PhD Candidate

Foraging, migration, and communication in eastern Indian Ocean pygmy blue whales Balaenoptera musculus brevicauda

Supervisors: Robert McCauley, Christine Erbe, Michele Thums, Curt Jenner, Micheline Jenner

Blue whale Balaenoptera musculus populations are structured throughout every ocean basin forming numerous sub-populations across 4 confirmed subspecies. In the eastern Indian Ocean, a discrete population of the pygmy subspecies B. m. brevicauda exists, migrating between their tropical terminus in southern Southeast Asia and temperate waters south of Australia. It is not yet clear if this migration is a result of their reproductive habits or foraging ecology. Rather than the feast and famine life history, these pygmy blue whales forage year-round upon ephemeral and seasonal food resources in the form of various planktonic Euphausiid krill species. Understanding the environmental drivers behind their selection of foraging locations is key to investigating the motivations of their migratory behaviour. Pygmy blue whales communicate with conspecifics using a variety of vocalisations that can be monitored passively to identify their presence, and potentially be deciphered to reveal behaviour. This research aims to understand the driving factors behind migration, foraging, and communication in the eastern Indian Ocean pygmy blue whale, which will enable the identification of areas important to the ecology of this population.

Pre-existing biotelemetry tag datasets will be employed to explore movement and foraging behaviours across multiple data resolutions. To improve our understanding of pygmy blue whale foraging ecology in this region, we will attempt to explain the derived behaviours with environmental processes in two locations: Perth Canyon and Ningaloo. The context of eastern Indian Ocean pygmy blue whale vocalisations will be investigated by deploying tags capable of acoustic logging and orientation estimation at an individual level, ideally identifying acoustic signals of foraging behaviours. Finally, habitat suitability modelling for pygmy blue whale vocalisations on the Northwest Shelf of Australia will be conducted to identify areas of importance of this population in this region, accounting for knowledge accumulated during this project. This research is crucial for the effective management of this pygmy blue whale population and will improve our ability to understand how the population will react to a changing climate.