Artificial propagation method for Japanese mackerels and application

Abstract

The invention discloses an artificial propagation method for Japanese mackerels and application, and belongs to the technical field of artificial propagation of fishes. The method comprises the steps of parent breeding, parent spawning induction, fertilized egg collection and incubation, artificial breeding and the like, 186 sexual mature Japanese mackerel parent fishes are successfully bred, more than 300 thousands of fertilized eggs are obtained through natural spawning, 22.9 thousands of larva fishes are hatched, after 20 days of breeding, the average full length of the larva fishes reaches 3.45 cm, the average weight of the larva fishes is 0.33 g, and the larva fishes are normal in development and good in ingestion. The breeding habit of the Japanese mackerel is deeply studied, the problems that the number of parent fishes of the Japanese mackerel is small, the stress response is high, and transportation is difficult are solved, and meanwhile the optimal spawning induction dosage, the required water temperature and other environmental conditions, the fertilized egg incubation condition, the artificial breeding technology and the like of artificial breeding of the Japanese mackerel are mastered.

Description

Technical Field

[0001] The invention belongs to the technical field of fish artificial propagation, and in particular relates to an artificial propagation method for Japanese mackerel and application thereof. Background Art

[0002] Japanese mackerel (Scomber japonicus) belongs to the family Scombridae and the genus Scomber. It is commonly known as bluefish and mackerel. It is widely distributed in the Pacific Ocean, the Atlantic Ocean and its adjacent waters. It is an important small pelagic economic fish in the eastern Yellow Sea of ​​my country. For Japanese mackerel, while strengthening the exploration and development of Japanese mackerel resources, it is very necessary to carry out research on artificial breeding technology and proliferation and release. Reproduction is a key life history process to maintain the continuation of the population. Research on the reproductive biological characteristics of Japanese mackerel can not only provide basic information for population ecology, but also provide basic parameters for its resource quantity and catchable amount assessment, which has a positive effect on protecting offshore resources. Summary of the invention

[0003] To solve the above technical problems, the present invention provides a method and application of artificial propagation of Japanese mackerel. The method includes the steps of parent cultivation, parent induced spawning, fertilized egg collection and hatching, and artificial seedling raising. Using the method in the present invention, 186 sexually mature Japanese mackerel broodstock were successfully cultivated, more than 300,000 fertilized eggs were obtained through natural spawning, and 229,000 fry were hatched. After 20 days of cultivation, the average total length of the fry reached 3.45cm, the average weight was 0.33g, the fry developed normally, and the feeding was good. The present invention has conducted in-depth research on the breeding habits of Japanese mackerel, overcomes the problems of small number of Japanese mackerel broodstock, strong stress response, and difficult transportation, and at the same time grasps the optimal induced spawning dose and required water temperature and other environmental conditions for artificial propagation of Japanese mackerel, as well as fertilized egg hatching conditions and artificial seedling raising technology.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] One of the objects of the present invention is to provide a method for artificial propagation of Japanese mackerel, the method comprising the following steps:

[0006] (1) Parent cultivation: Starting from March, the water temperature is controlled at 20-25℃, the photoperiod is 8-12L:12-16D, oysters and shrimps are selected as bait, and the cultivation period is 0.8-1.2 months;

[0007] (2) Parent induction: After the parent breeding is completed, selection and induction of labor are carried out; the induction agents are HCG and LHRH;

[0008] (3) Fertilized egg collection and incubation: After induction of spawning, the parents are mixed and raised, and the fertilized eggs are collected after the female lays eggs and placed in an incubation bucket with aerated running water for incubation;

[0009] (4) Artificial breeding: After incubation at 24-26℃ for 28-32 hours, most of the fertilized eggs have hatched. At this time, the fry are moved to the nursery pond for breeding. The nursery pond is disinfected in advance. After the fry hatch, they are first fed with ss-type rotifers. On the 4th day after hatching, they are fed with ordinary rotifers. On the 16th day after hatching, they are fed with copepods. After 18-22 days of breeding, when the individuals reach 2.5 cm or more, they can be moved to a larger breeding system for artificial breeding.

[0010] Furthermore, the step (1) also includes a parent selection step, with specific requirements as follows: the fish should be 2-3 years old, weigh between 300-400g, have a normal body shape and strong vitality.

[0011] Furthermore, the step (1) also includes a step of reducing parent stress, specifically: using 0.8-1.2 ml / 500L of eugenol to anesthetize the parent, and the treatment time is controlled within 1 minute.

[0012] Furthermore, in step (1), the ratio of oysters to shrimps is (0.8-1.2): (1.8-2.2), the feeding amount is 4-6% of the fish body weight, and the fish are fed once at 5-7 am and 15-17 pm respectively.

[0013] Furthermore, the selection method in step (2) is as follows: females are selected with enlarged abdomens, and sperm must flow out when the male presses the abdomen; the dosage of oxytocin used for females is HCG 4900-5100 units / kg + LHRH 28-32ug / kg, and the dosage for males is half of that.

[0014] Furthermore, the induction time in step (3) is 7-9 am, the oxytocin action time is 35-36 hours, and the fertilized egg collection time is 38-42 hours after induction of labor.

[0015] Furthermore, the disinfection in step (4) is 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.

[0016] Furthermore, the feeding method of the fry in the step (4) is specifically as follows: first, ss-type rotifers are introduced into the nursery pond at a density of 1 / L, and shrimp flakes and algae powder are fed as bait for the ss rotifers. The fry start to eat after 24-30 hours in the nursery pond, and the ss-type rotifers in the nursery pond are used as the starter bait; on the second day of opening, the feeding amount of the ss-type rotifers is increased, and the density is controlled at 50-100 / L; on the fourth day of opening, the feeding of the ss-type rotifers is stopped, and the common rotifers are started, and the density is controlled at 30-50 / L, and the density is supplemented in time when it is found that the density is reduced; on the 16th day of opening, copepods are started, and they are fed once at 6-8 am and 15-17 pm, and the density is controlled at 5-10 / L.

[0017] Furthermore, the copepods in step (4) are fortified with Schizochytrium and algae powder in advance, and the specific method is: 1 kg of copepods are fortified with Schizochytrium:algae powder in a ratio of 5-15g:45-55g for 30-60 minutes, and then collected for later use.

[0018] The second object of the present invention is to provide application of the method in Japanese mackerel breeding.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) Using the method of the present invention, the present invention team has successfully cultivated 186 sexually mature Japanese mackerel broodstock, obtained more than 300,000 fertilized eggs through natural spawning, and hatched 229,000 fry. After 20 days of cultivation, the average total length of the fry reached 3.45 cm, the average weight was 0.33 g, the fry developed normally, and had good feeding.

[0021] (2) The present invention has conducted an in-depth study on the breeding habits of Japanese mackerel, overcoming the problems of small number of Japanese mackerel broodstock, strong stress response, and difficult transportation. At the same time, the present invention has mastered the optimal induced labor dosage and required water temperature and other environmental conditions for artificial breeding of Japanese mackerel, as well as fertilized egg hatching conditions and artificial seedling breeding technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a comparison picture of Japanese mackerel broodstock and 20-day-old fry in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Without departing from the spirit and essence of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention are within the scope of the present invention. The products, equipment, etc. used in the following examples are commercially available unless otherwise specified, and the methods used are consistent with conventional methods unless otherwise specified.

[0024] The technical solution of the present invention is further described in detail below in conjunction with embodiments.

[0025] Example 1

[0026] This embodiment provides a method for artificial propagation of Japanese mackerel, and the specific steps are as follows:

[0027] (1) Parent cultivation: Parents are selected from individuals with an age of 2-3 years and a weight between 300-400g. They are required to have a normal body shape and strong vitality. They are cultured in indoor factory-scale breeding ponds. Starting from March, the water temperature is controlled at 22℃ and the photoperiod is 10L:14D (light:darkness). The bait is oysters and shrimps, with a ratio of 1:2. The feeding amount is 4-6% of the fish body weight. The specific feeding method is: feed once at 6 am and 16 pm respectively. Feed the bait above the air stone and let it slowly fall to simulate the swimming of live bait. Since the parents are very stress-sensitive, 1ml / 500L of eugenol is used as an anesthetic to reduce their stress ability, and the anesthesia time should be controlled within 1 minute.

[0028] (2) Parental induction of labor: After one month of cultivation and nutritional fortification, select individuals with enlarged abdomens. When pressing the abdomen of males, sperm should flow out. Use HCG (Ningbo Second Hormone Factory, HCG 10,000 units) and LHRH (Ningbo Second Hormone Factory, LHRH-A 50 mg) to induce labor. The dose for females is HCG 5,000 units / kg + LHRH 30 ug / kg, and the dose for males is halved.

[0029] (3) Fertilized egg collection and hatching: Place the induced broodstock in an 80-mesh silk mesh cage. After 40 hours of induced spawning, collect the fertilized eggs and place them in an incubator with aerated water for hatching. Specifically: The induced spawning time is 8 a.m., and the oxytocin effect time is 36 hours. After induced spawning, place the broodstock in the silk mesh cage and wait until midnight the next day (the oxytocin effect time is 40 hours). It can be found that the male individuals are chasing the female individuals, the female individuals are ovulating in the water, and the males are ejaculating for fertilization (in the natural environment, Japanese mackerel spawns at midnight. The induced spawning time is determined by calculating the spawning time).

[0030] (4) Artificial seedling rearing: 25℃, incubate for 30h±2h, and most of the eggs will be found to have hatched. At this time, the fry can be moved to the nursery pond for rearing. The nursery pond should be disinfected with disinfectant (5g / t of strong chlorine) 3 days in advance, and sodium thiosulfate (5g / t) should be used to neutralize the possible residual chlorine in the water 12h before the fry are put in. Then, ss-type rotifers are introduced into the nursery pond at a density of 1 / L, and shrimp flakes and algae powder are fed as bait for ss-type rotifers. The fry start to eat after 24-30 hours in the nursery pond, and ss-type rotifers are used as the first bait for the fry; on the second day of opening, the ss-type rotifers should be fed more in the nursery pond, and the density should be controlled at 50-100 / L; on the fourth day of opening, stop feeding ss-type rotifers and start feeding ordinary rotifers, and control the density at 30-50 / L. If the density is found to be reduced, it will be supplemented in time; on the 16th day of opening, copepods will be fed once at 7 am and 16 pm, and the density will be controlled at 6 / L. Copepods are fortified with schizochytrium and algae powder in advance, specifically: 1kg of copepods are fortified with schizochytrium: algae powder at a ratio of 10g:50g for 30-60min, and then collected and fed. After 20 days of cultivation, when the individuals reach 2.5cm or more, the seedlings can be moved to a larger breeding system for artificial breeding.

[0031] The artificial breeding project of Japanese mackerel has been completed. Using the above method, 186 sexually mature Japanese mackerel broodstock have been successfully cultivated. Through natural spawning, more than 300,000 fertilized eggs have been obtained, and 229,000 fry have been hatched. After 20 days of cultivation, the average total length of the fry reached 3.45cm, the average weight was 0.33g, the fry developed normally, and had good feeding.

[0032] Example 2 Effect of Oxytocin Dosage on Oviposition of Japanese Mackerel (Female)

[0033] The experiment selected healthy and well-developed Japanese mackerel for the study of the determination of the induced labor dosage. 8 dosage combinations were set, 5 Japanese mackerel were induced to spawn in each group, 3 parallels were performed in each group, and the induced labor water temperature was 25°C. The induced Japanese mackerel was placed in a 100-mesh screen. The induced labor effect time was 36 hours. After 40 hours, the screen was checked for spawning, and the spawning amount was weighed (other methods involved were consistent with those in Example 1). The experimental results are shown in Table 1.

[0034] Table 1 Statistics on the number and amount of eggs laid by Japanese mackerel at different induced spawning doses

[0035]

[0036] The results showed that the number and weight of eggs laid by Japanese mackerel were different under different induced labor doses. The worst effect was in the group with 4700 units / kg (HCG) + 25ug / kg (LHRH); the group with the largest number of spawning Japanese mackerel was in the group with 5100 units / kg (HCG) + 30ug / kg (LHRH); the group with the largest total spawning weight was in the group with 5100 units / kg (HCG) + 30ug / kg (LHRH); the group with the largest average spawning amount was in the group with 5100 units / kg (HCG) + 32ug / kg (LHRH); based on the above induced labor results, the appropriate induced labor dose range for Japanese mackerel should be HCG 4900-5100 units / kg, LHRH 28-32ug / kg.

[0037] Example 3 Study on the effect of water temperature on the gonadal development of Japanese mackerel

[0038] Female parents: The test site was set up in a factory workshop, with 5 cement pools of 3m×2m×1.2m for this test, and 18, 20, 23, 25, and 27°C temperature groups were set. The experimental fish used was 200±16g Japanese mackerel, and 10 experimental fish were put into each experimental pool. The cultivation time was 30 days. After the experiment, 6 parents were taken from each temperature group to sample their gonads, and histological preparation was performed to observe the gonadal stage (other methods involved were consistent with those in Example 1). The experimental results are shown in Table 2.

[0039] Table 2 Effects of different temperatures on the development of female gonads of Japanese mackerel

[0040]

[0041] 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 gonads of Japanese mackerel developed to stage IV and could be used for artificial induction of spawning; at 27℃, most of the gonads of Japanese mackerel had degenerated. Therefore, in the cultivation of female parents, the cultivation temperature should be controlled at 20-25℃.

[0042] Male parent: The experimental breeding pond is 3m×2m×1.2m in size, and different temperature groups of 18, 20, 23, 25, and 27°C are set, and 3 parallel groups are set. The experimental fish is 300±27g Japanese mackerel, and 5 male experimental fish are put into each experimental pond. Before the experiment, it is checked that all male Japanese mackerel can squeeze out sperm, and the cultivation time is 30 days. After the experiment, check whether the male can squeeze out sperm, and test the sperm quality (other methods involved are consistent with those in Example 1). The experimental results are shown in Table 3.

[0043] Table 3 Effects of different temperatures on male Japanese mackerel

[0044]

[0045]

[0046] The results showed that after 30 days of cultivation, temperature had a significant effect on whether male Japanese mackerel could produce sperm and sperm motility. At 18°C, only two male parents could produce sperm, one of which had sperm motility within 1 minute, and another had sperm motility within 2 minutes; at 20°C, 23°C and 25°C, male Japanese mackerel could maintain sperm production, and sperm motility was good, with more than 80% of individual sperm motility greater than 1 minute; at 27°C, the number of sperm that male Japanese mackerel could produce was significantly reduced, and sperm motility was not as good as in other experimental groups. This shows that the optimal culture temperature for male Japanese mackerel is 20°C to 25°C. :

[0047] Example 4 Study on the Effect of Photoperiod on the Gonadal Index of Japanese Mackerel

[0048] High-power full-spectrum LED lamps are set above the culture pond to simulate the effects of different photoperiods on the gonadal development of Japanese mackerel under natural light conditions. The photoperiod is designed to be 16L:8D, 14L:10D, 12L:12D, 10L:14D, 8L:16D, a total of 5 photoperiods, 3 repetitions are set for each photoperiod, and each repetition is 6 Japanese mackerel parents, and the water temperature is maintained at 23-24°C, and dissolved oxygen is maintained at more than 6mg / L. After the experiment, the experimental fish body mass is measured, the gonads are dissected and weighed, the gonad index is calculated, and the experimental results (other involved methods are consistent with those in Example 1) are statistically analyzed. The results are shown in Table 4.

[0049] Table 4 Effects of different photoperiods on gonadal index of Japanese mackerel parents

[0050]

[0051] The results showed that the group with the largest number of gonadal indexes (GSI < 1) was the 16L:8D group, and the group with the smallest number was the 10L:14D group. The group with the largest number of gonadal indexes (GSI ≥ 3) was the 10L:14D group, and the group with the smallest number was the 16L:8D group. The order of the number of gonadal indexes (GSI ≥ 1) of Japanese mackerel under each photoperiod was: 10L:14D > 12L:12D > 8L:16D > 14L:10D > 16L:8D. Therefore, in the process of artificial breeding, the photoperiod of 8L:16D, 10L:14D or 12L:12D should be selected for the breeding of Japanese mackerel parents.

[0052] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for artificial propagation of Japanese mackerel, characterized in that: The following steps are involved: (1) Parent cultivation: Starting from March, the water temperature is controlled at 20-25℃, the photoperiod is 8-12L:12-16D, oysters and shrimps are selected as bait, and the cultivation period is 0.8-1.2 months; (2) Parent induction: After the parent breeding is completed, selection and induction of labor are carried out; the induction agents are HCG and LHRH; (3) Fertilized egg collection and incubation: After induction of spawning, the parents are mixed and raised, and the fertilized eggs are collected after the female lays eggs and placed in an incubation bucket with aerated running water for incubation; (4) Artificial breeding: After incubation at 24-26℃ for 28-32 hours, most of the fertilized eggs have hatched. At this time, the fry are moved to the nursery pond for breeding. The nursery pond is disinfected in advance. After the fry hatch, they are first fed with ss-type rotifers. On the 4th day after hatching, they are fed with ordinary rotifers. On the 16th day after hatching, they are fed with copepods. After 18-22 days of breeding, when the individuals reach 2.5 cm or more, they can be moved to a larger breeding system for artificial breeding.

2. The artificial propagation method of Japanese mackerel according to claim 1, characterized in that The step (1) also includes a parent selection step, with specific requirements as follows: the fish should be 2-3 years old, weigh between 300-400g, have a normal body shape and strong vitality.

3. The artificial propagation method of Japanese mackerel according to claim 2, characterized in that The step (1) also includes a step of reducing parent stress, specifically: using 0.8-1.2 ml / 500L of eugenol to anesthetize the parent, and the treatment time is controlled within 1 minute.

4. The artificial propagation method of Japanese mackerel according to claim 3, characterized in that: In the step (1), the ratio of oysters to shrimps is (0.8-1.2): (1.8-2.2), and the feeding amount is 4-6% of the fish body weight, and the fish are fed once at 5-7 am and 15-17 pm respectively.

5. The artificial propagation method of Japanese mackerel according to claim 4, characterized in that: The selection method in step (2) is as follows: females are selected with enlarged abdomens, and sperm must flow out when the abdomen is pressed by males; the dosage of oxytocin used for females is HCG 4900-5100 units / kg + LHRH 28-32ug / kg, and the dosage for males is half of that.

6. The artificial propagation method of Japanese mackerel according to claim 5, characterized in that: The induction time in step (3) is 7-9 am, the oxytocic agent takes effect for 35-36 hours, and the fertilized egg collection time is 38-42 hours after induction of labor.

7. The artificial propagation method of Japanese mackerel according to claim 6, characterized in that: The disinfection in step (4) is 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.

8. The artificial propagation method of Japanese mackerel according to claim 7, characterized in that: The feeding method of the fry in the step (4) is specifically as follows: firstly, ss-type rotifers are introduced into the nursery pond at a density of 1 per liter, and shrimp flakes and algae powder are fed as bait for the ss-type rotifers. The fry start to eat after 24-30 hours in the nursery pond, and the ss-type rotifers in the nursery pond are used as the starter bait; on the second day of the starter, the feeding amount of the ss-type rotifers is increased, and the density is controlled at 50-100 per liter; on the fourth day of the starter, the feeding of the ss-type rotifers is stopped, and the common rotifers are started, and the density is controlled at 30-50 per liter, and the density is supplemented in time when it is found that the density is reduced; on the 16th day of the starter, copepods are started to be fed, and the feed is fed once at 6-8 am and 15-17 pm, and the density is controlled at 5-10 per liter.

9. The artificial propagation method of Japanese mackerel according to claim 8, characterized in that: The copepods in step (4) must be fortified with Schizochytrium and algae powder in advance. The specific method is: 1 kg of copepods are fortified with Schizochytrium:algae powder in a ratio of 5-15g:45-55g for 30-60 minutes, and then collected for later use.

10. Use of the artificial propagation method of Japanese mackerel according to any one of claims 1 to 9 in breeding Japanese mackerel.

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