Response of Rainbow Trout to Different Food Web Structures in Northern Patagonia: Implications for Growth, Bioenergetics, and Invasiveness.

JUNCOS, ROMINA; MILANO, DANIELA; MACCHI, PATRICIO JORGE; ALONSO, MARCELO FABIÁN; VIGLIANO, PABLO HORACIO

TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY

AMER FISHERIES SOC

Año: 2011 vol. 140 p. 415 - 428

0002-8487

Rainbow trout (Oncorhynchus mykiss) have successfully colonized almost all available water bodies in Patagonia. Introduction and restocking practices have taken place since the beginning of the 20th Century without prior consideration of differences between environments in terms of fish community composition and trophic food web structure. We assessed how observed growth, growth efficiency, production and biomass of rainbow trout populations from four Patagonian lakes are influenced by food web structure and prey quality, and the growth strategies adopted by this species in response to environmental differences. Fish communities vary in terms of species composition and dominance. Bioenergetic simulations showed that size and growth patterns of rainbow trout varied between lakes, mainly due to dietary differences. Fewer and lower quality food items led to low growth efficiency and stunted growth, while a more diverse and higher energy diet base led to higher growth efficiencies and sizes. Rainbow trout density, production and biomass were higher in the larger, more structurally complex lakes, although in the smallest one, production values were comparable to that of a lake twice its size. This study provides comparative evidence of the high plasticity of rainbow trout, which, through the adoption of different growth strategies, are able to successfully colonize environments where diet bases range widely in quality.