Stomach contents were collected and analysed from 22 bull trout Salvelinus confluentus at the edge of the Chilko Lake and Chilko River in British Columbia, Canada, during spring outmigration of sockeye salmon Oncorhynchus nerka smolts. Twenty of the 22 (>90%) stomachs contained prey items, virtually all identifiable prey items were outmigrant O. nerka smolts and stomach contents represented a large portion (0·0-12·6%) of estimated S. confluentus mass. The results demonstrate nearly exclusive and intense feeding by S. confluentus on outmigrant smolts, and support recent telemetry observations of high disappearance rates of O. nerka smolts leaving large natural lake systems prior to entering high-order unregulated river systems.
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http://dx.doi.org/10.1111/jfb.12567 | DOI Listing |
Conserv Physiol
April 2024
Fisheries and Oceans Canada, Science Branch, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
The amount of time that juvenile salmon remain in an estuary varies among and within populations, with some individuals passing through their estuary in hours while others remain in the estuary for several months. Underlying differences in individual physiological condition, such as body size, stored energy and osmoregulatory function, could drive individual variation in the selection of estuary habitat. Here we investigated the role of variation in physiological condition on the selection of estuarine and ocean habitat by sockeye salmon () smolts intercepted at the initiation of their 650-km downstream migration from Chilko Lake, Fraser River, British Columbia (BC).
View Article and Find Full Text PDFJ Morphol
January 2023
Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, USA.
Sockeye salmon, Oncorhynchus nerka, are anadromous, semelparous fish that breed in freshwater-typically in streams, and juveniles in most populations feed in lakes for 1 or 2 years, then migrate to sea to feed for 2 or 3 additional years, before returning to their natal sites to spawn and die. This species undergoes important changes in behavior, habitat, and morphology through these multiple life history stages. However, the sensory systems that mediate these migratory patterns are not fully understood, and few studies have explored changes in sensory function and specialization throughout ontogeny.
View Article and Find Full Text PDFPLoS One
August 2022
Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University, Corvallis, Oregon, United States of America.
We investigated the cumulative effects of predation by piscivorous colonial waterbirds on the survival of multiple salmonid (Oncorhynchus spp.) populations listed under the U.S.
View Article and Find Full Text PDFR Soc Open Sci
March 2021
Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, Canada.
Predation risk for animal migrants can be impacted by physical condition. Although size- or condition-based selection is often observed, observing infection-based predation is rare due to the difficulties in assessing infectious agents in predated samples. We examined predation of outmigrating sockeye salmon () smolts by bull trout () in south-central British Columbia, Canada.
View Article and Find Full Text PDFConserv Physiol
March 2021
Fisheries and Oceans Canada, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
Long-distance migrations can be energetically demanding and can represent phases of high mortality. Understanding relationships between body condition and migratory performance can help illuminate the challenges and vulnerabilities of migratory species. Juvenile anadromous sockeye salmon () may migrate over 1000 km from their freshwater nursery habitats to estuary and ocean feeding grounds.
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