HALIFAX -- A journal article is suggesting evidence that Ottawa uses to claim aquaculture is environmentally sustainable is sketchy because it lacks detailed, long-term analysis.

However, advocates for the industry are suggesting the report in Marine Policy journal lacks credibility itself.

Inka Milewski, a research associate in the Department of Biology at Dalhousie University, said Monday her conclusions are partly based on a series of long-term studies of a fish farm in Port Mouton Bay, N.S.

She says evidence of an impact on lobster populations and eelgrass in the bay around those pens run counter to a "narrative" found on various federal Fisheries websites that Ottawa manages the industry in "a sustainable way."

Her report notes that Ottawa had collected reports of 14.4 metric tonnes of antibiotics and 439 metric tonnes of hydrogen peroxide pesticides being placed in the waters since federal aquaculture regulations came into force four years ago.

However, Milewski says the federal Fisheries Department isn't looking behind that to see what is happening to habitat near pens over time.

She says simply posting figures is like a doctor "giving you your medical exam results, but not telling you if you have a health problem or not."

Milewski partnered with community-based researcher Ruth Smith, who is active in the Friends of Port Mouton Bay group.

They cite a seven-year survey suggesting lobsters were displaced from a 20-square-kilometre area of the bay when the fish farm was operating, but partially recovered when it was dormant.

Milewski and Smith also cited a study published last fall suggesting an impact on eelgrass when the flowering underwater plant was near pens.

Sue Farquharson, executive director of the Atlantic Canada Fish Farmers Association, said in an email that Milewski's work is more "opinion piece than a science report."

Farquharson cites an article in the Marine Pollution Bulletin that criticized the Port Mouton lobster study's methodology and said, "there is no evidence of any relationship between fish farming activities and the lobster fishery in Port Mouton Bay."

However, Milewski's study also suggests that other "pillars" of sustainability, such as the economic and social benefits, are unclear.

It cites data from the Nova Scotia Department of Fisheries and Aquaculture indicating that while finfish production boomed between 1995 and 2017, the industry in the province employs the same number of full-time employees, while part-time employees have fallen.

"Sustainability indicators should provide the public with concrete measures of government accountability on policy narratives and goals," said Milewski in a news release.

"In the absence of meaningful measures of sustainability, Canada's declared aquaculture policy goals risk being reduced to mere political catchphrases."

Farquharson countered in an email that "aquaculture is a science-based industry."

"It always has been, and it always will be. Producers adhere to rigorous regulations as well as third party audits that use social, economic and environmental indicators to certify each farm."

She noted that lobster landings across Atlantic Canada, including Nova Scotia, have been on the upswing for the past two decades.

"It's important to point out that the latest data on antibiotic and pesticide use shows an 80 per cent reduction from 2017. Antibiotic use varies from year to year in different jurisdictions depending on a variety of factors, but the vast majority of farmed salmon never receive an antibiotic," wrote Farquharson.

The federal Fisheries Department didn't provide comment by deadline on Monday afternoon.

Keith Colwell, the Nova Scotia minister of Fisheries and Aquaculture, said in an interview that Milewski should consider that his department has increased monitoring of aquaculture sites in recent years.

He says under provincial rules, new aquaculture sites must carry out bottom videotaping and regular sampling to see what impact is occurring from the industry.

The results are audited by department scientists, who Colwell says also verify the company's sampling with their own visits.

The minister said while it's true that there are fewer jobs on aquaculture sites than in the past, the positions are more highly paid - in the $50,000 to $60,000 range - than in the past.