The amago or the red-spotted masu salmon (''Oncorhynchus masou macrostomus'') is a

salmonid Salmonidae is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes . It includes salmon (both Atlantic and Pacific species), trout (both ocean-going and landlocked), chars, freshwater whitefis ...

fish

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to western

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

, and a subspecies of the more widespread Northwest Pacific

masu salmon The masu salmon (''Oncorhynchus masou''), also known as masu ( ja, マス, , trout) or in Japan, is a species of salmon belonging to the genus '' Oncorhynchus'', found in the North Pacific along Northeast/East Asian coasts from the Russian Far ...

or cherry salmon (''Oncorhynchus masou''). It is distinguished by the presence of red or

vermilion Vermilion (sometimes vermillion) is a color, color family, and pigment most often made, since ancient history, antiquity until the 19th century, from the powdered mineral cinnabar (a form of mercury sulfide, which is toxic) and its correspondi ...

spots on the body along with black ones, while the nominate form ''O. masou masou'', known as the yamame, only has black ones. The amago is distributed in western Japan, on the Pacific side of the

Honshu , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separ ...

and

Shikoku is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), '' ...

islands, and on the Inland Sea of Japan side of

Kyushu is the third-largest island of Japan's five main islands and the most southerly of the four largest islands ( i.e. excluding Okinawa). In the past, it has been known as , and . The historical regional name referred to Kyushu and its surroun ...

. The subspecies is a subject of

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...

. It can grow up to length. There are both

anadromous Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousan ...

(sea-run) and persistently stream-dwelling populations of the amago. Previously it was considered a subspecies of '' Oncorhynchus rhodurus'', a name that currently only refers to the

Biwa trout The Biwa trout (''Oncorhynchus rhodurus'') is an anadromous salmonid fish of the genus ''Oncorhynchus'', endemic to Lake Biwa in Shiga Prefecture, Japan, but also introduced to Lake Ashi and Lake Chūzenji. While called trout, the fish is most ...

, which has a restricted distribution within the range of the amago.Kato, F. (1991
Life histories of masu and amago salmon (''Oncorhynchus masou and O. rhodurus'')
In: Groot, C., Margolis, L.: Pacific Salmon Life Histories, UBC Press, Vancouver. pp. 449–520.

''O. m. ishikawae'' and the satsukimasu salmon

Varying scientific

nomenclature Nomenclature (, ) is a system of names or terms, or the rules for forming these terms in a particular field of arts or sciences. The principles of naming vary from the relatively informal naming conventions, conventions of everyday speech to the i ...

has been used of the various forms of cherry salmon. The vermilion-spotted amago has been referred to alternatively as ''O. m. ishikawae'' Jordan & McGregor, 1925, in Japanese media.McKay SJ, Nakayama I, Smith MJ, Devlin RH (1998
Relationship between Masu and Amago Salmon Examined through Sequence Analysis of Nuclear and Mitochondrial DNA
''Zoological Science'' 15:971-979 The

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

indicated "''Oncorhychus ishikawai'' " from the

Nagara River The has its source in the city of Gujō, Gifu Prefecture, and its mouth in the city of Kuwana, Mie Prefecture, Japan. Along with the Kiso River and Ibi River, the Nagara River is one of the Kiso Three Rivers of the Nōbi Plain. Previously, ...

only, which is within the amago range, and called it satsukimasu salmon.Kottelat, M. 1996.
''Oncorhynchus ishikawai''2010 IUCN Red List of Threatened Species.
Downloaded on 18 June 2010. "Needs updating" In other sources however the name ''O. m. ishikawae'' has been used of the non-anadromous forms of the widespread, black-spotted yamame, and the

FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.

lists it as a synonym of ''O. masou masou'' that comprises both the anadromous and non-anadromous black-spotted morphs. The

Iwame trout The iwame trout or markless trout is a variety of salmonid fish inhabiting some fresh waters of Japan. It is an intra-specific mutant morph of the masu salmon (''Oncorhynchus masou'') that is characterized by a lack of the lateral spot marks typic ...

is a

recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

unmarked (unspotted)

morph Morph may refer to: Biology * Morph (zoology), a visual or behavioral difference between organisms of distinct populations in a species * Muller's morphs, a classification scheme for genetic mutations * "-morph", a suffix commonly used in tax ...

that occurs in some upstream, non-migrating populations of the amago.Kano, Y., Shimizu, Y., Kondou, K. 2006. Sympatric, simultaneous, and random mating between markless trout (iwame; ''Oncorhynchus iwame'') and red-spotted masu salmon (amago; ''Oncorhynchus masou ishikawae''). Zoological Science 23:71-77. Kano, Y., Kondou, K., Shimizu, Y. 2009. Present status and conservation of the markless forms of stream-resident masu salmon ''Oncorhynchus masou'' (the so-called 'iwame') in Japanese mountain streams. Ichthyological Research 57:78-84

References

External links

Y. Fujioka, My Best Streams: Profile of Amago
��''(personal website)'' {{Taxonbar, from=Q3767959 Oncorhynchus Endemic fauna of Japan Fish of Japan Freshwater fish of Japan Fish of the Pacific Ocean Marine fish of Asia Fish described in 1877 Taxa named by Albert Günther