Variation in larval growth can predict the recruitment of a temperate, seagrass-associated fish

Abstract

Understanding the factors leading to inter-annual variation in recruitment of animals with complex life cycles is a key goal for ecology and the sustainable management of animal resources, such as fisheries. We used otolith microstructure to determine larval growth rates of post-larval King George whiting, Sillaginodes punctata, in seagrass beds of Port Phillip Bay, Australia. Inter-annual variation in growth determined early in the pelagic, offshore larval-stage was highly correlated with post-larval abundance (a predictor of fishery recruitment). Sea surface temperature measured near the presumed spawning area off Western Victoria was significantly correlated with larval growth, and was also significantly correlated with post-larval abundance in Port Phillip Bay. Increased water temperature would have had the direct effect of increasing larval growth and therefore contributing to larval survival, but may also have been indicative of enhanced physical transport and/or plankton productivity. Overall, larval growth rate of King George whiting is a very strong predictor of post-larval abundance, which in turn will influence fishery recruitment in 3-5 years' time.