Susceptibility of native perca (Percichthys trucha) and exotic rainbow trout (Oncorhynchus mykiss) to high temperature in Patagonia: different physiological traits and distinctive responses

Abstract

The aim of this work was to explore for the existence of a physiological basis for the apparent exclusion of salmonid fish from the littoral zone of lakes in Patagonia in response to increasing water temperature, to the benefit of the native perca (Percichthys trucha). We conducted experiments on the thermal preferences of juvenile perca and rainbow trout collected in three sites of Northern Patagonia. We characterized the relationship between preferred and acclimation temperature (PT, AT) for perca and trout and analyzed between-sites variations in PTs. Both species responded with increasing PT to higher AT, but with differences in overall PT for perca from different sites (lower PTs for fish from cooler lake). In general, rainbow trout displayed lower PT and a narrower range of PT than perca. Our results provide the first comparative view of PTs of one important.