Green crab pathogen research raises concern for Nova Scotia lobster industry

New research is raising more concerns about the potential transfer of diseases from the invasive green crab to lobster in Nova Scotia waters.

Bacteria lethal to lobsters has now been found in green crab along the province's Northumberland Strait

At Dalhousie University's agricultural campus in Truro, N.S., lobsters are dissected in an effort to prove a link to pathogens found in green crab. (CBC)

New research is raising more concerns about the potential transfer of diseases from the invasive green crab to lobster in Nova Scotia waters.

"Our worry is there could be a pathogen transfer and it could damage our lobster industry. We are finding at least two pathogens of concern," said research scientist Fraser Clark.

He adds human health is not at risk.

Clark released a study earlier this year showing high levels of a parasite in green crab is being found in areas of southern Nova Scotia where the crab has been introduced as a lobster bait. 

He says a bacteria lethal to lobsters has now been found in green crab along the province's Northumberland Strait, the presence of which was only recently confirmed by genomic testing.

Clark released those findings for the first time at a U.S.-Canada lobster science symposium held in P.E.I. this month.

"On the Northumberland Strait we are finding an especially high level of pathogens in green crab that is known to kill lobsters," Clark told CBC News in an interview at a lab at Dalhousie University's Agricultural Campus in Truro, N.S.

Clark's molecular biologist wife, Sarah Stewart-Clark, also works on the research.

Connection not confirmed

Feeding trials are the next step to establish whether in fact infected green crab are passing diseases to lobsters.

Clark says the connection remains unproven but justifies caution in using green crab as lobster bait.

Nova Scotia exports nearly $400 million of lobster per year and the industry has taken note of Clark's findings. Major lobster processor Clearwater Fine foods has provided thousands of pounds of lobsters as part of the studies.

The presence of higher levels of bacteria lethal to lobsters was only confirmed by genomic testing in recent weeks. (CBC)

"We don't think this parasite is killing these lobsters, but we worry it is changing behaviour, so they may be eaten by other predators or it may limit the time they can be held live in holding," said Clark.

Lobsters with high loads of green crab parasites have a higher metabolism causing them to burn fat much faster, perhaps decreasing their ability to survive in holding tanks.

"They want to know, are areas that have high levels of parasites going to hold for a shorter period of time? That's where the industry is quite concerned," said Clark.

More study is needed on how fast a lobster infected with parasites burns its fat reserves compared to one that is not infected.

Funding for the Clarke's research project is coming to an end, so as Clark looks for answers he is also looking for dollars.

About the Author

Paul Withers

Reporter

Paul Withers is an award-winning journalist whose career started in the 1970s as a cartoonist. He has been covering Nova Scotia politics for more than 20 years.

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