Walk through the noisy urban area of Yushu, check the infrared cameras deployed along the Batang River and Zhaqu River, and find the tracks of Eurasian otter... Zhao Xiang and his colleagues have been doing such work for more than 7 years. Yushu City is located in Yushu Tibetan Autonomous Prefecture, Qinghai Province, on the Qinghai Tibet Plateau. Batang River and Zhaqu River cross the city and finally flow into the upper reaches of the Yangtze River. In recent years, Eurasian otter has frequently appeared in local rivers and has become a famous "net celebrity". Zhao Xiang is the head of Shanshui Nature Conservation Center, a folk nature conservation organization, and has conducted field research in the Sanjiangyuan area for a long time. When we first found Eurasian otter, everyone was surprised. "Eurasian otter is regarded as an indicator species of river ecosystem and has high requirements for clean water quality. It is extremely rare to find Eurasian otter in densely populated urban areas," said Zhao Xiang. Since 2016, with the support of Yushu Municipal Government, the Mountain and Water Conservation Center has deployed nearly 500 infrared cameras in the Batang River and Zhaqu River basins to further study the population and living habits of local Eurasian otter. At present, it has independently taken more than 4200 images of Eurasian otter. The survey results show that there are 20 to 30 individual otters in Yushu City and surrounding waters, with good population density and survival status. Why are there so many Eurasian otter in downtown area? Zhao Xiang explained that Batang River and Zhaqu River are of good quality, rich in fish resources and healthy aquatic ecosystems, which are excellent natural habitats for Eurasian otter, which mainly eats fish. At the same time, the local people's awareness of ecological protection is also becoming stronger, creating a good atmosphere of harmonious coexistence between humans and nature. "Previously, we found small pieces of plastic in the feces of Eurasian otter. Over the years, with the improvement of river ecological Environmental remediation, garbage is almost invisible. Everyone has taken action to consciously protect Eurasian otter," said Zhao Xiang. The relevant person in charge of the Ecological Environment Bureau of Yushu City said that in recent years, Yushu City has continued to promote the construction of beautiful rivers and lakes, successively implemented the water conservation function improvement project of the Batang River basin, the Batang River (Jiegu Sewage Treatment Plant) pollution reduction and treatment project into the river, built a "monitoring+monitoring" platform along the Batang River, and the water quality of the sections of Tongtian River, Batang River and other major rivers flowing out of the city remained at or above Class II all the year round. Seeing the changes in ecology, Sangbao couldn't express his joy in his heart. Sangbao is 49 years old and lives in Batang Township, Yushu City. He has been with water since childhood, and the changes in the Batang River have touched his heart. "When I was young, some people in the countryside secretly hunted Eurasian otter, used otter skin to make clothes, and some people dumped garbage into the river. Slowly, the number of Eurasian otter in the river became less and less, and some fish disappeared." Before talking about it, Sang Bao couldn't help sighing. Later, Sangbao took the initiative to sign up as a fishery assistant patrol officer, responsible for patrolling about 8 kilometers of the Batang River. The protection work of vegetation greening, nationwide ban on fishing, ban on plastic production and waste reduction has been gradually implemented. Sang Bao saw that some fish that had disappeared for many years reappeared in the river, and more and more Eurasian otter also settled down. Previously, ecological deterioration drove animals away, but now ecological improvement has brought them in. Do you think this change is significant? "Sangbao said. Nowadays, in Yushu City, walking along the Batang River trail after meals has become a habit for many people