Phenotypic stress response does not influence the upper thermal tolerance of male Atlantic salmon (Salmo salar)

• Published in: Journal of Thermal Biology
• Main Authors: Ignatz, Eric H., Zanuzzo, Fabio S., Sandrelli, Rebeccah M., Clow, Kathy A., Rise, Matthew L., Gamperl, A. Kurt
• Other Authors: Universidade Estadual Paulista (UNESP)
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier B.V. 2021
• Subjects: Atlantic salmon; Stress; Cortisol; Thermal tolerance; Climate change; Canada; Newfoundland; Salmo salar
• Online Access: http://hdl.handle.net/11449/218682; https://doi.org/10.1016/j.jtherbio.2021.103102

Mitigating the Impact of Climate-Related Challenges on Salmon Aquaculture (MICCSA) project Atlantic Canada Opportunities Agency Innovate NL Innovate PEI Graduate and Post-Doctoral Fellowship Fund AquaBounty Canada Somru Biosciences Center for Aquaculture Technologies Canada Huntsman Marine Science Centre Natural Sciences and Engineering Research Council of Canada (NSERC) Atlantic Canada Opportunities Agency: 781-9658-205222 Innovate NL: 5404-1209-104 Fish can be identified as either low responders (LR) or high responders (HR) based on post-stress cortisol levels and whether they exhibit a proactive or reactive stress coping style, respectively. In this study, male Atlantic salmon (Salmo salar) from 17 families reared at 9 degrees C were repeatedly exposed to an acute handling stress over a period of four months, with plasma cortisol levels measured at 1 h post-stress. Fish were identified as either LR or HR if the total Z-score calculated from their cortisol responses fell into the lower or upper quartile ranges, respectively; with intermediate responders (IR) classified as the remainder. Salmon characterized as LR, IR or HR were then subjected to an incremental thermal challenge, where temperature was raised at 0.2 degrees C day(-1) from their acclimation temperature (12 degrees C) to mimic natural sea-cage farming conditions during the summer in Newfoundland. Interestingly, feed intake remained high up to 22 degrees C, while previous studies have shown a decrease in salmon appetite after similar to 16-18 degrees C. After the first three mortalities were recorded at elevated temperature, a subset of LR and HR salmon were exposed to another acute handling stress event at 23.6 degrees C. Basal and post-stress measurements of plasma cortisol, glucose and lactate did not differ between stress response phenotypes at this temperature. In the end, the average incremental thermal maximum (ITMax) of LR and HR fish was not different (25.1 degrees C). In comparison, the critical thermal maximum ...