the inclined-screen trap. Tests to determine the 

 exact time involved in this delay were not conclu- 

 sive but indicated that the delay was usually less 

 than 4 hours and often even less than 1. Although 

 the array trap was checked every 2 hours and the 

 inclined-screen trap every 4, we computed the fish- 

 guiding and collecting efficiencies by gi'ouping the 

 fish captured in each trap during a 24-hour period 

 and then comparing these totals. 



Table 6. — Adjusted fish-guiding efficiency (in percent) of 

 the electrode array (power on) , without the array trap, for 

 each water velocity, test period, and fish species 



Consequently, the delay time due to the distance 

 between the two traps affected only the data for 

 tlie last inclined-screen trap catch in each 24-hour 

 period. Therefore, no lag time was allowed in 

 computing any of the fish-collecting efficiencies. 

 The total number of fish captured in the array trap 

 from 12 :00 midnight to the following 12 :00 mid- 

 night was compared with the total number of fish 

 captured in the inclined-screen trap during the 

 same period. When we analyzed the data to allow 

 for a 4-hour delay (comparing catches in the array 

 trap between 12:00 midnight and the following 

 12:00 midnight with catches in the inclined-screen 

 trap between 4:00 a.m. and the following 4:00 

 a.m.) and an 8-hour delay (comparing catches in 

 the array trap between 12 :00 midnight and the 

 following 12 :00 midnight with catches in the 

 inclined-screen trap between 8 :00 a.m. and the fol- 

 lowing 8:00 a.m.), the results did not modify our 

 major conclusions. 



CONCLUSIONS 



We have two major conclusions : 



1. The fish-guiding efficiency of the electrical 

 system generally decreased as water velocity in- 

 creased, probably because juvenile salmon and 

 trout may be progressively less able to control their 

 movements as velocity increases. 



2. The use of electricity to guide juvenile salmon 

 and trout migrating downstream may be feasible 

 in certain environments where the water velocity 

 does not exceed 0.3 in.p.s., but does not appear 

 practical for use in most rivers and streams. 



ACKNOWLEDGMENTS 



The Bureau of Keclamation allowed us to use 

 the Chandler Canal near Prosser, Wash., as our ex- 

 perimental site. The Washington State Depart- 

 ments of Fisheries and Game cooperated by 

 permitting us to experiment on natural, down- 

 stream migrating fish of the Yakima River system. 

 Winston Farr designed the velocity control and 

 fish-capturing facilities, and Holbrook L. Garrett 

 designed and supervised the construction of the 

 electrode array. William S. Davis, Jr., planned the 

 experimental design, and Charles C. Gillaspie 

 constructed the electrical equipment and was 

 responsible for its operation and maintenance. 



LITERATURE CITED 



Andrew, F. J., L. R. Kersey, and P. C. Johnson. 



1955. An investigation of the problem of guiding 

 downstream-migrant salmon at dams. Int. Pac. 

 Salmon Pish. Comm., Bull. 8, 65 pp. 

 Bates, Daniel W., and Russell Vinsonhaler. 



1957. Use of louvers for guiding fish. Trans. Amer. 

 Fish. Soc. 86 : 38-57. 



Brett, J. R., and D. F. Alderdice. 



1958. Research on guiding young salmon at two 

 British Columbia field stations. Fish. Res. Bd. 

 Can., Bull. 117,75 pp. 



DuBKiN, Joseph T., Donn L. Park, and Robert F. 

 Raleigh. 

 1970. Distribution and movement of juvenile salmon 

 in Brownlee Reservoir, 1962-65. U.S. Fish Wildl. 

 Serv., Fish. Bull. 68 : 219-243. 

 Haskell, David C, John MaoDougal, and Donald 

 Geduldig. 

 1954. Reactions and motion of fish in a direct current 

 electric field. N.Y. Pish Game J. 1(1) : 47-64. 



FISH-GUIDING EFFICIENCY OF AN ELECTRICAL GUIDING SYSTEM 



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