The research of geoduck culture technology
The research on geoduck culture technology is a scientific research project issued by the Shandong Provincial Science and Technology Commission in 1999. Geoduck is native to Canada and the United States on the North Pacific coast. The Shandong Marine Fisheries Research Institute introduced seed hoe in 1998, and succeeded in artificial seedlings the following year. It has been more than 10 years in the coastal areas of Liaoning and Shandong since 1999-2002 for four consecutive years. Units were farmed. In recent years, the Provincial Science Committee has organized experts to carry out on-site inspections and appraisals several times, and has fully and excessively fulfilled the planned targets, which are summarised as follows: (1) The ability of seedlings to withstand dehydration and the method of transportation 1.1 The ability to withstand dehydration is similar to that of pulling seedlings. The dew capacity is shown in Table 1. At a temperature of 18.6 to 21.4°C, a shell with a shell length of 6 to 8 mm has a survival rate of 52% in the shade for 24 hours; a cotton soaked in seawater is kept moist, and the survival rate in the trunk at 24 hours is 86%. Hours all died. In addition, we also observed the oxygen tolerance of the seedlings. At a temperature of 20-24°C, 50 shellfishes with a shell length of 2 cm and a weight of about 3.2 g were released in 400 ml of seawater. The water pipes extended normal and survived within 32 hours. 48 hours abnormal extension of the water pipe into a flat shape, and can not be retracted, was paralyzed, at this time continuous exchange of water 2 times, but also normal life; 64 hours of all seedlings died, the seedlings became dark, the water pipes were linear . 1.2 Method of transport In the production of shellfish can be dry transport, but also wet transport. Seeds with 5 to 10 mm long shells, dry towel, or foam (about 0.5 cm thick) soaked in seawater at the bottom of the foam box. Put the seedlings on the bottom and can hold 3-5 layers of seedlings. 50,000 tablets; wet transport in the foam box placed polyethylene film bag, containing 4-5L of clean seawater, each bag put about 50,000 seedlings, and then oxygen, add ice, sealed and transported. Using these two methods to transport seedlings, the survival rate can reach more than 95% after 20-24 hours, but the speed of submerged sand for wet seedlings is fast, and it can be buried in about 5-10 minutes. The speed of slow-moving seedlings for dry transport is about 10-20 minutes slower. 2 In the aquaculture sea area of ​​the aquaculture area, inner bays with small waves and rich bait, mainly sand, should be selected. The aquaculture water depth can be from about 10m below the low tide line, the water temperature in winter is not lower than O°C, and the water temperature in summer is not higher than 25°C. The composition of the substrate in the cultured sea area (Table 2) has a great influence on its survival and growth. The sediment content in the cultured sea areas of Changli County and Changzi County in Dalian accounted for 85%-90%, and the growth of pupa was normal. The survival rate for breeding for 2 years reached 27% and 16% respectively. The content of sand in the bottoms of Ma Lan Bay, Rongcheng City, Shandong Province accounted for 91%, and the growth was normal. The survival rate in 2 years was 15%. However, the content of Sand in Sanggou Bay was 74%, and the content of mud in the Sanggou Bay accounted for 26%. The seedlings cannot grow normally and the survival rate is less than 2%. Secondly, the content of sediment in the bottom sediment is high, and the shells and water pipes that are grown are dark brown in color, and the quality of the products is poor. When the sand content is high, the milk is yellow or white and the quality of the products is good. 3 Breeding methods 3.1 The seedlings with different seed size and seeding time are shown in Table 3. The shell length of 3 to 15mm has the ability for dive burrowing. Individuals have large dive rates, but the burial depth is relatively deep. Individuals dive quickly, but buried shallow. The 4-8mm shell length seedlings have the strongest sedimentation ability, which takes only 3-5 minutes, and the latent sediment rate can reach 100%. The seedlings with the shell length more than 20mm will lose their burrowing ability due to the deterioration of their feet. The sedimentation capacity of seedlings at different water temperatures is shown in Table 4. The sedimentation capacity is the strongest at the water temperature of 1l-17°C, the water temperature is less than 9-C, and the sedimentation capacity is greater than 23-C. In addition, salinity has a significant impact on the ability to extract sediments from sand dunes, salinity at 27-32 sediments is normal, and when salinity is below 26, sedimentation capacity declines drastically. It can be seen that, when the geoduck cultured, the seed size is suitable for the shell length of 4-8mm, and the seedling propagation time should be from May to July in the spring and summer season. 3.2 Methods of culture Since the four-year breeding experiment from 1999-2003, we used three methods: submarine rearing, net basket care, and plastic tube care. The results are as follows: 3.2.1 In the past 4 years, we have been reunited with the islands in Long Island County, Shandong Province, in Long Island County, Shandong Province, in Yeou Island, Zhifu District, Penglai Development Zone, and in Malanwan and Dongji Islands in Rongcheng; Liaoning The submarine rearing trials were conducted on the submarine sowing sites in the sea areas of the governors of the islands of the islands of Cheri, Zhangzi, Wuji Island, Dajia of Jinzhou District, Bangmao Island and Lingshui Town in Zhongshan District. There are 44.733 million seedlings, 5,381 acres of sown area and 8300 seedlings per mu. In May 1999, Dalian Keyang Aquatic Products Co., Ltd. broadcasted the geoduck seedlings of our pond in April 30th in the sea area of ​​Seri island. The seedling volume per mu was about 10,000, and its growth was shown in Table 6. After seeding, seedlings grew better than Shah, but when they were examined at the end of September, the number of seedlings drastically decreased, and the survival rate was reduced to about 20%. After 3 years of propagation, the average shell length reached 12.7 cm and the weight was 526 g. The survival rate is only 12.1%. The main cause of death is eaten by enemy creatures. 3.2.2 Net basket care In order to improve the survival rate of seedlings for seeding, in June 2000 in Dalian Yulin Marine Culture Co., Ltd., in July 2001 in the Houying area of ​​Penglai City, a 4m X 4m rack welded with 10mm steel bars was used. Polythene nets with a 1cm outer cover are used for protection. Each basket has 40 baskets, and each basket has 1,000 pellets. The average shell length was 10.7cm in 2 years and the weight was 207.3g. The survival rate was only 12.6%. The reason for the death was that the net basket was under the impact of the waves and there was a hole in the sea floor. There were crabs, red snails, crickets, starfish and other enemies in the basket. Harmful creatures. 3.2.3 Plastic tube care Due to the low survival rate of submarine rearing and net basket care, in 2001 we adopted the method of plastic tube cover netting to “plant†geoduck and achieved very good results. The nursing plastic tube is 10-20cm in diameter, 25-30cm in length, inserted in the sand of the submarine at 20-25cm, and exposed at the upper end of 5cm. It is sealed with an extruded plastic mesh with a hole diameter of about 1cm. The mesh and the wall are bound with rubber bands. The tube distance is 50-60cm, 2400 cans are inserted in 1 mu. Plug the tube first, then plant the seedlings. After the “planting†for 3-4 months, the depth of the burrowing will reach half of the length of the tube. After 6-8 months, the seedling has burrowed under the tube. At this time, remove the nursing tube (reusable ). Seedlings in the sand, 20-25cm deep, have strong concealment protection capabilities. Later, they rely on their own sports to gradually dive and evacuate. The growth of tuberculosis is shown in Table 7. The average length of the shell is 5.08cm in one year and the body weight is 52.1g. Although the growth rate is lower than that in submarine rearing and net basket care, the survival rate is 60%, which is increased by 4 times. . Among the three breeding methods we tested, the survival rate of intubation care is the highest, and the best results are the most promising ones.
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