Document Type

Article

Journal/Book Title/Conference

North American Journal of Fisheries Management

Volume

16

Issue

3

Publisher

American Fisheries Society

Publication Date

1996

First Page

591

Last Page

599

DOI

10.1577/1548-8675(1996)016<0591:EODAOG>2.3.CO;2

Abstract

We monitored the diet and growth of stocked rainbow trout Oncorhynchus mykiss in two Utah reservoirs during 1986 and 1989–1990. For the first month after stocking, juvenile rainbow trout in both reservoirs fed extensively on large Daphnia spp. In East Canyon Reservoir where Daphnia were abundant, this pattern continued throughout the summer, fall, and winter. Growth of rainbow trout in East Canyon Reservoir was generally good throughout 1989–1990. In Causey Reservoir, where Daphnia were less abundant and smaller, rainbow trout fed progressively less on smaller Daphnia throughout the summer, fall, and winter, while other prey items (snails, aquatic insects, and algae) became more important. Bioenergetics simulations of patterns of rainbow trout growth suggest that consumption by rainbow trout was closely related to daphnid biomass. This index of zooplankton forage could be used to assess feeding conditions for zooplanktivorous salmonids in other systems.

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