Salmonidae is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

that constitutes the only currently extant family in the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Salmoniformes . It includes

salmon Salmon () is the common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of ...

(both Atlantic and Pacific species),

trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', '' Salmo'' and '' Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-sa ...

(both ocean-going and landlocked),

chars Chars () is a commune in the Val-d'Oise department in Île-de-France in northern France. It is located in the . Education Chars has a single preschool, école maternelle des Tournesols, and a single elementary school, ecole elementaire de chars. ...

freshwater whitefish The freshwater whitefish are fishes of the subfamily Coregoninae, which contains whitefishes (both freshwater and anadromous) and ciscoes, and is one of three subfamilies in the salmon family Salmonidae. Apart from the subfamily Coregoninae, ...

es, graylings, taimens and

lenok Lenoks, otherwise known as Asiatic trout or Manchurian trout,James Card: Fly fishing in South Korea.' Retrieved 22 June 2015. are salmonid fish of the genus ''Brachymystax'', native to rivers and lakes in Mongolia, Kazakhstan, wider Siberia (incl ...

s, which are collectively known as the salmonids ("salmon-like fish"). The Atlantic salmon (''Salmo salar''), whose

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...

name became that of its

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

Salmo ''Salmo'' is a genus of ray-finned fish from the family Salmonidae. The single ''Salmo'' species naturally found in the Atlantic North America is the Atlantic salmon, whereas the salmon and trout of the Pacific basin belong to another genus, '' ...

'', is also the source of the family and order names. Salmonids have a relatively primitive appearance among the

teleost Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tel ...

fish, with the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two e ...

s being placed far back, and an

adipose fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...

towards the rear of the back. They have slender bodies, with rounded

scale Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number ...

s and forked tails, and their

mouth In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on t ...

s contain a single row of sharp teeth. Although the smallest species is just long as an adult, most are much larger, with the largest reaching . All salmonids spawn in

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...

of upper reaches of

river A river is a natural flowing watercourse, usually freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the ...

s and

creek A creek in North America and elsewhere, such as Australia, is a stream that is usually smaller than a river. In the British Isles it is a small tidal inlet. Creek may also refer to: People * Creek people, also known as Muscogee, Native Americans ...

s, but in many cases, the fish spend most of their adult lives at

sea The sea, connected as the world ocean or simply the ocean, is the body of salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote second-order sections of the sea, such as the Mediterranean Sea, ...

or in

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environme ...

, returning to the rivers only to reproduce. This lifecycle is described as

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 ...

. Salmonids are

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

s of the middle

food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), d ...

, feeding on small

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

aquatic insect Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some ''diving'' insects, such as predatory diving beetles, can hunt for food underwater where land-living insects ...

s and smaller fish, and in turn being preyed upon by larger predators. Many species of salmonids are thus considered

keystone organism A keystone species is a species which has a disproportionately large effect on its natural environment relative to its abundance, a concept introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in maintaini ...

s important for both

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does in ...

and

terrestrial ecosystem Terrestrial ecosystems are ecosystems which are found on land. Examples include tundra, taiga, temperate deciduous forest, tropical rain forest, grassland, deserts. Terrestrial ecosystems differ from aquatic ecosystems by the predominant pr ...

s due to the

biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms biom ...

transfer provided by their mass migration between oceanic and inland waterbodies.

Evolution

Current salmonids comprise three lineages, taxonomically treated as

subfamilies In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

: Coregoninae (

es), Thymallinae (

grayling Grayling or Greyling may refer to: Animals Fish * Grayling, generically, any fish of the genus ''Thymallus'' in the family Salmonidae ** European grayling (''Thymallus thymallus''), the European species of the genus ''Thymallus'' ** Arctic grayli ...

s), and

Salmoninae 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 whitefish ...

(

, char, taimens and

s). Generally, all three lineages are accepted to allocate a suite of derived traits indicating a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

group. The Salmonidae first appear in the

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

record in the

Middle Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "d ...

with '' Eosalmo driftwoodensis'', which was first described from fossils found at

Driftwood Creek Driftwood Creek is a stream in North Slope Borough, Alaska, in the United States. It is a tributary of the Utukok River. Driftwood Creek was named for the driftwood collected there by surveyors for their campfires. See also *List of rivers of Ala ...

, central

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...

. This genus shares traits found in all three subfamily lineages. Hence, ''E. driftwoodensis'' is an archaic salmonid, representing an important stage in salmonid evolution. A gap appears in the salmonine fossil record after ''E. driftwoodensis'' until about 7 million years ago (

mya Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese ...

), in the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene Epoch made up of two stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million years ago) to 5.333 Ma. The ...

, when trout-like fossils appear in

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and W ...

, in the Clarkia Lake beds. Several of these species appear to be ''

Oncorhynchus ''Oncorhynchus'' is a genus of fish in the family Salmonidae; it contains the Pacific salmon and Pacific trout. The name of the genus is derived from the Greek ὄγκος (ónkos, “lump, bend”) + ῥύγχος (rhúnkhos, “snout”), in r ...

'' — the current genus for Pacific salmon and Pacific trout. The presence of these species so far inland established that ''Oncorhynchus'' was not only present in the Pacific drainages before the beginning of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58rainbow A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It takes the form of a multicoloured circular arc. Rainbows ...

and

cutthroat trout The cutthroat trout is a fish species of the family Salmonidae native to cold-water tributaries of the Pacific Ocean, Rocky Mountains, and Great Basin in North America. As a member of the genus ''Oncorhynchus'', it is one of the Pacific ...

, and Pacific salmon lineages had diverged before the beginning of the Pliocene. Consequently, the split between ''Oncorhynchus'' and ''

'' (Atlantic salmon and European trout) must have occurred well before the Pliocene. Suggestions have gone back as far as the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was p ...

(about 20 mya).

Genetics

Based on the most current evidence, salmonids diverged from the rest of

teleost fish Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tele ...

no later than 88 million years ago, during the late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

. This divergence was marked by a whole-genome duplication event in the ancestral salmonid, where the diploid ancestor became

tetraploid Polyploidy is a condition in which the cells of an organism have more than one pair of (homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains ...

. This duplication is the fourth of its kind to happen in the evolutionary lineage of the salmonids, with two having occurred commonly to all bony vertebrates, and another specifically in the teleost fishes. Extant salmonids all show evidence of partial tetraploidy, as studies show the genome has undergone selection to regain a diploid state. Work done in the

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead (sometimes called "steelhead trout") is an anadromous (sea-run) form of the coast ...

(''Onchorhynchus mykiss'') has shown that the genome is still partially-tetraploid. Around half of the duplicated protein-coding genes have been deleted, but all apparent miRNA sequences still show full duplication, with potential to influence regulation of the rainbow trout's genome. This pattern of partial tetraploidy is thought to be reflected in the rest of extant salmonids. The first fossil species representing a true salmonid fish ('' E. driftwoodensis'') does not appear until the middle Eocene. This fossil already displays traits associated with extant salmonids, but as the genome of E. ''driftwoodensis'' cannot be sequenced, it cannot be confirmed if polyploidy was present in this animal at this point in time. This fossil is also significantly younger than the proposed salmonid divergence from the rest of the teleost fishes, and is the earliest confirmed salmonid currently known. This means that the salmonids have a ghost lineage of approximately 33 million years. Given a lack of earlier transition fossils, and the inability to extract genomic data from specimens other than extant species, the dating of the whole-genome duplication event in salmonids was historically a very broad categorization of times, ranging from 25 to 100 million years in age. New advances in calibrated relaxed molecular clock analyses have allowed for a closer examination of the salmonid genome, and has allowed for a more precise dating of the whole-genome duplication of the group, that places the latest possible date for the event at 88 million years ago. This more precise dating and examination of the salmonid whole-genome duplication event has allowed more speculation on the radiation of species within the group. Historically, the whole-genome duplication event was thought to be the reason for the variation within Salmonidae. Current evidence done with molecular clock analyses revealed that much of the speciation of the group occurred during periods of intense climate change associated with the last ice ages, with especially high speciation rates being observed in salmonids that developed an anadromous lifestyle.

Classification

Together with the closely related

Esociformes The Esociformes () are a small order of ray-finned fish, with two families, Umbridae and Esocidae. The pikes of genus ''Esox'' give the order its name. This order is closely related to the Salmoniformes, the two comprising the superorder ...

(the pikes and related fishes), Osmeriformes (e.g.

smelt Smelt may refer to: * Smelting, chemical process * The common name of various fish: ** Smelt (fish), a family of small fish, Osmeridae ** Australian smelt in the family Retropinnidae and species ''Retropinna semoni'' ** Big-scale sand smelt ''A ...

s), and

Argentiniformes The Argentiniformes are an order of ray-finned fish whose distinctness was recognized only fairly recently. In former times, they were included in the Osmeriformes (typical smelt and allies) as suborder Argentinoidei. That term refers only to t ...

, the Salmoniformes comprise the

superorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

Protacanthopterygii. The Salmonidae are divided into three subfamilies and around 10 genera containing about 220 species. The concepts of the number of species recognised vary among researchers and authorities; the numbers presented below represent the higher estimates of diversity: Order Salmoniformes * Family: Salmonidae ** Subfamily: Coregoninae *** ''

Coregonus ''Coregonus'' is a diverse genus of fish in the salmon family ( Salmonidae). The ''Coregonus'' species are known as whitefishes. The genus contains at least 68 described extant taxa, but the true number of species is a matter of debate. The ty ...

'' - whitefishes (78 species) *** ''

Prosopium ''Prosopium'' is a genus of freshwater whitefishes found in North America and parts of eastern Russia. It contains three fairly widespread species: the round whitefish, the pygmy whitefish, and the mountain whitefish. The remaining species, the ...

'' - round whitefishes (six species) *** '' Stenodus'' - beloribitsa and nelma (one or two species) ** Subfamily: Thymallinae *** ''

Thymallus ''Thymallus'' is a genus of freshwater fish in the salmon family Salmonidae; it is the only genus of subfamily Thymallinae. The type species is '' Thymallus thymallus,'' the grayling. The species in the genus are generically called graylings, ...

'' - graylings (14 species) ** Subfamily: Salmoninae ***

Tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confl ...

: Salmonini **** ''

'' - Atlantic salmon and

(47 species) **** ''

Salvelinus ''Salvelinus'' is a genus of salmonid fish often called char or charr; some species are called "trout". ''Salvelinus'' is a member of the subfamily Salmoninae within the family Salmonidae. The genus has a northern circumpolar distribution, and ...

'' - Char and trout (e.g. brook trout,

lake trout The lake trout (''Salvelinus namaycush'') is a freshwater char living mainly in lakes in northern North America. Other names for it include mackinaw, namaycush, lake char (or charr), touladi, togue, and grey trout. In Lake Superior, it can als ...

) (51 species) **** ''

Salvethymus ''Salvethymus svetovidovi'', also called the long-finned charr, is a species of salmonid fish. It is endemic to Elgygytgyn Lake in Chukotka, Far East of Russia,Kottelat, M. 1996.''Salvethymus svetovidovi'' 2006 IUCN Red List of Threatened Specie ...

'' -

Long-finned char ''Salvethymus svetovidovi'', also called the long-finned charr, is a species of salmonid fish. It is endemic to Elgygytgyn Lake in Chukotka, Far East of Russia,Kottelat, M. 1996.''Salvethymus svetovidovi'' 2006 IUCN Red List of Threatened Species ...

(one species) *** Tribe: Oncorhynchini **** '' Brachymystax'' -

s (four species) ****

† A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species). It is one of the modern descendan ...

'' Eosalmo'' (one species,

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

) **** ''

Hucho ''Hucho'' is a genus of large piscivorous salmonid fish known as taimens (from Finnish through Russian ), and is closely related to Pacific trout and lenoks (all belonging to the same tribe in the subfamily Salmoninae). Native to the cold ...

'' - taimens (four species) **** ''

'' - Pacific salmon and trout (12 species) **** '' Parahucho'' - Sakhalin taimen (one species)

Hybrid crossbreeding

The following table shows results of hybrid crossbreeding combination in Salmonidae. note :- : The identical kind, O : (survivability), X : (Fatality)

Evolution

Genetics

Classification

Hybrid crossbreeding

References

Further reading