Venerupis variegata, commonly known as flower pods (northern seaweed), belongs to Veneridae. Because of its fast growth, strong adaptability and delicious meat, it is an important breed for traditional shellfish culture. One, China's north and south coasts have a large area of ​​culture. Fuqing City, Fujian Province, has been growing seedlings since the early 1980s, and the seedling raising technology has gradually matured. It has now become the main producing area of ​​China's variegated clam seedlings. In recent years, due to the large number of young farmers in Shandong, Liaoning and other regions purchasing seedlings, there is a shortage of seedlings and a rise in the price of seedlings. The general farmers have promoted the production technology of seedlings of variegated color, the radiation of producing areas, and the price trend of shellfish seedlings. Both expressed great concern.
In order to prolong the spawning period, increase the spawning rate, increase the spawning amount and the number of spawning batches, it is a prerequisite for obtaining a large number of mature eggs. Based on the author's accumulated experience in production, this article describes in detail the application of pro-bain boosting cultivation and different methods of oxytocin production.
I. Environmental Conditions The area of ​​the Grand Beach in the headland ranges from hundreds of acres to several thousand acres. Both the size and the tide can enter the water, sandy bottom or sand and mud bottom, water depth 1.5m--2.0m, seawater specific gravity 1.019. --1.022. The spawning period of the variegated oyster clams in the coastal areas of Fujian is from mid-September to November each year, and it is required that clear pools start to swell in July.
Second, pro-bei cultivation
1. The pro-betting area and the amount of parental pro-family pro-family zone are usually set in nursery granules, and it is better to approach the intake gate. The area of ​​the pro-betting area is determined by the amount of pro-shellfish. The pro-scallop area is stocked with probiotics of 20 lb./mu - 30 lb./mu, and the pro-shell 50kg/mu - 75kg/mu is required. Prior to the transfer of pro-shellfish, the pro-beit area should be covered with fine sand with a sand thickness of about 15cm.
2. Parent-to-parent transport
(1) Pro-shellfish selection Starting from mid-September, a survey was conducted on pro-scallops in different culture areas to compare the prolific sex, sex ratio, sperm-egg quality, and environment of the breeding area. It is generally preferable to use pro-bells that are unobstructed, rich in feed, and low-middle-tide, and try to avoid choosing pro-shellfish from a single sea area or a single seed source. According to observations in recent years, there was no significant difference in the number of eggs laid per unit, the fertilization rate, and the survival rate of larvae between the first instar larvae and the second instar larvae and third instar larvae.
(2) Transferring time to determine the profuse glands in the sea area to avoid miscarriage in the sea area. Generally around August 15th of the lunar calendar each year, the water temperature is around 27°C, and the profuse gonads can reach 60%--80% fullness. Parents can return to the site for a simple stimulus to spawn. In a sea area where the tide is too fast, when pro-occlusion glands are 30% to 40% full, they may be miscarried in the sea area. Parents should be re-adjusted in advance. After about 20 days of intensive intensive care, the gonad plumpness can range from 30% to 40. % increases to 80% - 90%.
3. The food-feeding pro-shellfish is mainly fed with natural phytoplankton and benthic diatoms. The pro-beads are transferred back to the first 3 days - 5 days, and the beach is about 50cm into the water, and the organic manure such as decomposed human excrement and chicken manure is used. The dosage is 15kg/mu - 20kg/mu, generally 3 days after fertilization - - There will be a peak of phytoplankton in 4 days. After parent stocking the big beach, fresh seawater was added daily to a water depth of 80cm, and inorganic fertilizers were used instead. The method of “a small amount and frequent application†was adopted to control the transparency of the water body at 50cm--80cm. If the transparency of the water exceeds 80cm, soymilk can be applied to the pro-betting area. The amount of soybean is 0.5kg/mu - 1.0kg/mu.
Third, oxytocin method Variety Ruditapes from mid-September to mid-November a breeding season can be spawned 3 batches - 4 batches. The gonad maturation of pro-shellfish in the cold air, the water temperature suddenly dropped, and sometimes emit natural eggs, but in most cases still need artificial induction.
1. The dry and irritating method of pro-beads was transferred back to the same day, and the pro-Beiyin dry air was blown for about 15 hours (the time was calculated from the pro-Bei wash from the sea area). This method has a high yield of almost 100%, and the incubation period is 3 hours - 12 hours.
2. Variable-temperature water-stimulating method reduces the water level in the pro-betting zone to about 5cm. From the afternoon to 14 o'clock, it warms up with sunlight for 3 hours - 5 hours, drains the water, cools the shade for 5 hours - 8 hours, and stimulates the water for 2 hours - 3 hour. This method produces 50% - 80% of incretion, the incubation period is indeterminate, and sperm emission sometimes occurs after 24 hours of production.
3. Sexual induction method A small amount of progenitors matured in the gonads (about 1 inoculum total) were crushed and placed directly on the pro-betting area with a mesh bag. Using this method alone, oxytocin is difficult to succeed, but combined with temperature-changing water-stimulating method can increase the productivity.
4. The ammonium bicarbonate stimulation method will reduce the water level in the pro-betting area to about 5cm, and dry sodium bicarbonate in the pro-beta area at an amount of 1.5kg/mu - 2.5kg/mu. After 2 hours, the water will stimulate for 2 hours - 3 hour. This method has a high productivity, but there is a certain risk. If the production is not successful, it can sometimes lead to a large number of pro-shellfish deaths and should be used with caution.
Fourth, common problems and countermeasures
1. Pro-Bacillus discharges metabolites continuously during the cultivation process, resulting in gradual aging of water in pro-betting areas. It usually begins about 1 month after the start of seedling development, and pro-benthic areas begin to turn black and even stink. Although the profuse gonads have good plumpness, but the eggs are poor and the sperm lacks vitality, the oxytocin production methods using the above-mentioned oxytocin production methods are difficult to achieve success, or they can spawn and release sperm, but the fertilization rate is low and the larvae are not normally developed. Measures should be taken to strictly control the pro-beaut intensive nutrient density and the amount of soybean milk used.
2. Years of inbreeding have led to a drop in parent shell germplasm. According to reports from various nursery schools, the number of D-shaped larvae that could produce 500 million--8 million larvae per benevolent population in the 1980s, and 300-400 million D-type larvae per kinship in 1998-2002, and the nursery has to Relies on increasing the amount of pro-shellfish to make up, thus increasing the cost of nursery. The countermeasures are to improve pro-fate plumpness and maturity, or to use pro-scallops of different seedlings from different regions.
3. Although the pro-betting area sands provide a good habitat for pro-scallops, it also becomes the attachment base of the prosortium, which can cause pro-shellfish death. Should promptly remove the water in the Enteromorpha, pay attention to phytoplankton culture, control the transparency of the water to inhibit the growth of Brassica.
Chen Yanfeng Fuzhou Institute of Fisheries Science, Fujian Province 350005
In order to prolong the spawning period, increase the spawning rate, increase the spawning amount and the number of spawning batches, it is a prerequisite for obtaining a large number of mature eggs. Based on the author's accumulated experience in production, this article describes in detail the application of pro-bain boosting cultivation and different methods of oxytocin production.
I. Environmental Conditions The area of ​​the Grand Beach in the headland ranges from hundreds of acres to several thousand acres. Both the size and the tide can enter the water, sandy bottom or sand and mud bottom, water depth 1.5m--2.0m, seawater specific gravity 1.019. --1.022. The spawning period of the variegated oyster clams in the coastal areas of Fujian is from mid-September to November each year, and it is required that clear pools start to swell in July.
Second, pro-bei cultivation
1. The pro-betting area and the amount of parental pro-family pro-family zone are usually set in nursery granules, and it is better to approach the intake gate. The area of ​​the pro-betting area is determined by the amount of pro-shellfish. The pro-scallop area is stocked with probiotics of 20 lb./mu - 30 lb./mu, and the pro-shell 50kg/mu - 75kg/mu is required. Prior to the transfer of pro-shellfish, the pro-beit area should be covered with fine sand with a sand thickness of about 15cm.
2. Parent-to-parent transport
(1) Pro-shellfish selection Starting from mid-September, a survey was conducted on pro-scallops in different culture areas to compare the prolific sex, sex ratio, sperm-egg quality, and environment of the breeding area. It is generally preferable to use pro-bells that are unobstructed, rich in feed, and low-middle-tide, and try to avoid choosing pro-shellfish from a single sea area or a single seed source. According to observations in recent years, there was no significant difference in the number of eggs laid per unit, the fertilization rate, and the survival rate of larvae between the first instar larvae and the second instar larvae and third instar larvae.
(2) Transferring time to determine the profuse glands in the sea area to avoid miscarriage in the sea area. Generally around August 15th of the lunar calendar each year, the water temperature is around 27°C, and the profuse gonads can reach 60%--80% fullness. Parents can return to the site for a simple stimulus to spawn. In a sea area where the tide is too fast, when pro-occlusion glands are 30% to 40% full, they may be miscarried in the sea area. Parents should be re-adjusted in advance. After about 20 days of intensive intensive care, the gonad plumpness can range from 30% to 40. % increases to 80% - 90%.
3. The food-feeding pro-shellfish is mainly fed with natural phytoplankton and benthic diatoms. The pro-beads are transferred back to the first 3 days - 5 days, and the beach is about 50cm into the water, and the organic manure such as decomposed human excrement and chicken manure is used. The dosage is 15kg/mu - 20kg/mu, generally 3 days after fertilization - - There will be a peak of phytoplankton in 4 days. After parent stocking the big beach, fresh seawater was added daily to a water depth of 80cm, and inorganic fertilizers were used instead. The method of “a small amount and frequent application†was adopted to control the transparency of the water body at 50cm--80cm. If the transparency of the water exceeds 80cm, soymilk can be applied to the pro-betting area. The amount of soybean is 0.5kg/mu - 1.0kg/mu.
Third, oxytocin method Variety Ruditapes from mid-September to mid-November a breeding season can be spawned 3 batches - 4 batches. The gonad maturation of pro-shellfish in the cold air, the water temperature suddenly dropped, and sometimes emit natural eggs, but in most cases still need artificial induction.
1. The dry and irritating method of pro-beads was transferred back to the same day, and the pro-Beiyin dry air was blown for about 15 hours (the time was calculated from the pro-Bei wash from the sea area). This method has a high yield of almost 100%, and the incubation period is 3 hours - 12 hours.
2. Variable-temperature water-stimulating method reduces the water level in the pro-betting zone to about 5cm. From the afternoon to 14 o'clock, it warms up with sunlight for 3 hours - 5 hours, drains the water, cools the shade for 5 hours - 8 hours, and stimulates the water for 2 hours - 3 hour. This method produces 50% - 80% of incretion, the incubation period is indeterminate, and sperm emission sometimes occurs after 24 hours of production.
3. Sexual induction method A small amount of progenitors matured in the gonads (about 1 inoculum total) were crushed and placed directly on the pro-betting area with a mesh bag. Using this method alone, oxytocin is difficult to succeed, but combined with temperature-changing water-stimulating method can increase the productivity.
4. The ammonium bicarbonate stimulation method will reduce the water level in the pro-betting area to about 5cm, and dry sodium bicarbonate in the pro-beta area at an amount of 1.5kg/mu - 2.5kg/mu. After 2 hours, the water will stimulate for 2 hours - 3 hour. This method has a high productivity, but there is a certain risk. If the production is not successful, it can sometimes lead to a large number of pro-shellfish deaths and should be used with caution.
Fourth, common problems and countermeasures
1. Pro-Bacillus discharges metabolites continuously during the cultivation process, resulting in gradual aging of water in pro-betting areas. It usually begins about 1 month after the start of seedling development, and pro-benthic areas begin to turn black and even stink. Although the profuse gonads have good plumpness, but the eggs are poor and the sperm lacks vitality, the oxytocin production methods using the above-mentioned oxytocin production methods are difficult to achieve success, or they can spawn and release sperm, but the fertilization rate is low and the larvae are not normally developed. Measures should be taken to strictly control the pro-beaut intensive nutrient density and the amount of soybean milk used.
2. Years of inbreeding have led to a drop in parent shell germplasm. According to reports from various nursery schools, the number of D-shaped larvae that could produce 500 million--8 million larvae per benevolent population in the 1980s, and 300-400 million D-type larvae per kinship in 1998-2002, and the nursery has to Relies on increasing the amount of pro-shellfish to make up, thus increasing the cost of nursery. The countermeasures are to improve pro-fate plumpness and maturity, or to use pro-scallops of different seedlings from different regions.
3. Although the pro-betting area sands provide a good habitat for pro-scallops, it also becomes the attachment base of the prosortium, which can cause pro-shellfish death. Should promptly remove the water in the Enteromorpha, pay attention to phytoplankton culture, control the transparency of the water to inhibit the growth of Brassica.
Chen Yanfeng Fuzhou Institute of Fisheries Science, Fujian Province 350005