Research Institute For Aquaculture No1

Vietnam

Research Institute For Aquaculture No1

Vietnam
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In V.V.,University of The Sunshine Coast | O'Connor W.,Port Stephens Fisheries Institute | Sang V.V.,Research Institute For Aquaculture No1 | Van P.T.,Research Institute For Aquaculture No1 Ria1 | Knibb W.,University of The Sunshine Coast
Aquaculture | Year: 2017

Oyster aquaculture is a new and fast growing sector in Vietnam, but confusion exists about the identity of the species presently under culture, whether they are Pacific oysters (Crassostrea gigas), Portuguese oysters (Crassostrea angulata), hybrids thereof, or other species. This study was carried out to identify which oyster or oysters are most commonly cultured in Vietnam and, additionally, once the species identity was resolved, to assess three farmed Vietnamese stocks for levels of genetic variation and suitability for captive breeding programs. To resolve the taxonomy issues, we searched for nucleotide differences (characteristic attributes) in published mitochondrial DNA cytochrome c oxidase subunit 1 (COI) sequences that, for the first time, would categorically separate and distinguish in particular C. angulata from C. gigas. On review of 300 published haplotypes of C. angulata and C. gigas based on a 293 bp nucleotide-fragment of published COI sequences, we found that there were five distinct nucleotides that are categorically different between C. angulata and C. gigas and that could be considered as diagnostic nucleotides. Using these five diagnostic nucleotides, we confirmed that the samples from northern Vietnam are C. angulatam, not C. gigas. Similarly, we identified other oyster species in Vietnam from Nhatrang as C. sikamea and C. madrasensis. DNA microsatellite data (following) can also support understanding of the taxonomy, directly by comparing allele types and frequencies between putative species, but also indirectly because as nuclear DNA, microsatellite genotypes may reveal if hybridization is occurring (as evidenced by deviations from Hardy-Weinberg equilibrium). No evidence, considering Hardy-Weinberg deviations, for interspecific hybridization was found. To address the diversity issues, three hatchery bred populations of C. angulata were screened for allelic variation at nine DNA microsatellite loci. All three lines had high allelic diversity, moderate effective population sizes (Ne), and little evidence of kinship, which, by precedent with other hatchery bred highly fecund oyster species, is a little unexpected. It is speculated that local hatchery practises may involve sharing stock among hatcheries which then may contribute to the maintenance of moderate to high levels of diversity during hatchery reproduction of this highly fecund species. © 2017 Elsevier B.V.


Nguyen N.H.,University of The Sunshine Coast | Hamzah A.,National Prawn Fry Production and Research Center | Thoa N.P.,Research Institute For Aquaculture No1
Frontiers in Genetics | Year: 2017

The extent to which genetic gain achieved from selection programs under strictly controlled environments in the nucleus that can be expressed in commercial production systems is not well-documented in aquaculture species. The main aim of this paper was to assess the effects of genotype by environment interaction on genetic response and genetic parameters for four body traits (harvest weight, standard length, body depth, body width) and survival in Red tilapia (Oreochromis spp.). The growth and survival data were recorded on 19,916 individual fish from a pedigreed population undergoing three generations of selection for increased harvest weight in earthen ponds from 2010 to 2012 at the Aquaculture Extension Center, Department of Fisheries, Jitra in Kedah, Malaysia. The pedigree comprised a total of 224 sires and 262 dams, tracing back to the base population in 2009. A multivariate animal model was used to measure genetic response and estimate variance and covariance components. When the homologous body traits in freshwater pond and cage were treated as genetically distinct traits, the genetic correlations between the two environments were high (0.85-0.90) for harvest weight and square root of harvest weight but the estimates were of lower magnitudes for length, width and depth (0.63-0.79). The heritabilities estimated for the five traits studied differed between pond (0.02 to 0.22) and cage (0.07 to 0.68). The common full-sib effects were large, ranging from 0.23 to 0.59 in pond and 0.11 to 0.31 in cage across all traits. The direct and correlated responses for four body traits were generally greater in pond than in cage environments (0.011-1.561 vs. -0.033-0.567 genetic standard deviation units, respectively). Selection for increased harvest body weight resulted in positive genetic changes in survival rate in both pond and cage culture. In conclusion, the reduced selection response and the magnitude of the genetic parameter estimates in the production environment (i.e., cage) relative to those achieved in the nucleus (pond) were a result of the genotype by environment interaction and this effect should be taken into consideration in the future breeding program for Red tilapia. © 2017 Nguyen, Hamzah and Thoa.


Thoa N.P.,Research Institute For Aquaculture No1 | Hamzah A.,National Prawn Fry Production and Research Center | Nguyen N.H.,University of The Sunshine Coast
Animal Reproduction Science | Year: 2017

The present study examines genetic variation and correlated changes in reproductive performance traits in a red tilapia (Oreochromis spp.) population selected over three generations for improved growth. A total of 328 breeding females (offspring of 111 sires and 118 dams) had measurements of body weight prior to spawning (WBS), number of fry at hatching (NFH), total fry weight (TFW) and number of dead fry (NDF) or mortality of fry including unhatched eggs at hatching (MFH). Restricted maximum likelihood (REML) analysis in a multi-trait model showed that there are heritable genetic components for all traits studied. The heritability for WBS was very high (0.80). The estimates for traits related to fecundity (NFH, TFW) and survival (NDF) were low and they were associated with high standard errors. Genetic correlations of WBS with other reproductive performance traits (NFH, TFW and NDF) were generally positive. However, NFH was negatively correlated genetically with TFW. As expected, body measurements during growth stage exhibited strong positive genetic correlations with WBS. The genetic correlations between body traits and reproductive performance (NFH, TFW, NDF) were not significant. Correlated responses in reproductive traits were measured as changes in least squares means between generations or spawning years. Except for WBS that increased with the selection programs, the phenotypic changes in other reproductive traits observed were not statistically significant (P. >. 0.05). It is concluded that the selection program for red tilapia has resulted in very little changes in reproductive performance of the animals after three generations. However, periodic monitoring of genetic changes in fecundity and fitness related traits such as NDF or MFH should be made in selective breeding programs for red tilapia. © 2017.


Le D.V.,Auckland University of Technology | Le D.V.,Research Institute For Aquaculture No1 | Alfaro A.C.,Auckland University of Technology | Ragg N.L.C.,Cawthron Institute | And 2 more authors.
Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology | Year: 2016

Geoduck clams (Panopea spp.) are the longest-lived and largest deep burrowing bivalve. Their unique morphology allows them to live buried in the sediment at depths of up to 1 m. The endemic New Zealand geoduck (Panopea zelandica Quoy and Gaimard, 1835) has recently been identified as a potential species for aquaculture. However, very little is known about the biology and physiology of this entirely subtidal geoduck species. Currently, the New Zealand geoduck fishery relies entirely upon wild harvests, but farms are expected to emerge as cultivation protocols are established. A key step in the optimization of cultivation procedures is the identification of optimal temperature and food rations. One method for establishing thermal optima is to identify the temperature window that supports the widest aerobic scope: the degree to which metabolic rate can be increased to support elevated activity demands. Thus, we investigated the aerobic scope for activity at five different temperatures representative of typical environmental conditions (8, 11, 15, 19, and 23 °C) for juvenile and young adult P. zelandica. Clearance rate was also measured at all temperatures. Comparisons of aerobic scope for activity and clearance rates between size classes revealed that juvenile geoducks had a narrower thermal optimum than young adults (15–19 versus 11–19 °C, respectively). Temperatures higher than 19 °C resulted in a reduction of aerobic scope for activity and clearance rate for both juvenile and young adults, which may lead to reduced performance and elevated mortality. These findings provide the first measures of aerobic scope in P. zelandica, a key step towards a meaningful understanding of the ecophysiology of this unusual species. © 2016 Springer-Verlag Berlin Heidelberg


Phan V.T.,Copenhagen University | Ersboll A.K.,University of Southern Denmark | Nguyen T.T.,Vinh University | Nguyen K.V.,Research Institute For Aquaculture No1 | And 3 more authors.
Emerging Infectious Diseases | Year: 2010

Residents of the Red River Delta region of northern Vietnam have a long tradition of eating raw fish. Fish-borne zoonotic trematodes (FZTs) are estimated to infect ≈1 million persons in Vietnam. It remains uncertain at what stages in the aquaculture production cycle fish become infected with FZTs. Newly hatched fish (fry) from 8 hatcheries and juveniles from 27 nurseries were therefore examined for FZT infection. No FZTs were found in fry from hatcheries. In nurseries, FZT prevalence in juveniles was 14.1%, 48.6%, and 57.8% after 1 week, 4 weeks, and when overwintered in ponds, respectively. FZT prevalence was higher in grass carp (p<0.001) than in other carp species. Results show that nurseries are hot spots for FZT infections in fish. Thus, sustainable FZT prevention strategies must address aquaculture management practices, particularly in nurseries, to minimize the risk of distributing infected juveniles to grow out ponds and, subsequently, to markets for human consumption.


Bui T.N.,Research Institute for Aquaculture No1 | Pham T.T.,Research Institute for Aquaculture No1 | Nguyen N.T.,Research Institute for Aquaculture No1 | Nguyen H.V.,Vietnam Academy of Science and Technology | And 2 more authors.
Parasitology Research | Year: 2016

Preliminary findings of a high prevalence of Clonorchis sinensis in wild-caught fish in a North Vietnam reservoir (Thac Ba reservoir, Yen Bai Province) prompted a longitudinal epidemiological study of fish infections. Monthly collections of fish from September 2014 to August 2015 were processed for recovery of metacercariae; 1219 fish, representing 22 species, were examined. Seven species were infected with C. sinensis metacercariae. Four species, Toxabramis houdemeri, Hemiculter leucisculus, Cultrichthys erythropterus, and Culter recurvirostris, had high prevalence (31.1 to 76.7 %); metacercarial intensities ranged from 3.9 to 65.7 metacercariae/fish. A seasonal variation of C. sinensis prevalence was observed in T. houdemeri. Variation in intensity of infection occurred in C. erythropterus and H. leucisculus. Intensity and prevalence of C. sinensis in the most highly infected species, T. houdemeri, varied by fish size; prevalence was higher in fish weighing more than 3 g, and intensity was higher in fish weighing more than 5 g. The distribution of metacercariae in the body region of T. houdemeri was significantly higher in the caudal fin (14.7 metacercariae/g), compared to the body and head regions (0.7 and 1.4 metacercariae/g, respectively). Further epidemiological investigations on C. sinensis in this reservoir region should include assessing the relative risk of the different fish species for humans based on the latter’s food preferences, and the prevalence of C. sinensis in the community. The snail intermediate host(s) in the reservoir should also be identified along with the ecological factors influencing its exposure to C. sinensis eggs and its subsequent transmission of cercariae to fish. Also needed are investigations on the relative importance of wild and domestic reservoir hosts as sources of egg contamination of the reservoir. © 2016 Springer-Verlag Berlin Heidelberg


Clausen J.H.,Copenhagen University | Madsen H.,Copenhagen University | Murrell K.D.,Copenhagen University | Van P.T.,Research Institute For Aquaculture No1 | And 5 more authors.
Emerging Infectious Diseases | Year: 2012

Worldwide, >18 million persons were infected with fish-borne zoonotic trematodes in 2002. To evaluate the effectiveness of interventions for reducing prevalence and intensity of fish-borne zoonotic trematode infections in juvenile fish, we compared transmission rates at nurseries in the Red River Delta, northern Vietnam. Rates were significantly lower for nurseries that reduced snail populations and trematode egg contamination in ponds than for nurseries that did not. These interventions can be used in the development of programs for sustained control of zoonotic trematodes in farmed fish.


Nhu V.C.,Ghent University | Dierckens K.,Ghent University | Nguyen H.T.,Research Institute For Aquaculture No1 | Hoang T.M.T.,Vinh University | And 4 more authors.
Aquaculture | Year: 2010

Cobia (Rachycentron canadum) is a very fast growing species. This can only be achieved if sufficient amounts of feed are provided from early larval development onwards. In this study, we examined the effects of early co-feeding and different co-feeding formulated diets on growth, survival and vitality of cobia larvae and juveniles. Two experiments were conducted to test the possibility of early co-feeding of the two formulated diets for cobia larvae (8-18 dph) and one experiment was conducted to compare the effect of three formulated diets for cobia juveniles (20-38 dph). During the larval stage, two formulated diets: Proton ® and an experimental diet (INVE, Belgium) were used along with live food from eight days post hatch (dph) and 13dph compared to 18dph as the control. Results from the study indicated that early co-feeding of Proton ® from eight dph had a significantly positive effect on growth (P<0.05), but not on survival and stress resistance in a salinity stress test (P>0.05) of cobia larvae. In the second trial, no significant difference (P>0.05) was detected between all treatments in terms of growth, vitality and survival. However, high mortality occurred in the treatment with the experimental diet as of 12dph. The study suggested that early co-feeding of Proton ® to cobia larvae from eight dph is possible and research on the appropriate nutritional composition of weaning diets needs to be addressed. In the juvenile stage, three formulated diets, i.e. the experimental diet, Proton ® and NRD ® (INVE Aquaculture NV) were evaluated for growth performance and survival of early cobia juveniles (20-38dph). The diets were manually introduced from 22dph at a feeding frequency of every 2h until satiation, while feeding of enriched EG Artemia was maintained until 30dph. Average length and weight of the 38-dph juveniles fed the experimental diet were significantly higher (P<0.05) compared to larvae fed Proton ® and NRD ®. However, the coefficient of size variation as well as the cumulative stress index in a salinity challenge test was not significantly different (P>0.05). Survival in the Proton ® treatment was the lowest, while no significant difference was evident between the experimental diet and NRD ® treatments. The mortality rate of all three treatments had two peaks: one at the beginning of the experiment and one when live food feeding was discontinued. This result indicates that the nutritional requirements of cobia are age-dependent and prolongation of live food co-feeding during weaning may be necessary. The higher DHA/EPA ratio in the experimental diet can be a clue for the improvement of growth and survival of cobia during the weaning stage. © 2010 Elsevier B.V.


Mai H.,Research Institute For Aquaculture No1 | Fotedar R.,Curtin University Australia | Fewtrell J.,Curtin University Australia
Aquaculture | Year: 2010

Effluent water from intensive prawn aquaculture systems typically has a high concentration of dissolved nutrients such as nitrogen and phosphorus. A study was conducted for 42days to investigate the nutrient flow in a system where brown seaweed (Sargassum sp.) was integrated into western king prawn (Penaeus latisulcatus) culture. Three treatments namely, western king prawn monoculture (5.48±0.29g), Sargassum sp. monoculture and seaweed/prawn integrated culture were tested for nutrient flow among feed, water and species cultured. The results showed that by integrating seaweed into prawn culture, the concentrations of total ammonium nitrogen (TAN), nitrite-nitrogen (NO2 -) and nitrate-nitrogen (NO3 -), dissolved inorganic nitrogen (DIN), total nitrogen (TN), phosphate (PO4 3-) and total phosphorus (TP) were significantly lower (p<0.05) in the integrated culture system than in the prawn monoculture (p<0.05) and remained within non-toxic limits for the duration of the study. In addition, the integration of Sargassum sp. with western king prawn culture did not significantly alter the nitrogen and phosphorus conversion rates from feed into prawns (approximately 17.69-18.99 and 13.79-14.47%, respectively). The specific growth rate (SGR) and survival rate of the prawns in integrated treatment did not significantly differ (p>0.05) from the prawn monoculture. The mean biomass of Sargassum sp. in integrated culture increased at the rate of 3.16±0.74% g day-1 after 7days of the study, which was significantly higher than in the monoculture system (5.70±0.82% g day-1). The results suggest that integrating Sargassum sp. into western king prawn culture can benefit prawn farming by assisting in the maintenance of optimum water quality and thereby, reducing environmental impacts on surrounding areas. © 2010.


PubMed | Research Institute For Aquaculture No1 and University of The Sunshine Coast
Type: | Journal: Scientific reports | Year: 2016

This study assessed whether selection for high growth in a challenging environment of medium salinity produces tilapia genotypes that perform well across different production environments. We estimated the genetic correlations between trait expressions in saline and freshwater using a strain of Nile tilapia selected for fast growth under salinity water of 15-20ppt. We also estimated the heritability and genetic correlations for new traits of commercial importance (sexual maturity, feed conversion ratio, deformity and gill condition) in a full pedigree comprising 36,145 fish. The genetic correlations for the novel characters between the two environments were 0.78-0.99, suggesting that the effect of genotype by environment interaction was not biologically important. Across the environments, the heritability for body weight was moderate to high (0.32-0.62), indicating that this population will continue responding to future selection. The estimates of heritability for sexual maturity and survival were low but significant. The additive genetic components also exist for FCR, gill condition and deformity. Genetic correlations of harvest body weight with sexual maturity were positive and those between harvest body weight with FCR were negative. Our results indicate that the genetic line selected under a moderate saline water environment can be cultured successfully in freshwater systems.

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