The blue whales of the Savu and Banda Seas, Indonesia: Conservation planning for a highly migratory species

The Savu and Banda Seas are positioned in eastern Indonesia, at the nexus of two oceans, and are a central part of the Coral Triangle - the region with the world’s highest coral reef biodiversity. These waters inhabit at... [ view full abstract ]

The Savu and Banda Seas are positioned in eastern Indonesia, at the nexus of two oceans, and are a central part of the Coral Triangle - the region with the world’s highest coral reef biodiversity. These waters inhabit at least 23 species of marine mammals and include critical habitats for a population of ‘pygmy’ blue whales (Balaenoptera musculus brevicauda) that migrate from the Southern Ocean to Banda, via the migratory bottlenecks of the Savu Sea (Ombai-Wetar Straits) and Timor Leste.

In 2016 and 2017, two 10-day Rapid Ecological Assessments (REAs) for Marine Mammals were conducted in this remote region, with a combined survey effort of 2039 kilometers of track-line and 206.5 daytime survey hours. A total of 17 marine mammal species were positively identified during 95 group sightings, with a minimal animal count of 3019 individuals. Pygmy blue whales were relatively abundant with the second highest species-specific sighting frequency in both years. The surveys included ecological tracking of individual blue whales and obtained crucial insights on fine-scale habitat use. 

Survey outcomes have: a) confirmed the important ecological role of the Banda Sea as a migratory end-point or "destination" for endangered blue whales; b) expanded this critical habitat towards the Ceram Sea; c) identified important habitats for other oceanic cetaceans (i.e. West Ceram and Manipa Strait); d) provided an initial threat assessment including marine debris, fisheries interactions, oil and gas and shipping activities and e) contributed to the current development of Marine Protected Area (MPA) Networks in Indonesia and Timor Leste.