Joanna Blythman on fish farming

I'D be lying if I said that I was sorry to see Johnson Seafarms in Shetland going down the tube. More like "I told you so". My first reaction, when I heard of the launch of its "No Catch" farmed cod three years ago, was sadness. Here we go again, another fine wild fish was to be debased, just like that sad travesty, the farmed salmon. This was followed by astonishment that any organic certifying body - in this case, the Organic Food Federation - was daft or greedy enough to lend its credentials to an operation which had all the hallmarks of being another flash-in-the-pan goldrush, like ostrich farming and biofuels, brought to you by speculators and venture capitalists who promise everything then don't deliver, not unlike Daniel Day-Lewis's scary oil man in There Will Be Blood.

Of course, I'm sorry for the creditors, who are owed £40 million, and the company's 14 workers who have been made redundant. But not more sorry for them than than the thousands of people - gillies, hoteliers and shellfish growers and divers - who have seen their livelihoods that depended on wild fish and angling destroyed by fish farms. Never, never buy into the idea that fish farming of carnivorous fish (that's fish that eat other fish) like cod or salmon is the green answer to our over-exploitation of wild species in the open seas. The global history of aquaculture is one long tale of environmental pollution and social and economic suffering.

So far, according to the Environmental Justice Foundation, a staggering 38% of the planet's precious mangroves - the swampy forests that protect tropical coastlines from soil erosion, tsunamis and hurricanes - have been destroyed to make way for tiger prawn farms, the sort that grow those tasteless, bouncy specimens that end up in our curries. Mangrove destruction in turn precipitates salt pollution of land that local people depend on to grow food. When the inevitable disease build-up eventually stops production on these enterprises, the global corporations that owned them and fouled them just walk away, and start up more farms elsewhere.

The fact that No Catch cod has gone belly up should crystallise the debate about farmed versus wild fish. It should have established the principle that farmed fish at £20 a kilo is not the white night riding in on a charger to save depleted fish stocks. Fish farming is riven with structural problems. Fish like salmon and cod are notoriously poor converters of food, and almost wholly dependent on wild fish stocks. Their wastes, which are concentrated under packed cages thick with sluggish, bored specimens, debase water quality and spread disease throughout an alarmingly wide marine ecosystem.

Unlike No Catch cod, which was a small outfit, the overwhelming majority of Scottish fish farms are not part of some quaint little cottage industry, but operated by Dutch or Norwegian-owned transnational corporations who have perfected the art of paying as few people as possible to perform the small number of fairly mechanical jobs they create. These companies think they owe us nothing, and are fickle enough to switch production to a lower cost country in the time it takes the euro to strengthen a point against the dollar.

AND yet the dominant thinking within the old Scotland Office, and now I fear, in the Scottish government, is that fish farming is an industry that deserves knee-jerk support. What a tragedy for Scotland that we should have been hoodwinked by such a bankrupt proposition and allowed ourselves to sell down the river the heritage we should have protected: inspirational wild fish and a clean marine environment. Our 30-year love affair with fish farming has proven to be the biggest ecological disaster to hit the west coast of Scotland in living memory.

Perhaps the worst thing about all the over-hyped claims made for fish farming is that it allows us to take our eye off the ball of wild fish stocks. It gives us an excuse to write off the seas and oceans as a source of future sustenance for the world's rising population. But if we can't manage our wild stocks for the common good then we might as well give up now and start looking for another planet to colonise. The penny must drop that, far from taking the pressure off wild stocks, aquaculture depletes them.

Greenpeace, which wisely has always seen fish farming as an environmental threat, not an opportunity, argues that depletion of wild fish stocks can be halted, even reversed, by creating marine reserves, a bit like wildlife parks, where no fishing is allowed and stocks can recover. There is persuasive evidence from New Zealand that stocks can bounce back in just a few years.

But marine reserves are a grown-up, low-tech solution that necessarily entails some short-term pain for fishermen and consumers, and offers nobody any immediate prospect of making money. In discussions of what to do about the looming crash in key fish stocks, we have always been in thrall to the guy with the quick fix, high-tech panacea, which just happens, incidentally, to guarantee a windfall for investors and miscellaneous stakeholders. More fool us.