Comparative Ecology of Juvenile Striped Bass and Juvenile Hybrid Striped Bass in Claytor Lake, Virginia
Jacob M. Rash and John. J. Ney
Abstract.—Comparisons of juvenile ecology between coexisting striped bass Morone saxatilis and hybrid striped bass (white bass M. chrysops × striped bass) that may limit recruitment to age 1 were considered in terms of trophic relationships, physiological indices of health, overwinter survival, and poststocking predation in Claytor Lake, Virginia. Both fishes preferred habitat types characterized by structure-free sand or gravel substrates, but striped bass and hybrid striped bass did not exhibit significant diet overlap during the growing season. At approximately 120 mm total length (TL), juvenile moronids shifted from a diet of zooplankton and invertebrates to a diet primarily comprised of age-0 fishes. However, piscivorous striped bass primarily preyed on age-0 alewives Alosa pseudoharengus while hybrid striped bass consumed age-0 sunfishes Lepomis spp. The delayed stocking date of hybrid striped bass appeared to contribute to the dietary difference. Striped bass achieved mean total lengths of 229 and 173 mm by the end of the 2001 and 2002 growing seasons, respectively. Mean total lengths of hybrid striped bass stocked into the reservoir 3 months later than striped bass reached 133 mm at the end of the 2002 growing season. Overwinter loss of smaller (<150 mm TL) striped bass was observed for the 2001–2002 sampling period. Predation upon stocked fingerlings was not considered significant in limiting survival; only three fingerling moronids were found in the stomach contents of 200 potential predators captured near stocking sites. It does not appear that resource competition with hybrid striped bass during the growing season resulted in overwinter mortality of juvenile striped bass in our study. Delayed hybrid striped bass stocking may lessen the potential for trophic competition between striped bass and hybrid striped bass at early life stages.