Spatial distribution and diet of Lake Michigan juvenile lake trout

Most studies of Lake Michigan lake trout (Salvelinus namaycush) have focused on adults, with scant attention to juveniles ( 170 mm (∼age-2+). Largest catches of wild lake trout 170 mm were collected along southern transects. Mysis diluviana was the dominant prey for juvenile lake trout 250 mm were primarily piscivorous, while 170–250 mm appeared to be a transitional period of switching from Mysis to fish. Species composition of prey fishes consumed by lake trout varied spatially and we found evidence of seasonal and annual diet variation within Grand Traverse Bay. Diporeia, once an important component of juvenile lake trout diet, appears to no longer be consumed by juvenile lake trout in Lake Michigan to any measurable degree. Continued research on the ecology of juvenile lake trout may provide insight into the effects of a changing ecosystem on juvenile lake trout diet and growth, thereby contributing to the effort to rehabilitate the Lake Michigan lake trout population.