The food limitation hypothesis for juvenile marine fish

Coastal zones are productive areas that serve as nursery grounds for a large number of marine species. However, the processes involved in survival success during the juvenile phase are not well-known. Some authors suggest that the availability of prey is important to support the production of pre-recruit fish whose fitness is enhanced through optimal feeding conditions. Accordingly, recruitment is limited by the carrying capacity of the nursery habitat. In contrast, other authors state that the carrying capacity of the nursery grounds is not fully exploited, suggesting that there is no effect of food limitation. This study combines an overview of the literature, focused on flatfish that are especially dependent on coastal and estuarine nursery grounds, an extension to other marine fishes and a modelling approach on growth and survival of juvenile fish to explore the controversy of food limitation in their nursery grounds. We demonstrate that the relative lack of growth limitation observed for young marine fishes at the individual scale is related to an observational bias: fish have been affected by size-selective mortality linked to food limitation, but only surviving individuals are observed. As the population is skewed towards the faster-growing juveniles, the growth of survivors remains close to optimal, even when food resources are limited. Food limitation is of major influence in determining the carrying capacity of the nursery habitat. To sustain marine fish populations and related fisheries, management action is needed to protect coastal and estuarine areas and maintain or restore nursery productivity.