大宁河龙溪段鱼类早期资源现状及其与环境因子的关系研究

Status of Early-Stage Fish Resources in the Longxi Section of Daning River and Its Relationship with Environmental Factors

研究大宁河鱼类早期资源及其与环境因子的关系,为生态调度等鱼类资源保护措施提供参考。调查时间为2020和2021年,采样断面为三峡库区支流大宁河回水末端的龙溪断面,每年5-7月每日早、晚各采集1次。2020-2021年采样期共采集到24种鱼的卵412粒、仔稚鱼1074尾;2020年鱼卵、鱼苗平均漂流密度分别为0.852×10^(-3)粒/m^(3)、2.141×10^(-3)尾/m^(3);2021年鱼卵、鱼苗平均漂流密度分别为1.268×10^(-3)粒/m^(3)、2.925×10^(-3)尾/m^(3)。2020年调查期间,通过龙溪江段的卵苗径流量分别为166136粒、629781尾;2021年调查期间,通过龙溪江段卵苗径流量分别为351867粒、988608尾。RDA分析结果显示,中华纹胸鮡(Glyptothorax sinensis)、张氏䱗(Hemiculter tchangi)鱼卵漂流密度与水温变化呈现一定相关性,适宜水温促使产卵;随着流速和流量增加,多鳞白甲鱼(Scaphesthes macrolepis)和云南盘鮈(Discogobio yunnanensis)卵漂流密度均相应增加;大眼鳜(Siniperca kneri)和峨眉后平鳅(Metahomaloptera omeiensis)产卵期间江水酸碱度相对较低。建议采取生态调度、增加鱼类保护区等措施来保护大宁河鱼类资源。

Studing the early-stage fish resources of fish in the Daning River and their relationship with environmental factors could provide reference for measures to protect fish resources.In this study,we explored the changes in early-stage fish resources in the Daning River before and one year after the implementation of a ten-year fishing ban and analyzed the response of fish spawning to changes in environmental conditions,aiming to provide a reference for fish resource protection in Daning River.The study was based on surveys conducted in 2020 and 2021,before and one year after implementation of the ten-year fishing ban.The section of Daning River sampled was the Longxi reach at the end of the backwater from Three Gorges Reservoir.From May to July of 2020 and 2021,monitoring of early-stage fish resources was carried out in the morning and evening.The data recorded included sampling time,quantity of fish eggs and fry,developmental stages of the fry,and the species of all eggs and fry.Water environmental factors were determined simultaneously,in⁃cluding transparency as Secchi depth(SD),dissolved oxygen(DO),water temperature(T),pH,wa⁃ter velocity(V),and water flow(Q).A total of 412 fish eggs and 1074 larvae representing 24 fish species were collected during the investigation,including 115 eggs from 7 species and 359 larvae from 12 fish species in 2020,and 297 eggs from 9 species and 715 larvae from 20 fish species in 2021.The average density of drifting fish eggs and larvae were 0.852×10^(-3)eggs/m^(3),2.141×10^(-3)lar⁃vae/m^(3)in 2020 and 1.268×10^(-3)eggs/m^(3),2.925×10^(-3)larvae/m^(3)in 2021.The runoff of fish eggs and larvae passing through the Longxi study section was 166136 eggs/m^(3)and 629781 larvae/m^(3)in 2020,and 351867 eggs/m^(3)and 988608 larvae/m^(3)in 2021,respectively.Redundancy analysis(RDA)shows that the density of drifting Glyptothorax sinensis and Hemiculter tchangi eggs was correlated with water temperature.A suitable water temperature promotes spawning of Glyptothorax sinensis and Hemiculter tchangi.The density of drifting eggs from Scaphesthes macrolepis and Dis⁃cogobio yunnanensis both increased with velocity and flow.The acidity and alkalinity of river water were relatively low during the spawning period of Siniperca kneri and Metahomaloptera omeiensis.It is recommended to conduct ecological operation and increase fish conservation areas to protect the fish resources in the Daning River.