JPS6054005B2 - Lobster farming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention primarily relates to a method for cultivating lobsters of the genus Homarus.

Attempts to farm shrimp in Japan have been carried out for a long time, targeting prawns.

However, the current aquaculture production of tiger shrimp in Japan is about 1,500 tons per year, which is only 1% of the total consumption of shrimp in the country. There are several possible reasons for the lack of increase in the production of Kuruma shrimp aquaculture.
In particular, it has been pointed out that prawns have a habit of burrowing into sand, and that they require a sandbox as the bottom material for aquaculture ponds, and that the environmental conditions of the sandbox deteriorate over time, which are technical bottlenecks. can. In this respect, if there is an epi species that does not require sand as a substrate, it would be ideal as a target species for aquaculture.

Spiny lobsters, which are distributed in the warm seas of Japan, live on rocky reefs and do not require sandboxes, but because they spend about 6 months floating as larvae, it is very difficult to produce seedlings, and at present there is no way to cultivate them. There is no possibility of it happening. The present inventor focused on lobsters of the genus Homar that live in the rocky areas of the northern Atlantic coast, and as a result of conducting research on their cultivation, was able to establish a practical method for cultivating this species for the first time.

Countries that fish for this species, such as the United States, Canada, the United Kingdom, and France, release decapitated larvae and farm their catch, but interest in aquaculture has only recently increased. It has just arrived, and full-scale aquaculture has not been successful. In April 1930, the present inventor transported brooding lobsters caught off the coast of Massachusetts, USA to Japan, and used them in experiments.

The emergence of larvae took place in May of the same year. To examine the rearing conditions for larvae, sick first-stage larvae were housed one by one in beakers with a capacity of 11, and the water temperature was 23.25 C for generations 5, 8, 12, 1 & 2, and the salinity was 13, 16, & 2. 20.0,
They were reared under conditions of various combinations of 23.5%, 27.0%, 30.0%, and 33.6% (on-site seawater). Breeding 2g! f
The survival rate between 12 and 1 was 40% at 5℃ and 80% at 8℃.
8.2 is 100% at 23°C and 20% at 25°C,
Also, when the water temperature is 20℃, the salinity is 13.5%, 20%, 16
．． 8% was 60%, and 20% or more was 100%.

In other words, lobster larvae are sensitive to low and high temperatures, and their optimum temperature range is thought to be 12 to 23°C, and their optimum salinity range is 20.0 to 33.6% (on-site natural seawater). Furthermore, within the appropriate temperature range, the higher the water temperature, the faster the growth.

Lobster molts its skin three times (strictly speaking, it molts once when it molts, so it molts four times) to become an adult 4th stage larva. The required time was 22, 14, 12, and 12 days. The cooling water temperature of lobsters in natural sea areas is relatively low at about 15°C, but growth is further improved by maintaining it in the range of 18 to 23°C. The fourth stage larva swims near the water surface with a pair of chelicerae extended forward, but when they encounter each other, they capture the other with their chelicerae, resulting in cannibalism.

The most effective way to prevent cannibalism was to breed phytoplankton and zooplankton in the breeding water. In other words, the reduction in illuminance in the rearing water due to the reproduction of phytoplankton prevents the larvae from collecting octopuses, and the reproduction of zooplankton constantly supplies abundant food to the larvae, both of which are effective in preventing attrition due to cannibalism. It is. A combination of diatoms and unicellular green algae as phytoplankton, and copepoda and Artemia as zooplankton was effective. Among these, in order to measure the reproduction of planktonic organisms such as diatoms and copepoda that exist in seawater with a water temperature of 15 degrees Celsius or less in the spring when lobsters are growing, it is necessary to adjust the water temperature. It was effective to raise the temperature to 18 to 23°C in a short period of time. Since cold seawater normally contains abundant nutrients in the spring, this heating operation allowed the growth of floating organisms to be maintained for two weeks in the presence of lobsters. Do the 5th stage larvae enter a benthic life? Stop swimming.

Although sand is not required as a substrate, gravel and key shells are effective in creating a hidden area. In particular, the numerous gaps formed when several key shells are stacked on top of each other at the bottom are suitable hiding places for larvae, and are also breeding grounds for various natural foods such as Annelida. By the end of the first year, the 5th stage larvae released into a pond with key shells on the bottom will have molted an additional 8 to 1 times and grown into 13 to 15 J] 18 young lobsters weighing 10 to 25 y. did. These young lobsters can continue to be raised in the same pond for the second year after overwintering, but it is currently advantageous to raise them individually in order to accurately grasp the number of lobsters and carry out planned rearing. .

Using a mesh with a mesh size of 2wrm, 10C1×10
(71t x depth 15C77! x depth 15c
ff1, 2 cum x 2 1 x depth 20C! Flll3h×3
Two mesh tanks each measuring 2 h x 2 h deep were constructed, and each tank housed one overwintered lobster weighing approximately 25 f, and the lobsters were kept in immersion water at a depth of 5.10 m.

At a water depth of 10 cm, all individuals molted their skin within two months after being housed, but at a water depth of 50 cm, they did not molt at the same time. In addition, in a net tank of 10 cm x 10 Crf1 x depth 0 at a water depth of 10 α, some individuals lost one of their chelicerae during molting, probably because the space was narrow compared to the size of the lobster. That is, in the second year
15Cff1×1 for normal growth of lobsters from the stage onwards.
A space of 10cm or more in depth is required. In the same way, the lobster sheds its skin further, and the first lobster weighs about 65y.
When it reaches this age, it is necessary to move it to a net tank of 25 cm x 2 cups x 2 hours deep and raise it. The above was an experiment to determine the size of the net tank to be used. In the second year, lobsters weighing approximately 25f were housed in the above-mentioned net tank, some of which were suspended on the surface of the seawater pond on land, and some of which were suspended from a raft set on the sea surface to a depth of 57n. and bred them. Water depth approx. 5
Sessile organisms are the easiest to breed in the sea up to Tr1, but they have traditionally been considered harmful to aquaculture organisms, as they cling to the mesh of cages, inhibit water exchange, and cause oxygen deficiency.

However, the attached organisms block the light and bring the illuminance inside the cage closer to the same conditions as inside the submarine shelter where lobsters live. Furthermore, since lobsters use their appendages to clean their cages themselves, there is no concern about oxygen depletion, and feeding is no longer necessary, which is advantageous for lobster farming. As the water depth increases to 5W1, the amount of attached organisms (food) decreases and becomes difficult to handle.

On the other hand, if the water depth is too shallow, the illuminance at the initial stage of culturing will be too bright, which is undesirable, and approximately 5 Tr1 is suitable for practical use. The former net tank was fed daily with crushed mussels as bait. In the latter net tank, a large number of adherent organisms such as snails and snails were observed to be attached to the mesh, and lobsters were observed actively preying on them, so no baiting was carried out. By the end of the second year, the former lobsters had molted 3-4 times and had grown to a weight of 105-155y1 18-1Wj. The latter lobster molted five times during the same period and grew into a second exposure lobster weighing 210V1. This means that
Sessile organisms are suitable as food for lobsters, and
It has been demonstrated that the mesh of the net tank is effective as a base for the growth of sessile organisms. In the third year, we used nets with 6 mesh sizes, 30cm in diameter and 20C7F in height! A cylindrical cage was made, one 20th stage lobster weighing approximately 210' was housed in each tank, and the cage was suspended from a raft to a depth of 5 WL.

By July, the lobster has molted once and weighs 310 kg.
y (21st period). By the end of the year, they had molted one more time and had matured, weighing 450 yd, and were now large enough to be expected to mate and lay eggs. Examples of the present invention will be shown below.

The attached figures show examples of equipment for carrying out the present invention, with Figure 1 being a longitudinal cross-sectional view of a breeding pond (or aquarium) for raising lobsters from the 4th stage to the brooding stage, and Figure 2 showing a net tank. Figure 3 shows a perspective view, and Figure A in Figure 3 is a side view explaining the state of use of the raft for rearing lobsters from the 15th stage onwards. , 3 is a net tank, 4 is a raft, 5
indicates a float, 6 indicates a net cage, 7 indicates a tether, 8 indicates the seabed, and 9 indicates the sea surface.

Example: In mid-May, 8,455 larvae were released from one incubating lobster over a period of 4 days.Of these, 1,475 first-stage larvae released on the third day were placed in a 1Tr filled with seawater.
It was housed in a water tank of L, x 0.5 TrL, x depth 0.5 TrL.

The water temperature at the time of water supply was 12.5°C, but it was heated to 20°C using a 500W heater and kept constant thereafter. In the aquarium, floating organisms such as diatoms and copepoda that were contained in the seawater when water was poured grew. In addition, frozen nettle was administered as supplementary food. After 12 days, the larvae had grown to the fourth stage, so they were picked up and transferred to an outdoor pond measuring 5rr1, x 2m x depth 0.5WL.

In this case, the number of fish transferred and recovered was 796 fish, and the survival rate from the time of lionization was 4% and 6%. Approximately 25 key shells were placed on the bottom of the pond per 1 d. The water was changed to the extent that the entire amount of water was replaced in one week. As feed, naturally collected sessile organisms such as snails and snails were administered once or twice a week. The sessile organisms could be easily collected by hanging a nylon robe with a diameter of 20 T1 m from a raft set on the sea surface and immersing it in the sea for several weeks. The fish were picked up in early December, but
The number of surviving fish was 576, and the weight ranged from 9.6 to 25.4 y (13th to 1st coral).

In the second year, we then selected 102 lobsters (14th, b stage) weighing 20-25 y and placed them in a size of d x 15 c.
One fish was housed in each tank (mesh size: 2 mm) with a depth of 20 cm and a depth of 20 cm, and the fish were suspended from a raft set on the sea surface to a depth of 5 Tr.

When the lobster grows to a weight of about 65 da (17th stage), it weighs 25 c! It was transferred to a mesh tank (mesh size 2Tfn) measuring n x 25cff1 x depth 20cm. A large number of attached organisms were always growing on the mesh of the net tank. Although no feeding was carried out, by the end of the year, 71 fish had molted five times and had grown to a weight of 210 da (2nd fish), and 31 fish had molted four times. In the third year, mesh size 6Tfn1 diameter 30C711 height 2
These lobsters were housed one by one in a 0CTn cylindrical cage and suspended from a sea surface raft to a water depth of 5Tr1.

Although no feeding was conducted, the lobsters had molted once and grown to 310y (21st stage) by July. After one more molt, they become sexually mature and are able to mate and lay eggs. The commercial viability of raising individual lobsters
This can be easily understood from the following calculation.

In other words, if you raise one lobster about 200y in a net tank of 25cm x 25cff1 x depth 20G, the water depth will be 1Tr.
L and 1X1. te1W
The production amount per ton is 0.2k9× =
0.25×0.25×0.2016
It will be k9.

This value is significantly higher than the production rate of 2k9/d for intensive cultivation of prawns using special facilities such as a double-bottom structure. Individual rearing is effective in preventing attrition due to cannibalism, but the disadvantage is that feeding requires time and effort. However, this problem was completely solved by housing lobsters in cages or net tanks, hanging them into the sea from rafts on the sea surface, and using the attached organisms attached to the nets as food. Fouling organisms are pests that grow on underwater structures and reduce their functionality. However, this research has shown that it is the best feed for lobsters, opening the door to its use. As a result, it will be possible to promote the cultivation of lobsters by hanging underwater in the rocky reef areas of our country's coast, where up until now no shellfish cultivation has been carried out. Needless to say, this kind of aquaculture method has not been considered at all even in the countries along the Atlantic coast.

[Brief explanation of the drawing]

The attached figures show examples of equipment for carrying out the present invention, with Figure 1 being a longitudinal cross-sectional view of a breeding pond (or aquarium) for raising lobsters from the 4th stage to the brooding stage, and Figure 2 showing a net tank. Figure 3 shows a perspective view of The side view and mouth view to explain the state of use of the raft for raising lobsters from the 15th stage onwards show a net cage. 1... Breeding pond, 2... Key shell, 3...
... Net tank, 4 ... Raft, 5 ... Float, 6 ... Net basket, 7 ... Mowing line, 8 ...
...bottom of the ocean, 9...sea surface.

Claims (1)

[Claims] 1. Lobster larvae from about the 1st stage to the 4th stage are reared in seawater with a water temperature of about 18 to 23°C in an aquarium in which floating organisms are bred, and the lobster larvae are raised from about the 4th stage to the 15th stage. The lobsters up to the age of 15 are reared in seawater in outdoor ponds or aquariums whose bottom sediment is mainly oyster shells, using mainly natural sea creatures as feed. Or, a method for cultivating lobsters, which comprises placing them in a net cage and cultivating them under the sea surface using the organisms attached to the net tank or the net cage as the main feed. 2. Claim 1, which is characterized in that lobsters of about 15 stages or later are housed in a net tank or net cage, suspended in the sea approximately 5 meters below the sea surface, and cultivated using the naturally attached organisms as the main food. lobster farming method.