Ecology around the Yangtze River has improved even after the launch of hydropower projects nearby, according to an engineering expert, who refuted an earlier statement made by the river's fishery resources management suggesting that the projects have destroyed the ecosystem of one of the world's longest rivers.

Zhang Boting, a senior engineer from the China Society for Hydropower Engineering, made the remark on Sunday at the 2013 Hydropower Convention in Kunming, Yunnan Province, but admitted that construction of dams may affect the spawning migration of fish.

The World Wildlife Fund and the Yangtze River fishery resources management committee office which is supervised by the Ministry of Agriculture, had said in a joint report in August, that the intensive hydropower development has had a destructive impact on the ecosystem along the Yangtze River.

During their last expedition, scientists had found only 17 species of fish in the Jinsha River, one of the major headwaters of the Yangtze River, down from 143 species in the past. They said as many as 25 hydropower stations had been planned along the Jinsha River and the ecosystem was drastically changing.

According to Chen Yifeng, a research fellow with the Institute of Hydrobiology under the Chinese Academy of Sciences, the current assessment of hydropower stations is not thorough as it does not evaluate the long-term risk or the comprehensive impact a station could cast on a river. 

Half of the distinguished species in the Yangtze River have disappeared, according to the report.

"I agree with the conclusion of the report that the ecology along the Yangtze River has deteriorated significantly, but it is as a result of overfishing and water pollution," Zhang told the Global Times, adding that the hydropower projects benefit the ecosystem as artificial breeding has helped save some endangered species.

Zhang highlighted the usefulness of dams with the example of the Three Gorges Dam, the country's largest hydropower project that spans the Yangtze River, and said the dam had protected residents of downstream areas from a devastating flood in 2012. The flood had affected over 100 million people.

But according to Zhao Yimin, director of the Yangtze River fishery resources management committee office, fishes should not be sacrificed for the cause of economic development as knowledge of extinct species could be critical for future research.

"The species in the Yangtze River have gone through the evolution for thousands of years and many of them are unique to the river genetically," Zhao said. "They consist of a significant part of the ecological environment and can be made use of by humans later."

Zhao said he opposed the construction of hydropower projects in an "unconstrained and irregular pattern," as dams change the environment and accelerate extinction of some species.