Abstract

Chong Zhao, Weijie Zhang, Yaqing Chang and Pingjin Liu

Ten test and gonad characters in both genders of cultured sea urchins (Strongylocentrotus intermedius, Agassiz) were investigated for sexual identification and sex ratio. Both test (test height-diameter ratio) and gonad characters (gonad index, gonad color and gonad moisture content) were significantly different between male and female sea urchins. For the first time, we report that cultivated female sea urchins are flatter than males. This could provide some new insight into the sexual identification of S. intermedius. The sex ratio of cultured sea urchins kept 1:1 at the density of 5 × 103 g/m3 , suggests that land-based aquaculture of sea urchins at a density of 5 × 103 g/m3 can keep the balanced equilibrium on the sex ratio.