Effect of Backpack Electroshock on Westslope Cutthroat Trout Injury and Growth 110 and 250 Days Posttreatment

Westslope cutthroat trout Oncorhynchus clarki lewisi that were reared under captive conditions were exposed to 0.75–1.5 V/cm of continuous, 50-Hz pulsed, or variable pulsed (CPS) direct current (DC) for 5 s to determine whether their growth after 110 and 250 d was affected. Individually marked fish served as experimental units. Only one fish, which was shocked in the CPS treatment, died following treatment. After 110 d, fish that underwent CPS and 50-Hz pulsed-DC electroshock treatments had gained significantly (P < 0.05) less weight than control fish, but weight gains by fish exposed to continuous DC were not significantly different from those of control fish. After 250 d, fish exposed to any of the three treatments had gained significantly (P < 0.05) less weight than control fish. At the conclusion of the experiment (250 d), four observers examined the fish to assess whether they had suffered spinal injury. Significantly (P < 0.05) more fish that had undergone electrofishing treatments exhibite...