Movement and habitat use of juvenile lake sturgeon (Acipenser fulvescens) in a Lake Michigan tributary

Knowledge on the ecology of the juvenile lake sturgeon (Acipenser fulvescens) is critical for successful management and restoration of this imperiled species. The Muskegon River located in west-central Michigan supports a remnant population of lake sturgeon. During fall 2008 and 2009, we captured and monitored the movements of juvenile lake sturgeon in Muskegon Lake, which connects the Muskegon River to Lake Michigan. In total, 14 juvenile lake sturgeon (age 0+ to 7+ years) were captured; the movements of 10 were monitored during August-November of both years. Fish captured during August-September inhabited depths between 1.2 and 11.0 m and, with the exception of one fish, remained within 1.8 km of where the Muskegon River enters Muskegon Lake. As water temperature declined, fish gradually migrated to deeper waters, using depths of >21 m at times. Juveniles captured during October-November were located at depths >19 m. Movements of juvenile lake sturgeon over a 24-hour period varied widely among individuals (32-2,203 m). All fish were located over fine substrates (e.g. silt), and none were found in vegetated areas. Our results suggest that juvenile lake sturgeon use Muskegon Lake as a nursery habitat after hatching upstream in the Muskegon River before entering Lake Michigan.