Document ID: chunk:federal_register_of_legislation:F2024L00930:reg:2:p11
Version: federal_register_of_legislation:F2024L00930
Segment Type: reg
Provision Reference: reg 2 (pt 11/48)
Character Range: 91842–94656

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 have implications on population size estimation in future years if the change applies across the population.
The most recent population size estimate for the western population derived from the annual aerial survey is 2,549 whales (1993 – 2021), with a per annum rate of increase of ~4.3 percent (C.I. 2.8 – 5.8) for all animals observed and ~5.4 percent (C.I. 3.6 - 7.2 percent) for mother and calf pairs observed (Smith et al. 2022). However, low whale counts in a given year can influence subsequent population estimates and the 2017 estimates of ~3,200 whales and rate of increase p.a. of 5.5 percent (C.I. 4.0 - 7.3 percent) for all animals and 6.2 percent (C.I. 3.9 - 8.6 percent) for mother-calf pairs are likely a better representation of the status (Smith et al. 2019). The western population is therefore recovering near to the maximum rate of population growth biologically possible. The whales that utilise the Head of Bight potentially represent 21 percent of the western population, with an estimated mean rate of increase of 3.2 percent (± 1.3 percent) per annum and 4.6 percent (± 1.7 percent) per annum for females with a calf (Charlton et al. 2022). Although recently (from 2007), the long-term population abundance data have shown greater inter-annual variation and anomalous years of pronounced low whale numbers are potentially becoming more frequent (Evans et al. 2021, Charlton et al. 2022, Smith et al. 2022).
Based on breeding females sighted across the period 1996 to 2017 prior to the post-breeding southward migration (i.e. month of September), an estimate of population size for the eastern population resulted in 268 (146-650) whales (1996 - 2017) and a rate of increase of 4.7 percent (C.I. 2.3 – 7.3 percent) (Stamation et al. 2020). Contrary to the increase estimated for the population, there is no evidence of an increase in annual numbers of mother-calf pairs at Logan's Beach, the only established calving aggregation in the south-east of Australia (Stamation et al. 2020). Based on these estimates, the eastern population appears to be recovering at a slower rate than the western population, and abundance remains very low in comparison with expectations based on historical evidence of occupation (Pirzl 2008, Stamation et al. 2020).

2.8         Distribution and habitat occupancy
Southern right whales have a circumpolar distribution in the Southern Hemisphere approximately between latitudes 20°S and 65°S (Kenney 2018). Reproductive areas where females calve and nurse their young appear to be exclusively coastal, occurring either off