Genetic effects of marine stock enhancement: a case study based on the highly piscivorous Japanese Spanish mackerel

We used a before–after control–impact design to quantify the genetic effects of the large piscivorous Japanese Spanish mackerel (Scomberomorus niphonius) stock enhancement program on wild populations in the Seto Inland Sea. Samples of 1424 wild and 230 hatchery fish collected from 13 sites around Japan were genotyped using five microsatellite markers. A total of 758 wild and 103 hatchery fish were sequenced for the mitochondrial DNA D-loop region. The population structure of Japanese Spanish mackerel was panmictic around Japan. Hatchery fish had significantly lower genetic diversity indices than did wild fish. However, there was no significant change in any of the diversity indices in the Seto Inland Sea, despite the substantial genetic mixing proportion of hatchery-origin genes (7.8%–14.5% from releases in 2001 and 2002), a conclusion supported by simulations. The estimated effective population size was surprisingly small (∼430–970) but stable in the Seto Inland Sea compared with the l...

本研究采用事前-事后对照影响研究设计（before–after control–impact design），量化了大型食鱼性日本马鲛（Scomberomorus niphonius）种群增殖放流计划对濑户内海（Seto Inland Sea）野生种群的遗传效应。研究采集了日本周边13个采样位点的1424尾野生个体与230尾孵化场繁育个体，利用5个微卫星标记（microsatellite markers）对其开展基因分型；同时对758尾野生个体与103尾孵化场繁育个体的线粒体DNA D-loop区（mitochondrial DNA D-loop region）进行测序。结果显示，日本周边海域的日本马鲛种群整体呈泛交结构，无显著遗传分化。孵化场繁育个体的遗传多样性指数显著低于野生个体。尽管2001年与2002年放流的孵化场个体的遗传基因混入比例达7.8%~14.5%，但濑户内海海域的各项遗传多样性指数均未出现显著变化，该结论得到了模拟实验的支持。估算得到的有效种群大小（effective population size）出乎意料地小（约430~970），但相较于原文未完整呈现的对比内容，濑户内海海域的有效种群大小保持稳定。