Green Crab community science opportunity

Submitted by Friends of the San Juans.

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.

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

European green crabs were first detected in the Washington area of the Salish Sea— found in Westcott Bay on San Juan Island and in Padilla Bay. Since 2018, they have been found in an increasing number of places. 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.

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, but these only cover a small fraction of the suitable nearshore habitat for this animal. The detection of European green crab molts could serve as an early indicator of the presence of European green crab in the area. If community 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.

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 11:30-1:30 pm, followed by a field training (BioBlitz!) at Jacksons Beach from 2 pm-4 pm.

Register for the upcoming workshop on Eventbrite:

For more information email Jess Newley, Community Science and Education Director at Friends of the San Juans,