UNIT 12 

 PACIFIC COAST SALMON 





Left page: spring spawning 

 chinool< salmon, Columbia 

 River tributary. Right page: 

 Salmon River, near Stanley, 

 Idaho. 



Ecosystem Considerations 



Coho salmon abundance reached a peak in 

 1 ^)76, and has decUned ever since. Chinook salmon 

 abundance has also generally declined since the 

 mid 1970's, although there was a brief increase in 

 chinook salmon abundance in the late 1 980"s. This 

 decline has affected both hatchery and natural 

 stocks and thus appears to indicate a decline in 

 ocean survival. This decline is coincident with a 

 change in the oceanographic regime off the west 

 coast that occurred around 1978. Since then, the 

 coastal waters oftCalilornia, Oregon, and Wash- 

 inqton, where many chinook and coho sahnon 

 stocks mature, have been warmer and less produc- 

 tive than they were in the period from roughly 

 1950 to 1978. The decline in ocean productivity 

 off the Pacific Coast appears to be linked to in- 

 creased productivity in the Gulf of Alaska. Sock- 

 eye, pink, and chum salmon, which migrate fur- 

 ther offshore than chinook and coho salmon, have 

 been relatively stable or increasing during the same 

 period that chinook and coho salmon have de- 

 clined. 



Because Pacific salmon depend on freshwater 

 habitat for spawning and juvenile rearing, they are 

 particularly vulnerable to habitat degradation. 



Throughout their range, their freshwater habitat 

 has been degraded by dam construction, logging, 

 agriculture, grazing, urbanization, and pollution. 

 Water extraction and flow manipulation for hy- 

 dropower, irrigation, flood control, and munici- 

 pal needs directlv compete with salmon for the 

 freshwater on which they depend. As the human 

 population in the western United States contin- 

 ues to increase, so will the pressures on salmon 

 habitat. The fact that we still have salmon in 

 harvestable quantities is a tribute to the resilience 

 of these fish. 



FOR FURTHER READING 



Pacifii; Fishery M.inagement Council. 1998. Review of 

 1997 ocean salmon fisheries. Pacific Fishery Manage- 

 ment Council, 2130 SW Fifth Ave., Portland, OR 

 97201, 107 p. 



Oregon Department of Fish and Wildlife (0L:)F\V) and 

 Washington Department of Fish and Wildlife 

 (WDFW). 1998. Status report: Columbia River fish 

 runs and fisheries 1938-97. ODFW, PC. Box 59, 

 Portland, OR 97207, 299 p. 



Hare, .S. R.. N. J. Mantua, and R. C. Francis. 1999. 

 Inverse production regimes: Alaska and West Coast 

 Pacific salmon. Fisheries 24(1):6-14. 



1 55 



