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A harmful algal bloom has struck parts of Northern Norway, killing an estimated one million farmed salmon, including 250,000 smolts, in the regions of Troms and Nordland, Norwegian authorities have reported.
The bloom, caused by the algae species Chrysochromulina and Phaeocystis, has affected multiple fjords within Production Areas 9 and 10. Both algae species are naturally occurring, but in high concentrations they damage fish gills, reduce oxygen uptake, and lead to suffocation.
“It is currently estimated by the farmers that there are up to 1 million dead fish... and the number of dead fish may be higher,” said Arnt Inge Berget from the Norwegian Directorate of Fisheries, via a press release.
Earlier this month, Norway's Institute of Marine Research (IMR) confirmed the presence of Chrysochromulina in multiple sites, including Salangen and Ibestad. Dispersion models show the bloom moving between connected fjords and potentially spreading further in the coming days, according to IMR scientists.
Several companies are continuing clean-up operations, the Directorate of Fisheries reports. Presenting its first quarter results this week, salmon farming firm SalMar confirmed it had also been affected by the algal bloom at one of its farming sites.
The Directorate of Fisheries said it is working closely with the Norwegian Food Safety Authority and the Institute of Marine Research to monitor developments and provide necessary support to the industry.
"Farmers are asked to monitor signs such as changed behaviour 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.