Effects of DC Electrofishing Pulse Frequency on Collection of Catfish in a Large Midwestern River, USA

Channel Catfish (Ictalurus punctatus), Blue Catfish (I. furcatus), and Flathead Catfish (Pylodictis olivaris) support popular sport and commercial fisheries in the Midwestern United States. In the lower 322 km of the Wabash River, all three are commercially and recreationally harvested by Illinois and Indiana fishers. Our study assessed the sampling efficiency of different pulse frequency settings for boat mounted DC electrofishing in the Wabash River. Fish were sampled with 60 Hz, 30 Hz and 15 Hz pulsed-DC electrofishing during 2010-2013. The greatest abundance and larger Channel Catfish were collected with 60 Hz. Flathead Catfish size was optimal with 60 Hz as well, while lower frequencies sampled more fish. Although our Blue Catfish sample size was small, there is evidence of an effect of pulse frequency on size and number of fish collected; 15 Hz collecting the largest fish and 30 Hz sampled greater numbers than 60 Hz. Our results have very important implications for management because of the inconsistent collection of all three species with a given pulse frequency. If proper regulation assessments are needed for Catfish, the consideration of pulse frequency setting will be very important in determining accurate demographics.