Efficient fry breeding method for same-layer mating and synchronous egg carrying of crayfish in rice field

Abstract

The invention provides a high-efficiency breeding method for crayfish fries through same-layer mating and synchronous egg carrying in a crayfish rice field, and belongs to the technical field of crayfish fries breeding. The method comprises the steps of field engineering transformation and seine arrangement, parent shrimp breeding and mating management, rice harvesting and stubble reserving, water level management, offspring seed breeding and the like. Through the arrangement of the shallow and narrow ditches and the purse seine, parent shrimps are subjected to hole digging and mating on the same-layer slope surface in a centralized mode, the problem of time-space dispersion of hole digging and mating is solved, and the synchronous hole leaving rate of egg-carrying shrimps is increased. In addition, triple synchronization of gonad development, hole digging mating and hole leaving behaviors of parent shrimps is achieved by controlling the irrigation time and the water level of the rice field, batched egg-carrying shrimps can be obtained and used for industrialized breeding, high-quality shrimp seeds with neat specifications can also be provided, the rice field low-cost large-scale breeding technology is innovated, the high-quality egg-carrying shrimps are provided for industrialized breeding, and the economic benefit is increased. A complete intensive production technology system is constructed, the economic and social benefits are remarkable, and sustainable development of the crayfish industry is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of crayfish seed breeding, and particularly relates to an efficient seed breeding method for crayfish in rice fields that mate and incubate eggs synchronously in the same layer. Background Art

[0002] Crayfish, scientific name: Procambarus clarkii, is an important economic crustacean species in my country. In recent years, with the continuous increase in market demand, the crayfish farming industry has developed rapidly. However, the shortage of high-quality seedlings has become a key bottleneck restricting the further high-quality development of the industry. At present, domestic crayfish seedlings mainly rely on self-breeding and self-raising in rice fields. This traditional model has many problems: on the one hand, the deep and wide ring ditch model adopted leads to uneven specifications of parent shrimps, inconsistent gonadal development and maturity, and asynchronous burrowing and mating, which ultimately results in low seedling yield, late emergence, uneven specifications, and difficult to guarantee quality; on the other hand, in traditional farming methods, problems such as unreasonable male-female ratio and insufficient bait occur frequently, which leads to low survival rate of seedlings, making it difficult to meet the market demand for the rapid development of crayfish farming.

[0003] In-depth research has revealed significant temporal and spatial variations in crayfish burrowing and mating. Burrowing locations are affected by water level fluctuations and differences in gonadal development, resulting in a scattered pattern of varying heights within rice paddies. The traditional deep-and-wide ring-ditch shrimp-rice rotation model presents the following major problems in seedling production:

[0004] 1. The burrows for mating are scattered and at different heights. Watering out of the burrows is affected by the water level, making it difficult to achieve synchronized hatching.

[0005] 2. The deep and wide grooves lead to asynchronous and delayed sexual maturity of the parent shrimp;

[0006] 3. Unclear male-female ratio, inconsistent specifications, and high mating mortality;

[0007] 4. If there is insufficient bait after the seedlings emerge, the seedlings are easily killed and the survival rate is low. Summary of the Invention

[0008] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an innovative method for efficient breeding of crayfish seedlings that mate and incubate eggs synchronously in the same layer in rice fields. Through field engineering, shallow narrow ditches are constructed to promote the synchronous development of the gonads of parent shrimps, and a mating layer is formed by setting up a fence to encourage the parent shrimps to dig holes and mate in the same layer, so that shrimps with eggs and shrimp seedlings of uniform specifications can be obtained in batches; by strengthening the cultivation of parents and accurately feeding feeds, the mating ability of male shrimps and the number of eggs incubated by female shrimps are improved, intraspecific killing is reduced, and the survival rate of seedlings is improved.

[0009] To achieve the above-mentioned object, the present invention provides a method for efficiently breeding crayfish seedlings in rice fields by mating and synchronously spawning in the same layer, which is characterized by comprising the following steps:

[0010] Step 1: Field engineering renovation and enclosure setting: shallow narrow ditches are excavated along the inner bottom of the rice field ridge. The shallow narrow ditches are used for drainage and crayfish burrowing. The ridge is strengthened, and enclosure nets are set along the inner side of the ridge. A mating layer is formed on the same slope of the ridge between the enclosure net and the shallow narrow ditch. The mating layer encourages parent shrimp to burrow and mate in the same slope where the enclosure net and the ditch bottom meet.

[0011] Step 2: Parent shrimp cultivation and mating management: Rice seedlings are planted in the rice fields in May. 15-20 days later, healthy parent shrimp are selected and released into the rice fields. The next day, artificial formula feed is fed, and water is added regularly to maintain the water level. The ovarian development of the female shrimp is observed. When the ovaries of the female shrimp develop to stage IV, the fields are drained and exposed to the sun to encourage the parent shrimp to burrow and mate in the mating layer.

[0012] Step 3, rice harvesting and stubble retention: In late September, when the rice is mature, the rice is harvested and the rice straw is retained as stubble. The remaining rice straw is piled into small piles and retained on the rice stubble;

[0013] Step 4: Water level management: After harvesting, dry the fields for 15 to 20 days, then start flooding the base of the enclosure net to submerge all holes, encouraging the eggs or juvenile shrimp to crawl out of the holes, and maintain the water level.

[0014] Step 5, selection of seedling cultivation method: After the shrimps with eggs or young shrimps crawl out of the cave, cultivate seedlings or breed water shrimp seedlings in the rice fields.

[0015] Preferably, in step 1, the paddy field is a paddy field with fertile soil, sufficient water source and flat surface, and the size is 3 to 10 mu.

[0016] Preferably, in step 1, the ridge is 0.8 to 1 m high, 1 to 1.2 m wide, and has a slope ratio of 1:1.

[0017] Preferably, in step 1, the width d of the shallow narrow ditch is 0.4-0.6 m, the depth h1 is 0.3-0.5 m, the water inlet of the shallow narrow ditch is on the ridge, and the drainage outlet is at the lowest point diagonally opposite the water inlet.

[0018] Preferably, in step 1, the height h2 of the mating layer is 0.3-0.5 m, and the height h3 of the enclosure is 0.6-0.8 m.

[0019] Preferably, in step 2, the healthy parent shrimps screened are those with complete appendages, plump meat, and weighing more than 30 g, the ratio of male to female parent shrimps released is 2:1, and the release rate per mu is 280 to 320 shrimps.

[0020] Preferably, in step 2, the protein content of the artificial compound feed is 30-32%.

[0021] Preferably, in step 2, the water level on the field surface is 0.1 to 0.2 m.

[0022] Preferably, in step 3, the rice straw stubble height is greater than or equal to 0.4 m.

[0023] Preferably, in step 5, breeding the shrimp fry includes: collecting the shrimp larvae or larvae after they crawl out of their burrows by trapping them in ground traps or catching them at night, and then breeding the shrimp fry in a factory workshop. During the catching and transportation process, attention should be paid to standardized and gentle operations to avoid mechanical damage to the shrimp fry and improve their survival rate.

[0024] Beneficial effects of the present invention:

[0025] 1. The present invention invents a burrowing and mating layer by constructing shallow and narrow trenches and setting up enclosures, which effectively solves the problem of temporal and spatial discreteness of parent shrimp burrowing and mating, improves the synchronization of parent mating and watering out of the burrow, and greatly improves the efficiency of shrimps carrying eggs or juveniles crawling out of the burrow synchronously.

[0026] 2. The shallow, narrow furrow system of the present invention facilitates the synchronous development and maturation of the gonads of parent shrimp, eliminating the problems of asynchronous and delayed gonadal development in traditional systems caused by wide and deep furrows, resulting in late emergence and uneven seedling size. Furthermore, compared to the system without furrows, the narrow, shallow furrows provide smooth drainage, facilitate sun-drying, prevent brooding, and protect the soil quality and breeding environment.

[0027] 3. The present invention achieves triple synchronization of parent shrimp gonad development, burrowing and mating, and exit behavior by precisely controlling the irrigation time and water level of rice fields. This not only allows for the production of batches of brooding shrimp for factory-scale seedling cultivation, but also provides high-quality shrimp seedlings of uniform specifications, significantly improving the yield and quality of shrimp seedlings and providing strong technical support for the large-scale and intensive development of the crayfish farming industry.

[0028] 4. The present invention innovates the low-cost large-scale seedling cultivation technology in rice fields, and also provides batches of high-quality egg-bearing shrimp for factory breeding. It has completely constructed an intensive production technology system including factory seedling cultivation and rice field seedling cultivation, which has significant economic and social benefits and helps promote the sustainable development of the crayfish industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of the method of the present invention;

[0030] Figure 2 Schematic diagram of the cross section of the rice field slope of the present invention. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0032] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] Example

[0035] like Figures 1-2 A high-efficiency breeding method for crayfish seedlings in rice fields with same-layer mating and synchronous egg-carrying

[0036] Step 1: Field engineering transformation and fence setting

[0037] Rice field selection and preparation

[0038] Select a 5-mu (approximately 1.5-acre) rice paddy with fertile soil, ample water, and a flat surface. Prepare a 0.8-meter-high nylon net for the enclosure, along with an artificial feed containing 30% to 32% protein and traps and other fishing tools.

[0039] Excavation of shallow narrow trenches and construction of mating layers

[0040] A shallow, narrow ditch, 0.5m wide and 0.4m deep, was dug along the inner side of the ridge. The excavated soil was used to reinforce the ridge. The ridge was reinforced to a height of 0.8m and a width of 1m, with a slope ratio of 1:1. The ridge slope formed between the shallow, narrow ditch and the fence was the mating layer, at a height of 0.4m. This mating layer encouraged the parent shrimp to burrow and mate in the same slope where the fence and ditch meet.

[0041] Water supply and drainage system and fence installation

[0042] A water inlet is installed on the ridge, and a drain outlet is set at the lowest point of the opposite corner to ensure precise water level control. A 0.8m high nylon net is set on the inner side of the ridge, 0.4m above the field surface, and tied into the ground to form a solid enclosure to prevent the parent shrimp from escaping.

[0043] Step 2: Parent shrimp cultivation and mating management

[0044] Screening and stocking of parent shrimp

[0045] Twenty days after rice seedlings were transplanted in late May, screening for parent shrimp began. Healthy crayfish with complete appendages, plump flesh, and weighing over 30g were selected as parent shrimp. They were then stocked in shallow, narrow ditches around the rice paddies at a ratio of 2:1 male to female, with a release rate of 300 per mu.

[0046] Feeding and water level control

[0047] Starting from the day after the broodstock are released, they are fed with a 32% protein artificial feed. After the broodstock are released, the water level in the field is maintained at about 0.2m, and the water level in the shallow narrow ditch is maintained at 0.6m.

[0048] Observation and drainage of fields

[0049] Arrange special personnel to regularly observe the development of female shrimp ovaries. When it is found that more than 95% of the female shrimp ovaries have developed to stage IV, it indicates that the parent shrimp gonads are well developed. At this time, drain the fields and dry them to encourage the parent shrimp to dig holes and mate in the mating layer.

[0050] Step 3: Rice Harvesting and Stubble Retention

[0051] Rice harvesting and processing

[0052] After the rice matures in late September, a harvester is used to harvest the rice. The height of the rice straw stubble is controlled at around 0.45m, and the remaining straw is piled into small stacks and retained on the rice stubble.

[0053] Step 4: Water Level Management

[0054] Field drying and water level regulation

[0055] After the rice is harvested, the paddy is sun-dried for about 20 days before flooding begins. Over three days, the water level is gradually increased to the base of the enclosure net, maintaining a water level of approximately 0.4 m in the paddy field. This will submerge all burrows, encouraging the eggs or juvenile shrimp to emerge.

[0056] Step 5: Seedling cultivation

[0057] Shrimp fry hatching in rice fields

[0058] After the shrimps with eggs or juveniles crawl out of the cave, they are incubated in the rice fields. After the shrimps leave the mother's body and start to eat, the amount of artificial compound feed with a protein content of 36% is increased in time.

[0059] Shrimp fry harvesting and assessment

[0060] Traps were used to capture parent shrimp and observe egg-carrying rates. The shrimp fry were harvested at appropriate times and measured to be 2.46 ± 0.41 g, with a weight coefficient of variation below 20%.

[0061] Realize large-scale breeding and improve breeding efficiency

[0062] The present invention excavates shallow, narrow trenches around the rice fields to ensure movement, feeding, and gonadal mating of the parent shrimp. A net is set up on the slope of the inner ridge to create a burrowing mating layer, and the parent shrimp burrow and mate within 1 to 2 days after drainage. Through these technical measures, the present invention eliminates the temporal and spatial discreteness of the parent shrimp's burrowing and mating, concentrating all mating on the mating layer on the inner slope of the ridge. This results in a female shrimp accumulating eggs or larvae at a rate exceeding 95% in late October, shrimp fry weighing 2 to 3 grams in December, a weight coefficient of variation of less than 20%, and a yield of 80,000 to 100,000 shrimp per mu. This invention innovates the large-scale seedling breeding technology in rice fields and can also provide batches of accumulating eggs for factory-scale seedling production.

[0063] Comparative Example 1

[0064] Comparative Example 1 adopts the traditional deep and wide ditch rice and shrimp farming model, and its operation process and time nodes are consistent with the embodiment.

[0065] The results of Example 1 and Comparative Example 1 are shown in the following table:

[0066] Table 1 Comparison of sexual maturity synchronization rate (%) and burrowing range (m) of parent female shrimp

[0067]

[0068] Note: Sexual maturity refers to the development of female shrimp ovaries to stage IV, and burrowing range refers to the distance from the bottom of the ditch to the top of the slope.

[0069] Table 2 Comparison of synchronization rate of brooding shrimp (%) and shrimp seed size (g)

[0070]

[0071] The above comparison results show that the method in the embodiment significantly improves the proportion of synchronous sexual maturity of parent shrimp compared to the traditional rice-shrimp farming model. The synchronous ovulation rate of female shrimp after being put into the water can reach over 95%, and ovulated shrimp can be obtained in batches for factory-based cultivation of water shrimp seedlings. The hatching time of ovulated shrimp is consistent, and the shrimp seedlings are relatively uniform in size, with a weight coefficient of variation of less than 20%. The uniformity of shrimp seedling size is significantly higher than that of the traditional rice-shrimp farming model. The beneficial results in this embodiment show that the method of the present invention has high economic value, can improve the market competitiveness of commercial shrimp, and is suitable for actual production and promotion.

[0072] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A method for efficiently breeding crayfish seedlings by mating and spawning in the same layer of rice fields, characterized by: The following steps are involved: Step 1: Field engineering renovation and fence setting: dig shallow narrow trenches along the inner bottom of the rice field ridge, build a solid ridge, and set fences along the inner side of the ridge. Form a mating layer on the same slope of the ridge between the fences and the shallow narrow trenches; Step 2: Parent shrimp cultivation and mating management: Rice seedlings are planted in the rice fields in May. After 15-20 days, healthy parent shrimp are selected and placed in shallow, narrow trenches. The next day, they are fed with artificial compound feed. Water is added regularly to maintain the water level in the field and the ovarian development of the female shrimp is observed. When the ovaries of the female shrimp develop to stage IV, the fields are drained and sun-dried to promote mating. Step 3, rice harvesting and stubble retention: In late September, when the rice is mature, the rice is harvested and the rice straw is retained as stubble. The remaining rice straw is piled into small piles and retained on the rice stubble; Step 4: Water level management: After harvesting, dry the fields for 15 to 20 days, then begin flooding the base of the enclosure to submerge all holes and maintain the water level. Step 5, seedling cultivation: After the shrimps with eggs or young shrimps crawl out of the caves, cultivate seedlings or breed water shrimp seedlings in the rice fields.

2. The method for efficiently breeding crayfish seedlings by mating and synchronously accumulating eggs in the same layer of rice fields according to claim 1, characterized in that: In step 1, the paddy field is a paddy field with fertile soil, sufficient water source and flat surface, and the size is 3 to 10 mu.

3. The method for efficiently breeding crayfish seedlings by mating and synchronously accumulating eggs in the same layer of rice fields according to claim 1, characterized in that: In step 1, the ridge is 0.8-1 m high, 1-1.2 m wide, and has a slope ratio of 1:

1.

4. The method for efficiently breeding crayfish seedlings by mating and synchronously accumulating eggs in the same layer of a rice field according to claim 1, characterized in that: In step 1, the width d of the shallow narrow ditch is 0.4-0.6 m, the depth h1 is 0.3-0.5 m, the water inlet of the shallow narrow ditch is on the ridge, and the drainage outlet is at the lowest point diagonally opposite the water inlet.

5. The method for efficiently breeding crayfish seedlings by mating and synchronously accumulating eggs in the same layer of a rice field according to claim 1, characterized in that: In step 1, the height h2 of the mating layer is 0.3-0.5 m, and the height h3 of the fence is 0.6-0.8 m.

6. The method for efficiently breeding crayfish seedlings by mating and synchronously accumulating eggs in the same layer of rice fields according to claim 1, characterized in that: In step 2, the healthy parent shrimps selected are those with complete appendages, plump meat, and weighing more than 30 g. The ratio of male to female parent shrimps released is 2:1, and the release rate is 280 to 320 per mu.

7. The method for efficiently breeding crayfish seedlings by mating and synchronously spawning in the same layer of rice fields according to claim 1, characterized in that: In the step 2, the protein content of the artificial compound feed is 30-32%.

8. The method for efficiently breeding crayfish seedlings by mating and synchronously spawning in the same layer of rice fields according to claim 1, characterized in that: In step 2, the water level on the field surface is 0.1 to 0.2 m.

9. The method for efficiently breeding crayfish seedlings by mating and synchronously accumulating eggs in the same layer of rice fields according to claim 1, characterized in that: In step 3, the rice straw stubble height is greater than or equal to 0.4 m.

10. The method for efficiently breeding crayfish seedlings by mating and synchronously accumulating eggs in the same layer of rice fields according to claim 1, characterized in that: In step 5, the breeding of water flower seedlings includes: after the shrimps with eggs or shrimps with juveniles crawl out of the cave, they are collected by trapping them in ground traps or catching them at night, and then placed in a factory workshop to breed water flower seedlings.

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