Table 6. — Estimated numbers of adult fall chinook 



egg potential of salmon spawning naturally in 



tributary to Bonneville Dam pool area, 



salmon and calculated 

 hatchery streams 

 1%5-60.1/ 



1/ Sex ratios of estimated natural spawners calculated from hatchery 

 data and rounded to nearest 100. Figures for estimated egg potential 

 rounded to nearest 1,000. 



2/ Egg potential based on 5,000 per female. 



3/ Period covered, 1955-60. 



4/ Years of data, 1946, 1950, and 1952. 



personnel conducted spawn-taking operations 

 on Eagle Creek and transferred the eggs to 

 that station. With exception of a release of 

 81,400 fish in 1949, no other fry or fingerlings 

 were returned to Eagle Creek from Bonneville 

 Hatchery. In its first 3 years of operation 

 Cascade Hatchery handled nearly 10,200 adults 

 (table 4). Since 1958 approximately 10,913,000 

 fry and fingerlings have been released from 

 Cascade Hatchery into Eagle Creek (table 5). 



Estimates of number of fish allowed to spawn 

 naturally in Eagle Creek are given in table 6. 



The stream is definitely limited for natural 

 reproduction with an impassable falls one mile 

 above the mouth. 



Bonneville Hatchery, Oregon 



For many years the source of eggs for 

 Bonneville Hatchery, located immediately 



downstream from Bonneville Dam, came from 

 fall Chinook salmon trapped at the rack on 

 nearby Eagle Creek. The eggs were incubated 

 in the hatchery, and the young fish released 

 into Tanner Creek, which is a source of water 

 supply for Bonneville Hatchery. 



Adult salmon in Tanner Creek were normally 

 handled about the same time as at Eagle Creek, 

 and the egg collections were combined. No 

 attempt was made to maintain identity of the 

 stocks. For this reason it is not possible 

 today to determine the size of the former runs 

 into Eagle Creek. 



NATURAL SPAWNING 



Natural spawning of fall chinook salmon in 

 tributaries to Bonneville pool is believed con- 

 fined primarily to Wind, Little White Salmon, 



11 



