Evaluation of recreational hand-crank electrofishing on introduced catfish species in southeastern North Carolina.
Introductions of nonnative catfishes have led to population declines in native aquatic species. Populations of nonnative catfishes have been established in the Cape Fear, Black, Lumber, and Waccamaw rivers in southeastern North Carolina for 20-50 years. In response to native fish declines, the removal of nonnative catfishes has been encouraged in specific reaches of these rivers by utilizing recreational hand-crank electrofishing (HCE). This unique recreational gear type has been legal since 1985, but the impact of HCE on catfish species in all rivers where it occurs has not been evaluated. Therefore, our objective was to describe and compare population characteristics of nonnative Flathead Catfish Pylodictis olivaris, Blue Catfish Ictalurus furcatus, and Channel Catfish I. punctatus in river reaches where HCE is allowed (HCE reaches) to those in reaches where HCE is prohibited (non-HCE reaches). Low- and high-frequency electrofishing was utilized to assess population dynamics, age structure, size structure, biomass, and condition of catfish species in HCE and non-HCE reaches of the Cape Fear, Black, Lumber, and Waccamaw rivers during 2015 and 2016. Populations of the three nonnative catfishes collected in HCE reaches exhibited more characteristics indicative of exploitation compared to those in non-HCE reaches. Recreational HCE at current harvest levels appears to have limited impacts on nonnative catfishes, while other factors (e.g., habitat) likely play a larger role in structuring these populations.