Experimental Assessment of Age‐0 Largemouth Bass and Juvenile Bluegill Competition in a Small Impoundment in Virginia

Abstract

AbstractPrevious research has found that early ontogenetic stages of largemouth bass Micropterus salmoides and bluegills Lepomis macrochirus may compete for food resources in small impoundments in northern‐latitudes. We experimentally assessed whether competition also might occur in a southern‐latitude system by stocking fish allopatrically and sympatrically in 1.0‐m3 cages within a small impoundment in Virginia and monitoring fish growth and diets. Although growth was not significantly different between bluegills stocked with and without largemouth bass, largemouth bass grew significantly larger when stocked alone than when stocked with bluegills. Although bluegills maintained similar diets in terms of sizes, numbers, and types of items consumed, largemouth bass stocked alone consumed fewer but larger items than those stocked with bluegills. Further, largemouth bass consumed higher volumetric proportions of Diptera larvae and Odonata nymphs when stocked alone than when stocked with bluegills. Of these two items, only Diptera larvae constituted a large portion of bluegill diets. Competition between largemouth bass and bluegills apparently occurs in both southern‐ and northern‐latitude small impoundments. Competition with bluegills may result in a competitive juvenile bottleneck for largemouth bass in regions where overwinter mortality is size related, which could affect management (i.e., stocking, establishing harvest regulations) of small‐impoundment fisheries.