When it comes to tuna, many people think of Japan. Yes, as the world's number one consumer of tuna, Japan has the highest number of tuna in the world, both edible and caught, including bluefin tuna.
However, born to be fish, bluefin tuna is not destined to be born for the table, swimming skills and strength are the way to survive that they were once proud of.
Adult bluefin tuna are generally more than 2 meters long and weigh up to 300 pounds, and the largest recorded bluefin tuna caught by humans is 4.5 meters long and weighs 1360 pounds.
Bluefin tuna is large, belongs to the strength of the player, want to use the traditional fishing method to catch one, is definitely a human must lose the wrestling, but the development of modern fisheries has obviously turned the bluefin tuna power advantage into nothing, of course, this is the last word, in terms of strength alone, bluefin tuna in the sea can be called "overlord", they have to eat a lot of fish every day, in order to maintain the necessities of life.
Despite its large size, the bluefin tuna's body can be said to have been built for swimming.
First of all, the streamlined figure, the widest part of the bluefin tuna's body, the front and back ratio is 2:3, this shape is the most labor-saving for swimming;
Second, the strong tail, the bluefin tuna tail is thick and powerful, their body rarely swings left and right when swimming, but relies on the strength provided by the tail to go straight forward, which is both energy-saving and efficient;
Third, the fins that can be close to the body, the pectoral fin, dorsal fin, abdominal fin, etc. of the bluefin tuna can be retracted towards the body, thereby reducing the resistance when swimming. The bluefin tuna therefore swims very fast, about 60 km to 80 km/h, and has excellent endurance, swimming distances of about 150 km a day.
In addition, bluefin tuna can maintain their body temperature above the water temperature, between 25 degrees Celsius and 33 degrees Celsius, even in low temperature environments, their brains, vision, heart, muscles, and bones can function normally.
Such a big man born to swim does need to swim continuously, so that the water can flow into the gills and thus obtain oxygen, otherwise they will be starved of oxygen.
It is precisely because they always swim at high speed to obtain enough oxygen, the biggest difference between bluefin tuna and other fish is the content of hemoglobin and myoglobin in the blood, especially the concentration of hemoglobin can reach two to three times that of other fish, so their flesh is not only beef-like red, but also abnormally fat, fat content of up to 15%, melt in the mouth.
However, such a high fat content of bluefin tuna meat was not popular in the early days, because they belong to deep water fish, so the skin is very thin, with "blow bomb can be broken" somewhat exaggerated, but it is indeed easy to rot, once rotten and will emit a bad smell, so few people ask.
In North America before the 1960s, people would let go of bluefin tuna for photos, and even said that cats were not eaten, so the price was very low. At that time, Japan, during the boom of electronic product exports, the plane was full of goods across the ocean, but usually returned by empty plane, so some people came up with the idea of transporting low-cost bluefin tuna from North America back to Japan for canning.
At this moment, bluefin tuna ushered in a major change affecting "fish life", and bluefin tuna meat, which was labeled as "imported food", became people's favorite.
In the following time, with the blessing of the rapid development of freezing technology, nearly 80% of the captured bluefin tuna will enter the Japanese market, and the increasing demand has led to a surge in catch and price spikes, and bluefin tuna has gradually become a sought-after commodity.
Like what:
In 2011, 342 kilograms of bluefin tuna sold for $400,000, an average of $1,234 per kilogram;
In 2013, 222 kilograms of bluefin tuna sold for $1.76 million, an average of $7,927 per kilogram;
In 2019, 278 kilograms of bluefin tuna sold for $3 million, an average of $10,791 per kilogram.
It is this high price that makes bluefin tuna have the name of "gold with fins", and the price is synchronized with the price of one liter and then rise, which is the number of bluefin tuna falling again and again.
Compared with 30 years ago, the Atlantic bluefin tuna has been reduced by 90%, becoming an endangered species, the Pacific bluefin tuna has become a vulnerable species, the southern bluefin tuna has become a critically endangered species, it can be said that the three bluefin tuna days are not very good, from the perspective of the degree of threat to the population, they also have the "giant panda in the water", although the protection of wild bluefin tuna activities began very early, but early is not equal to good.
On the one hand, the action of protecting bluefin tuna, on the other hand, people's appetite, in order to take care of both, people began to breed in captivity, but the result is that neither effective protection, the taste is also disliked by many people.
There are two different ways to raise bluefin tuna in captivity, both of which are to get the fish back in the wild for artificial breeding, not to mention that this is another blow to the breeding of wild bluefin tuna populations, and breeding alone is not successful.
Specifically, there are two ways of captive rearing, one of which is to raise juvenile fish, that is, to catch small bluefin tuna that is more than a month old for farming, but this is not easy.
Bluefin tuna eat a lot of food, and picky eaters, according to the calculation of each 1 kg of bluefin tuna meat consumed by the feed fish reached 30 kg to 40 kg, the cost is high, not to mention, the survival rate of fish is still very low, because bluefin tuna needs a lot of deep space to swim, the living environment requirements are extremely high, a little discomfort will turn over, only 1% of the juvenile fish can survive until mature.
The second is to start farming from the fish eggs, which is also disproportionate to the input and output, you know, the probability of an egg growing into a fish is very low.
Female bluefin tuna can lay tens of millions of eggs a year, and the survival rate in the wild is not high in itself, and captive breeding is more and more difficult to encounter.
Regardless of the breeding method, the meat quality of artificially raised bluefin tuna is general, as we mentioned earlier, bluefin tuna must swim to breathe, which is not only related to the life of the fish, but also one of the guarantees of its excellent meat quality.
The artificial rearing water is not deep enough and not large enough, the fish can not swim at all, and the meat quality is greatly reduced, resulting in the fish not being sold at a good price, which makes people go back to catching wild bluefin tuna.
By the way, although bluefin tuna is "delicious", but its mercury content in the body is rising, methylmercury as a neurotoxin, will have an impact on the central nervous system, so eat less is better.
Finally, I would like to say that when we face fish, we often forget the simplest thing, they are first and foremost animals rather than food, which is not to make everyone, including myself, give up eating fish, but we should remember the truth that the ancients have long understood: "Fish without drying up, and hunting without burning forests." ”