Green Crab Community Science Opportunity

Calling all community scientists, volunteers, shoreline landowners, and beachgoers!


The European green crab is a hardy and voracious predator native to Western Europe and Northwestern Africa. This species has invaded intertidal zones around the globe and, according to the Washington Department of Fish and Wildlife, it is considered one of the world’s worst invasive species. 

European green crab were first detected in the Washington area of the Salish Sea in 2016 – they were found in at Westcott Bay on San Juan Island and in Padilla Bay.  Since 2018, the crab has been found in an increasing number of places and in 2021, European green crab numbers expanded dramatically in the Lummi Nation’s Sea Pond, and in outer coastal areas such as Grays Harbor, Makah Bay, and Willapa Bay.   

This invasive crab threatens shellfish, and juvenile Dungeness crab, eelgrass beds which provide critical habitat for juvenile salmon, the food supply for shorebirds, and the overall health of Washington’s marine waters.

WDFW, Washington Sea Grant, tribal co-managers, and partners (a coalition known as The Crab Team) currently monitor and trap European green crab at about 60 sites. Still, these only cover a small fraction of the suitable nearshore habitat for this animal.  The detection of European green crab molts could be an early indicator of the presence of European green crab in the area.  If citizen scientists, volunteers, shoreline landowners, and beachgoers knew what to look for, they could provide valuable information that would help to guide future Crab Team monitoring and trapping efforts. 

WSU Extension is collaborating with WA Sea Grant on a training workshop to teach volunteers how to conduct a systematic 20-minute survey for crab molts, how to properly identify the European green crab, how to take measurements of the invasive crabs as well as Dungeness crabs and how to report their findings using a mobile app.  

Community Science Opportunity

Friends of the San Juans is coordinating the Green Crab Molt Surveys for San Juan County and will hold a volunteer training workshop at the San Juan Island Grange on May 19th from 11:30 am to 1:30 pm, followed by a field training (BioBlitz!) at Jacksons Beach from 2:00 pm to 4:00 pm.

Click to Register via Eventbrite!

 For more information and to register for the workshop, email [email protected].

We believe that our property is more valuable if we and our neighbors protect the shoreline. Orcas need salmon. Salmon need forage fish. Salmon and forage fish need the protection of eelgrass and kelp. Eelgrass and kelp need clean water. Shoreline protections are good for ecosystems and for the long-term economy of these lovely islands.

Val and Leslie Veirs

members, San Juan Island