Status of aquatic organisms resources and their environments in Tibet (2017—2021)

Tibet is an important ecological and security barrier for our country. The ecological environment is fragile and difficult to recover once destroyed. In order to implement the national policy of focusing on protection rather than development, and to make agricultural aid to Tibet more accurate and pragmatic, The Chinese Academy of Fisheries Sciences has put forward a special proposal for a “Fishery source and environment survey of key waters in Xizang”, based on the characteristics of Xizang's fishery resources and environment. Field sampling and remote sensing monitoring were adopted to gain a comprehensive understanding the aquatic organisms and ecological environment in Tibet. Three institudes of Chinese Academy of Fishery Sciences ( Yangtze River Fisheries Research Institute, Heilongjiang Fisheries Research Institute, Fishery Resource and Environment Research Center) , Huazhong Agricultural University, Institute of Hydrobiology, Chinese Academy of Sciences, and Institute of Aquatic Science, Tibet Academy of Agriculture and Animal Husbandry Science surveyed fish species composition, fishes present abundance and status of fisheries ecological environment in the three rivers (Yarlung Zangbo River, Nujiang River, Lancang River) and four lakes (Basomtso Lake, Zhegu Lake, Lake Amdo Tsonak Co, Co Ngoin Lake). Results showed that 53 fish species were collected in three rivers and four lakes from 2017 to 2021, which belongs to 24 genus, 5 families, 2 orders, including 45 native fishes, 6 non-native fishes and 2 hybrids. Schizopygopsis younghusbandi, Ptychobarbus dipogon, Schizothorax oconnori, Oxygymnocypris stewartii were the dominant species in the upper reach of the Yarlung Zangbo River. S. oconnori, S. macropogon, S. younghusbandi, S. waltoni were the dominant species in the middle reach of the Yarlung Zangbo River. As national second-class protected animals, the weight proportion of Oxygymnocypris stewartii and Glyptosternum maculatum have been decreased significantly from the Sangri to Jiacha reach of middle Yarlung Zangbo River. S. curvilabiatus, Garra kempi, Sisoridae sulcatus, S. molesworthi, Psilorhynchus homaloptera were the dominant species in the lower reach of the Yarlung Zangbo River. Ptychobarbus kaznakovi, S. thermalis, S. nukiangensis were the dominant species in the Nujiang River. S. lissolabiatus and S. lantsangensis were the dominant species in the Lancang River. S. oconnori and S. macropogon were the dominant species in the Basomtso Lake. Triplophysa stewarti, Gymnocypris waddelli, S. younghusbandi were the dominant species in the Zhegu Lake. Both S. thermalis and T. stewarti were the dominant species in the Lake Amdo Tsonak Co and Co Ngoin Lake. The exotic Species were mainly distributed in the middle reach of the Yarlung Zangbo River. The water quality of the three rivers and four lakes basically met the water quality standards of the fishery. Concentrations of the total nitrogen and total phosphorus in the upper reaches of the Yarlung Zangbo River were lower than those in the middle and lower reaches of the Yarlung Zangbo River. Results suggested that the number of native fishes (45 species) which were collected in three rivers and four lakes in Tibet from 2017 to 2021 was 62.50% of the number of native fishes (72 species) before 2017. Both S. oconnori and S. younghusbandi were the dominant species in the middle and upper reaches of the Yarlung Zangbo River. The weight proportion of endangered O. stewartii and G. maculatum have been decreased significantly from the Sangri to Jiacha reach of middle Yarlung Zangbo River. The non-native fishes were mainly distributed in the middle reach of the Yarlung Zangbo River. The water quality of the three rivers and four lakes basically met the water quality standards of the fishery. This survey provides important scientific and technological support for Tibet's fishery resources and protection, sustainable utilization of unique resources and sustainable development of ecological environment.