Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a year, after which no one will ever eat fish again. Almost everywhere fish stocks are collapsing through catastrophic mismanagement. But no one in the rich world has managed them as badly as the European Union.

So when the EU tells Iceland and the Faroes that they should engage in "responsible, modern fisheries management", it's like being lectured by Attila the Hun on human rights. They could be forgiven for telling us to sod off until we've cleaned up our own mess. Unfortunately, this is just what they've done, with catastrophic results.

A feeding frenzy is taking place in their territorial waters, as they rip into the North Atlantic's last great stock: mackerel. As the seas have warmed, the fish have moved north. When they arrived in Icelandic and Faroese waters, those nations argued that their mackerel fishing agreement with Norway and the EU should be changed to allow them to catch more. Norway and the EU refused, so Iceland and the Faroes tore the agreement up and each awarded themselves a unilateral quota of 150,000 tonnes. As a result, the north-east Atlantic mackerel catch has risen almost 50%, and is now well beyond the replacement rate. If the mackerel go, so do the many links of the food chain which depend on them.

No one is negotiating. The EU and Norway argue that Iceland and the Faroes are stealing our fish. But the mackerel migrating around the North Atlantic belong to everyone and no one. What matters is that the harvest is small enough to sustain the stock, regardless of who catches it, and at the moment no one's blinking. Iceland and the Faroes will reduce their quotas when the EU and Norway are prepared to reduce theirs. Brinkmanship by all four parties is trashing our last super-abundant food species.

Tonight, Channel 4 broadcast the latest instalment of Fish Fight, presented by Hugh Fearnley-Whittingstall. It urges us to switch from what supermarkets call the big five – cod, haddock, salmon, tuna and prawns – towards more viable stocks, in particular mackerel.

It's an engaging and powerful programme, and its attempt to prevent discards – throwing a large proportion of the catch overboard because of EU rules – is one that everyone should support. But what about its call to change species?

Our obsession with cod and haddock is trashing the seabed and many of the other species which live there. Species such as mackerel, herring and sardines reproduce quickly. Because they live in mid-water, catching them involves scarcely any bycatch or damage to the seafloor. "The Iceland and Faroes situation has given us a headache," Fearnley-Whittingstall told me. "But are we going to punish local Cornish handliners for doing the right thing?"

I started work on this article in the belief that he was wrong: that switching to less popular species merely transfers pressure onto new stocks. But the research I've done has changed my mind. His campaign would make good ecological sense, were it not for the insanity of a fishing policy which cannot sustain even our fastest-growing fish. The new pressure on mackerel stocks has nothing to do with Channel 4's attempt to persuade us to broaden our tastes, which has not so far been successful. An analysis of sales by Maria McLean at Surrey University suggests no significant or lasting impact on any species. People have stuck with the big five. You wonder what it takes.

The new mackerel fisheries are finding markets far beyond Channel 4's audience. Jogvan Jespersen of the Faroese Pelagic Organisation told me most of the fish his members catch are sold to Nigeria and eastern Europe. There's nothing wrong with this: the Nigerians have as much right to eat fish as we do. Jespersen says the Faroese catch is being sold only for human consumption.

Iceland's industry is another matter. The chart its fisheries ministry sent me shows that over one-third of the mackerel that ships in its waters caught last year weren't fed to people at all. Instead they were turned into fishmeal, which is sold to feed chickens, pigs, other fish and pets and – even worse – to fertilise crops. It's a disgusting, astonishing waste. Already that country has more or less wiped out its blue whiting stocks and killed huge volumes of herring and capelin for the same purpose.

But the government's website tells us something else of interest: that most of the fishmeal and fish oil Iceland sells is bought by Norway and the European Union: the very parties complaining about Iceland's plunder. Any nation which really cared about fish stocks would ban both the production and consumption of meal and oil, except from the waste produced by fish processing factories. A basic principle of marine conservation is that fish should be caught only for human consumption.

As for the UK government, if it wants to establish any credibility in this debate, it should start by sacking its fisheries minister. In Channel 4's programme, Richard Benyon gave the impression of a man without the slightest interest in his brief, let alone any mastery of it. He was unable to identify the common fish species he's supposed to be protecting. After admitting that he's never been on a trawler, he wormed his way out of an invitation.

It would also implement the royal commission on environmental pollution's proposal: that by 2010, 30% of British seas should be no-take zones in which fish could reproduce safely, greatly increasing the size of stocks. The score so far is 0.3%, and this government's contribution has been to abolish the royal commission. It would address the issue highlighted by Emma Cardwell last week: that in 1999 the UK's quotas were handed, free, to anonymous cronies, who then leased them for a fortune to big fishing conglomerates, wiping out the smaller boats.

Yes, let's demand that Iceland and the Faroes stop wrecking our common stocks. But let's not give the impression that we're doing so only in order to wreck them ourselves.