Fish Spawning and Nursery Habitat Assessments in the St. Clair-Detroit Rivers System

Ecosystem management and restoration require sound scientific information derived from monitoring and assessment programs to inform decision making and assess progress toward goals.  The international St. Clair – Detroit Rivers System (SCDRS) has a long history of environmental perturbations with numerous programs completed or ongoing to resurrect native fish populations by restoring spawning habitat. Intensive investigations of the extent and magnitude of fish spawning, egg deposition, and larval fishes over the past 5 years revealed that habitat for lithophilic spawners can be restored as evidenced by widespread use of artificial spawning reefs by Walleye Sander vitreus, Lake Whitefish Coregonus clupeaformis, Lake Sturgeon Acipenser fulvescens, and Catostomidae.  Extensive spawning by Walleye, Lake Whitefish, and suckers also occurred on native substrates in both rivers, with about an order of magnitude higher egg densities occurring in the Detroit River.  Abundance of larval fishes was also higher in the Detroit River, due to increased spawning in that river, as well as production of Yellow Perch Perca flavescens in Lake St. Clair.  The larval fish community in the St. Clair River consisted of resident spawners, but also contained a large contribution of fishes drifting from Lake Huron.