CO 



480 p 

 440 - 

 400- 

 360- 

 320- 

 280- 



I I Unmarked fish 

 H Marked fish 



HOLDOVERS FROM SPRING MIGRATION 

 (MOSTLY SNAKE RIVER AGE-GROUP 0) 



FALL MIGRANTS FROM 

 EAGLE CREEK 



I I 1 — r 



80- 90- 

 84 94 



100- 110- 120- 130- 140 150- 160- 170- 180" 190- 200- 210" 220" 230- 240- 

 104 114 124 134 144 154 164 174 184 194 204 214 224 234 244 



LENGTH (MM.) 



FrouRE 9. — Len^hs of juvenile spring Chinook salmon from Eagle Greek that entered Brownlee Reservoir in the 

 fall and lengths of holdover Chinook salmon from populations that entered in the spring, in samples collected 

 September through December 1962. 



1963. We presume that some Eagle Creek fish 

 moved upreservoir in 1963 because of frequent up- 

 reservoir currents. The fish that arrived at the 

 upper end of the reservoir in late June and July 

 as the "smolting'' condition (Hoar, 1963; Conte, 

 Wagner, Fessler, and Gnose, 1966) was attenu- 

 ating and reservoir temperature and oxygen con- 

 ditions were deteriorating (figs. 6-7) may have 

 been attracted upstream by the relatively cooler, 

 oxygenated wat^r of tlie Snake River. 



FALL CHINOOK SALMON OF AGE-GROUP O 



Juvenile fall chinook salmon entered the reser- 

 voir as age-group O and at a smaller length (33- 

 105 mm.) than other ijopulations. They began their 

 migration from spawning grounds in the Snake 

 River about 120 km. above the reservoir. Table 2 

 gives estimates of fall chinook juvenile salmon that 

 entered the reservoir. 



We studied the offspring of native popidations 

 in 1962 and 1963; hatchery-reared juvenile fish 

 from otlier sources were released in the spawning 



area for study as they passed through the reservoir 

 in 1964 and 1965. 



Table 2. — Estimated numbers of fall chinook salmon that 

 entered Brownlee Reservoir, 1962-66 {from Krcma and 

 Raleigh, 1970) 



Year 



Native Hatchery- 

 reared 



Numbtr offith 



1962.. 629,000 (') 



1963 374,000 (') 



1964 (!) 111,600 



1965 (') 162,800 



' None released. 



' Negligible numbers. 



Juvenile native fall chinook salmon entered the 

 reservoir from late April through June in 1962 

 and from late April through mid-June in 1963. 

 Mean lengths of age-group O fish in the reservoir 

 were 56 to 85 mm. through the 1962 season and 75 

 to 195 mm. in 1963. 



Peak catches above the reservoir and at the 

 fingerling collection facility near Brownlee Dam 



JUVENILE SALMON DISTRIBUTION AND MOVEMENT IN BROWNLEE RESERVOIR 



231 



