人工繁殖圆口铜鱼幼鱼游泳能力与游泳行为研究

利用鱼类游泳能力测定装置,以人工繁殖的圆口铜鱼(Coreius guichenoti)幼鱼为实验对象,体重(3.05±0.99)g,体长(5.94±0.66)cm,采用递增流速法研究其游泳能力与游泳行为。结果表明,在(20±1)℃水温条件下,圆口铜鱼平均相对临界游泳速度(critical swimming speed,U_crit)为(8.41±1.56)BL/s;其步态转换速度(gait transition speed,U_chg)与临界游泳速度呈线性正相关:U_chg=0.63 U_crit+0.21(P<0.01,R 2=0.86);摆尾频率(tail beat frequency,TBF)与进口流速(inlet velocity,U_in)呈线性正相关:TBF=0.48 U_in+2.53(P<0.01,R 2=0.95);进口流速(inlet velocity,U_in)与步长(step length,SL)呈线性正相关:SL=0.11 U_in+0.41(P<0.01,R 2=0.99)。实验鱼的摆尾幅度(tail beat amplitude,TBA)、冲刺次数、各进口流速下的摆尾时间百分比及稳定摆尾与非稳定摆尾比例,均随进口流速改变而变化。随流速增大,摆尾幅度呈现先增大、再减小、最后又增大的趋势;冲刺次数也是先增加、随后逐渐下降;摆尾时间百分比最初是快速增大,随后基本保持不变,流速增至8 BL/s高流速时,再次随流速增加而快速增大。当流速与临界游速比值(U/U max)为0.38时,实验鱼出现非稳定摆尾行为;比值为0.58时,实验鱼稳定摆尾行为与非稳定摆尾行为比例为1∶1;比值增至0.78时,稳定摆尾行为消失。人工繁殖的圆口铜鱼游泳能力较强,在不同流速下,通过改变游泳行为以保持更长的游泳时间及距离。研究结果可为以圆口铜鱼为过鱼对象的鱼道建设以及养殖流速优化提供参考。

Swimming Ability and Behavior of Artificially Propagated Largemouth Bronze Gudgeon(Coreius guichenoti)

Largemouth bronze gudgeon (Coreius guichenoti), a typical anadromous fish, is an important economic fish species once commonly found in Yangtze River, but populations have been rapidly declining in recent years. One of the important factors is the interruption of the natural connection of the rivers by dams. Swimming is crucial for the survival and reproduction of fish and, in this study, we characterized the swimming ability and behavior of the artificially propagated C. guichenoti using a stepped velocity test. The objectives were to better understand C. guichenoti swimming and provide data for the design of effective fishways. Artificially propagated juvenile C. guichenoti of body weight (3.05±0.99) g and body length (5.94±0.66) cm were tested at (20±1 oC) in a flume-type respirometer equipped with a high speed video camera system to record swimming behavior. The average relative critical swimming speed (Ucrit) was (8.41±1.56) BL/s and the gait transition speed (Uchg) of 0.63 Ucrit was positively correlated with the critical swimming speed, Uchg=0.63Ucrit+0.21 (P<0.01, R2=0.86). The tail beat frequency (TBF) was positively correlated with inlet velocity, (Uin); TBF=0.48Uin+2.53 (P<0.01, R2=0.95), as was step length (SL), SL=0.11Uin+0.41(P<0.01, R2=0.99). Tail beat amplitude (TBA), sprint time, percentage of tail beat time and the ratio of stable tail beat to unstable tail beat all varied with inlet velocity. With increasing flow velocity, the TBA increased first, then decreased and finally increased; the number of sprints increased first and then decreased gradually; the percentage of tail beat time increased rapidly at first, then remained basically unchanged, and increased rapidly again at the flow velocity of 8 BL/s; the unstable tail beat appeared when the ratio of flow velocity to critical swimming velocity (U/Umax) was 0.38. The ratio of stable tail-beat to unstable tail-beat was 1:1, when U/Umax was 0.58. When the ratio (U/Umax) increased to 0.78, the stable tail-beat behavior disappeared, and the swimming behaviour was mainly sprint. In general, the swimming ability of the propagated largemouth bronze gudgeon was stronger than that of the wild ones, and the swimming behavior was significantly correlated with flow velocities. C. guichenoti can alter swimming behavior in order to swim longer and farther at different flow velocities. The results can provide reference for the fishway construction of largemouth bronze gudgeon and the optimization of aquaculture velocity.