Sharks are being slaughtered at an unsustainable rate, with a new study showing 100 million are killed a year.
Before the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites) begins meeting today in Bangkok, the authors of the study, published in the journal Marine Policy, warn that the rate of fishing for sharks, most of which grow slowly and reproduce late in life, is exceeding their ability to recover.
"Sharks simply can't keep up with the current rate of exploitation and demand," said Boris Worm, a marine biologist at Dalhousie University in Halifax, Canada. He said protective measures "must be scaled up significantly" to avoid further depletion and the possible extinction of many species of shark in our lifetime.
Sharks are caught for meat, liver oil, cartilage - and especially their fins.
Several nations have banned shark finning but the researchers found no drop in the numbers of dead sharks, many of which are dumped at sea after their fins have been hacked off.
"Their numbers are crashing," said Elizabeth Wilson of the Pew Global Shark Conservation campaign. "We are now the predators."
Conservation charities including World Wildlife Fund are lobbying hard for this Cites meeting, the first since 2010, to take decisive action on the illicit wildlife trade, with rhinos and elephants also under threat. The British Border Force's specialist Cites team finds illegal items "every day".
Recent seizures include a box of ivory bracelets, a stuffed snow leopard and four rhino horns worth more than £1 million ($1.8 million). Officer Tim Luffman says shark fin and medicines made from tiger are common finds.
Ivory, worth about £1000 a kg, has been outpriced by rhino horn at £40,000 to £60,000 a kg on the black market. Border Force officials are also finding rare orchids, endangered live fish, and coral and birds of prey.
Proposals to protect sharks, which failed in the face of Asian opposition in 2010, will be considered before the meeting ends on March 14.