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A Review of the Status of the Indo-Pacific Humpback Dolphin (Sousa chinensis) in Chinese Waters
Abstract: The status of Indo-Pacific humpback dolphins (Sousa chinensis) in Chinese waters (including Taiwan) is reviewed. Within China, humpback dolphins range from the Vietnam border north to the mouth of the Yangtze River, and there are estimated to be about eight populations in China. Little is known of stock structure, except for a preliminary conclusion that animals in Xiamen and Hong Kong represent separate populations. Abundance has been estimated only for Hong Kong and the Pearl River Estuary (about 1,500 animals) and Xiamen (80 dolphins). In the early 1960s, 36 animals were killed in Xiamen Harbor, but other direct takes appear to be rare. Incidental catches are known in Hong Kong and the Pearl River Estuary, but their impacts are not known. Only preliminary work on life history has been conducted. There appears to be a calving peak from spring to summer, and calves are about 100 cm long at birth. Scant data indicate that sexual maturity in females may occur at about 9-10 years of age, with males maturing later. Dolphins in Hong Kong and the Pearl River Estuary have individual ranges averaging 99.5 km2, only a small portion of the population’s range. Humpback dolphins in China feed on several species of demersal and estuarine fishes, with little evidence of predation on cephalopods or crustaceans. Contaminants have been evaluated in some areas, and mercury and DDT concentrations in particular appear to be high and potentially health-threatening. An assessment of trends and stranding mortality in the Hong Kong and the Pearl River Estuary population suggests that this stock is probably not decreasing at present. The Xiamen stock is thought to be decreasing, but its status has not been reliably assessed. Essentially, nothing is known of the status of other populations in China, and this shortcoming should be addressed as a matter of priority.
Key Words: CHINA; CHINESE WHITE DOLPHIN; HONG KONG; INDO-PACIFIC HUMPBACK DOLPHIN; REVIEW; SOUSA CHINENSIS; SOUTHEAST ASIA; STATUS
Document Type: Research Article
Page Numbers: 149-158