Five methods for artificial breeding of cobia

Abstract

The application provides a method for artificial breeding of fivebarred grouper, which comprises the following steps: artificial induction of spawning, fertilized egg collection and hatching, larva cultivation, juvenile fish cultivation, young fish cultivation and disease prevention and control. High-quality young fish are finally cultivated by hormone induction of artificial induction of spawning, green water cultivation method, taurine reinforced rotifer as the first feed for the larvae, adaptive feeding of brine shrimp and air filling management of the swim bladder. The method provided by the application breaks the dependence on natural juvenile fish in the process of fivebarred grouper breeding, realizes stable, efficient and year-round production of fivebarred grouper seedlings, and provides technical support for the sustainable development of the fivebarred grouper breeding industry.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology, and relates to the cultivation of five-striped yellowtail (Seriola quinqueradiata), specifically to a method for artificial breeding of five-striped yellowtail. Background Technology

[0002] The five-striped yellowtail (Seriola quinqueradiata) is an important economic fish belonging to the order Perciformes, family Carangidae, and genus Seriola, widely distributed in the Northwest Pacific Ocean. This species is characterized by its rapid growth, sweet flesh, and rich fat content, making it highly valuable both nutritionally and economically, and holding an important position in the global aquaculture market. The five-striped yellowtail is rich in vitamin D, which is closely related to human bone formation, and contains a large amount of vitamin E with antioxidant properties. It also contains significant amounts of EPA (which can lower blood cholesterol and prevent arteriosclerosis / stroke / heart disease / high blood pressure) and DHA, which activates brain function, making it an important ingredient for sashimi (raw fish).

[0003] The five-striped yellowtail is a temperate migratory fish with a suitable temperature range of 18–28℃, and the optimal culture temperature is 20–27℃. This species exhibits a pronounced schooling behavior and in its natural environment primarily preys on sardines, saury, horse mackerel, and various cephalopods. Under natural conditions, its spawning period lasts from early spring to summer. The eggs are spherical, buoyant, and 1.1–1.4 mm in diameter. Incubation takes approximately 90 hours at water temperatures of 15–18℃.

[0004] For a long time, amberjack aquaculture has mainly relied on catching natural fish fry from the ocean for cage culture. The collection of natural juveniles is the foundation of the aquaculture industry. Natural juveniles are harvested annually from February to May for artificial cage culture. This production model has the following prominent problems:

[0005] (1) Strong dependence on natural resources: The supply of seedlings depends entirely on the harvesting of wild juvenile fish. It is greatly affected by the natural environment and fluctuations in resource quantity, and the supply is unstable. For example, in 2021, the harvesting of natural juvenile fish in Japan only reached about 40% of the planned amount.

[0006] (2) Significant seasonal limitations: Natural juvenile fish are only available in specific seasons, which limits the aquaculture production cycle and makes it difficult to achieve year-round supply.

[0007] (3) Wild resource pressure: Large-scale harvesting of natural juvenile fish puts pressure on wild populations and does not conform to the concept of sustainable development.

[0008] (4) Difficulty in quality control: The genetic background of natural juvenile fish is unclear, making it difficult to carry out selective breeding and quality control.

[0009] Therefore, there is an urgent need to develop a systematic and efficient artificial breeding technology for five-striped yellowtail to improve the efficiency and quality of seedling production and promote the sustainable development of the five-striped yellowtail aquaculture industry. Summary of the Invention

[0010] This invention addresses the aforementioned problems and aims to provide an artificial breeding technology for Seriola quinqueradiata. Through key processes such as artificial spawning induction, fertilized egg hatching, larval and juvenile rearing, feeding, and disease control, high-quality juvenile fish are ultimately cultivated, achieving efficient, stable, and year-round production of Seriola quinqueradiata seedlings. This solves the problem of traditional aquaculture relying on natural juveniles, enabling stable, efficient, and year-round production of Seriola quinqueradiata seedlings, improving seedling survival rate and quality, and providing technical support for the sustainable development of the Seriola quinqueradiata aquaculture industry.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] The artificial seedling cultivation method for five-striped yellowtail provided by this invention includes the following steps:

[0013] (1) Artificial induction of labor

[0014] Inject oxytocin into the muscles of the pectoral or dorsal fin bases of mature broodstock to induce final maturation, ovulation, and spawning. The injection dose is lower for males than for females.

[0015] The mature broodstock described in this invention are broodstock that have reached grade III gonadal maturity or an egg diameter of 700–800 μm, and are used for artificial spawning induction. They are selected from both naturally matured broodstock and artificially matured broodstock that have undergone nutritional enhancement, photoperiod regulation, and water temperature regulation. Given the unique characteristics of five-yellow yellowtail breeding, artificially matured broodstock are preferred.

[0016] Hormones are used to induce spawning in parent fish that have reached maturity, leading to final maturation, ovulation, and spawning. Spawning is induced by injecting oxytocin (HCG, LRH-A, or GnRHa) into the muscles at the base of the pectoral or dorsal fins. The dosage for male fish is half that for female fish.

[0017] In a preferred embodiment of the present invention, the oxytocin is selected from human chorionic gonadotropin (HCG) or luteinizing hormone-releasing hormone analogs LRH-A or GnRHa.

[0018] Further optimization involves the following HCG injection dosages: 500–600 IU / kg body weight for female fish and 250–300 IU / kg body weight or no injection for male fish; and 20–50 μg / kg body weight for female fish and half the dosage for male fish.

[0019] More preferably, when inducing spawning with HCG, a single injection or a two-injection method should be used. The first injection should contain 30% of the total dose, and the remaining 70% should be injected 8–12 hours later. When inducing spawning with LRH-A, the effect is better when female fish are injected with dioxin at a dose of 2–5 mg / kg body weight.

[0020] In a preferred embodiment of the present invention, fertilization is performed using a method of natural mating assisted artificial insemination to generate fertilized eggs. Specifically:

[0021] Natural mating and spawning: After induced spawning, male and female parent fish are placed in the spawning pond in a specific ratio. Under the stimulation of a slight water flow, they naturally chase each other, mate, and spawn. The spawning pond is equipped with an overflow egg collection device to automatically collect floating fertilized eggs.

[0022] Artificial egg collection and insemination: For individuals that do not spawn naturally, dry artificial insemination can be used. Gently press the female's abdomen to squeeze out the eggs into a dry container, add male semen and stir gently. After 2-3 minutes, add seawater to activate the eggs, let them stand for 5-10 minutes for fertilization, and then transfer them to the incubation system.

[0023] (2) Collection and hatching of fertilized eggs

[0024] After collecting fertilized eggs, they are disinfected and rinsed with clean water, then transferred to incubation equipment, and inferior fertilized eggs are removed. Under conditions of water temperature of 18-20℃, salinity of 30-33‰, dissolved oxygen ≥6 mg / L, and weak light or darkness, incubation is carried out using micro-flow water or still water micro-aeration incubation methods. The incubation density in still water is 500-1000 eggs / L, while the incubation density in flowing water is increased to 1500-2000 eggs / L. Hatching occurs in about 60-90 hours.

[0025] Preferably, the five yellowtail eggs are buoyant eggs, which float on the water surface after fertilization. When collecting fertilized eggs, the fertilized eggs floating on the water surface are collected through the overflow outlet in conjunction with the hatching net box or egg collection net. After collection, they are disinfected by soaking in 5-10 ppm povidone-iodine solution for 3-5 minutes, rinsed with clean water, and then transferred to the hatching equipment.

[0026] The method for removing inferior fertilized eggs is as follows: High-quality fertilized eggs are transparent spherical, with a diameter of 1.2–1.4 mm, a single, centrally located oil globule, and normal embryonic development; inferior eggs are cloudy, have wrinkled membranes, or show abnormal embryonic development and should be removed promptly. The floating egg rate (the percentage of floating eggs out of the total number of eggs) is an important indicator for evaluating the quality of an egg batch.

[0027] (3) Fry rearing of 0-12 day old fish

[0028] For 1-2 days before hatching, the fry are raised in green water. Starting at 3 days old, they are fed rotifers fortified with high unsaturated fatty acids and taurine. During the rearing process, the water temperature is maintained at 21-24℃, the salinity at 32-35‰, and the dissolved oxygen at >5 mg / L. The light intensity is 1000-15000 lux, and the photoperiod is 14L:10D. The daily water exchange rate is 10-30%. Swim bladder aeration is carried out 5-10 days after hatching.

[0029] Preferably, the fry are placed in a volume of 10-50m³. 3 They are raised in circular fiberglass or cement tanks, equipped with a micro-aeration system, a temperature control system, and a lighting system; the stocking density of newly hatched fry is 20-50 fish / L.

[0030] Preferably, during green water cultivation, microalgae (preferably Chlorella sp. or Isochrysis galbana) are added to the cultivation tank, and the algal density is maintained at 500,000 to 1,000,000 cells / mL to create a green water environment. Simultaneously, a light intensity of 1000 to 15000 lux is maintained, preferably a high light intensity of 10000 to 15000 lux for cultivation.

[0031] Preferably, when feeding rotifers at 3 days old, the density of rotifers should be maintained at 10-30 rotifers / mL. The rotifers should be nutritionally fortified for 18-24 hours in advance with a fortifier containing high levels of unsaturated fatty acids DHA and EPA. During the fortification process, 200-800 mg / L of taurine should be added to make the taurine content in the rotifers reach 2.5-7.0 mg / g dry weight.

[0032] Preferred methods for swim bladder aeration management are as follows: the critical period for swim bladder aeration is 5 to 10 days after hatching; keep the water surface clean and free of oil film, maintain appropriate light and water flow (maintain light intensity > 5000 lux and water flow 0.5 to 1.0 cm / s) to promote the fry to rise and inhale air; the swim bladder aeration rate should be greater than 70%.

[0033] The low survival rate of fry was effectively improved by using rotifers for taurine enhancement, high-intensity green water cultivation, and adaptive brine shrimp feeding.

[0034] (4) Frying of fish aged 12 to 45 days

[0035] From 12 to 15 days old, feed the nauplii of Artemia fortified with high unsaturated fatty acids (DHA, EPA). After feeding Artemia and rotifers together for 3 to 5 days, gradually reduce the amount of rotifers. From 25 to 35 days old, feed the nauplii with microparticle compound feed. After feeding Artemia and rotifers together for 5 to 7 days, gradually transition to a fully artificial compound feed. At the same time, grade and screen the nauplii as appropriate during the breeding process.

[0036] Preferably, an adaptive feeding method is used for transitional feeding of brine shrimp, with the brine shrimp density maintained at 0.5-2 shrimp / mL. The feeding time of brine shrimp is adjusted according to the changes in the body density of the fry. Feeding of brine shrimp is stopped 3-4 hours before dusk to ensure that the fry maintain neutral buoyancy at night. Especially during the critical period of 13-17 days of age, afternoon feeding is reduced to reduce the mortality of fry sinking.

[0037] During the transition period of compound feed, feed micro-particle compound feed with a particle size of 200-500μm and feed it together with Artemia for 5-7 days, and then gradually transition to a completely artificial compound feed.

[0038] During the breeding process, as the fry grow, the breeding density is gradually reduced to 5-10 fish / L, and grading and screening are carried out in a timely manner.

[0039] (5) Frying and harvesting of 45-90 day old fish

[0040] The juvenile fish are then transferred to indoor rearing ponds or outdoor net cages for cultivation, with the rearing density controlled at 1–3 kg / m². 3 Feed them with extruded compound feed specifically for juvenile fish, with the particle size gradually increasing as the fish grows (0.5~2mm). The daily feeding rate is 3~8% of their body weight, divided into 4~6 feedings. Cultivate them under conditions of water temperature 20~25℃, salinity 30~35‰, and dissolved oxygen >5 mg / L. When the fish reach a body length of 5~8 cm and a weight of 5~15 g, they can be sold from the pond or transferred to the growth stage.

[0041] (6) Disease prevention and control management:

[0042] (a) The seedling water is sterile to ensure that the seedling water is free of pathogenic microorganisms;

[0043] (b) Biosafety management: Strictly control the entry and exit of personnel and materials into the seedling workshop; disinfect tools and equipment regularly; cultivate live bait separately to avoid cross-contamination;

[0044] (c) Prevention and control of common diseases: Pay attention to the prevention and control of common bacterial diseases. In the early stage of the disease, use 0.5-1.0 ppm ozone water immersion for disinfection or feed probiotics to enhance immunity;

[0045] (d) Parasite control: Treat with a freshwater bath for 5-10 minutes or a 100-150 ppm hydrogen peroxide bath for 25-35 minutes to expel parasites;

[0046] (e) Health monitoring: Conduct pathogen detection regularly and isolate and treat any abnormalities promptly.

[0047] After the above-mentioned cultivation method, the fish fry reached an average body length of 6 cm and a weight of 8 g at 90 days old, which is the standard size for harvesting.

[0048] Compared with the prior art, the beneficial effects of this application are as follows:

[0049] (1) Get rid of dependence on natural resources: The artificial breeding method of the present invention obtains seedlings, which overcomes the defects of relying on wild juvenile fish harvesting and realizes the stabilization and sustainability of seedling supply;

[0050] (2) Achieve year-round production: By using photoperiod and temperature control technology to mature broodstock in the off-season, early egg collection can be carried out from December to February; by combining the natural rhythm to cultivate broodstock, egg collection can be carried out during the normal spawning season from April to June, and egg collection can be carried out for 6 months of the year, thus achieving egg collection and seedling cultivation at any time of the year, breaking the seasonal restrictions.

[0051] (3) Improve seedling quality: By optimizing nutrition fortification and cultivation management, the survival rate and quality of seedlings can be significantly improved, and the deformity rate can be reduced;

[0052] (4) Facilitates genetic improvement: Artificial breeding helps in the selection and genetic improvement of parents, and cultivates varieties with excellent traits such as high growth and disease resistance;

[0053] (5) Reduce production costs: Large-scale production can reduce seedling costs and improve the economic benefits of breeding;

[0054] (6) Environmentally friendly: It reduces the pressure of fishing on wild resources and meets the requirements of green development of aquaculture. Detailed Implementation

[0055] 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.

[0056] 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.

[0057] 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.

[0058] This invention addresses the technical problems of the current reliance on wild-caught amberjack for seedling supply, which leads to strong dependence on natural resources, significant seasonal limitations, high pressure on wild resources, and difficulties in quality control. It develops a method for cultivating five-lined yellowtail amberjack juveniles, with the specific measures as follows:

[0059] 1. Artificial induction of labor

[0060] Chopped fish that have undergone nutritional enhancement, photoperiod regulation, and water temperature regulation, and whose gonadal maturity reaches level III or whose egg diameter reaches 700-800 μm, are selected for artificial spawning induction.

[0061] Hormone induction is used to induce spawning in broodstock that have reached maturity, resulting in final maturation, ovulation, and spawning.

[0062] (1) Selection of oxytocin: Human chorionic gonadotropin (HCG) is preferred, and luteinizing hormone-releasing hormone analogs (LRH-A or GnRHa) can also be used.

[0063] (2) HCG-induced labor protocol:

[0064] ① Single injection method: female fish are injected with 500-600 IU / kg body weight, and male fish are injected with 250-300 IU / kg body weight or no injection is required;

[0065] ② Two-injection method: The first injection is 30% of the total dose, and the remaining 70% is injected 8-12 hours later;

[0066] ③ Injection site: Intramuscular injection at the base of the pectoral fin or the base of the dorsal fin. Gently massage the injection site after injection to promote absorption.

[0067] (3) LRH-A spawning induction program: The injection dose for female fish is 20-50 μg / kg body weight. The effect is better when combined with 2-5 mg / kg body weight of domperidone (DOM). The dose for male fish is halved.

[0068] (4) Effect time: Under water temperature of 18-20℃, the effect time after HCG injection is 36-54 hours, and spawning usually occurs from dusk to night.

[0069] (5) Natural mating and spawning: After induced spawning, male and female parent fish are placed in the spawning pond in proportion. Under the stimulation of a slight water flow, they naturally chase each other, mate, and spawn. The spawning pond is equipped with an overflow egg collection device to automatically collect floating fertilized eggs.

[0070] (6) Artificial egg collection and insemination: For individuals that do not lay eggs naturally, dry artificial insemination can be used. Gently press the abdomen of the female fish to squeeze out the eggs into a dry container, add the male fish semen and stir gently. After 2-3 minutes, add seawater to activate the eggs. Let the eggs stand for 5-10 minutes before transferring them to the incubation system.

[0071] 2. Collection and hatching of fertilized eggs

[0072] (1) Collection of fertilized eggs: The eggs of the five yellowtail are buoyant and float on the water surface after fertilization. The fertilized eggs are collected through the overflow outlet in conjunction with the hatching net box or egg collection net. After collection, they are disinfected by soaking in 5-10 ppm povidone-iodine solution for 3-5 minutes, rinsed with clean water, and then transferred to the hatching equipment.

[0073] (2) Oocyte quality assessment: High-quality fertilized eggs are transparent spherical with a diameter of 1.2-1.4 mm, with a single, centrally located oil globule, and normal embryonic development; low-quality eggs are cloudy, have wrinkled membranes, or show abnormal embryonic development and should be removed promptly. The floating egg rate (the percentage of floating eggs out of the total number of eggs) is an important indicator for evaluating the quality of an egg batch.

[0074] (3) Hatching conditions: The hatching water temperature should be controlled at 18-20℃, salinity at 30-33‰, dissolved oxygen at ≥6 mg / L, and low light or darkness. Micro-flow or still water micro-aeration hatching method should be adopted. Under the above conditions, the fertilized eggs will hatch after about 60-90 hours.

[0075] (4) Hatching density: The hatching density in still water is 500-1000 grains / liter, while the hatching density in flowing water can be appropriately increased to 1500-2000 grains / liter.

[0076] 3. Fry rearing (0-12 days old)

[0077] (1) Cultivation facilities: using facilities with a volume of 10-50m³ 3 Circular fiberglass or cement tanks, equipped with micro-aeration systems, temperature control systems, and lighting systems.

[0078] (2) Initial rearing density: The stocking density of newly hatched fry is 20-50 fish / L.

[0079] (3) Green water cultivation method: Add microalgae (Chlorella sp. or Isochrysis galbana) to the cultivation pond 1-2 days before the fry start feeding, maintain the algae density at 500,000 to 1,000,000 cells / mL, and use a light intensity of 1,000 to 15,000 lux, preferably 10,000 to 15,000 lux, to form a green water environment; green water can improve water quality, enhance the visual contrast of fry, and promote feeding.

[0080] (4) Feeding the first food: The fry start feeding 3 days after hatching (3 dph). First feed them with nutritionally fortified rotifers (Brachionus plicatilis); the density of rotifers should be maintained at 10-30 rotifers / mL; the rotifers need to be nutritionally fortified with a fortifier containing high unsaturated fatty acids (DHA, EPA) for 18-24 hours in advance.

[0081] (5) Taurine fortification: Taurine 200-800 mg / L is added during the rotifer fortification process to make the taurine content in the rotifer reach 2.5-7.0 mg / g dry weight, which meets the special nutritional requirements of fry for taurine.

[0082] (6) Environmental control: water temperature is maintained at 21-24℃, salinity is 32-35‰, dissolved oxygen is >5 mg / L; light intensity is 1000-15000 lux, photoperiod is 14L:10D; daily water exchange is 10-30%.

[0083] (7) Swim bladder aeration management: The critical period for swim bladder aeration is 5 to 10 days after hatching; use surface skimming devices or air stones for micro-aeration to remove the oil film on the water surface, keep the water surface clean and free of oil film, maintain appropriate light intensity (>5000 lux) and appropriate water flow (0.5 to 1.0 cm / s) to promote the fry to float to the surface and swallow air; the swim bladder aeration rate should be greater than 70%.

[0084] 4. Fry rearing (12-45 days old)

[0085] (1) Transitional feeding of Artemia: Start feeding Artemia nauplii with nutritional fortification from 12 to 15 days old; Artemia needs to be fortified with DHA and EPA; maintain the density of Artemia at 0.5 to 2 nauplii / mL; after feeding Artemia and rotifers together for 3 to 5 days, gradually reduce the amount of rotifers.

[0086] (2) Feeding strategy optimization: Adaptive feeding method is adopted, and the feeding time and amount of brine shrimp are adjusted according to the changes in the body density of fry to avoid overfeeding, which would cause the fry to sink and die due to increased body density. Feeding brine shrimp should be stopped before dusk to ensure that the fry maintain neutral buoyancy at night. It is preferable to stop feeding brine shrimp 3 to 4 hours before dusk during the period of 13 to 17 days of age to ensure that the fry maintain neutral buoyancy at night.

[0087] (3) Transition to compound feed: Start feeding micro-particle compound feed (particle size 200-500 μm) from 25 to 35 days old, and gradually transition to fully artificial compound feed after feeding with Artemia for 5 to 7 days.

[0088] (4) Controlling the stocking density: As the fry grow, gradually reduce the stocking density to 5-10 fish / L; conduct timely grading and screening to reduce individual differences and cannibalism.

[0089] 5. Juvenile fish rearing and harvesting (45-90 days old)

[0090] (1) Cultivation facilities: Transfer to indoor breeding ponds or outdoor net cages with a volume of 50-200 m³ for cultivation.

[0091] (2) Feeding: Feed the fish with extruded compound feed for juvenile fish. The particle size should be gradually increased as the fish size increases (0.5-2.0 mm). The daily feeding rate is 3-8% of the body weight, and the fish should be fed 4-6 times.

[0092] (3) Cultivation density: controlled at 1-3 kg / m³.

[0093] (4) Environmental conditions: water temperature 20-25 ℃, salinity 30-35‰, dissolved oxygen >5 mg / L;

[0094] (5) Specifications for leaving the pond: When the body length is 5-8 cm and the weight is 5-15 g, it can be sold or transferred to the growth stage.

[0095] 6. Disease prevention and control

[0096] (1) Seedling water treatment: A multi-stage water treatment system with sand filtration, ultraviolet disinfection and ozone treatment is adopted to ensure that the water used for seedling cultivation is free of pathogenic microorganisms.

[0097] (2) Biosafety management: Strictly control the entry and exit of personnel and materials in the seedling workshop; disinfect tools and equipment regularly; cultivate live bait (rotifers, brine shrimp) separately to avoid cross-contamination.

[0098] (3) Prevention and control of common diseases: Pay attention to the prevention and control of bacterial diseases such as vibriosis and epitheliocystis; in the early stage of the disease, ozone water bath with 0.5 to 1.0 ppm can be used for disinfection or probiotics can be fed to enhance immunity.

[0099] (4) Parasite control: Pay attention to the prevention and control of monogenean trematode infection (Benedenia seriolae); treat with deworming by fresh water bath (5-10 minutes) or hydrogen peroxide bath (100-150 ppm, 30 minutes);

[0100] (5) Health monitoring: Conduct pathogen detection regularly and isolate and treat any abnormalities in a timely manner.

[0101] The present invention will be further described in detail below with reference to specific embodiments.

[0102] Example 1: Standard Seedling Raising Process

[0103] 1. Artificial Spawning Induction: Five female yellowtail broodstock (10 with abdominal swelling reaching grade III and egg diameter exceeding 700 mm) and 15 mature males were selected for spawning induction. A single HCG injection was used, with females injected at 600 IU / kg and males at 300 IU / kg. Spawning successfully occurred 48 hours after induction at a water temperature of 19℃, with peak spawning occurring between 2:00 AM and 6:00 AM.

[0104] 2. Collection of fertilized eggs: Floating fertilized eggs are collected on the water surface using a 300-mesh egg collection net, with a daily collection volume of 3.2 million eggs.

[0105] 3. Fertilized egg treatment: Collected fertilized eggs were disinfected with 100 ppm povidone-iodine solution for 1 minute, rinsed, and then transferred to an incubation tank. The incubation water temperature was 21℃, the salinity was 33‰, and the incubation density was 800 eggs / L. Hatching occurred 48 hours after fertilization, with a hatching rate of 85%.

[0106] 4. Larval rearing: Newly hatched larvae are transferred to a 30m... 3 The rearing pond had a density of 30 rotifers / L; Chlorella was added to create green water (density of 800,000 cells / mL); starting from 3 days old, rotifers fortified with taurine (400 mg / L) and DHA were fed at a density of 20 rotifers / mL; during the rearing process, the water temperature was 22℃, the light intensity was 10,000 lux, and the photoperiod was 14L:10D.

[0107] 5. Fry rearing: Begin feeding enhanced brine shrimp at a density of 1 shrimp / mL from 12 days of age, co-feeding with rotifers until 15 days of age, after which rotifer feeding is discontinued. Adaptive feeding method is used, and brine shrimp feeding is stopped after 4 PM. Microparticle formulated feed (300 μm) is introduced from 25 days of age, and gradually transitioned to a fully formulated feed after 30 days of age.

[0108] 6. Juvenile fish rearing: 45-day-old juvenile fish (approximately 2.5 cm in length) are transferred to a 100 m... 3 The stocking ponds were maintained at a density of 2 fish / L. The juvenile fish were fed extruded compound feed with a particle size of 0.8–1.5 mm and a daily feeding rate of 5%. At 90 days of age, the fish had an average body length of 6 cm and a weight of 8 g, reaching the standard size for slaughter.

[0109] Example 2: Early egg retrieval and year-round production

[0110] Based on the above fry cultivation method, combined with the cultivation of five yellowtail broodstock, year-round production through early egg collection can be achieved. To ensure a year-round supply of fry, two batches of broodstock are established, and year-round egg collection is achieved through staggered peak management.

[0111] Batch A broodstock: These were artificially induced to mature out of season. Starting in June, the photoperiod was adjusted to 15L:9D, and the water temperature was gradually increased from 16℃ to 19℃. Early egg collection was conducted from December to February. The specific methods are as follows:

[0112] (1) Breeding conditions: The broodstock were raised in an indoor recirculating aquaculture pond (200 cubic meters) equipped with a precise temperature control system and an adjustable lighting system. The initial water temperature was 20℃ and the salinity was 33‰.

[0113] (2) Nutritional fortification: Starting in June, a fortified compound feed was used, with 48% crude protein, 15% crude fat, and fish oil (EPA+DHA content 30%) added to achieve an n-3 HUFA of 2.5%. Astaxanthin 40 mg / kg, taurine 0.8%, and vitamin E 300 mg / kg were also added. Fresh squid was supplemented twice a week. The daily feeding amount was 1.5-2% of body weight.

[0114] (3) Photoperiod regulation: Photoperiod regulation will be initiated on July 1. From July 1 to August 15, short-day treatment will be implemented with a light regime of 8L:16D (lighting time 06:00~14:00) and a light intensity of 150 lux. From August 16, long-day treatment will be implemented with a light regime adjusted to 18L:6D (lighting time 04:00~22:00) and a light intensity maintained at 150 lux.

[0115] (4) Water temperature control: Starting from July 1, the water temperature will be gradually adjusted to 21℃ and kept constant, with a temperature adjustment rate of 0.5℃ / day. One week before induced labor, the water temperature will be adjusted to 19℃.

[0116] (5) Maturity check: Starting in early October, check the maturity of the parent fish weekly. When the abdominal swelling of the female fish reaches grade III and the egg diameter reaches 750 mm, it is determined to be mature and can be induced to spawn.

[0117] Batch B parent fish: bred according to natural rhythms, with eggs collected during the normal spawning season from April to June.

[0118] By rotating two batches of broodstock, an egg collection cycle of more than 6 months can be achieved throughout the year, meeting the year-round seedling supply demand.

[0119] Example 3: Optimization of High Survival Rate Cultivation

[0120] To address the low survival rate of fry, the following optimization measures were implemented:

[0121] 1. Taurine fortification in rotifers: 800 mg / L of taurine was added to the fortification solution, so that the taurine content in the rotifers reached 7.0 mg / g dry weight, which is close to the level of wild copepods.

[0122] 2. High-intensity green water cultivation: Using 14850 lux high light intensity combined with green water cultivation significantly improves the feeding rate and survival rate of fry.

[0123] 3. Adaptive brine shrimp feeding: Adjust the feeding strategy in real time according to the fry density, reduce the afternoon feeding amount during the critical period of 13-17 days of age, so that the fry can maintain neutral buoyancy at night and reduce sinking and mortality.

[0124] Through this optimization process, the survival rate of fry increased from 0.1–2.0% to 9.2–11.0%.

[0125] 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 artificially raising seedlings of five-striped yellowtail, characterized in that, Includes the following steps: (1) Artificial induction of labor Inject oxytocin into the muscles of the pectoral or dorsal fin bases of broodstock that have reached maturity to induce final maturity, ovulation and spawning. The injection dose for males is lower than that for females. (2) Collection and hatching of fertilized eggs After collecting fertilized eggs, disinfect and rinse them with clean water, then transfer them to the incubation equipment and remove inferior fertilized eggs. Incubate them in water at 18-20℃, with a salinity of 30-33‰, dissolved oxygen ≥6 mg / L, and under weak light or dark conditions, using a micro-flow or still water micro-aeration method until they hatch. (3) Fry rearing of 0-12 day old fish For 1-2 days before hatching, the fry are raised in green water. Starting at 3 days old, they are fed rotifers fortified with high unsaturated fatty acids and taurine. During the rearing process, the water temperature is maintained at 21-24℃, the salinity at 32-35‰, and the dissolved oxygen at >5 mg / L. The light intensity is 1000-15000 lux, and the photoperiod is 14L:10D. The daily water exchange rate is 10-30%. Swim bladder aeration is implemented 5-10 days after hatching. (4) Frying of fish aged 12 to 45 days Starting at 12-15 days old, feed Artemia nauplii fortified with high unsaturated fatty acids. After feeding Artemia and rotifers together for 3-5 days, gradually reduce the amount of rotifers. Starting at 25-35 days old, feed microparticle compound feed. After feeding Artemia and rotifers together for 5-7 days, gradually transition to a fully artificial compound feed. At the same time, grade and screen the animals as appropriate during the breeding process. (5) Frying and harvesting of 45-90 day old fish The juvenile fish are transferred to indoor culture ponds or outdoor net cages for cultivation. They are fed with extruded compound feed specifically for juvenile fish, with the particle size gradually increasing as the fish grow. They are cultivated under conditions of water temperature of 20-25 ℃, salinity of 30-35‰, and dissolved oxygen >5 mg / L. When the fish reach a body length of 5-8 cm and a weight of 5-15 g, they can be sold or transferred to the growth stage.

2. The method for artificially raising five-striped yellowtail seedlings according to claim 1, characterized in that, It also includes disease prevention and control management: (1) The seedling water is sterile to ensure that the seedling water is free of pathogenic microorganisms; (2) Biosafety management: Strictly control the entry and exit of personnel and materials in the seedling workshop; disinfect tools and equipment regularly; cultivate live bait separately to avoid cross-contamination; (3) Prevention and control of common diseases: Pay attention to the prevention and control of common bacterial diseases. In the early stage of the disease, use 0.5-1.0 ppm ozone water immersion for disinfection or feed probiotics to enhance immunity; (4) Parasite control: Treat with a freshwater bath for 5-10 minutes or a 100-150 ppm hydrogen peroxide bath for 25-35 minutes to expel parasites; (5) Health monitoring: Conduct pathogen detection regularly and isolate and treat any abnormalities in a timely manner.

3. The method for artificially raising seedlings of five-striped amberjack according to claim 1, characterized in that, In step (1), The oxytocin is selected from human chorionic gonadotropin (HCG) or luteinizing hormone-releasing hormone analogs LRH-A or GnRHa. The HCG injection dosage is 500–600 IU / kg body weight for female fish and 250–300 IU / kg body weight for male fish, or no injection; the LRH-A injection dosage is 20–50 μg / kg body weight for female fish and half the dosage for male fish. Fertilized eggs are produced by using natural mating assisted artificial insemination.

4. The method for artificially raising seedlings of five-striped amberjack according to claim 3, characterized in that, When inducing labor with HCG, a single injection or a two-injection method can be used. The first injection is 30% of the total dose, and the remaining 70% is injected 8-12 hours later. When using LRH-A to induce spawning, it is more effective to administer it to female fish by injecting them with dioxin at a dose of 2-5 mg / kg body weight.

5. The method for artificially raising seedlings of five-striped amberjack according to claim 1, characterized in that, In step (2), When collecting fertilized eggs, use an overflow outlet in conjunction with an incubation net box or egg collection net to collect the fertilized eggs floating on the water surface. After collection, disinfect them by soaking in a 5-10 ppm povidone-iodine solution for 3-5 minutes, rinse with clean water, and then transfer them to the incubation equipment. When fertilized eggs are hatched, the hatching density in still water is 500-1000 eggs / liter, while the hatching density in flowing water is increased to 1500-2000 eggs / liter.

6. The method for artificially raising seedlings of five-striped amberjack according to claim 1, characterized in that, In step (3), the fry are raised in a circular fiberglass or cement tank with a volume of 10-50 m³, equipped with a micro-aeration system, a temperature control system and a lighting system; the stocking density of newly hatched fry is 20-50 fish / L. During green water cultivation, microalgae are added to the cultivation tank, and the algae density is maintained at 500,000 to 1,000,000 cells / mL, with a light intensity of 1,000 to 15,000 lux. When feeding rotifers at 3 days old, the density of rotifers should be maintained at 10-30 rotifers / mL. The rotifers should be nutritionally fortified 18-24 hours in advance with a fortifier containing high levels of unsaturated fatty acids DHA and EPA. During the rotifer enhancement process, taurine of 200–800 mg / L was added to bring the taurine content in the rotifers to 2.5–7.0 mg / g dry weight. The following are the methods for swim bladder aeration management: The critical period for swim bladder aeration is 5 to 10 days after hatching; keep the water surface clean and free of oil film, maintain appropriate light and water flow to promote the fry to rise and inhale air; the swim bladder aeration rate should be greater than 70%.

7. The method for artificially raising seedlings of five-striped amberjack according to claim 6, characterized in that, When managing swim bladder inflation, maintain a light intensity >5000 lux and a water flow of 0.5–1.0 cm / s.

8. The method for artificially raising seedlings of five-striped amberjack according to claim 1, characterized in that, In step (4), an adaptive feeding method is used to transition the feeding of brine shrimp. The brine shrimp density is maintained at 0.5 to 2 shrimp / mL. The feeding time of brine shrimp is adjusted according to the change in the body density of the fry. The feeding of brine shrimp is stopped 3 to 4 hours before dusk to ensure that the fry maintain neutral buoyancy at night. During the transition period of compound feed, feed micro-particle compound feed with a particle size of 200-500μm and feed it together with Artemia for 5-7 days, and then gradually transition to a completely artificial compound feed. During the breeding process, as the fry grow, the breeding density is gradually reduced to 5-10 fish / L, and grading and screening are carried out in a timely manner.

9. The method for artificially raising seedlings of five-striped amberjack according to claim 1, characterized in that, In step (5), the rearing density of juvenile fish is controlled at 1–3 kg / m². 3 The daily feeding rate of extruded compound feed for juvenile fish is 3-8% of their body weight, divided into 4-6 feedings.

10. A species of five yellowtail fry, characterized in that, The seedlings were cultivated using the seedling cultivation method described in any one of claims 1 to 9.