Method for off-season breeding of golden pompano

Abstract

The application discloses a kind of gold pompano reverse season breeding method, it is related to aquaculture technical field.The method includes selecting the parent for gold pompano reverse season breeding, using reinforcing agent to the ovary of female parent is strengthened, to the parent is low temperature accumulated temperature, to the parent is handled, using hormone to control the gonad development state of parent, fertilization is carried out, obtains fertilized egg, fertilized egg hatches etc.Steps.By the treatment such as strengthening, low temperature accumulated temperature, cutting fin of parent fish, the gonad development state of parent fish is accurately controlled, the reverse season breeding of gold pompano is realized, the reproductive efficiency and fry quality of gold pompano are improved, solve the problem that existing gold pompano breeding is seasonally limited, with good economic benefits and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology, specifically relating to a method for off-season breeding of golden pomfret. Background Technology

[0002] Golden pomfret belongs to the genus *Trachinotus* of the family Carangidae in the order Perciformes. It is a warm-water, mid-to-upper-level migratory fish. It has a flattened, oval body covered with silvery-white scales, while its fins and tail are golden. Adult golden pomfret can reach 50 cm in length, with the largest individuals weighing over 23 kg. Geographically, this species mainly inhabits the tropical and subtropical warm waters of the western Pacific and Indian Oceans, adapted to the warm marine environment. Golden pomfret is also an important marine economic fish in my country, with an annual production exceeding 300,000 tons, making it the largest marine aquaculture fish species in my country. Large-scale marine aquaculture of golden pomfret is mainly carried out along the coast of South China (Guangdong, Guangxi, and Hainan) and Southeast Asia. Its short cultivation cycle results in significant economic benefits and stable market demand. Golden pomfret has tender and firm flesh, and its flavor changes little after freezing. It has few intramuscular bones, high protein content, low fat content, and is rich in unsaturated fatty acids and minerals such as calcium and phosphorus, making it both edible and nutritious.

[0003] The breeding season for golden pomfret is from February to July each year, during which time the entire industry receives all the necessary seedlings. However, during the golden pomfret farming process, extreme weather such as typhoons and diseases frequently occur, leading to large-scale losses of farmed golden pomfret and necessitating restocking. Some farmers intend to purchase seedlings for overwintering in autumn and winter in order to bring them to market earlier and obtain higher profits. In addition, Southeast Asian countries have suitable temperatures throughout the year, which fall within the suitable temperature range for golden pomfret to survive, and they also desire a stable supply of seedlings. Based on these needs, it is necessary to develop off-season golden pomfret seedlings.

[0004] Currently, although some progress has been made in off-season breeding methods for fish, detailed reports on off-season breeding of golden pomfret have not yet been found. As a warm-water, mid-to-upper-level migratory fish, the golden pomfret has unique biological characteristics and ecological requirements, and existing off-season breeding methods for other fish are not entirely applicable to it. Therefore, there is an urgent practical need to develop a highly efficient and easy-to-operate off-season breeding method specifically for golden pomfret. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for off-season breeding of golden pomfret, breaking the seasonal restrictions on the breeding of golden pomfret, improving the breeding efficiency and seedling quality of golden pomfret, achieving a stable supply of golden pomfret, and providing important support for the development of the golden pomfret industry.

[0006] The technical solution of this invention mainly includes the following:

[0007] A method for off-season breeding of golden pomfret includes the following steps:

[0008] (1) Select parent stock for off-season breeding of golden pomfret;

[0009] (2) Ovarian enhancement of the mother fish was achieved by feeding her with fortified chilled aquatic products;

[0010] (3) Utilize north-south transportation to accumulate low-temperature temperature for the parent plants;

[0011] (4) Fin clipping treatment was performed on the parent plants after low-temperature accumulation;

[0012] (5) Use hormones to regulate the developmental state of the parent gonads, promote gonadal maturation and ovulation;

[0013] (6) Fertilization is carried out to obtain fertilized eggs, the fertilized eggs hatch, and fish fry are obtained.

[0014] Preferably, in step (1), the parent species include a maternal parent and a paternal parent, wherein the maternal parent is selected from the oval pomfret or its hybrids, and the hybrids include the Brunelles brevicornu. Trachinotus blochii and oval pomfret Trachinotus ovatus The hybrid species, wherein the male parent includes the oval pomfret.

[0015] Preferably, in step (1), the parent fish are healthy fish with normal body shape, over 4 years old, and gonads developed to stage 3 or more.

[0016] Preferably, in step (2), in Hainan, after the fish have laid eggs from February to May, they need to undergo continuous ovarian strengthening to create conditions for subsequent off-season breeding.

[0017] Preferably, the enhanced chilled aquatic product contains a fortifying agent, which contains 5 g / L vitamin E, 1 g / L vitamin A, 20 g / L lecithin, 10 g / L bile acids, 20 g / L cholesterol, 10 g / L Schizochytrium powder, 200 g / L glycerol, 1 g / L zinc chloride, 5 g / L vitamin C, 2 g / L arginine, 2 g / L lysine, 20 g / L monoglycerides, and water. By adding the fortifying agent to chilled aquatic products for enhanced cultivation, the reproductive performance of the golden pomfret parent can be significantly improved, providing higher-quality parent stock for off-season breeding and increasing the success rate of off-season breeding. The fortifying agent contains fat-soluble and water-soluble substances. The fat-soluble substances are vitamin E, vitamin A, lecithin, bile acids, cholesterol, and Schizochytrium powder; the water-soluble substances are zinc chloride, vitamin C, arginine, and lysine. The fat-soluble substance is dissolved in glycerol, and the water-soluble substance is dissolved in water. The glycerol solution containing the fat-soluble substance and the aqueous solution containing the water-soluble substance are mixed, 20g of monoglyceride is added, and the volume is adjusted to 1000mL with pure water. The mixture is stirred for 24 hours and then placed at 4℃ to obtain the fortifying agent.

[0018] Preferably, in step (2), the preparation method of the enhanced chilled aquatic products is as follows: 100L of fortifier is mixed with 100g of fish meal, and 200g of the mixture is mixed with 10kg of chilled aquatic products, that is, the diced chilled squid and chilled bonito are wrapped, and the mixture is prepared and used daily. After being wrapped evenly, the mixture is fed to the fish at a feeding amount of 2% to 5% of the fish's body weight. The fish meal includes eel meal, and the chilled aquatic products include squid and bonito. The mass ratio of squid to bonito is 1:3.

[0019] Preferably, in step (3), the sex of the golden pomfret broodstock is determined by ultrasound. After the peak breeding season, the parent fish are injected with human chorionic gonadotropin once in May. The injection dose for female fish is 800-1000 units / kg, and the injection dose for male fish is 500-600 units / kg. 3-6 days after the injection, the fish are prepared for transportation. Two days before the transportation, the amount of chilled aquatic products fed is reduced to 0.5%-1% of the body weight. At this time, 100mg of L-carnitine is mixed in every kilogram of chilled aquatic products. The golden pomfret is transported to areas with higher latitudes (above 21°) and water temperatures below 26°C, such as Guangdong, Fujian, and Guangxi (the latitude of these areas is 21-28°), for low-temperature heat accumulation treatment.

[0020] Preferably, in step (4), the golden pomfret undergoes fin trimming to ensure its gonads maintain good development. The fin trimming method includes the following steps: cutting off 1 / 3 to 1 / 2 of the upper or lower part of the tail fin or cutting off 2 / 3 of the dorsal fin; after trimming the fins, applying petroleum jelly ointment containing 1% (w / w) erythromycin; and after the wounds heal, returning the pomfret to the fish raft for normal aquaculture.

[0021] Preferably, before the low-temperature accumulation, both female and male fish are injected with human chorionic gonadotropin once, with the injection dose for female fish being 800-1000 units / kg and the injection dose for male fish being 500-600 units / kg. In step (5), after being transferred to a higher latitude region, the fish are continuously fed enhanced chilled aquatic products. Female fish are fed enhanced chilled aquatic products containing 3000-6000 units of follicle-stimulating hormone per kilogram every 5 days, and male fish are fed enhanced chilled aquatic products containing 2000-2500 units of human chorionic gonadotropin per kilogram every 5 days to promote the redevelopment of the gonads. Off-season breeding from August to October is carried out in higher latitude regions (Guangdong, Guangxi, Fujian), and off-season breeding from October to December is carried out in lower latitude regions (Hainan). The spawning induction method is as follows: female and male fish are mixed and raised. 2 μg of luteinizing hormone-releasing hormone is injected into both female and male fish per kilogram of body weight. 24 hours later, 3 μg of luteinizing hormone-releasing hormone is injected. Spawning will occur 24 hours later, and fertilization will occur naturally.

[0022] Before and after the accumulation of low temperatures, synergistic hormonal regulation is necessary to ensure optimal gonadal development. The types, dosages, and timing of hormones used in this synergistic regulation process are rigorously scientifically determined. Before the accumulation of low temperatures, a single injection of human chorionic gonadotropin (hCG) can initially stimulate the developmental potential of the gonads in both male and female fish. After the accumulation of low temperatures, feeding with fortified chilled aquatic products and adding specific hormones further precisely regulates gonadal development. This synergistic hormonal regulation not only effectively improves the gonadal development level of golden pomfret but also makes the reproductive process more stable and efficient. By precisely controlling hormone use, golden pomfret can successfully complete its reproductive process even under off-season conditions, providing strong technical support for a year-round supply. Simultaneously, this regulation method fully considers the environmental differences at different breeding periods and latitudes, adjusting the types and dosages of hormones to achieve optimal reproductive results.

[0023] The hatching rate of off-season fertilized eggs is lower than that of fertilized eggs in the normal season. In step (6), the following method is preferred to improve the fertilization rate: 2-5 kg ​​of fertilized eggs are treated in a 1-ton incubation tank. Natural seawater is added to the incubation tank, and then 100g of activated carbon with an iodine value of 500-1000 is added per ton of water to remove ammonia nitrogen and other organic matter and prevent the formation of toxic substances such as chloramine after the addition of disinfectant. Sodium hypochlorite is added at a final concentration of 0.1ppm to disinfect and soften the eggshell. The incubation temperature is 24℃~30℃. The salinity is appropriately increased. During the incubation process, the salinity is 33‰~36‰ to accelerate the settling rate of unfertilized or poorly developed eggs. Dead eggs are released one hour after the end of the blastocyst stage, gastrula stage, myosarcoma formation stage, and heartbeat stage to prevent dead eggs from affecting other good fertilized eggs.

[0024] The beneficial effects of this invention are:

[0025] This invention, through treatments such as ovarian enhancement, low-temperature accumulation, fin clipping, and hormone regulation, can induce golden pomfret to spawn and reproduce outside the natural breeding season, breaking the seasonal constraints on golden pomfret breeding and achieving a stable supply of fry throughout the year to meet market demand at different times.

[0026] This invention improves fertilization and hatching rates by precisely controlling the incubation conditions of parent fish and scientifically selecting incubation methods, thereby increasing the number of fish fry produced. Attached Figure Description

[0027] Figure 1 : Diagram showing the fin trimming of a golden pomfret. 1, 2, and 3 in the diagram indicate the trimmed fin areas. Detailed Implementation

[0028] To facilitate a better understanding of the technical content of this invention by those skilled in the art, the invention will be further described in detail below through specific embodiments and accompanying drawings.

[0029] Unless otherwise specified, all reagents and agents used in the following examples are commercially available products, and all experimental methods are conventional methods. Salinity refers to the ratio of the mass of dissolved substances in seawater to the mass of seawater.

[0030] Example 1

[0031] Off-season cultivation method:

[0032] The parent stock consisted of 200 healthy, 4-year-old or older oval pomfret females with normal body shape and gonadal development, 200 females (crossbred with *Ailuropoda brevicornu*), and 200 males (both oval pomfret). Each group consisted of 100 females and 50 males. The ovaries of the female golden pomfret were all in stage 3 or more of maturity. In Hainan, after spawning in May, the fish underwent continuous fertilization. The fertilization agent was prepared as follows:

[0033] Fat-soluble substances (5g Vitamin E, 1g Vitamin A, 20g lecithin, 10g bile acids, 20g cholesterol, 10g Schizochytrium powder) are dissolved in 200g glycerol. Water-soluble substances (1g zinc chloride, 5g Vitamin C, 2g arginine, 2g lysine) are diluted to 200g pure water. The glycerol solution containing the fat-soluble substances and the aqueous solution containing the water-soluble substances are mixed together, 20g monoglyceride is added, and the volume is diluted to 1000mL with pure water. The mixture is stirred for 24 hours and stored at 4℃ for later use. Before feeding, 100g of eel powder is mixed with every 100L of fortifier, and 200g of the mixture is mixed with 10kg of chilled seafood, i.e., the cut chilled squid and chilled bonito are coated. The mass ratio of squid to bonito is 1:3. The mixture is prepared fresh daily, coated evenly, and fed at a rate of 4% of the body weight.

[0034] In May, both female and male pomfret were injected with human chorionic gonadotropin (hCG) once. The injection dose for females was 1000 units / kg (800-1000 units / kg is acceptable), and the injection dose for males was 600 units / kg (500-600 units / kg is acceptable) to prevent gonadal degeneration. Six days after injection, preparations were made for transport. Two days before transport, the amount of fortified chilled seafood in the feed was reduced to 1% (0.5%-1% is acceptable), and 100 mg of L-carnitine was mixed in with each kilogram of chilled seafood. The pomfret broodstock were transported to Zhuhai, Guangdong Province, using a transport vessel for low-temperature treatment.

[0035] Fin clipping is performed on golden pomfret broodstock to maintain healthy gonad development. The method is as follows: cut off the upper third of the tail fin of the golden pomfret, apply petroleum jelly ointment containing 1% erythromycin after fin clipping to prevent infection, and release the fish back into the fish raft for normal aquaculture after the wound has healed.

[0036] After being transferred to higher latitude areas, the fish were continuously fed fortified chilled aquatic products at a rate of 4% of their body weight. Female fish were fed every 5 days a fortified chilled aquatic product containing 5000 units (3000-6000 units are acceptable, with no significant difference in effect) of follicle-stimulating hormone per kilogram. Male fish were fed every 5 days a fortified chilled aquatic product containing 2000 units (2000-2500 units are acceptable, with no significant difference in effect) of human chorionic gonadotropin per kilogram to promote gonadal redevelopment. Spawning was induced twice: in September in Zhuhai, Guangdong, and in November in Sanya, Hainan. The induced spawning method was as follows: female and male fish were housed together. Both females and males were injected with 2 μg of luteinizing hormone-releasing hormone per kilogram of body weight. 24 hours later, 3 μg of luteinizing hormone-releasing hormone was injected again. Spawning occurred 24 hours later, and fertilization was natural. The number of spawns was recorded. Take 200 fertilized eggs and place them in a beaker at 26°C. Perform three parallel tests and calculate the hatching rate and fertilization rate of the fertilized eggs.

[0037] Off-season cultivation without hormone regulation:

[0038] The parent stock consisted of 200 healthy, 4-year-old or older oval pomfret females with normal body shape and gonadal development, 200 females (crossbred with *Ailuropoda brevicornu*), and 200 males (both oval pomfret). Each group consisted of 100 females and 50 males. The ovaries of the female golden pomfret were all in stage 3 or more of maturity. In Hainan, after spawning in May, the fish underwent continuous fertilization. The fertilization agent was prepared as follows:

[0039] Fat-soluble substances (5g Vitamin E, 1g Vitamin A, 20g lecithin, 10g bile acids, 20g cholesterol, 10g Schizochytrium powder) are dissolved in 200g glycerol. Water-soluble substances (1g zinc chloride, 5g Vitamin C, 2g arginine, 2g lysine) are diluted to 200g pure water. The glycerol solution containing the fat-soluble substances and the aqueous solution containing the water-soluble substances are mixed together, 20g monoglyceride is added, and the volume is diluted to 1000mL with pure water. The mixture is stirred for 24 hours and stored at 4℃ for later use. Before feeding, 100g of eel powder is mixed with every 100L of fortifier, and 200g of the mixture is mixed with 10kg of chilled seafood, i.e., the cut chilled squid and chilled bonito are coated. The mass ratio of squid to bonito is 1:3. The mixture is prepared fresh daily, coated evenly, and fed at a rate of 4% of the body weight. Two days before the transfer, the amount of fortified chilled aquatic products fed to the fish was reduced to 1% (0.5% to 1% is acceptable), at which time 100mg of L-carnitine was mixed in per kilogram of chilled aquatic products. The golden pomfret broodstock were then transported to Zhuhai, Guangdong for low-temperature treatment using a transport vessel.

[0040] Fin clipping is performed on golden pomfret broodstock to maintain healthy gonad development. The method is as follows: cut off the upper third of the tail fin of the golden pomfret, apply petroleum jelly ointment containing 1% erythromycin after fin clipping to prevent infection, and release the fish back into the fish raft for normal aquaculture after the wound has healed.

[0041] After being transferred to higher latitude areas, the fish were continuously fed enhanced fresh aquatic products at a rate of 4% of their body weight. Spawning was induced twice: off-season breeding in September was conducted in Zhuhai, Guangdong Province, and off-season breeding in November was conducted in Sanya, Hainan Province. The spawning induction method was as follows: female and male fish were housed together. Both females and males were injected with 2 μg of luteinizing hormone-releasing hormone (LH) per kilogram of body weight. 24 hours later, 3 μg of LH was injected again. Spawning occurred 24 hours later, and fertilization occurred naturally. The number of spawns was recorded. 200 fertilized eggs were placed in a beaker at 26°C, and three replicates were performed to calculate the hatching rate and fertilization rate.

[0042] Traditional method:

[0043] The parent stock consisted of 200 healthy, 4-year-old or older oval pomfret females with normal body shape and gonadal development, 200 females (crossbred with *Siniperca brevicornu*), and 200 males. Each group consisted of 100 females and 50 males. After the peak spawning period, the fish were still cultured in Hainan, fed daily with chilled seafood (squid and skipjack tuna in a 1:3 weight ratio) at 4% of their body weight. When using off-season methods to induce maturation, the same dose of hormones was used (i.e., spawning induction). Both females and males were injected with 2 μg of luteinizing hormone-releasing hormone (LH) per kilogram of body weight. 24 hours later, 3 μg of LH was injected again. Spawning occurred 24 hours later, and natural fertilization was observed. Spawn numbers were recorded. Take 200 fertilized eggs and place them in a beaker at 26°C. Perform three parallel tests and calculate the hatching rate and fertilization rate of the fertilized eggs.

[0044] The results showed that the off-season cultivation method could produce effective fertilized eggs, and the total number of eggs laid, fertilization rate and hatching rate were significantly improved, while the traditional method could not produce effective fertilized eggs.

[0045] Table 1

[0046]

[0047] Note: The absence of hormone regulation refers to the absence of fortifiers during the breeding process.

[0048] Example 2

[0049] Fertilized eggs obtained from the female parent (egg-shaped pomfret) and the male parent (egg-shaped pomfret) through off-season breeding were uniformly mixed and then treated using the following two methods.

[0050] Method 1: In the off-season cultivation method of this invention, 6 kg of fertilized eggs are evenly divided into 3 buckets. A 1-ton incubation bucket can handle approximately 2 kg of fertilized eggs. Natural seawater is added to the incubation buckets, followed by 100g of activated carbon with an iodine value of 500 (iodine value can be controlled between 500-1000, and experiments have shown no significant difference in effect) per ton of water to remove ammonia nitrogen and other organic matter and prevent the formation of toxic substances such as chloramine after the addition of disinfectant. Sodium hypochlorite is added at a final concentration of 0.1 ppm to disinfect and soften the eggshells. The incubation temperature is 26℃ (incubation temperatures between 24℃ and 30℃ are acceptable with no significant difference in effect). Salinity is appropriately increased to 36‰ (salinity between 33‰ and 36‰ is acceptable with no significant difference in effect). This accelerates the settling rate of unfertilized or poorly developed eggs. Dead eggs are released approximately one hour after the blastocyst, gastrula, myosarcoma formation, and heartbeat stages to prevent them from affecting other healthy fertilized eggs. The weight of fertilized eggs is recorded four hours after fertilization; each kilogram of fertilized eggs contains 1.1 million eggs. Four hours before hatching, the remaining fertilized eggs are weighed and placed into incubation bags with a water surface area of ​​12 m². 3 1 kg of eggs were placed in each hatching bag. After hatching, 500 mL of water was scooped out of the hatching bag using a beaker, and the amount of fish fry in the beaker was counted. The count was repeated three times and the average was calculated. Based on the ratio of the water in the beaker to the water in the hatching bag, and knowing the number of fish fry in the beaker, the total number of fish fry in the water was calculated. The hatching rate was obtained by dividing the total number of fish fry by the number of fertilized eggs.

[0051] Method Two: The traditional incubation process for fertilized eggs involves dividing 6 kg of fertilized eggs equally into three containers. A one-ton incubation container can handle approximately 2 kg of fertilized eggs. Natural seawater is added to the incubation containers, and the incubation temperature is 26℃ with a salinity of 25‰ (natural seawater salinity). Dead eggs are removed 4 hours and 10 hours after fertilization. Four hours after fertilization, the weight of the fertilized eggs is recorded as the mass of the fertilized eggs; each kilogram of fertilized eggs contains 1.1 million eggs. Four hours before hatching, the weight of the fertilized eggs is measured, and the remaining fertilized eggs are placed in an incubation bag with a water surface area of ​​12 m². 3 1 kg of eggs were placed in each hatching bag. After hatching, 500 mL of water was scooped out of the hatching bag using a beaker, and the amount of fish fry in the beaker was counted. The count was repeated three times and the average was calculated. Based on the ratio of the water in the beaker to the water in the hatching bag, and knowing the number of fish fry in the beaker, the total number of fish fry in the water was calculated. The hatching rate was obtained by dividing the total number of fish fry by the number of fertilized eggs.

[0052] The results showed that the number of eggs remaining during the incubation process of fertilized eggs using this method was significantly higher than that of eggs remaining during the incubation process of traditional fertilized eggs, and the hatching rate of fertilized eggs using this method was also significantly higher than that of eggs produced by the incubation process of traditional fertilized eggs.

[0053] Table 2

[0054]

[0055] Example 3

[0056] Two hundred hybrid pomfret otters and *Brachys brevicornu* were used as the female parent and divided into four groups. One group served as the control group, while the other three groups underwent fin clipping treatment, as follows: Figure 1 Fins were clipped at points 1, 2, and 3 as shown. After clipping, petroleum jelly ointment containing 1% erythromycin was applied to prevent infection. Once the wounds healed, the fish were returned to the raft for normal aquaculture. During breeding, an excessive supply of males was provided to ensure complete fertilization of the females. The number of eggs laid by the females, the average number of eggs laid per fish, the average weight per fish, and the ratio of eggs laid to body weight were recorded and statistically analyzed.

[0057] The results showed that fin clipping of golden pomfret broodstock resulted in better gonadal development, significantly increased egg production, and a higher egg production-to-body weight ratio.

[0058] Table 3

[0059]

[0060] The embodiments described above are only some embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for off-season breeding of golden pomfret, characterized in that, Includes the following steps: (1) Select parent stock for off-season breeding of golden pomfret; (2) The ovaries of the female golden pomfret were all in stage 3 or more mature. After the fish laid eggs in May, they were continuously strengthened. The strengthening was carried out by feeding the female fish with strengthened chilled aquatic products to strengthen the ovaries. The strengthened chilled aquatic products contained a strengthening agent, which contained 5g / L vitamin E, 1g / L vitamin A, 20g / L lecithin, 10g / L bile acid, 20g / L cholesterol, 10g / L Schizochytrium powder, 200g / L glycerol, 1g / L zinc chloride, 5g / L vitamin C, 2g / L arginine, 2g / L lysine, 20g / L monoglyceride and water. (3) In May, female and male fish were injected with human chorionic gonadotropin once. The injection dose for female fish was 800-1000 units / kg, and the injection dose for male fish was 500-600 units / kg to prevent gonadal degeneration. 3-6 days after the injection, the fish were prepared for transportation. Two days before the transportation, the amount of fortified chilled aquatic products fed to the fish was reduced to 0.5%-1% of the fish's body weight. At this time, 100mg of L-carnitine was mixed in every kilogram of chilled aquatic products. The golden pomfret were transported to areas with a latitude higher than 21° and a water temperature lower than 26° to accumulate low temperature for the parent fish. (4) Fin clipping treatment was performed on the parent plants after low-temperature accumulation; (5) Use hormones to regulate the developmental state of the parent gonads, promote gonadal maturation and ovulation; (6) Fertilization is performed to obtain fertilized eggs, which hatch to obtain fish fry; In step (4), the fin trimming method includes the following steps: cutting off 1 / 3 to 1 / 2 of the upper or lower part of the tail fin of the golden pomfret, or cutting off 2 / 3 of the dorsal fin. After trimming the fin, apply petroleum jelly ointment containing erythromycin. After the wound heals, return the fish to the raft for normal aquaculture. In step (5), after being transferred to a region with a latitude higher than 21°, the fish are continuously fed enhanced chilled aquatic products at a rate of 4% of their body weight. Female fish are fed enhanced chilled aquatic products containing 3000-6000 units of follicle-stimulating hormone per kilogram every 5 days, while male fish are fed enhanced chilled aquatic products containing 2000-2500 units of human chorionic gonadotropin per kilogram every 5 days to promote the redevelopment of the gonads. Off-season breeding from August to October is carried out in regions with a latitude higher than 21°, while off-season breeding from October to December is carried out in low-latitude regions. The spawning induction method is as follows: female and male fish are raised together. 2 μg of luteinizing hormone-releasing hormone is injected into both female and male fish per kilogram of body weight. 24 hours later, 3 μg of luteinizing hormone-releasing hormone is injected. Spawning will occur 24 hours later, and fertilization will occur naturally.

2. The method for off-season breeding of golden pomfret according to claim 1, characterized in that, In step (1), the parent species include a female parent and a male parent. The female parent is selected from the oval pomfret or its hybrids. The hybrids include the hybrids of the Brønsted pomfret and the oval pomfret. The male parent includes the oval pomfret.

3. The method for off-season breeding of golden pomfret according to claim 1, characterized in that, In step (1), the parent fish are selected from healthy fish that are 4 years old or older and whose gonads have developed to stage 3 or later.

4. The method for off-season breeding of golden pomfret according to claim 1, characterized in that, In step (2), the preparation method of the enhanced chilled aquatic products is as follows: 100L of fortifier is mixed with 100g of fish meal, and 200g of the mixture is mixed with 10kg of chilled aquatic products; the chilled aquatic products include squid and bonito, and the mass ratio of squid to bonito is 1:3; the feeding amount of the enhanced chilled aquatic products is 2% to 5% of the fish body weight.

5. The method for off-season breeding of golden pomfret according to claim 1, characterized in that, In step (6), the following method is used to improve the fertilization rate: 2-5 kg ​​of fertilized eggs are treated in a 1-ton incubation tank. Natural seawater is added to the incubation tank, followed by 100g of activated carbon with an iodine value of 500-1000 per ton of water, and sodium hypochlorite is added at a final concentration of 0.1ppm. The incubation temperature is 24-30℃ and the salinity is 33-36‰. Dead eggs are released one hour after the end of the blastocyst stage, gastrula stage, myosarcoma formation stage, and heartbeat stage.

Images