半滑舌鳎快速生长及高雌性家系的筛选

Selection of the families with high growth rate and high female proportion in half-smooth tongue sole(Cynoglossus semilaevis)

为查明半滑舌鳎不同家系雌、雄鱼遗传和生理性别比例及其与生长速率的关系,并试图筛选出生理雌鱼比例高且生长快的家系,实验首先建立了22个半滑舌鳎家系,并进行同池养殖以比较生长性能,再选取5个正常雄鱼家系和5个伪雄鱼家系进行遗传性别和生理性别测定。结果发现,不同家系鱼苗不仅生长速度差异显著,而且雌雄比例差异也很显著。筛选出生长快速的家系2个(家系16号和61号),其相对增重率分别为0.81和0.56 g/d;筛选出生长较快的家系4个(家系21、28、57和63号),其相对增重率为0.48～0.53 g/d;筛选出生长速度一般的家系12个,生长慢速家系4个。所检测的5个正常雄鱼(ZZ类型)家系的遗传雌鱼比例平均为51.87%,生理雌鱼比例平均为42.94%,遗传雌鱼转化为生理雄鱼的比例平均为14.08%。相反,检测的5个伪雄鱼(ZW类型)家系的遗传雌鱼比例平均为49.34%,生理雌鱼比例平均为4.45%,遗传雌鱼转化为生理雄鱼的比例平均为91.41%。实验发现半滑舌鳎不同家系在雌、雄生理性别比例上存在明显差异;伪雄鱼后代中的遗传雌鱼更容易转化为伪雄鱼,增加养殖群体中生理雄鱼的数量。研究表明,通过家系选育可以筛选出雌性比例高、生长速度快的半滑舌鳎家系。

The present study aims to uncover the relationship between the phenotypic sex and genotypic sex and the growth rate of male and female half-smooth tongue sole and to select the excellent families with high female proportion.In this paper,we firstly established 22 half-smooth tongue sole families which were cultured in the same pond.Secondly,we identified the offspring＇s phenotypic sex and genotypic sex of 5 normal male families and 5 neo-male families.This study shows that there are significant differences not only in growth rate but also in proportion of male to female.Two fast-growing families（No.16 and No.61）whose relative weight gain rate were 0.81 g/d and 0.56 g/d and 4 relatively fast-growing families（No.21,No.28,No.57 and No.63）,the relative weight gain rate ranges from 0.48 g/d to 0.53 g/d were selected;12 commonly-growing and 4 slow-growing families were selected also.The average ratios of genotypic female and phenotypic female of the 5 normal male（ZZ）families were 51.87% and 42.94%,and the ratio of genotypic female reversing to phenotypic male was 14.08%.Instead,the average genotypic female and phenotypic female ratio of the 5 neo-male（ZW）families was 49.34% and 4.45%,respectively,and the ratio of genotypic female reversing to phenotypic male was 91.41%.In the present study we found for the first time that there were significant differences in phenotypic sex ratio between different families.We also found that the genotypic females in neo-male families were more easily reversed to phenotypic males,which increased the number of phenotypic males in cultured populations.It initially showed that the families with high female proportion and fast growing rate could be selected via family selection,which could provide theories and new technical methods for the breeding and the production of high quality seeding of half-smooth tongue sole.