A change in how farmers are raising seafood is expected to affect human nutrition, a new study found.
According to the research team from the Johns Hopkins Center for a Livable Future (CLF) at the Johns Hopkins Bloomberg School of Public Health, the University of Minnesota's Institute on the Environment and McGill University, there has been a global shift in the type of feed that is being used in fish farming.
The team explained that prior to this shift, farm-raised seafood ate feed made from fish meal and fish oil, which came from wild fish. However, since catching wild fish to use as feed was no longer sustainable, farmers have been relying on plant-based options, such as soybean meal. The researchers noted in 2008, aquaculture feed contained 50 percent more soybean meal than fish meal. They estimated that from 2008 to 2020, the use of plant-based ingredients can increase by 124 percent.
This change in ingredients appears to be altering the fat content in the fish, which can then affect the amount of nutrition that people are getting from eating these sources. The researchers reported that vegetable oil-fed fish had "lower relative fractions of omega-3s" and higher relative fractions of monounsaturated fatty acids (MUFA), omega-6 polyunsaturated fatty acids (PUFA) and overall PUFA, which include omega-3 and omega-6, in comparison to the fish oil-fed fish.
"Farmed fish get their health-promoting omega-3 fatty acids, EPA [eicosapentaenoic acid] and DHA [docosahexaenoic acid], from their feed, and specifically from fish oil," study leader Jillian Fry, director of CLF's Public Health and Sustainable Aquaculture Project, said. "Our review found that increasing plant-based ingredients can change the fatty acid content in farmed fish, which can affect human nutrition."
The researchers added that since omega-3 fatty acids contribute to heart health and positive brain development, current dietary guidelines might have to be adjusted once researchers know more about the nutritional differences between farm raised seafood and seafood that is caught in the wild.
"The nutritional content of farmed fish should be monitored," Fry said. "The aquaculture industry should assess the environmental footprint and public health impacts of their crop-based feed ingredients and seek those produced using sustainable methods."
The findings were published in the journal Environmental International.