FEMINIZATION OF PROTANDROUS HERMAPHRODITES Centropomus poeyi INTO FUNCTIONAL FEMALES USING 17ß-ESTRADIOL

Juan Manuel Vidal-López, Wilfrido M. Contreras-Sánchez, Arlette Hernández-Franyutti, María de Jesús Contreras-García and María del Carmen Uribe-Aranzábal
 
Laboratorio de Acuicultura Tropical. División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Km 0.5 Carretera Villahermosa, Tabasco, C. P. 86040.
 

Several Centropomid species support important recreational and commercial fisheries in the Gulf of Mexico, among them, the Mexican snook Centropomus poeyi is a unique species that spends most of its life history in fresh water, but requires to migrate to the coasts to spawn. It is considered endemic to Mexico with a distribution range reported only in watersheds discharging to the Gulf of Mexico. Very limited information has been generated concerning its biology, ecology or population status. In our laboratory we have confirmed the condition of protandric hermaphrodite through histological examination. Based on empirical observations, C. poeyi in captivity has advantages over other Centropomids (i.e. large size, high tolerance to handling, grow-out in a wide range of salinities, and fast growth). However, handling broodstock poses complications since females range from 5 to 10 kilograms generating high risk of loss and expenses during maintenance of the spawners. Therefore, the aim of this study was the production of batches of reproductive females at an early age and a small size through induced sex inversion using 17β-estradiol. For this, we conducted a study where low and high dosages of 17β-estradiol (10, 20, and 30 mg kg-1) and (40, 50, and 60 mg kg-1) impregnated in the food were assessed. Fish fed with 50 and 60 mg kg-1 of 17β-estradiol showed 100% feminization, while the control group presented only males (Fig 1). At four years of age, sex-reversed fish remained as females, producing oocytes and were capable of spawning, while fish from the control groups were ripe males with running milt.