What are the key points of production management for sea cucumber pond aquaculture? The Ministry of Agriculture and Rural Affairs has issued the latest guidelines!
Agriculture and Rural Affairs Departments of Hebei, Liaoning, Jiangsu, Zhejiang, Fujian, Shandong, Guangdong, and Hainan Provinces; Fujian Provincial Bureau of Ocean and Fisheries; Agriculture and Rural Affairs Bureaus of Dalian, Qingdao, and Ningbo Cities; Qingdao Municipal Bureau of Ocean Development:
In order to further advance the green and high-quality development of the sea cucumber aquaculture industry and effectively strengthen quality and safety supervision of farmed sea cucumbers, our Bureau, together with the National Fisheries Technology Extension Center, organized experts in the fields of healthy sea cucumber aquaculture and disease prevention and control to formulate the Guidelines for Production Management of Sea Cucumber Pond Aquaculture, which are hereby issued.
Your department (bureau) is requested to organize administrative, law enforcement, extension, and scientific research units within your jurisdiction, in conjunction with the current special campaign to rectify illegal and non-compliant drug use in sea cucumber aquaculture and the science outreach activities on standardized drug use in rural areas, to carry out publicity and training through various media, create a favorable social atmosphere, and ensure the quality and safety of farmed sea cucumbers.
Fisheries and Fishery Administration Bureau, Ministry of Agriculture and Rural Affairs
August 2, 2020
I. Daily Aquaculture Management
(1) Pond Clearing
After a new pond is built and before seedlings are stocked, pond clearing is required. For old ponds, clearing is generally carried out once every 2-3 years. Drain all standing water from the pond, ditches, and channels, repeatedly wash to remove dirt and debris from the pond bottom, dig out excess sludge, then seal the gates and dry the pond for more than 1 week, during which time plow again to turn the unoxidized bottom sludge from the lower layer to the surface for continued oxidation, so that organic matter is thoroughly decomposed. After drying, thoroughly disinfect the pond to kill crabs, wild miscellaneous fish, and other harmful organisms, and to prevent mass proliferation of algae. Disinfection requires the use of quicklime and sodium hypochlorite solution (for aquaculture use), chlorinated lime (for aquaculture use), and other veterinary drugs for aquaculture approved by the state, applied according to the usage and dosage in the product instructions, diluted with water and splashed over the entire pond, soaked for 7-10 days, then drained, followed by introducing seawater for soaking for 2-3 days, then drained, repeating the filling and draining 1-2 times. It is strictly prohibited to use pesticides such as dichlorvos, bulk drug substances, and other toxic and harmful substances for disinfection.
(2) Basic Feed Cultivation
According to whether the water quality in the aquaculture area is rich or lean, seawater may be introduced 10 days in advance before stocking sea cucumber seedlings, to facilitate the reproduction of benthic diatoms and other unicellular algae and provide sufficient basic feed for the sea cucumber seedlings. Apply compound fertilizer with a nitrogen-to-phosphorus ratio of 5:1-10:1 at a rate of 45-75 kg/hectare to fertilize the pond water. Adjust appropriately according to water color, maintaining pond water transparency at about 50 cm and nitrate content in the water below 10 mg/L. Chemical or biological fertilizers that have not been registered with the state must not be used.
(3) Seedling Stocking
1. Seedling Selection
Seedlings should be purchased from provincial-level or higher aquatic original and improved seed farms or seedling production units holding an Aquatic Seedling Production License. Purchased seedlings must have a seedling origin quarantine certificate. When selecting, attention should be paid to uniform specifications within the same batch, with body length above 2 cm, strong vitality and attachment ability, sensitive response to stimulation, and strong contraction.
2. Stocking Timing
Stock in spring during April-May when pond water temperature reaches above 10°C, and in autumn during October-November when pond water temperature is below 22°C. Stocking is best done in the morning or evening, and the "four no-stocking" rule should be followed, namely "no stocking on rainy days, no stocking on windy days, no stocking in high-temperature weather, and no stocking under overly strong sunlight."
3. Stocking Specifications and Density
In spring, the suitable seedling specification is 50-300 individuals/kg, with a stocking density controlled at about 45,000-120,000 individuals/hectare. In autumn, the suitable seedling specification is 20-100 individuals/kg, with a stocking density controlled at about 45,000-48,000 individuals/hectare. Stocking density should be reasonably adjusted according to pond conditions and seedling size.
4. Stocking Method
Before stocking a large batch of sea cucumber seedlings, a small number of seedlings may first be stocked for trial, observed for about 7 days, and after confirming there are no abnormalities in activity and feeding, large-scale stocking can proceed. When stocking, note that the temperature difference between the purchase site and the pond should not exceed 2°C, and the salinity difference should not exceed 5‰. When stocking, evenly scatter the sea cucumber seedlings into the waters where the sea cucumber reefs are located, and observe the distribution, activity, feeding, and survival of the seedlings within 3 days.
(4) Water Quality Regulation
Regularly observe water color, water temperature, water level, salinity, pH, bottom dissolved oxygen, and algae growth in the pond, while carefully observing sea cucumber feeding activity and fecal morphology. Carry out timely water exchange according to tidal cycles and water quality conditions. After heavy rain, promptly discharge the low-salinity surface water; when the temperature difference between inside and outside the pond is large, avoid water exchange or exchange less water. In spring and autumn, maintain the water level at 1 m-1.5 m; during aestivation and hibernation periods, maintain the water level above 1.8 m as much as possible. The main water quality physicochemical indicator requirements are as follows:
1. Dissolved oxygen: required to reach above 3.5 mg/L. When below 2.0 mg/L, juvenile sea cucumbers do not extend their bodies, their attachment ability weakens, and they tend to sink to the pond bottom; when below 1 mg/L, it easily causes sea cucumber death.
2. Salinity: the suitable salinity for sea cucumber growth is 28-32‰. If kept in a low-salinity or high-salinity state for a long time (below 22‰ or above 38‰), sea cucumbers grow slowly, their stress resistance decreases, and diseases occur.
3. pH: growth is better between 7.8-8.5. When below 7.2 or above 9, juvenile sea cucumbers have weakened vitality, growth stops, and death is likely.
4. Ammonia nitrogen: the semi-lethal concentration is 1.65 mg/L. The higher the pH, the greater the proportion of undissociated ammonia. Non-ionic ammonia can inhibit the normal growth and development of sea cucumber seedlings and reduce their resistance to disease.
5. Hydrogen sulfide: bottom sludge, residual bait, carcasses, feces, and the putrefactive decomposition of organic matter are the main sources of hydrogen sulfide. The safe concentration is below 0.002 mg/L.
(5) Feed Feeding
Sea cucumbers grow fastest in spring and autumn when water temperature is 10°C-20°C. When basic feed is insufficient, feed may be provided manually, with the feeding amount adjusted according to sea cucumber feeding and growth rate. Generally, each feeding is about 0.5% of sea cucumber body weight, once every 7-10 days. Feeding should stop during aestivation when water temperature exceeds 20°C and during hibernation when it is below 5°C. Strictly comply with the Regulations on the Administration of Feed and Feed Additives. Artificial feed is compounded from raw materials such as Sargassum powder, Sargassum thunbergii powder, kelp powder, and fish meal in certain proportions, or commercial special compound feed for sea cucumbers may be used, generally with crude protein in the range of 18-25% and fat not exceeding 5%. The hygiene standards of the sea cucumber feed fed should comply with the Feed Hygiene Standard (GB13078-2017), and quality standards should comply with the Compound Feed for Apostichopus japonicus (SC/T2037-2006) and other relevant provisions.
(6) Disease Prevention and Control
1. Preventive measures: prevent overfeeding, keep the pond bottom and water quality clean, and prevent diseases such as skin ulcer syndrome. Appropriately increase water depth, reduce pond water transparency, prevent the proliferation of large algae, promptly remove large algae from the pond, and prevent deterioration of the pond bottom environment caused by algal death and decay. In summer, high-temperature disasters can be prevented by increasing pond water depth, reducing pond transparency, installing shade nets, and using pond cooling equipment. Use ground cages or light at night to trap crabs and other harmful organisms, reducing the amount of harmful organisms in aquaculture ponds.
2. Treatment measures: use veterinary drugs for aquaculture approved by the state, strictly follow the usage and dosage in the instructions, and prohibit the use of fake and inferior veterinary drugs as well as state-banned drugs and other compounds. Strictly implement the drug withdrawal period system.
(7) Prevention and Removal of Biological Enemies
During the aquaculture process, clear the pond regularly, control the timing of water intake, and install iron wire mesh with a pore size of 1 cm-2 cm at the water inlet to filter aquatic plants and debris. Without affecting water filtration, add 2-3 layers of 30-50 mesh polyethylene netting to intercept and filter large algae and harmful organisms such as fish, shrimp, and crabs.
1. Large algae such as Enteromorpha: in early spring, control the algae-bacteria phase and maintain pond water transparency at about 30 cm, which can effectively prevent mass proliferation of large algae such as yellow tube weed. If large algae proliferate in the pond, they can first be promptly removed manually; it is strictly prohibited to apply herbicides (algaecides) or other pesticides.
2. Biological enemies such as fish, shrimp, and crabs: shrimp and crabs can be trapped with ground cage nets, carnivorous fish can be caught and killed with gill nets or hooks, and any starfish found should be picked out of the pond and dried in the sun.
II. Other Technical Points
(1) Precautions for Aquaculture During Flood Season
Aquaculture ponds should be equipped with freshwater drainage valves (gates), and during concentrated rainfall in flood season, the freshwater layer at the top of the pond should be quickly drained. After flood season, thoroughly remove decaying miscellaneous algae, closely monitor dissolved oxygen in the aquaculture pond water, and when it is below 3 mg/L, mechanical aeration methods may be used to increase oxygen.
(2) Precautions for Aquaculture in Summer
During high-temperature periods, pond water depth should be increased to above 1.8 m to avoid sudden changes in water temperature with air temperature. For ponds smaller than 4 hectares, shade nets may be added during high-temperature periods, with the laid area preferably covering 3/5-2/3 of the pond area, and the height of the shade net above the water surface greater than 1.5 m. Low-temperature water pipes may also be used for cooling, which can also increase dissolved oxygen in the pond water and effectively lower water temperature by 1-2°C. To prevent death from high summer temperatures, sea cucumbers in the pond may be transferred to summering workshops for temporary holding, and moved back when the pond water temperature is suitable.
(3) Precautions for Aquaculture in Winter
In winter, pond water depth should be increased to above 1.8 m. After ice forms, promptly open ventilation holes, promptly clear snow from the ice surface, increase pond water transparency, enhance photosynthesis of phytoplankton in the water, regularly monitor dissolved oxygen, and ensure that sea cucumbers do not die from lack of oxygen or develop diseases due to oxygen supersaturation. Patrol the pond promptly to prevent leakage from pond gates.
The above guidelines are for reference. For sea cucumber aquaculture production, please strictly comply with relevant laws, regulations, and standards.