Report warns of poor fish welfare and environmental risks in Norwegian aquaculture
High mortality rates, sea lice infestations, and environmental impacts continue to pose significant challenges to fish welfare and sustainability in Norwegian aquaculture, according to a new risk assessment from the Norwegian Institute of Marine Research.
The “Risk Report Norwegian Aquaculture 2025” highlights several ongoing issues that could have severe consequences for the industry.
The report underscores that 60 million farmed salmon were recorded as dead or discarded in 2024, down from 65 million the previous year. The reduction is attributed in part to a less severe outbreak of pearl oyster jellyfish. Nevertheless, mortality rates remain elevated, particularly in six production zones where the risk to fish welfare is categorized as high.
The spread of sea lice intensified in 2024, exacerbated by a marine heatwave that increased infection pressure on wild salmonid populations. Production areas PO8, PO9, PO11, and PO12 saw an increased risk classification from low to moderate for sea lice-induced mortality among migrating salmon post-smolts. Additionally, sea trout and sea char populations in several zones experienced heightened exposure to lice infestations.
While the proportion of escaped farmed salmon in rivers continues to decline, certain production areas remain vulnerable to genetic mixing between wild and farmed fish. The risk classification was revised downward in PO4, PO11, and PO12 but was increased to a high level in PO9 due to monitoring gaps. Notable escape incidents in 2024 and early 2025 included a 27,000-fish escape in PO10 and a 15,000-fish escape in PO5.
The report also examines the environmental consequences of aquaculture waste, copper-based antifouling agents, and the use of wild-caught wrasse in fish farms. While the use of copper has declined by 82% since 2019, the impact of replacement substances such as tralopyril remains insufficiently studied. The authors emphasize the need for further research on the long-term ecological effects of aquaculture-related pollutants.
Climate change continues to compound these challenges. The marine heatwave of 2024 has underscored the uncertainty surrounding future environmental conditions and their impact on aquaculture. The report warns that knowledge gaps persist in understanding how marine ecosystems will respond to sustained warming and increased fish farming activity.
Despite these concerns, Norwegian aquaculture remains a key economic sector, accounting for 74% of Norway’s total seafood export value in 2024. However, maintaining its global reputation will require addressing these persistent welfare and environmental risks.
