Atlantic salmon Salmo salar aquaculture in Tasmania faces increasing challenges due to climate-driven shifts in environmental conditions, particularly combined elevated water temperatures and reduced dissolved oxygen (DO) levels. This study integrates findings from two complementary analyses investigating production biology and molecular responses of Atlantic salmon exposed to suboptimum conditions ( simulated summer: 19°C and 80% DO), followed by a recovery phase ( simulated autumn: 15°C and 100% DO). W e assessed feed intake and growth performance over simulated summer and autumn in two seawater size groups (~420 g and ~2600 g) from the same cohort and genetic background . A focus was placed on specific growth rate (SGR) phenotypes, whole body chemical composition, alongside transcriptomic profiling of liver and white muscle tissues in commercially highly relevant size
The analysis showed significant differences in growth performance (FI, SGR, FCR, FE) across size groups and between suboptimum condition and recovery periods, with larger fish being more adversely affected (Figure 1). Machine learning analyses supported these findings, highlighting size-dependent vulnerability and recovery potential.
Transcriptomic biomarker discovery approaches identified genes , pathways and biological processes associated with growth resilience and impairment in the large fish group (>2 kg) following suboptimum simulated suboptimum summer and recovery autumn (Figure 2).
Using a translational approach, t his study leveraged novel insights into growth-dependent molecular strategies with practical mitigation approaches for managing combined thermal and dissolved oxygen stress in farmed Atlantic salmon.