Largemouth Bass Management in Wisconsin: Intra- and Inter-Specific Implications of Abundance Increases

Largemouth bass (LMB) are one of the most popular and intensively managed fish species in the United States.  Beginning in 1989, Wisconsin implemented more restrictive harvest regulations for LMB including greater minimum length limits, reduced bag limits, and a catch-and-release-only season during the spawning period across much of northern Wisconsin. We tested for trends in LMB relative abundance, growth, and angler catch and harvest in relation to LMB management policies from 1990-2011.  We also tested for potential walleye (WAE) responses to changes in LMB abundances.  Angler catch rates and electrofishing catch per unit effort of LMB > 8 and 14 inches increased significantly statewide.  Mean length of age-6 LMB decreased significantly statewide.  Release rates of LMB increased from about 80% in 1991 and then plateaued at over 96% from 2005- 2011. Concurrent with increases in LMB, adult WAE densities declined in lakes containing LMB.  Ongoing research is being conducted to test for interactions between LMB and WAE, and to test for additional environmental drivers, such as climate warming, that may be associated with increased LMB abundances. We recommend that management goals for LMB consider intra- and inter-specific consequences, particularly in water bodies where multi-species fisheries are desired.