Thames Seal Programme

Harbour Seal in the Thames

The Thames Estuary is home to harbour seals, also known as ‘common seals’, and grey seals, but they are some of the least understood seal populations in the country. ZSL is using seal telemetry (tagging), annual population surveys and a public marine mammal sighting survey to gather data to better inform conservation and management. This information will form an integral part of the newly formed Greater Thames Seal Working Group; a platform for collaborative work on the major issues facing seal populations in the Thames Estuary

Why we are there

Research conducted by the Sea Mammal Research Unit (SMRU), has shown dramatic declines in some Scottish harbour seal populations. The reason for these declines is unknown and may be as a result of climate induced changes, shifting prey species, disease, disturbance or competition with the grey seal. The Thames Estuary harbour seal population is becoming increasingly important at a national level, and represents 12% of English harbour seals.

Key Achievements and Goals

The harbour seal telemetry project has produced vital information on where harbour seals move, feed and haul out in the Thames Estuary. This has allowed us to locate the most important habitats for the Thames harbour seal.  The first comprehensive count of harbour seals in the Thames Estuary was completed in August 2013 and the population was estimated at 670 individuals. 

Annual Harbour Seal Population Survey

In August of each year, ZSL carry out a harbour seal population survey in the Greater Thames Estuary using a combination of aerial, boat and land-based transects. The survey covers from Felixstowe (Suffolk) to Deal (Kent) and is timed to coincide with the harbour seal moult period, where seals spend longer hauled out on sand banks to moult their coat. The annual survey is essential to quickly and accurately detect any changes in harbour seal population size.

Harbour Seal Tagging Project

In 2012, ZSL tagged ten harbour seals in the Thames Estuary with GPS Satellite tags, to gather information on harbour seal movements, haul out sites and foraging areas in the Thames Estuary. The data has provided us with crucial information on the most important habitats for harbour seals in the Thames Estuary, which we can use to better inform conservation and management measures.

Greater Thames Seal Working Group

The Greater Thames Seal Working Group (GTSWG) is a group of stakeholders with an interest in seals in the Greater Thames Estuary and was established to provide a platform for collaborative work on the major issues facing harbour and grey seal populations in the region. In February 2014, the Greater Thames Seal Action Plan (GTSAP) was written to identify and address the major conservation and management priorities for the seal populations.

Marine Mammal Code of Conduct

The marine mammal code of conduct for the Thames Estuary was jointly developed by ZSL and the Greater Thames Seal Working Group, to provide advice on what to do when you see a marine mammal in the water or on land.

Public Marine Mammal Sighting Survey

The Thames Estuary is home to harbour seals, grey seals, harbour porpoises and sometimes even dolphins and whales. Since 2004, ZSL has been collecting public sightings of these marine mammals, to help us understand how they use the Thames Estuary. If you are lucky enough to see a marine mammal, please report a sighting

 

Interactive Seal/Marine Mammal Map Screenshot

Interactive Marine Mammal Survey

Record seal sightings on our interactive marine mammal map

Project information

Partners and sponsors

  • Kent Mammal Group
  • Sea Mammal Research Unit
  • SITA Trust
  • BBC Wildlife Fund
  • Sea Changers