Movements and distribution of adult Lake Sturgeon from their spawning site in the St. Clair River, Michigan

Abstract

Summary Lake Sturgeon Acipenser fulvescens were studied to determine spawning migrations, seasonal movement patterns and habitat use in the St. Clair River and Lake St. Clair. Ultrasonic transmitters were successfully implanted in 15 sexually mature adult fish during spawning periods in 1997–1999. Telemetry data, along with GIS software, were used to determine where Lake Sturgeon resided in Lake St. Clair following implantation. Movement information collected from tagged Lake Sturgeon from May 1997–October 2000 revealed three patterns. Following implantation, 73% of the fish (four females and seven males) moved downstream from the St. Clair River to Lake St. Clair, 13% of the fish (one female and one male) were presumed to have moved upriver to Lake Huron, and 20% of the fish (one female and two males) remained in or returned to the St. Clair River for at least 1 year. The fish that moved into Lake St. Clair were found most often in an area near the St. Clair River Delta, at depths of 4–6 m (>98% of observations). Fish that remained in the St. Clair River were commonly found (>84%) at depths between 9 and 18 m. Four females and three males returned to the spawning site in the St. Clair River in subsequent spawning seasons. Females returned at intervals of 1–3 years and males at 1–2 years. For all invertebrates tested, only Ephemeroptera density was a significant predictor of Lake Sturgeon presence/absence in Lake St. Clair.