Dietary analysis of wild and hatchery juvenile Chinook salmon (Oncorhynchus tshawytscha) in the Fraser River estuary reveals differences in ontogenetic shifts
department or school: Forestry, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Roper, Paige
issued: 2025-11-27T17:30:18Z
issued: 2025
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The Fraser River is the major producer of Pacific salmon (Oncorhynchus spp.) in Canada with millions of juveniles out-migrating through its estuary each year. Estuaries provide critical rearing habitat for juveniles, in particular Chinook salmon (O. tshawytscha), which can reside in estuaries for several weeks. The diet of juvenile Chinook salmon in this habitat is a crucial component of their early development and survival. In 2021 and 2022, I examined size, stomach contents, and stomach fullness of 142 juvenile Chinook salmon of wild and hatchery origin from eelgrass habitat at Roberts Bank (Fraser River estuary). I examined an additional 37 wild Chinook salmon from marsh and sandflat habitats. GSI analyses revealed 83% of all wild fish originated from lower Fraser River populations and PBT analyses revealed 91% of all hatchery fish originated from lower Fraser River populations. In eelgrass habitat, hatchery fish were on average 6.1 mm (~7%) longer than wild fish. Stomach fullness increased with fish size and was ~34% higher in wild fish compared to hatchery fish. Wild fish trended towards fuller stomachs in marsh habitat and emptier stomachs in sandflat habitat compared to those in eelgrass habitat. Stomach content analysis suggested size and time of year were indicators of juvenile Chinookâs transition to a primarily piscivorous diet, which was seen in wild fish with fork lengths as small as 63 mm. Liver and dorsal muscle samples from 130 wild and hatchery Chinook salmon captured in eelgrass habitat were analyzed for Î´Â¹âµN and δ¹³C revealing overlapping trophic ellipses. Wild fish had greater niche widths compared to hatchery fish and tended to consume higher-quality prey and utilized more diverse habitats compared to hatchery fish highlighting the importance of conserving eelgrass and marsh habitats and the prey they support. To improve foraging competency of hatchery fish in estuaries, naturalization of feeding systems in rearing facilities should be imp…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/93042
note: DIETARY ANALYSIS OF WILD AND HATCHERY JUVENILE CHINOOK SALMON (ONCORHYNCHUS TSHAWYTSCHA) IN THE FRASER RIVER ESTUARY REVEALS DIFFERENCES IN ONTOGENETIC SHIFTS by Paige Roper A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in The Faculty of Graduate and Postdoctoral Studies (Forestry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) November 2025 © Paige Roper, 2025 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled: DIETARY ANALYSIS OF WILD AND HATCHERY JUVENILE CHINOOK SALMON (ONCORHYNCHUS TSHAWYTSCHA) IN THE FRASER RIVER ESTUARY REVEALS DIFFERENCES IN ONTOGENETIC SHIFTS submitted by Paige Roper in partial fulfilment of the requirements for the degree of Master of Science in Forestry Examining Committee: Dr. Scott Hinch, Professor, Forestry, UBC Supervisor Dr. Brian Hunt, Associate Professor, Institute for the Oceans and Fisheries, UBC Supervisory Committee Member Dr. Tara Martin, Professor, Forestry, UBC Supervisory Committee Member Dr. Evgeny A. Pakhomov, Professor, Institute for Oceans and Fisheries, UBC Additional Examiner iii Abstract The Fraser River is the major producer of Pacific salmon (Oncorhynchus spp.) in Canada with millions of juveniles out-migrating through its estuary each year. Estuaries provide critical rearing habitat for juveniles, in particular Chinook salmon (O. tshawytscha), which can reside in estuaries for several weeks. The diet of juvenile Chinook salmon in this habitat is a crucial component of their early development and survival. In 2021 and 2022, I examined size, stomach contents, and stomach fullness of 142 juvenile Chinook salmon of wild and hatchery origin from eelgrass habitat at Roberts Bank (Fraser River estuary). I examined an additional 37 wild Chinook salmon from marsh and sandflat habitats. GSI analyses revealed 83% of all wild fish originated from lower Fraser River p…
has type: Thesis/Dissertation
date issued: 2026-05
is shown at: 10.14288/1.0450883
language: eng
degree discipline: Forestry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Hinch, Scott G.
type: Text
identifier URI: http://hdl.handle.net/2429/93042