Infectious diseases, main cause of salmon mortality in first 4 months of 2024

During the first four months of 2024, infectious diseases have been the main cause of salmon mortality, according to the Norwegian Veterinary Institute.

These conclusions have been reached thanks to the collaboration of the various companies that have shared information about dead fish. These figures were collected in the AquaCloud database.

In more detail, infectious diseases accounted for nearly half (46%) of the mortality in the first four months of the year, while injuries accounted for 22%, and environmental conditions for 10%. Additionally, winter ulcers are the most significant recorded infectious disease during this period.

On the contrary, infectious diseases were less significant in January, and according to the institute, the main cause of mortality in this month was environmental conditions, especially in the northernmost production areas. Therefore, jellyfish account for nearly all mortality attributed to the environmental conditions category in January.

As a summary, Torfinn Moldal, Head of Fish Health at the Norwegian Veterinary Institute indicated: "Given the challenges many sites faced with jellyfish before Christmas, it is not surprising that jellyfish have also caused mortality in the new year. Winter ulcers and handling injuries are also known causes of mortality."

Professional bodies like Tekna are calling on the Norwegian government to implement tighter regulations on salmon producers as they consider there are "no clear rules".

Data collector process

According to the Directorate of Fisheries, the companies that participated in the project account for about half of the biomass in the sea. Their participation is completely voluntary.

The causes of mortality are divided into main categories and subcategories. This system provides a sample at the national level and in different geographic areas.

However, the institute warns that a complete picture of disease prevalence and other causes of mortality is not possible. Updates to the records may involve minor changes that do not affect the overall conclusions.

The three major diseases affecting farmed salmon and trout in Norway

The Norwegian Veterinary Institute just published a report that focuses on three major diseases affecting farmed salmon and trout in Norway: pancreatic disease (PD), bacterial kidney disease (BKD), and infectious salmon anemia (ISA).

While pancreatic disease has declined, bacterial kidney disease has seen a resurgence of outbreaks, which pose a significant risk to both farmed and wild fish.

The fact that pancreatic disease has decreased, and that this seems to be a continuous trend, means some experts have viewed it as "very positive".