Aquaculture In China Research Articles

Eco-efficiency of freshwater aquaculture in China: an assessment considering the undesirable output of pollutant emissions

Eco-efficiency of freshwater aquaculture in China: an assessment considering the undesirable output of pollutant emissions

A high-density genetic linkage map and QTL mapping for growth related traits in grass carp (Ctenopharyngodon idella)

Grass carp (Ctenopharyngodon idella), one of the most important freshwater food fish, has made a great contribution to freshwater aquaculture in China. Though a consensus linkage map of grass carp has been reported, the low marker resolution limited its application in fine mapping quantitative trait loci (QTL) of commercially important traits. In this study, a high-density linkage map was constructed based on a full-sib F1 family of grass carp, which was further used for mapping QTL for five growth related traits: body weight (BWE), body length (BL), body width (BWI), body height (BH) and fatness (FN). This high-density genetic map was constructed with 3979 SNPs, consisting of 24 linkage groups (LGs). The total length of the linkage map was 1752.742 cM, with an average marker resolution of 0.44 cM. QTL mapping analysis detected two significant and 19 suggestive QTL for the five morphometric traits, distributed on 8 LGs. The phenotypic variations explained of these QTL ranged from 7.2% to 32.8%. Finally, comparative genomic analysis revealed that 23 out of the 24 LGs of grass carp showed high synteny with 23 chromosomes of zebrafish. Taken together, the high-density linkage map and the 21 growth-related QTL, provide valuable genomic resources for both marker-assisted selection (MAS) and comparative genomic studies in grass carp and its related species.

Effects of hypoxia and reoxygenation on gill remodeling, apoptosis, and oxidative stress in hypoxia-tolerant new variety blunt snout bream (Megalobrama amblycephala).

Blunt snout bream plays an important role in freshwater aquaculture in China, but the development of its culture industry has been restricted by increasing hypoxia problem. Through the breeding of wild blunt snout bream populations (F0), a hypoxia-tolerant new variety (F6) was obtained. In this study, the new variety was stressed under low oxygen concentration (2.0mg·L-1) for 4 and 7days, the morphological structure of the gill tissue showed a striking change, the interlamellar cell mass (ILCM) volume reduced significantly (P < 0.05), and the lamellar respiratory surface area enlarged significantly (P < 0.05), compared to normoxic controls. After 7days of oxygen recovery, gill remodeling was completely reversed. Additionally, the TUNEL-positive apoptotic fluorescence signals increased in the gills exposed to hypoxia up to 4 and 7days; the apoptosis rate also increased significantly (P < 0.05). Under 4 and 7days of hypoxia stress, the expression of anti-apoptotic gene Bcl-2 in the gills downregulated significantly (P < 0.05), with the significantly (P < 0.05) upregulated expression of pro-apoptotic gene Bad. Furthermore, under hypoxia stress, the activity or content of oxidative stress-related enzymes (superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and glutathione (GSH)) in gill tissue increased to varying degrees compared to normoxic controls. These results offer a new perspective into the cellular and molecular mechanism of hypoxia-induced gill remodeling in blunt snout bream and a theoretical basis for its hypoxia adaptation mechanism.

PacBio Isoform Sequencing and Illumina RNA Sequencing Provide Novel Insights on Responses to Acute Heat Stress in Apostichopus japonicus Coelomocytes

Significant increases in global sea surface temperatures are expected with climate change and may cause a serious challenge for marine organisms cultured in aquatic environments that are characterized by short and long-term fluctuations in water temperatures. Apostichopus japonicus, a sea cucumber with high nutritional value and pharmacological properties, is an important economic species that is widely raised in aquaculture in China. In recent years, continuous extreme high temperatures (up to 30°C) have occurred frequently in summer leading to mass mortality of sea cucumbers cultured in semi-open shallow regions seriously restricting the sustainable development of sea cucumber aquaculture. In the present study, we combined RNA-seq and PacBio single-molecular real-time (SMRT) sequencing technology to unveil the potential mechanisms of response to acute heat stress in A. japonicus coelomocytes. A total of 1,375 differentially expressed genes (DEGs) were identified in a comparison of control and 48 h heat stress (HS) groups. Pathway enrichment analysis indicated that nine important pathways induced by HS were significantly enriched (q-value &amp;lt; 0.05) and mostly fell into four classes: folding, sorting, and degradation, immune and infectious diseases, signal transduction, and post-transcriptional regulation. Among them, all 41 genes connected with protein processing in endoplasmic reticulum were significantly up-regulated, and 12 of these were selected and validated via qPCR. Furthermore, changes in alternative splicing (AS) were also identified in sea cucumbers following HS. A total of 1,224 and 1,251 differential alternative splicing (DAS) events were identified using splice junction counts (JC only) and reads on target and junction counts (JCEC) as the input for rMATS in CO-HS comparison. We further found that the RNA splicing-related genes were enriched in the spliceosome pathway and showed DAS in control versus heat-stressed animals. In particular, we compared and confirmed that the hsfs1 gene, the master regulator of the heat shock response, showed differentially spliced exons in response to HS. This is the first comprehensive study showing that transcriptional and post-transcriptional (AS) controls are involved in the acute heat stress response of sea cucumber coelomocytes and provides novel insights into the molecular mechanisms of echinoderm adaptation to environmental stress.

Optimization of aquaculture sustainability through ecological intensification in China

AbstractAs 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 integrates social, economic, environmental and resource criteria, and optimizes aquaculture systems through a holistic approach. Here, we used analytical hierarchy processes combined with expert judgment and objective data to assess the sustainability of 10 major aquaculture production systems (APSs) in China. Based on the evaluation results, we propose the ecological intensification of aquaculture systems (ELIAS), rationally integrating anthropogenic inputs with aquaculture ecosystem services, to improve the sustainability of APSs. The holistic evaluation system and ELIAS are fundamental and critical for the future development of aquaculture in China and globally.

Analysing ecological carrying capacity of bivalve aquaculture within the Yellow River Estuary ecoregion through mass-balance modelling

As the largest aquaculture producer in the world, China is facing the challenge of maintaining sustainability while continuing to develop the aquaculture industry to meet socio-economic needs. Models of trophic structure and energy flow can be used to analyse ecological carrying capacity in order to determine whether a large and rapidly increasing aquaculture industry potentially puts sustainable development at risk. The Yellow River Estuary ecoregion in Shandong Province, China, is an ecologically important region, with extensive bivalve aquaculture that is increasing rapidly at an overall growth rate of 4% annually during recent decades. A trophic mass-balance model was used to analyse the ecological carrying capacity of bivalve aquaculture in this ecoregion. The biomass of cultured bivalves is currently 13.3 t km-2 and could be increased to 62.0 t km-2 without exceeding the ecological carrying capacity. Zooplankton are a key factor limiting the ecological carrying capacity and represent a sensitive functional group within the food web system in this ecoregion. At the ecological carrying capacity of cultured bivalves in the Yellow River Estuary ecoregion, harvests would amount to 353.2 t km-2 yr-1 or a total of 4.2 million t yr-1 in this region. If the current average rate of growth in aquaculture in China is maintained, under cautious development, the biomass of cultured bivalves would reach half of the estimated ecological carrying capacity (31.0 t km-2) after 20 yr. This implies that there is capacity for sustainable development of bivalve aquaculture under current environmental conditions.

The Economic and Technical Efficiency of Yellow Cat Fish (Pelteobagrus Fulvidraco) Production in China

China’s yellow catfish (Pelteobagrus fulvidraco) productions has undergone a rapid growth since the year 2000 and Its Productions increased high ranging from 50, 000 tones to 114, 000 tons in 2007, and to over 300, 000 tons in 2014 by far the largest producer in the world. Yellow catfish (Pelteobagrus fulvidraco) are freshwater species native to Chinese waters. The aim of the study is to provide a better understanding on the present trends in the economic and technical efficiency of Yellow catfish (Pelteobagrus fulvidraco) production in China and learn from the Chinese wider experiences as a guide to the developing countries as they strive to develop their aquaculture sectors. The method of the study employed secondary data information collected from the reputable sources such as Food and Agriculture Organization of the United Nations, Nanjing Agriculture University-electronic library, China fisheries year books and annual reports including other relevant websites browsed containing some valuable information about Chinese aquaculture status and the data gathered was analyzed. Freshwater aquaculture in China has made a concerted effort to uplift culture practices on selected, high-valued, indigenous fish species. Currently yellow catfish has well established seed production technology, feed production, and efficient culture technology systems. It’s economically preferred by many consumers both in the local markets as well as international markets particularly by the south-eastern Asian countries like Japan and Korea. Despite the economic importance of yellow catfish species in the aquaculture sector, there is still limited information on its economic and technical efficiency production. Thus, this review paper highlights the economic and technical efficiency of yellow catfish production performances and focus on identifying critical matters that can support and improve yellow catfish productions in China as well as in the developing countries.

Efficiency in Chinese Large Yellow Croaker Aquaculture: Implication for Sustainable Aquaculture in China

Aquaculture supply from China has been a remedy to meet the growing global demand for seafood in the last decades. However, output growth has decreased dramatically in China in the 2000s. Previous literature focuses on the ecosystem problems arising in intensive farming in China. In this study, we used stochastic production analysis (SPA) to estimate the technical efficiency of Chinese large yellow croaker farming, which provides implications for impediments to the sustainable development of Chinese aquaculture. Data were collected from 430 large yellow croaker farmers in nine farming areas located along the coastline of southeastern China. The technical efficiency of large yellow croak farming is estimated to be 0.829, suggesting that farming is operated close to the production frontier with a maximal margin of 17% for improvement under the current technology. It further suggests that Chinese aquaculture growth is geared by conventional factors, expansion of fishing sites, and intensive farming, and is not sustainable under the constraint of farming areas and environmental problems in China. For the sustainable development of Chinese aquaculture, it is necessary to adopt new technology through innovation. The family-based farming model is a hinder to adopting new technology that requires systematic significant investment. Large-scale industrialized farming based on research and new technology development thus should be a modern trend in the future.

The total factor productivity index of freshwater aquaculture in China: based on regional heterogeneity.

Continuously improving freshwater aquaculture efficiency will promote the sustainable development of freshwater aquaculture, which is crucial to ensure aquatic food supply. In particular, measuring the total factor productivity (TFP) of freshwater aquaculture to find ways to improve its efficiency is of great significance to sustainable development of freshwater aquaculture industry. Therefore, based on directional distance function, this paper constructs a meta-frontier Malmquist index (MMI) model by considering the regional heterogeneity to evaluate the TFP of freshwater aquaculture of China from 2004 to 2019. The results show that (1) from the perspective of time, TFP fluctuated significantly from 2004 to 2012, while after 2013, TFP remained around 1 with small fluctuation. In other words, freshwater aquaculture in China began to maintain a relatively negative state of development. (2) From a regional point of view, this study found that freshwater aquaculture TFP of inland region is better than the TFP of coastal region. (3) From the decomposition index, the variation of freshwater aquaculture TFP was driven by the combined effect of technology change (TC) and technical efficiency change (EC). In addition, the decomposition index efficiency shows that the technical efficiency decreases and the management efficiency changes little. (4) The gap of freshwater aquaculture technology in coastal areas is very small, and close to the optimal technical level. While in inland region, on the contrary, there is more room for improvement. According to the above empirical results, this paper finally gives some policy suggestions to improve the TFP to ensure the sustainable development of freshwater aquaculture.

Isolation and Identification of an Efficient Aerobic Denitrifying Pseudomonas stutzeri Strain and Characterization of Its Nitrite Degradation

Nitrogen pollution in water bodies is becoming increasingly serious, and how to remove nitrogen from water bodies economically and effectively has become a research hotspot. Especially in recent years, with the gradual expansion of aquaculture in China, the content of nitrite and other nitrogen-containing substances in water bodies has been increasing, which inhibits the growth of farm animals and is one of the causes of eutrophication in water bodies. In this study, a strain of bacteria was isolated from the sludge of an aquaculture fishpond and identified as Pseudomonas stutzeri, which can efficiently degrade nitrite. After continuous domestication in nitrite mixed solution, the nitrite nitrogen reduction capacity of P. stutzeri was significantly improved. Univariate experiments aiming to optimize the degradation conditions indicate that the optimal culture conditions for strain F2 are: medium with a carbon source of sodium succinate; C/N of 18; pH of 8; culture temperature of 28 °C; and shaking speed of 210 rpm in the shaker. Under the optimal culture conditions, the NO2−-N concentration of the culture solution was 300 mg/L, and the nitrite removal rate reached 98.67%. Meanwhile, the results of the nitrogen balance test showed that the strain converted 6.1% of the initial nitrogen into cellular organic nitrogen and 62.3% into gaseous nitrogen.

Sulfamethoxazole and Enrofloxacin Antibiotics Affect Primary Productivity of Phytoplankton in Fishery Environment

The antibiotics sulfamethoxazole (SMZ) and enrofloxacin (ENF) are commonly used in aquaculture in China, but their effects on the primary productivity of phytoplankton are unclear. On the basis of the fishery drug use standards (SMZ, 100 mg kg−1 d−1; ENF, 15 mg kg−1 d−1), these antibiotics were put into culture ponds to observe their effects on the phytoplankton community and primary productivity. The results showed that the changes in phytoplankton species at SMZ and ENF sites were different. At the ENF sites, Bacillariophyta species increased from 7 to 9, euglenophyta from 8 to 12 and cyanophyta from 11 to 9. Chlorophyta species at the SMZ sites increased from 10 to 15 and euglenophyta from 7 to 4. SMZ and ENF significantly promoted the number of cyanophyta (p &amp;lt; 0.05). The promoting effect of SMZ was more obvious than that of ENF. SMZ was more effective than ENF in promoting cyanophyta. The maximum number of cyanophyta at SMZ sites was 52.39 million L−1, and the concentration of SMZ was positively correlated with the number of cyanophyta. The maximum number of cyanophyta at ENF sites was 33.13 million L−1, and the promoting effect of low concentrations was more significant than that of high concentrations. Both SMZ and ENF promoted increased phytoplankton biomass, consistent with the residual time of the antibiotics in the aquaculture environment. The greatest biomass at the SMZ sites was 129.31 g m−³, and that at the ENF sites was 117.85 g m−³. The changes in the α diversity index showed that both SMZ and ENF led to a decrease in phytoplankton biodiversity, and that SMZ was more harmful to it. There were significant differences in the Shannon–Wiener, Pielou and Simpson indexes of the SMZ sites within groups (p &amp;lt; 0.05). The β diversity index showed that both antibiotics could change the phytoplankton habitat, but the effect of ENF on the habitat was recoverable, while that of SMZ prevented its restoration. These data will be valuable in protecting the ecological environment of fisheries and ensuring the safety and stability of fishery aquatic ecosystems.

Phenotypic and Genetic Characterization of Flavobacterium psychrophilum Recovered from Diseased Salmonids in China.

ABSTRACTFlavobacterium psychrophilum, the etiological agent of bacterial coldwater disease (BCWD) and rainbow trout fry syndrome, causes great economic losses in salmonid aquaculture worldwide. Recent molecular studies have uncovered important epidemiological and ecological aspects of this pathogen; however, such data are lacking for F. psychrophilum populations affecting aquaculture in China. Herein, F. psychrophilum phenotype, genotype, and virulence were characterized for isolates recovered from epizootics in multiple salmonid aquaculture facilities across China. Thirty-one F. psychrophilum isolates, originating from four provinces and three host fish species, were predominantly homogeneous biochemically but represented 5 sequence types (STs) according to multilocus sequence typing (MLST) that belonged to clonal complex CC-ST10 or 3 newly recognized singleton STs. PCR-based serotyping classified 19 and 12 F. psychrophilum isolates into molecular serotypes 1 and 0, respectively, showing an obvious relationship with host species. Antimicrobial susceptibility analysis via broth microdilution revealed reduced susceptibility to enrofloxacin, flumequine, and oxolinic acid, moderate susceptibility to gentamicin, erythromycin, and florfenicol, and variable susceptibility to ampicillin and oxytetracycline. In vivo challenge experiments confirmed the ability of two representative Chinese F. psychrophilum isolates to induce typical signs of BCWD and mortality in 1-year-old rainbow trout (Oncorhynchus mykiss). Findings collectively demonstrate (i) that BCWD outbreaks in China studied thus far are caused by F. psychrophilum lineages that are common on other continents (e.g., CC-ST10) and others that have not been reported elsewhere (e.g., ST355, ST356, ST357), (ii) that F. psychrophilum molecular serotypes distinguish isolates from different host fish species, even within STs, and (iii) reduced F. psychrophilum antimicrobial susceptibility against compounds used for BCWD control in China.IMPORTANCE Flavobacterium psychrophilum causes substantial economic losses in salmonid aquaculture worldwide. Although this bacterium is also believed to be a disease source in China, published reports of its presence do not yet exist. Herein, F. psychrophilum was linked to multiple disease outbreaks in several salmonid aquaculture facilities within four Chinese provinces, and polyphasic characterization revealed that most isolates were genetically distinct from strains recovered on other continents. Analyses further revealed the predominating molecular serotypes, antimicrobial susceptibility profiles, and pathogenic potential of two representative recovered isolates. Collectively, the results presented here provide important data on the epidemiology and disease ecology of F. psychrophilum in China and pave the way for targeted prevention and control methods to be pursued in the future.

Whole-genome sequencing and antimicrobial resistance analysis of multidrug-resistant Aeromonas veronii strain JC529 from a common carp

Aeromonas veronii can cause infections in humans and a wide variety of aquatic and terrestrial animals as well as causing serious economic losses in aquaculture worldwide. Aeromonas veronii strain JC529 was isolated from an infected common carp in a fish pond in Jilin Province. In this study, we identified the multidrug resistance genes and traced the source of the strain in order to lay the foundation for research on the resistance mechanisms of other Aeromonas isolates. The isolated strain was sequenced using PacBio RS II and Illumina HiSeq 4000 platforms. Corrected reads were assembled using Celera and Falcon software and genes were predicted using Glimmer software. Seven databases were used for general function annotation. Virulence factors and resistance genes were identified based on the core data set in the VFDB and ARDB databases. Concurrently, 68 publicly available A. veronii genomes (including A. veronii JC529) were compared to reveal the clustering relationship of JC529. Aeromonas veronii strain JC529 has a circular chromosome of 4 834 659 bp with a GC content of 59.64%, including 4264 protein-coding genes, 2 prophages, 482 virulence factors and 27 antibiotic resistance genes, indicating that strain JC529 is a multidrug-resistant strain. The phylogenetic tree showed that strains JC529 and NS, PDB, AG5.28.6 and VCK1 appear to be inherited from a common ancestor and affect aquaculture in China and Greece. Strain JC529 is a multidrug-resistant A. veronii strain and has been inherited from a common ancestor with Greece.

Identification of the Specific Spoilage Organism in Farmed Sturgeon (Acipenser baerii) Fillets and Its Associated Quality and Flavour Change during Ice Storage.

Hybrid sturgeon, a popular commercial fish, plays important role in the aquaculture in China, while its spoilage during storage significantly limits the commercial value. In this study, the specific spoilage organisms (SSOs) from ice stored-sturgeon fillet were isolated and identified by analyzing their spoilage related on sensory change, microbial growth, and biochemical properties, including total volatile base nitrogen (TVBN), thiobarbituric acid reactive substances (TBARS), and proteolytic degradation. In addition, the effect of the SSOs on the change of volatile flavor compounds was evaluated by solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). The results showed that the Pseudomonas fluorescens, Pseudomonas mandelii, and Shewanella putrefaciens were the main SSOs in the ice stored-sturgeon fillet, and significantly affect the odors by changing the volatile compounds in the sturgeon. Compared with the fresh sturgeon, the appreciable increase of polycyclic aromatic hydrocarbons and tetramethyl-pyrazine might be the spoilage indicators of the sturgeon contaminated by P. fluorescens; the appreciable increase of 1-octen-3-ol and (z)-2-penten-1-o might be the potential marker of the sturgeon contaminated by P. mandelii; and the appreciable increase of 1-(3,3-dimethylbicyclo [2.2.1] hept-2-yl)-ethanon and butylated hydroxytoluene were associated with S. putrefaciens. This study reveals the relationship between the SSOs and flavor changes in sturgeon fillets, which will contribute to the sturgeon preservation and shelf-life extension.

Metabolic and transcriptional disruption of American shad (Alosa sapidissima) by enrofloxacin in commercial aquaculture

Antibiotics, including enrofloxacin (ENR), are widely used for bacterial disease treatment in aquaculture in China, resulting in their discharge into various aquatic environments. Therefore, researchers have focused their attention on the harmful effects of antibiotics on aquatic animal metabolism. To understand the impacts of ENR on the metabolism of cultured American shad, the guts of these fish were sampled to test the toxicity of ENR through the combined results of metabolomics and transcriptomics analyses. In this study, adult American shad were exposed to ENR (200 mg/kg) for 30 days. The results showed that ENR could significantly (p< 0.05) increase the body weight of American shad. ENR exposure also contributed to the dysregulation of intestinal metabolism (approximately 49 metabolites and 963 genes). Multiomics analyses of the responses indicated that the specific metabolic dysregulation caused by ENR affects many signaling pathways, such as the glycolysis/gluconeogenesis and pentose phosphate pathways, which are known to be linked with body weight gain through protein and lipid accumulation. In conclusion, ENR treatment affected the metabolic system in the gut of American shad. The transcriptomics and metabolomics analysis results provide essential data for evaluating antibiotic hazards in the guts of aquatic organisms.

Characterization of peroxisome proliferator-activated receptor at different stages of development of intestine, liver, spleen, pancreas and posterior kidney of the loach (Misgurnus anguillicaudatus)

The loach is one of the most important fish species in aquaculture in China. The study of peroxisome proliferator-activated receptors (PPARs) will be essential for the determination of the functional role of the PPARα and PPARγ in loach fish. We used immunohistochemistry for PPARα and PPARγ at some stages of development beginning from the age of 1 month till the age of 15 months. Our result indicated that the expression of PPARα and PPARγ was found in; columnar cells lining intestinal folds, hepatocytes, blood sinusoids in the liver, pancreatic islets, pancreatic acini, the whole spleen and epithelial cells lining renal tubules of the kidney. The expression pattern of both PPARα and PPARγ was low at the age of one month, then reach its highest level at the age of 2 months. Then it declines at the age of 5 months. Then it re-increase at the age of 7 months and became low in older ages. The expression of PPARα was higher in comparison with PPARγ.

Cover Image

The cover image is based on the Review Article Kelp aquaculture in China: A retrospective and future prospects by Zi‐Min Hu et al., https://doi.org/10.1111/raq.12524. image

Transcriptomics analysis of the infected tissue of gibel carp (Carassius auratus gibelio) with liver myxobolosis infers the underlying defense mechanisms from the perspective of immune-metabolic interactions

Liver myxobolosis, caused by Myxobolus wulii severely prevents the sustainable development of gibel carp (Carassius auratus gibelio) aquaculture in China. More insights into the host-parasite interaction will undoubtedly help to develop potential solutions to control this myxobolosis. Liver is an important organ to perform immunological and metabolic functions, changes of gene expression profile involved in fish liver against the local myxosporean infection, however, remain unknown. Here, a comparative transcriptomic analysis of severely infected and mildly infected liver from the same fish individuals, liquefying liver from the just died fish and control liver from the uninfected fish was conducted to investigate the possible involved molecular responses in the liver against the M. wulii infection. Upregulated differentially expressed genes (DEGs) were predominantly involved in adaptive immune responses, including the anti-inflammatory responses resulted from the synergism of Th1, Th17 and Treg cells, and antibody responses mediated by B cells. Downregulated DEGs were mainly involved in metabolic processes. Furthermore, 10 representative DEGs possibly involving in the immune-metabolic interactions were downregulated in the affected liver, demonstrating that the possible synergic mechanism of the suppression of metabolic activities and the facilitation of anti-inflammatory responses occurred in the infected liver. Combining the significant downregulation of cytoskeleton-related genes and upregulation of cell size-related genes, the histopathological, transmission and scanning electron microscopic analysis, it can be suspected that M. wulii is of intracellular infection. This is the first study to elucidate the molecular mechanism of immune-metabolic interactions underlying the fish liver myxobolosis, which will deepen the knowledge of the fish-myxospoean dialogue.

Development and application of monoclonal antibody against IgM of hybrid snakehead ( Channa maculata ♀ × Channa argus ♂)

Hybrid snakehead (C. maculate ♀ ×C. argus♂) culture has become an important aquaculture in China. However, severe disease caused by bacterial and viral infections resulted in enormous economic losses in the recent years. The effective disease control strategies have not been developed due to limited understanding of the immunology of this species so far. In this study, monoclonal antibodies (mAb) against serum immunoglobulin M (IgM) purified from hybrid snakehead was developed by stimulating mice, of which spleen cells were fused with myeloma cells to generate stable and effective antibody-producing hybridoma cells. The mAb clone number named as 1C3-1–12 and the mAb was further screened successfully using an indirect enzyme-linked immunosorbent assay (iELISA). Western blot analysis showed that the mAb 1C3-1–12 can specifically react with the heavy chain of IgM. There were no cross-reactions with sera from three other teleosts. Meanwhile, the mAb 1C3-1–12 can effectively detect serum IgM levels of hybrid snakehead and its evolutionally closely related species. Moreover, the mAb 1C3-1–12 was found to exclusively recognize the IgM+ B cells of hybrid snakehead by indirect immunofluorescence assay (IFA). Collectively, we developed a useful and specific monoclonal antibody against serum IgM from hybrid snakehead and will be an important immunological tool for better understanding the function of the immune system of hybrid snakehead. It may lie as a foundation for the establishment of diagnosis of disease and the development of effective vaccine.

Intensification, regulation and diversification: The changing face of inland aquaculture in China

Trends in aquatic food consumption were matched against farm production surveys within Hubei province and compared to official production data and statistics. Surveys showed that consumer tastes were changing to a much broader aquatic food menu as their spending power increased. Traditional aquaculture species were becoming less profitable due to reduced profit margins as input costs increased and consumption preferences changed. Consequently, many producers were diversifying their production to meet local demand. Some farmers were also de-intensifying by reducing commercial aquafeed inputs and reverting to more traditional methods of dyke-crop culture to optimise trade-offs between input costs and labour, and manage their risk more effectively. In addition, analysis of local data showed that wholesale changes were occurring to aquaculture production as environmental protection legislation took effect which reduced the growing area for carps considerably.