Artificial breeding method of wild Naozhou large yellow croaker

Abstract

This invention provides a method for the artificial breeding of wild *Large Yellow Croaker* (also known as Naozhou croaker), belonging to the field of aquatic animal breeding technology. The method includes the following steps: wild *Large Yellow Croaker* are domesticated and then subjected to intensive cultivation until their gonads mature. The resulting broodstock are then artificially induced to spawn and naturally fertilized to obtain fertilized eggs. These fertilized eggs are then hatched and cultured to obtain *Large Yellow Croaker* fry. The artificial spawning induction method includes injecting hormones into the broodstock in two steps. This invention creates favorable conditions for the large-scale farming of *Large Yellow Croaker*, and can produce a large population of artificially bred *Large Yellow Croaker* fry.

Description

Technical Field

[0001] This invention belongs to the field of aquatic animal breeding technology, specifically relating to an artificial breeding method for wild large yellow croaker. Background Technology

[0002] According to population ecology, large yellow croaker in my country is generally divided into three groups: the Min-Yue East large yellow croaker represented by Ningde, Fujian; the Daiqu large yellow croaker from Zhoushan, Zhejiang; and the Naozhou large yellow croaker mainly from the nearshore waters of Naozhou, Guangdong. Among them, the Min-Yue East and Daiqu groups of large yellow croaker have been developed and studied, and industrial scale has been formed in Fujian, Zhejiang and other places. However, the Naozhou large yellow croaker has not yet been developed and utilized.

[0003] The large yellow croaker (Croton hainanense) possesses unique advantages in adapting to the high sea conditions of deep-sea aquaculture. This characteristic makes it a more advantageous species for developing deep-sea aquaculture in Guangdong. Large-scale aquaculture will effectively solve the bottleneck of the industry's development, which is hindered by the poor heat tolerance of the large yellow croaker from Fujian (Min-Yue East) and Zhejiang (Dai-Qu) in the South China Sea. It is expected to become an important species for future deep-sea aquaculture in the South China Sea. Currently, existing artificial breeding methods for large yellow croaker suffer from significant stress during wild capture and domestication, resulting in short survival times and poor reproductive performance of broodstock under artificial conditions. Furthermore, artificial egg collection and artificial insemination suffer from low hatching rates and low fry survival rates, making it difficult to obtain large populations of fry through artificial breeding, thus restricting the progress of deep-sea aquaculture of large yellow croaker. Summary of the Invention

[0004] In view of this, the present invention provides an artificial breeding method for wild Naozhou large yellow croaker. Through domestication, intensive cultivation, artificial spawning induction and seedling cultivation of wild Naozhou large yellow croaker parent fish, a large number of artificially bred Naozhou large yellow croaker fry populations can be obtained.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for the artificial breeding of wild large yellow croaker (Cyprinus naanensis), comprising the following steps:

[0007] Wild Naozhou yellow croaker is domesticated and then intensively cultivated until its gonads mature. The resulting parent fish are then artificially induced to spawn and naturally fertilized to obtain fertilized eggs. These fertilized eggs are then hatched and raised to produce Naozhou yellow croaker fry.

[0008] The artificial spawning method involves injecting hormones into the parent fish of the large yellow croaker in two steps. The first step involves injecting hormones including luteinizing hormone-releasing hormone A2 and human chorionic gonadotropin, while the second step involves injecting hormones including luteinizing hormone-releasing hormone A3.

[0009] Preferably, the acclimatization environmental conditions are: water temperature 21.5~22.5℃, pH value 8.0~8.3, dissolved oxygen above 5.0mg / L, ammonia nitrogen below 0.01mg / L, and light intensity 1000~1500 lux;

[0010] The acclimatization includes temporary rearing and acclimatization cultivation; the temporary rearing period is 5-7 days; the salinity of the water used for temporary rearing is 18-22;

[0011] The domestication and cultivation period is 20-26 days; the salinity of the water used for domestication and cultivation is 28-33; fresh marine fish are fed twice a day during the domestication and cultivation period; the daily feeding amount of fresh marine fish is 3%-5% of the body weight of wild Naozhou large yellow croaker.

[0012] Preferably, the environmental conditions for enhanced cultivation are as follows: water temperature gradually increases from 21.5~22.5℃ to 24.5~25.5℃ at a rate of 0.5℃ per day; water salinity is 28~33; pH value is 8.0~8.3; dissolved oxygen is above 5.0mg / L; ammonia nitrogen is below 0.01mg / L; light intensity is 500~800 lux; and water flow rate is 50~80L / min.

[0013] Preferably, during the enhanced breeding period, the feed is provided twice daily;

[0014] The fortified feed includes live sandworms, fresh oyster meat, vitamin C, and vitamin E; the vitamin C accounts for 0.2% to 0.5% of the fortified feed by mass, and the vitamin E accounts for 0.1% to 0.2% of the fortified feed by mass; the daily feeding amount of the fortified feed is based on satiated feeding.

[0015] Preferably, when the parent fish of the large yellow croaker from Naozhou is female, the volume of hormone injected in the first step or the second step is 0.9~1.1mL / kg.

[0016] When the parent fish of the large yellow croaker from Naozhou are male, the volume of hormone injected in the first step or the second step is 0.45~0.55mL / kg.

[0017] The working concentration of luteinizing hormone-releasing hormone A2 and the working concentration of human chorionic gonadotropin (hCG) injected in the first step are 10 μg / ml and 1000 IU / mL, respectively.

[0018] The working concentration of luteinizing hormone-releasing hormone A3 in the second injection is 5 μg / ml.

[0019] Preferably, the interval between the first injection and the second injection is 24-26 hours;

[0020] Anesthesia is also included before the first or second injection; the anesthesia time is 2-3 minutes.

[0021] Preferably, the environmental conditions for natural fertilization or hatching are: water temperature 24.5~25.5℃, water salinity 28~33, pH value 8.0~8.3, dissolved oxygen above 5.0mg / L, ammonia nitrogen below 0.01mg / L, and light intensity 500~800lux.

[0022] Preferably, the environmental conditions for seedling cultivation are: water temperature 24.5~25.5℃;

[0023] The seedling cultivation includes a larvae cultivation stage and a fry cultivation stage; the water in the larvae cultivation stage contains Chlorella; the water in the fry cultivation stage contains Chlorella, photosynthetic bacteria and Bacillus thuringiensis.

[0024] Preferably, the seedlings cultivated include 4-7 day old fry, 8-20 day old fry, 21-35 day old fry, and 36-40 day old fry.

[0025] Feed for 4-7 day old fry includes Brachiopoda rotifers;

[0026] Fish fry aged 8-20 days should be fed diets including copepod nauplius larvae;

[0027] Fish fry aged 21-35 days should be fed with Artemia nauplii;

[0028] The feed for 36-40 day old fish fry includes Artemia nauplii and formulated feed for juvenile and young large yellow croaker.

[0029] Preferably, the initial density of the 4-7 day old larvae is 0.7 million larvae / m³. 3 .

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] This invention provides a method for the artificial breeding of wild large yellow croaker (Cyprinus naanensis), comprising the following steps:

[0032] Wild *Large Yellow Croaker* from Naozhou Island are domesticated and then intensively cultured until their gonads mature. The resulting broodstock are then artificially induced to spawn and naturally fertilized to obtain fertilized eggs. These fertilized eggs are then hatched and raised to produce *Large Yellow Croaker* fry. The preferred method for artificially inducing spawning involves injecting hormones into the broodstock in two steps. The first step involves injecting hormones including luteinizing hormone-releasing hormone A2 and human chorionic gonadotropin (hCG), and the second step involves injecting hormones including luteinizing hormone-releasing hormone A3. This invention, based on the living habits, feeding, and activity characteristics of wild *Large Yellow Croaker*, regulates the methods of domestication, intensive cultivation, artificial spawning induction, and fry cultivation, effectively improving the survival rate and reproductive performance of artificially bred *Large Yellow Croaker*, and increasing the survival rate of fry. This invention employs the described method for the artificial breeding of wild *Large Yellow Croaker* cultivars. After domestication, the survival rate of the wild *Large Yellow Croaker* cultivars exceeded 80%. A total of 426.6g of fertilized eggs were collected after artificial spawning and natural fertilization, with a total egg count of approximately 455,000 and a fertilized egg count of approximately 264,000, resulting in a fertilization rate of 58%. After hatching, the initial hatching number of fry was approximately 169,000, with a hatching rate of 64%. At 40 days of age, the number of fry was approximately 98,000, with a survival rate of 57.9%. It is evident that the method of this invention achieves high fertilization and hatching rates, and can yield a large artificially bred population of *Large Yellow Croaker* fry. This invention provides an effective method for the large-scale farming of *Large Yellow Croaker* cultivars. Detailed Implementation

[0033] This invention provides a method for the artificial breeding of wild large yellow croaker (Cyprinus naanensis), comprising the following steps:

[0034] Wild Naozhou yellow croaker is domesticated and then intensively cultivated until its gonads mature. The resulting parent fish are then artificially induced to spawn and naturally fertilized to obtain fertilized eggs. These fertilized eggs are then hatched and raised to produce Naozhou yellow croaker fry. The artificial spawning method involves injecting hormones into the parent fish in two steps. The first step involves injecting hormones including luteinizing hormone-releasing hormone A2 and human chorionic gonadotropin (hCG), and the second step involves injecting hormones including luteinizing hormone-releasing hormone A3.

[0035] In this invention, the wild *Large Yellow Croaker* (a type of culter fish) is preferably captured by purse seine netting along its migration route. The mesh size of the purse seine net is preferably greater than 5 cm, more preferably 5-10 cm, and most preferably 6 cm. The capture time preferably includes the culter fish's breeding season. The capture method of this invention results in a high survival rate of wild *Large Yellow Croaker* and good reproductive performance after enhanced culture. After capture, the wild *Large Yellow Croaker* are transported back to the harbor in a live-water tank, and then transferred to indoor culture ponds for acclimatization. The environmental conditions for transportation are: water temperature 21.5-22.5℃, dissolved oxygen above 6 mg / L; or water temperature can be 21℃ or 22℃, dissolved oxygen can be 7 mg / L. The transport water is preferably treated with anesthetics and anti-stress agents. The anesthetic preferably includes clove oil (containing 10% eugenol), and the working concentration of the anesthetic is preferably 5 mg / L. The anti-stress agent preferably includes γ-aminobutyric acid (GABA), and the working concentration of the anti-stress agent is preferably 0.05 mg / L. The transportation time is preferably within 1 hour. Using the above transportation conditions, the present invention can reduce stress response and improve survival rate and reproductive performance.

[0036] In this invention, the preferred environmental conditions for acclimatization are: water temperature 21.5~22.5℃, pH 8.0~8.3, dissolved oxygen above 5.0 mg / L, ammonia nitrogen below 0.01 mg / L, and light intensity 1000~1500 lux; the water temperature can be 22℃, and the dissolved oxygen can be 7 mg / L. The light intensity can be 1100 lux, 1200 lux, 1300 lux, or 1400 lux. The acclimatization preferably includes temporary rearing and acclimatization cultivation; the temporary rearing time is preferably 5~7 days, and can be 6 days; the salinity of the water used for temporary rearing is preferably 18~22, and can be 19, 20, or 21; the water used for temporary rearing preferably contains an anti-stress agent and an antibacterial agent. The anti-stress agent preferably includes esterified vitamin C, and the concentration of the esterified vitamin C is preferably 4~6 mg / m³. 3 Water body. The antibacterial agent preferably includes enrofloxacin powder. The dosage of the enrofloxacin powder is 10-15 mg / m³. 3Water body. This invention alleviates environmental stress by adding anti-stress agents and antibacterial agents to the water body, avoiding short survival time of wild fry due to excessive stress, preventing infection of broodstock, and improving the survival rate and reproductive performance of broodstock. No feed is provided during the temporary rearing period. After 7 days of temporary rearing, acclimatization and cultivation are carried out. The preferred acclimatization and cultivation period is 20-26 days, specifically 21, 22, 23, 24, or 25 days; the preferred salinity of the water body for acclimatization and cultivation is 28-33, specifically 29, 30, 31, or 32. Fresh marine fish are fed twice daily during the acclimatization and cultivation period; the preferred fresh marine fish are mackerel, blue trevally, or squid. As one feasible method, the fish meat is cleaned, the back muscle is removed, disinfected with iodine, and cut into pieces before feeding. The daily feeding amount of fresh marine fish is 3%-5% of the body weight of wild large yellow croaker, preferably 4%. This invention cuts the fish meat into chunks, making it convenient to feed and less likely to pollute the water.

[0037] After domestication, intensive cultivation is carried out. In this invention, the preferred environmental conditions for intensive cultivation are: water temperature gradually increased from 21.5~22.5℃ to 24.5~25.5℃ at a rate of 0.5℃ per day; water salinity 28~33; pH value 8.0~8.3; dissolved oxygen above 5.0 mg / L; ammonia nitrogen below 0.01 mg / L; light intensity 500~800 lux; natural photoperiod 12L:12D; and water flow rate 50~80 L / min. Alternatively, the water temperature can be 25℃; water salinity can be 29, 30, 31, or 32; pH value can be 8.1 or 8.2; dissolved oxygen can be 6 mg / L; light intensity can be 1100 lux, 1200 lux, 1300 lux, or 1400 lux; and water flow rate can be 55 L / min, 65 L / min, or 75 L / min. During the intensive cultivation period, it is preferable to feed the child with intensive feed twice daily. The enhanced feed preferably includes live sandworms, fresh oyster meat, vitamin C, and vitamin E; the vitamin C content is preferably 0.2% to 0.5% of the enhanced feed, but can be 0.3% or 0.4%. The vitamin E content is 0.1% to 0.2% of the enhanced feed. The daily feeding amount of the enhanced feed is preferably satiated. The feeding methods and environmental conditions during the enhanced rearing period are beneficial to promoting the gonadal maturation of the broodstock.

[0038] During the intensive breeding process, the gonadal development of wild broodstock is observed. Once the gonads reach maturity, the resulting *Large Yellow Croaker* broodstock are artificially induced to spawn and then naturally fertilized to obtain fertilized eggs. In this invention, gonadal maturity is defined as a swollen and soft abdomen with a clearly defined ovarian outline in the female broodstock, and a small amount of milky white semen flowing out when the male broodstock is gently squeezed. It is preferable to fast the fish for 1 day before artificial spawning. The preferred method for artificial spawning is to inject hormones into the *Large Yellow Croaker* broodstock in two steps. The first step involves injecting luteinizing hormone-releasing hormone (LH-A2) and human chorionic gonadotropin (hCG), while the second step involves injecting LH-A3. The preferred working concentration of LH-A2 in the first step is 10 μg / ml, and the preferred working concentration of hCG is 1000 IU / mL. The preferred working concentration of LH-A3 in the second step is 5 μg / ml. When the parent fish of the large yellow croaker (Cyprinus naanensis) are female, the preferred volume of the hormone injected in the first or second step is 0.9-1.1 mL / kg; when the parent fish are male, the preferred volume of the hormone injected in the first or second step is 0.45-0.55 mL / kg; the preferred interval between the first and second injections is 24-26 hours, but can be 25 hours; anesthesia is preferably included before the first or second injection; the anesthesia time is preferably 2-3 minutes, but can be 2.5 minutes. The artificial spawning method described in this invention is beneficial for promoting gonadal maturation in parent fish and increasing the quantity and quality of fertilized eggs. After artificial spawning, the parent fish are allowed to fertilize naturally to obtain fertilized eggs. The environmental conditions for natural fertilization are as follows: water temperature 24.5~25.5℃, salinity 28~33, pH 8.0~8.3, dissolved oxygen above 5.0mg / L, ammonia nitrogen below 0.01mg / L, light intensity 500~800lux, and a natural photoperiod of 12L:12D. Alternatively, the water temperature can be 25℃, salinity can be 29, 30, 31, or 32, pH can be 8.1 or 8.2, dissolved oxygen can be 6mg / L, and light intensity can be 600lux or 700lux. Natural fertilization includes natural mating, spawning, and fertilization. No feeding is performed during spawning. Fertilized eggs are collected 36 hours after the second injection. The environmental conditions and method for natural fertilization in this invention are beneficial for promoting natural fertilization in parent fish and improving the quantity and quality of fertilized eggs. The obtained fertilized eggs are preferably rinsed with seawater before incubation. The incubation environmental conditions are preferably the same as those for natural fertilization, and will not be repeated here. The incubation environment conditions of this invention are conducive to improving the hatching rate.

[0039] The fertilized eggs are hatched and raised to obtain fry of the large yellow croaker (Croton tigrinosa). In this invention, the water temperature for fry raising is preferably 24.5~25.5℃, and can be 25℃. The fry raising includes a larval raising stage and a fry raising stage; the water in the larval raising stage contains Chlorella; the water in the fry raising stage contains Chlorella, photosynthetic bacteria, and Bacillus thuringiensis. The Chlorella, photosynthetic bacteria, and Bacillus thuringiensis can increase the oxygen content in the water, purify the water, inhibit harmful microorganisms, and improve the immunity of the fry. The fry raised preferably include larvae aged 4~7 days, fry aged 8~20 days, fry aged 21~35 days, and fry aged 36~40 days; the initial density of the 4~7 day old larvae is 0.7 million fry / m³. 3 The fish fry cultivation method described in this invention is beneficial for promoting the growth of fry and larvae, improving the survival rate of fry, and facilitating the production of large artificially bred populations of large yellow croaker fry.

[0040] During the 4-7 day old larval stage, *Brachystomata* rotifers were used as feed, and feeding was conducted three times daily at fixed times: 7:30 AM, 12:00 PM, and 5:00 PM. The rotifers were fortified with concentrated *Chlorella* for 12 hours before feeding. The total daily feed amount was dynamically adjusted based on the larval density, feeding status, and rotifer density in the water, maintaining a rotifer density of 5-10 cells / mL to ensure a continuous supply of feed and feeding efficiency. The proportions of the three feedings were: 50% for the first feeding, 20% for the second, and 30% for the third. An appropriate amount of *Chlorella* was added daily to achieve a concentration of 4 × 10⁻⁶. 5 Cells / mL ~6×10 5 Cells / mL, which can be 5 × 10 5 For 8-20 day old fry, based on the feeding habits of *Large Yellow Croaker* and the matching of fry mouth size with feed size, copepod nauplii were selected as feed, and fed three times a day at 7:30 AM, 12:00 PM, and 5:00 PM. Before feeding, the fry were rinsed 3-5 times with natural seawater, and samples were taken to observe their vitality. If the copepods showed poor vitality or high mortality, they should not be fed. The daily feed amount was dynamically adjusted according to fry density, feeding status, and water quality, maintaining a copepod nauplii density of 2-5 individuals / mL. The three feeding amounts were 40%, 30%, and 30% of the daily feed, respectively. The preferred concentration of photosynthetic bacteria was 1×10⁻⁶. 4 ~3×10 4 CFU / ml, which can be 2×10 4 The optimal concentration of Bacillus thuringiensis is 100 × 10⁻⁶ CFU / mL. 4 ~200×10 4 CFU / ml, which can be 150×10 4CFU / ml. For fry aged 21-35 days, based on the feeding habits of the large yellow croaker (Cyprinus nauplius) and the matching of fry mouth size with feed size, Artemia nauplii were used as feed, fed three times daily. The optimal concentration of photosynthetic bacteria was 1×10⁻⁶. 4 ~3×10 4 The optimal concentration of Bacillus thuringiensis for use is 100 × 10⁻⁶ CFU / ml. 4 ~300×10 4 CFU / ml. During the 36-40 day old fry stage, the main feed consists of Artemia nauplii and a special formulated feed for large yellow croaker fry, fed four times daily at 7:30, 11:30, 15:30, and 19:00. The feeding amount should be based on the fry reaching a state of satiety after feeding. Observe the feeding situation and adjust the feed ratio and amount as needed to promote a smooth transition from natural food to formulated feed. The special formulated feed for large yellow croaker fry was purchased from Fujian Tianma Technology Group Co., Ltd.

[0041] This invention employs the described method for the artificial breeding of wild *Large Yellow Croaker* cultivars. After domestication, the survival rate of the wild *Large Yellow Croaker* cultivars exceeded 80%. A total of 426.6g of fertilized eggs were collected after artificial spawning and natural fertilization, with a total egg count of approximately 455,000 and a fertilized egg count of approximately 264,000, resulting in a fertilization rate of 58%. After hatching, the initial hatching number of fry was approximately 169,000, with a hatching rate of 64%. At 40 days of age, the number of fry was approximately 98,000, with a survival rate of 57.9%. It is evident that the method of this invention achieves high fertilization and hatching rates, and can yield a large artificially bred population of *Large Yellow Croaker* fry. This invention provides an effective method for the large-scale farming of *Large Yellow Croaker* cultivars.

[0042] To further illustrate the present invention, the solutions provided by the present invention will be described in detail below with reference to embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] Example 1

[0044] A method for artificially breeding wild large yellow croaker (Cyprinus naan) is described below:

[0045] 1. Collection and domestication of wild *Large Yellow Croaker* broodstock: During the neap tides of September and October in the lunar calendar, wild *Large Yellow Croaker* broodstock are harvested in the waters near Naozhou Island, Zhanjiang, Guangdong Province, along their migration routes using purse seine nets (minimum mesh size greater than 5cm). The harvested wild *Large Yellow Croaker* are transferred to the live water tank of fishing boats and transported back to the harbor. From there, they are slowly transferred in plastic buckets with water to specialized live fish transport vehicles. Environmental control during transport: The transport vehicles are oxygenated to a level above 6mg / L with pure oxygen. The water temperature is controlled at 22±0.5℃ using refrigeration equipment. The water is supplemented with the anesthetic clove oil (containing 10% eugenol) at 5mg / L and the anti-stress agent γ-aminobutyric acid (GABA) at 0.05mg / L. The transport time to the aquaculture farm does not exceed 1 hour.

[0046] Upon arrival at the fish farm, use a hand net to slowly scoop the fish into a plastic bucket half-filled with water, and then gently transfer them to an indoor rearing pond (4m long × 4m wide × 1.5m high). Esterified vitamin C and enrofloxacin powder are pre-sprinkled into the pond water at a dosage of 5mg of esterified vitamin C per cubic meter of water and 15mg of enrofloxacin powder per cubic meter of water. The fish are temporarily held in the pond for 7 days, with the following water quality conditions during this period: water temperature 22±0.5℃, salinity 19, pH 8.0~8.3, dissolved oxygen 5.0mg / L, ammonia nitrogen 0.02mg / L, and light intensity 1200lux. During this period, drain the water to a depth of 20cm every afternoon, scrub the surface and bottom of the pond, and then refill with filtered and settled natural seawater and freshwater to a level of 1.5m, maintaining the salinity at 19. Add 12mg of enrofloxacin powder per cubic meter of water. Do not feed the fish during this period.

[0047] Acclimation and rearing were conducted in the breeding ponds from day 8 to day 30. The environmental conditions for acclimation and rearing were: water temperature 22±0.5℃, salinity 30, pH 8.0~8.3, dissolved oxygen above 5.0 mg / L, ammonia nitrogen below 0.01 mg / L, and light intensity 1200 lux. From day 8 to day 14, fresh fish meat was fed at fixed times at 8:00 AM and 4:00 PM daily. The fish meat was fresh marine fish purchased that day, such as mackerel or blue trevally, which was cleaned, had its back muscle removed, disinfected with iodine, and cut into pieces before feeding. The fish meat was fed slowly to entice the parent fish to feed, and each feeding lasted for 1 hour. From day 15 to day 30, after observing that the parent fish were able to feed normally, they were fed in a "slow-fast-slow" manner, at fixed times at 8:00 AM and 4:00 PM daily, with fresh fish meat accounting for 4% of the parent fish's body weight. Each feeding lasted for 1 hour. During the acclimatization period, 0.5 hours after each feeding, any remaining fish meat was siphoned off, and waste water was removed and changed. The water was drained to a depth of 20cm, and then filtered natural seawater was added until the water level reached 1.5m. At the end of the acclimatization period, the survival rate was 81.5%.

[0048] 2. Broodstock Enhancement and Rearing: After domestication, broodstock nutritional enhancement begins. Environmental conditions for broodstock enhancement and rearing: Based on the physiological and ecological developmental characteristics of the large yellow croaker (Culter alburnus), a gradual temperature increase method is adopted. The water temperature is gradually increased from 22±0.5℃ to 25±0.5℃ in a daily increment of 0.5℃, and maintained at 25±0.5℃. The optimal conditions are: salinity 30, pH 8.0~8.3, dissolved oxygen above 5.0mg / L, ammonia nitrogen below 0.01mg / L, light intensity 700 lux, natural photoperiod 12L:12D, and water flow rate 60L / min. The nutritionally enhanced feed consists of live sandworms and fresh oyster meat, with added vitamin C (0.4% of feed weight) and vitamin E (0.2% of feed weight). Live sandworms are fed at 8:00 AM, and fresh oyster meat is fed at 4:00 PM, with each feeding being a full-feeding session. During the intensive rearing of broodstock, waste was removed after feeding, and after a 100% water change, the water flow rate was maintained at 60 L / min. Nutritional fortification and temperature-increased maturation were implemented to promote gonadal development in the broodstock. The feeding and activity levels of the broodstock were observed daily during this period.

[0049] 3. Artificial Induction of Spawning and Fertilization: Observe the gonadal development of wild broodstock. When the abdomen of the female broodstock is swollen and soft, the ovary outline is obvious, and a small amount of milky white semen flows out when the abdomen of the male broodstock is gently squeezed, artificial spawning can be induced. Fast the fish for 1 day before spawning. Select healthy and vigorous broodstock. Anesthetize 100 male broodstock (over 200g) and 200 female broodstock (over 400g) with eugenol (10mg / L) and inject artificial spawning hormone at the base of the pectoral fin. Use a two-stage injection method. The first injection uses a mixed hormone of luteinizing hormone-releasing hormone A2 (LRH-A2) and human chorionic gonadotropin (HCG) (diluted with physiological saline to prepare a mixed hormone of HCG 1000 IU / mL and luteinizing hormone-releasing hormone analog No. 2 10μg / mL). The injection dosage is 1mL per 1000g female fish and 0.5mL per 1000g male fish. Artificial spawning was induced on November 26, 2025, from 9:00 AM to 11:00 AM, with the anesthesia time for the broodstock controlled to be 2 minutes. A second artificial spawning was induced on the morning of November 27, 2025. 24 hours after the first induced spawning, luteinizing hormone-releasing hormone A3 (LRH-A3) was used, diluted with physiological saline to a concentration of 5 μg / ml. The injection dosage was 1 mL per 1000g female fish and 0.5 mL per 1000g male fish. This oxytocin was purchased from Ningbo Sansheng Biotechnology Co., Ltd. Immediately after injection, the broodstock were slowly placed into the spawning pond (5m long × 4m wide × 1.5m high), and then allowed to mate, spawn, and fertilize naturally. Spawning pond environmental conditions: water temperature 25±0.5℃, salinity 30, pH 8.0~8.3, dissolved oxygen above 5.0mg / L, ammonia nitrogen below 0.01mg / L, light intensity 700 lux, natural photoperiod 12L:12D. The broodstock were not fed during the spawning period. Thirty-six hours after the second injection of oxytocin, starting at 9 p.m. on November 28, naturally fertilized eggs were collected from the spawning pool using an 80-mesh silk screen along the edge of the pool. A total of 426.6g of fertilized eggs were collected.

[0050] Randomly sample and count the total number of eggs, and calculate the fertilization rate according to Formula I.

[0051] Fertilization rate = (Number of fertilized eggs / Total number of eggs) × 100% (Formula I)

[0052] The total number of eggs counted was approximately 455,000, with approximately 264,000 fertilized eggs, resulting in a fertilization rate of 58%.

[0053] 4. Fertilized Egg Hatching: After rinsing the collected fertilized eggs multiple times with seawater, they are placed in a 1 cubic meter conical-bottom fiberglass hatching tank and aerated for 30 minutes. Aeration is then stopped, and the tank is left to stand for 10-15 minutes to remove any bad eggs and impurities that have settled to the bottom. Hatching is carried out in the tank with aeration, maintaining a water temperature of 25±0.5℃, salinity of 30, pH of 8.0-8.3, dissolved oxygen above 5.0 mg / L, ammonia nitrogen below 0.01 mg / L, light intensity of 700 lux, and a natural photoperiod of 12L:12D. Embryos hatch after 26 hours. After hatching, aeration is stopped, the bottom valve of the hatching tank is opened to drain the sediment, and 50% of the water is replaced. The newly hatched larvae are then transferred to a nursery pond for further rearing. A random sample of the newly hatched larvae is counted, and the hatching rate is calculated using Formula II.

[0054] Hatching rate = (Number of newly hatched fry / Number of fertilized eggs) × 100% (Formula II)

[0055] The number of newly hatched fry was approximately 169,000, with a hatching rate of 64%.

[0056] 5. Indoor Cement Pond Seedling Cultivation: In the seedling cultivation pond (4m long × 4m wide × 1.5m high), one aeration stone is placed per square meter for aeration. The aeration stones, air pipes, and pond walls are disinfected with potassium permanganate and then rinsed clean. Then, filtered natural seawater is added, initially filling the pond with 1m of seawater. Newly hatched fry are then transferred to the cultivation pond at a density of 7,000 fry / m². 3 Under water temperature conditions of 25±0.5℃,

[0057] For 4-7 day old fry, the diet consists of Brachionus folds, fed at 7:30 AM, 12:00 PM, and 5:00 PM. Based on the feeding characteristics of the fry, the total daily feed amount is dynamically adjusted according to the fry density, feeding status, and rotifer density in the water, maintaining a rotifer density of 8 rotifers / mL to ensure continuous feed supply and feeding efficiency. The rotifers are nutritionally fortified with concentrated Chlorella for 12 hours before feeding. The feeding amounts at each time point are 50%, 20%, and 30% of the daily feed amount, respectively. Additionally, an appropriate amount of Chlorella is added daily to achieve a concentration of 5 × 10⁻⁶. 5 Species / mL. Based on the nutritional and palatability requirements of the first-day larvae of the large yellow croaker from Naozhou, Brachionus foldis (200~300μm) was selected as the first food, which is suitable for their mouth size and can meet the nutritional needs of the larvae. During the larval stage of 4~7 days old, 5cm of filtered seawater was added daily.

[0058] For fry aged 8-20 days, feed them with copepod nauplius larvae. Do not feed if the copepods are weak or have a high mortality rate. Rinse the fish 3-5 times with natural seawater before feeding, and then take samples to observe their vitality. Feeding times are 7:30 AM, 12:00 PM, and 5:00 PM, with the amount fed at each time being 40%, 30%, and 30% of the daily feed amount, respectively. Adjust the amount according to the feeding situation. Rinse the fish 3-5 times with natural seawater before feeding, and then take samples to observe their vitality. Do not feed if the copepods are weak or have a high mortality rate. The daily feed amount is dynamically adjusted according to the fry density, feeding status, and water quality to maintain a copepod nauplius larvae density of 3 larvae / mL. Begin siphoning the bottom debris at 9:00 AM, then drain 10cm of water using a siphon, and then add 10cm of settled seawater. Add an appropriate amount of Chlorella daily to achieve a concentration of 3×10⁻⁶. 5 CFU / mL. Photosynthetic bacteria and Bacillus thuringiensis were added, with a concentration of 2 × 10⁶ CFU / mL for photosynthetic bacteria. 4 CFU / ml, the concentration of Bacillus thuringiensis used is 100×10⁻⁶ CFU / ml. 4 CFU / ml.

[0059] Fish fry aged 21-35 days were fed Artemia larvae. Feeding times were 7:30, 11:30, 15:30, and 19:00, with feeding amounts at each time point being 40%, 30%, and 30% of the daily feed intake, respectively. The daily feed intake was adjusted according to feeding behavior, maintaining an Artemia larvae density of 2 larvae / mL in the rearing tank. Starting at 9:00 AM, waste was siphoned from the bottom of the tank, followed by 10cm of siphoned water, and then 10cm of settled seawater was added. Photosynthetic bacteria and Bacillus thuringiensis were introduced, with the photosynthetic bacteria concentration at 2×10⁻⁶. 4 CFU / ml, the concentration of Bacillus thuringiensis used is 150×10⁻⁶. 4 CFU / ml.

[0060] From 36 to 40 days old, fry are acclimatized using a combination of formulated feed for large yellow croaker larvae and artichokes. Feeding times are 7:30, 11:30, 15:30, and 19:00, four times a day, with the amount fed until the fish are satiated. From 36 to 38 days old, the diet consists mainly of artichokes, supplemented with formulated feed. The ratio can be controlled at 70%–80% artichokes and 20%–30% formulated feed. From 39 to 40 days old, gradually increase the proportion of formulated feed and decrease the proportion of artichokes, adjusting to 20%–30% artichokes and 70%–80% formulated feed. At 9:00, 12:00, and 18:00, remove sludge from the bottom of the pond, then drain 10cm of water using a siphon, followed by adding 10cm of settled seawater. Photosynthetic bacteria and Bacillus thuringiensis are introduced, with a concentration of 5×10⁻⁶ for the photosynthetic bacteria. 4 CFU / ml, the concentration of Bacillus thuringiensis used is 300×10⁻⁶.4 CFU / ml.

[0061] Randomly sample and count the number of 40-day-old fry in the rearing pond, and calculate the survival rate of the fry according to Formula III.

[0062] Fish fry survival rate = (Number of surviving fry at 40 days old / Number of newly hatched fry) × 100% Formula III

[0063] In addition, 50 fish were randomly sampled from the rearing pond to measure their total length and weight to assess the fry's overall length and weight. Care was taken during the statistical and measurement process to avoid damaging the fry. After the measurements were completed, the fry were returned to the rearing pond for further rearing. At 40 days of age, the fry had an average total length of 3.25 cm and an average weight of 0.27 g. The total number of fry was approximately 98,000, with a survival rate of 57.9%.

[0064] From 41 days old, the fish fry are fed exclusively with a specialized formulated feed for large yellow croaker, at 8:00 AM, 12:00 PM, and 5:00 PM, three times a day, with the amount fed until the fish are fully fed. At 9:00 AM and 6:00 PM, siphon off the bottom debris, then drain 20cm of water using a siphon, followed by adding 20cm of settled seawater. Photosynthetic bacteria and Bacillus thuringiensis are introduced, with the photosynthetic bacteria used at a concentration of 5 × 10⁻⁶. 4 CFU / ml, the concentration of Bacillus thuringiensis used is 200×10⁻⁶. 4 CFU / ml.

[0065] Comparative Example 1

[0066] The artificial breeding method for wild Naozhou large yellow croaker was the same as in Example 1, except that the water temperature for temporary rearing of the wild Naozhou large yellow croaker parent fish during collection and domestication was 28℃. After domestication, the survival rate of the wild Naozhou large yellow croaker was calculated to be 41%.

[0067] A total of 220g of fertilized eggs were collected after artificial spawning and fertilization. The total number of eggs was approximately 214,000, with approximately 79,000 fertilized eggs, resulting in a fertilization rate of 36.9%. After hatching, the hatching rate was 45.5%. At 40 days of age, approximately 11,000 fry were identified, with a survival rate of 32.8%.

[0068] Comparative Example 2

[0069] The method for collecting and acclimatizing wild Naozhou large yellow croaker broodstock was the same as in Example 1, except that the light intensity during acclimatization was 2500 lux. At the end of acclimatization, the survival rate of the wild Naozhou large yellow croaker broodstock was calculated to be 42.6%.

[0070] A total of 312.6g of fertilized eggs were collected after artificial spawning and fertilization. The total number of eggs was approximately 313,000, with approximately 110,000 fertilized eggs, resulting in a fertilization rate of 35.4%. After hatching, the hatching rate was 42.6%. At 40 days of age, approximately 17,000 fry were identified, with a survival rate of 35.8%.

[0071] Comparative Example 3

[0072] The method for collecting and domesticating wild Naozhou large yellow croaker broodstock is the same as in Example 1, except that vitamin C and vitamin E are not added to the feed for the enhanced breeding of broodstock.

[0073] A total of 389.4g of fertilized eggs were collected after artificial spawning and fertilization. The total number of eggs was approximately 415,000, with approximately 175,000 fertilized eggs, resulting in a fertilization rate of 42.5%. After hatching, the hatching rate was 45.7%. At 40 days of age, approximately 41,000 fry were identified, with a survival rate of 50.9%.

[0074] Comparative Example 4

[0075] The method for collecting and domesticating wild Naozhou large yellow croaker parent fish is the same as in Example 1, except that the light intensity for hatching fertilized eggs is 2000 lux.

[0076] A total of 405.4g of fertilized eggs were collected after artificial spawning and fertilization. The total number of eggs was approximately 430,000, with approximately 220,000 fertilized eggs, resulting in a fertilization rate of 51%. After hatching, the hatching rate was 32.8%. At 40 days of age, approximately 28,700 fry were identified, with a survival rate of 39.8%.

[0077] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for the artificial breeding of wild large yellow croaker (Cyprinus naanensis), characterized in that, Includes the following steps: Wild Naozhou yellow croaker is domesticated and then intensively cultivated until its gonads mature. The resulting parent fish are then artificially induced to spawn and naturally fertilized to obtain fertilized eggs. These fertilized eggs are then hatched and raised to produce Naozhou yellow croaker fry. The artificial spawning method involves injecting hormones into the parent fish of the large yellow croaker in two steps. The first step of the injection includes luteinizing hormone-releasing hormone A2 and human chorionic gonadotropin, and the second step of the injection includes luteinizing hormone-releasing hormone A3. The interval between the first and second injections is 24-26 hours. When the parent fish of the large yellow croaker from Naozhou are female, the volume of hormone injected in the first step or the second step is 0.9~1.1mL / kg. When the parent fish of the large yellow croaker from Naozhou are male, the volume of hormone injected in the first step or the second step is 0.45~0.55mL / kg. The working concentration of luteinizing hormone-releasing hormone A2 and the working concentration of human chorionic gonadotropin (hCG) injected in the first step are 10 μg / ml and 1000 IU / mL, respectively. The working concentration of luteinizing hormone-releasing hormone A3 in the second step of injection is 5 μg / ml; The seedling cultivation includes a larvae cultivation stage and a fry cultivation stage; the water in the larvae cultivation stage contains Chlorella vulgaris; the water in the fry cultivation stage contains Chlorella vulgaris, photosynthetic bacteria, and Bacillus thuringiensis. The seedlings cultivated include fry aged 4-7 days, fry aged 8-20 days, fry aged 21-35 days, and fry aged 36-40 days. For 4-7 day old fry, feed them with Brachionus folds, at a rate of 5-10 Brachionus folds / mL, and maintain a Chlorella concentration of 4 × 10⁻⁶. 5 ~6×10 5 cells / mL; For fry aged 8-20 days, the feed should include copepod nauplii, at a rate of 2-5 copepod nauplii / mL, and a Chlorella concentration of 2×10⁻⁶. 5 ~4×10 5 The concentration of photosynthetic bacteria was 1×10⁶ cells / mL. 4 ~3×10 4 CFU / ml, the concentration of Bacillus thuringiensis used is 100×10⁻⁶ CFU / ml. 4 ~200×10 4 CFU / ml; Fish fry aged 21-35 days should be fed with Artemia nauplii; Feed for 36-40 day old fry includes Artemia nauplii and formulated feed for large yellow croaker larvae; The initial density of the 4-7 day old fry was 0.7 million fry / m³. 3 .

2. The method according to claim 1, characterized in that, The acclimatization environmental conditions are: water temperature 21.5~22.5℃, pH value 8.0~8.3, dissolved oxygen above 5.0mg / L, ammonia nitrogen below 0.01mg / L, and light intensity 1000~1500 lux; The acclimatization includes temporary rearing and acclimatization cultivation; the temporary rearing period is 5-7 days; the salinity of the water used for temporary rearing is 18-22; The domestication and cultivation period is 20-26 days; the salinity of the water used for domestication and cultivation is 28-33; fresh marine fish are fed twice a day during the domestication and cultivation period; the daily feeding amount of fresh marine fish is 3%-5% of the body weight of wild Naozhou large yellow croaker.

3. The method according to claim 1, characterized in that, The environmental conditions for enhanced cultivation are as follows: water temperature gradually increases from 21.5~22.5℃ to 24.5~25.5℃ at a rate of 0.5℃ per day; water salinity is 28~33; pH value is 8.0~8.3; dissolved oxygen is above 5.0mg / L; ammonia nitrogen is below 0.01mg / L; light intensity is 500~800 lux; and water flow rate is 50~80L / min.

4. The method according to claim 1, characterized in that, During the intensive breeding period, the feed was provided twice daily. The fortified feed includes live sandworms, fresh oyster meat, vitamin C, and vitamin E; the vitamin C accounts for 0.2% to 0.5% of the fortified feed by mass, and the vitamin E accounts for 0.1% to 0.2% of the fortified feed by mass; the daily feeding amount of the fortified feed is based on satiated feeding.

5. The method according to claim 1, characterized in that, Anesthesia is also included before the first or second injection; the anesthesia time is 2-3 minutes.

6. The method according to claim 1, characterized in that, The environmental conditions for natural fertilization or hatching are as follows: water temperature 24.5~25.5℃, water salinity 28~33, pH value 8.0~8.3, dissolved oxygen above 5.0mg / L, ammonia nitrogen below 0.01mg / L, and light intensity 500~800lux.

7. The method according to any one of claims 1 to 6, characterized in that, The environmental conditions for seedling cultivation are: water temperature 24.5~25.5℃.