Document ID: chunk:federal_register_of_legislation:F2015L01633:body:0:p20
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Report to AMMC).
Finally, acoustic recordings identify calls in the Perth Canyon as being the same call types as in Geographe Bay, further suggesting that they are from the same population. However, this has not yet been genetically confirmed as the number of available samples for genetic analysis from this area is still small4. The genetic makeup of blue whales which use the East Coast of Australia is not known.
Antarctic Blue Whales
Genetic evidence has shown that Antarctic blue whales may consist of more than one genetic population, which is possibly driven by female site fidelity to particular regions of Antarctica105. However this requires further clarification.

Abundance and population trends
Abundance and population trends of blue whale populations using Australian waters are described below in the context of current population structure knowledge.
Pygmy blue whale
Blue whales from the two known Australian feeding aggregations belong to the same population5, and therefore population abundance should be estimated together for these feeding aggregations. Abundance estimates based on photo-identification mark-recapture from 1999/2000 to 2004/2005 season for blue whales in the Perth Canyon are between 532 and 1,75452 individuals, which generally agree with acoustic abundance estimates of 662 to 1,559 calling blue whales migrating south in 2004 past Exmouth in Western Australia72 and a 1992/1993 season cruise which estimated 671 (95% interval 289-1,557) individuals offshore of southern Western Australia (35-45⁰ South, 115-125⁰ East)56.
However, it is unknown what proportion of the total population these estimates encompass. This is a complex issue as there is the potential for between-year differences in habitat use due to, for example, differences in primary productivity between years which may bias estimates that are based on only one season of data. The degree of connectivity between different habitats is also poorly understood. While there is no evidence of genetic differentiation between the Bonney Upwelling and the Perth Canyon 5, there is the possibility of site fidelity of individuals to different feeding grounds. It is also unknown to what extent blue whales using the Australian feeding aggregations also use feeding habitat outside these areas, such as the Sub-tropical Convergence.
There is little knowledge of the pre-exploitation abundance of Australian pygmy blue whales, making it difficult to assess population recovery. Pygmy blue whales in the sub-Antarctic are estimated to have reduced from 7,598 at the start of the 1960/1961 season to 3,996 at the end of the 1971/1972 season118, however this is based on out-of-date methodology and the population identity of these sub-Antarctic blue whales is unknown.
Preliminary estimates of the number of pygmy blues caught are 13,02216, though this encompasses all catches from South Africa to New Zealand and the northern Indian Ocean for which the extent of connectivity is