Trout

Rainbow trout, Oncorhynchus mykiss

Biwa trout (or Biwa salmon), Oncorhynchus masou rhodurus

Trout is the common name for several species of freshwater and anadromous fish in the family Salmonidae, whose members also include salmon, whitefish, char, and their relatives. Sometimes the term "trout" is used to refer more generally to any member of the Salmoniformes order, which includes only the one family Salmonidae (ITIS 2004; Nelson 2006). All fish called trout are members of the subfamily Salmoninae, and in particular certain fish in the genera Salvelinus (chars), Salmo (Atlantic trouts), and Oncorhynchus (Pacific trouts and Pacific salmon).

Overview and description

Salmonidae is a family of ray-finned fish (class (Actinopterygii), the only living family of the order Salmoniformes. The Atlantic salmons and trouts of genus Salmo give the family and order their names.

Salmonidae is divided by Nelson (2006) into three subfamilies: Coregoninae, Thymallinae, and Salmoninae. Fish called trout are all part of the Salmoninae subfamily, and part of three of the seven genera in the subfamily: Salvelnus, Salmo, and Oncorhynchus. Members of the genus Salvelinus are often called "chars" or charrs, with species known as trout found in the two subgenera of Baione (Salvelinus fontinalis, the brook trout), and S. namaycus, lake trout) and Salvelinus (bull trout) (Nelson 2006). Members of the genus Salmo are commonly known as "Atlantic trouts," although this genus also includes a fish known as the Atlantic salmon. Members of the genus Oncorhynchus are known as the "Pacific trouts and Pacific salmon," with the salmon placed in the subgenus Oncorhynchus (Pacific salmon) and the trouts in the subgenus Rhabdofario (Pacific trouts, such as the cutthroat trout, golden trout, and rainbow trout).

Members of the Salmonidae family characterized by the presence of a small adipose (fatty) fin along the back, near the tail; gill members extending far forward, free from isthmus; the presence of a pelvic axillary process; 50 to 75 vertebrae with the last three vertebrae turned up; 7 to 20 brachiostegal rays; and a tetraploid karyotype (Nelson 2006). They lack spines in their rays. Members of the Salmoninae subfamily have fewer than 16 dorsal fin rays, small scales, teeth on the maxilla; and presence of orbitosphenoid and suprapreopercular (Nelson 2006). Trout include freshwater and anadromous members, which are native to the Northern Hemisphere, but are now widely distributed.

Trout that live in different environments can have dramatically different colorations and patterns. Mostly, these colors and patterns form as camouflage, based on the surroundings, and will change as the fish moves to different habitats. Trout in, or newly returned from the sea, can look very silvery, while the same "genetic" fish living in a small stream or in an alpine lake could have pronounced markings and more vivid coloration. It is virtually impossible to define a consistent, definitive color pattern for a specific breed.

There are many species, and even more populations that are isolated from each other and morphologically different. However, since many of these distinct populations show no significant genetic differences, what may appear to be a large number of species is considered a much smaller number of distinct species by most ichthyologists. The trout found in the eastern United States are a good example of this. The brook trout, the aurora trout, and the (extinct) silver trout all have physical characteristics and colorations that distinguish them, yet genetic analysis shows that they are one species, Salvelinus fontinalis.

Lake trout (Salvelinus namaycush), like brook trout, actually belong to the char genus. Lake trout inhabit many of the larger lakes in North America, and live much longer than rainbow trout, which have an average maximum lifespan of 7 years. Lake trout can live many decades, and can grow to more than Template:Kg to lb.

Species

 Fish referred to as trout include:

• Genus Salmo
  • Adriatic trout, Salmo obtusirostris
  • Brown trout, Salmo trutta
  • Flathead trout, Salmo platycephalus
  • Marmorata, Soca River trout or Soča trout - Salmo trutta marmoratus
  • Ohrid trout, Salmo letnica
  • Sevan trout, Salmo ischchan

• Genus Oncorhynchus
  • Apache trout, Oncorhynchus Apache
  • Eskimo trout, Oncorhynchus inupiat
  • Seema, Oncorhynchus masou
  • Cutthroat trout, Oncorhynchus clarki
    The cutthroat trout has 14 recognized subspecies (depending on your sources), such as the Lahontan cutthroat trout, Oncorhynchus clarki henshawi, Bonneville cutthroat trout, Oncorhynchus clarki utah, Colorado River cutthroat trout, Yellowstone cutthroat trout.
  • Gila trout, Oncorhynchus gilae
  • Golden trout, Oncorhynchus aguabonita
  • Rainbow trout, Oncorhynchus mykiss
  • Mexican Golden Trout, Oncorhynchus chrysogaster and as many as eight other species or sub-species in northwest Mexico, not yet formally named.

• Genus Salvelinus (Char)
  • Arctic char, Salvelinus alpinus
  • Aurora trout, Salvelinus fontinalis timagamiensis
  • Brook trout, Salvelinus fontinalis
  • Bull trout, Salvelinus confluentus
  • Dolly Varden trout, Salvelinus malma
  • Lake trout, Salvelinus namaycush
  • Silver trout, † Salvelinus fontinalis agassizi (extinct)

Habitat

A trout farm in Sochi, Russia.

Trout are usually found in cool (50-60°F, 10-15°C), clear streams and lakes, although many of the species have anadromous strains as well. Young trout are referred to as troutlet or troutling. They are distributed naturally throughout North America, northern Asia and Europe. Several species of trout were introduced to Australia and New Zealand by amateur fishing enthusiasts in the 19th century, effectively displacing and endangering several upland native fish species. The introduced species included brown trout from England and rainbow trout from California. The rainbow trout were a steelhead strain, generally accepted as coming from Sonoma Creek. The rainbow trout of New Zealand still show the steelhead tendency to run up rivers in winter to spawn. The speckled trout, found in the Gulf of Mexico and other places in the United States, is not in fact a trout at all, but a member of the drum family.

River fishing

Understanding how moving water shapes the stream channel will improve your chances of finding trout. In most streams, the current creates a Riffle-Run-Pool pattern that repeats itself over and over. A deep pool may hold a big brown trout, but rainbows and smaller browns are likely found in runs. Riffles are where you will find small trout, called troutlet, during the day and larger trout crowding in during morning and evening feeding periods.

• Riffles have a fast current and shallow water. This gives way to a bottom of gravel, rubble or boulder. Riffles are morning and evening feeding areas. Trout usually spawn just above or below riffles, but may spawn right in them.

• Runs are deeper than riffles with a moderate current and are found between riffles and pools. The bottom is made up of small gravel or rubble. These hot spots hold trout almost anytime, if there is sufficient cover.

• Pools are smoother and look darker than the other areas of the stream. The deep, slow-moving water generally has a bottom of silt, sand, or small gravel. Pools make good midday resting spots for medium to large trout.

==Food Chain== what is the food trout

Rainbow trout, Oncorhynchus mykiss

File:Golden Trout.jpg

Golden trout, Oncorhynchus aguabonita

Trout Consumption

As a group, trout are somewhat bony, but the flesh is generally considered to be appetizing. Additionally, they provide a good fight when caught with a hook and line, and are sought after recreationally. Because of their popularity, trout are often raised on fish farms and planted into heavily fished waters, in an effort to mask the effects of overfishing. While they can be caught with a normal rod and reel, fly fishing is a distinctive method developed primarily for trout, and now extended to other species. Farmed trout and char are also sold commercially as food fish.

References

ISBN links support NWE through referral fees

• Trout and Salmon of North America, Robert J. Behnke, Illustrated by Joseph R. Tomelleri, The Free Press, 2002, hardcover, 359 pages, ISBN 0-7432-2220-2
• Trout Science, [1], 2000, knowledgebase article

• Integrated Taxonomic Information System (ITIS). 2003. Salmoniformes ITaxonomic Serial No.: 161929. Retrieved September 11, 2008.

• Nelson, J. S. 2006. Fishes of the World, 4th edition. Hoboken, NJ: John Wiley & Sons. ISBN 0471250317.

External links

• {{{2}}} at the Open Directory Project

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