Tomorrow, NOAA Fisheries is publishing a proposed rule to modify existing regulations and Letters of Authorization (LOAs) under the Marine Mammal Protection Act that govern incidental take of marine mammals by the U.S. Navy in the Hawaii-Southern California Training and Testing (HSTT) Study Area. NOAA Fisheries proposes to authorize two additional takes of large whales by serious injury or mortality by vessel strike over the remainder of the HSTT authorization period (through December 2025). The current HSTT regulations (50 CFR Part 218, Subpart H) and LOAs authorize the take of three large whales by serious injury or mortality by vessel strike. This proposed modification is based upon new information regarding U.S. Navy vessel strikes in southern California. In 2021, two separate U.S. Navy vessels struck unidentified large whales off the coast of southern California on two separate occasions, one whale in June 2021 and one whale in July 2021. In May 2023, a U.S. Navy vessel struck another large whale off the coast of southern California. Based on available photos and video, NMFS and the Navy have determined this whale was either a fin whale or sei whale. Separately, a foreign naval vessel struck two fin whales in southern California in May 2021. Given the new information regarding U.S. Navy vessel strikes of large whales off the coast of southern California, the proposed rule includes a revised analysis of vessel strike in the HSTT Study Area and a proposal to authorize two additional takes by serious injury or mortality for large whales from vessel strikes, beyond that authorized in the 2020 HSTT final rule <https://www.federalregister.gov/documents/2020/07/10/2020-14181/taking-and-importing-marine-mammals-taking-marine-mammals-incidental-to-the-us-navy-training-and> . NOAA Fisheries is seeking comment on this proposed rule for 45 days and will consider all information, suggestions, and comments related to the rule during the development of final regulations governing the incidental taking of marine mammals by the Navy, if final regulations are appropriate. -- *Leah Davis *(she/her) Biologist, Permits and Conservation Division Office of Protected Resources | NOAA Fisheries (301) 427- 8431 www.fisheries.noaa.gov