had passed Tumwater before high waters of 

 the spring run-off occurred. During both 

 secisons blueback commenced their migration 

 as the river started to rise. Rising waters 

 of the early run-off in 1956 coincided with 

 the blueback migration, which may explain 

 the comparatively few fish trapped this sea- 

 son. Apparently fewer fish were attracted 

 to the water intake tube. 



Both Chinook and steelhead were migrat- 

 ing during this spring period of steadily 

 increasing flow and possibly commenced their 

 migration before the flows rose appreciably. 

 Although data are lacking, it is likely that 

 migration for these species continued during 

 the high water season. 



The counts of chinook and steelhead 

 obtained from July to November indicated a 

 ready movement in the river during months 

 when waters were falling steadily to low 

 levels. 



Pish Movements and Water Temperature 



Daily water teii5)eratures , taken by hand 

 thermometer during the period of migrant 

 sampling at Tumwater, are given in figure 18. 

 Chinook salmon were taken on April 2, 1956, 

 the first day of trapping, soon after the 

 upward trend of water temperatures started. 

 In 1956, the first blueback were taken the 

 25th of April or after temperatures had 

 reached approximately 40° F. In 1955 water 



5 10 15 20 25 



Figure I7. — Wenatchee River discharge at Plain, Washington. 



79-- 



70'- 



50«- 

 45* ■ 



40' ■ 

 3S^ . 



50» 



1955 

 1956 



\hr V W 



wT^^y^ 



S K) I5Z02S S 10 I9 20 2S 5 10 IS 20 25 5 tO 15 20 25 ' 5 10 15 20 29 ' 5 10 15 20 25 ' 5 10 15 20 25 ' 5 10 IS 20 25 ' 5 tO IS 20 25 ' 5 10 15 20 25 ' 5 O 15 20 29 



FEBRUARY MARCH APfllL 



AUGUST SEPTCwaEn OCTOBER NOVEMBER DECEMBER 



Figure l8. — Wenatchee River Water tenrperature at Tumwater Dam. (Hand thermometer) 



13 



