This study was conducted to investigate differences in the anti-predator behavior of larval walleyes (Sander vitreus) and saugeyes (walleye × sauger [Sander canadensis]). Larval fish (5–7 and 12–14 days old) were exposed to a simulated predator to determine the number of attacks required to elicit a response and to determine differences in movement rates and orientation (e.g. time spent in the upper water column) between species related to predator attack. Five to seven day old saugeyes exhibited a response to the model predator on the first or second approach, while walleyes required one to seven approaches. In addition, 5–7 day old saugeyes responded to a simulated attack by rapidly swimming; whereas, walleyes showed little response in swimming action. When larvae were 12–14 days old, both walleyes and saugeyes responded to the simulated predator attack on the first or second approach by rapidly swimming. Regardless of age, neither walleyes nor saugeyes showed a response in orientation to predator attack. This study suggests that anti-predator behavior is one possible mechanism for high survival and recruitment of saugeyes relative to walleyes and that older walleyes (i.e. > 12 days old) should be stocked during years when predator densities are high.
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Vol. 107 • No. 1