Cold-water coral put at risk by deep-sea fishing

Cold-water corals are far more widespread than previously imagined but their numbers are already threatened by the rise of deep-sea fishing.

Cold-water corals are far more widespread than previously imagined but their numbers are already threatened by the rise of deep-sea fishing.

Until recently, it was thought cold-water corals - which live in almost complete darkness at depths of up to 10,000ft - were largely confined to northern waters off Canada, Scandinavia and the British Isles. However, a study by the United Nations Environment Programme (Unep) has found they can also thrive in warmer seas off the coasts of more than 40 countries from Spain to Surinam.

Unlike their tropical cousins, the cold-water corals do not need sunlight to survive and feed solely on floating microscopic food, such as plankton.

Cold-water corals usually do best in water ranging in temperature from 4C to 13C and at depths of between 650ft and 3,000ft. But they can also live in water as shallow as 130ft and as deep at 20,000ft.

A diverse range of sea creatures depend on cold-water corals for their survival - and the destruction of these deep reefs by bottom-dredging trawlers is a serious issue, said the study's author Professor Andre Freiwald of the University of Erlangen-Nuremberg in Germany. "We are finding not only new species of corals and cold-water corals in new locations but associated organisms such as snails and clams that were believed by palaeontologists to have become extinct two million years ago," Professor Freiwald said. "That was a surprise and we expect many of these surprises in the future as we undertake more scientific missions," he said.

The World Conservation Union said that the development of new fishing technologies for deep-sea fishing - such as bottom trawl fishing using heavy chains, nets and steel plates - was the single greatest threat to deep-sea environments such as cold-water coral reefs.

Klaus Toepfer, executive director of Unep, said that the effort to conserve tropical corals such as the Great Barrier Reef off eastern Australia should be extended to include their cold-water cousins.

"We are only beginning to understand where these life forms are and what their role is in, for example, replenishing deep-sea fish stocks and nurturing other marine living organisms," Mr Toepfer said.

"Cold-water corals may also harbour important compounds and substances that could be the source of new drugs or novel industrial products," he said. "All these benefits could be lost if we mismanage this newly emerging resource ... So it is incumbent upon us to not only better manage deep-sea fisheries but all fisheries so that there is less pressure on the deep and shallow parts of the seas," he added.

Some cold water coral reefs, such as those that stretch along the continental shelves of the east Atlantic from Norway to West Africa are, when combined, bigger than the Great Barrier Reef.

The survey has found substantial cold-water reefs in the Seychelles of the Indian Ocean, the Galapagos Islands of the equatorial Pacific Ocean, as well as reefs off Brazil, Indonesia and Angola.

Although cold-water corals grow at about a tenth of the rate of warm-water corals, they can form fragile lace-work structures, which are particularly vulnerable to damage by trawling.

Some countries, notably Britain, Norway, Ireland and America, already have legislation protecting cold-water corals in their territorial waters. However Unep would like to extend protection into international waters as part of designated marine nature reserves.

Mr Toepfer said: "The discovery that cold-water corals are more numerous and more widespread than thought highlights how the natural world remains full of surprises."