While Hong Kong, Macau, Guangzhou and other peripheral cities of the Pearl River Delta are integrating into a mega-regional economy, the vessel traffic on the cetacean occupied water and hence the pressure on resident dolphins will inevitably increase in the future. Because traffic disturbance may cause behavioral disruption that would be detrimental to the welfare of the animals, understanding the dynamics between dolphin behavior and vessel traffic is essential for proper management and conservation of the cetacean community. With this in mind, a series of land-based surveys were conducted at two selected vantage points of known dolphin abundance