Muskellunge Management: Fifty Years of Cooperation Among Anglers, Scientists, and Fisheries Biologists

Long-Term Effects of a Forty-Inch Minimum Length Limit on Muskellunge in Wisconsin Lakes [Extended Abstract]

Timothy D. Simonson

doi: https://doi.org/10.47886/9781934874462.ch47

Relatively high minimum length limits are commonly imposed on Muskellunge Esox masquinongy fisheries to protect adults to full maturity and provide trophy fishing opportunities. Evaluations of length-limit effects on Muskellunge populations are uncommon and have been either of relatively short duration (<10 years) or were focused on individual waters. Brenden et al. (2007) predicted that moderately high minimum length limits (36, 40, and 45 in [1 in = 2.54 cm]) would all result in more memorable-sized (42 in and larger) fish. Cornelius and Margenau (1999) concluded that increasing the minimum length limit from 30 to 40 in apparently increased abundance and mean length of Muskellunge, based on a long-term evaluation of Bone Lake, Wisconsin, compared to nearby Deer Lake, Wisconsin.

Beginning in 1991, the Wisconsin Department of Natural Resources (WDNR) imposed a 40-in minimum length limit for Muskellunge on selected waters to evaluate the usefulness of this regulation. Over a 3-year period, from 1991 to 1993, the minimum length limit was increased from 32 in to 40 in on 47 waters across Wisconsin. The goals of the 40-in minimum length limit were to (1) increase abundance of Muskellunge (via increased natural reproduction and protection of adults), and (2) restore trophy potential of waters by improving size-structure (Margenau and AveLallemant 2000). Margenau and AveLallemant (2000) evaluated effects of the 40-in minimum length limit across several lakes in Wisconsin but found no significant responses 5 years after implementation. They concluded that an extended time may be required to evaluate Muskellunge population responses to management actions. Further, with recent, widespread increases in voluntary catch and release of Muskellunge, relative benefits of minimum length limits are uncertain.