An organisation which represents 47 wildlife trusts across the UK said the mammals are dying out as increasing numbers are caught in fishing nets.

The bottle-nosed dolphin population in Scotland's Moray Firth is estimated to have fallen to about 130 - and is believed to be facing further decline.

We are still fishing in ways that result in the deaths of hundreds of dolphins and porpoises each year

Dr Simon Lyster The Wildlife Trusts

The population in waters off Cornwall, in south west England, is believed to have dropped by two-thirds in the last 10 years to about 350.

Now, The Wildlife Trusts are calling for tougher laws to protect the species and its habitats.

Director general, Dr Simon Lyster, said: "Our marine environment is in much more trouble than people realise.

"We are still fishing in ways that result in the deaths of hundreds of dolphins and porpoises each year, and in the destruction of precious and rare marine habitats."

The report said that a record 500 dolphins were found stranded on UK shores in the last year.

Effective protection

Post mortem examinations found that the majority had been injured or drowned in nets.

The Wildlife Trusts' marine policy director, Joan Edwards, said: "The system of marine conservation in the UK is woefully deficient.

"The enormity of these problems demands immediate action and commitment from national and local government to ensure effective protection of the marine environment."

The mammals are threatened by fishing nets

The report - entitled Our Dying Seas? - also calls for the creation of a single government ministry to manage marine resources.

There have been several warnings in recent years about the threat to the future of Scotland's dolphin population and the dangers posed by fishing nets.

The dolphins attract thousands of tourists to the Moray Firth area each year, bringing with them about �750,000 for the local economy.

Last month, police said salmon poachers' nets were the main threat to the dolphin pod.

Pollution and overfishing have also been highlighted as threats to the dolphins.

'Biologically diverse'

A fishing ministry spokesman said many of the proposals suggested by The Wildlife Trusts were covered by a package of initiatives announced in May.

"We are working to deliver a vision of clean, healthy, safe, productive and biologically diverse oceans and seas," he said.

"The government recognises the sense of urgency expressed by this report, and welcomes The Wildlife Trusts' work to highlight these issues.

"But to develop a strategy to safeguard the marine environment for generations to come involves consultation and discussion with all stakeholders."