Zoology Faculty Work


Effects of Repeated Electroshocking on Condition, Growth, and Movement of Selected Warmwater Stream Fishes

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North American Journal of Fisheries Management

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The purpose of this study was to determine the effect of repeated monthly use of pulsed‐DC electrofishing on condition factor (K), instantaneous growth rate (G), and movement of stream‐dwelling creek chub Semotilus atromaculatus, white suckers Catostomus commersonii, and green sunfish Lepomis cyanellus. Fish that were captured five or more times by approximately monthly electrofishing were compared with control groups. Analysis of variance (ANOVA) models indicated that repeated electroshocking had such a minute impact (≤0.2% reduction in error sum of squares) on K that this effect was unlikely to be biologically meaningful, especially given that it was positive for white suckers. Similar models for G showed small but statistically significant decreases in white sucker and creek chub G‐values from repeated monthly electroshocking; there was no effect for green sunfish. An additional model analyzing the impact of repeated electroshocking of white suckers at bimonthly intervals showed no significant effect on G. For all three species, the relative frequency of remaining stationary or exhibiting net movement upstream or downstream was similar between repeatedly electroshocked fish and control fish, as were the net distances moved in either direction. Thus, monthly applications of electrofishing had minimal negative effects on K for only two of the three species; slightly larger negative effects on G for only two species; and no measurable effects on movement of any species. In contrast to the effect of monthly electroshocking, bimonthly exposures did not negatively affect G for white suckers. Overall, the results suggest that pulsed‐DC electrofishing (60 Hz; 36% duty cycle) is a safe methodological tool for studying these species, provided it is not used too frequently.



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