Trends in using sedimentation and filtration systems in intensive shrimp farming.

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

Minimize risks, maximize efficiency.

The family of Mr. Nguyen Van Khanh in Hamlet 6, Quynh Minh Commune (Quynh Luu District) is considered a prime example of applying scientific and technological advancements and dedicating a large area to water filtration ponds. Starting shrimp farming five years ago, Mr. Khanh initially used all eight ponds for shrimp farming. However, this method lacked drainage pipes; people manually cleaned and pumped water from the bottom of the ponds, drawing water directly from the Mai Giang River into the ponds. This resulted in water pollution from waste that wasn't collected in one place but scattered throughout the ponds, significantly impacting the health of the shrimp.

“In 2015, I invested an additional 60 million VND to create a basin between the ponds, burying pipes in the middle and extending the propeller system to collect all the manure and waste discharged into the holding pond. At the same time, I selected the three largest ponds to be used as settling ponds to filter and treat the water before supplying it to the rearing ponds. Currently, the pond water is very clean, there is no excess waste at the bottom of the ponds, diseases such as red body, liver disease, and white feces disease have decreased by 70%, and shrimp productivity has increased 2-3 times. While previously the 8 ponds only yielded an average of 14-15 tons per farming season, this year, the 5 ponds have yielded 30 tons,” Mr. Khanh shared.

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

Quynh Luu district has 650 hectares of brackish water shrimp farming, concentrated in the communes of Quynh Bang, Quynh Luong, Quynh Minh, and An Hoa. Overall, shrimp farming remains a highly profitable occupation. However, many shortcomings still exist, with numerous failed and unprofitable farming seasons due to issues related to shrimp fry, infrastructure, feed, and water sources.

Mr. Nguyen Anh Hung, Head of the Agricultural Extension Station of Quynh Luu District, said: “We focus on building bio-secure shrimp farming models in key shrimp-producing communes, providing 100% of the shrimp fry, 30% of the feed, medicine, and microorganisms… to promote and replicate them. At the same time, we organize annual workshops and training sessions at the beginning and middle of the season to disseminate techniques, promote and advise people to apply advanced scientific and technological measures, including the use of settling ponds to isolate existing pathogens in the water environment, ensuring disease safety for shrimp.”

To date, approximately 60% of the shrimp farming area in the district uses the 30-70 process (30% of the area is used for settling ponds); 25% has started following the 50-50 process in accordance with recommendations for biosecure shrimp farming (50% of the area is used for settling ponds); the remaining areas either use a lower level of settling ponds or a small portion of the area does not have settling ponds and draws directly from the river. The increase in the area used for settling ponds has yielded significant results. In 2015, Quỳnh Lưu's shrimp production reached 5,500 tons, while in the first crop of 2016 alone it reached 7,000 tons, with shrimp yields in areas using settling ponds according to proper procedures increasing 2-3 times.

Hoang Mai town has 450 hectares of shrimp farming area, concentrated in the localities of Quynh Di (86 hectares), Quynh Lien (over 53 hectares), and Quynh Loc (over 71 hectares)... According to Mr. Nguyen Ngoc Thuy, Head of the Economic Department of the town, the movement to reduce farming area to build settling ponds has developed strongly in recent years. To date, almost 100% of shrimp farming households use settling ponds, with an average rate of 20-25% of the area dedicated to settling ponds, and those who invested later allocating up to 30-35%.

An inevitable trend

Nghe An province currently has 1,350 hectares of shrimp farming area, concentrated in Hoang Mai town, Quynh Luu, Dien Chau, Nghi Loc districts and Vinh City. Over the years, to help people improve efficiency and reduce risks in shrimp farming, the Fisheries sector has issued a specific procedure for bio-secure shrimp farming, including guidance on designing and using settling ponds for water filtration. Along with propaganda, recommendations, and lessons learned from practice, in recent years, with increasing water pollution and complex weather patterns, farmers have become more aware of this issue. Currently, 70% of the province's shrimp farming area has settling ponds, accounting for 25-30% (the area of ​​settling ponds in the total farming area). However, according to Mr. Tran Xuan Quang, Deputy Head of the Aquaculture Department of the Nghe An Fisheries Sub-Department, only a few areas achieved a rate of 30-50% (30% of the area used for sedimentation ponds). In areas supported by the CRSD Project, 90% of the area has sedimentation ponds following the recommended procedures; in the remaining areas, people only dug an additional small pond to use as a sedimentation pond or redesigned it for better efficiency and more proactive water supply.

Using settling ponds is an extremely important measure in intensive shrimp farming, especially in the current period when water environments are increasingly heavily polluted. Water is drawn from outside into the settling pond, settled, filtered, and treated with chlorine and lime to disinfect, ensuring cleanliness and proactively preparing a water source for the rearing ponds when needed, without causing fluctuations in the farming environment. According to the old process, the Fisheries sector recommended that settling ponds only occupy 10-15% of the farming area. However, in the current conditions with increased disease outbreaks, environmental pollution, and the availability of biological products, the recommended percentage is increased to 30-40% of the area to better manage water resources during prolonged hot weather or heavy rains.

“While climate change is increasingly affecting the aquatic environment, and the heat causes rapid water evaporation, settling ponds play a crucial role in determining the success or failure of a farming season. Settling ponds also filter out heavy metals from water sources due to seafood processing plants, pesticides in agriculture, especially during unseasonal rains and tidal surges. In particular, in disease prevention, settling ponds are an important measure to fundamentally address this issue,” Mr. Tran Xuan Quang added.

Phu Huong