Predicted Effects of Exploitation and Harvest Regulations on Lake Sturgeon Recruitment Potential in Multiple Segments of the Menominee River

The Menominee River that borders Wisconsin and Michigan currently supports some of the largest stocks of lake sturgeon associated with Lake Michigan and some of these stocks have supported hook-and-line fisheries for decades. Fishery managers are uncertain as to how angler harvest and changes in harvest regulations affect the sustainability of these lake sturgeon stocks. Our objectives were to use current biological information regarding the lake sturgeon stocks in three segments of the Menominee River to: 1) determine the potential effects of exploitation and minimum length limits on lake sturgeon recruitment potential and 2) determine if historic levels of exploitation reduced lake sturgeon recruitment potential. Our results suggest that minimum length limits ≥ 50 inches total length (TL) can be used to prevent overfishing of lake sturgeon, but overfishing is more likely to occur at length limits ≤ 55 inches, even if relatively low numbers of fish are harvested. Based on historic harvest information, overexploitation of lake sturgeon likely occurred within at least one river segment over the last decade, because in several years more than 25 fish ≥ 50 inches TL were removed, resulting in SPRs < 30%.