La Rochelle, France (7 jours/7)

Causes of strandings

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.



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


Incidental catches by fishing gear are the main causes of marine mammal mortality.


Less resources

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.



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.