For the majority of farmers, the scientific and reasonable density of captive crabs in spring is very important, which directly affects the specifications, output and sales price of adult crabs harvested in autumn. Take the wholesale price of Panjin river crab in Hujia market on September 9th, three days before Mid-Autumn Festival in 20 1 1 year as an example.100g-120g (that is, full two females) is 55 yuan, while 75g-99g (that is, full one and two females). With the maturity and rationality of consumption, the sales price caused by the difference of Panjin crab specifications will become more and more obvious, and the final benefits of different crab farmers will also be obviously divided. Many enthusiastic people who first came into contact with the culture of Panjin crab called to ask related questions. At the same time, they also noticed that some unscrupulous vendors instructed the farmers on the incredible culture density in order to sell more crab seedlings. In order to be worthy of the word "Panjin crab", to avoid and correct some hard-won reputation of "Panjin crab", to avoid unnecessary losses for Panjin crab farmers and to improve the overall income in autumn, combined with the years of breeding experience of parents and neighbors, I made a close-up of this article.

The density of the captive crab in Panjin is closely related to the type of water body, natural or artificial bait, annual accumulated temperature, etc., and it cannot be artificially too thin or too dense-too thin will waste water resources, reduce the unit output and make the income unsatisfactory; If the density is too high, it will easily lead to the crab fighting for food and water space, and at the same time, the excrement of the crab will increase, resulting in insufficient dissolved oxygen in the water and water pollution, which will inhibit the growth of the crab. In a word, the stocking of detained crabs must follow the ecological criteria of related growth environment, the biological criteria of river crabs and the criteria of market economy. I will make a detailed analysis and explanation on the density of captive Eriocheir sinensis according to different water bodies and other conditions. Panjin Erli Crab Breeding Base: 0427-7787597. 1. Lake Reservoir Putting Panjin Crab Breeding in Lake Reservoir means releasing one-year-old crab seedlings in spring or before freezing in last winter, so that the crab seedlings can grow and fatten for 5-6 months, and the crabs will be harvested and listed in autumn of that year. It is suitable for the development and utilization of various large, medium and small lakes and reservoirs. Crab breeding in lakes and reservoirs is to add crab populations to original aquatic organisms such as fish, mollusks and aquatic plants, so as to achieve the expected specifications and output of adult crabs. There must be interspecific relationships between the released Eriocheir sinensis and the original aquatic organisms, such as competition and inhibition, predation and prey, and * * * health and * * * benefit. As a farmer, it is faced with how to deal with all kinds of relationships within and between species. Aquatic plants and zoobenthos are both indispensable biological species in Panjin crab recipes, and aquatic plants are also hidden places for crabs to inhabit. Grass carp is a fish that mainly feeds on aquatic plants, while other carnivorous fish such as carp, crucian carp, catfish and dogfish have strong ability to eat benthos, so river crabs, grass carp and carp are the competitors in food. The result of the competition is that the grass carp, which has a large individual, a large appetite and a relatively anxious personality, is dominant, while the Panjin river crab with high economic value is at a disadvantage in the competition and has a competitive relationship with other fish, which is the competition and suppression of interspecific relations. At the same time, there is also competition within the species of river crabs, with high stocking density and great competition for food, and there will be the phenomenon of killing each other. Protect the biological resources of lakes and reservoirs and take the road of sustainable development. Aquatic plants are the main components of aquatic organisms in grass-type lakes, and they play an important role in crab-raising lakes, which is beneficial to the life activities of river crabs, such as foraging, hidden shelling and growth. Some small fish that produce sticky eggs stick their eggs to the leaves of aquatic plants, which can also be used as bait for river crabs. All kinds of aquatic plants increase dissolved oxygen in water through photosynthesis, and precipitate inorganic substances and organic substances such as calcium and phosphorus in free state in leaves. When the river crab eats these aquatic plants, it actually ingests inorganic salts necessary for growth and development. Proper release of detained crabs is also a virtuous circle to protect aquatic resources, avoid destructive utilization of resources and realize sustainable breeding of river crabs. ? According to relevant data, the Yellow River starts from Heihe River in Heilongjiang Province in the north east to Kashgar in Xinjiang. According to the number of aquatic animals in lakes and reservoirs, 300 captive crabs with a size of 60-120/kg are released at one time from April to May every year or before the last year freezes. Autumn replenishment specifications can reach about 2 Liang. At the same time, it is necessary to stop raising crabs every three years1-2 years, so as to restore the ecological environment of lakes and reservoirs in time. This is what we often say that a piece of raw water can produce good crabs for three years. Because some lakes and reservoirs have deep water bodies and low temperatures, some river crabs were not caught that year, and they will grow out of their shells the next year. In autumn, adult crabs with large specifications appear, and some even reach 400 grams. Therefore, if it is not your own water body, it is best to contract the land for breeding river crabs for not less than three years! Second, shallow water bodies such as ponds and swamps?

Liaohe River Basin, Yellow River Basin, Heilongjiang River Basin, Tarim River Basin, there are many sufficient conditions for the growth of Panjin river crabs in large and small ponds, swamps and saline-alkali streams where water flows. Without artificial feeding, Panjin Eriocheir sinensis, which is cultivated extensively, can reach 2 Liang in autumn with reasonable density, and the big one can even reach 3-4 Liang. Crab culture in shallow water bodies such as ponds and marshes is generally carried out after a little modification of fish ponds or reeds and marshes. It is required that the water quality is fresh, there is no pollution source nearby, the water quantity is abundant, the water level in different time and space is 0.3-2 meters, the total area is large (generally not less than 10 mu), and the bottom quality is black loam > Clay >: Sandy soil From March to May, after thorough pond cleaning, disinfection and water discharge, the crab fry should be put in when the water temperature is stable above 4-5. According to many years' experience in stocking captive crabs in different parts of China, the most suitable size of captive crabs is 60 ~120, that is, each crab weighs 5 ~ 8 grams, and very few of them are used in cold areas in northern Heilongjiang. If the size is too large, it is easy to reach sexual maturity after shelling once, while if it is too small, it will affect the survival rate and adult crab specifications. Most shallow water areas, such as ponds and swamps, are extensively cultivated, so it is strongly recommended that the density should not be too high, otherwise they will kill each other because of the lack of oxygen nutrients in water space, or the disease will increase and die because of the deterioration of water quality, or the harvest specifications will be too small and the benefits will be low because of the competition in space, resulting in economic losses and loss of confidence in cultivation. So-called "happy cultivation, disappointing harvest". Put 400-600 crabs per mu with a size of 40-60, with ∑8 kg ~12 kg, which can reach 2.5 crabs in autumn; The size is 60 ~150, 500 ~ 800 per mu, ∑4 kg ~13 kg, and 2-2.5 ounces of river crabs can be collected in autumn. Panjin Erli River Crab Breeding Base: 0427-7787597

In 2003, Professor Yu Yongqing from Panshan County Crab Breeding Technology Research Institute (a special expert of Erli Crab Breeding Demonstration Base) instructed Baiqiangzi Town of Panshan to adopt the "big ridge and two rows" rice planting mode to conduct large-scale adult crab breeding experiments in rice fields. The rice planting mode of "big ridge and double rows" not only solved the problem of insufficient light in the late growth of river crabs, but also expanded the activity space of river crabs. Moreover, because of the good ventilation and light transmission of "big ridge and double rows", the rice yield increased instead of decreased. At the time of harvest, the average size of adult crabs was 82g, and the average yield per mu was 26kg, which achieved the good benefit of average income per mu in 490 yuan (excluding rice increasing in 90 yuan). In 2004, this model was popularized in the local area. In autumn, the average size of adult crabs was 84 grams, the average yield per mu was 26.5 kilograms, and the average benefit per mu was 498 yuan, which was a good harvest with an increase of 246 yuan compared with the conventional rice planting model. To sum up the technical points of this crab farming model, it is: (1) rice planting model. "Double rows of big ridges" means changing the conventional 9-inch * one ridge to 6-inch one ridge 12-inch one ridge at intervals. (2) Field engineering. Temporary pond10m x 25m-28m x1.0m; Ring ditch1.2m x 0.6m x 0.4m. (3) stocking density. There are about 500 crabs per mu 140- 180/kg. (4) stocking time. In late April, the overwintering Eriocheir sinensis was put into the temporary breeding pond, and it was put into the field in time after transplanting. (5) Daily management. Panjin Erli River Crab Breeding Base: 0427-7787597? ① Water quality control: apply 40 mg/L of quicklime before molting every time, and sprinkle 5-8 mg/L of photosynthetic biological liquid after 48 hours; Deepen the water layer as much as possible when rice growth permits. ? ② Bait feeding: concentrate (high-quality compound feed, miscellaneous fish and shrimp, etc.) is mainly fed after seedling release, green roughage (barley germination, water weeds, etc.) is mainly fed from mid-July to mid-August, and concentrate is mainly fed after mid-August, together with new corn and new sorghum rice. The feeding amount shall be subject to a slight surplus observed after feeding 1 hour. ? ③ Scientific fertilization: It is best to apply fertilizer at one time (accounting for more than 90% of the total amount of fertilizer) before harrowing in crab paddy fields, otherwise, apply less frequently, and the amount of fertilizer applied each time should not exceed 3kg/mu. ? ④ Disease prevention: Before releasing the detained crabs, the temporary breeding pond was disinfected with quicklime (70kg/mu) with water10cm, and 20kg of quicklime was sprinkled on each mu in the field for supplementing calcium, and dibromohydantoin was used the next day (mainly used as a disinfectant and algaecide, which can effectively kill various bacteria, fungi, viruses, algae, hepatitis virus, Escherichia coli, Staphylococcus aureus, gonorrhea and so on). Disinfection and sterilization of industrial water, tap water, domestic sewage and swimming pool. Disinfect the detained crabs with 3% saline or10mg/l potassium permanganate solution before entering the temporary culture pond. ? Analysis, although the specifications of this model are small, but the benefit of increasing mu is obvious, it is worth popularizing. If the technical management is further strengthened, I believe the specifications will be improved.