Application of Empirical Size-Dependent Models of Larval Fish Vital Rates to the Study of Production: Accuracy and Association with Adult Stock Dynamics in a Comparison among Species

Abstract

A simple model of the size-dependent change in biomass of a cohort of fish larvae based on empirically derived relationships for growth and mortality is presented. Model predictions are compared with data for seven species of larval fish sampled on the Grand Banks of Newfoundland in 1980–81 to determine (1) whether the slope of the size-dependent larval biomass curve is significantly different from the general empirical model, and (2) whether the slope and intercept of the biomass curve are reflective of relative year-class strength and stock abundance, respectively. The slope of the size-dependent larval biomass curve is not significantly different from that predicted by the model in six of seven cases. The slope of the larval biomass curve is not significantly correlated with standardized year-class strength. The height of the curve (i.e. intercept) is only weakly associated with adult stock biomass. I conclude from this set of observations that estimates of larval fish vital rates may not be measured with sufficient accuracy to permit detection of a significant association between deviations from the general empirical model and the factors that may influence survivorship during the larval phase in a comparison across species.