Brown trout profile



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Brown trout

From Wikipedia, the free encyclopediaBrown troutFlyfishingthings.com/Brown TroutConservation status
Least Concern (IUCN 3.1)[1]Scientific classificationKingdom:AnimaliaPhylum:ChordataClass:ActinopterygiiOrder:SalmoniformesFamily:SalmonidaeGenus:SalmoSpecies:Salmo truttaBinomial nameSalmo trutta
Linnaeus,1758Morphs

Salmo trutta morpha trutta
Salmo trutta morpha fario
Salmo trutta morpha lacustris

The brown trout (Salmo trutta) is an originallyEuropean species ofsalmonid fish. It includes both purely freshwater populations, referred to Salmo truttamorpha fario and S. trutta morpha lacustris, andanadromous forms known as the sea trout, S. trutta morpha trutta. The latter migrates to theoceans for much of its life and returns to freshwater only tospawn.[2] Sea trout in the UK and Ireland have many regional names, including sewin (Wales), finnock (Scotland), peal (West Country), mort (North West England) and white trout (Ireland).

Thespecific epithet trutta derives from theLatin trutta, meaning, literally, “trout“.

Thelacustrinemorph of brown trout is most usuallypotamodromous, migrating from lakes into rivers or streams to spawn, although evidence indicates stocks spawn on wind-swept shorelines of lakes. S. trutta morphafario forms stream-resident populations, typically in alpine streams, but sometimes in larger rivers. Anadromous and nonanadromous morphs coexisting in the same river appear not to be genetically distinct.[3] What determines whether or not they migrate remains unknown.

Range

The brown trout is normally considered to be native to Europe, but the natural distribution of the migratory forms may be, in fact, circumpolar.[citation needed] Landlocked populations also occur far from the oceans, for example inGreece andEstonia.

Conservation status

The fish is not considered to beendangered, although, in some cases, individualstocks are under various degrees of stress mainly through habitat degradation,overharvest and artificial propagation leading tointrogression. Increased frequency of excessively warm water temperatures in high summer causes a reduction in dissolvedoxygen levels which can cause ‘summer kills’ of local populations if temperatures remain high for sufficient duration and deeper/cooler or fast, turbulent moreoxygenated water is not accessible to the fish. This phenomenon can be further exacerbated byeutrophication of rivers due topollution – often from the use of agriculturalfertilizers within thedrainage basin.

Overfishing is a problem whereanglers fail to identify and return mature female fish into the lake or stream. Each large female removed can result in thousands fewer eggs released back into the system when the remaining fish spawn.

Another threat is other introducedorganisms. For example inCanada‘sBow River, a non-nativealga Didymosphenia geminata – common namerock snot (due to appearance) – has resulted in reduced circulation of water amongst the substrate of the river bed in affected areas. This, in turn, can greatly reduce the number of trout eggs which survive to hatch. Over time, this leads to reduction of the population of adult fish in the areas affected by the algae, forming a circle of decline. Rock snot is believed to have spread accidentally on the soles of the footwear of visitors from areas where the alga is native. The wide variety of issues that adversely affect brown trout throughout its range do not exclusively affect brown trout, but affect many or all species within a water body, thus altering theecosystem in which the trout reside.[citation needed]

In small streams, brown trout are important predators ofmacroinvertebrates, and declining brown trout populations in these specific areas would affect the entire aquaticfood web.[4]S. trutta morpha fario prefers cold (though in comparison with other “trout”, this species has a somewhat higher temperature preference of about 60-65°F, or 15.5-18.3°C), and well-oxygenated upland waters, especially large streams in mountainous areas.

Cover or structure is important to trout, and they are more likely to be found near submerged rocks & logs, undercut banks, and overhanging vegetation. Structure provides protection from predators, bright sunlight, and higher water temperatures. Access to deep water for protection in winter freezes, or fast water for protection from low oxygen levels in summer are also ideal. Trout are more often found in heavy and strong currents.

Characteristics

Flyfishingthings.com/Brown trout caught fly fishing.A 2.7-kg, 60-cm sea trout, fromGalway Bay in the West ofIreland bearing scars from afishing netFlyfishingthings.com/Waxworms as brown trout  bait.Waxworms are used aslive-bait for trout fishing.Flyfishingthings.com/Brown trout  bait corn worms.Corn worms are also excellentlive-bait when trout fishing.Flyfishingthings.com/Femail Brown trout.A young brown trout from theRiver Derwent inNorth East EnglandFlyfishingthings.com/beautiful brown trout.Brown trout from a westernWyoming creekFlyfishingthings.com/Brown trout in stream.Brown trout in a creekFlyfishingthings.com/Brown trout fry.Brown trout inVärmland,Sweden, after the first summer

The brown trout is a medium-sized fish, growing to 20 kg or more and a length of about 100 cm in some localities, although in many smaller rivers, a mature weight of 1 kg (2 lb) or less is common. Salmo trutta lacustris reaches an average length of 40-80 cm (16-32 inches) with a maximum length of 140 cm (55 inches) and about 60 pounds (27.2 kg). The spawning behaviour of brown trout is similar to that of the closely relatedAtlantic salmon. A typical female produces about 2,000 eggs per kilogram (900 eggs per pound) of body weight at spawning. On Sept. 11, 2009, a 41.45-lb (18.80-kg) brown trout was caught by Tom Healy in theManistee River system inMichigan, setting a new state record. As of late December 2009, the fish captured by Mr. Healy was confirmed by both the International Game Fish Association and the Fresh Water Fishing Hall of Fame as the new all-tackle world record for the species. This fish now supplants the former world record from the Little Red River in Arkansas.

Brown trout can live to ages of 20 years. But as with the Atlantic salmon, a high proportion of males die after spawning, and probably fewer than 20% of anadromous female kelts recover from spawning. The migratory forms grow to significantly larger sizes for their age due to abundant forage fish in the waters where they spend most of their lives. Sea trout are more commonly female in less nutrient rich rivers. Brown trout are active both by day and by night and are opportunistic feeders. While in fresh water, their diets will frequently include invertebrates from thestreambed, other fish,frogs, mice, birds, and insects flying near the water’s surface. The high dietary reliance upon insect larvae, pupae, nymphs and adults is what allows trout to be a favoured target forfly fishing. Sea trout are especially fished for at night usingwet flies. Brown trout can be caught withlures such as spoons, spinners, jigs, plugs, plastic worm imitations, and live or deadbaitfish. Freshwater brown trout range in colour from largely silver with relatively few spots and a white belly, to the more well-known brassy brown cast fading to creamy white on the fish’s belly, with medium-sized spots surrounded by lighter halos. The more silver forms can be mistaken for rainbow trout. Regional variants include the so-called “Loch Leven” trout, distinguished by larger fins, a slimmer body, and heavy black spotting, but lacking red spots. The continental European strain features a lighter golden cast with some red spotting and fewer dark spots. Notably, both strains can show considerable individual variation from this general description. Early stocking efforts in the United States used fish taken fromScotland andGermany. The Loch Leven strain is more often found in the western United States, while the “German brown” is found more toward the Midwest and East.

Brown trout rarely formhybrids with other species; if they do, they are almost invariably infertile. One such example is thetiger trout, a hybrid with thebrook trout.

Diet

Field studies have demonstrated that brown trout fed on several animal preys, aquatic invertebrates being the most abundant prey items. However, brown trout also feed on other taxa such as terrestrial invertebrates (e.g. Hymenoptera) or fishes.[5] Moreover, in brown trout, as in many other fish species, there is normally a change in the diet composition during the life of the fish,[6] and piscivorous behaviour is most frequent in large brown trout.[7] These shifts in the diet during fish life stage transitions may be accompanied by a marked reduction in intra-specific competition in the fish population, facilitating the partitioning of resources.[8][9]

First feeding of newly emerged fry is very important for brown trout survival in this phase of the life cycle, and in newborns of brown trout first feeding can occur even prior to emergence.[10][11] Newborns start to feed before complete yolk absorption and the diet composition of newly emerged brown trout is composed by small prey such as chironomid larvae or baetid nymphs.[12]

Stocking, farming and non-native brown trout

Flyfishingthings.com/Brown trout stamp.Brown trout (Salmo trutta fario) in aFaroese stamp issued in 1994

The species has been widelyintroduced forsport fishing intoNorth America,South America,Australia,New Zealand and many other countries, includingBhutan, where they are the focus of a specialised fly fishery. First planting in the United States occurred April 11, 1884 into the Baldwin River, one mile east ofBaldwin, MI.[13] Brown trout have had serious negative impacts onupland native fish species in some of the countries where they have been introduced, particularly Australia. Because of the trout’s importance as a food and game fish, it has beenartificially propagated and stocked in many places in its range, and fully natural populations (uncontaminated byallopatricgenomes) probably exist only in isolated places, for example inCorsica or in high alpine valleys on the European mainland.

Farming of brown trout has included the production of infertiletriploid fish by increasing the water temperature just after fertilisation of eggs, or more reliably by a process known as pressure shocking. Triploids are favoured byanglers because they grow faster and larger thandiploid trout. Proponents of stocking triploids argue, because they are infertile, they can be introduced into an environment that contains wild brown trout without the negative effects of cross-breeding. However, stocking triploids may damage wild stocks in other ways. Triploids certainly compete with diploid fish for food, space and other resources. They could also be more aggressive than diploid fish and they may disturb spawning behaviour.

Scottish and Irish sea trout populations in recent years have seriously declined, possibly due to infestation bysea lice from salmon farms.[14]

 

 

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