i ii Most NOAA Technical Memorandums NMFS-NWFSC are available on-line at the Northwest Fisheries Science Center web site (http://www.nwfsc.noaa.gov) Copies are also available from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone orders (1-800-553-6847) e-mail orders (
[email protected]) iii iv v vi vii viii ix x xi xii xiii EXECUTIVE SUMMARY In 1994, the Northwest Region of the National Marine Fisheries Service (NMFS) received three petitions to list distinct populations of chum salmon (Oncorhynchus keta) from Puget Sound and the Strait of Juan de Fuca as threatened or endangered species under the Endangered Species Act (ESA). In response to these petitions and the more general concerns for the status of Pacific salmon throughout the region, NMFS announced that it would initiate ESA status reviews for all species of anadromous salmonids in the Pacific Northwest. These comprehensive reviews will consider all populations in the states of Washington, Idaho, Oregon, and California. This report summarizes the conclusions of the NMFS Biological Review Team (BRT) for the ESA status review of chum salmon. According to NMFS policy, populations of Pacific salmon will be considered “distinct” (and hence “species” as defined by the ESA) if they represent evolutionarily significant units (ESUs) of the biological species. Based on ecological, genetic, and life-history information developed during this status review from across the species range, the BRT identified four ESUs of chum salmon in the Pacific