Movement and Spatial Distribution of Juvenile Lake Sturgeon in Muskegon Lake, Michigan

Efforts to restore remnant populations of lake sturgeon, Acipenser fulvescens, are hindered by the lack of information on juvenile habitat requirements. We examined the movements and spatial distribution of juvenile lake sturgeon in Muskegon Lake, Michigan, a drowned river mouth lake that links the Muskegon River to Lake Michigan. Juveniles were captured in gill nets, surgically implanted with ultrasonic transmitters, and tracked during August-November in 2008 and 2009 and from September 2010 to November 2011. Weekly vertical profiles of dissolved oxygen concentration and temperature were measured at two locations frequented by juvenile lake sturgeon (September 2010-November 2011). In the summer, juvenile lake sturgeon were observed near (≤ 1.5 km) the mouth of the Muskegon River in Muskegon Lake, then moved to deeper waters at fall turnover (i.e., loss of thermal and dissolved oxygen stratification). Additionally, multiple cohorts of juvenile lake sturgeon were caught in Muskegon Lake throughout the study. Our results suggest that Muskegon Lake serves as an important nursery habitat for juvenile lake sturgeon that hatched in the Muskegon River before they enter Lake Michigan and that there are seasonal shifts in the spatial distribution of juveniles in Muskegon Lake.