Those dolphins must be brave! Aquatic mammals are spotted in the sewage-filled River Thames that even Boat Race crews struggled to survive

This is the moment dolphins were spotted in the River Thames drawing a crowd to watch them play in the water this morning.

When the dolphins were seen bobbing along the river's surface at Richmond Lock and Footbridge, onlookers called the fire brigade fearing the mammals were trapped.

Eyewitness James Moon, 63, of Richmond told MailOnline: 'I walked over the footbridge, went to the other side.

'There was a couple of fire engines the far side, two fire engines under the bridge and another one coming and sirens and police and I thought this is a bit strange.

'One of the firemen was saying they’d got called out because they thought [the dolphins] had been trapped or they were in distress.

'They clearly weren’t because you could see them surfacing and messing about the two of them close together,' Moon said.

Moon watched the whole scene unfold at around 10:30am. 

He continued: 'They seemed to be fine going up and down occasionally. People were shouting. There’d be a little dorsal fin come up and then you’d see the body come up.

'There were loads of kids there and parents and everyone was watching and taking videos - it was great. Superb. 

'It was a nice sunny day and everyone was coming down and having a look.

'They had a white stripe on them so I think they were white striped Atlantic dolphins. The last one that came up in 2017 got as far as Richmond.'

This is not the first time the aquatic creatures have surprised passers-by in London  and other locations miles from the sea. 

In February, the Royal National Lifeboat Institution (RNLI) came across a whole pod in the capital's river.

 John Robinson, a crew member of the RNLI, said: 'They were approximately two metres in length and incredible to witness right here on the River Thames, especially when they were jumping out of the water.'

And last month, a couple walking their dogs noticed dolphin fins poking out of the River Welland in Lincolnshire.

'We watched them play for about ten minutes. It was incredible to see them playing so close to us,' dogwalker Madi Corby said of her recent dolphin experience.

As exciting as these cetacean sightings are, the Thames is in reportedly grim condition. 

Swimmers and rowers have claimed the river  is sewage-filled and riddled with E.coli.

Even Oxford Boat Race captain blamed E. coli in the water for their loss against Cambridge on Easter Saturday's boat race, saying he was vomiting before the start of dramatic showdown.

Leonard Jenkins said 'it would be a lot nicer if there wasn't as much poo in the water', after dangerously high levels of E. coli was found in Thames by Hammersmith Bridge. 

Despite the Thames' bad reputation, Moon said the dolphins were 'obviously feeding on something,' in the water.

'It means there must be fish alive for them to feed on so that’s quite good. I wouldn’t swim in it myself but people do.'