Two species of small cetaceans, the Indo-Pacific hump-backed dolphin and the finless porpoise, occur year-round in waters of the Hong Kong Special Administrative Region. Research conducted from September 1995 to March 1998 has allowed for a preliminary assessment of the status of the finless porpoise population that occurs in Hong Kong. Line transect vessel surveys have been used to examine distribution and abundance, and a stranding recovery program provides information on mortality and life history.
Finless porpoises only occur in the southern and eastern waters of Hong Kong, away from the influence of the Pearl River. The area of southwest Lamma Island appears to be a “hot spot” in winter and spring months. There are seasonal shifts in abundance, with minimum estimates of numbers in the southern waters of Hong Kong ranging from a low of 27 in autumn to a high of 154 in spring. There are currently insufficient data to reliably estimate numbers in Hong Kong’s northeastern waters. It is likely that individuals move between Hong Kong and the surrounding waters of China’s Guangdong Province. Although aggregations of up to 17 porpoises have been seen, most groups are of less than four porpoises. Calving takes place between November and April, with a large peak in mid-winter. Several natural and human-related mortality factors have been identified. Trends in abundance are not yet known, but the high number of strandings signal cause for concern over the future status of the population. Further research over the next few years should clarify many remaining questions about the status of finless porpoises, and aid in the development and enactment of a conservation plan for this species in Hong Kong.