An algal bloom in Norway's aquaculture production areas nine and 10 has led to fish mortality for several fish farmers in Nordland and Troms.
The Norwegian fisheries directorate (Fiskeridirektoratet) said it was following developments closely and that it was in continuous dialogue with affected parties.
The highest mortality was reported between May 10–12 in production area 10, particularly in the area around Astafjorden. Four companies are affected to varying degrees.
"There have been challenges with handling dead fish, but all farmers have stated that they have the situation under control," said the Fiskeridirektoratet.
"It is currently estimated by the farmers that there are up to one million dead fish, of which 250,000 are smolts," said Arnt Inge Berget, section manager for the aquaculture supervision and guidance section at the Fiskeridirektoratet.
"Clean-up is still underway in cages where fish have sunk to the bottom, and the number of dead fish may be higher. Warnings and measures have been implemented."
The Fiskeridirektoratet warned farmers in PO10 early on about the possibility of spread from PO9, and urged increased preparedness.
"Farmers are asked to monitor signs such as changed behavior in the fish, reduced visibility in the water and increased mortality. It is important to notify us quickly if this is the case, said Berget.
Two types of algae are linked to the incident: Phaeocystis and Chrysochromulina . These can both secrete substances that affect the gills of the fish and make it difficult for them to absorb oxygen.
