Outbreak of an unknown flagellate and a massive European conger eel mortality event in late summer 2024 in La Forêt Bay Brittany France)

An outbreak of an unknown flagellate, resembling certain raphidophycean fish-killers, caused seawater discoloration coinciding with a puzzling mass mortality of European conger eels in southern Brittany. The hypothesis suggests that the sedentary behaviour of conger eels, combined with anoxic conditions near the seafloor, explains their selective mortality.