Eastern Indian Ocean Blue Whale Migratory Route IMMA

Criterion A – Species or Population Vulnerability

The total eastern Indian Ocean blue whale population was estimated at 662-1559 in 2010 (McCauley and Jenner, 2010). Blue whales are Red Listed by the IUCN as Endangered (EN) though the pygmy blue whale (Balaenoptera musculus brevicauda subspecies) has not yet been evaluated.

Criterion C: Key Life Cycle Activities

Sub-criterion C2: Feeding Areas

The application of time in area spatial analysis of satellite tracking data from pygmy blue whales from the Perth Canyon (Double et al., 2014) show areas of high occupancy along and within the migratory path. Lunge feeding behaviour was recorded by a lander tag which recorded dive data as well as location data (Owen et al., 2016). Double et al. (2014) identify Perth Canyon/Naturalist Plateau and also Ningaloo Reef as the main regions of high occupancy. Areas where animals have high occupancy are usually considered important and are often indicative of foraging behaviour (Kareiva and Odell, 1987) but also resting and breeding (Bailey et al., 2009). It was suggested that the high occupancy reported at Ningaloo Reef may be attributed to the fact that the whales were following the shelf as it narrows around the North-West Cape area (Double et al., 2014), however the fact that milling was also reported (Double et al., 2014) and that lunge feeding behaviour is commonly observed in this area (Michele Thums, Curt Jenner, Tiffany Klein pers comm), suggests that Ningaloo is in fact a feeding area. The Australian Government’s Conservation Management Plan for Blue Whales identifies the Perth Canyon/Naturaliste Plateau as “known foraging” and the area off Exmouth (Ningaloo) and Scott Reef as “Possible Foraging” areas which are protected under the Environment Protection and Biodiversity Conservation (EPBC) Act 1999, (Commonwealth of Australia, 2015). All these areas are considered “known foraging” in the Australian Government’s CVA (Figure 1), although not defined under the EPBC Act. Although there are anecdotal reports of pygmy blue whales feeding at Scott Reef, no published evidence could be found. But note that the IMMA encompasses all the known and possible foraging areas identified by the Australian Government and CVA and others that might be used by pygmy blue whales along their migration. The identified foraging areas can be considered important to the survival of blue whales as they seasonally support highly productive ecosystem processes on which significant aggregations of whales rely (Commonwealth of Australia, 2015). Antarctic blue whale calls have also been recorded in the Perth Canyon (Balcazar et al., 2015) but use of the Canyon by the species is not well documented.

Sub-criterion C3: Migration Routes

Satellite tracking data from pygmy blue whales consisting of 11 tagged in the Perth Canyon, Western Australia (Double et al., 2014), 13 tagged in the Bonney Upwelling, South Australia (Moller et al., 2015), one of which migrated along the WA coast, 1 tagged 35 km north of the Perth Canyon (Owen et al., 2016) and 1 tagged at NW Cape (AMS, 2009) have identified the area from the southern tip of Australia up to the Banda and Molucca Seas as the migratory pathway of pygmy blue whales.