Jessica McConnell, 26, of Silver Spring, Md., tries to identify halibut, red snapper and salmon at a dinner hosted by Oceana and the National Aquarium in Washington, D.C. Heather Rousseau/NPR hide caption

itoggle caption Heather Rousseau/NPR

Thierry Chopin from the University of New Brunswick examines a raft that holds strings of seaweed. The seaweed grows around pens of farmed salmon and soaks up some of the nutrients that would otherwise pollute the Bay of Fundy. Richard Harris/NPR hide caption

itoggle caption Richard Harris/NPR

A young parishioner carries plates filled with fried fish and potatoes to a table during a Lenten Friday fish fry at St. Frances Cabrini Catholic Church in Littleton, Colo., in 2009. David Zalubowski/AP hide caption

itoggle caption David Zalubowski/AP

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