The way of raising adult rainbow trout

Rainbow trout adult rearing methods are mainly the following:

1. High-density running water pond trout breeding This is currently widely used at home and abroad breeding methods, it has a small footprint, save manpower and material resources, high utilization rate of bait, high yield advantages. 2. Raising trout in deep low temperature water of gaoba reservoir. The water temperature of Gaoba Reservoir is directly proportional to the water depth. The surface water temperature is high and the bottom water temperature is low. The trout can be cultured in net cage near the downstream channel of Gaoba reservoir by using the deep low temperature water from power generation or irrigation tunnel. (1)Farming conditions. Xin 'anjiang reservoir dam downstream 20 kilometers, sufficient flow, water plants, small fish and shrimp a lot. In recent years, the growth of warm water fish there is decreasing day by day, but the cultivation of rainbow trout has unique conditions. In January 1980, Zhejiang Jiande County Fishery Administration introduced 30,000 rainbow trout eggs from Taiyuan to hatch locally, and 10500 larvae hatched. On April 5 of that year, they were removed outdoors and transported to the river 3 kilometers downstream of Xin 'anjiang Dam for breeding in cages. The water temperature of the breeding site is 9℃-20℃, the monthly average temperature changes from 10.3℃-16.2℃, and the water flow velocity is 0.2 meters per second when the water flow is urgent. During the cage rearing process, 6000 escaped into the river accidentally, and 4500 were kept in the cage by December, with an average weight of 75.7 g. By November 1981, more than 4000 adult fish had been cultivated, with an average weight of 880 grams. By December 1983, the average weight was 2400 grams. (2)Cage size and stocking density.① Brood fish cage. The specification is 4 m ×4 m ×1.7 m, the area is 16 square meters, the water volume is 24 cubic meters, the mesh is 4.5 cm, and it is woven with 3×4 polyethylene silk. The stocking density was 10 per square meter and 6 per cubic meter. Use a 9 cm mesh mesh as a cover net. The net mesh of parent fish cage is larger, mainly considering that small miscellaneous fish can enter the net cage and can be used as rainbow trout bait. 2. Adult fish cage. Specifications 4 m ×4 m ×1.7 m, area 16 square meters, water volume 24 cubic meters, mesh 3 cm, with 6 cm mesh to do cover net. The mesh is woven from 3×4 polyethylene filaments. According to the experiment in 1981, stocking density of 100 fish and 63 fish per square meter had little difference in growth rate and survival rate of adult fish. In 1983, 125 fish were stocked per square meter, and the specifications of fish entering the box were more than 50 grams.③ Fish cage. The fish net cage is divided into two levels, and the fish net cage of the first level has the specification of 2 meters ×2 meters ×0.7 meters, the area of 4 square meters, and the water volume of 1.6 cubic meters. It is made of 16 mesh polyethylene net system per square meter. One edge is not sewn as a bait feeding opening. The first-class box contains fish species below 11.5 cm, and the stocking density is 2500 fish per square meter. When the species grow to more than 11.5 cm, move to the secondary species box. The second box specifications are the same as the first box, made of 1.5 cm mesh, and the stocking density is 400 tails per square meter. This kind of design of the fish box mainly considers that the mesh is small and easy to be blocked by the green mud moss. It is easy to turn the box in the water. The bottom of the box is used as a cover. After the sun dries, the green mud moss falls off, and it can prevent birds from harming. In case the net cage sinks into the water, it can also prevent fish from escaping. The net cage uses bamboo frame, adopts floating type. (3)bait. Xin 'an River rainbow trout farm trout feed is the use of local cheap pig blood, mainly pig blood and wheat bran, with fish meal, water grass and so on. The feed system of fish was 2.74 at fingerling stage and 3.05 at adult stage. Adult fish and parent fish were fed twice a day, and the feed cost was 0.66 yuan per net increase of 0.5 kg fish. 3. Transplanting and releasing rainbow trout in mountain stream river. Rainbow trout is native to mountain streams and feeds mainly on insects and small miscellaneous fish, while most of the small fish with low economic value in mountain streams. If rainbow trout is transplanted and released to such waters, it will not spread arbitrarily due to the limitation of its own living water temperature threshold, so it can obtain the effect of transforming low-grade miscellaneous fish into high-grade fish. In 1983, the Department of Water Resources of Sichuan Province began to conduct transplantation and release experiments of rainbow trout in Dahaizi and Jiulongzhai Nature Reserve of Minjiang River. 4. Rainbow trout culture in seawater cage. In recent years, the development of trout culture in seawater cage is relatively fast. In 1982, Norway raised about 400 tons of seawater trout, France about 700 tons, Denmark, Japan and so on also prevalent trout. The cage specifications used are 10 m ×10 m ×10 m, 7 m ×7 m ×3.5 m, etc. The stocking density is 4-5 kg per cubic meter, the production is 15-20 kg per cubic meter, and the breeding period is from October to June of the following year. When the seawater temperature reaches above 18℃, it will come to an end. Danish marine cage culture generally stocks 200 grams of rainbow trout in April and grows to 2-3 kilograms in January of the following year. North Korea has also succeeded in domesticating trout in seawater, which only needs to be surrounded by barbed wire or ordinary fishing nets at the seaside. In 1983, Linqu County, Changdao and Dalian Aquatic Products Company of Shandong Province also carried out the experiment of raising trout in seawater field. Rainbow trout grow 1.5 times faster in seawater than in fresh water.