JP2840872B2 - Gastropod aquaculture method - Google Patents

Description

The present invention relates to a method for cultivating gastropods such as abalones, and more particularly to a method for cultivating gastropods such as abalones in which the growth rate of gastropods is increased by adjusting the light environment.

[Conventional technology]

Recently, the amount of gastropods such as abalone that can be collected in the natural world has decreased, and therefore, measures have been required for the growth of gastropods. As one of them, for example, abalone is cultivated to a size of about 15 mm, and the obtained abalone seedlings are released into the natural world to secure abalone resources. Further, as another method, a method of culturing gastropods such as abalone from seeds and seedlings to a size that can be used for food has been attempted.

[Problems to be solved by the invention]

However, the growth rate of abalone is slow, and it takes about one year or more to produce seeds of about 15 mm, which increases the production cost. Furthermore, even if the seedlings are released into the natural world, it takes several years or more to obtain a size of about 90 mm that can be used for food, and at present the recovery rate is not very good. On the other hand, when a gastropod such as abalone is cultivated until it becomes edible, it is currently unprofitable because the cultivation period is long.

On the other hand, various attempts have been made to increase the growth rate of abalone. For example, a method of examining differences in abalone genetic traits and selecting and growing those having good growth (Japanese Patent Application Laid-Open No. 62-259526), sterilizing abalone egg and sperm fertilization and larval development, or Abalone cultivation method carried out under conditions where only beneficial bacteria can live (Japanese Patent Laid-Open No. 62-32829)
), And a method of culturing abalone in seawater containing no impurities under conditions of supplying sufficient dissolved oxygen to a size that can be used for food (Japanese Patent Laid-Open No. 61-199736).

However, even with such a method, there was a problem that the growth of abalone seedlings could not be sufficiently promoted, and it was not profitable eventually.

[Problems to be solved by the invention]

An object of the present invention is to provide a method of cultivating a gastropod such as abalone at a high growth rate by stimulating a feeding behavior.

[Means for solving the problem]

The gastropod cultivation method according to the present invention contains the gastropod seedlings and the like in a breeding container installed in an aquarium or the sea, using a light source that creates a bright light environment and a light-shielding unit that creates a dark light environment. The surroundings are changed from a bright light environment to a dark light environment at least once a day.

Here, the light shielding means for creating the dark light environment includes, for example,
Means for blocking light from the light source or for turning off or dimming the light source.

[Action]

The breeding capacity and its surroundings in the present invention are alternately set to a bright and dark light environment by turning on and off the light source and shading by the light blocking means. Such a light environment is switched from light to dark at least once a day. By setting the number of times to exceed, the number of times of feeding of gastropods is increased, so that the growth time can be shortened.

(Example of the invention)

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First
The figure shows a culture system for carrying out the method of the invention. In the figure, reference numeral 1 denotes a water tank which constantly supplies a constant amount of seawater. Numeral 2 is a breeding car, for example, having two breeding capacities installed in the seawater of the aquarium 1. The breeding car 2 accommodates an abalone 3 such as a black abalone or an azo abalone. Reference numeral 4 denotes a rectifying plate installed in the water tank 1, which rectifies seawater sent from the aeration tank 5 through the pipe 6, and
Send out within. 7 is a table on which the aeration tank 5 is installed, 8 is a water tank 1
, A water bath that receives seawater flowing out from here
9 is a light shielding means for covering the breeding car 2 and its surroundings, for example, a black vinyl sheet, and 10 is a light source for illuminating the breeding car 2 and its surroundings, for example, a fluorescent lamp of about 20 watts. In addition to a halogen lamp such as a sodium lamp, sunlight can be used. In addition,
The black vinyl sheet 9 and the fluorescent lamp as the light source 10 are attached to a wooden frame 11 installed on the water tank 1 or the like.

In such an aquaculture system, a certain number of seeds of the abalone 3 are accommodated in a rearing cage 2 immersed in seawater in a water tank 1, and the fluorescent lamp 10 is turned on and off or turned off using a timer. When the light source is a solar light source, two light environments can be created by covering or removing the black vinyl sheet 9. That is, in the present invention, the operation of rearing the abalone 3 in a bright light environment for a certain period of time (12 hours or less), and then reducing the light of the rearing environment to a certain brightness or less for a certain period of time (12 hours or less) is repeated. . In this case, the degree of brightness is
In principle, the degree to which nocturnal abalone 3 stops its activity and the darkness when starting its activity are defined.

Further, the change from the light period, that is, the bright light environment, to the dark period, that is, the dark light environment, may be performed more than once per day. Under natural conditions, the transition from light to dark is usually one time at sunset. In contrast, in the method of the present invention, the total time of one light period and one dark period is set to less than 24 hours, and the times of the light period and the dark period need not be the same, but may be different. Is also good. For example, when the light period and the dark period are each 6 hours, the change from the light period to the dark period is twice per day. Further, the minimum time of the light period and the dark period is estimated to be such a time that gastropod organisms such as abalone can recognize the light period or the dark period,
It takes about 2 hours. Here, other breeding conditions,
For example, there is no particular limitation on the water temperature, breeding density or flow rate.

As described above, when the abalone 3 changes from the light period to the dark period, that is, in the natural world, it performs feeding behavior near the sunset time, so the number of changes from the light period to the dark period is larger than that in the natural world. By increasing, the chance of stimulating the abalone 3 feeding behavior increases. As a result, the growth of the abalone seeds and seedlings is accelerated and promoted, and the cultivation period can be shortened. Therefore, the production amount of the abalone 3 is increased, the price of the edible abalone product can be reduced, and the stable production of the abalone 3 is not affected by natural conditions.

In the above-described embodiment, the breeding of the abalone 3 in the aquarium 1 has been described. Further, two or more light sources may be used in combination, and the same effect as in the above embodiment can be obtained.

Next, the following experiment was conducted on the culture of the abalone seedlings, and it was confirmed that when the time cycle between the light period and the dark period was shortened, the growth amount increased.

[Experimental method] The experimental plots were divided into I-IV plots with different light periods, and in consideration of accidents such as death on the way, two plots (pairs) were set for each plot under substantially the same conditions in each plot, and It accommodates 50 healthy and almost standard black abalone seedlings (400 total). The light cycle of each section was set by a timer as follows.

Section I has a 12-hour light-dark cycle with a 12-hour light and dark period, and II
The section has a cycle of 18 hours light and 6 hours dark, the section III has a cycle of 6 hours light and 18 hours dark, and the section IV has a cycle of switching between light and dark every 6 hours.

During the experiment, the water temperature was not adjusted, and the amount of injected water (pumped seawater) was adjusted to about 500 ml / min by adjusting the injection cock (water exchange rate was approximately 1 revolution / day). Lighting is wooden frame 11 on top of aquarium 1
And a 20W fluorescent lamp (1
(Light type, daylight color), and a total of eight lights were attached to one light, and the surroundings were covered with a black vinyl sheet 9 so as not to receive light from the outside (the water surface illuminance at the center of the breeding basket was about 4000 lux). Ventilation is performed by raising an airstone of 5cm in diameter to the breeding basket 2.
Continuous aeration was performed by throwing in each piece. The feed was raw squid and a sufficient amount was administered almost regularly (approximately once every 4 to 7 days).
40-50g). In addition, at the time of feeding, the amount of feeding and the amount of remaining food collected were measured each time.

[Experimental Results] As shown in Table 1, only two dead individuals were found in the first case C1 in the III section, as shown in Table 1.
The feeding amount during the experiment was not observed in the other plots, and the amount of feeding was 170 g per each case. Among them, the plot with the highest total food consumption was the first in the IV plot as shown in Table 1. In case C1
107.7g was fed. The lowest value was 93.7 g in the second case C2 in the section II, and the total food consumption in the other sections was 96.3 to 1
It was in the range of 01.3 g. As a result, the highest value of the shell growth (growth rate, daily growth amount) was 13.0% in the first case C1 of the IV section, as shown in FIG. 2 (a) and Table 2.
The daily growth amount was 77.8 μm, and the lowest value was 8.1% and 48.1 μm in the second case C2 in the section III. In comparison of the experimental section, relatively high growth was observed in section IV,
There is no clear tendency in plots II and II.
In District I, it was somewhat poor. As shown in FIG. 2 (b) and Table 2, the maximum value (weight increase rate, daily weight gain)
In the first case C1 in the IV ward, the rate of weight gain was 51.2% and the weight gained daily was 13.4
mg, and the lowest value was 24.4% in the first case C1 of the I-section.
%, The daily weight gain was 6.6 mg. IV for comparison of experimental sections
The highest value was obtained in the section, and the values tended to decrease in the order of section III, section II, and section I. The feed conversion efficiency calculated from the feed intake and the weight gain is as shown in FIG. 2 (d) and Table 3.
The highest value was 20.0% in the first case C1 in the IV section, and the lowest value was 10.4% in the first case in the I section. In the comparison of the experimental sections, as in the case of the aforementioned weight gain,
The values tended to decrease in the order of Section II and Section I.

[Effects of the Invention] As described above, according to the present invention, a gastropod seedling or the like is stored in an aquarium or a breeding container installed in the sea, using a light source for creating a bright light environment and a light shielding means for creating a dark light environment. ,
Since the breeding container and its surroundings are changed from a bright light environment to a dark light environment at least once a day, the breeding container and its surroundings are cycled through a light period and a dark period more than those in nature. As a result of the shortening, the number of times of gastropod feeding can be increased, whereby the efficiency of food conversion can be increased and the growth of gastropods can be greatly promoted as compared with the conventional method. Thus, the production efficiency of such gastropods can be improved, and the production cost and the market price can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a culture system for realizing a gastropod culture method according to one embodiment of the present invention, and FIGS. 2 (a) to 2 (d) are characteristic graphs for explaining the results of a culture experiment according to the present invention. Daily growth, daily weight gain, total food consumption and feed conversion efficiency are shown for each experimental group. DESCRIPTION OF SYMBOLS 1 ... aquarium, 2 ... breeding container, 3 ... gastropod, 9 ... shading means, 10 ... light source.

Claims (1)

(57) [Claims] 1. A gastropod seedling or the like is accommodated in a breeding container installed in an aquarium or sea, and a bright light is applied to the inside and surroundings of the breeding container by using a light source for producing a light period and a shading means for producing a dark period. A gastropod cultivation method characterized in that it is produced at least once a day by appropriately selecting an environment and a dark light environment in terms of time.