Feeding Habits of Walleye Larvae and Juveniles: Comparative Laboratory and Field Studies

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Abstract
The feeding habits of larval and juvenile walleyes S. vitreum were examined in the field and laboratory. Walleyes are strike feeders and rely on vision to capture food. The mouth, jaws and teeth are strongly developed by the time feeding begins about 5 days after hatching, but the gill rakers do not develop a filtering function until the juveniles are 20-30 mm long. The preferred food of postlarvae was crustacean zooplankton, about 1.2 mm in total length. Rotifers were not consumed at normal pond densities. Size selection of prey was more important than species selection. During the juvenile stage, walleye food preference shifted from zooplankton to larger, faster prey; first to Chaoborus sp. and mayflies, later to Gammarus lacustris and fish. The rate of food consumption by juveniles varied with food preference; it was highest with Chaoborus sp. and fish, lower with Daphnia pulex, and lowest with G. lacustris. The food consumption rate was linearly proportional to food density when D. pulex was fed at densities < 100/l. In highly turbid ponds, there were 3 periods of feeding activity per day, separated by 8 h intervals. The feeding periodicity of smaller walleyes was opposite to that of larger walleyes when both were present together in a pond. Predation on smaller fish (including cannibalism) was 1st observed when walleyes reached a total length of .apprx. 30 mm.
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