Method for artificial propagation of scomber japonicus and application thereof

Abstract

The application discloses a method for artificially breeding Japanese scomber and application, and belongs to the technical field of artificial fish breeding. The method comprises the steps of parent cultivation, parent induced delivery, fertilized egg collection and hatching, and artificial breeding, 186 sexually mature Japanese scomber parent fishes are successfully cultivated, more than 300,000 fertilized eggs are obtained through natural spawning, 229,000 fry are hatched, after 20 days of cultivation, the average total length of the fry reaches 3.45 cm, the average weight is 0.33 g, the fry develops normally, and the feeding is good. The application has carried out in-depth research on the breeding habit of Japanese scomber, overcomes the problems of few Japanese scomber parent fishes, strong stress response and difficult transportation, and simultaneously masters the best induced delivery dose of artificial breeding of Japanese scomber, required water temperature and other environmental conditions, fertilized egg hatching conditions and artificial breeding technology and the like.

Description

Technical Field

[0001] This invention belongs to the field of fish artificial breeding technology, and particularly relates to a method and application for artificial breeding of Japanese mackerel. Background Technology

[0002] Japanese mackerel (Scomber j) aponicus The Japanese mackerel (Scoprinus japonicus) belongs to the family Scombridae and the genus Scombridae. Commonly known as mackerel or tuna, it is widely distributed in the Pacific, Atlantic, and adjacent waters and is an important small, mid-to-upper-level economic fish in the East China Sea and Yellow Sea of ​​my country. For the Japanese mackerel, while strengthening the exploration and development of its resources, it is essential to conduct research on artificial breeding techniques and stock enhancement. Reproduction is a key life history process for maintaining population continuity. Research on the reproductive biological characteristics of the Japanese mackerel can not only provide basic information for population ecology but also provide basic parameters for assessing its resource quantity and catchable population, which plays a positive role in protecting nearshore resources. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method and application for the artificial breeding of Japanese mackerel. The method includes steps such as broodstock rearing, broodstock spawning induction, fertilized egg collection and hatching, and artificial seedling cultivation. Using the method of this invention, 186 sexually mature Japanese mackerel broodstock were successfully bred, yielding over 300,000 fertilized eggs through natural spawning, resulting in 229,000 fry. After 20 days of rearing, the fry reached an average total length of 3.45 cm and an average weight of 0.33 g, exhibiting normal development and good feeding. This invention provides an in-depth study of the reproductive habits of Japanese mackerel, overcoming the problems of low broodstock numbers, strong stress responses, and difficult transportation. It also establishes the optimal spawning induction dosage, required water temperature, and other environmental conditions for artificial breeding of Japanese mackerel, as well as the hatching conditions for fertilized eggs and artificial seedling cultivation techniques.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: One objective of this invention is to provide a method for the artificial breeding of Japanese mackerel, the method comprising the following steps: (1) Parent breeding: Starting in March, the water temperature is controlled at 20-25 ℃, the photoperiod is 8-12 L: 12-16 D, the feed is oysters and shrimp, and the breeding period is 0.8-1.2 months; (2) Parental induction of labor: After the parental breeding is completed, selection and labor induction are carried out; the labor induction agents are HCG and LHRH; (3) Collection and hatching of fertilized eggs: After induced spawning, the parents are mixed and cultured. After the females lay eggs, the fertilized eggs are collected and placed in an incubation tank with air and water for incubation. (4) Artificial breeding: After incubation at 24-26 ℃ for 28-32 h, most of the fertilized eggs will have hatched. At this time, the fry will be transferred to the breeding pond for cultivation. The breeding pond should be disinfected in advance. After the fry start to eat, they should be fed with SS-type rotifers first. On the 4th day after they start eating, they should be fed with ordinary rotifers. On the 16th day after they start eating, they should be fed with copepods. After 18-22 days of cultivation, when the individuals reach 2.5 cm or more, they can be transferred to a larger breeding system for artificial breeding.

[0005] Furthermore, step (1) also includes a parent selection step, specifically requiring that the fish be 2-3 years old, weigh between 300-400 g, have normal body shape, and be vigorous.

[0006] Furthermore, step (1) also includes a step to reduce parental stress, specifically: anesthetizing the parental parent with 0.8-1.2 ml / 500L of eugenol for a duration of less than 1 minute.

[0007] Furthermore, in step (1), the ratio of oysters to shrimp is (0.8-1.2):(1.8-2.2), and the feeding amount is 4-6% of the fish's body weight, fed once each at 5-7 am and 3-5 pm.

[0008] Furthermore, the selection method in step (2) is as follows: females are selected from individuals with swollen abdomens, and males should be able to expel sperm when pressing their abdomens; the dosage of oxytocin used for females is 4900-5100 units / kg of HCG + 28-32 ug / kg of LHRH, and half that for males.

[0009] Furthermore, the induction time in step (3) is 7-9 am, the duration of the oxytocin effect is 35-36 h, and the collection time of the fertilized eggs is 38-42 h after induction.

[0010] Furthermore, the disinfection in step (4) should be completed 2-4 days in advance, using 4-6 g / t of strong chlorine, and attention should be paid to neutralizing any residual chlorine that may be present.

[0011] Furthermore, the feeding method for fry in step (4) is as follows: First, introduce SS-type rotifers into the nursery pond at a density of 1 rotifer / L, and feed them shrimp chips and algae powder as SS-type rotifer feed. The fry will start feeding 24-30 hours after entering the nursery pond, and at this time, the SS-type rotifers in the nursery pond will be used as the initial feed. On the second day after entering the nursery pond, increase the amount of SS-type rotifers fed, and control the density at 50-100 rotifers / L. On the fourth day after entering the nursery pond, stop feeding SS-type rotifers and start feeding ordinary rotifers, and control the density at 30-50 rotifers / L. If the density decreases, replenish it in time. On the 16th day after entering the nursery pond, start feeding copepods, feeding once each at 6-8 am and 3-5 pm, and control the density at 5-10 rotifers / L.

[0012] Furthermore, in step (4), the copepods need to be pre-strengthened with Schizochytrium and algal powder. The specific method is as follows: 1 kg of copepods are strengthened with Schizochytrium and algal powder at a ratio of 5-15 g: 45-55 g for 30-60 min, and then collected for later use.

[0013] The second objective of this invention is to provide the application of the method in the breeding of Japanese mackerel.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) Using the method in this invention, the team has successfully bred 186 sexually mature Japanese mackerel parent fish, obtained more than 300,000 fertilized eggs through natural spawning, and hatched 229,000 fry. After 20 days of cultivation, the fry reached an average total length of 3.45 cm and an average weight of 0.33 g. The fry developed normally and fed well.

[0015] (2) This invention has conducted in-depth research on the breeding habits of Japanese mackerel, overcome the problems of small number of Japanese mackerel parent fish, strong stress response and difficulty in transportation, and has mastered the optimal spawning dosage and environmental conditions such as required water temperature for artificial breeding of Japanese mackerel, as well as the hatching conditions of fertilized eggs and artificial seedling technology. Attached Figure Description

[0016] Figure 1 These are comparison images of Japanese mackerel parent fish and juvenile fish raised for 20 days, as shown in Example 1 of this invention. Detailed Implementation

[0017] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the invention. Unless otherwise specified, the products and equipment used in the following embodiments are commercially available, and the methods used are consistent with conventional methods unless otherwise specified.

[0018] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0019] Example 1 This embodiment provides a method for the artificial breeding of Japanese mackerel, the specific steps of which are as follows: (1) Broodstock rearing: Broodstock were selected from individuals aged 2-3 years, weighing between 300-400 g, with normal body shape and strong vitality. They were reared in indoor factory-style aquaculture ponds starting in March, with the water temperature controlled at 22 ℃ and a photoperiod of 10L:14D (light:dark). The diet consisted of oysters and shrimp in a 1:2 ratio, with a feeding amount of 4-6% of the fish's body weight. The specific feeding method was to feed twice a day, at 6:00 AM and 4:00 PM, placing the feed above the airstone and allowing it to slowly descend, simulating the movement of live food. Because the broodstock were highly irritable, 1 ml / 500L of eugenol was used as an anesthetic to reduce their stress, and the anesthesia time was controlled within 1 minute.

[0020] (2) Induction of spawning in parents: After one month of cultivation and nutritional fortification, individuals with swollen abdomens were selected, and sperm should flow out when the abdomen of the male was pressed. Spawning was induced using HCG (Ningbo Second Hormone Factory, HCG 10000 units) and LHRH (Ningbo Second Hormone Factory, LHRH-A 50mg). The dosage for females was 5000 units / kg of HCG + 30 ug / kg of LHRH, and the dosage for males was halved.

[0021] (3) Collection and hatching of fertilized eggs: The induced spawning parent fish are placed in an 80-mesh silk screen cage. After 40 hours of induced spawning, the fertilized eggs are collected and placed in an incubation tank with airflow and water flow for hatching. Specifically: The induced spawning time is selected at 8:00 AM, and the induced spawning agent has an effect time of 36 hours. After induced spawning, the parent fish are placed in a silk screen cage. By 24:00 the next night (the induced spawning agent effect time is 40 hours), male individuals can be seen chasing female individuals. Female individuals lay eggs in the water, and males release sperm for fertilization (in the natural environment, Japanese mackerel spawn at midnight. The induced spawning time is determined by calculating the spawning time).

[0022] (4) Artificial breeding: At 25 ℃, after 30 h ± 2 h of incubation, most of the eggs will have hatched. At this time, the fry can be transferred to the breeding pond for further cultivation. The breeding pond should be disinfected with disinfectant water (5 g / t of strong chlorine) 3 days in advance. Sodium thiosulfate (5 g / t) should be used to neutralize any residual chlorine in the water 12 h before the fry are introduced. Then, SS-type rotifers should be introduced into the breeding pond at a density of 1 rotifer / L. Shrimp chips and algae powder should be fed as feed for the SS-type rotifers. The fry begin feeding 24-30 hours after being placed in the nursery pond, with SS-type rotifers serving as their initial food. On the second day after feeding, the density of SS-type rotifers should be increased in the nursery pond, maintaining a density of 50-100 rotifers / L. On the fourth day after feeding, SS-type rotifer feeding should be stopped, and ordinary rotifers should be introduced, maintaining a density of 30-50 rotifers / L. Supplementation should be made promptly if the density decreases. On the 16th day after feeding, copepods should be introduced, twice a day at 7:00 AM and 4:00 PM, maintaining a density of 6 copepods / L. The copepods are pre-enriched with *Schizochytrium* and algal powder, specifically: 1 kg of copepods are enriched with *Schizochytrium* and algal powder at a ratio of 10 g: 50 g for 30-60 minutes, then collected and fed. After 20 days of rearing, when the individuals reach 2.5 cm or larger, the fry can be transferred to a larger aquaculture system for artificial rearing.

[0023] The aforementioned artificial breeding project for Japanese mackerel has been completed. Using the above methods, 186 sexually mature Japanese mackerel parent fish were successfully bred. Through natural spawning, more than 300,000 fertilized eggs were obtained, and 229,000 fry hatched. After 20 days of rearing, the fry reached an average total length of 3.45 cm and an average weight of 0.33 g. The fry developed normally and fed well.

[0024] Example 2: Effect of oxytocin dosage on spawning in female Japanese mackerel. Healthy, well-developed Japanese mackerel were selected for the study of determining the spawning-inducing dosage. Eight dosage combinations were set up, with five Japanese mackerel spawning in each group, and three replicates per group. The spawning-inducing water temperature was 25 ℃. The spawning-inducing Japanese mackerel were placed in a 100-mesh silk screen. The spawning-inducing effect lasted for 36 hours. After 40 hours, the presence of eggs in the silk screen was checked, and the number of eggs was weighed (other methods involved were consistent with those in Example 1). The experimental results are shown in Table 1.

[0025] Table 1. Statistics on the number of eggs laid and the number of eggs laid by Japanese mackerel under different spawning stimulant doses.

[0026] The results showed that different spawning induced doses resulted in variations in the number and weight of spawns in Japanese mackerel. The worst-performing dose group was 4700 IU / kg (HCG) + 25 ug / kg (LHRH); the group with the highest number of spawns was 5100 IU / kg (HCG) + 30 ug / kg (LHRH); the group with the highest total spawn weight was 5100 IU / kg (HCG) + 30 ug / kg (LHRH); and the group with the highest average spawning volume was 5100 IU / kg (HCG) + 32 ug / kg (LHRH). Based on these results, the appropriate spawning induced dose range for Japanese mackerel is 4900-5100 IU / kg HCG and 28-32 ug / kg LHRH.

[0027] Example 3: Study on the effect of water temperature on gonadal development of Japanese mackerel Female broodstock: The experimental site was set up in a factory workshop, with five 3m×2m×1.2m cement pools used for this experiment, and temperature groups of 18, 20, 23, 25, and 27℃ were set up. Japanese mackerel weighing 200±16g were used as experimental fish, with 10 fish stocked in each pool. The rearing period was 30 days. After the experiment, gonads of 6 broodstock from each temperature group were collected and histological sections were prepared to observe gonadal stage (other methods involved were consistent with those in Example 1). The experimental results are shown in Table 2.

[0028] Table 2. Effects of different temperatures on gonadal development in female Japanese mackerel.

[0029] The results showed that at 18℃, most of the gonads of Japanese mackerel remained at stage II; at 20℃, 23℃, and 25℃, more than 50% of the individuals had gonads developed to stage IV, which could be used for artificial spawning; at 27℃, most of the gonads of Japanese mackerel had degenerated. Therefore, in the breeding of female broodstock, the breeding temperature should be controlled at 20-25℃.

[0030] Male broodstock: The experimental rearing ponds were 3m × 2m × 1.2m in size, with different temperature groups of 18, 20, 23, 25, and 27℃, and three parallel groups were set up. Japanese mackerel weighing 300±27g were used as experimental fish, and five male experimental fish were placed in each pond. Before the experiment, sperm could be extracted from all male Japanese mackerel. The rearing period was 30 days. After the experiment, the ability to extract sperm from the males was checked, and sperm quality was tested (other methods were consistent with those in Example 1). The experimental results are shown in Table 3.

[0031] Table 3 Effects of different temperatures on male Japanese mackerel

[0032] The results showed that after 30 days of cultivation, temperature significantly affected the sperm production and motility of male Japanese mackerel. At 18℃, only two male parents produced sperm, with one producing sperm within 1 minute and the other within 2 minutes. At 20℃, 23℃, and 25℃, male Japanese mackerel maintained sperm production with good motility, with over 80% of individuals showing motility greater than 1 minute. At 27℃, the number of sperm produced by male Japanese mackerel decreased significantly, and sperm motility was also lower than in other experimental groups. This indicates that the optimal culture temperature for male Japanese mackerel is 20℃ to 25℃. Example 4: Study on the effect of photoperiod on the gonadal index of Japanese mackerel High-power full-spectrum LED lights were installed above the rearing ponds to simulate the effect of different photoperiods on the gonad development of Japanese mackerel under natural light conditions. The photoperiods were designed as follows: 16L:8D, 14L:10D, 12L:12D, 10L:14D, and 8L:16D, for a total of five photoperiods. Three replicates were set up for each photoperiod, with each replicate consisting of six Japanese mackerel broodstock. The rearing water temperature was maintained at 23–24℃, and dissolved oxygen was maintained above 6 mg / L. After the experiment, the body weight of the experimental fish was measured, the gonads were dissected and weighed, the gonad index was calculated, and the experimental results were statistically analyzed (other methods involved were consistent with those in Example 1). The results are shown in Table 4.

[0033] Table 4. Effects of different photoperiods on the gonad index of Japanese mackerel parents

[0034] The results showed that the 16L:8D group had the highest number of gonadal indices (GSI < 1), while the 10L:14D group had the lowest. Conversely, the 10L:14D group had the highest number of gonadal indices (GSI ≥ 3), while the 16L:8D group had the lowest. The order of the number of Japanese mackerel gonadal indices (GSI ≥ 1) under different photoperiods was: 10L:14D > 12L:12D > 8L:16D > 14L:10D > 16L:8D. Therefore, in the artificial breeding process, the photoperiods of 8L:16D, 10L:14D, or 12L:12D should be selected for the rearing of Japanese mackerel broodstock.

[0035] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for artificially breeding Japanese mackerel, characterized in that, Includes the following steps: (1) Parent breeding: Starting in March, the water temperature is controlled at 20-25 ℃, the photoperiod is 8-12 L: 12-16 D, the feed is oysters and shrimp, and the breeding period is 0.8-1.2 months; (2) Parental spawning induction: After the parental breeding is completed, selection and spawning induction are carried out; the spawning induction agents are HCG and LHRH; the selection method is as follows: females are selected for their swollen abdomens, and males should be selected for their abdomens when pressed to produce sperm; the dosage of spawning induction agents for females is 4900-5100 units / kg of HCG + 28-32 ug / kg of LHRH, and half the dosage for males; the spawning induction time is 7-9 am, the spawning induction time is 35-36 h, and the fertilized eggs are collected 38-42 h after spawning induction; (3) Collection and hatching of fertilized eggs: After induced spawning, the parents are mixed and cultured. After the females lay eggs, the fertilized eggs are collected and placed in an incubation tank with air and water for incubation. (4) Artificial breeding: After incubation at 24-26 ℃ for 28-32 h, most of the fertilized eggs will have hatched. At this time, the fry will be transferred to the breeding pond for cultivation. The breeding pond should be disinfected in advance. After the fry start to eat, they should be fed with SS-type rotifers first. On the 4th day after they start eating, they should be fed with ordinary rotifers. On the 16th day after they start eating, they should be fed with copepods. After 18-22 days of cultivation, when the individuals reach 2.5 cm or more, they can be transferred to a larger breeding system for artificial breeding.

2. The method for artificially breeding Japanese mackerel according to claim 1, characterized in that, Step (1) also includes the step of parent selection, with specific requirements as follows: fish age 2-3 years, weight between 300-400 g, normal body shape, and strong vitality.

3. The method for artificially breeding Japanese mackerel according to claim 2, characterized in that, Step (1) also includes a step to reduce parental stress, specifically: anesthetizing the parental parent with 0.8-1.2 ml / 500L of eugenol for a duration of less than 1 minute.

4. The method for artificially breeding Japanese mackerel according to claim 3, characterized in that, In step (1), the ratio of oysters to shrimp is (0.8-1.2):(1.8-2.2), and the feeding amount is 4-6% of the fish's body weight, fed once each at 5-7 am and 3-5 pm.

5. The method for artificially breeding Japanese mackerel according to claim 4, characterized in that, The disinfection in step (4) should be completed 2-4 days in advance, using 4-6 g / t of strong chlorine, and attention should also be paid to neutralizing any residual chlorine.

6. The method for artificially breeding Japanese mackerel according to claim 5, characterized in that, The specific method for feeding fry in step (4) is as follows: First, introduce SS-type rotifers into the nursery pond at a density of 1 rotifer / L, and feed them shrimp chips and algae powder as SS-type rotifer feed. The fry will start feeding 24-30 hours after entering the nursery pond, and at this time, the SS-type rotifers in the nursery pond will be used as the first feed. On the second day after entering the nursery pond, increase the amount of SS-type rotifers fed, and control the density at 50-100 rotifers / L. On the fourth day after entering the nursery pond, stop feeding SS-type rotifers and start feeding ordinary rotifers, and control the density at 30-50 rotifers / L. If the density decreases, replenish it in time. On the 16th day after entering the nursery pond, start feeding copepods, feeding once each at 6-8 am and 3-5 pm, and control the density at 5-10 rotifers / L.

7. The method for artificially breeding Japanese mackerel according to claim 6, characterized in that, In step (4), the copepods need to be pre-strengthened with Schizochytrium and algal powder. The specific method is as follows: 1 kg of copepods are strengthened with Schizochytrium and algal powder at a ratio of 5-15 g: 45-55 g for 30-60 min, and then collected for later use.

8. The application of the artificial breeding method for Japanese mackerel according to any one of claims 1-7 in the breeding of Japanese mackerel.

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