Protecting large cetaceans from ship strikes in the Pelagos Sanctuary
Thea Jacob, Aimee Leslie, Denis Ody
International Whaling Commission
The Pelagos Sanctuary is severely impacted by maritime traffic with more than 18 million kilometres travelled in 2014 by vessels equipped with the AIS system. With an average growth rate stabilized at 4% per year (Piante & Ody, 2015), the traffic is expected to double every 17 to 18 years.
This traffic generates nuisances for cetaceans, disturbance and noise, but also the more serious risk of collisions that can lead to lethal injury. The collision rate is 3.25 times higher in the Pelagos Sanctuary than elsewhere in the Mediterranean (Panigada et al., 2006) because in this area there is a combination of high abundance of cetaceans and heavy marine traffic, especially ferries for French and Italian islands.
The theoretical collision risk calculation results in an annual number of potential collisions of 3465 (3168 for fin whales and 297 for sperm whales). The ecological cost (feeding, reproduction, socialization, etc.) of this disturbance is unknown but potentially significant.
If thousands of ships have travelled the Pelagos sanctuary in 2014, a relatively small number concentrate the collision risk. Thus a few hundred ships represent half of the traffic risk and generate a little less than half of the collision risk per day.
Concerning these 100 vessels, an annual budget of € 360,000 (3600 € per vessel) would make it possible to equip them with a REPCET type collision avoidance system, and potentially significantly reduce the collision risk.