A Gastric Evacuation Model for Young Yellow Perch, Perca flavescens

Abstract

Gastric evacuation times for age 0+ yellow perch (Perca flavescens) (20–69 mm total length) fed continuous meals of zooplankton were measured in the laboratory. The pattern of gastric emptying was described using a segmented regression with two linear sections joined at a fish length of 36.5 mm. It was assumed that evacuation time (hours) is dependent on the amount of food in the stomach; the variables prey size and meal size were the primary determinants of stomach food volume. A gastric evacuation time model was developed; model parameters of evacuation time were quantified as functions of fish size, prey size, and numbers of prey in the stomach. For fish <36.5 mm, all three variables improved the regression model (P < 0.05), while for larger fish, only the number of prey in the stomach and fish length contributed (P < 0.05) to the explained variance in evacuation time. Estimates of evacuation time were applied to a model of prey consumption and it was found that predicted food intake did not differ significantly from direct counts (P > 0.05).