screen which diverted fish down a flume and 

 into a live box was installed in the bypass. 

 Fish were counted individually or by weigh- 

 ing technique depending on the number pre- 

 sent. Scimples were taken for measuring and 

 scales were taken for age analysis. The 

 trapping device is illustrated in figure 9. 



Fishing effort was not constant during 

 the season. Trapping in the bypass had to 

 be discontinued during flood periods which 

 lasted from the middle of May to early July. 

 Also varying proportions of river flow were 

 diverted for power purposes. At times of 

 high flows only a small proportion of the 

 river was diverted and screened for young 

 fish. As the river dropped during the sum- 

 mer and fall months correspondingly higher 

 proportions of the river were diverted and 

 screened for young fish. In general, there- 

 fore, during spring months, saraplimg was of 

 only a small portion of the river, and dur- 

 ing summer and fall months a much greater 

 part of the river was sampled. 



Most fish were observed to pass during 

 the hours of darkness. Therefore, during 

 the spring period of sampling when the trap 

 required constant attention, counts were 

 taken hourly from 7 p.m. to 12p.m. or 1 a.m. 

 or until the number of migrants became very 

 few. Later, during the summer and fall 

 months, counts were taken in the evenings 



and mornings, giving data on day and night 

 migrations. Sampling at this station in 

 1955 continued from April 19 to November 13, 

 when the belt screens were removed just 

 prior to freeze-up. 



Trapping was initiated earlier in 1956 

 to determine, if possible, the beginning of 

 migration. As the diverting belt screens 

 were not put into operation until late in 

 April, fyke nets were fished in the river 

 near Tumwater Dam. The bypass trap was 

 operated as soon as the screens were in- 

 stalled, and fished until autumn. 



The penstock tube sustained numerous 

 breaks during the winter of 1955-56 and sub- 

 sequently, generation of power ceased and 

 the tube was closed. Attraction to the tube 

 side of the river and to the fish screens 

 was reduced and few catches were made in the 

 bypass trap. To augment migrant catches from 

 the Wenatchee River, fyke nets and floating 

 scoop-type traps were employed. The scoop- 

 type trap is pictured in figure 10. These 

 traps constituted the main fishing effort 

 during the summer months of 195 6. 



Two other streams were sampled for down- 

 stream migrants as time permitted during the 

 season. These streams were the Chiwawa River 

 and Nason Creek, both entering the Wenatchee 

 River some distance above Tumwater Dam. 



Figure 10. --Scoop-type migrant trap used for capturing young fish in the Wenatchee 

 River. (Design and plans coxirtesy Washington Department of Fisheries) 



