An invasive crab species that has been in the Maritimes since the late 1990s is migrating further north as climate change makes regions such as Labrador and Quebec more hospitable. If the crab populations aren’t contained, they could cause millions in damages to Atlantic Canada’s economy, say researchers.
The crustacean in question is the European green crab—a small yet aggressive creature that hails from both Norway and southern Europe. While the crab is just now making its way to northern Canada, the species has been in North America since 1817, says Piero Calosi, a professor of evolutionary physiology and biology at the Université du Québec à Rimouski.
After first arriving in New England from Spain and Portugal via the ballasts of ships, the crabs soon migrated to Nova Scotia and New Brunswick. By the 1980s, a cold-water adapted strain from Norway landed in the frigid waters between Nova Scotia and Newfoundland. The two strains eventually converged in Nova Scotia and created a hybrid European green crab that has been slowly travelling to the northern ends of the Maritimes and even to Chaleur Bay, on the southern border of Quebec.
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Since 2004, a notable population has also invaded the Magdalen Islands, located off the northwest coast of Cape Breton. This is where Calosi says the crabs have made their most recent jumping off point, alongside New Brunswick’s northern coastal waters. The fear is that they will successfully make the jump to the north coast of Quebec, but also from Newfoundland to Labrador.
“They move quite fast. They colonize new areas quite rapidly,” says Calosi. “The fishermen in the south side of the Gaspé Peninsula told us already that every few years, they find green crabs in their lobster pots.”
As of now, the invasive crabs haven’t fully established themselves in the region, but Calosi says it’s just a matter of time. “At some point, there will be enough individuals to reproduce and to colonize.”
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Since the crabs feast on several key aquatic species, including clams, sea plants, and even baby lobsters, their continued colonization of Atlantic Canada could have massive impacts on the health of marine ecosystems in the region. In New England, for example, the European green crab is responsible for a 75 per cent decrease in clam production.
“A hungry green crab can eat around 20 clams in one hour,” says Calosi. “And these are small individuals, but there are hundreds of thousands in some places.”
On top of the environmental damages, Atlantic Canada’s fisheries and aquaculture industries could take a massive hit, with researchers predicting between $8.79 and 22.86 million in losses.
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While it’s unknown when exactly the crabs will arrive in more northern climes, Calosi and his team of researchers are using climate change data and analyzing the temperature tolerance and movements of the hybrid species to provide a projection.
To help slow the spread of the European green crab and other invasive species, the Canadian government has imposed rules; these include ballast water regulations and mandatory cleaning, drying, and draining of boats and marine equipment. On top of that, says Calosi, Fisheries and Oceans Canada travels to the Magdalene Islands most years to set traps and remove as many green crabs as possible.
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