Thames harbour seals
Did you know that the Thames Estuary has an important population of the harbour seal? As one of the Thames’ wildlife secrets, little is known about the inquisitive animal. ZSL hopes to answer some of the fundamental questions about how the seal uses the waters of our busy capital city.
The harbour seal (also known as the common seal) has seen a dramatic decline in some areas of Scotland. The reason for this decline is unknown and may be as a result of climate induced changes, shifting prey species, disease, disturbance or competition with the grey seal. Harbour seal populations are also shifting south, and the waters of the Thames Estuary are increasingly important for their survival.
Harbour seals in the Thames Estuary are the least understood in UK. Understanding the range of the species in terms of foraging sites and haul out sites (where seals come on land to moult) are key areas of research that have practical implications for management. We hope that our harbour seal tagging project will be able to answer some of these questions.
In January 2012 ZSL, along with the Sea Mammal Research Unit (SMRU) of St. Andrews University deployed ten satellite tags on Harbour seals in the Thames estuary. Five seals were tagged in each of two colonies near Southgate and Margate Sands. Important measurements were also taken from the seals in order to monitor health and gain insight into their diet.
The GPS mobile phone tags, which report directly to a mobile phone, accurately show the position of the animal in ‘real-time’ and can record haul out behaviour with a wet/dry sensor. Depth sensors will allow detailed dive data to be gathered that allows foraging behaviour to be monitored. With this suite of information ZSL hope to vastly broaden our knowledge of the zones seals use within the estuary, what they use each area for and ultimately advise on potential conflicts and how they may be avoided or reduced.
Thanks to funding from the BBC Wildlife fund and the SITA Trust, preliminary maps such as those shown below have lent detailed information that, once collated and analysed, will act as an important resource for conservation planning, development and mitigating human-wildlife conflict in this busy waterway.
Seal movement in the Thames estuary
An individual seal's movement