Travis O. Brenden and Brian R. Murphy^, Department of Fisheries and Wildlife Sciences, 106 Cheatham Hall, Virginia Tech, Blacksburg, Virginia 24061-0321; Voice 540-231-3329; FAX 540-231-7580;
E-Mail tbrenden@vt.edu, murphybr@vt.edu

Because piscivores during early ontogenetic stages often have diets similar to their prey, mixed competition/predation interactions may be prevalent in fish communities. We tested whether a mixed competition/predation interaction could occur between largemouth bass and bluegill by measuring their diet similarity in a 3.1-ha impoundment in central Virginia during summer and fall, 1997. We collected age-0 largemouth bass and juvenile bluegill by shoreline seining and electrofishing, and analyzed their stomach contents. Diet similarity was quantified with Schoener’s niche overlap index and a bootstrapping technique. Diets did not significantly overlap (â=0.54; approximate p-value>0.10). However, most items consumed by largemouth bass also were eaten by bluegill. At the time this study was conducted, the fishery consisted of moderate densities of small largemouth bass (CPUE=58.11/hour; PSD = 30 & RSD-P = 9) and large bluegill (CPUE=40.26/hour; PSD = 67 & RSD-P = 13). At higher densities, bluegill may expand their realized niche due to intraspecific competition and depress available food resources, possibly affecting largemouth bass growth. Due to their diet similarity, we advise stocking largemouth bass already capable of feeding on the smallest size classes of bluegill available when attempting to restore balance to a stunted bluegill impoundment.