中文摘要：

为考查测定临界游泳速度（Ucrit）方案中的持续时间（Δt）对南方鲇（SilurusmeridionalisChen）幼鱼的Ucrit及其代谢率的影响,于25℃条件下以6.0cm·s^-1为速度增量（Δv）,分别在Δt为20和40min时测定实验鱼的Ucrit和运动代谢率（VO2）。结果显示在Δt为20和40min时实验鱼的绝对临界游泳速度（Ua）分别为（31.89±1.29）和（30.17±0.98）cm·s^-1,相对临界游泳速度（Ur）分别为（4.22±0.16）和（4.05±0.14）BL·s^-1（BL表示实验鱼的体长,以厘米计）,两个临界游泳指标不同处理间均无显著差异;而Δt为20min时的最大运动代谢率（AMR）为（183.36±12.80）mg·h^-1·kg^-1,显著高于Δt为40min下（139.66±8.75）mg·h^-1·kg^-1的水平（p〈0.05）;另外,当Δt为40min时,前20min和后20min的AMR分别为（152.08±10.79）和（121.61±6.68）mg·h^-1·kg^-1,前者显著高于后者（p〈0.05）,却显著低于Δt为20min处理组的水平（p〈0.05）。上述结果表明,不同的持续时间对南方鲇幼鱼的Ucrit的测定结果无明显影响;而对AMR存在着显著性的影响,这种影响可能与实验鱼的应激反应程度有关,也可能由于运动过程中无氧代谢的不同比例所致。

英文摘要：

To investigate the effects of test duration（△t） on the values of the critical swimming speed （Uerit）and metabolic rate in juvenile southern catfish （Silurus meridionalis ）, the Ucrit, and swimming metabolic rate （Vo2） with the velocity increment （Av） 6.0 cm · s^-1 at water 25 ℃ were measured using two different duration （20,40 min）. The results revealed that： when the duration was 20 and 40 min, the absolutely critical swimming speed （ Ua）was （31.89 ± 1.29） and （30.17 ±0.98） cm · s^-1 while the relative critical swimming speed （Ur）was （4.22 ±0.16） and （4.05 ±0.14）BL · s^-1 respectively. Experimental treatment had no significant effect on the values of critical swimming speed ; but the maximum swimming metabolic rate of 20 rain duration was （ 183.36 ± 12.80） nag · h^-1 · kg ^-1, which was significantly higher than that of 40rain duration group （ （ 139.66 ± 8.75 ） mg · h^-1 · kg ^-1 ）. Furthermore, for fish in the 40 min duration group,the AMR calculated as the first 20 rain and the latter 20 min were （ 152.08 ± 10.79） and （ 121.61±6. 68） mg · h^-1 · kg^-1 respectively. The former value was siguificantly higher than that of the latter （p 〈0.05）, but both were marked lower than that of 20 min duration group （p 〈 0.05 ）. The results showed that： test duration had no significant effect as for the measure value of critical swimming speed in juvenile southern catfish while it had remarkable effect on the maximum swimming metabolic rate. The effect may relate to the stress response to increased water speed or due to different anaerobic metabolism ratio during swimming.