River Thames: from the Great Stink to a river teaming with wildlife

1858 was one of the most significant years for the River Thames. During that particular summer, high levels of human and industrial waste produced such an unbearable foul odour that it drove people to the countryside looking for clean air and forced some government offices by the river to close. This period became known as the Great Stink, and the severity of the problem compelled politicians to commission the implementation of a sewage network that’s still in use today.

In fact, the Great Stink of 1858, led Benjamin Disraeli (then Chancellor of the Exchequer)  to state that the River Thames was “a Stygian pool reeking with ineffable and intolerable horrors” and asked for leave to introduce a Bill that, in his words, would “attempt to terminate a state of affairs so unsatisfactory and fraught with so much danger to public health”.

Another important year for the Thames was 1957, when the river was declared biologically dead by scientists at London’s Natural History Museum as oxygen levels in the water were too low to sustain most forms of life. While these two events represented tragic news for the river, they also marked pivotal changes for its future. Despite all the pollution and sewage issues that still threaten the Thames today, the river is now far from the dead zone it was almost 70 years ago, with many aquatic species calling it home.

According to the State of the Thames Report, conducted by ZSL in 2021, the river has made a surprising recovery with the efforts of conservation organisations, policymakers and companies. 125 fish species are found in the river such as seabass, Dover sole, flounder, the popular roach and the iconic (and critically endangered) European Eel, a snake-like fish that migrates from the Sargasso Sea to European estuaries, such as the Thames. In partnership with other organisations, Thames21 worked on the Thames Catchment Community Eels project from 2020 to 2022 training citizen scientists to map and assess migration barriers, one of the main issues affecting this species, and running workshops and talks.

It might come as a surprise to some, but the Thames is also home to an estimated five species of sharks. Species such as the tope and starry smoothhound sharks use the Thames Estuary as pupping grounds and nursery habitats for their pups, where they remain for up to two years. The tope shark is the most common species in the river and is sadly critically endangered. It’s been historically fished for its meat, fins and liver oil. Going from big to small species, the short snouted seahorse is another unexpected Thames resident. Several juvenile individuals have been reported in the tidal Thames and Thames estuary according to ZSL.

Some marine mammals such as harbour and grey seals can be easily spotted on the Thames’ sandbanks. They have a combined population of around 4,000 individuals living in the river. The grey seals are more commonly seen in the Thames than the harbour seals, despite the latter using the estuary as breeding grounds. Both species are considered top predators, feeding on a variety of fish and crustaceans and going to great lengths to catch their favourite meals.

Also an important part of freshwater ecosystems, many bird species can be spotted in and around the Thames looking for food such as mute swans, cormorants, gulls, mallards, grey herons, and many others. An iconic and common sight on the river is the grey heron, easily recognisable by its grey body and long thin legs, which makes it one of the tallest bird species in the UK.

Besides the year-round residents, the Thames also gets occasional visits from cetaceans such as porpoises, dolphins, and even whales. While it’s unclear why these animals swim into the Thames, there are a few different possibilities: they might be following prey, sadly be in a poor health state, or it can be a navigation error. One of the most famous visitors was Benny the beluga, a beluga whale that was repeatedly spotted in the Thames for around three months in 2018. Specialists believe Benny eventually found his way home after feeding in sheltered areas around the Kent stretch of the river.

While the Thames is certainly in a better state than it was many years ago and there are definitely reasons to celebrate its biological recovery, the river is still very much in need of our protection and better governance. Sewage spills, road and agricultural runoff and plastic pollution pose big threats to river health, along with water level and temperature rise as consequences of climate change. Water companies and the government, with the support of environmental and conservation organisations, should learn from the past to avoid letting the Thames reach another tragic point following the Great Stink and the declaration of its biological death.

 

If you want to learn more about the animals that live in the Thames, keep an eye on our social media series Thames Wildlife Species Spotlight, which every Friday highlights a different species.