| Qin Ling thin scale's salmon (Brachymystax lenok tsinlingensis) distributing in the west part of Qin Ling mountain, famous for its thin squama, belongs to Brachymystax of Salmonidae in Salmoniformes. In general, it is named Mei Huayu in Chinese and Qin Ling thin scale's salmon in English. It was first discovered in Shaanxi Province of China in 1963. By studying more than 40 thin scale's salmon samples from the east and south of Taibai Mountain in 1966, Li Sizhong cogni-zanced that the fishes must be a subspecies of thin scale's salmon.Qin Ling thin scale's salmon, which was discovered late, hasn't got enough at-tention from the researchers. Papers about this study are few especially the study of the species in Gan Su province. In order to get the information of its wealth, habitat, protected grade, and endanger cause of Qin Ling thin scale's salmon, the present study has got detailed information of the basic materials by carrying out field inves-tigation, interviews, satellite graph analysis and so forth.This paper has done a systematic study on Qin Ling thin scale's salmon from the perspective of biology and ecology.The present study proves that the shape of Qin Ling thin scale's salmon has four characteristics--its thin squama, adipose fin, circular spots which look like clubs, and tiny tooth on mandible, vomer, palatine bone, and tongue. Qin Ling thin scale's salmon belongs to predacious fishes. Aquatic invertebrate is their main food. They activated frequently at the nights and in the morning because they fear light. In Gansu province, the period of population reproduce is in April or May every year.Qin Ling thin scale's salmon,which is a typical species of the narrow domain, being closed in the upper reaches of the Weihe River, forms dozens of small isolated populations. In Shaanxi province, its main distribution area is anabranches of Weihe River, including Qian He River (Longxian), Shi Tou He River (Taibaixian), Tangyuhe (Meixian), Heihe (Zhouzhixian), Shibianyuhe (Chang'an), and north anabranches of Hanshui River, including Taibaihe (Taibaixian), Xueshuihe (Taibaixian), Ziwuhe (Fupingxian). In Gansu province, the main distribution area is in the east of Gansu province, according to their degree of geographical isolation, the whole area is meas-ured into 21 small isolative zone (including, Zhangxian 1,Weiyuan 1, Minxian 5, Wushan 2, Gangu 5,Tianshui 1, Zhangjiachuan 6) . The length of the distribution river is 208.42km, and drainage area is 875.23km2, accounting 1.38%.of the whole area.Qin Ling thin scale's salmon, a typical cold-water fish, have more stringent re-quirements about their habitats. High vegetation coverage, enough soil water, less growing land, no pesticide pollution, high quality water, fast flowing stream of river with the drop high (average gap gradient ratio is 54), more oxygen in the river. The place where the salmon often escape and hide is the swallet formed by huge stones, the cave formed by the current rush on the river bed and the pore formed by the tree root. The vegetation along the river is mainly arbors and shrubs, which is good for the covering of the light.By doing the analysis of population age structure, comparison of distribution da-tum and discussion of the changes trends of the Gansu population, the study finds that the population of Qin Ling thin scale's salmon in Gansu is continuously declining; among 21 small species, three species are of high degree of risk.In recent decades, resources of Qin Ling thin scale's salmon are declining seri-ously. The survey shows that the first endangered cause was the habitat loss or degra-dation, the second one is excessive hunting. After the survey, the present study pro-vides several feasible protection measures. |
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