The so-called offshore floating rope cage fish culture is to set floating rope cages in the deep waters outside the harbor, select high-quality fish, and conduct high-density and intensive cultivation. It is a kind of high-quality, high-yield, high-efficiency new cage culture model developed on the basis of traditional fish cages in the Bay. Since September last year, we have conducted offshore floating rope cage fish culture trials in the Jingdou Gewan waters of Lingshui County, Hainan Province. After a period of preparation and the manufacture and installation of cages, four cages of 6m6m6m were On January 12, 2000, 4,503 to 1.35kg of cobia species were put on 4,503 tails, with a maximum of 1,398 tails/carton and a minimum of 845 tails/carton. Feeding 140 days, passed acceptance on June 2, a body weight of 4.25 ~ 3.82kg, up to 5.5kg; average box production 4517.85kg, the highest box production 5941.5kg; output value of 180,000 yuan / box, profit 75,000 yuan / box . The test results show that this breeding model has many advantages compared to the conventional fish culture mode of the inner bay floating cage.
First, the combination of cage design science, breeding environment is good. Floating rope cages are arranged in a single row along the sea outside the port. Not only the water flow is smooth, but also they are not affected by Neiwan freshwater and other pollution sources. The sea water is clear, the water quality is good, and the dissolved oxygen is sufficient. The water temperature, salinity, and pH are relatively stable. .
Second, farmed fish have a strong appetite and grow fast. According to our observations and experiments, the growth rate is at least 1/5 to 1/4 faster than that of Neiwan cage culture. In particular, when the fish grows to 3kg, its monthly weight increases by about 1kg. Put 0.5kg/over fish species, breeding can reach 6 ~ 8kg a year.
Third, there are few diseases in breeding, and the survival rate is high. Due to excellent water quality in aquaculture areas, adequate dissolved oxygen, stable environment, and smooth water flow, in addition to the individual death due to operational damage in the cobia that we cultured, the phenomenon of dead fish is rarely found and the survival rate can reach 99.5%. However, deaths and fish diseases occur in Cobia within Neiwan. In particular, due to changes in the environment such as fresh water influx, pollution of water, transmission of diseases during the period from April to June, various degrees of death occur daily in the breeding process. It is quite serious and even completely annihilated. In addition, we also found that the farming model is also conducive to the recovery of sick fish.
Fourth, the farming density is high, the yield is high, and the benefit is good. According to our experimental results, we speculated that each cage will be fed with 0.15kg/head or more of 1000-1500 cobia species, cultured for 6-7 months, and box production will be 4000-6000kg. The output value of each group will be 150-200 million yuan, and the profit will be 60-80. Million yuan, each box of profit 6 to 80,000 yuan. Unit water indicators such as yield and output value can reach or even surpass the deep-sea potential of fish farming.
Fifth, floating rope cages are able to resist large waves. Floating rope cage system is composed of some ropes, cages, floats, anchors, etc. It is a flexible structure that can fluctuate with fluctuations of wind waves. Second, the cage is a six-sided enclosure that is not easily flooded by the storm and allows the fish to escape. According to our experiments in Lingshui, the aquaculture sea area is often attacked by 5-6 waves of wind and waves, sometimes reaching grades 8-9. However, no losses and impacts have occurred. During the trial, there were no major typhoons, but according to Zhuhai Regional tests, it can withstand the positive attacks of typhoon 11.
Sixth, the masses have a certain fish-breeding basis, with little investment and easy promotion. This model was developed on the basis of fish culture in Nei Wan cages. Its operation and management methods are similar to those of Neiwan cage fish farming. The people have the skills, experience and management basis for cage fish farming. At the same time, according to our budget, the cost of each group of cage nets and facilities is about 120,000 yuan, and about 60 yuan per cubic meter of water, which is lower than the cost of traditional bay-style cages and deep-sea potential grids in Inner Bay. Currently being promoted in coastal cities and counties in our province.
In order to develop floating rope cage fish culture industry, here is a brief introduction to the technology of floating fish net cage fish farming. It mainly includes the selection of breeding sites, the production and set-up of cages, the breeding and feeding of fish species, the type of feed, and the management of feeding and raising, and the harvesting of products.
First, the selection of aquaculture sites Since the cages of this breeding mode are set off the coast outside the harbor, although its structure is a flexible structure with certain wind and wave resistance, it is not possible to set the cage system in a sea area where the storm is too big. , to cause unnecessary loss and operational inconvenience. For this reason, the breeding site is best to have a certain wind barrier or wind waves, the flow rate is about 1m/min, and it is not affected by the inner bay pollution and fresh water. The water quality is good, the environment is relatively stable, sediment sediment, water depth 12～ 20m sea area. Hydrological conditions are: salinity 30 to 35 ppt, water temperature 18 to 32°C, pH 7.5 to 8.5, transparency 8 to 15 m, dissolved oxygen 4.5 mg/L or more, and the water flow rate in the cage is 0.7 to 0.75 m/min.
Second, float rope cage specifications, structure, production and settings.
1. Specification of floating rope cages The length, width and depth of the province currently used are 5.5m5.5m5m, 6m6m6m, 8m8m6m, and 10m10m8m. The combination of cages consists of 10 cages per group and 5 cages per group, arranged in a single row with a group distance of 50 to 100 m. The owner of aquaculture can make decisions based on the sea conditions in the sea area, breeding techniques, management levels, production requirements, labor resources, feed, and funding availability. Generally, each group has 10 cage sizes of 6m6m6m, which are moderate in size, relatively easy to manufacture and operate, and lower in cost.
2. The structure of the cage system, including frames, cages, anchor ropes and anchors, benches (frames), etc., for the convenience of operation and management, can increase traffic dinghies and guarding huts.
3. The production of cage systems is based on the specification of 10 6m6m6m cages per group.
First of all, according to the specifications of the cage system, purchase the relevant network equipment materials, and then start renewing the items for production:
1, the production of flexible frame cage frame is to use two 6~8cm diameter, 110m long Nylon Rope
or 10cm diameter PVC rope (total breaking strength greater than 28000kg) as the main cable and 20 diameter 3cm, Nylon or PVC ropes with a length of 7m (a net length of 6m) are used as auxiliary cables to connect into a group of 10 6m6m cages (3m to 4m in length), and then use a nylon or PVC rope with a diameter of 2 to 3cm. The float rope, the plastic float (diameter 30 ~ 32cm) string together, with a 0.5cm nylon rope or 350 wire Lux rope tied it to the main and auxiliary cables in the frame, each float 40 to 45cm apart, and in each Both ends of the main cable are attached with a floating body (made of 100cm120cm50cm foam or 36-7 floaters), and a floating rope-type flexible cage frame is completed.
2 Production of cages Net cages are made of non-sectioned polyethylene or nylon meshes imported from joints or imported from 56 to 82 mm (2.2 to 3.2, 46 to 58 silk) meshes, depending on the size of the cage being manufactured. Cutting and sewing, assembling a cage with a width of 6m6m6m. The lower part of the bottom surface of the box (the lower edge) and the upper part of the upper box of the box (upper edge) and the side edge of the box are made of two PVC or nylon ropes with a diameter of 1.0cm. The box on the bottom of the force and the side of the box hanging rope with a single 1.2cm nylon rope (rope from 2.5 to 3m) production; mesh stitching and Gang, the use of 50-60 wire rope fixed Lux, Sewing with vinyl or nylon rope. Mesh around the net cover with a 0.5cm nylon string tied tightly to facilitate the closure and fold away; feeding mouth is located in the net cover near the center, on which tied the float or floating body, so that it floats on the water, convenient operation, feeding The suture of the mouth can be made with a live seam, and the method is simple and convenient. The cage of the sinker can be sand bags, tied to the bottom of the cage at the bottom of the four corners and hanging ropes on the location of the next steel, or the diameter of 3.05 ~ 3.81cm (1.2 ~ 1.5 ? ┑ ┑ ┑ 菩 菩 菩)? M6m is called “Wei Mianliang” and “m6m” is tied with 0.5 nylon rope or 350 filament PVC rope, and is fixed around the bottom of the box and tied together with the bottom ring. At the same time, the side steel, force steel and The hanging ropes are respectively tied to the corresponding positions of the sunken frame.
3 Set up and install the cage system in the breeding area of the selected sea area, first make a mark of the position of the cage and the location of the anchoring anchor (determination of the anchoring position, generally the anchor position of the main anchor is the length of the outer water depth projection of the main cable) Above 4 times, the auxiliary iron anchor is located more than 3 times the depth of the main cable projection. After the signs of the cage and anchor are determined, the cage frame that has been completed can be pulled to the mark location and submerged into the water to fix the main anchor (in the end of the main cable facing the storm, three at each end, 250kg and 150kg, respectively). , 150kg; one end of the leeward wave, two at each end, each 100kg). The main anchors are then attached to the ends of the main frame of the cage frame with the main Mooring Lines
. In the same way, on both sides of the cage sub-cables, fix the secondary iron anchors (each 50 kg, then the secondary anchor ropes (3 cm diameter nylon ropes)) to the secondary and secondary sides of the secondary iron anchors and frame cage mouths. The ropes are connected together.Finally, tighten the anchor ropes, and then use a 0.5cm nylon rope to bind the cage to each cage opening in the frame, and put the sideline and hanging rope of each cage. Bundling in the corresponding position of the main and auxiliary cables.
4 Workbench As the cage system is a flexible structure, it is difficult to stand on seedlings, feeding, sample sampling, product harvesting and other operations and management, using four 0.15m0.15m114m High-quality square bar and six pieces of 0.08m-0.10m0.3m8m high-quality wood and 0.5m0.8m1.2m foam or 0.8m-diameter plastic barrel are made into an 8.0m14m floating frame, which is placed on top of the cage frame to carry out Investment work such as seedlings, daily management, and harvesting. As conditions permit, lifting facilities can be added to it.
Third, the release of fish species
1. The selection of selected species of fish species is an important measure for obtaining high yield and high efficiency of fish farming. The varieties for cage culture are mainly based on market demand and prices, convenient source of fish species, rapid growth, and high yields. Consider the maturity of technology and other aspects.
There are many cage fish species, such as red spotted grouper, giant grouper spot, blue grouper spot, spotted grouper, fish, true sea bream, flat sea bream, yellow fin sea bream, black sea bream, barramundi, purple snapper, blue husk. Fish, etc. can be cultured. However, from the current market demand, from the point of view of rapid growth, high yield, and good economic benefits, the main factors are cobia, oviform fish, oyster fish, and bluestone classes. Among them, the most rapid growth of cobia, high yields, and good results .
2. Breeding and Feeding of Fish Species Currently, most of the fish species for cage fish farming are small-size seedlings of 5 to 10 cm purchased from seedlings or seedlings, so small-sized fingerlings are not suitable for large offshore meshes. Feeding of cages is generally performed by artificially feeding high-quality fish gills, small pieces of fish, or artificial feeds. After a period of time, the requirements for large-scale fingerlings are different. Different types of fingerlings are required, but the total The request is slightly larger than the size of the mesh, and it is then thrown into a large cage for commercial fish rearing. For example, in large-scale cobia fish species, small-scale species of 3 to 5 g of 10 cm or so will be cultivated for 3 to 4 months until the fish species reach 0.75 kg 40 to 45 cm or more in large cages for commercial fish breeding. .
3. Feeding density of fingerlings The density of seedlings is determined mainly based on the environmental conditions in the sea area, breeding techniques and management levels, and the product specifications and output requirements of the cultured objects. General yields up to 20kg/m3, up to 30kg/m3. If 20kg/m3 output is used to set the seedling density, the number of seedlings per cubic meter of water, a cage of 6m6m6m, and aquaculture output of about 4000kg. In the case of military cobia, for example, the commercial fish requires 4kg/tail, and the survival rate is 95%. Then, about 1,100 fish species should be put on 0.75kg per tank. Drop density is 5.5 tails/m3. For farmed fish, the specification of commercial fish is 2kg per tail, and the survival rate is 90%. Then, 2300 fish species of 500g/tail are put in each box, and the density of fingerlings is 11~12 tails/m3.
4. Selection and Feeding of Fish Feed for Cage Fishes Currently, the fish cultured in cages are carnivorous fishes, and the fresh fish is an ideal feed for growth. There are varieties of green fish, gardens, and fats. Eyelids, male fish, spots, etc. Although low-value shellfish are also good feeds, they are low in quantity and high in price, making them difficult to use. The use of small shoals of fish in a large fishing port and a good fishing season, a small amount of miscellaneous fish feed is sufficient, but in the more aquaculture areas and fishing poles are not good or off fishing period, the supply of small miscellaneous fish is difficult; while the long-term use of small trash fish The fish resources have been destroyed, so artificial joint bait should be developed and used. At present, the artificially-combined bait has been used in production, and its meat-replacement ratio is 1:1.3 to 1.5, and can be used alone or in combination.
Feeding methods: General fish species can be fed 1 to 2 days before feeding, but due to differences in various fish species and specifications, it is best to vote for seedlings for a few hours and then feed them with some feed. If they can feed, they will be fed. Feeding amount is basically not to eat. Feeding methods should master the principles of slow, fast, and slow. That is, when feeding is started, a small amount should be slowed down to lure the fish to feed. When the fish groups come to snatch food, they should take a lot of quick shots. When some fish are full, they should make a small amount of slow throws. Let the weak fish also feed; when the vast majority of fish do not feed, they can stop feeding.
Feeding time: feeding time is best during the day's tide, if not catch up with the tide, it should be fed above the current, so as not to reduce feed loss. In the growing season from March to October can be fed twice a day, 8 to 9 am, 5 to 6 pm each vote once, small trash fish daily feeding amount of 6% to 8% of body weight, artificial feed of the day Feeding amount is 4%. During the 11 to 2 months when the water temperature is lower, the fish eaten less. They can be fed once at 11 to 12 noon. The dosage can be determined according to the feeding conditions.
Fifth, the daily management of cage fish culture cage fish in addition to daily feeding, but also do the following aspects of the work.
1. Regularly measure the hydration factors in the culture environment and measure the size of farmed fish. Such as the determination of water temperature, dissolved oxygen, salinity, etc., to understand the changes in the water environment; the size of the fish is measured every half or a month to understand the size and growth of the cultured fish and determine its feeding amount. Prepare and plan your drinks. At the same time, we must do a good job on the environmental factors, climatic conditions, species of each species of farmed fish, the number, size, delivery time, type and quantity of feeding, growth and disease records.
2. Clean and replace the cage. The cage system is immersed in seawater for a long time. In addition to the high transparency of seawater, more and more shellfish and oysters, such as barnacles and oysters, are attached to the cage system, blocking the mesh, impeding the smooth flow of water and the exchange of water. Affects the growth of fish and reduces the buoyancy of the cage system. Therefore, in day-to-day management, cages are often cleaned or replaced depending on the condition of the attachments to the cage system and the size of the fish. The method can be artificial or high pressure water jet. Replace the cage, first soak or dry with fresh water, then beat the scrub; can also use some chemical drugs or anti-fouling paint, soak the mesh, prevent or reduce the attachment of attached organisms to reduce the cleaning and replacement of the cage Labor intensity. As for the number and time of cage replacement, it depends on the attachment conditions of various sea areas and attachments. According to the conditions of our tests, if the mesh is not painted, it is usually cleaned or replaced once a month or so. . From stock raising to commercial fish sale, cages should be replaced 4 to 5 times.
3. Do a good job of safety inspection. Since cages are installed in the sea, they are often affected by wind and waves. It is not always possible to see the damage, attachment, and fish movements of the cages on the water surface. Therefore, check and observe the attachment of the cages, including observation on the water surface and diving observations. Whether or not there is a breakage loop, the fixation of the cage system, and the growth of fish, etc. Always pay attention to listening to the weather forecast, especially before the arrival of the typhoon, take defensive measures, check and increase the anchorage force, reinforce the fixed system of the cage, if there is an oversized typhoon, we must use the ship to drag the cage into the inner bay to shelter from the wind until the typhoon. Afterwards, the cage was pulled back to the original culture area. In addition, there are many fish around the cages, and fish-fighting is strictly prohibited.
4. Prevent disease measures. Although this model is located offshore, the water quality is good, the environment is stable, and the disease is relatively small. However, since the cage fish culture is intensive, the density is high, and the bacteria is easy to spread, we must adhere to the principle of general prevention. Good preventive measures. First of all, be careful with the operation, be light and do not damage the fish. In normal times, the debris near the cage should be promptly removed. Observe the feeding and activities of the fish groups. If diseases or dead fish are found, they must be timely treated and fished out, destroyed, buried deeply, and not thrown at sea; When feeding, do qualitative, regular, quantitative, do not feed the rotten degenerate feed, and according to the changes of the season and water temperature, fish size, appetite, quantitative feeding, it is best to add antibacterial drugs in feed for feeding In order to reduce the occurrence of fish diseases, it is necessary to keep the breeding environment clean and free from contamination, and it is better to establish a water quality monitoring station in the sea areas with a large area of aquaculture to monitor and forecast the water quality environment in the sea area. Since no fish diseases have been found in the current culture, the prevention and control techniques for various fish diseases are not described here.
6. When will the harvest cage fish be collected and listed? How to transport the fish? Due to the different cultured species, the market specifications are different, and the breeding cycle is even more different. General adult fish farming time is about 6 to 12 months. In the general market specifications in Hainan: groupers, squid, real oysters, oysters, purple snappers, etc. are more than 500g, black bream, yellow fins are more than 200g, fish more than 1000g, more than 4000g of cobia, reach the above specifications, Higher fish prices can be collected and listed. When the cage is lifted at the time of harvest, it can be fully harvested or harvested. Live fish transport is basically completed using a live water boat. The method is similar to the transport of fish species, that is, the use of a live water cabin, plus pumping and aeration. Generally, a live-water boat with a weight of 20 tons can be loaded with 3 tons of fish in summer and 4 tons of fish in winter, and frozen fish can be shipped in frozen vehicles. The load depends on the load of the car.