Sex Ratio and Body Weight Analysis of Four-Month Juvenile Turbot (Scophthalmus maximus L.)

Abstract:

In the current study, 4022 individuals composed of 37 families at 4-month-old age were identified and counted based on haematoxylin-eosin staining of histology section of the gonads and macroscopic examination. The statistical analysis showed that the number of male and female were 2426 and 1596, respectively, which reflected a highly significant difference (P<0.01) in sex ratio to the hypothesis of a balanced sex ratio (50% males/50% females). At family level, there were 19 families among 37 families exhibited significant male-deviation from a balanced sex ratio (1:1) (P<0.05). Although the other 18 families showed no significant deviation (P>0.05), 13 of them were male-biased. The significant male-deviation in sex ratio has been confirmed in culture stock of turbot juvenile at 4 months age, which was observed in many families. Meanwhile, 2254 individuals composed of 20 families were randomly selected and weighted. The results demonstrated that no significant difference of body weight has been observed between female and male individuals within population and families for 4 months old juvenile fish, indicating that the selection of weight traits in juvenile stage in selective breeding project did not affect the sex ratio among selective breeding stock. Our study supplied useful information for the mechanism of turbot sex deviation and selective breeding project.