Almost 40 per cent of freshwater fish in Britain and Europe are threatened with extinction, a seven-year study has shown. Twelve species identified as being under threat have already died out and the research, the most comprehensive ever carried out on freshwater fish, named 200 others that are under threat.

Eels, the numbers of which have dwindled by an estimated 95-99 per cent since 1980, are among the most threatened species and were classified as critically endangered in Britain and the rest of Europe.

Of the 58 freshwater species found in Britain, the study found, 22 are under threat of extinction, including the golden charr, vendace, gwyniad, schelly, torgoch and Shetland charr. The picture was more optimistic for better-known fish, such as pike, perch, sticklebacks and European grayling, which were all found to be thriving.

On the continent, however, several species were found to be in danger of disappearing forever, including the Chornaya gudgeon, which survives in a stretch of stream less than a mile long in Crimea, Ukraine. The Ammer-see kilch, found only in Lake Ammer-see in Germany, has been seen only three times since 2000, yet in the 1940s was plentiful enough to support a fishing industry.

Others facing a fight for survival include jarabugos in Spain and Portugal, which were described as critically endangered, while the gizani in Greece was said to be vulnerable.

Freshwater fish stocks across Europe have plummeted primarily because so much water has been diverted for human use, leaving many rivers and streams dry for much of the year. Pollution, overfishing and the introduction of alien species and diseases wreaked further havoc on fish populations over the past century.

Researchers were taken aback at the scale of the problem. “The freshwater ecosystem is probably more threatened than any of the others,” said William Darwell of the World Conservation Union (IUCN), the international body which assesses extinction risks to thousands of species of animals and plants. “It’s not a lost cause. But with 200 fish species in Europe facing a high risk of extinction we must act now to avoid tragedy.”

The research, in conjunction with the IUCN, was carried out by Maurice Kottelat, a former president of the European Ichthyological Society, and Jörg Freyhof, of the Leibniz Institute of Freshwater Ecology in Germany. In a joint statement they said that fish should be treated as worthy of conservation rather than being regarded as an agricultural crop.

They published their findings yesterday in the Handbook of European Freshwater Fishesafter receiving funding from North of England Zoological Society, which runs Chester Zoo.

Fresh taxonomic analysis of freshwater fish led to 47 new species being identified. Among those studied was Coregonus lavaretus, a species thought to live in Britain. Analysis showed that it should be regarded as four different species. Of these the powen, C. clupeoides, is found in Loch Lomond and Loch Eck and two nearby reservoirs, the schelly, C. stigmaticus, in the Lake District, and the gwyniad, C. pennantii, in waters near Snowdonia. C. lavaretus itself is now only thought to be in France and Switzerland.

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