First, broodstock selection and cultivation of broodstock can be artificially propagated or captured from natural sea areas. Females choose to weigh 0.5 kg to 1 kg, abdomen enlargement and soft; males choose to weigh more than 1.5 kilograms, clearing the abdomen can flow out of semen. Male and female broodstock with a ratio of 1:1 to 1:3. Grouper is a female prehybrid hermaphrodite fish, and its 6th instar was transformed into a male fish. In recent years, due to overfishing, the sex ratio of polyandroidism is less in the reproductive groups of natural sea areas, and it is cultivated under cultivation conditions. Older male individuals have long broodstock and are expensive. Therefore, the problem with broodstock selection is that it is not easy for males to get mature gonads. In order to solve the problem of male broodstock deficiency in artificial propagation, exogenous sex hormone 17α-methyl testosterone can be used to induce hermaphrodite red-spotted grouper, and early 3rd to 4th instar can be used to transform females into male broodstock with reproductive function, and 17α- Methyltestosterone can not only inhibit yolk production, but also affect oocyte proliferation and differentiation. For the 2nd to 4th instar fish fed 50 days of baits, each dose of about 5 mg/kg body weight (cumulative volume 241.3 mg/kg body weight), can make sexual conversion of male bred fish flow rate of 93.5%, insemination rate reached 81.1%, normal embryonic development. In order to solve the problem of “sex change†caused by uneven bait intake due to uneven intake of male hormone baits and daily feeding and time-consuming issues, males that implant 17α-methyl testosterone into fish can also be used. Hormone implantation to induce early "sex changes" in groupers. 17α-methyl testosterone can be implanted into mature red-spotted grouper females aged 3 to 7 at one time. After 50 days to 90 days, females are transformed into male fish, making the grouper “sex changeâ€. The process is 5 to 6 years earlier. Fertilized eggs obtained by using their semen have a fertilization rate of 73% and a hatching rate of 97%. The larvae develop normally and can achieve artificial breeding purposes. Under the same treatment conditions, the "sex transition" of female senior fish is shorter than that of younger fish, and it is easier to obtain modified male fish. Therefore, in the artificial reproduction should choose the older, individual larger female for degeneration treatment, the effect is better.
In order to solve the relatively rare problem of artificially breeding neutral males, cryopreservation can also be used to preserve the semen. After 2 months of cryopreservation in liquid nitrogen tanks, the semen still has the vitality equivalent to fresh essence without affecting artificial reproduction. Effect. The effect of artificial reproduction largely depends on the maturity of the gonad gonads, so it is important to strengthen broodstock development and promote gonad development before inducing spawning. Reserve or hold grouper broodstock in the indoor concrete pool, artificially strengthen the cultivation, change the water and suck the dirt daily, the broodstock can spawn and fertilize naturally without hormone production, and can obtain high-quality fertilized eggs.
Second, the oxytocin selected female broodstock, with a thin plastic tube or egg dig device from the production of the egg hole inserted about 3 cm to 5 cm deep aspirate the eggs, placed on a slide, observe the degree of maturity under the microscope, if the egg easy Segregation, egg yellow, plump, egg diameter 0.3 mm to 0.5 mm, plus transparent fixative solution after the nucleus has been biased towards the animal pole, the maturity is better. Male brooders gently press on the abdomen with a little bit of semen flowing well. Grouper semen volume is small, do not squeeze too much when checking male maturity. There are 4 types of coproducers: the mixture of salmon pituitary, human chorionic gonadotropin, luteinizing hormone releasing hormone analogues, and LRH-A+PG.
Female fish used PG 10 mg/kg body weight to 12 mg/kg body weight or LRH-A 60 micrograms/kg. The above dose is generally divided into two thoracic injections, the first injection volume accounts for 2/3 of the total, and the interval between the two is about 24 hours at a water temperature of 25°C to 26°C. Male broodstock is injected at half the dose of females, both at the same time as the female's second injection. The water for injection is a 0.6% sodium chloride solution, and the oxytocide is dissolved or made into a suspension. The injection volume is 1 ml to 2 ml for each broodstock.
Third, artificial insemination and natural spawning Fertilized red grouper artificial insemination should adopt dry insemination. The broodstock can be spawned 10 to 13 hours after the injection of the second oxytocic agent. The abdomen of the female fish is gently pressed from top to bottom, and the mature fish eggs are squeezed into the disinfected white porcelain bowl, and repeated 5 to 6 times. The broodstock can be gently returned to the broodstock tank. Immediately thereafter, the male semen was squeezed into the egg pile of a white porcelain bowl in the same manner. Grouper semen rarely, even squeezed 5 to 6 times, but also a total of 1 ml to 2 ml, but it is enough. After the final squeeze is completed, the eggs and semen in the bowl are mixed with clean feathers soaked in sterile seawater. After about 1 minute to 2 minutes, a small amount of disinfected seawater is added. After stirring for 5 minutes, it is poured on the sterilized small ones. In the washbasin, add sterile seawater and stir gently and let stand for a while. All fertilized eggs float in the upper and middle layers of water, and dead eggs or unfertilized eggs precipitate at the bottom. Wash the fertilized eggs with sterile seawater, remove excess sperm to avoid multiple sperm fertilization, and then transfer the fertilized eggs to the incubator.
When artificial insemination, direct sunlight should be avoided to avoid killing sperm. As the grouper spawns fish spawned in batches, there are several reproductive characteristics of spawning.
For the broodstock to create environmental conditions for natural spawning and fertilization in the spawning pool, it is possible to avoid the disadvantages of over-ripening or under-mature eggs that often occur during artificial insemination, as well as to reduce broodstock caused by fishing and squeezing out eggs and squeezing semen. s damage. Therefore, it is also possible to strengthen the method of culturing grouper broodstock, to promote broodstock secretion of hormones, without spawning oxytocin and natural spawning and fertilization, so as to obtain a high quality fertilized eggs, improve the survival rate of larvae, reduce the deformity rate. Natural spawning is better than artificial insemination. Suitable spawning temperature 25 °C ~ 27 °C, sea water salinity 32 ~ 35, pH 7.8 ~ 8.5, spawning pond area of ​​20 square meters, water depth of about 1.5 meters, shade above the pool shading, water flow 40 liters / minute ~ 50 liters/minute.
Fourth, hatching groupers produce floating eggs, hatching should be carried out in the ring incubator or hatching tank. The egg density during hatching was 50 eggs/liter seawater to 100 eggs/liter seawater, and the water velocity was such that the eggs or larvae could float. The hatchery water must be fresh and must be sterilized by sand filtration and ultraviolet light. The water temperature is maintained at about 25°C, and the salinity is from 30 to 33, and remains stable. During the incubation process, moderate inflation is required, and if the aeration is too large or too small, it is not good, and the dissolved oxygen in the sea is maintained at 5 mg/L or more. During the incubation, remove dead eggs as much as possible to make the waterproof material worse. Red-spotted grouper and blue grouper eggs In the above conditions, fry can be hatched after 24 hours from fertilization.
In order to solve the relatively rare problem of artificially breeding neutral males, cryopreservation can also be used to preserve the semen. After 2 months of cryopreservation in liquid nitrogen tanks, the semen still has the vitality equivalent to fresh essence without affecting artificial reproduction. Effect. The effect of artificial reproduction largely depends on the maturity of the gonad gonads, so it is important to strengthen broodstock development and promote gonad development before inducing spawning. Reserve or hold grouper broodstock in the indoor concrete pool, artificially strengthen the cultivation, change the water and suck the dirt daily, the broodstock can spawn and fertilize naturally without hormone production, and can obtain high-quality fertilized eggs.
Second, the oxytocin selected female broodstock, with a thin plastic tube or egg dig device from the production of the egg hole inserted about 3 cm to 5 cm deep aspirate the eggs, placed on a slide, observe the degree of maturity under the microscope, if the egg easy Segregation, egg yellow, plump, egg diameter 0.3 mm to 0.5 mm, plus transparent fixative solution after the nucleus has been biased towards the animal pole, the maturity is better. Male brooders gently press on the abdomen with a little bit of semen flowing well. Grouper semen volume is small, do not squeeze too much when checking male maturity. There are 4 types of coproducers: the mixture of salmon pituitary, human chorionic gonadotropin, luteinizing hormone releasing hormone analogues, and LRH-A+PG.
Female fish used PG 10 mg/kg body weight to 12 mg/kg body weight or LRH-A 60 micrograms/kg. The above dose is generally divided into two thoracic injections, the first injection volume accounts for 2/3 of the total, and the interval between the two is about 24 hours at a water temperature of 25°C to 26°C. Male broodstock is injected at half the dose of females, both at the same time as the female's second injection. The water for injection is a 0.6% sodium chloride solution, and the oxytocide is dissolved or made into a suspension. The injection volume is 1 ml to 2 ml for each broodstock.
Third, artificial insemination and natural spawning Fertilized red grouper artificial insemination should adopt dry insemination. The broodstock can be spawned 10 to 13 hours after the injection of the second oxytocic agent. The abdomen of the female fish is gently pressed from top to bottom, and the mature fish eggs are squeezed into the disinfected white porcelain bowl, and repeated 5 to 6 times. The broodstock can be gently returned to the broodstock tank. Immediately thereafter, the male semen was squeezed into the egg pile of a white porcelain bowl in the same manner. Grouper semen rarely, even squeezed 5 to 6 times, but also a total of 1 ml to 2 ml, but it is enough. After the final squeeze is completed, the eggs and semen in the bowl are mixed with clean feathers soaked in sterile seawater. After about 1 minute to 2 minutes, a small amount of disinfected seawater is added. After stirring for 5 minutes, it is poured on the sterilized small ones. In the washbasin, add sterile seawater and stir gently and let stand for a while. All fertilized eggs float in the upper and middle layers of water, and dead eggs or unfertilized eggs precipitate at the bottom. Wash the fertilized eggs with sterile seawater, remove excess sperm to avoid multiple sperm fertilization, and then transfer the fertilized eggs to the incubator.
When artificial insemination, direct sunlight should be avoided to avoid killing sperm. As the grouper spawns fish spawned in batches, there are several reproductive characteristics of spawning.
For the broodstock to create environmental conditions for natural spawning and fertilization in the spawning pool, it is possible to avoid the disadvantages of over-ripening or under-mature eggs that often occur during artificial insemination, as well as to reduce broodstock caused by fishing and squeezing out eggs and squeezing semen. s damage. Therefore, it is also possible to strengthen the method of culturing grouper broodstock, to promote broodstock secretion of hormones, without spawning oxytocin and natural spawning and fertilization, so as to obtain a high quality fertilized eggs, improve the survival rate of larvae, reduce the deformity rate. Natural spawning is better than artificial insemination. Suitable spawning temperature 25 °C ~ 27 °C, sea water salinity 32 ~ 35, pH 7.8 ~ 8.5, spawning pond area of ​​20 square meters, water depth of about 1.5 meters, shade above the pool shading, water flow 40 liters / minute ~ 50 liters/minute.
Fourth, hatching groupers produce floating eggs, hatching should be carried out in the ring incubator or hatching tank. The egg density during hatching was 50 eggs/liter seawater to 100 eggs/liter seawater, and the water velocity was such that the eggs or larvae could float. The hatchery water must be fresh and must be sterilized by sand filtration and ultraviolet light. The water temperature is maintained at about 25°C, and the salinity is from 30 to 33, and remains stable. During the incubation process, moderate inflation is required, and if the aeration is too large or too small, it is not good, and the dissolved oxygen in the sea is maintained at 5 mg/L or more. During the incubation, remove dead eggs as much as possible to make the waterproof material worse. Red-spotted grouper and blue grouper eggs In the above conditions, fry can be hatched after 24 hours from fertilization.
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