金沙江下游鱼类栖息地评估和保护优先级研究

为了给受金沙江下游水电开发影响的鱼类筛选合适的支流进行栖息地保护，对金沙江下游12条支流进行了鱼类栖息地评估和保护优先级的研究。通过河段分类-河段样方调查-河流整体评估的路线评估了支流栖息地质量；通过2次流动调查，结合历史资料获取了各支流的特有鱼类种数；最后，结合栖息地评估结果、各支流的特有鱼类种数、年径流量和水电开发强度，运用分层排序法，得出了各支流的保护优先级，由高到低依次为：牛栏江>西溪河>黑水河>普渡河>龙川江>鲹鱼河>西宁河>美姑河>以礼河>普隆河>勐果河>小江。建议将乌东德库区的龙川江和鲹鱼河、白鹤滩库区的黑水河和普渡河、溪洛渡库区的牛栏江和西溪河，以及向家坝库区的西宁河作为金沙江下游鱼类优先保护支流

HABITAT ASSESSMENT AND CONSERVATION PRIORITY FOR FISHES IN THE LOWER JINSHA RIVER

Dam construction is a major threat of human activities to freshwater fish species. River damming often leads to habitat segregation, degradation and loss, and ultimately extirpates some aboriginal fish species. Four large cascade dams (Wudongde, Baihetan, Xiluodu and Xiangjiaba) are being built or will be built in the future in the lower reach of the Jinsha River. Many fish species in the Lower Jinsha River are likely to be threatened by the impoundment because of the tremendous change of their habitats. Moreover, among these fishes, some endemic fishes of the Upper Yangtze River need the rapidly flowing tributaries of the Lower Jinsha River as substitute habitats to spawn and survive. In order to optimize the utilization of limited habitat resources to conserve the fish species threatened by the cascade dams, the present study assessed the fish habitats of 12 tributaries of the Lower Jinsha River and set their conservation priorities based on habitat evaluation and other related concerns. The habitat evaluation was realized based on a new method combining spatial data analysis and field surveys. Firstly, at the reach (approximately10 km) level, 168 reaches of the 12 tributaries were classified into 9 groups on the basis of seven criteria: gradient, altitude, width, reach order, sinuosity, riparian vegetation index and dam construction status. Spatial data of these criteria was derived from Spot Maps in the Google Earth and digital elevation map and land cover map in the Geographical Information System. Secondly, several reach samples of each identified reach group were surveyed in the field at the microhabitat level using an adjusted qualitative habitat evaluation index derived from the original version of the Environmental Protection Agency of the United States. Thirdly, each reach group was scored using a weighted mean method, and subsequently each tributary was evaluated with the same approach. On the other hand, twice recent fish samplings were conducted in some reaches of several tributaries. The surveyed and historical fish sampling data was then used to determine the richness of endemic fish species in each tributary. Finally, the habitat evaluation results, the richness of endemic fish species, the annual runoff and the total number of dams were used to set the conservation priority of each tributary with a hierarchical ranking method. The all 12 tributaries were ranked by their priorities as follows: Niu lan > Xi xi > Hei shui > Pu du > Long chuan > Can yu > Xi ning > Mei gu > Yi li > Pu long > Meng guo > Xiao jiang. In order to conserve at least one to two tributaries in each of the four future reservoirs, seven tributaries were chosen according to the ranking list. These tributaries were: Long chuan and Can yu in the Wudongde Reservoir, Hei shui and Pu de in the Baihetan Reservoir, Niu lan and Xi xi in the Xiluodu Reservoir, and Xi ning in the Xiangjiaba Reservoir. To conserve fishes in these tributaries, reaches with high habitat qualities should also be first protected. Specific conservation policies and projects on these priority tributaries should be designed in the not too distant future