瀑布沟水电站成库后鱼类组成变化与保护对策

通过探究瀑布沟水电站建成后鱼类物种结构与建库前的相应变化,为有针对性的生态补偿措施提供参考,还可为西部地区水电开发与自然生态保护的协调发展提供宏观决策依据。基于1985年、2002年和2012年在瀑布沟库尾至坝下河段的调查数据,研究了瀑布沟水电站水库形成前后库区鱼类物种组成、渔获物结构以及保护物种分布的变化趋势。2012年库区调查共采集到鱼类14种,相比1985年和2002年分别减少了53种和51种,群落组成中定居性鱼类物种比例及渔获物比例均显著上升,适应流水环境的鱼类所占比例大幅下降。渔获物中优势物种为鲫(Carassius auratus),占渔获总重量的比例为61.59%,而在前2次调查中占据优势的齐口裂腹鱼(Schizothorax prenanti)和重口裂腹鱼(Schizothorax davidi)几近消失。研究结果显示,水库形成后鱼类组成已发生显著改变,适应流水生境的鱼类在库区难以捕获,而静水性鱼类比例则显著升高;重口裂腹鱼等保护物种以及四川白甲鱼(Onychostoma angustistomata)等特有鱼类因水文条件的变化总体上表现为资源量下降,同时分布区域向坝下或库尾等流域生境迁移。针对成库后鱼类物种的变化特征,提出了实施生态保护、规划过鱼设施以及开展增殖放流等措施和建议。

Variation of Fish Composition after Impoundment of Pubugou Reservoir and Proposed Protection Strategy

Pubugou hydropower station is the twentieth of the cascaded hydropower stations on Dadu River. Construction began in 2001 and operation began in December, 2010. The variation of fishery structure, catch composition and distribution of protected species before and after the impoundment of the reservoir were studied based on fishery resource investigations carried out in May and September of 1985, 2002 and 2012. The study area extended 75 km, including the backwater, open reservoir and a tributary (Niri River) and methods included field investigations, assimilation of existing data and interview surveys. During the 2012 investigation, 14 fish species were collected in the reservoir area, a decrease of 53 species since 1985 and 51 species since 2002. The percentage of still water fish species in fish catches increased significantly, while fish species that prefer running water declined dramatically. The dominant species in fish catches was Carassius auratus, accounting for 61.59% of the total weight, but Schizothorax prenanti and Schizothorax davidi, dominant in the two earlier surveys had nearly disappeared in 2012. The species composition of the fish community in the reservoir changed significantly, from species inhabiting swift water to fish preferring static water. Because of the change in hydrology, protected species such as Schizothorax davidi and species endemic to the upper reaches of the Yangtze River such as Onychostoma angustistomata significantly decreased as their distribution moved downstream of the dam and to tail waters of the reservoir. Based on the current fishery resource situation in the reservoir area, protection strategies were proposed, including ecological protection, fishery stock enhancement and release, and planning fish passage facilities for migration.