Migratory Movements of Pygmy Blue Whales (Balaenoptera musculus brevicauda) between Australia and Indonesia as Revealed by Satellite Telemetry

Abstract

In Australian waters during the austral summer, pygmy blue whales (Balaenoptera musculus brevicauda) occur predictably in two distinct feeding areas off western and southern Australia. As with other blue whale subspecies, outside the austral summer their distribution and movements are poorly understood. In order to describe the migratory movements of these whales, we present the satellite telemetry derived movements of eleven individuals tagged off western Australia over two years. Whales were tracked from between 8 and 308 days covering an average distance of 3,009±892 km (mean ± se; range: 832 km–14,101 km) at a rate of 21.94±0.74 km per day (0.09 km–455.80 km/day). Whales were tagged during March and April and ultimately migrated northwards post tag deployment with the exception of a single animal which remained in the vicinity of the Perth Canyon/Naturaliste Plateau for its eight day tracking period. The tagged whales travelled relatively near to the Australian coastline (100.0±1.7 km) until reaching a prominent peninsula in the north-west of the state of Western Australia (North West Cape) after which they travelled offshore (238.0±13.9 km). Whales reached the northern terminus of their migration and potential breeding grounds in Indonesian waters by June. One satellite tag relayed intermittent information to describe aspects of the southern migration from Indonesia with the animal departing around September to arrive in the subtropical frontal zone, south of western Australia in December. Throughout their migratory range, these whales are exposed to impacts associated with industry, fishing and vessel traffic. These movements therefore provide a valuable tool to industry when assessing potential interactions with pygmy blue whales and should be considered by conservation managers and regulators when mitigating impacts of development. This is particularly relevant for this species as it continues to recover from past exploitation.

Crowdsourcing Modern and Historical Data Identifies Sperm Whale (Physeter macrocephalus) Habitat Offshore of South-Western Australia

“…The Perth Canyon could be both a critical feeding area and nursery for matriarchal family groups. In the summer months, pygmy blue whales feed in the Perth canyon (Rennie et al, 2006(Rennie et al, , 2009Double et al, 2014) and other species of cetaceans are present year-round, including true blue whales (Balaenoptera musculus) over the winter and migrating humpback (Megaptera novaeangliae) and southern right whales (Eubalaena australis) (Mccauley et al, 2004).…”

Review of Underwater and In-Air Sounds Emitted by Australian and Antarctic Marine Mammals

“…Pygmy blue whales are considered subantarctic, not occurring as far south as Antarctic blue whales. They also migrate annually between higher latitudes in the summer and lower latitudes in the winter and are believed to roam as far north as the northern Indian Ocean and Banda Sea [77]. The Perth Canyon (WA; [78,79]) and the Bonney upwelling (SA; [80]) are two notable feeding aggregations of pygmy blue whales.…”

Description and seasonal detection of two potential whale calls recorded in the Indian Ocean

“…However, a low number of calls were detected in February-April in the south coast of Australia suggesting some Antarctic blue whale individuals may not migrate to feeding grounds (Tripovich et al, 2015). Australian pygmy blue whales are thought to migrate to Indonesia in the summer to breed and return to Australia in the winter to feed (Double et al, 2014). The Madagascan pygmy blue whales migrate south of Madagascan from late summer through winter to feeding grounds and return to higher latitudes in the end of autumn.…”