Lake Sturgeon Movements Associated with Spawning in a Deepwater Great Lakes Connecting Channel

Lake Sturgeon populations remain at about 1% of pre-European settlement in the Great Lakes. The largest remaining free ranging population within the Great Lakes spawns in the Huron-Erie Corridor in headwaters of the St. Clair River near Port Huron (MI). In 2002-2004 14 Lake Sturgeon were implanted with ultrasonic transmitters to assess movements associated with spawning at the Port Huron Reef. Ten of 14 implanted Lake Sturgeon exhibited atypical migration patterns by migrating downstream from Lake Huron to spawn. The 4 remaining fish migrated back to either the lower St. Clair River or Lake St. Clair. Lake Sturgeon location data collected near the reef was used to identify spawning habitats during the spawn and staging areas prior to and after the spawn. Geo-referenced underwater video was used to determine the spatial extent and physical characteristics of habitats used. Fish used large underwater obstructions as refuge areas likely due to reduced current velocities. Deepwater (>15m) spawning habitat was dominated by pebble and cobble size substrates ranging from 2-50 cm diameter. No fine substrates were found throughout the 59 ha. spawning area. The downstream movement of fish from Lake Huron to the Port Huron reef suggests a behavioral trait that is not observed in other Lake Sturgeon populations within the Great Lakes.