A mass mortality event at a salmon farming site operated by Mowi in Nordfjord last autumn, in which close to 300,000 fish died, was closed without further action by the Norwegian Food Safety Authority but has now been reported to police by an animal welfare group, according to Norwegian broadcaster NRK.
The incident occurred at the Rundereimstranda site near Stad following delousing operations, after which fish began dying in large numbers over a period of weeks. In some cages, mortality approached 50%. Fish were reported to have severe gill damage and oxygen deficiency.
The regulator conducted an inspection as the site was being harvested and identified a harmful algal bloom as the primary cause of the health issues. It took approximately five weeks to fully harvest the site.
Following the event, the authority decided not to proceed with a document-based review of the case. It has since described the incident as “very serious,” but confirmed that no direct enforcement action was taken, instead incorporating the findings into a broader audit of the company.
The NGO Dyrevernalliansen has now filed a police complaint, alleging that the company breached animal welfare legislation by not slaughtering the fish earlier. Norwegian law requires farmed fish to be culled when necessary to prevent suffering, with the same legal protections as terrestrial livestock.
Mowi said it had slaughtered the fish “as quickly as possible” under the circumstances, noting that algal events are rare but can significantly impact fish welfare due to gill damage. The company added that such events are outside its control but must be managed as effectively as possible, and said it will await the outcome of any police review.
The mortality event began in week 33, with partial harvesting initiated in week 35 and the remaining cages cleared by week 37.
While Mowi described algal blooms as rare, the regulator said such events occur relatively frequently in western and southern Norway, although the scale of the impact in this case was unusual. Total mortality in Norwegian salmon farming reached 54.9 million fish last year, equivalent to 14.9% of production.
Police confirmed receipt of the complaint and said they will assess whether to open an investigation, but noted limited capacity in environmental crime units may delay any decision.