A conservation organization says no wild Atlantic salmon returned to the Magaguadavic River to spawn this year for the first time in 25 years and salmon farming along the Bay of Fundy is at least partly to blame.

The Atlantic Salmon Federation says the loss of wild salmon in the Magaguadavic is "another blow" to the outer Bay of Fundy population, which, despite a stocking program over many years, is considered endangered by an expert panel.

"The Magaguadavic should be a cautionary tale," federation president Bill Taylor said in a statement Thursday. "Throughout North America no new open net-pen salmon aquaculture sites should be allowed in proximity to wild salmon rivers."

The executive director of Atlantic Canada Fish Farmers promptly fired back, saying the federation should be challenged for "floating hypothetical assumptions as science to continually blame salmon farming for the demise of wild Atlantic salmon."

Susan Farquharson said salmon farms are equally "disheartened" by the lack of returns of wild salmon to the Magaguadavic River, which originates at Magaguadavic Lake in York County and flows 88.6 kilometres southeast through Charlotte County to empty into Passamaquoddy Bay at St. George.

Many factors at play

But it is "well known and well documented" that wild Atlantic salmon populations are impacted by a variety of issues, Farquharson said in a statement.

"Marine survival is considered the most significant factor and this is being compounded by climate change," she said.

Other factors include acid rain, industrialization, seal predation, unhealthy watersheds, hydro dams, habitat loss and over fishing.

escaped salmon

Nine escaped salmon were collected from the trap at the top of the Magaguadavic fishway on Sept. 13, says the Atlantic Salmon Federation. (Atlantic Salmon Federation)

The Atlantic Salmon Federation acknowledges the other issues, but maintains open net-pen salmon aquaculture in the bay and escaped farmed salmon breeding with wild salmon are also contributing to declining numbers.

The Magaguadavic was first "exposed" to this "threat" in the 1980s, said the group.

In 1983, Fisheries and Oceans Canada estimated 900 wild salmon entered the river to spawn, the federation said. By comparison, there were none this year, two last year and 10 in 2015, according to the salmon federation.

The area currently has one of the highest concentrations of industrial salmon farms in the world, the statement said.

Interbred fish 'less fit for survival'

Every year since 1994 — except 2006 and 2011 — more aquaculture escapees than wild fish have been counted at the Magaguadavic fishway, the group said.

And this year is no exception, with 17 escapes being removed from the trap at the top of the fishway, including two on Thursday.

"Studies have proven that escaped aquaculture fish have interbred with wild salmon in the Magaguadavic and throughout the Bay of Fundy resulting in a loss of local adaptation," the statement said.

"It is widely acknowledged that aquaculture-wild hybrids are less fit for survival and the presence of escapes and hybrids among wild populations is associated with major declines."

Points to larger escape event

The federation contends the number of recovered escapees indicates a larger escape event that has yet to be discovered or reported.

"Our experience tells us that only a small portion of escapes enter the Magaguadavic," said Jonathan Carr, executive director of research and environment.

In 2005, when 50,000 fish were cut loose at Deer Island, only 30 matching that description came back to the fishway, he said.

The Atlantic Canada Fish Farmers Association said its members have "conducted thorough investigations," in addition to its routine equipment-monitoring programs, and found no breaches of containment to explain the recent discoveries.

It contends escape events are "rare" and usually related to extreme weather.

There are about five million farmed salmon in southwestern New Brunswick in any give year, the statement said.

"Occasionally a small number of fish may escape" because of a human error during handling the fish for harvesting or inspections, it said.