Nutritional Decline in Farmed Salmon Linked to Feed Scaling

The rapid scaling of the aquaculture industry may be compromising the nutritional value of one of its primary products. According to reporting from Ars Technica, new research led by USDA scientists indicates that levels of heart-healthy Omega-3 fatty acids in farmed salmon have dropped considerably.

This nutritional decline is attributed to a fundamental shift in diet. To avoid over-exploiting smaller fish species, the industry has transitioned naturally carnivorous salmon to a diet featuring land-based oils and crops, such as canola and soy. In Norway, the world's largest producer of farmed salmon, marine-based feed ingredients fell from 90% in 1990 to approximately 23% by 2020, Ars Technica reports.

While intended to protect marine ecosystems, this shift has created significant terrestrial and climatic pressures. Matthew Hayek, a researcher at New York University, states that soy consumption for all fish farming over the last 20 years resulted in the clearing of forested land equivalent in size to Bangladesh or Nicaragua. Furthermore, Ars Technica notes that research shows greenhouse gas emissions per kilogram of farmed fish in the UK and Europe doubled between 2000 and 2020 due to these crop-based ingredients.

Laura Lee Cascada, director of the Aquaculture Accountability Project, warns that national dietary guidance—including recommendations from the American Heart Association and the USDA—may now be outdated, leaving consumers with a misconception regarding the amount of Omegas they receive. While the USDA declined to comment and researchers noted their sample size was not yet large enough to officially change government advice, the findings highlight a tension between production volume and nutritional output.