To investigate the population dynamics of anadromous Baltic Sea perch Perca fluviatilis (Linnaeus), we studied the migratory behaviour (arrival to spawning location) and population structure (genetic structure and differentiation) of three closely located (<50 km) populations. Spawning migration lasted for 32–80 days, and passive integrated transponder tag (PIT-tag) data indicated that anadromous perch displayed reproductive homing. Populations were differentiated, despite low levels of gene flow (3%–5%), and differentiation increased with increasing geographic distance. This fine-scaled spatial structuring was likely, at least partly, explained by homing behaviour. Analyses of temporal within-stream substructuring yielded inconclusive results, so further studies are required to evaluate this. Taken together, our findings highlight the potential for fine-scaled genetic structuring in anadromous perch and indicate that multiple mechanisms, such as isolation by distance, homing, and reproductive timing could contribute to this pattern. This illustrates the importance of considering cryptic barriers to accurately identify reproductive units, and points to the need for local management of anadromous perch.

中文翻译：

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溯河波罗的海鲈鱼（Perca fluviatilis）的繁殖归巢和精细遗传结构

研究溯河波罗的海鲈鱼的种群动态（Linnaeus），我们研究了三个靠近（<50 km）种群的迁徙行为（到达产卵地点）和种群结构（遗传结构和分化）。产卵迁移持续 32-80 天，无源集成应答器标签 (PIT-tag) 数据表明溯河鲈鱼表现出生殖归巢。尽管基因流动水平较低（3%–5%），但种群还是有差异的，并且随着地理距离的增加，差异也会增加。这种精细的空间结构很可能，至少部分地，可以通过归巢行为来解释。对时间流内子结构的分析产生了不确定的结果，因此需要进一步的研究来评估这一点。综合起来，我们的研究结果强调了溯河鲈鱼精细遗传结构的潜力，并表明多种机制，如距离隔离、归巢和繁殖时间可能有助于这种模式。这说明了考虑隐蔽障碍以准确识别生殖单位的重要性，并指出需要对溯河鲈鱼进行局部管理。