Negative correlations between larval and juvenile growth rates in winter flounder: implications of compensatory growth for variation in size-at-age

We address the hypothesis that fish that grow rapidly as larvae also grow rapidly as juveniles. Winter flounder Pleuronectes americanus were reared from hatching through the larval period and up to 2 mo into the juvenile period. Successive cohorts of fish which metamorphosed on the same day were pooled and measured at weekly intervals during the early juvenile period. Growth rates of larvae and juveniles were inversely related. This resulted in compensation in size-at-age by juveniles that grew relatively slowly as larvae. Although the complete analysis of juvenile growth rates was confined to Weeks 1 to 4 following metamorphosis, an analysis of early metamorphosed cohorts for which 3 additional weeks of measurements were available revealed that juvenile growth rates exhibited during Weeks 1 to 4 were maintained during Weeks 5 to 7. Among these early metamorphosed cohorts there was evidence that size-at-age converged during Weeks 1 to 7 of the juvenile period. Our results suggest that size advantages gained during the larval period can be lost in the early juvenile period. This is important because size- and growth-dependent processes are known to directly affect survival and reproduction. If growth compensation is general, future studies which examine the consequences of size-dependent phenomena during the larval and juvenile periods of fishes will need to integrate the dynamics of growth in both periods rather than considering them in isolation.