Integrated Pest Management of the Common Carp in the American Midwest

The common carp is one of the most abundant and destructive invasive fish in both North America and Australia where it has severely damaged hundreds of thousands of hectares of shallow-water ecosystems.  Carp control in North America has traditionally attempted to use rotenone (a nonspecific fish poison) and water-drawdowns, but success has been elusive and short-lived. Recently, we discovered that adult carp aggregate in the winter, and that carp population abundance is often driven by seasonal fluctuations in the numbers of egg-eating native fish in outlying regions of many Midwestern watersheds (Bajer & Sorensen 2010). These insights have allowed us to initiate an experimental integrated pest management (IPM) scheme that focuses on targeted adult removal using Judas fish and suppressing carp recruitment by re-balancing native fish populations in carp spawning habitat. We have been able to suppress carp populations to about 10% of their initial levels in three lakes for five years at modest cost. Significant improvements in water quality have also been noted and there has been no recruitment.  (Minnesota Environment and Natural Resources Trust Fund, Riley Purgatory Bluff Creek Watershed District, Ramsey-Washington Metro Watershed District and Invasive Animals Cooperative Research Centre).