Study of the diet of rainbow trout (Oncorhynchus mykiss) in the Pehuenche Valley (Malargüe, Mendoza, Argentina)

Abstract

Salmonids, as invasive alien species, affect endemic species through predation, habitat occupation, and competition for trophic resources. In the Pehuenche Valley, their habitat overlaps with that of the amphibian Alsodes pehuenche, a severely threatened microendemic species. This study focuses on analyzing the diet of the salmonid Oncorhynchus mykiss as a basis for understanding its interaction with the threatened amphibian. Methods included obtaining stomach contents from trout and determining diet items in the laboratory. The results indicate that O. mykiss feeds predominantly on macroinvertebrates belonging to 10 orders. The most abundant orders are Diptera, followed by Coleoptera and Trichoptera. O. mykiss takes advantage of a variety of prey available in its environment, making it an important predator within aquatic ecosystems. This baseline study provides information necessary to advance understanding of ecological interactions in high-altitude wetlands and support conservation measures to protect threatened native species.