Feeding strategy of the exotic Rainbow trout (Oncorhynchus mykiss) at low order Patagonian streams

DI PRINZIO, C.Y.; MISERENDINO, M.L.; CASAUX, R.J.

FISHERIES MANAGEMENT AND ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013 p. 415 - 425

0969-997X

During 2005-2006 we studied the dietary composition and the feeding strategy of the rainbow trout Oncorhynchus mykiss (Walbaum) at two low order Patagonian streams. Benthic macroinvertebrate availability was estimated at both riffles and pools. Fish stomach contents were examined to determine prey richness and diversity, prey electivity, food-niche width, and the feeding strategy employed by trout along the year. Availability of benthos varied seasonally, Ephemeroptera, Trichoptera, Plecoptera and Diptera species dominated in samples. Rainbow trout diet was composed mainly of benthic macroinvertebrates, followed by terrestrial insects, fish, algae and plants. Different trout size-classes segregated the use of food resources to reduce the predation pressure. Elected preys included organisms displaying no to high mobility. A high feeding plasticity allows trout to buffer changes in food availability by switching from a specialized to a generalized feeding behaviour. Consequently, trout may exploit abundant but temporary food resources opportunistically, which would explain their marked expansion in Patagonian environments.