How does rainfall affect shrimp pond water parameters?

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Problems in shrimp farming usually occur during severe drought or heavy rainfall. Observations confim major losses occur mainly during periods of rainfall. In the last two years, we have had droughts brought about by El Niño. The US Climate Prediction Center and the International Research Institute for Climate and Society have issued an announcement that there is a 60% chance of La Niña developing in the last quarter of 2016. In contrast to El Niño, with La Niña we will [...]


Calcium, Magnesium Use In Aquaculture

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Summary: Aquatic plants and animals get the essential nutrients calcium and magnesium from water and their food. Hardness is usually great enough to supply adequate calcium and magnesium in fertilized ponds, and in ponds with feeding, they are obtained from feed when hardness is low. Calcium ions affect the toxicity of trace metals to aquaculture species. Although of limited concern in ponds, calcium carbonate precipitation can be troublesome in hatcheries. In inland waters, magnesium concentrations can be increased by [...]


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 [...]


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 [...]


Defining Ranges For Water Quality Variables Presents Complex, Challenging Process

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Summary: The creation and application of reference tables for acceptable concentration ranges of physical and chemical water quality variables for culture organisms would be challenging due to the differing tolerances found among the many farmed species. Factors such as water temperature, water chemistry (pH and dissolved oxygen and carbon dioxide levels), exposure time, physiological condition and size of the test animals can all affect tolerance. Especially in ponds, temperature and other water quality variables fluctuate on a daily basis, as [...]


Recirculating Aquaculture Technology – Part II. Starting Biofilters

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Summary: To start a biofilter together with a source of nitrifying bacteria, you must provide the conditions that will encourage the growth of the bacteria. The basic process requires initial preparation of water chemistry, adjustment of alkalinity to support bacterial growth and the addition of ammonia. Introducing nitrifying bacteria can accelerate the biofilter acclimation process. Ammonia, nitrite, pH, temperature and alkalinity levels should be monitored regularly in a standardized fashion. When starting a biofilter, it is very important to follow [...]


Copper Use In Aquaculture

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Summary: Copper is used for control of the blue-green algae responsible for off-flavors in aquaculture animals, treating diseases and parasites, and avoiding cage net fouling. Although copper is an essential nutrient for plants and animals, an excess can negatively affect the environment and human health. Copper concentrations decline very rapidly after pond treatments. The amount of copper in aquaculture products does not appear to be harmful to humans. Moreover, there is no evidence that copper treatments increase the copper [...]


Aquatic Animal Disease Report

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1. White Spot Disease (WSD) Pathogen: White spot syndrome virus (WSSV) Species affected: Penaeus monodon and Litopenaeus vannamei (10-85 DOC) Name of affected area: reported in 18 provinces (total area 7,279 ha) including Hai Phong, Quang Ninh, Nghe An, Ha Tinh, Quang Tri, Quang Binh, Quang Ngai, Thua Tien Hue, Phu Yen, Binh Dinh, Ho Chi Minh, Long An, Tien Gang, Ben Tre, Tra Vinh, Soc Trang, Bac Lieu and Ca Mau. Mortality rate: average to high, 100% in some cases within 10 d. Clinical signs: lethargic or moribund shrimps aggregated [...]


Utilization Of Ulva Lactuca Studied In White Shrimp Diets

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Summary: Research conducted by the authors studied whether fresh U. lactuca harvested weekly from a land-based integrated multi-trophic aquaculture system could be utilized as a nutritional supplement or partial replacement for pelleted feeds in the production of Litopenaeus vannamei. The study concluded that supplemental feeding of U. lactuca did not enhance growth, survival or feed conversion ratios. Partial replacement of pelleted feed with U. lactuca resulted in decreased growth, but did not affect survival or feed conversion. Shrimp fed readily on Ulva algae, but showed preference for pelleted feed during the experiment. Researchers at the Harbor Branch Oceanographic Institute [...]


Atmospheric Pollution Affects Water Quality

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Summary: Human activities have altered the concentrations of gases and other compounds in the atmosphere. Acid rain typically does not heavily affect aquaculture operations, and application of agricultural limestone can buffer water against the impacts of acid rain at facilities that use stream water. Due to higher carbon dioxide concentrations in the atmosphere, the amount of carbon dioxide that will dissolve in ocean water has increased. Decreased pH can thin the shells of some molluscan shellfish and reduce survival. Claude [...]