Is density-dependent growth in young-of-the-year fishes a question of critical weight?

We develop a conceptual argument that density-dependent growth via reductions in prey resources are most likely to occur in the late-larval or juvenile stage in both marine and freshwater fishes. We use results from a suite of individual-based models and literature examples of a variety of marine, estuarine and freshwater species to provide evidence of the effects of age-0 fish on their prey. We conclude that larval-stage survival related to food-limited growth contributes significantly to recruitment variability. However, density-dependent regulation of cohort biomass via feedbacks derived from reductions in prey resources is most likely to occur at a "critical-weight'' during the late-larval or juvenile stage. This occurs when fish densities remain relatively high, and population consumption is highest relative to prey density and replenishment rate. We compare our critical weight concept to Houde's (1997) critical size hypothesis.