INTRODUCTION 



The U.S. Fish and Wildlife Service is engaged in research to develop a method 

 of electrically guiding or directing downstream -migrating salmon fingerlings into by- 

 passes away from areas of high mortality. Many fingerlings are injured or killed each 

 year in spillways and turbines of large dams or are swept into irrigation diversions. 

 The mechanical screening used at small installations is generally considered im- 

 practical where huge volumes of water are involved. 



This research program includes experiments which range from large-scale 

 field trials to the seeking of basic information on the electrical characteristics and 

 energy levels effective in controlling the movements of salmon fingerlings (Collins, 

 Volz, and Lander, unpublished manuscript) and the relation of these to the electrical 

 characteristics and energy levels injurious to the fingerlings (Collins, Volz, and 

 Trefethen, 1954). 



The present research, an intermediate step between basic laboratory experi- 

 ments and full-scale field trials, was designed to test the effectiveness of one type 

 of a narrow direct current field in diverting salmon fingerlings in flowing water in 

 relation to the following factors: 



(1) The angle of the electrical field relative to the direction of 

 water flow . 



(2) The width of tlie electrical field. (Distance between row of 

 electrodes) . 



(3) The spacing between electrodes. 



(4) The diameter of electrodes . 



METHODS AND MATERIALS 



The experiments were conducted in a large concrete tank 24 feet wide and 30 feet 

 long, with a maximum depth of 16 inches . A coat of insulating paint was applied to the 

 inside of the tank to prevent distortion of the electrical field. The water level was 

 maintained at 9 inches and circulation of the v/ater during the experiments was main- 

 tained by a recirculating pump. Plywood vanes and a plywood island were used as aids 

 In Keeping a relatively uniform flow of water through the experimental area which was 

 approximately 18 feet long and 10 feet wide (fig. 1). 



