JP2008237089A - Method for managing artificial seed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for managing artificial seeds in the production of the artificial seeds, accelerating the growth of them and providing efficiency and stabilization of the production of the artificial seeds by managing the growing water having an appropriate salt concentration in accordance with the kinds, properties and growing stages of the seeds i.e., fertilized eggs, fries or larvae to activate their physiological functions. <P>SOLUTION: This method for managing the artificial seeds the production of the artificial seeds, when hatching the fertilized eggs, growing the seeds of marine fishes or migrating fishes or larvae of shell fishes, forming salt gradient layers in the growing water in an aquarium, hatching eggs by floating the fertilized eggs in a region having a salt concentration fitting with the specific gravity of the egg in the aquarium, and also growing the seeds or larvae; while selecting the salt concentration in accordance with the kinds, properties or growing stages of them. Especially, it is suitable for the growth management of the fries of coast-living marine fishes or downstream-migrating fishes. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for managing artificial seedlings. More specifically, the present invention relates to a method of hatching fertilized eggs or rearing marine or migratory larvae and crustacean larvae in artificial seedling production of aquatic products. The “seed seedling” in the aquaculture business is a general term for young individuals such as eggs, larvae, and larvae of the animals to be started (New Fisheries Handbook).

  In general, the salinity of the ocean is not constant, and fish and crustaceans have the optimum salinity for hatching and inhabiting, and they are hatched and inhabited in their own salinity. It is known that In addition, larvae and larvae have many species whose proper salinity changes as they grow. However, conventionally, hatching of fertilized eggs and rearing of larvae or larvae in artificial seedling production are different from natural sea areas, and the salinity in the rearing water is constant, and fertilized eggs that are reared and larvae that are reared ( It is carried out in an environment where it is not possible to select water areas with appropriate salinity for each of (bred larvae) and larvae (bred larvae). However, in artificial seedling production in which fertilized eggs are hatched in large quantities and larvae and larvae are bred in large quantities, it is difficult to manage the salinity concentration of the breeding water according to the characteristics of individual seedlings and the growth stage.

  In addition, in the management of fertilized eggs in artificial seedling production, most fertilized eggs float on the surface of the water and stay on the surface of the breeding water, and are exposed to ultraviolet rays and outside air, and are hatched, survival rate or This has affected the sluggishness of early survival such as malformation rate.

  In addition, the decline in the early survival rate of larvae and larvae is due to specific pathogenic organisms such as bacteria and parasites, and the breeding water environment is not actually suitable for larvae and larvae. Since it is often due to a physiological disorder resulting from stress such as pressure regulation, it is necessary to mitigate this stress in order to improve the survival rate of larvae and larvae.

From such circumstances, the present inventor aims to improve the breeding water in artificial seedling production and improve the productivity of seedlings, hatch fertilized eggs using breeding water of various salt concentrations, Raised and studied larvae and larvae. In addition, it has been said that "fry fish gather in the estuary area", and because the movement of fish is active in the breeding water where the salinity is thinner than seawater, the salinity of the breeding water is reduced. The idea of changing the larvae and larvae according to the growth stage of the larvae and larvae, and further testing and research, is that when a salt leaping layer (water area with a salinity gradient) is established in the aquarium, the larvae and larvae are found in the climax layer. I noticed that fertilized eggs gathered and completed the present invention. In addition, this inventor has detected the following gazettes as a result of investigating patent documents.
JP 2006-288234 A JP 7-67495 A Report of 2006 1st Annual Meeting of the Fisheries Science Society of Japan Fisheries Prosperity Meeting “Current Status and Prospects of Artificial Seedlings for Aquaculture” (October 7, 2006)

  In patent document 1, when breeding marine fish larvae and juveniles by the artificial seedling production method, dilute seawater treatment (low salinity treatment) is performed by adding fresh water to the breeding water, and low salinity is maintained for a certain period of time. Then, an anti-morbid breeding method for returning to the whole seawater is disclosed. In this document, it is unclear whether or not a salinity gradient is formed in the low salinity breeding water to which fresh water is added, but it is expressed as “diluted seawater treatment (low salinity treatment)”. It is considered that seawater with a constant salt concentration was added and stirred. This document also shows that breeding in diluted seawater for a certain period of time is effective for the survival of ill-skilled fry, such as `` moribund oniokose larvae '', that is, effective for healing and recovery of diseased fish. However, it does not indicate that it is effective in relieving stress and improving anti-morbidity of healthy larvae.

  Further, in Patent Document 2, a fishway having a salinity concentration gradient is installed near the mouth of a river, and migratory fish that run up the mother river has a salinity concentration by adjusting the salinity concentration of brackish water in the channel. Disclosed is a method for increasing the rate of migratory fish ascending by making it easy to cope with changes, and a fishway device used therefor. In this method, weirs are conventionally provided in brackish water areas where fresh water and seawater are mixed, such as estuaries, creating a boundary line of salinity, making it difficult for migratory adult fish to adjust the body to a drastic decrease in salinity. So it was considered as a solution. Therefore, Patent Document 2 has no description regarding a method for raising a salt concentration gradient in the breeding water to breed larvae and larvae in the aquarium or to hatch fertilized eggs.

  Non-Patent Document 1 is a report summarizing the latest technical information on the current state of artificial seedlings for aquaculture. However, a salinity layer is provided in the breeding water to raise larvae and larvae, There is no mention of a method for hatching fertilized eggs by providing a fertilizer.

  In view of the above situation, in the artificial seedling production, the present invention manages the seedlings, i.e., fertilized eggs, larvae and larvae, by managing them with breeding water having an appropriate salt concentration according to the type, properties and growth stage. The purpose is to promote the growth of seedlings and promote the growth of seedlings, thereby improving the efficiency and stabilization of artificial seedling production.

  Among the inventions for solving the above-mentioned problems, the invention described in claims 1 and 2 is that in the production of artificial seedlings, when raising marine fish, migratory larvae or crustacean larvae, An artificial seedling management method characterized by forming a salt-climbing layer in breeding water and breeding larvae or larvae while selecting their own appropriate salt concentration in the aquarium.

  In addition, in the artificial seedling production, when the fertilized egg is hatched, the invention described in claim 2 forms a salt concentration layer in the breeding water in the aquarium, and the fertilized egg is adapted to its specific gravity in the aquarium. It is a management method of artificial seedlings characterized by floating in a salinity range and hatching.

  Similarly, the invention described in claim 3 is the management method according to claim 1, in which seawater is the lower layer, and salt water or fresh water having a concentration according to the type, character, and growth stage of the larvae or larvae is the upper layer. This is a method for managing artificial seedlings in which a salt-cracking layer is formed and larvae or larvae are bred using the breeding water.

  Similarly, the invention described in claim 4 is the management method according to claim 2, wherein the seawater is used as a lower layer, and salt water or fresh water having a concentration according to the type, properties, and growth stage of a fertilized egg is used as a salt layer. It is a management method of artificial seedlings that form a layer and hatch fertilized eggs using the breeding water.

  Further, the invention according to claim 5 is the management method according to claim 3, wherein the larvae or larvae of marine fish such as black sea bream, flounder, okoze, etc. are used in the management method according to claim 3, wherein the breeding water is a salt water having a lower concentration than seawater. It is a management method of artificial seedlings for raising crustacean larvae such as king crab, tiger prawn and crab.

  Further, the invention described in claim 6 is the management method according to claim 3, wherein the management of the artificial seedling for raising migratory fish such as sweetfish, salmon, trout, etc., using fresh water as the upper layer Is the method.

  According to the method for managing artificial seedlings according to the present invention, when breeding larvae and larvae, the salt concentration in the breeding water is not subtly adjusted at the site of seedling production by forming a salt jump layer in the breeding water. However, because reared larvae and reared larvae inhabit and grow by selecting the appropriate salt concentration water areas themselves, physiological disorders due to energy consumption and stress due to osmotic pressure adjustment of larvae and larvae are alleviated and physiological functions Since the disease is activated and the anti-disease property is improved, it is difficult to be violated by the disease, and it is possible to suppress initial depletion that is likely to occur immediately after hatching, which is the weakest period of larvae and larvae. Therefore, according to the management method of the artificial seedling according to the present invention, the survival rate and growth of larvae and larvae can be greatly improved as compared with the conventional management method. For example, in the case of sweetfish, the survival rate until it grows to 0.5 g fry is about 40% in the conventional national average, but it can be improved to 70% or more by using the management method of the present invention. .

  Further, according to the method for managing artificial seedlings according to the present invention, when a fertilized egg is hatched, a fertilized egg floats in a salt concentration layer of the same specific gravity by forming a salt concentration layer in the breeding water, and floats on the water surface. The fertilized egg can avoid the effects of external stimuli such as ultraviolet rays and outside temperature, and the hatching rate and survival rate are increased and the malformation rate is kept low compared to conventional management methods. be able to. For example, in the case of black sea bream, the hatching rate is about 40 to 70% in the national average, and the survival rate after hatching is about 20 to 40%. As a result, the hatching rate was improved to about 80 to 95% and the survival rate was improved to about 70% (2005 breeding results). In addition, the average rate of malformation of sweetfish is several percent to 30%, but by adopting the method of the present invention, the occurrence of malformation could be suppressed to almost zero (2005 breeding results).

  Thus, according to the management method of the artificial seedling according to the present invention, the productivity of various seedlings in the production of the artificial seedling can be stably and improved, and as a result, the profit of the producer can be greatly improved.

  Furthermore, according to the present invention, the anti-disease property of fertilized eggs, larvae and larvae to be reared and managed can be improved without using chemicals, and the disease and abnormality can be prevented. It is possible to suppress reputations such as “Yes,” and “Chemicals are used in ginger,” and gain public understanding of the quality of artificial seedling production.

  In the management of artificial seedlings, the present invention is a method for forming a salinity layer in the breeding water in the aquarium and performing fertilized egg management, larval fish management or larvae management in the breeding water in which the salt concentration layer is formed Can be said.

  In the management method of the present invention, the capacity of the aquarium to be used is not particularly limited, and in the same manner as normal seedling production, fertilized eggs can be managed from beakers with a capacity of 50 L to large ones exceeding 10 t, and larvae and larvae. For management, water tanks of various sizes can be used, ranging from those with a beaker to those with a large capacity exceeding 60 to 80 tons.

  In the management method of the present invention, fertilized egg hatching methods and larvae and larvae breeding methods include fish and crustaceans that inhabit coastal areas, grow from rivers to the sea, grow into adult fish and become mother rivers Applicable to descending migratory fish that return to

  That is, the management method of the artificial seedling according to the present invention can be applied to any kind of coastal inhabiting marine fish, crustaceans, and descending migratory fish. Specifically, flounder, black sea bream, okoze, mahata, etc. as coastal inhabiting marine fish, ayu, salmon, trout, salamander (salmonaceae), shiroo (salidae), etc. And prawns. The management method of the present invention is not limited to the fish and crustaceans listed here.

  In the method for managing artificial seedlings according to the present invention, in the method for raising larvae or larvae, the larvae or larvae may continue to be cultivated as they are until they are released in the breeding water in which the salt excitement layer is formed. There may be no problem, or it may be transferred to breeding water with a constant salinity after it has grown to some extent. In addition, in the fertilized egg management method, it may be hatched in the breeding water in which a salt excitement layer is formed, and after hatching in seawater or fresh water, a salt excitement layer is formed in the aquarium or a hatched larvae is used. What is necessary is just to transfer to the water tank in which the salt leaping layer is formed.

  In the present invention, the water temperature in the water tank may be the same as that for the seedling production. In general, the optimal water temperature for raising larvae and larvae is 10-25 ° C for flounder, black sea bream, and okoze, 5-15 ° C for salmon, 10-20 ° C for sweetfish, 21-27 ° C for troughfish, 20 for prawns. It is known that the fertilized eggs are hatched at the same water temperature as described above. Also in the management method of the present invention, it is preferable to adjust and manage the water temperature using these as a guide.

  Next, an example of an appropriate production method of “bred water having a salt content layer” used in the present invention will be described. There are two main ways to make it. Put seawater in the aquarium and add fresh water (fresh water) or salt water with a lower salt concentration than seawater, or add fresh water (fresh water) or seawater to the aquarium. Alternatively, salt water with a low salinity concentration may be added and either of the methods of injecting seawater from the bottom of the aquarium through a pipe may be employed. In both methods, a salt leaping layer is formed in the boundary area between seawater and freshwater or seawater and saltwater. In addition, when forming a salinity stratum using seawater as a lower layer, it is preferable to inject salt water having a concentration of several percent to 50% lower than the salinity concentration of seawater. However, the blending amount of seawater and fresh water or seawater and salt water, and the salinity concentration of the upper layer and lower layer may be determined according to the type, properties and growth stage of fertilized eggs, reared larvae and reared larvae, and are not particularly limited. As a matter of course, seawater and fresh water or seawater and salt water in the aquarium should not be stirred.

  In the present invention, when a salt concentration layer is formed in the breeding water for breeding larvae and fish of coastal inhabited marine fish, when seawater (30 to 34 ppt) is used for the lower layer, the salinity concentration of the upper layer is In the case of Okoze, 18-25 ppt is appropriate, and in the case of Mahata, 20-25 ppt is appropriate.

  In the present invention, when forming a salt-climbing layer in breeding water intended for breeding migratory migratory larvae, seawater (30-34 ppt) or saltwater slightly thinner than seawater is used for the lower layer, and fresh water is used for the upper layer. Just inject.

  In the present invention, the number of breeding layers of breeding water to be used is not limited to two layers, and breeding water in which three or more salt jump layers are formed may be used. In the case where the salinity layer is made up of three layers, seawater is first put in the water tank, then saltwater having a lower salinity concentration than seawater is injected, and fresh water or thinner saltwater is injected thereon.

  Next, a suitable method for raising fertilized eggs using the breeding water and raising larvae or larvae will be exemplified. First, for coastal inhabited marine fish that hatch with seawater, fertilized eggs can be housed in an aquarium with a salinity layer and hatched as usual. In this case, since the fertilized egg floats in salt water having the same specific gravity as that of itself, the breeding water is preferably adjusted to a salt concentration such that the fertilized egg is concentrated in the stratosphere. That is, fertilized eggs of coastal inhabited marine fish are housed in a tank filled with breeding water that has formed such a salinity layer. Then, even if the fertilized egg is a floating egg, most of the eggs gather and float in the salt concentration layer (within the same specific gravity area), so they can be allowed to hatch as they are. In addition, after hatching in breeding water having a constant salinity, hatched larvae and hatched larvae may be transferred to breeding water in which a salinity layer is formed. Also, in the case of fertilized eggs of descending migratory fish, breeding water that has formed a salinity layer easily by hatching as usual in a tank filled with fresh water and injecting seawater from the bottom into the tank immediately after hatching Can be kept in the aquarium in that state.

  If you keep breeding for a while in the breeding water that formed the salt breakthrough layer, the larvae and larvae that were initially concentrated in the salt breakthrough layer will vary depending on the type, nature, and growth stage in the aquarium. Choose the appropriate salinity yourself and move naturally to the water of that concentration. For example, ayu larvae are concentrated in a low concentration range of about 10 ppt immediately after hatching, but gradually move to a region with a higher salt concentration than the initial stage as they grow. In the flounder larvae, it floats in a thin salinity layer of about 20ppt at the beginning. However, as the transformation stage progresses toward the bottoming stage, it moves to a salty layer and is the first in the seawater layer. It leads to metamorphosis. Thus, in the management method of the present invention, the larvae and larvae naturally move to the water area of the salinity concentration suitable for themselves in the aquarium, so there is no need to adjust the salinity concentration of the aquarium.

  In addition, larvae and larvae have been confirmed to move to lower salinity during the breeding process. There is a high possibility that the parasite that has moved to the lower salinity concentration and dropped the adhering parasite due to the difference in osmotic pressure, or healed and recovered the disease himself. In general, as fish grows, they tend to move to water areas with a high salinity. When the larvae and larvae being reared and managed move to the seawater layer in the tank, the supply of freshwater or diluted seawater is stopped, the amount of seawater supplied is increased, and seawater is filled in the breeding tank.

  The present invention is also applicable to the rearing of shellfish larvae mainly composed of bivalves such as abalone, clam, turban shell, scallop, clam, swordfish and oyster.

  Hereinafter, the present invention will be described in more detail with reference to examples.

<Example of rearing black larvae>
Two indoor aquariums with a capacity of 60 t (capacity 30 t: water depth 80 cm) are prepared, one with 20 t of seawater (salt concentration 32 ppt) is used as the lower layer, and 10 t of salt water with a salinity of 15 ppt is injected from above. The upper layer was filled with breeding water in which a salt leaping layer was formed in the aquarium (this aquarium is referred to as “leaping zone”). The other one accommodated 30 t of seawater (salt concentration 32 ppt) (this tank is referred to as “seawater zone”).

  Both tanks were finely ventilated, and 300,000 black-tailed larvae on the 10th day after hatching were accommodated in each tank, and the breeding was started. As for the total length of black larvae at this time, the average value of those accommodated in the climax zone was 4.53 mm, and the average value of those contained in the seawater zone was 4.45 mm. In both tanks, the water temperature was maintained at 15 to 20 ° C., and rotifer and artemia were fed.

  Most of the croaker larvae housed in the leaping zone gathered in a row in the salt leaping zone formed in the aquarium and continued swimming. On the other hand, the black larva larvae housed in the seawater were diffused throughout the aquarium.

  On the 15th day after hatching, 60 fish were collected indiscriminately from both tanks, and the total length was measured. The average value of the larvae housed in the climbing zone was 6.89 mm, and the average value of the larvae housed in the seawater zone was 5.64 mm. In addition, on the 20th day after hatching, 60 fish were collected indiscriminately from both tanks, and the total length was measured. The average value of black larvae larvae housed in the leaping zone is 8.50 mm and the survival rate is 87.7% (compared to immediately after hatching), and the overall average length of black larvae larvae contained in the seawater zone is 7.94 mm and the survival rate is It was 67.3% (same as above). A graph comparing the full length of black larvae in both tanks is shown in FIG.

  By the 25th day after hatching, the larval larvae gradually moved from the low salinity area at the top of the stratified area to the lower salinity, and by this time most of the larvae were under the aquarium (water Therefore, on the 30th day after hatching, the water supply for seawater was increased, the breeding water was transferred to seawater and switched to seawater breeding.

<Examples of rearing Ayu larvae>
Two indoor water tanks with a capacity of 60 t (water depth: 160 cm) were each filled with 60 t of fresh water, and fertilized eggs of Ayu, which had been egg-managed until just before hatching, were accommodated with a standard of 200,000 eggs per unit and hatched. After hatching, seawater (salinity concentration 32ppt) was supplied from one bottom surface to one, and fresh water was supplied from the top surface to form a salt leaping layer (this water tank is referred to as a “cracking zone”). In the other one, seawater was immediately supplied into a tank containing only seawater (this tank is referred to as “seawater zone”).

  Breeding was started in both water tanks, with 200,000 Ayu larvae on the 10th day after hatching. In both tanks, the water temperature was maintained at 16 to 20 ° C., and rotifer was fed as the feed. The total length of the larvae larvae on the 10th day after hatching was 11.6 mm for those stored in the climax area, and 11.4 mm for those stored in the sea area.

  Most of the Ayu larvae bred in the leaping zone gathered in almost one row in the upper 10 to 20 ppt region of the leaping region and continued swimming. On the other hand, ayu larvae housed in the seawater area were in a state of swimming near the water surface.

  On the 30th day after hatching, 60 fish were collected indiscriminately from both tanks, and the total length was measured. The average value of the ayu larvae housed in the climax was 21.5 mm, and the average value of the ayu larvae housed in the seawater area was 21.0 mm. In addition, on the 50th day after hatching, 60 fish were collected indiscriminately from both tanks, and the total length was measured. The average value of the Ayu larvae housed in the climatic zone is 31.7 mm and the survival rate is 84.3% (compared to that immediately after hatching). The average value of the Ayu larvae contained in the seawater zone is 29.7 mm and the survival rate is 66. 8% (same as above). A graph comparing the total length of sweetfish larvae in both tanks is shown in FIG.

  During this period, most of the larvae in the leaping zone moved to the lower layer (seawater layer) of the aquarium, so the water supply was switched to seawater and all larvae were moved to seawater breeding.

<Examples of breeding Oniokose and Mahata>
Four test black tanks with a volume of 1 kL (70 cm in depth), 2 brackish waters (salt content of 22 ppt), seawater (salt content of 34 ppt) injected from the water surface, and a salt concentration layer formed in the breeding water, Seawater was injected from the surface of the water to create two control tanks. Fertilized eggs of Mahata (10,000 grains) and Oniochoze (12,000 grains) were accommodated in the control water tank, respectively, and half of the fertilized eggs of the control water tank were accommodated in the test water tank. Mahata was raised until the 21st day after hatching, Oniokose was raised until the fry (23rd day), and the distribution status, feeding status, growth / survival status of the larvae were examined. .

  Two species of larvae in the control tank were dispersed throughout the water column. Mahata larvae in the test tank are concentrated in the upper layer (salt content 22.0 to 24.8ppt) of water depth 0-20cm throughout the test period, the initial feeding is also active, and the survival rate at opening is 96% there were. This is 1.4 times the mahata larvae in the control aquarium. Oniokoze larvae in the test tank are distributed in the upper layer (22.0-23.5ppt of salinity) in the first day, and the distribution range is expanded in the middle layer (24.1-33.4ppt) after the second day. did. The survival rate of Oniokose on the last day of breeding was 82%. This is more than 10% higher than the survival rate (68.2 ± 6.0%) of the Oniokose larvae in the control aquarium.

《Examples of rearing of crabs》
Four circular polycarbonate tanks with a capacity of 2kL (water depth of 100cm) were prepared, and a water tank (in this tank, which was formed with a salt-climbing layer by pouring brackish water (salt concentration 20ppt) from the water surface and seawater (32ppt) from the bottom surface. 2) and 2 tanks infused with seawater (this tank is called "seawater tank"), each of which accommodates 20,000 larvae of squirrel crabs and distributes the larvae. The situation was observed.

  The zoea larvae gathered in the salinity layer in the salinity layer, where the salinity layer was 25-30 ppt, but diffused throughout the seawater tank. In the climax formation tank, swimming was also active, and there was no damage of aquatic bacteria (fungi) occurring in the zoea period, and the survival rate was 17.1%. On the other hand, in the seawater tank, the survival rate became 0% due to depletion due to damage by aquatic bacteria.

  When the zoea larvae grew in the climax formation tank and the megalopa period began, fresh water was fed from the surface of the water to form a salt cradle layer with fresh water as the upper layer, and the breeding was continued. Movement from the individual to the freshwater area in the aquarium was observed. The survival rate at this time was 38.1%. The survival rate when fresh water was not supplied was 8.3%.

  As described above in detail, in the method for managing artificial seedlings according to the present invention, when raising larvae and larvae, the hatching rate of larvae and larvae is obtained by a simple method of using breeding water in which a salt excitement layer is formed. It is possible to improve the survival rate and growth rate, improve and stabilize the productivity of seedlings in artificial seedling production, and as a result, greatly improve and stabilize the profits of producers.

  In the artificial seedling management method according to the present invention, when a fertilized egg is hatched, the hatching rate or survival rate of the fertilized egg is increased by a simple method of using breeding water in which a salt concentration layer is formed. The rate can be reduced, and the productivity of seedlings in artificial seedling production can be improved and stabilized. As a result, the profits of producers can be greatly improved and stabilized.

It is the graph which showed the growth property (full length size) of the black sea in contrast with the method of this invention, and the conventional method. It is the graph which showed the growth property (full length size) of sweetfish in contrast with the method of this invention and the conventional method.

Claims (6)

  In artificial seedling production, when breeding marine fish, migratory fish larvae or crustacean larvae, larvae and larvae are formed while forming a salt excitement layer in the aquarium water and selecting their own appropriate salt concentration in the aquarium Or the management method of artificial seedlings characterized by raising larvae.   In artificial seedling production, when fertilized eggs are hatched, a salinity layer is formed in the breeding water in the aquarium, and the fertilized eggs are floated and hatched in the aquarium in a salt concentration range that matches their specific gravity. Management method for artificial seedlings.   The management method according to claim 1, wherein seawater is used as a lower layer, and a salt concentration layer is formed with salt water or fresh water having a concentration according to the type, characteristics and growth stage of larvae or larvae as an upper layer, and the breeding water is used. A method for managing artificial seedlings for raising larvae and larvae.   3. The management method according to claim 2, wherein sea salt is used as a lower layer, a salt concentration layer is formed with salt water or fresh water as a top layer according to the type, properties and growth stage of a fertilized egg, and fertilized using the breeding water. An artificial seedling management method that hatches eggs.   4. The management method according to claim 3, wherein larvae of marine fish such as black sea bream, flounder and okoze or crustacean larvae such as black crab, tiger prawn and crab are raised using breeding water having a lower concentration of salt water than seawater. Management method of artificial seedlings to be bred.   The management method according to claim 3, wherein breeding juvenile fish such as sweetfish, salmon, trout, etc. are bred using breeding water with fresh water as an upper layer.