Notice2022-14362
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Geophysical Surveys in the Southeastern Gulf of Mexico
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
July 6, 2022
Effective
June 29, 2022
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 IHA to Scripps Institution of Oceanography (Scripps) to incidentally harass marine mammals during marine geophysical surveys in the southeastern Gulf of Mexico.
Full Text
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<title>Federal Register, Volume 87 Issue 128 (Wednesday, July 6, 2022)</title>
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[Federal Register Volume 87, Number 128 (Wednesday, July 6, 2022)]
[Notices]
[Pages 40186-40200]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-14362]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XB760]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Geophysical Surveys in the
Southeastern Gulf of Mexico
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; issuance of an incidental harassment authorization
(IHA).
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SUMMARY: In accordance with the regulations implementing the Marine
Mammal Protection Act (MMPA) as amended, notification is hereby given
that NMFS has issued an IHA to Scripps Institution of Oceanography
(Scripps) to incidentally harass marine mammals during marine
geophysical surveys in the southeastern Gulf of Mexico.
DATES: This authorization is effective from June 29, 2022 through June
28, 2023.
FOR FURTHER INFORMATION CONTACT: Amy Fowler, Office of Protected
Resources, NMFS, (301) 427-8401. Electronic copies of the application
and supporting documents, as well as a list of the references cited in
this document, may be obtained online at: <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a>. In case of problems accessing these
documents, please call the contact listed above.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and either regulations
are proposed or, if the taking is limited to harassment, a notice of a
proposed incidental harassment authorization is provided to the public
for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking and other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
taking for certain subsistence uses (referred to in shorthand as
``mitigation''); and requirements pertaining to the mitigation,
monitoring and reporting of the takings are set forth.
The definitions of all applicable MMPA statutory terms cited above
are included in the relevant sections below.
Summary of Request
On March 17, 2020, NMFS received a request from Scripps for an IHA
to take marine mammals incidental to low-energy geophysical surveys in
the southeastern Gulf of Mexico, initially planned to occur in summer
2020. The application was deemed adequate and complete on May 26, 2020.
On June 9, 2020, Scripps notified NMFS that the proposed survey had
been postponed and tentatively rescheduled for summer 2021. On April 8,
2021, Scripps notified NMFS that the survey had been further postponed
and is now expected to occur in July-August 2022. NMFS reviewed recent
draft Stock Assessment Reports (SARs) and other scientific literature,
and determined that neither this nor any other new information affects
which species or stocks have the potential to be affected, the
potential effects to marine mammals and their habitat as described in
the IHA application, or any other aspect of the analysis. Therefore,
NMFS determined that Scripps' IHA application remained adequate and
complete. Scripps' request is for take of 20 species of marine mammals
by Level B harassment only. Neither Scripps nor NMFS expects serious
injury or mortality to result from this activity and, therefore, an IHA
is appropriate.
Description of Activity
Overview
Scripps plans to support a research project that involves low-
energy seismic surveys in the Gulf of Mexico during summer 2022. The
study will be conducted on the R/V Justo Sierra, owned by Universidad
Nacional Aut[oacute]noma de M[eacute]xico (UNAM), using a portable
multi-channel seismic (MCS) system operated by marine technicians from
Scripps. The survey will use a pair of low-energy Generator-Injector
(GI) airguns with a total discharge volume of 90 cubic inches (in\3\).
The surveys will take place within the Exclusive Economic Zones (EEZs)
of Mexico and Cuba in the southeastern Gulf of Mexico.
Dates and Duration
The specific dates of the survey have not been determined but the
cruise is expected to occur in July to August 2022. The research cruise
is expected to consist of 15 days at sea, including ~12 days of seismic
operations (10 planned days and 2 contingency days) and ~3 days of
transit. R/V Justo Sierra will depart from Tampamochaco, Mexico
[[Page 40187]]
and return to Progreso, Mexico after the program is completed.
Specific Geographic Region
The planned surveys take place in the Gulf of Mexico between
~22[deg]-25[deg] N and 83.8[deg]-88[deg] W (see Figure 1). Seismic
acquisition will occur in two primary survey areas. The Yucat[aacute]n
Channel survey area is located in the deep-water channel between the
Campeche and Florida escarpments, within the EEZ of Cuba in water
depths ranging from ~1,500 to 3,600 meters (m; 4,921 to 11,811 feet
(ft)). The Campeche Bank survey area is located in the northeastern
flank of the Campeche escarpment, within the EEZs of Cuba and Mexico in
waters ranging in depth from ~110 to 3,000 m (361 to 9,843 ft).
[GRAPHIC] [TIFF OMITTED] TN06JY22.007
A detailed description of the planned geophysical survey project is
provided in the Federal Register notice for the proposed IHA (86 FR
71427; December 16, 2021). Since that time, no changes have been made
to the planned survey activities. Therefore, a detailed description is
not provided here. Please refer to that Federal Register notice for the
description of the specified activity.
Mitigation, monitoring, and reporting measures are described in
detail later in this document (please see Mitigation and Monitoring and
Reporting).
Comments and Responses
A notice of proposed IHA was published in the Federal Register on
December 16, 2021 (86 FR 71427). That notice described, in detail,
Scripps' activity, the marine mammal species that may be affected by
the activity, and the anticipated effects on marine mammals. During the
30-day public comment period, NMFS did not receive any public comments.
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the application summarize available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history, of the potentially affected species.
Additional information regarding population trends and threats may be
found in NMFS's SARs (<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's website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
Table 1 lists all species or stocks for which take is expected and
has been authorized for this action, and summarizes information related
to the population or stock, including regulatory status under the MMPA
and Endangered Species Act (ESA) and potential biological removal
(PBR), where known. For taxonomy, we follow Committee on Taxonomy
(2021). PBR is defined by the MMPA as the maximum number of animals,
not including natural mortalities, that may be removed from a marine
mammal stock while allowing that stock to reach or maintain its optimum
sustainable population (as described in NMFS's SARs). While no
mortality is anticipated or authorized here, PBR and annual serious
injury and mortality from anthropogenic sources are included here as
gross indicators of the status of the species and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS's stock
[[Page 40188]]
abundance estimates for most species represent the total estimate of
individuals within the geographic area, if known, that comprises that
stock. For most species, stock abundance estimates are based on
sightings within the U.S. EEZ, however for some species, this
geographic area may extend beyond U.S. waters. Other species may use
survey abundance estimates. Survey abundance (as compared to stock or
species abundance) is the total number of individuals estimated within
the survey area, which may or may not align completely with a stock's
geographic range as defined in the SARs. These surveys may also extend
beyond U.S. waters. In this case, the planned survey area outside of
the U.S. EEZ does not necessarily overlap with the ranges for stocks
managed by NMFS. However, we assume that individuals of these species
that may be encountered during the survey may be part of those stocks.
All managed stocks in this region are assessed in NMFS's U.S.
Atlantic and Gulf of Mexico SARs (e.g., Hayes et al., 2021). All values
presented in Table 1 are the most recent available at the time of
publication and are available in the 2020 SARs (Hayes et al., 2021) and
draft 2021 SARs (available online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports</a>).
For the majority of species potentially present in the specified
geographical region, NMFS has designated only a single generic stock
(i.e., ``Gulf of Mexico'') for management purposes, although there is
currently no information to differentiate the stock from the Atlantic
Ocean stock of the same species, nor information on whether more than
one stock may exist in the GOM (Hayes et al., 2017).
Table 1--Marine Mammals That Could Occur in the Survey Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gulf of
Stock abundance Mexico
ESA/MMPA (CV, Nmin, most population
Common name Scientific name Stock status; recent abundance PBR Annual M/SI abundance
strategic (Y/ survey) \2\ \3\ (Roberts et
N) \1\ al., 2016)
\4\
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Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
Sperm whale................ Physeter Gulf of Mexico.... E/D; Y 1,180 (0.22, 983, 2................. 9.6 2,207
macrocephalus. 2018).
Family Kogiidae:
Pygmy sperm whale \6\...... Kogia breviceps... Gulf of Mexico.... -/-; N 336 (0.35, 253, 2.5............... 31 4,373
2018).
Dwarf sperm whale \6\...... Kogia sima........
Family Ziphiidae (beaked
whales):
Cuvier's beaked whale \6\.. Ziphius cavirstris Gulf of Mexico.... -/-; N 18 (0.75, 10, 0.1............... 5.2 3,768
2018).
Blainville's beaked whale Mesoplodon Gulf of Mexico.... -/-; N 98 (0.46, 68, 0.7............... 5.2
\6\. densirostris. 2018).
Gervais' beaked whale \6\.. Mesoplodon Gulf of Mexico.... -/-; N 20 (0.98, 10, 0.1............... 5.2
europaeus. 2018).
Family Delphinidae:
Rough-toothed dolphin...... Steno bredanensis. Gulf of Mexico.... -/-; N unknown (n/a, undetermined...... 39 4,853
unknown, 2018).
Bottlenose dolphin......... Tursiops truncatus Gulf of Mexico -/-; N 7,462 (0.31, 58................ 32 \6\ 176,108
Oceanic. 5,769, 2018).
Pantropical spotted dolphin Stenella attenuata Gulf of Mexico.... -/-; N 37,195 (0.24, 304............... 241 102,361
30,377, 2018).
Atlantic spotted dolphin... Stenella frontalis Gulf of Mexico.... -/-; N 21,506 (0.26, 166............... 36 74,785
17,339, 2018).
Spinner dolphin............ Stenella Gulf of Mexico.... -/-; Y 2,991 (0.54, 20................ 113 25,114
longirostris. 1,954, 2018).
Clymene dolphin............ Stenella clymene.. Gulf of Mexico.... -/-; Y 513 (1.03, 250, 2.5............... 8.4 11,895
2018).
Striped dolphin............ Stenella Gulf of Mexico.... -/-; Y 1,817 (0.56, 12................ 13 5,229
coeruleoalba. 1,172, 2018).
Fraser's dolphin........... Lagenodelphis Gulf of Mexico.... -/-; N 213 (1.03, 104, 1................. Unknown 1,665
hosei. 2018).
Risso's dolphin............ Grampus griseus... Gulf of Mexico.... -/-; N 1,974 (0.46, 14................ 5.3 3,764
1,368, 2018).
Melon-headed whale......... Peponocephala Gulf of Mexico.... -/-; N 1,749 (0.68, 10................ 9.5 7,003
electra. 1,039, 2018).
Pygmy killer whale......... Feresa attenuata.. Gulf of Mexico.... -/-; N 613 (1.15, 283, 2.8............... 1.6 2,126
2018).
False killer whale......... Pseudorca Gulf of Mexico.... -/-; N 494 (0.79, 276, 2.8............... Unknown 3,204
crassidens. 2018).
Killer whale............... Orcinus orca...... Gulf of Mexico.... -/-; N 267 (0.75, 152, 1.5............... Unknown 185
2018).
Short-finned pilot whale... Globicephalus Gulf of Mexico.... -/-; N 1,321 (0.43, 934, 7.5............... 3.9 1,981
macrorhynchus. 2018).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports</a>. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, ship strike). Annual mortality/serious injury (M/SI) often cannot be determined precisely and is in some cases presented as a
minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ This information represents species- or guild-specific best abundance estimate predicted by habitat-based cetacean density models (Roberts et al.,
2016). These models provide the best available scientific information regarding predicted density patterns of cetaceans in the U.S. Gulf of Mexico,
and we provide the corresponding abundance predictions as a point of reference. Total abundance estimates were produced by computing the mean density
of all pixels in the modeled area and multiplying by its area. For those taxa where a density surface model predicting abundance by month was
produced, the maximum mean seasonal abundance was used. For those taxa where abundance is not predicted by month, only mean annual abundance is
available. For more information, see <a href="https://seamap.env.duke.edu/models/Duke/GOM/">https://seamap.env.duke.edu/models/Duke/GOM/</a>.
\5\ Abundance estimates are in some cases reported for a guild or group of species when those species are difficult to differentiate at sea. Similarly,
the habitat-based cetacean density models produced by Roberts et al. (2016) are based in part on available observational data which, in some cases, is
limited to genus or guild in terms of taxonomic definition. NMFS's SARs present pooled abundance estimates for Kogia spp. and Mesoplodon spp., while
Roberts et al. (2016) produced density models to genus level for Kogia spp. and as a guild for beaked whales (Ziphius cavirostris and Mesoplodon
spp.). Finally, Roberts et al. (2016) produced a density model for bottlenose dolphins that does not differentiate between oceanic, shelf, and coastal
stocks.
[[Page 40189]]
In Table 1 above, we report two sets of abundance estimates: those
from NMFS SARs and those predicted by Roberts et al. (2016). Please see
the table footnotes for more detail. As discussed in the notice of
proposed IHA (86 FR 71427; December 16, 2021), we expect that the
Roberts et al. (2016) estimates are generally more realistic and, for
these purposes, represent the best available information. For purposes
of assessing estimated exposures relative to abundance--used in this
case to understand the scale of the predicted takes compared to the
population--we generally believe that the Roberts et al. (2016)
abundance predictions are most appropriate because they were used to
generate the exposure estimates and therefore provide the most relevant
comparison (see Estimated Take). Roberts et al. (2016) represents the
best available scientific information regarding marine mammal
occurrence and distribution in the Gulf of Mexico.
As the planned survey lines are outside of the U.S. EEZ, they do
not directly overlap with the defined stock ranges within the Gulf of
Mexico (Hayes et al., 2021). However, some of the survey lines occur
near the U.S. EEZ, and the distribution and abundance of species in
U.S. EEZ waters are assumed representative of those in the survey area.
As indicated above, all 20 species (with 20 representative stocks in
the northern Gulf of Mexico) in Table 1 temporally and spatially co-
occur with the activity to the degree that take is reasonably likely to
occur, and we have authorized it. All species that could potentially
occur in the planned survey areas are included in Table 2 of the IHA
application.
A detailed description of the species likely to be affected by the
geophysical surveys, including brief introductions to the species and
relevant stocks as well as available information regarding population
trends and threats, and information regarding local occurrence, were
provided in Scripps' IHA application and summarized in the Federal
Register notice for the proposed IHA (86 FR 71427; December 16, 2021);
since that time, we are not aware of any changes in the status of these
species or stocks; therefore, detailed descriptions are not provided
here. Please refer to that Federal Register notice and the IHA
application for these descriptions. Please also refer to NMFS' website
(<a href="http://www.nmfs.noaa.gov/pr/species/mammals/">www.nmfs.noaa.gov/pr/species/mammals/</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. Current data indicate that not all marine
mammal species have equal hearing capabilities (e.g., Richardson et
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect
this, Southall et al. (2007) recommended that marine mammals be divided
into functional hearing groups based on directly measured or estimated
hearing ranges on the basis of available behavioral response data,
audiograms derived using auditory evoked potential techniques,
anatomical modeling, and other data. Note that no direct measurements
of hearing ability have been successfully completed for mysticetes
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described
generalized hearing ranges for these marine mammal hearing groups.
Generalized hearing ranges were chosen based on the approximately 65
decibel (dB) threshold from the normalized composite audiograms, with
the exception for lower limits for low-frequency cetaceans where the
lower bound was deemed to be biologically implausible and the lower
bound from Southall et al. (2007) retained. Marine mammal hearing
groups and their associated hearing ranges are provided in Table 2.
Table 2--Marine Mammal Hearing Groups
[NMFS, 2018]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
High-frequency (HF) cetaceans (true 275 Hz to 160 kHz.
porpoises, Kogia, river dolphins,
cephalorhynchid, Lagenorhynchus
cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) 50 Hz to 86 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 39 kHz.
(sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on ~65 dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al. 2007) and PW pinniped (approximation).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
Twenty species of cetacean have the reasonable potential to co-occur
with the planned survey activities. No pinnipeds are expected to be
present or taken. Of the cetacean species that may be present, 18 are
classified as mid-frequency cetaceans (i.e., all delphinid and ziphiid
species and the sperm whale) and two are classified as high-frequency
cetaceans (i.e., Kogia spp.). No low-frequency cetaceans (i.e., baleen
whales) are expected to be present or taken.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
The effects of underwater noise from Scripps' geophysical survey
activities have the potential to result in behavioral harassment of
marine mammals in the vicinity of the survey area. The notice of
proposed IHA (86 FR 71427; December 16, 2021) included a discussion of
the effects of anthropogenic noise on marine mammals and the potential
effects of underwater noise from Scripps' geophysical survey activities
on marine mammals and their habitat. That information and analysis is
incorporated by reference into this final IHA determination and is not
repeated here; please refer to the notice of proposed IHA (86 FR 71427;
December 16, 2021). The referenced information includes a summary and
discussion of the ways that the specified activity may impact marine
mammals and their habitat. Consistent with the analysis in our prior
Federal Register notices for similar Scripps surveys and after
independently evaluating the analysis in Scripps'
[[Page 40190]]
application, we determine that the survey is likely to result in the
takes described in the Estimated Take section of this document and that
other forms of take are not expected to occur.
The Estimated Take section later in this document includes a
quantitative analysis of the number of individuals that are expected to
be taken by this activity. The Negligible Impact Analysis and
Determination section considers the content of this section, the
Estimated Take section, and the Mitigation section, to draw conclusions
regarding the likely impacts of these activities on the reproductive
success or survivorship of individuals and how those impacts on
individuals are likely to impact marine mammal species or stocks.
Estimated Take
This section provides an estimate of the number of incidental takes
authorized through this IHA, which informs both NMFS' consideration of
``small numbers'' and the negligible impact determination.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Authorized takes are by Level B harassment only, as use of the
acoustic sources (i.e., seismic airgun) has the potential to result in
disruption of behavioral patterns for individual marine mammals. Based
on the nature of the activity and the anticipated effectiveness of the
mitigation measures (i.e., marine mammal exclusion zones) discussed in
detail below in Mitigation section, Level A harassment is neither
anticipated nor authorized. As described previously, no mortality is
anticipated or authorized for this activity. Below we describe how the
take is estimated.
Generally speaking, we estimate take by considering: (1) acoustic
thresholds above which NMFS believes the best available science
indicates marine mammals will be behaviorally harassed or incur some
degree of permanent hearing impairment; (2) the area or volume of water
that will be ensonified above these levels in a day; (3) the density or
occurrence of marine mammals within these ensonified areas; and, (4)
the number of days of activities. We note that while these basic
factors can contribute to a basic calculation to provide an initial
prediction of takes, additional information that can qualitatively
inform take estimates is also sometimes available (e.g., previous
monitoring results or average group size). Below, we describe the
factors considered here in more detail and present the estimated and
authorized take.
Acoustic Thresholds
NMFS recommends the use of acoustic thresholds that identify the
received level of underwater sound above which exposed marine mammals
would be reasonably expected to be behaviorally harassed (equated to
Level B harassment) or to incur PTS of some degree (equated to Level A
harassment).
Level B Harassment for non-explosive sources--Though significantly
driven by received level, the onset of behavioral disturbance from
anthropogenic noise exposure is also informed to varying degrees by
other factors related to the source (e.g., frequency, predictability,
duty cycle), the environment (e.g., bathymetry), and the receiving
animals (hearing, motivation, experience, demography, behavioral
context) and can be difficult to predict (Southall et al., 2007,
Ellison et al., 2012). Based on what the available science indicates
and the practical need to use a threshold based on a factor that is
both predictable and measurable for most activities, NMFS uses a
generalized acoustic threshold based on received level to estimate the
onset of behavioral harassment. NMFS predicts that marine mammals are
likely to be behaviorally harassed in a manner we consider Level B
harassment when exposed to underwater anthropogenic noise above
received levels of 120 dB re 1 microPascal ([mu]Pa) root mean square
(rms) for continuous (e.g., vibratory pile-driving, drilling) and above
160 dB re 1 [mu]Pa (rms) for non-explosive impulsive (e.g., seismic
airguns) or intermittent (e.g., scientific sonar) sources.
Scripps' activity includes the use of impulsive seismic sources,
and therefore the 160 dB re 1 [mu]Pa (rms) is applicable.
Level A harassment for non-explosive sources--NMFS' Technical
Guidance for Assessing the Effects of Anthropogenic Sound on Marine
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual
criteria to assess auditory injury (Level A harassment) to five
different marine mammal groups (based on hearing sensitivity) as a
result of exposure to noise from two different types of sources
(impulsive or non-impulsive). Scripps' activity includes the use of
impulsive seismic sources.
These thresholds are provided in the table below. The references,
analysis, and methodology used in the development of the thresholds are
described in NMFS 2018 Technical Guidance, which may be accessed at
<a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance</a>.
Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift (PTS)
----------------------------------------------------------------------------------------------------------------
PTS onset acoustic thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 219 dB; Cell 2: LE,LF,24h; 199 dB.
LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans........... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,MF,24h; 198 dB.
LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.......... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,HF,24h; 173 dB.
LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 218 dB; Cell 8: LE,PW,24h; 201 dB.
LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 232 dB; Cell 10: LE,OW,24h; 219 dB.
LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
thresholds associated with impulsive sounds, these thresholds should also be considered.
[[Page 40191]]
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as
incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript
``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted within the
generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates
the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds)
and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could
be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible,
it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that will feed into identifying the area ensonified above the
acoustic thresholds, which include source levels and transmission loss
coefficient.
The survey entails the use of a 2-airgun array with a total
discharge of 90 in\3\ at a tow depth of 2-4 m. Lamont-Doherty Earth
Observatory (L-DEO) model results are used to determine the 160
dB<INF>rms</INF> radius for the 2-airgun array in deep water (> 1,000
m) down to a maximum water depth of 2,000 m. Received sound levels were
predicted by L-DEO's model (Diebold et al., 2010) as a function of
distance from the airguns, for the two 45 in\3\ airguns. This modeling
approach uses ray tracing for the direct wave traveling from the array
to the receiver and its associated source ghost (reflection at the air-
water interface in the vicinity of the array), in a constant-velocity
half-space (infinite homogenous ocean layer, unbounded by a seafloor).
In addition, propagation measurements of pulses from a 36-airgun array
at a tow depth of 6 m have been reported in deep water (~1,600 m),
intermediate water depth on the slope (~600-1,100 m), and shallow water
(~50 m) in the Gulf of Mexico in 2007-2008 (Tolstoy et al., 2009;
Diebold et al., 2010).
For deep and intermediate water cases, the field measurements
cannot be used readily to derive the Level A and Level B harassment
isopleths, as at those sites the calibration hydrophone was located at
a roughly constant depth of 350-550 m, which may not intersect all the
sound pressure level (SPL) isopleths at their widest point from the sea
surface down to the maximum relevant water depth (~2,000 m) for marine
mammals. At short ranges, where the direct arrivals dominate and the
effects of seafloor interactions are minimal, the data at the deep
sites are suitable for comparison with modeled levels at the depth of
the calibration hydrophone. At longer ranges, the comparison with the
model--constructed from the maximum SPL through the entire water column
at varying distances from the airgun array--is the most relevant.
In deep and intermediate water depths, comparisons at short ranges
between sound levels for direct arrivals recorded by the calibration
hydrophone and model results for the same array tow depth are in good
agreement (see Figures 12 and 14 in Appendix H of NSF-USGS 2011).
Consequently, isopleths falling within this domain can be predicted
reliably by the L-DEO model, although they may be imperfectly sampled
by measurements recorded at a single depth. At greater distances, the
calibration data show that seafloor-reflected and sub-seafloor-
refracted arrivals dominate, whereas the direct arrivals become weak
and/or incoherent. Aside from local topography effects, the region
around the critical distance is where the observed levels rise closest
to the model curve. However, the observed sound levels are found to
fall almost entirely below the model curve. Thus, analysis of the Gulf
of Mexico calibration measurements demonstrates that although simple,
the L-DEO model is a robust tool for conservatively estimating
isopleths.
The planned surveys will acquire data with two 45-in\3\ guns at a
tow depth of 2-4 m. For deep water (>1000 m), we use the deep-water
radii obtained from L-DEO model results down to a maximum water depth
of 2,000 m for the airgun array with 2-m airgun separation. The radii
for intermediate water depths (100-1,000 m) are derived from the deep-
water ones by applying a correction factor (multiplication) of 1.5,
such that observed levels at very near offsets fall below the corrected
mitigation curve (see Figure 16 in Appendix H of NSF-USGS 2011). No
survey effort is planned to occur in shallow water (<100 m).
L-DEO's modeling methodology is described in greater detail in
SIO's IHA application. The estimated distances to the Level B
harassment isopleths for the planned airgun configuration in each water
depth category are shown in Table 4.
Table 4--Predicted Radial Distances From R/V Justo Sierra Seismic Source
to Isopleths Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
Predicted
distances (m)
Airgun configuration Water depth to 160 dB rms
(m) SPL received
sound level
------------------------------------------------------------------------
Two 45 in\3\ guns, 2-m separation, 4-m >1,000 \a\ 539
tow depth.............................. 100-1,000 \b\ 809
------------------------------------------------------------------------
\a\ Distance based on L-DEO model results.
\b\ Distance based on L-DEO model results with a 1.5 x correction factor
between deep and intermediate water depths.
Predicted distances to Level A harassment isopleths, which vary
based on marine mammal hearing groups, were calculated based on
modeling performed by L-DEO using the NUCLEUS software program and the
NMFS User Spreadsheet. The updated acoustic thresholds for onset of
hearing impacts from impulsive sounds (e.g., airguns) contained in the
Technical Guidance were presented as dual metric acoustic thresholds
using both cumulative sound exposure level (SEL<INF>cum</INF>) and peak
sound pressure metrics (NMFS 2016a). As dual metrics, NMFS considers
onset of PTS (Level A harassment) to have occurred when either one of
the two metrics is exceeded (i.e., metric resulting in the largest
isopleth). The SEL<INF>cum</INF> metric considers both level and
duration of exposure, as well as auditory weighting functions by marine
mammal hearing group. In recognition of the fact that the
[[Page 40192]]
requirement to calculate Level A harassment ensonified areas could be
more technically challenging to predict due to the duration component
and the use of weighting functions in the new SEL<INF>cum</INF>
thresholds, NMFS developed an optional User Spreadsheet that includes
tools to help predict a simple isopleth that can be used in conjunction
with marine mammal density or occurrence to facilitate the estimation
of take numbers.
The SEL<INF>cum</INF> for the 2-GI airgun array is derived from
calculating the modified far-field signature. The far-field signature
is often used as a theoretical representation of the source level. To
compute the far-field signature, the source level is estimated at a
large distance below the array (e.g., 9 km), and this level is back
projected mathematically to a notional distance of 1 m from the array's
geometrical center. However, it has been recognized that the source
level from the theoretical far-field signature is never physically
achieved at the source when the source is an array of multiple airguns
separated in space (Tolstoy et al., 2009). Near the source (at short
ranges, distances <1 km), the pulses of sound pressure from each
individual airgun in the source array do not stack constructively as
they do for the theoretical far-field signature. The pulses from the
different airguns spread out in time such that the source levels
observed or modeled are the result of the summation of pulses from a
few airguns, not the full array (Tolstoy et al., 2009). At larger
distances, away from the source array center, sound pressure of all the
airguns in the array stack coherently, but not within one time sample,
resulting in smaller source levels (a few dB) than the source level
derived from the far-field signature. Because the far-field signature
does not take into account the interactions of the two airguns that
occur near the source center and is calculated as a point source
(single airgun), the modified far-field signature is a more appropriate
measure of the sound source level for large arrays. For this smaller
array, the modified far-field changes will be correspondingly smaller
as well, but we use this method for consistency across all array sizes.
Scripps used the same acoustic modeling as for Level B harassment
with a small grid step in both the inline and depth directions to
estimate the SEL<INF>cum</INF> and peak SPL. The propagation modeling
takes into account all airgun interactions at short distances from the
source including interactions between subarrays using the NUCLEUS
software to estimate the notional signature and the MATLAB software to
calculate the pressure signal at each mesh point of a grid. For a more
complete explanation of this modeling approach, please see ``Appendix
A: Determination of Mitigation Zones'' in Scripps' IHA application.
In order to more realistically incorporate the Technical Guidance's
weighting functions over the seismic array's full acoustic band,
unweighted spectrum data for the airgun array (modeled in 1 Hertz (Hz)
bands) was used to make adjustments (dB) to the unweighted spectrum
levels, by frequency, according to the weighting functions for each
relevant marine mammal hearing group. These adjusted/weighted spectrum
levels were then converted to pressures ([mu]Pa) in order to integrate
them over the entire broadband spectrum, resulting in broadband
weighted source levels by hearing group that could be directly
incorporated within the User Spreadsheet (i.e., to override the
Spreadsheet's more simple weighting factor adjustment). Using the User
Spreadsheet's ``safe distance'' methodology for mobile sources
(described by Sivle et al., 2014) with the hearing group-specific
weighted source levels, and inputs assuming spherical spreading
propagation and source velocities and shot intervals provided in
Scripps' IHA application, potential radial distances to auditory injury
zones were calculated for PTS thresholds. Calculated Level A harassment
zones for all cetacean hearing groups are presented in Table 5 below
(no pinnipeds are expected to occur in the survey area).
Table 5--Modeled Radial Distances (m) to Isopleths Corresponding to
Level A Harassment Thresholds
------------------------------------------------------------------------
Level A
Functional hearing group harassment
zone (m)
------------------------------------------------------------------------
Low-frequency cetaceans \1\................................. 9.9
Mid-frequency cetaceans..................................... 1.0
High-frequency cetaceans.................................... 34.6
------------------------------------------------------------------------
\1\ Low-frequency cetaceans are not expected to be encountered or taken
by Level A or Level B harassment during the survey.
Note that because of some of the assumptions included in the
methods used, isopleths produced may be overestimates to some degree,
which will ultimately result in some degree of overestimate of the
potential for take by Level A harassment. However, these tools offer
the best way to predict appropriate isopleths when more sophisticated
3D modeling methods are not available, and NMFS continues to develop
ways to quantitatively refine these tools and will qualitatively
address the output where appropriate. For mobile sources, such as the
planned seismic survey, the User Spreadsheet predicts the closest
distance at which a stationary animal would not incur PTS if the sound
source traveled by the animal in a straight line at a constant speed.
Auditory injury is unlikely to occur for any functional hearing
group given the very small modeled zones of injury (all estimated zones
less than 35 meters (m)), and we therefore expect the potential for
Level A harassment to be de minimis, even before the likely moderating
effects of aversion and/or other compensatory behaviors (e.g.,
Nachtigall et al., 2018) are considered. Additionally, the method of
estimating take as described below (see Take Calculation and
Estimation) yielded only two species/guilds with calculated takes by
Level A harassment, and the highest calculated take of those two groups
was only two takes by Level A harassment (Table 9). We do not believe
that Level A harassment is a likely outcome for any hearing group and
have not authorized take by Level A harassment for any species.
Marine Mammal Occurrence
In this section we provide the information about the presence,
density, or group dynamics of marine mammals that will inform the take
calculations.
For the planned survey area in the southeast Gulf of Mexico,
Scripps determined that the best source of density data for marine
mammal species that might be encountered in the project area was
habitat-based density modeling conducted by Roberts et al. (2016). The
Roberts et al. (2016) data provide abundance estimates for species or
species guilds within 10 km x 10 km grid cells (100 square kilometer
(km\2\)) within the U.S. EEZ in the Gulf of Mexico and Atlantic Ocean
on a monthly or annual basis, depending on the species and location. In
the Gulf of Mexico, marine mammals do not migrate seasonally, so a
single estimate for each grid cell is provided and represents the
predicted abundance of that species in that 100 km\2\ location at any
time of year.
As the planned survey lines are outside of the U.S. EEZ, they do
not directly overlap the available spatial density data. However, some
of the survey lines occur near the U.S. EEZ, and the distribution and
abundance of species in U.S. EEZ waters are assumed representative of
those in the nearby survey area. To select a representative
[[Page 40193]]
sample of grid cells for the calculation of densities in three
different water depth categories (>100 m, 100-1,000 m, and >1,000 m), a
200-km perimeter around the survey lines was created in GIS. The areas
within this perimeter within the three depth categories was then used
to select grid cells containing the estimates for each species in the
Roberts et al. (2016) data (i.e., <100 m, n = 157 grid cells; 100-
1,000, n = 169 grid cells; >1,000 m, n = 410 grid cells). The average
abundance for each species in each water depth category was calculated
as the mean value of the grid cells within each category and then
converted to density (individuals/1 km\2\) by dividing by 100 km\2\.
Estimated densities for marine mammal species that could occur in the
project area are shown in Table 6.
Table 6--Marine Mammal Densities in the Survey Area
------------------------------------------------------------------------
Estimated density (#/km\2\)
-------------------------------
Species Intermediate
water 100- Deep water
1,000 m >1,000 m
------------------------------------------------------------------------
Sperm whale............................. 0.00384 0.00579
Atlantic spotted dolphin................ 0.07022 0.00001
Beaked whale guild \a\.................. 0.00498 0.00882
Common bottlenose dolphin............... 0.18043 0.00566
Clymene dolphin......................... 0.00325 0.00403
False killer whale...................... 0.00744 0.00748
Frasers dolphin......................... 0.00386 0.00389
Killer whale............................ 0.00007 0.00082
Melon-headed whale...................... 0.00624 0.01186
Pantropical spotted dolphin............. 0.14764 0.31353
Short-finned pilot whales............... 0.00636 0.00128
Pygmy killer whale...................... 0.00201 0.00648
Risso's dolphin......................... 0.02315 0.00748
Rough-toothed dolphin................... 0.00890 0.00768
Spinner dolphin......................... 0.15723 0.00412
Striped dolphin......................... 0.00212 0.01268
Kogia spp.\b\........................... 0.01052 0.00490
------------------------------------------------------------------------
\a\ Includes Cuvier's beaked whale, Blainville's beaked whale, and
Gervais' beaked whale.
\b\ Pygmy sperm whales and dwarf sperm whales.
Take Calculation and Estimation
Here we describe how the information provided above is brought
together to produce a quantitative take estimate.
The area expected to be ensonified was determined by entering the
planned survey lines into ArcGIS and then using GIS to identify the
relevant ensonified areas by ``drawing'' the 160-dB threshold buffer
around each seismic line according to the depth category in which the
lines occurred. The total ensonified area within each depth category
was then divided by the total number of survey days to provide the
proportional daily ensonified area within each depth category. The
total ensonified area in each depth class was multiplied by 1.25 to add
an additional 25 percent contingency to allow for additional airgun
operations such as testing of the source or re-surveying lines with
poor data quality. Due to uncertainties with respect to permitting for
surveys in Cuban waters, ensonified areas were calculated separately
for transect lines in Mexican and Cuban EEZs, for which 4.2 and 5.5
survey days were estimated, respectively (Table 7). If Scripps is
unable to operate within the Cuban EEZ, they will conduct the entire
survey within the Mexican EEZ, with the same estimated daily
proportions of survey activity in each depth strata occurring over a
total of 9.7 survey days. This scenario yields a total ensonified area
of 3,595.6 km\2\, with 1,848.6 km\2\ in intermediate waters (100-1,000
m) and 1,747.0 km\2\ in deep waters (>1,000 m).
Table 7--Areas (km\2\) in Mexican and Cuban EEZs to be Ensonified Above Level B Harassment Threshold
----------------------------------------------------------------------------------------------------------------
Ensonified Total area
Relevant area in Ensonified Total with 25%
Water depth category isopleth (m) Mexican EEZ area in Cuban ensonified increase
(km\2\) EEZ (km\2\) area (km\2\) (km\2\)
----------------------------------------------------------------------------------------------------------------
Intermediate (100-1000 m)....... 809 640.35 0 640.35 800.44
Deep (>1000).................... 539 605.14 1298.09 1903.23 2379.04
-------------------------------------------------------------------------------
Total....................... .............. 1245.49 1298.09 2543.58 3179.48
----------------------------------------------------------------------------------------------------------------
To estimate the total number of possible exposures, the total
ensonified area within each depth category is multiplied by the
densities in each depth category. Scripps does not expect to know
whether surveying within Cuban waters will be permitted until
immediately before the research cruise, therefore NMFS has authorized
the highest calculated take number for each species across the two
survey scenarios (Table 8).
[[Page 40194]]
Table 8--Calculated and Authorized Takes by Level B Harassment, and Percentage of Population Exposed
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Mexico and Mexico and
Cuba lines Cuba lines Mexico only Mexico only Authorized Authorized Population Percent of
Species calculated calculated calculated calculated level B level A size \a\ population
level B level A level B level A
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale..................................................... 17 0 17 0 17 0 2,207 0.78
Atlantic spotted dolphin........................................ 56 0 130 0 130 0 74,785 0.17
Beaked whale guild \c\.......................................... 25 0 25 0 25 0 3,768 0.66
Common bottlenose dolphin....................................... 158 0 343 0 343 0 176,108 0.20
Clymene dolphin................................................. \b\ 90 0 \b\ 90 0 \b\ 90 0 11,895 0.76
False killer whale.............................................. \b\ 28 0 \b\ 28 0 \b\ 28 0 3,204 0.87
Frasers dolphin................................................. \b\ 65 0 \b\ 65 0 \b\ 65 0 1,665 3.90
Killer whale.................................................... \b\ 7 0 \b\ 7 0 \b\ 7 0 267 2.62
Melon-headed whale.............................................. \b\ 100 0 \b\ 100 0 \b\ 100 0 7,003 1.43
Pantropical spotted dolphin..................................... 862 2 820 1 864 0 102,361 0.84
Pygmy killer whale.............................................. \b\ 19 0 \b\ 19 0 \b\ 19 0 2,126 0.89
Risso's dolphin................................................. 36 0 56 0 56 0 3,764 1.48
Rough-toothed dolphin........................................... \b\ 56 0 \b\ 56 0 \b\ 56 0 4,853 1.15
Short-finned pilot whales....................................... \b\ 25 0 \b\ 25 0 \b\ 25 0 1,981 1.26
Spinner dolphin................................................. 136 0 298 0 298 0 25,114 1.19
Striped dolphin................................................. \b\ 46 0 \b\ 46 0 \b\ 46 0 5,229 0.88
Kogia spp....................................................... 19 1 27 1 28 0 4,373 0.64
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Best abundance estimate. For most taxa, the best abundance estimate for purposes of comparison with take estimates is considered here to be the model-predicted abundance (Roberts et al.,
2016). For those taxa where a density surface model predicting abundance by month was produced, the maximum mean seasonal abundance was used. For those taxa where abundance is not predicted
by month, only mean annual abundance is available. For the killer whale, the larger estimated SAR abundance estimate is used.
\b\ Calculated and authorized take increased to mean group size as presented by Maze-Foley and Mullin (2006).
\c\ Cuvier's, Blainville's, and Gervais' beaked whales.
Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting the
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, we
carefully consider two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat.
This considers the nature of the potential adverse impact being
mitigated (likelihood, scope, range). It further considers the
likelihood that the measure will be effective if implemented
(probability of accomplishing the mitigating result if implemented as
planned), the likelihood of effective implementation (probability
implemented as planned); and
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost, impact on
operations, and, in the case of a military readiness activity,
personnel safety, practicality of implementation, and impact on the
effectiveness of the military readiness activity.
Scripps indicated that it reviewed mitigation measures employed
during seismic research surveys authorized by NMFS under previous
incidental harassment authorizations, as well as recommended best
practices in Richardson et al. (1995), Pierson et al. (1998), Weir and
Dolman (2007), Nowacek et al. (2013), Wright (2014), and Wright and
Cosentino (2015), and has incorporated a suite of mitigation measures
into their project description based on the above sources.
To reduce the potential for disturbance from acoustic stimuli
associated with the activities, Scripps will implement mitigation
measures for marine mammals. Mitigation measures that must be adopted
during the planned surveys include: (1) Vessel-based visual mitigation
monitoring; (2) Establishment of a marine mammal exclusion zone (EZ)
and buffer zone; (3) shutdown procedures; (4) ramp-up procedures; and
(4) vessel strike avoidance measures.
Vessel-Based Visual Mitigation Monitoring
Visual monitoring requires the use of trained observers (herein
referred to as visual Protected Species Observers (PSOs)) to scan the
ocean surface visually for the presence of marine mammals. PSO
observations must take place during all daytime airgun operations and
nighttime start ups (if applicable) of the airguns. If airguns are
operating throughout the night, observations must begin 30 minutes
prior to sunrise. If airguns are operating after sunset, observations
must continue until 30 minutes following sunset. Following a shutdown
for any reason, observations must occur for at least 30 minutes prior
to the planned start of airgun operations. Observations must also occur
for 30 minutes after airgun operations cease for any reason.
Observations must also be made during daytime periods when the R/V
Justo Sierra is underway without seismic operations, such as during
transits, to allow for comparison of sighting rates and behavior with
and without airgun operations and between acquisition periods. Airgun
operations must be suspended when marine mammals are observed within,
or about to enter, the designated exclusion zone (EZ) (as described
below).
During seismic operations, two visual PSOs must be on duty and
conduct visual observations at all times during daylight hours (i.e.,
from 30 minutes prior to sunrise through 30 minutes following sunset).
PSO(s) must be on duty in shifts of duration no longer than
[[Page 40195]]
4 hours. Other vessel crew must also be instructed to assist in
detecting marine mammals and in implementing mitigation requirements
(if practical). Before the start of the seismic survey, the crew must
be given additional instruction in detecting marine mammals and
implementing mitigation requirements.
The R/V Justo Sierra is a suitable platform from which PSOs would
watch for marine mammals. Standard equipment for marine mammal
observers must be 7 x 50 reticule binoculars and optical range finders.
At night, night-vision equipment must be available. The observers must
be in communication with ship's officers on the bridge and scientists
in the vessel's operations laboratory, so they can advise promptly of
the need for vessel strike avoidance measures (see Vessel Strike
Avoidance Measures below) or seismic source shutdown.
The PSOs must have no tasks other than to conduct observational
effort, record observational data, and communicate with and instruct
relevant vessel crew with regard to the presence of marine mammals and
mitigation requirements. PSO resumes must be provided to NMFS for
approval. At least one PSO must have a minimum of 90 days prior at-sea
experience working as a PSO during a seismic survey. One
``experienced'' visual PSO will be designated as the lead for the
entire protected species observation team. The lead will serve as
primary point of contact for the vessel operator.
Exclusion Zone (EZ) and Buffer Zone
An EZ is a defined area within which occurrence of a marine mammal
triggers mitigation action intended to reduce the potential for certain
outcomes, e.g., auditory injury, disruption of critical behaviors. The
PSOs must establish a minimum EZ with a 100 m radius for the airgun
array. The 100-m EZ must be based on radial distance from any element
of the airgun array (rather than being based around the vessel itself).
With certain exceptions (described below), if a marine mammal appears
within, enters, or appears on a course to enter this zone, the acoustic
source must be shut down (see Shutdown Procedures below).
The 100-m radial distance of the standard EZ is precautionary in
the sense that it would be expected to contain sound exceeding injury
criteria for all marine mammal hearing groups (Table 5) while also
providing a consistent, reasonably observable zone within which PSOs
would typically be able to conduct effective observational effort. In
the 2011 Programmatic Environmental Impact Statement for marine
scientific research funded by the National Science Foundation or the
U.S. Geological Survey (NSF-USGS 2011), Alternative B (the Preferred
Alternative) conservatively applied a 100-m EZ for all low-energy
acoustic sources in water depths >100 m, with low-energy acoustic
sources defined as any towed acoustic source with a single or a pair of
clustered airguns with individual volumes of <=250 in\3\. Thus the 100-
m EZ required for this survey is consistent with the PEIS.
Our intent in prescribing a standard EZ distance is to (1)
encompass zones within which auditory injury could occur on the basis
of instantaneous exposure; (2) provide additional protection from the
potential for more severe behavioral reactions (e.g., panic,
antipredator response) for marine mammals at relatively close range to
the acoustic source; (3) provide consistency for PSOs, who need to
monitor and implement the EZ; and (4) define a distance within which
detection probabilities are reasonably high for most species under
typical conditions.
PSOs must also establish and monitor a 100-m buffer zone beyond the
EZ (for a total of 200 m). During use of the acoustic source,
occurrence of marine mammals within the buffer zone (but outside the
EZ) must be communicated to the operator to prepare for potential
shutdown of the acoustic source. The buffer zone is discussed further
under Ramp-Up Procedures below.
An extended EZ of 500 m must be established for all beaked whales
and Kogia species as well as for aggregations of six or more large
whales (i.e., sperm whale) or a large whale with a calf (calf defined
as an animal less than two-thirds the body size of an adult observed to
be in close association with an adult).
Ramp-Up Procedures
Ramp-up of an acoustic source is intended to provide a gradual
increase in sound levels following a shutdown, enabling animals to move
away from the source if the signal is sufficiently aversive prior to
its reaching full intensity. Ramp-up is required after the array is
shut down for any reason for longer than 15 minutes. Ramp-up must begin
with the activation of one 45 in\3\ airgun, with the second 45 in\3\
airgun activated after 5 minutes.
Two PSOs are required to monitor during ramp-up. During ramp up,
the PSOs must monitor the EZ, and if marine mammals were observed
within the EZ or buffer zone, a shutdown must be implemented as though
the full array were operational. If airguns have been shut down due to
PSO detection of a marine mammal within or approaching the EZ, ramp-up
must not be initiated until all marine mammals have cleared the EZ,
during the day or night. Criteria for clearing the EZ would be as
described above.
Thirty minutes of pre-start clearance observation are required
prior to ramp-up for any shutdown of longer than 30 minutes (i.e., when
the array is shut down during transit from one line to another). This
30-minute pre-start clearance period may occur during any vessel
activity (i.e., transit). If a marine mammal is observed within or
approaching the 200-m buffer or 500-m extended EZ during this pre-start
clearance period, ramp-up must not be initiated until all marine
mammals cleared the relevant area. Criteria for clearing the EZ would
be as described above. If the airgun array has been shut down for
reasons other than mitigation (e.g., mechanical difficulty) for a
period of less than 30 minutes, it may be activated again without ramp-
up if PSOs have maintained constant visual observation and no
detections of any marine mammal have occurred within the EZ or buffer
zone. Ramp-up must be planned to occur during periods of good
visibility when possible. However, ramp-up is allowed at night and
during poor visibility if the 100 m EZ and 200 m buffer zone have been
monitored by visual PSOs for 30 minutes prior to ramp-up.
The operator is required to notify a designated PSO of the planned
start of ramp-up as agreed-upon with the lead PSO; the notification
time must not be less than 60 minutes prior to the planned ramp-up. A
designated PSO must be notified again immediately prior to initiating
ramp-up procedures and the operator must receive confirmation from the
PSO to proceed. The operator must provide information to PSOs
documenting that appropriate procedures were followed. Following
deactivation of the array for reasons other than mitigation, the
operator is required to communicate the near-term operational plan to
the lead PSO with justification for any planned nighttime ramp-up.
Shutdown Procedures
If a marine mammal is detected outside the EZ but is likely to
enter the EZ, the airguns must be shut down before the animal is within
the EZ. Likewise, if a marine mammal is already within the EZ when
first detected, the airguns must be shut down immediately.
Following a shutdown, airgun activity must not resume until the
marine mammal has cleared the EZ. The animal
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is considered to have cleared the EZ if the following conditions have
been met:
<bullet> it is visually observed to have departed the EZ;
<bullet> it has not been seen within the EZ for 15 min in the case
of small odontocetes; or
<bullet> it has not been seen within the EZ for 30 min in the case
of large odontocetes, including sperm and beaked whales.
This shutdown requirement is in place for all marine mammals, with
the exception of small delphinids under certain circumstances. As
defined here, the small delphinid group is intended to encompass those
members of the Family Delphinidae most likely to voluntarily approach
the source vessel for purposes of interacting with the vessel and/or
airgun array (e.g., bow riding). This exception to the shutdown
requirement would apply solely to specific genera of small dolphins--
Lagenodelphis, Stenella, Steno, and Tursiops.
We include this small delphinid exception because shutdown
requirements for small delphinids under all circumstances represent
practicability concerns without likely commensurate benefits for the
animals in question. Small delphinids are generally the most commonly
observed marine mammals in the specific geographic region and would
typically be the only marine mammals likely to intentionally approach
the vessel. As described above, auditory injury is extremely unlikely
to occur for mid-frequency cetaceans (e.g., delphinids), as this group
is relatively insensitive to sound produced at the predominant
frequencies in an airgun pulse while also having a relatively high
threshold for the onset of auditory injury (i.e., permanent threshold
shift).
A large body of anecdotal evidence indicates that small delphinids
commonly approach vessels and/or towed arrays during active sound
production for purposes of bow riding, with no apparent effect observed
in those delphinids (e.g., Barkaszi et al., 2012, 2018). The potential
for increased shutdowns resulting from such a measure would require the
R/V Justo Sierra to revisit the missed track line to reacquire data,
resulting in an overall increase in the total sound energy input to the
marine environment and an increase in the total duration over which the
survey is active in a given area. Although other mid-frequency hearing
specialists (e.g., large delphinids) are no more likely to incur
auditory injury than are small delphinids, they are much less likely to
approach vessels. Therefore, retaining a shutdown requirement for large
delphinids would not have similar impacts in terms of either
practicability for the applicant or corollary increase in sound energy
output and time on the water. We do anticipate some benefit for a
shutdown requirement for large delphinids in that it simplifies
somewhat the total range of decision-making for PSOs and may preclude
any potential for physiological effects other than to the auditory
system as well as some more severe behavioral reactions for any such
animals in close proximity to the source vessel.
Visual PSOs must use best professional judgment in making the
decision to call for a shutdown if there is uncertainty regarding
identification (i.e., whether the observed marine mammal(s) belongs to
one of the delphinid genera for which shutdown is waived or one of the
species with a larger EZ).
Shutdown of the acoustic source is also required upon observation
of a species for which authorization has not been granted (e.g., baleen
whales), or a species for which authorization has been granted but the
authorized number of takes are met, observed approaching or within the
Level B harassment zones.
Vessel Strike Avoidance Measures
Vessel strike avoidance measures are intended to minimize the
potential for collisions with marine mammals. These requirements do not
apply in any case where compliance would create an imminent and serious
threat to a person or vessel or to the extent that a vessel is
restricted in its ability to maneuver and, because of the restriction,
cannot comply.
The required measures include the following: Vessel operator and
crew must maintain a vigilant watch for all marine mammals and slow
down or stop the vessel or alter course to avoid striking any marine
mammal. A visual observer aboard the vessel must monitor a vessel
strike avoidance zone around the vessel according to the parameters
stated below. Visual observers monitoring the vessel strike avoidance
zone may be either third-party observers or crew members, but crew
members responsible for these duties must be provided sufficient
training to distinguish marine mammals from other phenomena. Vessel
strike avoidance measures must be followed during surveys and while in
transit.
The vessel must maintain a minimum separation distance of 100 m
from large whales (i.e., baleen whales and sperm whales). If a large
whale is within 100 m of the vessel, the vessel must reduce speed and
shift the engine to neutral, and must not engage the engines until the
whale has moved outside of the vessel's path and the minimum separation
distance has been established. If the vessel is stationary, the vessel
must not engage engines until the whale(s) has moved out of the
vessel's path and beyond 100 m. The vessel must maintain a minimum
separation distance of 50 m from all other marine mammals, to the
extent practicable. If an animal is encountered during transit, the
vessel must attempt to remain parallel to the animal's course, avoiding
excessive speed or abrupt changes in course. Vessel speeds must be
reduced to 10 knots or less when mother/calf pairs, pods, or large
assemblages of cetaceans are observed near the vessel.
We have carefully evaluated the suite of mitigation measures
described here and considered a range of other measures in the context
of ensuring that we prescribe the means of effecting the least
practicable adverse impact on the affected marine mammal species and
stocks and their habitat. Based on our evaluation of the required
measures, NMFS has determined that the mitigation measures provide the
means effecting the least practicable impact on the affected species or
stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance.
Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104 (a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present in the
planned survey area. Effective reporting is critical both to compliance
as well as ensuring that the most value is obtained from the required
monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density).
<bullet> Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through
[[Page 40197]]
better understanding of: (1) action or environment (e.g., source
characterization, propagation, ambient noise); (2) affected species
(e.g., life history, dive patterns); (3) co-occurrence of marine mammal
species with the action; or (4) biological or behavioral context of
exposure (e.g., age, calving or feeding areas).
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors.
<bullet> How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks.
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat).
<bullet> Mitigation and monitoring effectiveness.
Monitoring that is designed specifically to facilitate mitigation
measures, such as monitoring of the EZ to inform potential shutdowns of
the airgun array, are described above and are not repeated here. The
required monitoring and reporting includes the following:
Vessel-Based Visual Monitoring
As described above, PSO observations must take place during daytime
airgun operations and nighttime start-ups (if applicable) of the
airguns. During seismic operations, visual PSOs must be based aboard
the R/V Justo Sierra. PSOs must be appointed by Scripps with NMFS
approval. The PSOs must have successfully completed relevant training,
including completion of all required coursework and passing a written
and/or oral examination developed for the training program, and must
have successfully attained a bachelor's degree from an accredited
college or university with a major in one of the natural sciences and a
minimum of 30 semester hours or equivalent in the biological sciences
and at least one undergraduate course in math or statistics. The
educational requirements may be waived if the PSO has acquired the
relevant skills through alternate training, including (1) secondary
education and/or experience comparable to PSO duties; (2) previous work
experience conducting academic, commercial, or government-sponsored
marine mammal surveys; or (3) previous work experience as a PSO; the
PSO must demonstrate good standing and consistently good performance of
PSO duties.
During seismic operations in daylight hours (30 minutes before
sunrise through 30 minutes after sunset), two PSOs must monitor for
marine mammals around the seismic vessel. PSOs must be on duty in
shifts of duration no longer than 4 hours. Other crew must also be
instructed to assist in detecting marine mammals and in implementing
mitigation requirements (if practical). During daytime, PSOs must scan
the area around the vessel systematically with reticle binoculars
(e.g., 7 x 50 Fujinon) and with the naked eye. At night, PSOs must be
equipped with night-vision equipment.
For data collection purposes, PSOs must use standardized data
collection forms, whether hard copy or electronic. PSOs must record
detailed information about any implementation of mitigation
requirements, including the distance of animals to the acoustic source
and description of specific actions that ensued, the behavior of the
animal(s), any observed changes in behavior before and after
implementation of mitigation, and if shutdown was implemented, the
length of time before any subsequent ramp-up of the acoustic source. If
required mitigation was not implemented, PSOs must record a description
of the circumstances. At a minimum, the following information must be
recorded:
<bullet> Vessel names (source vessel and other vessels associated
with survey) and call signs;
<bullet> PSO names and affiliations;
<bullet> Dates of departures and returns to port with port name;
<bullet> Date and participants of PSO briefings;
<bullet> Dates and times (Greenwich Mean Time) of survey effort and
times corresponding with PSO effort;
<bullet> Vessel location (latitude/longitude) when survey effort
began and ended and vessel location at beginning and end of visual PSO
duty shifts;
<bullet> Vessel heading and speed at beginning and end of visual
PSO duty shifts and upon any line change;
<bullet> Environmental conditions while on visual survey (at
beginning and end of PSO shift and whenever conditions changed
significantly), including BSS and any other relevant weather conditions
including cloud cover, fog, sun glare, and overall visibility to the
horizon;
<bullet> Factors that may have contributed to impaired observations
during each PSO shift change or as needed as environmental conditions
changed (e.g., vessel traffic, equipment malfunctions); and
<bullet> Survey activity information, such as acoustic source power
output while in operation, number and volume of airguns operating in
the array, tow depth of the array, and any other notes of significance
(i.e., pre-clearance, ramp-up, shutdown, testing, shooting, ramp-up
completion, end of operations, streamers, etc.).
The following information must be recorded upon visual observation
of any protected species:
<bullet> Watch status (sighting made by PSO on/off effort,
opportunistic, crew, alternate vessel/platform);
<bullet> PSO who sighted the animal;
<bullet> Time of sighting;
<bullet> Vessel location at time of sighting;
<bullet> Water depth;
<bullet> Direction of vessel's travel (compass direction);
<bullet> Direction of animal's travel relative to the vessel;
<bullet> Pace of the animal;
<bullet> Estimated distance to the animal and its heading relative
to vessel at initial sighting;
<bullet> Identification of the animal (e.g., genus/species, lowest
possible taxonomic level, or unidentified) and the composition of the
group if there is a mix of species;
<bullet> Estimated number of animals (high/low/best);
<bullet> Estimated number of animals by cohort (adults, yearlings,
juveniles, calves, group composition, etc.);
<bullet> Description (as many distinguishing features as possible
of each individual seen, including length, shape, color, pattern, scars
or markings, shape and size of dorsal fin, shape of head, and blow
characteristics);
<bullet> Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding,
traveling; as explicit and detailed as possible; note any observed
changes in behavior);
<bullet> Animal's closest point of approach (CPA) and/or closest
distance from any element of the acoustic source;
<bullet> Platform activity at time of sighting (e.g., deploying,
recovering, testing, shooting, data acquisition, other); and
<bullet> Description of any actions implemented in response to the
sighting (e.g., delays, shutdown, ramp-up) and time and location of the
action.
Reporting
A report must be submitted to NMFS within 90 days after the end of
the cruise. The report must describe the operations that were conducted
and sightings of marine mammals near the operations. The report must
provide full documentation of methods, results, and interpretation
pertaining to all
[[Page 40198]]
monitoring. The 90-day report must summarize the dates and locations of
seismic operations, and all marine mammal sightings (dates, times,
locations, activities, associated seismic survey activities).
The draft report must also include geo-referenced time-stamped
vessel tracklines for all time periods during which airguns were
operating. Tracklines must include points recording any change in
airgun status (e.g., when the airguns began operating, when they were
turned off, or when they changed from full array to single gun or vice
versa). GIS files must be provided in ESRI shapefile format and include
the UTC date and time, latitude in decimal degrees, and longitude in
decimal degrees. All coordinates must be referenced to the WGS84
geographic coordinate system. In addition to the report, all raw
observational data must be made available to NMFS. The report must
summarize the data collected as described above and in the IHA. A final
report must be submitted within 30 days following resolution of any
comments on the draft report.
Reporting Injured or Dead Marine Mammals
Discovery of injured or dead marine mammals--In the event that
personnel involved in survey activities covered by the authorization
discover an injured or dead marine mammal, Scripps must report the
incident to the Office of Protected Resources (OPR), NMFS and to the
NMFS Southeast Regional Stranding Coordinator as soon as feasible. The
report must include the following information:
<bullet> Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Condition of the animal(s) (including carcass condition if
the animal is dead);
<bullet> Observed behaviors of the animal(s), if alive;
<bullet> If available, photographs or video footage of the
animal(s); and
<bullet> General circumstances under which the animal was
discovered.
Vessel strike--In the event of a ship strike of a marine mammal by
any vessel involved in the activities covered by the authorization,
Scripps must report the incident to OPR, NMFS and to the NMFS Southeast
Regional Stranding Coordinator as soon as feasible. The report must
include the following information:
<bullet> Time, date, and location (latitude/longitude) of the
incident;
<bullet> Vessel's speed during and leading up to the incident;
<bullet> Vessel's course/heading and what operations were being
conducted (if applicable);
<bullet> Status of all sound sources in use;
<bullet> Description of avoidance measures/requirements that were
in place at the time of the strike and what additional measure were
taken, if any, to avoid strike;
<bullet> Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, visibility) immediately preceding the
strike;
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Estimated size and length of the animal that was struck;
<bullet> Description of the behavior of the animal immediately
preceding and following the strike;
<bullet> If available, description of the presence and behavior of
any other marine mammals present immediately preceding the strike;
<bullet> Estimated fate of the animal (e.g., dead, injured but
alive, injured and moving, blood or tissue observed in the water,
status unknown, disappeared); and
<bullet> To the extent practicable, photographs or video footage of
the animal(s).
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any responses (e.g., intensity, duration), the context
of any responses (e.g., critical reproductive time or location,
migration), as well as effects on habitat, and the likely effectiveness
of the mitigation. We also assess the number, intensity, and context of
estimated takes by evaluating this information relative to population
status. Consistent with the 1989 preamble for NMFS's implementing
regulations (54 FR 40338; September 29, 1989), the impacts from other
past and ongoing anthropogenic activities are incorporated into this
analysis via their impacts on the environmental baseline (e.g., as
reflected in the regulatory status of the species, population size and
growth rate where known, ongoing sources of human-caused mortality, or
ambient noise levels).
To avoid repetition, our analysis applies to all species listed in
Table 1, given that NMFS expects the anticipated effects of the planned
geophysical survey to be similar in nature. Where there are meaningful
differences between species or stocks, or groups of species, in
anticipated individual responses to activities, impact of expected take
on the population due to differences in population status, or impacts
on habitat, NMFS has identified species-specific factors to inform the
analysis.
NMFS does not anticipate that injury, serious injury or mortality
would occur as a result of Scripps' planned survey, even in the absence
of mitigation, and none is authorized. Similarly, non-auditory physical
effects, stranding, and vessel strike are not expected to occur.
Although a few incidents of Level A harassment were predicted through
the quantitative exposure estimation process (see Estimated Take), NMFS
has determined that this is not a realistic result due to the small
estimated Level A harassment zones for the species (no greater than
approximately 50 m) and the mitigation requirements, and no take by
Level A harassment has been authorized. These estimated zones are
larger than what would realistically occur, as discussed in the
Estimated Take section.
We expect that takes would be in the form of short-term Level B
behavioral harassment in the form of temporary avoidance of the area or
decreased foraging (if such activity were occurring), reactions that
are considered to be of low severity and with no lasting biological
consequences (e.g., Southall et al., 2007, Ellison et al., 2012).
Marine mammal habitat may be impacted by elevated sound levels, but
these impacts would be temporary. Prey species are mobile and are
broadly distributed throughout the project area; therefore, marine
mammals that may be temporarily displaced during survey activities are
expected to be able to resume foraging once they have moved away from
areas with disturbing levels of underwater noise. Because of the
relatively short duration (up to 12 days) and temporary nature of the
disturbance, the availability of similar habitat and resources in the
surrounding area, the impacts to marine mammals and the food sources
that they utilize
[[Page 40199]]
are not expected to cause significant or long-term consequences for
individual marine mammals or their populations. No biologically
important areas, designated critical habitat, or other habitat of known
significance would be impacted by the planned activities.
Negligible Impact Conclusions
The planned survey would be of short duration (up to 12 days of
seismic operations), and the acoustic ``footprint'' of the survey would
be small relative to the ranges of the marine mammals that would
potentially be affected. Sound levels would increase in the marine
environment in a relatively small area surrounding the vessel compared
to the range of the marine mammals within the survey area. Short-term
exposures to survey operations are expected to only temporarily affect
marine mammal behavior in the form of avoidance, and the potential for
longer-term avoidance of important areas is limited. Short-term
exposures to survey operations are not likely to impact marine mammal
behavior, and the potential for longer-term avoidance of important
areas is limited.
The required mitigation measures are expected to reduce the number
and/or severity of takes by allowing for detection of marine mammals in
the vicinity of the vessel by visual observers, and by minimizing the
severity of any potential exposures via shutdowns of the airgun array.
NMFS concludes that exposures to marine mammal species and stocks
due to Scripps' planned survey would result in only short-term
(temporary and short in duration) effects to individuals exposed, over
relatively small areas of the affected animals' ranges. Animals may
temporarily avoid the immediate area, but are not expected to
permanently abandon the area. Major shifts in habitat use,
distribution, or foraging success are not expected. NMFS does not
anticipate the authorized take to impact annual rates of recruitment or
survival.
In summary and as described above, the following factors primarily
support our determination that the impacts resulting from this activity
are not expected to adversely affect the species or stock through
effects on annual rates of recruitment or survival:
<bullet> No Level A harassment, serious injury or mortality is
anticipated or authorized;
<bullet> The planned activity is temporary and of relatively short
duration (up to 12 days);
<bullet> The anticipated impacts of the planned activity on marine
mammals would primarily be temporary behavioral changes in the form of
avoidance of the area around the survey vessel;
<bullet> The availability of alternate areas of similar habitat
value for marine mammals to temporarily vacate the survey area during
the planned survey to avoid exposure to sounds from the activity;
<bullet> The potential adverse effects on fish or invertebrate
species that serve as prey species for marine mammals from the planned
survey would be temporary and spatially limited, and impacts to marine
mammal foraging would be minimal; and
<bullet> The required mitigation measures, including visual
monitoring, shutdowns, ramp-up, and prescribed measures based on energy
size are expected to minimize potential impacts to marine mammals (both
amount and severity).
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the required monitoring and
mitigation measures, NMFS finds that the total marine mammal take from
Scripps' activity will have a negligible impact on all affected marine
mammal species or stocks.
Small Numbers
As noted above, only small numbers of incidental take may be
authorized under sections 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. When the predicted number of
individuals to be taken is fewer than one third of the species or stock
abundance, the take is considered to be of small numbers. Additionally,
other qualitative factors may be considered in the analysis, such as
the temporal or spatial scale of the activities.
The amount of take NMFS has authorized is below one third of the
estimated population abundance of all species (Roberts et al., 2016).
In fact, take of individuals is less than 4 percent of the abundance of
the affected populations (see Table 8).
Based on the analysis contained herein of the planned activity
(including the required mitigation and monitoring measures) and the
anticipated take of marine mammals, NMFS finds that small numbers of
marine mammals will be taken relative to the population size of the
affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an
incidental harassment authorization) with respect to potential impacts
on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (incidental harassment authorizations with
no anticipated serious injury or mortality) of the Companion Manual for
NOAA Administrative Order 216-6A, which do not individually or
cumulatively have the potential for significant impacts on the quality
of the human environment and for which we have not identified any
extraordinary circumstances that would preclude this categorical
exclusion. Accordingly, NMFS has determined that the issuance of the
IHA qualifies to be categorically excluded from further NEPA review.
Endangered Species Act
Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16
U.S.C. 1531 et seq.) requires that each Federal agency insure that any
action it authorizes, funds, or carries out is not likely to jeopardize
the continued existence of any endangered or threatened species or
result in the destruction or adverse modification of designated
critical habitat. To ensure ESA compliance for the issuance of IHAs,
NMFS consults internally whenever we propose to authorize take for
endangered or threatened species, in this case with the ESA Interagency
Cooperation Division.
The NMFS Office of Protected Resources Interagency Cooperation
Division issued a Biological Opinion under section 7 of the ESA, on the
issuance of an IHA to Scripps under section 101(a)(5)(D) of the MMPA by
the NMFS Office of Protected Resources
[[Page 40200]]
Permits and Conservation Division. The Biological Opinion concluded
that the proposed action is not likely to jeopardize the continued
existence of any listed marine mammal species.
Authorization
As a result of these determinations, NMFS has issued an IHA to
Scripps for conducting geophysical surveys in the southeast Gulf of
Mexico in summer 2022, provided the previously mentioned mitigation,
monitoring, and reporting requirements are incorporated.
Dated: June 30, 2022.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2022-14362 Filed 7-5-22; 8:45 am]
BILLING CODE 3510-22-P
</pre></body>
</html>Indexed from Federal Register on July 6, 2022.
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