Preliminary results of 2017 IWC comparisons among Southern Hemisphere blue whale catalogues off Australia, New Zealand and Sri Lanka regions

Blue whales are known to occur off Australia, New Zealand and Sri Lanka but little is known about their long-term movements. The Southern Hemisphere Blue Whale Catalogue is a platform to share individual photo-identification catalogues among blue whale researcher groups. Comparisons of 698 photo-identified blue whales from seven different research groups working in the Perth Canyon (west Australia), Geographe Bay (west Australia), Bonney Upwelling (southern Australia), around New Zealand, and Sri Lanka provided sixteen whales resighted between different areas. Matches have been found within Australian catalogues and within New Zealand catalogues but no matches have been found between regions. Blue whales initially sighted in the Perth Canyon, Geographe Bay and the Bonney Upwelling were subsequently resighted in any of these areas, representing a high level of connectivity between these areas and thus, strengthening the hypothesis of one distinct population of Australian whales. These results also support the hypothesis of an isolated New Zealand blue whale population from the Australian population. Further efforts are needed to compare photo-identification catalogues from these areas with other catalogues from the eastern South Pacific and Southern Ocean to better understand population structure.