The Minnesota Department of Natural Resources has confirmed the presence of signal crayfish, an invasive non-native species, in Lake Winona, adjacent to Alexandria in Douglas County. This is the first confirmation of signal crayfish in Minnesota waters.
A commercial harvester contacted the DNR after trapping two signal crayfish in Lake Winona. Since the first catch, the harvester has found eight additional signal crayfish in Lake Winona. The DNR followed up with trapping in Lake Winona and in two adjacent connected lakes but did not capture additional signal crayfish.
One female was among the 10 adult signal crayfish captured and removed from Lake Winona. At this time, there is no evidence of reproduction; no eggs or juveniles have been found.
Signal crayfish are larger and more aggressive than Minnesota crayfish and the invasive rusty crayfish. They eat aquatic plants, detritus, fish eggs, smaller crayfish species and other beneficial native invertebrates. Signal crayfish might outcompete native species for food and habitat. Signal crayfish can spread between connected waterways or be transported by people. They can also crawl over land at night and during wet weather.