The UN wildlife trade body slapped down bids on Tuesday to regulate cross-border commerce for two species of sharks threatened with extinction through overfishing, sparking anger from conservationists. Millions of scalloped hammerhead and oceanic whitetip sharks are extracted from seas each year, mainly to satisfy a burgeoning appetite for sharkfin soup, a prestige food in Chinese communities around the world. The 175-nation Convention on the International Trade in Endangered Species (CITES), meeting in Doha, rejected the US-sponsored proposals but only by a narrow margin, opening the possibility that one or both could get a second hearing on Thursday when the 13-day conference ends. Only decades ago, the two species were among the most common of the semi-coastal and open-water sharks. But bycatch, or fish caught accidentally, and demand for fins has slashed hammerhead populations by about 80 percent globally, and by up to 90 percent in the Indian and Pacific oceans, experts say. Many of the fish are tossed back into the water after their precious fins have been removed. The whitetip, found in all the world's oceans, is listed by the International Union for the Conservation of Nature (IUCN) as 'critically endangered' in the northwestern Atlantic, and 'vulnerable' globally. Once the highest level of biomass in the Gulf of Mexico, the species is 99 percent depleted there today, according to marine biologist Julia Baum. China spoke against the hammerhead proposal in plenary session, saying that even their well-trained fisheries officials had been unable to distinguish between fins once they were cut off. 'Our experience has shown that control of these species at the borders would not be enforceable,' a Chinese delegate said. Japan led opposition to both measures, arguing that management of shark populations should be left to regional fisheries groups, not CITES. Conservationists counter that fishing for sharks is currently unregulated. 'The problem today is not there is serious mismanagement of trade in sharks, as for tuna, but that there is no management at all,' said Sue Lieberman, policy director for the Washington-based Pew Environment Group. They also point out that sharks are especially vulnerable to overfishing because most species take years to mature and have relatively few young. Initially, four other 'look-alike' species were also to be covered in the two US proposals, to prevent accidental harvesting. But the US withdrew two of the species -- the dusky and sandbar sharks -- whose fins resemble the scalloped hammerhead's, retaining only the smooth and great hammerhead. The proposals called for listing on CITES' Appendix II, which requires countries to monitor and report all exports, and to demonstrate that fishing is done in a sustainable manner. The bids was supported by the UN Food and Agriculture Organisation, as well as the secretariat of CITES, which makes recommendations on all measures. Conservation groups reacted angrily to the votes. 'We see clearly now the Japanese motivation for opposing all these marine species proposals,' said Anne Schroeer, an Madrid-based economist with Oceana. 'For the whales they say we are catching it traditionally. For the bluefin tuna, they say we are eating it. But for the sharks, there is nothing but pure economic interest.' In a vote on bluefin tuna last week, the CITES meeting voted down a proposal for Appendix I status, which imposes a total ban on cross-border trade. The fight over bluefin pitted commercial interests against conservationists, and the result suggests it was a mismatched fight. In the case of sharks, there is business on both sides of the issue: dozens of small island nations, and some bigger ones, reap serious revenue from scuba- related tourism. Two other sparks species -- the porbeagle and spiny dogfish -- were set to come up for Appendix II listing votes later on Tuesday. All told, a third of the world's 64 species of pelagic, or open water, sharks face extinction, according to report issued last June by the IUCN's Shark Specialist Group. 