A global study published in PNAS and co-authored by MegaMove Lead Coordinator Assoc Prof Ana M. M. Sequeira and multiple MegaMove members, has revealed extensive overlap between whale shark movements and global marine traffic — identifying key collision-risk hotspots across all major ocean basins.
The research, led by Freya Womersley and the Global Shark Movement Project, analysed satellite tracks from 348 individual whale sharks and overlaid them with Automatic Identification System (AIS) data from large vessels. The findings show that over 90% of whale shark horizontal space use overlaps with large vessel routes, with nearly 30% of their core aggregation zones sitting within the highest collision-risk areas.
Collision events between large vessels and whale sharks are rarely observed or reported due to the whale shark tendency to sink when deceased. However, the study found evidence that such events may be a significant source of undetected mortality for this species, showcasing situations where tracked individuals exhibited dive profiles consistent with fatal ship strikes in areas of high shipping traffic.
The work calls for urgent mitigation measures in high-risk areas, such as reducing vessel speed and improving global reporting. These insights demonstrate how biologging and movement ecology can help identify spatial priorities to reduce human impact on vulnerable marine megafauna.
