Light intensity, prey detection and foraging mechanisms of age 0 year yellow perch

The ability of age-0 year yellow perch Perca flavescans to detect prey using visual and mechanosensory input was examined during laboratory feeding trials at varying light intensities. Perch were highly effective predators and captured Daphnia pulicaria with 94% overall foraging success at light levels ranging from 0 to 3400 lx. Maximum average reaction distances (5 0 0 8 cm, mean S.E.) occurred in front of the fish at 3000 lx and significantly decreased as light intensities fell to <2 lx, with minimum reaction distances (2 8 0 1 cm) observed in the dark. Following chemical ablation of the lateral line, yellow perch showed a significant reduction in reaction distance when compared to the untreated fish at 3000 lx, suggesting that the lateral line may augment visual prey detection at high light levels. A model was created to predict reaction distances for fish feeding with multiple sensory systems that can be applied to a variety of photic environments. This study provides a better understanding of the contribution of vision and the lateral line to prey detection, and relates the reaction distance of age-0 year yellow perch to light intensities similar to those experienced in nature. # 2004 The Fisheries Society of the British Isles