Exceptionally high numbers of young eels have been recorded at a pass specially built for them at St Germans Pumping Station.
The early arrival of large numbers of young eels, called elvers, and adult eels has been welcomed by environmentalists.
After decades of poor numbers of young eels returning from their breeding grounds in the Sargasso Sea, a significant improvement has been recorded in 2014 at many sites around the UK.
At the new St Germans Pumping Station, the second largest in Europe, an elver pass has been installed to allow the young eels to migrate into the waterways of the Middle Level catchment.
The catchment covers 70,000 hectares of the Cambridgeshire and West Norfolk fens between the Nene Washes near Peterborough and the Ouse Washes from Earith to Downham.
At the beginning of April the first elvers of the year were seen making their way up the 35-meter long pass from the tidal River Ouse. The elver pass is an angled trough with bristle boards inside it that help the eels to climb up it. They are attracted to it by the fresh water that is trickled down the trough from the upstream side.
Ten thousand “glass” eels were recorded in the first three days of April. Glass eels are the early stage of elvers and are nearly transparent. They are thinner than a shoe lace and less than three inches long.
During the first three weeks of April nearly 50,000 elvers made their way through the pass. This is an exceptional quantity for so early in the elver migration period which lasts from April to October, said Cliff Carson, environmental officer for the Middle Level Commissioners.
Young eels also look for fresh water in the Middle Level catchment to feed in and will spend the next ten to 15 years growing and putting on
fat that will sustain them on their long journey back to their breeding grounds in the Sargasso Sea.
Mr Carson said: “ It is great to see a boom year for elvers after so very many years when their numbers were less than five per cent of the former totals returning to the UK. We hope this improved trend will continue.
“The St Germans Pumping Station elver pass will give excellent access for eels and elvers into the Middle Level rivers and drains that will benefit eel population recovery in the future.”