Thames Marine Mammal Survey

ZSL's Marine Mammal Sighting Survey

harbour sealThe Thames Estuary is home to a number of marine mammals, which can be seen all the way up to Richmond. If you spot a seal, porpoise, dolphin or whale in the Thames Estuary please fill in our online survey to help monitor the population (click 'report a sighting' button on the right).

In the last two years we have focused our conservation efforts on the harbour seal, as they have dramatically declined in some parts of the country. The harbour seal population in the Thames Estuary is not well understood, so we are completing annual population counts and a seal tagging study to better understand their ecology. This work is kindly funded by SITA Trust Ltd, BBC Wildlife Fund and SeaChangers.

In August 2013, we completed a comprehensive count of seals in the Thames Estuary and south-east. This coincided with the harbour seal annual moult, where seals shuffle onto sandbanks to grow a new fur coat for winter, making them much easier to spot. We counted from the air, land and sea at the same time, to cover the largest area and calculate the most accurate number of seals in this region. The survey will be repeated annually so we can see how the population changes over time.

The results of this survey and recent public sightings can be seen on our Marine Mammal Map - have a look and see where species were spotted!

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The first aerial survey focused on Goodwin Sands, a well-known location for larger colonies of harbour and grey seals.

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The first aerial survey focused on Goodwin Sands, a well-known location for larger colonies of harbour and grey seals.

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We used ZSL's 3m RIB (Rigid Inflatable Boat) to meander around the Medway estuary. The survey took place at low tide when more seals are out of the water, so we need a small boat to access the creeks and bays without getting stuck in the shallow water.

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We hired at 12m RIB (Rigid Inflatable Boat) for this part of the survey, so that we could cover the Swale Estuary as well as the sand banks near to Southend-on-Sea.

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A group of volunteers from the Kent Mammal Group completed land surveys around the Medway Estuary and River Stour in Kent.

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We rely on members of the public to let us know if they see any marine mammals in the Thames using our online survey (select the survey button on the right of the map). These public sightings are essential for our conservation work and understanding of marine mammals in the Thames - so please get in touch and keep your eyes peeled!

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