The comraercial take of blueback salmon in I9J47 exceeded all -atcn- 

 since 1925 and the escapement (coxmt of fish over Bonneville Daai minus 

 the catch above Bonneville) was the largest since counting was started 

 at Bonneville in 1938, This large escapement caused West Coa^t fishery- 

 agencies to become concerned about the capacity of the limited remaining 

 stream areas to accoiriinodat.e the larger number of spaxmerso A surrey was 

 therefore maae to determine the density of populations and the probabie 

 success of natural spawning of blueback salmon utilizing the remaining 

 rearing grounds in the Wenatchee and Okanogan River systew:;. 



The earlier parts of this work were done at the direcoiOii . ' Joseph 

 To Barnaby, formerly Chief ^ North Pacific Fishery Investigations,, Ral}.h 

 P. Silliman was in charge of the first field surveys <> Grateful ackncwl<^'-'r-'e' 

 ment is due Floyd G„ Bryant, A. A. Gentry, Zeil E» Parkhurst and K. G, 

 Weber for their active participation and helpful suggestions in the prepa- 

 ration of this report. 



A BRIEF HISTORY OF COLUMBIA RIVER BLUEBACKS 



The blueback salmon (0. nerka) , unlike ether salmon, generally deposits 

 its eggs in streams tributary to lakes or on the shores of lakes theicselvo^o 

 On emerging from the gravel, the 2'oung usually spend one or more years in 

 the lake before making the seaward migration. Most lakes suitable for 

 propagation of bluebacks have been lost through the development of power 

 and irrigation projects o High dams without fish facilities, and irrigavioi; 

 canals without proper screening for downstream migrants, have combined to 

 deplete the rearing areas (Rich 19U2j po 106), 



The known blueback spawning areas (figure 1) of the Colum.bia Pivei" 

 system., have never been as numerous as those for the Chinook salmon » They 

 include the Payette and Redfish Lakes in Idaho, Wallowa Lake in Oregon,, the 

 lakes of the Yakima River system in Washington, and the Arrow and Upper 

 Okanogan Lakes in Canada,, all of which have been isolated by darasol/ 



The last of these systems to be eliminatedj the Arrow Lakes ^ was 

 isolated by Grand Coulee Dam« To compensate for the loss of spawning area 

 the Uo S, Bureau of Reclamation built three hatcheries and financed reloca- 

 tion of bluebacks and other species of fish« All bluebacks were placed in 

 t\-io remaining spawning and rearing areas , (1) the Lake Wenatchee regior,. in 

 central Washington, and (2) Lake Osoyoos which lies in Canada and north 

 central Washingt-cr, (Jlsh and Hanavan 19i48„ po5)o 



^/ The Redfish Lakes are new accessiblej but the runs had already bean 

 depleted by Sonbeam Dam and have never been restocked. Surveys in the area 

 during the 19U6 and 1.9li7 seasons revealed only six bluebacks „ 



