Editor’s Note: Whatcom Watch has entered a cooperative agreement with Salish Current. When possible, we will share each other’s content. Salish Current, an online-only news organization, covers the North Sound area and Whatcom Watch mainly covers Whatcom County issues. Visit https://salish-current.org.
by Margaret Baumgartner
European green crabs are among the most invasive marine species, preying on oysters, clams, juvenile fish and other crustaceans. They are resilient, adaptive and reproduce quickly. And they are impossible to remove entirely.
In Lummi, they threaten the environment, culture and finances.
The crabs were first detected in 2019 in the Lummi Bay Sea Pond. At that time, there were an estimated 40 crabs. By the next year, 2,500 crabs were caught by Lummi Natural Resources. By 2022, about 86,000 crabs were trapped.
Now the goal for Lummi Natural Resources is to reach a functional eradication of green crabs. The exact number of crabs in the bay is unknown.
“We will continue the pressure until they are hammered down to a state in which they are undetectable by the Lummi people,” said Shawn Evenson, aquatic invasive species division manager for Lummi Natural Resources. “We aren’t there yet, but we’re on our way.”
European green crabs will always be a problem for the Lummi people, according to Evenson. Once their population is controlled, Lummi Natural Resource will still have to trap and mitigate the crabs. Rather than the hundreds of traps they now use to catch them, the crabs would be monitored with early detection trapping, allowing Lummi Natural Resources to closely watch the crabs and deal with groups as they arise before they get the chance to take over again.
courtesy: LNR Aquatic Invasive Species Division
A Lummi Natural Resources employee displays a European green crab after taking it out of a trap.
Salmon, Dungeness Crabs at Risk
In Maine, European green crabs have been blamed for the collapse of the soft-shell clam industry, according to Chase Gunnell, the European green crab emergency public information officer for the Washington Department of Fish and Wildlife (WDFW).
“Now, European green crabs threaten Washington’s environment, coastal economies and tribal and cultural resources,” Gunnell said.
One green crab can eat up to 40 shellfish a day. That means the green crabs trapped in 2022 could’ve eaten 3.5 million oysters and clams every day while in the bay.
The food green crabs eat in large amounts is traditionally gathered by the Lummi people. This also causes undue hardship for the fishers and harvesters who rely on the animals being eaten by the green crab to make a living, according to Evenson.
Eelgrass beds are another point of concern. While searching for their next meal, European green crabs can destroy eelgrass beds that harbor other species such as salmon.
“If those eelgrass are gone, it’s just another cut of a thousand cuts that the salmon are experiencing,” Evenson said.
According to Evenson, as salmon populations have declined, Dungeness crabs have emerged as an important cultural and commercial seafood for the Lummi people. Unfortunately, European green crabs also impact juvenile Dungeness crabs.
If a Dungeness crab and a European green crab of the same size go head-to-head, according to Evenson, the green crab would win. But if the Dungeness crab is bigger, it would win. European green crabs can grow up to 4 inches long, whereas Dungeness crabs can reach lengths of 10 inches. Adult Dungeness crabs are not at risk, but their young are.
The typical range of European green crabs is from zero to about 14 feet deep. However, in areas where adult Dungeness crabs are, they typically don’t go deeper than 12 feet.
“There is a biotic fence that is helping us out,” Evenson said. “But, if the green crab were left to go unchecked, eventually they would have the biomass to push out even their fiercest competitors.”
Learning From the East Coast
In Lummi, European green crabs threaten tribal food supplies and their economy. In Washington state, shellfish and aquaculture industries, such as orcas, are at risk.
“Washington has invested tens of millions of dollars in estuary habitat restoration efforts to help recover salmon, orcas and other species,” Gunnell said. “European green crabs can literally undermine these efforts and have the potential to harm eelgrass, forage fish populations, salmon recovery and southern resident killer whales.”
In Washington state, European green crabs were first identified in 1998 on the coast in Willapa Bay and Grays Harbor. Due to a lack of resources and funding, complete management of the species was unable to occur then, according to Gunnell.
Now, their range is in multiple locations along the Washington coast, Lummi Bay and Sooke Basin. Smaller numbers of the infestation are in areas of the Strait of Juan de Fuca, San Juan Islands, Bellingham Bay and Padilla Bay.
Exact estimates of how many green crabs are here are difficult because of the marine environment. Rather, researchers look at how many were trapped. In 2023, more than 360,000 were trapped in Washington state, according to Gunnell.
Heavy trapping by WDFW, tribes such as Lummi, shellfish growers and other partners has helped to decrease the presence of the European green crab in the state.
Before they were on the West Coast, the European green crabs invaded the East Coast. Evenson said the situation on the East Coast helped raise the alarm when European green crabs started showing up in Washington.
“Look at the East Coast, look what they’ve done. We don’t have to speculate. We know what an uncontrolled European green crab population can do,” Evenson said. “It decimates the native species and erodes habitat.”
Don’t Kill It
If someone comes across what they believe is a European green crab, dead or alive, they should take a photo and report it, experts advise.
Several native species of crab in Washington state are green. This has led people to misidentify crabs as invasive European green crabs, Evenson said, and harm native species instead.
“The very same species that we’re trying to protect,” Evenson said, “when enthusiastic yet untrained people want to smash a green crab, nine times out of 10, [they] are smashing a native species.”
Send photos and note location of European green crabs found on the Lummi reservation to Lummi Natural Resources at 564-213-6666 or email the European green crab prospecting biologist at JonathanH@lummi-nsn.gov.
Elsewhere in Washington state, report European green crab sightings to WDFW or the Washington Invasive Species Council.
________________________________________
Margaret Baumgartner is a soon-to-be graduate of Western Washington University. She is obtaining her bachelor of science in environmental science and bachelor of arts in journalism.
