Natural Resources Institute Finland (Luke), Helsinki, Finland.
Organismal and Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
PLoS One. 2020 May 21;15(5):e0232723. doi: 10.1371/journal.pone.0232723. eCollection 2020.
Supplementing endangered fish populations with captive bred individuals is a common practice in conservation management. The aim of supplementary releases from hatchery broodstocks is to maintain the viability of populations by maintaining their genetic diversity. Landlocked Lake Saimaa salmon (Salmo salar m. sebago) has been critically endangered for the past half-century. As a result of anthropogenic disturbance, especially construction of hydroelectric power plants, the Lake Saimaa salmon has become completely dependent on hatchery broodstock. Recently, habitat restoration has been done in one of the former spawning rivers with the aim of creating a new natural spawning ground for the critically endangered population. Hatchery fish releases have also been revised so that in addition to juveniles, adult fish from the hatchery and from the wild have been released into the restored river. We assessed here if a restored river stretch can be used as a natural spawning ground and juvenile production area with the aim of improving genetic diversity of the critically endangered Lake Saimaa salmon. By constructing a pedigree of the released adults, and juveniles sampled from the restored river, we found that the majority of the released adults had produced offspring in the river. We also found that wild-caught spawners that were released into the restored river had much higher reproductive success than hatchery-reared parents that were released into the restored river at the same time. We found no significant differences in genetic diversity between the parent and offspring generations. Meanwhile, relatedness among different groups of adults and juveniles varied a lot. For example, while the hatchery-reared females were on average half-siblings, wild-caught females showed no significant relatedness. This highlights the importance of using pedigree information in planning the conservation and management of endangered populations, especially when artificial propagation is involved.
用圈养繁殖的个体来补充濒危鱼类种群是保护管理中的常见做法。从孵化场亲鱼中进行补充释放的目的是通过维持遗传多样性来维持种群的生存能力。内陆湖塞马鲑（Salmo salar m. sebago）在过去半个世纪一直处于极度濒危状态。由于人为干扰，特别是水力发电厂的建设，塞马鲑完全依赖于孵化场亲鱼。最近，在其中一条曾经的产卵河中进行了栖息地恢复，目的是为这个极度濒危的种群创造一个新的自然产卵地。孵化场鱼类的释放也进行了修订，以便除了幼鱼外，还从孵化场和野外释放成年鱼到恢复的河流中。我们在这里评估了一个恢复的河流段是否可以用作自然产卵地和幼鱼生产区，以提高极度濒危的塞马鲑的遗传多样性。通过构建释放的成年鱼和从恢复的河流中取样的幼鱼的系谱，我们发现大多数释放的成年鱼在河中繁殖了后代。我们还发现，释放到恢复河流中的野生产卵鱼比同时释放到恢复河流中的孵化场养殖亲本具有更高的繁殖成功率。我们没有发现亲鱼和子代表代之间遗传多样性的显著差异。与此同时，不同成年鱼和幼鱼群体之间的亲缘关系差异很大。例如，虽然养殖的雌性平均是半同胞关系，但野生雌性没有表现出显著的亲缘关系。这凸显了在规划濒危种群的保护和管理时使用系谱信息的重要性，尤其是在涉及人工繁殖的情况下。
