown, pre-start clearance observation and ramp-up are
required.; and
<bullet> Testing of the airgun array involving all elements
requires ramp-up. Testing limited to individual source elements or
strings does not require ramp-up but does require pre-start clearance
of 30 minutes.
Shutdown
The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array. Any PSO on
duty will have the authority to delay the start of survey operations or
to call for shutdown of the airgun array if a marine mammal is detected
within the applicable SZ. The operator must also establish and maintain
clear lines of communication directly between PSOs on duty and crew
controlling the airgun array to ensure that shutdown commands are
conveyed swiftly while allowing PSOs to maintain watch. When both
visual and acoustic PSOs are on duty, all detections will be
immediately communicated to the remainder of the on-duty PSO team for
potential verification of visual observations by the acoustic PSO or of
acoustic detections by visual PSOs. When the airgun array is active
(i.e., anytime one or more airguns is active, including during ramp-up)
and (1) a marine mammal appears within or enters the applicable SZ and/
or (2) a marine mammal (other than delphinids, see below) is detected
acoustically and localized within the applicable SZ, the airgun array
will be shut down. When shutdown is called for by a PSO, the airgun
array will be immediately deactivated and any dispute resolved only
following deactivation. Additionally, shutdown will occur whenever PAM
alone (without visual sighting), confirms presence of marine mammal(s)
in the SZ. If the acoustic PSO cannot confirm presence within the SZ,
visual PSOs will be notified but shutdown is not required.
Following a shutdown, airgun activity would not resume until the
marine mammal has cleared the SZ. The animal would be considered to
have cleared the SZ if it is visually observed to have departed the SZ
(i.e., animal is not required to fully exit the buffer zone where
applicable), or it has not been seen within the SZ for 15 minutes for
small odontocetes, or 30 minutes for all mysticetes and all other
odontocetes, including sperm whales, beaked whales, Kogia species, and
large delphinids, such as pilot whales.
The shutdown requirement is waived for small dolphins if an
individual is detected within the SZ. As defined here, the small
dolphin group is intended to encompass those members of the Family
Delphinidae most likely to voluntarily approach the source vessel for
purposes of interacting with the vessel and/or airgun array (e.g., bow
riding). This exception to the shutdown requirement applies solely to
specific genera of small dolphins (Delphinus, Lagenodelphis, Stenella,
Steno, and Tursiops).
We include this small dolphin exception because shutdown
requirements for small dolphins under all circumstances represent
practicability concerns without likely commensurate benefits for the
animals in question. Small dolphins are generally the most commonly
observed marine mammals in the specific geographic region and would
typically be the only marine mammals likely to intentionally approach
the vessel. As described above, auditory injury is extremely unlikely
to occur for MF cetaceans (e.g., delphinids), as this group is
relatively insensitive to sound produced at the predominant frequencies
in an airgun pulse while also having a relatively high threshold for
the onset of auditory injury (i.e., permanent threshold shift).
A large body of anecdotal evidence indicates that small dolphins
commonly approach vessels and/or towed arrays during active sound
production for purposes of bow riding, with no apparent effect observed
(e.g., Barkaszi et al., 2012; Barkaszi and Kelly, 2018). The potential
for increased shutdowns resulting from such a measure would require the
Langseth to revisit the missed track line to reacquire data, resulting
in an overall increase in the total sound energy input to the marine
environment and an increase in the total duration over which the survey
is active in a given area. Although other MF hearing specialists (e.g.,
large delphinids) are no more likely to incur auditory injury than are
small dolphins, they are much less likely to approach vessels.
Therefore, retaining a shutdown requirement for large delphinids would
not have similar impacts in terms of either practicability for the
applicant or corollary increase in sound energy output and time on the
water. We do anticipate some benefit for a shutdown requirement for
large delphinids in that it simplifies somewhat the total range of
decision-making for PSOs and may preclude any potential for
physiological effects other than to the auditory system as well as some
more severe behavioral reactions for any such animals in close
proximity to the Langseth.
Visual PSOs shall use best professional judgment in making the
decision to call for a shutdown if there is uncertainty regarding
identification (i.e., whether the observed marine mammal(s) belongs to
one of the delphinid genera for which shutdown is waived or one of the
species with a larger SZ).
L-DEO must implement shutdown if a marine mammal species for which
take was not authorized, or a species for which authorization was
granted but the authorized takes have been met, approaches the Level A
or Level B harassment zones. L-DEO must also implement 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 personnel should use an appropriate reference guide that
includes identifying information on all marine mammals that may be
encountered. Vessel operators must comply with the below measures
except under extraordinary circumstances when the safety of the vessel
or crew is in doubt or the safety of life at sea is in question. These
requirements do not apply in any case where compliance would create an
imminent and serious threat to a person or vessel or to the extent that
a vessel is restricted in its ability to maneuver and, because of the
restriction, cannot comply.
Vessel operators and crews must maintain a vigilant watch for all
marine mammals and slow down, stop their vessel, or alter course, as
appropriate and regardless of vessel size, to avoid striking any marine
mammal. A single marine mammal at the surface may indicate the presence
of submerged animals in the vicinity of the vessel; therefore,
precautionary measures should always be exercised. A visual observer
aboard the vessel must monitor a vessel strike avoidance zone around
the vessel (distances stated below). Visual observers monitoring the
vessel strike avoidance zone may be third-party observers (i.e., PSOs)
or crew members, but crew members responsible for these duties must be
provided sufficient training to (1)
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distinguish marine mammals from other phenomena and (2) broadly to
identify a marine mammal as a right whale, other whale (defined in this
context as sperm whales or baleen whales other than right whales), or
other marine mammals.
All vessels, regardless of size, must observe a 10-knot 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) (when in effect) and any dynamic
management areas (DMA) (when in effect). See <a href="http://www.fisheries.noaa.gov/national/endangered-species-conservation/reducing-ship-strikes-north-atlantic-right-whales">www.fisheries.noaa.gov/national/endangered-species-conservation/reducing-ship-strikes-north-atlantic-right-whales</a> for specific detail regarding these areas.
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 right whales. If a right whale is sighted within the relevant
separation distance, the vessel must steer a course away at 10 knots or
less until the 500-m separation distance has been established. If a
whale is observed but cannot be confirmed as a species other than a
right whale, the vessel operator must assume that it is a right whale
and take appropriate action.
All vessels must maintain a minimum separation distance of 100 m
from sperm whales and all other baleen whales.
All vessels must, to the maximum extent practicable, attempt to
maintain a minimum separation distance of 50 m from all other marine
mammals, with an understanding that at times this may not be possible
(e.g., for animals that approach the vessel).
When marine mammals are sighted while a vessel is underway, the
vessel shall take action as necessary to avoid violating the relevant
separation distance (e.g., attempt to remain parallel to the animal's
course, avoid excessive speed or abrupt changes in direction until the
animal has left the area). If marine mammals are sighted within the
relevant separation distance, the vessel must reduce speed and shift
the engine to neutral, not engaging the engines until animals are clear
of the area. This does not apply to any vessel towing gear or any
vessel that is navigationally constrained.
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, L-DEO must submit daily
observations to the NMFS 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 at <a href="/cdn-cgi/l/email-protection#81efece7f2aff2e4f3aff3e4f2e4e0f3e2e9afefeef5e8e7e8e2e0f5e8eeefc1efeee0e0afe6eef7"><span class="__cf_email__" data-cfemail="3b55565d4815485e4915495e485e5a4958531555544f525d52585a4f5254557b55545a5a155c544d">[email protected]</span></a>.
To further prevent exposure of North Atlantic right whales during a
time when they may start to migrate to calving and nursing grounds in
coastal and shelf waters adjacent to the survey area, the L-DEO must
not conduct seismic survey activities in the nearshore portions (i.e.,
survey tracklines) of the action area on or after October 1 through
April 30. We define ``nearshore lines'' as those within 100 km of the
U.S. shore in areas north of 31[deg] N and within 80 km from the U.S.
shore in areas south of 31[deg] N. Relative to the survey area, these
nearshore portions of the survey area overlap with higher density areas
for North Atlantic right whale during the month of October as shown in
Roberts et al. (2023).
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:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
<bullet> Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through 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);
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
<bullet> How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and
<bullet> Mitigation and monitoring effectiveness.
Vessel-Based Visual Monitoring
As described above, PSO observations would take place during
daytime airgun operations. During seismic survey operations, at least
five visual PSOs would be based aboard the Langseth. Two visual PSOs
would be on duty at all times during daytime hours. Monitoring shall be
conducted in accordance with the following requirements:
<bullet> The operator shall provide PSOs with bigeye binoculars
(e.g., 25 x 150; 2.7 view angle; individual ocular focus; height
control) of appropriate quality solely for PSO use. These shall be
pedestal-mounted on the deck at the most appropriate vantage point that
provides for optimal sea surface observation, PSO safety, and safe
operation of the vessel; and
<bullet> 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:
<bullet> PSOs shall be independent, dedicated, trained visual and
acoustic PSOs and must be employed by a third-party observer provider;
[[Page 45186]]
<bullet> 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);
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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
<bullet> 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.
<bullet> For data collection purposes, PSOs shall use standardized
electronic data collection forms. PSOs shall record detailed
information about any implementation of mitigation requirements,
including the distance of animals to the airgun array and description
of specific actions that ensued, the behavior of the animal(s), any
observed changes in behavior before and after implementation of
mitigation, and if shutdown was implemented, the length of time before
any subsequent ramp-up of the airgun array. If required mitigation was
not implemented, PSOs should record a description of the circumstances.
At a minimum, the following information must be recorded:
<bullet> Vessel name, vessel size and type, maximum speed
capability of vessel;
<bullet> Dates (MM/DD/YYYY) of departures and returns to port with
port name;
<bullet> PSO names and affiliations, PSO ID (initials or other
identifier);
<bullet> Date (MM/DD/YYYY) and participants of PSO briefings;
<bullet> Visual monitoring equipment used (description);
<bullet> PSO location on vessel and height (meters) of observation
location above water surface;
<bullet> Watch status (description);
<bullet> Dates (MM/DD/YYYY) and times (Greenwich Mean Time/UTC) of
survey on/off effort and times (GMC/UTC) corresponding with PSO on/off
effort;
<bullet> Vessel location (decimal degrees) when survey effort began
and ended and vessel location at beginning and end of visual PSO duty
shifts;
<bullet> Vessel location (decimal degrees) at 30-second intervals
if obtainable from data collection software, otherwise at practical
regular interval;
<bullet> Vessel heading (compass heading) and speed (knots) at
beginning and end of visual PSO duty shifts and upon any change;
<bullet> Water depth (meters) (if obtainable from data collection
software);
<bullet> Environmental conditions while on visual survey (at
beginning and end of PSO shift and whenever conditions changed
significantly), including BSS and any other relevant weather conditions
including cloud cover, fog, sun glare, and overall visibility to the
horizon;
<bullet> Factors that may have contributed to impaired observations
during each PSO shift change or as needed as environmental conditions
changed (description) (e.g., vessel traffic, equipment malfunctions);
and
<bullet> Vessel/Survey activity information (and changes thereof)
(description), such as airgun power output while in operation, number
and volume of airguns operating in the array, tow depth of the array,
and any other notes of significance (i.e., pre-start clearance, ramp-
up, shutdown, testing, shooting, ramp-up completion, end of operations,
streamers, etc.).
<bullet> Upon visual observation of any marine mammals, the
following information must be recorded:
<bullet> Sighting ID (numeric);
<bullet> Watch status (sighting made by PSO on/off effort,
opportunistic, crew, alternate vessel/platform);
<bullet> Location of PSO/observer (description);
<bullet> Vessel activity at the time of the sighting (e.g.,
deploying, recovering, testing, shooting, data acquisition, other);
<bullet> PSO who sighted the animal/ID;
<bullet> Time/date of sighting (GMT/UTC, MM/DD/YYYY);
<bullet> Initial detection method (description);
<bullet> Sighting cue (description);
<bullet> Vessel location at time of sighting (decimal degrees);
<bullet> Water depth (meters);
<bullet> Direction of vessel's travel (compass direction);
<bullet> Speed (knots) of the vessel from which the observation was
made;
<bullet> Direction of animal's travel relative to the vessel
(description, compass heading);
<bullet> Bearing to sighting (degrees);
<bullet> Identification of the animal (e.g., genus/species, lowest
possible taxonomic level, or unidentified) and the composition of the
group if there is a mix of species;
<bullet> Species reliability (an indicator of confidence in
identification) (1 = unsure/possible, 2 = probable, 3 = definite/sure,
9 = unknown/not recorded);
<bullet> Estimated distance to the animal (meters) and method of
estimating distance;
<bullet> Estimated number of animals (high/low/best) (numeric);
<bullet> Estimated number of animals by cohort (adults, yearlings,
juveniles, calves, group composition, etc.);
<bullet> Description (as many distinguishing features as possible
of each individual seen, including length, shape, color, pattern, scars
or markings, shape and size of dorsal fin, shape of head, and blow
characteristics);
<bullet> Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding,
traveling; as explicit and detailed as possible; note any observed
changes in behavior);
<bullet> Animal's closest point of approach (meters) and/or closest
distance from any element of the airgun array;
<bullet> Description of any actions implemented in response to the
sighting
[[Page 45187]]
(e.g., delays, shutdown, ramp-up) and time and location of the action.
<bullet> Photos (Yes/No);
<bullet> Photo Frame Numbers (List of numbers); and
<bullet> Conditions at time of sighting (Visibility; Beaufort Sea
State);
If a marine mammal is detected while using the PAM system, the
following information should be recorded:
<bullet> An acoustic encounter identification number, and whether
the detection was linked with a visual sighting;
<bullet> Date and time when first and last heard;
<bullet> Types and nature of sounds heard (e.g., clicks, whistles,
creaks, burst pulses, continuous, sporadic, strength of signal); and
<bullet> Any additional information recorded such as water depth of
the hydrophone array, bearing of the animal to the vessel (if
determinable), species or taxonomic group (if determinable),
spectrogram screenshot, and any other notable information.
Reporting
The Holder shall submit a draft comprehensive report on all
activities and monitoring results within 90 days of the completion of
the survey or expiration of the IHA, whichever comes sooner. The report
must describe all activities conducted and sightings of marine mammals,
must provide full documentation of methods, results, and interpretation
pertaining to all monitoring, and must summarize the dates and
locations of survey operations and all marine mammal sightings (dates,
times, locations, activities, associated survey activities). The draft
report shall also include geo-referenced time-stamped vessel tracklines
for all time periods during which airgun arrays were operating.
Tracklines should include points recording any change in airgun array
status (e.g., when the sources began operating, when they were turned
off, or when they changed operational status such as from full array to
single gun or vice versa). GIS files shall be provided in 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. The
report must summarize data collected as described above in ``Data
Collection.'' A final report must be submitted within 30 days following
resolution of any comments on the draft report.
The report must include a validation document concerning the use of
PAM, which should include necessary noise validation diagrams and
demonstrate whether background noise levels on the PAM deployment
limited achievement of the planned detection goals. Copies of any
vessel self-noise assessment reports must be included with the report.
Reporting NARW
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 the survey activities discover an injured or dead
marine mammal, the L-DEO shall report the incident to the OPR, NMFS,
and to the NMFS Southeast Regional Stranding Coordinator as soon as
feasible. The report must include the following information:
<bullet> Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Condition of the animal(s) (including carcass condition if
the animal is dead);
<bullet> Observed behaviors of the animal(s), if alive;
<bullet> If available, photographs or video footage of the
animal(s); and
<bullet> General circumstances under which the animal was
discovered.
Vessel strike--In the event of a strike of a marine mammal by any
vessel involved in the activities covered by the authorization, L-DEO
shall report the incident to OPR, NMFS, and to the NMFS Southeast
Regional Stranding Coordinator as soon as feasible. The report must
include the following information:
<bullet> Time, date, and location (latitude/longitude) of the
incident;
<bullet> Vessel's speed during and leading up to the incident;
<bullet> Vessel's course/heading and what operations were being
conducted (if applicable);
<bullet> Status of all sound sources in use;
<bullet> Description of avoidance measures/requirements that were
in place at the time of the strike and what additional measure were
taken, if any, to avoid strike;
<bullet> Environmental conditions (e.g., wind speed and direction,
BSS, cloud cover, visibility) immediately preceding the strike;
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Estimated size and length of the animal that was struck;
<bullet> Description of the behavior of the marine mammal
immediately preceding and following the strike;
<bullet> If available, description of the presence and behavior of
any other marine mammals present immediately preceding the strike;
<bullet> Estimated fate of the animal (e.g., dead, injured but
alive, injured and moving, blood or tissue observed in the water,
status unknown, disappeared); and
<bullet> To the extent practicable, photographs or video footage of
the animal(s).
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 airgun
arrays operating within 50 km of the stranding. Shutdown procedures for
live stranding or milling marine mammals include the following: if at
any time, the marine mammal(s) die or are euthanized, or if herding/
intervention efforts are stopped, the Director of OPR, NMFS (or
designee), will advise the IHA-holder that the shutdown around the
animals' location is no longer needed. Otherwise, shutdown procedures
will remain in effect until the Director of OPR, NMFS (or designee),
determines and advises L-DEO that all live animals involved have left
the area (either of their own volition or following an intervention).
If further observations of the marine mammals indicate the
potential for re-stranding, additional coordination with the IHA-holder
will be required to determine what measures are necessary to minimize
that likelihood (e.g., extending the shutdown or moving operations
farther away) and to implement those measures as appropriate.
Additional Information Requests--if NMFS determines that the
circumstances of any marine mammal
[[Page 45188]]
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:
<bullet> 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
<bullet> If available, description of the behavior of any marine
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and
immediately after the discovery of the stranding.
In the event that the investigation is still inconclusive, the
investigation of the association of the survey activities is still
warranted, and the investigation is still being pursued, NMFS may
provide additional information requests, in writing, regarding the
nature and location of survey operations prior to the time period
above.
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), as well as
effects on habitat, and the likely effectiveness of the mitigation. We
also assess the number, intensity, and context of estimated takes by
evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338,
September 29, 1989), the impacts from other past and ongoing
anthropogenic activities are incorporated into this analysis via their
impacts on the baseline (e.g., as reflected in the regulatory status of
the species, population size and growth rate where known, ongoing
sources of human-caused mortality, or ambient noise levels).
To avoid repetition, the discussion of our analysis applies to all
the species listed in Table 1, given that the anticipated effects of
this activity on these different marine mammal stocks are expected to
be similar. Where there are meaningful differences between species or
stocks they are included as separate subsections below. NMFS does not
anticipate that serious injury or mortality would occur as a result of
L-DEO's planned survey, even in the absence of mitigation, and no
serious injury or mortality is authorized. As discussed in the
``Potential Effects of Specified Activities on Marine Mammals and Their
Habitat'' section above, non-auditory physical effects and vessel
strike are not expected to occur. NMFS expects that the majority of
potential takes would be in the form of short-term Level B behavioral
harassment 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).
We are authorizing a limited number of Level A harassment of 4
species in the form of PTS, and Level B harassment only of the
remaining marine mammal species. If any PTS is incurred in marine
mammals as a result of the planned activity, we expect only a small
degree of PTS that would not result in severe hearing impairment
because of the constant movement of both the Langseth and of the marine
mammals in the project areas, as well as the fact that the vessel is
not expected to remain in any one area in which individual marine
mammals would be expected to concentrate for an extended period of
time. Additionally, L-DEO would shut down the airgun array if marine
mammals approach within 500 m (with the exception of specific genera of
dolphins, see ``Mitigation'' section), 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 would be unlikely to affect the fitness of
any individuals. Also, as described above, we expect that marine
mammals would likely move away from a sound source that represents an
aversive stimulus, especially at levels that would be expected to
result in PTS, given sufficient notice of the Langseth's approach due
to the vessel's relatively low speed when conducting seismic surveys.
Accordingly, we expect that the majority of takes would be in the form
of short-term Level B behavioral harassment in the form of temporary
avoidance of the area or decreased foraging (if such activity were
occurring), reactions that are considered to be of low severity and
with no lasting biological consequences (e.g., Southall et al., 2007;
Ellison et al., 2012).
In addition to being temporary, the maximum expected Level B
harassment zone around the survey vessel is 6,733 m for water depths
greater than 1,000 m (and up to 10,100 m in water depths of 100 to
1,000 m). Therefore, the ensonified area surrounding the vessel is
relatively small compared to the overall distribution of animals in the
area and their use of the habitat. Feeding behavior is not likely to be
significantly impacted as prey species are mobile and are broadly
distributed throughout the survey area; therefore, marine mammals that
may be temporarily displaced during survey activities are expected to
be able to resume foraging once they have moved away from areas with
disturbing levels of underwater noise. Because of the short duration
(40 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)
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
[[Page 45189]]
DPS) remains stable at approximately 12,000 individuals.
Beginning in January 2017, elevated minke whale strandings have
occurred along the Atlantic coast from Maine through South Carolina,
with highest numbers in Massachusetts, Maine, and New York. This event
does not provide cause for concern regarding population level impacts,
as the likely population abundance is greater than 20,000 whales, and
the UME is pending closure.
The mitigation measures are expected to reduce the number and/or
severity of takes for all species listed in Table 1, including those
with active UMEs, to the level of least practicable adverse impact. In
particular they would provide animals the opportunity to move away from
the sound source throughout the survey area before seismic survey
equipment reaches full energy, thus preventing them from being exposed
to sound levels that have the potential to cause injury (Level A
harassment) or more severe Level B harassment.
In summary and as described above, the following factors primarily
support our determination that the impacts resulting from this activity
are not expected to adversely affect any of the species or stocks
through effects on annual rates of recruitment or survival:
<bullet> No serious injury or mortality is anticipated or
authorized;
<bullet> The activity is temporary and of relatively short duration
(40 days);
<bullet> The vast majority of anticipated impacts of the activity
on marine mammals would be temporary behavioral changes due to
avoidance of the area around the vessel;
<bullet> 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;
<bullet> The potential adverse effects on fish or invertebrate
species that serve as prey species for marine mammals from the survey
would be temporary and spatially limited, and impacts to marine mammal
foraging would be minimal;
<bullet> 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
<bullet> The mitigation measures, including visual and acoustic
shutdowns are expected to minimize potential impacts to marine mammals
(both amount and severity).
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the monitoring and mitigation
measures, NMFS finds that the total marine mammal take from the
activity will have a negligible impact on all affected marine mammal
species or stocks.
Small Numbers
As noted previously, only take of small numbers of marine mammals
may be authorized under sections 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. When the predicted number of
individuals to be taken is fewer than one-third of the species or stock
abundance, the take is considered to be of small numbers. Additionally,
other qualitative factors may be considered in the analysis, such as
the temporal or spatial scale of the activities.
The amount of take NMFS is authorizing is below one-third of the
estimated stock abundance for all species with available abundance
estimates except for melon headed whale and Fraser's dolphin; for these
species, the amount of take authorized by NMFS could amount to 34.5
percent of the modeled population abundance. Applying qualitative
factors into our analysis, however, NMFS anticipates that actual take
will be well below the one-third threshold. First, spatial factors lead
us to believe only small numbers of the species will be taken given
that the survey area is a very small fraction of these species' range.
The melon headed whale occurs in deep waters offshore of the
southeastern U.S. and in the Gulf of Mexico extending as far south as
southern Brazil, while Fraser's dolphin also occurs off the Western
Atlantic in deep waters (1,000 m) from the Gulf of Mexico extending as
far south as Uruguay. The Blake Plateau is a tiny fraction of these
wide ranges, and NMFS does not anticipate, based on the species'
behavior and life histories, a substantial percentage of either stock
to concentrate in the Blake Plateau. This prediction is additionally
informed by the fact that there have been zero OBIS database sightings
of either species within the survey area. Second, temporal factors
suggest only small numbers of take given that the activity would occur
only over 40 days and during this brief period it is extremely unlikely
that significant numbers of individual members of these species will be
present near the survey area. Last, our calculation of 34.5 percent
take is conservative in that it assumes that each anticipated take
affects a different individual from the population. In fact, certain
individuals may experience more than a single take, and given that
fact, we would expect actual take to affect well below one-third of the
relevant populations.
Based on the analysis contained herein of the planned activity
(including the mitigation and monitoring measures) and the anticipated
take of marine mammals, NMFS finds that small numbers of marine mammals
would be taken relative to the population size of the affected species
or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.
Endangered Species Act
Section 7(a)(2) of the 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 authorize take for endangered or
threatened species, in this case with the ESA Interagency Cooperation
Division within NMFS' OPR.
The NMFS OPR ESA Interagency Cooperation Division issued a
Biological Opinion under section 7 of the ESA, on the issuance of an
IHA to L-DEO under section 101(a)(5)(D) of the MMPA by the NMFS OPR
Permits and Conservation Division. The Biological Opinion concluded
that the action is not likely to jeopardize the continued existence of
ESA-listed North Atlantic right whales, blue whales, fin whales, sei
whales, and sperm whales.
[[Page 45190]]
National Environmental Policy Act (NEPA)
In compliance with the National Environmental Policy Act of 1969
(42 U.S.C. 4321 et seq.), as implemented by the regulations published
by the Council on Environmental Quality (40 CFR parts 1500-1508), the
NSF prepared an Environmental Analysis (EA) to consider the direct,
indirect, and cumulative effects to the human environment from the
planned marine geophysical survey off of 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 Council on Environmental Quality regulations, as well as
NOAA Administrative Order 216-6, NMFS has reviewed the NSF's EA,
determined it to be sufficient, and adopted that EA and signed a
Finding of No Significant Impact (FONSI) available on our website at
<a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-lamont-doherty-earth-observatorys-marine-geophysical-surveys">https://www.fisheries.noaa.gov/action/incidental-take-authorization-lamont-doherty-earth-observatorys-marine-geophysical-surveys</a>. NSF's EA
is available at <a href="https://www.nsf.gov/geo/oce/envcomp/">https://www.nsf.gov/geo/oce/envcomp/</a>.
Authorization
NMFS has issued an IHA to L-DEO for the incidentalharassment of
small numbers of 29 marine mammal species incidental to a marine
geophysical survey of Blake Plateau in the northwest Atlantic Ocean
that includes the previously explained mitigation, monitoring and
reporting requirements.
Dated: July 10, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2023-14946 Filed 7-13-23; 8:45 am]
BILLING CODE 3510-22-P
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