基于微卫星标记对长江江苏段鳙增殖放流效果评估

为评估长江江苏段鳙(Aristichthysnobilis)增殖放流效果,本研究基于微卫星标记的亲子鉴定技术,选用10对扩增效果稳定的微卫星荧光标记引物,结合毛细管电泳对江苏省内良种场563尾鳙亲鱼和长江江苏段687尾回捕鳙进行基因分型,并对位点多态性及亲子鉴定结果进行了分析。结果表明,各位点等位基因介于19～55之间,其观测杂合度为0.530～0.909(平均值为0.748),期望杂合度为0.818～0.929(平均值为0.882),多态性信息含量为0.797～0.924 (平均值为0.871); Cervus3.0模拟结果显示,当双亲未知且置信度为95%时, 10个微卫星位点的累积非亲权排除率为99.996%。亲子鉴定结果发现,所有回捕鳙中有42尾与亲本之间存在亲子关系,被确认来源于鳙增殖放流群体,并由此推算此次评估亲本的放流子代对长江江苏段野生群体的贡献率为6.11%。结果显示该研究进行的鳙亲子鉴定技术可为长江鳙增殖放流效果评估工作提供可靠的数据支撑,为长江渔业资源管理提供参考资料。

Microsatellite method assessment of the effects of restocking enhancement of bighead carp (Aristichthys nobilis) in Jiangsu reaches of the Yangtse River

Bighead carp (Aristichthys nobilis), an important cultured freshwater fish in China, is one of the four major Chinese carps. The natural habitation of bighead carp in the Yangtse River has been destroyed because of environmental water pollution and overfishing, among other factors. Stock enhancement of bighead carp has been conducted for years, being regarded as a positive fisheries management tool. Currently, hatchery-reared bighead carp juveniles were released into the natural river system to supplement the wild population in the Yangtse River. However, the effectiveness of these enhancement efforts has not be evaluated to date. The application of microsatellite markers for parentage determination is becoming more acceptable and popular in aquaculture. To analyze the effect of stock enhancement of bighead carp, a parentage test based on SSR markers was applied in this study. Fins of 563 brood stocks of unknown sexes and 687 recaptured individuals were sampled. Ten SSR markers were modified using fluorescent dyes (FAM/HEX). Genotype data of all brood stocks and all offspring were screened using an ABI Prism3 730 sequencer. The results showed that the number of alleles of microsatellite markers ranged from 19 to 55, and the mean observed and expected heterozygosities were 0.748 and 0.882. The range of the polymorphism information content (PIC) was 0.797-0.924. The simulation of parentage assignment for the situation of unknown sexes showed the combined non-exclusion probability of 10 loci was 99.996% using Cervus3.0. The results showed that the 42 recaptured individuals were offspring of brood stocks. The study suggested that the total contribution of the brood stocks to the wild population was 6.11% in the Jiangsu reaches of the Yangtse River. In summary, this study established an evaluation system of "marking brood stocks-releasing offspring-recapturing-parentage assignment" to assess the contribution rate for the large-scale stock enhancement. The evaluation system was used in this study to monitor all offspring of the marked brood stocks, which achieved the goal of one-time labeling and multi-year monitoring. A microsatellite gene bank was constructed using 10 microsatellite loci for brood stocks from 2016 to 2018. Future research should pay more attention to the assessment of genetic differentiation between the released population and wild population. This study will provide technical support for the stock enhancement process of bighead carp.