Endangered elvers have made a dramatic comeback to British waters following a year of 'perfect' conditions

Helena Horton
The elvers have been in decline since the 1970s - Alamy

Endangered elvers have made a dramatic comeback in British waters following a year of 'perfect' conditions.

The European eel, once plentiful in our rivers and canals, is dangerously close to extinction after it was overfished and its habitat dried up across Europe.

While there are strict controls on fishing and trade of the baby eels, they are under threat from a £3bn underground smuggling ring due to the elvers being a prized delicacy.

The eels, which travel across the Atlantic to breed before returning to Europe in springtime, have benefited in recent years from a European export ban.

This year, however, experts have declared the stock in the River Severn near Bristol as the biggest anyone has seen for decades.

It is thought there are 100 million eels in the river, double what is usually expected. The increase is down to heavy rainfall earlier this year which has led to a rise in the warm freshwater that the eels favour.

Andrew Kerr, from the Sustainable Eel Group, said: "In an average year the Severn Estuary will get around 50 million eels.

"However, this is the best year anyone has seen for decades and it's well in excess of that.

"It's incredibly difficult to estimate eel populations accurately but there could be as many as 100 million this year."

While this is just a tenth of how many there would have been 50 years ago, it is a marked improvement after decades of decline.

Mr Kerr added:  "It shows that eel conservation is working.

"The reason for it is that the weather has just been perfect this year.

"All the rainfall we had over the winter has meant there's a lot more freshwater about and the eels love warm, fresh water."

Eels used to be an iconic species in the Thames, and were a plentiful food supply for working-class Londoners.

Now, they are scarce in the capital's river, but there have been some improvements in numbers since organisations including ZSL worked to clean up the waterway and remove barriers to their migration such as weirs.

So far eel passes commissioned by ZSL have made 138.95 hectares of additional habitat accessible.