|Document Type:||Journal Article|
|Title:||Seasonal changes in downstream migration of age-group 0 chinook salmon in the upper Columbia River|
|Author:||Donn L. Park|
|Journal:||Transactions of the American Fisheries Society|
Recent changes in the environment of the Columbia River caused by dam construction may have affected the timing of migration and the ultimate survival of important races of Chinook salmon (Oncorhynchus tshawytscha) that originated in the upper Columbia River. Three dams built in 1960–1963 on the Columbia River are above its confluence with the Snake River: Priest Rapids Dam (1960), Rocky Reach Dam (1961), and Wanapum Dam (1963). A fourth, Wells Dam, currently under construction, had no effect on juvenile salmon until the summer of 1967. These four reservoirs extend a combined distance of 191 km. Timing of downstream migrations of juvenile Chinook salmon in the upper Columbia River before the completion of these dams was reported by Mains and Smith (1964). Unpublished data on timing in the lower Columbia for catch records of bypass traps at Bonneville Dam are available from the Fisheries Engineering Research Laboratory, U.S. Army Corps of Engineers, North Bonneville, Washington (1946–1953). Studies, begun at Priest Rapids Dam in March 1965 and continued in 1966 to determine the timing of downstream migrations of juvenile Chinook salmon after completion of Priest Rapids, Wanapum, and Rocky Reach Dams, have shown that the change in the environment of the upper Columbia River apparently has affected the downstream movement of juvenile salmon.