Visit London and see the seals? Many marine mammals sighted in Thames

A northern bottle-nose whale swims along the banks of the River Thames in London in 2006.

Story highlights

  • New report: Marine mammals often seen swimming through London
  • Earliest record is of a whale in London in 1240
  • Busiest month for sightings is August, report says

(CNN)Forget Big Ben. That's old hat.

Maybe the city's new tourist slogan should be this: Visit London and sea the seals.
    No guarantees, of course. But if you spot a seal, or maybe a dolphin, you won't be the first.
    Far from it.
    Over the last 10 years, 1,317 people on London's shores and bridges have reported seeing sea mammals -- seals, porpoises and even whales -- in the Thames.
    That is according to a report from the Zoological Society of London, which is collecting reports of marine mammal sightings in the city.
    In case you're interested, your best month would be August.

    Whales in Thames are nothing new

    The figures do not mean that more than 1,300 sea mammals swam though London on the Thames. The same animal might well have been seen by several people. But the animals reported include two varieties of seal as well as porpoises, dolphins, whales and even a couple of otters.
    London is about 70 kilometers (45 miles) up the Thames from the North Sea. So it is safe to say that any sea mammal that shows its face outside the Houses of Parliament, which is reported to have happened many times, has seriously lost its way.
    Not that this is anything new.
    The earliest record of a marine mammal in the River Thames was in 1240. Which, actually, is more than 600 years before the tower housing the bell called Big Ben was even built.
    In any event, in 1240 a whale was spotted, then chased upriver to a place called, appropriately, Mortlake -- where it was then, more's the pity, butchered.
    But, as the Zoological Society of London notes in its report, "Attitudes to marine mammals have changed."
    In 2006, a female northern bottle-nose whale lost her bearings and showed up in London, apparently seeking directions to the North Sea. And there was no talk of butchering at all.
    She was spotted that January by a man named David Dopin, who was on a train. He phoned police from the train to say what most of us would probably say in those circumstances -- that he thought he had just seen a whale in the Thames but probably, in all honesty, he had just been hallucinating.
    Fortunately for Dopin's mental health, he turned not to have been hallucinating at all.
    There really was a whale in London.

    High density of sightings near Houses of Parliament

    She was a juvenile, just a baby, and she was only 16 feet long and weighed a mere 7 tons. By popular consensus, she was named Diana.
    People from all over southern England rallied to the whale's defense. Unfortunately -- following a two-day intensive rescue effort -- Diana died of dehydration, never having seen the North Sea again.
    Marine mammals in the Thames face a variety of threats, from pollution to loss of habitat to collisions with boats, the Zoological Society report said.
    But they still visit London. The greatest density of sightings was at Canary Wharf, the report said. And a high density of sightings also occurred between the Houses of Parliament and the O2 Arena.
    So if you want to see a whale, hanging out near the Houses of Parliament could be your best bet.
    And anyway Big Ben is right nearby.