Lake sturgeon spawning habitat in the Big Manistee River, Michigan

Spawning sites of lake sturgeon Acipenser fulvescens were verified using egg collection mats in the Big Manistee River in northwestern lower Michigan. Photographs taken by a fixed-position underwater video camera were used to characterize the substrate at egg mat locations. A total of 3,913 lake sturgeon eggs were captured at two discrete spawning locations in 2003 and 2004. Spawning locations consisted of 34-44% cobble and 0.04-8% sand, and nonspawning locations consisted of 2-43% cobble and 0.16-7% sand. Shannon diversity indices describing substrate heterogeneity at spawning locations were statistically higher than those for nonspawning locations in 2003 (P = 0.002). Four spawning events (one in 2003 and three in 2004) were documented at water temperatures ranging from 11.1°C to 14.8°C and egg incubation periods ranging from 6 to 10 d. Depth at spawning sites was 1.5-3.0 m, average water velocity was 0.34-1.32 m/s, and near-substrate water velocity was 0.08-1.26 m/s. The topography of the Big Manistee River channel appears to have been altered by manipulated river flows, resulting in the development of barchans (ridges or shelves along the river bottom) in the region utilized for spawning. This study is the first to document lake sturgeon spawning success in the Big Manistee River and identify the specific characteristics of spawning bed material used as well as the presence of barchans that may produce eddies or turbulent irregular flows that affect egg dispersal and survival. © Copyright by the American Fisheries Society 2008