Before the reservoir is stocking economic fish, it is necessary to build fish blocking facilities at all the water inlets and outlets of the reservoir, and strengthen daily management and maintenance to prevent fish escape accidents. Reservoir fishing facilities mainly include net fishing facilities, electric fishing facilities, and bamboo and wooden fishing facilities. Net fishing facilities have the advantages of good fishing effect, simple equipment, low cost, convenient installation and management, and are widely used. The net length and height of the blocking net should be increased by 10-15% respectively than the actual width and depth of the interception. The size of the net depends on the size of the stocked fish. The horizontal shrinkage factor is generally 0.6-0.7, and the piling type is usually adopted. It can be installed and fixed in two ways: and anchored. The electric fish catching facility is designed according to the principle that fish can avoid the electric grid. When the fish swims to the electric grid and encounters a certain intensity of electric field, they will be stimulated by electricity to change their swimming direction and play the role of catching fish. Bamboo and wooden fences for catching fish have the advantages of convenient materials, simple construction, and low cost. However, they cannot withstand the impact of large-flow floods and have poor safety performance. They are rarely used now.
1.Selection of stocking species. There are a large number of plankton in most reservoirs in my country. Therefore, silver carp and bighead carp are the main breeding objects. In order to make full use of other food resources, omnivorous carp, crucian carp and herbivorous grass carp, mainly benthic animals, can also be stocked. Bream and so on.
2.Size and quality of stocked fingerlings. If the fish species placed in the reservoir are small in size, they will often swim in groups after entering the reservoir. They will have difficulty eating bait, have poor foraging ability, and grow slowly. At the same time, they have poor adaptability to changes in the external environment and are easily preyed by ferocious fish. , So that the survival rate is low, and the recapture rate is not high, which directly affects the fish production capacity of the reservoir. On the contrary, if the size of the fish species is larger, the above situation will be significantly changed, and the growth rate of the large stocking size is faster, but another The larger the size of the fish species, the higher the production cost required. Therefore, localities can make appropriate regulations according to their own conditions, the size of the reservoir, and the degree of harm to the ferocious fish. my country's current requirements for fingerling specifications are generally: silver carp and bighead carp 11.5-13.2cm, grass carp 13.2-14.8cm, carp and bream 6.6-8.3cm. The fish species put into the reservoir are required to have neat specifications, lively swimming, strong physique, and disease-free.
3.Stocking density and matching ratio. Large and medium-sized reservoirs are large in size, deep in water, large in storage capacity, and the ecological conditions of fish are extremely complex and difficult to control. They mainly rely on the natural bait in the reservoir for extensive cultivation. The stocking density and matching ratio are mainly determined by the nutritional type of the reservoir. Eutrophic reservoirs can hold 110-140 fish per mu, of which silver carp accounts for 35-40%, bighead carp accounts for 50-55%, grass, carp, bream, etc. can account for 5-15%; general nutrient reservoirs, each 80-110 fish can be stocked per mu, of which silver carp accounts for 30-35%, bighead carp accounts for 55-60%, grass, carp, bream, etc. can account for 5-15%; oligotrophic reservoirs can store 50-80 fish per mu Among them, silver carp accounts for 25-30%, bighead carp accounts for 60-65%, grass carp, bream, etc. can account for 5-15%. For small reservoirs, because of its small area, convenient fish farming management, and the lack of deep water, it is conducive to the reproduction of bait organisms and the growth of fish. The number of ferocious fishes is small and easy to remove. The fish farming production can be divided into sparse and extensive. There are two ways of breeding and intensive breeding. The sparse and extensive culture generally stocks 80-100 fingerlings of 13-14 cm per mu, of which silver carp accounts for 40%, bighead carp accounts for 50%, grass carp accounts for 4%, carp and braided fish each account for about 3%.
The reservoir has rich water resources, vast waters, sufficient sunshine, and good water quality. It is very suitable for aquaculture. However, in order to have high yields and good benefits, scientific breeding must be adhered to. The main points are as follows:
1.One is to stock fish species reasonably. In reservoir farming, it is required to invest in high-quality, healthy, disease-free, large-sized and neat high-quality seedlings. Generally, the size of fry is more than 15 cm. This kind of fry grows fast, has a high catch rate and good economic benefits. If seedlings with weak and small specifications are put into use, not only will the survival rate be low, the feeding ability will be poor, the growth rate will be slow, and the catch rate will be low, and they will be swallowed by the ferocious fish in the reservoir. The stocking density should be reasonable and should be flexibly controlled according to the reservoir conditions and the level of aquaculture management. Generally, 150-200 large-size fry and 350-500 small-size fry are invested per 667 square meters. The stocking time should be stocked every winter, generally around January each year, when the transportation survival rate is high, and the fish can be stored early and grow early to increase the growth time. When the weather is fine, the seedlings should be stocked in the shallow water where the upper reaches of the reservoir is protected from the sun and wind.
2.The second is scientific feeding and fertilization. Reservoir fish culture is generally based on filter-feeding silver carp and bighead carp. The method and amount of fertilizer should be determined according to the characteristics of its staple food plankton, climate change, temperature difference and water nutrition status, etc., to ensure a reasonable balance and scientific fertilization. The water color of the reservoir is oily green or light green. Generally, the water body transparency of large reservoirs should be between 80 cm and 100 cm, medium-sized reservoirs between 60 cm and 80 cm, small reservoirs between 40 cm and 60 cm, and Shanping ponds between 30 cm and 40 cm. Fertilization generally uses organic fertilizer or inorganic fertilizer, and can also apply biological fertilizer according to conditions. Fertilization should grasp the principle of "apply sufficient base fertilizer, timely topdressing, and less frequent application", and more topdressing should be applied during the peak season of fish growth. If feeding fish are stocked in the reservoir, they should be fed scientifically in accordance with their feeding requirements.
The third is to strengthen the prevention and control of fish diseases. Once a fish disease occurs in a reservoir, it is very likely to harm the entire reservoir and cause great losses. Therefore, the principle of "prevention first, prevention is more important than cure" should be implemented for fish culture in reservoirs. Before the fingerlings are stocked, the reservoir should be disinfected with quicklime and bleaching powder. In the hot season or when the water quality deteriorates, measures should be taken to adjust the water quality, and the fish diseases should be treated promptly. The more common fish diseases in reservoirs mainly include viral fish diseases and bacterial fish diseases, and outbreaks, enteritis, gill rot, red skin disease, printing disease and water mold are the most common. After the fish disease occurs, the professional and technical personnel should be asked to make a correct diagnosis and treat the symptoms.
The fourth is to strictly strengthen management. The area of the reservoir is relatively large, the environment is complex, and the management is difficult. Therefore, management is also a key factor affecting benefits. It is necessary to patrol the reservoir day and night, strengthen the duty to eliminate various hidden dangers; strengthen the management of the water inlet to prevent pesticides and other pollutants from entering the reservoir; check the escape prevention facilities of the reservoir, especially during the flood season, to guard it; strengthen inspections, at any time Grasp the growth of fish and the changes in the water body, and deal with problems in time when problems are found; prevent illegal fishing activities such as stealing fish, electric fish, fried fish, and poisoned fish.