Chinook salmon (Oncorhynchus tshawytscha, Walbaum 1792) in the Beagle Channel, Tierra del Fuego: the onset of an invasion

FERNANDEZ, D.F.; CIANCIO, J.E; CEBALLOS, S.; RIVA ROSSI, C.M.; PASCUAL, M.A.

BIOLOGICAL INVASIONS

SPRINGER

Año: 2010

1387-3547

<!-- /* Font Definitions */ @font-face {font-family:Garamond; panose-1:2 2 4 4 3 3 1 1 8 3; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:647 0 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin-top:6.0pt; margin-right:0cm; margin-bottom:0cm; margin-left:0cm; margin-bottom:.0001pt; text-align:justify; mso-pagination:widow-orphan; text-autospace:none; font-size:12.0pt; font-family:Garamond; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:Garamond; color:black; mso-ansi-language:EN-US;} p.entry, li.entry, div.entry {mso-style-name:entry; margin-top:0cm; margin-right:0cm; margin-bottom:6.0pt; margin-left:27.2pt; text-align:justify; text-indent:-27.2pt; mso-pagination:widow-orphan lines-together; text-autospace:none; font-size:12.0pt; font-family:Garamond; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:Garamond; color:black; mso-ansi-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> In this paper we provide the first report ofthe presence of exotic Chinook salmon (Oncorhynchustshawytscha) in two rivers off the BeagleChannel, Lapataia and Ovando, in southern Tierradel Fuego. We also confirm that successful reproductionoccurred in the fall of 2007, as we capturedyearlings in freshwater. Scale pattern analyses ofadult fish caught were all of the ‘‘stream’’ ecotype,with ages ranging between 3 and 5 (average4.2 year). Stable isotope analysis of Ovando-LapataiaChinook population indicates general patterns consistentwith those of other populations in the region,but characteristically enriched levels of C indicates adistinct ocean feeding location as compared toAtlantic populations in the Santa Cruz River. Twodifferent haplotypes, one identical to the uniquehaplotype of the Caterina River population, werefound in the Ovando-Lapataia rivers, providingpartial evidence for some level of contemporarysegregation between these two populations. As anexotic species, Chinook salmon have been able to usethe ocean as a waterway to rapidly colonize newhabitats both in New Zealand and in several Pacificand Atlantic river basins of continental Patagonia.This record expands the known distribution of thisspecies in Patagonia further south and into the Islandof Tierra del Fuego. Its presence in the BeagleChannel creates the conditions for its expansion to asignificant collection of new rivers, as well as toadjacent marine areas in and around the SouthernFuegian Channels. Our results provide support to theidea that, in practice, no district of Patagonia issheltered from the colonization by invasive anadromousSalmonids