Trophic ecology of nonanadromous rainbow trout in a post-glacial lake system: partial convergence of adfluvial and fluvial forms

• Main Authors: Arostegui, Martin Christopher, Quinn, Thomas P.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2017
• Subjects: Arctic; Glacial Lake; Sockeye; Varden; Alaska
• Online Access: http://hdl.handle.net/1807/89233; http://www.nrcresearchpress.com/doi/abs/10.1139/cjz-2017-0201

The rainbow trout (Oncorhynchus mykiss Walbaum, 1792) is one of many salmonid species exhibiting a gradient of life histories including fluvial (stream-resident), anadromous (ocean-migrant), and adfluvial (lake-migrant) forms, the last of which is less extensively studied than the other two. Our goal was to determine the extent of diet segregation between fluvial and adfluvial rainbow trout. We collected stomach content and stable isotope data on rainbow trout sampled in stream and lake habitats in a southwestern Alaska watershed during summer, and compared them to data on sympatric stream- and lake-specialist char species (Salvelinus malma Walbaum, 1792 and S. alpinus Linnaeus, 1758, respectively). Rainbow trout in streams fed largely on aquatic insects while those in the lake ate primarily benthic snails and amphipods. The trophic segregation of stream-resident and lake-migrant rainbow trout mirrored but was less extreme than the divergence of lotic Dolly Varden (S. malma) and lentic Arctic char (S. alpinus) in the same system. Spawning sockeye salmon (Oncorhynchus nerka Walbaum, 1792) provided a nutrient subsidy in the form of eggs that supported rainbow trout in both stream and lake (littoral) habitats, causing their isotopic signatures to converge. This study augments knowledge of partial migration and trophic divergence within populations. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.