Campaigners for the environment are calling for the closure of a fish farm used by Jamie Oliver to promote the quality of Sainsbury's salmon. They claim it causes widespread pollution.
Divers from the Salmon Farm Protest Group say new photographs from the bottom of Loch Hourn in the Scottish Highlands show a barren landscape more like the moon than a healthy marine environment.
Officials from the Scottish Environment Protection Agency (SEPA) confirmed yesterday that the site failed to meet environmental standards and the operators had been sent an official warning.
The fish farm, run by the international aquaculture company Marine Harvest, was featured in a television advert for Sainsbury's in which Jamie Oliver - who admits to only serving fresh wild salmon in his own restaurant - praised the quality of the caged salmon it produces. He was even shown plucking a fish out of the loch and dashing off to cook it.
Environmentalists say the water is heavily contaminated and this is responsible for the demise of life on the floor of the sea loch. "The seabed under the farm is dead," said Bruce Sandison of the protest group. "There has been a salmon farm on the loch for about 15 or 20 years and coupled with the fact that there is a slow tidal change of water at the site the pollution has built up to devastating effect."
Many of the problems have been caused by the accumulation of a sewage fungus called beggiatoa which forms slimy, furry growths on the seabed and then smothers everything in its path as it reduces oxygen levels in the water. Although the fungus can occur naturally, campaigners say the abundance of waste from the farm has wiped out almost every other form of life around the cages.
"There was no life, the whole area was inert," said Graeme Bruce, who led the dive team. "On the seabed we could see a litter of white shells, all that remained of the creatures that once lived there. I have not seen a reef so devoid of life. The reef looked just like the lunar landscape I had been so captivated by as I watched Neil Armstrong and Buzz Aldrin 'moon walk' on the television when I was six!" Apart from a couple of crabs, he found no life apart from large patches of beggiatoa which "stretched as if trying to smother everything in its path".
SEPA said the site was inspected regularly and although it was complying with conditions relating to biomass, medicine usage and cage numbers, recent seabed surveys had shown "some evidence of unsatisfactory impacts".
"Present monitoring shows a degree of environmental impact at the site, significant enough to fail SEPA environmental standards," said a spokesman. "Continuing evidence of such unsatisfactory impacts may lead to SEPA taking further steps, [such as] a reduction in the biomass of fish which is permitted to be held at the site."
Mr Sandison said: "The fish spend their entire lives swimming around in their own sewage and that is what is killing everything else at the bottom of the loch. If people going to supermarkets were aware of that would they continue to buy it? SEPA has a policy to protect the environment. Rather than negotiating with the company to limit the damage they should close it down and stop the pollution completely."
Marine Harvest, which has previously been fined £500 for overstocking its cages, was unavailable for comment. But a company spokesman was reported as saying: "All salmon farms inevitably have some impact on the seabed, but this has been minimised by innovations such as the introduction of mechanised feeding systems which ensure that little or no fish feed falls to the seabed."