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 × 103g/m3, suggests that land-based aquaculture of sea urchins at a density of 5 × 103g/m3 can keep the balanced equilibrium on the sex ratio.
Key words: Strongylocentrotus intermedius, test height-diameter ratio, sexual identification, sex ratio in aquaculture.
Abbreviations: GI, Gonad index; GMC, gonad moisture content; HDR, test height-diameter ratio; TH, test height; TD, test diameter; BW, body weight; HWR, test height-body weight ratio; DWR, test diameter-body weight ratio; GW, gonad wet weight.
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