Salmo trutta fario

Riverine brown trout
Salmo trutta forma fario
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Salmoniformes
Family: Salmonidae
Genus: Salmo
Species: S. trutta
Form: Salmo trutta morpha fario
Linnaeus, 1758

Salmo trutta morpha fario is the riverine form or the brown trout Salmo trutta that spends its entire life cycle in running water. While previously considered a distinct subspecies or even species, it is currently not considered to be taxonomically different from other ecological or migratory forms of the brown trout, i.e. the sea trout (Salmo trutta morpha trutta) or the lacustrine brown trout (Salmo trutta morpha lacustris).[2] The fario morph is often referred to as river trout in Europe. Riverine brown trout average 20 to 80 centimetres (7.9 to 31.5 in) but can reach lengths of 1 metre (3.3 ft). They usually attain a weight of up to 2 kilograms, but sometimes up to 13 kilograms (29 lb). Their back is olive-dark brown and silvery blue, red spots with light edges occur towards the belly, the belly itself is whitish yellow. They can live for up to 18 years.

Range

The native range of brown trout extends from northern Norway and White Sea tributaries in Russia in the Arctic Ocean to the Atlas Mountains in North Africa. The western limit of their native range is Iceland in the north Atlantic, while the eastern limit is in Aral Sea tributaries in Afghanistan and Pakistan.[3]

Introduction outside of their natural range

Brown trout have been widely introduced into suitable environments around the world, including North and South America, Australasia, Asia, and South and East Africa. Introduced brown trout have established self-sustaining, wild populations in many introduced countries.[4] The first introductions were in Australia in 1864 when 300 of 1500 brown trout eggs from the River Itchen survived a four-month voyage from Falmouth, Cornwall, to Melbourne on the sailing ship Norfolk. By 1866, 171 young brown trout were surviving in a Plenty River hatchery in Tasmania. Thirty-eight young trout were released in the river, a tributary of the River Derwent in 1866. By 1868, the Plenty River hosted a self-sustaining population of brown trout which became a brood source for continued introduction of brown trout into Australian and New Zealand rivers.[5] Successful introductions into the Natal and Cape Provinces of South Africa took place in 1890 and 1892, respectively. By 1909, brown trout were established in the mountains of Kenya. The first introductions into the Himalayas in northern India took place in 1868, and by 1900, brown trout were established in Kashmir and Madras.[6]

Introduction to Americas

The first introductions in Canada occurred in 1886 in Newfoundland and continued through 1933. The only Canadian regions without brown trout are the Yukon and Northwest Territories. Introductions into South America began in 1904 in Argentina. Brown trout are now established in Chile, Peru, and the Falklands.[5] In the 1950s and 1960s, Edgar Albert de la Rue, a French geologist, began the introduction of several species of salmonids on the remote Kerguelen Islands in the southern Indian Ocean. Of the seven species introduced, only brook trout, Salvelinus fontinalis, and brown trout survived to establish wild populations.[7] Sea-run forms of brown trout exceeding 20 lb (9.1 kg) are caught by local anglers on a regular basis.

Map of U.S. ranges of brown trout
U.S. range of brown trout

The first introductions into the U.S. started in 1883 when Fred Mather, a New York pisciculturist and angler, under the authority of the U.S. Fish Commissioner, Spencer Baird, obtained brown trout eggs from a Baron Lucius von Behr, president of the German Fishing Society. The von Behr brown trout came from both mountain streams and large lakes in the Black Forest region of Baden-Württemberg.[3] The original shipment of "von Behr" brown trout eggs were handled by three hatcheries, one on Long Island, the Cold Spring Hatchery operated by Mather, one in Caledonia, New York operated by pisciculturalist Seth Green, and other hatchery in Northville, Michigan. Additional shipments of "von Behr" brown trout eggs arrived in 1884. In 1885, brown trout eggs from Loch Leven, Scotland, arrived in New York. These "Loch Leven" brown trout were distributed to the same hatcheries. Over the next few years, additional eggs from Scotland, England, and Germany were shipped to U.S. hatcheries. Behnke (2007) believed all life forms of brown trout—anadromous, riverine and lacustine—were imported into the U.S. and intermingled genetically to create what he calls the American generic brown trout and a single subspecies the North European brown trout (S. t. trutta).[3]

In April 1884, the U.S. Fish Commission released 4900 brown trout fry into the Baldwin River, a tributary of the Pere Marquette River in Michigan. This was the first release of brown trout into U.S. waters. Between 1884 and 1890, brown trout were introduced into suitable habitats throughout the U.S.[3] By 1900, 38 states and two territories had received stocks of brown trout. Their adaptability resulted in most of these introductions establishing wild, self-sustaining populations.[5]

Depending on size and habitat, they feed mainly on insects and insect larvae that live in water, small fish such as bullheard, small crustaceans, snails and other water animals. Cannabalism has also been frequently observed among riverine brown 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

Riverine brown trout in aquarium

Riverine brown trout spawn between October and January in the northern hemisphere and between May and June in the southern hemisphere. The fish fan through rapid movements of the tail stock and caudal fin a shallow pit in the rock riverbed, into which about 1,000 to 1,500 reddish, four to five millimetre wide eggs are laid in several pits. The fish larvae emerge after two to four months.

Riverine brown trout has a special significances as a host fish for the glochidia of the freshwater pearl mussel.

Hybrids

The tiger trout (Salmo trutta fario × Salvelinus fontinalis) is a genetic cross between a riverine brown trout and a brook trout. 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 gonads. By contrast, male tiger trout develop testicles as well as secondary sex features such as kypes, humps, darker and thicker skin and a lighter fillet colouring during the spawning season.

Fishing

Well camouflaged riverine brown trout in a small stream
Riverine brown trout caught with the help of a fly

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

Riverine brown trout makes an excellent fish dish.

Angling

Riverine brown 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 riverine brown 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 insect. 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. In using wobblers and rubber fish care should be taken because they are banned on some waterbodies or may only be used with restrictions.

References

  1. ↑ Freyhof, J. (2012). "Salmo trutta". IUCN Red List of Threatened Species. Version 2012.1. International Union for Conservation of Nature. Retrieved 14 August 2012.
  2. ↑ Froese, Rainer and Pauly, Daniel, eds. (). "Salmo trutta" in FishBase. version.
  3. 1 2 3 4 Behnke, Robert J.; Williams, Ted (2007). "Brown Trout-Winter 1986". About Trout: The Best of Robert J. Behnke from Trout Magazine. Guilford, CT: Globe Pequot. pp. 45–50. ISBN 978-1-59921-203-6.
  4. ↑ "Global Invasive Species Database-Salmo trutta-Distribution". Invasive Species Specialist Group (ISSG) of the IUCN Species Survival Commission. Retrieved 2014-02-01.
  5. 1 2 3 Heacox, Cecil E. (1974). "Back Cast". The Complete Brown Trout. New York: Winchester Press. pp. 7–23. ISBN 0-87691-129-7.
  6. ↑ Newton, Chris (2013). "The Trout in India". The Trout's Tale - The Fish That Conquered an Empire. Ellesmere, Shropshire: Medlar Press. pp. 79–95. ISBN 978-1-907110-44-3.
  7. ↑ Newton, Chris (2013). "The Monsters of Kerguelen". The Trout's Tale - The Fish That Conquered an Empire. Ellesmere, Shropshire: Medlar Press. pp. 161–170. ISBN 978-1-907110-44-3.

Literature

Look up River trout in Wiktionary, the free dictionary.
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