Invasive European green crabs found in Drayton Harbor

Species not found this year in JeffCo

Posted 10/16/19

After volunteers from the Washington Sea Grant Crab Team monitoring program discovered an invasive European green crab at Kala Point Lagoon last September, they kept their eyes peeled for the invasive crustaceans during their crab searches this year.

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Invasive European green crabs found in Drayton Harbor

Species not found this year in JeffCo

Posted

After volunteers from the Washington Sea Grant Crab Team monitoring program discovered an invasive European green crab at Kala Point Lagoon last September, they kept their eyes peeled for the invasive crustaceans during their crab searches this year.

“We did not find any European green crabs for the 2019 season in Kala Point Lagoon,” said Chris Jones, leader of the local crab team. “There were some found, I believe, in Kilisut harbor (between Marrowstone and Indian Islands) a while back.”

But even though they didn’t find any this year, doesn’t mean they aren’t out in the Puget Sound.

The invasive crabs are an issue because they destroy eelgrass habitat and eat native crabs, threatening native Dungeness and other species.

The green crab, native to the coasts of Europe, has been found on the outer coast of Washington since the 1990s, but did not appear in the Salish Sea until 2012, when green crabs were discovered on the Canadian side of the Strait of Juan de Fuca. The Washington Sea Grant has been monitoring the shores of the Salish Sea since then, searching for signs of invasion.

Last month, this team of crab searchers found evidence of European green crabs in Drayton Harbor during regular monitoring. They then trapped 17 green crabs during a two-day rapid response in late September, according to a press release from the Washington Sea Grant.

“Finding this many invasive green crabs so quickly in one area raises a serious concern that there may be an established and reproducing population in Drayton Harbor,” said Allen Pleus, WDFW’s aquatic invasive species manager. “We are working with our partners at Washington Sea Grant to do additional trapping in the area and will work with local governments, tribes, and other partners to plan an appropriate response.”

The green crab first appeared on the West Coast in the San Francisco Bay in 1989, according to the Washington Sea Grant website. It moved both south and north along the coast since then, and was sighted in Willapa Bay and Grays Harbor, as well as on the coast of Vancouver Island in 1998 and 1999.

The European green crab has not just invaded the West Coast, but has also invaded coasts in Australia, South Africa and South America, as well as causing large amounts of damage to the East Coast of the United States and Canada, from Newfoundland down to South Carolina.

The species was most likely introduced to non-native habitats by human actions. The crabs can travel in ballast water, which is water carried in below-decks tanks to improve ship stability. They can also sometimes be trapped among packaging that is used to ship live seafood. Once the crab escapes to the wild, it can spread easily during its larval stage of life. Green crab larvae can survive as plankton for up to 80 days, and are dispersed along the coast by ocean currents.

Since 2016, European green crabs have been found at 12 locations along Washington’s inland shoreline, according to the Washington Sea Grant. Trapping 17 green crabs at Drayton Harbor over just two days is significant because it is the highest number of crabs trapped in such a short window from one area of Washington’s inland shorelines.

Research teams like Port Townsend’s go out to areas like Kala Point to search for signs of an invasion. In specialized research traps, they catch anywhere from 500 to 1,000 crabs. If a European green crab is found in the mix of trapped crabs, the teams alert the Washington Sea Grant and researchers with the Washington Department of Fish and Wildlife step in to provide a deeper assessment of the area, with several days of intensive trapping.

Regular beach-goers can be on the lookout for the invasive species as well, but they’re not as easy to detect as their name implies.

What distinguishes the green crab from native species such as Dungeness crabs or hairy shore crabs is the five spines found on the outside of the eye on the crab’s shell. They don’t usually have a green color and can easily be confused with a hairy shore crab.

However, even if someone is certain they have found a green crab, they should not pick it up, because it is illegal to possess the crab in Washington State.

“This is a prohibited species in Washington,” said Emily Grason, who works with the Washington Sea Grant. “If someone thinks they found one they have to leave it where it is. Then, they can email a photo or a couple photos to us and give detailed information about the location where they found it.”

For more information about European green crabs, and what to do if you find one, visit wsg.washington.edu/crabteam.

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