Another invasive species found in Lake Superior

Published: February 26, 2018

Bloody red shrimp Photo courtesy of S. Pothoven, Great Lakes Environmental Research Laboratory

The words “bloody red shrimp” don’t exactly sound pleasant at the best of times, but the species’ name has become even more sinister to biologists’ ears since one of the shrimp was found in Lake Superior.

A single bloody red shrimp was found on the American side of the lake, near Duluth, Minnesota, in July, and was identified a few months later. The species originated from the Caspian Sea in Europe, and has since been found in every great lake except Lake Superior — until now.

“How it got here? We’re not really sure,” Doug Jensen, an invasive species specialist at the University of Minnesota’s Sea Grant Program, told the CBC.

“The finding really raises more questions than . . . answers.”

Environmental specialists aren’t ringing the alarm bells yet. The specimen — the only bloody red shrimp found in Lake Superior so far — was found dead, and it’s possible that it was already dead when it reached the lake, possibly being dumped by a cargo ship. However, if it does represent a new invasive species in the lake, it could be near impossible to get rid of.

“I’m not sure there’s any real effective management tool,” Jensen said.

As always, the best management practice for invasive species is to keep them from spreading, which boaters can do by cleaning their boats and changing filters before moving from one lake to another. In America, ocean-going cargo ships from other freshwater ports are required by the Coast Guard to flush out their ballast tanks with salt water before entering the Great Lakes, a process known as “swish and spit,” named after the common dentist’s commandment. The process has seemingly prevented any new species from entering the lakes since 2006. 

It’s unclear what effect the bloody red shrimp has on Great Lakes ecosystems. The species tends to avoid light, but emerges at night to eat zooplankton, which may reduce the number of zooplankton available to other fish. On the other hand, the shrimp themselves may become a food source for fish that also eat shrimp native to the lake.

Only time will tell if the bloody red shrimp has truly infiltrated Lake Superior, and what sort of effect it will have on the long term health of the Great Lakes. Scientists will consider to look into the issue, and in the meantime, the best the rest of us can do is clean our boats thoroughly and hope that that single shrimp was the only one of its kind to be found in Lake Superior.

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