First, artificial insemination
1. Way
(1) Insemination of eggs in the spawning box
The spawning tanks are made of 0.1 to 0.5 liters of plastic or fiberglass tanks. Before spawning, the tanks are filled with seawater of the same temperature as that of the pro-stocking pool or stimulation pool. General spare two spawning boxes, one put female ginseng, put egg, the other put male ginseng, put sperm. See the pros and cons that have signs of spawning and rowing, and fish it to the spawning box in time. Pay attention to the action when fishing, so as not to affect the number of eggs laid. As the eggs of sea cucumbers are sink eggs, it is necessary to continuously stir the water in the tank during the spawning process or micro-inflate to prevent the eggs from affecting their development due to lack of oxygen. While spawning, semen should be added at the same time. Semen should not be added too much. It is best to mix male semen with long male ginseng. The density of eggs in the spawning box should not be too large, generally within 200/ml to 500/ml. After this density is exceeded, the eggs must be transferred to hatching ponds or incubation ponds in time for incubation. This method can artificially control the amount of semen added, without the phenomenon of multiple spermatozoa, which can greatly reduce the malformation rate of the larvae.
(2) In-pool spawning
This method is to allow parents to spawn and evacuate directly in the holding pond or in the breeding pond, and then move the eggs into the hatching pond or hatch in the original pond. General male ginseng discharges prior to female ginseng, allowing male ginseng to discharge for a while in the pool, so that the pool has a certain density of sperm to induce female ginseng to lay eggs. After the female ginseng begins to lay eggs, remove the male ginseng from the pool and allow the female ginseng to spawn and fertilize in the pool. This method is difficult to control the amount of sperm, prone to too much semen caused by high rate of abnormal phenomenon.
2. Factors affecting fertilization
(1) The maturity of mating and the quality of eggs
The maturation degree of the parental ginseng is not mature enough or too mature, and no good quality ovum will be obtained. Therefore, the gonad development of the parent ginseng should be observed in time and the optimal timing of egg collection should be grasped.
(2) Egg density and water temperature
If the density of the eggs is too large, it can easily cause a large amount of eggs to accumulate, lack of oxygen, and affect the normal hatching of eggs. When the water temperature is high, excess sperm accelerates the deterioration of the water and affects the normal hatching of eggs. Researchers at the Liaoning Provincial Institute of Marine Fisheries conducted an artificial insemination experiment with 100,000 sperms per milliliter. At a water temperature of 18°C ​​to 19°C, when the egg density was 130 eggs/ml, the egg could be discharged after its duration. It took 13 hours and neither egg fertilization nor hatching was affected. When the water temperature was between 24°C and 25°C, when the density of storage reached 650 cells/ml, the fertilization rate and hatching rate decreased significantly after the egg was discharged for more than 2 hours. About 3 hours later, the fertilization rate was 62%, but its hatching rate was only 5% and it could hardly hatch. When carrying out productive breeding, the density of eggs should be controlled at about 10 cells/ml to 20 cells/ml, and generally it should be controlled at 10 cells/ml or less. Because the sea cucumber is a heavy egg, such as the depth of the pool is 1 meter, the density of the eggs is 10/ml, then the density after sinking to the bottom of the pool is 1000 eggs/cm2, the density of the eggs in the bottom of the pool. It is quite large. The water temperature during insemination is controlled between 18°C ​​and 22°C, which is consistent with the water temperature of hatching and larval development.
(3) The concentration of sperm
In the production process, sperm concentration is very high. This is more prone to multiple sperm fertilization, will significantly reduce the hatching rate of eggs, increase the malformation rate of larvae and affect the normal development of larvae. Therefore, the concentration of sperm should be controlled as much as possible, and 3 to 5 sperm around each egg can be observed at low magnification. If the sperm concentration is too high, wash it off in time.
Second, hatching
After fertilization in the spawning box, eggs are counted and transferred to hatching tanks or incubation tanks for incubation. When the eggs are inseminated in the pool, after all the eggs sink to the bottom of the pool, the upper and middle layers of water are released, all the parent parameters are thrown out and thrown into other pools, and the egg is quantified after the eggs are washed 2 to 3 times, and then enter the incubation stage. .
1. Method
(1) Incubation in incubation tank
The density of hatching in hatchery tank is relatively large, usually between 100/ml and 200/ml. During hatching, the hatching water or aeration is regularly agitated to keep the eggs in suspension. When the eggs are developed to the blastocyst stage, 0.5 eggs are added. The density of /ml is transferred to a culture pond for further cultivation.
(2) Incubating incubator
The fertilized eggs are transferred into the cultivation tank at a density of 1/ml to 2/ml. Since the density of the eggs is small, they can usually be incubated in still water.
2. Management
(1) Hatching with water temperature
The temperature difference between seawater or newly added seawater and seawater or original hatching water at the time of fertilization should not be too large and should not exceed 3°C, and should generally be within 1°C to 2°C.
(2) Stir or inflate
In order to avoid excessive accumulation of fertilized eggs in the bottom of the pool during the incubation process, the eggs should be buoyed or weakly inflated so that the eggs are in suspension. When the pool is stirred, the pool water is generally stirred with stirring every 30 minutes to 60 minutes. When stirring, stir it up and down. Do not make the pool water vortex to cause the rotation of the fertilized egg to concentrate.
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