Decline and Recovery of Snake River Salmon

James J. Anderson
University of Washington

Introduction
Columbia River stock declines resulted from long term loss of habitat, commercial harvest, changes in the ocean, and development of the hydrosystem.

The completion of Snake River dams in 1976 changed the river ecology. To mitigate these changes fish are now barged from Snake River dams to below Bonneville dam. Coincident with hydrosystem completion and barging, the ocean went through a fundamental change which decreased survival of fish entering the ocean.

Declines in the Columbia and Snake River salmon populations began well before the construction of the hydroelectric projects. Significant events for Columbia River chinook populations include:

• Fishery expansion between 1865 and 1885
• Stable fishery between 1885 and 1920
• Fishery decline after 1920
• Population declined to record lows after 1977
• First dam on-line in 1932, last dam on-line in 1982
• Snake River populations declared Endangered in 1992