Artificial culture technology of jellyfish

In China, jellyfish fishery has a long history, with the highest annual output reaching 58000 tons. However, due to reasons that are not fully understood so far, its resources vary greatly from year to year, sometimes too much to be processed, lying on the beach, and sometimes nowhere to be found.

Artificial culture technology of jellyfish

The choice of pond

Choose a pond that is close to the seaside and easy to enter and drain (preferably neap tide can also change water).

It is better to have fresh water resources near the pond to adjust the salinity of the water.

The size of the pond should be more than 20 mu, the bigger the better.

The water depth is more than 1 meter, and 1.5-3 meters is the most suitable.

The slope of the bank should be as steep as possible. if the slope is too slow, purse seine or plastic sheet should be added at the water depth of 0.5 meters to prevent the death of jellyfish, so pay attention.

Influent and drainage of pond

There should be a purse seine at the inlet to prevent the entry of miscellaneous fish, shrimp and other enemy organisms, and the mesh of the purse seine should be about 40-60 mesh. The drain of the pond should also be equipped with a purse seine, and the mesh should be the same as that of the inlet to prevent running seedlings during drainage, and the area of the purse seine should be larger, depending on the size of the pond. The size of the mesh can gradually increase with the growth of the jellyfish, and the water flow is as slow as possible to prevent the jellyfish seedlings from sticking to the drainage net and die.

The seedlings can not be released until 10 days after entering the water, and the water can be fertilized properly according to the situation to ensure that there is a certain number of zooplankton.

Preparation work before releasing seedlings

The detection of water quality mainly includes water temperature, salinity, pH value and so on. This work should be completed by technicians, you can turn to seedling manufacturers, must be accurate, which is related to the survival rate after seedling release.

Inform the seedling manufacturer of the water temperature and salinity of the culture pond before releasing the seedlings, and see the difference in the water quality of the indoor and outdoor ponds to determine whether the seedlings can be released or not. The suitable range of water temperature for jellyfish culture is 15 ~ 35 ℃, and the optimum range of salinity is 22 ~ 28 ℃, and the optimum range of salinity is 18 ‰ ~ 30 ‰.

Ponds with a slow slope on the bank should add purse seine or plastic sheeting at a depth of 0.5 meters before releasing seedlings.

Release seedlings

Seedling time should be chosen in the morning or evening when the weather is better, preferably when there is no wind or direct sunlight.

The density of seedlings should be strictly controlled below 300 / mu. Excessive density will lead to hypoxia, slow growth, lack of growth and so on. The specific seedling density should be related to the size, water depth, water quality and water exchange conditions of the pond. The density with good conditions can be higher, and those with poor conditions must not be released more, otherwise it may lead to culture failure.

Sting seedlings should be oxygenated, shaded and iced when transported to prevent heating.

When releasing the seedlings, pour the seedlings into a larger container and add some water from the pond to let the seedlings adapt for a period of time (10-20 minutes) and then put them into the pond.

It is best to transport the seedlings directly to the middle of the pond, evenly and slowly sprinkle into the pond, the operation should not be impatient, in case of injury to the seedlings.

Culture management

Jellyfish culture basically uses the method of not feeding, so changing water (natural bait to supplement the water body) is very important for jellyfish culture.

If the weather is normal and the water quality is normal after seedling release, there is no need to change water within 7 days, but a small amount of water can be changed after 7 days (no more than 20% each time)

In the early stage of jellyfish culture (10-20 days), ponds with good water exchange conditions can change water every day, and the principle of less change and frequent change should be followed. It is best not to drain and drain water, which will harm the seedlings (such as the seedlings stick to the Internet and cause death), especially before the umbrella diameter of the jellyfish grows to 5 centimeters.

In case of bad weather, such as strong wind and heavy rain, it is best not to change the water, lest the environment changes too much and adversely affect the growth of jellyfish.

The temperature and salinity of the new water to be changed should be measured before the change of water. The difference between the temperature and salinity of the new water to be changed should not be too great. The change range of salinity should not exceed 10 ‰, and the water cannot be changed beyond this amount.

The salinity of pond water should be kept between 20 ‰ and 30 ‰. For those ponds with fresh water resources nearby, fresh water should be fully used to adjust the salinity of pond water. Keeping relatively low salinity in a suitable range is beneficial to the growth of jellyfish. However, the injection of fresh water should be uniform, and the death of jellyfish should not be caused by local low salinity.

Observe the activity and growth of jellyfish at any time, monitor the change of water quality and the amount of zooplankton in the water.

The number of bait creatures.

In the early stage of jellyfish pond culture, the plankton in the pond is abundant, but in the later stage of culture, the number of plankton in the pond can not meet the growth needs, so fertilizer and water should be carried out. There are three main methods to fertilize and water: first, chicken manure hanging bag fertilizer water, using fermented chicken manure 10 kg / bag, hanging bag 150 / bag. When the transparency of the water reaches 40 cm, take out the chicken manure bag immediately to prevent the water quality in the pond from being overfertilized. The ratio of 5 kg / h to water, and the third is to put phosphate fertilizer into water at the ratio of 30 kg / h to water. In addition, artificial feeding of natural rotifers, Artemia or Cladocera can also be used for live feeding. In the case of high density of jellyfish culture, it can also provide bait for jellyfish by feeding ground surimi. However, this method must follow the feeding of jellyfish around the pond and adhere to the principle of "throwing less and throwing frequently".

Water quality management.

When raising jellyfish in a pond, the water body must be changed frequently in order to maintain the water quality of the pond. By changing water, it can not only provide enough bait organisms for the growth of jellyfish, but also ensure that the water body is fat, tender and fresh, which can stimulate and promote the growth of jellyfish. To change water, we must insist on changing less and frequently, and avoid large discharge and large irrigation. The seaweed in the pond is also very important for the maintenance of water quality, and the seaweed in the pond should be removed regularly. The study shows that the dominant population in the pond can be cultivated by artificial inoculation of Chlorella, the pond environment can be improved, the natural bait of jellyfish can be cultivated and the culture cost can be reduced.

Keep the balance of physical and chemical factors in the water.

It is found that the dissolved oxygen of jellyfish is less than 3mg/L and the value of ammonia nitrogen is more than 374.45 Lg / L, which can be considered as the threshold of jellyfish death. Only when the water temperature is 18 ~ 28e, salinity 18 ~ 28j, pH value 7.5 ~ 8.5, dissolved oxygen\ 1.5 mg / L, jellyfish is active, food intake increases and grows rapidly. Therefore, attention should be paid to regulating the physical and chemical factors of the water body in an appropriate range. When the temperature difference of water temperature is less than 3 e, the pH value is stable at 7.5-8.5, and the ammonia-nitrogen value is less than 0. 5%. When the concentration is 2 mg / L, the seedlings can be released.

The primary productivity of water bodies.

It is found that in the process of jellyfish culture, the primary productivity of water is not only affected by seawater transparency, but also affected by light, salinity, nutrients and other factors. According to the direct relationship between transparency and primary productivity, within a certain range, the transparency of the water body should be improved by injecting fresh water, which is generally controlled at 30-50 cm, so as to ensure sufficient primary productivity and promote the rapid growth of jellyfish.

Seedling cultivation

Preparatory work

Nursery ponds are used to store seed stings and cultivate larvae, either in large containers, preferably in smooth cement ponds.

The attachment base is used for polyp attachment, any hard and non-toxic substance can be used, and corrugated plate is best used for large-scale production.

Other Artemia hatching had better have a special cement pool. There are no special requirements for heating, intake and drainage systems, and the general production environment can meet the requirements.

The source of parent stings

There are two sources of parent stings: one is fully artificial culture, which is mainly suitable for areas where it is very difficult to collect parent stings from natural sea areas, such as the coast of Zhejiang. The other is a kind of naturally harvested sexually mature species of stings, which can be divided into natural sea areas and artificially released shrimp ponds according to the location of collection. Relative to the quality of the species, no matter the number of eggs or the size of the individual, the latter is better than the former. And from the point of view of the culture situation in the past two years, the jellyfish caught in the culture pond has a serious degradation phenomenon due to the genetic relationship between species of jellyfish, such as uneven individual size, mostly small jellyfish.

Spawning and hatching

At the natural water temperature during the peak breeding period, the unfertilized eggs disintegrated after 3 to 5 hours, and the fertilized eggs began to cleavage after a period of time, and then developed into early floating wave larvae.

Artificial incubation program

Water storage and water treatment: brush the pool before entering the pond and inject new sea water to serve as an incubator. Adding EDTA (disodium ethylenediamine tetraacetic acid) to the seawater to complex heavy metal ions is beneficial to improve the hatching rate.

Sex ratio: 2:1 is the best sex ratio. The suitable density of parent jellyfish is beneficial to the emission of induced products between male and female individuals.

Sampling microscopic examination: after moving into the parent sting, you should constantly take samples from the bottom of the pool under the microscope to observe whether to lay eggs and whether there is cleavage. After that, the samples were sampled and observed at regular intervals until a large number of divided or unfertilized eggs were found to be no longer fertilized.

After all the hatched embryos were transformed into floating wave larvae, the volume method was used to quantify them. Under normal circumstances, the hatching rate is above 90%.

Metamorphosis, attachment and management of floating wave larvae

The floating wave larva rotates to the left and becomes a polyp after a period of time. The front end is attached to form the foot and handle, and the back end forms the mouth and tentacles. If the attachment base is not encountered during metamorphosis, the handle is abnormal in the floating state, and the handle is upside down and suspended on the water surface. There are sticky cells at the end of the stalk, which are easy to attach when in contact with the attachment base. After the floating wave larvae metamorphosed into polyps, most of them attached to the lower side of the corrugated plate. Fresh sea water should be added at the right time after the polyp is attached.

After the larval culture pond is filled with water, the following four management measures are generally taken: first, to control the light to prevent a large number of miscellaneous algae from multiplying on the seedling attachment, so as to improve the survival rate of polyps. Second, keep the temperature. After the water temperature in the autumn pond drops below 10 ℃, there should be warm facilities in the room. It is better to keep the water temperature at 5: 10 ℃. When the indoor water temperature rises to a suitable temperature in spring, the polyp larvae begin to reproduce transversely, and then the butterfly larvae are released. Third, timely bait, with rotifer, flexopod nauplius, Artemia nauplius and so on as bait, feeding frequency depends on water temperature and feeding condition, usually once a day. The polyp larvae are yellowish after being full and pale when hungry, so the feeding frequency and feeding amount can be increased or decreased according to the color depth of the polyps, mainly based on microscopic examination; fourth, when the water is changed at the right time, the polyp larvae are small, less active, and have low oxygen consumption and fewer metabolites. Under 20 ℃, the water temperature is low and the metabolism is slow, so it is not necessary to change water frequently. When changing water, the sea water with sediment is sucked out by siphon from the bottom of the pool, and then the same amount of fresh sea water is added.

A stolon grows on the side of the polyp, which is attached to its end to form a new landing point. The end of the original handle gradually moves away from the attachment point. The process of forming foot sac can be carried out continuously, and the average individual can form one to more than a dozen foot sacs. After the foot sac is formed, new polyps can sprout from the top under appropriate conditions. The new polyps can also form new foot sacs and sprout a generation of polyp larvae during and after growth.

Discoid larval culture

When the temperature of the polyp rises to the appropriate temperature in the following year, transverse cleavage begins to appear. The number is closely related to the size of polyps, generally about 1 ~ 7. The primary discs are colorless, translucent, 2mm in diameter. After 7-10 days of growth, the umbrella diameter reached 10 mm, for the middle butterfly or juvenile stings, after 15-20 days of growth, the umbrella diameter reached about 20 mm, becoming a young sting.

The following points should be paid attention to in the cultivation of discs:

Regular and quantitative feeding: it usually takes 3 to 4 hours to digest the food after eating, so it is generally fed every 4 hours, and a small amount of adjustment is made according to naked eye observation and microscopic examination.

Water change: the dish body has high temperature and large food intake in the cultivation stage, and the metabolites and residual bait produced are easy to corrupt the water quality. This requires us to change the water in time, and the amount of water change is half a day at the initial stage of dish cultivation, which is completed twice. In the middle and later stages, the full amount of water can be changed (if the water quality is not good, the whole pool water can be changed twice a day). Once the whole pool water is changed, the pool water should not be drained at once, but should be completed three or four times.

Inflatable: the rim valve and network management of the primary disc have not yet developed, the planktonic ability is very weak, and most individuals settle at the bottom of the pool. Micro-inflation is generally used to promote its plankton, feeding and growth. Under artificial control conditions, the survival rate from dish larvae to juvenile stings is generally more than 90%. The survival rate at the stage of young stings can reach more than 85%.

Sell

When the young sting grows to more than 2 cm, it reaches the sold specification and should be sold quantitatively by volume method.

We used shrimp culture pond to carry out three-dimensional ecological culture experiment of jellyfish, inoculated fertilizer and water to cultivate basic bait, using photosynthetic bacteria to improve water quality and other means to optimize the culture environment. At the same time, multi-variety culture is carried out, which not only makes full use of the water body, but also improves the comprehensive culture benefit.

Materials and methods

① pond selection: use the pond 500mu, the average water depth is more than 2m. The intake and drainage is smooth, and there are blocking facilities around the pool.

② disinfection: disinfect with 200kg/667 lime to kill enemy organisms and pathogens.

③ influent: enter 30cm with 80-mesh sieve and disinfect it with 30 × 10 mol bleach containing 32% chlorine.

④ seedling release: release seedlings above umbrella diameter 1.5cm. The combination of nursery room and soil pond was used for temporary breeding. Feed high-quality nauplii, rotifers, cladocera and so on during temporary cultivation.

⑤ jellyfish harvest: when the commodity specification of the first jellyfish reaches about 3kg/, catch with a large buckle net; the second jellyfish can be raised to 4~5kg/ according to the market situation; the third jellyfish can be listed in advance, so it will not affect the shellfish harvest.