Macrobrachium rosenbergii two-year staggered breeding method

Abstract

The application relates to the technical field of aquaculture, and particularly discloses a one-year two-cycle staggered breeding method for Macrobrachium rosenbergii. The method sets two breeding cycles in sequence, constructs a coordinated operation system of a marker pond and a breeding pond, realizes high-yield breeding through a two-stage marker process, greenhouse temperature control breeding in stages and a batch-by-batch staggered fishing strategy, and the first cycle is to breed marker fish in a greenhouse in winter and spring and sell the marker fish in May-July, and the second cycle is to breed marker fish in summer, keep warm in late autumn and sell the marker fish in October-November, so that the concentrated selling low-price interval can be accurately avoided. The application can significantly improve the breeding yield per unit area, improve the survival rate of seedlings and resource utilization rate, reduce disease loss, and balance economic and ecological benefits, and is suitable for large-scale breeding popularization.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, specifically to a method for staggered farming of giant freshwater prawns twice a year. Background Technology

[0002] The market demand for giant freshwater prawns is stable, and large-scale farming is widespread. Currently, the mainstream industry model is the traditional single-crop farming model, with highly concentrated stocking and market entry times. The peak market entry in July and August each year leads to a significant price drop, 30% to 40% lower than off-season prices. Farmers generally experience bumper harvests but low profits, with an average net profit of only 3,000 to 5,000 yuan per mu. Furthermore, the traditional model employs extensive seedling cultivation methods, often directly releasing juvenile prawns or using simple first-grade seedlings. Pond cleaning and water disinfection are not standardized, resulting in low seedling survival rates. In addition, the lack of water quality control, uneaten feed and excrement easily cause excessive levels of harmful substances in the water, leading to frequent disease outbreaks. Moreover, there are no unified standards for farming management; seedling ponds and rearing ponds operate independently, resulting in low utilization rates of facilities and water and soil resources.

[0003] To address these issues, the industry has been exploring double-cropping technology for giant freshwater prawns, extending the farming cycle through greenhouses and increasing total yield through seasonal farming. However, the existing double-cropping technology still suffers from unreasonable farming cycle planning. The timing of harvesting and marketing adult prawns fails to precisely avoid the low-price range in the market, making it impossible to realize the off-peak premium benefits of double-cropping farming. In addition, the investment in greenhouse facilities, multiple batches of seedlings, and operation and maintenance keeps the overall cost high. Summary of the Invention

[0004] To develop a new farming model for giant freshwater prawns, this invention provides a method for staggered farming of giant freshwater prawns twice a year.

[0005] The present invention adopts the following technical solution: A method for staggered farming of giant freshwater prawns with two crops a year is characterized by setting up two farming cycles of first and second crop farming in succession throughout the year, and constructing a coordinated operation system of seedling ponds and farming ponds. Through two-level seedling technology, greenhouse temperature-controlled farming, and staggered harvesting strategy, high-yield staggered farming is achieved. The first batch of shrimp farming started winter and spring greenhouse seedling cultivation in late November of the first year, and the mature shrimp that had been cultivated were transferred to the farming pond in March of the second year. They were harvested and marketed in batches from May to July of the second year. The second batch of shrimp farming begins in mid-May of the following year with the cultivation of summer seedlings. From late July to early August of the following year, the mature shrimp that have been cultivated are transferred to the first batch of cleaned farming ponds, and water quality is controlled during the high-temperature period. From early October of the following year, the farming cycle is extended by using greenhouses for insulation. The shrimp are harvested and marketed in batches from mid-October to mid-November of the following year.

[0006] This invention significantly improves aquaculture profitability through a synergistic strategy of "two harvests per year" and "staggered shrimp harvesting." Both harvests precisely target peak market periods, increasing yield per acre by over 50% compared to traditional single-crop harvesting. Staggered harvesting further ensures higher quality shrimp for premium pricing. The coordinated operation of nursery ponds and aquaculture ponds, combined with "two-stage nursery" and greenhouse control technology, enhances seedling survival and resource utilization while reducing unit yield consumption. Standardized management and ecological control measures throughout the entire process effectively suppress diseases, reducing disease losses by 10%–20% while minimizing environmental impact. Balancing economic and ecological benefits, the operational guidelines are clear, adaptable to various aquaculture scales, and easy to implement.

[0007] Furthermore, the two-stage seedling process is divided into two stages: primary seedling and secondary seedling. Primary seedling involves introducing juvenile giant freshwater prawns with a size of 0.9-1.0 cm and feeding them with giant freshwater prawn microencapsulated feed for cultivation. When the juvenile prawns grow to 2.0-2.5 cm, they are transferred to the secondary seedling stage and fed with juvenile shrimp formulated feed to cultivate them into qualified shrimp seedlings with a size of 3-4 cm.

[0008] Furthermore, the first two-stage seedling cultivation is carried out in a seedling pond covered with a double-layer heat-insulating film, and the seedling pond is divided into a mother pond and a daughter pond; The first-stage seedlings are raised in the mother pond at a stocking density of 600,000 to 1,000,000 fish per acre, with the water temperature controlled at 24℃ to 28℃, dissolved oxygen at 5 mg / L to 7 mg / L, and pH at 7.2 to 8.4. Secondary seedlings are raised in sub-ponds, with a daily feeding amount of 4% to 6% of the total shrimp body weight, a weekly water exchange of 20% to 30%, and a water pH of 7.2 to 8.4.

[0009] Furthermore, in the second batch of two-stage seedlings, the initial daily feed intake for the first-stage seedlings was 90-110 g / 10,000 shrimp, and the daily feed intake increased by 10% as the shrimp grew.

[0010] Furthermore, the daily feed intake for secondary-level seedlings is 340-420 g / 10,000 fish.

[0011] Furthermore, the water body management during the high-temperature period is as follows: the aerator is turned on for 8 to 10 hours a day, the water is changed 1 to 3 times a week, and the water volume changed each time is 20% to 30% of the total water volume. When the water temperature exceeds 30°C, cooling control is implemented, and the pH value of the water body is maintained at 7.2 to 8.4.

[0012] Furthermore, the first batch of adult shrimp farming was carried out in aquaculture ponds covered with a single layer of heat-insulating film, with a shrimp fry stocking density of 40,000 to 50,000 shrimp per acre.

[0013] Furthermore, during the greenhouse temperature-controlled breeding stage, the water temperature inside the greenhouse is controlled at 20℃~24℃, the water pH value is 7.2~8.6, the dissolved oxygen is 5 mg / L~7 mg / L, and the weekly water exchange rate is 15%~25%.

[0014] Furthermore, staggered harvesting in batches is implemented using ground cage nets to catch larger shrimp while leaving smaller ones. The first batch of shrimp is harvested in mid-May of the following year, with adult shrimp weighing 25-30 g / tail harvested, and adult shrimp weighing 30-35 g / tail harvested in mid-June of the following year. The second batch of shrimp is harvested in mid-to-late October of the following year, with adult shrimp weighing ≥30 g / tail harvested, and pond clearing and harvesting completed in early to mid-November of the following year.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves this through precise planning of a two-crop farming cycle throughout the year, coupled with a staggered harvesting strategy of "catching the large and leaving the small" to avoid peak periods. The first crop is harvested from May to July, and the second from October to November. Both harvesting periods avoid the low-price range of concentrated market supply, precisely targeting the high-price period. Actual testing has verified that the average selling price of mature shrimp is more than 56% higher than the traditional single-crop model, fully capturing market price benefits. The two-crop farming model combined with coordinated pond operation significantly improves the output efficiency per unit area. Implementation data shows that, despite reducing the farming area by 33 mu compared to the traditional model, the total output value is still 276,500 yuan higher; the total net profit reaches 1,768,200 yuan, an increase of 870,400 yuan compared to the traditional model; and the average annual net profit per mu reaches 23,615 yuan, an increase of 249.85% compared to the traditional single-crop model, demonstrating a significant increase in revenue. Staggered harvesting and market supply according to shrimp size ensures uniform shrimp size and stable quality, meeting the market's demand for high-quality products and further realizing a quality premium.

[0016] This invention constructs a collaborative operation system for nursery ponds and aquaculture ponds, allowing for the continuous reuse of ponds and greenhouse facilities throughout the two-crop cycle. This breaks the resource idleness problem inherent in the independent operation of nursery and aquaculture in traditional models, significantly improving the comprehensive utilization efficiency of land, facilities, and water resources. A graded cultivation system of "first-level nursery + second-level nursery" is established, matching corresponding feed types, feeding strategies, and water environment parameters to different growth stages of larvae. This cultivates qualified shrimp larvae with uniform size, strong vitality, and excellent stress resistance, improving larval survival rate and stable aquaculture production from the source. Differentiated greenhouse management schemes are adopted for different aquaculture stages in winter / spring, high temperatures, and late autumn—double-layer insulation film is used in winter / spring to achieve early nursery, cooling control is implemented during high-temperature periods, and insulation film is used in late autumn to extend the aquaculture cycle, overcoming the limitations of natural water temperature on the aquaculture cycle and ensuring a smooth transition between the two crops per year.

[0017] This aquaculture method forms a quantifiable and implementable operational standard for the entire process, covering all aspects from pond cleaning and disinfection, two-stage seedling cultivation, adult shrimp rearing, water quality monitoring, disease prevention and control, to harvesting and marketing. All control parameters are clearly defined, the operational boundaries are clear, it is highly replicable, can be adapted to aquaculture entities of different sizes, and is easy to promote and implement on a large scale and in a standardized manner. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the process of farming giant freshwater prawns twice a year. Detailed Implementation

[0020] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific 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. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0021] Example 1: A method for staggered farming of giant freshwater prawns twice a year.

[0022] This embodiment was carried out at the Yangsong Joint Giant Freshwater Prawn Farm in Xiaoshan District, Hangzhou City, covering an area of ​​100 mu (approximately 6.7 hectares). This includes 20 mu (approximately 1.3 hectares) of nursery ponds (10 mu (approximately 1.6 hectares) for offspring and 10 mu (approximately 1.6 hectares) for mother prawns, using double-layered insulated film greenhouses), and 80 mu (approximately 5.3 hectares) of rearing ponds (single-layered insulated film greenhouses). The entire process strictly adhered to core technical procedures such as coordinated operation of nursery and rearing ponds, precise temperature and light control in greenhouses, ecological water quality optimization, and staggered harvesting. The process flow for the double-cropping of Giant Freshwater Prawns in this invention is as follows: Figure 1 Throughout the year, two independent yet closely integrated seedling and rearing systems were established. The first crop relied on winter and spring greenhouse insulation for early seedling cultivation and staggered harvesting; the second crop continued with summer seedling cultivation and late autumn insulation to delay market launch. Through cyclical and refined management, the system effectively avoided the industry's peak market downturn and significantly improved the economic benefits of aquaculture.

[0023] I. Management of the First Standard Seedling Pond (Late November - February) 1. Pond cleaning and drying (late November to mid-December) Drain the pond water and remove uneaten feed, organic debris, aquatic plant roots and stems, and excessive silt from the bottom, leaving a 12±2 cm cultivated layer. After leveling the pond bottom, dry the pond and expose it to the sun for 20±5 days until the bottom cracks, oxidizing and decomposing the organic matter in the bottom mud, reducing the viral load of Decapoda iridovirus (DIV1) in the bottom mud, and simultaneously inactivating pathogenic bacteria such as Vibrio and fungi, as well as wild fish, snails, and overwintering insect eggs, thus reducing the virus transmission vector.

[0024] 2. Water disinfection and basic feed cultivation (mid-December) The inlet is equipped with a 90±10 mesh double-layer silk screen filter, and the inlet depth is 0.7±0.1 m; quicklime is sprinkled on the whole pond at 100±10 kg / mu for disinfection, and left to stand for 4±1 days until the toxicity disappears.

[0025] Apply 200±50 kg / mu of well-rotted organic fertilizer to cultivate basic food such as rotifers and cladocerans. After 4±1 days, test the water transparency. When the transparency reaches 35±5 cm, prepare to release the seedlings.

[0026] 3. Two-stage seedling cultivation (late December - February) 3.1 Grade 1 seedlings (late December to mid-January) In nursery ponds covered with double-layer insulation film (10 mu of mother pond nursery stock), stock juvenile giant freshwater prawns ("Shufeng No. 1") measuring 0.9±0.1 cm were introduced at a stocking density of 80±200,000 prawns / mu. Giant freshwater prawn microencapsulated feed (Yancheng Haida Biological Feed Co., Ltd.) was provided 3 to 4 times daily, with feeding completed within 1 to 2 hours. Water temperature was controlled at 26±2℃, dissolved oxygen at 6±1 mg / L, and pH 7.2≤8.4 (pH in nursery water is prone to rise; upper limit control is crucial). A 0.5 kW impeller aerator was installed per mu.

[0027] 3.2 Second-level seedlings (late January - February) When the juvenile shrimp reach a length of 2.5 ± 0.5 cm, approximately half of them are transferred to a 10-mu (approximately 6.7 hectares) nursery pond for secondary nursery training. They are fed with formulated juvenile shrimp feed (Yancheng Haida Biological Feed Co., Ltd.) with a particle size of 1.0 mm to 1.5 mm, at a daily feeding rate of 5 ± 1% of the total shrimp body weight, divided into two feedings, one in the morning and one in the evening. The water is changed once a week, with a water exchange volume of 25 ± 5%, maintaining the water pH at 7.2 ≤ pH ≤ 8.4.

[0028] II. Management of the First Breeding Pond (Late November - July) 1. Pond cleaning, drying, and sun-drying (late November to late January) Drain the pond water, remove uneaten feed, organic debris, aquatic plant residue and excessive silt from the bottom of the pond, and retain a 12±2 cm cultivated layer; dry the pond for 30±5 days, and turn over the bottom of the pond once every 10 days to inactivate benthic pathogens and harmful organisms.

[0029] 2. Water intake, disinfection, and fertilization (late January - February) The inlet is fitted with a 70±10 mesh silk screen filter, with an inlet depth of 1.1±0.1 m. Quicklime is applied to the entire pond at 100±10 kg / mu for disinfection, and the solution is left to stand for 7 days. EM bacterial solution (Hubei Fengtian Biotechnology Co., Ltd.) is added at 2±0.2 kg / mu (effective viable bacteria count ≥5×10⁻⁶). 11 After regulating the microecology with CFU / catties, apply 250±50 kg / mu of well-rotted organic fertilizer 3 days later to cultivate plankton and build the initial aquaculture ecosystem.

[0030] 3. Seedling distribution (early to mid-March) Select healthy shrimp larvae that are 3.5±0.5 cm in size, vigorous, and free from injury or disease. One day before transplanting, add 7±2 cm of fresh water to both the nursery pond and the rearing pond, adjusting the water temperature (≤2℃), salinity (≤2‰), and pH (≤0.3) to be as consistent as possible. Stock the rearing pond at a density of 45,000 shrimp per acre, distributing them evenly from multiple points.

[0031] 4. Temperature-controlled greenhouse farming (late March - April) A single-layer insulated, fully enclosed greenhouse is used to control the water temperature inside at 22±2℃, with pH 7.2≤8.6. When the air temperature is ≥20℃, the side ventilation openings are opened for air exchange, and shade nets are added to lower the temperature during the midday sun. 2.0 mm particle size formulated feed (Yancheng Haida Biological Feed Co., Ltd.) is fed 2 to 3 times daily, with feeding completed within 1 to 2 hours. A 1 kW impeller aerator is installed per acre to maintain dissolved oxygen at 6±1 mg / L. The water is changed once a week, with a replacement volume of 20±5%, maintaining a water transparency of 40±5 cm.

[0032] 5. Staggered fishing season (May-July) The shrimp were harvested in three stages using a "catch the big, leave the small" strategy with ground nets. In mid-May, shrimp weighing 25-30 g / tail were harvested; in mid-June, shrimp weighing 30-35 g / tail were harvested; and in mid-July, the remaining shrimp were harvested after the pond was cleared. After each harvest, 12±2 cm of fresh water was added. After the second harvest, 0.3 kg / mu of chlorine dioxide was sprayed throughout the pond for disinfection. Two days later, 1±0.2 kg / mu of EM (Effective Live Bacteria) solution (≥5×10⁻⁶) was applied. 11 Adjust water quality using CFU / catties.

[0033] III. Management of the Second Stage Seedling Pond (Mid-May to Early August) To reduce workload, breeding risks and costs, the breeding area for the second crop will be reduced to 48 mu.

[0034] 1. Pond pretreatment (mid-May to mid-June) After all the shrimp larvae from the first batch have been transferred out, pond cleaning operations should be carried out immediately. Uneaten feed, dead shrimp, and weeds should be removed from the pond bottom, leaving a 12±2 cm cultivated layer. After draining the pond, the water should be exposed to sunlight for 6±1 days. Water should then be added to a depth of 0.7±0.1 m, and 0.3 kg / mu of chlorine dioxide should be sprayed throughout the pond for disinfection. After settling for 3 days, 200±50 kg / mu of well-rotted organic fertilizer should be applied to cultivate basic food organisms such as rotifers and cladocerans.

[0035] 2. Two-stage seedling cultivation (mid-May to mid-July) Giant freshwater prawn larvae measuring 1.0 ± 0.2 cm were introduced using a two-stage seedling raising process: Grade 1 seedlings: Stocking density 70±100,000 shrimp / acre, fed with macrophage microencapsulated feed, sprinkled throughout the pond 4 times a day (06:30, 10:30, 14:30, 18:30), initially 100±10 g / 10,000 shrimp per day, increasing by 10% daily as the larvae grow; Second-level seedlings: When the juvenile shrimp reach a size of 2.0 cm, they are transferred to the second-level cultivation and fed with juvenile shrimp formulated feed, which is given 3 times a day (07:00, 14:00, 18:30), with a daily feed amount of 380±40 g / 10,000 shrimp.

[0036] High-temperature control: run the aerator for 9±1 hours daily; change the water twice a week, with each water change being 25±5% of the total water volume; maintain the water temperature at 7.2≤pH≤8.4 and the transparency at 35±5 cm; when the water temperature exceeds 30℃, cool it down by adding fresh water or covering it with a shade net.

[0037] 3. Seedling preparation (late July - early August) When the shrimp larvae grow to a size of 3.5±0.5 cm, the nursery stage is completed. One day before the transplanting, the water temperature (≤2℃), salinity (≤2‰), and pH value (≤0.3) of the nursery pond and the rearing pond are adjusted to be consistent to reduce the stress response of the larvae; weak, injured, and diseased individuals are manually screened to ensure that the shrimp larvae entering the pond are of uniform size and have good vitality.

[0038] IV. Management of the Second Aquaculture Pond (August-November) 1. Seedling distribution (late July to early August) Immediately after the first batch of aquaculture is completed, the ponds should be cleaned up. Diseased and dead shrimp and uneaten feed from the bottom of the pond should be removed to prevent the spread of iridovirus through the remains. Fishing nets and water pumps for each pond should be used separately and disinfected regularly. Then, the ponds should be cleaned up again to remove excess silt and retain a 12±2 cm topsoil layer. The pond water should be drained and exposed to the sun for 4±1 days. The water should be filled to a depth of 1.3±0.1 m, and 100 kg / mu of quicklime should be sprinkled on the entire pond for disinfection. After standing for 5 days, 200 kg / mu of well-rotted organic fertilizer should be applied to cultivate plankton.

[0039] The shrimp fry were released in early August at a density of 48,000 fry per mu (approximately 0.16 acres). Healthy shrimp fry of uniform size and good vitality were selected and released evenly at multiple locations.

[0040] 2. High-temperature cultivation management (mid-August to September) 2.1 Water quality control The aerator is turned on for 14±2 hours daily to maintain dissolved oxygen in the water at 6±1 mg / L; the water is changed 2 to 3 times a week, with each water change accounting for 35±5% of the total water volume. The water change is carried out in the early morning or evening.

[0041] Apply EM bacterial solution (Hubei Fengtian Biotechnology Co., Ltd.) at a rate of 1 ± 0.2 kg / mu (effective live bacteria count ≥ 5 × 10⁻⁶) to the entire pond every 10 days. 11 The water quality is regulated using CFU / catties, which controls the aquatic microecology and nitrogen-phosphorus balance. pH (7.2 ≤ pH ≤ 8.4), dissolved oxygen (6 ± 1 mg / L), ammonia nitrogen, and nitrite are monitored weekly, with ammonia nitrogen ≤ 0.5 mg / L and nitrite ≤ 0.1 mg / L.

[0042] 2.2 Feeding Management Feed the shrimp with a compound feed containing 3.5±0.5 mm particles and 35±5% crude protein, twice a day, between 6:00 and 7:00 AM and between 6:00 and 7:00 PM. The evening feeding should account for 65±5% of the total daily feeding, and the daily feeding rate should be 5±1% of the total body weight. Check the feed tray for uneaten feed 1-2 hours after feeding and adjust the total feeding amount for the next day accordingly.

[0043] 3. Greenhouse-heated aquaculture (starting from early October) In early October, a full-coverage greenhouse was constructed, with the sides compacted and sealed, and ventilation openings were left. The water temperature inside the greenhouse was controlled at 20±2℃. When the air temperature was below 15℃, the ventilation openings were closed to retain heat, and ventilation was opened when the temperature rose at noon.

[0044] 4. Staggered fishing in batches (mid-October to mid-November) The shrimp were harvested in two stages using a "catch the big, leave the small" strategy with gill nets: adult shrimp (≥30 g / tail) were harvested in mid-to-late October; the second harvest was completed in early to mid-November, followed by pond clearing. After each harvest, 12±2 cm of fresh water was added, and EM (Effective Microorganisms) solution (Hubei Fengtian Biotechnology Co., Ltd.) at 1±0.2 kg / mu (effective live bacteria count ≥5×10⁻⁶) was applied. 11 CFU / catties) to regulate water quality.

[0045] V. Daily breeding management 1. Water quality monitoring Daily monitoring of water temperature, pH, and dissolved oxygen; weekly monitoring of ammonia nitrogen, nitrite, and transparency; establishment of water quality monitoring records; and timely adjustment of water quality control measures based on monitoring results.

[0046] 2. Disease prevention and control Adhering to the principle of "prevention first, combined with treatment," regular preventative disinfection of the aquaculture water is carried out: A 10% aquatic-specific povidone-iodine solution is diluted 400±100 times with water and applied to the entire pond, once or twice a month; the dosage is 300±100 mL per mu (approximately 0.067 hectares) with a water depth of 1 m, and the effective iodine working concentration in the water is 0.45 to 0.75 mg / L. Application should be done on sunny mornings, and is prohibited in low-oxygen environments. EM compound bacterial solution can be applied only after a 48-hour interval to avoid the disinfectant killing beneficial microorganisms in the water. For daily feeding, a basic formulated feed for adult giant freshwater prawns is used, with an immune enhancer (to improve the prawns' stress resistance and disease resistance) added to the basic feed. The immune enhancer is composed of vitamin C, astragalus polysaccharide, and β-glucan, with a total addition of 1.2±0.2 kg / t of feed. The mass ratio of the compound components is vitamin C: astragalus polysaccharide: β-glucan = 3:2:2 (w:w:w). Check the feed tray for uneaten feed 1 to 2 hours after each feeding, and adjust the total amount of feed for the next day based on the amount of uneaten feed remaining.

[0047] 3. Regular inspections Inspect the breeding ponds and seedling ponds twice a day, once in the morning and once in the evening, to check the feeding and activity of the shrimp fry, check the operation of facilities such as aerators and greenhouses, and promptly clean up weeds and uneaten feed in the ponds to prevent the invasion of harmful organisms.

[0048] 4. Record Management Establish complete aquaculture records, including detailed information on the release time, quantity, and size of seedlings, the type and amount of feed provided, water quality monitoring data, disinfection and medication administration, and the time, quantity, size, and sales of catches, to provide data support for subsequent aquaculture optimization.

[0049] Comparative Example 1: The farming model is a traditional greenhouse early seeding + open-air direct release single-cycle farming. The farming location is Lihai Town, Shangyu District, Shaoxing City, Zhejiang Province (the main farming area of ​​giant freshwater prawns, adjacent to the farming area of ​​this embodiment, with comparable basic farming conditions such as climate, water source, and soil). The main farmers are local large-scale giant freshwater prawn farmers, with a total of 20 farming ponds and a total farming area of ​​133 mu. Among them, 2 ponds, totaling 15 mu, are covered by wire-insulated greenhouses, and the remaining 118 mu are open-air conventional farming ponds without insulation. The farming seedlings used are "Shufeng No. 1" giant freshwater prawn larvae, and the commercial seedling brand is "Guoliang". The complete farming cycle is from February 2025 to November 2025. The core features of this traditional farming model are: the use of a single-crop farming system of greenhouse early seeding combined with open-air direct release, without a two-level grading and seedling cultivation process, without staggered harvesting and staggered high-price market planning, and the concentrated and simultaneous market sales of adult prawns. The specific farming operation process is as follows:

[0050] 1. Pond preparation (December 2024 - January 2025) In early December, all pond water was drained, and weeds, uneaten feed, and floating organic debris were manually removed. After dredging, a 12±2 cm bottom mud layer was retained for cultivation. The pond bottom was left to dry naturally in the open air for 12 days without mechanical tilling or deep sun exposure for detoxification. The inlet was equipped with only a simple 60-mesh single-layer silk sieve for filtration, with a single water depth of 0.7±0.1 m. Conventional disinfection was carried out by spraying quicklime throughout the pond at a dosage of 100 kg / mu. After disinfection, the pond was left to stand for 3 days before organic fertilizer was added. No microbial agents were used for systematic aquatic microecological restoration. The base fertilizer was well-rotted chicken manure that had been composted and rendered harmless for 15 days, with a uniform application dosage of 200±50 kg / mu. During the initial feeding stage of the shrimp larvae, there was no natural food supply, and they relied entirely on artificial formulated feed (Yancheng Haida Biological Feed Co., Ltd.). They were fed 3-4 times a day, with a simple check of uneaten feed 1-2 hours after feeding, without standardized rules for adjusting the amount of uneaten feed.

[0051] 2. Seedling release The early seedling release in the greenhouse was on February 6, 2025, with a total of 6 million juvenile shrimp released into the 15-mu (approximately 1 hectare) wire mesh greenhouse pond. The juvenile shrimp were released directly into the pond without undergoing two-stage seedling raising or grading. The open-air direct release of seedlings took place on May 10, 2025, with approximately 4 million juvenile shrimp released into the 118-mu (approximately 7.5 hectares) open-air aquaculture pond.

[0052] 3. Daily breeding management 3.1 Water Temperature Control In greenhouse ponds, simple mulching is used for insulation from February to April, resulting in large fluctuations in water temperature (exceeding 4℃). In open-air ponds, natural water temperature is used for aquaculture from May to September. There are no cooling measures during the high-temperature period, and no sealing and insulation measures are used after the temperature drops in October, so the aquaculture cycle cannot be extended.

[0053] 3.2 Water Quality Management There is no standardized daily or weekly water quality monitoring mechanism, and no fixed monitoring plan for water temperature, dissolved oxygen, pH, ammonia nitrogen, and nitrite. New water is added irregularly based on water turbidity, with no fixed standard for the amount of water exchanged per cycle. Only a simple 0.3kW impeller aerator is installed per acre in the pond, with no 24 / 7 dissolved oxygen control zone. The water disinfectant used is two common aquatic preparations: quicklime and chlorine dioxide. The microecological preparation used is a commercially available ordinary compound EM bacterial solution, purchased from a local ordinary aquatic agricultural supply store, with no fixed application cycle or fixed dosage per acre.

[0054] 3.3 Feeding The entire process used ordinary compound feed (Yancheng Haida Biological Feed Co., Ltd.), and the feed particle size and protein ratio were not adjusted according to the growth stage; the feeding frequency and amount were not fixed, and timed and quantitative feeding was not implemented, with a feed conversion ratio of 1.43 throughout the process.

[0055] 3.4 Disease Prevention and Control Disease control mainly relies on symptomatic treatment after the onset of disease, without implementing preventive disinfection with povidone-iodine 1-2 times per month; no immune enhancers such as vitamin C, astragalus polysaccharide, and β-glucan are added to the feed throughout the entire process, and there are no routine ecological prevention measures; the seedlings have not undergone graded and standardized seedling cultivation, resulting in weak stress resistance and disease resistance in the shrimp.

[0056] 4. Fishing and marketing Harvesting operations commenced on June 20, 2025, and the entire pond was cleared by November 27, 2025. Harvesting tools included a combination of seine nets and traps, with a phased approach of catching larger prawns and leaving smaller ones. Only a small amount of fresh water was added after each harvest, without disinfection or the application of EM bacteria to improve bottom sediment and water quality. The peak market season for giant freshwater prawns in major production areas is from August to November each year. The vast majority of harvesting and sales fall within this peak season, resulting in saturated market supply and low purchase prices. There were no plans for greenhouse-controlled temperature control to allow for earlier harvesting or staggered harvesting; sales were entirely based on market conditions, making it impossible to capitalize on the high-price gaps from May to July and late November.

[0057] In Example 1 of this invention, two-crop aquaculture was achieved in 100 mu and 48 mu aquaculture ponds respectively, with a total output value of RMB 4.2565 million and a total net profit of RMB 1.7682 million, and an average annual profit of RMB 23,615 per mu.

[0058] The first batch of prawn farming commenced with staggered harvesting on May 18, 2025, and was completed on June 20, 2025, coinciding with a market supply gap during the conventional giant freshwater prawn farming season. The total yield for this batch was 80,000 jin (40,000 kg), with an average selling price of 36 yuan / jin (18 yuan / catties) for adult prawns, generating a total output value of 2.88 million yuan. The total cost of the first batch was 1.672 million yuan, broken down as follows: feed cost 540,000 yuan (feed coefficient 1.3), prawn larvae cost 162,000 yuan, pond rent 260,000 yuan (annual rent amortized), electricity cost 200,000 yuan, animal health insurance cost 80,000 yuan, labor cost 80,000 yuan, and other expenses 350,000 yuan. Calculations show that the net profit for the first batch was 1.208 million yuan, with an average net profit of 12,080 yuan per mu (0.067 hectares), validating the profitability improvement effect of the off-peak farming model.

[0059] The second crop of giant freshwater prawns was harvested in batches starting October 20, 2025, and all harvesting operations were completed by November 30, 2025. This harvesting period coincided with the end of the conventional giant freshwater prawn farming season, when market supply was reduced and prices were high. The farming area for this crop was 48 mu (approximately 3.2 hectares), with 2.3 million prawn larvae stocked, resulting in a total yield of 39,900 jin (approximately 14,650 kg). The average selling price of adult prawns was 34.5 yuan / jin (approximately 16.8 yuan / catties), achieving a total output value of 1.3765 million yuan. The total cost of the second crop was 816,400 yuan, broken down as follows: feed cost 385,700 yuan (feed conversion ratio 1.9), prawn larvae cost 85,100 yuan, pond rent 50,000 yuan (annual rent amortized), electricity cost 72,000 yuan, animal health cost 96,000 yuan, greenhouse construction cost 51,600 yuan, and other expenses 76,000 yuan. The calculated net profit for the second crop was 560,100 yuan, with an average net profit of 11,668 yuan per mu (approximately 12,680 yuan / hectare), maintaining a stable and high level of profitability.

[0060] Comparative Example 1: Total aquaculture area of ​​133 mu (approximately 8.2 hectares), total output of 180,000 jin (approximately 90 tons), and average yield of 1353.38 jin (approximately 67.9 tons) per mu (approximately 72.5 tons per hectare); average selling price of adult shrimp of 22.11 yuan / jin (approximately 11.5 yuan / kg), achieving a total output value of 3.98 million yuan. Total cost: 3.0822 million yuan, detailed as follows: feed cost 1.2384 million yuan (feed coefficient 1.43), shrimp fry cost 348,000 yuan, pond rent 345,800 yuan / year, electricity cost 150,000 yuan, animal health insurance cost 150,000 yuan, labor cost 250,000 yuan, and other expenses 600,000 yuan. Total net profit: 897,800 yuan, and average net profit per mu (approximately 0.067 hectares) of 6,750 yuan.

[0061] Under the same aquaculture area, seedling source, and management level, compared with Comparative Example 1 (133 mu of traditional greenhouse early seedling + open-air direct release aquaculture model), Example 1 of this invention (100 mu of "two crops a year + staggered shrimp harvesting" high-yield aquaculture model) has the following results: the aquaculture area is reduced by 33 mu, but the total output value is still 276,500 yuan higher, and the output efficiency per unit area is significantly improved; the total net profit is 1,768,200 yuan, an increase of 870,400 yuan; the average net profit per mu is 23,615 yuan, an increase of 249.85%; through the staggered market strategy, the average selling price of adult shrimp is increased by more than 56%, solving the industry problem of "bumper harvest but not profitable" caused by the concentrated market in traditional aquaculture; the two-crop-a-year cycle combined with the coordinated operation of seedling ponds and aquaculture ponds greatly improves the efficiency of land, facility and water resource utilization, adapts to the needs of large-scale, standardized and green aquaculture, and the overall economic benefits are significantly better than the traditional model.

[0062] Although preferred embodiments of the invention have been described, those skilled in the art, once they have learned the basic inventive concept, can make other changes and modifications to these embodiments.

[0063] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for staggered farming of giant freshwater prawns twice a year, characterized in that, The system is designed to have two consecutive farming cycles throughout the year: the first and second farming cycles. A coordinated operation system for seedling ponds and aquaculture ponds is also established. Through two-level seedling technology, greenhouse temperature-controlled farming, and staggered harvesting strategies, high-yield aquaculture can be achieved. The first batch of shrimp farming started winter and spring greenhouse seedling cultivation in late November of the first year, and the mature shrimp that had been cultivated were transferred to the farming pond in March of the second year. They were harvested and marketed in batches from May to July of the second year. The second batch of shrimp farming begins in mid-May of the following year with the cultivation of summer seedlings. From late July to early August of the following year, the mature shrimp that have been cultivated are transferred to the first batch of cleaned farming ponds, and water quality is controlled during the high-temperature period. From early October of the following year, the farming cycle is extended by using greenhouses for insulation. The shrimp are harvested and marketed in batches from mid-October to mid-November of the following year.

2. The method for staggered farming of giant freshwater prawns twice a year according to claim 1, characterized in that, The two-stage seedling process is divided into two phases: primary seedling and secondary seedling. Primary seedling involves introducing juvenile giant freshwater prawns (0.9-1.0 cm) and feeding them with microencapsulated feed. When the juveniles grow to 2.0-2.5 cm, they are transferred to the secondary seedling stage and fed with formulated feed to grow into qualified seedlings of 3-4 cm.

3. The method for staggered farming of giant freshwater prawns twice a year according to claim 2, characterized in that, The first two-stage seedling cultivation was carried out in a seedling pond covered with a double-layer heat-insulating film, and the seedling pond was divided into a mother pond and a daughter pond; The first-stage seedlings are raised in the mother pond at a stocking density of 600,000 to 1,000,000 fish per acre, with the water temperature controlled at 24℃ to 28℃, dissolved oxygen at 5 mg / L to 7 mg / L, and pH at 7.2 to 8.

4. Secondary seedlings are raised in sub-ponds, with a daily feeding amount of 4% to 6% of the total shrimp body weight, a weekly water exchange of 20% to 30%, and a water pH of 7.2 to 8.

4.

4. The method for staggered farming of giant freshwater prawns twice a year according to claim 2, characterized in that, In the second crop, the initial daily feed intake for the first-stage juvenile shrimp was 90-110 g / 10,000 shrimp, and the daily feed intake increased by 10% as the shrimp grew.

5. The method for staggered farming of giant freshwater prawns twice a year according to claim 2, characterized in that, The daily feed intake for Grade II seedlings is 340-420 g / 10,000 fish.

6. The method for staggered farming of giant freshwater prawns twice a year according to claim 1, characterized in that, The water management during the high-temperature period is as follows: the aerator is turned on for 8 to 10 hours a day, the water is changed 1 to 3 times a week, and the water volume changed each time is 20% to 30% of the total water volume. When the water temperature exceeds 30℃, cooling control is implemented, and the pH value of the water is maintained at 7.2 to 8.

4.

7. The method for staggered farming of giant freshwater prawns twice a year according to claim 1, characterized in that, The first batch of adult shrimp farming was carried out in aquaculture ponds covered with a single layer of heat-insulating film, with a stocking density of 40,000 to 50,000 shrimp fry per acre.

8. The method for staggered farming of giant freshwater prawns twice a year according to claim 1, characterized in that, During the greenhouse temperature-controlled breeding stage, the water temperature inside the greenhouse is controlled at 20℃~24℃, the water pH value is 7.2~8.6, the dissolved oxygen is 5 mg / L~7 mg / L, and the water exchange rate is 15%~25% per week.

9. The method for staggered farming of giant freshwater prawns twice a year according to claim 1, characterized in that, The staggered harvesting in batches is carried out using ground cage nets to catch the larger shrimp and leave the smaller ones. The first batch of shrimp is harvested in mid-May of the following year when the shrimp size is 25-30 g / tail, and in mid-June of the following year when the shrimp size is 30-35 g / tail. The second batch of shrimp is harvested in mid-to-late October of the following year when the shrimp size is ≥30 g / tail, and the pond clearing and harvesting are completed in early to mid-November of the following year.

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