Invasive Crab Concerns in Oregon

In mid-November, invasive river crabs were discovered in an Oregon river, raising worries for the Oregon Department of Fish and Wildlife. These crabs, which pose a threat to the state’s native crab species, might also lead to erosion and flood control issues.

This marks the second sighting of Chinese mitten crabs in Oregon rivers in 2025, with the initial report occurring in April.

On November 17, a crab was found in the Willamette River close to Portland, as noted by the ODFW.

Unlike Oregon’s native crabs that generally inhabit oceans and estuaries, mitten crabs spend their adult lives in freshwater and breed in brackish areas.

The crab discovered in November was captured alive in shallow water.

This particular crab was not returned to the river after being caught.

The name “Chinese mitten crab” comes from its distinctive hairy, mitten-like features on its claws.

According to ODFW, these crabs have a split between their eyes and four spines along their bodies. They are known for their burrowing habits, often causing damage to rock walls and riverbanks, which can exacerbate erosion and disrupt flood control systems.

Typically, they measure around 3 inches in width and exhibit a color range from brownish-orange to greenish-brown.

Furthermore, the agency indicates that mitten crabs can negatively affect local fish and crayfish by preying on native species, consuming fish eggs, and competing for resources.

It’s worth noting that possession and sale of these crabs are illegal in Oregon.

Officials are urging anyone who spots a crab resembling a mitten crab to report it by calling 1-866-INVADER or using the Oregon Invasive Species Reporting Hotline.

The ODFW is currently collaborating with the U.S. Fish and Wildlife Service, along with the Portland Lakes and Reservoir Center, to determine if more mitten crabs exist in the Willamette River.