''Salmo trutta fario'', sometimes called the river trout, and also known by the name of its parent species, the

brown trout The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morp ...

, is a

predatory fish Predatory fish are hypercarnivorous fish that actively prey upon other fish or aquatic animals, with examples including shark, billfish, barracuda, pike/ muskellunge, walleye, perch and salmon. Some omnivorous fish, such as the red-bellie ...

of the family Salmonidae and a subspecies or morph of the brown trout species, '' Salmo trutta'', which also includes

sea trout Sea trout is the common name usually applied to anadromous (sea-run) forms of brown trout (''Salmo trutta''), and is often referred to as ''Salmo trutta'' morpha ''trutta''. Other names for anadromous brown trout are sewin (Wales), peel or peal ...

(''

Salmo trutta trutta Sea trout is the common name usually applied to anadromous (sea-run) forms of brown trout (''Salmo trutta''), and is often referred to as ''Salmo trutta'' morpha ''trutta''. Other names for anadromous brown trout are sewin (Wales), peel or peal ...

'') and a lacustrine trout ('' Salmo trutta lacustris''). Depending on the supply of food, river trout measure in length; exceptionally they may be up to long and weigh up to over . Their back is olive-dark brown and silvery blue, red spots with light edges occur towards the belly, the belly itself is whitish yellow. River trout usually attain a weight of up to . They can live for up to 18 years.

Habitat

River trout live in fast flowing, oxygen-rich, cool clear waters with gravel or sandy riverbeds. They occur across almost all of Europe, from

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of th ...

to the

Volga The Volga (; russian: Во́лга, a=Ru-Волга.ogg, p=ˈvoɫɡə) is the longest river in Europe. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catch ...

, with the exception of

Central Anatolia The Central Anatolia Region ( tr, İç Anadolu Bölgesi) is a geographical region of Turkey. The largest city in the region is Ankara. Other big cities are Konya, Kayseri, Eskişehir, Sivas, and Aksaray. Located in Central Turkey, it is b ...

and the

Caucasus The Caucasus () or Caucasia (), is a region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range, have historica ...

regions. They are found as far north as Lapland. They do not occur in

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders wi ...

or on the islands of

Corsica Corsica ( , Upper , Southern ; it, Corsica; ; french: Corse ; lij, Còrsega; sc, Còssiga) is an island in the Mediterranean Sea and one of the 18 regions of France. It is the fourth-largest island in the Mediterranean and lies southeast of ...

Sardinia Sardinia ( ; it, Sardegna, label=Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label= Algherese and Catalan) is the second-largest island in the Mediterranean Sea, aft ...

and

Sicily (man) it, Siciliana (woman) , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = Ethnicity , demographics1_footnotes = , demographi ...

. River trout are very faithful to their habitat (i.e. they live only at one spot and do not migrate), leaving it only to reproduce. Even after being disturbed they will return to their traditional sites. The adult river trout requires its own territory. During the day it is hidden in the shadows of the river bank, facing upstream. Depending on size and habitat, they feed mainly on

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

s and insect larvae that live in water, small fish such as bullhead, small

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...

snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class ...

s and other water animals. Cannibalism has also been frequently observed among river trout. They are fast swimming predators, but in rivers and streams they will usually take prey that is being driven past by the current.

Reproduction

River trout

spawn Spawn or spawning may refer to: * Spawn (biology), the eggs and sperm of aquatic animals Arts, entertainment, and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** '' Spawn: A ...

between October and January in the northern hemisphere and between May and June in the southern hemisphere. The fish uses rapid fanning of the tail and

caudal 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 ...

on a rock riverbed to make several shallow pits, into which about 1,000 to 1,500 reddish eggs, four to five millimetre wide, are laid. The fish larvae emerge after two to four months. The river trout has a special significances as a

host fish A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host ...

for the glochidia of the

freshwater pearl mussel The freshwater pearl mussel (''Margaritifera margaritifera'') is an endangered species of freshwater mussel, an aquatic bivalve mollusc in the family Margaritiferidae. Although the name "freshwater pearl mussel" is often used for this species, ...

Other forms

Because trout live in habitats with fixed boundaries, in addition to the river trout, ''Salmo trutta fario'', there are various other subspecies of ''Salmo trutta''. ''See Species of Trout.''

Hybrids

The tiger trout (''Salmo trutta fario'' × ''Salvelinus fontinalis'') is a genetic cross between a river trout and a

brook trout The brook trout (''Salvelinus fontinalis'') is a species of freshwater fish in the char genus ''Salvelinus'' of the salmon family Salmonidae. It is native to Eastern North America in the United States and Canada, but has been introduced elsewhere ...

. It gets its name from its characteristic golden yellow markings. Tiger trout are sterile, despite male and female may be distinguished by their external markings. The female tiger trout does not develop any

gonad A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sp ...

s. By contrast, male tiger trout develop testicles as well as secondary sex features such as

kype A kype is a hook-like secondary sex characteristic which develops at the distal tip of the lower jaw in some male salmonids prior to the spawning season. The structure usually develops in the weeks prior to, and during, migration to the spawning ...

s, humps, darker and thicker skin and a lighter fillet colouring during the spawning season.

Fishing

In the past, European waterbodies were heavily and artificially stocked with

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 ...

, a native of America that grows more quickly and is less demanding of water quality. It is disputed whether this threatens the river trout. Today, it is bred in fishponds with almost the same rate of success as the rainbow trout, for food and for restocking rivers. To protect native species of fish, the stocking of rivers with non-native species has been restricted for several years. River trout makes an excellent fish dish.

Angling

River trout is very popular with anglers. It is frequently fished using artificial lures. Angling with natural lures (worms, maggots, grasshoppers) is discouraged in most rivers because it is difficult to throw those trout back that are below the minimum landing size uninjured, when they have ingested this food so quickly and deeply. Fly rods are used to catch river trout. Medium-sized, wet and dry flies are thrown into streams with a rod of AFTMA Class 4-6 and are intended to mimic an emerging or egg-laying

. A

spinning rod A fishing rod is a long, thin rod used by anglers to catch fish by manipulating a line ending in a hook (formerly known as an ''angle'', hence the term "angling"). At its most basic form, a fishing rod is a straight rigid stick/pole with a ...

can also be used in some waters. For this purpose, a light spinning rod and various artificial lures, such as spoon lures and spinners are used. In using wobblers and rubber fish care should be taken because they are banned on some waterbodies or may only be used with restrictions.

Research use

The fish has been used as a bio-indicator species in freshwater systems due to their sensitive nature. They are a well-established ‘model organism’ in aquatic toxicology research, especially for heavy metal bioaccumulation.

References

Literature

* Fritz Terofal: ''Süsswasserfische in europäischen Gewässern.'' Mit 200 farbigen Darstellungen von Fritz Wendler. Mosaik Verlag u. a., München u. a. 1984, . * Alexander Kölbing, Kurt Seifert: ''So macht Angeln Spass. Mehr wissen – mehr fangen.'' 5., durchgesehene Auflage. BLV, München u. a. 1995, . * Roland Gerstmeier, Thomas Romig: ''Die Süßwasserfische Europas. Für Naturfreunde und Angler.'' Kosmos, Stuttgart 1998, .

External links

{{Authority control Salmo Freshwater fish of Europe Fish described in 1758 Taxa named by Carl Linnaeus Morphas