FISHERY BULLETIN: VOL. 78, NO. 2 



transported a shorter distance. Secondary objec- 

 tives were: to determine any relation between tim- 

 ing of downstream juvenile migrants and timing 

 of subsequent adult returns and to determine 

 whether size and ocean age of adults (transported 

 as smolts) were affected by the collection and 

 transport process. The results of the experiments 

 described in this report are also compared with the 

 preliminary results of the current experiment at 

 Lower Granite Dam. 



BACKGROUND 



The changes in abundance and the causes of 

 changes in abundance of individual salmonid 

 populations in the Columbia River drainage have 

 been summarized by Chaney and Perry (1976). 

 Raymond^ analyzed the trends in abundance of 

 Snake River runs in detail and clearly showed that 

 the major causes of the decline of the Snake River 

 stocks are due to the losses of juveniles during 

 their seaward migration. These losses are caused 

 by injury or death occuring when the fish attempt 

 to pass the eight dams and reservoirs placed in 

 their migratory path. These dams now inundate 

 over 630 km of the migratory route. The main 

 causes of the juvenile losses have been attributed 

 to: passage through turbines (Bell et al. ; Long, 

 Krcma, and Ossiander ; Long, Ossiander, Ruehle, 

 and Mathews^); supersaturation of river water 

 with atmospheric gas (Ebel and Raymond 1976); 

 delay in migration (Raymond 1968, 1969); and 

 increased predation (Chaney and Perry 1976). 



^Raymond, H. L. 1975. Snake River runs of salmon and 

 steelhead trout: trends in abundance of adults and downstream 

 survival of juveniles. Unpubl. manuscr., 11 p. Northwest and 

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

 Montlake Boulevard East, Seattle, WA 98112. 



3Bell, M. C, A. C. DeLacy, G. J. Paulik, and R. A. Win- 

 nor. 1967. A compendium on the success of passage of small 

 fish through turbines. Northwest and Alaska Fisheries Center, 

 Natl. Mar. Fish. Serv., NOAA, 2725 Montlake Boulevard East, 

 Seattle, WA 98112. (Contract DA-35-026-CIVENG-66-16, Re- 

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



*Long, C. W., R. F. Krcma, and F. J. Ossiander. 1968. Re- 

 search on fingerling mortality in Kaplan turbines — 

 1968. Unpubl. manuscr., 7 p. Northwest and Alaska Fisheries 

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

 Boulevard East, Seattle, WA 98112. 



*Long, C. W., F. J. Ossiander, T. E. Ruehle, and G. M. Mat- 

 thews. 1975. Final report on survival of coho salmon fingerlings 

 passing through operating turbines with and without perforated 

 bulkheads and of steelhead trout fingerlings passing through 

 spillways with and without a flow deflector. Northwest and 

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

 Montlake Boulevard East, Seattle, WA 98112. (Contract 

 DACW68-74C-0113, Report to U.S. Army Corps of Engineers, 

 Portland, Oreg.) 



492 



The National Marine Fisheries Service (NMFS) 

 has been conducting transportation experiments 

 since 1965 in an attempt to find ways of reducing 

 these losses. The first study where natually mi- 

 grating juveniles were collected and transported 

 was conducted by Ebel et al. (1973). This study 

 showed that the homing ability of adult spring and 

 summer chinook salmon and steelhead captured 

 during their seaward migration as juveniles and 

 then transported downstream (from Ice Harbor 

 Dam to below Bonneville Dam) was not di- 

 minished. Data based on returning adults indi- 

 cated that survival rate of adult fish that had been 

 transported as juveniles increased 1.5-3 times the 

 survival rate of those not transported, depending 

 on environmental conditions in the river during 

 the time of transport. Studies conducted prior to 

 this study with hatchery stocks of salmonids 

 showed that the majority of the adult fish that had 

 been transported as juveniles returned to the re- 

 lease site, not to the parent location (Snyder 1928; 

 Ellis and Noble 1960). Obviously, juvenile salmo- 

 nids captured during their seaward migration 

 and then transported differed in their responses 

 from fish transported directly from hatcheries. 

 The wild and hatchery stocks captured in the ex- 

 periment conducted by Ebel et al. (1973) were 

 smolting and had traversed several hundred 

 kilometers before capture. These may be the main 

 factors causing the different response (homing 

 ability was not diminished) obtained in the exper- 

 iment done in 1973. 



Previous experiments (Hasler and Wisby 1951; 

 Groves et al. 1968; Scholz et al. 1973) on 

 mechanisms used by fish for homing indicated 

 that the experience prior to and during the time 

 that a juvenile salmon migrates is important in 

 enabling the fish to receive visual and olfactory 

 cues necessary for homing as an adult. 



Only a portion of the migration route was elimi- 

 nated by transporting the fish from Ice Harbor 

 Dam to The Dalles and Bonneville Dams. Elimi- 

 nation of this portion of the migratory route appar- 

 ently did not seriously affect the ability of either 

 the chinook salmon or steelhead to home. How- 

 ever, the length of the migration route or amount 

 of homing cues that can be eliminated and still 

 achieve satisfactory homing is unknown. 



The success of the experiment by Ebel et al. 

 (1973) at Ice Harbor Dam encouraged the NMFS 

 to begin a similar experiment at Little Goose Dam 

 in 1971. As this dam is approximately 130 km 

 upstream from Ice Harbor Dam, an additional 130 



