Effects of a Reduced Daily Bag Limit on Bluegill Size Structure in Wisconsin Lakes

Abstract

AbstractThis study evaluated the effect of reduced aggregate panfish bag limits (from 25 to 10) on the size structure of Bluegill Lepomis macrochirus populations in seven natural lakes in Wisconsin. For assessing the overall significance of treatments, each treatment lake was paired with a control lake in which the regulation was not implemented. Across all lakes, mean total length (TL) of sampled Bluegills was significantly greater in treatment lakes than in control lakes after the regulation was implemented: on average, mean TL increased by 20.3 mm. However, efficacy of reduced bag limits varied substantially across lakes as mean TL improvements ranged from −5.1 to 63.5 mm in individual lakes. This variation could be strongly explained (R2 = 0.81) by lake Secchi depth (lakes with reduced water clarity showed larger improvements in mean TL, R = −0.62) and regulation duration (size structure improved continuously with time after the reduced daily bag limit was implemented, R = 0.75). Reduced bag limits are a useful tool for providing improvements to Bluegill size structure in Wisconsin lakes, but would be most effective in more productive waterbodies and will require substantial time investments after implementation.Received September 18, 2014; accepted December 18, 2014