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Australian sea lion foraging ecology research, Bunda Cliffs, South Australia

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Australian sea lions are listed as endangered by the Australian Government EPBC Act. They are thought to be vulnerable to decline due to (i) already small overall population size (~17,000 animals), (ii) extended breeding cycle (17-18 months, which reduces lifetime fecundity), (iii) breeding site fidelity or philopatry (where adult females always return to their place of birth to breed, thus extinguishing the possibility of depressed or extinct breeding sights recovering), and (iv) genetically isolated and very small sub-populations (as a result of philopatry, with about one third of the ~70 breeding sites producing less than 30 pups each breeding cycle). One of the handful of known threats to the conservation of the species is by-catch mortality in demersal gill-nets set in South Australian shelf waters to catch large amounts of gummy and school shark, which makes up the bulk of fish used in the 'fish and chip' trade in southern Australia. About 86% of the species resides in South Australian waters, suggesting the two are likely to frequently overlap. The tracking by satellite transmitter of individual females provided valuable insights into where they go to forage when at sea. Overlapping their 'tracks' with data collected on the distribution of gill-net fishing effort enables the areas of particular concern to be identified. The results of the Bunda Cliffs deployments depicted in this video clip, along with the tracks of individuals tracked from more than 16 other breeding sites on islands adjacent to the South Australian mainland, have been used to inform managers on where a network of 'fishery exclusions' or 'spatial closures' should be placed. At present, the network of closures actually in place are based more on negotiated outcomes between stakeholders (i.e. conservation and fishery managers, each of whom have opposing legislative mandates). Working from the Bunda Cliffs posed the greatest challenge of any of the sights visited for this generally large and logistically difficult study. It's imposing 120m cliffs acted as a barrier to accessing the colony, with the only possible access over the edge. The professional approach of the local Ceduna SES Cliff Rescue team made that possible. The study was largely funded by FRDC, SARDI and NHT, with the GABMP-MC providing funds and in-kind support specifically for the Bunda Cliffs work. The project was coordinated by Dr Derek Hamer and the video clip itself was funded by the GABMP-MC and put together by ???.
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