A journey that is as mysterious as its amazing metamorphoses
The message was received on November 18, late in the morning. “This is it! The eels of Oir River are migrating downstream.” It was two months since we were waiting for Eric Feunteun, the Director of theMarine Stationof theNational Museum of Natural HistoryofDinard (Ille-et-Vilaine), to give us the green light. Two months so that, finally, the concurrence of a major flood and a moonless night in the fall should give the fish of the small river in Normandy the starting signal. After living in the river for a few years, silver eels were plunging into their long final journey: 6,000 km, five months of swimming to the Sargasso Sea, on the border of the North Atlantic Ocean. The longest known marine migration, ending in potential breeding and certain death.
“We will be on site today and tomorrow,” the email added. The next morning, they were actually there, at Moulin de Cerisel: Eric Feunteun and his colleague, Anthony Acou, also from the museum, both the guests of this station of the French National Institute for Agricultural Research (INRA), installed in a bucolic landscape, a stone’s throw away from Mont-Saint-Michel. But no trace of eels in the huge trap set by the scientists. “We already got 60 the night before. But last night, the weather was too good, Anthony Acou explained, smiling. The water was too clear. This is the problem, and at the same time, the beauty of the eels: there is almost nothing predictable about them.”
This has been going on for two thousand years. Scientists have been pulling their hair out to understand the life cycle of this mythical animal. In the absence of any trace of milt in river waters, even Aristotle would have given in to day-dreaming. Eels could come only from the “bowels of the earth,” the philosopher wrote in his “History of animals.” As to Pliny the Elder, he assumed that, in order to breed, eels rubbed against rocks dispersing fragments of their bodies which became animated. Born from the rotten flesh of horses, carried away by the May dew, coming out from carp gill or salmon skin … so many hypotheses that are apparently far-fetched, but that have been suggested by great scientists over the centuries.