Photo: Glacier Media

A new 70-metre vessel equipped with technology to remove sea lice from farmed salmon has arrived in B.C. from Norway to work for Grieg Seafood B.C. Ltd.

The Ronja Islander is moored at Ogden Point near Victoria and will service Grieg’s Atlantic-salmon farms around Vancouver Island and the Sunshine Coast.

Lice occur naturally in the environment, but farm critics worry they multiply at fish farms and put wild stocks at risk.

“It is our responsibility to make sure we do not allow [sea lice] to harbour on farm sites and increase in number,” said Dean Trethewey, Grieg’s seawater production director. “Because when the smolts are ready to go back out to the ocean in March, April, May and June, we need to make sure our [sea lice] numbers are very, very low.”

The ship – a kind of closed aquarium – will be doing battle with parasitic lice latched onto farmed salmon.

Huge hoses will suck salmon out of net pens into the ship’s hold to be immersed in a solution of hydrogen peroxide and sea water for 20 minutes, before being flushed back into pens.

About 90 to 95 per cent of lice will be removed, Trethewey said.

Ultra-fine filters capture lice, which will be incinerated on board.

The entire process will typically take about two hours. It was designed to be as gentle as possible on fish, he said.

The latest technology is used on the custom-built 2019 vessel, which Grieg has chartered for five years, Trethewey said. That includes ultraviolet light to disinfect the water and kill viruses – a major concern among fish-farm critics.

About 50,000 fish can be treated at the same time in the hold, which has a capacity of 1,800 cubic metres, he said.