Wildlife expert Lee Evans said: “It’s in grave danger. It’s stuck next to a buoy, only coming up to breathe. It was a lot more active earlier. It’s either stuck or there’s something wrong with it. “Last weekend there was a great big wind from the north which probably pushed it down here. They only ever come to these narrow estuaries when there’s something very wrong. The Thames is far too warm for it and I doubt it can feed.”The whale was first seen by ecologist Dave Andrews who tweeted footage on Tuesday morning, adding: “Can’t believe I am writing this, no joke. Beluga in the Thames.”The message sparked a frenzy on the Kent riverbank, with many locals abandoning their plans and taking to boats to watch the rare spectacle, prompting The British Divers Marine Life Rescue (BDMLR) to urge people not to go on the water. Once considered endangered, the beluga was reassessed last year and it is now listed ‘of least concern’ by the International Union for the Conservation of Nature (IUCN).Richard Sabin, Principal Curator of Mammals at the Natural History Museum, said the video footage of the whale suggested strongly it was a beluga.“The white body colour, absence of a prominent dorsal fin, bulbous forehead and general swimming motion all suggest this very strongly.“The beluga is an Arctic/sub-Arctic species, so is a long way outside its usual range of distribution.”Do you have a question about the Beluga whale?Our Science Editor, Sarah Knapton and Richard Sabin, the Prinicipal Curator, Mammals and Marine Biology expert at the Natural History Museum in London will be answering reader questions about the Beluga Whale that has been spotted in the Thames. Whether it’s about how it got here, pollution, climate change, or what will happen if it remains stranded (or whales in general) we want to hear from you. Leave your questions in the comment section below. Naturalists flooded the banks of The Thames at Gravesend, Kent, after a lost beluga whale was spotted thousands of miles from its home in the Arctic.Although belugas are occasionally seen off the northern British coastline, they are usually in pods, and it is the first time the marine mammal has ever been sighted so far south.Puzzled conservationists initially thought the white hump breaching the water belonged to an albino harbour porpoise, but as it surfaced to breathe its bulbous head and missing dorsal fin confirmed it was a beluga.However initial excitement turned to concern as the whale appeared unable to find its way back out to sea, remaining trapped and ‘thrashing about’ in a 600 square foot area near Tilbury Dock, one of London’s major ports.As evening drew in scores of people watched anxiously through binoculars as huge freight ships sailed over the whale in quick succession and experts warned that the mammal appeared to be “in trouble” after it became sluggish and stopped feeding. The last beluga sightings were off the Northumberland and Northern Irish coasts in 2015, and the mammals are usually only spotted in the North Sea off Scotland.Lucy Babey, Head of Science & Conservation at ORCA, a charity dedicated to the conservation of whales, dolphins and porpoises around the UK Coastline, said: “It’s an incredibly unusual sighting. Crowds gather on the banks of the Thames to watch the whaleCredit:Rob Powell/LNP Keen birdwatcher Gary Taylor, 50, from Kent, took the day off from his job as a property developer to see the whale.“This is a once in a lifetime opportunity. I’ve been out here just watching it for two hours. This is completely unprecedented. You’d usually have to go to the Arctic to see this.”Naturalist Rupert Kaye, 58, also travelled from Putney in London to see the whale.“I heard about it at lunchtime and have never seen anything like this. I saw the bottlenose whale in the Thames a few years ago but this is on another level. You’d have to travel to the far, far north to see this usually. To join the conversation, log in to your Telegraph account or register for free, here. “I’ve seen some great views of it. They’re highly intelligent and have great navigational skills but who knows if it’ll find its way home.”On Tuesday night animal and marine charities were working together to help the whale return to the sea and had a medical team on standby in case it became beached.Danny Groves, from Whale and Dolphin Conservation (WDC), said: “This is a High Arctic species thousands of miles from where it should be in Greenland, Svalbard or the Barents Sea, they are usually associated close to the ice.“He or she is obviously very lost and quite possibly in trouble.”Rob Lott, another scientist at the WDC, said the cetacean was being monitored in case it “live strands” on a sandbank.”It’s a monitoring operation at the moment, obviously the longer it stays in the Thames estuary then it will become more of a concern, so we’ll see what happens in the morning,” he told BBC Radio 5Live. The whale sighting is believed to be only the fifth ever in English watersCredit:Sky News “Considering how far the animal is from it’s range, it may be distressed and so it is vital that onlookers both on land and at sea keep their distance.”Beluga’s are a distinctive species, with flexible necks, no dorsal fin and unlike most cetaceans they can also swim backwards. They are highly social species, living in pods of between two and 25, and communicating with high-frequency sounds. They have even been known to mimic human language. The whale was spotted near Gravesend in KentCredit:Rob Powell/LNP For anyone twitching the #BELUGA its been feeding around the barges (see last tweet for location) for the last hour and hasn’t moved more than 200m in either direction. Still present. Heres another video @RareBirdAlertUK pic.twitter.com/S2qxKJyuuD— Dave Andrews (@iPterodroma) September 25, 2018 Want the best of The Telegraph direct to your email and WhatsApp? 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