The impacts of marine traffic on the Indo-Pacific humpback dolphins (Sousa chinensis) in Hong Kong waters

Abstract

Indo-Pacific humpback dolphin (Sousa chinensis) is one of the residential cetaceans in Hong Kong. It is threatened by different anthropogenic activities and one of the threats is the vessel disturbance. According to the past research studies and scientific data, the heavy marine traffic has caused negative impacts to the dolphins, by increasing the risk of boat collisions; creating a noisy environment within the dolphin habitats; causing short-term behavioural changes of dolphins and dolphins may have potential to displace from the Hong Kong waters in the long-term. The current conservation and mitigation measures are inadequate and ineffective towards this situation. An action plan is formulated based on the literature review of the practices from other countries and the results of the questionnaire survey. Mitigation measures such as speed restriction, re-routing or use of technology tools are common measures used by other countries such as the United States or Spain. From the results of the questionnaire survey, the high-speed ferry passengers were willing to spend 23.5 minutes more of their trips for a speed restriction or a longer ferry route in order to reduce the vessel impacts to the dolphins. At the same time, they were willing to pay for HKD 9.26 extra as a surcharge on the ferry fare to serve as a financial support to the dolphin or marine conservation in Hong Kong. It reflected the public had a high willingness to pay for the dolphin conservation in Hong Kong. The action plan summarized the practical mitigation measures according to these findings in order to suggest sound conservation and management measures to the related authorities to mitigate the impacts and to stop the declining trends of dolphin abundance in Hong Kong waters.