ing time, however, did not appear to be an 

 important factor in survival. Although fish 

 transported to the Snake River vi'ere confined 

 in a tank truck about 21/2 hours longer than 

 those transported to the reservoir, they ap- 

 peared to be in excellent condition at release. 

 Other investigators have also indicated that 

 prolonged transportation is not detrimental to 

 adult chinook salmon. Parker and Hanson 

 (1944) successfully transported adult salmon 

 for 2 hours, and Fish and Hanavan (1948) 

 reported hauls of about 4 hours without adverse 

 effects. Groves (personal communication') 

 transported adult chinook salmon for about 5 

 hours to a test area in 1961 and followed this 

 at a later date by a 5-hour return haul to a 

 hatchery. He reported no mortalities directly 

 attributable to the prolonged transportation. 



Differences in postrelease environment also 

 had no apparent effect on survival in the pres- 

 ent experiments. Differences between recover- 

 ies of tagged fish released in the reservoir and 

 of those released in the river were not signifi- 

 cant in any year (table 2) . 



Table 2. — Numbers of marked and unmarked faU-run chinook 



salmon released in Rrownlee Reservoir and the Snake River 



and numbers recovered on the spawning grounds, 1960~€2 



1962 

 Reservoir 



River 



13 

 31 

 85 

 11 



2.9 



8.5 



24.9 



3.2 



^ Tag indicates Petersen disk; none of the 59 fish tagged with sonic tags 

 were recovered. 



2 Hauck, Forrest. 1961. Fall chinook salmon tagging studies. Snake 

 River. 1960. Idaho Fish and Game Department. 7 pp. [Processed.] 



3 Graban. James R. 1964. Evaluation of fish facilities. Brownlee and 

 Oxbow Dams, Snake River. Idaho Fish and Game Dept. 60 pp. [Processed.] 



The effect of tagging on survival of fish re- 

 leased in the reservoir apparently varied in 



different years. In 1960, the percentages of 

 tagged and untagged fish recovered in the 

 spawning areas were closely similar; in 1961, 

 more untagged than tagged fish were recov- 

 ered; and in 1962 the pei'centage recovery was 

 higher for untagged fish than for either fin- 

 clipped or tagged fish, and higher for fin-clipped 

 than for tagged fish (table 2). 



A high mortality of tagged fish was apparent 

 in the early phase of the 1962 experiment. No 

 recoveries were made of tagged fish released in 

 the reservoir or in the Snake River during the 

 first 4 weeks of tagging, August 27 to Septem- 

 ber 23 (table 3), and only one recovery was 

 made from fish released in the first 5 days of 

 the following week of tagging. This lack of 

 tag recoveries coincided with a period of sus- 

 tained high water temperature at both release 

 sites. The average temperature of surface 

 water was 22.1° C. (range, 21.1° to 23.9°) in 

 Brownlee Re.servoir and 18.4° C. (range, 16.6° 

 to 20.6°) in the Snake River. 



Table 3. — IVuiiihers of tagged fall-run chinook salmon recovered 



on the spawnitig grounds after release above BroicnJee Dam 



in 1963, bi/ week of release 



Week of 

 release 



Fish 

 released 



Fish 

 recovered 



spawnmg 

 grounds 



Fish 

 released 



Fish 

 recovered 

 in on_ 



river spawning 



grounds 



Number 



Number 





 

 

 

 2 

 7 

 3 

 1 



Number 



7 

 29 

 31 

 85 

 46 

 80 

 41 

 21 



Number 





 

 





 3 



».\lan B. Groves. 1963. Fishery Biologist. Biological Laboratory, 

 Bureau of Commercial Fisheries, Seattle, Wash. 



The high temperature, however, apparently 

 was not the direct cause of mortality. The 

 good recovery of untagged fish in 1962 (highest 

 of the .3 years) suggests that a fair number of 

 untagged fish from the early releases must have 

 survived and reached the spawning grounds in 

 spite of the high water temperatures. Possibly 

 the additional stress on fish during handling, 

 anesthetizing, and tagging produced the 

 mortalities. 



Mortality from tagging was also indicated 

 in 1961 by the diflferences in percentage recov- 



40 



U.S. FISH .WD WILDLIFE SERVICE 



