Concerns have been raised for a lone dolphin that has been spotted swimming in the Thames in west London.
The mammal, believed to be an adult common dolphin, has been described as looking “extremely disoriented and pretty lethargic” and is being monitored by British Divers Marine Life Rescue (BDMLR).
It was spotted multiple times in west London on Thursday, between Hammersmith and Wandsworth Park, leaving rowers and eyewitnesses “dumbfounded”.
Steve Ormerod, a professor in ecology at the University of Cardiff, filmed the dolphin from Hammersmith Bridge, more than 30 miles from the mouth of the Thames.
“Common dolphins shouldn’t really be this far up the Thames or alone,” he said on X.
Mary Tester, Thames Area Coordinator at British Divers Marine Life Rescue (BDMLR), who was called to the scene, said: “It looks like an adult common dolphin.
“It’s on its own, which is extremely rare, and it looks extremely disoriented and pretty lethargic. So it’s potentially swam up the river, maybe gotten lost, and doesn’t have the energy to swim back where it needs to go.”
She said while it is “really exciting” to see the “beautiful” mammals, it is “a red flag” when they are seen in the Thames.
“Porpoises are fine, seals are fine, but dolphins when they come this far up the river is a warning sign,” she said.
“So if you do see a dolphin in London it’s really important to call us so we can come out and monitor the mammal, and see if there’s anything further we can do to help it.
“We have seen so far this year five pods of dolphins coming up beyond the estuary and into the Thames. Three of those have come into London. All three of those have not survived, unfortunately.”
Luke Denne, who works for environmental non-profit Climate Centre, had been filming in Putney on Thursday morning for work when he spotted the dolphin.
“I live in Brentford and have spotted seals before and heard about porpoises in the river, so I assumed that was what it was until I saw the distinctive dorsal fin and realised it was dolphin,” he said.
An onlooker contacted BDMLR, which sent two medics to monitor the animal’s welfare.
“We followed it up and down the river between Wandsworth Park and Putney as dumbfounded rowers and runners stopped and crowds with their phones out gathered,” said Mr Denne.
“Children were particularly excited, with one group in Wandsworth Park naming it ‘Jo Jo’.
“Mary Tester from BDMLR was immediately concerned for its welfare, and was asking boaters not to follow the dolphin. She said its the fifth this year and sadly none of survived. Usually they might spot one at most.”
A group of dolphins were repeatedly spotted swimming in the Thames in February.
They were sighted as far west as Canary Wharf, and one group appeared to contain a baby.
