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Report2007

Diet differentiation in three species of juvenile Pacific salmon (Oncorhynchus spp.) in estuarine tidal channels and laboratory experiments

Magnhagen, Carin; Northcote, Thomas G; Gregory, Robert S

Abstract

Enclosure experiments were performed in Fraser river estuary tidal channels to study the diet of juvenile pink, chum, and chinook salmon, when species were held alone and together. The aim of the study was to see whether the species were utilizing the same resources and if there was a potential for food competition in the tidal channels. The diet overlap between the species was high in 1986, comparing all three species, but in 1989, when only chum and chinook were present in the estuary, the overlap was lower. In both years differences in diet could be recognized. Pink fed mainly on harpacticoid copepods. This was also the most common prey item for the other species, but chum ate also other benthic species and chinook fed more on adult insects did the others. An aquarium experiment studying prey utilization in chum and chinook, separate and together, gave similar results as the field enclosures, with chinook taking more surface prey than did chum when kept together and chum eating more of small Daphnia

Published in

Canadian Technical Report of Fisheries and Aquatic Sciences
2007, number: 2758
Publisher: Department of Fisheries and Oceans, Canada