The red swamp crayfish is a relatively new aquatic invasive species to Wisconsin. The first and so far only two findings were in southeastern Wisconsin in the fall of 2009. Esquire Estates Pond is located in the town of Germantown, Washington County and Sam Poerio Park Pond is in Kenosha, Kenosha County. The DNR was contacted when the neighbors of Esquire Estates began finding ‘small lobsters’ in their yards, and in some cases, their garages. While this sounds like a good opportunity for a crawfish boil, these crayfish cause a lot of harm to the native wildlife. Red swamp crayfish feed on almost anything and everything, which can lead to declines in the amount of aquatic plants (important habitat for many fish and insects), snails, insects, native crayfish and amphibians. Since it is a new and prohibited species in Wisconsin, the best control techniques are still being determined. Red swamp crayfish pose some unique challenges since they are aquatic but also excavate burrows in the bank. Upon verification of this new invasive species, quick action was taken to contain the crayfish and prevent spread to nearby waters. The DNR constructed containment fencing around both ponds and began intensively trapping the crayfish using modified minnow traps. Once the population sizes were lowered through trapping, a chemical treatment was applied. While reducing the numbers greatly, the chemical method did not eradicate the populations as some crayfish survived in burrows. A more intensive approach was taken in 2011 for Sam Poerio Park Pond. The pond was drained, the banks with burrows scraped and compacted and the pond completely filled in. Preliminary monitoring this spring has shown the Sam Poerio Park Pond project to be successful. DNR staff will continue to monitor nearby ponds and streams over the next several years to verify this. For the Esquire Estates Pond, the Department is currently working on an eradication plan which will be implemented this fall. A significant amount of time and money, in the order of hundreds of thousands of dollars, has been spent dealing with this new aquatic invasive species. Humans are thought to be the main method for red swamp crayfish introduction, which is why it important to obey the laws surrounding crayfish in Wisconsin. It is illegal to possess, transport, transfer or introduce any live non-native crayfish in Wisconsin, with the exception that rusty crayfish can be used as bait on the Mississippi River and kept in aquariums. If crayfish are bought on-line, in pet stores or from out of state they are most likely non-native and illegal to possess.
Blog post written by Erin Vennie-Vollrath & Scott Van Egeren
June is Invasive Species Awareness Month. For more information about invasive species, special events, and ways to get involved, visit invasivespecies.wi.gov/awareness.