Habitat critical to the survival of humpHabitat critical to the survival of humpback whales

Habitat critical to the survival of humpback whales

It is not currently possible to define habitat critical to the survival of humpback whales. The flexibility and adaptability of the species’ habitat requirements are not known, and it is not clear if all the currently used areas are critical to survival or whether the loss of one of these areas could be sustained. The plan therefore focuses on habitat important to the survival of humpback whales.

For the purpose of this plan, habitat important (and potentially critical) to the survival of humpback whales is defined as those areas known to seasonally support significant aggregations of whales, and those ecosystem processes on which humpback whales rely - in particular known calving, resting and feeding areas, and certain sections of the migratory pathways.

Figure 1 illustrates the distribution, indicative migratory pathways and recognised aggregation areas for humpback whales utilising Australian waters. It should be noted that the boundaries presented on the map are indicative only and there is inherent variability in the movements of the species.

Calving

Currently known calving areas (based on observations of mothers with very young calves) for Australian humpback whales include:

• Western Australia - Southern Kimberley between Broome and the northern end of Camden Sound;
• Queensland - Great Barrier Reef complex between approximately 14°S and 27°S; and
• less frequently along the migratory pathways.

Migration

Along parts of the migratory route there are narrow corridors and bottlenecks resulting from physical and other barriers where the majority of the population passes close to shore (i.e. within 30 km of the coastline). These habitat areas are important during the time of migration and include:

• Western Australia - Geraldton/Abrolhos Islands, and Point Cloats to North West Cape; and
• Queensland - east of Stradbroke Island, and east of Moreton Island.

Resting

Resting areas are used by cow-calf pairs and attendant males during the southern migration. These whales appear to use sheltered bays to opportunistically rest during migration to the feeding grounds and include:

• Western Australia - Exmouth Gulf, Shark Bay, and Geographe Bay;
• Queensland – the Whitsundays, Hervey Bay, Moreton Bay, the Swain Reefs complex Great Barrier Reef, Bell Cay, and the Palm Island Group; and
• New South Wales - Twofold Bay and Cape Byron.

Feeding

Feeding occurs primarily on Antarctic krill which congregates around the Antarctic continental shelf break and productive, transitional ice-edge zone. Oceanographic features that concentrate krill are likely to attract predators such as humpback whales. Humpback whales from the Australian west and east coast populations are known to mix to some extent at these feeding grounds.