[Federal Register Volume 89, Number 67 (Friday, April 5, 2024)]
[Notices]
[Pages 23981-23985]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-07138]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD714]


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 of 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 (GOM).

DATES: The LOA is effective from May 1, 2024 through April 30, 2025.

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: Rachel Wachtendonk, Office of

[[Page 23982]]

Protected Resources, NMFS, (301) 427-8401, [email protected].

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 GOM 
over the course of 5 years (see 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 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 50 CFR 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 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 over Walker Ridge and Green Canyon areas, with 
approximate water depths ranging from approximately 700 to 3,000 meters 
(m). WesternGeco anticipates using a single dual source vessel, either 
towing airgun array sources consisting of 28 elements, with a total 
volume of 5,240 cubic inches (in\3\; 0.086 cubic meters (m\3\)), or a 
Gemini enhanced frequency source (EFS) array. Please see WesternGeco's 
LOA application for additional detail.
    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\ (0.066 m\3\) each (total volume of 8,000 
in\3\ (0.131 m\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. NMFS anticipates 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. Please see prior notices (e.g., 88 FR 72739, October 
23, 2023) for additional detail regarding 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 (see 86 FR 5398, January 19, 2021). In order 
to generate the appropriate take number 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 29212, 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 a single source vessel sailing along 
closely spaced survey lines that are approximately 345 m apart and 
approximately 100 kilometers (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

[[Page 23983]]

WesternGeco is not proposing to perform a survey using the coil 
geometry, its planned 3D OBN survey is expected to cover approximately 
69 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.
    All available acoustic exposure modeling results assume use of a 
72-element, 8,000 in\3\ array. Thus, take numbers authorized through 
the LOA are considered conservative due to differences in the airgun 
array (28 elements, 5,240 in\3\ or Gemini), as compared to the source 
modeled for the rule.
    The survey will take place over approximately 65 days, with 43 days 
in Zone 5 and 22 days in Zone 7. Although WesternGeco plans to conduct 
all 65 survey days in the ``summer'' season, we have calculated 
estimated take numbers based on an assumption that the survey could 
occur in either season in order to accommodate any potential delay of 
survey dates.
    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 modeling zone. Thus, although the modeling conducted for 
the rule is a natural starting point for estimating take, the rule 
acknowledged that other information could be considered (see, e.g., 86 
FR 5322, 5442, 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 its occurrence in the 
GOM. Accordingly, we have adjusted the calculated take estimates for 
these 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 has 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; Garrison et al., 2023), and 
Rice's whales have been detected within this depth band throughout the 
GOM (Soldevilla et al., 2022, 2024). 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 overlap this depth range, with 
approximately 3.6 percent of the area expected to be ensonified by the 
survey above root-mean-squared pressure received levels (RMS SPL) of 
160 decibel (dB) (referenced to 1 micropascal (re 1 [mu]Pa)) 
overlapping the 100-400 m isobaths. Therefore, while we expect take of 
Rice's whale to be unlikely, there is some reasonable potential for 
take of Rice's whale to occur in association with this survey. However, 
NMFS' determination in reflection of the data discussed above, which 
informed the final rule, is that use of the generic acoustic exposure 
modeling results for Rice's whales would result in estimated take 
numbers that are inconsistent with the assumptions made in the rule 
regarding expected Rice's whale take (86 FR 5322, January 19, 2021).
    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). 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 modeling zone. NMFS has 
determined that the approach results in unrealistic projections 
regarding the likelihood of encountering killer whales.
    As discussed in the final rule, the density models produced by 
Roberts et al. (2016) 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 1992-2009 reported only 16 sightings 
of killer whales, with an additional 3 encounters during more recent 
survey effort from 2017-2018 (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 (PSOs) on industry geophysical survey 
vessels from 2002-2015 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 (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 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 encounters 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

[[Page 23984]]

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 0-10 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 (>700 
m). 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. NMFS' determination in reflection of the data 
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 5403, January 19, 2021).
    In past authorizations, NMFS has often addressed situations 
involving the low likelihood of encountering a rare species, such as 
Rice's whales and killer whales in the 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. See also 86 FR 
29090, May 28, 2021 and 85 FR 55645, September 9, 2020. For the reasons 
expressed above, NMFS determined that a single encounter of Rice's 
whales and killer whales are more likely than the model-generated 
estimates and has authorized take associated with a single group 
encounter (i.e., up to two animals for Rice's whales and up to seven 
animals for killer whales).
    Based on the results of our analysis, NMFS has determined that the 
level of taking expected for this survey and authorized through the LOA 
is consistent with the findings made for the total taking allowable 
under the regulations. 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 (see 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 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-assessments) 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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                                                                    Scaled take                       Percent
                    Species                      Authorized take        \1\        Abundance \2\     abundance
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Rice's whale \3\..............................                 2             n/a              51             7.0
Sperm whale...................................             1,248           527.7           2,207            23.9
Kogia spp.....................................           \4\ 493           149.2           4,373             4.1
Beaked whales.................................             6,021           608.1           3,768            16.1
Rough-toothed dolphin.........................             1,050           301.2           4,853             6.2
Bottlenose dolphin............................             4,072         1,168.7         176,108             0.7
Clymene dolphin...............................             2,920           838.0          11,895             7.0
Atlantic spotted dolphin......................             1,625           466.2          74,785             0.6
Pantropical spotted dolphin...................            15,971         4,583.6         102,361             4.5
Spinner dolphin...............................             3,054           876.6          25,114             3.5
Striped dolphin...............................             1,206           346.0           5,229             6.6
Fraser's dolphin..............................               354           101.5           1,665             6.1
Risso's dolphin...............................               791           233.3           3,764             6.2
Melon-headed whale............................             1,912           564.1           7,003             8.1
Pygmy killer whale............................               532           156.9           2,126             7.4
False killer whale............................               773           228.1           3,204             7.1
Killer whale..................................                 7             n/a             267             3.4

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Short-finned pilot whale......................               485           143.0           1,981             7.2
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\1\ Scalar ratios were applied to ``Authorized Take'' values as described at 86 FR 5322, 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 killer whale, the larger estimated SAR abundance estimate is used.
\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).
\4\ Includes 28 takes by Level A harassment and 465 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 marine 
mammals incidental to its geophysical survey activity, as described 
above.

    Dated: March 28, 2024.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2024-07138 Filed 4-4-24; 8:45 am]
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