Signature whistles of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Fremantle Inner Harbour, Western Australia

A community of ~21 Indo-Pacific bottlenose dolphins (Tursiops aduncus), plus calves, resides in the Swan Canning Riverpark, Perth, Western Australia. A complete photo-identification catalogue has been maintained for close to a decade. Regular visual monitoring of individuals in this community can be laborious and expensive. Bottlenose dolphins elsewhere have been shown to emit so-called signature whistles, by which individual animals can be identified. Passive acoustic listening is an efficient monitoring tool in the marine environment and hence an attractive option for monitoring individuals within this small dolphin community-if individual photo-ID can be matched with signature whistles. Archived underwater acoustic recordings and photographs of individual dolphins at the surface were matched chronologically. Dolphins were always present in groups rather than individually. Consequently, to assess whether distinctive whistles could be associated with certain individuals, the likelihoods that catalogued individuals were present when specific whistle types were heard were computed by calculating the percentage of the total number of occasions individual dolphins were in the study area when the whistle was produced. While a larger sample size is needed to capture all individuals in diverse groupings, this study provides the first step in developing a passive acoustic monitoring program for individuals in this small community.