Rhopilema esculenta is a large edible jellyfish. In recent years, due to the continuous expansion of sea bream breeding, the demand for sea lice seedlings has also increased, and artificial seedlings are particularly important. This article briefly introduces the technical points of artificial breeding of sea lice, for reference by the majority of production units.
I. Natural sea catching The procreation of the northern coast sea bream during the reproductive period is from mid-August to mid-October, and during a reproductive season there are 2 to 3 peak discharges of gonads. In production, pro-spawning should be carried out during the first maturation period of the natural population, that is, from the end of August to the beginning of September. Intimate request umbrella diameter is above 30cm, male and female identification can be used to insert from the genital mound into the scorpion, remove small gonads to enlarge 20 times -40 times observation, the egg presents as spherical particles of different sizes, is fine in the appearance of irregular kidney shape, When the color of the gonad changes from brown to milky, the gland becomes mature, which is about to be discharged. Generally, the indigestive male and female individuals are cultured in separate ponds. The amount of oxygen consumed by inbreeding is approximately 3000 mg/day to 4000 mg/day at 20°C-25°C. If the water is changed every 24 hours during stocking, it is estimated. The body of water occupied by a brood should not be less than 2m3, and the greater the density of intimacy, the greater the number of water changes.
Second, spawning and hatching
1. Water storage and water treatment 1 day before nursery, brush the pool clean and inject fresh seawater as hatching pool. If the nursery room is located near Neiwan or near the city, 4X1O-6mOl/L-8x10-6mOl/L of EDTA (sodium ethylenediaminetetraacetate) can be added to the seawater to play a role in complexing heavy metal ions, so as to facilitate the improvement of hatching. rate.
2. The timing of spawning and ejaculation in males and females is at dawn. Therefore, parents should be moved from the reservoir to hatching pool between 5:00 and 6:00 am. The spawning time can last from 1 hour to 2 hours. Day 1 - Day 2 was less, then increased sharply until the 7th day - the 10th day was the peak period, and then drastically decreased. The proportion of males and females with intimacy is 2-3:1, and the density is 2/m3-3/m3. Increasing the density is conducive to mutual induction between male and female individuals, and a large number of fertilized eggs can be collected. Most of the prostitutes died after their delivery.
3. After 1 hour of sampling by humans, samples were taken from the bottom of the pool and the cleavage of the fertilized eggs was observed under a microscope. Samples were observed every 20 minutes to 30 minutes until a large number of cleaved eggs were found. Fertilized eggs or unfertilized eggs disintegrate.
4, remove the insemination and fertilization egg cleavage from the 16-cell period began to form the blastocyst cavity, embryo larvae gradually float from the bottom of the pool, and in the water was semi-uplift state, therefore, should be in the fertilized egg cleavage for about 3 hours and will The relatives were removed and re-used for spawning the next day. After 30 minutes of standing pool water, use a rubber hose to siphon and discharge the upper pool water. Generally the water level drops to about 30cm. When draining, the hose port on the inner side of the hatching tank should be upward, so that the pool water should not be agitated as much as possible, and it is better to be completed within one hour to avoid a large loss of fertilized eggs. After the drainage is completed, appropriate amount of isothermal seawater should be added every day to keep the water fresh.
5. Hatching fertilized eggs are hatched as pelagic larvae after 6 hours to 8 hours, and quantified using the volume method. Normal hatching rate is above 80%.
III. Management of metamorphosis and attachment of floating larvae
1. The attachment base is placed in the attachment base within 24 hours. Since the floating larvae mostly move obliquely upward at the front end, the attachment base should be parallel to the water surface. When the floating larvae metamorphose into larval larvae, most of the larvae attach to the underside of the attachment base, and the majority of larval larvae have upwardly shanked upwards and appear inverted.
2. It is advisable to add fresh seawater and seawater in order to submerge the attachment base. After that, add appropriate amount of fresh seawater every 2 days and fill it up 5 times (10 days), ie change the water within 10 days to prevent floating larvae or not yet The attached pods lost a great deal.
3. Repeated release of floating larvae The floating larvae have a metamorphosis attachment density of 3 million/m3 to 5 million/m3. The hatched larvae can be quantified and then put into the hatching pool with the seedlings attached.
IV. Cultivation and management of zoea
1. The main techniques for the cultivation of zoea larvae include timely feeding and changing of water. The early zoea had the best effect on shellfish larvae and this type of floating larvae as the open bait. The feeding time should be 4 days to 5 days after the seedlings were added, and the feeding should be carried out once a day. More than 5 times the seedling volume; 5 days to 6 days after the development of the medium-sized zoea, Artemia nauplii at the beginning of the feeding period, feeding once every 2 days, and starting 1 hour after feeding and inflating Change the water, change the amount of water for the whole pool of 1/4-1/2; After 8 days -10 days of culture, can be developed into late zoea.
2. Management of the zoea larvae The time for artificially cultivating the juvenile larvae is from September to October in the autumn, and the time for cultivating the cubs is from May to June in the summer of the following year. The interval time is about 7 months, and there is an overwintering stage. During this period, the zoea will undergo full-fetal cyst reproduction, replicating the new zoea. After the larvae have been quantified, they should be poured into the pool and replaced with water. Generally, the following four management measures are taken:
First, control the luminosity. The pool is covered with a black cloth to keep the dark or weak light in the pool, prevent the growth of the algae and the like on the seedlings, so as to increase the survival rate of the juvenile larvae, and also facilitate the reproduction of the pods.
Second, keep it cool. Zocal larvae adapt to low temperature life, below 10 °C, above the freezing point is appropriate, long-term living at 1O °C -15 °C conditions, the number of deformed individuals increased, so the jellyfish spawning can not be too early, should be in the pool water temperature dropped to 10 °C the following. In the winter, there should be thermal insulation in the room to keep the pool water from freezing. When the indoor water temperature in spring exceeds 10°C, cooling measures should be taken or the number of water changes should be increased so that the indoor water temperature approaches the natural sea temperature until the natural sea area temperature rises to 13°C-15°C.
Third, timely feeding. Artemia nauplii as bait, depending on the water temperature depending on the number of feeding, generally below 5 °C can not be fed or fed once a week for 4 weeks, 6 °C -10 °C when fed once a week, 11 °C-15 Feed 2 times per week at °C, feeding 10 to 20 times the amount of zoea. The juvenile larvae are orange after satiation and pale when they are hungry. Therefore, the number of feedings and feeding amount can be increased or decreased according to the depth of the color of the juvenile larvae. If there is an obvious Artemia in the water after feeding for 1 hour, The distribution of larvae can be regarded as feeding too much; fourth, change the water timely. Below 10°C, the dissolved oxygen content at the asphyxiation point is 0.1mg/L, the safe concentration of ammoniacal nitrogen is 1.Omg/L, and the water change is usually 1/3 to 1/2 after each feed, and the siphon method is used. At the bottom of the pool, the seawater containing sediment is sucked out, and the same amount of fresh seawater is added.
Fifth, the cultivation and management of dish larvae
1. Cultivation of dish-shaped juveniles The juvenile must undergo transverse fissure to produce jellyfish-type dish-shaped juveniles. The occurrence of transverse fissure in the zoea larvae is mainly constrained by water temperature conditions. When the natural water temperature rises to 13°C-15°C, horizontal temperature control can be used to induce transverse fissure reproduction. At 22°C, the zoea larvae can reproduce their first transverse fissure within 2 weeks. The developmental time for the formation of larval larvae ranges from 1 day to 2 days, and a large number of larvae or pups can be cultivated in a short period of time. Meet the need to concentrate the time to release the breeding or breeding. Photometry and nutrition also have effects on transverse fissure reproduction. Therefore, after the wintering of the braided larvae, the dark conditions should be removed and cultured under indoor natural light (18001x-24001x). In addition, sufficient attention should be paid to the supply of food organisms during the period from the wintering of the zoea to the occurrence of transverse fission.
2. Management of dished larvae Newly born dished larvae are colorless and transparent, with a diameter of 2mm-4mm, and at a temperature of 18°C-22°C for 7 days to 10 days with a radius of about 10mm, they are medium-sized dished larvae and young larvae. 15 days to 20 days radius of about 20mm for the pups. In the cultivation process of jellyfish jellyfish, it is important to keep the water quality fresh. The lower limit of dissolved oxygen in the water is 2.0 mg/L, the upper limit of ammonia nitrogen concentration is 1.5 mg/L, and the pH range is 7.5-8.5. Number of feedings: dish larvae 2 times/day -3 times/day, juvenile larvae 3 times/day - 4 times/day, pups 4 times/day -5 times/day. Each feeding amount was calculated as Artemia nauplii, approximately 1:10-20 for juveniles, 1:100-200 for juveniles, and 1:500-1000 for juveniles. The larvae are changed daily 1 time, 1/3-1/2 times each day; the larvae change water twice a day, each time 1/3-1/2. The micro-inflating method is generally adopted. Under artificially controlled conditions, the survival rate of the dish-like larvae to pups can reach 70% or more.
6. When the number of dish-shaped larvae reaches 20,000/m3 or more in the seedling nursery pool, the attachment base can be moved into an empty nursery pond so that the zoea can continue to disperse the dish-shaped larvae. When the larval part of the dish grows and develops into young cubs, it is no longer inflated. Therefore, it is difficult for the dish-shaped larvae to be cultured in high density, and the seedlings can be emerged using the double-bag emergence method, and the survival rate of the seedlings is above 95%.
I. Natural sea catching The procreation of the northern coast sea bream during the reproductive period is from mid-August to mid-October, and during a reproductive season there are 2 to 3 peak discharges of gonads. In production, pro-spawning should be carried out during the first maturation period of the natural population, that is, from the end of August to the beginning of September. Intimate request umbrella diameter is above 30cm, male and female identification can be used to insert from the genital mound into the scorpion, remove small gonads to enlarge 20 times -40 times observation, the egg presents as spherical particles of different sizes, is fine in the appearance of irregular kidney shape, When the color of the gonad changes from brown to milky, the gland becomes mature, which is about to be discharged. Generally, the indigestive male and female individuals are cultured in separate ponds. The amount of oxygen consumed by inbreeding is approximately 3000 mg/day to 4000 mg/day at 20°C-25°C. If the water is changed every 24 hours during stocking, it is estimated. The body of water occupied by a brood should not be less than 2m3, and the greater the density of intimacy, the greater the number of water changes.
Second, spawning and hatching
1. Water storage and water treatment 1 day before nursery, brush the pool clean and inject fresh seawater as hatching pool. If the nursery room is located near Neiwan or near the city, 4X1O-6mOl/L-8x10-6mOl/L of EDTA (sodium ethylenediaminetetraacetate) can be added to the seawater to play a role in complexing heavy metal ions, so as to facilitate the improvement of hatching. rate.
2. The timing of spawning and ejaculation in males and females is at dawn. Therefore, parents should be moved from the reservoir to hatching pool between 5:00 and 6:00 am. The spawning time can last from 1 hour to 2 hours. Day 1 - Day 2 was less, then increased sharply until the 7th day - the 10th day was the peak period, and then drastically decreased. The proportion of males and females with intimacy is 2-3:1, and the density is 2/m3-3/m3. Increasing the density is conducive to mutual induction between male and female individuals, and a large number of fertilized eggs can be collected. Most of the prostitutes died after their delivery.
3. After 1 hour of sampling by humans, samples were taken from the bottom of the pool and the cleavage of the fertilized eggs was observed under a microscope. Samples were observed every 20 minutes to 30 minutes until a large number of cleaved eggs were found. Fertilized eggs or unfertilized eggs disintegrate.
4, remove the insemination and fertilization egg cleavage from the 16-cell period began to form the blastocyst cavity, embryo larvae gradually float from the bottom of the pool, and in the water was semi-uplift state, therefore, should be in the fertilized egg cleavage for about 3 hours and will The relatives were removed and re-used for spawning the next day. After 30 minutes of standing pool water, use a rubber hose to siphon and discharge the upper pool water. Generally the water level drops to about 30cm. When draining, the hose port on the inner side of the hatching tank should be upward, so that the pool water should not be agitated as much as possible, and it is better to be completed within one hour to avoid a large loss of fertilized eggs. After the drainage is completed, appropriate amount of isothermal seawater should be added every day to keep the water fresh.
5. Hatching fertilized eggs are hatched as pelagic larvae after 6 hours to 8 hours, and quantified using the volume method. Normal hatching rate is above 80%.
III. Management of metamorphosis and attachment of floating larvae
1. The attachment base is placed in the attachment base within 24 hours. Since the floating larvae mostly move obliquely upward at the front end, the attachment base should be parallel to the water surface. When the floating larvae metamorphose into larval larvae, most of the larvae attach to the underside of the attachment base, and the majority of larval larvae have upwardly shanked upwards and appear inverted.
2. It is advisable to add fresh seawater and seawater in order to submerge the attachment base. After that, add appropriate amount of fresh seawater every 2 days and fill it up 5 times (10 days), ie change the water within 10 days to prevent floating larvae or not yet The attached pods lost a great deal.
3. Repeated release of floating larvae The floating larvae have a metamorphosis attachment density of 3 million/m3 to 5 million/m3. The hatched larvae can be quantified and then put into the hatching pool with the seedlings attached.
IV. Cultivation and management of zoea
1. The main techniques for the cultivation of zoea larvae include timely feeding and changing of water. The early zoea had the best effect on shellfish larvae and this type of floating larvae as the open bait. The feeding time should be 4 days to 5 days after the seedlings were added, and the feeding should be carried out once a day. More than 5 times the seedling volume; 5 days to 6 days after the development of the medium-sized zoea, Artemia nauplii at the beginning of the feeding period, feeding once every 2 days, and starting 1 hour after feeding and inflating Change the water, change the amount of water for the whole pool of 1/4-1/2; After 8 days -10 days of culture, can be developed into late zoea.
2. Management of the zoea larvae The time for artificially cultivating the juvenile larvae is from September to October in the autumn, and the time for cultivating the cubs is from May to June in the summer of the following year. The interval time is about 7 months, and there is an overwintering stage. During this period, the zoea will undergo full-fetal cyst reproduction, replicating the new zoea. After the larvae have been quantified, they should be poured into the pool and replaced with water. Generally, the following four management measures are taken:
First, control the luminosity. The pool is covered with a black cloth to keep the dark or weak light in the pool, prevent the growth of the algae and the like on the seedlings, so as to increase the survival rate of the juvenile larvae, and also facilitate the reproduction of the pods.
Second, keep it cool. Zocal larvae adapt to low temperature life, below 10 °C, above the freezing point is appropriate, long-term living at 1O °C -15 °C conditions, the number of deformed individuals increased, so the jellyfish spawning can not be too early, should be in the pool water temperature dropped to 10 °C the following. In the winter, there should be thermal insulation in the room to keep the pool water from freezing. When the indoor water temperature in spring exceeds 10°C, cooling measures should be taken or the number of water changes should be increased so that the indoor water temperature approaches the natural sea temperature until the natural sea area temperature rises to 13°C-15°C.
Third, timely feeding. Artemia nauplii as bait, depending on the water temperature depending on the number of feeding, generally below 5 °C can not be fed or fed once a week for 4 weeks, 6 °C -10 °C when fed once a week, 11 °C-15 Feed 2 times per week at °C, feeding 10 to 20 times the amount of zoea. The juvenile larvae are orange after satiation and pale when they are hungry. Therefore, the number of feedings and feeding amount can be increased or decreased according to the depth of the color of the juvenile larvae. If there is an obvious Artemia in the water after feeding for 1 hour, The distribution of larvae can be regarded as feeding too much; fourth, change the water timely. Below 10°C, the dissolved oxygen content at the asphyxiation point is 0.1mg/L, the safe concentration of ammoniacal nitrogen is 1.Omg/L, and the water change is usually 1/3 to 1/2 after each feed, and the siphon method is used. At the bottom of the pool, the seawater containing sediment is sucked out, and the same amount of fresh seawater is added.
Fifth, the cultivation and management of dish larvae
1. Cultivation of dish-shaped juveniles The juvenile must undergo transverse fissure to produce jellyfish-type dish-shaped juveniles. The occurrence of transverse fissure in the zoea larvae is mainly constrained by water temperature conditions. When the natural water temperature rises to 13°C-15°C, horizontal temperature control can be used to induce transverse fissure reproduction. At 22°C, the zoea larvae can reproduce their first transverse fissure within 2 weeks. The developmental time for the formation of larval larvae ranges from 1 day to 2 days, and a large number of larvae or pups can be cultivated in a short period of time. Meet the need to concentrate the time to release the breeding or breeding. Photometry and nutrition also have effects on transverse fissure reproduction. Therefore, after the wintering of the braided larvae, the dark conditions should be removed and cultured under indoor natural light (18001x-24001x). In addition, sufficient attention should be paid to the supply of food organisms during the period from the wintering of the zoea to the occurrence of transverse fission.
2. Management of dished larvae Newly born dished larvae are colorless and transparent, with a diameter of 2mm-4mm, and at a temperature of 18°C-22°C for 7 days to 10 days with a radius of about 10mm, they are medium-sized dished larvae and young larvae. 15 days to 20 days radius of about 20mm for the pups. In the cultivation process of jellyfish jellyfish, it is important to keep the water quality fresh. The lower limit of dissolved oxygen in the water is 2.0 mg/L, the upper limit of ammonia nitrogen concentration is 1.5 mg/L, and the pH range is 7.5-8.5. Number of feedings: dish larvae 2 times/day -3 times/day, juvenile larvae 3 times/day - 4 times/day, pups 4 times/day -5 times/day. Each feeding amount was calculated as Artemia nauplii, approximately 1:10-20 for juveniles, 1:100-200 for juveniles, and 1:500-1000 for juveniles. The larvae are changed daily 1 time, 1/3-1/2 times each day; the larvae change water twice a day, each time 1/3-1/2. The micro-inflating method is generally adopted. Under artificially controlled conditions, the survival rate of the dish-like larvae to pups can reach 70% or more.
6. When the number of dish-shaped larvae reaches 20,000/m3 or more in the seedling nursery pool, the attachment base can be moved into an empty nursery pond so that the zoea can continue to disperse the dish-shaped larvae. When the larval part of the dish grows and develops into young cubs, it is no longer inflated. Therefore, it is difficult for the dish-shaped larvae to be cultured in high density, and the seedlings can be emerged using the double-bag emergence method, and the survival rate of the seedlings is above 95%.
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