of the days -out period of the two re- 

 covery groups were not statistically 

 different. 



Number of tag recoveries 



30 



Average number of days out 10.7 



Range of days out 7 to 16 



Since the distance between Rock Island 

 Dam and Zosel Dam is about 145 males, 

 the average rate of travel is 13.5 miles 

 per day. 



The results of a comparison of the 

 time of peak counts of blueback salmon 

 at Rock Island and Zosel Dams were 

 found to agree with results of the tagging 

 studies. In 1953 the mode at Rock 

 Island Dam occurred during the period 

 Jxily 15-22, with a maximum count on 

 July 18. At Zosel Dam the mode oc- 

 curred during the period July 23-30, 

 with the maximum noted on July 28. 

 Thus, the difference in time between 

 maximum counts (10 days) compares 

 closely with the 10.7 days travel time 

 established by tagging studies. Other 

 seasons could not be compared as no 

 definite peaks in abundance were noted 

 at Zosel Dam. 



DISTRIBUTION OF SPAWNERS IN 



TRIBUTARIES ABOVE ROCKY 



REACH DAM SITE 



Salmon are known to be attracted 

 to certain spawning areas in a river 

 system, if the flow, temperature, 

 gravel, and other requirements are 

 fulfilled. Normally, there is very little 

 straying from these spawning areas 

 from year to year. The purpose of the 

 investigation was to discover the spawn- 

 ing areas now used by salmon in the 

 tributaries above Rocky Reach Dam 

 site. 



Stream surveys were made to 

 determine the distribution and com- 

 parative abvmdance of spawners in the 

 tributary streeims. While the survey 

 counts do not represent the total num- 

 bers of spawners present, the counts 

 are of value in deternaining the dis- 

 tribution and coinparative abundance of 



spawners from year to year and indif- 

 ferent streams, providing the surveys 

 are made in the Seime manner. Aerial 

 surveys, of the number of salmon 

 nests were used as an add in locating 

 the area of spawning in the Okanogan 

 River from Oroville to Brewster. 



Tagging experiments atRock Island 

 Dam gave additional information about 

 spawning areas of the different seg- 

 ments of the runs which pass Rocky 

 Reach Dam site. Although these ex- 

 periments were designed for evaluating 

 the fishways, they also yield data which 

 are applicable to this study. Chinook 

 and blueback salmon were tagged 

 throughout most of their period of mi- 

 gration at Rock Island Dam during the 

 1954, 1955, and 1966 experiments. 

 Many tagged salmon were recovered 

 on the spawning grounds, and from 

 their distribution we learned which 

 spawning areas were used by various 

 segments of the run. 



Chinook salmon 



Peak counts of salmon and the time 

 period encompassing the peak of spawn- 

 ing are listed in table 2. These counts 

 serve to exemplify the relative im- 

 portance of each tributary stream- 

 Note the increased covmts in each 

 stream in 1957 over those of 1956. 

 Total counts of chinook salmon are 

 about 3 times the counts obtained in 

 1956. 



The distribution of fish within the 

 streams is illustrated in figures 5, 6, 

 and 7. The stream lengths have been 

 drawn to sccile; the widths, however, 

 have been exaggerated in order to show 

 areas of spawning. The symbols rep- 

 resent the comparative abundance of 

 individual species within each stream. 

 As observed, spring chinooks spawn 

 in the smaller tributaries and more 

 remote areas of the tributaries, and 

 summer chinooks in the larger main 

 tributaries. 



The distribution of spawning Chi- 

 nook salmon according to the time of 

 season they passed Rock Island Dam is 

 graphically illustrated by the recovery 

 of tagged fish on the spawning grounds. 

 The history of chinook salmon escape- 



