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Abstract
Electrofishing is widely used to monitor freshwater fishes. Electrofishing sampling appears to be relatively harmless when used appropriately, but biologists have questioned its effects on fishes. Although studies report injury and mortality due to electrofishing, few report effects on reproduction. We assessed the hypothesis that exposure to electroshock alters reproductive processes and output in the Red Shiner Cyprinella lutrensis by determining if pulsed DC has negative effects on interclutch time intervals, clutch sizes, proportion of viable eggs produced by spawning pairs, growth, and recovery time. A total of 125 breeding pairs, with an average of 4.91 (SD, 0.44) spawning events per pair, were used in the study. All dependent variables were tested for the influence of frequency (60 and 120 Hz) and voltage (100 and 400 V) and compared with spawning pairs that were not shocked (a control group). We found that the interclutch time interval was increased, the proportion of viable eggs was reduced, and the recovery time was extended when using the higher-voltage (400 V) compared with the control and lower-voltage (100 V) treatments. The total number of eggs laid by females showed no significant differences between treatments. The higher voltage significantly reduced the weight and SL in males, likely due to injury. To our knowledge, this is the first study to report the influence of electroshock on reproduction in iteroparous fishes. The Red Shiner is not a typical target species in fisheries, so the general applicability of the results to other species requires investigation.
Received August 5, 2013; accepted January 8, 2014
ACKNOWLEDGMENTS
We thank J. Pangle for logistic support throughout the project, and K. Cradock, C. Harthorn, and the Eastern New Mexico University Fish and Wildlife Club who assisted with fish and data collection. We also thank Eastern New Mexico University for financial support from an Internal Research Grant to M.M.F.L., and J. Chacon, T. Fares, R. Howard, and J. Kanmore for laboratory maintenance. Finally, we thank T. Archdeacon, J. Gross, Z. Jones, D. Pollock, and two anonymous reviewers for critical comments on versions of the manuscript, or for discussion.