Document ID: chunk:federal_register_of_legislation:F2024L00930:reg:2:p10
Version: federal_register_of_legislation:F2024L00930
Segment Type: reg
Provision Reference: reg 2 (pt 10/48)
Character Range: 89016–92076

mitochondrial DNA (mtDNA; female inherited) haplotype frequencies (Carroll et al. 2011). This was supported by further analyses of mtDNA using an increased sample size that identified genetic differentiation between the Australian western and eastern populations and individuals from New Zealand calving grounds. These findings are consistent with long-term fidelity to calving areas (Carroll et al. 2015). In contrast though, no genetic differentiation has been observed between the western and eastern population management units using microsatellite DNA, and between individuals sampled from the Australian calving grounds and migratory corridors based on either mtDNA haplotype or microsatellite allele frequencies (Carroll et al. 2015). This indicates whales from the calving areas across Australia are mixing on shared migratory corridors.

2.7         Abundance and population trends
The western and eastern populations of southern right whales in Australia demonstrate varying patterns of recovery, following severe depletion from commercial whaling. The western population has been monitored annually at varying extents of its range since 1976, which represents the longest continuous record of southern right whale abundance in Australia and is central to understanding recovery of the species post-exploitation. Annual aerial surveys were initially conducted in WA between Cape Leeuwin and Israelite Bay, which were extended further east to Twilight Cove from 1985, and then further east again to Ceduna in SA in 1993 (Bannister 1990, Bannister 2001, Evans et al. 2021, Smith et al. 2022). Land-based clifftop surveys have been conducted at the Head of Bight reproductive aggregation site since 1991, providing information on the relative proportion (~0.21) of the western population and associated growth trends and demographic data (Burnell 2001, Charlton et al. 2022). Monitoring in the south-eastern parts of Australia have largely been opportunistic in nature, with the exception of an aerial survey conducted twice between Ceduna and Sydney (including Tasmania) in 2013 and 2014 (Watson et al. 2015). Long-term monitoring of Australian southern right whales has thus focussed on the largest remnant part of the population, which have estimated inter-annual trends in relative abundance and rates of population increase and studied elements of reproductive biology and behaviour.
The maximum biological rate of increase for southern right whales across their range is estimated at approximately 6 - 7 percent per year (IWC 2013). The formation of breeding cohorts (section 2.4.2) due to a three year calving cycle results in inter-annual variation in population counts of southern right whales observed in Australian waters and consequently the estimation of overall abundance and trends need to be calculated over multi-year periods (i.e., a 3-year rolling average). At the Head of Bight, the mean calving interval for breeding females during 2015 - 2021 has been observed to increase from three to four years (Charlton et al. 2022), which may