Half of the seafood consumed by most country is farmed. Fish farming, also known as aquaculture, is the fastest-growing food animal sector, outpacing the beef and poultry industries. While wild fish find their own food -- which includes smaller fish for carnivorous species -- intensively farmed fish are fed a manufactured aquaculture feed. 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, so the industry has shifted the makeup of the feed.
Jillian Fry, PhD, a faculty member at the Bloomberg School says "Our review found that increasing plant-based ingredients can change the fatty acid content in farmed fish, which can affect human nutrition."
The new study details the industry shift to crop-based feed ingredients, such as soy, corn, and wheat, to replace wild fish as a key ingredient in manufactured feed. The researchers -- in collaboration with colleagues from the University of Minnesota's Institute on the Environment and McGill University -- reviewed aquaculture and public health literature, and conducted a new analysis to estimate the environmental footprint for the top five crops used in commercial aquaculture feed.
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 as well.
Using vegetable oils instead of fish oil changes the fatty acid content of fish and nutritional value for human consumption, the researchers say. Considering Americans are encouraged to consume seafood high in omega-3 fatty acids, which promote improved cardiovascular health and neurodevelopment, this has large implications for dietary recommendations and the aquaculture industry. More research is needed, they say, to better understand the impact of this shift in feed
on the health benefits of consuming farmed fish.