03/05/2015 14:16 EST | Updated 05/05/2015 05:59 EDT

Superchill fish kill at Nova Scotia aquaculture sites raise questions

Some Nova Scotia residents and environmental advocates are raising questions after decaying fish carcasses began washing up on a beach near an aquaculture facility this week. 

In a YouTube video shot by Ron Neufield Tuesday in  in West Green Harbour, N.S., aquaculture pens can be seen in the background. 

"I've lived in West Green Harbour for 55 years and in that 55 years I've never seen a salmon along these shores in any state. Within the past week, I've picked up two salmon carcasses. I guess the question of the day is where did these salmon come from?" he says in the video, holding up the dead fish. 

Earlier this week, the Department of Fisheries and Aquaculture announced that fish at three aquaculture sites in the province have died and a so-called superchill is the expected cause. 

Cooke Aquaculture's sites in the Annapolis Basin, Shelburne Harbour and Jordan Bay are reporting mortalities, officials said.

The Department of Fisheries and Aquaculture said superchills happen every five to seven years and the deaths do not pose a risk to the environment.

'Industry has some fundamental flaws'

However, Ray Plourde with the Ecology Action Centre disputes that a rare anomaly is to blame. 

"To suggest that this is some kind of anomaly that happens once every seven years or whatever like an El Niño event is completely false. It happened last year, it happened the year before where fish completely froze in these pens," he said.

"This industry has some fundamental flaws in the model and it makes it fundamentally risky for the operators, but also for the public, which have provided an awful lot of public money into this industry."

Plourde calls the idea of ocean aquaculture pens "fundamentally flawed." 

"[The aquaculture model] hasn't evolved an iota since it originally was thought up — which is stick a bunch of fish in a big open net bag in a coastal area, feed them, raise them up, slaughter them and send them to market," he said. 

He said the problem is the inability to control interactions with the natural environment. 

"Those include parasites, sea lice, disease and weather. In the extremes, in the warmest period of the summer the fish can be starved of oxygen because the water has become too low and the oxygen-carrying capacity has been reduced," said Plourde. 

"Similarly in the winter, when it gets too cold, the oxygen level goes down and in the case of extreme cold weather it literally freezes them alive, which has got to be a grisly way to die."

He said the solution is to move fish farms to a closed containment system on land which allows producers to control all the variables.

Nell Halse, speaking for Cooke Aquaculture, admits that "weather is an ongoing challenge."

"Cold water is the definite cause. We just don't know the extent of loss yet," she said.

"Salmon grow best when water temperatures are stable within 0 and 12 C. Fish survive temperatures below zero but a phenomenon known as superchill may occur and result in fish mortalities."

Halse said this winter's cold temperatures "have resulted in higher than normal mortalities on some of our Nova Scotia farms."  

She confirmed that the loss is covered by the companies insurance.