A large marine mammal which swam up the Thames into central London today was identified as a northern bottle-nosed whale. It was chased from the bank near Battersea and what looked like blood was seen near its tail.
It was apparently trying to beach itself. One man waded into the river to encourage it to go back into the mainstream but fears were growing about the whale's wellbeing.
A second whale was reported at the estuary mouth near Southend, with reports that it was emitting a high-pitched noise.
Richard Sabin, whales and dolphins expert at the Natural History Museum, confirmed the animal in central London was a whale. It is the first sighting of the species on the Thames since records began in 1913, he said.
The whale was seen by boaters and sightseers swimming past Parliament.
Northern bottle-nosed whales are normally seen in the north Atlantic off Norway and the Barents Sea and off northern Britain and Ireland in the summer.
They have a bulbous forehead and look like a very large bottle-nosed dolphin and usually feed in deep water.
The species can grow to 10 metres in length and is described by experts as "inquisitive", sometimes approaching boats in the north Atlantic.
Alan Knight, of The British Divers Marine Life Rescue group which is on standby to rescue the animal if it beaches, said it was not thought to be fully grown.
They first received reports of the whale making its way up the Thames yesterday.
He said: "Yesterday, we had a report of two whales going up the Thames and we sent divers but we only found one.
"About 6pm it went back out again past the barrier and we thought it was gone.
"Then 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.
"We went out again and found it's a whale, five to six metres long. Initially it was thought to be a pilot whale or a Risso's dolphin.
"It seems to be nutritionally okay and it's still going upstream, which is a good sign. If it goes ashore we will launch a rescue.
"It may be that it's decided to go up there and got lost."
Liz Sandeman, a marine mammal medic, went out on a boat to examine the whale in a lifeboat.
After her close encounter with the creature, she said: "It looks quite healthy and quite relaxed. It's breathing normally and its weight seems good.
"It struggled a bit when it passed under Westminster Bridge but that's the hardest bridge for it to swim past because of the tide.
"It took about 45 minutes for it to get past the bridge and 20 minutes later it was about 100ft further upstream towards Millbank. It's slow but not because it's ill."
The medic, a director of charity The Marine Connection, said boats in the river could be a danger to the animal.
"There's also the noise which could affect it - the Thames is extremely busy," she said.
"The last thing we want to do is stress the animal out.
"Some people think it has lost its way or is not feeling well, but it's very hard to say why it is here."Reuse content