Trout
| Trout | ||||||||||||
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Brown trout ( Salmo trutta fario ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Salmo trutta | ||||||||||||
| Linnaeus , 1758 |
The trout ( Salmo trutta ) is a species of fish from the genus Salmo in the salmon family (Salmonidae). It occurs in the Atlantic , in the North and Baltic Seas , from Spain to Iceland and western Russia , and in many neighboring rivers and lakes in Europe . The species was also introduced by humans to the rest of Europe, North and South America, Africa, South Asia, Australia and New Zealand. According to the way of life, three forms are distinguished: the anadromous migratory sea trout as well as the forms of the lake trout and brown trout that remain in fresh water for life . Trout are popular sport fish , sea trout are also hunted with drift nets or used economically as bycatch .
The trout was named fish of the year in Germany in 2013 and in Switzerland in 2020 .
etymology
The German name "Forelle" has been proven in this form since the 16th century; it is derived from the Middle High German forhele from the Indo-European tribe perk- meaning “sprinkled, colorful” (see also southern German “Förche” in Förchensee ). The Latin name given by Carl von Linné in 1758 with the first scientific description in the Systema Naturæ combines the Latin words for salmon ( salmo ) and trout ( trutta ). The scientific name for the brown trout ( S. t. Fario ) is derived from an alternative Latin name for the trout, while that for the lake trout ( S. t. Lacustris ) refers to the way of life ( lacustris from lacus , “the lake ").
features
Trout have the typical spindle-shaped, laterally only moderately flattened body of salmon fish . They are more powerfully built than the closely related salmon ( Salmo salar ). The head is relatively large, the terminal mouth extends behind the eye and has strong teeth. In the male, it is deformed into a hook during the spawning season . The ploughshare has one or, especially in brown trout, two rows of teeth on the handle and two to six teeth on the plate. The gill trap has 14 to 16 thorns on the first arch, of which the top and bottom two to five are button-shaped and rod-shaped in between. The scales are generally small. Along the lateral line organ sit 120 to 130 round, overlapping scales, the size of which does not differ from those above and below. There are 13 to 16 scales between the lateral line and the adipose fin. The dorsal and pelvic fins are roughly in the middle of the body. The dorsal fin has 11 to 15 rays, the anal fin 9 to 14. The pectoral fins have 11 to 16, the pelvic fins 7 to 10 rays. The tail stalk is relatively high and laterally flattened. In smaller animals, the tail fin is slightly indented, in individuals over 20 centimeters in length it usually ends almost straight.
Adult sea and lake trout usually reach a length of 45 to 80 centimeters and a weight of 10 to 15 kilograms. However, sea trout can also reach just over a meter, lake trout even up to 140 centimeters in length and then up to 50 kilograms in weight. Brown trout usually only reach body lengths of 25 to 50 centimeters, more rarely up to 60 centimeters.
The coloration is very variable within the species and usually changes in the course of an animal's life, whereby it can slowly adapt to the color of the water bed. Adult animals are usually very dark blackish or brownish on the back, with a more or less light, whitish or yellowish-silvery belly. Young animals are usually lighter in color with shiny silver flanks. The basic color of brown trout is very variable and usually well adapted to the water surface. On the head and trunk, as well as the dorsal, adipose and caudal fins, there are numerous large, irregularly distributed blackish or brown spots that are sometimes surrounded by a light halo, well below the lateral line. Especially with brown trout, there are also red, light-rimmed points on the flanks. The number of spots increases with age. The adipose fin is usually orange or red in color or rimmed. Young fish under 10 centimeters in length also have dark transverse bands.
In trout and rainbow trout , effects of magnetic fields on the behavior were found; probably the animals of both species have a magnetic sense .
Way of life
There are both migratory forms of trout as well as forms that remain stationary in fresh water. In fresh water they prefer cold rivers, lakes and streams and feed mainly on aquatic insects, but also on flying insects. After one to five years, the migratory forms move into the sea with a length of 15 to 25 centimeters, where they live near the coast for half to five years, feed on crustaceans and small fish and grow up quickly. Adults migrate upstream from July to November. Like salmon, trout have a striking coloration during spawning. Between October and March, the females lay around 10,000 eggs on the bottom of the water and cover them with gravel. Most animals return to the sea after spawning.
Systematics
The trout was scientifically described by Carl von Linné in his work Systema Naturae as Salmo trutta in 1758, describing the various forms as subspecies . The sea trout was named Salmo trutta trutta as a nominotypical taxon , the lake trout was referred to as Salmo trutta lacustris and the brown trout as Salmo trutta fario . However, since the three forms are not clearly separated from one another in terms of distribution, reproduction or their characteristics, this classification is mostly rejected today. The sea trout is therefore often referred to as " Salmo trutta forma trutta " or " Salmo trutta morpha trutta " and the other forms analogously, which is not a valid designation according to the International Rules for Zoological Nomenclature .
The exact extent of the species Salmo trutta as well as a possible subdivision into subspecies is still controversial today, depending on which database and which species concept are used. A current revision of the genus Salmo is not available. Taxonomic investigations are made more difficult by the diversity of forms within the populations, but in particular also by the stocking of different bodies of water with farmed trout, whereby the price and not the origin is usually decisive for the selection of the animals, so that the original distribution areas can in some cases no longer be reconstructed . According to molecular biological and morphological investigations, it is certain that within the genus Salmo the Atlantic salmon is opposed to the rest of the genus, which in turn can be divided into two lines, one of which is two species occurring in the Balkans (the Adriatic trout ( Salmo obtusirostris ) and Salmo ohridanus ) and the other the rest, i.e. Salmo trutta in the broader sense.
Within this last group, three or four groups can be distinguished, which some authors regard as subspecies. Then between the Atlantic sea trout ( Salmo trutta trutta ), along the Atlantic coast and in the waters of Northern and Western Europe, the Black Sea trout ( Salmo trutta labrax ), which has a higher number of gill thorns and occurs in the Black Sea and its tributaries, is the larger Caspian trout ( Salmo trutta caspius ), in the area of the Caspian Sea, and the Mediterranean brown trout ( Salmo trutta macrostigma ), which occurs in parts of Italy and the adjoining western archipelago , are distinguished. According to the system used here according to Kottelat and Freyhof , the species Salmo trutta only includes the Atlantic sea trout and the freshwater forms derived from it, while the other Salmo populations are assigned to other species.
Web links
- Trout on Fishbase.org (English)
Individual evidence
- ↑ a b Salmo trutta in the endangered Red List species the IUCN 2009 Posted by: J. Freyhof, M. Kottelat, 2008. Accessed July 18 of 2009.
- ↑ a b c d e f B.J. Muus: marine fish from the Baltic Sea, the North Sea, the Atlantic . 5th edition. BLV, Munich 1985, ISBN 3-405-11861-1 , p. 78-79 .
- ↑ Overview "Fish of the Year" in Germany. German Fishing Association, accessed on February 26, 2018 .
- ↑ Fisheries Association declares trout Fish of the Year 2020. In: swissinfo.ch . January 2, 2020, accessed January 2, 2020 .
- ↑ Regina Petz-Glechner: The names of our fish - an etymological search for traces . In: Federal Institute for Water Research and Fisheries Management (Hrsg.): Österreichs Fischerei . tape (57) 7 , 2004, ISSN 0029-9987 , ZDB -ID 544963-7 , 8. Forellen, p. 170–172 ( PDF, 35 kB [accessed June 15, 2011] 3 pages). PDF, 35 kB ( Memento of the original from January 31, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b Uwe Hartmann: Freshwater fish . 2nd Edition. Ulmer, Stuttgart (Hohenheim) 2002, ISBN 3-8001-4296-1 , p. 34-37 .
- ↑ a b Maurice Kottelat, Jörg Freyhof: Handbook of European Freshwater Fishes . Berlin 2007, ISBN 978-2-8399-0298-4 , pp. 408-412 .
- ↑ a b c Roland Gerstmeier, Thomas Romig: The freshwater fish of Europe for nature lovers and anglers . 2nd Edition. Franckh-Kosmos, Stuttgart 2003, ISBN 3-440-09483-9 , pp. 305-308 .
- ↑ Salmo trutta lacustris at Fishbase
- ↑ Krzysztof Formicki et al .: Spatial orientation of trout (Salmo trutta L.) and rainbow trout (Oncorhynchus mykiss Walb.) Embryos in natural and artificial magnetic fields. In: Acta Ichthyologica et Piscatoria. Volume 27, No. 2, 1997, pp. 29-40, doi: 10.3750 / AIP1997.27.2.03 .
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