水电工程建设前后外来鱼类入侵问题初步研究

Preliminary study on invasion of alien fish species after construction of hydropower projects

随着我国水电工程建设的不断推进,工程建设和运行中产生的外来鱼类入侵问题受到越来越多的关注。以研究资料较为丰富的雅砻江二滩库区、长江三峡库区、黄河上游龙羊峡至刘家峡河段作为典型研究区域,系统梳理了库区河段外来鱼类的种类组成、资源量、生态特征和引种途径等。研究发现:库区外来鱼类中的经济鱼类主要由人为有意引种而引入,而小型鱼类主要是人类无意引种而带入;水库蓄水初期库区河段由于水动力学过程变化和营养盐输入增加,库区水体初级生产力大幅提高,这为外来鱼类的定植和扩散提供了丰富的饵料来源;外来鱼类进入库区后通过与土著鱼类竞争饵料资源和生活空间、破坏土著鱼类的种群补充、污染土著鱼类的种质资源等,造成库区河段土著鱼类的种类和种群数量显著下降。为降低外来鱼类造成的生态危害,提出了严控人为引种和传播、及时预警和监测、加强土著鱼类保护、降低外来鱼类种群数量等对策措施。

Along with the development of hydropower project construction in China,invasion of alien fish species caused by hydropower project construction and operation has raised more and more attentions. Taking Ertan Reservoir area of the Yalong River,the Three Gorges Reservoir area of the Yangtze River and the Longyangxia to Liujiaxia reach in the upper Yellow River as typical cases,the species composition,resource quantity,ecological characteristics and invasion ways of the alien fishes were systematically analyzed. The study found that the economic exotic fishes were mainly introduced intentionally,while small-sized fish were mainly introduced unintentionally. In the early stage of impoundment,the reservoir primary productivity was greatly improved due to the change of water dynamic process and the increase of nutrient input,and thus provided a rich source of feed for colonization and spread of alien fish. When alien fish entered the reservoir area,they significantly reduced the number and population of indigenous fish species by competing food resources and living space,destroying population supplement,and polluting the germplasm resource of indigenous fishes. Finally,we put forward some countermeasures to alleviate these negative ecological effects,such as strictly controlling artificial introduction,early warning and monitoring,strengthening the protection of indigenous fish and reducing alien fish populations.