An 18-year time series of Australian fur seal diet in Bass Strait

Systematically monitoring the diet of large marine predators may be an effective approach to detecting changes within an ecosystem. The Bass Strait marine ecosystem is predicted to be most vulnerable to long term... [ view full abstract ]

Systematically monitoring the diet of large marine predators may be an effective approach to detecting changes within an ecosystem. The Bass Strait marine ecosystem is predicted to be most vulnerable to long term environmental change as it is a hotspot for warming coastal waters. We investigate the diet composition of Australian fur seals at Seal Rocks in central Bass Strait over the past eighteen years. Through hard part analysis of 6805 scat and regurgitate samples, 67 prey species were identified and their frequency of occurrence determined on an annual basis. Prey size was estimated by measuring 2084 intact, non-degraded otoliths (fish ear bones). The diet composition of prey species varied over the course of the time series with individual species varying in presence and predominance. A generalised additive model will be used to investigate the influence of environmental variation on the frequency of occurrence of prey species and any variation in prey size. Ultimately this will improve predictions in response to likely future changes facing large marine predators within the Bass Strait marine ecosystem.