Pseudosciaena crocea and portunus trituberculatus polyculture method based on fence net

Abstract

The invention belongs to the technical field of aquaculture, and particularly relates to a large yellow croaker and portunus trituberculatus polyculture method based on a fence net. According to the method, larimichthys crocea fry and portunus trituberculatus fry are subjected to polyculture in a fence net culture facility platform in a sea area; compared with a traditional single culture mode or a pond polyculture mode, the large yellow croaker and portunus trituberculatus polyculture system has the advantages that the space utilization rate is higher, the feed utilization rate is higher, the wind and wave resistance is higher, the culture mode is more ecological, the effects of reducing seabed nutritive salt deposition and preventing and controlling epidemic diseases are achieved, and multi-nutrition-level polyculture of large yellow croakers and portunus trituberculatus is achieved; the invention provides a novel polyculture mode of large yellow croakers and portunus trituberculatus.

Description

Technical Field

[0001] The invention belongs to the technical field of aquaculture, and in particular relates to a polyculture method of large yellow croaker and swimming crab based on a fence net. Background Art

[0002] Pseudosciaena crocea belongs to the class of bony fishes, the order of Perciformes, the family of Sciaenidae. It is one of the four major economic fish species in the East my country Sea. It is very popular among consumers because of its tender and delicious meat and rich protein. The three-tuberculate swimming crab (Portunus trituberculatus) belongs to the class of Crustacea, the order of Decapoda, the family of Portunidae, and the genus of Portunus. It is a species with wide temperature and salinity. It is widely distributed in coastal areas of my country. It is one of the more important economic crabs in the East China Sea and a large marine crab with high economic value. Both Pseudosciaena crocea and three-tuberculate swimming crab are important aquatic products in my country. They have high market demand and can provide considerable economic benefits for farmers.

[0003] With the increasing degree of aquaculture intensification, the constraints on the development of large yellow croaker and swimming crab farming are becoming increasingly apparent, such as limited farming space, frequent outbreaks and epidemics of diseases, etc. Therefore, seeking a more reasonable and efficient large yellow croaker and swimming crab farming model has become an urgent task.

[0004] In the prior art, the mixing technologies of different types of aquaculture species mainly include pond polyculture technology of tilapia and shrimp, polyculture mode of freshwater river crab and fish, and ecological polyculture method of swimming crab, Manila clam and Chinese shrimp in pond. Although some breeding methods have been reported for pond polyculture of yellow croaker and swimming crab, they are all carried out in the breeding environment of pond water. There are no reports on other polyculture modes of yellow croaker and swimming crab, especially multi-trophic level polyculture technology of yellow croaker and swimming crab based on offshore and deep sea breeding platforms. Summary of the invention

[0005] The purpose of the present invention is to provide a polyculture method of large yellow croaker and swimming crab based on a fence net, and the polyculture method provides a breeding method for large yellow croaker and swimming crab in a sea area. The large yellow croaker and swimming crab inhabit different water layers in the sea area, and the breeding space can be fully utilized to realize multi-nutrient level polyculture of large yellow croaker and swimming crab, and the breeding efficiency is better than the traditional single breeding mode, and a new polyculture method of large yellow croaker and swimming crab is provided.

[0006] The present invention provides a method for polyculture of large yellow croaker and swimming crab in sea area, comprising the following steps:

[0007] The large yellow croaker fry and the swimming crab fry are co-cultured in a fence net culture facility platform located in the sea area, and the co-culture management is carried out until they are captured;

[0008] The fence net breeding facility platform is a fence net closed on all sides, including an external skeleton support structure and a breeding net surrounding the external skeleton support structure;

[0009] One end of the external skeleton support structure is inserted into the seabed, and the other end is exposed above the water surface;

[0010] One end of the aquaculture net in the vertical direction is buried in the seabed, with a depth of more than 0.5 meters; the other end is exposed above the water surface, and the height is flush with the height of the external skeleton support structure exposed above the water surface.

[0011] Preferably, the material of the external skeleton support structure includes one or more of iron, cement, stainless steel and steel coated with anti-corrosion and anti-rust paint.

[0012] Preferably, the external skeleton support structure is a columnar structure.

[0013] Preferably, the breeding net comprises an upper breeding net and a lower breeding net, and the upper breeding net and the lower breeding net are connected;

[0014] The lower breeding net is a copper alloy net; the height of the lower breeding net is greater than half the depth of the sea water body, the mesh is a square mesh, and the side length of the square mesh is 2 to 6 cm;

[0015] The upper breeding net is a bulletproof net; the mesh of the upper breeding net is a square mesh, and the side length of the square mesh is 2 to 6 centimeters.

[0016] Preferably, the average size of the large yellow croaker fry is 450-500 grams per tail, and the sum of the body length and body width of the large yellow croaker fry is greater than 4 centimeters; the stocking density of the large yellow croaker is 800-1200 tails per mu;

[0017] The stocking period of the large yellow croaker fry is from May to July, and the large yellow croaker fry is transported to the fence net breeding facility platform for stocking by a live water vessel.

[0018] Preferably, the average specification of the three-tuberculate swimming crab seedlings is 70-80 grams per crab; the stocking density of the three-tuberculate swimming crabs is 400-600 per mu, and the male-female ratio is 2:8; the stocking period of the three-tuberculate swimming crab seedlings is July to August.

[0019] Preferably, the Swimming crab seedlings include Swimming crab seedlings obtained by culture in a pond;

[0020] Before the stocking of the swimming crab seedlings, the swimming crab seedlings obtained by cultivation in the pond are caught in the pond by fishing and transported to the fence net breeding facility platform for stocking; the transportation method of the swimming crab seedlings includes: transporting the swimming crab seedlings to the wharf nearest to the fence net breeding facility platform by land seafood transportation tools, and continuing to transport the swimming crab seedlings transported to the wharf to the fence net breeding facility platform by sea live water transportation tools.

[0021] Preferably, in the mixed culture process, large yellow croaker is fed with feed and swimming crab is fed with ice-fresh miscellaneous fish twice a day, and the feeding time is 5-6 o'clock and 17-18 o'clock every day; the feeding amount of swimming crab is 4%-6% of the weight of swimming crab, and the feeding amount of large yellow croaker is 8%-12% of the weight of large yellow croaker.

[0022] Preferably, the polyculture management includes water quality monitoring, disease prevention and control, and growth monitoring;

[0023] The water quality monitoring includes monitoring the dissolved oxygen, ammonia nitrogen and pH value of the aquaculture water; the dissolved oxygen content is ≥5 mg / L, the ammonia nitrogen content is ≤0.2 mg / L, and the pH value is 7.8-8.5;

[0024] The growth monitoring includes: measuring the growth of large yellow croaker and swimming crab every other month; if the growth difference of large yellow croaker and swimming crab between two consecutive monitorings is not significant, adjusting the feeding amount and feeding frequency of large yellow croaker and swimming crab.

[0025] Preferably, the large yellow croaker is captured from December of the year of stocking to April of the following year; the swimming crab is captured from late December of the year of stocking to March of the following year.

[0026] Beneficial effects:

[0027] The present invention provides a method for polyculture of large yellow croaker and swimming crab in sea areas. The present invention polycultures large yellow croaker fry and swimming crab fry in a fence net culture facility platform located in the sea area, and performs polyculture management until capture; the fence net culture facility platform is a fence net closed on all sides, including an external skeleton support structure and a culture net surrounding the external skeleton support structure; one end of the external skeleton support structure is inserted into the seabed, and the other end is exposed above the water surface; one end of the culture net is buried in the seabed in the vertical direction, and the depth of the mud is greater than 0.5 meters; the other end is exposed above the water surface, and the height is flush with the height of the external skeleton support structure exposed above the water surface. The polyculture method in sea areas has the following advantages:

[0028] (1) Higher space utilization: Yellow croaker and swimming crab live in different water layers and have similar feeding habits, so the aquaculture space in the sea can be fully utilized. However, the water in traditional pond aquaculture is usually shallow, making it difficult to achieve complete water stratification.

[0029] (2) Higher feed utilization rate: The feed that sinks to the bottom of the water and is not used by the yellow croaker can be used by the swimming crab, which increases the feed utilization rate and reduces feed waste.

[0030] (3) Reduce the deposition of nutrients on the seabed: The three-spotted swimming crab can flip over the bottom of the fence net, and the dirt on the seabed will enter the water body after being flipped over, forming a nutrient source for algae reproduction, which is beneficial to reduce the deposition of nutrients on the seabed.

[0031] (4) Disease prevention and control: The sick and dead individuals of yellow croaker can easily interfere with the spread of fish diseases to healthy yellow croakers. However, yellow croaker diseases cannot infect swimming crabs. Swimming crabs can eat the sick and dead individuals of yellow croaker that have entered the water layer where swimming crabs live, which is beneficial to controlling the spread of fish diseases in polyculture systems.

[0032] (5) Stronger ability to resist wind and waves: Fence net farming has fewer attachments on the net and less water flow resistance, thus greatly improving the ability to resist wind and waves.

[0033] (6) A more ecological aquaculture model: The fence net is an open aquaculture environment. Various small marine fish and benthic organisms can continuously enter the fence net and become natural bait for large yellow croaker and swimming crab, further reducing the amount of feed fed, thus realizing an ecological aquaculture form with better aquaculture benefits than the traditional single-culture model. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0035] Figure 1 The technical flow chart of the polyculture method of large yellow croaker and swimming crab in Example 1;

[0036] Figure 2 The following is the growth condition of the swimming crab (Panthera trituberculata) in the fence net in Example 1. DETAILED DESCRIPTION

[0037] The present invention provides a method for polyculture of large yellow croaker and swimming crab in sea area, comprising the following steps:

[0038] The large yellow croaker fry and the swimming crab fry are co-cultured in a fence net culture facility platform located in the sea area, and the co-culture management is carried out until they are captured;

[0039] The fence net breeding facility platform is a fence net closed on all sides, including an external skeleton support structure and a breeding net surrounding the external skeleton support structure;

[0040] One end of the external skeleton support structure is inserted into the seabed, and the other end is exposed above the water surface;

[0041] One end of the aquaculture net in the vertical direction is buried in the seabed, with a depth of more than 0.5 meters; the other end is exposed above the water surface, and the height is flush with the height of the external skeleton support structure exposed above the water surface.

[0042] The present invention first builds the fence net aquaculture facility platform. In the sea area, the present invention inserts one end of the external skeleton support structure into the seabed, and the other end is exposed above the water surface. As an embodiment, the material of the external skeleton support structure includes one or more of iron, cement, stainless steel and steel coated with anti-corrosion and anti-rust paint; as another embodiment, the material of the external skeleton support structure is iron, cement, stainless steel or steel coated with anti-corrosion and anti-rust paint; as another embodiment, the material of the external skeleton support structure is iron. As an embodiment, the external skeleton support structure is a columnar structure; as another embodiment, the columnar structure can be a circular columnar structure, a square columnar structure, a hexagonal columnar structure or an octagonal columnar structure; in a specific embodiment, the external skeleton support structure is an iron pipe pile. The present invention does not specifically limit the location of the external skeleton support structure, and it can be located in deep sea or shallow sea.

[0043] After the external skeleton support structure is set, as an embodiment, the present invention surrounds the external support structure with a breeding net to form a fence net closed on all sides. As an embodiment, one end of the breeding net in the vertical direction is buried in the seabed, and the depth of the breeding net in the mud is greater than 0.5 meters; the other end is exposed above the water surface, and the height is flush with the height of the external skeleton support structure exposed above the water surface. As an embodiment, the breeding net includes an upper breeding net and a lower breeding net, and the upper breeding net and the lower breeding net are connected. The advantage of the present invention that the breeding net is divided into upper and lower parts is that the upper breeding net has the function of convenient replacement and cleaning, and the lower breeding net includes a breeding net made of copper alloy, which has natural anti-parasitic ability and anti-biological adhesion ability; the connected upper breeding net and lower breeding net can prevent large yellow croaker and swimming crab from escaping. As an embodiment, the lower breeding net is a copper alloy net; the height of the lower breeding net is greater than half the depth of the water body in the sea area, and the setting of this height has a better anti-escape effect and better wind and wave resistance and stability, and the mesh is a square mesh, and the side length of the square mesh is 2 to 6 cm; as another embodiment, the side length of the square mesh is 4 cm. As an embodiment, the upper breeding net is a bulletproof net; the mesh of the upper breeding net is a square mesh, and the side length of the square mesh is 2 to 6 cm; as another embodiment, the side length of the square mesh is 4 cm. The copper alloy net of the present invention has natural anti-parasite and anti-attachment capabilities. The fence net breeding based on the copper alloy net has less attachments on the net and less water flow resistance, thereby greatly improving the wind and wave resistance. The mesh of the breeding net of the present invention is set according to the specifications of the large yellow croaker seedlings and three-spotted swimming crab seedlings to ensure that the large yellow croaker seedlings and three-spotted swimming crab seedlings initially released cannot escape.

[0044] After the fence net culture facility platform is built, the present invention releases large yellow croaker fry and swimming crab fry into the fence net culture facility platform for mixed culture, and performs mixed culture management until harvest.

[0045] As an embodiment, the stocking period of the large yellow croaker seedlings of the present invention is from May to July, and the large yellow croaker seedlings are transported to the fence net breeding facility platform for stocking by a live water boat; the large yellow croaker seedlings transported by a live water boat can ensure that the survival rate of the large yellow croaker fish is above 95%. As an embodiment, the average specification of the large yellow croaker seedlings of the present invention is 450 to 500 grams per tail, and the sum of the body length and body width of the large yellow croaker seedlings is greater than 4 cm; the stocking density of the large yellow croaker is 800 to 1200 tails per mu. As an embodiment, the present invention can improve the survival rate of large yellow croaker breeding through food habit domestication, feed feeding or disease prevention and control to ensure the survival rate of the large yellow croaker seedlings when stocked.

[0046] As an embodiment, the stocking period of the swimming crab seedlings of the present invention is July to August. As an embodiment, the average specification of the swimming crab seedlings of the present invention is 70 to 80 grams per crab; as another embodiment, the average specification of the swimming crab seedlings of the present invention is 75 grams per crab; the swimming crab seedlings of the specifications can ensure that the body width and height of the swimming crab are larger than the mesh of the fence net, achieving the function of preventing escape. As an embodiment, the stocking density of the swimming crabs of the present invention is 400 to 600 per mu, as another embodiment, the stocking density of the swimming crabs of the present invention is 500 per mu; as an embodiment, the male-female ratio of the swimming crabs of the present invention is 2:8; the male-female ratio has the advantage of satisfying the mating ratio of male and female crabs.

[0047] As an embodiment, the three-tuberculate swimming crab seedlings of the present invention are three-tuberculate swimming crab seedlings obtained by cultivation in a pond. As an embodiment, the method for cultivating three-tuberculate swimming crabs in a pond comprises: cultivating three-tuberculate swimming crab seedlings in a pond to obtain the three-tuberculate swimming crab seedlings. As an embodiment, the three-tuberculate swimming crab seedlings can be varieties with advantages in production performance and disease resistance, such as Keyong No. 1 or Ningxiang No. 1. As an implementation method, during the cultivation process, the three-tuberculate swimming crab seedlings are fed with ice-fresh miscellaneous fish, and the feeding amount is 8% to 12% of the body weight of the three-tuberculate swimming crab seedlings; as another embodiment, the feeding amount is 10% of the body weight of the three-tuberculate swimming crab seedlings, and the feeding strategy can be adjusted according to the feeding situation of the three-tuberculate swimming crab seedlings to ensure that the three-tuberculate swimming crab seedlings grow without excessive feeding causing water quality deterioration. As an embodiment, a pond with clean water and rich in natural bait is selected to ensure good water flow and stable water quality; as another embodiment, the bottom of the pond has a silt layer to provide an environment for the swimming crab to live and forage. As an embodiment, the present invention sets the stocking density of swimming crab fry according to the area and water quality of the pond; as another embodiment, the stocking density of the swimming crab is 24,000 to 27,000 swimming crab fry (developed to the first stage of juvenile crab) with a shell width of 1.5 cm per mu, or 1,000 to 1,500 swimming crab fry of 50 grams per mu. The stocking density described in the present invention can avoid the competition for food caused by the overcrowding of the swimming crab fry.

[0048] As an embodiment, before the stocking of the Swimming Crab Seedlings of the Three-Turtled Swimming Crab, the three-tubertled swimming crab seedlings obtained by cultivation in the pond are caught in the pond by fishing, and transported to the fence net aquaculture facility platform for stocking; as an embodiment, the fishing is carried out by fishing without a hook, and the bait is tied with a rope; the fishing method can avoid the damage to the crab caused by fishing. As an embodiment, the present invention uses rubber bands to tie the crab legs of the crabs obtained by fishing to avoid death caused by fighting between different individuals. As an embodiment, the transportation method of the three-tubertled swimming crab seedlings includes: transporting the three-tubertled swimming crab seedlings to the nearest wharf to the fence net aquaculture facility platform by land seafood transportation tools, and continuing to transport the three-tubertled swimming crab seedlings transported to the wharf to the fence net aquaculture facility platform by sea live water transportation tools; in a specific embodiment, the three-tubertled swimming crab seedlings are transported by seafood transportation vehicles and speedboats.

[0049] As an embodiment, in the mixed culture process, large yellow croaker is fed with feed and swimming crab is fed with ice-fresh fish twice a day, and the feeding time is 5-6 o'clock and 17-18 o'clock every day; the feeding amount of swimming crab is 4%-6% of the weight of swimming crab, and the feeding amount of large yellow croaker is 8%-12% of the weight of large yellow croaker. As another embodiment, the feeding amount of swimming crab is 5% of the weight of swimming crab, and the feeding amount of large yellow croaker is 10% of the weight of large yellow croaker. The present invention has no special restrictions on the source and specifications of the feed and ice-fresh fish, and the feed and ice-fresh fish suitable for large yellow croaker from conventional sources in the field can be used.

[0050] As an embodiment, the polyculture management of the present invention includes water quality monitoring, disease prevention and control, and growth monitoring. As an embodiment, the water quality monitoring includes monitoring the dissolved oxygen, ammonia nitrogen and pH value of the aquaculture water; the dissolved oxygen content is ≥5 mg / L, the ammonia nitrogen content is ≤0.2 mg / L, and the pH value is 7.8-8.5. As another embodiment, the dissolved oxygen content can be maintained at 6-8 mg / L; the ammonia nitrogen content can be maintained at 0-0.1 mg / L. As an embodiment, the growth monitoring is: measuring the growth of large yellow croaker and swimming crab every other month; if the growth difference of large yellow croaker and swimming crab in two adjacent monitorings is not significant, adjust the feeding amount and feeding frequency of large yellow croaker and swimming crab. As an embodiment, the disease prevention and control can be to observe the health status of large yellow croaker and swimming crab, deal with diseases in time, and reduce losses. The present invention does not specifically limit the specific process in the disease prevention and control, and the process of conventional disease prevention and control in this field can be used.

[0051] As an embodiment, the large yellow croaker is captured from December of the year of stocking to April of the following year; as another embodiment, the large yellow croaker is captured in January of the following year; during the capture period of the large yellow croaker, the large yellow croaker has relatively few growth and reproduction activities and is easier to catch. As an embodiment, the large yellow croaker is captured by trawling. As an embodiment, the three-spotted swimming crab is captured from late December of the year of stocking to March of the following year. As an embodiment, the three-spotted swimming crab is captured by ground trap fishing.

[0052] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0053] Example 1

[0054] A method for polyculture of large yellow croaker and swimming crab, the technical flow chart is as follows Figure 1 As shown, the steps are as follows:

[0055] 1. Construction of the pillar type copper alloy fence breeding facility platform

[0056] The external skeleton support structure of the aquaculture platform is composed of iron pipe piles, which are driven directly into the seabed by a pile driver. The depth of the iron pipe piles is greater than 10 meters, and the part of the end of the iron pipe piles (at the highest water level) exposed above the water surface is not less than 8 meters. The net is divided into two parts, the upper and lower parts must be connected. The lower part of the aquaculture net is surrounded by a copper alloy net with a square mesh and a side length of 4 cm. The net height is greater than half the water depth and the depth of the mud is greater than 0.5 meters; the upper part is connected to a bulletproof net with a mesh of 4 cm. The height of the bulletproof net (at the highest water level) exposed above the water surface is flush with the end of the iron pipe pile.

[0057] The reason why the lower part of the breeding net is surrounded by copper alloy net is that copper alloy net has low biological adhesion ability, which can reduce the water flow obstruction caused by biological adhesion. At the same time, copper alloy net has the function of preventing animal diseases. The upper part is connected to the bulletproof net because the corresponding net is easy to replace and clean. When stocking fish and crab fry, the fish and crab fry are directly placed underwater at the top of the inner part of the bulletproof net, close to the water surface.

[0058] 2. Large yellow croaker farming with fence net

[0059] In June, select high-quality yellow croaker fry (the average size of the fish is 450g / fish, and the stocking density of yellow croaker is 1,000 / mu), choose weather with small winds and waves and suitable temperature (15 degrees -20 degrees), use live water boats to transport the yellow croaker fry to the fence net for stocking, and the transportation survival rate is over 95%. The area of ​​the cross-section of the released yellow croaker fry perpendicular to the body axis must be larger than the mesh of the fence net (body length + height is greater than 8 cm).

[0060] 3. Pond cultivation of swimming crab

[0061] Select healthy, vigorous, high-quality swimming crab varieties, Crab Seedlings of Keyong No. 1, to ensure that they come from unpolluted waters to reduce the risk of disease. Cultivate swimming crab seedlings in ponds with clean water and rich natural bait. There should be a suitable mud and sand layer at the bottom of the pond to provide an environment for crabs to live and forage. The breeding density of swimming crab seedlings is: 24,000 to 27,000 crab seedlings of 1.5 cm in size per mu, or 1,000 to 1,500 large-sized crab seedlings of 50 grams. Feed frozen fish in the pond to cultivate large-sized swimming crabs (the size of swimming crabs should not be smaller than the mesh of the fence net). The feeding amount is determined according to 10% of the body weight of the swimming crabs. Reasonably control the amount of feed to prevent excessive feeding from causing water quality deterioration. Feed regularly, 1-2 times a day, and observe the feeding situation of the crabs so as to adjust the feeding strategy in time.

[0062] 4. Large-sized swimming crabs transported by land and sea

[0063] Before transportation, the three-spotted swimming crabs are caught by fishing (fishing without hooks, directly tying the bait with a rope for fishing). The captured crabs are tied firmly with rubber bands on their left and right claws (to prevent mutual attack) to avoid fighting between different individuals and death. Fishing is carried out in the early morning or evening when the temperature is relatively low.

[0064] In August, seafood transport vehicles (live water vehicles) were used to transport large-sized swimming crabs from the breeding ponds to the nearest dock of the fence. During land transportation, the crabs were stacked and placed in cylindrical polyethylene plastic baskets (radius 25cm, height 20cm) with rubber bands tied to their claws. Each basket contained 50 crabs. The plastic baskets were then placed in white round buckets for transportation. Six plastic baskets were placed in each bucket. The plastic baskets were submerged in seawater and an oxygen pump was placed in the bucket. Ice cubes were placed in the live water vehicle to control the temperature at 25℃. When transporting, the transport boxes should be protected from the sun and rain, kept moist, ventilated and cool. Frequent inspections should be carried out during transportation, and countermeasures should be taken in time if problems are found, such as timely removal of dead seedlings, feces, leftover bait and other dirt to reduce the oxygen consumption of these dirt during the decomposition process. At the same time, water changes, water sprinkling and oxygenation should be done well. The transportation time should be controlled within 4 hours.

[0065] The survival rate of swimming crabs during transportation is enhanced by adding probiotics into the water in which they are transported (probiotics are a mixed bacteria, generally including photosynthetic bacteria, yeast and lactic acid bacteria. This embodiment uses probiotics for dolphin fish, koi digestion and absorption aid, lactic acid bacteria EM bacteria, probiotics EM bacteria for ornamental fish (specification is 1L) (JD platform product number: 10042004736602), and the amount of probiotics added is 18 ml / cubic water).

[0066] Use speedboat to transport the swimming crabs to the fence net. Choose a night with lower temperature for transportation, and choose a dock with better water quality and close to the fence net. Move the plastic baskets containing swimming crabs into a black water tank of about 1 cubic meter. Put 7-8 round frames in one water tank. Use a water pump to directly extract seawater in the port and use a portable aerator pump to increase oxygen. The shipping time is controlled within 2 hours. The seedlings are released at 1 to 2 o'clock in the morning when the temperature is low. The ratio of male to female swimming crabs in the release area is controlled at 2:8. The density of the release of swimming crabs is 500 per mu, and the average size is 78 grams per crab. After long-distance transportation, the seedlings are weak and not adapted to the local climatic conditions. First, place them next to the fence for 3-5 minutes to adapt to the local environment. Then take the seawater from the fence area and pour a small amount of water on the seedlings 2-3 times to let them adapt to the water temperature in the sea area. Cut off the rubber band tied to the crab body with scissors and remove the poor quality ones.

[0067] 5. Multi-trophic-level co-culture of large yellow croaker and swimming crab

[0068] Swimming crabs were fed with iced fish at 5% of their body weight, and yellow croakers were fed with compound feed (Rongyu Yellow Croaker Compound Feed 988 produced by Fujian Dachangsheng Feed Co., Ltd.) at 10% of their body weight to ensure that they get enough nutrition and prevent eutrophication of the water body caused by overfeeding. They were fed twice a day, in the morning before dawn (5-6 o'clock) or at dusk (17-18 o'clock), and the corresponding bait was evenly thrown to various parts of the fence net culture facility platform during feeding.

[0069] In the management of mixed culture, it is necessary to do a good job of (1) water quality monitoring: regularly monitor water quality, maintain the dissolved oxygen content at 6-8 mg / L; ammonia nitrogen concentration should be controlled at 0-0.1 mg / L; pH value should be maintained between 7.8 and 8.5 to ensure a suitable growth environment. (2) Disease prevention and control: observe the health status of fish and crabs, deal with diseases in a timely manner, and reduce losses. (3) Growth monitoring: measure the growth of the two species every month to adjust the feeding strategy and breeding management methods. Specifically: compare the growth curve of the three-spotted swimming crab (the corresponding relationship between age and body length, weight and other data) obtained from the farm waters. If the growth difference is not significant, you can consider increasing the feeding amount and feeding frequency.

[0070] 6. Fishing for large yellow croaker and swimming crab

[0071] Large yellow croakers are caught in January. Swimming crabs are caught using ground traps from late December to March of the following year. The ground traps are evenly placed in the fence net the day before the catching. After the catching of swimming crabs, the left and right claws are tied firmly with rubber bands to prevent fighting between different individuals and cause death.

[0072] 7. Results Statistics

[0073] 7.1 According to statistics, the average size of the large yellow croaker farmed in the fence nets was 450 grams per fish when they were put into the fence nets in June. They were caught in January of the following year, and the survival rate was 86%, with an average size of 600 grams per fish.

[0074] The average size of the three-tuberculate swimming crabs cultured in the fence net was 78 grams per crab when they were put into the fence net in August. The production was measured in October and the survival rate was about 70%, with an average size of 147 grams per crab, as shown in Table 1 and Figure 2 As shown. Among them, there was no significant difference between the stocking stage and the first month of stocking (P>0.05), which may be due to factors such as transportation and environmental changes that caused the slow growth of the three-spotted swimming crab. One month after stocking, 21 crabs were measured, and the maximum weight was 145.4g. Compared with the first month after stocking, the weight increase in the second month after stocking was significant (P<0.05). It can be seen that the three-spotted swimming crab has adapted to the existing breeding environment and has a good growth effect. Two months after stocking, the maximum weight of the 26 crabs measured was 243.6g. Overall, compared with the stocking stage, the three-spotted swimming crab grew better two months after stocking and has reached the market specifications. The growth of large yellow croaker is also very rapid. In the production measurement carried out in November, the average weight reached 663g (Table 2).

[0075] Table 1 Growth status of swimming crab in the fence net

[0076] project Seedling time (g) Cultivation 1 month (g) 2 months of breeding (g) Average specifications 78 92 147 Standard Deviation 27 27 51

[0077] Table 2 Weight changes of large yellow croaker in polyculture mode

[0078] - Average weight at stocking (g / tail) Average body weight at birth in November (g / tail) Weight gain rate (%) Large yellow croaker 450 663 147

[0079] The average price of yellow croaker cultured in fence nets is 200 yuan / catty, which is about 10 times that of yellow croaker cultured in ordinary ponds (average price is 20 yuan / catty). At the same time, the average price of swimming crabs cultured in fence nets is 300 yuan / catty, which is about 6 times that of swimming crabs cultured in ordinary ponds (average price is 50 yuan / catty). The market price is considerable. The mixed farming of swimming crabs and yellow croakers has a more significant input-output ratio than single farming, and the farming benefits are better than the traditional single farming model.

[0080] 7.2 During the land-sea relay transportation of swimming crabs, scientific temperature control, humidity regulation and appropriate transportation speed, combined with timely monitoring and emergency measures, successfully avoided the common transportation loss problems in traditional transportation modes and ensured the health and vitality of swimming crabs. The successful implementation of this transportation mode has enabled the swimming crab "Keyong No. 1" to maintain a high survival rate during long-distance transportation.

[0081] The experimental results show that after the sea-land relay transportation, 2,500 survived the first transportation, with a survival rate of 96%; 3,300 survived the second transportation, with a survival rate of 94%; and 1,685 survived the third transportation, with a survival rate of 98%. The average survival rate is 96%.

[0082] According to the results of the multi-trophic level breeding experiment in the fence, 8,400 yellow croakers died during the breeding period, and the survival rate was 83.2%. In order to track the growth trend of yellow croakers, two batches of yellow croakers were caught on site on November 28, 2024, with 30 fish in each batch, a total of 60 fish, with a total weight of 10.61kg and an average size of 0.663kg / fish.

[0083] 8. Economic benefit analysis under monoculture and polyculture models

[0084] The economic benefit analysis of different breeding modes is shown in Table 3. The breeding mode of large yellow croaker monoculture is based on the method of large yellow croaker and swimming crab polyculture in Example 1 of the present invention (wherein the part and process of swimming crab breeding are deleted).

[0085] Table 3 Comparison of economic benefits under monoculture and polyculture (total aquaculture water area is 16.5 mu)

[0086]

[0087] Note: “—” indicates no data, * indicates that part of the feed of yellow croaker can be utilized by swimming crab, so mixed culture can reduce the feeding amount of swimming crab.

[0088] There is a large gap in the costs of different breeding modes, and the main expenses are site, bait, labor and seedling fees. In terms of income, the total income and net profit of the mixed breeding group are higher than those of the single breeding group. Economic benefits Under the single breeding mode, due to the lack of symbiotic advantages of complementary species, it may lead to inefficient resource utilization and increased risk of diseases, thereby affecting economic benefits. In addition, the single breeding mode has a large impact on the environment and may require more water quality management and disease prevention and control investment. Under the multi-trophic level breeding mode (the mode in Example 1 of the present invention), in addition to large yellow croaker, there is also a source of income for swimming crabs with three tubercles. In the aquaculture industry, multi-species mixed breeding technology has been widely used. The mixed breeding system with multiple species can not only improve the recycling of resources to maintain the stability of organisms and the environment, but also has better economic benefits and sustainability. In terms of bait, compared with single breeding, the three-tuberculate swimming crab can use the residual bait when breeding large yellow croaker, which reduces the waste of bait and improves the utilization rate. In terms of disease control, swimming crabs with three tubercles can eat large yellow croakers that die and sink to the bottom of the water to prevent the dead fish from further rotting at the bottom of the water and reduce the spread of diseases. The quality of multi-trophic level farming model may be better than that of single farming model, and may have higher competitiveness and selling price in the market.

[0089] In summary, the multi-trophic level farming model has obvious advantages in economic benefits, can bring higher net profits and faster returns on investment to farmers, and is also in line with the trend of sustainable development. Although the initial investment of the single farming model is lower, in the long run, the economic benefits and environmental impact may not be as good as the multi-trophic level farming model.

[0090] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for polyculture of large yellow croaker and swimming crab in sea area, characterized in that: The steps include: The large yellow croaker fry and the swimming crab fry are co-cultured in a fence net culture facility platform located in the sea area, and the co-culture management is carried out until they are captured; The fence net breeding facility platform is a fence net closed on all sides, including an external skeleton support structure and a breeding net surrounding the external skeleton support structure; One end of the external skeleton support structure is inserted into the seabed, and the other end is exposed above the water surface; One end of the aquaculture net in the vertical direction is buried in the seabed, with a depth of more than 0.5 meters; the other end is exposed above the water surface, and the height is flush with the height of the external skeleton support structure exposed above the water surface.

2. The marine polyculture method according to claim 1, characterized in that: The material of the external skeleton support structure includes one or more of iron, cement, stainless steel and steel coated with anti-corrosion and anti-rust paint.

3. The marine polyculture method according to claim 1 or 2, characterized in that: The external skeleton support structure is a columnar structure.

4. The marine polyculture method according to claim 1, characterized in that: The breeding net comprises an upper breeding net and a lower breeding net, and the upper breeding net and the lower breeding net are connected; The lower breeding net is a copper alloy net; the height of the lower breeding net is greater than half the depth of the sea water body, the mesh is a square mesh, and the side length of the square mesh is 2 to 6 centimeters; The upper breeding net is a bulletproof net; the mesh of the upper breeding net is a square mesh, and the side length of the square mesh is 2 to 6 centimeters.

5. The marine polyculture method according to claim 1, characterized in that: The average size of the large yellow croaker fry is 450-500 grams per tail, and the sum of the body length and body width of the large yellow croaker fry is greater than 4 centimeters; the stocking density of the large yellow croaker is 800-1200 tails per mu; The stocking period of the large yellow croaker fry is from May to July, and the large yellow croaker fry is transported to the fence net breeding facility platform for stocking by a live water vessel.

6. The marine polyculture method according to claim 1, characterized in that: The average specification of the three-tuberculate swimming crab seedlings is 70-80 grams per crab; the stocking density of the three-tuberculate swimming crabs is 400-600 per mu, and the female-male ratio is 2:8; the stocking period of the three-tuberculate swimming crab seedlings is July to August.

7. The marine polyculture method according to claim 6, characterized in that: The three-tuberculate swimming crab seedlings include three-tuberculate swimming crab seedlings obtained by cultivation in a pond; Before the swimming crab fry is released, the swimming crab fry obtained by culture in the pond is caught in the pond by fishing, and transported to the fence net culture facility platform for release; The transportation method of the swimming crab seedlings includes: transporting the swimming crab seedlings to the wharf closest to the fence net breeding facility platform by land seafood transportation tools, and continuing to transport the swimming crab seedlings transported to the wharf to the fence net breeding facility platform by sea live water transportation tools.

8. The marine polyculture method according to claim 1, characterized in that: During the mixed culture process, large yellow croakers are fed with feed and swimming crabs are fed with ice-fresh miscellaneous fishes twice a day, and the feeding time is 5-6 o'clock and 17-18 o'clock every day; the feeding amount of the swimming crabs is 4%-6% of the weight of the swimming crabs, and the feeding amount of the large yellow croaker is 8%-12% of the weight of the large yellow croaker.

9. The marine polyculture method according to claim 1, characterized in that: The polyculture management includes water quality monitoring, disease prevention and control, and growth monitoring; The water quality monitoring includes monitoring the dissolved oxygen, ammonia nitrogen and pH value of the aquaculture water; the dissolved oxygen content is ≥5 mg / L, the ammonia nitrogen content is ≤0.2 mg / L, and the pH value is 7.8-8.5; The growth monitoring includes: measuring the growth of large yellow croaker and swimming crab every other month; if the growth difference of large yellow croaker and swimming crab between two consecutive monitorings is not significant, adjusting the feeding amount and feeding frequency of large yellow croaker and swimming crab.

10. The marine polyculture method according to claim 1, characterized in that: The capture time of the large yellow croaker is from December of the year of stocking to April of the following year; the capture time of the swimming crab is from late December of the year of stocking to March of the following year.

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