Determinación de parámetros reproductivos en chame Dormitator latifrons (Richardson, 1844) del sistema Carrizal-Chone, Ecuador

Abstract

The chame Dormitator latifrons (Richardson, 1844) shows a high physiological resistance, ostensible in its ability to survive in oxygen deficient environments and withstand remarkable variations in salinity and temperature, which makes it a species with potential for aquaculture. However, many of its biological reproductive aspects have not been studied. Therefore, due to the importance of the chame as a capture and production fishing resource in Ecuador; the objective of this study was to determine the reproductive parameters in chame Dormitator latifrons of the Carrizal-Chone system, through the macroscopic and microscopic description, gonadal development phases, temporal variations of the gonadosomatic index and oocyte diameters. The collection of D. latifrons was done monthly in three sites of the Chone River Estuary, located in the Sucre canton in the province of Manabí, between February and August 2018 (rainy and dry seasons). The fish were captured with “atarraya” and transported alive to the Centro de Sanidad Acuícola (CSA) of the Escuela de Acuicultura y Pesquería, Universidad Técnica de Manabí, Bahía de Caráquez. In the CSA, the size (cm), the weight (gr) and the sex (H-M) determined based on the external morphological characteristics (genital papilla), was recorded for each specimen. Subsequently, the eviscerated weight of each specimen was recorded and fragments of gonads were taken, which were fixed and processed by the paraffin inclusion technique. From a total of 295 organisms collected, 144 females and 151 males were obtained with a sexual ratio of 1: 1.05. The females presented an average size of 19.82 ± 5.70 cm TL and an average weight of 148.22 ± 140.47 g, while for the males it was 21.04 ± 6.07 cm TL and an average weight of 169.87 ± 154.14 g. As the female matures, the ovary changes its small and translucent appearance with predominance of primary growth oogonies, until reaching a prominent size occupying almost the entire abdominal cavity, with a pale orange color and visible eggs. In males, the testes change their small, translucent appearance to a large size and a milky white color, due to the presence of sperm in the lumen of the seminiferous tubules. The maturation scale of five phases for each sex is adjusted (I Immature, II In maturation, III Spawning capable, IV Regression, V Regeneration) based on macroscopic and microscopic results. The frequency histogram of the average diameter of oocytes in mature females (phase III) shows a synchronous maturation. Although mature females were found in all sampling months, the gonadosomatic index shows a peak of maturation between April and May. The results of this study show that the chame D. latifrons reproduces during all the sampled months, matures synchronously and produces a large quantity of small sized oocytes. These characteristics are favorable for the aquaculture development of the species given that it allows breeding animals to be available at any moment of time and obtain a large quantity of oocytes from a mature female.