Growth of juvenile steelhead Oncorhynchus mykiss under size-selective pressure limited by seasonal bioenergetic and environmental constraints

Journal of Fish Biology
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Abstract

Increased freshwater growth of juvenile steelhead Oncorhynchus mykiss improved survival to smolt and adult stages, thus prompting an examination of factors affecting growth during critical periods that influenced survival through subsequent life stages. For three tributaries with contrasting thermal regimes, a bioenergetics model was used to evaluate how feeding rate and energy density of prey influenced seasonal growth and stage-specific survival of juvenile O. mykiss. Sensitivity analysis examined target levels for feeding rate and energy density of prey during the growing season that improved survival to the smolt and adult stages in each tributary. Simulated daily growth was greatest during warmer months (1 July to 30 September), whereas substantial body mass was lost during cooler months (1 December to 31 March). Incremental increases in annual feeding rate or energy density of prey during summer broadened the temperature range at which faster growth occurred and increased the growth of the average juvenile to match those that survived to smolt and adult stages. Survival to later life stages could be improved by increasing feeding rate or energy density of the diet during summer months, when warmer water temperatures accommodated increased growth potential. Higher growth during the summer period in each tributary could improve resiliency during subsequent colder periods that lead to metabolic stress and weight loss. As growth and corresponding survival rates in fresh water are altered by shifting abiotic regimes, it will be increasingly important for fisheries managers to better understand the mechanisms affecting growth limitations in rearing habitats and what measures might maintain or improve growth conditions and survival.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Growth of juvenile steelhead Oncorhynchus mykiss under size-selective pressure limited by seasonal bioenergetic and environmental constraints
Series title Journal of Fish Biology
DOI 10.1111/jfb.13078
Volume 89
Issue 3
Year Published 2016
Language English
Publisher Fisheries Society of the British Isles
Publisher location London
Contributing office(s) Coop Res Unit Seattle
First page 1720
Last page 1739
Country United States
State Washington
Other Geospatial Skagit River Basin