Salmon is a popular sushi topping throughout the world, but there are actually a wide variety of types. Do you know the difference? Read on to learn the details about the salmon you always eat.
There are 8 types of salmon used as food in the world
The following are the 8 basic types of salmon popular for eating throughout the world. However, academically you could say there are 12 types. In Japanese salmon is referred to as “鮭” (sake/salmon) or “鱒” (masu/trout). The characters look different, but they are part of the same family and there aren’t clear biological categories to separate them into. Incidentally, in English the type that makes their way into the sea is called “salmon,” and those that remain in freshwater their entire lives are known as, “trout.” In this article, they are all considered to be part of the salmon family.
Let’s look a bit closer at the 8 types of salmon
King salmon (Also called Chinook salmon or Spring salmon)
Scientific name: Oncorhynchus tshawytscha (Walbaum)
Japanese: Masunosuke. This is the largest of the salmon family. It is found over a wide area, mainly in northern parts of the Pacific Ocean such as Alaska as well as the Okhotsk Sea, northern Japan Sea. They don’t swim upstream in Japan’s rivers, but a small number are fished along the Pacific coast of Hokkaido while migrating. They are also farmed in the US, Canada, Australia, Chile, etc.
Chum salmon (Also called Dog salmon)
Scientific name: Oncorhynchus keta (Walbaum)
Japanese: Shirozake (Sake). This is what people refer to when they mention salmon in Japan. Even among Japanese, opinions vary regarding the pronunciation of Salmon. These are the two basic ways: “sake” and “shake”. “Sake” is more commonly used, but “shake” is also not a mistake. They migrate from Okhotsk, Kamchatka and the Bering Sea to the Gulf of Alaska, spend 3-5 years in the northern Pacific Ocean, then return to Japan’s rivers. This refers to the Akiaji or Akisake (chum salmon) that come to the Tohoku and Hokkaido coastal regions during the spawning season, which spans from September to November.
About the many names for “Chum salmon”
Chum salmon may be called other names depending on when it was caught, how mature the body is, and taste. Young salmon born in Russian rivers, that are somehow mixed in with the salmon returning to Japan to spawn are called “Keiji”. Chum salmon caught between Spring and Summer during recurrent migration is called “Tokishirazu”, which means ‘unaware of time’, or just Toki. On the other hand, Chum salmon, who are returning to the coast and are preparing to spawn are called “Mejika” and, the Chum salmon gathered around river outlets who are about to spawn are called “Akiaji” or “Buna” which means ‘beech–as in the tree’ and Chum salmon that has already spawned is called “Hocchare”.
About Change in Appearance and Quality Chum salmon
Chum salmon migrating in the ocean (Keiji, Tokishirazu, Mejika, etc.) are collectively called “Ginke” and both males and females are a shiny silver color. The roe of the Ginke is a sticky yellow, similar to chicken eggs. The egg membrane is removed from this to make the “Ikura” or salmon roe used as a sushi topping. The Ginke also has a relatively gentle face. Migrating Sakuramasu and Masunosuke also have the same sort of silver body.
Meanwhile, Chum Salmon gathered at river outlets (Akiaji, Buna, etc.) are mostly shown nuptial coloration (this is the red-purple and block coloring called Bunake or Buna), and the snout of the males start to curve. As the female approaches her spawning time, the black stripes on her sides from the head to the tail really start to stand out. When the Chum salmon drinks river water, the taste starts to decrease rapidly. Fully matured roe of the ‘buna’ rank of Chum salmon have a tough surface like a ping pong ball just before hatching so it doesn’t burst easily in the mouth and the flavor is watered down, so they aren’t suitable to eat. In other words, the roe of the salmon that have already swum upstream is not suitable for making sushi. The name ‘buna’ comes from the color of the body of salmon, which is similar to the color of the bark of a beech tree.
Due to the variety in the color of the meat at markets, even among the same buna, there are even more detailed categories.
A Buna: Salmon that are 15 to 30 days away from spawning and caught at the river outlet. The body surface is a silvery-white color, but some of the nuptial colorings starts to appear.
B Buna – Salmon that has just started to swim upstream. The nuptial coloring is getting a bit stronger.
C Buna – The flavor has decreased a lot by this point, so this is the lowest grade of salmon at a market. The nuptial colors are strong and black stripes are apparent on the body.
Pink salmon (Also called Humpback salmon)
Scientific name: Oncorhynchus gorbuscha (Walbaum)
Japanese: Karafutomasu. These fish are distributed widely from California to Alaska, the Korean peninsula and Hokkaido. In Japan, they primarily swim upstream in the rivers around the Okhotsk Sea and Nemuro Channel. As a food, the body is soft and it is often canned.
Silver salmon (Also called Coho salmon)
Scientific name: Oncorhynchus kisutch (Walbaum)
Japanese: Ginzake. Wild Silver salmon inhabit the Northern Pacific ocean regions and don’t swim upstream in Japan’s rivers. Most of the Silver salmon currently in circulation has a stable supply from aquaculture. They are primarily used for processing and the price is a bit lower.
Red salmon (Also called Sockeye Salmon or Kockanee)
Scientific name: Oncorhynchus nerka (Walbaum)
Japanese: Benizake. Red salmon are distributed throughout the northern Pacific Ocean, Okhotsk Sea and the Bering Sea. There are no wild Red salmon born naturally in Japan’s rivers. They are the same in that they are born in rivers, grow in the sea, then return to the river, but a unique characteristic is that they spend years in a lake they come across partway through the river. Therefore, in order to breed Red salmon, there must be a lake on their upstream route. The aquaculture hasn’t been established for this type, so they are all wild. They are mainly used in canned, frozen, or salted fish. They are also deliciously smoked.
Atlantic salmon (Also called Black salmon)
Scientific name: Salmo salar Linnaeus
Japanese: Taiseiyosake. Natural Atlantic salmon are widely distributed around the North Atlantic and its tributaries. Farmed Atlantic salmon are chilled from their locales, then distributed by air. They are never frozen, so they have a relatively nice texture and they are characterized by the fat content and delicious-looking color. It is the most expensive type of farmed salmon. They are also the first fish farmed in seawater in Europe.
Rainbow trout (Also called Steelhead)
Scientific name: Oncorhynchus mykiss (Walbaum)
Japanese: Nijimasu. Rainbow trout is native to the streams of the west coast of North America. They are named for the wide vertical shiny, rainbow stripe on the side of their bodies. Salmon that are small and always stay in streams are called Rainbow trout. The larger type that lives in the sea, spawns in rivers, and has a black mark on the top of their heads are called Steelhead. The two names show that they were thought to be different fish. In Japan, they are primarily farmed in freshwater.
This is a combination of the Rainbow trout that descend to the sea and the Rainbow trout that live their entire lives in freshwater, and are farmed in seawater. Generally, they are distributed frozen, as fillets. This is the type that is just called, “salmon” at conveyor belt sushi restaurants. Production is stable, they are cheap and taste good. They are characterized by not having the strong odor that salmon is known to have. The product is also called Trout salmon.
Main types of salmon used in sushi throughout the world
Almost all of the salmon used as a topping at sushi restaurants throughout the world are Salmon trout farmed in the sea in Chile, Norway, etc., or Atlantic salmon farmed in the seas in Norway, Australia, etc.
Main types of salmon used in sushi in Japan
In the first place, salmon is a sushi topping that isn’t used as a normal nigiri topping at sushi restaurants in Japan (see here for the reason). However, lately, at conveyor belt sushi, it has become the most popular topping by far. The beautiful coloring and the soft fatty texture suit the taste of people today. These are mostly Salmon trout and Atlantic salmon. However, in Japan, it is considered to be a specifical conveyor belt sushi topping and there are still very few Edo-style sushi restaurants that serve sushi with Salmon trout or Atlantic salmon toppings.
However you will find some top-grade sushi restaurants that serve rare salmon sushi toppings such as Masunosuke, Tokishirazu, Keiji and Sakuramasu caught during migration off the shores of Hokkaido, etc. Be careful when ordering salmon sushi in high-end sushi restaurants. One reason is that it’s likely they don’t stock such a thing (meaning Salmon trout and/or Atlantic salmon), and don’t forget that some older chefs may be annoyed at such an order.
Let’s also take a look at some rare types of salmon
The Japanese “Masunosuke,” refers to King salmon. This is the largest of salmon with especially high-fat content and it is definitely the king of salmon when it comes to taste as well. There are only a few available for fishing along the coast of Hokkaido, etc. and they are extremely expensive. The peak season is from spring to early summer. The image on the right is masunosuke sushi.
Tokishirazu (時不知 or 時鮭)
The Japanese “Tokishirazu” refers to Chum salmon. Tokishirazu is salmon caught from spring to the beginning of summer. They are the same chum salmon found in the fall, but since they aren’t caught during the spawning season, the fish don’t have eggs or milt, and instead have a high-fat content. The name “Tokishirazu” stems from the fact that these fish are caught out of season, in summer and the name means ”ignorant of time”. The image on the right is tokishirazu sushi.
The Japanese “Keiji” refers to Chum salmon. Keiji is young salmon with immature ovaries or testes. Only 1-2 Keiji are found in a normal catch of 10,000 salmon. Normal salmon fat content is 2-15% but the Keiji has a very high body fat percentage at 20-30%. Keiji is found mixed in with the chum salmon, caught in the fixed shore nets for fishing things like Shiretoko and Abashiri, so the salmon swimming upstream in the Russian rivers are said to have “strayed off course”. Keiji is a fish weighing up to only about 4 kg. The price range is between 500 and 2.000 US dollars per fish. The image on the right is keiji sushi.
Scientific name: Oncorhynchus masou (Brevoort)
Sakuramasu is an endemic species to Japan, so the English name is a direct transliteration of the Japanese pronunciation. They are caught in the rivers near the estuaries when swimming upstream. Normally they spend a year and a half in the rivers then descend to the sea in the spring. After migrating in the ocean for a year, they return to their home river to swim upstream the next spring. In contrast, the type that stays in the river without descending into the sea is called Yamame. The taste is supreme when eaten raw, but there is a risk of parasites so they are frozen immediately after catching, just in case, and then used as a sushi topping after a certain amount of time has passed. It has a strong umami flavor and a perfect sweetness. The peak season is spring. The image on the right is sakuramasu sushi.
Chum salmon that have come back for spawning and are caught in a fixed shore net about 25 to 60 days away from spawning. They are caught together with Akiaji, but the space between the eyes and the snout is narrow so it is called Mejika (near to the eyes). There is more fatty meat than Akiaji and it isn’t caught in as high volume so the price is higher. Mejika costs about double what Akiaji costs.
Is salmon a red fish? Or is it a white fish?
The characteristic orange-red color of salmon meat comes from carotenoid fat-soluble pigments, especially astaxanthin. The components of these pigments are the same as the red coloring in the shells of shrimps and crabs. In the case of shrimps and crabs, in some cases, the red coloring isn’t apparent until protein combines with the pigment components through heat, but these pigment components are the same as those that give salmon meat the red color.
Astaxanthin is chemically relatively stable and if components that promote oxidation are generated, astaxanthin quickly prevents oxidation from progressing.
Salmon returning to their home river for spawning stop eating. As preparation for spawning, their nuptial colors appear on the body surface and the shirozake body starts to change (male snouts curve, females gain black stripes, etc.). In Japanese, this is called the “buna (ブナ)” stage. The meat quality of shirozake in the buna stage drops rapidly. Astaxanthin in the muscle is used to generate the nuptial coloring. Meanwhile, shirozake that wander around their home river during the non-spawning seasons are called “tokishirazu”. The reason the tokishirazu meat is so delicious is likely because the fish’s body is not preparing for spawning and so the meat hasn’t deteriorated.
Salmon climb upriver for spawning. The harsh journey requires a lot of energy, but active oxygen is generated at the same time. When active oxygen is generated in excess, the salmon tires during the journey and is unable to finish climbing the river. This is why they store ample amounts of astaxanthin, which has strong antioxidant effects, in the muscles, and eliminate the active oxygen in their effort to reach the final destination. Salmon that have reached the final destination next transfer the astaxanthin stored in their muscles to the roe. This is to protect the eggs, which are laid in shallow waters that are bombarded with bright ultraviolet rays, from genetic disorders and lipid oxidation.
Incidentally, the antioxidative activity of astaxanthin against active oxygen is said to be 6,000 times that of vitamin C and 800 times that of coenzyme q10, while the antioxidative activity against lipid oxidation is said to be 1,000 times that of vitamin E.
When carotenoid pigment is removed from the muscular substance of salmon, the meat does not appear as a dark red color. The dark red color of the meat of tuna and bonito is from the high content of the pigment myoglobin in the meat. Therefore, these are called red fish. On the other hand, sea bream and flatfish, which do not contain high amounts of myoglobin, are called white fish.
The question of whether salmon is a red fish or a white fish, based on the low content of myoglobin in the muscle, is considered to be a white fish. However, salmon muscle does contain high amounts of creatine and anserine, and also tends to have high levels of histidine. These tendencies are mostly consistent with red fish, and salmon shows aspects common in red fish. This makes it a difficult fish to classify.
However, as a sushi topping, it is classified as a white fish.
So what did you think? To put it simply, these are the only types of salmon used for sushi. Salmon trout and Atlantic salmon are used in things like California rolls, so you have probably eaten them before. But if you see a rare topping such as Masunosuke, Tokishirazu, Keiji, or Sakuramasu in the topping case, don’t hesitate to order. I’m sure you will be moved by the way the Edo-style sushi brings out the maximum umami of the fat, without killing the flavor of the wild salmon. Just for your reference.