Pairing AIS data and underwater topography to assess maritime traffic pressures on cetaceans: Case study in the Guadeloupean waters of the Agoa sanctuary
Bénédicte Madon, Damien Le Guyader, Jean-Luc Jung, Benjamin De Montgolfier, Pascal Jean Lopez, Eric Foulquier, Laurent Bouveret, Iwan Le Berre
Maritime transportation forecasts project an increase in shipping. In this context, interactions with cetaceans are of growing concern especially when relevant biological data are not available to monitor the impacts. The Agoa sanctuary in the Wider Caribbean region faces this situation. To overcome this issue, we used AIS data to estimate three pressure types from maritime traffic associated with known impacts for cetaceans: (1) “intensity” corresponding to the frequency of vessel presence, (2) “occupancy” corresponding to the duration of ship presence, known to lead to disturbance and noise-related impacts and (3) “speed” presenting the risk of physical injuries from collisions. A simplified approach of the Cumulative Effect Assessment framework was used. We mapped species underwater topographic preferences as a proxy for their distribution to link habitat features with traffic pressure maps to evaluate pressure levels and types. Results showed that three species were more at risk from intensity and speed in the plains: the bottlenose dolphins, the Fraser’s dolphins and the short-finned pilot whales. The speed pressure had the highest score over the habitat types slopes, canyons and valleys, placing sperm whales, Cuvier, Blainville’s and Gervais’s beaked whales at higher risk of collision in these areas. Humpback whales and pantropical spotted dolphins faced a higher risk of disturbance over the continental shelf along the West coast. We recommend a precautionary approach in the Agoa sanctuary: speed reduction in the Pointe-à-Pitre-Marie-Galante route and displacement of shipping lanes to move maritime traffic away from the West Coast.
Marine Policy Vol. 143, 2022, 105160