Figure 1. — Map showing trapping site below Oxbow JJam, 

 release sites in and altove Brownlee Reservoir, weir site, 

 and main spawning area of fall-run cliinook salmon in the 

 Snake River, 1960-62. 



In 1961, fish were collected in the trap until 

 numbers were sufficient for tagging. The trap- 

 ping time ranged from a few hours, soon after 

 the peak of the run (when the tests started), 

 to 1 day in the later stages of the run. In 1962, 

 the trapping to obtain fish for tagging and re- 

 lease was scheduled by stage of migration. In 

 the early and late stages (August 20 to Sep- 

 tember 23 and October 15-21) fish were col- 

 lected for 24 hours before they were removed 

 to the tagging area, and during the peak of 

 migration (September 24 to October 14) fish 

 were removed from the trap for tagging after 

 about 30 had accumulated. 



Fish were transported in a tank truck (3,785- 

 liter capacity) ; water was recirculated and, 

 except for a few hauls in 1960, oxygenated. 

 Ice was used to control water temperatures 



during the 3V2-hour drive to the release site at 

 the river, but not during the 1-hour drive to 

 the release site at the reservoir. 



All salmon were anesthetized (with tricaine 

 methane sulfonate) for tagging in 1961-62, 

 but not in 1960; none were anesthetized during 

 transportation. 



Prophylactic treatments, supervised by the 

 Fish Commission of Oregon, were used in 1962 

 to attempt to minimize the transmission of dis- 

 ease among fish during tagging and close con- 

 finement in the tank trucks. Prophylactics 

 included tincture of iodine, roccal, ethanol, and 

 malachite green. Tagging equipment was ster- 

 ilized in a 70 percent solution of ethanol ; the 

 tagging area on the fish was treated with 

 iodine. Wounds, abrasions, and infected areas 

 were treated by topical application of a 15 per- 

 cent solution of malachite green. In addition, 

 all fish were treated for 1 hour with 1 p.p.m. 

 (parts per million) of malachite green while 

 being transported to the release sites. At the 

 end of a day's operation, fish tanks on the 

 hauling trucks were sterilized with roccal. 



Skin discoloration and formation of blisters 

 early in the experiment indicated that the io- 

 dine treatment might be affecting the fish ad- 

 versely. As a precautionary measure, a 15 

 percent solution of malachite green was used 

 in lieu of the iodine after the third week of 

 tagging. On one occasion the fish tank was 

 inadequately rinsed and the remaining roccal 

 killed a load of fish. Thereafter malachite 

 green at a concentration of 2 p.p.m. was used 

 instead of roccal for sterilization. 



TAGGING AND KELEASE 



Petersen disk tags, sonic tags, and adipose 

 fin-clips were used to mark adult chinook sal- 

 mon before they were released. Personnel of 

 the Idaho Fish and Game Department applied 

 all disk tags (fig. 2), which were numbered or 

 multicolored for iderrtifying individual fish. 

 The Bureau of Commercial Fisheries attached 

 all sonic tags; only fish over 61 cm. were 

 tagged. The Bureau also excised the adipose 

 fins. 



CHINOOK SALMON PASSAGE THROUGH BROWNLEE RESERVOIR 



37 



