PRECISION OF RECRUITMENT PREDICTIONS FROM EARLY LIFE STAGES OF MARINE FISHES

To test the hypothesis that year-class strength in marine fishes is determined in the early-larval stages, and that these stages can be used to predict recruitment, I modeled the recruitment process using a modified form of key-factor analysis. Using data compiled from the fish literature, I found a significant relationship (R2 0.90, p much less than 0.001, n 97) between the mean and interannual variance of stage-specific mortality rates that provided variance estimates for the model. The R2 values for the true correlation between abundances of small larvae and subsequent recruitment for four example species of marine fish were predicted to lie between 0.10 and 0.57, depending on the assumptions of the model. I therefore suggest that recruitment levels are fixed after the early-larval period. However, the precision of sample correlations are too low (10-yr data series) to empirically test whether abundances or mortality rates of early larvae are in reality strongly or poorly correlated with recruitment. After metamorphosis, the strength of the true relationship and the precision of sample correlations increase sufficiently to permit precise forecasting of recruitment. Recruitment is a complex process in which variation in all life stages contributes substantially to the variability in final abundance; therefore, researchers should recognize the importance of the later prerecruit stages and the interactions among all stages.