There has been a recent trend in Atlantic salmon (Salmo salar) aquaculture to stock large post-smolts to reduce fish health risk. While this practice has primarily been implemented to reduce disease potential, it may also enable management strategies to avoid temperature extremes that constrain the growing season in many regions. Depending on local temperature and initial fish size, large post-smolt stocking could enable grow-out to target market weights in less than a year, providing opportunity to circumvent predictable periods of superchill while accounting for heat stress. Such approaches may also need to account for greater uncertainty under climate change.
A process was developed to assess the potential of novel sites for Atlantic salmon grow-out under a changing climate. High resolution empirical temperature profiles were examined at three coastal locations around Nova Scotia, Canada. Functional growth days per season at locations and depths were identified using known temperature thresholds (Fig. 1). The thermal growth coefficient model was applied to calculate the stocking weight required to grow-out salmon, assuming superchill could be circumvented and growth ceased at high temperatures.
Preliminary results suggest that an approximately 1-kg salmon could grow to market size (5 kg) in less than a year in some areas that are typically considered unfavourable for aquaculture due to superchill. Warm water substantially reduced production, with no growth on up to 13 % of simulated stocked days due to heat stress events. The potential for novel sites and implications for stocking and effects of climate change are explored. The R package developed for the analysis can be installed from GitHub and applied to other regions of interest.