The shocking thing about the FSA's findings is not the deception itself - there's clearly money to be made from passing cheaper fish off as its more expensive wild cousin. But rather that established major retailers, including Asda, Sainsbury's and Harrods, have been implicated.
Fraud is a strong word, and the FSA's report has sent the industry into a frenzy of rebuttal. After all, if its conclusion that some 15% of farmed fish is sold as wild is even half accurate, consumers have overpaid for fish to the tune of millions of pounds. Salmon is the main species of fish eaten in this country. We also got through more than 4,000 tonnes of sea bass and 1,700 tonnes of sea bream in Britain last year, and seafood sales are leaping across the board.
So what is going on? Can consumers trust that the fish they are buying comes from where the retailers say it does?
On the whole, yes they can, says John Adams at the Federation of Fishmongers. However, he points the finger of blame at wholesalers rather than retailers. "Fishmongers are not necessarily getting good information from their wholesalers," he says. "If we buy from Peterhead and they tell us it has come from north of the Shetlands, we have to assume it is."
Another industry insider also blames suppliers. "In a packaged product, the label is going on wrongly at the processors," he says.
Yet the retailers are not entirely beyond reproach and many wholesalers say it would be impossible to sell a retailer or fishmonger a farmed salmon as wild because of their very different appearances.
"In farmed salmon the fat lines are very broad because they have lived a sedentary life in a cage eating a diet high in oil and fats," says Bruce Sandison, who has campaigned for years against Scotland's fish farming industry. "A wild fish will have swum thousands of miles - so its fat lines are very thin." Wild salmon can be almost purple. Farmed is pink.
Sea bass and bream, meanwhile, tend to be smaller from farms than from the wild.
Another obvious pointer is the time of year: it's just not possible to buy wild Scottish salmon, for example, outside the fishing season, which runs from mid-February to mid-October.
The retailers themselves dismiss that there is a problem. Sainsbury's has voiced the strongest criticism of the FSA's report. A spokeswoman claims the findings amount to no more than allegations and says it is totally unfounded. Asda, which was found to be selling farmed sea bass as wild at its Gloucester store, points out it hasn't listed wild bass for years. Waitrose, meanwhile, which wasn't implicated, talked up its traceability measures.
The FSA is confident it got its facts straight. "The method used in this survey is just one of the novel food authenticity methods that we are developing," says head of food authenticity Mark Woolfe. "We hope that the survey and availability of the method will deter any future fish food fraud."
However, Woolfe admits that human error may have been at play. "Once a fish is filleted, it is more difficult to tell whether it is farmed or wild. The mistake could easily have happened further down the line."
This view is supported by others in the industry. "On a fish counter, the label is just a wee thing stuck into the fish and an error by staff will have been responsible," claims one industry player.
This has been Harrods' defence. A spokesman says: "On the day the sample in question was purchased, human error may have been responsible for farmed and wild salmon (which are sold adjacent to each other) being mixed up. Revised stock control measures have subsequently been implemented to avoid a reoccurrence of the problem."
The FSA has also played down the relevance of the survey, which only involved 26 out of more than 250 local authorities, and says the results are not representative of all wild fish on sale.
It isn't taking any chances, though. It has opened its sampling methodology and findings to retailers in a bid to ensure they get their act together. It is also launching a guide for smaller retailers explaining the rules governing fish labelling.
The FSA is clear that legislation is in place to protect the consumers and that retailers are acting responsibly. But more can be done. "We don't need any more legislation, it is already a very highly regulated industry," says Woolfe. "What we need is for retailers large and small to understand what is required of them. nthe fsa's findings
Fifteen out of 128 samples of 'wild' fish and fish products bought in shops and wholesalers were actually farmed, the FSA's recently published survey found. Another 11 products were "not consistent with wild".
The majority of the mislabelling cases were on salmon - Britain's most popular fish. The survey discovered that 15% of salmon samples, 11% of sea bream and 10% of sea bass labelled as wild were from farmed sources. Sainsbury's, Asda and Harrods were named for this, while samples from Tesco, Morrisons and Waitrose produced results outside the FSA's database, meaning that no conclusions could be drawn.
In a second element of the survey, the FSA looked at whether products complied with the EU's labelling rules on showing the production method and catch area of a product. It found that 57 of 387 (15%) samples of fish and fish products from wholesalers and retailers across the UK either provided no information or did not meet legislative requirements.
Of the 57 cases, 43 occurred in smaller businesses such as fishmongers, but retailers including Morrisons, M&S, Tesco and Aldi also had labelling problems.
The survey took place during October 2005 to January 2006, and June to August 2006. The results are not representative of all wild fish on sale, says the FSA.