Invasive green crab found in San Juan Island waters

by: Natasha Chen Updated:

SEATTLE - A team of researchers has found the first European green crab in the Puget Sound, a discovery which has heightened the level of urgency to find more of this invasive species before it spreads and causes harm to other marine life.

The European green crab arrived on the East Coast about 200 years ago and has already been blamed for the collapse of the Maine soft-shell clam industry.

The green crab arrived on the West Coast in the 80s and 90s. In Bodega Bay, California, its presence has caused a significant reduction in the population of clams and native shore crab.

While it has so far stayed away from the inland waters of Washington, the crab team of the University of Washington and Washington Sea Grant has been actively looking for it.

On August 30, one turned up in Westcott Bay. Now, there’s an expanded effort to trap more of them if they exist.
“Currently, we expect them to be most successful in these salt marsh or pocket estuary habitats. It is entirely possible that they could expand beyond those habitats to where they’d interact with our native clam species,” said Jeff Adams, a marine ecologist.

Adams said the green crab has a deleterious effect on forage fish, which are eaten by salmon. He said people on the East Coast have been trying to figure out the best way to eat green crabs, as one way of limiting their population.

The Washington Sea Grant crab team’s website explains that the green crab has an ability to significantly alter any ecosystem it invades, feeding on clams, oysters, mussels, marine worms and small crustaceans. Because they can also feed on juvenile crabs and shellfish, the Dungeness crab industry could eventually be affected.
On Monday, Adams set some traps in a salt water marsh on Vashon Island.

“We let these traps soak overnight, and then we come collect them the next day – again, hoping only to find native species,” Adams said. “Hopefully we won’t, and we’ll actually look at the native species.”

It is illegal to possess a European green crab, so Adams said anyone who finds one or comes across a molt should take a photo of it and send it to crabteam@uw.edu.

A green crab will be about three inches wide and have five points each on its right and left sides.

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