The BBC's Richard Wilson reports on the plight of the basking shark

The harmless sharks are protected in UK waters, but are hunted elsewhere for their dorsal fins, which can fetch �20,000 per tonne as a delicacy in parts of Asia. The government is planning to approach the Convention on International Trade in Endangered Species (Cites) to seek worldwide protection.

Environment minister Alan Meale said: "We want to warn the rest of the world we are in severe danger of losing this fish."

Alan Meale: We are in severe danger of losing this fish

But Sam Pollard of the Marine Conservation Society said further action was needed to stop hundreds of sharks being killed accidentally every year.

She said: "They get caught in fishermen's bottom nets and their injuries mean they cannot survive."

Few sightings

Maritime wildlife expert Colin Speedie has been funded to carry out a three-year research programme to monitor the number of basking sharks off the south-west coast of England.

Jaws: Basking sharks are no threat to humans

Mr Speedie, of Devoran, Cornwall, said: "There have been a number of sightings off the coast recently, but we have had 10 or 15 lean years.

"The worldwide picture is that the numbers of basking sharks is declining quite rapidly."

His research project, which is being funded by the Wildlife Trusts and the Worldwide Fund for Nature UK, intends to ascertain just how many basking sharks there are. Basking sharks can grow up to nine metres (30ft) long and weigh up to seven tonnes.