If it's There, They'll Find it: Reef Utilization by Lake Trout Populations 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 andcoded-wire tag (CWT); Julian's Reef, a designated Lake Trout stocking area in Illinois waters, has been stocked since 1981. To evaluate success of reestablishment we monitored the spawning population at Julian's Reef with annual (1999-2014) October-November gill net surveys and compared this to the success of a nearby undesignated location, Waukegan Reef. There was no difference in catch per unit effort between the spawning sites (P = 0.18). Unmarked fish have increased exponentially at both locations with~50% of the recent catch having no fin clips. Information from CWTs indicated that a greater proportion of fish sampled on both reefs were stocked outside of southern Lake Michigan (90-680 km away), and these fish were significantly older (P's<0.01) compared to those stocked on Julian's reef. Trends in age, origin, abundance and location offers valuable insight into the populations utilizing designated and undesignated reefs, and should be considered in a lake wide monitoring context by Lake Michigan managers.