FISHERY BULLETIN: VOL. 71, NO. 2 



could be determined without having to extract 

 the magnetic tag from the snout. Fish with 

 recognizable brands were then dart-tagged 

 and released so that further information might 

 be obtained upon recapture upstream or to 

 identify the fish in case it fell back over the 

 dam and ascended the ladder a second time. 

 If a fish was known to be tagged but the 

 brand was indistinguishable, it was tagged 

 with a serially numbered dart and hauled to 

 the Rapid River Hatchery where the fish was 

 allowed to mature for spawn taking. The tag 

 was then extracted after spawning, and the 

 test or control group was determined from 

 the color code. 



The Columbia River gill net fishery below 

 Bonneville Dam, the Indian fishery above the 

 dam, and the sport fishery (primarily below 

 the dam) were sampled throughout the spring 

 Chinook salmon run to provide information 

 concerning the returns of our marked fish to 

 the lower river. Closure of the summer fishery 

 on Chinook salmon prevented sampling of this 

 segment of the run in the lower river. Steel- 

 head trout were sampled in the sport and 

 commercial fisheries of the lower river, but 

 first year returns of fish from those marked 

 in 1969 were insignificant. 



Surveys of spawning grounds were con- 



ducted with 

 Department 

 of Oregon, 

 Department. 

 Snake River 

 and spring 

 grounds in 

 also checked 



the cooperation of the Washington 

 of Fisheries, Fish Commission 



and the Idaho Fish and Game 

 Most of the surveys were in the 

 drainage of Idaho, but hatcheries 

 and summer chinook spawning 



the upper Columbia River were 



for strays. 



RESULTS 



Effect of Transport Mortality 

 and Tag Loss on Analysis 



Two factors that have bearing on the assess- 

 ment of effects of transportation are transport 

 mortality and tag loss. 



Transport mortality is actually a combina- 

 tion mortality resulting from stresses of han- 

 dling, marking, and hauling. During this study, 

 mortality prior to hauling was less than 2% 

 of the total number of fish collected. Of those 

 marked and transported, however, about 5% 

 died. This mortality was subtracted from the 

 tallies of release group data in this report. 

 Attempts were made to determine a delayed 

 mortality after transport. These tests failed 

 because holding conditions were unfavorable 



Groting to cover orifice 



Detector tieod 



FIGURE 2. — Diagrammatic sketch 

 of tag detector and separator device 

 used for adult salmon and trout in 

 south ladder of Ice Harbor Dam. 

 Note trip board deflects tagged fish 

 into trap. 



552 



