Fishing lines: Invasion of the baby snatchers

A determined angler fishing the Thames could well catch a salmon from the River Shannon within the next couple of years. If that sounds Irish, let me explain.

A determined angler fishing the Thames could well catch a salmon from the River Shannon within the next couple of years. If that sounds Irish, let me explain.

Back in the 1950s, the Thames was so polluted that even eels, the hardiest of fish, couldn't get past London. The P & O line would not allow their boats into the capital, because the witch's brew laughingly called a river was stripping paint from the hulls. If you fell in the Thames, you needed a hospital, not a towel.

The smell was so bad that MPs eventually voted to tidy up their back garden. It wasn't a cosmetic job, either. Helped by new sewage works, the Thames cleaned up its act quicker than a blue comedian who realises that the Pope is in the audience. Fish came back, though the real turning point was the discovery of a 6lb salmon.

Someone (it might have been the aptly named Hugh Fish, then head of the Thames Water Authority) thought it would be an idea to try reintroducing the king of fish. Salmon, after all, were once a familiar sight in the river, though all that stuff about apprentices refusing to eat it more than twice a week is just an urban myth.

So in the early 1970s, stocking started in Thames tributaries. The baby salmon grew, swam out to sea, and after a gap year or two, came back home. At one stage, it even looked as if dreams of a self-supporting stock by the year 2000 would be reality. Some anglers were deliberately fishing for salmon, the first time for almost 100 years. But then money, that old scene-stealer, entered stage left. The water authority who had once done sterling work in bringing salmon back to the river now turned villain. They won permission to reduce the flow over Teddington weir to a level where the salmon physically could not get past to start the long swim upstream.

In 1993, 338 salmon were recorded. In the past few years, the figure has been below 50, despite continuous stocking. More than £2 million has disappeared into the river so far, leading to grumbles that further spending is a waste of money.

Eventually, someone realised that putting in baby salmon from a strain that was used to returning in the autumn, when river levels would be higher, might be the answer. Previously, all the babies came from Scottish stock. Now most are from Ireland's River Shannon.

There have been a few small triumphs. One fish made it all the way into the Kennet, between Newbury and Hungerford, a swim of more than 100 miles from the river mouth. But the odds are stacked against the salmon. As well as predators such as pike, perch and chub, cormorants nobble a lot of the baby fish. More predators are waiting, especially seals, if they make it to sea. And now, I'm told, fishermen are using illegal gillnets to trap those few adult fish that make it back to the Thames.

I fear the latest batch of juveniles, stocked this week, are going to need more than the luck of the Irish.