This is the true story of the salmon scare which threatened last weekend to bring British salmon farming to its knees. It is a sorry saga of flawed science, selective research and hidden commercial bias. That it was allowed into the pages of the apparently respectable journal Science is inexplicable. Its worldwide promotion by an organisation with a vested interest in undermining farmed Atlantic salmon in favour of the wild Alaskan variety is a scandal. Its central claim, that farmed Atlantic salmon have higher levels of pollutants than wild ones, is simply unproven, since the report itself concedes that it never actually examined wild Atlantic salmon. That a British expert could nevertheless describe the report as “definitive” is dumbfounding.

The report hit the headlines on Friday with a vengeance. Based on a worldwide survey of salmon bought in supermarkets in March 2002, it said that fish raised in Britain and other Northern European countries were so contaminated with carcinogenic chemicals that consumers would be unwise to eat them more than six times a year. It said that their chemical levels broke guidelines set by the US Environmental Protection Agency and greatly outweighed any of the health advantages associated with eating fish. It had the immediate effect of stalling salmon sales and threatening the already fragile fish farming industry in Scotland.

Here are the facts: the survey was conducted by the Institute for Health and the Environment at the State University of New York at Albany, whose scientists are respected and respectable. It was financed, however, by the immensely wealthy, Philadelphia-based Pew Charitable Trusts, which campaigns actively on global pollution, and which believes in direct intervention against industries that it regards as hostile to the environment. Pew challenges logging companies and air polluters, all legitimate targets, but it has also succeeded in shutting down the long-line fishing industry in the Pacific, in order to protect sea turtles, has curtailed the fishing of Alaskan pollock, which was said to threaten sea lions, and has now turned its sights on Atlantic farmed salmon. According to The New York Times: “With its deep pockets and aggressive political advocacy, Pew is not only the most important new player, but the most controversial” on the environmental scene.

David Carpenter, one of the scientists who conducted the research, was remarkably frank about his funders. While insisting that his own work was purely scientific, he said of the Pew Charitable Trusts: “There may be some legitimacy in saying the reason they chose to fund this study was that they had another agenda well beyond the health effects.” His interview, published on the IntraFish website, is worth reading, as are the details of the way the fish were bought. It emerges that salmon were purchased in Britain before new labelling laws, requiring their source to be identified, were introduced. Thus there was no absolute guarantee that they were wild or farmed. Dr Carpenter confessed he was “unaware” that wild salmon were still on sale in Europe. “If we had been able to get wild Atlantic salmon we would have tested them,” he said.

Both Pew, and the David Suzuki Foundation, a Canadian environmental organisation which campaigns on behalf of Alaskan wild salmon fishing, immediately published the results of the institute’s survey on their websites, with approving headlines. This was not just another Science report, to be picked up or not by sharp-eyed correspondents. It was put out around the world in a press release from the international PR organisation, Gavin Anderson, which confirmed that its client was the institute itself, but refused to say where the funding had come from.

So there we have it. Instead of an independent study from an internationally accepted source, this was a survey with a clearly defined political agenda, funded by a powerful organisation which would be delighted to see fish farms closed down altogether. That is the kind of thing I would like to have known before I read the headlines. And so, I imagine, would the British consumer.