Evidence of Wild Juvenile Lake Trout Recruitment in Western Lake Michigan

Lake Trout Salvelinus namaycush were extirpated from Lake Michigan by the early 1950s, and as part of an effort to restore naturally reproducing populations, hatchery-reared fish have been stocked since the early 1960s. Stocked fish are marked with a fin clip to differentiate them from wild, lake-produced Lake Trout; marking error for the 20072010 year-classes of Lake Trout stocked by federal hatcheries averaged 3.0%. Egg deposition, emergent fry, and wild juvenile Lake Trout have previously been observed, but no sustained wild recruitment has been measured in assessment surveys or in sport and commercial fishery catches. In 2011 and 2012, we caught juvenile Lake Trout in gill-net and bottom trawl catches that were targeting Bloater Coregonus hoyi in water depths greater than 80m. Unclipped, wild Lake Trout represented 20% of all Lake Trout caught in a southern offshore region of Lake Michigan. In northwestern Lake Michigan wild recruits represented from 10% to 27% of the 20072009 year-classes, and we recovered a small number of wild Lake Trout from the 2010 year-class. This is the first evidence for consecutive year-classes of naturally produced Lake Trout surviving beyond the fry stage in Lake Michigan. Received July 13, 2012; accepted November 26, 2012