That is the conclusion of the Environment Agency (EA), which made the surprise discovery during a routine fisheries survey at Greenwich, raising hopes that water quality improvements in the Thames could be the cause.

While seahorses are regular visitors to the coastal waters around the British Isles it is the first time they have been found so far up the Thames and in this part of London.

According to the agency, the recent sightings suggest that there may be more permanent populations around the UK, which it has attributed to the 1981 Wildlife and Countryside Act, enacted in 2008 to protect wildlife.

The EA has carried out regular monitoring of the fish populations within the Thames Estuary since the late 1980s, which it said has enabled it to better understand the importance of the river as a nursery and breeding ground for a number of species of commercial and conservation importance.

EA agency fisheries officer, Emma Barton, said: “The seahorse we found was only 5cm long, a juvenile, suggesting that they may be breeding nearby. This is a really good sign that seahorse populations are not only increasing, but spreading to locations where they haven’t been seen before. We routinely survey the Thames at this time of year and this is a really exciting discovery.

“We hope that further improvements to water quality and habitat in the Thames will encourage more of these rare species to take up residence in the river.”

The short-snouted seahorse, hippocampus hippocampus, can grow up to around 15cm and are relatively rare in the UK, mainly found on the south coast.

Carys Matthews

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