When eels arrive in the UK as tiny babies, called elvers, they do so at the end of an exhausting 4,000-mile marathon swim from the Sargasso Sea where they have spawned. For generations, their arrival was greeted with much anticipation by fishermen on the Rivers Severn and Wye where they were caught at night and often used in dishes and delicacies.

But the eel is in trouble and has been placed on the Red List of Fish to Avoid by the Marine Conservation Society who class it as critically endangered. However, others believe that the decline in the number of eels is not just a result of over-fishing but is also due to the way in which rivers are managed and flood defences are erected, so blocking the eels migratory route, and that by leaving them to their own defences the eels' fate will be sealed.

Helen Mark meets some of the people involved with trying to save this precious and mysterious creature including fisherman Richard Cook who has a life-long passion for eels and who is now taking tanks of eels into schools to teach the children who look after them for a few weeks about the importance of the fish, our rivers and the environment . Eventually, the children will release the eels back into the river as part of a restocking project.

Helen also hears from Bernadette Clarke of the Marine Conservation Society about the reasons why they felt it was important that eels should be classed as critically endangered and placed on the Red List. And Helen meets Andrew Kerr of the Sustainable Eel Group which is working to devise a recovery plan to protect and preserve the eel.

Presenter: Helen Mark

Producer: Helen Chetwynd.