This post was originally published on here
An invasive freshwater crab species that can cause erosion problems and damage flood control as well as threaten native crab species in Oregon was captured in a river in mid-November, sparking concern for the Oregon Department of Fish & Wildlife.
This is the second report of a Chinese mitten crab found in an Oregon river in 2025, with the first being in April.
The most recent crab was found in the Willamette River near Portland, on Nov. 17, ODFW said.
Oregon’s native crab species live in the ocean, bays and estuaries, while mitten crabs spend their adult life in freshwater and breed in brackish waters, the agency said.
The Chinese mitten crab captured in November was found in shallow water and caught by hand, alive.
It wasn’t released back into the river.
Chinese mitten crabs get their name because of hairy mitten-like features on the outside of their claws.
They also have a notch between their eyes and four spines on the sides of their bodies, ODFW said.
The crab species are known to burrow into rock walls, levees or stream banks, which can increase erosion and damage flood control and water supply systems.
The crabs are medium-sized crabs, about 3-inches wide, and they can vary in color from brownish orange to greenish brown, according to ODFW.
The department said they prey on native species, consume fish eggs and compete for food, potentially impacting native fish and crayfish populations.
Possessing and selling mitten crabs in Oregon is illegal.
The department is asking anyone that sees a crab that resembles a Chinese mitten crab to report it at 1-866-INVADER or use the online Oregon Invasive Species reporting hotline.
Oregon Fish & Wildlife said it’s working with U.S. Fish and Wildlife Service, Portland State’s Center for Lakes and Reservoirs and the Oregon Invasive Species Council to find out if other mitten crabs are in the Willamette River.
