Sockeye Salmon 



Counts of sockeye salmon at Rock Island 

 during the period of study varied from approxi- 

 mately 71,000 to 155,000 fish (fig. 3). The 

 timing of the runs was relatively constant 

 with the exception of 1959 when the run was 

 later. We suspect that the temporary fish 

 passage facilities in use at the time at Priest 

 Rapids Dam, then under construction 56 miles 

 below Rock Island Dam, caused a delay be- 

 cause the runs passed Bonneville and McNary 

 Danns (located downstreann from Rock Island) 

 at their usual times. 



Estimates of sockeye salmon passing Rocky 

 Reach damsite for the period 1954 through 

 1960 are given in table 2. The year 1960 was 

 the only one for which less than 50 percent 

 of the run was attributed to areas above 

 Rocky Reach dannsite. 



Steelhead 



The count of 6,226 steelhead in 1960 was 

 the highest recorded at Rock Island Dam 

 (fig. 4). From 1954-60 the counts varied 

 from 1,540 to 6,226 steelhead. The counts 

 are of fish passing fronn May to October 

 only. Periodic counts made during winter 

 have included nnigrating steelhead, but no 

 abundance estimates have been made. 



The spring and fall seasonal steelhead 

 counts are of fish destined to spawn in 2 

 calendar years. The steelhead spawning popu- 

 lation in any one spring is composed of fish 

 that passed Rock Island that spring and the 

 preceding winter and fall. Thus the counts 

 given in figure 4 represent two different 

 groups of spawners, the spring group spawn- 

 ing that same spring and in early summer and 

 the fall group spawning the following spring. 

 By rearranging the counts so as to represent 

 totals for a single year's spawning stock, we 

 have arrived at the following number of 

 spawners: 



Year 



Nunnber of steelhead 



1954-55 4.988 



1955-56 3,118 



1956-57 1,509 



1957-58 4,097 



1958-59 3,813 



1959-60 4,567 



1960-61 4,428 



Stocks for the different years were arbitrarily 

 separated on July 2; the counting period is 

 from May 1 to October 1 . 



No estimates were nnade of the number of 

 steelhead attributed to areas above Rocky 

 Reach. Sport fishery catches of this species 

 above Rocky Reach are evidence that they 



3 20 27 3 K) 17 24 I 

 August September 



Figure 3. — Weekly sockeye salmon counts at Rock Island 

 Dam, 1954-60. 



are found in the area. Because of high runoff 

 and turbid waters during the spring (May and 

 June) we were unable to determine the spawn- 

 ing areas and nnake estimates of spawners 

 within tributaries. 



Silver Salmon 



Seasonal counts of silver salmon at Rock 

 Island for the 7 years are not comparable, 

 because of different termination dates in 

 counting (table 3). 



No attempts were made to determine 

 the distribution or abundance of this species 

 above Rock Island Dam. 



