Journal of

The teleost European eel, Anguilla anguilla (L.), exhibits a striking life cycle. Spawning occurs in the Atlantic Ocean, supposedly in the Sargasso Sea (1), and larvae drift towards the European coast. There, larvae metamorphose into glass eels, which enter into continental waters where they develop as yellow eels (2). After several years, eels undergo a second metamorphosis termed ‘silvering’, which also marks the onset of puberty (3). After these changes, silver eels start their downstream migration toward their oceanic spawning ground, which probably lasts at least 5 months. At the silver stage, eels show a weak gonadal development, which is due to a deficit in the pituitary gonadotrophic function, as demonstrated by Fontaine et al. (4) in early pioneering experi-ments in which they succeeded in inducing full maturity in female silver eels following injections with carp pituitary extract. More recent studies proved that this maturation blockade resulted from both a lack of stimulatory input from gonadotrophin-releas-ing hormone (GnRH) and a strong inhibition by dopamine (DA) (5, 6). In various teleost species, DA has been reported to control the last steps of the gametogenesis (ovulation ⁄ spermiation)