Mudflat shellfish breeding method

Abstract

The invention relates to the field of aquaculture, and discloses a mud flat shellfish breeding method which comprises the following steps: mixing algae powder and fresh microalgae in a feeding device to obtain bait; the baits are fed to mud flat shellfish larvae through a feeding device, and seedling raising is conducted; wherein in the bait, the cell number ratio of the algae powder to the fresh microalgae is 100 or less; wherein the mixing conditions are as follows: the pressure is negative pressure, and the time is more than 5 minutes. According to the method, the hidden danger that culture is unstable when the algae powder is used for replacing fresh algae can be reduced, and mixed feeding of the microalgae and the algae powder for full-artificial breeding of the mud flat shellfish is achieved.

Description

Technical Field

[0001] The invention relates to the field of aquaculture, and in particular to a method for raising shellfish seedlings on a tidal flat. Background Art

[0002] The traditional fully artificial breeding and seedling raising process for tidal flat shellfish generally uses fresh microalgae as feed. The traditional model of single-cell algae cultivation is greatly affected by factors such as light, temperature, and salinity, making the cultivation of single-cell microalgae bait more difficult. These unfavorable external conditions and pollution from other organisms cannot stably guarantee sufficient fresh bait supply, resulting in the failure of large-scale seedling production or poor returns due to the interruption of the food chain before the cultivated economic animal larvae grow to commercial specifications.

[0003] At present, photobioreactors are generally used to supplement the cultivation of single-cell microalgae. This device is an improved model of traditional algae cultivation available in China. The equipment can be used for artificial lighting and closed-loop cultivation to obtain algae liquid with a higher concentration. Its advantage is that it is not overly affected by the external environment, but it also has defects, including unstable effects, poor artificial lighting effects, small culture water bodies, low microalgae yields and high costs.

[0004] According to the existing experience in raising seedlings of microalgae products (algae powder), since the seedlings have very high requirements for water quality, microalgae products will affect and pollute the water quality when fed. In particular, once the inactive feed sinks to the bottom, it is easy to mix with the mud and sand and is difficult to separate, and is more likely to deteriorate. Therefore, there is an urgent need to provide a method that can ensure the stable large-scale artificial raising of tidal flat shellfish. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem in the prior art that large-scale breeding of tidal flat shellfish is difficult to operate stably, and to provide a method for breeding tidal flat shellfish, which can achieve large-scale breeding of tidal flat shellfish without completely using living microalgae.

[0006] In order to achieve the above object, the present invention provides a method for raising shellfish seedlings on a tidal flat, the method comprising:

[0007] (1) mixing algae powder and fresh microalgae in a feeding device to obtain bait;

[0008] (2) feeding the bait to the larvae of the tidal flat shellfish through a feeding device and performing a seedling treatment;

[0009] Wherein, in the bait, the cell number ratio of algae powder to fresh microalgae is less than 100;

[0010] The mixing conditions include: negative pressure and a mixing time of more than 5 minutes.

[0011] Preferably, in the bait, the cell number ratio of algae powder to fresh microalgae is 1 or less.

[0012] Preferably, the feeding device comprises a mixing device capable of floating on a water floating device and arranged on the water floating device.

[0013] Preferably, the mixing device is provided with a stirring roller for mixing and a sealing cover, and the sealing cover is used to close and seal the mixing device so that its inner cavity is sealed and isolated from the outside.

[0014] Preferably, the feeding device is also equipped with a vacuum pump for providing a negative pressure environment inside the mixing device.

[0015] Preferably, the mixing device is also connected to an oxygenation pump, and the oxygenation pump is used to oxygenate the bait in the mixing device.

[0016] Through the above technical scheme, using part of the microalgae products (algae powder) to replace fresh bait can well replace the traditional live bait seedling method, alleviate the cultivation pressure of fresh microalgae, solve the problem of seedling food supply, and under optimal conditions, it can also improve the use effect of algae powder, achieve the same or even slightly better use effect as fresh microalgae as bait, reduce the hidden dangers of using algae powder to replace fresh algae, maintain a high survival rate of shellfish, and realize the mixed feeding of microalgae and algae powder for full-worker seedling cultivation of tidal flat shellfish. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the upper half of the feeding device of the present invention;

[0018] Figure 2 It is a longitudinal section schematic diagram of the upper half of the feeding device of the present invention;

[0019] Figure 3 is a schematic cross-sectional view of a bottom-sinking stand in the feeding device of the present invention;

[0020] Figure 4 It is a schematic longitudinal section of a bottom-sinking stand in the feeding device of the present invention;

[0021] Figure 5 The effect of feeding algae powder and fresh microalgae in different proportions on the shell length of mud cockle larvae is shown;

[0022] Figure 6 The results show the effect of feeding algae powder and fresh microalgae in different proportions on the density of mud cockle larvae in the planktonic stage.

[0023] Figure 7 The effect of feeding algae powder and fresh microalgae in different proportions on the shell length of clam larvae is shown;

[0024] Figure 8 The effect of feeding algae powder and fresh microalgae in different proportions on the metamorphosis rate of clam larvae is shown;

[0025] Fig. 9 The results show the effect of feeding algae powder and fresh microalgae in different proportions on the shell length of Sinonovacula constricta larvae.

[0026] Description of Reference Numerals

[0027] 1. Water floating device; 11. Floating body; 12. Propeller; 13. Steering blade; 14. Transmission shaft; 15. Transmission rod; 2. Mixing device; 21. Stirring roller; 22. Sealing cover; 3. Oxygenation pump; 4. Inner cavity; 5. Vacuum pump; 6. Transport connecting pipe; 7. Bottom stand; 71. Bracket; 72. First water inlet; 73. Water outlet; 74. Second water inlet. DETAILED DESCRIPTION

[0028] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] The present invention provides a method for raising shellfish seedlings on a tidal flat, the method comprising:

[0030] (1) mixing algae powder and fresh microalgae in a feeding device to obtain bait;

[0031] (2) feeding the bait to the larvae of the tidal flat shellfish through a feeding device and performing a seedling treatment;

[0032] Wherein, in the bait, the cell number ratio of algae powder to fresh microalgae is less than 100 (for example, it can be 0.01, 0.05, 0.1, 0.5, 1, 5, 10, 20, 100 or less and any range between any two values, preferably less than 1);

[0033] The mixing conditions include: negative pressure and a mixing time of more than 5 minutes.

[0034] In the present invention, the tidal flat shellfish may be cockles, clams or razor clams, such as mud clams, razor clams or clams, and the larvae thereof may be planktonic larvae or juvenile shellfish. Preferably, when the larvae are planktonic larvae, the larvae are cultured at a density of 10-15 grains / mL.

[0035] Preferably, when the larvae are juvenile spat, the larvae are cultured at a density of 100,000 to 1,000,000 larvae / m 2.

[0036] The fresh microalgae and algae powder described in the present invention can be microalgae that can be used for beach shellfish seedlings, such as Chlorella, Triangular Phaeodactylum, Chrysophyll, Ceratocystis and Platyhelminthes, and those skilled in the art can select suitable microalgae as needed. There is no particular limitation on the cultivation method or acquisition method of the microalgae, and it can be produced or obtained according to conventional methods in the art.

[0037] In one embodiment of the present invention, in the bait, the algae powder and the fresh microalgae are each independently golden algae and / or diatoms, preferably at least one of Isochrysis sp., Dicrateria sp., Cyclotella sp., Phaeodactylum tricornutum and Chaetoceros sp., such as Isochrysis zhangjiangensis, Dicrateria zhanjiangensis and the like.

[0038] In the present invention, both the fresh microalgae and algae powder can be obtained from Guotou Microalgae. The number of algae cells in the bait is not particularly limited. Preferably, the number of algae cells in the bait is 1*10 8 cells / mL or more.

[0039] Preferably, in the early stage of the shell top larvae, the amount of bait fed each time makes the bait density in the water body 1*10 4 -4*10 4 cell / mL.

[0040] Preferably, in the late stage of the shell-top larvae, the amount of bait fed each time makes the bait density in the water body 5*10 4 -8*10 4 cell / mL.

[0041] Preferably, during the juvenile period, the amount of bait fed each time is such that the density of bait in the water body is 1*10 5 -1.5*10 5 cell / mL.

[0042] The number of times of feeding per day can be selected according to the specific situation, for example, 2-3 times a day can be fed.

[0043] Preferably, the conditions for raising seedlings include: temperature of 25-30°C, salinity of 24-27, pH of 7.8-8.4, and dissolved oxygen of 8 mg / L or more.

[0044] Preferably, the water for raising seedlings is secondary sand-filtered seawater. The water for raising seedlings can be treated with 3-5 mg / L of disodium EDTA, and the ammonia nitrogen content therein is controlled to be ≤0.1 mg / L. For other conditions, see the conditions for raising seedlings.

[0045] Preferably, the feeding device comprises a floating device 1 capable of floating on the water and a mixing device 2 arranged on the floating device 1, such as Figure 1 and 2 It should be understood that the mixing device 2 can be placed inside the water floating device or on the top of the water floating device, without any special limitation, as long as the mixing device can be fixed.

[0046] Preferably, the water floating device 1 includes a float 11 floating on the water surface and a driving device for driving the feeding device to cruise along a set route. Preferably, the driving device is located at the tail end of the water floating device 1, and includes a propeller 12 that can be driven to rotate based on a servo motor and a steering device, wherein the steering device includes a direction blade 13, a transmission shaft 14 connected to the direction blade 13, and a transmission rod 15 connected to the main shaft of the motor for steering to drive the transmission shaft 14 to swing. The transmission shaft can be an L-shaped transmission shaft, such as Figure 1 and 2 shown.

[0047] Preferably, the mixing device 2 is provided with a stirring roller 21 for mixing and a sealing cover 22, wherein the sealing cover 22 is used to close and seal the mixing device 2 so that the inner cavity 4 is sealed and isolated from the outside, for example, Figure 1 and 2 In the present invention, the mixing process is accompanied by stirring, and the stirring speed is not particularly limited, and can be a conventional stirring speed, such as 100 rpm or more, such as 200 rpm, 500 rpm, 800 rpm, 1000 rpm, 2000 rpm, 5000 rpm or more, and any range between any two values.

[0048] Preferably, the feeding device 2 is further provided with a vacuum pump 5 for providing a negative pressure environment inside the mixing device 2. The inner cavity 4 of the mixing device 2 is a sealed cavity after the sealing cover 22 is closed. The vacuum pump 5 is used to evacuate the inner cavity 4 to form a negative pressure, which is used to discharge the air in the algae powder through air pressure changes, for example, Figure 1 and 2 shown.

[0049] Preferably, the mixing device 2 is also connected to an oxygenation pump 3 , and the oxygenation pump 3 is used to oxygenate the bait in the mixing device 2 .

[0050] Preferably, the method further comprises: oxygenating the mixed bait.

[0051] Preferably, the oxygenation conditions are such that the oxygen content in the bait is above 8 mg / L.

[0052] Preferably, in the feeding device, the bottom of the water floating device 1 is also connected to a bottom sinking frame 7, the bottom sinking frame 7 includes a hollow cavity equipped with a water pressure pump, and a bracket 71 is provided at the bottom, for example, Figure 3 and 4 The shape of the bracket 71 is not particularly limited, and can be, for example, circular.

[0053] Preferably, the upper surface of the hollow cavity is provided with a first water inlet 72 and a water outlet 73 at the front and rear, respectively, and the two are connected through a pipeline via a water pressure pump; wherein the first water inlet 72 draws water from above the bottom stand 7, and after passing through the inner cavity of the bottom stand 7, opens obliquely upward from the water outlet 73 toward the water surface, and the inner diameter of the bottom stand 7 in the middle of the first water inlet 72 and the water outlet 73 is set in a narrowed shape, for example, as shown in Figure 3 and 4 shown.

[0054] Preferably, the bottom sinking frame 7 is further provided with a second water inlet 74, the water inlet end of the second water inlet 74 is arranged close to the bracket 71 at the bottom of the bottom sinking frame 7, and the other end is connected to the front end of the water pressure pump, for example, Figure 3 and 4 shown.

[0055] Preferably, in the feeding device, the mixing device 2 is connected to the front end of the water pump of the bottom stand 7 through the conveying connecting pipe 6, for example, Figure 2-4 shown.

[0056] In a preferred embodiment of the present invention, the feeding device comprises: the feeding device comprises a mixing device 2 that can float on a water floating device 1, arranged on the water floating device 1, and a bottom sinking stand 7 connected to the water floating device 1. The water floating device 1 comprises a floating body 11 floating on the water surface and a driving device that drives the feeding device to cruise along a set route. The driving device is located at the tail end of the water floating device 1, and comprises a propeller 12 that can be driven to rotate based on a servo motor and a steering device. The steering device comprises a direction blade 13, an L-shaped transmission shaft 14 connected to the direction blade 13, and a transmission rod 15 connected to the main shaft of the motor for steering to drive the transmission shaft 14 to swing. The mixing device 2 is provided with a stirring roller 21 and a sealing cover 22 for mixing. The sealing cover 22 is used to close and seal the mixing device 2 so that its inner cavity 4 is sealed and isolated from the outside. The feeding device 2 is also equipped with a vacuum pump 5 for providing a negative pressure environment inside the mixing device 2; and is connected to an oxygenation pump 3, and the oxygenation pump 3 is used to oxygenate the bait in the mixing device 2. The bottom sinking frame 7 includes a hollow cavity equipped with a water pressure pump, and a bracket 71 is provided at the bottom. The upper surface of the hollow cavity is provided with a first water inlet 72 and a water outlet 73 at the front and back, respectively, which are connected through a pipeline via a water pressure pump; wherein the first water inlet 72 absorbs water from the top of the bottom sinking frame 7, and opens obliquely upward from the water outlet 73 toward the water surface after passing through the inner cavity of the bottom sinking frame 7, and the inner diameter of the bottom sinking frame 7 in the middle of the first water inlet 72 and the water outlet 73 is configured in a tapered shape. The bottom sinking frame 7 is also provided with a second water inlet 74, the water inlet end of the second water inlet 74 is arranged close to the bracket 71 at the bottom of the bottom sinking frame 7, and the other end is connected to the front end of the water pressure pump, wherein the mixing device 2 is connected to the front end of the water pressure pump of the bottom sinking frame 7 via a conveying connecting pipe 6. For details, please refer to Figure 1-4 The feeding device shown.

[0057] The feeding device of the present invention can alleviate the problem that algae powder sinks to the bottom after use, which makes it difficult to be ingested by filter-feeding shellfish and causes it to sink to the bottom and deteriorate, and can also alleviate the problem that algae powder sinks to the bottom and stratifies.

[0058] The present invention will be described in detail below through examples.

[0059] In the following examples, unless otherwise specified, the reagents and materials used were commercially available, and the methods adopted were conventional methods in the art.

[0060] The microalgae used in the seedling cultivation process is Isochrysis Zhanjiangensis, which is obtained through four-stage culture. Among them, 1g of Isochrysis algae powder (freeze-dried) contains about 30 billion cells.

[0061] The aquaculture water is secondary sand-filtered seawater with a salinity of 24-26, a pH of 7.8-8.4, dissolved oxygen ≥5 mg / L, ammonia nitrogen ≤0.1 mg / L, and 4 mg / L of disodium EDTA is added.

[0062] The following examples were conducted in a farm located in the coastal area of ​​Wenzhou, Zhejiang Province. The area of ​​the cement pond where the larvae were raised was 30 m 2 .

[0063] In the following examples, we will use Figure 1-4 The feeding device shown is used for preparing and feeding bait, wherein the feeding device comprises: the feeding device comprises a mixing device 2 which can float on a water floating device 1, arranged on the water floating device 1, and a bottom sinking stand 7 connected to the water floating device 1. The water floating device 1 comprises a floating body 11 floating on the water surface and a driving device for driving the feeding device to cruise along a set route, the driving device is located at the tail end of the water floating device 1, and comprises a propeller 12 which can be driven to rotate based on a servo motor, and a steering device, the steering device comprises a direction blade 13, an L-shaped transmission shaft 14 connected to the direction blade 13, and a transmission rod 15 connected to the main shaft of the motor for steering and driving the transmission shaft 14 to swing. The mixing device 2 is provided with a stirring roller 21 for mixing and a sealing cover 22, the sealing cover 22 is used to close and seal the mixing device 2, so that its inner cavity 4 is sealed and isolated from the outside. The feeding device 2 is also equipped with a vacuum pump 5 for providing a negative pressure environment inside the mixing device 2; and is connected to an oxygenation pump 3, and the oxygenation pump 3 is used to oxygenate the bait in the mixing device 2. The bottom sinking frame 7 includes a hollow cavity equipped with a water pressure pump, and a bracket 71 is provided at the bottom. Among them, the upper surface of the hollow cavity is provided with a first water inlet 72 and a water outlet 73 at the front and back, respectively, and the two are connected through a pipeline via a water pressure pump; wherein the first water inlet 72 absorbs water from the top of the bottom sinking frame 7, and after passing through the inner cavity of the bottom sinking frame 7, it opens obliquely upward from the water outlet 73 toward the water surface, and the inner diameter of the bottom sinking frame 7 in the middle of the first water inlet 72 and the water outlet 73 is configured in a constricted shape. The bottom sinking frame 7 is also provided with a second water inlet 74, the water inlet end of the second water inlet 74 is arranged close to the bracket 71 at the bottom of the bottom sinking frame 7, and the other end is connected to the front end of the water pressure pump, wherein the mixing device 2 is connected to the front end of the water pressure pump of the bottom sinking frame 7 through the conveying connecting pipe 6.

[0064] Excel and SPSS one-way analysis of variance (ANOVA) were used to analyze the effects of different algae powders and fresh microalgae feeding on the growth and survival of tidal flat shellfish larvae, and the differences were significant at P<0.05.

[0065] Preparation Example 1

[0066] This preparation example is used to illustrate the preparation of bait.

[0067] In the feeding device, the microalgae powder and the aquaculture water are stirred and mixed evenly, stirred for 5 minutes under negative pressure conditions, and the stirring speed is above 3000rpm. Then, the mixed material is mixed with the microalgae liquid in a certain proportion and oxygenated, and the oxygen content in the obtained bait is above 8mg / L.

[0068] Among them, the amount of algae powder used is converted into the number of cells used in fresh bait (referring to the same cell mass ratio), and the amount of algae powder used is obtained by conversion (1 gram of algae powder is about 30 billion algae cells).

[0069] Example 1

[0070] This embodiment is used to illustrate the breeding of planktonic larvae of tidal flat shellfish.

[0071] Take mudflat shellfish (mud clams, clams and razor clams) with mature gonads, dry them in the shade, and artificially induce spawning to obtain fertilized eggs of mudflat shellfish. After they develop into straight-line hinged larvae (also known as D-shaped larvae), they are selected and collected using a 300-mesh silk screen.

[0072] The feeding density of the bait in the first 1-4 days of the shell top larvae is 1-4×10 4 cell / ml, the shell-top larvae were fed 5×10 4 -8×10 4 The experiment was conducted with cell / ml as the standard.

[0073] Four algae powder and fresh microalgae ratio gradients (0%, 40%, 80%, 100%) were set, and three parallels were set in each group. The experiment was carried out in a plastic bucket (water body 60L), the experimental water temperature was 25-30℃, and continuous and uniform aeration was used for oxygenation. During the experiment, bait was fed twice a day, at 9:00 and 15:00 respectively.

[0074] Before feeding, observe the larvae's gastrointestinal tract, vitality, survival rate and other indicators, and observe again 1-2 hours after feeding; record the larval growth and survival data. 1 hour and 24 hours after feeding, measure the changes in water chemical oxygen demand (COD), suspended particles, phosphate, nitrate, nitrite and ammonium salts.

[0075] (1) Effects of different proportions of algae powder and fresh microalgae mixed feeding on the growth and survival of mud clam larvae and water quality monitoring analysis

[0076] The initial shell length of the mud clam planktonic larvae is 60 μm, and the density is 10-12 particles / ml. The shell length and density changes of the mud clam larvae during the culture process are as follows: Figure 5 and Figure 6 shown.

[0077] The results showed that under the continuous feeding of 0% algae powder + 100% fresh microalgae, 40% algae powder + 60% fresh microalgae, 80% algae powder + 20% fresh microalgae, and 100% algae powder + 0% fresh microalgae, the larvae of mud clam in the experimental group could grow. At 9d-18d, the shell length and seedling density of the low algae powder group (0% algae powder + 100% fresh microalgae, 40% algae powder + 60% fresh microalgae) were significantly higher than those of the high algae powder group (80% algae powder + 20% fresh microalgae, 100% algae powder + 0% fresh microalgae).

[0078] Tables 1 and 2 show the effects of feeding a combination of microalgae products and fresh bait on the changes in water quality for cultivating mud clam larvae at 3 days and 15 days after seedling cultivation, respectively.

[0079] Table 1

[0080]

[0081] Table 2

[0082]

[0083]

[0084] As shown in Table 1, on the 3rd day of cultivation of mud clam larvae, except for 24 hours after feeding, the ammonium concentration of the 0% algae powder group was significantly lower than that of the other three experimental groups, and there were no significant differences in other water quality indicators among the four experimental groups at 1 hour and 24 hours.

[0085] After feeding for 24 hours on the 15th day of the cultivation of mud clam larvae, the concentrations of phosphate, nitrite and nitrate in the 0% algae powder group were significantly higher than those in the other three experimental groups, indicating that the use of algae powder makes the water quality discharged after the seedling cultivation better than that of fresh algae, and the use of algae powder for seedling cultivation is more environmentally friendly. This may be caused by the residual nutrients in the culture medium contained in the fresh algae liquid. The nitrite content of the 0% algae powder group was higher than that of the other three experimental groups when the mud clam larvae were fed for 1 hour on the 15th day of the cultivation.

[0086] (2) Effects of feeding algae powder and fresh microalgae in different proportions on the growth and survival of clam larvae and water quality monitoring and analysis

[0087] The initial shell length of the planktonic larvae of the clam is 140 μm, the density is 10-12 grains / ml, and the effects of algae powder and fresh microalgae mixed feeding in different proportions on the shell length change and metamorphosis rate of the clam larvae are shown in the following table. Figure 7 and Figure 8 shown.

[0088] The results showed that there was no significant difference in shell length among the four experimental groups when algae powder and fresh microalgae were mixed. On the sixth day, the metamorphosis rate of the 100% algae powder group was lower than that of the other three experimental groups, and there was no significant difference among the other three experimental groups (P<0.05).

[0089] Table 3 shows the effects of feeding a combination of microalgae products and fresh bait on the changes in water quality for clam larvae cultivation on day 2 of seedling cultivation.

[0090] Table 3

[0091]

[0092] As can be seen from Table 3, when the clam larvae were fed with bait on the 2nd day of cultivation, the concentrations of phosphate, nitrite and ammonium salt in the 0% algae powder group were significantly higher than those in the other three experimental groups, indicating that the use of algae powder makes the water quality discharged after seedling cultivation better than that using fresh algae for seedling cultivation, and the use of algae powder for seedling cultivation is more environmentally friendly. This may be because the fresh algae liquid contains residual nutrients in the culture medium. This can be explained by the fact that the phosphate and nitrite content of the 0% algae powder group was higher than that of the other three experimental groups when the clam larvae were fed for 1 hour on the 2nd day of cultivation.

[0093] (3) Effects of different proportions of algae powder and fresh microalgae mixed feeding on the growth of Sinonovacula constricta larvae

[0094] The initial shell length of Sinonovacula constricta larvae is 93 μm, and the density is 10-15 particles / ml. The shell length changes of Sinonovacula constricta larvae during the culture process are shown in the following table. Fig. 9 shown.

[0095] Under the continuous feeding of 0% algae powder + 100% fresh microalgae, 40% algae powder + 60% fresh microalgae, 80% algae powder + 20% fresh microalgae, and 100% algae powder + 0% fresh microalgae, the larvae of the experimental groups were able to grow. At 3 days, the shell length of the low algae powder group (0% algae powder + 100% fresh microalgae, 40% algae powder + 60% fresh microalgae) was significantly higher than that of the high algae powder group (80% algae powder + 20% fresh microalgae, 100% algae powder + 0% fresh microalgae), and there was no significant difference between the 0% algae powder group and the 40% algae powder group.

[0096] Example 2

[0097] This embodiment is used to illustrate the breeding of juvenile shellfish on tidal flats.

[0098] Select the young clams, clams and razor clams with good and stable vitality after metamorphosis and attachment. Specification: 8 to 20 million pieces / jin, density controlled at 36.7g / m 2 .

[0099] Four gradients of different cell number ratios of algae powder and fresh microalgae were set (the content of algae powder in terms of cell number was 0%, 40%, 80%, and 100%, respectively), and three parallel experiments were set up in each experimental group. The experiment was carried out at 30m 2The experiment was conducted in a cement pool, with a water temperature of 28-29°C and a salinity of 24-26, and continuous and uniform aeration. Feeding method: During the experiment, the bait was fed 6 times a day, at 6:00, 8:00, 10:00, 12:00, 14:00, and 16:00. After feeding, the algae cell density in the water was controlled at 1*10 5- 1.5*10 5 Observation of spat: Observe the gastrointestinal tract, vitality, survival rate and other indicators of spat before feeding, and observe again 1-2 hours after feeding; record the data of spat feeding, growth, survival and other data.

[0100] (1) Effects of different proportions of microalgae products and fresh bait on the growth of juvenile Sinonovacula constricta

[0101] The initial specification of Sinonovacula constricta spat is 20 million pieces / jin, and the initial mass is 1 kg (i.e. 40 million pieces). The weight change results of Sinonovacula constricta spat during the culture process are shown in Table 4.

[0102] Table 4

[0103] time 0% Algae powder 40% Algae Powder 80% Algae Powder 100% Algae Powder Day 1 1kg 1kg 1kg 1kg Day 5 2kg 2.2kg 1.9kg 2kg Day 10 3.5kg 3.6kg 2.8kg 2.5kg

[0104] The specifications measured on the 10th day were: 4.2 million grains / catties in the 0% algae powder group, 4.5 million grains / catties in the 40% algae powder group, 2.85 million grains / catties in the 80% algae powder group, and 2.8 million grains / catties in the 100% algae powder group. It can be concluded that in the cultivation process of novax clams, microalgae products can be successfully used to replace 40-100% of fresh bait. Among them, replacing 40% of fresh bait and mixing it with fresh bait has the best breeding effect, which is better than 100% fresh bait breeding. The weight and survival rate of novax clams obtained are the highest, with the highest survival rate of 80%. The survival rates of the 0% algae powder group, 80% algae powder group and 100% algae powder group are 75%, 40% and 35% respectively.

[0105] (2) Effects of feeding different proportions of microalgae products and fresh bait on the growth of juvenile clams

[0106] The initial size of clam spat was 50 million pieces / jin, and the initial mass was 1 kg. The weight change results of clam spat during the culture process are shown in Table 5.

[0107] Table 5

[0108] time 0% Algae powder 40% Algae Powder 80% Algae Powder 100% Algae Powder Day 1 1kg 1kg 1kg 1kg Day 5 1.5kg 1.6kg 1.3kg 1.2kg Day 10 2.2kg 2.4kg 1.8kg 1.5kg

[0109] The specifications measured on the 10th day were: 12.1 million grains / catties in the 0% algae powder group, 12.5 million grains / catties in the 40% algae powder group, 8.53 million grains / catties in the 80% algae powder group, and 8 million grains / catties in the 100% algae powder group. It can be concluded from Table 5 that in the cultivation process of clam juveniles, the microalgae products can be mixed with 40% algae powder + 60% fresh bait for the best effect. The 40% algae powder group had the best seedling effect, and the number and survival rate of clam juveniles obtained were the highest, with the highest survival rate of 61.2%. The survival rates of the 0% algae powder group, 80% algae powder group and 100% algae powder group were 53%, 30% and 24% respectively.

[0110] (3) Effects of feeding different proportions of microalgae products and fresh bait on the growth of juvenile mud clams

[0111] The initial specification of mud clam juveniles was 8.36 million pieces / jin, and the initial mass was 1100g. The weight change results of mud clam juveniles during the culture process are shown in Table 6.

[0112] Table 6

[0113] time 0% Algae powder 40% Algae Powder 80% Algae Powder 100% Algae Powder Day 0 1100g 1100g 1100g 1100g Day 5 2100g 2200g 1900g 1800g Day 10 3800g 3850g 2800g 2550g

[0114] The specifications tested on the 10th day were: fresh bait group (0% algae powder group) 1.86 million grains / catties, 40% algae powder group 2.12 million grains / catties, 80% algae powder group 2 million grains / catties, 100% algae powder group 1.92 million grains / catties. During the cultivation of mud clam juveniles, the best effect was achieved when the microalgae products were mixed with fresh bait at a ratio of 40%, and the highest number of mud clam juveniles was obtained.

[0115] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for raising shellfish seedlings on tidal flats, characterized in that: The method includes: (1) mixing algae powder and fresh microalgae in a feeding device to obtain bait; (2) feeding the bait to the larvae of the tidal flat shellfish through a feeding device and performing a seedling treatment; Wherein, in the bait, the cell number ratio of algae powder to fresh microalgae is less than 100; The mixing conditions include: negative pressure and a mixing time of more than 5 minutes.

2. The method according to claim 1, wherein: In the bait, the algae powder and the fresh microalgae are each independently golden algae and / or diatoms, preferably at least one selected from Isochrysis chrysophylla, Chrysophyllum formosum, Chaetoceros hornwort, Thalassiosira marinum, Cyclotella, and Phaeodactylum tricornutum; and / or Wherein, in the bait, the cell number ratio of algae powder to fresh microalgae is less than 1.

3. The method according to claim 1 or 2, wherein: The feeding device comprises a floating device (1) capable of floating on the water and a mixing device (2) arranged on the floating device (1); Preferably, the water floating device (1) comprises a buoy (11) floating on the water surface and a driving device for driving the feeding device to cruise along a set route.

4. The method according to claim 3, wherein: The driving device is located at the tail end of the water floating device (1), and comprises a propeller (12) that can be driven to rotate by a servo motor and a steering device, wherein the steering device comprises a direction blade (13), a transmission shaft (14) connected to the direction blade (13), and a transmission rod (15) connected to the main shaft of a motor for steering and driving the transmission shaft (14) to swing.

5. The method according to claim 3, wherein: The mixing device (2) is provided with a stirring roller (21) for mixing materials and a sealing cover (22), wherein the sealing cover (22) is used to close and seal the mixing device (2) so that its inner cavity (4) is sealed and isolated from the outside; Preferably, the feeding device is further provided with a vacuum pump (5) for providing a negative pressure environment inside the mixing device (2); Preferably, the mixing device (2) is also connected to an oxygenation pump (3), and the oxygenation pump (3) is used to oxygenate the bait in the mixing device (2); Preferably, the method further comprises: oxygenating the mixed bait; Preferably, the oxygenation conditions are such that the oxygen content in the bait is above 8 mg / L.

6. The method according to claim 4, wherein: In the feeding device, the bottom of the water floating device (1) is also connected to a bottom sinking frame (7), the bottom sinking frame (7) includes a hollow cavity equipped with a water pressure pump, and a bracket (71) is provided at the bottom. The upper surface of the hollow cavity is provided with a first water inlet (72) and a water outlet (73) at the front and rear, respectively, and the two are connected through a pipeline via a water pressure pump; the first water inlet (72) draws water from above the bottom frame (7), and after passing through the inner cavity of the bottom frame (7), it opens obliquely upward from the water outlet (73) toward the water surface, and the inner diameter of the bottom frame (7) in the middle of the first water inlet (72) and the water outlet (73) is configured in a constricted shape; The sinking frame (7) is also provided with a second water inlet (74), the water inlet end of the second water inlet (74) is arranged close to the bracket (71) at the bottom of the sinking frame (7), and the other end is connected to the front end of the water pressure pump.

7. The method according to claim 6, wherein: In the feeding device, the mixing device (2) is connected to the front end of the water pressure pump of the bottom support (7) via a conveying connection pipe (6).

8. The method according to any one of claims 1 to 7, wherein: The tidal flat shellfish are cockles, clams or razor clams; Preferably, when the larvae are planktonic larvae, the larvae are cultured at a density of 10-15 particles / mL; Preferably, when the larvae are juvenile spat, the larvae are cultured at a density of 100,000 to 1,000,000 larvae / m 2 .

9. The method according to any one of claims 1 to 8, wherein: In the early stage of the floating shell larvae, the amount of bait fed each time makes the bait density in the water body 1*10 4 -4*10 4 cell / mL; In the late stage of shell-top larvae, the amount of bait fed each time makes the bait density in the water body 5*10 4 -8*10 4 cell / mL; During the juvenile stage, the amount of feed added each time makes the feed density in the water body 1*10 5- 1.5*10 5 cell / mL.

10. The method according to claim 1, wherein: The conditions for raising seedlings include: temperature of 25-30°C, salinity of 24-27, pH of 7.8-8.4, and dissolved oxygen of 8 mg / L or more; Preferably, the water used for raising seedlings is secondary sand-filtered seawater.

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