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Newspaper Articles

The following is a small selection of the many articles written at the time of the release of Dr. Easton's paper on the contaminant levels in farmed salmon. This research subsequently had a profound effect on the marketing and production of farmed salmon.


Fish First!
Farmed salmon study raises cancer questions
by Frank Fuller

The Anchorage Press. July 26 - August 1, 2001 / Vol. 10, Ed. 30

When almost two million tons of salmon are caught and eaten in the world each year — over half from salmon farms — how can anyone generalize their condition from an analysis of 18 salmon?

These 18 salmon are the center of a controversy that began in England last winter and spread to Canada after two studies found that farm salmon had up to 10 times more polychlorinated biphenyls (PCBs) in their fat than wild salmon.

PCBs are chemical compounds that, although banned in the U.S. since 1979, do not break down easily and remain in the environment indefinitely. When eaten, they are generally stored in fatty tissue, can cause developmental abnormalities and are considered "probable human carcinogens."

Dr. Miriam Jacobs of the University of Surrey in England conducted the first look into farmed salmon in conjunction with the U.S. Environmental Protection Agency. Her study, published last year, analyzed 10 fish from Scottish fish farms and the wild. It found high levels of toxins, including PCBs, in all the fish, but she could not generalize a conclusion from the small number of fish sampled.

Dr. Michael Easton, president of International EcoGen, Inc. in British Columbia, did a second study using eight salmon, both wild and farmed. Easton found that farmed salmon contained up to 10 times more PCBs than wild salmon.

"The results of this study were so compelling that my funder was eager to get the material published," Easton said.

The study, commissioned by the David Suzuki Foundation — an environmental organization that has been highly critical of fish farming — will be published later this year in the journal Chemosphere.

The two studies were featured in a BBC documentary that was later shown on the CBC. The Canadian documentary led to a flurry of newspaper articles and letters to the editor in Europe and Canada. But the issue has been almost completely ignored in U.S. media.

"I think the primary problem is that these studies looked at very small samples, so the results should be characterized as preliminary," said Dr. Rebecca Goldburg, a senior scientist with Environmental Defense who studies food production issues. She did not dismiss the results as aberrations or as incorrect, however, and added that these results demonstrate the need for further, more detailed studies. "It is probably premature to draw sweeping conclusions," she said.

Dr. Easton admitted that the sample size was troublesome. "The only controversial issue might be the sample size," he said. "We used one of the world’s leading labs in determining the level of contaminants. So the analytical chemistry is above reproach. We actually used as many samples as the Canadian food inspection agency uses to determine whether samples of the fish are safe. So the sample size is no different from what the government itself uses."

He added that they are planning another study to look at this issue in more depth.

The president of the B.C. Salmon Farmers Association, however, has been leading the charge against these studies.

"The British documentary takes things up a notch when it asserts that consumers could be exposed to dangerous levels of toxins by eating farm salmon. The basis for this serious accusation is so thin as to be virtually non-existent, but is presented in a manner clearly designed to maximize public alarm," says Anne McMullin, a spokesperson for B.C. Salmon Farmers Association.

McMullin has been critical of the design of Easton’s study. In a letter to the editor of the Vancouver Sun, she wrote that the study has not been peer-reviewed or published and that Dr. Jacobs called claims of high levels of PCBs in farm fish "nonsense."

Those who stand by the studies report that salmon feed seems to be the main culprit behind the contaminated fish. "The European Union last November released a study in which [they] looked at dioxins and PCBs in feedstuff for animals — not just fish, all animals — and the feedstuff that was by far the most contaminated were fishmeal and fish oil, which are constituents of salmon feed," Dr. Goldburg said.

Salmon feed comes from fish high in oil, such as anchovies. Up to three pounds of such fish are needed for farm salmon to gain one pound. PCBs and other pollutants like pesticides and dioxins accumulate in fatty tissue and are passed on to animals that ingest that fat. A predator like salmon accumulates more PCBs in its fat than fish lower in the food chain.

"At least one rationale for believing that farmed salmon could have higher levels of toxins than wild salmon is that they are fed a diet very high in fish oil. The result is a fatty product and potentially one that could be somewhat higher in toxins than wild salmon, which still eat fish but maybe not with the same oil content as farmed salmon."

Adding to this controversy are studies that show farmed salmon to be up to four times fatter than wild salmon, which would enable them to store even more toxins. One, by Dr. Jacobs, will be published soon.

Different health agencies suggest various safety levels for toxins in food, so guidelines differ from country to country. The lowest levels are currently the World Health Organization’s guidelines.

"If we look at levels set recently, like the WHO levels, we discover that you couldn’t even eat one portion of the Scottish farmed salmon a week and not exceed the WHO levels," Dr. Easton said. "In Canada, you shouldn’t eat more than one portion a week of the farmed salmon." The PCBs found in these studies fall below FDA guidelines.

BC salmon farmers, however, insist that fish in general and salmon in particular remain nutritious, and that nutritionists continue to recommend two to three servings of fish a week in a healthy diet.

"Food experts around the world recognize salmon, farmed or wild, as a nutritious source of food protein, with a number of health benefits associated with high levels of omega-3 fatty acids. Regular consumption has been shown to reduce rates of heart disease, stroke, high blood pressure, depression, Alzheimer’s Disease, childhood asthma, among other conditions," she wrote.

Farmed salmon account for about 55 percent of the salmon consumed in the U.S. Most farmed salmon come from Canada and Chile, although European farms are an increasing source.


Toxins, fat content higher in farmed salmon, studies say

Yvonne Zacharias Vancouver Sun - July 21, 2001

That mouth-watering pink salmon you have been throwing on the barbecue on warm summer nights might not be as good for you as you thought.

Two researchers, one local and one in Britain, have been stirring up a storm of controversy with their conclusions that farmed salmon has more concentrated levels of toxins than its natural, wild cousin. Now the British researcher, Miriam Jacobs, a nutritionist at the University of Surrey in Guildford, England, has poured more oil on the fire with new claims that the fat content in farmed salmon is as high as 20 per cent.

Given that British Columbia produces four times as much farmed salmon as the wild type, chances are it's the former you are grilling, particularly if it has the telltale marbled look. With no requirements for labeling, you might never know.

Figures on fat content offered by Canadian authorities vary, but the B.C. Salmon Farmers Association says a three-ounce serving of its members' product contains 11 grams of fat, compared with seven grams in the wild variety. A British authority quoted in the Sunday Times of London placed the fat content of most farmed fish in Britain at around 14 per cent, which is roughly the same as the Canadian farmed salmon which would have a fat content by weight of about 13 per cent.

By comparison, a three-ounce serving of chicken contains eight grams and pork loin 10 grams.

Anne McMullin, executive-director of the salmon farmers' association, pointed out that salmon, including the farmed variety, contains a heart-healthy kind of fat known as Omega-3, but here again, the water gets murky.

McMullin says a three-ounce serving of farmed salmon contains 1.8 grams of Omega-3 fatty acids while an equal portion of the wild variety contains only 1.5 grams. But Christina Burridge, managing director of the B.C. Salmon Marketing Council, says there is some debate over how much of the fat content in farmed salmon is of the Omega-3 variety.

"There is no definitive research on that," she said. "In fact, there is a fair amount of contradictory research."

The fat-content controversy comes as no surprise to Peter Tyedmers. The ecological economist, who has just graduated with his PhD from the University of British Columbia and who now works as a consulting researcher for the university's fish centre, has been studying what is fed to farmed fish.

As a way of increasing profits, he says, the industry has been steadily increasing the amount of fish oil in pellets fed to farmed fish, which are plumped up in cages sunk into the sea. The amount of fishmeal or protein has been steadily decreasing. When the industry started up, the pellets were only between five and nine per cent fish oil; now, they are between 20 and 25 per cent, he said.

Because the local industrial sea fishing industry cannot meet the demand for these pellets, Tyedmers said, much of the supply is coming from the South Pacific, China, Peru and the U.S.

As the fat content increases, so do toxins like polychlorinated byphenyls, pesticides and other chemicals that have been blamed for causing everything from cancer to decreased fertility in humans.

As Tyedmers explained, fat is friendly ground for them.

As another way of reducing costs, the salmon farmers' association admits its producers feed fish an additive called astaxanthin, giving it the tantalizing pink look native to its wild cousin, which gets that healthy glow naturally by eating algae and plankton.

The local stakes in the debate are huge. The industry has grown by leaps and bounds in B.C. since it started up in the mid-1980s and is poised for a major expansion this fall. Last year, farmed salmon was B.C.'s largest agricultural export and 3,400 people were employed in the industry.

This isn't the first time Jacobs has waded into these choppy waters. Nor is she alone. B.C. geneticist Michael Easton, who operates a company in North Vancouver that specializes in studying the genetic impact of contaminants, has also questioned the nutritional safety of farmed salmon in a two-year study partly funded by the ultra-green David Suzuki Foundation. Independently, but almost simultaneously, Jacobs and Easton managed to come up with a comparative snapshot of farmed and wild salmon that is troubling for health-conscious consumers and for the fish-farming industry.

In her initial study, Jacobs looked at 10 Scottish farmed salmon and two wild fish. She found harmful dioxin levels significantly higher in the former variety. So high, in fact, that eating just one 3.5-ounce portion would exceed the weekly maximum acceptable dose of dioxins in Britain.

In his soon-to-be-published study, Easton studied four farmed and four wild salmon. He found the levels of polychlorinated byphenals, pesticides like DDT and other toxic substances in farmed salmon were 10 times higher than the levels in the wild salmon.

The levels are still well within Canadian safety standards, he said in an interview, but come close to exceeding the World Health Organization's recommendation for tolerable daily intake. He noted that the WHO standards were upgraded in 1998 and argues that Health Canada's guidelines are too low.

"Typically, we look at these contaminants at very low levels for their impact because the genetic level of damage occurs are much lower levels than current regulations consider."

The implications of genetic damage are quite significant, he said, adding they include cancer and all sorts of other diseases that are becoming more prevalent. He said he would not eat farmed salmon.

"I consume quite a bit of salmon and it would be foolish to eat salmon that is so close to the WHO tolerable daily intake levels."

Everyone agrees that the small samples don't provide definitive data, but they are hardly comforting and raise enough concern to warrant a closer look.

The B.C. Salmon Marketing Council, with its "go wild" motto, has been promoting wild salmon, but the research is so spotty, Burridge said, it is impossible to claim that wild salmon is nutritionally superior.

"I'm absolutely convinced that wild salmon tastes better than any farmed salmon," she said. "I encourage people to eat wild salmon."

Dietitians in B.C. still recommend two to three servings of fish a week, with no distinction made between wild and farmed varieties, and Canadian Food Inspection Agency spokesman Susan Schenkeveld said tests of both wild and farmed salmon have not turned up evidence of excessive levels of contaminants. The agency hasn't compared levels in the two types.

McMullin was quick to pour water on Jacobs' earlier findings, noting that the researcher herself was upset with the way the British Broadcasting Corporation used her earlier research in a documentary aired last January that caused waves on both sides of the ocean and caused shares in the fish-farming industry in Britain to plummet.

At one point, the BBC, mixing up her findings with those of Easton, falsely attributed to her a statement that farmed salmon contained 10 times more toxic polychlorinated byphenals than wild salmon. The mistake was quickly corrected. In a news release issued by the university, Jacobs maintained, however, that her main point regarding high levels of persistent organic pollutants in farmed salmon was confirmed in both her and Easton's studies.

The nutrition issue joins a litany of environmental concerns over the growing presence of farm-fish cages in the ocean. There are concerns that waste from the farmed fish are creating pools of pollution around the cages and that escaped farmed Atlantic salmon, which have already been spotted by B.C. fishermen, will displace weakened stocks of the wild variety and give rise to new hybrid Frankenfish. Reputable scientists call its accidental release an act of "biological pollution."

They warn that farmed Atlantics will introduce diseases into West Coast waters where native species have no natural immunity and that drugs used to keep farm fish healthy might spawn antibiotic-resistant supergerms in the ocean. McMullin's association couldn't pinpoint the level of antibiotics fed to farmed fish, although it claims the amount is small and that antibiotics are administered only when the health of the fish is threatened.

B.C. commercial fishermen are complaining that the glut of farmed salmon on the market is driving prices so low they no longer cover their costs.

Initially regarded as a huge step down the path of progress at sea, fish farming is a billion-dollar business stretching from Norway to Chile. Over 20 years, world production of farmed salmon has grown from 5,500 tons a year to more than 660,000 tons, according to the World Wildlife Federation. It more than doubled between 1995 and 2000.

In B.C., McMullin said new regulations governing the industry should be in place by September.

"Then we will look at the second stage, which will be growth."

How the King of Fish is being farmed to death

Fish farming has delivered cheap salmon to the consumer - but at a high environmental price. In this in-depth investigation, Stuart Millar talks to farmers, ecologists and scientists about the growing crisis.


Sunday January 7, 2001

A glistening cold winter's day in the Highlands, and Frank Durdle is reminiscing about salmon. For more than 40 years, he has spent a fair amount of his time below the sweeping stone arch of Lovat Bridge in Beauly, near Inverness, pitting his wits against the salmon which battle their way through the pools of the town's eponymous river to their spawning grounds.

Durdle is passionate about salmo salar, the Atlantic salmon: he reveres it as an iconic animal, respects it as a worthy opponent, savours it as a uniquely flavoured meal. 'I can remember as a boy when the fish ran through here in their hundreds,' he says. 'We would stand and watch them leaping out of the water, with the light flashing on their scales. Those were good days. And the taste. There is nothing like it.'

These, too, should be happy times for the president of the Beauly Angling Club. The wild salmon season finished in mid-October, but he no longer needs to wait until the fish start running again in late spring to get salmon on his plate.

Aquaculture - fish farming as it is better known - has heralded an age in which corner shops, let alone the major supermarket chains, are able to have their shelves groaning under the weight of fresh salmon 365 days a year. Good season, bad season, it matters not. But the prospect of year-round salmon fills Durdle with little joy. 'I can't remember the last time I bought farmed salmon and I wouldn't buy it,' he says. 'It is an inferior product and tastes nothing like the real thing. It's all flab and fat, no flavour.' This is not merely the pride of a veteran angler talking.

'Farmed salmon is produced in a completely unnatural way and the industry is causing God knows what damage,' he continues. 'It's high time people realised that being able to buy cheap salmon all year round carries a heavy price in other ways.' For the 21st century consumer, salmon is available in every possible formulation - from whole fish and smoked slices to fillets, steaks, pies and even something called crunchy bites.

Better still, it is cheap yet looks like it came from the same place as its wild relation, with that rich, pink hue. Even the packaging is rustic. Nothing, apart from the bargain-basement price tag, to give away the reality of intensive salmon production, which has turned the King of Fish into the battery chicken of the seas.

But this week, farmed salmon was at the centre of the latest food scare to hit the British consumer. New research, the BBC's Online news service claimed, had found that fish reared intensively in cages contained 10 times the level of cancer-causing toxins as their wild cousins.

The story - taken from a wildlife documentary to be screened on BBC2 tonight - was immediately rubbished, not just by the fish farming industry, but by the Government's Food Standards Agency, and most damningly, the scientist who carried out the research.

Even the Government intervened, with Scottish Office Minister Brian Wilson calling the programme 'wildly inaccurate' and attacking the BBC for what he claimed was 'crass irresponsibility' in its pre-publicity.

He alleged the claims made to publicise the programme amounted to an effort, on the basis of no substantial evidence, to start a food scare and ruin an industry which was of vital importance to many fragile rural communities.

But fish farming is far from squeaky clean, and the safety fears raised in tonight's programme, Warnings from the Wild: the Price of Salmon, are all too real. For more than two decades, the British aquaculture industry has been able to do as it pleased, relying on the fact that the jobs and investment it provided in some of the most remote and poorest parts of the country would discourage Ministers from getting too tough. Now, at last, the game may be up.

Fish farming was an inspirational idea. In the 1960s and 1970s, it was devised as a cottage industry, the new crofting, bringing employment and prosperity to the Highlands and Islands to reverse years of decline. In the sea lochs up the west coast from Argyllshire to Sutherland, in the Western Isles and in Orkney and the Shetlands, the farms began to spring up. By 1980, the output of the Scottish industry was a little more than 800 tonnes. Last year, the 340 farms - 70 per cent of them now owned by hulking multinational corporations such as Norway's Norsk Hydro or the Dutch giant, Marine Harvest - produced 127,000 tonnes of salmon.

Salmon, packed with omega-3 oils, is a rich source of protein. But the growth in output has only been achieved by an increasing intensification of the production process. Yet consumers, who, after repeated food safety scares, would never consider buying a battery-produced chicken, still labour under the misconception that because farmed salmon come from the sea, they are little different from their wild counterparts. Wrong.

Farmed salmon start their lives in a freshwater hatchery. Time is money, and every hi-tech method available is employed to speed up the young salmon's natural growing period. One popular trick is light manipulation. The hatchery tanks are covered over so they are completely dark, then intense lights are shone in to fool the fish into thinking that they are going through their natural growing seasons. Longer periods of light equals summer, shorter periods of light equals winter. 'If people knew all the things we did to make them grow, they would never go near salmon again,' said a former hatchery worker from the Inverness area, who agreed to speak to The Observer on condition of anonymity.

'The only consideration was to get the fish from the hatchery to the market as quickly as possible.'

The salmon go from the hatcheries to the cages, usually situated at the mouths of sea lochs. The cages are vast, up to 70 metres in diameter and some farms are already moving to 90-metre cages. But the fish are packed in tight, with up to 250,000 of them battling for survival space in each one. At these densities, the fish are at the mercy of disease and infestation from parasites.

Sea lice are a naturally occurring parasite found in wild fish. A healthy adult fish would normally carry five or six lice, but in the close confines of the sea cages, the lice are endemic. The fish are unable to swim away into freshwater to get rid of the parasites. The only solution is the use of vaccinations and toxic pesticides, such as pyrethroid chemicals.

'Salmon are farmed in cages at higher densities than battery hens,' says Don Staniford, researcher for Friends of the Earth Scotland. 'They are fed a diet marinated in chemicals and artificial colourings, injected with vaccines and growth promoters, then starved for 10 days before being slaughtered.'

The industry's collective voice, Scottish Quality Salmon, insists that pesticide use is strictly regulated. But there have been worrying signs of farms using illicit substances to control the disease which high density cages make inevitable.

In the summer, Ardessie Salmon, based in Wester Ross, was stripped of its Scottish Quality Salmon membership after The Observer revealed evidence from a former employee of the farm that toxic chemicals were used on a regular basis. A second whistleblower later confirmed the allegations, claiming that the farm had given young salmon deosan deosect to treat lice. The chemical is used to treat horses but becomes deadly when used in aquatic systems. Then, in September, it emerged that a study by the Veterinary Medicines Directorate had found traces of the banned toxic neuroinsecticide Ivermectin in samples of farmed salmon at levels up to four times the legal limit. The residues, found in three of 30 fish tested as part of the VMD's routine surveillance scheme, have sparked an investigation by the Ministry of Agriculture, Fisheries and Food's legal branch and the Scottish Environmental Protection Agency. The owners of the farms involved, which have not been identified, may face prosecution.

The number of medicinal products licensed for use in salmon farms has risen from three in 1989 to 26 last year, with a further 14 under consideration. But even these authorised substances carry serious hazards. 'Most of these treatments are general purpose poisons for dealing with crustaceans,' says Colin Adams, a biologist at Glasgow University.

'The ongrowing cages are open to the environment so to treat the fish for diseases means that the treatment seeps into the environment and can damage the habitats around the cages.'

Yet the cycle of chemical treatment has not prevented disease, which has become more acute as densities and growth rates have increased. In 1998, a new disease, infectious salmon anaemia (ISA), swept through west coast salmon farms. More than 40,000 fish were slaughtered and a quarter of Scottish farms were closed for quarantine. But the measures may have been too late; this year, an escaped farm salmon with ISA was caught in a west coast river, prompting fears it may already have infected wild stocks.

While they are in the sea cages, the fish are fattened up on a diet of pellets made from the rendered remains of small fish that have a high oil content to promote growth. A third of the fish taken from the world's seas are now used to feed other fish. But now questions are being raised about the public health implications of this intensive feeding regime.

As tonight's documentary shows, these small fish are already contaminated with man-made pollutants found in the sea. Toxic chemicals, such as dioxins, a by-product of industrial incineration, and polychlorinated biphenyls (PCBs) which can cause cancer and learning difficulties in children, can be found at low levels in all fish.

The fear now is that by compressing them into pellets to feed other fish, we are magnifying the contamination and allowing it, BSE-style, into the human food chain. A pilot study for Canada's David Suzuki Foundation backed up these concerns: Michael Easton analysed four different types of fish feed and tested four farmed salmon from different sources and four wild Pacific salmon. 'The results were very, very clear,' Dr Easton tells the programme. 'Farmed fish and the feed that they were fed appeared to have a much higher level of contamination with respect to PCBs, organochlorine pesticides and polybrominated diphenyl ethers than did wild fish. In fact, the difference was extremely noticeable.'

The Food Standards Agency contin ues to insist there is no evidence that farmed salmon are more at risk of contamination than wild fish. But in Brussels, the European Commission is already considering how to lower the dioxin and PCB contamination of farmed salmon amid concerns about public health. Two of the EU'S eminent scientific committees have just produced the results of long-running investigations into PCB contamination, both of which back the case for action. The reports will be considered at a meeting in Brussels this month which could lead to tough European-wide action. The report by the Scientific Committee on Animal Nutrition, for example, concludes: 'As farmed fish combines an important consumption of feed materials of fish origin (up to 75 per cent in the diet of carnivorous species) with a high level of contamination of these feed materials, it is the food-producing animal most exposed to dioxins.'

But still Britain refuses to take action. 'The UK government's failure to monitor for dioxins in farmed fish is playing fast and loose with public health,' said Kevin Dunion, director of Friends of the Earth Scotland. 'For every day that they fail to act, public health and the good name of Scottish quality salmon is put at risk.'

The intensive feeding regimes also carry a heavy cost to the environment. In many farms, the fish are fed automatically, and much of the feed will drop straight through the cages to gather on the bottom of the loch along with the ammonium-rich salmon excreta. It is estimated that a 1,000-tonne salmon farm - small by current industry standards - produces sewage waste equivalent to a town of 20,000 people. According to WWF (formerly the Worldwide Fund for Nature), the level of pollution from fish farms on the west coast of Scotland is comparable to the sewage input of up to 9.4 million people.

The resulting mix nutrifies the surrounding waters, destroying delicate marine habitats. More disturbingly, it is also being blamed for spawning the toxic algae blooms which in recent years have closed down 9,000 square miles of west coast shellfish fisheries because the toxins cause amnesiac shellfish poisoning, an irreversible disease that can cause brain damage in humans. 'The siting of salmon farms at the heads of sea lochs is a major problem,' says Adams. 'You need tidal flush to remove the nutrients, diluting them and sweeping them out to sea. But in the deep, glacial lochs around the farm the flushing rate is so poor that it is akin to flushing your toilet once every two weeks.' In some lochs, that figure may be as bad as once every two years.

Additives are also included in the food to give the fish their hue. The most popular is canthaxanthin, which the industry insists is a natural pigment found in flamingos and shrimp. They prefer it because it produces vibrant colours. One pigment manufacturer, the Swiss pharmaceuticals giant Roche, has even produced the Salmofan which opens out into a handy colour chart for salmon, allowing the farmers to choose the colour of their fish in exactly the same way as the rest of us choose the colour of paint for our homes. But there are question marks over the safety of the substance. Some research has found that it can cause deposits of yellow particles on the human retina, with children's eyes thought to be particularly vulnerable. Canthaxanthin is banned for direct human consumption, and sun-tan pills containing it were taken off the market in 1987.

The high-oil content of the farmed fish's diet and their close confinement means they do not develop like wild salmon. The wild creature is pure muscle, honed after swimming thousands of miles. The farmed version is soft and oily because its range is restricted to tiny circles. Because farmed fish contain up to 15 per cent more fat tissue than their wild cousins, it is possible to tell a farmed salmon by the bubbles of oil which run down the knife while it is being sliced.

Some salmon farm proprietors deny that the finished product is any different from the wild fish. Gilpin Bradley is the manager of Wester Ross Salmon, a small operator producing 1,000 tonnes of fish a year at sites near Ullapool on the north west coast. 'We take the natural life cycle of the salmon and we duplicate it in captivity in a way that protects the welfare of the fish,' he says.

'This is a fish which has to lay down a lot of fat in the wild. It has to swim out to sea then it has to come back to spawn. It doesn't eat when it comes back into freshwater so it has to be strong enough to make its way up the river. You find me 10 people who say they prefer wild salmon to farmed salmon. I will cook up some of each and defy them to tell the difference.'

But those who prefer wild salmon may soon find themselves forced to eat the farmed stuff or go without. Perhaps the cruellest irony of the exponential growth in fish farming is that it has come close to driving wild fish, the very creature it was designed to save, to the brink of extinction. Over the past 10 years, wild salmon stocks have declined to all-time lows, but in the north-west Highlands, centre of the aquaculture industry, stocks have been devastated. The cause: infestation of sea lice on wild fish caused by the proximity of caged salmon. In the wild fisheries close to the fish farms, salmon and sea trout have been found with up to 500 lice on them, which cause horrific damage. The lice graze on the flesh of the fish, effectively eating it from the outside in. The Lochy, for example, was once the most productive salmon fishery in the region, with up to 1,200 fish being caught in a single season. Last year, 100 fish were caught. Juvenile salmon - a key indicator of future conditions - are either missing or extremely rare.

The problem has at last been recognised. Last summer, after years of denial, the Scottish Environmental Protection Agency, responsible for protecting Scottish rivers and lochs, finally admitted that the link between sea lice infestation and the decline of wild salmon stocks was 'beyond reasonable doubt'. Now, two committees of the Scottish Parliament are about to embark on an investigation into the environmental impact of intensive aquaculture. But not all fish farmers are willing to admit defeat.

'Lice are not a bad thing,' says Bradley. 'Salmon are a naturally shoaling fish so they are used to being in close contact with other salmon. I've been in salmon farming all my life and when farmed salmon first went on the market the way to judge its freshness was by the number of lice on the fish.'

Colin Adams says: 'That is complete nonsense. The fish farming industry has had serious problems with lice. They are destructive to the farmed fish and they cause them enormous stress. The farms deal with that by treating the salmon but the lice are able to spread into the wild salmon which cannot get treated.'

But 20 years on there can be no turning back the clock. As overfishing of wild stocks makes once-common fish like cod scarce, it will be up to the farmed fish to fill the protein gap in human diets. Projections from the World Bank and the United Nations estimate that by 2020, more than half the fish we consume will be farmed, while world salmon farming is projected to treble from 600,000 tonnes in 1997 to 2 million in 2010.

Is there any way this need for farmed fish can be squared with producing a clean product that does not damage the environment?

Kirsty McCallum believes the answer lies in the Northern Isles. Here, in the shallow, fast-flowing voes at the confluence of the Atlantic and the North Sea, Britain's first organic fish farm industry is gathering pace. On Soil Association-certified farms such as Bruce Mainland's in Orkney, salmon are being produced at about half the densities of the conventional farms without the use of toxic chemicals or colourings. The fish are handfed, using meal made from crushed shrimp shell and organic vegetables. Only 24 per cent oil is allowed by the organic standards so the texture and flavour are light and natural. And, crucially, the tidal flush is high so lice and disease are rarely a problem, and there are no wild stocks to pollute anyway.

'If we could start all over again, salmon farms wouldn't still be sited in the sea lochs up the west coast,' says McCallum, managing director of The Orkney Salmon Company, which markets produce from the local farms. 'They would be in areas like Orkney where the water exchange is much better. There have been grave mistakes made in the past.'

'What supports the organic industry is that the consumer knows at the end of the day that they are buying something better,' she adds. 'They might not understand exactly what it is, but they will know that the production methods mean the fish will have been allowed to swim and to live in as natural as way as possible.'

Farmed salmon may be 'polluted'

Farmed salmon can contain up to ten times the amounts of pollutants - including pesticides and chemicals - as are normally found in wild salmon, according to research.

Growing concern about the findings has prompted the World Health Organisation to cut its guidelines on the recommended intake of salmon to a tenth of the previous figure.

Details of the study, which will be disclosed in a BBC2 programme on Sunday evening, show that the farmed fish industry is the fastest growing food sector in the world, and that salmon farming is a production success story.

But the programme claims that the industry has had a catastrophic impact on populations of the wild salmon near the farms.

Apart from spreading parasites and poisoning local marine life, farmed salmon were escaping into the wild and upsetting the genetic make-up of the wild salmon.

Although farmed salmon contains health-enhancing fatty acids, the programme uncovers evidence that farmed salmon may themselves be contaminated with toxins which have implications for human health.

Of the 95 million tonnes of fish trawled worldwide, about one third is not for human consumption but used to make fish oil or meal for livestock.

Dr Michael Easton, who recently carried out a pilot study for Canada's David Suzuki Foundation, told the programme: “The results were very very clear - farmed fish appeared to have a much higher level of contamination and in wild fish the difference was extremely noticeable."

He said the problem lay in the food fed to captive salmon, which was made from species trawled from the world's oceans and concentrated into pellets. The minute traces of toxins are multiplied into a more significant dose.



© Updated by Michael Easton 2009.