长江中游-洞庭湖水系鱼卵、仔幼鱼洄游格局研究

Dongting Lake is one of the two largest river-connected lakes; it plays an important role as feeding ground for migratory fishes. Over the past few years, the natural flow regime of the middle reaches of Yangtze River-Dongting Lake system has been altered significantly due to the construction of water conservancy project and other anthropogenic activities, the alteration would affect the life history of river-lake migratory fish inevitably; the proposed Songzikou project makes the research on migration pattern of fish become more urgent. However, the related research been rarely carried out. In the present research，survey will be carried out in crucial migratory passage (Songzi River, Chenglingji and lower section of Xiangjiang River). The diurnal and seasonal dynamics of eggs, larvae and juveniles of migration between river and lake will be investigated for obtaining the information of migratory characteristics and the age and feeding status of juveniles also will be studied. Furthermore, the influence of environmental factors (such as hydrological factors) will be analyzed. Finally, the migration pattern of eggs, larvae and juveniles between the middle reaches of the Yangtze River and Dongting Lake system will be clarified. The results of this research not only contribute to the protection and management of fishery resources, but also enrich the knowledge of fish migration in river floodplain systems.

洞庭湖是我国仅存的两大通江湖泊之一，对江湖洄游鱼类的肥育等方面有着重要意义。近些年，受水利工程等人类活动干扰，长江中游及洞庭湖水系的自然流水体制发生了显著改变，不可避免地影响着江湖洄游鱼类的生活史过程；拟议中的松滋口闸坝工程使得研究该地区鱼类的洄游格局变得更迫切、必要。然而国内相关的研究工作尚未深入开展。本项目选取长江中游-洞庭湖水系中关键的鱼类洄游通道（松滋河、城陵矶水道和湘江下游江段），调查鱼卵、仔鱼入湖、出湖的昼夜变化和季节动态，掌握鱼卵、仔鱼的漂流（被动洄游）过程；研究各通道中入湖方向和出湖方向幼鱼的昼夜变化和季节动态、幼鱼日龄及摄食状况，阐明幼鱼的洄游格局；分析水文因子、饵料生物等环境因子对鱼卵、仔幼鱼洄游格局的影响；以期揭示长江中游-洞庭湖水系鱼卵、仔幼鱼的洄游格局。研究结果不仅有助于保护管理该区域的渔业资源，也能充实河流泛滥平原生态系统中鱼类洄游相关的理论。

长江中游干支流与洞庭湖等附属湖泊组成的江湖复合生态系统孕育了丰富的鱼类资源，研究鱼类在江湖间的洄游格局对维护洄游通道连通性、保护恢复渔业资源具有重要意义。本基金（1）采用分子生物学和形态学相结合鉴定种类的方法，调查分析了长江中游-洞庭湖水系重要洄游通道中鱼卵和仔鱼的漂流过程，松滋河口、湘江下游和洞庭湖通江水道中鱼卵和仔鱼均在5-9月期间顺水漂流进入洞庭湖或长江，并均在6月份达到峰值（值分别为2505.0、121.4和848.8 Ind./1000m3），主要种类为贝氏䱗（Hemiculter bleekeri）、䱗（Hemiculter leucisculus）、鲢（Hypophthalmichthys molitrix）等；各通道中均以江湖洄游性鱼类种类数最多。（2）引入了鱼类运动指数来定量分析洄游型鱼类的运动趋势，阐述了长江中游-洞庭湖水系幼成鱼的洄游格局，松滋河口、湘江下游和洞庭湖通江水道中江湖洄游型鱼类幼成鱼均在4（或5）月份至7（或8）月份有进入洞庭湖的趋势（运动指数分别为0.02~0.7、0.05~0.7和0.04~0.33），8（或9）月份到次年3（或4）月份有出湖入江的趋势（运动指数分别为-0.6~-0.004、-0.7~-0.01和-0.44~-0.07）。（3）使用相关系分析和约束型排序分析方法研究了影响鱼类洄游的环境因子，确定了径流、水位和水温是驱动松滋河口、洞庭湖通江水道江湖洄游型鱼类洄游的因子，水温是驱动湘江下游江湖洄游型鱼类洄游的因子。研究成果可为洞庭湖渔业资源的管理提供科学依据，并可为长江中下游众多闸控湖泊的闸坝运行方案提供指导。