Portunustrituberculus is a famous large-scale seafood crab and it has high economic value. The crab spreads over the coast of China, and the output of the East China Sea and the Yellow Sea and Bohai Sea is relatively large. In recent years, due to the changes in the structure of marine fishery resources, the natural resources of swimming crabs have declined rapidly, the value of commodities has doubled, and artificial breeding has risen rapidly. From 1994 to 1998, we began experimentation and demonstration in shrimp ponds in Yangshu District, Fuding City, Fujian Province. In 1998, 100 mu demonstrations were carried out. A total of 6,350 kilograms of crabs (including 2,100 kilograms of male crabs and 4,250 kilograms of female crabs) were harvested with an output value of 466,600 yuan. Profits and taxes were 316,500 yuan, an average increase of 63.5 kg, and an input-output ratio of 1:3.1. Significant social and economic benefits were achieved. The current situation of aquaculture is summarized as follows: I. Technology and methods (I) Site selection The breeding site is to be selected from two 50-acre ponds in Yangshuo area where there is no pollution, clear water quality, and free of wind and waves. The specific gravity of seawater is between 1.010-1.020. The average water depth is 1.5M, the depth is more than 2 meters, the transparency is 40-60cm, the sediment is sandy, the chemical oxygen demand is 4.2g/l, the ammonia nitrogen content is less than 0.3g/l, and the H2S content is 0.008g/l. (B) Cultivation 1, pond transformation: the bottom of the pool plowing 20cm, exposure, at a distance of 2 meters away from the dike, dug a 1 meter deep, 2 meters wide ring ditch, check the gate, blocking the network is damaged, found that the problem is repaired in time . 2. Qingchi: One month prior to planting, water 30cm, add lime 50ppm, soak 3 days, rinse. 3. Biological bait culture: 10 days before planting, water 60cm, N fertilizer (urea) 20ppm, when the pool water is yellowish green, begin to live low-value shellfish 80 Tam, evenly sowing into the bottom of the pool, as a living body Spare bait. 4. Investment seedlings: (1) Seed origin and transportation: Farmed seedlings are harvested from natural sea areas. At the beginning of April of the lunar calendar, the portuguese crab seedlings begin to appear in the sea area. Generally, the young crab shells start to be caught when the size of the small nails is small. The carapace length is about 0.6. -0.7cm of crab seed per 3000 grams 3000-4000 only. The transportation method is generally to add proper amount of sawdust onshore transportation using a special box for crabs. As the shuttle crab seedlings are more prone to dehydration, the shorter the transportation time, the better. It should not exceed 24 hours. (2) Investment seedlings: The seedlings are to be cast in early April in the lunar calendar. The seedling volume will be determined according to the crab size of the sea area. Generally, the length of the back carapace will be 0.6-0.7cm and the seedling volume will be 250g per mu (about 1500-2000 pieces). ), Crab seedlings in more than 50 grams, put 25 kilograms per mu (500), put the seedlings will be dead, injured, diseased seedlings removed, seedlings into temporary holding pool holdings, seedlings directly stocked. 5, aquaculture management: (1) feeding management: crab foods mainly animal feed, fresh, free from contamination, low-value small shellfish, small trash fish shrimp is a favorite food bait, feeding the amount and breeding of swimming crab Environmental conditions such as size, quantity, and temperature are closely related. Usually every day sooner or later each time, when the amount of seedlings, according to the weight of 100%, as the weight of the crab increased gradually reduced feeding, after the weight of 50 grams of crab, the amount of feeding control in the weight of about 10%, most feed bait In the beachside bait station and its vicinity, a small number of scattered shots are generally measured in terms of feeding time after feeding for 3 hours or more, and given timely adjustments. When the weather is boring or heavy rain, the food should be less or no investment. (2) Water quality management: Generally, change the water once every 3-5 days, change the water volume from 30% to 50%, ensure the water quality is clear, and keep the environment stable. In case of continuous heavy rain, try to put the upper pool water. Evacuate slowly and inject fresh seawater with high salinity to keep the specific gravity of seawater above 1.015. When entering and leaving the drainage, observe carefully. If you encounter red tide water, exchange of water is prohibited. (3) Disease prevention and control: Adhere to the principle of "prevention first, prevention and control combined, and comprehensive management", maintain good water quality, feed high-quality fresh bait, and regularly put antibiotics during high temperatures. (4) Other management: Regular patrols, anti-theft and anti-theft work. 6. Harvest: The lunar calendar began harvesting in November. Take a drain to harvest, drain the water, catch the net, separate the male and female crabs, and bind the big claws with rubber bands. Male crabs are sold (If the crabs do not catch them in time, they will begin to die after mating), and the female crabs will be put into the temporary holding pool to raise the nourishing cream. They will be caught in the middle of the lunar calendar in mid-December, and should be put into the market during the cream season. Fish, etc.) to enhance physical fitness and increase fullness. Second, the results and discussion 1, growth, life habits. The three-ported Crab is a benthic crustacean that inhabits the nearshore and shallow seas. It is nocturnal, good swimming, lively, greedy, and easy to kill each other. The growth of the crab does not have continuity, and it can only grow through the oyster shell. The clam shell is the most vulnerable during crab growth and is vulnerable to attack. Generally about 0.6-0.7cm in the length of the back crab is found in the crab shells after about 10 times, 6 times in the oyster shell in April and May, and once in the other shell in the moon. The shell grows until the end of the lunar month in mid-September. Crabs began to mate after the last oyster shell, and the gonads began to mature. Male crabs began to die after mating. Therefore, the proportion of female crabs was larger than that of male crabs at the time of harvest. 2, water temperature, water quality, climate and feeding relations. At dawn or dusk, the crabs have the most intense feeding activity. When the water temperature is between 25°C and 30°C, the crab has the most appetite. When the water temperature is lower than 15°C or exceeds 35°C, the food intake decreases. When the water temperature drops below 10°C, the food intake stops and the winter begins. When the water quality is not good and the weather is boring, the amount of feed should be controlled so as not to damage the water. 3. Effects of different substrate, salinity, and water depth on body color of the crab. With higher salinity (1.015 or more), sandy bottom (or sandy bottom), and an average depth of 1.5m above the culture area, finished swimming crabs are beautiful in appearance and have appendages clean. They are closer to the natural swimming crab and have higher commodity value. The finished crabs with low salinity (below 1.010), muddy bottom, and an average of about 1m in the culture area had poor body color, appendages were dirty, and the abdomen was yellow, and the commodity value was low. 4. The effects of different feeding amount and feeding type on the survival rate of crab crab and the fullness of female crab red paste. Swallow Crabs are ferocious, lack of food, causing fratricide, affecting the survival rate, especially when large quantities of clam shells, to cast enough food, but not too much, causing water quality corruption. After the start of mating of the crab, it is necessary to start feeding high-quality foods rich in protein, and the best type of food such as A. sinensis is best, and more than 95% of female crabs are full of body fat.
Rock Fall Mesh,Fresh Goji Berries,8010Mm Gabion Hexagonal Mesh
Triangle Bending Fence ,Related Products Co., Ltd. , http://www.chsteelmesh.com