A commercial fisherman working the Lower Columbia River near Astoria, Oregon, recently hauled in something that didn’t belong. What he’d netted wasn’t just another catch — it was a Chinese mitten crab, an invasive species banned in Oregon. This marked the first confirmed appearance of the notorious crab in the Pacific Northwest, sparking immediate concern among wildlife officials across state lines.

“This is big news,” Matthew Hunter, a shellfish biologist with the Oregon Department of Fish and Wildlife (ODFW), told KGW. “It’s an invasive species, and we already have endangered fish species listed in the Columbia.”

Photo: Wikimedia Commons / Bj.schoenmakers, License: CC0 1.0

A Chinese mitten crab was caught in the Columbia River for the first time.

An Invasive History Repeats

Chinese mitten crabs (*Eriocheir sinensis*) are no strangers to American waters. Native to East Asia, they first gained a foothold in California’s San Francisco Bay during the 1980s. At their peak in the late ’90s, commercial fishermen were pulling in hundreds of thousands each year.

“It was spectacularly abundant. A true outbreak,” biologist Greg Ruiz told the Smithsonian Magazine.

The crabs damaged levees, clogged fish salvage facilities, and displaced native species. Despite eradication efforts in California, the crabs have spread to the East Coast, Great Lakes, and Gulf of Mexico in isolated incidents. But until now, they hadn’t been found in the Pacific Northwest.

Photo: Wikimedia Commons / Bj.schoenmakers, License: CC0 1.0

The crab is an invasive species banned in Oregon.

How Did It Get Here?

The exact pathway into the Columbia remains unclear. Wildlife experts suspect the crab may have arrived as larvae in ballast water discharged from a ship — a common vector for aquatic invasive species. Another possibility is illegal release, which has been known to happen due to the crab’s popularity as a delicacy in some parts of Asia.

“It could have come in the ballast water, or it could have been shipped and dumped,” Hunter told OPB. “We’re not sure if this is a one-off or one of many that are out there.”

The individual crab was a large male caught near Tongue Point, a brackish area ideal for this species, which requires saltwater to reproduce but spends most of its life in freshwater. The fisherman who caught it recognized the species, contacted ODFW, and delivered the crab directly to their office in Astoria.

It was discovered near Tongue Point, east of Astoria.

Why Officials Are Worried

Chinese mitten crabs are tough survivors and skilled escape artists. The U.S. Bureau of Reclamation notes they can live for over a week without water and are capable of scaling vertical concrete barriers up to 13 feet high. They’ve even been observed bypassing lock systems and climbing fish ladders.

More troubling is their impact. Their burrowing behavior weakens stream banks and infrastructure. They also consume native fish eggs, aquatic grasses, and invertebrates, creating ripple effects through the ecosystem. Their ability to walk over land between bodies of water only increases the risk of further spread.

According to Yahoo News, the mitten crab’s presence in the Columbia could threaten already vulnerable fish populations and increase the cost of infrastructure maintenance.

Chinese mitten crabs can survive out of water for over a week.

Response Efforts Underway

ODFW and its partners — including the Washington Department of Fish and Wildlife and NOAA — are racing to determine if more mitten crabs are in the region. They plan to set trap lines and collect environmental DNA samples to detect any unseen populations. Early detection is critical, as once established, these crabs are notoriously difficult to remove.

Public involvement is also key. Wildlife officials are asking anyone who spots a mitten crab to report it immediately. “Snap photos, note the location, and report the sighting,” ODFW urges via the Oregon Invasive Species Council.

Hunter stressed the importance of public vigilance.

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

Their presence threatens endangered fish in the Columbia.

One Crab, Many Questions

For now, the mitten crab caught in April sits in a freezer at ODFW’s office. But that single specimen is prompting a flurry of research, outreach, and concern.

“This discovery could just be the tip of the iceberg,” warned Smithsonian Magazine. As wildlife managers continue their work, the hope is that this sighting remains an isolated incident — not the start of a new invasion.