SPECIES DISTRIBUTION 



The distribution of Snake River fall chinook salmon has been dramatically reduced to a portion 

 of its former range. The construction of Brovvnlee (1958). Oxbow (1961). and Hells Canyon 

 (1967) Dams inundated spawnmg habitat and prevented access to the primarv' production areas of 

 Snake River fall chinook salmon. 



Critical Habitat 



Critical habitat for SnakeTliver fall chinook salmon consists of river reaches of the Columbia, 

 Snake, and Salmon Rivers, and all tributaries of the Snake and Salmon Rivers presently or 

 historically accessible to Snake River fall chinook salmon (except reaches above impassable 

 natural falls, and Dworshak and Hells Canyon Dams). 



MAJOR IMPACTS 



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

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

 Columbia Rivers; predation on juvenile salmon in reservoirs: and increased delay of adults on 

 their way 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 salmon habitat. 



Current ocean and river harvest levels have been reduced in the commercial, recreational, and 

 tribal fisheries due to low escapements and efforts to protect these runs. 



The impacts of potential bacterial, protozoan, viral, and parasitic organisms on Snake River fall 

 chinook salmon are largely unknown. Predators include the northern squawfish and marine 

 mammals such as harbor seals and California sea lions. The extent to which predation is a factor 

 causing the decline of fall chinook salmon is unknown. 



Drought and poor ocean survival are the principal natural factors that may have contributed to 

 reduced fall chinook salmon production. The recent straying of fall chinook salmon from other 

 areas into the Snake River threatens the genetic integrity of wild Snake River fall chinook 

 salmon. 



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