Center for Advanced Instrumental and Educational Supports, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Fishery Research Laboratory, Kyushu University, Fukuoka, Japan.
PLoS One. 2020 Nov 4;15(11):e0240823. doi: 10.1371/journal.pone.0240823. eCollection 2020.
Stocking hatchery fish can lead to disturbance and extinction of the local indigenous population. Masu salmon Oncorhynchus masou masou, which is endemic across Japan, is a commonly stocked fish for recreational fishing in Japan. To conserve the indigenous resource, their genetic information is required, however, especially on Kyushu Island, the paucity of genetic information for this species has hindered proper resource management. Here, to identify hatchery mitogenome haplotypes of this species, stocked in the Kase River system, Kyushu Island, Japan, and to provide mitogenomic information for the resource management of this species, we analyzed the whole-mitogenome of masu salmon in this river system and several hatcheries potentially used for stocking. Whole-mitogenome sequencing clearly identified hatchery haplotypes, like fingerprints: among the 21 whole-mitogenome haplotypes obtained, six were determined to be hatchery haplotypes. These hatchery haplotypes were distributed in 13 out of 17 sites, suggesting that informal stocking of O. m. masou has been performed widely across this river system. The population of no hatchery haplotypes mainly belonged to clade I, a clade not found in Hokkaido Island in previous studies. Sites without hatchery haplotypes, and the non-hatchery haplotypes in clade I might be candidates for conservation as putative indigenous resources. The whole-mitogenome haplotype analysis also clarified that the same reared strain was used in multiple hatcheries. Analysis of molecular variance suggested that stocked hatchery haplotypes reduce the genetic variation among populations in this river system. It will be necessary to pay attention to genetic fluctuations so that the resources of this river system will not deteriorate further. The single nucleotide polymorphism data obtained here could be used for resource management in this and other rivers: e.g., for monitoring of informal stocking and stocked hatchery fishes, and/or putative indigenous resources.
养殖孵化场的鱼类可能导致当地本土种群的干扰和灭绝。日本特有的马苏三文鱼 Oncorhynchus masou masou 是日本休闲钓鱼中常见的养殖鱼类。为了保护本土资源，需要了解它们的遗传信息，但在九州岛，这种物种的遗传信息稀缺，阻碍了对资源的妥善管理。在这里，为了确定日本九州岛桂河流域养殖孵化场的马苏三文鱼的线粒体基因组单倍型，并为该物种的资源管理提供线粒体基因组信息，我们分析了该水系和几个可能用于放养的孵化场的马苏三文鱼的整个线粒体基因组。全线粒体基因组测序清楚地识别了孵化场的单倍型，就像指纹一样：在所获得的 21 个全线粒体基因组单倍型中，有 6 个被确定为孵化场单倍型。这些孵化场单倍型分布在 17 个地点中的 13 个地点，表明该水系已经广泛地进行了非正式的放流。没有孵化场单倍型的种群主要属于第一类群，这在以前的研究中没有在北海道发现过。没有孵化场单倍型的地点和第一类群的非孵化场单倍型可能是作为潜在本土资源保护的候选对象。全线粒体基因组单倍型分析还表明，多个孵化场使用了相同的养殖品系。分子方差分析表明，养殖孵化场的单倍型减少了该水系各群体之间的遗传变异。需要注意遗传波动，以防止该水系的资源进一步恶化。这里获得的单核苷酸多态性数据可用于该河流和其他河流的资源管理：例如，监测非正式放养和放养孵化场鱼类，以及/或潜在的本土资源。
