Investigating the spatial interactions between marine traffic and bottlenose dolphins (Tursiops truncatus) within the coastal waters of Montenegro, South Adriatic Sea

Investigating the interactions between cetaceans and marine traffic provides us invaluable insight into the extremity of this anthropogenic disturbance. Studying on a spatial scale will allow the identification of key areas where strategic protection must be implemented. The data deficient waters of Montenegro are an important area for bottlenose dolphins (Tursiops truncatus) within the Southern Adriatic Sea. This region faces prevalent boating due to a booming tourism industry and traditional fishery activities, reinforcing the necessity of persistent research and conservation efforts. The current study is Montenegro's only dedicated long-term research effort on cetaceans, with the aim to understand the spatial interaction between bottlenose dolphins and marine traffic. Between 2016 and 2021, data was collected across the coastline of Montenegro through 644 land-based surveys with theodolite stations. During this research effort, dolphins were observed during 187 surveys. The potential effect of vessel density and vessel proximity on dolphin presence as well as the area preference of bottlenose dolphins were investigated. Results indicated that the BokaKotorska was a key area of presence, and that dolphins remained at sites despite there being increasing vessel density. It is important to highlight that <20% of marine vessels observed were within the zone of disturbance (<400m) of focal groups. The results suggest that the coastal waters of Montenegro hold important bottlenose dolphin habitats, with the indication that the ecological benefits of these waters outweigh the cost of marine vessel disturbance. It is key to mention that dolphins are consistently displaying instantaneous marine vessel avoidance across every region of the coastline, emphasizing their negative response towards marine traffic disturbance. Delphinids in Montenegro's coastal waters have exhibited area preference to BokaKotorska, yet this bay has the highest marine vessel density, therefore effective conservation management strategies must be curated for this area and implemented successfully.