Bighead Carp Effects on the Growth and Abundance of Larval Bluegill

Following their introduction into the Mississippi and Illinois River systems, it has been shown that Asian Carp effectively reduce the abundance of zooplankton within these systems.  There is evidence to suggest that exploitative competition between Asian Carp and native planktivores occurs; however, little is known from controlled manipulative experiments or about their effects on native non-planktivorous fish with larval stages relying on zooplankton. Mesocosms and ponds were used to test the effect of Bighead Carp (Hypophthalmichthys nobilis) on the growth and abundance of larval Bluegill (Lepomis macrochirus).  Golden Shiners (Notemigonus crysoleucas) were also used to differentiate the effects of native versus invasive planktivores.  In the presence of Bighead Carp, larval Bluegill exhibited significantly lower total biomass and condition.  In contrast, larval Bluegill exhibited similar biomass and condition when in the presence of Golden shiners as when alone.  Differences in responses were correlated with differences in zooplankton abundance between treatments over time.  These results demonstrate that Asian Carp, in comparison to a native planktivore, may have negative effects on the larval stage of native fish within the Mississippi and Illinois River systems, with implications for potential range expansions to the Great Lakes.