Cold winter killing salmon at fish farms

Josh Pennell Josh.pennell@thetelegram.com
Published on May 14, 2014
The bitter and prolonged cold of this winter has had a deadly effect on salmon in acquaculture facilities in the province. — TC Media file photo

Cold enough to kill a fish might just become a newly coined phrase after an abnormally frigid winter that has taken its toll on the farmed salmon of the province’s aquaculture industry.

The numbers aren’t in yet and the hope is that the losses won’t be drastic, but a percentage of farmed salmon fell victim to winter mortality.

“This is an exceptional year,” says Miranda Pryor, executive director of the Newfoundland Aquaculture Industry Association (NAIA). “The environmental conditions and the water temperatures are the coldest we’ve seen in well over 10 years.”

The fish die in what’s called a super chill event. If the fish hit a critical temperature, they can’t survive, Pryor says. It’s a rare event that hasn’t happened here in quite some time.

Rare, but not abnormal, Pryor says. The reason it isn’t known how many fish have been lost due to the super chill is that aquaculturists are still getting out to their fish cages and cleaning them up after the long winter. Normally they get out there every week, Pryor says, but when the water temperature is as cold as it was during this winter, they have to leave the fish alone. The salmon stay at a depth that has a preferred temperature.

“If we disturb them, then they would tend to swim into areas of the cage which may be colder.”

That can lead to massive mortality. So the fish farmers haven’t been out to their cages in months in some instances and are just now getting a handle on what they’ve lost.

Dead fish from the  aquaculture industry had been going to a local compost company. That company is being restructured and so that’s no longer an option. Other times — the least preferred option, Pryor says — the dead salmon are sent to the landfill.

The winter mortalities being collected now are sent to the Barry Group facility in Burgeo to be rendered into a fish meal product.

Pryor says they’re hoping to get the final numbers on this winter’s farmed salmon mortality in a few weeks.