The mystery of the eels’ migration to the Sargasso Sea and the Marianas Trench (the deepest point on the planet) has still not been fully understood.

Aristotle wrote that eels were born in the bowels of the earth, and for centuries people have wondered about the origin of the larvae that appeared off the coast one fine day.

The Danish oceanographer Johannes Schmidt dedicated twenty years of his life in the early 20th century to their observation, relentlessly measuring their size. He ended up discovering that they came from the Sargasso Sea and published his thesis in 1922.

In 2006, eels fitted with data transmission tags were released off the coast of Ireland. Fourteen of them were recovered heading towards the Azores, near the Sargasso Sea, 1300 km from their starting point, proving Johannes Schmidt’s theory.

Why do eels go back to spawn there, so far away? Nobody knows yet. There is a European study under way to find out.  

An eel should be shiny and slimy, a sign of freshness. It is even better if they are still alive! Those caught in rivers and lakes are preferable because they will not smell of mud, unlike those from estuaries and ditches.

Smaller eels do not need to be skinned. This difficult procedure is essential for the larger ones. 

Eels are sold fresh and alive, but also cleaned, skinned, and ready to cook, or frozen (whole or in pieces, mostly products of Chinese aquaculture), preserved, smoked (in slices), marinated, and jellied.  

A large fresh eel must be skinned before use. You place its head on a hook, split open the belly and remove the entrails, then pull the skin off. This should be done while wearing gloves in order to protect your hands from the toxins contained in this fish.

Eel is traditionally prepared en matelote, with a wine and onion sauce; au vert with sorrel, spinach, and parsley; Bordeaux style with shallots and red wine; or in bourride, a Mediterranean-style soup with aïoli.

It can be stewed, grilled, or poached; skewered and broiled like the Japanese unagi kabayaki; or pickled or prepared in aspic like the traditional English dish jellied eels, which dates back to the 18th century.

Smoked eel is mostly served with rye bread and lemon, as an hors d’oeuvre, or added to a salad.

Glass eels and elvers are pan-fried with butter and garlic or with olive oil (and bell peppers in Spain). They can be poached quickly and used in omelets.

Fresh eel is very delicate and should be used as soon as possible. They can be stored for up to 24 hours in a refrigerator or cool room at 4ºC.

The eel is a particularly oily fish, and the fat is essentially monosaturated and with a high Omega 3 content.

Like all fish, eels are high in proteins, B group vitamins, and minerals.

Eel blood contains a powerful toxin that is destroyed by cooking. 

There are more than fifteen eel species. They all live in streams, rivers, and estuaries, but also in lakes. The males are always smaller than the females, which can reach 1 meter or even 1.5 meters in length.

The most commonly known are European eels and their close cousins the American eels, and the Japanese eel, which lives in the rivers of Korea, China, the northern Philippines, and Japan.

They have the same life cycle. European and American eels are born in the Sargasso Sea, off the coast of Bermuda in the North Atlantic. Japanese eels are born in the Marianas Trench, in the Philippine Sea. The larvae, measuring 5–10 mm, migrate for hundreds of days carried by ocean currents, and become glass eels during this time (known a pibales in the Bay of Biscay coasts of France. 

Those that escape capture, which is strictly controlled, grow and become elvers.

These live for several years in the sea or in freshwater: the males live for 5–8 years, generally near the coast in the brackish waters of estuaries; the females live much longer, some for 8–10 years, swimming far up watercourses, often moving through underwater plants. During this time, the eels change and become silver eels, while their genitals develop in a spectacular fashion.

Then, always in the fall, the eels set off on their migration towards the Sargasso and Philippine Seas, where the females spawn and die.

Eels are becoming increasingly rare everywhere, victims of overfishing of glass eels (the Spanish and Japanese are quite fond of them), but also of the polluted watercourses, dams, and the shrinking wetlands where they prefer to live. The catching of glass eels is strictly controlled, as is that of adult eels.

In China and Japan, where eels are very popular, they are the focus of an important aquaculture industry. The glass eels are caught in the sea because eels are unable to reproduce in captivity. 

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