Invasive species

European green crab

What is a european green crab

It is a small, near-shore crab with a shell up to 10 centimetres wide. It is usually green but can be reddish-orange or tan with darker or yellowish spotting. The shell is shaped like a trapezoid with five obvious “teeth” along the top edge on each side. there are actually two different types of green crabs found in eastern Canada. the first green crab populations that invaded the Bay of Fundy and Atlantic coast of Nova Scotia are different from the green crab populations that arrived in the 1980s and 1990s north of Halifax and in the Gulf of St. Lawrence. The crabs found in the more northern waters are better able to survive in the colder waters.

Where they are from

originally the crabs where from the north atlantic coast of europe and north africa. Its speculated that the crabs first arrived in north america around 1817. the crabs most likely stayed in the holds of wooden ships while they were travelling to north america. the crabs are thought to spread in their larval stage through the water

How they got here

The european green crabs were first found in canadian waters in 1951 and have expanded across many locations in atlantic canada. they entered nova scotia waters in 1953/4 and reach south of halifax in 1966. by 1982-1983 green crabs were seen along the eastern shore of Nova scotia. they entered the Gulf of St. Lawrence by 1994 and Newfoundland in 2007.

How and where do they live

Green crabs are found in shallow ocean waters and they preferred sheltered areas. The green crab can live four to seven years and can withstand a wide range of water temperatures and salinities

How they are an invasive species

Females can release up to 185,000 eggs once or twice per year. They have a larval stage of 50 to 80 days when they drift in the ocean current before settling to the bottom. The adult green crab is very hardy and can survive out of the water for five or more days, hiding in fishing gear and equipment or, at the bottom of crates, buckets and boats. It is an aggressive crab and a forceful predator, feeding upon many shellfish species and even small fish. the European green crab invaded canada and is eating animals from other predators food chains. they are aggressive and may even battle other animals for the prey. Green crabs compete with native crabs and lobster for food and shelter, reduce invertebrate and fish diversity, can destroy shell fishbeds and threaten shellfish aquaculture