Author:

Keywords:

european eel (anguilla anguilla l), sex differentiation, metamorphosis, garonne basin (fr), maturation, 0608 Zoology, 0704 Fisheries Sciences, Fisheries

Abstract:

Migrating European eel (Anguilla anguilla L.) glass eels were collected annually in the Garonne Basin (France) during 1987-1989 and subsequently raised under freshwater conditions. In 1990 and 1991 sex differentiation, gonadal development, length/weight and eye size were studied in relation to metamorphosis from yellow to silver eel stage. Differentiation from intersexual gonads to testes took place after 2 years and was synchronized with metamorphosis. Differentiated ovaries, however, were already present in 2(+) yellow eels indicating that expression of female gonadal sex was not synchronized with metamorphosis.