Scylla serrata, commonly known as blue crab, is an animal of the genus Crustacea, Swissidae, and Scylla. Its fast growth, strong adaptability, delicious meat, and rich nutrition make it an important economic crab in China.
Blue crabs are abundant in the coastal areas of Zhejiang, Fujian, Taiwan, Guangdong, Guangxi, and Hainan in the south of the Yangtze River in China. The largest individuals in the natural sea area can reach more than 1 kg. China's artificial breeding of green crab has a long history, especially in recent years, with the rapid development of marine aquaculture, the aquaculture area continues to expand, green crab has become one of the main species of marine aquaculture.
First, culture methods
Due to the specific ecological habits of the blue crabs, and various local conditions of sea conditions, crab seedlings, feed supply, and the management level of breeding techniques, as well as different ways of marketing crabs, there are various types of crab culture. There are pond-type, fence-type, corrugated-type, wooden-box-type, and fish-e-type cultures. Divided by the mode of operation, extensive, semi-intensive, intensive. In terms of stocking methods, there are monoculture and polyculture. Polyculture can be divided into polyculture of shrimps and crabs, polyculture of fishes and crabs, polyculture of crabs and shellfish, polyculture of fish, shrimps and crabs, and polyculture of blue crabs and various aquatic economic organisms. . Irrespective of the type of aquaculture adopted, the farming methods suitable for their own characteristics should be selected according to local characteristics.
Second, the conditions of the aquaculture pond and preparation before stocking
1, the conditions of the aquaculture pond
Crab ponds should be built in calm seas, with fresh water injections, unpolluted inner bays, or sand mudflats with a certain slope below the mid-tide line. The depth of the crab ponds should be maintained at 0.8-1m when dry tides are needed. The area is generally 2-5 acres. The area is too large, it is difficult to drain water, and it requires a lot of manpower and material resources. The bottom of the pond is square or pot-shaped. The shallower water should be digging the ring ditch and cross ditch to facilitate the activities of blue crabs, creating a cool summer and warm winter environment to facilitate the growth of blue crabs. The sediment quality should be better with sand and mud. The pool water requires a pH of 7.5-8.5, and a ratio of 1.00-1.020 (the best 1.010-1.015) of seawater. The test shows that the survival rate, unit yield, and economic benefit of the crab are reduced when the specific gravity is less than 1.002. Maintaining a specific gravity of 1.022 for more than one month results in the death of a large number of blue crabs. The pond embankment is made up of three-segment soil or stones and a cement-free upright bank. The earth embankment can also be, but the pool should be blocked or bamboo foil inserted around to prevent the crab from escaping. There is also an intake and drainage gate for the crab pool, which will facilitate the exchange and convection of the pool water.
2. Preparation before restocking
Before stocking, ponds should be cleaned and disinfected. The Laotang shall be fully cleared, including clearing silt in the trenches, draining ponds, repairing the surrounding anti-escape facilities, and collapsing embankments. Ten days before stocking, 120 kg of quicklime or 15 kg of bleaching powder was used as a suspension for the whole pond to be splashed to kill the enemy inside the pond.
Third, the selection and stocking of crab seedlings
1, the source of crab seedlings
There are two types of crab seedlings: one is the big eye larvae obtained by artificially growing seedlings, which is cultivated into suitable young crabs in the middle, and the second is crabs or young crabs that are caught in natural sea areas.
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