Method for artificially cultivating soft-shell crabs

Abstract

The present invention provides a method for artificially cultivating soft-shell crabs, wherein the method comprises adjusting the bicarbonate ion HCO3 in the aquaculture water when cultivating the soft-shell crabs. ‑ The concentration of calcium ions Ca in the aquaculture water is 400±20 mg / L; further, the method of the present invention controls the calcium ions Ca in the aquaculture water during the aquaculture period. 2+ The concentration is not less than 120mg / L; control the magnesium ion Mg in the aquaculture water 2+ Concentration not less than 200mg / L; potassium ion K + The concentration is not less than 100 mg / L; the total hardness of the aquaculture water is controlled to be not less than 800 mg / L; the pH of the aquaculture water is controlled to be 7.8-8.6. The method of the present invention is to adjust the bicarbonate ion HCO3 in the water ‑ The concentration of the salt causes the hardened crab shells to soften and become soft-shell crabs without molting, thus increasing the economic benefits of aquaculture.

Description

Technical Field

[0001] The invention belongs to the technical field of crab breeding, and particularly relates to a method for artificially breeding soft-shell crabs. Background Art

[0002] The mud crab (Scylla paramamosain) belongs to the phylum Arthropoda, class Malacca, order Decapoda, family Portunidae, and genus Scylla. It is primarily found in the coastal waters of Zhejiang, Fujian, Hainan, Guangdong, Guangxi, and Taiwan. It prefers to inhabit muddy gullies such as mangroves, intertidal zones, and river estuaries. It is a euryhaline, eurythermal, and warm-water crustacean. Its meat is delicious and highly nutritious, earning it the reputation of "sea ginseng," making it a popular seafood. In addition to its high nutritional value, nourishing properties, and sweet texture, mud crabs also boast a short breeding cycle, strong adaptability, rapid growth, and ability to remain active out of water, making them an excellent species for artificial aquaculture.

[0003] Soft-shell crab meat is tender and fragrant, and the entire crab shell is edible. The nutrients in the crab shell include cyprocinin, cytochrome, chitin, chitosan, calcium carbonate, and protein. Chitosan's health benefits include: ① regulating acidity and excreting toxins and heavy metals; ② moisturizing the intestines and promoting bowel movements, reducing the absorption of harmful intestinal substances; ③ lowering cholesterol and preventing diseases of civilization; ④ promoting weight loss and preventing cancer. Chitosan's health benefits include: ① antibacterial and immune-regulating effects; ② lowering cholesterol; ③ promoting cell activation and regulating blood pressure; ④ preventing and improving diabetes and inhibiting fat absorption. In short, soft-shell crab is nutritious and edible from head to toe. It contains 18 amino acids. Excluding water, every 100g of soft-shell crab contains 14.0g of protein, 2.5g of fat, 0.8g of carbohydrates, 14.2mg of zinc, 39.7mg of calcium, 2mg of phosphorus, 37mg of iron, 230 IU of vitamin A, and 0.0051g of riboflavin. The crab's muscle contains over 10 free amino acids, with glutamic acid, proline, and arginine being particularly high. Its soft shell is particularly rich in free calcium, which promotes growth and development in children, making it an excellent choice for enhancing height and intelligence. Currently, there is no direct method for preparing soft-shell crab by softening the shell. Summary of the Invention

[0004] In view of the gaps in the prior art, the present invention provides a method for artificially cultivating soft-shell crabs, thereby achieving artificial control of the process of the mud crab shell changing from hard to soft, thereby improving the preparation efficiency of soft-shell crabs.

[0005] The method for artificially cultivating soft-shell crabs provided by the present invention is to adjust the concentration of bicarbonate ions HCO3- in the aquaculture water to 400±20 mg / L when cultivating the soft-shell crabs.

[0006] The adjustment of the bicarbonate ion HCO3- concentration, as a specific description of the embodiment, is to add sodium bicarbonate (NaHCO3) to the aquaculture water;

[0007] Furthermore, the method of the present invention controls the calcium ion Ca in the aquaculture water during the aquaculture period. 2+ The concentration is not less than 120mg / L; control the magnesium ion Mg in the aquaculture water 2+ The concentration is not less than 200mg / L; potassium ion K + The concentration should not be less than 100 mg / L; the total hardness of the aquaculture water should be controlled to be not less than 800 mg / L; the pH of the aquaculture water should be controlled to be 7.8-8.6;

[0008] As a specific record of the embodiment, the HCO3- concentration is 398.76 mg / L; Ca 2+ The concentration is 118.96 mg / L; Mg 2+ The concentration is 228.74 mg / L; K + The concentration is 112.36 mg / L; the total alkalinity of the aquaculture water is 420.33 mg / L; the total hardness is 868.83 mg / L; and the pH is 8.0.

[0009] The method of the present invention, wherein the calcium ion Ca in the aquaculture water is controlled 2+ The concentration is achieved by adding calcium chloride (CaCl2); the magnesium ion Mg in the aquaculture water is controlled 2+ The concentration is achieved by adding magnesium chloride (MgCl2) and / or magnesium sulfate (MgSO4) to the aquaculture water; the potassium ion K in the aquaculture water is controlled. + The concentration is adjusted by adding potassium chloride (KCl) to the aquaculture water; the pH is adjusted by adding quicklime or sodium hydroxide to adjust the pH of the aquaculture water.

[0010] Furthermore, the method is to cultivate soft-shell crabs after desalination and domestication of mud crabs.

[0011] The method of the present invention adjusts the concentration of bicarbonate ions HCO3- in water, so that the hardened crab shells are softened to become soft-shell crabs without molting, thereby increasing the economic benefits of breeding. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 : Data chart of the results of cultivating soft-shell crabs in each canvas pond,

[0013] Figure 2 : Photos of some soft-shell crabs harvested Figure 1 ;

[0014] Figure 3 : Actual photos of cultivating earth pond;

[0015] Figure 4 : Photos of some soft-shell crabs harvested Figure 2 ;

[0016] Figure 5 : Data chart of the results of cultivating soft-shell crabs in earthen ponds. DETAILED DESCRIPTION

[0017] The applicant found in the aquaculture practice that in regulating the bicarbonate ion HCO3 in the aquaculture water - After the concentration reaches a certain level, the crab shells will gradually soften and become soft-shell crabs after a period of cultivation. The present invention is established on this basis.

[0018] The method of this aspect is to adjust the bicarbonate ion HCO3 in the aquaculture water - The concentration of bicarbonate ions HCO3 in the aquaculture water is adjusted - The concentration reaches about 400 mg / L;

[0019] To adjust the concentration of bicarbonate ions HCO3-, reagents commonly used in aquaculture for regulating bicarbonate ions can be used. In one embodiment of the present invention, sodium bicarbonate (NaHCO3) is added to the aquaculture water.

[0020] Furthermore, the method of the present invention controls the calcium ion Ca 2+ The concentration is not less than 120 mg / L, and the calcium ion regulating reagent commonly used in aquaculture is used. In one embodiment of the present invention, calcium chloride (CaCl2) is added to the aquaculture water; the magnesium ion Mg in the aquaculture water is controlled. 2+ The concentration is not less than 200 mg / L, and the magnesium ion is adjusted by a reagent commonly used in aquaculture. In one embodiment of the present invention, magnesium chloride (MgCl2) and / or magnesium sulfate (MgSO4) are added to the aquaculture water; potassium ions K + The concentration is not less than 100 mg / L, and potassium ion regulating reagents commonly used in aquaculture are used. In one embodiment of the present invention, potassium chloride (KCl) is specifically used; the total hardness of the aquaculture water is controlled to be not less than 800 mg / L, and the calcium ion Ca is adjusted by adding the above-mentioned 2+ and magnesium ions Mg 2+ The reagent changes the temporary hardness of the aquaculture water to adjust the total hardness of the aquaculture water; the pH of the aquaculture water is controlled at 7.8-8.6, and the pH is adjusted by quicklime and sodium hydroxide, which are commonly used to adjust the pH in aquaculture.

[0021] Among them, the method for determining the total hardness of water body, in the embodiment of the present invention, uses the water quality analysis box produced by Guangzhou Hankun Biotechnology Co., Ltd. to measure the total hardness.

[0022] The method for measuring the pH of water is to use a PHscan40 pen-type pH meter produced by Shanghai Bante Instruments Co., Ltd. (BanteInstruments) to measure the pH of water in the embodiment of the present invention.

[0023] The determination of HCO3 in water - ion method, in the embodiment of the present invention, a bicarbonate ion concentration meter PXS-HCO3 produced by Hangzhou Qiwei Co., Ltd. is used.

[0024] The method for measuring the pH of water is to use a PHscan40 pen-type pH meter produced by Shanghai Bante Instruments Co., Ltd. (BanteInstruments) to measure the pH of water in the embodiment of the present invention.

[0025] The present invention will be further described below with reference to the accompanying drawings and examples.

[0026] Example 1: Artificial cultivation of soft-shell crabs

[0027] Cultivation location: Hongxin Aquatic Products Company, Lianhua Township, Xizhou Town, Xiangshan County, Ningbo City, Zhejiang Province.

[0028] On July 10, 2023, the soft-shell crab (Scylla pseudoburrowing) was cultivated at Hongxin Aquatic Products in Lianhua Township, Xizhou Town, Xiangshan County, Ningbo City, Zhejiang Province. First, a canvas pond was built in the factory, followed by various preparations for cultivation.

[0029] Water quality control is required before cultivation. Water quality control is done by adding HCO3 to the aquaculture water. - , Ca 2+ Mg 2+ and K + Plasma. By adding reagents such as sodium bicarbonate, calcium chloride, magnesium chloride, potassium chloride and magnesium sulfate, HCO3 - The concentration is 398.76 mg / L; Ca 2+ The concentration is 118.96 mg / L; Mg 2+ The concentration is 228.74 mg / L; K + The concentration is 112.36 mg / L; the total alkalinity of the aquaculture water is 420.33 mg / L; the total hardness is 868.83 mg / L; and the pH is 8.0.

[0030] After adjusting the water quality, the cultivation of mud crabs is carried out. Select adult mud crabs with complete appearance, strong physique and good growth vitality, transport them to the breeding plant and release them into the canvas pond. Desalinate the mud crabs before release. The initial salinity of the mud crabs is 22‰. After the mud crabs have adapted to the 22‰ salinity water for a period of time (to eliminate the impact of the transportation process on the mud crabs), desalination begins. Place the mud crabs in the prepared 18‰ water for 8 hours. Thereafter, desalinate by 3‰ every 8 hours. When it is desalinated to 6‰, desalinate by 1‰ every 12 hours until the mud crabs can adapt to the salinity of 3‰.

[0031] The canvas ponds used for breeding are 1.5m long, 0.8m wide, and 0.8m high, with a total of 20 ponds. Each pond is stocked with 20 mud crabs. Each pond is equipped with oxygenation equipment and a circulating water system. Clams or razor clams are fed daily in the morning and evening, and any remaining bait is removed two hours after feeding. Inspections are conducted several times daily, focusing on the mud crab breeding process. The water is changed every three days, with half the water replaced each time.

[0032] After 14 days of cultivation, the crab shells began to soften gradually. After 20 days, all the surviving blue crabs had become soft-shell crabs, with a survival rate of 70%-80%. Figure 1 ), the weight of the cultivated blue crabs was 232.4±10g, and the weight of the harvested blue crabs was 248.8±10g. A total of 400 blue crabs were cultivated, and 297 soft-shell crabs were finally harvested ( Figure 2 ), the crab shell softening rate is 100%.

[0033] Example 2 Artificial cultivation of soft-shell crabs

[0034] Breeding location: Green Orchard Family Farm, Ruian City, Wenzhou City, Zhejiang Province ( Figure 3 )

[0035] On August 5, 2023, soft-shell crabs were cultivated at Green Orchard Family Farm in Ruian City, Wenzhou City, Zhejiang Province. Before being released, the concentration of bicarbonate HCO3- ions in the water was 80.76 mg / L, and the potassium K + The ion concentration is 53.16 mg / L, calcium Ca 2+ The ion concentration is 221.58 mg / L, magnesium Mg 2+ The ion concentration is 124.17 mg / L, the total alkalinity is 103.22 mg / L, the total water hardness is 760.14 mg / L, and the pH is 7.6.

[0036] Water quality control is required before cultivation. Water quality control is achieved by adding HCO3-, Mg 2+ and K + Plasma. By adding reagents such as sodium bicarbonate, magnesium chloride, potassium chloride and magnesium sulfate, the HCO3- concentration is 403.48 mg / L; Mg2+ The concentration is 412.44 mg / L; K + The concentration is 110.971 mg / L; the total alkalinity of the aquaculture water is 420.24 mg / L; the total hardness is 858.38 mg / L; and the pH is 8.0.

[0037] About 300 adult mud crabs are stocked per acre of water, totaling about 900 adult mud crabs.

[0038] Desalination is performed on the mud crabs before stocking. The initial salinity is 22‰. After the crabs have adapted to the 22‰ salinity water for a period of time (to eliminate the effects of transportation on the crabs), desalination begins. The crabs are placed in the prepared 18‰ water for 8 hours. Thereafter, the water is desalinated by 3‰ every 8 hours. Once the water reaches 6‰, the water is desalinated by 1‰ every 12 hours until the crabs are acclimated to a salinity of 3‰.

[0039] Approximately 300 adult mud crabs are stocked per acre of water, covering a total of three acres. The total number of adult mud crabs released is approximately 900. Two aerators are installed per acre, and the crabs are fed with fish or snail meat at designated locations and times each morning and evening. Inspections are conducted several times daily to monitor the progress of the mud crab cultivation.

[0040] The cultivated soft-shell crabs were harvested on August 26, 2023, after a cultivation period of approximately 20 days. The weight of the blue crabs before release was 284.7 ± 20 g, and the weight of the harvested soft-shell crabs was 298.6 ± 20 g. A total of 536 soft-shell crabs were captured ( Figure 4 ), the soft shell crab harvest rate is above 50% ( Figure 5 ), which also shows that as long as the blue crab can adapt to the water environment and survive, its crab shell can become soft, and the crab shell softening rate is 100%, which greatly improves the economic benefits.

Claims

1. A method for cultivating soft-shell crabs, characterized in that: The method comprises the following steps: cultivating mud crabs; during the cultivation period, adding sodium bicarbonate to the cultivation water to adjust the bicarbonate ion concentration, and adjusting the bicarbonate ion concentration of the cultivation water to 400±20 mg / L; controlling the calcium ion concentration of the cultivation water to be no less than 120 mg / L; the magnesium ion concentration to be no less than 200 mg / L; and the potassium ion concentration to be no less than 100 mg / L; controlling the total hardness of the cultivation water to be no less than 800 mg / L; and maintaining the pH of the cultivation water at 7.8-8.6; The calcium ion concentration in the aquaculture water is controlled by adding calcium chloride; the magnesium ion concentration in the aquaculture water is controlled by adding magnesium chloride and / or magnesium sulfate; the potassium ion concentration in the aquaculture water is controlled by adding potassium chloride; After the mud crab is desalinated and domesticated, it is cultivated into a soft-shell crab. By adjusting the concentration of bicarbonate ions in the water, the hardened crab shell becomes soft without molting and becomes a soft-shell crab.

2. The method according to claim 1, wherein The method is to control the bicarbonate ion concentration in the aquaculture water to 398.76 mg / L; the calcium ion concentration to 118.96 mg / L; the magnesium ion concentration to 228.74 mg / L; the potassium ion concentration to 112.36 mg / L; the total alkalinity of the aquaculture water to 420.33 mg / L; the total hardness to 868.83 mg / L; and the pH to 8.

0.

3. The method according to claim 1, wherein The pH of the aquaculture water is adjusted by adding quicklime or sodium hydroxide.

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