Central Coast coho salmon (Oncorhynchus kisutch)

Central Coast coho salmon (Oncorhynchus kisutch)
Name	Central Coast coho salmon
Genus	Oncorhynchus
Species	kisutch
Status	Threatened (ESA)

Contents

Central Coast coho salmon (Oncorhynchus kisutch) is an evolutionarily significant population segment of coho salmon native to the central coast of California and southern Oregon. This population has been the focus of recovery planning under the Endangered Species Act of 1973 and has been studied by agencies such as the National Oceanic and Atmospheric Administration and the California Department of Fish and Wildlife. Research and monitoring involve academic institutions including the University of California, Davis, the Oregon State University, and conservation NGOs such as the Pacific Coast Federation of Fishermen's Associations.

Taxonomy and description

Central Coast coho belong to the genus Oncorhynchus and species Oncorhynchus kisutch, a member of the family Salmonidae and order Salmoniformes. Morphologically, adult coho typically display silver flanks and small black spots like other Pacific salmon described in taxonomic works by David Starr Jordan and field guides used by the American Fisheries Society. During spawning, males develop pronounced kypes and change coloration, traits documented in monographs by the U.S. Fish and Wildlife Service and researchers at the Smithsonian Institution. Diagnostic keys used by the California Academy of Sciences contrast coho with sympatric species such as Oncorhynchus mykiss and Oncorhynchus tshawytscha.

The Central Coast coho ESU historically occupied coastal streams from the Russian River region to the Santa Cruz Mountains and into southern Oregon watersheds such as the Rogue River basin. Contemporary distributions are fragmented, with extant populations recorded in watersheds managed by county agencies like Monterey County and Santa Cruz County and federal lands including the Los Padres National Forest and Siskiyou National Forest. Habitat types include small headwater tributaries, estuarine complexes at mouths near the Monterey Bay National Marine Sanctuary, and riparian corridors adjacent to protected areas like the Redwood National and State Parks. Surveys conducted by the National Marine Fisheries Service and the California Coastal Conservancy map occurrences in tributaries of the San Lorenzo River, Nicasio Creek, and other named streams.

Central Coast coho exhibit an anadromous life cycle characteristic of Pacific salmon described in textbooks used at the University of Washington and the University of British Columbia. Juveniles rear for one year in freshwater streams influenced by instream structures cataloged by the U.S. Forest Service and then migrate to the pelagic environment of the Pacific Ocean where they interact with ecosystems studied by the Monterey Bay Aquarium Research Institute. Diet shifts documented by researchers at the Scripps Institution of Oceanography include consumption of aquatic insects in natal streams and forage fish in marine phases examined by the National Oceanic and Atmospheric Administration Fisheries program. Predators and competitors include species monitored by the California Department of Fish and Wildlife and the Oregon Department of Fish and Wildlife, and ecological dynamics are influenced by climatic drivers analyzed by the National Aeronautics and Space Administration and the National Weather Service.

Population assessments by the National Marine Fisheries Service and status reviews in reports to the U.S. Congress indicate that Central Coast coho populations have declined since baseline surveys by the California Department of Fish and Wildlife in the 20th century. Trend analyses published in journals affiliated with the Ecological Society of America and researchers at the Humboldt State University show local extirpations in some watersheds and low abundance refugia in others identified by monitoring programs funded by the Pew Charitable Trusts and the Packard Foundation. The listing as threatened under the Endangered Species Act of 1973 followed petitions and litigation involving environmental organizations such as the Environmental Defense Fund and the Natural Resources Defense Council.

Primary threats include habitat degradation from land-use practices enacted by counties like Santa Clara County and industries regulated under laws such as the Clean Water Act overseen by the Environmental Protection Agency. Key limiting factors are altered stream hydrology from water diversions permitted by state agencies including the California State Water Resources Control Board, sedimentation from timber activities in areas administered by the Bureau of Land Management, and barrier construction by municipal governments. Additional stressors include interactions with aquaculture operations noted by the National Oceanic and Atmospheric Administration, competition and predation involving species monitored by the California Department of Fish and Wildlife, and climate-related shifts reported by the Intergovernmental Panel on Climate Change and researchers at the National Center for Atmospheric Research.

Recovery planning efforts are coordinated by the National Marine Fisheries Service in collaboration with state agencies such as the California Department of Fish and Wildlife and conservation groups including the The Nature Conservancy and the Sierra Club. Actions include habitat restoration projects funded by the California Coastal Conservancy and grant programs administered by the U.S. Fish and Wildlife Service and regional collaboratives like the California Salmon Council. Restoration techniques developed in partnership with universities such as the University of California, Santa Cruz involve large woody debris placement and riparian planting implemented on lands owned by entities including the Monterey Peninsula Regional Park District and the Marin Municipal Water District.

Commercial and recreational harvests affecting coho are regulated by the Pacific Fishery Management Council and state commissions including the California Fish and Game Commission and the Oregon Fish and Wildlife Commission. Management measures have included fishery closures, hatchery supplementation overseen by the Warm Springs Hatchery and the Mendocino Fish Hatchery, and harvest quotas negotiated in meetings involving stakeholders such as the Pacific Coast Federation of Fishermen's Associations and tribal governments including the Yurok Tribe and the Confederated Tribes of Siletz Indians. Enforcement and compliance efforts involve agencies like the National Marine Fisheries Service and local enforcement by county sheriffs in coastal counties.

Category:Oncorhynchus Category:Fish of California Category:Fish conservation