Crab that can climb 13-foot-high walls found in Pacific Northwest for 1st time

Yahoo

29-04-2025

A highly invasive species of crab — capable of climbing over 13-foot-high concrete structures — has been spotted in the Pacific Northwest for the first time, wildlife officials said.
A commercial fisherman caught what officials identified as a Chinese mitten crab last week in the Lower Columbia River, just south of the Washington state border, according to the Oregon Department of Fish and Wildlife, which released a photo of the crab.
"Chinese mitten crabs have not been confirmed in the Pacific Northwest until now," the department said in a news release Thursday.
Officials warned that the species wreaked havoc on the San Francisco Bay three decades ago.
"While this is a rare event in Oregon, mitten crabs caused significant infrastructure and ecological damage in and around San Francisco Bay when the population was at its height in the late 1990s," the department said.
Officials said the crab was a large male that could have been introduced illegally into the river by a person or by ballast water from a ship.
What are Chinese mitten crabs?
Chinese mitten crabs are an invasive species that are originally from East Asia. The Smithsonian says that the crabs first established an invasive population in the San Francisco Bay in the '80s — but they spread to the East Coast and have recently been spotted in New York.
The crabs, which are named for hairy, mitten-like claws, vary in color from brownish-orange to greenish-brown. Unlike any native crab species, they have four spines on each side as well as a notch between their eyes.
The crabs are capable of climbing over concrete structures at least 13 feet tall, according to the U.S. Bureau of Reclamation.
"Mitten crabs can also pass through lock systems and possibly climb fish ladders, or leave the water and walk around barriers where the terrain is suitable," the bureau says.
The creatures have been known to steal fishing bait and damage fishing gear, block power plant cooling systems and even amplify flooding risk by burrowing in banks, causing them to become unstable and erode.
Chinese mitten crabs spend most of their lives in freshwater, but adults can only reproduce in saltwater, according to the Oregon Department of Fish and Wildlife.
"Newly hatched larvae are in open saltwater in bays and estuaries and fully molted juveniles are found in brackish and freshwater areas within a few miles upstream of saltwater," the department says.
What's next
Oregon wildlife biologists are working with the Washington Department of Fish and Wildlife and NOAA to determine if other mitten crabs are in the area. Officials said they will set up trap lines and collect water and samples "to look for environmental genetic markers specific to the mitten crab."
In the meantime, officials are urging the public to keep an eye out for the furry creatures and report any sighting to the Oregon Department of Fish and Wildlife or the Oregon Invasive Species Council.
"It is important to correctly identify this species and report it to your local ODFW office with the location found," the Oregon Department of Fish and Wildlife said.
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