A total of 22 Chinese white dolphins, also called Sousa Chinensis or Indo-Pacific humpback dolphins, died last year in southeast China's Pearl River estuary, according to Chen Jialin, Chief Director of the Pearl River Estuary Chinese White Dolphin National Nature Reserve.

The undated photo shows two Chinese white dolphins in the ocean. [File photo]

This is two to three times the number of dolphins that died during the same period last year, the "Information Times" reports.

Deteriorating weather was responsible for the deaths of the dolphins, including five of the 11 Chinese white dolphins which were young calves, Chen said.

The 1.2 to 1.4 meters-long young Chinese white dolphins that were still weaning died of starvation when storms and typhoons separated them from their mothers.

Land-based pollution was another reason for the deaths of the dolphins, Chen said. Figures released by his agency in May 2009 indicated that the total amount of pollution emitted into the ocean was nearly 530,000 tons; about 410,000 tons went into the Pearl River estuary. The polluted water made it difficult for the dolphins to find healthy food, which in turn caused diseases and deaths.

Underwater explosions, collisions with boats and entrapment in fishing nets also killed some of the Chinese white dolphins, Chen said.

The dolphins, which are called "pandas in the ocean" in China, are one of the rarest species of their kind. They give birth every three years, after which only a few survive. No more than 1,000 Chinese white dolphins now remain in the Pearl River estuary.