Mitsubishi-backed salmon group Cermaq lost 20 percent of the fish in one of its cages on Oct. 14 following a delousing incident in Hellarvika, Norway.

About 20 to 30 minutes after a transition on the boat, stressful behavior of the fish was observed, Cermaq told the Norwegian Food Safety Authority at the time.

"The mortality continued during and immediately after unloading, but stopped afterwards," Cermaq said.

In the end, over 24,000 salmon died, which corresponds to around 20 percent of the fish in the cage.