Using ecotourism vessels as platforms for determining important habitats of bottlenose dolphins in Port Phillip Bay, south-eastern Australia

Understanding species critical habitat requirements is crucial for effective conservation management. However, such information can be challenging to obtain, particularly for highly mobile, wide-ranging species such as cetaceans. In the absence of systematic surveys alternative economically viable methods are needed, such as the use of data collected from platforms of opportunity, and modelling techniques to predict species distribution in unsurveyed areas. The present study uses data collected by ecotours and other vessels of opportunity to investigate important habitats of a small, poorly studied population of bottlenose dolphins in Port Phillip Bay, south-eastern Australia. Using 16 years of dolphin location data, presence-only (Maxent) and presence-absence (GAMM) habitat suitability models were built, from which environmental factors influencing dolphin distribution were identified. Maxent results indicated that important habitats were those areas close to coastlines and shipping channels, with these factors contributing a large proportion (>71.3%) to the variation in the likelihood of dolphin presence. In contrast, GAMM results identified important habitats close to areas with seagrass beds and rocky reefs. However, despite factors having a significant effect (P < 0.05), the model only explained a small proportion of the overall variation (<10%). The high performance of the Maxent model suggests that simpler citizen science data collection may be sufficient for predicting the species distribution. However, additional data from the centre of Port Phillip Bay is required to support this contention. Important habitat features from the study are likely to relate to favourable foraging conditions for dolphins as they are known to provide feeding, breeding, and spawning habitat for a diverse range of fish and cephalopod prey species. The results of the present study highlight the importance of affordable community-based data collection such as ecotour vessels and citizen scientists, for obtaining information critical for effective management.