Taking a closer look at the sustainable seafood industry, researchers from the Gordon and Betty Moore Foundation’s Marine Science Initiative found that many fish farms stock their tanks with juvenile fish caught in the open ocean, whereas wild-caught fisheries often seed their waters with farmed hatchlings, complicating consumer labeling and conservation efforts.
Wild-caught seafood is commonly touted as healthier than farmed fish because it is thought to be free of contaminants from the farming process. Aquaculture fisheries, such as those for bluefin tuna, on the other hand, are generally thought of as more sustainable alternatives to wild-caught fish. However, many fish farmers seed their stocks with smaller, wild-caught fish. "Both aquaculture and fisheries managers often overlook the environmental impacts of stocking aquaculture operations with wild-caught individuals," the authors wrote. Conversely, fishermen of wild-caught salmon are known to add farmed hatchlings to their runs, to boost yields.
Such hybrid practices have made calculating the environmental impact of each fishing classification difficult. "Adding a new hybrid category to national and international seafood production record keeping would easily make these data available to global analysts, with little extra effort required by individual countries," Dane Klinger, a researcher involved in the study, told ScienceInsider.