Quantitative Genetics of Thermal Tolerance in Atlantic salmon of farmed, wild and hybrid origin

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The applied study involves acute temperature stress of Atlantic salmon. In the study, young-of-the-year fish will be exposed to increasing water temperature until loss of righting response (LRR) occurs. Expected duration of the experiment is max. 120 min, whereby the experiment starts with non-stressful ambient water temperature that increases slowly. The distress experienced may be categorised as temporary mild temperature stress.

The study species (Atlantic salmon) is a homoeothermic fish. The metabolism of homoeothermic fishes is a function of the water temperature, whereby fish can adjust their metabolism (i.e., acclimate) within species-specific temperatures ranges. However, within these ranges, acclimation only occurs until the temperature-change rate and magnitude exceeds the rate and magnitude a species can acclimate to. When the temperature-rate change exceeds the possible acclimation rate, LRR occurs because the water temperature exceeds the thermal requirements to maintain a normal physiological state that allows for an organised locomotor activity.

This study investigates increase of both average temperature and heat-wave frequency, while accounting for plastic acclimation effects, which may be one of the most realistic climate change scenarios. Furthermore, we want to investigate general thermal and acute heat-stress tolerance among domesticated, wild, and domesticated-wild hybrid Atlantic salmon in order to determine gene flow effects on mean trait expression. This study will provide important knowledge towards understanding the consequences of farmed salmon introgressing wild rivers, and how this may be affected by climate change.