Methods for regulating the natural spawning of broodstock of leopard gills in industrialized indoor environments

Abstract

This invention discloses a method for regulating the natural spawning of leopard-gill sea bass broodstock in an indoor, factory-scale facility, relating to the field of leopard-gill sea bass breeding technology. The invention includes broodstock selection, broodstock rearing, and reproductive regulation of natural spawning. Reproductive regulation of natural spawning refers to controlling conditions such as water temperature, photoperiod, and nutritional enhancement during broodstock rearing to synchronize gonadal development and ultimately induce natural spawning, obtaining a large quantity of high-quality fertilized eggs. This invention can induce broodstock to spawn naturally in indoor rearing ponds within a 45-50 day regulation period, with a spawning period of up to 174 days, achieving a fertilization rate of over 95% and a hatching rate of over 80%. This invention represents a breakthrough in the factory-scale indoor natural spawning of leopard-gill sea bass, effectively promoting the large-scale breeding of leopard-gill sea bass fry and the development of the seed industry.

Description

Technical Field

[0001] This invention relates to the field of leopard gill sea bass breeding technology, specifically to a method for regulating the natural spawning of leopard gill sea bass broodstock in a factory setting. Background Technology

[0002] Leopard sea bass (Plectropomus leopardus) belongs to the order Perciformes, family Serranidae, and genus Plectropomus. It is commonly known as the "Eastern Star Sea Bass" due to its elongated body and vibrant colors, covered in star-like spots. It prefers to inhabit warm coral reef areas in tropical and subtropical regions, and is adept at ambushing other fish under the cover of coral reefs. Wild leopard sea bass are mainly distributed in the western Pacific Ocean, including northern Australia, southern Japan, and southern China, with the widest distribution in my country, particularly in the South China Sea and the Taiwan Strait. It is a large carnivorous fish with strong swimming ability, living in schools, and adults can reach a length of 2 meters.

[0003] Leopard sea bass, a prized aquaculture fish, is highly sought after by consumers both domestically and internationally, enjoying a broad market demand. Currently, the wild population of leopard sea bass has declined significantly due to overfishing, and my country has yet to achieve a breakthrough in the technology for large-scale spawning in indoor cement ponds for leopard sea bass production. The breeding of leopard sea bass has traditionally relied on marine net cages for spawning, with parent fish raised on offshore fish rafts and naturally spawning and fertilizing in the cages. This method is heavily influenced by natural environmental conditions such as water temperature, wind, waves, and hydrology, resulting in a low success rate. Furthermore, the asynchronous maturation and hatching times of the parent fish, along with low spawning batches, are problems in the artificial breeding of leopard sea bass parent fish. Additionally, the use of nutritional fortification combined with hormone injections to induce maturation and spawning in leopard sea bass parent fish on fish rafts leads to insufficient egg quality. For example, Chinese invention patent CN114766396A discloses a method for nutritional fortification to promote the development of juvenile red snapper. However, this method primarily targets the growth and development of juvenile fish, not the gonadal development and reproduction of broodstock. Furthermore, the induced spawning method for broodstock on marine fish rafts is a non-natural spawning method, which is difficult to operate, causes significant damage to the broodstock, results in severe losses, and produces poor-quality gametes (over-mature eggs with low fertilization rates). Currently, there are no reports on indoor, factory-scale, natural spawning and breeding methods for leopard-gill sea bass. Therefore, breakthroughs in indoor natural spawning and breeding technology for leopard-gill sea bass, enabling factory-scale, mass spawning, reducing damage to broodstock and operational difficulties, are of significant practical importance for promoting large-scale, indoor artificial breeding of leopard-gill sea bass. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a method for regulating the natural spawning of leopard gill sea bass broodstock in an indoor factory setting. Through a combination of land-sea relay cultivation and artificial reproductive regulation, the gonads of the broodstock mature synchronously and spawn naturally in an indoor cultivation pond, thereby obtaining high-quality fertilized eggs for mass natural spawning and providing a sufficient supply of high-quality fertilized eggs for the large-scale production of leopard gill sea bass fry.

[0005] The technical solution of this invention is as follows:

[0006] The method for regulating the natural spawning of broodstock in factory-style indoor environments for leopard-gill sea bass includes broodstock selection, transportation, rearing, and reproductive regulation of natural spawning, specifically comprising the following steps:

[0007] S1 Parent Fish Selection: Select parent fish with normal body color, active and healthy;

[0008] S2 Broodstock Cultivation: Broodstock are cultivated using a combination of marine net cages and land-based industrialized indoor water culture methods. Specifically, when the natural seawater temperature is above 23℃, the broodstock are transferred to marine net cages for cultivation; when the natural seawater temperature is above 28℃, the broodstock are transferred to land-based industrialized aquaculture workshops for indoor cultivation.

[0009] S3 Reproductive Regulation Natural Spawning: By regulating the water temperature, light cycle, and nutrient fortifier composition of broodstock in factory-style indoor culture, the gonads of broodstock are regulated to mature and spawn naturally indoors.

[0010] S31 Water Temperature Control: Starting 45 days before spawning, the water temperature for raising parent fish is artificially controlled. The temperature is gradually increased from 21-22℃ to 24-25℃ at a rate of 0.5℃ / week to induce spawning. Then, the temperature is increased to 26-27℃ at a rate of 0.5℃ / week and maintained at this temperature for one month. Finally, the temperature is decreased at a rate of 0.5℃ / week until spawning ends.

[0011] S32 Light Cycle Control: The workshop interior adopts a canopy design that allows light to pass through, providing a natural light source with a maximum light intensity of 1500 Lx.

[0012] S33 Nutritional Fortifier Composition: 45 days before spawning, the feed of fresh mackerel, small yellow croaker, squid, and nutritional fortifier is used to regulate and promote the development of the gonads and gametes of the parent fish, advance the development process, improve the quality of gametes, and obtain high-quality fertilized eggs.

[0013] Preferably, in step S1, the selected parent fish should be at least 3 years old, with a total length of 50-60cm and a weight of 1.75-2.5kg.

[0014] Preferably, in step S2, during offshore cage culture, the dissolved oxygen is ≥6.5 mg / L, the salinity is 33-34, and the broodstock culture density is 2-3 kg / m³.3 .

[0015] Preferably, in step S2, the land-based factory-style indoor flowing water culture method is controlled in terms of culture facilities, sex ratio, culture density, feed, and culture conditions; wherein, the culture facilities are indoor flowing water cement culture ponds set up in the land-based factory-style aquaculture workshop, the sex ratio is (2-3):1 for female fish, and the culture density is 2-3 kg / m³. 3 The cultivation conditions are flowing water cultivation, with a water exchange rate of 6m³. 3 / h, daily water exchange rate 200-300%, dissolved oxygen ≥6mg / L, pH=8-8.2, salinity 28-30, regular pool cleaning and bottom brushing; water temperature increases from the initial 21-22℃ to 24-25℃ at a rate of 0.5℃ / week.

[0016] Preferably, in step S2, during the marine cage culture stage, the feed includes 80-85 wt.% fresh triggerfish, 15-20 wt.% squid, and a nutrient fortifier accounting for 5 wt.‰ of the total weight of the fresh triggerfish and squid. The feeding amount is maintained at 3-4% of the fish's body weight, and feeding is carried out once every other day.

[0017] Preferably, in the land-based factory-style indoor flowing water culture method in step S2 and in step S33, the feed includes 40-45 wt.% of fresh mackerel, 40-45 wt.% of small yellow croaker, 10-20 wt.% of squid, and a nutrient fortifier accounting for 5 wt.‰ of the total weight of the fresh mackerel, small yellow croaker, and squid. The feeding amount is 3-4% of the body weight of the parent fish, and feeding is done once every two days until spawning ends.

[0018] Preferably, the nutritional fortifiers include 30-40 wt.% lecithin, 30-40 wt.% astaxanthin, and 20-40 wt.% multivitamins. ， Multivitamins include vitamin A, vitamin C, and vitamin E.

[0019] Preferably, in step S2, a recirculating aquaculture system (RAS) live fish transport vehicle is used to transfer the broodstock. The water temperature in the RAS live fish transport vehicle is controlled at a constant 21-22℃, DO ≥ 6 mg / L, and the stocking density of the broodstock is 70-80 kg / m³. 3 .

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The method of regulating the natural spawning of leopard gill sea bass broodstock in an industrialized indoor environment according to the present invention selects high-quality broodstock to construct breeding stock, and cultivates broodstock through land-sea relay, which ensures the development and accumulation of broodstock within a suitable temperature range, allowing broodstock to grow and develop under conditions closer to nature, resulting in high-quality broodstock cultivation, and providing a strong prerequisite for reproductive regulation of spawning.

[0022] 2. The method of regulating the natural spawning of leopard-gill sea bass broodstock in a factory-style indoor environment of the present invention, through water temperature regulation and natural light simulation of natural spawning conditions, coupled with continuous flowing water cultivation and nutritional enhancement measures, allows the broodstock to experience natural environmental conditions to the maximum extent in the factory-style aquaculture workshop, promoting the development of gonads and gametes of the broodstock, and ultimately achieving synchronous maturation of gonads in both male and female broodstock and realizing long-term natural spawning. This achieves precise control of reproductive regulation and spawning of leopard-gill sea bass broodstock, and obtains high-quality fertilized eggs in batches.

[0023] 3. The method of regulating the natural spawning of leopard-gill sea bass broodstock in an industrialized environment according to the present invention involves controlling the amount of feed and nutritional fortification. During the marine cage culture period, triggerfish, squid, and a 5‰ broodstock fortifier are fed at 3-4% of the broodstock's body weight to promote the growth and development of the broodstock. During the indoor reproductive regulation period, the feed is adjusted to mackerel, small yellow croaker, squid, and a 5‰ broodstock fortifier, with the feed rate maintained at 3-4% of the broodstock's body weight. Attention is paid to controlling the broodstock's fat intake to reduce the accumulation of visceral fat, thereby effectively promoting the full development and maturation of the gonads and obtaining high-quality fertilized eggs. Attached Figure Description

[0024] Figure 1 This invention describes the water temperature change trend during the marine cage culture of leopard gill bream broodstock in 2024.

[0025] Figure 2 This invention describes the trend of water temperature changes during indoor rearing of leopard gill bream broodstock in a factory-style aquaculture facility in 2024.

[0026] Figure 3 This is the trend of spawning volume of leopard gill sea bass broodstock in 2024 in this invention. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0028] Example 1

[0029] This embodiment uses the factory-style indoor breeding of leopard gill bream broodstock from Laizhou Mingbo Aquatic Products Co., Ltd. as an example for illustration.

[0030] In 2024, research was conducted at Laizhou Mingbo Aquatic Products Company on indoor culture and reproductive regulation of broodstock of leopard-gill sea bass, successfully obtaining a large batch of high-quality fertilized eggs. The specific implementation process is as follows:

[0031] S1 Parent Fish Selection

[0032] Based on the criteria of being free from injury and ulceration, having normal body color, and being lively and healthy, broodstock with normal body color and lively and healthy were selected from wild leopard gill sea bass caught in the South China Sea. Among them, 68 three-year-old broodstock with a total length of 50-60cm and a weight of 1.75-2.5kg were selected to form a breeding population.

[0033] S2 Broodstock Breeding

[0034] The broodstock are cultivated using two methods: offshore net cages and land-based industrialized indoor flowing water systems.

[0035] like Figure 1 As shown, on January 1, 2024, when the natural seawater temperature reached 23℃, the parent fish were transferred to deep-sea, wave-resistant net cages for summer rearing. The net cages were square wooden structures, measuring 4.5m × 4.5m × 3m, with a rearing density of 2.5kg / m³. 3 .

[0036] During the marine cage culture period, the broodstock feed consisted of 80 wt.% triggerfish, 20 wt.% squid, and a nutrient fortifier comprising 5 wt.‰ of the total weight of the chilled triggerfish and squid. The feeding amount was 3-4% of the fish's body weight, fed every two days at 10:00 AM. Culture conditions: dissolved oxygen ≥6.5 mg / L, salinity 33-34, and good broodstock development.

[0037] On April 14, 2024, when the natural seawater temperature exceeded 28℃, the broodstock were transferred to a land-based intensive aquaculture facility for indoor rearing. The broodstock were housed in 6.85m × 6.85m × 2m cement rearing tanks (effective volume 80m³) within the land-based intensive aquaculture facility. 3 The fish were raised indoors at a density of 2 kg / m³, with 68 parent fish placed in the rearing tank. 3 The sex ratio of females to males was 2:1. Broodstock were transferred using a recirculating aquaculture system (RAS) live fish transport vehicle, with the water temperature in the RAS vehicle maintained at a constant 22℃, DO ≥ 6-7 mg / L, and a broodstock density of 73 kg / m³. 3 .

[0038] During indoor rearing, the broodstock were fed a diet consisting of 40 wt.% fresh mackerel, 40 wt.% small yellow croaker, and 20 wt.% squid, along with a nutrient fortifier comprising 5 wt.‰ of the total weight of the fresh mackerel, small yellow croaker, and squid. The feeding amount was 3-4% of the broodstock's body weight, given every two days at 1 PM. Other rearing conditions: flow-through rearing with a water exchange rate of 6 cubic meters per second. 3 / h, daily water exchange rate 200%, dissolved oxygen ≥6mg / L, pH=8-8.2, salinity 28-30, regular pool cleaning and bottom brushing; water temperature increases from the initial 21-22℃ to 24-25℃ at a rate of 0.5℃ / week.

[0039] S3 Reproductive Regulation Natural Ovulation

[0040] After being transferred to the flow-through culture tank of the land-based factory aquaculture workshop on April 14, 2024, the broodstock's gonads were regulated to mature and spawn naturally using methods such as artificial temperature control, natural light, and nutritional enhancement.

[0041] S31 Water Temperature Control

[0042] Starting April 14, 2024, high-temperature steam was heated by a boiler in a thermal power plant and delivered to the workshop pipelines. Combined with the workshop's heat exchangers, waste heat from the workshop's exhaust water was used to regulate the water temperature for broodstock rearing, achieving water conservation, energy saving, and environmental friendliness. Figure 2 As shown, the temperature was raised from 21-22℃ on April 15th at a rate of 0.5℃ / week to 24-25℃ on May 28th to induce spawning. The temperature continued to rise at a rate of 0.5℃ / week for one month until it reached 26-27℃. After maintaining this temperature for one month, the temperature began to drop at a rate of 0.5℃ / week until spawning ended.

[0043] S32 Irradiance Regulation

[0044] The workshop interior features a canopy design that allows natural light to pass through, with a maximum light intensity of 1500 Lx.

[0045] S33 Nutritional Fortification

[0046] After transferring the broodstock to a factory-style indoor flowing-water rearing tank, and synchronizing with temperature and light control, the broodstock's diet was adjusted to a mixture of 40 wt.% fresh mackerel, 40 wt.% small yellow croaker, and 20 wt.% squid, fed at a rate of 3-4% of their body weight every two days. Simultaneously, a nutritional fortifier consisting of 40 wt.% lecithin, 40 wt.% astaxanthin, and 20 wt.% complex vitamins was added to the mixed diet at a rate of 5 wt.‰ of the feed amount, mixed and stirred onto the surface of the fresh fish to enhance the broodstock's nutrition and improve gamete quality.

[0047] Through the above reproductive regulation measures, the gonads of the broodstock developed well and reached synchronous maturity. After 45 days of regulation, the broodstock naturally spawned in the indoor rearing pond, yielding 15.6 kg of high-quality, floating fertilized eggs. The spawning period lasted 174 days (e.g., Figure 3 As shown in the figure, the average fertilization rate is over 95% and the hatching rate is over 80%, providing a sufficient supply of high-quality fertilized eggs for large-scale seedling cultivation.

[0048] Comparative Example 1

[0049] Another batch of broodstock of the same number as in Example 1 was cultured indoors in a land-based industrialized workshop under the same conditions and timeframes for reproductive regulation. The difference from Example 1 was that in steps S2 and S3, the broodstock were placed in a recirculating aquaculture tank, and the culture conditions were recirculating aquaculture. The results showed that the culture method in Comparative Example 1 did not yield fertilized eggs during 2024.

Claims

1. A method for regulating natural spawning of Cephalopholis leopardus broodstock in factory-like indoor conditions, characterized by, The method comprises parent fish selection, parent fish transportation, parent fish cultivation and natural spawning by reproductive regulation, and specifically comprises the following steps: S1. Parent fish selection: selecting parent fish with normal body color and active and healthy; S2. Parent fish cultivation: cultivating the parent fish in offshore net cages and land-based factory indoor flow water cultivation methods, i.e., when the natural seawater temperature is higher than 23℃, the parent fish are transferred to offshore net cages for cultivation; when the natural seawater temperature is higher than 28℃, the parent fish are transferred to land-based factory cultivation workshops for indoor cultivation; S3. Natural spawning by reproductive regulation: regulating the water temperature, light cycle and nutritional enhancer composition of the parent fish indoor cultivation to regulate the sexual gland maturation of the parent fish and natural spawning indoors; S31. Water temperature regulation: starting to artificially regulate the water temperature of the parent fish cultivation pool 45 days before spawning, gradually increasing the temperature at a rate of 0.5℃ / week from 21-22℃ to 24-25℃ to make the parent fish start spawning, then continuing to increase the temperature at a rate of 0.5℃ / week to 26-27℃, and then decreasing the temperature at a rate of 0.5℃ / week to the end of spawning; S32. Light cycle regulation: the land-based factory cultivation workshop is designed with a roof that can transmit natural light, and the maximum light intensity is 1500Lx; S33. Nutritional enhancer composition: 45 days before spawning, the parent fish are fed with ice-fresh mackerel, small yellow croaker, squid and nutritional enhancer to regulate and promote the development of the parent fish gonads and gametes, improve the quality of the gametes, and obtain high-quality fertilized eggs.

2. The method of regulating natural spawning of Cephalopholis leopardus broodstock in factory-like indoor conditions according to claim 1, characterized in that, In step S1, the selected parent fish are 3 years old, with a total length of 50-60 cm and a weight of 1.75-2.5 kg.

3. The method of regulating natural spawning of Cephalopholis leopardus broodstock in factory-like indoor conditions according to claim 1, characterized in that, In step S2, when the offshore net cage is cultivated, the dissolved oxygen is ≥6.5 mg / L, the salinity is 33-34, and the broodstock cultivation density is 2-3 kg / m 3 .

4. The method of regulating natural spawning of Cephalopholis leopardus broodstock in factory-like indoor conditions according to claim 1, characterized in that, In step S2, in the land-based factory indoor flow water cultivation mode, the cultivation facilities, gender matching, cultivation density, bait feeding and cultivation conditions are controlled; wherein the cultivation facilities adopt indoor flow water cement cultivation pools set up in the land-based factory cultivation workshop, the gender matching is that the number ratio of female fish to male fish is (2-3):1, the cultivation density is 2-3 kg / m 3 ; and the cultivation conditions are flow water cultivation, water exchange amount is 6 m 3 / h, daily water exchange rate is 200-300%, dissolved oxygen is greater than or equal to 6 mg / L, pH is 8-8.2, salinity is 28-30, and the pool is cleaned and the bottom is brushed at regular time; and the water temperature is increased from the initial 21-22℃ to 24-25℃ at a temperature increasing rate of 0.5℃ / week.

5. The method of regulating the natural spawning of Cephalopholis leopardus broodstock in a factory building according to claim 1, characterized in that, In step S2, during the offshore net cage cultivation stage, the feed includes 80-85wt.% of ice-fresh sardines, 15-20wt.% of squid and 5wt.% of nutritional enhancer based on the total mass of ice-fresh sardines and squid, and the feeding amount is kept at 3-4% of the fish body weight, and the feeding is performed once every other day.

6. The method of regulating the natural spawning of Cephalopholis leopardus broodstock in a factory building according to claim 1, characterized in that, In the land-based factory indoor flow water cultivation method of step S2 and step S33, the feed includes 40-45wt.% of ice-fresh mackerel, 40-45wt.% of small yellow croaker, 10-20wt.% of squid and 5wt.% of nutritional enhancer based on the total mass of ice-fresh mackerel, small yellow croaker and squid, and the feeding amount is 3-4% of the parent fish body weight, and the feeding is performed every two days until the end of spawning.

7. The method of regulating natural spawning of Cephalopholis leopardus broodstock in factory-like indoor conditions according to claim 1, 5 or 6, characterized in that, The nutritional enhancer includes 30-40wt.% of lecithin, 30-40wt.% of astaxanthin and 20-40wt.% of compound vitamins.

8. The method of regulating natural spawning of Cephalopholis leopardus broodstock in factory-like indoor conditions according to claim 1, characterized in that, In step S2, the circulating water live fish transport vehicle is used when transferring the parent fish, the water temperature of the circulating water live fish transport vehicle is controlled to be constant at 21-22℃, DO≥6mg / L, and the parent fish density is 70-80kg / m 3 .

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