三峡水库高、低水位下汉丰湖鱼类资源变化特征

Variation in the Hanfeng Lake Fishery Resource between Low and High Water Levels in Three Gorges Reservoir

2012年10-11月三峡水库高水位期以及2013年5-6月三峡水库低水位期调查了汉丰湖的鱼类资源,研究三峡水库高、低水位下汉丰湖鱼类种类组成、优势种类、生物多样性以及群落相似性,并对不同水位下汉丰湖鱼类群落结构的扰动特征和增殖放流情况进行了辨识和探讨。共采集到鱼类17 553尾,42种,隶属于4目7科31属。其中三峡水库低水位时采集到鱼类33种,高水位时采集到鱼类34种。汉丰湖优势种类在三峡水库低水位时为银鮈Squalidus argentatus、似鳊Pseudobrama simoni、歺又鱼Hemiculter leucisculus、蒙古鲌Culter mongolicus mongolicus和鲤Cyprinus(Cyprinus)carpio;在三峡水库高水位时为似鳊、鲤、鲫Carassius auratus、张氏歺又鱼Hemiculter tchangi和鲇Silurus asotus。汉丰湖鱼类Shannon-wiener多样性指数(H')、Simpson优势度指数(D)、Pielous均匀度指数(E)和Margalef种类丰富度指数(R)在三峡水库低水位时分别为1.63、0.67、0.46和3.52;在三峡水库高水位时分别为2.15、0.80、0.61和4.34。三峡水库低、高水位时汉丰湖鱼类群落结构的Bray-Curtis相似性仅为26.52%,喜缓、静水生境的银鮈、张氏歺又鱼、鲤、歺又鱼、鲫、鲇、似鳊和蒙古鲌是群落结构差异的主要种类,累积差异贡献率为90.67%。汉丰湖鱼类群落在高水位时受到中等程度的干扰,而在低水位时受到严重干扰。建议每年均放流鲢、鳙、草鱼并进一步加大放流规模。

Hanfeng Lake is located in the Xiaojiang River backwater area of Three Georges Reservoir（ TGR） and its impoundment is synchronous with TGR： dry season from late May to early September and wet season from late October to early May. Water level regulation in Hanfeng Lake,through a dam and sluice gate,is used to mitigate the eco-environmental influence of water-level fluctuations in Three Gorges Reservoir on Kai County and the surrounding area. Water level regulation is also used to address environmental problems including changes in the aquatic environment,the dynamic balance of water and silt,and species migration in the Xiaojiang River basin.Fish population is of great importance for indicating the stability of aquatic ecosystem structure and function and also reflects the effect of fish breeding and release in the region. In this study we investigated the fishery resource in Hanfeng Lake during October and November of 2012 and in May and June of 2013,periods representing low and high water levels in Three Georges Reservoir. The three sampling sites selected were located in Hanfeng Lake and its two tributaries（ Donghe River and Nanhe River） and the investigation was carried out according to the Investigation Handbook of Fisheries Natural Resources in Inland Waters. Fish were captured by fishermen with three layer gill nets,hooks,electro-shocking,and bamboo cages. Species identification and body length and weight measurements of the fish collected were determined on site. This data was used to determine species composition,dominant species and biodiversity. Disturbance characteristics of the fish community structure and the effect of fish release program on Hanfeng Lake were identified and discussed. A total of 17 553 fish from 42 species,31 genera,7 families and 4 orders were observed： 33 species when TGR water level was low and 34 species when TGR water level was high. The dominant fish species in Hanfeng Lake differed significantly between different TGR water levels; Squalidus argentatus,Pseudobrama simoni,Hemiculter leucisculus,Culter mongolicus mongolicus and Cyprinus（ Cyprinus） carpio dominated when the water level was low,while Pseudobrama simoni,Cyprinus（ Cyprinus） carpio,Carassius auratu,Hemiculter tchangi and Silurus asotus dominated when water level was high. The Shannon-wiener diversity index,Simpson dominance index,Pielou evenness index and Margalef richness index of fish in Hanfeng Lake at high water in TGR were all higher than those at low water. The fish community structure of Hanfeng Lake displayed seasonal differences,with a Bray-Curtis similarity of only 26. 52% during the high and low water levels.Squalidus argentatus（ Sauvage et Dabry）,Hemiculter tchangi,Cyprinus（ Cyprinus） carpio,Hemiculter leucisculus,Carassius auratus,Silurus asotus,Pseudobrama simoni,Culter mongolicus mongolicus,species that prefer slow moving or static water,were the main species producing the observed differences in fish community structure,with a cumulative contribution of 90. 67%. Abundance Biomass Comparison（ ABC） shows that the fish community suffered moderate disturbance when TGR water level was high and a more serious disturbance at low water level. Overall,the fishery resource of Hanfeng Lake at high TGR water level is better than when the water level is low. Based on these results,we suggest that species richness and fish abundance will benefit from an expanded breeding and release program at Hanfeng Lake,especially an increased release of silver carp,bighead carp and grass carp.