Nature Features

The term "slippery as an eel" wasn't coined for nothing...catching up with these elusive creatures is no easy task.

Just ask the team of researchers who are tracking the movement of South Devon's population of European Eels!

The slithery fish at Slapton Ley are being monitored as part of a European-wide study into why the number of eels heading north to Europe has dropped so alarmingly in recent years.

While they might not be Devon's prettiest creatures, the European Eels (anguilla anguilla) are an important species. But they're in trouble.

Beauty isn't everything...

Because the eel is one of the most mysterious fish in the sea, marine scientists still don't know exactly where they spawn - but they believe it's probably somewhere in the Sargasso Sea, which lies between West Indies and the Azores.

The Gulf Stream brings the eel larvae into Northern Europe, where they make their way into freshwater rivers.

However, fewer and fewer have been reaching European rivers, and the International Council for the Exploration of the Seas has described their numbers as "outside safe biological limits."

Among the possible factors are changing land use in the freshwater environment, and the increased number of impassable barriers. The long-term alteration of currents could also be affecting their numbers.

The eels can still be found in Slapton Ley, the largest natural lake in southern England. It is a designated national nature reserve and a site of special scientific interest.

Here, a team of researchers is monitoring the eels' movement to see what can be done to halt their decline.

Eel researchers at Slapton Ley

The research - known as the Indicang Project - is led by the Westcountry Rivers Trust, with help from the Eel Research Group at Kings College, London; the Environment Agency; and the Field Studies Council, which manages Slapton Ley on behalf of owners the Whitley Wildlife Conservation Trust.

As part of the research, which began in 2004, a successful elver trap has been built at Slapton Ley.

The trap encourages migrating elvers to move up through the green brush and drop into the collecting vessel.

The elvers are then counted and measured, providing the researchers with information about the eels which arrive at the Ley and its surrounding rivers.

Toby Russell of the Westcountry Rivers Trust said: "The main thrust is to get a grip of what the populations are like in the rivers of the South West and to relate that information to changes in the surrounding habitat.

"It's been well documented that we've lost a lot of wetland habitats since World War II, an it's possible various pollutants could be having an impact on the eel population."