Invasive European Green Crabs have spread across the Washington coast at an exponential rate in recent years, prompting Gov. Jay Inslee to issue a state of emergency response in January 2022 to combat the infestation.
This type of crab is a globally damaging invasive species that poses a threat to native shellfish, eelgrass, and estuary habitat critical for salmon and many other species, according to the Washington Department of Fish and Wildlife (WDFW). First detected on the Washington coast in 1998, the rising Green Crab population is potentially linked to rising water temperatures, which are preferred conditions for Green Crabs.
Inslee’s order instructed WDFW to begin implementing emergency measures to prevent the crab’s permanent establishment and expansion in Washington.
The Washington State Legislature granted over $8 million to carry out emergency measures against the European Green Crab infestation in the 2022 Supplemental Operating Budget. Three boats, nearly a dozen new employees, and over 700 specialized traps have been put to use this spring as a result, according to WDFW.
As of July 10, over 106,000 European Green Crabs have been removed from Washington waters, the state reports.
European Green Crabs have been found in several locations along the Washington coastline, including Lummi Bay, Willapa Bay, Makah Bay and Hood Canal.
The invasive crab has not yet been found anywhere south of Admiralty Inlet or in Puget Sound proper — and experts hope to keep it that way, said WDFW European Green Crab Emergency Public Information Officer Chase Gunnell.
State fish and wildlife staff is working with the Lummi Nation, Makah Tribe, Shoalwater Bay Tribe, Willapa-Grays Harbor Oyster Growers Association, volunteers, and other partners to combat the spreading population of Green Crabs in Washington.
Invasive species can devastate local ecosystems, toppling food webs and potentially disrupting human resources and profits as well.
“They are voracious predators,” said Gunnell about Green Crabs. The crabs eat eelgrass, clams, oysters, and smaller native crabs.
Eelgrass is a vital part of ecosystems and supports countless animals, both large and small. These crabs eat the eelgrass, and also dig it up in their search for food. This affects all the other organisms that rely on the eelgrass ecosystem for food and shelter.
Because Washington is in the early stages of the infestation, experts do not know yet how severely Green Crabs could harm the state’s economy and ecosystems. They can, however, look at the species’ impact on the East Coast, which has been ongoing since their arrival on the coast in the 1800s.
The infestation along the East Coast has had “significant impacts on shellfish, soft shell crab, other aquaculture,” according to Gunnell. This is especially concerning for Washington residents since the state houses a much bigger shellfish industry than many East Coast states.
Stop the crabs
There are several steps people can take to help stop the spread of Green Crabs and other invasive species.
Invasive species don’t respect property lines, said Executive Coordinator of the Washington Invasive Species Council (WISC) Justin Bush. If left unchecked, he said , our neighbors’ problems will become our own.
“The number one thing is to be aware of what’s around you,” said Bush. “If you see something you’ve never seen around you, don’t be afraid to snap a picture and report it to WISC.”
At this time, WDFW advises residents not to kill crabs they suspect could be invasive because it is easy to misidentify native species as invasive without training. Instead, Bush encourages residents to photograph and report anything that looks out of the ordinary.
He said that although it may be a false alarm, reporting what you observe could lead to the first discovery of an invasive species in an area. Catching an invasive organism before it infests an area can make millions of dollars of difference. It can also stop the desolation of an ecosystem before it starts.
There are various volunteer programs to help identify and monitor Green Crabs in Washington. One of the most prominent is through the University of Washington’s Sea Grant organization. Volunteers who join the Crab Team “adopt” a stretch of shoreline or estuary to monitor and detect any Green Crabs in the area, reporting back their findings to WDFW. If any Green Crabs are detected in the area, volunteers will mobilize to find and eradicate the crabs before their population size is uncontrollable.
Crabs that are identified and removed from the wild are humanely frozen to kill them with as little discomfort as possible, according to WDFW. At this time, the dead crabs are disposed through composting. WDFW and its partners are currently looking into finding a more constructive use for the dead crabs, such as turning them into fertilizer.
Other invasive species
Aside from the European Green Crab, there are several other invasive species which are particularly harmful to Washington ecosystems, including various varieties of Knotweed as well as Quagga and Zebra mussels.
Quagga and Zebra Mussels are hitchhiker species, which means they can travel between bodies of water by hitching a ride in leftover water in leisure boats, fishing equipment, and even water sandals or boots.
Anything that has contact with water and is not carefully cleaned can transfer the invasive shellfish to new bodies of water.
There, they grow and crowd around anything they can latch onto, clogging up submerged pipes, boat propellers, and any other submerged object in their path.
The best way to combat the spread of these and other invasive waterborne species is to follow the simple “clean, drain, dry” protocol suggested by WISC.
First, WISC instructs to carefully clean equipment before transferring it between water sources. Next, drain any excess water out of boats or any container. Lastly, make sure to let equipment dry out completely before transferring it to another body of water.