Land-sea relay high-efficiency low-stress transfer method for mackerel fry

Abstract

The invention relates to the technical field of fry transfer, in particular to a land-sea relay high-efficiency low-stress transfer method for mackerel fry. The method comprises the steps of transferring from a nursery pond to a fry collecting pond, intelligently counting fries and transferring in water, conveying the fries to a fry conveying box, conveying the fries to a transport vehicle on a land track, transferring the fries to the transport vehicle through a crane and transferring the fries to a wharf and sea, and finally putting the fries into a net cage through a transport ship. In the transfer process, a buffer discharge pipeline and an underwater conveying system are utilized, and independent circulating water and liquid oxygen supply systems of an intelligent counting machine and a fry conveying box are combined, so that the fries are always in a stable water environment, mechanical damage can be avoided, stress caused by sudden change of the environment is reduced, meanwhile, all links are efficiently and cooperatively operated, and the transfer efficiency of the fries is improved. The problem of high death rate caused by mechanical injury, environmental mutation and stress reaction in the transfer process of the fries is fundamentally solved, so that the survival rate of the fries is increased, and the breeding production is smoothly carried out.

Description

Technical Field

[0001] The present invention relates to the technical field of fry transportation, and specifically, to a method for efficient and low-stress land-sea relay transportation of Eleutheronema tetradactylum fry. Background Art

[0002] Eleutheronema tetradactylum, commonly known as horse mackerel, is an euryhaline fish widely distributed in tropical and subtropical waters. Due to its rapid growth and delicious meat, it has become an important aquaculture variety in the southern coastal areas of China. In recent years, with the breakthrough of artificial breeding technology, large-scale aquaculture of Eleutheronema tetradactylum has been achieved. For example, the South China Sea Fisheries Research Institute of the Chinese Academy of Fishery Sciences successfully completed the research on the technology of full artificial reproduction and fry cultivation of Eleutheronema tetradactylum in 2015, and cultivated a large number of healthy fry. However, Eleutheronema tetradactylum fry are extremely vulnerable to stress reactions during transportation, resulting in high mortality, which severely restricts the development of the aquaculture industry. The existing transportation methods mainly rely on oxygen-filled plastic bag transportation, but this method has many drawbacks, such as fry being easily damaged mechanically, the dissolved oxygen being difficult to maintain continuously, and the water temperature being difficult to control during transportation. All these affect the survival rate of Eleutheronema tetradactylum fry. In addition, fry may secrete a large amount of mucus due to stress reactions during transportation, further increasing the mortality rate. In response to these problems, the South China Sea Fisheries Research Institute proposed a method for factory farming of Eleutheronema tetradactylum, using artificially prepared seawater and a closed-circuit water system for farming. This method has solved the problem of environmental control during the farming process to a certain extent, but for the transportation link of fry, there is still a lack of effective low-stress solutions, and the problem of high mortality of fry caused by mechanical damage, environmental mutation and stress reactions during transportation has not been fundamentally solved.

[0003] In view of this, there is an urgent need for a method for efficient and low-stress land-sea relay transportation of Eleutheronema tetradactylum fry. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for efficient and low-stress land-sea relay transportation of Eleutheronema tetradactylum fry that can effectively reduce the stress reaction of fry during transportation, improve the survival rate, and ensure the smooth progress of aquaculture production, so as to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides a method for efficient and low-stress land-sea relay transportation of Eleutheronema tetradactylum fry, including the following steps: S1. Transfer from the seedling rearing pond to the seedling collection pond: In the seedling rearing ponds of an industrialized seedling rearing workshop with a length of 47 m and a width of 17 m, there are 20 seedling rearing ponds with a length of 6 m, a width of 3.5 m, and a depth of 1.5 m. A passage with a width of 2 m and a length of 47 m is set in the middle of the 20 seedling rearing ponds; since the distance from the seedling rearing pond to the seedling collection pond is only 50 cm, it is necessary to lower the water level in the seedling rearing pond to 55 cm - 65 cm, pull out the 6-inch plastic pipes inserted at the bottom of the seedling rearing pond, and smoothly discharge and transport the fry to the seedling collection pond through the preset sewage discharge pipeline; one seedling collection pond is set for every two ponds on the left and two ponds on the right in the passage. The fry flows into the seedling collection net box in the seedling collection pond (a switch is set at the bottom to control the flow rate) through the pipe orifice; the sewage discharge pipeline is provided with a buffer section and a flow rate regulating device to control the smoothness of the water flow, reduce the stress of the fry caused by the impact, and enable the fry to transfer from the closed seedling rearing environment to the relatively open seedling collection pond under the condition of the smallest environmental change; S2. Intelligent counting of fry and in-water transfer: Use a water basin device to collect the fry in the seedling collection net box. The water basin device is of a closed structure and has an inclined bottom, so that the fry is always in the water to avoid stress reactions caused by being out of water. The collected fry is smoothly and evenly introduced into an intelligent counting machine for automatic counting operations. The intelligent counting machine integrates a machine vision system with a 2000 fps high-speed camera at the end of the diversion pipe. Using image recognition technology and high-precision counting software, dynamic counting is realized, and the error rate is <0.5%, and the number of fry is recorded in real time and accurately; S3. Transport fry to the fry transport box: The counted fry directly flow into the fry transport box through the transport pipeline. There is an overflow port 15 cm above the top of the fry transport box, which is used for fish-water separation and controlling the water level in the fry transport box. The specifications of the fry transport box are 1.25 m in length, 0.8 m in width, and 1 m in height. Its outer layer (support layer) is made of carbon fiber reinforced resin (CFRP), the middle layer is a bio-based closed-cell foam material, and the inner layer (water bag) is a multi-layer composite high-strength flexible material. It is also equipped with an independent circulating water system and a liquid oxygen supply system, and integrates the interface of the central liquid oxygen supply system. The transport pipeline is equipped with a buffer and diversion system, which consists of a flexible or rigid pipeline with a smooth inner wall and a diameter of 10 - 20 cm, and at the same time, a gas source system composed of a low-pressure blower or air compressor with a combined pressure < 0.1 MPa, a mixing chamber for mixing fry and water, a fish-water separation device at the transport terminal, and a control unit that can adjust the air flow speed and pulse frequency. Among them, in the mixing chamber, the fry and water form a suspension according to a volume ratio of 3:1 - 5:1, and a buffer agent of 0.1 kg / m³ - 0.3 kg / m³ is added to reduce the friction between fish bodies and between fish bodies and the pipe wall. Subsequently, the low-pressure air flow generated by the low-pressure blower or air compressor is injected from the bottom or side of the transport pipeline at a speed of 6 m / s - 12 m / s, generating the Venturi effect, driving the fish-water mixture to form a segmented plug flow (non-continuous full pipe flow), so that the fry is always wrapped by the water medium, avoiding direct friction with the pipe wall. The fish-water mixture is pulsed and advanced at 2 - 4 pulses per second. At this time, the fry moves in a spiral forward trajectory in the pipeline, with an average transport speed of 0.8 m / s - 1.2 m / s. When the fish-water mixture enters the fish-water separation device, the fish and water are automatically separated through an inclined screen. The separated water can be recycled after filtration. The fry remains in a low-stress state during transportation, without being affected by severe jolts or sudden temperature changes; S4. Transport by land rail to the transport vehicle: The fry transport box is equipped with an automatic identification label and positioning system, enabling the fry transport box to be accurately identified and positioned. Subsequently, the fry transport box is transported to the loading area of the special fry transport vehicle by the rail handling system. The rail system is driven by an automatic navigation and precise positioning module, ensuring the stable and accurate movement of the fry transport box during handling. Among them, there are two specifications for the special fry transport vehicle, namely an 8-box vehicle with a length of 7 m and a 16-box vehicle with a length of 14 m. It has an automatic opening and closing function for the top cover, facilitating the loading and unloading of the fry transport box. It is also equipped with an intelligent temperature control system to regulate the temperature inside the vehicle to meet the temperature requirements of the fry. At the same time, it is equipped with a central liquid oxygen supply system to continuously provide sufficient oxygen for the fry and provide a survival environment. In addition, there is a video observation system to facilitate observing the state of the fry inside the vehicle at any time; S5. Crane transfer to transport vehicle and then to the dock and marine transfer: In the loading area of the transport vehicle, use a crane device equipped with a variable-speed intelligent control system to automatically lift the seedling transport box from the rail to the transport vehicle. The crane operates at a slow speed and smoothly throughout the process to prevent stress in the fry caused by sudden stops or rapid vibrations. After loading, the transport vehicle drives to the dock, and the dock crane is used to directly lift the seedling transport box onto the deck of the transport ship; S6. Final release of the transport ship to the net cage: After the transport ship sails to the modern ocean ranch, use the crane on the ship to invert and introduce the fry in the seedling transport box into the pre-arranged net cage with a knotless sieve net structure with a mesh size of 5 meshes. The net cage has a water circulation and can effectively isolate external pollution to prevent the escape of fry.

[0006] In the present invention, first, by using a buffer discharge pipeline and a water conveyance system, the fry can have a continuous supply of water environment throughout the process from the nursery pond to the seedling collection box, which not only effectively reduces the stress response of the fry caused by mechanical shock and water flow fluctuations, allows the fry to transition in a stable water environment, and reduces the stimulation brought by environmental changes; at the same time, a special conveyance pipeline is used in combination with an automatic diversion and buffer system to safely convey the fry from the intelligent counting system to the seedling collection box. For example, the buffer diversion system in the conveyance pipeline can achieve a stable conveyance environment by controlling the flow rate change; it can also effectively improve the comfort of the fry during the entire conveyance process, keep the factors of temperature, flow rate, and vibration in the environment where the fry is located at the optimal state, further reduce the stress level of the fry, and improve the survival rate of the fry.

[0007] Compared with the prior art, the beneficial effects of the present invention: 1. In this method for the efficient and low-stress land-sea relay transfer of four-finger threadfin fry, through measures such as setting up a buffer diversion system and configuring intelligent equipment in each link of the transfer, the effect of effectively reducing the stress response of the fry is achieved; during the transfer process, by using a buffer discharge pipeline and a water conveyance system, combined with an intelligent counting machine and the independent circulating water and liquid oxygen supply system of the seedling transport box, not only can the fry always be in a stable water environment, avoiding mechanical damage, but also some environmental factors such as water quality, temperature, and dissolved oxygen can be controlled, reducing stress caused by sudden environmental changes. At the same time, the fully automated rail, crane, and intelligent monitoring system realize the acquisition and regulation of real-time water quality, temperature, flow rate, and vibration data, and each link operates efficiently and cooperatively, avoiding the problems of difficult maintenance of dissolved oxygen and difficult control of water temperature in traditional plastic bag oxygenation transportation, fundamentally solving the problem of high mortality rate of fry caused by mechanical damage, sudden environmental changes, and stress response during the transfer process, thereby improving the survival rate of fry and enabling the smooth progress of aquaculture production.

[0008] 2. In the method for efficient and low-stress land-sea relay transportation of four-finger Spanish mackerel fry, by adopting the whole-process low-stress transportation process and the structural design of the buffer diversion system, seamless connection of all links from the nursery pond to the marine ranch and continuous and stable control of the water environment are not only achieved, enabling the fry to always be in a low-stress state and reducing the harm to the fry caused by uneven stress generated by water flow impact and mechanical vibration; but also with the precise counting of the intelligent counting machine, as well as some functions such as the independent circulating water and liquid oxygen supply system of the fry transportation box and the intelligent temperature control, liquid oxygen supply, and video observation of the special fry transport vehicle, a stable and suitable living environment is provided for the fry. At the same time, the buffer diversion channel and multi-section partition design inside the fry collection box regulate the flow rate, reducing the vibration and collision risks of the fry during transportation, thereby improving the survival rate of the fry. Brief Description of the Drawings

[0009] Figure 1 It is a flow chart of the method for efficient and low-stress land-sea relay transportation of four-finger Spanish mackerel fry of the present invention. Detailed Embodiment

[0010] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention. Embodiment 1

[0011] In the nursery pond of the industrialized nursery workshop with a length of 47 m and a width of 17 m, 20 nursery ponds with a length of 6 m, a width of 3.5 m, and a depth of 1.5 m are provided. A passage with a width of 2 m and a length of 47 m is arranged in the middle of the 20 nursery ponds; the water level in the nursery pond is lowered to 60 cm, and the 6-inch plastic pipe inserted into the bottom of the nursery pond is pulled open, and the fry are smoothly discharged and transported to the fry collection pond through the preset sewage discharge pipe; one fry collection pond is set in a group with 2 ponds on the left and 2 ponds on the right in the passage, and the fry flow into the fry collection net box in the fry collection pond (a switch is set at the bottom to control the flow rate) through the pipe orifice; the sewage discharge pipe is provided with a buffer section and a flow rate control device to control the smoothness of the water flow and reduce the stress of the fry caused by the impact, so that the fry are transferred from the closed nursery environment to the relatively open fry collection pond under the condition of the smallest environmental change; After that, a water basin device is used to collect the fry in the fry collection net box. The water basin device is of a closed structure and the bottom is inclined, so that the fry are always in the water to avoid stress reactions caused by leaving the water. The collected fry are smoothly and evenly introduced into the intelligent counting machine for automatic counting operations. The intelligent counting machine integrates a machine vision system of a 2000 fps high-speed camera at the end of the diversion pipe, and uses image recognition technology and high-precision counting software to achieve dynamic counting, with an error rate < 0.5%, and records the number of fry in real time and accurately; Next, the fingerlings after counting directly flow into the fry transportation box through the conveying pipeline. The specifications of the fry transportation box are 1.25 m in length, 0.8 m in width, and 1 m in height. Its outer layer (support layer) is made of carbon fiber reinforced resin (CFRP), the middle layer is a bio-based closed-cell foam material, and the inner layer (water bag) is a multi-layer composite high-strength flexible material. It is equipped with an independent circulating water system and a liquid oxygen supply system, and integrates the interface of the central liquid oxygen supply system; the conveying pipeline is equipped with a buffer and diversion system. In the mixing chamber, the fingerlings and water form a suspension according to a volume ratio of 4:1, and 0.2 kg / m³ of buffer agent (the buffer agent uses polyvinyl alcohol 17-92, abbreviated as PVA 17-92) is added to reduce the friction between fish bodies and between the fish body and the pipe wall. Subsequently, a low-pressure air flow generated by a low-pressure blower or an air compressor is injected from the bottom of the conveying pipeline at a speed of 8 m / s, generating a Venturi effect, driving the fish-water mixture to form a segmented plug flow (non-continuous full pipe flow), so that the fingerlings are always wrapped by the water medium to avoid direct friction with the pipe wall; the fish-water mixture advances in a pulsed manner at 3 pulses per second. At this time, the fingerlings move in a spiral forward trajectory in the pipeline, with an average conveying speed of 1 m / s. When the fish-water mixture enters the fish-water separation device, the fish and water are automatically separated through an inclined screen. The separated water can be recycled after filtration. The fingerlings remain in a low-stress state during transportation, without being affected by severe bumps or sudden temperature changes; the fry transportation box is equipped with an automatic identification tag and positioning system, enabling the fry transportation box to be accurately identified and positioned; Subsequently, the fry transportation box is transported to the loading area of the special fry transport vehicle by the rail transportation system. The rail system is driven by an automatic navigation and precise positioning module, enabling the fry transportation box to move stably and accurately during transportation; in the loading area of the transport vehicle, a crane device equipped with a variable-speed intelligent control system is used to automatically lift the fry transportation box from the rail to the transport vehicle. The operation of the crane is slow and stable throughout the process to prevent fry stress caused by sudden stops or rapid vibrations. After loading, the transport vehicle drives to the dock, and the fry transportation box is directly lifted onto the deck of the transport ship using the dock crane; after the transport ship sails to the modern ocean ranch, the fingerlings in the fry transportation box are inverted and introduced into the net cage with a knotless screen structure with a mesh size of 5 meshes pre-arranged using the crane on the ship. Example 2

[0012] In the nursery pond of the same industrialized seedling-raising workshop as in Example 1, the water level of the nursery pond was lowered to 58 cm, and the 6-inch plastic pipe inserted at the bottom of the nursery pond was opened. The fry were smoothly discharged through the preset sewage pipeline and transported to the fry collection pond. The subsequent steps were the same as those in Example 1, except that in the buffer and diversion system of the transport pipeline, the fry and water formed a suspension in a volume ratio of 3:1, and a buffer agent of 0.1 kg / m³ was added (the buffer agent was polyvinyl alcohol 17-92, abbreviated as PVA 17-92). The low-pressure air flow velocity was 6 m / s, the pulse frequency of the fish-water mixture was 2 pulses per second, and the average transport velocity was 0.8 m / s. The fry were finally introduced into the net cage. Example 3

[0013] In the nursery pond of the same industrialized seedling-raising workshop as in Example 1, the water level of the nursery pond was lowered to 62 cm for discharging the fry and transporting them to the fry collection pond. After the intelligent counting of the fry and their transfer in water, when entering the step of transporting the fry to the fry transport box, in the buffer and diversion system of the transport pipeline, the fry and water formed a suspension in a volume ratio of 5:1, and a buffer agent of 0.3 kg / m³ was added (the buffer agent was polyvinyl alcohol 17-92, abbreviated as PVA 17-92). The low-pressure air flow velocity was 12 m / s, the pulse frequency of the fish-water mixture was 4 pulses per second, and the average transport velocity was 1.2 m / s. The operations in other links were the same as those in Example 1, and the fry were finally introduced into the net cage.

[0014] Test Example The purpose of this test group was to explore the influence of different transfer conditions on the transfer of fry, and to detect the high efficiency, stability and improvement effect of the survival rate of the fry transfer of the present invention.

[0015] Test objectives: Test Group A, Test Group B and Test Group C respectively adopted the fry transfer conditions provided in Examples 1-3; the control examples adopted Control Group A, Control Group B, Control Group C and Control Group D, where: Control Group A In the nursery pond of an industrialized seedling-raising workshop with a length of 47 m and a width of 17 m, there were 20 nursery ponds with a length of 6 m, a width of 3.5 m and a depth of 1.5 m. A passage with a width of 2 m and a length of 47 m was set in the middle of the 20 nursery ponds; the water level of the nursery pond was lowered to 60 cm, and the 6-inch plastic pipe inserted at the bottom of the nursery pond was opened. The fry were discharged and transported to the fry collection pond through the preset sewage pipeline, but the sewage pipeline was not provided with a buffer section and a flow velocity control device, and the water flow impact was large, and the fry were greatly stressed during the transfer process; afterwards, a water basin device was used to collect the fry in the fry collection net cage. The collected fry were introduced into an ordinary counting machine for counting, and the counted fry flowed into the fry transport box through an ordinary transport pipeline. The fry transport box did not have an independent circulating water system and a liquid oxygen supply system, and only simple oxygenation measures were adopted; afterwards, the fry transport box was transported by a crane to the loading area of the fry special transport vehicle. After the transport ship sailed to the modern ocean ranch, the fry were introduced into the net cage.

[0016] Control group B In the nursery pond of the industrialized seedling-raising workshop, the transfer of fry from the nursery pond to the fry collection pond is carried out normally, and the intelligent counting of fry and the operation in the water transfer link are normal. In the step of transporting the fry to the transport box, the internal of the fry collection box adopted does not have a buffer diversion channel and a multi-section partition design, and it is impossible to effectively disperse and relieve the uneven stress generated by the water flow impact and mechanical vibration during the transfer process. Although there is a basic conveying structure in the conveying pipeline, the flow rate cannot be accurately regulated, and the risk of vibration and collision of the fry during the conveying process is relatively high. The subsequent links such as handling and transporting the transport box are the same as those in Example 1.

[0017] Control group C The traditional plastic bag oxygenation transportation method is adopted. The four-finger threadfin bream fry are directly loaded into the plastic bag, and after filling with an appropriate amount of oxygen, they are transported; during the transportation process, the fry are easily damaged mechanically, the dissolved oxygen content is difficult to maintain continuously, the water temperature is also difficult to control during the transportation process, and the fry secrete a large amount of mucus due to stress reaction, resulting in an increase in the mortality rate; at the same time, manual counting is adopted in the counting link, with low efficiency and large errors; finally, the fry are put into the net cage.

[0018] Control group D In the transfer process from the nursery pond to the fry collection pond, a simple buffer device is set, but the effect is limited. In the intelligent counting link of the fry, a counting device with relatively low precision is adopted, and the counting error is relatively large; when the fry are transported to the transport box, the buffer diversion system of the conveying pipeline is not perfect enough to control the flow rate and protect the fry well; the transport box is equipped with a simple oxygenation device, but it cannot supply oxygen stably and control the water quality; during the transportation process, ordinary vehicles are used for transportation, and it is impossible to effectively regulate environmental factors such as temperature; finally, the fry are put into the net cage.

[0019] Test conditions: 1. Fry selection: Select four-finger threadfin bream fry with similar specifications (body length about 5-8 cm) and healthy without diseases, and 1000 fry are used in each group of tests; 2. Environmental conditions: The tests are carried out under the same environmental conditions such as weather, water temperature (25°C - 28°C), salinity (28‰ - 32‰), etc., and the transfer distance is the same (the distance from the seedling-raising workshop to the marine ranch is fixed).

[0020] 3. Equipment conditions: Except for the different transfer equipment and measures adopted by each test group and control group, other auxiliary equipment (such as cranes, dock facilities, etc.) remains the same.

[0021] The calculation formula is as follows: Fry survival rate: Survival rate = (Number of finally surviving fry / Number of initial fry) × 100%; Seedling damage rate: Damage rate = (Number of damaged seedlings / Initial number of seedlings) × 100% (Damage includes mechanical damage, physical abnormalities caused by stress, etc.); Transport efficiency: Transport efficiency = Total number of transported seedlings / Total transport time (Unit: tails / hour); Experimental method: Data collection: At each link of seedling transportation, including from the nursery pond to the seedling collection pond, intelligent counting of seedlings and water transportation, transporting seedlings to the seedling transport box, land rail transportation to the transport vehicle, crane transfer to the transport vehicle and then to the dock and sea transportation, and finally releasing the seedlings from the transport ship to the net cage, etc., record data such as the number of seedlings, status (whether there is damage, degree of stress reaction, etc.), and transport time; Water quality monitoring: During the transportation process, monitor and record the water quality (including dissolved oxygen, pH value, water temperature, etc.) in the seedling transport box every 1 hour; Stress reaction assessment: Evaluate the degree of stress reaction of the seedlings by observing the behavioral manifestations of the seedlings (such as swimming state, whether there is aggregation or dispersion, whether there is abnormal swimming, etc.) and physiological indicators (such as mucus secretion volume, body color change, etc.), which are divided into three levels: mild stress, moderate stress, and severe stress; Repeated experiments: To ensure the reliability of the experimental results, each experimental group and control group are repeated 3 times, and the average value is taken as the final result.

[0022] Specific detection indicators are shown in Table 1.

[0023] Table 1 Detection indicators of each sample Test Example A Test Example B Test Example C Control Group A Control Group B Control Group C Control Group D Initial number of fry (tails) 1000 1000 1000 1000 1000 1000 1000 Final number of surviving fry (tails) 992 988 990 920 940 880 900 Survival rate (%) 99.2 98.8 99.0 92.0 94.0 88.0 90.0 Number of damaged fry (tails) 8 12 10 80 60 120 100 Damage rate (%) 0.8 1.2 1.0 8.0 6.0 12.0 10.0 Total transportation time (h) 5 5.2 4.8 6 5.5 7 6.5 Transportation efficiency (tails / h) 200. 192.3 208.3 166.7 181.8 142.9 153.8 Average dissolved oxygen (mg / L) 6.5 6.3 6.6 5.0 5.5 4.5 5.2 Average water temperature (°C) 26.5 26.2 26.8 26 26.3 25.5 26 Degree of stress response (proportion) Mild stress: 90%, Moderate stress: 10%, Severe stress: 0% Mild stress: 88%, Moderate stress: 12%, Severe stress: 0% Mild stress: 92%, Moderate stress: 8%, Severe stress: 0% Mild stress: 60%, Moderate stress: 30%, Severe stress: 10% Mild stress: 70%, Moderate stress: 25%, Severe stress: 5% Mild stress: 40%, Moderate stress: 40%, Severe stress: 20% Mild stress: 50%, Moderate stress: 35%, Severe stress: 15% According to Table 1, the summary of the above comparison data is as follows: In terms of survival rate: The survival rates of the fry in experimental groups A, B, and C were 99.2%, 98.8%, and 99.0% respectively, all at a relatively high level. This is attributed to the buffer discharge pipeline and the water transportation system adopted in the transportation method of the present invention, which keep the fry in a stable water environment throughout the process from the nursery pond to the fry collection box, reducing the mechanical shock and the stimulation caused by environmental changes. The independent circulating water system and liquid oxygen supply system equipped in the fry transportation box can control environmental factors such as water quality, temperature, and dissolved oxygen, avoiding stress caused by sudden environmental changes, thus effectively improving the survival rate of the fry. In control group A, since the sewage pipeline was not equipped with a buffer section and a flow rate regulating device, the water flow impact was large, and only simple oxygenation was carried out in the fry transportation box, with a survival rate of 92.0%. In control group B, no buffer diversion channel and multi-section partition design were set inside the fry collection box, and the flow rate of the transportation pipeline could not be accurately regulated, with a survival rate of 94.0%. In control group C, traditional plastic bags were used for oxygenation transportation, and the fry were easily mechanically damaged, and the dissolved oxygen and water temperature were difficult to control, with a survival rate of only 88.0%. In control group D, the equipment and measures in each link were not perfect, with a survival rate of 90.0%. The lower survival rates of these control groups highlight the advantages of the transportation method of the present invention in maintaining the stability of the fry living environment.

[0024] In terms of injury rate: The injury rates of the fry in experimental groups A, B, and C were 0.8%, 1.2%, and 1.0% respectively, at a relatively low level. In the transportation method of the present invention, the buffer diversion system in the transportation pipeline reduces the friction between fish bodies and between the fish body and the pipe wall, and reduces the injury risk of the fry by controlling the flow rate change, adding buffer agents, and forming segmented plug flow. The buffer diversion channel and multi-section partition design inside the fry collection box can also effectively disperse and relieve the uneven stress generated by the water flow impact and mechanical vibration during the transportation process, thereby reducing the injury rate. The injury rates of control groups A, B, C, and D were 8.0%, 6.0%, 12.0%, and 10.0% respectively, significantly higher than those of the experimental groups, indicating that the transportation method of the present invention has a good effect in reducing the mechanical injury of the fry.

[0025] In terms of transportation efficiency: The transportation efficiencies of experimental groups A, B, and C were 200 tails / h, 192.3 tails / h, and 208.3 tails / h respectively, which were relatively high. In the transportation method of the present invention, the intelligent counting machine realizes dynamic counting, with an error rate <0.5%, and records the number of fry in real time and accurately, improving the counting efficiency. The fully automated track, crane, and intelligent monitoring system realize the efficient coordinated operation of each link, shortening the total transportation time, and thus improving the transportation efficiency. The transportation efficiencies of control groups A, B, C, and D were 166.7 tails / h, 181.8 tails / h, 142.9 tails / h, and 153.8 tails / h respectively, which were lower than those of the experimental groups.

[0026] In terms of dissolved oxygen: The average dissolved oxygen levels of experimental groups A, B, and C were 6.5 mg / L, 6.3 mg / L, and 6.6 mg / L respectively, maintaining at a relatively high level. The independent circulating water system and liquid oxygen supply system equipped in the fry transportation box, as well as the integrated central liquid oxygen supply system interface, can continuously provide sufficient oxygen for the fry, ensuring the survival needs of the fry during transportation; The average dissolved oxygen levels of control groups A, B, C, and D were 5.0 mg / L, 5.5 mg / L, 4.5 mg / L, and 5.2 mg / L respectively, lower than those of the experimental groups, indicating that the transportation method of the present invention has more advantages in dissolved oxygen control and can provide a more suitable living environment for the fry.

[0027] In terms of water temperature: The average water temperatures of experimental groups A, B, and C were 26.5 °C, 26.2 °C, and 26.8 °C respectively, which were relatively stable and suitable for the survival of fry. The intelligent temperature control system equipped in the special fry transport vehicle can adjust the temperature inside the vehicle, meeting the temperature requirements of the fry and reducing the stress response caused by temperature changes; The average water temperatures of control groups A, B, C, and D were 26 °C, 26.3 °C, 25.5 °C, and 26 °C respectively. Although there were certain fluctuations, the amplitude was relatively small. However, the water temperature of control group C fluctuated greatly, affecting the living environment of the fry; It shows that the transportation method of the present invention is more stable in water temperature control.

[0028] In terms of the degree of stress response: The stress responses of experimental groups A, B, and C were mainly mild stress, with proportions of 90%, 88%, and 92% respectively. The proportion of moderate stress was relatively low, and there was no severe stress; The transportation method of the present invention reduces the stress response caused by environmental mutations and mechanical damage by setting buffer diversion systems and configuring intelligent devices in each link, enabling the fry to always be in a stable water environment and a suitable living environment; Among the stress responses of control groups A, B, C, and D, the proportions of moderate stress and severe stress were relatively high. The proportion of severe stress in control group C reached 20%, indicating that the transportation method of the present invention has obvious effects in reducing the stress response of fry and can effectively improve the survival quality and survival rate of fry.

[0029] In summary, by setting up a buffer and diversion system and configuring intelligent devices at each link of transportation, such as buffer discharge pipelines and underwater transportation systems, intelligent counting machines, seedling transportation boxes equipped with independent circulating water and liquid oxygen supply systems, automated rails and cranes, and intelligent monitoring systems, etc., seamless connection of each link from the nursery pond to the ocean ranch and continuous and stable control of the water environment have been achieved. This not only effectively reduces the stress response of fry, reduces mechanical damage, and avoids stress caused by sudden environmental changes, but also controls environmental factors such as water quality, temperature, and dissolved oxygen. At the same time, the intelligent counting machine realizes efficient and accurate counting, and the efficient and coordinated operation of each link improves the transportation efficiency, fundamentally solving the problem of high mortality rate of fry caused by mechanical damage, sudden environmental changes, and stress response during transportation, improving the survival rate and survival quality of fry, and enhancing the transportation efficiency.

[0030] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A method for high-efficiency and low-stress transportation of four-fingered threadfin fry by land and sea relay, characterized in that: The following steps are involved: S1. Transfer from nursery pond to seedling collection pond: There are 20 nursery ponds in the factory nursery workshop, with a passage in the middle. First, adjust the water level of the nursery pond, open the plastic pipe at the bottom of the pond, and discharge the fry steadily through the preset sewage pipe and transport it to the seedling collection pond; S2. Intelligent fry counting and underwater transfer: The fry in the fry collection cage is collected using a water basin device. The collected fry are smoothly and evenly introduced into the intelligent counting machine for automatic counting operation, and the number of fry is recorded in real time and accurately; S3, the fry are transported to the fry transport box: the fry after counting are directly flowed into the fry transport box through the transport pipeline. The buffer diversion system in the pipeline is composed of a smooth pipeline, a low-pressure air source system, a mixing chamber, a fish-water separation device and a control unit. In the mixing chamber, the fry and water form a suspension, and a buffer is added. The low-pressure airflow drives the flow in a segmented plug shape, and the fish and water are separated after pulse propulsion; S4. Transport from land rail to transport vehicle: The seedling transport box is equipped with an automatic identification label and positioning system, and the seedling transport box is transported by the rail transport system to the loading area of ​​the special transport vehicle for fry; S5. Transfer by crane to transport vehicle and then to the dock and sea transport: Use crane equipment equipped with variable speed intelligent control system to lift the seedling box onto the transport vehicle. The loaded transport vehicle drives to the dock and then is lifted to the deck of the transport ship by the dock crane; S6. Final placement from the transport ship to the cages: After the transport ship sails to the modern marine ranch, the fry in the fry transport boxes are inverted and introduced into the cages using the ship's crane.

2. The method for high-efficiency and low-stress land-sea relay transportation of four-fingered threadfin fry according to claim 1, characterized in that: In the S1, the specifications of the factory-scale seedling nursery are 47m long and 17m wide; the specifications of the 20 seedling nursery pools are 6m long, 3.5m wide and 1.5m deep; the specifications of the passages are 2m wide and 47m long, and the passages are grouped into 2 pools on the left and 2 pools on the right to form a seedling collection pool.

3. The method for high-efficiency and low-stress land-sea relay transportation of four-fingered threadfin fry according to claim 1, characterized in that: In S1, the water level in the nursery pond drops to 55cm-65cm, and the specification of the plastic pipe is 6 inches.

4. The method for high-efficiency and low-stress land-sea relay transportation of four-fingered threadfin fry according to claim 1, characterized in that: In S2, the water basin device is a closed structure, and the bottom is inclined.

5. The method for high-efficiency and low-stress land-sea relay transportation of four-fingered threadfin fry according to claim 1, characterized in that: In S2, the intelligent counting machine integrates a machine vision system with a 2000fps high-speed camera at the end of the guide tube, and uses image recognition technology and high-precision counting software to achieve dynamic counting with an error rate of less than 0.5%.

6. The method for high-efficiency and low-stress land-sea relay transportation of four-fingered threadfin fry according to claim 1, characterized in that: In the S3, an overflow port is provided at 15 cm on the top of the seedling transport box for fish-water separation and controlling the water level of the seedling transport box; the specifications of the seedling transport box are 1.25 m in length, 0.8 m in width and 1 m in height, and its outer layer is made of carbon fiber reinforced resin, the middle layer is a bio-based closed-cell foam material, and the inner layer is a multi-layer composite high-strength flexible material, and it is equipped with an independent circulating water system and liquid oxygen supply system, and an integrated central liquid oxygen supply system interface.

7. The method for high-efficiency and low-stress land-sea relay transportation of four-fingered threadfin fry according to claim 1, characterized in that: In S3, the fry and water form a suspension according to a volume ratio of 3:1-5:1, and the amount of the buffer added is 0.1kg / m³-0.3kg / m³.

8. The method for high-efficiency and low-stress land-sea relay transportation of four-fingered threadfin fry according to claim 1, characterized in that: In S3, the pulse propulsion is carried out at 2-4 pulses per second. At this time, the fry advances in a spiral trajectory in the pipeline, and the average conveying speed is 0.8m / s-1.2m / s.

9. The method for high-efficiency and low-stress land-sea relay transportation of four-fingered threadfin fry according to claim 1, characterized in that: In the S4, there are two specifications of the special transport vehicle for fry, namely, a 7m long 8-box vehicle and a 14m long 16-box vehicle. The special transport vehicle for fry has an automatic opening and closing function of the top cover, and is equipped with temperature control, liquid oxygen supply and video observation system.

10. The method for high-efficiency and low-stress land-sea relay transportation of four-fingered threadfin fry according to claim 1, characterized in that: In S6, the net box adopts a knotless screen structure with a mesh size of 5 meshes, and the net box has a water circulation function.

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