A fisherman in Oregon recently reeled in an unusual sea creature with hairy claws — and wildlife officials have confirmed it's an invasive species.
The Chinese mitten crab was caught on April 22 from the Lower Columbia River near Tongue Point, the Oregon Department of Fish and Wildlife announced in a news release. The Columbia River, which separates Oregon and Washington, had not previously recorded the presence of this species.
The fisherman noticed the crab looked "unusual" and brought it to wildlife staff. A biologist later confirmed it was an invasive Chinese mitten crab, marking the first confirmed sighting of the species in the Pacific Northwest, officials said.
Chinese mitten crabs are classified as a prohibited species because they caused "significant infrastructure and ecological damage" when they appeared in San Francisco Bay in the 1990s, officials noted. Due to the potential threat they pose, wildlife authorities urged the public to report any sightings.
The crab is recognizable by its distinctive hairy claws, a notch between its eyes, and four spines on its hard shell, officials explained. Its color can range from brownish-orange to greenish-brown.
Although mitten crabs primarily live in freshwater, adults migrate to saltwater to reproduce. "Newly hatched larvae are in open saltwater in bays and estuaries and fully molted juveniles are found in brackish and freshwater areas within a few miles upstream of saltwater," officials said.
It remains unclear how the male crab found its way into the river. Officials suggested it may have been illegally introduced or arrived via ballast water from a large ship. Ballast water, used to stabilize vessels, can sometimes release invasive species when discharged into new environments, according to ClearSeas.
Biologists are now working with other agencies to investigate whether more mitten crabs are present in the Columbia River. Wildlife officials encouraged anyone who encounters a mitten crab to report it online.
