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 mechano-sensory 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 (50 08 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 (28 01 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 Key words: foraging models; lateral line; predator-prey; reactive distance; vision