[Federal Register Volume 88, Number 203 (Monday, October 23, 2023)]
[Notices]
[Pages 72739-72743]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-23298]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD468]


Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to Geophysical Surveys Related to Oil and Gas Activities in 
the Gulf of Mexico

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

ACTION: Notice. Issuance of letter of authorization.

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SUMMARY: In accordance with the Marine Mammal Protection Act (MMPA), as 
amended, its implementing regulations, and NMFS' MMPA Regulations for 
Taking Marine Mammals Incidental to Geophysical Surveys Related to Oil 
and Gas Activities in the Gulf of Mexico, notification is hereby given 
that a Letter of Authorization (LOA) has been issued to WesternGeco for 
the take of marine mammals incidental to geophysical survey activity in 
the Gulf of Mexico.

DATES: The LOA is effective from October 17, 2023 through April 30, 
2024.

ADDRESSES: The LOA, LOA request, and supporting documentation are 
available online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico. In case of problems accessing these documents, please call 
the contact listed below (see FOR FURTHER INFORMATION CONTACT).

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

SUPPLEMENTARY INFORMATION: 

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce 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 issued or, if the taking 
is limited to harassment, a notice of a proposed authorization is 
provided to the public for review.
    An authorization for incidental takings shall be granted if NMFS 
finds that the taking will have a negligible impact on the species or 
stock(s), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant), and if the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such takings 
are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103 
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.
    Except with respect to certain activities not pertinent here, 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).
    On January 19, 2021, we issued a final rule with regulations to 
govern the unintentional taking of marine mammals incidental to 
geophysical survey activities conducted by oil and gas industry 
operators, and those persons authorized to conduct activities on their 
behalf (collectively ``industry operators''), in U.S. waters of the 
Gulf of Mexico (GOM) over the course of 5 years (86 FR 5322, January 
19, 2021). The rule was based on our findings that the total taking 
from the specified activities over the 5-year period will have a 
negligible impact on the affected species or stock(s) of marine mammals 
and will not have an unmitigable adverse impact on the availability of 
those species or stocks for subsistence uses. The rule became effective 
on April 19, 2021.
    Our regulations at 50 CFR 217.180 et seq. allow for the issuance of 
LOAs to industry operators for the incidental take of marine mammals 
during geophysical survey activities and prescribe the permissible 
methods of taking and other means of effecting the least practicable 
adverse impact on marine mammal species or stocks and their habitat 
(often referred to as mitigation), as well as requirements pertaining 
to the monitoring and reporting of such taking. Under Sec.  217.186 
(e), issuance of an LOA shall be based on a determination that the 
level of taking will be consistent with the findings made for the total 
taking allowable under these regulations and a determination that the 
amount of take

[[Page 72740]]

authorized under the LOA is of no more than small numbers.

Summary of Request and Analysis

    WesternGeco plans to conduct a three-dimensional (3D) ocean bottom 
node (OBN) survey in the Green Canyon and Walker Ridge protraction 
areas, including approximately 795 lease blocks. Approximate water 
depths of the survey area range from 1,000 to 3,000 meters (m). See 
section F of the LOA application for a map of the area.
    WesternGeco anticipates using two source vessels, towing low-
frequency airgun sources known as Gemini (also referred to as a dual 
barbell source) or conventional airgun sources consisting of 28 
elements, with a total volume of 5,240 cubic inches (in\3\). Please see 
WesternGeco's application for additional detail.
    The Gemini source was not included in the acoustic exposure 
modeling developed in support of the rule. However, our rule 
anticipated the possibility of new and unusual technologies (NUT) and 
determined they would be evaluated on a case-by case basis (86 FR 5322, 
5442, January 19, 2021). This source was previously evaluated as a NUT 
in 2020 (prior to issuance of the 2021 final rule) pursuant to the 
requirements of NMFS' 2020 Biological Opinion on BOEM's Gulf of Mexico 
oil and gas program as well as the issuance of the rule. An associated 
report produced by Jasco Applied Sciences (Grooms et al., 2019) 
provides information related to the acoustic output of the Gemini 
source, which informs our evaluation here.
    The Gemini source operates on the same basic principles as a 
traditional airgun source in that it uses compressed air to create a 
bubble in the water column which then goes through a series of 
collapses and expansions creating primarily low-frequency sounds. 
However, the Gemini source consists of one physical element with two 
large chambers of 4,000 (in\3\) each (total volume of 8,000 in\3\). 
This creates a larger bubble resulting in more of the energy being 
concentrated in low frequencies, with a fundamental frequency of 3.7 
Hertz. In addition to concentrating energy at lower frequencies, the 
Gemini source is expected to produce lower overall sound levels than 
the conventional airgun proxy source. The number of airguns in an array 
is highly influential on overall sound energy output, because the 
output increases approximately linearly with the number of airgun 
elements. In this case, because the same air volume is used to operate 
two very large guns, rather than tens of smaller guns, the array 
produces lower sound levels than a conventional array of equivalent 
total volume.
    The modeled distances described in the aforementioned Jasco report 
show expected per-pulse sound pressure level threshold distances to the 
160-dB level of 4.29 kilometers (km). When frequency-weighted, i.e., 
considering the low frequency output of the source relative to the 
hearing sensitivities of different marine mammal hearing groups, the 
estimated distance is decreased to approximately 1 km for the low-
frequency cetacean hearing group and to de minimis levels for mid- and 
high-frequency cetacean hearing groups, significantly less than 
comparable modeled distances for the proxy 72-element, 8,000 in\3\ 
array evaluated in the rule.
    These factors lead to a conclusion that take by Level B harassment 
associated with use of the Gemini source would be less than would occur 
for a similar survey instead using the modeled airgun array as a sound 
source. Based on the foregoing, we have determined there will be no 
effects of a magnitude or intensity different from those evaluated in 
support of the rule. Moreover, use of modeling results relating to use 
of the 72 element, 8,000 in\3\ airgun array are expected to be 
significantly conservative as a proxy for use in evaluating potential 
impacts of use of the Gemini source.
    Consistent with the preamble to the final rule, the survey effort 
proposed by WesternGeco in its LOA request was used to develop LOA-
specific take estimates based on the acoustic exposure modeling results 
described in the preamble (86 FR 5398, January 19, 2021). In order to 
generate the appropriate take numbers for authorization, the following 
information was considered: (1) survey type; (2) location (by modeling 
zone \1\); (3) number of days; and (4) season.\2\ The acoustic exposure 
modeling performed in support of the rule provides 24-hour exposure 
estimates for each species, specific to each modeled survey type in 
each zone and season.
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    \1\ For purposes of acoustic exposure modeling, the GOM was 
divided into seven zones. Zone 1 is not included in the geographic 
scope of the rule.
    \2\ For purposes of acoustic exposure modeling, seasons include 
winter (December-March) and summer (April-November).
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    No 3D OBN surveys were included in the modeled survey types, and 
use of existing proxies (i.e., two-dimensional (2D), 3D narrow-azimuth 
(NAZ), 3D wide-azimuth (WAZ), Coil) is generally conservative for use 
in evaluation of 3D OBN survey effort, largely due to the greater area 
covered by the modeled proxies. Summary descriptions of these modeled 
survey geometries are available in the preamble to the proposed rule 
(83 FR 29220, June 22, 2018). Coil was selected as the best available 
proxy survey type in this case because the spatial coverage of the 
planned survey is most similar to the coil survey pattern.
    The planned 3D OBN survey will involve two source vessels sailing 
along survey lines averaging 83 km in length. The coil survey pattern 
was assumed to cover approximately 144 kilometers squared (km\2\) per 
day (compared with approximately 795 km\2\, 199 km\2\, and 845 km\2\ 
per day for the 2D, 3D NAZ, and 3D WAZ survey patterns, respectively). 
Among the different parameters of the modeled survey patterns (e.g., 
area covered, line spacing, number of sources, shot interval, total 
simulated pulses), NMFS considers area covered per day to be most 
influential on daily modeled exposures exceeding Level B harassment 
criteria. Although WesternGeco is not proposing to perform a survey 
using the coil geometry, its planned 3D OBN survey is expected to cover 
approximately 99.6 km\2\ per day, meaning that the coil proxy is most 
representative of the effort planned by WesternGeco in terms of 
predicted Level B harassment exposures. In addition, all available 
acoustic exposure modeling results assume use of a 72-element, 8,000 
in\3\ array. Thus, as discussed above, estimated take numbers for this 
LOA are considered conservative due to differences between the acoustic 
source planned for use (Gemini or 28 element, 5,240 in\3\ airgun array) 
and the proxy array modeled for the rule.
    The survey will take place over approximately 85 days, including 65 
days of sound source operation. The survey plan includes approximately 
half the days within Zone 5 and half the days within Zone 7. We modeled 
33 days in each zone for take estimates. The seasonal distribution of 
survey days is not known in advance. Therefore, the take estimates for 
each species are based on the season that produces the greater value.
    For some species, take estimates based solely on the modeling 
yielded results that are not realistically likely to occur when 
considered in light of other relevant information available during the 
rulemaking process regarding marine mammal occurrence in the GOM. The 
approach used in the acoustic exposure modeling, in which seven 
modeling zones were defined over the U.S. GOM, necessarily averages 
fine-scale information about marine mammal distribution over the large 
area of each

[[Page 72741]]

modeling zone. This can result in unrealistic projections regarding the 
likelihood of encountering particularly rare species and/or species not 
expected to occur outside particular habitats. Thus, although the 
modeling conducted for the rule is a natural starting point for 
estimating take, our rule acknowledged that other information could be 
considered (e.g., 86 FR 5322, January 19, 2021), discussing the need to 
provide flexibility and make efficient use of previous public and 
agency review of other information and identifying that additional 
public review is not necessary unless the model or inputs used differ 
substantively from those that were previously reviewed by NMFS and the 
public). For this survey, NMFS has other relevant information reviewed 
during the rulemaking that indicates use of the acoustic exposure 
modeling to generate a take estimate for Rice's whales and killer 
whales produces results inconsistent with what is known regarding their 
occurrence in the GOM. Accordingly, we have adjusted the calculated 
take estimates for those species as described below.
    NMFS' final rule described a ``core habitat area'' for Rice's 
whales (formerly known as GOM Bryde's whales) \3\ located in the 
northeastern GOM in waters between 100 and 400 m depth along the 
continental shelf break (Rosel et al., 2016). However, whaling records 
suggest that Rice's whales historically had a broader distribution 
within similar habitat parameters throughout the GOM (Reeves et al., 
2011; Rosel and Wilcox, 2014). In addition, habitat-based density 
modeling identified similar habitat (i.e., approximately 100-400 m 
water depths along the continental shelf break) as being potential 
Rice's whale habitat (Roberts et al., 2016), although the core habitat 
area contained approximately 92 percent of the predicted abundance of 
Rice's whales. See discussion provided at, e.g., 83 FR 29228, June 22, 
2018; 83 FR 29280, June 22, 2018; 86 FR 5418, January 19, 2021.
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    \3\ The final rule refers to the GOM Bryde's whale (Balaenoptera 
edeni). These whales were subsequently described as a new species, 
Rice's whale (Balaenoptera ricei) (Rosel et al., 2021).
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    Although Rice's whales may occur outside of the core habitat area, 
we expect that any such occurrence would be limited to the narrow band 
of suitable habitat described above (i.e., 100-400 m) and that, based 
on the few available records, these occurrences would be rare. 
WesternGeco's planned activities will occur in water depths of 
approximately 1,000-3,000 m in the central GOM. Thus, NMFS does not 
expect there to be the reasonable potential for take of Rice's whale in 
association with this survey and, accordingly, does not authorize take 
of Rice's whale through the LOA.
    Killer whales are the most rarely encountered species in the GOM, 
typically in deep waters of the central GOM (Roberts et al., 2015; 
Maze-Foley and Mullin, 2006). As discussed in the final rule, the 
density models produced by Roberts et al. (2016) provide the best 
available scientific information regarding predicted density patterns 
of cetaceans in the U.S. GOM. The predictions represent the output of 
models derived from multi-year observations and associated 
environmental parameters that incorporate corrections for detection 
bias. However, in the case of killer whales, the model is informed by 
few data, as indicated by the coefficient of variation associated with 
the abundance predicted by the model (0.41, the second-highest of any 
GOM species model; Roberts et al., 2016). The model's authors noted the 
expected non-uniform distribution of this rarely-encountered species 
(as discussed above) and expressed that, due to the limited data 
available to inform the model, it ``should be viewed cautiously'' 
(Roberts et al., 2015). NOAA surveys in the GOM from 1992 to 2009 
reported only 16 sightings of killer whales, with an additional 3 
encounters during more recent survey effort from 2017 to 2018 (Waring 
et al., 2013; https://www.boem.gov/gommapps). Two other species were 
also observed on fewer than 20 occasions during the 1992-2009 NOAA 
surveys (Fraser's dolphin and false killer whale \4\). However, 
observational data collected by protected species observers (PSO) on 
industry geophysical survey vessels from 2002 to 2015 distinguish the 
killer whale in terms of rarity. During this period, killer whales were 
encountered on only 10 occasions, whereas the next most rarely 
encountered species.\4\ However, note that these species have been 
observed over a greater range of water depths in the GOM than have 
killer whales. (Fraser's dolphin) was recorded on 69 occasions 
(Barkaszi and Kelly, 2019). The false killer whale and pygmy killer 
whale were the next most rarely encountered species, with 110 records 
each. The killer whale was the species with the lowest detection 
frequency during each period over which PSO data were synthesized 
(2002-2008 and 2009-2015). This information qualitatively informed our 
rulemaking process, as discussed at 86 FR 5322 and 86 FR 5334 (January 
19, 2021), and similarly informs our analysis here.
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    \4\ However, note that these species have been observed over a 
greater range of water depths in the GOM than have killer whales.
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    The rarity of encounter during seismic surveys is not likely to be 
the product of high bias on the probability of detection. Unlike 
certain cryptic species with high detection bias, such as Kogia spp. or 
beaked whales, or deep-diving species with high availability bias, such 
as beaked whales or sperm whales, killer whales are typically available 
for detection when present and are easily observed. Roberts et al. 
(2015) stated that availability is not a major factor affecting 
detectability of killer whales from shipboard surveys, as they are not 
a particularly long-diving species. Baird et al. (2005) reported that 
mean dive durations for 41 fish-eating killer whales for dives greater 
than or equal to 1 minute in duration was 2.3-2.4 minutes, and Hooker 
et al. (2012) reported that killer whales spent 78 percent of their 
time at depths between 0 and 10 m. Similarly, Kvadsheim et al. (2012) 
reported data from a study of 4 killer whales, noting that the whales 
performed 20 times as many dives 1-30 m in depth than to deeper waters, 
with an average depth during those most common dives of approximately 3 
m.
    In summary, killer whales are the most rarely encountered species 
in the GOM and typically occur only in particularly deep water. This 
survey would take place in deep waters that would overlap with depths 
in which killer whales typically occur. While this information is 
reflected through the density model informing the acoustic exposure 
modeling results, there is relatively high uncertainty associated with 
the model for this species, and the acoustic exposure modeling applies 
mean distribution data over areas where the species is in fact less 
likely to occur. In addition, as noted above in relation to the general 
take estimation methodology, the assumed proxy source (72-element, 
8,000-in\3\ array) results in a significant overestimate of the actual 
potential for take to occur. NMFS' determination in reflection of the 
information discussed above, which informed the final rule, is that use 
of the generic acoustic exposure modeling results for killer whales 
will generally result in estimated take numbers that are inconsistent 
with the assumptions made in the rule regarding expected killer whale 
take (86 FR 5322, January 19, 2021; 86 FR 5403, January 19, 2021).
    In past authorizations, NMFS has often addressed situations 
involving the low likelihood of encountering a rare species such as 
killer whales in the

[[Page 72742]]

GOM through authorization of take of a single group of average size 
(i.e., representing a single potential encounter). See 83 FR 63268, 
December 7, 2018; 86 FR 29090, May 28, 2021; 85 FR 55645, September 9, 
2020. For the reasons expressed above, NMFS determined that a single 
encounter of killer whales is more likely than the model-generated 
estimates and has authorized take associated with a single group 
encounter (i.e., up to seven animals for killer whales).
    Based on the results of our analysis, NMFS has determined that the 
level of taking authorized through the LOA is consistent with the 
findings made for the total taking allowable under the regulations for 
the affected species or stocks of marine mammals. See Table 1 in this 
notice and Table 9 of the rule (86 FR 5322, January 19, 2021).

Small Numbers Determination

    Under the GOM rule, NMFS may not authorize incidental take of 
marine mammals in an LOA if it will exceed ``small numbers.'' In short, 
when an acceptable estimate of the individual marine mammals taken is 
available, if the estimated number of individual animals taken is up 
to, but not greater than, one-third of the best available abundance 
estimate, NMFS will determine that the numbers of marine mammals taken 
of a species or stock are small. For more information please see NMFS' 
discussion of the MMPA's small numbers requirement provided in the 
final rule (86 FR 5438, January 19, 2021).
    The take numbers for authorization are determined as described 
above in the Summary of Request and Analysis section. Subsequently, the 
total incidents of harassment for each species are multiplied by scalar 
ratios to produce a derived product that better reflects the number of 
individuals likely to be taken within a survey (as compared to the 
total number of instances of take), accounting for the likelihood that 
some individual marine mammals may be taken on more than 1 day (see 86 
FR 5404, January 19, 2021). The output of this scaling, where 
appropriate, is incorporated into adjusted total take estimates that 
are the basis for NMFS' small numbers determinations, as depicted in 
Table 1.
    This product is used by NMFS in making the necessary small numbers 
determinations through comparison with the best available abundance 
estimates (see discussion at 86 FR 5322, January 19, 2021; 86 FR 5391, 
January 19, 2021). For this comparison, NMFS' approach is to use the 
maximum theoretical population, determined through review of current 
stock assessment reports (SAR; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-species-stock) and model-predicted abundance information (https://seamap.env.duke.edu/models/Duke/GOM/). For the latter, for taxa where a 
density surface model could be produced, we use the maximum mean 
seasonal (i.e., 3-month) abundance prediction for purposes of 
comparison as a precautionary smoothing of month-to-month fluctuations 
and in consideration of a corresponding lack of data in the literature 
regarding seasonal distribution of marine mammals in the GOM. 
Information supporting the small numbers determinations is provided in 
Table 1.

                                             Table 1--Take Analysis
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                                                    Authorized      Scaled take                       Percent
                     Species                           take             \1\        Abundance \2\     abundance
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Rice's whale....................................               0             n/a              51             n/a
Sperm whale.....................................           1,043             441           2,207            20.0
Kogia spp.......................................         \3\ 426             129           4,373             3.5
Beaked whales...................................           5,374             543           3,768            14.4
Rough-toothed dolphin...........................             946             271           4,853             5.6
Bottlenose dolphin..............................           3,129             898         176,108             0.5
Clymene dolphin.................................           2,611             749          11,895             6.3
Atlantic spotted dolphin........................           1,247             358          74,785             0.5
Pantropical spotted dolphin.....................          15,927           4,571         102,361             4.5
Spinner dolphin.................................           2,430             697          25,114             2.8
Striped dolphin.................................           1,117             321           5,229             6.1
Fraser's dolphin................................             332              95           1,665             5.7
Risso's dolphin.................................             667             197           3,764             5.2
Melon-headed whale..............................           1,706             503           7,003             7.2
Pygmy killer whale..............................             524             155           2,126             7.3
False killer whale..............................             725             214           3,204             6.7
Killer whale....................................               7             n/a             267             2.6
Short-finned pilot whale........................             391             115           1,981             5.8
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\1\ Scalar ratios were applied to ``Authorized Take'' values as described at 86 FR 5322 and 86 FR 5404 (January
  19, 2021) to derive scaled take numbers shown here.
\2\ 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
  Rice's whale and the killer whale, the larger estimated SAR abundance estimate is used.
\3\ Includes 26 takes by Level A harassment and 400 takes by Level B harassment. Scalar ratio is applied to
  takes by Level B harassment only; small numbers determination made on basis of scaled Level B harassment take
  plus authorized Level A harassment take.

    Based on the analysis contained herein of WesternGeco's proposed 
survey activity described in its LOA application and the anticipated 
take of marine mammals, NMFS finds that small numbers of marine mammals 
will be taken relative to the affected species or stock sizes (i.e., 
less than one-third of the best available abundance estimate) and 
therefore the taking is of no more than small numbers.

Authorization

    NMFS has determined that the level of taking for this LOA request 
is consistent with the findings made for the total taking allowable 
under the incidental take regulations and that the amount of take 
authorized under the LOA is of no more than small numbers. Accordingly, 
we have issued an LOA to WesternGeco authorizing the take of

[[Page 72743]]

marine mammals incidental to its geophysical survey activity, as 
described above.

    Dated: October 17, 2023.
Kim Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-23298 Filed 10-20-23; 8:45 am]
BILLING CODE 3510-22-P