The results come amid environmentalists' concerns that the fast industrial development in the region may have polluted the sea water and endangered the dolphins, which are sensitive to water quality.
But the research indicated that the water quality of the Beibu Gulf has remained of a high standard due to the local government's strict environmental policy and pollution supervision.
The dolphins are dubbed the "giant pandas in the sea" because of their rarity.
Animal experts believed that the number of the dolphins in south China's Pearl River Estuary, one of its major habitat, is no more than 1,000.
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