Movement and Habitat of Juvenile Lake Sturgeon (Acipenser fulvescens) in the Sturgeon River/Portage Lake System, Michigan

ABSTRACT

The Portage Lake/Sturgeon River system in Michigan contains one of the last self-sustaining stocks of lake sturgeon (Acipenser fulvescens) in the Great Lakes without barriers to impede natural movement of juveniles. We conducted visual surveys in the Sturgeon River and collected young-of-the-year and juvenile lake sturgeon from 1997 to 2000. Twenty-four fish, 9.8 to 28.8 cm total length (TL), were found predominately over pea gravel 16 to 26 km below the spawning site. With gillnets and trotline we collected an additional 24 fish (22–83 cm TL) and one sub-adult (103.5 cm TL) lake sturgeon in Portage Lake; four juveniles and the sub-adult were fitted with radio transmitters. Average daily linear movement of lake sturgeon varied from 0.3 to 1.6 km. Total linear distance traveled by sturgeon averaged 15.5 km over 83 days. Diel movements indicated that two juveniles moved into shallow (<5 m) inshore areas at night and into deeper (>7.5 m) offshore areas as light intensified.