Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Experimental validation of geosmin uptake in rainbow trout, Oncorhynchus mykiss (Waldbaum) suggests biotransformation
Schram, Edward ; Schrama, Johan W. ; Kooten, Tobias van; Kwadijk, Christiaan J.A.F. ; Kampen, Harm ; Kampen, Harm ; Heul, Jan W. van de; Verreth, Johan A.J. ; Murk, Albertinka J. - \ 2018
Aquaculture Research 49 (2018)2. - ISSN 1355-557X - p. 668 - 675.
bioconcentration - biotransformation - geosmin - off-flavour - rainbow trout - water-lipid partitioning
The bioconcentration of waterborne geosmin in rainbow trout, Oncorhynchus mykiss (Waldbaum) was assessed. Fifty rainbow trout with a mean (SD) weight of 226.6 (29.0) g and lipid content of 6.2 (0.6) % (w/w) were exposed to geosmin in static water for 0, 2, 4, 6, 8, 12, 24, 36, 48 and 120 hr, with one tank containing five fish for eac h exposure period. Geosmin concentrations were measured in fish tissue and water samples collected over time. With time the geosmin concentration in the fish increased and decreased in the water. However, the total absolute amount of geosmin in the system declined over time which could be explained by induction of biotransformation. This is in accordance with the decreasing lipid normalized geosmin levels in the liver compared with the liver-free carcass. Geosmin distribution within rainbow trout clearly is not exclusively governed by the lipid content of tissues. In vivo geosmin bioconcentration in rainbow trout is slower and the body burden reached is lower than the generally accepted theoretical model predicts.
Geosmin depuration from European eel (Anguilla anguilla) is not affected by the water renewal rate of depuration tanks
Schram, Edward ; Kooten, Tobias van; Heul, Jan van der; Schrama, Johan W. ; Verreth, Johan A.J. ; Murk, A.J. - \ 2017
Aquaculture Research 48 (2017)9. - ISSN 1355-557X - p. 4646 - 4655.
Bioconcentration - Depuration - European eel - Geosmin - Off-flavour depuration
This study established that geosmin depuration from European eel is not affected by the water renewal rate of depuration tanks. A general fish bioaccumulation model extended with terms that account for effects of tank water renewal rate and system losses of chemicals, predicted strong effects of the water renewal rate of depuration tanks on geosmin depuration from European eel. Model predictions were validated in a depuration experiment with geosmin-loaded European eel (n = 95) with a mean (SD) individual weight of 134.4 (5.0) g and a mean (SD) lipid content of 33.7 (2.8) % (w/w). Fish were depurated for 24, 48 or 72 h at three different tank water renewal rates (0.3, 3.3 and 33 day-1). Treatments were installed by three different mean (SD) water flow rates (13.8 (1.3), 143.5 (9.2) and 1511 (80) L kg fish-1 day-1) over 30-L tanks. Eels eliminated geosmin from their bodies, but unlike the model predicted, this was independent of the water renewal rate of the depuration tanks. Although being eliminated from the fish, geosmin hardly appeared and certainly did not accumulate in the water of the depuration tanks as the model predicted. This observation may be explained by geosmin being eliminated from eel as metabolite rather than the parent compound. Geosmin elimination from eel seems not to occur according to the generally accepted passive diffusion mechanism for excretion of lipophilic chemicals, and geosmin biotransformation by the eel seems indicated. Clearly geosmin depuration from European eel cannot be enhanced by increasing water renewal rates of depuration tanks.
Hoe giftig zijn ammonia en nitraat voor snoekbaars?
Schram, E. ; Roques, J.A.C. ; Kuijk, T. van; Abbink, W. ; Heul, J.W. van der; Vries, P. de; Bierman, S.M. ; Vis, J.W. van de; Flik, G. - \ 2014
Aquacultuur 29 (2014)1. - ISSN 1382-2764 - p. 12 - 17.
snoekbaars - recirculatie aquacultuur systemen - aquacultuur - nitraat - ammoniak - voeropname - pike perch - recirculating aquaculture systems - aquaculture - nitrate - ammonia - feed intake
In intensieve recirculatiesystemen lopen vissen het risico blootgesteld te worden aan ammonia en nitraat. Hoe hoog mogen de nitraat- en ammoniaconcentratie zijn zonder dat dit negatieve effecten heeft op de vissen? IMARES onderzocht dit in samenwerking met de Radboud Universiteit Nijmegen en de Universiteit van Amsterdam voor juveniele snoekbaars. Conclusie: de ammonia (NH3) concentratie moet onder de 0.05 mg NH3-N/I gehouden worden. Van nitraat lijken juveniele snoekbaarzen zelfs bij 358 mg NO3-N/I nog weinig hinder te ondervinden.
The impact of elevated water ammonia and nitrate concentrations on physiology, growth and feed intake of pikeperch (Sander lucioperca)
Schram, E. ; Roques, J.A.C. ; Kuijk, T. van; Abbink, W. ; Heul, J.W. van der; Vries, P. de; Bierman, S.M. ; Vis, J.W. van de; Flik, G. - \ 2014
Aquaculture 420-421 (2014). - ISSN 0044-8486 - p. 95 - 104.
trout oncorhynchus-mykiss - acid-base regulation - early-life stages - rainbow-trout - salmo-gairdneri - recirculating aquaculture - scophthalmus-maximus - clarias-gariepinus - chronic toxicity - aquatic animals
The ammonia (NH3) and nitrate (NO3-) threshold concentrations in rearing water of juvenile pikeperch (Sander lucioperca) were assessed. Pikeperch with an initial mean (SD) weight of 17.7 (4.2) g were exposed to 0.9 (control), 3.6, 5.2, 7.1, 11.2 and 18.9 µM NH3 in the water for 42 days. Plasma NH4+ concentrations stayed at control levels (~ 650 µM) up to 11.2 µM NH3 in the water. At the highest water NH3 concentration tested, plasma NH4+ had more than doubled to 1400 µM. Based on the specific growth rate, the EC10 value for NH3 was 5.7 µM. When pikeperch (initial mean (SD) weight of 27.0 (4.9) g) were exposed to 0.1 (control), 1.5, 2.3, 3.7, 6.1, 10.2, 15.8 and 25.6 mM NO3- for 42 days, mean (SD) plasma NO3- concentrations increased linearly from 88 (47) to 5993 (899) µM at the highest ambient NO3- level. Feed intake, specific growth rate and feed conversion ratio were not affected. Neither NH3 nor NO3- exposure significantly affected haematocrit, plasma concentrations of cortisol, glucose, lactate, osmolality, gill morphology or branchial Na+/K+-ATPase activity in pikeperch. For juvenile pikeperch we advise not to exceed a water NH3 concentration of 3.4 µM (0.05 mg NH3–N/L), the lower limit of the 95% confidence interval of the EC10 value for SGR, to ensure proper physiology and growth. For NO3- we advise not to exceed 25 mM (350 mg NO3-–N/L). This criterion is based on the highest NO3- concentration tested (25.6 mM). As no negative effects were detected at the highest concentration tested, the actual NO3- threshold probably exceeds 25.6 mM.
Stress in African catfish (clarias gariepinus) following overland transportation
Manuel, R. ; Boerrigter, J. ; Roques, J. ; Heul, J.W. van der; Bos, R. van den; Flik, G. ; Vis, J.W. van de - \ 2014
Fish Physiology and Biochemistry 40 (2014)1. - ISSN 0920-1742 - p. 33 - 44.
oncorhynchus-mykiss walbaum - carp cyprinus-carpio - common carp - animal-welfare - rainbow-trout - responses - fish - l. - temperature - aggression
Of the many stressors in aquaculture, transportation of fish has remained poorly studied. The objective of this study was therefore to assess the effects of a (simulated) commercial transportation on stress physiology of market-size African catfish (Clarias gariepinus). Catfish weighing approximately 1.25 kg were returned to the farm after 3 h of truck-transportation, and stress-related parameters were measured for up to 72 h following return. Recovery from transportation was assessed through blood samples measuring plasma cortisol, glucose and non-esterified fatty acids (NEFA) and gill histology. Also, the number of skin lesions was compared before and after transport. Pre-transport handling and sorting elevated plasma cortisol levels compared to unhandled animals (before fasting). Plasma cortisol levels were further increased due to transportation. In control fish, plasma cortisol levels returned to baseline values within 6 h, whereas it took 48 h to reach baseline values in transported catfish. Plasma glucose and NEFA levels remained stable and were similar across all groups. Transported catfish did not, on average, have more skin lesions than the handling group, but the number of skin lesions had increased compared to unhandled animals. The macroscopic condition of the gills was similar in control, transported and unhandled catfish; however, light microscopy and immunohistochemistry revealed atypical morphology and chloride cell migration normally associated with adverse water conditions. From our data, we conclude that transportation may be considered a strong stressor to catfish that may add to other stressors and thus inflict upon the welfare of the fish.
Invloed van transport op de stressfysiologie van marktwaardige Afrikaanse meerval en Europese paling
Vis, J.W. van de; Schram, E. ; Boerrigter, J. ; Manuel, R. ; Heul, J.W. van der; Bos, R. van den; Hofman, A.R.T. ; Ros, N.A.M. ; Lambooij, E. ; Flik, G. - \ 2013
IJmuiden : IMARES Wageningen UR (Rapport / IMARES Wageningen UR C100/13) - 28
stressfysiologie - clarias gariepinus - european eels - transport - laesies - bloedplasma - visserij - dierenwelzijn - stress physiology - lesions - blood plasma - fisheries - animal welfare
Het onderzoek was gericht op effecten van praktijkgerichte transportcondities van marktwaardige Afrikaanse meerval (Clarias gariepinus) en Europese paling (Anguilla anguilla) op de relevante fysiologische parameters in het bloedplasma (cortisol, glucose en niet-veresterde vrije vetzuren) en mogelijke laesies van de huid.
Stress response in farmed African catfish, Clarias gariepinus and European eel, Anguilla anguilla, to overland transport
Vis, J.W. van de; Boerrigter, J. ; Heul, J.W. van der; Manuel, R. ; Roques, J. ; Bos, R. van den; Flik, G. - \ 2012
In: Proceedings of Aqua 2012 Global Aquaculture - securing our future, September 1-5th, Prague, Czech Republic. - Prague : - p. 1128 - 1128.
Welfare interventions in flatfish recirculation aquaculture systems and their economical implications
Schneider, O. ; Schram, E. ; Kals, J. ; Heul, J.W. van der; Kankainen, M. ; Mheen, H.W. van der - \ 2012
Aquaculture Economics & Management 16 (2012)4. - ISSN 1365-7305 - p. 399 - 413.
turbot scophthalmus-maximus - trout culture-system - juvenile turbot - water-quality - growth - ozonation
Integratie van een zeewierreactor in een marien recirculatiesysteem: effecten op vis en waterkwaliteit
Schram, E. ; Schelvis, R. ; Hinrichs, C.S. ; Heul, J.W. van der - \ 2012
IJmuiden : IMARES (Rapport / IMARES Wageningen UR C093/12) - 34
tarbot - visteelt - zeewieren - zeewierenteelt - recirculatie aquacultuur systemen - recirculatiesystemen - kwaliteit - waterkwaliteit - turbot - fish culture - seaweeds - seaweed culture - recirculating aquaculture systems - recirculating systems - quality - water quality
In opdracht van Hortimare BV en in het kader van het VIP project Vis, Schelp en Wier onderzocht IMARES de integratie van een zeewierreactor in een marien recirculatiesysteem (RAS) voor de kweek van tarbot. Onderzocht werden de effecten van de aanwezigheid van een zeewierreactor met Ulva in een marien RAS op de waterkwaliteit, de productie en gezondheid van tarbot, de kwaliteit van de vis als eindproduct en het functioneren van de zeewierreactor.
Shortlist masterplan wind Effect of pilling noise on the survival of fish larvae (pilot study)
Bolle, L.J. ; Jong, C.A.F. ; Bierman, S.M. ; Haan, D. de; Huijer, T. ; Kaptein, D. ; Lohman, M. ; Tribuhl, S.V. ; Beek, F.A. van; Damme, C.J.G. van; Berg, F. van den; Heul, J.W. van der; Keeken, O.A. van; Wessels, P. ; Winter, H.V. - \ 2011
IJmuiden : IMARES (Report / IMARES Wageningen UR C092/11) - 138
larven - vissen - geluidshinder - overleving - gezondheidsgevaren - diergezondheid - health impact assessment - noordzee - windmolenpark - larvae - fishes - noise pollution - survival - health hazards - animal health - north sea - wind farms
Fish can suffer lethal damage to their swim bladder or other organs due to loud impulse sounds such as pile driving noise. However, detailed dose-response studies are still scarce, especially for the early life stages. In view of the rapid extension of offshore wind farms in the North Sea, there is an urgent need to acquire more knowledge on the effects of noise caused by pile driving. This study focussed on the effect of piling noise on the survival of fish larvae.
Shortlist Masterplan Wind. Effect of pilling noise on the survival of fish larvae( pilot study) progress report
Bolle, L.J. ; Keeken, O.A. van; Damme, C.J.G. van; Winter, H.V. ; Haan, D. de; Lohman, M. ; Heul, J.W. van der; Huijer, T. - \ 2010
IJmuiden : IMARES (Report / IMARES Wageningen UR C176/10) - 76
larven - vissen - geluidshinder - overleving - diergezondheid - gezondheidsgevaren - health impact assessment - noordzee - windmolenpark - larvae - fishes - noise pollution - survival - animal health - health hazards - north sea - wind farms
Fish can suffer lethal damage to swimming bladder or other organs due to extreme loud impulse sounds caused by e.g. pile driving (Popper & Hastings 2009). Juvenile and adult fish can actively swim away from a sound source, but planktonic larvae are not able to do this. As a result, fish larvae may suffer more from underwater noise than the older life stages. Despite the many indications for adverse effects, detailed information on the effect of different sound levels on fish is still scarce, especially for the early life stages. Within the framework of the Appropriate Assessment of Dutch offshore wind farms, the effect of piling noise on the southern North Sea population of herring, sole, and plaice larvae was simulated (Prins et al. 2009). For this, an existing larval transport model (Bolle et al. 2005, 2009, Dickey-Collas et al. 2009, Erftemeijer et al. 2009) was expanded with crude assumptions on larval mortality caused by pile driving. The model results were extrapolated to other fish species and older life stages, based on “expertjudgment", in an attempt to assess the effect of offshore piling on the prey availability for birds and marine mammals in Natura 2000 areas (Bos et al. 2009). This assessment involved a large number of uncertainties. The first and most important uncertainty was the range around a piling site in which larval mortality occurs. It was assumed that 100% mortality occurs up to a distance of 1 km from the piling site. However, little is known about larval mortality rates in relation to the level of exposure to piling noise. In general, there is an urgent need to obtain more knowledge on the effect of sound on fish (survival, distribution, and behaviour) during different life stages. More particularly, in view of the rapid extension of offshore wind farms, there is an urgent need to fill the knowledge gap on lethal effects of loud impulse noises caused by pile driving. The broader aim of the current project is to examine the effect of piling noise on the survival of fish larvae. However, within the limited resources and time frame of the Shortlist research programme it is not possible to carry out field experiments, nor is it possible to execute elaborate series of experiments. The first goal within the Shortlist programme is to examine the feasibility of laboratory experiments with pile driving noise and fish larvae. The second goal is to use the laboratory set-up in a pilot study aiming at determining the threshold at which mortality of fish larvae occurs. This shortlist study is limited to laboratory experiments, lethal effects, larvae of 1 species (sole, Solea solea) and 3 series of experiments (trials). The study consists of exposure-effect experiments only; the effects of pile driving at the population level will not be modelled, nor will the results be extrapolated to other species or life stages. The progress to date has been documented in a series of memo’s. These memos are included in this report as Appendices and are summarised in the sections of the report.
The use of light traps in monitoring abundance of glass eel
Graaf, M. de; Heul, J.W. van der; Willigen, J.A. van; Leijzer, T.B. - \ 2010
IJmuiden : IMARES (Report / Wageningen IMARES C167/10) - 16
palingen - monitoring - methodologie - lichtvallen - evaluatie - eels - methodology - light traps - evaluation
Door de sterke afname van de glasaalintrek verkeert de jaarlijkse bemonstering in de problemen. De kosten van het huidige arbeidsintensieve kruisnetprogramma zijn hoog en de sterke afname van de glasaalvangsten brengen de statistische betrouwbaarheid in gevaar. De ontwikkeling van een nieuwe, betrouwbare en betaalbare methode om de jaarlijkse glasaalmonitoring uit te voeren is belangrijk voor het beheer van de in zorgwekkende toestand verkerende aalstand. In 2010 is er aanvullend onderzoek gedaan naar de mogelijkheid lichtvallen in te zetten als methodiek voor het monitoren van absolute dichtheden glasaal. Het onderzoek in 2010 heeft duidelijk aangetoond dat het twijfelachtig is of lichtvallen een goed alternatief zijn voor de huidige kruisnetbemonstering
Enrichment of the African catfish Clarias gariepinus (Burchell) with functional selenium originating from garlic: effect of enrichment period and depuration on total selenium level and sensory properties
Schram, E. ; Schelvis-Smit, A.A.M. ; Heul, J.W. van der; Luten, J.B. - \ 2010
Aquaculture Research 41 (2010)6. - ISSN 1355-557X - p. 793 - 803.
fatty-acid-composition - oil finishing diet - cancer prevention - fish-oil - speciation
We wanted to optimize the procedure for the selenium enrichment of farmed African catfish, using garlic as dietary selenium source. In the first experiment we established the relation between the length of the selenium enrichment period and the resulting total selenium level in the fillet of the fish. It was found that at a dietary level of 11.7 mg kg-1 Se, a total selenium level in the fillet of 0.7 mg kg-1 was reached in a relatively short enrichment period of 10 days before harvest. In the second experiment we studied the effect of depuration on the selenium level in the fillet and the sensory properties of selenium-enriched African catfish. It was found that total selenium levels in the fillet were not affected during a 7-day depuration period, while garlic odours and flavours in the raw and cooked fillets were significantly reduced after 2 days of depuration. We concluded that selenium enrichment of farmed African catfish can be obtained by selenium-enriched finishing diets, while garlic odours and flavours resulting from dietary garlic can be effectively reduced in the fillet during a short depuration period without negatively affecting fillet levels of total selenium.
Increased moisture of pelleted dry diets improves sole growth
Schneider, O. ; Heul, J.W. van der; Schram, E. ; Schrama, J.W. ; Saeter, B.S. - \ 2009
In: Proceedings of Aquaculture Europe 2009, Trondheim, Norway, 14 - 17 August, 2009. - Trondheim, Norway : European Aquaculture Society - p. 553 - 554.
The effects of pulse stimulation on biota - Research in relation to ICES advice - Effects on dogfish
Haan, D. de; Marlen, B. van; Velzeboer, I. ; Heul, J.W. van der; Vis, J.W. van de - \ 2009
IJmuiden : IMARES (Report / IMARES Wageningen UR C105/09) - 32
hondshaaien - dierenwelzijn - visserij - visserijbeheer - vis vangen - pulsvisserij - dogfishes - animal welfare - fisheries - fishery management - fishing - pulse trawling
Onderzoek naar het welzijn van hondshaaien bij de vangst. Er is onderzocht of de methode van het gebruik van stroom wel diervriendelijk is. De conclusie is dat dit geen beletsel voor de diervriendelijkheid oplevert
De relatie tussen waterkwaliteit en welzijn bij Afrikaanse meerval en tong op Nederlandse viskwekerijen
Abbink, W. ; Blanco Garcia, A. ; Heul, J.W. van der; Gool, A.C.M. van; Schram, E. ; Vis, J.W. van de - \ 2009
Yerseke : IMARES (Rapport / IMARES Wageningen UR nr. C109/09) - 39
waterkwaliteit - dierenwelzijn - viskwekerijen - clarias gariepinus - tong (vis) - visteelt - water quality - animal welfare - fish farms - dover soles - fish culture
Het doel van deze literatuurstudie is het beschrijven van de mogelijke knelpunten in de relatie tussen het welzijn van vissen en de waterkwaliteit in recirculatiesystemen (RAS), gespecificeerd op de Afrikaanse meerval (Clarias gariepinus) en tong (Solea solea). Hiernaast is bij een tongkwekerij en bij twee meervalkwekerijen een studie uitgevoerd naar de waterkwaliteit. De resultaten tonen aan dat de temperatuur, pH en zuurstofconcentratie van het water constant zijn. Het TAN-niveau (Total Ammonia Nitrogen) laat een variabel beeld zien bij de meervalkwekerijen, bij de tongkwekerij is het TAN-niveau constant laag.
Het ontwikkelen van een glasaalval ten behoeve van monitoring
Leijzer, T.B. ; Dijkman Dulkes, H.J.A. ; Heul, J.W. van der; Willigen, J.A. van - \ 2009
IJmuiden : IMARES (Rapport / Wageningen IMARES C069/09) - 19
palingen - vangmethoden - technieken - bemonsteren - monitoring - eels - trapping - techniques - sampling
Naar de intrek van glasaal wordt al sinds 1938 onderzoek gedaan, door middel van een kruisnet. Vanaf 1980 deed zich een snelle daling voor, waarna een periode begon met een heel lage intrek, die voortduurt tot op de dag van vandaag. In 2009 is besloten om te onderzoeken of er glasaalvallen ontwikkeld kunnen worden om de glasaalmonitoring met minder inspanning te kunnen uitvoeren. Hierbij is een viertal verschillende vallen getest. Dit zijn een hevel, een zoetwaterval en een zoutwaterval (beide gebaseerd op de werking van de hevel) en een lichtval. Indien een systeem langere tijd achter elkaar kan functioneren zonder dat onderzoekers aanwezig hoeven te zijn zou dit een goedkoop monitorings-programma mogelijk maken.
The Benefish consortium reports on the influence of system water refreshment rates on realized feed load, weight development, fish physiology and behaviour in turbot
Schram, E. ; Heul, J.W. van der; Vis, J.W. van de; Abbink, W. ; Jansen, J.M. ; Schneider, O. ; Blancheton, J.P. ; Person, J. - \ 2009
IJmuiden : IMARES (Report / Wageningen IMARES no. C034.09) - 21
visteelt - viskwekerijen - aquacultuur - waterkwaliteit - teeltsystemen - dierenwelzijn - dierfysiologie - voedingsgedrag - fish culture - fish farms - aquaculture - water quality - cropping systems - animal welfare - animal physiology - feeding behaviour
Farmers with recirculation aquaculture systems (RAS) have a greater necessity and capacity to control the culture conditions of their farms than farmers with other aquaculture systems. Water quality is one of the factors that is closely monitored and managed in order to maintain the optimal levels of oxygen, ammonia, temperature, pH, and CO2. Effects of these parameters on growth and health are well studied and almost immediately noticeable. In RAS it often occurs that, although water quality conditions seem to be optimal, the feed intake of the fish might suddenly diminishes, thus reflecting a situation of sub optimal welfare of the animals. This phenomenon is particular relevant in marine RAS where these situations of reduced feed intake occur even though the normally monitored water quality parameters and husbandry conditions appear to be optimal. Similar phenomena also occur in other aquaculture culture systems, such as flow through systems, where feed intake fluctuates whilst the reasons are not always known, although there is typically less control and monitoring compared with RAS. It is therefore necessary to actively monitor deviation of expected feed intake, in combination with the monitoring of culture conditions and farm management on pilot-scale level. Only through this intermediate level experimental work and farm observations for the assumed relationship between deviation of expected feed intake and fish welfare can be validated. It is furthermore necessary to provide refinements to causative relationships expected to be found on commercial farms, where it is often claimed that e.g. lower system water refreshment rates or more closed RAS are leading to growth retardation and lower feed intake in fish and thus lower production. The present study is, therefore, intending to prove the hypothesis that changes in feed intake can be associated with changed fish welfare status, using turbot as model species. It is furthermore hypothesized that this changed fish welfare status is caused by different system water refreshment rates and fish and system management. As a final result, feed intake should relate by same efficiency to lower fish growth in closed RAS compared to flow through systems. The objectives are therefore to validate the relationships between deviation from expected feed intake and fish welfare, and their causative factors on the commercial farms interpreting data on feed intake, behavior, endocrinology and immune patterns as welfare indicators.
Eindrapport LNV bestek Duurzame viskweek
Schram, E. ; Heul, J.W. van der; Vis, J.W. van de; Abbink, W. ; Jansen, J.M. ; Schneider, O. - \ 2009
IJmuiden & Yerseke : IMARES (Rapport / Wageningen IMARES C019.09) - 84
aquacultuur - visteelt - teeltsystemen - dierenwelzijn - dierfysiologie - hergebruik van water - aquaculture - fish culture - cropping systems - animal welfare - animal physiology - water reuse
In Nederland wordt vis vooral in recirculatiesystemen (RAS) gekweekt , hetgeen als één van de meest duurzame manieren van viskweek wordt beschouwd. Of deze systemen echter optimaal zijn voor het welzijn en de gezondheid van de vis is nog de vraag. Een verminderde groei in recirculatiesystemen ten opzichte van doorstroomsystemen wordt gemeld voor zeebaars in de literatuur en voor een aantal andere soorten vanuit de praktijk. Dit geeft aan dat de kweekomstandigheden in RAS niet altijd optimaal zijn. Het belangrijkste verschil tussen recirculatiesystemen en doorstroomsystemen is de mate waarin het kweekwater wordt vervangen door vers water. Als gevolg van hergebruik van kweekwater treedt accumulatie op van opgeloste en gesuspendeerde stoffen die in het kweeksysteem geïntroduceerd zijn of geproduceerd worden. De mate waarin accumulatie optreedt wordt bepaald door de mate van verversing van het kweekwater. De onderzoeksvragen waren daarom: wat is het effect van de mate van recirculatie van kweekwater op (1) het gedrag van vis, (2) de fysiologie van vis en (3) de groei van vis; (4) is groeiremming in RAS soortspecifiek en welk inzicht in groeiremming levert dit op en (5) wat is het effect van sorteren van vissen op niet gesorteerde vissen binnen hetzelfde RAS?
Electrical stunning of fish putting it into practice
Vis, J.W. van de; Burggraaf, D. ; Heul, J.W. van der; Pol-Hofstad, I. ; Lambooij, B. - \ 2008
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