Interannual variation in larval abundance and growth in snapper Chrysophrys auratus (Sparidae) is related to prey availability and temperature

Fish have complex life cycles that contribute to interannual variability in recruitment. The growth-mortality hypothesis has received broad acceptance as a driver of recruitment variability, with cohorts comprised of fast-growing large-at-age larvae having high larval survival and subsequent juvenile recruitment. Long-term monitoring in Port Phillip Bay, Australia, suggests that snapper Chrysophrys auratus (Sparidae) experience high variation in juvenile recruitment, which is closely related to variation in larval abundance. Using a 6 yr data set of snapper larval abundance, we assessed whether growth rate-dependent effects on larval survival were a driver of recruitment variation. Mean daily growth rates, estimated from otolith daily rings, were positively correlated with larval abundances, with higher abundance in 3 of the 6 years characterised by both higher larval growth rates and increased 0-age survival. Daily growth trajectories diverged among higher and lower abundance years early in development. Increased availability of copepod nauplii prey and higher temperatures best explained the interannual variation in larval growth. Fast growth in years of higher larval abundance, and a link between prey production, temperature and fast larval growth, support the importance of the larval stage to recruitment dynamics of marine fish populations.