Bottlenose dolphins of Montenegro: Abundance Estimation and Residency Patterns

The Bottlenose dolphin (Tursiops truncatus) suffers from the lack of research in the Southern Adriatic Sea. In 2012, a decline of 50% of bottlenose dolphins population in the Mediterranean Sea was reported. In order to further our understanding of the spatial ecology of bottlenose dolphins in the southern Adriatic Sea, a four-year photo-identification study (starting in 2016) was carried out in Montenegro. Our results showed no permanent residency in Montenegro of any identified individual. Despite the low site fidelity, certain individuals were sighted each year throughout the survey. Key natural habitats for bottlenose dolphins were found all along the Montenegrin coast with notable preferences for Ulcinj, Bar, and the Boka Kotorska Bay. Although the lack of data in the previous decade prevented us from inferring population trends, annual abundance estimation revealed a constant decline from 116±17 in 2017 to 79±21 in 2019. The current study provides critical information on the population status of bottlenose dolphins in Montenegro, with a worrying decline recorded between 2016 and 2019 which could be attributed to the natural causes and/or increased human activities in Montenegro, ranging from coastal destruction to oil and gas explorations. Future research has to assess the present threats on the species while following a transboundary approach to understand the home ranges of species and to investigate the presence of possible habitat shifts.