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Diets of Juvenile and Sub-adult Size Classes of Three Micropterus spp. in the Flint River, Georgia: Potential for Trophic Competition

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Sammons, Steven M.


Concerns over the recent introduction of Micropterus punctulatus (Spotted Bass) on native M. salmoides (Largemouth Bass) and M. cataractae (Shoal Bass) prompted a one-year investigation into the food habits of these three congeneric species to determine diet overlap and potential for trophic competition in the Flint River, GA. Diet analyses among species were conducted for two size classes of ¿ sh: juvenile (<200 mm total length) and subadult (200–300 mm TL). Because Spotted Bass had become established in the Flint River only a few years prior to this study, few ¿ sh >300 mm were collected; thus, diet overlap was not compared among species for larger ¿ sh. Juvenile and subadult Largemouth Bass diets were dominated by ¿ sh in all seasons, mainly sun¿ shes (e.g., Lepomis auritus, L. macrochirus). In contrast, Shoal Bass diets were generally dominated by insects and cray¿ sh in the juvenile and subadult size classes, respectively. Juvenile Spotted Bass diets were variable and dominated by ¿ sh and insects depending on season. Overall, diets of introduced Spotted Bass appeared to occupy an intermediate position between Shoal Bass and Largemouth Bass. Signi¿ cant diet overlap between Shoal Bass and Spotted Bass occurred in 50% of the samples, but only in 29% of the samples between Spotted Bass and Largemouth Bass and never between the two native Bass species. Thus, concerns about the trophic effects of Spotted Bass on Shoal Bass appear to be legitimate.