Method for breeding new germplasm of eriocheir sinensis in cold region with large size

Abstract

The application discloses a method for breeding a new germplasm of Eriocheir sinensis in cold regions, and belongs to the technical field of aquaculture. The method comprises the following steps: screening of two-year-old immature Eriocheir sinensis; overwintering of the two-year-old immature Eriocheir sinensis; water body disinfection, overwintering density, feed feeding and water body indexes; breeding of three-year-old large-size Eriocheir sinensis: breeding pond and aquatic plant planting; seedling release; management during the breeding period; and the three-year-old Eriocheir sinensis is sold as a commodity crab when the size and gonadal development meet the requirements. In the application, a new Eriocheir sinensis germplasm, i.e., three-year-old Eriocheir sinensis, is bred, and the size of the Eriocheir sinensis bred in cold regions is improved. In the application, the average size of the female three-year-old Eriocheir sinensis bred from two-year-old immature Eriocheir sinensis is (96.82+2.48) g, and the average size of the male three-year-old Eriocheir sinensis is (135.91+4.20) g. Compared with the two-year-old mature Eriocheir sinensis bred by using the prior art, the size is significantly increased, and the purpose of breeding large-size Eriocheir sinensis is achieved.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology; specifically, it relates to a new germplasm breeding method for large-sized Chinese mitten crabs in cold regions. Background Technology

[0002] The Chinese mitten crab (Eriocheir sinensis) belongs to the phylum Arthropoda, class Crustacea, order Decapoda, and family Eriocheiridae. It is a native crab species of East Asia with significant economic value, and its wild populations are mainly distributed in rivers and lakes connected to the sea along the eastern coast of my country. As of January 2024, my country had artificially bred five new varieties of Chinese mitten crabs from the Yangtze River system: "Yangtze No. 1," "Yangtze No. 2," "Jianghai 21," "Noah No. 1," and "Jinong No. 1," and one new variety from the Liaohe River system, "Guanghe No. 1." The breeding areas for these varieties differ somewhat. The Yangtze River system varieties are mainly bred in the Yangtze River basin, such as Jiangsu, Jiangxi, Anhui, and Hubei provinces; while the Liaohe River system variety "Guanghe No. 1" is mainly bred in parts of Northeast and North China, such as Heilongjiang, Jilin, Liaoning, and Tianjin. Currently, Chinese mitten crabs farmed in cold-region ponds and rice paddies have shorter growth periods and fewer molts, resulting in smaller sizes and lower quality. Wang Shihui et al. (2021) found that the average size of female Chinese mitten crabs cultured in paddy fields in cold regions of the Liaohe River system is about 60g, and that of males is about 90g. The average size of females cultured in ponds is slightly higher, with females at about 70g and males at about 100g. However, compared with the large-sized Chinese mitten crabs required by the market, the current size of cultured Chinese mitten crabs is still relatively small.

[0003] Currently, from an economic perspective, the size of Chinese mitten crabs is significantly positively correlated with market price. However, under current farming practices, Chinese mitten crabs in northern regions are marketed after reaching two years of age. Even if they are farmed for another year, the high sexual maturity of the crab population (over 90% of the total number) prevents them from growing further and exceeding their current size. Therefore, improving the size of Chinese mitten crabs raised in cold regions is a crucial measure to overcome the bottleneck in the development of the northern Chinese mitten crab industry. While genetic breeding can improve the size of Chinese mitten crabs, it requires significant investment in breeding and farming facilities and equipment, resulting in substantial upfront costs and a long breeding cycle with relatively slow results. Therefore, rapidly improving the size of Chinese mitten crabs through farming methods is a key area for breakthrough. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems existing in the prior art, and to propose a new germplasm farming method for large-sized Chinese mitten crabs in cold regions.

[0005] A new breeding method for large-sized Chinese mitten crabs in cold regions is implemented through the following steps:

[0006] Screening of immature Chinese mitten crabs in their first and second years:

[0007] At the end of September, individuals with intact limbs, strong activity, and who were not yet sexually mature were selected from two-year-old Chinese mitten crabs cultured in cold-region ponds.

[0008] II. Overwintering of two-year-old immature Chinese mitten crabs:

[0009] Water disinfection, overwintering density regulation, feed feeding, and water quality indicators;

[0010] III. Farming of large-sized, three-year-old Chinese mitten crabs:

[0011] ① Aquaculture pond and aquatic plant planting: In the following spring, prepare an outdoor aquaculture pond with a central platform. The aquaculture pond is surrounded by a 30-40cm high escape-proof net, with the bottom of the net buried 20cm in the soil. In early April, disinfect the aquaculture pond. Two weeks later, plant Elodea on the central platform of the aquaculture pond and isolate it with a net. After the Elodea has taken root and grown vigorously, remove the net.

[0012] ② Seedling stocking: In late April, select two-year-old, sexually immature Chinese mitten crabs with intact limbs and strong activity after overwintering, and place them in the above-mentioned breeding ponds at a stocking density of 800-1000 individuals / mu, with a water depth of 0.8-1m.

[0013] ③ Management during the breeding period: Throughout the breeding process, the physicochemical indicators of the pond water should be maintained, with ammonia nitrogen content less than 1 mg / L and pH controlled between 7.0 and 8.5. When the water temperature is below 12℃, feed with formulated feed once every three days; when the water temperature is above 12℃, feed with formulated feed once a day. In the early stage of breeding, feed with formulated feed containing 38% to 42% protein; in the middle stage of breeding, feed with formulated feed containing 34% to 38% protein; and in the later stage of breeding, feed with formulated feed containing 38% to 42% protein.

[0014] IV. Size and Gonadal Development: From September to October, three-year-old Chinese mitten crabs that meet the size and gonadal development requirements will be sold as commercial crabs.

[0015] The specifications and standards for gonadal development are as follows: female three-year-old Chinese mitten crabs weigh ≥70g and have a gonadal index of ≥3%; male three-year-old Chinese mitten crabs weigh ≥100g and have a gonadal index of ≥1.5%.

[0016] Furthermore, the criteria for determining sexually immature individuals mentioned in step one are as follows:

[0017] The criterion for determining immature females is that the ratio of the width of the third segment from the navel to the width of the left and right thoracic segments is less than 1.

[0018] b. Criteria for identifying immature males: The ventral villi of the cheliped phalanges are not fused with the dorsal villi, or the villi of the cheliped phalanges are short and sparse;

[0019] The width of the left and right thoracic segments refers to the junction between the second and third walking legs.

[0020] Furthermore, regarding the water disinfection mentioned in step two: before releasing the selected two-year-old immature Chinese mitten crabs, the overwintering pond needs to be disinfected, and the dosage of bleaching powder used is 15 kg / mu.

[0021] Furthermore, the overwintering density mentioned in step two is as follows: the selected two-year-old immature Chinese mitten crabs are released into the overwintering pond at an overwintering density of 400-500 kg / mu.

[0022] Furthermore, regarding the feeding described in step two: before freezing, when the water temperature is between 12 and 15°C, feed the compound feed once a day in the afternoon; when the water temperature drops below 12°C, feed twice a week until freezing.

[0023] Furthermore, regarding the water quality indicators mentioned in step two: During the wintering period, pay attention to clearing snow to ensure the water's light transmittance. At the same time, regularly test the water's physicochemical indicators. The dissolved oxygen in the water should be greater than 4 mg / L, the ammonia nitrogen content should be less than 1 mg / L, the pH should be controlled between 7.0 and 8.5, and the water depth should be maintained above 2.5 m before the ice freezes.

[0024] Furthermore, in step three①, the disinfection treatment involves spreading 75 kg / mu of quicklime; the spacing between plants of Elodea is 1 m, and the row spacing is 2 m.

[0025] Furthermore, before releasing the seedlings as described in step 3②, the water in the aquaculture pond should be treated with fermented chicken manure.

[0026] Furthermore, in step 3③, the early stage of aquaculture refers to early May to late June; the middle stage of aquaculture refers to early July to mid-August; and the late stage of aquaculture refers to late August to late September.

[0027] Furthermore, in step 3③, the management during the breeding period includes patrolling the pond once in the morning and once in the evening to observe the feeding, activity and molting of the Chinese mitten crabs, checking the breeding pond facilities, and repairing any damaged escape-proof nets in a timely manner.

[0028] This invention has led to the cultivation of a new breed of Chinese mitten crab, namely a three-year-old Chinese mitten crab, which improves the size of Chinese mitten crabs raised in cold regions and provides an important direction for the development of the Chinese mitten crab industry in cold regions.

[0029] In this invention, the average size of female three-year-old Chinese mitten crabs raised from two-year-old immature crabs was (96.82±2.48)g, and that of males was (135.91±4.20)g. Compared with two-year-old mature Chinese mitten crabs raised by existing methods, the size of these crabs was significantly higher (P<0.05), thus achieving the goal of raising large-sized Chinese mitten crabs.

[0030] This invention is applicable to the cultivation of new germplasm of large-sized Chinese mitten crabs in cold regions. Detailed Implementation

[0031] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0032] Specific Implementation Method 1: This implementation method is a new germplasm farming method for large-sized Chinese mitten crabs in cold regions, which is carried out according to the following steps:

[0033] Screening of immature Chinese mitten crabs in their first and second years:

[0034] At the end of September, individuals with intact limbs, strong activity, and who were not yet sexually mature were selected from two-year-old Chinese mitten crabs cultured in cold-region ponds.

[0035] II. Overwintering of two-year-old immature Chinese mitten crabs:

[0036] Water disinfection, overwintering density regulation, feed feeding, and water quality indicators;

[0037] III. Farming of large-sized, three-year-old Chinese mitten crabs:

[0038] ① Aquaculture pond and aquatic plant planting: In the following spring, prepare an outdoor aquaculture pond with a central platform. The aquaculture pond is surrounded by a 30-40cm high escape-proof net, with the bottom of the escape-proof net buried 20cm in the soil. In early April, disinfect the aquaculture pond. Two weeks later, plant Elodea on the central platform of the aquaculture pond and isolate it with a net. Two weeks later, remove the net.

[0039] ② Seedling stocking: In late April, select two-year-old, sexually immature Chinese mitten crabs with intact limbs and strong activity after overwintering, and place them in the above-mentioned breeding ponds at a stocking density of 800-1000 individuals / mu, with a water depth of 0.8-1m.

[0040] ③ Management during the breeding period: Throughout the breeding process, the physicochemical indicators of the pond water should be maintained, with ammonia nitrogen content less than 1 mg / L and pH controlled between 7.0 and 8.5. When the water temperature is below 12℃, feed with formulated feed once every three days; when the water temperature is above 12℃, feed with formulated feed once a day. In the early stage of breeding, feed with formulated feed containing 38% to 42% protein; in the middle stage of breeding, feed with formulated feed containing 34% to 38% protein; and in the later stage of breeding, feed with formulated feed containing 38% to 42% protein.

[0041] IV. Size and Gonadal Development: From September to October, three-year-old Chinese mitten crabs that meet the size and gonadal development requirements will be sold as commercial crabs.

[0042] The specifications and standards for gonadal development are as follows: female three-year-old Chinese mitten crabs weigh ≥70g and have a gonadal index of ≥3%; male three-year-old Chinese mitten crabs weigh ≥100g and have a gonadal index of ≥1.5%.

[0043] The aquaculture pond with a central platform described in step three① of this embodiment has no fixed requirements in terms of shape and size.

[0044] The Elodea described in step three① of this embodiment can provide a hiding place for the Chinese mitten crab to molt, and it is also an important plant-based food source and can purify water.

[0045] The compound feeds described in this embodiment are all commercially available high-protein, high-fat compound feeds suitable for crab farming.

[0046] The diameter and feeding amount of the compound feed described in this embodiment are adjusted appropriately according to the size of the Chinese mitten crab.

[0047] In this embodiment, the Chinese mitten crab is fed a compound feed with a protein content of 38% to 42% in the early stage of breeding to facilitate its rapid recovery; in the later stage of breeding, it is fed a compound feed with a protein content of 38% to 42% to facilitate its fattening.

[0048] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the criteria for determining sexually immature individuals in step one are as follows:

[0049] The criterion for determining immature females is that the ratio of the width of the third segment from the navel to the width of the left and right thoracic segments is less than 1.

[0050] b. Criteria for identifying immature males: The ventral villi of the cheliped phalanges are not fused with the dorsal villi, or the villi of the cheliped phalanges are short and sparse;

[0051] The width of the left and right thoracic segments refers to the junction between the second and third walking legs. Other steps and parameters are the same as in Specific Implementation Method 1.

[0052] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the water disinfection mentioned in step two involves disinfecting the overwintering pond before releasing the selected two-year-old immature Chinese mitten crabs. The dosage of bleaching powder used is 15 kg / mu. Other steps and parameters are the same as in Specific Implementation Method One.

[0053] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that the overwintering density mentioned in step two is: the selected two-year-old immature Chinese mitten crabs are released into the overwintering pond at a density of 400-500 kg / mu. Other steps and parameters are the same as in Specific Implementation Method One.

[0054] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method One in that, in step two, the feed feeding is as follows: before freezing, when the water temperature is between 12 and 15°C, feed the formulated feed once a day in the afternoon; when the water temperature drops below 12°C, the feeding frequency is twice a week until freezing. Other steps and parameters are the same as in Specific Implementation Method One.

[0055] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method One in that the water quality indicators mentioned in step two are as follows: During the wintering period, pay attention to clearing snow to ensure water transparency. At the same time, regularly test the physicochemical indicators of the water. Dissolved oxygen should be greater than 4 mg / L, ammonia nitrogen content should be less than 1 mg / L, pH should be controlled between 7.0 and 8.5, and the water depth should be maintained above 2.5 m before ice formation. Other steps and parameters are the same as in Specific Implementation Method One.

[0056] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method One in that, in step three①, the disinfection treatment involves spreading 75 kg / mu of quicklime; the spacing between plants of *Elodea nuttallii* is 1 m, and the row spacing is 2 m. Other steps and parameters are the same as in Specific Implementation Method One.

[0057] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method One in that, before releasing the seedlings in step three ②, the water in the aquaculture pond must be treated with fermented chicken manure. Other steps and parameters are the same as in Specific Implementation Method One.

[0058] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method One in that the early stage of aquaculture mentioned in step three ③ refers to early May to late June; the middle stage of aquaculture refers to early July to mid-August; and the late stage of aquaculture refers to late August to late September. Other steps and parameters are the same as in Specific Implementation Method One.

[0059] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method One in that, during the aquaculture period, as described in step three ③, the pond should be inspected twice daily, morning and evening, to observe the feeding, activity, and molting of the Chinese mitten crabs, check the pond facilities, and promptly repair any damaged escape-prevention nets. Other steps and parameters are the same as in Specific Implementation Method One.

[0060] The beneficial effects of the present invention are verified through the following embodiments:

[0061] Example:

[0062] A new breeding method for large-sized Chinese mitten crabs in cold regions is implemented through the following steps:

[0063] Screening of immature Chinese mitten crabs in their first and second years:

[0064] At the end of September, individuals with intact limbs, strong activity, and who were not yet sexually mature were selected from two-year-old Chinese mitten crabs cultured in cold-region ponds.

[0065] II. Overwintering of two-year-old immature Chinese mitten crabs:

[0066] Water disinfection, overwintering density regulation, feed feeding, and water quality indicators;

[0067] III. Farming of large-sized, three-year-old Chinese mitten crabs:

[0068] ① Aquaculture pond and aquatic plant planting: In the following spring, prepare an outdoor aquaculture pond with a central platform. The pond is surrounded by a 30-40cm high escape-proof net, with the bottom of the net buried 20cm in the soil. In early April, disinfect the aquaculture pond. Two weeks later, plant Elodea nuttallii on the central platform of the aquaculture pond and isolate it with a net. Remove the net after the Elodea nuttallii has taken root and grown vigorously.

[0069] ② Seedling stocking: In late April, select two-year-old, sexually immature Chinese mitten crabs with intact limbs and strong activity after overwintering, and place them in the above-mentioned breeding ponds at a stocking density of 800-1000 individuals / mu, with a water depth of 0.8-1m.

[0070] ③ Management during the breeding period: Throughout the breeding process, the physicochemical indicators of the pond water should be maintained, with ammonia nitrogen content less than 1 mg / L and pH controlled between 7.0 and 8.5. When the water temperature is below 12℃, feed with formulated feed once every three days; when the water temperature is above 12℃, feed with formulated feed once a day. In the early stage of breeding, feed with formulated feed containing 38% to 42% protein; in the middle stage of breeding, feed with formulated feed containing 34% to 38% protein; and in the later stage of breeding, feed with formulated feed containing 38% to 42% protein.

[0071] IV. Size and Gonadal Development: From September to October, three-year-old Chinese mitten crabs that meet the size and gonadal development requirements will be sold as commercial crabs.

[0072] The specifications and standards for gonadal development are as follows: female three-year-old Chinese mitten crabs weigh ≥70g and have a gonadal index of ≥3%; male three-year-old Chinese mitten crabs weigh ≥100g and have a gonadal index of ≥1.5%.

[0073] The criteria for determining sexually immature individuals in step one of this embodiment are as follows:

[0074] The criterion for determining immature females is that the ratio of the width of the third segment from the navel to the width of the left and right thoracic segments is less than 1.

[0075] b. Criteria for identifying immature males: The ventral villi of the cheliped phalanges are not fused with the dorsal villi, or the villi of the cheliped phalanges are short and sparse;

[0076] The width of the left and right thoracic segments refers to the junction between the second and third walking legs.

[0077] In step two of this embodiment, water disinfection is required: before releasing the selected two-year-old immature Chinese mitten crabs, the overwintering pond needs to be disinfected, and the dosage of bleaching powder used is 15 kg / mu.

[0078] The overwintering density mentioned in step two of this embodiment is as follows: the selected two-year-old immature Chinese mitten crabs are released into the overwintering pond at an overwintering density of 400-500 kg / mu.

[0079] In step two of this embodiment, the feed feeding is as follows: before freezing, when the water temperature is between 12 and 15°C, feed the compound feed once a day in the afternoon; when the water temperature drops below 12°C, feed the feed twice a week until freezing.

[0080] The water quality indicators mentioned in step two of this embodiment are as follows: During the wintering period, pay attention to clearing snow to ensure the water's light transmittance. At the same time, regularly test the water's physicochemical indicators. The dissolved oxygen in the water should be greater than 4 mg / L, the ammonia nitrogen content should be less than 1 mg / L, the pH should be controlled between 7.0 and 8.5, and the water depth should be maintained above 2.5m before the ice freezes.

[0081] In step 3① of this embodiment, the disinfection treatment involves spreading 75 kg / mu of quicklime; the spacing between plants of Elodea is 1 m and the row spacing is 2 m.

[0082] Before releasing the seedlings as described in step 3② of this embodiment, the water in the aquaculture pond should be treated with fermented chicken manure.

[0083] In step 3③ of this embodiment, the early stage of aquaculture refers to early May to late June; the middle stage of aquaculture refers to early July to mid-August; and the late stage of aquaculture refers to late August to late September.

[0084] In step 3③ of this embodiment, the management during the breeding period includes patrolling the pond once in the morning and once in the evening to observe the feeding, activity and molting of the Chinese mitten crabs, checking the breeding pond facilities, and repairing any damaged escape-proof nets in a timely manner.

[0085] The aquaculture method described in this implementation was used in the experiment: In September 2020, the applicant selected two-year-old immature Chinese mitten crabs (approximately 10% of the total number of crabs) at a fishery aquaculture cooperative in Zhaodong City, Suihua City, Heilongjiang Province. Visual observation and dissection confirmed that these crabs were all two-year-old immature Chinese mitten crabs. They were overwintered according to the method described in this implementation. The following spring, a total of 2600 two-year-old immature Chinese mitten crabs (average size 44.42g) were released into an outdoor pond for aquaculture. Normal one-year-old juvenile crabs were used as a control group, with an average size of 8.03g. Following the methods described in this implementation, in September 2021, a weight comparison showed that the average size of normal two-year-old mature Chinese mitten crabs was (71.87±4.11) g for females and (90.09±1.43) g for males. However, the average size of three-year-old Chinese mitten crabs raised from two-year-old immature crabs was (96.82±2.48) g for females and (135.91±4.20) g for males. There was a significant difference in size between both two-year-old and three-year-old crabs, regardless of gender, with the three-year-old crabs being significantly larger than the two-year-old crabs (P<0.05). These results indicate that by raising two-year-old immature Chinese mitten crabs for an additional year using the methods described in this implementation, it is possible to achieve the goal of raising large-sized Chinese mitten crabs.

Claims

1. A new method for breeding large-sized Chinese mitten crabs in cold regions, characterized by... It is implemented in the following steps: Screening of immature Chinese mitten crabs in their first and second years: At the end of September, individuals with intact limbs, strong activity, and who were not yet sexually mature were selected from two-year-old Chinese mitten crabs cultured in cold-region ponds. II. Overwintering of two-year-old immature Chinese mitten crabs: Water disinfection, overwintering density regulation, feed feeding, and water quality indicators; III. Farming of large-sized, three-year-old Chinese mitten crabs: ① Aquaculture pond and aquatic plant planting: In the following spring, prepare an outdoor aquaculture pond with a central platform. The aquaculture pond is surrounded by a 30-40cm high escape-proof net, with the bottom of the net buried 20cm in the soil. In early April, disinfect the aquaculture pond. Two weeks later, plant Elodea nuttallii on the central platform of the aquaculture pond and isolate it with a net. After the Elodea nuttallii has taken root and grown vigorously, remove the net. ② Seedling stocking: In late April, select two-year-old, immature Chinese mitten crabs with intact limbs and strong activity after overwintering, and place them in the above-mentioned breeding ponds at a stocking density of 800-1000 individuals / acre, with a water depth of 0.8-1m. ③ Management during the breeding period: Throughout the breeding process, the physicochemical indicators of the pond water should be maintained, with ammonia nitrogen content less than 1 mg / L and pH controlled between 7.0 and 8.

5. When the water temperature is below 12℃, feed with formulated feed once every three days; when the water temperature is above 12℃, feed with formulated feed once a day. In the early stage of breeding, feed with formulated feed containing 38% to 42% protein; in the middle stage of breeding, feed with formulated feed containing 34% to 38% protein; and in the later stage of breeding, feed with formulated feed containing 38% to 42% protein. IV. Size and Gonadal Development: From September to October, three-year-old Chinese mitten crabs that meet the size and gonadal development requirements will be sold as commercial crabs. The specifications and standards for gonadal development are as follows: female three-year-old Chinese mitten crabs weigh ≥70g and have a gonadal index of ≥3%; male three-year-old Chinese mitten crabs weigh ≥100g and have a gonadal index of ≥1.5%. In step two, the feed feeding is as follows: before freezing, when the water temperature is between 12 and 15°C, feed the compound feed once a day in the afternoon; when the water temperature drops below 12°C, feed twice a week until freezing. The water quality indicators mentioned in step two are as follows: During the wintering period, pay attention to clearing snow and ensuring the light transmittance of the water body. At the same time, regularly test the physicochemical indicators of the water quality. The dissolved oxygen in the water body should be greater than 4 mg / L, the ammonia nitrogen content should be less than 1 mg / L, the pH should be controlled between 7.0 and 8.5, and the water depth should be maintained above 2.5m before the ice freezes. The disinfection treatment described in step 3① involves spreading 75 kg of quicklime per mu; the spacing between plants of Elodea is 1 m and the row spacing is 2 m.

2. The method for cultivating large-sized Chinese mitten crabs in cold regions according to claim 1, characterized in that... The criteria for determining sexually immature individuals mentioned in step one are as follows: The criterion for determining immature females is that the ratio of the width of the third segment from the navel to the width of the left and right thoracic segments is less than 1. b. Criteria for identifying immature males: The ventral villi of the cheliped phalanges are not fused with the dorsal villi, or the villi of the cheliped phalanges are short and sparse; The width of the left and right thoracic segments refers to the junction between the second and third walking legs.

3. The method for cultivating large-sized Chinese mitten crabs in cold regions according to claim 1, characterized in that... Water disinfection as described in step two: Before releasing the selected two-year-old immature Chinese mitten crabs, the overwintering pond needs to be disinfected, and the dosage of bleaching powder used is 15 kg / mu.

4. The method for cultivating large-sized Chinese mitten crabs in cold regions according to claim 1, characterized in that... The overwintering density mentioned in step two: Selected two-year-old immature Chinese mitten crabs are released into the overwintering pond at an overwintering density of 400-500 kg / mu.

5. The method for cultivating large-sized Chinese mitten crabs in cold regions according to claim 1, characterized in that... Before releasing the seedlings as described in step 3②, the water in the aquaculture pond should be treated with fermented chicken manure.

6. The method for cultivating large-sized Chinese mitten crabs in cold regions according to claim 1, characterized in that... The early stage of breeding, as described in step 3③, refers to the period from early May to late June; the middle stage of breeding refers to the period from early July to mid-August; and the late stage of breeding refers to the period from late August to late September.

7. The method for cultivating large-sized Chinese mitten crabs in cold regions according to claim 1, characterized in that... In step 3③, the management during the breeding period includes patrolling the pond once in the morning and once in the evening to observe the feeding, activity and molting of the Chinese mitten crabs, checking the breeding pond facilities and repairing any damaged escape-proof nets in a timely manner.