Norwegian Institute of Marine Research trial with 52,000 juvenile salmon: PD virus from farms poses limited threat to wild salmon populations

Researchers at the Norwegian Institute of Marine Research (HI) used a vaccine program to assess the risk of pancreas disease (PD) spreading from farmed salmon to wild salmon. The trial was announced by the institute on October 28, 2026, and its conclusions point to low risk.

Pancreas disease is a serious viral disease that can cause high mortality, reduced growth rates and lower slaughter quality in aquaculture. HI's new trial shows that outbreaks in the salmon farming industry are not enough to raise concern about increased mortality among wild salmon.

"At least not at levels that affect populations," marine researcher Abdullah Sami Madhun said in the institute's press release.

The large research project, led by Madhun, was conducted at the mouths of the Etneelva and Daleelva rivers in Vestland county, where researchers released a total of 52,000 juvenile salmon. Of these, 28,000 were vaccinated against PD, while the other 24,000 were left unvaccinated as a control group.

The juvenile salmon were all offspring of wild salmon but were hatched and reared in facilities by the researchers, and all were implanted with chip tags before being released into the rivers. When they returned to the rivers as adults, the researchers recorded them.

Some fish were captured so that researchers could record their length, weight and sex, and collect internal organ samples for further analysis.

"During the trial period, several pancreas disease outbreaks occurred at farming facilities along the migration route. Nevertheless, we observed no difference between vaccinated and unvaccinated fish, either in survival at sea or in growth. This supports the conclusions of previous studies that the virus is rarely detected in migrating wild salmon," Madhun said.

The trial concluded that the PD virus is unlikely to pose a threat to wild salmon populations.