the total run passed through the fishways in 

 July, as compared to about 79 percent during 

 the same month in 1964. 



Coho, Oncorhynchus kisutch (Silver) 



The 1965 coho coxint of 258 was more than 

 three times the 32-yr. average of 80, and about 

 35 percent of the peak year of 737 in 1962 

 (table 1). The first coho was observed on 



August 17, 1965, as compared to September 1 1 

 in 1964. Maximum day's count of 27 occurred 

 on September 29 and October 7. Of the coho 

 passing the dam in 1965, about 84 percent used 

 the left ladder, while 3 and 13 percent used 

 the middle and right ladders, respectively 

 (table 7). In 1964, approximate percent use by 

 ladder was left, 80; middle, 2; and right, 18. 

 Additional data are shown in tables 2, 12- 

 14. 



Table 7. — Semimonthly number and percent of coho salmon counted over each ladder, Rock Island Dam, 



1965 



Steelhead, Salmo g airdneri 



The 1965 steelhead count of 6,063 was 73 

 percent greater thsin the 32-yr. average of 

 3,506. In 1965, greatest number of steelhead 

 passed through the fishways in September 

 when 2,204 were recorded (table 2). Peak 

 monthly movement of these fish in 1964 also 

 occurred in September when 1,688 were 

 counted. 



Of the steelhead passing Rock Islauid Dam 

 in 1965, about 83 percent used the left ladder, 

 while 7 and 10 percent ascended the middle 

 and right ladders, respectively (table 8). In 

 1964, approximate percent use by ladder was: 

 left, 76; middle, 10; and right, 14. Maximum 

 day's count in 1965 was 187 on October 7 

 (table 3), as compared to 129 on September 

 17, 1964. Additional data pertaining to the 

 movement of steelhead at Rock Island Dam 

 are contained in tables 9-14. 



