Study On Fish Swimming Performance In Velocity Barrier Of Fishway

The fish passage facilities is an important means of restoring river connectivity,and fishway is becoming China’s main fish pass structure.Studying the fish swimming ability is one of the key factors that make fish successfully pass the fishway flow barrier.For a long time,the fish swimming ability data in the fishway design is seriously insufficient,which has led to the effectiveness of fishway has not been very good.In the previous study,the fish swimming ability test fish species were mainly in the middle and lower reaches of the Yangtze River,such as Mylopharyngodon piceus,Ctenopharyngodon idellus,Hypophthalmictuthys molitrix,Aristichthys nobilis,etc.These fish have only tested critical swimming ability,and there are few other indicators that will be used in fishway design..For example,the induction speed,burst swimming Speed,sustained swimming speed,prolonged swimming speed.So these data are not well used to protect schizothoracids.In this paper,five typical migratory fish(S.irregularis,S.dolichonema,S.prenanti,S.oconnori and S.Younghusbandi)and the middle reaches of the Yangtze River(Opsariichthys bidens)were studied.Traditional classic fish swimming ability test and endurance test in Loligo Systems swim test tank.Opsariichthys bidens tested in the open channel,where the water flow is more natural than swimming tunnels.Through the analysis of the test results,the swimming strategy of Opsariichthys bidens under uniform flow conditions was obtained.The traditional pipeline uniform flow test results were correlated with the open channel test results,and the fishway flow rate design optimization ideas were analyzed.In addition,the fish swimming ability of the six migratory fishes studied in this paper were classified and statistic,and a new idea for fish swimming ability big data statistics was proposed.The main conclusions of this paper are as follows:(1)The swimming tunnels results show that the fish induction speed tested in this paper is basically less than 0.2m/s;the critical swimming speed is:117.61±12.34cm/s(S.irregularis)、81.41±19.74cm/s(S.dolichonema)、73.45±24.13cm/s(S.prenanti)、100.96±21.40cm/s(S.oconnori)、110.75±12.05cm/s(S.Younghusbandi)、95.60±13.77cm/s(Opsariichthys bidens);the burst swimming speed is:210.24±39.56cm/s(S.irregularis)、149.24±25.58cm/s(S.dolichonema)、116.75±38.89cm/s(S.prenanti)、197.23±22.44cm/s(S.oconnori)、113.23±16.68cm/s(Opsariichthys bidens).(2)The endurance test results showed that only a few fish swimming time in10min～200min.The max sustained swimming speed of S.irregularis,S.dolichonema,S.Younghusbandi,Opsariichthys bidens is 0.86m/s,0.6m/s,0.91m/s,0.5m/s;The prolonged swimming speed of S.irregularis,S.dolichonema,S.Younghusbandi,Opsariichthys bidens is 0.86m/s～1.3m/s,0.6m/s～1.7m/s,0.91m/s～1.84m/s,0.5m/s～1.41m/s.In the results of the swim chamber,when the length of the flow velocity obstacle is 50m,the maximum average water flow rates that S.irregularis,S.dolichonema,S.Younghusbandi,and Opsariichthys bidens can pass are:0.98m/s,1.07m/s,1.28m/s,0.86m/s.(3)By analyzing the open channel results of Opsariichthys bidens,it was found that the barley fish upflow velocity barrier started from 75.90cm/s to 89.98cm/s;Opsariichthys bidens absolute swimming speed(sum of swimming speed to flow velocity)and background velocity A linear positive correlation is presented,the speed of swimming to the ground is also linearly positively correlated with the background velocity;In the maximum swimming distance prediction of Opsariichthys bidens,when the water velocity is less than 12.69BL/s,Opsariichthys bidens uses the endurance distance model to obtain the maximum distance..When the water velocity is greater than 12.69BL/s,Opsariichthys bidens uses the burst distance model to obtain the maximum swimming distance.In the flow optimization of fishway analysis,Opsariichthys bidens can be traced back to 290cm when the vertical slot fishway design flow rate is Opsariichthys bidens’critical swimming speed(95.6cm/s),when the vertical slot fishway design flow rate is Opsariichthys bidens’s burst swimming speed(113.23 cm/s)Opsariichthys bidens up to 191cm.At this time,when the vertical seam design flow rate is critical swimming speed or burst swimming speed,the distance that Opsariichthys bidens can trace back is much larger than the vertical slit width of 30 cm.Therefore,there is a certain optimization space for the current vertical slot fishway design flow rate in the case of Opsariichthys bidens.(4)Through the statistical analysis of the fish induction speed,critical swimming speed,burst swimming speed and endurance test results tested in this paper,the small-scale database trend line of each index is obtained,and the induction speed small-scale database trend line is y=0.0061x+0.0405(P<0.05,R~2=0.31).Critical swimming speed small-scale database trend line is y=0.0077x+0.856(P<0.05,R~2=0.66).Burst swimming speed small-scale database trend line is y=0.0667x+0.5771(P<0.05,R~2=0.56).Endurance test small-scale database trend line is lg(y)=-0.1003lg(x)+0.3273(P<0.05,R~2=0.47).