Trawlers are killing Britain's coral reefs

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Britain's biggest and most spectacular coral reefs – which were only discovered in 1998 – are already being destroyed by deep-sea trawling, an underwater survey has found.

Coldwater coral reefs known as the Darwin Mounds, which lie 115 miles off the north-west coast of Scotland, are thousands of years old but have been permanently scarred by trawlers, said Jason Hall-Spencer, a marine biologist at the University of Glasgow.

Acoustic surveys and seabed filming have detected linear scars about 40km long which are thought to have been caused by the dragging of the two 5-ton hauls of a trawling net over the delicate coral structures, that extend over an area of 40 square miles, Dr Hall-Spencer said.

"Most of us associate coral reefs with warm, well-lit waters off tropical coasts. It surprises many that the grey, north-east Atlantic harbours these amazing reefs," said Dr Hall-Spencer, a Royal Society research fellow.

"Heavy trawls are bringing up coral that has been in place for thousands of years. We urgently need improved management of offshore areas worldwide, both to protect deep-water habitats and the fish that they support," he said.

The Darwin Mounds consist of individual colonies of lophelia and sebastes coral which can reach 5m (16ft) in height and grow in spectacular circular patches up to 100m in diameter.

"We didn't have any idea that they were so large and so susceptible to trawling. It's like bulldozing the pyramids only worse because these natural structures are older," said Dr Hall-Spencer .

Carbon dating on coral from the Darwin Mounds puts them at about 4,500 years old but the scientists believe some of the coral could have first formed after the retreat of the glaciers at the end of the last Ice Age, about 10,000 years ago.