Tag - pond bottom sludge

What Happens in Shrimp Ponds During Heavy Rains?

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• Water temperatures, oxygen, pH, alkalinity and salinity drop. • Phytoplankton crashes occur. • Organic material accumulates on pond bottoms. • Strong winds stir up the bottom sludge. • Toxic levels of hydrogen sulfide (H2S) are released. • Pathogenic bacteria replace beneficial bacteria. • The noise of rain pounding on the surface stresses the shrimp. • Shrimp molt because of the lower pH and phytoplankton changes. Outcomes: • Mortalities occur because of the changes in water quality, stress and pathogens. • Feed consumption drops. • Shrimp migrate to the bottom [...]


Shrimp Pond Waste Management – Approaches

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Increase in food production from fisheries sector led to introduction of noval technologies and intensive farming methods in shrimp culture that result in increased production of shrimp. Management of water and waste that produced is critical factor that has to be considered. In order to discharge waste water, some improved recirculating systems have been developed. But, the sludge has been neglected and posing a serious problem. So a systematic waste management strategy is needed which include treatment, disposal and [...]


Hydrogen Sulfide – The Silent Killer

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The March/April 2016 issue of AQUA CULTURE Asia Pacific, edited by Zuridah Merican (zuridah@aquaasiapac.com), contains an important article titled H2S –The Silent Killer, authored by Soraphat Panakorn (january161975@hotmail.com), a shrimp farming specialist at Novozymes Biologicals in Thailand. From Wikipedia: Hydrogen sulfide is the chemical compound with the formula H2S.  It is a toxic, colorless gas with the characteristic foul odor of rotten eggs.  It is heavier than air, very poisonous, corrosive, flammable and explosive.  Hydrogen sulfide often results from the [...]


Problems in shrimp culture during the wet season

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Recently, many farmers have faced the problem of fluctuations in salinity and temperature causing shrimp diseases; particularly yellowhead, white spot and luminescent bacteria that generally cause farmers to lose their crops. They have also had problems with stunted growth or black gill. Many of these problems can be overcome. Most farmers generally prefer to stock shrimp in the wet season, as they believe there are fewer problems than in the dry or cold seasons. However, culture in the wet season [...]


“Black spot” on shrimp

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Regulations prohibit the use of many chemicals and antibiotics in U.S. shrimp aquaculture. The FDA in Silver Spring, MD publishes a list of drugs approved for aquaculture, USFDA URL: http://www.fda.gov/AnimalVeterinary/DevelopmentApprovalProcess/Aquaculture/ucm132954.htm. The main commercial operations in the U.S. claim that they use chemicals and antibiotics responsibly and only when necessary. Although unsubstantiated, this claim is reinforced by limited or no disease occurrences in recent history in the U.S., negating the need for chemical use. Agricultural lime is used to control algal blooms [...]


Early Mortality Syndrome: Changing the Way We Farm

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Early Mortality Syndrome (EMS) has wreaked devastation across Asian shrimp farms over the past few years but now key research by Dr George Chamberlin, Global Aquaculture Alliance, and Dr Donald Lightner, University of Arizona, among others, is helping farmers adapt to living with and preventing EMS, writes Lucy Towers, The FishSite Editor. EMS is a bacterial disease of shrimp, characterised by an empty stomach, pale hepatopancreas and an empty midgut, which rapidly results in mass mortalities. The mass mortality caused by [...]


Some useful aspects on pond sediment PCR testing

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How to collect pond sediment for WSSV testing? Collect about half-a-kilo of sub surface sediment sample after scraping off about top 4-6 inches of sediment from four to five points especially in the wet patches within the pond including the area near the sluice gate. Pool all the samples, mix thoroughly and send about half- a kg of sediment to the laboratory in zip-lock bag taking care to avoid air within the cover. Should the sediment from all ponds in the farm be [...]


BMPs for prevention of WSD

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Pathogen exclusion or biosecurity is the only means of prevention of WSD at present. Disinfection of aquaculture facilities is a common disease management practice to ensure biosecurity. Methods for disinfection of aquaculture establishments have been outlined in OIE Aquatic Manual (2012). Following practice will help in ensuring biosecurity from WSSV. 1. Source water: Ideally farms must have reservoirs of adequate requirement of seawater for operation of aquaculture. Filter source water first through coarse screens to remove larger aquatic animals and debris and then pump into [...]


Ensuring WSSV Free Sediment and Water for Prevention of White Spot Disease

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The white spot syndrome virus (WSSV), the causative agent of white spot disease (WSD) of shrimp is an extremely virulent and most important cause of economic loss to the aquaculture sector. WSSV is widespread in shrimp aquaculture ecosystems globally and is transmitted vertically from infected broodstock to larvae and horizontally by ingestion of infected organisms. While WSD transmission vertically is being prevented by screening out infected broodstock, its horizontal transmission in grow out farms is a serious challenge. At present there is [...]


Species, Pond Size Define Aeration Approaches

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Summary: Each type of aerator has advantages and disadvantages. The combination of paddlewheel aerators and propeller-aspirator-pump aerators can be particularly effective in deep ponds. Diffused-air systems are most appropriate for small ponds. The amount of aeration can be increased as feeding rate increases to conserve energy. Aeration in shrimp ponds usually can be reduced from mid-morning until early evening. Research has demonstrated that considerable energy can be saved by using aerator automation systems. Claude E. Boyd, Ph.D., School of Fisheries, [...]