Signal Crayfish: First MN Encounter

Environmental & Science Education, STEM, Nature, Wildlife, Sustainability, Global Change

Ed Hessler

MPR's Dan Gunderson reported on "a new aquatic invasive species in Minnesota on November 3. The signal crayfish has been confirmed by the Department of Natural Resources in Lake Winona, near Alexandria, Minn." This story may have a good end but it will take some time and research before we know.

This species "is larger and more aggressive than native Minnesota crayfish and might outcompete native species for food and habitat." Dan Eaton, a DNR aquatic invertebrate biologist told Gunderson that "they can predate fish eggs. They can compete in terms of food items with the fish as well. So lots of potential impacts on the food web of the lake. 

"The DNR was alerted to the new invasive species by a commercial harvester who immediately notified the agency." This harvester deserves our deepest thanks.

Gunderson tells us that this crayfish can be imported in Minnesota for aquariums but requires a permit. In my view, given the record of this crayfish which is described in Gunderson's reporting and the Wiki entry, this doesn't seem to warrant such use. That it is illegal to release them into the wild, doesn't strike me as much of a deterrent. Accidents can happen as well. Gunderson describes the early monitoring work the DNR has done which will be ongoing.

It is an important read.

The MnDNR has an information sheet about signal crayfish.

I noticed that the StarTribune had a story about this potentially new invasive on November 4, 2023 and readers who subscribe likely read it or can read it on-line if you are a subscriber. It was written by Jennifer Bjorhus and is titled "This hefty fellow shouldn't be here."