Life Below Water

Thames River Health is Thriving… According to Seals?!

Scientists have been using seal numbers as a barometer of the river's health.

Conservationists have been studying the seal population of the River Thames and say that the health of the water is ‘thriving’, despite being declared ‘biologically dead’ in the 1950s!

Numbers have been counted every year since 2013.

Researchers from the Zoological Society of London (ZSL) found the river was home to 2,866 grey seals and 797 harbour seals after pupping season.

Marine biologists conclude that the stable numbers of seals in the river indicate reliable levels of fish for them to hunt as well as decent water quality.

Britain is home to 36% of the world’s population of grey seals. As well as the thriving population in the Thames, the Norfolk coast is a popular breeding ground for the marine mammals, plus several sites in Cornwall and the Scottish coast.

If you spot a seal, please remember these important guidelines by Countryfile for enjoying marine life safely:

  1. Don’t get too close – the general rule is remain further away that 20m, and never get in between a seal and her pup, or a seal and the sea.
  2. Keep dogs on a lead – they can cause a lot of distress or even injury to a seal.
  3. Keep noise to a minimum – this includes young children, who should be kept away if they are unlikely to behave comfortably around the seals.


Have you spotted a wild seal? Send us your photos to be featured across our social media!


Posted by Claire Edwards 13 September 2021

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