Crayfish native to Pacific Northwest found in lake near Alexandria

An invasive species has been confirmed in one of Minnesota’s Douglas County lakes.

According to the Minnesota Department of Natural Resources, the signal crayfish has been found in Lake Winona. So far, the agency has found 10 of the animals in the lake, including one female, but says so far, they haven’t found any evidence of reproduction, adding they didn’t find any eggs or juveniles.

DNR officials say the signal crayfish are not only larger than native crayfish and the invasive rusty crayfish but are also more aggressive than those species. They can spread between connected waterways, crawl over land at night and during wet weather, and can also be spread by people.

The agency says the animals may outcompete native species for food and habitat, saying they eat aquatic plants, fish eggs, smaller crayfish species and other native invertebrates. It is native to the Columbia River drainage in Washington, Oregon, Idaho and British Columbia. The DNR says the signal crayfish is imported and sold through the pet trade and to schools by biological supply houses. It adds it’s illegal to import the species into Minnesota without a permit.

As shown in the photo, signal crayfish range from blueish brown to reddish-brown in color, have large and smooth claws, a white or pale blue-green patch near the claw hinge, and also a smooth carapace – the covering over their head and midsection.

Additional information about the signal crayfish can be found by CLICKING HERE.

No other water bodies in Minnesota have been reported to have the crayfish in them. A commercial harvester notified the DNR after trapping two of the animals, and since then, the agency says the harvester found eight additional signal crayfish.

If you think you’ve seen the signal crayfish or other invasive species, you’re asked to submit information by CLICKING HERE or by CLICKING HERE.