Only populations of Basking Sharks, Seahorses and Native Oysters are stable around the shores of Britain, it added.

Thirteen of the 16 "flagship" marine species and habitats are in disastrous decline, the WWF said, proposing a UK Marine Act to enshrine conservation and biodiversity at the heart of government policy and ensure a coherent industrial policy.

"Our marine heritage is in a shameful state for a maritime nation," said WWF expert Jan Brown. "For proper protection we need a long-term holistic approach that integrates development plans with conservation requirements."

The WWF report said: "The Common Skate is so scarce that recent surveys to assess their status didn't find a single one, indicating that numbers are still extremely low and its status remains in severe decline."

Marine habitats from Maerl coral-like algae to Seagrass Beds are also in deep trouble due mainly to bottom-trawling that scrapes bare whole tracts of the sea floor, WWF said.

It said offshore industrial activities like gravel extraction had also badly damaged marine habitats.

These pressures had added to the threats from pollution and invasion of non-native species as climate-warming raised water temperatures and warm water species moved north.

The environmental pressure group complained that Britain only had three national marine nature reserves, and that wildlife protection laws had not kept pace with industrial development.

"WWF believes that a UK Marine Act is the only real solution to the crisis in our seas," Brown said.