WO2007097416A1

WO2007097416A1 - Method of growing farmed fish

Info

Publication number: WO2007097416A1
Application number: PCT/JP2007/053388
Authority: WO
Inventors: Masashi Ando; Masashi Nakao; Yasuyuki Tsukamasa; Kenichi Kawasaki; Manabu Seoka; Masahiro Nakatani; Yoshifumi Sawada; Shigeru Miyashita; Tokihiko Okada
Original assignee: Kinki University
Priority date: 2006-02-24
Filing date: 2007-02-23
Publication date: 2007-08-30
Also published as: JP4035737B2; JP2007222150A

Abstract

A method of growing farmed fish which comprises feeding the fish with a bait and/or a feed comprising fish(es) and having a total mercury concentration of 0.1 μg/g or less. According to this method, mercury contained in farmed fish bodies can be reduced and highly safe farmed fish can be provided in farming expensive fish such as Thunnus thynnus.

Description

Specification

Farmed fish production method

Technical field

[0001] The present invention relates to a method for producing cultured fish with low mercury concentration.

Background art

[0002] In recent years, the concentration of mercury in water has increased due to water pollution of seawater, rivers, lakes and marshes due to deterioration of the global environment, especially polluted wastewater. As a result, mercury in the water is taken up by plantatons that inhabit the water, and is gradually concentrated by the food chain of the organism. As a result, as the top of the food chain is reached, high-concentration mercury pollution occurs. If fish containing such a high concentration of mercury is used for food, pollution such as so-called Minamata disease will occur.

[0003] In Japan, the Ministry of Health, Labor and Welfare has established that the safety standards for mercury levels in edible fish are based on the Food Safety Act. The provisional regulation value is set so that the concentration of the total amount is 0.4 gZg or less. In particular, for mercury that is highly toxic and dangerous for the human body, a regulation is set for the mercury concentration to be 0.3 g Zg or less, and it is legally stipulated that general fish containing methyl mercury exceeding this limit should be disposed of. It has been. However, for tuna, swordfish, bonito, and deep seafood, the mercury concentration is high, but for general consumers, it is out of regulation because of low food intake.

[0004] Tuna, such as naturally occurring bluefin tuna, vary depending on the fish species, habitat, fishing ground, season, etc., but usually a high total mercury concentration of 0.2 to 6 / z gZg is detected from the edible part. The Thus, the high total mercury concentration detected in tuna is because the tuna is located at the top of the food chain in fish, and the mercury contained in the ingested fish is sequentially concentrated and taken into the body. It is known that it is the result of being accumulated in the body without being excreted. For this reason, as described above, the regulation value of mercury concentration for general fish cannot be applied to tuna, but it is simply a low amount of food intake. It is a problem. [0005] For many years, the inventors of the present application have dealt with the resource culling of tuna, which are high-grade fishes, in terms of the complete aquaculture of bluefin tuna, such as egg collection, fertilization, hatching, and fry farming to adult fish. I'm working on research. As a result of research, we have finally reached the stage of shipping 3-year-old fish weighing 20-60 kg, which have been produced in complete aquaculture in recent years, to the farm.

Disclosure of the invention

Problems to be solved by the invention

[0006] Naturally occurring tuna are thought to prey on mackerel and squid mainly in the ocean. For this reason, conventionally, in the tuna culture, mackerel prefers to feed, but mackerel that is supplied at low cost with high catch is mainly fed. However, mackerels vary depending on the fish species, fishing grounds, seasons, etc., where the mercury concentration is relatively high, but the total mercury concentration is usually about 0.2 to 0.3 gZg. For this reason, naturally occurring tuna grown with mackerel have a total mercury concentration of around 1 μgZg.

[0007] In conventional tuna farming, the selection of fish for feeding is a factor that mainly takes into account the preference and cost (cost) of tuna, and considers the mercury concentration of fish for feeding. It has not been. Therefore, in reality, when a large fish species such as tuna is cultivated, the feeding fish is limited to the natural mackerel mentioned above, and a large amount of mackerel is caught and obtained at low cost. It is common to purchase a large amount of mackerel at a time when it is obtained, store it in a freezer, and thaw it sequentially to use it for feeding. In the cultivation of tuna, since satin feeding is performed until the tuna is no longer eaten, if the feed with high mercury concentration continues to be fed, the concentration of mercury accumulated in the tuna body will increase. The safety standards set by the Ministry of Health, Labor and Welfare for general fish may be exceeded.

[0008] Currently, the regulation value of mercury concentration does not apply to tuna, so bluefin tuna containing a fairly high concentration of mercury can be shipped to the market. While reducing the concentration of mercury, which is a very dangerous substance for the human body, in the body of the cultured fish, the safety of food is increased, and the safe cultured fish that consumers can purchase and eat with peace of mind. Production is the social responsibility of the fisherman.

[0009] The present invention has been made to solve the above-described problems, and an object of the present invention is to produce cultured fish with reduced mercury concentration in the body and improved safety. Is to provide a method.

Means for solving the problem

[0010] In order to achieve the above objective, the present inventors conducted research on the complete culture of bluefin tuna, and as a result of repeated aquaculture tests with various types of feeding fish and their feeding methods, By selecting the type of fish, the concentration of mercury accumulated in the body of bluefin tuna can be reduced, and by devising its feeding method, it is a fish species with a low mercury concentration. The inventors have found that it is possible to efficiently feed bluefin tuna having a low mercury concentration by increasing the growth rate by feeding bluefin tuna with a large amount of food that is not eaten, thereby completing the present invention. That is, the present invention is as follows.

[0011] The method for producing cultured fish of the present invention is characterized in that the fish is cultivated by feeding food and Z or feed using fish having a total mercury concentration of 0.1 μgZg or less.

[0012] Here, it is preferable to use fish with a pre-measured total mercury concentration of 0.1 μgZg or less for feed and Z or feed, and the pre-measured total mercury concentration is 0.04 / z gZg or less. More preferred to use the lower fish for feed and Z or feed.

[0013] The cultured fish in the method for producing cultured fish of the present invention is more preferably a bluefin tuna, which is preferably a tuna.

[0014] In addition, in the method for producing cultured fish according to the present invention, it is preferable that the fish used for the feed and Z or the feed contains a horse mackerel. In this case, the horse mackerel is more preferably a mackerel.

[0015] Further, in the method for producing cultured fish of the present invention, the fish used for the feed and Z or the feed may be horse mackerel and squid. In this case, feed with zebrafish and feed with z or feed, and feed fish with zodiac and feed with z or feed when the farmed fish begins to eat feed with zander and z or feed Switching, farming When fish no longer eat feed and z or feed using horse mackerel, switch to feeding and feeding Z or feed using eelfish, and feed and Z or feed using cultured fish silkworms It is preferable to repeat the feeding method to switch back to feeding and feeding Z or feed again with horse mackerel at the beginning.

The invention's effect

[0016] According to the present invention, farmed fish with reduced mercury concentration can be produced. Brief Description of Drawings

[0017] [Fig. 1] A graph showing the relationship between bluefin tuna weight feeding and changes in total mercury concentration in muscle for bluefin tuna fed with sesame mackerel and bluefin tuna fed with horse mackerel and squid. Yes, the vertical axis is total mercury concentration (ppm), and the horizontal axis is body weight (kg).

[Fig. 2] A graph showing the amount of feed per bluefin tuna per month obtained in Example 1, with the vertical axis representing the amount fed (kg) and the horizontal axis representing the period from June to December. is there.

FIG. 3 is a graph showing the mercury intake per bluefin tuna per month obtained in Example 1, with the vertical axis representing mercury intake (mg) and the horizontal axis from June to December. Each period.

[Fig. 4] Graph showing the mercury intake per kg of bluefin tuna per month, obtained in Example 1, with the vertical axis representing mercury intake g) and the horizontal axis representing each period from June to December. It is.

[Fig. 5] A graph showing the amount of feed per bluefin tuna per month obtained in Comparative Example 1, with the vertical axis representing the amount fed (kg) and the horizontal axis representing the period from June to December. is there.

FIG. 6 is a graph showing the mercury intake per bluefin tuna per month obtained in Comparative Example 1, with the vertical axis representing mercury intake (mg) and the horizontal axis from June to December. Each period.

[Fig. 7] Graph showing the mercury intake per kg of bluefin tuna per month, obtained in Comparative Example 1, with the vertical axis representing mercury intake g) and the horizontal axis representing each period from June to December It is.

FIG. 8 is a diagram schematically showing the division of the part of bluefin tuna fish 1 used in Example 2 and Comparative Example 2.

FIG. 9 is a graph showing the mercury concentration of each part of the bluefin tuna obtained in Example 2, and the vertical axis represents the mercury concentration (ppm).

FIG. 10 is a graph showing the mercury concentration of each part of the bluefin tuna obtained in Comparative Example 2, with the vertical axis representing the mercury concentration (ppm).

Explanation of symbols

[0018] 1 fish body, 2 front part, 3 back part, 4 back part, 5 front part, 6 middle part, 7 back part, 8 tail part.

BEST MODE FOR CARRYING OUT THE INVENTION

[0019] The method for producing cultured fish according to the present invention is characterized in that the fish is cultured by feeding food and Z or feed using fish having a total mercury concentration of 0.1 μgZg or less. In the present invention Examples of farmed fish include, but are not limited to, tuna, swordfish and bonito. Among them, bluefin tuna, particularly preferred are bluefin tuna such as bluefin tuna, southern bluefin tuna, albacore, bigeye, yellowfin, yellowfin tuna and cocinaga.

[0020] In the present invention, "food" refers to raw food for feeding, and refers to fish itself having a total mercury concentration of 0 .: gZg or less. In the present invention, “feed” means a mixed feed for feeding, and refers to fish meal processed using fish having a total mercury concentration of 0.:gZg or less. In the method for producing cultured fish of the present invention, such feed or feed may be used alone or of course. In the present invention, the total mercury concentration in the edible part of farmed fish is the provisional regulation value for general fish by feeding with feed and Z or feed using fish with a total mercury concentration of 0.:gZg or less. Can be reduced to 4 gZg or less

. From the viewpoint of producing safer cultured fish with a lower mercury concentration, it is preferable to use fish with a total mercury concentration of not more than 0.04 gZg for feed and Z or feed.

[0021] Figure 1 shows the relationship between bluefin tuna weight-fed and changes in total mercury concentration in muscle for bluefin tuna cultivated by feeding sesame mackerel and bluefin tuna cultivated by feeding horse mackerel and squid. The vertical axis represents total mercury concentration (ppm) and the horizontal axis represents body weight (kg). Figure 1 shows that the bluefin tuna cultivated mainly by feeding sesame mackerel up to a weight of 3 kg is divided into two test plots. As a result of measuring the total mercury concentration in the edible part of each bluefin tuna that were fished in a mixed growth period and fished until the weight reached about 9 kg, and each bluefin tuna belonging to both test zones was picked up at regular growth periods. (In Fig. 1, the result when feeding sesame mackerel continues is shown by a solid line, and the result when feeding mackerel and squid is shown by a broken line). In addition, the average total mercury concentration of sesame mackerel is about 0.18 g Zg, and the average total mercury concentration of horse mackerel and squid is about 0.04 g Zg.

[0022] FIG. 1 shows that the total mercury concentration of the bluefin tuna that continued to feed sesame mackerel gradually increased while growing to a weight of 9 kg. If you continue to feed sesame horse mackerel to a weight of 20-30 kg, the total mercury concentration will gradually rise to an average value of about 0.5 / z gZg (not shown). On the other hand, bluefin tuna cultivated with a mixed feeding of horse mackerel and squid, a fish with a weight of 3 kg and a total mercury concentration of 0.1 μgZg or less In Figure 1, the total mercury concentration gradually decreases with increasing body weight, and it is shown in Fig. 1 that safe bluefin tuna with a total mercury concentration of 0.3 µ _& Zg or less can be produced reliably.

[0023] In the method for producing cultured fish of the present invention, the total mercury concentration is measured in advance for a candidate group of fish used for feed and Z or feed, and the measured total mercury concentration is 0.1 l ^ g / g or less ( Preferably, 0.04 μgZg or less fish is selectively used for feed and Z or feed. The total mercury concentration in the candidate group of fish used for feed and Z or feed can be determined by, for example, killing and exsanguinating these fish immediately, mincing the muscles removed in several parts, and then adding nitric acid and sulfuric acid. It can be measured by using an atomic absorption photometer equipped with a mercury reduction vaporizer after wet decomposition using. The mercury concentration in fish varies depending on the fish species, fishing grounds, and seasons, but for certain fish species that are landed in certain fishing grounds in certain seasons, it has a substantially constant mercury concentration. Therefore, if these data are prepared as a database, fish with a total mercury concentration of 0.1 μgZg or less that can be used in feed and Z or feed can be easily selected. It can be obtained.

[0024] Examples of fish having a total mercury concentration of 0.1 μgZg or less that can be used as feed and Z or feed in the present invention include horse mackerel, mud horse mackerel, squid, squid, squid, etc. It is done. In the method for producing cultured fish of the present invention, among these, horse mackerel having a particularly low total mercury concentration, especially horse mackerel, can be used for feed and Z or feed.

[0025] However, if the farmed fish is a tuna such as bluefin tuna, the tuna is very weak in preference for horse mackerel. When feed is used with horse mackerel and Z or feed alone However, it is difficult to feed a sufficient amount necessary for the rapid growth of tuna, even when fed with satiation. On the other hand, squid squid with a total mercury concentration of 0.1 μgZg or less is more expensive than tuna, but is expensive compared with horse mackerel, It is not practical to grow tuna using z or feed alone.

[0026] From this point of view, in the method for producing cultured fish of the present invention, when the cultured fish is a tuna (especially a bluefin tuna), both a horse mackerel (especially a horse mackerel) and a locust are used as a feed and z. Or it is preferable to use for feed. In this way, tuna are eaten in large quantities by feed and / or feed using horse mackerel and feed and / or feed using horse mackerel. This makes it possible to feed tuna with large amounts of feed and Z or feed using horse mackerel.

[0027] In addition, the present inventors use the following method when cultivating tuna by mixing and feeding feed and Z or feed using a horse mackerel and feed and Z or feed using eelfish. By adopting it, it is a fish with low total mercury concentration, but tuna are generally preferred and do not eat, but feed with fish and Z or feed are fed in large quantities to make tuna It was found that tuna with reduced total mercury concentration can be produced efficiently while increasing the growth rate. In other words, when using tuna to feed tuna with feed and Z or feed and squid using a horse mackerel, and feeding the feed and Z or feed together, feed the feed and Z or feed using squid first. When the feed and Z or feed using tuna silkworms begins to be fed, switch to feed and Z or feed using horse mackerel, and tuna feed and Z or feed using horse mackerel When no longer ingestion of food, switch to feeding with squid and Z or feed, and when feeding with maggot power eelfish and Z or feed begins, feed and Z with horse mackerel again Or it is preferable to repeat the feeding method to switch to feeding.

[0028] In the feeding method described above, by first feeding feed using eel and Z or feed, the appetite of the tuna is stimulated, and the tuna eats in competition. In this way, when the tuna begins to eat, the feed and Z or feed are switched to the feed and Z or feed using horse mackerel, so that for a while the tuna will feed and use the horse mackerel Continue eating Z or feed vigorously. After a while, the tuna no longer eat the feed and Z or feed using horse mackerel, so the feed and Z or feed using a small amount of locust were added and fed again, and the tuna began to compete for feeding. At that time, feed again with feed and Z or feed with horse mackerel. By repeating this and feeding feed and Z or feed using eelfish and feed and Z or feed using horse mackerel alternately, feed and Z or feed using horse mackerel are increased in tuna. The amount of food can be fed, and feeding with mainly horse mackerel and feeding with Z or feed enables efficient and economical aquaculture of tuna. As a result, extremely safe cultured tuna with extremely low mercury concentration, which is not found in naturally occurring tuna with high mercury concentration, can be provided to the market at a relatively low price, and the commercial value of cultured tuna is low. Extremely high.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not intended to be limited thereto.

The upper part of the bottomed cylindrical cage surrounded by a net with a diameter of about 30m and a depth of about 10m is floated on the surface of the sea, and the whole is installed under the sea surface, and about 1000 bluefin tuna with an average weight of 3kg are released in this, total mercury concentration The fish were cultured using horse mackerel and eelfish, both of which were less than 0.1 μgZg, as feed. The aquaculture started on June 1 and continued until December 31. Feeding horse mackerel and sea cucumber is a satiety feed.Specifically, feeding the sea bream first, switching to horse mackerel feeding when bluefin tuna begins to feed, and a small amount when bluefin tuna stops feeding Feeding squid again, and when the bluefin tuna began to feed, switching to horse mackerel feeding, the salmon feeding method was repeated.

[0031] FIG. 2 is a graph showing the amount of feeding per month of bluefin tuna, obtained in Example 1, with the vertical axis representing the amount fed (kg) and the horizontal axis representing June to December. Each period. Fig. 3 is a graph showing the mercury intake per bluefin tuna per month obtained in Example 1, with the vertical axis representing mercury intake (mg) and the horizontal axis from June to December. Each period. Fig. 4 is a graph showing the mercury intake per kg of bluefin tuna per month obtained in Example 1, where the vertical axis is mercury intake g), and the horizontal axis is from June to December. Each period. In addition, the mercury intake per bluefin tuna per month shown in Fig. 3 is the result of calculating the feeding amount shown in Fig. 2 and the concentration of total mercury contained in horse mackerel and eelfish. Mercury intake per kg of bluefin tuna per month shown is calculated by dividing the results shown in Fig. 3 by the average body weight of bluefin tuna. In each of Figures 2-4, each period on the horizontal axis is one month (ie, for example, “June-July” is displayed for one month in June, and “July-August” is displayed for seven months. Means one month of the month). In addition, as shown in Figure 2, the amount of feeding increased from June to October This is because the amount of food intake increases as the weight of bluefin tuna increases. On the other hand

In December, when the temperature drops, food consumption will drop. From the results shown in Fig. 2 to Fig. 4, when the fish were fished with a total mercury concentration of 0.1 μgZg or less and fed with salmon or feed, the total mercury was increased as the body weight increased. It can be seen that the concentration decreased gradually and safe bluefin tuna with a total mercury concentration of 0.3 gZg or less was produced.

[0032] <Comparative Example 1>

Bluefin tuna was cultured in the same manner as in Example 1 except that about 1,000 bluefin tuna with an average weight of 6 kg were released and sesame mackerel was fed. Fig. 5 is a graph showing the amount of feeding per bluefin tuna per month obtained in Comparative Example 1, with the vertical axis representing the amount fed (kg) and the horizontal axis representing the period from June to December. It is. Fig. 6 is a graph showing the mercury intake per bluefin tuna per month obtained in Comparative Example 1, with the vertical axis representing mercury intake (mg) and the horizontal axis representing June to December. Each period. Further, FIG. 7 is a graph showing the mercury intake per kg of bluefin tuna per month obtained in Comparative Example 1. The vertical axis is mercury intake (g), and the horizontal axis is from June to December. Each period. From the results shown in Fig. 5 to Fig. 7, when the bluefin tuna is cultured by feeding sesame mackerel with a total mercury concentration exceeding 0.1 l ^ g Zg, it can be shipped as a 3 year old with a weight of 20-60 kg. When cultured to fish, the total mercury concentration in the edible portion is considered to reach 0.2 to 0.5 gZg, which is a provisional regulation value for the total mercury concentration of general fish. It turns out that there is a risk of exceeding 4 gZg.

As shown in Fig. 8, the bluefin tuna, which were cultivated by feeding with horse mackerel and eelfish as in Example 1, and were picked up every month from June to January of the following year and shipped to the fishing ground, as shown in Fig. 8. Divide 1 into 7 parts: anterior part 2, back part 3, back part 4, abdominal part 5, abdominal part 6, abdominal part 7 and tail part 8 and measure the mercury concentration in muscle of each part did. The mercury concentration was determined by dividing the immediately killed / bleeded bluefin tuna into the above-mentioned parts, mincing the extracted muscles, wet-decomposing them with nitric acid and sulfuric acid, and then using an atomic absorption photometer equipped with a mercury reduction vaporizer. And measured. FIG. 9 is a graph showing the mercury concentration of each part of the bluefin tuna obtained in Example 2, and the vertical axis represents the mercury concentration (ppm). Fig. 9 shows the average value of mercury concentration data at each site aggregated every month. The T-shaped line protruding at the top of the graph shows the standard deviation of the data. From Fig. 9, the total mercury concentration is 0: L gZg or less, and when farming is conducted using horse mackerel and squid as feed, the concentration of mercury in each part of bluefin tuna is 0.3 gZg or less. It can be seen that the total mercury concentration in the food section is below the provisional specified value for the total mercury concentration applicable to general fish.

[0034] <Comparative Example 2>

For the bluefin tuna cultivated by feeding with sesame mackerel, the concentration of mercury contained in the muscle of each part was measured in the same manner as in Example 2. FIG. 10 is a graph showing the mercury concentration in each part of the bluefin tuna obtained in Comparative Example 2, with the vertical axis representing the mercury concentration (ppm). Figure 10 also shows the average value of mercury concentration data at each site, which is tabulated every month. In Fig. 10, the T-shaped line protruding at the top of the bar graph shows the standard deviation of the data Is shown. From Figure 10, when cultivated using sesame mackerel as a feed, the total mercury concentration in the edible part is about 0.5 / z gZg, and the provisional provisional value for the total mercury concentration applicable to general fish is shown. You can see that it exceeds.

[0035] The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims

The scope of the claims

[1] A method for producing cultured fish that uses fish with a total mercury concentration of 0.1 μgZg or less and feeds fish and straw or feed to cultivate fish.

[2] The method for producing cultured fish according to claim 1, wherein a fish having a total mercury concentration measured in advance of 0.1 μgZg or less is used for feed, salmon or feed.

[3] The method for producing a cultured fish according to claim 1, wherein fish having a total mercury concentration measured in advance of 0.04 μgZg or less is used for food, salmon or feed.

[4] The method for producing cultured fish according to claim 1, wherein the cultured fish is a tuna.

[5] The method for producing cultured fish according to claim 4, wherein the fish is tuna tuna.

[6] The method for producing cultured fish according to claim 1, wherein the fish used in the feed and Z or feed contains horse mackerel.

[7] The method for producing cultured fish according to claim 6, wherein the horse mackerel is a horse mackerel.

[8] The method for producing cultured fish according to claim 1, wherein the fish used in the feed and Z or the feed is horse mackerel and squid.

[9] Feed fish and Z or feed using squid, and feed fish and Z or feed using horse mackerel when the farmed fish begins to feed and feed Z or feed Switch to the feed and Z or feed feeding with eelfish when the farmed fish stops eating feed and Z or feed with horse mackerel, and the farmed fish with 15 and Z or feeding with squid 9. The method for producing cultured fish according to claim 8, wherein the feeding method is switched again to feed using Zhi and feed of Z or feed when feeding is started.