Is This Adorable Invasive Crab a Threat to Michigan?

Invasive species tend to be anywhere from a simple nuisance to downright dangerous. But this crab species couldn’t possibly pose a threat to Michigan, right? After all, it’s adorable and its name should suggest it’d be a friend of the Mitten State.

The Chinese Mitten Crab is a species native to the waters of Southeast Asia. However, whether by intentional release or ballast water introduction, it has been spotted in American waters over the years.

Although its name could suggest the species is the state crustation for Michigan, it is far from it.

The mitten crab gets its name from the appearance of its pincers, which have a “fuzzy” appearance in adulthood. Younger mitten crabs lack this characteristic but do have a notch between the eyes and lateral spines on each side of their bodies.

Why Are Mitten Crabs Invasive?

There are a variety of reasons plants, animals and insects can be labeled as invasive, but the most common means is by disrupting the local ecosystem. Mitten crabs manage to do this in a variety of ways.

According to the The Michigan Invasive Species Program:

The appetite of the mitten crab can completely alter a food web and may allow them to out-compete native crabs, crayfish, and mussels for resources. Burrowing activity significantly decreases stream bank stability and increases erosion. Mitten crab can consume fishing bait, damage or consume catch, damage fishing nets, and clog pumps, screens, and water intake structures. They are also an intermediate host of the Oriental lung fluke, which has not been found in any mitten crabs collected in the U.S.

Are They Here in Michigan?

Mitten crabs are one of the many invasive species the state monitors, however, they are not currently in Michigan. But, that can change.

Recently, mitten crabs have been spotted in New York state in the Hudson River and Long Island Sound. While that is plenty far away from us here in Michigan, it’s worth monitoring that they don’t wash up on the shores of one of the Great Lakes.

The species has had quiet interactions with Michigan in the past. In 2007, it was rumored mitten crabs had found their way into the Detroit River through Lake Erie, where one was allegedly caught. It’s worth noting that the state didn’t technically acknowledge the reports.

Mitten crabs are most commonly spotted in the San Francisco Bay where they have an established population. Other notable locations include the Chesapeake Bay, Delaware Bay, Hudson River, Columbia River, and Mississippi River.

What If You Spot A Mitten Crab?

First and foremost, it’s important to report a sighting to the Midwest Invasive Species Information Network here.

New York officials suggest freezing the species if you capture it, though Michigan officials make no such suggestion.

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