Document ID: chunk:federal_register_of_legislation:F2024L00930:reg:2:p9
Version: federal_register_of_legislation:F2024L00930
Segment Type: reg
Provision Reference: reg 2 (pt 9/48)
Character Range: 86391–89311

the end of the sound. The upcall is considered the primary contact call used by both males and females of all age classes of right whale that may relate to the individual identity of a whale (Clark 1982, McCordic et al. 2016), and constituted ~76 percent of all vocalisations in the Australian WA and SA aggregation areas (Ward 2020). Consequently, given it is the most dominant vocalisation type it is predominantly used in passive acoustic monitoring to detect the presence of right whales (Van Parijs et al. 2009, Parks et al. 2011).
Lactating females with calves on calving grounds in both the North Atlantic and Australia have been found observed to produce vocalisations at low amplitude (123 ±8 dB and 133 ±10 dB re 1 µPa rms for non-harmonic and harmonic sounds, respectively; Flinders Bay, Western Australia), and relatively infrequently, potentially as a strategy to decrease the risk of acoustically alerting predators of their presence (Nielsen et al. 2019, Parks et al. 2019, Zeh et al. 2022). North Atlantic right whales have been reported to increase the amplitude of their upcall in response to increasing background noise levels (Parks et al. 2010), and there is also evidence that ship noise can increase stress in right whales (Rolland et al. 2012). To date, similar studies on the responses of southern right whales to increasing background noise or to noise produced by ships has not been undertaken in Australia, although similar behavioural responses by southern right whales would be plausible.

2.6         Population structure
Southern right whales that occur seasonally off the Australian coast are identified as derived from two populations: the western and eastern populations. This delineation of populations is based on genetic differentiation (Carroll et al. 2011, Carroll et al. 2015) and varying rates of population increase (Stamation et al. 2020, Watson et al. 2021, Smith et al. 2022), resulting in differing recovery trajectories likely as a result of differences in historical whaling pressure as discussed in section 2.3. The western population occurs off Western Australia and South Australia waters, while the eastern population occurs off coastal waters of Victoria, Tasmania, New South Wales, and Queensland. The two populations are proposed as two distinct management units (Brownell et al. 1986, Carroll et al. 2015), whereby recruitment from within the management unit is more important to its maintenance than immigration from neighbouring populations (Carroll et al. 2015).
Delineation of distinct western and eastern Australian populations was initially made on the basis of 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