as it applies to all years, we shall use fish counts and 

 water temperatures along the migration route for 

 1937, 1944, 1952-54, 1962, and 1963 (table 6 and 

 figs. 8-10). For years when sockeye salmon were 

 tagged (1953, 1954, 19G2, and 1963), we will re- 

 examine as part of the analysis the tagging data in 

 figures 5 and 6. 



Although the data, particularly the fish counts 

 at Zosel Dam, are not precise enough for us to make 





85 - 

 . '5 - 

 -65 - 



55I: 



M^ 



20 30 10 20 30 



'^y^- 



10 20 30 10 20 30 

 JULf AUGUST 



10 20 30 10 20 30 

 JULY AUGUST 



10 20 30 10 20 30 



Figure 10. — Numbers of sockeye salmon counted at Rock 

 Island, Rocky Reach, and Zo?el Dams in 1962 and 1963. 

 -Average temperatures of the Okanogan (dotted line) and 

 Columbia (solid line) Rivers are given in the second panel 

 from the top. 



Figure 8. — Number of sockej-e salmon counted at Rock 

 Island and Zosel Dams, July and August, 1937 and 1944. 

 Average temperatures of the Okanogan (dotted line) and 

 Columbia (solid line) Rivers are given in the middle panel. 



Figure 9. — Number of sockeye .salmon counted at Rock 

 Island and Zosel Dams, July and August, 1952, 1953, and 

 1954. Average temperatures of the Okanogan (dotted 

 line) and Columbia (solid line) Rivers are given in the 

 middle panel. 



a ciuantitative analysis of the relations invoh^ed, we 

 do have evidence pertinent to our hypothesis that 

 imfa\orable water temperatiue (or related factors) 

 blocks the sockeye salmon from the Okanogan River 

 until falling temperatures allow the migration to 

 continue. 



Figures 8 to 10 establish clearly the general 

 relation between temperatiu'e and movement of fish 

 in the Okanogan River. When fish are presumably 

 available to the river, highs and lows in the count at 

 Zosel Dam not evident in the counts at Rock Island 

 Dam or Rocky Reach Dam, regularly follow falling 

 and rising temperature in the Okanogan River. 

 This relation is particularly striking when the tem- 

 perature drop is precedeti In' prolonged high tem- 

 peratures. Xo influence of the temperature of the 

 Columbia River on the upstream migration of 

 sockeye salmon is apparent. 



Knowledge of the normal travel time from Rock 

 Island Dam to Zosel Dam under favorable tem- 

 perature conditions is highly relevant to an under- 

 standing of the effects of unfavorable temperatures 



MIGRATIOX OF SOCKEYE SALMON 



141 



