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 ...
of
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 Salmoniformes . It includes
salmon
Salmon () is the common name for several commercially important species of euryhaline ray-finned fish from the family Salmonidae, which are native to tributaries of the North Atlantic (genus ''Salmo'') and North Pacific (genus '' Oncorhy ...
(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-salm ...
(both ocean-going and landlocked),
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, th ...
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 of the ...
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 nom ...
''
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. Tele ...
fish, with the
pelvic fins 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 se ...
towards the rear of the back. They have slender bodies, with rounded
scales and forked tails, and their
mouths 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 of
upper reaches of
river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of w ...
s and
creeks, but in many cases, the fish spend most of their adult lives at
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 estu ...
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 environmen ...
, returning to the rivers only to reproduce. This lifecycle is described as
anadromous. Salmonids are
carnivorous 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 th ...
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), de ...
, 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 group can ...
s,
aquatic insects and smaller fish,
[ and in turn being preyed upon by larger predators. Many species of salmonids are thus considered keystone organisms important for both freshwater 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 pres ...
s due to the biomass transfer provided by their mass migration between oceanic and inland waterbodies.
Evolution
Current salmonids comprise three lineages, taxonomically treated as subfamilies: Coregoninae (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, th ...
es), Thymallinae ( graylings), 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 whitefis ...
(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-salm ...
, salmon
Salmon () is the common name for several commercially important species of euryhaline ray-finned fish from the family Salmonidae, which are native to tributaries of the North Atlantic (genus ''Salmo'') and North Pacific (genus '' Oncorhy ...
, char, 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). Generally, all three lineages are accepted to allocate a suite of derived traits indicating a 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'', "da ...
with '' Eosalmo driftwoodensis'', which was first described from fossils found at Driftwood Creek, central British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
. 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), in the Late Miocene, 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 Wyomi ...
, in the Clarkia Lake beds. Several of these species appear to be '' Oncorhynchus'' — 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 2.58[rainbow
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 c ...](_blank)
and cutthroat trout, and Pacific salmon lineages had diverged before the beginning of the Pliocene. Consequently, the split between ''Oncorhynchus'' and ''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, '' ...
'' (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 (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages.
The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...
(about 20 mya).
Genetics
Based on the most current evidence, salmonids diverged from the rest of teleost fish 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 (''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 pikes and related fishes), Osmeriformes
The Osmeriformes are an order of ray-finned fish that includes the true or freshwater smelts and allies, such as the galaxiids and noodlefishes; they are also collectively called osmeriforms. They belong to the teleost superorder Protacanthopt ...
(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 ''Ath ...
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 ...
, the Salmoniformes comprise the superorder Protacanthopterygii
Protacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitats. They appear to have evolved in the Cretaceous or perhaps late Jurassic, originating probably roug ...
.
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 typ ...
'' - 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 B ...
'' - round whitefishes (six species)
*** '' Stenodus'' - beloribitsa and nelma
''Stenodus nelma'', known alternatively as the nelma, sheefish, siifish, inconnu or connie, is a commercial species of freshwater whitefish in the family Salmonidae. It is widespread in the Arctic rivers from the Kola Peninsula (White Sea basin) ...
(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, bu ...
'' - 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 confli ...
: Salmonini
**** ''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, '' ...
'' - Atlantic salmon and 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-salm ...
(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 also ...
) (51 species)
**** '' Salvethymus'' - Long-finned char (one species)
*** Tribe: Oncorhynchini
**** '' Brachymystax'' - 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 (four species)
**** †'' Eosalmo
''Eosalmo'' is an extinct genus of ancient salmonid that lived during the Eocene geological epoch, epoch.
The genus was type locality (geology), first described in 1977 from fossils found in lake, lacustrine deposits in Driftwood Canyon Provin ...
'' (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 ...
'' - taimen
Siberian taimen (''Hucho taimen''), also known as the common taimen (russian: Обыкнове́нный тайме́нь, Obyknovénnyĭ taĭménʹ), Siberian giant trout or Siberian salmon, is a species of salmon-like ray-finned fish from the ...
s (four species)
**** '' Oncorhynchus'' - Pacific salmon and trout (12 species)
**** '' Parahucho'' - Sakhalin taimen
The Sakhalin taimen (''Parahucho perryi'', syn. ''Hucho perryi''), also known as the Japanese huchen or stringfish ( ja, 糸魚/イトヨ, itoyo), is a large species of salmonid freshwater fish in Northeast Asia, found in the lakes and large riv ...
(one species)
Hybrid crossbreeding
The following table shows results of hybrid crossbreeding combination in Salmonidae.
note :- : The identical kind, O : (survivability), X : (Fatality)
References
Further reading
* Behnke, Robert J. ''Trout and Salmon of North America,'' Illustrated by Joseph R. Tomelleri. 1st Chanticleer Press ed. New York: The Free Press, 2002.
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{{Authority control
Ray-finned fish families
Articles which contain graphical timelines
Extant Late Cretaceous first appearances
Taxa named by Georges Cuvier