丹江口水库鱼类群落特征及其历史变化

Characteristics and historical changes of the fish assemblage in the Danjiangkou Reservoir

为了解丹江口水库鱼类群落现状及历史变化,作者于2018–2019年采用多网目复合刺网采样和渔民渔获物调查的方式对丹江口水库进行了鱼类群落调查。本次调查共采集鱼类33种,隶属5目11科29属,以鲤科鱼类为主,占总数的63.6%。基于多网目复合刺网采样的鱼类群落多样性指数和单位努力捕捞量(catch per unit effort,CPUE,g·day^(-1)·m^(-2))在各采样点间具有一定的差异。目前丹江口水库以定居性、喜静缓流、杂食性和肉食性鱼类为主。与20世纪50年代和80年代的历史资料相比,丹江口水库鱼类物种丰富度先升高后下降;而生态类型则呈现杂食性鱼类、喜流水性鱼类和洄游性鱼类比例持续下降的趋势。2018–2019年丹江口水库鱼类组成与20世纪80年代的相似性指数为0.35(中等不相似),与20世纪50年代的相似性指数为0.29(中等不相似)。调查结果表明半个世纪以来丹江口水库鱼类群落结构发生了较大变化,目前趋于小型化和简单化。这些变化可能是由大坝建设、渔业放养、不合理捕捞、外来鱼类引入等人类活动所致。

To quantify the fish assemblage and its historical change,we conducted surveys in the Danjiangkou Reservoir in 2018 and 2019 based on multi-mesh gillnet samplings and catch by fisheries.A total of 33 fish species were collected,belonging to 5 orders,11 families,and 29 genera,among which Cyprinidae were dominant,accounting for 63.6%of the total species captured.Spatial variation of diversity indices and catch per unit effort(CPUE,g·day-1·m-2)based on gillnet samplings were calculated among sampling sites.Currently,the Danjiangkou Reservoir is dominated by sedentary,lentic,omnivorous and carnivorous fishes.Compared with historical data from the 1950s and 1980s,the number of total fish species in the reservoir increased and then subsequently decreased.Whereas the proportion of omnivorous species,lotic species,and migratory species showed a continuous decline.The similarity indices of species composition between the present and the 1950s and 1980s were 0.35 and 0.29,respectively(both medium dissimilarity).These results indicate that the current fish assemblage in the Danjiangkou Reservoir has undergone significant changes in the last half-century trending toward smaller species and simpler assemblages,which may be attributed to human activities such as dam construction,fish stocking,overfishing,and the introduction of non-native fish species.