Three-dimensional box-style farming techniques for swimming crab (Portunus trituberculatus) and yield per mu
Fresh swimming crab is one of the foods that many people love to eat, not only because its meat is tender and smooth with a full, delicious flavor, but also because its nutritional value is extremely high. As more and more people come to love swimming crab, it has become a new highlight among farming projects. So do you know how to farm swimming crab? How high is the annual yield of swimming crab?
Three-dimensional box-style farming techniques for swimming crab
1. Feeding
Swimming crab mainly feeds on animal-based bait; for large-scale farming, feeding low-value shellfish is best, followed by fresh mixed trash fish. For juvenile crabs weighing 0.8 g, the daily intake is 80% of body weight, and for individuals weighing 30 g, it is 20% of body weight. Combined with the actual practice of artificial swimming crab farming, the feeding amount and feeding time should be reasonably adjusted according to the growth needs of the swimming crab.
2. Water quality management
Ponds that are crystal clear to the bottom have a low survival rate. During the farming process, the water should be properly fertilized so that the pond water transparency is around 30 cm. In addition, water should be changed every day.
3. Separate rearing of males and females
Mixed rearing of males and females gives a very poor grow-out rate, and in winter the price of female crabs is more than 2 times higher than that of male crabs. Considering the different market values of male and female swimming crabs and the mutual influence between male and female swimming crabs during growth, in most cases, in order to improve the overall yield and sales value of swimming crab, males and females should be reared separately according to their different categories, so as to improve the farming results and benefits of swimming crab.
Swimming crab yield per mu
Assuming the survival rate of swimming crab is 70%, the size of finished crabs is 3.5 liang per crab, and the output per mu is 600 crabs, then the total yield per mu is 210 jin.
Assuming the pond-side price of swimming crab that year is 20 yuan per crab, based on a comprehensive estimate, the profit per mu is 2538 yuan. Of course, the above costs are only estimates; the specific profit also depends on the market conditions for swimming crab. Crab is a relatively widely distributed freshwater farming species in our country, with tender meat, a delicious taste, and extremely rich nutrition.
Preparation for swimming crab farming
1. Pond preparation: Pond preparation mainly involves removing excess sludge at the bottom of the pond, loosening and sun-drying the pond bottom, and also repairing supporting facilities such as pond embankments, sluice gates, and water channels.
2. Setting up obstacles: In order to make it easier for crab seedlings to rest and hide, after the pond is repaired, obstacles such as cement pipes, tiles, and bamboo tubes should also be placed at the bottom of the pond.
3. Cultivating bait: Half a month after pond clearing, the sluice can be opened to let water in. To prevent some harmful organisms from entering the pond, seawater can be filtered with 60-mesh silk bolting cloth. The pond water depth is generally kept at around 80 cm. After the pond is filled with water, chemical fertilizer should be applied to cultivate bait organisms, generally N fertilizer at 1.5 kg per mu and P fertilizer at 0.3 kg per mu, and the transparency of the pond water should be kept at around 30 cm.
Swimming crab farming management
1. Water quality management: In July, water should be changed once every 2 to 3 days; in August to September, once every 1 to 2 days; and in October, once every 4 to 5 days. The specific amount of water changed and the interval between water changes should vary according to environmental factors such as weather and water temperature.
2. Bait feeding: Swimming crab is an omnivorous crab, with fresh low-value fish, shrimp, shellfish, etc. as the main bait. The daily feeding amount should vary according to the size of the crabs. In the early stage of farming, feed about 8% of the total body weight of the crabs; in the middle stage, 12%; and in the later stage, 5%. When the water temperature drops to 10-15 degrees C in autumn, the daily feeding amount should be 3% of the total body weight, and feeding should follow the principle of feeding once in the morning and once in the evening, with less in the morning and more in the evening. When the daily average water temperature is below 10 degrees C, there is no need to feed bait.
3. Pond patrol management: Patrol the pond once in the morning and once in the evening. During patrols, carefully observe the feeding and activity of the swimming crabs, pay attention to changes in the pond water, check the condition of residual bait in the pond, and adjust the feeding amount and water exchange amount in a timely manner. Always pay attention to weather changes and do a good job in preparing for flood control and typhoon prevention. Frequently check whether the blocking nets at the sluice gates and the embankments are damaged or have leaks; if problems are found, repair them as soon as possible.
4. Timely harvest: Swimming crab should be harvested in late autumn. When the water temperature drops below 15 degrees C and the crabs no longer continue to gain weight, they should be harvested in time. Timely catching of swimming crab is the key to high quality, high efficiency, and high yield. The catching time should be decided according to whether the swimming crabs have entered the roe crab stage, the sales price, and weather conditions. Generally, it is best to arrange the catching time in December, and crabs should not be caught on rainy days. When only a small number of crabs are to be taken from the pond, they can be caught at night with crab cages or dip nets. When a large number are to be taken from the pond, net cage bags should be fixed at the sluice gate, and the ebbing tide should be used to release water so that the swimming crabs enter the cage bags with the current. When the water in the pond is drained to the lowest level, an iron rake can be used to slowly rake along the pond bottom. When a crab is encountered, lift it carefully and scoop it into a bamboo basket or bucket with a small dip net. The caught swimming crabs should have their two chelipeds bound with rubber bands to prevent them from biting each other or escaping from the bamboo basket or bucket.
As is well known, crabs have very strong adaptability, and in recent years the scale of crab farming has become larger and larger, bringing considerable economic benefits to many farmers. Therefore, if you want to start a farming business, farming swimming crab is a very good choice!