鲤科鱼类的流速选择及其与食性的关系

The preferred water velocity behavior of six Cyprinids with different feeding habits

为研究食性对鲤科鱼类流速选择行为的影响,本实验选择滤食性的鲢和鳙、草食性的草鱼和中华倒刺鲃、以及杂食性的鲫和锦鲫作为实验对象。在（25±1）℃下将单尾实验鱼置于梯度流速选择仪（流速范围为11.86~65.45 cm/s,等距离划分为5个流速区域）中拍摄1 h,采用Ethovision XT19软件分析视频资料并计算6种实验鱼在不同流速区域平均停留时间（Pt,%）、平均进入频次（F,次/h）和单次进入停留时间（T,s）等流速选择行为指标。结果显示：（1）6种实验鱼的流速选择行为均呈现出2种流速偏好趋势,一类表现为偏好缓流（或静水）（最低流速区域的Pt〉50%）,被定义为Ⅰ型;另一类个体Pt随水流速度的变化出现不同程度的波动,最大Pt通常出现在某一中等流速区,则定义为Ⅱ型;（2）食性对鱼类流速偏好行为有显著影响,Ⅰ型个体中滤食性鱼类对静水或缓流偏好显著大于其他两种食性的鱼类,其中鳙和鲢的Ⅰ型个体在最低端流速区域P_t大于92%;滤食性鲢和鳙的Ⅱ型个体偏好流速高于杂食性的鲫和锦鲫。草食性的草鱼和中华倒刺鲃Ⅱ型流速偏好均不明显,但其在中间流速区域F值最大。研究表明：6种鲤科鱼类的流速偏好行为存在Ⅰ型和Ⅱ型的表型分化并且差异明显,实验鱼的流速偏好行为与食性有关。

The aims of present study were to investigate the effects of feeding habits on preferred water velocity behavior of the cyprinidae fish,six species of cyprinidae fish that have different feed preferences were used as the research subject. To achieve our goals, six cyprinids include silver carp（ Hypophthalmichthys molitrix） and bighead（ Aristichthys nobilis） that are the filter-feeding fish,grass carp（ Ctenopharynodon idella） and qingbo（ Spinibarbus sinensis） that are the vegetarian,and the crucian carp（ Carassius auratus） and goldfish（ C. auratus） that are the omnivorous fish. Firstly,each of six fish species were videoed individually（ N = 12 for each species） in a self-made preferred water velocity determining device,i. e.,a 1. 5 meters long conical raceway with water speed gradually increasing from 11. 86 to 65. 45 cm / s at（ 25 ± 1. 0） ℃. The videos were then analyzed by Ethovision XT19 and the percent time stayed（ Pt）,frequency（ F） and the average duration of each fish stayed（ T） in each water velocity interval were all calculated. Our results showed that（ 1） the preferred water velocity behavior of the six fish species are presented into two kinds of trends. If an individual of a given species stayed mainly in the lowest water velocity interval（ Pt 50%）,the fish individual is considered Type Ⅰ. Otherwise,the fish is considered Type Ⅱ. At the same time,the experimental results indicated that feeding habit has a significant effect on the water velocity preference behavior of the experimental fish. Compared to the Type I of omnivorous habit fish including the crucian carp and goldfish and herbivorous fishes including grass carp and qingbo,the Type Ⅰof filter-feeding fish including the silver carps and bighead showed more significant preference of the lowest water velocity interval. The Type Ⅱ of filter-feeding fish preferred stay in higher water velocity than the omnivorous habit fish. However,the Type Ⅱ of herbivorous fishes including the grass carp and qingbo showed no preference to the water velocity intervals,but it had higher F values in middle water velocity intervals. The present study suggested there is a sharp variation in the water velocity preference behavior of six experimental fish species. This water velocity preference behavior for each species could be divided into Type Ⅰ and Type Ⅱ. In addition,feeding habit has a significant effect on the water velocity preference behavior of the experimental fish.