Hybrid Green Crab Species Threatens Northern Lobster Population

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Hybrid Green Crab Species Threatens Northern Lobster Population

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A hybrid species of crab has been identified in Canadian waters off the southern coast of Newfoundland that is impacting the lobster population  by eating lobster spawn. The crabs are described as being “born ferocious” by scientists and will not only eat lobsters, but also clams, scallops, and each other!

The Frankenstein-looking green species combines genes from a population originating in eastern United States with another population coming form northern Europe.

“So what we have is a population that is hybridized, mixed, that is very cold-tolerant,” said Cynthia McKenzie, scientist with the Department of Fisheries and Oceans based in St. John’s. “And of course, there are little to no predators here, and so they’ve just exploded.”

Although McKenzie says the crabs can live weeks out of water, the crabs have flourished in the frigid Canadian waters and have provided a perfect environment for this newly identified species to thrive.

But how did they get here?

Scientists say the crabs probably arrived through shipping from Northern Europe through the Halifax area, McKenzie said. Fishermen in the area say they first noticed the hybrid species back in 2007, and the creatures have spread quickly through the bay. Now, they are moving to nearby Fortune Bay, which is home to a large lobster fishery – and could have devastating consequences on the lobster population.

McKenzie says lobster catches were already in decline in the area, but it is almost certain the green crab is partially to blame.

Local fishers are concerned about catches

Clarence Marsh, a Canadian Fisherman, told CBC News, “When a lobster spawns…the green crab is there to eat it. I think the green crab has got a big effect on the lobsters, and that’s why there’s none here in this bay now.”

Mash also observed there are plenty of crabs, and they don’t just eat lobster – he finds hundreds and hundreds of empty scallop shells with tiny green crabs in them.

Is there a market for the green crabs?

Unfortunately, no. Experts say there isn’t a viable market for the green crabs, unlike the much larger snow crab. The creatures are exceptionally small; only 10 centimetres across. Due to their size, they contain very little meat and therefor would be hard to harvest.

How to prevent further spread

After seeing the ecological harm the green crab caused in Placentia Bay, McKenzie hope to prevent a widespread invasion elsewhere. She warns that the crabs can be transported in gear or in boats without anyone noticing because people think crabs die out of water – but not so with this hybrid! 

Marsh would like to see a government-issued license to catch them, although McKenzie says that eventually, local predators will do their part to reduce the green crab infestation.

Why raising lobsters on land can help save the population

At CSF, we believe in protecting the lobster population by raising them sustainably on land. Due to natural causes, only 1 in 1,000 baby lobsters survive their first year of life – and with threats like the green crab and other invasive species, this high mortality rate could potentially increase.

We catch these baby lobsters so they are save from predators and we provide them with an abundance of food. This process is biologically-neutral and is the most sustainable ways to support the natural population. 

Interested in learning more, or investing in the future of our fishery? Please contact us here.

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