Monday June 22, 2015 Q&A

European eels are born...


1 ... as a result of spontaneous generation

2 ... only in the Sargasso Sea

3 ... with fins that they lose when they become adults

Question related image
Correct answer: only in the Sargasso Sea. As surprising as it may seem, all the European eels we see – and eat – here on the Old Continent were born thousands of kilometres away, in the Sargasso Sea off the coast of the Antilles. Their life cycle – curious, to say the least – has not yet been described in very precise scientific terms. What we do know is that the eggs hatch at great depths at the bottom of the Sargasso Sea, and that the transparent larvae – leptocephali – are carried by the Gulf Stream over 5,000 kilometres to the shores of Europe in a trip that takes more than a year. At the end of this journey, the glass eels are 5-6 centimetres long. They leave the salt water and enter into an estuary before working their way upriver, crawling over wet ground and climbing river locks if necessary. They then enjoy a relatively peaceable existence in a river or a freshwater pond or marsh where they become pigmented and grow to adulthood, reaching up to 1.50 metres in length. Eventually, the adult eels – males ranging in age from 6 to 12 and females from 9 to 20 – get started on the long trip home. They head back down the waterways to the sea, running the opposite direction as salmon. Some six months later they are back at their starting point, where they mate and reproduce before dying. Properly prepared eel meat is much appreciated by connoisseurs, but two things should be kept in mind when it comes to consuming eels. First, what was an abundant species as recently as the 1970s is now “critically endangered” according to the IUCN. Second, owing to their longevity and their habitat deep in freshwater, eels are one of the most efficient “bioaccumulators” of pollutants discharged into water as a result of human activity. All the more reason to consume with moderation! For a short news on the topic, see this Science paper