Heatwaves cause mass fish mortality in French ponds

Extreme heat and drought conditions in France have led to significant fish mortality and environmental distress in several ponds.

In the Meuse region, fishing has been prohibited at the Franchot ponds in Ancerville since late June. Local officials cited critical water level drops, rising temperatures, and decreased oxygenation, which have placed fish populations under severe thermal stress. Site manager Daniel Bayette noted that the ponds have turned green with duckweed, which prevents photosynthesis and further depletes oxygen levels.

Similarly, in the Côtes-d'Armor region, dozens of dead fish—estimated at approximately 100 kilograms—were discovered at the surface of the Trévé pond near Loudéac. Local fishing federation officials attributed the mass die-off to oxygen depletion caused by successive heatwaves since May. Water temperatures in the pond reached 24-25°C, a level fatal to species like trout that cannot tolerate temperatures above 20°C.