Method for on-site rapid artificial insemination of wild pseudosciaena crocea

Abstract

The application provides a method for on-site rapid artificial insemination of wild Pseudosciaena crocea of Lutjanidae, and belongs to the technical field of aquatic animal breeding. Wild parent fish of Pseudosciaena crocea of Lutjanidae are captured in the breeding season; sperm is collected from the selected sexually mature male parent fish on the capture site; after artificial sperm collection, sexually mature female parent fish are selected, and fish eggs are collected; high-quality fertilized eggs are obtained through artificial insemination; the artificial insemination comprises the following steps: adding sperm into fish eggs, adding natural seawater for stirring, and finally washing with natural seawater. Through comprehensive regulation of key links in the whole process of artificial insemination, the purpose of obtaining high-quality fertilized eggs by using wild parent fish of Pseudosciaena crocea of Lutjanidae and carrying out artificial fry breeding is achieved.

Description

Technical Field

[0001] This invention belongs to the field of aquatic animal breeding technology, and in particular relates to a method for rapid on-site artificial insemination of wild large yellow croaker. Background Technology

[0002] Large yellow croaker in my country is generally divided into three groups based on population ecology: the Min-Yue East group (represented by Ningde, Fujian), the Daiqu group (represented by Zhoushan, Zhejiang), and the Naozhou group (mainly found in the nearshore waters of Naozhou, Guangdong). Among these, the Min-Yue East and Daiqu groups have been researched and developed, forming industrial scales in Fujian and Zhejiang. However, the Naozhou group has not yet been developed and utilized. The Naozhou group 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 Min-Yue East and Daiqu groups' poor heat tolerance, preventing their full-scale cultivation in the South China Sea. It is expected to become an important species for future deep-sea aquaculture in the South China Sea.

[0003] During the breeding season, the large yellow croaker (Cetus spp.) migrates in groups to nearshore waters and spawns in fixed spawning grounds. Due to the destruction of spawning grounds and overfishing, the germplasm resources of wild large yellow croaker have shown obvious signs of decline. One key issue to be addressed is to improve the artificial breeding technology of large yellow croaker and obtain high-quality fertilized eggs. There are two main methods to solve this problem: one is to collect wild broodstock with gonads developed to stage IV in shallow waters (8-10 meters deep), control the transportation process, artificially induce spawning, and artificially collect and fertilize eggs to obtain high-quality fertilized eggs. However, the wild broodstock are subject to significant stress during collection and have a short survival time under artificial breeding conditions. The other method is to collect mature wild broodstock with eggs in deep waters (20-40 meters deep) and quickly artificially inseminate them on-site to obtain high-quality fertilized eggs. However, during artificial insemination on-site, the spawning process of parent fish can only be maintained for a short time, the development of testes and ovaries is not synchronized, and the eggs are not mature when they are extracted too early, while they are too mature when they are extracted a little later. As a result, the success rate of fertilization is often low, which seriously restricts the development of artificial breeding of large yellow croaker. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for rapid on-site artificial insemination of wild large yellow croaker from the Naozhou group, thereby improving the fertilization rate.

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

[0006] A method for rapid on-site artificial insemination of wild large yellow croaker (Cyprinus naan) includes the following steps:

[0007] Wild parent fish are captured during the breeding season of the large yellow croaker from Naozhou. Sexually mature male parent fish are selected at the capture site, and their semen is collected for later use. After artificial semen collection, sexually mature female parent fish are selected, and their eggs are collected. Artificial insemination is performed to obtain high-quality fertilized eggs. The artificial insemination includes adding semen to the fish eggs, then adding natural seawater and stirring, and finally rinsing with natural seawater.

[0008] Preferably, wild parent fish are caught in the waters near Naozhou Island, Zhanjiang, Guangdong, at a depth of 20-40m during the neap tides of September and October in the lunar calendar.

[0009] Preferably, after artificial insemination, the fertilized eggs are stirred in natural seawater for 3-4 minutes, then left to stand, and the high-quality fertilized eggs floating on the surface are collected.

[0010] Preferably, the semen is stored at 2-4°C, and the sperm motility rate is 70-80%.

[0011] Preferably, the ratio of semen to fish eggs is 1 mL: 8000-12000 eggs.

[0012] Preferably, the gonads of the wild broodstock of the Naozhou grouper have developed to stage V.

[0013] Preferably, the net retrieval speed when the wild parent fish are captured is 1-2 m / s. If any large yellow croakers are caught in the net during the process, they are placed in a live water tank.

[0014] Preferably, after the artificial insemination is completed, the fertilized eggs are transported back to the land-based aquaculture farm in fish fry plastic bags.

[0015] Preferably, the high-quality fertilized eggs obtained through artificial insemination are incubated in an incubation tank to obtain wild Naozhou large yellow croaker fry.

[0016] Preferably, the incubation conditions are: water temperature 24-26℃, salinity 28-30, pH 8.2-8.5, dissolved oxygen 5.5-6.5 mg / L, and light intensity 800-1100 Lux.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention provides a method for rapid on-site artificial insemination of wild large yellow croaker (Cyprinus naanensis). It comprehensively regulates key stages throughout the entire process, from wild broodstock capture, artificial semen collection, artificial insemination, and collection of high-quality fertilized eggs, effectively improving the fertilization and hatching rates of wild large yellow croaker. This invention, through comprehensive regulation of key stages in the entire artificial insemination process, helps to achieve the goal of obtaining high-quality fertilized eggs from wild large yellow croaker broodstock for artificial seedling breeding. Detailed Implementation

[0019] This invention provides a method for rapid on-site artificial insemination of wild large yellow croaker from Naozhou, comprising the following steps: capturing wild parent fish during the breeding season of large yellow croaker from Naozhou; selecting sexually mature male parent fish at the capture site and collecting semen for later use; after artificial semen collection, selecting sexually mature female parent fish and collecting fish eggs; and performing artificial insemination to obtain high-quality fertilized eggs.

[0020] This invention involves capturing wild broodstock fish in the spawning grounds of the large yellow croaker (Croton tigrinosa) near Naozhou Island, Zhanjiang, Guangdong Province, during the neap tides of September and October in the lunar calendar, in waters with a depth of 20-40 meters, using a single-layer drift gillnet (mesh size approximately 6.5 cm). The net is hauled up at a speed of 1-2 m / s. Based on the large yellow croaker's habit of living in the lower and middle layers of the ocean, this invention controls the net hauling speed to reduce the impact of water pressure stress on the wild broodstock, thus improving their survival rate.

[0021] As an feasible method, when the wild parent fish are captured, the net is set for about 1 hour and then pulled up. If a large yellow croaker is caught in the net during this period, the net is cut with scissors and the large yellow croaker is gently placed into the live water tank and oxygenated to a dissolved oxygen level of 5.0-6.0 mg / L.

[0022] After the wild broodstock are harvested, the present invention involves collecting semen from sexually mature male fish in a live-water tank. The male fish have gonads that have developed to stage V. As one feasible method, the semen collection involves selecting broodstock with no obvious abdominal bulge, wrapping the head with a damp towel, drying the vent with dry gauze, gently pressing the abdomen towards the tail with the thumb to squeeze out the milky white semen, and then using a syringe (5 mL) with the needle removed to draw the semen from the vent.

[0023] The semen described in this invention is stored at 2-4°C. As one feasible method, this invention uses a portable insulated box to store the semen.

[0024] This invention involves diluting a small amount of semen, observing the sperm motility ratio under a microscope, and selecting semen with a sperm motility rate of 70-80% for artificial insemination.

[0025] After artificial insemination, sexually mature female fish with gonads developed to stage V are selected from the live water tank to collect fish eggs. In a specific embodiment of the present invention, female parent fish with swollen abdomen, red genital opening and obvious ovarian outline are selected.

[0026] This invention involves wiping the mucus off the surface of a sexually mature female fish, placing it with its abdomen facing a clean container, and gently squeezing the abdomen to insert the female fish eggs into the container for artificial insemination.

[0027] The artificial insemination method of this invention includes: adding semen to fish eggs and stirring rapidly, wherein the ratio of semen to fish eggs is 1 mL: 8000-12000 eggs, preferably 1 mL: 9000-11000 eggs, and the rapid stirring time is 25-35 seconds, preferably 28-32 seconds, to ensure sufficient contact between the semen and fish eggs; then adding 500 mL of natural seawater that has been filtered and settled and stirring, preferably for 2-3 minutes, to fertilize the fish eggs; finally, rinsing with natural seawater 2-3 times to remove unfertilized semen. The natural seawater used in this invention is natural seawater that has been filtered and settled. In this invention, the natural seawater is allowed to settle for 12 hours, and the upper layer of water is extracted for filtration. The filtration method is a quartz sand filter, purchased from Shijiazhuang Gongquan Water Treatment Technology Co., Ltd.

[0028] After artificial insemination, the fertilized eggs are transferred to a container filled with seawater and temporarily stored with dissolved oxygen at 5.0-6.0 mg / L. Once all artificial insemination is complete, the fertilized eggs are transported back to the land-based aquaculture farm in fish fry plastic bags. These fish fry plastic bags are then filled with pure oxygen to a dissolved oxygen level of 5.0-6.0 mg / L before being packaged and transported back to the land-based aquaculture farm. As a feasible method, thickened double-layered fish fry plastic bags with dimensions of 25*50cm are selected.

[0029] After the fertilized eggs are transported back to the land-based aquaculture farm, they are transferred to incubation tanks for processing. The fertilized eggs are stirred in natural seawater for 3-4 minutes, then left to stand, and the high-quality fertilized eggs floating on the surface are collected.

[0030] In this invention, high-quality fertilized eggs obtained through artificial insemination are incubated in an incubation tank to obtain wild Naozhou large yellow croaker fry. The incubation conditions are: water temperature 24-26℃, salinity 28-30, pH 8.2-8.5, dissolved oxygen 5.5-6.5mg / L, and light intensity 800-1100Lux, preferably water temperature 25℃, salinity 29, pH 8.3, and light intensity 900-1000Lux.

[0031] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0032] Example 1

[0033] Rapid artificial insemination of wild Naozhou croaker in 2023

[0034] Wild broodstock harvesting: During the neap tide in the ninth lunar month, in the spawning grounds of the large yellow croaker (Croatia acutissima) near Naozhou Island, Zhanjiang, Guangdong, in sea areas with a depth of 20-40 meters, deep-water single-layer drift gillnets (net length 40-50m, net height 1.5m, mesh size 6.5cm) are used. The nets are hauled in one hour after being set, with the hauling speed controlled at 1m / s. If broodstock are encountered during the hauling process, the net is immediately cut open, and the broodstock are gently and slowly placed into a live-water tank, which is then oxygenated to a dissolved oxygen level of 5.5mg / L for temporary rearing.

[0035] Artificial semen collection: After the wild broodstock are harvested, sexually mature male fish are selected from the live water tank. Specifically, broodstock with no obvious abdominal bulge are selected. The head is wrapped with a damp towel, the vent is dried with a dry gauze, and the abdomen is gently pressed from the tail to the abdomen to squeeze out the milky white semen. The semen is then drawn from the vent using a syringe (5mL) with the needle removed and placed in a portable incubator (temperature controlled at 3℃). A small amount of semen is diluted and the sperm motility is observed under a microscope. Semen with a sperm motility rate of 70-80% is used for artificial insemination.

[0036] Artificial insemination: After artificial insemination, sexually mature female fish are selected from the live water tank. Specifically, female parent fish with swollen abdomens, red genital openings, and clearly defined ovarian outlines are chosen. The mucus on the surface of the fish is wiped clean with dry gauze. With the abdomen facing the plastic basin, the female fish's eggs are gently squeezed into the clean plastic basin. Then, 1 mL of semen is added for every 10,000 eggs, and the mixture is stirred quickly for 30 seconds to ensure full contact between the sperm and eggs. Immediately afterward, 500 mL of natural seawater that has been filtered and settled is added, and the mixture is stirred for 2 minutes to fertilize the eggs. Finally, the eggs are rinsed twice with natural seawater and transferred to a plastic bucket filled with seawater and oxygenated to a dissolved oxygen level of 5.5 mg / L for temporary storage. After all artificial insemination is completed, the fish are packed in thickened double-layered plastic bags (25*50 cm), filled with pure oxygen to a dissolved oxygen level of 5.5 mg / L, and transported back to the land-based aquaculture farm.

[0037] Collecting high-quality fertilized eggs: The fertilized eggs are transported back to the land-based aquaculture farm and processed in the hatching tanks. The water is gently rotated counterclockwise for 3.5 minutes, and then left to stand for 20 minutes. High-quality fertilized eggs floating on the surface and bad eggs settling at the bottom are collected. The number of floating eggs and the number of settling eggs are recorded, and the fertilization rate is calculated. High-quality fertilized eggs are transferred to a hatching tank with one cubic meter of water for incubation. The incubation conditions are: water temperature 25℃, salinity 28, pH 8.3, dissolved oxygen 5.5mg / L, and light intensity 1000Lux. The hatching rate is calculated after the fry hatch.

[0038] In this embodiment, 100g of fertilized eggs were collected, of which 35.4g were high-quality fertilized eggs, accounting for 35.4%, and the hatching rate of high-quality fertilized eggs was 72.6%.

[0039] Example 2

[0040] Rapid artificial insemination of wild Naozhou croaker in 2024

[0041] Wild broodstock harvesting: During the neap tide in the tenth lunar month, in the spawning grounds of the large yellow croaker (Croatia acutissima) near Naozhou Island, Zhanjiang, Guangdong, in sea areas with a depth of 20-40 meters, deep-water single-layer drift gillnets (net length 40-50m, net height 1.5m, mesh size 6.5cm) are used. The nets are hauled in one hour after being set, with the hauling speed controlled at 1.5m / s. If broodstock are encountered during the hauling process, the net is immediately cut open, and the broodstock are gently and slowly placed into a live-water tank, where dissolved oxygen is increased to 6.0mg / L for temporary rearing.

[0042] Artificial semen collection: After the wild broodstock are harvested, sexually mature male fish are selected from the live water tank. Specifically, broodstock with no obvious abdominal bulge are selected. The head is wrapped with a damp towel, the vent is dried with a dry gauze, and the abdomen is gently pressed from the tail to the abdomen to squeeze out the milky white semen. The semen is drawn from the vent with a syringe (5mL) without the needle and placed in a portable incubator (temperature controlled at 4℃). A small amount of semen is diluted and the sperm motility is observed under a microscope. Semen with a sperm motility rate of 70-80% is used for artificial insemination.

[0043] Artificial insemination: After artificial insemination, sexually mature female fish are selected from the live water tank. Specifically, female parent fish with swollen abdomens, red genital openings, and clearly defined ovarian outlines are chosen. The mucus on the surface of the fish is wiped clean with dry gauze. With the abdomen facing the plastic basin, the female fish's eggs are gently squeezed into the clean plastic basin. Then, 1 mL of semen is added for every 9500 eggs, and the mixture is quickly stirred for 25 seconds to ensure full contact between the sperm and eggs. Immediately afterward, 500 mL of natural seawater that has been filtered and settled is added, and the mixture is stirred for 3 minutes to fertilize the eggs. Finally, the eggs are rinsed 3 times with natural seawater and transferred to a plastic bucket filled with seawater and oxygenated to a dissolved oxygen level of 6.0 mg / L for temporary storage. After all artificial insemination is completed, the fish are packed in thickened double-layered plastic bags (25*50 cm), filled with pure oxygen to a dissolved oxygen level of 6.0 mg / L, and transported back to the land-based aquaculture farm.

[0044] Collecting high-quality fertilized eggs: The fertilized eggs are transported back to the land-based aquaculture farm and processed in the hatching tanks. The water is gently rotated counterclockwise for 4 minutes, and then left to stand for 25 minutes. High-quality fertilized eggs floating on the surface and bad eggs settling at the bottom are collected. The number of floating eggs and the number of settling eggs are recorded, and the fertilization rate is calculated. High-quality fertilized eggs are transferred to a hatching tank with one cubic meter of water for incubation. The incubation conditions are: water temperature 26℃, salinity 29, pH 8.4, dissolved oxygen 6.5mg / L, and light intensity 800Lux. The hatching rate is calculated after the fry hatch.

[0045] In this embodiment, 284g of fertilized eggs were collected, of which 120.7g were high-quality fertilized eggs, accounting for 42.5%, and the hatching rate of high-quality fertilized eggs was 76.4%.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for rapid on-site artificial insemination of wild large yellow croaker (Cyprinus naanensis), characterized in that, Includes the following steps: Wild parent fish are captured during the breeding season of the large yellow croaker from Naozhou. Sexually mature male parent fish are selected at the capture site, and their semen is collected for later use. After artificial semen collection, sexually mature female parent fish are selected, and their eggs are collected. Artificial insemination was performed to obtain high-quality fertilized eggs; Wild broodstock of the Naozhou grouper have reached stage V in gonad development; The artificial insemination process includes: adding semen to fish eggs and stirring rapidly, wherein the ratio of semen to fish eggs is 1 mL: 8000-12000 eggs, and the rapid stirring time is 25-35 s to ensure that the semen and fish eggs are in full contact; then adding 500 mL of natural seawater that has been filtered and settled and stirring for 2-3 minutes to fertilize the fish eggs; finally rinsing with natural seawater 2-3 times to remove unfertilized semen. After artificial insemination is completed, the fertilized eggs are stirred in natural seawater for 3-4 minutes, then left to stand, and the high-quality fertilized eggs floating on the surface are collected.

2. The method according to claim 1, characterized in that, Wild parent fish were caught in the waters near Naozhou Island in Zhanjiang, Guangdong, during the neap tides in September and October of the lunar calendar, at depths of 20-40 meters.

3. The method according to claim 1, characterized in that, The semen was stored at 2-4℃, and the sperm motility rate was 70-80%.

4. The method according to claim 1, characterized in that, The net was hauled up at a speed of 1-2 m / s when the wild parent fish were captured. During the process, a large yellow croaker from the Naozhou group was caught in the net and placed in a live water tank.

5. The method according to claim 1, characterized in that, After artificial insemination is completed, the fertilized eggs are transported back to the land-based aquaculture farm in fish fry plastic bags.

6. The method according to claim 1, characterized in that, The high-quality fertilized eggs obtained through artificial insemination are incubated in an incubation tank to obtain wild Naozhou large yellow croaker fry.

7. The method according to claim 6, characterized in that, The incubation conditions are as follows: water temperature 24-26℃, salinity 28-30, pH 8.2-8.5, dissolved oxygen 5.5-6.5 mg / L, and light intensity 800-1100 Lux.