Global talks on the conservation of endangered species have rejected calls to ban international trade in bluefin tuna, raising new fears for the future of dwindling stocks.

Countries at the meeting of the Convention on International Trade in Endangered Species (Cites) in Qatar voted down a proposal from Monaco to grant the fish stronger protection. The plan drew little support, with developing countries joining Japan in opposing a measure they feared would hit fishing economies.

It is understood that the UK, the Netherlands and possibly other European nations voted in favour of the Monaco proposal, against the EU's official position.

Campaigners complained that debate on the fate of the Atlantic bluefin fishery was cut short and an immediate vote pushed through by Libya. Seventy-two out of 129 Cites members voted against the trade ban and 43 voted in favour, with 14 abstentions.

Dr Sergi Tudela, head of fisheries at WWF Mediterranean, said: "After overwhelming scientific justification and growing political support in past months, with backing from the majority of catch quota holders on both sides of the Atlantic, it is scandalous that governments did not even get the chance to engage in meaningful debate about the international trade ban proposal for Atlantic bluefin tuna."

The UK environment secretary, Hilary Benn, said: "As we have long argued, bluefin tuna must be afforded protection if we are to avoid losing it forever. Today the UK has shown its commitment to bluefin tuna. We are disappointed that proposals to list bluefin tuna on appendix I of Cites were defeated."

Monaco introduced the proposal because it said only extreme measures can save stocks of the iconic migratory fish, which have fallen by 75% due to widespread overfishing. Only the United States, Norway and Kenya supported the proposal outright. The European Union asked that implementation be delayed until May 2011 to give authorities time to respond to concerns about overfishing. It's official position was to abstain in the vote on the Monaco proposal.

Japan, which imports 80% of Atlantic bluefin and had led the opposition to the ban, restated its position that Cites should not regulate tuna and other marine species. It said it would accept lower quotas for bluefin tuna, but said they should come from the International Commission for the Conservation of Atlantic Tunas (ICCAT), which currently regulates the trade.

"Japan is very much concerned about the status of Atlantic bluefin tuna and has been working so hard for many years to ensure recovery," said Masanori Miyahara, of the Fisheries Agency of Japan. "But our position is very simple. Let us do this job in ICCAT, not in Cites. This position is shared by majority of Asian nations."

Tudela said: "ICCAT has so far failed miserably in this duty so every pressure at the highest level must come to bear to ensure it does what it should. It is now more important than ever for people to do what the politicians failed to do, to stop consuming bluefin tuna."

WWF said it would step up calls for restaurants, retailers, chefs and consumers around the world to stop selling, serving, buying and eating the endangered fish.

Monaco had said its proposal would not mean a permanent ban and that trade could resume once stocks recovered.

"This exploitation is no longer exploitation by traditional fishing people to meet regional needs," Monaco's Patrick Van Klaveren told delegates. "Industrial fishing of species is having a severe effect on numbers of this species and its capacity to recover. We are facing a real ecosystem collapse."

The tuna defeat came hours after delegates rejected a US proposal for a Cites ban on the international sale of polar bear skins and parts. The US argued that the sale of polar bears skins was compounding the loss of the animals' sea ice habitat due to climate change. There are projections that numbers of the bears, which are estimated at 20,000 to 25,000, could decline by two-thirds by 2050 because of habitat loss in the Arctic.

"We're disappointed," said Jane Lyder, the Department of Interior's deputy assistant secretary for fish and wildlife and parks. "But we understand that Cites is still trying to understand how to incorporate climate change into its decision-making."

Canada, along with Norway and Greenland, led the opposition to the US proposal. They said the threat from trade was minimal and the hunting carried out by indigenous people was critical to their economies. Only 2% of Canadian polar bears are internationally traded and the country strictly manages the commerce, Canada said.