Pomfret breeding method suitable for autumn environment

Abstract

The invention relates to the technical field of aquatic breeding and cultivation, and particularly discloses a pomfret breeding method suitable for autumn environment, which comprises the following steps: step 1: selecting artificially bred F1-generation or F2-generation pomfret as a parent, the weight of female pomfret is greater than or equal to 150g, the weight of male pomfret is greater than or equal to 100g, and the male-female ratio is 1: 1-1: 1.5; if wild parents are adopted, the wild parents can be used after being domesticated for more than three months and being subjected to health observation, the parents are subjected to health screening, and unhealthy parents carrying pathogens are removed. According to the pomfret breeding method suitable for the autumn environment, through the whole-process refined operation steps of parent selection and intensive breeding, the source of the fry is grasped, and high-quality and good fry are bred. According to the method, the initial breeding quality of autumn pomfret breeding is improved, the reproductive performance of parents is guaranteed, the requirement for gonad development of the autumn parents is met due to the fact that the steps of intensive parent breeding are added, and the uniformity of the specification of the offspring seeds is effectively improved by simulating the growth conditions matched with the autumn environment and adopting the method of combining batched egg laying and grading breeding.

Description

Technical Field

[0001] This invention relates to the field of aquatic seedling cultivation and breeding technology, specifically a method for raising silver pomfret seedlings suitable for autumn environments. Background Technology

[0002] Silver pomfret is an important economic species for marine aquaculture in my country, with continuously growing market demand. The supply capacity of seedlings directly impacts the scale and stability of the industry's development. Currently, silver pomfret seedling production is concentrated in spring and summer, a well-known practice within the industry. However, seedlings obtained through spring incubation must endure the subsequent high temperatures of summer. During this period, water temperatures remain consistently high and fluctuate frequently, easily inducing bacterial, parasitic, and stress-related diseases, leading to increased seedling mortality and unstable survival rates. Simultaneously, high temperatures require significant investment in aeration, oxygenation, and cooling equipment to maintain water quality and the growth environment, significantly increasing energy consumption and management costs. Furthermore, the high-temperature environment exacerbates seedling differentiation, resulting in uneven size, decreased physical condition and resistance, making it difficult to guarantee the quality of marketable seedlings.

[0003] Due to the aforementioned factors, the existing spring and summer seedling cultivation model has significant shortcomings in terms of survival rate, uniformity of size, and stability of commercial seedlings, making it difficult to meet the needs of large-scale industrial development.

[0004] In contrast, the water temperature in the sea area gradually decreases and stabilizes in autumn, with smaller fluctuations in the physicochemical indicators of the water and a significant reduction in overall pathogen pressure, providing a safer and more stable environment for the cultivation of silver pomfret fry. More importantly, fry cultivated in autumn can successfully overwinter under proper management and become marketable fish around the time of the fishing ban the following year. During the fishing ban, natural catch resources are limited, market supply contracts temporarily, while consumer demand remains stable or even increases, resulting in silver pomfret market prices typically remaining relatively high throughout the year. The autumn fry cultivation model allows farmed products to precisely target this time window, achieving "staggered market entry and realization of price advantages," significantly improving the economic return per unit of output, and enhancing the resilience of aquaculture operators to market fluctuations. From an industrial structure perspective, this model helps optimize resource allocation and is of great significance for increasing the overall added value of the silver pomfret industry.

[0005] However, the industry currently lacks a systematic silver pomfret breeding technology system tailored to the environmental characteristics of autumn. Factors such as changes in water temperature gradients, shortened daylight hours, and adjustments in microbial community structure during the autumn season make it difficult to consistently control the hatching rate of fertilized eggs, embryonic malformation rate, seedling survival rate, and size consistency under existing technological conditions. Simultaneously, the industry lacks a replicable and scalable standardized autumn breeding process. Autumn seedlings obtained under existing processes tend to have weaker physical constitutions and insufficient overwintering ability, further impacting the following year's market performance and aquaculture yield. Ultimately, this restricts the capacity for large-scale autumn seedling supply and fails to meet the industry's actual demand for high-quality autumn silver pomfret seedlings.

[0006] Therefore, it is necessary to systematically optimize and innovate existing silver pomfret seedling cultivation techniques, taking into account the environmental characteristics and industry window advantages of autumn, to construct a stable, efficient, and scalable seedling cultivation method suitable for autumn conditions. This would achieve the comprehensive goals of high survival rate, high uniformity, and high overwintering survival rate, and support the industry's demand for high-value market supply during the closed season. To address the above issues, innovative designs are urgently needed based on existing autumn silver pomfret seedling cultivation methods. Summary of the Invention

[0007] The purpose of this invention is to provide a method for raising silver pomfret seedlings suitable for the autumn environment, in order to solve the problems mentioned in the background art, such as changes in water temperature gradient, shortened daylight hours, and adjustments in microbial community structure during the autumn seasonal transition. These factors make it difficult to stably control the hatching rate of fertilized eggs, the rate of embryonic malformation, the survival rate of seedlings, and the consistency of size in autumn seedling raising under the existing conditions. Furthermore, the autumn seedlings obtained by the existing process have weak physical foundation and insufficient overwintering ability, which further affects the market performance and breeding output in the following year.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for raising silver pomfret seedlings suitable for autumn environments, comprising the following steps: Step 1: Parent Selection Select artificially bred F1 or F2 generation silver pomfret as parent fish, with females weighing ≥150g and males weighing ≥100g, and a male-to-female ratio of 1:1 to 1:1.5; if wild parent fish are used, they must be domesticated and observed for more than 3 months before use, and the parent fish must be screened for health to remove those carrying pathogens or that are unhealthy. Step 2: Parental Enhancement Breeding For the qualified parent stock in step 1, implement refined and enhanced management of feed, light, temperature and water quality. Stabilize the water temperature at 18~20℃ and maintain it for 50~60 days. Feed high-protein mixed feed, control the light intensity at 100~500 lux, change the water volume at 20%~25% per day, maintain dissolved oxygen ≥6.0mg / L, and monitor gonadal development until stage 5 maturity. Step 3: Induction of ovulation and fertilization After the female fish showed signs of natural spawning, the water temperature was maintained at 18-19℃ for about 2 weeks to induce mass spawning of the parent fish. The fertilized eggs were then incubated in a medium-strong light environment with a water temperature of 20.0℃±0.5℃, dissolved oxygen ≥6.5mg / L, and salinity of 20‰-30‰. This resulted in each 150g female fish laying approximately 10,000 eggs at a time, with a fertilization rate ≥75% and a hatching rate ≥80%. Step 4: Seedling cultivation The hatched fry from step 3 are transferred to a nursery pond, where the temperature is gradually increased to 22℃±1.5℃ at a rate of 0.5℃ / day. The basic growth environment is maintained with dissolved oxygen ≥6.5mg / L and salinity 20‰~30‰. Then, the fish are graded and fed in stages according to their growth cycle. At the same time, disease control is carried out during the seedling stage. Finally, commercial seedlings with a total length ≥3.0~5.0cm, a weight ≥1.5g, and a total length difference ≤20% within the same breeding unit are cultivated. Step 5: Overwintering pretreatment of commercially available seedlings The water temperature in the seedling pond was gradually reduced to 15-18℃ at a rate of 1℃ / day to maintain stable water quality. The seedlings were then fed 400-700μm high-protein compound feed to enhance their physical condition and improve their overwintering adaptability.

[0009] By adopting the above technical solutions, a complete process system for silver pomfret breeding adapted to the autumn environment can be constructed, realizing large-scale and standardized silver pomfret breeding in autumn, improving the uniformity of seedling size and overwintering adaptability, reducing production and management costs, and allowing the seedlings to be marketed during the fishing ban period of the following year, significantly improving the economic benefits of aquaculture and achieving stable production and supply of silver pomfret seedlings throughout the year.

[0010] Preferably, in step 1, the parent organisms undergo pathogen detection and health screening. The detection targets include individuals of iridovirus, luminous bacillus of mermaids, neuronecrosis virus, dactyloides, amylodinium, cryptocaryon, and ciliates. The parent organisms must have intact surfaces, tightly packed scales, no swelling, hemorrhage, or necrosis of internal organs, and bright red gills without abnormal mucus or parasites.

[0011] By adopting the above technical solution, the health quality of parent plants can be controlled from the source of seedling cultivation, completely eliminating pathogen carriers and unhealthy parent plants, preventing the spread of pathogens carried by parent plants to offspring, reducing the probability of disease occurrence during seedling cultivation, ensuring the excellent reproductive performance of parent plants, and laying the foundation for high fertilization rate and high hatching rate in the future.

[0012] Preferably, the mixed feed in step 2 is composed of shrimp paste: fish meat: compound feed in a mass ratio of 3:2:5, wherein the compound feed has a crude protein content of ≥50% (dry basis), a total DHA+EPA content of ≥1.8%, and a taurine content of ≥0.8%.

[0013] By adopting the above technical solution, the precise formulation and nutritional limitation of high-protein compound feed can fully meet the nutritional needs of silver pomfret parent fish for gonad development in autumn, such as high protein and high unsaturated fatty acids. This effectively promotes the rapid and synchronous development of parent gonads, improves the spawning efficiency and egg quality of parent fish, and provides a high-quality material basis for the normal hatching of fertilized eggs.

[0014] Preferably, the illumination control in step 2 is divided into two stages: Gonadal development promotion period: photoperiod of 15 hours of light: 9 hours of darkness, light intensity of 500±50 lux; Spawning induction period: photocycle of 8 hours of light: 16 hours of darkness, light intensity of 200±30 lux.

[0015] By adopting the above technical solution, the light parameters are precisely controlled in stages to simulate the natural light rhythm changes in autumn. This precisely stimulates the activity of the hypothalamus, pituitary gland, and gonadal axis in the parent fish, which not only promotes the efficient development and maturation of the gonads, but also induces the parent fish to spawn synchronously, improves the concentration of spawning and the synchronicity of ovulation, reduces the proportion of unfertilized eggs, and increases the fertilization rate.

[0016] Preferably, the water quality control parameters in step 2 are as follows: Dissolved oxygen: maintained in the range of ≥6.0 mg / L, preferably 6.5~7.5 mg / L; pH value: Controlled range of 7.8~8.6, daily fluctuation ≤0.3; When pH < 7.8, add an appropriate amount of sodium bicarbonate to adjust; when pH > 8.6, reduce excessive algae growth and avoid alkali poisoning. Use an online pH monitor for real-time monitoring to prevent osmotic stress caused by drastic fluctuations; Ammonia nitrogen: Total ammonia nitrogen ≤ 0.2 mg / L, non-ionized ammonia ≤ 0.02 mg / L; When the ammonia level exceeds the standard, measures such as changing the water (10% to 20% of the water volume per change), adding nitrifying bacteria preparations or activated carbon adsorption should be taken to prevent ammonia poisoning from inhibiting feeding and gonadal development. Nitrite: ≤0.01 mg / L; When the concentration is >0.01mg / L, immediately stop feeding high-protein feed, increase the frequency of water changes, and add compound nitrifying bacteria to promote the conversion of nitrite to nitrate; Salinity: maintained within the range of 20-30‰, with daily fluctuations ≤ ±2‰.

[0017] By adopting the above technical solutions, key water quality parameters for parent stock cultivation can be controlled, the physicochemical environment of the water body can be kept stable, stress response of parent fish caused by water quality fluctuations can be avoided, normal feeding and gonadal development of parent fish can be guaranteed, pathogen proliferation caused by water quality deterioration can be reduced, mortality rate during the parent stock cultivation stage can be reduced, and parent stock reproductive performance can be improved.

[0018] Preferably, in step 2, temperature control is achieved through precise temperature control using an air-source heat pump, with a start-up threshold of: Heating mode: Starts when the water temperature drops to 17.5~17.7℃; Cooling mode: Starts when the water temperature reaches 20.4~20.6℃; Emergency procedures: If the water temperature does not return to the target range for 2 consecutive hours, manually intervene to adjust the water flow or change the water.

[0019] By adopting the above technical solution, an air source heat pump is used to achieve precise and automated water temperature control, strictly controlling the daily water temperature fluctuation range, providing a stable temperature environment for the development of parent gonads, and promoting uniform gonad development.

[0020] Preferably, the incubation conditions for the fertilized eggs in step 3 are: water temperature 20.0±0.5℃, dissolved oxygen ≥6.5mg / L, salinity 20~30‰, and medium to strong light environment.

[0021] By adopting the above technical solution, the optimal temperature, oxygen, salinity and light environment for the hatching of silver pomfret fertilized eggs is matched, which is fully adapted to the physiological needs of embryonic development in autumn, effectively improves the hatching rate of fertilized eggs, reduces the rate of embryonic malformation, and ensures that the hatched fry are healthy, laying the foundation for improving the survival rate of subsequent seedling cultivation.

[0022] Preferably, the seedling cultivation stage in step 4 includes the following grading nodes: First grading stage: 35-40 days after hatching, seedlings are screened according to their total length. Seedlings with a total length ≥ 2.0 cm are transferred to a rearing unit mainly fed with formulated feed, while seedlings with a total length < 2.0 cm are reared separately and supplemented with live / mixed feed. After grading, the difference in total length of seedlings within the same rearing unit should be ≤ ± 20%. Second grading stage: Approximately 60 days after hatching, the animals are graded and cultivated according to their total length of 5.0~6.0cm and ≥6.0cm, with the total length difference controlled to ≤±15%.

[0023] By adopting the above technical solution and cultivating seedlings at two nodes, the size difference of seedlings can be precisely controlled, effectively reducing the risk of cannibalism of silver pomfret seedlings and improving the uniformity of seedling size.

[0024] Preferably, the feed transition stage during the seedling cultivation stage is as follows: Days 0-20 after hatching: Feed rotifers; 20-35 days after hatching: Feed with Artemia nauplii and microencapsulated formulated feed with a particle size of 200-300μm, gradually transitioning the ratio of live bait to formulated feed to 50% each; 35-40 days after hatching: Gradually reduce live feed for seedlings with a total length ≥2.0cm and switch to formulated feed as the main source of feed; After 40 days of incubation: feed fully formulated feed; the feed particle size gradient from 40 to 60 days is 300 to 400 μm, and the feed particle size gradient after 60 days is 400 to 700 μm.

[0025] By adopting the above technical solution, a step-by-step feed transition program is designed according to the feeding habits and nutritional needs of seedlings at different growth stages, so as to achieve a smooth transition from live bait to formulated feed, reduce the stress response of seedlings during the transition, and improve the survival rate of seedlings.

[0026] Preferably, the seedling cultivation stage is also equipped with disease control facilities, including: Ultraviolet sterilization device: 30W / ton of water; Probiotic addition: Add 1 mL / m³ of Bacillus subtilis or compound Bacillus subtilis weekly, with an effective live bacteria concentration ≥ CFU / mL; Drug prevention and control: When bacterial enteritis occurs, mix florfenicol with feed and administer 5-10 mg / kg of feed for 3-5 consecutive days; During medication, the daily water change should be controlled at 15% to 20%; large-scale water changes should be suspended within 24 hours before and after seedling grading, and only bottom sludge suction and cleaning should be carried out.

[0027] By adopting the above technical solutions, the pathogen load in water bodies can be reduced from multiple dimensions, the reproduction of harmful bacteria can be inhibited, the probability of bacterial diseases occurring in seedlings in autumn can be reduced, and the survival rate of seedlings can be improved.

[0028] Compared with the prior art, the beneficial effects of the present invention are: a method for raising silver pomfret seedlings suitable for autumn environments: 1. Through meticulous operation steps in the entire process of parent selection and enhanced cultivation, a solid foundation for high-quality seedling cultivation is established from the source of seedling production, improving the initial breeding quality of silver pomfret seedlings in autumn. By strictly selecting parent specifications and conducting comprehensive pathogen and health screening, unqualified parent stock is eliminated, eliminating the risk of pathogen transmission. Targeted enhanced cultivation steps for parent stock, through precise formulation and dynamic feeding of high-protein compound feed, meet the needs of parent gonadal development in autumn. Combined with staged light regulation, precise temperature control by air source heat pumps, and refined management of multi-indicator water quality, growth conditions adapted to the autumn environment are simulated, effectively promoting the synchronous development of parent gonads from the end of stage 2 to stage 5, improving gonadal development rate and ovulation synchronicity. Furthermore, by adopting a combination of batch spawning and graded cultivation, the uniformity of seedling specifications is effectively improved, thus improving the quality of silver pomfret seedlings. 2. Through a series of supporting steps including induced spawning and hatching, and seedling cultivation, the survival rate and size uniformity of silver pomfret seedlings are improved, while reducing energy consumption and management costs in seedling production. After induced spawning, the hatching process is carried out by adapting the temperature, oxygen, salinity, and light conditions to the autumn embryonic development, ensuring the robust health of the juvenile fish. During the seedling cultivation stage, the environmental control step of gradient temperature increase creates suitable growth conditions for the juvenile fish. The two-node graded cultivation step effectively controls the size difference of the seedlings and reduces the risk of cannibalism. The phased feed transition step achieves a smooth transition of the juvenile fish from live food to formulated feed, reducing transition stress. The multi-dimensional disease prevention and control steps reduce the risk of pathogens during the seedling stage and improve the survival rate of the seedlings. 3. Furthermore, the overwintering pretreatment steps, through gradual cooling and feeding with high-protein compound feed, strengthened the physical condition of autumn seedlings, improved their low-temperature resistance and disease resistance, solved the problem of insufficient overwintering capacity of existing autumn seedlings, realized the improvement of seedling overwintering capacity and stable production and efficiency at the industry level, and achieved stable production and supply of silver pomfret seedlings throughout the year. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the seedling cultivation process of the present invention; Figure 2 This is a schematic diagram of the seedling cultivation process of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figures 1-2 The present invention provides a technical solution: a method for raising silver pomfret seedlings suitable for autumn environment; Example 1: Parental selection and health screening This example illustrates the initial stage of autumn silver pomfret breeding. Through standardized parent stock selection, source control, and comprehensive health testing, the genetic quality and egg-laying potential of the parents are guaranteed, laying the foundation for subsequent breeding. Parental origin and specification screening Artificially bred F1 or F2 generation silver pomfret are preferred as parent stock for seedling raising; if wild silver pomfret parent stock is used, it must be domesticated indoors for more than 3 months and continuously observed for health, and only after confirming that its feeding and swimming behavior is normal can it be included in the screening range.

[0032] Parent individuals meeting the following specifications were selected: females were cultured for ≥18 months and weighed ≥150g, and males were cultured for ≥15 months and weighed ≥100g. The male-to-female ratio of the parent stock was 1:1.5, which was the optimal ratio verified by comparative experiments. The experimental data are shown in Table 1, which can achieve a stable fertilization rate of ≥75%. If the culture conditions are limited, a male-to-female ratio of 1:1 to 1.5 is an effective range. Parental health screening The selected parent animals undergo comprehensive health testing to eliminate pathogen carriers and unhealthy individuals. The testing requirements are as follows: Pathogen detection: Standard industry methods were used to detect iridovirus, luminescent bacteria, neuronecrosis virus, Gyrodactylus, Amylodinium ovale, Cryptocaryon irritans, and ciliates to ensure that the parent plants were free of the above pathogens. Physical examination: The body surface is intact, the scales are tightly packed, and the color is the normal body color of silver pomfret. There is no mechanical damage, abnormal spots, or excessive mucus secretion. Internal organ examination: Dissection and microscopic examination of the liver, spleen, and kidneys revealed no enlargement, hemorrhage, necrosis, or nodular lesions; Gill examination: The gill filaments are intact, bright red in color, without any parasites attached, gill filaments stuck together or covered with excessive mucus, and the gill rakers are not blocked.

[0033] Table 1 Comparative experimental data on fertilization rate of silver pomfret with different male-to-female ratios Experimental description: The parental specifications and cultivation environment were completely identical in each group, with the only variable being the male-to-female ratio; each group was repeated 5 times, and artificial insemination was used. The fertilization rate was calculated by counting the number of fertilized eggs and the total number of eggs. As the proportion of female fish increases, the fertilization rate gradually increases. A male-to-female ratio of 1:1 or 1:1.5 can achieve a relatively high and stable fertilization rate.

[0034] Example 2: Refined Enhancement Cultivation of Parental Lines This embodiment involves intensive cultivation of the qualified parent stock from Example 1 for 50-60 days. Through precise control of feed, light, temperature, and water quality, the parent stock's gonads are promoted to develop synchronously from the end of stage 2 to stage 5 maturity. Throughout the process, samples are taken every 5 days for microscopic examination of gonadal development to ensure that the parent stock lays eggs synchronously in batches. The core control parameters and operations are as follows: Feeding regulation High-protein compound feed was used for feeding, with the feed composed of shrimp paste: fish meat: compound feed in a mass ratio of 3:2:5. The crude protein content of the compound feed was ≥50% (dry basis), and the testing method was in accordance with GB / T 6432-2018. The main raw material composition (by mass percentage) was: 40% high-quality white fish meal, 15% peeled low-temperature soybean meal, 12% wheat flour, 6% fish oil, 3% phospholipids, 2% vitamin premix, 2% mineral premix, and 2% choline, cholesterol, antioxidants, and other functional additives. The total DHA+EPA content in the feed was ≥1.8%, and the taurine content was ≥0.8% to support the accumulation of lipid droplets in oocytes and the quality of embryonic development. The shrimp paste is made from whiteleg shrimp or whiteleg shrimp (including shrimp heads), providing nutrients such as DHA / EPA; the fish meat is made from minced mackerel or sand eel, providing high-quality animal protein and unsaturated fatty acids needed for fish development; the compound feed is a powdered feed used to supplement vitamins and minerals in a balanced way and maintain a stable nutritional structure.

[0035] Feeding is done twice a day, at 07:00 and 15:00. The daily feeding amount is 1.5% to 3% of the total weight of the parent population. Fresh live bait (shrimp paste + fish meat) and formulated feed each account for 50% of the total feeding amount. The feeding rhythm is dynamically adjusted according to the breeding stage: 1.5% during the first 2 weeks of adaptation period, gradually increasing to 2% during the middle 2 weeks of promotion period, and maintaining 3% during the last 2 weeks of maturity period. It is advisable to finish feeding within 30 minutes of each feeding, and the uneaten feed rate should be controlled within 5%.

[0036] The ratio is finely adjusted according to the gonadal development stage: when transitioning from gonadal stage 2 to stage 4, the proportion of shrimp paste is temporarily increased to 4 parts to enhance protein supply; at the end of gonadal stage 4, the proportion of shrimp paste is reduced to 1 part to reduce the proportion of dystocia in the parent stock and improve ovulation synchronicity. During feeding, the feeding behavior of the parent animals should be observed in real time. If the feeding enthusiasm decreases or the amount of uneaten feed increases significantly, the feeding amount should be reduced immediately and the health status should be checked.

[0037] Phased control of illumination The entire process utilizes a combination of LED cool white light (5500K-6500K) and natural light, with light intensity controlled between 100 and 500 lux. This simulates the long-day ecological signals of autumn, continuously stimulating the activity of the hypothalamus-pituitary-gonadal axis (HPG axis) and promoting rapid gonadal development to maturity. The light intensity is precisely controlled in two stages according to the gonadal development stages, with light parameters measured at a distance of 30cm from the water surface. Gonadal development promotion period (from the start of intensive culture to 5 days before ovulation): photocycle of 15 hours of light and 9 hours of darkness, light intensity of 500±50 lux, light uniformity ≥85%, continuously stimulating the activity of the hypothalamus-pituitary-gonadal axis and promoting the maturation of oocytes and sperm. Spawning induction period (5 days before ovulation to the end of spawning): The photocycle is 8 hours of light and 16 hours of darkness, with a light intensity of 200±30 lux, lasting for 5 to 7 days, to induce the parent fish to enter the spawning behavior period synchronously and reduce the proportion of unfertilized eggs.

[0038] Precise temperature control An air source heat pump is used to achieve precise water temperature control, ensuring that the daily water temperature change is ≤1℃. After the natural water temperature drops, the water temperature is stabilized at 18~20℃ and maintained for 50~60 days to promote the development of the parent gonads from the end of stage 2 to stage 5. The effect of different low temperature maintenance durations on gonad development rate is shown in Table 2.

[0039] Table 2 Comparative experimental data on the effect of different durations of low temperature maintenance on gonadal development rate in silver pomfret. Experimental description: The parental specifications and cultivation environment were the same in each group, with the only variable being the duration of low temperature maintenance; each group was repeated 5 times, and after low temperature treatment, the individuals were dissected and examined under a microscope to count the proportion of individuals whose gonads developed to stage 5. Results analysis: The gonadal development rate gradually increased with the increase of the number of days of low temperature maintenance. Under the condition of 18-20℃, appropriately extending the low temperature maintenance time was beneficial to improving the gonadal development rate of the silver pomfret parents. The gonadal development rate reached 60%-70% after 60 days of maintenance, which was significantly higher than that of the 40-day group. Therefore, the optimal low temperature maintenance time is 50-60 days.

[0040] The start-up threshold of the air source heat pump is as follows: in heating mode, it starts automatically when the water temperature drops to 17.5~17.7℃, and in cooling mode, it starts automatically when the water temperature rises to 20.4~20.6℃. The actual start-up threshold verification data is shown in Table 3. Emergency operation requirements: When the water temperature is below 17.5℃, the water temperature should be manually monitored every 30 minutes while the heat pump is heating; when the water temperature is above 20.5℃, the oxygenation equipment should be turned on while the heat pump is cooling to reduce heat stress; if the water temperature does not recover to the target range of 18~20℃ for 2 consecutive hours, manual intervention such as water flow adjustment or partial water replacement should be performed immediately.

[0041] Table 3 Verification data of actual start-up threshold for air source heat pump temperature control Experimental instructions: The target water temperature was set at 18~20℃. Each group was repeated 5 times. The water temperature value when the heat pump was actually started was recorded to determine the optimal start-up threshold range. Results analysis: Using an air source heat pump for water temperature control simplifies equipment configuration and ensures stable water temperature during the breeding of silver pomfret parents, providing suitable conditions for gonad development. The preferred start-up threshold for the air source heat pump is: heating 17.5–17.7℃ and cooling 20.4–20.6℃.

[0042] Refined water quality management A daily monitoring and control water quality management system was established. Water quality parameters were tested and recorded daily at 08:00. The bottom of the cultivation pond was vacuumed once a day. An ultraviolet sterilization device was used to maintain the micro-ecological balance of the water body. The core water quality control parameters and control measures are as follows: Dissolved oxygen: Maintain within the range of ≥6.0 mg / L, preferably 6.5~7.5 mg / L. If it is below 6.0 mg / L, start microporous aeration or pure oxygen injection to increase oxygenation. pH value: The control range is 7.8~8.6, with daily fluctuation ≤0.3. When pH<7.8, sodium bicarbonate is added for adjustment, and when pH>8.6, excessive algal growth is controlled. Ammonia nitrogen: Total ammonia nitrogen ≤ 0.2 mg / L, non-ionic ammonia ≤ 0.02 mg / L. If the levels exceed the limits, replace 10% to 20% of the water in a single water change or add nitrifying bacteria preparations. Nitrite: ≤0.01mg / L. If the level exceeds the limit, stop feeding high-protein feed and add compound nitrifying bacteria agent. Salinity: Maintain within the range of 20~30‰, with daily fluctuations ≤±2‰. Use seawater of the same temperature and salinity when changing water. Water exchange operation: The daily water exchange volume is 20%~25% of the pool volume to avoid drastic fluctuations in water quality caused by large-scale water exchange.

[0043] Gonadal development monitoring and assessment The standard for determining the stage of gonadal development through anatomical microscopy is as follows: Female fish: At the end of stage 2, the egg diameter is 300~400μm, and the eggs are uniform and translucent; at stage 5 (before spawning), the egg diameter is 500~600μm, the eggs are plump and have low transparency; after the eggs absorb water and swell during the spawning period, the egg diameter is ≥1.3mm. Male fish: At the end of stage 2, the gonads are thread-like, translucent, and milky white; at stage 5, the semen is abundant, milky white, and thick, with sperm motility ≥90%.

[0044] Example 3: Induction of oviposition and hatching of fertilized eggs This embodiment is based on the parental lineage that has reached stage 5 of gonadal development in Example 2. It achieves high egg production, high fertilization rate, and high hatching rate by inducing mass synchronous egg production through temperature control and completing the hatching of fertilized eggs under a suitable environment. The specific operation is as follows: Mass spawning induction When microscopic examination reveals a small number of signs of natural spawning in the female fish, the water temperature in the rearing pond is maintained at 18-19℃ for about 2 weeks to induce the parent fish to spawn synchronously in batches. Each 150g female fish can produce about 10,000 fertilized eggs at a time, with a natural fertilization rate of ≥75%.

[0045] fertilized egg hatching Fertilized eggs are collected and transferred to a dedicated hatching tank. The hatching environment parameters are strictly controlled as follows: water temperature 20.0℃±0.5℃, dissolved oxygen ≥6.5mg / L, and salinity 20~30‰. A medium-strong light environment is used to ensure normal embryonic development. Drastic fluctuations in water temperature and salinity are avoided throughout the process. Unfertilized eggs are removed regularly. The hatching rate of fertilized eggs is ≥80%, and under optimal cultivation conditions, the hatching rate can reach over 82%. The hatched fry are robust and have no obvious deformities.

[0046] Example 4: Seedling cultivation and determination of commercial seedling specifications This embodiment involves standardized cultivation of the juvenile fish hatched in Example 3 for more than 60 days. Through environmental control, graded cultivation, phased feed transition, and comprehensive disease control, the uniformity of seedling size is improved, and qualified commercial-grade silver pomfret seedlings are finally cultivated. The specific operation is as follows: Basic growth environment regulation The hatched fry are transferred to standardized nursery ponds, where the temperature is gradually increased at a rate of 0.5℃ / day, eventually maintaining a water temperature of 22℃±1.5℃. Throughout the process, dissolved oxygen is maintained at ≥6.5mg / L, salinity at 20~30‰, and the water is kept clean and free of suspended matter. The nursery ponds are equipped with ultraviolet sterilization devices with a power of 30W / ton of water to continuously sterilize the water, reducing the basal load of bacteria and parasites. During the nursery period, dissolved oxygen is maintained stably through microporous aeration to avoid stress to the fry caused by hypoxia.

[0047] Seedling grading and cultivation Two key grading points are set up to control differences in seedling size and reduce the risk of cannibalism due to size. Large-scale water changes are suspended for 24 hours before and after the grading operation; only bottom sludge removal is performed. The grading requirements are as follows: First grading stage (35-40 days after hatching): When the seedlings reach a total length of approximately 2.0cm, they are screened according to their total length. Seedlings with a total length ≥2.0cm are transferred to a rearing unit mainly fed with formulated feed, while seedlings with a total length <2.0cm are reared separately and continue to be supplemented with live / mixed feed. After grading, the difference in total length of seedlings within the same rearing unit should be ≤±20%. Second grading stage (approximately 60 days after hatching): When the seedlings are approximately 3.0~5.0cm in total length, they are divided into a 5.0~6.0cm specification group and a ≥6.0cm specification group for separate cultivation. After grading, the difference in total length of seedlings within the same cultivation unit is ≤±15%.

[0048] Phased transition of feed Based on the seedling growth and development stages, a smooth transition from live feed to fully formulated feed is gradually achieved. Different particle sizes of formulated feed are used, and the feeding method is small, frequent feedings. The specific feeding plan is as follows: Days 0-20 after hatching (initiation and early rearing stage): Feed rotifers to meet the seedlings' feeding needs and improve early survival rate; 20-35 days after hatching (mixed feed transition stage): Feed artemisia nauplii and 200-300μm microencapsulated compound feed, gradually transitioning the ratio of live feed to compound feed from mainly live feed to 50% each; 35-40 days after hatching (critical stage of feed conversion): Feed Artemia nauplii with 200-300μm formulated feed. For seedlings with a total length ≥2.0cm, gradually reduce the proportion of live feed and switch to formulated feed as the main food source. For seedlings with a total length <2.0cm, delay the feed conversion. After 40 days of incubation (completely formulated feed stage): Feed with a complete formulated feed, with 300-400μm formulated feed from 40 to 60 days, and 400-700μm formulated feed after 60 days.

[0049] Integrated Prevention and Control of Seedling Diseases During the seedling cultivation of silver pomfret, in order to reduce the risk of pathogen growth and improve the seedling survival rate, disease control facilities are configured in the seedling system, and necessary drug control measures are implemented to reduce the incidence of seedling diseases. Specific measures are as follows: Physical control: The seedling cultivation pond is equipped with an ultraviolet sterilization device to continuously sterilize the water. The power configuration is 30W / ton of water, which is used to reduce the basic load of bacteria and parasites in the water. During the seedling stage, dissolved oxygen levels in the water are maintained through microporous aeration or equivalent oxygenation methods, with dissolved oxygen controlled at ≥6.5mg / L, in order to reduce stress response and the risk of secondary infection caused by hypoxia. Large-scale water changes should be suspended within 24 hours before and after seedling grading, and only necessary bottom cleaning should be performed to avoid the cumulative effect of water quality fluctuations on seedling immunity. Routine preventative control: Add Bacillus subtilis or compound Bacillus preparation to the seedling water weekly, at a dosage of 1 mL / m³, with an effective viable bacteria concentration ≥1×10⁻⁶. 8 CFU / mL, regulates the microecological structure of water bodies and inhibits the reproduction of harmful bacteria; Targeted prevention and control of bacterial diseases: When seedlings show signs of bacterial enteritis such as decreased feed intake and abdominal swelling, use florfenicol or similar aquatic antibacterial drugs mixed with feed and feed them at a dosage of 5-10 mg / kg of feed for 3-5 consecutive days. During the medication period, the daily water change should be controlled at 15%-20%, and water quality management should be strengthened to avoid drug residues and water quality deterioration.

[0050] Product Specification Seedling Determination After the above cultivation, seedlings that meet all of the following conditions are determined to be commercial-grade silver pomfret seedlings: the cultivation time is more than 60 days after hatching, the total length is ≥3.0~5.0cm, the weight is ≥1.5g, the total length difference within the same cultivation unit is ≤20%, and the body surface is intact, the swimming posture is normal, and the feeding response is sensitive.

[0051] Example 5: Overwintering pretreatment of commercially available seedlings This embodiment involves pre-treating commercial-grade silver pomfret seedlings cultivated in autumn to enhance their low-temperature tolerance and disease resistance, ensuring successful overwintering and market availability around the time of the fishing ban the following year. The specific procedures are as follows: The commercially available fry obtained in Example 4 were further cultivated in the nursery pond. The water temperature in the nursery pond was gradually reduced to 15-18℃ at a rate of 1℃ / day, and the water quality was kept stable throughout the process. The core water quality parameters were maintained as follows: dissolved oxygen ≥6.0mg / L, salinity 20-30‰, total ammonia nitrogen ≤0.2mg / L, and nitrite ≤0.01mg / L. After the water temperature stabilized, the fry were fed a high-protein compound feed of 400-700μm (crude protein content ≥50% (dry basis), total DHA+EPA ≥1.8%, taurine content ≥0.8%), which was fed quantitatively at 1%-2% of the fry's body weight to strengthen the fry's physique and improve their overwintering low-temperature tolerance and disease resistance. The silver pomfret fry pretreated in this example had an overwintering survival rate of over 85%. After overwintering, the fry were robust and could be directly transferred to the culture pond for adult fish culture or supplied to the market as fry.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for the breeding of silver pomfret (Pampus argenteus) suitable for autumn environment, characterized in that, Includes the following steps: Step 1: Parent Selection Select artificially bred F1 or F2 generation silver pomfret as parent fish, with females weighing ≥150g and males weighing ≥100g, and a male-to-female ratio of 1:1 to 1:1.5; if wild parent fish are used, they must be domesticated and observed for more than 3 months before use, and health screening of parent fish must be carried out to remove parent fish carrying pathogens and those that are unhealthy. Step 2: Parental Enhancement Breeding For the qualified parent stock in step 1, implement refined and enhanced management of feed, light, temperature and water quality. Stabilize the water temperature at 18~20℃ and maintain it for 50~60 days. Feed high-protein mixed feed, control the light intensity at 100~500 lux, change the water volume at 20%~25% per day, maintain dissolved oxygen ≥6.0mg / L, and monitor gonadal development until stage 5 maturity. Step 3: Induction of ovulation and fertilization After the female fish showed signs of natural spawning, the water temperature was maintained at 18-19℃ for about 2 weeks to induce mass spawning of the parent fish. The fertilized eggs were then incubated in a medium-strong light environment with a water temperature of 20.0℃±0.5℃, dissolved oxygen ≥6.5mg / L, and salinity of 20‰-30‰. This resulted in each 150g female fish laying approximately 10,000 eggs at a time, with a fertilization rate ≥75% and a hatching rate ≥80%. Step 4: Seedling cultivation The hatched fry from step 3 are transferred to a nursery pond, where the temperature is gradually increased to 22℃±1.5℃ at a rate of 0.5℃ / day. The basic growth environment is maintained with dissolved oxygen ≥6.5mg / L and salinity 20‰~30‰. Then, the fish are graded and fed in stages according to their growth cycle. At the same time, disease control is carried out during the seedling stage. Finally, commercial seedlings with a total length ≥3.0~5.0cm, a weight ≥1.5g, and a total length difference ≤20% within the same breeding unit are cultivated. Step 5: Overwintering pretreatment of commercially available seedlings The water temperature in the seedling pond was gradually reduced to 15-18℃ at a rate of 1℃ / day to maintain stable water quality. The seedlings were then fed 400-700μm high-protein compound feed to enhance their physical condition and improve their overwintering adaptability.

2. A method for the rearing of silver pomfret (Pampus argenteus) fingerlings suitable for autumnal environment as claimed in claim 1, wherein: In step 1, the parent organisms undergo pathogen detection and health screening. The detection targets include individuals of iridovirus, mermaid bioluminescent bacteria, neuronecrosis virus, dactyloides, amylodinium, cryptocaryon, and ciliates. The parent organisms must have intact bodies with tightly packed scales, no swelling, hemorrhage, or necrosis of internal organs, and bright red gills without abnormal mucus or parasites.

3. A method for the rearing of silver pomfret (Pampus argenteus) fingerlings suitable for autumnal environment as claimed in claim 1, wherein the said method comprises of the steps of: The mixed feed in step 2 is composed of shrimp paste: fish meat: compound feed in a mass ratio of 3:2:5, wherein the crude protein content of the compound feed is ≥50% (dry basis), the total DHA+EPA content is ≥1.8%, and the taurine content is ≥0.8%.

4. The method for the artificial propagation of the silver pomfret in the autumnal environment as claimed in claim 1, wherein: The illumination control in step 2 is divided into two stages: Gonadal development promotion period: photoperiod of 15 hours of light: 9 hours of darkness, light intensity of 500±50 lux; Spawning induction period: photocycle of 8 hours of light: 16 hours of darkness, light intensity of 200±30 lux.

5. A method for the rearing of silver pomfret as claimed in claim 1, wherein the said method is characterized by: The water quality control parameters in step 2 are as follows: Dissolved oxygen: maintained in the range of ≥6.0 mg / L, preferably 6.5~7.5 mg / L; pH value: Controlled range of 7.8~8.6, daily fluctuation ≤0.3; When pH < 7.8, add an appropriate amount of sodium bicarbonate to adjust; when pH > 8.6, reduce excessive algae growth and avoid alkali poisoning. Use an online pH monitor for real-time monitoring to prevent osmotic stress caused by drastic fluctuations; Ammonia nitrogen: Total ammonia nitrogen ≤ 0.2 mg / L, non-ionized ammonia ≤ 0.02 mg / L; When the ammonia level exceeds the standard, measures such as changing the water (10% to 20% of the water volume per change), adding nitrifying bacteria preparations or activated carbon adsorption should be taken to prevent ammonia poisoning from inhibiting feeding and gonadal development. Nitrite: ≤0.01 mg / L; When the concentration is >0.01mg / L, immediately stop feeding high-protein feed, increase the frequency of water changes, and add compound nitrifying bacteria to promote the conversion of nitrite to nitrate; Salinity: maintained within the range of 20-30‰, with daily fluctuations ≤ ±2‰.

6. A method for the rearing of silver pomfret as claimed in claim 1, wherein the said method is characterized by: In step 2, temperature control is achieved through precise temperature control using an air-source heat pump, with the activation threshold being: Heating mode: Starts when the water temperature drops to 17.5~17.7℃; Cooling mode: Starts when the water temperature reaches 20.4~20.6℃; Emergency procedures: If the water temperature does not return to the target range for 2 consecutive hours, manually intervene to adjust the water flow or change the water.

7. The method for raising silver pomfret seedlings suitable for autumn environments according to claim 1, characterized in that: The incubation conditions for the fertilized eggs in step 3 are: water temperature 20.0±0.5℃, dissolved oxygen ≥6.5mg / L, salinity 20~30‰, and medium to strong light environment.

8. A method for raising silver pomfret seedlings suitable for autumn environments according to claim 1, characterized in that: The seedling cultivation stage in step 4 includes the following grading stages: First grading stage: 35-40 days after hatching, seedlings are screened according to their total length. Seedlings with a total length ≥ 2.0 cm are transferred to a rearing unit mainly fed with formulated feed, while seedlings with a total length < 2.0 cm are reared separately and supplemented with live / mixed feed. After grading, the difference in total length of seedlings within the same rearing unit should be ≤ ± 20%. Second grading stage: Approximately 60 days after hatching, the animals are graded and cultivated according to their total length of 5.0~6.0cm and ≥6.0cm, with the total length difference controlled to ≤±15%.

9. A method for raising silver pomfret seedlings suitable for autumn environments according to claim 1, characterized in that: The feed transition stage during the seedling cultivation period is as follows: Days 0-20 after hatching: Feed rotifers; 20-35 days after hatching: Feed with Artemia nauplii and microencapsulated formulated feed with a particle size of 200-300μm, gradually transitioning the ratio of live bait to formulated feed to 50% each; 35-40 days after hatching: Gradually reduce live feed for seedlings with a total length ≥2.0cm and switch to formulated feed as the main source of feed; After 40 days of incubation: feed fully formulated feed; the feed particle size gradient from 40 to 60 days is 300 to 400 μm, and the feed particle size gradient after 60 days is 400 to 700 μm.

10. A method for raising silver pomfret seedlings suitable for autumn environments according to claim 1, characterized in that: The seedling cultivation stage is also equipped with disease control facilities, including: Ultraviolet sterilization device: 30W / ton of water; Probiotic addition: Add 1 mL / m³ of Bacillus subtilis or compound Bacillus subtilis weekly, with an effective live bacteria concentration ≥ CFU / mL; Drug prevention and control: When bacterial enteritis occurs, mix florfenicol with feed and administer 5-10 mg / kg of feed for 3-5 consecutive days; During medication, the daily water change should be controlled at 15% to 20%; large-scale water changes should be suspended within 24 hours before and after seedling grading, and only bottom sludge suction and cleaning should be carried out.

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