JP2022006652A - Bivalve aquaculture method and aquaculture apparatus - Google Patents

Abstract

To provide an aquaculture method and an aquaculture apparatus in which natural decrease of physical strength due to spawning of bivalve and stress caused by rise of a seawater temperature are reduced, and thereby the bivalve is prevented from falling dead and stable aquaculture can be performed.SOLUTION: A bivalve aquaculture apparatus 1 includes: a breeding tank 11 where seawater is filled; a first measurement device 21 for measuring a temperature of the seawater in the breeding tank 11; a second measurement device 22 for measuring the body weight and gonad weight of bivalve S, and calculating the gonad development quotient for showing the development degree of germ cells; and a cooler 12 for adjusting a temperature of the seawater. The cooler 12 comprises: sea water temperature adjustment means 121 for lowering the temperature of the seawater below the reference temperature, when the temperatures of the measured seawater exceeds a reference temperature suitable for the aquaculture of the bivalve; and reference temperature adjustment means 122 for lowering the reference temperature, when the temperature of measured seawater is lower than the reference temperature and the calculated gonad development quotient exceeds the reference index.SELECTED DRAWING: Figure 1

Description

The present invention relates to aquaculture methods and aquaculture devices for land-based aquaculture of bivalves such as lajonkairia lajonii, freshwater clams, and clams.

Conventionally, aquaculture methods and aquaculture devices for cultivating shellfish and the like in a healthier and more productive manner by providing a favorable aquaculture environment have been proposed. For example, in Patent Document 1, aquaculture organisms such as shellfish are provided on aquaculture shelves installed so as to have a predetermined height from the bottom surface in aquaculture area where the water level can be adjusted, and the water level in the aquaculture area is adjusted. By controlling the water level between the dry state where the aquaculture organisms on the aquaculture shelf are exposed from the water surface and the underwater state where the aquaculture organisms are submerged in water, the survival of the aquaculture organisms such as shellfish can be obtained. Disclosed are aquaculture methods and aquaculture facilities for aquaculture organisms that provide optimal aquaculture levels, shorten aquaculture periods and reduce aquaculture during high water temperatures.

JP-A-2015-177787A

However, in the cultivation of bivalve molluscs in natural sea areas, there is a problem that a large amount of bivalve molluscs die from May to September when the seawater temperature rises. Even in the conventional methods and facilities, the bivalve mortality occurs due to the depletion of physical strength due to spawning of the bivalve and the excessive stress due to the rise in seawater temperature. Therefore, the present invention provides a aquaculture method and aquaculture apparatus capable of reducing the loss of physical strength due to spawning of bivalve molluscs and stress due to an increase in seawater temperature, suppressing the death of bivalve molluscs, and performing stable aquaculture.

The method for cultivating bivalves of the present invention is a method for cultivating bivalves in a breeding tank filled with seawater, the first measuring step of measuring the temperature of the seawater in the breeding tank by the first measuring device, and the above-mentioned measurement. When the temperature of the seawater exceeds the reference temperature suitable for cultivating the bivalves, the seawater temperature adjustment step of lowering the temperature of the seawater in the breeding tank to the reference temperature or lower by the cooler, and the second measuring device are used to lower the temperature of the bivalves. The second measurement step of measuring the weight of the gonads and the weight of the gonads and calculating the gonad development index indicating the degree of development of the germ cells, and the measured temperature of the seawater being equal to or lower than the reference temperature and the calculated gonad development. When the index exceeds the reference index, the reference temperature adjusting step of lowering the reference temperature is included.

Further, the bivalve culturing device of the present invention measures a breeding tank filled with seawater, a first measuring device for measuring the temperature of the seawater in the breeding tank, and the weight of the bivalve and the weight of the gonad, and the germ cells. It is equipped with a second measuring device for calculating the gonad development index indicating the degree of development of the seawater, and a cooler for adjusting the temperature of the seawater. When the temperature is exceeded, the seawater temperature adjusting means for lowering the temperature of the seawater to the reference temperature or less, the measured seawater temperature is the reference temperature or less, and the calculated gonad development index is the reference index. If it exceeds, the reference temperature adjusting means for lowering the reference temperature is included.

According to the method and apparatus for cultivating these basilica, the seawater temperature of the breeding tank in which the balustrade is cultivated and the gonad development index of the cultivated bachelor are periodically measured, and these seawater temperature and gonad development are measured. Depending on the index, it is possible to always maintain an appropriate seawater temperature and reference temperature.

Further, it is desirable that the gonad development index is obtained by rounding the GSI calculated by dividing the measured gonad weight of the bivalve by the body weight into 6 stages of 0 to 5. From this staged gonad development index, the degree of germ cell development of bivalve molluscs can be easily grasped.
Further, it is desirable that the reference index is the stage 3 indicating that germ cells are developed and male and female can be discriminated. When the measured seawater temperature is below the reference temperature and the germ cell development is observed beyond the extent that male and female can be distinguished, the reference temperature can suppress the germ cell development by lowering the reference temperature. Can be set.

Further, it is desirable that the reference temperature is 5 ° C to 28 ° C. By setting the reference temperature to 5 ° C. to 28 ° C., which is the most suitable temperature for culturing bivalve molluscs obtained in the test, it is possible to prevent the loss of physical strength due to spawning of bivalve molluscs and reduce stress.

(1) According to the bivalve aquaculture method and the aquaculture apparatus of the present invention, it is always possible to maintain an appropriate seawater temperature and reference temperature of the breeding tank according to the measured seawater temperature and gonad development index, which is always good. An aquaculture environment is provided, it is possible to prevent the loss of physical strength due to spawning of bivalves and reduce the stress on the bivalves, suppress the death of bivalves, and perform stable aquaculture.

(2) Further, it is easy to set the germ gland development index in 6 stages of 0 to 5 and lower the reference temperature when the measured seawater temperature is below the reference temperature and the germ gland development index is in stage 3. Since it is possible to grasp the degree of development of germ cells of birch shells and set a reference temperature that can always suppress the development of germ cells, more stable cultivation can be performed.

(3) Further, by setting the reference temperature to 5 ° C to 28 ° C, the bivalve molluscs are cultivated at a more suitable seawater temperature, so that more stable culturing can be performed.

It is a schematic block diagram of the bivalve aquaculture apparatus which concerns on embodiment of this invention. It is a flow chart of the bivalve aquaculture method which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail, but the description of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention is described below unless the gist thereof is changed. It is not limited to the contents of. In addition, when the expression "-" is used in this specification, it is used as an expression including numerical values before and after it.

[Aquaculture equipment]
FIG. 1 is a schematic configuration diagram of an aquaculture apparatus according to an embodiment of the present invention. The culture device 1 is a breeding tank 11, a first measuring device 21 for measuring the temperature of seawater, and a second measuring device for measuring the weight and gonad weight of the bachelor shell and calculating the gonad development index indicating the degree of development of germ cells. 22 is provided with a cooler 12 for adjusting the temperature of seawater, a protein skimmer (not shown) for removing excreta of bivalves, and a seawater filtration device (not shown) for filtering seawater.

The breeding tank 11 is filled with seawater, a sandy substrate T is laid, and a culture cage (not shown) is provided. Then, the bivalve S is released into the breeding tank 11 and cultivated. The seawater may be either natural seawater or artificial seawater. The salinity of seawater is preferably 20 ‰ to 36 ‰. In addition, the temperature of seawater is set to a reference temperature suitable for bivalve aquaculture.

Bivalve S is Lajonkairia lajonii, Shijimi, Clam, Tairagi, Trigger, Mactra chinensis, Milgai, Pacific oyster, Crassostrea nipponica, Shikamegaki, Ostrea oyster, Tairagi, Hiragaki, Hiougi mussel, Azumanishiki, Akoya, Kumasarubou, Pearl oyster, Black pearl oyster, etc. It is a mollusk classified as a bivalve. The substrate T is a sand-like substance in which the bivalve S can easily dive, and the particle size, particle size, and specific gravity may be changed according to the type of the bivalve S to be cultivated.

The reference temperature is the temperature of seawater suitable for culturing bivalve molluscs S, and varies depending on the type of bivalve mollusc. For example, in the case of white pearl oysters, black pearl oysters, pearl oysters, etc. cultivated at relatively high water temperatures such as northern Australia, Okinawa, and Amami Oshima, the reference temperature is preferably 20 ° C to 28 ° C. In the case of scallops cultivated at relatively low water temperatures such as Hokkaido and Tohoku, the reference temperature is preferably 5 ° C to 19 ° C. In addition, in the case of lajonkairia lajonii, ark shell, pen shell, Pacific oyster, crassostrea nipponica, pearl oyster, etc., the reference temperature is preferably 16 ° C to 22 ° C.

Further, the configuration of the aquaculture device 1 differs depending on the type of the bivalve S. For example, in the case of submerged bivalves such as Lajonkairia lajonii, Blood clam, and Pen shell, the culture apparatus 1 includes a substrate T and a culture cage. On the other hand, in the case of adhesive bivalves such as Pacific oysters, crassostrea nipponica, and pearl oysters, the culture apparatus 1 includes a culture cage and does not require a substrate T.

The first measuring device 21 is, for example, a data logger for temperature recording. The second measuring device 22 is composed of a plurality of measuring devices such as a biological microscope, a stereomicroscope, an electronic balance for measuring the body weight and gonad weight of the bivalve, a weighing pan, tweezers, and a digital camera. The gonad development index is calculated manually or automatically based on the measured bivalve weight and gonad weight. The cooler 12 is, for example, a water tank cooler.

Further, the cooler 12 includes a seawater temperature adjusting means 121 for lowering the seawater temperature to a reference temperature or less when the measured seawater temperature exceeds a reference temperature suitable for cultivating bivalves, and the measured seawater temperature. A reference temperature adjusting means 122 for lowering the reference temperature is provided when the temperature is below the reference temperature and the calculated gonad development index exceeds the reference index.

[Reproductive gland development index]
The gonad development index is GSI (Gonado Somatic Index), and is calculated by dividing the weight of the gonad of the subject by the weight of the subject × 100 (%). In addition, the gonad development index may indicate the calculated GSI in 6 stages from 0 to 5. For example, "0" when the GSI is less than 10%, "1" when the GSI is 10% to 19%, "2" when the GSI is 20% to 29%, and "3" when the GSI is 30% to 39%. If it is 40% to 49%, it may be set to "4", and if it is 50% or more, it may be set to "5".

The degree of germ cell development can be defined for each of the 6 stages from 0 to 5 as follows.
0: Germ cells are not seen 1: Germ cells and egg mother cells can be observed 2: Germ cells are faintly recognized 3: Germ cells are developed and male and female can be distinguished 4: Germ cells are full 5: Germ cells are swelling

[Aquaculture method]
FIG. 2 is a flow chart of a bivalve aquaculture method according to an embodiment of the present invention. A method for culturing bivalve molluscs according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

First, the reference temperature of the seawater in the breeding tank 11 and the reference index of the gonad development index are set (step S101). In the present embodiment, the reference temperature is 18 ° C. In addition, the reference index is set to "3", which indicates that germ cell development is observed to the extent that males and females can be discriminated from the above-mentioned 6 steps of 0 to 5.

After that, periodically, that is, when a certain time has passed (step S111), the temperature of the seawater is measured by the first measuring device 21 (step S112). Steps S111 and S112 are referred to as a first measurement step. In the present embodiment, the fixed time is one hour.

When the temperature of the seawater is measured, the measured temperature of the seawater is compared with the reference temperature (step S121). Then, when the measured seawater temperature exceeds the reference temperature, the cooler 12 lowers the seawater temperature to or less than the reference temperature (step S122). Steps S121 and 122 are referred to as a seawater temperature adjusting step. Here, the lowering width may be lowered in increments of 0.1 ° C. or 1 ° C., or may be lowered in increments of 5 ° C., 10 ° C., or more. Specifically, the temperature of the seawater is measured every hour, and when the measured temperature of the seawater is 19 ° C., the temperature of the seawater is set to 18 ° C. or lower by the seawater temperature adjusting means 121 of the cooler 12, or it. Lower to:

Next, periodically, that is, when a certain period of time has passed (step S211), the weight and gonad weight of the bivalve S are measured by the second measuring device 22, and the gonad development index indicating the degree of germ cell development is calculated. do. (Step S212). Steps S211 and S212 are referred to as a second measurement step. In the present embodiment, the fixed time is one month.

When the bivalve gonad development index is calculated, the calculated bivalve gonad development index is compared with the reference index (step S221). Then, when the temperature of the seawater measured in step 112 is equal to or lower than the reference temperature and the calculated gonad development index of the bivalve mollusc exceeds the reference index, the reference temperature is lowered (step S222). Steps S221 and S222 are referred to as a reference temperature adjusting step.

Specifically, the bivalve gonad development index is calculated every month, and when the calculated bivalve gonad development index is "4" out of 6 stages, the reference temperature adjusting means 122 of the cooler 12 is used. Lower the reference temperature to 17 ° C or lower or lower. Here, the lowering width may be lowered in increments of 0.1 ° C. or 1 ° C., or may be lowered in increments of 5 ° C., 10 ° C., or more.

The method for culturing bivalve molluscs described above is merely an example, and the cycle for measuring the temperature of seawater and the cycle for calculating the gonad development index of bivalve molluscs may be appropriately changed during the cultivation.

[Experimental example]
The test results of the aquaculture test of Lajonkairia lajonii using the aquaculture method according to the present invention are shown below. For comparison, the test results of aquaculture tests using the conventional aquaculture method conducted in the outdoor tank area and the conventional tidal flat aquaculture method conducted in the coastal area of Inoura (offshore of the Inoura experimental site) are also included. show. The aquaculture period of this test example is from May 2015 to November 2015. In this test example, the temperature of seawater was measured in an hour cycle, and the calculation cycle of the bivalve gonad development index was set every month (1st of every month). The reference temperature was 18 ° C. and the reference index was “3”.

表１は、本発明に係る養殖方法を用いたアサリの養殖試験の試験結果である。上記の表１に示すように、水温（海水の温度）を常に基準温度である１８℃以下に管理している。また、１ヶ月毎に生殖腺発達指数を算出している。なお、本試験例においては生殖腺発達指数が基準指数である「３」を超える場合はなかったため、基準温度は下げていない。表１からも分かるように、本発明に係る養殖方法を用いた場合のアサリの生存率は１１月の時点で８８％と非常に高い値を示している。これにより、本発明により養殖中にアサリが受けるストレスが軽減されたり、産卵による体力の消耗が発生していないことが分かる。そして、アサリが斃死することが抑制され、安定した養殖を行うことができたことが分かる。

Table 1 shows the test results of the aquaculture test of Lajonkairia lajonii using the aquaculture method according to the present invention. As shown in Table 1 above, the water temperature (seawater temperature) is always controlled to be 18 ° C. or lower, which is the reference temperature. In addition, the gonad development index is calculated every month. In this test example, the gonad development index did not exceed the reference index "3", so the reference temperature was not lowered. As can be seen from Table 1, the survival rate of Lajonkairia lajonii when the culture method according to the present invention is used shows a very high value of 88% as of November. From this, it can be seen that the stress received by Lajonkairia lajonii during aquaculture is reduced by the present invention, and the exhaustion of physical strength due to spawning does not occur. Then, it can be seen that the death of Lajonkairia lajonii was suppressed and stable aquaculture was possible.

表２は、従来の陸上養殖方法を用いたアサリの養殖試験の試験結果である。上記の表２に示すように、水温が基準温度である１８℃以下に管理されていないため、水温は５月から２０℃を超え続けている。また、生殖腺発達指数も、水温が２５℃を超えた６月には「５」と非常に高い値となっている。そして、備考欄に示されるように、７月にはアサリの産卵が、８月には産卵後のアサリの衰弱が確認されている。表２からも分かるように、従来の陸上養殖方法を用いた場合のアサリの生存率は、産卵後の８月には１１％と非常に低い値を示しており、夏場にアサリの大量斃死が発生していることが分かる。

Table 2 shows the test results of the aquaculture test of Lajonkairia lajona using the conventional land-based aquaculture method. As shown in Table 2 above, since the water temperature is not controlled below the reference temperature of 18 ° C., the water temperature has continued to exceed 20 ° C. since May. In addition, the gonad development index is also very high at "5" in June when the water temperature exceeds 25 ° C. And, as shown in the remarks column, the spawning of Lajonkairia lajonii was confirmed in July, and the weakening of Lajonkairia lajonii after spawning was confirmed in August. As can be seen from Table 2, the survival rate of Lajonkairia lajonii when using the conventional land-based aquaculture method is a very low value of 11% in August after spawning, and mass mortality of Lajonkairia lajonii in the summer. You can see that it is occurring.

表３は、従来の干潟養殖方法を用いたアサリの養殖試験の試験結果である。上記の表３に示すように、水温が基準温度である１８℃以下に管理されていないため、６月から２０℃を超え続けている。また生殖腺発達指数も、水温が２２℃を超えた６月には「５」と非常に高い値となっている。そして、備考欄に示されるように、７月にはアサリの産卵が、８月には産卵後のアサリの衰弱が確認されている。表３からも分かるように、従来の干潟養殖方法を用いた場合のアサリの生存率も、産卵後の８月には２６％と非常に低い値を示しており、夏場にアサリの大量斃死が発生していることが分かる。

Table 3 shows the test results of the asari cultivation test using the conventional tidal flat cultivation method. As shown in Table 3 above, since the water temperature is not controlled below the reference temperature of 18 ° C, it has continued to exceed 20 ° C since June. The gonad development index was also very high at "5" in June when the water temperature exceeded 22 ° C. And, as shown in the remarks column, the spawning of Lajonkairia lajonii was confirmed in July, and the weakening of Lajonkairia lajonii after spawning was confirmed in August. As can be seen from Table 3, the survival rate of Lajonkairia lajonii when using the conventional tidal flat cultivation method is also very low at 26% in August after spawning, and mass mortality of Lajonkairia lajonii in the summer. You can see that it is occurring.

As shown in Tables 1 to 3 above, the survival rate of Lajonkairia lajonii in November was 88% when the culture method according to the present invention was used, whereas it was 4% when the conventional culture method was used. It can be seen that there is a remarkable difference of 17% when the conventional tidal flat aquaculture method is used.

The embodiment of the present invention described above is an example, and can be appropriately changed without departing from the spirit of the invention. For example, the first measuring device 21 and the second measuring device 22 may notify the cooling device 12 of the measurement result by wire or wirelessly, and the cooling device 12 may be notified from the first measuring device 21 or the second measuring device 22. The reference temperature may be changed or the seawater temperature may be changed automatically based on the measurement result of.

INDUSTRIAL APPLICABILITY The present invention is useful as aquaculture method and aquaculture device for land-based aquaculture of bivalves such as lajonkairia lajonii, shijimi, and hamaguri. It is useful as aquaculture method and aquaculture equipment that can suppress the death of Lajonkairia lajonii and perform stable aquaculture.

1 Aquaculture equipment 11 Breeding tank 12 Cooler 121 Seawater temperature adjusting means 122 Reference temperature adjusting means 21 First measuring device 22 Second measuring device S Bivalve T substrate

Claims (5)

It is a method of cultivating bivalves in a breeding tank filled with seawater.
The first measuring step of measuring the temperature of the seawater in the breeding tank by the first measuring device, and
When the measured seawater temperature exceeds the reference temperature suitable for bivalve breeding, the seawater temperature adjusting step of lowering the temperature of the seawater in the breeding tank to the reference temperature or lower by the cooler, and the seawater temperature adjustment step.
The second measurement step of measuring the body weight and gonad weight of the bivalve with the second measuring device and calculating the gonad development index indicating the degree of germ cell development, and
When the measured seawater temperature is equal to or lower than the reference temperature and the calculated gonad development index exceeds the reference index, the reference temperature adjustment step for lowering the reference temperature and the reference temperature adjustment step.
Bivalve farming methods including. The method for cultivating a bivalve according to claim 1, wherein the gonad development index is a GSI calculated by dividing the measured gonad weight of the bivalve by the body weight and rounded into 6 stages of 0 to 5. The method for culturing bivalve molluscs according to claim 1 or 2, wherein the reference temperature is 5 ° C to 28 ° C. The method for culturing bivalve molluscs according to claim 2, wherein the reference index is a step 3 indicating that germ cells have developed and males and females can be discriminated. A breeding tank filled with seawater and
The first measuring device for measuring the temperature of the seawater in the breeding tank and
A second measuring device that measures the body weight and gonad weight of the bivalve and calculates the gonad development index indicating the degree of germ cell development.
The cooler that adjusts the temperature of the seawater and
The cooler is a seawater temperature adjusting means for lowering the temperature of the seawater to a temperature equal to or lower than the reference temperature when the measured temperature of the seawater exceeds the reference temperature suitable for cultivating birch shells. When the temperature of the seawater is below the reference temperature and the calculated gonad development index exceeds the reference index, the reference temperature adjusting means for lowering the reference temperature and the reference temperature adjusting means.
Bivalve aquaculture equipment including.

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