Mowi Canada West is currently using an evolving mix of tools to battle sea lice, which the company said is allowing it to have a more efficient and integrated pest management system.

Integrated Pest Management (IPM), according to the Environmental Protection Agency (EPA), is based on taking an environmentally sensitive approach to pests that causes the least possible hazard to people, property and the environment.

"Having integrated pest management and available tools has put us in a good position to manage our farms with respect to balancing the number of treatments and keeping lice abundance low, particularly at critical times," Jeremy Dunn, director of community relations and public affairs at Mowi Canada West, told IntraFish.

Here are the four approaches Mowi is using:

The Aqua Tromoy wellboat

In April, Mowi launched what it said the "largest and most technologically advanced vessel to ever serve the Canadian aquaculture industry" in British Columbia waters.

The new wellboat, which is three times larger than any Mowi Canada West has used in the past, can treat between 50,000 to 70,000 fish at a farm site, according to Dunn.

"It was designed to treat one pen of fish at a time," he said. "It goes where the need is, and our fish health department works to schedule that. The treatments it has done have been successful. It does play a big role in our integrated pest management system."

The Atlantic salmon are lifted aboard from farm pens and immersed in fresh water, which removes sea lice and other saltwater microbes and parasites that do not tolerate low-salinity water well. Fine filters then remove parasites from the water before it is re-introduced to the ocean.

"The pumping system on the vessel is state of the art and is gentle on fish, which is really good from a stress perspective," he said.

Hydrogen peroxide

Hydrogen peroxide has proven to be an effective component of Mowi Canada West’s suite of sea lice management tools since it was introduced five years ago, Dunn said.

Mowi has been allowed to use the hydrogen peroxide Interox Paramove 50 since 2015, a drug that has been assessed by Health Canada to ensure its general use will not result in adverse impacts to human health and the environment.

Dunn said hydrogen peroxide was a game-changer for BC salmon farmers, with the only tool available prior to Interox's introduction being an in-feed emamectin benzoate, known commercially as Slice.

Slice

Introduced nearly 20 years ago, the drug is a medicated fish feed for the treatment and prevention of infestations of all parasitic stages of sea lice in salmon. However, by 2008 in Norway at least, Slice treatments that had previously seen efficacy rates as high as 95 percent suddenly dropped to 70 percent, because the sea lice developed resistance to the drug.

"Mowi has not experienced resistance to slice in BC," Dunn told IntraFish. "We have always been concerned about it, which is why we have pushed for Integrated Pest Management."

Hydrolicer

In 2018, the company introduced a hydrolicer to successfully treat fish in net pens near the Campbell River with what it touted as a drug- and chemcial-free method. The company's hydrolicer barge pulls fish from the pens into a tank where it uses pressurized water to dislodge sea lice, which are collected by filters for disposal.

A moving target

Dunn said sea lice prevention is always in the company's research and design pipeline.

"See lice are a natural parasite in the ocean," he said. "All farmers battle different parasites, whether you're farming cows, pigs, chickens or fish. We will always be working to manage sea lice, new treatment options, treatments that are non-chemical-based. That research in the industry is really important."

Aquaculture

How Mowi Canada West attacks sea lice