Biological Invasions

, Volume 13, Issue 1, pp 203–213 | Cite as

Discrimination between farmed and free-living invasive salmonids in Chilean Patagonia using stable isotope analysis

  • V. Schröder
  • Carlos Garcia de Leaniz
Original Paper


In Chilean Patagonia relatively pristine aquatic environments are being modified by the introduction of exotic salmonids, initially through their deliberate release for sport fishing since the early twentieth century, and more recently via the accidental escape from fish farms. There is therefore a need to reliably distinguish between naturally reproducing and fugitive salmonids associated with the Chilean salmonid farming industry, the second largest in the world. We tested the ability of stable isotope analysis (SIA) and analysis of scale growth profiles to discriminate between farmed and free-living salmonids sampled around the Island of Chiloé. Juvenile Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) from aquaculture facilities were significantly more enriched in δ15N and lipid-corrected δ13C than river-caught individuals. Scale growth slopes during the first year in freshwater were significantly higher in farmed than in wild-caught rainbow trout, indicating faster somatic growth under hatchery conditions. Stable isotopes analysis classified 94% of juvenile Atlantic salmon and rainbow trout to their correct farm or free-living groups. Our results, therefore, can help to elucidate the origin and spread of exotic invasive salmonids in Chile, and address one of the biggest threats to native freshwater fishes in Patagonia and other temperate zones of the Southern Hemisphere.


Stable isotope analysis Invasive species Salmonids Aquaculture 



We thank Kyle Young, Jane MacDonald, Paul Howes, Ben Perry, Gabriel Orellana and Jessica Stephenson for collecting the samples in Chile. Iain Robertson, Kath Ficken and Neil Loader provided assistance with isotopic analysis and Laura Roberts and Gethin Thomas helped with sample processing. We are also grateful to Alaric B. Smith, Sonia Consuegra, Gonzalo Gajardo, and an anonymous referee for useful comments on an earlier version of the manuscript. Funding for this study was provided by a DEFRA Darwin Initiative ‘Reducing the Impact of Exotic Aquaculture on Chilean Aquatic Biodiversity (Grant No. 162/15/020; to CGL and GG.


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© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  1. 1.Department of Pure and Applied Ecology, Institute of Environmental SustainabilitySwansea UniversitySwanseaUK

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