Fish health and welfare have never been more under the spotlight, especially in Norway where the government aims to become a global leader in animal welfare. The Norwegian government has set ambitious targets to reduce salmon mortality to 5% by 2035. In 2024, the average mortality rate was 15.4%, a slight improvement from 16.7% in 2023. However, the Norwegian Fish Health Report documented that 57.8 million salmon died in the seawater phase in 2024, with around one-third of these deaths attributed to handling stressors and damages from delousing treatments.

In 2024, sea lice levels peaked at +30% higher than the previous five years due to record sea-surface temperatures, leading to 3160 non-medicated treatments. The financial costs associated with sea lice are significant, including direct treatment costs and downstream impacts. Additionally, Norway's traffic light system restricts production increases based on lice impact on wild smolts, limiting industry growth.

Optimized nutrition and functional feeds have great potential to improve fish health and are widely adopted in preventative healthcare strategies. Phytogenics, a category of feed additives, can bring numerous benefits when used correctly. A recent trial at Stirling University tested a unique blend of essential oils (Digestarom? PEP MGE Aqua) to evaluate its anti-parasite effects against sea lice (Lepeophtheirus salmonis). Atlantic salmon were supplemented with these diets for six weeks before a sea lice challenge was applied.

The results showed a statistically significant dose-dependent response, with lower numbers of lice attached to fish in the higher two doses, corresponding to a reduction of approximately 60%. This highlights the importance of dosage and opens up possibilities for reducing the need for delousing treatments in salmon cages. These findings could significantly improve fish health and welfare while saving costs associated with treatments.