The humphead wrasse provides some of Hong Kong's most expensive fish dishes, which, in a city with a strong tradition of luxury dining, is saying something. Caught on a Pacific coral reef and airfreighted alive to a restaurant tank in the Chinese city for special occasion dinners, its flesh can fetch as much as $175 - and that's US dollars - (£97) per kilogramme.

The humphead wrasse provides some of Hong Kong's most expensive fish dishes, which, in a city with a strong tradition of luxury dining, is saying something. Caught on a Pacific coral reef and airfreighted alive to a restaurant tank in the Chinese city for special occasion dinners, its flesh can fetch as much as $175 - and that's US dollars - (£97) per kilogramme.

But the such is the growing demand that wild populations of the humphead, which full-grown can reach 190kg, are in now in freefall. At an international conference next month, Britain will back a proposal for the trade to be regulated for the first time.

At the Bangkok meeting of the Convention of International Trade in Endangered Species (Cites), the UK will join the rest of the EU in calling for the humphead, Cheilinus undulatus, to be listed on the Cites Appendix II, which means that trade in the fish will have to be monitored everywhere.

The proposal is thought necessary because intense demand, fuelled by high restaurant prices, and ironically, by its own increasing scarcity, is now wiping out the fish on many Pacific reefs.

The situation is exacerbated by two factors. First, the fishing method often used is cyanide poisoning. This only stuns the humpheads but can have a devastating effect on other fish and on the coral. Second, the most prized fish are small ones - so that diners can have a whole fish on the plate - and this means that young fish are mostly being caught. Thus the wrasse population decline is hastened.

"We now believe that the time is right for listing this species as a textbook example of how Cites can intervene effectively to ensure sustainable use of a species which is vulnerable to over-exploitation," said Elliot Morley, the Environment minister, who will be representing Britain at the conference.

Mr Morley will also be backing a proposal from Australlia and Madagascar for the great white shark of Jaws fame to be given a similar Cites listing. Targeted fishing, accidental catches, and, more particularly, specialised trophy hunting, are rapidly reducing the numbers of a magnificent) creature.

The UK is backing a proposal for the Irrawaddy dolphin, which inhabits the coasts and rivers of northern Australasia and southern Asia, to be listed on Cites Appendix I, meaning that all trade in the species is banned, and will firmly resist a proposal from Japan for the northern hemisphere stocks of minke whales to be "downlisted" from Appendix I to Appendix II - which would mean that trade in whale products could resume.