Oval oysters? Marine cage culture technology
Abstract : Oviform oysters is an important seawater aquaculture species in South China. It has high food and commercial value. This paper describes the main methods of egg culture and disease prevention in sea cage cage culture. The successful breeding provides a certain reference basis.
Key words: Oviductus; cage culture; disease control
Ovule is a pheasant, a family, a genus, also known as golden pheasant, yellow laminar, etc., because of its delicate meat, delicious taste, rich nutrition, favored by the Southeast Asian market. Oviducts have the characteristics of rapid growth, strong ability to adapt to the environment, and high survival rate. In general, when they were farmed in the same year, they can meet the specifications of listed commodities and have significant economic benefits, which has been welcomed by the breeding industry. With the development of artificial breeding and aquaculture technology, the oval shape has now become a kind of economic fish widely bred in the southern coastal areas of China. Oviductus cultivation methods mainly include cage culture, pond culture, fish breeding, etc. In recent years, the scale of cage culture in the coastal areas of Hainan and Guangdong in China has been continuously expanding. Therefore, the following are mainly oval patterns. ? A simple summary and introduction of cage culture techniques.
1, the choice of the sea area and the preparation of cages
The cages for breeding eggs should be selected in areas where there are certain wind barriers or wind waves are relatively small, the water flow is unimpeded, the water body is fully exchanged, is not affected by the fresh water and pollution sources of the inner harbour, the water quality is refreshing, and the water quality environment is relatively stable. The depth of water is generally required to be between 10m and 15m (after falling tide). If it is a deep-water cage, it can be set in a sea area with a depth of 20m or more. Generally, it must be ensured that the distance from the bottom of the cage to the seabed should be at least 2m above the minimum tide. . To ensure the success of farming, the water quality in the aquaculture sea area should meet the following conditions: salinity 20 to 30, water temperature 18 to 32, pH 7 to 9, transparency 8 to 15 meters, dissolved oxygen 5 mg/l.
Farmed eggs are generally made of polyethylene mesh wire braided. The mesh size is 2.5 to 3.0 cm. The size of the cage can be adjusted according to the size and actual conditions of the fry, ranging from 3m 3m 4m to 4m 4m 4m. With the popularization and application of deep-sea cages, it has been proved that oval-shaped cages are also suitable for such cage culture. Therefore, in deep sea areas, deep-water cages made of high-strength polyethylene (PE) up to 20 meters in diameter can be used for aquaculture. According to the size of the cage and the different situations of tides and waves, a single cage can be fixed at a single point, or multiple cages can form a grid row. The grids composed of multiple cages should maintain a suitable spacing, and the general requirements are more than 3 meters. To ensure the smooth flow of water.
2. Stocking of fish species
From the southern area to April-May, when the water temperature rises and stabilizes at above 18°C, it is the appropriate time for the species to be released. The stocking densities of oval eggs should be flexibly controlled according to the conditions of water quality and environmental conditions in the sea area, breeding techniques and daily management levels, sources of feed, and indicators such as output and specifications. In general, if you want to harvest early, about 10 cm in length of the fry, can be released as 40 to 50 / m3 of water, if you do not rush to harvest, can be appropriately increased breeding density.
3, feeding and management
3.1 feed feeding
Oviforms are carnivorous fish. In the past, they mainly used minced fresh fish for feeding. However, they can also be fed with compound feeds for a good breeding effect. At present, high-grade marine fish puffed compound feed is commonly used for cage culture.
Gold carp eats large amounts and digests fast. Under captive feeding conditions, after eating for a short period of time, if they are fed with their favorite food, they are still fiercely contending. Therefore, the daily feeding amount at the appropriate temperature for the growth of the water in June, July and August can be controlled to be more than 20% of the fish body weight, and the feeding amount can be appropriately reduced in other months when the water temperature is low. There are also some farmers who want to grow quickly, compress their growth cycle, and increase their daily feeding amount to 40% of their body weight in the hot season by increasing the number of feedings.
3.2 Daily Management
The day-to-day management of cage aquaculture needs to be “five-minded and detailedâ€, that is, diligent observation, diligent inspection, diligent inspection, diligent washing and diligence, disease prevention, patience and meticulous feeding, and prevention of accidents such as gale, pollution and man-made accidents. occur. It is necessary to regularly inspect the cultured eggs and observe the fish activity, water color, and water quality. Generally, water temperature and air temperature should be measured every morning, evening, and night. PH value should be measured once a week and transparency should be measured twice. Every 15 days or 20 days or so, the body length and body weight of the egg pods are sampled and measured to determine the growth rate, regularity, etc., and it is easy to determine the feed amount of the feeds. At the same time, check the oval worms for fish diseases. .
In cage culture, cage cleaning and replacement are very important tasks. In cage systems that have been immersed in seawater for a certain period of time, barnacles, oysters, shellfish, and algae are more or less attached, which, to a certain extent, impedes the flow of water and the exchange of water, thus affecting the eggs. The growth of the shape and weight of the cage system has increased. Therefore, in daily management work, network replacement and cleaning should be carried out according to the attached biomass and fish culture on the cage. Generally, the net is changed from 3 months to 6 months. When the net is changed, it is necessary to prevent the farmed fish from being caught in the net corner to cause scratches and death. The operation must be meticulous. Cage cleaning can be performed using high-pressure water gun spray, fresh water soaking, and exposure.
3.3 Harvest
The eggs hatched in the year were generally laid at 10 cm or so, and the product specifications of more than 400 g could be reached within 4 to 5 months of breeding. In general, the market price for oval eggs is better than 600g/tail, so it is recommended to harvest at this time. In addition, farmers can determine the timing of the start of breeding or the size of seedlings, based on the growth status and market predictions of the eggs, in order to obtain the maximum benefit.
4. Fish disease control
Diseases of the oval shape are relatively rare, and the prevention and treatment of disease should adhere to the principle of “prevention from prevention, prevention and control from combiningâ€. When stocking, the seedlings must be sterilized. Specifically, the fish should be washed with fresh water or a solution of 0.1 mg potassium permanganate per liter for 10 to 15 minutes before the seedlings are released. In addition, we must adhere to the inspections, and pay special attention to observing the swimming and feeding conditions of the oysters, fish and fish. Once they are found, the dead fish should be treated in time or treated in a harmless manner (such as deep burial). Do not use it at will. Throwing out of cages spread the disease and caused greater harm. At present, the common diseases in oviform cages are small echinococcosis and ringworm disease.
4.1 Scyllophobia
Diseased fish appear on the surface of the body with 0.5 mm to 1 mm in diameter white spots, increased mucus, scales fall off, anorexia, small melon worms in the cercaria parasite destruction of small pieces, cause the fish to breathe difficult until death. At a water temperature of about 30 °C, white spot infection spreads quickly, and the entire cage or fish pond's oval shape can be infected within a few days. The pathogenic body is a stimulating Cryptocaryon irritans.
Prevention methods: bath with fresh water for 5 minutes to 10 minutes, or use 10010-6 concentration of formaldehyde seawater bath for 30 minutes to 1 hour, 3 days to 5 days.
4.2 The ringworm disease
The fish's body surface is dull, loss of appetite and slow swimming. Some fins fester, mucus increases on the surface and the sacral area, local scales fall off, and the eyeballs on one or both sides protrude, become inflamed, necrotic, or fall off. The swimming loses its balance and turns around. The pathogenic body is a ringworm.
Control methods: Dipping with fresh water for 5 minutes to 10 minutes, once a day for 2 days to 3 days, the effect is good.
5. Safe production
The safety of cages should always be checked during the cultivation of oval cages in sea cages. Water-surface and underwater (dive) observations should be used to check the attachment of the cage system frequently. Whether the cage is damaged, whether the various cables are worn or not, and whether the fixed facilities of the cage system are firmly fixed, etc. Take appropriate measures and deal with it in time to prevent it from happening. Prior to the occurrence of severe weather, it should be used to cover the net; check and adjust the tension of the anchors and piles, reinforce the drawstrings and the fixed ropes of the cages; check the firmness of the frames, anchors, and piles; and move the cultured personnel and ships to shelters. And other measures to prevent.
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