The number of seals in the UK's Thames Estuary has fallen, according to a survey by the Zoological Society of London (ZSL).

The study found there were 2,866 gray seals in the estuary, down from 3,243 – a fall of 11 percent from the last census undertaken in 2019. During the same period, the number of harbor seals fell 14 percent, from 932 to 797.

"Changes in number can be down to a few factors, such as the variability in the proportion of seals at sea while the survey is taking place, but this is something we want to keep a close eye on," said ZSL Conservation Biologist Thea Cox.

READ MORE

Masks for all as French schools return

Poland declares emergency over Belarus border

The drones fighting rural poverty

Cox insists that, despite the falls, the numbers of both species remain healthy.

"We still have a long way to go in terms of improving water quality and making space for nature, but this healthy, thriving population shows how conservation measures really work – and just how far the Thames has come since it was declared biologically dead in the 1950s," she said.

In addition to seals, the Thames is also home to species such as the European eel, the Dover sole and the short-snouted seahorse.