Estimating population size of largemouth bass and black crappie at The Nature Conservancy’s Emiquon Preserve prior to reconnection to the Illinois River

Prior to completion of the water control structure at The Nature Conservancy’s Emiquon Nature Preserve (Emiquon), a mark-recapture study was conducted on largemouth bass Micropterus salmoides and black crappie Pomoxis nigromaculatus to estimate the populations of both species. Largemouth bass > 150 mm and black crappie > 100 mm were captured using pulsed-DC electrofishing, fyke nets, and tandem fyke nets and double tagged using T-bar style clear tags. Results of this study show very large populations of both species, with populations of largemouth bass estimated at 21,090 (17,110-27,484) and black crappie estimated at 205,042 (91,198-490,563). Information gained in this study will allow Nature Conservancy managers to make informed decisions on future management actions and allow for potential evaluation of those management actions on two major components of the recreational fishery at Emiquon.