Method for farming cephalopods
By maintaining a stable cephalopod school composition and controlling environmental conditions, the survival rate of cephalopods in artificial rearing environments is substantially increased, addressing the limitations of conventional cultivation methods.
Patent Information
- Application Number
- JP2024039335
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-13
- Publication Date
- 2025-09-29
- Estimated Expiration
- 2044-03-13
AI Technical Summary
Conventional methods for cultivating cephalopods, such as those described in Non-Patent Document 1, have not been able to sufficiently increase the survival rate of cephalopods in an artificial rearing environment.
The method involves raising a school of cephalopods in an artificial breeding environment without merging it with other schools for a predetermined period after hatching, limiting the number of mergers to three or less, and maintaining a temperature of 15°C to 30°C, preferably 20°C to 26°C, using free-flowing seawater, and ensuring a total cephalopod number of 200 or less.
This method significantly increases the survival rate of cephalopods by minimizing stress and conflicts, reducing cannibalism, and maintaining a stable school composition, thereby enhancing survival rates and enabling sustainable aquaculture.
Smart Images
Figure 2025140145000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a method for cultivating cephalopods. [Background technology]
[0002] Animals belonging to the class Cephalopoda of the phylum Mollusca, such as squid and octopus (hereinafter sometimes referred to as "cephalopods"), are widely eaten due to their unique texture and flavor, as well as their high nutritional value.
[0003] Due to high demand and high commercial value, attempts have been made to cultivate cephalopods (see, for example, Non-Patent Document 1). Non-Patent Document 1 discloses various findings regarding the cultivation of several major cephalopods, including the commercially valuable bigfin reef squid. For example, Non-Patent Document 1 discloses findings regarding the maintenance and management of broodstock for cultivation, hatching, water quality management and feed during cultivation, etc. [Prior art documents] [Non-patent literature]
[0004] [Non-Patent Document 1] Cephalopod Culture, edited by Jpse Leglesias, Lidia Fuentes, Roger Villanueva, Springer Publishing, pp. 315-348 Summary of the Invention [Problem to be solved by the invention]
[0005] However, conventional methods such as those described in Non-Patent Document 1 have not been able to sufficiently increase the survival rate of cephalopods in an artificial rearing environment. Therefore, an object of the present invention is to provide a method for cultivating cephalopods that can sufficiently increase the survival rate of cephalopods in an artificial rearing environment. [Means for solving the problem]
[0006] The present inventors have conducted extensive research to achieve the above object, and have newly discovered that when raising a group of cephalopods in an artificial breeding environment, the survival rate of the cephalopods can be significantly increased by minimizing the number of groups of cephalopods that merge with other groups, leading to the completion of the present invention.
[0007] In other words, the present invention aims to advantageously solve the above-mentioned problems, and is a method for cultivating cephalopods, which includes [1] raising a school of cephalopods in an artificial breeding environment without merging the school with other schools different from the school of cephalopods for a predetermined period of time immediately after the cephalopods hatch, or, if merging, so that the number of times of merging is three or less. This aquaculture method can sufficiently increase the survival rate of cephalopods in an artificial rearing environment.
[0008] [2] In the method for cultivating cephalopods described in [1] above, it is preferable that the cephalopods are not allowed to merge with other shoals different from the shoal for a predetermined period of time immediately after hatching.
[0009] [3] In the method for cultivating cephalopods according to [1] or [2] above, the school of cephalopods is preferably a school containing cephalopod individuals that have hatched together.
[0010] [4] In addition, in the method for cultivating cephalopods according to any one of the above [1] to [3], it is preferable to cultivate the cephalopods while running seawater over them.
[0011] [5] In the cephalopod culturing method according to any one of [1] to [4] above, the temperature of the seawater is preferably 15°C or higher and 30°C or lower.
[0012] [6] In the method for cultivating cephalopods according to any one of [1] to [5] above, it is preferable that the total number of cephalopods is 200 or less over the predetermined period. [Effects of the Invention]
[0013] According to the present invention, a method for cultivating cephalopods can be provided that can sufficiently increase the survival rate of cephalopods in an artificial rearing environment. [Brief explanation of the drawings]
[0014] [Figure 1] 1 is a bar graph showing the survival age in days for each group. [Figure 2] 1 is a graph plotting the average survival rate for every 7 days when the mice were reared from 0 to 91 days of age. DETAILED DESCRIPTION OF THE INVENTION
[0015] Hereinafter, an embodiment according to an example of the present invention will be described in detail.
[0016] (Cephalopod farming methods) The cephalopod farming method of the present invention is characterized in that, when rearing a group of cephalopods in an artificial rearing environment, it involves rearing the group without allowing other groups different from the group mentioned above to merge with the group during a predetermined period of time immediately after the cephalopods hatch, or limiting the number of mergers to three or less. That is, the group that has been artificially reared from the beginning to be referred to as group A is not allowed to merge with other groups different from group A (e.g., groups B1, B2, ... B5), or limiting the number of mergers to three or less, thereby minimizing mixing of group A with other groups. While it is unclear why such a method can increase the survival rate of cephalopods in an artificial rearing environment, it is thought to be due to the fact that cephalopods can be highly social. In other words, by "fixing" the multiple individual members of a group immediately after hatching, excluding a decrease in the number of individuals due to death, and minimizing the entry of new individuals into the group, it is believed that stress that may arise from conflict between individuals can be suppressed and the probability of events that may reduce survival rates, such as cannibalism, can be reduced. In the cephalopod farming method of the present invention, it is most preferable to raise cephalopods as a so-called independent group without merging with other groups for a predetermined period of time immediately after hatching. Even if other groups are merged with a group that has been raised from the beginning to form a mixed group, it is preferable that the number of mergers be two or less, and more preferably one or less. In this way, by minimizing the merger of other groups with a group that has been raised from the beginning, the survival rate of cephalopods can be further increased. As a result, it is believed that it will be possible to raise cephalopods for generations.
[0017] The cephalopod farming method of the present invention is particularly applicable to cephalopods, particularly cuttlefish and cuttlefish, which belong to the class Decapoda of the subclass Cephalopoda of the phylum Mollusca. It is particularly applicable to the oval squid (Sepioteuthis lessoniana), which is classified as a cuttlefish. In the following explanation, the cephalopod will be described as a "oval squid." Here, the oval squid is a type of squid belonging to the genus Sepioteuthis, family Pectenidae, of the class Sepioteuthis. The oval squid is a large squid found along the coast of Japan and is popular for consumption. The oval squid is said to be the most expensive of all squids, and the large white squid type is particularly expensive and is mainly used in sushi restaurants and high-end restaurants.
[0018] <Features> Typically, the body length of the bigfin reef squid is approximately 40-45 cm. Large specimens can reach body lengths of over 50 cm and weigh over 6 kg. The bigfin reef squid's body is rounded, with semicircular fins along the edge of the body. The appearance of the bigfin reef squid is somewhat similar to that of a cuttlefish, but its carapace is thin and transparent. Mature, reproductively active males have scattered short white horizontal stripes on their backs, while females have indistinct horizontal stripes, which generally serve as an indicator of sexual differentiation. The distribution of bigfin reef squid is widespread, centered around the equator, from Japan to northern New Zealand, and from Hawaii to South Africa. The average lifespan of a bigfin reef squid is approximately one year. Furthermore, as evidenced by their distribution, bigfin reef squid tend to prefer relatively warm water temperatures.
[0019] <Water temperature and quality> The temperature of seawater when rearing bigfin reef squid is preferably 15°C or higher, more preferably 20°C or higher, and preferably 30°C or lower, and even more preferably 26°C or lower. If the water temperature is above 30°C, there is a risk that the eggs will not hatch. Furthermore, by keeping the water temperature at 26°C or lower, the hatching rate can be increased. By keeping the water temperature at 15°C or higher, more preferably 20°C or higher, predation by bigfin reef squid can be promoted. By keeping the water temperature at 20°C or higher, the hatching rate of bigfin reef squid can be increased. For example, at a water temperature of 25°C, bigfin reef squid eggs will hatch in about one month.
[0020] Furthermore, it is preferable that the seawater used when raising bigfin reef squid is free-flowing seawater. Furthermore, it is preferable that seawater is supplied to and discharged from the aquarium so that the free-flowing seawater creates a water current within the breeding tank. In this way, the tank can be kept clean at all times. Free-flowing seawater is also economical as it does not require electricity for water temperature control, etc. Furthermore, when cultivating bigfin reef squid in their habitat, the squid can be raised in the seawater of their natural environment, which provides a good growth environment. Bigfin reef squid may also be raised in a fish pen.
[0021] Spawned eggs typically hatch after a developmental stage spanning approximately three to four weeks. For eggs hatched from egg masses laid on the same spawning date, the time required from the start of hatching to the end of hatching is typically approximately one week. In this specification, the date on which hatching begins is referred to as the hatching date. Here, the cephalopod school reared using the cephalopod farming method of the present invention is preferably a school containing cephalopod individuals that hatched together. Specifically, in this specification, "cephalopod individuals hatched together" refers to multiple cephalopod (Volvoviviparous squid) individuals that hatched simultaneously in the same rearing tank (including a fish pen; the same applies hereinafter). These multiple individuals may be individuals hatched from eggs spawned by a single female. By rearing these individuals that hatched together for a predetermined period of time immediately after hatching, stress caused by interactions between individuals can be reduced and survival rates can be increased. The predetermined period of time from immediately after hatching may be, for example, the rearing period from the time of hatching until the farmed Volvoviviparous squid is shipped. In another embodiment, the predetermined period may be the period until the hatched individuals are transferred to a tank for rearing mature individuals. The rearing period until the farmed bigfin reef squid is shipped is not particularly limited and can be changed as needed, but may be, for example, from 90 days to 200 days.
[0022] It is preferable to feed hatched cephalopod larvae (juvenile squid in the case of bigfin reef squid) a combination of dead bait and live bait for a period of 20 to 100 days from the date of hatching. Feeding live bait requires more labor than feeding dead bait, making it less convenient. For this reason, it is preferable to transition to dead bait as soon as possible, but completely transitioning to dead bait in a short period of time, such as one week, may impair the survival rate of the bigfin reef squid. Therefore, in one aspect, it is preferable to increase the survival rate of the bigfin reef squid by transitioning to dead bait after a relatively long transition period as described above.
[0023] <Breeding> Because bigfin reef squids have a habit of jumping out of the water, in order to increase their survival rate, it is preferable to select the height of the tank and water surface when raising bigfin reef squids so that the walls are sufficiently high above the water surface. For example, in the case of juvenile squids, it is preferable to ensure walls that are 10 cm or more high above the water surface, and in the case of adults, it is preferable to ensure walls that are 40 cm or more high above the water surface.
[0024] <Breeding density> Cephalopod rearing densities vary depending on the size and maturity of the squid, but are generally between 200 and 2,000 individuals / m at hatching. 3 , 2-20 individuals / m at maturity 3 The lower limit of the rearing density is not particularly limited, but for example, it is 0.05 individuals / m during the breeding season. 3 The rearing density of cephalopods can vary depending on the growth and death of the cephalopods, but by controlling it to be equal to or less than the upper limit, the survival rate of the cephalopods can be further increased. Note that these upper and lower limits of rearing density can also be applied to juvenile squid immediately after hatching. The rearing density can be adjusted as needed by moving the rearing tanks and changing the tank size as the squid grow.
[0025] <Total Cephalopod Population> The total number of cephalopods is preferably 200 or less, more preferably 100 or less. The total number of cephalopods refers to the total number of cephalopods present in the breeding tank or fish preserve. The lower limit of the total number of cephalopods is not particularly limited, but it can be, for example, 5 or more. The total number of cephalopods may naturally decrease due to the death of individuals reared in the breeding tank. Therefore, it is preferable that the number of individuals immediately after hatching, i.e., the number of individuals at the start of aquaculture, be within the above range. Furthermore, if a different school B1 is added to a breeding tank already rearing school A, the total number of individuals of school A and school B corresponds to the "total number of cephalopods." If the total number of cephalopods in the breeding tank at the start of aquaculture is within the above range, the survival rate of cephalopods in an artificial rearing environment can be further increased. [Example]
[0026] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.
[0027] Example 1 The influence of mixed populations on the aquaculture techniques of Okinawan bigfin reef squid The cephalopod selected for rearing was the bigfin reef squid (Sepioteuthis lessoniana, Ferussac in Lesson, 1830). The breeding equipment used a "free-flowing system," drawing seawater from a depth of 20 meters off the coast of Seragaki Port in Onna Village, Okinawa Prefecture, and pumping it up to the roof of the facility for distribution to each tank. The seawater was filtered through sand to remove organisms and solids. The facility is approximately 300 meters from the seawater intake pump room, which passes through a second pump room. After passing through all the breeding tanks, the seawater was returned to the sea via an outlet and a settling pond. The water temperature in Onna Village ranges from approximately 20°C to 30°C, but varies depending on the season and year, and was monitored 24 hours a day using a logger. The free-flowing system uses no copper, chemicals, or drugs to protect the marine environment and maintain the health of the cephalopods.
[0028] The eggs of the bigfin reef squid were collected from Fuchaku Beach in Onna Village. The eggs were carefully transported to the facility and placed in an aquarium, where they were left to hatch.
[0029] The initial feed after hatching consisted of live isazamemi (live bait) and frozen preserved whitebait (dead bait). As the squid grew, the dead bait was changed from frozen whitebait to frozen silver-stripe round herring used for fishing bait, and once the transition to dead bait was achieved, silver-stripe round herring was fed as the staple food. The size of the breeding tanks was changed as the squid grew, improving the precision of breeding. In this way, by changing the size of the tanks as the squid grew, the breeding density was maintained within an appropriate range and various problems were quickly addressed.
[0030] The effects of mixing 34 groups of 1,239 individuals from a population of captive-raised bigfin reef squid in a breeding experiment were examined. Mixed groups were assessed by dividing groups that had been mixed at least once immediately after hatching into "mixed groups," while groups that had been reared with only the same population from hatching into "independent groups." The survival rates and lengths (number of days of survival) of these groups were compared every seven days from 7 to 91 days of age. 16 groups of 500 individuals were compared in the mixed groups, while 18 groups of 739 individuals were compared in the independent groups.
[0031] Experimental results In the mixed group, the shortest survival time was 9 days, the longest survival time was 139 days, and the mean survival time was 48.875 days with an SD of 43.17 days. In contrast, the independent group had a shortest survival time of 50 days, a longest survival time of 234 days, and a mean survival time of 127 days with an SD of 52.92 days. Figure 1 shows a bar graph in which the 16 mixed groups and the 18 independent groups were assigned identification numbers in order of survival time, with the group identification number on the horizontal axis and the survival time on the vertical axis. Figure 1 shows that the independent groups had a significantly longer survival time than the mixed group. The average survival rate by age for the mixed group was 59% at 7 days, 38% at 14 days, 25% at 21 days, 21% at 28 days, 17% at 35 days, 14% at 42 days, 13% at 49 days, 12% at 56 days, 10% at 63 days, 9% at 70 days, 8% at 77 days, 8% at 84 days, and 7% at 91 days. In contrast, the survival rates for the independent groups were 80% at 7 days, 64% at 14 days, 55% at 21 days, 47% at 28 days, 41% at 35 days, 38% at 42 days, 32% at 49 days, 29% at 56 days, 27% at 63 days, 23% at 70 days, 22% at 77 days, 20% at 84 days, and 18% at 91 days (see Figure 2). In Figure 2, the solid line shows the mean survival rate curve for the independent group, and the dashed line shows the mean survival rate curve for the mixed group. Figure 2 shows that the mean survival rate of the independent group exceeded that of the mixed group at all ages. Furthermore, it was observed that the mean survival rate and mean survival days increased as the number of times the flocks were mixed immediately after hatching decreased (2 times, 1 time, 0 times).
[0032] The results of this experiment demonstrated that the members of a school have an impact on artificial rearing of bigfin reef squid. The survival time and seven-day survival rate of schools with significantly mixed school members were significantly higher in schools reared with the same members from hatching, demonstrating the school's stability. Maintaining consistent school composition is thought to reduce stress and increase feeding motivation in artificial rearing, making it a crucial factor for sustainable bigfin reef squid aquaculture. Furthermore, this cephalopod rearing method, which significantly improves survival rates, suggests that it may be possible to rear cephalopods for generations. [Industrial Applicability]
[0033] According to the present invention, a method for cultivating cephalopods can be provided that can sufficiently increase the survival rate of cephalopods in an artificial rearing environment.
Claims
1. A method for cultivating cephalopods, comprising, when raising a school of cephalopods in an artificial rearing environment, rearing the school without allowing other schools different from the school to merge with the school during a predetermined period immediately after the hatching of the cephalopods, or, if the schools are merged, limiting the number of times of merger to three or less.
2. 2. The method for cultivating cephalopods according to claim 1, wherein the cephalopods are not allowed to merge with other shoals different from the shoal for a predetermined period of time immediately after hatching.
3. The method for cultivating cephalopods according to claim 1 , wherein the cephalopod school is a school containing cephalopod individuals that have been hatched together.
4. The method for cultivating cephalopods according to claim 1, wherein the cephalopods are raised while being flushed with seawater.
5. The method for cultivating cephalopods according to claim 4, wherein the temperature of the seawater is 10°C or higher and 30°C or lower.
6. The method for cultivating cephalopods according to any one of claims 1 to 5, wherein the total number of cephalopods is 200 or less over the specified period.