Key Technical Points and Detailed Farming Methods for High-Density Shrimp Farming
As the existing market demand for shrimp continues to increase, many shrimp farmers want to raise more shrimp within the same area, which has led to the emergence of high-density shrimp farming. So how exactly should you farm to produce high-yield and high-quality shrimp? Let's take a look together below.
High-Density Shrimp Farming Technology
Usually, open-air farming stocks about 50,000—100,000 shrimp per mu of water surface, while high-density shrimp farming indoors can achieve 500,000 shrimp per mu of water surface; under traditional farming methods, more than 50% of the water must be changed daily during the hot season, while high-density shrimp farming can go a full 4 months without changing the water at all; this high-density farming method has another advantage, which is that no drugs need to be administered. Excellent water quality is the key to shrimp farming. The biggest trick of the new shrimp farming method is creating an “artificial wetland” so that the water forms a self-purifying function. The “artificial wetland” consists of netting sheets hung vertically in the water like fishing nets, on which aquatic plants such as water grass are planted and materials that adsorb suspended solids in the water are hung. The biofilm formed on the netting sheets is equivalent to a “biological filter,” which can convert harmful substances in the water into harmless substances.
Another trick is that, with the help of several paddlewheel aerators, they create a “racetrack-style water flow” in the pond, which causes shrimp excrement and leftover feed to automatically sink to the bottom of the pond and fall into dedicated drainage ditches. At the same time, technicians must “blend” the natural river water, not only regulating salinity but also removing various harmful substances and killing some microorganisms. Then, during the shrimp's growth process, based on its molting condition, activity level, feeding amount, and so on, the feeding must be adjusted in a timely manner, and various indicators such as water temperature, light, and dissolved oxygen content must be regulated. If the shrimp do not get sick, there is no need to administer drugs. This intensive farming technology also has a simple model. Experts point out that farmers only need to invest in simple hardware equipment; the key lies in management. At present, this shrimp farming technology has entered the stage of industrialized farming in Shanghai, Tianjin, and Urumqi.
Profit of Farming Shrimp per Mu
Generally speaking, one mu of land can produce 500-600 jin of crayfish. If intensively farmed, the yield will be higher, but the corresponding investment will also be relatively larger. If it is below this number, it means you did not put in enough shrimp fry; the stocking density of shrimp fry and the size of the shrimp fry are related to the depth of the water. The stocking density of fry depends on the fry specification, the area of the shrimp pond, the depth of the pond water, the condition of the pond bottom, water exchange conditions, the type of bait, the rearing method, production skills, and management level, and should also be determined by referring to the yield requirements and specification indicators proposed by the shrimp farmer. The stocking amount can be calculated by referring to the following formula:
Stocking amount = (planned fry yield (kg) × number of shrimp required to grow 1 kg) / expected survival rate.
In the formula: the planned yield per mu can refer to the yields of neighboring areas in past years; the number of shrimp needed to grow 1 kg of shrimp can be calculated as 30-50 shrimp (body length 12-15 cm); the survival rate is calculated at 50%-70%, and for shrimp fry after intermediate rearing, it is calculated at 85%.
Under normal circumstances, for intensive shrimp ponds, under conditions of good shrimp fry quality, superior water exchange conditions, guaranteed bait, and a high level of rearing management, the stocking amount per mu can be about 20,000 shrimp (preferably not exceeding 25,000 shrimp). For shrimp fry that have undergone intermediate rearing (body length about 2.5 cm), the stocking amount per mu should be controlled between 8,000 and 12,000 shrimp.
Selection of Rice Fields for Shrimp Farming
1. Rice field selection: For rice fields, it is best to choose loam soil with abundant water sources, good water quality, a quiet surrounding environment, convenient irrigation and drainage, and convenient transportation. The water source should be a large, pollution-free water body. The field plot should not be affected by drought or flood disasters, the water quality should be fresh and pollution-free, the soil should be fertile but not silty, and the field ridges should be high (able to hold a water depth of 40-60 cm) and solid, without water leakage, with good water retention performance and ample sunlight.
2. Field construction: Field construction mainly includes widening, heightening, and reinforcing the field ridges. Filtering and escape-prevention facilities are installed at the water inlet and outlet, ring ditches and field ditches are excavated, and shade sheds are installed, etc. A ring ditch is dug around the rice field as a shrimp farming ditch, ensuring that the ring ditch is 3-5 m wide and 1.0 m deep. For larger field plots, a “field”-shaped or “well”-shaped field ditch should also be dug in the middle, with the field ditch width and depth being 1.0 m and 0.5 m respectively. The area of the ring shrimp farming ditch and the field ditch accounts for about 10% of the rice field area.
Stocking Technology for Crayfish
Crayfish fry stocking is divided into spring stocking and autumn stocking. The requirements are neat specifications, complete appendages, no disease or injury, and sufficient stocking in one go. Before stocking, bathe them in 5% salt water for 5-10 minutes to kill parasites and pathogenic bacteria. For purchased shrimp seed, because it has been transported long-distance out of water, before entering the pond, the fry should be soaked in the pond water for 1 minute, lifted out and set aside for 2-3 minutes, then soaked again for 1 minute, repeating this 2-3 times, so that the body surface and gill cavity of the fry absorb enough water before stocking, which can improve the survival rate. From the many years of experience of farmers, shrimp fry transported externally have a very low survival rate after long-distance transport. Properly polyculturing some silver carp and bighead carp in the pond can improve water quality and make full use of bait resources.
1. Spring stocking for grow-out shrimp: In mid-March, stock 5,000-6,000 juvenile shrimp with a body length of 3-5 cm.
2. Autumn stocking for broodstock rearing: Around September, stock 500 artificially selected crayfish broodstock per mu, with a male-to-female ratio of 3:1.
In fact, there are many shrimp farming techniques, and different people have achieved success using different methods. Therefore, on the road of shrimp farming, we cannot stick to convention but should reasonably find methods that suit us. In fact, experience is accumulated slowly through practice, and not everyone is destined to succeed from the very beginning.