Electrical Installation for Control of the 

 Northern Squawfish 



By 



GALEN H. MAXFIELD, GERALD E. MONAN, 



Fishery Biologists 



and HOLBROOK L. GARRETt/ 



Electrical Engineer 



Bureau of Commercial Fisheries Biological Laboratory 

 Seattle, Washington 98102 



ABSTRACT 



Electricity was used experimentally to divert and trap squawfish during their 

 spawning migrationin 1958 at Cascade Reservoir, Idaho. Electrical fields, created by 

 sequentially energizing a V-shaped array of vertically suspended round electrodes 

 with square- wave, d,c, pulses, were evaluated as a means of diverting squawfish into 

 traps. 



Three test conditions of varied pulse frequency, pulse duration, and voltage were 

 tested. Two sets had a pulse frequency of 10 pulses per second (2 per field per sec- 

 ond when five fields were pulsed in sequence), a pulse duration of 50 msec, and volt- 

 ages of 140 and 180 v.; one sethad a pulse frequency of 15 pulses per second (3 per 

 field), a pulse duration of 25 msec, anda voltage of 180 v. One set (pulse frequency, 

 10 pulses per second; pulse duration, 50 msec; and voltage, 180 v.) was repeated. 



The electrical fields of the electrode array were effective in diverting squaw- 

 fish into traps. The test condition with pulse frequency of 15 pulses per second, 

 pulse duration of 25 msec, and voltage of 180 v. was less effective than the other 

 test conditions. 



INTRODUCTION 



The northern squawfish, Ptychocheilus ore- 

 gonensis (Richardson), a predator on young 

 salmon and trout in the major river systems 

 of the Pacific Northwest (Lindsey, 1956), is 

 also a serious competitor of the desirable 

 food and game fishes in many of the lakes 

 and tributary streams of these systems. For 

 example, in northern Idaho, squawfish-- 

 together with other native cyprinids, the pea- 

 mouth Mylocheilus caurinus (Richardson), and 

 longnose dace Rhinichthys cataractae (Valen- 

 ciennes)--and suckers (Catostomidae) have 

 become the dominant fishes in waters that 

 formerly produced trout. The principal cause 

 of this increase in rough-fish populations has 

 been the changes in stream environment-- 

 warmer water, reduced bank cover, siltation, 

 and intermittent flow (Jeppson, 1957). 



In 1957, fishery biologists of the State of 

 Idaho Department of Fish and Ganne began to 

 investigate the life histories of the rough 



fishes and to experiment with partial control 

 measures that could be used when fish are 

 concentrated and thus vulnerable to destruc- 

 tion in large numbers. Jeppson (1957) used 

 gill nets to reduce the number of northern 

 squawfish in 32-hectare Hayden Lake. He also 

 learned that squawfish congregated along a 

 1,6-km. stretch of rocky shoal as spawning 

 time approached; dynamite was effective in 

 dispersing or destroying these schools; Fish 

 Tox and rotenone killed fry, small young-of- 

 the-year, and yearling squawfish; and slight 

 reduction of the lake level during the incuba- 

 tion period killed the eggs that had been laid 

 in shallow areas and subsequently exposed to 

 air when the water level dropped. 



Following Jeppson's work, Richards^ began 

 to study the spawning habits of squawfish at 



■""Now employed as Engineer, U.S. Post Office Dep.,415 

 First Ave. N., Seattle, Wash. 98109 



Trade names referred to in this publication do not 

 imply endorsement of commercial products by the Bureau 

 of Commercial Fisheries. 



■^ Richards, Monte. 1958. Experimental rough-fish con- 

 trol. Idaho Dep. Fish Game [Boise], Annu. Progr. Rep. 

 Fed. Aid Fish Restoration Proj. F 22-R-3, 17 pp. [Proc- 

 essed.] 



