"Put preventive measures in place if there are any, and ensure good preparedness. Farmers must be quick to implement measures if they experience an attack by pearl moths," said Bård Skjelstad, director of the Norwegian Food Safety Authority’s aquaculture division.
Photo: Norwegian Food Safety Authority
The Norwegian Food Safety Authority (Mattilsynet) has reported a surge in string jellyfish in Norway's coastal waters in recent days, which has led to extensive fish deaths across multiple fish farming facilities.
The national authority, which includes oversight of aquaculture in Norway, has released a news announcement urging fish farmers to heighten their preparedness, implement preventive measures, and be ready to act swiftly to reduce suffering and manage outbreaks.
String jellyfish, also known as "pearl-chain" jellyfish or "Perlesnormanet," can float into net pens, causing sever injuries to salmon, including skin and gill burns. The injuries, combined with stress, can exacerbate other health conditions in the fish, causing further welfare issues, the Authority states.
Bård Skjelstad, director of the Norwegian Food Safety Authority’s aquaculture division, emphasized the responsibility farmers have to protect their fish from prolonged suffering.
“The primary duty of animal owners in this situation is to prevent long-term suffering,” Skjelstad noted, urging producers to implement prompt preventive actions and maintain a state of readiness.
Skjelstad also stressed that farmers should not wait for official directives if they notice extensive damage among their fish. Fish with significant injuries should be promptly removed and humanely euthanized. In cases where removing individual fish is unfeasible, farmers may need to consider culling entire cages to prevent widespread suffering, Skjelstad said.
In response to the reported incidents, the Norwegian Food Safety Authority has issued specific guidelines to help farmers manage outbreaks, including regular and systematic monitoring of fish welfare in affected cages to assess the scope of damage.
The Authority also advises that producers should be prepared with adequate slaughter capacity to handle affected fish quickly, and utilize appropriate recording and handling measures for dead and injured fish, aligned with the facility’s size and fish population.
Reflecting on last year’s winter season, which reached unprecedented levels of fish mortality partly due to jellyfish blooms, Skjelstad emphasized the need to avoid a similar outcome this year. Farmers are thus urged to adopt proactive measures to protect fish welfare through the coming months.
"It is not acceptable to enter a new winter where almost half of the fish that are slaughtered have open wounds, as was the case last year," Skjelstad said.