Document ID: chunk:federal_register_of_legislation:F2013L00289:body:0:p19
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survivorship, but this has not been measured.

Mortality rates for adult southern right whales from the southwest Australian population are assumed to be low and survivorship high, given their recent consistent rate of population increase of approximately 6.8 per cent each year. Mortality and survivorship rates differ for the south-east Australian population, where recovery has been poor35. Poor recovery in the south-east may be a result of the more severe historical local extirpation there84, rather than low survivorship.

Population structure
Southern right whales are the sole representative of the family Balaenidae in the southern hemisphere. They are closely related to northern hemisphere right whales E. glacialis (North Atlantic) and E. japonica (North Pacific)90, and although very similar, the species of the two hemispheres are reproductively isolated from one another by the geographic separation of calving grounds and asynchronous breeding seasons95.

Australian southern right whale populations have different mtDNA haplotype frequencies from other southern hemisphere populations although nuclear DNA structuring is very low8, 35, 77. This genetic pattern is consistent with mating in offshore feeding areas, coupled with females showing strong fidelity to calving grounds, although small numbers of females calve in both Australian and New Zealand waters.

Southern right whales in Australian waters were until recently considered to be one population. It is now proposed, based on differentiation in mtDNA haplotype but not nuclear gene frequencies, that south-east Australian right whales may be demographically separate from those in south-west Australia, although they may interact for the purposes of mating35. This means conservation management needs to be based around the existence of two populations in Australian waters with different recovery rates, rather than the single population model that was assumed previously.

Abundance and population trends
The population of Australian southern right whales has been monitored annually since 1976. Abundance estimates and trends for Australian southern right whales are available from the south-west Australian population for the area between Cape Leeuwin, WA and Ceduna, SA 10, 11, 12, 13. The minimum size of that population is estimated at 2900 with a 6.79 per cent increase each year (95 per cent confidence intervals 3.88–9.78)11. The south-west population is therefore recovering at, or near, the maximum rate of population growth biologically possible.

No reliable abundance estimate or trend is available for the south-east Australian population but the total Australian population – that is, the south-west and the south-east populations – is estimated to be in the vicinity of 3500 individuals11. There are some signs of slow recovery in the south-east Australian population, with sightings apparently increasing gradually over the last 10 years in a few locations in NSW, Victoria and Tasmania35. However, sighting records for the Warrnambool region -a principle calving area- show no