Invasive Species of the midwest: A Soil Sci 101 Project

Overview

Unlike the other species we decided to study, the rusty crayfish is actually native to North America–the southern US, to be exact. It is suspected that they were transported and released by anglers that were using them as bait into lakes and rivers in Wisconsin and Minnesota. This freshwater species has many native look-alikes, making detection and population estimations quite challenging. The only visible difference between the rusty crayfish and native populations is the distinctive rust-red patch just above the tail (St. Croix). This species is more aggressive than native crayfish such as the northern clearwater, outcompeting for food and shelter. This, combined with their higher fecundity, leads to native species being forced into open water where they make easy prey, further depleting their numbers. Once a population is established, it is exceedingly difficult to remove rusty crayfish as any methods of eliminating them would also affect native species (St. Croix). As such, the most effective method for eliminating rusty crayfish is to trap large colonies of crayfish and painstakingly sort through the group, looking for the red patch to remove individuals one at a time.

Quick Facts!

• Native to southern US, invasive in Wisconsin and Minnesota
• Transported and released by anglers who used them as bait
• Very aggressive—out compete and threaten native crayfish
• Also capable of hybridizing with native crayfish, further depletes native genetics
• “Clip” food instead of nibbling—destroys a lot of vegetation while eating
• Increases erosion of sediment
• Recorded in 80 bodies of water in Wisconsin (Wisconsin DNR)
• Because similar to native populations, pesticides and chemicals do not work to get rid of these crayfish.
• Have characteristic “rusty” patch just above tail—juveniles do not have them and are indistinguishable from native crayfish