The US is taking action to shut down the illegal trade in Beluga caviar - at £80 an ounce (28g) probably the world's most expensive food - because the fish that produces it is heading for extinction.
Since the US takes 80% of the output, the ban on sales offers the first real hope that the beluga sturgeon species, estimated to date back 250m years, can be saved. The EU market, the second largest, has shrunk because of the high price.
The US fish and wildlife service (FWS), has been considering the ban for many months, in effect listing it under the US Endangered Species Act, on grounds that uncontrolled poaching by gangs has rendered any quota system for catches worthless.
To allow negotiations to take place on how any legal trade can be maintained, the ban will not come into effect for six months. Under the convention on international trade in endangered species the countries around the Black Sea have got a small official quota for selling caviar.
Beluga, known as black gold, has been a money spinner for Azerbaijan, Iran, Kazakhstan and Russia.
Although Iran has virtually stopped the trade to try to save the fish, critics believe the other countries have deliberately overestimated surviving stocks so as to avoid a ban on international trade. Their estimate of beluga numbers appeared to show an increase from 7.6 million in 1998 to 11.6 million in 2002. This is despite the fact that numbers of belugas caught have been plummeting for 30 years.
"Unregulated overfishing, loss of spawning habitat, and poaching to supply the black market beluga caviar trade, have all contributed to a notable decrease in the wild beluga sturgeon population," Steve Williams, service director of the FWS, said yesterday.
There are three main species of sturgeon in the Caspian. The beluga, the largest and the most valuable, has been raised in farms since the original spawning rivers were dammed in the Soviet era. The other species are also down in numbers but not so dramatically.
The beluga, Huso huso, which can live for 100 years and does not spawn until it is 15 or 16, has already disappeared from the Adriatic and is rare in the Black Sea. It is believed to be at around 10% of its former numbers in the Caspian Sea.
Historically, some fish have measured six metres (19ft) in length, weighed a tonne, and produced more than 100kg (220lb) of roe. But Beluga sturgeon are normally between 75kg and 100kg and those being taken in the current commercial harvest are much smaller than the giants of previous years.
The FWS acted after a campaign called Caviar Emptor took it to court. The legal trade in beluga is worth £60m but the illegal trade is worth up to £600m.
In 2000 14.9 tonnes was imported by the US, 1.8 tonnes by Germany, 0.9 tonnes by France and 1.2 tonnes by Switzerland for distribution through retailers, including those in Britain.