Bjorn Rothe Knudtsen, Regional Director of Agriculture, noted that these sites have had long-lasting lice problems and that treatments are failing to have satisfactory results.
All farms should remain below a particular level of sea lice to prevent infection on other farms in and wild fish.
Nordmøre has had increasing lice problems in recent years. Resistance to the most important drugs that have been used has contributed to the threat factor.
The FSA stated that in its opinion, Lerøy has failed to meet key regulatory requirements at the four localities, and so now they are receiving notice to halve their production.