Pylodictis olivaris (Flathead Catfish) are large piscivores native to western Gulf of Mexico drainages that have been widely introduced into Atlantic Slope drainages with largely unknown consequences for native lotic faunas. From 2009–2011, we assessed the diet, demography, growth, and spatial distribution of Flathead Catfish in the lower Tar River in east-central North Carolina. We documented current presence of Flathead Catfish using electrofishing at 27 sites in the Tar River and its tributaries Fishing and Sandy creeks and examined diet and growth rates in the lower Tar River population. Stomach contents revealed that Tar River Flathead Catfish are primarily piscivorous but also consumed a diverse range of prey items. Canonical correspondence analysis found that Flathead Catfish ≥500 mm TL appeared to consume centrarchids at greater rates than smaller Flathead Catfish, suggesting a shift to larger prey in larger, older fish. Body-condition analysis found that condition did not change with body size, suggesting that the lower Tar River population has likely not yet over-exploited its resource base. Upstream distribution of Flathead Catfish in the upper Tar River and Fishing Creek, two important refuges for numerous imperiled lotic taxa in this fragmented drainage, appears restricted by two small dams. Our data suggest a need for continued monitoring for natural and human-mediated Flathead Catfish range expansions into sensitive reaches as well as empirical study of possible species-, assemblage-, and ecosystem-level effects of this apex predator on imperiled freshwater biota in the Tar River. Moreover, tabling the removal of some small dams in the Tar Drainage may be a prudent action capable of protecting sensitive taxa, at least in the short-term.
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Vol. 14 • No. 1