This is a technical report on the results from the 2021 aerial survey of southern right whales off southern Australia, specifically aimed at researchers and policy makers within the government. Collection of these data is a ‘high priority’ in the Australian EPBC Act Recovery Plan (Conservation Management Plan 2011-2021) to assess the current status of this threatened species and assess the effectiveness of federal and state management approaches that aim to facilitate this species’ recovery and range expansion. The whale count data from 2021 shows a significant decrease in overall sightings that has not been observed for over 13 years when compared to long term trend data for the population; last seen in 2007 (N = 286 individuals). The subsequent population estimate for the Australian ‘western’ subpopulation is 2,585 whales, which is also a significant decrease in estimated population size from 3,164 in 2019. The extremely low number of unaccompanied adults (N = 68) had the greatest impact on the overall number of sightings in 2020, and is the lowest number sighted since 1993 (N = 47). Previous surveys in 2007 and 2015 have been noted as years of low whale counts that had been deemed anomalous years, although the low numbers from this survey questions this and may suggest the 3-year female breeding cycle is becoming more unpredictable. Considerable inter-annual variation in whale numbers, and cycles in population growth, severely inhibits our ability to identify immediate threats to the population and strongly supports continued annual population surveys.

Annual aerial surveys of Australia’s ‘western’ population of southern right whales have been conducted between Cape Leeuwin, WA, and Ceduna, SA, since 1993 to monitor recovery from commercial whaling. The latest Hub-funded survey extended for seven days in August 2019. In 40 flying hours, 1111 right whales were sighted, including 425 calves, and 299 images were selected for computer-assisted ‘matching’ via the ARWPIC catalogue. The resulting population size estimate for ‘western’ Australian sub-population is 3164 whales. Estimates from 2018 and 2019 are the largest for the population since 1993 and are consistent with an increasing population trend of approximately 6% per year (based on counts of cow/calf pairs). Considerable annual variation in whale numbers, and cycles in population growth, makes it difficult to detect reliable annual changes in abundance and supports a continued sampling frequency of annual surveys.

Annual aerial surveys of Australia’s ‘western’ population of southern right whales have been conducted between Cape Leeuwin WA and Ceduna SA since 1993 to monitor recovery from commercial whaling. The latest Hub-funded survey extended for seven days in August 2019. Over 40 flying hours, 1111 right whales were sighted, including 425 calves, and 299 images were selected for computer-assisted ‘matching’ via the ARWPIC catalogue. The resulting population size estimate for ‘western’ Australian sub-population is 3164 whales. Estimates from 2018 and 2019 are the largest for the population since 1993 and are consistent with an increasing population trend of approximately 6% per year (based on counts of cow/calf pairs).