KR20160017436A - Method of inducing metamorphosis of leptocephalus of Japanese eel, Anguilla japonica - Google Patents

Abstract

The present invention relates to a method for inducing a metamorphosis of a leptocephalus of a Japanese eel. More specifically, the method for inducing a metamorphosis of a leptocephalus of a Japanese eel accommodates and raises a leptocephalus which is a larva of a Japanese eel in a water tank, and changes a temperature and a flow rate of breeding water to induce a metamorphosis of the leptocephalus into an elver.

Description

[0001] The present invention relates to a method for inducing metamorphosis of Leptoshephalus,

The present invention relates to a transformation induction method for raising the transformation rate to a false eel and shortening a transformation time when artificially raising Leptosepalus, a Far Eastern eel larva, is raised.

Studies on the production of artificial seeds of Anguilla japonica in the Far East began in the 1960s in Japan, and Yamamoto and Yamauchi (1974) succeeded in breeding hatchlings in the eggs obtained by injection of extrinsic sex hormones and for 2 weeks in the breeding tank Respectively.

However, there was no progress in the related research due to the lack of feeding of the eels. However, in the 2000s, the Tanaka Drug Research Group of the Japan Society for Research on Aquaculture provided a shark-based liquid feed for long-term breeding of leptosepalus, It was the first to produce artificial eel. In addition, European eels,A. anguillaAnd Australian eels,A. dieffenbachia,A. australis And North America,A. rostrata, But there are no reports on the production of artificial eels for the extant species of Far Eastern eel.

In Korea, research on the production of artificial seeds of Far Eastern eels has been started. In 2012, we have succeeded in production of artificial eels through transformation process after rearing of early frog and reptose saplings from embryos produced by artificial sexual induction. However, when artificial rearing of the eel of the Far Eastern eel was carried out, it took more than 200 days to reach the metamorphic stage. In nature, Leptosepalus of the Far Eastern eel reports that metamorphosis occurs about 134-160 days after hatching through analysis of Lee Seok lag, and the period of time and metamorphosis of the eel larvae in nature It depends.

The results of this study are as follows: (1) The effect of the periosteal period on the periosteal period was not statistically significant. of starvation, body size, and temperature on the onset of metamorphosis in Japanese eel ( Anguilla japonica ). Can J Zoology 90, 1378-1385 (2012)). In nature, the Far Eastern Eel ( Anguilla japonica ) is known to spawn in the disintegration of the Mariana trench near 15 ° N, 140 ° E west of Mariana. The hatching larvae were found to be distributed in the eastern part of Taiwan, and were found to be in a transitional state in the limited sea area of 21-26 ° N, 121-129 ° E, east of Taiwan. Observation of the migration route of the Far East eel larvae in the Western Pacific until hatching in the spawning area and transformation into the thread eel was accompanied by the formation of the Kuroshio Current to the north and the Mindanao Current to the south, (Eddy) was noted (Shinoda et al., Evaluation of the Larval Distribution and Migration in the Western Pacific, Rev Fish Biol Fisheries 21, 591-611;

Far Eastern mountain eelAnguilla japonica) Seeds for cultivation were 100% Seed prices are determined according to the amount of eel worms per year due to dependence on natural eel resources. In particular, due to the recent overfishing and climatic changes, the eel wedge rate is expected to decrease to 8,000 won per 1 eels It was called. To solve these problems, we are conducting research on the production of eel artificial seeds around the world.

In Korea, it has been successful to produce artificial eel from Leptosepalus. However, it is necessary to develop artificial rearing method that can increase the transformation rate to Sylvian eel and shorten transformation time and cultivate large amount of eel.

Okamura et al., Effect of starvation, body size, and temperature on the onset of metamorphosis in Japanese eel (Anguilla japonica). Can J Zoology 90, 1378-1385; 2012 Shinoda et al., Evaluation of the larval distribution and migration of the Korean eel in the western North Pacific. Rev Fish Biol Fisheries 21, 591-611; 2011

Therefore, in order to establish the technology for the production of the eel which is necessary for the production technology of the eel artificial seedling, the inventors of the present invention have studied the method of inducing the transformation of the eel of Leptosepalus, the eel of the Far Eastern eel, into the eel of the eel, It was confirmed that the transformation rate and the transformation time vary depending on the water temperature and the flow rate condition of the breeding water in the water tank when the cephalus was contained in the water tank.

It is an object of the present invention to provide a transformation induction method capable of raising the transformation rate to a false eel when artificially raising Leptosepalus, a Far Eastern eel larva, and reducing the time required for transformation.

To this end,

It provides a transformation induction method which induces transformation to a eel by changing the water temperature and flow rate of the rearing water while feeding the reptose caprose, which is the ear of the Far Eastern eel, in the tank.

In the transformation induction method of the present invention, the transformation rate can be increased by forming a vortex in the water tank while maintaining the flow rate of the breeding water supplied to the water tank for the change of the flow rate at 1.0 to 1.4 L / min.

In the transformation induction method of the present invention, the water temperature of the water bath may be maintained at 26 to 27 캜 to shorten the transformation induction time.

In the transformation induction method of the present invention, a vortex in the water tank is formed while maintaining the flow rate of the breeding water supplied to the water tank for changing the flow rate at 1.0 to 1.4 L / min, and the water temperature of the water tank is maintained at 26 to 27 DEG C, And the transformation time can be shortened.

According to the present invention, it is possible to effectively induce metamorphosis into a female eel by changing the water temperature and flow rate while housing the reptose caprose, which is the ear of the Far Eastern eel, in a water tank. Thus, the artificially induced transformation of the eel can be used as an eel artificial seedling.

Fig. 1 schematically shows a breeding aquarium used in the experiment.
Fig. 2 shows the morphological change of the eel of the Far Eastern eel.

Hereinafter, the present invention will be described in detail.

Eels live in rivers and estuaries during the growing season, but they migrate to the sea when they reach the spawning season. The eel that hatches from eggs is almost transparent during migration from the ocean, and its body shape is similar to the shape of bamboo leaves, so it is called Leptosepalus (leptocephalus). This Leptosepalus transforms into a cylindrical eel before reaching the continental shelf. The eel eel that has been transformed in this way is cultivated in nature and is used as eel aquaculture seed.

The present invention proposes a method for efficiently inducing transformation from Leptosepalus, a larval of the Far Eastern eel, to a eel, in order to enable the mass production of eel, which is a cultivar of eel.

To this end, the present invention provides a method of inducing metamorphosis into a female eel by changing the water temperature and flow rate of the breeding water while feeding the reptose caprose, which is the ear of the Far Eastern eel, in a water tank.

The initiation of metamorphosis was induced by abstinence in the leptosepalrus of the Far Eastern eel which was fully artificially grown (over 50mm in length), and the transformation period was accelerated by the increase of the flow velocity and water temperature, and the transformation period was shortened. Therefore, the feed rate is increased during the breeding without feeding the feed and / or water temperature.

At this time, the leptosepalus having a total length of 50 mm or more is used.

The feeding water supplied to the water tank forms eddy in the circular water tank while rotating along a certain direction.

At this time, in order to change the breeding water flow rate in the water tank, the flow rate of the breeding water supplied to the water tank is maintained at 1.0 to 1.4 L / min, preferably 1.2 L / min, which is larger than the flow rate of 0.6 L / The water temperature is maintained at 23 to 24 ° C.

The increase in the flow rate of the breeding water can increase the flow rate in the water tank and increase the transformation rate of the leptosepalus.

Meanwhile, the water temperature of the breeding water is maintained at 26 to 27 DEG C, preferably 26 DEG C, higher than the water temperature of 23 DEG C in the general breeding, and the flow rate of the breeding water supplied to the water tank is maintained at 0.5 to 0.7 L / min.

The temperature of the water in the breeding water can be shortened by the elevated temperature of the leptosepalus.

The " transformation time " referred to in the present invention means the time required to morphologically change from S to S5 in FIG. That is, the time required for the morphological change from S1 to S5 in FIG. 2 was measured based on visual inspection at 10:00 am for 30 days during the test period, and this was regarded as the transformation time.

Also, in order to change the water flow rate in the water tank, the flow rate of the water supplied to the water tank is maintained at 1.0 to 1.4 L / min, preferably 1.2 L / min, larger than the flow rate of 0.6 L / Is maintained at 26 to 27 DEG C, preferably 26 DEG C, higher than the water temperature of 23 DEG C in the general breeding.

The transformation temperature can be increased and the transformation time can be shortened by increasing the water temperature and flow velocity of the breeding water.

Hereinafter, preferred embodiments of the present invention will be described. The following examples are provided for the purpose of more clearly illustrating the present invention and the present invention is not limited to the following examples.

<Preparation Example 1>

1-1. Induction of anthropogenic sexuality by hormone treatment

The female is Kim et al. (Mean body weight 553.1 ± 90.5 g), which was fed with general compound diet for 2.5 years after oral administration of estradiol-17ß orally to male eel stage according to the method described in [2013a] A 1.5 - year old adult (average body weight: 320.2 ± 56.8 g) was used for breeding in the filtration system.

For example, Kim et al. Dihydroxy-4-pregnen-3-one (DHP) was induced by artificial repopulation of salmon pituitary extract (SPE) (Kim et al., 2007a), male transgenic mice were repeatedly injected weekly with human chronic gonadotropin (HCG) to induce matured artificially, And stored at 4 ° C (Kim et al., 2006b)

1-2. Artificial fish production and breeding

The process of artificial insemination and hatching is described in Kim et al. (2007b), and the ears were identified by Tanaka et al. (2001), a modified liquid feed of modified shark egg-based liquid feed, was fed and maintained. Breeding water temperature and flow rate were measured by Tanaka et al. (2001) and Masuda et al. (2011), and maintained at 23 ° C and 0.6 L / min. Individuals with a minimum total length of 50 mm at 200 days after hatching were selected for this experiment (Okamura et al., 2012).

Fig. 1 schematically shows a breeding aquarium used in the experiment. Experimental breeding tanks were treated with an acrylic round tank with a capacity of 10 liters, and water was fed from a water tank set at a constant temperature to a flow meter (TVI-108, NIPPON FLOW (GRT 356E, GILTRON, China) was installed in the experimental water tank to observe the water temperature at all times. The water entering the aquarium was made to form Eddy in a circular water tank according to the flow rate while rotating along a certain direction.

The morphological changes of the metamorphic ears were observed by Kuroki et al. (Maru Sci 34, 31-38 2010) and Okamura et al. (Effect of starvation, body size, and temperature on the onset of metamorphosis in Japanese eel ( Anguilla japonica ), Can J Zoology 90, 1378-1385 (2012)), and from the beginning to the end of the transformation from S1 to S5. In order to investigate the time required for metamorphosis and the rate of transformation of experimental varieties, it was surveyed for 30 days from the date of acceptance.

EXPERIMENTAL EXAMPLE 1: Transformation Induction Effect by Fasting>

In order to investigate the transformation induction effect according to the fasting period, six rabbits were housed in the same two 10 L acrylic round water baths, and the water temperature was 23 ° C. and the flow rate was 0.6 L / min. From the start of the experiment, the feeding tank was stopped and the transformation process was observed. In the feeding tank, shark egg - based liquid feed was observed 5 times a day (5ml / s). The results are shown in Table 1.

Number of test fish
(n) Battlefield
(total length: mm) Body width
(body depth, mm) A transformational day
(duration date of metamorphosis, days) Metamorphosed population
(n) Transformation rate
(%) Fasting experiment 6 53-56 6.8 to 8.3 8-20 5 83.3 Feeding port 6 52-57 6.5 to -8.5 11 to 30 2 33.3

In the fasting experimental group, the individuals transformed into the eel began to appear on the eighth day. Five of the six animals were transformed during the first 20 days of experiment. One animal died during the rearing and the transformation rate was 83.3%. In the feeding zone, only 2 out of 6 birds completed the transformation between 11 and 30 days, showing a transformation rate of 33.3%. In the experimental period, four birds that did not undergo transformation during the experiment were found to have S1 3 and 1 were present.

<Experimental Example 2: Induction effect of transformation by water temperature rise>

In order to investigate the transformation induction effect of the water temperature rise, the flow rate was set to 0.6 L / min, and three fish were housed in two breeding tanks set up at 23 ° C and 23 ° C to 26 ° C. No liquid feed was supplied during the experiment. After that, 3 animals were housed in the same manner and repeated experiments were carried out. Table 2 shows the transformation induction effects in the two experimental groups in which the water temperature was raised to 23 ° C and 26 ° C in a breeding tank adjusted to a flow rate of 0.6 L / min.

flux
(L / min) Water temperature
(° C) Population
(n) Battlefield
(total length: mm) Body width
(body depth, mm) A transformational day
(duration date of metamorphosis, days) Metamorphosed population
(n) Transformation rate
(%) 0.6 23 3 53-56 6.7 to 8.4 0 0 0 0.6 26 3 53-57 7.2 ~ 8.7 7 to 10 2 66.7 0.6 23 3 50 ~ 58 6.2 to 8.7 8-12 3 100 0.6 26 3 50 to -55 7.0 ~ 8.2 8 One 33.3

In the first experiment of the 23 ℃ breeding tank, the transformation was not completed during the experiment period, and there were two animals and one animal of each of S1 and S2 stages of FIG. 2. In the second experiment, all three out of three animals showed metamorphosis between 8 and 12 days and showed 100% transformation rate. Therefore, the average transformation rate of the first and second experimental results was 50%.

On the other hand, in the first experiment of 26 ° C. breeding tank, 2 out of 3 plants were transformed between 7 and 10 days and showed 66.7% transformation rate. The other one did not undergo transformation during the experiment period, Respectively. In the second experiment, 1 out of 3 had completed the transformation on day 8 and showed a transformation rate of 33.3%. The other two did not undergo transformation during the experiment, and the individuals in steps S1 and S3 of Fig. . Therefore, the average transformation rate of the first and second experimental results was 50%.

EXPERIMENTAL EXAMPLE 3: Induction effect of transformation by increase in flow rate (flow rate)

In order to investigate the transformation induced by the increase of the flow rate, the water temperature was set at 23 ° C and three birds were housed in the breeding tanks set at different flow rates of 0.6 L / min and 1.2 L / min. No liquid feed was supplied during the experiment. After that, 3 animals were housed in the same manner and repeated experiments were carried out.

Table 3 shows the results of investigating the transformation induction effect in different breeding conditions at a flow rate of 0.6 L / min and 1.2 L / min in a raising water tank adjusted to a temperature of 23 ° C.

Water temperature
(° C) flux
(L / min) Population
(n) Battlefield
(total length: mm) Body depth (mm) A transformational day
(duration date of metamorphosis, days) Transformation completed population (n) Transformation rate (%) 23 0.6 3 53 ~ 55 7.5 to 8.3 15 One 33.3 23 1.2 3 53-56 7.3 to 8.5 14 2 66.7 23 0.6 3 50 to 54 6.8 to 8.0 8 One 33.3 23 1.2 3 50 to 55 7.0 to -8.2 12 to 22 2 66.7

At the flow rate of 0.6 L / min, only 1 out of 3 specimens showed a transformation rate of 33.3% on the 15th and 8th days of the experiment. However, during the experimental period of the first and second experimental results, each of the two untransformed animals had two S1 and S2 individuals in Fig. 2, and the average transformation rate was 33.3%.

At the flow rate of 1.2 L / min, the transformation was completed by 14 out of the 1st experiment and 2 out of 3 animals between 12 and 22 days in the 2nd experiment. The transformation rate was 66.7%. However, during the experimental period of the first and second experimental results, each of the untransformed animals was observed in Fig. 2 individuals of S2 and S3 were present in each one, and the average transformation rate was 66.7%.

EXPERIMENTAL EXAMPLE 4 Transformation Induced Effect by Flow Rate (Flow Rate)

It was set at 1.2 L / min faster than the normal flow rate and 4 fishes were kept in a water tank set at 26 ℃ and no liquid form feed was supplied during the experiment. After that, 7 animals were housed in the same manner and repeated experiments were conducted.

Table 4 shows the results of investigating the transformation induction effect by raising the water temperature to 26 ° C in the experimental set at a flow rate of 1.2 L / min.

flux
(L / min) Water temperature
(° C) Population
(n) Battlefield
(total length: mm) Body depth (mm) A transformational day
(duration date of metamorphosis, days) Transformation completed population (n) Transformation rate
(%) 1.2 26 4 53-57 7.5 to 8.7 10-12 4 100 1.2 26 7 50 ~ 58 7.0 to 9.1 8 ~ 11 5 71.4

In the first experiment, all of the four birds were completely transformed between 10 and 12 days and 100% transformation rate was obtained. In the second experiment, five out of seven animals were transformed between 8 and 11 days, and two animals that did not undergo transformation during the experimental period had one animal of each of S2 and S3 of FIG. 2, 71.4%. Therefore, the average transformation rate of the first and second experimental results was 85.7%.

Claims (14)

A method of inducing a transformation in a sea eel by changing the water temperature and flow rate of the rearing water while feeding the reptose caprose, which is the ear of the Far Eastern eel, in the tank. The method according to claim 1, wherein the leptosepalus has a total length of 50 mm or more. The method according to claim 1, wherein a vortex is formed in the water tank while maintaining a flow rate of the breeding water supplied to the water tank for changing the flow rate to 1.0 to 1.4 L / min to increase the transformation rate. 4. The method according to claim 3, wherein no feed is fed during the breeding. 4. The method according to claim 3, wherein the water bath is maintained at a temperature of 23 to 24 占 폚. 4. The method according to claim 3, wherein the flow rate is maintained at 1.2 L / min. The method according to claim 1, wherein the water temperature of the water tank is maintained at 26 to 27 캜 to shorten the transformation time. 8. The method according to claim 7, wherein no feed is fed during the breeding. The method according to claim 7, wherein the vortex is formed in the water tank while maintaining the flow rate at 0.5 to 0.7 L / min. The method according to claim 7, wherein the water bath is maintained at a water temperature of 26 캜. 2. The method according to claim 1, wherein a vortex is formed in the water tank while maintaining the flow rate of the breeding water supplied to the water tank for changing the flow rate to 1.0 to 1.4 L / min and the water temperature of the water tank is maintained at 26 to 27 DEG C to increase the transformation rate And the transformation time is shortened. 12. The method according to claim 11, wherein no feed is supplied during the breeding. 12. The method according to claim 11, wherein the flow rate is maintained at 1.2 L / min. The method according to claim 11, wherein the water bath is maintained at a water temperature of 26 ° C.

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