ABSTRACT
Eels have a complex migratory life cycle (Fig. 1) with the occurrence of two metamorphoses (for reviews: Sinha and Jones 1975, Tesch 1977, Haro 2003, Dufour and Rousseau 2007, Rousseau and Dufour 2008, Rousseau et al. 2009, 2012). They present a typical larval (fi rst) metamorphosis, leptocephali larva being transformed into glass eels. After this drastic transformation, the growth phase starts in the continental waters and glass eels become elvers then “yellow” eels. After many years in freshwater, the yellow eels transform into “silver” eels which stop growing, cease feeding and start their downstream migration towards the ocean and the area of reproduction.
