Figure 12. — ^Revolving drum screens used to divert fish tliat escaped past the electrode array to an inclined- 

 screen trap. 



array trap — {jercentage of fish actually guided by 

 the electrode array and the electrical field created 

 by the electrode array. Details of the methods used 

 to compute these fish-guiding and collecting effi- 

 ciencies are discussed below. 



ELECTRODE ARRAY ENERGIZED PLUS ARRAY 

 TRAP 



Table 3 shows the fish-collecting efficiency of 

 the electrode array and array trap with the power 

 on for each test velocity and test period, by fish 

 species. Tliese efficiencies (in percentages) were 

 computed by dividing the total number of each 

 species of fish captured in the electrode array trap 

 during a specific power-on period by the sum of 

 this nmnber plus the number of fish of the same 

 species captured in the inclined-screen evaluation 

 trap during the same power-on period, and multi- 

 plying the quotient by 100. 



The mean fish-collecting efficiency for the elec- 



Table 3. — Fish-collecting efficiency {in percent) of the 

 electrode array and array trap, with the electrode array 

 energized, for each water velocity, test period, and fish 

 species 



trode array and array trap with the power on was 

 highest at a water velocity of 0.2 m.p.s.; inter- 

 mediate at 0.8 m.p.s.; and lowest at 0.5 m.p.s. (fig. 



318 



U.S. FISH AND WILDLIFE SERVICE 



