A method for early-stage crayfish breeding in southwest region

Abstract

The application discloses a kind of southwest region early crawfish partition breeding method, rice field is divided into breeding area and breeding area, breeding area is inserted in late April, and then put seed crawfish;The rice seedling is inserted in late 20 days in breeding area, and the seedling is thickened by early planting, to avoid seed crawfish being damaged when being put;Three times of precipitation in August induces seed crawfish to breed, in combination with rice harvesting, shachang sterilization, drying field fertilizer water and other operations, create suitable breeding environment;From October, cultivate fry in stages, by feeding high-protein feed and fermentation material, guarantee the size of fry to meet the standard;In November, large-size fry in breeding area is transferred to breeding area, low-temperature fermentation material and high-protein feed are combined in winter, and stage-by-stage round capture is started from February next year, and early crawfish is put on the market 15-20 days earlier than traditional mode, and large crawfish size ratio is significantly improved;Through environmental regulation, accurate feeding and timing optimization, the whole process realizes rice-crawfish symbiosis.

Description

Technical Field

[0001] This invention belongs to the field of crayfish farming technology, specifically relating to a method for the zoned rearing of early-season crayfish in Southwest China. Background Technology

[0002] Over the past decade, Sichuan's crayfish industry has developed rapidly, taking advantage of the unique warm winter climate in southern Sichuan. The province's crayfish farming area has exceeded 1 million mu, with a total output of over 100,000 tons, forming early crayfish farming clusters centered on Yibin, Luzhou, and Suining. Early crayfish from southern Sichuan can be harvested 30-60 days earlier, resulting in a higher premium. In 2026 alone, the output value of the early crayfish industry in Luzhou exceeded 500 million yuan, making it a distinctive pillar industry that drives farmers' income growth.

[0003] However, behind the rapid development of the industry, problems such as germplasm degradation and homogenization of technological models have gradually become prominent. Most crayfish farmers in Sichuan use a "leaving fields and ponds for self-breeding" model, making it difficult to control seedling density. The long-term adverse selection of "catching large and leaving small" has led to severe degradation of shrimp seedling quality, with the proportion of large-sized shrimp continuously decreasing from 2018 to 2025, resulting in a significant decline in per-acre yield. Simultaneously, under the traditional polyculture model, there is a conflict in the time cycle and spatial layout between rice cultivation and crayfish farming, affecting both effective rice tillering and limiting the optimization of the crayfish's growth environment, making it difficult to further advance the market entry time for early-season crayfish.

[0004] Therefore, it is necessary to develop a method for early shrimp farming that separates breeding and rearing zones. By precisely dividing the breeding area and the farming functional area, the timing and technical parameters of broodstock cultivation, seedling propagation and adult shrimp farming can be optimized to bring the early shrimp market time forward by 15-20 days, thereby increasing the proportion of large shrimp and improving the economic benefits of the crayfish industry in Southwest China. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the regional breeding and rearing of early-season crayfish in Southwest China. By dividing the breeding and rearing areas and separating breeding and rearing, and combining this method with the climatic characteristics of Southwest China, the method achieves high yield and improved quality of early-season crayfish. First, the paddy fields are divided into breeding and rearing areas. Rice seedlings are transplanted in the breeding area in late April, followed by the release of broodstock crayfish. Rice seedlings are transplanted 20 days later in the rearing area. Transplanting earlier allows the seedlings to grow thicker and avoids damage to the seedlings when the broodstock crayfish are released. In August, three rainfalls are carried out to induce the breeding of broodstock crayfish. Combined with rice harvesting, disinfection of crayfish ditches, and drying and fertilizing of the fields, a suitable breeding environment is created. From October, crayfish larvae are raised in stages. By feeding them high-protein feed and fermented feed, the size of the larvae is ensured to meet the standards. In November, the large-sized crayfish larvae from the breeding area are transferred to the rearing area. In winter, a combination of low-temperature fermented feed and high-protein feed is used for feeding. From February of the following year, the crayfish are harvested in stages. The early-season crayfish are on the market 15-20 days earlier than the traditional method, and the proportion of large-sized crayfish is significantly increased.

[0006] This invention is achieved through the following technical solution: A method for the regional breeding and rearing of early-season crayfish in Southwest China involves dividing rice paddies into breeding and rearing areas. The breeding area is used for raising broodstock and propagating crayfish larvae, and then the bred larvae are transferred to the rearing area for further rearing. The method includes the following steps: S1: Every April, environmental improvements are made to the fields in the breeding and aquaculture areas, and rice seedlings are transplanted in preparation for the release of broodstock shrimp. S2: In late May, broodstock shrimp are released into the breeding area for broodstock cultivation; S3: Induction and propagation will be carried out in early August, and fertilizer and water management will be implemented. S4: Shrimp larvae are cultivated in early October and harvested at the end of October; S5: In November, the harvested shrimp fry will be released into the aquaculture area for early shrimp farming; S6: Early shrimp harvesting takes place in February of the following year.

[0007] Preferably, the specific methods for modifying the breeding environment in step S1 include: rotary tilling of the field surface, disinfection of shrimp ditches, and rice transplanting in the paddy field; During the rice transplanting process, the breeding area and the aquaculture area are transplanted at different times. The breeding area is transplanted in late April, while the aquaculture area is transplanted 20 days later. After the rice seedlings in the breeding area have survived and reached the effective tillering stage, the broodstock shrimp are released.

[0008] Preferably, in step S2, the specific operation method for releasing broodstock shrimp in the breeding area is as follows: the ratio of male to female broodstock shrimp is 2:1, the weight is more than 20 grams, the body color is dark red or dark red, and 50 catties are released per mu for the first time; organic acids are sprinkled to detoxify the water before releasing the broodstock shrimp, and iodine preparations are used to disinfect the broodstock shrimp when releasing them. The specific method for raising broodstock shrimp is as follows: feed broodstock shrimp feed with a protein content of ≥36%, and mix cooked corn into the feed once a week, with corn accounting for 70% of the total daily feed.

[0009] Preferably, in step S3, the specific method for inducing reproduction is as follows: the water level in the entire field is lowered three times. The first rainfall is carried out in early August, lowering the water level in the field to 20-30cm below the shrimp ditch. The second rainfall is carried out in mid-August, lowering the water level in the shrimp ditch to half of the ditch. The third rainfall is carried out at the end of August, lowering the water level in the shrimp ditch to within 20cm of the bottom of the ditch. After 3 days, the remaining juvenile shrimp and wild fish are disinfected.

[0010] Preferably, during the precipitation-induced reproduction process, the following operations are also required: Rice harvesting: Rice in the breeding area will be harvested during the second and third rainfall periods, and rice in the aquaculture area will be harvested 20 days later. The harvester will be a swallow-and-spit type and a non-chewing type, and the rice stalks will be kept at a height of 40cm. Disinfection of shrimp ditches in shallow water: In conjunction with the third rainfall at the end of August, use 100 catties of quicklime per mu of shrimp ditches to make water and spray it throughout the shrimp ditches. Drying ditches and fields: Completely drain the water from the shrimp ditches and expose them to the sun for 10-12 days until the mud at the bottom of the shrimp ditches or the surface of the fields cracks and turns white, and the rice straw on the surface of the fields turns yellow. Straw piles: Pile rice straw into piles and arrange them neatly in rows with intervals of 6-8 meters. Rotary tillage strips: Rotary tillage strips about 4 meters wide are made every 6-8 meters to facilitate the later transplanting of aquatic plants and the use of ground cages.

[0011] Preferably, in step S3, the specific operation method for fertilizer and water management is as follows: after drying the ditch and field, add water to the field surface and use tea seed cake to kill golden apple snails and wild fish; transplant Elodea in the rotary tillage strips, sow Potamogeton buds, first plant in shallow water and then add water to avoid the aquatic plants floating; apply base fertilizer and farmyard manure, strengthen fertilizer and water management, and when the water temperature drops to 20℃, start using products such as amino acid fertilizer paste, industrial brown sugar or amino acid raw powder to fertilize the water, and maintain the water transparency at 35-40cm.

[0012] Preferably, in step S4, the specific operation method for cultivating shrimp larvae in the breeding area is as follows: strengthen the feeding of small-particle feed and fermented feed, and sprinkle soybean milk or crushed feed of whiteleg shrimp into the whole field once every 5-7 days in the early stage of shrimp larvae. When the shrimp larvae grow to 2cm, feed them palatable small-particle feed with a protein content of ≥36%, and adjust the feeding amount according to their feeding situation. In mid-to-late December, once the water temperature drops below 8℃, fermented feed is introduced. The fermented feed is made by mixing corn, soybeans, soybean meal, oilseed cake, and brown sugar in a mass ratio of 5:2:1:1.5:0.5 and fermenting with yeast. After the start of spring, when the water temperature rises above 10℃, small-particle compound feed is started to be fed to the whole field. The protein content of the small-particle compound feed is ≥36%. Then, depending on the growth, it is gradually switched to adult shrimp feed. The specific operation method for harvesting shrimp larvae in the breeding area is as follows: after the shrimp larvae have been cultivated until the end of October, the broodstock shrimp are harvested. The broodstock shrimp that have finished releasing their offspring are harvested as cleanly as possible and sold using 4.0 or 4.2 mesh traps. From November to mid-December, large-sized shrimp larvae are harvested and transferred to the rearing area using 0.7cm mesh traps. From mid-December to early March of the following year, the remaining shrimp larvae are raised in the original fields. When the water temperature is above 10℃, they are fed in sufficient quantities with high-protein feed with a protein content of ≥36%, once in the morning and once in the evening. From mid-February to early April of the following year, adult shrimp are harvested in rotation with a rest period. Adult shrimp are harvested using 2-3 4.0 or 4.2 mesh traps per mu (unit of land area). After every 5 days of harvesting, the shrimp are rested for 15 days. After the second harvest, depending on the ecological environment of the shrimp pond and the stock density, 30-60 jin (unit of weight) of shrimp fry can be added per mu. By late April, all the shrimp fry in the breeding area are harvested.

[0013] Preferably, in step S5, when releasing the shrimp fry caught in the breeding area into the aquaculture area, 60-80 catties of shrimp fry are released per mu, with a size of 50-100 shrimp fry per catty. Disinfection and stress prevention treatment should be carried out when releasing the shrimp fry.

[0014] Preferably, in step S5, during the early shrimp farming process in the aquaculture area, when the water temperature is higher than 10℃, the shrimp are fed in sufficient quantities with palatable high-protein feed with a protein content of ≥36%, once in the morning and once in the evening; when the water temperature is lower than 10℃, the shrimp are fed with fermented feed combined with high-protein feed, and the protein content of the high-protein feed is ≥36%.

[0015] Preferably, in step S6, the juvenile shrimp released into the aquaculture area in November are harvested in February of the following year. During the early shrimp harvesting process, adult shrimp are harvested in February to early March; rotational harvesting and release are carried out in March to mid-April; and the shrimp in the aquaculture area are completely harvested in mid-April to late April, and any remaining crayfish are killed with pyrethroid agents before the fields are prepared for rice transplanting.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1) In this invention, by dividing the breeding and rearing areas and separating breeding and rearing, combined with the climate characteristics of Southwest China, high yield and quality improvement of early shrimp are achieved. First, the paddy fields are divided into breeding and rearing areas. Rice seedlings are transplanted in late April and then stocked with broodstock shrimp. Rice seedlings are transplanted 20 days later in the rearing area. Transplanting earlier allows the seedlings to grow thicker and avoids damage to the seedlings when stocking with broodstock shrimp. In August, three rainfalls are carried out to induce the breeding of broodstock shrimp. Combined with rice harvesting, shrimp ditch disinfection, and field drying and fertilization, a suitable breeding environment is created. From October, shrimp larvae are cultivated in stages. By feeding high-protein feed and fermented feed, the size of the shrimp larvae is ensured to meet the standards. In November, the large-sized shrimp larvae in the breeding area are transferred to the rearing area. In winter, a combination of low-temperature fermented feed and high-protein feed is used for feeding. From February of the following year, the shrimp are harvested in stages. The early shrimp market time is 15-20 days earlier than the traditional model, and the proportion of large-sized shrimp is significantly increased. The whole process achieves rice-shrimp symbiosis through environmental control, precise feeding and time optimization.

[0017] 2) In this invention, the three-stage precipitation-induced reproduction process simulates natural drought and flood environments, stimulating broodstock shrimp to burrow and mate, thereby increasing the reproduction rate. The shallow shrimp ditches are treated with quicklime and the fields are sun-dried to crack and whiten the silt, which kills harmful organisms such as wild fish and golden apple snails, as well as immature broodstock shrimp that do not burrow. It also effectively improves soil permeability and reduces the accumulation of toxic substances such as hydrogen sulfide. After sun-drying the fields, fertilizer paste and farmyard manure are used in conjunction with water fertilization to maintain water transparency and retain rice stubble of a certain height, allowing shrimp larvae to perch on the top of the rice stubble, providing sufficient planktonic food for shrimp larvae cultivation and improving the survival rate of shrimp larvae. The entire process achieves rice-shrimp ecological symbiosis, ensuring rice yield while improving the breeding efficiency and size quality of crayfish. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Example 1:

[0019] A method for the zoning and rearing of early crayfish in Southwest China involves first dividing rice paddies into breeding and rearing areas. The breeding area is used for the cultivation of broodstock and the propagation of crayfish larvae. The bred larvae are then transferred to the rearing area for further rearing. This zoning method aims to address the problem of an uncontrollable density of larvae leading to a very low proportion of large crayfish under the self-breeding and self-raising model, thereby improving the efficiency of the rearing and rearing process.

[0020] Every April, the breeding environment in the fields of the breeding area is improved, rice seedlings are planted in the fields to prepare for the release of broodstock shrimp; after the remaining crayfish from the previous season in the breeding area are harvested, the fields are placed in shallow water and the surface is tilled.

[0021] In mid-April, the shrimp ditches were cleared of shallow water, with the water level reduced to about 20cm. 15 catties of bleaching powder was sprinkled per mu (0.067 hectares) of shrimp ditches for disinfection.

[0022] From April 20th to April 30th, rice seedlings should be transplanted in shallow water in the paddy fields, using a combination of wide and narrow rows for manual transplanting.

[0023] From May 1st to May 20th, after the rice seedlings have recovered and started to tiller effectively, broodstock shrimp will be released to prevent them from breaking the seedlings.

[0024] In late May, broodstock shrimp were released into the breeding area for cultivation. From May 21st to May 25th, broodstock shrimp weighing over 20 grams with a deep red or dark red body color were released, with a female-to-male ratio of 2:1. The initial stocking density was 50 jin (25 catties) per acre. Before releasing the broodstock shrimp, organic acids were sprayed to detoxify the water, and the shrimp were disinfected with iodine preparations during the release process.

[0025] From May 21 to June 30, broodstock shrimp were raised. To promote gonadal development, broodstock shrimp feed with a protein content of ≥36% was provided. Cooked corn was mixed into the feed and fed once a week, accounting for 70% of the total daily feed. Corn can fatten the broodstock shrimp and promote their growth.

[0026] In mid-to-late June, additional broodstock shrimp will be released. In the planned seedling sales area of ​​the breeding zone, an additional 50 jin of broodstock shrimp can be released per mu, with the same requirements as above.

[0027] From May 1st to August, during the rice growing season, follow the daily management of water and fertilizer control and pest and disease prevention for rice, and wait for the crayfish to grow.

[0028] From August 1st to August 27th, the breeding process was induced by lowering the water level in the entire field three times. The first rainfall around the beginning of autumn in August lowered the water level in the field to 20-30cm below the shrimp ditch, forcing the first batch of seed shrimp to burrow.

[0029] The second rainfall was carried out around the time of the Autumnal Equinox in August, which lowered the water level in the shrimp ditches of the rice-shrimp fields to half the level of the ditches, forcing the second batch of seed shrimp to burrow.

[0030] The third rainfall at the end of August lowered the water level in the rice-shrimp ditches to within 20cm of the bottom of the ditches, forcing the third batch of seed shrimp to burrow.

[0031] Three days later, disinfect the remaining juvenile shrimp and wild fish, and kill the breeding shrimp whose gonads are immature and do not burrow.

[0032] Rice can be harvested during the induced breeding period. The rice harvesting time in the breeding area should be earlier than that in the aquaculture area. The harvester should be a swallow-and-spit type, not a chewing type. The rice stalks should be retained at a height of about 40cm. The purpose of retaining rice stalks in both the breeding and aquaculture areas is that after the fields are flooded, the shrimp larvae can live on the upper part of the rice stalks. When the water is added to about 60cm, the larvae can move around at a depth of about 20cm, forming a shallow water environment with high dissolved oxygen and abundant food, which is conducive to the growth of shrimp larvae.

[0033] From August 25th to August 27th, shallow water in the shrimp ditches will be disinfected. Taking advantage of the third rainfall around August 27th, 100 catties of quicklime will be dissolved in water and sprayed throughout each acre of shrimp ditch to thoroughly kill any burrowing shrimp or other fish in the breeding area, providing a favorable growth environment for the shrimp larvae. For the aquaculture area, since there are no shrimp in the ditches at this time, disinfection can be carried out to provide a healthy living environment for the subsequent transfer of shrimp larvae to aquaculture.

[0034] From August 27th to September 10th, the ditches and fields are dried out completely, and the water in the shrimp ditches is fully exposed to the sun for 10-15 days. The silt at the bottom of the shrimp ditches or on the surface of the fields is dried until it cracks and turns white, and the rice straw on the surface of the fields is dried until it turns yellow. This process sterilizes the shrimp ditches.

[0035] From September 6th to September 8th, rice straw was piled into neat rows, approximately 100cm in diameter and 50cm high, spaced 6-8 meters apart. These rice straw piles provide crayfish with dense hiding spaces, preventing cannibalism and predation, significantly improving survival rates, especially during the crayfish larvae rearing stage. Separately piling the straw also prevents large-scale floating and concentrated rotting, slowing down the decomposition of organic matter and reducing oxygen depletion and the accumulation of toxic substances such as ammonia nitrogen and hydrogen sulfide in the water.

[0036] From September 8th to September 10th, rotary tillage was carried out in long strips, approximately 4 meters wide, spaced 6-8 meters apart. This facilitates the later transplanting of aquatic plants and the installation of traps. Aquatic plants were then planted in the tilled areas, where they readily established themselves. Additionally, the rice stubble was removed after tilling to make it easier to install traps.

[0037] During the shrimp fry rearing period, fertilization, water management and planting of grass are required. From September 20th to September 30th, add water to the field surface to a height of about 30cm. Use tea seed cake to kill golden apple snails and wild fish. At this time, the fry have not yet emerged, so tea seed cake can be used to kill them.

[0038] From October 1st to October 5th, transplant Elodea nuttallii and sow Potamogeton spores. Transplant Elodea nuttallii in rotary tillage strips with a row spacing of 8 meters and a hole spacing of 5 meters, with a hole diameter of 50cm. At the same time, sow Potamogeton spores in the rotary tillage strips. After a week, when the aquatic plants have sprouted new white roots, add water to a height of 60cm. Start with shallow water and then add water to prevent the aquatic plants from floating and dying too early, thereby increasing the survival rate of the aquatic plants.

[0039] From October 15th to October 20th, apply farmyard manure as base fertilizer, preferably cow dung. The manure needs to be sprinkled with microbial inoculants and fermented for about one month in advance. Use a combination of bagged and whole-pond sprinkling methods, applying 300 catties per mu.

[0040] From October 20th to April 1st of the following year, strengthen fertilization and water management. When the water temperature drops to 20℃, start using amino acid fertilizer paste to maintain water transparency at 30-35cm.

[0041] Next, shrimp larvae are raised in the breeding area from October 1st to March 1st of the following year. After the larvae emerge, they are fed small-particle feed and fermented feed. In the early stage, soybean milk or crushed feed for Pacific white shrimp is sprinkled throughout the field every 7 days to provide nutrition for the larvae. When the larvae grow to about 2cm, they are fed palatable small-particle feed with a protein content of ≥36%, and the amount is adjusted according to their feeding behavior. In mid-to-late December, when the water temperature drops below 8℃, fermented feed is fed, supplemented with a small amount of pelleted feed. The fermented feed is made by mixing corn, soybeans, soybean meal, oilseed cake, and brown sugar in a mass ratio of 5:2:1:1.5:0.5 and fermented with yeast. After the beginning of spring, when the water temperature rises to about 10℃, small-particle formulated feed is fed throughout the field, with a protein content of ≥36%. Later, according to the growth status, the feed is gradually switched to adult shrimp feed with a protein content of ≥36%.

[0042] From October 25th to October 31st, the broodstock shrimp will be harvested. 4.2 mesh traps will be used to catch as many broodstock shrimp as possible after they have finished releasing their larvae and sell them, in order to prevent larger shrimp from eating smaller ones.

[0043] Finally, the shrimp larvae are captured and transferred. From November 1st to December 15th, large-sized shrimp larvae are captured using 0.7cm mesh traps and transferred to the rearing area for aquaculture.

[0044] From December 15th to March 1st of the following year, the remaining shrimp larvae in the breeding area are raised in the original fields. When the water temperature is higher than 10℃, they are fed with sufficient amounts of high-protein feed with a protein content of ≥36%, once in the morning and once in the evening. The specific amount of feed is adjusted according to the stock of shrimp and their feeding situation.

[0045] From February 15th to April 10th of the following year, adult shrimp in the breeding area are subject to rotational harvesting and rest periods. Adult shrimp are harvested using three 4.0-mesh traps per acre, with a 5-day harvest followed by a 15-day rest period. After the second harvest, depending on the ecological environment of the shrimp ponds and the stock density, 50 jin of shrimp fry per acre can be added for further cultivation. During the harvesting period, iodine disinfectant is applied twice each month for two consecutive evenings. Example 2:

[0046] This embodiment, based on the above embodiments, further defines the aquaculture process after the shrimp larvae are transferred to the aquaculture area. First, the aquaculture environment in the aquaculture area is modified in a way that differs significantly from that in the breeding area. Mulch and netting are laid on the slopes of the aquaculture area's ridges, and rice planting is staggered. The remaining steps are the same as in the breeding area: rice harvesting using a swallow-and-spit type harvester, with rice stalks retained at approximately 40cm height; shallow water disinfection in the shrimp ditches; drying of the ditches and fields; separate and pile of straw; rotary tillage; application of tea seed cake to kill snails and wild fish; transplanting of Elodea; sowing of Pogostemon cablin spores; and application of base fertilizer, farmyard manure, and amino acid fertilizer paste. Additionally, the aquaculture area needs to be thoroughly disinfected with bleaching powder or polyester pesticides in late April or early May to ensure the absence of original pond larvae, facilitating control of shrimp larvae density during later transfers or stocking, and improving larvae survival rate and quality.

[0047] Subsequently, shrimp fry will be released. From November 1st to December 15th, shrimp fry caught in the breeding area will be released into the aquaculture area. 80 catties of shrimp fry will be released per mu, with a size of 80 shrimp fry per catty. Disinfection and stress prevention treatment are required when releasing the shrimp fry.

[0048] After stocking the shrimp larvae, early shrimp farming should begin. From November 2nd to March 1st of the following year, when the water temperature is above 10℃, feed the shrimp in sufficient quantities with palatable high-protein feed containing ≥36% protein, twice a day, morning and evening. The specific amount of feed should be adjusted according to the stock and feeding behavior. When the water temperature is below 10℃, feed the shrimp with fermented feed mixed with high-protein feed, with the protein content of the high-protein feed being ≥36%. During the farming period, it is necessary to do a good job in water quality control, bottom sediment improvement, aquatic plant maintenance, regular calcium supplementation, and disease prevention.

[0049] Finally, early shrimp harvesting is carried out using a rotational harvesting and release method. From February 15th to February 25th of the following year, adult shrimp in the aquaculture area are harvested, with two 4.0 mesh traps per acre used to harvest and sell the adult shrimp.

[0050] From February 25th to April 10th of the following year, rotational harvesting and stocking were carried out continuously. In early March, depending on the growth of the shrimp, adult shrimp were continuously harvested using 4.0 mesh traps. On March 10th, depending on the stock density after harvesting and the ecological environment of the shrimp pond, about 50 jin of shrimp seedlings were restocked per mu.

[0051] Around April 3rd, adult shrimp were continuously harvested using 4.2 mesh traps. During the harvesting period, iodine disinfectant was applied twice a month, for two consecutive evenings. Shrimp larvae were continuously stocked until April, which produced broodstock shrimp, which could then be recycled to the breeding area for a new round of broodstock farming.

[0052] Finally, the crayfish in the breeding area need to be completely harvested. This should be done from April 10th to April 15th of the following year. In the early stages, taking advantage of rainfall, use three 1.2-mesh traps per acre to catch as many small crayfish and juveniles as possible. Later, disinfect the area while it's still wet, using 40 catties of bleaching powder per acre in combination with pyrethroid pesticides to kill any remaining crayfish, preparing the area for subsequent rice planting. The other parts of this embodiment are the same as the above embodiment and will not be repeated here.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for the regional rearing of early-season crayfish in Southwest China, characterized in that, The rice paddies are divided into breeding and aquaculture zones. The breeding zone is used for raising broodstock shrimp and propagating shrimp larvae. The bred larvae are then transferred to the aquaculture zone for further cultivation. The specific steps include: S1: Every April, environmental improvements and rice planting are carried out on the fields in the breeding and aquaculture areas to prepare for the release of broodstock shrimp. S2: In late May, broodstock shrimp are released into the breeding area for broodstock cultivation; S3: Induction and propagation will be carried out in early August, and fertilizer and water management will be implemented. S4: Shrimp larvae are cultivated in early October and harvested at the end of October; S5: In November, the harvested shrimp fry will be released into the aquaculture area for early shrimp farming; S6: Early shrimp harvesting takes place in February of the following year.

2. The method for regional rearing of early-season crayfish in Southwest China as described in claim 1, characterized in that, In step S1, the specific methods for modifying the breeding environment include: rotary tilling of the field surface, disinfection of shrimp ditches, and rice transplanting in the paddy field; During the rice transplanting process, the breeding area and the aquaculture area are transplanted at different times. The breeding area is transplanted in late April, while the aquaculture area is transplanted 20 days later. After the rice seedlings in the breeding area have survived and reached the effective tillering stage, the broodstock shrimp are released.

3. The method for regional rearing of early-season crayfish in Southwest China as described in claim 1, characterized in that, In step S2, the specific operation method for releasing broodstock shrimp in the breeding area is as follows: the ratio of male to female broodstock shrimp is 2:1, the weight is more than 20 grams, the body color is dark red or dark red, and 50 catties are released per mu for the first time; organic acids are sprinkled to detoxify the water before releasing the broodstock shrimp, and iodine preparations are used to disinfect the broodstock shrimp when releasing them. The specific method for raising broodstock shrimp is as follows: feed broodstock shrimp feed with a protein content of ≥36%, and mix cooked corn into the feed once a week, with corn accounting for 70% of the total daily feed.

4. The method for regional rearing of early-season crayfish in Southwest China as described in claim 1, characterized in that, In step S3, the specific method for inducing reproduction is as follows: the water level in the entire field is lowered three times. The first rainfall is carried out in early August, lowering the water level in the field to 20-30cm below the shrimp ditch. The second rainfall is carried out in mid-August, lowering the water level in the shrimp ditch to half of the ditch level. The third rainfall is carried out at the end of August, lowering the water level in the shrimp ditch to within 20cm of the bottom of the ditch. After 3 days, the remaining juvenile shrimp and wild fish are eliminated.

5. The method for regional rearing of early-season crayfish in Southwest China as described in claim 1, characterized in that, During the precipitation-induced reproduction process, the following operations are also required: Rice harvesting: Rice in the breeding area will be harvested during the second and third rainfall periods, and rice in the aquaculture area will be harvested 20 days later. The harvester will be a swallow-and-spit type and a non-chewing type, and the rice stalks will be kept at a height of 40cm. Disinfection of shrimp ditches in shallow water: In conjunction with the third rainfall at the end of August, use 100 catties of quicklime per acre of shrimp ditches to make water and spray it throughout the entire shrimp ditch. Drying ditches and fields: Completely drain the water from the shrimp ditches and expose them to the sun for 10-12 days until the mud at the bottom of the shrimp ditches or the surface of the fields cracks and turns white, and the rice straw on the surface of the fields turns yellow. Straw piles: Pile rice straw into piles and arrange them neatly in rows with intervals of 6-8 meters. Rotary tillage strips: Rotary tillage strips about 4 meters wide are made at intervals of 6-8 meters to facilitate the later transplanting of aquatic plants and the use of ground cages.

6. The method for regional rearing of early-season crayfish in Southwest China as described in claim 1, characterized in that, In step S3, the specific operation method for fertilizer and water management is as follows: after drying the ditches and fields, add water to the field surface and use tea seed cake to kill golden apple snails and wild fish; transplant Elodea in the rotary tillage strips and sow Potamogeton buds, first transplant the aquatic plants in shallow water and then add water to avoid the aquatic plants floating; apply base fertilizer and farmyard manure, strengthen fertilizer and water management, and when the water temperature drops to 20℃, start using products such as amino acid fertilizer paste, industrial brown sugar or amino acid raw powder to fertilize the water, and maintain the water transparency at 35-40cm.

7. The method for regional rearing of early-season crayfish in Southwest China as described in claim 1, characterized in that, In step S4, the specific operation method for cultivating shrimp larvae in the breeding area is as follows: strengthen the feeding of small-particle feed and fermented feed, and sprinkle soybean milk or crushed feed of whiteleg shrimp into the whole field once every 5-7 days in the early stage of shrimp larvae. When the shrimp larvae grow to 2cm, feed them palatable small-particle feed with a protein content of ≥36%, and adjust the feeding amount according to their feeding situation; In mid-to-late December, once the water temperature drops below 8℃, fermented feed is introduced. The fermented feed is made by mixing corn, soybeans, soybean meal, oilseed cake, and brown sugar in a mass ratio of 5:2:1:1.5:0.5 and fermenting with yeast. After the start of spring, when the water temperature rises above 10℃, small-particle compound feed is started to be fed to the whole field. The protein content of the small-particle compound feed is ≥36%. Then, depending on the growth, it is gradually switched to adult shrimp feed. The specific operation method for harvesting shrimp larvae in the breeding area is as follows: after the shrimp larvae have been cultivated until the end of October, the broodstock shrimp are harvested. The broodstock shrimp that have finished releasing their offspring are harvested as cleanly as possible and sold using 4.0 or 4.2 mesh traps. From November to mid-December, large-sized shrimp larvae are harvested and transferred to the rearing area using 0.7cm mesh traps. From mid-December to early March of the following year, the remaining shrimp larvae are raised in the original fields. When the water temperature is above 10℃, they are fed in sufficient quantities with high-protein feed with a protein content of ≥36%, once in the morning and once in the evening. From mid-February to early April of the following year, adult shrimp are harvested in rotation with a rest period. Adult shrimp are harvested using 2-3 4.0 or 4.2 mesh traps per mu (unit of land area). After every 5 days of harvesting, the shrimp are rested for 15 days. After the second harvest, depending on the ecological environment of the shrimp pond and the stock density, 30-60 jin (unit of weight) of shrimp fry can be added per mu. By late April, all the shrimp fry in the breeding area are harvested.

8. The method for regional rearing of early-season crayfish in Southwest China as described in claim 1, characterized in that, In step S5, when releasing the shrimp fry caught in the breeding area into the aquaculture area, 60-80 catties of shrimp fry are released per mu (unit of land area), with a size of 50-100 shrimp fry per catty. Disinfection and stress prevention treatments are required when releasing the shrimp fry.

9. The method for regional rearing of early-season crayfish in Southwest China as described in claim 1, characterized in that, In step S5, during the early shrimp farming process in the aquaculture area, when the water temperature is higher than 10℃, feed the shrimp with a suitable amount of high-protein feed with a protein content of ≥36% in sufficient quantities, once in the morning and once in the evening; when the water temperature is lower than 10℃, feed the shrimp with fermented feed and high-protein feed, with the protein content of the high-protein feed being ≥36%.

10. The method for regional rearing of early-season crayfish in Southwest China as described in claim 1, characterized in that, In step S6, the juvenile shrimp released into the aquaculture area in November are harvested in February of the following year. During the early shrimp harvesting process, adult shrimp are harvested in February to early March; rotational harvesting and release are carried out in March to mid-April; and the shrimp in the aquaculture area are completely harvested in mid-April to late April, and any remaining crayfish are killed with pyrethroid agents before the fields are prepared for rice planting.