JPH0226938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for raising prawns in the incubation stage during the cultivation process of prawns.

[Background technology] Onitenaga shrimp is a freshwater shrimp that is native to Southeast Asia and lives in rivers.The shell is red with a bluish tinge.It is also commonly called Matsuba shrimp because it has long, thin claws that are almost twice the length of its body. In recent years, it has been attracting attention as an edible shrimp that can replace kuruma shrimp and flax shrimp. Traditionally, such shrimps were imported and raised as pets for viewing, but
This is a very simple process that involves importing shrimp that are already in the form of shrimp and raising them in an aquarium with food, and it has been thought that the eggs can only hatch under natural conditions. However, the present inventor discovered that although giant shrimp are originally freshwater, they live near river mouths during the spawning season, and therefore require water containing a certain amount of salt at least during the period before and after the eggs hatch. We focused on seawater so that the conditions would be the same as in natural estuaries, at least for the period from the time when female prawns incubate their eggs until the eggs hatch, pass through floating stage larvae (zoea), and become young shrimp. By raising the shrimp in diluted seawater diluted with fresh water, it has become possible to artificially hatch the eggs of the shrimp, which had previously been considered impossible. However, seawater is always required to hatch the eggs of the prawns, and the cost of transporting seawater and the cost of farming prawns in areas where seawater is difficult to obtain.
There was a problem that storage management costs were high and inconvenient.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and its purpose is to raise O. prawns during the incubation period in as little seawater as possible, The object of the present invention is to provide a method for raising giant lobsters during the incubation period, which enables the farming of giant lobsters even in difficult areas.

[Disclosure of the Invention] The method of the present invention involves rearing giant shrimp at a ratio of one male to multiple females in freshwater at a water temperature of 23°C to 32°C, and removing the females that have incubated eggs from seawater. It is characterized by being reared in diluted seawater with a seawater content of 20% to 40% and a water temperature of 23°C to 32°C. As mentioned above, prawns require seawater from the time they incubate their eggs until they hatch, become floating larvae, and turn into young shrimp, but until the female incubates the eggs. It is okay to keep them in fresh water.
Originally, Onitenaga shrimp lived in fresh water.
Since they feed and grow in freshwater areas and move to the river mouth only during the spawning season, it is better to keep them in freshwater until they incubate the eggs, which will create an environment that is closer to the natural ecology of Onitenaga shrimp. It is something that can be done. The reason for rearing multiple females per male in freshwater is to increase the efficiency of egg incubation. The ratio of females to one male is preferably 5 to 8; if the ratio is higher than this, fights will occur between the females, and if it is lower, the efficiency of egg incubation will be reduced.
The appropriate freshwater temperature during the incubation period is 28°C. Females that have incubated eggs will drop their eggs if left in fresh water, so after incubating eggs, they are raised in diluted seawater diluted with fresh water to create an environment similar to a natural estuary. . According to experiments, the concentration of diluted seawater suitable for hatching eggs is between 20% and 40%.
The most favorable results were obtained when the seawater content was 30%. According to experiments conducted by the present inventor, it has been found that seawater is always necessary for eggs to hatch. It was also found that although seawater is necessary, in pure seawater, that is, 100% seawater, even if the eggs hatch, they die during the floating stage before they become young shrimp. Furthermore, the temperature of the diluted seawater is preferably 28°C.
In the present invention, the female eggs are raised in diluted seawater after incubation, so it is possible to artificially incubate the eggs of the incubated female, and moreover, it is possible to artificially incubate the eggs of the female. Since we reared males and females in freshwater, they can be easily reared using well water or tap water, and they do not require a large amount of seawater. This makes it possible to easily cultivate giant shrimp even in difficult areas.

Hereinafter, the method of the present invention will be explained in more detail with reference to Examples. FIGS. 1 to 5 are diagrams showing a schematic configuration of a culture apparatus using the breeding method of the present invention. The one shown in Figure 1 is a freshwater aquarium, and in tank 1, which is about 1 tsubo in size, a harem is created by releasing parent giant shrimp in a ratio of 1 male to 5 to 8 females. , prepare for mating. The number of males does not necessarily have to be one, and when a plurality of males are included, the number of females may be increased according to the above ratio. The water in this aquarium 1 is pumped up by a pump, filtered through a filter, and then returned to the aquarium 1. Also, air is constantly supplied to the water in the aquarium 1 to control the water in the water. Prevents the amount of oxygen from decreasing. The temperature of the water in the water tank 1 is maintained within the range of 28°C to 30°C by a heater equipped with a temperature control device. If they are raised in this state while being fed, mating will occur and eggs will be laid between 6 and 20 hours after mating. The female seaweed protects the eggs during the incubation period until they hatch and the larvae swim out. If a female with eggs is left in fresh water, she will drop the eggs, so she is taken out of a freshwater tank 1 and released into a diluted seawater tank 2 as shown in FIG. At this time, in order to easily pull out the female with eggs from the tank 1, it is better that the tank 1 is not too wide, and as mentioned above, it is most preferable to use a tank 1 with an area of about 1 tsubo. be.
The diluted seawater in tank 2 has a seawater content of 30% by volume.
It is becoming. Natural seawater is used as seawater. The inventors have also attempted hatching experiments using saline water or artificial seawater, but although the eggs hatch in water other than natural seawater, they die at the larval stage and grow to the shape of seawater. turned out to be difficult. The water temperature in tank 2 is also maintained within the range of 28°C to 30°C, and air injection and water circulation and filtration by a pump are performed in the same manner as in tank 1. The aquarium 2 for diluted seawater is partitioned with a wire mesh 3, and the females with incubating eggs are kept isolated one by one. The reason why females with eggs are isolated in this way is that if females with eggs are kept close together in a small space, there is a risk that they may fight and drop the eggs.
According to the inventor's experiments, when a glass aquarium 2 with a size of about 60 cm x 30 cm and a water depth of about 30 cm was divided into four equal parts with a wire mesh 3 with three releases, most eggs were dropped. Nothing happened. The number of days it takes for the eggs to hatch after incubation varies depending on the water temperature; the higher the water temperature, the fewer days it takes for the eggs to hatch. According to the experiment, the water temperature was 23℃,
For each case of 24℃, 26℃, 28℃, 30℃, and 32℃, the number of days required for hatching is 25 days, 23 days, 20 days, 17 days, 16 days, and 15 days after incubation, respectively. Ta. It is best to keep the water temperature as constant as possible from the time the female incubates until the eggs hatch, but if the temperature changes unavoidably, the water temperature should be kept at 28℃.
It is preferable to set it within the range of ~30°C. Increasing the water temperature to 32°C will further shorten the number of days required for hatching, but this is not desirable because the energy cost required to maintain the water temperature is high. Raising the water temperature further than 32°C is also undesirable, as the water tends to become cloudy, and even if the eggs hatch, they are more likely to die at the larval stage. Water temperature 28℃
In this case, the number of days from incubation until the eggs hatch is 17 days, so the female that has incubated the eggs two or three days before that time is further transferred to another aquarium 4 as shown in Figure 3. . In this aquarium 4, females that have incubated eggs and are about to hatch are kept in a breeding net 5 made of wire mesh. The water temperature and seawater content in tank 4 are the same as in tank 2, and the point that air is injected to prevent the oxygen in the water from decreasing is the same as in tank 2, but the water is circulated by a pump. No filtration. This is because when the eggs hatch, the larvae swim out, so if water is circulated and filtered using a pump, the larvae will be caught in the filter and die. When the water in the tank 4 becomes dirty, 20% to 30% of the water is replaced. Aquarium 4 is a round aquarium made of polyethylene or concrete with a capacity of 500 to 1000 liters.The reason for using a round aquarium is that compared to a square aquarium, there are no corners, so the water can stagnate. This is because it is difficult to clean and the water does not easily spoil. Since the larvae hatched from the eggs are much smaller than the mesh of the breeding net 5, they can freely move inside and outside the breeding net 5 and spread throughout the aquarium 4. In this state, the female shrimp is pulled up from the aquarium 4 along with the breeding net 5 and returned to the freshwater aquarium 1. After this,
For about 40 days, as shown in Figure 4, a bubbling device 6 etc. is inserted into the aquarium 4, air is injected and heat is kept using a heater, and the larvae are reared and managed until they become young shrimp. be. The water temperature and seawater content are the same as in FIG. In the early stage, within 10 days after hatching, the larvae themselves are small plankton, so it is necessary to feed them plankton even smaller than the larvae. In the inventor's experiments, it was found that it is preferable to hatch brine shrimp (Artemia: a type of shrimp) eggs and provide them with fresh plankton. Brine shrimp eggs are commercially available from, for example, "Nippon Animal Pharmaceutical Co., Ltd.".
This brine shrimp is very easy to hatch, and the time required for hatching is said to be 24 to 48 hours when the water temperature is about 28° C. in 3% saline or pure seawater. Brine shrimp must be fed to larvae only after hatching. If you feed plankton that has been left for a long time after hatching, the plankton will grow in size during that time, and the larval shrimp will be eaten. From about 10 days after hatching, feed minced clams and shrimp. The larvae before forming into young shrimp are swimming relatively above the tank 4. If you continue to raise them, some larvae will take the form of young shrimp in about 28 days after hatching, and about half (strongly) will take the form of young shrimp about 30 to 35 days after hatching. It turns and descends to the bottom of tank 4. And after hatching, about
After 40 days, almost all of the shrimp will be in the form of young shrimp. Once they have grown to this state, they will not die even if kept in fresh water, so they can be stocked in a large aquarium 7 or pond as shown in FIG. 5 and kept in fresh water. Breeding in this state is very easy.
The eating habits of the giant shrimp are omnivorous, and in the wild they eat anything, including aquatic worms, aquatic insects, small shellfish, crustaceans, fish and animal meat, grains, algae, and the soft leaves and stems of aquatic plants. . When cultivating in the aquarium 7, etc., feed mixed feed such as trout, carp, sweetfish, sardines, egg shells, etc. Regarding water temperature, since shrimp are originally from the tropics or subtropics, they are strong against high water temperatures but weak against low water temperatures.The water temperature at which they can normally live in is within the range of 18°C to 35°C, and the preferred water temperature is 25°C. to 32℃. The water temperature
If the temperature drops below 20 degrees Celsius, they will stop eating, and if the temperature drops below 14 degrees Celsius, they will die. Four to five months after hatching, Onitenaga shrimp develop into parent shrimp and lay eggs. The number of eggs laid by a single parent varies depending on the size, but on average it is around 20,000 to 30,000 eggs, and if the water temperature and other living conditions are good, they will spawn 5 to 7 times a year. After hatching, they grow to a length of 11 to 15 centimeters in about six months, and 30 to 40 centimeters in two years, but the size is 15 to 15 centimeters for the domestic market.
It seems appropriate to take the fish out of the aquarium 7 and ship it when it is about centimeters in size.

[Effects of the Invention] As described above, the present invention raises shrimps in fresh water at a water temperature of 23°C to 32°C at a ratio of one male to multiple females, and among them, the females that have incubated eggs are Seawater was diluted with fresh water to give a seawater content of 20% to 40%, and the water temperature was kept at 23°C to 32°C.The eggs were then hatched after the natural shrimp incubated. Until then, it is possible to artificially create a situation that closely matches the ecology of living near the river mouth, and this has made it possible to artificially hatch eggs of the shrimp, which was previously considered impossible. Since the female is kept in freshwater with the male until it incubates, it can be easily reared using well water, such as tap water, and does not require a large amount of seawater. The advantage of this method is that it is easy to farm giant shrimp even in areas where it is difficult to obtain shrimp.

[Brief explanation of drawings]

The drawings show an aquaculture device using the method of the present invention, and Fig. 1 is a schematic diagram of the aquarium used for mating and spawning of prawns, and Fig. 2 is a tank used for the period from incubation to just before hatching of prawns. Figure 3 is a perspective view of an aquarium used for hatching prawn eggs, Figure 4 is a perspective view of an aquarium used for rearing larvae after hatching, and Figure 5 is an aquarium used for rearing young shrimp. FIG. 1, 2, 4, and 7 are water tanks, 3 is a wire mesh, 5 is a breeding net, and 6 is a bubbling device.

Claims (1)

[Claims] 1. Breeding giant shrimp in fresh water with a water temperature of 23°C to 32°C at a ratio of one male to multiple females,
Among these, the females with eggs were diluted with fresh water to give a seawater content of 20% to 40%, and the water temperature was adjusted to 23°C to 32°C.
A method for raising prawns during the incubation period, which is characterized by raising them in diluted seawater at a temperature of ℃. 2. The method for raising prawns during the incubation period as set forth in claim 1, which comprises raising prawns at a ratio of 5 to 8 females to 1 male in fresh water. 3. The method for raising prawns during the incubation period according to claim 1, wherein the seawater is natural seawater and the seawater content is 30%. 4. The method for rearing giant shrimp during the incubation period according to claim 1, wherein the temperature of the fresh water and diluted seawater is within the range of 28°C to 30°C.