Three Reserves Beat Back Green Crab Threat

The Takeaway: Early detection and action (more than 192 traps at 83-plus sites) stops this predator from wrecking the shellfish industry.

Three national estuarine research reserves—Washington’s Padilla Bay, Alaska’s Kachemak Bay, and Oregon’s South Slough—are successfully targeting the invasive European Green Crab, which poses a threat to the West Coast’s $270 million annual shellfish industry. Their rapid response, which involved setting out traps in numerous locations, is catching the danger in its early stages, avoiding the crisis Maine confronted in recent years when they saw their $25 million annual shellfish industry devastated by the invader.

This hardy native of the northeast Atlantic Ocean and Baltic Sea is a voracious eater of juvenile crab, fish, clams, oysters, and mussels. When unchecked, it outcompetes native species for food and destroys eelgrass nurseries. It also competes with birds for food and often hosts a marine worm harmful to shorebirds.

In 2016 an educator with Washington’s Padilla Bay National Estuarine Research Reserve found a European Green Crab on site. A team of research reserve staffers and local partners sprang into action, setting out 192 traps at 31 sites in Padilla Bay. Since then, just five additional green crabs have been found in the area, showing that early detection and rapid response are containing the threat. Monitoring continues on four sites within this research reserve, enabling staff members to respond quickly to any increase in the invader.

Washington Sea Grant leads the European Green Crab effort statewide, with 52 monitoring sites and nearly 100 caught. Quick action is critical to Washington’s economy, which leads the nation in hatchery-reared and farmed shellfish, hosting 300-plus farms and an annual farmgate value of more than $108 million.

Alaska’s Kachemak Bay Research Reserve has been monitoring sites for European Green Crab since 2004. Educators have incorporated the monitoring efforts into their classrooms, enlisting students as young as 10 in learning about the surrounding ecosystem and laying the traps, loaded with herring, at low tide. Throughout the years, participants have included summer cabin residents near the research reserve, tribal environmental technicians, and retired biologists.

Researchers at Oregon’s South Slough Research Reserve have documented European Green Crab “hot spots” in the Coos Bay Estuary and collected environmental data. The results enable them to better understand which factors create favorable conditions, so they can predict and target potential trouble spots. In the process, they found a trap ideal for eradicating and monitoring the invader. The findings have proven valuable to the Oregon Department of Fish and Wildlife, Oregon State Sea Grant Aquatic Invasions Program, local tribal groups, commercial fisherman, and aquaculturists.

These successes would not have been possible without hundreds of volunteers representing local organizations and agencies, tribes, students, and educators. (2018)

Partners: The Kachemak Bay, Padilla Bay, and South Slough research reserves, U.S. Fish & Wildlife Service, Washington Department of Fish and Wildlife, Washington Sea Grant