Hairy, Invasive, Wall-Scaling Crabs Are Appearing in Oregon, and Officials Are Concerned

The Chinese mitten crab — identifiable by its furry, mitten-like claws, four side spines, and a notch between the eyes — was found in a river near Portland, Ore., wildlife officials confirmed.

According to a press release from the Oregon Department of Fish & Wildlife (ODFW) obtained by PEOPLE, the medium-sized crab, which is not native to the United States, is typically 3 inches wide and ranges from brownish-orange to greenish-brown.

The recent sighting of the invasive crustacean occurred in shallow water of the Willamette River on Monday, Nov. 17. The crustacean was removed from the river alive by hand and will not be returned to the wild. CBS News noted that the Chinese mitten crab can scale walls up to 13 feet tall.

November’s sighting marks the state’s second confirmed mitten crab sighting in 2025; another Chinese mitten crab was discovered in April at a different location in Oregon (the Lower Columbia River). The two encounters are “concerning” for ODFW experts, who are working to determine whether the invasive species is establishing a population in Oregon’s waterways.

ODFW biologists are partnering with the U.S. Fish and Wildlife Service, Portland State University’s Center for Lakes and Reservoirs, and the Oregon Invasive Species Council to search for additional mitten crabs in the Willamette. Their efforts include installing artificial habitats that could attract mitten crabs, testing water and sediment samples for environmental DNA, and conducting shoreline walks to look for molted shells.

PEOPLE reached out to the Oregon Department of Fish & Wildlife for comment.

According to ODFW, the invasive species poses multiple risks to Oregon’s natural ecosystems. Chinese mitten crabs burrow into levees, dikes, and stream banks, increasing erosion and threatening flood-control systems.

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The crustaceans also prey on native species, eat fish eggs, and compete with local fish and crayfish for food. Because they are illegal to possess or sell in Oregon, officials say unlawful imports tied to the food trade remain a concern — and any suspected sales should be reported.

ODFW is also asking people to report any potential sightings of the Chinese mitten crab to the agency. ODFW noted that the Chinese mitten crab, which has claws that appear furry on the outside, can look similar to Oregon’s native hairy shore crab, which has hairy patches on the inside of its claws.

Sightings can be reported online through the Oregon Invasive Species “Report an Invader” hotline form or by calling 1-866-INVADER. Photographs are also highly encouraged.