The New Technology of High Yield and Efficient Breeding of Portunus trituberculatus
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I. Basic conditions (take 3# as an example)
1. Pond conditions Ponds are east to west, sandy bottom, and have good drainage conditions. The maximum depth is 1.7 meters and the area is 150 acres. In the late autumn and early winter, after the breeding season is over, the remaining water in the pond is pumped out and dredged and exposed. In the early stage of dredging, the mud pump is used to pump the net, and the bulldozer is used to level the earth at the later stage. The ring ditch is left around the pool. The ditch is 2 to 4 meters wide and the beach surface is 30 to 40 centimeters low. The drainage system is well maintained. The original two ponds, 75 acres of single ponds, were used mechanically to cut off the east and west sides of the middle dam, leaving a groove 3 to 4 meters wide and 1.6 to 2 meters deep, artificially bringing the pond water into dynamic operation. It is closer to the native state of the crab and easier to divide into ponds.
2. Water disinfection fertilizer (1) water. 20 to 30 days before planting seedlings to receive water, the first phase of water 40 to 60 cm, generally 30 to 40 cm beach surface, easy to natural warming, ring ditch 70 to 80 cm, will help spring cold seedlings.
(2) Disinfection. Combine water to disinfect, culture pond advanced water 20 to 30 centimeters, store surface water above 5 centimeters namely line medicine to disinfect, in order to improve sediment and kill pests, generally Mushi lime 100 to 150 kilograms, or high-quality bleach 8 ~12 kg. Disinfection, select the sunny weather from 9 to 10 o'clock in the morning, the use of water slurry, sprinkled throughout the pool, thick silt, corners, ring ditch more sprinkle.
(3) Fertilization. At present, more methods are used to use fermented chicken manure as a base fertilizer, supplemented with inorganic fertilizer in the middle and later stages. Chicken manure fermentation method is to dig pits on the sunny side or corner of the pool, and the size is not limited. The chicken manure and water are placed in the plastic film cylinder at a ratio of 1: (2 to 2.5) and placed in the pit. Fermentation in the sun for 7 to 10 days, the slurry poured into, and then add water fermentation, repeated 2 or 3 times, the manure was all sprinkled into the pool, the pit filled. Inorganic fertilizers mainly include urea, ammonium nitrate, compound fertilizer, and superphosphate. The production practice shows that the ratio of nitrogen to phosphorus of 370:7 is more suitable for local fertilization.
Second, put the seedlings
1. The time for releasing the seedlings is within 10 to 20 days of May. It is better to select the young crabs (commonly known as “202†seedlings) of the second-stage mature crabs with high quality, robustness, strong vitality, and no sickness.
2. Seed transportation of seedlings in the near field (within 1 to 2 hours) can choose water transport method, that is, film bag plus water grass or mesh method, per bag seedling 10,000 to 20,000, water 1/3, gas 2/3, inflatable transport. Long-distance transport (10 to 12 hours) is commonly used method is to use rice hull mixed dry loading method of crabs, the young crabs will be drained after the water, into the prior low temperature (plus ice, about 10 °C) bubble through the drain Dry new rice hulls are then loaded into the seed bag in a dry and dry way. Generally, the distance is 0.5 to 0.75 kilograms per bag depending on the distance of the road. The transport rate is 10 to 12 hours, and the survival rate is generally above 97%.
3. After the seedlings are planted and reach the pond, clean and seawater is sprayed on the dry transported crab seedlings with a small sprayer. The seedlings are put into the pond after 5 to 15 minutes. For short-distance water-feeding seedlings, the seedling bags are first placed in the pool water to adjust the temperature, and the bags are opened 5 to 10 minutes. The pond water is mixed for 2 to 3 times, each time for 3 to 5 minutes, and then the crabs are poured into the pool. Putting the seedlings in position should be placed in the depth of 30 to 40 cm in the pool, leaving dozens of meters away from the pool, and the second is to choose the upper wind to put the seedlings in order to avoid the weak seedlings being blown to the shore to kill them by the wind and waves. The third is to put the seedlings in multiple positions and not to make the seedlings. The partial concentration causes disability.
4. It is advisable to put the seedling density at 3500-4000 per acre.
5. In the second to third days after the larvae are released, the young crabs are transferred to the third stage and should be fed on the second day. In the case that the basic food organisms are abundant, the feeding may be delayed as the case may be, so the water temperature in the pool Low, crabs less palatable feed, should be added live Artemia or frozen Artemia is better, or after subtraction crushed shrimp and shrimp species. After the crabs enter the five young crabs, they should increase the number of low-value shellfish such as Lancome.
Third, the division of male and female culture and sub-pool cultivation This link is to improve production, increase production and increase the effective measures and key points, are described below.
1. In mid-June of June, 20 to 30 days after the crabs enter the pool, the juvenile grows to a width of 3 to 3.5 cm or more. When the human eye can distinguish between male and female, the male and female are artificially separated and cultured, usually at night. When the activities began and the food was eaten, the organization concentrated its manpower to use “grabbing the net†(one end is shaped like a bucket and tied with a long rod) to carry out operations along the pool weeks and concentrate the harvested young crabs. Small ponds with a size of 20 mu or less can be set up to store large-scale open cages, separated by males and females, and cultured separately. Larger ponds generally need to be seeded for 3 to 5 days and can capture more than 95% of juvenile crabs. Specialized small ponds (2 to 6 mu in size) are required to be stored in a centralized manner. The operation should try to avoid the peaks of the molting, and Strengthen feeding to reduce self-harm. After the young crabs are removed, male and female labor will be carried out and cultured in separate ponds.
2. Sub-pool culture In order to facilitate later mating and maturing of female crabs, it is best to pierce the middle dams of two adjacent breeding ponds to form a tandem pond with the same body of water. The net divides it so that it will be one day, then the Mid-Autumn meets and mates. There are slight differences in the method of male and female pooling. The ponds for male crabs are cultured so that they will be listed on the pond early in the morning. The breeding should be started immediately after the start of breeding, and the fertility should be rapidly increased. The first batch of ponds is usually around the 15th of the lunar calendar. Female crabs are listed about one month earlier than the Mid-Autumn Festival. At this time, there are fewer marketed crabs and the price is higher than that of the late male crabs. Two-thirds of the male crabs are released for marketing and 1/3 of them are used for pond fattening. The cultured female crabs generally have a little control over the pre-feeding, so as to avoid the premature deterioration of the pool bottom and affect the female crab phase and price. After the female crabs have been sold out, the net is removed in time so that the males and females will be polygamous at a ratio of 1:3. Because the female crabs are only mated after they have been mated, the plumpness of the female crabs becomes more plump. Fertilizer level. After the August 15th of the lunar calendar, you can catch the fish in the shallow water of the pond or catch it artificially at night to collect the females for the second time. The females can also sell their mothers. Female crabs can also be sold according to the needs of the market. The net has been withdrawn. The space for swimming crabs to swim along the pool has increased. This has solved the problem of excessive pond load in the later period. Crabs in large-scale activities have thick limbs and bright white abdomen, which are closer to natural crabs and have a price advantage.
Fourth, change the water and feeding
1. The high-density culture under the artificial conditions of water shuttle crabs is prone to “bad water†phenomenon. In the middle and later stages, the water should be replaced in time and vomiting should be completed in order to ensure the crab growth and molting. Conditions allow, with aerators better. In general, aquaculture water should be replaced once every 5 days in the later period of culture.
2. Feeding correctly estimates the number of pools at each stage of the crab and timely checks the amount of remaining bait on the previous day to determine the amount of feeding the next day, regardless of male or female, in line with the “early marginally owed, the mid-term flat, and the later slightly marginalâ€. The principle is to adjust and determine the frequency and quantity of feeding, generally once a day in the early period and 2 or 3 times in the later period. The night feeding amount accounts for 70% of the day. The species of bait crabs cultured in large areas are generally Artemia, Lancome, and miscellaneous fish, and some of them are artificially fed with baits.
V. Results
From 2003 to 2004, the new method of breeding was different from the traditional method. The yield per mu in most ponds was between 65 and 75 kg. The situation in the 3# pool in 2004 was: an area of ​​150 mu. The seedlings were released on May 10 and the number of seedlings was 3500. Only/mu, June 6th seedling, Chinese lunar calendar sold out on July 15th, individual average weight 110~120g, unit price 35 yuan/kg, female lunar sold off on August 15th, lunar average weight 250 About grams, unit price 76 yuan / kg. A total of 3.2 tons of Artemia, 27 tons of Lanzhou, 140 tons of miscellaneous fish, and 8564 kg of communist crabs were produced. The output value was more than 680,000 yuan and the profit was more than 280,000 yuan.
Author: Shandong Weifang Fisheries Research Institute
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