AN autopsy is now under way on Gilbert the whale, a female northern bottlenose, who has been found washed up dead on a Bournemouth beach.

The whale was discovered last night and conservationists have been at the scene this morning to try to discover how she died.

One theory is that she was caught by rope, because of marks around the body, particularly a deep mark on the whale's beak.

She has deep cuts on her belly, which are believed to have been caused by the seabed, as she thrashed around in an attempt to free herself.

An autposy set to last around 4hours began around 12.30pm and police are maintaining a 300-yard exclusion zone.

A three-man team from the British Zoological Society dressed in white forensic suites measured and photographed Gilbert before making incisions around and along her body.

Dr Paul Jepson, the man who did the autopsy on the Thames whale, is a member of the team.

It is not yet known how long she was dead for but the body could be smelt downwind of the exclusion zone.

A spokesman for Dorset Police said this morning: "Unfortunately Gilbert has been washed up on a beach in Bournemouth and is dead.

"Officers from British Divers Marine Rescue are with the whale and a marine biologist will be attending this morning.

"They request that members of the public do not attend the beach as it is not known at this stage if Gilbert had any contagious diseases."

She was believed to have been spotted floating by a sailor in the evening last night.

A dog discovered the body rolling in a few feet of surf around 9pm last night.

British Divers Marine Life Rescue needed a tractor to pull her up the shore and had Gilbert on the beach by 11pm.

Ben Olsen, an Alumhurst Towers resident at the scene, said this morning: "We saw Gilbert every day last week.

"It's like she was performing just for us. It's so sad."

The six-metre long whale been spotted between Bournemouth Pier and Branksome Dene Chine for a week until Friday.

Her spectular displays of tail flapping and water breaching, usually in the mornings and evenings and for up to 15 minutes at a time, had enthralled watchers from the cliff-tops and beaches.

Gilbert had also surprised experts by not beaching in the shallow water and also apparently feeding on cuttlefish, while the whale's main food source is usually deep sea squid.

Experts had hoped she had managed to move on to the deep waters around the Bay of Biscay before migrating to South Africa.

Sue White, of British Divers Marine Life Rescue, said it was not known what had made Gilbert take a wrong turning into the area.

Gilbert was nicknamed after Nick 'Gilbert' Smith, an RNLI lifeguard who took the first picture.