A new study shows that a third of ocean sharks now face extinction A third of the world's open water sharks -- including the great white and hammerhead -- face extinction, according to a major conservation survey.Species hunted on the high seas are particularly at risk, with more than half in danger of dying out, reported the Shark Specialist Group at the International Union for the Conservation of Nature. The report identified the great hammerhead and scalloped hammerhead sharks, as well as giant devil rays, as globally endangered. The smooth hammerhead, great white, basking, and oceanic whitetip sharks are listed as globally vulnerable to extinction, along with two species of makos and three types of threshers. Some 100 million sharks are caught in commercial and sports fishing every year, and several species have declined by more than 80 percent in the past decade alone, according the International Fund for Animal Welfare. The main culprit is overfishing. Sharks are especially vulnerable because they are prized for their meat -- their fins especially, in Asia -- and most species take many years to mature and have relatively few young. The demand for shark fins, a traditional Chinese delicacy thought to convey health benefits, has soared along with income levels in China over the last decade. Shark carcasses are often tossed back into the sea by fishermen after the fins are cut off. Despite bans in international waters, this practice -- known as "finning" -- is largely unregulated, experts say. The most comprehensive survey ever done, this survey studied 64 species of open water, or pelagic, sharks and comes days before an international meeting on high-seas tuna fisheries that could potentially play a role in shark conservation. Significant numbers of sharks have also perished -- including blue and mako -- as "by-catch" in commercial tuna and swordfish operations for decades. The soaring value of shark meat has prompted some of these fisheries to target sharks as a lucrative sideline income, said Sonja Forham, Policy Director for the Shark Alliance, and co-author of the study. "There are currently no restrictions on the number of sharks that these fisheries can harvest," Fordham told AFP by phone. "Despite mounting threats, sharks remain virtually unprotected on the high seas." The IUCN issues the Red List of Threatened Species, the most comprehensive and authoritative conservation inventory of the world's plants and animals species.