Response of fish assemblages to restoration of rapids habitat in a Great Lakes connecting channel

Rapids habitats are critical spawning and nursery grounds for multiple Laurentian Great Lakes fishes of ecological importance such as lake sturgeon, walleye, salmonids. However, river modifications have destroyed important rapids habitat in connecting channels by modifying flow profiles removing large quantities cobble gravel that preferred substrates several fish species. The conversion to slow moving waters has altered assemblages decreased the success lithophilic St. Marys River is a channel which majority been lost. was restored at Little 2016 recover this river. During restoration, substrate were recovered habitat. We sampled community (pre- post-restoration), focusing on age-0 order characterize response assemblage particularly species (e.g. whitefish, Atlantic salmon). Following we observed 40% increase catch per unit effort, increased presence rare species, shift structure (higher relative abundance Salmonidae, Cottidae, Gasterosteidae). also “transition” period 2017, markedly different from pre- post-restoration dominated Catostomidae. Responses target mixed, with salmon abundance, first documented walleye no sturgeon or Coregoninae.