What kind of environment is suitable for abalone to grow in
Abalone is fairly widely distributed, while the Pacific abalone (Haliotis discus hannai) is mainly produced in the Yellow Sea and Bohai Sea and is a type of abalone with relatively high economic value. It has the habit of preferring clear water quality, abundant seaweed and smooth-flowing water in stone crevices. Let us now take a look at the growing environment and growth cycle of abalone!
The growing environment of abalone
1. Abalone lives in rocky reef zones with swift currents and luxuriant seaweed, and coastal islands or rocky points jutting out from the coast are all places they like to inhabit. Abalone mostly crawl and cling in the crevices of reefs or in stone caves. The water depth at which they are distributed varies with species; for example, the Pacific abalone in northern China is generally distributed at a water depth of more than ten meters, and in winter it moves to deeper places to avoid the cold, reaching a depth of 30 m. In spring it gradually moves upward, and some can live several meters below the low tide line; small abalone can even be collected near the low tide line.
2. Abalone likes to hide by day and come out at night. Abalone kept in ponds generally stay still and hidden during the day, and as soon as it gets dark they slowly become active. They are especially most active after 10 o'clock until before 3 o'clock in the latter half of the night, when their head and foot all stretch out, the tentacles on the cracks of the mantle extend from the shell holes, and they crawl on the bottom or walls of the pond. Their crawling speed can reach 50 cm per minute. Abalone also has the habit of returning to its nest; they often like to live in caves, go out at night to forage, and return to live in the cave when dawn is near.
3. Abalone likes to eat brown algae or red algae; for example, the Pacific abalone very much likes to eat wakame, tender kelp and sargassum. For abalone raised in ponds, each one can eat several tens of grams of small kelp per day. The food intake of abalone varies with the season; generally they eat more in seasons with higher water temperature, and in winter they are less active and eat less. When people put kelp into the pond where abalone are raised, although the abalone's head is retracted in the shell, relying on its relatively sensitive sense of smell, it can quickly detect the direction of the food and crawl toward the kelp. When the food is still some distance from its body, it can extend the two lobes at the front end of the lower foot, and in a clasping posture pull the food toward its mouth, and extend its disc-like proboscis to lick and eat with its radula. Kelp that has been eaten by them often leaves large semicircular holes with toothed patterns along the edges.
The growth cycle of abalone
The growth of abalone is a relatively slow type among the shellfish family. From a fertilized egg, growing to the commercial size of 6-8 cm usually takes 1-4 years or even longer. Taking China's Pacific abalone as an example, it takes about nearly 3 years of growth to reach about 7 cm.
The growth rate of abalone shows a downward trend with increasing age. During growth, the abalone shell leaves growth lines similar to tree rings. Whether the growth lines are obvious or not is related to the season of its environment and the type of feed it ingests. In seasons of rapid growth, the growth lines are obvious and relatively widely spaced. In seasons of slow growth, the opposite is true: the growth lines are dense and relatively close together. Sometimes it is not easy to directly judge the exact age of an abalone from the growth lines on the front of the shell. We can clean off the miscellaneous algae, calcareous tube worms and other objects attached to the shell surface, and use electric light to see through the abalone shell and observe their rings.
The farming conditions for abalone
The most suitable water temperature for abalone growth is 10-20°C. Taking Fujian's main abalone variety, the black abalone, as an example, when the temperature reaches 26-29°C, growth becomes slow, and below 14°C it stops growing. Therefore, in winter farmers send abalone to the south to be raised, and in summer farmers in the south send abalone to the north to escape the heat. Farming techniques There are many ways to raise abalone, including bottom sowing culture (also called natural proliferation), raft-type cage culture, and industrial farming and tunnel farming, etc. No matter which farming method is used, choosing fresh water quality is especially important.
1. Seaweed reproduces and feed is abundant.
2. Sea areas with clear and smooth-flowing water and stable seawater specific gravity, maintained above 1.020 throughout the year.
3. The bottom substrate is rocky reef and stones.
4. Sea areas with no industrial pollution, few harmful organisms, and preferably no freezing in winter and no drifting ice in spring.