RATES OF MIGRATION OF FISH 

 MARKED WITH PETERSEN TAGS 



The rate of movement of chinook salmon in 

 Brownlee Reservoir in 1960 was estimated by 

 Hauck (see footnote 1) from tagged fish that 

 sport fishermen recovered on the spawning 

 grounds. Eight fish released in the reservoir 

 and five released in the river were recovered ; 

 the elapsed time from release to recovery aver- 

 aged 32.0 days (range, 17 to 42) for fish re- 

 leased in the reservoir and 25.8 days (range, 

 18 to 30) for those released in the river 16 km. 

 above the reservoir. On the basis of the dif- 

 ference between the averages (6.2 days) and 

 the distance between the reservoir and the river 

 release sites (104.5 km.), he estimated the av- 

 erage rate of movement in the reservoir as 16.8 

 km. per day. 



Rates of migration were not studied in 1961, 

 but in 1962 the rate of movement through the 

 reservoir was estimated from data on five 

 tagged fish that were identified as they mi- 

 grated through a gate in a weir in the Snake 

 River (fig. 6). The weir was 20 km. above the 

 reservoir and 1 km. above the river release site, 

 which was 19 km. above the reservoir in 1962. 

 (Midway through the experiment, it became 

 evident that the weir was delaying upstream 

 migration; the structure was removed at the 

 end of September to allow free passage of adult 



Figure 6. — Snake River weir (upstream view) with fish traps 

 for identification and release of migrating salmon. Site is 

 about 20 Ivm. above Brownlee Reservoir. 



migrants.) The total elapsed time between re- 

 lease of the five fish above Brownlee Dam and 

 recapture at the vveir (108.5 km. upstream) 

 ranged from 3.2 to 9.9 days and averaged 6.7 

 days. Thus, the average rate of upstream 

 movement from release to passage through the 

 weir was 16.1 km. per day. The true rate of 

 movement may have been somewhat faster 

 than indicated because the calculation does not 

 take into account any possible delays at the 

 weir. 



Thirteen tagged salmon released in the Snake 

 River in 1962 were observed passing through 

 the weir, 1 km. upstream, in elapsed time that 

 ranged from 2.2 hours to 6.6 days and averaged 

 2.8 days (or about 0.36 km. per day). The de- 

 laying effect of the weir undoubtedly accounted 

 for the low rate of movement in this stretch 

 of river. As is shown in the next section, 

 more than half of the sonic-tagged fish reached 

 the weir in less than 1 hour ; hence, they moved 

 up this short section of stream at about 19 km. 

 per day. 



ORIENTATION AND MOVEMENT 

 OF SONIC-TAGGED FISH 



Because the sonic tags we used transmitted 

 identifiable signals for only about 5 days, our 

 experiments were limited to a study of initial 

 behavior after release. In such a study, it is 

 essential that the attachment of the tag not 

 aflfect the behavior of the fish. We were un- 

 able to detect any immediate eff'ect of the tag 

 from visual observations of tagged and un- 

 tagged fish released in the same area. Al- 

 though the long-term effect on behavior is 

 unknown, previous work by the Bureau of 

 Commercial Fisheries during the past 10 years 

 suggests that the eflfect may be slight (Johnson, 

 1957). 



BROWNLEE RESERVOIR 



Most of the chinook salmon with sonic tags 

 released in Brownlee Reservoir in 1961 were 

 initially disoriented and spent considerable time 

 in the lower end of the reservoir before re- 

 suming migration upstream. The movement 



42 



U.S. FISH AND WILDLIFE SERVICE 



