234 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



ference, however, was not significant at the 

 5-percent level. 



5. The difference between wiring patterns did 

 not cause a significant difference in mortahty. 



6. A significant difference in mortahty between 

 the test fish and the control fish resulted only 

 when two or more of the deleterious variables 

 (square-wave form, low water resistivity, and high 

 frequency) were combined in the tests. 



Delayed effect 



1. The differences in mortality that could be 

 attributed to the differences between the test vari- 

 ations were not significant after the 30-day holding 

 period. 



2. There was no significant difference in mor- 

 tality between the test fish and the control fish 

 after the 30-day holding period. 



In view of these conclusions, it seems logical to 

 infer that, if the electrical shock is going to cause 

 mortalities, most of these mortahties will occur 

 within the first 24 hom's after exposure. 



SUMMARY 



Electricity has been used with some success as 

 a method of diverting fish. However, since its 

 use invariably raises the question of mortality, 

 this experiment was conducted to determine the 

 effect of certain electrical parameters and water 

 resistivities on the mortahty of fingerling silver 

 salmon. 



A Latin square experimental design was used in 

 the investigation with water resistivity, wiring 

 pattern, pulse shape, voltage, and frequency as 

 variables. 



In groups of approximately 100, the fish were 

 subjected to preset electrical and water conditions 

 and then transferred to an outdoor tanlc where 

 they were held 30 days for observation. Four 

 control groups were also tested for continuous 

 comparison of their mortahty with that of the 

 tested fish. 



Statistical analysis of the data to determine the 

 immediate (first day) effect of the conditions tested 

 revealed that (1) square-wave pulses resulted in a 

 significantly higher mortahty than half sine-wave 

 pulses; (2) high frequency (30 p.p.s.) caused a 

 higher mortality than low frequency (15 p.p.s.); 

 (3) low levels of water resistivity (1,000 and 5,000 

 ohm cm.) resulted in a higher percentage mor- 



tahty than high levels (10,000 and 15,000 ohm 

 cm.); (4) although the difference was nonsignifi- 

 cant, high voltage (250 v.) resulted in a higher per- 

 centage mortality than low voltage (165 v.); (5) 

 there was no significant difference in mortality 

 that could be attributed to the difference between 

 the two wiring patterns. 



A chi-square comparison of the test fish with the 

 control fish revealed that a significant difference 

 in mortality existed only when two or more of the 

 three variables which proved to be deleterious 

 (low water resistivity, square-wave pulses, and 

 high frequency) were combined in the tests. 



Effect of the electric shock diminished after the 

 first day; the statistical analysis to determine the 

 delayed effect (second to thirtieth day) revealed 

 that (1) there were no significant differences in 

 mortality that could be attributed to differences' 

 between tlie test variations, and (2) difference in 

 mortality between the test fish and control fish 

 was nonsignificant. 



REFERENCES 



Brett, J. R., and D. F. Alderdice. 



1958. Research on guiding young salmon at two 



British Columbia field station.?. Fisheries Research 



Board of Canada, Bulletin 117, 75 p., 34 figures, 24 



tables. 



Collins, Gerald B., Charles D. Volz, and Parker S. 



Trefethen. 



1954. Mortality of salmon fingerlings exposed to 

 pulsating direct current. U.S. Fish and Wildlife 

 Service, Fishery Bulletin 92, vol. 56, p. 61-81. 



Newman, H. William. 



1959a. A laboratory for fish behavior studies. U.S. 

 Fish and Wildlife Service, Special Scientific Report — 

 Fisheries No. 271, 8 p. 

 1959b. Effect of field polarity in guiding salmon fin- 

 gerlings by electricity. U.S. Fish and Wildlife 

 Service, Special Scientific Report — Fisheries No. 

 319, 15 p. 

 Raymond, Howard L. 



1956. Effect of pulse frequency and duration in 

 guiding salmon fingerlings by electricity. U.S. Fish 

 and Wildlife Service, Research Report 43, 19 p. 

 ScHULTZ, Leonard P. 



1948. Keys to the fishes of Washington, Oregon and 

 closely adjoining regions. 3d printing. Univer- 

 sity of Washington Publication in Biology, vol. 2, 

 no. 4, p. 103-228. 

 Trefethen, Parker S. 



1955. Exploratory experiments in guiding salmon 

 fingerlings by a narrow d.c. electric field. U.S. 

 Fish and Wildlife Service, Special Scientific Report — 

 Fisheries No. 158, 42 p. 



U.S. GOVERNMENT PRINTING OFFICE; 1962 O— 632604 



