O Control 69 

 • Transport '69 

 D Control 70 

  Transport'70 



Figure 2.— Location of recoveries of tagged adult chinook salmon returning to spawning 



grounds from 1969-70 experiments. 



were from the group released at Bonneville Dam. 

 The transport benefit for the groups of juveniles 

 released at Bonneville becomes 78% when com- 

 puted on the basis of the number of juveniles 

 released per group. 



Too few tagged adult chinook (five Bonneville 

 transports and one control) from the 1970 juvenile 

 releases were collected in 1972 from all sources to 

 make conclusions regarding the effect of trans- 

 portation. 



Discussion 



Results from this study, which was a continua- 

 tion of a study begun by Ebel et al. (1973), 

 corroborated earlier findings, i.e., homing of adults 

 after transportation downstream as juveniles was 

 not seriously affected and survival was increased. 

 Throughout this study, we found no evidence of 

 straying among adults returning from the 

 experimental releases. All comparisons between 

 the adult returns from transported and control 

 groups of juvenile chinook salmon and steelhead 

 trout indicated that survival was definitely 

 increased by transporting juvenile fish to a release 

 site downstream from Bonneville Dam. 



We have been particularly concerned with how 



the percentage return from these experiments 

 might compare with that of unhandled or undis- 

 turbed juvenile migrants. Some insight into this 

 matter is shown by a comparison between es- 

 timated adult returns from juveniles marked and 

 released as controls and returns of unhandled 

 adult fish to Rapid River Hatchery in Idaho (Table 

 2); the data indicate that survival of chinook salm- 

 on released in our 1968 experiment was greater 

 than that indicated for salmon returning to the 

 Rapid River Hatchery. Adult returns from con- 

 trols released in 1969 were comparable to hatchery 

 returns, but returns from those released in 1970 

 were lower than returns to the hatchery. 



It is assumed that some stress was placed on 

 juveniles in the collection, handling, marking, and 

 transport processes. These cumulative stresses 

 were not outwardly apparent in the physical con- 

 dition of the juvenile smolts at the time of 

 handling, but differences in survival of returning 

 adults indicated that condition of the fish at the 

 time of marking must have varied among years. 



Our collection methods were changed in 1970 by 

 addition of a fish pump; this added a pumping 

 stress to our fish handling process. Although Park 

 and Farr (1972) indicate no immediate mortality 

 or observed stresses due to pumping from the 



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