A Detailed Guide to Abalone Sea Hanging Culture Methods and Farming Requirements
Abalone is called the soft gold of marine organisms; its flavor is delicious, its flesh delicate and tasty, and it is rich in nutrients with important economic value. At present, abalone farming methods include bottom sowing culture, raft cage culture, industrial farming and tunnel farming. In 2003, the author carried out exploration of abalone sea hanging culture technology in the Gangyu sea area of Lianjiang and achieved relatively good economic benefits. The relevant details are introduced below for reference by peers.
Seedling selection, transport and stocking
1. Seedling selection
Select healthy seedlings bred locally and subjected to quarantine. The shell length of abalone seedlings should be greater than 1.5cm, with an intact body shape, a plump appearance, no deformities, strong vitality and strong attachment ability.
2. Seedling transport
Use the dry transport method to transport abalone seedlings, with 500 seedlings per mesh bag, placed in foam insulated boxes and transported to the farming area by vehicle and boat. The usual transport survival rate is above 99%.
3. Seedling stocking
Before releasing seedlings, learn about the weather conditions in advance and avoid strong winds, heavy rain and high-temperature weather. When releasing seedlings, pay attention to changes in temperature and salinity between the nursery pond and the farming area, and control the temperature difference and salinity difference within 2℃ and 2‰ respectively. The stocking density is 100 individuals/layer (shell length 1.5cm). The water layer for hanging culture of abalone cages is controlled at 3m to 5m.
Farming management
1. Feed feeding
The feed is mainly fresh kelp and dried kelp, salted kelp, and compound flake feed. During the farming process, the type of bait is selected according to the season. From April to June (before the Dragon Boat Festival), feed fresh kelp; from July to September, feed salted kelp, supplemented by natural algae such as sea lettuce and gracilaria or compound flake artificial feed; from October to March of the following year, feed nori or salted kelp. The feeding amount of fresh bait is 10% to 30% of the abalone body weight, and it should be increased or decreased as appropriate according to water temperature and the feeding condition of the abalone; feed appropriately less during the high-temperature period in summer; feed more during the low water temperature period in winter. Feeding is generally once every 2 to 3 days. Before feeding, thoroughly remove residual bait and accumulated sludge: feed appropriately less during the high-temperature period in summer, once every 3 days; when the water temperature in winter is below 12℃, feed once every 4 days.
2. Farming density
Adjust and divide seedlings at the appropriate time. When the water temperature is below 18℃ and the shell length reaches more than 3.0cm, begin dividing seedlings. Divide and sort twice a year, in late autumn and early spring, with the sorting operation carried out on the raft frame. Use pointed steel pliers to remove attachments such as oysters and barnacles, and classify according to individual abalone specifications so that abalone seedlings in the same layer are uniform in size. The stocking density of abalone seedlings depends on the specification. For abalone with shell lengths of 2.5cm, 3.0cm, 3.5cm, 5.0cm, 6.0cm and 7.0cm, each layer is loaded with 60, 45, 35, 25, 20 and 15 individuals respectively.
3. Daily management
Check the feeding condition of the abalone, adjust the feeding amount in time, and keep records; frequently check for and remove predators and foreign matter around the abalone cages; observe the activity of the abalone during feeding, and if abnormal or dead abalone are found, identify the cause and take corresponding measures; regularly test water quality indicators such as water temperature, salinity, ph, dissolved oxygen and ammonia nitrogen, and keep records; frequently check whether the abalone cages and racks are firm and safe, and prevent abalone escape caused by the small doors of the abalone cages not being closed tightly.
4. Disease prevention and control
Adhere to prevention as the main approach. When selecting the farming sea area, choose as far as possible a sea area away from pollution, with smooth tidal currents and good water quality; strengthen farming management: maintain an appropriate farming density.
Requirements for sea hanging culture of abalone:
Farming environment
The farming area is selected in the Gangyu sea area of Lianjiang, an area with no pollution sources around it, water quality meeting fishery water quality standards, smooth tidal currents and convenient transportation. Its physicochemical factors are as follows: water depth reaches more than 10m, water flow 0.5m/s to 1.0m/s, water temperature 11℃ to 28℃, salinity 30‰ to 34‰, dissolved oxygen above 4mg/l, ammonia nitrogen ≤100mg/l, ph7.4 to 8.6.
Farming facilities
The main farming facilities are multi-layer abalone culture cages and frames. The abalone culture cage is a plastic box made of dark polyethylene or non-toxic polyvinyl chloride, divided into six layers, with each layer measuring 40cm×30cm×13cm. The frame is similar to the frame of a small sea cage for marine fish culture, with a specification of 2.5m×3.6m, with 10 frames as one unit (platform), and every three platforms connected to each other by used tires to form one area. The frame material is pine wood, and 15 foam floats with a buoyancy of 75kg each are used around each frame.