Human economy is based on exchanges between countries and therefore on maritime traffic. Nearly 100 000 commercial ships constantly cross the oceans.
Because of its scale, this activity is the source of numerous disturbances for marine mammals, such as noise pollution and chemical pollution. Since the 1990s, another threat has been identified: collisions.
Collisions between ships and large cetaceans occur wherever there is dense traffic and high concentrations of animals. Today, they represent a threat to several whale populations around the world, and in particular to the North Atlantic Right Whale, which was reclassified as Critically Endangered in 2020, and of which there are only about 400 individuals remaining.
The causes of these accidents are not well known, but it seems that young adults, who are less experienced, are more often victims of collisions. Furthermore, the noise emitted by ships propagates backwards, making detection more difficult. A study using tags set up on Blue Whales in California showed that individuals reacted at the last moment to the approach of a ship.
Several actions can be considered to reduce the risk of collision, but none is completely satisfactory. Moving shipping lanes out of the areas most frequented by whales seems to be the best option.
Reducing vessel speed is also effective as it is a key factor of collision: a faster vessel leaves less time for the animal to avoid it. Moreover, if the collision cannot be avoided, high speed reduces the chances of survival.
Anti-collision and whale tracking system
Maritime traffic is a vital activity for the economy of the French West Indies. There is significant traffic between the different islands, so the risk of collisions is real within the Agoa Sanctuary.
The decree of August 8, 2016 obliges all vessels over 24 metres flying the French flag and sailing more than 10 times per year in the Agoa and Pelagos Sanctuaries to be equipped with a device for sharing whale positions in order to avoid collisions.
The software REPCET, for REPérage des CETacés (locating cetaceans), was developed for this purpose in the French Mediterranean and could be used in the Caribbean.