ORIGINAL RESEARCH article
Front. Mar. Sci.
Sec. Marine Biology
Volume 12 - 2025 | doi: 10.3389/fmars.2025.1662755
This article is part of the Research TopicFactors Influencing Diadromous Fish Migration and their Fitness ConsequencesView all articles
Between Oceans: Stepping-Stone Dispersal and the Pacific-to-Atlantic Expansion of Chinook Salmon Across Patagonia
Provisionally accepted
Carla Riva-Rossi1
Javier Ciancio1*
Daniel Gomez-Uchida2Miguel Pascual1Rodrigo Clarke3Pamela Quiroga1
Cecilia Di Prinzio1
Carolina Lázari4
John Carlos Garza5- 1National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
- 2Universidad de Concepcion, Concepción, Chile
- 3Fundación Anfibia, Río Gallegos, Argentina
- 4university of California, Santa Cruz, United States
- 5Southwest Fisheries Science Center, National Oceanic and Atmospheric Administration, Santa Cruz, United States
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Biological invasions are major drivers of biodiversity loss worldwide, and salmonid introductions represent one of the most transformative cases in the Southern Hemisphere. The rapid expansion of Chinook salmon (Oncorhynchus tshawytscha) across South America constitutes an unprecedented invasion, fueled by traits such as high migration capacity, straying rates, and genetic adaptability. In Patagonia, this spread is accelerating, yet the genetic and ecological processes underlying dispersal and colonization remain poorly understood. Here, high-resolution SNP panels were used to investigate the genetic origins of a recently established population in the De las Vueltas River (DLVR), an upper tributary of the Santa Cruz River draining into the Atlantic Ocean. Mixture analyses revealed strong affinities with naturalized populations from Chile's Aysén Region and minor contributions from neighboring Santa Cruz populations, indicating colonization via long-distance oceanic or trans-Andean dispersal, followed by secondary intrabasin expansion.These findings highlight the role of ocean connectivity, stepping-stone habitats, and leading-edge dispersal in enabling rapid range expansion. Within this framework, the Santa Cruz River basin emerges as a critical invasion hub, concentrating propagules from multiple lineages and facilitating multi-step dispersal into new Atlantic basins. The need to consider dispersal corridors and invasion hubs in managing the ecological and evolutionary impacts of Chinook salmon in South America is underscored.
Keywords: invasive species, anadromous fish, Ocean migration, leading-edge dispersal, River connectivity
Received: 09 Jul 2025; Accepted: 15 Sep 2025.
Copyright: © 2025 Riva-Rossi, Ciancio, Gomez-Uchida, Pascual, Clarke, Quiroga, Di Prinzio, Lázari and Garza. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Javier Ciancio, ciancio@cenpat-conicet.gob.ar
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