A finless porpoise swims in the Yangtze River in Yichang, central China's Hubei Province, Aug. 3, 2020. The finless porpoise, an endemic species in China, is an important indicator of the ecology of the Yangtze. (Photo by Lei Yong/Xinhua)

A finless porpoise swims in the Yangtze River in Yichang, central China's Hubei Province, Aug. 3, 2020. The finless porpoise, an endemic species in China, is an important indicator of the ecology of the Yangtze. (Photo by Lei Yong/Xinhua)

A finless porpoise swims in the Yangtze River in Yichang, central China's Hubei Province, Aug. 3, 2020. The finless porpoise, an endemic species in China, is an important indicator of the ecology of the Yangtze. (Photo by Wang Gang/Xinhua)

A finless porpoise is seen in the Yangtze River in Yichang, central China's Hubei Province, Aug. 3, 2020. The finless porpoise, an endemic species in China, is an important indicator of the ecology of the Yangtze. (Photo by Lei Yong/Xinhua)

Finless porpoises swim in the Yangtze River in Yichang, central China's Hubei Province, Aug. 3, 2020. The finless porpoise, an endemic species in China, is an important indicator of the ecology of the Yangtze. (Photo by Lei Yong/Xinhua)