EBEL: TRANSPORTATION OF CHINOOK SALMON AND STEELHEAD SMOLTS 



in 1972; average tag loss for the 3 yr of marking 

 was 3.79c. Release totals were adjusted for initial 

 tag loss. Additional tag loss (occurring after initial 

 tag loss), based on examination of 884 marked 

 adult steelhead at Dworshak National Fish 

 Hatchery and 154 marked adult chinook salmon 

 at Rapid River Fish Hatchery, was nill (<0.1%) 

 and did not affect data analysis. 



About 4-8^^ of the juvenile chinook salmon and 

 4-109^ (Park et al."^) of the juvenile steelhead re- 

 leased as controls were recaptured and released at 

 Little Goose Dam. No attempt was made to adjust 

 the data for a small bias that might have occurred 

 from this procedure. It was assumed that survival 

 of this portion of the controls that were handled 

 and released after passing through the collection 

 system was the same or greater than survival of 

 the majority of the control fish that had to pass 

 either through the turbines or over the spillway. 



The primary recovery site for evaluation of tag 

 returns was at Little Goose Dam where an au- 

 tomatic tag detector and fish trap were installed 

 (Ebel 1974). The efficiency of the detector and trap 

 was based on a comparison of known recovery of 

 fish with magnetized wire tags at Little Goose 

 Dam and subsequent recovery of these and other 

 marked fish at Rapid River and Dworshak Hatch- 

 eries. For example, 54 fish were identified at Rapid 

 River Hatchery in 1975 from treatment groups 

 that had passed Little Goose Dam. Of these, 50 had 

 jaw tags indicating they had been captured and 

 identified at Little Goose Dam; 4 did not have jaw 

 tags indicating these fish had passed the dam 

 without being trapped or identified. The trap ef- 

 ficiency for chinook salmon in 1975 was therefore 

 50/54 or 0.92. Thus, a factor of 1.08 was used to 

 expand recoveries of .2- and .3-age^ chinook salm- 

 on captured and identified at Little Goose Dam 

 in 1975 from experimental releases in 1972 and 

 1973. Similar calculations were made for each 

 year of recovery of chinook salmon during 1972-76 

 in computing estimated percentage return for a 

 particular treatment group. The same procedure 

 was used to estimate trap efficiency for steelhead 



'Park, D. L., J. R. Smith, E. Slatick, G. Matthews, L. R. 

 Basham, and G. A. Swan. 1978. Evaluation offish protective 

 facilities at Little Goose and Lower Granite Dams and review of 

 mass transportation activities, 1977. Northwest and Alaska 

 Fisheries Center, Natl. Mar. Fish. Serv., NOAA, 2725 Montlake 

 Boulevard East, Seattle, WA 98112. (Contract DACW68-77- 

 0043, Report to U.S. Army Corps of Engineers, Portland, Oreg.) 



*Age designations follow the formulas of Koo ( 1962). The 

 number of winters at sea is shown by an Arabic numeral pre- 

 ceded by a dot. 



with data obtained from recoveries at Dworshak 

 Hatchery. The efficiency of recovery varied among 

 years from 43 to 90^^ during the spring and sum- 

 mer when tagged chinook salmon were recovered. 

 One source of variation was due to periodic shut- 

 downs of the detector and trap for special studies of 

 passage of adult fish. The efficiency remained con- 

 stant (72'7f ) during the fall of each year when most 

 adult steelhead were recovered. An examination 

 of the timing of test and control fish returning to 

 Little Goose Dam indicated there was no sig- 

 nificant difference. Thus, variations in efficiency 

 did not affect comparisons of recoveries of test and 

 control fish because all experimental groups 

 passed the detector throughout the recovery 

 period, and both test and control groups were sub- 

 jected to the same variations in recovery ef- 

 ficiency. Total estimates of adult returns were ad- 

 justed for detector efficiency for a given period of 

 recovery. 



The use of the above method of estimating total 

 percentage return for treatment groups assumes: 

 loss of jaw tags from fish identified at Little Goose 

 Dam was nil and jaw-tagged fish survived at the 

 same rate as fish not jaw tagged. The first assump- 

 tion is valid, I believe, because examination of 

 several hundred fish at both Dworshak and Rapid 

 River Hatcheries each year of recovery did not 

 reveal any evidence of lost tags. Data from recent 

 radio tracking studies (see Monan and Liscom^) 

 suggest that the second assumption is also valid. 

 In these studies, adult chinook salmon were ob- 

 tained from the fish ladder with a similar trap and 

 handled in an identical manner before tagging, 

 and mortality of tagged fish was nil. 



Transport mortality was defined as the mortal- 

 ity which occurred as a result of handling, mark- 

 ing, and hauling; delayed mortality was consid- 

 ered mortality that occurred in samples held at 

 Bonneville Dam immediately after hauling. 

 Transport mortality of both species was <l9c of 

 the total number of smolts handled (Table 2). De- 

 layed mortality (Table 3) was considerably more, 

 ranging from 10to229J^ for chinook salmon and 1.0 

 to 4.5% for steelhead. Transport and delayed mor- 

 tality obviously reduced the total number of 



''Monan, G. E., and K. L. Liscom. 1974. Radio-tracking of 

 spring chinook salmon to determine effect of spillway deflectors 

 on passage at Lower Monumental Dam, 1973. Northwest and 

 Alaska Fisheries Center, Natl. Mar. Fish. Serv., NOAA, 2725 

 Montlake Boulevard East, Seattle, WA 98112. (Contract 

 DACW57-73-F-0534, Final Report to U.S. Army Corps of En- 

 gineers, Portland, Oreg.) 



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