''Salmo trutta fario'', sometimes called the river trout, is a

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

-dwelling

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

predatory fish Predatory fish are hypercarnivorous fish that actively prey upon other fish or aquatic animals, with examples including shark, billfish, barracuda, alligator gar, tuna, dolphinfish, walleye, perch and salmon. Some omnivorous fish, such as t ...

from the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Salmo ''Salmo'' is a genus of ray-finned fish from the subfamily Salmoninae of family (biology), family Salmonidae, and is part of the tribe (biology), tribe Salmonini along with the sister genera ''Salvelinus'' and ''Salvethymus''. Almost all ''Salmo ...

'' of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Salmonidae Salmonidae (, ) is a family (biology), family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmo ...

. It is one of the three main

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of the

brown trout The brown trout (''Salmo trutta'') is a species of salmonid ray-finned fish and the most widely distributed species of the genus ''Salmo'', endemic to most of Europe, West Asia and parts of North Africa, and has been widely introduced globally ...

(''

Salmo trutta The brown trout (''Salmo trutta'') is a species of salmonid ray-finned fish and the most widely distributed species of the genus ''Salmo'', endemic to most of Europe, West Asia and parts of North Africa, and has been widely introduced species, in ...

''), besides

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 bull trout, sewin (Wales ...

(''

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 bull trout, sewin (Wales), ...

'') and the lacustrine trout (''

Salmo trutta lacustris The brown trout (''Salmo trutta'') is a species of salmonid ray-finned fish and the most widely distributed species of the genus ''Salmo'', endemic to most of Europe, West Asia and parts of North Africa, and has been widely introduced globally a ...

'').

Description

Depending on the supply of food, river trout measure 20 to 80 cm (0.7–2.6 ft) in length; exceptionally, they may be up to 1 m (3.3 ft) long and weigh up to over 13 kg (29 lb), although they usually attain an average weight of up to 2 kg (4.4 lb). Their back is olive-dark brown and silvery blue, red spots with light edges occur towards the belly, and the belly is whitish yellow. They can live for up to 18 years.

Habitat

Like other salmonids, river trout live in cool, fast-flowing, oxygen-rich, clear waters with

gravel Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone. Gr ...

sandy Sandy may refer to: People and fictional characters *Sandy (given name), including a list of people and fictional characters with the given name or nickname * Sandy (surname), a list of people * Sandy (Iranian music band), Iranian singer, comp ...

riverbeds A streambed or stream bed is the bottom of a stream or river and is confined within a channel or the banks of the waterway. Usually, the bed does not contain terrestrial (land) vegetation and instead supports different types of aquatic vegeta ...

. Their native ranges occur across almost all of

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

, from

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

on the

Iberian Peninsula The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, comprisin ...

to the

Volga The Volga (, ) is the longest river in Europe and the longest endorheic basin river in the world. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catchment ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

, and are found as far north as Lapland. They can be found in most northern Mediterranean and western

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

tributaries but not in

Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...

, Central Anatolia and the

Caucasus The Caucasus () or Caucasia (), is a region spanning Eastern Europe and Western Asia. It is situated between the Black Sea and the Caspian Sea, comprising parts of Southern Russia, Georgia, Armenia, and Azerbaijan. The Caucasus Mountains, i ...

regions or on

Corsica Corsica ( , , ; ; ) is an island in the Mediterranean Sea and one of the Regions of France, 18 regions of France. It is the List of islands in the Mediterranean#By area, fourth-largest island in the Mediterranean and lies southeast of the Metro ...

Sardinia Sardinia ( ; ; ) is the Mediterranean islands#By area, second-largest island in the Mediterranean Sea, after Sicily, and one of the Regions of Italy, twenty regions of Italy. It is located west of the Italian Peninsula, north of Tunisia an ...

and

Sicily Sicily (Italian language, Italian and ), officially the Sicilian Region (), is an island in the central Mediterranean Sea, south of the Italian Peninsula in continental Europe and is one of the 20 regions of Italy, regions of Italy. With 4. ...

islands. River trout are faithful to their habitat, leaving the

home range A home range is the area in which an animal lives and moves on a periodic basis. It is related to the concept of an animal's territory which is the area that is actively defended. The concept of a home range was introduced by W. H. Burt in 1943. ...

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...

for smaller upstream

headwaters The headwater of a river or stream is the geographical point of its beginning, specifically where surface runoff water begins to accumulate into a flowing channel of water. A river or stream into which one or many tributary rivers or streams flo ...

to reproduce. Even after being disturbed, they return to their traditional sites. The adult river trout requires its

territory A territory is an area of land, sea, or space, belonging or connected to a particular country, person, or animal. In international politics, a territory is usually a geographic area which has not been granted the powers of self-government, ...

. During the day, it is hidden in the shadows of the river bank, facing upstream. Depending on size and habitat, they feed mainly on

insects Insects (from Latin ') are 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 pairs of jointed ...

and

larvae A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...

, small

baitfish 300px, Feeder Goldfish are common baitfish. Bait fish (or baitfish) are small-sized fish caught and used by anglers as bait to attract larger predatory fish, particularly game fish. Baitfish species are typically those that are common and bre ...

(such as

European bullhead The European bullhead (''Cottus gobio'') is a freshwater fish that is widely distributed in Europe, mainly in rivers. It is a member of the family Cottidae, a type of sculpin. It is also known as the miller's thumb, freshwater sculpin, common bu ...

), small

crustaceans Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of Arthropod, arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquat ...

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

and other water animals.

Cannibalism Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is also well document ...

has also been frequently observed among river trout. They are fast-swimming pursuit predators, but in faster-flowing rivers and streams, they are usually

opportunistic 300px, ''Opportunity Seized, Opportunity Missed'', engraving by Theodoor Galle, 1605 Opportunism is the practice of taking advantage of circumstances — with little regard for principles or with what the consequences are for others. Opport ...

and will take prey that is floating past by the current.

Reproduction

River trout

spawn Spawn or spawning may refer to: * Spawning, 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: Armageddon' ...

between October and January in the

northern hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

, and introduced populations in the southern hemisphere spawn between May and June. The fish uses rapid fanning of the tail and

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

on a rock riverbed to make several shallow pits, into which about 1,000 to 1,500 reddish eggs in size are laid. The

fish larva A fish (: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits. Fish can be grouped into the more basal jawless fish and the more common jawed fis ...

e emerge after two to four months.

Ecology

The river trout has special significance as a

host 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 * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

fish for the

glochidia The glochidium (plural glochidia) is a microscopic larval stage of some freshwater mussels, aquatic bivalve mollusks in the families Unionidae and Margaritiferidae, the river mussels and European freshwater pearl mussels. These larvae are t ...

of the

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

(''Margaritifera margaritifera'').

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 native to Eastern North America in the United States and Canada. Two ecological forms of brook trout h ...

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

gonads A gonad, sex gland, or reproductive gland is a mixed gland and sex organ 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, ...

. By contrast, male tiger trout develop testicles as well as secondary sex features such as kypes, humps, darker and thicker skin and 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 tributary, tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an Fish migration#Classification, ...

, 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 success rate as the rainbow trout for food and 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 back trout that are below the

minimum landing size The minimum landing size (MLS) is the smallest fish measurement at which it is legal to keep or sell a fish. The MLS depends on the species of fish. Sizes also vary around the world, as they are legal definitions which are defined by the local regu ...

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, intended to mimic an emerging or egg-laying

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

. A spinning rod 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. Fish care should be taken when using wobblers and rubber 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 Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance faster than it can be lost or eliminated by catabolism and excretion. T ...

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