Aqua Tromøy Keeping it Fresh

Mowi’s vessel, Aqua Tromøy, continues to deliver freshwater baths that aid fish welfare

Freshwater baths continue to provide environmentally friendly fish health treatments to salmon raised at Mowi Canada West (MCW) farms, with recent treatments occurring at locations in the north east region of Vancouver Island.

Added to Mowi’s fleet in 2019, the 77 metre-long Aqua Tromøy is equipped with a reverse osmosis system (also known as desalination) that creates freshwater from seawater in preparation for bathing salmon to effectively remove marine parasites (e.g. naturally occurring sea lice) and to improve gill health. All water discharged from the vessel has been filtered to remove particulates including individual sea lice.

Gerry Burry, Treatment Manager at MCW, explains further: “Freshwater is a gentle, non-chemical and effective sea lice management tool that improves fish welfare and ensures sea lice on our farms are maintained at very low levels.”

The reverse osmosis system can produce 3000 cubic metres of fresh water in approximately 12 hours. Further explaining the process, Gerry adds: “During the process of creating fresh water from sea water, the vessel is required to maintain its position in a safe protected area away from current and weather for stability reasons. The seawater being used to create the freshwater would need to have minimal organics and suspended solids for the most efficient use of the reverse osmosis system. It is normal practice for the vessel to find clean water in a protected area where they are not a hazard to navigation and less impacted by current and tide.”

There is no designated zone for reverse osmosis activity, and depending on the sea site location weather conditions and current the location may change day to day.