No-one should have any difficulty recognizing the wriggling, snake-like common eel – also known as the freshwater eel. It has a long, slimy, sinuous body and a large mouth with a protruding lower jaw containing numerous small teeth. Its fins have become modified, the dorsal and anal fins forming a continuous line around the tail. Only the small pectoral fins bear any similarity to those of ‘normal’ fish.
Although its colouring changes with maturity, the eel is generally black or brown on the upper surface, with yellow or silver sides and a white underbelly.
Adult eels vary greatly in size. The female is larger than the male, reaching lengths of up to lm (40in) – the male only grows to half this size. Slow-growing, they live for up to twelve years before reaching sexual maturity and being ready for migration (though a few may never migrate as they get trapped in their freshwater home.) lb many anglers they are a nuisance, tangling up the line as they try to wriggle free and covering everything in slime – but to the faithful few they provide an exciting challenge.
Follow the feeding
A nocturnal predator and scavenger, the eel uses its strong sense of smell and good eyesight to hunt prey. It is not a fussy eater, feeding mainly on fish, freshwater shrimps and snails. In gravel pits and rivers, eels rooting around on the bottom often cause damage to the spawning grounds of other fish.
The most fascinating feature of this ‘snake’ is its strange life-cyle. The adult eel changes while in freshwater, turning from yellow to silver with the onset of sexual maturity. The head becomes more pointed as the eel ceases to feed – the fish stores up plenty of fat to sustain it on its long migration – and its eyes become larger, ready to adapt to life in the ocean.
The eel is now ready for migration, a journey which can last up to three years. Some of its passage may be overland. It survives out ofwater longer than most fish by closing its small gills and keeping them supplied with water held in a large gill cavity .
The destination is the Sargasso Sea in the Atlantic, near Bermuda. Although spawning eels have never been captured — this is what makes the eel’s life-cycle so mysterious — young larvae have been found in the plankton in this area. It is thought that the eel spawns in very deep water (up to 400m/1300ft deep). After spawning the eel dies.
When the young eel hatches it is carried by the Gulf Stream (North Atlantic Drift) until it reaches Europe’s shores. During this journey it is transformed from a leaf- shaped larva to a tiny elver or glass eel – so called because its body is transparent. Darkening in colour as it makes its way upstream, the elver wriggles its way into many European waters.
Although extremely athletic, elvers often have problems gaining access to a water. Their task is made easier by man-made eel passes consisting of bunches of twigs covered in wire mesh which assist their journey over locks, dams and weirs. The River Severn is famous for its eel runs, and many elvers are trapped there each year to supply eel farms.
It is much better to start fishing for big eels in rivers, such as the Severn, than in lakes, where they are more difficult to catch.