More and more anthropogenic causes
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
By-catch
Incidental catches by fishing gear are the main causes of marine mammal mortality.
Less ressources
Overfishing is starving sea birds. Fishing discards are a less energetic food.
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.
