半滑舌鳎养殖群体的性比与雌雄形态差异比较

Study on sex ratio and comparison of morphological variation between genders of cultured half-smooth tongue sole(Cynoglossus semilaevis)

为研究半滑舌鳎养殖群体幼鱼阶段的性比变化,实验用分子标记法鉴定半滑舌鳎遗传性别,用组织切片方法鉴定表型性别,并比较了表型雌雄的生长差异。结果发现,在半滑舌鳎幼鱼阶段,在遗传性别上,雌雄所占比例约为1∶1,差异不显著(P>0.05)。在表型性别上,雌雄比例约为1∶3,差异极显著(P<0.01)。表型雄性中,由遗传性雄性和遗传上为雌性而表型上为雄性的"伪雄鱼"两部分组成。在养殖群体中,表型雌性、伪雄鱼和雄性三者的比例大致为1∶1∶2。养殖现场反映的雌性约占1/4的情况与本研究结果基本一致。本研究没有发现遗传上为雄性,而表型上为雌性的个体。在6～8月龄间,伪雄鱼的全长、体质量处于表型雌性与正常雄性之间,与两者均无显著差异。在相似全长范围内,雄鱼体高小于雌鱼,雄鱼的全长/体高的平均值为4.05,雌鱼的平均值为3.89,雄鱼的全长/体高比值显著大于雌鱼(P<0.05),此比值可以作为区分雌雄鱼苗种的参考。

Studies were conducted to reveal the changes in sex ratio of juvenile half-smooth tongue sole （Cynoglossus semilaevis）in cultured group by identified genetic sex and phenotypic sex with SSR marker and histological section, respectively. Meanwhile, further comparative analysis of growth and morphological characteristics among female, male, and sex reversal male （neo-male）were carried out. The results were as follows. Genetically, there was no significant difference between females and males with the sex ratio 45.5 % to 54.5%; however,only 53.5% of genetic females had ovaries,while 46. 5% of them had testes. The genetic males all had testes, no sex reversal happened. As a whole, the ratio of males was 75. 2% and significantly higher than the ratio of females 24.8 % morphologically （P 〈 0.05 ）. The growth of neo-male half-smooth tongue sole was higher than the normal males,while lower than the phenotypic females between 6 months post hatching （mph）to 8 mph, but no significant difference was found （P 〉 0.05 ）. Interestingly, the body height of the phenotypic females was higher than the phenotypic males when they had the same total length. In general, the average ratio of total length to body height of phenotypic males was 4.05 ,however, the phenotypic females was 3.89. This ratio would be useful for discrimination of the gender of juvenile half- smooth tongue sole.