Collaborative Research: Open-water Planktivores and Turbidity: Their Influence on Size-structured Interactions among Centrarchid Fishes

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Most lakes and reservoirs of the southeastern and central United States differ from upper-midwestern lakes by having very turbid water and the presence of open-water fish species which feed predominantly on zooplankton (e.g., gizzard and threadfin shad). These two factors have profound effects on the production of invertebrates and fishes in lakes. This study will examine how the presence of shad affects fish species interactions, as well as studying the impact of shad on other aspects of the lake system (e.g., algae and zooplankton). It seeks to extend the substantial understanding gained from studies of northern fish communities to a geographically broader portion of the country. Because species interactions in fishes are often complex due to changes in their diet and habitat use as they grow, (e.g., many large predatory fish begin their lives feeding on small zooplankton), the impact of shad and turbidity can only be understood by considering how each factor influences all points in a fish's life history. The project will utilize a series of laboratory, pond, and whole-lake experiments designed to examine the effect of shad on the larvae, juveniles and adults of three important sport fishes; bluegill, largemouth bass, and white crappie. This work capitalizes on a unique opportunity to study fish, zooplankton and phytoplankton in two Ohio reservoirs before and after the whole-lake introduction of threadfin shad. The study will provide much needed insight into the effects of introduced planktivores on the resident fish fauna and their potential role in lake management. Ohio Department of Natural Resources is funding additional research on the study reservoirs which will add generality and depth to the total information base being generated.