The National Marine Fisheries Service has issued a letter of authorization allowing WesternGeco, LLC to take marine mammals incidental to a geophysical survey in the Gulf of America. The authorization, issued under the Marine Mammal Protection Act, runs from August 11, 2026 through August 30, 2027.
Survey covers four lease areas
WesternGeco plans a long offset sparse bottom node survey across 1,023 lease blocks in the Keathley Canyon, Alaminos Canyon, Garden Banks, and East Banks areas, in water depths of roughly 900 to 3,000 meters. A bottom node survey places seismic sensors on the seafloor rather than towing them behind a vessel, recording sound signals used to map the rock layers below.
The company will use two source vessels. Each will run either a conventional airgun array of 28 elements with a total volume of 5,000 cubic inches, or a low-frequency tuned pulse source paired with a conventional 28-element, 5,000-cubic-inch airgun array. An airgun array releases bursts of compressed air underwater to generate the sound waves used in the survey.
Regulatory history
NMFS authorizes incidental marine mammal takes from Gulf of America geophysical surveys under regulations at 50 CFR 217.180 et seq. The agency issued the original five-year rule in January 2021, then found it relied on erroneous take estimates and issued a corrected rule effective May 24, 2024. NMFS's Office of Policy requested reimplementation of the take regulations on August 28, 2025 to avoid a lapse in coverage, and the Bureau of Ocean Energy Management joined as a co-petitioner on October 20, 2025. The resulting rule took effect April 20, 2026 and runs through April 19, 2031, carrying forward the same mitigation, monitoring, and reporting requirements as before.
