Grieg Seafood ASA harvested approximately 8,200 tonnes gutted weight (GWT) in the first quarter of 2026, according to a trading update published by the company.
The company said elevated sea lice pressure and reduced survival rates followed a period of high seawater temperatures during the second half of 2025. In response, Grieg Seafood initiated mechanical delousing treatment during that period.
Those treatments coincided with an unexpected period of prolonged cold seawater temperatures during the first quarter of 2026.
The combination of warm summer conditions, mechanical sea lice treatment and the subsequent cold period affected the quality of harvested fish. The share of superior-quality fish dropped to around 60 percent, resulting in lower price realization alongside higher harvest volumes and elevated farming costs.
Grieg Seafood estimates the total EBIT impact for 2026 at NOK 50–75 million (€4.50–€6.75 million). The majority of the impact is expected to be recognised in the first quarter of 2026, with only limited effects anticipated for the remainder of the year.
The company said the mechanical treatment involved has now been discontinued as part of measures implemented to prevent similar situations in the future. Most fish currently in the sea and planned for harvest in 2026 have not been subjected to the treatment.
Grieg Seafood added that the incident is not considered representative of the historical performance of its Rogaland operations and is largely viewed as a one-off event. The average number of treatments per post-smolt group remains below one, including the increased treatment activity during the period.
An extended trading update for the first quarter of 2026 is expected to be published around 21 May, the company said.