Midwest Fish & Wildlife Conference 2019

AUTHORS: Paige Wigren, Justin Chiotti, and James Boase – United States Fish and Wildlife Service, Alpena Fish and Wildlife Conservation Office – Detroit River Substation; Joseph Leonardi, Michigan Department of Natural Resources, Bay City Field Office; Tracy Galarowicz, Central Michigan University, Department of Biology

ABSTRACT: The installment of rock ramps to replace failing dams is a fairly new technique in the Midwest and little research has been done to assess the success of fish passage. In 2004, the structural condition of the Frankenmuth Dam was assessed and deemed to be in fair condition, but no longer functional, prompting officials to pursue dam removal. In order to maintain historic water levels in the impounded area above the dam, a thirteen-tier rock ramp was constructed in the fall of 2015 aimed at improving the connectivity and ecology of the Cass River watershed, a tributary to Saginaw Bay, MI. Prior to dam removal, electrofishing surveys were conducted in the spring and summer between 2010 – 2012 to record fish species composition above and below the existing dam. Post removal electrofishing surveys were conducted in the spring and summer between 2016 – 2018 with the goal of tagging fish downstream of the rock ramp and documenting changes in fish community composition. A total of 2,605 fish were tagged and 30 of these fish were recaptured upstream of the rock ramp. Since the construction of the rock ramp, 12 fish species not previously detected upstream have been captured, including freshwater drum, walleye, gizzard shad, flathead catfish, and round goby. Results indicate the rock ramp allows fish to access habitat upstream of the former dam, however passage is likely dependent upon river discharge during migration periods.