A woman walks past shark fins displayed in a glass case at a dried seafood shop in Hong Kong. A UN body best known for protecting tigers and elephants is now turning its eye on the world's overfished oceans, considering proposals to regulate the shark trade and ban the export of a tuna species prized by sushi lovers. (Vincent Yu/Associated Press)

Surging demand for shark fin soup among Asia's booming middle classes is driving many species of these big fish to the brink of extinction, a marine conservation group said Tuesday.

Oceana, in a report released Tuesday at a UN endangered species meeting, found that up to 73 million sharks are killed each year, primarily for their fins. As a result, some populations have plummeted by as much as 83 per cent, prompting the 175-nation Convention on International Trade in Endangered Species, or CITES, to consider proposals at its two-week meeting in Doha to regulate the shark trade.

At least eight shark species including the scalloped hammerhead and the oceanic whitetip are being considered for CITES listing, which would put some controls on their export.

"The global shark fin trade is driving the oceans to collapse," Courtney Sakai, a senior campaign director at Oceana, said in a statement. "Trade measures are the most direct way to ensure that the powerful economic incentives to catch sharks do not lead to their extinction."

Shark fin soup has long played central part in traditional Chinese culture, often being served at weddings and banquets. But demand for the soup has surged as increasing numbers of mostly Chinese middle class search for ways to spend their new found wealth.

Oceana estimated that Hong Kong alone imports 10 million kilograms of shark fin each year from as many as 87 countries, with Spain, Singapore and Taiwan being the biggest suppliers. The shark fin industry is also a lucrative one, with a bowl of shark fin soup running as high as $100 US and the fin itself costing $1,300.

Sharks are particularly vulnerable to overexploitation because they generally grow slowly and live long lives. Their relatively low reproductive rates mean their populations are slow to recover once overfished.

Along with sharks, delegates at the UN conference are considering more nearly four dozen proposals on a range of species from rhinos to polar bears. Later this week, they will debate a proposal from Monaco for an all-out ban on the export of Atlantic bluefin tuna, a contentious issue that has the countries of Asia and the West locking horns over a fish prized in sushi.