Evaluation of the flood-pulse concept based on statistical models of growth of selected fishes of the Upper Mississippi River system

The flood-pulse concept (FPC) states that annual inundation is the principa l force responsible for productivity and biotic interactions in river-flood plain systems. Somatic growth is one component of production, and we hypoth esized that, if the FPC applies, growth of fishes that use the moving litto ral zone should differ among years with differing flood pattern, whereas no nlittoral fishes would show no such response. Growth of largemouth bass (Mi cropterus salmoides) and bluegill (Lepomis macrochirus), species that explo it littoral resources, increased during a year having an unusual warm-seaso n flood in the Upper Mississippi River system and was reduced during low-wa ter years. Growth of white bass (Morone chrysops), which do not rely heavil y on the littoral zone, did not differ significantly between the extreme-fl ood and low-water years. Patterns of growth of black crappie (Pomoxis nigro maculatus), which have intermediate dependence on the moving littoral zone, were somewhat ambiguous. These results are consistent with the hypothesis that the FPC applies, at least under certain conditions, to this temperate river system. Our results can also provide an important basis from which to assess some costs and benefits of water level management strategies in lar ge regulated temperate rivers.