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Abstract:

To continue an annual series of aerial surveys since 1993 off the southern Australian coast between Cape Leeuwin WA and Ceduna SA, a survey was undertaken over five days from 18-23 August, 2018. A total of 1095 southern right whales were sighted, including 381 calves; these include double counts given that each flying leg is covered twice, ‘outward’ and ‘inward’. An additional 17 humpback whales (including three calves) were recorded during the survey. A comparison of the maximum counts for each survey leg with previous years, resulted in 2018 having a total of 789 whales and 279 cow/calf pairs which were both lower than in 2017 although still higher than any of the other previous years since 1993. The maximum counts for cow/calf pairs are used to obtain a population size estimate, which for 2018 is 3191 whales. This population estimate is for the ‘western’ Australian subpopulation which is considered to represent the majority of the ‘Australian’ population. The population trend analysis indicates a continued increase in whale numbers by approximately 6% per year (based on counts of cow/calf pairs), with no apparent slowdown in the population growth rate. From 6005 photographic images obtained, 329 have been selected for computer -assisted ‘matching’ with those (some 9000 images of over 2000 individuals) already available in the catalogue. All photo-identification and sightings data have been included and archived in existing databases.

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