1964 



Rainbow Trout 



Anadromous rainbow trout spawned in the same 

 tributaries as spring chinook salmon. Offspring of 

 the anadromous form could not be separated from 

 resident native and planted rainbow trout that 

 complete their life cycle in fresh water. Studies 

 on the enti-y of trout into the reservoir included 

 young from all three groups. 



Table 5. — Lengths of juvenile kokanee salmon during 

 migration past sampling site in Snake River, 1963-66 



Figure 7. — Timing of migration of kokanee salmon 

 from tbe Snake River to Brownlee Reservoir, 

 1964-65. 



' First week. 

 - Last week. 

 ' Insufficient sample. 



Trout migrated from the Snake River in the 

 spring (fig. 8) at the same time as the chinook 

 salmon i:)opulations. Time of peak migration 

 varied but was in late April or May 1962-65. Age 

 groups were from O to IV, but most were age- 

 group I and II. Size overlap was considerable 

 among age-groups I and II. Table 6 shows the age 

 groups and length-frequency ranges for 1963. 



The movement of rainbow trout from Eagle 

 Creek (fig. 9) also took place primarily in the 

 spring; about 75 percent of the fish migrated in 

 late spring, at a time of high flows. A smaller run 

 peaked in the fall. Fish of age-groups I and II 

 dominated the run in the spring. Age-groups O 

 and I were dominant in the fall ; however, all age- 

 groups O through IV were represented. Table 7 

 shows the size ranges. 



MIGRATIONS OF HATCHERY-REARED SALMON 



Most of the chinook salmon spawners were di- 

 verted to hatcheries from 1963 through 1965. In 

 1964 and 1965, hatchery-reared fingerling salmon 

 were released at the Snake Eiver spawning area, 

 88 to 120 km. above the reservoir. Chinook salmon 

 fingerlings from fall migrating adults were re- 

 leased in 1964 and 1965. Coho salmon fingerlings 

 were released in 1964 and sockeye salmon finger- 

 lings in 1965. 



210 



U.S. FISH AND WILDLIFE SERVICE 



