Biotic influences on habitat selection by young-of-year walleye (Stizostedion vitreum) in the demersal stage

The influence of prey availability and predation risk on the distribution o f young-of-year (YOY) walleye (Stizostedion vitreum) was investigated by co mparing species associations with the relative abundance of YOY walleye acr oss nine habitat types using an underwater visual assessment technique. Dur ing the early demersal period (mid-June to mid-July), YOY walleye were foun d primarily in areas of high macrophyte cover at 2-5 m depth. YOY walleye a bundance was positively correlated with the abundance of prey fishes at thi s time. YOY walleye shifted to low-cover, shallow areas during the late dem ersal period (mid-July to late August), and the significant prey associatio ns disappeared. Although the selected habitats are considered to have low p redation risk, the distribution of YOY walleye was not related to our index of predator abundance in either time period. YOY walleye were not observed in three of the nine habitat types, suggesting that active habitat selecti on was occurring. High macrophyte cover and prey availability appear to be the major factors influencing habitat selection during the early demersal p eriod. Although our results do not demonstrate the functional significance of the shift of YOY walleye into shallow water, we hypothesize that these h abitats are selected as refugia from particular predators such as adult wal leye.