A breeding method suitable for high-density ecological breeding of american shad

Abstract

The application discloses a breeding method suitable for high-density ecological breeding of American shad, which comprises the following steps: using a purse seine to establish a purse seine breeding area as a fry centralized domestication area in a pond, adopting high-density breeding, and having an oxygenation device on the purse seine to oxygenate the pond; in the first growth stage of the shad, with the growth of the fry, the centralized domestication area is gradually expanded by gradually changing the purse seine; when the first growth stage is completed, the shad is caught; when the shad is caught to a low-density breeding degree, the shad is stopped from being caught, the purse seine is removed, and the shad enters the second growth stage; the feeding bait is changed, and the remaining shad is fed with fattening bait; when the second growth stage is completed, the remaining shad is caught completely. Through the continuous expansion of the purse seine breeding area, the damage of the shad caused by the centralized domestication and the shad being divided into ponds is avoided; a gas wall is formed in the bottom and upper areas of the purse seine, the fish school is isolated by the gas wall, direct contact between the fish school and the fishing net is avoided, and the shad is prevented from being scratched or injured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aquaculture, in particular to a breeding method suitable for high-density ecological breeding of American shad. BACKGROUND

[0002] American shad (hereinafter referred to as shad) has high requirements for water quality and likes to live in fresh water with a water temperature of 16-30℃, so it is usually necessary to build a greenhouse to control the density and adjust the water quality to ensure safe overwintering and oversummering.

[0003] Traditional shad breeding takes 16-18 months to reach a marketable small size of about 0.8kg-1kg, the breeding cycle is long, and the risk is high. The traditional greenhouse is a steel structure with a cost of 150-200 thousand yuan per mu, has many vertical columns in the pond, has high investment, high threshold, and difficult fishing, and is extremely unfavorable for the expansion of the shad industry. The traditional shad breeding pond does not have a bottom sewage device and cannot regularly suck sewage, so the residual feed and feces brought by long-term breeding and feeding dissolve in the breeding water under the decomposition of microorganisms in the water. The water quality self-cleaning capacity is sufficient during the fry period, but the fish body becomes larger in the following year, and the feeding increases, especially in summer, which exceeds the self-purification load of the water body, resulting in excessive accumulation of harmful substances such as ammonia nitrogen and nitrite, high temperature accelerates the deterioration of water quality, and the risk of pond explosion occurs, so the overall breeding density of shad is not high, and the yield is limited. And shad belongs to a group of fish, and in the past, the density of the breeding tank was convenient for domestication, but the shad had a strong stress response and a high damage rate during the later separation of fry. The relative area of the fry pond is relatively large, and the young fish are not concentrated for domestication or are not domesticated properly, so the fish group moves irregularly, the size difference is large, and therefore the survival rate is very low.

[0004] The traditional shad breeding cycle is long, the effect is slow, the cost of the traditional greenhouse is high, and it cannot be popularized and popularized, the traditional breeding lacks effective in-situ purification needs, the breeding density is limited, and the yield is limited, and the shad fry needs to be managed in a concentrated manner in the early stage, and the damage is large in the later stage, and the survival rate is low. SUMMARY

[0005] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide a breeding method suitable for high-density ecological breeding of American shad, which can greatly improve the yield of shad, reduce the breeding cost, improve the breeding income, make the breeding risk controllable, and promote the development of the shad industry.

[0006] Technical scheme: In order to achieve the above-mentioned purpose, a breeding method suitable for high-density ecological breeding of American shad, comprising the following steps:

[0007] S1: using a purse seine to establish a purse seine breeding area as a fry concentrated domestication area in a pond, and adopting high-density breeding, the purse seine has an oxygenation device, and the pond is oxygenated in the form of aeration in the subsequent steps;

[0008] S2: in the first growth stage of the fish, with the growth of the fry, the concentration area is gradually expanded by gradually changing the net;

[0009] S3: when the first growth stage of the fish is completed, the first catch of the fish is carried out;

[0010] S4: when the first catch of the fish is caught to a low-density breeding degree, the fish is stopped and the net is removed, and the fish enters the second growth stage;

[0011] S5: in the second growth stage of the fish, the remaining fish is fattened by changing the bait;

[0012] S6: when the second growth stage of the fish is completed, the remaining fish is caught.

[0013] Further, the first growth stage of the fish in the S2 step includes at least five size growth stages; when the fish enters the second size growth stage from the first size growth stage, the net breeding area of the fish is expanded once; the net breeding area is expanded once every time the fish enters the next size growth stage.

[0014] Further, the first size growth stage and the second size growth stage use the initial net, the mesh of which is set so that the fish cannot swim out of the net breeding area, and the pond outside the net breeding area is used to breed shrimps, which cannot enter the net breeding area.

[0015] Further, when the fish enters the third size growth stage, the size of the fish is significantly larger than that of the shrimps; the mesh of the net is changed while the net breeding area is expanded, so that the fish in the third size growth stage cannot swim out of the net breeding area, and the shrimps can enter the net breeding area; the mesh of the net used in the subsequent size growth stages is the mesh of the net used in the third size growth stage; when the fish enters the last size growth stage, the first growth stage of the fish is completed.

[0016] Further, when the fish enters the third size growth stage, the net breeding area is expanded to occupy part of the pond, so that the breeding area of the shrimps is reduced.

[0017] Further, the net breeding area is expanded by increasing the number of nets; each time the net breeding area is expanded, the net breeding area for the next size growth stage is set, and then the original net breeding area is removed.

[0018] Further, the net includes a bottom frame and an upper frame; the bottom frame is provided with an aeration pipe along the length direction, and the aeration pipe is provided with air outlets along the length direction; the air outlets of the aeration pipe continuously emit bubbles upward.

[0019] Further, the aeration pipe on the bottom of the net continuously emits bubbles, forming a bubble wall on one side of the bottom to the upper area of the net, avoiding the contact between the fish and the net.

[0020] Further, the bubbles emitted by the bottom of the net continuously float upwards, forming a rapid upward flow away from the side of the net, and the fish swim upwards under the action of the flow. Since the bubbles break when they rise to the water surface, the sound produced by the breaking of the bubbles drives the fish away. At the same time, the water at the upper part of the net breeding area flows towards the center of the net breeding area due to the rapid upward flow below. The flow at the upper part of the net breeding area drives the fish away from the net.

[0021] Beneficial effects: The ecological breeding method of the present application is suitable for high-density ecological breeding of American salmon. The in-situ purification equipment, plant floating bed, shrimps and beneficial microorganisms in the fish pond work together to achieve in-situ purification of the water quality in the salmon pond, reduce the incidence of salmon disease, and effectively promote the ecological and healthy breeding of salmon. Salmon feces are natural feed for shrimps, and breeding shrimps can clean up salmon excrement, reducing the cleaning of the dirty bottom of the pond. At the same time, the bred shrimps can also be captured and sold.

[0022] By continuously expanding the net breeding area, the damage to the salmon caused by dividing the pool after concentrated domestication of the salmon is avoided. Aeration pipes are arranged on the bottom and side of the net, and a bubble wall is formed on the bottom and upper area of the net, so that the net is not easy to be blocked by algae and the water exchange is smooth. At the same time, the fish school is isolated by the bubble wall, avoiding direct contact between the fish school and the fishing net, thereby avoiding scratching off scales or being injured. BRIEF DESCRIPTION OF DRAWINGS

[0023] ATTACHED Figure 1 Schematic diagram of the net in the net breeding area;

[0024] ATTACHED Figure 2 Schematic diagram of the net;

[0025] ATTACHED Figure 3 Schematic diagram of the expansion of the net in the pond;

[0026] ATTACHED Figure 4 Schematic diagram of the longitudinal main beam;

[0027] ATTACHED Figure 5 Schematic diagram of the lateral hoop beam;

[0028] ATTACHED Figure 6 Schematic diagram of the longitudinal hoop beam. DETAILED DESCRIPTION

[0029] The present application will be further described below in conjunction with the drawings.

[0030] A breeding method suitable for high-density ecological breeding of American shad, comprising the following steps:

[0031] S1: Establish a net pen breeding area 2 as a fry centralized domestication area in the pond using a purse seine 1, adopt high-density breeding, the purse seine 1 is provided with an oxygenation device, and the pond is oxygenated in the form of aeration in subsequent steps;

[0032] S2: In the first growth stage of the shad, as the fry grows, gradually change the purse seine 1 to gradually expand the centralized domestication area;

[0033] S3: When the first growth stage of the shad is completed, the first capture of the shad is carried out;

[0034] S4: When the first capture of the shad reaches a low-density breeding level, stop capturing the shad, remove the purse seine 1, and the shad enters the second growth stage;

[0035] S5: In the second growth stage of the shad, change the bait feeding, and feed the remaining shad with fattening bait;

[0036] S6: When the second growth stage of the shad is completed, all the remaining shad are captured.

[0037] In the S1 step, the high-density breeding of the shad can reach a high density of 4000-4500 tails per mu, the purse seine breeding area 2 is established in accordance with the habit of the shad's lifelong migration without stopping, and the initial purse seine breeding area 2 occupies 1 / 10 of the pond area.

[0038] A composite modular new oxygenation mode composed of conventional bottom oxygenation, liquid oxygen and gas water oxygenation is set; according to the gas output of 150 cubic meters of oxygen per hour per 2.5 mu of the pond, the oxygen content in the pond is ensured to be in an oxygen-rich state; a 4.8 cubic meter liquid oxygen tank is added as an emergency oxygenation supplement to maintain the dissolved oxygen in the pond not less than 5 mg / L after the water temperature rises in the second spring.

[0039] Two gas water devices are set at any diagonal water depth of 3 meters in the pond, the gas water device is set in the pond, the water layer height of the gas water device is set to 0.5-1.5 meters underwater, and the water layer is the swimming water layer of the shad; the gas water device changes the previous oxygenation mode of shad breeding, and the external oxygen directly reaches the swimming water layer of the shad, artificially creates an oxygen-rich layer of water, meets the demand of the shad's rapid swimming to make the water flow through the gill filaments to filter oxygen; at the same time, the thrust brought by the gas water device promotes the water flow to be consistent with the swimming direction of the shad, reduces the swimming resistance of the shad, reduces the energy consumption of the shad, promotes the rapid growth of the shad, and shortens the conventional breeding period of 16-18 months to 15-17 months.

[0040] The power source of the gas water is a 4kw Roots blower fixed on the shore.

[0041] The enclosure 1 includes a bottom line 11 and a top line 12; the bottom line 11 of the enclosure 1 is provided with aeration pipes along its length, and the aeration pipes are provided with air outlets along their length; air bubbles continuously emerge from the air outlets of the aeration pipes; gas is introduced into the aeration pipes through a Roots blower.

[0042] The enclosure net 1 includes a side line with aeration pipes along its length, and a bottom line 11 consisting of densely packed iron weights to increase the contact area with the pool bottom and walls.

[0043] The aeration pipe on the bottom line 11 of the enclosure net 1 continuously emits bubbles, forming an air wall of bubbles on the side of the enclosure net 1 where there are shad from the bottom line 11 to the top line 12, thus preventing the shad from touching the enclosure net 1.

[0044] The bubbles emerging from the bottom line 11 continuously rise to the surface, creating a rapid upward water flow on the side of the air wall away from the enclosure net. The shad swims upward under the influence of the water flow. As the bubbles rise to the surface and burst, they produce a sound that drives the shad away. When the shad approaches the enclosure net 1, the rising water flow causes the shad to swim upward. When the shad reaches the surface, the bubbles on the surface burst, producing a sound that drives the shad away from the top line 12 of the enclosure net 1.

[0045] As attached Figure 1 As shown, at the same time, due to the rapidly rising water flow below, the water in the upper part of the net enclosure aquaculture area 2 flows towards the center of the net enclosure aquaculture area 2; the water flow in the upper part of the net enclosure aquaculture area 2 drives the shad away from the net enclosure 1.

[0046] The first growth stage of the shad in step S2 includes at least five body size growth stages; when the shad enters the second body size growth stage from the first body size growth stage, the net enclosure farming area 2 of the shad farming expands once; each time the shad enters the next body size growth stage, the net enclosure farming area 2 expands once.

[0047] Starting in June, the area of ​​the enclosure is expanded by 1 / 10 of the pond area every 60 days. By changing the enclosure, the area of ​​the aquaculture water is controlled, the density of shad is increased, and the shad form a circumferential group, thereby avoiding the damage caused by later separation into different ponds.

[0048] The enclosure aquaculture area 2 is expanded by increasing the number of enclosures 1. Each time the enclosure aquaculture area 2 is expanded, the enclosure aquaculture area 2 for the next growth stage is set up, and then the enclosures 1 of the original enclosure aquaculture area 2 are removed.

[0049] The first and second body growth stages use the initial net 1, which is set to a mesh size that prevents the ayu from swimming out of the net culture area 2, and the prawns are cultured in the pond outside the net culture area 2, which the prawns cannot enter.

[0050] When the ayu enters the third body growth stage, the ayu is significantly larger than the prawns; the net culture area 2 is expanded while the mesh size of the net is changed, so that the ayu in the third body growth stage cannot swim out of the net culture area 2, and the prawns can enter the net culture area 2; the mesh size of the net used in the subsequent body growth stages is the mesh size of the net used in the third body growth stage; when the ayu enters the third body growth stage, the net culture area 2 is expanded to occupy a portion of the area of the pond, so that the culture area of the prawns is reduced.

[0051] When the ayu enters the third body growth stage, the net culture area 2 occupies 1 / 3 of the area of the pond, and the mesh size of the net is changed from 5 meshes to 1 mesh to facilitate water exchange; when the ayu enters the third body growth stage, the net culture area 2 is continuously expanded to occupy a larger area of the pond, which encroaches on the culture area of the prawns and affects the culture of the prawns; therefore, the mesh size of the net is increased to allow the prawns to enter the net culture area 2, further expanding the culture area of the prawns.

[0052] The aeration pipes provided on the bottom frame 11 and the side frame of the net 1 are still retained when the net 1 is expanded and the mesh size of the net 1 is changed.

[0053] In the S3 step, when the ayu enters the final body growth stage, the first growth stage of the ayu is completed; when the net culture area 2 is expanded to occupy 3 / 4 of the area of the pond, which is in July-August of the next year, the ayu generally reaches a size of 0.5 kg, which has reached the processing size for early market, and is ready for the first catch;

[0054] In the S4 step, when the number of ayu for catching is about 3 / 5 of the number of ayu for stocking, the net is removed, and the remaining ayu swim in the entire pond; at this time, the density of the ayu is reduced to 1000-2000 individuals per mu, which is low-density culture, and the activity area of the fish population is spread throughout the pond; the ayu enters the second growth stage.

[0055] In the S5 step, in early September, the crude protein content of the feed is adjusted to 48%, and the fish liver oil is mixed at a ratio of 100 g per kg of feed, so that each particle of the stirred feed is fully coated with oil; the remaining low-density ayu in the pond are fed with fattening feed for 4 months, fully supplementing various nutrients and trace elements.

[0056] At the same time, the high-protein active bait feeding is strengthened, mainly from the wild Mysis resource in the crab pond, and the live Mysis is put into the chum salmon pond at the amount of 20 kg per mu. The Mysis is sufficient in source and slow in swimming, and can provide the chum salmon with high-protein live bait for all-weather feeding. The Mysis is replenished once every 30 days to maintain the bait density, so as to reduce the difficulty of chum salmon predation and improve the feeding efficiency of chum salmon.

[0057] In the S6 step, after the second growth stage of chum salmon is completed, the chum salmon size can reach 0.8-0.9 kg in early January of the third year. At this time, the market demand quantity price is high in the listing golden period of the Spring Festival, and the chum salmon in the pond can be retailed fresh and alive through fishing.

[0058] Embodiment

[0059] The chum salmon greenhouse covers an area of 12 mu, two greenhouses are built, each greenhouse covers two pond openings, the net area of a single pond is 2.3 mu, and there is no column in the pond.

[0060] The earth pool is excavated to a depth of 5 meters, the pool body is an oval pond with a length-width ratio of 2:1, the length is east-west, and the area is about 3 mu. The corners of the pond are changed from traditional square corners to arc corners to avoid dead corners of water flow. The middle of the pool bottom is excavated into a conical shape, and the water inlet of the in-situ purification equipment in the pond is placed in the conical bottom. In the later breeding process, the residual bait and feces in the pool bottom are purified by starting the purification equipment.

[0061] The in-situ purification equipment and plant floating bed are arranged in the pond, and the whole male lobster and the beneficial microorganisms are put and splashed to purify the water quality in the pond;

[0062] In the first year of releasing fry, the first and last floating frames are placed along the edge of the whole pond, each floating frame is 4 meters long and 1 meter wide, and the floating frame is filled with water hyacinth for water quality purification. Since the chum salmon breeding is in a greenhouse, it can normally overwinter and survive to purify the water quality. In the second year of releasing fry, the marketable lobsters are selected, and the 15-25 g male lobsters are selected out. At this time, the selling price is very cheap at 30 yuan / kg. The whole male lobsters with red shell and slightly hard texture are selected at a density of 30 kg per mu and put into the pond. When feeding chum salmon, the chum salmon gathers and swims in waves, and part of the feed sticks to the edge. The residual bait and feces of chum salmon in the pond are natural bait for lobsters. At the same time, the aquaculture EM bacteria are regularly splashed to purify water and improve the bottom. Through the joint action of the in-situ purification equipment, plant floating bed, whole male lobsters and beneficial microorganisms in the fish pond, the in-situ purification of the water quality in the chum salmon pond is realized, the incidence of chum salmon is reduced, and the ecological and healthy breeding of chum salmon is effectively promoted.

[0063] The all-male lobsters are released and after 2-3 months of release, during the feeding time of the huchens, the lobsters are observed and the average size of the lobsters is 40-50g, the ground cage is placed on the slope, the ice-fresh bait of the fish is placed in the cage, and the male lobsters are caught.

[0064] A new type of greenhouse is established; in the present application, a new type of greenhouse is developed, the total investment of the greenhouse is 200,000 yuan, the average investment per mu is 16,700 yuan, a new type of greenhouse without vertical columns, simple structure, short construction time, convenient fishing is formed, which is convenient for popularization and application, realizes low-cost and low-threshold entry of huchen breeding industry, and has important significance for widening the development of huchen industry; the greenhouse implements double-layer sunshade net, has good sunshade effect in summer, low indoor temperature, thin film is rolled up in summer, good ventilation, unique mountain-shaped roof design, convenient drainage in summer, multi-layer roof, good indoor heat preservation effect in winter, no snow accumulation, and the overall is very consistent with the characteristics of warm in winter and cool in summer of huchen breeding.

[0065] The new type of greenhouse is vertically stretched by three rows of steel structures to form a mountain-shaped support, the peripheral beams form a wall type column, the whole is supported by a cross steel beam as a longitudinal main beam which is 6 meters high, and the longitudinal main beam is transversely welded with three steel pipes to form three horizontal beams; the lowermost one of the three horizontal beams is 3 meters away from the ground, the middle horizontal beam is 1.5 meters away from the bottom horizontal beam, and the upper horizontal beam is vertically arranged on the top of all the steel pipes and is 1.5 meters away from the middle horizontal beam, which serves as an integrated anti-settling reinforcement. The steel pipes at the top of the peripheral beams are welded together to form a whole, and the peripheral beams include longitudinal beams and lateral beams; the height of the longitudinal beams is 1.6 meters; the lateral beams are symmetrical and descending on both sides, the middle part is the highest at 4 meters, and the lowest part on both sides is 1.6 meters and is connected with the longitudinal beams.

[0066] First, the steel cable is horizontally pulled up according to the order from the front door to the back door, the mountain-shaped steel beam is used as the support point, the middle horizontal beam is used as the support, the steel cable is horizontally pulled up to the outer peripheral beam, a steel cable support with an interval of 1 meter is formed, then the sunshade net with a light transmission efficiency of 90% is laid and fixed as the first inner sunshade in the shed;

[0067] Second, the steel cable is horizontally pulled up according to the order from left to right, the mountain-shaped steel beam is used as the support point, the upper horizontal beam and the outer peripheral beam are used as the support, the steel cable with an interval of 0.4 meters is horizontally pulled up to the steel pipe ground anchor 1.5 meters away from the outer peripheral beam on both sides of the outer peripheral beam of the greenhouse, and the first support at the bottom of the roof is formed;

[0068] Third, a large-diameter bird-proof net is laid on the surface of the bottom support steel cable, the large-diameter bird-proof net is a bird-proof net with a mesh larger than 30cm, the bird-proof net is combined and fixed with the bottom support steel cable as the second support of the roof;

[0069] Fourth, choose a period of no wind in the second support surface of the shed roof 15 silk Li De film, as the first warm shed insulation main body insulation shed surface;

[0070] Fifth, after the warm shed insulation main body shed surface is laid, immediately lay the shading net with 90% light transmission efficiency on the surface of the first warm shed insulation main body shed surface as the second warm shed insulation main body shading shed surface;

[0071] Sixth, use steel cable according to the sequence from left to right, vertically pull up the first cover of the outer vertical surface of the shed roof, and fix the steel cable to the steel pipe ground anchor on both sides of the outer ring beam 1.5 meters away from the outer periphery of the warm shed, forming the first cover of the outer vertical surface of the shed roof;

[0072] Seventh, immediately after the second warm shed insulation main body shading shed surface is laid, a large-diameter bird-proof net is laid, which is a bird-proof net with a mesh size greater than 30 cm. The bird-proof net is fixed with the horizontal steel cable of the first cover of the outer vertical surface of the shed roof as the second cover of the outer vertical surface of the shed roof, and the two layers of shed insulation shading are compressed;

[0073] Eighth, while the top membrane surface is fixed, the two layers of shed top cover are tightened, and black wavy compression membrane lines are used to compress the compression groove at the top of the ring beam, and the whole shed top of the warm shed main body is formed;

[0074] Ninth, the shed membrane of 1.6 meters is reserved for the ring beam, the bottom is provided with a membrane roller, which is convenient for rolling up for ventilation and cooling in the later period, and a 30 cm waterproof membrane is vertically laid at the bottom of the ring beam to prevent rainwater from flowing back from the outside.

[0075] American shad belongs to upper-middle layer fish and swims in the same direction all its life, allowing water to flow through gill filaments to filter oxygen, consuming a large amount of body energy to maintain survival, and having a high bait coefficient. Therefore, on the basis of conventional bottom oxygenation, an improved composite modular oxygenation mode composed of conventional bottom oxygenation, liquid oxygen and gas water oxygenation is implemented. According to the gas output of 150 cubic meters of oxygen per hour per 2.5 mu of pond, the oxygen content in the pond is kept in an oxygen-rich state.

[0076] On May 15th and June 15th, respectively, the density is set to 4000-4500 tails / pool for high-density breeding; In the traditional breeding process of shad, fry is usually concentrated for acclimation before being divided into pools. However, due to the habit of shad dying as soon as they come out of water since ancient times, the stress of shad is strong, and the damage during the process of dividing into pools is inevitable; Therefore, 1 / 10 of the area in the pond is set as a net breeding area 2 for acclimation, the mesh number of net 1 is 5, and the fry is not divided in the later period; At the same time, the new breeding method avoids the damage caused by dividing the fry in the later period.

[0077] The first growth stage of the ayu fish includes at least five body growth stages; when the ayu fish enters from the first body growth stage to the second body growth stage, the netting area is expanded by 1 / 10 of the pond area every 60 days since June; therefore, the time of one body growth stage is 60 days, and 60 days is entered into the next body growth stage; by changing the netting control of the water area, the density of the ayu fish is increased, and the ayu fish forms a migratory cluster, thereby avoiding the damage caused by the later partitioning of the pond.

[0078] When the ayu fish enters the third body growth stage, the netting culture area 2 occupies 1 / 3 of the area of the pond, and the body of the ayu fish is obviously larger than that of the lobster; when the ayu fish enters the third body growth stage, the netting culture area 2 is continuously expanded to occupy a larger area of the pond, which occupies the culture area of the shrimp and affects the culture of the shrimp; therefore, the mesh number of the netting is changed while the netting culture area 2 is expanded, and the mesh number of the netting is changed from 5 meshes to 1 mesh; so that the ayu fish in the third body growth stage cannot swim out of the netting culture area 2, and the lobster can enter the netting culture area 2, thereby further expanding the culture area of the shrimp.

[0079] After several body growth stages of the ayu fish, the first growth stage is completed; when the netting culture area 2 is expanded to 3 / 4 of the area of the whole pond, it is July-August of the next year, and the ayu fish generally reaches a specification of 0.5 kg, which has reached the pre-prepared menu processing specification for early marketing, and is ready for the first catch; when the ayu fish is caught for the first time, the netting is moved in the opposite direction, the netting culture area 2 is quickly reduced to 1 / 5 of the area of the whole pond, the fish school is surrounded into the net cage through the electric lifting net occupying 1 / 10 of the area of the whole pond, and the fish school flows into the shore collection area along the fishway at the side end of the net cage; the shore collection area is set as a square-shaped temporary canvas pond with salinity, and the salinity is 20 parts per thousand, which reduces the stress response of the ayu fish, and then the net bag filled with the ayu fish is taken out of the water and placed into the prepared ice storage box, and the ayu fish is stacked in the way of one layer of ice and one layer of ayu fish, and then sent to the processing plant for processing; the ayu fish culture density in the pond is reduced, the part of the culture cost is recovered, and the next step will effectively promote the low-density rapid growth of the stored fish.

[0080] The traditional ayu fish culture needs 18-20 months to reach a large specification, and only one season of live fish is produced in a year, and the sales window period is extremely short. In the traditional culture, from May of the second year when the fry is released, the water temperature rises, the feed feeding increases under the condition of high-density culture, and the self-purification capacity of the water body gradually decreases; due to the limitation of the water bearing capacity, the culture risk rises sharply, and the pond explosion often occurs in the summer high-temperature season.

[0081] The new culture mode increases the density and shortens the culture period. By changing the size of the pond, small-sized 0.4-0.5 kg ayu fish meeting the requirements of pre-prepared dishes are caught, quickly transferred to a processing plant to remove blood and internal organs, and then frozen by using liquid nitrogen quick-freezing technology to make pre-prepared dishes, so that one ayu fish can serve one meal. The selling price is also reduced from the high-end ayu fish with a size of 0.8-1 kg and a price of 240-300 yuan per tail to the people-friendly price of 0.4-0.5 kg and 60-80 yuan per tail. The liquid nitrogen quick-freezing technology and modern logistics technology make the limited sales window period of ayu fish become a year-round express sales, and make the ayu fish that comes with the Qingming Festival become a delicacy that can be eaten at any time. The liquid nitrogen quick-freezing technology and modern logistics technology actively promote the innovation of the culture mode and the sales mode, and promote the innovative development of the ayu fish industry chain.

[0082] When the number of caught ayu fish is about 3 / 5 of the number of released ayu fish, the net is removed, and the remaining ayu fish swim in the whole pool. At this time, the density of ayu fish is reduced to 1000-2000 tails per mu, and low-density culture is carried out. At the same time, the feeding of high-protein active bait is strengthened, mainly from the wild copepod resources in the crab pond. The live copepods are put into the ayu fish pool at a rate of 20 kg per mu. In early January of the third year, the size of ayu fish can reach 0.8-0.9 kg, and the second growth stage of ayu fish is completed. At this time, it is the golden period of market demand for high-priced ayu fish in the Spring Festival market. The ayu fish in the pool are sold fresh and alive by fishing.

[0083] At the same time, in early January of the third year, net bags with a mesh density of 40 meshes are placed in the water lifting oxygenator. The entrance of the net bag is 1 meter below the water surface, and the rest is connected to the water surface by a floating ball. The depth of the net bag is 2 meters, and the length is 10 meters. It is specially used to collect copepod larvae and adult shrimps, which are collected every hour and used to feed the parent ayu fish in the ayu fish breeding workshop to promote the development of the parent gonad.

[0084] The above is a preferred embodiment of the present application. It should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present application. These improvements and refinements should also be considered as within the scope of the present application.

Claims

1. A method for the ecological breeding of high-density of American shad, characterized in that: It comprises the following steps: S1: Establishing a net cage culture area (2) as a fry centralized domestication area in a pond using a purse seine (1) with an oxygenation device on the purse seine (1) and pond oxygenation by aeration in subsequent steps; S2: In the first growth stage of the ayu, as the fry grows, the centralized domestication area is gradually expanded by gradually changing the purse seine (1); S3: When the first growth stage of the ayu is completed, the first catch of the ayu is carried out; S4: When the first catch of the ayu reaches a low-density culture level, the ayu is stopped and the purse seine (1) is removed, and the ayu enters the second growth stage; S5: In the second growth stage of the ayu, the remaining ayu is fattened by changing the bait; S6: When the second growth stage of the ayu is completed, the remaining ayu is caught; The first growth stage of the ayu in the S2 step comprises at least five body growth stages; the body growth stage expands the net cage culture area (2) once when the ayu enters the second body growth stage from the first body growth stage; the net cage culture area (2) expands once each time the ayu enters the next body growth stage; The first body growth stage and the second body growth stage use an initial purse seine (1) with a mesh size that prevents the ayu from swimming out of the net cage culture area (2), and the pond outside the net cage culture area (2) is used to culture shrimps that cannot enter the net cage culture area (2); When the ayu enters the third body growth stage, the ayu is significantly larger than the shrimps; the mesh size of the purse seine is changed while the net cage culture area (2) is expanded, so that the ayu in the third body growth stage cannot swim out of the net cage culture area (2), and the shrimps can enter the net cage culture area (2); the mesh size of the purse seine used in the subsequent body growth stages is the mesh size of the purse seine used in the third body growth stage; when the ayu enters the last body growth stage, the first growth stage of the ayu is completed; When the ayu enters the third body growth stage, the net cage culture area (2) is expanded to occupy part of the pond, reducing the area for shrimp culture; The net cage culture area (2) is expanded by increasing the number of purse seines (1); each time the net cage culture area (2) is expanded, the net cage culture area (2) for the next body growth stage is set up, and then the original purse seines (1) of the net cage culture area (2) are removed.

2. The method of claim 1, wherein the method is suitable for ecological breeding of high-density American shad. The purse seine (1) comprises a bottom frame (11), an upper frame (12), and a side frame; the bottom frame (11) of the purse seine (1) is provided with an aeration pipe along the length direction, and the aeration pipe is provided with air outlets arranged along the length direction; the air outlets of the aeration pipe continuously emit bubbles upward.

3. The method of claim 2, wherein the method is suitable for ecological breeding of high-density American shad. The bottom frame (11) of the purse seine (1) continuously emits bubbles, forming a bubble wall on one side of the area from the bottom frame (11) to the upper frame (12) of the purse seine (1), which prevents the ayu from touching the purse seine (1).

4. The method of claim 3, wherein the method is characterized by: The bubbles continuously rising from the bottom (11) form a fast upward water flow far from the side of the net, and the salmon swim upward under the effect of the water flow. The sound produced by the breaking of the bubbles when they rise to the water surface drives the salmon away. At the same time, the water at the upper part of the net breeding area (2) flows towards the center of the net breeding area (2) due to the fast upward water flow below. The water flow at the upper part of the net breeding area (2) drives the salmon away from the net (1).

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