Lice measures are insufficient, warns fish farms watchdog
Many areas are experiencing infection pressure that makes handling challenging, says Aud Skrudland, acting department head at the Norwegian Food Safety Authority
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The Norwegian Food Safety Authority (Mattilsynet), has observed that several areas with high levels of aquaculture along Norway's coast have developed high levels of infection with sea lice, reports Fish Farming Expert's Norwegian sister site, Kyst.no. According to Aud Skrudland, acting head of the marine department in the aquaculture inspection division, this creates a vicious circle.
"We see that in several areas with dense farming, infection pressure is building up, which makes it very demanding to deal with sea lice. Frequent treatments increase the strain on the fish and the risk of poor welfare," she says.
She emphasises that Mattilsynet does not have a detailed overview of which methods the individual facilities use at any given time, but considers that the current capacity and measures are not sufficient to meet the regulatory requirements.
"In general, we consider that the preventive measures that are being implemented, and the capacity that is available for processing and slaughtering, are not sufficient to comply with the regulatory requirements," says Skrudland.
High level of resistance
On behalf of Mattilsynet, the Norwegian Veterinary Institute is conducting surveillance of resistance to treatment agents. The latest report – The surveillance programme for resistance in salmon lice ( Lepeophtheirus salmonis ) in Norway 2023 – shows that the level of resistance to most of the salmon lice agents tested remained high in 2023.
"The level was stable or slightly increasing," summarises Skrudland.
The Norwegian Veterinary Institute further reports that freshwater treatment appears to result in lower lice mortality at moderate salinities the more times the facility has been treated for lice in the past two years. The effect was most evident at a salinity of seven parts per thousand.
Increased supervision and auditing in 2025
Mattilsynet points out that sea lice are still one of the biggest challenges for both fish health and fish welfare. According to Skrudland, the supervisory authorities have a special focus this year on proper treatment and correct reporting.
"The main goal of the inspection is to verify that treatment against sea lice is carried out in a responsible manner and safeguards the fish's functional capacity and quality of life," she says.
Among the measures that have been prioritised in 2025 are:
- Closer dialogue with the industry to clarify requirements for processing and regulations.
- Several unannounced inspections to check that reported lice numbers are correct and that treatments are carried out properly.
- Follow-up of serious incidents in connection with delousing.
- Audit of fish farming companies' internal systems for planning and implementing delousing, as well as actors who operate delousing units.
"Treatment against sea lice is a major burden for farmed salmon. Frequent treatments increase the risk of injury and disease. Injury after delousing is one of the main reasons why farmed fish die and have poor welfare," says Skrudland.
Mattilsynet also points out that it has invited the industry to participate in a new regulatory sandbox for digitalisation and development in aquaculture, which will look at opportunities for more modern follow-up and supervision. The application deadline to participate expired on October 10.
Record number of adult female lice in PO6
The Institute of Marine Research's latest report on lakselus.no shows that there are large regional differences in the lice situation in week 42 (October 13-19, 2025). In production area 6 – from Nordhordland to Stadt – the number of produced lice larvae and adult female lice is above the level from 2024, and at a record high level for the last four years.
The water temperature in the area has been slightly above the average for the past 13 years, which contributes to more lice that develop quicker. The models also show dense spread of infection between several facilities, with high export of sea lice larvae within the same infection network.
Higher lice production has also been registered in production areas 3 and 4 than last year, while areas further north – including PO 7 and 8 – are close to or below last year's level.
The figures illustrate a persistently high infection pressure in parts of Western Norway, where milder temperatures and high biomass have contributed to increased production of louse larvae throughout the autumn.
