Nature features

Catch returns of both adult and returning glass eels which enter our rivers in the spring have been in a continuous and steady decline since the 1970s.

It doesn’t seem that long ago when as a youngster, I’d watch masses of tiny elvers climbing up the shear faces of algae covered pumping station outfalls on Lincolnshire’s many drains and waterways.  I’d watch in wonder, as the elvers would wriggle up a vertical face, driven by pure instinct to migrate upstream in order to find a suitable place in which to reach maturity.

Today unfortunately this is indeed a rare sight, not only in Lincolnshire but the abundance of eels across Europe is sadly in sharp decline. This reduction in stock is thought to be related in part, to the position of the Gulf Stream currents running from the spawning grounds near the Caribbean to the coast of Europe. Other factors influencing and impacting upon our eel stock are, of course, pollution, together with those less obvious factors such as barriers to freshwater migration, over exploitation by commercial fishing and disease.

The Environment Agency is responsible for the management of eel and elver fisheries in England and Wales and we have recently published a national strategy for the management of eels.  The strategy aims to provide sustainable management of eel stocks in England and Wales which will contribute to the recovery of the eel stocks within Europe.

The eel is well known by many anglers as a famous international marine traveller, completing only part of its life cycle in freshwater or around the coast. There is a great deal of mystery surrounding the eel and its biology, indeed it was only until the close of the last century that eels were still believed to have originated from the hairs of dead sailors, or from the hairs of a stallion’s tail, which drifted and mutated into living eels!  Of course today our understanding of the eel is somewhat more scientific, however there is still much we do not know about this mysterious fish. 

Spawning is believed to take place in the spring, deep in the Sargasso Sea between Bermuda and the Bahamas, not far in fact from the equally mysterious Bermuda Triangle.  It is understood that all of our European eels that migrate and spawn within this general area, travelling a distance of some 3,400 miles. 

During spawning the female is believed carry up to 10 million eggs, which following fertilisation develop into larva called leptocephalus, which migrate to the European coast using oceanic currents. This journey takes about 12 months, and the leaf shaped larvae swim at speeds of between one and five miles per hour.

When the larvae reach Europe they change into the "glass eel" stage. These enter freshwater during the spring, with the peak of the migration taking place on the increasing tides in April and May. Here they change colour into the familiar dark elvers which many of us saw as children, using the tidal currents they migrate upstream during the flood tide. The young eels shelter near the river bank during the ebb tide to avoid being washed downstream, and this is when they are more easily caught by elver fishermen. Some eels remain in coastal waters where they feed and grow in the sea, while others may migrate to and from freshwater throughout their life.

Eels live on or near the bottom of rivers and lakes, migrating slowly upstream. During this period they are commonly referred to as yellow or brown eels due to their colour. Many male eels remain in the lower reaches, whereas females often move further upstream. Therefore, females tend to dominate in the upper reaches of a river where the eels are fewer but larger.

Eels feed mainly on invertebrates, although larger individuals may also eat other fish. Eels are often accused of eating large quantities of salmonid eggs and fry, although scientific evidence suggests that this is unfounded.

Male eels stay in freshwater for between 7 and 12 years, maturing at a length of about 36cm. Females stay between 9 and 16 years, maturing at the slightly larger size of 46cm. Eels can live much longer and grow much larger, reaching up to a metre in length. When the fish mature they change to a blue/silver colour (known as "silver eels") and migrate seaward during the autumn, usually on dark, stormy nights. They then complete the journey to the Sargasso Sea where they spawn and die.

I’m sure you’ll agree that our humble eel is a truly extraordinary species that deserves a good deal of respect given the remarkable journey they make in order to inhabit our waterways. The Agency is of course supportive of commercial sustainable exploitation of eel and elver populations, however presently it is not possible to advise on what level of exploitation the stocks can reasonably sustain.   The Agency is extremely concerned about the decline in recruitment, and as precautionary measure would wish to see no expansion of the eel or elver fishery until stocks of this important species begin to recover.

Other Eel Facts.

• Eel blood is extremely toxic, causing muscular cramps, which can effect the heart.  Only 0.1ml/kg is enough to kill a small mammal such as a rabbit!
• Eels are an important staple for many different species, including otter, bittern and heron.
• The current rod caught record for a freshwater eel is believed by many to be the toughest to beat, standing at an amazing 11lb 2oz (5.046 kilos) captured in 1978 from Kingfisher Lake, near Ringwood in Hamps.