SPECIES DISTRIBUTION 



Snake River spring/summer chinook spawn in the many streams associated with the large. 

 complex Clearwater, Grande Ronde, and Salmon Rivers and in the mainstem of the Tucannon 

 and Imnaha Rivers, as well as in Asotin. Granite, and Sheep Creeks (between Lower Granite and 

 Hells Canyon Dams). 



Critical Habitat 



Critical habitat for Snake River spring/summer chinook salmon includes river reaches of the 

 Columbia. Snake, and Salmon Rivers, and all tributaries of the Snake and Salmon rivers (except 

 the Clearwater River) presently or historically accessible to Snake River spring/summer chinook 

 salmon (except reaches above natural falls and Hells Canyon Dam). 



MAJOR IMPACTS 



Overfishing has contributed significantly to the population decline of chinook salmon. 



Hydropower development has resulted in the following: blockage and inundation of habitat: 

 turbine-related mortality of juvenile fish; increased delay of juvenile migration through the Snake 

 and Columbia rivers; increased predation on juvenile salmon in reservoirs; and increased delay 

 of adults migrating to spawning grounds. Water withdrawal and storage, irrigation diversions, 

 siltation and pollution from sewage, farming, grazing, logging, and mining have also degraded 

 the Snake River spring/summer chinook salmon habitat. 



Snake River spring/summer chinook are rarely taken in ocean fisheries. Small numbers of 

 spring/summer chinook are incidentally harvested in Columbia River Indian and non-Indian 

 fisheries directed at other species. Fisheries for Snake River spring/summer chinook have been 

 closed for more than 20 years. 



Hatchery programs may have contributed to the further decline of wild Snake River 

 spring/summer chinook salmon through the taking of fish for broodstock purposes, behavioral 

 and genetic interactions between wild and hatchery reared salmon, competition, predation and 

 the spread of disease. 



54 



