Invasive Crab Found For First Time In Washington’s Inland Saltwaters

A San Juan Islands beach survey turned up an “unexpected and unwelcome” discovery earlier this week: a raving mad crab.

It’s the first European green crab found in Puget Sound.

The invasive species whose scientific name Carcinus maenas translates to raving mad crab has “wreaked havoc” elsewhere in the world, according to Washington Sea Grant.

EUROPEAN GREEN CRAB. (WASHINGTON SEA GRANT)

EUROPEAN GREEN CRAB. (WASHINGTON SEA GRANT)

Their arrival in Maine is pinned on “dramatically” lower clam harvests and damage to kelp beds from their digging, and officials are concerned about what sort of impact they’ll have on shellfish and habitat here.

The crabs had been limited to coastal bays on the West Coast since turning up in 1989, but the worry is that there are an estimated 400 “potentially suitable sites” for them to take up residence in Washington’s inland saltwaters — Puget Sound, the San Juans, Hood Canal and the Strait of Juan de Fuca.

“We’re in the steps now to figure out what to do next,” says WSG marine ecologist Jeff Adams.

According to a joint press release from his agency, the University of Washington and WDFW, this one was found in Westcott Bay, which is just to the south of Roche Harbor on San Juan Island, by citizen science volunteers specifically looking for them. It was confirmed by two different experts.

VOLUNTEERS HELPED FIND THE "UNWELCOME" INVASIVE SPECIES. (WSG)

VOLUNTEERS HELPED FIND THE “UNWELCOME” INVASIVE SPECIES. (WSG)

Alarm bells began ringing here in 2012 when one was found in Sooke, on the Vancouver Island side of the Straits, and this year marks the first full season of searching by WSG’s Crab Team.

“We knew they were close and that’s why this was set up,” Adams says.

The crabs arrived in the US as far back as two centuries ago in ships from the Old Country. There are also infestations in Africa and Australia.

“We’re hopeful that by detecting populations early, we can control and prevent their spread,” Adams says.

Indeed, this does not mean we’ll have another species to crab for in Puget Sound. Despite their reputation, they’re not very big at all.

“There’s no meat. They’re not an eating crab,” says Mary Ann Wagner, also with Sea Grant, which describes them thusly:

Don’t let the name fool you; the “green” crab’s carapace color can vary widely. Several native Northwest crabs are also green. Adult green crab are about 3” across at the largest part of their shell, making them smaller than adult Dungeness and rock crabs, and the shell shape is triangular. The European green crab is the only crab likely to be found with five spines on the back shell from each eye to the widest point; native crabs either have more or fewer spines. Check out Identifying Green Crabs on the Crab Team website for more details on how to recognize this species.

 

EUROPEAN GREEN CRAB COLLECTED IN WESTCOTT BAY. (WSG)

EUROPEAN GREEN CRAB COLLECTED IN WESTCOTT BAY. (WSG)

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