Survival of prey growing through gape-limited predators

Abstract

Juvenile to adult survival of fish is modeled by the rate at which prey progressively escape the size distribution of gape-limited predators through growth. The model characterizes adult survival as a function of the mean and standard deviation of the predator population gape sizes, the ratio of mortality and growth rates and a compensatory growth factor. The model fits the survival of adult returns of Chinook salmon and reveals that a 25% increase in either the initial size at ocean entrance or the growth to mortality rate over the first few months of ocean residence can increase adult survival by a factor of 2 to 3. Additionally, the model proposes a rigorous mechanism through which the size distribution of predators determines the effects of juvenile growth on adult survival. Finally, possible contributions of the model framework to fisheries management and predator-prey theory are noted.