Effects of hurricane-induced hydrilla reduction on the largemouth bass fishery at two central Florida lakes

Lakes Weohyakapka and St. Johns Water Management Area, Florida, experienced severe impacts from multiple hurricanes in August and September 2004, resulting in the loss of all submersed aquatic vegetation, primarily hydrilla (Hydrilla verticillata). We assessed at both lakes changes in largemouth bass (Micropterus salmoides) population size distribution, recreational fishing effort and success, angler expenditures, and catches of trophy fish in relation to disparate levels of hydrilla coverage for prehurricane (1999-2004) and posthurricane (2005-2009) periods. Tests revealed significant differences at both lakes in the population size distribution between prehurricane (high percentage coverage of hydrilla) and posthurricane (no hydrilla) periods. At both lakes, the population size distribution comprised more juvenile (age-1) largemouth bass before the hurricanes, indicating that a decline in recruitment strength coincided with the absence of hydrilla posthurricanes. Declines in directed fishing effort, angler expenditures, and angler catches of trophy-sized fish also occurred following the absence of hydrilla posthurricanes. These findings demonstrate an important link between radical changes in hydrilla coverage with recruitment of juvenile largemouth bass and the strength of the largemouth bass fishery. The Florida Fish and Wildlife Conservation Commission recently adopted a new agency position on hydrilla management that allows flexibility regarding waterbodies with limited or absent native submersed vegetation, recognizing that hydrilla at a low to moderate coverage can be beneficial to fish and wildlife.