EFFECT OF WATER VELOCITY ON THE FISH-GUIDING EFFICIENCY OF 



AN ELECTRICAL GUIDING SYSTEM 



BY JOHN R. PUGH, GERALD E. MONAN, AND JIM R. SMITH, FISHERY BIOLOGISTS 



BUREAU OF COMMERCIAL FISHERIES BIOLOGICAL LABORATORY 



SEATTLE, WASH. 98102 



The study was performed in 1962 in a diversion of 

 tlie Yakima River near Prosser, Wash. Massive struc- 

 tures for regulating the water velocity, producing the 

 desired electrical field, and collecting the guided fish 

 were installed. Evaluation facilities consisted of rotary 

 drum screens to divert all fish that escaped past the 

 electrical field to an inclined-screen trap. The fish tested 

 were wild, downstream-migrating fingerlings of Chi- 

 nook salmon, Oncorhynchus tshawytscha; coho salm- 

 on, O. kisutch; and rainbow or steelhead trout, Salmo 

 gairdneri. The variables were three water velocities, 

 three species, and four test periods. 



Fish-guiding efficiency tended to decrease with in- 

 creasing water velocity. The guiding efficiencies of the 



ABSTRACT 



electrical systenr at water velocities of 0.2, 0.5, and 0.8 

 (m.p.s.) meter per second were, respectively, 84.2, 

 54.2, and 50.2 percent for chinook salmon; 82.4, 47.8, 

 and 42.8 percent for coho salmon ; and 69.9, 40.2, and 44.8 

 percent for rainbow or steelhead trout. The guiding 

 efficiency achieved was, thus, highest with chinook 

 salmon, intermediate with coho salmon, and generally 

 lowest with rainbow or steelhead trout. 



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 m.p.s. but does not appear practical for use in most 

 rivers and streams. 



One of the major problems facing fishery agen- 

 cies in the Pacific Northwest is that of providing 

 an efficient and economically feasible method of 

 guiding jvivenile salmon and trout past areas po- 

 tentially dangerous to fish. The need is particularly 

 acute in river systems affected by high dams and 

 large, deep storage reservoirs. Recent studies 

 (Durkin, Park, and Ealeigh, 1970) indicate that 

 under certain conditions many juvenile migrants 

 fail to pass through large reservoirs, implying that 

 if natural rims are to be perpetuated, downstream 

 migrants must be guided and collected at the head 

 of a reservoir or in its tributaries. 



Various methods of guiding fish, including the 

 use of electricity (Holmes, 1948; Andrew, Kersey, 

 and Johnson, 1955), louvers (Bates and Vinson- 

 haler, 1957), and of lights and air bubbles (Brett 

 and Alderdice, 1958) have been tested with vary- 

 ing degrees of success. Mason and Duncan ^ de- 

 scribed experiments using the electrical guiding 



^ Mason, James E., and Rea E. Duncan. Development and ap- 

 praisal of methods of diverting flngerllng salmon with electricity 

 at Lake Tapps. Bur. Commer. Fish., Biol. Lab., Seattle, Wash. 

 Manuscript. 



Published June 1970. 



FISHERY BULLETIN: VOL. 68, NO. 2 



principle in which they successfully diverted about 

 90 percent of the juvenile migrants. Their experi- 

 ments, however, were in water velocities of less 

 than 0.3 m.p.s. IBecause the physical conditions at 

 the upstream end of large resei-voirs may vary con- 

 siderably, a guiding system for the collection of 

 juvenile salmon must operate efficiently under a 

 variety of flow conditions. 



The purpose of the present study was to deter- 

 mine the effect of three water velocities — 0.2, 0.5, 

 and 0.8 m.p.s. — on the fish-guiding efficiency of an 

 electrical guiding system operating under field 

 conditions. 



EXPERIMENTAL SITE 



Requirements of the experimental site were : am- 

 ple flows that could be controlled, readily available 

 electric power, sufficient downstream migrants to 

 carry out the tests, and a convenient system for 

 assessing the total outmigration. A section of the 

 Chandler Canal (fig. 1) , a diversion of the Yakima 

 River near Prosser, Wash., met these requirements. 



The Chandler Canal is about 2.4 m. deep, 19.8 m. 



307 



