President Bill Clinton has been praised by environmental campaigners for his help in protecting one of the most endangered species of whale.

The species, the northern right whale, is thought now to number only about 300 individuals.

They spend much of their time off the eastern seaboard of the USA and Canada.

With Mr Clinton's support, US representatives to the International Maritime Organisation tabled a proposal designed to give the whales protection from passing ships.

The IMO has agreed unanimously to support the proposal.

Warnings and advice

It means that commercial shipping entering the whales' calving and feeding grounds will now be required to report by radio to the US Coastguard.

The coastguard will then send the ships the latest available information on the whales' locations, and advice on avoiding collisions.

Shipping threatens the whales' survival

The Whale and Dolphin Conservation Society said it warmly welcomed the IMO decision, and applauded Mr Clinton's support for the whales.

The species is known as the right whale because whalers recognised it as the "right" one to catch.

The animals are easy to approach, live close to the shore, and float when they are dead.

They also used to provide large amounts of oil, meat and whalebone.

Hunted down

An international moratorium on commercial whaling has been in force for more than 10 years, and much earlier, in 1937, hunting the right whale was banned.

In the whalers' heyday, though, they were driven close to extinction.

Those that live in the southern hemisphere have been growing in numbers by about 7% in recent years.

But the northern right whale is probably closer to extinction than any of the other great whales.

Fishing gear is also a hazard

There are a very few in the north Pacific, and possibly a handful in the eastern north Atlantic - they used to be abundant between Spitzbergen and the Azores.

The main stronghold of the northern right whale now is from Canada down to Florida.

Even there, though, they become entangled in fishing gear and collide with ships.

Biologists think that shipping accidents represent the greatest human threat to the right whale.

The calves weigh about a tonne at birth, and an adult animal can weigh 80 tonnes.

But females do not have their first calves until they are between five and 10 years old, and then they give birth only once every three or four years.

With a breeding rate as slow as that, it will be a long time yet before the northern right whale recovers - if it ever does.