ABSTRACT
Papers and books about the Eel and its migration are numerous. However, when reading this literature one could think that the eel is unisex because most studies concern only females. This is probably because females are bigger than males, and thus easier to study: this difference is the basis of this chapter. Male and female European eels, Anguilla anguilla, exhibit important morphological differences which, to our knowledge, have never been pointed out though these differences have a bearing on physiological consequences on their migratory activity (Sébert et al. 2009b, Amérand et al. 2010). One of the main and easily “visible” differences is the size with its immediate consequence on migration: males being smaller must swim faster than females to attain the Sargasso Sea at the same time in order to reproduce! How do they ensure this performance?
