Understanding pygmy blue whale movement and distribution off north Western Australia

Abstract

The blue whale (Balaenoptera musculus) is a listed endangered species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. A distinct population of blue whales, the eastern Indian Ocean pygmy blue (EIOPB) whale, migrates along the Western Australian coast to the Banda Sea in Indonesia. Their distribution and the delineation of biologically important areas (BIAs) in the north west marine region of the Australian coast are based on limited data with two possible foraging areas identified in the Blue Whale Conservation Management Plan – off Ningaloo and Scott Reef. This uncertainty is a problem because effective management of the many anthropogenic activities associated with industrial development in this area (e.g. oil and gas, commercial shipping and fishing) relies on robust data. To this end, we combined new satellite tag deployments on EIOPB whales off Ningaloo Reef with existing satellite tracking data to provide sufficient data to understand the spatial and temporal extent of the population’s distribution and the movement behaviour in the north west. We also deployed passive acoustic instruments at North West Cape and combined these with existing passive acoustic data from the north west, including 18 deployed instruments and 14 ocean bottom seismometers (OBSs). To fill data gaps in our understanding of EIOPB whale broad scale distribution on their northern and southern migration, we undertook three passive acoustic surveys using ocean gliders, thereby providing extensive spatial coverage across the north west.