Aqut. Living Resour., 349-36 (9) EDP Sienes, IFREMER, IRD 9 DOI:.5/lr/947 www.lr-journl.org Aquti Living Resoures Effets of temperture, stoking density nd frming onditions on fin dmge in Europen se ss (Dientrrhus lrx) Jennine Person-Le Ruyet nd Niols Le Byon Ifremer, Centre de Brest, Physiologie fontionnelle des Orgnismes mrins, UMR 67, BP 7, 98 Plouzné, Frne Reeived 5 My 9; Aepted Otoer 9 Astrt This pper presents non invsive, rpid nd relile wy to quntittively ssess fin erosion in se ss (Dientrrhus lrx). The method is sed on visul ssessment of fin profile nd re loss of ll fins exept the nterior dorsl, on sle from to 4 in omprison with perfet fin. The effets of stoking density (SD) nd temperture on fin dmge were investigted under experimentl onditions ( 5 g fish). Over 4-month period, men erosion index (men erosion level of ll fins) ws times higher t thn t kg m 3,wheremostfins were undmged. Dmge ws lso dependent on time nd oxygen onentrtion (35% lower t 53% O sturtion thn t 5%). Fin ondition ws lso ffeted y temperture: men erosion index ws..5 t 3 6 C, ut five times higher t 5 C. Cudl nd dorsl fins were lwys the most eroded. Fin dmge ws then monitored in lrge lnd-sed frm using high SD, nd in smll se ge frm operting t low SD. At the first site, 6 thes of two mrket size groups were exmined: L (85 93 g, 5 8 kg m 3 ) nd S (375 4 g, 4 6 kg m 3 ). Fin ondition ws good in ll thes (men erosion index,..3) nd lowest t the highest SD. At the seond site, four thes of lrge fish (35 89 g, 6 4 kg m 3 ) nd four other groups elow mrket size ( 7 g, 8 6 kg m 3 ) were exmined. Fin erosion ws the highest in lrge fish (men erosion index,..) nd in the se ges most exposed to limti disturnes. In oth sites, the most eroded fins were the udl nd dorsl. Differenes in other externl injuries were lso oserved etween the two sites (less nerosis nd more sle injuries in se ges). The uses of fin dmge re disussed in reltion to metoli nd/or ehviorl dpttions to rering onditions nd the min tions tht ould e tken to improve fin ondition re disussed. Key words: Se ss / Fin dmge / Welfre / Temperture / Stoking density / Rering systems Résumé Cet rtile dérit une méthode onservtive, rpide et file pour quntifier l érosion des ngeoires de r (Dientrrhus lrx). Elle est sée sur l évlution visuelle du profil et de l rédution de tille de toutes les ngeoires suf l dorsle ntérieure, sur une éhelle de à 4 en omprison ve une ngeoire prfite. Les effets de l densité de stokge (SD) et de l tempérture sur l étt des ngeoires sont évlués expérimentlement (poissons de 5 g). Après 4 mois, l index moyen d érosion (niveu moyen d érosion de toutes les ngeoires) est fois plus élevé à qu à kg m 3 où l pluprt des ngeoires est intègre. L perte d intégrité est dépendnte du temps et de l onentrtion en oxygène (35 % plus file à 53 qu à 5 % de sturtion en O ). L étt des ngeoires est ussi ffeté pr l tempérture : index moyen d érosion de,,5 à 3 6 C, mis 5 fois plus élevé à 5 C. Les ngeoires les plus érodées sont l udle et l dorsle postérieure. L étt des ngeoires est ussi évlué d une prt, dns une ferme d élevge de grnde tille utilisnt des ssins et des densités élevées et d utre prt, dns une ferme de petite tille utilisnt des ges et de files densités. Sur le premier site, 6 lots de tille ommerile sont exminés : L (85 93 g, 5 8 kg m 3 ) et S (375 4 g, 4 6 kg m 3 ). L étt des ngeoires est on dns tous les lots (index moyen d érosion,, à,3) et moindre ux densités élevées. Dns le seond site, 4 lots de poissons de grnde tille (35 89 g, 6 4 kg m 3 ) et 4 lots en dessous de l tille ommerile ( 7 g, 8 6 kg m 3 ) sont exminés. L érosion des ngeoires est l plus forte hez les gros poissons (niveu moyen d érosion,,,) et dns les ges les plus exposées ux perturtions limtiques. Dns les deux sites, les ngeoires les plus érodées sont l udle et l ngeoire dorsle postérieure. Des différenes de l étt pprent des poissons sont ussi oservées entre les deux sites (moins de néroses et plus de lésions des éilles hez les poissons en ge). Les uses des lésions des ngeoires sont disutées, en reltion ve les justements du métolisme et/ou du omportement ux onditions d élevge, insi que les priniples tions à mettre en œuvre permettnt d méliorer l étt des ngeoires. Corresponding uthor: jperson@ifremer.fr, jennine.person@ornge.fr Artile pulished y EDP Sienes
35 J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) Introdution Fish mintin their position in wter nd ope with their environment through onstnt djustments of swimming tivity. The role of different fins in propulsion nd mnoeuvring is shred in omplex mnner etween the pired nd medin fins. In the wild, s on frms, fish re exposed to ftors tht my dmge their fin tissues (erosion, nerosis, splitting or fin tissue losses). Suh dmge my result from physil or hemil uses or from disese (see Ellis et l. 8 for review). Beuse fin profile hnges re visile nd potentilly esy to quntify, fin ondition hs long een onsidered s useful inditor of fish helth sttus. For re-stoking progrms, reltive fin length is ommonly used s n inditor of juvenile qulity s it is highly ffeted y rering onditions suh s sustrte, temperture, wter qulity, feeding nd wter veloity (Wgner et l. 996; Winfreeetl.998; Brrows nd Lellis 999; Arndt et l. ; Pelis nd M- Cormik 3; Ellis et l. 9). The pthology of fin erosion hs een desried in mny speies nd sometimes using other orgnismi indies; fin injuries re ommonly used to sore fish helth ondition on frms (Goede nd Brton 99; Turnull et l. 996; Ltremouille 3; St-Hilire et l. 6). Fin ondition n lso provide reltively simple nd rpid inditor of fish welfre, relting to the qulity of life or stte of well eing of fish (Conte 4; Huntingford et l. 6; Ashley 7). Fin ondition is potentilly etter in the wild thn in intensive frming where, in oth ggressive nd non ggressive fish, the min risk ftors re stoking density, wter qulity, feeding nd routine hndling (Moutou et l. 998; MLen et l. ; Ltremouille 3; North et l. 6,; Rsmussen et l. 7; Hoyle et l. 7; Ellis et l. 8). In intensive quulture, studies on the frequeny nd severity of fin dmge nd its uses hve foused on slmonids tht re ommonly ffeted oth in freshwter nd se wter (Turnull et l. 998; North et l. 6,; St-Hilire et l. 6; Rsmussenetl.7; Noleetl.7, 8; Person-Le Ruyet et l. 8; Ellis et l. 8; Good et l. 9; Roque et l. 9; Korsoen et l. 9). In rinow trout (Onorhynhus mykiss) frms, St-Hilire et l. (6) showed tht fin injuries were dependent on fish size, tht the petorl nd dorsl fins were the most eroded nd tht there ws high vriility etween individuls nd different frms. In speies where ggression is ommon, ny ftors tht inrese ompetition etween fish, suh s size heterogeneity, restrited feeding nd feeding method, will inrese fin dmge, s shown in Arti hrr (Slvelinus lpinus) (Dmsgrd et l. 997), Atlnti slmon (Slmo slr) (Turnull et l. 5; Nole et l. 7, 8) nd rinow trout (Nole et l. 7). In rinow trout fed to stiety, we previously showed tht the frequeny nd prevlene of dmge to dorsl nd petorl fins ws influened y stoking density (dmge inresed s stoking density, SD, inresed), wter qulity (more dmge where wter qulity promoted feeding tivity) nd fish size (higher in lrge fish), inditing tht fin ondition my e ffeted y rowding, metoli tivity or oth (Person-Le Ruyetetl.8). In the sme speies, fin erosion ws seen to e lower in flow-through system rther thn re-irulted system with higher wter veloity (Roque et l. 9). Using re-irulted systems, Good et l. (9) showed tht for unexplined resons poorer udl fin ondition ws ssoited with low wter exhnge rte. Studies on fin dmge in other frmed fish speies re sre. In od (Gdus morhu) juveniles, it hs een shown tht the inidene of fin dmge used y ggressive ehviour ws high nd inresed signifintly under restrited feeding (Htlen et l. 6). To our knowledge, when reent studies looked t se ss (Dientrrhus lrx) or se rem (Sprus urt) welfre sttus in reltion to stoking density or stress onditions, they hve not inluded fin dmge in their lists of diret or indiret welfre inditors, ut hve onentrted on growth performnes, lood prmeters nd tissue omposition (Ronrti et l. 6; Di Mro et l. 8; Smmouth et l. 9). The purpose of this study ws to investigte the effets of some environmentl risk ftors (temperture nd SD) on fin dmge under ontrolled experimentl onditions. This first required us to develop method for ssessing fin erosion in juvenile nd dult se ss. Fin dmge ws then monitored on two frms representing extreme rering onditions: lndsed frm produing 5 tons of se ss per yer t high SD nd se ge frm produing less thn tons of orgni fish per yer. The diret uses of fin dmge relted to rering onditions re disussed with regrd to possile welfre tions tht my e tken to improve fin ondition nd enhne fish welfre. Mteril nd methods. Fin dmge ssessment method To understnd the mehnisms nd kinetis of fin erosion, severl thousnd juveniles nd dults from different origins (pond ulture, experiments or wild fish) were exmined using method previously desried for rinow trout (Person-Le Ruyet et l. 7). Fish were nesthetized (ethylene glyol monophenyl ether,..5% ) prior to exmintion for fin erosion, other fin dmge nd skin injuries in representtive smple of fish (3 fish under experimentl onditions nd 5 fish minimum under frming onditions, to limit ny possile is of the smpling proedure). Fin erosion ws defined s hnge in totl fin re nd ws estimted y fin profile omprison ginst perfet fin (Fig. ) nd disussed in results. The erosion prmeters re lulted from erosion levels of ll fins s follows. Erosion index per ondition: men erosion level of the 7 fins of ll fish smpled per experimentl ondition nd per smpling dte; Erosion level per fin: men erosion level of speifi fin of ll fish exmined per experimentl ondition; Erosion ourrene: the reltive frequeny of the 5 erosion levels reorded in ll fins of ll fish exmined per experimentl ondition. Under frming onditions, splitting index ws lulted for ll fins nd for the udl fin seprtely, s follows.
J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) 35 Erosion level Petorl (left) Pelvi (left) Dorsl (posterior) Anl Cudl 3 4 Fig.. Chnges in profile of medin nd pired fins used to identify the 5 erosion levels for se ss juveniles nd dults. Splitting index per fish: men numer of splits per fish lulted for ll fins of ll fish smpled from eh of the prodution onditions; Cudl splitting index: men numer of splits of speifi fin of ll fish exmined in eh of the prodution onditions.. Assessment of potentil risks ftors under experimentl onditions The long-term effets of two ftors, stoking density (SD) nd temperture, tht n use dmge to se ss fins were investigted under experimentl onditions using flow through systems nd.5 m 3 squre tnks. The photoperiod ws mintined t 8L:6D nd mximum light intensity ws 5 lux t the wter surfe. The exhnge Fish were fed ommeril extruded diet (Le Gouessntr, protein 44.% nd rude ft.5%) to pprent stiety... Stoking density Se ss (initil weight, 8 g) were held for 4 months t loworsdthtinresedfromtokgm 3 or from 9 to 8 kg m 3 over the ourse of the experiment (groups mrked with the prefix or in Tle ). Eh group ws divided into high nd low O onentrtion su-groups (Ho nd Lo) where O onentrtion ws heked dily prior to feeding nd djusted to SD when neessry using either wter ner O sturtion or wter supplemented with O using the devie desried in Person-Le Ruyet et l. (), i.e. pure oxygen injetion in desturted se wter. In Ho groups, wter flow rte ws 33% per hour t kg m 3 nd 44% per hour t kg m 3.TheO onentrtions hieved t low SD were or 8% (ph, 8.) for Ho nd Lo, respetively, nd t high SD they were 6 or 53% (ph ws lower in Ho thn in Lo, 7.4 nd 7.7, respetively). Temperture ws 9 ±. C(SE) nd fish were fed fixed diet, regulrly djusted to fish demnd nd provided y n utomti feeder. The 4 experimentl
35 J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) Tle. Dt (men ± SE) to fish nd wter qulity in the stoking density experiment. Mens re given with SE; fish weight, n = 3; O onentrtions, n = ; ph, n = 5. Growing Dy Stoking density O ph Weight Survivl onditions (kg m 3 ) (%) (g) (%) -Ho. 79.9 ± 4.5 9 7. ±.7 8. ±. 57.7 ± 5.8 4.3 35. ± 8. -Lo.9 93.3 ± 5.8 9 8.7 8 ±. 8. ±. 3.3 ± 9.5 4.6 33.4 ±. -Ho 9.9 85. ± 5.6 9.7 6 ±. 7.4 ±. 47.8 ± 7.3 99 4 8.3 44.5 ± 6.8 98 -Lo 9.9 77. ± 5.8 9 8.3 53 ±.8 7.7 ±. 3.4 ±5.5 99 4. 34. ± 6.6 99 onditions were thus -Lo, -Ho, -Lo nd -Ho (no replite). At dys 9 nd 4, ll fins exept the nterior dorsl were exmined y single opertor in 3 fish per tnk ( fins totl) to quntify the erosion level per fin nd lulte the different erosion indies. At the strt of the experiment fin ondition ws high nd similr in ll groups... Temperture Duplited groups of se ss juveniles (initilly 84 fish) were rered t 6 onstnt tempertures (3, 6, 9,, 5 or 9 C) for 84 dys (Tle ). They were mintined under O onentrtions lose to sturtion using wter supplemented with oxygen s in the previous experiment nd exhnge rte of 6% h to seure high wter qulity in ll groups. All fish were weighed every two weeks for growth performnes, some individuls were smpled regulrly to ssess helth sttus nd their removl llowed us to mintin stoking density elow3kgm 3 (for detils see Person-Le Ruyet et l. 4). At dy 84, fin dmge ws ssessed in 4 fish per temperture tretment (6 8 fins totl)..3 Fin dmge monitoring under prodution onditions Fin dmge nd other externl injuries were monitored in two se ss frms representtive of intensive nd extensive prodution in Frne. The first ws lrge lnd-sed frm using flow-through systems nd high stoking density, nd the seond smll frm produing orgni fish in se ges loted in the open se..3. Intensive lnd-sed frm The seleted lnd-sed frm is the Frenh leder for se ss nd se rem prodution (5 tons per yer totl, 6% se ss). It is supplied with heted industril wter nd opertes t finl stoking density round 6 kg m 3. Two mrket size lsses of se ss were seleted (S nd L: out 4 nd g, respetively) provided y the sme hthery (Tle 3). Fish were held under usul frm onditions until smpling: 6 m 3 rewy tnks,.4 C, O ner sturtion nd feeding using utomti feeding devies with omputer monitoring. The prodution yle ws 54 weeks for 4 g fish nd 97 weeks for kg fish. There were no mjor sesonl growth disturnes within the nnul temperture rnge, 6.5 5 C. In eh of the 6 thes monitored (3 for the S group nd 3 for the L group), 5 fish were rndomly smpled nd exmined for fin dmge (erosion, splitting, ry deformity or nerosis) nd other externl injuries (sle mrks). Results were reorded for eh size lss (S or L) nd stoking density (represented y suffix numer in Tle 3). Condition ftor ws lulted s weight L 3..3. Se ge frm Fin dmge ws ssessed in seond frm using floting se ges loted in sheltered Mediterrnen y exposed to Estern storms for 8 dys per yer. This ertified orgni fish frm produes less thn tons per yer in open se onditions t low stoking density, 5 kg m 3 mximum t the end of the prodution yle. Eight thes of fish, initilly supplied y ommon lol hthery t 5 g, were ompred ording to fish size ( 9 g), ge volume (8 nd m 3 ) nd lotion in the y (exposure to wter urrents nd storms with high winds). In eh ge, 5 fish were rndomly smpled, nesthetized prior to overlnd trnsport (in wter supplemented with oxygen) nd exmined for fin dmge nd other externl injuries. Min th hrteristis re given ording to fish weight nd time spent on site, i.e. to 4 months (Tle 5). Men nnul temperture ws 6.5 C (extremes:. nd 4.7 C). As growth stops ompletely for 4 5 months per yer, 3 summers re required to produe kg fish. During the prodution yle, fish were grded t nd g in order to limit fish rowding nd relted stress during hndling. Fish re fed y hnd on demnd nd the numer of mels per dy djusted ording to limti onditions.
J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) 353 Tle. Dt relted to fish nd wter qulity in the temperture experiment. Mens re given with SE; dy fish weight, n = 68 nd dy 84, n = 4; O onentrtions, n = 84; ph, n =. Temperture Men weight Stoking density O ph ( C) (g) (kg m 3 ) (%) Dy 84 Dy Dy 84 Dy Dy 84 Dy 84 Dy 84 3.4 ±. 8.3 ±. 8.9 ±.3 6.3 4.7 96 ± 8 8. ±. 6. ±. 8.4 ±. 4. ±. 6.3 7.4 4 ± 8 8.5 ±.7 8.9 ±. 8.9 ±. 79. ± 3.4 6.4. 9 ± 9 8. ±..9 ±. 8.7 ±. 9.5 ± 3.8 6. 5.9 6 ± 8 8. ±.3 4.9 ±. 8.9 ±. 4.4 ± 4.7 6.4 9.9 7 ± 7.97 ±.3 8.8 ±. 8.6 ±. 7.4 ± 5. 6.5 8. 9 ± 8 7.96 ±.3 Tle 3. Min hrteristis of fish exmined ording to prodution onditions in tnks. Men weight is given with SE (n = 5). Size Bth Volume (m 3 ) Men weight Fish Stoking density Time from lst grding (g) numer (kg m 3 ) (week) S4 4 4 ± 3 6 74 4 S S48 78 47 ± 7 34 48 5 S58 96 375 ± 9 4 948 58 4 L49 49 97 ± 6 8 7 49 5 L L6 78 853 ± 75 6 5 L79 96 854 ±.3 4 359 79 5 Tle 4. Additionl fin nd skin dmge in the 6 thes exmined t the lnd-sed frm. Fish exmined for whole ody nd ll fins, n = 5; split index is given for ll fins nd for udl (rket); nerosis ourrene is given for whole ody nd for ll fins (rket). Split index Ourrene (% of fish) Size Bth All fins (udl) Nerosis Fin ry deformity Sle mrks Whole ody (fin) S4.54 (.76) 3 () 4 S S48.68 (.74) 48 () 6 S58.45 (.8) 48 (3) 38 4 L49.43 (.6) 34 (4) 74 L L6.53 (.) 6 (5) 36 L79.88 (.56) 8 (6) 64.4 Sttistil nlysis All results were expressed s men ± stndrd error (SE). The effets of the experimentl onditions tested on fin erosion prmeters nd ll studied prmeters were ompred y ANOVA followed, when neessry, y post ho test. Under frming onditions the different thes monitoredwere tested y ANOVA. 3 Results 3. Fin dmge ssessment method Se ss hve 8 fins, inluding pired fins nd dorsl fins. In ll fins exept the nterior dorsl, the min soft rys develop severl dihotomies towrds the front tip; 3 short spiny rys re lso present t one tip, exept in the udl. The nterior dorsl is short with exlusively spiny rys tht re often exposed (i.e. when the tissues re stripped from the fin ry); it ws exluded from erosion ssessment euse it is usully dmged y hndling nd therefore diffiult to ssess. Dmge first ourred in the front tip of most fins, with progressive derese in the length of soft rys leding to progressive loss of fin re. Fin profile ltertion ws different in the udl fin, where the two externl tips were first eroded. Splitting ( more or less deep ut etween two rys) is ommon in the fins most exposed to mehnil shoks, nd is explined oth y fin ntomy nd ehviourl response to stress. It rnges from minor V form (reent or heled erosion) to deep splits (ute erosion) nd, together with roken or missing rys, my ontriute to the loss of fin re nd funtion. Fin thikening ours s result of disese or heled erosion, nd lood spots or nerosis re ovious signs of tive erosion or infetion. The prevlene of olded rys or sle loss re noted s dditionl externl injuries. Fin erosion is defined s hnge in totl fin re due to ute or heled erosion nd is estimted y fin profile omprison ginst perfet fin. The method is sed on visul ssessment of fin ondition of ll fins exept the nterior dorsl, on sle from to 4 (Fig. ). The progressive loss in fin re, s defined in Fig., ws estimted from imge nlysis, nd totl fin loss ws lulted to determine n upper limit per erosion level: Level : perfet fin, ll fins with extremities intt;
354 J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) Tle 5. Min hrteristis of fish exmined ording to prodution onditions in se ges. Men weight is given with SE (n = 5). Bth Volume Stoking density Men weight Fish Time in ges Distne from y (m 3 ) (kgm 3 ) (g) numer (month) mouth (m) C 8. ± 5 8 95.5 35 P 8.4 59 ± 3 546 7.6 M 9. 96 ± 9 7.6 3 C5 8 6.4 67 ± 5 4 89 7.6 6 M 6.6 358 ± 5 9 6.3 3 P7 5.7 48 ± 5 7 697 3. 87 P3.3 474 ± 4 4 75 3. 73 P3 3.7 885 ± 5 366 4. 77 A Dy 9 Dy 4 Men erosion index Ourene erosion (%) 8 6 4 B 8 6 4 3 4 -Ho -Lo -Ho -Lo -Ho -Lo -Ho -Lo Fig.. Men (± SE) erosion index (A) nd erosion ourrene per level (B) t dys 9 nd 4 in eh of the experimentl onditions tested: nd kg m 3 finl stoking density, nd Ho nd Lo, high nd low O onentrtions. Vlues with different letters t the sme dte re signifintly different (p <.5). Level : no serious hnge in totl fin re (<%), ut hnge in fin profile with miro-splits on the front tip (indented white rings) or exeptionlly one deep len split (>/ fin length); Level : moderte derese in totl fin re (<%) without mrked hnges in fin profile, presene of less thn 5 minor V form splits (depth </3 of fin length) or of one deep len split (>/3 fin length); Level 3: mrked derese in totl fin re (<5%) nd mjor hnges in fin profile, with mny splits (> 5 minor splits or t lest 3 mjor splits), ommon fin thikening ut sene of lood spots or nerosis; Level 4: short nd dysfuntionl fins, mrked loss of totl fin re (> 5%), mny mjor dmges with extensive tissue degrdtion, ommon leeding spots nd seondry infetions. The erosion prmeters re lulted from erosion levels of ll fins s desried in the method setion. 3. Assessment of potentil risks ftors under experimentl onditions 3.. Stoking density During the 4-month experiment, survivl ws ner mximum in ll groups. Growth ws high t low SD where O onentrtion ws higher, exept in the -Lo group (s there ws no supply in oxygen deprived wter in this tretment). At high SD, no growth hd ourred y the end of the experiment irrespetive of O onentrtion. In resting fish, swimming ws errti t low SD. At high SD it ws orgnized nd direted ginst wter urrent. Men erosion index ws very low t kg m 3 nd in the sme rnge t dy 9 nd 4 for oth O onentrtions,.6.5 (Fig. ). At dy 9, it ws muh higher t thn t kg m 3,.9 nd. respetively. At high SD, men erosion index ws dependent on time nd oxygen onentrtion: t dy 4 it ws.5 in O oversturted wter nd signifintly
J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) 355 L pe DDy 9 Petorl L pe Dy 4 Men erosion index L pel dy 9 Pelvi L pel d4 Men erosion index Men erosion index Men erosion index Men erosion index A dy 9 dy 9 dy 9 Anl Dorsl Cudl -Ho -Lo -Ho -Lo A d4 D C d4.37 -Ho -Lo -Ho -Lo Fig. 3. Men (± SE) erosion index t dys 9 nd 4 of left petorl nd pelvi, posterior dorsl, nl nd udl fins ording to experimentl onditions (see Fig. legend). Vlues with different letter t the sme dte re signifintly different. lower (.) under hypoxi onditions. At low SD, perfet fins were predominnt, with 9% of level, nd t high SD they were only 3 %. At high SD, the frequeny of level inresed from less thn % t dy 9 to 3 4% t dy 4 nd ws greter t the highest O onentrtions. In ll groups, the posterior dorsl nd udl fins, tht re prtiulrly exposed to mehnil shoks during rowding, were the most eroded (Fig. 3). In the pired fins there were no signifint differenes in fin erosion etween the right nd left side, lthough oth right pelvi nd petorl were slightly more eroded thn left ones (results not shown). Splitting of the udl fin ws lso noted t high SD t the end of the experiment, ut there ws no other mjor fin or skin dmge (leeding, nerosis, olded fin rys or sle mrks). This experiment showed tht long-term exposure to very high stoking densities ( kg m 3 ) is risk ftor tht my impir fin ondition irrespetive of O onentrtion ( wter qulity prmeter) in the rering environment.
356 J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) A Petorl Men erosion index Ourene erosion (%) 8 6 4 B 3 6 9 5 9 3 6 9 5 9 Temperture ( C) Fig. 4. Men (± SE) erosion index (A) nd erosion ourrene per level (B) t dy 84 in reltion to temperture. Vlues with different letter t the sme dte re signifintly different (p <.5). 3.. Temperture Fish in this experiment were mintined in high qulity wter, there ws no mortlity nd growth ws strongly ffeted y temperture (Tle ). No severe fin or skin dmge ws oserved t ny temperture, lthough ll fish were individully weighed 7 times over the ourse of the experiment. Fin erosion level ws ffeted y temperture nd ws mximl t 5 C(Fig.4). Men erosion index ws very low t 3 6 C (..5), ut ws five times higher t 5 C. It ws lso signifintly lower t 9 Cthnt5 C (.5 ompred to.9). At 3 nd 6 C, the ourrene of level ws 78 nd 73% respetively ompred to % t 5 9 C. For level, it ws 7% t 3 6 C nd out three times higher t 5 9 C. Cudl nd posterior dorsl fins were the most eroded (Fig. 5). The pired fins were slightly dmged in similr wy on the left nd right sides. This experiment showed tht fin dmge ws greter t high temperture thn in old wter (s fish were smller, less tive nd with lrger spe). 3.3 Fin dmge monitoring under prodution onditions 3.3. Intensive lnd-sed frm The fish exmined were representtive of urrent mrket sizes (Fig. 6). For group L, stoking density rnge ws 5 to 8 kg m 3 nd fish hve not een hndled for grding from 6- months (Tle 3). All fish exmined looked helthy with no pprent signs of poor welfre or stress. d 3 4 Men erosion index Men erosion index Men erosion index Men erosion index Men erosoin index Pelvi Anl Dorsl Cudl 3 6 9 5 9 Temperture ( C) Fig. 5. Men (± SE) erosion index t dy 84 of left petorl nd pelvi, posterior dorsl, nl nd udl relted to temperture. Vlues with different letters re signifintly different. Fin ondition ws high nd men fin erosion index rnged from. to.3. The ourrene of level ws 5 6% nd tht of level 3, 3 5% (Fig. 7). The oserved differenes in fin erosion of S groups nnot e esily explined y differenes in fish size or rering onditions. In lrge fish (8 9 g) severity of fin erosion inresed with stoking density. The most eroded fins were the posterior dorsl nd udl, nd pired e d
J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) 357 Men weight (g) 8 6 4 S NS 8 6 4 L.5 S4 S48 S58.5 L49 L6 L79 K.4.3.4.3. S4 S48 S58. L49 L6 L79 Fig. 6. Men (± SE) weight nd ondition ftor (K) of the 6 thes exmined t the lnd-se frm. Vlues with different letters re signifintly different. fins were ffeted in the sme wy (left fin results only shown in Fig. 7). The other externl injuries oserved on whole fish or speifi fins re detiled in Tle 4. Fin splitting ws ommon in ll thes, with split index etween.43 nd.63, exept in th L79 (.9). The udl fin ws more suseptile to splitting thn the other fins: udl splitting index ws thus out 3 times higher thn tht for ll fins. Fin ry deformities were lso oserved on posterior dorsl fins, with n ourrene of 5% nd 6% in S nd L groups, respetively. Nerosis spots were present on fins nd whole ody with higher prevlene in lrge thn in smll fish. In % of the fish, sle mrks ( m 3 re with sle normlities resulting from reovery following sle loss) were lso present on oth right nd left sides. This survey showed tht fin ondition ws high in mrket size fish under intensive frming onditions using oth short prodution yle nd high SD. There ws good orreltion etween split index (y) nd erosion index (x), s shown y the regression eqution: y =.846 x.563; r =.87, suggesting tht the ourrene of splits on ll fins my e used s rough inditor of fish welfre when it is not possile to ssess fin erosion using the min method we desrie. 3.3. Se ge frm In the four thes tht were elow the smllest mrket size of 3 g, men fin erosion index ws.9 exept in one th (M) where it ws out 35% higher (Figs. 8 nd 9). In lrge fish, men erosion index ws higher (..), whih resulted from higher ourrene of level ( 5%) thn in smll fish. It ws in the sme rnge s the most highly ffeted th of smll fish (M). The fins tht were the most vulnerle to erosion were the udl, posterior dorsl nd petorl (Fig. ). This ltter result ws unexpeted. The oserved differenes in fin erosion etween thes were due more to se ge lotion in the y in reltion to urrents nd storms thn to fish size (Fig. ). The udl fin ws lso the most vulnerle to splitting: udl split index ws 3 times higher thn it ws for ll fins together (Tle 6). As in tnk rered fish, split index (y) ws relted to erosion index (x) y the eqution: y =.788 x.556; r =.7. Fin ry deformities were low in omprison (mximum, to % in lrge fish) nd there ws no fin nerosis in most thes. Conversely, there ws high prevlene of sle mrks in ll thes (% of the fish exmined), irrespetive of fish size tht my result primrily from indequte grding proedures, or speifi hndling diffiulties in se ges. This monitoring showed tht smll fish generlly hd etter fin profile thn lrge fish, nd fin rsion ws lower in the sheltered res of the y irrespetive of fish size. 4 Disussion We proposed nd evluted non invsive method to ssess fin dmge nd espeilly fin rsion in se ss juveniles nd dults, whih would e esy to use on lrge numer of nesthetized fish. The min diffiulty in estlishing suh method ws the hoie of key with different degrees of erosion tht would limit opertor error, e dpted to oth juvenile nd dults, nd e usle under ny rering onditions or in the wild. The 5 erosion levels proposed re sed on hnges in fin
358 J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) S L Men erosion index S4 S48 S58 L49 L6 L79 Erosion ourrene (%) 8 6 4 S4 S48 S58 3 4 8 6 4 L49 L6 L79 Fin erosion index S4 S48 S58 L49 L6 L79 l pe l pel p dor nl udl l pe l pel p dor nl udl Fig. 7. Men (± SE) erosion index nd ourrene (%) per th nd erosion index of left pired fins (petorl, pelvi), posterior dorsl (p dor), nl nd udl in the smll (S) nd lrge (L) groups of fish exmined t the lnd-sed frm. Vlues with different letters re signifintly different. profile nd visul estimtion of re loss of ll fins with referene to perfet fin. In omprison with other methods there is no need for fin mesurement nd high qulity digitl photos tht would e oth time onsuming nd unprtil using nesthetized fish under some frming onditions (Hoyle et l. 7; Ellis et l. 9). The method proposed ws shown to e opertionl on frms, relile nd esy to use for n opertor with limited experiene; it hs not yet een tested in the wild. All fins exept the nterior dorsl ould e rpidly exmined to ssign n erosion level to eh. It requires reful fin splying for omprison of profile with key. In experiments nd on frms, 3 fins were prtiulrly vulnerle to erosion nd other dmge: the udl (tive in propulsion), posterior dorsl (stilizer, involved in mneuvering, stress nd defense responses) nd petorl (involved in propulsion nd reorienttion). An lterntive to the proposed method would e to ssess fin erosion of seleted fins insted of ll fins, n pproh pplied inresingly in Slmonids (Nole et l. 8; Person-Le Ruyet et l. 8). Reording mjor splits in seleted fins n lso give n overview of fin dmge, s proposed y Turnull et l. 996, ut it gives no indition of fin re loss nd erosion. This study hs shown tht the udl fin is highly sensitive to splitting nd tht, t lest under frming onditions, there is good orreltion etween men split index nd fin erosion index. At lortory sle, stoking density (SD) ws identified s mjor risk ftor for fin erosion: erosion index ws times higher t thn t kg m 3. The negtive effet of high SD ould not e ssoited with wter qulity (fin ondition ws etter under hypoxi onditions) or to ggressive ehvior (no ite mrks). It my result from numerous ftors nd their intertions: limited spe relted to weight gin, rowding during feeding or high wter veloity. It should e noted tht fin ondition ws little impted when SD inresed from 9 to kg m 3 within 4 months: ll fins were fully funtionl with moderte loss of fin re ut no other injuries (leeding or nerosis). Suh high SD re never used over long-period in the most intensive frming, i.e. in re-irulted
J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) 359 Tle 6. Additionl fin nd skin dmge in the 8 thes exmined in the se-ge frm. Fish exmined for whole ody nd ll fins, n = 5; split index is given for ll fins nd for udl (rket); nerosis ourrene is given for whole ody nd for ll fins (rket). Split index Ourrene (% of fish) Bth Men weight All fins (udl) (g) Whole ody nerosis Ry deformity Sle mrks (fin) (ll fins) C.4 (.5) () 4 3 P 59.7 (.54) 4 () 4 8 M 96.44 (.4) () C5 67. (.4) 4 () 8 6 M 358.3 (.94) 6 () 8 6 P7 48.39 (.58) () 4 P3 474.4 (.76) 8 () P3 885.47 (.) () Men weight (g) 8 6 4 A d d e f K.5.4.3 B C P M C5 M P7 P3 P3. C P M C5 M P7 P3 P3 Fig. 8. Men (± SE) weight nd ondition ftor (K) of the thes exmined t the se ge frm. Vlues withdifferent letters re signifintly different. A SD for mximum growth performnes over 63-dy period in re-irulted system ws out 7 kg m 3. Men erosion Ourrene erosion 8 6 4 B C P M C M P7 P3 P3 C P M C M P7 P3 P3 Fig. 9. Men (± SE) erosion index nd ourrene (%) per th exmined t the se ge frm. Vlues with different letters re signifintly different. systems where oth SD nd wter veloity re high. Smmouth et l. (9) reported tht in se ss (35 g) the highest 3 4 It hs lso een shown experimentlly tht fin ondition my e ffeted y metoli tivity under the ontrol of eologil ftors, suh s temperture nd O onentrtion ting, respetively, s determining nd limiting ftors. In se ss, fins were more eroded t elevted temperture thn in old wter s fish were less tive, espeilly when feeding: mel durtion ws shorter nd dily feed intke ws lower, whih led to lower growth rte (Person-Le Ruyet et l. 4). However fin ondition my remin high t very high temperture, over the upper limit for mximum growth. Although fin dmge my e redued y deresing rering temperture (nd thus fish tivity), this my e uneptle for eonomi resons, espeilly in intensive systems where rpid growth is priority. The oserved differenes in fin ondition relted to temperture my e prtly explined y differenes in fish size nd stoking density, etter tnk volume to fish size rtio leding to lower numer of physil shoks etween fish or on tnk wlls. It would e interesting to study the kinetis of fin profile hnges with temperture to etter ssess temperture impt on fin erosion nd splitting of udl nd dorsl minly. Fin ondition ws more impired in se ss held under high O onentrtions thn under low O onentrtions, where fish swimming nd feeding tivity ws lower. A previous study in rinow trout showed tht lower fin erosion in wter with less O nd more mmoni thn ontrol group
36 J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) A Men erosoin index l pe l pel p dor nl udl B C P M C5 M P7 P3 P3 Men erosion index l pe l pel p dor nl udl Fig.. Men (± SE) erosion index of left pired fins (petorl, pelvi), posterior dorsl (p dor), nl nd udl fins of ll fish exmined (A) nd (B) for eh th exmined t the se ge frm. Vlues with different letters re signifintly different. Men erosion 5 5 Distne from y mouth (m) Fig.. The reltionship of men erosion index to se ge lotion in the y, y =.3 +.3; r =.7. ws ssoited with lower feeding tivity (Person-Le Ruyet et l. 8). The hnges in routine fish tivity nd metolism ording to wter qulity or environmentl onditions hve een extensively studied in mny speies, ut fin ondition hs only een ssessed for speifi purposes (Ltremouille 3). At low tempertures young stges of slmonids produed in htheries present longer petorl fin, whih is vitl for re stoking progrms (Winfree et l. 998). In ggressive fish, ny strtegy deresing gonisti ehvior, suh s temperture, SD or feeding regime, leds to improve fin ondition (Moutou et l. 998; MLen et l. ; Rsmussen et l. 7; Noleetl.7, 8). Using ondemnd devies or ontinuous food supply my improve fin ondition y reduing the intensity nd frequeny of mehnil shoks when feeding nd lso y limiting ggressive ehvior. In the two se ss frms monitored in the present study, fin ondition of ll thes exmined ws generlly good, with erosion level previling nd only % of level. The min eroded fins were the udl nd posterior dorsl, s in the experiments onduted under ontrolled onditions, nd there were no ite mrks. The two petorl fins were more seriously dmged in se ges thn in tnks, whih ould result from speifi ehviour nd rsion from ontt with net ges due to wter urrents. In fish elow 35 g, fin erosion ws slightly higher in se ges thn in the two experiments when omprison ws mde t similr SD. For lrge fish, fin erosion ws in the sme rnge for the two sites irrespetive of SD (<5 or out 6 kg m 3 ) nd prodution yle durtion (4 or 3 months for lrge fish). In the lnd sed frm, SD ws mjor risk ftor for fin rsion, under speifi rering onditions of the frm SD of 6 kg m 3 seems preferle t the end of prodution yle. In se ges, ge lotion ws risk ftor: fin erosion ws higher in the ges most exposed to urrents nd wind. There were some differenes in the extent of other types of dmge to fins or whole fish etween the two frms. The min differene ws lk of fin nerosis ut low prevlene of nerosis of the whole ody in se ges, whih my hve een relted to differenes in disese ourrene, husndry frequeny or wter qulity. Husndry prties my explin why fin splitting nd fin ry deformities re more prevlent
J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) 36 in lnd-sed frms thn in se ges, where hndling ws minimized during long prodution yle. The more fish re hndled, the higher the risk of induing fin dmge nd tissue lesions, leding to inresed risk of infetion nd disese espeilly in onfined environment. The high prevlene of sle normlities on the fishes sides in oth sites resulted from reovery fter sle loss tht hd ourred during grding or routine hndling. It ws higher in se ges, where hndling is restrited nd more diffiult thn in lnd-sed frms. In omprison, regulr hndling of smll numer of nesthetized fish is possile in lortory studies without using roken fin rys, tissue lesions or nerosis. To onlude, this study hs shown tht the effets of rering onditions on fin profile hnges operte in omplex wy through metoli nd/or ehviorl influenes. Fin rsion my e minimized y suffiient spe vilility nd y voiding exessive metoli tivity or stress, espeilly during feeding. Se ss n e rered on frms t reltively high SD without signifint fin dmge, ut there is need to improve hndling nd grding proedures tht my impir fish externl pperne. Aknowledgements. This study is ontriution to the BENEFISH Europen progrm. The uthors would like to thnk the SFAM nd stff of the two frms, Aqunord nd Provene Aquulture, who took prt in this study (espeilly F. Gine nd F. Stholz) nd re grteful to the BENEFISH tem. The study ws rried out within the finnil support from the Commission of the Europen Communities, speifi RTD progrmme Speifi Support to Poliies, SSP-5-Fish BENEFISH. It does not neessrily reflet the views of the ommission, nor does it im to present the Commission s future poliy in this re in ny wy. Referenes Arndt R.E., Routledge M.D., Wgner E.J., Mellethin R.F.,, The use of Aqumstsr to enhne growth nd improve fin ondition mong rewy ultured rinow trout Onorhynhus mykiss (Wlum). Aqu. Res. 33, 359 367. Ashley P.J., 7, Fish welfre: urrent issues in quulture. Appl. Anim. Behv. Si. 4, 99 35. Brrows F.T., Lellis W.A., 999, The effet of dietry protein nd lipid soure on dorsl fin erosion in rinow trout, Onorhynhus mykiss. Aquulture 8, 67 75. Conte F.S., 4, Stress nd the welfre of ultured fish. Appl. Anim. Behv. Si. 86, 5 3. Dmsgrd B., Arnesen A.M., Brdvik B.M., Joling M., 997, Stte dependent feed quisition mong two strins of hthery-rered Arti hrr. J. Fish Biol. 5, 859 869. Di Mro P., Priori A., Finoi M.G., Mssri A., Mndih A., Mrino G., 8, Physiologil responses of Europen se ss Dientrrhus lrx to different stoking densities nd ute stress hllenge. Aquulture 75, 39 38. Ellis T., Hoyle I., Oidtmnn B., Turnull J.F., Jklin T.E., Knowles T.G., 9, Further development of the fin index method for quntifying fin erosion in rinow trout. Aquulture 89, 83 88. Ellis T., Oidtmnn B., St-Hilire S., Turnull J., North, B.P., MIntyre C., Nikomidis J., Hoyle I., Kestin S., Knowles T., 8, Fin erosion in frmed fish. In: Brnson E.J. (Eds.), Fish welfre, Blkwell, Oxford, pp. 49. Geode R.W., Brton B.A., 99, Orgnismi indies nd n utopsysed ssessment s inditors of helth nd ondition of fish. Am. Fish. So. Symp. 8, 93 8. Good C., Ddidson J., Welsh C., Brzil B., Snekvik K., Summerfelt S., 9, The impt of wter exhnge rte on the helth nd performne of rinow trout Onorhynhus mykiss in wter reirultion quulture systems. Aquulture 94, 8 85. Htlen B., Grisdle-Hellnd B., Hellnd S.J., 9, Growth vrition nd fin dmge in Atlnti od (Gdus morhu L.) fed t grded levels of feed restrition. Aquulture 6,. Hoyle I., Oidtmnn B., Ellis T., Turnull J., North B., Nikolidis J., Knowles T.G., 7, A vlidted mrosopi key to ssess fin dmge in frmed rinow trout (Onorhynhus mykiss). Aquulture 7, 4 48. Huntingford F.A., Adms C.E., Brithwite V.A., Kdri S., Pottinger T.G., Sndoe P., Turnull J.F., 6, Current issues in fish welfre. J. Fish Biol. 68, 33 37. Korsoen O.J., Dempster T., Fjelldl P.G., Oppedl F., Kristinsen T.S. 9, Long-term ulture of Atlnti slmon (Slmo slr L.) in sumerged ges during winter ffets ehviour, growth nd ondition. Aquulture (in press). Ltremouille D.N., 3, Fin erosion in quulture nd nturl environments. Rev. Fish. Si., 35 335. MLen A., Metlfe N.B., Mithell D.,, Alterntive ompetitive strtegies in juveniles Atlnti slmon (Slmo slr): evidene from fin dmge. Aquulture 84, 9 3. Moutou K.., MCrthy I.D., Houlihn D.F., 998, The effet of rtion level nd soil rnk on the development of fin dmge in juvenile rinow trout. J. Fish Biol. 5, 756 77. Nole C., Kdri S., Mithell D.F., Huntingford F.A., 8, Growth, prodution nd fin dmge in ge-held + tlnti slmon presmolts (Slmo slr L.) fed either ) on-demnd, or ) to fixed stition-restrition regime: Dt from ommeril frm. Aquulture 75, 63 68. Nole C., Kdri S., Mithell D.F., Huntingford F.A., 7, The influene of feeding regime on intrspeifi ompetition, fin dmge ndgrowthin + Atlnti slmon prr (Slmo slr L.) held in freshwter prodution ges. Aqu. Res. 38, 37 43. Nole C., Mizusw K., Suzuki K., Tt M., 7, The effet of differing self-feeding regimes on the growth, ehviour nd fin dmge of rinow trout held in groups. Aquulture 64, 4. North B.P., Ellis T., Dvis J., Bromge N.R., 6, Stoking density prties of ommeril UK rinow trout frms. Aquulture 59, 6 67. North B.P., Turnull J.F., Ellis T., Porter M.J., Migud H., Bron J., Bromge N.R., 6, The impt of stoking density on the welfre of rinow trout (Onorhynhus mykiss). Aquulture 55, 466 479. Pelis R.M., MCormik S.D., 3, Fin development in strem- nd hthery-rered Atlnti Slmon. Aquulture, 55 536. Person-Le Ruyet J., Lé L., Le Byon N., Sévère A., Le Roux A., Le Delliou H., Quéméner L., 8, Comined effets of wter qulity nd stoking density on welfre nd growth of rinow trout (Onorhynhus mykiss). Aqut. Living Resour., 85 95.
36 J. Person-Le Ruyet nd N. Le Byon: Aqut. Living Resour., 349-36 (9) Person-Le Ruyet J., Le Byon N., Gros S., 7, How to ssess fin dmge in rinow trout, Onorhynhus mykiss? Aqut. Living Resour., 9 95. Person-Le Ruyet J., Mhé K., Le Byon N., Le Delliou, H., 4, Effets of temperture on growth nd metolism in Mediterrnen popultion of Europen se ss, Dientrrhus lrx. Aquulture 37, 69 8. Person-Le Ruyet J., Pihvnt K., Vher C., Le Byon N., Sévère A., Bœuf G.,, Effets of O supersturtion on metolism nd growth in juvenile turot (Sophthlmus mximus L.). Aquulture 5, 373 383. Rsmussen R.S., Lrsen F.H., Jensen S., 7, Fin ondition nd growth mong rinow trout rered t different sizes, densities nd feeding frequenies in high-temperture re-irulted wter. Aqu. Int. 5, 97 7. Ronrti A., Melotti P., Dees A, Mordenti O., Angellotti L., 6, Welfre sttus of ultured sess (Dientrrhus lrx L.) nd serem (Sprus urt L.) ssessed y lood prmeters nd tissues hrteristis. J. Appl. Ihthyol., 5 34. Roque d Orstel E., Person-Le Ruyet J., Le Byon N., Blnheton J.P., 9, Comprtive growth nd welfre in rinow trout rered in reirulted nd flow through rering systems. Aqu. Eng. 4, 79 86. Smmouth S., Roque d Orstel E., Gsset E., Lemrié G., Breuil G., Mrino G., Coeurdier J.L., Fivelstd S., Blnheton J.P., 9, The effet of density on se ss (Dientrrhus lrx) performne in tnk-sed reirulted system. Aqu. Eng. 4, 7 78. Shneider, R., Niholson, B.L., 98, Bteri ssoited with fin rot disese in hthery-rered Atlnti slmon (Slmo slr). Cn. J. Fish. Aqut. Si. 37, 55 53. St Hilire S., Ellis T., Cooke A., North B.P., Turnull J. F., Knowles T., Kestin S., 6, Fin erosion on rinow trout on ommeril trout frms in the United Kingdom. Vet. Re. 59, 446 45. Turnull J.F., Rihrds R.H., Roertson D.A., 996, Gross, histologil nd snning eletron-mirosopi pperne of dorsl fin rot in frmed Atlnti slmon, Slmo slr L., prr. J. Fish Dis. 9, 45 47. Turnull J.F., Adms C.E., Rihrds R.H., Roertson, D.A., 998, Attk site nd resultnt dmge during ggressive enounters in Atlnti slmon (Slmo slr L.) prr. Aquulture 59, 345 353. Turnull J.F., Bell A., Adms C.E., Bron J., Huntingford F.A., 5, Stoking density nd welfre of ge frmed Atlnti slmon: pplition of multivrite nlysis. Aquulture 43, 3. Wgner E.J., Routledge M.D., Intelmnn S.S., 996, Fin ondition nd helth profiles of lino rinow trout rered in onrete rewys with nd without ole sustrte. Progress. Fish Cult. 58, 38 4. Winfree R.A., Kindshi G.A., Shw H.T., 998, Elevted wter temperture, rowding, nd food deprivtion elerte fin erosion in juvenile steelhed trout. Progress. Fish Cult. 6, 9 99.