Key techniques of artificial breeding of abalone

Abalone is a kind of valuable sea treasures. In recent years, artificial culture of abalone in China has developed rapidly, so abalone breeding is very critical, so how to raise abalone artificially and what is the specific operation process? Let's introduce it in detail below.

(1) heating up to promote ripening

The natural spawning period of Haliotis discus hannai in the Yellow Sea and Bohai Sea begins after late July. if the seedlings are collected by natural mature abalone, by the middle of January of that year, the average individual of abalone is small and the survival rate of overwintering at sea is low. In addition, when collecting seedlings in July and August, because the water temperature of cultivation has exceeded 20 ℃, the bait of benthic siliceous grass propagates slowly and falls off easily, so it is difficult to guarantee the feed of breeding abalone in the early stage. It is good to solve these problems and improve the effect of collecting eggs by accelerating ripening and collecting seedlings of abalone.

The equipment needed for heating cultivation are: heating equipment type nursery room, cement pool or fiberglass flume as culture pool, electric heating equipment or boiler preheating pool, hyperactivity equipment.

According to the calculation of fecundity, 0.5 female abalone with a shell length of 7.5 mi 8.5 cm per square meter can meet the needs. According to 1/5 of the remaining b species of female abalone, the heating and ripening promotion of male abalone should begin two and a half months before seedling collection and the effective accumulated temperature can meet the requirements.

Cultivation method: about 80 species of abalone per cubic meter of water should be placed in a cage and raised. The bottom of the cage is covered with a black corrugated attachment board. At the rate of increasing 2C per day, the natural water temperature gradually rises to 20C, and then the constant temperature is maintained. Feed fresh undaria pinnatifida or kelp every 3 days with a daily feed of about 20% of the body weight. Change the fresh sea water once a day. The fresh sea water should be preheated first, and the temperature difference should not exceed ±1.5 ℃. You can move the cage when changing water. In the process of cultivation, the inflatable capacity of not less than 100 liters of Sichuan and cubic meters per hour should be maintained. Note: the water temperature should not exceed 20C, often remove the residual bait.

(2) Egg collection

1. Selection of abalone

The excellent breeding abalone is easy to collect eggs, the hatching rate is high, and the embryo body develops well. The conditions for selecting breeding abalone are as follows: the shell length of abalone is more than 6 cm, and the length of abalone body is more than 8 cm. The gonadal appearance is extremely plump, covering most of the stomach and liver, the base protrudes at the edge of the shell, and the end becomes obtuse because it is full of gonads.

two. Induce labor

It is also possible to use temporary breeding and natural spawning, but it is generally necessary to use various means to stimulate abalone to spawn. The common methods are as follows:

(1) Ultraviolet irradiation of sea water

The principle of this method is not clear, but the induced spawning rate can reach 100%. The selection of running water ultraviolet germicidal lamp is more convenient, such as the use of general quartz ultraviolet sterilization radiation tube (30 watts), insulation measures should be taken, wiring column with insulation lead, and then sealed with epoxy resin. Put the germicidal lamp in the tank and inject 23 ℃ freshly filtered sea water into the tank. If the water level exceeds a certain height of the lamp tube, the lamp can be illuminated. The exposure dose is usually 300ml 500mg / hour. Liter is fine, and the exposure inch can be determined according to the power of the lamp and the volume of the seawater.

Egg harvesting is best carried out in the middle of the night. Abalone is dried in the shade before entering the ultraviolet radiation water, and the effect is the best. The method is to put the abalone feet upward, cover with a layer of clean and moist gauze at room temperature, and dry under the shade for about 1 hour.

In order to facilitate the operation, the egg trough should not be too large, in the absence of special products, the market can use 30 liters of polyethylene basin. When collecting eggs, the male and female are separated, and one or more egg collecting troughs are released and injected into the sea water irradiated by ultraviolet rays. Within one hour, most individuals, except a few, cannot lay eggs. At this time, the water irradiated by ultraviolet rays should be changed. It will not take long for abalone species to ejaculate and lay eggs in large quantities. Male abalone can ejaculate quickly, so the induction time can be 0.5-1 hour later than male abalone to ensure sufficient sperm motility during artificial insemination.

(2) hydrogen peroxide method

This method is simple and convenient, and no special equipment is needed.

You can use commercial hydrogen peroxide (30% H2O2) reagent or hydrogen peroxide (30% H202) for medical detoxification. The preparation concentration is 4 moles, that is, 0.3 milliliters of hydrogen peroxide is added to one liter of seawater.

When collecting eggs, the net bags made of plastic window screen were filled with selected female and male abalone, immersed in mixed hydrogen peroxide sea water for half to 1 hour, washed with sea water, and put into the egg trough to add about 23 ℃ of fresh sea water to ovulate and lay eggs within 1 hour.

3. Artificial insemination

When the water temperature is above 20 ℃, artificial insemination must be completed within 1 hour of egg production. During insemination, it is best to quantify the number of eggs and semen density first. the results show that the fertilization rate is the highest according to more than 1500 sperm per egg or more than 300000 sperm per milliliter. If the concentration is too high, it is easy to rupture the egg membrane, and if it is too low, the fertilization rate is not ideal. But in production, it is often too late to measure, using the method of adding semen while laying eggs. Fertilization in time, egg vitality is also strong, as long as the dosage is generally appropriate, the effect is also very good.

(3) hatching of fertilized eggs and cultivation of larvae

1. Wash eggs

Mainly make use of the characteristic that the relative density of the egg is greater than the relative density of the sea water, soak with sea water to remove the excess sperm in the water and around the fertilized egg. The method is as follows: fill the egg trough with freshly filtered sea water, the water temperature should not be lower than 20C, and rest for 30 minutes. After the egg is fully sunk, the upper layer of clear water is poured out by tilting the egg trough and refilled, generally repeated more than 5 times, and the water is changed once an hour from egg washing to larva floatation.

two。 Incubation and breeding

Usually it can be hatched directly in the egg collecting trough. under normal circumstances, it takes 13 hours from egg fertilization to hatching the trochophore larva to surface, and the floating body floats because of its phototaxis. Making use of this characteristic, the surviving body can be selected, and the moving body and sea water can be poured into another tank together, and the rest of the bottom liquid can continue to be selected. In the selection and breeding of torsion wheel, cloth cage can not be used to concentrate, which is easy to cause mechanical damage, and cloth cage can be used to change water when entering the moving stage of face plate.

Note: during the floating period, there is no need to give bait or some unicellular algae, the animal needs to change water frequently, and the new sea water must be filtered. The flume also needs to be scrubbed and kept clean, and the mechanical damage to the moving body should be avoided as far as possible in the process of changing water. if there are conditions, the oxygen content, pH value, dissolved oxygen, soluble organic matter and hydrogen sulfide content of seawater are often measured in daily work. to ensure the normal life of the moving body.

(4) attachment and cultivation of juvenile abalone

1. Production of bait board

The corrugated plate made of polyethylene plastic film or transparent plastic or plexiglass (cut into a belt and corrugated wrapped on the support) can be used. Soak in 0.5% sodium hydroxide for two days before use, then rinse the detergent solution and wait for use.

Benthic diatoms can be collected on the white rock or on the wall of the indoor culture pond, after microscopic examination, the selection of small boat algae, ceratophyta, ovoid algae, etc., when collecting algae species should be careful not to mix with a large number of green algae.

The inoculation time should begin one and a half to two months before the seedling is collected, and a suitable shelf should be set up so that the bait board is placed horizontally in the pond, arranged neatly, injected into the filtered sea water, and the algae species are also poured into the inoculation pool after being filtered, and after being fully stirred, they are allowed to be inoculated automatically, and the plate is reversed the next day, so that the inoculation is carried out. After vaccination, evacuate, put the bait plate vertically on the shelf, and replenish nutrients in the pool. Nutrients include 1.2 grams of urea, 22 grams of potassium dihydrogen phosphate, 24 grams of sodium silicate and 24 grams of ferric citrate, adding 500 milliliters of fresh water to make the mother liquor, 100ml per cubic meter of pool water, changing the water once a week, and replenishing nutrients according to the standard after the change of water.

In the process of cultivation, attention should be paid to the frequent change of the direction of the bait board. The light should not be too strong, so kill copepod pests in time.

two。 Attachment of creeping body

The time from plankton to creeping period is 20 ℃, about 52 hours after floating, including preheating sea water and washing bait plate to remove pests and algae.

The amount of the moving body is determined according to the area of the board when the bait plate is placed in the pool at a depth of 10ml / 20cm from the surface of the water. When the bait plate is 22 square meters per cubic body of water, the amount of the plate moving body is between 40,000 and 50,000. If the density is too high, the growth is slow and the survival rate is low. After entering the pool, the light should be reduced and inflated to ensure uniform adhesion.

In the early stage of attachment growth of abalone, attention should be paid to fertilization and water change. in order to maintain the proliferation of feed diatoms, fertilizer should be applied in combination with changing water every day after attachment for one week, and the amount of mother liquid should be added to 20ml per cubic meter of water. When changing water, it should be taken into account that the attachment of the larvae is not yet completely fixed, and the overflow outlet should adopt a filtering device to prevent the loss of moving bodies. In addition, we should also pay attention to timely killing pests and monitoring water conditions and growth conditions.

3. Transfer to cage flow plane feeding

The Japanese aquaculture industry used to transfer to cage feeding after the shell length of the young abalone was 6mil 7mm, and the individual size of the abalone was large, and the benthic diatom feed was difficult to meet the needs. Now it is considered that the formation period of the first shell hole of abalone (1Mel 3mm) is the key period for food conversion. Japanese culture experiments show that the survival rate is 88% when frozen undaria pinnatifida is cut into proper algae slices, and the growth rate is faster. Therefore, when the shell is 3 mm long, it can be moved into the cage, and the young abalone likes to live in seclusion from the light, so it is necessary to use a black attachment plane. At present, FRP and polyoxyethylene corrugated plates are widely used, and a certain number of holes are drilled on the board to facilitate the crawling of abalone, and the corrugated plate is fed in a cage. At this time, flowing sea water should be used instead of regular water exchange, and the flow rate should be 7 times larger than that of feeding water. The dissolved oxygen content is not less than 3 ml / L, and the specific measures are as follows:

(1) peeling off of young abalone

Young abalone needs to be stripped from bait board to cage, individual selection during cage feeding, excessive from indoor to sea, etc. There are two common methods:

Chemical anaesthesia stripping method: 10% ethyl carbamate solution or 20% alcohol solution prepared with sea water can make the young abalone lose its adsorption. Spread nylon silk cloth in the tank containing the medicine solution to pick up the peeled young abalone, and dip the bait plate together with the attached young abalone into the medicine solution. 1 after 2 minutes, the young abalone raises the shell and twists it in place. At this time, the vibrating bait plate or gently rubbing with an artificial sponge can make it fall off, and the peeled young abalone should be taken out and washed as soon as possible, not more than half an hour.

Temperature stimulation stripping method: this method is used to peel off young abalone when it is excessive from indoor to sea water in spring and autumn. The effect is better when the cultivation temperature is 12C. First, the corrugated plate and the young abalone were immersed in high temperature sea water about 8-IOC higher than the cultured water for about half a minute, and then immediately returned to the normal temperature sea water, the young abalone will be strenuous activity, at this time wearing thread gloves can be peeled off by hand. Put the net cage at the bottom of the normal temperature and high temperature sink to collect the young abalone.

(2) bait shaking selection

Artificial bait can be used to replace algae completely, the supply of artificial bait is guaranteed, easy to use, not limited by the season, and its feeding effect is better than that of seaweed feeding. The abalone fed only with undaria pinnatifida grew 2.5 times of its body weight in 5 months, while the body weight increased 4.1 times when it was fed with artificial diet. Artificial bait is undaria mixed with white fish meal and vitamin and so on. Its protein content is 27.1%, while that of dried undaria is only 11.4%. The amount of feeding is related to individual size and water temperature. Generally, the daily feeding amount can be controlled at 5%-7% of body weight, and the time should be in the evening.

(3) feeding management and overwintering

The focus of management is to maintain water quality, often remove residual bait, clean cages and pool walls, and prevent local obstacles to water outage and cage water supply. If there is a phenomenon that young abalone climb out of the board painting or climb out of the water in large numbers along the wall of the cage during the day, the pool will be cleaned immediately to change water, otherwise a large number of young abalone will suffocate to death, and peeling and selection will be carried out at the same time, about a month after the young abalone is transferred to the cage for breeding. when the average shell length is about 6 mm, the individual size is different, that is, the large, medium and small individuals should be selected in time.

In the northern region, if the young abalone seedlings are bred at sea in late autumn and early winter, the water temperature is lower, the young abalone is small, and the survival rate is low. If the water temperature rises and the individual goes into the sea after the middle of April of the second year, the survival rate will be significantly increased, so indoor overwintering is a necessary and effective measure.

At present, the indoor overwintering technology of a large number of young abalone is not perfect, there are two main methods:

According to the water purification machine method, the overwintering pond is equipped with a plastic film greenhouse, and each pool is equipped with a sewage purifier, which has the dual function of increasing oxygen and purifying water quality, the water temperature is kept above 15 ℃, fresh seaweed is fed, and generally there is no need to change water.

The overwintering method of the original cultivation pond is carried out directly on the basis of cage running water feeding, with a high survival rate, but high energy consumption and high cost, so it needs to change water. In order to reduce energy consumption, seawater should be recovered and recycled after filtration.