Rising seal numbers in Thames estuary hide triple threat to populations

Scientists conducting annual count of grey and common seals warn of potential impact of dredging, a deadly virus and predation between species

Adam Vaughan

Wednesday 10 August 2016 09.00 BSTLast modified on Wednesday 10 August 201609.03 BST

Scores of seals loll on the riverbank of the Stour, snorting and bellyflopping as they sun themselves a couple of miles outside Ramsgate’s busy marina.

Far from exceptional, these are just a smattering of the hundreds of seals that the Zoological Society of London (ZSL) hopes to count this week in the Greater Thames estuary. The mammals are sighted as far up as Teddington Lock, and Canary Wharf is a hotspot for seeing them.

A total of 905 common and grey seals were found along the estuary last year, up from 708 during the first survey in 2013, counted from plane, boat and on foot. ZSL’s spotters take advantage of the seals’ moulting season in August, when they shuffle up sandbanks to shed their coat and grow a new one, making double-counting less likely.

But while experts have celebrated the rise of the seals along the Thames, there are fears this year of a triple threat to these marine predators.

Several miles south-east off the coast from Ramsgate is Goodwin Sands, a sort of “spaghetti junction” for seals to haul out after travelling from Europe. It is here that the port of Dover hopes to dredge for sand to expand its operations, a move opposed by many local people and environmentalists.

Joanna Barker, ZSL’s conservation scientist, said she was concerned at the potential impact, after 75% of last year’s grey seals were counted there. “I think, and many other scientists think, it could be quite an important meeting point for seals coming from mainland Europe because it’s one of most eastern sandbanks of its type.

“We are a bit worried about the impact on seals. We would like to see the dredging – if it does take place – it doesn’t take place in important times in seal biology. We wouldn’t want to see dredging in the pupping [breeding] times.”

Continued