The European green crab (Carcinus maenas) is an invasive species that threatens Nantucket’s native species and eelgrass habitats. Their diverse diet, tolerance of a large range of ocean temperatures, and long larval period makes them excellent at conquering new environments. Green crabs are generally regarded as one of the top five most invasive species in the marine environment.
European green crabs were first introduced to North America in the 1800s, likely traveling in ballast water of merchant ships from Europe. This species has since drastically increased in number and spread to all of New England and as far north as Newfoundland, Canada. Subsequent introductions in South America, Asia, Africa, Australia, and the west coast of North America have caused concern globally.
Here in New England, green crabs have few predators. They are faster, more aggressive hunters than most local crabs, allowing them to successfully multiply and outcompete local species for food and shelter. These invaders are extremely efficient predators of clams and scallops and destroy seagrasses while hunting and burrowing. Green crab populations in New England have been associated with crashes in shellfish populations, reduced biodiversity, destruction of eelgrass beds, and declines in native crab species.
The green crab is now abundant on Nantucket and specifically threaten three important marine resources:
- Nantucket’s biodiverse eelgrass beds, that protect our shoreline from erosion, are destroyed when green crabs cut them down to hunt and burrow near their roots.
- Nantucket’s shellfish populations including quahogs, soft-shelled clams, and bay scallops could see large declines due to predation from green crabs.
- Native crabs species, such as the common spider crab and black-fingered mud crab are threatened by direct predation and competition from green crabs.
You Can Help!
Join the Maria Mitchell Association and the Nantucket Land Council during the 1st Annual Nantucket Green Crab Week, August 10th – 14th to learn more about this threat, participate in citizen science research, and learn how to collect, cook, and use green crabs in a variety of ways. Events include videos, live demonstrations and lectures, and a citizen science activity. Check here for details!
Nantucket Green Crab Week 2020
Monday, August 10th
- The Green Crab Problem (YouTube Video)
- How to Identify Green Crabs (YouTube Video)
Tuesday, August 11th
- Research Demonstration with the Nantucket Land Council (YouTube Video)
- Green Crab AMA with MMA Aquarium Director Jack Dubinsky (Live Zoom)
Wednesday, August 12th
- Help Us Monitor Nantucket’s Green Crab Population (YouTube Video)
- Release Nantucket Green Crab Survey (Ongoing Citizen Science Activity)
- MMA Science Speaker Series with James Elliot. “Life History and Population Dynamics of Green Crabs (Carcinus maenas)” (Live Zoom)
Thursday, August 13th
- Green Crab Cooking Demonstration with Mary Parks (Live Zoom)
- How to Make Green Crab Broth (YouTube Video)
Friday, August 14th
- How to Use Green Crabs as Fishing Bait (YouTube Video)
- How to Incorporate Green Crabs into Compost and Fertilizer (YouTube Video)