Catches are rising rapidly as the demand for the sharks' dorsal fins for soup, oil from their large livers, skin, cartilage and meat all grow, says the document from Traffic, the Cambridge-based wildlife trade monitoring organisation.
Yet there are no international agreements setting limits on the catches, and the monitoring of the numbers caught is very poor. Traffic puts the figure at somewhere between 30 million and 70 million a year.
Most of the slaughter is accidental, with the predators caught up in nets put out for other fish. But the shark's fin is regarded as a delicacy in some countries, and trade in these has more than doubled in the 15 years up to 1995. The trade centres on Hong Kong, where a bowl of shark's fin soup can cost up to pounds 60, while the fins themselves can sell for more than pounds 300 a kilo. The colony also imports and exports them from and to dozens of countries.
Sharks can easily be over- exploited because they are not prolific breeders and grow slowly. This autumn, several sharkspecies were added to the official Red List of threatened animals. These include the huge basking shark, a plankton feeder which swims around Britain in the summer, and the largest of the fish- and man-eating sharks, the great white. Both of these species are categorised as ``vulnerable'' - the least-threatened level on the list. Four shark species are classed as endangered, or critically endangered.
The government of the Isle of Man has officially asked the British Government to apply to have the basking shark listed under the Cites treaty, the international agreement which seeks to control or ban the trade in endangered wildlife.
Dozens of the huge, harmless fish, which can weigh several tonnes, arrive in the waters of the Irish Sea around the island in the summer, but local laws prevent them from being caught within the island's 12-mile limit. They are killed for the large quantities of oil in their liver. The Government has not yet decided whether to apply for a Cites listing.
``There's a desperate need for basic information to assess the threat posed by the global trade,'' said Steven Broad, director of Traffic, which is part funded by the World Wide Fund for Nature. ``What we do know is that the trade is vast.''
The hunter that became the hunted
n The shark belongs to Class Chondrichthyes; its skeleton is made of cartilage, not bone.
n There are nearly 400 species of shark, belonging to 19 separate families, distributed over tropical and temperate zones.
n The great white shark is the largest known predatory fish. It grows up to 15ft in length and weighs up to 1,700lb.
n The smallest known shark is Squaliolus laticaudus of the Gulf of Mexico, which never grows to more than 6 inches long.
n The largest fish ever killed underwater by a spear fisherman was a 14ft great white, in 1974.
n An estimated 1,000 people are killed every year by sharks, 70-80 per cent of them off the coasts of Africa, South America, Asia and Australia.Reuse content