Farmed salmon nutritional value declines due to dietary shifts

Research led by the United States Department of Agriculture indicates that the omega-3 fatty acid levels in farmed salmon have declined significantly over time. This nutritional shift is attributed to changes in aquaculture feeding practices. While salmon are naturally carnivorous, the industry has transitioned from using marine-based oils to land-based crops such as soy and canola to sustain explosive production growth.

In Norway, the world’s largest salmon producer, marine-based feed ingredients dropped from 90 percent in 1990 to approximately 23 percent in 2020. This shift has raised environmental concerns, as some research suggests the use of crop-based ingredients has doubled greenhouse gas emissions per kilogram of farmed fish in Europe and the United Kingdom between 2000 and 2020. Additionally, advocacy groups have noted that soy used in Norwegian salmon feed is often linked to deforestation in the Amazon.

While the USDA and American Heart Association continue to recommend fish consumption for heart health, experts warn that current dietary guidelines may rely on outdated nutritional data regarding the omega-3 content of pen-raised fish. The aquaculture industry continues to expand to meet global demand, though critics argue the benefits are disproportionately directed toward wealthy nations.