FALL CHINOOK SALMON RETURNS TO HATCHERIES 

 IN THE BONNEVILLE DAM POOL AREA, 1945-60 



by 



Eugene M. Maltzeff and Paul D. Zimmer 



Fishery Biologists (Management) 



Bureau of Commercial Fisheries 



U.S. Fish and Wildlife Service 



Portland, Oregon 



ABSTRACT 



From 1938 through 1960 annual fall chinook salmon migrations over Bonneville 

 Dam declined. During the last 16 years, numbers of young salmon released and re- 

 turns of adults to hatcheries increased slightly. The annual average fall chinook 

 salmon counts at Bonneville Dam between 1945 and 1948 were about 270,700 fish, 

 of which 7.4 percent returned to the hatcheries. In more recent years average 

 annual counts over Bonneville Dam dropped to about 153,000 fish; however, numbers 

 of fish returning to hatcheries Increased to about 22.1 percent of the total. 



During 1945-60 approximately 104,000 fall chinook salmon (with a potential of 

 about 247 million eggs) spawned naturally in streams on which hatcheries are lo- 

 cated. 



Hatchery records for 1945-60 indicate combined annual totals of adult fall 

 Chinook salmon returning either to the hatchery or hatchery stream were nearly 

 489,000 fish. For the same period, releases of fry and fingerlings from the hatch- 

 eries totaled about 572,988,000 fish. 



During 1945-60 combined totals of hatchery and natural spawning fall chinook 

 salmon were more than 529,000 fish, having a potential of approximately 1,317 mil- 

 lion eggs. 



INTRODUCTION 



This report has been prepared to show the 

 contribution of hatcheries located in Bonneville 

 Dam pool area in relation to escapement of 

 fish over Bonneville Dam. 



In 1938, the Columbia River system was 

 subjected to a great change. A major hydro- 

 electric development was placed in operation 



at Bonneville Dam, and another, at Grand 

 Coulee, was nearing completion. Since that 

 time many additional dams have been con- 

 structed not only in the main stem of the 

 Columbia River but also in many important 

 tributary streams. Each structure has to some 

 degree adversely affected the runs of migra- 

 tory fish. Mortalities to fingerlings and adults 

 at each power dam plus loss of spawning and 

 rearing areas in inundated sections of streams 



