A method for inducing rainbow trout to reproduce throughout the season under factory-like recirculating water conditions

Abstract

The present application belongs to the technical field of artificial breeding of rainbow trout, and particularly relates to a method for inducing full-season breeding of rainbow trout under the condition of factory circulating water. 3 The method for inducing full-season breeding of rainbow trout under the condition of factory circulating water is characterized in that rainbow trout parent fish is put into a factory circulating water breeding system at a density of not more than 35 kg / m The water quality and flow rate, water temperature, illumination and nutrition are controlled during the breeding process. The present application precisely matches the gonadal development rhythm of parent fish through multiple environmental parameters, strictly controls the core indicators of breeding, the maturation rate of female gonads is greater than or equal to 97%, the average egg production of single female is stably maintained at 8000 to 12000, the average fertilization rate of artificial insemination is higher than 92%, and the fish egg malformation rate is controlled within 3%. The present application realizes full-season breeding of rainbow trout and improves the quality of fish eggs and sperm.

Description

Technical Field

[0001] This invention belongs to the field of rainbow trout artificial breeding technology, specifically relating to a method for inducing rainbow trout to reproduce all seasons under factory-scale recirculating water conditions. Background Technology

[0002] Rainbow trout are high-quality cold-water aquaculture fish, prized for their tender flesh, rich nutrition, and high economic value. The industry has a solid foundation for promotion and a broad market prospect. Currently, rainbow trout farmed in my country are mainly divided into two categories: ordinary diploid rainbow trout and high-quality all-female diploid rainbow trout.

[0003] In traditional rainbow trout farming, the water temperature for broodstock should be maintained at no higher than 17℃ year-round. Feeding should be intensified during the critical gonadal development period in August and September. The breeding season for broodstock is in winter and early spring, with water temperatures between 6℃ and 13℃. Feeding should be gradually reduced two months before spawning, and stopped 2-3 days before spawning. When the broodstock mature, artificial fertilization and hatching are performed. Traditional rainbow trout farming can only complete broodstock breeding during the low-temperature window of winter and early spring. This fixed breeding window and concentrated fry supply make it impossible to achieve continuous and balanced fry production year-round, which is insufficient to meet the continuous fry supply demands of modern aquaculture. Furthermore, traditional rainbow trout farming can only meet the basic gonadal growth needs of females, not the breeding needs of pseudo-males. Pseudo-males obtained through artificial sex reversal have unique physiological structures and lack the ability to ejaculate spontaneously. Artificial fertilization requires dissection to obtain sperm and prepare seminal plasma. Pseudo-male sperm exhibit uneven maturity, low sperm motility, and insufficient fertilization stability, resulting in poor sperm and egg quality.

[0004] Therefore, existing rainbow trout breeding techniques suffer from a fixed breeding window and poor sperm and egg quality. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for inducing rainbow trout to reproduce year-round under factory-scale recirculating water conditions.

[0006] The purpose of this invention is to provide a method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions, comprising the following steps: Rainbow trout broodstock were fed at a rate not exceeding 35 kg / m 3 The stocking density was introduced into a factory-style recirculating aquaculture system. The fish were cultured in 28-31 day cycles, with each cycle consisting of 9 cycles. Fish eggs and sperm were obtained in the 8th and 9th cycles of each cycle.

[0007] The aquaculture process includes water quality and flow rate regulation, water temperature regulation, light regulation, and nutrient regulation.

[0008] The water quality control refers to controlling the total ammonia nitrogen in the water body to be <0.2 mg / L, the non-ionic ammonia to be <0.02 mg / L, and the pH to be 7.2~7.8.

[0009] The water temperature control refers to controlling the water temperature to be between 6℃ and 13℃, with daily water temperature fluctuations ≤1℃.

[0010] The light control refers to the lighting period starting from 5:30 to 8:30 AM daily, with the light intensity reaching its maximum from 1:00 to 1:30 PM, and the lighting duration being 10 to 15 hours. The increase and decrease in light intensity are uniform. The maximum light intensity is 2000 lx.

[0011] The water flow control refers to maintaining a stable water flow of 50m during daily aquaculture. 3 / h~70m 3 During the spawning induction phase, the flow rate is gradually increased to 90m / h daily at set times. 3 / h~120m 3 / h, and continue for 1h.

[0012] Preferably, the nutritional control refers to controlling the crude fat content in the feed to 5%~8%, the crude protein content to 45%~50%, and the astaxanthin content to 60ppm~80ppm. Feeding is performed once daily at 12-hour intervals.

[0013] Preferably, the male-to-female ratio of the rainbow trout parent fish is 4-10:1.

[0014] Preferably, the rainbow trout broodstock weigh between 2.5 kg and 3.5 kg per fish. The male rainbow trout broodstock are selected from pseudo-males aged 2.5 to 3 years. The female rainbow trout broodstock are selected from fully female diploids aged 3 to 4 years. This sex-to-male gamete development ratio ensures high reproductive efficiency.

[0015] Preferably, the water quality control method includes the following steps: The ammonia nitrogen content and pH value of the aquaculture water are tested at 10:00 and 22:00 daily to maintain the pH value of the water in the range of 7.2 to 7.8.

[0016] Change the water 3 times a day, with each water change being no less than 10% of the total water volume of the circulating water system. During the water change process, the water temperature difference should not exceed 1°C to prevent rainbow trout from experiencing stress.

[0017] Clean the aquaculture system every 7 days, removing uneaten feed, feces, and other organic waste to reduce ammonia nitrogen accumulation in the water caused by organic matter decomposition. Add nitrifying bacteria to the aquaculture water every 15 days at a dosage of 0.5 g / m³. 3 Through the biodegradation of microorganisms, the accumulation of ammonia nitrogen in water bodies is effectively reduced, and water quality is maintained.

[0018] Preferably, the precise pH control method is as follows: when the water pH < 7.6, adjust the pH at 10 g / m³. 3Sodium bicarbonate is added to adjust the alkalinity; when the water pH is > 8.0, the dosage is 5 g / m³. 3 Citric acid was added to adjust the pH level, and the pH value of the water was monitored every 30 minutes during the pH adjustment process until the water quality parameters returned to the standard range.

[0019] Preferably, the flow rate regulation adopts a phased differentiated control: maintaining a water flow of 58m under normal aquaculture conditions. 3 / h~62m 3 / h, ensuring a stable aquatic environment for aquaculture. The water flow is precisely increased to 90m at 11:00 daily. 3 / h~100m 3 The constant flow stimulation is applied for 1 hour, and the physical stimulation formed by the flow rate difference is used to activate the gonadal activity of female fish, induce the development and maturation of eggs, and lay the foundation for ovulation.

[0020] Preferably, a gradual temperature change is used between adjacent aquaculture periods to achieve stable temperature control, with an adjustment period of 3 to 5 days. The water temperature control during each period is as follows:

[0021] The first stage, with a water temperature of 13℃, ensures the recovery of the rainbow trout broodstock's physical strength and body growth and development, maintaining a good physical condition. The second stage, with a water temperature of 12℃, allows the broodstock to gradually adapt to the low-temperature aquaculture environment, avoiding low-temperature stress damage. The third stage, with a water temperature of 11℃, initiates the maturation and development of the broodstock's gonads, simultaneously activating the developmental activity of the female's ovary and the pseudo-male's seminal vesicle. The fourth stage, with a water temperature of 10℃, continues to promote the growth and maturation of the ovary and seminal vesicle. The fifth stage, with a water temperature of 9℃, accelerates the development and expansion of the female's ovary, simultaneously promoting the proliferation and development of the pseudo-male's seminal vesicle. The sixth stage, with a water temperature of 8℃, promotes the full development and accumulation of nutrients in the female's eggs, pushing the pseudo-male's sperm into the maturation stage. The seventh stage, with a water temperature of 7℃, maintains the homeostasis of the female's egg maturation, stabilizes the physiological metabolism of the pseudo-male's seminal vesicle, and maintains a high sperm motility reserve. The eighth stage, with a water temperature of 6℃, completes the physiological preparation for ovulation in the female, inducing mature eggs to detach from the ovarian tissue and fully disperse and solidify, while simultaneously completing the final maturation and solidification of the pseudo-male's sperm, maximizing sperm motility. The water temperature in the 9th stage is 7℃ to ensure that the female fish can ovulate smoothly and to maintain the high activity of sperm in the testes of the pseudo-male fish, which is suitable for subsequent dissection and sperm collection and seminal plasma preparation processes, ensuring efficient artificial fertilization of sperm and eggs.

[0022] Preferably, the entire water temperature is precisely controlled through the RAS factory-scale circulating water temperature control system.

[0023] Preferably, the duration of illumination in each phase of the illumination regulation process is as follows: Phase 1: 15 hours of light to adapt to the parent fish's environmental acclimatization needs. Phase 2: 14 hours of light to continue adapting to the light environment. Phase 3: 13 hours of light to initiate gonadal development. Phase 4: 12 hours of light to continuously promote ovarian and seminal vesicle growth and development. Phase 5: 11 hours of light to accelerate egg and sperm development. Phase 6: 10 hours of light to maintain stable gamete development. Phase 7: 9 hours of light to stabilize sperm and egg maturation. Phase 8: 9 hours of light to complete pre-ovulation physiological preparation, ensuring successful egg release and maintaining sperm motility. Phase 9: 10 hours of light to ensure normal ovulation in female fish, maintain sperm cell activity, and facilitate dissection for sperm collection, seminal plasma preparation, and artificial insemination.

[0024] Preferably, the method for nutritional regulation includes the following steps: Rainbow trout broodstock are fed in small amounts frequently at 8:00 AM and 8:00 PM daily. The feeding status of the broodstock is monitored in real time. When the feeding activity of the broodstock decreases or the proportion of uneaten food in the aquaculture water exceeds 10%, the amount of food given at each feeding is reduced to avoid excessive feed spoiling the water quality.

[0025] Match the feed particle size to the body length of the broodstock. For broodstock with a body length of 30cm to 50cm, use formulated feed with a particle size of 4mm to 6mm. For broodstock with a body length greater than 50cm, use formulated feed with a particle size of 6mm to 8mm.

[0026] During the breeding process, rainbow trout-specific compound vitamins were added to the feed for 7 consecutive days every 20 days, with the amount of vitamins added being 0.1% of the total weight of the feed on that day.

[0027] By strengthening nutrition in stages and matching the full-cycle glandular gradient development rhythm, the eggs of female fish and the sperm of pseudo-male fish are matured in an orderly manner, stabilizing the physiological activity of gametes and meeting the needs of breeding processes.

[0028] Preferably, the daily feeding amount of the broodstock is strictly controlled at 2‰ to 5‰ of their body weight. This feeding amount can precisely adapt to the stage-specific developmental needs under the control of water temperature and light gradients, and match the nutritional consumption of the gradual development of eggs and the maturation of seminal vesicles. This ensures the steady development of gonads and maintains high gamete activity, while avoiding the problems of organic matter accumulation, water quality deterioration, and stress on broodstock caused by overfeeding, thus ensuring the long-term stable operation of the recirculating aquaculture system.

[0029] Compared with the prior art, the present invention has the following significant advantages: 1. The method of inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture systems of this invention utilizes precise and coordinated multi-dimensional gradient control of water temperature, light, water flow, water quality, and nutrients to artificially reconstruct the year-round developmental environment of rainbow trout gonads, completely breaking the inherent limitations of traditional autumn and winter seasonal breeding of rainbow trout and achieving year-round breeding. This invention precisely matches the gonadal development rhythm of parent fish with multiple environmental parameters, strictly controls core aquaculture indicators, achieving a female gonadal maturity rate ≥97%, a stable average egg production of 8000-12000 eggs per female, an average artificial insemination fertilization rate higher than 92%, and controlling the egg deformity rate to within 3%, resulting in high egg and sperm quality. Therefore, the method of inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture systems of this invention not only achieves year-round breeding of rainbow trout but also improves the quality of eggs and sperm.

[0030] The method of inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture systems according to the present invention includes the following steps: feeding rainbow trout broodstock at a rate not exceeding 35 kg / m³ 3 The stocking density was introduced into a factory-style recirculating aquaculture system. The fish were cultured in 28-31 day cycles, with each cycle consisting of 9 cycles. Fish eggs and sperm were obtained in the 8th and 9th cycles of each cycle.

[0031] The aquaculture process includes water quality control, water flow control, water temperature control, light control, and nutrient control. These five dimensions are synergistically regulated to disrupt the natural reproductive rhythm of rainbow trout and achieve stable breeding throughout the year. Water quality control refers to maintaining total ammonia nitrogen <0.2 mg / L, non-ionized ammonia <0.02 mg / L, and pH between 7.2 and 7.8 to ensure stress-free growth and development of the broodstock. Water temperature control refers to maintaining the water temperature between 6℃ and 13℃, with daily temperature fluctuations ≤1℃. During the maturation stage, the water temperature is precisely controlled within the range of 6℃ to 10℃ to meet the needs of gonadal maturation. Light control refers to providing light from 5:30 to 8:30 AM daily, reaching maximum intensity between 1:00 and 1:30 PM, with a duration of 10-15 hours. Increases and decreases in light intensity are uniform. The maximum light intensity is 2000 lx. To avoid stress on the parent fish caused by sudden changes in light intensity, the duration of light is controlled in each stage of the breeding cycle using a gradient reduction followed by fine-tuning to match the gamete development rhythm. Water flow control refers to maintaining a stable water flow of 50 m³ / h during daily aquaculture. 3 / h~70m 3 / h, ensuring uniform dissolved oxygen and water quality in the water body. During the spawning induction phase, the flow rate is gradually increased to 90m³ / h at set times each day. 3 / h~120m 3 / h, and continue for 1h, to activate the gonads of the parent fish through physical stimulation of water flow.

[0032] 2. This invention targets the breeding system of all-female diploid rainbow trout, specifically matching the physiological specificities of artificially sex-reversed pseudo-males. Unlike traditional diploid rainbow trout breeding techniques, it simultaneously considers the gradient maturation of female eggs and the development of pseudo-male testes and sperm activation. Addressing the process characteristics of pseudo-males being unable to ejaculate spontaneously and requiring dissection to collect sperm for pulping, it precisely controls environmental and nutritional parameters in the later stages of breeding, stably locking in high sperm activity. This solves the core problems of asynchronous sperm and egg development, poor sperm quality, and low fertilization rates in existing technologies, and is compatible with domestically produced all-female triploid rainbow trout breeding processes.

[0033] 3. This invention employs a nine-stage gradual temperature and light gradient control mode, coupled with a refined water quality, water flow, and nutrient management system, to avoid stress responses in broodstock caused by sudden environmental changes, significantly reducing the incidence of diseases in broodstock. By strictly matching the appropriate water temperature range, light rhythm, water flow stimulation, water quality threshold, and specific nutrient ratio for gonad development, a complete physiological regulation chain is formed, from broodstock physical recovery, gonad activation, gamete development to mature ovulation and sperm retrieval. This results in excellent synchronicity of male and female gamete development and uniform and stable sperm and egg quality, reducing egg deformity rates from the source and significantly improving artificial insemination rates and seedling survival rates. Simultaneously, leveraging the advantages of recirculating aquaculture, precise feeding control effectively reduces the accumulation of organic matter in the water, lowers the risk of water quality deterioration, and achieves intensive, green, and sustainable all-season breeding production, fully meeting the needs of modern aquaculture's large-scale and standardized development. Detailed Implementation

[0034] To enable those skilled in the art to clearly understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to preferred embodiments. 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 implementation methods obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0035] Unless otherwise stated, all technical terms used in this invention are for the purpose of defining the embodiments only and do not constitute a limitation on the scope of protection of this invention. The raw materials, reagents, and equipment used in this embodiment can all be purchased commercially or prepared using existing technologies.

[0036] The main materials used in this invention are special compound feed for rainbow trout broodstock and rainbow trout compound vitamins.

[0037] The rainbow trout broodstock-specific formulated feed was purchased from Aile Aquatic Products (Qingdao) Co., Ltd., model name Ailebaoshuo, trade name Aile. The rainbow trout-specific compound vitamins were purchased from Sanbei Salmon and Trout Fishery Technology Development Co., Ltd.

[0038] The rainbow trout broodstock selected for this invention were robust, free from injury or disease, and of uniform size. Robustness was defined as a condition rating of 1.2–1.7. Uniform size meant that the weight, body length, and condition rating of the experimental individuals were similar. The broodstock weight was controlled at 2.5 kg / fish to 3.5 kg / fish, and the seedlings were purchased from AquaSearch in Denmark. Male individuals were 2.5–3 years old artificially sex-reversed pseudo-male adults, and female individuals were 3–4 years old all-female diploid sexually mature individuals.

[0039] The complete recirculating aquaculture system used in this invention is model MBBR-RAS-SM-10×202, a modular cold-water recirculating aquaculture system for salmon and trout developed by Billund Aquaculture of Denmark. The system comprises 10 culture tanks, each 4m long, 4m wide, and 1.3m deep, with an effective water volume of 20.2m³. 3 The total designed aquaculture water volume is 120m. 3 ~240m 3 .

[0040] The specific configuration of individual equipment in the factory-scale recirculating aquaculture system is as follows: The filtration unit is equipped with a Hydrotech HDF1606 microfilter and a Grundfos CR5-16 microfilter backwash pump. The water circulation unit is equipped with three Grundfos NB125-250 / 232 return water pumps, a GMPB3KQ-A backwash pump, and a Grundfos NB32-180 / 2 drain pump. The biological filter backwash unit is equipped with a Vacuvane VSC03152ST551-7 blower and four Sodeca Neolineo 315 blower-tricks. The water disinfection unit has two water paths, each equipped with an Ultraaqua Monoray 4-440SS oxygenated water UV sterilizer and an Ultraaqua Monoray 10-440SS oxygen-free water UV sterilizer. The water booster pump set is equipped with two Grundfos NB80-200 / 214 oxygenated water pressure pumps and two Grundfos NB125-200 / 196-172 anaerobic water pressure pumps. The system uses a biofilm method as its core water treatment process, combined with electrical automation control and online water quality monitoring technology, to achieve water recycling. It can control key environmental indicators such as water temperature, pH, and dissolved oxygen throughout the entire process, providing energy-efficient and closed-loop aquaculture conditions for land-based cold-water fish farming.

[0041] Example 1 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: One hundred all-female diploid female fish were placed in a factory-style recirculating aquaculture system and cultured in one natural month as one period, with each full breeding cycle consisting of nine periods. Fish eggs were obtained in the eighth and ninth periods of each cycle.

[0042] The aquaculture process includes water quality and flow rate control, water temperature control, light control, and nutrient control. The specific process is as follows:

[0043] 1. Water quality and flow rate regulation Stable water quality is fundamental to ensuring the normal growth, gonadal development, and successful spawning of broodstock. Ammonia nitrogen levels and pH values ​​in the aquaculture water are tested twice daily, at 10:00 AM and 10:00 PM. Water is changed three times daily, with each change replacing at least 10% of the total system water volume. The water temperature difference during water changes is strictly controlled to be ≤1℃ to avoid stress on the broodstock. Uneaten food, feces, and other organic waste are removed from the tank bottom weekly to reduce ammonia nitrogen accumulation caused by organic matter decomposition. Nitrifying bacteria are added to the water every 15 days at a dosage of 0.5 g / m³ to reduce ammonia nitrogen levels through microbial degradation.

[0044] The aquaculture tank is maintained at a water flow rate of 60m / s daily. 3 / h. The water flow will be increased to 95m daily at 11:00 AM. 3 / h, continuous constant flow stimulation for 1h, induces gonad activation in parent fish and promotes spawning through physical stimulation of water flow.

[0045] 2. Water temperature control The factory-scale recirculating aquaculture system of this invention is equipped with temperature control equipment, with a temperature control range of 5℃~17℃. It features a water temperature sensor with an accuracy of ±0.1℃ and integrates with an IoT system to monitor water temperature and dissolved oxygen in real time, strictly controlling daily water temperature fluctuations to ≤1℃. Water temperature regulation is implemented with gradient changes based on the gonadal development patterns of rainbow trout. The transition adjustment period between adjacent rearing cycles is controlled within 3~5 days to ensure that the broodstock gradually adapt to the environmental temperature and avoid sudden temperature changes affecting egg development and migration. Detailed water temperature parameters and control objectives for each cycle are shown in Table 1.

[0046] Table 1. Water temperature parameters and control objectives for each cultivation cycle. 3. Light control 100W LED supplemental lighting specifically designed for rainbow trout farming was used. The LED supplemental lighting was installed at a height of 1.67m, with one light per farming unit to ensure uniform light intensity distribution and a maximum light intensity of 2000 lx. The entire lighting control system, relying on an IoT system, controlled the light intensity according to the lighting time and duration specified in Table 2, uniformly increasing it from 0 lx to 2000 lx and then uniformly decreasing it back to 0 lx. This simulated the physiological changes in natural light, characterized by "gradual increase from weak to strong, stable maintenance, and orderly gradual change," thereby precisely inducing and regulating the gonadal development and sexual maturation of rainbow trout. Details of the lighting duration and control objectives for each cycle are shown in Table 2.

[0047] Table 2. Illumination duration and control objectives for each cultivation cycle. 4. Nutritional regulation Nutritional regulation is the core element for ensuring normal gonadal development in broodstock and supporting year-round breeding. This program focuses on the nutritional needs of female gonadal development, precisely controlling feed nutrient indicators and feeding procedures to meet the nutritional requirements for gamete growth while avoiding nutritional imbalances, uneaten feed spoiling water quality, and other problems.

[0048] Use mold-free, fresh, specially formulated feed for broodstock, matching the feed particle size according to the broodstock's body length: broodstock 30cm in length are fed with 4mm particle size feed; broodstock 40cm in length are fed with 5mm particle size feed; and broodstock 50cm in length are fed with 6mm particle size feed. Feed at 8:00 AM and 8:00 PM daily, with a daily feed amount of 3‰ of the broodstock's body weight, using a small, frequent feeding method. Observe the broodstock's feeding status in real time; when feeding activity decreases or uneaten feed exceeds 10% of the water, adjust the feed amount accordingly. The feed nutritional indicators, supplementation plan, and control targets are shown in Table 3.

[0049] Table 3 Feed Nutritional Indicators and Feeding Control Plan Crude fat content 8% Fish oil and vegetable oil are selected as the fat raw materials; animal fat is prohibited. The fat content of the feed is sampled every 15 days to ensure that the indicators meet the standards. To avoid the parent fish becoming excessively obese and compressing the gonads, thus reducing ovulation disorders. crude protein content 48% The protein raw materials used are fish meal, soybean meal, and silkworm pupa powder to ensure a balanced amino acid profile; protein content is tested every 10 days. Meets the growth needs of eggs and gonadal tissues, and reduces the metabolic burden on organs. Astaxanthin addition amount 60ppm Natural astaxanthin with a purity of ≥95% is selected and mixed evenly with the feed; each batch of feed is sampled and tested. Improves oocyte free-floating properties, enhances oocyte quality and fertilization rate, and reduces the proportion of abnormal oocytes. Routine feeding management Feed twice a day, at a rate of 3‰ of body weight. Feed should be scattered and distributed at fixed times, and any uneaten feed should be removed 1 hour after feeding. The feed should be stored in a cool, dry place for no more than 30 days. Improve nutrient absorption rate and prevent feed spoilage and water pollution from uneaten feed. Fortified supplements Add once every 20 days, at a rate of 0.1% of the total feed weight. Feed rainbow trout-specific multivitamins to supplement vitamins A, E, and D. Promotes the development of gonads and fish eggs, and enhances the immunity of parent fish. Example 2 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: The daily water flow rate in the aquaculture tank in Example 1 was adjusted to 50 m / s. 3 / h, the water flow is adjusted to 90m at 11:00 every day. 3 The daily feeding rate was adjusted to 2‰ of the broodstock's body weight. The crude fat content in the feed nutritional indicators was adjusted to 5%, and the crude protein content to 45%. All other conditions remained the same as in Example 1, and fish eggs were obtained.

[0050] Example 3 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: The daily water flow rate in the aquaculture tank in Example 1 was adjusted to 70 m / s. 3 / h, the water flow is adjusted to 100m at 11:00 every day. 3 The daily feeding rate was adjusted to 5‰ of the broodstock's body weight. The crude fat content in the feed nutritional indicators was adjusted to 10%, and the crude protein content to 50%. All other conditions remained the same as in Example 1, and fish eggs were obtained.

[0051] The all-female diploid female fish cultured in Examples 1-3 exhibited low stress levels during the rearing period, showed no outbreaks of disease, and demonstrated excellent growth, with a stable condition of 1.2-1.7 in body fat percentage, indicating good basic conditions for gonadal development. Under standardized cycle control, the all-female diploid female fish showed high synchronicity in gonadal development and concentrated maturation. The gonadal maturity rate of the all-female diploid female fish reached over 97%, with an average spawning volume of 8,000-12,000 eggs per female.

[0052] Example 4 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: In Example 1, 100 all-female diploid female fish were replaced with 100 sex-reversed pseudo-male adult fish, while the other conditions remained the same as in Example 1, and sperm was obtained.

[0053] Sex-reversed pseudo-males exhibit uniform gonadal development and stable semen quality, making them suitable for artificial insemination. The average fertilization success rate is over 92%, and the egg deformity rate is controlled below 3%. The resulting fertilized eggs develop synchronously and exhibit batch-to-batch uniformity in quality.

[0054] Example 5 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: The factory-style recirculating aquaculture system in Example 1 was replaced with a system that was 8m long, 2.5m wide, and 1.7m deep, while keeping all other conditions the same as in Example 1, and fish eggs were obtained.

[0055] Example 6 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: The factory-style recirculating aquaculture system in Example 4 was replaced with a system that was 8m long, 2.5m wide, and 1.7m deep, while keeping all other conditions the same as in Example 4, and sperm was obtained.

[0056] The effects of Examples 5 and 6 were similar to those of Examples 1 to 4. During the broodstock rearing period, the stress level was low, no outbreaks of disease occurred, and the fish exhibited excellent growth, with a stable condition of 1.2-1.7. Gonadal development was regular, and batch synchronization was excellent. The broodstock reached maturity in a concentrated period, with the gonadal maturity rate of females reaching over 97%. The average spawning volume per female remained stable at 8,000-12,000 eggs, the average fertilization rate of artificial insemination was higher than 92%, and the egg deformity rate was consistently controlled below 3%.

[0057] The breeding process of this invention has strong environmental adaptability and a wide range of operational tolerance. It is compatible with factory-style recirculating aquaculture systems of different water bodies and supporting equipment. Fertilized eggs develop synchronously and the quality of each batch is uniform. It can stably achieve continuous large-scale breeding of rainbow trout throughout the year and has excellent industrial promotion value and versatility.

[0058] Comparative Example 1 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: The water temperature control method in Comparative Example 1 was adjusted to: using natural water temperature combined with a simple constant temperature mode, with water temperature changes entirely dependent on the external environment and no active, refined control methods. The overall rearing water temperature was maintained at 13℃, and the water temperature was controlled below 12℃ for 6 months before spawning. The 9-stage gradient temperature change process of this invention was not implemented, nor was the requirement of daily water temperature fluctuation ≤1℃ enforced, making it easy for diurnal and seasonal temperature differences to exceed the limits. A slow adaptation transition period of 3-5 days was not set for the transition between different water temperature ranges, which could easily cause environmental stress in the parent fish. The entire temperature control method only passively follows the natural reproductive rhythm of rainbow trout and cannot implement targeted temperature control according to different developmental stages of the gonads. It can only achieve routine breeding in autumn and winter and does not have the ability to breed in all seasons.

[0059] Comparative Example 2 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: The lighting control method in Comparative Example 1 was adjusted to use natural light combined with conventional lighting facilities. The lighting duration was fixed at a constant 12-hour light / 12-hour dark cycle throughout the rearing period, without adjusting the daytime duration in accordance with the gradient of gonadal development. Lighting fixtures were directly turned on and off without a buffer period of at least 30 minutes between gradual brightening and dimming; sudden changes in light intensity easily disrupted the endocrine homeostasis of the parent fish. Lighting was only considered a basic environmental condition and was not linked to the timing of control measures such as water temperature and water flow, resulting in asynchronous gonadal development within the group.

[0060] Comparative Example 3 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: The nutritional control method in Comparative Example 1 was adjusted as follows: Ordinary adult rainbow trout feed was used, with a crude protein content of 43% and a crude fat content of 20%. No 60 ppm astaxanthin or rainbow trout-specific multivitamins or other functional nutrients were added, and no special feed formula tailored to the gonadal development of the broodstock was provided. The feeding method employed traditional, timed, and quantitative extensive management, with a daily feed amount of 2% of the broodstock's body weight and a fixed amount per feeding throughout the entire period. The method of frequent small feedings was not adopted, nor was the feed amount dynamically adjusted based on the broodstock's feeding status and the percentage of uneaten food in the water. Nutritional supply only met the basic growth needs of the broodstock and could not specifically improve egg quality and fertilization rate.

[0061] Comparative Example 4 A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions includes the following steps: The water quality and flow rate control methods in Comparative Example 1 were adjusted to traditional aquaculture standards, with the water pH maintained at 7.5 and the total ammonia nitrogen limit set at ≤1.0 mg / L. Daily monitoring of ammonia nitrogen and pH was not conducted; water quality was maintained primarily through regular water changes, manual cleaning, and the water body's self-purification process. Nitrifying bacteria were not added periodically to optimize the aquatic microecology, and water temperature differences were not strictly controlled during water changes. A constant flow rate of 40 m / s was maintained throughout the process. 3 The system lacks a daily scheduled high-flow physical spawning induction process. The water flow only performs basic functions such as water exchange and oxygenation, and is not incorporated into the reproductive control system, resulting in dispersed and poorly synchronized spawning of parent fish.

[0062] Comparative Example 1 relied entirely on the natural changes in water temperature in the external environment, without any phased gradient cooling acclimatization or refined periodic temperature control. The other cultivation conditions were consistent with those of the experimental group. The ovarian development of the parent fish was basically stopped at stage II-III, the gonadal maturity rate was less than 2%, the average number of eggs laid by a single female fish was only 500-2000, the average fertilization rate was 52%, and the fish egg malformation rate reached 18%.

[0063] Comparative Example 2 used conventional 100W LED lighting fixtures, without the specialized supplemental lighting equipment used in Example 1, and lacked precise light intensity control of 800lx~2000lx. Throughout the rearing process, a constant light-dark cycle of 12 hours of light and 12 hours of darkness per day was employed, without adjusting the daytime duration according to the gonadal development process. The lighting fixtures were directly started and stopped without a gradual brightening and dimming buffer mechanism. The gonadal maturity rate of female fish was only 42%, with no effect on early spawning; some parent fish experienced a 10-12 day delay in spawning; the average fertilization rate was 55%; and the egg deformity rate was 10%.

[0064] Comparative Example 3 was fed with ordinary adult rainbow trout feed without the addition of functional nutrients or a special formula for broodstock. The broodstock were deviating from the appropriate range in terms of fatness, with an overall high level and large individual differences. The gonadal maturity rate of female fish was only about 50%, the average number of eggs laid by a single female fish was about 3,000, and the egg deformity rate reached 12%.

[0065] Comparative Example 4 adopted traditional factory-style aquaculture standards for water quality and flow control, maintaining a pH of 7.5 and a total ammonia nitrogen limit of ≤1.0 mg / L. It did not conduct twice-daily fixed-point and quantitative monitoring of ammonia nitrogen and pH, relying solely on regular water changes, manual cleaning, and the water body's self-purification to maintain water quality. It did not periodically add nitrifying bacteria to optimize the aquatic microecology, and the water temperature difference during water changes was not strictly controlled. The entire process used a 40m... 3 A constant water flow of / h was maintained, without a daily scheduled high-flow physical spawning induction process. The water flow only served the basic functions of water exchange and oxygenation, and was not incorporated into the reproductive control system. Other cultivation conditions remained consistent with the experimental group. The spawning of parent fish was scattered and extremely synchronic, with insufficient uniformity in gonad development. The gonadal maturity rate of female fish was only 58%, the proportion of individuals spawning in concentrated areas was low, the average fertilization rate was 56%, and the egg deformity rate was 11%.

[0066] The results of Examples 1-6 and Comparative Examples 1-4 indicate that the synergistic regulation of multiple factors such as water temperature, light, water quality, and nutrients can effectively break the natural seasonal reproductive limitations of rainbow trout, achieving stable breeding throughout the year. It can significantly improve the gonadal maturity rate, spawning volume, and fertilization rate of broodstock, greatly reduce the rate of egg deformities, and simultaneously reduce environmental stress and disease occurrence.

[0067] Conclusion Existing research on artificial breeding of rainbow trout is mostly focused on natural flow-through aquaculture models, and most studies only explore the impact of light duration on the breeding cycle. A complete technical system for the coordinated regulation of multiple factors such as water temperature, water flow, ammonia nitrogen, pH, dissolved oxygen, light, and nutrients has not yet been formed.

[0068] This invention innovatively constructs a multi-dimensional parameter synergistic control system: water temperature is stably controlled between 6℃ and 13℃, with 6℃ to 10℃ being the gonadal maturation-promoting range. Water flow conditions, ammonia nitrogen content, pH value, and dissolved oxygen are strictly controlled. Combined with a gradually brightening and dimming light mode of 800lx to 2000lx, and a customized nutrient ratio, this completely solves the technical bottleneck of concentrated breeding seasons and the inability to achieve year-round large-scale breeding due to the constraints of water temperature and light rhythms in natural environments, enabling stable year-round breeding of rainbow trout under factory-style recirculating water conditions.

[0069] It should be noted that the numerical range described in this invention includes the two endpoints of the interval and any intermediate value within the interval. Those skilled in the art can make appropriate modifications and variations to the embodiments based on the inventive concept of this invention, and such modifications and variations all fall within the protection scope of this invention. This specification only describes the invention in conjunction with preferred embodiments and is not intended to limit the invention. All equivalent substitutions and improvements made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture systems, characterized in that, Includes the following steps: Rainbow trout broodstock were fed at a rate not exceeding 35 kg / m 3 The stocking density is put into the factory-style recirculating aquaculture system; the stocking is carried out in 28-31 day periods, with each 9 periods constituting a complete breeding cycle. Fish eggs and sperm are obtained in the 8th and 9th periods of each cycle. The aquaculture process includes water quality and flow rate regulation, water temperature regulation, light regulation, and nutrient regulation. The water quality control refers to controlling the total ammonia nitrogen in the water body to be <0.2 mg / L, the non-ionic ammonia to be <0.02 mg / L, and the pH to be 7.2~7.8; The water temperature control refers to controlling the water temperature to be between 6℃ and 13℃, with daily water temperature fluctuations ≤1℃. The light control refers to the lighting starting from 5:30 to 8:30 every day, with the light intensity reaching its maximum from 13:00 to 13:30, and the lighting duration being 10 to 15 hours. The increase and decrease in light intensity are uniform. The maximum light intensity is 2000 lx. The water flow control refers to maintaining a stable water flow of 50m during daily aquaculture. 3 / h~70m 3 During the spawning induction phase, the flow rate is gradually increased to 90m / h daily at set times. 3 / h~120m 3 / h, and continue for 1h.

2. The method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions according to claim 1, characterized in that, The nutritional control refers to controlling the crude fat content in the feed to 5%~8%, the crude protein content to 45%~50%, and the astaxanthin content to 60ppm~80ppm.

3. The method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions according to claim 1, characterized in that, The rainbow trout broodstock weighed between 2.5 kg and 3.5 kg per fish; the male rainbow trout broodstock were selected from pseudo-males aged 2.5 to 3 years; the female rainbow trout broodstock were selected from fully female diploids aged 3 to 4 years.

4. The method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions according to claim 1, characterized in that, The water quality control method includes the following steps: The ammonia nitrogen content and pH value of the aquaculture water are tested at 10:00 and 22:00 daily to maintain the pH value of the water in the range of 7.2 to 7.

8. Change the water 3 times a day, with each water change volume not less than 10% of the total water volume of the circulating water system, and the water temperature difference during the water change process not exceeding 1℃. Organic waste in the aquaculture system should be removed every 7 days; nitrifying bacteria should be added to the aquaculture water every 15 days at a dosage of 0.5 g / m³. 3 .

5. A method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions according to claim 4, characterized in that, The precise pH control method is as follows: when the water pH < 7.6, adjust the pH by 10 g / m³. 3 Sodium bicarbonate is added to adjust the alkalinity; when the water pH is > 8.0, the dosage is 5 g / m³. 3 Citric acid was added to adjust the pH level, and the pH value of the water was monitored every 30 minutes during the pH adjustment process until the water quality parameters returned to the standard range.

6. The method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions according to claim 1, characterized in that, The method for regulating flow rate includes the following steps: The aquarium is maintained at a water flow rate of 58m / s daily. 3 / h~62m 3 / h; the system water flow will be increased to 90m at 11:00 every day. 3 / h~100m 3 The flow rate is maintained at a constant current for 1 hour, and the physical stimulation of the water flow rate difference induces the activation of the female fish's gonads and promotes spawning.

7. The method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions according to claim 1, characterized in that, During the water temperature regulation process, the water temperature regulation at each stage is as follows: The water temperature in the first stage was 13℃; the water temperature in the second stage was 12℃; the water temperature in the third stage was 11℃; the water temperature in the fourth stage was 10℃; the water temperature in the fifth stage was 9℃; the water temperature in the sixth stage was 8℃; the water temperature in the seventh stage was 7℃; the water temperature in the eighth stage was 6℃; and the water temperature in the ninth stage was 7℃.

8. The method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions according to claim 1, characterized in that, During the illumination regulation process, the illumination duration for each period is as follows: The illumination duration for the first phase was 15 hours; for the second phase, it was 14 hours; for the third phase, it was 13 hours; for the fourth phase, it was 12 hours; for the fifth phase, it was 11 hours; for the sixth phase, it was 10 hours; for the seventh phase, it was 9 hours; for the eighth phase, it was 9 hours; and for the ninth phase, it was 10 hours.

9. The method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions according to claim 1, characterized in that, The method of nutritional regulation includes the following steps: Rainbow trout broodstock are fed in small amounts and frequently at 8:00 and 20:00 daily. The feeding status of the broodstock is monitored in real time. When the feeding activity of the broodstock decreases and the proportion of uneaten feed in the aquaculture water exceeds 10%, the amount of feed per feeding is reduced to avoid excessive feed spoiling the water quality. Match the feed particle size to the body length of the broodstock. For broodstock with a body length of 30cm to 50cm, use a feed with a particle size of 4mm to 6mm; for broodstock with a body length of more than 50cm, use a feed with a particle size of 6mm to 8mm. During the breeding process, rainbow trout-specific compound vitamins were added to the feed for 7 consecutive days every 20 days, with the amount of vitamins added being 0.1% of the total weight of the feed on that day.

10. The method for inducing rainbow trout to reproduce year-round under factory-scale recirculating aquaculture conditions according to claim 1, characterized in that, The daily feeding amount for the parent fish is 2‰ to 5‰ of their body weight.

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