Using "river" technology to raise sturgeon in earthen ponds

This is a promising direction to help farmers overcome disadvantages in water resources, environment and investment costs.

The National Center for Freshwater Aquaculture in Central Vietnam uses “river” technology to successfully raise sturgeon in earthen ponds.

In Lam Dong, with favorable climatic conditions, sturgeon farming has been carried out for nearly 15 years with three main farming methods: running water farming in cement tanks, cage farming in reservoirs and running water farming in tarpaulin-lined ponds.

However, sturgeon farming is currently facing many difficulties. According to Mr. Nguyen Viet Thuy - Director of the National Center for Freshwater Aquaculture Breeding in the Central Region (located in Hiep Thanh Commune, Duc Trong District), one of the difficulties in developing sturgeon farming today is that the water resources in the upstream rivers and streams supplying sturgeon farming have almost been fully exploited. In addition, the reservoirs are also limited in scale due to environmental carrying capacity.

According to Mr. Thuy, sturgeon is a bottom-feeding species, with the habit of digging the bottom to find food, so it cannot be raised in earthen ponds, making the water cloudy and leading to fish deaths. Concreting the entire pond is costly, while the oxygen content in the still water pond is low, only low density can be raised, so it is not effective. Therefore, applying new technology such as the "river" model in the pond can overcome these difficulties to raise sturgeon in still water ponds and lakes in Lam Dong.

The technology of raising “river” aquatic products in ponds was developed in 2008, operating on the principle of creating a circulating water flow in the pond using an aeration system. In 2022, the Department of Science and Technology of Lam Dong province coordinated with the National Center for Freshwater Aquaculture in the Central region to implement the Project on Applying “river” technology in ponds to build a commercial sturgeon farming model suitable for the conditions of Lam Dong province.

The research subject is Siberian sturgeon (Acipenser baerii) from October 2022 to April 2023. The ponds applying the model have an area of 2,000 ^m2 /pond and the water level in the pond is maintained at about 1.7 m. The bottom of the pond is cleared of mud, leveled and dried. The pond bank is reinforced in the form of a slope, then covered with HDPE tarpaulin and a water supply and drainage system is installed for the pond.

The size of the ditch is designed with a length of 25 m, a width of 5 m, a depth of 1.8 m and is solidly built with concrete. The bottom of the ditch is 20 cm higher than the bottom of the pond and has a bottom slope of about 2% leaning towards the end of the ditch. The water level in the ditch is always guaranteed to be 1.5 m.

The National Center for Freshwater Aquaculture in the Central region has built a model with 3 ditches and raised at different densities including 10, 13, 16 fish/ ^m2 . The average temperature is about 22 degrees Celsius, the dissolved oxygen content is ensured by an aeration system. The aeration system also creates a flow through the ditches, creating an environment similar to natural water tank farming technology.

According to the analysis of the staff of the National Center for Freshwater Aquaculture in the Central region, in this system, excess food and fish waste are separated from the farming system, so there is no organic pollution. On the other hand, the self-treatment of the water environment in the pond, turning the pond into a stable and balanced ecosystem throughout the farming process, so the water source is absolutely proactive, not dependent on external water sources as well as water discharge to the outside, thereby controlling the quality of the environment, diseases inside and outside the farming system. The water environment factors in the sturgeon farming system using "river" technology in the pond are maintained stably throughout the farming cycle, suitable for the growth and development of sturgeon.

The “river” system in the pond can collect and completely remove waste deposited at the bottom of the ditch and completely treat the waste after collection. This helps keep the environment clean, without emitting substances that can affect the environment outside the system. The farming system including “rivers” and ponds becomes a typical ecosystem, always in balance during operation. In particular, it has the advantage of rarely changing water, so it can proactively source water, isolate diseases, adapt to climate change, and completely limit soil erosion and water pollution.

After 6 months of farming, the fish in the ditch with a density of 10 fish/ ^m2 reached the highest weight of over 0.9 kg/fish, the ditch with a density of 13 fish reached over 0.8 kg/fish, the density of 16 fish/ ^m2 had a weight of over 0.7 kg/fish. This is a relatively fast growth result, equivalent to farming models in natural water tanks and faster than the current cage farming model in reservoirs in Lam Dong.

Mr. Le Van Dieu - Deputy Director of the National Center for Freshwater Aquaculture in the Central region affirmed: "The "river" technology in the pond has a number of outstanding advantages, has a scientific basis, and is suitable for production practices. For example, the dissolved oxygen content in the water is high and stable throughout the farming process, the fish survival rate is from 80 - 90%. This model also manages and controls the environment, sorts fish sizes, and treats fish diseases easily. The harvesting of fish for meat is also proactive according to market demand".

Raising commercial sturgeon using "river" technology in ponds is a promising direction to expand the development of sturgeon farming in Lam Dong.

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