Sinister secrets from the lagoon: Are critics of fish farming just food snobs? Or is aquaculture bad for the fish and its environment? Joanna Blythman investigates

Rick Stein became suspicious about the provenance of some of the fish delivered to his restaurant when he noticed that the sea bass was all the same size. Wild sea bass normally vary greatly, and chefs generally favour the larger ones, which can be cut into good, thick fillets.

'This bass looked slightly different, too. It was darker than usual, the flesh was soft and flabby, and the flavour was boring,' says Mr Stein, who runs the Seafood Restaurant at Padstow in Cornwall.

So he quizzed the supplier, a fish merchant in Plymouth, who admitted that the fish had been farmed 'somewhere near Calais'.

'I was extremely irritated when I found out, because no one had made any attempt to tell us that the fish was farmed. And I wouldn't be in the least bit surprised if lots of restaurants are using it and keeping quiet.'

Mr Stein's sea bass probably came from one of the saltwater lagoons, such as the Ile de Re, on the west coast of France. Thanks to developments in modern aquaculture, these are now being used to farm fish that were previously only available from the wild (for example, bass, bream and turbot). The farming of these species has become big business in France. Other countries, including Italy, Spain, Tunisia, Israel and even Chile, are also in on the act.

Until recently, only two species of fish, rainbow trout and salmon, have been farmed in quantity. In neither case has the farming been a great success. Farmed rainbow trout is widely regarded as a water-exuding, flaccid travesty of what was once a fine, athletic fish. And despite the wide availability and price advantage of farmed salmon, chefs and food-lovers prefer wild salmon or sea trout.

Industry experts (and make no mistake, fish farming is an industry) put such reactions down to snobbery and prejudice, and say objective comparisons between wild and farmed fish are rare and generally inconclusive. But earlier this year, the French consumer magazine Que Choisir (equivalent to Which?) conducted the largest and most comprehensive analysis and blind tasting to date of farmed and wild fish. The results revealed an ocean of difference between the two types.

Laboratory researchers first compared wild and farmed bream, bass and turbot. They found that the farmed fish were much more fatty than their wild equivalents, with farmed bass almost 10 times higher in fatty lipids. This is persuasive evidence of how fish farming could actually transform species once considered lean into fatty fish akin to mackerel and herring.

All samples had been sourced through one of Paris's top fishmongers, La Poissonnerie du Dome. The blind tasting of minimally cooked fish took place at a leading restaurant, La Cagouille, where the wild fish did twice as well as those that were farmed.

On smell, tasters noted a stronger odour from farmed fish, which was 'more like silt from the seabed rather than the smell of the sea'. On texture, they found that the wild fish had firmer flesh, but was juicy in the mouth. The farmed specimens were wetter to start with, but then became drier in the mouth.

But flavour was where the results were most remarkable. 'While the wild fish varied in taste according to what we were sampling, we got the impression that the farmed ones all had a similar taste, and even the professionals among us were unable to identify the species by their characteristic aromas. The feeding of farmed fish must play a major role in this. In aquacultures, all species have a similar diet,' Fabienne Maleysson, a taster says.

Unfortunately on the day of the tasting there were storms at sea, so no wild salmon was available. Two samples of farmed salmon were therefore tested: one French, one Scottish, and the Scottish sample was much better received than the French.

How a wild salmon would have compared remains a matter of conjecture; but, according to Mr Stein, farmed salmon never matches wild. 'The worst stuff tastes very earthy, the better stuff is rather dull and hard to describe, while wild salmon has a sweet, fresh, nutty quality that you never get in farmed varieties.' But, however superior wild fish are, their flabbier and fattier farmed relatives may yet see them out of the market place. These days, it is a rare and excellent fishmonger who still offers shoppers the choice of wild or farmed fish. Wild salmon usually sells for about twice the price of farmed (though there are times when it becomes more competitive), and it is not available all year round. Such coming and going is annoying to supermarket buyers and fish wholesalers, who favour a steady source at a guaranteed, stable price.

Advocates of aquaculture regard farming as the democratisation of the king of fish; the ability to transform a seasonal luxury into cheapish protein for the masses. But for food lovers, this sort of fish is about as appealing as the year- round, tasteless strawberry.

Environmentalists, too, view the ascendancy of farmed fish as nothing short of disastrous. Ever since salmon farming started in Scottish lochs, there have been complaints about pollution from effluent, the use of colourings to make the fish pink, and the effects of toxic chemicals used to kill the sea lice, which fish kept in cages attract. In 1990, residues of antibiotics and the toxic chemical Dichlorvos were found in samples of fresh salmon on sale, proof that these pollutants find their way into our food.

Since the mid-Eighties, there has been an alarming decline in the numbers of wild salmon and sea trout. And it is thought that sea lice, spreading from the fish farms, have caused the downturn in stocks. In Loch Maree, for example, local residents are campaigning for more restrictions on fish farming. In the mid-Eighties, 2,100 sea trout a year were taken out of the loch by fly fishermen. Last year the catch was a mere 339.

Animal welfare activists have joined environmentalists in their battle with fish farmers. Compassion in World Farming says that intensive fish farming is unacceptable. According to a spokesman, Philip Lymbery, 'farming of salmon and trout means that free, living animals from the wild are crowded and confined, thwarting many of their natural behaviour patterns in order to provide an unnecessary luxury food at a great cost to the environment'.

As aquaculture casts its net even wider to include species such as bass, bream and turbot, the dilemma for the concerned consumer intensifies. There is a question of labelling. How are we to know whether what is being offered is wild or farmed, since there appears to be no legal obligation on retailers or wholesalers to state the provenance of a fish?

For consumers, the knowledge that fish is wild is essential information, not just as an indicator of eating quality, but also as a minimum environmental and welfare guarantee.

(Photograph omitted)