A tuna fishing boat drags a cage of nets on the Mediterranean sea in 2010. (The Mediterranean is not considered to be part of the "high seas.") Andreas Solaro/AFP/Getty Images hide caption

itoggle caption Andreas Solaro/AFP/Getty Images

A marlin caught as bycatch by the California drift gillnet fishery. The conservation group Oceana called the fishery one of the "dirtiest" in the U.S. because of its high rate of discarded fish and other marine animals. Courtesy of NOAA hide caption

itoggle caption Courtesy of NOAA

Beware of the big guys: Red snappers from tropical waters sometimes accumulate high levels of the toxin that causes ciguatera. Go for the smaller fish to avoid it. Kamel Adjenef/iStockphoto hide caption

itoggle caption Kamel Adjenef/iStockphoto

A sperm whale entangled in a drift net. A report says commercial fisheries around the world kill or injure 650,000 mammals a year. Alberto Romero/Marine Photobank hide caption

itoggle caption Alberto Romero/Marine Photobank

With local cod so scarce, Chef Toby Hill of Lyric Restaurant in Yarmouth Port, Mass., tries out a dogfish salad — served here with garlic aioli on toast — instead. Dogfish is still plentiful in New England waters, but wholesale fisheries say there's not much demand for it in the U.S. Christine Hochkeppel/Courtesy of Cape Cod Times hide caption

itoggle caption Christine Hochkeppel/Courtesy of Cape Cod Times

"A lot of people are eating seafood all the time, and fish are eating plastic all the time, so I think that's a problem," says a marine toxicologist. iStockphoto hide caption

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How to make dead fish look attractive? That's the challenge New York-based duo Shimon and Tammar Rothstein faced when they were hired to do the photography for famed French chef Eric Ripert's book On the Line. Photos by Shimon and Tammar, Courtesy of Shimon and Tammar hide caption

itoggle caption Photos by Shimon and Tammar, Courtesy of Shimon and Tammar

Based on new research, the EPA concludes that women of childbearing age are making more informed choices and opting for low-mercury seafood choices such as shrimp, canned light tuna and salmon. JackF/iStockphoto hide caption

itoggle caption JackF/iStockphoto

Sea urchins are considered a culinary delicacy, but supply can't keep up with demand. Aizat Faiz/Flickr hide caption

itoggle caption Aizat Faiz/Flickr

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

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

Farmed Atlantic salmon was sometimes labeled at "wild salmon," researchers found when the tested seafood sold in New York City. iStockphoto.com hide caption

itoggle caption iStockphoto.com

A Tokyo sushi restaurant displays blocks of fat meat tuna cut out from a 269kg bluefin tuna. Yoshikazu Tsuno/AFP/Getty Images hide caption

itoggle caption Yoshikazu Tsuno/AFP/Getty Images

An oyster shucker on Samish Island, Wash. on Puget Sound. The state is frequently forced to close beaches to oyster gatherers because of the risks of harmful algae blooms. Ted S. Warren/AP hide caption

itoggle caption Ted S. Warren/AP