What are the precautions for stocking seed shrimp in rice-field shrimp farming?

The technique of farming shrimp in rice fields is now becoming more and more widely spread, and it has also tended to mature. Many people who have adopted the method of farming shrimp in rice fields have achieved very good returns, and the method of using one field for two purposes can maximize the role of the field!

Precautions for stocking seed shrimp in rice-field shrimp farming

1. Time for stocking seed shrimp. After the rice is harvested, water should be let in immediately to stock the seed shrimp. The stocking time is generally late September. For shrimp-farming rice fields, mechanical harvesting of the rice is preferable. This is because mechanical harvesting, first, is fast, which helps seize the time to stock the seed shrimp early;

Second, it helps return the rice straw to the field; mechanical harvesting threshes as it cuts, and the rice straw is spread evenly in the rice field, which helps the red swamp crayfish spread out in the rice field;

Third, the stubble height left by mechanical harvesting is relatively consistent (stubble of 40-50 is required), which helps control the water storage depth of the rice field.

After the rice is harvested, water should be let in immediately. The irrigation depth should preferably reach about 30cm at the field surface. When letting in water, a fine mesh net should be used to filter it, strictly preventing harmful organisms from entering. After the rice field stores water, seed shrimp should be stocked in time.     

Stocking density and stocking methods of seed shrimp     

1. Stocking density of seed shrimp: For stocking red swamp crayfish in rice fields, seed shrimp of different sizes can be stocked;

① Stock red swamp crayfish broodstock directly in the rice field and let them reproduce on their own. According to the actual situation of rice-field farming, if it is a rice field being farmed for the first year or for more than one year, about 15-25kg/mu of broodstock of about 30g each can be stocked; if it is a rice field that has been farmed for more than one year, then only 10-20kg/mu of broodstock of the above size needs to be stocked;

② Directly stock juvenile red swamp crayfish purchased from the market or caught manually. The general size is 250-600 individuals per kilogram. If it is the first year of farming, stock 10,000-15,000 individuals per mu; if it is a rice field that has been farmed for more than one year, stock 8,000-10,000 individuals per mu;

③ Stock shrimp fry artificially bred in the current year. The general size is 2-3cm, with a body weight of 1-2g. If it is a rice field in the first year of shrimp farming, stock 15,000-25,000 individuals per mu; if it is a rice field that has been farmed for more than one year, stock 10,000-15,000 individuals per mu.

2. Stocking methods of seed shrimp: When stocking red swamp crayfish, while paying attention to the quality of the seed shrimp, the same rice field should be stocked with seed shrimp of the same size, and they should be stocked all at once in sufficient quantity. Because red swamp crayfish individuals all have varying degrees of body surface damage when stocked, the shrimp bodies should be disinfected before stocking. If the seed shrimp are purchased from other places, because dry transport is used and the time out of water is relatively long, some shrimp may even appear comatose. Before stocking, the seed shrimp should be soaked in the rice field for 1 minute, lifted out and left for 2-3 minutes, then soaked again for 1 minute, repeating this 2-3 times, so that the body surface and gill cavities of the seed shrimp absorb enough water before stocking. This can effectively increase the survival rate of the seed shrimp.

Precautions for stocking seed shrimp     

1. After the rice is harvested, chickens, ducks, cattle and other livestock and poultry should be strictly prohibited from entering the rice field, to ensure that relatively abundant food is preserved in the rice field and to prevent pathogens from entering the rice field.

2. Strive to stock the seed shrimp early. Once the rice is ripe, it should be harvested in time, irrigated in time, and stocked in time. If it is a rice field in the first year of shrimp farming, because the renovation and construction of the rice field takes time, the stocking time may be delayed. Therefore, it is not suitable to stock broodstock seed shrimp; it is preferable to stock young shrimp or juvenile shrimp.    

3. The seed shrimp should not be stocked too concentratedly; they should be stocked evenly at separate points in the rice field, to avoid causing severe local oxygen deficiency in the water body and triggering suffocation and death of the seed shrimp.

4. The stocking time should be chosen in the morning or evening or on cloudy and rainy days, avoiding stocking under strong sunlight and high temperatures.

The growth environment of shrimp  

Shrimp swim very differently from fish. Fish can swim forward just by swinging their tail fins, but shrimp do not have tail fins like fish; they only have a tail and many small legs. So how do they swim? Shrimp also have their own “clever tricks.” Shrimp are skilled swimmers and can use their legs to swim long distances. When swimming, those swimming legs paddle backward frequently and neatly like wooden oars, and the body is slowly driven forward. When startled, its abdomen quickly bends and extends, and the tail paddles downward and forward, enabling it to leap backward continuously at a very fast speed. Some shrimp are also not good at swimming; lobsters mostly crawl on the sand and stones on the seabed for most of the time.  

Respiration and circulation: The gills of prawns are located in the gill chambers formed on both sides of the carapace, and the gill chambers communicate with the outside at the front, back, and ventral surface. The gills are mostly feather-shaped, 25 pairs in total, borne on the lateral walls of the thorax or the bases of the thoracic appendages. The epidermis is extremely thin, and gas exchange takes place when blood flows through the gills. In the gill chambers, the scaphognathites keep swinging, causing fresh water to enter from the rear and ventral surface and flow out forward. The circulatory system is open. The heart is a flat, polygonal muscular sac located in the pericardial sinus on the dorsal side of the cephalothorax, with 4 pairs of ostia: two pairs on the dorsal side, one pair on both sides of the posterior end, and the other pair on the ventral side of the heart near the posterior end, with valves controlling the direction of blood flow.

Although the technique of farming shrimp in rice fields is already quite mature, everyone can adopt it with confidence, but there are still many places that need attention. During the farming process, we should avoid unnecessary risks as much as possible, so as to maximize profits and create more wealth with the least effort!