Salmonidae Temporal range: | |
---|---|
Chinook salmon (Oncorhynchus tschawytscha) | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Superorder: | Protacanthopterygii |
Order: | Salmoniformes Bleeker, 1859 |
Family: | Salmonidae G. Cuvier, 1816 |
Type species | |
Salmo | |
Genera | |
(see text) |
Salmonidae ( /sælˈmɒnɪdiː/ , lit. "salmon-like") is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes ( /sælˈmɒnɪfɔːrmiːz/ , lit. "salmon-shaped"), consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmon (both Atlantic and Pacific species), trout (both ocean-going and landlocked), char, graylings, freshwater whitefishes, taimens and lenoks, all coldwater mid-level predatory fish that inhabit the subarctic and cool temperate waters of the Northern Hemisphere. The Atlantic salmon (Salmo salar), whose Latin name became that of its genus Salmo , is also the eponym of the family and order names.
Salmonids have a relatively primitive appearance among teleost fish, with the pelvic fins being placed far back, and an adipose fin towards the rear of the back. They have slender bodies with rounded scales and forked tail fins, and their mouths contain a single row of sharp teeth. [2] Although the smallest salmonid species is just 13 cm (5.1 in) long for adults, most salmonids are much larger, with the largest reaching 2 m (6 ft 7 in). [3]
All salmonids are migratory fish that spawn in the shallow gravel beds of freshwater headstreams, spend the growing juvenile years in rivers, creeks, small lakes and wetlands, but migrate downstream upon maturity and spend most of their adult lives at much larger waterbodies. Many salmonid species are euryhaline and migrate to the sea or brackish estuaries as soon as they approach adulthood, returning to the upper streams only to reproduce. Such sea-run life cycle is described as anadromous , and other freshwater salmonids that migrate purely between lakes and rivers are considered potamodromous . Salmonids are carnivorous predators of the middle food chain, feeding on smaller fish, crustaceans, aquatic insects and larvae, tadpoles and sometimes fish eggs (even those of their own kind), [2] and in turn being preyed upon by larger predators. Many species of salmonids are thus considered keystone organisms important for both freshwater and terrestrial ecosystems due to the biomass transfer provided by their mass migration from oceanic to inland waterbodies.
Current salmonids comprise three lineages, taxonomically treated as subfamilies: Coregoninae (freshwater whitefishes), Thymallinae (graylings), and Salmoninae (trout, salmon, char, taimens and lenoks). Generally, all three lineages are accepted to allocate a suite of derived traits indicating a monophyletic group. [1]
The order Salmoniformes is most closely related to pike and mudminnows in the order Esociformes, to the extent that some authors have grouped the Esociformes within the Salmoniformes. [4] Although it is assumed that salmon and pike diverged from one another during the Cretaceous, no definitive salmonids appear before the Eocene. [5] The Salmonidae first appear in the fossil record in the Early Eocene [6] with Eosalmo driftwoodensis , a stem-salmonine, which was first described from fossils found at Driftwood Creek, central British Columbia, [5] and has been recovered from most sites in the Eocene Okanagan Highlands. [7] [8] [9] This genus shares traits found in all three subfamily lineages. Hence, E. driftwoodensis is an archaic salmonid, representing an important stage in salmonid evolution. [1] Fossil scales of coregonines are known from the Late Eocene or Early Oligocene of California. [10]
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, in the Clarkia Lake beds. [11] 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 (~5–6 mya), but also that rainbow and cutthroat trout, and Pacific salmon lineages had diverged before the beginning of the Pliocene. Consequently, the split between Oncorhynchus and Salmo (Atlantic salmon and European trout) must have occurred well before the Pliocene. Suggestions have gone back as far as the Early Miocene (about 20 mya). [1] [12]
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. This divergence was marked by a whole-genome duplication event in the ancestral salmonid, where the diploid ancestor became tetraploid. [13] [14] 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. [14]
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. [15]
The first fossil species representing a true salmonid fish ( E. driftwoodensis ) does not appear until the middle Eocene. [16] 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. [15] 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. [14]
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. [14]
Together with the closely related orders Esociformes (pikes and mudminnows), Osmeriformes (true smelts) and Argentiniformes (marine smelts and barreleyes), Salmoniformes comprise the superorder Protacanthopterygii.
The only extant family within Salmoniformes, Salmonidae, is 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: [3]
Phylogeny of Salmonidae [17] [18] | |||||||||||||||
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Order Salmoniformes
The following table shows results of hybrid crossbreeding combination in Salmonidae. [19]
Crossbreeding | |||||||||||||
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male | |||||||||||||
Salvelinus | Oncorhynchus | Salmo | |||||||||||
leucomaenis (white-spotted char) | fontinalis (Brook trout) | mykiss (Rainbow trout) | masou masou (masu salmon) | masou ishikawae (Amago Salmon) | gorbuscha (pink salmon) | nerka (Sockeye salmon) | keta (chum salmon) | kisutsh (coho salmon) | tshawytscha (chinook salmon) | trutta (Brown trout) | salar (Atlantic Salmon) | ||
female | |||||||||||||
(Salvelinus) | leucomaenis (white-spotted char) | - | O | X | O | O | X | X | O | ||||
fontinalis (Brook trout) | O | - | X | O | O | X | X | O | X | X | |||
(Oncorhynchus) | mykiss (Rainbow trout) | O | O | - | O | O | O | X | X | X | X | X | |
masou masou (masu salmon) | O | X | X | - | O | X | X | O | O | X | |||
masou ishikawae (Amago Salmon) | O | O | X | O | - | X | O | ||||||
gorbuscha (pink salmon) | X | - | O | O | O | ||||||||
nerka (Sockeye salmon) | X | X | X | X | X | O | - | O | O | O | X | ||
keta (chum salmon) | X | X | X | X | O | O | - | O | X | X | |||
kisutsh (coho salmon) | X | X | O | O | X | - | O | X | X | ||||
tshawytscha (chinook salmon) | O | O | O | X | O | - | |||||||
Salmo | trutta (Brown trout) | O | O | X | O | O | X | X | - | O | |||
salar (Atlantic Salmon) | O | X | X | X | O | - |
note :- : The identical kind, O : (survivability), X : (Fatality)
Actinopterygii, members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin supported by radially extended thin bony spines called lepidotrichia, as opposed to the bulkier, fleshy lobed fins of the sister class Sarcopterygii. Resembling folding fans, the actinopterygian fins can easily change shape and wetted area, providing superior thrust-to-weight ratios per movement compared to sarcopterygian and chondrichthyian fins. The fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the articulation between these fins and the internal skeleton.
Salmon is the common name for several commercially important species of euryhaline ray-finned fish from the genera Salmo and Oncorhynchus of the family Salmonidae, native to tributaries of the North Atlantic (Salmo) and North Pacific (Oncorhynchus) basins. Other closely related fish in the same family include trout, char, grayling, whitefish, lenok and taimen, all coldwater fish of the subarctic and cooler temperate regions with some sporadic endorheic populations in Central Asia.
Trout is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera Oncorhynchus, Salmo and Salvelinus, all of which are members of the subfamily Salmoninae in the family Salmonidae. The word trout is also used for some similar-shaped but non-salmonid fish, such as the spotted seatrout/speckled trout.
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 Protacanthopterygii, which also includes pike and salmon, among others. The order's name means "smelt-shaped", from Osmerus + the standard fish order suffix "-formes". It ultimately derives from Ancient Greek osmé + Latin forma, the former in reference to the characteristic aroma of the flesh of Osmerus.
Siberian taimen, also known as the common taimen, Siberian giant trout or Siberian salmon, is a species of salmon-like ray-finned fish from the genus Hucho in the family Salmonidae. These fish are found in rivers in Siberia and adjacent regions, and are harvested throughout the year.
The rainbow trout is a species of trout native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead is an anadromous (sea-run) form of the coastal rainbow trout(O. m. irideus) or Columbia River redband trout (O. m. gairdneri) that usually returns to freshwater to spawn after living two to three years in the ocean. Freshwater forms that have been introduced into the Great Lakes and migrate into tributaries to spawn are also called steelhead.
Salmo is a genus of ray-finned fish from the subfamily Salmoninae of family Salmonidae, and is part of the tribe Salmonini along with the sister genera Salvelinus and Salvethymus. Almost all Salmo species are native only in the Old World, the only exception being the Atlantic salmon, which is also naturally found across the North Atlantic in eastern North America.
The Apache trout or Arizona trout, Oncorhynchus apache, is a species of freshwater fish in the salmon family of order Salmoniformes. It is one of the Pacific trouts.
Pink salmon or humpback salmon is a species of euryhaline ray-finned fish in the family Salmonidae. It is the type species of the genus Oncorhynchus, and is the smallest and most abundant of the seven officially recognized species of salmon. The species' scientific name is based on the Russian common name for this species gorbúša (горбуша), which literally means humpie.
Oncorhynchus is a genus of ray-finned fish in the subfamily Salmoninae of the family Salmonidae, native to coldwater tributaries of the North Pacific basin. The genus contains twelve extant species, namely six species of Pacific salmon and six species of Pacific trout, all of which are migratory mid-level predatory fish that display natal homing and semelparity.
Hucho is a genus of large piscivorous salmonid fish known as taimens, and is closely related to Pacific trout and lenoks. Native to the cold rivers and other freshwater habitats in Eurasia, they are threatened by overfishing and habitat loss.
The westslope cutthroat trout, also known as the black-spotted trout, common cutthroat trout and red-throated trout is a subspecies of the cutthroat trout and is a freshwater fish in the salmon family of order Salmoniformes. The cutthroat is the Montana state fish. This subspecies is a species of concern in its Montana and British Columbia ranges and is considered threatened in its native range in Alberta.
Eosalmo is an extinct genus of ancient salmonid that lived during the Eocene epoch.
Lenoks, otherwise known as Asiatic trout or Manchurian trout, are salmonid fish of the genus Brachymystax, native to rivers and lakes in Mongolia, Kazakhstan, wider Siberia, Northern China and Korea.
Brachymystax lenok, the sharp-snouted lenok, is a salmonid fish distributed in rivers and lakes in northeastern Asia. It formerly included the blunt-snouted lenok, but recent authorities typically treat the latter as a separate species, B. tumensis, based on differences in morphology and genetics.
Diseases and parasites in salmon, trout and other salmon-like fishes of the family Salmonidae are also found in other fish species. The life cycle of many salmonids is anadromous, so such fish are exposed to parasites in fresh water, brackish water and saline water.
The Baja California rainbow trout or San Pedro Martir trout or Nelson's trout is a localized subspecies of the rainbow trout, a freshwater fish in the family Salmonidae.
Brachymystax tumensis, commonly known as the blunt-snouted lenok or Tumen lenok, is a salmonid fish distributed in rivers and lakes in Eastern Asia. It was formerly included in the more widespread species Brachymystax lenok, but more recent research based on differences in morphology and genetics have justified a distinction of the two species.
Salvelinus alpinus erythrinus, also known as Baikal charr or davatchan, is a subspecies of freshwater fish in the salmon family. It is endemic to the mountains north of Lake Baikal in the Russian Far East. The fish is edible and it is reported that the population of the species shrunk rapidly over the recent years due to over-fishing.