Thames eel population plunges by 98%

Endangered eels are disappearing from their traditional homes at a 'worrying' rate according to a conservation charity.

Numbers of the European eel, which the International Union for Conservation of Nature considers ‘critically endangered’, in the Thames have plunged by 98% according to the Zoological Society of London (ZSL).

Every year the ZSL’s Tidal Thames Conservation Project places eel traps on a number of the river’s tributaries to monitor numbers.

The European eels, along with the flounder, are considered crucial to monitoring the condition of the Thames as they were the first two fish species to re-colonise it after the Estuary was considered biologically dead in the 1960s.

Last year less than 50 eels were seen in the traps, marking a stark contrast to 2005 when around 1,500 eels were captured.

The charity is now concerned the eel, an iconic East London dish for centuries, is not returning to the Thames.

Scientists believe European eels originate from the Sargasso Sea in the Atlantic and can spend up to three years travelling to waters in Europe.

They remain in catchments, such as the Thames, for up to 20 years before they make a mammoth 6,500km return voyage back to the Sargasso Sea to spawn and die.

ZSL’s tidal thames conservation project manager, Matthew Gollock, said: “Eels are mysterious creatures at the best of times but we are very concerned about the rapid disappearance of the species in the Thames.

“It’s difficult to say what is going on – it could be due to a number of potential factors including changes in oceanic currents due to climate change, man-made structures such as dams and the presence of certain diseases and parasites.

“Other rivers in the UK are also seeing a European eel population decline – so it seems to be a worrying trend.”

Mr Gollock added his fear of any ‘serious and rapid collapse’ of the eel population could have a knock on effect for other species in the river.

Eel monitoring for 2010 begins in April.

Luke Walsh

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