Effect of Hull Cleaning on Electrical Resistance and Anodic Fields of Direct‐Current Electrofishing Boats

Abstract

AbstractIn 2011, the Iowa Department of Natural Resources began standardization of its direct‐current electrofishing boats, including development of a standard operating procedures document. After publication of standard methods for sampling freshwater fishes by the American Fisheries Society, the Iowa Department of Natural Resources incorporated these standards into its standard operating procedures. Literature and references about maintaining electrofishing equipment were lacking. One aspect of equipment maintenance is hull cleanliness when the hull is metal and serves as the cathode. The cathode affects system resistance and overall performance of the electrofishing equipment. Four boats were used to measure system resistance and changes in the electrical fields after cleaning the cathodes. Boat electrofishing field intensity was measured pre‐ and postcleaning. Boat cathodes were cleaned 25, 50, and 100% of the length of the hull using a wire wheel attached to an angle grinder. Based on our results, 100% of the cathode should be cleaned when standardized resistance (R100, system resistance when ambient water conductivity is 100 μS/cm) increases 10% above baseline values. Baseline R100 values for the four boats in this study were between 25 and 30 Ω. The R100 value is a quality‐control indicator of electrofisher performance.