Monitoring of Marine Mammal Strandings Along French Coasts Reveals the Importance of Ship Strikes on Large Cetaceans

Although once considered rare, ship strikes are now recognized as the leading cause of human-induced mortality among large cetaceans along the French coast. An analysis of stranding data collected by the national network between 1972 and 2017 identified 51 fatal collision incidents out of 396 strandings of large cetaceans. Rorqual whales account for the vast majority of cases, with the fin whale (Balaenoptera physalus) being the most affected species (76.5% of identified collision cases). The situation is particularly critical in the Mediterranean Sea, where approximately one in five stranded cetaceans shows evidence of a collision, with the majority occurring in the Gulf of Lion and the Pelagos Sanctuary. The majority of fin whales killed in collisions had not reached sexual maturity (notably 15 out of 16 males), indicating that immature individuals are particularly vulnerable. The assessment of these collisions highlights the difficulty of achieving the “Good Environmental Status” (GES) required by the Marine Strategy Framework Directive (MSFD), underscoring the need for quantitative indicators and enhanced cross-border collaboration.