USFWS proposes to revise the critical habitat designation for the Florida manatee (Trichechus manatus latirostris) and to designate critical habitat for the Antillean manatee (T. m. manatus), under the ESA. In 1976, they designated critical habitat of approximately 965,394 acres (ac) (390,681 hectares (ha)) in Florida for the Florida manatee based on where large concentrations of manatees were known to occur at the time, but no critical habitat was ever designated for the Antillean manatee subspecies. After a review of the best scientific data available, they propose to revise the existing designated critical habitat for the Florida manatee and designate critical habitat for the Antillean manatee based on the physical or biological features essential to the conservation of each subspecies. The total proposed designation for Florida manatee is 1,904,191 ac (770,599 ha) and 78,121 ac (31,614 ha) for the Antillean manatee subspecies. They also announce the availability of an economic analysis of the proposed revised designation of critical habitat for the Florida manatee and proposed designation for the Antillean manatee. They will accept comments received or postmarked on or before 25 November 2024. POC is Nikki Colangelo, Acting Classification and Recovery Division Manager, USFWS, Florida Ecological Services Field Office, 777 37th Street, Suite D-101, Vero Beach, Florida 32960; tele 772-226-8138. (Federal Register 24 September 2024 [Proposed Rule] Pages 78134-78198)