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Annual River Thames seal survey conducted this week

Marine biologists from ZSL (Zoological Society of London) have been scouring the Thames Estuary for seals this week as they carry out their annual seal survey.

The ZSL team have been scanning the shorelines and sandbanks by land, sea and air as they count the current population of harbour and grey seals.

With the survey now in its fifth year, the team of conservationists also look at how other factors can affect seal populations, such as health threats, coastal development and behaviours between species. Next year the annual seal census will also include the first-ever harbour seal breeding survey of the Thames, which it is hoped will increase the accuracy of population estimates.

ZSL’s Estuaries and Wetlands Conservation Manager Anna Cucknell said: “Last year’s survey estimated populations of 964 harbour seals and 1,552 grey seals across the Estuary, so it will be interesting to see how these numbers have changed over the past year.

“These fantastic animals are a real wildlife highlight of the Thames but they also face serious conservation threats – from health risks like phocine distemper virus, which devastated UK seal populations in 2002; the impacts of coastal developments including construction and dredging projects in the Outer Estuary; and increasing evidence of inter-species competition for food and territory as seal numbers recover.

A new action plan to protect the Thames’ iconic marine mammals is currently being devised using data collected by ZSL. The conservation charity are also working in collaboration with Port of London Authority (PLA), RSPCA, Cetacean Strandings Investigation Programme (CSIP), British Divers Marine Life Rescue (BDMLR) and the Royal National Lifeboat Institution (RNLI) to produce this.

The action plan when completed will also allow members of the public to access advice online which will let them know how to spot if a marine mammal is healthy and fine or in need of help, and who to contact if they are worried about an animal.

For more information on ZSL’s ongoing work in the River Thames, including the opportunity to sign-up as a ‘citizen science’ conservation volunteer, please visit:

To report your marine mammal sightings, visit

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