Background

The Mokelumne River supports Central Valley fall-run Chinook salmon (Oncorhynchus tshawytscha) (fall-run), which is the only salmon run known to naturally occur in this waterway (Clark 1929). Fall-run are listed as a Species of Concern under the federal Endangered Species Act (NMFS 2004).The Mokelumne River Hatchery (MOK) conducts artificial propagation of fall-run to enhance economically important commercial fisheries and popular sport fisheries in the ocean and rivers of California.

Camanche Dam, which impounds Camanche Reservoir is the upper limit of anadromous fish migration in the Mokelumne River. East Bay Municipal Utility District (EBMUD) initiated construction of Camanche Reservoir in 1963. As mitigation for blocking access to spawning grounds for salmonids, EBMUD provided funding for the original construction of the MOK in 1964.The MOK is located on the south bank of the Mokelumne River at the base of Camanche Dam. While EBMUD provides funding for fall-run production, the California Department of Fish and Wildlife (CDFW) administers and operates the hatchery. The Commercial Salmon Stamp Fund provided funding for an additional MOK building built in 2002 and continues to financially support the MOK. On an annual basis the MOK produces fall-run for mitigation (Mitigation Element) and for ocean salmon enhancement (Ocean Enhancement Element). The annual MOK production goal is 6,400,000 fall-run smolts (3,400,000 for Mitigation Element and 3,000,000 for Ocean Enhancement Element). The MOK receives requests from researchers to produce small numbers of fall-run smolts for special studies (Special Studies Element). Special Studies Element production is separate from Mitigation and Ocean Enhancement elements and varies in quantity annually or may not occur.

References
Clark, G. H. 1929. Sacramento-San Joaquin Salmon (Oncorhynchus tschawytscha) Fishery of California. Division of Fish and Game of California, Bureau of Commercial Fisheries, Fish Bulletin No. 17. 73 pp., 32 figs.

NMFS (National Marine Fisheries Service). 2004. Endangered and Threatened Species; Establishment of Species of Concern List, Addition of Species to Species of Concern List, Description of Factors for Identifying Species of Concern, and Revision of Candidate Species List Under the Endangered Species Act. Federal Register / Vol. 69, No. 73 / Thursday, April 15, 2004