Trends in using sedimentation and filtration systems in intensive shrimp farming

(Baonghean) - Using a part of the pond area for water filtration in shrimp farming is a model implemented by many households in shrimp farming areas in Nghe An. This method contributes to improving the farming environment, bringing high efficiency in disease prevention, reducing risks for shrimp farming, a profession considered to be "money-making" in coastal areas.

Minimize risk, high efficiency

The family of Mr. Nguyen Van Khanh in Hamlet 6, Quynh Minh Commune (Quynh Luu) is considered a typical example of applying scientific and technological advances and dedicating a large area to make ponds to filter water. Starting to raise shrimp 5 years ago, Mr. Khanh initially used the entire area of ​​8 ponds to raise shrimp. However, this method does not have a drain pipe, but people go down to clean, suck the bottom water and take water directly from the Mai Giang River into the pond. As a result, the water environment is also polluted by waste that is not collected in one place but spread throughout the pond, greatly affecting the health of the shrimp.

“In 2015, I invested an additional 60 million VND to build basins between the ponds, dug and buried pipes in the middle, and installed a longer fan system to collect all the manure and waste discharged into the holding pond. At the same time, I selected the 3 largest ponds to make settling ponds to filter and treat the water before supplying it to the farming ponds. Currently, the pond water is very clean, there is no excess waste in the bottom of the pond, diseases such as red body, liver, and white feces have decreased by 70%, and shrimp productivity has increased 2-3 times. If previously, 8 ponds only yielded an average of 14-15 tons/crop, in the first crop this year, 5 ponds yielded 30 tons,” Mr. Khanh shared.

For the past two years, the shrimp pond environment of Mr. Nguyen Van Khanh's household in Quynh Minh commune (Quynh Luu) has been very clean thanks to investment in settling ponds. Photo: PH

Quynh Luu district has 650 hectares of brackish shrimp farming, concentrated in the communes of Quynh Bang, Quynh Luong, Quynh Minh and An Hoa. Overall, shrimp farming is still a highly effective profession. However, there are still many problems, many failed farming seasons, losses due to reasons related to breeds, infrastructure, food, water sources, etc.

Mr. Nguyen Anh Hung - Head of the Agricultural Extension Station of Quynh Luu district said: "We focus on building bio-safe shrimp farming models in key shrimp communes, in which we support 100% of the breed, 30% of the feed, medicine, microorganisms... to propagate and replicate. At the same time, we organize annual seminars and training sessions at the beginning and middle of the season to disseminate techniques, propagate and recommend people to apply advanced scientific and technological measures, including the use of settling and filtering ponds to isolate existing pathogens in the water environment, to ensure disease safety for shrimp.

Up to now, in the district, about 60% of shrimp farming area uses the 30 - 70 process (30% of the area is used as settling ponds); 25% has started to follow the 50 - 50 process according to the recommendations on safe biological shrimp farming (50% of the area is used as settling ponds); the remaining area is used at a lower level and a small part of the area does not have settling ponds but is taken directly from the river. Increasing the area for settling ponds has brought about clear results. In 2015, Quynh Luu's shrimp output reached 5,500 tons, and in the first crop of 2016 alone, it was 7,000 tons. Shrimp productivity in farming areas using settling ponds according to the correct process increased 2-3 times.

Hoang Mai town has 450 hectares of shrimp farming, concentrated in the localities of Quynh Di with 86 hectares, Quynh Lien with more than 53 hectares, Quynh Loc with more than 71 hectares... According to Mr. Nguyen Ngoc Thuy, Head of the town's Economic Department, the movement of reducing farming area to make settling ponds has developed strongly for several years now, up to now, nearly 100% of shrimp farming households use settling ponds with an average rate of 20 - 25% of the area for settling ponds, households that invest later spend up to 30 - 35%.

Inevitable trend

Nghe An currently has 1,350 hectares of shrimp farming, concentrated in Hoang Mai, Quynh Luu, Dien Chau, Nghi Loc and Vinh City. In recent years, to help people improve efficiency and limit risks in shrimp farming, the Fisheries Department has issued a separate process for safe shrimp farming, including instructions on designing and using ponds to filter water. Along with propaganda, recommendations and practical experience, in recent years, the water environment has become increasingly polluted, the weather has become more complicated, and people have become aware of this problem. Currently, 70% of the province's shrimp farming area has settling ponds, accounting for 25-30% (the settling pond area in the total farming area). However, according to Mr. Tran Xuan Quang - Deputy Head of Aquaculture Department, Nghe An Fisheries Sub-Department, only a few areas have achieved the ratio of 30 - 50 (30% of the area is used as settling ponds), while in areas supported by the CRSD Project, 90% of the area has settling ponds according to the recommended process; in the remaining areas, people only dig an additional small pond to make a settling pond or redesign it to be more reasonable and proactive in water supply.

Using settling ponds is an extremely important measure in intensive shrimp farming, especially in the current period when the water environment is increasingly polluted. Water is taken from outside into the settling pond, settled, filtered, and disinfected with chlorine and lime chemicals to ensure cleanliness, helping to proactively prepare water sources to supply to the pond when necessary, without causing fluctuations in the farming environment. According to the old process, the Fisheries industry recommends that settling ponds only account for 10 - 15% of the farming area. However, in the current conditions when diseases and environmental pollution increase, and biological products are abundant, the recommended ratio is increased to 30 - 40% of the area to be more proactive about water sources in conditions of prolonged heat and heavy rain.

“While climate change is increasingly affecting the water environment, hot weather causes water to evaporate quickly, settling ponds play a very important role in determining the success or failure of farming. Settling ponds are also places to filter heavy metals in water sources from seafood processing plants, pesticides in agriculture, especially when there is unseasonal rain and high tides. In particular, in disease prevention, settling ponds are an important measure to fundamentally solve this problem,” Mr. Tran Xuan Quang added.

Phu Huong