Feeding strategy of the non-native rainbow trout, Oncorhynchus mykiss, in low-order Patagonian streams.

DI PRINZIO C.; MISERENDINO L.; CASAUX R,

FISHERIES MANAGEMENT AND ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013 vol. 20 p. 414 - 425

0969-997X

Abstract The dietary composition and feeding strategy of rainbow trout, Oncorhynchus mykiss (Walbaum), in twolow-order Patagonian streams were studied. Benthic macroinvertebrate availability was estimated in both riffles andpools. Fish stomach contents were examined to determine prey richness and diversity, prey electivity, food-nichewidth, and the feeding strategy employed by trout throughout the year. Availability of benthos varied seasonally withEphemeroptera, Trichoptera, Plecoptera and Diptera species dominating. Rainbow trout diet was composed mainly ofbenthic macroinvertebrates, followed by terrestrial insects, fish, algae and plants. Different trout size classes segregatedthe use of food resources to reduce predation pressure. Elected prey included organisms displaying no to highmobility. A high feeding plasticity allows trout to buffer changes in food availability by switching from a specialisedto a generalised feeding behaviour. Consequently, trout may exploit abundant but temporary food resourcesopportunistically, which would explain their marked expansion in Patagonian environments.