Fishing threatens a third of ocean sharks worldwide

A third of all sharks on the high seas are threatened with extinction because they are overfished or killed incidentally in swordfish and tuna catches, a nature group warned Thursday.

The International Union for Conservation of Nature, the producer of the world's Red List of endangered species, released its shark study ahead of a meeting in Spain of tuna fishery managers. The gathering includes those responsible for fisheries "in which sharks are taken without limit," IUCN said.

"Despite mounting threats, sharks remain virtually unprotected on the high seas," said Sonja Fordham, a shark specialist for the group. "The vulnerability and lengthy migrations of most open ocean sharks call for co-ordinated, international conservation plans."

The great and scalloped hammerhead sharks and the giant devil ray are globally endangered, IUCN said. The basking and oceanic whitetip sharks, two mako species and three thrashers join the iconic great white shark as globally vulnerable to extinction.

IUCN said ocean sharks were often only incidental bycatch as fishermen sought tuna and swordfish. But new markets for shark meat, especially the fins used in Asian soups, are driving demand.

The worst approach in the fisheries industry has been "finning," which is when the fins are cut off and the rest of the shark's body is dumped back in the sea, IUCN said. The practice has been banned in most international waters, but the rules are poorly enforced, it said.

Sharks take many years to mature and have few offspring, making them particularly sensitive to overfishing, IUCN said.