The intersection of thermal hysteresis and river-specific thermal regimes: Effects on thermal aggregation thresholds in juvenile Atlantic Salmon (Salmo salar) and brook trout (Salvelinus fontinalis)
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Date
2025-03
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University of New Brunswick
Abstract
In summer of 2021, 2022, and 2023, underwater cameras were used to observe the onset of behavioural thermoregulation by juvenile Atlantic salmon (Salmo salar) in the relatively cool Restigouche River, NB, and by juvenile salmon and brook trout (Salvelinus fontinalis) in the warmer Little Southwest Miramichi River, NB. This thesis aimed to determine if juvenile salmon and brook trout aggregated at various temperatures throughout the summer. If so, could the variation be explained by a thermal hysteresis model? Furthermore, whether the aggregation onset thresholds differ for juvenile salmon in each river was investigated.
It was determined that brook trout aggregated at a range of temperatures throughout both summers; however, the thermal hysteresis model could not explain the variation. Aggregations of juvenile salmon were not observed in the Miramichi, but aggregations in the Restigouche occurred in both years at various temperatures, and aggregations in 2022 strongly supported the thermal hysteresis model.