Do You Know Where Your Green Crabs Are Sleeping?

You’ve heard me mention my involvement in citizen science and the various organizations I’ve worked with. It adds a another layer of enjoyment when I’m outdoors to be actively involved in collecting data that will be used for finding solutions to some of the environmental issues facing our planet. I recently came across another worthwhile project that I attend to participate in; The Crab Team.

This project’s mission is to detect the invasive European green crab at the earliest possible stage of invasion to increase the ability to control population and reduce green crab impacts and build a long-term dataset n green crab and other mobile organisms living in soft sediment habitats around Washington.

The crab is an effective predator, adept at opening bivalve shells. In California, it has caused losses as great as 50% in Manila clam stocks.

European Green Crab

The European green crab (Carcinus maenas) is a small shore crab whose native distribution is in the northeast Atlantic Ocean and Baltic Sea. The crab is an effective predator, adept at opening bivalve shells. In California, it has caused losses as great as 50% in Manila clam stocks. It preys on numerous other organisms, making these crabs potential competitors for the food sources of native fish and bird species.

This small shore crab has the potential to significantly alter any ecosystem it invades. It has been blamed for the collapse of the soft-shell clam industry in Maine. The green crab feeds on many organisms, including clams, oysters, mussels, marine worms, and small crustaceans. Because it can also prey on juvenile crabs and shellfish, a northward spread to the Washington coast and Puget Sound could put our Dungeness crab, clam, and oyster fisheries at risk, and the green crab might compete with native fish and bird species for food.

First seen in San Francisco Bay in 1989, the green crab moved southward to Monterey Bay and northward to Humboldt Bay, California, Coos Bay, Oregon, and many other Oregon estuaries. Green crab were sighted in Willapa Bay and Grays Harbor, Washington, and on the west coast of Vancouver Island in 1998 and 1999. Because of the risk posed by this species, green crab were closely monitored in Washington; populations appeared to decline after the initial introduction on the coast, and they were never observed in Puget Sound or the Strait of Juan de Fuca. However, they were very successful on Vancouver Island, particularly in Barkley Sound, and their recent expansion into Sooke Inlet brings them even closer to Washington’s inland shorelines.

Now green crabs are close enough that they could drift into Puget Sound as larvae. Green crab populations tend to thrive when waters are warm, such as strong El Niño years. As 2015-2016 is predicted to be a very strong El Niño year, it is possible we will see the green crab in new places.

The Crab Team

The Crab Team project was launched in 2015, in response to a Washington Department of Fish & Wildlife (WDFW) mandate to monitor for European green crabs along inland Washington shorelines. By using citizen science they have greatly increased their reach in monitoring for this invasive specifies.

You can participate by learning how to identify the European Green Crab and reporting any sightings to or you can take a more active role and attend a training workshop that are held during the winter.

If you do find a green crab take photos of it from several angles to attach to your email. Add something in the photo that can be used as scale for determining the size. Note the time and place where the sighting occurred. Then leave the crab there! It is illegal to possess a green crab in the State of Washington without a special permit, so leave any crabs you find behind.

Hope to see you in a workshop this winter!


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