Progress of lake trout restoration in the Great Lakes, 1970's to present. Lake Superior - Lake trout are reproducing throughout the lake and in most Michigan, Wisconsin, and Ontario waters. The rate of reproduction is adequate to sustain the populations without additional stocking. Lake Michigan - Spawning of stocked lake trout and subsequent production of young have been evident since the early 1970's. However, survival of young fish to adults has not been documented.
Offshore reefs appear to be the most promising areas for establishing reproducing stocks.
Lake Huron - Stocked lake trout began reproduction on several nearshore reefs in 1981, and a small number of adults were evident in the annual assessments and creel catches. Intensive stocking of multiple strains on midlake reefs has resulted in the production of young lake trout each year since 1993. Lake Erie - Lake trout stocking began in 1978 and abundance has been improving annually since 1992. Reproduction has not been detected, but lake trout are surviving to sexual maturity and offspring of stocked lake trout have been raised successfully in a hatchery. Although more than 140 non-native species have entered the Great Lakes, the sea lamprey is considered the most harmful.