Method for screening comprehensive stress-resistant crabs

Abstract

The invention discloses a comprehensive stress-resistant crab screening method which comprises the following steps: preparing a breeding system, monitoring a breeding environment, putting to-be-screened adult crabs into the breeding system for temporary breeding after the breeding environment is monitored to be qualified, and ensuring that the crabs are not subjected to external stress; and sequentially screening the ingestion recovery speed and the defense behavior after stress, and selecting high-quality crab parents for breeding. By means of a behavioral physiology method, the scientific and reasonable screening method is designed by means of the fact that the growth state, ingestion recovery after stress and defense behaviors of the crabs are closely related to individual environment adaptability, healthy crabs high in stress resistance and appetite can be simply, rapidly and efficiently obtained, and the screening method has important significance on sustainable breeding of the crabs.

Description

Technical Field

[0001] The invention belongs to the technical field of aquaculture, and particularly relates to a screening method for comprehensive stress-resistant crabs. Background Art

[0002] In recent years, with the development and utilization of aquatic resources and space, the aquaculture ecosystem has continued to deteriorate, and aquaculture disasters have occurred frequently. In addition, the decline of germplasm resources has caused huge losses to the aquaculture industry. Crabs are an important target of my country's fishery and aquaculture, providing humans with a large amount of high-quality protein. In the normal breeding process of crabs, it is inevitable to encounter various environmental changes and human coercion. The survival rate of crab breeding has dropped from the original 80% to 20-40%. The "weak or sub-healthy" individuals in the breeding group will have anorexia and become ill first, and infect the entire group, causing large-scale disasters. Therefore, breeding a strong and lively group can avoid the occurrence of breeding disasters. The breeding of a strong group also provides a group with strong resistance to stress for further screening of quality and other traits, improves the breeding rate of resistance to stress, and reduces breeding costs. Summary of the invention

[0003] In view of the above problems, the purpose of the present invention is to provide a screening method for comprehensive stress-resistant crabs, which can realize simple and efficient screening of crab health status, is suitable for providing high-quality breeding parents for crab apartment or cage farming and ecological farming, and promotes the healthy and sustainable development of the crab farming industry.

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

[0005] The present invention provides a method for screening comprehensive stress-resistant crabs, comprising the following steps:

[0006] S1: The aquaculture system is first disinfected with disinfectant, then rinsed and soaked with fresh water, and then injected with fully aerated fresh water or natural seawater;

[0007] S2: Monitor the aquaculture environment of the aquaculture system until it meets the aquaculture index requirements and obtains a qualified recirculating aquaculture system;

[0008] S3: marking the carapace of the crabs, soaking and disinfecting the adult crabs to be screened with aquaculture water containing povidone iodine, then washing with spare aquaculture water, and then placing them into the qualified circulation aquaculture system described in step S2;

[0009] S4: Select healthy individuals with high fatness from crabs of the same age as those in step S3;

[0010] S5: For the crabs selected in step S4, the appetite recovery speed after air exposure stress is used to select healthy individuals with fast appetite recovery after stress, and the crabs are allowed to recover for several hours;

[0011] S6: For the crabs screened out in step S5, the defensive behaviors of the crabs when attacked are used to screen healthy and brave individuals that defend on the spot, thereby completing the screening of crabs.

[0012] Preferably, the crab species include Chinese mitten crab and swimming crab.

[0013] Preferably, in step S1, the disinfectant is bleaching powder, wherein the effective residual chlorine should be greater than 30 ppm; the number of fresh water rinses is more than 3 times, and the fresh water soaking time is more than 1 day.

[0014] Preferably, in step S2, the pre-set environmental indicators for breeding are: water temperature of 15-25°C, daylight hours and dark hours of 12 hours respectively, pH value of 7.5-9.5, dissolved oxygen concentration ≥5 mg / L, total ammonia nitrogen ≤0.5 mg / L, and nitrite concentration ≤0.05 mg / L.

[0015] Preferably, in step S3, the concentration of povidone iodine is 20-40.0 mg / L, the dissolved oxygen concentration is ≥5 mg / L, and the soaking time is 20-30 min; the density of crabs introduced into the breeding system is 5-10 / m 2 The spare aquaculture water for immersion is aquaculture water that has been aerated with an aeration pump for more than two weeks, and the immersion time is 0.5 to 1 hour.

[0016] Preferably, in step S4, the healthy individuals with high individual fatness are: the crabs of the same age to be screened in step S3 are weighed one by one, the weight and appearance characteristics of the crabs are recorded, the weight values ​​are arranged from large to small, and the healthy individuals in the top third by weight with full vitality, sound feet and no damage on the body surface are selected for subsequent screening.

[0017] Preferably, in step S5, the method for screening the appetite recovery rate after air exposure stress is: take the crabs out of the culture system, catch them in the air with a net and expose them for 10 minutes; before the start of feeding, place the food on one side (long end) of the test water tank (40 cm long and 20 cm wide), and place the crabs alone on the other side of the test water tank, measure the time when the crabs first reach the food and start feeding, arrange the time from small to large, and select healthy individuals in the first third of the feeding time for subsequent screening.

[0018] Preferably, in step S6, the method for screening the defensive behavior of crabs under attack conditions is: placing the crab in the middle of the test box, fixing the bionic crab on one end of a thin wooden stick and approaching the crab to be tested from far to near or clicking on one end of the box to imitate the sound of footsteps from far to near, while observing and recording the defensive behavior of the crab, selecting healthy and brave individuals whose chelae are forward and whose chelae are open at an angle of more than 60° and whose duration is more than 6 seconds for defense in situ, and abandoning sensitive and timid individuals whose response is not defensive and whose moving distance of fleeing in the opposite direction is greater than their body length, and the screening ends here.

[0019] The present invention adopts the above technical solution and has the following beneficial effects:

[0020] (1) The present invention utilizes the characteristics related to individual physiological behavior and environmental adaptability, and screens crabs based on the principle that crabs with different health conditions, growth and development status, and stress recovery characteristics have different stress recovery times and stress coping methods after being subjected to various stimuli from the external environment.

[0021] (2) By utilizing the different responses of crabs to stress behaviors, the individuals that are sensitive to stress, those that are not easy to recover from, and those with weak constitutions can be separated from the crab population, thereby ensuring the crab population's ability to resist stress and achieving the goal of healthy breeding and promoting growth.

[0022] (3) The fatness and external morphological characteristics of crab growth were used as the first indicator for screening crab stress resistance. The feeding recovery of individual crabs after fishing, small bright space, and loneliness stress was used as the second indicator for screening crab stress resistance. The movement and defense behavior of crabs in the presence of external threats was used as the third indicator for screening crab stress resistance.

[0023] (4) The crab's anti-stress performance is closely related to its disease resistance. The healthy individuals selected can reduce the occurrence of diseases and improve the survival rate. The crab individuals selected by the present invention have the characteristics of strong overall stress resistance.

[0024] (5) The present invention selects healthy individuals with stress resistance, strong appetite and fast growth for breeding through multiple rounds of screening, which is beneficial to optimize the breeding structure, improve the breeding efficiency, and is suitable for large-scale aquaculture.

[0025] (6) The equipment required by the present invention is simple and the operation is convenient and quick. The screening method adopted can be implemented in general crab breeding sites and is highly practical, especially suitable for providing high-quality breeding parents for crab apartment or cage breeding and ecological breeding.

[0026] In summary, the present invention proposes a method for screening healthy crab individuals that are resistant to stress. The method utilizes the principle that the fatness and morphological observation of crabs, the recovery of appetite after stress, and the motor defense behavior under stress are closely related to the disease infection stress of crabs. The method adopts a method of multiple screening and elimination of weak and inactive individuals. Crab individuals that are resistant to stress and have a strong appetite are screened out from the general crab population to establish a breeding parent population, thereby maintaining the brave and healthy advantages of the offspring crab population and improving the breeding yield and survival rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 These are the survival rate test results of the offspring of the Chinese mitten crabs that defend in situ, actively attack forward, and escape backwards, screened in Example 1.

[0028] Figure 2 These are the test results of the average weight gain rate of the offspring of the Chinese mitten crabs that defend in situ, attack forward actively, and escape backwards, which were screened in Example 1.

[0029] Figure 3 These are the survival rate test results of the offspring of the swimming crabs that defended in situ, actively attacked forward, and escaped backward at a salinity of 8, which were screened in Example 2. DETAILED DESCRIPTION

[0030] The technical scheme of the present invention is further described below by way of examples. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0031] The present invention utilizes the characteristics related to individual physiological and behavioral responses and environmental adaptability, and conducts multiple screenings on crabs based on the principle that crabs with different health conditions, growth and development states, and stress recovery characteristics have different recovery times and stress performances when exposed to various external stimuli. Crabs with good physique and courage can recover quickly in a short period of time after being stimulated by air exposure, and start to eat. When external threats exist, they will adopt a defensive response method in situ; crabs with poor physique and low activity cannot recover quickly in a short period of time after being severely stimulated by air exposure, and will not start to eat in a short period of time. When external threats exist, they will adopt a defensive response method of escape. Scientific and reasonable detection methods are used during screening to avoid the death of crabs due to excessive screening intensity, and to accurately select healthy and lively crabs.

[0032] The present invention is explained below in conjunction with implementation examples.

[0033] Example 1

[0034] This embodiment provides a method for screening comprehensive stress-resistant Chinese mitten crabs, the steps are as follows:

[0035] S1. The aquaculture system is disinfected with a bleaching powder disinfectant with a residual chlorine content of 30 ppm, then rinsed with fresh water and soaked for 1 day, rinsed with fresh water 3 times, and injected with fully aerated fresh water.

[0036] S2. Monitor the breeding environment of the breeding system to ensure that it meets the pre-set environmental indicators: water temperature is 18-25℃, daylight and dark time are 12h respectively, pH value is 7.5-9.5, dissolved oxygen concentration is ≥6mg / L, total ammonia nitrogen is ≤0.2mg / L, and nitrite concentration is ≤0.01mg / L.

[0037] S3. After marking the carapace of Chinese mitten crab, the adult Chinese mitten crab to be screened is immersed in aquaculture water containing 30.0 mg / L povidone iodine for disinfection for 30 minutes, then immersed in aquaculture water aerated for more than two weeks with an aeration pump for 0.5 hours, and then placed in the qualified aquaculture system in step S2; wherein the dissolved oxygen concentration of the aquaculture water containing 30.0 mg / L povidone iodine is 6 mg / L, and the stocking density of the Chinese mitten crab introduced into the aquaculture system is 5-10 crabs / m 2 .

[0038] S4. Weigh the Chinese mitten crabs of the same age to be screened in step S3 one by one, record their weight and appearance characteristics, arrange the weight values ​​from large to small, and screen out healthy individuals that are in the top third by weight and have abundant vitality, sound feet, and no body surface damage.

[0039] S5. For the Chinese mitten crabs screened out in step S4, active and healthy individuals with fast appetite recovery after stress are screened out by using the speed of appetite recovery after air exposure stress, and then they are allowed to recover for several hours; initially, the Chinese mitten crabs are taken out of the culture system by netting, exposed to the air for 10 minutes, and placed in a test water tank to measure the feeding recovery speed; before the start of feeding, food is placed on one side (long end) of the test water tank (40 cm long and 20 cm wide), and the Chinese mitten crabs are placed alone on the other side of the test water tank, and the time when the Chinese mitten crabs first reach the food and start feeding is measured, the time is arranged from small to large, and healthy individuals in the first third of the feeding time are selected for subsequent screening.

[0040] S6, for the Chinese mitten crab screened out in step S5, the defensive behavior of the Chinese mitten crab under the condition of being attacked is used to screen out healthy and brave individuals that defend in situ, and then allow them to recover for several hours; at the beginning, the Chinese mitten crab is taken out of the breeding system and placed in the middle of the test box, the bionic crab is fixed on one end of a thin wooden stick to approach the Chinese mitten crab to be tested from far to near or click on one end of the box to imitate the sound of footsteps from far to near, and the defensive behavior of the Chinese mitten crab is observed and recorded at the same time, and the healthy individuals whose chelae are forward for defense in situ and whose chelae are opened at an angle of more than 60° and whose duration is more than 8 seconds are selected, and the sensitive individuals whose moving distance of escaping in the opposite direction is greater than their body length are abandoned, and the screening ends here.

[0041] Example 2

[0042] This embodiment provides a method for screening comprehensive stress-resistant swimming crabs, the steps are as follows:

[0043] S1. The aquaculture system is disinfected with a bleaching powder disinfectant with a residual chlorine content of 30 ppm, then rinsed with fresh water and soaked for 1 day, rinsed with fresh water 3 times, and injected with fully aerated natural seawater.

[0044] S2. Monitor the breeding environment of the breeding system to ensure that it meets the pre-set environmental indicators: water temperature is 20-25℃, daylight and dark time are 12h respectively, pH value is 7.8-8.5, dissolved oxygen concentration is ≥6mg / L, total ammonia nitrogen is ≤0.3mg / L, and nitrite concentration is ≤0.01mg / L.

[0045] S3. After marking the carapace of the swimming crab, the adult swimming crabs to be screened are immersed in aquaculture water containing 30.0 mg / L povidone iodine for disinfection for 30 minutes, then washed with aquaculture water aerated for more than two weeks using an aeration pump for 0.5 hours, and then placed in the qualified aquaculture system in step S2; wherein the dissolved oxygen concentration of the aquaculture water containing 30.0 mg / L povidone iodine is 6 mg / L, and the stocking density of the swimming crabs introduced into the aquaculture system is 5-10 crabs / ㎡.

[0046] S4. Weigh the swimming crabs of the same age to be screened in step S3 one by one, record the weight and appearance characteristics of the swimming crabs, arrange the weight values ​​from large to small, and screen out healthy individuals that are in the top third by weight and have full vitality, sound feet, and no damage on the body surface.

[0047] S5. For the swimming crabs screened out in step S4, active and healthy individuals with fast appetite recovery after stress are screened out by using the speed of appetite recovery after air exposure stress, and then they are allowed to recover for several hours; initially, the swimming crabs are taken out of the culture system by netting, exposed to the air for 10 minutes, and placed in a test water tank to measure the feeding recovery speed; before the start of feeding, food is placed on one side (long end) of the test water tank (40 cm long and 20 cm wide), and the swimming crabs are placed alone on the other side of the test water tank, and the time when the swimming crabs first reach the food and start feeding is measured, the time is arranged from small to large, and healthy individuals in the first third of the feeding time are selected for subsequent screening.

[0048] S6. For the swimming crabs screened out in step S5, the defense behavior of the swimming crabs under attack is used to screen out healthy and brave individuals that defend in situ, and then allow them to recover for several hours; at the beginning, the swimming crabs are taken out of the breeding system and placed in the middle of the test box, and the bionic crab is fixed on one end of a thin wooden stick to approach the swimming crab to be tested from far to near or click on one end of the box to imitate the sound of footsteps from far to near, and the defense behavior of the swimming crabs is observed and recorded at the same time, and healthy individuals whose chelae are forward and whose chelae are opened at an angle of more than 60° and whose duration is more than 6 seconds are selected for defense in situ, and sensitive individuals whose moving distance of escaping in the opposite direction is greater than their body length are abandoned, and the screening ends here.

[0049] Test Results

[0050] Taking Example 1 as the test sample, the effects of other embodiments are similar to those of Example 1.

[0051] The screening method for comprehensive stress-resistant crabs of the present invention is used to select Chinese mitten crab individuals that defend in situ, Chinese mitten crab individuals that actively attack in the forward direction (attack defense) and Chinese mitten crab individuals that escape in the reverse direction (escape defense), and their offspring, and sixteen of each are selected for stress resistance testing.

[0052] (1) Survival test of the offspring of Chinese mitten crabs that defended in situ, attacked forward, and fled backward

[0053] The test results are as follows Figure 1 As shown, it can be seen that the offspring of Chinese mitten crabs that were screened out for in situ defense have stronger survival ability.

[0054] (2) Test on the average weight gain rate of the offspring of the selected Chinese mitten crabs that defend in situ, attack positively, and escape reversely

[0055] The test results are as follows Figure 2 As shown, it can be seen that the offspring individuals of Chinese mitten crab that were screened out for in-situ defense had a higher average weight gain rate than the offspring individuals of Chinese mitten crab that actively attacked forward and fled backward.

[0056] Using Example 2 as the test sample, the effects of other examples are similar to those of Example 2.

[0057] The screening method for comprehensive stress-resistant crabs of the present invention is used to select the three-spotted swimming crab individuals that defend in situ, the three-spotted swimming crab individuals that actively attack forward (attack defense) and escape backward (escape defense), and their offspring, and sixteen of each are selected for stress resistance testing.

[0058] (3) Survival test of the selected offspring of the swimming crabs defending in situ, attacking positively, and escaping reversely at a salinity of 8

[0059] The test results are as follows Figure 3 As shown, it can be seen that the offspring individuals of the swimming crab selected for in-situ defense have stronger salinity tolerance than the offspring individuals of the swimming crab that are sensitive to positive active attack and reverse escape.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the scope of the technical solution of the present invention.

Claims

1. A method for screening comprehensive stress-resistant crabs, characterized in that: The following steps are involved: S1: The aquaculture system is first disinfected with disinfectant, then rinsed and soaked with fresh water, and then injected with fully aerated fresh water or natural seawater; S2: Monitor the aquaculture environment of the aquaculture system until it meets the aquaculture index requirements and obtains a qualified recirculating aquaculture system; S3: marking the carapace of the crabs, soaking and disinfecting the adult crabs to be screened with aquaculture water containing povidone iodine, then washing with spare aquaculture water, and then placing them into the qualified circulation aquaculture system described in step S2; S4: Select healthy individuals with high fatness from crabs of the same age as those in step S3; S5: For the crabs selected in step S4, the appetite recovery speed after air exposure stress is used to select healthy individuals with fast appetite recovery after stress, and the crabs are allowed to recover for several hours; S6: For the crabs screened out in step S5, the defensive behaviors of the crabs when attacked are used to screen healthy and brave individuals that defend on the spot, thereby completing the screening of crabs.

2. The method for screening comprehensive stress-resistant crabs according to claim 1, characterized in that: The species of crabs include Chinese mitten crab and swimming crab.

3. The screening method for comprehensive stress-resistant crabs according to claim 1, characterized in that: In step S1, the disinfectant is bleaching powder, in which the effective residual chlorine should be greater than 30 ppm; the number of fresh water rinses is more than 3 times, and the fresh water soaking time is more than 1 day.

4. The method for screening comprehensive stress-resistant crabs according to claim 1, characterized in that: In step S2, the pre-set environmental indicators for breeding are: water temperature of 15-25°C, daylight hours and dark hours of 12 hours respectively, pH value of 7.5-9.5, dissolved oxygen concentration ≥5 mg / L, total ammonia nitrogen ≤0.5 mg / L, and nitrite concentration ≤0.05 mg / L.

5. The method for screening comprehensive stress-resistant crabs according to claim 1, characterized in that: In step S3, the concentration of povidone iodine is 20-40.0 mg / L, the dissolved oxygen concentration is ≥5 mg / L, and the soaking time is 20-30 min; the density of crabs introduced into the breeding system is 5-10 / m 2 The spare aquaculture water for immersion is aquaculture water that has been aerated with an aeration pump for more than two weeks, and the immersion time is 0.5 to 1 hour.

6. The method for screening comprehensive stress-resistant crabs according to claim 1, characterized in that: In step S4, the healthy individuals with high individual fatness are: the crabs of the same age to be screened in step S3 are weighed one by one, the weight and appearance characteristics of the crabs are recorded, the weight values ​​are arranged from large to small, and the healthy individuals in the top third by weight with full vitality, sound feet and no damage on the body surface are selected for subsequent screening.

7. The method for screening comprehensive stress-resistant crabs according to claim 1, characterized in that: In step S5, the method for screening the appetite recovery rate after air exposure stress is as follows: the crabs are taken out of the culture system, caught in a net and exposed to the air for 10 minutes; before the start of feeding, the food is placed on one side of the long end of the test water tank, and the crabs are placed alone on the other side of the test water tank, and the time when the crabs first reach the food and start feeding is measured, and the time is arranged from small to large, and healthy individuals in the first third of the feeding time are selected for subsequent screening.

8. The method for screening comprehensive stress-resistant crabs according to claim 1, characterized in that: In step S6, the method for screening the defensive behavior of crabs under attack conditions is as follows: placing the crab in the middle of the test box, fixing the bionic crab on one end of a thin wooden stick and approaching the crab to be tested from far to near, or clicking one end of the box to imitate the sound of footsteps from far to near, while observing and recording the defensive behavior of the crab, selecting healthy and brave individuals whose chelae are facing forward and whose chelae are opened at an angle of more than 60° and whose duration is more than 6 seconds, and abandoning sensitive and timid individuals whose movement distance of not defending and fleeing in the opposite direction is greater than their body length, and the screening ends here.

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