European Green Crab
Carcinus maenas
Learn about European Green Crab, including its identifying features, location, habitats, impacts and our response.
On this page
- Identifying features
- Where is the species invasive
- Distribution
- Habitat
- Impacts
- Response
- Photo gallery
- Maps
- Related links
Identifying features
The European Green Crab (Carcinus maenas) is a small coastal crustacean. You can identify it by its:
- shell that:
- is serrated and pentagon-shaped
- has five sharp spines on the side of each eye and three rounded lobes between the eyes
- back leg tips that are:
- hairy
- pointed
- slightly flattened
- different sized front claws
- size, which can be up to ten centimetres
- colour that varies from green to red or yellow
- temperament that is:
- territorial
- aggressive
If you think you have seen a European Green Crab, report it.
Nearshore native crabs found in eastern Canada that look similar to the European Green Crab include:
- Rock Crab (Cancer irroratus), which:
- is larger (up to fifteen centimetres)
- has a broad oval shaped shell that can be red/brown or purple
- has nine rounded lobes on either side of the eyes
- Jonah Crab (Cancer borealis), which:
- is larger (up to eighteen centimetres)
- has a scallop-shaped shell
- has nine rounded lobes on either side of the eyes
- Lady Crab (Ovalipes ocellatus), which:
- has oval tips on its hind legs
- has five spines on either side of the eyes, like the European Green Crab
- is white to yellow/grey, with red/purple spots
Nearshore native crabs found in western Canada that are green in colour and can be mistaken for European Green Crab include:
- Northern Kelp Crab (Pugettia producta), which:
- has a pronounced pointy nose
- has a shell that is longer (front to back) than it is wide
- Helmet Crab, also called Hairy Helmet Crabs (Telmessus cheiragonus), which:
- are covered with bristles and bumps
- has a diamond shaped shell
- Hairy Shore Crab (Hemigrapsus oregonensis), which:
- has three spines on either side of the eyes
- has a square shell
Where is the species invasive
In Canada, European Green Crab has invaded:
- New Brunswick in 1951
- Nova Scotia in 1953
- The Gulf of St. Lawrence in 1994
- Prince Edward Island in 1997
- British Columbia in 1998
- The Magdalen Islands, Québec in 2004
- Newfoundland and Labrador in 2007
Although they look the same, there are different populations of European Green Crab found in eastern Canada. The first population spread into Atlantic Canada in the early 1950s, moving north from the eastern North Atlantic seaboard and are not cold tolerant.
A second population arrived in the 1980s and 1990s in northern Nova Scotia and are better suited to survive colder waters as they originated from populations in northern Europe. These two populations have mixed and reproduced forming a third cold tolerant hybrid population that is also rapidly spreading both north and south in Atlantic Canada.
Established populations of European Green Crabs have been found on the west coast of Vancouver Island. Since 2018, new detections of European Green Crab have been found on: northern Vancouver Island (Port Hardy); southern Vancouver Island (Esquimalt Lagoon, Witty’s Lagoon); the Gulf Islands (Salt Spring Island); Haida Gwaii and, in southern British Columbian waters (Boundary Bay).
Distribution
The European Green Crab is native to Europe and North Africa. It likely arrived in North America around 1817 carried in the holds of wooden ships.
European Green Crabs are thought to spread during their long larval stage (up to 90 days) through shipping (ballast water transfers) or by drifting on ocean currents. They can also move from one area to another by hitchhiking unseen on boats and gear or in packaged shellfish.
Habitat
The European Green Crab are found near shore, usually in shallow waters less than 6 metres. They can tolerate a wide range of water temperatures and salinities (salt content of water). They are found in:
- salt marshes
- vegetation, including eelgrass beds
- rocky coasts
- sandy beaches
- sheltered areas
- shallow water on bottoms that are sandy, muddy, or pebbled
The adult European Green Crab is very hardy and can survive out of water for five or more days. Its hiding places include:
- crates
- boats
- buckets
- fishing gear
- aquaculture gear
- equipment
Impacts
The European Green Crab is highly resilient and can upset the balance of estuarine and marine ecosystems, impacting biodiversity. European Green Crab:
- live 4 to 7 years
- can eat a wide variety of plants and animals
- females can release up to 185,000 eggs once or twice per year
Ecological impacts
European Green Crab impact native ecosystems by:
- destroying beds of shellfish
- feeding on native animals, including:
- clams
- oysters
- mussels
- small fish
- juvenile crabs
- other crustaceans, including juvenile lobster
- out-competing native crab species for food
- disrupting eelgrass beds, which are habitats for many juvenile fish species
Socio-economic impacts
European Green Crab impact the fishing and aquaculture industries by:
- damaging eels when they enter the traps
- reducing the abundance of harvested species by:
- out-competing native crab and lobster for food and shelter
- feeding on shellfish, including juvenile lobsters, as well as small and juvenile fish
Response
Once European Green Crab have established a population in an area, it is practically impossible to eradicate them. However, we can limit their spread and the damage they cause.
Fisheries and Oceans Canada is collaborating with many partners including:
- academia
- fish harvesters
- Indigenous Peoples
- conservation groups
- community members
- provincial and territorial departments
- United States
We provide training on proper identification, sampling methods and data collection standards. Appropriate licencing to detect early invasions and to control populations of European Green Crabs are available in some areas. If your organization is interested in partnering, please contact us.
Where sustained removal of European Green Crab has taken place, the catch rate for these crabs has decreased considerably and native species have regained their territory.
Photo gallery
Maps
Related links
- European Green Crab in Newfoundland Waters
- Identification Booklet of marine species in Eastern Canada
- Risk Assessment for European Green Crab (Carcinus maenas) in Canadian Waters
- DFO-Washington transboundary action plan
- A Biological Synopsis of the European Green Crab, Carcinus maenas
- Habitat alteration by invasive European green crab (Carcinus maenas) causes eelgrass loss in British Columbia
- Distribution and biological characteristics of European Green Crab, Carcinus maenas, in British Columbia, 2006 - 2013
- Ecological Assessment of the Invasive European Green Crab (Carcinus maenas) in Newfoundland 2007-2009
- Hide and seek: habitat-mediated interactions between European Green Crabs and native mud crabs in Atlantic Canada
- Linking eelgrass decline and impacts on associated fish communities to European Green Crab Carcinus maenas invasion
- Temporal dynamics of genetic clines of invasive European Green Crab (Carcinus maenas) in eastern North America
- Using the Quantitative Biological Risk Assessment Tool (QBRAT) to predict the effects of the Green Crab, Carcinus maenas, in Atlantic Canada
- Date modified: