Demographics of a Commercially Exploited Population of Flathead Catfish in the Wabash River

Flathead catfish, Pylodictus olivarious, are a popular game fish in the Midwestern United States. In the lower 322 km of the Wabash River, flathead catfish are commercially harvested by Illinois and Indiana fishers. Current management regulations are different between the two states. Illinois and Indiana have minimum size limits of 381 and 254 mm respectively. Indiana is in the process of changing their minimum size limit to 381 mm and allowing only one fish over 889 mm to be harvested. Our project will assess the current status of flathead catfish in the Wabash River to inform potential management options for the state of Illinois. We sampled flathead catfish using AC and DC electrofishing during the summer of 2010. To estimate age, we removed pectoral spines from all fish greater than 200 mm. During summer 2010, we conducted 10 hours of AC electrofishing and about 3 hours of DC electrofishing.  Catch per unit effort (CPUE) was higher for DC electrofishing (41.3 fish/hr) compared to AC electrofishing (1.6 fish/hr); however, AC electrofishing sampled larger fish (AC: mean=350.5 mm, DC: mean= 267.4 mm). We aged 68 flathead catfish. Mean age and length of the flathead catfish was 2.9 years and 363.49 mm.  DC electrofishing seems to be a more effective way to sample flathead catfish than AC electrofishing. To represent the size structure of the population more accurately, we will increase our sampling effort to include trotlines, hoopnets, and gill nets in the summer of 2011.