Sleeping Giants: The Ecology and Impacts of Domestic Invasive Large Catfish

Large North American ictalurid catfishes (channel catfish, blue catfish, flathead catfish) have been widely introduced in the United States beyond their native ranges.  These domestic invasive species receive less scientific and media attention relative to exotic fish introductions, but their ecological impacts may be equally or more severe.  They have been implicated for the decline of sport fishes, imperiled fishes, and amphibians.  Introduced flathead catfish are of special concern, because they are an aggressive obligate carnivore with great potential to alter native fish assemblages.  Since the 1950s, they have been introduced into Atlantic Slope rivers from Florida to Pennsylvania, established by releases of few individuals.  The flathead catfish has been considered easily collected by electrofishing, of low densities, with sedentary behavior, restricted to freshwater, and feasible to manage in restricted river units, but recent research suggests that electrofishing is an inefficient gear, it occurs in dense populations, individuals migrate throughout a drainage, it tolerates brackish waters, and populations must be managed at the basin scale.  Management of introduced catfish focuses on limiting dispersal among basins, public education, and encouraging harvest.  Additional research is needed to elucidate the effects on native fishes and develop and assess alternative population control measures.