Fears grow for two-ton whale seen in Thames

First there was astonishment, then there was delight and then, last night, there was deepening anxiety at the most peculiar sight central London has seen in many a day ­ a whale in the Thames.

People gawped. They called to each other and phoned each other. And some of them cheered as the northern bottle-nosed whale, a magnificent creature of the deep ocean, swam past the Tower of London, the London Eye and the Palace of Westminster, to come to rest off Cheyne Walk in Chelsea.

People crowded the banks of London's river to watch, as if it were the Boat Race. Those who were away from the Thames crowded around TVs in offices and pubs to watch it live on screen, to see its great 20ft long, two-ton form surface and blow, surface and blow, for all the world as if it were west of the Shetlands rather than in SW1.

The Thames has the odd seal swim right up the river. It even has the occasional porpoise and dolphin. But never in living memory has leviathan himself graced the capital with his presence. It had a sense of wonder all its own.

There didn't seem to be any big reason behind it. It was hardly climate change. Or even the much-vaunted improvement in Thames water quality. It was just one of those things.

But the very thing that made the sight peculiarly gripping ­ a giant beast being so obviously in the wrong place ­ was what last night held the seeds of a tragedy likely to be played out before an anxiously watching nation. Expert opinion was pessimistic: the chances of London's whale getting back to sea were slim.

Consider: this particular specimen of Hyperoodon ampullatus should be a world away off the continental shelf, diving 600ft down for squid, not anywhere near the coast ­ never mind 40 miles up a comparatively narrow, shallow and polluted river swept by hugely powerful tides.

Last night, the whale disappeared from view for several hours. Then, an unconfirmed sighting in Greenwich brought a glimmer of hope that it was heading seaward, but after divers failed to find the mammal, they ceased the search operation for the night. Save for a handful of dedicated volunteers planning to man the banks of the Thames, they were not due to resume until daybreak today.

According to Richard Sabin of the Natural History Museum, it was possible that the whale was weakened, perhaps through parasite infection, and had been pulled up the river from the estuary by the force of the incoming tide. While in the river, he said, it would be unable to feed, as it was adapted to hunt specialised prey, and so would grow constantly weaker. Fresh water would eventually blister its skin.

It was possibly disoriented by the noise and activity of the busy river and risked beaching itself ­ indeed it did so twice, briefly, yesterday afternoon, in the neighbourhood of the Albert Bridge as the low tide uncovered the Thames foreshore. It was pushed off again by marine mammal medics from the British Divers Marine Life Rescue centre. But the animal seemed to have injured itself during one of its beachings and blood could be seen clouding the Thames.

A British Divers Marine Life rescue boat was on standby should any further sightings be reported, but last night they admitted that they were extremely concerned about its condition.

The chairman of the group, Alan Knight,warned that even if the whale were located, a rescue operation might not succeed. "A vet will assess the whale, and if it is viable then we will use lifting pontoons and a mat and lift it with a crane to take it back to the estuary," he said. " But if it beaches and is not in a fit condition to go back, then we will put it to sleep. Everyone wants it to be released, but if it is the right thing to euthanise the animal, then we will."

The whale was first spotted by a Port of London authority launch at 11am on Thursday off Dagenham, east London. Another whale, thought to be of the same species, was also seen during the morning, off Southend.

Then at 3pm on Thursday it was seen by staff at the Thames Barrier at Woolwich. Eyebrows were really raised, however, yesterday morning when it appeared right in the middle of the capital. "At 8.30am today we got a phone call from someone on a train who thought they had just hallucinated and seen a whale going up the Thames near Waterloo Bridge," said Mr Knight.

A deep sea diver that's as long as a bus

* The northern bottle-nosed whale, Hyperoodon ampullatus, can grow to be the length of a traditional London bus, 33ft, with females about 24ft.

* The worldwide population is not known, but they were seriously depleted by whaling during the last century.

* They are not currently hunted but can get caught up by trawls for other species.

* They swim in family groups of up to 10, with a male typically accompanied by several females and offspring.

* Killing or harming any in British waters is illegal.

* They are believed to be the deepest-diving species of whale, but like all mammals are unable to breathe underwater.

* They have only two teeth, and eat squid, starfish and herring.

* Part of the beaked whales family, they are easily identifiable by their rounded bodies and bulbous foreheads.

* Although they are occasionally sighted off the north-west coast of Scotland, they prefer the deep, cold waters of the Arctic and North Atlantic oceans.

* They are thought to live to an average age of 37.