Seventy-Year Retrospective on Size-Structure Changes in the Recreational Fisheries of Wisconsin

Andrew L. Rypel, John Lyons, Joanna D. Tober Griffin, and Timothy D. Simonson


To identify past successes and future opportunities for improved fisheries management in Wisconsin, we synthesized sizestructure information on 19 gamefish species from 1944 to 2012, incorporating data on more than 2 million measured individuals. Since the 1940s, mean and mean maximum sizes of five “gamefish” species (Lake Sturgeon Acipenser fulvescens, Largemouth Bass Micropterus salmoides, Smallmouth Bass M. dolomieu, Northern Pike Esox lucius, and Sauger Sander canadensis) have stayed fairly stable, and one (Muskellunge E. masquinongy) initially dropped and then rebounded—most likely as a product of increased catch-and-release fishing and restrictive harvest regulations. In contrast, four “panfish” species (i.e., Bluegill Lepomis macrochirus, Green L. cyanellus, Yellow Perch Perca flavescens, and Black Crappie Pomoxis nigromaculatus), which have not received the same conservation management attention, have experienced substantial and sustained erosions in size over the same period. Regulations for many species and species complexes have been cyclical over time, illustrating the challenge of consistently managing fisheries. Our long-term retrospective analysis was effective at identifying new opportunities for improved fisheries management in Wisconsin (i.e., panfish management). We therefore encourage other big data retrospective approaches within and across regions to identify past successes and future opportunities in other fisheries management programs.

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