Document ID: chunk:federal_register_of_legislation:F2024L00930:reg:2:p6
Version: federal_register_of_legislation:F2024L00930
Segment Type: reg
Provision Reference: reg 2 (pt 6/48)
Character Range: 78536–81414

in southern right whales is thought to be approximately 11 - 12 months (Burnell 2001), lactation lasts at least 7 – 8 months (Tormosov et al. 1998), with weaning occurring within 12 months (Lockyer 1984). The apparent age at first parturition is reported to occur at a minimum of five years and average of nine years in whales utilising the Head of the Bight (Charlton et al. 2022). Southern right whales from the Australian population are known to still be reproductively viable to at least 41 years of age and the oldest recorded whale in Australia is estimated to be at least 50 years old (Charlton et al. 2022). Surface active mating and socialising groups observed in reproductive areas are believed to be involved in mating (Burnell et al. 1990, Parks et al. 2007, Charlton 2017), with adults not accompanied by a calf making up approximately 20 percent of overall sightings at major calving grounds (Charlton et al. 2019).
  Figure 1 Physical morphology of a southern right whale mother and calf.
  © Joshua Smith.

    Figure 2 Southern right whale callosity features used for photo-identification.
    © Fredrik Christiansen, Aarhus University.
However, mating and conception does not exclusively occur in reproductive areas of the Australian coast, yet there is limited understanding on the extent it occurs outside known reproductive areas. Known females are rarely observed on the Australian coastline in the year prior to calving, suggesting conception may predominantly occur away from calving grounds, potentially on the feeding grounds (Watson et al. 2021). It is difficult to determine the sex of whales at sea which provides challenges to identifying mating behaviour. Whales in close association with a calf over extended periods (weeks) are typically identified as females, and sex can be determined by photographing the ventral ano-genital configuration. Mating behaviour typically involves a single female being pursued by several males over several hours to several days and males may jostle for position and attempt to mate from an inverted position underneath the female (Donnelly 1967, Burnell et al. 1990).
Southern right whales are capital breeders, and the female reproductive cycle is closely linked to their migratory cycle. They build up energy stores on high latitude feeding grounds, which are then relied upon while on their breeding/calving grounds to enable lactation during a time that they do not feed (Lockyer 2007). Given finite energy stores on the calving grounds, and the energetic costs of reproduction to females, environmental influences and/or disturbance from anthropogenic activities may impose further demands on the whale's limited energy stores and affect the body condition of lactating females and the reproductive viability of offspring. There is a significant energetic cost to the mother in the late stages of gestation