Saline-alkali-resistant breeding domestication and long-distance transportation method for larvae of kiss bass

Abstract

The invention discloses a saline-alkaline-tolerant breeding domestication and long-distance transportation method for larvae of kiss bass. The method comprises the following steps: (1) hatching fertilized eggs; (2) breeding in a hatching pond; (3) culturing in an indoor culture pond; (4) gradually desalting and domesticating; (5) carrying out a long-distance transportation simulation test: (5.1) blending a water body; (5.2) starvation and cooling pretreatment before transportation; (5.3) optimizing the bagging density; (5.4) low-temperature oxygenation sealing and transportation; (5.5) buffering the temperature and water quality after landing into the pool; according to the method, the in-transit stress and death risk can be effectively reduced, the long-distance transportation survival rate and field adaptability are improved, technical support is provided for large-scale cultivation and cross-regional supply of the kiss bass in the inland saline-alkali area, and the method has good application prospects and economic value.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture and live animal transportation technology, specifically relating to a method for salt-tolerant breeding and domestication of barramundi fry and long-distance transportation. Background Technology

[0002] Barramundi ( Lates calcarifer As an important economic fish species, the barramundi is rich in high-quality protein, essential amino acids, and omega-3 unsaturated fatty acids. It enjoys high market recognition and stable demand, possessing promising prospects for industrial development. Currently, barramundi farming in my country is mainly concentrated in coastal areas such as Guangdong and Fujian. Meanwhile, inland regions (such as Xinjiang, Ningxia, and Inner Mongolia) are rich in saline-alkali land and water resources, but these water bodies generally exhibit characteristics such as lower salinity than mariculture environments and higher total alkalinity and pH. Traditional mariculture technologies are difficult to directly adapt to these conditions, resulting in low resource utilization rates.

[0003] The barramundi has a wide range of salinity and can adapt to saline-alkali water environments within a certain range through salt and alkali tolerance acclimatization. However, the existing acclimatization technology for the seedling stage is not yet mature. The key parameters (salinity, alkalinity, pH, and temperature) lack standardization and operable procedures. Seedlings are sensitive to osmotic pressure and alkali stress, and are prone to feeding suppression, decreased physical condition and secondary infections, which affect the survival rate and subsequent growth, thus restricting the large-scale aquaculture promotion in saline-alkali waters.

[0004] In recent years, domestic scholars have begun to pay attention to the salt tolerance domestication of barramundi. For example, a research team from the Chinese Academy of Fishery Sciences has successfully achieved the cultivation of barramundi in water with a salinity of 10‰ by gradually reducing the salinity. However, most of these studies are still in the laboratory stage and lack verification for large-scale industrial application. At the same time, research on the physiological response mechanism and osmotic regulation mechanism of barramundi larvae under different salinity gradients is still not in-depth.

[0005] Cross-regional seedling transportation is a crucial link in the industry's layout. Traditional land transportation relies on refrigerated trucks or water trucks, maintaining survival through cooling, oxygenation, and water exchange. However, under long-distance conditions, problems remain, such as low survival rates (approximately 60%–70% from Guangdong to Xinjiang), long transit times (over 48 hours easily induces disease), and poor adaptability upon arrival. Although air logistics combined with constant temperature oxygenation and environmental gradient control can achieve cross-regional transfer within 24 hours, specialized air transport parameters for barramundi juveniles and seamless integration solutions for saline-alkali water acclimatization are still lacking.

[0006] In summary, existing technologies have shortcomings in both the "salt-alkali tolerance acclimatization system for barramundi juveniles in saline-alkali water" and the "high survival rate and fast long-distance transportation system." The lack of coordination between these two aspects easily leads to cumulative stress and increased losses. There is an urgent need to establish a standardized and scalable integrated technical solution to achieve organic integration of in-transit control and on-site saline-alkali water acclimatization. This would improve the survival rate and adaptability during cross-regional transport, shorten the acclimatization cycle, stabilize aquaculture results, and enhance the comprehensive utilization and industrial benefits of inland saline-alkali water resources. Summary of the Invention

[0007] The purpose of this invention is to provide a method for salt-tolerant breeding and domestication of barramundi fry and for long-distance transportation. This method can expand the breeding range of barramundi in inland saline-alkali areas, improve the survival rate and adaptability of cross-regional transportation, and ensure their healthy growth in the future.

[0008] The first objective of this invention can be achieved through the following technical solution: a method for salt-tolerant breeding and long-distance transportation of barramundi juveniles, comprising the following steps: (1) Hatching of fertilized eggs: Hatching barramundi fertilized eggs in an incubation tank; (2) Hatching pond cultivation: The day after the fertilized eggs show their tails, they are moved to an outdoor hatching pond for breeding management. Breeding management includes breeding density, water quality control and feed feeding. When the seedlings grow to 0.7~0.8cm, they are moved to an indoor breeding pond. (3) Indoor culture pond cultivation: The initial water parameters of the indoor culture pond are consistent with those of the outdoor hatching pond, and the type and amount of starter feed are adjusted according to the growth process of the seedlings; (4) Gradual desalination and acclimatization: When the seedlings are 1.4-1.6 cm long, seawater desalination begins. Fresh water is added to the culture pond. The salinity is gradually reduced and stabilized at 5‰±1‰ within 3-4 days, and the total alkalinity is stabilized at 3-4 mmol / L. During the acclimatization process, the seedlings' swimming and feeding are observed regularly to ensure good vitality and no abnormal stress. The seedlings are considered to have completed salinity and alkalinity acclimatization when they are healthy and stable in water with a salinity of 5‰±1‰ and a total alkalinity of 3-4 mmol / L. (5) Conduct long-distance transportation simulation tests: (5.1) Water preparation: Prepare water at a volume ratio of fresh water to seawater of 4 to 6 to 1, adjust the salinity to 5 ± 1‰, stabilize the total alkalinity at 3 to 4 mmol / L, and stabilize the dissolved oxygen at 8 to 10 mg / L. Before packaging, test and ensure that the pH is 7.8 to 8.6 and the ammonia nitrogen is ≤0.01 mg / L. (5.2) Starvation and cooling pretreatment before transportation: Select individuals with intact bodies and active swimming. Starve them for 46-50 hours before transportation. Use ice packs to circulate and cool them down. Gradually reduce the water temperature from 28±1℃ to 21±1℃ at a rate of ≤2℃ / h. Monitor the temperature throughout the process and keep the cooling rate stable. (5.3) Bag density optimization: (5.3) Bag density optimization: Before packaging, the initial water temperature was set to 21±1℃. The salinity was retested to 5±1‰, the total alkalinity to 3~4mmol / L, the dissolved oxygen to 8~10mg / L, and the initial ammonia nitrogen to <0.01mg / L. After the indicators met the standards, the seedlings and water that had undergone starvation and cooling pretreatment were packaged in transparent bags. The transparent bags were placed in foam boxes and the temperature of the foam boxes was maintained at 21±1℃. The foam boxes were placed in transport vehicles to simulate transport vibration for 11~13 hours. The physiological state of the seedlings and changes in the water were observed regularly. After screening, the bag density was obtained as follows: 2.2~2.8cm, 600~800 fish per bag; (5.4) Low temperature oxygenation sealing and transportation: The seedlings that have undergone starvation and cooling pretreatment are bagged according to the water prepared in step (5.1) and the parameters selected in step (5.3). After the air in the bag is exhausted, oxygen is added and sealed to maintain a low temperature environment. The seedlings are transported by air to the destination airport. After receiving the goods, they are transported to the breeding farm by refrigerated truck and prepared for entry into the pond. (5.5) Temperature and water quality buffering after landing: After long-distance transportation, the seedlings arrive at the saline-alkali water aquaculture base. The salinity of the saline-alkali water aquaculture base is adjusted to 5±1‰, the total alkalinity to 4±1 mmol / L, and the temperature to 25±1℃. The transparent bag is first used to balance the temperature, and then the aquaculture pond water is added into the transparent bag. After the seedlings adapt to the water quality change, the seedlings and the mixed water are transferred to the aquaculture pond or net cage.

[0009] In the above methods for salt-tolerant breeding and long-distance transportation of barramundi juveniles: Preferably, in step (1), when hatching barramundi fertilized eggs in the hatching tank, the hatching water is seawater with a salinity of 30‰ and a total alkalinity of 3-4 mmol / L, the temperature is controlled at 28-31℃, and the dissolved oxygen is controlled at 8-10 mg / L. During the hatching period, the molting of the fertilized eggs is observed regularly and the floating egg membrane is cleaned.

[0010] Preferably, in step (2), the fertilized eggs are transferred to the hatching pond the day after the tail of the fish appears, and the temperature difference and salinity difference are less than 2℃ and less than 5‰ when the seedlings are introduced into the pond.

[0011] Preferably, the stocking density in step (2) is 1600–2400 fish / m². 3Water quality control in the hatching pond includes: salinity of 30‰, total alkalinity of 3-4 mmol / L, temperature of 28-31℃, dissolved oxygen of 6-8 mg / L, pH of 7.6-8.2, ammonia nitrogen ≤0.3 mg / L, and nitrite ≤0.25 mg / L. Feeding includes feeding rotifers at fixed points around the oxygen pump twice a day, at 8:00 and 15:00, with a feeding amount of 1.5-2% of the total fish mass. After feeding, observe the feeding status of the fry, take samples to check the amount of uneaten feed, and adjust the subsequent feeding amount accordingly. After the fry grow to 0.7-0.8 cm, they are transferred to indoor rearing ponds. The temperature difference during transfer should be <2℃ and the salinity difference should be <5‰.

[0012] Preferably, the stocking density in the indoor aquaculture pond in step (3) is 3200–4800 fish / m². 3 Feed them mainly with rotifers, supplemented with frozen worms and brine shrimp drip feed, 2-3 times a day, with the amount of feed being 1.5-2% of the total body weight of the fish. After feeding, observe feeding and uneaten feed, and adjust the feeding in time. Use a net to clean up uneaten feed on the water surface and use a bottom suction device to remove the residue at the bottom. Turn off the aeration equipment during operation. During the breeding period, conduct feeding training with powdered feed every afternoon.

[0013] Preferably, in step (3), the feed transition is carried out during the process of adjusting the type and amount of starter feed. Initially, 0.3 type powdered feed is used. As the seedlings grow, they are periodically screened and graded. Seedlings of different sizes are transferred to breeding ponds with consistent breeding conditions. The feed particle size and formula are adjusted according to the feeding ability and growth needs of seedlings of different sizes. If necessary, vitamin C feed additives are mixed into the feed to reduce stress and improve resistance. In the case of insufficient feeding in the early stage of individual grouping, in addition to fixed-point feeding, a small amount of feed is added in a small scattered area. Frozen insects are fed by drip feeding to ensure that the seedlings at the bottom of the pond can also ingest feed.

[0014] Preferably, in steps (2) to (4), the seedlings are regularly screened and graded according to the difference in body length and weight, and the seedlings of different sizes are raised in separate ponds. The water quality parameters of the new pond are kept consistent with those of the original pond. The seedlings are graded every 3 to 5 days. If there is obvious cannibalism, feeding is stopped first, and screening is carried out 8 to 12 hours after feeding is stopped. Seedlings of different sizes are transferred to different net cages or aquaculture ponds. After grading, povidone-iodine solution is diluted with water according to the ratio and evenly sprinkled to reduce stress and disinfect the water.

[0015] Preferably, daily water quality testing is conducted throughout the entire aquaculture cycle in steps (2) to (4). The water quality testing indicators include dissolved oxygen 6-8 mg / L, transparency 30-40 cm, pH 7.6-8.2, alkalinity 3-4 mmol / L, and ammonia nitrogen ≤0.01 mg / L. At the same time, the water temperature is controlled at 27-32℃. When the transparency is low or the pH is <7.1, photosynthetic bacteria are added to the water to improve the water quality and microecology. When ammonia nitrogen >0.1 mg / L or nitrite >0.3 mg / L, the corresponding water quality control reagents are added in time for treatment.

[0016] Preferably, steps (2) to (4) also include nutritional fortification: the daily feeding amount is determined according to the total mass of the fish in the pond, and the feeding method is adopted twice a day, with a total amount of 1.2 to 1.8% (more preferably 1.5%) of the total mass of the fish. This satisfies the metabolic needs while avoiding water quality deterioration. The feed type is matched with the growth stage: powdered feed is used to promote feeding and acclimatization during the seedling stage, and high-protein extruded feed is used to promote rapid growth during the juvenile stage. Electrolyte multivitamins are added to the feed, with vitamin C as the main component, to enhance stress resistance and immune function.

[0017] More preferably, in step (5.1), the water preparation is as follows: the water is prepared according to the volume ratio of fresh water to seawater = 5:1, the salinity is adjusted to 5±1‰, the total alkalinity is stabilized at 3 to 4 mmol / L, the dissolved oxygen is stabilized at 8 to 10 mg / L, and the pH is tested and ensured to be 7.8 to 8.6 and ammonia nitrogen ≤ 0.01 mg / L before packaging.

[0018] Preferably, step (5.1) also includes oxygen-enriching particles.

[0019] More preferably, in step (5.2), the pre-transport starvation and cooling pretreatment is performed as follows: individuals with intact bodies and active swimming are selected, starved for 48 hours before transportation, and ice packs are used for circulating cooling. The water temperature is gradually reduced from 28±1℃ to 21℃ at a rate of ≤2℃ / h, and the cooling rate is monitored and kept stable throughout the process.

[0020] Preferably, in step (5.2), the pre-transport starvation treatment involves feeding the last amount of food before stopping feeding at 65-75% of the normal amount, more preferably 70%.

[0021] More preferably, in step (5.3), the bagging density is optimized as follows: before sealing, the initial water temperature is set to 21℃, and the salinity is retested to be 5±1‰, the total alkalinity to be 3~4mmol / L, the dissolved oxygen to be 8~10mg / L, and the initial ammonia nitrogen to be <0.01mg / L. After the indicators meet the standards, the seedlings and water that have undergone starvation and cooling pretreatment are sealed in transparent bags, the transparent bags are placed in foam boxes and the temperature of the foam boxes is maintained at 21℃, the foam boxes are placed in transport vehicles, and the transportation vibration is simulated for 12 hours. The physiological state of the seedlings and the changes in the water are observed at regular intervals, and the optimal bagging density is obtained through screening.

[0022] Preferably, the transparent bag mentioned in step (5.3) is a transparent polyethylene bag.

[0023] More preferably, the optimal bagging density in step (5.3) is: 800 tails per bag for 2.2cm size and 600 tails per bag for 2.8cm size. This density combination performs best in terms of balancing space utilization and physiological tolerance.

[0024] Preferably, in step (5.5), 16 to 1 / 4 (more preferably 1 / 5) of the water volume of the aquaculture pond is added into the transparent bag, and the bag is left to stand for 8 to 12 seconds, more preferably 10 seconds.

[0025] Preferably, in step (5.5), when transferring the seedlings along with the mixed water to the breeding pond or net cage, mechanical damage should be avoided as much as possible during the operation, and dead individuals should be removed at the same time. After all the seedlings have been transferred, the lighting should be turned on to observe the overall condition, and no feed should be given on the same day.

[0026] The present invention has the following advantages: (1) The method of the present invention achieves efficient and healthy cultivation by precisely controlling key water quality parameters such as salinity, temperature, dissolved oxygen, and pH from hatching to juvenile stage at the seedling stage, combined with staged feeding and graded management. (2) The method of the present invention adopts a gradual desalination process to reduce the salinity of the aquaculture water to a low salinity (about 5‰) and stabilize it in a short period of time, thereby completing the salt and alkali tolerance acclimatization and adapting it to inland saline and alkali water bodies; (3) The present invention constructs a systematic long-distance transportation process at the transportation end, including pre-treatment of starvation and cooling before transportation, optimization of bag density and water conditions (water preparation: water is prepared according to the volume ratio of fresh water: seawater = 5:1, the salinity is adjusted to 5±1‰, the total alkalinity is stabilized at 3~4mmol / L, the dissolved oxygen is stabilized at 8~10mg / L, and the pH is tested and ensured to be 7.8~8.6 and ammonia nitrogen ≤0.01 mg / L before packaging), low temperature oxygenation and sealing, ice packs are put in to reduce vibration and maintain a low temperature environment, and temperature and water quality buffering and pooling operations after landing, etc. (4) The method of the present invention can effectively reduce the risk of stress and death during the journey, improve the survival rate and adaptability during long-distance transportation, and provide technical support for the large-scale breeding and cross-regional supply of barramundi in inland saline-alkali areas. It has good application prospects and economic value. Attached Figure Description

[0027] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0028] Figure 1 This is a flowchart of the salt-tolerant breeding and domestication method for barramundi fry and the long-distance transportation method in Embodiment 1 of the present invention. Detailed Implementation

[0029] The present invention will be further explained below with reference to the embodiments, but the embodiments do not limit the present invention in any way.

[0030] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0031] Unless otherwise specified, the experimental methods used in the following implementation methods are all conventional experimental methods.

[0032] Unless otherwise specified, the terms used in the following implementation methods and embodiments generally have the meanings commonly understood by those skilled in the art. Example 1

[0033] like Figure 1 As shown in this embodiment, the method for salt-tolerant breeding and long-distance transportation of barramundi fry includes the following steps: (1) Hatching of fertilized eggs: Hatching barramundi fertilized eggs in an incubation tank; This experiment was conducted at the Donghai Island Aquaculture Base of Guangdong Ocean University. In early May 2025, fertilized eggs were placed in clean incubation tanks. The incubation water was seawater (temperature 30℃, salinity 30‰, total alkalinity 3-4 mmol / L, dissolved oxygen controlled at 8-10 mg / L, temperature controlled at 28-31℃, dissolved oxygen controlled at 8-10 mg / L). During the incubation period, beaker samples were taken regularly to observe the molting and tail formation of the fertilized eggs, and the detached egg membranes on the water surface were cleaned up in a timely manner. (2) Hatching pond cultivation: The day after the fertilized eggs show their tails, they are moved to an outdoor hatching pond for breeding management. Breeding management includes breeding density, water quality control and feed feeding. When the seedlings grow to 0.7~0.8cm, they are moved to an indoor breeding pond. After the tail of the fertilized egg has formed (about 1 day), it is transferred to an outdoor hatching pond for breeding management, including breeding density, water quality control and feed feeding; The stocking density is 1600–2400 fish / m³; Water quality control includes: salinity of 30‰, total alkalinity of 3-4 mmol / L, temperature of 28-31℃, dissolved oxygen of 6-7 mg / L, pH of 7.6-8.2, ammonia nitrogen ≤0.3 mg / L, and nitrite ≤0.25 mg / L; Dissolved oxygen was measured using a portable dissolved oxygen meter; alkalinity was determined using acid-base titration; pH, ammonia nitrogen, and nitrite were measured using relevant reagent kits; water temperature was continuously monitored and recorded using a thermometer, the same applies below. Feeding includes: feeding rotifers at fixed points around the oxygen pump, twice a day at 8:00 and 15:00, with a feeding amount of 1.5-2% of the total fish weight. After feeding, observe the feeding status of the fry. After about 1 hour, take a sample with a beaker to check the amount of uneaten feed and adjust the subsequent feeding amount accordingly. When the fry grow to 0.7-0.8cm, they are transferred to indoor culture ponds. The temperature difference should be <2℃ and the salinity difference should be <5‰ when transferring the fry.

[0034] (3) Indoor culture pond cultivation: The initial water parameters of the indoor culture pond are consistent with those of the outdoor hatching pond, and the type and amount of starter feed are adjusted according to the growth process of the seedlings; The stocking density in indoor aquaculture ponds is 3200–4800 fish / m². 3 Feed them mainly with rotifers, supplemented with frozen worms and brine shrimp drip feed, 2-3 times a day, with the amount of feed being 1.5-2% of the total body weight of the fish. After feeding, observe feeding and uneaten feed, and adjust the feeding in time. Use a net to clean up uneaten feed on the water surface, and use a bottom suction device to remove bottom residue and metabolic waste. Turn off the aeration equipment during operation. During the breeding period, conduct feeding training with powdered feed every afternoon. Simultaneously, a feed transition was implemented, initially using 0.3 grade powdered feed. As the seedlings grew, they were periodically screened and graded, and seedlings of different sizes were transferred to breeding ponds with consistent breeding conditions. The feed particle size and formula were adjusted according to the feeding capacity and growth needs of seedlings of different sizes. If necessary, vitamin C feed additives were mixed into the feed to reduce stress and improve resistance. In response to the situation of insufficient feeding due to individual clustering in the early stage, in addition to fixed-point feeding, a small amount of feed was added in scattered areas, and frozen insects were fed by drip feeding to ensure that the seedlings at the bottom of the pond could also ingest feed.

[0035] (4) Gradual desalination and acclimatization: When the seedlings are 1.5cm long, seawater desalination begins. Fresh water is added to the culture pond. The salinity is gradually reduced and stabilized at 5‰±1‰ within 3-4 days, and the total alkalinity is stabilized at 3-4mmol / L. During the acclimatization process, the seedlings' swimming and feeding are observed regularly to ensure good vitality and no abnormal stress. The seedlings are considered to have completed salinity and alkalinity acclimatization when they are healthy and stable in water with a salinity of 5‰±1‰ and a total alkalinity of 3-4mmol / L.

[0036] The specific operation includes: continuously and slowly replenishing freshwater to the aquaculture pond from 7:00 to 15:00 every day, controlling the daily salinity drop to ≤8‰, and using an optical salinity meter (sampling depth about 30 cm below the water surface) to detect salinity at 7:00 and 15:00 every day. After 3 to 4 adjustment cycles, the salinity is stabilized to 5‰±1‰ and the total alkalinity is 3 to 4 mmol / L.

[0037] In steps (2) to (4), the fry are regularly screened and graded according to the difference in body length and weight. The fry of different sizes are raised in separate ponds. The water quality parameters of the new pond are kept consistent with those of the original pond. The grading is carried out every 3 to 5 days. If there is obvious cannibalism, feeding should be stopped first. After feeding is stopped, screening is carried out 8 to 12 hours later. The fry of different sizes are transferred to different net cages or aquaculture ponds. After the grading is completed, the povidone-iodine solution is diluted with water according to the ratio and evenly sprinkled to reduce stress and disinfect the water. If obviously large individuals or cannibalism are found during daily pond inspections, grading should be carried out immediately.

[0038] During the entire aquaculture cycle in steps (2) to (4), daily water quality testing is carried out. The water quality testing indicators include dissolved oxygen, transparency, pH, alkalinity and ammonia nitrogen. At the same time, the water temperature is controlled at 27-32℃. When the transparency is low or the pH is <7.2, photosynthetic bacteria are added to the water to improve the water quality and micro-ecology. When ammonia nitrogen >0.1 mg / L or nitrite >0.3 mg / L, the corresponding water quality control reagents are added in time for treatment.

[0039] In steps (2) to (4), the daily feeding amount is determined according to the total mass of the fish in the pond. The feeding method is adopted twice a day, and the total amount is about 1.5% of the total mass of the fish. While meeting the metabolic needs, the water quality is avoided from deteriorating. The type of feed is matched with the growth stage: powdered feed is used to promote feeding and acclimatization during the seedling stage, and high-protein extruded feed (crude protein 50% to 60%) is used to promote rapid growth during the juvenile stage. Electrolyte multivitamins are added to the feed, mainly vitamin C (L-ascorbic acid-2-phosphate) to enhance stress resistance and immune function.

[0040] (5) Conduct long-distance transportation simulation tests: Simulated transport experiments were conducted on juvenile fish measuring 2.2cm and 2.8cm to determine recommended parameters: (5.1) Water preparation: Prepare water at a volume ratio of fresh water to seawater of 5:1, adjust the salinity to 5‰±1‰, stabilize the total alkalinity at 3-4 mmol / L, stabilize the dissolved oxygen at 8-10 mg / L, and test and ensure that the pH is 7.8-8.6 and the ammonia nitrogen is ≤0.01 mg / L before packaging; Specifically, the process includes: preparing water at a freshwater to seawater volume ratio of 5:1, thoroughly mixing the mixture, using a salinity meter to precisely correct the salinity to 5‰±1‰ and the alkalinity to 3-4 mmol / L, continuously aerating the water with aeration equipment to stabilize dissolved oxygen at 8-10 mg / L, adding oxygen-enriching granules to the pretreated water at a standard of 1-2 granules / bag, and then finely filtering to remove suspended impurities to ensure the water is clear.

[0041] (5.2) Pre-treatment of starvation and cooling before transportation: Select individuals with intact bodies and active swimming, starve them for 48 hours before transportation (the last feeding amount before stopping feeding is 70% of the normal amount), and use an ice pack circulating cooling system to gradually reduce the water temperature from 28±1℃ to 21℃ at a rate of ≤2℃ / h, and monitor and maintain a stable cooling rate throughout the process. The specific pre-transport starvation treatment includes: selecting juvenile fish with no external injuries and active swimming from the breeding pond and placing them in a special starvation treatment pond for 48 hours of starvation treatment, that is, reducing the last feeding amount before stopping feeding to 70% of the normal amount to reduce the stress of sudden fasting. During the starvation period, observe swimming speed and changes in body color at regular intervals every day. If any abnormalities such as slow swimming or dull body color occur, immediately remove them and return them to the breeding net cage. At the same time, investigate potential causes such as water quality or disease. The cooling pretreatment specifically includes: using an ice pack circulation cooling system, evenly distributing ice packs around the container, and gradually reducing the water temperature from 28±1℃ to 21℃ through heat exchange at a rate of ≤2℃ / h. The temperature is continuously monitored with a thermometer throughout the process to ensure a stable cooling rate and avoid stress caused by cooling too quickly or too slowly. After the temperature drops to 21℃, it is maintained for a period of time to allow the juvenile fish to fully adapt.

[0042] (5.3) Optimization of bag density: Before packaging, the initial water temperature was set to 21℃. The salinity was measured again to be 5‰±1‰, the total alkalinity was 3~4mmol / L, the dissolved oxygen was 8~10mg / L, and the initial ammonia nitrogen was <0.01mg / L. After the indicators met the standards, the seedlings and water that had been pretreated by starvation and cooling were packaged in transparent bags. The transparent bags were placed in foam boxes and the temperature of the foam boxes was maintained at 21℃. The foam boxes were placed in transport vehicles to simulate transportation vibration for 12 hours. The physiological state of the seedlings and the changes in the water were observed regularly. After screening, 2.2cm size was obtained with 800 fish / bag and 2.8cm size with 600 fish / bag. This density combination performed best in terms of balancing space utilization and physiological tolerance. Bag density optimization specifically includes: Three density gradients were set up, each containing juvenile fish of two sizes: 2.2cm and 2.8cm. Experimental group 1 contained 1200 fish / bag (2.2cm) and 1000 fish / bag (2.8cm); Experimental group 2 contained 1000 fish / bag (2.2cm) and 800 fish / bag (2.8cm); Experimental group 3 contained 800 fish / bag (2.2cm) and 600 fish / bag (2.8cm).

[0043] 4 L transparent polyethylene bags were used for packaging, ensuring that each bag contained a uniform 4 L of water. Before packaging, salinity (5‰±1‰), total alkalinity (3~4mmol / L), pH (7.8~8.6), and ammonia nitrogen (≤0.01mg / L) were retested. Once the indicators met the standards, the bags were packaged and neatly placed into a foam box. Appropriate ice packs were evenly distributed around the sides and top of the foam box to ensure uniform temperature distribution inside the box and to avoid direct contact with the seedling packaging bags to prevent frostbite. Simultaneously, the foam box was placed in a transport vehicle to simulate 12 hours of transport vibration. The physiological state of the juvenile fish (swimming activity, number and duration of side-turning, floating phenomenon, etc.) and water changes (turbidity, sedimentation of impurities at the bottom of the bag, etc.) were observed regularly, and records were taken every 2 hours. In this embodiment, the initial water temperature was set at 21℃, salinity at 5‰, total alkalinity at 3-4 mmol / L, dissolved oxygen at 8.2-8.6 mg / L, and initial ammonia nitrogen at <0.01 mg / L. Based on 12 hours of continuous monitoring data, experimental group 3 (800 fish / bag for 2.2cm and 600 fish / bag for 2.8cm) showed the best overall performance (as shown in Tables 1-2): the number of juvenile fish rolling over and dying was extremely low, the water was clear with no obvious sediment, the grouping behavior was stable, and no significant stress response was observed. This density combination showed the best performance in balancing space utilization and physiological tolerance, and can be used as the preferred parameter for bagging density in actual long-distance air transport.

[0044] Table 1. Statistical table of mortality data for each experimental group in the simulated transportation test (2.2cm specification). Note: The data below each time point in the table represent the total number of rollovers and deaths for the three groups from the start of treatment to that time point. When the number exceeds 200, it is considered that the density is unsuitable for transporting juvenile fish, and subsequent experiments should be stopped.

[0045] Table 2. Statistics of mortality data for each experimental group in the simulated transportation test (2.8cm specification). Note: The data below each time point in the table represent the total number of rollovers and deaths for the three groups from the start of treatment to that time point. When the number exceeds 200, it is considered that the density is unsuitable for transporting juvenile fish, and subsequent experiments should be stopped.

[0046] (5.4) Low temperature oxygenation sealing and transportation: The seedlings that have undergone starvation and cooling pretreatment are bagged according to the parameters selected in step (5.3), the air in the bag is removed, oxygen is added and sealed to maintain a low temperature environment, and the seedlings are transported by air to the destination airport. After receiving the goods, they are transported to the breeding farm by refrigerated truck and prepared for entry into the pond. Specifically, the following measures were taken: juvenile fish with smooth skin, no external injuries, no pathological symptoms (no white spots, red spots, etc.), swimming freely and responding sensitively to stimuli were selected as the transport targets. The transport time was July 20, 2025. The transport quantity was 16,700 fish of 2.2cm size and 10,200 fish of 2.8cm size, totaling 26,900 fish. The fish were packaged according to the optimal packing density parameters obtained in (5.3). After starvation and cooling treatment according to the simulated transport test process in (5.2), the fish were packed into transparent plastic bags (preferably made of polyethylene) according to the optimal density based on their size. When bagging, gently press the bag to expel most of the air, then oxygenate it and tie the bag opening tightly with rubber bands or ropes to ensure a good seal. After sealing, check each bag for damage or leakage. Place the bags into a foam box, fill the sides and top with ice packs to maintain a low temperature environment, clearly mark the size of the juvenile fish on the outside of the foam box, and seal and secure the box with tape or other materials to prevent it from being opened during transportation. Use a dedicated air freight outer box to ensure that it can accommodate and effectively protect the foam box. Securely place the sealed foam box into the outer box and fix it to prevent displacement during transit and transportation.

[0047] (5.5) Temperature and water quality buffering after landing: After long-distance transportation, the seedlings arrive at the saline-alkali water aquaculture base. The salinity of the saline-alkali water aquaculture base is adjusted to 5‰±1‰, the total alkalinity to 4mmol / L±1mmol / L, and the temperature to 25℃±1℃. The transparent bag is first used to balance the temperature, and then the aquaculture pond water is added into the transparent bag. After the seedlings adapt to the water quality change, the seedlings and the mixed water are transferred to the aquaculture pond or net cage. Specifically, the process involves: after approximately 17 hours of long-distance transportation, the packaged fish arrives at the saline-alkali water aquaculture base in Toksun County, Xinjiang (salinity 5‰±1‰, total alkalinity 4mmol / L±1mmol / L, 25℃±1℃). Upon arrival, the packaged bags are floated on the surface of the pre-prepared aquaculture pond for approximately 30 minutes to allow for temperature equilibration. During this time, the bags can be gently shaken to promote temperature equalization between the inside and outside of the water. After temperature equilibration, aquaculture pond water is slowly added to the packaged bags, approximately 1 / 5 of the bag's volume. The bags are then left to stand for about 10 seconds to allow the juvenile fish to adapt to the water quality change. Once this has happened, the juvenile fish, along with the mixed water, are gently transferred to the aquaculture pond or net cage. During this process, mechanical damage should be avoided as much as possible, and any dead individuals should be removed simultaneously. After all fish were transferred, the lights were turned on to observe their overall condition. No feed was given on the same day. The first inspection was completed within 2 hours after the transfer. The dead fish were collected and the number of dead fish was counted the next morning. The survival rate of the two sizes was calculated separately (survival rate = number of surviving fish / initial number × 100%). The specific statistical results are shown in Table 3: the survival rate of the two sizes of fry exceeded 99%. The fish had smooth bodies, no external injuries, stable group behavior, no significant stress response, and good vitality. The fry were transported over long distances effectively.

[0048] Table 3. Survival statistics of juvenile barramundi during long-distance transportation (July 20, 2025) Fish fry size (cm) Transportation time (h) Number of shipments (tails) Death count (tail) Survival rate during transportation (%) 2.20 17 (4:00 am - 9:00 pm) 16700 0 100 2.80 17 (4:00am-9:00pm) 10200 16 99.84 Example 2

[0049] The selection criteria for transported fish are the same as in Example 1, namely, juvenile fish with smooth skin, no external injuries, no disease symptoms (such as no white spots, red spots, etc.), swimming freely and responding sensitively to stimuli.

[0050] The transportation date is July 28, 2025, and the quantities transported are: 13,000 tails of the 2.2cm size and 14,000 tails of the 2.8cm size. Based on the simulated transportation results of Example 1, this transportation directly adopts the third set of optimal bagging density parameters (800 tails / bag for 2.2cm and 600 tails / bag for 2.8cm) for the 2.2cm and 2.8cm sizes, following the principles of low density and safety priority in bagging. The operation procedure is the same as in Example 1: after completing 48 hours of starvation treatment and gradient cooling according to the size, the tails are packed into transparent plastic bags at the determined density, most of the air inside the bags is expelled, oxygen is added and the bags are sealed, and the sealing and integrity of each bag are checked; the bags are placed in foam boxes filled with ice packs to maintain low temperature, the outer box is clearly marked with the size and sealed and fixed; air transport is used to transfer the goods to the destination airport.

[0051] After approximately 17 hours of long-distance transportation to the aquaculture farm (salinity 5‰±1‰, total alkalinity 4mmol / L±1mmol / L, 25℃±1℃), the packaging bags were floated on the surface of the aquaculture pond for about 30 minutes to achieve temperature equilibration. Then, aquaculture pond water (approximately 1 / 5 of the bag's volume) was slowly added into the bags. After settling for about 10 seconds, the fry, along with the mixed water, were gently released into the aquaculture unit. During this process, any dead individuals were removed to avoid mechanical damage. The fry were not fed on the day of arrival. The first inspection was conducted within 2 hours of release into the pond. The number of dead fry was counted the following morning, and the survival rate was calculated (survival rate = number of surviving fry / initial number × 100%). Specific data are shown in Table 4: the survival rate of both 2.2cm and 2.8cm fry exceeded 99%. The fry exhibited smooth bodies, no external injuries, stable schooling behavior, no significant stress response, and good vitality, demonstrating good long-distance transport performance.

[0052] Table 4. Survival Statistics of Juvenile Barramundi During Long-Distance Transportation (July 28, 2025) Fish fry size (cm) Transportation time (h) Number of shipments (tails) Death count (tail) Survival rate during transportation (%) 2.2 17 (3:00am-20:00pm) 13000 14 99.89 2.8 17 (3:00am-20:00pm) 14000 46 99.67 Therefore, the method for salt-alkali acclimatization and long-distance transportation of barramundi fry provided by this invention covers the entire process from fertilized egg hatching, fry rearing, graded management, and gradual desalination acclimatization, enabling fry to grow stably in low-salinity saline-alkali waters. Simultaneously, it constructs a refined long-distance transportation process, reducing stress during transit and improving survival rate and adaptability upon arrival through measures such as optimized bagging density, dissolved oxygen and temperature gradient control, and starvation and cooling pretreatment. This technology achieves efficient transfer and local acclimatization of barramundi fry from production areas to remote saline-alkali regions, improving the availability of saline-alkali water resources, expanding the aquaculture area, and supporting market expansion.

[0053] The above embodiments are merely examples illustrating the technical solutions of the present invention and are not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A method for salt-tolerant culture and domestication of barramundi juveniles and for long-distance transportation, characterized in that, Includes the following steps: (1) Hatching of fertilized eggs: Hatching barramundi fertilized eggs in an incubation tank; (2) Hatching pond cultivation: The day after the fertilized eggs show their tails, they are moved to an outdoor hatching pond for breeding management. Breeding management includes breeding density, water quality control and feed feeding. When the seedlings grow to 0.7~0.8cm, they are moved to an indoor breeding pond. (3) Indoor culture pond cultivation: The initial water parameters of the indoor culture pond are consistent with those of the outdoor hatching pond, and the type and amount of starter feed are adjusted according to the growth process of the seedlings; (4) Gradual desalination and acclimatization: When the seedlings are 1.4-1.6 cm long, seawater desalination begins. Fresh water is added to the culture pond. The salinity is gradually reduced and stabilized at 5‰±1‰ within 3-4 days, and the total alkalinity is stabilized at 3-4 mmol / L. During the acclimatization process, the seedlings' swimming and feeding are observed regularly to ensure good vitality and no abnormal stress. The seedlings are considered to have completed salinity and alkalinity acclimatization when they are healthy and stable in water with a salinity of 5±1‰ and a total alkalinity of 3-4 mmol / L. (5) Conduct long-distance transportation simulation tests: (5.1) Water preparation: Prepare water at a volume ratio of fresh water to seawater of 4 to 6 to 1, adjust the salinity to 5 ± 1‰, stabilize the total alkalinity at 3 to 4 mmol / L, stabilize the dissolved oxygen at 8 to 10 mg / L, and test and ensure that the pH is 7.8 to 8.6 and the ammonia nitrogen is ≤0.01 mg / L before packaging; (5.2) Starvation and cooling pretreatment before transportation: Select individuals with intact bodies and active swimming. Starve them for 46-50 hours before transportation. Use ice packs to circulate and cool them down. Gradually reduce the water temperature from 28±1℃ to 21±1℃ at a rate of ≤2℃ / h. Monitor the temperature throughout the process and keep the cooling rate stable. (5.3) Optimization of bag density: Before packaging, the initial water temperature was set to 21±1℃. The salinity was retested to 5±1‰, the total alkalinity to 3~4mmol / L, the dissolved oxygen to 8~10mg / L, and the initial ammonia nitrogen to <0.01mg / L. After the indicators met the standards, the seedlings and water that had undergone starvation and cooling pretreatment were packaged in transparent bags. The transparent bags were placed in foam boxes and the temperature of the foam boxes was maintained at 21±1℃. The foam boxes were placed in transport vehicles to simulate transportation vibration for 11~13 hours. The physiological state of the seedlings and changes in the water were observed regularly. After screening, the bag density was obtained as follows: 2.2~2.8cm, 600~800 fish per bag. (5.4) Low temperature oxygenation sealing and transportation: The seedlings that have undergone starvation and cooling pretreatment are bagged according to the water prepared in step (5.1) and the parameters selected in step (5.3). After the air in the bag is exhausted, oxygen is added and sealed to maintain a low temperature environment. The seedlings are transported by air to the destination airport. After receiving the goods, they are transported to the breeding farm by refrigerated truck and prepared for entry into the pond. (5.5) Temperature and water quality buffering after landing: After long-distance transportation, the seedlings arrive at the saline-alkali water aquaculture base. The salinity of the saline-alkali water aquaculture base is adjusted to 5±1‰, the total alkalinity to 4±1mmol / L, and the temperature to 25±1℃. The transparent bag is first used to balance the temperature, and then the aquaculture pond water is added into the transparent bag. After the seedlings adapt to the water quality change, the seedlings and the mixed water are transferred to the aquaculture pond or net cage.

2. The method for salt-tolerant culture and long-distance transportation of barramundi fry according to claim 1, characterized in that, In step (1), when hatching barramundi fertilized eggs in the hatching tank, the hatching water is seawater with a salinity of 30‰ and a total alkalinity of 3-4 mmol / L. The temperature is controlled at 28-31℃ and the dissolved oxygen is controlled at 8-10 mg / L. During the hatching period, the molting of the fertilized eggs is observed regularly and the floating egg membrane is cleaned.

3. The method for salt-tolerant culture and long-distance transportation of barramundi fry according to claim 1, characterized in that, In step (2), the fertilized eggs are transferred to the hatching pond the day after the tail of the fish appears. When the fry are introduced into the pond, the temperature difference is <2℃ and the salinity difference is <5‰.

4. The method for salt-tolerant culture and long-distance transportation of barramundi fry according to claim 1, characterized in that, In step (2), the stocking density is 1600–2400 fish / m². 3 Water quality control in the hatching pond includes: salinity of 30‰, total alkalinity of 3-4 mmol / L, temperature of 28-31℃, dissolved oxygen of 6-8 mg / L, pH of 7.6-8.2, ammonia nitrogen ≤0.3 mg / L, and nitrite ≤0.25 mg / L. Feeding includes feeding rotifers at fixed points around the oxygen pump twice a day, at 8:00 and 15:00, with a feeding amount of 1.5-2% of the total fish mass. After feeding, observe the feeding status of the fry, take samples to check the amount of uneaten feed, and adjust the subsequent feeding amount accordingly. After the fry grow to 0.7-0.8 cm, they are transferred to indoor rearing ponds. The temperature difference during transfer should be <2℃ and the salinity difference should be <5‰.

5. The method for salt-tolerant culture and long-distance transportation of barramundi fry according to claim 1, characterized in that, In step (3), the stocking density in the indoor culture pond is 3200–4800 fish / m². 3 Feed them mainly with rotifers, supplemented with frozen worms and brine shrimp drip feed, 2-3 times a day, with the amount of feed being 1.5-2% of the total body weight of the fish. After feeding, observe feeding and uneaten feed, and adjust the feeding in time. Use a net to clean up uneaten feed on the water surface and use a bottom suction device to remove the residue at the bottom. Turn off the aeration equipment during operation. During the breeding period, conduct feeding training with powdered feed every afternoon.

6. The method for salt-tolerant culture and long-distance transportation of barramundi fry according to claim 1, characterized in that, In step (3), feed transition is carried out. Initially, 0.3 type powdered feed is used. As the seedlings grow, they are periodically screened and graded. Seedlings of different sizes are transferred to breeding ponds with consistent breeding conditions. The feed particle size and formula are adjusted according to the feeding ability and growth needs of seedlings of different sizes. If necessary, vitamin C feed additives are mixed into the feed to reduce stress and improve resistance. In case of insufficient feeding in the early stage of individual grouping, in addition to fixed-point feeding, a small amount of feed is added in a small scattered area. Frozen insects are fed by drip feeding to ensure that the seedlings at the bottom of the pond can also ingest feed.

7. The method for salt-tolerant culture and long-distance transportation of barramundi fry according to claim 1, characterized in that, In steps (2) to (4), the seedlings are regularly screened and graded according to the difference in body length and weight. The seedlings of different sizes are raised in separate ponds. The water quality parameters of the new pond are kept consistent with those of the original pond. The seedlings are graded every 3 to 5 days. If there is obvious cannibalism, feeding is stopped first. After feeding is stopped, screening is carried out 8 to 12 hours later. The seedlings of different sizes are transferred to different net cages or aquaculture ponds. After grading, the povidone-iodine solution is diluted with water according to the ratio and evenly sprinkled to reduce stress and disinfect the water.

8. The method for salt-tolerant culture and long-distance transportation of barramundi fry according to claim 1, characterized in that, During the entire aquaculture cycle in steps (2) to (4), daily water quality testing is carried out. The water quality testing indicators include dissolved oxygen, transparency, pH, alkalinity and ammonia nitrogen. At the same time, the water temperature is controlled at 27-32℃. When the transparency is low or the pH is <7.2, photosynthetic bacteria are added to the water to improve the water quality and micro-ecology. When ammonia nitrogen >0.1mg / L or nitrite >0.3mg / L, the corresponding water quality control reagents are added in time for treatment.

9. The method for salt-tolerant culture and long-distance transportation of barramundi fry according to claim 1, characterized in that, Steps (2) to (4) also include nutritional fortification: the daily feeding amount is determined according to the total mass of the fish in the pond, and the feeding method is adopted twice a day at fixed times, with a total amount of 1.2 to 1.8% of the total mass of the fish. While meeting the metabolic needs, water quality deterioration is avoided. The type of feed is matched with the growth stage: powdered feed is used to promote feeding and acclimatization during the seedling stage, and high-protein extruded feed is used to promote rapid growth during the juvenile stage. Electrolyte multivitamins are added to the feed, with vitamin C as the main component, to enhance stress resistance and immune function.

10. The method for salt-tolerant culture and long-distance transportation of barramundi fry according to claim 1, characterized in that, In step (5.1), oxygen-enriching granules are also provided; in step (5.2), the pre-transport starvation treatment involves feeding the last amount of food before stopping feeding at 65-75% of the normal amount; in step (5.3), the transparent bag is a transparent polyethylene bag; in step (5.3), the optimal bagging density is: 800 fish per bag for 2.2cm size and 600 fish per bag for 2.8cm size. This density combination performs best in terms of balancing space utilization and physiological tolerance; in step (5.5), water from the aquaculture pond is added to the transparent bag, accounting for 1 / 6 to 1 / 4 of the water volume in the bag, and left to stand for 8-12 seconds; in step (5.5), when transferring the seedlings along with the mixed water to the aquaculture pond or net cage, mechanical damage should be avoided as much as possible during the operation, and dead individuals should be removed simultaneously. After all the transfers are completed, the lighting should be turned on to observe the overall condition, and no feed should be given on the same day.

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