Anyone who was in France in the summer of 2018 can attest to the searing temperatures that swept the country. From north to south, the nation experienced the second hottest summer since records began. Whilst children played in lakes and the sea to cool off, the shellfish producers of Étang de Thau could only watch as their oysters and mussels perished at the hands of malaïgue – a period of sustained high temperatures and little wind. 

The ocean has always been a highly dynamic environment, with its ever-changing conditions presenting challenges to aquaculturalists. However, thanks to human-induced climate change and continuing carbon emissions, events like malaïgue may become more regular occurrences, bringing with them new disease-related challenges.

As every aquaculturalist knows, temperature plays a major role in the growth and health of aquatic species. Certainly, higher temperatures are typically related to higher energetic requirements and demand for food. In an interesting twist, finfish can find their hunger suppressed when held at the upper end of their thermal tolerance for too long – even though their metabolic demands continue to rise. Malnourished fish make for unhealthy fish, which makes for a more stressed and susceptible animal.

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This story was written for - and can be read in full at - The Fish Site.

Header Image Credit: Lumière des Amoutous by Laurent Sauvebois (CC BY-NC-ND 2.0)