Ecological Traits and Fishery of the Upper Limay River: A Key System for Salmonids in the Andean North Patagonia

The Limay River is one of the most relevant fluvial systems of the northern Andean Patagonia, being the only effluent of Lake Nahuel Huapi. Since the last third of the twentieth century, its course has been fragmented by the construction of dams. These human-induced alterations have modified the dynamics of the fish populations. Herein, we describe the ecological and functional characteristics of the upper Limay that rises from Nahuel Huapi Lake and mouths into the Alicurá Reservoir. The fish fauna is composed of four introduced salmonids and four native species. The distribution patterns of these species are not homogeneous along the river. The fish assemblage is dominated by Oncorhynchus mykiss and Salmo trutta showing different life tactics from strictly resident to migratory forms entering the lentic environments for reproduction and show very different abundances. Native species are locally restricted. Only salmonids are found in the tributaries. The river, its tributaries and secondary habitats, activated in high water periods, constitute an excellent spawning and breeding habitat for salmonids, which, added to the connectivity between lakes suggest the potential occurrence of meta-populations. The river system supports an important sport fishery, focused on O. mykiss and S. trutta, which attracts national and international anglers who make a fundamental contribution to the regional economy.