Shrimp Producers Research Articles

Performance of an intensive nursery system for the Pacific white shrimp, Litopenaeus vannamei, under limited discharge condition

The considerable impact of disease outbreaks on commercial shrimp farming during the last two decades has significantly affected the operational management of shrimp farms worldwide. Crop losses forced shrimp producers to look for more sustainable culture practices and facility designs to minimize the risk associated with exposure to viral pathogens. Shrimp culture under limited discharge can increase biosecurity and minimize losses to disease outbreaks while reducing negative environmental impact. A 71-day nursery study was conducted in greenhouse-enclosed raceways to evaluate the effect of two water exchange regimes and the use of foam fractionators on selected water quality indicators, growth, survival, and health of Litopenaeus vannamei postlarvae (PL). Four 40m3 raceways were stocked with 4–5-day-old PL at a density of 4050PLm−3. All raceways were equipped with high pressure rapid sand filter, a pump, a center longitudinal partition over a 5.1cm PVC pipe with nozzles, eighteen 5.1cm airlift pumps, six 1m long air diffusers and a 5.1cm Venturi injector. Two out of the four raceways were each equipped with a home-made foam fractionator (FF). Average water usage in the two raceways operated with FF was 3.35%d−1 compared to the 9.37%d−1 used in the other two. Shrimp in the raceways operated with FF and the lower water exchange had greater mean final weight (1.91 and 2.0g vs. 1.73 and 1.43g), survival (100 and 92.4% vs. 55.9 and 81.8%), yield (7.64 and 6.89kgm−3 vs. 3.92 and 4.74kgm−3) and FCR (0.97 and 1.06 vs. 1.36 and 1.64) values than those operated without FF and with higher water exchange rate. Disease diagnostic results showed no signs of viral pathogen infection. Histological observations of samples collected at the study termination suggest that the shrimp raised in the higher water exchange raceways had greater external fouling and higher intestinal bacterial load than those maintained at lower water exchange. Nitrite–nitrogen was significantly lower in the reduced water exchange than the higher exchange raceways, whereas reactive phosphorus, turbidity, and algal density were significantly higher. No other differences in water quality were found between treatments. This study demonstrated the feasibility of producing healthy juveniles of the Pacific white shrimp under limited discharge conditions in tanks operated with foam fractionators with good growth, survival, yield and FCR results.

COMPARISON OF FREEZING AND THAWING TREATMENTS ON MUSCLE PROPERTIES OF WHITELEG SHRIMP (LITOPENAEUS VANNAMEI)

ABSTRACT Whiteleg shrimp (Litopenaeus vannamei) is traded as a frozen food. Changes in texture of thawed muscle are a negative economic factor. This study evaluated and compared two freezing methods, cryogenic and forced convection, and two thawing methods, at 4 and 25C by histological, textural and electrophoretical tests. Insignificant interaction was found between the two main effects for any of the evaluated texture parameters (shear force, fracturability, hardness and water-holding capacity). Significant differences (P < 0.05) were found in muscle protein sarcoplasmic fraction. Interaction of the main effects was only observed when analyzing microstructure. In all treatments, a significant increase in melanosis was detected when compared with unfrozen specimens. Because texture was not significantly affected by either freezing method, for commercial purposes, we suggest forced convection freezing because it is cheaper. For research concerning cell and tissue structure, cryogenic freezing is recommended. Thawing at 4C is recommended for marketing purposes. PRACTICAL APPLICATIONS Whiteleg shrimp as a food is considered in the world market as a high-value commodity. It is a suitable animal for farming, because it can grow under varied conditions. Making the shrimp culture an important worldwide economic activity that contributes positively to the economies of countries that commercialize shrimp. That is possible because all steps in farming are considered; however, in most examples, postharvesting management is neglected, tampering previous investments and efforts. The present study is suited in helping the shrimp industry. Knowledge about the effect of freezing–thawing on muscle properties such as texture may help shrimp producers and retailers select conditions of preservation to keep texture properties of the product pleasing to the consumer.

Shrimp farming in China: Operating characteristics, environmental impact and perspectives

China has been one of the world's largest shrimp producers since 1988. Although the industry suffered disease outbreaks and environmental problems, shrimp farming has recently seen a rapid expansion in China. This study provides some necessary background to shrimp aquaculture in China. It focuses briefly on the operating characteristics of shrimp aquaculture. Emphasis is placed on the shrimp farming impact on the environment. The promising strategy for reductions in nutrient release from shrimp aquaculture is analyzed. The effective management measures to resolve or mitigate the adverse environmental impact of shrimp farming development have now become necessary and urgent.

Efficiency and sensitivity determination of Shrimple®, an immunochromatographic assay for white spot syndrome virus (WSSV), using quantitative real-time PCR

White spot syndrome virus (WSSV) is a prevalent and virulent pathogen affecting both wild and cultured penaeid shrimp worldwide. Molecular diagnostic tools have made detection of the virus increasingly accurate. However, these techniques are often not readily available for rapid diagnosis in the field or in shrimp production facilities. Shrimple®, an immunochromatographic detection assay for WSSV, was designed specifically for use by shrimp producers. In this study, WSSV-infected shrimp were tested with both real-time PCR and Shrimple®, in order to determine the range of sensitivity in which the diagnostic test kit is capable of detecting viral infection and the efficiency of the test kit when compared to the real-time PCR. Litopenaeus vannamei were injected with a WSSV inoculum and sampled from 1 to 32 h post injection (p.i.), prior to developing gross anatomical signs of disease. By analyzing the corresponding samples from each specimen, the Shrimple® test results were correlated with estimated viral copy numbers from quantitative PCR. Real-time PCR detected infections in 100% of the inoculated shrimp, while the Shrimple® test kits detected infection in only 34.7% of the specimens. The findings of this study indicate that the Shrimple® test kits fail to detect WSSV infection prior to 12 h post infection and demonstrate a significant reduction in detection efficiency during early onset of infection—failing to detect any viral infection from 1 to 8 h p.i. compared to 100% with real-time PCR. False negative results were observed for specimens containing 4-1061 viral copies/ng genomic DNA. Faint positives were observed for specimens containing 36-1784 viral copies/ng genomic DNA. Although considerably less sensitive than real-time PCR, the Shrimple® test kits provide a useful tool for the detection of WSSV infections prior to development of gross signs of acute disease.

MEASURING PRODUCT DIFFERENCES BY SENSORY ANALYSIS: THE CASE OF IMPORTED AND U.S. DOMESTIC SHRIMP

The increased dominance of imported shrimp in the U.S. market has led to lower prices received by domestic shrimp producers. One way domestic shrimp producers might be able to receive higher prices is by marketing it as a premium product easily differentiated from imported individually quick-frozen (IQF) shrimp. Four panels covering two groups (consumers and chefs) and two cooking methods were asked to rate sensory attributes related to shrimp. Results show that consumer panels rate IQF shrimp higher than South Carolina fresh and frozen (SC fresh and frozen, respectively) shrimp across many sensory attributes. Results from the chef panels, although also indicating a number of advantages for IQF shrimp, reveal attributes where SC fresh and frozen shrimp have an edge. Flavor ratings are highly correlated with overall ratings for a particular shrimp, and this influenced a panel's shrimp preference. Future marketing efforts geared toward turning U.S. domestic shrimp into a premium product should concentrate on reintroducing domestic shrimp to U.S. consumers who have been used to imported IQF shrimp. Advantages of domestic frozen shrimp in terms of texture and appearance as noted by the chef panels should also be exploited.

Sustainable aquaculture and producer performance: measurement of environmentally adjusted productivity and efficiency of a sample of shrimp farms in Mexico

The competition among shrimp producing countries, the rapid advances in technology and the increase in market demand suggest that the shrimp industry at a global level and in Mexico in particular needs to take appropriate measures to maintain its viability and be able to compete successfully. This can be achieved by making better use of the available scarce resources and appropriate technology without further deteriorating the environment. Decision makers, i.e. policy-makers and farmers, are challenged with the responsibility of planning and conducting aquaculture development in a sustainable way whereby social, environmental and economic goals are simultaneously satisfied. Based on an unbalanced panel of semi-intensive shrimp farms containing primary-source information at pond level for the period 1994, 1996–1998 in northwest Mexico, this paper assesses farm performance indicators adjusted to incorporate environmental impacts. This 4-year time series coincides with a switch in the species reared in commercial shrimp farms from white shrimp (first 2 years) to blue shrimp, as a consequence of viral disease outbreaks in the former species which impacted operations in Mexico in 1995 and 1996. Therefore, efficiency and productivity can be measured and the results can be analyzed in correspondence with three events: use of white or blue shrimp in operations; the effect of experience of working with one species after many years (white shrimp) and to initiate a learning curve with a new species (blue shrimp) after 1996; and the effect of the viral outbreak on production performance. Using an input distance function approach, total factor productivity (TFP) and technical efficiency (TE) using both traditional (T) and environmentally adjusted (EA) indicators were examined. TFP was reduced in 1996–1998 compared to 1994, due to a technological regression as reflected by increased input-intensive production technology resulting in an increase in undesirable outputs. The learning curve resulting from a shift from white shrimp to blue shrimp production species resulted in higher FCRs, water exchange and pollution emissions, despite increasing shrimp yields. In all years except 1994, EA TE and EA TFP were lower than the traditional TE and TFP scores. TE and TFP had an opposite behavior than yields in this period of time. In order to improve the technological change (TC) component of TFP in light of stable TE scores, increased government assistance in disseminating technological know-how is necessary to improve TFP at a faster rate during the transition period.

Guidelines for aquaculture effluent management at the farm-level

Pressure from environmental groups will force most governments to impose effluent regulations on aquaculture. Shrimp and fish producers are concerned that these regulations will be unnecessarily restrictive and expensive. Most pond aquaculture cannot be conducted without discharge. Fish and shrimp farms tend to be concentrated in specific regions, but typically they are sprawling operations where large volumes of relatively dilute effluents are released at many points. Effluents from pond aquaculture resemble non-point sources of pollution more than point sources. Thus, application of traditional effluent treatment methods to meet effluent standards, as done for point source pollution, will be difficult or impossible. Many involved in aquaculture believe that application of best management practices (BMPs) could be a reasonable and affordable way to improve the quality and reduce the volume of pond effluents. During recent years, several organizations have suggested systems of BMPs for making pond aquaculture more environmentally responsible. These include international development organizations (Food and Agriculture Organization of the United Nations and International Finance Corporation), industry groups (Global Aquaculture Alliance, Australian Prawn Producers Association, Marine Shrimp Culture Industry of Thailand, and Alabama Catfish Producers), a research center (Coastal Resources Center, University of Rhode Island), and state agencies in the USA (Missouri Department of Natural Resources and Florida Department of Agriculture and Consumer Services). The contents of BMP documents presented by the different groups are remarkably similar. Although the BMP approach is largely a “paper list” at present, the topic is being discussed widely, and producers are becoming more aware of environmental issues. There is an obvious attempt by producers in Latin America, Asia, Australia, and the United States to improve production practices, and some producers are voluntarily adopting BMPs. Many shrimp producers in several nations have installed settling basins, and a few large shrimp farms monitor effluent quality. The Aquaculture Certification Council (ACC) plans to implement a certification program based primarily on compliance with BMPs during 2003. There also is considerable discussion among producers and governmental agencies in several nations regarding BMPs, and it is expected that regulatory programs based on BMPs will be forthcoming.

Development and government policies of the shrimp farming industry in Thailand in relation to mangrove ecosystems

Intensive shrimp farming arrived in Thailand during the 1980s and developed virtually unregulated until 1987. Subsidised by the government, it quickly became an important export industry and Thailand has been the world's largest producer of tiger shrimp since 1991. However, the development of the shrimp farming industry in Thailand over the last 20 years in relation to its use of mangrove ecosystems is an example of sequential exploitation of natural resources witnessed through the shift in farm development from one region to another. This sequential exploitation has caused widespread degradation of mangrove ecosystems, and the benefits of the industry may be less than perceived as a result of subsidies and environmental and social impacts. This study follows the development of shrimp farming in Thailand from the 1940s to 1997 and studies national legislation and associated government policy as examples of driving forces behind this development. From our findings it appears that the development of legislation has not followed the same pace as the development of the industry, neither temporally, nor in content nor implementation, and contradictory policies have arisen.

Shrimp aquaculture: economic perspectives for policy development

The objective of this paper is to provide an overview of shrimp aquaculture from the perspectives of economics. It is offered as a contribution to the on-going policy debate on this globally important industry. The paper is organised into four sections: the benefits of shrimp aquaculture, the problems of shrimp aquaculture, economic development perspectives on shrimp aquaculture, and conclusions. Four main conclusions are drawn: there is a lack of independent analysis of the factors affecting the production strategies of private firms in the shrimp industry; there is a need to overcome polarisation in order to promote sustainable shrimp aquaculture; wider perspectives on shrimp aquaculture will be beneficial to policy formation; and it is in the long-run self-interest of shrimp producers to incorporate the external costs of production into planning decisions. The paper includes a review of the international literature which provides a valuable resource for policy-makers.

Detection of IHHN virus in shrimp tissue by digital color correlation

Shrimp culture has suffered from disease outbreaks that significantly affect the economy and restrain aquaculture production in many countries around the world. For research and diagnosis of shrimp diseases, histopathology is a powerful tool to identify pathogens and to understand the cellular, tissue and organ changes that result as a consequence of disease. One problem of the technique is that it requires considerable time, although shrimp producers demand results in the shortest possible time in order to take preventive or control measures. The introduction of techniques, such as processing of digital images in histopathology, could significantly reduce the time for precise diagnosis. Here, we present an attempt to implement this technique with infectious hypodermal and hematopoietic necrosis virus (IHHNV) because it presents difficulties for diagnosis by conventional histological techniques. In order to determine the viral histopathology that could be identified with the digital color correlation in different tissues, some very clear and conventional Cowdry type A inclusion bodies (CAIs) were selected. It was demonstrated that color digital correlation can be used to detect the virus IHHN in shrimp tissues. More researches are needed to be done, which consider several aspects, like rotation, scale, color, natural morphology of the virus and the use of different kinds of filters to determine whether the technique can be applied to other viruses.

Chemical and Physical Properties of Shrimp Pond Bottom Soils in Ecuador

AbstractChemical and physical analyses were conducted on bottom soil samples from 74 brackish‐water ponds representing 40 shrimp farms in Ecuador. Most ponds had soils with pH &gt; 6 and total carbon concentrations &lt; 2.5%. Carbon was mostly in organic form, for the average concentration of carbonate carbon was 0.06%. The C: N ratio was 8 to 10 in soils with &lt; 2.5% carbon. In ponds built in former mangrove areas, soil carbon was &gt; 2.5% and C: N ratios were 25 to 30. Ponds soils in former mangrove areas also tended to be high in total sulfur and low in pH. Lack of correlation between carbon and sulfur in mangrove soils suggested that most of the sulfur was inorganic and presumably in sulfides. Soils containing above 0.4% free carbonate (as equivalent CaCO3) had pH values &gt; 7. Although carbonate concentration was a major factor controlling soil pH, calcium hardness of pond waters was strongly influenced by salinity (and calcium) in the water supply. Total phosphorus concentrations averaged 898 mg/kg, and dilute acid extractable phosphorus usually accounted for 25–35% of the total. Concentrations of major cations and minor elements varied greatly in soils and exhibited ranges of up to three orders of magnitude. Contrary to opinions of shrimp producers, many pond soils in Ecuador are not acidic and few soils have a high organic matter content. Proper use of soil and water testing could greatly improve the efficiency of liming and other soil management practices.

Environmental Conditions and Pesticide Pollution of Two Coastal Ecosystems in the Gulf of California, Mexico

In December 1997 and April and September 1998, water temperature, salinity, dissolved oxygen, nutrients, chlorophyll, and pesticide residues were determined in two coastal ecosystems of Sinaloa, NW Mexico: Ensenada del Pabellón and Bahı́a de Santa Marı́a. These two are considered to be among the greatest shrimp producers in the region. Temperature, salinity, and dissolved oxygen were similar to those of other ecosystems of this region: high temperatures and salinity in spring and summer (dry season) and lower in winter and the rainy season. Levels of nitrites and phosphates and chlorophyll concentration were relatively higher than those of other ecosystems nearby, probably due to fertilizers used in the agricultural lands surrounding the water bodies studied. The pesticides more frequently detected were BHCα, aldrin, endosulfan and parathion. In some cases, pesticides forbidden by Mexican regulations were detected. These results indicate that the ecosystems studied are in a warning condition, because severe biochemical and physiological alterations have been reported in crustaceans exposed to pesticides. Therefore these pesticides could be one cause of the slow growth, diverse pathologies, and mortality in shrimp that have been reported in recent years.

Comparing Asian shrimp farming: the domestic resource cost approach

The technological advances of Asian shrimp farming systems have not only contributed to a rapid expansion of Asian shrimp culture, but have also created greater opportunities for foreign exchange earnings in the 1980s and 1990s. Current trends, however, indicate significantly increased competition in world shrimp markets with many Asian countries initiating or expanding shrimp culture. Oversupply of cultured shrimp products in the global market has already occurred in the early 1990s. Consequently, market prices of shrimp have dropped and profit margins have been squeezed by export markets. The purpose of this study is to estimate the degree of comparative advantage of Asian cultured shrimp countries in producing and exporting shrimp to Japan, the US and the EU (European Union) in 1994. First, cost comparisons of Asian shrimp farming technologies using intensive, semi-intensive and extensive systems among Thailand, Indonesia, Philippines, Malaysia, Viet Nam, India, Bangladesh, Sri Lanka, China and Taiwan are discussed. Next is an analysis of comparative advantage using the domestic resource cost (DRC) method, taking into account opportunity costs of not only input factors, but also the foreign exchange rate and the price of shrimp in the foreign market. Results show that nearly all Asian shrimp producers have greater comparative advantage in exporting shrimp to Japan than to the US and the EU markets, largely because of the premium shrimp prices received in the Japanese market. Moreover, Thailand, Indonesia and Sri Lanka have stronger comparative advantage relative to the other Asian countries studied. On the other hand, with high input costs, Bangladesh has a comparative disadvantage in exporting shrimp to the EU and US markets.

Microbiological quality of Icelandic cooked-peeled shrimp ( Pandalus borealis)

Iceland is a major producer of cold water shrimp, Pandalus borealis. In recent years considerable attention has been given to improve hygiene in the factories producing cooked, peeled and frozen shrimp. To keep track of the bacteriological status of the end product, shrimp from most of the factories is routinely analysed bacteriologically by the request of shrimp exporters. This paper reports on the results of a bacteriological analysis of 7913 samples of shrimp from 26 Icelandic factories over a 6-year period. The results showed that the geometric mean of APC (at 35°C) was 1718 per g and 57% of the samples had APC under 1000 per g. Some 70% of the samples had less than one coliform per g and 99.9% of the samples had less than one faecal coliform per g. Staphylococcus aureus was detected in less than 0.2% of the samples. The results show improvement in bacterial profiles, mainly total coliforms, over the 6-year period. Overall, the results show acceptable bacterial numbers in the finished product, indicating a high level of hygiene. Listeria spp. were, however, found in 270 of 3331 samples examined or 8.1%. Species identification was done on 49 of the 270 positive samples. The proportion of L. monocytogenes was found to be 26.5%.

Economic and water quality evaluation of intensive shrimp production systems in Thailand

Economic feasibility of five intensive shrimp production systems are evaluated using farm survey data for 20 contract farms and 31 independent farms in the Ranot District of Songkhla Province in southern Thailand. Generalized stochastic dominance (GSD) is applied to net economic returns to determine the rank order of the five production systems for farmers with different risk preferences. Water samples drawn from growout and sedimentation ponds and the ocean are tested for 12 water quality indicators. A production system used by independent farms is the most profitable system for all risk preferences evaluated. However, the system generates highly polluted wastewater. One production system used by contract farms provides the best overall quality of water, but has a low economic return. Not all production systems that improve water quality result in lower economic returns. Getting shrimp producers to adopt production systems that improve water quality will require effective regulations and/or economic incentives.

Export performance of major cultured shrimp producers in the Japanese and US markets

Increase in shrimp farming was stimulated by growth in world market for high-value shrimp products in the 1980s. The major cultured shrimp producers are located in Asia-Pacific and Latin American regions. The revealed comparative advantage (RCA) method is used to provide insights into the export performance of nine selected shrimp producers in the Japan and United States markets, separately. Shrimp is marketed in a wide variety of product forms, and prices vary according to various product attributes including species, size, taste, quality and origin. The results show that vertical product differentiation concerning different varieties of a good in terms of both quality and price plays an important role on the relative export competition of shrimp products among major shrimp-exporting countries. As a result of the geographical advantage, Asia-Pacific producers enjoy comparative advantage in the Japanese imported shrimp market. Joint ventures with the United States provide great benefits to Ecuador and Mexico in exporting fresh shrimp into the United States market.

Export performance of major cultured shrimp producers in the Japanese and US markets

Export performance of major cultured shrimp producers in the Japanese and US markets

Shrimp aquaculture development and the environment: People, mangroves and fisheries on the Gulf of Fonseca, Honduras

Beginning in the early 1980s, the Gulf of Fonseca in southern Honduras experienced a boom in aquaculture and became the second largest producer of farm-raised shrimp in the Western Hemisphere. Aquacultural development, however, has been accompanied by concern about: 1. (a) destruction of mangrove forest, 2. (b) depletion of fishing stocks, 3. (c) disappearance of seasonal lagoons, 4. (d) deteriorating water quality. We demonstrate that environmental degradation resulted from a multiplicity of causes including aquaculture, increasing numbers of fishermen, harmful agricultural practices, and poor governmental policies and regulation. We recommend immediate steps that should be taken to protect the natural environment and create a sustainable aquaculture.

Hydrocarbon concentrations in the American oyster, Crassostrea virginica, in Laguna de Terminos, Campeche, Mexico

Laguna de Terminos is a 2,500 km{sup 2} coastal lagoon in the southern Gulf of Mexico, located between 18{degrees} 20` and 19{degrees} 00` N, and 91{degrees} 00` and 92{degrees} 20` W (Figure 1). It is a shallow lagoon, with a mean depth of 3.5 m and connected to the Gulf of Mexico through two permanent inlets, Puerto Real to the east and Carmen to the west. Several rivers, most of them from the Grijalva-Usumacinta basin (the largest in Mexico and second largest in the Gulf of Mexico), drain into the lagoon with a mean annual discharge of 6 X 10{sup 9} m{sup 3}/year. This lagoon has been studied systematically, and is probably one of the best known in Mexico. An excellent overview of this lagoon can be found in Yanez-Arancibia and Day. The continental shelf north of Terminos, the Campeche Bank, is the main oil-producing zone in Mexico with a production of about 2 X 10{sup 6} barrels/day. It is also the main shrimp producer in the southern Gulf, with a mean annual catch of 18,000 tonnes/year, which represents 38 to 50% of the national catch in the Gulf of Mexico. The economic importance of this region, along with itsmore » extremely high biodiversity, both in terms of species and habitats, has prompted the Mexican government to study the creation of a wildlife refuge around Terminos. Thus, it is very important to know the current levels of pollutants in this area, as a contribution to the management plan of the proposed protected area. This paper looks at hydrocarbon concentrations in oyster tissue. 14 refs., 3 figs., 21 tabs.« less

Prospects for Promotion of ″Wild″ Shrimp in Japan: Implications for Australian Exporters

Since 1965 Japan has been a significant market for Australian “wild‐caught” shrimp taken from fisheries off northern Australia. Recent developments in shrimp culture, however, have resulted in the entry of high‐quality, lower‐priced shrimp into the Japanese market from North‐east and South‐east Asia, displacing the Australian product from its previously competitive position. Australian (and other) “wild” shrimp producers now face a situation of falling prices, rising costs, and dramatically different shrimp consumption and distribution patterns in Japan. The response of Australian producers has been to divert the product elsewhere to less “difficult” markets (e.g. the USA) and to form the Australian Prawn Promotion Association (APPA). The aim of this association is to implement a costly ($A1,000,000) promotional campaign in Japan aimed at Japanese consumers with the hope that it will reduce the price elasticity of demand for Australian product and allow producers to raise prices. Here, information gained from a review of the literature on primary product promotion, and primary data gained from interviews with “key informants” in the Japanese shrimp trade are used to assess the prospects of the proposal.