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KMID : 0894520200240030225
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Development & Reproduction
2020 Volume.24 No. 3 p.225 ~ p.230
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Mature and Bi-Sexual Phase Gonad Occurrence in Cultured Red Spotted Grouper, Epinephelus akaara
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Hwang In-Joon
Min Byung-Hwa
Baek Hea-Ja
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Abstract
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This study reports the presence of mature and bi-sexual phase gonads in red spotted grouper, Epinephelus akaara after less than a year of cultivation 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 June 2019, the fish were transferred to a net cage and cultured until September. The rearing temperatures ranged from 19.86℃?24.65℃ in the indoor tank and 21.86℃?27.65℃ in the net cage. During the net cage culture period, specimens were randomly selected for histological gonad examination. The highest gonadosomatic index (GSI) value was measured in July (3.38±2.53), and dramatically decreased in August (0.44±0.21) and September (0.42±0.30). In July, some mature fish showed signs of vitellogenic stage oocyte development (vitellogenic and oil droplet stage oocytes), but immature fish were in an early developmental stage containing peri-nucleolus stage (PNS) oocytes. Bi-sexual phase gonads containing spermatocytes 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 and hermaphroditism in the red spotted grouper
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KEYWORD
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Bi-sexual phase gonad, Oocyte, Red spotted grouper, Spermatocyte, Spermatid
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