Narrow ditch rice field facility and method for breeding and collecting egg-carrying crayfishes

Abstract

The invention relates to a narrow ditch rice field facility and method for breeding and collecting egg-carrying crayfish, and belongs to the technical field of crayfish fry breeding. The facility comprises a shallow narrow ditch which is circumferentially excavated along the bottom field surface of the inner side of a rice field ridge, an inner ridge is arranged on the inner side of the shallow narrow ditch, and a detachable barrier net is mounted at the top; the outer side is a rice field slope, and an anti-escape net is laid on the rice field slope; artificial shrimp nests are uniformly arranged in the shallow narrow ditches and are formed by connecting a plurality of pipe bodies in parallel, one end of each pipe body is closed, drainage holes are formed in the bottoms of the side walls of the pipe bodies, and soil thin layers are filled in the pipe bodies. The invention further provides a method for breeding and collecting the egg-carrying crayfishes. The method comprises the steps of planting the aquatic plants in the shallow narrow ditches, putting the parent crayfishes in the shallow narrow ditches, lowering water, drying the field in the sun to promote mating, placing the artificial crayfish nests after watering, and collecting the parent crayfishes in the artificial crayfish nests. Through the design of the double purse seine system and the artificial shrimp nest, the problem of escape of the egg-carrying shrimps is effectively solved, the collection efficiency is improved, and meanwhile, a stable and continuous water fry supply source is provided for out-of-season breeding and regional breeding of the crayfishes.

Description

Technical Field

[0001] This invention relates to the field of crayfish seedling breeding technology, specifically to a narrow-ditch paddy field facility and method for breeding and collecting berried crayfish. Background Technology

[0002] Crayfish (scientific name: *Procambarus clarkii*) is the largest farmed crustacean species in my country in terms of both farming area and output. The main farming areas are concentrated in five provinces along the middle and lower reaches of the Yangtze River: Hubei, Anhui, Hunan, Jiangsu, and Jiangxi. In 2024, these five provinces accounted for 90.45% of the national crayfish production. In recent years, crayfish farming has expanded southward and northward, reaching Guangxi, Hainan, and Guangdong in the south, and the three northeastern provinces in the north, gradually achieving staggered farming and market supply. However, the seedlings for this southward and northward crayfish farming need to be obtained from the main production areas in the middle and lower reaches of the Yangtze River. Long-distance transportation of large-sized seedlings (2-5g / fish) results in small transport volumes, low survival rates, and high costs, hindering the healthy development of the farming industry. Larvae, which are 5-10 days old and have completely absorbed their yolk, are capable of independent life activities and are suitable for long-distance transportation with oxygenated water. Therefore, large-scale breeding of larvae has become a key point for the development of crayfish farming in the southward and northward expansion.

[0003] Crayfish are small shrimp species with berried egg-bearing and juvenile-bearing behaviors, carrying 100-800 eggs. The breeding of crayfish larvae requires collecting berried shrimp in a factory-like facility; therefore, a stable supply of larvae depends on the collection and consistent supply of berried shrimp. In conventional rice paddies or ponds, the burrowing of parent crayfish varies with water level and net height, and the maturation and mating of males and females are also random. After flooding, berried shrimp are scattered and difficult to concentrate. Furthermore, the synchronicity of spawning and the uniformity of egg quality are difficult to guarantee, directly impacting the large-scale production of larvae. By constructing U-shaped narrow ditches and netting in rice paddies, the scattered berried shrimp can be concentrated in a specific area, facilitating synchronized breeding and harvesting, thus obtaining a large quantity of synchronously developing berried shrimp. This not only ensures the efficient breeding of crayfish seedlings and supports the "southward and northward" movement of crayfish farming to achieve staggered farming and expand the farming scope, but also provides high-quality seedlings for year-round crayfish farming in the middle and lower reaches of the Yangtze River, promoting the healthy and sustainable development of the crayfish industry. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a narrow-ditch paddy field facility and method for breeding and collecting berried crayfish. By constructing a U-shaped narrow ditch around the paddy field and setting up double nets with escape prevention and barrier functions on the slope and the inner embankment of the paddy field, the mating burrowing of the parent crayfish and the activity range of the berried crayfish are restricted within the U-shaped narrow ditch enclosed by the double nets. By utilizing the burrowing habits of the berried crayfish and artificial crayfish nests, the berried crayfish can be collected in batches.

[0005] To achieve the above objectives, this invention designs a narrow-ditch paddy field facility for breeding and collecting berried crayfish. The facility includes a U-shaped narrow ditch excavated circumferentially along the inner bottom of the paddy field embankment. An inner embankment is provided inside the U-shaped ditch, with a detachable barrier net on top. A paddy field slope is provided outside the U-shaped ditch, and an escape-proof net is installed on the slope. Multiple artificial crayfish nests are placed within the U-shaped ditch. These artificial crayfish nests are placed in the paddy field after it has been flooded.

[0006] Preferably, the artificial shrimp nests are evenly spaced circumferentially within a U-shaped narrow trench, covering the entire trench. Each artificial shrimp nest is composed of several tubes, one end of which is closed, connected in parallel. The closed end of each tube is placed at the bottom of the U-shaped narrow trench, with the open end facing upwards. The tubes are bonded together with an adhesive. By simulating a natural cave environment, these artificial shrimp nests facilitate stable habitat and egg-laying for berried shrimp, thereby improving nest utilization and reproductive success rates.

[0007] Preferably, the pipe is a PVC pipe with a length of 0.3 m and a diameter of 100 mm.

[0008] Preferably, the bottom area of ​​the side wall of the pipe has multiple drainage holes. These drainage holes allow water to drain downwards first when the artificial shrimp nest is lifted, causing the water level inside the pipe to drop slowly. This prevents the entire nest from rushing out of the pipe at once, which could cause the berried shrimp to be washed away and thus maintain the number of eggs carried.

[0009] Preferably, the bottom of the tube is filled with a thin layer of soil. This thin layer of soil enhances the simulation of shrimp nests, induces shrimp to burrow, promotes stable egg laying, and improves collection efficiency.

[0010] Preferably, the escape-proof net is made of an upper plastic net and a lower nylon net sewn together. A tension rope runs through the top of the plastic net. The escape-proof net is equipped with fixed poles every 1-2 meters, each 0.5-1.0 meters high, with 0.1-0.2 meters buried in the soil. The mesh size is 40 mesh. This double-layer structure enhances the escape-proof performance.

[0011] Preferably, the barrier net is equipped with support rods every 1-2 meters, and the barrier net and support rods are fixed together with cable ties. The barrier net is 0.6 meters high with a mesh size of 40 meshes, of which 0.1-0.2 meters are buried in the soil. The barrier net is installed at the edge of the inner embankment closest to the field surface. The barrier net divides the paddy field into an outer breeding zone and an inner aquaculture zone, preventing parent shrimp from entering the aquaculture zone and causing uncontrollable crayfish density issues in the aquaculture zone. This achieves "dual use of one field" and improves the utilization efficiency of the paddy field.

[0012] Preferably, the width w1 of the U-shaped narrow ditch is 0.3~0.6m and the depth h1 is 0.3~0.5m; the top surface width w2 of the inner embankment is 0.2~0.4m and the bottom surface width w3 is 0.4~0.5m; the height h2 of the anti-escape net from the paddy field surface is 0.4~0.6m.

[0013] This invention also designs a method for breeding and collecting berried crayfish, wherein the method involves the following steps in a narrow-ditch rice paddy facility for breeding and collecting berried crayfish: Step S1: Plant aquatic plants in the U-shaped narrow ditch in May or June. After planting the aquatic plants, release the parent shrimp into the U-shaped narrow ditch and start feeding them the next day. Step S2: The August rainfall and drying of the fields encourage the parent shrimp to burrow and mate. After the rice is harvested, the fields are dried for another 3 weeks. Then, the water is raised to 0.3m in one go, which submerges the egg-bearing shrimp out of their burrows. Artificial shrimp nests are placed in a U-shaped narrow ditch to collect the egg-bearing shrimp. Step S3: After placing the artificial shrimp nest, let it stand for 3-5 days; after the egg-bearing shrimp enter the artificial shrimp nest, lift the artificial shrimp nest, collect the parent shrimp in the artificial shrimp nest, and send the egg-bearing or juvenile female shrimp to the factory workshop to incubate the fry, while the male shrimp and non-egg-bearing female shrimp are returned to the site or given intensive feeding.

[0014] Preferably, in step S1, the aquatic plants are planted when the rice seedlings have tillered and grown to a height of 0.4 m or more in the paddy field, and the water level is above 0.2 m. Timely planting of aquatic plants provides shrimp with a hiding and habitat environment, which helps improve the survival rate and reproductive success rate of parent shrimp. The aquatic plants are heat-resistant *Hydrilla verticillata*, or transplanted water hyacinth, water peanut, and other aquatic plants.

[0015] Preferably, in step S1, the ratio of male to female parent shrimp is 2:1, with 300-500 shrimp per acre, each weighing 35-50 g, and having complete appendages, plump flesh, no external injuries, and strong vitality.

[0016] The beneficial effects of this invention are: 1. This invention innovatively constructs a double-layered enclosure system, consisting of a barrier net and an escape-prevention net. By setting up inner and outer layers of enclosure nets in the flooded area, the emerging berried shrimp are strictly controlled within the safe area of ​​a U-shaped narrow ditch. This design effectively solves the problem of berried shrimp easily spreading and escaping onto the field surface in traditional methods, ensuring both the activity and feeding space of the berried shrimp and significantly improving collection efficiency, avoiding collection difficulties caused by the dispersion of shrimp populations.

[0017] 2. This invention establishes a stable and continuous supply of broodstock crayfish fry through centralized cultivation and collection. This fundamental guarantee provides core support for off-season crayfish farming and lays a key foundation for regionalized crayfish farming through long-distance transportation of fry.

[0018] 3. This invention uses PVC water pipes to simulate natural shrimp nests, utilizing the burrowing and hatching habits of berried shrimp to achieve automatic and rapid collection. Compared with traditional trap fishing methods, this artificial shrimp nest not only avoids physical damage to berried shrimp during the fishing process, but also effectively reduces fighting among berried shrimp due to space competition. By protecting individuals and reducing interference, it significantly improves the survival rate of berried shrimp and their eggs.

[0019] 4. This invention uses the barrier netting on the inner ridge as a boundary to clearly divide the paddy field into two parts: the ring ditch within the double netting serves as the breeding area, while the surface area serves as the aquaculture area, successfully achieving "dual use of one field." This design represents another breakthrough in the separation of crayfish breeding and aquaculture. On the one hand, it eliminates interference from residual crayfish larvae in the aquaculture area, improving the size of adult crayfish through precise stocking; on the other hand, it effectively increases the utilization rate of the paddy field, injecting strong momentum into the large-scale and standardized development of the industry. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the U-shaped narrow ditch in the paddy field according to the present invention; Figure 2 This is a structural diagram of the artificial shrimp nest of the present invention. Figure 3 This is a structural diagram of the escape-prevention net of the present invention; Figure 4 This invention relates to an escape prevention net; Figure 5 This is a flowchart of the method of the present invention.

[0021] Figure label: 1 U-shaped narrow trench 2 inner ridge, 3. Barrier netting, 31. Support poles, 32. Cable ties, 4. Rice paddy slopes 5. Escape-proof netting; 51. Plastic netting; 511. Tensioning rope; 52. Nylon netting; 53. Fixing pole. 6 Artificial shrimp nest, 61 Pipe body, 611 Drainage hole, 612 Soil layer, 62 Adhesive. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0023] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0024] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0026] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of 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 "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1 like Figures 1-4 The narrow-ditch paddy field facility shown includes a U-shaped narrow ditch 1 dug along the inner side of the paddy field ridge and around the bottom of the paddy field surface. The inner side of the U-shaped narrow ditch 1 is provided with an inner ridge 2. The top of the inner ridge 2 is provided with a detachable barrier net 3. The outer side of the U-shaped narrow ditch 1 is provided with a paddy field slope 4. An escape-proof net 5 is provided on the paddy field slope 4. Multiple artificial shrimp nests 6 are placed in the U-shaped narrow ditch 1.

[0029] Artificial shrimp nests 6 are evenly spaced circumferentially within a U-shaped narrow ditch 1, covering the entire ditch. Each artificial shrimp nest 6 is composed of several tubes 61, each closed at one end, connected in parallel. The closed end of each tube 61 is placed at the bottom of the U-shaped narrow ditch 1, with the open end facing upwards. The tubes 61 are bonded together with adhesive 62. Multiple drainage holes 611 are provided in the bottom area of ​​the side wall of each tube 61. A thin layer of soil 612 is filled inside each tube 61. Each tube is a 0.3 m long, 100 mm diameter PVC pipe. Each artificial shrimp nest 6 is composed of twelve tubes bonded together, but the number of tubes can be adjusted according to actual needs.

[0030] The escape-prevention net 5 is made of an upper plastic net 51 and a lower nylon net 52 sewn together. A tension rope 511 runs through the top of the plastic net 51. The escape-prevention net 5 is equipped with a fixing rod 53 every 1-2 meters. The escape-prevention net 5 and the fixing rod 53 are bound together with wire. The escape-prevention net 5 is 0.5-1.0 m high, with 0.1-0.2 m buried in the soil. The mesh size is 40 mesh. The barrier net 3 is equipped with a support rod 31 every 1-2 meters. The barrier net 3 and the support rod 31 are fixed together with cable ties 32. The barrier net 3 is 0.6 m high, with a mesh size of 40 mesh. 0.1-0.2 m is buried in the soil. The barrier net 3 is installed at the edge of the inner embankment 2 closest to the field surface. The width w1 of the U-shaped narrow ditch 1 is 0.3~0.6m, and the depth h1 is 0.3~0.5m; the top width w2 of the inner embankment is 0.2~0.4m, and the bottom width w3 is 0.4~0.5m; the height h2 of the anti-escape net 5 from the paddy field surface is 0.4~0.6m.

[0031] This facility, by setting up inner and outer layers of netting in the flooded area, including a barrier net (3) and an escape-prevention net (5), strictly controls the emerging berried shrimp within the safe area of ​​a U-shaped narrow ditch. This effectively solves the problem of berried shrimp easily spreading and escaping onto the field surface, a problem that is common in traditional methods. It ensures the activity and feeding space for the berried shrimp while significantly improving collection efficiency and avoiding collection difficulties caused by the dispersion of shrimp populations. Simultaneously, PVC water pipes are used to simulate natural shrimp nests. By utilizing the burrowing and hatching habits of the berried shrimp after the water level rises, the facility enables automatic and rapid collection of the berried shrimp. Compared to traditional trapping methods, this artificial shrimp nest not only avoids physical damage to the berried shrimp during the harvesting process but also effectively reduces fighting among them due to space competition. By protecting individuals and minimizing disturbance, it significantly improves the survival rate of both the berried shrimp and their eggs.

[0032] Example 2 like Figure 5 The method for breeding and collecting egg-bearing crayfish shown is performed sequentially in the narrow-ditch rice paddy facility of Example 1 as follows: Step S1: Planting aquatic plants and releasing broodstock shrimp: Plant aquatic plants in the U-shaped narrow ditch 1 in May or June. After planting the aquatic plants, release the broodstock shrimp into the U-shaped narrow ditch 1 and start feeding them the next day. Plant the aquatic plants when the rice seedlings in the paddy field have tillered and grown to a height of more than 0.4 m and the water level is more than 0.2 m. The aquatic plants are heat-resistant Hydrilla verticillata, or some water hyacinth, water peanut and other aquatic plants can be transplanted. The ratio of male to female broodstock shrimp is 2:1, with 300-500 shrimp per acre. Each shrimp should weigh 35-50 g, have complete appendages, plump flesh, no external injuries, and be vigorous. Step S2: Drying and flooding the field to encourage mating of parent shrimp: Rainfall in August and drying the field encourages parent shrimp to burrow and mate. After the rice harvest, continue drying the field for 3 weeks, then flood it with water to a depth of 0.3m. After the burrows are submerged, artificial shrimp nests 6 are placed in a U-shaped narrow ditch 1 to collect the berried shrimp. The number of artificial shrimp nests 6 is estimated based on the number of parent shrimp released. Step S3: Collect and sort berried shrimp in shrimp troughs: After placing artificial shrimp nests 6, let them stand for 3-5 days; after the berried shrimp enter artificial shrimp nests 6, lift artificial shrimp nests 6, collect the parent shrimp in artificial shrimp nests 6, and send the berried or juvenile female shrimp to the factory workshop to incubate fry, while the male shrimp and non-berried female shrimp are returned to the factory or given intensive feeding.

[0033] This method establishes a stable and continuous supply of broodstock crayfish fry through centralized cultivation and collection. This fundamental guarantee provides core support for off-season crayfish farming and lays a crucial foundation for regionalized crayfish farming via long-distance transportation of fry. Furthermore, the innovative double-enclosure netting system, using the inner embankment as a boundary, clearly divides the farming field into two parts: the ring ditch within the double enclosure serves as the breeding area, while the surface area is used for farming, successfully achieving "dual use of one field." This design represents another innovation in the separation of breeding and farming, effectively improving paddy field utilization and providing strong support for the development of the crayfish farming industry.

[0034] Comparative Example The difference between the comparative example and Example 2 is that the paddy field does not have a double netting system, but only an escape-proof net; the tool used to catch the parent shrimp is a fish trap. The similarities are: the paddy field facilities and area, the number and proportion of parent shrimp released, and the daily management conditions are all the same.

[0035] The results of five consecutive days of collection showed that, in the comparative example, only 139 berried shrimp were collected, with a female recapture rate of 46.33%, and eggs were scraped off the traps. In the example, 266 berried shrimp were collected, with a female recapture rate of 88.67%, and only one berried shrimp was found in each artificial shrimp nest. Because the berried shrimp's activity range is unrestricted, the collection efficiency is significantly reduced. The example, however, effectively improves collection efficiency and the integrity of the berried shrimp, enabling concentrated, efficient, and damage-free collection for factory-scale breeding of fry. Furthermore, in the example, the shrimp fry and parent shrimp in the breeding paddy field did not spread to the surface, allowing for density control during the following year's stocking, thus improving aquaculture efficiency.

[0036] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A narrow-ditch paddy field facility for breeding and collecting berried crayfish, comprising a U-shaped narrow ditch (1) excavated circumferentially along the bottom of the paddy field ridge, characterized in that: The inner side of the U-shaped narrow ditch (1) is provided with an inner embankment (2), the top of the inner embankment (2) is provided with a detachable barrier net (3), the outer side of the U-shaped narrow ditch (1) is provided with a paddy field slope (4), the paddy field slope (4) is provided with an escape prevention net (5), and multiple artificial shrimp nests (6) are placed in the U-shaped narrow ditch (1).

2. The narrow-ditch paddy field facility for breeding and collecting berried crayfish according to claim 1, characterized in that: The artificial shrimp nests (6) are evenly spaced along the circumference in the U-shaped narrow trench (1) and are distributed throughout the entire U-shaped narrow trench (1). The artificial shrimp nests (6) are formed by several tubes (61) with one end closed in parallel. The closed end of the tube (61) is placed at the bottom of the U-shaped narrow trench (1) and the open end faces upward. The tubes (61) are fixed together by adhesive (62).

3. The narrow-ditch paddy field facility for breeding and collecting berried crayfish according to claim 2, characterized in that: The bottom area of ​​the side wall of the pipe (61) is provided with multiple drainage holes (611).

4. The narrow-ditch paddy field facility for breeding and collecting berried crayfish according to claim 2, characterized in that: The tube (61) is filled with a thin layer of soil (612).

5. The narrow-ditch paddy field facility for breeding and collecting berried crayfish according to claim 1, characterized in that: The escape-proof net (5) is made of an upper plastic net (51) and a lower nylon net (52) sewn together. The top of the plastic net (51) is provided with a tension rope (511) that runs through the entire plastic net (51). The escape-proof net (5) is provided with a fixing rod (53) every 1~2m. The escape-proof net (5) and the fixing rod (53) are tied together with iron wire. The escape-proof net (5) is 0.5~1.0 m high, of which 0.1~0.2m is buried in the soil, and the mesh size is 40 mesh.

6. The narrow-ditch paddy field facility for breeding and collecting berried crayfish according to claim 1, characterized in that: The barrier net (3) is provided with support rods (31) every 1~2m. The barrier net (3) and the support rods (31) are fixed by cable ties (32). The barrier net (3) is 0.6m high and has a mesh size of 40 meshes. 0.1~0.2m of the mesh is buried in the soil. The barrier net (3) is installed at the edge of the inner ridge (2) near the field surface.

7. The narrow-ditch paddy field facility for breeding and collecting berried crayfish according to claim 1, characterized in that: The width w1 of the U-shaped narrow ditch (1) is 0.3~0.6m and the depth h1 is 0.3~0.5m; the top width w2 of the inner embankment is 0.2~0.4m and the bottom width w3 is 0.4~0.5m; the height h2 of the anti-escape net (5) from the paddy field surface is 0.4~0.6m.

8. A method for breeding and collecting berried crayfish, characterized in that: The following steps are performed sequentially in the narrow-ditch paddy field facility as described in any one of claims 1 to 7: Step S1: Plant aquatic plants in the U-shaped narrow ditch (1) in May to June. After planting the aquatic plants, release the parent shrimp into the U-shaped narrow ditch (1) and start feeding them the next day. Step S2: In August, the rain and drying of the fields caused the parent shrimp to burrow and mate. After the rice was harvested, the fields were dried for another 3 weeks. Then, the water was raised to 0.3m in one go. After the berried shrimp were submerged in their burrows, artificial shrimp nests (6) were placed in a U-shaped narrow ditch (1) to collect the berried shrimp. Step S3: After placing the artificial shrimp nest, let it stand for 3 to 5 days; after the berried shrimp enter the artificial shrimp nest (6), lift the artificial shrimp nest (6), collect the parent shrimp in the artificial shrimp nest (6), and send the berried or juvenile female shrimp to the factory workshop to incubate the fry. The male shrimp and the non-berried female shrimp are returned to the site or given intensive feeding.

9. The method for breeding and collecting berried crayfish according to claim 8, characterized in that: In step S1, the aquatic plants are planted when the rice seedlings have tillered and grown to a height of more than 0.4 m in the paddy field, and the water level is more than 0.2 m above the water surface.

10. The method for breeding and collecting berried crayfish according to claim 8, characterized in that: In step S1, the ratio of male to female parent shrimp is 2:1, with 300-500 shrimp per acre, and each shrimp weighing 35-50 g.

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