Invasive species with migratory behavior and complex life cycles represent a challenge for evaluating natal sites among individuals. Private and government-sponsored initiatives resulted in the successful introduction and naturalization of Chinook salmon (Oncorhynchus tshawytscha) throughout northern and southern Patagonia in South America. Migratory populations of Chinook salmon breed in fresh water, but spend most of their life feeding at sea, forming abundant populations in several watersheds draining into the southeast Pacific Ocean. We used single nucleotide polymorphisms combined with genetic structure and mixed-stock analyses to evaluate natal sites of Chinook salmon at sea caught in one estuary and two coastal locations compared to reference populations from breeding sites in fresh water. Firstly, Bayesian individual-assignment analyses revealed no genetic structure among adults caught off the coast of the Toltén River and migrating (maturing) adults caught in Toltén River estuary, suggesting they likely belong to a single population. Secondly, mixed-stock genetic analyses revealed that most Chinook salmon caught in one estuary and two coastal locations likely originated from spawners from the nearest river (86–96%). Contributions from distant watersheds to mixtures at sea decreased with increasing geographic distance. Our combined genetic evidence points strongly to homing among non-native Chinook salmon, whereby most adults return to breed to their natal river amid potentially long-distance migrations through the coast. Mixed-stock genetic analyses provide considerable potential to identify the population of origin of Chinook salmon mixtures caught off the coast. They also seem an appropriate proof of concept to assess homing versus dispersal and infer invasion pathways via long-distance migration.

具有迁徙行为和复杂生命周期的入侵物种是评估个体出生地的挑战。私人和政府赞助的倡议导致了奇努克鲑鱼的成功引进和归化（Oncorhynchus tshawytscha）遍布南美的巴塔哥尼亚北部和南部。奇努克鲑鱼的迁徙种群在淡水中繁殖，但大部分时间都在海上觅食，在排入东南太平洋的数个流域中形成了丰富的种群。我们将单核苷酸多态性与遗传结构和混合种群分析相结合，以评估与来自淡水繁殖场所的参考种群相比，在一个河口和两个沿海地点捕捞的奇努克鲑鱼的出生地点。首先，贝叶斯个体分配分析显示，在托尔滕河沿岸捕获的成年成年人和在托尔滕河河口捕获的成年移民（成年）没有遗传结构，这表明他们很可能属于单个种群。其次，混合种群遗传分析表明，大多数在一个河口和两个沿海地区捕捞的奇努克鲑鱼很可能是来自最近河道的产卵者（86-96％）。随着地理距离的增加，从远距离流域到海上混合气的贡献减少。我们综合的遗传证据强烈指出归巢中的非原生大马哈鱼，其中大多数成年人回到滋生他们的本命河流经之际海岸潜在的长途迁徙。混合种群遗传学分析提供了巨大的潜力，可以确定在沿海捕获的奇努克鲑鱼混合物的起源种群。它们似乎也是评估归巢与散布以及通过远距离迁移推断入侵途径的适当概念证明。