Crassostrea gigas is a wide-salt and wide-ranging inner bay shellfish. It has the characteristics of large individuals, fast growth, high yield, and strong adaptability. It is a sea food that people like to eat. Pingyang County, Zhejiang Province has a smooth flow of water in the South Bohai Sea area. It is rich in food, and its water temperature is suitable for Pacific oyster farming. To explore the potential of this variety in the South Bohai Sea, we have conducted a study on the Pacific oyster longline culture techniques. These are summarized below.
I. Aquaculture areas and their natural conditions are farmed at Guosheng Island and Mazu Bohai District on Lamma Island. The average water depth in the sea area is 2.87m. The muddy sediments have an average annual water temperature of 18.7°C. The monthly maximum water temperature is 27.8. °C (August), the minimum is 9.6°C (February), seawater salinity averages 30.46 年, and the monthly average salinity is 33.07 ‰ (July-August), the monthly minimum salt The degree is 27.07 ‰ (November). The tide is a regular half-day tide with an average tidal range of 3.74 m and a tidal current speed of 0.29 m/s. The currents are mainly affected by the warm currents of Taiwan (black tide branch), the coastal currents of Zhejiang and the runoff from the sea, and the transparency of the water is greater than 2m in summer and autumn. The winter and spring seasons are larger than 1m, and the pH value is generally between 8.05 and 8.40. Seawater is rich in nutrients. The annual average amount of phytoplankton is 4.3x105/m3.
Second, truss settings and breeding equipment
1.ç Set to downstream.
2. Floating rafts are mainly composed of floating stems, floats, anchor stems, and piles (anchors). Floating stems are made of polyethylene ropes and have a length of 60m and a rope diameter of 2.8cm to 3.0cm. The anchor stem adopts the polyethylene rope, the diameter is 2.8cm--3.0cm, the length is 2 times - 3 times of the water depth when the tide is full. Floats are made of glass balls, plastic balls, etc. They are 28cm in diameter, and each floater needs 30 floats. The pile is made of bamboo tube, mixed wood or drop stone with a length of 120cm--150cm and a diameter of 15cm--20cm.
3. Other culture ropes use polyethylene ropes with a diameter of 5mm. The lifting ropes are 1.2m to 1.5m long. Each attachment base (shell) is 15 and each float is hung by 150.
Third, seed sources and transportation
1. The first batch
On December 18, a total of 160 oysters were returned from Luoyuan, Fujian Province, and 100 shells (attached bases) were hoisted. The seeds were attached to shells of oysters, dried and transported for 15 hours, and seawater was sprayed on the way. After being held in shrimp ponds for a period of time, they were transported to Nanxun holding on January 11 of the following year.
2. The second batch of mid-November the following year, the introduction of oyster seedlings from Lianjiang, shipping, because the seedlings have been completed and directly into the breeding period, the seed size is like sand size.
Fourth, seedlings and seedlings to cultivate the seedlings on April 18 of the following year began to split seedlings, each hanging 15 shells, interval 10cm or so, after inspection, each shell with seedlings 3 - 4 seedlings, seedlings rope Using a nylon cord with a diameter of 0.5 cm, the second seedling was performed in late May.
V. Routine management First, the sludge should be washed in a timely manner during the seedling period so as not to suffocate the seedlings. The second is to remove the attachments of the oyster surface in time. During June-July, as the water temperature rises, there are more oyster attachments and poor water flow, which hinders the oyster's filter food, and competes with oysters for bait, which affects the growth of oysters, and should be handled with care when washing. Seedlings fall off; Thirdly, to prevent winding and falling off of hanging ropes between cranes and hoists, timely conduct safety inspections on cables, floats, stakes, and seedlings, etc., and find that problems are solved in time. Fourth, during the growth of oysters, timely seedlings or buoyancy should be added to reduce the tolerance of the oysters.
Sixth, the test results The first batch of seedlings were cultured until August 16 of the following year, the shell height was 6.34cm, and the body weight was 31.0g. By September 25, the shell height was 7.35cm and the weight was 64g. On August 28, the height of the shell was measured 8.87 cm and the body weight was 69.35 g. Pacific oysters continue to breed for one year after reaching product specifications. Individuals do not gain weight. It can be seen that there is no production significance for continuous breeding for one year. The growth of Pacific oysters in the South Bohai Sea is from April to November, and the individual grows fastest from June to September.
The second batch of seedlings was cultured until August 27 of the third year. The height of the shell was measured to be 7.26cm and the weight was 64g. Generally, the weight per heave was 3.0kg--3.5kg.
Seventh, summary and discussion
1. The test results show that the longline cultivation of Pacific oysters in the South Bohai Sea is feasible, with the advantages of rapid growth, high yield, high meat yield, short breeding cycle, and avoidance of typhoons. After aquaculture in recent years, the production capacity and production potential of Pacific oysters in the South Bohai Sea area have been ascertained. The yield per mu can reach 5 tons, and the seedlings can be planted in the fall. The product can be sold in summer for 31g in the summer and before the typhoon season. Can be harvested.
2. Several factors affecting production: (1) Time of seedlings. When the seedlings are subcultured twice, the seedlings will not affect the growth of the oysters when they are unripe, and the growth environment of the oysters will be improved after the seedlings are separated, which will increase the aquaculture production. (2) Attachments. Many attachments were found in the breeding process, such as indirect damage to oysters by sea anemones, barnacles, bryozoans, and lime worms. They competed with oysters to compete for sessile roots, affecting the fixation and growth of oysters, as well as directing of species such as crabs and crabs. Harm oysters. In production, sun exposure, fresh water bathing, or adjustment of hanging water layers or inversion can be used for control purposes. (3) Seed quality. Seed quality directly affects the production of oysters. Seed selection first checks whether each shell is attached to the seedlings in a uniform manner. Generally, each shell contains 10 or more seeds to account for 90% of the seedlings, and secondly, it is necessary to gently touch the seedlings to see if they fall off. The robust seedlings are not easy to fall off, and the color is dark brown, and the seedlings are easy to fall off and mostly white. (4) Time for seedlings to be released.
3. The study of Pacific oyster culture mode in the South Bohai Sea Region: (1) Time of advancement. In the autumn, the planting time is October-November, and the seedlings can be transplanted as soon as possible after the typhoon season to extend the growth period of the seedlings in the South Bohai Sea area. (2) Timely seedlings. Seedlings up to 0.5cm can be divided into seedlings in a timely manner, and the first five branches of the seedlings are planted and cultured in groups. The end of March and the first half of the following year can be cultivated. (3) Harvest time. Pacific oyster harvest time should be based on its biological characteristics, environmental conditions of the aquaculture sea area and economic benefits. The typhoon season in the South Bohai Sea is mostly August-October. Therefore, the harvest should be harvested before and after the typhoon season in August. No typhoon annual harvest can be divided into 2 times, the first time in October before the oysters mature gonads, the second harvest in December. Many breeding seasons have no production significance because the growth of oysters is not obvious in the second year of cultivation.
I. Aquaculture areas and their natural conditions are farmed at Guosheng Island and Mazu Bohai District on Lamma Island. The average water depth in the sea area is 2.87m. The muddy sediments have an average annual water temperature of 18.7°C. The monthly maximum water temperature is 27.8. °C (August), the minimum is 9.6°C (February), seawater salinity averages 30.46 年, and the monthly average salinity is 33.07 ‰ (July-August), the monthly minimum salt The degree is 27.07 ‰ (November). The tide is a regular half-day tide with an average tidal range of 3.74 m and a tidal current speed of 0.29 m/s. The currents are mainly affected by the warm currents of Taiwan (black tide branch), the coastal currents of Zhejiang and the runoff from the sea, and the transparency of the water is greater than 2m in summer and autumn. The winter and spring seasons are larger than 1m, and the pH value is generally between 8.05 and 8.40. Seawater is rich in nutrients. The annual average amount of phytoplankton is 4.3x105/m3.
Second, truss settings and breeding equipment
1.ç Set to downstream.
2. Floating rafts are mainly composed of floating stems, floats, anchor stems, and piles (anchors). Floating stems are made of polyethylene ropes and have a length of 60m and a rope diameter of 2.8cm to 3.0cm. The anchor stem adopts the polyethylene rope, the diameter is 2.8cm--3.0cm, the length is 2 times - 3 times of the water depth when the tide is full. Floats are made of glass balls, plastic balls, etc. They are 28cm in diameter, and each floater needs 30 floats. The pile is made of bamboo tube, mixed wood or drop stone with a length of 120cm--150cm and a diameter of 15cm--20cm.
3. Other culture ropes use polyethylene ropes with a diameter of 5mm. The lifting ropes are 1.2m to 1.5m long. Each attachment base (shell) is 15 and each float is hung by 150.
Third, seed sources and transportation
1. The first batch
On December 18, a total of 160 oysters were returned from Luoyuan, Fujian Province, and 100 shells (attached bases) were hoisted. The seeds were attached to shells of oysters, dried and transported for 15 hours, and seawater was sprayed on the way. After being held in shrimp ponds for a period of time, they were transported to Nanxun holding on January 11 of the following year.
2. The second batch of mid-November the following year, the introduction of oyster seedlings from Lianjiang, shipping, because the seedlings have been completed and directly into the breeding period, the seed size is like sand size.
Fourth, seedlings and seedlings to cultivate the seedlings on April 18 of the following year began to split seedlings, each hanging 15 shells, interval 10cm or so, after inspection, each shell with seedlings 3 - 4 seedlings, seedlings rope Using a nylon cord with a diameter of 0.5 cm, the second seedling was performed in late May.
V. Routine management First, the sludge should be washed in a timely manner during the seedling period so as not to suffocate the seedlings. The second is to remove the attachments of the oyster surface in time. During June-July, as the water temperature rises, there are more oyster attachments and poor water flow, which hinders the oyster's filter food, and competes with oysters for bait, which affects the growth of oysters, and should be handled with care when washing. Seedlings fall off; Thirdly, to prevent winding and falling off of hanging ropes between cranes and hoists, timely conduct safety inspections on cables, floats, stakes, and seedlings, etc., and find that problems are solved in time. Fourth, during the growth of oysters, timely seedlings or buoyancy should be added to reduce the tolerance of the oysters.
Sixth, the test results The first batch of seedlings were cultured until August 16 of the following year, the shell height was 6.34cm, and the body weight was 31.0g. By September 25, the shell height was 7.35cm and the weight was 64g. On August 28, the height of the shell was measured 8.87 cm and the body weight was 69.35 g. Pacific oysters continue to breed for one year after reaching product specifications. Individuals do not gain weight. It can be seen that there is no production significance for continuous breeding for one year. The growth of Pacific oysters in the South Bohai Sea is from April to November, and the individual grows fastest from June to September.
The second batch of seedlings was cultured until August 27 of the third year. The height of the shell was measured to be 7.26cm and the weight was 64g. Generally, the weight per heave was 3.0kg--3.5kg.
Seventh, summary and discussion
1. The test results show that the longline cultivation of Pacific oysters in the South Bohai Sea is feasible, with the advantages of rapid growth, high yield, high meat yield, short breeding cycle, and avoidance of typhoons. After aquaculture in recent years, the production capacity and production potential of Pacific oysters in the South Bohai Sea area have been ascertained. The yield per mu can reach 5 tons, and the seedlings can be planted in the fall. The product can be sold in summer for 31g in the summer and before the typhoon season. Can be harvested.
2. Several factors affecting production: (1) Time of seedlings. When the seedlings are subcultured twice, the seedlings will not affect the growth of the oysters when they are unripe, and the growth environment of the oysters will be improved after the seedlings are separated, which will increase the aquaculture production. (2) Attachments. Many attachments were found in the breeding process, such as indirect damage to oysters by sea anemones, barnacles, bryozoans, and lime worms. They competed with oysters to compete for sessile roots, affecting the fixation and growth of oysters, as well as directing of species such as crabs and crabs. Harm oysters. In production, sun exposure, fresh water bathing, or adjustment of hanging water layers or inversion can be used for control purposes. (3) Seed quality. Seed quality directly affects the production of oysters. Seed selection first checks whether each shell is attached to the seedlings in a uniform manner. Generally, each shell contains 10 or more seeds to account for 90% of the seedlings, and secondly, it is necessary to gently touch the seedlings to see if they fall off. The robust seedlings are not easy to fall off, and the color is dark brown, and the seedlings are easy to fall off and mostly white. (4) Time for seedlings to be released.
3. The study of Pacific oyster culture mode in the South Bohai Sea Region: (1) Time of advancement. In the autumn, the planting time is October-November, and the seedlings can be transplanted as soon as possible after the typhoon season to extend the growth period of the seedlings in the South Bohai Sea area. (2) Timely seedlings. Seedlings up to 0.5cm can be divided into seedlings in a timely manner, and the first five branches of the seedlings are planted and cultured in groups. The end of March and the first half of the following year can be cultivated. (3) Harvest time. Pacific oyster harvest time should be based on its biological characteristics, environmental conditions of the aquaculture sea area and economic benefits. The typhoon season in the South Bohai Sea is mostly August-October. Therefore, the harvest should be harvested before and after the typhoon season in August. No typhoon annual harvest can be divided into 2 times, the first time in October before the oysters mature gonads, the second harvest in December. Many breeding seasons have no production significance because the growth of oysters is not obvious in the second year of cultivation.
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