More farmed salmon have wounds and injuries than in previous years: "Significant deterioration"
Since 2023, there has been a significant deterioration in the number of fish that are sorted out, according to a researcher.
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When farmed salmon are slaughtered, they are mainly sorted as either superior or production fish.
Superior is the best fish, meaning the healthiest and free of defects.
Production fish have wounds, injuries, or deformities that prevent them from being sold as superior. Instead, they become salmon fillets, salmon cakes, salmon burgers, and other fish products.
"A common factor for a large proportion of the fish downgraded to production fish is that they had reduced animal welfare before being slaughtered," says Torfinn Moldal, a researcher at the Norwegian Veterinary Institute.
He participated in the launch of the Fish Health Report 2024 on Tuesday, March 11.
In 2024, 80.6 per cent of the fish were classified as superior.
"This is the lowest number since 2017 and a significant deterioration since 2023," says Moldal.
"Roughly speaking, this means that every fifth salmon slaughtered is downgraded," he says.
Salmon lice weaken the fish
The main reason for the downgrading of salmon is wounds and injuries, which are primarily caused by treatment against salmon lice.
According to the report, salmon lice remain the biggest challenge for Norwegian fish farming. The parasite feeds on the fish's mucus, skin, and blood. While the lice themselves are a nuisance, the treatments used to remove them are even more harmful to the salmon.
The treatment either involves placing the fish in hot water to kill the lice, which also causes the fish severe pain, or it is brushed or sprayed to remove the lice. The latter damages the salmon's skin, causing small cuts and wounds.
These wounds can become infected with bacteria, further weakening the fish and leaving visible damage. As a result, the fish is downgraded to production quality at slaughter.
Slightly lower mortality rates
Slightly fewer farmed salmon died last year compared to the previous year, with a decline of just over one per cent.
"This is a positive sign," State Secretary Even Sagebakken from the Ministry of Trade, Industry and Fisheries said during the launch of the 2024 Fish Health Report.
"But we are all probably aware that this is a long-term challenge, and we have a long way to go," he said.
Despite this improvement, the report highlights serious health and welfare issues in Norwegian salmon farming.
The average mortality rate for farmed salmon is now 15.4 per cent, which is much higher than the government's target of five per cent (link in Norwegian).
Infectious diseases and injuries following lice treatment were the main causes of mortality in Norwegian farmed salmon.
"Injuries from lice treatments, wound issues, and gill disease are the biggest challenges. However, we're seeing a positive development for several viral diseases," acting department director Ingunn Sommerset tells the Norwegian News Agency NTB.
Points to weaknesses
It is the employees at the slaughterhouses who report the number of production fish and superior fish to the Norwegian Food Safety Authority.
The figures in the Fish Health Report are based on these slaughter reports, but researchers highlight several weaknesses in the system.
'While these reports provide a general overview of the status of slaughtered farmed fish over the past year, the quality of the information depends on the accuracy of the reported data,' the report states.
For example, there are inconsistencies in how employees apply different classifications, and some reports lack the total number of fish.
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Translated by Alette Bjordal Gjellesvik
Read the Norwegian version of this article on forskning.no
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