Mature and Bi-Sexual Phase Gonad Occurrence in Cultured Red SpottedGrouper

摘要

This study reports the presence of mature and bi-sexual phase gonads in redspotted grouper, Epinephelus akaara after less than a year ofcultivation in a commercial indoor tank and a net cage. In December 2018,juveniles were placed in an indoor tank and cultured for five months. In June2019, the fish were transferred to a net cage and cultured until September. Therearing temperatures ranged from 19.86°C–24.65°C in theindoor tank and 21.86°C–27.65°C in the net cage. During thenet cage culture period, specimens were randomly selected for histological gonadexamination. The highest gonadosomatic index (GSI) value was measured in July(3.38±2.53), and dramatically decreased in August (0.44±0.21) andSeptember (0.42±0.30). In July, some mature fish showed signs ofvitellogenic stage oocyte development (vitellogenic and oil droplet stageoocytes), but immature fish were in an early developmental stage containingperi-nucleolus stage (PNS) oocytes. Bi-sexual phase gonads containingspermatocytes and spermatids were observed in the lumen and several PNS oocytes.By August and September, most specimens showed early-stage ovary development.However, mature testis (in August) and bi-sexual phase gonads (in September)were also observed. These results provide evidence for early puberty andhermaphroditism in the red spotted grouper.