A large portion of the seafood consumed in North America is farmed. But the food those fish eat increasingly includes more crop-based ingredients, like corn, soy, and wheat.
Until recently, this manufactured feed was typically composed of high levels of fishmeal and fish oil derived from wild fish—but it has become unsustainable to catch more wild fish to feed growing numbers of farmed fish.
The shift has been hailed by some as a positive change in light of the increasingly depleted oceans and the rapidly expanding aquaculture industry. But the shift may have some unintended consequences, experts say.
“Farmed fish get their health-promoting omega-3 fatty acids, EPA and DHA, from their feed, and specifically from fish oil,” says study leader Jillian Fry, a faculty member at Johns Hopkins Bloomberg School of Public Health. “Our review found that increasing plant-based ingredients can change the fatty acid content in farmed fish, which can affect human nutrition.”