Litopenaeus Vannamei Research Articles

Developing Flowcharts for Hazard Analysis in Seafood Retail: Critical Control Point Verification

Background: Implementing Hazard Analysis and Critical Control Point (HACCP) management across the supply chain is promoted globally to ensure the safety of marine food products due to their rapid quality deterioration. However, many seafood retail stores deviate from adopting these practices. Therefore, in this study, we aimed to create a flowchart based on HACCP and validate it in retail stores. Methods: Chub mackerel (Scomber japonicus), scallops (Patinopecten yessoensis), and whiteleg shrimp (Litopenaeus vannamei) specimens were purchased from a supermarket from August to December 2020. The handling information of these products from receipt to sales was obtained to prepare an HACCP plan for retail stores. Groups adhering to and deviating from flowchart conditions were categorized as Critical Control Point (CCP)-compliant and CCP-deviant, respectively. Four samples of each product for each condition were analyzed. Bacterial viability was evaluated using the flat agar culture method. Escherichia coli and Vibrio parahaemolyticus were detected using the Brilliant Green-Lactose-Bile and material point methods, respectively. Product freshness was assessed by determining K-values using High-Performance Liquid Chromatography. Results were compared using Student’s t-test. Results: At elevated storage temperatures, bacterial growth rates were higher in chub mackerel and whiteleg shrimp than those in scallops. E. coli was not detected in any sample, whereas V. parahaemolyticus was detected in scallops and whiteleg shrimp but not in chub mackerel. CCP-deviant refrigerated scallops had increased V. parahaemolyticus counts; however, it did not differ between the frozen scallop and whiteleg shrimp. K-values increased more rapidly in CCP-deviant chub mackerel, whiteleg shrimp, and refrigerated scallops, but not in frozen scallops. Inadequate temperature control during display and sale markedly deteriorated the quality of marine products. Conclusion: Setting CCPs for marine food product display and sale while controlling temperature can preserve product quality. The flowchart created in this study can be broadly used for marine retail stores.

Integrating short- and full-length 16S rRNA gene sequencing to elucidate microbiome profiles in Pacific white shrimp (Litopenaeus vannamei) ponds.

Despite their immense economic value as a key aquaculture species, the production of Pacific white shrimp (Litopenaeus vannamei) faces significant challenges from intensive farming practices and disease outbreaks. Routine microbial profiling for disease surveillance could be a promising approach to anticipate and control disease outbreaks. To achieve this, accuracy in microbial profiling in shrimp ponds is crucial for enabling targeted action and prevention. Extensive documentation emphasizes that, beyond biological factors (related to the host, diet, or health status during the rearing period), technical elements, including sequencing techniques significantly influence bacterial community profiling. This study investigated the influence of short- and long-read sequencing of 16S rRNA genes on the microbial profiles in shrimp intestines, water, and sediments. The origin of the samples (intestine or environmental) in shrimp culture ponds primarily drove the observed differences in core microbial species. The ecological niches accounted for 56% of bacterial community variations in culture ponds. Both sequencing approaches showed consistent results in identifying higher-rank taxa and assessing alpha and beta diversity. However, at the species level, full-length 16S rRNA gene sequences provided better resolution than V3-V4 sequences. For routine microbial profiling in shrimp culture ponds, our study suggests that short-read sequences were sufficient for determining overall bacterial community.IMPORTANCEThis interdisciplinary study investigated the influence of sequencing techniques on bacterial communities profiling within Pacific white shrimp (Litopenaeus vannamei) ponds. By integrating aquaculture, microbiology, and environmental science, we revealed the role of ecological niches and factors like salinity and pH on microbiota diversity and composition in shrimp intestines, pond water, and sediment. Additionally, we compared the taxonomic resolution using partial versus full-length 16S rRNA gene sequences, highlighting the value of longer amplicons for precise identification of key taxa. These findings provide novel insights into microbial dynamics underlying environmental effects in shrimp aquaculture. Comprehensive characterization of the pond microbiome could lead to management strategies that promote shrimp health and productivity. Furthermore, the potential of a multi-omics approach for integrating complementary data streams to elucidate environment-microbiome-host interactions was highlighted.

Comparison of growth curves of the Pacific white shrimp, Penaeus vannamei Boone, 1931 (Decapoda, Penaeidae) reared in earthen ponds with three different water sources

Abstract The growth of the Pacific white shrimp, Penaeus vannamei was analysed with data from nine earthen ponds in three aquaculture farms located at the mouth of the Gulf of California in the state of Sinaloa, Mexico. Each farm has a different source of water supply: marine, estuarine-freshwater, and estuarine-hypersaline. Growth was estimated with a multi-model approach using five versions of the Schnute model. The parametrization was done with maximum likelihood as an objective function, and observing the variance criterion. The best model was selected via the Bayesian information criterion. The Schnute model reproduced the Von Bertalanffy model in the estuarine-freshwater conditions; the Logistic model in the estuarine-hypersaline situation; and the Gompertz model in the case of the marine water source. Differences in growth curves were corroborated via the Kimura ratio test. The difference in water quality was most evident in the factor salinity. The best performance was obtained with the estuarine-freshwater water source. The results support the hypothesis that postlarvae and juveniles exhibit better growth in brackish water than when supplied from a marine water source.

Effects of zinc-supplemented diets on growth, survival, and immune responses of the Pacific white shrimp, Penaeus vannamei Boone, 1931 (Decapoda, Dendrobranchiata)

Abstract The objective of this study was to investigate the effects of zinc (Zn)-supplemented diets on the growth, survival, and immunological indices of juvenile Pacific white shrimp, Penaeus vannamei. Four experimental diets were prepared and offered, which were: a non-supplemented basal diet (T1), a diet supplemented with organic Zn at 10 mg/kg (T2), a diet supplemented with organic Zn at 15 mg Zn/kg (T3), and a diet supplemented with inorganic Zn at 45 mg/kg (T4). In the 30-day feeding trial, specific growth rate, weight gain, and survival were significantly higher in shrimp fed T3 diets than in those fed T1 or T2. There were no significant differences in total haemocyte counts observed among the juvenile P. vannamei treated with Zn diets. In addition, dietary Zn supplementation significantly increased phagocytic activity of juvenile P. vannamei. Overall, these results indicate that appropriate dietary Zn has beneficial effects on growth, survival, and immune responses of juvenile Pacific white shrimp.

Sustainability of pacific white shrimp culture strategies during a regional outbreak of white spot syndrome virus

The present study evaluated economic, environmental and social sustainability of three production strategies of Pacific white shrimp (Litopenaeus vannamei) during a regional outbreak of white spot syndrome virus. The strategies mainly differed by stocking densities (92, 14, 8 larvae.m-2; D92, D14, and D8, respectively), fertilizer inputs, and other general management. Each dimension of sustainability was evaluated using sets of indicators. The D14 and D8 strategies showed greater economic feasibility than D92 because of the reduced operational costs and investments to buy post-larvae and feed. All strategies showed moderate environmental sustainability but had weakened economic and social sustainability due to the virus. The D14 and D8 strategies received the highest overall sustainability index. The D92 was the most environmentally favorable management strategy and had a social tendency. In general, shrimp mariculture performed with a high initial stocking density cannot guarantee the return of invested capital. The lower density strategies were economically feasible due to the high prices paid per kilogram of shrimp as a function of the higher individual average weight. However, economic feasibility of these two strategies coincided with low creation of employment opportunities and income, decreased social sustainability, and increased environmental impact.

Prophenoloxidase-activating system plays a crucial role in innate immune responses to Enterocytozoon hepatopenaei infection in shrimp Litopenaeus vannamei

The microsporidian Enterocytozoon hepatopenaei (EHP) is an emerging pathogen that causes high economic losses in shrimp industry. The knowledge on shrimp's immune response to EHP infection to properly handle this outbreak is poorly understood. The prophenoloxidase (proPO)-activating system is an important invertebrate innate immune systems that produces melanin and toxic reactive intermediates against invading pathogens. In this study, we investigated the role of the proPO-activating system during EHP infection in the Pacific white shrimp Litopenaeus vannamei. The expression of proPO-activating system-related genes was highly responded to the EHP infection and the hemolymph PO activity was significantly increased and tightly regulated during the infection. The melanization products, generated by the proPO activation, exhibit in vitro cytotoxicity effect on the EHP spores and inhibit spore germination. Suppression of the proPO-activating system by RNA interference significantly decreased hemolymph PO activity and resulted in increased EHP copy number and reduced expression of several genes in the JAK/STAT and Toll signaling pathways as well as antimicrobial peptides. Furthermore, suppression of the proPO system also reduced hemocyte adhesion and encapsulation of the EHP spores. These results demonstrated that the proPO system plays a vital role in reducing EHP infectivity and cross-talks with other humoral and cellular responses to coordinately defend the EHP infection.

Monitoring the Quality of Vannamei Shrimp (Litopenaeus vannamei) in Traditional Ponds in the Regencies of Lamongan and Gresik, as Suppliers for Fisheries Companies in East Java

Vaname shrimp (Litopenaeus vannamei) is one of Indonesia's leading fisheries commodities. Lamongan and Gresik districts are one of the largest vaname shrimp producers in East Java. This research was conducted to determine differences in the growth of vanami shrimp, differences in the quality of vanami shrimp in terms of color, absolute weight, absolute length, and differences in methods of cultivating vanami shrimp in Rejosari Village, Lamongan Regency and Pandanan Village, Gresik Regency. This research was conducted in April-May 2024 using 4 ponds (2 in Lamongan and 2 in Gresik). The methods used are qualitative and quantitative methods, measuring the color of vanami shrimp using a color reader, testing weight and length using the t-test to determine significant values ​​between the 2 locations, differences in methods of cultivating vanami shrimp using interviews with farmers. The results of this study showed that the color quality of vaname shrimp, A (Rejosari Village, Lamongan) in the 1st replication (pond A1) and (pond A2) doc k2 30-doc to 65 showed quite good color values ​​except for pond A in the 1st replication (pond A1). The results of the absolute weight t-test are 0.30 > 0.05, while for the absolute long t-test it is 0.94 > 0.05. The results of interviews with farmers showed differences in the feed used, farmers A1 and A2 used traditional feed in the form of cassava which was grated and then dried, the artificial feed used for ponds A1 and A2 was (multi super feed). Meanwhile, in ponds B1 and B2, traditional feed was used in the form of steamed leftover rice and corn, the artificial feed used for ponds B1 and B2 was (karka).

Comparative analysis of transcriptomics and metabolomics provides insights into the mechanisms of VPAHPND invasion and hepatopancreatic damage in Litopenaeus vannamei

Acute hepatopancreatic necrosis disease (AHPND) poses significant threats to the global shrimp farming industry; however, its molecular mechanisms remain largely unknown. Previous research has primarily focused on comparisons between infected and non-infected states, limiting our understanding of VPAHPND mechanisms. We integrated transcriptomic and metabolomic analyses to investigate the pathogenic mechanism underpinning AHPND in highly vulnerable post-larvae (PL) stage shrimp. By comparing shrimp infected with VPAHPND, those infected with non-VPAHPND, and uninfected shrimp (controls), we identified different VPAHPND infection responses, including significant cytoskeleton and metabolic reprogramming changes. Specifically, VPAHPND infection disturbed lipid, glutathione, and bile acid metabolism, while a key regulatory factor Farnesoid X Receptor (FXR) in these pathways was down-regulated. These findings suggest that VPAHPND manipulates host metabolism to enhance infectivity, leading to severe and irreparable hepatopancreas damage. Our study highlights the molecular interactions between VPAHPND and shrimp, and provides potential targets to mitigate the impact of AHPND in aquaculture.

Biological characteristics of marine Streptomyces SK3 and optimization of cultivation conditions for production of compounds against Vibiriosis pathogen isolated from cultured white shrimp (Litopenaeus vannamei).

Antibiotic resistance in shrimp farms has emerged as an extremely serious situation worldwide. The main aim of this study was to optimize the cultural conditions for producing new antibiotic agents from marine Streptomyces species. Streptomyces SK3 was isolated from marine sediment and was identified by its 16S rDNA as well as biochemical characteristics. This microbe produced the highest concentration of bioactive secondary metabolites (BSMs) when cultured in YM medium (YM/2). It produced the maximum total protein (41.8 ± 6.36 mg/ml) during the late lag phase period. The optimum incubation temperature was recorded at 30 °C; BSMs were not produced at ≤10 °C within an incubation period of 3-4 days. The suitable agitation speed was found to be 200 rpm with pH 7.00. The proper carbon, nitrogen, and trace elements supplementation consisted of starch, malt extract, calcium carbonate (CaCO3), and magnesium sulfate (MgSO4). The ethyl acetate extract was found to act strongly against three vibriosis pathogens, Vibrio harveyi, Vibrio parahaemolyticus, and Vibrio vunificus, as indicated by the inhibition zones at 34.5, 35.4, and 34.3 mm, respectively. The extract showed the strongest anti-V. harveyi activity, as indicated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 0.101 ± 0.02 and 0.610 ± 0.04 mg/ml, respectively. Basic chemical investigation of the crude extract using thin layer chromatography (TLC), bioautography, liquid chromatography tandem mass spectrometry (LC‒MS/MS), Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (1H-NMR) revealed that the active components were the terpenoid and steroid groups of compounds. They showed carboxylic acid and ester functions in their molecules.

The Effect of Probiotic Administration with Different Time Intervals on Water Quality in Shrimp Cultivation Vaname (Litopenaeus vannamei) Biofloc System

Vaname shrimp is one of the marine fishery commodities that has high economic value. Water in vaname shrimp cultivation must be maintained in quality. Ammonia can be harmful to shrimp, control of ammonia and organic matter content can be done biologically with the application of probiotics. Therefore, this study needs to be conducted to determine the right time interval in providing probiotics to the water quality of vaname shrimp cultivation in the biofloc system. The method used in this study is the experimental method, using RAL with 4 treatment levels and 3 repetitions, with treatment P0 (Once during maintenance), P1 (once every 5 days), P2 (once every 10 days) and P3 (once every 15 days), the probiotic used in this study is the probiotic Probio-7. The results of the study during 56 days of maintenance showed that the average value of water quality salinity 26.7-27 ppt, temperature 27.7-28°C DO 7.13-7.16 mg/L, nitrate 0.63-0.87 mg/L and Total Ammonia 0.76-0.92 mg/L. Based on the research activities that have been carried out, the interval of probiotic administration has a significant effect on water quality. Probiotic administration can increase the Total Ammonia content and reduce the amount of ammonia in this study. Probiotic administration with an interval of 5 days once (P1) gave a total ammonia value of 0.78 mg/L with an ammonia amount of 0.067 mg/L. P1 also gave the highest growth, absolute weight 5.61 g, absolute length 8.82 cm, SGR 5.779%/Day and FCR 1.47.

Authentication of Pacific white shrimp (Litopenaeus vannamei) reared in freshwater and seawater areas using fatty acid profiles combined with chemometrics

Fatty acid (FA) profiling in muscle and hepatopancreas of Litopenaeus vannamei was combined with k-nearest neighbor (KNN), and random forest (RF) to differentiate L. vannamei raised in freshwater and seawater areas. The FA profiles of the two tissues differed between L. vannamei cultured in freshwater and seawater. Moreover, six (C22:6n3, C20:3n3, C17:0, C18:3n3, C20:5n3, and C20:2) and seven (C22:6n3, C16:0, C18:3n3, C18:2n6, C20:2, C20:1, and C18:1n9) variables in muscle and hepatopancreas, respectively, were selected by orthogonal partial least squares-discriminant analysis (OPLS-DA) to create models for distinguishing L. vannamei cultured in freshwater and seawater. The most selected variables in muscle and hepatopancreas were related to salinity. Furthermore, using FA profiles from the two tissues, both KNN and RF had initial and cross-validated classification rates >93%, while the predictive classification rates of the models based on muscle FA profiles were higher than that of the models based on hepatopancreas FA profiles. Therefore, FA profiles in muscle were more effective than hepatopancreas FAs for identifying shrimps. FA profiling in muscle tissue represents a promising method for discriminating between L. vannamei cultured in freshwater and seawater.

A Review and Meta-Analysis of Genotype by Environment Interaction in Commercial Shrimp Breeding.

(1) Background: Genotype-by-environment interaction (G×E) can adversely impact genetic improvement programs. The presence of G×E is mainly measured as the genetic correlation between the same trait measured in different environments where departure from unity can be taken as presence of G×E. (2) Methods: To understand the extent of G×E in shrimp production, a review and meta-analysis was conducted using the results from 32 peer-reviewed studies. (3) Results: Of these, 22 G×E studies were conducted on Pacific white shrimp (Litopenaeus vannamei) with fewer studies reported in other shrimp species. The most frequently studied traits were growth and survival, with relatively few studies on traits of economic importance. The meta-analysis demonstrated a moderately high genetic correlation (rg = 0.72 ± 0.05) for growth, indicating low to moderate levels of G×E with some re-ranking of breeding values across environments. However, substantial G×E was evident for survival where only a moderate genetic correlation (rg = 0.58 ± 0.07) was observed for survival across different environments. A re-ranking of breeding values is likely for this trait and genetic improvement of shrimp for survival in one environment may not be effective in other environments. The results from ANOVA-based studies show that G×E accounted for 6.42 ± 1.05% and 7.13 ± 3.46% of the variation for growth and survival traits, respectively. (4) Conclusion: The significance of G×E necessitates tailored genetic improvement programs in commercial shrimp breeding. We discuss the scope and challenges of G×E for shrimp breeding programs, including opportunities of implementing G×E in genomic selection programs.

Development of DNA Markers for Acute Hepatopancreatic Necrosis Disease Tolerance in Litopenaeus vannamei through a Genome-Wide Association Study.

Shrimp aquaculture is facing a serious disease, acute hepatopancreatic necrosis disease (AHPND), caused by Vibrio paraheamolyticus (VpAPHND). For sustainable shrimp aquaculture, massive losses of shrimp infected with VpAPHND must be prevented. Research and selection of shrimp tolerant to VpAPHND infection is a sustainable approach to reducing the risk of AHPND. This study focused on the identification and development of potential DNA markers associated with AHPND using DArT sequencing (DArTSeq) and a genome-wide association study. Three populations of post-larval Litopenaeus vannamei were immersed in VpAPHND to collect susceptible (D) and tolerant (S) samples. The 45 D and 48 S shrimp had their genotypes analyzed using DArTSeq. A total of 108,983 SNPs and 17,212 InDels were obtained from the DArTseq data, while the biallelic 516 SNPs and 2293 InDels were finally filtered with PIC < 0.1, MAF < 0.05, and a call rate ≥ 80%. The filtered variants were analyzed for their association with AHPND tolerance. Although there were no significantly associated SNPs and InDels above the Bonferroni correction threshold, candidate variants, four SNPs and 17 InDels corresponding to p < 0.01, were provided for further validation of the AHPND tolerance trait. The candidate SNPs are located on an exon of the zinc finger protein 239-like gene, an intron of an uncharacterized gene, and in intergenic regions. Most of the candidate InDels are in the intergenic regions, with fewer in the intronic and exonic regions. This study provides information on SNPs and InDels for white shrimp. These markers will support the variant database of shrimp and be useful in shrimp aquaculture for breeding selection.

Nematodes Can Substitute Artemia in a Co-Feeding Regime for Pacific White Shrimp Post-Larvae Reared in a Biofloc Nursery System.

This study evaluated nematodes as an alternative to live Artemia when provided in a co-feeding regime to Pacific white shrimp (Penaeus vannamei) post-larvae (PL) reared in a biofloc nursery system. A 20-day experiment employing PL11 was performed for an evaluation of four dietary groups: control [C] (fed exclusively with a dry commercial feed); artificial Artemia [AA] (dry feed composed of extracted and processed Artemia cysts and dry commercial feed); live Artemia and dry commercial feed [LA]; and nematodes and dry commercial feed [N] (Panagrolaimus sp. dry nematodes). The diets were provided twice a day, with the remaining six feed provisions being a commercial dry feed for all experimental groups. A biofloc system was chosen as it offers a potentially sustainable approach to intensive shrimp farming. Alkalinity and pH in the [N] group were significantly higher in the last 5 days of the experiment (p < 0.05), likely causing the significantly lower nitrite levels observed in that same group (p < 0.05). Total and volatile suspended solids were significantly lower in the two live feed groups when compared with [C] and [AA] (p < 0.05). Although PL fed the dry diets exhibited higher growth rates (p < 0.05), the [N] and [LA] groups presented significantly higher final survivals (p < 0.05). No differences were found for survival after a salinity stress test (p ≥ 0.05). These results suggest that nematodes can successfully substitute Artemia in a co-feeding regime for P. vannamei PL reared in biofloc nursery systems.

Pilot-scale investigation of an advanced biofloc technology for treating Pacific white shrimp effluent: Performance and insight mechanisms

Biofloc technology (BFT) is extensively used in the treatment of water quality in intensive shrimp aquaculture systems. However, the rapid accumulation of biofloc in middle-to-late culture stages poses challenges for system management, impacting the economic yield of aquaculture operations. To address this issue, an advanced biofloc system (A-BS) that integrates a moving bed biofilm reactor (MBBR) with BFT was constructed, and the biofloc system (BS) was used as a control group. During a 100-day pilot-scale operation, the A-BS group effectively regulated water quality and enhanced the growth rate of Pacific white shrimp (Litopenaeus vannamei). In the A-BS group, the average concentrations of ammonia, nitrite, chemical oxygen demand, and mixed liquor suspended solids were substantially reduced compared to those in the BS group, measuring 0.19, 0.55, 36.36, and 229 mg/L, respectively, across the middle-to-late culture stages. Notably, the final stocking density and survival rate of shrimp in the A-BS group, reached 7.04 kg/m3 and 81.22 %, surpassing those in the BFT group. Furthermore, microbial community and functional gene analyses revealed more in-depth insights into the related mechanisms. Bacterial abundance and diversity, as well as the presence of denitrification genes such as Unclassified_f_Rhodobacteraceae and Paracoccus, were markedly higher in the A-BS group than in the BS group. The integration of MBBR into A-BS significantly increased the abundance of amoA and nirK genes, which are crucial for water quality stability during later culture stages. This proof-of-concept investigation confirms that the MBBR–BFT coupling process in A-BS holds promise for advancing sustainable aquaculture practice and provides strategic guidance for the modernization of the industry.

Immunofluorescence detection of Ecytonucleospora hepatopenaei (EHP) in Penaeus vannamei

Hepatopancreatic microsporidiosis (HPM), caused by the microsporidium Ecytonucleospora hepatopenaei (EHP) leads to retarded growth and enhanced susceptibility to other diseases in shrimp resulting in a major loss for the shrimp industry worldwide. It is little understood how EHP infects its host and hijacks its cellular machinery to replicate and exert clinical manifestations in infected shrimp. Since the initial record of HPM, histopathology and polymerase chain reaction (PCR)-based assays were developed for the detection of EHP to prevent spread of the disease. Availability of an antibody-based detection method would complement these existing diagnostic tools and be useful in studying EHP pathogenesis. We describe here an immunofluorescence assay (IFA) for detecting EHP using monoclonal antibodies (mAbs) that were originally developed against Cryptosporidium parvum, a coccidian parasite that infects calves (Bos taurus), other agriculturally important animals, and humans. Forty-one mAbs were screened and two mAbs, 3E2 and 3A12, were found to detect EHP successfully. The utility of these mAbs in detecting EHP was further assessed by testing 36 experimentally challenged EHP-infected shrimp (Penaeus vannamei). EHP-detection data from infected shrimp were compared by Hematoxylin and Eosin (H&E) histology, real-time PCR, and immunofluorescence. The data show IFA using mAbs 3E2 and 3A12 could successfully detect EHP and that the sensitivity of detection is comparable to H&E histology and quantitative PCR. Availability of mAbs that can detect EHP is expected to be immensely beneficial in HPM diagnosis. Since the pathobiology of C. parvum has been so widely studied, these cross-reactive mAbs may also aid in gaining some insight into EHP pathogenesis and disease.

Effects of dietary cholesterol on ovary development and reproductive capacity in Pacific white shrimp broodstock, Litopenaeus vannamei

Cholesterol is an important component of fresh biological baits and essential precursor to synthesize steroid hormones for crustacean. However, the cholesterol demand in Pacific white shrimp broodstock and its roles on ovary development and reproductive capacity are unknown. In the present study, female Pacific white shrimp broodstock (initial weight 51.3 ± 0.5 g) were fed with three diets contained 0.5 %, 1 % or 1.5 % cholesterol for 45 days. The results found that dietary cholesterol levels did not affect survival rate, weight gain, egg-laying number, vitellogenin content and vitellogenin receptor gene expression in the hepatopancreas. However, the hepatosomatic index, gonadosomatic index, egg diameter, vitellogenin level in the ovary and fertilized egg, C22:6n-3 (DHA) level in the fertilized egg, total protein, triglyceride and cholesterol contents were all increased in the 1.0 % and 1.5 % cholesterol groups than those in the 0.5 % cholesterol group. Moreover, compared with the 0.5 % and 1.0 % cholesterol groups, the 1.5 % cholesterol group had significantly higher gonad maturation number, mating rate, estradiol level in the hemolymph, steroid hormones synthesis related genes (HMGCR, StAR, 17βHSD and 1vMFBP) expression in the ovary and hepatopancreas. In conclusion, dietary 1.5 % cholesterol could promote ovary development and reproductive capacity in female Litopenaeus vannamei broodstock by improving nutrients accumulation and steroid hormones synthesis pathway. Our results provide guidance for design of artificial compound feed and healthy development of shrimp broodstock farm.

Influence of stocking density and interaction variability on disease progression of white spot syndrome virus-infected shrimp under different risk scenarios

White spot syndrome virus (WSSV), the causative agent of white spot disease (WSD), is the most significant viral pathogen affecting farmed shrimp. As the culture model for whiteleg shrimp has evolved into a higher-intensity model, the need to study the influence of stocking density on disease progression in pond culture systems has been reinforced. Therefore, we assessed WSD progression by deriving a direct correlation between seasonal disease outbreak risk, stocking density, and viral shedding rate (WSSV genome copies/L/g) using three different stocking densities: high (210 shrimp/m2), medium (140 shrimp/m2), and low (70 shrimp/m2). In Experiment 1 (three stocking densities at 25 °C) and Experiment 2 (stocking density × temperature conditions), shrimp showed relatively high cumulative mortality within the temperature range of optimal WSSV replication (23–29 °C). Notably, the mortality trend, peak viral loads, and viral shedding of WSSV-infected shrimp occurred earlier under high-density conditions, regardless of temperature. Thereafter, this study established WSD risk scenarios based on water temperature conditions and confirmed a significant difference in mortality trends between vulnerable and less vulnerable water temperature scenarios under high- and low-density conditions. The vulnerable water temperature scenario included constant (25 °C), shifting-up (20 °C to 30 °C), and shifting-down (30 °C to 20 °C) conditions, whereas the less vulnerable water temperature scenario included constant 20 °C and 30 °C conditions. Based on mortality trends, the WSD risk scenarios revealed that the times to 50 % mortality for shrimp at high, medium, and low densities were 4, 5, and 6 days post-infection (dpi) in the vulnerable water temperature scenario, and 6, 7, and 9 dpi in the less vulnerable water temperature scenario. Viral shedding variability was evaluated based on the correlation between viral loads and viral shedding rate, and linear regression analysis revealed a significant positive correlation between viral shedding rates and viral loads in shrimp, regardless of WSD risk scenarios or stocking density conditions. Notably, a relatively enhanced viral shedding rate was observed at higher stocking densities (from low- to high-density conditions) and under vulnerable water temperature scenarios. This study suggests that increased stocking density and vulnerable water temperature scenarios could induce greater interactions among WSSV-infected shrimp. It also confirmed the potential role of risk scenarios, stocking density, and viral shedding in WSD progression, providing insights into the disease outbreak mechanisms on shrimp farms.

Deformities in Litopenaeus vannamei caused by infectious hypodermal and hematopoietic necrosis viral (IHHNV) infection in intensive grow-out ponds of South east coast of India

Deformities in <i>Litopenaeus vannamei</i> caused by infectious hypodermal and hematopoietic necrosis viral (IHHNV) infection in intensive grow-out ponds of South east coast of India

Water Quality Assessment and its Impact on Shrimp in the Rupnarayan River: A Comparative Study from February to May of 2022-2024

The Rupnarayan River is the heart of the Purba Medinipur district of West Bengal, as it is the habitat of a large number of aquatic species and the main drinking, agricultural, irrigation, and cultivation resource. We collected river water samples from the Kolaghat, Alinan, Siuri and Deemari villages near Tamluk in the Purba Medinipur district. Then, we assessed different water quality parameters, such as temperature, turbidity, pH, DO, BOD, salinity, alkalinity, and hardness. We studied the premonsoon phase (Feb-May) and assessed the impact of these parameters on the production of shrimp species. We identified M. rosenbergi, M. brevicornis, M. monoceros, and Penaeus vannamei as shrimp species. We also compared the data from 2022 to 2024 (Feb-May) and observed yields of 40%, 60%, and 30% in 2022, 2023 and 2024, respectively.