Escolar, right, is often substituted for more expensive Albacore tuna (left), a report on mislabeled seafood found. Yoon S. Byun/Boston Globe via Getty Images hide caption

itoggle caption Yoon S. Byun/Boston Globe via Getty Images

Swordfish from Canada are marked with a label from the Marine Stewardship Council at a Whole Foods in Washington, D.C. The MSC says its label means the fish were caught by a sustainable fishery, but critics says it's not always so clear. Margot Williams/NPR hide caption

itoggle caption Margot Williams/NPR