Johan A.J. Verreth

Johan A.J. Verreth
Wageningen University & Research | WUR · Department of Aquaculture and Fisherie

PhD

About

465
Publications
98,809
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
11,436
Citations
Citations since 2017
62 Research Items
5447 Citations
201720182019202020212022202302004006008001,000
201720182019202020212022202302004006008001,000
201720182019202020212022202302004006008001,000
201720182019202020212022202302004006008001,000
Introduction
Johan A.J. Verreth is professor emeritus from the Department of Aquaculture and Fisheries, Wageningen University & Research.

Publications

Publications (465)
Article
Full-text available
With a sixth mass extinction looming and freshwater biodiversity declining at unprecedented rates, evaluating ecological efficacy of river restoration efforts is critical in combatting global biodiversity loss. Here, we present a comprehensive study of the functioning for fishes of 46 river restoration projects in the river Rhine, one of the world'...
Article
The cover image is based on the Review Article Optimization of aquaculture sustainability through ecological intensification in China by Shuang‐lin Dong et al., https://doi.org/10.1111/raq.12648 The cover image is based on the Review Article Optimization of aquaculture sustainability through ecological intensification in China by Shuang‐lin Dong et...
Article
Full-text available
White spot syndrome virus (WSSV), the etiological agent of white spot disease (WSD), is a significant pathogen affecting shrimp farming industry worldwide. White spot syndrome virus is a generalist virus mainly infecting decapod crustaceans. The aims of this review were to: (1) Re‐evaluate and update the status of reported WSSV host and vector spec...
Article
As the world's leading producer of farmed aquatic food products, China faces great uncertainty concerning the further sustainable development of its aquaculture industry due to high and increasing pressure from environmental and resource constraints. To realize truly sustainable development, it is imperative to establish an evaluation system that i...
Article
Full-text available
The large-scale degradation of riparian ecotones and of the connectivity between rivers and their floodplains has resulted in a drastic decline of rheophilic fish populations in European temperate lowland rivers. Recent river restoration projects have had variable success in effectively restoring these fish populations. Knowledge on nursery habitat...
Article
Full-text available
The kinetics of nutrients digestion and development of chyme characteristics in African catfish (Clarias gariepinus) were assessed in response to fishmeal hydrolysation and non-protein energy (NPE) sources. Four diets were formulated to contain starch or fat as NPE source, and fishmeal or hydrolysed fishmeal as protein source in a 2 × 2 factorial d...
Article
Full-text available
In this study, the effect of feeding frequency and its interaction with crystalline methionine supplementation level on performance, digestion, energy and nitrogen balances was assessed. The experiment had a 2 × 4 factorial design, testing two levels of crystalline methionine (Met) and four feeding frequencies. The two diets contained Met either ju...
Article
Full-text available
Apparent digestibility coefficients (ADC) of nutrients and individual amino acids (AA) for 13 feed ingredients as affected by feeding level were determined for African catfish, a species of economic importance in Africa. Results from two trials are reported. In each trial, ADC were determined using a reference diet and test diets with yttrium oxide...
Article
Full-text available
The addition of external carbohydrate in Pacific white shrimp (Litopenaeus vannamei) culture has shown positive effects on water quality and shrimp performance. However, this practice requires additional skills and labor, and therefore may not be widely adopted. This research investigated the potential to combine the carbon source and the feed in o...
Article
Full-text available
This study was conducted to estimate the methionine (Met) requirement of African Catfish (Clarias gariepinus). A basal diet was formulated to contain 32% crude protein, 12% lipids, and 0.44% cysteine using only protein from legume ingredients as intact protein. This diet was supplemented with graded levels of crystalline DL- methionine (0, 0.12, 0....
Article
Full-text available
Fish farmers utilize the reversibility of the bioconcentration process to depurate geosmin and other off- flavour causing chemicals from their fish by placing them in clean water just before harvest. To better understand and improve this process, we investigated effects of temperature and water exchange of depuration tanks on geosmin elimination fr...
Article
Full-text available
Using capture fishery‐derived fish oil and fishmeal in aquafeeds is unsustainable. This study mimicked semi‐intensive shrimp ponds, including primary producers, in mesocosm tanks. Fatty acid mass balances were computed to distinguish between diet‐based and primary production‐based LC‐PUFA contributions to shrimp (Litopenaeus vannamei) production an...
Article
In Pacific white shrimp culture, adding organic carbohydrate to the pond besides feed improves water quality and shrimp performance. While the feeding frequency has significant effects on shrimp production, how often carbohydrate should be added remains unknown. This research investigated the effects of carbohydrate addition frequency of 1, 3, and...
Article
Full-text available
The ecological efficacy of river restoration projects may change over time, resulting in the loss of their ecological function for targeted species. The goal of this study was to evaluate the rheophilic nursery function of restored floodplain channels over time, by analysing 30 years of monitoring data from 12 restoration projects in the lower rive...
Preprint
Full-text available
Aquaculture is the fastest growing food production industry in terms of annual growth rate and has become an important contributor in supplying essential macro-and micro-nutrients for the global population. However, there is a great deal of uncertainty in its further development due to the high and increasing pressure of environmental challenges an...
Article
Full-text available
This review investigates the performance and the feasibility of the integration of an algal reactor in recirculating aquaculture systems (RAS). The number of studies related to this topic is limited, despite the apparent benefit of algae that can assimilate part of the inorganic waste in RAS. We identified two major challenges related to algal inte...
Article
Full-text available
In biofloc technology carbohydrate is added to stimulate the biofloc growth, the latter helps to improve water quality, reduce the need for water exchange and may serve as natural shrimp feed. The large diversity among possible carbohydrate sources makes the selection of a suitable carbohydrate difficult. This study investigated how corn starch add...
Article
Full-text available
The effect of feeding during off-flavour depuration on the elimination of geosmin from muscle tissue (fillet) and ovaries as a model for caviar was assessed in Nile tilapia (Oreochromis niloticus) (mean ± SD weight of 185 ± 15.0 g). The experiment had a 2 × 4 factorial design with feeding level (starved or fed) and depuration time (24, 48, 72 and 9...
Article
Full-text available
Dietary non-starch polysaccharides (NSP) changes the nutrient digestibility and faecal characteristics in fish. This study assessed the effect of the type of dietary NSPs on fish production and the contribution of natural food to the total fish production in semi-intensively managed tilapia ponds. Twelve ponds, each divided into three equally-sized...
Article
Full-text available
This study tested the effect of two diets differing in carbohydrate to lipid (CHO:LIP) ratio (4.7 vs. 19.5 g/g) on the contribution of natural food and the total fish production in tilapia ponds. Eight ponds, each divided into three equally sized compartments, were assigned to one of the two diets, which differed in CHO:LIP ratio but had the same d...
Article
The objective of this study was to investigate the effect of the gas: liquid ratio (GLR) on carbon dioxide removal and heat loss across a forced-ventilated trickling filter (TF) used as bioreactor. The effect of 8 different GLRs (1.2–15.7) on carbon dioxide removal and heat loss from water passing a trickling filter were tested in random order. The...
Article
Full-text available
The study analysed the dose–response relationship between dietary viscosity and nutrient digestibility, faecal waste characteristics in striped catfish and the long‐term impacts of viscosity on performance of striped catfish. This was done in two experiments: Exp.1 lasted 29 days, in which six dietary viscosity levels were created by including diff...
Technical Report
Full-text available
This report provides a comprehensive assessment of existing and potential feed resources for improving aquaculture productivity in Bangladesh, Myanmar, Malaysia, Egypt, Nigeria and Zambia. These countries depend heavily on imports for their supply of quality feed ingredients. The viability and feasibility of ingredients for aquafeed production are...
Article
Full-text available
The present study assessed the effect of different feed ingredients on nutrient apparent digestibility coefficients (ADC), nitrogen/energy balance and morphology changes in the intestine of Nile tilapia; using a control diet and six test diets, in which the following six ingredients were included at 30%: hydrolysed feather meal (HFM), soybean meal...
Article
There is growing interest to understand the dietary P:E requirements for the supplemental feed used in tilapia pond culture where natural food contributes to production. In an on-farm trial, we tested the effect of lowering dietary P:E ratio on fish performance, pond nutrient utilization and economic benefit under two stocking densities and feeding...
Article
Full-text available
Sole fed commercial pellets develop a nutritional anaemia. This study assessed the impact of dietary B12 and taurine on the haematocrit (Hct) and haemoglobin (Hb) level and mineral absorption in anaemic sole. Anaemic sole was fed one of four diets. Diets were equal regarding mineral, amino acid and macronutrient composition and formulated, accordin...
Article
Full-text available
The impact of two dietary organic acids (OAs) on nutrient digestibility and intestinal morphology was determined in Nile tilapia under conditions of dissolved oxygen in the water: normoxia and hypoxia. Four diets designated as control (0 g/kg organic acid salt), KDF (2 g/kg potassium diformate), CAB (2 g/kg calcium butyrate) and their combination (...
Article
Full-text available
Nile perch (Lates niloticus), a main target for Lake Victoria's fisheries, shifts its diet from invertebrates to fish during its ontogeny. We combined stomach contents with stable isotopes to study these diet shifts in Mwanza Gulf, southern Lake Victoria. During four seasons between 2009 and 2011 we collected and analysed 6697 stomachs and 516 stab...
Article
When fish have only access to formulated feed, the optimal dietary protein to energy ratio (P:E) for tilapia ranges between 18 and 23 g.MJ−1. In pond culture, where natural foods complement administrated feed, increasing the carbon:nitrogen (C:N) ratio stimulates the natural food productivity. This study assessed if lowering the dietary P:E ratio (...
Article
Full-text available
Recirculating aquaculture systems (RAS) are becoming important for aquaculture due to land and water supply limitations and due to their low environmental impact. Bacteria are important in RAS as their role in nutrient recycling has been the main mechanism for waste removal in these systems. Besides bacteria, the presence of microalgae can benefit...
Article
Full-text available
We evaluated the effect of low pH and low and high total ammonia nitrogen (TAN) concentrations on the physiology, stress status and the growth performance of turbot in RAS. Two experiments were conducted. In Experiment 1, turbot (466 g) were grown at control (pH 7.5; TAN ~0.5 mg/L) or low pH and high TAN (pH 5.7; TAN ~50 mg/L) for 55 days. In Exper...
Article
There is a recognized need for mineralizing aquaculture-derived sludge in aquaponics systems in order to reduce waste production. Many recent studies of aquacultural waste treatment have focused only the production of biogas as opposed to the potential for mineralization of nutrient-rich sludge. Upflow anaerobic sludge blanket (UASB) reactors provi...
Article
Full-text available
The experimental set-up of this study mimicked recirculating aquaculture systems (RAS) where water quality parameters such as dissolved oxygen, pH, temperature, and turbidity were controlled and wastes produced by fish and feeding were converted to inorganic forms. A key process in the RAS was the conversion of ammonia to nitrite and nitrite to nit...
Data
Water quality data (min, max, mean, and standard deviation). (PDF)
Data
Three way repeated measure analysis of variance of total ammonia nitrogen (TAN), nitrite (NO2-N), and nitrate (NO3-N) concentration (mg L-1) in recirculating aquaculture systems. The results compare between factors algae (with algae (+A) and without algae (-A)), location (fish, algae and nitrification), stressor (with stressor (+S) and without stre...
Data
Repeated measure analysis of variance of apparent total ammonia nitrogen (TAN) conversion rate (mg L-1 day-1) and apparent nitrite (NO2-N) conversion rate (mg L-1 day-1) in recirculating aquaculture systems. The results compare between factors algae (with algae (+A) and without algae (-A)), and stressor (with stressor (+S) and without stressor (-S)...
Data
pH changes in recirculating aquaculture system (RAS) with algae (+A) and without algae (-A). (TIF)
Data
Curves based on Chao1 (richness analysis) at a sequencing depth of 315930. Samples are labeled with factors “algae”- with algae (+A), without algae (-A); “location”- fish (Lf), algae (La) and bio-filter (Lb) tanks; “day”- a day before stress (d-1), 20 days after stress (d20) and “stressor”- stressed (+S) and not stressed (-S). (TIF)
Data
Microbiota differences based on operational taxonomy units (OTU) and cluster of orthologous genes (COG). (PDF)
Data
Percentages of predicted sequences by cluster of orthologous genes (COG). Samples are labeled with factors “algae”- with algae (+A), without algae (-A); “location”- fish (Lf), algae (La) and bio-filter (Lb) tanks; and stressor- stressed (+S) and not stressed (-S). (TIF)
Data
Operational taxonomy unit (OTU) dissimilarity of bacterial community between stressed (+S) and non-stressed (-S) recirculating aquaculture system (RAS). The graph shows the top 10% OTU which contributed to the total dissimilarity as given by SIMPER analysis. A number of percentage (%) written next to the identity of OTU denoted the % of contributio...
Data
Relative abundance of nitrifying bacteria. Bacteria which were able to perform autotrophic nitrification (Nitrosomonadaceae, Nitrospira) or heterotrophic nitrification and denitrification (Rhodococcus, Chryseobacterium, Bacillus, Acinetobacter, and Pseudomonas) identified in the recirculating aquaculture systems with (+A) and without algae (-A) a d...
Data
Percentage (%) of daily water replacement from recirculating aquaculture system on days after pH drop was applied. (TIF)
Article
Full-text available
Vietnamese pangasius farming needs to produce efficiently to compete in world markets. This study investigates the input- and output-specific technical inefficiency of Vietnamese pangasius farmers. First, we used a Russell-type (input–output) directional distance function to estimate the input- and output-specific technical inefficiency. Second, we...
Article
Full-text available
Stable isotope analyses and derived population-level metrics were used to quantitatively analyse spatial and seasonal heterogeneity in the fish trophic dynamics in relation to environmental variables in Mwanza Gulf, Lake Victoria (Tanzania). The fish community in Lake Victoria, including the top predator Nile perch, is generally omnivorous with a h...
Article
We examined the influence of prey density and fish size on prey consumption in common sole (Solea solea L.) foraging on buried ragworm Alitta virens (Sars) (formerly known as Nereis virens (Sars)). The tested prey densities of 0.8, 2.2, 4.3 and 6.5 individuals dm⁻² were exposed to common soles of either 100 g or 300 g. At each prey density common s...
Article
The present study compares the influence of signals released from fish (common sole, Solea solea L.) and conspecifics on the feeding behavior of the ragworm Alitta virens (Sars) (formerly known as Nereis virens (Sars). Experimental tanks stocked with ragworms were connected to a donor tank by a tube to allow the transfer of water born signal molecu...
Article
Full-text available
The technical efficiency of randomly sampled pangasius farms in the Mekong Delta of Vietnam was estimated using data envelopment analysis, and factors affecting technical and scale efficiency were examined with bootstrap truncated regression. The mean technical efficiency score assuming variable returns to scale was 0.84. The technical efficiency o...
Article
The bioconcentration of waterborne geosmin in rainbow trout, Oncorhynchus mykiss (Waldbaum) was assessed. Fifty rainbow trout with a mean (SD) weight of 226.6 (29.0) g and lipid content of 6.2 (0.6) % (w/w) were exposed to geosmin in static water for 0, 2, 4, 6, 8, 12, 24, 36, 48 and 120 hr, with one tank containing five fish for each exposure peri...
Article
This study determined prey consumption in common sole as a function of prey size (0–0.5, 1–1.5, 2–2.5 and 4–5 g), sediment thickness (20 cm and 2 cm) and fish size (50 g, 125 g or 300 g). Prey consumption (in numbers of prey eaten per fish per day) was reduced with increasing prey size and sediment thickness, and was increased with increasing fish...
Article
Full-text available
The ingredients’ particle size and dietary viscosity may alter digestion, performance and faecal waste management of fish. This study aimed to assess the effect of grinding screen sizes of feed ingredients and dietary viscosity on digestibility, faecal waste and performance of striped catfish (Pangasianodon hypophthalmus, Sauvage, 1878). The experi...
Article
Full-text available
To assess the potential for improving sustainability and efficiency in an important Vietnamese finfish culture, we quantified sustainability indicators for 2 downstream and 2 upstream 3 to 4 m deep ponds for striped catfish Pangasianodon hypophthalmus (Sauvage, 1878) production along the Mekong River, Vietnam. The resources used per kg fish produce...
Article
Full-text available
Incorporation of microalgae in recirculating aquaculture systems (RAS) would absorb the inorganic nitrogen and phosphorus, thus potentially contributing to water purification. Immobilization or entrapment of microalgae cells in spherical gels could be a method to incorporate microalgae in the RAS. Filamentous microalgae are presumed to suit the imm...
Article
This study established that geosmin depuration from European eel is not affected by the water renewal rate of depuration tanks. A general fish bioaccumulation model extended with terms that account for effects of tank water renewal rate and system losses of chemicals, predicted strong effects of the water renewal rate of depuration tanks on geosmin...
Article
Full-text available
Rates of dark respiration and net photosynthesis were measured on six replicate clonal fragments of the stony coral Galaxea fascicularis (Linnaeus 1767), which were incubated under twelve different combinations of dissolved oxygen (20%, 100% and 150% saturation), dissolved carbon dioxide (9.5 and 19.1 μmol L(-1)) and water flow (1-1.6 cm s(-1) vers...
Article
Price transmission in international supply chains is important to ensure that price premiums paid by consumers for environmental sustainability labels are transmitted upstream to farmers. This facilitates investment in sustainable aquaculture systems. This study analyzes the price transmission from the international retail stage to the Vietnamese f...
Article
This study compares the effect of food type (formulated diet vs. natural food) and fish size on protein and energy utilization efficiencies for growth in common sole, Solea solea (L.). Replicate groups of common sole (mean initial body weight ± SD was 45.7 g ± 2.1 and 111.2 g ± 4.2) received the diets at five (natural feed) or four (formulated diet...
Article
Recirculation aquaculture systems (RASs) operated at low water exchange rates are known to accumulate minerals in the water. This study examined the dietary mineral requirement and metabolism in common carp reared in RAS of contrasting water exchange rates. Two independent RAS (water exchange rates, 70 vs. 2000 L/kg feed) and five experimental diet...
Article
The accumulation of steroids released by fish in recirculating aquaculture systems (RAS) may potentially influence their physiology and behavior. The present study examined the release rate of cortisol and testosterone by Nile tilapia, Oreochromis niloticus, and their accumulation in six identical lab scale RAS operated at different water exchange...
Article
Full-text available
The exposure of fish to environmental free-living microbes and its effect on early colonization in the gut have been studied in recent years. However, little is known regarding how the host and environment interact to shape gut communities during early life. Here, we tested whether the early microbial exposure of tilapia larvae affects the gut micr...
Article
Steroids accumulate in recirculating aquaculture system (RAS), although explanatory factors for such accumulation are still poorly explored. This study investigated the effect of water exchange rate and pH in six replicated RAS on the concentration of the stress hormone cortisol in rainbow trout blood plasma and in the holding water and of the sex...
Article
The present study was undertaken to evaluate the individual and combined effects of oxygen concentration and diet composition on the growth, nutrient utilization and intestinal morphology of Nile tilapia (Oreochromis niloticus). Two recirculating aquaculture systems were used to create the difference in oxygen concentration: normoxia (6.9 mg.L-1) a...
Article
For Nile tilapia, the energetic value of non-starch polysaccharides (NSP) was compared to starch. It was assessed if carbohydrate type (NSP vs. starch) affected the energetic utilization for growth (KgDE) and the energy requirements for maintenance (DEm). Eighteen groups of fish were assigned in 2x3 factorial design: two diets, with either a high N...
Article
Full-text available
This study aims to analyze the economic feasibility of recirculating aquaculture systems (RAS) in pangasius farming in Vietnam. The study uses a capital budgeting approach and accounts for uncertainty in key parameters. Stochastic simulation is used to simulate the economic performance of medium and large farms operating with a traditional system o...
Article
In response to increasing concerns about sustainable production, a growing number of European customers expect seafood products to be certified, e.g. by ASC certification. A possible answer to achieve environmental sustainability of Vietnamese pangasius farming is to apply recirculating aquaculture systems (RASs) at the farm. However, RAS requires...
Article
Sole fed commercial pellets suffers from a nutritional anaemia. The hypotheses tested are: (1) the nutritional anaemia in sole fed commercial pellets is caused by an iron deficiency; (2) the assumed iron deficiency is due to inadequate absorption of iron; (3) an increase in absorption due to a higher bioavailability of heme or iron chelates will al...