Cetaceans exhibit region-specific habitat preferences across tropical waters

To implement effective and appropriate conservation measures, especially in less studied tropical areas, a better understanding of cetacean distribution and habitat preferences is needed. Our aim was to predict the distribution of cetaceans in five tropical marine subregions and to compare their habitat preferences in subregions located in three different oceans. Using data collected during the large-scale REMMOA aerial surveys, we created species distribution models based on sighting data and environmental variables integrated over the water column and transformed using principal component analysis for eight cetacean species groups. We summarised the distribution maps using hierarchical clustering on principal components to highlight distribution patterns common to species groups in the different subregions. Overall, no species group exhibited similar relationships with environmental conditions across all subregions, though certain species groups did show comparable relationships with specific variables in certain subregions. This suggests that cetaceans exhibit region-specific habitat preferences across tropical waters, with certain distribution drivers operating similarly for some populations in some subregions. In particular, most species groups favoured oceanographic structures such as continental slopes, while others, mainly continental shelves, were only preferred by a few species groups. Finally, we found that the distribution patterns of species groups were congruent within oceanographic subregions. These results will inform marine spatial planning for conservation and maritime development purposes, and can also be used to relocate maritime activities to areas where they will have a lesser impact, i.e. away from areas with high cetacean densities that support vital activities such as feeding and reproduction.