Nutritional Decline in Farmed Salmon Questions Industrial Scaling Model

The rapid industrial scaling of aquaculture may be undermining the very nutritional benefits that drove its growth. 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 decay is linked to a fundamental shift in diet. To avoid over-exploiting small fish species, the industry has moved toward land-based oils and crops, including canola and soy. In Norway, the world's largest producer of farmed salmon, marine-based feed ingredients plummeted from 90% in 1990 to approximately 23% by 2020, Ars Technica reports.

While intended to protect marine ecosystems, this shift has created significant terrestrial environmental costs. Matthew Hayek, a researcher at New York University, states that soy consumption for all fish farming over the last two decades resulted in forested land clearing equivalent in size to Bangladesh or Nicaragua. Furthermore, advocacy groups in Norway found that 90% of the soy fed to their farmed salmon comes from three Brazilian companies sourcing from illegally deforested areas of the Amazon rainforest. Other research cited by Ars Technica shows that the move to crop-based ingredients doubled the greenhouse gas emissions per kilogram of farmed fish in the UK and Europe between 2000 and 2020.

Laura Lee Cascada, director of the Aquaculture Accountability Project, argues the industry is trading marine exploitation for land exploitation. She further contends that while the industry claims to feed the world, it is primarily flooding the Global North with unnecessary protein at the expense of the Global South.

Despite these findings, the USDA has not changed its dietary guidelines, which recommend 8 ounces of fish per week. The agency declined interview requests, and the report's authors noted that a more representative study is warranted before official guidance is altered.