Long-term trends in cetacean incidents in New South Wales, Australia

This study provides an account of cetacean incidents in New South Wales, Australia. Incidents comprise reports of carcasses, injured and debilitated animals found stranded onshore, entrapped in shallow water, entangled or floating offshore. Marine mammal incidents were reported to the New South Wales National Parks and Wildlife Service (NSW NPWS) and recorded into the NSW NPWS Marine Fauna Events Database. Cetacean incident data was used to look for trends in cetacean mortality and debilitation, and baseline information on population dynamics including age and sex ratios. The database contains 891 cetacean records between 1790 and 2013. There were 33 cetacean species reported into the database, consistent with the known species richness of cetaceans in NSW waters. Incidents were categorised into one of 14 types. The cause of mortality or morbidity could not be established for the majority of cases. However, more incidents were related to anthropogenic causes (e.g. entanglements, vessel strike) than natural causes (e.g. disease, calf mortality). The largest known cause of incidents was entangled cetaceans (134 individuals), most of which were Humpback Whales caught in fishing gear. The results of this study highlight the utility of cetacean incident data for monitoring changing population dynamics and quantifying the magnitude of key threatening processes. Improved consistency in reporting over time has greatly improved the value of the database as a conservation monitoring tool.