88 FR 91 pgs. 30282-30299 - Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey Off North Carolina in the Northwest Atlantic Ocean
Type: NOTICEVolume: 88Number: 91Pages: 30282 - 30299
Pages: 30282, 30283, 30284, 30285, 30286, 30287, 30288, 30289, 30290, 30291, 30292, 30293, 30294, 30295, 30296, 30297, 30298, 30299Docket number: [RTID 0648-XC977]
FR document: [FR Doc. 2023-10024 Filed 5-10-23; 8:45 am]
Agency: Commerce Department
Sub Agency: National Oceanic and Atmospheric Administration
Official PDF Version: PDF Version
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XC977]
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey Off North Carolina in the Northwest Atlantic Ocean
AGENCY:
National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.
ACTION:
Notice; issuance of an incidental harassment authorization.
SUMMARY:
In accordance with the regulations implementing the Marine Mammal Protection Act (MMPA) as amended, notification is hereby given that NMFS has issued an incidental harassment authorization (IHA) to Lamont-Doherty Earth Observatory (L-DEO) to incidentally harass marine mammals during survey activities associated with a marine geophysical survey off North Carolina in the Northwest Atlantic Ocean.
DATES:
This Authorization is effective from May 5, 2023 through May 4, 2024.
FOR FURTHER INFORMATION CONTACT:
Rachel Wachtendonk, 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: www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. 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 IHA is provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other "means of effecting the least practicable adverse impact" on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for 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
[top] On October 12, 2022, NMFS received a request from L-DEO for an IHA to take marine mammals incidental to a marine geophysical survey off the coast of North Carolina in the northwest Atlantic Ocean. The application was deemed adequate and complete on January 13, 2023. L-DEO requested authorization for the take of 30 species of marine mammals by Level B harassment and, for 2 of these species, by Level A harassment. The proposed IHA was published on March 23, 2023 (88 FR 17646). Neither L-DEO, nor NMFS expect serious injury or mortality to result from this activity and, therefore, an IHA is appropriate.
Description of Activity
Overview
Researchers from the University of Texas at Austin (UT) and L-DEO, with funding from the NSF, and in collaboration with international and domestic researchers including the United States Geological Survey (USGS), propose to conduct research, including high-energy seismic surveys using airguns as the acoustic source, from the research vessel (R/V) Marcus G. Langseth ( Langseth ). The survey will occur off North Carolina in the northwestern Atlantic Ocean during spring/summer 2023. The multi-channel seismic (MCS) reflection survey will occur within the Exclusive Economic Zone (EEZ) of the United States and in international waters, in depths ranging from 200 to 5,500 meters (m). To complete this survey, the R/V Langseth will tow an 18-airgun array consisting of Bolt airguns ranging from 40-360 cubic inch (in 3 ) each on two strings spaced 6 m apart, with a total discharge volume of 3,300 in 3 . The acoustic source will be towed at 6 m deep along the survey lines, while the receiving system will consist of a 5 kilometer (km) solid-state hydrophone streamer towed at a depth of 6 m and a 600 m long solid-state hydrophone streamer towed at a depth of 2 to 3 m.
Dates and Duration
The survey is expected to last for 33 days, with approximately 28 days of seismic operations, 3 days of piston coring and heat flow measurements, and 2 days of transit. R/V Langseth will likely leave from and return to port in Norfolk, VA, during spring/summer 2023.
Specific Geographic Region
The survey will occur within ~31-35° N lat., ~72-75° W long. off the coast of North Carolina in the Northwest Atlantic Ocean. The closest point of approach of the survey area to the coast will be approximately 40 km (from Cape Hatteras, North Carolina). The region where the survey is planned to occur is depicted in Figure 1; the tracklines could occur anywhere within the polygon shown in Figure 1. Representative survey tracklines are shown, however, some deviation in actual tracklines, including the order of survey operations, could be necessary for reasons such as science drivers, poor data quality, inclement weather, or mechanical issues with the research vessel and/or equipment. The surveys are planned to occur within the EEZ of the U.S. and in international waters, in depths ranging from 200-5,500 m deep.
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[Federal Register graphic "EN11MY23.008" is not available. Please view the graphic in the PDF version of this document.]
A detailed description of the planned geophysical survey is provided in the Federal Register notice for the proposed IHA (88 FR 17646, March 23, 2023). Since that time, no changes have been made to the planned survey activities. Therefore, a detailed description is not provided here. Please refer to that Federal Register notice for the description of the specific activity.
Comments and Responses
A notice of proposed IHA was published to the Federal Register on March 23, 2023 (88 FR 17646). That notice described, in detail, L-DEO's activity, the marine mammal species that may be affected by the activity, and the anticipated effects on marine mammals. During the 30-day public comment period, NMFS did not receive any public comments.
Changes From the Proposed IHA to Final IHA
Changes were made between publication of the notice of proposed IHA and this notice of final IHA. Additional reporting has been required to notify NOAA's Southeast Regional Office (SERO) on the start and end date of seismic operations, as well as providing daily observations if any non-seismic activities are conducted between November and April (note that use of airguns is prohibited during this period). Specific language regarding the 10-knot (kn) speed restrictions in Seasonal and Dynamic Management Areas (SMA and DMA) for North Atlantic right whale protection was added under the vessel strike avoidance regulations. Lastly, the contact information for the NMFS North Atlantic Right Whale Sighting Advisory System was corrected.
Description of Marine Mammals in the Area of Specified Activities
[top] Sections 3 and 4 of L-DEO's application summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history, of the potentially affected species. Additional information regarding population trends and threats may be found in NMFS' Stock Assessment Reports (SARs; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments ) and more general information about these species ( e.g., physical and behavioral descriptions) may be found on NMFS' website ( www.fisheries.noaa.gov/find-species ). NMFS refers the reader to the application and to the aforementioned
Table 1 lists all species or stocks for which take is expected and authorized for this activity, and summarizes information related to the population or stock, including regulatory status under the MMPA and Endangered Species Act (ESA) and potential biological removal (PBR), where known. PBR is defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population (as described in NMFS' SARs). While no serious injury or mortality is expected to occur, PBR and annual serious injury and mortality from anthropogenic sources are included here as gross indicators of the status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS' stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. All stocks managed under the MMPA in this region are assessed in NMFS' U.S. Atlantic and Gulf of Mexico SARs ( e.g., Hayes et al., 2019, 2020, 2022). All values presented in Table 1 are the most recent available (including the draft 2022 SARs) at the time of publication and are available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.
| Common name | Scientific name | Stock | ESA/MMPA status; strategic (Y/N)? 1 | Stock abundance (CV, N min , most recent abundance survey)? 2 | PBR | Annual M/SI? 3 |
|---|---|---|---|---|---|---|
| Order Cetartiodactyla-Cetacea-Superfamily Mysticeti (baleen whales) | ||||||
| Family Balaenopteridae (rorquals): | ||||||
| Humpback whale | Megaptera novaeangliae | Gulf of Maine | -/-; N | 1,396 (0; 1,380; 2016) | 22 | 12.15 |
| Fin whale | Balaenoptera physalus | Western North Atlantic | E/D; Y | 6,802 (0.24; 5,573; 2016) | 11 | 1.8 |
| Sei whale | Balaenoptera borealis | Nova Scotia | E/D; Y | 6,292 (1.02; 3,098; 2016) | 6.2 | 0.8 |
| Minke whale | Balaenoptera acutorostrata | Canadian East Coast | -/-; N | 21,968 (0.31; 17,002; 2016) | 170 | 10.6 |
| Blue whale | Balaenoptera musculus | Western North Atlantic | E/D;Y | unk (unk; 402; 1980-2008) | 0.8 | 0 |
| Superfamily Odontoceti (toothed whales, dolphins, and porpoises) | ||||||
| Family Physeteridae: | ||||||
| Sperm whale | Physeter macrocephalus | North Atlantic | E/D;Y | 4,349 (0.28; 3,451; 2016) | 3.9 | 0 |
| Family Kogiidae: | ||||||
| Pygmy sperm whale | Kogia breviceps | Western North Atlantic | -/-; N | 7,750 (0.38; 5,689; 2016) | 46 | 0 |
| Dwarf sperm whale | Kogia sima | Western North Atlantic | -/-; N | 7,750 (0.38; 5,689; 2016) | 46 | 0 |
| Family Ziphiidae (beaked whales): | ||||||
| Cuvier's beaked Whale | Ziphius cavirostris | Western North Atlantic | -/-; N | 5,744 (0.36; 4,282; 2016) | 43 | 0.2 |
| Blainville's beaked Whale | Mesoplodon densirostris | Western North Atlantic | -/-; N | 10,107 (0.27; 8,085; 2016) | 81 | 0 |
| True's beaked whale | Mesoplodon mirus | Western North Atlantic | -/-; N | 10,107 (0.27; 8,085; 2016) | 81 | 0 |
| Gervais' beaked whale | Mesoplodon europaeus | Western North Atlantic | -/-; N | 10,107 (0.27; 8,085; 2016) | 81 | 0 |
| Family Delphinidae: | ||||||
| Long-finned pilot whale | Globicephala melas | Western North Atlantic | -/-; N | 39,215 (0.30; 30,627; 2016) | 306 | 9 |
| Short finned pilot whale | Globicephala macrorhynchus | Western North Atlantic | -/-;Y | 28,924 (0.24; 23,637; 2016) | 236 | 136 |
| Rough-toothed dolphin | Steno bredanensis | Western North Atlantic | -/-; N | 136 (1.0; 67; 2016) | 0.7 | 0 |
| Bottlenose dolphin | Tursiops truncates | Western North Atlantic Offshore | -/-; N | 62,851 (0.23; 51,914; 2016) | 519 | 28 |
| Atlantic white-sided dolphin | Lagenorhynchus acutus | Western North Atlantic | -/-; N | 93,233 (0.71; 54,443; 2016) | 544 | 27 |
| Pantropical spotted dolphin | Stenella attenuate | Western North Atlantic | -/-; N | 6,593 (0.52; 4,367; 2016) | 44 | 0 |
| Atlantic spotted dolphin | Stenella frontalis | Western North Atlantic | -/-; N | 39,921 (0.27; 32,032; 2016) | 320 | 0 |
| Spinner dolphin | Stenella longirostris | Western North Atlantic | -/-; N | 4,102 (0.99; 2,045; 2016) | 21 | 0 |
| Clymene dolphin | Stenella clymene | Western North Atlantic | -/-; N | 4,237 (1.03; 2,071; 2016) | 21 | 0 |
| Striped dolphin | Stenella coeruleoalba | Western North Atlantic | -/-; N | 67,036 (0.29; 52,939; 2016) | 529 | 0 |
| Fraser's dolphin | Lagenodelphis hosei | Western North Atlantic | -/-; N | unk | unk | 0 |
| Risso's dolphin | Grampus griseus | Western North Atlantic | -/-; N | 35,215(0.19; 30,051; 2016) | 301 | 34 |
| Common dolphin | Delphinus delphis | Western North Atlantic | -/-; N | 172,947 (0.21; 145,216; 2016) | 1,452 | 390 |
| Melon-headed whale | Peponocephala electra | Western North Atlantic | -/-; N | unk | unk | 0 |
| Pygmy killer whale | Feresa attenuate | Western North Atlantic | -/-; N | unk | unk | 0 |
| False killer whale | Pseudorca crassidens | Western North Atlantic | -/-; N | 1,791 (0.56; 1,154; 2016) | 12 | 0 |
| Killer whale | Orcinus orca | Western North Atlantic | -/-; N | unk | unk | 0 |
| Family Phocoenidae (porpoises): | ||||||
| Harbor porpoise | Phocoena phocoena | Gulf of Maine/Bay of Fundy | -/-; N | 95,543 (0.31; 74,034; 2016) | 851 | 164 |
| 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: https://www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; N min is the minimum estimate of stock abundance. | ||||||
| 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 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. | ||||||
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As indicated above, all 30 species in Table 1 temporally and spatially co-occur with the activity to the degree that take is reasonably likely to occur. Species that could potentially occur in the research area but are not likely to be harassed due to the rarity of their occurrence ( i.e., are considered extralimital or rare visitors to the waters off North Carolina), or because their known migration through the area does not align with the survey dates, were omitted.
A detailed description of the of the species likely to be affected by the geophysical survey, including brief introductions to the species and relevant stocks as well as available information regarding population trends and threats, and information regarding local occurrence, were provided in the Federal Register notice for the proposed IHA (88 FR 17646, March 23, 2023). Since that time, we are not aware of any changes in the status of these species and stocks; therefore, detailed descriptions are not provided here. Please refer to that Federal Register notice for these descriptions. Please also refer to NMFS' website ( https://www.fisheries.noaa.gov/find-species ) for generalized species accounts.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Not all marine mammal species have equal hearing capabilities ( e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007, 2019) recommended that marine mammals be divided into hearing groups based on directly measured (behavioral or auditory evoked potential techniques) or estimated hearing ranges (behavioral response data, anatomical modeling, etc. ). Note that no direct measurements of hearing ability have been successfully completed for mysticetes ( i.e., low-frequency 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.
| Hearing group | Generalized hearing range?* |
|---|---|
| Low-frequency (LF) cetaceans (baleen whales) | 7 Hz to 35 kHz. |
| Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) | 150 Hz to 160 kHz. |
| High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, Cephalorhynchid, Lagenorhynchus cruciger & L. australis ) | 275 Hz to 160 kHz. |
| Phocid pinnipeds (PW) (underwater) (true seals) | 50 Hz to 86 kHz. |
| Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) | 60 Hz to 39 kHz. |
| *?Represents the generalized hearing range for the entire group as a composite ( i.e., all species within the group), where individual species' hearing ranges are typically not as broad. Generalized hearing range chosen based on ~65 dB threshold from normalized composite audiogram, with the exception for lower limits for LF cetaceans (Southall et al., 2007) and PW pinniped (approximation). | |
For more detail concerning these groups and associated frequency ranges, please see NMFS (2018) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their Habitat
The effects of underwater noise from L-DEO's survey activities have the potential to result in harassment of marine mammals in the vicinity of the survey area. The notice of proposed IHA (88 FR 17646, March 23, 2023) included a discussion of the effects of anthropogenic noise on marine mammals and the potential effects of underwater noise from L-DEO on marine mammals and their habitat. That information and analysis is not repeated here; please refer to the notice of proposed IHA (88 FR 17646, March 23, 2023).
Estimated Take
This section provides an estimate of the number of incidental takes authorized through the IHA, which will inform both NMFS' consideration of "small numbers," and the negligible impact determinations.
Harassment is the only type of take expected to result from these activities. Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines "harassment" as any act of pursuit, torment, or annoyance, which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B harassment).
Authorized takes will primarily be Level B harassment, as use of the described acoustic sources, particularly airgun arrays, is likely to disrupt behavioral patterns of marine mammals. There is also some potential for auditory injury (Level A harassment) to result for low- and high-frequency species due to the size of the predicted auditory injury zones for those species. Auditory injury is less likely to occur for mid-frequency species, due to their relative lack of sensitivity to the frequencies at which the primary energy of an airgun signal is found, as well as such species' general lower sensitivity to auditory injury as compared to high-frequency cetaceans. As discussed in further detail below, we do not expect auditory injury for low- or mid-frequency cetaceans. The mitigation and monitoring measures are expected to minimize the severity of such taking to the extent practicable. No mortality is anticipated as a result of these activities. Below, we describe how the take numbers are estimated.
[top] For acoustic impacts, generally speaking, we estimate take by considering: (1) acoustic thresholds above which NMFS believes the best available science indicates marine mammals will be behaviorally harassed or incur some degree of permanent hearing impairment; (2) the area or volume of water that will be ensonified
Acoustic Thresholds
NMFS recommends the use of acoustic thresholds that identify the received level of underwater sound above which exposed marine mammals would be reasonably expected to be behaviorally harassed (equated to Level B harassment) or to incur permanent threshold shift (PTS) of some degree (equated to Level A harassment).
Level B Harassment -Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source or exposure context ( e.g., frequency, predictability, duty cycle, duration of the exposure, signal-to-noise ratio, distance to the source), the environment ( e.g., bathymetry, other noises in the area, predators in the area), and the receiving animals (hearing, motivation, experience, demography, life stage, depth) and can be difficult to predict ( e.g., Southall et al., 2007, 2021; Ellison et al., 2012). Based on what the available science indicates and the practical need to use a threshold based on a metric that is both predictable and measurable for most activities, NMFS typically uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS generally predicts that marine mammals are likely to be behaviorally harassed in a manner considered to be Level B harassment when exposed to underwater anthropogenic noise above root-mean-squared pressure received levels (RMS SPL) of 120 dB (referenced to 1 micropascal (re 1 µPa)) for continuous ( e.g., vibratory pile-driving, drilling) and above RMS SPL 160 dB re 1 µPa for non-explosive impulsive ( e.g., seismic airguns) or intermittent ( e.g., scientific sonar) sources. Generally speaking, Level B harassment take estimates based on these behavioral harassment thresholds are expected to include any likely takes by temporary threshold shift (TTS) as, in most cases, the likelihood of TTS occurs at distances from the source less than those at which behavioral harassment is likely. TTS of a sufficient degree can manifest as behavioral harassment, as reduced hearing sensitivity and the potential reduced opportunities to detect important signals (conspecific communication, predators, prey) may result in changes in behavior patterns that would not otherwise occur.
L-DEO's survey includes the use of impulsive seismic sources ( e.g., airguns), and therefore the 160 dB re 1 µPa is applicable for analysis of Level B harassment.
Level A harassment -NMFS' Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual criteria to assess auditory injury (Level A harassment) to five different marine mammal groups (based on hearing sensitivity) as a result of exposure to noise from two different types of sources (impulsive or non-impulsive). L-DEO's survey includes the use of impulsive seismic sources ( e.g., airguns).
These thresholds are provided in the table below. The references, analysis, and methodology used in the development of the thresholds are described in NMFS' 2018 Technical Guidance, which may be accessed at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance .
| Hearing group | PTS onset acoustic thresholds?* (received level) | Impulsive | Non-impulsive |
|---|---|---|---|
| Low-Frequency (LF) Cetaceans | Cell 1: L pk,flat : 219 dB; L E,LF,24h : 183 dB | Cell 2: L E,LF,24h : 199 dB. | |
| Mid-Frequency (MF) Cetaceans | Cell 3: L pk,flat : 230 dB; L E,MF,24h : 185 dB | Cell 4: L E,MF,24h : 198 dB. | |
| High-Frequency (HF) Cetaceans | Cell 5: L pk,flat : 202 dB; L E,HF,24h : 155 dB | Cell 6: L E,HF,24h : 173 dB. | |
| Phocid Pinnipeds (PW) (Underwater) | Cell 7: L pk,flat : 218 dB; L E,PW,24h : 185 dB | Cell 8: L E,PW,24h : 201 dB. | |
| Otariid Pinnipeds (OW) (Underwater) | Cell 9: L pk,flat : 232 dB; L E,OW,24h : 203 dB | Cell 10: L E,OW,24h : 219 dB. | |
| *?Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should also be considered. | |||
| Note: Peak sound pressure ( L pk ) has a reference value of 1 µPa, and cumulative sound exposure level ( L E ) has a reference value of 1µPa 2 s. In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI, 2013). However, peak sound pressure is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript "flat" is being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be exceeded in a multitude of ways ( i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be exceeded. | |||
Ensonified Area
Here, we describe operational and environmental parameters of the activity that are used in estimating the area ensonified above the acoustic thresholds, including source levels and transmission loss coefficient.
[top] When the NMFS Technical Guidance (2016) was published, in recognition of the fact that ensonified area/volume could be more technically challenging to predict because of the duration component in the new thresholds, we developed a User Spreadsheet that includes tools to help predict a simple isopleth that can be used in conjunction with marine mammal density or occurrence to help predict takes. We note that because of some of the assumptions included in the methods used for these tools, we anticipate that isopleths produced are typically going to be overestimates of some degree, which may result in some degree of overestimate of Level A harassment take. However, these tools offer the best way to predict appropriate isopleths
The survey will entail the use of a 18-airgun array with a total discharge of 3300 in 3 at a tow depth of 6 m. L-DEO model results are used to determine the 160 dB rms radius for the 18-airgun array in water depth ranging from 200-5500 m. Received sound levels were predicted by L-DEO's model (Diebold et al., 2010) as a function of distance from L-DEO's full 36 airgun array (versus the smaller array planned for use here). Models for the 36-airgun array used a 12-m tow depth, versus the 6-m tow depth planned for this survey. This modeling approach uses ray tracing for the direct wave traveling from the array to the receiver and its associated source ghost (reflection at the air-water interface in the vicinity of the array), in a constant velocity half-space (infinite homogeneous ocean layer, unbounded by a seafloor). In addition, propagation measurements of pulses from the 36-airgun array at a tow depth of 6 m have been reported in deep water (~1600 m), intermediate water depth on the slope (~600-1100 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 harassment isopleths, as at those sites the calibration hydrophone was located at a roughly constant depth of 350-550 m, which may not intersect all the SPL isopleths at their widest point from the sea surface down to the maximum relevant water depth (~2,000 m) for marine mammals. At short ranges, where the direct arrivals dominate and the effects of seafloor interactions are minimal, the data at the deep sites are suitable for comparison with modeled levels at the depth of the calibration hydrophone. At longer ranges, the comparison with the model-constructed from the maximum SPL through the entire water column at varying distances from the airgun array-is the most relevant.
In deep and intermediate water depths at short ranges, sound levels for direct arrivals recorded by the calibration hydrophone and L-DEO model results for the same array tow depth are in good alignment (see Figures 12 and 14 in Appendix H of the NSF-USGS PEIS). Consequently, isopleths falling within this domain can be predicted reliably by the L-DEO model, although they may be imperfectly sampled by measurements recorded at a single depth. At greater distances, the calibration data show that seafloor-reflected and sub-seafloor-refracted arrivals dominate, whereas the direct arrivals become weak and/or incoherent (see Figures 11, 12, and 16 in Appendix H of the NSF-USGS PEIS). Aside from local topography effects, the region around the critical distance is where the observed levels rise closest to the model curve. However, the observed sound levels are found to fall almost entirely below the model curve. Thus, analysis of the Gulf of Mexico calibration measurements demonstrates that although simple, the L-DEO model is a robust tool for conservatively estimating isopleths.
The survey will acquire data with the 18-airgun array at a tow depth of 6 m. For deep water (>1,000 m), we use the deep-water radii obtained from L-DEO model results down to a maximum water depth of 2,000 m for the 18-airgun array. The radii for intermediate water depths (100-1,000 m) are derived from the deep-water ones by applying a correction factor (multiplication) of 1.5, such that observed levels at very near offsets fall below the corrected mitigation curve (see Figure 16 in Appendix H of PEIS).
L-DEO's modeling methodology is described in greater detail in the IHA application. The estimated distances to the Level B harassment isopleth for the airgun configuration are shown in Table 4.
| Airgun configuration | Tow depth (m) | Water depth (m) | Predicted distances (in m) to the level B harassment threshold |
|---|---|---|---|
| 18 airguns, 3300 in? 3 | 6 | >1000 m 100-1000 m | a ?2,886 b ?4,329 |
| a ?Distance is based on L-DEO model results. | |||
| b ?Distance is based on L-DEO model results with a 1.5 × correction factor between deep and intermediate water depths. | |||
Table 5 presents the modeled PTS isopleths for each marine mammal hearing group based on L-DEO modeling incorporated in the companion User Spreadsheet (NMFS 2018).
| LF | MF | HF | |
|---|---|---|---|
| PTS SEL cum | 101.9 | 0 | 0.5 |
| PTS Peak | 23.3 | 11.2 | 116.9 |
| Note: The largest distance (in bold) of the dual criteria (Sound Exposure Level (SEL) cum or Peak) was used to estimate threshold distances and potential takes by Level A harassment. | |||
[top] Predicted distances to Level A harassment isopleths, which vary based on marine mammal hearing groups, were calculated based on modeling performed by L-DEO using the Nucleus software program and the NMFS User Spreadsheet, described below. The acoustic thresholds for impulsive sounds ( e.g., airguns) contained in the Technical Guidance were presented as dual metric acoustic thresholds using both SEL cum and peak sound pressure
The SEL cum for the 18-airgun array is derived from calculating the modified farfield signature. The farfield signature is often used as a theoretical representation of the source level. To compute the farfield signature, the source level is estimated at a large distance (right) below the array ( e.g., 9 km), and this level is back projected mathematically to a notional distance of 1 m from the array's geometrical center. However, it has been recognized that the source level from the theoretical farfield signature is never physically achieved at the source when the source is an array of multiple airguns separated in space (Tolstoy et al., 2009). Near the source (at short ranges, distances <1 km), the pulses of sound pressure from each individual airgun in the source array do not stack constructively as they do for the theoretical farfield signature. The pulses from the different airguns spread out in time such that the source levels observed or modeled are the result of the summation of pulses from a few airguns, not the full array (Tolstoy et al., 2009). At larger distances, away from the source array center, sound pressure of all the airguns in the array stack coherently, but not within one time sample, resulting in smaller source levels (a few dB) than the source level derived from the farfield signature. Because the farfield signature does not take into account the large array effect near the source and is calculated as a point source, the farfield signature is not an appropriate measure of the sound source level for large arrays. See the application for further detail on acoustic modeling.
Auditory injury is unlikely to occur for mid-frequency cetaceans given very small modeled zones of injury for those species, in context of distributed source dynamics. The source level of the array is a theoretical definition assuming a point source and measurement in the far-field of the source (MacGillivray, 2006). As described by Caldwell and Dragoset (2000), an array is not a point source, but one that spans a small area. In the far-field, individual elements in arrays will effectively work as one source because individual pressure peaks will have coalesced into one relatively broad pulse. The array can then be considered a "point source." For distances within the near-field, i.e., approximately 2-3 times the array dimensions, pressure peaks from individual elements do not arrive simultaneously because the observation point is not equidistant from each element. The effect is destructive interference of the outputs of each element, so that peak pressures in the near-field will be significantly lower than the output of the largest individual element. Here, the relevant peak isopleth distances will in all cases be expected to be within the near-field of the array where the definition of source level breaks down. Therefore, actual locations within this distance of the array center where the sound level exceeds the relevant peak SPL thresholds would not necessarily exist. In general, Caldwell and Dragoset (2000) suggest that the near-field for airgun arrays is considered to extend out to approximately 250 m.
In order to provide quantitative support for this theoretical argument, we calculated expected maximum distances at which the near-field would transition to the farfield (Table 5). For a specific array, one can estimate the distance at which the near-field transitions to the farfield by:
[Federal Register graphic "EN11MY23.009" is not available. Please view the graphic in the PDF version of this document.]
with the condition that D >> ?, and where D is the distance, L is the longest dimension of the array, and ? is the wavelength of the signal (Lurton, 2002). Given that ? can be defined by:
[Federal Register graphic "EN11MY23.010" is not available. Please view the graphic in the PDF version of this document.]
where f is the frequency of the sound signal and v is the speed of the sound in the medium of interest, one can rewrite the equation for D as:
[Federal Register graphic "EN11MY23.011" is not available. Please view the graphic in the PDF version of this document.]
and calculate D directly given a particular frequency and known speed of sound (here assumed to be 1,500 meters per second in water, although this varies with environmental conditions).
To determine the closest distance to the arrays at which the source level predictions in Table 5 are valid ( i.e., maximum extent of the near-field), we calculated D based on an assumed frequency of 1 kHz. A frequency of 1 kHz is commonly used in near-field/farfield calculations for airgun arrays (Zykov and Carr, 2014; MacGillivray, 2006; NSF and USGS, 2011), and based on representative airgun spectrum data and field measurements of an airgun array used on the Langseth, nearly all (greater than 95 percent) of the energy from airgun arrays is below 1 kHz (Tolstoy et al., 2009). Thus, using 1 kHz as the upper cut-off for calculating the maximum extent of the near-field should reasonably represent the near-field extent in field conditions.
[top] If the largest distance to the peak sound pressure level threshold was equal to or less than the longest dimension of the array ( i.e., under the array), or within the near-field, then received levels that meet or exceed the threshold in most cases are not expected to occur. This is because within the near-field and within the dimensions of the array, the source levels specified in Appendix A of L-DEO's application are overestimated and not applicable. In fact, until one reaches a distance of approximately three or four times the near-field distance, the average intensity of sound at any given distance from the array is still less than that based on calculations that assume a directional point source (Lurton, 2002). The 3,300-in 3 airgun array planned for use during the survey has an approximate diagonal of 18.6 m, resulting in a near-field distance of approximately 58 m at 1 kHz (NSF and USGS, 2011). Field measurements of this array indicate that the source behaves like multiple discrete sources, rather than a directional point source, beginning at approximately 400 m (deep site) to 1 km (shallow site) from the center of the array (Tolstoy et al., 2009), distances that are actually greater than four times the calculated 58-m near-field distance. Within these distances, the recorded received levels were always lower than would be predicted based on calculations that assume a directional point source, and increasingly so as one moves closer towards the array (Tolstoy et al., 2009). Given this, relying on the calculated distance (58 m) as the distance at which we expect to be in the near-field is a conservative approach since even beyond this distance the acoustic modeling still overestimates
In consideration of the received sound levels in the near-field as described above, we expect the potential for Level A harassment of mid-frequency cetaceans to be minimal, even before the likely moderating effects of aversion and/or other compensatory behaviors ( e.g., Nachtigall et al., 2018) are considered. We do not believe that Level A harassment is a likely outcome for any low- or mid-frequency cetacean and do not propose to authorize any Level A harassment for these species.
The Level A and Level B harassment estimates are based on a consideration of the number of marine mammals that could be within the area around the operating airgun array where received levels of sound =160 dB re 1 µParms are predicted to occur (see Table 1). The estimated numbers are based on the densities (numbers per unit area) of marine mammals expected to occur in the area in the absence of seismic surveys. To the extent that marine mammals tend to move away from seismic sources before the sound level reaches the criterion level and tend not to approach an operating airgun array, these estimates likely overestimate the numbers actually exposed to the specified level of sound.
Marine Mammal Occurrence
In this section we provide information about the occurrence of marine mammals, including density or other relevant information that will inform the take calculations.
Habitat-based density models produced by the Duke University Marine Geospatial Ecology Laboratory (Roberts et al., 2016; Roberts and Halpin, 2022) represent the best available information regarding marine mammal densities in the survey area. The density data presented by Roberts et al. (2016 and 2022) incorporates aerial and shipboard line-transect survey data from NMFS and other organizations and incorporates data from 8 physiographic and 16 dynamic oceanographic and biological covariates, and controls for the influence of sea state, group size, availability bias, and perception bias on the probability of making a sighting. These density models were originally developed for all cetacean taxa in the U.S. Atlantic (Roberts et al., 2016). In subsequent years, certain models have been updated based on additional data as well as certain methodological improvements. More information is available online at https://seamap.env.duke.edu/models/Duke/EC /. Marine mammal density estimates in the survey area (animals/km 2 ) were obtained using the most recent model results for all taxa (Roberts et al., 2016 and 2022).
Monthly density grids ( e.g., rasters) for each species were overlaid with the Survey Area and values from all grid cells that overlapped the Survey Area (plus a 40 km buffer) were averaged to determine monthly mean density values for each species. Monthly mean density values within the Survey Area were averaged for each of the two water depth categories (intermediate and deep) for the months May to October. The highest mean monthly density estimates for each species were used to estimate take.
Take Estimation
Here, we describe how the information provided above is synthesized to produce a quantitative estimate of the take that is reasonably likely to occur and is authorized. In order to estimate the number of marine mammals predicted to be exposed to sound levels that would result in Level A or Level B harassment, radial distances from the airgun array to the predicted isopleth corresponding to the Level A harassment and Level B harassment thresholds are calculated, as described above. Those radial distances are then used to calculate the area(s) around the airgun array predicted to be ensonified to sound levels that exceed the harassment thresholds. The distance for the 160-dB Level B harassment threshold and PTS (Level A harassment) thresholds (based on L-DEO model results) was used to draw a buffer around the area expected to be ensonified ( i.e., the survey area). The ensonified areas were then increased by 25 percent to account for potential delays, which is the equivalent to adding 25 percent to the planned line km to be surveyed. The highest mean monthly density for each species was then multiplied by the daily ensonified areas, increased by 25 percent, and then multiplied by the number of survey days (28) to estimate potential takes (see Appendix B of L-DEO's application for more information).
L-DEO generally assumed that their estimates of marine mammal exposures above harassment thresholds equate to take and requested authorization of those takes. Those estimates in turn form the basis for our authorized take numbers. For the species for which NMFS does not expect there to be a reasonable potential for take by Level A harassment to occur, i.e., mid-frequency cetaceans, we have added L-DEO's estimated exposures above Level A harassment thresholds to their estimated exposures above the Level B harassment threshold to produce a total number of incidents of take by Level B harassment that is planned for authorization. Estimated exposures and take numbers for authorization are shown in Table 6.
[top]
| Species | Stock | Estimated take | Level B | Level A | Authorized take | Level B | Level A | Stock abundance | Percent of stock |
|---|---|---|---|---|---|---|---|---|---|
| North Atlantic right whale | Western North Atlantic | 0.03 | 0 | 0 | 0 | 368 | n/a | ||
| Humpback whale | Gulf of Maine | 0.06 | 0 | 1 ?2 | 0 | 1,396 | 0.14 | ||
| Fin whale | Western North Atlantic | 4 | 0 | 4 | 0 | 6,802 | 0.06 | ||
| Sei whale | Nova Scotia | 8 | 0 | 8 | 0 | 6,292 | 0.13 | ||
| Minke whale | Canadian East Coast | 10 | 0 | 10 | 0 | 21,968 | 0.05 | ||
| Blue whale | Western North Atlantic | 1 | 0 | 1 | 0 | 402 | 0.17 | ||
| Sperm whale | North Atlantic | 405 | 1 | 406 | 0 | 4,349 | 9.34 | ||
| Kogia spp. | 678 | 31 | 678 | 31 | 15,500 | 0.04 | |||
| Cuvier's beaked whale | Western North Atlantic | 394 | 2 | 396 | 0 | 5,744 | 6.89 | ||
| Mesoplodont Beaked whales | 418 | 2 | 420 | 0 | 30,321 | 1.38 | |||
| Pilot whales | 384 | 1 | 385 | 0 | 15,500 | 2.48 | |||
| Rough-toothed dolphin | Western North Atlantic | 82 | 0 | 82 | 0 | 136 | 10.79 | ||
| Bottlenose dolphin | Western North Atlantic Offshore | 1,473 | 4 | 1,477 | 0 | 62,851 | 2.35 | ||
| Atlantic white-sided dolphin | Western North Atlantic | 0 | 0 | 1 ?14 | 0 | 93,233 | 0.02 | ||
| Pantropical spotted dolphin | Western North Atlantic | 114 | 0 | 114 | 0 | 6,593 | 1.73 | ||
| Atlantic spotted dolphin | Western North Atlantic | 1,232 | 5 | 1,237 | 0 | 39,921 | 3.1 | ||
| Spinner dolphin | Western North Atlantic | 41 | 0 | 41 | 0 | 4,102 | 1.00 | ||
| Clymene dolphin | Western North Atlantic | 79 | 0 | 79 | 0 | 4,237 | 1.87 | ||
| Striped dolphin | Western North Atlantic | 19 | 0 | 1 ?45 | 0 | 67,036 | 0.07 | ||
| Fraser's dolphin | Western North Atlantic | 62 | 0 | 2 ?163 | 0 | unk | |||
| Risso's dolphin | Western North Atlantic | 189 | 0 | 189 | 0 | 35,215 | 0.54 | ||
| Common dolphin | Western North Atlantic | 56 | 0 | 56 | 0 | 172,947 | 11.99 | ||
| Melon-headed whale | Western North Atlantic | 58 | 0 | 2 ?83 | 0 | 3,965 | 2.15 | ||
| Pygmy killer whale | Western North Atlantic | 6 | 0 | 6 | 0 | unk | |||
| False killer whale | Western North Atlantic | 1 | 0 | 2 ?6 | 0 | 1,791 | 0.34 | ||
| Killer whale | Western North Atlantic | 2 | 0 | 1 ?4 | 0 | unk | |||
| Harbor porpoise | Gulf of Maine/Bay of Fundy | 0.01 | 0 | 1 ?3 | 0 | 95,543 | 0.00 | ||
| 1 ?Take increased to mean group size from the Atlantic Marine Assessment Program for Protected Species (AMAPPS; Palka et al., 2017 and 2021). | |||||||||
| 2 ?Take increased to mean group size from the Ocean Biodiversity Information System (OBIS 2023). | |||||||||
Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to the activity, and other means of effecting the least practicable impact on the species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stock for taking for certain subsistence uses (latter not applicable for this action). NMFS regulations require applicants for incidental take authorizations to include information about the availability and feasibility (economic and technological) of equipment, methods, and manner of conducting the activity or other means of effecting the least practicable adverse impact upon the affected species or stocks, and their habitat (50 CFR 216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to ensure the least practicable adverse impact on species or stocks and their habitat, as well as subsistence uses where applicable, NMFS considers two primary factors:
(1) The manner in which, and the degree to which, the successful implementation of the measure(s) is expected to reduce impacts to marine mammals, marine mammal species or stocks, and their habitat, as well as subsistence uses. This considers the nature of the potential adverse impact being mitigated (likelihood, scope, range). It further considers the likelihood that the measure will be effective if implemented (probability of accomplishing the mitigating result if implemented as planned), the likelihood of effective implementation (probability implemented as planned); and
(2) The practicability of the measures for applicant implementation, which may consider such things as cost, and impact on operations.
Vessel-Based Visual Mitigation Monitoring
[top] Visual monitoring requires the use of trained observers (herein referred to as visual protected species observers (PSO)) to scan the ocean surface for the presence of marine mammals. The area to be scanned visually includes primarily the shutdown zone (SZ), within which observation of certain marine mammals requires shutdown of the acoustic source, but also a buffer zone and, to the extent possible depending on conditions, the surrounding waters. The buffer zone means an area beyond the SZ to be monitored for the presence of marine mammals that may enter the SZ. During pre-start clearance monitoring ( i.e., before ramp-up begins), the buffer zone
L-DEO must use dedicated, trained, NMFS-approved PSOs. The PSOs must have no tasks other than to conduct observational effort, record observational data, and communicate with and instruct relevant vessel crew with regard to the presence of marine mammals and mitigation requirements. PSO resumes shall be provided to NMFS for approval.
At least one of the visual and two of the acoustic PSOs (discussed below) aboard the vessel must have a minimum of 90 days at-sea experience working in those roles, respectively, with no more than 18 months elapsed since the conclusion of the at-sea experience. One visual PSO with such experience shall be designated as the lead for the entire protected species observation team. The lead PSO shall serve as primary point of contact for the vessel operator and ensure all PSO requirements per the IHA are met. To the maximum extent practicable, the experienced PSOs should be scheduled to be on duty with those PSOs with appropriate training but who have not yet gained relevant experience.
During survey operations ( e.g., any day on which use of the acoustic source is planned to occur, and whenever the acoustic source is in the water, whether activated or not), a minimum of two visual PSOs must be on duty and conducting visual observations at all times during daylight hours ( i.e., from 30 minutes prior to sunrise through 30 minutes following sunset). Visual monitoring of the pre-start clearance zone must begin no less than 30 minutes prior to ramp-up, and monitoring must continue until 1 hour after use of the acoustic source ceases or until 30 minutes past sunset. Visual PSOs shall coordinate to ensure 360° visual coverage around the vessel from the most appropriate observation posts, and shall conduct visual observations using binoculars and the naked eye while free from distractions and in a consistent, systematic, and diligent manner.
PSOs shall establish and monitor the shutdown and buffer zones. These zones shall be based upon the radial distance from the edges of the acoustic source (rather than being based on the center of the array or around the vessel itself). During use of the acoustic source ( i.e., anytime airguns are active, including ramp-up), detections of marine mammals within the buffer zone (but outside the SZ) shall be communicated to the operator to prepare for the potential shutdown of the acoustic source. Visual PSOs will immediately communicate all observations to the on duty acoustic PSO(s), including any determination by the PSO regarding species identification, distance, and bearing and the degree of confidence in the determination. Any observations of marine mammals by crew members shall be relayed to the PSO team. During good conditions ( e.g., daylight hours; Beaufort sea state (BSS) 3 or less), visual PSOs shall conduct observations when the acoustic source is not operating for comparison of sighting rates and behavior with and without use of the acoustic source and between acquisition periods, to the maximum extent practicable.
Visual PSOs may be on watch for a maximum of 4 consecutive hours followed by a break of at least 1 hour between watches and may conduct a maximum of 12 hours of observation per 24-hour period. Combined observational duties (visual and acoustic but not at same time) may not exceed 12 hours per 24-hour period for any individual PSO.
Passive Acoustic Monitoring (PAM)
Acoustic monitoring means the use of trained personnel (sometimes referred to as PAM operators, herein referred to as acoustic PSOs) to operate PAM equipment to acoustically detect the presence of marine mammals. Acoustic monitoring involves acoustically detecting marine mammals regardless of distance from the source, as localization of animals may not always be possible. Acoustic monitoring is intended to further support visual monitoring (during daylight hours) in maintaining an SZ around the sound source that is clear of marine mammals. In cases where visual monitoring is not effective ( e.g., due to weather, nighttime), acoustic monitoring may be used to allow certain activities to occur, as further detailed below.
PAM will take place in addition to the visual monitoring program. Visual monitoring typically is not effective during periods of poor visibility or at night, and even with good visibility, is unable to detect marine mammals when they are below the surface or beyond visual range. Acoustic monitoring can be used in addition to visual observations to improve detection, identification, and localization of cetaceans. The acoustic monitoring will serve to alert visual PSOs (if on duty) when vocalizing cetaceans are detected. It is only useful when marine mammals vocalize, but it can be effective either by day or by night, and does not depend on good visibility. It will be monitored in real time so that the visual observers can be advised when cetaceans are detected.
The R/V Langseth will use a towed PAM system, which must be monitored by at a minimum one on duty acoustic PSO beginning at least 30 minutes prior to ramp-up and at all times during use of the acoustic source. Acoustic PSOs may be on watch for a maximum of 4 consecutive hours followed by a break of at least 1 hour between watches and may conduct a maximum of 12 hours of observation per 24-hour period. Combined observational duties (acoustic and visual but not at same time) may not exceed 12 hours per 24-hour period for any individual PSO.
Survey activity may continue for 30 minutes when the PAM system malfunctions or is damaged, while the PAM operator diagnoses the issue. If the diagnosis indicates that the PAM system must be repaired to solve the problem, operations may continue for an additional 5 hours without acoustic monitoring during daylight hours only under the following conditions:
• Sea state is less than or equal to BSS 4;
• No marine mammals (excluding delphinids) detected solely by PAM in the applicable EZ in the previous 2 hours;
• NMFS is notified via email as soon as practicable with the time and location in which operations began occurring without an active PAM system; and
[top] • Operations with an active acoustic source, but without an operating PAM system, do not exceed a cumulative total of 5 hours in any 24-hour period.
Establishment of Shutdown and Pre-Start Clearance Zones
An SZ is a defined area within which occurrence of a marine mammal triggers mitigation action intended to reduce the potential for certain outcomes, e.g., auditory injury, disruption of critical behaviors. The PSOs will establish a minimum SZ with a 500-m radius. The 500-m SZ will be based on radial distance from the edge of the airgun array (rather than being based on the center of the array or around the vessel itself). With certain exceptions (described below), if a marine mammal appears within or enters this zone, the acoustic source will be shut down.
The pre-start clearance zone is defined as the area that must be clear of marine mammals prior to beginning ramp-up of the acoustic source, and includes the SZ plus the buffer zone. Detections of marine mammals within the pre-start clearance zone will prevent airgun operations from beginning ( i.e., ramp-up).
The 500-m SZ is intended to be precautionary in the sense that it will be expected to contain sound exceeding the injury criteria for all cetacean hearing groups, (based on the dual criteria of SEL cum and peak SPL), while also providing a consistent, reasonably observable zone within which PSOs will typically be able to conduct effective observational effort. Additionally, a 500-m SZ is expected to minimize the likelihood that marine mammals will be exposed to levels likely to result in more severe behavioral responses. Although significantly greater distances may be observed from an elevated platform under good conditions, we believe that 500 m is likely regularly attainable for PSOs using the naked eye during typical conditions. The pre-start clearance zone simply represents the addition of a buffer to the SZ, doubling the SZ size during pre-clearance.
An extended SZ of 1,500 m must be enforced for all beaked whales and Kogia species. No buffer of this extended SZ is required.
Pre-Start Clearance and Ramp-Up
Ramp-up (sometimes referred to as "soft start") means the gradual and systematic increase of emitted sound levels from an airgun array. Ramp-up begins by first activating a single airgun of the smallest volume, followed by doubling the number of active elements in stages until the full complement of an array's airguns are active. Each stage should be approximately the same duration, and the total duration should not be less than approximately 20 minutes. The intent of pre-start clearance observation (30 minutes) is to ensure no protected species are observed within the pre-clearance zone (or extended SZ, for beaked whales and Kogia spp.) prior to the beginning of ramp-up. During pre-start clearance period is the only time observations of marine mammals in the buffer zone will prevent operations ( i.e., the beginning of ramp-up). The intent of ramp-up is to warn marine mammals of pending seismic survey operations and to allow sufficient time for those animals to leave the immediate vicinity prior to the sound source reaching full intensity. A ramp-up procedure, involving a step-wise increase in the number of airguns firing and total array volume until all operational airguns are activated and the full volume is achieved, is required at all times as part of the activation of the acoustic source. All operators must adhere to the following pre-start clearance and ramp-up requirements:
• The operator must notify a designated PSO of the planned start of ramp-up as agreed upon with the lead PSO; the notification time should not be less than 60 minutes prior to the planned ramp-up in order to allow the PSOs time to monitor the pre-start clearance zone (and extended SZ) for 30 minutes prior to the initiation of ramp-up (pre-start clearance);
• Ramp-ups shall be scheduled so as to minimize the time spent with the source activated prior to reaching the designated run-in;
• One of the PSOs conducting pre-start clearance observations must be notified again immediately prior to initiating ramp-up procedures and the operator must receive confirmation from the PSO to proceed;
• Ramp-up may not be initiated if any marine mammal is within the applicable shutdown or buffer zone. If a marine mammal is observed within the pre-start clearance zone (or extended SZ, for beaked whales and Kogia species) during the 30 minute pre-start clearance period, ramp-up may not begin until the animal(s) has been observed exiting the zones or until an additional time period has elapsed with no further sightings (15 minutes for small odontocetes, and 30 minutes for all mysticetes and all other odontocetes, including sperm whales, beaked whales, and large delphinids, such as pilot whales);
• Ramp-up shall begin by activating a single airgun of the smallest volume in the array and shall continue in stages by doubling the number of active elements at the commencement of each stage, with each stage of approximately the same duration. Duration shall not be less than 20 minutes. The operator must provide information to the PSO documenting that appropriate procedures were followed;
• PSOs must monitor the pre-start clearance zone (and extended SZ) during ramp-up, and ramp-up must cease and the source must be shut down upon detection of a marine mammal within the applicable zone. Once ramp-up has begun, detections of marine mammals within the buffer zone do not require shutdown, but such observation shall be communicated to the operator to prepare for the potential shutdown;
• Ramp-up may occur at times of poor visibility, including nighttime, if appropriate acoustic monitoring has occurred with no detections in the 30 minutes prior to beginning ramp-up. Acoustic source activation may only occur at times of poor visibility where operational planning cannot reasonably avoid such circumstances;
• If the acoustic source is shut down for brief periods ( i.e., less than 30 minutes) for reasons other than that described for shutdown ( e.g., mechanical difficulty), it may be activated again without ramp-up if PSOs have maintained constant visual and/or acoustic observation and no visual or acoustic detections of marine mammals have occurred within the applicable SZ. For any longer shutdown, pre-start clearance observation and ramp-up are required. For any shutdown at night or in periods of poor visibility ( e.g., BSS 4 or greater), ramp-up is required, but if the shutdown period was brief and constant observation was maintained, pre-start clearance watch of 30 minutes is not required; and
• Testing of the acoustic source involving all elements requires ramp-up. Testing limited to individual source elements or strings does not require ramp-up but does require pre-start clearance of 30 min.
Shutdown
[top] The shutdown of an airgun array requires the immediate de-activation of all individual airgun elements of the array. Any PSO on duty will have the authority to delay the start of survey operations or to call for shutdown of the acoustic source if a marine mammal is detected within the applicable SZ. The operator must also establish and maintain clear lines of communication directly between PSOs on duty and crew controlling the acoustic source to ensure that shutdown commands are conveyed swiftly while allowing PSOs to maintain watch. When both visual and acoustic PSOs are on duty, all detections will be immediately communicated to the remainder of the on-duty PSO team for potential verification of visual observations by the
Following a shutdown, airgun activity will not resume until the marine mammal has cleared the SZ. The animal will be considered to have cleared the SZ if it is visually observed to have departed the SZ ( i.e., animal is not required to fully exit the buffer zone where applicable), or it has not been seen within the SZ for 15 minutes for small odontocetes, or 30 minutes for all mysticetes and all other odontocetes, including sperm whales, beaked whales, Kogia species, and large delphinids, such as pilot whales.
The shutdown requirement is waived for small dolphins if an individual is detected within the SZ. As defined here, the small dolphin group is intended to encompass those members of the Family Delphinidae most likely to voluntarily approach the source vessel for purposes of interacting with the vessel and/or airgun array ( e.g., bow riding). This exception to the shutdown requirement applies solely to specific genera of small dolphins ( Delphinus, Lagenodelphis, Stenella, Steno, and Tursiops ).
We include this small dolphin exception because shutdown requirements for small dolphins under all circumstances represent practicability concerns without likely commensurate benefits for the animals in question. Small dolphins are generally the most commonly observed marine mammals in the specific geographic region and will 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 dolphins commonly approach vessels and/or towed arrays during active sound production for purposes of bow riding, with no apparent effect observed in those delphinoids ( e.g., Barkaszi et al., 2012, Barkaszi and Kelly, 2018). The potential for increased shutdowns resulting from such a measure will require the Langseth to revisit the missed track line to reacquire data, resulting in an overall increase in the total sound energy input to the marine environment and an increase in the total duration over which the survey is active in a given area. Although other mid-frequency hearing specialists ( e.g., large delphinids) are no more likely to incur auditory injury than are small dolphins, they are much less likely to approach vessels. Therefore, retaining a shutdown requirement for large delphinids will not have similar impacts in terms of either practicability for the applicant or corollary increase in sound energy output and time on the water. We do anticipate some benefit for a shutdown requirement for large delphinids in that it simplifies somewhat the total range of decision-making for PSOs and may preclude any potential for physiological effects other than to the auditory system as well as some more severe behavioral reactions for any such animals in close proximity to the Langseth.
Visual PSOs shall use best professional judgment in making the decision to call for a shutdown if there is uncertainty regarding identification ( i.e., whether the observed marine mammal(s) belongs to one of the delphinid genera for which shutdown is waived or one of the species with a larger SZ).
L-DEO must implement shutdown if a marine mammal species for which take was not authorized, or a species for which authorization was granted but the takes have been met, approaches the Level A or Level B harassment zones. L-DEO must also implement shutdown if any large whale (defined as a sperm whale or any mysticete species) with a calf (defined as an animal less than two-thirds the body size of an adult observed to be in close association with an adult) and/or an aggregation of six or more large whales are observed at any distance. Finally, L-DEO must implement shutdown upon detection (visual or acoustic) of a North Atlantic right whale at any distance.
Vessel Strike Avoidance
Vessel operators and crews must maintain a vigilant watch for all protected species and slow down, stop their vessel, or alter course, as appropriate and regardless of vessel size, to avoid striking any marine mammal. A visual observer aboard the vessel must monitor a vessel strike avoidance zone around the vessel (distances stated below). Visual observers monitoring the vessel strike avoidance zone may be third-party observers ( i.e., PSOs) or crew members, but crew members responsible for these duties must be provided sufficient training to (1) distinguish marine mammals from other phenomena, and (2) broadly identify a marine mammal as a whale or other marine mammal.
Vessel speeds must be reduced to 10 kn or less when mother/calf pairs, pods, or large assemblages of cetaceans are observed near a vessel.
All vessels must maintain a minimum separation distance of 500 m from North Atlantic right whales and 100 m from sperm whales and all other baleen whales.
All vessels must, to the maximum extent practicable, attempt to maintain a minimum separation distance of 50 m from all other marine mammals, with an understanding that at times this may not be possible ( e.g., for animals that approach the vessel).
When marine mammals are sighted while a vessel is underway, the vessel shall take action as necessary to avoid violating the relevant separation distance ( e.g., attempt to remain parallel to the animal's course, avoid excessive speed or abrupt changes in direction until the animal has left the area). If marine mammals are sighted within the relevant separation distance, the vessel must reduce speed and shift the engine to neutral, not engaging the engines until animals are clear of the area. This does not apply to any vessel towing gear or any vessel that is navigationally constrained.
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.
[top] All survey vessels, regardless of size, must observe a 10-kn speed restriction in specific areas designated by NMFS for the protection of North Atlantic right whales from vessel strikes. These include all Seasonal Management Areas (SMA) established under 50 CFR 224.105 (when in effect), any dynamic management areas (DMA) (when in effect), and Slow Zones. See www.fisheries.noaa.gov/national/endangered-species-conservation/reducing-ship-strikes-north-atlantic-
Operational Restrictions
L-DEO must limit airgun use to between May 1 and October 31. Vessel movement and other activities that do not require use of airguns may occur outside of these dates. If any activities (non-seismic) are conducted between November 1 and April 30, daily PSO logs must be sent to the NOAA Southeast Regional Office (SERO). L-DEO must also notify SERO on the start and end date of seismic operations in the survey area via email ( nmfs.ser.research.notification@noaa.gov ).
Based on our evaluation of the applicant's measures, as well as other measures considered by NMFS, NMFS has determined that the mitigation measures provide the means of effecting the least practicable impact on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance.
Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of the MMPA states that NMFS must set forth requirements pertaining to the monitoring and reporting of such taking. The MMPA implementing regulations at 50 CFR 216.104(a)(13) indicate that requests for authorizations must include the suggested means of accomplishing the necessary monitoring and reporting that will result in increased knowledge of the species and of the level of taking or impacts on populations of marine mammals that are expected to be present while conducting the activities. Effective reporting is critical both to compliance as well as ensuring that the most value is obtained from the required monitoring.
Monitoring and reporting requirements prescribed by NMFS should contribute to improved understanding of one or more of the following:
• Occurrence of marine mammal species or stocks in the area in which take is anticipated ( e.g., presence, abundance, distribution, density);
• Nature, scope, or context of likely marine mammal exposure to potential stressors/impacts (individual or cumulative, acute or chronic), through better understanding of: (1) action or environment ( e.g., source characterization, propagation, ambient noise); (2) affected species ( e.g., life history, dive patterns); (3) co-occurrence of marine mammal species with the activity; or (4) biological or behavioral context of exposure ( e.g., age, calving or feeding areas);
• Individual marine mammal responses (behavioral or physiological) to acoustic stressors (acute, chronic, or cumulative), other stressors, or cumulative impacts from multiple stressors;
• How anticipated responses to stressors impact either: (1) long-term fitness and survival of individual marine mammals; or (2) populations, species, or stocks;
• Effects on marine mammal habitat ( e.g., marine mammal prey species, acoustic habitat, or other important physical components of marine mammal habitat); and,
• Mitigation and monitoring effectiveness.
Vessel-Based Visual Monitoring
As described above, PSO observations will take place during daytime airgun operations. During seismic survey operations, at least five visual PSOs will be based aboard the Langseth. Two visual PSOs will be on duty at all times during daytime hours. Monitoring shall be conducted in accordance with the following requirements:
• The operator shall provide PSOs with bigeye binoculars ( e.g., 25 x 150; 2.7 view angle; individual ocular focus; height control) of appropriate quality ( i.e., Fujinon or equivalent) solely for PSO use. These shall be pedestal-mounted on the deck at the most appropriate vantage point that provides for optimal sea surface observation, PSO safety, and safe operation of the vessel; and
• The operator will work with the selected third-party observer provider to ensure PSOs have all equipment (including backup equipment) needed to adequately perform necessary tasks, including accurate determination of distance and bearing to observed marine mammals.
PSOs must have the following requirements and qualifications:
• PSOs shall be independent, dedicated, trained visual and acoustic PSOs and must be employed by a third-party observer provider;
• PSOs shall have no tasks other than to conduct observational effort (visual or acoustic), collect data, and communicate with and instruct relevant vessel crew with regard to the presence of protected species and mitigation requirements (including brief alerts regarding maritime hazards);
• PSOs shall have successfully completed an approved PSO training course appropriate for their designated task (visual or acoustic). Acoustic PSOs are required to complete specialized training for operating PAM systems and are encouraged to have familiarity with the vessel with which they will be working;
• PSOs can act as acoustic or visual observers (but not at the same time) as long as they demonstrate that their training and experience are sufficient to perform the task at hand;
• NMFS must review and approve PSO resumes accompanied by a relevant training course information packet that includes the name and qualifications ( i.e., experience, training completed, or educational background) of the instructor(s), the course outline or syllabus, and course reference material as well as a document stating successful completion of the course;
• PSOs must successfully complete relevant training, including completion of all required coursework and passing (80 percent or greater) a written and/or oral examination developed for the training program;
• PSOs must have successfully attained a bachelor's degree from an accredited college or university with a major in one of the natural sciences, a minimum of 30 semester hours or equivalent in the biological sciences, and at least one undergraduate course in math or statistics; and
• The educational requirements may be waived if the PSO has acquired the relevant skills through alternate experience. Requests for such a waiver shall be submitted to NMFS and must include written justification. Requests shall be granted or denied (with justification) by NMFS within 1 week of receipt of submitted information. Alternate experience that may be considered includes, but is not limited to (1) secondary education and/or experience comparable to PSO duties; (2) previous work experience conducting academic, commercial, or government-sponsored protected species surveys; or (3) previous work experience as a PSO; the PSO should demonstrate good standing and consistently good performance of PSO duties.
[top] For data collection purposes, PSOs shall use standardized data collection forms, whether hard copy or electronic. PSOs shall 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
• Vessel names (source vessel and other vessels associated with survey) and call signs;
• PSO names and affiliations;
• Dates of departures and returns to port with port name;
• Date and participants of PSO briefings;
• Dates and times (Greenwich Mean Time) of survey effort and times corresponding with PSO effort;
• Vessel location (latitude/longitude) when survey effort began and ended and vessel location at beginning and end of visual PSO duty shifts;
• Vessel heading and speed at beginning and end of visual PSO duty shifts and upon any line change;
• 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;
• 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
• 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-start clearance, ramp-up, shutdown, testing, shooting, ramp-up completion, end of operations, streamers, etc. ).
The following information should be recorded upon visual observation of any protected species:
• Watch status (sighting made by PSO on/off effort, opportunistic, crew, alternate vessel/platform);
• PSO who sighted the animal;
• Time of sighting;
• Vessel location at time of sighting;
• Water depth;
• Direction of vessel's travel (compass direction);
• Direction of animal's travel relative to the vessel;
• Pace of the animal;
• Estimated distance to the animal and its heading relative to vessel at initial sighting;
• 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;
• Estimated number of animals (high/low/best);
• Estimated number of animals by cohort (adults, yearlings, juveniles, calves, group composition, etc. );
• 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);
• 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);
• Animal's closest point of approach (CPA) and/or closest distance from any element of the acoustic source;
• Platform activity at time of sighting ( e.g., deploying, recovering, testing, shooting, data acquisition, other); and
• Description of any actions implemented in response to the sighting ( e.g., delays, shutdown, ramp-up) and time and location of the action.
If a marine mammal is detected while using the PAM system, the following information should be recorded:
• An acoustic encounter identification number, and whether the detection was linked with a visual sighting;
• Date and time when first and last heard;
• Types and nature of sounds heard ( e.g., clicks, whistles, creaks, burst pulses, continuous, sporadic, strength of signal); and
• Any additional information recorded, such as water depth of the hydrophone array, bearing of the animal to the vessel (if determinable), species or taxonomic group (if determinable), spectrogram screenshot, and any other notable information.
Reporting
L-DEO must submit a draft comprehensive report to NMFS on all activities and monitoring results within 90 days of the completion of the survey or expiration of the IHA, whichever comes sooner. A final report must be submitted within 30 days following resolution of any comments on the draft report. The report will describe the operations that were conducted and sightings of marine mammals near the operations. The report will provide full documentation of methods, results, and interpretation pertaining to all monitoring. The 90-day report will summarize the dates and locations of seismic operations, and all marine mammal sightings (dates, times, locations, activities, associated seismic survey activities). The report will also include estimates of the number and nature of exposures that occurred above the harassment threshold based on PSO observations and including an estimate of those that were not detected, in consideration of both the characteristics and behaviors of the species of marine mammals that affect detectability, as well as the environmental factors that affect detectability.
The draft report shall also include geo-referenced time-stamped vessel tracklines for all time periods during which airguns were operating. Tracklines should 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). Geographic Information Systems (GIS) files shall be provided in Environmental Systems Research Institute (ESRI) shapefile format and include the UTC date and time, latitude in decimal degrees, and longitude in decimal degrees. All coordinates shall be referenced to the WGS84 geographic coordinate system. In addition to the report, all raw observational data shall be made available to NMFS. A final report must be submitted within 30 days following resolution of any comments on the draft report.
Reporting Species of Concern
Although not anticipated, if a North Atlantic right whale is observed at any time by PSOs or personnel on any project vessels, during surveys or during vessel transit, L-DEO must immediately report sighting information to the NMFS North Atlantic Right Whale Sighting Advisory System: 877-WHALE-HELP (877-942-5343). North Atlantic right whale sightings in any location must also be reported to the U.S. Coast Guard via channel 16.
Reporting Injured or Dead Marine Mammals
Discovery of injured or dead marine mammals -In the event that personnel involved in survey activities covered by the authorization discover an injured or dead marine mammal, the L-DEO shall report the incident to the Office of Protected Resources (OPR), NMFS and to the NMFS South East Regional Stranding Coordinator as soon as feasible. The report must include the following information:
• Time, date, and location (latitude/longitude) of the first discovery (and updated location information if known and applicable);
• Species identification (if known) or description of the animal(s) involved;
[top] • Condition of the animal(s) (including carcass condition if the animal is dead);
• Observed behaviors of the animal(s), if alive;
• If available, photographs or video footage of the animal(s); and
• 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, L-DEO shall report the incident to OPR, NMFS and to the NMFS South East Regional Stranding Coordinator as soon as feasible. The report must include the following information:
• Time, date, and location (latitude/longitude) of the incident;
• Vessel's speed during and leading up to the incident;
• Vessel's course/heading and what operations were being conducted (if applicable);
• Status of all sound sources in use;
• 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;
• Environmental conditions ( e.g., wind speed and direction, Beaufort sea state, cloud cover, visibility) immediately preceding the strike;
• Species identification (if known) or description of the animal(s) involved;
• Estimated size and length of the animal that was struck;
• Description of the behavior of the animal immediately preceding and following the strike;
• If available, description of the presence and behavior of any other marine mammals present immediately preceding the strike;
• 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
• To the extent practicable, photographs or video footage of the animal(s).
Actions To Minimize Additional Harm to Live-Stranded (or Milling) Marine Mammals
In the event of a live stranding (or near-shore atypical milling) event within 50 km of the survey operations, where the NMFS stranding network is engaged in herding or other interventions to return animals to the water, the Director of OPR, NMFS (or designee) will advise L-DEO of the need to implement shutdown procedures for all active acoustic sources operating within 50 km of the stranding. Shutdown procedures for live stranding or milling marine mammals include the following: If at any time, the marine mammal the marine mammal(s) die or are euthanized, or if herding/intervention efforts are stopped, the Director of OPR, NMFS (or designee) will advise the IHA-holder that the shutdown around the animals' location is no longer needed. Otherwise, shutdown procedures will remain in effect until the Director of OPR, NMFS (or designee) determines and advises L-DEO that all live animals involved have left the area (either of their own volition or following an intervention).
If further observations of the marine mammals indicate the potential for re-stranding, additional coordination with the IHA-holder will be required to determine what measures are necessary to minimize that likelihood ( e.g., extending the shutdown or moving operations farther away) and to implement those measures as appropriate.
Additional Information Requests -if NMFS determines that the circumstances of any marine mammal stranding found in the vicinity of the activity suggest investigation of the association with survey activities is warranted, and an investigation into the stranding is being pursued, NMFS will submit a written request to L-DEO indicating that the following initial available information must be provided as soon as possible, but no later than 7 business days after the request for information:
• Status of all sound source use in the 48 hours preceding the estimated time of stranding and within 50 km of the discovery/notification of the stranding by NMFS; and
• If available, description of the behavior of any marine mammal(s) observed preceding ( i.e., within 48 hours and 50 km) and immediately after the discovery of the stranding.
In the event that the investigation is still inconclusive, the investigation of the association of the survey activities is still warranted, and the investigation is still being pursued, NMFS may provide additional information requests, in writing, regarding the nature and location of survey operations prior to the time period above.
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival (50 CFR 216.103). A negligible impact finding is based on the lack of likely adverse effects on annual rates of recruitment or survival ( i.e., population-level effects). An estimate of the number of takes alone is not enough information on which to base an impact determination. In addition to considering estimates of the number of marine mammals that might be "taken" through harassment, NMFS considers other factors, such as the likely nature of any impacts or responses ( e.g., intensity, duration), the context of any impacts or responses ( e.g., critical reproductive time or location, foraging impacts affecting energetics), as well as effects on habitat, and the likely effectiveness of the mitigation. We also assess the number, intensity, and context of estimated takes by evaluating this information relative to population status. Consistent with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, September 29, 1989), the impacts from other past and ongoing anthropogenic activities are incorporated into this analysis via their impacts on the baseline ( e.g., as reflected in the regulatory status of the species, population size and growth rate where known, ongoing sources of human-caused mortality, or ambient noise levels).
To avoid repetition, the discussion of our analysis applies to all the species listed in Table 1, given that the anticipated effects of this activity on these different marine mammal stocks are expected to be similar. Where there are meaningful differences between species or stocks they are included as separate subsections below. NMFS does not anticipate that serious injury or mortality will occur as a result of L-DEO's planned survey, even in the absence of mitigation, and no serious injury or mortality is authorized. As discussed in the Potential Effects of Specified Activities on Marine Mammals and Their Habitat section above, non-auditory physical effects and vessel strike are not expected to occur. NMFS expects that the majority potential takes will be in the form of short-term Level B behavioral harassment in the form of temporary avoidance of the area or decreased foraging (if such activity was occurring), reactions that are considered to be of low severity and with no lasting biological consequences ( e.g., Southall et al., 2007). Even repeated Level B harassment of some small subset of an overall stock is unlikely to result in any significant realized decrease in viability for the affected individuals, and thus will not result in any adverse impact to the stock as a whole.
[top] We authorized a limited number of instances of Level A harassment of two species (pygmy and dwarf sperm
In addition to being temporary, the maximum expected Level B harassment zone around the survey vessel is 2,886 m for water depths greater than 1,000 m (and up to 4,329 m in water depths of 100 to 1,000 m). Therefore, the ensonified area surrounding the vessel is relatively small compared to the overall distribution of animals in the area and their use of the habitat. Feeding behavior is not likely to be significantly impacted as prey species are mobile and are broadly distributed throughout the survey area; therefore, marine mammals that may be temporarily displaced during survey activities are expected to be able to resume foraging once they have moved away from areas with disturbing levels of underwater noise. Because of the short duration (28 days) and temporary nature of the disturbance and the availability of similar habitat and resources in the surrounding area, the impacts to marine mammals and the food sources that they utilize are not expected to cause significant or long-term consequences for individual marine mammals or their populations.
There are no rookeries, mating or calving grounds known to be biologically important to marine mammals within the survey area and there are no feeding areas known to be biologically important to marine mammals within the survey area. There is no designated critical habitat for any ESA-listed marine mammals in the survey area.
Marine Mammal Species With Active Unusual Mortality Events UMEs
As discussed above, there are several active UMEs occurring in the vicinity of L-DEO's survey area. Elevated humpback whale mortalities have occurred along the Atlantic coast from Maine through Florida since January 2016. Of the cases examined, approximately half had evidence of human interaction (ship strike or entanglement). The UME does not yet provide cause for concern regarding population-level impacts. Despite the UME, the relevant population of humpback whales (the West Indies breeding population, or DPS) remains stable at approximately 12,000 individuals.
Beginning in January 2017, elevated minke whale strandings have occurred along the Atlantic coast from Maine through South Carolina, with highest numbers in Massachusetts, Maine, and New York. This event does not provide cause for concern regarding population level impacts, as the likely population abundance is greater than 20,000 whales.
The mitigation measures are expected to reduce the number and/or severity of takes for all species listed in Table 1, including those with active UMEs, to the level of least practicable adverse impact. In particular they will provide animals the opportunity to move away from the sound source throughout the survey area before seismic survey equipment reaches full energy, thus preventing them from being exposed to sound levels that have the potential to cause injury (Level A harassment) or more severe Level B harassment. No Level A harassment is anticipated, even in the absence of mitigation measures, or authorized for species with active UMEs.
In summary and as described above, the following factors primarily support our determination that the impacts resulting from this activity are not expected to adversely affect any of the species or stocks through effects on annual rates of recruitment or survival:
• No serious injury or mortality is anticipated or authorized;
• The activity is temporary and of relatively short duration (28 days);
• The anticipated impacts of the activity on marine mammals will be temporary behavioral changes due to avoidance of the area around the vessel;
• The availability of alternative areas of similar habitat value for marine mammals to temporarily vacate the survey area during the survey to avoid exposure to sounds from the activity is readily abundant;
• The potential adverse effects on fish or invertebrate species that serve as prey species for marine mammals from the survey will be temporary and spatially limited, and impacts to marine mammal foraging will be minimal;
• The mitigation measures are expected to reduce the number of takes by Level A harassment (in the form of PTS) by allowing for detection of marine mammals in the vicinity of the vessel by visual and acoustic observers; and
• The mitigation measures, including visual and acoustic shutdowns are expected to minimize potential impacts to marine mammals (both amount and severity).
Based on the analysis contained herein of the likely effects of the specified activity on marine mammals and their habitat, and taking into consideration the implementation of the monitoring and mitigation measures, NMFS finds that the total marine mammal take from the activity will have a negligible impact on all affected marine mammal species or stocks.
Small Numbers
[top] As noted previously, 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
The amount of take NMFS authorized is below one third of the estimated stock abundance for all species with available abundance estimates (in fact, take of individuals is less than fifteen percent of the abundance of the affected stocks, see Table 6). This is likely a conservative estimate because we assume all takes are of different individual animals, which is likely not the case. Some individuals may be encountered multiple times in a day, but PSOs will count them as separate individuals if they cannot be identified.
NMFS considers it appropriate to make a small numbers finding in the case of a species or stock that may potentially be taken but is either rarely encountered or only expected to be taken on rare occasions. In that circumstance, one or two assumed encounters with a group of animals (meaning a group that is traveling together or aggregated, and thus exposed to a stressor at the same approximate time) should reasonably be considered small numbers, regardless of consideration of the proportion of the stock (if known), as rare encounters resulting in take of one or two groups should be considered small relative to the range and distribution of any stock. In this case, NMFS authorized take resulting from a single exposure of one group each for Fraser's dolphin and killer whale (using average group size), and find that a single incident of take of one group of either of these species represents take of small numbers for that species.
For pygmy killer whale, we authorized six incidents of take by Level B harassment. No abundance information is available for this species in the survey area. Therefore, we refer to other SAR abundance estimates for the species. NMFS estimates that the Hawaii stock of pygmy killer whales has a minimum abundance estimate of 5,885 whales (Carretta et al., 2020). In the Gulf of Mexico, NMFS estimates a minimum abundance of 613 whales for that stock (Hayes et al., 2020). Therefore, NMFS assumes that the estimated take number of six would be small relative to any reasonable estimate of population abundance for the species in the Atlantic.
Based on the analysis contained herein of the activity (including the mitigation and monitoring measures) and the anticipated take of marine mammals, NMFS finds that small numbers of marine mammals would be taken relative to the population size of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine mammal stocks or species implicated by this action. Therefore, NMFS has determined that the total taking of affected species or stocks will not have an unmitigable adverse impact on the availability of such species or stocks for taking for subsistence purposes.
Endangered Species Act
Section 7(a)(2) of the Endangered Species Act of 1973 (ESA; 16 U.S.C. 1531 et seq. ) requires that each Federal agency insure that any action it authorizes, funds, or carries out is not likely to jeopardize the continued existence of any endangered or threatened species or result in the destruction or adverse modification of designated critical habitat. To ensure ESA compliance for the issuance of IHAs, NMFS consults internally whenever we propose to authorize take for endangered or threatened species, in this case with the ESA Interagency Cooperation Division within NMFS' Office of Protected Resources (OPR).
The NMFS Office of Protected Resources ESA Interagency Cooperation Division issued a Biological Opinion under section 7 of the ESA, on the issuance of an IHA to L-DEO under section 101(a)(5)(D) of the MMPA by the NMFS OPR Permits and Conservation Division. The Biological Opinion concluded that the action is not likely to jeopardize the continued existence of ESA-listed North Atlantic right whales, blue whales, fin whales, sei whales, and sperm whales.
National Environmental Policy Act
In compliance with the National Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq. ), as implemented by the regulations published by the Council on Environmental Quality (40 CFR parts 1500-1508), the National Science Foundation prepared an Environmental Analysis (EA) to consider the direct, indirect, and cumulative effects to the human environment from the planned marine geophysical survey off of North Carolina. NSF's EA was made available to the public for review and comment in relation to its suitability for adoption by NMFS in order to assess the impacts to the human environment of issuance of an IHA to L-DEO. In compliance with NEPA and the CEQ regulations, as well as NOAA Administrative Order 216-6, NMFS has reviewed the NSF's EA, determined it to be sufficient, and adopted that EA and signed a Finding of No Significant Impact (FONSI). NSF's EA is available at https://www.nsf.gov/geo/oce/envcomp/north-carolina-2023/LDEO-NC-EA-7-Oct2022.pdf.
Authorization
NMFS has issued an IHA to L-DEO for the potential harassment of small numbers of 30 marine mammal species incidental to a marine geophysical survey off North Carolina in the Northwest Atlantic Ocean that includes the previously explained mitigation, monitoring and reporting requirements.
Dated: May 5, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries Service.
[FR Doc. 2023-10024 Filed 5-10-23; 8:45 am]
BILLING CODE 3510-22-P