農業部-水產試驗所全球資訊網農業部-水產試驗所全球資訊網

本計畫以海鱺作為試驗魚種，進行性別控制之研究。先以甲基睪固酮(MT)雄性化海 鱺仔魚，培育至產精，再與一般成熟雌種魚人工繁殖，目前已養殖5批雄性化種魚之 子代(6月齡)，其子代性別皆有雌雄，雌性比例分別為25%, 34%, 60%, 23%及 34%，推估其雄性親魚並不是新雄魚。為探究此原因，另外培育新一批雄性化海鱺 ，在確認海鱺生殖腺已發育為精巢後，停止餵食MT飼料，來觀察海鱺生殖腺的後續 發展變化。結果在MT雄性化海鱺的處理過程中，雖然生殖腺已發育成精巢，且具有 雄性功能(產精)，但只要停餵MT，生殖腺仍會由精巢逆轉回卵巢，其逆轉過程中 ，會有中間性別(intersex)的過渡階段。這是有趣又困難的研究題目，在處理海鱺 雄性化過程中，如何拿捏使其能成為新雄魚，維持其雄性功能的表現，繁殖生產全 雌化子代，這需要更多的研究來探討。

This plan conducted the masculinization of cobia fingerlings by the methyltesterone (MT) administration and cultivated to sex mature, then proceeded artificial insemination with the normal mature female. At present, we have cultured 5 batch of cobia progeny(6 moths old) and identify the sex type by gonadal histology. The female proportion were 25%, 34%, 60%, 23% and 34%, respectively. From result, we estimated that male breeders were normale male, not belong to neomale. We masculined another batch of cobia fingerlings for studying this problem. After masculining all cobia, stoped the oral administration of MT feed and conducted the following gonad development by gonadal histology. From result, although the gonad had grown to testis, also had the male function(spermiation), but as long as stoped feed MT, the testis still reversed to ovary. In reversing process, we can found the intersex stage in cobia gonad. This is an interesting and difficult topic to maintain the male fuction of cobia neomale for a long time and spawn with normal female to produce all-female progeny.