VULNERABILITY OF STRIPED BASS MORONE-SAXATILIS WALDBAUM EGGS AND LARVAE TO PREDATION BY JUVENILE WHITE PERCH MORONE-AMERICANA GMELIN

Striped bass Morone saxatilis Waldbaum early life stages and juvenile congeneric white perch M. americana Gmelin co-occur in Chesapeake Bay tributaries. Vulnerabilities of striped bass eggs and laboratory-reared larvae to predation by juvenile (58-65 mm total length) white perch were determined. Predation experiments of 15-min duration were carried out in 76-1 tanks with individual predators. Vulnerability of striped bass larvae was directly related to light level in the range 0-1000 lux, but turbidity level (0-15 NTU) had no effect on vulnerability. Eggs and larvae that were progeny of large or small female striped bass, and which differed in size-at-age, were found to be equally vulnerable to white perch predation. Predation rate on eggs was relatively low (1.7.15 min-1), increased on yolk-sac larvae (7.3.15 min-1) and was highest (13.1.15 min-1) on 12-day posthatch larvae, after which it declined. Larvae of 7.0-7.9 mm standard length and 0.25-0.49 mg dry wt were most vulnerable. Predation by white perch on striped bass eggs and larvae potentially is a significant cause of mortality in Chesapeake Bay tributaries, although additional laboratory and field experiments are needed to quantify its impact.