Changes in body weight and plasma levels of reproductive hormones in prepubertal sea bass females with advanced gonadal growth

Resumen del trabajo presentado en el XIII Congress of the Iberian Association of Comparative Endocrinology, celebrado en modalidad virtual del 16 al 17 de septiembre de 2021.
European sea bass (Dicentrarchus labrax L.) is a teleost fish species that presents sexual dimorphism affecting growth. Under culture condition, a substantial proportion of fish develop as males and those exhibiting larger size usually mature earlier during its first year of age (i.e., precocious males). This situation presents economic problems for producers and thus the production of highly female-biased stocks is considered as an opportunity to benefit its aquaculture. Females grow faster than males and mature later, around 3 years old, reaching a marketable size (∼400 g) after 2-year production cycle. Nevertheless, there is limited information about relationships among body weight in females and how this may affect the rate of oocyte development. The objective of this work is to determine those factors that are important links in the mechanisms by which growth influences ovarian development. To this aim, the evolution of growth and reproductive performance of prepubertal females has been determined in a total of seven batches of fertilized eggs that were reared over the first two years of age. Firstly, results show that there are significant differences of growth in females. Secondly, prepubertal females with slower growth remain immature while those fish with faster growth display advanced oocyte development. It evidences that sea bass females are able to undergo advanced vitellogenesis at 2 years of age although the rate of fish entering into advanced puberty varies among sea bass batches. Significant changes among body weight and plasma Fsh, E2, and Igf-1 levels are also observed between immature and advanced females. These findings suggest that these factors are important links that signals growth and nutritional status to the reproductive axis. The present results show that growth performance in female sea bass has indeed some interesting features that merit to be investigated to face its profitability in aquaculture.
This research was financially supported by the Spanish Ministry of Science and Innovation (AGL2016-75400, PUBERTRAIT).