The United Kingdom is announcing its first plans for the protection of marine species.

One of several to benefit is the basking shark, the world's second largest fish, whose plight has been arousing increasing concern.

The plans, announced by the Department of the Environment, Transport and the Regions on Monday, are part of the UK's Biodiversity Action Plan, designed to conserve the most threatened species and habitats as part of the UK's commitment to implement the United Nations Convention on Biological Diversity.

The basking shark can grow up to 10 metres long, and weighs between five and seven tonnes. It feeds only on plankton, which it catches by filtering about 2,000 cubic metres of water an hour through its gill rakers.

Varying pressures

The fish, which pose no threat to humans, are the largest found in UK waters. They are sighted here from March onwards, sometimes in large numbers, but nobody knows where they go in winter.

The sharks are threatened by habitat pressure, the availability of food, and by commercial fishing. Large numbers have been caught in the past for their liver oil, meat, cartilage and fins.

The basking shark is the UK's biggest fish

They mature slowly and have very few young, and conservationists say they are one of the shark species most vulnerable to exploitation.

They have welcomed the government's adoption of a formal protection plan, which is to be managed jointly by the Wildlife Trusts, the Worldwide Fund for Nature-UK, and the Shark Trust.

The director of the Shark Trust, Sarah Fowler, said the basking shark was "one of the world's most magnificent marine animals".

"Although protected in the UK, if unrestricted and unregulated fisheries continue elsewhere, numbers will be reduced to a level that may place the basking shark permanently on the route to decline."