Young Seal lying on Tankerton Beach, Whitstable
Credit: Jim Higham

Harbour and Grey Seals

2025 target

Harbour and grey seal population estimates for Greater Thames Estuary.


Widespread across the Greater Thames Estuary. In Kent, the Greater Thames Estuary includes the coastline from Gravesend to Deal, sandbanks and Medway and Swale estuaries. Populations of both species for the entire Greater Thames Estuary appear to be increasing.


Harbour and grey seals are monitored annually (where funding allows) by aerial surveys covering the Greater Thames Estuary. The surveys consistently take place during the first two weeks of August to coincide with the harbour seal moult when more animals will be reliably ashore for counting. Counts are converted to population estimates. These estimates contribute to a long-term dataset that allows for seal population trends to be monitored. Seals are helpful indicators of
general and wider estuarine health including habitat and prey availability.