大菱鲆(Scophthalmus maximus)四月龄幼鱼雌雄性比及体重差异分析

利用解剖观察和石蜡组织切片法，对37个家系共计4022尾4月龄的大菱鲆幼鱼群体进行雌雄性别的鉴别和统计分析。发现其中雌性1596尾、雄性2426尾，雌雄性比为1:1.52，极显著偏离1:1的理论值(P<0.01)。在家系水平上，37个家系中有19个家系的雌雄性别比例显著偏离1:1 (P<0.05)，其余18个家系雌雄性别比例偏离1:1，但不显著(P>0.05)，但其中13个家系中雄性个体比例偏高。研究显示，在群体水平上，人工养殖条件下的4月龄大菱鲆已经出现雌雄性比偏离现象。从37个家系中随机选取20个家系(2254尾幼鱼)测量个体体重，利用SPSS 17.0软件进行数据分析。结果显示，4月龄大菱鲆雌雄个体体重无论在群体还是家系水平都表现为差异不显著。此分析结果表明，在大菱鲆选育过程中，在4月龄时进行的以体重为选育指标的选择不会对选育群体的性比偏离造成显著影响。本研究结果为大菱鲆性比偏离机制研究及良种选育工作提供了参考。

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

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.