Grieg Seafood cut its 2026 harvest forecast from 31,000 to 29,000 tonnes on Friday, October 2, after an algae event caused gill damage and elevated mortality at one farming site during September.
In its market announcement, the company put biomass losses from the event at an estimated 1,000 tonnes, using information available at the time.
Grieg Seafood also raised its full-year farming-cost guidance from NOK67.5 ($7.02) to NOK71 ($7.38) per kilogram.
“The increase in farming cost primarily reflects the reduced harvest volume and the financial impact associated with the mortality event,” the company said.
Grieg Seafood said biological conditions at sea had been strong throughout August before the unexpected algae event caused a deterioration at the affected site. Mortality rose gradually throughout September.
The company kept the situation under close observation and is taking steps to limit the effects, including temporarily suspending harvest. This suspension is reflected in the revised full-year harvest guidance.
Grieg Seafood says production in 2027 will be unaffected by the mortality event. It is continuing its review of the event's operational and financial effects and plans to share more information as part of its regular financial reporting.
The company had lowered its 2026 harvest guidance from 31,000 to 30,000 tonnes in May. It subsequently raised the forecast back to 31,000 tonnes in August, when it reported its first-half results.
The August increase reflected stronger freshwater output despite challenges in seawater production during the first half.