Shocking sea lice: Cooke Aquaculture tries non-chemical answer at salmon farm

A Bay of Fundy fish farm is using a new non-chemical method to combat sea lice.

Cooke Aquaculture has been testing out the Thermolicer for a few years. This week its new boat the Miss Mildred hit the water, equipped with one.

The Thermolicer was created by the Norwegian company, Steinsvik. The Miss Mildred stops by a fish pen, and through Thermolicer tubes the fish are sucked into the hull. They're submerged in a warm-water bath for around 30 seconds, then spit out into another pen.

The sea lice are shocked off because they can't handle sudden changes in temperature, and are moved to a compost bin.

Joel Richardson, vice president of public relations with Cooke Aquaculture said the company hopes using this tool, which cost $10-million to develop and test, will help reduce reliance on chemicals used to treat sea lice now.

"It will remain to be in full operation throughout the spring and summer seasons and it can move around to different farm sites in New Brunswick," he said.

The problem with sea lice

Mark Hambrook, president of the Miramichi Salmon Association, said while sea lice are naturally occurring and are found on salmon travelling upriver, they become a real problem when salmon are farmed in large numbers.

"They're so numerous that they actually instead of being a troublesome parasite they become a life-threatening parasite," Hambrook said.

Sea lice grab onto the body of the fish and eat the mucus on the surface of their skin. Hambrook said that's not usually a problem, but when there are lots of sea lice, they can start hurting the fish, depleting its energy and finally killing it.

Richardson said the Thermolicer will leave the fish unharmed and will have no impact on wild salmon and sea lice outside of the area where Cooke Aquaculture is farming.

"It has no impact on wild salmon or any other marine species," he said.

Striking a balance

Richardson said most salmon farmers know that it's expensive to use chemicals and "medicines" to help prevent sea lice from killing the salmon product, which is why many companies in Europe and the U.S. have been using it.

Matt Abbott, the Fundy baykeeperwith the Conservation Council of New Brunswick, said illegal sea lice treatments have historically been harmful to lobsters and krill.

In 2013, Kelly Cove Salmon, a division of Cooke Aquaculture,pleaded guilty to two charges in connection with the deaths of hundreds of lobsters in the Bay of Fundy from an illegal pesticide in 2010.

Richardson said that while all treatments used by Cooke Aquaculture are legal and approved byveterinarians, Health Canada and the Canadian Food Inspection Agency, the company still wants to move away from that practice.

Abbott said fish farmers are faced with the challenge of balancing what would kill the sea lice and have minimal harm on the rest of the fish and total ecosystem.

A human error mishap

In 2016, a Scotland-based salmon farming company accidentally killed almost 100,000 fish by putting them through the Thermolicer too soon after the fish went through a chemical treatment for a different disease.

Marine Harvest Scotland blamed human error on the death of the fish.

Steve Bracken Business Support Manager at Marine Harvest Scotland told CBCNews that nothing like that has happened again.

"After the initial problem at startup, it is now performing well and features among other measures we adopt to deal with sea lice," Bracken said in an email exchange.

Abbott said the Thermolicer is a step in the right direction, but an ideal world would have no pesticides at all.

"We certainly are happy to see efforts that may reduce pesticide use in the ocean but it remains a chronic problem and when you're farming almost at a feedlot scale then pesticides will remain in the mix," Abbott said.