Sharks, seahorses and eels have been found in the Thames, marking an improvement from the 1950s, when the river was found to be “biologically dead,” according to a new report.
But the State of the Thames report found that the number of fish species found in London’s main river had gone down slightly since the 1990s, and it is unclear why.
Overall the Thames has made an “astounding recovery” since 1957, according to the Zoological Society for London, which produced the new report.
Birds and marine mammals have both seen short-term increases in population numbers.
The improvement in habitats for animals in the Thames comes partly from better water quality, thanks to updated sewage treatment works. The amount of sewage in the river is still dangerous for some animals, the report said.
And it’s not all good news. As well as the declining fish numbers, the effects of climate change on the Thames estuary are shown by the rising sea levels (4.26mm per year at Silvertown in east London) and increasing water temperatures (about 0.2?C per year in the Upper Thames).
Alison Debney, who helped write the report for ZSL, said: “Estuaries are one of our neglected and threatened ecosystems.
“They provide us with clean water, protection from flooding, and are an important nursery for fish and other wildlife. The Thames Estuary and its associated ‘blue carbon’ habitats are critically important in our fight to mitigate climate change and build a strong and resilient future for nature and people.
“This report has enabled us to really look at how far the Thames has come on its journey to recovery since it was declared biologically dead, and, in some cases, set baselines to build from in the future.”