Volume 45 - Number 2 - 2010
Article

Evidence of microhabitat overlap between juvenile of introduced salmon Oncorhynchus tshawytscha and the native fish Trichomycterus areolatus in the Allipén River, Chile

Pamela V. Vargas¹, Iván Arismendi^2,3, Gladys Lara¹, Javier Millar¹ y Santiago Peredo¹

¹Escuela de Ciencias Ambientales, Facultad de Recursos Naturales, Universidad Católica de Temuco, Casilla D-15, Temuco, Chile

²Escuela de Graduados, Facultad de Ciencias Forestales, Universidad Austral de Chile, Casilla 567, Valdivia, Chile

³USGS Forest and Rangeland Ecosystem Science Center, Aquatic Ecology Laboratory, 3200 SW Jefferson Way, Corvallis, Oregon 97331, Estados Unidos

E-mail: pvargasaraya@gmail.com

Introduced juvenile Chinook salmon (Oncorhynchus tshawytscha) have been found co-occurring with native fishes in the Allipén River, Chile. Due to this co-occurence, the microhabitat use, microhabitat preferences, and overlap between juvenile Chinook salmon and the native catfish, Trichomycterus areolatus, were examined during the summer and fall of 2007-2008. Microhabitat preferences and overlap between juvenile Chinook salmon and the native catfish were determined using the Instream Flow Incremental Methodology and the Pianka´s index. Juvenile Chinook salmon and the native catfish microhabitat preferences varied seasonally showing a high degree of similarity and overlap between the species (higher than 80%). The results suggest the risk of negative interactions and interactive segregation over habitat processes between juvenile Chinook salmon and native catfish. As a consequence, the Chinook salmon invasion may threaten the stability of native catfish populations at Allipén River

Key words: Biological invasions, co-occurrence, negative interactions, interactive segregation, temperate ecosystems

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