Is There a Native Recipe for Controlling Invasive Common Carp?

Common carp (CARP) are a widespread invasive species and have been implicated in the degradation of native aquatic habitats and fisheries.  The Nature Conservancy’s, Emiquon Preserve floodplain lake restoration in Illinois used a largemouth bass biomanipulation in an attempt to control CARP through predation.  We observed that largemouth bass did not consume CARP, water clarity decreased, and CARP abundances increased over time.  Thus, we sought to examine ecosystem characteristics in other lakes where CARP are present, but not dominant.  Common carp have been present in Reelfoot Lake, Tennessee for over 100 years, yet have not caused negative ecosystem impacts.  We assessed the fish community and collected diets from largemouth bass, bowfin, and spotted gar in 2011 and 2012 on Reelfoot Lake to test whether fish species diversity and/or direct predation by these piscivores may limit CARP abundances and impacts. Bowfin and spotted gar abundances at Reelfoot Lake were equal to or greater than those of CARP.  Our bowfin, spotted gar, and largemouth bass diet analyses suggested that they may not be selecting for young-of year and/or juvenile CARP as a prey type. Thus, these species may not be directly influencing CARP via predation, but perhaps indirectly through other pathways.