Hong Kong Sha Chau and Lung Kwu Chau Marine Park, the 'Home' for the Indo-Pacific Humpback Dolphin (Sousa chinensis) ?

The Indo-Pacific Humpback Dolphin (Sousa chinensis), or Chinese White Dolphin is one of the two species of marine mammals found mainly in western Hong Kong waters.  Its habitat is under constant threat with rapid coastal economic development in Hong Kong.  The largest marine protected area (1200 hectares) – Sha Chau and Lung Kwu Chau Marine Park (SLMP) was established in November 1996 as part of a major effort to protect this species.  Ten years after, is it still a good home?

Seven sites in western Hong Kong are chosen as land-based observation stations for monthly dolphin monitoring surveys.  Among these, four sites are within SLMP and three are outside.  Apart from dolphin surveys, monthly fish surveys and traffic count are also conducted to evaluate food availability and traffic disturbance as possible factors that could affect the quality of these habitats.

Based on results from October 2005 to August 2006, a total of 183 sightings (391 dolphins) were observed in the seven sites. The shares of each of the fours sites in SLMP ranged from 9 – 17% of the total, which is much lower than 35% for Tai O (a site in the relatively undisturbed Lantau island) but higher than < 5% in the two other more urban sites. The monthly mean number of sightings was not significantly different among the sites within SLMP and the two urban sites. Moreover, the group size distribution, dive time and behavioral patterns were also not significantly different between sites within and outside SLMP. Besides, the chance of seeing a dolphin in two of the sites in the marine park is similar to the two urban sites, i.e. < 50%. Based on these results, the marine park is still serving as a reasonably good habitat for the dolphins.