Country Matters: The bald-headed crow is no fisherman's friend

All those who know their Belloc will recall that

The common cormorant or shag

Lays eggs inside a paper bag.

If that were the only dubious habit of Phalacrocorax carbo, the bird would have fewer enemies: as things stand, it has become exceedingly unpopular among fishermen, whose quarry it is eating in ever-increasing quantities.

Belloc, as usual, was writing nonsense, for the common cormorant is not the same as the shag, which is smaller. But there is no doubt that cormorants have flourished mightily in recent years: the RSPB now estimates the summer population in Britain at 7,200 breeding pairs, and the winter population at 19,000 individuals, of which an increasing number are visitors from the Continent.

It must be said that the cormorant's looks are against it: with its long, serpentine neck and heavy body, it is not one of nature's most elegant creations. Its generic name derives from two Greek words meaning 'bald-headed crow', and although its head is not actually bereft of feathers, the bird as a whole does have a scruffy, unkempt look.

Whena cormorant sits on a rock with its wings hanging out to dry, it takes on a primeval outline like that of a pterodactyl. Underwater, no doubt, it is a different creature, for in a pursuit-dive after fish it travels at high speed, propelled by its powerful legs and feet.

Still, as Robin Wynde, an expert at the RSPB, points out, one should not condemn a bird for its looks. If humans were so judged, some of us might not fare too well.

What set fishermen against the cormorant are its formidable powers of consumption. The British bird has always been essentially a coastal dweller, nesting on cliffs and offshore islands, and has come inland only during the winter. The European species lives inland permanently. Now the British birds seem to be picking up the habits of their European cousins and tend to stay inland throughout the year.

In the Lea Valley, which runs south from Hertford to join the Thames in the East End of London, predation has become so heavy that Terry Mansbridge, manager of the fisheries there, has compiled an impassioned report calling for positive action. In a count taken in 1954, he says, fewer than 150 cormorants were recorded in the London area, but by 1985 the total had risen to 2,600.

One reason for the increase is the fact that, since the introduction of the Wildlife and Countryside Act of 1981, the cormorant has been protected, and may not be shot except under special licence from the Ministry of Agriculture. Before 1981, the population was kept down to some extent by culling - and, indeed, during the Fifties the ministry ran a control scheme, offering a shilling a beak.

A further cause of the build-up is that, over the past 20 years, many coastal waters have become fished out or polluted, so cormorants have been driven to seek other sources of food. Simultaneously, with the progressive clean-up of sewage and industrial effluent inland, the quality of waterways and lakes has improved dramatically.

In the London area this has encouraged freshwater fish to extend their range into the lower reaches of rivers that used to be polluted, and estuarine species to move farther upstream. (The fact that salmon are now found regularly in the Thames is an indication of the trend.)

Add to this the fact that in the early Seventies Thames Water began stocking its reservoirs with thousands of trout, and there has been every incentive for cormorants to move in.

Coarse fishermen feel particularly aggrieved, for the evidence suggests that the birds prefer fish about 8in long; most artificially reared trout are bigger than this, so the weight of attack falls on species such as bream and roach.

Debate rages about how much an adult cormorant eats. The figure given by the RSPB is 1lb of fish a day, but anglers say this estimate is based on the intake of captive birds, and that wild ones burn up far more energy. Dr Mark Feltham, an expert from Liverpool University, suggests that the true amount is between 2lb and 3lb a day.

Even at the lowerfigure, the consumption of a resident colony is enormous. In his report, Mr Mansbridge computes that the cormorants now living at Walthamstow will eat at least 180,000lb of fish this year, and that in the Lea Valley as a whole they will put away 235,000lb. With coarse fish costing pounds 3 per pound, this means they will set the angling clubs back not far short of pounds 750,000.

Whenever ponds are drained or netted for research purposes, dead fish are found with single puncture-wounds in their sides - apparently victims of botched attacks - and though plenty of large and small live fish are discovered, in general there is a dearth in the 8in range.

Landowners can, in theory, obtain licences from the ministry to shoot some of the marauders; in fact, the number of such permissions went up from three or four in 1992 to 24 last year. But the law, as it stands, makes the acquisition of a permit slow and difficult.

The RSPB is characteristically cautious on the issue. It did not acknowledge receipt of Mr Mansbridge's report, a copy of which he sent to the headquarters in Bedfordshire. The society claims that shooting is 'not proven' to be an effective means of population control and recommends that if guns are used at all, they should be brought into action only to alleviate acute local problems and to scare birds away.

The Department of the Environment has commissioned a working group to discover what research is required, but it will take years to produce any practical result. Meanwhile, fishermen may take matters into their own hands - as they are already doing in Denmark.