Swimming Performance Of Four Juvenile Fishes In Acipenseridae

Overmuch hydroelectric development breaks continuity of rivers so that migrationways of sturgeons are obstructed, which leads that propagation is influenced significantly.Currently, a great of dams is built in many rivers and China also develops hydraulicengineering rapidly. Researchers advocate build fishways to help fish to migration. Expertsin hydraulics filed design fishways many years ago. However researchers find that fishbiology information is very important to fishways. Study of fish swimming performance isrequisite to design fishways.Expecting for water temperature and flow velocity, fatigue and feeding/digestion arealso important factors to fish swimming performance. But the reports about two factors arelimited. In this study, swimming performance of Acipenser schrenckii, Acipenser sinensis,Acipenser baerii and Acipenser ruthenus were investigated. The difference among themwere analyzed. The effect of flow speed, fatigue and feeding/digestion on swimmingperformance are revealed. Main works and results are as follows:1. In the four sturgeons, Acipenser schrenckii had low swimming capability butAcipenser sinensis had high swimming capability. Acipenser ruthenus had low swimmingefficiency but Acipenser baerii had high swimming efficiency. Acipenser sinensis had lowcapability of anaerobic respiration but Acipenser baerii had high capability of anaerobicrespiration. Acipenser sinensis recover fast after fatigue but Acipenser baerii recoverslowly after fatigue. Main resources of fish are carps in China. Sturgeons had lowswimming capability compared with carps. However, sturgeons had high swimmingefficiency, which cater to long-distance migration.2. The counter-current swimming capability of Acipenser schrenckii was low withcritical swimming speed of1.96±0.10bl/s at20oC. When a linear function was fitted to thedata, oxygen consumption, as a function of swimming speed, was determined to beMO2=337.29+128.10U (R2=0.971, P<0.001) and the power value (1.0) of U indicated highswimming efficiency. Excess post-exercise oxygen cost was48.44mgO2/kg and indicatedexcellent fatigue recovery. Cost of transport decreased slowly with increased swimmingspeed.3. Critical swimming speed of Acipenser sinensis decreased from4.34bl/s to2.98bl/swith four repeated step tests; active oxygen consumption decreased from1175mgO2/kg to341mgO2/kg and was the primary reason for the decrease in Ucrit; excess post-exercise oxygen consumption decreased from36mgO2/kg to22mgO2/kg; with repeated step tests,white muscle (anaerobic metabolism) began contributing to propulsion at lower swimmingspeeds; Acipenser sinensis conserve energy by swimming efficiently and have high fatiguerecovery capability.4. Critical swimming speed of Acipenser baerii was3.26±0.11bl/s under normalcondition. However, the Ucritdecreased rapidly because of excess post-exercise. It wasnoted that the Ucritthen recovered to78percent of its initial strength in1hour of rest timeand then recovered completely in little more than1day. Change in the maximum oxygenconsumption rate was also similar to that of the Ucrit. The speed exponent in oxygenconsumption functions was close to1. In addition, excess post-exercise made swimmingefficiency decrease. Besides, there was a durative effect of excess post-exercise onswimming efficiency, which lasts for at least1week. Excess post-exercise restrainedanaerobic respiration. The effect of excess post-exercise on excess post-exercise oxygenconsumption was stronger when the sturgeon was left to rest for less than1day comparedto that when the rest time was1week.5. Critical swimming speed of Acipenser ruthenus increases a little and thendecreased with fasting time. The fasting time which is less than2days affect swimmingcapability little. But swimming capability decreases significantly when the fasting time ismore than1week. The fasting time which is less than1week affect swimming efficiencylittle. But swimming efficiency is affected significantly when the fasting time is more than2week. Capability of anaerobic respiration is low when much food is not digested in thesturgeon body and when strong starvation is felt by the sturgeon. However, capability ofanaerobic respiration is high when much food is just digested.