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Invasive Chinese Mitten Crab Found in Willamette River Near Portland — Officials Urge Reports

01:15 AM, 12/04/2025
Invasive Chinese Mitten Crab Found in Willamette River Near Portland — Officials Urge Reports

Oregon officials confirmed a Chinese mitten crab was removed alive from the Willamette River near Portland on Nov. 17, 2025—the state's second confirmed sighting this year. Agencies including ODFW, the U.S. Fish and Wildlife Service and Portland State University are expanding surveillance with traps, eDNA testing and shoreline searches. The species can burrow into levees, prey on native wildlife and compete with local species; the public is urged to photograph and report any sightings to 1-866-INVADER or via the Oregon Invasive Species "Report an Invader" form.

Oregon wildlife officials confirmed that a Chinese mitten crab (Eriocheir sinensis) was found and removed alive from shallow water in the Willamette River near Portland on Nov. 17, 2025. This is the state's second confirmed sighting this year and has prompted expanded monitoring to determine whether a local population is becoming established.

Identification: The medium-sized crab is typically about 3 inches wide and ranges from brownish-orange to greenish-brown. Key identifying features include furry, mitten-like claws, four lateral spines on the carapace and a distinct notch between the eyes. These crabs are also capable of climbing vertical surfaces—reports indicate they can scale walls up to 13 feet high—allowing movement between waterways and human structures.

Why officials are concerned

Chinese mitten crabs can damage both natural and built environments. They burrow into levees, dikes and stream banks, which can accelerate erosion and undermine flood-control structures. Ecologically, they prey on native species, consume fish eggs and compete with local fish and crayfish for food. Because possession and sale of mitten crabs are illegal in Oregon, unlawful imports tied to the food trade remain a concern.

What authorities are doing

Oregon Department of Fish and Wildlife (ODFW) biologists are working 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 deploying artificial habitat traps, collecting water and sediment for environmental DNA (eDNA) analysis, and conducting shoreline surveys to find live animals or molted shells.

How the public can help

If you spot a crab that may be a Chinese mitten crab, take clear photographs from multiple angles (including the claws and top of the carapace), note the exact location, date and water depth, and report the sighting promptly. Do not release a captured crab back into the water. Reports can be submitted through the Oregon Invasive Species "Report an Invader" online form or by calling 1-866-INVADER. Photographs are highly encouraged to help experts confirm identifications.

Note: The Chinese mitten crab can be confused with Oregon's native hairy shore crab; the native species has hair on the inside of its claws, while the mitten crab's claws appear furry on the outside. Careful photo documentation helps distinguish between them.

Source: Oregon Department of Fish and Wildlife and partner agencies.

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