The Effect of Stocking Density on Growth Parameters and Survival Rate of Rainbow Trout Alevins (Oncorhynchus mykiss)

Transcription

1 World Journl of Fish nd Mrine Sciences 4 (5): , 2012 ISSN IDOSI Pulictions, 2012 DOI: /idosi.wjfms The Effect of Stocking Density on Growth Prmeters nd Survivl Rte of Rinow Trout Alevins (Oncorhynchus mykiss) Hossein Mordyn, Hmed Krimi, Hi Allh Gndomkr, 2 4 Mohmmd Rez Shrein, Sr Erteft nd Homyoun Hosseinzdeh Shfi 1 Genetic nd Breeding Reserch Center for Coldwter Fishes, Shhid Mothri, Ysouj, Irn 2 Deprtment of Fisheries,Acdemic Stff of Jiroft University, Kermn, Irn Deprtment of Fisheries, Fculty of Mrine Science nd Ocenogrphy, Khormshhr University, Mrine Science nd Technology, PB No: 669, Khormshhr, Irn 4 Irnin Fisheries Reserch Orgniztion, P.O.Box Tehrn, Irn Astrct: To evlute the effect of stocking density on survivl nd growth rte of rinow trout levins, fter 10 dys dpttion to the new condition, numers of levins with initil weigh11±0.10 mg nd initil totl length 24±0.2 mm were distriuted rndomly mong 9 stndrd trough with 4000, 6000 nd 8000 fish per trough, respectively, corresponding to iomss stocking densities of 5.28, 7.80 nd kg/m, respectively. The experiments were continued for 45 dys in triplictes. Flow rte of wter ws 7.5 l/min nd photoperiodic of 12h light nd 12h drk per dy ws mintined during the experiment. Physiochemicl prmeters of wter (temperture, ph, Dissolved oxygen nd Totl mmoni nitrogen) were mesured two times dily. Fish were hnd-fed 6 to 8 times dily up to 4% ody weight/dy. Survivl of levins ws significntly lower t high stocking density (group ), the minimum survivl ws in group (74.6%) nd the mximum ws in group 2 (84.8%). Stocking density did not significntly ffected finl weight, specific growth rtes (SGR) nd condition fctors (CF) t the end of the study (P>0.05). The lest food conversion rtio (FCR) ws otined in Group 1 nd Group 2, FCR vlue ws significntly higher in Group (2.) with high stocking density (P<0.05). In Conclusion, rinow trout levins growth nd FCR ws etter t low stocking density. This study lso showed tht high stocking density hd effect on survivl rte of rinow trout levins. Key word: Stocking Density % Growth Prmeters % Survivl Rte % Rinow Trout INTRODUCTION products) [2]. Mny fctors such s oxygen level, fish size, wter temperture, wter flow, ville spce, Incresing in fish frm production hs prtilly relied cron dioxide nd mmoni levels ffect the cceptility on the perfecting of exploittion nd husndry methods. of stocking densities nd tht it is highly complex tsk In this regrd, elevtion of rering density ws initilly to set mximum stocking density for trout. Nevertheless, viewed s promising pproch, which comined the the current stocking density tht frmers use in Irn ws mximiztion of wter use with incresed stock too high for trout nd tht reserch should e undertken production, on the other hnd, there is incresing interest to determine cceptle stocking densities. in the welfre of frmed fish nd stocking density is Fish held t high density re generlly regrded s frequently highlighted s n re of prticulr concern [1]. eing exposed to complex set of inherent fctors It is suggested tht rinow trout on commercil frms intercting with ech other e.g., ltered wter qulity, suffered high incidence of fin injury nd high mortlity, decresed food vilility nd chnges in socil which were linked to high stocking density. The issue of interctions, ll eing potentil sources of stress [-6]. stocking density of fish is complex ecuse it comines Acute nd chronic stress trigger series of defense the ehviorl need for spce with the physiologicl need mechnisms tht re generlly energy demnding nd for wter (to provide oxygen nd dilute nd remove wste therefore induce n elevtion of the niml metolic rte Corresponding Author: Hossein Mordyn, Genetic nd Breeding Reserch Center for Coldwter Fishes, Shhid Mothri, P.O. Box 75914/58, Ysouj, Irn. Tel/Fx:

2 World J. Fish & Mrine Sci., 4 (5): , 2012 [7]. These re likely to e t the source of growth Experimentl Design: The experimentl design ws sed depletion [8-9]. However, only few studies hve on the growth of rinow trout levins t three different ttempted to estimte the extent of the dditionl energy stocking densities. Rinow trout levins (n =100, men requirements ssocited with incresing density [9, 10]. live weight ± stndrd error: 11±10 mg) were divided into Moreover, when density ws ctully found to influence 9 groups (three replictes ech of three stocking fish oxygen demnd, the ioenergetic significnce of tht densities) of similr men weight. Experimentl stocking supplementry expenditure ws not fully evluted. densities (groups 1, 2 nd ) comprised 4000, 6000 nd Despite long history of rinow trout production 8000 fish per trough, respectively, corresponding to dting ck to 1885 [11] nd previous ttempt to iomss stocking densities of 5.28, 7.80 nd kg/m, determine the optiml density of rinow trout levins in respectively. The numers of fish in ech tnk were held commercil trout frms, there re lot of prolems constnt for 45 dys, during which time iomss ssocited with lrvl production in rinow trout frms incresed s the fish grew. Stocking density is not sttic in Irn. Despite the need for high-qulity levins, the prmeter nd the iomss of fish stocked t n initil environment under which the levins re mintined density increses s the fish grow until splitting, This efore introducing to rering frms is often stressful. resulted in finl stocking densities of 7.68, nd However, little informtion hs een generted to kg/m, respectively. determine whether crowding result in mesurle declines Fish mortlity ws recorded every dy. Fish mss in growth performnce. increse ws estimted every other week y individul Thus, differences in growth rtes of rinow trout weighing of 100 fish fsted for 24h for ech tch. Using levins held t three different stocking densities were the dt collected during the study, specific growth rtes exmined with the ims of studying the effect of stocking (SGR), feed conversion rtios (FCR), condition fctors density on growth rte nd vrition within groups over (CF) were determined [15]: time. We selected rnge of prmeters tht re fesile, vlid, repetle nd hve een commonly used to study C Survivl% =100 x (FFNu/ IFNu) [16] where FFNu: the the effects of stocking density on fish (mortlity, growth, numer of fish t nd of rering period nd IFNu: the condition fctor, FCR, weight) [12-14]. numer of fish t eginning of rering period. C SGR=100*[(ln(w t)-ln(w i))/t] MATERIALS AND METHODS C CF=(W/L )x100; C FCR = (Ef k)/(wt-w 0 ); where t: feeding dys (dy), w 0: Experiments were conducted t the Genetic nd initil live weight of fish (g), W t: finl live weight of Breeding Reserch Center for Coldwter Fishes Shhid fish (g), L: totl length (cm) nd f k: weight of feed Mothri Ysouj, Irn, from Mrch 0 to My 10, consumed y fish t ech feeding (g). Fish: Rinow trout levins (O. mykiss) weighing Dt Anlysis: Dt re presented s rithmetic men 11±0.10 mg were initilly distriuted mong nine indoor ±SE. One-wy ANOVA (following Levene s F-test for troughs (100 liter) where they were held for 45 dys t homogeneity of vrince) ws used to test for differences different rering densities. Susequently, fish from ech etween tretments. Where differences were found trough were cclimted for 2 weeks. During rering period, (P<0.05) in multiple comprisons, Tukey s honestly environmentl prmeters (ph, oxygen) were mesured significnt difference (HSD) test ws used to determine two times dily. Oxygen sturtion ws mintined which specific pirs differed. t pproximtely 90%, ph vried etween 7.25 to 8.0. The reltionships etween initil iomss The wter flow rte ws mnully controlled nd djusted stocking density nd oth SGR nd FCR were s fish density incresed to 7.5 l/min. Light ws provided nlyzed using liner regression nlysis. Differences y overhed fluorescent tues on 12-h light: 12-h drk in the slopes of the regression lines etween cycle. The rering troughs were supplied with 11±1 C tretments were nlyzed using t-test. Where multiple erted freshwter diverted from nery spring. Fish comprisons were mde the oserved significnce level were fed commercil diet (trout strter diet, Chineh, Irn) ws djusted ccording to the Bonferroni correction. with dily feeding level rnging during the tril from to Differences in the weight frequency distriution were 4% ody weight, ccording to the wter temperture nd nlyzed using the Kolmogorov Smirnov two-smple fish size. test. 481

3 World J. Fish & Mrine Sci., 4 (5): , 2012 Tle 1: Chnges in wter temperture, ph, oxygen concentrtion nd totl mmoni nitrogen recorded during the tril with rinow trout Groups (numer of levins) Wter qulity prmeters Temperture ( C) 11±1 11±1 11±1 ph 7.6± ± ±0.1 DO (mg/l) 8.7± ±0. 8.1±0.5 Totl mmoni nitrogen (mg/l) Tle 2: Men (±SD) weight, growth, specific growth rte (SGR), feed conversion rtio (FCR), condition fctor (CF), survivl rte nd iomss of rinow trout levins rered in troughs Groups (numer of levins) No of fish per trough Initil weight (mg) 12± ±0.9 12±1.2 Finl weight (mg) 942± ± ±0.59 Initil length (mm) 24.5± ± ±0.2 Finl length (mm) 44.1± ± ±4.1 SGR (% / dy) 4.6± ± ±0.1 FCR 1.1± ±0. 2.±0.4 CF 1.09± ± ±0.04 Survivl (% of initil stock) 81.62± ± ±6.2 Initil iomss (g/trough) Finl iomss (g/ trough) Initil stocking density (kg/m ) Finl stock (kg/m ) Different superscript letters in the sme row denote significnt differences mong the experimentl groups (p#0.05). RESULTS Monthly men wter tempertures rnged ws 11±1 C. Dissolved oxygen content did not show much vrition rnging from 8.1 to 8.7 mg/l, wheres ph vlues lso did not show much vrition nd vried 7.6 to 7.8 (Tle 1). Becuse of wter source no significnt differences were found in wter qulity prmeters. Wter prmeters were lwys perfectly comptile with the requirements of rinow trout levins. Survivl rtes were from74.6 ±6.2 to 84.8 ±.7 for ll groups (Figure 1). There were no significnt difference on survivl mong group 1 nd 2, ut survivl rte ws significntly lower in group compred to group 1 nd 2 (p<0.05). Initil nd finl ody weights nd lengths, specific growth rtes, food conversion rtios nd survivl rtes re presented in (Tle 2). The finl weights of the fish stocked t density of 4000, 6000 nd 8000 fish m reched men weights (±SD) of 942±0.44, 806±059 nd 840±0.61 mg, respectively. There were no significnt differences in weight nd length mong experimentl groups t the eginning of the study nd no significnt Fig. 1: Mortlity pttern in rinow trout levins during experiment period. Group1= 4000 lrve per trough, group 2= 6000 lrve per trough nd group = 8000 lrve per trough. Fig. 2: Tendency of condition fctors to increse during experiment period Group1= 4000 lrve per trough, group 2= 6000 lrve per trough nd group 2= 8000 lrve per trough. differences were found mong replictes of the groups over the course of the experiment. Hence dt from replictes were pooled for ech tretment prior to nlysis. Sttisticlly significnt differences were found etween the first group (4000 levins per 100l) nd the two other groups (6000 nd 8000 levins per 100l) in terms of finl ody lengths (P<0.05). There were no significnt differences in finl weight, specific growth rtes nd condition fctors etween experimentl groups t the end of the study (P>0.05). The highest SGR (4.6%rdy) recorded during the course of this experiment ws for first group stocked with 4000 levins, t the end of experiment. Condition fctors vlues of the groups were clculted t the end of the study, it ws very similr rnging 1.09 to There ws tendency of condition fctors to increse during experiment period (Figure 2). According to Figure 2, condition fctor in ll groups incresed with growth. Feed conversion vlue ws lowest in low stocking density group. The estimted feed conversion rtios 482

4 World J. Fish & Mrine Sci., 4 (5): , 2012 vried etween 1.1 nd 2. nd differences mong groups nd Ridh [22]. Mny uthors [2-26] remrked the were found significnt (p<0.05) in fvor of low nd influence of stocking density on the growth of trout. medium stocking density groups. Reduced growth nd n increse FCR with the incresing of stocking density were found in most of the studies DISCUSSION investigted trout. Furthermore, numerous studies hve investigted the effects of density on productivity ut the Wter prmeters (Tle 1) were lwys perfectly findings re not lwys in greement. In rook chrr, comptile with the requirements of rinow trout levins Hrdy nd Audet [27] oserved tht growth performnces [17]. Wter prmeters didn't show significnt differences were not ffected y density nd interpreted this s n during experiment, so possile vrition in growth cn e exmple of good ppliction of rering mngement nd correlted with stocking density. high wter qulity. When these conditions re not Survivl is key indictor of helth sttus. The men respected, the incresing stocking density leds to survivl rtes of round 74.6 to 84.8 in the present study reduction in food consumption reduced food were similr to those oserved in erlier studies on consumption s consequence of deteriortion in rinow trout levins. The group with 4000 fish showed wter qulity, overcrowding or dverse socil interctions the highest survivl rte (Tle 2). The survivl rte [12, 24, 28]. Despite numerous studied on rinow trout declined significntly in lst stocking density (P<0.05) nd other fishes, there is lck of dt on effect of proly due to high stocking rtio. Other studies on stocking density on fish levins nd lrve. stocking densities reported similr results tht stocking In terms of ehviorl nd other stressful prmeters density hs n effect on survivl rte [18-19]. North et l. some studies reported tht high densities led to [1-14] demonstrted tht provided good wter qulity is ggression nd some welfre prolems tht uthors mintined, it is possile to grow rinow trout t suggest my e due to the existence of dominnce densities of up to 80 kg/m without ffecting growth, CF hierrchy [1]. Ellis et l. [12] concluded tht stocking or mortlity. It is suggested tht rinow trout on density is n importnt fctor for fish welfre, ut cnnot commercil frms suffered high incidence of fin injury nd e considered in isoltion from other environmentl high mortlity, which were linked to high stocking fctors, which is our opinion too. The high numer of density. So stocking density hd effect on survivl rte individul/m which reduced the ility of fish to see nd on high density group. It is notle tht mortlity could ccess food is nother possile reson for the low growth e due to positive interctions etween stressful fctors nd high feeding conversion rtio of fish in high stocking tht thretened fish helth [7]. So we concluded tht density. stocking density hd effect on survivl rte on high Density ws lso found to e potentil source of density group. stress [8, 29, 0], cple of hving consequentil There ws significnt difference etween finl repercussions on fish growth rte [10, 1, 2]. lengths mong lrvl t different stocking density s finl Environmentl stressors re importnt fctors responsile length ws higher in low stocking density groups (4000) tht limit fish performnce under quculture conditions thn group 2 nd. In literture there ws no evidence for [12, ]. When fish re sujected to dverse these differences, ut it my e s result of reduction of environmentl conditions, some endocrine nd ggressive interctions due to the presence of smll physiologicl ltertions occur, often resulting in chnges numer of lrger dominnt fish, s suggested in in the ility of the fish to survive, grow nd reproduce previously pulished work tht showed incresed size [7, 0]. It hs een oserved tht niml under stress need heterogeneity reduced ggression in Atlntic slmon prr to spend more energy for homeosttic processes [4]. [20]. In the other hnd this energy expense for stress thn Growth rte, condition fctor nd SGR were increse growth. The decresed feed utiliztion, therefore, might e with incresing density, ut there were no significnt n indictor of the higher level of stress encountered y differences mong groups. FCR vlues were significntly the fish t higher densities. Mximum increse in fish higher in group thn group 1 nd 2. So, growth nd FCR iomss ws found t the lowest stocking density nd of rinow trout levins were etter t low stocking decresed with incresing density ecuse of etter density compred to the growth nd feeding rtio of fish feed utiliztion nd unstressed conditions t low t high stocking density in our tril. These results re stocking levels. We didn t investigte the ehvior nd similr to those reported y Ppoutsoqlou et l. [21]; Cruz plsm cortisol levels of levins especilly, ut when we 48

5 World J. Fish & Mrine Sci., 4 (5): , 2012 oserved them we didn t see so mny cses of 9. Jorgensen, E.H., J.S. Christinsen nd M. Joling, ggression nd we considered tht the generl 199. Effects of stocking density on food intke, reson for high survivl, growth nd FCR in troughs t growth performnce nd oxygen consumption in low density is result of etter qulity of the wter in them. We concluded tht rinow trout levins growth nd FCR ws etter t low stocking density in our tril. This study lso showed tht high stocking density hd effect on survivl rte of rinow trout levins. Arctic chrr (Slvelinus lpines). Aquculture ACKNOWLEDGEMENTS This work ws conducted in Genetic nd Breeding Reserch Center for Coldwter Fishes (GBRCCF), Shhid Mothri, Ysouj, Irn. We re keen to thnk the stff of the GBRCCF for their skillful technicl ssistnce. REFERENCES 1. Lefrncois, C., G. Clireux, C. Mercier nd J. Auin, Effect of density on the routine metolic expenditure of frmed rinow trout (Oncorhynchus mykiss). Aquculture, 195(-4): Irwin, S., J. O'Hllorn nd R.D. FitzGerld, Stocking density, growth nd growth vrition in juvenile turot, Scophthlmus mximus (Rfinesque). Aquculture, 178: Reftsie, T., Effect of density on growth nd survivl of rinow trout. Aquculture, 11: Joling, M., Physiologicl nd socil constrints on growth of fish with specil reference to Arctic chrr, Slvelinus lpinus L. Aquculture 44: Joling, M. nd T.G. Reinsnes, Physiologicl nd socil constrints on growth of Arctic chrr, Slvelinus lpinus L.: An investigtion of fctors leding to stunting. J. Fish Biol., 2: Pickering A.D nd T.G. Pottinger, Poor wter qulity suppresses the cortisol response of slmonid fish to hndling nd confinement. J. Fish. Biol., 0: Brton, B.A. nd G.K. Iwm, Physiologicl chnges in fish from stress in quculture with emphsis on the response nd effects of corticosteroids. Annu. Rev. Fish Dis., 1: Vijyn, M.M. nd J.F. Letherlnd, Effect of stocking density on the growth nd stress response in rook chrr, Slvelinus fontinlis. Aquculture 75: : Ross, R. nd B.J. Wtten, Importnce of reringunit design nd stocking density to the ehvior, growth nd metolism of lke trout (Slvelinus nmycush). Aqucult. Eng., 19: Gll, G.A.E. nd P.A. Crndell, The rinow trout. Aquculture, 100: Ellis, T., B. North, A.P. Scott, N.R. Bromge, M. Porter nd D. Gdd, The reltionships etween stocking density nd welfre in frmed rinow trout. J. Fish Biol., 61: North, B.P., J.F. Turnull, T. Ellis, M.J. Porter, H. Migud, J. Bron nd N.R. Bromge, The impct of stocking density on the welfre of rinow trout (Oncorhynchus mykiss). Aquculture, 5: North, B., J. Turnull, J. Tylor, T. Ellis nd N. Bromge, Assessing the effects of stocking density on the welfre of frmed rinow trout. Trout News, 8: Boyer, N.J., W. Vn Toever nd M.E. Jnsen, Effect of photoperiod on growth of Arctic chrr under commercil production conditions. Prog. Fish-Cult., 56: Terjesen, B.F., K.J. Lee, Y. Zhng, M. Fill nd K. Drowski, Optimiztion of dipeptide-protein mixtures in experimentl diet formultions for rinow trout (Oncorhynchus mykiss) levins. Aquculture, 254: Huet, M., Textook of Fish Culture: Breeding nd Cultivtion of Fish. Fishing News Books, London, pp: Aksungur, N., M. Aksungur, B. Akulut nd I. Kutlu, Effects of stocking density on growth performnce, survivl nd food conversion rtio of Turot (Psett mxim) in the net cges on the southestern cost of the Blck Se. Turkish J. Fish. Aqut. Sci., 7: Sirkov, I. nd E. Ivnchev, Influence of stocking density on the growth performnce of rinow trout nd rown trout grown in recircultion system. Bulgrin Journl of Agriculturl Science, 14(2):

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