That is a promising direction to help farmers overcome unfavorable factors in terms of water sources, environment and investment costs.
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| The National Center for Freshwater Aquaculture in Central Vietnam uses "river" technology to successfully raise sturgeon in earthen ponds. |
In Lam Dong, with favorable climate conditions, sturgeon farming has been implemented for nearly 15 years with 3 main farming methods including: flowing water culture in cement tanks, cage farming on reservoirs and flowing water culture. in a tarpaulin pond.
However, the current sturgeon farming is facing many difficulties. According to Mr. Nguyen Viet Thuy - Director of the National Center for Freshwater Aquatic Breeds in Central Vietnam (located in Hiep Thanh Commune, Duc Trong District), one of the difficulties in the development of sturgeon farming today is the source of water in the coastal areas. Upstream rivers and streams that supply sturgeon farming have almost been exploited. In addition, the reservoirs are also limited in size due to the environmental capacity.
Also according to Thuy, sturgeon is a bottom-eating species, has the habit of digging through the bottom to find food, so it cannot be raised in earthen ponds, making the water cloudy, leading to fish death. Concreting the entire pond is expensive, while the oxygen content in the still water pond is low, only low density, so it is not effective. Therefore, the application of new technology such as the "river" model in the pond can overcome these difficulties to raise sturgeon in static ponds and lakes in Lam Dong.
The technology of "river" aquaculture in the pond was developed in 2008, operating on the principle of creating a circulating water flow in the pond by means of an aeration system. In 2022, the Department of Science and Technology of Lam Dong province in collaboration with the National Center for Freshwater Aquatic Breeds in the Central region to implement the Project of Applying "river" technology in ponds to build a suitable commercial sturgeon farming model. suitable with the conditions of Lam Dong province.
The study subjects were Siberian sturgeon (Acipenser baerii) with the period from October 10 to April 2022. The ponds applied in the model have an area of 4 m .2/pond and the water level in the pond is maintained around 1,7 m. The bottom of the pond is cleaned of mud, leveled and dried hard. The pond bank is reinforced in the form of a talus roof, then covered with HDPE tarpaulin and installed a water supply and drainage system for the pond.
The size of the farming ditch is designed with a length of 25 m, a width of 5 m, a depth of 1,8 m and solid concrete construction. The bottom of the ditch is 20 cm higher than the bottom of the pond and has a bottom slope of about 2% inclined towards the end of the ditch. The water level in the farming ditch is always guaranteed to be 1,5 m.
The National Center for Freshwater Aquatic Breeds in Central has built a model with 3 ditches and reared at different densities including 10 fish, 13 fish, 16 fish/mXNUMX.2. The average temperature is about 22 degrees Celsius, the dissolved oxygen content is ensured by the aeration system. The aeration system also creates a flow through the culture ditch, creating an environment similar to the technology of natural flowing water tank farming.
According to the analysis of the staff of the National Center for Freshwater Aquaculture in Central Vietnam, in this system, excess food and fish wastes 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 balanced ecosystem during the farming process, should be proactive in the absolute water source, not dependent on external water sources as well as discharge water. outside, thereby controlling environmental quality, diseases inside and outside the culture system. The water environment factors in the sturgeon farming system according to the "river" technology in the pond are maintained stably throughout the whole culture cycle, suitable for the growth and development of the sturgeon.
The "river" system in the pond can collect and thoroughly remove the waste deposited at the bottom of the ditch and completely treat the waste after collection. This helps to keep the environment clean, without emitting substances that can affect the environment outside the system. The farming system consisting of a “river” and a pond becomes a typical ecosystem, always in balance during operation. Especially, it has the advantage of less water change, so it is proactive in water sources, isolating diseases, adapting to climate change, and radically limiting soil erosion and water pollution.
After 6 months of culture, fish in the ditch are reared at a density of 10 fish/m .2 reached the highest weight with over 0,9 kg/head, the density of 13 fishes in the ditch was over 0,8 kg/head, the density of 16 fish/m2 weighing over 0,7 kg/head. This is the result of relatively rapid growth, equivalent to the culture models in natural flowing water tanks and faster than the current cage culture on reservoirs in Lam Dong.
Mr. Le Van Dieu - Deputy Director of the National Center for Freshwater Aquatic Breeds in Central Vietnam added: "The technology of "river" in ponds has a number of outstanding advantages, has a scientific basis, and is suitable for practice. manufacture. For example, the dissolved oxygen content in the water is high and stable throughout the culture process, the survival rate of fish reaches 80-90%. This model also manages and controls the environment, sizing fish, and handles fish diseases easily. The harvesting of fish meat is also proactive according to the needs of the market.”
Raising commercial sturgeon by "river" technology in ponds is a promising direction to replicate and develop sturgeon farming in Lam Dong.
