The European eel, a freshwater pilgrim
It is not the most beautiful of freshwater fish, we can agree. With its moray eel-like appearance and its serpentine physiognomy, it sometimes takes time to appreciate all the grace of the animal. Have you noticed that if the front part of the body is cylindrical, at the back, it flattens on the sides? As a result, the fins have also evolved at the back, spreading out along the body. Above all, the eel is not difficult. It is one of these euryhaline fish, in other words capable of withstanding waters with very different salinity levels. A definite advantage when, like it, you like to travel, because the original paradise of this nomadic fish remains the Sargasso Sea, a vast calm area of the North Atlantic rich in kelp, an algae that provides an ideal refuge for the reproduction of eels and many other species.
During their ocean migration, the young larvae evolve at different depths – up to 200 m during the day and 1,000 m below sea level at night – to make the most of the Gulf Stream current. A good calculation, given the long route: often more than 5,000 km. As they approach the European coast, the fry take on the local name of “elver”, some of which will swim upstream with inexhaustible energy. Covered in a protective mucus, the eel can even spend long periods out of the water if necessary. It will take almost ten years to reach adult size, sometimes twenty years for females, in fresh or brackish water environments, rather muddy or rich in rocks and shelters; before making a final journey to the Sargasso Sea.
Others will prefer not to attempt the return. These, sterile, will sometimes live up to 50 years.
