Study on Fish Migration through a Stone-Embedded Fish Passage Based on Preference

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1 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 Study on Fish Migrtion through Stone-Embedded Fish ssge Bsed on reference Rin FEBRINA 1) 2), Mshiko SEKINE 2), Hiroshi KANEMOTO 2), Koichi YAMAMOTO 2), Ariyo KANNO 2), Tky HIGUCHI 2), Tsuyoshi IMAI 3) 1) Deprtment of Civil Engineering, Fculty of Engineering, Mlhyti University, Jl.rmuk No. 27 Kemiling, Bndr Lmpung 35153, Indonesi 2) Division of Civil nd Environmentl Engineering, Grdute School of Science nd Engineering, Ymguchi University, Tokiwdi, Ube, Ymguchi , Jpn 3) Division of Science nd Engineering, Grdute School of Science nd Engineering, Ymguchi University, Tokiwdi, Ube, Ymguchi , Jpn ABSTRACT A stone-embedded fish pssge (SEF) llows fish to pss brrier by reducing the velocity in the slope. The efficiency of SEFs hs however not been evluted well nd the design prmeters re not cler. The efficiency of SEFs for fish therefore needs to be evluted nd nlyzed. In this reserch, we ttempted to develop simple eqution to estimte the pssbility of n SEF for Ayu (lecoglossus ltivelis), which is pplicble in the SEF s designing stge. We reproduced the SEF conditions experimentlly. The set-up consisted of pool nd chnnel, nd evluted its pssbility bsed on physicl conditions such s ir bubbles, velocity, nd depth. With the results, we developed decision tree to explin the pssbility using design vribles such s dischrge, chnnel slope, nd pool size nd depth. Then, to estimte the whole SEF, we proposed n eqution which clculted the verge of the decision tree outputs throughout the SEF s whole scending routes. Lstly, we verified the eqution through field experiments. The eqution showed good greement with the observed fish scent success rte. This technique could therefore be used to evlute SEF in its designing stge. Keywords: decision tree, preference of Ayu, stones-embedded fish pssge INTRODUCTION Upstrem or downstrem fish migrtion tkes plce for purposes such s food nd spwning. Brriers cross rivers often hve negtive impcts on nturl fish popultions nd, long with other fctors, my contribute to the diminished bundnce, disppernce, or even extinction of species. Fish pssges re instlled to minimize the severe impct on the river ecosystem. The effectiveness of fish pssge is closely linked to the wter velocities nd flow ptterns nd its design should tke into ccount the behvior of the trget species. In Jpn, pool nd weir fish pssges commonly provided upstrem routes for Ayu (lecoglossus ltivelis), which is n mphidromous species nd is one of the most importnt commercil fish in Jpn (Ishid, 1976). However, these trditionl fish pssges hve sometimes been degrded becuse of river bed degrdtion or other problems nd mny of them require restortion. Recently, the stone-embedded fish pssge (SEF) is gining populrity in some res of Jpn s n inexpensive smll-scle river restortion method. The Fushino River SEF is such pssge, intended to improve or substitute existing pool nd weir fish pssges. Although the Fushino River SEF hs been widely introduced through book (roject Tem "Mizube no Kowz", 2007) nd hs been highly pprecited, the efficiency of the SEF hs not been Address correspondence to Rin Febrin, Deprtment of Science nd Engineering, Grdute School of Science nd Engineering, Ymguchi University, Emil: r007wc@ymguchi-u.c.jp Received My 23, 2014, Accepted September 19,

2 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 evluted well nd its design prmeters re not yet cler enough. We conducted preliminry survey on the Fushino River SEF in Unlike the expecttion tht stones would be used for roughness, the Fushino River SEF ws network of smll pools nd chnnels under its operting dischrge (Fig. 1). Also, observtion during the survey showed tht ir bubbles, high velocity, nd low chnnel nd pool depths were mjor obstcles for fish scendnce. Existing SEF reserch (Miyzono nd Tomtsu, 2003; Miyzono et. l., 2005; Fujihr nd Chhtkuli, 2006) modeled them s stones on flt bed nd did not tke ir bubbles into ccount. A smll mount of ir bubbles would increse the dissolved oxygen nd crete fvorble conditions for fish. However, lrge mount of ir bubbles would reduce the wter density nd inhibit fish movement. The purpose of this reserch ws to build simple model, pplicble to the SEF design stge, to estimte the pssbility of the SEF for Ayu, using preference informtion on velocity, depth, nd ir bubbles. We then verified the model through field experiments in the Fushino River SEF. Chnnel ool Fig. 1 - Network of smll pools nd chnnels t the Fushino River SEF

3 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 MATERIALS AND METHODS Lbortory experiment The experimentl setup consisted of pool nd chnnel (Fig. 2). A schemtic overview of the experimentl setup is shown in Fig. 2b. It ws mde of trnsprent crylic. In this experiment, the depth of the pool (Do) ws chnged by replcing bottom plte spcers, the length of the chnnel (LoC) by replcing the chnnel prts, nd the slope of the chnnel (SoC) by lifting the upper tnk. Width of the chnnel (WoC) ws fixed t 10 cm. The slope of the flood gte (SoG) ws djusted to mke smooth wter surfce level trnsition in the chnnel nd pool. The experimentl flow rte (Q) ws mesured t the flood gte. Depth of the chnnel (DoC) ws mesured t the center of the chnnel. Velocity of the chnnel (VoC) ws clculted s VoC = Q / (DoC WoC). The conditions of the Fushino River SEF were represented in the lbortory experiments. Tble 1 lists the observed chrcteristics in the SEF nd the experimentl conditions. Velocity nd ir bubbles were mesured in the pool t the points shown in Fig. 3. Velocity of pool (Vo) ws mesured using two propeller type velocity meters (VR-201 or SV-3, KENEK, Tokyo, Jpn), depending on the depth. The bubble condition index (BCI) ws observed where BCI = 0: no ir bubble; 0.1: ir bubbles ppered on the surfce; 0.5: ir bubbles reched the middle of the pool; nd 1: ir bubbles reched the bottom of pool. () (b) Top View ool Flood gte WoC ool Chnnel Unit : mm 200 Upper tnk Chnnel Side view SoG Outflow Fig. 2 - Experimentl setup, with () the pool nd chnnel, nd (b) schemtic top nd side view of the setup. Do SoC Bottom plte Bottom plte spcers

4 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 Tble 1 - ool nd chnnel prmeters in the Fushino River SEF nd the lbortory experiments. ool prmeters Chnnel prmeters Are (Ao) Depth (Do) Length (LoC) Width (WoC) Slope (SoC) Depth (DoC) cm 2 cm cm cm cm/cm cm Minimum Fushino River SEF Averge 1, (265 chnnels Mximum 16, Stndrd & 109 pools) 2, devition Experimentl conditions (All combintions were tested except Ao 2500 DoC 10.0) 625 (25 25) ,500 (50 50) Velocity mesurement Air bubble mesurement () (b) Fig. 3 - Mesuring points for () the cm pool nd (b) the cm pool. Estimtion of pssbility in lbortory experiments We defined set of rules to estimte the pssbility in the lbortory experiment bsed on preference informtion on velocity, ir bubbles, depth, nd spce. We ssumed tht Ayu s body length (BL) ws 6 cm (BL6) nd the body height (BH) ws 1.3 cm, becuse this is common size when they strt upstrem migrtion nd becuse Ayu of this size ws used in some of our previous reserch, which we refer to below. Velocity Nkmur (1995) stted tht fish cn swim t burst speed just for few seconds, while they cn swim for hours t cruising speed. Ayu s burst speed is BL/s nd their cruising speed is 4 7 BL/s. Sekine et l. (2009) used preference model in which Ayu could not swim more thn 4 s t burst speed. With this informtion we defined two rules: time of scending (ToA) < 4 s nd Vo < cruising speed. Time of scending ws clculted using ToA = LoC / (burst speed VoC). Burst speed nd cruising speed were clculted by 15 BL/s nd 5.5 BL/s respectively

5 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 Air bubbles Noguchi et l. (2007) experimentlly estimted preference of Ayu for ir bubbles using scle of 0 (no preference) to 1 (mximum preference). In the reserch, Ayu showed the highest preference of 1 t 0%(v/v) ir nd showed slightly lower preference of 0.75 t 5%(v/v) ir. After tht, preference quickly decresed down to 0.13 t 10%(v/v) ir nd becme lmost zero for 20%(v/v) ir. Wter with 5%(v/v) ir bubbles ws cceptble for fish to sty nd move. We lso lerned through our field observtions tht bubbles tended to sty in the upper lyer of the wter nd tht fish could sty in the bottom lyer when it hd no bubble re. With this informtion we defined rule: BCI 0.1 when Do = 2 cm nd BCI 0.5 when Do = 9, 18 cm. Depth Nkmur (1995) stted tht the minimum wter depth for swimming ws two times BH. However we frequently observed Ayu swimming through shllow wter with their bck emerged in the ir. With this informtion we define rule: Do BH. Spce Nkmur (1995) stted tht minimum rest plce size ws 2 4 BL long nd ½ BL wide. We determined the pssbility of chnnel nd ech cell ( rectngulr re with one velocity mesuring point in pool) bsed on the rules described bove. However, the cell length of the cm pool ws 5 cm long the flow, which ws smller thn Ayu s BL of 6 cm. To determine the pssbility of pool, we defined rule: t lest two connected pssble cells were necessry for the cm pool nd one pssble cell ws necessry for the cm pool. With the rules bove, we estimted the pssbility (I: impssble, : pssble) for ech experimentl condition. Decision tree on pssbility of chnnel nd pool pir We employed the decision tree (Hullet, 2006) s simplified method to estimte the pssbility of chnnel nd pool pir in the SEF designing stge. The explntory vribles were Q, SoC, LoC, Do nd Wo, ll of which could be determined in the designing stge. Using set of these explntory vribles nd the pssbility s dependent vrible obtined through lbortory experiments, we built decision tree using the sttisticl pckge R. Field experiments for decision tree verifiction To verify the model, we pplied the decision tree to the Fushino River SEF. We used three experimentl conditions: experiment 1 used the whole SEF re; experiment 2 used the SEF s centrl zone, which represented the re with few ir bubbles nd low flow rte; nd experiment 3 used the SEF s right bnk, which represented the re with dense ir bubbles nd high flow rte. We relesed 100 (experiments 1 nd 3), or 50 (experiment 2) Ayu downstrem of the fish pssge entrnce nd video recorded the number of Ayu tht successfully pssed through the SEF. Body length of the relesed Ayu ws 7 ± 1 cm, which ws slightly lrger thn the BL of 6 cm tht we ssumed in our pssbility estimtion of the lbortory experiments. We lso conducted n environmentl condition survey on Vo nd VoC using KENEK VR-201, BCI of pools by visul observtion, nd Do nd DoC using ruler

6 ## あ Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 RESULTS AND DISCUSSION Figure 4 shows the results of the pssbility estimtions of the lbortory experiments. The most significnt prmeter ws DoC, which ws strongly relted with Q. When DoC becme deeper, the pssbility ws reduced. Lrger pool size positively ffected the pssbility, becuse it incresed the number of pssble cells. Longer LoC nd steeper slope negtively ffected the pssbility. Figure 5 shows the decision tree on the pssbility of chnnel nd pool pir. The decision tree lso showed tht Q ws the most significnt vrible nd tht Wo, Do, nd SoC followed. lese note tht the vlues in Fig. 5 strongly depended on the experimentl conditions. For exmple, the Wo vlue of 37.5 for the second brnch just distinguished 25 cm from 50 cm Wo. There ws no difference when we estimted the results of the lbortory experiment, even when this vlue ws 25.1 or 49.9 cm. Becuse of this, we only showed the frmework of the SEF estimtion model here. To increse the pplicbility of the decision tree to other SEFs, more lbortory experiments with different condition would be required Slope DoC 1 cm ool 25 x 25 ( *) ool 50 x 50 ( *) LoC 30 cm LoC 15 cm LoC 5 cm LoC 30 cm LoC 15 cm LoC 5 cm Do(cm) Slope Slope 0.5 Slope 1.0 Slope 0.1 Slope 0.5 Slope 1.0 Slope 0.1 Slope 0.5 Slope DoC 10 cm Time to pss through the chnnel (s) <= 1 <= 2 <= 3 <= 4 > 4 VoC > burst speed DoC 4 cm Note: The estimted pssbility in the pool (light blue cell = Ayu cn rest in the cell, white cell = Ayu cnnot rest in the cell); the estimted pssbility of chnnel (red nd blck chnnel = Ayu cnnot pss through the chnnel, other colors = Ayu cn pss through); totl pssbility of the pool nd chnnel (drk blue = good, white = not good). Fig. 4 - ssbility estimtion of the lbortory experiments A C D B E A= Overll pssbility B= Velocity of chnnel(m/s) C= Chnnel pssbility D= Cell pssbility E= Flow rte (cm 2 /s)

7 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 I 9/0 I 18/1 Q < 4,567 31/12 Q > 4,567 Do < 13.5 Q >= 5,198 Q < 5,198 12/4 Q < 5,080 13/11 Do >= 13.5 Q >= 5,080 Q >= 3,233 Q < 3,233 1/7 I 3/4 3/1 0/3 Impssble = I = ssble Impssble cse number in the experiments / ssble cse number in the experiments 41/94 I 7/1 I 2/1 Q < 1,445 Q >= 810 Q < /14 Q >= 1,445 SoC >= 0.3 Q >= 2,341 Q < 2,341 Wo < 37.5 Wo >= 37.5 SoC < 0.3 Fig. 5 - Decision tree on overll pssbility of chnnel nd pool pir. 2/6 10/33 2/6 0/5 10/82 0/19 0/8 0/49 Figure 6 shows the set-up of the field experiments. The experiments were conducted on the 12th (experiment 1), 14th (experiment 2), nd 15th (experiment 3) of My nd the 8th of June (environmentl condition), The flow rtes entering the SEF were m 3 /s, m 3 /s, m 3 /s, nd m 3 /s on these dtes, respectively. Wter temperture ws pproximtely 17 C for ll experiments. During the environmentl condition survey, prmeter vlues were mesured t bout one fourth of ll pools nd chnnels to cover s wide rnge of prmeter vlues s possible. For un-mesured pools nd chnnels, prmeter vlues were estimted using result of nother survey, which hd been conducted for ll pools nd chnnels on 28th Jnury 2011 under flow rte of m 3 /s. The 2013 vlues of the trget pool/chnnel were clculted bsed on the verge rtio of the 2011 nd 2013 vlues of the similr pools/chnnels which hd both 2011 nd 2013 vlues. Figure 7 shows the environmentl conditions t the SEF. Tble 2 shows the number of successfully scended Ayu. Interestingly, even if the fish scending routes in experiment 1 included ll scending routes in experiment 2, the scent success rte of experiment 1 within 30 minutes ws much smller thn tht of experiment 2. This might be becuse the fish could not estimte the whole route s pssbility nd hd chnce to enter n impssble route even when pssble route existed

8 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 Experiment 1 Experiment 2 Experiment 3 Boundry ool Slope Boundry ool Slope Fig. 6 - Experimentl re. Boundry ool Slope Velocity [m/s] Wter depth [m] Bubble condition () (b) (c) Fig. 7 - Environmentl conditions t the Fushino River SEF, with () velocity (b) wter depth, nd (c) bubble condition. Tble 2 - Number of successfully scended Ayu. Number Number of Number of of scended Ayu scended Ayu relesed within 30 minutes Ayu Investigtion time [h] Ascent success rte within 30 minutes [%] Experiment Experiment Experiment

9 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 We evluted the Fushino River SEF using the decision tree nd bsed on the environmentl conditions (Fig. 8). To estimte Q for ech chnnel, the flow rte entering the upper pool ws distributed to ech downstrem chnnel bsed on their dischrge section re. Then, the estimted results of the decision tree (= Ep, which is 0 when impssble or 1 when pssble) were given to ech chnnel, not to ech chnnel nd pool pir. This ws becuse some pools were pired with multiple chnnels nd such pirs, shring the sme pool, sometimes showed different results. In Fig. 8 ll scending routes hd more thn one impssble chnnel nd pool pir. This ws even true for experiment 2, in which more thn 50% fish hd scended. This might be becuse of the BL difference between the field observtion (7 cm) nd the decision tree (6 cm). Furthermore, to estimte the whole SEF s performnce, we determined the following eqution: E w 1 N r N 1 c E p N r N (1) c 1 1 where E w is the estimtion of the whole SEF, N r is the totl number of routes to scend the SEF, N c : number of chnnels on route, nd E p is the estimtion for chnnel-pool pir using the decision tree. We counted up ll possible routes, N r, for Ayu to scend the SEF. The totl number of routes to scend the SEF ws 171,071, 192, nd 1,584 for experiments 1, 2, nd 3, respectively. Figure 9 shows the reltionship between the estimtion of the whole SEF s performnce, E w, nd the scent success rte within 30 minutes, which ws positive. This ws lso true for different time spns of 15 to 30 min. This indictes tht our estimtion model successfully explined the efficiency of the Fushino River SEF

10 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 Fig. 8 - Overll pssbility bsed on the decision tree for BL6 Ayu. Ascent success rte within 30 minutes [%] Exp. 2 Exp.3 Exp.1 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 Estimtion of whole SEF (E w ) Fig. 9 - Reltionship between the estimtion of whole SEF nd the scent success rte within 30 minutes. CONCLUSIONS We developed decision tree to estimte the pssbility of chnnel nd pool pir in n SEF, bsed on lbortory experiment. Then, we proposed n eqution to estimte the whole SEF, combining the estimtion results of the decision tree. The estimtion eqution showed good reltionship with the fish scent success rte of the field

11 Journl of Wter nd Environment Technology, Vol.13, No.1, 2015 experiments. With this reserch we provided frmework for SEF estimtion. To increse the pplicbility of this method to other SEFs, experiments with different conditions would be required. REFERENCES Fujihr M. nd Chhtkuli S. (2006) Numericl flow modeling over semi-sphericl obstructions in series - Towrd numericl modeling of nture-like fishwys embedded with stones. Trns. Jpn. Soc. Irri. Drin. Reclm. Eng., 74(6), Hullet D. T. (2006) Use decision tree to mke importnt project position. M Network. Ishid R. (1976) An investigtion of spwning behvior of the Ayu. Anim., 43, (in Jpnese) Miyzono M. nd Tomtsu O. (2003) Arrngement of protruding boulders in slnted fishwy. J. Jpn. Soc. Eros. Control Eng., 56(1), (in Jpnese) Miyzono M., Tkuzi T. nd Tomtsu O. (2005) Hydrulic chrcteristics nd nttoril ction of fish round boulders. J. Jpn. Soc. Eros. Control Eng., 57(5), (in Jpnese) Nkmur S. (1995) Gyodou no Hnshi (Story of Fishwy), Snki-do, Tokyo, Jpn, pp (in Jpnese) Noguchi H., Sekine M., Wtnbe M. nd Ukit M. (2007) Study on the quntifiction of environmentl preference of yu by indoor experiment focusing on the river locl environment. Environ. Eng. Res., 44, (in Jpnese) roject Tem "Mizube no Kowz" (2007) Mizube no Kowz (smll restortion works in the wterside). Civil nd Architecture Section of Ymguchi refecture, Jpn. (in Jpnese) Sekine M., Noguchi H., Imi T. nd Higuchi T. (2009) Modelling fish preference for wter gps to determine migrtion pth. roc. 7th Interntionl symposium on ecohydrulics, Jn., Concepcion, Chile. (CD-ROM)