Canyon effects structure fin whale feeding aggregations at Southern Ocean feeding grounds

Abstract Large fin whale feeding aggregations at Southern Ocean feeding grounds are one of the most striking predator–prey phenomena in the post‐whaling era, representing a visible sign of recovering large whale populations. Yet, the mechanisms shaping their occurrence have not yet been studied. We investigate spatial patterns of fin whale distribution along the Western Antarctic Peninsula, focusing on the occurrence of large aggregations. Using data from concurrent whale, krill, and oceanographic surveys conducted in 2023, we apply principal component analysis and fuzzy clustering to characterize aggregation hotspots on the feeding grounds. We identify hydrological signatures linked to shelf‐incising submarine canyons as the primary drivers of these hotspots. We suggest that enhanced water mass mixing promotes krill aggregation across age classes, providing concentrated prey fields that fin whales exploit. Tracking data further reveal that whales align their movements with canyon structures, underscoring canyon‐driven hydrodynamics as key habitat‐structuring features. These processes confine critical fin whale feeding habitat to a limited band along the shelf edge—an area that is also the main target of the commercial krill fishery. This spatial overlap raises concerns of competition and potential population‐level impacts, particularly as recovering fin whale populations increasingly depend on these limited foraging habitats, highlighting the need for targeted conservation measures around the Western Antarctic Peninsula.