A method for selecting fast-growing Pelteobagrus vachelli with low oxygen tolerance

Abstract

The present invention relates to a method for selecting Pseudobagrus vachelli with fast growth under low oxygen tolerance, belonging to the technical field of fishery science applications. The selection method of the present invention is based on a low oxygen stress screening device with a culture barrel, and the operation steps are as follows: (1) Establish at least 200 full-sib families of Pseudobagrus vachelli; (2) Preset the oxygen reduction stress conditions. When the dissolved oxygen in the water body remains at 5 mg / L or above, reduce the dissolved oxygen in the water body by 0.5 mg / L every 2 hours until 50% of the fish suffocate to death, and record the semi-lethal dissolved oxygen value at this time; (3) For more than 200 families, conduct size and low oxygen stress screening at the summer fingerling stage, 1-year-old fingerling stage, 2-year-old fingerling stage, and 3-year-old fish stage respectively. The selected full-sib families are cultivated as breeding parents; Carry out paired breeding among the selected full-sib families. The offspring obtained have stronger low oxygen tolerance and better growth performance than the previous generation. The screening method of the present invention improves the breeding density and production efficiency per unit area of Pseudobagrus vachelli.

Description

Technical Field

[0001] The invention belongs to the technical field of fishery science application, and in particular relates to a method for selecting yellow catfish with low oxygen tolerance and fast growth. Background Art

[0002] At present, the common yellow catfish breeding varieties on the market include common yellow catfish, Pelteobagrus vachelli and hybrid yellow catfish. Common yellow catfish has a small market share due to its slow growth rate and small size of adult fish. Pelteobagrus vachelli has tender meat and delicious taste. It grows faster than common yellow catfish and has large size of adult fish. It is an important breeding variety in the yellow catfish industry, but its tolerance to hypoxia is low. It is prone to hypoxia and death during breeding, causing economic losses, which restricts the breeding and promotion of Pelteobagrus vachelli to a certain extent. Hybrid yellow catfish is the main breeding variety in the yellow catfish industry. It is a hybrid of common yellow catfish as the female parent and Pelteobagrus vachelli as the male parent. It inherits a set of chromosomes from each parent. It is a true hybrid. In the hybridization process, a small amount of male parent is matched with a large amount of female parent. It can be seen that the germplasm quality of the male parent has a decisive influence on the offspring. Therefore, selecting hypoxia-tolerant and fast-growing Pelteobagrus vachelli is crucial to the development of the yellow catfish industry. So how to breed a population of hypoxia-tolerant and fast-growing Pelteobagrus vachelli is a key technical problem that needs to be solved urgently. Summary of the invention

[0003] In order to solve the problem that Pelteobagrus vachelli has low hypoxia tolerance and is prone to hypoxia death during breeding, the present invention provides a method for selecting Pelteobagrus vachelli that is hypoxia tolerant and grows fast.

[0004] A method for selecting yellow catfish with low oxygen tolerance and fast growth, comprising a low oxygen stress screening device, and the specific selection operation steps are as follows:

[0005] (1) Establish at least 200 full-sib families of Pelteobagrus vachelli

[0006] (1.1) Select more than 200 female and male Pelteobagrus vachelli with well-developed gonads from aquatic breeding farms or natural waters such as rivers, lakes, etc. as breeding parents, and the size of male fish should not be less than 400g and the size of female fish should not be less than 200g;

[0007] (1.2) Carry out breeding with one male and one female in pairs, and the offspring produced will be a full-sib family. A total of more than 200 full-sib families will be established. Each full-sib family will be cultivated separately and will not be mixed with other families;

[0008] (2) Preset hypoxia stress conditions

[0009] (2.1) First, oxygenate the water in the culture tank 1 of the hypoxia stress screening device until the dissolved oxygen content of the water is maintained at 5 mg / L or above;

[0010] Reduce the dissolved oxygen content in the water body by 0.5 mg / L every 2 hours;

[0011] (2.3) Observe the activities of the fish in real time, record the time, quantity of fish suffocation death and the dissolved oxygen at that time until 50% of the fish suffocate to death, and record the semi-lethal dissolved oxygen value at this time;

[0012] (3) For more than 200 families, conduct hypoxia stress screening at the summer fingerling stage, 1-year-old fingerling stage, 2-year-old fingerling stage, and 3-year-old fish stage respectively, select hypoxia-tolerant individuals, cultivate the hypoxia-tolerant individuals in the next stage, and at the same time eliminate individuals that are not hypoxia-tolerant;

[0013] (3.1) Screening at the summer fingerling stage

[0014] The summer fingerlings are the fry about one month after hatching. Transfer all the fry of the same full-sib family into the hypoxia stress device, reduce the dissolved oxygen in the water body according to step (2) until 50% of the fry die, record the semi-lethal dissolved oxygen value at this time, end the stress, restore the normal dissolved oxygen level, and fish out the dead individuals;

[0015] Sort more than 200 full-sib families in ascending order of the semi-lethal dissolved oxygen value, select the top 50% of the most hypoxia-tolerant families, and continue to cultivate them separately to 1-year-old fingerlings;

[0016] (3.2) Screening at the 1-year-old fingerling stage

[0017] Select the female and male fish in the top 50% of each full-sib family in terms of size, then transfer them into the hypoxia stress device together and conduct screening according to step (2); Sort more than 200 full-sib families in ascending order of the semi-lethal dissolved oxygen value, select the top 50% of the most hypoxia-tolerant families, and continue to cultivate them separately to 2-year-old fingerlings;

[0018] (3.3) Screening at the 2-year-old fingerling stage

[0019] Select the female and male fish in the top 50% of each full-sib family in terms of size, then transfer them into the hypoxia stress device together and conduct screening according to step (2); Sort more than 200 full-sib families in ascending order of the semi-lethal dissolved oxygen value, select the top 25% of the most hypoxia-tolerant families, and continue to cultivate them separately to 3-year-old fish;

[0020] (3.4) Screening at the 3-year-old fish stage

[0021] Select the female and male fish in the top 50% of the specifications in each full-sib family, and then transfer them together into the hypoxia stress device, and conduct screening according to step (2) to obtain the selected full-sib families for cultivation as breeding parents; carry out paired breeding among the selected full-sib families, and the offspring obtained have stronger hypoxia tolerance and better growth performance than the previous generation.

[0022] The technical solution of the further method for selecting Pseudobagrus vachelli is as follows:

[0023] In step (2.2), the specific operation of reducing the dissolved oxygen content in the water body by 0.5 mg / L every 2 hours: turn down the valve of the oxygen cylinder, turn up the valve of the nitrogen cylinder, and observe the change of the value of the dissolved oxygen meter until the dissolved oxygen value is stable.

[0024] In step (3.2), the 1-year-old fish species are fish species at 12 months old. Separate the female and male fish in each full-sib family of 1-year-old fish species for temporary cultivation. Select the individuals of female fish in the top 50% of the specifications and the individuals of male fish in the top 50% of the specifications respectively, and then place the selected female and male fish together in the hypoxia stress device. According to step (2), reduce the dissolved oxygen content in the water body until 50% of the individuals die, record the semi-lethal dissolved oxygen value, end the stress, restore the normal dissolved oxygen level, and fish out the dead individuals; sort according to the semi-lethal dissolved oxygen value from low to high, and select the top 50% of the families with the highest hypoxia tolerance, and continue to cultivate them separately until they reach 2-year-old fish species.

[0025] In step (3.3), the 2-year-old fish species are fish species at 24 months old. Select the individuals of female fish in the top 50% of the specifications and the individuals of male fish in the top 50% of the specifications in each full-sib family of 2-year-old fish species, and then place the selected female and male fish together in the hypoxia stress device. According to step (2), reduce the dissolved oxygen content in the water body until 50% of the individuals die, record the semi-lethal dissolved oxygen value, end the stress, restore the normal dissolved oxygen level, and fish out the dead individuals; sort according to the semi-lethal dissolved oxygen value from low to high, and select the top 25% of the families with the highest hypoxia tolerance, and continue to cultivate them separately until they reach 3-year-old fish.

[0026] In step (3.4), the 3-year-old fish species are fish at 36 months old. At this time, the fish are in good sexual maturity and can be used as broodstock to breed offspring; before being used as breeding parents, the same hypoxia stress screening is carried out. Select the individuals of female fish in the top 50% of the specifications and the individuals of male fish in the top 50% of the specifications in each full-sib family of 3-year-old fish species respectively, and then place the selected female and male fish together in the hypoxia stress device. According to step (2), reduce the dissolved oxygen content in the water body until 50% of the fish species die, record the semi-lethal dissolved oxygen value, end the stress, restore the normal dissolved oxygen level, and fish out the dead individuals; use the hypoxia-tolerant Pseudobagrus vachelli as breeding parents for cultivation.

[0027] A hypoxia stress screening device for selecting Pseudobagrus vachelli includes a culture barrel 1. An aeration disc 2 is provided at the bottom inside the culture barrel 1. The aeration disc 2 is connected through a hose to an oxygen cylinder 3 and a nitrogen cylinder 4 in parallel. A mesh grille 5 is provided at the upper part inside the culture barrel 1. The mesh of the mesh grille 5 is smaller than the width of the head of the fish species to be put in, preventing the fish head from floating out of the water surface;

[0028] When water is filled in the culture barrel 1, the mesh grille 5 is located at the liquid level, and a dissolved oxygen measurement probe 6 is arranged in the water body.

[0029] The technical solution of the further hypoxia stress screening device is as follows:

[0030] The culture barrel 1 has a diameter of 0.6 m and a height of 1.0 m.

[0031] The aeration disc 2 is a circular ceramic aeration disc.

[0032] The oxygen cylinder 3 and the nitrogen cylinder 4 both have a volume of 40 L.

[0033] The beneficial technical effects of the present invention are reflected in the following aspects:

[0034] The method for selecting Pseudobagrus vachelli of the present invention improves the breeding density and production efficiency of Pseudobagrus vachelli. The Pseudobagrus vachelli that is tolerant to low oxygen and grows fast can survive in the water body with relatively low dissolved oxygen, reducing the death and stress response caused by hypoxia, thereby increasing the breeding density per unit area. At the same time, the fast-growing variety can reach the market specification faster, and the breeding cycle is shortened by 4 to 5 months.

[0035] The selected Pseudobagrus vachelli of the present invention has the dual economic traits of being tolerant to low oxygen and growing fast, and this trait is a high-quality gene that can be inherited, which can provide excellent germplasm resources for the seed production of hybrid yellow catfish (yellow catfish ♀×Pseudobagrus vachelli♂).

[0036] The selected Pseudobagrus vachelli that is tolerant to low oxygen of the present invention reduces the dependence on oxygen-increasing equipment and can reduce carbon emissions, meeting the trend of green breeding and low-carbon economy.

[0037] Through multiple stress screenings, the present invention eliminates the families and individuals that are not tolerant to low oxygen and grow slowly, reducing the conservation cost by 80% and greatly reducing the conservation pressure. Description of the Drawings

[0038] Figure 1 It is a schematic diagram of the hypoxia stress device;

[0039] Figure 2 It is a selection route map for different growth stages of Pseudobagrus vachelli;

[0040] Figure 3 It is a Tunel result diagram of the gill tissue of Pseudobagrus vachelli under hypoxia stress.

[0041] Figure 1 Serial numbers in the figure: breeding barrel 1, aeration disc 2, oxygen cylinder 3, nitrogen cylinder 4, mesh grille 5, dissolved oxygen measurement probe 6. Specific implementation mode

[0042] The present invention will be further described below with reference to the accompanying drawings through examples.

[0043] Example 1

[0044] See Figure 1 , the hypoxia stress screening device for selecting Pseudobagrus vachelli includes a breeding barrel 1 with a diameter of 0.6 m and a height of 1.0 m. A circular ceramic aeration disc 2 is provided at the bottom inside the breeding barrel 1, and the aeration disc 2 is connected through a hose to an oxygen cylinder 3 and a nitrogen cylinder 4 connected in parallel. The oxygen cylinder 3 and the nitrogen cylinder 4 both have a volume of 40 L. A mesh grille 5 is installed in the upper part inside the breeding barrel 1, and the mesh of the mesh grille 5 is smaller than the head width of the fish species to be put in, preventing the fish head from floating out of the water surface;

[0045] When the breeding barrel 1 is filled with water, the mesh grille 5 is located at the liquid level, and a dissolved oxygen measurement probe 6 is installed in the water body of the breeding barrel 1.

[0046] Example 2

[0047] See Figure 2 , the selection operation steps for Pseudobagrus vachelli with fast growth under low oxygen tolerance are as follows:

[0048] (1) Establish 220 full-sib families of Pseudobagrus vachelli

[0049] (1.1) On May 31, 2021, Pseudobagrus vachelli parents were introduced from Lu'an Huarun Technology Aquaculture Co., Ltd. (Anhui Provincial Pseudobagrus vachelli Provincial Breeding Farm) to carry out full-sib family breeding.

[0050] Select 3-year-old Pseudobagrus vachelli as breeding parents, with 258 male fish, with an average size of 510 g, and 258 female fish, with an average size of 260 g.

[0051] (1.2) Carry out one-male-one-female paired breeding, and the offspring produced are a full-sib family. A total of 220 full-sib families are established, and each full-sib family is separately cultivated without mixing with other families, and cultivated into summer flower fish species.

[0052] (2) Preset hypoxia stress conditions

[0053] (2.1) First, oxygenate the water body in the breeding barrel 1 of the hypoxia stress screening device until the dissolved oxygen in the water body remains at 5 mg / L or above;

[0054] (2.2) Reduce the dissolved oxygen in the water body by 0.5 mg / L every 2 hours;

[0055] (2.3) Observe the activities of fish in real time, record the time, quantity of fish suffocating to death and the dissolved oxygen at that time until 50% of the fish suffocate to death, and record the semi-lethal dissolved oxygen value at this time.

[0056] (3) For 220 full-sib families, conduct hypoxia stress screening at the summer fingerling stage, 1-year-old fingerling stage, 2-year-old fish stage, and 3-year-old fish stage respectively, screen out hypoxia-tolerant individuals, cultivate the hypoxia-tolerant individuals in the next stage, and eliminate the hypoxia-intolerant individuals at the same time; the specific operations are as follows:

[0057] (3.1) Screening at the summer fingerling stage

[0058] On July 2, 2021, first aerate the water body in the culture barrel of the hypoxia stress device until the dissolved oxygen in the water body is maintained at 5 mg / L, and then transfer the summer fingerlings of Pelteobagrus vachelli from the same full-sib family into culture barrel 1 of the hypoxia stress device for temporary cultivation. Every 2 hours later, adjust the valve of the oxygen cylinder smaller and the valve of the nitrogen cylinder larger to reduce the dissolved oxygen in the water body by 0.5 mg / L and keep it stable. Observe the activities of the fish in the culture barrel in real time, record the time, quantity of fish suffocating to death and the dissolved oxygen at that time until 50% of the fish suffocate to death, record the semi-lethal dissolved oxygen value at this time, end the stress, restore the normal dissolved oxygen level, fish out the dead individuals, and transfer the surviving individuals back to the nursery pond for continued cultivation. When 220 full-sib families have all undergone hypoxia stress screening, sort the 220 full-sib families according to the semi-lethal dissolved oxygen value from low to high, screen out the 112 families with the lowest semi-lethal dissolved oxygen value, and continue to cultivate them separately until they reach 1-year-old fingerlings.

[0059] Table 1 The top 50% of families with hypoxia tolerance at the summer fingerling stage (112 families)

[0060] Serial number Number Semi-lethal dissolved oxygen level (mg / L) Serial number Number Semi-lethal dissolved oxygen level (mg / L) Serial number Number Semi-lethal dissolved oxygen level (mg / L) Serial number Number Semi-lethal dissolved oxygen level (mg / L) 1 Family 18 0.55 31 Family 83 0.58 61 Family 88 0.6 91 Family 173 0.63 2 Family 29 0.55 32 Family 160 0.58 62 Family 115 0.6 92 Family 188 0.63 3 Family 72 0.55 33 Family 176 0.58 63 Family 211 0.6 93 Family 217 0.63 4 Family 97 0.55 34 Family 189 0.58 64 Family 212 0.6 94 Family 10 0.64 5 Family 148 0.55 35 Family 219 0.58 65 Family 3 0.61 95 Family 53 0.64 6 Family 169 0.55 36 Family 16 0.59 66 Family 32 0.61 96 Family 95 0.64 7 Family 170 0.55 37 Family 38 0.59 67 Family 55 0.61 97 Family 96 0.64 8 Family 204 0.55 38 Family 51 0.59 68 Family 94 0.61 98 Family 112 0.64 9 Family 6 0.56 39 Family 54 0.59 69 Family 108 0.61 99 Family 132 0.64 10 Family 22 0.56 40 Family 61 0.59 70 Family 110 0.61 100 Family 143 0.64 11 Family 69 0.56 41 Family 62 0.59 71 Family 117 0.61 101 Family 199 0.64 12 Family 75 0.56 42 Family 66 0.59 72 Family 131 0.61 102 Family 218 0.64 13 Family 91 0.56 43 Family 67 0.59 73 Family 152 0.61 103 Family 5 0.65 14 Family 92 0.56 44 Family 82 0.59 74 Family 157 0.61 104 Family 9 0.65 15 Family 103 0.56 45 Family 84 0.59 75 Family 213 0.61 105 Family 41 0.65 16 Family 106 0.56 46 Family 86 0.59 76 Family 30 0.62 106 Family 60 0.65 17 Family 111 0.56 47 Family 90 0.59 77 Family 78 0.62 107 Family 93 0.65 18 Family 134 0.56 48 Family 113 0.59 78 Family 79 0.62 108 Family 99 0.65 19 Family 138 0.56 49 Family 129 0.59 79 Family 123 0.62 109 Family 100 0.65 20 Family 186 0.56 50 Family 164 0.59 80 Family 124 0.62 110 Family 135 0.65 21 Family 202 0.56 51 Family 178 0.59 81 Family 141 0.62 111 Family 149 0.65 22 Family 70 0.57 52 Family 179 0.59 82 Family 146 0.62 112 Family 206 0.65 23 Family 81 0.57 53 Family 187 0.59 83 Family 147 0.62 24 Family 102 0.57 54 Family 196 0.59 84 Family 163 0.62 25 Family 109 0.57 55 Family 200 0.59 85 Family 184 0.62 26 Family 167 0.57 56 Family 2 0.6 86 Family 208 0.62 27 Family 175 0.57 57 Family 7 0.6 87 Family 19 0.63 28 Family 215 0.57 58 Family 17 0.6 88 Family 37 0.63 29 Family 31 0.58 59 Family 23 0.6 89 Family 116 0.63 30 Family 33 0.58 60 Family 34 0.6 90 Family 142 0.63

[0061] Table 1 shows the 112 families with the highest hypoxia tolerance and the semi-lethal dissolved oxygen values among 220 families. Among them, families 18, 29, 72, 97, 148, 169, 170, and 204 are the most hypoxia-tolerant, and the semi-lethal dissolved oxygen value is 0.55 mg / L.

[0062] (3.2) Screening at the 1-year-old fingerling stage

[0063] The 1-year-old fish fries are fish fries at 12 months old. On June 27, 2022, first aerate the water body in the culture barrel 1 of the low-oxygen stress device until the dissolved oxygen in the water body remains at 5 mg / L. Separate the male and female fish among the 1-year-old fish fries of the 112 full-sib families screened in step (3.1), and then select the individuals in the first 50% of the female fish size and the individuals in the first 50% of the male fish size in each full-sib family, and transfer them together into the culture barrel 1 of the low-oxygen stress device. Operate according to the preset oxygen reduction stress conditions in step (2) to reduce the dissolved oxygen in the water body until 50% of the individuals die. Record the semi-lethal dissolved oxygen, end the stress, restore the normal dissolved oxygen level, fish out the dead individuals, and transfer the surviving individuals back to the nursery pond for continued cultivation. Sort the 112 full-sib families in ascending order of semi-lethal dissolved oxygen, and select 60 full-sib families with the lowest semi-lethal dissolved oxygen level, and continue to cultivate them separately until they reach 2-year-old fish fries.

[0064] Table 2 The first 50% of the families of 1-year-old fish fries with low-oxygen tolerance (60 families)

[0065] Serial number Number Semi-lethal dissolved oxygen level (mg / L) Serial number Number Semi-lethal dissolved oxygen level (mg / L) Serial number Number Semi-lethal dissolved oxygen level (mg / L) Serial number Number Semi-lethal dissolved oxygen level (mg / L) 1 Family 103 0.3 16 Family 143 0.32 31 Family 135 0.36 46 Family 30 0.42 2 Family 102 0.3 17 Family 199 0.32 32 Family 106 0.37 47 Family 5 0.42 3 Family 175 0.3 18 Family 32 0.33 33 Family 34 0.37 48 Family 91 0.43 4 Family 178 0.3 19 Family 66 0.34 34 Family 146 0.37 49 Family 111 0.43 5 Family 95 0.3 20 Family 164 0.34 35 Family 218 0.37 50 Family 33 0.43 6 Family 149 0.3 21 Family 93 0.34 36 Family 212 0.38 51 Family 188 0.43 7 Family 148 0.31 22 Family 200 0.35 37 Family 132 0.38 52 Family 97 0.44 8 Family 6 0.31 23 Family 115 0.35 38 Family 167 0.39 53 Family 81 0.44 9 Family 38 0.31 24 Family 131 0.35 39 Family 84 0.39 54 Family 2 0.44 10 Family 61 0.31 25 Family 53 0.35 40 Family 138 0.4 55 Family 152 0.44 11 Family 196 0.31 26 Family 170 0.36 41 Family 187 0.4 56 Family 123 0.44 12 Family 51 0.32 27 Family 69 0.36 42 Family 147 0.4 57 Family 184 0.44 13 Family 54 0.32 28 Family 7 0.36 43 Family 72 0.41 58 Family 173 0.44 14 Family 82 0.32 29 Family 55 0.36 44 Family 19 0.41 59 Family 103 0.44 15 Family 112 0.32 30 Family 78 0.36 45 Family 109 0.42 60 Family 102 0.44

[0066] Table 2 shows the 60 families with the highest low-oxygen tolerance and the semi-lethal dissolved oxygen values among the 112 families. Among them, families 103, 102, 175, 178, 95, and 149 have the highest low-oxygen tolerance, and the semi-lethal dissolved oxygen value is 0.3 mg / L.

[0067] (3.3)Screening at the 2-year-old fish fry stage

[0068] The 2-year-old fish fries are fish fries at 24 months old. On June 16, 2023, first aerate the water body in the culture barrel 1 of the low-oxygen stress device until the dissolved oxygen in the water body remains at 5 mg / L. Separate the male and female fish among the 2-year-old fish fries of the 60 full-sib families screened in step (3.2), and then select the individuals in the first 50% of the female fish size and the individuals in the first 50% of the male fish size in each full-sib family, and transfer them together into the culture barrel 1 of the low-oxygen stress device. Operate according to the preset oxygen reduction stress conditions in step (2) to reduce the dissolved oxygen in the water body until 50% of the individuals die. Record the semi-lethal dissolved oxygen, end the stress, restore the normal dissolved oxygen level, fish out the dead individuals, and transfer the surviving individuals back to the cultivation pond for continued cultivation. Sort the 60 full-sib families in ascending order of semi-lethal dissolved oxygen, and select the first 25% of the full-sib families with the lowest semi-lethal dissolved oxygen level, a total of 15 full-sib families, and cultivate them separately until they reach 3-year-old fish. See Figure 3 , the morphological changes of the gill tissue of Pelteobagrus vachelli when the dissolved oxygen in the water body is reduced to 2 mg / L.

[0069] ;

[0070] Table 3 shows the 15 most hypoxia-tolerant families among 60 families and their semi-lethal dissolved oxygen values. Among them, families 131, 187, and 123 are the most hypoxia-tolerant, with a semi-lethal dissolved oxygen value of 0.29 mg / L.

[0071] (3.4)Screening at the stage of 3-year-old fish

[0072] Three-year-old fish are 36-month-old fish. On June 10, 2024, the gonads of the fish were well matured at this time and could be used as broodstock to breed offspring. Before being used as breeding parents, hypoxia stress screening was also carried out, that is, the female and male fish with specifications in the top 50% among the female and male fish of 15 full-sib families were selected. The female and male fish of the same full-sib family were placed together in culture barrel 1 of the hypoxia stress device, and the dissolved oxygen in the water body was reduced according to the preset hypoxia stress conditions in step (2) until 50% of the fish died. Record the semi-lethal dissolved oxygen content, end the stress, restore the normal dissolved oxygen level, fish out the dead individuals, and transfer the surviving individuals back to the culture pond for continued cultivation. The Pelteobagrus vachelli of 15 full-sib families with hypoxia tolerance were cultivated as breeding parents to carry out paired breeding among different families. The offspring obtained were stronger in hypoxia tolerance ability than the previous generation and had better growth performance.

[0073] ;

[0074] Table 4 shows the 15 families and their semi-lethal dissolved oxygen values. Among them, family 111 is the most hypoxia-tolerant, with a semi-lethal dissolved oxygen value of 0.25 mg / L.

[0075] Figure 3 Figure legend: (A) Tunel staining results of the gill tissue of Pelteobagrus vachelli under normoxia (5 mg / L) and hypoxia (2 mg / L) stress for 12 h. Yellow arrows indicate apoptotic cells, green boxes indicate interlamellar cell masses (ILCM) between gill lamellae, and red lines indicate the length of the gill lamellae extending out. Scale bar: 20 µm. (B) shows the measurement and analysis results of the ILCM area between the normoxia and hypoxia stress groups in A. (C) shows the measurement and analysis results of the length of the gill lamellae (Lamella) between the normoxia and hypoxia stress groups in A. Using the T-test, p < 0.05 indicates significant difference.

[0076] See Figure 3 On the left side of A in , the Tunel staining results of the gill tissue of Pelteobagrus vachelli under normoxia (5 mg / L) show that the morphology of the gill is basically normal, and no apoptotic signals are found in the gill tissue cells; See Figure 3In the right figure of A, the Tunel staining results of the gill tissues of Pelteobagrus vachelli under hypoxia (2 mg / L) stress for 12 h. Some cells in the gill tissues showed yellowish brown, indicating that gill cells were damaged and apoptosis occurred. At the same time, compared with the control group, the gill lamellae elongated and the area of the cell mass between the gill lamellae decreased significantly. The yellow arrows indicate apoptotic cells, the green boxes indicate the interlamellar cell mass (ILCM) between the gill lamellae, and the red lines indicate the length of the gill lamellae extending out. Scale bar: 20 µm.

[0077] See Figure 3 B in Figure 3 shows the measurement and analysis results of the ILCM area between the normoxia and hypoxia stress groups in A of

[0078] The area of the interlamellar cell mass (ILCM) between the gill lamellae was measured and analyzed using ImageJ software. The results showed that the area of the ILCM decreased significantly after hypoxia stress compared with the control group.

[0079] See Figure 3 C in Figure 3 shows the measurement and analysis results of the length of the gill lamellae between the normoxia and hypoxia stress groups in A of

[0080] The length of the gill lamellae extending out was measured and analyzed using ImageJ software. The results showed that the length of the gill lamellae increased significantly under hypoxia stress.

Claims

1. A method for selecting fast-growing Pelteobagrus vachelli resistant to low oxygen, including a low oxygen stress screening device with a culture barrel (1), characterized in that, The seed selection operation steps are as follows: (1) Establish at least 200 full-sib families of Pelteobagrus vachelli (1.1) Select more than 200 female and male Pelteobagrus vachelli with well-developed gonads from the original and improved seed farms of aquatic products or natural waters such as rivers and lakes as breeding parents. The specification of male fish is not less than 400g, and the specification of female fish is not less than 200g; (1.2) Carry out one-male-one-female paired breeding. The offspring produced are a full-sib family. A total of more than 200 full-sib families are established. Each full-sib family is cultivated separately without mixing with other families; (2) Preset the hypoxia stress conditions (2.1) First, aerate the water in the culture barrel (1) of the hypoxia stress screening device until the dissolved oxygen in the water body remains at 5mg / L or above; (2.2) Reduce the dissolved oxygen in the water body by 0.5mg / L every 2 hours; (2.3) Observe the activities of the fish in real time, record the asphyxia death time, quantity and the dissolved oxygen at that time of the fish until 50% of the fish die of asphyxia, and record the semi-lethal dissolved oxygen value at this time; (3) For more than 200 families, conduct hypoxia stress screening at the summer fingerling stage, 1-year-old fingerling stage, 2-year-old fingerling stage, and 3-year-old fish stage respectively. Select the hypoxia-tolerant individuals, cultivate the hypoxia-tolerant individuals in the next stage, and at the same time eliminate the hypoxia-intolerant individuals; (3.1) Screening at the summer fingerling stage The summer fingerlings are the fry about one month after hatching. Transfer all the fry of the same full-sib family into the hypoxia stress device, reduce the dissolved oxygen in the water body according to step (2) until 50% of the fry die, record the semi-lethal dissolved oxygen value at this time, end the stress, restore the normal dissolved oxygen level, and fish out the dead individuals; Sort more than 200 full-sib families in ascending order of the semi-lethal dissolved oxygen value, and select the top 50% of the most hypoxia-tolerant families to continue cultivating alone until they reach 1-year-old fingerlings; (3.2) Screening at the 1-year-old fingerling stage Select the female and male fish in the top 50% of the specifications in each full-sib family respectively, and then transfer them into the hypoxia stress device together for screening according to step (2); Sort more than 200 full-sib families in ascending order of the semi-lethal dissolved oxygen value, and select the top 50% of the most hypoxia-tolerant families to continue cultivating alone until they reach 2-year-old fingerlings; (3.3) Screening at the 2-year-old fingerling stage Select the female and male fish in the top 50% of the specifications in each full-sib family respectively, and then transfer them into the hypoxia stress device together for screening according to step (2); Sort more than 200 full-sib families in ascending order of the semi-lethal dissolved oxygen value, and select the top 25% of the most hypoxia-tolerant families to continue cultivating alone until they reach 3-year-old fish; (3.4) Screening at the 3-year-old fish stage Select the female and male fish in the top 50% of the specifications in each full-sib family respectively, and then transfer them into the hypoxia stress device together for screening according to step (2), and obtain the selected full-sib families as breeding parents for cultivation; Carry out paired breeding among the selected full-sib families. The offspring are stronger in hypoxia tolerance and better in growth performance than the previous generation.

2. The method for selecting Pseudobagrus vachelli with fast growth and hypoxia tolerance according to claim 1, wherein: In step (2.2), the specific operation of reducing the dissolved oxygen content in the water body by 0.5 mg / L every 2 hours: turn down the valve of the oxygen cylinder, turn up the valve of the nitrogen cylinder, and observe the change of the value measured by the dissolved oxygen meter until the dissolved oxygen value is stable.

3. The method for selecting Pseudobagrus vachelli with fast growth under low oxygen tolerance according to claim 1, wherein: In step (3.2), the 1-year-old fish species are fish species at 12 months old. Separate the female and male fish in each full-sib family of 1-year-old fish species for temporary cultivation. Select the individuals with the first 50% of the female fish specifications and the individuals with the first 50% of the male fish specifications in each full-sib family, and then place the selected female and male fish together in the hypoxia stress device. Reduce the dissolved oxygen content in the water body according to step (2) until 50% of the individuals die. Record the semi-lethal dissolved oxygen value, end the stress, restore the normal dissolved oxygen level, and fish out the dead individuals; sort them in ascending order of the semi-lethal dissolved oxygen value, and select the first 50% of the families with the highest hypoxia tolerance to continue to be cultivated separately until they reach 2-year-old fish species.

4. The method for selecting Pseudobagrus vachelli with low oxygen tolerance and fast growth according to claim 1, characterized in that: In step (3.3), the 2-year-old fish species are fish species at 24 months old. Select the individuals with the first 50% of the female fish specifications and the individuals with the first 50% of the male fish specifications in each full-sib family of 2-year-old fish species, and then place the selected female and male fish together in the hypoxia stress device. Reduce the dissolved oxygen content in the water body according to step (2) until 50% of the individuals die. Record the semi-lethal dissolved oxygen value, end the stress, restore the normal dissolved oxygen level, and fish out the dead individuals; sort them in ascending order of the semi-lethal dissolved oxygen value, and select the first 25% of the families with the highest hypoxia tolerance to continue to be cultivated separately until they reach 3-year-old fish.

5. The method for selecting Pseudobagrus vachelli with fast growth and hypoxia tolerance according to claim 1, characterized in that: In step (3.4), the 3-year-old fish species are fish at 36 months old. At this time, the fish are in good sexual maturity and can be used as broodstock to reproduce offspring; before being used as breeding parents, they are also screened by hypoxia stress. Select the individuals with the first 50% of the female fish specifications and the individuals with the first 50% of the male fish specifications in each full-sib family of 3-year-old fish species respectively, and then place the selected female and male fish together in the hypoxia stress device. Reduce the dissolved oxygen content in the water body according to step (2) until 50% of the fish species die. Record the semi-lethal dissolved oxygen value, end the stress, restore the normal dissolved oxygen level, and fish out the dead individuals; cultivate the hypoxia-tolerant Pelteobagrus vachelli as breeding parents.

6. A hypoxia stress screening device for the selection of Pelteobagrus vachelli, characterized in that: It includes a culture barrel (1). An aeration disk (2) is arranged at the inner bottom of the culture barrel (1). The aeration disk (2) is connected through a hose to an oxygen cylinder (3) and a nitrogen cylinder (4) connected in parallel; a mesh grille (5) is arranged at the upper part inside the culture barrel (1). The mesh size of the mesh grille (5) is smaller than the head width of the fish species to be put in, preventing the fish head from floating out of the water surface. When water is filled into the culture barrel (1), the mesh grille (5) is at the liquid level, and a dissolved oxygen measuring probe (6) is arranged in the water body.

7. The hypoxia stress screening device for the selection of Pelteobagrus vachelli according to claim 6, characterized in that: The diameter of the culture barrel (1) is 0.6 m and the height is 1.0 m.

8. A hypoxia stress screening device for selecting Pseudobagrus vachelli according to claim 6, characterized in that: The aeration disk (2) is a circular ceramic aeration disk.

9. The hypoxia stress screening device for selecting Pseudobagrus vachelli according to claim 6, wherein: The volumes of the oxygen cylinder (3) and the nitrogen cylinder (4) are both 40 L.

Images