Occurrence of leatherback turtles around Australia

Abstract

ABSTRACT: Leatherback turtles Dermochelys coriacea are a pelagic species, globally endangered due to multiple anthropogenic impacts. Although protected under Australian legislation, species-specific practical protection has been hampered by sparse information about leatherback distribution in Australian waters. To fill this gap, we obtained records of leatherback interactions with fisheries gear, opportunistic sightings at sea, beach stranding events and non-target capture in shark control programs. We evaluated the temporal and geographic distribution of records and assessed potential bias in observation opportunity based on human population density and fishery activity. Based on 1073 leatherback observations from 1990 to 2022, we found that sightings were unevenly distributed right around Australia, encompassing longitudes from 105.4°E to 165.1°E and latitudes from 43.7°S to 10°S. In the extreme southeast of Australia, hotspots were apparent during December to March (austral summer). In temperate and subtropical latitudes to the west and east of Australia, hotspots appeared predominantly during June, July and August (austral winter), but were also apparent, albeit weaker, to the east in all other months. Our results confirm that the species is present around Australia in all months of the year and has a much wider geographic and offshore distribution around Australia than previously reported. Hence, we inferred that Australian waters are highly important for migrating and foraging leatherbacks from subpopulations breeding in the Pacific and Indian Oceans, all of which are at high risk of extinction, and we suggest that Australian management agencies have crucial roles in protecting these endangered animals.