Invasive Crayfish Species Discovered in Douglas County Lake

(KNSI) — A nonnative crayfish species has been discovered in Lake Winona near Alexandria in Douglas County.

A commercial harvester contacted the Minnesota Department of Natural Resources after trapping two signal crayfish. The DNR followed up with trapping in Lake Winona and two adjacent connected lakes but did not capture additional signal crayfish. One female was among the 10 adults captured and removed from the water. Officials say no eggs or juveniles have been found.

This is the first confirmation of signal crayfish in Minnesota waters. This species is larger and more aggressive than native species and the invasive rusty crayfish.

They eat aquatic plants, other organic matter, fish eggs, smaller crayfish species and other beneficial native invertebrates and 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.

Signal crayfish are bluish-brown to reddish-brown in color, with large, smooth claws and a smooth carapace – the protective covering over their head and midsection. They have a white or pale blue-green patch near their claw hinge, which looks like a signal flag.

Anyone who sees one is asked to contact the DNR.

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