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 Otoro (fatty), Chutoro (medium fatty) and Akami (lean) tuna meats. We’d like to explain those now.
“Hachinomi (ハチの身) or Tsunotoro Nouten” 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.
“Kamatoro (カマトロ)” is taken from behind the jaw. It is known as “shimofuri (霜降り)” or marbled meat. There are no veins in this part so the meat is soft and the marbling is more detailed than Otoro, so it is sticky and melts in your mouth. The balance of fat and sweetness in this part is unparalleled. It can be said that otoro (such as shimofuri and jabara) of tuna is the representative part of toro tuna. This is an image of the shimofuri on the right, and the jabara (蛇腹) on the left.
“Chiai (血合い)” 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 (血合いぎし)” －Located right next to chiai, this is the meat you can taste the umami of the rich red meat and the sweetness of toro fat at the same time.
“Wakaremi (分かれ身)” is a precious part with very little meat found next to the dorsal fin. The part especially close to the dorsal fin is popular and called “Setoro (背トロ)”. Setoro has both the umami of akami and the umami of fat. The fat isn’t overbearing so you can eat a ton. 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.
A sushi chef, Hiroyuki Sato, serves a tossaki hand roll as the first sushi piece of the course. “Tossaki (突先)” is an exclusive cut of tuna that goes well with sushi rice using red vinegar, which is less sour but has more umami and flavor compared with white vinegar. Because tossaki is the base of the tuna’s head and it moves a lot, there are a lot of muscular striations. Therefore it needs to be prepared using the back of a knife carefully as if peeling it off (Hagashi). It is said that tossaki is a high-tuna-flavor cut. A couple of Sato’s apprentices also offer a hand roll to open up the meal in the same way.
The meat of tuna gets leaner and muscular striations are fewer towards the inner center of the body. “Tenpa (天端)”, surrounding the spine, is deeper in color and tastes stronger. It features the tender texture coming from the finest meat quality. This is also called Tenmi (天身).
“Hohoniku (ホホ肉)” 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.
“Hireshita (ヒレ下)”－Located right above the first pectoral fin. Characterized with the tender meat which is relatively low in fat content but rich with umami flavor. This truly is the valuable part of whether there will be even enough for 10 pieces of sushi from an over 200 kg tuna.
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.
There are mainly five methods for tuna fishing. “Ipponzuri” (catching fish with fishing poles) in Oma, Aomori prefecture, you see a lot through the media, is well known. However, the fact is that Long line fishing method and Purse seine fishing method are the ones catching the most tuna. The rest is Fixed net fishing method and Hikiami (Seine fishing method).
<Long line fishing method>
To hang a long line (Mikinawa) in the sea, covered with about 3000 fishhooks attached to branch lines (Edanawa), aiming at a path of schooling tuna.
<Purse seine fishing method>
A large-scale method of fishing by encircling a school of tuna with a net. Although it is efficient, there is a demerit of lowering the quality of fish because they struggle while getting caught. In addition, other kinds of fish and immature fish can be caught without distinction and that leads to overfishing.
<Fixed net fishing method>
Tuna have a habit of migrating to the same ocean area at the same time each year. A coastal fishing method called Fixed net fishing consists of placing a net in the sea and wait for a school of tuna. The advantage of this method is to be able to capture the fish alive without causing any injury or damage.
<Ipponzuri (catching fish with fishing poles)>
This method has the longest history and uses a pole of 4 – 6 meters to fish from a boat. Using a machine that winds up lines automatically and also using human hands, pull up tuna that weighs more than 100kg and lastly catch it by piercing gills with a harpoon.
<Hikiami (Seine fishing method)>
To catch fish by towing a bag-shaped net from a boat.
The natural salmon roe season is the autumn. Does this mean that most of the roe eaten during the off-season is artificial Salmon roe. Not necessarily. As stated in his biography, even at the famous sushi restaurant Sukiyabashi Jiro, frozen roe is thawed as necessary.
Long ago this was an extremely expensive topping that ordinary people couldn’t afford, so artificial roe was used. There was a time when this was the case. But nowadays salmon roe is regularly imported from overseas and can be obtained cheaper, eliminating the need to use artificial roe instead.
However, we cannot overlook the commercial law for passing off artificial roe as natural roe. In Japan, the non-perishable properties of artificial salmon roe made from chemical substances (mainly sodium alginate) is utilized and used mainly in hospitals, but not sold to the general public. I’ll also tell you that it is very rare to find a sushi restaurant that serves artificial roe. Cheap roe is generally made from eggs of trout, other related species, or imported from Canada and other countries.
Unfortunately I’m not familiar with the state of things outside of Japan, but I can tell you how to tell the difference. All it takes is hot water and a moment of observation. Artificial salmon roe will show no changes in hot water, but natural roe will start to turn white on the surface. This is due to the protein reacting and changing with the heat. That said, this is not an experience you can just set up at the sushi restaurant.
As an aside…
What are the fish eggs on sushi called in Japan?
There are eight types of fish eggs served at Japanese sushi restaurants. However, not all of them are used for Nigiri sushi. Some are served as side dishes. Uni is sometimes translated as sea urchin’s roe, but it is actually the sea urchin’s genitals (testes and ovaries). Most people also don’t know that Tobiko and Tarako are not served at 99% of Edo-style restaurants. In other words, these toppings are only served at kaiten-sushi (conveyor belt) restaurants. The one type of roe topping that can probably be found at all sushi restaurants is Ikura. Even more types of fish eggs, such as Masago, Paddlefish roe and Hackleback roe are used in sushi overseas, but Japan remains more conservative. Of course, it’s only natural that fish substitutes are not well-received in the place where sushi was born.
Types of fish roe
What is Ikura? － It is Salmon roe.
What is Kazunoko? － It is Herring eggs.
What is Sujiko? － It is Salmon roe that is still within its egg membrane.
What is Tobiko? － It is Flying fish roe.
What is Tarako? － It is Walleye pollock roe.
What is Caviar? － It is Sturgeon roe.
What is Karasumi? － It is Dried mullet roe.
What is komochi konbu? － It is Herring spawn on kelp.