三峡库区鱼类群落结构现状及变化

Current Status and Changes in Fish Assemblages in the Three Gorges Reservoir

为了解三峡库区鱼类群落结构现状,于2017~2019年对三峡库区干流和9条重要支流开展鱼类种类组成调查,于2018年对库尾木洞、库中云阳和库首巫山干流江段开展渔业资源调查,同时结合历史资料进行了分析。共采集到鱼类149种,隶属于10目25科92属,其中长江上游特有鱼类30种,外来物种20种,喜流水鱼类67种,喜静缓流鱼类82种。研究表明:总物种数与水库运行前相比持平,但组成发生了较大变化;土著种和喜流水性鱼类显著减少,外来种增多;小型鱼类在资源量中占据优势,大中型鱼类资源退化;喜流水鱼类仅在库尾渔获物中占据优势,库中和库首江段渔获物以喜静缓流鱼类为主;干流特有种种类数和资源量均显著下降,支流仍分布有较多特有鱼类;外来种在库中和库首渔获物中占据一定比例,其大量繁衍和发展可能给该水域土著种的生存带来负面影响。三峡库区蓄水过程显著影响了鱼类群落结构。

In order to understand the current status of fish assemblages in the Three Gorges Reservoir,both species composition of fish in the mainstream and nine important tributaries of the Three Gorges Reservoir,and fishery resources in the upper(Mudong section),middle(Yunyang section)and lower(Wushan section)reservoir were investigated,from 2017 to 2019.The changes of fish assemblages before and after impoundment were also analyzed by comparing the present results with other published data.A total of 149 fish species,belonging to 10 orders,25 families and 92 genera,were collected in the Three Gorges Reservoir,of which 30 species were endemic to the upper reaches of the Yangtze River,20 species were exotic,67 species were rheophilic and 82 species were non-rheophilic.Compared with historical records of fish species before the impoundment of the Three Gorges Reservoir,the total number was similar.However,the species composition of fish has undergone a remarkable change after the impoundment.The number of both native and rheophilic species dropped notably,whereas that of exotic species increased remarkably.Small-sized fishes accounted for a great proportion in fish catches,while the catches of the middle and large sized fishes declined severely.Rheophilic species only dominated in the catches of the upper reservoir,while non-rheophilic species were dominant in the middle and lower reservoir.Both the number and resources of the endemic species were reduced significantly in the mainstream of the Three Gorges Reservoir,whereas a certain number of endemic species still exist in the tributaries.Exotic species constituted a considerable proportion of fish catches in the middle and lower sections of the reservoir,which suggests that the high abundance and dispersion of these alien species may bring noticeably negative influence to the survival of native species.In conclusion,fish assemblage of the Three Gorges Reservoir has been changed to a great extent by the impoundment.