The salmon industry in Norway is facing unusual challenges after a harsh winter and a very warm summer due to the El Nino climate phenomenon.

El Nino — a climate pattern raising temperatures across the planet — followed by colder waters and a 20-year high in jellyfish attacks have driven fish mortality to a record 16.7% so far this year, according to Reuters.

Record-high temperatures and warmer waters increase the threat of sea lice.

"Treating sea lice (vaccines) often stresses the fish, posing a threat to its welfare and its resilience to other diseases," DNB analyst Alexander Aukner said.