224 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 1. — Latin square experimental design 

 (The rows are comprised of water resistivities, the columns of wiring patterns and pulse shapes, and the treatments of voltages and frequencies) 



• Pulse per second. 



As shown in table 1, a total of 16 tests were 

 conducted with the array energized. In addition, 

 four gi'oups of fish were tested with the power off 

 to serve as controls. Each control group was 

 tested in one of the water resistivity conditions 

 used during the power-on tests. Each group, test 

 or control, consisted of appro.ximately 100 silver 

 salmon fingerlings. 



Prior to testing, each group of fish was tattooed 

 with a distinctive mark. The fish were then ex- 

 posed to electric shock in an experimental tank 

 and, after examination for immediate mortalities, 

 they were transferred to an outdoor holding tank 

 where they were held .30 days for observation. 

 The tattoo marks provided a means of identifying 

 each group of fish during the 30-day holding period. 

 Observations were made daily and a record of 

 mortalities was maintained. 



Test flsh 



The test fish were age-group silver salmon 

 {0. kisutch) obtained from the national hatchery 

 at Quilcene, Washington. They were transported 

 to the Bureau of Commercial Fisheries Biological 

 Laboratoiy, Seattle, Wash., in an aerated tank 

 and held in outdoor holding tanks prior to testing. 



The fish ranged in size from 55 to 98 mm., 

 measured from the tip of the snout to the posterior 

 end of the vertebral column (standard length 

 measurement illustrated by Schultz, 1948). The 

 average standard length was 85 mm. 



Laboratory facilities 



The experiment was conducted in the fall of 

 1959 in the main experimental tank of the fish- 

 behavior laboratory described by Newman (1959a). 

 This tank is 20 feet wide, 58 feet 6 inches long, 

 and 5 feet deep. It was divided lengthwise by 

 installing a partition constructed of ?^-inch ply- 

 wood, creating a channel 10 feet 2 inches wide 

 (fig. 1 ) . Installation of this partition produced the 

 desired conditions (depth of water, 1 foot; average 



water velocity, 1 foot/second) without altering any 

 of the existing laboratory facilities. 



The floor and walls of the e.xperimental channel 

 were coated with asphalt and insulating paint to 

 minimize electrical gi'ounding. Horizontal baffles, 

 designed to produce a uniform flow of water, were 

 installed in the headbox (fig. 2). Both ends of the 

 channel were screened with J^-inch hardware cloth 

 to confine the fish to the test area. 



A release box (fig. 2), 4 feet by 2 feet 10 inches 

 by 2 feet with a removable gate, was placed in 

 the channel approximately 8 feet downstream 

 from the headbox. A block-and-tackle assembly 

 enabled us to remove the box from the water after 

 release of the test fish. A second box with the 

 same design and dimensions, but fitted with lead-in 

 nets, was placed at the downstream end of the 

 channel (fig. 3). This second box was used in the 

 recovery of the fingerlings after they had passed 

 through the test area. 



Two troughs, each 66K by 9K by 2>]i inches, 

 were set up in an area adjacent to the experi- 

 mental tank (fig. 4). One trough was placed on a 

 rack 4 inches higher than the other and served as 

 a gravity-flow reservoir for the lower trough and 

 a holding area for the fish prior to tattooing. The 

 lower trough served as a table for the tattoo- 

 ing machine and as a holding area for the test fish 

 after they had been tattooed. Water was supplied 

 to the upper trough at a rate of one-half gallon 

 per minute by means of a submersible pump 

 placed in the headbox of the main experunental 

 tank. A standpipe overflow returned the water 

 from the lower trough through a flexible hose to 

 the experimental tank headbox. This system 

 maintained a constant flow of water through the 

 troughs and a stable water level in the experi- 

 mental tank. 

 Electrical equipment and test conditions 



Array. — The electrode array consisted of a 10- 

 by 5M-foot wooden framework with cross mem- 



