Notice2024-22724
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey of the Chain Transform Fault in the Equatorial 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
October 2, 2024
Effective
September 27, 2024
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 the Lamont-Doherty Earth Observatory of Columbia University (L-DEO) to incidentally harass marine mammals during survey activities associated with a marine geophysical survey at the Chain Transform Fault in the equatorial Atlantic Ocean.
Full Text
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<title>Federal Register, Volume 89 Issue 191 (Wednesday, October 2, 2024)</title>
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[Federal Register Volume 89, Number 191 (Wednesday, October 2, 2024)]
[Notices]
[Pages 80214-80227]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-22724]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XE190]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to a Marine Geophysical Survey of the
Chain Transform Fault in the Equatorial 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
the Lamont-Doherty Earth Observatory of Columbia University (L-DEO) to
incidentally harass marine mammals during survey activities associated
with a marine geophysical survey at the Chain Transform Fault in the
equatorial Atlantic Ocean.
DATES: The authorization is effective from September 27, 2024 through
September 26, 2025.
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/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities</a>. In case of problems accessing these documents, please
call the contact listed below.
FOR FURTHER INFORMATION CONTACT: Jenna Harlacher, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and either regulations
are proposed or, if the taking is limited to harassment, a notice of a
proposed IHA is provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking and other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
[[Page 80215]]
taking for certain subsistence uses (referred to in shorthand as
``mitigation''); and requirements pertaining to the monitoring and
reporting of the takings. The definitions of all applicable MMPA
statutory terms cited above are included in the relevant sections
below.
Summary of Request
On April 15, 2024, NMFS received a request from L-DEO for an IHA to
take marine mammals incidental to conducting a marine geophysical
survey of the Chain Transform Fault in the equatorial Atlantic Ocean.
Following NMFS review of the application and additional clarifying
information from L-DEO, NMFS deemed the application adequate and
complete on May 22, 2024. L-DEO's request is for take of 28 marine
mammal species by Level B harassment, and for take of a subset of 5 of
these species, by Level A harassment. Neither L-DEO nor NMFS expect
serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate. There are no changes from the
proposed IHA to the final IHA.
Description of Activity
Researchers from the Woods Hole Oceanographic Institution,
University of Delaware, University of New Hampshire, Boise State
University and Boston College, with funding from the National Science
Foundation, plan to conduct a high-energy seismic survey using airguns
as the acoustic source from the research vessel (R/V) Marcus G.
Langseth (Langseth), which is owned and operated by L-DEO. The survey
would occur at the Chain Transform Fault, off the coast of Africa, in
the equatorial Atlantic Ocean during austral summer 2024 in the
Southern Hemisphere (i.e., between October 2024 and February 2025). The
survey would occur within International Waters more than 600 kilometers
(km) in the Gulf of Guinea, Africa, in water depths ranging from
approximately 2,000 to 5,500 meters (m). To complete this survey, the
R/V Langseth would tow a 36-airgun array with a total discharge volume
of approximately (~) 6,600 cubic inches (in\3\) at a depth of 9 to 12
m. The airgun array receiving system would consist of a 15 km long
solid-state hydrophone streamer and 20 Ocean Bottom Seismometers (OBS).
The airguns would fire at a shot interval of 37.5 m (~18 seconds (s))
during seismic acquisition. Approximately 2,058 km of total survey
trackline are planned. Airgun arrays would introduce underwater sounds
that may result in take, by Level A and Level B harassment, of marine
mammals.
A detailed description of the planned geophysical survey was
provided in the Federal Register notice of the proposed IHA (89 FR
56158, July 8, 2024). 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 July 8, 2024 (89 FR 56158). That notice
described, in detail, L-DEO's activity, the marine mammal species that
may be affected by the activity, and the anticipated effects on marine
mammals. In that notice, we requested public input on the request for
authorization described therein, our analyses, the proposed
authorization, and any other aspect of the notice of proposed IHA, and
requested that interested persons submit relevant information,
suggestions, and comments. The proposed notice was available for a 30-
day public comment period. NMFS received no public comments.
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the application summarize available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history of the potentially affected species. NMFS
fully considered all of this information, and we refer the reader to
these descriptions, instead of reprinting the information. Additional
information regarding population trends and threats may be found in
NMFS' Stock Assessment Reports (SARs; <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://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
aforementioned source for general information regarding the species
listed in table 1.
The populations of marine mammals found in the survey area do not
occur within the U.S. exclusive economic zone (EEZ) and therefore, are
not assessed in NMFS' SARs. For most species, there are no stocks
defined for management purposes in the survey area, and NMFS is
evaluating impacts at the species level. As such, information on
potential biological removal level (PBR; defined by the MMPA as the
maximum number of animals, not including natural mortalities, that may
be removed from a marine mammal stock while allowing that stock to
reach or maintain its optimum sustainable population) and annual levels
of serious injury and mortality from anthropogenic sources are not
available for these marine mammal populations. Abundance estimates for
marine mammals in the survey location are lacking; therefore, the
modeled abundances presented here are based on a variety of proxy
sources, including the U.S Navy Atlantic Fleet Training and Testing
Area Marine Mammal Density (AFTT) model (Roberts et al., 2023) and the
International Whaling Commission (IWC) Population (Abundance) Estimates
(IWC 2024). The modeled abundance is considered the best scientific
information available on the abundance of marine mammal populations in
the area.
Table 1 lists all species that occur in the survey area that may be
taken as a result of the planned survey and summarizes information
related to the population, including regulatory status under the MMPA
and Endangered Species Act (ESA).
Table 1--Species Likely Impacted by the Specified Activities
----------------------------------------------------------------------------------------------------------------
ESA/MMPA
status; Modeled abundance
Common name Scientific name Stock strategic (Y/ \2\
N) \1\
----------------------------------------------------------------------------------------------------------------
Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
Family Balaenopteridae
(rorquals):
Blue Whale................... Balaenoptera NA.................. E, D, Y \2\ 191/2,\4\ 300
musculus.
[[Page 80216]]
Fin Whale.................... Balaenoptera NA.................. E, D, Y 11,672
physalus.
Humpback Whale............... Megaptera NA.................. -, -, N \2\ 4,990/\5\
novaeangliae. 42,000
Common Minke Whale........... Balaenoptera NA.................. -, -, N 13,784
acutorostrata.
Antarctic Minke Whale........ Balaenoptera NA.................. -, -, N \3\ 515,000
bonaerensis.
Sei Whale.................... Balaenoptera NA.................. E, D, Y 19,530
borealis.
Bryde's Whale................ Balaenoptera edeni. NA.................. -, -, N 536
----------------------------------------------------------------------------------------------------------------
Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
Family Physeteridae:
Sperm Whale.................. Physeter NA.................. E, D, Y 64,015
macrocephalus.
Family Kogiidae:
Pygmy Sperm Whale............ Kogia breviceps.... NA.................. -, -, N \7\ 26,043
Dwarf Sperm Whale............ Kogia sima......... NA.................. -, -, N
Family Ziphiidae (beaked whales):
Blainville's Beaked Whale.... Mesoplodon NA.................. -, -, N \8\ 65,069
densirostris.
Cuvier's Beaked Whale........ Ziphius cavirostris NA.................. -, -, N
Gervais' Beaked Whale........ Mesoplodon NA.................. -, -, N
europaeus.
Family Delphinidae:
Killer Whale................. Orcinus orca....... NA.................. -, -, N 972
Short-Finned Pilot Whale..... Globicephala melas. NA.................. -, -, N \6\ 264,907
Rough-toothed Dolphin........ Steno bredanensis.. NA.................. -, -, N 32,848
Bottlenose Dolphin........... Tursiops truncatus. NA.................. -, -, N 418,151
Risso's Dolphin.............. Grampus griseus.... NA.................. -, -, N 78,205
Common Dolphin............... Delphinus delphis.. NA.................. -, -, N 473,260
Striped Dolphin.............. Stenella NA.................. -, -, N 412,729
coeruleoalba.
Pantropical Spotted Dolphin.. Stenella attenuata. NA.................. -, -, N 321,740
Atlantic Spotted Dolphin..... Stenella frontalis. NA.................. -, -, N 259,519
Spinner Dolphin.............. Stenella NA.................. -, -, N 152,511
longirostris.
Clymene Dolphin.............. Stenella clymene... NA.................. -, -, N 181,209
Fraser's Dolphin............. Lagenodelphis hosei NA.................. -, -, N 19,585
Melon-headed Whale........... Peponocephala NA.................. -, -, N 64,114
electra.
Pygmy Killer Whale........... Feresa attenuata... NA.................. -, -, N 9,001
False Killer Whale........... Pseudorca NA.................. -, -, N 12,682
crassidens.
----------------------------------------------------------------------------------------------------------------
\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\ Modeled abundance value from U.S Navy Atlantic Fleet Training and Testing Area Marine Mammal Density (AFTT)
(Roberts et al., 2023) unless otherwise noted.
\3\ Abundance of minke whales (species unspecified) for the Southern Hemisphere (IWC 2024)
\4\ Abundance of blue whales (excluding pygmy blue whales) for Southern Hemisphere (IWC 2024)
\5\ Abundance of humpback whales on Antarctic feeding grounds (IWC 2024)
\6\ Pilot whale guild.
\7\ Estimate includes dwarf and pygmy sperm whales.
\8\ Beaked whale guild.
All 28 species in table 1 temporally and spatially co-occur with
the activity to the degree that take is reasonably likely to occur. All
species that could potentially occur in the planned survey area are
listed in section 3 of the application.
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 (89 FR 56158, July 8, 2024). 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.). Subsequently, NMFS (2018) described
generalized hearing ranges for these marine mammal hearing groups.
Generalized hearing ranges were chosen based on the approximately 65
decibel (dB) threshold from the normalized composite audiograms, with
the exception for lower limits for low-
[[Page 80217]]
frequency cetaceans where the lower bound was deemed to be biologically
implausible and the lower bound from Southall et al. (2007) retained.
Marine mammal hearing groups and their associated hearing ranges are
provided in table 2.
Table 2--Marine Mammal Hearing Groups
[NMFS, 2018]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
High-frequency (HF) cetaceans (true 275 Hz to 160 kHz.
porpoises, Kogia, river dolphins,
Cephalorhynchid, Lagenorhynchus
cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) 50 Hz to 86 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 39 kHz.
(sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on ~65 dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al. 2007) and PW pinniped (approximation).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
The effects of underwater noise from L-DEO's survey activities have
the potential to result in behavioral harassment of marine mammals in
the vicinity of the survey area. The notice of proposed IHA (89 FR
56158, July 8, 2024) 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 incorporated by reference into this final
IHA determination and is not repeated here; please refer to the notice
of proposed IHA (89 FR 56158, July 8, 2024).
Estimated Take of Marine Mammals
This section provides an estimate of the number of incidental takes
authorized through the IHA, which will inform 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 by Level B harassment, as the
noise from use of the airgun array has the potential to result in
disruption of behavioral patterns for individual marine mammals. There
is also some potential for auditory injury (Level A harassment) to
result for species of certain hearing groups (LF and HF) due to the
size of the predicted auditory injury zones for those groups. Auditory
injury is less likely to occur for mid-frequency species due to their
relative lack of sensitivity to the frequencies at which the primary
energy of an airgun signal is found as well as such species' general
lower sensitivity to auditory injury as compared to high-frequency
cetaceans. As discussed in further detail below, we do not expect
auditory injury for mid-frequency cetaceans. No mortality or serious
injury is anticipated as a result of these activities. Below we
describe how the authorized take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic thresholds above which NMFS believes the best
available science indicates marine mammals will be behaviorally
harassed or incur some degree of permanent hearing impairment; (2) the
area or volume of water that will be ensonified above these levels in a
day; (3) the density or occurrence of marine mammals within these
ensonified areas; and, (4) the number of days of activities. We note
that while these factors can contribute to a basic calculation to
provide an initial prediction of potential takes, additional
information that can qualitatively inform take estimates is also
sometimes available (e.g., previous monitoring results or average group
size). Below, we describe the factors considered here in more detail
and present the take estimates.
Acoustic Thresholds
NMFS recommends the use of acoustic thresholds that identify the
received level of underwater sound above which exposed marine mammals
would be reasonably expected to be behaviorally harassed (equated to
Level B harassment) or to incur permanent threshold shift (PTS) of some
degree (equated to Level A harassment). Acoustic thresholds used in
this analysis were discussed in detail in the notice of proposed IHA
(89 FR 56158, July 8, 2024) and not repeated here. Please see that
notice for additional detail.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that are used in estimating the area ensonified above the
acoustic thresholds, including source levels and transmission loss
coefficient.
When the Technical Guidance was published (NMFS, 2016), in
recognition of the fact that ensonified area/volume could be more
technically challenging to predict because of the duration component in
the new thresholds, we developed a user spreadsheet that includes tools
to help predict a simple isopleth that can be used in conjunction with
marine mammal density or 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
[[Page 80218]]
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 9 m to 12 m. L-
DEO's model results are used to determine the 160 dB root mean square
(rms) radius for the airgun source down to a maximum depth of 2,000 m.
Received sound levels have been predicted by L-DEO's model (Diebold et
al. 2010) as a function of distance from the 36-airgun array. This
modeling approach uses ray tracing for the direct wave traveling from
the array to the receiver and its associated source ghost (reflection
at the air-water interface in the vicinity of the array), in a
constant-velocity half-space (infinite homogeneous ocean layer,
unbounded by a seafloor). In addition, propagation measurements of
pulses from the 36-airgun array at a tow depth of 6 m have been
reported in deep water (~1,600 m), intermediate water depth on the
slope (~600-1,100 m), and shallow water (~50 m) in the Gulf of Mexico
(Tolstoy et al. 2009; Diebold et al. 2010).
For deep and intermediate water cases, the field measurements
cannot be used readily to derive the harassment isopleths, as at those
sites the calibration hydrophone was located at a roughly constant
depth of 350-550 m, which may not intersect all the sound pressure
level (SPL) isopleths at their widest point from the sea surface down
to the assumed maximum relevant water depth (~2000 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 planned high-energy survey would acquire data with the 36-
airgun array at a tow depth of 9 to 12 m. For this survey, which occurs
only in deep water (>1,000 m), we use the deep-water radii obtained
from L-DEO model results down to a maximum water depth of 2,000 m for
the 36-airgun array.
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 3.
Table 3--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) \1\ Water depth (m) to the Level B
harassment
threshold
----------------------------------------------------------------------------------------------------------------
4 strings, 36 airguns, 6,600 in\3\.................. 12 >1,000 \2\ 6,733
----------------------------------------------------------------------------------------------------------------
\1\ Maximum tow depth was used for conservative distances.
\2\ Distance is based on L-DEO model results.
Table 4--Modeled Radial Distance to Isopleths Corresponding to Level A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
Low frequency Mid frequency High frequency
cetaceans cetaceans cetaceans
----------------------------------------------------------------------------------------------------------------
PTS SELcum............................................. 426.9 0 1.3
PTS Peak............................................... 38.9 13.6 268.3
----------------------------------------------------------------------------------------------------------------
The largest distance (in bold) of the dual criteria (cumulative sound exposure level (SELcum) or Peak) was used
to estimate threshold distances and potential takes by Level A harassment.
Table 4 presents the modeled PTS isopleths for each cetacean
hearing group based on L-DEO modeling incorporated in the companion
user spreadsheet, for the high-energy surveys with the shortest shot
interval (i.e. greatest potential to cause PTS based on accumulated
sound energy) (NMFS 2018).
Predicted distances to Level A harassment isopleths, which vary
based on marine mammal hearing groups, were calculated based on
modeling performed by L-DEO using the Nucleus software program and the
NMFS user spreadsheet, described below. The acoustic thresholds for
impulsive sounds 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 2016). As dual
metrics, NMFS considers onset of PTS (Level A harassment) to have
occurred when either one of the two metrics is exceeded (i.e., metric
resulting in the largest isopleth). The SEL<INF>cum</INF> metric
considers both level and duration of exposure, as well as auditory
weighting functions by marine mammal hearing group.
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
[[Page 80219]]
1 m from the array's geometrical center. However, it has been
recognized that the source level from the theoretical farfield
signature is never physically achieved at the source when the source is
an array of multiple airguns separated in space (Tolstoy et al., 2009).
Near the source (at short ranges, distances <1 km), the pulses of sound
pressure from each individual airgun in the source array do not stack
constructively as they do for the theoretical farfield signature. The
pulses from the different airguns spread out in time such that the
source levels observed or modeled are the result of the summation of
pulses from a few airguns, not the full array (Tolstoy et al., 2009).
At larger distances, away from the source array center, sound pressure
of all the airguns in the array stack coherently, but not within one
time sample, resulting in smaller source levels (a few dB) than the
source level derived from the far-field signature. Because the far-
field signature does not take into account the large array effect near
the source and is calculated as a point source, the far-field signature
is not an appropriate measure of the sound source level for large
arrays. See L-DEO's application for further detail on acoustic
modeling.
Auditory injury is unlikely to occur for mid-frequency cetaceans,
given the very small modeled zones of injury for those species (all
estimated zones are less than 15 m for mid-frequency cetaceans), in the
context of distributed source dynamics.
In consideration of the received sound levels in the near-field as
described above, we expect the potential for Level A harassment of mid-
frequency cetaceans to be de minimis, even before the likely moderating
effects of aversion and/or other compensatory behaviors (e.g.,
Nachtigall et al., 2018) are considered. We do not anticipate that
Level A harassment is a likely outcome for any mid-frequency cetacean
and do not authorize any take by Level A harassment for these species.
The Level A and Level B harassment estimates are based on a
consideration of the number of marine mammals that could be within the
area around the operating airgun array where received levels of sound
>=160 dB referenced to 1 micropascal (re 1 [micro]Pa) rms are predicted
to occur. The estimated numbers are based on the densities (numbers per
unit area) of marine mammals expected to occur in the area in the
absence of seismic surveys. To the extent that marine mammals tend to
move away from seismic sources before the sound level reaches the
criterion level and tend not to approach an operating airgun array,
these estimates likely overestimate the numbers actually exposed to the
specified level of sound.
Marine Mammal Occurrence
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations.
Habitat-based stratified marine mammal densities for the North
Atlantic are taken from the US Navy Atlantic Fleet Training and Testing
Area Marine Mammal Density (Roberts et al., 2023; Mannocci et al.,
2017), which represent the best available information regarding marine
mammal densities in the region. This density information incorporates
visual line-transect surveys of marine mammals for over 35 years,
resulting in various studies that estimated the abundance, density, and
distributions of marine mammal populations. The habitat-based density
models consisted of 5 km x 5 km grid cells. As the AFTT model does not
overlap the planned survey area, the average densities in the grid
cells for the AFTT area that encompassed a similar-sized area as the
planned survey area in the southeastern-most part of the AFTT area were
used (between ~21.1[deg] N-22.5[deg] N and ~45.1[deg] W-49.5[deg] W).
Even though these densities are for the western Atlantic Ocean, they
are for an area of the Mid-Atlantic Ridge, which would be most
representative of densities occurring at the Mid-Atlantic Ridge in the
planned survey area. More information is available online at <a href="https://seamap.env.duke.edu/models/Duke/AFTT/">https://seamap.env.duke.edu/models/Duke/AFTT/</a>.
Since there was no density data available for the actual survey
area, L-DEO used OBIS sightings, available literature, and regional
distribution maps of the actual survey area (or greater region) to
determine which species would be expected to be encountered in the
survey area. From the AFTT models, L-DEO excluded the following
species, as they were not expected to occur in the survey area: seals,
northern bottlenose whales, North Atlantic right whale (these had
densities of zero) and harbor porpoise, white-beaked dolphin, and
Atlantic white-sided dolphin (these species had non-zero densities).
There were no additional species that might occur in the survey area
that were not available in the AFTT model.
For most species, only annual densities were available. For some
baleen whale species (fin, sei and humpback whale), monthly densities
were available. For these species, the highest monthly densities were
used. Densities for fin whales were near zero and the calculations did
not result in any estimated takes. However, because this species could
be encountered in the survey area, we authorize take of one individual.
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 were then used to calculate the
area(s) around the airgun array predicted to be ensonified to sound
levels that exceed the harassment thresholds. The 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 equivalent to adding 25 percent to the planned line km
to be surveyed. The density for each species was then multiplied by the
daily ensonified areas (increased as described above) and then
multiplied by the number of survey days (11.5) to estimate potential
takes (see appendix B of L-DEO's application for more information).
L-DEO assumed that their estimates of marine mammal exposures above
harassment thresholds equate to take and requested authorization of
those takes. Those estimates in turn form the basis for our authorized
take authorization numbers. For the species for which NMFS does not
expect there to be a reasonable potential for take by Level A
harassment to occur (i.e., mid-frequency cetaceans), we have added L-
DEO's estimated exposures above Level A harassment thresholds to their
estimated exposures above the Level B harassment threshold to produce a
total number of incidents of take by Level B harassment that is
authorized. Estimated exposures and authorized take numbers are shown
in table 5.
[[Page 80220]]
Table 5--Authorized Take
--------------------------------------------------------------------------------------------------------------------------------------------------------
Estimated take Authorized take
Species ---------------------------------------------------------------- Modeled Percent of
Level B Level A Level B Level A abundance \1\ abundance \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale.......................................... 39 2 39 2 4,990 0.82
Bryde's whale........................................... 4 0 4 0 536 0.75
Minke whale \3\......................................... 23 1 23 1 13,784 0.17
Fin whale............................................... 0 0 1 0 11,672 0.01
Sei whale............................................... 11 1 11 1 19,530 0.06
Blue whale.............................................. 1 0 1 0 191 0.52
Sperm whale............................................. 110 0 110 0 64,015 0.17
Beaked whales \4\....................................... 106 0 106 0 65,069 0.16
Risso's dolphin......................................... 88 0 88 0 78,205 0.11
Rough-toothed dolphin................................... 166 0 166 0 32,848 0.51
Bottlenose dolphin...................................... 1,229 2 1,231 0 418,151 0.30
Pantropical spotted dolphin............................. 46 0 \7\ 76 0 321,740 0.02
Atlantic spotted dolphin................................ 435 1 436 0 259,519 0.17
Spinner dolphin......................................... 898 2 900 0 152,511 0.59
Striped dolphin......................................... 55 0 \7\ 73 0 412,729 0.02
Clymene dolphin......................................... 1,038 2 1,040 0 181,209 0.57
Fraser's dolphin........................................ 110 0 110 0 19,585 0.56
Common dolphin.......................................... 27 0 \7\ 92 0 473,206 0.02
Short-finned pilot whale \5\............................ 1,301 2 1,303 0 264,907 0.49
Melon-headed whale...................................... 502 1 503 0 64,114 0.78
False killer whale...................................... 99 0 99 0 12,682 0.78
Pygmy killer whale...................................... 71 0 71 0 9,001 0.79
Killer whale............................................ 1 0 \7\ 5 0 972 0.51
Kogia spp \6\........................................... 122 5 122 5 26,043 0.49
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Modeled abundance (Roberts et al. 2023) or North Atlantic abundance (NAMMCO 2023), where applicable.
\2\ Requested take authorization is expressed as percent of population for the AFTT Area only (Roberts et al. 2023).
\3\ Takes assigned equally between Common minke whales (11 Level B takes and 1 Level A take) and Antarctic minke whales (12 Level B takes).
\4\ Beaked whale guild. Includes Cuvier's beaked whale, Blaineville's beaked whale, and Gervais' beaked whale.
\5\ Takes based on density for Globicephala sp. All takes are assumed to be for short-finned pilot whales.
\6\ Kogia spp. Includes Pygmy sperm whale and Dwarf sperm whale.
\7\ Takes rounded to a mean group size (Weir 2011).
Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting the
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks, and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, NMFS
considers two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat.
This considers the nature of the potential adverse impact being
mitigated (likelihood, scope, range). It further considers the
likelihood that the measure will be effective if implemented
(probability of accomplishing the mitigating result if implemented as
planned), the likelihood of effective implementation (probability
implemented as planned), and;
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost, and impact on
operations.
Vessel-Based Visual Mitigation Monitoring
Visual monitoring requires the use of trained observers (herein
referred to as visual protected species observers (PSOs)) 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, 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 (buffer plus surrounding 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.
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
[[Page 80221]]
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 SZ and buffer zone. 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 visual 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 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 a SZ around the sound source that is clear of marine
mammals. In cases where visual monitoring is not effective (e.g., due
to weather, nighttime), acoustic monitoring may be used to allow
certain activities to occur, as further detailed below.
PAM would take place in addition to the visual monitoring program.
Visual monitoring typically is not effective during periods of poor
visibility or at night and even with good visibility, is unable to
detect marine mammals when they are below the surface or beyond visual
range. Acoustic monitoring can be used in addition to visual
observations to improve detection, identification, and localization of
cetaceans. The acoustic monitoring would serve to alert visual PSOs (if
on duty) when vocalizing cetaceans are detected. It is only useful when
marine mammals vocalize, but it can be effective either by day or by
night and does not depend on good visibility. It would be monitored in
real time so that the visual observers can be advised when cetaceans
are detected.
The R/V Langseth will use a towed PAM system, which must be
monitored by at a minimum one on duty acoustic PSO beginning at least
30 minutes prior to ramp-up and at all times during use of the airgun
array. Acoustic PSOs may be on watch for a maximum of 4 consecutive
hours followed by a break of at least 1 hour between watches and may
conduct a maximum of 12 hours of observation per 24-hour period.
Combined observational duties (acoustic and visual but not at same
time) may not exceed 12 hours per 24-hour period for any individual
PSO.
Survey activity may continue for 30 minutes when the PAM system
malfunctions or is damaged, while the PAM operator diagnoses the issue.
If the diagnosis indicates that the PAM system must be repaired to
solve the problem, operations may continue for an additional 10 hours
without acoustic monitoring during daylight hours only under the
following conditions:
<bullet> Sea state is less than or equal to BSS 4;
<bullet> No marine mammals (excluding delphinids) detected solely
by PAM in the 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
A SZ is a defined area within which occurrence of a marine mammal
triggers mitigation action intended to reduce the potential for certain
outcomes (e.g., auditory injury, disruption of critical behaviors). The
PSOs 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 expect 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,
Kogia spp, a large whale with a calf, and groups of six or more large
whales. No buffer of this extended SZ is required, as NMFS concludes
that this extended SZ is sufficiently protective to mitigate harassment
to these groups.
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
[[Page 80222]]
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, Kogia spp, a large
whale with a calf, and groups of six or more large whales) 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 the 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 stepwise 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, a large whale with a calf, and groups of six or more
large whales) 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 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
watch 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 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 the 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, and large
delphinids, such as pilot whales.
The shutdown requirement is waived for specific genera of small
dolphins if an individual is detected within the SZ. 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 the
specific genera of small dolphins (Delphinus, Lagenodelphis, Stenella,
Steno and Tursiops).
We include this small dolphin exception because shutdown
requirements for these species under all circumstances represent
practicability concerns without likely commensurate benefits for the
animals in question. Small dolphins are generally the most commonly
observed marine mammals in the specific geographic region and would
typically be the only marine mammals likely to intentionally approach
the vessel. As described above, auditory injury is extremely unlikely
to occur for mid-frequency
[[Page 80223]]
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
R/V Langseth to revisit the missed track line to reacquire data,
resulting in an overall increase in the total sound energy input to the
marine environment and an increase in the total duration over which the
survey is active in a given area. Although other mid-frequency hearing
specialists (e.g., large delphinids) are no more likely to incur
auditory injury than are small dolphins, they are much less likely to
approach vessels. Therefore, retaining a shutdown requirement for large
delphinids would not have similar impacts in terms of either
practicability for the applicant or corollary increase in sound energy
output and time on the water. We do anticipate some benefit for a
shutdown requirement for large delphinids in that it simplifies
somewhat the total range of decision-making for PSOs and may preclude
any potential for physiological effects other than to the auditory
system as well as some more severe behavioral reactions for any such
animals in close proximity to the R/V Langseth.
Visual PSOs shall use best professional judgment in making the
decision to call for a shutdown if there is uncertainty regarding
identification (i.e., whether the observed marine mammal(s) belongs to
one of the delphinid genera for which shutdown is waived or one of the
species with a larger SZ).
L-DEO must implement shutdown if a marine mammal species for which
take was not authorized or a species for which authorization was
granted but the authorized takes have been met approaches the Level A
or Level B harassment zones. L-DEO must also implement an extended
shutdown of 1,500 m 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.
Vessel Strike Avoidance Mitigation Measures
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 (separation distances stated below). Visual observers
monitoring the vessel strike avoidance zone may be third-party
observers (i.e., PSOs) or crew members, but crew members responsible
for these duties must be provided sufficient training to (1)
distinguish marine mammals from other phenomena and (2) broadly to
identify a marine mammal as a large whale (defined in this context as
sperm whales or baleen whales), or other marine mammals.
Vessel speeds must be reduced to 10 kn (18.5 kph) or less when
mother/calf pairs, pods, or large assemblages of cetaceans are observed
near a vessel. All vessels must maintain a minimum separation distance
of 100 m from sperm whales and all other baleen whales. All vessels
must, to the maximum extent practicable, attempt to maintain a minimum
separation distance of 50 m from all other marine mammals, with an
understanding that at times this may not be possible (e.g., for animals
that approach the vessel).
When marine mammals are sighted while a vessel is underway, the
vessel shall take action as necessary to avoid violating the relevant
separation distance (e.g., attempt to remain parallel to the animal's
course, avoid excessive speed or abrupt changes in direction until the
animal has left the area). If marine mammals are sighted within the
relevant separation distance, the vessel must reduce speed and shift
the engine to neutral, not engaging the engines until animals are clear
of the area. This does not apply to any vessel towing gear or any
vessel that is navigationally constrained.
Based on our evaluation of the applicant's measures, as well as
other measures considered by NMFS, NMFS has determined that the
mitigation measures provide the means of effecting the least
practicable impact on the affected species or stocks and their habitat,
paying particular attention to rookeries, mating grounds, and areas of
similar significance.
Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing 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.
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 advance
approval (prior to embarking on the vessel).
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.
Monitoring and reporting requirements prescribed by NMFS
[[Page 80224]]
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 R/V 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 reticle
binoculars (e.g., 25 x 150; 2.7 view angle; individual ocular focus;
height control) of appropriate quality solely for PSO use. These
binoculars 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;
<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:
[cir] Vessel name, vessel size and type, maximum speed capability
of vessel;
[cir] Dates (MM/DD/YYYY) of departures and returns to port with
port name;
[cir] PSO names and affiliations, PSO ID (initials or other
identifier);
[cir] Date (MM/DD/YYYY) and participants of PSO briefings;
[cir] Visual monitoring equipment used (description);
[cir] PSO location on vessel and height (meters) of observation
location above water surface;
[cir] Watch status (description);
[cir] Dates (MM/DD/YYYY) and times (Greenwich Mean Time/UTC) of
survey on/off effort and times (GMC/UTC) corresponding with PSO on/off
effort;
[cir] Vessel location (decimal degrees) when survey effort began
and ended and vessel location at beginning and end of visual PSO duty
shifts;
[cir] Vessel location (decimal degrees) at 30-second intervals if
obtainable from data collection software, otherwise at practical
regular interval;
[cir] Vessel heading (compass heading) and speed (knots) at
beginning and end of visual PSO duty shifts and upon any change;
[cir] Water depth (meters) (if obtainable from data collection
software);
[cir] Environmental conditions while on visual survey (at beginning
and end of PSO shift and whenever conditions changed significantly),
including BSS and any other relevant weather conditions including cloud
cover, fog, sun glare, and overall visibility to the horizon;
[cir] Factors that may have contributed to impaired observations
during each PSO shift change or as needed as environmental conditions
changed (description) (e.g., vessel traffic, equipment malfunctions);
and
[cir] Vessel/Survey activity information (and changes thereof)
(description),
[[Page 80225]]
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:
[cir] Sighting ID (numeric);
[cir] Watch status (sighting made by PSO on/off effort,
opportunistic, crew, alternate vessel/platform);
[cir] Location of PSO/observer (description);
[cir] Vessel activity at the time of the sighting (e.g., deploying,
recovering, testing, shooting, data acquisition, other);
[cir] PSO who sighted the animal/ID;
[cir] Time/date of sighting (GMT/UTC, MM/DD/YYYY);
[cir] Initial detection method (description);
[cir] Sighting cue (description);
[cir] Vessel location at time of sighting (decimal degrees);
[cir] Water depth (meters);
[cir] Direction of vessel's travel (compass direction);
[cir] Speed (knots) of the vessel from which the observation was
made;
[cir] Direction of animal's travel relative to the vessel
(description, compass heading);
[cir] Bearing to sighting (degrees);
[cir] Identification of the animal (e.g., genus/species, lowest
possible taxonomic level, or unidentified) and the composition of the
group if there is a mix of species;
[cir] Species reliability (an indicator of confidence in
identification) (1 = unsure/possible, 2 = probable, 3 = definite/sure,
9 = unknown/not recorded);
[cir] Estimated distance to the animal (meters) and method of
estimating distance;
[cir] Estimated number of animals (high/low/best) (numeric);
[cir] Estimated number of animals by cohort (adults, yearlings,
juveniles, calves, group composition, etc.);
[cir] Description (as many distinguishing features as possible of
each individual seen, including length, shape, color, pattern, scars or
markings, shape and size of dorsal fin, shape of head, and blow
characteristics);
[cir] Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding,
traveling; as explicit and detailed as possible; note any observed
changes in behavior);
[cir] Animal's closest point of approach (meters) and/or closest
distance from any element of the airgun array;
[cir] Description of any actions implemented in response to the
sighting (e.g., delays, shutdown, ramp-up) and time and location of the
action.
[cir] Photos (Yes/No);
[cir] Photo Frame Numbers (List of numbers); and
[cir] Conditions at time of sighting (Visibility; Beaufort Sea
State).
If a marine mammal is detected while using the PAM system, the
following information should be recorded:
<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
L-DEO shall submit a draft comprehensive report on all activities
and monitoring results within 90 days of the completion of the survey
or expiration of the IHA, whichever comes sooner. The report must
describe all activities conducted and sightings of marine mammals, must
provide full documentation of methods, results, and interpretation
pertaining to all monitoring, and must summarize the dates and
locations of survey operations and all marine mammal sightings (dates,
times, locations, activities, associated survey activities). The draft
report shall also include geo-referenced time-stamped vessel tracklines
for all time periods during which airgun arrays were operating.
Tracklines should include points recording any change in airgun array
status (e.g., when the sources began operating, when they were turned
off, or when they changed operational status such as from full array to
single gun or vice versa). Geographic Information System files shall be
provided in Environmental Systems Research Institute shapefile format
and include the UTC date and time, latitude in decimal degrees, and
longitude in decimal degrees. All coordinates shall be referenced to
the WGS84 geographic coordinate system. In addition to the report, all
raw observational data shall be made available. The report must
summarize data collected as described above. A final report must be
submitted within 30 days following resolution of any comments on the
draft report.
The report must include a validation document concerning the use of
PAM, which should include necessary noise validation diagrams and
demonstrate whether background noise levels on the PAM deployment
limited achievement of the planned detection goals. Copies of any
vessel self-noise assessment reports must be included with the report.
Reporting Injured or Dead Marine Mammals
Discovery of injured or dead marine mammals--In the event that
personnel involved in the survey activities discover an injured or dead
marine mammal, the L-DEO shall report the incident to the Office of
Protected Resources (OPR) 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 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;
[[Page 80226]]
<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).
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 harassment, resulting
from temporary avoidance of the area or decreased foraging (if such
activity was occurring), reactions that are considered to be of low
severity and with no lasting biological consequences (e.g., Southall et
al., 2007).
We are authorizing a limited number of Level A harassment events of
five species in the form of PTS (humpback whale, minke whale, sei
whale, and Kogia spp (i.e., pygmy and dwarf sperm whales)) and Level B
harassment of all 28 marine mammal species (table 5. If any PTS is
incurred in marine mammals as a result of the specified 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 R/V
Langseth and of the marine mammals in the project areas, as well as the
fact that the vessel is not expected to remain in any one area in which
individual marine mammals would be expected to concentrate for an
extended period of time. Additionally, L-DEO would shut down the airgun
array if marine mammals approach within 500 m (with the exception of
specific genera of dolphins, see Mitigation), further reducing the
expected duration and intensity of sound and therefore, the likelihood
of marine mammals incurring PTS. Since the duration of exposure to loud
sounds will be relatively short, it 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 R/V
Langseth's approach due to the vessel's relatively low speed when
conducting seismic surveys.
In addition, the maximum expected Level B harassment zone around
the survey vessel is 6,733 m. 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 (11.5 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 marine mammal prey species are not expected to cause
significant or long-term fitness consequences for individual marine
mammals or their populations.
Additionally, the acoustic ``footprint'' of the planned survey
would be very small relative to the ranges of all marine mammals that
would potentially be affected. Sound levels would increase in the
marine environment in a relatively small area surrounding the vessel
compared to the range of the marine mammals within the survey area. The
seismic array would be active 24 hours per day throughout the duration
of the survey. However, the very brief overall duration of the survey
(30 survey days) would further limit potential impacts that may occur
as a result of the activity.
Of the marine mammal species that are likely to occur in the
project area, the following species are listed as endangered under the
ESA: blue whales, fin whales, sei whales, and sperm whales. The take
numbers authorized for these species (table 5) are minimal relative to
their modeled population sizes; therefore, we do not expect population-
level impacts to any of these species. Moreover, the actual range of
the populations extends past the area covered by the model, so modeled
population sizes are likely smaller than their actual population size.
The other marine mammal species that may be taken by harassment during
L-DEO's seismic survey are not listed as threatened or endangered under
the ESA. There is no designated critical habitat for any ESA-listed
marine mammals within the project area.
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.
The mitigation measures are expected to reduce, to the extent
practicable, the intensity and/or duration of takes for all species
listed in table 1. 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
[[Page 80227]]
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 populations
through effects on annual rates of recruitment or survival:
<bullet> No serious injury or mortality is anticipated or
authorized;
<bullet> We are authorizing a limited number of Level A harassment
events of five species in the form of PTS; if any PTS is incurred as a
result of the specified 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 vessel 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.
<bullet> The activity is temporary and of relatively short duration
(11.5 days of planned survey activity);
<bullet> The vast majority of anticipated impacts of the activity
on marine mammals would be temporary behavioral changes due to
avoidance of the ensonified area, which is relatively small (see table
3);
<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
and severity of takes, to the extent practicable, by visually and/or
acoustically detecting marine mammals within the established zones and
implementing corresponding mitigation measures (e.g., delay; shutdown).
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 marine mammal take from the activity will
have a negligible impact on all affected marine mammal species or
populations.
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 number of takes NMFS is authorizing is below one-third of the
most appropriate abundance estimate for all relevant populations
(specifically, take of individuals is less than 1 percent of the
modeled abundance of each affected population, see table 5). This is
conservative because the modeled abundance represents a population of
the species and we assume all takes are of different individual
animals, which is likely not the case. Some individuals may be
encountered multiple times in a day, but PSOs would count them as
separate individuals if they cannot be identified.
Based on the analysis contained herein of the planned activity
(including the mitigation and monitoring measures) and the anticipated
take of marine mammals, NMFS finds that small numbers of marine mammals
would be taken relative to the population size of the affected species
or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.
Endangered Species Act
Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.)
requires that each Federal agency insure that any action it authorizes,
funds, or carries out is not likely to jeopardize the continued
existence of any endangered or threatened species or result in the
destruction or adverse modification of designated critical habitat. To
ensure ESA compliance for the issuance of IHAs, NMFS consults
internally whenever we propose to authorize take for endangered or
threatened species
The NMFS OPR ESA Interagency Cooperation Division issued a
Biological Opinion under section 7 of the ESA, on the issuance of an
IHA to NSF under section 101(a)(5)(D) of the MMPA by the NMFS OPR
Permits and Conservation Division. The Biological Opinion concluded
that the action is not likely to jeopardize the continued existence of
ESA-listed blue whales, fin whales, sei whales, and sperm whales. There
is no designated critical habitat in the action area for any ESA-listed
marine mammal species.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our action (i.e., the issuance of an IHA) with respect
to potential impacts on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or
mortality) of the Companion Manual for NAO 216-6A, which do not
individually or cumulatively have the potential for significant impacts
on the quality of the human environment and for which we have not
identified any extraordinary circumstances that would preclude this
categorical exclusion. Accordingly, NMFS has determined that the
issuance of the IHA qualifies to be categorically excluded from further
NEPA review.
Authorization
NMFS has issued an IHA to L-DEO for the potential harassment of
small numbers of 28 marine mammal species incidental to the marine
geophysical survey at the Chain Transform Fault in the equatorial
Atlantic Ocean that includes the previously explained mitigation,
monitoring and reporting requirements.
Dated: September 27, 2024.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2024-22724 Filed 10-1-24; 8:45 am]
BILLING CODE 3510-22-P
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