STATION NUMBERS 





 10 

 20 

 30 

 40 

 50 

 60 

 70 

 80 



10 12 14 16 18 20 



JULY 8-11 



16,18 20 



SEPTEMBER 3-6 



SEPTEMBER 30" 

 OCTOBER 1-3 



,8 10 12 14 16 16 20 



? . f , ^ 



NOVEMBER 4-8 



10 12 14 16 18 20 



FiouKE 6. — Continued 



measurements overlapped, the populations were 

 separated on the basis of marked fish in the catch. 

 By late May, however, the peak of migration from 

 the Weiser River had usually passed through the 

 reservoir. 



A comparison of the timing of peak catches in 

 the Snake River above the reservoir and at Brown- 

 lee Dam provided rough estimates of the time re- 

 quired for passage tlirough the reservoir — about 2 

 weeks in 1962 and 3 weeks in 1963 (fig. 8). Differ- 

 ences in flow and length of reservoir between the 

 2 years appear to account for the more rapid move- 

 ment in 1962. From early May through early 



June 1962 the reservoir was drawn down 9 m. and 

 was about 75 km. long. Over the same period in 

 1963 it was nearly full and 92 km. long (fig. 4). 

 Because of decreased depth and length in 1962, 

 the average movement of the water mass through 

 the reservoir was more rapid and conducive to 

 passage of fish. 



On the basis of the comparison of peak catches, 

 the movement through the reservoir of yearling 

 chinook salmon from tlie Weiser River averaged 

 6.4 km. per day in 1962 and 4.8 km. per day in 

 1963. Recapture of 334 marked individuals in 1962 

 and 1963 indicated that these fish moved through 



JUVENILE SALMON DISTRIBUTION AND MOVEMENT IN BROWNLBB RESERVOIR 



227 



