INFLUENCE OF SIDEWALL ON SWIMMING BEHAVIOR OF ISOLATED AYU, PLECOGLOSSUS ALTIVELIS ALTIVELIS

Abstract

To investigate the swimming behavior of juvenile Megalobrama amblycephala, a tracking analysis device was designed to monitor behavior indicators including velocity (V), swimming distance (SD), turn angle (TA), distance to center-point (DC) and swimming track (ST) at different flow rates (0, 0.1, 0.2, 0.3 and 0.4 m/s) at 25℃. Results showed that indicator values all increased with increasing flow rate. Values of V, SD and TA showed no significant differences among the flow rates of 0, 0.1 and 0.2 m/s, respectively (P>0.05). However, they increased obviously at flow rates of 0.3 and 0.4 m/s (P<0.05), with no significant differences found between these two flow rates (P>0.05). The SD value did not change markedly according to flow rates (P>0.05), while ST showed complex patterns corresponding to increasing flow rate. A significant linear positive correlation occurred in free-swimming fish between V and SD, while a negative relationship was found between V and TA. No regular relationship was deduced between swimming speed and DC. 为探讨团头鲂幼鱼(Megalobrama amblycephala)游泳行为对水流的响应规律, 该文通过特制鱼类游泳行为测定装置, 测定了团头鲂幼鱼在25℃, 0、0.1、0.2、0.3、0.4 m/s流速条件下的游速、游距、转角、至中心点的距离及游泳轨迹。结果表明:随着流速的增大, 个体游速、游距及转角值均相应增大。0、0.1及0.2 m/s流速组间的游速、游距及转角差异均不显著(P>0.05), 但显著小于0.3和0.4 m/s组别, 且0.3和0.4 m/s流速组之间差异均不显著(P>0.05);整个时间段内, 个体至中心点的距离随流速增大并未呈现明显规律性, 各流速间差异不显著(P>0.05), 游速与游距呈显著线性正相关, 而与转角呈显著线性负相关, 与至中心点的距离则无相关性;游泳轨迹随水流增大趋向复杂化。