Everything about The Brown Trout totally explained
The
brown trout (
Salmo trutta morpha
fario and
S. trutta morpha
lacustris) and the
sea trout (
S. trutta morpha
trutta) are
fish of the same species.
They are distinguished chiefly by the fact that the brown trout is largely a
freshwater fish, while the sea trout shows
anadromous reproduction, migrating to the
oceans for much of its life and returning to freshwater only to
spawn.
The
lacustrine morph of brown trout is most usually
potamodromous, migrating from lakes into rivers or streams to spawn, although there's some evidence of stocks that spawn on wind-swept shorelines of lakes.
S. trutta morpha
fario form stream-resident populations, typically in alpine streams but sometimes in larger rivers. There is evidence that anadromous and non-anadromous morphs coexisting in the same river can be genetically identical. In common usage, the name "brown trout" is often applied indiscriminately to the various morphs.
The brown trout is normally considered to be native to
Europe and
Asia but the natural distribution of the migratory forms may be, in fact, circumpolar. There are also landlocked populations far from the oceans, for example in
Greece and
Estonia. The fish isn't considered to be
endangered although, in some cases, individual
stocks are under various degrees of stress mainly through habitat degradation,
overharvest and artificial propagation leading to
introgression.
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), well-
oxygenated upland waters, especially large streams in mountainous areas. Cover is important to trout, and they're more likely to be found where there are submerged rocks, undercut banks, and overhanging vegetation.
The brown trout is a medium sized fish, growing to 20
kg or more in some localities although in many smaller rivers a mature weight of 1 kg (2 lb) or less is common. The current International Game Fish Association (IGFA) world "all tackle" record brown trout, 18.25 kg (40 pounds, 4 ounces), was caught in May 1992 from the
Little Red River,
Arkansas by Howard "Rip" Collins.
Brown trout may live for several years but, as with the
Atlantic salmon, there's a high proportion of death of males after spawning and probably fewer than 20% of female kelts recover from spawning. The migratory forms grow to significantly larger sizes and may live longer. Brown trout are active both by day and by night and are opportunistic feeders. While in fresh water, the diet will frequently include invertebrates from the
streambed, small fish,
frogs, 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 for
fly fishing. Sea trout are especially fished for at night using
wet flies.
The spawning behaviour of brown trout is similar to that of the closely related Atlantic salmon. A typical female produces about 2,000 eggs per kilogram (900 eggs per pound) of body weight at spawning. Brown trout rarely form hybrids, almost invariably infertile, with other species. One such example is the
tiger trout, a hybrid with the
brook trout.
Trout is a favourite
food fish, and is used both fresh and smoked; there are many
recipes for it, and it may be eaten fried, grilled, baked, cured or
microwaved.
The
specific epithet
trutta derives from the
Latin trutta, meaning, literally, "trout".
Stocking, farming and non-native brown trout
The species has been widely
introduced for purposes of
sport into
North America,
South America,
Australia and
New Zealand. Brown trout have had serious negative impacts on
upland native fish species in some of the countries where they've been introduced, particularly Australia. Because of the trout's importance as a food and game fish, it has been
artificially propagated and stocked in many places in its range, and fully natural populations (uncontaminated by
allopatric genomes) probably exist only in isolated places, for example in
Corsica or in high alpine valleys on the European mainland.
Farming of brown trout has included the production of infertile
triploid fish by increasing the water temperature just after fertilisation of eggs, or more reliably by a process known as pressure shocking. Triploids are favoured by
anglers because they grow faster and larger than
diploid trout. Proponents of the stocking of triploids argue that, because they're infertile, they can be introduced into an environment that contains wild brown trout without the negative effects of cross-breeding. However, it's possible that 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.
Sea trout populations in recent years have seriously declined due to infestation by
sea lice from salmon farms.
Further Information
Get more info on 'Brown Trout'.
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