• Journal of Marine Life Science
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• v.6 no.2
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• pp.88-96
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• 2021

The purpose of this study was to report the intersex identified in the oyster Crassostrea gigas (n=410, SH 43.3±11.4 mm) in the waters around 13 uninhabited islands near Yeosu. The overall sex ratio (male: female) was 1:1.1, but there was a difference between the sampling areas. In Gajangdo, Sogyeongdo, and Jungsamdo, females showed a high ratio of 65% or more, and in Songdo, Chodo, and Buseodo, males showed a high ratio of 65% or more. The overall intersexuality was about 12.8%, which was high in males, about 34.7% in females and 64.3% in males. Intersexuality was the highest with about 43.8% in Chodo of Gamak Bay. Histologically, intersex could be divided into three types: intrafollicular type, interfollicular type and mixed type. Among these three types, the intrafollicular type was the most dominant with about 81.6%. The intersex cause of oysters reported in this study is considered to require detailed research in the future.