In recent years, with the continuous expansion of the scale of freshwater aquaculture and the continuous increase of aquaculture species, the fishing methods of cultured fish have attracted more and more attention. Traditional fishing methods and fishing tools have high labor intensity and low efficiency, which can no longer meet the fishing demand of large-scale fish ponds. Therefore, how to use the new technology to develop the aquaculture starting and catching machinery is a problem to be solved. In the production process, the traditional fishing methods and fishing tools are improved by combining the original aquaculture technology with civil engineering, physical science, computer, etc., so as to meet the current demand of pond aquaculture.
Mechanical fishing with net lifting
1. Working principle
Net lifting fishing is to use the trapping light or feeding machine to feed and attract the fish to enter the trapping area, and to use the net lifting which has sunk into the water bottom in advance to quickly lift and trap the fish in the net, so as to achieve the purpose of fishing. Net lifting is divided into mechanical net lifting and inflatable net lifting.
2. Basic composition and usage
Mechanical lifting net mainly includes: electric hoist, pulley, fishing net, fixed rod, general control pulley, general control rod and lifting net rope, etc. The type of pulley includes moving pulley and static pulley, which are located at the top of four fixed rods and connected with the trawl rope. The trawl rope is collected to the master control pulley, which controls the lifting of all ropes and fishing nets. The master control pulley is fixed on the master control rod on the shore and powered by the electric gourd.
Use method of mechanical lifting net: insert four fixed rods around the baiting platform, each rod has a sliding device at the top, the fixed rod is connected with the net in the middle, and the rope controls the lifting of the net. When fishing is needed, put the net into the pond around the feeding platform before fishing, and then turn on the feeder. When the fish gather in the feeding platform, start the electric hoist to quickly close the control rope, and the net will be raised from the bottom of the pool to form a net, so as to catch the fish on the feeding platform.
The inflatable net lifting device includes fishing net, inflatable tube, inflatable equipment, gas storage device, etc. The inflatable lifting net has more flexibility in use and operation, fast lifting speed and movable fishing. If ten baiting areas are set up in a reservoir of one thousand mu, each baiting area is about 100 mu. According to the habits of fish and the principle of “three fixations” of scientific fish feeding, after a period of feeding, the fish will concentrate at the point of each baiting area. If you want to catch the fish in that baiting area, place the mechanical pneumatic fishing net at the bottom of the baiting area, continue feeding for several days, and then start feeding Stop feeding in front of the net for one day. When starting the net, open the air pump valve first, and the inflation pipe will be filled with gas to float up quickly. It can float up to the water surface in about 2-6 seconds, forming a cage. Because the fish will rush to eat, the net will be lifted and then the net will be started about 10 minutes after baiting. For the wild fish caught in large reservoirs and rivers, if the light is used to trap silver carp, silver carp, red pomfret, white pomfret, bream, blunthead bream, perch and swordfish, the effect is more than 95%.
Specific method: when the pneumatic fishing net sinks, several 100W waterproof lamps are installed under the water and on the water surface of the middle water area of the net, which can illuminate the water area of the net at night. Because the zooplankton, phytoplankton and benthos in the water area have strong light driving property, and the purple light line can penetrate into the deeper water layer, which can make the zooplankton, phytoplankton and bottom in the surrounding water area bright The benthos are attracted to a lighted domain. Fish are most sensitive to the purple light in the spectrum, and there are abundant natural baits in this bright water area, so it is labor-saving, time-saving and money-saving to catch these aquatic products. It is suitable for large area fishing in deep sea, shallow sea, rivers, lakes, reservoirs, ponds and ditches. The unique design can overcome many shortcomings and difficulties. The fishing area is large, the fishing effect is good, and the fish body is not damaged. It can be fished at will and transported at any time in cooperation with the fish cage.
Mechanical net lifting can’t be moved to catch, the speed of net lifting is slow, and the degree of fish damage is general. Due to the influence of terrain and vegetation conditions, the reservoir has not found an ideal way to catch fish before. Through light induced fishing, the use of animal phototaxis to attract a large number of fish like predators to gather, and then attract the reservoir silver carp and Bighead Carp and small wild hybrid fish to gather and catch. Using light to lure fish and inflate net to catch fish can overcome the influence of the complex topography and vegetation of the reservoir. It is mainly used to catch silver carp and bighead carp in the reservoir and small wild fish in the reservoir. Because of its simple operation, low labor intensity and good fishing effect, it is widely used in the reservoir.
Pond mechanical trawling system
1. Working principle
The pond mechanized trawl system uses the power of the tractor to transmit to the working drum through the hydraulic system, and then drives the nets to pull (lift) the nets through the steel wire rope and the lifting rope, and then transmits to the live fish car through the lifting winch and the conveyor car.
2. Basic composition and usage
In the pond mechanized trawl system, the tractor head is used as the power source, and the equipment platform is connected with the tractor head. When trawling in the pond, the tractor will transport the platform to one end of the pond where the fish is caught, install the nets and operate the fishing. After fishing, the vehicle head is separated from the equipment platform and other transportation operations are carried out. Install the left traction winch, right traction winch, folding guide rail, conveyor, oil tank and operation handle on the equipment platform. Four vertical piles are installed in the four corners of the rectangular pond, and the steel wire ropes tensioned on both sides are used as the front and back guide ropes of the mesh on both sides of the trawl. The front and rear piles are composed of fixed piles and movable piles. The fixed piles are round steel pipes with an inner diameter of 114 mm and a length of about 1.2 m. The fixed pile is pressed into the soil by concrete or mechanical means, and the top of the pile protrudes about 100mm from the soil. The movable pile adopts a round steel pipe with an outer diameter of 108 mm, on which the pulley is welded, the eye plate is hung and the guide cable is used.
When trawling, the movable pile shall be inserted into the fixed pile steel pipe, and the net, pulley and guide cable shall be installed. The guide cable shall be tensioned through the tensioner, and the net shall be placed at the end of the pond. At the same time, the left and right hauling winches are used to pull the nets forward and gradually move them to the top of the pond. Gather the fish and lift them to the shore through the conveyor car. After trawling in the fishpond, the components on the pile shall be removed, the movable pile shall be removed, and the rain cover shall be covered on the top of the fixed pile circular pipe. The fish ponds are then replaced for similar trawling operations. The purpose of adopting the detachable movable pile is: after the movable pile is removed, the top of the fixed pile is only a small distance from the ground, which does not affect the passage of various vehicles on the aisle. When trawling is needed, the movable pile can be quickly inserted and fixed.
Arrangement of mechanical trawlers: when trawling, generally there are 2 people who step on the bottom line, 1 tractor operator and 2 people who pull the upper line, a total of 5 people. When the net is closed, generally 2 people step on the bottom of the net, 1-2 people lift the top left and right, and 2 people drag the bottom of the net, 5 people in total. When the fish is transported by lifting, generally 1-2 people, 1 person operates the hydraulic lifting system, 1 person carries the basket on the bank, 1 person weighs, about 5 people in total, so only 5 people are needed to complete the whole mechanical trawling process. Generally, 10-12 people are needed to complete the above tasks manually. It can be seen that the way of mechanical trawling is widely used. No matter nylon or polyethylene nets are used for trawling operation, as long as the net shape design is reasonable, the fishing rate of trawling can be equivalent to that of manual trawling, and the number of operators is half of the total manual trawling.
The fishing net towing device is used to guide the left and right classes of the fishing net to move in a straight line along both sides of the pond, and to open both sides of the fishing net. The guide cable is a 12mm diameter steel wire rope. Due to the force on the mesh when trawling, the two ends of the upper and lower classes will close to the inner side of the pond. If the guide cable is not pre tensioned, it will be dragged into the pond by the upper and lower classes together, so that the fish in the trawl will escape over the guide cable and upper class submerged in the water. Therefore, it is necessary to pre tension the guide cable to prevent it from being dragged into the water by both ends of the upper and lower classes.
Traditional trawls have the same mesh specifications. In order to prevent the mesh from floating in the water when dragging, metal chain or metal sinker counterweight is generally used for the mesh bottom. For small mesh mesh mesh mesh with mesh size of 10-20 mm, because the mesh close to the bottom of the pond is small, the bottom of the pond is easy to be carried in the net when trawling, which increases the traction resistance of the winch. In serious cases, the mesh close to the bottom of the pond will be embedded in the bottom of the pond and cannot be dragged. After improvement, the nine row mesh near the bottom mesh is magnified by two times, which is conducive to the passage of the pond bottom mud from the large mesh when trawling, and reduces the drag of trawling; at the same time, 480 rubber rings with length of 60mm, outer diameter of 20mm and inner diameter of 11mm are evenly distributed on the 70m length of the bottom mesh to replace the original metal sinker or chain, so as to make the bottom mesh more evenly stressed and the traction greatly reduced. The mesh material is polyethylene diamond mesh warp knitted mesh to reduce the scratch on the fish body.
Fish suction pump
1. Working principle
Sucking pump is the main tool used to catch, transport and improve production efficiency in aquaculture and commercial fishing. It is the focus of research on sucking pump to ensure that the fish body is not damaged and improve survival rate. The working principle of the fish suction pump is to use the vacuum pump to pump the air in the pipeline of the system, so that the gas pressure in the pipeline is lower than the external atmospheric pressure, resulting in a low negative pressure. When the wind speed in the suction pipe is higher than the suspension speed of the fish, the fish will be sucked into the fish suction pump with the air flow to achieve the purpose of dry suction and transportation.
In foreign countries such as Norway, Japan, the United States, Denmark, etc., the fish suction pump was initially used in trawling and purse seizing operations, and later gradually used in the cage to catch live fish. It can suction and deliver catfish, shrimp, sea bream, sea bass, tilapia, eel, salmon, cod and other fish. It can suction and deliver 5 tons of mandarin fish, 80 tons of COD, 160 tons of herring every hour, and the maximum suction can reach 300-360 tons / hour, Power up to 190 kilowatts, expensive, mainly suction dead fish. In general, foreign countries install the suction pump and grading equipment on the working boat. When fishing, the working boat is close to the cage, put the suction pipe into the cage, and start the suction pump to suction the fish in the cage and send it to the classifier for grading and counting. The whole operation process is characterized by short time, fast speed, low labor intensity and safe operation.
The unreasonable structure of pump body is one of the reasons for the damage of fish body and the decline of catch quality. In the process of transportation, water circulation is used to ensure environmental health, no pollution, and to ensure that the fish will not rub the rotating impeller, which can avoid damage.