A welfare screening method for heat-resistant flounder

Abstract

This invention discloses a welfare screening method for flounder with temperature tolerance traits, comprising: screening juvenile / adult fish from different families or aquaculture groups by utilizing the flounder's avoidance behavior towards unsuitable temperatures; by raising (lowering) the water temperature, as the bottom water temperature rises (falls), the flounder exhibits avoidance behavior towards unsuitable temperatures, manifested as faster / slower breathing and swimming away from the bottom of the container; the container can be set with a heating (lowering) rate, accurately displaying and recording the heating (lowering) time, bottom and bottom layer (1 cm) temperatures; a camera synchronously records the number of respirations (respiratory frequency) of the flounder per unit time in conjunction with the heating (lowering) time; and determining the suitable temperature limit or tolerance temperature limit of the flounder through coupling analysis. This invention implements non-invasive welfare screening based on the differences in physiological and behavioral phenotypes of flounder in response to temperature changes, selecting individuals tolerant to high (low) temperatures from aquaculture groups, improving the breeding rate of superior stock, and reducing the cost of selecting superior broodstock.

Description

Technical Field

[0001] This invention relates to a method for screening stress resistance traits in marine bony fish, and more particularly to a welfare screening method for flounder with heat tolerance traits. Background Technology

[0002] In recent years, my country's aquaculture industry has developed rapidly, with its aquaculture output currently accounting for over 70% of global aquaculture production. However, due to outdated aquaculture management and breeding theories, environmental changes and human stress are unavoidable, especially the significant impact of high summer temperatures on the survival of cold-water fish. Therefore, selecting healthy and heat- (low-temperature) tolerant fish species can effectively reduce or avoid large-scale mortality during aquaculture and improve production efficiency. Furthermore, highly resilient populations can increase the breeding rate of superior species and reduce aquaculture costs. Therefore, screening for heat- (low-temperature) tolerant fish species is of great significance for improving aquaculture management and breeding techniques in my country and promoting the technological upgrading of the turbot farming industry. Summary of the Invention

[0003] To address the aforementioned problems, the purpose of this invention is to provide a welfare screening method for flounder with heat tolerance traits, enabling scientific and effective welfare screening and evaluation of flounder with heat (low temperature) tolerance traits.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides a welfare screening method for turbot with high-temperature (low-temperature) tolerance traits, comprising the following steps:

[0006] S1: Place flounder of different family lines or farming groups that are over 55 days old into the farming system for temporary rearing, ensuring the same feeding conditions and that the flounder are not subjected to external stress. Stop feeding the day before selection.

[0007] S2: Set the initial temperature and heating (cooling) rate to heat (cool) the water, accurately display and record the heating (cooling) time, bottom and bottom layer (1 cm) temperature, and at the same time the camera accurately captures the behavior trajectory and gill cover movement of the flounder in the water.

[0008] S3: Place flounder over 55 days old into a transparent container with controllable temperature rise and fall, and set the initial temperature, target temperature, and time required to reach the target temperature;

[0009] S4. Record the turbot in the container using a camera to determine the number of times the turbot breathes per unit time, i.e., the respiratory rate;

[0010] S5: Record the temperatures corresponding to the first and second times the flounder left the bottom after the obvious changes in its respiration, and perform coupling analysis on the respiration rate to determine the suitable temperature limit and the tolerance temperature limit of the flounder.

[0011] S6: Based on the flounder obtained in steps S1 to S5, select flounder with high tolerance to high temperature (low temperature) as broodstock for breeding.

[0012] Preferably, in step S1, the rearing conditions are as follows: the water temperature in the rearing system is 17-19℃ when there is no stress, the light and dark time are 12 hours each, the pH value is 7.5-8.5, the dissolved oxygen concentration is ≥6.8mg / L, the ammonia nitrogen concentration is ≤0.1mg / L, the nitrite nitrogen concentration is ≤0.1mg / L, and the sulfide concentration is ≤0.1mg / L; the absence of external stress means that feeding is stopped 24 hours before the start, and the flounder to be screened is placed on the platform 2 hours before the start, while avoiding personnel movement in the surrounding environment, and waiting for the screening to begin.

[0013] Preferably, in step S2, the initial temperature is the optimal culture temperature for flounder; the heating (cooling) rate is the temperature change per unit time; the bottom temperature is the temperature at the bottom of the inner wall of the container, i.e., the temperature sensed by the flounder; and the bottom layer temperature is the temperature of the water layer where the flounder is located.

[0014] Preferably, in step S3, 55-day-old or older flounder are placed in a cubic transparent container with controllable temperature rise and fall 2 hours in advance. In order to eliminate human stress, the temperature is set to be heated (cooled) in a gradient of 3-5°C every half hour, so that the bottom water temperature is heated (cooled) from the optimal breeding temperature of flounder to below (above) the lethal temperature of flounder. More preferably, the bottom water temperature is raised or lowered by 5°C every 35 minutes.

[0015] Preferably, in step S4, the camera marks the flounder to be screened and records the entire process, enabling visualization of its behavior when moving between water layers, when it swims away from the bottom of the container under stress, and the visualization of gill cover undulations.

[0016] Preferably, in step S5, the respiratory rate is based on the visualization of gill cover undulations, recording the number of times the flatfish breathes per unit time; the method for determining the suitable temperature limit and the tolerance temperature limit of the flatfish is as follows: as the temperature rises, the flatfish's breathing accelerates significantly, the number of gill movements increases, and the respiratory rate gradually increases. At this time, the flatfish leaves the bottom for the first time, and the temperature corresponding to the time of leaving the bottom is the suitable temperature limit of the flatfish. From this point, the welfare screening of flatfish with high temperature (low temperature) tolerance traits ends; after the respiratory rate reaches its peak and then decreases, the flatfish leaves the bottom for the second time, and the temperature corresponding to the time of leaving the bottom is the tolerance temperature limit of the flatfish.

[0017] In step S6, the high-temperature tolerance flounder is a high-temperature tolerant family or farmed population whose suitable temperature and tolerance temperature are both higher than those of general families or farmed populations, as determined by coupling analysis.

[0018] The flounder with high low-temperature tolerance is a low-temperature tolerant family or aquaculture group whose suitable temperature and tolerance temperature are both lower than those of general families or aquaculture groups, as determined by coupling analysis.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. This invention utilizes the avoidance behavior of flounder in response to unsuitable temperatures to screen juvenile / adult fish from different families or farmed populations. The operation is simple. By measuring the suitable temperature limit of flounder, families or farmed populations with high tolerance to high (low) temperatures can be screened out. Flounder with high tolerance to high (low) temperatures can be accurately screened out in a short time.

[0021] 2. Traditional screening methods use extreme lethal temperatures, which can easily cause large-scale deaths and severe stress. From an animal welfare perspective, this invention uses a non-invasive screening method that causes less stress and less damage to fish, thus reducing the cost of screening superior broodstock.

[0022] 3. This invention can effectively improve the breeding rate of flounder with high tolerance to high (low) temperatures by accurately selecting them, and can be widely used in large-scale aquaculture.

[0023] In summary, this invention is a welfare screening method for flounder with high temperature (low temperature) tolerance. It utilizes temperature tolerance welfare screening combined with the physiological characteristics of flounder in response to extreme temperature stress and their avoidance behavior in response to unsuitable temperatures to screen flounder with high temperature (low temperature) tolerance from general families or aquaculture populations as broodstock for aquaculture. This non-invasive welfare screening effectively avoids the large-scale mortality and severe stress caused by commonly used high (low) temperature survival screening methods, improves the breeding rate of superior breeds, and reduces the cost of screening superior broodstock. Attached Figure Description

[0024] Figure 1 This is a diagram showing the difference in suitable temperature between family 1 and family 2 in the example.

[0025] Figure 2 This is a graph showing the difference in temperature tolerance between family 1 and family 2 in the examples. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention utilizes the non-specificity of stress, based on the principle that the temperature stress response behavior of flatfish with different temperature tolerances varies with temperature stimulation, to screen flatfish aged 55 days and older. Fish with low temperature tolerance will escape high (low) temperature areas at a lower suitable temperature limit, and their respiratory rate will gradually increase and then decrease; fish with high temperature tolerance will reach their suitable temperature limit after being subjected to high (low) temperature stress and escape from high (low) temperature areas, escaping at even higher (lower) tolerance temperatures. However, the screening process must use scientific and reasonable testing methods to avoid excessive stress and death caused by unreasonable temperature settings, while accurately selecting flatfish tolerant to high (low) temperatures, based on reasonable welfare screening methods.

[0028] The present invention will now be described in detail with reference to implementation examples.

[0029] Example 1

[0030] This embodiment provides a welfare screening method for turbot with high-temperature (low-temperature) tolerance traits, the steps of which are as follows:

[0031] S1. Select 55-day-old juvenile turbot from two families, family 1 and family 2, for aquaculture, and ensure the same rearing conditions. The rearing conditions are as follows: water temperature in the aquaculture system is 18℃ when there is no stress, light and dark time are 12 hours each (light time is 9:00-21:00, dark time is 21:00-9:00 the next day), pH value is 7.5-8.5, dissolved oxygen concentration is ≥6.8mg / L, ammonia nitrogen concentration is ≤0.1mg / L, nitrite nitrogen concentration is ≤0.1mg / L, and sulfide concentration is ≤0.1mg / L.

[0032] S2. Stop feeding 24 hours before the start. 2 hours before the start, put the juvenile turbot to be screened into a 300mL cubic glass transparent container with controllable temperature rise and fall. At the same time, avoid people walking around the environment and wait for the screening to begin.

[0033] S3. Use a controllable temperature-regulating container to screen juvenile turbot from families 1 and 2. The initial temperature is set to the optimal culture temperature of juvenile turbot at 18℃. The water is then heated in a gradient manner at 20℃, 25℃, 30℃, and 35℃ to raise the bottom water temperature from 18℃ to 32℃. The heating time is set at 5℃ every 35 minutes, with a total heating time of 98 minutes.

[0034] S4. Using a camera equipped with a temperature tolerance welfare screening system, the juvenile turbot in a transparent container with controllable temperature rise and fall is recorded and analyzed to determine the number of times the juvenile turbot breathes per unit time, i.e., the respiratory rate; at the same time, the behavior of the juvenile turbot when it moves between water layers, when it swims away from the bottom of the container under stress, and the gill cover undulation are visualized.

[0035] S5. Record the temperatures corresponding to the first and second times the juvenile turbot leaves leave the bottom after their breathing has increased significantly. Perform a coupling analysis on the number of breaths per unit time when the leaves leave the bottom, i.e., the respiratory frequency, to determine the suitable temperature limit and the tolerance temperature limit of the juvenile turbot to be screened.

[0036] The respiratory rate was determined by visualizing gill cover undulations, accurately recording the number of breaths per unit time for juvenile turbot. A coupling analysis of the respiratory rate per unit time at the point of escaping the bottom was performed to determine the suitable and tolerable temperature limits for the selected juvenile turbot. The method was as follows: as the temperature increased, the respiration rate of the juvenile turbot significantly accelerated, the number of gill movements increased, and the respiratory rate gradually increased. At this point, the juvenile turbot experienced its first escaping from the bottom, and the temperature corresponding to this escaping was the suitable temperature limit for that juvenile turbot. After the respiratory rate reached its peak, it decreased, and the juvenile turbot experienced its second escaping from the bottom; the temperature corresponding to this escaping was the tolerable temperature limit for that juvenile turbot.

[0037] S6. Based on the juvenile turbot obtained in steps S1 to S5, select juvenile turbot with high tolerance to high temperatures as broodstock for aquaculture.

[0038] Test Results

[0039] Using Example 1 as the test sample, the effects of other examples are similar to those of the examples described above.

[0040] Six juvenile turbot were selected from each of family 1 and family 2, which were screened using the method of this invention, for testing:

[0041] (1) Test of suitable temperature limits for juvenile turbot from family 1 and family 2

[0042] Test results are available Figure 1 As shown, after heating for 42 minutes, the bottom water temperature rose to 24℃, and the respiratory rate of the juvenile turbot increased. In family 1, the respiratory rate of each juvenile turbot was 60, 55, 58, 64, 58, and 45 times per unit time, with an average respiratory rate of 57 breaths / min. After this, the first time the fish left the bottom occurred, and the corresponding bottom water temperature was its suitable temperature limit of 24.9–27.3℃. In family 2, the respiratory rate of each juvenile turbot was 60, 70, 65, 68, 75, and 78 times per unit time, with an average respiratory rate of 69 breaths / min. After this, the first time the fish left the bottom occurred, and the corresponding bottom water temperature was its suitable temperature limit of 27.2–28.4℃.

[0043] (2) Temperature tolerance limit test of juvenile turbot from family 1 and family 2

[0044] Test results are available Figure 2As shown, after heating for 70 minutes, the bottom water temperature rose to 28℃. The respiratory rates of each juvenile turbot in family 1 were 78, 79, 82, 87, 88, and 75 breaths per unit time, respectively. After heating for 84 minutes, the bottom water temperature rose to 30℃. The respiratory rates of each juvenile turbot in family 1 were 17, 11, 15, 14, 22, and 24 breaths per unit time, respectively, with an average respiratory rate of 17 breaths / min. The respiratory rate increased sharply and then decreased, indicating a second bottom escape. The bottom escape temperature at this point was its tolerance temperature limit of 26.8–28.5℃, and its lethal temperature was 28.3–29℃. After heating for 70 minutes, the bottom water temperature rose to 28℃. The respiratory rate of each juvenile turbot in family 2 was 83, 91, 88, 95, 80, and 93 times per unit time, respectively. After heating for 84 minutes, the bottom water temperature rose to 30℃. The respiratory rate of each juvenile turbot in family 2 was 58, 65, 70, 48, 44, and 50 times per unit time, respectively. The average respiratory rate was 56 breaths / min. The respiratory rate increased sharply and then decreased, and the fish escaped the bottom for the second time. The temperature at which the fish escaped the bottom was its tolerance temperature limit of 29.6-31.8℃, and its lethal temperature was 32.7-34.1℃.

[0045] The test results show that the first and second temperatures of juvenile turbot from family 2 were higher than those from family 1, indicating that family 2 has a higher tolerance to high temperatures than family 1. Therefore, family 1 is considered a general family, while family 2 is a family with high temperature tolerance. Although the difference in tolerance temperature limits is greater than the difference in suitable temperature limits, determining the suitable temperature limits for turbot can screen out families or aquaculture groups with high tolerance to high (low) temperatures, resulting in better welfare.

[0046] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A welfare screening method for flounder with heat tolerance traits, characterized in that, The temperature resistance property includes high temperature resistance and low temperature resistance, and includes the following steps: S1: Place flounder of different family lines or breeding groups that are over 55 days old into the breeding system for temporary rearing, ensuring the same feeding conditions and that the flounder are not subjected to external stress. Stop feeding the day before selection. S2: For high-temperature resistance, set the initial temperature and heating rate to heat the water, accurately display and record the heating time, the temperature at the bottom and 1 cm below the bottom layer, and at the same time, the camera accurately captures the behavior trajectory of the flounder in the water and the movement of its gill covers. For low-temperature resistance, the initial temperature and cooling rate are set to cool the water. The cooling time and the temperature at the bottom and 1 cm below the bottom are accurately displayed and recorded. At the same time, the camera accurately captures the behavior trajectory of the flounder in the water and the movement of its gill covers. S3: Place flounder over 55 days old into a transparent container with controllable temperature rise and fall, and set the initial temperature, target temperature, and time required to reach the target temperature; S4. Record the turbot in the container using a camera to determine the number of times the turbot breathes per unit time, i.e., the respiratory rate; S5: Record the temperatures corresponding to the first and second times the flounder left the bottom after significant changes in its respiration, and perform coupling analysis on the respiration rate to determine the suitable temperature limit and tolerance temperature limit of the flounder. S6: Based on the flounder obtained in steps S1 to S5, select flounder with high tolerance to high temperature or low temperature as broodstock for breeding. In step S4, the camera marks the flounder to be screened and records the entire process, enabling visualization of its behavior when moving between water layers, when it swims away from the bottom of the container under stress, and the visualization of gill cover undulations. In step S5, the respiratory rate is based on the visualization of gill cover undulation, recording the number of times the flounder breathes per unit time. The method for determining the suitable temperature limit and tolerance temperature limit of the turbot is as follows: as the temperature rises, the turbot's respiration speeds up, the number of gill movements increases, and the respiratory rate gradually increases. At this time, the turbot leaves the bottom for the first time. The temperature corresponding to the time of leaving the bottom is the suitable temperature limit of the turbot, and the welfare screening of turbot with temperature tolerance traits is completed. After the respiratory rate reaches its peak and then decreases, the turbot leaves the bottom for the second time. The temperature corresponding to the time of leaving the bottom is the tolerance temperature limit of the turbot. In step S6, the high-temperature tolerance flounder is a high-temperature tolerant family or farmed population whose suitable temperature and tolerance temperature are both higher than those of general families or farmed populations, as determined by coupling analysis. The flounder with high low-temperature tolerance is a low-temperature tolerant family or aquaculture group whose suitable temperature and tolerance temperature are both lower than those of general families or aquaculture groups, as determined by coupling analysis.

2. The welfare screening method for heat-resistant flounder according to claim 1, characterized in that, In step S1, the rearing conditions are as follows: the water temperature in the rearing system is 17~19℃ when there is no stress, the light and dark time are 12 hours each, the pH value is 7.5~8.5, the dissolved oxygen concentration is ≥6.8 mg / L, the ammonia nitrogen concentration is ≤0.1 mg / L, the nitrite nitrogen concentration is ≤0.1 mg / L, and the sulfide concentration is ≤0.1 mg / L; the absence of external stress means that feeding is stopped 24 hours before the start, and the flounder to be screened is placed on the platform 2 hours before the start, while avoiding personnel movement in the surrounding environment, and waiting for the screening to begin.

3. The welfare screening method for heat-resistant flounder according to claim 1, characterized in that, In step S2, the initial temperature is the optimal culture temperature for flounder; the heating or cooling rate is the temperature change per unit time; the bottom temperature is the temperature at the bottom of the inner wall of the container, i.e., the temperature sensed by the flounder; and the bottom layer temperature is the temperature of the water layer where the flounder is located.

4. The welfare screening method for heat-resistant flounder according to claim 1, characterized in that, In step S3, 55-day-old or older flounder are placed in a cubic transparent container with controllable temperature rise and fall 2 hours in advance. The temperature is set to be gradually heated or cooled every half hour at a rate of 3-5°C, so that the bottom water temperature is raised from the optimal culture temperature of flounder to below the lethal temperature of flounder, or cooled from the optimal culture temperature of flounder to above the lethal temperature of flounder.

5. The welfare screening method for heat-resistant flounder according to claim 4, characterized in that, The bottom water temperature rises or falls by 5°C every 35 minutes.

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