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 will deploy underwater cameras onto sea lions to identify and map their critical habitats, assess their ecological value and identify risks to populations. Results will 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]

Quantitative surveys were undertaken at five sites in the Kent Group, north eastern Tasmania (Murray Pass, Winter Cove, Little Squally Cove,and southern end of Erith Island) by divers using underwater visual census methods to survey the reef habitat. Additional spot dive surveys were undertaken at northern side of East Cove, Garden Cove, Winter Cove, Squally Cove (Deal Island), northern and southern sides of West Cove (Erith Island) and north east and north west coasts of Dover Island. Divers recorded numbers of sea urchins (Centrostephanus rodgersii and Heliocidaris erythrogramma), as well as extent of urchin barrens, size of algal patches, and measured boundaries of macroalgal patches of Macrocystis angustifolia, Phyllospora comosa and Ecklonia radiata-fucoid communities. Spot dives detailed additional qualitative observations of C. rodgersii.