Lake trout supported an important commercial and sport fishery in the Great Lakes until sea lamprey, overfishing, and pollution decimated naturally reproducing populations. By the 1950s, the combination of these factors resulted in the extirpation of lake trout from Lake Michigan. For several decades, management agencies have been working to re-establish self-sustaining, naturally reproducing lake trout populations in Lake Michigan through sea lamprey control programs and hatchery stocking. Recent increases in the proportion of unmarked lake trout adults in fall spawning surveys has revealed the possibility that adults are successfully spawning on deep-water reefs in southern Lake Michigan and that steps are being made toward rehabilitation of lake trout in Lake Michigan. In particular, the proportion of wild to stocked lake trout captured at spawning sites in Illinois has approached 50% in recent years, suggesting that significant natural recruitment is occurring in southern Lake Michigan.
Illinois Natural History Survey • Prairie Research Institute
