Shrimp Farming Areas Research Articles

Impacts of culture-wise shrimp farming activities on hydrogeochemistry: a case study from Chidambaram taluk, Cuddalore district, Tamil Nadu, India

Shrimp farming is one of the most important aquaculture practices in terms of area, production, employment and foreign exchange generation in India. In recent years, the growth and intensification of shrimp farms in the study area have been explosive, and setting up of new shrimp farms along the coastal areas has also become a matter of apprehension among the environmentalists. An extensive survey made by environmentalists elsewhere shows mixed opinion, but ascertains the real scenario as facts. A total of about 46 groundwater samples were collected in five phases: pre-culture, summer culture, immediately after summer harvest (IASH), winter culture and immediately after winter culture, respectively. The results revealed that the high value of TDS, Na, Cl and Br is observed in IASH, and also, the spatial distribution map confirmed that higher concentration is observed near to the creek and sea. Moreover, the abundance of these ions is in the following order: Na > Ca > Mg > k and Cl > HCO3 > SO4 > CO3 > NO3 > Br for different culture periods, respectively. Piper diagram depicts that the groundwater was controlled by ion exchange reactions. Further, Chadha’s classification revealed that the reverse ion exchange was the dominated feature, and it is supported by various ionic indices such as Na/Cl versus EC, (Ca + Mg) versus (SO4 + HCO3), (Na–Cl) versus (Ca + Mg–HCO3–SO4), (Ca + Mg) versus Cl and Na/Cl versus Cl, respectively. The result of factor analysis shows that most of the variations are elucidated by the seawater intrusion, rock–water interactions and anthropogenic activities during different culture periods. The spatial distribution map of factor scores clearly delineates that the positive values are observed near to the creek and sea and in that, shrimp farming area is not predominated. R-mode cluster analysis shows that groundwater quality does not vary extensively as a function of culture periods. Moreover, Q-mode classification consists of two clusters: the first cluster has a high saline water concentration comprising samples location near to the creek and sea. The second cluster mainly depends upon rock–water interactions and the majority of shrimp farming area are grouped under these categories. The above statements clearly indicate that groundwater parameters mainly depend upon the geological process and that shrimp farming cannot be targeted as the root cause for groundwater salinization.

Dynamics of Shrimp Farming in the Southwestern Coastal Districts of Bangladesh Using a Shrimp Yield Dataset (SYD) and Landsat Satellite Archives

The shrimp-farming area and shrimp yield are continuously changing in the southwestern coastal districts of Bangladesh. The three southwestern coastal districts, Bagerhat, Satkhira, and Khulna, along with Rampal, a subdistrict of Bagerhat, contribute 75% of the total shrimp yield of Bangladesh. However, the shrimp yield and farming area have declined in Bagerhat district, and the cause of this decline is uncertain. In this research, the differences in the shrimp yield were quantified using a shrimp yield dataset (SYD) and k-means classification. A supervised image classification approach was applied to quantify the spatiotemporal changes and identify the influencing factors behind the declining shrimp-farming area and yield in Rampal, Bagerhat district, using Landsat satellite archives. K-means classification reveals that, between 2015 and 2017, the shrimp yield in Bagerhat district declined significantly compared to Satkhira and Khulna. The satellite-based monitoring results affirm that the shrimp-farming area of Rampal also decreased rapidly, from 21.82% in 2013 to 6.52% in 2018. This research estimates that approximately 70% of the shrimp-farming area was lost in Rampal since December 2013. Hence, the findings of this research might motivate the responsible bodies to declare the shrimp-farming coastal area as a “shrimp zone” and implement an active policy to protect the vulnerable shrimp-farming industry and shrimp farmers, considering it is the second-largest export earning source in Bangladesh after ready-made garments.

Shrimp vs prawn-rice farming in Bangladesh: A comparative impacts study on local environments and livelihoods

Both the freshwater prawn and saline water shrimp in Bangladesh locally known as white gold because of their high transactional value. Though coastal agro-climatic conditions are suitable for both shrimp and prawn, availability of resources in addition to easy and cheap operational manner triggers the rapid expansion of shrimp farming compare to prawn farming in southwest coastal part of Bangladesh. But unplanned expansion of shrimp farming has raised several concerns regarding environmental and social aspects. Average soil salinity has been increased more than 6 times and in some areas 10 to 15 times from 1984 to 2014. The present study aims to expound the impact of shrimp and prawn-rice farming on agriculture, livestock and livelihoods of local marginal farmers who are the majority of the society. The results showed salinity intrusion due to shrimp farming significantly reduced crops and livestock production, and ceased many livelihood options in the shrimp farming areas; but in same time period prawn-rice farming system creates versatile employment opportunities including significant growth of agricultural crops production. The household income of marginal farmers was found almost double in prawn farming areas (BDT 13,880) than that of shrimp farming areas (BDT 7718). Higher production cost of prawn-rice farming (BDT 307,816 ha−1 year−1) than shrimp farming (BDT 94,811 ha−1 year−1) often compel the farmers to adopt shrimp farming despite the higher net return from prawn-rice farming (BDT 192,520 ha−1 year−1) to shrimp farming (BDT 122,629 ha−1 year−1) as well. Overall findings of the study indicate a huge prospect of promoting prawn-rice farming through adequate institutional arrangement, which will protect the socio-economy of the marginal locals and sustainability of the local environment simultaneously.

ANTIBIOTICS AND PESTICIDES IN WATER AND SEDIMENTS FROM INTENSIVE SHRIMP FARMS IN SOUTHERN VIETNAM

In recent years, shrimp farming has developed rapidly and become one of the major export sectors of Vietnam. In particular, Mekong Delta Vietnam (MDVN) accounts for over 90 % shrimp farming area in Vietnam. Shrimp industry development leads to use a large amount of antibiotics (ABs) and pesticides for disease prevention, treatment and sanitation pond. These compounds are usually discharged directly into the environment through water and sludge after harvesting. The presence of antibiotics and pesticides in the environment cause negative impacts on ecosystems and human health. In this study, the passive sampling method with POCIS sampler (Polar Organic Chemical Integrative Samplers) was used to monitor the presence of 12 ABs and 2 pesticides in water of intensive shrimp ponds and the surrounding canals at Tan Tru District (Long An province) and Can Gio District (Ho Chi Minh city) following a production cycle. The results showed that ABs and pesticides were detected in water and sediment in the pond and canals in both research sites. Two pesticides (atrazine and diuron) were detected in the pond and leading canals in both study areas with low concentrations from several ng/L to several tens of ng/L. In Tan Tru, three antibiotics (Trimethoprim, Sulfamethoxazole and Enrofloxacin) were detected in water at concentrations ranging from several tens of ng/L to 300 ng/L; in sediments of shrimp pond and canal the levels of pesticides and ABs ranged from 10 to 200 µg/kg. In Can Gio - HCMC, 4 ABs (Trimethoprim, Sulfamethoxazole, Ciprofloxacin and Enrofloxacin) were detected ranging from a few ng/L to several µg/L in water, and a few mg/kg in sediments of the pond. The results also showed that in the pond, ABs type and concentration detection varied by region and shrimp growth cycles.

Analysis of antibiotic multi-resistant bacteria and resistance genes in the effluent of an intensive shrimp farm (Long An, Vietnam)

In Vietnam, intensive shrimp farms heavily rely on a wide variety of antibiotics (ABs) to treat animals or prevent disease outbreak. Potential for the emergence of multi-resistant bacteria is high, with the concomitant contamination of adjacent natural aquatic habitats used for irrigation and drinking water, impairing in turn human health system. In the present study, quantification of AB multi-resistant bacteria was carried out in water and sediment samples from effluent channels connecting a shrimp farming area to the Vam Co River (Long An Province, Vietnam). Bacterial strains, e.g. Klebsiella pneumoniae and Aeromonas hydrophila, showing multi-resistance traits were isolated. Molecular biology analysis showed that these strains possessed from four to seven different AB resistance genes (ARGs) (e.g. sul1, sul2, qnrA, ermB, tetA, aac(6)lb, dfrA1, dfr12, dfrA5), conferring multidrug resistance capacity. Sequencing of plasmids present within these multi-resistant strains led to the identification of a total of forty-one resistance genes, targeting nine AB groups. qPCR analysis on the sul2 gene revealed the presence of high copy numbers in the effluent channel connecting to the Vam Co River. The results of the present study clearly indicated that multi-resistant bacteria present in intensive shrimp cultures may disseminate in the natural environment. This study offered a first insight in the impact of plasmid-born ARGs and the related pathogenic bacteria that could emerged due to inappropriate antibiotic utilization in South Vietnam.

Land-Use/Land-Cover Change Dynamics and Groundwater Quality in and around Shrimp Farming Area in Coastal Watershed, Cuddalore District, Tamil Nadu, India

The present study was envisaged mainly to ascertain the influence of aquaculture on salinization of coastal groundwater resources in the Cuddalore district of Tamil Nadu located between 11°30'N–11°20'N and 79°38'E–79°48'E. Watershed-based multidisciplinary approach combining GIS and Remote Sensing, and hydro-geochemistry has been applied. The land-use study revealed that though aquaculture was initiated after 1991, the groundwater quality in some locations showed elevated total dissolved solids and electrical conductivity content during that time itself, supporting the fact that aquaculture has been initiated in in situ saline area. Land-use change dynamics showed no defined relationship between area of culture and the groundwater quality, indicating that there was no salinity build-up due to shrimp farming. Besides major chemical compositions, the hydro-geochemical analysis using Chadha’s plot suggests that reverse ion exchange is dominant in the study area due to the natural geological condition and it controls the groundwater quality rather than sea water incursion to a large extent. Thus these analyses clearly bring out the fact that shrimp farming is not the main reason for the source of salinity in the study area.

Microbiome Dynamics in a Shrimp Grow-out Pond with Possible Outbreak of Acute Hepatopancreatic Necrosis Disease

Acute hepatopancreatic necrosis disease (AHPND) (formerly, early mortality syndrome) is a high-mortality-rate shrimp disease prevalent in shrimp farming areas. Although AHPND is known to be caused by pathogenic Vibrio parahaemolyticus hosting the plasmid-related PirABvp toxin gene, the effects of disturbances in microbiome have not yet been studied. We took 62 samples from a grow-out pond during an AHPND developing period from Days 23 to 37 after stocking white postlarvae shrimp and sequenced the 16S rRNA genes with Illumina sequencing technology. The microbiomes of pond seawater and shrimp stomachs underwent varied dynamic succession during the period. Despite copies of PirABvp, principal co-ordinates analysis revealed two distinctive stages of change in stomach microbiomes associated with AHPND. AHPND markedly changed the bacterial diversity in the stomachs; it decreased the Shannon index by 53.6% within approximately 7 days, shifted the microbiome with Vibrio and Candidatus Bacilloplasma as predominant populations, and altered the species-to-species connectivity and complexity of the interaction network. The AHPND-causing Vibrio species were predicted to develop a co-occurrence pattern with several resident and transit members within Candidatus Bacilloplasma and Cyanobacteria. This study’s insights into microbiome dynamics during AHPND infection can be valuable for minimising this disease in shrimp farming ponds.

Key factors affecting the flood vulnerability and adaptation of the shrimp farming sector in Thailand

Increasing climate variability, particularly flooding, severely impacts shrimp production yields and global seafood supply. Effective reduction of the impacts of flood vulnerability depends on level and readiness of the adaptive capacity. This study investigated key factors affecting the adaptive capacity of shrimp farmers in Thailand. This case study focused on the largest shrimp farming areas at a provincial level. Data collection was carried out using questionnaires and person-to-person interviews. Approximately 100 shrimp farmers who had experienced previous flood events were interviewed to help classify the impact scales of key factors on adaptation. Five socio-economic characteristics (education level, farming experience, income level, farm size, and supplemental occupations) are important factors in making the decision to apply adaptive alternatives. Currently, the main adaptive practices employed by shrimp farmers in the study area are placing nets around ponds and constructing dykes to enclose shrimp ponds. However, poverty and limited access to financial resources are the major constraints affecting the adaptive capacity to combat future flooding events. For farmers whose farms are located in vulnerable areas and who have limited financial resource, an implementation of non-structural techniques, such as changing crop patterns and altering harvest seasons, should be promoted.

Assessment of groundwater vulnerability mapping using AHP method in coastal watershed of shrimp farming area

Groundwater regions in coastal aquifers are highly vulnerable with increase in urbanization, industrialization and sea water intrusion. The present study attempts to evaluate the vulnerability of groundwater in a coastal watershed of shrimp farming areas. The study area is categorized in the GIS-based AHP environment into three ranges (high, medium, and low vulnerability) using various groundwater parameters such as electrical conductivity (EC), total dissolved solids (TDS), sodium percentage (Na%), total hardness (TH), revelle coefficient, sodium adsorption ratio (SAR), permeability index (PI), and residual sodium carbonate (RSC) and their recommended limits. GIS-based AHP weighted index overlay analysis technique has been proven to be a powerful tool to evaluate the distribution of groundwater vulnerability in the study area. The high vulnerable areas were noted in downstream with a strong contamination of the seawater intrusion along the coastal zone and in proximity of the river. Multivariate statistical techniques are also applied to identify and assess the groundwater vulnerability of the study area. The factor analysis revealed that groundwater quality is strongly affected by rock–water interaction, saline water intrusion, and anthropogenic activities. The spatial distribution map of factor-scores showed the gradual variation in groundwater geochemistry from the western part (upstream) to the eastern part (downstream) of the river. The results from the present study revealed that shrimp farming areas have very least or no impact on the groundwater of the region.

Habitat utilization by wetland birds of Munderikadavu, a proposed bird sanctuary in northern Kerala, India

Munderikadavu is rich in avifaunal diversity. A total of 82 species of birds from 36 families belonging to 13 orders were recorded in the wetland including wetland dependant species. Lowland vegetation had the highest species richness (46 species) followed by upland (41 species), aerial (38 species), emergent vegetation (22 species) and paddy fields (21 species). Open water had the lowest species richness. Upland vegetation had the highest species diversity (H′-3.19) followed by aerial (H′-2.52). There was more species overlap between emergent and low land vegetations (Cm-0.7). The threats in Munderikadavu wetland were dumping of waste and conversion of cultivation land into shrimp farming area. Thus land use changes need to be regulated in order to conserve the wetland and bird community.

Trend analysis of weather data in shrimp farming areas of Nagapattinam district of Tamil Nadu

Examining the trends and building the forecasting models for the meteorological parameters has got significance in climate research. An attempt was made to study the trends of temperature and rainfall of Nagapattinam District, a main shrimp farming area in Tamil Nadu. Surface weather data of the study area obtained from Indian Meteorological Department, Pune were analysed using Mann–Kendall trend test (MK test) for the weather parameters viz., maximum, minimum, highest maximum (HMax), lowest minimum (LMin) and mean temperatures, rainfall and number of rainy days. Month-wise, seasonwise (winter, summer and rainy) and year-wise trends were computed for the monthly data from 1961 to 2000. Results of analysis revealed a significant trend for maximum temperature for all the cases of experimentation, whereas the trend was significant for few months or seasons for minimum, mean, highest and lowest temperatures and number of rainy days. Trend does not exist for rainfall of the region. Time series forecasting model was built for monthly maximum temperatures using the data from 1961 to 1980 for building the model and evaluated with the data from 1981 to 2000. Autoregressive integrated moving average model (ARIMA) (2, 0, 1) (1, 1, 1) s was found to be suitable model with highest R2 value of 0.94 and lowest Root Mean Square Error. Model predictions were reassessed with Willmott’s index and found to be reasonably good (0.95) for the study area. The forecasting model for temperature in the study area can be used for shrimp farming crop calendar planning.

Social and ecological challenges of market-oriented shrimp farming in Vietnam

Vietnam is one of the largest shrimp exporters in the world. Since 2010, Vietnam has earned about two billion dollars annually through shrimp exports. As a fertile area of greatest potential for agricultural production in Vietnam, the Mekong Delta has been a major contributor to the country’s achievements, especially in the agricultural sector. During recent decades, trade liberation along with various policies in support of aquaculture has accelerated the development of shrimp production in the Delta. Based on an ethnographic study of shrimp farming in the Mekong Delta of Vietnam, I assert that along with great rewards arising from the expansion of shrimp farming areas, productivity, and export value, the shrimp industry has brought various environmental, economic and social challenges. Consequently, shrimp farming is a risky business and local inhabitants have relied on various strategies to cope with these challenges. Risk mitigation in shrimp production and labor migration are the two important strategies of local inhabitants for securing their livelihoods. Water pollution and poor quality post-larvae shrimp are direct consequences of market-oriented production.

Land cover and land use change related to shrimp farming in coastal areas of Quang Ninh, Vietnam using remotely sensed data

Rapid development of shrimp farming may lead to unrecognized and undesirable changes of land cover/land use patterns in coastal areas. Of special concern is the loss of mangrove forest in coastal areas such as Quang Ninh, Vietnam, which is adjacent to the World Heritage-listed Ha Long Bay. Understanding the status and changes of land cover/land use for coastal shrimp farms and mangrove forests can support environmental protection and decision-making for sustainable development in coastal areas. Within this context, this paper uses the 1999/2001 Landsat ETM+ and the 2008 ALOS AVNIR-2 imagery to investigate the contraction and expansion of shrimp farms and mangrove forests in coastal areas of Ha Long and Mong Cai, which now have a high concentration of intensive and semi-intensive shrimp farms. Images were separately analyzed and classified before using post-classification comparisons to detect land cover/land use changes in the study area. The results of this study found that the area of mangrove forest has been reduced by an estimated 927.5 ha in Ha Long and 1,144.4 ha in Mong Cai, while shrimp farming areas increased by an estimated 1,195.9 and 1,702.5 ha, respectively, over the same period. The majority of shrimp farms in Mong Cai were established at the expense of mangrove forest (49.4 %) while shrimp farms in Ha Long were mainly constructed on areas previously occupied by bare ground (46.5 %) and a significant proportion also replaced mangroves (23.9 %). The remarkable rate of mangrove loss and shrimp farming expansion detected in this study, over a relatively short time scale indicate that greater awareness of environmental impacts of shrimp farm expansion is required if this industry is to be sustainable, the important estuarine and coastal marine ecosystems are to be protected over the long term, and the capturing and storing of carbon in mangrove systems are to be enhanced for global climate change mitigation and for use as carbon offsets.

Sequencing and De Novo Analysis of the Hemocytes Transcriptome in Litopenaeus vannamei Response to White Spot Syndrome Virus Infection

BackgroundWhite spot syndrome virus (WSSV) is a causative pathogen found in most shrimp farming areas of the world and causes large economic losses to the shrimp aquaculture. The mechanism underlying the molecular pathogenesis of the highly virulent WSSV remains unknown. To better understand the virus-host interactions at the molecular level, the transcriptome profiles in hemocytes of unchallenged and WSSV-challenged shrimp (Litopenaeus vannamei) were compared using a short-read deep sequencing method (Illumina).ResultsRNA-seq analysis generated more than 25.81 million clean pair end (PE) reads, which were assembled into 52,073 unigenes (mean size = 520 bp). Based on sequence similarity searches, 23,568 (45.3%) genes were identified, among which 6,562 and 7,822 unigenes were assigned to gene ontology (GO) categories and clusters of orthologous groups (COG), respectively. Searches in the Kyoto Encyclopedia of Genes and Genomes Pathway database (KEGG) mapped 14,941 (63.4%) unigenes to 240 KEGG pathways. Among all the annotated unigenes, 1,179 were associated with immune-related genes. Digital gene expression (DGE) analysis revealed that the host transcriptome profile was slightly changed in the early infection (5 hours post injection) of the virus, while large transcriptional differences were identified in the late infection (48 hpi) of WSSV. The differentially expressed genes mainly involved in pattern recognition genes and some immune response factors. The results indicated that antiviral immune mechanisms were probably involved in the recognition of pathogen-associated molecular patterns.ConclusionsThis study provided a global survey of host gene activities against virus infection in a non-model organism, pacific white shrimp. Results can contribute to the in-depth study of candidate genes in white shrimp, and help to improve the current understanding of host-pathogen interactions.

Assessment and monitoring of nutrient loading in the sediments of tidal creeks receiving shrimp farm effluent in Quang Ninh, Vietnam

Coastal shrimp farming may lead to the contamination of sediments of surrounding estuarine and marine ecosystems as shrimp farm effluent often contains high levels of pollutants including a range of organic compounds (from uneaten feed, shrimp feces, and living and dead organisms) which can accumulate in the sediments of receiving waterways. The assessment and monitoring of sediment quality in tidal creeks receiving shrimp farm effluent can support environmental protection and decision making for sustainable development in coastal areas since sediment quality often shows essential information on long-term aquatic ecosystem health. Within this context, this paper investigates nutrient loadings in the sediments of tidal creeks receiving shrimp farm effluent in Quang Ninh, Vietnam, which now have a high concentration of intensive and semi-intensive shrimp farms. Sediment samples taken from inside creek sections directly receiving effluent from concentrated shrimp farms (IEC), from main creeks adjacent to points of effluent discharge outside concentrated shrimp farms (OEC), and few kilometers away from shrimp farms (ASF) as reference sites were collected and analyzed before and after shrimp crops to investigate spatial and temporal variation. The results showed that there were statistically significant differences in the concentrations of total nitrogen, total phosphorus, and total organic carbon among IEC, OEC, and ASF sites while the seasonal variation being limited over study times. A sediment nutrient index (SNI) computed from coefficient scores of the factor analysis efficiently summarizes sediment nutrient loads, which are high, albeit quite variable, in canals directly receiving effluents from farms but then decline sharply with distance from shrimp farms. The visualization and monitoring of sediment quality data including SNI on maps can strongly support managers to manage eutrophication at concentrated shrimp farming areas, contributing to sustainable development and management at coastal zones.

Assessment of hydrogeochemical characteristics of groundwater in shrimp farming areas in coastal Tamil Nadu, India

Brackishwater aquaculture is basically farming in coastal region, and it utilizes the saline water from either sea or estuary or creek. Assessment of hydrogeochemisty of groundwater resources in shrimp farming areas is very much required not only for monitoring the shrimp farming impacts, but also to suggest better management strategies for the long-term sustainability of shrimp farming and integrated water resources management in coastal regions. Watershed-based assessment is ideal as watershed is a geohydrological unit, and it will give the realistic and cumulative effects more precisely. With this background, the present investigation was carried out to evaluate the geochemical process regulating groundwater quality in shrimp farming areas of coastal miniwatersheds of Vellar and Coleroon river, Cuddalore district, Tamil Nadu, along the east coast of India. Representative groundwater (29) samples from shallow aquifer (hand pump and open well) were collected periodically (June 2008, January 2009, April 2009 and July 2009) using the simple random sampling method and analyzed for various water quality parameters viz. pH, TDS, total hardness, alkalinity, cations (Ca+, Mg+, Na+) and anions (Cl−, SO4 −, NO3 −, HCO3 −). The groundwater data indicated that the HCO3 was the dominant ion in the study area with sodium (Na > Ca > Mg) and bicarbonate (HCO3 > Cl > SO4) as the predominant cation and anion, respectively. The large variations in mean and standard deviation of ionic concentration suggest that the water chemistry in the study region was not homogenous and may be influenced by complex sources for the hydrogeochemical processes. The piper trilinear diagram depicts the status of the groundwater quality and also suggests that the cation exchange and mineral dissolution was responsible for this elevated ionic composition at some locations in the study area. The multivariate statistical analysis viz., principal component analysis and cluster analysis clearly elucidated that the groundwater quality in the area is mainly due to natural process and the shrimp farming is not an influencing factor.

Remote Sensing in Mapping Mangrove Ecosystems — An Object-Based Approach

Over the past few decades, clearing for shrimp farming has caused severe losses of mangroves in the Mekong Delta (MD) of Vietnam. Although the increasing importance of shrimp aquaculture in Vietnam has brought significant financial benefits to the local communities, the rapid and largely uncontrolled increase in aquacultural area has contributed to a considerable loss of mangrove forests and to environmental degradation. Although different approaches have been used for mangrove classification, no approach to date has addressed the challenges of the special conditions that can be found in the aquaculture-mangrove system in the Ca Mau province of the MD. This paper presents an object-based classification approach for estimating the percentage of mangroves in mixed mangrove-aquaculture farming systems to assist the government to monitor the extent of the shrimp farming area. The method comprises multi-resolution segmentation and classification of SPOT5 data using a decision tree approach as well as local knowledge from the region of interest. The results show accuracies higher than 75% for certain classes at the object level. Furthermore, we successfully detect areas with mixed aquaculture-mangrove land cover with high accuracies. Based on these results, mangrove development, especially within shrimp farming-mangrove systems, can be monitored. However, the mangrove forest cover fraction per object is affected by image segmentation and thus does not always correspond to the real farm boundaries. It remains a serious challenge, then, to accurately map mangrove forest cover within mixed systems.

Key Performance Characteristics of Organic Shrimp Aquaculture in Southwest Bangladesh

In Bangladesh, black tiger shrimp (Penaeus monodon; Fabricius, 1798) aquaculture has come to be one of the most important sectors in both the rural and national economies. Likewise, organic shrimp aquaculture has emerged as an alternative farming enterprise for farmers especially in the southwestern districts of Bangladesh. The present study aims to show key performance characteristics of organic shrimp farmers and farming in a prototypical shrimp farming area in Bangladesh. Data was collected in 2009 from organic shrimp farmers in the Kaligonj and Shyamnagar sub-districts through questionnaire interviews, transect walks and focus group discussions. The mean productivity of organic shrimp farming in the area is 320 kg ha−1 yr−1 (ranging from 120 to 711 kg ha−1year−1). Organic farmers are more likely to have a higher monthly income and less aquaculture experience. Moreover, suitable landholdings and classified labor distribution have been found to play an important role in the development of organic shrimp aquaculture. The most common assets of organic shrimp aquaculture are high yield, low production cost, available post larvae and high market prices. Small business farmers are likely to earn more income benefits from organic shrimp aquaculture than their larger-scale counterparts. Finally, the paper suggests that more research is needed to stimulate the success of organic shrimp aquaculture.

Feeding hermit crabs to shrimp broodstock increases their risk of WSSV infection

White spot syndrome virus (WSSV) is a serious shrimp pathogen that has spread globally to all major shrimp farming areas, causing enormous economic losses. Here we investigate the role of hermit crabs in transmitting WSSV to Penaeus monodon brooders used in hatcheries in Vietnam. WSSV-free brooders became PCR-positive for WSSV within 2 to 14 d, and the source of infection was traced to hermit crabs being used as live feed. Challenging hermit crabs with WSSV confirmed their susceptibility to infection, but they remained tolerant to disease even at virus loads equivalent to those causing acute disease in shrimp. As PCR screening also suggests that WSSV infection occurs commonly in hermit crab populations in both Vietnam and Taiwan, their use as live feed for shrimp brooders is not recommended.

Deep insight into white spot syndrome virus vaccines: A review

White spot syndrome virus (WSSV), the causative virus of the disease, is found in most shrimp farming areas of the world, where it causes large economic losses to the shrimp farming industry. The potentially fatal virus has been found to be a threat not only to all shrimp species, but also to other marine and freshwater crustaceans, such as crab and crayfish. To date, no effective prophylactic treatment measures are available for viral infections in shrimp and other crustaceans. Due to current aquaculture practices and the broad host range of WSSV, intervention strategies including vaccination against this virus would be pivotal to save and protect shrimp farming. Several achievements have been attained in the search of novel vaccines for WSSV. DNA vaccination, recombinant vaccines, oral vaccination techniques and gene therapy are some of the thrust areas of focus for scientists and researchers. This review article highlights the recent trends in the development of WSSV vaccines either as DNA vaccines or recombinant vaccines and their functioning strategies as suggested by the researchers worldwide.