Test and gonad characteristics in different genders of cultivated sea urchins (Strongylocentrotus intermedius, Agassiz): First insight into sexual identification

Abstract

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.