A Largemouth Bass Closed Fishery to Control an Overabundant Bluegill Population in a Wisconsin Lake

Abstract

ABSTRACT We studied Round Lake, in central Wisconsin, to determine if predator-prey balance could be restored by protecting predator populations. In January 1986 the 28.8 ha lake was closed to fishing for gamefish: largemouth bass (Micropterus salmoides), northern pike (Esox lucius), and walleye (Stizostedion vitreum). Panfish seasons remained open. Largemouth bass and bluegill (Lepomis macrochirus) were the predominant predator and prey in Round Lake, with bluegill comprising 58 % by weight of the largemouth bass diet from 1984 to 1991. Numbers and biomass of stock length (200+ mm) largemouth bass increased following closure of the lake to predator fishing, and there was a reduction in the population of stock-to-quality (80–149 mm) bluegill. Bluegill biomass remained relatively stable from 1984 to 1992, while bluegill numbers decreased. Bluegill relative weight (Wr) and longevity increased. Increased numbers of quality (150+ mm) bluegill by 1988 resulted in higher fishing pressure and panfish harvest.