Document ID: chunk:federal_register_of_legislation:F2015L01633:body:0:p14
Version: federal_register_of_legislation:F2015L01633
Segment Type: other
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Character Range: 37898–40895

used for filter feeding. Within Mysticeti, blue whales belong to the family Balaenopteridae (rorquals). Rorquals are characterised by throat pleats that allow the throat to expand when engulfing their prey.

There are four currently recognised subspecies of blue whales. Two are referred to as 'true' blue whales; the northern hemisphere subspecies, Balaenoptera musculus musculus, and the southern hemisphere subspecies, Balaenoptera musculus intermedia. The third subspecies is the 'pygmy' blue whale Balaenoptera musculus brevicauda known mainly from the southern Indian Ocean.  Balaenoptera musculus indica (Blyth 1859) or the Northern Indian Ocean blue whale subspecies was recently recognised. A Chilean subspecies has also been suggested15,25,94.

The two recognised Southern Hemisphere subspecies to which this Plan applies are the pygmy blue whale (B. m. brevicauda) and the Antarctic blue whale (B. m. intermedia), which are characterised by differences in morphology15,18,51,54,55,57,88, distribution15,18,51, vocal behaviour64,76 and genetics63.
Physical description
Blue whales are recognisable by a number of characteristics. They are the largest animal known to exist and are long-lived. The Antarctic subspecies can reach over 30m long and weigh up to 180 tonnes18. The longest recorded blue whale was a female from the Antarctic of 33.6m, and the longest pygmy blue whale was 24.4m51. They have mottled grey to almost black pigmentation which can be used to identify individuals from photographs (i.e. photo-identification)99. Compared to other cetaceans, they have a relatively small dorsal fin positioned far back on the body and this may remain underwater during surfacing. As with other baleen whales, females are generally larger than males. There is as yet no confirmed set of features that make the subspecies distinguishable at sea.

Reproduction
Blue whales reach sexual maturity at approximately 10 years old. They calve every two to three years, with gestation taking at least 10 months. Calves are 6-7m long at birth and 2.7 to 3.6 tonnes in weight, and are weaned at 7 months, by which time they are approximately 16m long117.
Foraging
Blue whales have the highest known prey requirements of any predator, consuming up to two tonnes of krill per day93. Blue whale feeding grounds are therefore required to be areas of high primary productivity that can support sufficient densities of krill, such as oceanographic upwelling or frontal systems.
Pygmy blue whales
Australia has two known seasonal feeding aggregations of pygmy blue whales supported by upwelling systems located at the Perth Canyon off Western Australia and the Bonney Upwelling system and adjacent waters off South Australia and Victoria44,45,92. Blue whales predominately occur in these regions from November to May44,45,71,7,92.
The Perth Canyon is a seasonally important area where pygmy blue whales feed on krill at depths of 200-300 metre in the canyon from January to May (with feeding peaking