European green crab (Carcinus maenas)

WDFW staffer holding two European green crab
WDFW staffer holding two European green crabs.
Two European green crabs removed by WDFW from Hood Canal near Seabeck in Kitsap County
Two European green crabs removed by WDFW from Hood Canal near Seabeck in Kitsap County. Photo WDFW.jpg

AIS Aquatic invasive species

Classification: Prohibited
Invasive species family: Portunidae
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Category: Crustaceans
Family: Portunidae
Ecosystems: Marine shorelines
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If you find a suspected European green crab or its shell in Washington, report it as soon as possible using the form on this webpage. Download the Crab Identification Guide and take pictures to confirm identification. At this time, we are not asking the public to kill suspected green crabs. This may sound counterintuitive but is intended to protect native crabs from cases of mistaken identity. As a Prohibited species, it is illegal to possess a live European green crab in Washington.

This webpage includes detailed information and resources for invasive species practitioners and other partners. For information for the public on identifying and reporting European green crabs, please visit this page.

Sign up for our European Green Crab Management Updates email list.


For previous updates click the Conservation tab below or see our June 2022 news release:
Emergency measures deployed to control invasive European green crabs in Washington waters.

An increasing threat

The European green crab (Carcinus maenas) is a globally damaging invasive species that poses a threat to native shellfish, eelgrass, and estuary habitat critical for salmon and many other species.

Potential impacts include destruction of eelgrass beds and estuarine marsh habitats, threats to the harvest of wild shellfish and the shellfish aquaculture industry, salmon and forage fish recovery, and a complex array of ecological impacts to food webs. Research is ongoing regarding potential impacts on juvenile Dungeness crab and crab fisheries

In areas where European green crabs have been able to establish large populations for extended periods of time, they have had dramatic impacts on other species, particularly smaller shore crabs, clams, and small oysters. While green crabs cannot crack the shell of a mature oyster, they can prey upon young oysters, and will dig down six inches to find clams to eat. One green crab can consume 40 half-inch clams a day, as well as other crabs its own size. Their digging can have significant negative impacts on eelgrass, estuary and marsh habitats.

Learn more in this short video about European green crab impacts in New England on the Massachusetts coast. The below Northwest Now video segment from August 2022 covers European green crab concerns and management in Washington state. 

    Description and Range

    Physical description

    European green crab identification graphic, 2022
    Counting the five spines or "marginal teeth" on each side of a European green crab shell is the best method for identification.

    European green crabs are shore crabs and are found in shallow areas—typically less than 25 feet of water—including estuaries, mudflats, intertidal zones, and beaches. They are not likely to be caught by recreational shrimpers or crabbers operating in deeper water, but may be encountered by beachgoers, waders, clam and oyster harvesters, or those crabbing off docks or piers in shallow areas.

    The most distinctive feature is not its color – which can vary from reddish to a dark mottled green – but the five spines or teeth on each side of the shell. There are three rounded lobes between the eyes; and the last pair of legs are somewhat flattened. The carapace is broader than it is long and seldom exceeds 4 inches across.

    In Washington state, the European green crab is most often confused with the native hairy shore crab or helmet crab.

    Download a crab identification guide from Washington Sea Grant or learn more about green crab ecology in this handout.

    Or download this WDFW flier with European green crab reporting information and photos of native crab species. 

    Geographic range

    The European green crab first became established the United States in the mid 1800s, arriving by ship to the Cape Cod region. In the early 1900s they spread northwards, where they are believed to have contributed to the dramatic declines in the soft shell clam fishery as far north as Nova Scotia. In 1989, green crabs were first discovered on the West Coast in San Francisco Bay, California and made it into Oregon, Washington, and British Columbia coastal estuaries in the late 1990s helped by strong El Niño currents. They were detected in southeast Alaska in 2022.

    European green crabs were discovered on the Washington coast in 1998 in Willapa Bay and Grays Harbor, and later in Makah Bay. European green crabs were first documented in the Salish Sea at Sooke Basin, British Columbia in 2012, and in the San Juan Islands in 2016.

    Beginning around 2018, state and federal agencies, tribes, and partners began to detect significant increases in European green crabs—potentially linked to warmer water conditions, especially in 2021—in areas including Willapa Bay, Grays Harbor, Makah Bay, and Lummi Bay.

    Current range

    While infestations are present at locations along the Washington Coast as well as in Lummi Bay in Whatcom County and Sooke Basin on southern Vancouver Island in British Columbia, European green crab numbers remain low across other areas of the Strait of Juan de Fuca, San Juan Islands, and Bellingham and Padilla bays. They were first detected in Hood Canal in 2022.

    European green crabs have not been confirmed in the Salish Sea south of northern Hood Canal and Marrowstone Island in Admiralty Inlet. Early-detection monitoring continues across central and south Puget Sound.

    Regulations

    Rules and seasons

    At this time, we are not asking the public to kill suspected green crabs. This may sound counterintuitive but is intended to protect native crabs from cases of mistaken identity. 

    The European green crab is classified as a Prohibited Level 1 Invasive Species in Washington, meaning they may not be possessed, introduced on or into a water body or property, or trafficked (transported, bought or sold), without department authorization, a permit, or as otherwise provided by rule. These regulations may change in the future, but for now they are the law.

    Though considered edible and fished commercially in parts of their native range, European green crabs aren’t any bigger than your fist and don't make the most appealing meal. Where eaten, they are used primarily for crab stock and soup.

    Bucket of EGC, Washington coast Willapa Bay. Photo by WDFW
    A bucket of green crabs trapped by WDFW staff.

    If you find a suspected European green crab or its shell in Washington, report it as soon as possible. You can also report sightings through the Washington Invasive Species Council app or Invasive Animal Reporting Form. 

    Download Washington Sea Grant's Crab Identification Guide and take several pictures from different angles to confirm identification. It’s also helpful to include a coin or other object to help show its size.

    Permits and management support may be available for shellfish growers or private tideland owners encountering European green crabs. Please contact ais@dfw.wa.gov. 

    Beachgoers, anglers, recreational crabbers, and others are asked not to tamper with European green crab traps, which are often deployed in shallow areas exposed at low tide and are typically identified with a bright orange buoy and an official tag or permit.

    Conservation

    WDFW European green crab updates

    Emergency measures deployed to control invasive European green crabs

    In 2021, WDFW, tribal co-managers, and partners identified an exponential increase of invasive European green crabs (EGC) within the Lummi Nation’s Sea Pond and outer coast areas, including Makah Bay, Grays Harbor, and Willapa Bay. This poses an imminent threat to Washington’s economic, environmental, and cultural resources. The $2.3 million appropriated by the State Legislature for EGC management in the 2021-23 biennium was not sufficient to control these exploding populations.

    On Dec. 14, 2021, Director Susewind submitted an emergency measures request for invasive green crab response to Governor Jay Inslee. While emergency funding was not immediately available, on Jan. 19, 2022, Gov. Inslee issued an emergency order to address the exponential increase in the European green crab population within the Lummi Nation’s Sea Pond and outer coast areas. The proclamation directs WDFW to begin implementation of emergency measures and urges the Legislature to provide additional emergency funding as requested by the WDFW as soon as possible.

    Working with the Governor’s office, the Office of Financial Management, tribal co-managers including the Lummi Nation, Makah Tribe, and others, and Washington Sea Grant, WDFW requested $8,568,00 million from the State Legislature during the 2022 supplemental session to control increasing European green crab populations. The Legislature fully-funded this request in the 2022 Supplemental Budget, which was signed by Governor Inslee on March 31. 

    The Washington State Emergency Management Division assigned European green crab response as a formal mission # 22-1085 on April 18. After meeting with other state and federal agencies, the Washington Department of Fish and Wildlife (WDFW) Director Kelly Susewind formally implemented an Incident Command System (ICS) on May 5 in delegating authority to Allen Pleus, WDFW’s Aquatic Invasive Species Policy Coordinator, to serve as Incident Commander. The ICS also identifies Coastal and Salish Sea management branches.

    With the emergency order and funding, WDFW has been working with tribes, other state and federal agencies, as well as shellfish growers and private tidelands owners to establish a coordinated response, hire and deploy personnel, and purchase and distribute equipment to areas with known green crab infestations. Three boats, nearly a dozen new employees, and more than 700 specialized traps have been deployed, with more on the way.

    For more information, see our June 2022 news release: Emergency measures deployed to control invasive European green crabs in Washington waters. 

      Limiting the invasion

      The Washington Department of Fish and Wildlife (WDFW) has focused much of its efforts in the early detection of green crabs by monitoring locations that offer good habitat for the species. If the species is detected at a new location, WDFW conducts rapid response actions to reduce or eliminate those new populations, and to prevent the spread of European green crab from established locations. 

      Learn how a broad collaboration of volunteers, agencies, and tribes is working together to keep the crabs at bay in Washington State in this interactive story map.

      Shellfish Transfer Permits

      Washington State prohibits the release of non-native species into Washington’s waters and the intentional import of live green crabs. To reduce risk of unintentional introductions, WDFW restricts movement of shellfish from green crab areas and requires that anyone seeking to move live shellfish into or around state waters be approved for an import or transfer permit, which may include precautionary treatment measures to further reduce risk.

      Resources

      A European Green Crab Management Updates email list is also available for sign up at wdfw.wa.gov/about/lists.

      Outreach and identification materials

      Washington Sea Grant Crab Team

      WDFW has teamed up with the Washington Sea Grant “Crab Team” who is leading a volunteer-based early detection and monitoring program for green crab. The Crab Team is also working to improve the understanding of native salt marsh and pocket estuary organisms and how they could be affected by green crabs. To learn more about early detection, monitoring, and volunteer opportunities, please visit the Sea Grant’s Crab Team website.

      Washington Sea Grant also has additional European green crab identification resources available on this webpage.

      EGC hiding in commercial oyster grower bags, Washington coast. Photo by WDFW
      Green crab hiding among commercial oyster grower bags.

      Salish Sea Transboundary Action Plan

      As the prevention of green crab infestations requires widespread help, WDFW worked with the Canadian Department of Fisheries and Oceans, the Puget Sound Partnership, and Washington Sea Grant to develop the Salish Sea Transboundary Action Plan.

      For more information on European green crab management in British Columbia, see this webpage from the Invasive Species Council of B.C., or watch this new video from Coastal Restoration Society about green crabs on Vancouver Island. 

      Presentations, videos and webinar recordings

      View our European Green Crab playlist on YouTube for all recordings.

      Environmental Education resources and curriculum

      2023 communications highlights

      2022 communications highlights

      2021 updates

      2020 updates

      2019 efforts and updates

      Please contact ais@dfw.wa.gov for information on European green crab control and monitoring work during earlier years. Or check out this 2016 video from Earthfix Media and Washington Sea Grant: Green Crab Invasion Hits Puget Sound