Bibliography Background About KRIS

Status of Pacific Salmon Species in Northwestern California

Despite the paucity of fish counts to clearly establish adult trend data for steelhead and coho salmon, there is sufficient evidence to indicate that these species have dropped to low or critically low levels in Mendocino County. The range of coastal cutthroat trout does not extend south of the Eel River and there is no historic confirmation of their occurrence on the Mendocino coast. The risk of extinction for Pacific salmon species in northwestern California has been recognized clearly for nearly a decade (Nehlsen et al., 1991; Higgins et al., 1992).

Chinook Salmon

Chinook may have occurred in coastal streams of Mendocino County (Myers et al., 1999) but there are no early records of catches from rivers in the area. Since chinook salmon return to the Mattole River to the north, which had a less intensive history of early-day land use, and to the Russian River in the south, it is likely that chinook salmon did once inhabit coastal rivers in Mendocino County. There are still chinook in Mendocino County in tributaries of the Eel River and Russian River. Chinook are mainstem spawners and would have been eliminated from Mendocino coastal rivers by splash damming during periods of early logging. Chinook juveniles also rear in coastal estuarine environments to increase in size which improves ocean survival. Historic photos show that sediment from early watershed disturbance completely filled the estuary of the Noyo River by early in the 20th century. Chinook salmon have recently been proposed as a threatened species in northern California coastal streams south of the Klamath River (NOAA, 1998).

Coho Salmon

The National Marine Fisheries Service listed coho salmon as threatened under the Endangered Species from Mendocino to Santa Cruz counties in October 1996 (61 FR 56138) and those from the Mattole north to the Oregon coast in May 1997 (62 FR 24588). Specific data on adult returns is available for only a few locations but Brown et al. (1994) estimated statewide returns of wild adult coho at 5,000 to 13,000 fish as of 1987-1990, as compared to rough estimates of 200,000 to 500,000 in the 1940s. The complete absence of coho from a large number of streams throughout their range in California indicates that the distribution of the species has become fragmented. Adams et al. (1999) provided presence-absence data for all areas from Mendocino to Santa Cruz (Central Coast ESU), including tributaries of San Francisco Bay and found coho absent from 49% of the area's former coho streams. See Fish Population Information in KRIS.

Brown et al. (1994) summarized data from Mendocino County coastal rivers and streams and found that they showed the same pattern as that reported  by Adams et al (1999) with small coastal streams having a 50% absence rate but some larger tributaries, such as the Noyo River still retaining coho in more than 80% of the tributaries which historically had them. 

Brown et al. (1994) "found coho salmon populations to be low in all 82 streams (571 kilometers) surveyed in Mendocino County. Only the Noyo River, which is routinely planted with large numbers of fry and smolts, had a population of greater than 500 individuals." Coho salmon typically spawn as three-year-olds, which means that fish of the same year class usually return to spawn together. Loss of a year class due to storm events or severe drought can cause a lack of spawners in a cycle of no adult returns every three years. Strong and weak year classes occur in many Mendocino coastal streams and are another sign of extinction risk.

Most recent California coho status reviews (NMFS, 2001; CDFG, 2002) indicate that the species continues to decline and their status to worsen. Of the Central California ESU, NMFS (2001) stated that: “The Central California Coast ESU is presently in danger of extinction. The condition of coho salmon populations in this ESU is worse than indicated by previous reviews.” The recently released California Department of Fish and Game (CDFG, 2002) Status Review of Coho Salmon North of San Francisco characterized the coho population in the same region a as follows. “Extant populations in this region appear to be small. Small population size along with large-scale fragmentation and collapse of range observed in data for this area indicate that metapopulation structure may be severely compromised and remaining populations may face greatly increased threats of extinction because of it. For this reason, the Department concludes that coho salmon in the Central Coast Coho ESU are in serious danger of extinction throughout all or a significant portion of their range.” 

Steelhead Status

Busby et al. 1996 characterized steelhead status as follows: "Northern California--This ESU occupies river basins from Redwood Creek in Humboldt County, California south to the Gualala River, inclusive, and includes winter and summer steelhead. Allozyme and mitochondrial DNA data indicate genetic discontinuities between steelhead of this region and those to the north and south. Freshwater fish species assemblages in this region are derived from the Sacramento River Basin, whereas streams to the north include fishes representative of the Klamath-Rogue ichthyofaunal province. Population abundances are very low relative to historical estimates, and recent trends are downward in stocks for which we have data, except for two small summer steelhead stocks. Summer steelhead abundance is very low. Risk factors identified for this ESU include freshwater habitat deterioration due to sedimentation and flooding related to land management practices and introduced Sacramento squawfish as a predator in the Eel River. For certain rivers (particularly the Mad River), the Biological Review Team (BRT) is concerned about the influence of hatchery stocks, both in terms of genetic introgression and potential ecological interactions between introduced stocks and native stocks."


Busby, P.J., T.C.Wainwright, and G.J.Bryant. 1996. Status Review of West Coast Steelhead from Washington, Oregon and California. NOAA Technical Memorandum NMFS-NWFSC-27. National Marine Fisheries Service. Seattle WA.

Brown, L.R., P.B. Moyle, and R.M. Yoshiyama. 1994. Historical Decline and Current Status of Coho Salmon in California. North American Journal of Fisheries Management. 14(2):237-261. 

California Department of Fish and Game. 1965.  (Excerpts from) California Fish and Wildlife Plan.  Volume III.  Supporting Data.  Part B. Inventory (Salmon-Steelhead and Marine Resources).  Pages 323-338+.  Sacramento, CA.  1051 pp.

CA Department of Fish and Game. 2002. Status Review of California Coho Salmon North of San Francisco. Report to the California Fish and Game Commission. California Department of Fish and Game, Sacramento, CA. 336pp.

Hassler, T.J. and C.M. Sullivan, and G.R. Stern. 1991. Distribution of coho salmon in California. Final report submitted to California Department of Fish and Game, contract no. FG7292. US Fish and Wildlife Service, California Cooperative Fishery Research Unit. Humboldt State University. Arcata, CA. 23 pp. [103k]

Higgins, P.T., S. Dobush, and D. Fuller. 1992. Factors in Northern California Threatening Stocks with Extinction. Humboldt Chapter of American Fisheries Society. Arcata, CA. 25pp.

Myers, J.M., R.G. Kope, G.J. Bryant, et al. 1998. Status Review of Chinook Salmon from Washington, Idaho, Oregon, and California. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-35, 443 p.

National Marine Fisheries Service (NMFS). 1996. Factors for Decline: A supplement to the Notice of Determination for West Coast Steelhead under the Endangered Species Act. NMFS Protected Species Branch (Portland, OR) and NMFS Protected Species Management Division (Long Beach, CA). 82 pp.

National Oceanic and Atmospheric Administration (NOAA). 1998. Endangered and Threatened Species: Proposed Endangered Status for Two Chinook Salmon ESUs and Proposed Threatened Status for Five Chinook Salmon ESUs; Proposed Redefinition, Threatened Status, and Revision of Critical Habitat for One Chinook Salmon ESU; Proposed Designation of Chinook Salmon Critical Habitat in California, Oregon, Washington, Idaho. National Marine Fisheries Service (NMFS), NOAA, Commerce. Federal Register/Vol. 63, No. 45/Monday, March 9, 1998/Proposed Rules. 40 pp.

National Marine Fisheries Service (NMFS). 2001. Status Review Update for Coho Salmon (Oncorhynchus kisutch) from the Central California Coast and the California portion of the Southern Oregon/Northern California Coasts Evolutionarily Significant Units. NMFS, Southwest Fisheries Science Center. Santa Cruz, CA. 49 pp. without appendices.  or if you want the appendices: 3.6Mb

Nehlsen, W., J.E. Williams, J.A.Lichatowich. 1991. Pacific Salmon at the Crossroads: Stocks at Risk from California, Oregon, Idaho, and Washington. Fisheries 16(2):4-21. 

Prager, M., P. Spencer, T. Williams, S. Kramer, P. Adams, and T. Hablett. 1999. Southwest Regional  approach to data collection on California coastal salmonids. A report of a workshop held August 12-13, 1998. Administrative Report SC-99-03NMFS. NMFS Southwest Regional Office and Southwest Fisheries Science Center. 46 pp. [239 kb]

Rieman, B. 1993. Consideration of Extinction Risks for Salmonids. As FHR Currents # 14. US Forest Service, Region 5. Eureka, CA. 12 pp.