The key to high-yield abalone farming is selecting good seedlings

Abalone is ranked first among the "Eight Treasures"; its flavor is delicious, tender and tasty, and it is rich in nutrients. Analyzed as a dried product, it contains 40% protein, 33.7% glycogen, 0.9% fat, and also contains vitamins and other trace elements. Besides being eaten fresh, abalone meat can also be made into dry products for storage and various canned foods. Abalone has high economic value, and many farmers are interested in it, so how to farm abalone for high yield? Selecting good seedlings is the key.

I. Selection of abalone seedlings

First, observe whether the growth marks of the abalone seedlings and the luster of the shell are obvious, and choose seedlings with obvious shell luster. The seedling specifications should be uniform and consistent, generally with a length of 2 cm as suitable, and ensure that the edge of the shell has no obvious gaps. This type of abalone seedling has strong vitality and vigorous life force, and is suitable for artificial farming; second, observe the strength of the abalone seedling's attachment ability, and turn the abalone seedling over to observe its turning time to judge whether the abalone seedling's vitality is vigorous; finally, abalone seedlings should be purchased during the best growth period for abalone seedlings, and the purchased abalone seedlings need to undergo comprehensive disinfection before being put into the sea.

II. Artificial farming environment

For abalone farming, choose a sea area with smooth water depth, fresh and pollution-free water quality, no nearby rivers, abundant seaweed resources, and relatively stable seawater salinity at medium salinity. The seawater should not be too shallow; preferably the water depth can reach between 15 and 20 m. The survival water temperature range for abalone is between 1°C and 28°C, and the most suitable growth water temperature is 14°C to 22°C. Abalone is a marine organism of medium salinity, and the seawater salinity is required to be stable at 29‰ to 31‰ as suitable, with a minimum of not less than 27‰ and a maximum of not more than 36‰. Abalone likes smooth water flow, so choose sea areas with regular reciprocating currents, and the flow rate should preferably be 50 to 60 m per minute. Abalone prefers sea areas with a pH value between 8 and 8.4, dissolved oxygen of not less than 4 mg per liter, ammonia nitrogen not greater than 100 mg, and organic oxygen consumption below 0.5 to 1 mg.

The new-style abalone farming cage has specifications of 52×52 cm, a four-layer combined square tray cage with rounded corners; each layer can hold about 150 abalone with a shell length of more than 3 cm, and one cage with 4 layers can hold 600; the modified cage with specifications of 40 cm and 8 layers can hold 80 abalone seedlings with a shell length of more than 3 cm per layer, and one 8-layer modified cage can hold 640; the Japanese-style zipper multi-layer cage has specifications of 60 cm, and each layer can hold 200 abalone seedlings with a shell length of more than 3 cm, and one cage with 5 layers can hold 1,000 abalone seedlings. Taking spring seedling placement as an example, by mid-April of the following year, when the abalone grows to 4.5 to 5 cm, it is necessary to promptly divide the cages, measure, and thin the seedlings in time; the new-style abalone farming cage with 150 per layer can be thinned to 80 per layer; the modified cage with 80 per layer can be thinned to 50 per layer; the Japanese-style zipper multi-layer cage with 200 per layer can be thinned to 120 per layer.

III. Feeding management

For abalone seedlings newly placed into the farming sea area, seaweed is mainly used, and according to actual feeding needs, feed such as Gracilaria and Ulva can also be given to the abalone seedlings. At the same time, artificial feed should also be mixed in. During the three seasons from September to November, seaweed feed is generally relatively scarce, so at this time artificial feed is mainly used, and dried kelp can also be fully soaked and crushed before being fed to abalone. During the feeding process, if the feed given is mainly seaweed, then the feed amount should be appropriately increased to ensure that the abalone has sufficient feed to eat. Under normal circumstances, abalone seedlings are fed once every 4 to 6 days, and feed should be put in according to a ratio of 90 to 120% of the total amount of abalone, keeping residual feed between 15% and 20%. In the process of abalone feeding management, whether feed placement is scientific and whether the feeding amount is sufficient are key factors determining the growth speed and survival rate of abalone. Years of practical experience show that ensuring the freshness of feed is of great help in promoting healthy growth of abalone. Fresh feed can ensure the feeding quality of abalone, thereby better improving the disease resistance of abalone and increasing the survival quality of seedlings. In the specific feeding process, the feed amount should be scientifically adjusted according to the individual size of the abalone and the seawater temperature.

IV. Daily management

In daily management, frequently check the cage frames, wooden stakes, root ropes, hanging ropes, floats, and hanging stones. If rope tangling is found, it should be resolved promptly; especially before a typhoon comes, carefully check whether various abalone farming facilities are firm. Remove shellfish and miscellaneous algae and floating mud on the cage walls or inside the cages at any time, especially oysters, mussels, barnacles, sea squirts, bryozoans, and sea anemones attached to abalone shells. Most of these harmful organisms can attach to net cages and abalone shells, causing reduced water permeability of abalone cages, affecting the movement and growth of abalone, making it difficult for abalone to feed, and causing them to become thin and die. At present, prevention and manual removal are mainly adopted for these harmful organisms. Prevention is based on understanding their reproduction patterns to avoid their peak attachment period, and medicinal coatings can also be used for prevention and removal. Manual removal is to lightly strike the miscellaneous algae and shellfish on the abalone cages with a rubber rod; the rubber rod does not damage the net cage, and the remaining shellfish attached to the abalone shells that cannot be knocked off are cleaned with a small iron shovel. In addition, after each trip to sea, the floating mud inside the cages should be promptly cleaned to prevent death caused by floating mud blockage.

During abalone seedling rearing, feed is especially important and must be prepared in advance. Before larval collection, the collectors need to be pre-attached with benthic diatoms or placed in shallow culture ponds to soak for several days, and then these collectors with attached benthic diatoms and unicellular algae are moved into larval culture ponds to collect late umbo larvae. During the seedling rearing process, algae cultivation must be continuously strengthened. In addition to adding an appropriate amount of nutrients in the larval culture pond, lighting should also be strengthened to promote the reproduction speed of benthic diatoms, so that the number of benthic diatoms reproduced and the feeding amount of larvae or juvenile abalone remain balanced. Therefore, fertilizer needs to be continuously added. If the basic feed is insufficient, after changing the water, feed should be supplemented or feed plates should be replaced to meet the larval feed intake. Abalone feed is mainly kelp, wakame, and Ulva, followed by Sargassum, Sargassum thunbergii, brown algae, or red algae. Abalone farmed in shallow water areas can eat dozens of grams of small kelp per abalone per day. The food intake of abalone changes with the season; generally, they eat more in seasons with higher water temperatures. When feeding, first remove residual feed and wash away floating mud and attachments in the abalone cages to create a good environment for abalone growth. The feeding amount depends on the feeding situation of the abalone, generally 15% to 20% of abalone body weight. Feeding frequency is once every 8 days from March to April, once every 5 days from April to June, once every 7 days from June to July, once every 10 days from July to September, once every 7 days from September to December, and once every 15 days from December to March.

V. Disease prevention

Because abalone is farmed on the sea surface, medicinal control is difficult and costly. Therefore, during the feeding process, prevention is mainly adopted, by maintaining a good water quality environment, feeding fresh feed, and regularly checking the growth of abalone. Diseased abalone found should be isolated promptly, and comprehensive prevention and control measures should be used to improve the body resistance of abalone and ensure the economic benefits of farmers.