Commercial Shrimp Farms Research Articles

Evaluation of biosecurity applications for intensive shrimp farming

In the past decade, viral diseases have had a profound and global effect on commercial shrimp farming. Regional farming industries in both hemispheres have suffered economically significant and prolonged viral epidemics resulting in declining shrimp farm production and even collapse. Ozone applications have been extensively examined as a means of disinfection and general disease control in relatively small hatchery systems and experimental intensive fish production systems. However, applications for large outdoor ponds typical of commercial shrimp culture have been generally considered infeasible despite the unique properties of ozone to deactivate viruses. This paper examines the experiences of operating a large-scale ozone application and complementary biosecurity measures for shrimp production in outdoor ponds suggesting design criteria for improved biosecurity. This paper includes a financial simulation of an intensive shrimp production system incorporating mechanical aeration, recirculation, filtration, treatment ponds, and ozone contact. The implications of the financial model are evaluated.

Economic and demographic factors affecting mangrove loss in the coastal provinces of Thailand, 1979-1996.

The following paper analyzes the economic and demographic factors determining the conversion of mangroves in the coastal provinces of Thailand to commercial shrimp farming. Mangrove conversion therefore is determined by the returns to shrimp farmers, (i.e. the price of shrimp), the input costs to farming shrimp (e.g. feed price and wages) and the "accessibility" of mangrove areas. Additional exogenous influences, such as income per capita, population growth, and in-migration (i.e. the number of shrimp farms) also are important. Both a mangrove conversion and a shrimp farm expansion relationship are estimated empirically through a panel analysis across 21 coastal provinces of Thailand between 1979-1996. Results show that the price of shrimp, minimum wage, distance from market, feed price, population growth, income per capita, and shrimp-farm density all have important influences on mangrove loss due to shrimp farming in Thailand.

Review of Some Recent Developments in Sustainable Shrimp Farming Practices in Texas, Arizona, and Florida

The world shrimp-farming industry is currently experiencing major crop losses due to disease outbreaks, which are often associated with environmental degradation. Such losses can be minimized through the adaptation of technologies that enhance biosecurity and environmental control. Current technologies suggest that a shrimp yield as high as 10 kg/m2/crop can be achieved in indoor, super-intensive, closed-recirculation systems in which environmental parameters are controlled. Nevertheless, high construction and operating costs make the financial viability of these systems questionable. Production of shrimp with reduced water exchange in outdoor ponds is another promising method to minimize monetary losses and environmental degradation. Data from commercial shrimp farms in south Texas suggest that significant reduction in water exchange and nutrient release is feasible with no impact on production when an adequate level of aeration is provided. Researchers of the Texas Agricultural Experiment Station, Corpus Christi, Texas, are currently testing other potential management tools for intensification of outdoor pond productions. These trials demonstrated the feasibility of producing ayield of almost 0.9 kg/m2 of marketable size shrimp with no water exchange. Inland production of shrimp in low-salinity ground water can provide another potential solution to disease and environmental problems, as production is conducted in isolated areas away from other host species and where effluent water can be used for crop irrigation. Recent studies with this water showed that high-density nursery and grow-out of Pacific white shrimp, Litopenaeus vannamei are feasible, with excellent survival and yield.

Ecological Conflicts and Valuation: Mangroves versus Shrimps in the Late 1990s

Shrimp are harvested in two different ways. They are fished in the sea (sometimes to the cost of turtles) or they are ‘farmed’ in ponds in coastal areas. Such aquaculture is increasing around the world as shrimp become a valuable item of world trade. Mangrove forests are sacrificed for commercial shrimp farming. The author considers the conflict between mangrove conservation and shrimp exports in different countries. Who has title to the mangroves, who wins and who loses in this tragedy of enclosures? Which languages of valuation are used by different actors in order to compare the increase in shrimp exports and the losses in livelihoods and in environmental services? The economic valuation of damages is only one of the possible languages of valuation which are relevant in practice. Who has the power to impose a particular language of valuation?

USE OF AN EDIBLE RED SEAWEED TO IMPROVE EFFLUENT FROM SHRIMP FARMS

Nelson, S. G.1, Glenn, E. P.1, Moore, D.1, Walsh, T,2 & Fitzsimmons, K. M.1 1Environmental Research Lab, University of Arizona, 2601 E. Airport Dr. Tucson, AZ 85706 USA; 2SOEST Analytical Services Laboratory, University of Hawaii‐Manoa, Honolulu, HI 96822 USAAn integrated shrimp and seaweed farm in Hawaii demonstrates the advantages of using algae to improve effluent quality from animal aquaculture operations. Gracilaria parvispora grown in the effluent channel of a commercial shrimp farm (Penaeus vannamei) absorbed significant quantities of nitrogenous and other waste compounds. Wild populations of the edible red seaweed were transferred into the effluent channel and grew at a Relative Growth Rate of 4.7% per day and increased it's nitrogen content from 1% to 3%. The weekly harvest of 100 kg from the effluent canal represented a removal of 3 kg of nitrogen from the effluent stream. An additional benefit was that seaweed could be fertilized in the ditch. Stocks of seaweed placed in the effluent ditch for five days would increase their nitrogen content from 1% to 3% and C:N ratio changed from 30:1 to 10:1. These algae would then be placed in cages in the ocean and would achieve growth rates of 9% per day compared to inorganically fertilized algae with RGR of 4.6% and unfertilized algae with RGR of 1.7%. Inorganic fertilizers that were formulated to mimic the concentrations in the effluent canal could not support the growth rate of the organic fertilization, implying that some micro‐nutrients or other factors were benefiting the algae growth.

VALUING MANGROVE CONSERVATION IN SOUTHERN THAILAND

Mangroves are ecologically important coastal wetland systems that are under severe threat globally. In Thailand, the main cause of mangrove conversion is shrimp farming, which is a major source of export income for the country. However, local communities benefit from many direct and indirect uses of mangrove ecosystems and may have a strong incentive to protect these areas, which puts them into direct confrontation with shrimp farm operators and, by proxy, government authorities. The article examines whether or not the full conversion of mangroves into commercial shrimp farms is worthwhile once the key environmental impacts are taken into account. The estimated economic value of mangrove forests to a local community is in the range of $27,264‐$35,921 per hectare. This estimate includes the value to local communities of direct use of wood and other resources collected from the mangroves as well as additional external benefits in terms of off‐shore fishery linkages and coastline protection from shrimp farms. The results indicate that, although shrimp farming creates enormous private benefits, it is not so economically viable once the externalities generated by mangrove destruction and water pollution are included. There is also an incentive for local communities to protect mangroves, which in turn implies that the rights of local people to guard and protect this resource should be formally recognized and enforced by law.

Valuing mangrove conservation in Southern Thailand

Mangroves are ecologically important coastal wetland systems that are under severe threat globally. In Thailand, the main cause of mangrove conversion is shrimp farming, which is a major source of export income for the country. However, local communities benefit from many direct and indirect uses of mangrove ecosystems and may have a strong incentive to protect these areas, which puts them into direct confrontation with shrimp farm operators and, by proxy, government authorities. The article examines whether or not the full conversion of mangroves into commercial shrimp farms is worthwhile once the key environmental impacts are taken into account. The estimated economic value of mangrove forests to a local community is in the range of $27,264-$35,92l per hectare. This estimate includes the value to local communities of direct use of wood and other resources collected from the mangroves as well as additional external benefits in terms of off-shore fishery linkages, and coastline protection from shrimp farms. The results indicate that, although shrimp farming creates enormous private benefits, it is not so economically viable once the externalities generated by mangrove destruction and water pollution are included. There is also an incentive for local communities to protect mangroves, which in turn implies that the rights of local people to guard and protect this resource should be formally recognized and enforced by law.

Integrated treatment of shrimp effluent by sedimentation, oyster filtration and macroalgal absorption: a laboratory scale study

Effluent water from shrimp ponds typically contains elevated concentrations of dissolved nutrients and suspended particulates compared to influent water. Attempts to improve effluent water quality using filter feeding bivalves and macroalgae to reduce nutrients have previously been hampered by the high concentration of clay particles typically found in untreated pond effluent. These particles inhibit feeding in bivalves and reduce photosynthesis in macroalgae by increasing effluent turbidity. In a small-scale laboratory study, the effectiveness of a three-stage effluent treatment system was investigated. In the first stage, reduction in particle concentration occurred through natural sedimentation. In the second stage, filtration by the Sydney rock oyster, Saccostrea commercialis (Iredale and Roughley), further reduced the concentration of suspended particulates, including inorganic particles, phytoplankton, bacteria, and their associated nutrients. In the final stage, the macroalga, Gracilaria edulis (Gmelin) Silva, absorbed dissolved nutrients. Pond effluent was collected from a commercial shrimp farm, taken to an indoor culture facility and was left to settle for 24 h. Subsamples of water were then transferred into laboratory tanks stocked with oysters and maintained for 24 h, and then transferred to tanks containing macroalgae for another 24 h. Total suspended solid (TSS), chlorophyll a, total nitrogen (N), total phosphorus (P), NH 4 +, NO 3 −, and PO 4 3−, and bacterial numbers were compared before and after each treatment at: 0 h (initial); 24 h (after sedimentation); 48 h (after oyster filtration); 72 h (after macroalgal absorption). The combined effect of the sequential treatments resulted in significant reductions in the concentrations of all parameters measured. High rates of nutrient regeneration were observed in the control tanks, which did not contain oysters or macroalgae. Conversely, significant reductions in nutrients and suspended particulates after sedimentation and biological treatment were observed. Overall, improvements in water quality (final percentage of the initial concentration) were as follows: TSS (12%); total N (28%); total P (14%); NH 4 + (76%); NO 3 − (30%); PO 4 3− (35%); bacteria (30%); and chlorophyll a (0.7%). Despite the probability of considerable differences in sedimentation, filtration and nutrient uptake rates when scaled to farm size, these results demonstrate that integrated treatment has the potential to significantly improve water quality of shrimp farm effluent.

Impact of culture intensity and monsoon season on water quality in Thai commercial shrimp ponds

The present authors investigated the impact of farming intensity and the prevailing season on water quality in intensive tropical shrimp farms. The weekly water quality samples from the inlets and production ponds of two commercial shrimp farms operating partial water exchange schedules and representing low and high farming intensities in Thailand (with Penaeus monodon Fabricius production rates of 4 and 9 t ha ‐1 cycle ‐1 , respectively) were analysed over two consecutive production cycles, covering the wet (monsoon) and dry seasons. Significant differences in inlet water quality between farms occurred only in salinity, temperature and suspended solids. The present authors assessed impacts of farming intensity and season on production pond water quality parameters using: (1) an analysis of variance (ANOVA) of measurements in replicate ponds during the final month of the production cycle; and (2) a trend analysis which classified trends in parameters over the cycle as externally or internally determined. The prevailing season was found to have a strong impact on salinity, temperature, pH, nitrate, dissolved reactive phosphorus, total phosphorus and dissolved oxygen in the final month of the cycle. The trends in these parameters were largely externally determined or absent. Nitrite and chlorophyll a were affected by production intensity in interaction with season and showed mainly internally determined trends. This indicates that nitrogen transformation processes responded to input levels as well as seasonal influences. Ammonia was highly variable and no significant intensity or season effects were detected, but trends were internally determined only at high intensity and more pronounced in the dry rather than the wet season. The results indicate strong seasonal effects on water quality in tropical shrimp ponds, direct in some parameters and indirect in others, including those linked to nitrogen transformations. The mechanisms of seasonal variation and the implications of these changes for water quality management call for further investigation.

Modelling growth rate of Penaeus monodon Fabricius in intensively managed ponds: effects of temperature, pond age and stocking density

Records of shrimp growth and water quality made during 12 crops from each of 48 ponds, over a period of 6.5 years, were provided by a Queensland, Australia, commercial shrimp farm. These data were analysed with a new growth model derived from the Gompertz model. The results indicate that water temperature, mortality and pond age significantly affect growth rates. After 180 days, shrimp reach 34 g at constant 30 °C, but only 15 g after the same amount of time at 20 °C. Mortality, through thinning the density of shrimp in the ponds, increased the growth rate, but the effect is small. With continual production, growth rates at first remained steady, then appeared to decrease for the sixth and seventh crop, after which they have increased steadily with each crop. It appears that conservative pond management, together with a gradual improvement in husbandry techniques, particularly feed management, brought about this change. This has encouraging implications for the long-term sustainability of the farming methods used. The growth model can be used to predict productivity, and hence, profitability, of new aquaculture locations or new production strategies.

Modelling growth rate of Penaeus monodon Fabricius in intensively managed ponds: effects of temperature, pond age and stocking density

Records of shrimp growth and water quality made during 12 crops from each of 48 ponds, over a period of 6.5 years, were provided by a Queensland, Australia, commercial shrimp farm, These data were analysed with a new growth model derived from the Gompertz model. The results indicate that water temperature, mortality and pond age significantly affect growth rates. After 180 days, shrimp reach 34 g at constant 30 degrees C, but only 15 g after the same amount of time at 20 degrees C. Mortality, through thinning the density of shrimp in the ponds, increased the growth rate, but the effect is small. With continual production, growth rates at first remained steady, then appeared to decrease for the sixth and seventh crop, after which they have increased steadily with each crop. It appears that conservative pond management, together with a gradual improvement in husbandry techniques, particularly feed management, brought about this change. This has encouraging implications for the long-term sustainability of the farming methods used. The growth model can be used to predict productivity, and hence, profitability, of new aquaculture locations or new production strategies.

Impact of farming intensity and water management on nitrogen dynamics in intensive pond culture: a mathematical model applied to Thai commercial shrimp farms

A mathematical model is used to investigate the impact of farming intensity and water management on nitrogen dynamics in the water column of intensive aquaculture ponds. The model describes the input of ammonia, its assimilation by phytoplankton or nitrification, and the loss of nitrogen through sedimentation, volatilization, and discharge. The model is calibrated for two commercial shrimp (Penaeus monodon Fabricius) farms in Thailand. Assimilation by phytoplankton with subsequent sedimentation or discharge is the principal process of ammonia removal. When inputs of ammonia exceed the algal assimilation capacity (carrying capacity), nitrification and volatilization of excess ammonia become significant. Carrying capacity is negatively affected by non-chlorophyll turbidity, and was estimated as 6 t ha−1 cycle−1 at a non-chlorophyll extinction of 2.6 m−1. In ponds managed within their carrying capacity, ammonia concentrations are lowest at no water exchange, reach a maximum at exchange rates between 0.2 and 0.4 day−1, and decline again at higher rates. When the carrying capacity is exceeded, excess ammonia concentrations decline continuously with increasing water exchange. Average exchange rates used in intensive shrimp farms (up to 0.2 day−1) reduce phytoplankton abundance and sedimentation within ponds, but not ammonia concentrations. Discharges are high in particulate nitrogen at water exchange rates up to 0.3 day−1, but contain mainly dissolved nitrogen at higher rates.

Impact of farming intensity and water management on nitrogen dynamics in intensive pond culture: a mathematical model applied to Thai commercial shrimp farms

Impact of farming intensity and water management on nitrogen dynamics in intensive pond culture: a mathematical model applied to Thai commercial shrimp farms

Food ingestion and assimilation by the southern brown shrimp Penaeus subtilis under semi-intensive culture in NE Brazil

In recent years in NE Brazil, attempts to increase productivity in extensive marine shrimp farms has focused attention on semi-intensive cultivation methods with native species. The present study was initiated to investigate the diet of Penaeus subtilis under semi-intensive conditions over a complete growth cycle. The experiment was conducted at a commercial shrimp farm on the NE Brazilian coast. The investigation focused on the analysis of stomach contents and stable carbon isotope ratios. Naturally occurring pond biota was the major food source for P. subtilis observed throughout the study. Formulated food constituted 15.61% of the stomach contents (5.99% of stomach volume), accounting for 24.91% of the carbon growth, with the remainder attributed to natural food (average 75.09%). Polychaetes were the most important food type, representing 80.83% of all prey ingested (32.55% of the total food consumed). In the initial growth stages, P. subtilis displayed pronounced detritivorous feeding behaviour. As the shrimp grew, prey organisms were consumed in greater amounts, revealing a more carnivorous habit. Overall, a benthic omnivorous opportunist feeding behaviour was observed.

Environmental Impacts of Shrimp Farming with Special Reference to the Situation in the Continental United States

Shrimp culture technology has resulted in development of a major shrimp farming industry worldwide. Without the shrimp farming industry, increasing demands for shrimp by consumers could not be met, resulting in increased pressure on wild shrimp resources. Unfortunately, there are realized and potential adverse environmental effects on estuarine ecosystems as a result of shrimp farming. The effects can be categorized as wetland destruction for construction of shrimp farms, hypernutrification of estuarine ecosystems by shrim pond effluent, “biological pollution” of native shrimp stocks through escapement of aquaculture stocks, water use and entrainment of estuarine biota, and impacts of shrimp farm chemicals on estuarine systems. While the shrimp farming industry in the United States is small, the United States is effectively addressing all the realized and potential environmental impacts through regulation and research at the federal and state levels. Areas of regulation and research include stringent prohibitions on wetland destruction, regulation of effluents and support of research to eliminate and/or reduce effluents, escapement prevention technology and development of high-health stocks, minimizing entrainment of estuarine biota through water conservation and screening technology, and regulation of chemical use in the shrimp farming industry and support of research on shrimp pathology and environmentally safe disease control. Work is still in progress and not all problems have been resolved to the complete satisfaction of shrimp farmers and estuarine conservationists. However, the situation in the United States should serve as a model of how to encourage sustainable economic development through commercial shrimp farming while abating adverse environmental impacts on estuarine systems. To further improve the situation, the development and adoption of “best management practices” for shrimp aquaculture are recommended.

An epizootic of necrotizing hepatopancreatitis in cultured penaeid shrimp (Crustacea: Decapoda) in northwestern Peru

In January and February of 1993 a severe epizootic of necrotizing hepatopancreatitis (NHP) began to affect a number of commercial penaeid shrimp farms in the Tumbes area of northwestern Peru and adjacent areas of Ecuador. Histological and transmission electron microscopical (TEM) examination of affected juvenile Penaeus vannamei showed massive infections of the hepatopancreas by a pleomorphic intracellular Gram-negative bacterium. The agent was named Peru NHP (PNHP) for its geographical occurrence and for the type of lesion with which it was associated. A very similar bacterium (TNHP) has been found to be associated with a serious epizootic disease in shrimp farms in Texas. Before the cause of the Peru epizootic of PNHP was determined and corrective measures were taken, nearly half of Peru's 44 active shrimp farms had been so seriously affected that they were closed by June of 1993.

Hermaphroditism in the penaeid shrimp Penaeus vannamei (Crustacea: Decapoda: Penaeidae)

Two hermaphroditic Penaeus vannamei were found among a group of F 4 broodstock cultured at a shrimp farm in Venezuela. These shrimp described herein are the first reported penaeoids known to possess a thelycum, petasma, appendix masculina, ovaries, testes, and the genital apertures of both sexes. The male and female gonopores are normal; the thelyca are similar to that of normal females; the petasmata and appendices masculinae are smaller than normal and with atypical shape; the ovaries and testes are much reduced, but histological preparations reveal that the tissues are typical of normal shrimp. No evidence of parasitism was found in the specimens, nor is any other factor apparent that may have induced these abnormal sexual features. Since the specimens were found at a commercial shrimp farm, perhaps this occurrence of hermaphroditism is in some way linked to condition (s) encountered during the culture of penaeid shrimp in captivity.

Morphological evidence for a single bacterial etiology in Texas necotizing hepatcpanceatitis in Penaeus vannamei (Crustacea. Decapoda)

Morphological evidence for a single bacterial etiology in Texas necotizing hepatcpanceatitis in Penaeus vannamei (Crustacea. Decapoda)

Maturation and Spawning of the White ShrimpPenaeus schmittiBurkenroad, 1936, Under Large Scale Rearing Conditions

AbstractThis paper describes the reproductive performance ofPenueus schmittikept under controlled conditions in a maturation facility of a commercial shrimp farm. A total of 369 females and 368 males of wildP. schmittiwere used to form 9 broodstock groups. Unilateral ablation was performed on females only. Although females were not tagged, the total number of mated females (N =533) indicates that rematuration of the ovaries did occur. Only 9 mated females (1.69%) did not spawn and only 22 mated females (4.20%) of the remaining 524 cases did not produce viable spawns. These results indicate that a large number of viable spawns (94.18%) can be expected fromP. schmitti. A minimum latency period of 6 days for the ovaries to attain full development was observed twice. The highest mating frequency occurred between the 46th and 60th days after unilateral ablation, but mating frequency remained above 2% until the 90th day. The average number of nauplii/female/spawn was 78,961 (N =524) and the average fertilization rate of the eggs was 73.12% (N =297). Usually when the pair of the spermatophores is dislodged from the thelycum of the mated female, a small sperm mass still remains between the third pair of walking legs. This condition did not show any negative effect on the fertilization rate of the eggs and nauplii production. Mating behavior displayed byP. schmittiis also described and includes three distinctive phases: a) chasing, b) mating and c) post‐mating chase.