JPH08140523A - Preservation of live crustaceans and apparatus therefor - Google Patents

Abstract

PURPOSE: To provide a method for preserving live crustaceans by which ammonia and floating suspended substances are reduced by regulating the pH in circulating water within the range of 8-9, the stress of the live crustaceans is reduced by indirectly spraying the circulating water thereon and the preservation period for the live crustaceans is prolonged. CONSTITUTION: This method for preserving live crustaceans is to include a pH increasing agent in circulating water and indirectly spray the resultant circulating water on the live crustaceans in spraying the circulating water on the live crustaceans housed in a container. The humidity in the container is kept within the range of 80-100% and the pH of the circulating water is kept within the range of 8-9. The method can be carried out by using an apparatus for preservation equipped with a preservation tank 10 having a holding container 11 for the crustaceans installed therein and sprayers 40 for spraying the circulating water containing the pH increasing agent provided in the preservation tank 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preserving live crustaceans such as prawns and crabs for a long period of time, and an apparatus used therefor.

[0002]

2. Description of the Related Art Storing crustaceans such as prawns, crabs, and shrimp for a long period of time in a live state is
It is an indispensable technology to move from the collection place to the farm pond, transport from the collection place to the consumption place, and provide the market with a large amount of collected shellfish according to the demand period. Is requested.

As a means for this purpose, for example, in the case of transporting live crustaceans, a method of storing live crustaceans in a tank of a live fish transport vehicle loaded with seawater, that is, a method of making the conditions almost the same as seawater, Another method is to put live shellfish in a container containing sawdust.

Since the live fish carrier has substantially the same conditions as the growth conditions of crustaceans, it can be kept in a good condition for a relatively long period of time. Only 20 kg / ton can be transported, and seawater is heavily contaminated, which is a cost problem. In addition, there are problems in purification treatment, oxygen supplementation, and temperature control regarding contamination of seawater due to excretion of live crustaceans.

Furthermore, in the method of using sawdust, there is a great difference from the original growth conditions of crustaceans.
Mortality increases with increasing temperature of sawdust, making it unsuitable for long-term storage and transportation.

In order to solve such a problem, for example, Japanese Unexamined Patent Publication (Kokai) No. 5-244861 discloses a technique for preserving live crustaceans in which water drops or water is sprayed on the live crust at all times or intermittently. It is disclosed.

According to this technique, crustaceans generally introduce water from the organs at the base of the legs and breathe with the gills, and the gill has the function of storing water even if it is raised to the land.
It was devised by paying attention to the fact that new water can be introduced into the gill and survive by supplying water little by little from the outside without directly immersing it in seawater.

[0008] As described above, the water stored in the gills of crustaceans can be exchanged little by little by spraying the seawater in the form of drops or mist, and the seawater can be stored for a relatively long time with little seawater. It becomes possible.

[0009]

However, even with such a storage method, a satisfactory result is not always obtained, and according to the experiments conducted by the present inventor, death may occur in several days depending on the conditions. It was a situation that was

Therefore, an object of the present invention is to improve the above-mentioned technique of spraying seawater in a storage tank in a mist state, and to extend the storage period of live crustaceans.

[0011]

As a result of various experiments, the present inventor has conducted various experiments on the cause of death in a short period of time. It was found to be due to the propagation of contained bacteria, contamination of seawater with pathogenic bacteria, excretion of live crustaceans themselves, generation of ammonia by body fluids, floating suspension (organic matter), and exfoliation of body mucus. .

The present invention has been completed based on the above findings, and in a method for preserving live water shells in which the circulating water is sprayed onto the live shellfish contained in a container, the circulating water is sprayed into the circulating water when spraying the circulating water. The method is characterized in that a pH raising agent is included and the live shellfish is indirectly sprayed.

Here, the pH-increasing agent is an agent that facilitates the reduction of excretions from live crustaceans, ammonia and suspended suspensions that cause death by death from body fluids, such as sodium hydrogen carbonate and lime. Although it is possible to use an alkali source of sodium bicarbonate, sodium hydrogen carbonate is preferable because it is not toxic to crustaceans, is lightweight and is easily available.

At this time, the humidity in the container is 80 to 100.
%, And the pH is preferably in the range of 8-9.

By increasing the pH in the circulating water,
Ammonium ions (NH ₄ —N) in the circulating water are transformed into non-dissociated ammonia (NH ₃ ). This non-dissociated ammonia is easily scattered in the air by physical stimulation such as aeration and stirring. Non-dissociated ammonia is affected by water temperature, pH, etc., and when the pH is 6 or less, most of it is ammonium ions, and when the pH is 11 or more, most of it becomes non-dissociated ammonia. A pH of 8-9 is desirable because it affects physiology.

On the other hand, in order to prevent sudden environmental changes in seawater, it is known that it is desirable to keep the alkalinity of seawater having a buffering capacity above a certain level. In the metabolic process of nitric acid bacterium that decomposes substances and the like, bicarbonate in seawater (H ₂ CO ₃ ) is consumed, pH is lowered, and alkalinity is reduced. On the other hand, by adding a pH raising agent such as sodium hydrogen carbonate, the weak acid in the pH raising agent also has the effect of increasing the amount of weak acid in seawater and preventing a decrease in alkalinity.

Further, according to the test by the present inventor, particularly in the case of tiger prawns, spraying the cooled seawater directly on the tiger prawns causes physical peeling of the body mucus that protects the surface of the crustaceans from the infection of diseases. The fungus invades inside the crustaceans due to the decrease in mucus secretion function due to the stress caused by falling or dropping of water drops, which causes mortality, which is caused by indirect spraying of circulating water. Solvable.

Furthermore, in the case of live crustaceans, if the temperature is too high, metabolism becomes active and the animals move around,
It violently pollutes the circulating seawater, consumes a large amount of oxygen in the seawater, weakens the vitality of the crustaceans, and if the temperature is too low, the crustaceans cannot sustain their lives. Therefore, the temperature is 10
-13 ° C is desirable.

The above-mentioned storage method is carried out by a storage device for live crustaceans equipped with a storage tank containing a container for holding live crustaceans and a spraying device for spraying circulating water containing a pH raising agent in the storage tank. it can.

Here, the storage tank is made of synthetic resin such as vinyl chloride and FRP. Its basic structure is to prevent outside air from entering and to discharge vaporized ammonia. It is equipped with a container and a spraying device for circulating water.

Further, an appropriate structure can be added to the storage tank depending on the purpose of use of the storage device. For example, when storing crustaceans as fishing baits, synthetic resin is used to make the front transparent so that the inside can be seen, and crustaceans are frequently taken in and out, so the spray of circulating water stops when the door is opened. Such a structure can be adopted. When the storage device is transported by ship, seawater as circulating water can be exchanged, so it is desirable to add a cooling device to the storage tank when exchanging seawater.
In addition, when storing crustaceans for market adjustment, it is desirable to use a tall storage tank to increase the amount of storage.

As the spraying device, there is provided a nozzle mechanism for indirectly spraying the circulating water to the stored live shellfish, or a water jetting device for jetting the circulating water and air from a direction intersecting with the jetted water. It may be provided with an air nozzle that blows it out to scatter water in a mist state, and further, it may be provided with a sterilizer for sterilizing circulating water, and / or a filter for filtering bacteria in the air.

Here, as a nozzle mechanism for indirectly spraying circulating water on live crustaceans, a partition for directing the nozzle toward the inner wall side of the storage tank or for blocking direct irradiation to the live crustaceans in the jet direction of the nozzle It can be configured by providing a plate.

It is desirable that the water ejection direction of the water ejection device and the air ejection direction of the air nozzle intersect each other at a right angle so that the water ejection speed becomes maximum. It is desirable that a plurality of the water jetting devices be provided inside the storage tank so that convection occurs in the storage tank.

As the circulating water sterilizer, ozone, a filter, etc. can be used as long as they can sterilize bacteria, but the ultraviolet irradiation device is particularly easy to install and inexpensive. Is desirable.

The filter for filtering the bacteria in the air is for filtering the dust, dust, and other bacteria in the air to prevent the natural generation of microorganisms, and ozone or the like can be used. A filter is desirable because it can be installed.

In addition, organic substances such as suspended suspensions, phytoplankton and zooplankton contained in circulating water are filtered by using a simple filter material (trade name: Esplansoil) which is attachable and washable, and Decrease
The water jetting device can be prevented from becoming blocked.

[0028]

[Operation] By including a pH raising agent in the circulating water,
Ammonia, reduce suspended suspension and maintain alkalinity. In particular, by maintaining the pH of the circulating water at 8 to 9, ammonium ions in the circulating water are changed to non-dissociated ammonia. This non-dissociated ammonia is easily scattered in the air by physical stimulation such as aeration and stirring, so that the amount of ammonia in the circulating water is reduced.

The sodium bicarbonate used as a pH raising agent maintains the alkalinity by supplementing sodium bicarbonate consumed in the metabolic process of nitric acid bacteria that decomposes organic matter such as excretions of live crustaceans. To act.

By indirectly spraying circulating water, physical exfoliation of body mucus covering the surface of crustaceans and abnormal secretion of body mucus due to stress are prevented, and the body is a means of protection from bacteria. The mucus can be secured.

When the temperature of the circulating water is high, the metabolism of the live crustaceans becomes active, and the circulating water becomes dirty by moving around, but by keeping the temperature of the circulating water at 10 to 13 ° C, the circulating water becomes dirty. In addition to preventing it, it also suppresses the consumption of oxygen in the circulating water and enhances the vitality of live shellfish.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be specifically described below with reference to the embodiments shown in the drawings.

FIG. 1 is a side view of a live crustacean storage device according to an embodiment of the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a front view of the same, and the internal structure of the storage tank is shown in a sectional view. Is shown.

Reference numeral 10 is a storage tank made of FRP, 20 is an air blowing device for introducing air into the storage tank 10, and 30 is the circulating seawater accumulated at the bottom of the storage tank 10 and spouting into the storage tank 10. It is a water jetting device.

The storage tank 10 is provided with a slope at the top so that water droplets do not drip, has a structure capable of preventing the invasion of outside air, and discharging vaporized ammonia to the outside. A partition plate 12 having a class holding container 11 and preventing spray water from directly contacting the live shellfish on the outer peripheral part thereof.
Is provided. 13 is a simple filter material (trade name: Esplan Soil), which is disposed below the live crustacean holding container 11 and filters organic substances contained in seawater, and can be removed and washed.

The cage 14 containing the live crustaceans has a large bottom area and a low height so that the live crustaceans do not overlap each other. As shown in FIG. The frame 15 is supported diagonally. As a result, the water droplets attached to the basket 14 move outward along the inclination of the basket 14 and flow downward from the support frame 15, so that the droplets can be prevented from directly dropping on the crustaceans.

Reference numeral 16 denotes a discharge port provided at an upper position of the storage tank 10 for discharging ammonia vaporized in the storage tank 10.

The air blowing device 20 includes a blower 21,
An air sterilizer 22 having a filter (not shown) for preventing bacteria from entering the storage tank 10 is provided, and the tip of the air sterilizer 22 is connected to an air pipe 23 provided in the storage tank 10. Has been done.

The water jetting device 30 includes a pump 31 connected to a water reservoir at the bottom of the storage tank 10, an ultraviolet irradiation sterilizer 32 provided upstream of the pump 31, and a circulating water temperature of 10 to 10.
A water temperature management device 33 for maintaining the temperature at 13 ° C. is provided, and the water temperature management device 33 is connected to a seawater pipe 34 provided in the storage tank 10.

Reference numeral 35 denotes a pH raising agent mixing device for mixing the pH raising agent into the circulating water. Sodium hydrogen carbonate is put in the pH raising agent mixing device 35, and this is automatically mixed in the circulating water. The mixing amount is
The pH of the circulating water is measured by a sensor (not shown),
The pH is automatically controlled to be in the range of 8-9.

FIG. 5 is a view showing a main part of the spraying device 40. As shown in FIG. 5, a hose 34a communicating from the inside to the outside is provided on the side surface of the seawater pipe 34 and is adjacent to the seawater pipe 34. An air outlet 23 a is formed on the upper surface of the air pipe 23. With such a structure, the pressure of the seawater blowing port 34b of the hose 34a is reduced by the air blown from the air blowing port 23a, and the seawater in the seawater pipe 34 is discharged from the seawater blowing port 34b.
And is blown away by the air to form a fine mist, which is supplied into the storage tank 10.

Here, the seawater outlet 34b is preferably narrow so that the seawater can be easily pushed up from the seawater pipe 34. Further, the intersection angle between the air blowing direction of the air blowing port 23a and the seawater blowing direction of the seawater blowing port 34b is set to 90 ° so that the water ejection speed is high near the seawater blowing port 34b.

It is preferable that a plurality of the spraying devices 40 are provided inside the storage tank 10 so that convection occurs in the storage tank 10. In this embodiment, one spraying device 40 is arranged at each of the four corners of the storage tank 10. .

In the above structure, the live shellfish in the basket 14 are stored in the multi-stage live shellfish holding container 11, and seawater is sprayed into the storage tank 10 as circulating water. At that time, since sodium hydrogen carbonate, which is a pH raising agent, is mixed in the circulating water, ammonia generated from the excrement of live crustaceans is vaporized, and the exhaust port 16
Can be discharged from. This gives ammonia,
Organic matter is reduced, alkalinity is maintained, and the life span of live crustaceans can be significantly extended.

The sprayed circulating water is separated by the partition plate 12.
Prevents the spray water from directly contacting live crustaceans,
Thereby, physical peeling of body mucus and stress of live shellfish are reduced, and the body mucus can be kept in a good state.

It should be noted that such a storage device can be installed in a warehouse or the like, or can be installed in a live fish carrier.

An experiment for preserving prawns was actually carried out using the above apparatus.

[Experimental Example 1] Using the above storage device, the pH of circulating water and ammonia were measured without using a simple filter medium and adding a pH raising agent. This experiment confirmed the effect of direct spraying.

Further, the prawns submerged in the sand were directly caught by hand, and the prawns were put in two baskets of 10 fish each and placed in a 70-liter water tank at the upper and lower stages. The seawater spray port was directed to the upper part so that the spray was directly applied to the upper part. The seawater used was cooled in the order of 20 ° C, 17 ° C, and 14 ° C. The results are shown in Table 1.

[0050]

[Table 1]

As shown in Table 1, an increase in ammonia in the circulating water was observed. In addition, in the upper part where the direct spray water was applied, more deaths were observed than in the lower part, and it was found that the direct spray had an adverse effect.

[Experimental Example 2] Using the above-mentioned storage device, simple filter media were added without adding prawns, a pH raising agent was added, and ammonia in circulating water was measured. In addition, ammonium chloride is added to circulating water by adding ammonium chloride in advance.
It was adjusted to be 0 ppm. Table 2 shows the results.

[0053]

[Table 2]

As shown in Table 2, ammonia was not detected after 48 hours by adding the simple filter medium and the pH raising agent.

[Experimental Example 3] The prawns submerged in the sand were directly caught with an electric rod by hand, and the prawns 70
In the liter water tank, 34 fish baskets were placed in the upper basket and 22 fish baskets were placed in the lower basket. The seawater used was not cooled because the temperature was low in winter. The results are shown in Table 3.

[0056]

[Table 3]

As shown in Table 3, almost one week passed without dying. In addition, the death from death occurred in the upper and lower rows in the same way after one week had passed.

[Experimental Example 4] The water temperature of the used prawns was 1
It was stored in a 6 ° C water tank. As a pretreatment before the start of the experiment, the water temperature of seawater was cooled in two stages of 15 ° C and 13 ° C in order to acclimate the prawns to a low temperature, and then,
The water was kept at 13 ° C for 24 hours. Kuruma shrimp put 58 fish in one basket. The results are shown in Table 4.

[0059]

[Table 4]

As shown in Table 4, as in Experimental Example 3, almost no death occurred in about one week.

[Experimental Example 5] The prawns used had a water temperature of 2
It was stored in a water tank at 8 ° C. As a pretreatment before the start of the experiment, in order to acclimate the prawns to a low temperature, the seawater temperature was 26 ° C, 22 ° C, 18 ° C, 15 ° C. It was cooled in stages and then left at a water temperature of 13 ° C. for 24 hours.
Kuruma shrimp put 73 fish in one basket. The results are shown in Table 5.
Shown in

[0062]

[Table 5]

As shown in Table 5, mortality was observed from the 2nd day, and it continued intermittently thereafter.

From the above experimental results, the death in the container was 28 ° C for about one week when the pond water temperature was 20 ° C or lower.
It turned out that it can be seen from the second day on C and above.

[0065]

According to the present invention, the following effects can be obtained.

(A) By including a pH raising agent in the circulating water to be sprayed, it is possible to reduce ammonia and suspended suspension, maintain alkalinity, and extend the shelf life of live shellfish.

(B) By indirectly spraying the circulating water on the live crustaceans, the stress of the live crustaceans can be reduced and the life of the live crustaceans can be extended.

[Brief description of drawings]

FIG. 1 is a side view of a live crustacean storage device according to an embodiment of the present invention.

2 is a plan view of the live crustacean storage device of FIG. 1. FIG.

3 is a front view showing the internal structure of the live crustacean storage device of FIG. 1. FIG.

[Fig. 4] Fig. 4 is a diagram showing a setting situation of a cage for accommodating live crustaceans.

FIG. 5 is a diagram showing a main part of a spraying device.

[Explanation of symbols]

 10 Storage Tank 11 Live Crustaceous Container 12 Partition Plate 13 Simple Filter Material 14 Basket 15 Support Frame 16 Exhaust Port 20 Air Blowing Device 21 Blower 22 Air Sterilizer 23 Air Pipe 23a Air Blowout 30 Water Jet Device 31 Pump 32 Sterilizer 33 Water temperature management device 34 Seawater pipe 34a Hose 34b Seawater outlet 35 pH raising agent mixing device 40 Spraying device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiki Nakayama 13-4 Otemachi, Ogurakita-ku, Kitakyushu, Fukuoka Prefecture Kyushu Bio Co., Ltd.

Claims (8)

[Claims] 1. A method for preserving live shellfish in which circulating water is sprayed on live shellfish contained in a container, wherein a pH raising agent is included in the circulating water when spraying the circulating water. How to store live crustaceans. 2. The method for preserving live shellfish according to claim 1, wherein the circulating water is indirectly sprayed onto the live shellfish contained in the container. 3. The method for preserving live crustaceans according to claim 1, wherein the pH of the circulating water is in the range of 8-9. 4. The method for preserving live shellfish according to claim 1, wherein the temperature of the circulating water is 10 to 13 ° C. 5. A storage tank containing a live crustacean holding container,
A storage device for live crustaceans, comprising a spraying device for spraying circulating water containing a pH raising agent in the storage tank. 6. The storage device for live crustaceans according to claim 5, wherein the spraying device includes a nozzle mechanism that indirectly sprays the circulating water onto the stored live shellfish. 7. The spraying device comprises a water jetting device for jetting the circulating water, and an air blowing device for scattering the jetted water in a mist state.
Storage device for live crustaceans according to 6. 8. The storage device for live shellfish according to claim 7, further comprising a sterilizing device for sterilizing the circulating water, and / or a filter for filtering bacteria in the air.