The European green crab now spans the North Olympic Peninsula, having been found among fallen trees in the Tsoo-Yess River in Neah Bay, in the muddy canals of Graveyard Spit in Dungeness and in the waters of Kala Point near Port Townsend.
Its reach concerns resource managers because scientists list the crab as one of the world’s most invasive species and blame it for damaging the U.S. East Coast’s clamming industry.
The green crab, distinctive for its five spines on the side of each eye, competes with such native species as Dungeness crab.
Crab Team program manager Emily Grason, a marine ecologist with Washington Sea Grant, said it’s “important to do as much as we can now to avoid allowing populations to increase dramatically.
“Small numbers are where we can have the biggest impact in terms of management,” she said.
That’s why she finds trapping in Neah Bay critical for current and future management.
“We rarely get an opportunity like this one, and the one at Dungeness Spit, to attempt to intervene when an invasive species is still relatively rare,” Grason said.
“Because there have been very few situations like these, we don’t know for sure whether or not we will be able to completely eradicate green crab from these sites.”
One by one
Jefferson County residents found their first green crab on Sept. 8. Volunteers with Washington Sea Grant’s Crab Team spotted a 77-millimeter male green crab at Kala Point Lagoon during routine monthly trap sampling, which began in 2015.
The state Department of Fish and Wildlife staff followed with rapid response trapping and found another male (63 mm) green crab in Scow Bay between Indian and Marrowstone Islands.
Locations where volunteers look for green crab are part of the Sea Grant’s 54 early detection sites, including Indian Island County Park.
At the park a team of five members, including Andrea Carlson and Amy Does of Nordland, have helped trap once a month since 2016.
“We live here and want to do something to help,” Carlson said. “It’s the idea of citizen scientists. We did go through a lot of training and it’s people from all walks of life.”
At Indian Island County Park, Carlson and Does said they sort the crabs, such as hairy shore crabs, by sex and measure 10 randomly selected males and females for record-keeping purposes.
Grason said team members trap in the same locations and at consistent times to try and capture green crab at multiple points of their life cycles because when the season starts, some crabs may not be large enough to be retained by the traps or even be hungry when the traps go out.
“The bonus with volunteers is we can do more sites,” Grason said. “With 54 sites, doing that once per month would be a lot for staff. That’s 300-plus samplings per season.”
Chelsey Buffington, scientific technician for the state’s Department of Fish & Wildlife, said she’s worked closely with Neil Harrington, environmental biologist for the Jamestown S’Klallam Tribe, to trap new locations in Jefferson County — including Brinnon, Discovery Bay and Mystery Bay State Park — but did not find any other green crabs.
Staff and volunteers with the Washington Maritime National Wildlife Refuge in Dungeness have been trapping for the crab since 2001 but it wasn’t until 2017 when the first crab found on the Peninsula was discovered at Graveyard Spit.
Last year, resource managers caught 96 green crabs on the Spit. As of Sept. 24 of this year, staff and 27 volunteers caught 69 green crabs over 83 days using 2,620 trap placements.
Lorenz Sollmann, deputy project leader at the refuge, said the team will end trapping sometime this month, depending on tides, and begin again in April.
Crab Team volunteers discovered one green crab on June 15 at Dungeness Landing, across from the Dungeness Spit, after two years of routine trapping.
Jamestown S’Klallam Tribe and Fish & Wildlife Aquatic Invasive Species staff followed up with rapid response trapping but did not find more green crabs.
Harrington reported he trapped one green crab in the Jimmycomelately Creek estuary in 2017. This year he periodically set traps during the season in Jimmycomelately Creek and Washington Harbor but he didn’t find any crabs.
Green crabs weren’t on the radar of the Makah Tribe until this time last year.
A passer-by discovered a green crab in August 2017 near the Wa’atch River and reported it to Washington Sea Grant, which reached out to the tribe, leading them to coordinated, intense trapping efforts last October to catch 34 of the invasive species.
With a full season behind them this year, and a contingent of 28 volunteers plus tribal staff and multiple partner agencies, 1,030 green crabs have been captured as of Sept. 28.
“I feel like we did a lot of work, and it was productive with a lot of people behind it,” said Adrianne Akmajian, marine ecologist with Makah Fisheries Management.
She said their situation could be much worse if the visitor didn’t know how to identify and report the green crab.
Neah Bay’s green crabs range from 12 to 90 millimeters and were captured after 2,000 trap deployments in the Wa’atch River, Tsoo-Yess River and Neah Bay near shore.
Akmajian initiated trapping on the Wa’atch River after finding molts there and it remains a successful spot for trapping.
Makah Tribal staffers work with Sea Grant staff to find optimum locations to place traps.
In the Tsoo-Yess River, Akmajian said green crab like steep, muddy banks, and that staff and volunteers began placing traps by fallen trees that the crabs seem to like.
“I wish we had known that sooner,” she said. “I would have been trapping there then.”
At the rivers, they’ve used a number of different traps, and Akmajian said she wants to explore new baiting techniques to traps to see if the crabs would be enticed.
With an abundance of European green crab — at least for the North Olympic Peninsula — Akmajian was able to secure enough funding to continue trapping at the same level, starting next April.
“We’re going to have plenty of work to do next year,” she said.
Neah Bay-area trapping ended on Sept. 28 but Akmajian said she may do some exploratory trapping in the winter to see if the crabs remain.
Resources managers say the summer months remain an ideal time to trap; in winter months, green crabs typically go to deeper water because of tidal shifts, cooling temperatures and behavioral reasons.
With another full season of trapping ahead, Akmajian said she can hopefully determine a long-term strategy for management.
Akmajian has done numerous efforts to spread awareness through newsletters, signage and word-of-mouth, too.
As green crab continue to surface across the Peninsula, “we’re hoping not to be seeing a creeping base line going more inland to sites in Puget Sound,” Grason said.
“We hope we can intervene enough to have a durable change,” she said.
Across the Salish Sea including the North Olympic Peninsula, volunteers have found a few green crabs in June including one on Whidbey Island’s Lagoon Point, two at Westcott Bay and a molt in Fidalgo Bay on San Juan Island.
In a Crab Team blog, Grason said seeing green crab at new sites is concerning and that due to their size at sites like Dungeness Spit they’ve been there more than a year and avoided previous traps.
“This underscores a challenge of green crab management: sustained effort at a site is critical not only to detecting green crab in the first place, but also to long-term management success,” she said.
Grason said areas like Neah Bay and Dungeness Spit have capture rates per trap lower than “established” sites like Sooke, B.C., and the Sooke Basin where it has capture rates 100 times higher than Neah Bay.
But, she said “this gives us a better opportunity for control now than we would ever have if we did nothing and let them become abundant.”
Akmajian said that with another full year of trapping some of the researchers’ questions about the green crab population can be answered, such as if they can breed in the rivers.
Grason previously reported that genomics testing — mapping of genomes — at Woods Hole Oceanographic Institution in Massachusetts revealed the Dungeness’ crabs likely came from a coastal population in Washington state, Canada, Oregon or even California.
One of the 12 genetic samples taken so far from Neah Bay was found to be similar to crabs from Sooke Basin.
Resource managers say female green crabs can release hundreds of thousands of larvae per brood at least once a year. Some larvae can travel as far as 62 miles.
How to help
Researchers encourage residents who spot a European green crab to snap pictures of the crab(s) and send them to the Crab Team at email@example.com for identification. Resource managers ask the crabs be left alone. Limited volunteer opportunities are available for monitoring from April through Sept. with training in March.
Matthew Nash is a reporter with the Olympic Peninsula News Group, which is composed of Sound Publishing newspapers Peninsula Daily News, Sequim Gazette and Forks Forum. Reach him at firstname.lastname@example.org.