Reproductive biology of the conger eel from the south coast of Brittany, France and comparison with the European eel

• Main Authors: Sbaihi, M., Fouchereau Peron, M., Meunier, F., Elie, Pierre, Mayer, I., Burzawa Gerard, E., Vidal, B., Dufour, S.
• Other Authors: Muséum national d'Histoire naturelle (MNHN), Ressources aquatiques continentales (UR RABX), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), STOCKHOLM UNIVERSITY SWE, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2001
• Subjects: FRANCE; BRETAGNE; [SDE]Environmental Sciences; Anguilla anguilla; European eel
• Online Access: https://hal.inrae.fr/hal-02580308

International audience The gonadosomatic indices (I-G) of female conger eel Conger conger, aged between 2 and 11 years postmetamorphosis, ranged between 0(.)04 and 4(.)78 and were correlated with both age and body length. Microscopical examination of the gonads showed immature ovaries at two main stages of oocyte development, pre-vitellogenic oocytes for I-G1. The immaturity of the conger eels sampled in Concarneau Bay indicates that this species probably spawns in deeper oceanic waters. Radioimmunoassays (RIA) of sex steroids gave low serum levels of oestradiol and of 11-ketotestosterone, but higher levels of testosterone correlated with increase in I-G. Immunoenzymatic assay (ELISA) indicated low serum levels of vitellogenin (VtG), which were significantly correlated with I-G. The pre-vitellogenic and early vitellogenic stages observed in the coastal C conger were similar to the oocyte stages found in the European eel Anguilla anguilla, at the yellow and silver phases of its life cycle respectively. However, other morpho-functional changes, associated with silvering in Anguilla species, such as the increase in ocular index, and regression of the digestive tract, did not occur at the early vitellogenic stage in conger eels. (C) 2001 The Fisheries Society of the British Isles