to Seattle. The fish stored at Little 

 White Salmon hatchery had been obtained (1) 

 by seining and by hook-and-line fishing in 

 Drano Lake, (2) by hook- aind- line fishing in 

 the Columbia River near the Spring Creek 

 hatchery, and (3) by seining in a drainage 

 ditch at Echo, Oregon. The fish stored at 

 Leavenworth hatchery had been trapped both 

 in the forebay and in the fishway at Rock 

 Island Dam, Washington. The fish stored 

 at Bonneville hatchery had been trapped in 

 the fingerling bypass at Bonneville Dam. 

 These fish were transported to Seattle in 

 100-fish lots, and most lots of the fish 

 were placed in screen traps in lake water 

 near the laboratory. Some lots were held 

 in outdoor hatchery raceways in lake water 

 at the School of Fisheries, University of 

 Washington, Seattle. 



Apparatus and Measurements 



The experimental area (fig. 1) in the 

 laboratory was a portion of a larger insu- 

 lated tank constructed for electrical 

 studies on salmon fingerlings. The con- 



crete floor and construction block walls 

 were equipped with an electrically insulated 

 lining of several coats of Amercoat paint. 

 The inside dimensions of the experimental 

 area were 24 feet 10 inches by 14 feet by 

 16 inches. The depth of water was approxi- 

 mately 11 inches during the period of the 

 study, and the water was not in motion. 



The electrodes used in the array were 

 of 1/2 inch outside diameter ciluminum 

 tubing, 12 inches long. Two holes were 

 drilled at one end of each electrode; a 

 T-shaped copper wire with a copper slim- 

 nosed alligator clip soldered onto the base 

 of the T was inserted into the holes. The 

 electrodes were suspended in the water, to 

 an approximate depth of 10 1/2 inches, from 

 ten rows of parallel copper wires secured 

 to insulators. The wires were strung at 

 right angles across the center of the ex- 

 perimental area. The distance between the 

 rows was 18 inches, and the electrodes were 

 spaced approximately 17 inches apart in 

 each row in a staggered array (figs. 1 and 

 2). 



Figure 2. — Staggered electrode array used in laboratory. 



