Five-scale net cage culture method of cobia

Abstract

The application provides a five-trout large-scale net cage breeding method, which selects breeding sea areas, configures net cage systems, releases fry, manages density, prepares feed, manages feed feeding, monitors water quality, regulates environment, carries out hierarchical screening and breeding cycle management, prevents diseases, manages health, and controls harvest and quality, etc., through scientific site selection, optimized net cage structure, precise feeding, phased density management, and comprehensive disease prevention and control, etc., so as to improve the survival rate of five-trout breeding, and reach commercial specifications (>=4 kg) in 18-24 months, thereby providing a technical scheme for the industrialized breeding of five-trout. The technical problems of low survival rate, slow growth, frequent diseases, and unstable breeding benefits in the prior art are solved, and the whole-cycle large-scale breeding of five-trout from breeding to commercial fish is realized.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology and relates to five yellowtail (Amberjack). Five-rayed amberjack The aquaculture technology specifically involves a method for large-scale cage culture of five yellowtail amberjack. Background Technology

[0002] Five Yellowtail ( Five-rayed amberjack The Japanese yellowtail (also known as the Japanese amberjack or yellowtail amberjack) is a migratory marine fish belonging to the order Perciformes, family Carangidae, and genus Amberjack. It is an important economic fish species, widely distributed in the Northwest Pacific Ocean. This fish has delicious flesh, rich in unsaturated fatty acids such as DHA and EPA, making it a high-end ingredient for sashimi. It enjoys a high reputation in sashimi, sushi, and other dishes, and has extremely high commercial value in Japan, South Korea, and the international market. It is an important high-end aquatic product in coastal areas of Japan, South Korea, and my country.

[0003] Although Japan has successfully bred amberjack in captivity, the number of juveniles produced cannot meet the demand for juvenile fish in aquaculture, and the high cost further limits the scale of cultivation. In recent years, coastal areas of Fujian, Guangdong, Liaoning, Shandong, and other provinces in my country have successively introduced and piloted the cultivation of amberjack. With the advancement of my country's deep-sea aquaculture strategy, amberjack has become one of the most promising aquaculture species in deep-sea cage culture. Currently, amberjack cultivation mainly relies on the collection of natural fry from the ocean for cage culture. From March to April, amberjack spawn in Chinese waters. Shortly after spawning, juveniles less than 15 mm in length are carried to the coast by the Kuroshio Current and captured by fine-mesh nets for artificial cultivation.

[0004] The current five net cage culture techniques for amberjack have the following problems: (1) The management of stocking density is extensive and the survival rate fluctuates greatly; (2) The feed formula is not precise enough and the feed conversion efficiency needs to be improved; (3) The disease prevention and control system is imperfect and diseases such as nodular disease and parasitic diseases occur frequently; (4) The monitoring of the breeding environment is insufficient and the risk of water quality deterioration is high; (5) There is a lack of systematic large-scale breeding technical regulations.

[0005] With the rapid development of China's marine aquaculture industry and the upgrading of consumption, the market demand for high-quality marine fish is increasing. As a high-quality cold-water marine fish, the yellowtail amberjack has excellent aquaculture potential in Chinese waters. Therefore, there is an urgent need to develop a large-scale cage culture technology for yellowtail amberjack suitable for the conditions of Chinese waters to promote the healthy development of this industry. Summary of the Invention

[0006] This invention addresses the aforementioned problems and aims to provide a five-striped yellowtail ( Five-rayed amberjackThe large-scale cage culture technology aims to solve the technical problems existing in the current technology, such as low survival rate, slow growth, frequent disease, and unstable breeding benefits, and realize the large-scale breeding of five yellowtail amberjack from breeding to marketable fish.

[0007] To achieve the above objectives, the present invention provides a method for large-scale cage culture of five-striped yellowtail, which, based on the differences in size and nutritional requirements of fish fry at different stages, as well as the differences in environmental conditions and disease types under different seasons, and combined with actual artificial breeding conditions, implements different breeding schemes at different stages, thereby realizing large-scale artificial cage culture of five-striped yellowtail.

[0008] This invention improves the survival rate of yellowtail amberjack through key technical aspects such as aquaculture area selection and cage system configuration, seedling stocking and density management, feed formulation and feeding management, water quality monitoring and environmental control, grading and screening and aquaculture cycle management, disease prevention and health management, and harvesting and quality control. By employing measures such as scientific site selection, optimized cage structure, precise feeding, phased density management, and comprehensive disease prevention and control, the survival rate of yellowtail amberjack can be improved, reaching marketable size (≥4kg) in 18-24 months. This provides a technical solution for the industrialized aquaculture of yellowtail amberjack. The specific technical solution to be protected is as follows:

[0009] The method for large-scale cage culture of five yellowtail amberjack provided by this invention includes the following steps:

[0010] (1) Selection of aquaculture sea area

[0011] Select aquaculture sites with a water depth of ≥15 m, a distance of ≥2 km from pollution sources, a current velocity of 0.2~0.5 m / s, a year-round water temperature of 15~30℃, a minimum winter water temperature of no less than 13℃, a year-round salinity of ≥16‰, a transparency of ≥3 m, dissolved oxygen of ≥3mg / L, and certain shelter from wind.

[0012] Preferably, the optimal water temperature for aquaculture sites is 20–29℃; the optimal salinity is 28–34‰, with a variation range of ≤±3‰; dissolved oxygen is ≥5mg / L; and the bottom of the net cage is ≥5m from the seabed.

[0013] Furthermore, select semi-open bays or island / reef waters with good tidal flow and shelter from wind as aquaculture sites, such as inner bays or sea areas with natural islands or other barriers.

[0014] (2) Selection of net cages

[0015] Choose aquaculture cages with high wind and wave resistance, and change the mesh size in stages as the fish grow to ensure sufficient water exchange and dissolved oxygen supply.

[0016] In a preferred embodiment of the present invention, the aquaculture cage is composed of a combination of high-density polyethylene or steel frame floats and ultra-high molecular weight polyethylene or nylon netting. High-density polyethylene or steel frame floats offer good stability, ensuring the cage remains relatively balanced and facilitating operation and management; however, steel frame floats require rust prevention treatment.

[0017] In terms of shape, circular floating cages or square deep-water cages are used.

[0018] In terms of cage specifications, there are three sizes: small, medium, and large, used for different types of seedling cultivation and aquaculture. Preferred sizes are: small cages (8×8×8 m ~ 10×10×8 m); medium cages (12×12×12 m ~ 18×24×12 m); and large cages (30×30×15 m ~ 50×50×50 m).

[0019] For anchoring, multi-point anchoring is adopted, and a quick-release cable device is provided to ensure stable positioning of the cages.

[0020] (3) Seedling release and management

[0021] Select healthy fry weighing 20-200 g with intact body surface, no abnormal behavior, and tested positive for pathogens. Implement a tiered rearing strategy during the breeding process: fry under 200g are raised in small near-shore net cages, fish of medium size (500-1200g) are transferred to medium-sized net cages, and adult fish over 1.2kg are transferred to large deep-water net cages. At the same time, control the stocking density based on different growth stages.

[0022] Regarding mesh size: 2-3 cm for juvenile fish, 4-5 cm for medium-sized fish, and 6-8 cm for adult fish.

[0023] The stocking densities for different growth stages during the aquaculture process are as follows: 14,000–20,000 fish / box for juveniles, 4,000–8,000 fish / box for intermediate-sized fish, and 10,000–25,000 fish / box for adult fish. The stocking density can be adjusted according to the size of the aquaculture cages.

[0024] (4) Feeding management

[0025] A fully formulated feed farming strategy was adopted to avoid the use of frozen miscellaneous fish, thereby reducing the risk of disease transmission and water pollution. Specialized feeds were formulated for each stage of the amberjack's growth, based on their nutritional needs at different stages.

[0026] Juvenile fish feed: crude protein ≥55%, crude fat 18-22%, DHA+EPA ≥3%, fed 4-6 times a day, with the daily feed amount accounting for 5-8% of the fish's body weight;

[0027] Intermediate growth stage feed: crude protein ≥52%, crude fat 20-25%, DHA+EPA ≥2%, fed 2-3 times a day, with the daily feed amount accounting for 3-5% of the fish's body weight;

[0028] Adult fish feed: crude protein ≥ 50%, crude fat 25-30%, feed 1-2 times a day, the daily feed amount accounts for 1.5-3% of the fish body weight, and the fat content of the feed should be appropriately increased 1-2 months before market launch.

[0029] Five-striped yellowtail is a highly carnivorous fish with a high protein requirement. The nutritional indicators of its formulated feed should meet the following requirements: crude protein 50-60%, crude fat 15-25%, n-3 HUFA ≥ 1.5%, carbohydrates < 15%, and vitamins / minerals added according to standards.

[0030] The feed type is selected from extruded feed or wet pellet feed. The pellet diameter is adjusted according to the different stages of the fish fry, as follows: 2-4 mm for juvenile fish, 4-8 mm for adult fish, and 8-15 mm for adult fish.

[0031] When feeding, the diameter of the feed should increase with the growth of the fish. The feeding frequency should be dynamically adjusted according to the water temperature: during the suitable temperature period of 20-28℃, feed normally; during the high temperature period of water temperature >30℃, reduce the amount of feed by 30-50% or stop feeding; during the low temperature period of water temperature <15℃, reduce the feeding frequency to once every 2-3 days or stop feeding to avoid indigestion; at the same time, implement a weekly rest system, selecting 1-2 days per week to stop feeding to promote full digestion of the fish, stimulate appetite, and reduce the water load. Avoid overfeeding to prevent feed waste and water quality deterioration.

[0032] (5) Aquaculture management

[0033] During the aquaculture process, water temperature, dissolved oxygen, and pH are continuously monitored, and ammonia nitrogen and nitrite are monitored at intervals (weekly) to keep them within a suitable range. At the same time, the net cages are cleaned regularly and antifouling treatment is carried out. During the aquaculture process, the focus is on preventing and controlling common bacterial diseases, viral diseases, and parasitic diseases in aquaculture. Every 1 to 2 months, a graded screening is carried out, and the fish are divided into three grades: large, medium, and small, according to their size, and then transferred to different net cages.

[0034] Preferably, the water temperature, dissolved oxygen, pH value, ammonia nitrogen, and nitrite are as follows: water temperature 20-29℃, dissolved oxygen ≥3 mg / L at any time, pH value 7.5-8.5, and ammonia nitrogen <0.5 mg / L;

[0035] During cage maintenance, remove organisms attached to the netting every 3-4 weeks in summer and every 6-8 weeks in winter, and regularly observe the wear and tear of the netting, and carry out anti-fouling treatment according to the degree of pollution.

[0036] When controlling diseases, a biosafety system based on prevention and comprehensive control should be established, focusing on the prevention and control of common bacterial diseases (alpha-hemolytic streptococcal disease, pseudotuberculosis, vibriosis), viral diseases (iridovirus disease), and parasitic diseases (Benedeniasis, etc.) in aquaculture. The control measures adopted are as follows:

[0037] (a) Immune enhancement: Silkrose, β-glucan, vitamin C and E are added to the feed;

[0038] (b) Probiotic application: Apply 15-30 ppm of heat-inactivated Lactobacillus plantarum L-137;

[0039] (c) Parasite control: Regularly monitor for parasites; treat severe infections with freshwater baths.

[0040] (d) Environmental management: When the water temperature is >28℃, strengthen monitoring and appropriately reduce the stocking density;

[0041] (e) Dead fish should be removed promptly to prevent the spread of disease.

[0042] (6) Breeding cycle and harvest

[0043] Seedlings are released in April or May each year, with a rearing cycle of 18 to 24 months until they reach marketable size (≥4 kg). Harvest when the fat content is 8 to 12%. Stop feeding 48 to 72 hours before harvest. The optimal harvesting period is from October to March of the following year, when fat accumulation is at its peak.

[0044] Compared with the prior art, the beneficial effects of this application are as follows:

[0045] This invention, through scientific site selection (water temperature 20-29℃, salinity 30-36‰, dissolved oxygen ≥5 mg / L), optimized cage structure (size 10×10×10 m to 50×50×50 m), precise feeding (protein content of compound feed 50-60%), phased density management (14,000-20,000 fish / cage during the juvenile stage, 3,500-5,000 fish / cage during the commercial stage), and comprehensive disease prevention and control measures, allows the fish to reach marketable size (≥4 kg) in 18-24 months. The survival rate of five-spotted yellowtail is as high as 97%, solving the technical problems of low survival rate, slow growth, frequent disease, and unstable farming benefits in existing technologies, and realizing large-scale farming of five-spotted yellowtail from breeding to marketable fish.

[0046] Furthermore, this invention establishes clear technical parameters and operating procedures, and its technical solution is scientific and systematic, highly reproducible, and easy to promote and apply in production. Detailed Implementation

[0047] To make the inventive objectives, technical solutions, and beneficial effects of this application clearer, the following description, in conjunction with embodiments, further illustrates this application. It should be understood that the embodiments described are for illustrative purposes only and are not intended to limit the scope of the application. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this description.

[0048] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0049] The present invention is further illustrated below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. The processes, conditions, experimental methods, etc., for implementing the present invention, except as specifically mentioned below, are all common knowledge and general knowledge in the art, and the present invention does not have any particular limitations.

[0050] This invention mainly focuses on several aspects, including the selection of aquaculture areas and configuration of cage systems, stocking and density management of seedlings, feed formulation and feeding management, water quality monitoring and environmental control, disease prevention and health management, grading and screening and aquaculture cycle management, and harvesting and quality control, as detailed below:

[0051] 1. Selection of aquaculture areas and configuration of cage systems

[0052] 1.1 Criteria for Selecting Sea Areas

[0053] Five yellowtail amberjack were cultured in deep-water, wave-resistant net cages. Cage site selection requirements: water depth ≥ 15 m, distance from pollution sources ≥ 2 km, ocean current velocity 0.2–0.5 m / s, year-round water temperature maintained within the range of 15–30 ℃, minimum winter water temperature not lower than 13 ℃, salinity maintained above 16‰ year-round (optimal 28–34‰), transparency ≥ 3 m, dissolved oxygen ≥ 5 mg / L. Preferred locations were semi-open bays or island / reef waters with good tidal flow and shelter from wind. Specific selection parameters for the aquaculture area are shown in Table 1 below.

[0054] Table 1. Indicators for Selecting Aquaculture Areas

[0055]

[0056] 1.2 Configuration of the cage system

[0057] The net cage structure uses a combination of steel structure / high-density polyethylene (HDPE) floats + ultra-high molecular weight polyethylene (UHMWPE) / nylon netting. The size of the rearing net cages can be either round floating / sinking net cages or square deep-water net cages. The mesh size is changed in stages as the fish grow to ensure sufficient water exchange and dissolved oxygen supply. The net cage structure configuration is shown in Table 2 below:

[0058] Table 2 Summary of Configuration Parameters for Net Cage System

[0059]

[0060] 2. Seedling stocking and density management

[0061] 2.1 Seedling Quality Standards

[0062] Select healthy, undamaged seedlings without abnormal behavior as breeding stock. Specific selection criteria are shown in Table 3 below:

[0063] Table 3 Seedling Selection Criteria

[0064]

[0065] 2.2 Stocking Density Management

[0066] A tiered rearing strategy was implemented: fingerlings (under 200g) were raised in small nearshore cages (8×8×8 m); intermediate-sized fish (500–1200g) were transferred to medium-sized cages (12×12×8 m); and adult fish (over 1.2kg) were transferred to large deep-water cages. Stocking densities also varied across different growth stages, as detailed in Table 4 below.

[0067] Table 4 Summary of Stocking Density Management Methods

[0068]

[0069] 3. Feed preparation and feeding management

[0070] 3.1 Feed Formulation

[0071] This invention employs a fully formulated feed farming strategy, avoiding the use of frozen miscellaneous fish to reduce the risk of disease transmission and water pollution. Specialized feeds are formulated for each stage of the amberjack's growth, based on their nutritional needs:

[0072] (1) Juvenile fish feed (body weight <100 g): crude protein ≥55%, crude fat 18-22%, DHA+EPA ≥3%, feed 4-6 times a day, and the daily feed amount accounts for 5-8% of the fish body weight.

[0073] (2) Feed during the growth period (500-1000 g): crude protein ≥52%, crude fat 20-25%, DHA+EPA ≥2%, feed 2-3 times a day, and the daily feed amount accounts for 3-5% of the fish's body weight.

[0074] (3) Adult fish feed (body weight > 1000g): crude protein ≥ 50%, crude fat 25-30%, feed 1-2 times a day, the daily feed amount accounts for 1.5-3% of the fish body weight. 1-2 months before market launch, the fat content of the feed can be appropriately increased (to 30-35%) to increase fat deposition in the fish body and improve the quality of commercial fish.

[0075] The five-striped yellowtail is a highly carnivorous fish with a high protein requirement. The nutritional indicators of its formulated feed are shown in Table 5 below:

[0076] Table 5 Nutritional Indicators of Compound Feed for Five-striped Yellowtail

[0077]

[0078] 3.2 Feed Type

[0079] (1) Extruded feed: It is produced by extrusion process. The pellets contain micropores and can be filled with a higher proportion of oil. After entering the water, it floats first and then sinks slowly. It has a high feeding rate and low water pollution.

[0080] (2) Wet pellet feed: It is made by mixing fresh fish paste with compound feed. It has good palatability, but a short shelf life.

[0081] (3) Particle diameter: 2-4 mm for juvenile fish, 4-8 mm for medium-sized fish, and 8-15 mm for adult fish.

[0082] 3.3 Feeding Management

[0083] Feeding frequency should be dynamically adjusted according to water temperature: During the suitable temperature period (20-28℃), feed normally; during the high temperature period (water temperature >30℃), reduce the amount of feed by 30-50% or stop feeding to avoid indigestion; during the low temperature period (water temperature <15℃), reduce the feeding frequency to once every 2-3 days or stop feeding altogether. Implement a weekly rest system: Select 1-2 days per week to stop feeding to promote full digestion of the fish, stimulate their appetite, and reduce the water load, avoiding overfeeding that leads to feed waste and water quality deterioration. See Table 6 below for details:

[0084] Table 6 Summary of Feeding Method Management

[0085]

[0086] 4. Water quality monitoring and environmental control

[0087] 4.1 Water quality monitoring indicators

[0088] The main parameters monitored are water temperature, dissolved oxygen, pH, ammonia nitrogen, and nitrite. The monitoring frequency and parameters are shown in Table 7 below.

[0089] Table 7 Water Quality Monitoring Indicators

[0090]

[0091] 4.2 Cage Maintenance

[0092] Regular maintenance of the net cages is required during the aquaculture process. Please refer to Table 8 below for details:

[0093] Table 8 Summary of Cage Maintenance Project Information

[0094]

[0095] 5. Disease prevention and health management

[0096] 5.1 Main Disease Types

[0097] Establish a biosafety system that prioritizes prevention and integrates comprehensive control measures, focusing on the prevention and control of common bacterial, viral, and parasitic diseases in amberjack farming. The main diseases in amberjack farming are listed in Table 9 below, including:

[0098] Table 9. Major Disease Types and Symptoms of Five-Striped Yellowtail

[0099]

[0100] 5.2 Comprehensive Prevention and Control Measures

[0101] Disease prevention and control adopts a multi-pronged approach, as detailed in Table 10 below:

[0102] Table 10 Disease Prevention and Control Measures

[0103]

[0104] 6. Grading and Screening and Breeding Cycle Management

[0105] 6.1 Hierarchical Screening

[0106] During the aquaculture process, the fish fry are regularly graded and screened, and fish of different sizes are placed in net cages of different sizes. The operation method is shown in Table 11 below:

[0107] Table 11 Key Points of Tiered Screening Operation

[0108]

[0109] 6.2 Breeding Cycle

[0110] Please refer to Table 12 below for details:

[0111] Table 12 Five Yellowtail Farming Cycles

[0112]

[0113] 7. Harvesting and Quality Control

[0114] 7.1 Harvest Standards

[0115] Please refer to Table 13 below for details:

[0116] Table 13 Harvesting Standards for Five-Striped Yellowtail

[0117]

[0118] 7.2 Harvest Management

[0119] The slaughtering and transportation methods at harvest are shown in Table 14 below:

[0120] Table 14 Harvesting Management of Five-Striped Yellowtail

[0121]

[0122] Based on the above method, this invention has been used to conduct standard-sized and large-scale cage culture of five-lined yellowtail in different sea areas, with extremely high survival rates, as detailed below:

[0123] Example 1: Standard-scale cage aquaculture

[0124] 1. Aquaculture site: Sandu Bay, Ningde, Fujian Province. The average annual water temperature is 13-28 ℃, the lowest water temperature in winter is 12 ℃, the highest water temperature in summer is 29 ℃, the salinity is 25-33‰, the water depth is 18-25 m, and the current velocity is 0.3-0.4 m / s.

[0125] 2. Cage configuration: The cage has 5 openings with an HDPE frame structure, measuring 8×8×8 m (adjusted to 12×12×8 m during the mid-fishing period), covered with nylon netting, and has a mesh size of 4 cm (adjusted to 6 cm during the mid-fishing period).

[0126] 3. Seedling release: In early May, release healthy seedlings weighing 50-80 g, with 5,000 seedlings per box, for a total of 25,000 seedlings.

[0127] 4. Feeding: Use formulated feed (55% crude protein, 18% crude fat). Initially, the daily feed amount is 6% of the fish's body weight, divided into 4 feedings. Gradually adjust as the fish grows, with the daily feed amount for adult fish being 3% of their body weight, fed twice a day. Do not feed on Sundays.

[0128] 5. Breeding Management: Measure body length and weight and grade the animals monthly; add silk polysaccharide (0.2%) to the feed regularly from July to August to prevent parasitic diseases; clean the netting every two weeks.

[0129] 6. Breeding results: The average weight reached 1.8 kg at the end of the first year; the average weight reached 4.2 kg in October of the second year, with a survival rate of 96.5% and a feed conversion ratio of 2.1.

[0130] Example 2: High-efficiency aquaculture in large net cages

[0131] 1. Aquaculture site: Zhelang sea area, Shanwei, Guangdong Province, with an average annual water temperature of 16-28 ℃, salinity of 32-35‰, water depth of 25-35 m, and current velocity of 0.3-0.5 m / s.

[0132] 2. Cage configuration: The cage is a large HDPE frame cage with 5 openings, measuring 30×30×15 m, and equipped with an automatic settling device.

[0133] 3. Seedling release: At the end of April, seedlings weighing 100-150 g are released, with 25,000 seedlings released per box, for a total of 125,000 seedlings.

[0134] 4. Feeding: High-energy compound feed (52% crude protein, 22% crude fat) is used, and an automatic feeding system is employed on the feeding vessel. Feed three times a day in summer and once a day in winter.

[0135] 5. Special Management: Install an underwater stereo camera monitoring system to monitor the fish's status and feeding behavior in real time and optimize feeding strategies; during typhoon season, use a sinking device to lower the net cages to 8 m below the water surface.

[0136] 6. Aquaculture Results: The average weight reached 2.2 kg at the end of the first year; the average weight reached 4.8 kg in November of the second year, with a survival rate of 97.2% and a feed conversion ratio of 1.9. Due to the larger net cages providing more space for movement, the farmed fish had firm muscles and excellent quality.

[0137] The undescribed parts of this invention are the same as or implemented using existing technology. The applicant declares that this invention is illustrated through the above specific embodiments, but the invention is not limited to the above detailed methods, i.e., it does not mean that the invention must rely on the above detailed methods to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A method for large-scale cage culture of five-lined yellowtail amberjack, characterized in that, Includes the following steps: (1) Selection of aquaculture sea area Select aquaculture sites with a water depth of ≥15 m, a distance of ≥2 km from pollution sources, a current velocity of 0.2~0.5 m / s, a year-round water temperature of 15~30℃, a minimum winter water temperature of no less than 13℃, a year-round salinity of ≥16‰, a transparency of ≥3 m, dissolved oxygen of ≥3mg / L, and certain shelter from wind. (2) Selection of net cages Choose aquaculture cages with high wind and wave resistance, and change the mesh size in stages as the fish grow to ensure sufficient water exchange and dissolved oxygen supply; (3) Seedling release and management Select seedlings weighing 20–200 g, with intact and undamaged bodies, no abnormal behavior, and healthy after pathogen testing. For seedlings; a tiered rearing strategy is implemented during the breeding process: juvenile fish under 200g are raised in small near-shore net cages, fish of medium size (500-1200g) are transferred to medium-sized net cages, and adult fish over 1.2kg are transferred to large deep-water net cages. At the same time, the stocking density is controlled based on different growth stages. (4) Feeding management A fully formulated feed farming strategy was adopted to avoid the use of frozen miscellaneous fish, thereby reducing the risk of disease transmission and water pollution. Specialized feeds were formulated for each stage of the amberjack's growth, based on their nutritional needs at different stages. Juvenile fish feed: crude protein ≥ 55%, crude fat 18-22%, DHA+EPA ≥ 3%, fed 4-6 times a day. Daily feeding amount is 5-8% of the fish's body weight; Intermediate growth stage feed: crude protein ≥52%, crude fat 20-25%, DHA+EPA ≥2%, fed 2-3 times a day, with the daily feed amount accounting for 3-5% of the fish's body weight; Adult fish feed: crude protein ≥50%, crude fat 25-30%, fed 1-2 times a day, with a daily feed amount accounting for 1.5-3% of the fish's body weight. 1-2 months before market launch, the fat content of the feed should be appropriately increased. When feeding, the diameter of the feed should increase with the growth of the fish. The feeding frequency should be dynamically adjusted according to the water temperature: normal feeding during the suitable temperature period of 20-28℃, reduced feeding amount during the high temperature period of water temperature >30℃, and reduced feeding frequency during the low temperature period of water temperature <15℃. At the same time, a weekly rest system should be implemented, and feeding should be stopped for 1-2 days each week. (5) Aquaculture management During the aquaculture process, water temperature, dissolved oxygen, and pH are continuously monitored, while ammonia nitrogen and nitrite are monitored intermittently to maintain optimal levels. Within a suitable range; at the same time, the net cages should be cleaned regularly and anti-fouling treatment should be carried out; during the breeding process, the focus should be on preventing and controlling common bacterial diseases, viral diseases and parasitic diseases in aquaculture; grading and screening should be carried out every 1 to 2 months; (6) Breeding cycle and harvest Seedlings are released in April or May each year, and the breeding cycle is 18 to 24 months until they reach marketable size; they are harvested when the fat content is 8 to 12%.

2. The method for large-scale cage culture of five yellowtail amberjacks according to claim 1, characterized in that, In step (1), a semi-open bay or island / reef waters with good tidal flow and shelter from wind are selected as aquaculture sites. The optimal water temperature for aquaculture sites is 20–29℃; the optimal salinity is 28–34‰ with a variation range of ≤±3‰; dissolved oxygen is ≥5mg / L; and the bottom of the net cage is ≥5m from the seabed.

3. The method for large-scale cage culture of five yellowtail amberjacks according to claim 1, characterized in that, In step (2), the aquaculture cage is made of high-density polyethylene or steel frame floating frame combined with ultra-high molecular weight polyethylene or nylon netting, and the shape is a circular floating cage or a square deep-water cage.

4. The method for large-scale cage culture of five yellowtail amberjacks according to claim 3, characterized in that, Small wire mesh cages range from 8×8×8 m to 10×10×8 m; medium-sized wire mesh cages range from 12×12×12 m to 18×24×12 m; large wire mesh cages range from 30×30×15 m to 50×50×50 m. Mesh size: 2-3 cm for juvenile fish, 4-5 cm for medium-sized fish, and 6-8 cm for adult fish.

5. The method for large-scale cage culture of five yellowtail amberjacks according to claim 4, characterized in that, In step (3), the stocking density at different growth stages during the breeding process is as follows: 14,000 to 20,000 fish / box for juvenile stage, 4,000 to 8,000 fish / box for intermediate size breeding stage, and 10,000 to 25,000 fish / box for adult stage.

6. The method for large-scale cage culture of five yellowtail amberjacks according to claim 1, characterized in that, In step (4), the feed type is selected from extruded feed or wet pellet feed, and the pellet diameter is as follows: 2-4 mm for juvenile fish, 4-8 mm for adult fish, and 8-15 mm for adult fish. Regarding feeding frequency, reduce the amount of feed by 30-50% or stop feeding during periods of high temperature; reduce the feeding frequency to once every 2-3 days or stop feeding during periods of low temperature.

7. The method for large-scale cage culture of five yellowtail amberjacks according to claim 1, characterized in that, In step (5), the parameters for water temperature, dissolved oxygen, pH, ammonia nitrogen, and nitrite are as follows: water temperature 20–29℃, dissolved oxygen ≥3 mg / L at any time, pH 7.5–8.5, and ammonia nitrogen <0.5 mg / L. During cage maintenance, remove organisms attached to the netting every 3-4 weeks in summer and every 6-8 weeks in winter, and regularly observe the wear and tear of the netting, and carry out anti-fouling treatment according to the degree of pollution.

8. The method for large-scale cage culture of five yellowtail amberjacks according to claim 1, characterized in that, In step (5), the methods for disease prevention and control are as follows: (1) Enhance immunity by adding silk rose, β-glucan, vitamin C and E to the feed; (2) Probiotic application: Apply 15-30 ppm of heat-inactivated Lactobacillus plantarum L-137; (3) Parasite control: Regularly monitor for parasites, and treat with freshwater baths when infection is severe; (4) Environmental management: When the water temperature is >28℃, strengthen monitoring and appropriately reduce the stocking density; (5) Dead fish should be removed promptly to prevent the spread of disease.

9. The method for large-scale cage culture of five yellowtail amberjacks according to claim 1, characterized in that, In step (6), feeding should be stopped 48 to 72 hours before harvest; the optimal harvest period is from October to March of the following year.

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