Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 6856
Title: Snake River spring and summer chinook salmon: can they be saved?
Author: John G. Williams
Publication Year: 1988
Journal: Regulated Rivers: Research and Management
Volume: 4
Issue: 1
Pages: 17-26

Spring and summer chinook salmon Oncorhynchus tshawytscha populations from the Snake River have declined precipitously from historical levels.  Declines initially were the result of overfishing, but since the late 1950s they have been primarily the result of hydroelectric dams that blocked access to spawning areas, created slack water, and caused mortalities of juvenile migrants.  Mitigation hatcheries and juvenile collection and bypass systems at dams, transportation of juveniles from upriver dams to a release site on the lower Columbia River, a water budget, allocated spill for fish at main–stem dams have not increased these populations appreciably.  Ocean conditions may have been a factor in the low returns from 1976 through 1984, but the factors currently considered as controlling the viability of the run are the low genetic variability, lack of stress tolerance, and incidence of bacterial kidney disease inherent in the stock.  With control of disease, reduced stress at main–stem projects, and continued efforts to maintain genetic variability, the chinook salmon populations should increase and their long–term viability should be assured.