An eight-year study of lobsters living below a salmon farm off New Brunswick's Grand Manan Island found the aquaculture operation had no impact on the crustaceans' abundance, size or growth.
The peer-reviewed, industry-funded study was published this month in the Canadian Journal of Fisheries and Aquatic Sciences.
Its authors say it's the most in-depth examination of its kind in Atlantic Canada.
"There isn't anything like this. Any surveys that have been done have been sort of cursory," said Jon Grant, the study's lead author and a Dalhousie University oceanographer.
How the study worked
The study involved divers visiting a sample area under the Benson Aquaculture salmon farm at Cheney Head off Grand Manan in 2008, and returning every August and September.
To establish a baseline, surveying started before the fish farm opened. The study covered two production cycles at the farm, which uses pesticides to control sea lice and has been opposed by lobster fishermen.
It also included a fallow period and a farm expansion to 336,000 fish from 10,000 during the second production cycle.
An identical survey was conducted about a kilometre outside the farm.
By the time the project ended in 2015, divers had counted 1,255 lobsters inside the farm and 1,171 outside.
What the study found
"In both cases, whether it was on the farm or off the farm, over those eight years the abundance of lobsters went up. A lot. By 100 per cent or more. And there was no difference in those lobsters in any way — in their size, in their sex or their abundance, whether on or off the fish farm," Grant told CBC News.
"We don't detect any evidence that the fish farm affected behaviour, growth or abundance of those lobsters."
He said the study proved one hypothesis: the population inside or adjacent to the farm matched growth seen elsewhere in lobster fishing areas.
"It reflects the fact that the fishery is ongoing and it's thriving and that fish farming does not seem to have impacted it, at least in eastern New Brunswick," said Grant, who is funded by New Brunswick-based Cooke Seafoods and holds the NSERC-Cooke industrial research chair in sustainable aquaculture.
Surveys ordered by government regulators
The surveys were a requirement of the federal Department of Fisheries and Oceans and the New Brunswick government. The Atlantic Canada Fish Farmers Association funded the study.
The field work was carried out by SIMCorp, a New Brunswick-based marine environmental consulting firm that works for the aquaculture industry in Atlantic Canada and Maine.
SIMCorp is recognized as the standard for aquaculture, said Grant.
Tara Daggett, a SIMCorp biologist and co-author of the study, said the results are encouraging news for the aquaculture industry.
"We can fairly say aquaculture can coexist with fisheries and other species. It has a place," she told CBC News.
However, Daggett cautioned the results only reflect what happened at one fish farm.
"The fish farm is typical of Grand Manan with sandy and cobbled bottom, but in science we don't extrapolate. We need to test at other sites."
Grand Manan reaction
Melanie Sonnenberg of the Grand Manan Fishermen's Association says a long-term study like this was overdue and the results are good news.
But, like Tara Daggett, she says it's just one location and more studies are needed.
"We still need more information about the impact of medicated feeds and pesticides especially in juvenile lobster," Sonnenberg tells CBC News.
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