Evaluation of Largemouth Bass Minimum and Slot Length Limit Regulations

Abstract

Beginning in 1982, minimum and slot length limit regulations for largemouth bass (Micropterus salmoides) were enforced on four lakes in southeast Wisconsin. Beulah and Rockland Lakes had a 305 - 406 mm slot length limit, and Pretty and Browns Lakes had a 406 - mm minimum length limit. Changes since 1980, in the largemouth bass and panfish, primarily bluegill (Lepomis macrochirus), populations and fisheries one year after imposition of the regulations were assessed. Since the regulations, largemouth bass mortality Decreased significantly in Pretty Lake, and mean length increased significantly in Rockland Lake. Bluegill Relative Weight (Wr) increased in all lakes but Pretty Lake, where it decreased significantly. Largemouth bass Wr remained in the satisfactory range (95-105%) in all the lakes. These changes were expected, and I think more time is necessary for the Stock Density (PSD) of both predator and prey fall within recommended ranges. Angler exploitation of largemouth bass in Rockland Lake decreased from 87% in 1980 to 31% in 1982. Fishing pressure (hrs/ha) increased in 3 of the lakes in 1982, and the length limit regulations reduced the number of largemouth bass harvested from the protected size ranges. Mean length harvested, and catch and harvest rates of bluegills increased significantly for all lakes. However, these changes were inconsistent for largemouth bass.