Successful Recruitment of Lake Trout to Adult Stage in Southern Lake Michigan

Lake Michigan Lake Trout populations collapsed in the 1950s and a variety of stocking strategies have been implemented to facilitate reestablishment.  All Lake Trout stocked in Lake Michigan have been marked with fin clips or adipose fin clip and coded-wire tag throughout the stocking history, allowing for differentiation between stocked (marked) and wild (unmarked) fish captured in assessment surveys. The presence of unmarked fish in standardized spring lake wide surveys has traditionally been low (6.5% in 2013) with recent increases in the southern basin of Lake Michigan. More notably, fall spawner surveys at two reefs in the Illinois waters have resulted in ~50% of total catch from 2012-2014 being unmarked. Otoliths were collected in the 2014 fall survey from both unmarked Lake Trout with total length ranging from 550-825 mm (n=202) and known age fish (coded-wire tagged) (n=52, total length range: 320-910 mm). Otoliths were embedded in epoxy and thin sectioned for age determination and digital image collection. The result of multiple age classes in wild fish is the first evidence of successful recruitment of Lake Trout to adult stage in Lake Michigan.