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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 the Lamont-Doherty Earth Observatory of Columbia University (L-DEO) to incidentally harass marine mammals during survey activities associated with a marine geophysical survey at the Chain Transform Fault in the equatorial Atlantic Ocean.
DATES:
The authorization is effective from September 27, 2024 through September 26, 2025.
ADDRESSES:
Electronic copies of the application and supporting documents, as well as a list of the references cited in this document, may be obtained online at: https://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 below.
FOR FURTHER INFORMATION CONTACT:
Jenna Harlacher, Office of Protected Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the “take” of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are proposed or, if the taking is limited to harassment, a notice of a proposed IHA is provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other “means of effecting the least practicable adverse impact” on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (referred to in shorthand as “mitigation”); and requirements pertaining to the monitoring and reporting of the takings. The definitions of all applicable MMPA statutory terms cited above are included in the relevant sections below.
Summary of Request
On April 15, 2024, NMFS received a request from L-DEO for an IHA to take marine mammals incidental to conducting a marine geophysical survey of the Chain Transform Fault in the equatorial Atlantic Ocean. Following NMFS review of the application and additional clarifying information from L-DEO, NMFS deemed the application adequate and complete on May 22, 2024. L-DEO's request is for take of 28 marine mammal species by Level B harassment, and for take of a subset of 5 of these species, by Level A harassment. Neither L-DEO nor NMFS expect serious injury or mortality to result from this activity and, therefore, an IHA is appropriate. There are no changes from the proposed IHA to the final IHA.
Description of Activity
Researchers from the Woods Hole Oceanographic Institution, University of Delaware, University of New Hampshire, Boise State University and Boston College, with funding from the National Science Foundation, plan to conduct a high-energy seismic survey using airguns as the acoustic source from the research vessel (R/V) Marcus G. Langseth (Langseth), which is owned and operated by L-DEO. The survey would occur at the Chain Transform Fault, off the coast of Africa, in the equatorial Atlantic Ocean during austral summer 2024 in the Southern Hemisphere ( i.e., between October 2024 and February 2025). The survey would occur within International Waters more than 600 kilometers (km) in the Gulf of Guinea, Africa, in water depths ranging from approximately 2,000 to 5,500 meters (m). To complete this survey, the R/V Langseth would tow a 36-airgun array with a total discharge volume of approximately (~) 6,600 cubic inches (in3 ) at a depth of 9 to 12 m. The airgun array receiving system would consist of a 15 km long solid-state hydrophone streamer and 20 Ocean Bottom Seismometers (OBS). The airguns would fire at a shot interval of 37.5 m (~18 seconds (s)) during seismic acquisition. Approximately 2,058 km of total survey trackline are planned. Airgun arrays would introduce underwater sounds that may result in take, by Level A and Level B harassment, of marine mammals.
A detailed description of the planned geophysical survey was provided in the Federal Register notice of the proposed IHA (89 FR 56158, July 8, 2024). Since that time, no changes have been made to the planned survey activities. Therefore, a detailed description is not provided here. Please refer to that Federal Register notice for the description of the specified activity.
Comments and Responses
A notice of NMFS' proposal to issue an IHA to L-DEO was published in the Federal Register on July 8, 2024 (89 FR 56158). That notice described, in detail, L-DEO's activity, the marine mammal species that may be affected by the activity, and the anticipated effects on marine mammals. In that notice, we requested public input on the request for authorization described therein, our analyses, the proposed authorization, and any other aspect of the notice of proposed IHA, and requested that interested persons submit relevant information, suggestions, and comments. The proposed notice was available for a 30-day public comment period. NMFS received no public comments.
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the application summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history of the potentially affected species. NMFS fully considered all of this information, and we refer the reader to these descriptions, instead of reprinting the information. Additional information regarding population trends and threats may be found in NMFS' Stock Assessment Reports (SARs; https://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 ( https://www.fisheries.noaa.gov/find-species). NMFS refers the reader to the aforementioned source for general information regarding the species listed in table 1.
The populations of marine mammals found in the survey area do not occur within the U.S. exclusive economic zone (EEZ) and therefore, are not assessed in NMFS' SARs. For most species, there are no stocks defined for management purposes in the survey area, and NMFS is evaluating impacts at the species level. As such, information on potential biological removal level (PBR; defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population) and annual levels of serious injury and mortality from anthropogenic sources are not available for these marine mammal populations. Abundance estimates for marine mammals in the survey location are lacking; therefore, the modeled abundances presented here are based on a variety of proxy sources, including the U.S Navy Atlantic Fleet Training and Testing Area Marine Mammal Density (AFTT) model (Roberts et al., 2023) and the International Whaling Commission (IWC) Population (Abundance) Estimates (IWC 2024). The modeled abundance is considered the best scientific information available on the abundance of marine mammal populations in the area.
Table 1 lists all species that occur in the survey area that may be taken as a result of the planned survey and summarizes information related to the population, including regulatory status under the MMPA and Endangered Species Act (ESA).
Table 1—Species Likely Impacted by the Specified Activities
Table 2—Marine Mammal Hearing Groups
[NMFS, 2018]
| 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). |
Table 3—Predicted Radial Distances From the R/V Langseth Seismic Source to Isopleth Corresponding to Level B Harassment Threshold
Table 4—Modeled Radial Distance to Isopleths Corresponding to Level A Harassment Thresholds
| Low frequency cetaceans | Mid frequency cetaceans | High frequency cetaceans | |
|---|---|---|---|
| PTS SEL cum | 426.9 | 0 | 1.3 |
| PTS Peak | 38.9 | 13.6 | 268.3 |
| The largest distance (in bold ) of the dual criteria (cumulative sound exposure level (SEL cum ) or Peak) was used to estimate threshold distances and potential takes by Level A harassment. |
Table 5—Authorized Take