ISA subsides in Norway, but two additional pancreatic disease outbreaks confirmed

Pancreatic disease has been detected at farming sites operated by Mowi and its subsidiary Nova Sea in Norway.

Pancreatic disease (PD) can cause lower growth in farmed salmon as they lose hunger and become more susceptible to other diseases, often leading to death.

Mowi’s 10447 Mefaldskjæret and 31857 Blomsøråsa sites in Alstahaug municipality in Nordland county were confirmed to have incidences of pancreatic disease by the Norwegian Food Safety Authority on 20 November. Nine days later, on 29 November, Nova Sea notified the regulator of a suspected outbreak of the disease at its 18936 Igerøy Ø site off Igerøy island in central Norway.

Mowi’s sites, which are close to the LetSea site affected by pancreatic disease in September 2023, were culled after the confirmation of the presence of the disease by the Norwegian Food Safety Authority, and the Nova Sea site will also be cleared out if the authority confirms the company’s detection of the virus there to reduce the spread of infection. Nova Sea reported 4,500 metric tons of biomass present in the 10 net-pens at the site.

“The Norwegian Food Safety Authority takes the PD detection seriously. It is a highly contagious salmon disease that leads to poor health and welfare for the fish, and to great losses for the industry,” Norwegian Food Safety Authority Northern Regional Director Geir Arne Ystmark said.

A 30-kilometer-wide area around the impacted zone – north of Trøndelag’s Skjemta and Flatanger municipalities – have been declared a control zone, limiting movement through the region. The Norwegian aquaculture authority will be conducting extended sampling in the affected area until it is confident the disease has been cleared.

“Everyone who travels in the area or carries out activities related to fish farming must show the necessary care so that the risk of the spread of disease is reduced,” Ystmark said. “The Norwegian Food Safety Authority will shortly assess whether there is a need to extend the existing restriction zone.”

Currently, there are 61 farms listed on the Barents Watch tracking page, which is operated by the authority, as having known or suspected pancreatic disease issues. However, just two sites are listed as being impacted by infectious salmon anemia (ISA), which cropped up to a greater degree in 2023 than previous years.

On 11 November, the authority lifted a protection zone put in place around the 45127 Hellerflesa site in Trøndelag’s Nærøysund municipality, where ISA was detected in June 2023. In October, it phased out a protection zone around 33797 Hidlekjerringa in Rogaland’s Strand municipality, where ISA was discovered in June 2023, and lightened restrictions around a number of sites in Vestland where ISA was first detected in July 2023.

Photo courtesy of Nova Sea