The company has been trialling the use of freshwater treatment in New Brunswick but had to make a considerable effort to find the water it required to fill the tanks of the 1,040m³-capacity Viktoria Viking wellboat that is on contract from Intership.
“We sailed over six hours to Nova Scotia to source the water, working with a company called Clear Water Supplies,” said Mowi area manager Allene Barrett told the company’s InSite newsletter.
“We actually had to dock the wellboat in Yarmouth because the size of the vessel meant we could not get that close. Then tankers were used to transport the water to the Viktoria Viking (40 loads worth) before we set sail back to New Brunswick.”
New for Canada East
Freshwater treatments are new for Mowi Canada East’s managers, who did a lot of research and spoke to colleagues in other business units, including Scotland, before embarking on the first treatment.
Preparations included ordering bespoke dewatering boxes to ensure that no salt water could get into the wells.
Barret told InSite: “We started off cautiously with small volumes of fish. First of all, we put 12 fish in the fresh water in a box and monitored them closely for an hour.
“Confident they were doing well, we then introduced 2,500 salmon into the starboard well of the Viktoria Viking where they were monitored for two hours. Satisfied with all the fish health checks, we transferred the rest of the fish from the pen, so we had close to 45,000 salmon in the fresh water where they remained for around six and a half hours.”
The treatment was successful and, when the salmon were transferred back to their pens, they started feeding straight away and the gills were in good condition.
Mowi’s team is now focused on gathering more data from the trial and looking at options to recirculate the water which would mean that four pens could be treated every four days.
Closer water sources
The company has also been able to find closer sources of fresh water, and its freshwater treatment options will increase when a new Intership wellboat on order from Spanish shipyard Zamakona Yards Bilbao arrives on a long-term contract in the first half of next year.
The vessel will have a total capacity of 2,200m³ and be equipped with a fully integrated reverse osmosis system for production of fresh water from sea water.
Mowi Canada East managing director Alan Cook said: “The freshwater sensitivity trials on seal lice from our regions along Canada’s east coast were very positive and give us confidence to move ahead with freshwater treatments being our primary choice for sea lice management in the long term, along with other effective management options used in rotation. The basis for this is twofold: fresh water is shown to be very effective for sea lice removal and is comparatively stress free on the fish.”