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Novel approach for testing the food limitation hypothesis in estuarine and coastal fish nurseries

A. Tableau*, H. Le Bris, E. Saulnier, O. Le Pape, A. Brind’Amour

*Corresponding author:

ABSTRACT: Survival success of early life stages of fish is regulated by density-dependent effects, but the limiting factors explaining these effects are not well identified. In coastal habitats, juveniles of many fish species are observed in high concentration and possibly compete for food resources. This study compares the ratio of food consumption to benthic prey production to test whether food availability is a major factor defining the carrying capacity of fish nurseries. We develop a method to quantify the exploitation efficiency, also called ecotrophic efficiency, of the fish juveniles feeding on benthic prey. It is a ratio of the food consumption over the food production. This method includes many sources of uncertainty and a key parameter of prey accessibility. Applied to the case study of the Bay of Vilaine (North Bay of Biscay), the results suggest food limitation for juvenile fish. The generic nature of the method supports its wide application in various nursery habitats. As food limitation is a density-dependent process having a dampening effect on the recruitment variability, concluding on its occurrence over time and space would improve our comprehension of nursery-dependent fish dynamics.