EGG-TO-MIGRANT SURVIVAL OF SPRING CHINOOK SALMON 

 (ONCORHYNCHUS TSHAWYTSCHA) IN THE YAKIMA RIVER, WASHINGTON 



By Richard L. Major and James L. Mighell, Fishery Biologists 



Bureau of Commercial Fisheries Biological Laboratory 



Seattle, Washington 98102 



ABSTRACT 



Egg-to-migrant survival for the 1957-61 broods 

 ranged from 5.4 to 16.4 percent — the first estimates of 

 survival of chinook salmon in a large river system. 



Spring Chinook salmon spavfn in the American, 

 Bumping, and Naches Rivers and Rattlesnake Creek — 

 tributaries of the Yakima River — and in the upper 

 stretch of Yakima River proper. For both sexes, spawning 

 fish in the upper Yakima River are smaller than those 



in the other areas. Mean lengths (mideye to end of 

 hypural plate) were 45.5 and 57..? cm. for the males and 

 feinales in the upper Yakima River and 65.4 and 71 

 cm. for the males and females in the other areas. 



Spring Chinook salmon migrate to sea in their second 

 year. Larger fish migrate earlier in the season than do 

 smaller fish. Seaward migration reaches a peak at 

 Prosser, Wash., on the lower Yakima River between 

 April 14 and May 19. Movement tends to be nocturnal. 



Knowledge about the life history of a species 

 of fish is fundamental to its effective management. 

 For Pacific salmon (Oncorhynchvs spj).), some con- 

 ception is required of survival from the egg to 

 the seaward migrant stage. Survival from egg to 

 migrant has been measured for four of the five 

 species that s])awn in North America — sockeye, 

 pink, chum, and coho salmon (0. nerka, 0. gor- 

 hiischa, 0. keta, and 0. kisutch) — but comparable 

 information is almost completely lacking for 

 chinook salmon {0. tshawytscha) . For the race 

 of chinook salmon known as spring chinook, sur- 

 vival has never been measured mainly because 

 this race spawns in large river systems where 

 sampling is difficult.' 



The Columbia River, although its runs have 

 been reduced to a fraction of their former size, 

 continues to be a major producer of spring chinook 

 salmon. To estimate the egg- to -migrant survival 

 of a population of spring chinook salmon, the 

 Bureau of Commercial Fisheries began a study 

 in 1957 on the Yakima River, a tributary of the 

 Columbia River in south-central Washington (fig. 



' Seasonal races of chinoot salmon in the Columbia River system are 

 classified as spring, summer, or fall chinook depending on the time of year 

 that the adults enter the river to spawn. In tributaries that contain more 

 than one seasonal race, the spawning of spring chinook salmon is separated 

 in time and space from the spawning of the other races. 



Published January 1969. 



FISHERY BULLETIN: VOL. 67, NO. 2 



1). The Yakima River was chosen because a trap 

 in a diversion canal at Prosser, Wash., on the 

 lower river provided a unique opportunity to 

 sample the seaward migration. The trap allowed 

 us to estimate the number of seaward migrants 

 each year. Comparison of the number of migrants 

 with the number of eggs deposited by the female 

 spawners in the appropriate brood year yielded 

 an estimate of survival to the seaward migrant 

 stage. This paper is a summary of our work on 

 the Yakima River from 1957 to 1963. 



SPAWNING OF SPRING CHINOOK 

 SALMON 



The aim of our studies of adult spring chinook 

 salmon was to estimate the number of eggs de- 

 posited. We had to determine (1) the distribution 

 and abundance of redds, (2) the size, age, and 

 fecundity of the spawners, and (3) the number of 

 eggs retained by female spawners. 



DISTRIBUTION AND ABUNDANCE OF REDDS 



The spawning grounds of spring chinook salmon 

 in the Columbia River system were originally de- 

 lineated in the 1930's (Bryant and Parkhurst, 

 1950) . For the Yakima River system, the following 



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