Macrobrachium rosenbergii breeding method based on concentrated natural seawater

Abstract

The invention discloses a macrobrachium rosenbergii fry breeding method based on concentrated natural seawater, and relates to the technical field of aquaculture breeding, and the method comprises the following steps: S1, selecting surface seawater of a sea area of the northern bay of Guangxi, and sequentially carrying out pretreatment, concentration treatment and retreatment to obtain concentrated seawater; the pretreatment comprises precipitation, precise filtration and sterilization; the concentration treatment adopts a reverse osmosis method or is combined with a double-effect evaporation method, and the seawater is concentrated to 1 / 3-1 / 5 of the original volume; the retreatment comprises the following steps: adjusting the pH value to 7.8-8.2, adding an EDTA-2Na chelating agent, and carrying out precise filtration; s2, performing differential precipitation, three-stage gradient filtration and compatibility pre-detection on the selected water source to ensure that the turbidity of dilution water is less than or equal to 3NTU, the pH is 7.5-8.0, the ammonia nitrogen is less than or equal to 0.02 mg / L, and the residual chlorine is equal to 0mg / L. According to the method, through whole-course water quality management and staged accurate feeding, efficient, stable and green breeding from larvae to juvenile shrimps is achieved.

Description

Technical Field

[0001] This invention relates to the field of aquaculture breeding technology, and in particular to a method for breeding giant freshwater prawns based on concentrated natural seawater. Background Technology

[0002] As an important freshwater economic shrimp species, the development of its aquaculture industry is highly dependent on a stable supply of high-quality seedlings. The key to shrimp seedling cultivation lies in providing a suitable and stable brackish water environment for their zoea larval stage. Artificial seawater preparation is the most widely used technique, which uses freshwater as a base and adds inorganic salts such as sea salt, calcium chloride, and magnesium sulfate to simulate the ionic composition and salinity of natural seawater (typically 12–18‰). This technology has achieved precise control of basic parameters such as salinity and pH, meeting the needs of large-scale seedling production and eliminating dependence on geographical sea areas, making inland seedling production possible.

[0003] Artificial seawater has limitations in simulating the biological activity and ecological complexity of natural seawater. Natural seawater is a complex ecosystem containing various macro-elements, micro-elements, dissolved organic matter, and beneficial microorganisms, and the synergistic effects among its components are crucial for the healthy growth of aquatic organisms. While existing artificial seawater formulations can replicate the concentration of major ions, they struggle to reproduce the natural balanced ratio and bioavailable forms of micro-elements (such as selenium, cobalt, and molybdenum) found in natural seawater. The absence or imbalance of these components can lead to a lack of necessary biological activity in the culture water, affecting the physiological metabolism, immune resistance, and molting process of giant freshwater prawn larvae. Specifically, this manifests as larval survival rates and metamorphosis success rates (seedling rates) failing to reach optimal levels, thus hindering the development of high-yield and stable-yield seedling production technologies. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method for raising giant freshwater prawns based on concentrated natural seawater, which solves the problem that artificial seawater cannot replicate the natural balanced ratio of trace elements and their biological activity in natural seawater, thus making it difficult to achieve the optimal survival rate and seedling rate of giant freshwater prawn larvae.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for raising giant freshwater prawns based on concentrated natural seawater, comprising: S1, selecting surface seawater from the Beibu Gulf in Guangxi, and sequentially performing pretreatment, concentration treatment, and retreatment to obtain concentrated seawater; the pretreatment includes sedimentation, precision filtration, and sterilization; the concentration treatment uses reverse osmosis or a combination of double-effect evaporation to concentrate the seawater to 1 / 3 to 1 / 5 of its original volume; the retreatment includes adjusting the pH to 7.8-8.2, adding EDTA-2Na chelating agent, and precision filtration; S2. Perform differentiated sedimentation, three-stage gradient filtration, and compatibility pre-testing on the selected water source to ensure that the turbidity of the dilution water is ≤3NTU, pH 7.5-8.0, ammonia nitrogen ≤0.02mg / L, and residual chlorine =0mg / L; S3. Dilute the concentrated seawater obtained in step S1 with the dilution water obtained in step S2 to a salinity of 15‰. S4. Introduce the first stage (Z1) of the zoea larvae of Macrobrachium rosenbergii No. 1 into the seedling water, and carry out water quality management and precise feeding in stages until the larvae develop to the juvenile stage (P1).

[0007] As a preferred embodiment of the method for raising giant freshwater prawns based on concentrated natural seawater according to the present invention, wherein: in step S1, the pretreatment specifically includes: After the seawater was allowed to stand for 4-6 hours, it was filtered through a 0.22μm precision polypropylene filter membrane, and then subjected to a dose ≥30mJ / cm. 2 Sterilization is achieved by exposing the product to 254nm wavelength ultraviolet light or 0.5-1mg / L ozone for 15 minutes.

[0008] As a preferred embodiment of the method for raising giant freshwater prawns based on concentrated natural seawater according to the present invention, in step S1, when the concentration treatment is carried out by reverse osmosis, the operating pressure is controlled at 3.5-4.0 MPa and the temperature is controlled at 25-30℃; when the concentration is carried out by double-effect evaporation, the evaporation temperature is controlled at 60-70℃.

[0009] As a preferred embodiment of the method for raising giant freshwater prawns based on concentrated natural seawater according to the present invention, wherein: in step S1, the reprocessing specifically includes: The concentrated seawater was adjusted to pH 7.8-8.2 using food-grade sodium hydroxide or hydrochloric acid, and 0.01-0.02 g / L of EDTA-2Na was added. The solution was then finely filtered through a 0.1 μm polyvinylidene fluoride membrane.

[0010] As a preferred embodiment of the method for raising giant freshwater prawns based on concentrated natural seawater according to the present invention, wherein: in step S2, the three-stage gradient filtration includes: The filter is sequentially subjected to coarse filtration through a 120-mesh nylon screen, fine filtration through a double-layer composite sand filter of quartz sand and zeolite, fine filtration through a 0.1μm polyvinylidene fluoride membrane, and final protection through a 5μm security filter.

[0011] As a preferred embodiment of the method for raising giant freshwater prawns based on concentrated natural seawater according to the present invention, wherein: in step S4, the water quality management includes: Continuous aeration throughout the process to maintain dissolved oxygen levels ≥5 mg / L; daily siphon suction of sludge; according to larval development stages Adjust the frequency and volume of water exchange to maintain ammonia nitrogen concentration below 0.5 mg / L and nitrite concentration below 0.1 mg / L.

[0012] As a preferred embodiment of the method for raising giant freshwater prawns based on concentrated natural seawater according to the present invention, the water exchange specifically includes: When the larvae are in stages Z1-Z3, change the water twice a week, replacing 1 / 5 of the total water volume each time; When the body is in the Z4-Z10 stage, change the water 3-4 times a week, and change 1 / 4 of the total water volume each time; the temperature difference between the new water and the original water should be ≤0.5℃, the salinity difference should be ≤1‰, and the pH difference should be ≤0.3.

[0013] As a preferred embodiment of the method for raising giant freshwater prawns based on concentrated natural seawater according to the present invention, wherein: in step S4, the staged precise feeding specifically refers to: Z1-Z3 stage: Feed only Artemia nauplii larvae, 3-4 times a day, with each feeding of 5g of dried egg-hatched nauplii larvae per 100,000 larvae; Z4-Z7 stage: Feed brine shrimp nauplii 3-4 times a day, each time feeding 8g of dried egg-hatched nauplii 3g of dried egg-hatched nauplii per 100,000 nauplii. Z6-P1 stage: Feed brine nauplii and egg custard together. Feed brine nauplii 3-4 times a day and egg custard 2 times a day. Specifically, for Z6-Z8 stage, feed 8g of dried brine nauplii eggs and 20-30g of egg custard per 100,000 nauplii. For Z9-P1 stage, feed 8-10g of dried brine nauplii eggs and 40-50g of egg custard per 100,000 nauplii.

[0014] As a preferred embodiment of the method for raising giant freshwater prawns based on concentrated natural seawater according to the present invention, in step S4, the water temperature is controlled at 28-30℃, the light intensity is 1000-1500lx, and the light cycle is 12 hours of light / 12 hours of darkness.

[0015] As a preferred embodiment of the method for raising giant freshwater prawns based on concentrated natural seawater according to the present invention, the concentrated seawater obtained in step S1 is packaged in a food-grade HDPE sealed container, the container is filled with nitrogen and sealed, and transported and stored at 5-30℃, with a shelf life of 6 months.

[0016] The beneficial effects of this invention are as follows: by selecting surface seawater from the Beibu Gulf in Guangxi, pre-treatment, concentration treatment and re-treatment are carried out in sequence to obtain concentrated seawater. Then, combined with differentiated sedimentation, three-stage gradient filtration and compatibility pre-testing of dilution water, the concentrated seawater is diluted to a suitable salinity and then released into the zoea larvae of Macrobrachium rosenbergii No. 1. Through full-process water quality management and precise feeding in stages, efficient, stable and green seedling cultivation from larvae to shrimp larvae is achieved. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. 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.

[0018] Figure 1 Images of giant freshwater prawn larvae at different developmental stages.

[0019] Figure 2 The ammonia nitrogen content in the water used for laboratory culture of giant freshwater prawn larvae.

[0020] Figure 3 The nitrite content in the water used for culturing juvenile giant freshwater prawns in the laboratory was measured.

[0021] Figure 4 The ammonia nitrogen content in the water used for raising juvenile giant freshwater prawns in cement ponds.

[0022] Figure 5 The nitrite content in the water used for raising juvenile giant freshwater prawns in cement ponds. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "example" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The appearance of an embodiment in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments.

[0026] Example 1, referring to Figures 1-5 This is the first embodiment of the present invention, which provides a method for raising giant freshwater prawns based on concentrated natural seawater, including the following steps: Laboratory tank culture experiment of Giant freshwater prawn larvae, Shufeng No. 1 1. Experimental Materials Larvae source: 45,000 stage I (Z1) zoea larvae of Giant River Prawn No. 1 with uniform size and good vitality were selected.

[0027] Cultivation container: Use a 100L rigid plastic bucket. Before use, disinfect it by soaking it in potassium permanganate solution, rinse it repeatedly with clean water, and then let it dry.

[0028] The preparation of water for cultivation is as follows: Control group (artificial seawater group): Artificial seawater was prepared using a formula based on tap water, with the addition of sea salt, magnesium sulfate, calcium chloride, and other reagents to adjust the salinity to 15‰ and stabilize the pH at 7.8-8.2. The calcium (Ca) concentration was 172 mg / L and the sodium (Na) concentration was 4.334 × 10⁻⁶. 3 The concentrations of potassium (K) and magnesium (Mg) were 103 mg / L, 450 mg / L, 0.04 mg / L (below the detection limit) for copper (Cu), 0.02 mg / L for zinc (Zn), 0.8 μg / L for lead (Pb), and 0.16 μg / L for cadmium (Cd).

[0029] Guangxi natural seawater group: The concentrated seawater from Beibu Gulf prepared in this invention was diluted with freshwater that had undergone sedimentation and filtration treatment to a salinity of 15‰. The water quality indicators after dilution were: calcium (Ca) concentration 203 mg / L, sodium (Na) concentration 3.88 × 10⁻⁶. 3 mg / L, potassium (K) concentration 147 mg / L, magnesium (Mg) concentration 478 mg / L, copper (Cu) concentration 0.04 mg / L (below the detection limit), zinc (Zn) concentration 0.009 mg / L (below the detection limit), lead (Pb) concentration 0.3 μg / L (below the detection limit), cadmium (Cd) concentration 0.03 μg / L (below the detection limit), pH=7.9.

[0030] Natural seawater sample from Zhejiang (near Sanmen Bay, Xiangshan): Seawater from the surface 2-3 m of the nearshore waters of Zhejiang was collected, allowed to settle in a sedimentation tank for 6 hours, filtered through a 0.22μm precision polypropylene membrane, and sterilized with 254 nm wavelength ultraviolet light (dose ≥30mJ / cm). 2 The treatment involved adjusting the salinity to 15‰ and the pH to 7.7-8.1, with a calcium (Ca) concentration of 122 mg / L and a sodium (Na) concentration of 4.46 × 10⁻⁶. 3 The concentrations of potassium (K) and magnesium (Mg) were 128 mg / L, 409 mg / L, 0.04 mg / L (below the detection limit) for copper (Cu), 0.009 mg / L (below the detection limit) for zinc (Zn), 0.9 μg / L (below the detection limit) for lead (Pb), and 0.12 μg / L for cadmium (Cd).

[0031] Feed and equipment: hatched Artemia nauplii, freshly made egg custard; nano aeration discs, water quality analyzer (ammonia nitrogen, nitrite, dissolved oxygen), stereomicroscope.

[0032] 2. Test Methods Group setup: The experiment consisted of 3 groups: artificial seawater group (control group), Guangxi natural seawater group, and Zhejiang natural seawater group. Each group had 3 replicates, and each replicate tank contained 5000 juveniles of the No. 1 Z1 stage, with a culture water volume of 80L.

[0033] Cultivation conditions: Water temperature is controlled at 28-30℃ throughout the process, light intensity is 1000-1500 lx, and the light cycle is 12h light / 12h dark; continuous microbubble aeration is used with nano aeration discs to maintain dissolved oxygen in the water at ≥5 mg / L.

[0034] Water quality management: Siphon the sludge twice a day, morning and evening, to clean the bottom of the tank of uneaten food and feces; when the larvae develop to the Z1-Z3 stage, change the water twice a week, each time changing 1 / 5 of the total water volume; when they develop to the Z4-Z10 stage, change the water three times a week, each time changing 1 / 4 of the total water volume; when changing the water, ensure that the temperature difference between the new water and the original water is ≤ 0.5℃ and the salinity difference is ≤ 1‰; test the concentration of ammonia nitrogen and nitrite every 2 days; if the indicators exceed the standards, increase the water change volume in time and add EM bacteria to adjust the water quality.

[0035] Feeding: A precise feeding plan should be strictly implemented according to the different developmental stages of the larvae, as follows: Z1-Z3 stages: Feed only Artemia nauplii, 4 times a day, 3 hours apart, with each feeding amount being 0.5g / 10,000 nauplii; Z4-Z7 stages: Feed brine nauplii and egg custard together. Feed brine nauplii 4 times a day and egg custard 2 times a day, with an interval of 1.5 hours between feeding brine nauplii. The amount of brine nauplii fed gradually increases to 0.8-1g / 10,000 nauplii as the nauplii develop. Egg custard is fed from Z6 stage onwards at an amount of 2-3g / 10,000 nauplii.

[0036] Z8-P1 stage: Resume feeding with only Artemia nauplii, feed 4 times a day, gradually increase the amount of Artemia feeding to 1 g / 10,000 larvae as the larvae develop, and gradually increase the amount of egg custard feeding to 4-5 g / 10,000 larvae. Test index determination Survival rate: When the shrimp reaches the mysid larval stage, the number of surviving larvae in each repeated water tank is counted, and the survival rate is calculated according to the formula: survival rate = (number of surviving larvae / number of larvae released) × 100%.

[0037] Seedling turnover rate: Calculate the seedling turnover rate by counting the number of juvenile shrimp and using the formula: Seedling turnover rate = (number of juvenile shrimp / number of juveniles released) × 100%.

[0038] Water quality indicators: Dissolved oxygen values ​​of each group of water bodies are recorded daily, and ammonia nitrogen and nitrite concentrations are measured every 2 days. The average concentrations during the cultivation period are statistically analyzed.

[0039] 4. Experimental Results The experiment lasted 30 days. After the shrimp larvae were raised to the larval stage, statistical analysis was performed on various indicators of each group. The results showed that the average survival rates of the larvae in the control group (artificial seawater group), the Guangxi natural seawater group, and the Zhejiang natural seawater group were 78%±2%, 82%±2.3%, and 76%±3.2%, respectively, and their hatching rates were 42.8%±1.7%, 52.1%±1.6%, and 36.4%±2.7%, respectively. The ammonia nitrogen and nitrite contents in the Guangxi natural seawater group were slightly higher than those in the Zhejiang natural seawater group and the control group, but the differences were not significant. Figure 2 and Figure 3 Overall, the use of concentrated seawater from the Beibu Gulf in Guangxi prepared according to this invention for the breeding of giant freshwater prawns can significantly improve the survival rate and molting rate of Shufeng No. 1 larvae, demonstrating a clear advantage in breeding performance.

[0040] Example 2, the first embodiment of the present invention, provides a method for raising giant freshwater prawns based on concentrated natural seawater, including the following steps: Application of the No. 1 Giant Freshwater Prawn Seedling in Cement Ponds This embodiment aims to verify the applicability and superiority of the natural seawater seedling cultivation technology of the present invention in a large-scale cement pond cultivation scenario, simulate the actual production conditions of a seedling farm, and provide data support for the industrialization and promotion of the technology.

[0041] 1. Experimental Materials Larvae source: A total of 9 million healthy larvae of the Giant River Prawn No. 1 Zoat-like larvae (Z1) of uniform size (0.8-1.0 mm in body length), good vitality, and free from injury or disease were selected. All of them came from the same batch of hatched healthy larvae.

[0042] Cultivation container: A standard cement pond from a seedling nursery, measuring 10m × 5m × 1.2m (length × width × depth), with an effective water volume of 40m³. 3 (40000L). Before use, soak the entire pool for 24 hours by splashing with a 100mg / L potassium permanganate solution, then rinse repeatedly with clean water 3 times, and let it dry before use; at the same time, check the impermeability of the pool and the sewage system to ensure that there is no leakage and the sewage is discharged smoothly.

[0043] Preparation of water for cultivation: The formulas, water quality indicators, and treatment processes for the three groups of water for cultivation were consistent with those in Example 1, with the salinity uniformly controlled at 15‰, as detailed below: Control group (artificial seawater group): Freshwater that meets the "Fishery Water Quality Standard" (GB 11607-1989) is used as the base. Specifically, 11,000 g of sodium chloride, 3,700 g of magnesium sulfate, 420 g of calcium chloride, 190 g of potassium chloride, 20 g of sodium bicarbonate, 20 g of potassium bromide, 120 g of boric acid, 6 g of EDTA, and 1 g of strong chlorine are added per ton of water. After being fully dissolved, the mixture is aerated for 24 hours and then set aside. The initial salinity is 15‰.

[0044] Guangxi natural seawater group: The concentrated seawater from Beibu Gulf prepared in this invention (concentration ratio 1:5) was diluted to a salinity of 15‰ with freshwater that had passed sedimentation, 3-stage gradient filtration and compatibility testing; after dilution, the pH was 7.9, the concentration of key elements was consistent with that in Example 1, and the heavy metal content was all below the detection limit.

[0045] Feed and equipment: Hatched brine shrimp nauplii, freshly made egg custard; nano-aeration pipes (with high-power Roots blowers), bottom drainage system, automatic feeder, online water quality monitor (real-time monitoring of dissolved oxygen, pH, and salinity), and portable water quality analyzer (detecting ammonia nitrogen and nitrite).

[0046] 2. Test Methods Group setup: The experiment consisted of two groups: a control group (artificial seawater group) and a Guangxi natural seawater group. Each cement pond was stocked with 1.5 million Z1 stage larvae of the Shufeng No. 1 cultivar, at a stocking density of 50,000 larvae / m³. 3 The cultivation water volume is 30 m³. 3 .

[0047] Cultivation conditions: Water temperature is controlled at 28-30℃ using constant temperature heating equipment throughout the process, with an error ≤0.5℃; light intensity is regulated to 1000-1500 lx using shade nets, with a light cycle of 12 hours of light / 12 hours of darkness; aeration is uniformly distributed throughout the entire area via nano-aeration pipes (aeration density of 10m pipe / 100m). 2 (At the bottom of the pool), continuous aeration is maintained throughout the process to keep the dissolved oxygen level in the water ≥5mg / L, ensuring that there are no dead spots in the dissolved oxygen in the pool.

[0048] 2.3 Water Quality Management: A combination of bottom drainage and siphon suction is used to clean up waste. The bottom drainage system is activated for 30 minutes daily at 9:00 AM, while simultaneously using a siphon suction pipe to clean uneaten food and feces accumulated in the corners and edges of the pond. When the larvae reach stages Z1-Z3, the water is changed twice a week, with each change replacing 1 / 5 (8m³) of the total water volume. 3When the organism reaches the Z4-Z10 stage, change the water 3-4 times per week, replacing 1 / 4 of the total water volume each time. The new water must be aerated in the storage tank for 24 hours beforehand to ensure the temperature difference between the new and old water is ≤0.5℃, salinity difference is ≤1‰, and pH difference is ≤0.3. Test ammonia nitrogen and nitrite concentrations every 2 days. If ammonia nitrogen >0.5mg / L or nitrite >0.1mg / L, immediately increase the water replacement volume to 1 / 3 of the total water volume and add 0.5g / m³ of [agent / renewal agent / treatment]. 3 EM bacteria regulate the balance of the aquatic flora.

[0049] Feeding: An automatic feeder combined with manual supplementary feeding was used. A precise feeding plan was strictly implemented according to the different developmental stages of the larvae. The feeding amount was scaled up according to Example 1, as follows: Z1-Z2 stage: Only Artemia nauplii are fed, 4 times a day (7:00, 10:00, 14:00, 17:00) via automatic feeder, with a 3-hour interval between feedings, and each feeding amount is 0.5 g / 10,000 nauplii; Z3-Z8 stages: Artemia nauplii and egg custard are fed together. Artemia are fed 4 times a day via automatic feeder, and egg custard is supplemented 2 times manually (10:00 and 16:00), with an interval of 1.5 hours between feeding Artemia and feeding Egg custard. The amount of Artemia feed is gradually increased to 0.8-1.0 g / 10,000 nauplii as the nauplii develop. Egg custard is fed from Z6 stage, with a feeding amount of 2-3 g / 10,000 nauplii. Z9-P1 stage: Feed brine shrimp 4 times a day, each time at a rate of 1.0 g / 10,000 shrimp; gradually increase the amount of egg custard feeding to 4-5 g / 10,000 shrimp.

[0050] Check for uneaten feed one hour after each feeding. If there is uneaten feed left at the bottom of the pond, reduce the amount of feed by 10%-20% for the next feeding.

[0051] 3. Determination of test indicators Survival rate: When the shrimp are raised to the larval stage, a five-point sampling method is used to randomly sample the four corners and the central area of ​​each cement pond. Each sampling is 200 shrimp. The number of surviving larvae is counted. The average survival rate of each group is calculated according to the formula: survival rate = (number of surviving larvae / number of larvae released) × 100%.

[0052] Transformation rate: The time from Z1 stage to larvae was recorded. The number of larvae in each pond was counted by sampling the entire pond. The average transformation rate of each group was calculated using the formula: Transformation rate = (Number of larvae / Number of juveniles introduced) × 100%.

[0053] Water quality indicators: Dissolved oxygen levels in each group of water bodies were recorded in real time using an online water quality monitoring instrument. Ammonia nitrogen and nitrite concentrations were measured every two days using a portable water quality analyzer. The average concentrations over the cultivation period were statistically analyzed, and water quality change curves were plotted. Figure 4 , Figure 5).

[0054] 4. Experimental Results The experiment lasted 25 days. Results showed that the average survival rate of larvae in the natural seawater group from Guangxi was greater than 75%, and the average molting rate was greater than 65%, significantly higher than that in the artificial seawater group (survival rate 65%, molting rate 55%). There was no significant difference in ammonia nitrogen and nitrite content between the natural seawater group and the control group from Guangxi. Figure 4 , Figure 5 Furthermore, no larval mortality due to water quality deterioration occurred throughout the entire process. In summary, in large-scale cement pond breeding scenarios, the use of concentrated seawater from the Beibu Gulf in Guangxi prepared according to this invention for the cultivation of Macrobrachium rosenbergii larvae (Shufeng No. 1) still improves larval survival and seedling rate, maintains water environment stability, meets the needs of large-scale production, and has good prospects for industrial application.

[0055] Example 3, referring to Figures 1-5 This is the first embodiment of the present invention, which provides a method for raising giant freshwater prawns based on concentrated natural seawater, including the following steps: The purpose of this invention is to overcome the shortcomings of existing technologies and provide a natural seawater seedling cultivation technology for giant freshwater prawns and its application. Addressing the pain points of traditional seedling cultivation methods, such as easy water quality deterioration, inconsistent seedling quality, and low efficiency in large-scale cultivation, this technology uses natural seawater as the core cultivation medium. It fully utilizes the advantages of its natural mineral and trace element ratios to optimize the larval growth and development environment, accelerate molting and growth rates, and significantly improve hatching rate and seedling robustness. This invention breaks through the limitations of artificial seawater formulations, enabling green, efficient, and large-scale cultivation of giant freshwater prawn seedlings, providing technical support for the high-quality development of the aquaculture industry.

[0056] To achieve the above objectives, the technical solution designed by the present invention is as follows: This invention provides a natural seawater breeding technology for giant freshwater prawns, which involves production, concentration, transportation, and larval rearing.

[0057] The objective of this invention is achieved through the following technical solution: This invention provides a natural seawater for the cultivation of giant freshwater prawn larvae. This natural seawater is taken from the Beibu Gulf in Guangxi and has the significant advantage of a naturally balanced ratio of minerals and trace elements. It can precisely meet the growth and development needs of larvae, effectively promote molting and growth, improve seedling vigor, and provide a high-quality cultivation medium for the green and efficient cultivation of giant freshwater prawns.

[0058] The final elemental concentrations in the seawater used for seedling cultivation in Guangxi are as follows: calcium (Ca) concentration is 203 mg / L, and sodium (Na) concentration is 3.88 × 10⁻⁶ mg / L. 3The concentrations of potassium (K) and magnesium (Mg) were 147 mg / L, 478 mg / L, 0.04 mg / L (L indicates below the detection limit), 0.009 mg / L (L indicates below the detection limit), 0.3 μg / L (L indicates below the detection limit), and 0.03 μg / L (L indicates below the detection limit).

[0059] To convert seawater from the Beibu Gulf into transportable concentrated seawater, a process involving pretreatment, concentration, retreatment, and packaging for transportation is required. The specific steps are as follows: Pretreatment (to ensure water purity): Clean seawater from the surface 2-3 meters of the Beibu Gulf is first introduced into a sedimentation tank and allowed to stand for 4-6 hours to settle large suspended particles such as silt; then it is filtered through a 0.22 μm precision polypropylene membrane to remove plankton and colloidal impurities; finally, it is sterilized with 254 nm wavelength ultraviolet light (dose ≥30 mJ / cm²). 2 Alternatively, 0.5-1 mg / L of ozone can be introduced for 15 minutes to inactivate harmful microorganisms and prevent subsequent spoilage.

[0060] Concentration treatment (preserving core minerals): Reverse osmosis is used (low energy consumption adapted to seedling needs). Pretreated seawater is pumped into the reverse osmosis unit, and the operating pressure is controlled at 3.5-4.0 MPa and the temperature at 25-30℃ (matching the normal temperature of seawater in the Beibu Gulf). Water is separated using a semi-permeable membrane, and the seawater is concentrated to 1 / 3 of its original volume (i.e., 1 part concentrated seawater corresponds to 3 parts original seawater). This process can completely preserve key minerals for seedling cultivation such as calcium and magnesium. For large-scale production, a double-effect evaporation can be used to assist, controlling the evaporation temperature at 60-70℃ (low temperature avoids element deactivation), further increasing the concentration ratio to 1 / 5.

[0061] Retreatment (stabilizing water quality): The pH of the concentrated seawater is adjusted to 7.8-8.2 (suitable for the survival of giant freshwater prawn larvae) using food-grade sodium hydroxide / hydrochloric acid. 0.01-0.02 g / L of EDTA-2Na chelating agent is added to prevent the precipitation of calcium and magnesium ions. The water is then finely filtered through a 0.1 μm polyvinylidene fluoride filter membrane to ensure that there are no residual impurities.

[0062] Packaging and Transportation (Ensuring Storage and Transportation Safety): Pack the concentrated seawater into food-grade HDPE sealed containers (25L / container), fill the container with a small amount of nitrogen (to prevent air oxidation), and then tighten and seal it; label the container with concentrated seawater from Beibu Gulf (1:5), pH 7.8-8.2, shelf life 6 months. Avoid stacking more than 5 layers during transportation, and control the temperature between 5-30℃ to prevent damage to the container or fluctuations in water quality.

[0063] The water used to dilute and concentrate seawater must undergo three processes: sedimentation, filtration, and testing. Specific details are as follows: Differentiated sedimentation treatment (adapted to the characteristics of diverse water sources) For dilution, priority should be given to natural freshwater or low-turbidity surface seawater from the Beibu Gulf that meets the "Fishery Water Quality Standard" (GB 11607-1989). If tap water is used, it must be pre-treated by aeration to remove chlorine. Different treatment methods are applied to different water sources: For natural freshwater or low-turbidity seawater, add 0.2-0.4 mg / L food-grade polyferric sulfate flocculant, stir well, and let stand for 10-14 hours to accelerate the coagulation and sedimentation of silt, algae, and colloidal particles through flocculation; for tap water, it must first be continuously aerated for 24 hours (aeration intensity 2.0 m). 3 / (m 2 After removing residual chlorine, it is placed in a sedimentation tank and left to stand for 8 hours.

[0064] 3-stage gradient filtration (ensuring compatibility and cleanliness) A three-stage filtration system is adopted, consisting of coarse filtration, composite sand filtration, fine filtration, and terminal protection, to gradually remove various impurities while optimizing water quality parameters to suit concentrated seawater.

[0065] Coarse filtration stage: The precipitated clear liquid is passed through a 120-mesh nylon screen (pore size 0.125 mm) to filter out small planktonic organisms, flocculent flocculations and large particulate impurities that have not settled completely, preventing clogging of subsequent filtration units.

[0066] Composite sand filtration stage: The coarsely filtered water is pumped into a quartz sand + zeolite double-layer filter column with a height of 1.8 m. The quartz sand layer (particle size 0.8-1.2 mm, layer height 1.0 m) is responsible for removing colloidal particles and fine suspended solids in the water; the zeolite layer (particle size 2-3 mm, layer height 0.6 m) removes ammonia nitrogen, nitrite and trace heavy metal ions through adsorption.

[0067] Fine filtration and terminal protection: First, the water is filtered through a 0.1μm polyvinylidene fluoride membrane to thoroughly remove bacteria, viruses, microcolloids and residual organic matter; then, it is filtered through a 5μm security filter to intercept any filter membrane debris that may detach.

[0068] Compatibility pre-detection (avoiding the risk of cross-contamination) After filtration, the dilution water is first tested for basic indicators, requiring turbidity ≤3 NTU, pH 7.5-8.0, ammonia nitrogen ≤0.02 mg / L, and residual chlorine = 0 mg / L. Only after meeting the standards can the concentrated seawater be diluted.

[0069] The giant freshwater prawn larvae cultivated in this invention are the nationally approved new variety, Shufeng No. 1, which was innovatively cultivated by our team.

[0070] Giant freshwater prawn larvae are extremely sensitive to changes in water quality, and a high-quality, stable aquatic environment is crucial for their survival. Water quality management revolves around three main operations: aeration, sludge removal, and water exchange, combined with regular testing of ammonia nitrogen and nitrite levels to create a healthy aquatic ecosystem. Specific requirements are as follows: Aeration must be continuous throughout the entire process, using nano-aeration discs or air stones to evenly distribute air and maintain a dissolved oxygen level of ≥5mg / L in the water. Adjust the aeration intensity according to the different stages of the larvae. In the early stages, focus on microbubbles to avoid strong water flow impacting the larvae; in the later stages, the aeration intensity can be appropriately increased to promote water circulation and prevent oxygen deficiency at the bottom. Aeration equipment needs to be cleaned regularly to prevent clogging and maintain aeration efficiency.

[0071] Sludge removal aims to remove uneaten food, feces, and other pollutants, reducing the risk of water quality deterioration. It should be performed twice daily, morning and evening, using a siphon-type suction pipe that moves slowly along the bottom of the pool, focusing on cleaning the corners and areas where debris accumulates. During operation, avoid stirring up too much sludge at the bottom of the pool to prevent turbidity from affecting the juveniles' feeding and survival.

[0072] Water changes should follow the principle of small, frequent changes to avoid drastic fluctuations in water quality. Initially, change the water 1-2 times per week, replacing 1 / 5-1 / 4 of the total water volume each time. Later, as the juveniles grow and the amount of food increases, this can be increased to 3-4 times per week, with each replacement not exceeding 1 / 3 of the water volume. The new water should be aerated beforehand to ensure that the temperature, salinity, and pH are close to the original water, and that the pH is stable between 7.5 and 8.5.

[0073] Ammonia nitrogen and nitrite are key water quality indicators during the larval rearing period and require regular testing. It is recommended to test at least every two days, keeping ammonia nitrogen concentration below 0.5 mg / L and nitrite concentration below 0.1 mg / L. If the test values ​​exceed the standards, the water exchange volume should be increased immediately, and appropriate amounts of EM bacteria, photosynthetic bacteria, and other microecological agents should be added to regulate the balance of the aquatic flora and reduce the concentration of harmful substances.

[0074] During the rearing of giant freshwater prawn larvae, brine shrimp and egg custard are commonly used feeds. The timing, frequency, and amount of their use need to be accurately matched to the developmental stage of the giant freshwater prawn larvae. Figure 1 The key points for its use are shown in the table below:

[0075] In summary, this invention selects surface seawater from the Beibu Gulf in Guangxi, and sequentially pre-treats, concentrates, and re-treats it to obtain concentrated seawater. Then, combined with differentiated sedimentation, three-stage gradient filtration, and compatibility pre-testing of the dilution water, the concentrated seawater is diluted to a suitable salinity before releasing the zoea larvae of Macrobrachium rosenbergii No. 1. Through full-process water quality management and precise feeding in stages, efficient, stable, and green seedling cultivation from larvae to shrimp larvae is achieved.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for raising giant freshwater prawns based on concentrated natural seawater, characterized in that: include, S1. Select surface seawater from the Beibu Gulf in Guangxi and subject it to pretreatment, concentration, and retreatment in sequence to obtain concentrated seawater. The pretreatment includes sedimentation, precision filtration, and sterilization. The concentration process uses reverse osmosis or a combination of reverse osmosis and double-effect evaporation to concentrate the seawater to 1 / 3 to 1 / 5 of its original volume. The retreatment includes adjusting the pH to 7.8-8.2, adding EDTA-2Na chelating agent, and precision filtration. S2. Perform differentiated sedimentation, three-stage gradient filtration, and compatibility pre-testing on the selected water source to ensure that the turbidity of the dilution water is ≤3NTU, pH 7.5-8.0, ammonia nitrogen ≤0.02mg / L, and residual chlorine =0mg / L; S3. Dilute the concentrated seawater obtained in step S1 with the dilution water obtained in step S2 to a salinity of 15‰. S4. Introduce the first stage (Z1) of the zoea larvae of Macrobrachium rosenbergii No. 1 into the seedling water, and carry out water quality management and precise feeding in stages until the larvae develop to the juvenile stage (P1).

2. The method for raising giant freshwater prawns based on concentrated natural seawater as described in claim 1, characterized in that: In step S1, the preprocessing specifically includes: After allowing the seawater to stand for 4-6 hours, it was filtered through a 0.22μm precision polypropylene filter membrane, and then subjected to a dose ≥30mJ / cm. 2 Sterilization is achieved by exposing the product to 254nm wavelength ultraviolet light or 0.5-1mg / L ozone for 15 minutes.

3. The method for raising giant freshwater prawns based on concentrated natural seawater as described in claim 2, characterized in that: In step S1, when the concentration treatment uses reverse osmosis, the operating pressure is controlled at 3.5-4.0 MPa and the temperature is controlled at 25-30℃; when double-effect evaporation is used to assist concentration, the evaporation temperature is controlled at 60-70℃.

4. The method for raising giant freshwater prawns based on concentrated natural seawater as described in claim 3, characterized in that: In step S1, the reprocessing specifically includes: The concentrated seawater was adjusted to pH 7.8-8.2 using food-grade sodium hydroxide or hydrochloric acid, and 0.01-0.02 g / L of EDTA-2Na was added. The solution was then finely filtered through a 0.1 μm polyvinylidene fluoride membrane.

5. The method for raising giant freshwater prawns based on concentrated natural seawater as described in claim 1, characterized in that: In step S2, the three-level gradient filtering includes: The filter is sequentially subjected to coarse filtration through a 120-mesh nylon screen, fine filtration through a double-layer composite sand filter of quartz sand and zeolite, fine filtration through a 0.1μm polyvinylidene fluoride membrane, and final protection through a 5μm security filter.

6. The method for raising giant freshwater prawns based on concentrated natural seawater as described in claim 1, characterized in that: In step S4, the water quality management includes: Continuous aeration throughout the process to maintain dissolved oxygen levels ≥5 mg / L; daily siphon suction of sludge; according to the developmental stages of larvae Adjust the frequency and volume of water exchange to keep ammonia nitrogen concentration below 0.5 mg / L and nitrite concentration below 0.1 mg / L.

7. The method for raising giant freshwater prawns based on concentrated natural seawater as described in claim 6, characterized in that: The water exchange specifically refers to: When the larvae are in stages Z1-Z3, change the water twice a week, replacing 1 / 5 of the total water volume each time; When the water is in the Z4-Z10 stage, change the water 3-4 times a week, and change 1 / 4 of the total water volume each time; the temperature difference between the new water and the original water should be ≤0.5℃, the salinity difference should be ≤1‰, and the pH difference should be ≤0.

3.

8. The method for raising giant freshwater prawns based on concentrated natural seawater as described in claim 1, characterized in that: In step S4, the staged precise feeding specifically refers to: Z1-Z3 stage: Feed only Artemia nauplii larvae, 3-4 times a day, with each feeding of 5g of dried egg-hatched nauplii larvae per 100,000 larvae; Z4-Z7 stage: Feed brine shrimp nauplii 3-4 times a day, each time feeding 8g of dried egg-hatched nauplii 3g of dried egg-hatched nauplii per 100,000 nauplii. Z6-P1 stage: Feed brine nauplii and egg custard together. Feed brine nauplii 3-4 times a day and egg custard 2 times a day. Specifically, for Z6-Z8 stage, feed 8g of dried brine nauplii eggs and 20-30g of egg custard per 100,000 nauplii. For Z9-P1 stage, feed 8-10g of dried brine nauplii eggs and 40-50g of egg custard per 100,000 nauplii.

9. The method for raising giant freshwater prawns based on concentrated natural seawater as described in claim 1, characterized in that: Step S4: Control the water temperature to 28-30℃, the light intensity to 1000-1500lx, and the light cycle to 12 hours of light / 12 hours of darkness.

10. The method for raising giant freshwater prawns based on concentrated natural seawater as described in claim 1, characterized in that, The concentrated seawater obtained in step S1 is packaged in a food-grade HDPE sealed container, which is filled with nitrogen and sealed. It is transported and stored at 5-30°C and has a shelf life of 6 months.

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