A staged culture method for cold-region crayfish

Abstract

A staged culture method for cold-region Procambarus clarkii is disclosed. The present invention addresses the low survival rate of existing cold-region Procambarus clarkii seedlings and the problem of obtaining high-quality Procambarus clarkii seedlings. The method comprises the following steps: 1. pond reconstruction, preparation of a simple greenhouse in the deep-water area, and water injection into the deep-water area; 2. construction of an ecological water environment; 3. installation of shrimp nests and sunshade nets; 4. disinfection and stocking of shrimp seedlings; 5. first-stage culture and manual management; 6. preparation of ponds outside the greenhouse; 7. second-stage culture and manual management; 8. pond division; and 9. third-stage culture. The present invention can improve the survival rate of shrimp seedlings, enhance the physical fitness of shrimp seedlings, and obtain uniformly sized seedlings and commercial shrimp at a low cost, making it particularly suitable for the culture and production of cold-region Procambarus clarkii in northern China.

Description

Technical Field

[0001] The invention relates to a staged culture method for Procambarus clarkii in cold regions. Background Art

[0002] Procambarus clarkii, commonly known as freshwater crayfish, belongs to the phylum Arthropoda, class Crustacea, order Decapoda, family Cheraxidae, and genus Procambarus. Its rapid growth and unique flavor have made it a popular delicacy on Chinese tables and a must-have for late-night snacks. In 2021, the total output value of my country's crayfish industry reached 422.195 billion yuan, a year-on-year increase of 22.43%. Of this total, the crayfish farming industry generated 82.344 billion yuan; the secondary industry, primarily processing, generated 36.851 billion yuan; and the tertiary industry, primarily catering, generated 303 billion yuan. The crayfish industry plays a vital role in ensuring a stable supply of essential food and beverages and promoting agricultural efficiency and increased farmers' income.

[0003] Heilongjiang Province is located in the high-altitude and cold zone of northeastern my country. It is rich in water resources, but its fishery farming structure is relatively simple. Aquaculture varieties are mainly local fish, and the number of shrimp farming varieties, farming area and production are extremely small. In recent years, with the booming of Procambarus clarkii, market demand has been increasing, and farming Procambarus clarkii has become one of the main models for the development of ecological circular agriculture. In 2019 and 2020, the Fisheries Branch of the Harbin Academy of Agricultural Sciences in the province began to farm Procambarus clarkii. After nearly two years of long-distance transportation tests and pond farming tests, it was shown that although the survival rate of Procambarus clarkii broodstock and large-sized (over 5 cm) seedlings can reach 75% during long-distance transportation, the survival rate in ponds after transportation to cold areas (within 10 days) is less than 10%, which seriously limits the development of Procambarus clarkii farming in cold areas. From 2021 to 2022, the survival rate of local Procambarus clarkii seedlings, experimentally cultivated by the Cold Region Shrimp Research Center of the Aquatic Products Branch of the Harbin Academy of Agricultural Sciences, reached 70-80%. Ecological pond aquaculture yielded 200 kilograms per mu (approximately 100 catties) and paddy field aquaculture yielded 100 kilograms per mu (approximately 100 kg). However, the aquaculture technology is relatively extensive, and there are no large-scale seedling cultivation bases for Procambarus clarkii. Therefore, expanding the cultivation of local seedlings is a key technology for reducing aquaculture costs and promoting the development of the cold-region Procambarus clarkii industry. Summary of the Invention

[0004] The present invention aims to solve the problems of low survival rate of Procambarus clarkii seedlings in cold regions and obtain high-quality Procambarus clarkii seedlings, and provides a staged culture method for Procambarus clarkii in cold regions.

[0005] A staged culture method for cold-region crayfish is specifically carried out according to the following steps:

[0006] 1. Preliminary preparations:

[0007] ① Pond reconstruction: A deep water area with an area of 1 mu and a depth of 0.5 m was excavated on one side of the original pond, which covers an area of 10 mu and is 2 m deep. A simple greenhouse was built on the deep water area, and the excavated soil was used as a dam for the deep water area. The dam was 1 m high, with a slope ratio of 1:1 and a width of 1 m. An operating area was designated within the greenhouse within the deep water area, connected to the dam of the original pond via a gentle slope.

[0008] ② Preparation of simple greenhouse in deep water area: Before winter, fix a simple sunshade bracket outside the operation area in the greenhouse. The bracket is a steel pipe structure with a height of 2.5m. In mid-March of the following year, install the greenhouse film outside the simple greenhouse.

[0009] ③ Deep water area water injection: Inject groundwater treated by a filtration system or fishery water that meets aquaculture standards into the deep water area to form a fish pond; install aeration equipment in the fish pond, control the water temperature at above 8°C, and seal the injection and discharge outlets with screens;

[0010] 2. Building an ecological water environment:

[0011] Plant aquatic plants that account for 50% of the total volume of the water body in deep water areas, add biological agents to the water to regulate water quality, cultivate natural bait, and build a green ecological aquaculture environment;

[0012] 3. Set up shrimp nests and shade nets:

[0013] Several shrimp nest corrugated boards are placed horizontally in a deep water area to form artificial nests. The shrimp nest corrugated boards are made of PVC and are 1 meter long, 0.3 meters wide, and 3 centimeters high. The shrimp nest corrugated boards are located on the same plane, and adjacent shrimp nests are staggered. Black sunshade nets are placed at the staggered positions, and the black sunshade nets occupy 20% of the area of the deep water area.

[0014] 4. Disinfection and stocking of shrimp fry:

[0015] After slowing down, the shrimp fry are placed in deep water; the stocking density is 300,000 per mu; slowing down the fry: place the plastic bag or basin containing the shrimp fry in water that is the same temperature as the fish pond for 5 to 10 minutes. After the water temperature is balanced, slowly pour the shrimp fry and the water into the fish pond;

[0016] 5. The first stage of breeding and artificial management:

[0017] The shrimp fry are not fed for two days after entering the pond; feeding begins on the third day, and each cycle lasts for seven days. Within each cycle, pellet feed is fed for the first three days, animal bait is fed on the fourth day, pellet feed is fed on the fifth and sixth days, and bio-based bait is fed on the seventh day. The daily feeding amount within a cycle is 3-5% of the shrimp's body weight, and the feeding time is once in the morning and evening, with 30% of the daily feeding amount in the morning and 70% of the daily feeding amount in the evening. The dissolved oxygen content in the water is controlled at above 4mg / L using nano-aerators.

[0018] 6. Preparation of the outdoor pond: When the outdoor minimum temperature reaches 5°C or above, add groundwater to the outdoor pond, plant aquatic plants, place a sunshade net, and prepare low-temperature fertilizer and water. The sunshade net should occupy 30% of the outdoor pond area.

[0019] 7. Second stage of breeding and manual management: When the shrimp fry in the deep water area grow to more than 3cm and the outdoor water temperature is above 12℃, add water to the deep water area and the pond outside the shed to ensure that the temperature difference does not exceed 3℃; this allows the shrimp in the deep water area to climb over the low dam and enter the pond outside the shed for the second stage of breeding; continue manual management;

[0020] 8. Pond division: From May to June, when the shrimp fry grow to 5-8 cm, most of them are gradually caught with ground traps and placed in ponds or rice fields for commercial shrimp farming;

[0021] 9. The third stage of breeding: the remaining shrimp fry continue to be cultured in the pond and continue to be managed manually; in September, the shrimp weight reaches more than 35g, completing the stage-by-stage breeding of cold-region crayfish.

[0022] The beneficial effects of the present invention are:

[0023] The present invention utilizes outdoor pond renovation and the installation of greenhouses in some areas to cultivate shrimp fry, which can be advanced by one month compared to the normal breeding cycle. This can improve the survival rate of shrimp fry, enhance the physical fitness of shrimp fry, and obtain uniformly sized seedlings, making it particularly suitable for large-scale breeding and production of Procambarus clarkii in northern cold regions. Furthermore, the juvenile shrimp obtained by this method can be further cultured in ponds or rice fields to obtain large-sized seedlings, meeting the market demand for cold-region Procambarus clarkii seedlings, improving economic benefits, and reducing breeding risks. Finally, a portion of the large-sized seedlings obtained by this method are retained and continued to be cultured in ponds to obtain commercial shrimp. These can also be used as broodstock for artificial propagation, resulting in a Procambarus clarkii breeding population adapted to the cold climate, enabling the sustainable development of the Procambarus clarkii industry in cold regions. The present invention also has the advantages of extending the breeding period, convenient operation and management, mass production, good efficiency, short time, and low cost, making it suitable for promotion and application in cold regions, promoting the development of the cold-region Procambarus clarkii industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of the shrimp nest corrugated plate in Example 1;

[0025] Figure 2 Schematic diagram of the distribution of shrimp nests and sunshade nets in the deep water area in Example 1, in which 1 represents the deep water area, 2 represents the shrimp nest corrugated plate, and 3 represents the sunshade net;

[0026] Figure 3This is a screenshot of the cross section of the deep water area of the greenhouse and the pond outside the greenhouse in Example 1; where 1 represents the deep water area, 4 represents the greenhouse, 5 represents the pond outside the greenhouse, 6 represents the gentle slope between the deep water area dam and the initial pond dam, 7 represents the dam of the initial pond, 8 represents the water level line of the deep water area, and 9 represents the water level line of the pond outside the greenhouse;

[0027] Figure 4 It is a top view of the deep water area of the greenhouse and the pond outside the greenhouse in Example 1; 7 represents the dam of the initial pond, 5 represents the pond outside the greenhouse, 10 represents the greenhouse dam, 1 represents the deep water area, 11 represents the dam on the side of the greenhouse close to the pond, and 7 represents the dam of the initial pond. DETAILED DESCRIPTION

[0028] Specific embodiment 1: This embodiment is a cold-region crayfish staged breeding method specifically carried out according to the following steps:

[0029] 1. Preliminary preparations:

[0030] ① Pond reconstruction: A deep water area with an area of 1 mu and a depth of 0.5 m was excavated on one side of the original pond, which covers an area of 10 mu and is 2 m deep. A simple greenhouse was built on the deep water area, and the excavated soil was used as a dam for the deep water area. The dam was 1 m high, with a slope ratio of 1:1 and a width of 1 m. An operating area was designated within the greenhouse within the deep water area, connected to the dam of the original pond via a gentle slope.

[0031] ② Preparation of simple greenhouse in deep water area: Before winter, fix a simple sunshade bracket outside the operation area in the greenhouse. The bracket is a steel pipe structure with a height of 2.5m. In mid-March of the following year, install the greenhouse film outside the simple greenhouse.

[0032] ③ Deep water area water injection: Inject groundwater treated by a filtration system or fishery water that meets aquaculture standards into the deep water area to form a fish pond; install aeration equipment in the fish pond, control the water temperature at above 8°C, and seal the injection and discharge outlets with screens;

[0033] 2. Building an ecological water environment:

[0034] Plant aquatic plants that account for 50% of the total volume of the water body in deep water areas, add biological agents to the water to regulate water quality, cultivate natural bait, and build a green ecological aquaculture environment;

[0035] 3. Set up shrimp nests and shade nets:

[0036] Several shrimp nest corrugated boards are placed horizontally in a deep water area to form artificial nests. The shrimp nest corrugated boards are made of PVC and are 1 meter long, 0.3 meters wide, and 3 centimeters high. The shrimp nest corrugated boards are located on the same plane, and adjacent shrimp nests are staggered. Black sunshade nets are placed at the staggered positions, and the black sunshade nets occupy 20% of the area of the deep water area.

[0037] 4. Disinfection and stocking of shrimp fry:

[0038] After slowing down, the shrimp fry are placed in deep water; the stocking density is 300,000 per mu; slowing down the fry: place the plastic bag or basin containing the shrimp fry in water that is the same temperature as the fish pond for 5 to 10 minutes. After the water temperature is balanced, slowly pour the shrimp fry and the water into the fish pond;

[0039] 5. The first stage of breeding and artificial management:

[0040] The shrimp fry are not fed for two days after entering the pond; feeding begins on the third day, and each cycle lasts for seven days. Within each cycle, pellet feed is fed for the first three days, animal bait is fed on the fourth day, pellet feed is fed on the fifth and sixth days, and bio-based bait is fed on the seventh day. The daily feeding amount within a cycle is 3-5% of the shrimp's body weight, and the feeding time is once in the morning and evening, with 30% of the daily feeding amount in the morning and 70% of the daily feeding amount in the evening. The dissolved oxygen content in the water is controlled at above 4mg / L using nano-aerators.

[0041] 6. Preparation of the outdoor pond: When the outdoor minimum temperature reaches 5°C or above, add groundwater to the outdoor pond, plant aquatic plants, place a sunshade net, and prepare low-temperature fertilizer and water. The sunshade net should occupy 30% of the outdoor pond area.

[0042] 7. Second stage of breeding and manual management: When the shrimp fry in the deep water area grow to more than 3cm and the outdoor water temperature is above 12℃, add water to the deep water area and the pond outside the shed to ensure that the temperature difference does not exceed 3℃; this allows the shrimp in the deep water area to climb over the low dam and enter the pond outside the shed for the second stage of breeding; continue manual management;

[0043] 8. Pond division: From May to June, when the shrimp fry grow to 5-8 cm, most of them are gradually caught with ground traps and placed in ponds or rice fields for commercial shrimp farming;

[0044] 9. The third stage of breeding: the remaining shrimp fry continue to be cultured in the pond and continue to be managed manually; in September, the shrimp weight reaches more than 35g, completing the stage-by-stage breeding of cold-region crayfish.

[0045] In this embodiment, the water injection and drainage outlet is sealed with a screen net to prevent shrimp from escaping and other organisms from entering.

[0046] In step 4 of this embodiment, before acclimatization, salt is added into the water bag for transporting the shrimp fry to make the concentration of salt 0.2%.

[0047] This embodiment proposes a method for staged cultivation of cold-region Procambarus clarkii. This method can not only improve the survival rate of Procambarus clarkii seedlings and solve the problem of large-scale cultivation of cold-region Procambarus clarkii seedlings, but also obtain high-quality commercial shrimp or broodstock, promote the high-quality development of the cold-region Procambarus clarkii industry, and improve economic and social benefits.

[0048] This method involves a freshwater commercial shrimp farming method. A greenhouse is constructed on the site of an existing pond. A deepwater pond is installed within the greenhouse, equipped with aeration equipment and planted with aquatic plants, with the plants occupying 50% of the deepwater area. Shrimp nests and shade nets are also installed. The water quality is artificially regulated, creating a green, ecological aquaculture environment that allows shrimp fry to grow healthily once released into the waters. Through feeding and artificial cultivation, high-quality juvenile shrimp, measuring 3 to 4 cm in length, are harvested in batches. This represents the first stage of aquaculture. The deepwater area is then flooded with water, flooding the low dam to connect it with the pond outside the greenhouse. The shrimp fry migrate from the deepwater area inside the greenhouse to the pond outside, where they are further cultured until their survival rate exceeds 85% and their length reaches 5 to 8 cm. This represents the second stage of aquaculture. The fry are then harvested and released into ponds and rice paddies for large-scale commercial shrimp farming. The remaining shrimp continue to be farmed until they weigh 35 grams or more and can be sold or used as broodstock for seed preservation. This represents the third stage of aquaculture.

[0049] Specific embodiment 2: This embodiment differs from Specific embodiment 1 in that the simple greenhouse frame described in step 1 is made of steel, iron, or wood; in mid-March, it is covered with three layers of plastic film, with gaps between the films; an insulation board is installed in the area facing away from sunlight; and a geotextile is covered over the film, which is then covered at night to insulate the pool water. All other aspects are the same as Specific embodiment 1.

[0050] Specific embodiment three: The difference between this embodiment and specific embodiment one or two is that: in step one, the water depth of the deep water zone is kept at 80 cm, the oxygenation equipment is composed of an air pump and a nano oxygenation disk, the air pump and the nano oxygenation disk are connected by an air pipe, and the nano oxygenation disk is set in the deep water zone. 2 A nano oxygenation disk is provided. Other aspects are the same as those of the first or second embodiment.

[0051] Specific embodiment 4: This embodiment differs from Specific embodiments 1 to 3 in that the aquatic plant in step 2 is Elodea nutans, and the biological preparation includes algae source, shrimp peptide fertilizer, EM bacteria, brown sugar, and biofloc. Otherwise, it is the same as Specific embodiments 1 to 3.

[0052] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the algae source is green algae or diatoms, and the amount of algae added is 0.075g / m 3 The dosage of peptide fertilizer for shrimp is 20-30g / m 3 EM bacteria dosage is 2mL / m 3 , the dosage of brown sugar is 10g / m 3 , the dosage of biofloc is 1g / m 3 The rest is the same as that of Specific Embodiments 1 to 4.

[0053] In this embodiment, shrimp fry are released into the deep water area and then added every three days.

[0054] Bioflocs can not only regulate water quality, but also be used as bait to promote the growth of shrimp fry.

[0055] Specific embodiment 6: This embodiment differs from Specific embodiments 1 to 5 in that the animal bait in step 5 is minced fish or snail meat; the plant bait is soybeans or oats; and the pelleted feed comprises, by weight, 13 parts imported fish meal, 8 parts shrimp meal, 10 parts fermented soybean meal, 13 parts soybean meal, 7 parts domestically produced puffed soybeans, 10 parts rapeseed meal, 10 parts oil bran, 5 parts puffed corn, 18 parts second-grade flour, 1 part soybean oil, 1.5 parts phospholipid oil, 4 parts multivitamin and multimineral premix, and 0.05 parts DL-methionine. Other aspects are the same as Specific embodiments 1 to 5.

[0056] Specific embodiment 7: This embodiment differs from any one of specific embodiments 1 to 6 in that the aquatic plants planted in the pond outside the shed in step 6 are Elodea nutans, Vallisneria sinensis, and Potamogeton crispus, in a ratio of 1:1:1, occupying 50% of the area of the pond outside the shed. Other aspects are the same as those of specific embodiments 1 to 6.

[0057] Specific Embodiment 8: This embodiment differs from Specific Embodiments 1 to 7 in that, in step 7, water is added to the deep water area and the pond outside the greenhouse, ensuring a temperature difference of no more than 3°C. The greenhouse film on both sides is rolled up 1.5 meters, and water is slowly added until it overflows the lowest dam, allowing the water in the deep water area and the water in the pond outside the greenhouse to intersect. The water level inside the greenhouse reaches 2.0 meters, and the water level in the pond outside the greenhouse reaches 1.5 meters, allowing the shrimp to migrate from the deep water area to the pond outside the greenhouse for the second stage of cultivation. Other aspects are the same as Specific Embodiments 1 to 7.

[0058] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that in step 8, when the shrimp fry grow to 5-8 cm, 90% of the shrimp fry are gradually caught using ground traps and placed in a 40-mu pond or 400-mu rice field for commercial shrimp farming. Otherwise, this embodiment is the same as specific embodiments 1 to 8.

[0059] The following examples are used to verify the beneficial effects of the present invention:

[0060] A staged culture method for cold-region crayfish is specifically carried out according to the following steps:

[0061] 1. Preliminary preparations:

[0062] ① Pond reconstruction: A deep water area with an area of 1 mu and a depth of 0.5 m was excavated on one side of the original pond, which covers an area of 10 mu and is 2 m deep. A simple greenhouse was built on the deep water area, and the excavated soil was used as a dam for the deep water area. The dam was 1 m high, with a slope ratio of 1:1 and a width of 1 m. An operating area was designated within the greenhouse within the deep water area, connected to the dam of the original pond via a gentle slope.

[0063] ②Preparing a simple greenhouse in the deep water area: Before winter, fix a simple sunshade bracket outside the operating area in the greenhouse. The bracket is a steel pipe structure, 2.5 meters high, and 1 meter apart. Cover it with three layers of plastic film in mid-March of the following year, leaving gaps between the films. Install a layer of insulation board in the area facing away from light. Cover the outside of the greenhouse film with a layer of geotextile, and cover it at night to keep the pool water warm.

[0064] ③ Deep water area water injection: inject groundwater treated by the filtration system or fishery water that meets the aquaculture standards into the deep water area to form a fish pond; install oxygenation equipment in the fish pond and nano oxygenation disk in the deep water area, and 2 A nano-aerator tray with a diameter of 1.2m and a spacing of 5 to 8m between adjacent trays is installed to ensure the oxygen supply in the pond water. The air inlet of the nano-aerator tray is connected to the air outlet of the air pump via an air pipe. The water temperature in the deep water zone is controlled above 8°C. The water level for fishery water is 0.8m high. The groundwater treated by the filtration system meets the standard "Fishery Water Quality Standard" GB11607-89. Water inlets and outlets are set in the deep water zone and sealed with plastic screens to prevent shrimp from escaping or other organisms from entering.

[0065] 2. Building an ecological water environment:

[0066] Elodea, algae source, shrimp peptide fertilizer, EM bacteria, brown sugar and bioflocs were placed in the deep water area, with Elodea accounting for 70% of the total water volume; the algae source was green algae or diatom, and the amount of algae added was 0.075g / m 3 The dosage of peptide fertilizer for shrimp is 20-30g / m 3 EM bacteria dosage is 2mL / m 3 , the dosage of brown sugar is 10g / m 3 , the dosage of biofloc is 1m 3 Shrimp peptide fertilizer was purchased from Wuhan Keyang Bioengineering Co., Ltd.; biofloc was purchased from Dalian Shengtai Aquatic Feed Co., Ltd.

[0067] 3. Set up shrimp nests and shade nets:

[0068] Several shrimp nest corrugated boards are placed horizontally in a deep water area to form artificial nests. The shrimp nest corrugated boards are made of PVC and are 1 meter long, 0.3 meters wide, and 3 centimeters high. The shrimp nest corrugated boards are located on the same plane, and adjacent shrimp nests are staggered. Black sunshade nets are placed at the staggered positions, and the black sunshade nets occupy 20% of the area of the deep water area.

[0069] 4. Disinfection and stocking of shrimp fry:

[0070] In March 2021, the Cold Region Shrimp Research Center of the Harbin Academy of Agricultural Sciences began cultivating Procambarus clarkii seedlings. After slowing down 60,000 shrimp seedlings, they were stocked in deep water. The stocking density was 300,000 shrimp per mu. The slowing down process involved placing the plastic bag or basin containing the shrimp seedlings in water that was isothermal to the pond for 5-10 minutes. After the water temperature had reached equilibrium, the shrimp seedlings were slowly poured into the pond along with the water.

[0071] 5. The first stage of breeding and artificial management:

[0072] The shrimp fry are not fed for 2 days after entering the pond; they are fed starting from the 3rd day, and a cycle is 7 days; in a cycle, pellet feed is fed for the first 3 days, animal bait is fed on the 4th day, pellet feed is fed on the 5th and 6th days, and physical bait is fed on the 7th day; the daily feeding amount in a cycle is 3-5% of the shrimp body weight, and the feeding time is once in the morning and once in the evening, 30% of the daily feeding amount in the morning and 70% of the daily feeding amount in the evening; the dissolved oxygen content in the water is controlled at 4mg / L by the nano aeration disk; the nano aeration disk can both increase oxygen and promote the flow of water. The water quality status is also monitored, and the indicators include water temperature, dissolved oxygen, pH value, nitrite, ammonia nitrogen and other indicators. If the water quality indicators are not good, different preparations need to be added according to the specific situation to improve the water quality; the animal bait is fish meat paste or snail meat paste; the plant bait is cooked chopped soybeans and oats;

[0073] The pellet feed includes, by weight: 13 parts of imported fish meal, 8 parts of shrimp meal, 10 parts of fermented soybean meal, 13 parts of soybean meal, 7 parts of domestic puffed soybeans, 10 parts of rapeseed meal, 10 parts of oil bran, 5 parts of puffed corn, 18 parts of second-grade flour, 1 part of soybean oil, 1.5 parts of phospholipid oil, 4 parts of multivitamin and multi-mineral premix (Tianjin Zhengda Feed Technology Co., Ltd.), and 0.05 parts of DL-methionine. The nutritional components of the pellet feed are: 33.2% protein, 7.4% fat, 2.1% lysine, 0.7% methionine, 1.1% threonine, 0.5% cystine, 1.2% methionine, 1.8% arginine, 1.3% valine, 0.3% proline, 0.3% tryptophan, 1.2% salt, 1.5% starch, 6.4% crude ash, and 4.6% crude fiber. The feeding amount is determined based on the shrimp fry's condition and water temperature.

[0074] 6. Preparation of the outdoor pond: When the outdoor minimum temperature reaches 5°C or above, add groundwater to the outdoor pond, plant aquatic plants, place a sunshade net, and prepare low-temperature fertilizer and water. The sunshade net should occupy 30% of the outdoor pond area.

[0075] 7. Second stage of breeding and manual management: When the shrimp fry in the deep water area grow to more than 3cm and the outdoor water temperature is above 12℃, add water to the deep water area and the pond outside the shed to ensure that the temperature difference does not exceed 3℃; this allows the shrimp in the deep water area to climb over the low dam and enter the pond outside the shed for the second stage of breeding; continue manual management;

[0076] 8. Pond division: From May to June, when the shrimp fry grow to 5-8 cm, most of them are gradually caught with ground traps and placed in ponds or rice fields for commercial shrimp farming;

[0077] 9. The third stage of breeding: the remaining shrimp fry continue to be cultured in the pond and continue to be managed manually; in September, the shrimp weight reaches more than 35g, completing the stage-by-stage breeding of cold-region crayfish.

[0078] After the first stage of culture, the crayfish reached a length of 3-4 cm, with a survival rate of 85%. Once the outdoor pond water temperature reached above 10°C, water from the reservoir was slowly added to both the deepwater area and the pond outside the greenhouse, maintaining a temperature difference of less than 3°C. Once the water overflowed the lower dam, the greenhouse film was raised 10 cm to allow the shrimp to crawl out freely. Manual management was the same as for deepwater culture.

[0079] The second stage of aquaculture is similar to the above. Procambarus clarkii can reach a length of 5 to 8 cm, with a survival rate of 70 to 80%. Most of the shrimp are harvested and then released into ponds or rice fields for commercial shrimp farming.

[0080] The remaining shrimps can be caught and sold as commercial shrimps after the third stage of cultivation of about 70 to 90 days. When the shrimp weight reaches 35 grams per tail or above, they can also be used as breeding shrimps for artificial reproduction to obtain seedlings and cultivate a group of Procambarus clarkii suitable for cold areas.

Claims

1. A cold-region crayfish staged culture method, characterized in that The staged culture method of cold-region crayfish is specifically carried out in the following steps:

1. Preliminary preparations: ① Pond reconstruction: A deep water area with an area of 1 mu and a depth of 0.5 m was excavated on one side of the original pond, which covers an area of 10 mu and is 2 m deep. A simple greenhouse was built on the deep water area, and the excavated soil was used as a dam for the deep water area. The dam was 1 m high, with a slope ratio of 1:1 and a width of 1 m. An operating area was designated within the greenhouse within the deep water area, connected to the dam of the original pond via a gentle slope. ② Preparation of simple greenhouse in deep water area: Before winter, fix a simple sunshade bracket outside the operation area in the greenhouse. The bracket is a steel pipe structure with a height of 2.5m. In mid-March of the following year, install the greenhouse film outside the simple greenhouse. ③ Deep water area water injection: Inject groundwater treated by a filtration system or fishery water that meets aquaculture standards into the deep water area to form a fish pond; install aeration equipment in the fish pond, control the water temperature at above 8°C, and seal the injection and discharge outlets with screens; 2. Building an ecological water environment: Plant aquatic plants that account for 50% of the total volume of the water body in deep water areas, add biological agents to the water to regulate water quality, cultivate natural bait, and build a green ecological aquaculture environment; 3. Set up shrimp nests and shade nets: Several shrimp nest corrugated boards are placed horizontally in a deep water area to form artificial nests. The shrimp nest corrugated boards are made of PVC and are 1 meter long, 0.3 meters wide, and 3 centimeters high. The shrimp nest corrugated boards are located on the same plane, and adjacent shrimp nests are staggered. Black sunshade nets are placed at the staggered positions, and the black sunshade nets occupy 20% of the area of the deep water area.

4. Disinfection and stocking of shrimp fry: After acclimation, stock the crayfish fry in deep water; the stocking density is 300,000 per mu. Acclimation steps: Place the plastic bag or basin containing the shrimp fry in water that is the same temperature as the fish pond for 5-10 minutes. After the water temperature is balanced, slowly pour the shrimp fry and water into the fish pond; 5. The first stage of breeding and artificial management: The shrimp fry are not fed for two days after entering the pond; feeding begins on the third day, and each cycle lasts for seven days. Within each cycle, pellet feed is fed for the first three days, animal bait is fed on the fourth day, pellet feed is fed on the fifth and sixth days, and plant bait is fed on the seventh day. The daily feeding amount within a cycle is 3-5% of the shrimp's body weight, and the feeding time is once in the morning and evening, with 30% of the daily feeding amount in the morning and 70% of the daily feeding amount in the evening. The dissolved oxygen content in the water is controlled at above 4mg / L using nano-aerators.

6. Preparation of the outdoor pond: When the outdoor minimum temperature reaches 5°C or above, add groundwater to the outdoor pond, plant aquatic plants, place a sunshade net, and prepare low-temperature fertilizer and water. The sunshade net should occupy 30% of the outdoor pond area.

7. Second stage of breeding and manual management: When the shrimp fry in the deep water area grow to more than 3cm and the outdoor water temperature is above 12℃, add water to the deep water area and the pond outside the shed to ensure that the temperature difference does not exceed 3℃; this allows the shrimp in the deep water area to climb over the low dam and enter the pond outside the shed for the second stage of breeding; continue manual management; 8. Pond division: From May to June, when the shrimp fry grow to 5-8 cm, most of them are gradually caught with ground traps and placed in ponds or rice fields for commercial shrimp farming; IX. The third stage of culture: The remaining shrimp fry continue to be cultured in the pond and continue to be managed manually; in September, the shrimp weight reaches more than 35g, and the stage culture of cold-region Procambarus clarkii is completed; The types of aquatic plants planted in the pond outside the shed in step 6 are Elodea, Vallisneria and Potamogeton crispus, with a ratio of 1:1:1, accounting for 50% of the area of the pond outside the shed.

2. A cold-region crayfish staged culture method according to claim 1, characterized in that The frame of the simple greenhouse described in step one is made of steel, iron or wood; it is covered with three layers of plastic film in mid-March, with gaps left between the films; a layer of insulation board is added to the part facing away from light; a layer of geotextile is covered outside the greenhouse film, and the geotextile is covered at night to keep the pool water warm.

3. The cold-region crayfish staged culture method according to claim 1, characterized in that In step 1, the water depth in the deep water area is kept at 80cm. The oxygenation equipment is composed of an air pump and a nano oxygenation disk. The air pump and the nano oxygenation disk are connected by an air pipe. The nano oxygenation disk is set in the deep water area and is opened every 15~25m. 2 Set up a nano-aerator tray.

4. The cold-region crayfish staged culture method according to claim 1, characterized in that The aquatic plant in step 2 is Elodea nutans, and the biological preparation includes algae source, shrimp peptide fertilizer, EM bacteria, brown sugar and biological flocs.

5. A cold-region crayfish staged culture method according to claim 4, characterized in that The algae source is green algae or diatom, and the amount of algae added is 0.075g / m 3 ; The dosage of peptide fertilizer for shrimp is 20~30g / m 3 EM bacteria dosage is 2mL / m 3 , the dosage of brown sugar is 10g / m 3 , the dosage of biofloc is 1g / m 3 .

6. The cold-region crayfish staged culture method according to claim 1, characterized in that The animal bait in step five is fish paste or snail paste; the plant bait is soybean or oatmeal; the granular feed includes, by weight: 13 parts of imported fish meal, 8 parts of shrimp meal, 10 parts of fermented soybean meal, 13 parts of soybean meal, 7 parts of domestic puffed soybeans, 10 parts of rapeseed meal, 10 parts of oil bran, 5 parts of puffed corn, 18 parts of second-grade flour, 1 part of soybean oil, 1.5 parts of phospholipid oil, 4 parts of multivitamin and multi-mineral premix, and 0.05 parts of DL-methionine.

7. The cold-region crayfish staged culture method according to claim 1, characterized in that In step seven, add water to the deep water area and the pond outside the shed to ensure that the temperature difference does not exceed 3°C. Roll up the film on both sides by 1.5m, and slowly add water to overflow the lowest dam, so that the water in the deep water area and the water in the pond outside the shed intersect. The water level in the shed is 2.0m, and the water level in the pond outside the shed reaches 1.5m, so that the shrimp can crawl from the deep water area to the pond outside the shed for the second stage of breeding.

8. The cold-region crayfish staged culture method according to claim 1, characterized in that In step eight, when the shrimp fry grow to 5-8 cm, 90% of the shrimp fry are gradually caught using ground traps and placed in a 40-mu pond or 400-mu rice field for commercial shrimp farming.

Images