Effects of simulated light intensity, habitat complexity and forage type on predator-prey interactions in walleye Sander vitreus

Predator-prey interactions can be influenced by the behaviour of individual species as well as environmental factors. We conducted laboratory experiments to test for the influences of two abiotic factors (light intensity and habitat complexity) on predatorprey interactions between walleye Sander vitreus and two prey species, bluegill Lepomis macrochirus and golden shiner Notemigonus crysoleucas. Three light intensities were simulated (day, twilight and night) in the presence or absence of simulated vegetation. Observations of predator behaviour indicated that walleye increased activity and foraging success with decreasing light levels and had most success capturing dispersed, closer prey. While schooling could not be maintained as light levels diminished, prey decreased predation vulnerability by moving into vegetation or higher in the water column. Throughout all treatments, bluegill were more evasive to capture as the number of strikes was similar on both prey but capture rates were higher for golden shiner. Although light intensity and simulated habitat complexity affected predator and prey behaviour, these factors did not interact to influence foraging success of walleye. To fully understand predator and prey behaviours in fishes, an understanding of species-specific responses to abiotic and biotic factors is necessary.