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The structure and device of the cage.
Apr 07, 2018

The structure and device of the net box are many, the actual use should not escape the fish, durable, the province is economical, convenient for the water exchange, the management convenient and so on the principle.

(1) the structure of the cage.

1. The cages constitute

It consists of box, frame, float, sink and fixed facilities.

(1) box: the mesh is stitched together according to a certain size. The most common application is polyethylene mesh, which has the advantages of high strength, corrosion resistance, low temperature resistance and low price. There are four kinds of processing technology of the mesh: the polyethylene - polyethylene wire mesh. The advantages are good scalability and durability. The disadvantage is that there are nodules, easy to graze the fish body, the material is much, and the filtration water is poor; It is not extended without nodules. The process is fast, economical and cheap, but the transverse tension is poor and fragile. There are no nodular meshes. Its tensile strength, softness and light weight are less than 3/4 lower than that of nodules. It is a polyethylene warp knitting mesh. No knot smooth, no harm to fish body, the mesh is shaped not to go out of shape, the box body is soft, easy to sew, not easy to open the hole to escape fish, the cost is low.

(2) frame: it is a bracket used for hanging box body. It is usually composed of nanzhu, wood, steel pipe, plastic pipe and other materials. The box body is fixed on the frame, which can keep the box open and forming.

(3) float: the device that makes the net box float on water. A float made of foamed plastic and hard blow molding, or a float on a frame with a glass ball and a metal drum. Bamboo, wooden frame in support box body, also play the role of float.

(4) sink: a device that causes the bottom of the net box to sink into the water. It is usually made of porcelain sink or stone, cement block, etc. Available diameter of 2-2. 5 centimeters of steel tube, can open bottom net, also can be used as sink.

In addition, the location of the network box shall be fixed with the iron anchor, or the fixed net box shall be supported by cement piles and bamboo piles.

2. Box shape

Rectangular, square, cylindrical, octagonal, etc. At present, the rectangle is often used in production, the second is square, because its operation is convenient, the water area is large, the production is convenient.

3. Box size

The smallest area covers an area of 1 square metre, usually 1-15 square metre cages small cages, caged area in 15 to 60 square meters for medium to large area in the 60-100 square meters, with 500-600 square meters. Generally speaking, the area of the net box should not be too big, too big operation inconvenient, the wind resistance is bad. But the output of the small net box is high, but the cost is high. Currently, most of the boxes are 10-30 square meters, namely 7 x 4 meters, 5 x 3 meters, 3 x 3 meters, 3 x 4 meters and so on.

4. Height of the cages

The height of the cage is determined by the depth of water and the vertical distribution of plankton. It is currently 1.5 to 2.5 meters high. The water depth can also be used in the height of 2-4 m. However, the minimum distance between the bottom of the net box and the bottom is at least 0.5 meters, so that the bottom waste discharge the net box.

5. The mesh size

The size of the mesh should be determined according to the breeding object, so as to save the material as far as possible, and the maximum exchange rate of the water body is the principle. The mesh is too small, which not only increases the cost of the net box, but also affects the exchange of water flow. The mesh is too large, and there is the phenomenon of runaway fish. Usually raise 4 cm summer flower fish species, use mesh 1. 1 centimeter net box; Raise 11-13 cm of a fish species, use mesh 2. 5-3 cm net box; Form the net box of fish, use 3- 5cm mesh net box. In order to facilitate the exchange of water and reduce the number of washing times, it is better to change the net box with larger net.

(2) the device of the network box.

1. The type of cage device.

According to the water condition, the feeding object and the type of the net box, there are three methods in China.

(1) floating net box.

Casing stitching around such mesh with bamboo into the framework, such as mesh around the outline tied on sinker and rope with moored on both ends of the frame, flowing with mesh sealed, frame attached to float, float on the surface of the water.

The floating network box structure is simple, the material is less than the province, the wind resistance is stronger, it can fluctuate freely with the water level, wind direction and water flow. Generally set in the open water, the water level is unstable, the ship has less water surface.

The floating net box has a single box floating type and multi - box floating type. A single box floating type is a single box set with a single anchor or double anchor. Its water exchange is good, convenient to turn the box and clean the net box, but the wind resistance is poor. Multi - box floating type is 3-5 net box, series is a column, the two ends are fixed with anchor, the distance between each net box should be greater than 50 meters. This method occupies little water surface, the management is relatively concentrated, suitable for large area development, but the production effect is inferior to single box floating type.

(2) fixed net box.

Ordinary for exposure to the cages, the pile and rail link into the framework, the cages hanging on the frame, such don't float, forward pile up and down between up and down the corners of a hoop or pulley, easy to adjust the cages lift and washing box, fishing, etc. The net is exposed to the surface of the water 0.7 to 1 meter, the net body underwater 1.5-2.5 meters. Normally, the box body cannot rise or fall with the water level. This method is only applicable to shallow water lake peaceful prototype reservoir with small change of water level. Advantage is low cost, convenient operation, easy to govern, was strong, the disadvantage is that cannot move, difficult to set in deep water area, and fish habitats within the cages with the water level change and change often, if you don't pay attention to timely adjust will affect the breeding effect.

(3) sunken net box.

The entire net box sank at an underwater predetermined depth. The net body is not affected by the change of water level, and the attachment of the mesh is small, which is affected by the wind and waves and the water flow, which is suitable for the use of the seawater cage fish and the place where the wind and waves are large. Northern China is often used as winter fish in winter. The disadvantage is that the operation is inconvenient, the fish growth rate and the production level is low.

2. The way and density of the grid arrangement.

The method of network box arrangement should consider to ensure that each network box can carry out good water exchange, management is convenient for the principle, the net box should be as sparse as possible to open the finished product glyphs arrangement.

The density of the cage shall be determined according to the water quality conditions and management conditions. The net box of silver carp and bigherd fish, the net box can account for 1% of the high water surface and 0.5% of the water quality. The fish that breed to eat sex, want to depend on the current situation of water of the water itself, water quality, dissolve oxygen content to decide. If the water flow is good, the fat degree is moderate, the dissolved oxygen is high can set the net box more, conversely less.

3. The water layer of the cage setting.

The depth of the box set, generally no more than 3 m, because of the distribution of plankton, accounting for 58.7% of 2 meters of water, and 2-4.2 m (41.3%), especially small water transparency, most abundant phytoplankton, zooplankton and number 1 meters water depth layer is less than 1-2 meters of water, especially in 2-3 meters density is the largest. Therefore, the net box should be set in the shallow water layer, but the bottom of the net box should be more than 0.5m above the bottom. In the water of the water of thin water, or the net box that raise bigher fish, can be set in a deeper water layer as appropriate, but unfavorable too deep.

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