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 make their way into the sea are 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.
The Japanese name for the blue rainbow trout is Cobaltmasu, derived from its blue body color. Blue rainbow trout is a mutation in the hatchery production of rainbow trout. This fish lacks the middle lobe of the pituitary gland. This resulted in blue body color. This rare genetic glitch has occurred only in rainbow and brown trout. It is said that one blue rainbow trout is born for every ten of thousand rainbow trout. This trait is inherited recessively. It does not reproduce and is susceptible to disease. Therefore, although it has a beautiful body color, it is difficult to produce in large numbers.
The Albino has no pigmentation. Other Albino fish have a white body color, but the Rainbow trout has a yellow body color. Since its first discovery in 1956 at the Fisheries Experiment Station in Nagano Prefecture, Japan, experiments conducted by crossbreeding Albino with other Albino or Albino with ordinary Rainbow trout have shown that it is genetically dominant. Pure descendants of the Albino are now being produced in aquaculture farms throughout Japan.
Albino is rarely found in the normal production of Rainbow trout in aquaculture farms. Albino is a mutation of the Rainbow trout that lacks tyrosinase (An enzyme that breaks down tyrosine, a type of amino acid, to produce melanin). This prevents the production of melanin, a black pigment, and causes the trout to turn yellow. The yellowish coloration is thought to be due to the other pigments that remain after the melanin-black pigment is gone.
Normal Albino is genetically recessive, so if both parents are not Albino, their offspring will not be Albino. However, Albino rainbow trout is dominant, so if either male or female parent is an Albino, their offspring will be born as an Albino.
Neither the albino rainbow trout nor the blue rainbow trout is a protective color, so if it were to occur in nature, it would have little chance of surviving due to bird damage.
Albino rainbow trout has little edible value but is released for recreational fishing because of its scarcity. In fish farms, it is sometimes used as a visible indicator of growth. There may be some differences in taste, smell, and texture, but these are within the range of individual differences. And Sushi chefs do not use Albino rainbow trout for sushi.
The Iwana group is divided into four subspecies, with body color and spots varying from region to region. The Ezo Iwana (Salvelinus leucomaenis (Pallas, 1814)) is distributed in Yamagata Prefecture, Chiba Prefecture and northward, Hokkaido to Kamchatka, Sakhalin, and elsewhere. The Yamato Iwana (Salvelinus leucomaenis japonicus (Oshima, 1938)) is distributed along the Pacific coast of Honshu west of the Sagami River in Kanagawa Prefecture, the Kii Peninsula, and the rivers flowing into Lake Biwa. The Nikko Iwana (Salvelinus leucomaenis pluvius (Hilgendorf, 1876)) is distributed throughout Honshu north of the Fuji River in Yamanashi Prefecture and the Hino River in Tottori Prefecture. The Gogi (Salvelinus leucomaenis imbrius (Jordan and McGregor,1925)) is distributed in the Chugoku region west of the Yoshii River in Okayama Prefecture and the Ibo River in Tottori Prefecture. Although all are land-locked, the Ezo Iwana has a descending sea-run type, the Amemasu (アメマス). However, there is one species.
The White-spotted Char (Iwana) is characterized by its low body height, long and slender body, fine scales, whitish spots on the body that are lighter than the body’s natural color, and white anterior margin of the pectoral and anal fins. It lives in the uppermost reaches of mountain streams and is separated from Yamame and Amago, which live in the same streams.
What does White spotted Char (Iwana) sushi taste like?
Because Iwana is in the salmon family, they descend to the sea or lakes during their growth period and migrate up rivers as adults. Most of the rivers in Japan are among the world’s steepest, with short lengths, elevation differences, and fast currents. Therefore, it is thought that Iwana has the strength and muscles to withstand the rapid river currents and become tighter. The best ways to cook tight-fleshed Iwana are deep-fried, grilled, and sashimi, which takes advantage of the fish’s firmness when eaten. Arctic char, a close relative, is highly prized in French cuisine, and lives in Lake Leman and Lake Annecy, and is actively farmed in many areas.
Even Iwana pressed sushi is quite rare, but if you want to eat nigiri sushi, you will have to go to a restaurant adjacent to an aquaculture farm in Nagano or Toyama. It may look like Shiromi, but it has the flavor of salmon itself. However, the meat and flavor are somewhat inferior to those of Yamame and Amago.
Sakhalin taimen is distributed only in the southern Kuril Islands, Sakhalin, Primorsky Territory, and Hokkaido. It used to be distributed in Lake Ogawara, Aomori Prefecture, but has already become extinct. In Hokkaido, it inhabits gently meandering rivers in the Konsen Plain, Sarufutsu Plain, and Sarobetsu Plain.
Reaching a maximum height of 2 m, it is the largest freshwater fish distributed in Japan. Its Japanese name is Itou and its scientific name is Parahucho perryi (Brevoort, 1856).
The body color is light purple or light green on the back side and silvery white on the belly side. Unlike other salmonids, Sakhalin taimen lay their eggs in the spring and do not die, but instead lay them over and over again for many years. Females are usually larger than males, sometimes twice as large as males. The “魚鬼” Chinese character combines “魚” (fish) and “鬼” (devil). As the Chinese characters suggest, it is known for its ferocious nature.
It is also farmed in Aomori and Niigata, but because it takes 5~6 years to grow to 50 cm in length, it is not commercially available and is used at hotels and other places as a regional specialty.
What does Sakhalin taimen (Itou) sushi taste like?
Its flesh is not peculiar and is a slightly pale orange color. The texture is tender but strangely does not feel tender and melting. It is rarely served at sushi restaurants in Tokyo, but it is probably farm-raised Sakhalin taimen. Whether or not it is a natural product, it is a very rare topping, so if you find it, you should definitely try it.
In Europe, the word “Trout” often refers to Brown trout. It has been transplanted to many parts of the world as an angling target fish.
Since the 1860s, it has been transplanted to all parts of the world and has become established in natural waters. It appears to have been transplanted to Japan in the 1930s via the U.S. mixed with Brook trout eggs, and natural reproduction has been confirmed in Lake Chuzenji, Lake Ashi, and the upper reaches of the Katsura River.
Body shape is similar to Rainbow trout, etc. The body color is grayish blue with relatively large black spots on the dorsal surface of the body and near the base of the dorsal fin, and whitish-orange spots below the lateral line. 1-5 years in freshwater, then become smolt and descend to the sea, spending 6 months to 5 years in the ocean. The descending type is also called Seatrout. Some spend their entire lives in freshwater areas such as rivers and lakes. It reaches a maximum length of 0.7 m.
What does Brown trout sushi taste like?
Brown trout is said to have less fat and a lighter flavor than rainbow trout, and when eaten as sashimi, it should be frozen completely before eating, since it is a freshwater fish, it is possible that parasites may be hidden in it. It also has a fishy odor unique to river fish, so it is necessary to quickly remove the blood. However, we have never heard of a sushi restaurant serving brown trout nigiri. Brown trout and Rainbow trout hybrids are sold as Shinshu-salmon (信州サーモン), and their market price is over 2,000 yen per kilogram. Shinshu-salmon nigiri is commonly eaten in Nagano and other places in Japan.
In Europe, where it originated, it is a high-grade fish that is delicious to eat. It is farmed mainly in France and Austria for eating purposes. However, compared to Rainbow trout, it grows more slowly and is more difficult to farm, so there are only a few companies that provide it. Hence, it is expensive. The main way to eat trout is to cook it. Incidentally, Schubert’s song “The Trout” was inspired by the brown trout.
Toro was originally used for bluefin tuna (and later for all tuna), but Beni toro was probably the first example of the term being applied to a fish other than tuna.
Around 1970, a major fishery company called Kyokuyo (極洋) gave the name to a sashimi product of fatty Benizake (sockeye salmon; Oncorhynchus nerka) caught in the North Sea, which had not yet entered the spawning migration stage.
It took many years from application to approval due to various problems, but Beni toro became a legitimately registered trademark in 1987. The registration number is 1991889.
Biwa trout is a species of fish native to Lake Biwa, but is also found in Lake Kizaki, Lake Chuzenji, Lake Ashi, and other lakes through transplantation. The Japanese name for Biwa trout is Biwa masu (琵琶鱒). As indicated by its scientific name, Oncorhynchus masou subsp., it is considered to be a subspecies of Satsukimasu (Red-spotted masu trout). It reaches up to 60 cm, and the spots on the body are pale orange and disappear with growth. The adult one has a silver colored body.
It has also been farmed in Japan for a long time. There is even a famous Biwa trout farm near Lake Biwa in Shiga Prefecture that has been in operation since 1878.
An interesting fact about Biwa trout is that it is a landlocked variety of Pacific Salmon while being anadromous as it moves between the freshwater lake Biwa and surrounding rivers according to the water temperature as part of its life cycle.
What does Biwa trout sushi taste like?
The natural Biwa trout season is from June to early September. At this time of year, it has no peculiar flavor and has large amounts of fat with refined sweetness. When you put it in your mouth, only the delicious flavor of the fat spreads out as if it were melting softly. The rich flavor of trout can also be fully enjoyed as a sushi topping.
Sushi restaurants in Shiga prefecture, such as Kyogoku-zushi, serve Biwa masu nigiri sushi during the summer months. Ordinary Ikura is red in color because salmon go down to the sea and feed on crabs and shrimps, taking in red pigment. Biwa masu, on the other hand, grows only in lakes, so it does not take in any pigment and its eggs remain golden. Kyogoku-zushi also offers this Golden Ikura sushi. Both are rarely seen at sushi restaurants in Tokyo.
In Japan, salmon roe that has been separated from the ovarian membrane and then salted is called ikura. At sushi restaurants, this is also marinated in broth that includes soy sauce, mirin and sake. This is called ikura marinated in soy sauce, or simply ikura. Worldwide, caviar is considered to be of more value than ikura. Therefore, in an attempt to improve the impression of soy sauce-marinated ikura, it is sometimes called ‘salmon caviar’. This is behavior especially seen among manufacturers selling soy sauce-marinated ikura.
You probably already know this, but “toro tuna” is not the name of a type of fish. “Toro” is the name of a fatty part of the tuna. The fat content and attributes of the belly side of the tuna are completely different from that of the dorsal side. Toro is the name of the part near the head, mostly on the belly side.
In the same way, there is no fish called “toro salmon”. Just like tuna, “toro” refers to the fatty part on the belly side of the salmon. It is also called “harasu” in Japanese. This is how the word is used at some scrupulous sushi restaurants. This description of “toro salmon” is correct.
Most salmon used at conveyor belt sushi restaurants is either trout salmon or Atlantic salmon. The reason this salmon can be served at the cheap price of US $1 or $2 per plate (2 pieces of sushi) is that these particular fish are all farmed and are available in bulk quantities from overseas. This salmon is mainly imported to Japan from Norway, Chile, Scotland and Canada.
Actually, the popular “toro salmon” topping is made from these imported items and the fat content is three times that of wild salmon. Feeding farmed salmon plenty of solid compounded feed that is high in protein and high in fat, turns the entire body to toro.
Salmon, which are born in freshwater and migrate downstream to the sea are called “sea-run fish” and they may be farmed in either seawater or freshwater. Trout salmon is “former” rainbow trout that was raised in a fish cage in the sea. In the wild, the sea-run rainbow trout grows up to 1 m in length, its body turns silver and the meat takes on a red color. The wild version of these are called “steelhead” and fetch a high market price, so they are not used in conveyor belt sushi restaurants.
Just like other aquaculture, salmon farming faces some difficult issues. It may surprise you that salmon is actually a white fish, originally. In the wild, the salmon meat gets a red color from feeding on crustaceans such as crab and shrimp that contain the red pigment astaxanthin. However, in the fish cages where the salmon are surrounded by nets, the food chain is also restricted. The compound feed would be plenty if the goal was only to raise bigger fish, but that results in a grey color or light yellow meat that doesn’t even resemble the salmon pink (orange?) that everyone wants and they don’t sell.
Therefore, when making the solid compounded feed, artificial coloring is mixed in. One of the colorings is called canthaxanthin. This is a synthetic chemical derived from petroleum. There is a color chart with 10 different, detailed levels of red coloring and buyers can even indicate which color they would like and the farmers can achieve it. It’s kind of like an industrial product that is being manufactured. Japanese people prefer a dark red color for salmon in the same way they do for tuna, so the coloring for Japan’s market is adapted to that.
When light is shone on wild salmon, the red coloring looks faded, but the light makes farmed salmon that have been fed coloring, look brighter. Artificial coloring is a necessity in farmed salmon and this is true for the trout salmon and Atlantic salmon that are used as the ingredients for toro salmon as well. All of the farmed salmon in circulation have been colored in this way, so much so that it wouldn’t be surprising if the insides of their stomachs were stained red. The flamingos at zoos also get their beautiful pink feathers from these chemicals.
Trout salmon is rainbow trout that has been farmed in the sea. On the other hand, rainbow trout farmed in freshwater is called Donaldson trout. Of all the large rainbow trout gathered at each location, those with small heads and fat bodies were selected and bred over many years to create this type. The objective of choosing a small head is to make more meat. They are characterized by their fast growth and while normal, farmed rainbow trout grow to about 30 to 40 cm, Donaldson trout grow up to nearly 1 m. The name is taken from the American who developed this variant.
The Donaldson trout is farmed throughout Japan and is used as toro salmon and aburi salmon at conveyor belt sushi restaurants. Since they are supplied directly to the processor (of the salmon) from the farmer without going through the market, they may be sold cheaper than the import price. Just like the imported salmon, this farmed salmon is also fed artificial coloring. There are also already new variants improved from the Donaldson trout being bred. Trout made from breeding Donaldson trout females and steelhead males are called Donaldson steelhead, for instance. They grow even faster.
Ample use of the latest biotechnology has been made in salmon farming and some of these technologies include creating young fish without functioning reproductive organs, “triploids” which means increasing the size of the fish up to triple and “all female populations” where males are converted into females. The triploid fish grow large in correlation to the lack of energy exertion. The objective of all-female populations is to get more masuko (ovaries). Masuko is used for the ikura (salmon roe) at conveyor belt sushi, and since the fish that the roe is harvested from have an inferior flavor, they are used for aburi salmon. Now, there are even triploid, all-female farm populations. No wonder the restaurants can serve a plate (2 pieces) of salmon sushi for US $1.
The simple phrase, “toro salmon” contains so much meaning.
When you put food in your mouth, the components that are dissolved by your saliva are called extract components. Extract components include mainly free amino acid and inosinic acid as well as organic-based components such as adenosine triphosphate-related substances, creatine and trimethylamine oxide. Extract components are important components that make up the flavor of foods.
When we looked up the extract component composition of the muscle of chum salmon, sockeye salmon, coho salmon and king salmon, which are all types of salmon, the component composition of chum salmon, sockeye salmon, coho salmon and king salmon are all similar.
The taste of fish is much lighter in comparison to the muscle meat of shrimp, crab and squid types of seafood. By combining extract components, shrimp, crab and squid flavors can be reproduced, but the relationship between the flavor extract components and fat in fish meat plays an important role in taste. The fat of fish gives it a rich flavor, illustrated by the fact that compared to the back meat of fish, the taste of the belly meat, which is abundant in fat to protect the organs, has a richer flavor.
The difference between the muscle of salmon and tuna is that salmon tends to have a lower inosinic acid content. Although not unique to salmon, the delicious taste of fish meat is related to the amount of inosinic acid and the amount of fat. Umami is mainly made up of inosinic acid is strongly related to fat and in case of inosinic acid content is high, it doesn’t feel “fatty” even with high-fat content. Instead, the fat makes it more pleasant and delicious.
On the other hand, when the inosinic acid content is low, a high-fat content doesn’t really translate into a pleasant taste. In the case of farmed fish, where high importance is attached to the weight of the fish when it is shipped, even if the fat content is high, if the inosinic acid level is low, then the fatty aspect does not translate into deliciousness, which is likely what leads to the opinion that the flavor of farmed fish is inferior to wild fish.
In the case of salmon variations, the inosinic acid content is low compared to tuna variations, and generally, the optimal amount of fat for delicious salmon is 4 to 6%. With tuna, the general idea is, the more fat, the more delicious, but this is not true for the taste of salmon.
Fat on animals that live above ground hardens when refrigerated. This creates an unpleasant waxy texture when eaten. However, as fish live in the frigid ocean waters, their fat doesn’t harden, even when stored at about -18℃. The most appealing aspect of salmon is thought to be that it goes well with shari (vinegared rice). The meat is soft and the fat has a low melting point, so it blends easily with shari and emits a sweetness when you bite. This is a sensation you won’t find with much other fish.
Natural fish are part of the food chain and have concentrations of harmful substances. Since 2000 the amount of mercury found in fish has become an issue. The American Natural Resources Defense Council has said tuna is a fish that should be avoided if pregnant or planning to get pregnant. A more recent problem is the large amounts of micro plastics found in fish meat. This shocking phenomenon will likely be reported by research organizations at some point in time. If it does reach that extreme, then it will be better to avoid the danger of eating fish.
Before continuing, please read the exclusive articles in major media and research papers.
The red tide (algal bloom) frequently occurs off the coast of Chile and it is resulting a large amount of salmon deaths. In 2015 27 million salmon died in a mass event, of which 25,000 tons were powdered and then fed to the healthy salmon (according to the UK’s Guardian reports).
Chilean fish farmers are using large quantities of antibiotics to control fish diseases. They use 500-700 times more antibiotics than Norway does. 80% of antibiotics imported into Chile are intended for the fish farming industry. Faced with the risk of bacteria resistant to antibiotics emerging, as highlighted by the World Health Organization (WHO), the Chilean National Fish Service is calling for a reduction in the use of antibiotics. (Extract from Le Monde diplomatique Japanese edition）
The bright color of salmon is something that you would never see a long time ago, but is now commonplace. It is likely due to the Canthaxanthin pigment mixed into their feed. Salmon is in fact a white fish. The salmon that is caught in Japan is called “Shirozake” or white salmon and its flesh is not a pink before it goes out to sea. Once it is out at sea, it swims around consuming small plankton and crustaceans such as shrimp and krill. Its body then takes on a pink color due to the intake of natural coloring of Astaxanthin. This Astaxanthin has antioxidant effects and it is noted for playing a part in relieving fatigue and preventing aging. However, the synthetic pigmentation that creates the salmon pink does not provide the same health benefits.
The US Food and Drug Administration (FDA) gave approval for genetically modified salmon on November 19th, 2015. This genetically modified salmon is called “AquAdvantage salmon.” It grows faster than regular salmon and its body length is almost double. There are groups opposing the sale of this salmon, including US citizen group Center for Food Safety, the Japanese Seikatsu Club, and the European parliament. There are still many unknowns regarding the safety of this type of fish for human consumption, and a number of issues are still being debated. The discussion has been featured in “Nature” magazine.
Endosulfan is a type of organochlorine compound, like Dichloro Diphenyl Trichloroethane, Dicofol, Heptachlor, Chlordane, Mirex, Pentachlorophenol, and is known to be extremely toxic, but the EU approved Endosulfan for use as feed in Norway’s salmon farming industry in 2013.
Researchers analyzed the risk-benefit ratio based on levels of contaminants like dioxins, PCBs and chlorinated pesticides versus omega-3 fatty acid levels. While farmed salmon is higher in omega-3s, it is also significantly higher in these toxins (about 10 times) which can produce birth defects, lower IQ, and cause cancer. They determined the following based on origin of the salmon: “consumers should not eat farmed fish from Scotland, Norway and eastern Canada more than three times a year; farmed fish from Maine, western Canada and Washington state no more than three to six times a year; and farmed fish from Chile no more than about six times a year. Wild chum salmon can be consumed safely as often as once a week, pink salmon, Sockeye and Coho about twice a month and Chinook just under once a month.” (Extract from The Journal of Nutrition)
There is a saying, where there’s smoke, there’s fire. It is unlikely that big media outlet and research organizations would join forces to circulate incorrect information. Furthermore, this is not a problem that only affects certain countries like Chile or Norway. It should be considered as a problem for the entire farmed salmon industry.
On the other side of the debate, there are articles such as the following. Norway’s NIFES (National Institute of Nutrition and Seafood Research) sampled 13,180 farmed fish (of which 90% were salmon) and monitored them for medicines, substances that are prohibited by law, and other pollutants, publishing their report on August 17th 2015. In their latest report, it concluded that Norwegian farmed fish were safe and that illegal and undesirable substances were not observed to exceed standards. Further, it seems that they have confirmed decrease in most of the pollutants analyzed in the investigation.
But the fact is that, according to these articles, while the chemicals did not exceed standard values, they were certainly found to be present in farmed salmon. The other extreme would be to say that eating natural un-farmed salmon will not expose you to the potential risks from these types of chemicals.
However, that’s not really practical. The global production of farmed salmon is 2.5 million tons a year, approximately three times the 800,000 tons of naturally fished salmon. No matter what way you slice it, the option of farmed salmon isn’t going away anytime soon.
The Japanese were not in the habit of eating salmon raw. Salmon was not a traditional topping in Edo-style sushi. The reason for this is that the existence of parasites has been well-known since long ago and there was no way to prepare the salmon raw.
According to the Ministry of Health, Labour and Welfare, salmon must be frozen at -20℃ for at least 24 hours in order to completely kill all parasites. Salmon served at sushi restaurants must be stored frozen and then thawed before serving.
The type of salmon (sake) you find in Japan is Chum salmon. However, most of the salmon served raw at sushi restaurants is Atlantic salmon. This is a popular topping throughout the world due to the high-fat content and smooth texture achieved by sea farming in places like Norway and Chile. The fish are strictly managed from water quality to the effects on the environment, so there are very few issues with parasites and the salmon can be eaten raw. However, the fact remains that the fish are administered a number of chemicals due to concern of the spread of disease-causing germs in the farms.
Even when salmon roe and sea urchin first started to be used as toppings, most sushi chefs said that these didn’t count as Nigirizushi and refused to use them. However the favorable reputation of sea urchin sushi in Ginza won out, it started to be used by more chefs and eventually became one of the major dishes.
The fifth-generation sushi chef at one long-standing shop says, “If it’s what the customers want, then salmon may also be rolled as Nigirizushi in the near future.” It may even become part of the standard menu.
At a pre-Edo sushi shop that features Hokkaido toppings, they are actually serving ultra-high grade salmon such as Keiji* and Tokishirazu**.
*Keiji are 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%.
**Tokishirazu are salmon swimming upstream at 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”