Cases of mistaken crab identity underscore request to report and release suspected European green crabs
Reminder: photograph and report suspected invasive crabs at wdfw.wa.gov/greencrab, and return the crab where you find it.
The Washington Department of Fish and Wildlife (WDFW)’s Aquatic Invasive Species (AIS) unit recently received a report from a concerned member of the public who claimed to have collected nine invasive European green crabs from a Hood Canal beach.
Upon reviewing their photo, shown below, WDFW staff quickly determined these were in fact helmet crabs, a native species common in shallow marine waters.
Like Washington’s other native species of kelp, graceful, and shore crabs, helmet crabs are regulated as “Unclassified Marine Invertebrates” and are closed to all harvest or possession under state shellfish regulations.
While we appreciate their concern about invasive species, the reporting party was reminded to photograph and report suspected European green crabs using the form at wdfw.wa.gov/greencrab, leaving the crab in question where it was found.
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 Invasive Species, it is illegal to possess or transport live European green crab in Washington.
WDFW staff will review reports and respond quickly to confirmed green crab sightings. Training, permits, equipment, and other resources for European green crab control may be available for shellfish growers and others who own or manage shellfish beds, beaches, or tidelands. Please contact ais@dfw.wa.gov to learn more or to request materials.
Our partners with Washington Sea Grant also offer volunteer programs to assist with European green crab monitoring and early-detection surveys, including a new Molt Search effort with WSU Extension.
European green crabs are considered 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 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.
How to identify European green crabs
The most distinctive feature of the European green crab 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. This number of spines is different from any other crab you are likely to see in Washington.
Unfortunately, misidentified crab reports like the one mentioned earlier are common in Washington’s portion of the Salish Sea, where invasive European green crabs remain rare in most areas. WDFW has even received several reports of people illegally smashing and killing native crabs in Puget Sound after mistaking them for European green crabs.
Incidents like this are one significant reason why WDFW has not yet opened recreational harvest for European green crabs in Washington. Other reasons include restrictions on access to private tidelands and shellfish beds, and concerns about bycatch of protected fish and shellfish, especially if traps are exposed during low tide.
European green crabs (Carcinus maenas) 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. They are usually 1” to 4” wide across the shell and are not always green and may also be orange, red, brown, or yellow.
Crab identification guides and more information are available on our webpage, and are now posted at many Washington beaches, marinas, and water access areas with a QR code, 1–888-WDFW-AIS phone number, and ais@dfw.wa.gov email to report suspected European green crabs.
How green crabs got here
In 1989, European green crabs were first discovered on the West Coast in San Francisco Bay, California, likely transported from their native range in western Europe and north Africa in the ballast water of ships. They made it into Oregon, Washington, and British Columbia coastal estuaries in the late 1990s helped by strong El Niño currents.
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.
European green crab numbers remain low in the Strait of Juan de Fuca, San Juan Islands, and Bellingham and Padilla bays. They were first detected in Hood Canal in 2022.
As of early 2024, European green crabs have not been confirmed in Puget Sound south of northern Hood Canal and Marrowstone Island in Admiralty Inlet. Early-detection monitoring continues across central and south Puget Sound.
Trapping and monitoring efforts by WDFW AIS staff, tribes, shellfish growers, and many other state and federal agencies and partner organizations are ongoing and expected to ramp up again in April for the spring-fall field season. More than 330,000 of these invasive crabs were trapped and removed in 2023, most from the Washington Coast including Willapa Bay.
Learn more on WDFW’s European green crab online hub, or review reports and regular updates on our species webpage.
More information on aquatic invasive species in Washington is available on this webpage.
