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In 2010 vatte drie ondernemers het plan op om bij de Rotterdamse Fruithaven een loods en het erom heen gelegen rangeerterrein een landbouwkundige bestemming te geven. Het duurde tot 2012 voordat voldoende kapitaal en vergunningen waren geregeld en met de aanleg van Uit Je Eigen Stad begonnen kon worden. Inmiddels is er veel bereikt (waaronder een werkend aquaponics systeem met een inhoud van 125 m3) en worden groente, tilapia, Afrikaanse meerval, paddenstoelen en kippen in het eigen restaurant en in Rotterdam en omgeving verkocht. Maar de medewerkers van Uit Je Eigen Stad rusten niet en gaan door met het testen en proberen van verschillende gewassen, productiewijzen, producten, markten en evenementen. We bezochten het bedrijf en spraken met Ivo Haenen.

Scientifically, this study aimed to validate the potential of ragworm to alleviate anaemia in common sole and to identify the dietary requirements of common sole to alleviate this anaemia. At the same time it was aimed to explain part of the difference in growth between sole fed a commercial pellet and sole fed ragworm. Practically, this study aimed to develop a diet that achieves similar growth rates in sole as when fed ragworm. Sole fed commercial pellets developed nutritional anaemia. Feeding ragworm or mussel alleviates this nutritional anaemia. It is suggested that the ability of mussel or ragworm (meal) to alleviate anaemia and improve growth in sole can be explained by heme iron and high B12 levels. Yet, iron absorption in sole is high and independent of iron source. Still, heme increases the absorption of copper. The high absorption of iron and copper in sole fed heme does not affect the haematocrit (Hct) and haemoglobin (Hb) levels, which indicates the anaemia in sole is not an iron or a copper deficiency anaemia. The Hct and Hb levels in sole are affected by dietary B12. Yet, the applied levels are unable to alleviate the anaemia in sole induced by feeding commercial pellets. More options to alleviate the nutritional anaemia in common sole are discussed. Nutrients as vitamin C, B1, B2, B5 and a possible role of dietary EPO are discussed. It is suggested that the slow growth of pellet-fed sole might be due to the low Hct and Hb levels, which hampers the uptake of oxygen, and thus also the overall metabolic capacity, including the scope for growth. Discussed is a 7°C difference in the “optimal” temperature between sole fed ragworm and the 2nd generation pellet and that the “worm effect” is dependent on temperature. However, the growth rate of sole fed the 3rd generation pellet at 18.4°C was comparable to the growth rate of sole fed ragworm, which could not have been the consequence of increasing Hct and Hb levels as these were comparable to levels found in sole fed commercial pellets. Yet, B12 levels in blood plasma of sole are up to 200 times those of other (fish) species. Hence, we inferred on the possibility of a specific metabolic function of B12 in respiration in sole. In addition, the economic and practical impact of the improved growth rate in sole culture is discussed. Finally, several suggestions for future research are given.

Fish farming is growing but is also facing challenges regarding economic viability and environmental sustainability. Selective breeding could enhance the sustainability of fish farming by changing animal performances. Thus, our aim was to develop sustainable breeding goals by using economic (EV) or environmental values (ENV) to weigh the traits to improve. EV and ENV represent the economic and environmental impacts of improving a trait. They were calculated using a bioeconomic model combined with a life cycle assessment. We showed that the EV and ENV of traits change with the factor constraining the production of the farm. It suggests that breeding goals should be finely tuned according to the limiting factor to maximize economic or environmental responses. In addition, we showed that improving feed conversion ratio is a major trait to improve because it always increases profit and decreases environmental impacts. We conclude that it is possible to develop breeding programs enhancing the sustainability of fish farming by improving the right trait in the right production system.

Diet composition, ingredient and nutrients, are important to consider for maintaining intestinal functions. Studies on both positive (using feed additives) and negative effects (using high inclusion of plant ingredients) of fish feeds are numerous, however, between studies results are often highly variable, both in type of response and in significance. The central hypothesis of this study was that adverse environmental conditions may aggravate negative effects of plant ingredients on the intestinal functions to the extent that mild effects become severe and perceptible. To do so, dietary factors and environmental conditions were evaluated and the interaction between diet composition and environmental conditions were studied in Nile tilapia. In Chapter 2, six common raw materials including hydrolysed feather meal (HFM), soybean meal (SBM), rice bran (RB), rapeseed meal (RM), sunflower meal (SFM) and dried distiller grains with solubles (DDGS) were chosen to determine the effect of nutrient digestibility, nitrogen/energy balance and changes in intestinal morphology. The study demonstrated that feed ingredients do have an impact on the alteration in intestinal parameters, but also on the nutrient digestibility and the nitrogen/energy balance. Although being well digested, soybean meal caused the most obvious alteration in the intestinal morphology. These alterations were not related to the nutrient digestibility nor to nitrogen/energy balance parameters. Soybean meal, causing the most alterations in the intestinal morphology, was further used in all subsequent chapters of this thesis. Chapter 3 and 4 described the interaction between diet composition and environmental conditions on the intestinal functions. This was studied with two different environmental conditions, dissolved oxygen (Chapter 3) and salinity (Chapter 4). These two chapters evaluated whether suboptimal environmental conditions (low dissolved oxygen or elevated salinity in water) may interact with a soybean meal based diet in nutrient digestion and intestinal morphology of tilapia. The study demonstrated that environmental stressors can aggravate/reveal the negative intestinal morphology changes induced by a soybean meal based diet. However, these effects of adverse environmental conditions on the intestinal functions were not homogenously dispersed over the whole intestinal length. The effect of salinity on the intestinal morphology occurred predominantly in the distal intestine, whereas the effect of low oxygen concentration was more visible at the proximal intestine. Alterations in the intestinal morphology, as found in this study, have wider effects on the performance of the affected fish. In Chapter 3, the protein digestibility decreased under hypoxic conditions at week 8, which parallels with the time related alteration in intestinal morphology. Chapter 4 showed that when fish were raised at 15 ‰ salinity, nutrient digestibility increased; however, this positive effect decreased when the intestinal morphology changed. The study also found that the combined effect of a soybean meal based diet and hypoxia was stronger compared to the combination with elevated salinity. Therefore, the combination with hypoxia was further used in the next study of this thesis. In Chapter 5, the combination of hypoxic condition and a soybean meal based diet was chosen to test the hypothesis that only under stressful conditions, the effects of feed additives can be noticed. The impact of two dietary organic acids, formic acid and butyric acid, on nutrient digestibility and intestinal morphology was determined under optimal (normoxia) and suboptimal conditions (hypoxia). The results showed that although organic acids did not significantly improve growth performance and nutrient digestibility under normoxic condition, they did so under hypoxic conditions. Fish fed organic acid supplemented diets all showed improvements in the morphology of intestine under normoxic conditions, and these effects were more enhanced under hypoxic conditions. This indicates that environmental conditions can alter the effect of organic acid on nutrient digestibility and intestinal morphology in tilapia. Finally, Chapter 6 provided a synthesis of the main findings, and a reflection on the methodologies used in Chapters 2-5 as well as a discussion on the relevance of this study to aquaculture. It is concluded that although being well digested, soybean meal caused the most obvious alteration in intestinal morphology. The adverse environmental conditions aggravated negative effects of soybean meal based diets on the intestinal functions to the extent that mild effects become severe and visible. The negative effect on intestinal morphology of soybean meal in the diet is enhanced at low oxygen level and at elevated salinity. The effect of salinity on the intestinal morphology occurs predominantly in the distal intestine, whereas the effect of low oxygen concentration is more visible at the proximal intestine. The thesis indicated that the impact of organic acids on intestinal functions is dependent on environmental conditions, being more pronounced under challenging conditions (e.g. hypoxia). Therefore, studies on both positive (using feed additives) and negative effects (using high inclusion of plant ingredients) of dietary factors should be done under suboptimal conditions.

The aim of this thesis was to develop a sustainable low cost breeding program for Nile tilapia that addresses both genetic and economic aspects of smallholder fish farmers in Kenya. First, Analytical Hierarchy Process Technique was used to define a breeding goal based on farmer’s preferences for traits. Farmers’ preferences for traits differed significantly depending on income and market orientation. Low and medium income farmers preferred harvest weight (HW) while high income farmers preferred growth (GR) and survival (S) traits. Grouping farmers according to market objective (fingerling production or fattening) showed that fingerling producers preferred GR and S while fattening farmers preferred HW and S. Consensus preference values were obtained using weighted goal programming and these values were used to derive desired gains for a breeding goal that takes into account farmers’ diverse backgrounds and preferences for traits. Secondly, the existence of genetic variation for traits of interest was investigated. Substantial additive genetic effects for HW, GR and shape traits were present that can be exploited through selection under low input production system. Heritability estimates for HW, GR and shape were 0.21 ± 0.03, 0.26 ± 0.04 and 0.12 ± 0.03 for mixed sex (nucleus) respectively. The calculation of economic values for breeding goal traits revealed that economic values for GR differed depending on the definition of the breeding goal and that selection for feed efficiency is the key factor to economic profitability of Nile tilapia breeding programs. A significant genotype by environment re-ranking was found for GR between the mixed sex nucleus and monosex production environments. Genotype by environment interaction (G x E) led to lower genetic gain for GR in production environment. Incorporating sib information from monosex production environment into the selection index resulted in a more accurate estimation of breeding values which increased genetic gain in growth. Using desired gain approach, weights for desired gains in harvest weight, growth rate and survival were derived that maximized genetic gains for these breeding goal traits. It is concluded that these results can be used to develop a sustainable centralized breeding program. However, a reliable well planned and organized decentralized strategy for dissemination of genetically improved fry of Nile tilapia to farmers is paramount.

New and alternative plant ingredients are increasingly incorporated in fish feed due to the scarcity of captured fish and increased fishmeal and fish oil prices. As a result, current fish feeds are characterized by a highly variable ingredients composition, leading to a similar variability in the dietary macronutrients composition, especially the carbohydrates fraction. Appropriate formulation of the energy component in fish feeds requires information on nutrient digestibility, energy requirements for maintenance, and the efficiency of utilization of digestible energy for growth (kgDE). In fish feed formulation, the energy evaluation is based on digestible energy (DE) basis. The main assumptions of this DE system are that maintenance requirements and kgDE are independent of dietary factors. The main objective of this thesis was to evaluate and improve the DE system for Nile tilapia. Data showed that, opposite to what is assumed in literature and irrespective of the feeding level applied, an optimal digestible protein to digestible energy ratio (DP/DE) for young Nile tilapia could not be detected. In addition, it was expected that Nile tilapia would show a maximal protein deposition in relation to a wide range of DP/DE ratios, however, this was either observed. Further investigations showed that different body compartments/organs responded differently in terms of protein and fat composition as a result of changes in the dietary DP/DE ratio. In tilapia, viscera and the “rest” fraction (head, skin, fins and bones) were the main site for fat retention. In addition, protein content of fillets seems to be constant (about 17%) and not affected by dietary factors in Nile tilapia. In addition, the effect of using new plant ingredients in Nile tilapia diets was also investigated. The results showed that the ingredients composition had an effect on the maintenance requirements of Nile tilapia. Further, changes in the ratio of starch vs non starch carbohydrates revealed that energy retention was lower when more dietary fibers were included. In addition, the net energy retention differed also when the levels of digestible protein, fat and carbohydrates changed in the diets. The latter results proved that kgDE was not constant and was dependent on diet composition. All aforementioned results led us to calculate the energetic efficiencies of digestible protein, fat and carbohydrates for net energy retention. These estimated efficiencies were used to propose a net energy evaluation system being feasible for Nile tilapia.

Op een industrieterrein in Eindhoven worden sinds 2009 stueren gehouden voor de kaviaarproductie. Het bedrijf, Anna Royal Dutch Caviar geheten, is eigendom van de heren Oleg Salkazanov en Vusal Huseynov.

De aquacultuur is gebaat bij een fittere vis die geen misvormingen vertoont, die niet snel ziek wordt, die goed groeit en die een kwaliteitsproduct oplevert.

Egypte is op het Afrikaanse continent het land met veruit de grootste visteeltproductie. Het grootste deel van de aquacultuurproductie bestaat uit zoetwatervissoorten. Dat deze groei kon plaatsvinden in een land waar zoetwater beperkt aanwezig is, kan opmerkelijk genoemd worden. Nog opmerkelijker wordt het als men zich realiseert dat deze groei plaatsvindt in een land waar het viskwekers verboden is van irrigatiewater gebruik te maken, tenzij het water voor een pootvisbedrijf bestemd is. Integratie van visteelt en landbouw kan tot efficiënter watergebruik leiden, en zou in een land waar zoetwater schaars is, aangemoedigd dienen te worden. Maar niet in Egypte. Dit artikel gaat over de wetten en regels die de toepassing van geïntegreerde visteelt belemmeren, en doet verslag van de resultaten van een studie die wat cijfers over het waterverbruik door geïntegreerde bedrijven boven tafel bracht.

In een studie volgens het 'Fork to Farm' principe is de yellowtail kingfish (Seriola lalandi) als potentieel succesvolle soort voor de Nederlandse aquacultuursector aangewezen. Dit artikel beschrijft de eerste resultaten van het onderzoek door Imares naar de teelt van deze soort in Nederlandse recirculatiesystemen.

Grondsmaak is wereldwijd een van de belangrijkste beperkende factoren voor de afzet van kweekvis afkomstig uit vijvers en recirculatiesystemen. Dit wordt vooral veroorzaakt door de lage waardering van consumenten voor kweekvis met grondsmaak. Marktprijs en marktvolume komen daardoor onder druk te staan. Daarnaast brengt de bestrijding van grondsmaak extra kosten met zich mee voor de producent. Ook in Nederlandse kweekvis komt grondsmaak voor. In Nederland wordt op verschillende fronten gewerkt aan het voorkomen en bestrijden van grondsmaak. In het eerste deel van deze serie over grondsmaak (Aquacultuur 2011, nr. 2) werd vooral ingegaan op de achtergronden en gevolgen van grondsmaak. In dit tweede deel wordt dieper ingegaan op de diverse aspecten van het bestrijden van grondsmaak in kweekvis.

In de aquacultuur zijn de afgelopen jaren veel ontwikkelingen geweest op het gebied van genetische verbetering. Wereldwijd zijn fokprogramma's toegepast voor economische relevante soorten. Belangrijke voorbeelden van deze soorten zijn onder andere Atlantische zalm, regenboogforel, Europese zeebaars, goudbrasem, Nijltilapia en enkele garnalensoorten. Door de belangrijke bijdrage aan economische haalbaarheid van aquacultuurondernemingen zijn fokprogramma's dan ook niet meer weg te denken. Door Wageningen UR worden momenteel fokprogramma's ontwikkeld voor Nijltilapia, Noordzeetong, tarbot en er wordt gewerkt aan selectiemethoden voor regenboogforel en yellowtail kingfish. Genetische vooruitgang door deze fokprogramma's heeft al duidelijke groeiverbetering geleverd voor Nijltilapia in Nederlandse recirculatiesystemen en de verwachtingen bij tong en tarbot liggen op ca.+25%.

In dit artikel wordt de rol van de microbiële gemeenschap in de darm van vissen beschreven en wordt een overzicht gegeven van de belangrijkste huidige kennis en inzichten. Ook wordt een korte beschrijving gegeven van het ministerie van EL&I (voormalig LNV) gefinancierde project "Visgezondheid in RAS" en wordt aangestipt wat we verwachten te leren van dit project.

'Viskwekers kunnen niet achterover leunen,' kopte het LEI op haar website in februari 2011. Aanleiding voor dit bericht was de publicatie van het rapport Actieplan visteelt; eindrapportage (Van Duijn et al., 2010). Hieruit bleek dat het niet goed gaat met de Nederlandse visteelt en dat eigenlijk alleen de kwekers zelf iets aan deze situatie kunnen veranderen. Sindsdien hebben de Nederlandse viskwekers niet stil gezeten. Zo heeft een aantal viskwekers zich, met ondersteuning van het LEI en IMARES verenigd in een Kenniskring Aquacultuur. In deze Kenniskring zijn viskwekers bezig met het plannen van concrete acties om de concurrentiekracht van de sector te vergroten.

Grondsmaak is wereldwijd een van de belangrijkste beperkende factoren voor de afzet van kweekvis afkomstig uit vijvers en recirculatiesystemen. Dit wordt vooral veroorzaakt door de lage waardering van consumenten voor kweekvis met grondsmaak. Marktprijs en marktvolume komen daardoor onder druk te staan. Daarnaast brengt de bestrijding van grondsmaak extra kosten met zich mee voor de producent. Ook in Nederlandse kweekvis komt grondsmaak voor. In Nederland wordt op verschillende fronten gewerkt aan het voorkomen en bestrijden van grondsmaak. In dit artikel (dat uit twee delen bestaat) wordt het grondsmaakprobleem en het daaraan gekoppelde onderzoek beschreven. In dit eerste deel wordt vooral ingegaan op de achtergronden en gevolgen van grondsmaak.

In 2010 hebben twee Vietnamese onderzoeksinstituten onder begeleiding van Wageningen UR het inkomende water en het water dat de vijvers van vier pangasiuskwekerijen verlaat, maandelijks bemonsterd en de gemonitord. Doel was om een simpele methode te vinden om hoeveelheid en kwaliteit van het afvalwater te meten om hiermee bedrijven en organisaties die betrokken zijn bij certificering van kwekerijen te kunnen adviseren. De effecten van de kwekerijen op het milieu vormen een onderdeel van de certificering en dienen door de kwekerijen geregeld gemeten te worden. In dit artikel wordt verslag gedaan van de resultaten van deze studie.

IMARES heeft in 2008 een inventarisatie uitgevoerd van de de waterkwaliteit in meervalkwekerijen. Om in te schatten of er sprake is van niet optimale waterkwaliteit zijn de meetresultaten vergeleken met literatuurgegevens. Hieruit bleek dat er over het effect van ammoniak op meerval onvoldoende bekend is om goed in te kunnen schatten of de soms hoge concentraties in het water slecht zijn voor de groei en het welzijn van de vissen. Daarom is een experiment opgezet om het effect van ammoniakconcentratie in het kweekwater voor Afrikaanse meerval vast te stellen

De toekomst van de visteelt in Nederland was één van de thema's die begin 2010 binnen de Nederlandse aquacultuursector veel aandacht trok. Op dit moment is dit thema ook bij onze buren in Vlaanderen actueel. In dit artikel wordt het project AquaVlan belicht dat zich tussen Nederland en België afspeelt. AquaVlan richt zich op de duurzame kweek van schelpdieren, vissen en zilte groenten. Het algemeen projectdoel is het leggen van de fundamenten van een economisch, sociaal en ecologisch duurzame aquacultuursector binnen de Grensregio, zodat de huidige, zeer beperkte, aquaculuursector kan uitgroeien tot een sector van economische betekenis. Het Interreg IVa programma, Vlaamse provincies, de Vlaamse Overheid en de provincie Zeeland financiëren het project.

Europa, waar de belangrijke kweeksoorten zalm, zeebaars, zeebrasem en tonijn vooral in kooien op zee gekweekt worden, is een buitenbeentje in de mondiale aquacultuur scene. Op wereldschaal wordt het leeuwendeel van vis en schaaldieren gekweekt in vijvers. Van de op gewichtsbasis 20 belangrijkste gekweekte vissoorten worden alleen zalm en regenboogforel niet hoofdzakelijk in vijvers gekweekt. Van de mondiale productie van gekweekte garnalen wordt meer dan 95% in vijvers gekweekt. Hoe duurzaam is de teelt in vijvers, en biedt vijverteelt de oplossing om te voldoen aan de groeiende vraag naar vis en schaaldieren in de wereld?

De visteelt in Nederland heeft het zwaar de afgelopen jaren. Naar aanleiding van een vraag van Landbouw Natuurbeheer en Voedselkwaliteit onderzocht he Landbouw Economisch Instituut (LEI), in samenwerking met IMARES en externe deskundigen de oorzaken van de achteruitgang. Tijdens de NGVA bijeenkomst van 21 januari 2010 in Wageningen werden de voorlopige resultaten gepresenteerd. Belangrijke elementen zijn de toegenomen concurrentie van importproducten, hoge kosten en een gebrek aan ondernemerschap. Het rapport over de achteruitgang van de visteelt zal in de loop van 2010 uitkomen

Per 1 februari 2009 ging het project PROMICROBE van start. Het project richt zich op de invloed van bacteriën op de ontwikkeling, groei, productie en overleving van vissen in teeltsystemen. Een vergelijking wordt gemaakt tussen tilapia, kabeljauw en zeebaars. Het einddoel van het onderzoek is het bedrijfszeker kweken van gezonde vissen in duurzame en stabiele teeltystemen

Aquacultuuronderzoek is een van de werkvelden van IMARES. Onderzoekers van IMARES gaan de komende afleveringen delen van hun werk presenteren. In dit eerste artikel wordt een overzicht gegeven van het instituut, de manier waarop gewerkt wordt en de variatie in het onderzoek

Het kweken van zeevis gebeurt in Nederland dicht langs de kust waar zeewater beschikbaar is en het zoute afvalwater weer terug kan naar zee. In Franeker is een tarbotkweker "Frisian Fisch Farms" gevestigd op een tiental kilometers vanaf de Waddenkust. In tegenstelling tot veel andere viskwekers is Floris Sinnema uit op samenwerking met collega's

Honden, koeien, paarden, varkens én vissen. Wageningen UR staat bij het grote publiek bekend als landbouwuniversiteit, maar dit kennisinstituut voor Life Sciences is wereldwijd ook vooraanstaand in de viskweek. Sietze Leenstra (62) is al 32 jaar werkzaam bij De Haar Vissen, het ‘natte lab’ van de WUR. In dit artikel een portret van deze expert op het gebied van kweekvis en zijn werkomgeving.

Aquaculture is essential to meet the current and future demands for seafood to feed the world population. Atlantic salmon and rainbow trout are two of the most cultured aquaculture species. A pathogen that threatens these species is salmonid alphavirus (SAV). A current inactivated virus vaccine against SAV provides cross-protection against all SAV subtypes in salmonids and reduces mortality amongst infected fish. However, protection is not 100% and due to virus growth at low temperature, the vaccine production process is time consuming. In addition, the vaccine needs to be injected into the fish, which is a cumbersome process. The work described in this thesis aimed to increase the general knowledge of SAV and to assess current vaccine technologies, and to use this knowledge in designing next-generation vaccines for salmonid aquaculture. An alternative cell line to support SAV proliferation was identified, however, the virus production time could not yet outcompete the current SAV production system. Making use of the baculovirus insect cell expression system, multiple enveloped virus-like particle (eVLP), and core-like particle (CLP) prototype vaccines were produced in insect cells at high temperature. An in vivo vaccination study showed, however, that these vaccines could not readily protect Atlantic salmon against SAV. The low temperature-dependent replication of SAV was attributed to the glycoprotein E2, and it was found that E2 only correctly travelled to the cell surface at low temperature, and in the presence of glycoprotein E1. The biological impact of this finding was confirmed in the development and in vivo testing of a DNA-launched replicon vaccine. The effective DNA-launched replicon vaccine was extended by delivery of the capsid protein in trans. It was hypothesized that viral replicon particles (VRP) were formed in vivo, which would cause an additional single round of infection and might further elevate the immune response in comparison to the replicon vaccine. A second animal trial indicated that the inclusion of capsid did not yet improve vaccine efficacy. This trial however did show that a DNA vaccine transiently expressing the SAV structural proteins provided superior protection over both replicon vaccines (with and without capsid). In this thesis, some virus characteristics, such as the cause of temperature-dependency of SAV replication, of an unique aquatic virus were further explored. The production and in vivo testing of multiple next-generation vaccines defined the prerequisites for induction of a potent immune response in Atlantic salmon. A prototype DNA-launched replicon vaccine has shown potential for further development. The research described in this thesis contributes to the development of next-generation vaccines in the challenging area of fish vaccinology.

The aim of this thesis was to document improvements in sustainability indicators of striped catfish (Pangasianodon hypophthalmus, Sauvage, 1878) production through the application of recirculation and waste treatment techniques. To be able to document improvements in sustainability, in each system studied the same set of twenty sustainability indicators were measured. Indicators related to the use of fingerlings, water, diesel oil, electricity, labor, chemicals and antibiotics. Also, indicators related to nutrient utilization efficiencies and waste discharge were monitored. In addition, a sampling scheme, allowing to calculate organic matter, nitrogen, phosphorous and chemical oxygen demand mass balances covering a full production cycle and applicable in different production systems, was developed. Overall, from a sustainability point of view, striped catfish culture in ponds compared well to other important aquaculture species. Although favorable, it was concluded that water, chemicals and antibiotics use, survival, and the amounts of waste discharged could be further reduced through recirculation and treatment of solid wastes. The realized improvements through RAS technology and waste treatment technology were quantified in lab or pilot scale experiments. Large improvements were realized for water, antibiotic and chemical use, survival, waste discharge and color grade of striped catfish fillets at harvest. In addition, in RAS, utilization efficiencies of nutrients supplied through feeding were improved. Solid wastes removed from ponds or RAS could be partially re-used by making compost or producing methane for generating electricity. Another approach tested was the integration of a denitrification reactor in the recirculation system, which allowed to decompose solid waste and reduce nitrogen discharge. Denitrification in RAS did not affect fish growth, nutrient retention efficiencies and the quality of the fish fillets produced, and thus also improved sustainability of striped catfish farming. In conclusion, application of recirculation and waste treatment techniques tested in this thesis improved the sustainability for striped catfish culture. The challenge remains to scale up RAS and waste treatment technology for striped catfish to the production volumes handled in outdoor ponds without raising production costs.

Het ministerie van EZ heeft IMARES Wageningen UR gevraagd om een overzicht te maken van de aanvraagprocedures voor benodigde vergunningen en bepalende regelgeving voor het opzetten van een viskweekbedrijf. In dit rapport zijn de procedures opgedeeld in de twee hoofdonderdelen Bouw en Milieu, en Dieren. De laatste jaren zijn met de invoering van de Wet algemene bepalingen omgevingsrecht (Wabo, 2010) en de Waterwet (2009) tientallen wetten en regelgevingen samengevoegd en geïntegreerd. Dit heeft onder andere geleid tot de omgevingsvergunning, milieuvergunning en watervergunning, die van belang zijn bij het starten van een viskweekbedrijf. Via online modules kan gecontroleerd worden welke vergunningen of onderdelen van de vergunningen nodig zijn (de vergunningcheck), en de aanvraag van de benodigde vergunningen verloopt ook via een van deze modules. De aanvraag wordt automatisch naar de bevoegde lokale of regionale overheid gestuurd, die deze afhandelt. Door al deze maatregelen zijn de procedures om de verschillende benodigde vergunningen aan te vragen sterk versimpeld. De inhoudelijke wet- en regelgeving is hiermee echter niet versimpeld, en door de sterke digitalisatie is het moeilijk om gespecialiseerde ambtenaren rechtstreeks te benaderen. Op het gebied van de dieren zijn de vergunningen en de regelgeving veelal nationaal en/of Europees georganiseerd, en fungeert in de meeste gevallen de nVWA als centraal orgaan waarbij de regelgevingen kunnen worden bestudeerd en vergunningen moeten worden aangevraagd. De duur en de kosten voor het verkrijgen van de vergunningen zijn sterk afhankelijk van de precieze vergunningen of onderdelen van vergunningen die nodig zijn, en van de gemeente waar de vergunningen worden aangevraagd. Het invullen van de vergunningcheck is hierbij de belangrijkste leidraad. Ondernemers moeten rekening houden met een procedure tijd van zes maanden.

Het ministerie van EZ heeft IMARES Wageningen UR gevraagd om een overzicht te maken van de aanvraagprocedures voor benodigde vergunningen en bepalende regelgeving voor het opzetten van een viskweekbedrijf. In dit rapport zijn de procedures opgedeeld in de twee hoofdonderdelen Bouw en Milieu, en Dieren. De laatste jaren zijn met de invoering van de Wet algemene bepalingen omgevingsrecht (Wabo, 2010) en de Waterwet (2009) tientallen wetten en regelgevingen samengevoegd en geïntegreerd. Dit heeft onder andere geleid tot de omgevingsvergunning, milieuvergunning en watervergunning, die van belang zijn bij het starten van een viskweekbedrijf. Via online modules kan gecontroleerd worden welke vergunningen of onderdelen van de vergunningen nodig zijn (de vergunningcheck), en de aanvraag van de benodigde vergunningen verloopt ook via een van deze modules. De aanvraag wordt automatisch naar de bevoegde lokale of regionale overheid gestuurd, die deze afhandelt. Door al deze maatregelen zijn de procedures om de verschillende benodigde vergunningen aan te vragen sterk versimpeld. De inhoudelijke wet- en regelgeving is hiermee echter niet versimpeld, en door de sterke digitalisatie is het moeilijk om gespecialiseerde ambtenaren rechtstreeks te benaderen. Op het gebied van de dieren zijn de vergunningen en de regelgeving veelal nationaal en/of Europees georganiseerd, en fungeert in de meeste gevallen de nVWA als centraal orgaan waarbij de regelgevingen kunnen worden bestudeerd en vergunningen moeten worden aangevraagd. De duur en de kosten voor het verkrijgen van de vergunningen zijn sterk afhankelijk van de precieze vergunningen of onderdelen van vergunningen die nodig zijn, en van de gemeente waar de vergunningen worden aangevraagd. Het invullen van de vergunningcheck is hierbij de belangrijkste leidraad. Ondernemers moeten rekening houden met een procedure tijd van zes maanden.

In response to increasing concerns about sustainable production, a growing number of European customers expect seafood products to be certified, for example by the Aquaculture Stewardship Council (ASC) certification. Water purification technologies such as Recirculating Aquaculture Systems (RAS) could be a potential solution to reduce waste discharge and to improve water quality in fish ponds as a response to environmental regulations. In order to provide useful insights to consider investments in RAS, the overall objective of this thesis was to perform an economic analysis of technological innovations such as RAS to improve the sustainability of pangasius production in Vietnam. This thesis first uses Data Envelopment Analysis to measure input- and output-specific technical and scale inefficiency of pangasius farmers in the traditional system and uses a bootstrap truncated regression to assess the impact of farmers’ demographics and farm characteristics on these technical inefficiencies. Second, the economic feasibility of RAS in pangasius farming is analysed using a capital budgeting approach and stochastic simulation accounting for uncertainty in key parameters. Next, key determinants influencing the adoption of RAS by pangasius farmers are investigated using a choice experiment. Finally, price transmission along the international supply chain of pangasius, from the Vietnamese farm to the Polish retail stage is analysed using a vector autoregressive error correction model framework. The results show that inadequate management skills in using capital assets and improper methods for producing fish are the main challenges for enhancing the performance of Vietnamese pangasius production. Location of the farm in a saltwater intrusion area is positively associated with inefficiency of producing fish. The results suggest further that when shifting from the traditional system to RAS, the Net Present Value (NPV) of the investment in RAS is expected to substantially increase, for both medium (1-3 ha) and large (equal or greater than 3 ha) farms. Lack of trust in receiving a price premium, inadequate access to finance and uncertainty about the actual performance of RAS systems are constraints for the adoption of RAS. Finally, our study provides evidence that price signals at the Polish-Vietnamese retail stage were transmitted back to wholesale, export and Vietnamese pangasius farms stages.

Aquaculture has realized considerable growth over the past years while the world demand on seafood has been increasing. As aquaculture intensifies, the production sector needs to tackle major bottlenecks such as suboptimal growth and high and unpredictable mortality, especially in larval cultures. Fish-microbe interactions are closely related to overall fish health. To obtain a healthy and resilient microbial community (MC), it is important to understand the underlying mechanisms of microbial colonization in the fish gut. The goal of this thesis was to investigate the role of water and feed microbial communities on shaping gut communities during early development of Nile tilapia. To determine the contribution of stochasticity to overall variation, we first characterized the spatio-temporal variation in MC composition between individuals reared within the same or in replicate recirculating or active suspension systems (RAS vs. AS). Highly similar MCs developed in the gut when larvae shared the same water and diet. Rearing larvae in replicate production systems resulted in significantly different gut communities indicating that compositional replication of the MCs of an ecosystem is not fully predictable. We found that mainly water MCs, and to a lesser degree feed MCs, were associated with changes in MCs. Thus, we could conclude that steering gut MCs can be possible through water MC management tailored on the specifications of the rearing system in use. Next, the possibility of early life steering of gut communities via microbial manipulations of feed MCs was explored. We hypothesized that gut microbial composition is strongly shaped by selective pressures in the gut and by the MCs present in the water. Thus similar MCs should develop between treatments regardless of the dietary treatments. Fish larvae were fed either a control feed or the control feed containing MCs derived from aerobic, methanogenic or denitrifying sludge reactors. We found that gut microbiota shared a much higher number of operational taxonomic units (OTUs) with microbiota in sludge-based feeds than with water, resulting in distinct gut MCs between treatments. Our findings suggest that Nile tilapia gut MC has a certain plasticity, which makes it amenable to interventions through proper feed microbial management. Subsequently, we tested the imprinting effect of early exposure to the probiotic Bacillus subtilis on shaping gut MC composition even after the administration of the probiotic discontinues. For this, we constrained the initial contact with microbes from the environment by producing axenic tilapia larvae, which were then exposed to normal husbandry conditions. Early life probiotic exposure affected gut MC composition during B. subtilis administration but also within the first two weeks after its administration stopped, thus indicating that early exposure to the probiotic strain via the water had a sustained impact on gut MC composition. Finally, overall conclusions and practical implications of our results for aquaculture production were presented. A meta-analysis was also performed to examine (1) the phylogenetic similarity among gut MCs of the same and different fish species reared in different habitats, fed different diets and at different developmental stages and (2) the factors primarily shaping gut MCs. We showed that the selective pressure responsible in shaping gut MC composition highly depends on the host as gut communities clustered primarily together by host and to a lesser extent reflected differences in habitat and diet. The phylogenetic analysis of gut communities revealed a clear clustering by study thus indicating that manipulation of gut communities is conceivable. Study-to-study variation could be attributed to the methodology used for MC analysis highlighting also the importance of methodological uniformity when comparisons between studies are made. Overall, this thesis provided fundamental knowledge on MC composition and development in aquaculture rearing systems. Although the insights generated by this thesis are still premature to fully explain, predict or steer MC composition, and though additional studies are needed, we believe that, in the long run, this approach will facilitate the development of safe and effective methods for manipulating gut microbial composition to promote fish health in aquaculture rearing systems.

Aquaculture has realized considerable growth over the past years while the world demand on seafood has been increasing. As aquaculture intensifies, the production sector needs to tackle major bottlenecks such as suboptimal growth and high and unpredictable mortality, especially in larval cultures. Fish-microbe interactions are closely related to overall fish health. To obtain a healthy and resilient microbial community (MC), it is important to understand the underlying mechanisms of microbial colonization in the fish gut. The goal of this thesis was to investigate the role of water and feed microbial communities on shaping gut communities during early development of Nile tilapia. To determine the contribution of stochasticity to overall variation, we first characterized the spatio-temporal variation in MC composition between individuals reared within the same or in replicate recirculating or active suspension systems (RAS vs. AS). Highly similar MCs developed in the gut when larvae shared the same water and diet. Rearing larvae in replicate production systems resulted in significantly different gut communities indicating that compositional replication of the MCs of an ecosystem is not fully predictable. We found that mainly water MCs, and to a lesser degree feed MCs, were associated with changes in MCs. Thus, we could conclude that steering gut MCs can be possible through water MC management tailored on the specifications of the rearing system in use. Next, the possibility of early life steering of gut communities via microbial manipulations of feed MCs was explored. We hypothesized that gut microbial composition is strongly shaped by selective pressures in the gut and by the MCs present in the water. Thus similar MCs should develop between treatments regardless of the dietary treatments. Fish larvae were fed either a control feed or the control feed containing MCs derived from aerobic, methanogenic or denitrifying sludge reactors. We found that gut microbiota shared a much higher number of operational taxonomic units (OTUs) with microbiota in sludge-based feeds than with water, resulting in distinct gut MCs between treatments. Our findings suggest that Nile tilapia gut MC has a certain plasticity, which makes it amenable to interventions through proper feed microbial management. Subsequently, we tested the imprinting effect of early exposure to the probiotic Bacillus subtilis on shaping gut MC composition even after the administration of the probiotic discontinues. For this, we constrained the initial contact with microbes from the environment by producing axenic tilapia larvae, which were then exposed to normal husbandry conditions. Early life probiotic exposure affected gut MC composition during B. subtilis administration but also within the first two weeks after its administration stopped, thus indicating that early exposure to the probiotic strain via the water had a sustained impact on gut MC composition. Finally, overall conclusions and practical implications of our results for aquaculture production were presented. A meta-analysis was also performed to examine (1) the phylogenetic similarity among gut MCs of the same and different fish species reared in different habitats, fed different diets and at different developmental stages and (2) the factors primarily shaping gut MCs. We showed that the selective pressure responsible in shaping gut MC composition highly depends on the host as gut communities clustered primarily together by host and to a lesser extent reflected differences in habitat and diet. The phylogenetic analysis of gut communities revealed a clear clustering by study thus indicating that manipulation of gut communities is conceivable. Study-to-study variation could be attributed to the methodology used for MC analysis highlighting also the importance of methodological uniformity when comparisons between studies are made. Overall, this thesis provided fundamental knowledge on MC composition and development in aquaculture rearing systems. Although the insights generated by this thesis are still premature to fully explain, predict or steer MC composition, and though additional studies are needed, we believe that, in the long run, this approach will facilitate the development of safe and effective methods for manipulating gut microbial composition to promote fish health in aquaculture rearing systems.

Vijvers kunnen een aanzienlijke bijdrage leveren aan de nutriëntenkringloop op gemenge landbouwbedrijven. Het integreren van water- en landgebonden productie in gemengde bedrijven kan leiden tot een verhoogde efficiëntie van het nutriëntengebruik. Bij evaluatie van de visteelt wordt vaak alleen gekeken naar de oogst zonder aandacht voor andere voordelen van visteelt zoals waterbeschikbaarheid of efficiëntie van nutriëntengebruik. Bovendien verkiezen boeren vaak geformuleerde voeders, hoewel het voordeel voor de oogst hiervan niet evident is in de gemiddelde eenvoudige onbeluchte vijvers. Een onderzoeksproject is gestart om mogelijkheden voor verbetering in kaart te brengen

De rijzende ster op het gebied van visteelt in Afrika is Egypte. Het heeft veruit de grootste visteeltproductie van Afrika. Vooralsnog wordt vooral de binnenlandse markt bediend en het einde is nog niet in zicht

In Nederland kweken we paling, meerval tilapia, tong en tarbot, maar zijn dat nou de soorten die hiervoor het meest geschikt zijn? Zijn er andere soorteen die meer potentie bieden voor de Nederlandse aquacultuur? Die vraag heeft het Nederlands Instistuut voor Visserij Onderzoek in opdracht van het ministerie van LNV proberen te beantwoorden

Contrary to the global trend of specialization within agriculture, the rice-based Vietnamese production systems have diversified into integrated agriculture-aquaculture systems. Economic liberalization in 1986 resulted in an explosive increase in rice production and a rapid diversification. This paper describes the history and dynamics of these systems in the Mekong Delta, and the farmers' decisionmaking in this process. Subsequently, we use fuzzy logic to simulate farmers' decisions to opt for no aquaculture or one of four fish-production systems: waste-fed, pellet-fed, rice-fish, and ditch-dike, i.e., fish-fruit. In a reaction to changing market opportunities the farmers developed these systems either from the depressions left after building a homestead or after raising dikes to improve irrigation and drainage for rice and fruit trees. The decision-making was simulated in a two-level hierarchy decision-tree. The first layer handles the farmer's production preferences for rice, fruit or fish, with composed variables for land, water, labour, capital and market. The second layer simulates the choice between five options: no fish, and the four alternative fish-production systems. The model allowed a farmer to practise different aquaculture systems at the same time. The fuzzy model simulation predicted the frequency distribution of fish production systems fairly accurately, but performed poorly when classifying individual farmers. To improve the accuracy of the simulation, additional rules can be specified and more factors considered for each product by adding a third layer to the decision-tree and replacing the composed variables with fuzzy rules.

Nederland kent een rijke traditie in aquatische ecologie. Diverse universiteiten, HBO-opleidingen en instellingen houden zich bezig met de biologie van zowel het zoete als het zoute water. Opmerkelijk is dat er daarbij verhoudingsgewijs weinig aandacht wordt besteed aan vissen. Wageningen Universiteit en Research Centrum (WUR) vormt daarop een uitzondering. Binnen deze universiteit richten diverse onderzoeksgroepen zich op vissen. De bekendste zijn de leerstoelgroep Aquacultuur en Visserij en het voormalige rijksinstituut voor visserijonderzoek, het RIVO. In dit artikel legt Leo Nagelkerke, universitair docent bij de leerstoelgroep Aquacultuur en Visserij, uit waar zij zich zoal mee bezighouden

Vijveronderzoek vorm teen belangrijk onderdeel van het systeemwerk in Wageningen. De achtergrond waartegen het vijveronderzoek in Wageningen plaatsvindt wordt schetst

Enkele in Nederland veel voorkomende ziekten bij vissen van de afgelopen twintig jaar. Eel Virus European, Eel Virus European X, Herpesvirus van Paling, Infectieuze Hematopoietische Necrose, Infectieuze Pancreatische Necrose, Koi Herpes Virus, Snoekvirus, Spring Viremia of Carp, Virale Hemorrhagische Septicaemie en Vissen-TBC zijn daar enkele voorbeelden van

Ophoping van mest, voerresten en ander organisch materiaal kan in de vijverteelt tot waterkwaliteitsproblemen leiden. In het laboratorium van de Leerstoelgroep Visteelt en Visserij, Wageningen Universiteit, is de afgelopen jaren onderzoek gedaan naar de omstandigheden die de afbraak van mest, voerresten en ander organisch materiaal bepalen. Dit artikel vat enkele resultaten samen

Er worden enkele mondiale trends geschetst op het gebied van de productie van vis, schelp- en schaaldieren. Er is een groeiende vraag naar vis, schaal- en schelpdieren. De groei zit vooral in ontwikkelingslanden, waardoor het aandeel van de aquacultuurproductie in de ontwikkelde landen verder af zal nemen

Met het stijgen van de watertemperatuur in het voorjaar komt ook het metabolisme van de vis op gang. Veel vissoorten paaien bovendien in het voorjaar of de vroege zomer, dus ook hormonaal verandert er van alles. Dit hoort bij een natuurlijke gang van zaken maar geeft ook stress aan de vis. Stress is een basis voor ziekte. Welke ziekten kunnen we zoal aantreffen in de buitenvijver met het stijgen van temperatuur naar zomerse waarden?

De koi sector is bekend met verschillende ziekten van koi, zoals koi herpesvirus (KHV) en columnaris disease door Flavobacterium columnare. Dit najaar is echter een in Nederland nog niet eerder aangetoonde ziekte aangetroffen in koi: het koi sleepy disease (KSD). We gaan in dit artikel in op deze ziekte

In Nederland is de myxospore parasiet Myxidium giardi in mei 2005 in beeld gekomen bij palingen in fuiken op het IJsselmeer. Op palingkwekerijen in broedhuizen komt de parasiet doorgaans niet voor, wel in vijversystemen.

In 2010 vatte drie ondernemers het plan op om bij de Rotterdamse Fruithaven een loods en het erom heen gelegen rangeerterrein een landbouwkundige bestemming te geven. Het duurde tot 2012 voordat voldoende kapitaal en vergunningen waren geregeld en met de aanleg van Uit Je Eigen Stad begonnen kon worden. Inmiddels is er veel bereikt (waaronder een werkend aquaponics systeem met een inhoud van 125 m3) en worden groente, tilapia, Afrikaanse meerval, paddenstoelen en kippen in het eigen restaurant en in Rotterdam en omgeving verkocht. Maar de medewerkers van Uit Je Eigen Stad rusten niet en gaan door met het testen en proberen van verschillende gewassen, productiewijzen, producten, markten en evenementen. We bezochten het bedrijf en spraken met Ivo Haenen.

Wakker Dier voert de laatste weken actie tegen het onverdoofd slachten van vissen. Net als de kippen en varkens moeten de vissen worden verdoofd voor de slacht, vindt de actiegroep. Kan dat? De meeste kweekvis in Nederland wordt al verdoofd aan de slachtlijn, stellen Wageningse onderzoekers, maar de wilde vis uit de Noordzee nog niet. Om ook de schol en haring aan boord van het vissersschip verdoofd te kunnen slachten, is eerst meer onderzoek in het lab en op zee nodig.

Wakker Dier voert de laatste weken actie tegen het onverdoofd slachten van vissen. Net als de kippen en varkens moeten de vissen worden verdoofd voor de slacht, vindt de actiegroep. Kan dat? De meeste kweekvis in Nederland wordt al verdoofd aan de slachtlijn, stellen Wageningse onderzoekers, maar de wilde vis uit de Noordzee nog niet. Om ook de schol en haring aan boord van het vissersschip verdoofd te kunnen slachten, is eerst meer onderzoek in het lab en op zee nodig.

Antony Jesu Prabhu, P. (2015). Minerals in fish: does the source matter? PhD thesis. Wageningen University, The Netherlands.Minerals are a group of micro-nutrients essential to fish. Meta-analysis of literature data was performed to identify the appropriate response criterion to determine the mineral requirement of fish. The meta-analysis revealed that, vertebral mineral concentrations or specific enzyme activities provide stringent requirement estimates compared to weight gain. Dietary intake forms the major route of mineral supply to fish; however fish are also capable of acquiring dissolved minerals from the rearing water. Changes in the dietary composition or mineral concentration of rearing water could have an impact on the mineral balance in fish. In this thesis, high fat diets, diets devoid, or low in fish meal and rearing systems with high water mineral concentrations were studied for their impact on the mineral balance in rainbow trout or common carp. Increased available phosphorus levels were needed (0.4% vs. 0.8%) in high fat diets to improve whole body and vertebral mineralisation as indicated by ash, P and Ca concentrations. However, supplementing phosphorus to complete plant ingredient based diets negatively affected the absorption and utilisation of micro-minerals namely Zn, Cu and Se. In rainbow trout that received complete plant ingredient based diets, the endogenous loss of Zn was higher and of Cu was lower resulting in Zn depletion and Cu accumulation in the body. Further, the hepatic metabolism of Fe and Cu was affected in rainbow trout fed the plant ingredient based diets, possibly due to the alterations in bile or cholesterol metabolism. With regard to the minimal dietary levels required, supplementation of Zn and Se were required beyond the levels recommended by NRC (2011) to maintain body balance in rainbow trout and common carp when fed complete plant ingredient based diets. Common carp reared in recirculation aquaculture systems (RAS) with high concentration of minerals in the water was able to acquire and retain minerals from water. However, only in the case of Se, they were able to compensate for a part of the dietary requirement. On the whole, higher dietary levels of P and Ca are required in the diet of fast growing rainbow trout; dietary levels of Zn and Se have to be increased beyond present recommended levels in plant ingredient based diets for rainbow trout and common carp. Low water exchange RAS has multiple effects on the whole animal physiology of fish and requires further research for better understanding.

Seasonal floodplains are water bodies that retain water for 5-6 months during which they are suitable to grow fish and other aquatic animals. Out of 2.8 million ha of medium and deep-flooded areas, about 1.5 million ha are estimated to be suitable for Community-Based Fish Culture (CBFC). WorldFish had undertaken a five-year interdisciplinary action research project from 2005-2010 with the overall aim of enhancing the productivity of seasonally occurring floodwaters for the improved and sustained benefit of the livelihoods of the poor. My involvement in this project was as PhD Scholar from 2007-2009 for understanding the different and complex institutional arrangements and its overall impact of governing Community-Based Fish Culture in seasonal floodplains for the sustainable use and maximization of benefits to the targeted people of Bangladesh. Six seasonal floodplains in different areas of Bangladesh were selected under the action research project implemented by the Department of Fisheries in collaboration with the Bangladesh Agricultural Research Council and the Bangladesh Fisheries Research Institute. For the action research which is the subject of this thesis, three seasonal floodplains were selected in the Brahamaputra, the Padma and the Teesta River Basins located at Mymensingh, Rajshahi and Rangpur districts, respectively. Another three floodplains were selected as control sites in the same river basins located near to the projects sites. The control sites were included in the economic study (Chapters 4 and 5) only. All the six floodplains belong to two types of ownership categories: public floodplains surrounded by private lands. My thesis is broadly divided into a sociological and an economic part, mainly because of methodological differences. Chapter 2 and Chapter 3 discuss the institutional arrangements and the power and decision-making process of Community-Based Fish Culture management. Chapter 4 addresses the overall economic impact of technical and institutional arrangements of fish culture at both floodplain and household levels. We here employed a random effects model to estimate the impact of participation on fish income. Finally, in Chapter 5 the economic impact of community-based fish culture on expenditure inequality was measured at household level. In the sociological part, three project floodplains covered the different institutional arrangements for managing the floodplains and maximizing their benefits to different classes of beneficiaries. Power relations between the various key actors or stakeholders were assessed who were directly or indirectly involved in the floodplain, and decision making processes in co-management practices were also studied at different institutional levels. Sociological research methods and techniques including semi-structured interviews, Focus Group Discussions, informal discussions with key informants, and quantitative surveys were applied to gather data from Floodplain Management Committees, villagers and institutional stakeholders to investigate the use of the floodplain as a common property resource (CPR) and the processes of the formation of local institutions and organizations. For the economic analysis of Chapter 4 and Chapter 5, three project floodplains and three control floodplains were selected for comparing the impact of the intervention at beneficiary level and also community level. Household survey data includes a baseline survey on socioeconomic information, three months monitoring on seasonal and monthly basis at community and household levels, as well as an assessment of the floodplains’ natural resource systems. The seasonal survey covered the changes in input use for crop production, changes in quality of output from the agricultural land and the effects of the intervention on crop production. A monthly survey on the 1st and 15th day of the month was conducted to capture the household consumption pattern, especially the frequency and quantity of fish and meat consumption. Chapter 2 improves our understanding of the complex institutional relationships governing Community-Based Fish Culture in seasonal floodplains in Bangladesh. Formal institutional linkages between DoF, WorldFish Center and the Bangladesh Agricultural Research Council (BARC) played a key role in ensuring success. DoF is a government institution with establishments at different administrative levels. Institutional embedding of DoF through the Fishers Cooperatives (FMC) as implementing institutions appeared highly instrumental. Large numbers of people, including landless poor seasonal fishers, professional landowning fishers, and non-fishing landowners benefited from the successful implementation of the CBFC activities in the floodplains. The outcomes demonstrate a significant increase in income to all classes of beneficiaries through income sharing derived from their involvement in the fisheries cooperatives and fish culture. In case 2 and case 3 the floodplains under private ownership privately owned land is inundated during the monsoon season; these floodplains are similar in size, with comparable percentages of beneficiaries and similar numbers of communities surrounding the floodplains. However, the distribution of beneficiaries among the classes differs with more landowners than landless seasonal fishers benefitting. FMCs normally allow these non-members to access the floodplains, but only to harvest un-stocked fish using local gears, considering the importance of fishing to their livelihood. This means that the CPR character of the management by the FMCs shows a certain permissiveness or permeable boundary regarding landless non-members under strict spatial and temporal conditions. Regulation and conservation thus guarantee the availability of un-stocked small fish in the floodplains with a high catch by artisanal gears which results in higher incomes and related benefits to the poorer households. Households who own land or ditches in the floodplains do not depend on un-stocked fish as they can have ponds to trap and harvest fish obtained in the wild. Additionally, during the dry season, they may use land in lowland areas for crop production. Case 1 of the public floodplain surrounded by private lands differs most from the private floodplain cases. Here, the public area is leased out to fishers during the monsoon, including the private land owned by the affluent and politically influential stakeholders. The floodplain is larger than in the other two cases, but both the percentages of landless fishers and of landowners are lower, making the class of the landowning professional fishers the majority among the beneficiaries. Generally, the rules and regulations that apply to public and privately owned floodplains are written down in a Memorandum of Understanding between DoF and the individual FMC’s in a non-judicial construction. In their regular meetings the FMCs also document the everyday practices of the rules related to fish culture and management in the minutes that are distributed among its members. It appears that in the three cases, comparable rules and regulations for fish culture are applied to the public and to the private floodplains in operational rules, collective choice rule and constitutional rule. Benefit sharing of the fish production from the floodplains was agreed at the start of project activities by all stakeholders, but their commitment varied between the classes of beneficiaries and across the cases. A significant increase of income for different stakeholders was derived from their involvement in fish culture. In the public floodplain fishers received around 40% of net income increase and the landowners received almost 38% of net income increase, as they had to pay the lease money for the floodplain. But in private floodplain all classes of stakeholders deposited around 25% of their net income in a revolving fund. The fishers group got their income from the final harvesting of fish as they received 50% of the price of the harvest of un-stocked fish and 10-15% of the stocked fish. The landowners received 45-50% of income according to their land. The landless seasonal fishers had open access to the non-stocked fish during the monsoon. Finally, the users of the public as well as the private floodplains contributed a small portion of their income to social work, like the building of a mosque or a Hindu temple. Chapter 3 firstly assessed the power relations between the various key actors or stakeholders who were directly or indirectly involved in floodplain fisheries in the three sites. Secondly, their shifting power relations and decision making process in co-management practices were studied in the different institutional contexts of the three research sites during WorldFish project intervention. Instead of merely listing the institutions involved, we studied the actual power practices and decisions making processes between the stakeholders in the three cases to gain insight in the different governance models used in CBFC in Bangladesh. Existing co-management arrangements are characterized by unequal power distribution among the different actors, often resulting in the marginalization of the professional fishers and the landless poor fishers. I differentiated between two types of power in the management of floodplain aquaculture and stakeholder involvement, namely a) the power to create rules and decision making procedures, and b) the power to resolve disputes and ensure compliance. The Floodplain Management Committee (FMC) reviews the rules and regulations formulated by the government to complement the vision and roles of the institution, and if there is a need, modify them. Rules and regulations governing access to the public and privately owned floodplains were developed by the Department of Fisheries (DoF) and the FMC. A similar set of rules and regulations was applied to the public and the privately owned floodplains for fish culture. Most of the rules were derived from the national fisheries law. The rules and regulations that were applied to the floodplain were written down in a Memorandum of Understanding between DoF and FMC. Examples are rules and regulations about membership, leadership, boundary and access, allocation, penalties, input, and conflict resolution that were enforced for the management of community based-fish culture. Magistrate courts at local level in Bangladesh have the power to decide on penalties for offenders in case of violation of the Government Fisheries Act of 2010 (DoF 2013) in the management of fisheries and aquaculture including the floodplain; a range of penalties is stipulated in the Offences and Penalties paragraph of the Act. In addition, in the case of both public and private floodplains, leaders of customary organizations have the authority and power to confiscate illegal nets and penalize offenders by charging monetary fines. Governance in the context of Community-Based Fish Culture (CBFC) management addresses the dominancy of the land-owning group, informal sets of norms and traditions, and the social network and power relationships between stakeholders. In the public floodplain governance processes resulting in the formation of a responsive, accountable leadership and representative membership appeared vital for the success of CBFC. But, the establishment of successful CBFCs in public floodplains demands continuous institutional support from agencies such as the Department of Fisheries, because an increase in production and income also increases the risk of elite capture, and the possibility of an exploitative. In the private floodplain, there was no specific governance system in place to manage access and use of the floodplains during the wet season, as opposed to the dry months when the lands of the floodplain could be used by individual households for crop production. Thanks to greater accountability of the leaders, and more equal representation of the different stakeholders including active leadership and a supporting role of DOF, leadership problems were few and easily solved. Downward accountability was well established in addition to many efforts by the project. Chapter 4 examined the overall impact on households involved through the WorldFish project in community-based fish culture in seasonal floodplains, particularly with respect to fish production, consumption, and income generation. Qualitative as well as quantitative methods were deployed to examine the impact of Community-Based Fish Culture starting with a conceptual framework as to how positive impacts take effect. The overall fish production in the floodplains of the project appeared to have increased 274%. Due to project intervention introducing fish culture, 43% of the farmers used floodplain water to meet up irrigation needs instead of ground water and rice production increased by 18.9% for dry-season (Boro) rice and 28.9% for wet-season (Aman) rice in the project floodplain areas. Increased income is an important economic incentive for the expansion of community-based fish culture in Bangladesh. Over that period, average income from fish production increased to USD 240 for all beneficiaries involved in the project, which is 237% higher than the income of beneficiaries in the control group. Results of the random effects model show that project-involved households significantly increased their fish income compared to the households of the control sites. Furthermore, total household income increased to about USD 175 per household for those who participated in the WorldFish project. Fish availability increased in the project area from July to December. During these months approximately 68%-75% of the total fish consumption needs of the project beneficiaries could be fulfilled by the newly introduced fish culture in the floodplains. The consumption of nutritional food shows that per capita fish consumption of households in the project sites increased from 1.26 kg per capita per month in the baseline year to 2.31 kg per capita per month in 2009. Apart from the direct effect on household income and food consumption, CBFC intervention also created the opportunity for employment, backward linkage, and access to market to sell harvested fish. Indirect benefits of the community based fish culture include reduced conflict; improved social capital and greater cooperation in the community. Expenditure is a better measurement of welfare than income where most of the people are poor and struggle for food. In this study I therefore used data on expenditure instead of income. The results in Chapter 5 show that the CBFC project had a positive and significant impact on food expenditure, as well as on non-food (other basic needs) and overall total expenditure. The impact of CBFC on household expenditure and expenditure inequality was measured by using Propensity Score Matching (PSM) method and Gini decomposition. Results revealed that the overall average food expenditure per year per household (for panel estimation) increased due to participation in the CBFC project from USD 93 to USD 141. Project participants were able to spend significantly more on food compared to non-participants. In addition, expenditure on food was increasing year by year. Moreover, participant households were capable to spend more compared to non-participants on non-food items like cloth, health, education, housing, transport etc. (from USD 45 to USD 74 per year). This non-food expenditure also gradually increased per year. Finally, total household expenditure of CBFC project participants was between USD 134 and USD 215 per year higher than the total expenditure of control households, which implies a better livelihood of the households involved in the project. Gini index of total expenditure was found to be 0.34 and 0.40 for the CBFC project and control households respectively, which indicate that expenditure was equally distributed among households, but that it is more equally distributed among the CBFC households as compared to the control households. The expenditure inequality difference between the CBFC project and the control sites was 0.06, which implies that the CBFC management system helped to distribute total expenditure more equally among the surrounding communities. Policy advice For better management of the floodplain beels, the government may apply a similar policy for better utilization of the resources and for the economic benefits of the beneficiaries. Accountability, sustainable management of the floodplains, proper marketing of fish and equity in the distribution of benefits of the floodplains have proven to increase the productivity and ensure the accessibility of the poor and landless farmers, as long as elite capture is controlled. Taking all CBFC project lessons into consideration, the Bangladesh government could indeed make some changes to their floodplain /wetland policy in order to accommodate the poor fishers and the landless poor. Policy (re)formulation may be needed for the dissemination of the CBO-based fish culture approach to scale-up its impact. In order to establish the rights of the CBOs (under the leadership of fishers) there is a need for modification of the policy of leasing of public floodplains. The major issues to be included are to bring private and public floodplains under CBO management; to secure government support for the registration of the CBOs and the strengthening of the institution; to guarantee that CBOs obtain long term (10-15 years or more) lease of the public areas of the floodplains as priority; to support small infrastructure constructions in the outlet and inlets of the floodplains; and to develop a functional model for the scaling-up (influencing policy) and scaling-out of the CBO fish culture approach in Bangladesh. Future research To assess the effectiveness of the scaling-up of the innovation in Community-Based Fish Culture in public and private floodplains, using a CBO to CBO approach will have to be developed with the support and facilitation from formal institutions. This will be considered as the subject of future research.