The migrating route of Inshore bluefin tuna and fishing place!

Tuna caught in the coastal regions of the Japan Sea is notable as the best bluefin tuna in January. Iki, a small island in Kyushu area is one of the famous ports for tuna.

In February and March, the tuna auction market becomes slack due to rough weather. Just a few tunas from Nachikatsuura where is also the famous port for tuna are on the market.

In March and April, tunas become thin because their eggs need many nutrients.

In May, large tuna is seldom seen in the Tsukiji Fish Market. Even if there is, its body is really thin. “Kinkaimono” which means a shore-fish is generally considered as high-class tuna, but in this season, imported tuna is useful instead.

It is said that Pacific Bluefin tunas spawn around Japanese waters between Taiwan and Okinawa in April and May. And then, they go up to fertile, north sea along the eastern coast of Japan.

In June, “Chubo” which is young and small tuna is taken hugely off the coast of the Sea of Japan. The school of Chubo begin moving northward in this season.

In July and August, tunas can be seen occasionally but their bodies are still thin. Instead, Boston Tuna which is caught in the Atlantic Ocean and nicknamed “Jumbo” is on the market. Its fresh is softer than “Kinkaimono” and it doesn’t have medium-fatty part which “Kinkaimono” has.

In September, Boston Tunas are at their best with plenty of fat on them. The best season of Boston Tuna is limited and ends in October. But fortunately, Japanese tunas come into season.

The school of tunas split up into two groups, the one takes Pacific Ocean route and another takes the Japan Sea route and both of them move northward along the Japanese Islands. Some of them reach the Tsugaru Strait where and the season of Tuna begins from September to next January. Oma town and Toi town is famous nationwide for its catch of tuna from the Tsugaru Strait. The flavor of tuna in September is still weak but it becomes stronger in October. In November, feed of tunas such as Pacific saury or Japanese common squid with plenty of fat increase and flavor of tuna also gets stronger. In December, the peak season comes around.

A catch of tuna falls off in January and it enters the final season. The temperature of sea water gets cold and feed of tuna, squids decrease and the fishing season in this area ends.


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Revision date: August 20, 2018

What are Meji , Chubou and Maguro?

The bluefin tuna goes by different names in Japanese depending on its age. It starts out as “Meji,” grows into “Chubou” and finally is called Tuna (once it’s 50 kg or more).

Meji are less than 1 year old and weigh around 10 kg.

Chubou is an old word for relatively low-class Buddhist priests who were treated as errand boys. I guess it was meant to imply that these boys were even weaker than tuna. At this stage the fish are between 2-5 years old and weigh about 40kg.

Anything larger than that are called Maguro. The biggest is 3m long and 600kg or more. Especially large tuna are called Shibi. “Shibi” comes from the Japanese characters for “4-days”, which is how long the fish takes to mature.

Most meji and chubou are caught from May until the beginning of autumn when the tuna are thin and tasty.

Meji has its own unique scent and taste that sets it apart from full-grown tuna. The color is similar to the skipjack rather than bluefin. On the other hand, chubou has a lighter color and it isn’t as rich, but the flavor is young, refreshing tuna. That is why meji is considered to be a completely separate sushi topping and chubou is presented to be a type of tuna.


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Revision date: September 14, 2018

What is Uwami and Shitami?

Large fish that are caught are always kept and transported on their side with their heads facing left from the port to the market and to the restaurant where they are served. The part of the fish facing down when in this position is called “Shitami” or the “bottom body” and the part facing up is called “Uwami” or the top body. The Uwami costs more than Shitami. This is because the Shitami takes on the weight of the Uwami, reducing the freshness and possibly causing cracks in the body (cracking occurs on the edges of the muscles).


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Revision date: May 21, 2018

Why is sushi with tuna topping so expensive?

A purchase of raw tuna costs at least JPY 30,000 per kilogram. Furthermore, good tuna is judged not only by taste, but appearance is also highly regarded.

The surface is gradually oxidized by letting it sleep (mature) and the sushi chef makes sure that parts are cut of as they change color, when the timing is perfect for both the taste and appearance. In other words, skin is taken from the freshly purchased tuna, the meat of the fish darkened by blood (the blackened area that can’t be used as sushi toppings) is removed, the parts that have changed color are shaved off and then only the remaining, best parts used as toppings are left.

This is why the price is high.


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Revision date: February 5, 2018

Tuna was not a premium fish during the Edo period

During the Edo period, tuna was not highly valued as a sushi topping and it was referred to as “Gezakana” meaning that it was inferior to normal fish. The reason was the big size of the tuna. At this time there was no ice, so tuna had to be salted. It was cut into blocks, salt was spread all over and in it, and that was it. At Uogashi (the market prior to Tsukiji) it was treated at shops that specialized in salting fish. The dark, discolored, salty chunks of flesh really were nothing but “Gezakana*”.

*Gezakana -Relatively low-cost sushi ingredients, such as gizzard shad and horse mackerel. Bluefin tuna used to be also called gezakana in the Edo period, for losing its freshness easily.


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Revision date: December 30, 2017

You know fatty tuna, medium-fatty tuna and lean tuna, but have you heard of the more rare parts of the fish?

A single bite of the same bluefin tuna differs greatly depending on the part of the fish it came from.

The body of the fish is broadly categorized into the dorsal (back) and the ventral (belly) sides, which taste completely different. Of course the meat near the head tastes completely different from the meat near the tail. If you dig even deeper, there are parts that aren’t as well-known as the Ohtoro (fatty), Chutoro (medium-fatty) and Akami (lean) tuna meats. I’d like to explain those now.

Hachinomi” is the meat from the crown of the head. It is fatty and rich and also called “Head Toro”. Only about 1kg of this precious meat can be taken from even a very large fish, and it is only shared with regular, loyal customers.

Hohoniku” or cheek meat is taken from below the eye, seasoned, grilled and made into gun-kan rolls. The taste is enhanced in this part by grilling.

Kamatoro” is taken from behind the jaw. It is known as “shimofuri” or marbled meat. There are no veins in this part so the meat is soft and the marbling is more detailed than Ohtoro, so it is sticky and melts in your mouth. The balance of fat and sweetness in this part is unparalleled.

Chiai” is the part with the most veins, so it is a dark red color. It has a strong odor of blood and has multiple times the acidity of the lean meat, so it is not used as a sushi topping.

Chiai Gishi” is near the Chutoro and some say that it is the most delicious lean meat there is.

Wakaremi” is a precious part with very little meat found on the next to the dorsal fin. The part especially close to the dorsal fin is popular and called “Setoro” or back toro. The light taste is a combination of the deliciousness of both the lean meat and that won’t fill you up. However, this part is hard to get, even in high-quality tuna and is not available except to regular customers in almost all sushi restaurants.

If you are fortunate enough to get an opportunity to taste these , you can take it as proof that you have been accepted as a regular and loyal customer. It is difficult to distinguish these parts by appearance alone, so make sure you try them at a sushi restaurant you can trust. Just for your reference.


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Revision date: November 20, 2017