Electrofishing Catchability of Juvenile Muskellunge in Northern Wisconsin Lakes

Inherent assumption of electrofishing surveys that estimate catch per effort (CPE) is that changes in CPE reflect changes in actual abundance. However, capture rates of age-0 muskellunge tend to be low, making it difficult to determine if electrofishing catch is a meaningful predictor of actual abundance. The goal of our study was to determine the effectiveness of electrofishing for capturing age­0 muskellunge by determining locations of stocked fish released into two lakes in northern Wisconsin. Radio transmitters were inserted in to 40 fish per lake and tracked weekly for one month after release. Lakes were also sampled weekly using standard Wisconsin Department of Natural Resources electrofishing methods. Comparing known locations of radio-tagged fish to the area sampled by the electrofishing boat revealed that most of the sampling effort was expended outside the area where fish were located.  The majority of fish remained in the vicinity of the release location moving a max average distance of 0.4 – 0.7 km from the release location within one month of stocking. From this information, biologists can improve sampling protocols to evaluate muskellunge stocking success by stratifying sampling effort so that more time is spent sampling where the fish are located.