Previously foraging in pygmy blue whales was inferred from horizontal movement behaviour from satellite tracking data. Here nine individuals were tagged with GPS and pop-up archival tags providing depth and accelerometry to determine where actual foraging occurs. The depth time series allowed us to distinguish foraging dives, with accelerometry data key to distinguishing lunge-feeding.
Foraging predominantly occurred in three offshore areas: 1) Perth Canyon, 2) west of the Abrolhos Islands, and 3) Ningaloo region. Compared to the Perth Canyon and Abrolhos Islands, foraging dives at Ningaloo were shallower, horizontal travel rates were faster, and there was an absence of a diurnal pattern in diving. This suggests that pygmy blue whales at Ningaloo may forage opportunistically on more ephemeral prey. Foraging dives were also detected in the Savu Sea, offshore of Bremer Bay, and far off the continental shelf in northern Western Australia.
Areas where foraging dives occurred had a broad spatial overlap with areas of inferred foraging, despite a weak temporal relationship. However, the size of the foraging areas based on kernel utilisation distribution were much smaller when derived from the actual foraging dives. This improves the spatial delineation of pygmy blue whale foraging areas; key information needed for management.