Oregon and Washington wildlife officials are asking people to keep an eye out for hairy-clawed mitten crabs in the Columbia River.

In April, a commercial fisher caught a Chinese mitten crab along the river that borders both states. It’s the first recorded instance of this species in the Pacific Northwest, besides a Japanese mitten crab caught in the same area in 1992.

“We’re not sure if this is a one-off or if this is just one of many that were out there,” Oregon Department of Fish and Wildlife shellfish biologist Matthew Hunter said.

This mitten crab could have come from ballast water released by cargo ships, Hunter said. Or, someone who had the crab shipped from overseas could have tossed it into the river.

Mitten crabs burrow in freshwater rivers, lakes and estuaries. When there are too many, they can damage dams and levees, or destabilize embankments. Hunter recommends people contact the wildlife department if they find something that looks like a mitten crab.

“Because the more information we get on whether there’s any abundance of these, the better off we are,” Hunter said.

Chinese mitten crabs are native to countries in East Asia. Their mitten-shaped claws are thick and hairy, and their legs are twice as long as their main shell, called a carapace.

These long-legged crabs are considered invasive in parts of Europe, and they’ve been found in some parts of North America. They were once considered invasive in the San Francisco Bay Area in the 1990s, but their numbers dropped in recent decades after California launched an expensive eradication campaign.

This mitten crab was caught a few miles east of Tongue Point, near Astoria, where the freshwater of the Columbia River starts to get salty.

Hunter worries this region could be vulnerable to a mitten crab infestation, since the crustaceans prefer areas where they could easily move between fresh and salty water. Mitten crabs spend most of their adult lives in freshwater and migrate to saltwater to spaw.

Unlike Oregon’s native Dungeness crabs, mitten crabs are difficult to catch. Since they are opportunistic omnivores, they’re less inclined to be lured into cages baited with meat. Catching mitten crabs usually requires nets, so eradicating them would be difficult.

News Source : https://www.opb.org/article/2025/05/05/chinese-mitten-crab-oregon-washington-/