BARCELONA, Spain (Reuters) - The United Nations sounded the alarm over the health of the world's oceans on Friday, warning that aggressive fishing threatens little-understood corals that may hold the key to new medicines.

Oil exploration, waste dumping and telecommunications cables pose further risks to mysterious cold water corals, according to a report released ahead of World Environment Day on Saturday which this year focuses on risks to marine life.

The corals, cousins of the creatures that build more famous tropical reefs, live in sunless waters up to 3.5 miles deep but are seriously threatened by deep sea fishing, the United Nations Environment Program (UNEP) said in its report.

Particularly damaging is bottom trawling, which involves pulling huge weighted nets behind ships. The nets drag along the sea floor scooping up all the marine life in their way -- from valuable fish to inedible species and delicate corals. "Arguably the biggest threat to both cold and warm-water corals is coming from unsustainable fishing," UNEP head Klaus Toepfer said in a statement.

"We are only beginning to understand where (cold water corals) are and what their role is...(they) may also harbor important compounds and substances that could be the source of new drugs," he added.

VORACIOUS APPETITE

Environmentalists trying to persuade governments to cut back on fishing to protect reefs and precarious fish stocks are up against a formidable enemy -- a voracious international appetite for seafood.

From sushi in Tokyo to fish and chips on Britain's beaches, consumer demand drives a massive market -- worth an estimated $75 billion a year -- and also supports jobs in coastal areas of many countries where other employment options can be limited.

Fishing of more usual commercial species is depleting stocks at an alarming rate. According to the United Nations, over 70 percent of the world's commercially important fish stocks are over-exploited, depleted, fully fished or slowly recovering.

But tumbling numbers of traditional favorites like cod only encourage some fishermen to turn to more exotic deep sea options like orange roughey or blue ling.

The fate of these fish is intimately tied to that of the slow-growing cold-water corals they live in and around, and it can be hard to catch them without damaging or destroying the reefs.

Some of the delicate, lace-like structures date back up to 8,000 years, and are home to snails and clams until recently thought to have become extinct two million years ago, the UNEP report says.

OIL, WASTE DAMAGE

Even if deep sea fishing is scaled back, seabed telecommunications cables, waste dumping and fossil fuel prospecting would still threaten the fragile coral beds, which scientists say are more extensive than they originally thought.

Found in seas from Norway to New Zealand, some of those in the east Atlantic have already been destroyed, the report said.

And there is little hope of any short-term recovery, as the reefs grow at one-tenth the rate of their tropical cousins.

World environment day aims to highlight their fate, and that of other sea creatures with events from a port cleanup in 2004 Olympics host city Athens, to the launch of an international environment photo competition in Tokyo and Barcelona.

Copyright © 2004 Reuters Limited

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