Green crabs (Carcinus maenas) are native to the Northeast Atlantic. Non-native populations exist in 6 major regions globally, including the Northwest Atlantic, where green crabs range from Newfoundland, Canada, to Maryland, U.S.A. Along the east coast of the U.S., records of the species date back to the 1800s, and populations in New York are well established. Green crabs inhabit rocky intertidal and subtidal habitats and have caused negative ecological and economic impacts throughout their introduced range.
Description
How to identify green crabs:
Green to dark brown in color
No swimming legs
Pentagon shaped carapace (shell) with 5 spines on each side of the eyes.
Carapace (shell) can grow up to 4 inches wide.
Habitat and Distribution
Green crabs are native to the Northeast Atlantic. Non-native populations exist in 6 regions globally, including the Northwest Atlantic, where the species ranges from Newfoundland, Canada, to Maryland, U.S.A. Green crabs are commonly found in sheltered intertidal and shallow subtidal habitats and occur throughout New York’s marine coastal environments.
Impacts
Green crabs have caused negative economic and ecological impacts in non-native environments.
Economic: In New England, green crabs have destroyed eelgrass beds and have negatively impacted shellfish fisheries.
Predation and Competition: In New York, green crabs consume native bivalves (e.g., blue mussels) and other invertebrates and compete with native crabs for food and habitat. However, the relative ecological impact of green crabs in New York has declined due to the arrival of another non-native species, the shore crab (Hemigraspus sanguineus). Since the arrival of the shore crab in the 1990s, shore crabs have partially displaced green crabs in rocky intertidal habitats.
Spread
Green crabs were most likely introduced to through ballast water.
Species Regulation
The green crab is a regulated species under New York State Invasive Species Regulation 6 NYCRR Part 575. Regulated species cannot be knowingly introduced in a free-living state or introduced by means that one should have known would lead to such an introduction, although such species are legal to possess, sell, buy, propagate, and transport.
Green crabs can be used as bait. The possession limit for green crabs is 50 crabs per day, and green crabs cannot be released in a free-living state. Please visit the NYSDEC Saltwater Fishing regulations for the most up-to-date information.
How You Can Help
Clean, drain, and dry your watercraft and equipment thoroughly before visiting other waterbodies.
Inspect and remove debris and mud from boats, trailers, and equipment.
Dispose of all debris and bait in trash cans or at disposal stations.
Drain all water-holding compartments including live wells, bait wells, and bilge areas. If possible, visit a decontamination station and disinfect compartments with hot water (140°F) for at least 30 seconds.
Dry boats, trailers, and all equipment before use in another water body. A minimum of 5–7 days of drying time in dry, warm conditions is recommended.
Do not dump aquarium contents in any waterbodies, drainage ditches, or sewers.
Use certified bait that is non-invasive and disease free.
Learn how to identify green crabs and report any encounters.
If you think you have found a green crab:
DO NOT RELEASE IT ALIVE.
Take several photos of it from different angles and dispose of the specimen.
Email the photos, noting where it was caught (coordinates preferred), to [email protected], OR
Submit a report through iMapInvasives
Additional Resources
National Estuarine and Marine Exotic Species Information System - information on marine and estuarine invertebrates and algae introduced to the United States – species profile for green crab
Relative impacts of two exotic brachyuran species on blue mussel populations in Long Island Sound- research paper exploring the impacts of non-native crabs on native blue mussels in Long Island Sound
