Expantion patterns of Chinook salmon in trans-national pacific rivers at Patagonia, Argentina

DI PRINZIO, C.Y.; CASAUX, R.J.

Mar del Plata

Conferencia; 2nd World Conference on Biological Invasions and Ecosystem Functioning; 2011

Grupo de Investigación y Educación en Temas Ambientales (GrIETA)

The presence of the Chinook salmon (Oncorhynchus tshawytscha), in trans-national Pacific rivers at Patagonia (Argentina) has been documented since 1980, concurrently with the expansion of the aquaculture activities in Chile. In order to understand the patterns of distribution of this species at northwest Chubut we initially focused our studies at the Futaleufú River(43°08´S; 71°35´W). During sampling performed from January to May (2010 and 2011) we carried out censuses by snorkeling to determine the presence of the Chinook salmon at different sections of the river.  As a result, 50 individuals were caught, which were measured, weighted and sexed. We took tissue samples for posterior DNA analyses and collected scales and otoliths for ecotype and age determination. The comparison of our information with that obtained previously at the Futaleufú River indicated that the individuals has been increased in number, length and mass as revealed in records from 2000 to the 2011. Recently, we confirmed the presence of the Chinook salmon at the Percy stream (42°59´S; 71°29´W), a tributary of the Futaleufú river. In this work we discuss population attributes related with ecotype and age. The establishment of Chinook salmon populations in the region appears to be an ongoing process. In consequence, to document this process in real time is an opportunity to evaluate risks associated Chinook salmon expansion.