This record provides an overview of the NESP Marine and Coastal Hub project "Mapping critical Australian sea lion habitat to assess ecological value and risks to population recovery". For specific data outputs from this project, please see child records associated with this metadata. -------------------- Populations of the endangered Australian sea lion have declined by >60% over the last 40 years. There is a marked uneven distribution in abundance and trends across the species range, suggesting that localised risk profiles from threats vary at small spatial scales. Fine scale differences in habitat use are thought to underpin these differences, yet knowledge about the species dependency on key habitats and their vulnerability to human impacts is limited. This project deployed underwater cameras onto sea lions to identify and map their critical habitats, assess their ecological value and identify risks to populations. Tagging took place at three sea lion colonies adjacent to Commonwealth and state marine reserves off South Australia including Olive and Pearson Islands (Western Eyre Marine Park) and Seal Bay (Southern Kangaroo Island Marine Park). Results from this study improve our understanding of threats to sea lion populations and support future conservation actions to recover the species. Outputs • Tracking data from sea lion-deployed tags: location, depth, time, temperature, light, acceleration [dataset] • Timestamped video footage from sea lion-deployed cameras [dataset] • Final project report [written]

The Maugean Skate Zearaja maugeana is a micro-endemic species known from only two isolated estuaries, Bathurst and Macquarie Harbours in southwestern/western Tasmania. This constitutes one of the most limited distributions of any known extant elasmobranch. As a result, the species is listed as ‘Endangered’ under the Threatened Species Protection Act (Tasmania) and the Environmental Protection and Biodiversity Conservation Act (Commonwealth). Even though it was first discovered in Bathurst Harbour, most of what is known about the species comes from the Macquarie Harbour population. Only four individuals have ever been reported in Bathurst Harbour, with the last known sighting occurring in 1992. This study used environmental DNA (eDNA) to determine the presence/absence of the Maugean skate in Bathurst Harbour on the southwest coast of Tasmania. Water samples were collected from the seafloor in Bathurst Harbour in November 2021 and February 2022, and in Macquarie Harbour (control samples) in December 2021. Samples were filtered using a self-preserving eDNA sampling system. Following each survey DNA from the samples was extracted and analysed through qPCR amplification. Mitochondrial primer pairs from two gene regions were used to detect the presence of Maugean skate DNA in the samples. Where possible, positive detections were sequenced, and their identity verified.