Citing overfishing, scientists added several species of deep sea sharks on Thursday to the World Conservation Union's (IUCN) endangered Red List.
At a meeting in Oxford, England, the scientists listed all three species of thresher sharks — known for their scythe-like tails — as "vulnerable globally," and moved the shortfin mako to "vulnerable today" from "near threatened".
"The qualities of pelagic sharks — fast, powerful, wide-ranging — too often lead to a misperception that they are resilient to fishing pressure," said Sarah Fowler of the IUCN's Shark Specialist Group.
"This week, leading shark scientists from around the world highlighted the vulnerability of these species to overfishing and concluded that several species are now threatened with extinction on a global scale," she added.
Hammerhead species 'endangered'
The scientists decided that the blue shark, the world's most abundant and heavily fished pelagic shark, should remain in the "near threatened" category despite a decline in numbers of 50-70 percent in the North Atlantic and scant conservation measures.
Scientists later added the semi-pelagic scalloped hammerhead shark to the "endangered" category, while the pelagic stingray was put in the "least concern" category, which is still part of the IUCN's Red List.
The Red List categories range from "extinct" to "not evaluated".
Pelagic sharks are taken unintentionally in high seas during swordfish and tuna fishing, and increasingly targeted as new markets develop for their meat and demand grows for their fins.
Demand for shark fins
Bans on shark finning — slicing off a shark's fins — have been adopted for most international waters, but standards of enforcement are low, IUCN said.
"Despite mounting threats and evidence of decline, there are no international catch limits for pelagic sharks," said Sonja Fordham, policy director for the group Shark Alliance.
"The workshop results underscore the urgent need for international fishery commissions to limit fishing for these vulnerable species and strengthen regulations on the wasteful practice of finning," she added.
She said the hammerhead was among the most endangered species from shark finning because their meat had very low value but their fins were highly prized for the Asian delicacy shark-fin soup.