Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

    Records 1 - 70 / 70

    • help
    • print

      Print search results

    • export

      Export search results

    Check title to add to marked list
    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 - clarias gariepinus - european eels - transport - 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 - health impact assessment - 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 - health impact assessment - 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 - monitoring - 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 - clarias gariepinus - 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 - monitoring
    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
    Startle response of captive North Sea fish species to underwater tones between 0.1 and 64 kHz
    Kastelein, R.A. ; Heul, S. van der; Verboom, W.C. ; Jennings, N. ; Veen, J. van der; Haan, D. de - \ 2008
    Marine Environmental Research 65 (2008)5. - ISSN 0141-1136 - p. 369 - 377.
    cod gadus-morhua - directional hearing - behavior - sound - thresholds - ultrasound - stimuli - noise - field
    World-wide, underwater background noise levels are increasing due to anthropogenic activities. Little is known about the effects of anthropogenic noise on marine fish, and information is needed to predict any negative effects. Behavioural startle response thresholds were determined for eight marine fish species, held in a large tank, to tones of 0.1-64 kHz. Response threshold levels varied per frequency within and between species. For sea bass, the 50% reaction threshold occurred for signals of 0.1-0.7 kHz, for thicklip mullet 0.4-0.7 kHz, for pout 0.1-0.25 kHz, for horse mackerel 0.1-2 kHz and for Atlantic herring 4 kHz. For cod, pollack and eel, no 50% reaction thresholds were reached. Reaction threshold levels increased from similar to 100 dB (re 1 mu Pa, rms) at 0.1 kHz to similar to 160 dB at 0.7 kHz. The 50% reaction thresholds did not run parallel to the hearing curves. This shows that fish species react very differently to sound, and that generalisations about the effects of sound on fish should be made with care. As well as on the spectrum and level of anthropogenic sounds, the reactions of fish probably depend on the context (e.g. location, temperature, physiological state, age, body size, and school size).
    Deliverable 2: Report on the production of GIF by turbot, the effects on growth performance of turbot of local GIF production within RAS and the presence of GIF at commercial farm level
    Schram, E. ; Heul, J.W. van der; Jol, J.G. ; Vincon, B. ; Bout, J. ; Cornelisse, J. - \ 2008
    IJmuiden : IMARES (Report / Wageningen IMARES C115/08) - 79
    visteelt - viskwekerijen - teeltsystemen - achterblijven in groei - groeieffecten - groeiremmers - tarbot - proeven - fish culture - fish farms - cropping systems - runting - growth effects - growth inhibitors - turbot - trials
    One of the working hypotheses of this project is that growth retardation of turbot cultured in recirculating aquaculture systems (RAS) is caused by the accumulation of growth inhibiting factors (GIF) produced by the turbot themselves in the culture water. Our first goal was to demonstrate the production of growth inhibiting factors by turbot following the methodology of Yurl and Perlmutter. A series of successive experiments was performed. Extracts from turbot culture water were tested for GIF presence in early life stage tests using eggs and larvae and small scale growth trials with juveniles. Our second goal was to demonstrate the transfer of GIF between tanks. Four experiments involving the integration of experimental tanks in a farm scale setting were performed. Our third goal was to demonstrate the presence of GIF at commercial farms. Two juvenile growth trials were performed.
    The influence of 70 and 120 kHz tonal signals on the behavior of harbor porpoises (Phocoena phocoena) in a floating pen
    Kastelein, R.A. ; Verboom, W.C. ; Jennings, N. ; Haan, D. de; Heul, S. van der - \ 2008
    Marine Environmental Research 66 (2008)3. - ISSN 0141-1136 - p. 319 - 326.
    gill-net fishery - acoustic alarms - perceived urgency - marine mammals - lower bay - bycatch - fundy - noise - echolocation
    Two harbor porpoises in a floating pen were subjected to five pure tone underwater signals of 70 or 120 kHz with different signal durations, amplitudes and duty cycles (% of time sound is produced). Some signals were continuous, others were intermittent (duty cycles varied between 8% and 100%). The effect of each signal was judged by comparing the animals¿ surfacing locations and number of surfacings (i.e. number of respirations) during test periods with those during baseline periods. In all cases, both porpoises moved away from the sound source, but the effect of the signals on respiration rates was negligible. Pulsed 70 kHz signals with a source level (SL) of 137 dB had a similar effect as a continuous 70 kHz signal with an SL of 148 dB (re 1 ¿Pa, rms). Also, a pulsed 70 kHz signal with an SL of 147 dB had a much stronger deterring effect than a continuous 70 kHz signal with a similar SL. For pulsed 70 kHz signals (2 s pulse duration, 4 s pulse interval, SL 147 dB re 1 ¿Pa, rms), the avoidance threshold sound pressure level (SPL), in the context of the present study, was estimated to be around 130 dB (re 1 ¿Pa, rms) for porpoise 064 and around 124 dB (re 1 ¿Pa, rms) for porpoise 047. This study shows that ultrasonic pingers (70 kHz) can deter harbor porpoises. Such ultrasonic pingers have the advantage that they do not have a ¿dinner bell¿ effect on pinnipeds, and probably have no, or less, effect on other marine fauna, which are often sensitive to low frequency sounds.
    Enrichment of African catfish with functional selenium originating from garlic
    Schram, E. ; Pedrero, Z. ; Camara, C. ; Heul, J.W. van der; Luten, J.B. - \ 2008
    Aquaculture Research 39 (2008)8. - ISSN 1355-557X - p. 850 - 860.
    rainbow-trout salmo - enzymatic probe sonication - cancer prevention - dietary selenium - tissue selenium - channel catfish - selenomethionine - speciation - gairdneri - requirement
    We wanted to create functional seafood with high concentrations of organic selenium (seleno-methyl-selenocysteine and ¿-glutamyl-seleno-methyl-selenocysteine) with anti-carcinogenic properties for human consumers. Garlic containing high concentrations of these organic selenium compounds was used as a selenium source in five experimental feeds for African catfish (1.9, 2.8, 3.9, 5.1 and 8.5 mg kg¿1 Se); a sixth experimental feed was formulated without garlic (1.9 mg kg¿1 Se). The experimental feeds were fed to African catfish [initial mean (SD) weight 100.7 (2.7) g] for 43 days with three replicates per treatment. Whole fish fillets were sampled for total selenium analysis (start and end) and selenium speciation (end). We found a positive linear relationship between dietary and fillet concentrations for total selenium and selenomethionine. The dietary total selenium concentration of 8.5 mg kg¿1 resulted in a total selenium concentration of 0.9 mg kg¿1 in the fillet (wet tissue). The majority of the selenium compounds recovered in an extract made from the fillet consisted of selenomethionine, considered to be important from a nutritional point of view. Seleno-methyl-selenocysteine, one of the organic selenium species to which superior anti-carcinogenic properties are attributed, was detected in the fillet but could not be quantified.
    Elektrisch bedwelmen van Afrikaanse meerval, paling en tilapia: van laboratorium naar de praktijk
    Vis, J.W. van de; Burggraaf, D. ; Heul, J.W. van der; Pol-Hofstede, I. ; Lambooij, B. - \ 2008
    Aquacultuur 23 (2008)2. - ISSN 1382-2764 - p. 25 - 29.
    aquacultuur - visserij - dierenwelzijn - bedwelmen - aquaculture - fisheries - animal welfare - stunning
    Methoden om op meer diervriendelijke wijze vissen te doden staan de laatste jaren meer en meer in de belangstelling.
    The effect of pulse stimulation on biota - Research in relation to ICES advice - progress report with preliminary results
    Marlen, B. van; Vis, J.W. van de; Haan, D. de; Burggraaf, D. ; Heul, J.W. van der; Terlouw, A. - \ 2007
    IJmuiden : IMARES (Report / Wageningen IMARES C098/07) - 24
    pulsatie - elektrische stimulatie - bodemfauna - vistuig - visserij - monitoring - diergezondheid - pulsvisserij - pulsation - electrical stimulation - soil fauna - fishing gear - fisheries - monitoring - animal health - pulse trawling
    In response to questions asked by ICES on the effects of pulse stimulation in commercial beam trawling on components of the marine ecosystem a number of preliminary studies were undertaken in the period between 31 May and 5 October 2007. These activities involved: 1. Measurements on the detailed stimulus applied in the pulse trawling system developed by the company Verburg-Holland Ltd., i.e. the amplitude, pulse width, rise and fall times, repetition rate and field strength along the electrodes. These measurements were done onboard of the commercial fishing vessel MFV “Lub Senior” (UK153), and in tank facilities of the manufacturer of the pulse beam trawl. 2. Simulation of this stimulus in the recirculated aquaculture system available at IMARES 3. Development of a protocol for keeping small-spotted catsharks alive and well, including dietary requirements. 4. The exposure of catsharks to a simulated pulse under laboratory conditions and observation of behaviour, including foraging, and monitoring mortality 5. Investigation of possible spinal damage of cod caught by a commercial vessel using pulse beam trawls by X-ray photography.
    Effects of acoustic alarms, designed to reduce small cetacean bycatch in gillnet fisheries, on the behaviour of North Sea fish species in a large tank
    Kastelein, R.A. ; Heul, S. van der; Veen, J. van der; Verboom, W.C. ; Jennings, N. ; Haan, D. de; Reijnders, P.J.H. - \ 2007
    Marine Environmental Research 64 (2007)2. - ISSN 0141-1136 - p. 160 - 180.
    porpoises phocoena-phocoena - cod gadus-morhua - geophysical survey device - rockfish sebastes - startle response - clupea-harengus - floating pen - sounds - hearing - ultrasound
    World-wide many cetaceans drown incidentally in fishing nets. To reduce the unwanted bycatch in gillnets, pingers (acoustic alarms) have been developed that are attached to the nets. In the European Union, pingers will be made compulsory in some areas in 2005 and in others in 2007. However, pingers may effect non-target marine fauna such as fish. Therefore in this study, the effects of seven commercially-available pingers on the behaviour of five North Sea fish species in a large tank were quantified. The species tested were: sea bass (Dicentrarchus labrax), pout (Trisopterus luscus), thicklip mullet (Chelon labrosus), herring (Clupea harengus), and cod (Gadus morhua). The fish were housed as single-species schools of 9¿13 individuals in a tank. The behaviour of fish in quiet periods was compared with their behaviour during periods with active pingers. The results varied both between pingers and between fish species. Sea bass decreased their speed in response to one pinger and swam closer to the surface in response to another. Thicklip mullet swam closer to the bottom in response to two pingers and increased their swimming speed in response to one pinger. Herring swam faster in response to one pinger, and pout and cod (close relatives) showed no behavioural responses to any of the pingers. Of the seven pingers tested, four elicited responses in at least one fish species, and three elicited no responses. Whether similar responses would be elicited in these fish species in the wild, and if so, whether such responses would influence the catch rate of fisheries, cannot be derived from the results of this study. However, the results indicate the need for field studies with pingers and fish. Based on the small number of fish species tested, the present study suggests that the higher the frequency of a pinger, the less likely it is to affect the behaviour of marine fish.
    Een verkenning naar de mogelijkheden voor opslag van levende wolhandkrab
    Leijzer, T.B. ; Schram, E. ; Heul, J.W. van der; Bult, T.P. - \ 2007
    IJmuiden : IMARES (Rapport / Wageningen IMARES nr. C089/07) - 29
    krabben (schaaldieren) - schaaldieren - marktverkenningen - marketing - bewaartijd - opslagkwaliteit - dierecologie - mortaliteit - nederland - marktanalyse - crabs - shellfish - market surveys - marketing - storage life - storage quality - animal ecology - mortality - netherlands - market analysis
    Optimization of Dover sole reproduction: Final report for task 1.2 Upscaling of sole fingerling production: Production of Dover sole eggs: SOLEMATES Q5CR-2002-71039
    Hong, Y. ; Kamstra, A. ; Schram, E. ; Heul, J.W. van der - \ 2006
    IJmuiden : RIVO (Report / RIVO-Netherlands Institute for Fisheries Research C001/06) - 25
    tong (vis) - broeddieren - visstand - visserij - dover soles - broodstock - fish stocks - fisheries
    Stocking density-dependent growth of Dover sole (Solea solea)
    Schram, E. ; Heul, J.W. van der; Kamstra, A. ; Verdegem, M.C.J. - \ 2006
    Aquaculture 252 (2006). - ISSN 0044-8486 - p. 339 - 347.
    stress-response - sparus-aurata - rainbow-trout - turbot - l.
    Dover sole were reared at 6 different stocking densities between 0.56 and 12.6 kg/m2 with duplicate tanks for each treatment. The experiment lasted for 55 days. Water quality effects on growth were minimised by making the flow rate per tank proportional to the feeding load. Individual initial and final weights were determined for all fishes to calculate the specific growth rate and the coefficient of variation within each culture tank. The specific growth rate of Dover sole significantly decreased with increasing stocking density. Mortality increased significantly with increasing stocking density. The difference between initial and final CV (¿CV) increased with stocking density (P <0.06). A significant relation between stocking density and productivity was found. Productivity peaked at a stocking density of 7.4 kg/m2. The underlying mechanisms causing reduced average individual growth with increasing stocking densities are still poorly understood. Therefore, systematic behavioural studies focusing on the mechanisms causing depressed growth with increasing stocking density are recommended for future research.
    Onderzoek naar de invloed van onderwatergeluid op vissoorten van de Noordzee : Reactions of North Sea fish species to underwater sounds in a wide frequency range
    Kastelein, R.A. ; Heul, S. van der; Verboom, W.C. ; Jennings, N. ; Veen, J. van der; Reijnders, P.J.H. - \ 2005
    Texel : Alterra - 24
    vissen - geluid - diergedrag - aquatisch milieu - effecten - noordzee - onderwaterakoestiek - fishes - noise - animal behaviour - aquatic environment - effects - north sea - underwater acoustics
    World-wide, underwater anthropogenic noise is increasing. To predict potential effects of man-made noise on marine fish, information is needed on the hearing sensitivity of fish for certain types of sounds. However, when a fish detects a sound, this does not mean that it will react to it. In most animals, sound needs to reach a certain sound pressure level before the behaviour of an animal is affected. In this study such threshold levels were attempted to be determined for eight fish species occurring in the North Sea: sea bass (Dicentrarchus labrax), thicklip mullet (Chelon labrosus), pout (Trisopterus luscus), cod (Gadus morhua), eel (Anguilla anguilla), pollack (Pollachius pollachius), horse mackerel (Trachurus trachurus) and Atlantic herring (Clupea harengus).
    A comparison of the growth potential of Dover sole (Solea solea) and Senegal sole (Solea senegalensis) under intensive rearing conditions
    Schram, E. ; Heul, J.W. van der; Kamstra, A. ; Hong, Y. - \ 2005
    IJmuiden : RIVO (Report / RIVO C081/05) - 27
    tong (vis) - solea - visteelt - dover soles - solea - fish culture
    This trial was set up to compare the growth performance of Dover sole and Senegal sole under intensive rearing conditions.
    Gonad Development of male Sole, S. solea (L.), in natural and culture conditions between March and June 2003 in relation to environmental factors
    Blonk, R.J.W. ; Hong, Y. ; Kamstra, A. ; Schram, E. ; Heul, J.W. van der - \ 2005
    IJmuiden : RIVO (Report / RIVO C080/05) - 44
    zolen - soleidae - tong (vis) - spermatogenese - aquacultuur - wilde dieren - vangen van dieren - vergelijkend onderzoek - soles - soleidae - dover soles - spermatogenesis - aquaculture - wild animals - capture of animals - comparative research
    The aim of the present study was to detect differences of spermatogenesis between wild, captured and reared (F1) sole (Solea solea L.) broodstock. Differences between sampling months March and June 2003 as well as differences between groups were determined.
    Development of functional seafood products through dietary modulations in aquaculture: enrichment of african catfish with functional selenium: dose response relation and growth performance
    Schram, E. ; Heul, J.W. van der; Luten, J.B. - \ 2005
    In: Abstracts of the 35th WEFTA meeting, Antwerp, 19-22-September 2005. - Antwerp : WEFTA - p. 58 - 58.
    Task 3.3 Use of circular tanks for on growing of Dover sole
    Mheen, H.W. van der; Schram, E. ; Kloet, C.J. ; Heul, J.W. van der; Kamstra, A. - \ 2004
    IJmuiden : RIVO (Report / RIVO-Netherlands Institute for Fisheries Research C077/04) - 24
    tong (vis) - aquacultuur - visteelt - tanks - ontwerp - knoopwerk - dekking - substraten - dover soles - aquaculture - fish culture - tanks - design - netting - coverage - substrates
    Circular tanks are widely used in aquaculture. They have the advantage of being self-cleaning, which is important for all forms of aquaculture. They also have a constant and non-ending flow throughout the tank, which is a particular advantage for active swimming fish species. The use of circular tanks in sole production is not widely known. Sole is not an active swimming species; therefore a non-ending flow is probably not necessary. However, the self-cleaning aspect of circular tanks is still a great advantage. Therefore the objective of this study was to optimize the production of sole in circular tanks.
    Comparison of the performance of six artificial feeds for Dover sole (Solea solea)
    Schram, E. ; Vin, C.M. de; Heul, J.W. van der; Kloosterboer, R.J. - \ 2003
    IJmuiden : RIVO (RIVO report C045/03) - 21
    tong (vis) - visvoeding - visteelt - synthetische diëten - dover soles - fish feeding - fish culture - synthetic diets
    This document reports the performance of six artificial diets for Dover sole, which has been assessed in a feeding trial. The feeding trial had two contractors: Nutreco and Solea bv. As a result some of the diets in the experiment will be kept anonymous to each of the contractors. This report has been written for Nutreco. It is concluded that among the Nutreco feeds none of the feeds yields better performance in terms of SGR and FCR than any of the other Nutreco feeds.
    Density dependent growth in dover sole (Solea solea)
    Schram, E. ; Kamstra, A. ; Heul, J.W. v.d. - \ 2002
    In: Seafarming : today and tomorrow : Aquaculture Europe 2002, Triestem 2002 / B. Basurco and M. Saroglia. - [S.l.] : European Aquaculture Society, 2002. - (Special publication ; 32) - p. 468 - 469.
    Bosreservaat De Heul : bosstructuur en vegetatie bij aanwijzing tot bosreservaat
    Clerkx, A.P.P.M. - \ 2001
    Wageningen : Alterra (Alterra-rapport 371) - 48
    bossen - vegetatie - beschermde bossen - bosecologie - nederland - utrecht - forests - vegetation - reserved forests - forest ecology - netherlands - utrecht
    ?Bosreservaat De Heul is in 1998 aangewezen als bosreservaat. Het bestaat uit grove dennen, douglas, Japanse lariks en Oostenrijkse den. In het grove-dennenbos heeft zich een struiklaag van sporkehout, lijsterbes, berk, zomereik en grove den ontwikkeld. De kruidlaag bestaat uit bochtige smele met pijpenstrootje, brede stekelvaren of blauwe bosbes.
    De bodemgesteldheid van bosreservaten in Nederland; deel 1 bosreservaat De Heul
    Mekkink, P. - \ 2000
    Wageningen : Alterra (Alterra-rapport 60.1) - 50
    bossen - bosgronden - humus - bodemkarteringen - bodemprofielen - beschermde bossen - natuurreservaten - grondwater - kaarten - nederland - utrecht - forests - forest soils - humus - soil surveys - soil profiles - reserved forests - nature reserves - groundwater - maps - netherlands - utrecht
    In bosreservaat De Heul komen pleistocene afzettingen uit de Formatie van Twente en de Formatie van Kootwijk aan de oppervlakte voor. Het zijn zandgronden en moerige gronden met daarin haarpodzolgronden, veldpodzolgronden, moerpodzolgronden, duin- en vlakvaaggronden. De gronden hebben grondwatertrap IIIa, IIIb, Vbo, VIo, VId, VIId en VIIId. De verbreiding van de geologische afzettingen is weergegeven op de geologische kaart. De verbreiding van de bodemeenheden en grondwatertrappen is weergegeven op de bodem- en grondwatertrappenkaart. Mede onder invloed van het opstandstype en het gevoerde beheer hebben zich humusprofielen ontwikkeld bestaande uit een ectorganisch en een endorganisch deel. De profielopbouw en de opbouw van de strooisellaag zijn beschreven en op tape vastgelegd.
    Experimental research on a novel oxygenation system for fish farms
    Kamstra, A. ; Heul, J.W. van der - \ 1999
    Unknown Publisher (REPORT C015/99)
    Een vergelijking van een aantal commercoele palingvoeders (situatie najaar 1998)
    Heul, J.W. van der; Kamstra, A. - \ 1998
    Unknown Publisher (RAPPORT C068/98)
    Onderzoek naar grondsmaak bij Afrikaanse meerval met behulp van een 'Electronic nose'
    Kamstra, A. ; Heul, J.W. van der; Scheerman, P. - \ 1998
    ijmuiden [etc.] : RIVO - 15
    clarias gariepinus - smaak - smaakonderzoek - clarias gariepinus - taste - taste research
    Performance and optimisation of trickling filters on eel farms
    Kamstra, A. ; Heul, J.W. van der; Nijhof, M. - \ 1998
    Aquacultural Engineering 17 (1998). - ISSN 0144-8609 - p. 175 - 192.
    The design of trickling filters used on commercial eel farms differs considerably with respect to dimensions, hydraulic and substrate loads and filter medium applied. In this paper, a model, developed for ammonium removal in a pilot-scale trickling filter, has been validated for a range of full-scale trickling filters, incorporating the above mentioned aspects. The performance of trickling filters was assessed at 14 commercial eel farms in The Netherlands. Analysis of the data obtained has shown that the model sufficiently explains and predicts the ammonium removal rate of a wide range of commercial trickling filters. The model is used to optimise performance of existing biofilters in terms of ammonium levels achieved and pumping costs. Observations have also been made on nitrite in recirculation systems. Concentrations of nitrite and the ratio between nitrite and ammonium vary widely in and between systems. The nitrite oxidation capacity in biofilms seems to be variable and sensitive to environmental disturbances.
    Effecten van denitrificatie en verversing op voederopname en voederbenutting van paling
    Kamstra, A. ; Heul, J.W. van der; Bouwman, K. - \ 1998
    Unknown Publisher (RAPPORT C039/98)
    Effecten van pH op voedselopname en voedselbenutting van Europese aal (Anguilla anguilla L.)
    Kamstra, A. ; Heul, J.W. van der; Bouwman, K. - \ 1998
    Unknown Publisher (RAPPORT C027/98)
    Nabehandeling van afvalwater uit viskwekerijen; een inventarisatie
    Kamstra, A. ; Heul, J.W. van der - \ 1998
    Unknown Publisher (RAPPORT C067/98)
    Een vergelijking van zes commerciële afmestvoeders voor Afrikaanse meerval
    Kamstra, A. ; Heul, J.W. van der - \ 1998
    Unknown Publisher (RAPPORT C053/98)
    Onderzoek naar de behandeling van afvalwater van een palingkwekerij. (tussenrapportage)
    Kamstra, A. ; Heul, J.W. van der - \ 1998
    Unknown Publisher (RAPPORT C019/98)
    A test of grower feeds for carp
    Kamstra, A. ; Heul, J. van der; Bouwman, K. - \ 1998
    Unknown Publisher (REPORT C037/98)
    Waterkwaliteitsmetingen meervalkwekerij Lamoree
    Heul, J.W. van; Kamstra, A. - \ 1997
    Unknown Publisher (RIVO-DLO Rapport C031/97)
    Een vergelijking van zes experimentele palingvoeders
    Heul, J.W. van der; Kamstra, A. - \ 1997
    Unknown Publisher (RIVO-DLO Rapport C032/97)
    Ontwerp van een productiesysteem voor paling in vijvers
    Kamstra, A. ; Heul, J.W. van der - \ 1997
    Unknown Publisher (RIVO-DLO Rapport C010/97)
    Een vergelijking van zes commerciële afmestvoeders voor Afrikaanse meerval
    Kamstra, A. ; Heul, J.W. van der - \ 1997
    Unknown Publisher (RIVO-DLO Rapport C003/97)
    Rapport inventarisatie van visziekten in Nederland 1985 - 1995
    Haenen, O.L.M. ; Kamstra, A. ; Heul, J.W. van der - \ 1996
    Lelystad : ID-DLO (Rapport / ID-Lelystad 96.003) - 31 p.
    Analyse van technische resultaten van een aantal palingkwekerijen over de periode 1994 en 1995
    Heul, J.W. van der; Kamstra, A. - \ 1996
    Unknown Publisher (RIVO-DLO RAPPORT C030/96)
    Afvalwater van viskwekerijen een inventarisatie en aanzet voor oplossingen
    Kamstra, A. ; Heeswijk, R. van; Heul, J.W. van der - \ 1996
    Unknown Publisher (RIVO-DLO RAPPORT C041/96)
    An evaluation of a new biofilter medium
    Kamstra, A. ; Heul, J.W. van der - \ 1996
    Unknown Publisher (RIVO-DLO Report C051/96)
    Waterbehandeling met ozon in de palingteelt: een praktijk-experiment
    Kamstra, A. ; Heul, J.W. van der - \ 1996
    Unknown Publisher (RIVO-DLO RAPPORT C024/96)
    Residuen van diergeneesmiddelen in kweekvis: literatuur-onderzoek en analyse van praktijkbemonsteringen
    Kamstra, A. ; Heul, J.W. van der; Haenen, O.L.M. ; Keukens, H.J. ; Mengelers, M.J.B. - \ 1995
    IJmuiden etc. : RIVO (RIVO rapport nr. C034/95) - 30
    Opkweek van glasaal
    Kamstra, A. ; Heul, J.W. van der - \ 1993
    IJmuiden : RIVO (Rapport / Rijksinstituut voor Visserijonderzoek 93.022) - 56
    Bedrijfsresultaten met de opkweek van glasaal : een vergelijking van teeltstrategieen
    Heul, J.W. van der - \ 1992
    IJmuiden : RIVO (Rapport / Rijksinstituut voor Visserijonderzoek, Afdeling Aquacultuur AQ 92-07) - 43
    Invloed van vangstlocatie en behandeling op groei en overleving van glasaal
    Heul, J.W. van der - \ 1991
    IJmuiden : RIVO (Rapport / Rijksinstituut voor Visserijonderzoek, Afdeling Aquacultuur AQ 91-07) - 16
    Metingen aan waterkwaliteit, vuilproduktie en vuilverwijdering in een semi-praktijksysteem voor palingteelt
    Kamstra, A. ; Heul, J.W. van der; Kesteloo - Hendrikse, J.J. - \ 1990
    IJmuiden : RIVO (Rapport / Rijksinstituut voor Visserijonderzoek, Afdeling Aquakultuur AQ 90-10) - 25
    palingen - visteelt - vissen - zoet water - industrieel afval - industrie - rioolwater - afvalwater - waterverontreiniging - waterzuivering - eels - fish culture - fishes - fresh water - industrial wastes - industry - sewage - waste water - water pollution - water treatment
    Een vergelijking tussen een aantal startvoeders en voederstrategieen voor de opkweek van glasaal
    Heul, J.W. van der; Kamstra, A. - \ 1990
    IJmuiden : RIVO (Rapport / Rijksinstituut voor Visserijonderzoek, Afdeling Aquacultuur AQ 90-09) - 12
    Groeivariatie bij aal : effecten van sorteren, dichtheid en isolatie
    Kamstra, A. ; Heul, J.W. van der - \ 1990
    IJmuiden : RIVO (Rapport / Rijksinstituut voor Visserijonderzoek, Afdeling Aquakultuur AQ 90-07) - 38
    Resultaten met een aantal commerciele startvoeders en voederstrategien voor glasaal
    Kamstra, A. ; Heul, J.W. van der - \ 1989
    IJmuiden : R.I.V.O. (Rapport / Rijksinstituut voor Visserijonderzoek AQ 89-06) - 10
    palingen - voer - visteelt - vissen - eels - feeds - fish culture - fishes
    Effect van sorteren en aantal voerplekken op groei en spreiding van groei bij aal (Anguilla anguilla)
    Heul, J.W. van der - \ 1989
    IJmuiden : R.I.V.O. (Rapport / Rijksinstituut voor Visserijonderzoek AQ 89-05) - 13
    palingen - voedingsrantsoenen - voedingsnormen - visteelt - vissen - eels - feed rations - feeding standards - fish culture - fishes
    Effekt van attractanten, voederniveau en korrelgrootte op acceptatie van droogvoer door glasaal (Anguilla anguilla (L))
    Kamstra, A. ; Heul, J.W. van der - \ 1988
    IJmuiden : R.I.V.O. (Rapport / Rijksinstituut voor Visserijonderzoek AQ 88-06) - 17
    palingen - voer - visteelt - vissen - eels - feeds - fish culture - fishes
    Aan de hand van de resultaten worden aanbevelingen gedaan voor de te volgen strategie in de eerste teeltfase van glasaal. De toevoeging van attractanten bestond uit een mengsel van de aminozuren alanine, glycine, histonine en proline
    Effect van enkele voersoorten en voedermethodieken op groei en mortaliteit van glasaal (Anguilla anguilla L.) in de eerste teeltfase
    Kamstra, A. ; Heul, J.W. van der - \ 1987
    IJmuiden : RIVO (Rapport / Rijksinstituut voor Visserijonderzoek BV 87-05)
    palingen - visteelt - visvoeding - vissen - eels - fish culture - fish feeding - fishes
    Bodemsamenstelling en bodemorganismen bij en in zandwinputten in het IJsselmeer
    v.d Heul, J.W. ; Cazemier, W.G. - \ 1980
    IJmuiden : Rijksinstituut voor Visserijonderzoek (Rapport / Biologisch onderzoek zoetwatervisserij - schubvis no. ZS 80-02) - 19
    Check title to add to marked list

    Show 20 50 100 records per page

    Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.