Scientists begin European green crab trapping season in Drayton Harbor

Scientists are setting traps for the invasive European green crab around Drayton Harbor in hopes of catching more juvenile crabs that were discovered last fall.

About 30 crabs have already been found in Drayton Harbor since the 2025 trapping season began March 31, said Allie Simpson, ecosystem project coordinator at the Northwest Straits Commission.

“A lot of the crabs that we are finding seem to be last year’s juvenile cohort, so we’re cleaning up what we weren’t able to get last year,” Simpson said.

Scientists saw the juvenile crabs in Drayton Harbor starting in late summer until the trapping season concluded in the fall. The juvenile crabs were from larvae that survived the warm El Niño winter of 2023-24, which created more survivable conditions for the larvae, which was observed in both Whatcom and Skagit counties.

“That was very clearly a regional trend,” said Emily Grason, marine ecologist and crab team program lead at Washington Sea Grant.

Washington scientists broke records by capturing over 1 million crabs along the state’s shorelines in 2024, though the number also correlates with more traps being set, according to Washington Sea Grant.

Scientists trapped 535 green crabs in Drayton Harbor in 2024, making it the highest number of crabs trapped in the area on record. Nearly 85 percent of those crabs were juveniles, Simpson said.

Last year, about 17 crabs were caught for every 100 traps set, Grason said. The next highest catch rate was in 2022, when 11 crabs were caught per 100 traps.

Scientists now hope that fewer crabs will be found during the 2025 trapping season, as a La Niña weather pattern created a colder winter this year that may kill larvae.

Washington scientists, who were already working to eradicate the crab around the state, found the crab in Drayton Harbor in August 2019. Considered one of the world’s worst invasive species, the crabs have devastating impacts on native ecosystems including Dungeness crab, oyster, clam and seagrass populations.

“It’s not really discussed any longer that the goal is 100 percent eradication of green crabs, but it’s still a worthwhile endeavor to try to keep populations as small as possible,” Grason said.

While the population is the largest it’s ever been in Drayton Harbor, Grason said the harbor still has a relatively low population compared to other areas where trapping is occuring in Washington.

“We’re concerned about it because the number is still growing and that’s not a good sign, but it’s also much smaller than it could be if we weren’t doing any trapping,” Grason said.

Washington Sea Grant, Northwest Straits Commission and Washington State Department of Fish and Wildlife (WDFW) are leading efforts to keep the crab’s population at a manageable amount in Blaine.

Drayton Harbor Oyster Company co-owner Steve Seymour said his staff, who work on the company’s oyster farm in the harbor, occasionally see green crabs but haven’t observed them impacting the shellfish.

“We’ll occasionally see one out there but they’re not out in huge numbers,” Seymour said.

Scientists have been focusing their trapping efforts over the past few years around pillars at the old Cherry street pier and at the mouths of both the Dakota and California creeks. In 2024, the most crabs were found at the mouth of California Creek, with 160 captured, most of which were juveniles.

WDFW has also found crabs in the mouth of Terrell Creek in Birch Bay, Simpson said.

Simpson said scientists occasionally trap outside of the core sites to get a better idea where else the crabs could be located, and found a sizable population in Dakota Creek under I-5 in 2024.

This year, Simpson said the scientists want to do more trapping in the creeks to ensure they don’t become a hotspot. She said scientists are looking for property owners with land adjacent to creeks near Drayton Harbor to allow them to trap on their property. Those interested can contact Simpson at simpson@nwstraits.org.

The Washington State University Extension and Washington Sea Grant will hold training sessions for the public to learn how to search for European green crab molts, which can be an early indicator of the crab.

WSU Extension will hold the first training from 10 a.m. to noon Saturday, May 10 at the bp Heron Center in Birch Bay State Park. Three other trainings are scheduled in Snohomish and San Juan counties in June.

To register for the Whatcom County training, visit bit.ly/4jKyouW. For more information on the Molt Search program, visit bit.ly/42Y4DkS.

Anyone who sees what they believe to be a European green crab is encouraged to take a photo and share it with Washington Sea Grant or WDFW, Grason said. Both live and dead crabs should not be moved, but the molts can be kept for further verification. And while the crabs are not toxic to eat, they are illegal to possess in Washington state without a special permit.

“We were able to be in this area and start trapping efforts right as this invasion started, which has been a huge boost to our work and keeping Drayton Harbor the beautiful ecological area that it is,” Simpson said. “If we let it get out of hand, if we aren’t trapping, if we aren’t able to access the areas we need to, then it will potentially become a pretty concerning site.”