The price of caviar has trebled over the past 15 years: sturgeon’s roe now costs about £140 per 50g jar, reinforcing, as if it was necessary, its long association with the rich and the decadent.

It is also grim proof of the simple economics of supply and demand. The sturgeon is struggling in the wild, caviar is, therefore, in desperately short supply and that has pushed the price up — and up.

Indeed, so concerned is the Convention for International Trade of Endangered Species (CITES) with the over-fishing of wild sturgeon that it has issued no fishing licences this year. Any wild caviar on the market is last year’s stock (although there is a thriving black market).

Yet caviar was not always a luxury commodity. One hundred years ago rivers and seas were stuffed with sturgeon, even in Britain, and everybody could eat it, if they wanted to. Sergei Trachook wants us to return to those heady days. According to the Russian, who owns a fish farm near Riga in Latvia: “One day our rivers will be teeming again.”

Since 1998, international trade in sturgeon species has been regulated by CITES because of concerns over the impact of unsustainable harvesting in wild sturgeon. The situation in the Caspian Sea, where most of the world’s caviar is produced, became dire after the break-up of the Soviet Union, which led to the virtual collapse of management and control systems.

Mr Trachook is trying to turn the tide by producing sustainable caviar. He doesn’t kill his sturgeon, like most other caviar producers. Instead, he “milks” them for their roe, using ultrasound technology and massage, before swiftly returning them, unharmed, into temperature-controlled tanks.

CITES has given his fish farm Mottra the thumbs up. It sees the business as a way forward in preserving the sturgeon, which is near to extinction. Mr Trachook has already started to deposit young fish into the nearby Daugava River in the hope that they will start to breed again.

Mr Trachook is selling his farmed caviar for half the price of wild caviar. A 50g jar of farmed Mottra osetra costs about £70 in Selfridges in London, compared with £140 for the same amount of wild caviar. Once he opens more fish farms, he will be able to bring that price down still further.

Mr Trachook founded Mottra in 2002, together with his countryman Sergei Reviakin, who is based in London. They bred all the 50 tons of sturgeon — both osetra and sterlet — that they have from eggs, but it has taken until now to start harvesting them, as they waited patiently for the fish to mature — four years for some, eighteen years for the most highly prized sturgeon, beluga.

They are not alone in pursuing an eco-friendly approach to caviar, but they are, argues Mr Reviakin, different from their rivals. “Our way is very labour intensive,” he says. “You need three people just to harvest the roe.”

This is how: in Mottra’s spotlessly clean “delivery room” three robed staff, complete with masks, gloves and hair nets, wheel in a 3ft osetra sturgeon lying surprisingly still, a thin orange cloth covering its head to keep it calm. One uses ultrasound to detect the position of the roe inside, then another begins to massage out the roe in long, sweeping movements through the fish’s urinogenital opening, where a two-millimetre cut has been made to loosen the muscle — “It’s more comfortable for the fish,” Mr Reviakin says. The roe shoots out in a jet of black liquid into a waiting plastic bowl. The whole process takes less than two minutes.

Other farmed caviar producers also harvest sturgeon roe this way, but many make a larger, caesarean-style incision, which must be sewn up afterwards, limiting the number of times that the fish can be “milked”.

Mottra claims that its approach means that sturgeon can live out their natural lives (wild sturgeon are rumoured to live up to 200 years), spawning again and again, with 18 months or so between each milking.

The key to the system? Mottra points to its temperature-controlled cement tanks, with a unique waterpurifying system, which mimic the sturgeon’s natural habitat as closely as possible.

Already top chefs are taking note. Richard Corrigan has put it on the menu of his Mayfair restaurant, Corrigan’s, impressed as much by its clean flavour as by its green credentials.

But its Russian producers are looking beyond the wealthy enclaves of London. “I would like to see caviar sold in supermarkets,” Mr Trachook says. He and his partner appear to be heading in the right direction.

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