In 1957, scientists declared sections of London’s River Thames “biologically dead” due to severe oxygen depletion caused by decades of industrial waste and untreated sewage. The waterway, once unable to support much aquatic life, presented a bleak future for the river’s ecosystem.
Fast forward nearly seven decades, and the River Thames has experienced a remarkable ecological transformation. Today, the tidal Thames and its estuary boast a thriving population of diverse species, including seals, seahorses, and eels. Even several shark species have been documented further down the estuary, signaling a significant turnaround from its previously dire state.
Revival of the River Thames: A Haven for Marine Life
Among the most striking inhabitants of the Thames Estuary are at least five species of sharks, such as tope and starry smoothhounds. Scientists suggest that the estuary may serve as a vital nursery area for juvenile sharks, which highlights the ecological importance of the river’s recovery.
Seals have also made a notable return to the Greater Thames Estuary. According to the latest data from the Zoological Society of London (ZSL), published in January 2026, this area now supports a growing population of these marine mammals, further illustrating the ongoing revival of the river’s ecosystem.
The resurgence of such species underscores the dramatic environmental recovery of the River Thames, yet experts warn that despite this progress, significant challenges remain to ensure the river’s long-term health and biodiversity.