基于鱼道原型观测和水槽试验的鱼类游泳行为研究

Improving the efficiency of fishway is largely dependent on the knowledge of fish swimming behaviors, and thus fish behavior response to micro-hydrodynamic is widely concerned by domestic and foreign scholars. In China, there are still problems for fishway design, such as the scarcity of field monitoring for fish behavior description, and flume tests parameter for fish swimming performence quantification, etc. Herein, this project aims to monitor three-dimensional swimming tracks and the corresponding flow pattern in the vertical slot fishway, and thus to achieve coordinate unification of swimming tracks and flow pattern. Furthermore, by observing the fish micro-behaviors in response to the micro- hydrodynamic in the flume tests, their swimming domain could be determined, while the features of fish swimming in flume tests could be summarized, such as the cases when the tail amplitude and metabolic rate change sharply, as well as the case of critical swimming speed. By comparing the hydraulic factors of swimming domain at the features range in flume and the swimming track domain in fishway, hydrodynamic factors that attract on fish will be analyzed. Finally, the environmental habitat and hydrodynamic variation will be taken into account to explain the strategy of fish migratory pass fishway. Overall, we believe such study will provide theoretical supports for improving fishway designing technology and optimizing test programs.

鱼道运行效果的提升很大程度上依赖于对鱼类游泳行为的明确认识，开展鱼类微行为对微流场的响应研究是国内外学者普遍关注的科学问题。目前，我国鱼道建设面临着定量鱼类行为响应的原型观测资料匮乏、水槽试验测试指标单一等问题。本项目拟通过观测鱼类在安谷竖缝式鱼道中的三维游动轨迹和流场形态，实现鱼类路径、流场的坐标统一；通过观测鱼类在试验水槽中的微行为对微流场的响应特征，确定游动感知域范围，解析鱼游姿态、代谢率发生明显变化及临界游泳速度等特征节点及特征区间；进一步通过感知域关联，对比分析鱼道的游动域、规避域水力因子和水槽试验特征区间的感知域水力因子，判别特征节点的有效性，论证鱼类对流速、紊动因子的权衡和妥协关系，从量测尺度和鱼类生理生态习性方面综合解析鱼类游泳行为的定向机制，总结游动策略。项目成果将为鱼道设计技术提升和试验方案优化提供理论支持。

对鱼类游泳行为的明确认识是鱼道设计的基础，目前我国大部分鱼道以鱼类游泳能力水槽的测试结果作为技术支撑。但游泳能力测试水槽实验因其测试段有压、游动空间有限等原因被认为同鱼类在天然水域中的自主游泳行为存在显著差异。为此，本项目同步开展了鱼类在鱼道中的游泳上溯路径观测；鱼类在游泳能力测试水槽中的游泳速度，及其尾涡涡量、耗氧量和耗氧率、鱼类游泳姿态变化等微行为的定量分析，综合总结了鱼类的游泳速度对应的特征参数变化、水力响应指标等，为鱼道设计提供了一定的技术参考。主要研究成果如下：.（1）在安谷鱼道中追踪标记鱼的上溯路径结果表明：鱼类上溯的主要停留位置为鱼道入口、两个转弯池室处，而在出口位置停留时间最短。鱼类活动行为的峰值主要发生在凌晨和傍晚。结合观测工况的水力学数值模拟，鱼道普通池室的流向明显，鱼类可连续上溯。但在转弯池室，尤其是出口水位398.41m的工况，流向指向不明显，这可能是鱼类在此区域滞留的原因。.（2）鱼类游泳能力测试水槽中的行为观测结果表明：在温度22.0~24.0℃的条件下，体长24.73±0.25cm的鲫鱼以0.15m/s~Ucrit的游泳速度游动时，在平面上鱼尾处会形成一对强度相近方向相反的尾涡，涡强度与游泳速度呈线性关系。实验鱼的尾摆频率、运动步长与游泳速度呈显著线性相关关系，尾摆幅度、头摆幅度随游泳速度呈先增大后减小的变化趋势。.（3）实验鱼通过波状摆动推进，波状运动时尾部会产生涡流场和射流，鱼类可以利用自然界中的涡节省能量；但当水流过于紊乱、或多方向旋涡掺混碰撞，会导致鱼类无法辨别上溯路线，如安谷鱼道转弯池室。为此，在实际工程应用中需根据流场情况在转弯池室设置导流板、导流墩等结构，引导鱼类顺利上溯；在鱼道普通池室设计中，池室流态也应尽量避免出现与鱼体尺寸相近的旋涡。