Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperatures.

Hnytka, Sarah ORCID: https://orcid.org/0009-0001-1950-8272; Rosenfeld, Jordan ORCID: https://orcid.org/0000-0002-5827-9740 et Enders, Eva C. ORCID: https://orcid.org/0000-0003-2103-0359 (2025). Determining the upper thermal tolerance of Athabasca Rainbow Trout (Oncorhynchus mykiss) across naturally varying stream temperatures. FACETS , vol. 10 . pp. 1-11. DOI: 10.1139/facets-2023-0241.

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Résumé

Stream temperature is a key driver of physiological function in ectothermic fish, and fish have clear upper and lower limits to thermal habitat use. Stream temperature increases from climate change are a major threat to coldwater taxa like Athabasca Rainbow Trout (Oncorhynchus mykiss), listed as Endangered under Canada's Species at Risk Act. To better understand their vulnerability to climate change and prioritize recovery locations, Athabasca Rainbow Trout were collected in August 2021 from three streams in the upper Athabasca River, Alberta, Canada, across a gradient of thermal regimes ranging from cold to warm. Individual thermal tolerance was measured using two physiological metrics: agitation temperature (T_ag) and critical thermal maxima (CT_max) using a portable streamside laboratory. T_ag is a behavioural indicator of a thermal avoidance threshold, whereas CT_max is a physiological response that can be interpreted as the upper thermal limit where long term survival is reduced. Results provide strong evidence that CT_max is a plastic metric in Athabasca Rainbow Trout; however, T_ag is not. This suggests that Athabasca Rainbow Trout demonstrate some thermal plasticity in terms of CT_max, yet the lack of plasticity in T_ag indicates potential limitations in their adaptability to warming stream temperatures.

Type de document:	Article
Mots-clés libres:	critical thermal maxima; agitation temperature; thermal physiology; Athabasca Rainbow Trout; streamside laboratory; climate change
Centre:	Centre Eau Terre Environnement
Date de dépôt:	14 juill. 2025 14:20
Dernière modification:	14 juill. 2025 14:20
URI:	https://espace.inrs.ca/id/eprint/16518

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