四大家鱼幼鱼下行行为及流场偏好研究

Swimming Behaviours and Flow Field Preferences of the Four Major Chinese Carps During Downstream Migration

探究典型江河半洄游性鱼类的摄食、育肥等下行洄游需求,可为鱼类下行通道的设计与评价提供技术支撑。以全长5~13 cm四大家鱼(青鱼、草鱼、鲢、鳙)幼鱼为研究对象,通过构建模型实验,在进口流速为0.2 m/s时,分析同一水流环境下鱼类的运动行为,开展其下行过程中应用水力条件的行为响应及流场偏好研究。结果表明:(1)青鱼、草鱼、鲢、鳙幼鱼的下行成功率分别为58.3%、78.6%、74.5%、87.2%,下行轨迹主要集中在主流区域;(2)四大家鱼幼鱼多表现为主动下行行为,鳙幼鱼的直接下行率最高(88.5%),青鱼、鲢幼鱼分别为60.0%、56.2%,草鱼幼鱼发生延迟下行的概率(56.3%)大于直接下行率(43.8%);(3)实验鱼对不同流速范围的选择存在差异性,四大家鱼幼鱼在同一水力环境条件下的下行行为选择存在一定的规律性,青鱼、草鱼、鲢、鳙幼鱼的共同偏好流速为0.228~0.454 m/s,共同偏好紊动能为0.0014~0.0023 m^(2)/s^(2)。

The four major Chinese carps,the black carp(Mylopharyngodon piceus),grass carp(Ctenopharyngodon idella),silver carp(Hypophthalmichthys molitrix)and bighead carp(Aristichthys nobilis)are semi-migratory fish,and their juveniles migrate downstream for feeding and weight gain.In this study,juveniles of the four major Chinese carps of body length 5-13 cm were selected for research,and we explored the effects of flow velocity and turbulent kinetic energy on downstream migration and described the behavioral responses and flow field preferences of the four species during downstream migration.Our aim was to provide technical support for the design and evaluation of downstream fish passages.A model experiment was conducted in an open flume with barriers to form typical flow fields,and the movement behavior of the test fish was recorded at an inlet flow rate of 0.2 m/s.Results show that:(1)The success rates of downstream migration for juvenile black carp,grass carp,silver carp,and bighead carp were 58.3%,78.6%,74.5%,and 87.2%,respectively,and their downstream trajectories were mainly concentrated in the main flow stream.(2)Among fish that successfully passed,most displayed active downstream behavior,and the rate of direct downstream behavior was the highest for bighead carp(88.5%),followed by black carp(60.0%)and silver carp(56.2%).For grass carp,the proportion of non-direct downstream migration(56.3%)was higher than that of direct downstream migration(43.8%).(3)There were differences in the selection of velocity ranges among the test fish,and there were some regularities in downstream migration behaviors in the same hydraulic environment.Among the four major Chinese carps,their preferred flow velocity range was 0.228-0.454 m/s,and their preferred turbulence kinetic energy range was 0.0014-0.0023 m^(2)/s^(2).