Figure 21. — Experimental arrarjgement for examining reactions of salmon fingerlings. 

 to overfalls and orifices. Approach cfiannel is 24 feet wide and 15 feet deep. 

 Release box may be seen at tfie far end of tfie clianncl. Inclined plane screen 

 trap is visible in tfie foreground. 



GENERAL OBSERVATIONS 



The effect of human odors on fish behavior lias 

 been quite conspicuous durinjij hiboratory experi- 

 ments. Fish near the surface rapidly sounded on 

 detecting the odor and activity was suppressed for 

 as long as 20 niiiuites. This re-emphasizes tluit in 

 the operation of fishways, effort should be made to 

 avoid physical contact with equipment that will 

 he immersed in the water. 



Fish movement through auxiliary pools and 

 channels can be exjx'dited by restricting these 

 channels to less than 4 feet of depth. The tendency 

 for salmon to linger and accumulate in deeper pools 

 and chaiuicls at the laboratory was efiVctively 

 discouraged by the use of wire-mesh grills at 

 shallow depths. 



Figure 22. — Ice Harbor prototype fisliway witf) 1-on- 

 10 slope now undergoing tests at Bonneville labora- 

 tory. Temporary divider walls liave been inserted 

 in eacli pool. Note paired orifices in eocli weir. 

 Large numbers of fish use these ports in ascending 

 the fishway. 



i 





14 



