Detailed Explanation of Key Jellyfish Aquaculture Techniques and Management Methods
The jellyfish is a warm-water large edible jellyfish that lives in the northern temperate seas. As early as the late 1980s, there were reports in China of artificial breeding and release of jellyfish, but due to the limitations of conditions, awareness and technology at the time, jellyfish were unable to form large-scale production. Let's take a look at jellyfish aquaculture techniques below!
Pond Selection
1. Choose a pond relatively close to the sea with convenient water intake and drainage (ideally able to exchange water even during neap tides).
2. It is best to have a freshwater source near the pond so that the water salinity can be adjusted.
3. The pond size should preferably be more than 20 mu; the larger the better.
4. The water depth should be more than 1 m, with 1.5-3 m being most suitable.
5. The bank slope should be as steep as possible. If the slope is too gentle, a fence net or plastic sheeting should be added at a water depth of 0.5 m along the bank to prevent jellyfish from beaching themselves and dying, so pay attention to this.
Preparation Before Releasing Seedlings
1. The water inlet should be fitted with a fence net to prevent the entry of harmful organisms such as trash fish and trash shrimp. The mesh size of the fence net should be about 40-60 mesh. The pond's drainage outlet should also be fitted with a fence net, and the mesh size should be the same as that of the water inlet to prevent seedlings from escaping during drainage. The area of the fence net should be larger, depending on the specific pond size. The mesh size can gradually increase as the jellyfish grow. During drainage, the water flow should be as gentle as possible to prevent jellyfish seedlings from sticking to the drainage net and dying.
2. Seedlings can only be released 10 days after filling with water. After filling, the water can be fertilized appropriately according to conditions to ensure a certain amount of zooplankton.
3. Test the water quality, mainly water temperature, salinity, pH value, etc. This work should be done by technical personnel, and you can seek help from the seedling producer. It must be accurate, as this affects the survival rate after seedling release.
4. Inform the seedling producer of the aquaculture pond's water temperature and salinity before releasing seedlings. Only by seeing how large the difference is between the indoor and outdoor pond water quality conditions can it be determined whether seedlings can be released. The suitable water temperature range for jellyfish aquaculture is 15-35°C, with 22-28°C being most suitable. The suitable salinity range is 8‰-36‰, with 18‰-30‰ being most suitable.
5. For ponds with too gentle bank slopes, a fence net or plastic sheeting should be added at a water depth of 0.5 m along the bank before releasing seedlings.
Releasing Seedlings into the Pond
1. The seedling release time should be chosen on a morning or evening with good weather, preferably windless weather without direct sunlight.
2. The seedling release density should be strictly controlled below 300 individuals/mu. Excessive density will cause oxygen deficiency, slow growth, failure to grow large, and other problems. The specific release density should be linked to the pond size, water depth, water quality conditions and water exchange conditions. Where conditions are good, the density can be higher; where conditions are poor, definitely do not release too many, otherwise aquaculture failure may result.
3. During transport, jellyfish seedlings should be oxygenated, shaded from light, and iced to prevent temperature rise.
4. When releasing seedlings, pour the seedlings into a relatively large container, add some pond water, and let the seedlings adapt for a period (10-20 minutes) before putting them into the pond.
5. It is best to transport the seedlings directly to the middle of the pond and sprinkle them evenly and slowly into the pond. The operation must not be rushed, to prevent injuring the seedlings.
Aquaculture Management
1. After releasing seedlings, if the weather is normal and water quality conditions are normal, no water exchange is needed within 7 days. After 7 days, a small amount of water can be exchanged (no more than 20% each time).
2. In the early stage of jellyfish aquaculture (10-20 days), ponds with good water exchange conditions can exchange water daily, and the principle of exchanging little but frequently should be followed. For intake and drainage, it is best not to use large-volume filling and draining, as this will harm the seedlings (such as seedlings sticking to the net and dying), especially before the jellyfish bell diameter grows to 5 cm.
3. In bad weather such as strong wind or heavy rain, it is best not to exchange water, so as to avoid too great an environmental change that could adversely affect jellyfish growth.
4. Before exchanging water, measure the temperature and salinity of the new water to be exchanged. The difference from that in the pond must not be too large. The salinity variation range must not exceed 10‰; if it exceeds this amount, water must not be exchanged.
5. The salinity of the pond water should preferably be maintained between 20‰ and 30‰. For ponds with freshwater resources nearby, freshwater should be fully used to adjust the pond water salinity. Within the suitable range, maintaining relatively lower salinity is very beneficial to jellyfish growth. However, freshwater must be added evenly, and jellyfish must not die because of excessively low local salinity.
6. Observe jellyfish activity and growth at all times, and monitor changes in water quality and the amount of zooplankton in the water.