鲢幼鱼非疲劳贴网及姿态转换行为研究

流速是影响鱼类生存与繁衍栖息的重要因子。为了了解鱼类在中等流速区的游泳行为,探究其对水流的适应特征,利用鱼类游泳能力测定装置,以鲢(Hypophthalmichthys molitrix)幼鱼体重(9.82±3.81) g,体长(8.56±1.11) cm)]为对象,采用递增流速法,分析了游泳过程中的非疲劳贴网行为与姿态转换行为。结果表明,在22℃水温条件下,鲢幼鱼平均相对临界游泳速度(critical swimming speed,U_(crit))相比其体长(body length,BL)为(6.00±0.93)BL/s;其非疲劳贴网速度(no-fatigue impingement speed,U_(imp))与临界游泳速度呈线性正相关,U_(crit)=1.03 U_(imp)+1.26 (R~2=0.86,P0.01);姿态转换速度(gait transition speed,U_(tran))与临界游泳速度呈线性正相关,U_(tran)=0.59 U_(crit)+1.55 (R~2=0.43,P0.01);非疲劳贴网速度与姿态转换速度呈线性正相关,U_(tran)=0.51U_(imp)+2.72 (R~2=0.41,P0.001)。在中等流速范围内(2～4 BL/s),实验鱼摆尾频率(tail beat frequency, TBF)和单次摆尾周期前进距离(stride length, SL)均随流速增加而增大。首次出现非疲劳贴网的流速为4.62 BL/s,流速增至5.08 BL/s时出现姿态转换行为。发生姿态转换后,TBF开始下降,而SL随流速增加快速增大。研究显示,鲢幼鱼非疲劳贴网行为对游泳能力和姿态转换速度有显著影响,且非疲劳贴网行为与姿态转换行为之间也存在相互影响。研究结果可为自然环境中鱼类生态行为研究、鱼类资源保护及渔业管理提供参考。

Research on Non-Fatigue Impingement and Gait Transition Behavior of Juvenile Silver Carp (Hypophthalmichthys molitrix)

Water flow profoundly affects fish swimming behavior. Changes in flow velocity stimulate the sensory organs of fish, affecting activity mode and stimulating complex reaction mechanisms. In this study, we investigated the swimming behavior of juvenile silver carp (Hypophthalmichthys molitrix) in the medium velocity range and studied adaptations to changes in water velocity. Juvenile silver carp body weight (9.82 ± 3.81) g, body length (BL, 8.56 ± 1.11) cm)] were acclimated for a week before testing. Non-fatigue impingement, tail beat and gait transition of the test fish, and their relationship to critical swimming speed (Ucrit), were investigated in a swim chamber at 22 °C using the stepped velocity test. The average relative critical swimming speed (Ucrit) was 6.00±0.93 BL/s and the non-fatigue impingement speed (Uimp) and gait transition speed (Utran) were both positively correlated with the critical swimming speed; Ucrit = 1.03 Uimp + 1.26 (R2 = 0.86, P<0.01), Utran = 0.59 Ucrit + 1.55 (R2 = 0.43, P<0.01). The non-fatigue impingement speed was also positively correlated with gait transition speed, Utran = 0.51Uimp + 2.72 (R2 = 0.41, P<0.001). In the medium velocity range (2-4 BL/s), both tail beat frequency (TBF) and stride length (SL) increased with water velocity. Non-fatigue impingement was first observed at 4.62 BL/s and the gait transition occurred at 5.08 BL/s. After the energy conserving gait transition, TBF decreased slightly with increasing flow velocity as SL increased. Our results show that non-fatigue impingement significantly affects swimming behavior and gait transition speed, and there is an interaction between non-fatigue impingement and gait transition. Non-fatigue impingement increases energy consumption and the higher the velocity at impingement, the higher the gait transition velocity. This research provides a reference for behavioral aspects of fish ecology to support fish resource conservation and fishery management.