Chinook salmon (Oncorhynchus tshawytscha, Walbaum 1792) in the Beagle Channel, Tierra del Fuego: the onset of an invasion
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In this paper we provide the first report of the presence of exotic Chinook salmon (Oncorhynchus tshawytscha) in two rivers off the Beagle Channel, Lapataia and Ovando, in southern Tierra del Fuego. We also confirm that successful reproduction occurred in the fall of 2007, as we captured yearlings in freshwater. Scale pattern analyses of adult fish caught were all of the “stream” ecotype, with ages ranging between 3 and 5 (average 4.2 year). Stable isotope analysis of Ovando-Lapataia Chinook population indicates general patterns consistent with those of other populations in the region, but characteristically enriched levels of C indicates a distinct ocean feeding location as compared to Atlantic populations in the Santa Cruz River. Two different haplotypes, one identical to the unique haplotype of the Caterina River population, were found in the Ovando-Lapataia rivers, providing partial evidence for some level of contemporary segregation between these two populations. As an exotic species, Chinook salmon have been able to use the ocean as a waterway to rapidly colonize new habitats both in New Zealand and in several Pacific and Atlantic river basins of continental Patagonia. This record expands the known distribution of this species in Patagonia further south and into the Island of Tierra del Fuego. Its presence in the Beagle Channel creates the conditions for its expansion to a significant collection of new rivers, as well as to adjacent marine areas in and around the Southern Fuegian Channels. Our results provide support to the idea that, in practice, no district of Patagonia is sheltered from the colonization by invasive anadromous Salmonids.
KeywordsChinook salmon Beagle Channel Patagonia Exotic anadromous salmon
This work was supported by a specific grant from Argentinean Association of National Parks (APN), and grants from National Council of Scientific and Technological Research (CONICET), Federal Council of Science and Technology (COFECyT) and the National Agency for the Promotion of Science and Technology (FONCyT). We would like to thank Dr. F. Botto and Dr. O. Iribarne for SIA analysis, Park Rangers of the National Park Tierra del Fuego for providing pictures and samples of the specimens and helping with the surveys, Facundo Llompart and Mariela Victorio for helping with the sampling, Carlos Luizón for assistance in the early identification of the species, Rodolfo Iturraspe for providing data and a map of the different river basins and Sheryl Macnie for improving the English of the manuscript.
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