JP6986652B2 - Amberjack farmed fish breeding method and yellowtail farmed fish - Google Patents

Description

The present disclosure relates to a method for raising amberjack-cultured fish and amberjack-cultured fish.

Yellowtail is generally known as a fish that is in season in winter, and not only natural yellowtail but also cultured yellowtail is distributed from the viewpoint of maintenance of natural resources and quality control.
It is generally known that when yellowtail matures and reaches the spawning season, nutrients are taken up by eggs before and after that, resulting in thinning. For this reason, in the case of natural yellowtail, the spawning season of February to April or after that, and in the case of cultured yellowtail, the spawning season of May to June or after that, in many cases, growth stagnation occurs or fat paste occurs. It gets worse and the commercial value goes down. For this reason, various techniques for reducing the effects of growth stagnation, thinning, etc. on yellowtail farmed fish have been studied.

Patent Document 1 provides a aquaculture method in which there is no stagnation or decline in fish growth caused by reproductive organ maturation, spawning, and ejaculation organs, and the fish matures steadily without stagnation in shipment. Has been done. Specifically, a farming method for breeding yellowtail and the like while irradiating a lamp with a constant illuminance from the evening to the next morning for a period from October to May of the following year at the latest is disclosed. According to this method, it is stated that the growth of the reproductive organs of the fish is almost suppressed, spawning and sperm release into the water do not occur, and the fish continues to grow during this period.

Patent Document 2 describes a fish feed having a vitamin E content of 90 mg or less per kg and containing at least one antioxidant selected from the group consisting of coenzyme Q10, sesaminol, α-riboic acid and astaxanthin. It is stated that the use of this fish feed can suppress the stagnation of fish growth caused by reproductive activity.

Further, in Non-Patent Document 1, by restricting the intake of feed from winter to spring until just before the breeding season, the body weight is increased as compared with the non-restricted group, and the development of the gonads in the breeding season bristle. Is disclosed to be suppressed.

Japanese Unexamined Patent Publication No. 2003-333953 Japanese Unexamined Patent Publication No. 2013-188207

Aquaculture, 424-425 (2014) 10-17

However, the commercial value of yellowtail depends on the size, and when the weight is suppressed before the maturation period of the reproductive organ, or when the weight is greatly reduced after the maturation of the reproductive organ and the weight becomes about 3 kg. , It cannot be said that the commercial value is sufficient.
In addition, since the maturation of the reproductive organs is indispensable for the purpose of continuous cultivation while maintaining good traits as a farmed fish, the matured fish in which the maturation of the reproductive organs is completely suppressed is cultivated. Is lost in sustainability.

Therefore, an object of the present disclosure is to obtain a farmed fish of the genus Amberjack, which is hard to lose weight after the maturation period of the reproductive organ and has excellent sustainability.

The disclosure includes:
<1> In a controlled breeding environment, amberjack fish are bred for at least 2 months, and then breeding is started using larvae of amberjack fish obtained by artificially collecting eggs to grow yellowtail fish. matter,
Male individuals with a reproductive gland index (GSI) of 0.5% or more and 10.0% or less, or female individuals with a GSI of 0.5% or more and 4.5% or less at the maturity stage of the reproductive organs, and the degree of obesity Obtaining mature yellowtail farmed fish of 18 or more and weighing 3.5 kg or more,
From the obtained mature yellowtail aquaculture fish, after the reproductive organ maturation period, the obesity degree is 17 or more and the weight is 3.5 kg or more, and the reproductive gland index (GSI) is lower than the value at the reproductive organ maturation period. Amberjack farmed fish breeding method, including obtaining amberjack farmed fish.
<2> The breeding method according to <1> above, wherein the GSI of amberjack cultured fish after the reproductive organ maturity is 2.5% or less in male individuals and 1.0% or less in female individuals.
<3> The breeding method according to <1> or <2>, wherein the water temperature in the breeding environment of yellowtail fish is adjusted to 15 ° C. to 28 ° C. from the start of breeding of larvae of yellowtail fish.
<4> The above-mentioned <1> to <3>, which comprises removing individuals with abnormal morphology and / or poor growth during breeding in the above-mentioned growth and selecting individuals of the genus Amberjack. Breeding method.
<5> The breeding method according to any one of <1> to <4>, wherein the breeding in the above-mentioned breeding includes underwater aquaculture at 10 m to 18 m below the surface of the water for at least 5 months and is carried out for 15 months or more.
<6> The breeding method according to any one of <1> to <5>, wherein amberjack fish are quantitatively controlled during breeding in the breeding.
<7> The above-mentioned feeding including feeding a feed containing 0.1 parts by weight to 0.3 parts by weight of capsicum to 100 parts by weight of the feed to fish of the genus Amberjack during breeding in the above-mentioned growth for at least one month. The breeding method according to any one of <1> to <6>.
<8> At the maturity stage of the reproductive organs, the obesity degree is 18 or more and the body weight is 3.5 kg or more, and the reproductive gland index (GSI) is 0.5% or more and 10.0% or less in the case of males, and 0 in the case of females. It is 5.5% or more and 4.5% or less,
After the reproductive organ maturation period, the obesity degree is 17 or more and the body weight is 3.5 kg or more, and the reproductive gland index (GSI) is lower than the reproductive organ maturity period value.
Amberjack farmed fish.
<9> The yellowtail farmed fish according to <8> above, wherein the GSI of the yellowtail farmed fish after the reproductive organ maturation stage is 2.5% or less in male individuals and 1.0% or less in female individuals.
<10> Individuals in the mature stage of the reproductive organs, with an obesity degree of 18 or more and a body weight of 3.5 kg or more, and have a reproductive gland index (GSI) of 0.5% or more and 10.0% or less in males, and females. Amberjack farmed fish that is 0.5% or more and 4.5% or less in some cases.
<11> Individuals after the maturation stage of the reproductive organs, having an obesity degree of 17 or more and a body weight of 3.5 kg or more, and having a reproductive gland index (GSI) of less than 0.5% for males and 0. Amberjack farmed fish that is less than 5%.
<12> The yellowtail farmed fish according to <8> or <10> above, wherein the male amberjack farmed fish in the mature stage of the reproductive organ satisfies at least one of the following (1) to (3):
(1) The blood concentration of 11-ketotestosterone (11-KT) is 1800 pg / mL-4500 pg / mL,
(2) The blood concentrations of 17α, 20β-dihydroxy-4-pregnane-3-one (DHP) are 100 pg / mL to 450 pg / mL, and
(3) The blood concentration of estradiol (E2) is 130 pg / mL to 400 pg / mL.
<13> The yellowtail farmed fish according to <8> or <10> above, wherein the female amberjack farmed fish in the mature stage of the reproductive organ satisfies at least one of the following (4) to (6):
(4) The blood concentration of 11-ketotestosterone (11-KT) is 20 pg / mL to 175 pg / mL.
(5) The blood concentrations of 17α, 20β-dihydroxy-4-pregnane-3-one (DHP) are 100 pg / mL to 350 pg / mL, and
(6) The blood concentration of estradiol (E2) is 300 pg / mL to 10000 pg / mL.
<14> The yellowtail farmed fish according to any one of <8> to <13>, which has a fork length of 50 cm or more.
<15> The yellowtail farmed fish according to any one of <8> to <14>, which is yellowtail, amberjack, amberjack, or longfin yellowtail.
<16> Amberjack farmed fish obtained by the breeding method according to any one of <1> to <7>.
<17> In a controlled breeding environment, amberjacks are bred for at least 2 months, and then breeding is started using larvae of amberjacks obtained by artificially collecting eggs to grow amberjacks. matter,
Male individuals with a reproductive gland index (GSI) of 0.5% or more and 10.0% or less, or female individuals with a GSI of 0.5% or more and 4.5% or less at the maturity stage of the reproductive organs, and the degree of obesity Obtaining mature yellowtail farmed fish weighing 18 or more and weighing 3.5 kg or more,
How to raise mature yellowtail farmed fish, including.

According to the present disclosure, it is possible to obtain amberjack farmed fish that is hard to lose weight after the maturation period of the reproductive organ and has excellent sustainability.

The method for breeding amberjack cultured fish according to one aspect of the present disclosure uses larvae of amberjack fish obtained by artificially collecting eggs after breeding amberjack fish for at least two months in a controlled breeding environment. Start breeding and grow yellowtail fish, male individuals with a gonad index (GSI) of 0.5% or more and 10.0% or less, or GSI of 0.5% or more at the maturity stage of the reproductive organs. Obtain a mature yellowtail cultivated fish with an obesity degree of 18 or more and a weight of 3.5 kg or more in a female individual of 4.5% or less. It is a breeding method including obtaining a yellowtail farmed fish having an obesity degree of 17 or more and a weight of 3.5 kg or more and a gonad body index (GSI) lower than the value at the maturity stage of the reproductive organ.

The yellowtail farmed fish according to another aspect of the present disclosure is a yellowtail farmed fish obtained by the method for breeding amberjack farmed fish according to the above aspect.
Further, the breeding fish of the genus Buri according to another aspect of the present disclosure has an obesity degree of 18 or more and a body weight of 3.5 kg or more at the reproductive organ maturity stage, and the reproductive gland index (GSI) is 0.5 in the case of males. % Or more and 10.0% or less, 0.5% or more and 4.5% or less in the case of females, obesity degree of 17 or more and body weight of 3.5 kg or more after reproductive organ maturation, and reproductive gland index (GSI) is a genus Buri farmed fish whose reproductive organ maturity value is lower than the value.

According to the above-mentioned method for breeding amberjack-cultured fish in one aspect of the present disclosure, it is possible to obtain amberjack-cultured fish that is difficult to lose weight after the maturation period of the reproductive organ and has excellent sustainability.

To further explain this, in the method for breeding amberjack farmed fish of the present disclosure, amberjack fish are grown from larvae of amberjack fish obtained through artificial egg collection, and the weight is 3. A mature yellowtail farmed fish having a predetermined GSI of 5 kg or more and an obesity degree of 18 or more can be obtained. From such mature amberjack farmed fish with a body weight of 3.5 kg or more and an obesity degree of 18 or more and showing a predetermined GSI, although the GSI is lowered, the body weight of 3.5 kg or more is maintained and the obesity degree is 17 or more. Amberjack farmed fish can be obtained. Such amberjack farmed fish with a body weight of 3.5 kg or more and an obesity degree of 17 or more have sufficient commercial value even after the maturation period of the reproductive organs, and become a so-called "thin individual after the maturity period". Is not equivalent.
Therefore, according to the method for breeding amberjack-cultured fish disclosed in the present disclosure, even after the maturation period of the reproductive organs, the amberjack-cultured fish having a body weight of 3.5 kg or more and an obesity degree of 17 or more, which is not a “thin individual after the maturity period”. You can get fish.

The Buri cultivated fish according to one aspect of the present disclosure has a weight of 3.5 kg or more and obesity of 18 or more in the reproductive organ maturation stage even if the GSI is lower than the reproductive organ maturity stage after the reproductive organ maturity stage. It has a GSI in the range not too low, and has a weight of 3.5 kg or more and an obesity degree of 17 or more even after the reproductive organ maturity.
Therefore, it is possible to provide functional sperms or eggs during the reproductive organ maturation period, the culture is excellent in sustainability, and after the reproductive organ maturation period, the obesity is sufficiently high and the body weight is 3.5 kg or more. It also has the advantage of high commercial value because it is high and the proportion of edible parts is sufficiently high.

The yellowtail farmed fish according to another aspect of the present disclosure is an individual in the mature stage of the reproductive organ, has an obesity degree of 18 or more and a body weight of 3.5 kg or more, and has a reproductive gland index (GSI) of 0. It is a yellowtail farmed fish having 5% or more and 10.0% or less, and 0.5% or more and 4.5% or less in the case of females.
The reproductive organ matured yellowtail farmed fish according to another aspect of the present disclosure is an individual having a high degree of obesity and sufficient body weight, and having a GSI not too low as compared with natural yellowtail. The yellowtail farmed fish in the reproductive organ maturity stage can efficiently provide the yellowtail genus farmed fish after the reproductive organ maturity stage according to the above-described aspect.

The method for breeding amberjack cultured fish according to another aspect of the present disclosure is to breed yellowtail fish for at least two months in a controlled breeding environment, and then artificially collect eggs to obtain larvae of yellowtail fish. Obtaining, starting breeding from the obtained larvae of yellowtail fish and growing them into yellowtail fish, male individuals with GSI of 0.5% or more and 10.0% or less at the maturity stage of the reproductive organs, or GSI In the breeding method of mature yellowtail cultivated fish, including obtaining mature yellowtail cultivated fish having an obesity degree of 18 or more and a weight of 3.5 kg or more in a female individual of 0.5% or more and 4.5% or less. be.
According to the method for breeding amberjack farmed fish in the reproductive period according to this aspect, it is possible to provide the above-mentioned useful reproductive organ matured amberjack farmed fish.

In the present specification, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. ..
In the present specification, the numerical range indicated by using "~" shall indicate the range including the numerical values described before and after it as the minimum value and the maximum value, respectively.

In the present specification, the amount of each component in the mixture means the total amount of the plurality of substances present in the mixture when a plurality of substances corresponding to each component are present in the mixture, unless otherwise specified. .. In the present specification, the content of each component in the mixture is the total content of the plurality of substances present in the mixture when a plurality of substances corresponding to each component are present in the mixture, unless otherwise specified. means.
As used herein, the term "less than or equal to" or "less than" with respect to percentage includes 0%, ie, "not contained", unless otherwise stated, or includes values undetectable by current means. Means a range.
Hereinafter, the present disclosure will be described.

The breeding fish of the genus Buri according to one form of the present disclosure has an obesity degree of 18 or more and a body weight of 3.5 kg or more at the reproductive organ maturity stage, and has a reproductive gland index (GSI) of 0.5% or more in the case of males. 0.0% or less, 0.5% or more and 4.5% or less in the case of females, obesity degree of 17 or more and body weight of 3.5 kg or more after reproductive organ maturation, and reproductive gland index (GSI) However, it is a cultivated fish of the genus Buri, which is lower than the value at the maturity stage of the reproductive organs.

Amberjack (Seriola Cuvier), amberjack farmed fish, includes yellowtail (Seriola dumerili), hiramasa (Seriola lalandi Valenciennes), yellowtail (Seriola quinqueradiata), yellowtail (Seriola rivoliana Valenciennes), Seriola carpenteri, Seriola fa Gunther, Seriola peruana Steindachner, and Seriola zonata can be mentioned. The low GSI yellowtail farmed fish can be yellowtail, amberjack, amberjack, or longfin yellowtail, and can be yellowtail in particular.

The amberjack farmed fish may be a farmed fish obtained by any method, and is preferably obtained by breeding and managing with a feed containing a compound feed.
"Compound feed" means a feed in which materials are combined so as to satisfy nutrients such as proteins, vitamins and minerals necessary for the growth of fish. By "breeding management" is meant being bred with a diet selected to achieve a particular purpose.

The body weight (total body weight) of the aquaculture fish of the genus Amberjack according to the present disclosure is 3.5 kg or more in both the reproductive organ maturation stage and the reproductive organ maturation stage. The weight of amberjack farmed fish during the reproductive organ maturation period and after the reproductive organ maturation stage is preferably 3.8 kg or more, more preferably 4.0 kg or more, still more preferably 4.2 kg or more, still more preferably 4.5 kg or more. May be. In addition, there may be a change in body weight before and after the reproductive organ maturation stage of amberjack farmed fish, and such a change in body weight may be an increase or decrease in body weight before and after the reproductive organ maturity stage. .. In the case of weight loss, the weight loss range can be, for example, 0.5 kg or less, preferably 0.3 kg or less, or 0.2 kg or less.

As used herein, the term "reproductive organ maturity" refers to the period in which the reproductive organs are generally equipped with reproductive functions in Amberjack fish, and in the case of male individuals, fertilization and in the case of female individuals, spawning is possible. .. In the case of yellowtail, it generally corresponds to the age of 26 to 27 months after hatching, and usually corresponds to the period from April to May when the water temperature becomes 16 ° C to 19 ° C.
As used herein, the term "after reproductive organ maturity" means the period after reproductive organ maturation, after fertilization in the case of male individuals and after spawning in the case of female individuals. Later, or in the case of no fertilization or spawning, it means the period after the reproductive organ weight reaches the maximum in the reproductive organ maturation period and starts to decrease. In the case of yellowtail, it generally corresponds to the age of 28 months or later, and usually corresponds to the period from May to September when the water temperature is 20 ° C or higher.
In the present specification, "reproductive organ maturation stage" may be referred to simply as "maturity stage", and "post-reproductive organ maturity stage" may be simply referred to as "post-maturation stage".

As used herein, the term "male" refers to an individual that forms a testis, and refers to an individual having a ZZ type in a combination of chromosomes. As used herein, the term "female" refers to an individual that produces an ovary, and as a combination of chromosomes, an individual having a ZW type or a WW type.

The GSI in amberjack farmed fish is 0.5% or more and 10.0% or less for males and 0.5% or more and 4.5% or less for females at the maturity stage, and matures after the maturity stage. It will be lower than the GSI of the period.
Below, yellowtail farming with a weight of 3.5 kg or more and a GSI of 0.5% or more and 10.0% or less for males and 0.5% or more and 4.5% or less for females at maturity. Fish may be referred to as "low GSI yellowtail farmed fish".
The Gonad Somatic Index (GSI) as used herein is the ratio of gonad weight to visceral fish weight and is calculated based on the following formula:
GSI (%) = gonad weight (kg) / visceral weight (kg) x 100

When the low GSI yellowtail farmed fish is male, the GSI is 0.5% or more at the maturity stage, so it can be judged that the reproductive organs are sufficiently mature to produce functional sperm. On the other hand, since the GSI is 10.0% or less, it can be determined that the individual has a small degree of thinning due to the maturation of the reproductive organs after the maturation period.
The lower limit of GSI in the mature period is 0.7% or more, 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 4.0%. More than 5.0%, more than 6.0%, more than 7.0%, more than 7.2%, more than 7.5%, more than 7.7%, more than 8.0%, or more than 8.2% Can be. The upper limit of GSI in the mature stage can be 9.5% or less, 9.0% or less, or 8.8% or less.

When the low GSI yellowtail farmed fish is male, the reproductive organ includes the testis. The weight of the reproductive organ, that is, the testis, generally needs to be 100 g or more at the maturity stage, and can be 120 g or more, 150 g or more, 180 g or more, 200 g or more, 250 g or more, 300 g or more, or 350 g or more, and is the weight of the testis. The upper limit is not particularly limited, but may be 450 g or less, 430 g or less, or 400 g or less from the viewpoint of reducing the influence of thinning associated with the maturation of the reproductive organ.

When the low GSI yellowtail farmed fish is a female, the GSI is 0.5% or more at the maturity stage, so it can be judged that the reproductive organs are sufficiently mature to produce functional eggs. On the other hand, since the GSI is 4.5% or less, it can be judged that the individual is less affected by the thinning caused by the maturation of the reproductive organs after the maturation period.
The lower limit of GSI in the mature period is 0.7% or more, 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, or 3.5. It can be% or more. The upper limit of GSI in the mature stage can be 4.5% or less, 4.3% or less, 4.2% or less, or 4.0% or less.

When low GSI yellowtail farmed fish are female, the reproductive organs include ovaries. The weight of the reproductive organ, that is, the ovary, generally needs to be 20 g or more at the maturity stage, and can be 30 g or more, 40 g or more, 50 g or more, 80 g or more, 100 g or more, 120 g or more, or 140 g or more, and is the weight of the ovary. The upper limit is not particularly limited, but may be 300 g or less, 250 g or less, or 200 g or less from the viewpoint of reducing the influence of thinning associated with the maturation of the reproductive organ.

Since the GSI of the low GSI yellowtail farmed fish is within the predetermined range as described above, the concentration of various reproductive hormones at the maturity stage can be lower than that of the natural yellowtail fish. Examples of the reproductive hormone include 11-ketotestosterone (11-KT), 17α, 20β-dihydroxy-4-pregnane-3-one (DHP), estradiol (E2) and the like.

11-KT is one of the male sex hormones that functions as an endogenous androgen-like hormone, and is known as a hormone involved in the middle stage of the sperm maturation process. The blood concentration of 11-KT in mature low GSI yellowtail farmed fish is 1800 pg / mL or more, 2000 pg / mL or more, 2300 pg / mL or more, 2500 pg / mL or more, or 2700 pg / mL or more in the case of male individuals. It may be 3000 pg / mL or more, 4500 pg / mL or less, or 4300 pg / mL or less.

11-KT can also produce female individuals. The blood concentration of 11-KT in mature low GSI yellowtail farmed fish is 20 pg / mL or more, 25 pg / mL or more, 30 pg / mL or more, 50 pg / mL or more, or 100 pg / mL or more for female individuals. It may be 200 pg / mL or less, 180 pg / mL or less, or 160 pg / mL or less.

The method for measuring 11-KT in blood is not particularly limited, and any known measuring method may be used. For example, it can be measured by time resolved fluoroimmunoassay (TR-RIA). As the measurement method using TR-RIA, for example, the method described in Gen. Comp. Endocrinol. 106, 181-188 can be applied.

DHP, also referred to as 17α, 20β-dihydroxy-4-pregnane-3-one, is a luteinizing hormone that acts as an active testosterone and is known as a hormone involved in the late stages of sperm or egg maturation.
The blood concentration of DHP in mature low GSI yellowtail farmed fish is 100 pg / mL or more, 110 pg / mL or more, 130 pg / mL or more, 150 pg / mL or more, or 200 pg / mL or more in the case of male individuals. It may be 450 pg / mL or less, 400 pg / mL or less, or 350 pg / mL. In the case of female individuals, the blood concentration of DHP in low GSI yellowtail farmed fish may be 100 pg / mL or more, 120 pg / mL or more, 150 pg / mL or more, or 200 pg / mL or more, 350 pg / mL or less, It may be 320 pg / mL or less, or 300 pg / mL or less.
The method for measuring blood DHP is not particularly limited, and any known measuring method may be used. For example, it can be measured by time resolved fluoroimmunoassay (TR-FIA). As the measurement method using TR-FIA, for example, the method described in Gen. Comp. Endocrinol. 106, 181-188 can be applied.

E2 is one of the female sex hormones, also called 17-β-estradiol, and is known as a hormone that is directly or indirectly involved in the early stages of sperm or egg maturation. In the case of male individuals, the blood concentration of E2 in low GSI yellowtail farmed fish may be 130 pg / mL or more, 150 pg / mL or more, or 200 pg / mL or more, 400 pg / mL or less, 380 pg / mL or less, Alternatively, it may be 350 pg / mL or less. In the case of female individuals, the blood concentration of E2 in low GSI yellowtail farmed fish in the mature stage may be 300 pg / mL or more, 500 pg / mL or more, 800 pg / mL or more, or 1000 pg / mL or more, and 15000 pg / mL. It may be mL or less, 10,000 pg / mL or less, or 7,000 pg / mL or less.
The method for measuring blood E2 is not particularly limited, and any known measuring method may be used. For example, it can be measured by Radioimmunoassay (RIA). The measurement method using RIA is described in, for example, Cell Tissue Res., 218, 315-329.

The low GSI yellowtail farmed fish may have any of the above-mentioned reproductive hormones in the above range. For example, the mature low GSI yellowtail farmed fish may have the following combinations of reproductive hormones. can:
When the amberjack farmed fish is a male individual, at least one of the following (1) to (3):
(1) The blood concentration of 11-ketotestosterone (11-KT) is 1800 pg / mL-4500 pg / mL,
(2) The blood concentrations of 17α, 20β-dihydroxy-4-pregnane-3-one (DHP) are 100 pg / mL to 450 pg / mL, and
(3) The blood concentration of estradiol (E2) is 130 pg / mL to 400 pg / mL.
When the amberjack farmed fish is a female individual, at least one of the following (4) to (6):
(4) The blood concentration of 11-ketotestosterone (11-KT) is 20 pg / mL to 175 pg / mL.
(5) The blood concentrations of 17α, 20β-dihydroxy-4-pregnane-3-one (DHP) are 100 pg / mL to 350 pg / mL, and
(6) The blood concentration of estradiol (E2) is 300 pg / mL to 10000 pg / mL.

In the case of a male individual, at least one of the above (1) to (3) can be satisfied, for example, a combination of (1) and (2), a combination of (1) and (3), (2) and (3). ), And the combination of (1) to (3).
In the case of a female individual, at least one of the above (4) to (6) can be satisfied, for example, a combination of (4) and (5), a combination of (4) and (6), (5) and (6). ), And the combination of (4) to (6).

GSI in low GSI yellowtail farmed fish is within a predetermined range during maturity and decreases after maturity. The decrease in GSI before and after the maturity period is not particularly limited as long as the body weight is 3.5 kg or more and the obesity degree is 17 or more after the maturity period. % Or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less post-maturity GSI.

In low GSI Amberjack farmed fish, the GSI after maturity may be lower than the GSI value at maturity, that is, less than the GSI value at maturity, for example, less than the GSI value at maturity. It may be 2.5% or less in the case of males and 1.0% or less in the case of females. In other words, post-maturity aquaculture fish of the genus Amberjack have an obesity degree of 17 or more and a body weight of 3.5 kg, and the GSI is lower than that of the mature GSI, which is 2.5% or less in the case of males. In the case of females, it may be 1.0% or less.
The GSI after maturity of male individuals is less than the GSI value of maturity, and in the case of male individuals, 2.5% or less, 2.0% or less, 1.8% or less, 1.5% or less, It may be 1.3% or less, 1.0% or less, 0.8% or less, 0.5% or less, or 0.3% or less. The post-maturity GSI of female individuals is lower than the mature GSI, 2.0% or less, 1.5% or less, 1.0% or less, 0.9% or less, 0.8%. Below, it may be 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, or 0.1% or less.

The obesity of low GSI yellowtail farmed fish is 18 or more at the maturity stage, preferably 19 or more, more preferably 20 or more, and even more preferably 21 or more. The upper limit of the degree of obesity in the maturity period is not particularly limited as long as the degree of obesity after the maturity period is 17 or more, and may be, for example, 30 or less or 29 or less.
Further, the obesity degree of the low GSI yellowtail farmed fish is 17 or more after the maturity period, and can have an obesity degree of preferably 18 or more, more preferably 19 or more. Low GSI yellowtail farmed fish with an obesity degree of 17 or higher after maturity can provide more so-called greasy edible parts as compared to natural fish. The upper limit of the degree of obesity after maturity is not particularly limited and may be, for example, 29 or less or 28 or less.

The degree of obesity can generally be evaluated based on the following formula [1].
Classification of obesity =
Weight (g) / {Caudal ramus length (cm) x Caudal ramus length (cm) x Caudal ramus length (cm)} x 1000 ... [1]

The low GSI Amberjack farmed fish of the present disclosure maintain a body weight of 3.5 kg or more at the maturity stage and thereafter, and the degree of obesity is after the maturity stage even if the obesity level is lower than the obesity level at the maturity stage. It is maintained above 17. The range of variation in the degree of obesity between maturity and post-maturity in low GSI Amberjack farmed fish is not particularly limited as long as the degree of obesity is 17 or more after maturity, but is preferably 2 or less, more preferably 1 or less. Can be.

The tail fork length of low GSI yellowtail farmed fish can have a tail fork length of 50 cm or more, 55 cm or more, 57 cm or more, or 60 cm or more for both males and females. Amberjack farmed fish having a tail fork length of 50 cm or more has a strong tendency to have a higher degree of obesity than natural fish, and can provide more edible portions. Caudal ramus length refers to the distance from the tip of the head of the fish to the end of the center of the tail fin, and is an index of external morphology well known to those skilled in the art. The length of the caudal ramus is measured by measuring the distance in a straight line in a plane from the tip of the head of the fish to the end of the center of the tail fin. The upper limit of the tail fork length of low GSI yellowtail farmed fish is not particularly limited and may be, for example, 200 cm or less.

To measure the weight of an individual fish, the weight of the fish body obtained by first draining blood after landing is measured and used as the "total fish weight". After that, the internal organs can be removed and the gonad weight and the liver weight can be measured respectively. For the measurement of the weight, a measuring instrument usually used for measuring the weight of the fish and a measuring instrument usually used for measuring the weight of the internal organs can be used.

The low GSI Amberjack farmed fish in one aspect of the present disclosure can have the following characteristics during reproductive organ maturity:
(A1-1) A male individual having a body weight of 3.5 kg or more, an obesity degree of 20 or more, and a GSI of 2.5% or more and 10.0% or less.
(A1-2) A male individual having a body weight of 4.0 kg or more, an obesity degree of 20 or more, and a GSI of 5.0% or more and 9.0% or less.
(B1-1) A female individual having a body weight of 3.5 kg or more, an obesity degree of 19 or more, and a GSI of 1.0% or more and 4.5% or less.
(B1-2) A female individual having a body weight of 4.0 kg or more, an obesity degree of 19 or more, and a GSI of 2.0% or more and 4.0% or less.

The low GSI Amberjack farmed fish in one aspect of the present disclosure may have the following characteristics:
(A2-1) Weight is 3.5 kg or more, obesity is 20 or more, GSI at maturity is 2.5% or more and 10.0% or less, and GSI after maturity is 2.5. % Of male individuals,
(A2-2) Weight is 4.0 kg or more, obesity is 20 or more, GSI at maturity is 5.0% or more and 9.0% or less, and GSI after maturity is 5.0. % Of male individuals,
(B2-1) Weight is 3.5 kg or more, obesity is 19 or more, GSI at maturity is 1.0% or more and 4.5% or less, and GSI after maturity is 1.0. % Of male individuals,
(B2-2) Weight is 4.0 kg or more, obesity is 19 or more, GSI at maturity is 2.0% or more and 4.0% or less, and GSI after maturity is 2.0. A male individual that is less than%.

The low GSI yellowtail farmed fish of the present disclosure has the above-mentioned body weight and obesity, and has a lower GSI than natural yellowtail. Low GSI Amberjack farmed fish with such characteristics can be at least 1.2 years old or older, or 1.5 years old or older, generally 2 years old or 3 years old or older. In particular, like natural yellowtail, it may be not only a farmed fish for spring egg collection but also a farmed fish for autumn egg collection. Yellowtail farmed fish for autumn egg collection can be obtained by shifting the timing of collecting eggs or sperm from the parent fish by artificially controlling conditions such as light irradiation and water temperature, and applying the administration of mature hormone. can.

The other aquaculture fish of the genus Amberjack of the present disclosure are individuals in the mature stage of the reproductive organs, and have a body weight of 3.5 kg or more, an obesity degree of 18 or more, and a GSI of 0.5% or more in the case of males. It is a yellowtail farmed fish of 0% or less, and 0.5% or more and 4.5% or less in the case of females. When this yellowtail farmed fish is particularly referred to, it may be referred to as "mature low GSI yellowtail farmed fish" in the present specification. The mature low GSI yellowtail farmed fish may have the above-mentioned characteristics (A1-1) to (A1-2) or (B1-1) to (B1-2).
Mature low GSI yellowtail farmed fish is preferable in order to efficiently obtain post-maturity low GSI yellowtail farmed fish.

The other Amberjack farmed fish of the present disclosure are individuals after reproductive organ maturation, weighing 3.5 kg or more and obesity of 17 or more, and have a GSI lower than the GSI value at maturity. It is a genus farmed fish. This yellowtail farmed fish may be referred to herein as "post-maturity low GSI yellowtail farmed fish". Post-maturity low GSI yellowtail farmed fish, for example, weigh 3.5 kg or more and obesity of 17 or more, and GSI is less than 2.5% for males and 1.0% for females. Less than amberjack farmed fish, or amberjack farmed fish weighing 3.5 kg or more and obesity of 17 or more, with a GSI of less than 0.5% for males and less than 0.5% for females It can be a fish.

The mature low GSI yellowtail farmed fish and the post-mature low GSI yellowtail farmed fish are the same as the above-mentioned matters concerning the weight, GSI, reproductive hormone, obesity degree, tail fork length, etc. regarding the low GSI yellowtail farmed fish of the present disclosure. Can be applied.

The low GSI yellowtail farmed fish according to the present disclosure adjusts the GSI within a predetermined range by controlling or adjusting the composition, day length condition, water temperature condition, farming period, feeding amount, weight, etc. of the compound feed used for farming. Can be obtained by doing. Examples of the method capable of adjusting the maturation of the gonads include the methods described in JP-A-2013-188207, JP-A-2013-188207, and JP-A-2015-510878. Among them, the introduction of foreign substances can be applied by applying a method for adjusting the maturation of the gonads based on the composition of the compound feed that can adjust the maturation of the gonads, the day length condition that can adjust the maturation of the gonads, and the water temperature condition. It is preferable in that there are few points.
The amberjack farmed fish according to the present disclosure can be obtained by the method for breeding amberjack farmed fish described in the present specification.

<How to raise amberjack farmed fish>
The method for breeding low GSI Amberjack cultivated fish according to the present disclosure is to use larvae of Amberjack fish obtained by artificially collecting eggs after breeding Amberjack fish for at least 2 months in a controlled breeding environment. Start breeding and grow yellowtail fish (hereinafter referred to as "breeding process"), male individuals with GSI of 0.5% or more and 10.0% or less during reproductive organ maturity, or To obtain a mature yellowtail farmed fish with a GSI of 0.5% or more and 4.5% or less, an obesity degree of 18 or more and a weight of 3.5 kg or more (hereinafter referred to as "mature stage individual acquisition step"). From the obtained mature Amberjack cultured fish, after the reproductive organ maturation stage, the obesity degree is 17 or more and the weight is 3.5 kg or more, and the GSI is lower than the value at the reproductive organ maturation stage. It includes obtaining amberjack-cultured fish (hereinafter, may be referred to as “post-maturity individual acquisition step”), and includes other steps as necessary.
In this breeding method, according to the method of breeding amberjack-cultured fish, it is possible to obtain amberjack-cultured fish that is hard to lose weight after the maturation period of the reproductive organ and has excellent sustainability.
The term "breeding method" can be regarded as a method for producing low GSI yellowtail farmed fish disclosed in the present disclosure, and should be used interchangeably with any of the terms such as "production method" and "production method". Can be done.
In addition, "controlled breeding" refers to breeding while appropriately adjusting the day length condition and the water temperature condition.

[Breeding process]
In the breeding process, larvae of yellowtail fish obtained by artificially collecting eggs after breeding yellowtail fish for at least 2 months in a controlled breeding environment are used.
As the above-mentioned larvae, those obtained by purchasing larvae of Amberjack genus fish obtained by artificially collecting eggs from Amberjack genus fish bred in a controlled breeding environment for 2 months may be used. , The person who performs the above-mentioned breeding step may use the one obtained by breeding in the above-mentioned controlled breeding environment for at least two months and at least one selected from the group consisting of the above-mentioned egg collection.
Further, the collected eggs are subjected to the fertilization process after the egg collection in order to obtain larvae, but the person who performs the above-mentioned breeding step may perform the above-mentioned fertilization process, and the person who performs the above-mentioned breeding process may perform the above-mentioned fertilization process. The larvae obtained later may be obtained by means such as purchase and used for growth in the breeding process.
The day length condition in controlled breeding means that a light period of 9 hours to 15 hours and a dark period of 9 hours to 15 hours are appropriately combined. For example, under the short-day condition, the light period of 10 hours and the dark period of 14 hours can be performed for 30 days, and under the long-day condition, the light period of 14 hours and the dark period of 10 hours can be performed for 60 days. The water temperature condition means adjusting the water temperature within the range of 15 ° C to 30 ° C or 16 ° C to 28 ° C.
The day length condition and the water temperature condition in the controlled breeding can be appropriately adjusted according to the breeding. For example, if a preferable light-dark cycle or water temperature can be achieved in a natural environment, the conditions may be applied as they are.

Breeding in a controlled breeding environment can be carried out for at least 2 months, preferably 3 months or longer, more preferably 7 months or longer. By adjusting the day length condition and the water temperature condition, for example, the maturation of the reproductive organs of a female individual can be promoted, which enables egg collection at least 3 months earlier than that of natural yellowtail.

Eggs are collected artificially. Here, "artificial" means to induce egg laying in an environment controlled from the outside such as adjustment of the environment and administration of a drug at the time of egg collection. As a result, for example, eggs can be collected faster than natural yellowtail. In Japan, eggs may be collected at any time of the year.
The collected eggs are then subjected to fertilization. By holding the fertilized egg after fertilization under a predetermined environment, larvae of yellowtail fish can be obtained. The larvae of yellowtail fish are used for growth.

In the breeding process, breeding is started using larvae of yellowtail fish to grow yellowtail fish. In order to start breeding from larvae of yellowtail fish and grow yellowtail fish, larvae to adult fish of yellowtail fish may be bred by a method usually performed in an environment suitable for the growth stage. Amberjack fish that have reached a size suitable for sea surface aquaculture can be bred on the sea surface. Amberjack fish should generally be bred in an environment where yellowtail grows.
In the present specification, the "larva of yellowtail fish" means an individual whose tail fork length is smaller than about 5 cm after hatching, and the fry and adult fish after that are collectively referred to as "amberjack fish".

The water temperature under the breeding environment of yellowtail fish is preferably adjusted to 15 ° C. to 28 ° C. from the viewpoint of the growth efficiency of yellowtail fish. At this time, by adjusting the water temperature under the breeding environment within the range of 15 ° C to 28 ° C from the start of breeding of yellowtail larvae, the stage of breeding yellowtail fish is higher than that of starting from a later stage. From the early stage, the growth rate of yellowtail fish can be accelerated to efficiently obtain low GSI yellowtail farmed fish.
The adjustment of the water temperature in the breeding process can be changed according to the breeding stage. For example, for the breeding of larvae of yellowtail fish, the temperature can be adjusted to 18 ° C. to 22 ° C., and after the larvae grow to become yellowtail fish, the temperature can be adjusted to 15 ° C. to 28 ° C. Examples of water temperature adjustment include water addition, heating, adjustment of ambient temperature, shading, adjustment of sunshine duration, selection of sea surface farm, transfer of breeding fish, and the like.
The breeding process may include a period of high water temperature exceeding 28 ° C. For example, letting amberjack fish in the process of maturation experience a high water temperature of 30 ° C. or higher may be effective in adjusting maturity by applying an appropriate stress to an individual. The water temperature that becomes the "high water temperature" in the breeding step can be, for example, 29 ° C, 30 ° C, or 31 ° C. The period of high water temperature can be 1 day or more, 2 days or more, 3 days or more, or 5 days or more. The period of high water temperature may be continuous or intermittent.

In the breeding process, in order to obtain the target amberjack cultivated fish more effectively, the individuals with morphological abnormalities and / or poor growth are removed during the breeding in the above-mentioned breeding, and the individuals of the genus Amberjack are selected. May include. Morphological abnormalities and / or poor growth can be determined based on feeding efficiency, feeding rate, body weight, body length, caudal ramus length, and the like. The body weight, body length, caudal ramus length, etc. may be collectively referred to as "size" in the present specification. Examples of the morphological abnormality include head depression, spinal curvature, short body, and jaw abnormality. The selection rate due to morphological abnormality or poor growth can be evaluated by the following formula.
Selection rate (%) = normal fish population / (morphologically abnormal or stunted population + normal fish population) x 100

In the breeding process, individual weighing control can be performed. Individual weighing control may be performed in combination with individual selection based on morphological abnormalities and / or poor growth. Weighing control means that the size of amberjack farmed fish is measured or estimated on a regular basis and controlled. The measurement management method is not particularly limited, and examples thereof include body weight measurement and image analysis. For example, the weight of an individual can be measured and measured every month. In this case, the weight of each individual, that is, the body weight may be measured, or several tens of animals may be measured together, the average may be calculated, and the average value may be used for management. Further, as the image analysis means, for example, "AM-100" (AQ1 systems) can be used. As the body weight measuring means, for example, "AM-100" (AQ1 systems) can be used.

The breeding period of yellowtail fish in the breeding process can be continued until a mature individual having a body weight of 3.5 kg or more is obtained, and may be 12 months or longer, 15 months or longer, 18 months or longer, 20 months or longer. It can be more than a month or more than 22 months. The breeding process can be continued until the post-maturity individual acquisition process described later.

The breeding in the breeding process may be carried out in the ocean or on land. From the viewpoint of ease of individual management and acquisition efficiency of low GSI yellowtail farmed fish, it is preferable to include underwater aquaculture at 10 m to 18 m below the surface of the water for at least 5 months. Such underwater aquaculture is also called a subsidence type, and it is easy to provide a breeding environment that is excellent in water temperature stability and is not easily affected by waves and the like. Underwater aquaculture can be carried out for at least 5 months, at least 6 months, or at least 8 months. The upper limit of the underwater aquaculture period is not particularly limited and can be appropriately set according to the breeding period.

The water temperature of 10 m to 18 m below the surface of the water where underwater aquaculture is carried out is often constant in the range of 15 ° C to 28 ° C, which is preferable from the viewpoint of environmental stability. However, the position below the surface of the water where underwater aquaculture is carried out may be a position shallower than 10 m or a position deeper than 18 m. At the time of feeding, the position of underwater aquaculture can be raised from the sea to the surface of the sea. In addition, the shallower the position, the higher the water temperature, and the deeper the position, the lower the water temperature. Taking advantage of this, the water temperature can be adjusted depending on the position where sea surface aquaculture is performed. In addition, the above-mentioned breeding at a high water temperature may be applied to aquaculture in the sea. In this case, for example, by moving the breeding position closer to the sea surface where the water temperature tends to be higher, a breeding environment with a high water temperature can be easily provided and maturation adjustment can be performed more efficiently.
In the present disclosure, the case where the upper limit of the cage used for aquaculture is above the sea level is referred to as sea surface culture, and the case where the upper limit of the cage is below the sea surface is referred to as undersea aquaculture.

The feed used in the breeding process is not particularly limited, and the feed normally used for amberjack farmed fish can be used without limitation. As the feed for aquaculture fish of the genus Amberjack, a feed containing 0.1 parts by weight to 0.3 parts by weight of capsicum can be used with respect to 100 parts by weight of the feed. Hereinafter, this feed is referred to as "capsicum-containing feed". Pepper is known to have an effect of improving or retaining blood tone in amberjack farmed fish (for example, Japanese Patent Application Laid-Open No. 2009-232864), and is also effective for obtaining a low GSI yellowtail farmed fish. The capsicum in the capsicum-containing feed can be a capsicum component or a capsicum powder.

The capsicum-containing feed may contain clove oil in addition to the capsicum. The blending amount of clove oil can be 0.1 part by weight to 0.25 part by weight with respect to 100 parts by weight of the feed.
The period of feeding with the capsicum-containing feed is not particularly limited, and for example, it can be fed for at least 1 month, at least 2 months, or at least 3 months.

Feeding of yellowtail fish in the breeding process is preferably performed without limitation during the breeding period from the viewpoint of efficiently obtaining low GSI yellowtail farmed fish. That is, in the breeding step, it is preferable to perform satiety feeding without limiting the amount and composition of the feed. Satiety feeding refers to feeding until no individual requesting food is observed on the surface of the water. From the viewpoint of more efficiently obtaining low GSI yellowtail farmed fish, highly satiety feeding is preferable. Highly satiety feeding refers to feeding until no feeding can be seen while observing with an underwater camera. This makes it possible to achieve satiety in more individuals, preferably all in captivity, taking into account the feeding behavior in water that cannot be confirmed on the surface of the water. By performing highly satiety feeding, the growth rate of yellowtail fish in the breeding process is high, and it is possible to more reliably obtain a mature low GSI yellowtail farmed fish.

In the breeding step, it is preferable to remove at least one of the stunted individuals selected from the group consisting of morphological abnormalities and stunted growth. By removing the individual having such a stunted growth, it is possible to select an individual having a better growing state than the growing state of the gonads, and to obtain a low GSI yellowtail farmed fish more efficiently. An individual having a morphological abnormality is an individual in which head depression, spinal curvature, short body, jaw abnormality, etc. are observed, and an individual whose appearance can be clearly confirmed by observation. An individual having poor growth is an individual that can be clearly confirmed to be inferior to the growth state at the same time by observation. Since morphologically abnormal individuals have limited growth, they are likely to cause poor growth from the viewpoint of total weight. If the morphological abnormality does not stop the growth of the gonads, the morphologically abnormal individual can be eliminated to eliminate the poorly grown individual having a high GSI.

[Mature individual acquisition process]
In the maturity individual acquisition step, a male individual having a GSI of 0.5% or more and 10.0% or less, or a female individual having a GSI of 0.5% or more and 4.5% or less at the reproductive organ maturity stage. A mature yellowtail farmed fish with an obesity degree of 18 or more and a weight of 3.5 kg or more can be obtained.
The mature Amberjack farmed fish obtained here is a mature individual having a body weight of 3.5 kg or more and an obesity degree of 18 or more, and has a lower GSI than the natural or other farmed fish of the mature individual. By obtaining such a mature yellowtail farmed fish, it is possible to obtain a post-maturity low GSI yellowtail farmed fish in the subsequent post-maturity individual acquisition step.
In the maturity individual acquisition step, individuals having the desired GSI, body weight and obesity can be selected by measuring the size, measuring the blood hormone concentration, and the like. The methods described above for weighing control can be applied to the measurement of size. Examples of blood hormones include 11-KT, DHP, E2 and the like. For the measurements of 11-KT, DHP and E2, the methods described above can be applied.

The degree of obesity of mature Amberjack farmed fish is relatively high, and may be preferably 19 or more, 20 or more, or 21 or more. The upper limit of the degree of obesity in mature yellowtail farmed fish is not particularly limited, and the above-mentioned items can be applied as they are to mature yellowtail farmed fish, which can be, for example, 28 or less or 27 or less.
Amberjack farmed fish in the mature stage can be obtained by a breeding method including the step of acquiring the individual in the mature stage. Since the reproductive organs of the mature Amberjack cultured fish obtained here are sufficiently mature, eggs or sperms can be obtained from this individual. The eggs or sperms from the mature Amberjack cultivated fish obtained here can be used as seedlings for obtaining Amberjack larvae having useful traits. That is, it can be said that the method for raising yellowtail-cultured fish according to the present disclosure is excellent in the sustainability of aquaculture. Further, the matured yellowtail farmed fish may be supplied to the next post-maturity individual acquisition step.

[Individual acquisition process after maturity]
In the post-maturity individual acquisition process, from the obtained mature amberjack farmed fish, the obesity degree is 17 or more and the weight is 3.5 kg or more, and the GSI is lower than the value at the reproductive organ maturity stage. That is, amberjack farmed fish is obtained after the maturity period. As for the post-maturity yellowtail farmed fish, the above-mentioned matters regarding the post-maturity low GSI yellowtail farmed fish can be applied as they are.
The obtained post-maturity amberjack farmed fish is a yellowtail farmed fish that has been prevented from losing weight to less than 3.5 kg or an obesity degree of less than 17, and such useful traits can be continued to the next generation. can.
Individuals with the desired GSI, body weight and obesity can be selected based on values such as size, blood hormone concentration, etc., similar to mature Amberjack farmed fish, or landed and weighed the reproductive organs. You can also select by doing.

[Use]
Further, by using the method for breeding amberjack-cultured fish according to the present disclosure, it is possible to adjust the provision time of the amberjack-cultured fish having good traits. The post-maturity amberjack farmed fish according to the present disclosure can be provided at an appropriate time depending on the condition of the farmed fish, for example, within 6 months, 4 months, 3 months, or 2 months from the maturity. Can be provided within. For example, if a 3-year-old mature yellowtail farmed fish is obtained from April to May, the post-mature yellowtail farmed fish can be provided from May to September. This makes it possible to stably provide, for example, amberjack farmed fish showing a good degree of obesity and body weight before summer when red tide is likely to occur.

The low GSI yellowtail farmed fish of the present disclosure has sufficient body weight and obesity, and therefore has high nutritional value as a farmed fish. Therefore, the low GSI yellowtail farmed fish of the present disclosure has a large proportion of high-quality edible parts as compared with the natural yellowtail, and thus the obesity degree of less than 17, and the yellowtail farmed fish having a high GSI. be able to.
The edible portion of amberjack farmed fish is preferably used as processed foods, for example, the following heated foods and non-heated foods, and can also be applied as animal feeds. The processed food and animal feed according to one embodiment may contain an edible portion of low GSI Amberjack farmed fish.

Examples of animal feeds include cat foods, dog foods, farmed fish feeds, poultry feeds, and livestock feeds. The ratio of the edible portion of the low GSI yellowtail farmed fish in the animal feed is not particularly limited and may be 0.1% by weight to 100% by weight or the like. In addition to the edible portion of low GSI yellowtail farmed fish, animal feeds include other nutrients such as vitamins, carriers and excipients that are acceptable as animal feeds such as water, depending on the type of animal to be targeted. Other additives such as, etc. can be appropriately included as needed. The animal feed may be contained in a container described later. Examples of the food include non-heated foods and heated foods.

One embodiment of the present disclosure comprises an edible portion of a low GSI yellowtail farmed fish and a processed food of a low GSI yellowtail farmed fish containing a container for accommodating the edible portion. The processed food may include a heated product and a non-heated product.
The non-heated product means an edible portion that has not been cooked, and includes surimi, sashimi, sashimi, blocks and fillets, as well as these frozen products, chilled products, freeze-dried products, dried fish, and pickles. be able to. It can be judged from the color tone of the surface of the edible portion that it is not cooked. As used herein, the term "heating" means that heat is applied to a state in which actomyosin is denatured to a visible extent. When the edible portion of the farmed fish is heat-treated, the edible portion is discolored due to the denaturation of actomyosin, so that the judgment can be made based on the discoloration of the edible portion.
The heated product means an edible portion that has been cooked, and examples thereof include simmered foods, grilled foods, steamed foods, fried foods, and paste products.

The shape of the edible portion contained in the processed food is not particularly limited, and may have a shape peculiar to the portion of the edible portion, or may be an amorphous shape obtained by shredding, and further specified. It may be molded in the shape of.

The processed food may optionally include at least one selected from the group consisting of other foods, food materials and accessories. Other foods include rice, radish (radish, seaweed, etc.), ginger (gari), sprout, and the like. Examples of the food material include green onions and green onions for roasting. Examples of accessories include baluns, labels, ice packs, coolants, ice, dry ice, sherbet ice and the like. The accessory may be housed in the container together with the edible portion, may be arranged on the outside of the container, may be inseparable from the container, or may be detachably attached. .. Other foods, food materials and accessories may be one or more combinations, respectively.

The container may be any container used to accommodate the edible portion, and examples thereof include styrofoam, paper, vinyl, soft plastic, hard plastic, metal, and glass. The shape of the container may be any shape as long as it can accommodate an edible portion, and examples thereof include a packaging sheet, a tray with or without a lid, a bag, a can, and a bottle.

The low GSI yellowtail farmed fish of the present disclosure can be crossed with other low GSI yellowtail farmed fish or amberjack farmed fish having other traits. From this, offspring having the genetic traits of low GSI Amberjack cultured fish can be obtained and used as seedlings for aquaculture.

Hereinafter, the present disclosure will be described in detail with reference to Examples. However, the present invention is not limited thereto. Unless otherwise specified, "part" or "%" is based on mass.

[Example 1]
The yellowtail larvae were bred in a natural environment for 24 months, and then from the 29th month, the breeding was started by adjusting the day length conditions and the water temperature. The feeding was usually satiety feeding once a day and once every two days in winter. As the day length condition, the short day condition and the long day condition were adopted. In addition, the breeding conditions were adjusted according to the conditions described in Japanese Patent Application Laid-Open No. 2007-300837.

Eggs were collected from female individuals by injecting hormones to induce egg laying. Sperm were collected from male individuals and fertilized to obtain yellowtail larvae. The larvae were bred on land at a water temperature of 18 ° C to 20 ° C. From the 3rd month when they were raised as fry, they were bred in cages installed on the surface of the sea. The above-mentioned fry were subsided 10 m to 18 m below the surface of the water, and underwater aquaculture was started. During the fry period, the water temperature was adjusted to 15 ° C to 22 ° C. The water temperature is adjusted to 15 ° C to 28 ° C during the adult fish season, and during the breeding period, the body weight of the growing individual is about 500 g to 1 kg, and the temperature reaches at least 30 ° C for 2 consecutive days. It was set for more than a day to allow growing individuals to experience high water temperatures.

The feeding was usually once a day with high satiety and once every two days in winter, with high satiety throughout the year, and no feeding restrictions were applied. However, the highly satiety feeding at this time is not based on the normal highly satiety feeding by observing the water surface, but based on the optimum highly satiety feeding method obtained by observing the feeding behavior in water with a camera. During the sea surface aquaculture period, fry or adult fish subsided 10 to 18 m below the surface of the water were raised to the surface of the sea each time they were fed. As the feed, a commercially available EP (extruded pellet) to which 0.1 part by weight to 0.3 part by weight of capsicum powder was added to 100 parts by weight of the feed was used.
When the fry weighed 2 g to 20 g, they were picked up from the land tank and moved to the sea surface cage. The above operation is also called "offshore". After going offshore during the breeding period, the body length, size, morphology, etc. were confirmed at any time, and the body weight was measured every other month. For the body weight measurement, a body weight measurement method using AM-100 (AQ1 system) was adopted. Based on these results, only individuals with no morphological abnormalities (head depression, spinal curvature, short body, jaw abnormalities) and which seemed to have a good growth rate were bred. The selection rate for morphological abnormalities was 50 to 95%.

During the reproductive organ maturation period, which is more than 5 months after the start of underwater cultivation, a male with an average weight of 4.63 kg, an average fork length of 61.03 cm, and an average obesity of 20.35, and an average weight of 4.66 kg, average. Two-year-old female fish with a fork length of 61.60 cm and an average obesity of 19.91 were obtained. The gonad weights of these 2-year-old fish were measured, the GSI was calculated, and the blood hormone concentration was measured as follows.

Blood was drawn from the heart of the fish, and after centrifugation, the supernatant was collected and stored at -80 ° C until analysis. When drawing blood, a syringe treated with sodium heparin (concentration: 5,000 units / mL, Wako Pure Chemical Industries, Ltd.) was used.
The amount of 11-KT was measured using Testosterone, 11-Keto-, EIA Kit (Strip Plate) (Cayman Chemicals). For the amount of DHP, use the Maturation-Inducing Steroid (salmonid) AChE Tracer, Maturation-Inducing Steroid (salmonid) EIA Antiserum, Precoated (Mouse Anti-Rabbit IgG) EIA 96well Strip Plate, Gen. Comp. Endocrinol. 106 , 181-188, measured by Time Resolved Fluoroimmunoassay (TR-FIA). The amount of E2 was measured using Estradiol, EIA Kit (Strip Plate) (Cayman Chemicals).
The results are shown in Table 1.

As shown in Table 1, it was possible to obtain mature yellowtail farmed fish having a body weight of 3.5 kg or more and an obesity degree of 18 or more while having a low GSI.

These mature yellowtail farmed fish were able to lay eggs or ejaculate. When the obtained yellowtail farmed fish were crossed with individuals having low GSI, the next generation of yellowtail larvae could be obtained. That is, it can be said that the aquaculture fish of the genus Amberjack obtained in this example is excellent in the sustainability of aquaculture.
The obtained mature yellowtail farmed fish had a body weight of 3.5 kg or more and an obesity degree of 17 or more in June, two months after the maturity period, and had a GSI of less than 0.5 for both male and female individuals. I was able to confirm that.

[Example 2]
In the same manner as in Example 1, larvae obtained by early egg collection were bred, and a mature yellowtail-cultured fish as a female individual of a 2-year-old fish and a post-maturation period as a female individual in April 74 days after the maturity period. Obtained yellowtail farmed fish. For these mature yellowtail cultured fish and post-mature yellowtail cultured fish, the body weight, the degree of obesity, and the GSI were measured in the same manner as in Example 1. The results are shown in Table 2.
As shown in Table 2, the individual had a body weight of 3.5 kg or more and an obesity degree of 17 or more even after the maturity period.

This yellowtail farmed fish has a high proportion of edible parts because its GSI is sufficiently low, and has a high degree of obesity, so its commercial value is high, and it was delicious when eaten.

As described above, according to the present disclosure, it is possible to obtain a yellowtail farmed fish that is hard to lose weight after the maturation period of the reproductive organ and has excellent sustainability.

Claims (13)

Amberjack fish should be bred for at least 2 months in a controlled breeding environment, and then breeding should be started using larvae of yellowtail fish obtained by artificially collecting eggs to grow yellowtail fish.
Male individuals of 2-year-old fish with a reproductive gland index (GSI) of 0.5% or more and 10.0% or less at the maturity stage of the reproductive organs, and a mature yellowtail farmed fish with an obesity degree of 18 or more and a body weight of 3.5 kg or more. To get,
From the obtained mature yellowtail aquaculture fish, after the reproductive organ maturation period, the obesity degree is 17 or more and the weight is 3.5 kg or more, and the reproductive gland index (GSI) is lower than the value at the reproductive organ maturation period. Amberjack farmed fish breeding method, including obtaining amberjack farmed fish. The breeding method according to claim 1, wherein the GSI of the aquaculture fish of the genus Amberjack after the reproductive organ maturity is 2.5% or less. The breeding method according to claim 1 or 2, wherein the water temperature in the breeding environment of the yellowtail fish is adjusted to 15 ° C. to 28 ° C. from the start of breeding the larvae of the yellowtail fish. The breeding method according to any one of claims 1 to 3, comprising removing individuals with abnormal morphology and / or poor growth during breeding in the above-mentioned breeding and selecting individuals of the genus Amberjack. The breeding method according to any one of claims 1 to 4, wherein the breeding in the above-mentioned breeding includes underwater aquaculture at 10 m to 18 m below the surface of the water for at least 5 months and is carried out for 15 months or more. The breeding method according to any one of claims 1 to 5, wherein measurement control of yellowtail fish is performed during breeding in the breeding. Claims 1 to include feeding amberjack fish with a feed containing 0.1 parts by weight to 0.3 parts by weight of a yellowtail for at least 1 month during the breeding in the above-mentioned breeding. The breeding method according to any one of claims 6. A 2-year-old male Amberjack farmed fish
At the maturity stage of the reproductive organs, the obesity degree is 18 or more, the body weight is 3.5 kg or more, and the reproductive gland index (GSI) is 0.5% or more and 10.0% or less.
After the reproductive organ maturation period, the obesity degree is 17 or more and the body weight is 3.5 kg or more, and the reproductive gland index (GSI) is lower than the reproductive organ maturity period value.
Amberjack farmed fish. The yellowtail farmed fish according to claim 8, wherein the GSI of the yellowtail farmed fish after the reproductive organ maturity is 2.5% or less. The yellowtail farmed fish according to claim 8, wherein the male yellowtail farmed fish in the reproductive organ maturity stage satisfies at least one of the following (1) to (3):
(1) The blood concentration of 11-ketotestosterone (11-KT) is 1800 pg / mL-4500 pg / mL,
(2) The blood concentrations of 17α, 20β-dihydroxy-4-pregnane-3-one (DHP) are 100 pg / mL to 450 pg / mL, and
(3) The blood concentration of estradiol (E2) is 130 pg / mL to 400 pg / mL. The amberjack farmed fish according to any one of claims 8 to 10, wherein the tail fork length is 50 cm or more. The yellowtail farmed fish according to any one of claims 8 to 11, which is yellowtail, amberjack, amberjack, or longfin yellowtail. Amberjack farmed fish obtained by the breeding method according to any one of claims 1 to 7.
How to raise mature yellowtail farmed fish, including.