People: Miguel Pascual, Carla Riva Rossi, Javier Ciancio, Billy Ernst Elizalde, Eduardo Aedo, Antonio Gagliardini, Florencia Botto, Oscar Iribarne, Ana Liberoff.

The occurrence of different species in river basins throughout Patagonia is used to identify variables and processes that critically influence the establishment and dispersal of exotic anadromous salmonids, also anticipating some of their potential impacts. A particularly relevant issue related to the study of exotic species is the identification of variables and processes that determine the establishment and colonization of new environments. It has high applied value, for it can provide some clues to understand the invasiveness of particular species and the invasibility of particular communities.

We use anadromous salmonids of southern Patagonia as a model to study the process of establishment and dispersal of exotic species. We regard the occurrence of five exotic species throughout a collection of river basins in the region as a natural experiment to identify variables and processes of species and receiving communities shaping the process of invasion.

Whereas salmonids breed in freshwater, anadromous forms utilize the ocean as a prime feeding ground and as a dispersal waterway. It is in the ocean where they capture most of their energy and experience most of their somatic growth; as much as 99% of the body weight of anadromous Salmonids can be derived from marine nutrients. The ocean is also the matrix connecting different reproductive units and the path to colonizing new river basins.

We are analyzing the general physical and biological characteristics of the portions of the southern Atlantic and Pacific oceans surrounding Argentine and Chilean Patagonia to identify areas with favorable conditions for anadromous Salmonids, to characterize receiving marine communities, and to establish the limits to their distribution and most likely migration paths.

We hope to generate increasingly more specific hypotheses about the distribution and trophic behavior of different species of anadromous salmonids present in the region. In view of the growth and geographic expansion of salmon net pen aquaculture in Chile, we hope that such information could help to build regional scenarios for the acclimatization of salmonids, as well as of their ecological, social and economic impacts.

Goals

Characterize historic and demographic processes associated to the colonization of new habitat by established species.

Evaluate the adjustment between the life cycle of different species and the characteristics of particular receiving environments through empiric and mechanistic habitat models.

Assess areas of actual and potential marine distribution for different species, including potentially interacting species.

Generate scenarios of regional distribution of anadromous species as a function of the geographic distribution of salmon aquaculture.

Estimate the magnitude of food intake by particular species and populations.

Some specific activities

Elaborate a worldwide data base on introduction events involving anadromous salmonids.

Reconstruct historic and demographic processes associated to the colonization of new areas by the analysis of the genetic architecture of established populations.

Assess critical habitat characteristics relevant for the life cycle of different species in different receiving environments.

Construct mechanistic habitat models to analyze the adjustment between species and receiving environments.

Generate a geographic information system containing catches and sightings, physical and biological oceanographic characteristics, distribution and overlap with interacting species.

Generate trophic hypotheses for different anadromous salmon species and populations through stable isotope analysis and stomach contents.

Bionergetic characterization and modeling to estimate reproductive investment and food consumption at age from observed growth and fecundity.