European Eel

Mysterious, slippery fish

The eel is a very slippery and slimy fish, with a body like a snake. It can swim as well as slither on land – for several hundred metres! There are many legends and tales about the eel, which is not surprising considering how many things we do not about it, even if it is a well-known fish. For example, we do not know how eels spawn or what determines the sex. Pretty much all eels in Swedish waters are female, while males are more common in southern Europe. 

155 years old!

Eels can live to a very old age. Back in the day, many people kept eels in their wells. The eel kept the drinking water clean by eating dead animals and other contaminants in the water. Such captive specimens have helped us to learn how old eels can become. “The Brantevik Eel”, who died in 2014, was probably 155 years old at the time. It was dropped into a well in Brantevik, a fishing village in Skåne, in 1859.

Born 7,000 kilometers away

All European eels are born in the Sargasso Sea, across the Atlantic. They immediately begin a long journey: 7,000 kilometres along the Gulf Stream to Europe. Once here, they spread out all across Europe; some swim along rivers and streams into freshwater, while others stay in saltwater or brackish water along the coasts.

There are many obstacles along the way to Europe, including a very intensive fishing of young eels and hydropower plants when the eels try to migrate up through rivers and streams. The eel goes through many different stages during its development, and each stage is so different that for a long time they were believed to be different species. Newly hatched eels are completely transparent and flat. They are known as leptocephali larvae.  

Dies after breeding

When the eels begin to approach Europe, they have reached the next stage in their development, which is called glass eel. The fry are longer, about 8 cm, and are now round instead of flat. The next stage is called yellow eel. European eels live as yellow eels for many years; after 5–20 years as yellow eels, they become sexually mature.

The sexually mature stage is called silver eel. It is now time to return to the Sargasso Sea to spawn. Their eyes grow and their digestive system regresses during the journey to the Sargasso Sea. The eel eats nothing but survives on fat reserves. It is not known exactly how the spawning happens, but the adult eels probably die shortly afterwards – and a new generation of eel larvae begin their journey towards Europe.