Reproductive physiology of the Dusky Grouper Epinephelus marginatus (Perciformes: Serranidae) in captivity: hormonal therapies applied to the induction of sexual maturation in pre-spawning phase

Abstract

Reproduction in fish is triggered by environmental factors and controlled endogenously by an endocrine system, mainly by the Hypothalamic-Pituitary-Gonad axis (H-H-G). This axis is responsible for the synthesis and secretion of hypothalamic hormones, pituitary gonadotropins, gonadal steroids and other hormones modulating the reproductive process. Although Brazil has a great aquaculture potential, studies related to Marine Fish Farming are still incipient, with limitations of knowledge in basic processes, considered fundamental for the development of the activity in the country. The production of marine fish presents complicated hindrances in the reproductive processes, more specifically in gonadal maturation, a critical event in which the gonads, under the influence of several hormones and factors, undergo morphological and physiological changes in a cyclic way, to produce functional gametes. This is the current situation of Epinephelus marginatus, a species of hermaphrodite teleost chosen for the development of this project. In Brazil, a great potential for E. marginatus has already been detected (high market value), but difficulties in reproduction, especially in gonadal maturation in the pre-spawning phase, still limit its production. Considering the difficulties encountered in the reproductive process of E. marginatus, the following project aims to understand the physiological mechanisms involved in the HHG axis during the sexual maturation of this species, testing the use and efficacy of long-term sustained hormone release systems to induce gonadal maturation in captivity. The consolidation of the results will be important for the establishment of the rearing of this species that, since it is included in the national list of endangered species, deserves special attention. (AU)