A broad-based coalition is calling on Prime Minister Stephen Harper to halt proposed changes to federal aquaculture regulations, warning they could damage the environment and existing businesses.

The proposed amendments to the federal Fisheries Act would exempt the aquaculture industry from provisions that "prohibit the release of deleterious substances into water frequented by fish."

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The proposed changes could lead to the discharge of increasingly powerful pesticides and other potentially damaging substances into the aquatic ecosystem, the coalition says. (Andrew Vaughan/The Canadian Press)

Coalition members are worried the changes will result in pesticides routinely being dumped into the Bay of Fundy and remove Environment Canada's role in aquaculture activities, said spokeswoman Maria Recchia, the executive director of the Fundy North Fishermen's Association.

The coalition wrote an open letter to Harper on Tuesday, with 120 signatories, including business leaders, commercial and recreational fishing associations, scientists, lawyers and environmentalists.

"In essence, in the end, we are going end up with the aquaculture being essentially self-regulated and self-monitored," said Recchia, who is based in southwestern New Brunswick.

"And I think we're going to have a much worse style of management than we have now and it's going to be a lot more problematic for the marine environment."

'To have DFO authorize pollution from a coastal industry is simply baffling.' - Stewart Lamont, Tangier Lobster

Stewart Lamont, owner of Tangier Lobster in Nova Scotia, agrees.

"The value of our industry is based on a pristine, non-polluted marine environment," Lamont said in a statement.

"We have already dealt with the impacts of pesticides, and see federal fines levied on something that would now become legal. To have DFO authorize pollution from a coastal industry is simply baffling," he said.

In 2013, a New Brunswick aquaculture company was ordered to pay $500,000 after pleading guilty to two charges in connection with the deaths of hundreds of lobsters in the Bay of Fundy from an illegal pesticide about three years prior.

The penalty against Kelly Cove Salmon Ltd., a division of Cooke Aquaculture, was the largest ever imposed in New Brunswick for environmental violations under the federal Fisheries Act, an Environment Canada official had said.

Two studies released earlier this year by Fisheries and Oceans Canada found two pesticides used to fight sea lice in the salmon farming industry have potential lethal effects.

Salmosan​, a pesticide currently approved for use in the Bay of Fundy, can be hazardous to lobsters and other species hundreds of metres from a farm, the research conducted at the St. Andrews Biological Station showed.

Meanwhile, Alphamax, which was temporarily used during a sea-lice infestation five years ago, could kill lobsters up to 10 kilometres away, the studies found.

Sea lice are a parasitic crustacean that feed on the flesh of farmed salmon until the salmon die or the sea lice are removed. 

The draft changes to the Fisheries Act have been in the works since 2011 and are close to being passed, said Recchia.

"These regulations will set back Canadian aquatic environmental protection measures several decades," Bill Ernst, a retired Environment Canada toxicologist, said in a statement.

"They will eliminate Environment Canada’s role in enforcing the law with respect to aquaculture and hand responsibility over to Health Canada, who do not have an undivided environmental protection mandate."