A spatially explicit study of prey-predator interactions in larval fish: Assessing the influence of food and predator abundance on larval growth and survival

Abstract

We apply a coupled biophysical model to reconstruct the environmental history of larval radiated shanny in Conception Bay, Newfoundland. Data on the larvae, their prey and predators were collected during a 2-week period. Our goal was to determine whether environmentally explicit information could be used to infer the characteristics of individual larvae that are most likely to survive. Backward drift reconstruction was used to assess the influence of variations in the feeding environment on changes in the growth rates of individual larvae. Forward drift projections were used to assess the impact of predators on mortality rates as well as the cumulative density distribution of growth rates in the population of larvae in different areas of the bay. There was relatively little influence of current feeding conditions on increment widths. Patterns of selective mortality indicate that fast-growing individuals suffered higher mortality rates, suggesting they were growing into a predator's prey field. However, the mortality rates appeared to increase with decreasing predator abundance, based on the drift reconstructions. The relationship of growth and mortality with environmental conditions suggests that short-term, small-scale variations in environmental history may be difficult to describe accurately in this relatively small system (∼1000 km2).