THOUSANDS of tonnes of farmed salmon have died following a large algae outbreak off the north coast of Norway.
A significant area in the fjords between the regions of Troms and Nordland have suffered an acute growth of the bloom and the fear is that it may spread to other important salmon farming areas.
Losses are already expected to total at least 200 million kroner (£18 million) and are likely to go higher.
The broadcaster NRK reports that one farm, Ballangen Sjøfarm, has lost some 2.7 million fish, or 3,000 tonnes, about half of its current stock.
Scientists from Norway’s Institute of Marine Research are still trying to establish the full extent and impact of the infection which has affected at least four companies.
They are also working with the farming companies to get the dead fish out of the sea as quickly as possible.
There has been some relief since the weekend when problem was at its height, with just two fresh outbreaks reported.
However, officials stress the danger is not yet over, and extra boats have been brought in to bring up the dead fish.
Norway’s Directorate of Fisheries said the biological picture was a complex one, adding that water samples have been taken in both regions to establish what type of algae is involved.
But an early analysis from one fjord shows the presence of Chrysochromulina spp. Breeders have reported that the water has been turning grey in some areas.
The Directorate said: ‘By looking at the water flows we make models that give a picture of where the algae will spread.’
It added that only farmed fish was being affected as wild fish will swim away from any outbreak. A change in the weather and wind patterns may also help to bring some relief.
Otto Andreassen, section manager at the Directorate, said it was virtually impossible to prevent algae, but a lot could be done to avoid a disaster.
‘Breeders have a contingency plan that is followed slavishly,’ he explained. ‘In the worst cases, emergency slaughter may be necessary. Salmon that die as a result of the algal bloom cannot be eaten.’