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.

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The fish egg microbiome : diversity and activity against the oomycete pathogen Saprolegnia
Liu, Y. - \ 2016
Wageningen University. Promotor(en): Francine Govers; Jos Raaijmakers, co-promotor(en): Irene de Bruijn. - Wageningen : Wageningen University - ISBN 9789462577671 - 169
salmon - fish eggs - marine microorganisms - microbial diversity - bioinformatics - genomics - saprolegnia - oomycota - fish diseases - suppression - fungal antagonists - zalm - visseneieren - mariene micro-organismen - microbiële diversiteit - bio-informatica - genomica - saprolegnia - oömycota - visziekten - onderdrukking - schimmelantagonisten

Y. Liu

Prof. dr. F. Govers (promotor); Prof. dr. J.M. Raaijmakers (promotor); Dr. I. de Bruijn (co-promotor); Wageningen University, 13 June 2016, 170 pp.

The fish egg microbiome: diversity and activity against the oomycete pathogen Saprolegnia

Emerging oomycete pathogens increasingly threaten biodiversity and food security. This thesis describes the study of the microbiome of Atlantic salmon (Salmo salar L.) eggs and analyses of the effects of infections by the oomycete pathogen Saprolegnia on the microbial architecture. A low incidence of Saprolegniosis was correlated with a relatively high abundance and richness of specific commensal Actinobacteria. Among the bacterial community, the isolates Frondihabitans sp. 762G35 (Microbacteriaceae) and Pseudomonas sp. H6 significantly inhibited hyphal attachment of Saprolegnia diclina to live salmon eggs. Chemical profiling showed that these two isolates produce furancarboxylic acid-derived metabolites and a lipopeptide viscosin-like biosurfactant, respectively, which inhibited hyphal growth of S. diclina in vitro. Among the fungal community, the fungal isolates obtained from salmon eggs were closely related to Microdochium lycopodinum/Microdochium phragmitis and Trichoderma viride. Both a quantitative and qualitative difference in the Trichoderma population between Saprolegnia-infected and healthy salmon eggs was observed, which suggested that mycoparasitic Trichoderma species could play a role in Saprolegnia suppression in aquaculture. This research provides a scientific framework for studying the diversity and dynamics of microbial communities to mitigate emerging diseases. The Frondihabitans, Pseudomonas and Trichoderma isolates, and/or their bioactive metabolites, are proposed as effective candidates to control Saprolegniosis.

Salmon tracing: Genotyping to trace back escapees from salmon aquaculture
Blonk, R.J.W. - \ 2014
Yerseke : IMARES (Report / IMARES Wageningen UR C029/14) - 15
zalm - zalmteelt - aquacultuur - genetische merkers - genotyping - salmon - salmon culture - aquaculture - genetic markers
The overall objective of the project is to assign an escaped salmon back to the farm responsible for the escape with near 100% accuracy. In this report, the potential of a set of genetic markers to assign an escaped salmon was determined for a set of 12 polymorphic microsatellite markers, provided by Nofima, and by using stochastic simulation. Also, the effect of different numbers of sires, and the effect of pooling of multiple sires in crosses was determined.
Genetisch gemanipuleerde zalm stap dichter bij supermarktschap
Heijden, P.G.M. van der - \ 2013
Aquacultuur 28 (2013)1. - ISSN 1382-2764 - p. 6 - 7.
zalm - kweekvis - visteelt - genetische modificatie - genetisch gemanipuleerde organismen - volksgezondheid - salmon - farmed fish - fish culture - genetic engineering - genetically engineered organisms - public health
In augustus 2010 oordeelde de Amerikaanse Food and Drug Administration (FDA) dat zij in de genetisch gemodificeerde (GM) zalm van het berdijf Aquabounty geen gevaren voor de menselijke gezondheid zag. Vlak voor Kerstmis 2012 werd een voorlopig rapport openbaar gemaakt waarin de toets van de zalm van Aquabounty op mogelijke milieueffecten werd beschreven. het rapport omschreef deze effecten als verwaarloosbaar. Nu de GM zalm ook deze toets met succes lijkt te gaan doorstaan, is de afstand tot kweek en verkoop in de winkel weer een stuk kleiner geworden.
Smolts van Roer naar Rotterdam : passage van jonge zalmen langs de ECI waterkrachtcentrale in Roermond
Roessink, I. ; Ottburg, F.G.W.A. - \ 2013
Wagenigen : Wageningen UR, Wetenschapswinkel (Alterra-rapport 2430) - ISBN 9789461731821 - 44
vismigratie - zalm - visziekten - schimmels - saprolegnia parasitica - monitoring - tellingen - energiecentrales - waterkracht - maas - midden-limburg - fish migration - salmon - fish diseases - fungi - censuses - power industry - water power - river meuse
Al jarenlang zetten vrijwilligers van VBC Roerdal en Arbeitsgemeinschaft Lachs und Meerforelle 2020 (ArGe Lachs) zich in voor de herintroductie van zalm op de rivier de Roer. Hierbij worden jonge zalmen uit ei opgekweekt en uitgezet in de bovenloop van de Roer. De vrijwilligers hebben echter tot nu toe geen zicht op de daadwerkelijke aantallen smolts (jonge zalmen) die, vanaf deze bovenstroomse delen, naar de Maas en daarmee uiteindelijk naar zee trekken. De smolts kunnen dit namelijk op vier manieren doen, via de smoltval, de aalpijp (aalfuik), de vispassage van de ECI waterkrachtcentrale of via de vispassage van de Hambeek. Verder worden er tijdens, delen van, de migratieperiode met schimmel geïnfecteerde jonge zalmen aangetroffen en is het niet duidelijk waardoor dit veroorzaakt wordt. In de Roer worden ook nog de nodige exotische rivierkreeften en wolhandkrabben gevangen, die mogelijk een bron van infecties zijn. In deze studie werden twee onderzoeksvragen beantwoord, ten eerste of de schimmels die op sommige smolts werden waargenomen wellicht door de toenemende aanwezigheid van exotische kreeften en krabben veroorzaakt kon worden en ten tweede welk deel van het totale aantal passerende smolts in de smoltval van de ECI centrale gemonitord werden tijdens hun trek naar zee.
Proficiency test for paracitides in salmon muscle
Elbers, I.J.W. - \ 2012
Wageningen : RIKILT Wageningen UR (Report / RIKILT 2012.018) - 54
zalm - spieren - antiparasitica - voedselveiligheid - analytische methoden - laboratoriumproeven - salmon - muscles - antiparasitic agents - food safety - analytical methods - laboratory tests
The aim of this proficiency study was to give laboratories the possibility to evaluate or demonstrate their competence for the analysis of parasiticides in salmon muscle. This study also provided an evaluation of the methods applied for the quantitative analysis of parasiticides in salmon muscle.
Deelproject 1: Nader identificeren van indicatoren, databronnen en problemen en mogelijkheden van integratie in ERDSS Technisch rapport
Schelvis-Smit, A.A.M. - \ 2010
IJmuiden : IMARES (Rapport / IMARES Wageningen UR C124/10) - 39
voedselveiligheid - zalm - risicoschatting - risicovermindering - risicofactoren - deskundigen - beleidsondersteuning - food safety - salmon - risk assessment - risk reduction - risk factors - experts - policy support
In het beleidsondersteunend project BO “Emerging Risk in de Nederlandes Voedselketen”is een prototype voor een systeem ontwikkeld voor het vroegtijdig identificeren van voedselveiligheidsrisico’s (Emerging Risk Detection Support System (ERDSS)). Dit systeem is ontwikkeld voor de zalmproductieketen en combineert expertkennis en informatie uit openbare databronnen om voedselveiligheidsrisico’s te identificeren.
Freedom Food : op de bres voor het welzijn van landbouwhuisdieren in het Verenigd Koninkrijk
Waller, B. ; Heijden, P.G.M. van der - \ 2009
Aquacultuur 24 (2009)1. - ISSN 1382-2764 - p. 32 - 33.
aquacultuur - dierhouderij - dierenwelzijn - viskwekerijen - visserij - visteelt - zalm - dierenbescherming - aquaculture - animal husbandry - animal welfare - fish farms - fisheries - fish culture - salmon - animal protection
Op 11 december 2008 gaf Bob Waller tijdens de NGVA thema-avond een presentatie met als titel "Fork naar Farm; Maatschappelijke visies op aquacultuur". Freedom Food is een organisatie die tot doel heeft het welzijnprogramma van het Royal Society for the Prevention of Cruelty to Animals - (RSPCA), de Britse Dierenbescherming voor landbouwhuisdieren vorm te geven
Emerging Risks in the Dutch Food Chain report on project 2: Application of indicator analyses on several critical points in the salmon production chain and identification of related data sources
Schelvis-Smit, A.A.M. ; Poelman, M. ; Schneider, O. - \ 2008
Yerseke : IMARES (Report / Wageningen IMARES C071/08) - 17
voedselveiligheid - zalm - risicoschatting - risicovermindering - risicofactoren - indicatoren - food safety - salmon - risk assessment - risk reduction - risk factors - indicators
An indicator analysis was performed on the fish production chain by assessing the indicators which may be of importance for the detection of emerging risks. The indicators were embedded in a “risk pathway”, in which the relations between different indicators could be illustrated. The risk pathways illustrate the main characteristics of the salmon production chain. However further research is required in order to develop further interaction with other sectors, and production chains to bring emerging risk detection to the next level. In relation to the assigned indicators, a selection of (electronic) data sources were identified in order to be able to combine data flows with indicators and risk pathways. The indicators were analyzed for availability, sources of data entry, validation of data sources, update frequency and delay in input. The combination of risk pathways, indicators and data sources, will be one of the key information sources for the further development of an Emerging Risk Detection Support System (ERDSS).
Ontwikkeling van een emerging risks identificatie systeem : (resultaten 2006 en vervolgactiviteiten in 2007)
Roest, J.G. van der; Marvin, H.J.P. - \ 2008
Wageningen : RIKILT, Instituut voor Voedselveiligheid (Rapport / RIKILT, Instituut voor Voedselveiligheid 2008.105) - 13
voedselveiligheid - risicoschatting - risicofactoren - visverwerkende industrie - visverwerking - zalm - food safety - risk assessment - risk factors - fish industry - fish processing - salmon
Het beleid (Ministerie van LNV) heeft de wens geuit om vroegtijdig nieuwe problemen van voedselveiligheid te kunnen signaleren. Het huidige (4-jarige) Emerging Risks-onderzoek binnen het BO-programma maakt daar onderdeel van uit. In het jaar 2006 is een verdieping verricht naar indicatoren die van belang zijn voor identificatie van potentiële nieuwe en onvoorziene risico’s waarbij de visproductieketen en in het bijzonder de zalmproductieketen als voorbeeld is genomen. Daarnaast is tijdens een mini-conferentie de mening gepeild van en kennis uitgewisseld met experts over early warning systems afkomstig uit Nederland (RIKILT, VWA, RIVM, LEI, AFSG en TNO) en uit het buitenland (DEFRA (UK), EFSA (Italië), ECDC (Zweden) en FAO (Italië). Hierbij is ook gediscussieerd over de rol van de stakeholders en hun percepties met betrekking tot emerging risks. Dit rapport geeft een overzicht van de resultaten van het onderzoek uit 2006 en geeft daarnaast inzicht in de vervolgactiviteiten die in 2007 zijn uitgevoerd
Bijvangsten van salmoniden en overige trekvissen vanuit een populatieperspectief
Jansen, H.M. ; Winter, H.V. ; Tulp, I.Y.M. ; Bult, T.P. ; Hal, R. van; Bosveld, J. ; Vonk, R. - \ 2008
IJmuiden : IMARES (Rapport / Wageningen IMARES C039/08) - 175
zalm - salmonidae - visserij - populatie-aanwas - herstel - belemmeringen - bijvangst - salmon - fisheries - recruitment - rehabilitation - disincentives - bycatch
De huidige studie gaat in op de vraag of de huidige visserijinspanning door bijvangsten het herstel van de zalmpopulatie in de weg staat. De voorliggende rapportage geeft een overzicht van een inventarisatie van bijvangsten van salmoniden en overige trekvissen in zowel de commerciële als de recreatieve visserij in de Nederlandse wateren. Visserijsterfte en overige sterftefactoren worden vervolgens afgezet tegen een populatieschatting waardoor de relatieve impact van visserij in perspectief geplaatst kan worden.
Options for pro-actively identifying emerging risk in the fish production chain
Roest, J.G. van der; Kleter, G.A. ; Marvin, H.J.P. ; Vos, B.I. de; Hurkens, R.R.C.M. ; Schelvis-Smit, A.A.M. ; Booij, K. - \ 2007
Wageningen : Rikilt - Institute of Food Safety (Report / RIKILT, Institute of Food Safety 2007.006) - 87
zalm - zalmteelt - risicoschatting - voedselveiligheid - voer - ketenmanagement - salmon - salmon culture - risk assessment - food safety - feeds - supply chain management
Jaarrapportage Passieve Vismonitoring Zoete Rijkswateren: fuik- en zalmsteekregistraties in 2004
Winter, H.V. ; Boois, I.J. de; Wiegerinck, J.A.M. ; Westerink, H.J. - \ 2005
IJmuiden : RIVO (Rapport / Nederlands Instituut voor Visserij Onderzoek (RIVO) C036/05) - 47
visserij - visserijbeheer - visbestand - monitoring - palingen - zalm - zoet water - vangstsamenstelling - visstand - nederlandse wateren - fisheries - fishery management - fishery resources - eels - salmon - fresh water - catch composition - fish stocks - dutch waters
In de zoete rijkswateren wordt op een 29-tal locaties van de commerciële fuikenvisserij op paling door beroepsvissers een vangstregistratie bijgehouden over het gehele seizoen (april-november). Ook van de andere bijgevangen vissoorten worden de aantallen en lengtes bepaald. Deze monitoring wordt vanaf 1993 uitgevoerd. Een ander onderdeel binnen de passieve monitoring is de zalmsteekregistratie. Hierbij worden op vier locaties in de Rijn en Maas met traditionele grofmazige fuiken (zalmsteken) gedurende twee perioden van zes weken in zomer en herfst gericht gevist op riviertrekvissen als zalm en zeeforel. Deze monitoring wordt vanaf 1994 uitgevoerd. Tezamen vormen deze de ‘passieve vismonitoring zoete rijkswateren’, die in opdracht van het Ministerie van Verkeer en Waterstaat, RIZA wordt uitgevoerd om trends en ontwikkelingen in de visstand te volgen ten behoeve van beheers- en beleidsontwikkeling en evaluatie van getroffen maatregelen. Daarbij speelt de EU-Kaderrichtlijn Water en de EU-Habitatrichtlijn een steeds belangrijkere rol. De gegevens zoals die in 2004 zijn verzameld worden hier gepresenteerd
An assessment of the environmental toxicity of hexavalent chromium in fish
Putte, I. van der - \ 1981
Landbouwhogeschool Wageningen. Promotor(en): J.H. Koeman. - Wageningen : van der Putte - 117
toxische stoffen - anorganische verbindingen - chroom - salmonidae - zalm - forel - toxicologie - chemicaliën - osmerus - toxic substances - inorganic compounds - chromium - salmonidae - salmon - trout - toxicology - chemicals - osmerus

At present chromium is a common contaminant in surface waters in many countries. In water the metal may be present in the trivalent form (CrIII) or in the hexavalent form (CrVI), the latter of which is more toxic to aquatic organisms.
The investigations presented in this thesis were aimed at a thorough understanding of the mechanism of action of hexavalent chromium in fish. The process of uptake and elimination was studied in detail, while special attention was paid to physiological and histological alterations underlying the toxic effects. Water pH was taken into consideration as a varying environmental factor, because of its known influence on the oxidizing action of Cr(VI) and on the distribution of the ionic species of Cr(VI) in water. Rainbow trout (Salmo gairdneri) was used as the test-species.
Chapter 1 describes the effect of pH on uptake, tissue distribution and retention of Cr(VI) in trout. In trout exposed to Cr(VI) at pH 7.8 for 2-4 days the highest contents of chromium were found in gill, liver, kidney and digestive tract. Upon transfer of exposed fish to tap-water, chromium disappeared rapidly from blood, gill and digestive tract, whereas chromium contents in liver tended to remain high and in kidney even tended to increase. When the pH was decreased from 7.8 to 6.5, a different pattern of accumulation and elimination of chromium was observed. The major differences were found in the gills which concentrated significantly more chromium at pH 6.5 than at pH 7.8, irrespective of the exposure time and concentration. As the intensity of the electron -spin - resonance signal characteristic for trivalent or pentavalent chromium in the gills was somewhat higher at pH 6.5 than at pH 7.8, the differences must have been at least partly due to the higher oxidizing action of Cr(VI) at the lower pH.
Chapter 2 deals with the effect of pH on the acute toxicity of Cr(VI) to trout. The lethal action of the metal increased with decreasing pH in the range from 7.8 to 6.5. Morphological changes that could be associated with acute Cr(VI) poisoning at pH 7.8 were found in gills, kidney and stomach, whereas those at pH 6.5 appeared to be restricted to the gills. These findings are in accordance with the results obtained in the Cr- uptake experiments. Consequently, the general assumption that Cr(VI) elicits its toxic effect in some internal organ and that the gill is not the target organ in acute Cr(VI) toxicity, is only appropriate at relatively high pH levels. At pH 6.5 the gills seems to be the primary target organ.
To explain the acute toxic effects, hydrochromate (HCrO 4- and chromate (CrO 42- ) were considered as the toxic species of Cr(VI) The relative toxicities of these ionic species were calculated from empirical toxicity relationships for weak acids in fish, as described in the literature. By this calculation it was found that the relative toxicity of HCrO 4- to trout was from 3.6 to 11.9 times greater than that of CrO 42- ) depending on exposure time and fish weight.
Chapter 3 reports on an in vitro study on transfer of oxygen and chromium in gills of trout. Gills were perfused according to the isolated head perfusion technique and externally exposed to Na 2 CrO 4 solutions containing 51 CrO 42- .
The results show that the transfer of chromium is directly coupled with the transfer of oxygen from the external solution to the internal perfusion medium. Under similar conditions of oxygen transfer, however, chromium transfer was significantly more effective at pH 6.5 than at pH 8.1.
The data suggest that chromium is taken up by the blood by passive diffusion from the external solution across the epithelium of the secondary lamellae. In addition it is indicated that the availability of the metal to the fish increases with decreasing pH.
Gill preparations of trout that were structurally damaged by pre-exposure in vivo to Cr(VI) exhibited an impaired oxygen transfer.
Chapter 4 describes the effect of Cr(VI) on respiration and osmoregulation in trout. Recordings were made of the ventilation frequency, coughing rate and rate of oxygen uptake in trout subjected to sublethal concentrations of Cr(VI) for 4 days at pH 7.8 and 6.5.
During exposure no significant effect of chromium on oxygen uptake rate was detected. The ventilation frequency and coughing rate increased proportionally to an increase in metal concentration, with fish being more susceptible at the lower pH.
Alterations in blood and plasma variables determined after exposure indicated a significant dose-dependent decrease in plasma osmolality and electrolyte concentrations, and an increase in hemoglobin, hematocrit, plasma glucose and lactate levels. The pattern of these changes was dependent on pH and exposure concentration, and seemed to be related with chromiuminduced histological alterations. The results indicate, that at pH 7.8 as well as at pH 6.5 both an osmoregulatory and respiratory dysfunction are part of the physiological mechanism of hexavalent chromium toxicity.
In chapter 5 toxic effects of Cr(VI) are described in trout after prolonged exposure at different pH values for periods of up to 32 weeks. Different developmental stages were studied.
In all stages tested, fish were more susceptible to Cr(VI) at pH 6.5 than at pH 7.8. Fish in the embryo-through-juvenile stage were the most susceptible to Cr(VI) For this developmental stage it can be estimated that concentrations affecting survival lie between 0.2 and 2.0 mg/I Cr(VI) at pH 7.8 and between 0.02 and 0.2 mg/l Cr(VI) at pH 6.5.
Finally, the observed effects of a prolonged exposure are discussed in relation with the results of the short-term toxicity tests described in the preceeding chapters.
The toxicological evaluation of chromium in surface waters in the Netherlands is hampered by a lack of information on the proportion of trivalent and hexavalent forms of chromium in the total chromium content. Until now only total chromium contents have been determined at various sampling locations. If one compares the total chromium levels in Dutch surface water with the lowest toxic concentrations of Cr(VI) in trout, it can not be excluded that chromium concentrations may locally exceed toxic levels for fish. However, a final conclusion can only be drawn when additional information on the chemical status of the metal in the aquatic environment in the Netherlands has been made available.

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