The causes of mortality of stranded animals are multiple. A distinction is made between those of natural and man-made origin.
Natural causes
Natural mortality
The stranded dolphins were old, very young or pregnant females.
Viral pathologies
Death is caused by a virus, bacteria or parasites.
Predation
The animal was attacked by a predator.
Inter or intra specific competition
The animals fought and their fight resulted in death.
Anthropogenic (man-made) causes
Ship strikes
The intensification of maritime traffic is causing deadly collisions with large marine mammals.
Pollutions
Oil spills, micro-plastics, chronic chemicals, noise pollution, the degraded marine environment affects their survival.
Global changes
Global warming is changing ocean productivity and species ranges. Marine food chains are changing, affecting marine mammals..
Variations in oceanographic conditions
El Nino, for example, in the Pacific, is a climatic phenomenon produced by oceanic and atmospheric deregulation, resulting in a rise in water surface temperature.
