Destructive, Invasive Crab Found on N. Oregon Coast, Officials Ask Public's Help

Published 04/27/25 at 8:25 p.m.
By Oregon Coast Beach Connection Staff

(Astoria, Oregon) - As Oregon and Washington deal with the invasive green crab, Oregon wildlife officials are now concerned about a certain species of crab known to damage ecosystems in the U.S. after one was found on the north coast. They are asking the public for assistance by keeping an eye out for the Chinese Mitten crab and reporting any finds.

“A Chinese mitten crab, a prohibited species in Oregon, was caught on April 22 in the Lower Columbia River east of Tongue Point,” said Oregon Department of Fish and Wildlife (ODFW). “Chinese mitten crabs have not been confirmed in the Pacific Northwest until now. A single Japanese mitten crab was found in the same area in 1997. “

Although rare in Oregon, mitten crabs have a history of causing severe ecological and infrastructural damage, particularly in the San Francisco Bay area during the late 1990s when their population peaked. Accurate identification of this species is crucial, and any sightings should be promptly reported to your local ODFW office, along with the location where it was found.

Chinese mitten crabs possess distinct features that set them apart from native crab species. They have a small notch between their eyes and four spines on each side of their carapace. Their hairy, mitten-like claws, which give them their name, can vary in color from brownish-orange to greenish-brown. Since crab identification can be tricky, some native species are occasionally misidentified as invasive.

These crabs spend most of their lives in freshwater but require saltwater to reproduce. Newly hatched larvae develop in open saltwater areas such as bays and estuaries. As they mature, fully molted juveniles migrate upstream into brackish and freshwater zones a few miles inland.

The crab was initially caught by a commercial fisherman on the north Oregon coast who wisely brought the unusual specimen to ODFW's Columbia River staff. From there, the crab was identified as a Chinese mitten crab by an ODFW shellfish biologist.

This particular crab, a large male, may have been illegally introduced into the Columbia River by human activity or transported as larvae in ballast water.

ODFW urges anyone using the Columbia River to remain vigilant for mitten crabs. If you encounter one, take photographs (if possible), note the location, and report it to ODFW or the Oregon Invasive Species Council through their online portal.

“ODFW biologists are working with the Washington Department of Fish and Wildlife and NOAA to determine if other mitten crabs are in the Columbia River,” the agency said. “Methods include setting up trap lines and potentially collecting water and substrate samples to look for environmental genetic markers specific to the mitten crab.”

In the meantime, both Oregon and Washington have been dealing witht he consequences of the green crab, especially in Netarts Bay near Oceanside and Tillamook.

Green crab - courtesy Washington Department of Fish and Wildlife

These small yet aggressive invaders wreak havoc on ecosystems by preying on shellfish and uprooting eelgrass. Originally introduced to the West Coast via San Francisco Bay in the 1980s, green crabs have spread throughout estuaries and bays across California, Oregon, and Washington, recently reaching as far as Alaska. Their remarkable ability to tolerate diverse temperatures and salinity levels has made them a global ecological challenge.

Marina Dreeben, Stewardship Coordinator for the Netarts group WEBS, said there is an urgency to this critter's expansion in range.

“The presence of green crabs poses a significant threat to native shellfish and countless other species,” Dreeben said.

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Andre' GW Hagestedt is editor, owner and primary photographer / videographer of Oregon Coast Beach Connection, an online publication that sees over 1 million pageviews per month. He is also author of several books about the coast.

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