92, 94, and 85 percent of the total that had 

 passed Rock Island Dam migrated to the up- 

 per Columbia River." 



When Grand Coulee Dam was built, sockeye 

 salmon that spawned in the upper Columbia 

 River were intercepted at Rock Island Dam 

 and transplanted to the Wenatchee and Oka- 

 nogan Rivers. Before this transplant, numer- 

 ous improvements were made in these streams 

 to pi'otect the fish during migration. Runs 

 that were successfully transplanted are main- 

 tained in these streams. 



The spawning escapement, as reflected by 

 counts at Rock Island Dam, range from a low 

 of less than 1,000 in 1941 to about 170,000 in 

 1966 (fig. 5). The escapement in 1941 was 

 responsible for a small run (11,000 fish) in 

 1945. At the next cycle (1949) the run was 

 well on its way to recovery with 53,000 sockeye 

 salmon, and the 1953 run had an estimated 

 total of 260,000 fish. Runs during the next 

 two cycle years (1957 and 1961) declined, how- 

 ever. 



The trend of the Columbia River sockeye 

 salmon run, as indicated by the least squares 

 method, demonstrates a slight upward slope 

 since 1938. It appears that the highs are 

 nearly equal to the lows and the average run 

 is about 150,000 fish. 



Apparently the decline in abundance of this 

 species (from the records of the fishery in 

 1895-1925), therefore, was the result of the 

 combined effect of the commercial fisheries in 

 the lower river, fishing on the spawning 

 grounds, and complete blocking of most spawn- 

 ing grounds. 



Future of Sockeye Salmon Runs 



Runs of sockeye salmon in the Columbia 

 River could be quickly jeopardized by unfa- 

 vorable conditions at either or both of the two 

 major production areas. Poor survival of 

 spawning stock was recognized as a serious 

 problem by Craddock and Parks (1962), who 

 estimated that only about 10,000 spawners of 

 the escapement of 20,000 was left in 1961 to 

 perpetuate the run. If a proposed water use 



360 



320 



240 



IZ 200 - 



^ It was later discovered that Zosel Dam was not 

 "fish tight" and unknown numbers were able to swim 

 under its gates. We now realize that the percentage 

 of the sockeye salmon from the upper Columbia River 

 was smaller than indicated. 



1938 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 

 YEAR 



Figure 5.— Sockeye salmon runs of the Columbia River 

 and counts at Rock Island Dam, 1938-67. Straight line 

 is derived from the least scjuares method. [Data from 

 Fish Commission of Oregon and Washington Department 

 of Fisheries (1968).] 



development for the Wenatchee River (now be- 

 ing held in abeyance) were developed, the runs 

 would be even more difficult to maintain and 

 might be completely eliminated. 



In the Okanogan River, often a large per- 

 centage of the spawning population is made 

 up of the smaller 3-year-old sockeye salmon 

 rather than of the usual 4-year-old fish. The 

 3-year-olds have a large percentage of males 

 (60 percent or greater). 



The numbers of each age group that pass 

 Rock Island and Zosel Dams on the main Co- 

 lumbia and Okanogan Rivers, respectively, 

 have been compared with those observed on 

 the spawning grounds; a preferentially higher 

 survival of 3-year-old fish was noted. More- 

 over, the smaller sockeye salmon have fewer 

 eggs. Water temperatures above the optimum 

 during July, August, and September in the 

 Okanogan River caused unknown numbers of 



28 



