Method for obtaining high-quality fertilized eggs of wild sal-family large yellow croakers

Abstract

The invention discloses a method for obtaining high-quality fertilized eggs of wild sal-family pseudosciaena crocea, and belongs to the technical field of aquatic animal breeding. The method comprises the following steps: capturing wild parent fishes in the breeding season of the sal-family pseudosciaena crocea and transporting the wild parent fishes to a farm; the method comprises the following steps: carrying out temporary culture and intensive culture on wild parent fishes, selecting male and female wild parent fishes with mature gonads, anesthetizing, and injecting artificial spawning induction mixed hormones; after artificial spawning mixed hormones are injected, ova and seminal fluid are collected, and high-quality fertilized ova are obtained through artificial insemination. According to the method, all the technical steps are associated with one another to form a whole, the high-quality fertilized eggs of the large yellow croakers of the wild sal ammoniac family can be successfully obtained, and the proportion of the obtained high-quality fertilized eggs reaches 45% or above. According to the method, the obtained high-quality fertilized eggs are adopted for fry hatching, the hatching rate of the obtained fertilized eggs reaches 62% or above, the fertilized eggs can be used for constructing and breeding a wild sal-family pseudosciaena crocea basic population, and artificial breeding of the sal-family pseudosciaena crocea is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of aquatic animal cultivation and breeding, and in particular to a method for obtaining high-quality fertilized eggs of wild Naozhou large yellow croaker. Background Art

[0002] According to the population ecology, my country's yellow croaker is generally divided into three groups, namely the Fujian-Yuedong group represented by Ningde, Fujian, the Daiqu group represented by Zhoushan, Zhejiang, and the Naozhou group mainly in the coastal waters of Naozhou, Guangdong. The three groups of yellow croaker differ in terms of sexual maturity age, population age composition, and stress resistance. Due to the different biological characteristics and biological learning abilities of each species, different methods should be adopted in the field of artificial cultivation and breeding technology. At present, the Fujian-Yuedong and Daiqu groups have made breakthroughs in artificial breeding technology and achieved a certain scale of seedling cultivation, while the artificial breeding of the Naozhou group of yellow croaker has not yet been fully developed.

[0003] The Naozhou large yellow croaker has a unique advantage in adapting to the high sea conditions of deep-sea aquaculture. This characteristic makes it a more advantageous variety in the development of deep-sea aquaculture in Guangdong. After large-scale aquaculture, it will effectively solve the industrial development bottleneck that the Fujian Min-Yuedong large yellow croaker and the Zhejiang Daiqu large yellow croaker have poor high temperature resistance and cannot be fully aquacultured in the South China Sea. It is expected to become an important development variety for deep-sea aquaculture in the South China Sea in the future. Breaking through the artificial breeding technology of the Naozhou large yellow croaker and obtaining high-quality fertilized eggs is one of the key issues to be solved. Because wild Naozhou large yellow croakers live in the middle and lower layers of the nearshore, the capture process is more stressful, and the survival time is short under artificial breeding conditions, making it difficult to construct a basic broodstock population for artificial breeding. Therefore, in the current existing artificial breeding methods of Naozhou large yellow croaker, parents with good gonad maturity are usually captured during the breeding season for artificial egg collection and artificial insemination. However, the spawning process of the parent fish in this method can only be maintained for a short time, the testis and ovary develop asynchronously, the eggs squeezed out too early are immature, and the eggs squeezed out a little later are overmature, often resulting in a low success rate of fertilization. Therefore, obtaining high-quality fertilized eggs from wild Naozhou large yellow croaker has become the first problem to be solved in its artificial breeding technology. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a method for obtaining high-quality fertilized eggs of wild Naozhou large yellow croaker, and the proportion of the obtained high-quality fertilized eggs is more than 45%.

[0005] The present invention also aims to provide a method for obtaining wild Naozhou large yellow croaker fry, by using the high-quality fertilized eggs of the present invention for hatching, the hatching rate obtained is above 62%.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for obtaining high-quality fertilized eggs of wild Naozhou large yellow croaker, comprising the following steps:

[0008] Wild broodstock are captured during the breeding season of the Naozhou giant yellow croaker; the wild broodstock are placed in live water tanks and transported back to the harbor and then transported to the breeding farm; the wild broodstock are temporarily raised for 3 to 5 days and then subjected to intensive culture for 8 to 10 days, male and female wild broodstock with mature gonads are selected, anesthetized with eugenol and injected with artificial oxytocin mixed hormones; 22 to 26 hours after the injection of the artificial oxytocin mixed hormones, the eggs and semen are collected, and artificial insemination is performed to obtain high-quality fertilized eggs.

[0009] Preferably, the wild broodstock are captured by setting trap nets in the spawning grounds of the Naozhou large yellow croaker.

[0010] Preferably, the dissolved oxygen in the active water tank is 5 to 5.5 mg / L.

[0011] Preferably, during the transportation to the breeding farm, the water temperature is 22-24° C. and the dissolved oxygen is 6-6.5 mg / L.

[0012] Preferably, the conditions for temporary rearing and intensive culture of the wild broodstock are: water temperature 22-24°C, salinity 28-30, pH 8.0-8.5, light intensity 500-800 lux, dissolved oxygen 5-6 mg / L, ammonia nitrogen ≤0.1 mg / L, and water flow rate 15-25 cm / s.

[0013] Preferably, the wild broodstock are not fed during the temporary rearing stage, and live dicynogloeospermum are released at 8:00 and 14:00 every day during the intensive culture stage, with the release amount being 10-20% of the broodstock body weight.

[0014] Preferably, the mass concentration of the eugenol is 18-22 mg / L, and the anesthesia time is 8-12 min; the artificial oxytocin mixed hormone consists of 1800-2200 IU / mL of chorionic gonadotropin, 290-310 μg / mL of luteinizing hormone releasing hormone analogue No. 2, and 14-16 mg / mL of dioestrogen maleate, the injection dose for female fish is 1.8-2.2 mL / kg, and the injection dose for male fish is halved.

[0015] Preferably, the method for obtaining high-quality fertilized eggs through artificial insemination is as follows: in a dry container, 8,000 to 12,000 eggs are fully contacted per milliliter of semen for 25 to 35 seconds, then 10 to 15 mL of natural seawater is added, stirred for 1 to 2 minutes, and then 300 to 400 mL of natural seawater that has been filtered through sedimentation is added and allowed to stand for 15 to 20 minutes. After rinsing with natural seawater 1 to 2 times, the mixture is allowed to stand for another 18 to 25 minutes, and the fertilized eggs floating on the water surface are collected.

[0016] The present invention also provides a method for obtaining wild Naozhou giant yellow croaker fry, comprising the following steps: obtaining high-quality fertilized eggs of wild Naozhou giant yellow croaker according to the above method for obtaining high-quality fertilized eggs of wild Naozhou giant yellow croaker, hatching the fertilized eggs, and obtaining wild Naozhou giant yellow croaker fry.

[0017] Preferably, the incubation conditions are: water temperature 22-24° C., salinity 28-30, pH 8.0-8.5, dissolved oxygen 5-6 mg / L, light intensity 500-800 lux, and incubation time 24-26 h.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0019] The present invention carries out comprehensive regulation of key links in the whole process from the steps of wild broodstock capture, transportation process control, broodstock temporary rearing and intensive cultivation, artificial induction of labor, artificial egg collection and fertilization, fertilized egg collection and separation, etc. The various technical steps are interconnected to form a whole, and high-quality fertilized eggs of wild Naozhou large yellow croaker can be successfully obtained. The proportion of the high-quality fertilized eggs is more than 45%, and the hatching rate of the obtained fertilized eggs is more than 62%. The fertilized eggs can be used to construct a basic population for breeding wild Naozhou large yellow croaker, and provide high-quality fry for the artificial breeding of Naozhou large yellow croaker. DETAILED DESCRIPTION

[0020] The invention provides a method for obtaining high-quality fertilized eggs of wild Naozhou large yellow croaker, comprising the following steps: capturing wild broodstock in the breeding season of Naozhou large yellow croaker; placing the wild broodstock in a live water tank and transporting them back to a harbor, and then transporting them to a breeding farm; temporarily culturing the wild broodstock for 3 to 5 days and then conducting intensive culture for 8 to 10 days, selecting male and female wild broodstock with mature gonads, anesthetizing them with eugenol and injecting artificial oxytocin mixed hormones; 22 to 26 hours after the injection of the artificial oxytocin mixed hormones, collecting eggs and semen, and conducting artificial insemination to obtain high-quality fertilized eggs.

[0021] The present invention captures wild broodstock by setting a trap net near the spawning ground of Naozhou croaker during the breeding season of Naozhou croaker. The trap net is preferably a special catching net for Naozhou croaker, which is composed of a net wall, a net body and a net bag, with a total length of 140 meters, a total width of 140 meters, a total height of 5 meters, a net wall mesh of 5 cm, and a net body mesh of 10 cm. This method can avoid the problem of short survival time of wild broodstock caused by greater stress during the catching process, and can improve the survival rate of wild broodstock.

[0022] The Naozhou large yellow croaker has a reproductive migratory habit, and the Cunliang Bay of Naozhou (20 degrees 52 minutes north latitude, 110 degrees 36 minutes east longitude) is its spawning ground. The capture location of the Naozhou large yellow croaker described in the present invention is preferably near the Cunliang Bay of Naozhou.

[0023] The present invention places the captured wild broodstock into a live water tank and transports them back to the harbor, and then transports them to a breeding farm. The dissolved oxygen in the live water tank is 5 to 5.5 mg / L, and during the transportation to the breeding farm, the water temperature is 22 to 24° C., and the dissolved oxygen is 6 to 6.5 mg / L. The present invention uses pure oxygen to oxygenate the water body during transportation, and by controlling the dissolved oxygen content and water temperature in the water, the death of the newly captured wild broodstock due to excessive stimulation by external factors can be avoided, which is beneficial to improving the survival rate of the wild broodstock.

[0024] After the wild broodstock of the present invention arrives at the breeding farm, it is preferred to treat the damaged parts of the fish body by applying erythromycin ointment to kill pathogens, promote wound healing, and avoid the death of the broodstock. As an optional embodiment, after the wild broodstock arrives at the breeding farm, the fish are slowly scooped up with a hand net and put into a plastic bucket filled with half a bucket of water, and then the fish eyes are wrapped with a wet towel, and the damaged parts of the fish body are applied with erythromycin ointment, and then slowly transferred to an indoor cement pool (5m long×4m wide×1.5m high).

[0025] The present invention temporarily raises the treated wild broodstock in oxygenated micro-flow water for 3 to 5 days, preferably 4 days; and then strengthens the broodstock for 8 to 10 days, preferably 9 days. The conditions for temporary raising and strengthening the wild broodstock of the present invention are: water temperature 22 to 24°C, salinity 28 to 30, pH value 8.0 to 8.5, light intensity 500 to 800 lux, dissolved oxygen 5 to 6 mg / L, ammonia nitrogen ≤ 0.1 mg / L, and water flow rate 15 to 25 cm / s. The water temperature is preferably 23°C; the salinity is preferably 29; the light intensity is preferably 600 to 700 lux; the water flow rate is preselected to be 20 to 22 cm / s. Increased ammonia nitrogen concentration can easily lead to poisoning of the large yellow croaker of the Naozhou tribe, affecting its growth and development, respiratory metabolism and immune function. Excessively high ammonia nitrogen concentration may cause a large number of deaths of large yellow croaker of the Naozhou tribe. The present invention sets ammonia nitrogen to ≤0.1 mg / L, which will not cause a stress response in the Naozhou large yellow croaker, thereby avoiding the influence on the growth and gonad development of the Naozhou large yellow croaker.

[0026] The wild broodstock of the present invention are not fed during the temporary rearing stage, and live dicynogloeospermum are released at 8:00 and 14:00 every day during the intensive culture stage, and the release amount is 10-20% of the broodstock body weight, preferably 12-18%, more preferably 14-16%, and most preferably 15%. The present invention can reduce the stress of broodstock by temporarily rearing the broodstock, and can promote the gonadal development of the broodstock, improve the quality of eggs, and promote the ovulation of the broodstock after the gonads mature through intensive culture of the broodstock, so as to increase the proportion of high-quality fertilized eggs. The water flow velocity is an important environmental factor affecting the gonadal development of the Naozhou large yellow croaker. The Naozhou large yellow croaker can obtain spawning signals according to the flow velocity of the water flow. The present invention can effectively stimulate the Naozhou large yellow croaker to spawn by setting the water flow velocity.

[0027] The invention selects male and female broodstock with mature gonads after intensive broodstock culture, and injects artificial oxytocin mixed hormone after eugenol anesthesia; the mass concentration of eugenol is 18-22 mg / L, and the anesthesia time is 8-12 min; the mass concentration of eugenol is preferably 20 mg / L; the anesthesia time is preferably 10 min; the artificial oxytocin mixed hormone consists of 1800-2200 IU / mL of chorionic gonadotropin, 290-310 μg / mL of luteinizing hormone releasing hormone analogue No. 2 and 14-16 mg / mL of dioconazole maleate; preferably, the artificial oxytocin mixed hormone consists of 1900-2000 IU / mL of chorionic gonadotropin, 300 μg / mL of luteinizing hormone releasing hormone analogue No. 2 and 15 mg / mL of dioconazole maleate; the injection dose of female fish is 1.8-2.2 mL / kg, preferably 2 mL / kg; the injection dose of male fish is halved compared with that of female fish.

[0028] The present invention places the broodstock after injection of induced spawning in the same indoor cement pool, so that the female broodstock and the male broodstock are fully in contact, and the sexual signals released by the male fish in the water body are used to promote the sexual maturity of the female fish. The broodstock breeding conditions of the present invention are: water temperature 22-24°C, salinity 28-30, pH value 8.0-8.5, light intensity 500-800lux, dissolved oxygen 5-6mg / L, ammonia nitrogen ≤0.1mg / L, and water flow rate 15-25cm / s. The water temperature is preferably 23°C; the salinity is preferably 29; the light intensity is preferably 600-700lux; and the water flow rate is pre-selected to be 20-22cm / s.

[0029] The spawning process of wild broodstock in the natural environment is uncontrollable, and the testis and ovary develop asynchronously. The present invention can induce the gonadal development of male and female broodstock to stage V at the same time by selecting artificial induced ovulation mixed hormone components, controlling the injection amount of artificial induced ovulation mixed hormones and the broodstock breeding conditions after injection of induced ovulation, thus overcoming the problem of asynchronous gonadal development of wild broodstock and effectively improving the fertilization rate and fertilized egg quality.

[0030] The present invention collects eggs and semen 22 to 26 hours after the injection of artificial oxytocin mixed hormone, preferably 24 to 25 hours after the injection. As an optional embodiment, the present invention gently presses the male fish, squeezes the testis, collects semen at the cloaca with a rubber-tipped dropper, and puts it into a dried container. The female fish body is wiped dry with a dry towel, and the eggs are squeezed into the dried container.

[0031] The present invention uses the collected eggs and semen for artificial insemination to obtain high-quality fertilized eggs. The method for obtaining high-quality fertilized eggs through artificial insemination is as follows: in a dry container, 8,000 to 12,000 eggs per milliliter of semen are fully contacted for 25 to 35 seconds, and then 10 to 15 mL of natural seawater after sand filtration is added, stirred for 1 to 2 minutes, and then 300 to 400 mL of natural seawater is added and allowed to stand for 15 to 20 minutes. After rinsing with natural seawater 1 to 2 times, it is allowed to stand again for 18 to 25 minutes, and the fertilized eggs floating on the water surface are collected. The ratio of semen to eggs is preferably 1 mL: 9,000 to 11,000 eggs, and more preferably 1 mL: 10,000 eggs; the quick contact time of semen and eggs is preferably 28 to 32 seconds, and more preferably 30 seconds.

[0032] The present invention also provides a method for obtaining wild Naozhou large yellow croaker fry, comprising the following steps: obtaining high-quality fertilized eggs of wild Naozhou large yellow croaker according to the above method, hatching the fertilized eggs, and obtaining wild Naozhou large yellow croaker fry.

[0033] The incubation conditions of the present invention are: water temperature 22-24°C, salinity 28-30, pH 8.0-8.5, dissolved oxygen 5-6 mg / L, light intensity 500-800 lux, and incubation time 24-26 hours. The water temperature is preferably 23°C, the salinity is preferably 29, the dissolved oxygen is preferably 5.5 mg / L, the light intensity is preferably 600-700 lux, and the incubation time is preferably 25 hours.

[0034] Dissolved oxygen in water is one of the important environmental factors for breeding of large yellow croaker broodstock. Too low or too high dissolved oxygen concentration will cause a certain degree of damage to the physiological metabolism, behavioral activities and reproductive development of large yellow croaker. The present invention accurately controls the dissolved oxygen content in water according to the physiological needs of large yellow croaker in the stages of capture, transportation, temporary breeding, intensive cultivation and hatching, and sets the corresponding dissolved oxygen content, thereby effectively improving the survival rate and high-quality fertilized egg ratio of large yellow croaker.

[0035] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In a specific embodiment of the present invention, eugenol was purchased from Ji'an Borui Spice Oil Co., Ltd.; human chorionic gonadotropin, luteinizing hormone releasing hormone analogue No. 2, and dioxin maleate were all purchased from Ningbo Second Hormone Factory.

[0037] Example 1

[0038] Obtain high-quality fertilized eggs from wild Naozhou croaker during the 2023 Naozhou croaker breeding season:

[0039] (1) Capturing wild broodstock: During the breeding season of the large yellow croaker of the Naozhou tribe, wild broodstock are captured by setting up trap nets in the sea area of ​​8 to 10 m water depth near Cunliang Bay, Naozhou (20 degrees 52 minutes north latitude, 110 degrees 36 minutes east longitude). The trap net is composed of a net wall, a net body and a net bag, with a total length of 140 meters, a total width of 140 meters, a total height of 5 meters, a net wall mesh of 5 cm, and a net body mesh of 10 cm. Two days after the net is set, the broodstock are collected in the net bag at 4 to 5 o'clock in the morning, and the broodstock are slowly picked up with a hand net and placed in the live water tank of the speedboat. The live water tank is oxygenated to 5 mg / L and then transported back to the harbor.

[0040] (2) Transport back to the farm: After the broodstock are transported back to the harbor, the large yellow croakers are slowly transferred to a special live fish transport vehicle with water in a plastic bucket. The live fish transport vehicle uses pure oxygen to increase the oxygen to 6 mg / L, and ice bars are used to cool the compartment. The water temperature is controlled at 23°C during transportation. After arriving at the farm, the fish are slowly scooped up with a hand net and placed in a plastic bucket filled with half a bucket of water. Then the fish eyes are wrapped with a wet towel, and the damaged parts of the fish body are smeared with erythromycin ointment, and then slowly transferred to an indoor cement pool (5m long × 4m wide × 1.5m high).

[0041] (3) Broodstock temporary rearing and intensive culture: In cement ponds, water temperature is 23℃, salinity is 29, pH is 8.5, light intensity is 700lux, dissolved oxygen is 5.5mg / L, ammonia nitrogen is ≤0.1mg / L, and water flow rate is 20cm / s. Broodstock are temporarily reared for 4 days without feeding; intensive culture is carried out for 10 days, and live dicynoglossum worms weighing 15% of the broodstock body weight are released at 8:00 and 14:00 every day during the intensive culture period.

[0042] (4) Injection of oxytocin: Select male and female Naozhou croakers with mature gonads, with a body weight of more than 600 g for males and more than 800 g for females, 5 for each sex, anesthetize with eugenol (eugenol concentration is 20 mg / L) for 10 min, and inject a mixed artificial oxytocin hormone (2000 IU / mL of chorionic gonadotropin, 300 μg / mL of luteinizing hormone-releasing hormone analogue No. 2, and 15 mg / mL of dioxygenase maleate) into the thoracic cavity of the broodstock at one time. The injection dose is 2 mL per 1000 g of female fish and 1 mL per 1000 g of male fish. The injected Naozhou croakers were placed in the same indoor cement pool. The water temperature in the cement pool was 23°C, the salinity was 29, the pH was 8.5, the light intensity was 700 lux, the dissolved oxygen was 5.5 mg / L, the ammonia nitrogen was ≤0.1 mg / L, and the water flow rate was 20 cm / s.

[0043] (5) Artificial insemination: 24 hours after the injection of mixed oxytocin, the male fish was gently held down, the testes were squeezed, and the semen was collected at the cloaca with a rubber-tipped dropper and placed in a dried beaker. The female fish body was wiped dry with a dry towel, and the eggs were squeezed into a dried plastic basin. Then 1 mL of semen was added for 10,000 eggs, and the sperm and eggs were allowed to fully contact for 30 seconds. Then 13 mL of natural seawater filtered through sand was added to activate the fertilized eggs. After stirring for 1.5 minutes, 400 mL of natural seawater was added, and the mixture was allowed to stand for 18 minutes. The mixture was rinsed twice with natural seawater and transferred to a 2L measuring cylinder.

[0044] (6) Collection of high-quality fertilized eggs: Since fertilized eggs are floating eggs, after standing in the fertilized egg measuring cylinder for 20 minutes, the eggs floating on the water surface are high-quality fertilized eggs, and the eggs sinking to the bottom are bad fertilized eggs. Record the number of floating eggs and the number of precipitated eggs, and calculate the fertilization rate.

[0045] In this embodiment, after the wild broodstock are captured in step (1), the survival rate of the captured wild broodstock is 73%; after the transportation in step (2), the survival rate of the wild broodstock transported back to the farm is 85%; after the temporary rearing and intensive cultivation of the broodstock in step (3), the survival rate of the broodstock is 72%; and after anesthesia and injection of oxytocin in step (4), the survival rate of the broodstock is 100%. In this embodiment, the fertilization rate is 45.2%, and a total of 115g of fertilized eggs are collected, of which 52g are high-quality fertilized eggs, accounting for 45.22%.

[0046] Example 2

[0047] Obtain high-quality fertilized eggs from wild Naozhou croaker during the 2024 Naozhou croaker breeding season:

[0048] (1) Capturing wild broodstock: During the breeding season of the large yellow croaker of the Naozhou tribe, wild broodstock were captured by setting up trap nets in the sea area of ​​8 to 10 m water depth near Cunliang Bay, Naozhou (20 degrees 52 minutes north latitude, 110 degrees 36 minutes east longitude). The trap net is composed of a net wall, a net body and a net bag, with a total length of 140 meters, a total width of 140 meters, a total height of 5 meters, a net wall mesh of 5 cm, and a net body mesh of 10 cm. Three days after the net is set, the broodstock are collected from the net bag at 4 to 5 o'clock in the morning, and the broodstock are slowly picked up with a hand net and placed in the live water tank of the speedboat. The live water tank is oxygenated to 5.5 mg / L and then transported back to the harbor.

[0049] (2) Transport back to the farm: After the broodstock are transported back to the harbor, the large yellow croakers are slowly transferred to a special live fish transport vehicle with water in a plastic bucket. The live fish transport vehicle uses pure oxygen to increase the oxygen concentration to 6.5 mg / L, and ice bars are used to cool the compartment. The water temperature is controlled at 24°C during transportation. After arriving at the farm, the fish are slowly scooped up with a hand net and placed in a plastic bucket filled with half a bucket of water. Then the fish eyes are wrapped with a wet towel, and the damaged parts of the fish body are smeared with erythromycin ointment, and then slowly transferred to an indoor cement pool (5m long × 4m wide × 1.5m high).

[0050] (3) Temporary rearing and intensive culture of broodstock: In cement ponds, water temperature is 24°C, salinity is 28, pH is 8.4, light intensity is 600 lux, dissolved oxygen is 5 mg / L, ammonia nitrogen is ≤ 0.1 mg / L, and water flow rate is 20 cm / s. The broodstock are temporarily reared for 3 days, and no feeding is given during the temporary rearing stage; the intensive culture is carried out for 9 days, and live dicynoglossum worms weighing 20% ​​of the broodstock body weight are released at 8:00 and 14:00 every day during the intensive culture stage.

[0051] (4) Injection of oxytocin: Select male and female Naozhou croakers with mature gonads, with a body weight of more than 600 g for males and more than 800 g for females, 5 for each sex, anesthetize with eugenol (eugenol concentration is 20 mg / L) for 10 min, and inject a mixed artificial oxytocin hormone (2000 IU / mL of chorionic gonadotropin, 300 μg / mL of luteinizing hormone-releasing hormone analogue No. 2, and 15 mg / mL of dioxygenase maleate) into the thoracic cavity of the broodstock at one time. The injection dose is 2 mL per 1000 g of female fish and 1 mL per 1000 g of male fish. The injected Naozhou croakers were placed in the same indoor cement pool. The water temperature in the cement pool was 24°C, the salinity was 28, the pH was 8.3, the light intensity was 600 lux, the dissolved oxygen was 5 mg / L, the ammonia nitrogen was ≤0.1 mg / L, and the water flow rate was 20 cm / s.

[0052] (5) Artificial insemination: 24 hours after the injection of mixed oxytocin, the male fish was gently held down, the testes were squeezed, and the semen was collected at the cloaca with a rubber-tipped dropper and placed in a dried beaker. The female fish body was wiped dry with a dry towel, and the eggs were squeezed into a dried plastic basin. Then 1 mL of semen was added for 10,000 eggs, and the sperm and eggs were allowed to fully contact for 30 seconds. Then 15 mL of natural seawater filtered through sand was added to activate the fertilized eggs. After stirring for 2 minutes, 350 mL of natural seawater was added, and the mixture was allowed to stand for 20 minutes. The mixture was rinsed twice with natural seawater and transferred to a 2L measuring cylinder.

[0053] (6) Collection of high-quality fertilized eggs: Since fertilized eggs are floating eggs, after standing in the fertilized egg measuring cylinder for 20 minutes, the eggs floating on the water surface are high-quality fertilized eggs, and the eggs sinking to the bottom are bad fertilized eggs. Record the number of floating eggs and the number of precipitated eggs, and calculate the fertilization rate.

[0054] In this embodiment, after the wild broodstock are captured in step (1), the survival rate of the captured wild broodstock is 68%; after the transportation in step (2), the survival rate of the wild broodstock transported back to the farm is 78%; after the temporary rearing and intensive cultivation of the broodstock in step (3), the survival rate of the broodstock is 65%; and after anesthesia and injection of oxytocin in step (4), the survival rate of the broodstock is 100%. In this embodiment, the fertilization rate is 64%, and a total of 86g of fertilized eggs are collected, of which 41g are high-quality fertilized eggs, and the proportion of high-quality fertilized eggs reaches 47.67%.

[0055] Example 3

[0056] Obtain wild Naozhou giant yellow croaker fry in 2023:

[0057] Steps (1) to (6) are the same as in Example 1.

[0058] (7) Incubation of fertilized eggs: high-quality fertilized eggs are transferred to an incubation bucket with one cubic meter of water for incubation. The incubation conditions are: water temperature 23°C, salinity 29, pH 8.5, dissolved oxygen 5.5 mg / L, light intensity 600 lux, and incubation time 25 hours. The hatching rate is calculated after the fry have hatched.

[0059] The hatching rate in this embodiment is 62.7%.

[0060] Example 4

[0061] Obtain wild Naozhou giant yellow croaker fry in 2024:

[0062] Steps (1) to (6) are the same as those in Example 2.

[0063] (7) Incubation of fertilized eggs: high-quality fertilized eggs are transferred to an incubation bucket with one cubic meter of water for incubation. The incubation conditions are: water temperature 24°C, salinity 30, pH 8.3, dissolved oxygen 5.5 mg / L, light intensity 700 lux, and incubation time 25 hours. The hatching rate is calculated after the fry have hatched.

[0064] The hatchability in this embodiment is 65.8%.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for obtaining high-quality fertilized eggs of wild large yellow croaker of the Naozhou tribe, characterized in that: The following steps are involved: Wild broodstock are captured during the breeding season of the Naozhou giant yellow croaker; the wild broodstock are placed in live water tanks and transported back to the harbor and then transported to the breeding farm; the wild broodstock are temporarily raised for 3 to 5 days and then subjected to intensive culture for 8 to 10 days, male and female wild broodstock with mature gonads are selected, anesthetized with eugenol and injected with artificial oxytocin mixed hormones; 22 to 26 hours after the injection of the artificial oxytocin mixed hormones, the eggs and semen are collected, and artificial insemination is performed to obtain high-quality fertilized eggs.

2. The method according to claim 1, characterized in that The wild broodstock are captured by setting trap nets in the spawning grounds of the Naozhou large yellow croaker.

3. The method according to claim 1, characterized in that The dissolved oxygen in the live water tank is 5-5.5 mg / L.

4. The method according to claim 1, characterized in that: During the transportation to the breeding farm, the water temperature is 22-24° C. and the dissolved oxygen is 6-6.5 mg / L.

5. The method according to claim 1, characterized in that The conditions for temporary rearing and intensive cultivation of the wild broodstock are: water temperature 22-24°C, salinity 28-30, pH value 8.0-8.5, light intensity 500-800 lux, dissolved oxygen 5-6 mg / L, ammonia nitrogen ≤0.1 mg / L, and water flow rate 15-25 cm / s.

6. The method according to claim 1, characterized in that Wild broodstock are not fed during the temporary rearing stage. During the intensive cultivation stage, live dicynomolgus are released at 8:00 and 14:00 every day, and the release amount is 10-20% of the broodstock body weight.

7. The method according to claim 1, characterized in that The mass concentration of the eugenol is 18-22 mg / L, and the anesthesia time is 8-12 min; the artificial oxytocin mixed hormone consists of 1800-2200 IU / mL of chorionic gonadotropin, 290-310 μg / mL of luteinizing hormone releasing hormone analogue No. 2, and 14-16 mg / mL of dioestrogen maleate; the injection dose for female fish is 1.8-2.2 mL / kg, and the injection dose for male fish is halved.

8. The method according to claim 1, characterized in that The method for obtaining high-quality fertilized eggs through artificial insemination is as follows: in a dry container, 8,000 to 12,000 eggs per milliliter of semen are fully contacted for 25 to 35 seconds, then 10 to 15 mL of natural seawater is added, stirred for 1 to 2 minutes, and then 300 to 400 mL of natural seawater filtered by sedimentation is added and allowed to stand for 15 to 20 minutes. After rinsing with natural seawater 1 to 2 times, it is allowed to stand again for 18 to 25 minutes, and the fertilized eggs floating on the water surface are collected.

9. A method for obtaining wild Naozhou large yellow croaker fry, characterized in that: The method comprises the following steps: obtaining high-quality fertilized eggs of wild Naozhou large yellow croaker according to the method described in any one of claims 1 to 8, and hatching the fertilized eggs to obtain wild Naozhou large yellow croaker fry.

10. The method according to claim 9, characterized in that: The incubation conditions are: water temperature 22-24° C., salinity 28-30, pH value 8.0-8.5, dissolved oxygen 5-6 mg / L, light intensity 500-800 lux, and incubation time 24-26 hours.