A large number of wild fish have been found floating dead in the Damuyang Sea waters of East China Sea over the past two weeks with initial studies indicating the deaths might be due to dramatic changes in hydrologic conditions in the sea.
The dead fish were found spread over an area of roughly 600 square kilometres.
The species affected mainly include spotted maigre, shark and large yellow croaker. Spotted maigre were the largest group.
Lying off the Juexi Town of Ningbo City, Damuyang Sea is a traditional fishing farm for large yellow croaker.
Local fishermen first spotted dead fishes scattered sparsely on the waters of the Damuyang on August 1.
The next day the number of dead fish had risen dramatically and more fish corpses appeared on the sea in the following days
"An investigation panel was dispatched to find out the truth of the case as soon as we were informed that the local fishermen had found a large number fish popping up dead on the waters of the Damuyang Sea on August 2,'' said Luo Feiqiang, director of the Ocean Resource Exploration Department under the Ocean and Aquatic Bureau of Ningbo City.
The panel consists of more than 20 members including professors from Ningbo University and Xiamen University and researchers with the Ocean Environmental Monitoring Centre of Ningbo City.
The investigation panel made two trips to the troubled waters of the Damuyang Sea but failed to find a clear explanation for the deaths.
Mr Wang Guoliang, a professor specializing in fish disease study with Ningbo University, did manage to successfully isolate an unidentified bacteria from some of the dying spotted maigres but he was not sure that the bacteria were responsible.
"Taking other elements into consideration, I doubt the bacteria is the real cause of the massive death of the fish,'' Wang said, explaining that other fish belonging to the same family of the spotted maigre managed to survive despite the presence of the bacteria in their blood.
Mr Zhou Zhanping, director of the Ocean Environmental Monitoring Center of Ningbo City echoed Wang's statement: "I don't think disease and pollution are the most probable causes of the massive death.''
"Historical recordings show pollution would not affect such a wide sea area,''Zhou continued.
Statistics collected on the spot indicated no large scale infectious fish disease, he added.
The investigation panel was told by the local fishermen that the spotted maigres were very sensitive to vibration and that dramatic vibration of the waters would force them to surface on the water and maybe even die.
Zhou speculated that the massive die off of fish in the area might be caused by unusual crust activity on the ocean floor.
"We will continue to probe into the case together with other experts and scholars. And I hope we will work out a satisfactory answer to the problem soon,'' he said.
(China Daily 08/15/2001)
