Osterrieder, Sylvia K (2016) Conservation ecology and human disturbance of Australian sea lions (Neophoca cinerea) in Western Australia. PhD thesis, Victoria University.

Abstract

Effective conservation and management are paramount to long-term recovery of endangered species. Achieving recovery relies on knowledge of their behaviour and habitats. Neophoca cinerea (Australian sea lion) is an endangered species endemic to Australia. This study focused on three key questions aimed at improving its management near Perth (Western Australia): testing a sea lion identification tool, describing haul-out patterns, and identifying human disturbance sources. N. cinerea whisker spot patterns as a tool for individual identification were tested using Chamfer distance-transform. Patterns contained sufficient information to reliably (99%) identify individuals in populations of 50, matching 90% correctly when testing known captive animals photographed at 90°. Off-angle photographs resulted in 48% correct matches. Resighting in the wild proved unfeasible in this study. However, resights of four scarred N. cinerea at Carnac and Seal Islands (the main study sites) confirmed returns and visitations to both islands. To describe haul-out patterns, generalized additive models were applied to hourly counts between 0800h- 1600h. N. cinerea numbers followed 17-18 month cycles, inversely aligned with the breeding cycle. During non-breeding seasons, hauled-out numbers increased throughout the day, and were associated with air temperature and tide. Research investigating human disturbance indicated that all human activity types elicited responses, which varied between islands depending upon stimulus types (vessel types, people), ranges to stimuli, and activities at each islands. People at close range elicited most elevated responses, including aggression and retreating. This occurred mainly at Carnac Island since direct beach access is allowed. Significant rates of lower-level disturbances were also elicited by vessels within close proximity, including paddlers and those undertaking noisy activities. Resulting recommendations include further restriction and enforcement in approach distances allowed. Also, ongoing monitoring of abundance and behaviour is required for long-term trend estimation. Because of high variability in haul-out behaviour, surveys undertaken at comparable times are recommended.

Search Google Scholar

Repository staff login