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, Spring salmon, Blackmouth or Tyee salmon)
Scientific name: Oncorhynchus tshawytscha (Walbaum)
The standard Japanese name is 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 and northern Japan Sea.
The King salmon evolved in very long and raging rivers in the Northern Hemisphere. Its body has developed thick and sound so that it can complete the magnificent journey, which is hundreds of kilometers long. It has more fat than other salmon, and the longer the trip to its birthplace, the more fat it stores. Due to the unique environment where it evolved, King salmon is the rarest of salmon and accounts for less than 0.1% of all salmon worldwide. 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)
The standard Japanese name is Shirozake (Sake). It is called Shirozake (‘shiro’ means white and ‘zake’ means salmon in Japanese) because it has the lightest shade of red of all Salmon. 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 Chum salmon that come to the Tohoku and Hokkaido coastal regions during the spawning season, which spans from September to November. As it returns to the river where it hatched in Hokkaido and Honshu in the autumn, mature Chum salmon about to spawn is called Akiazake (autumn salmon) or Akiaji (autumn flavor). Of these, Akiazake with shiny, silver scales known as Ginke (silver hair) fetches a high market price. It has a lower level of maturity than Akiazake (1 to 2 months prior to spawning) and it is fished in fixed fishing nets along the coast.
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 its 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 caught in the sea before swimming upstreat to spawn is called Ginke and both males and females are a shiny silver color. The Ginke also has a relatively gentle face. Migrating Sakuramasu (Cherry salmon) and Masunosuke (King salmon) also have the same sort of silver body. 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.
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. One reason for this is that Akizake has around 10% fat, but it stops feeding a few months before swimming upstream in rivers, so this fat percentage decreases as it approaches the spawning site.
The fully matured roe of the ‘buna’ rank of Chum salmon has 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. It generally goes for around $2 to $4 per kilogram.
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 start 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. At its cheapest, the body goes for 50 cents per kilogram after the roe has been harvested.
Pink salmon (Also called Humpback salmon)
Scientific name: Oncorhynchus gorbuscha (Walbaum)
The standard Japanese name is Karafutomasu. In some Hokkaido production areas, it is called by the brand name, Okhotsk Salmon. These fish are distributed widely from California to Alaska, the Korean peninsula and Hokkaido.
It has evolved over millions of years so that it can live in small rivers that flow into the North Pacific Ocean. The fry feed very little in the river and instead swim downstream to the sea immediately. The period until maturation is like clockwork, and the young fish always return two years after hatching. There is no landlocked variety and this species spends a very short time in freshwater and don’t tend to follow mother‐river migration as strictly. The Pink salmon takes a short trip up a shallow river, returning to its birthplace to spawn. The fact that the upstream distance the Pink salmon travels is short, is apparent in the meat texture. The meat contains very little in terms of fat reserves and lacks the muscle development found in salmon that must travel upstream long distances. Due to its low fat content and lack of muscle development, Pink salmon also lacks the rich, deep flavor–umami–contained in premium salmon found in the Atlantic and Pacific oceans.
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)
The standard Japanese name is Ginzake. Wild Silver salmon inhabit the Northern Pacific ocean regions and don’t swim upstream in Japan’s rivers.
After the hatched fry spends one year in the river, it then lives for two or three years in the sea before returning to the river. Its main food source in the rivers is insects, but like the King salmon, once it starts migrating it becomes ichthyophagous and preys on herring and sardines as well as squid. It grows remarkably quickly, reaching about 10 cm when it swims downstream to the sea, and then grows to 40 cm at 2 years and 60 cm at 3 years old while living in the ocean. The color of the meat is an orangish-pink, darker in color than Pink salmon and follows King salmon and Red salmon in red shade.
Most of the Silver salmon currently in circulation has a stable supply from aquaculture. Sea-farmed Silver salmon is fed high volumes of food and grows many times faster than wild Silver salmon. It grows to around 3 to 4 kg in about a year. The taste is good and the size allows for large fillets, so it is used for salmon steak, smoked salmon and salted salmon. They are primarily used for processing and the price is a bit lower.
In Japan, around 100,000 tons of farmed Silver salmon is imported from Chile every year. This farmed version has double the fatty meat of wild Silver salmon. It is especially good for grilling and most of the salmon used in rice balls and bento boxes sold at convenience stores in Japan came from Chile.
On the other hand, Japan farms 15,000 tons of Silver salmon annually and 90% of that is raised in Miyagi prefecture. Special care is taken for the food this salmon is fed, there is no unpleasant odor, the fat distribution is perfect and it has a texture that melts in your mouth. This Silver salmon is managed thoroughly to create the best quality and it is used for Nigiri sushi and sashimi.
Red salmon (Also called Sockeye salmon or Kockanee salmon)
Scientific name: Oncorhynchus nerka (Walbaum)
The standard Japanese name is Benizake. Red salmon are distributed throughout the northern Pacific Ocean, Okhotsk Sea and the Bering Sea.
The most unique salmon evolution is that of the Red salmon. The way it evolved not only resulted in the indisputably richest flavor of all salmon but also the powerful red color. Before most Red salmon descends into the ocean, it spends its first two years in a freshwater lake where it eats tiny shrimp and crabs as well as zooplankton. Afterward, it continues the same diet even after maturing and going out to sea. As it consumes high amounts of the carotenoid pigment, Astaxanthin, it has a high carotenoid pigment content compared to salmon that eats small fish, squid and jellyfish. Red salmon meat has a bright and highly concentrated color and is dense because of this diet.
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. In Alaska, where aquaculture is completely banned, wild-caught Red salmon and Silver salmon are frozen, the parasites are killed, and then they are used for sashimi and sushi.
Atlantic salmon (Also called Black salmon)
Scientific name: Salmo salar Linnaeus
The standard Japanese name is Taiseiyosake. Natural Atlantic salmon is widely distributed around the North Atlantic and its tributaries. It has been transplanted to many countries since 1860 and lives naturally in the waters of Finland, New Zealand, Australia, Argentina and Chile. It can grow to 120 cm and weigh 40 kg. Atlantic salmon goes by a number of aliases depending on when and where it is fished.
Meanwhile, it is farmed in salt water for food throughout the world. 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.
Atlantic salmon farmed in the Fjords of Norway is branded as Norway salmon, which can be called a pioneer for Farmed Atlantic salmon. Once it leaves Norway’s aquaculture farm, it is processed into fillets or dress at a processing plant adjacent to the port, then amazingly makes it to the shelves at Toyosu Market in 36 hours. It is important to note that genetic modification of farmed salmon is forbidden in Norway and this is strictly monitored through regular on-site inspections. In order to make this differentiation in the Japanese market, it is sold as Aurora salmon with an emphasis on its premium flavor. Some long-established sushi restaurants may also start using Atlantic salmon for Nigiri sushi in the future. Incidentally, other brands of Atlantic salmon include Scottish salmon, Canadian salmon, Faroe salmon and Tasmanian salmon, among others.
Rainbow trout (Also called Steelhead)
Scientific name: Oncorhynchus mykiss (Walbaum)
Rainbow trout is found in North America from Alaska to the northwestern part of Mexico and in the Kamchatka Peninsula. It is named for the wide vertical shiny, rainbow stripe on the side of its body. From the end of the 19th century, it transplanted to nearly all areas in North America, South America, Australia, New Zealand, Japan, Taiwan and Europe. It grows to lengths of 40 to 60 cm. The standard Japanese name is Nijimasu.
It was imported from the United States into Lake Chuzenji in Japan in 1877, and it is now a general and central presence as farmed salmon. It is primarily farmed in freshwater. Tests for saltwater farming also began in 1971, but most of those activities were abandoned. However, this has been reviewed in recent years in an aim to build a new pillar of revenue to supplement chum salmon due to continued poor catches. Meanwhile, saltwater farmed Rainbow trout is already being distributed. An example can be seen in Miyako Trout salmon from Miyako City, Iwate Prefecture.
Salmon that is small and always stays in streams is called Rainbow trout. On the other hand, there is also a group that descends into the sea, grows there, and then goes upriver to spawn. The body is silver in color while the head shines like steel, giving it the name Tetsu in Japanese and Steelhead in English. It normally grows to around 75 cm and weighs about 4.5 kg, but it may grow longer than 1 meter in length and reach 15 kg. Steelhead spawns in the same way as salmon, and the hatched fry live in the river, exactly like Rainbow trout. If Steelhead and Rainbow trout were mixed together at this point in their development, it is impossible to distinguish between young Steelhead and land-locked Rainbow trout. It’s not until about two years later that they can finally be told apart. Rainbow trout start to mature at this time while those planning to descend into the sea do not. The two names show that they were thought to be different fish.
Rainbow trout can be purchased at Toyosu Market, but it is generally used for dishes other than sushi. I have no information on whether Steelhead is used in sushi restaurants or not, but Nijimasu and Steelhead don’t sound like very delicious sushi.
Nutrition and Effects of Rainbow trout
Rainbow trout is a healthy fish. It is low in calories and high in protein with a good balance of vitamins, minerals and unsaturated fatty acids. In particular, it has 6㎍ of vitamin B12 per 100 grams, a vitamin that is only found in animal fiber and foods like natto. The daily intake per adult recommended by Japan’s Ministry of Health, Labour and Welfare is at least 2.4 μg, so Rainbow trout provides about 2.5 times that. Blueback fish are said to have the highest content of DHA, which is found in the fat of fish. It is a little-known fact that Rainbow trout actually has about 552 mg DHA, which is 1.5 times the DHA of Aji, a blueback fish. It also has a nice balance of calcium, phosphorus, zinc, etc.
Rainbow trout has one of the more ample appetites of salmon and it is omnivorous. Therefore, it makes sense that it grows at a faster rate than other salmon and is the most suitable for farming. Furthermore, this growth speeds up even more when raised in the sea, increasing its size by about five times over six months. It is called both Trout salmon and Salmon trout. These names aren’t actually indicative of the species of the fish but is the distribution name for Rainbow trout farmed in sea water.
As aquaculture grows, the farmed fish undergo selective breeding. For example, of all the large Rainbow trout, those with small heads and fat bodies were selected and bred over many years to create the Donaldson trout. It is characterized by its growth to large sizes. While a normal, farmed Rainbow trout grows to about 30 to 40 cm, the Donaldson trout grows up to 60 to 70 cm, about the same as a chum salmon. A hybrid made from breeding a female Donaldson trout and a male Steelhead is called the Donaldson steelhead, which grows even faster.
Generally, it is distributed frozen, as fillets. This is the type that is just called, “salmon” at conveyor belt sushi restaurants and grocery stores as take-out sushi. Production is stable, they are cheap and taste good. They are characterized by not having the strong odor that salmon is known to have.
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. Masunousuke (King salmon) especially prefers cold waters compared to other salmon. It lives at a high latitude and mainly habits the northern Pacific Ocean from the Kamchatka Peninsula to Alaska. On rare occasions it will even migrate to the seas surrounding Japan and although it can be fished mainly in Hokkaido, catches are extremely rare. Therefore, it sells for high prices. There are no rivers in Japan that serve as permanent spawning grounds for this salmon. The peak season is from spring to early summer. The image on the right is Masunosuke Nigiri 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”. What it is called differs depending on the region. In Hokkaido, it is called Tokishirazu or Tokizake. In the Sanriku region, it is called Oome or Oomemasu.
It has a higher fat content than Ginke and Mejika and sells for more than $20 per kilogram. The premium fat envelopes the sushi rice without a hint of the odor salmon is known for. Also, Hokkaido sushi restaurants sometimes venture to make fresh Tokishirazu into Zuke as a method to fully bring out its umami. Even when it comes to high-end sushi restaurants in Ginza and Nishiazabu, there are very few that serve Tokishirazu Nigiri sushi. The most likely restaurant you will find Tokishirazu Nigiri is Sushi Sho in Yotsuya, and the several small restaurants opened by chefs who apprenticed there. The image on the right is Tokishirazu Nigiri 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. No more than a few hundred can be caught each year in the Shiretoko area of Hokkaido. 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.
There are even fewer restaurants that serve Keiji Nigiri sushi than there are that serve Tokishirazu. It is sometimes available at Sushi Kutani in Ginza, which specializes in Hokkaido sushi toppings, but it is reserved for regular customers and not something that a new customer will be served on their first visit. Put in terms of tuna, the taste is more like Mejimaguro Harasu, rather than Otoro. Surprisingly, the high-fat content isn’t very noticeable and the meat is smooth with an incredible texture. The fat that tells of the fish’s youthfulness, harmonizes well with the sushi rice. The image on the right is Keiji Nigiri 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. It is also known as Masu salmon or Cherry salmon. It is found in the Chishima Islands, Sakhalin, the Southern part of the Kamchatka Peninsula, the Sea of Okhotsk, and the Korean Peninsula, which is the lowest distribution area of any type of Salmon.
They are caught in the rivers near the estuaries when swimming upstream. Normally they spend a year and a half in the rivers and 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.
Incidentally, in Japan, Sakuramasu that don’t eat for the short time after entering the river are said to have lost the odor of the feed and have a more refined taste than Sakuramasu caught in fixed fishing nets right before setting off to swim upstream.
And, the Biwa trout, which is a subspecies of the Cherry salmon only found in Lake Biwa, lives in freshwater, and thus never causes food poisoning by Anisakis. This makes it suitable for sashimi and sushi, but it is frozen before it is used at sushi restaurants, just in case. This is because it does not lose any freshness or flavor even when frozen. The image on the right is sakuramasu sushi.
Chum salmon that climbs the rivers of Niigata and Yamagata, and is caught in Hokkaido during its migration, is called Mejika. It gets this name from the fact that the distance between the eyes and snout is very short. It also doesn’t have the characteristic hooked snout (kype) unique to spawning season and the silver scales peel off easily and have a black luster. It is caught from October to November, which is the end of the fishing season for Akiazake. It has a lower maturity stage than Ginke and also has a nice fat distribution due to storing nutrients in preparation for swimming upstream. It is often said that males get fatty on the belly side, while females get fatty on the dorsal side. This is a rare salmon as it accounts for only 1 in 1,000 of salmon caught in fixed nets and it goes for $10 to $20 per kilogram.
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.