Monitoring UK Marine Mammals

Aerial image from seal survey in Thames Estuary

The UK is home to 24 species of cetacean (whales, dolphins and porpoises) and 2 species of seal (harbour and grey seal), which can be seen around our coast and even in central London! ZSL gathers vital data to better understand the UK marine mammal population and what threats they are facing.

Public Marine Mammal Sightings 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.

Read our ten year report on the public survey, which shows the results of the 1,317 sightings sent to us by the public between 2004 and 2014. PDF icon Thames Marine Mammal Sightings Survey Ten Year Report 2004-2014 (2.59 MB)

Cetacean Strandings Investigation Programme (CSIP)

More than 3,400 cetaceans have stranded on UK beaches over the past six years. ZSL coordinates the collaborative UK Cetacean Strandings Investigation Programme (CSIP), which investigates stranded whales, dolphins, porpoises, marine turtles and basking sharks across the UK. As well as documenting each individual stranding, CSIP also retrieve a proportion of the animals for post-mortem examination to establish a cause of death. If you see a stranding, please call: 0800 6520333

Thames Seal Programme

The Thames Estuary is home to 670 harbour seals, but they are one of the least understood seal populations in the country. ZSL use an annual harbour seal population survey to estimate the number of seals in the Thames Estuary and completed a telemetry (tagging) study to collect vital information on harbour seal movements, foraging and haul out sites. We have set up the Greater Thames Seal Working Group to coordinate research, management and conservation of seals in the Thames Estuary. Find out more about the Thames Seal Programme

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. 

View the full code of conduct 

Marine mammal thumbnail


Interactive Seal/Marine Mammal Map Screenshot

Marine mammal sighting survey

Record marine mammal sightings on our interactive map

Project Information

Key Species

  • Harbour porpoise (Phocoena phocoena)
  • Harbour seal (Phoca vitulina)
  • Grey seal (Halichoerus grypus)
  • Bottlenose dolphin (Tursiops truncatus)
  • Common dolphin (Delphinus delphis)
  • Fin Whale (Balaenoptera physalus)
  • Sperm Whale (Physeter macrocephalus)
  • Humpback Whale (Megaptera novaeangliae)

People Involved

Joanna Barker is the project manager of the Marine Mammal Sightings Survey and Thames Seal Programme.

Rob Deaville is the project manager of the UK Cetacean Strandings Investigation Programme

Partners and Sponsors

  • SITA Trust Ltd
  • BBC Wildlife Fund
  • Sea Changers
  • Bramley Associates
  • Natural England

Partners and Sponsors for CSIP

  • The Scottish Government
  • Welsh Assembly Government
  • Joint Nature Conservation Committee
  • Natural History Museum
  • Marine Environmental Monitoring
  • Scottish Agricultural College