Trout are usually found in cool, clear
streams and lakes, and are distributed naturally throughout North
America, northern Asia and Europe. Several species of trout were
introduced to Australia and New Zealand by amateur fishing enthusiasts
in the 19th century, effectively displacing several upland native
Trout have fins entirely without spines, and all of them have a
small adipose (fatty) fin along the back, near the tail. There are
many species, and even more populations that are isolated from each
other and morphologically different. However, many of these distinct
populations show no significant genetic differences, and therefore
what may appear to be a large number of species is considered a
much smaller number of distinct species by most ichthyologists.
The trout found in the eastern United States are a good example
of this. The brook trout, the aurora trout and the (extinct) silver
trout all have physical characteristics and colourations that distinguish
them, yet genetic analysis shows that they are one species, Salvelinus
Lake trout (Salvelinus namaycush), like brook trout, actually belong
to the char genus. Lake trout inhabit many of the larger lakes in
North America and live much longer than rainbow trout which have
an average maximum life span of 7 years. Lake trout can live many
decades and can grow to more than 60 pounds (27 kg).
Most trout are restricted to fresh water, but many spend their
adult life in the ocean and then return to spawn in the streams
in which they were hatched. This is called anadromous reproduction
and is more often seen in salmon. Brook trout, brown trout, cutthroat
trout, bull trout, and Arctic char also have populations that run
to salt water.
Trout generally feed on soft bodied aquatic invertebrates, such
as Diptera, mayfly, caddis fly, and stonefly, although larger specimens
of trout regularly feed on other fish.
As a group, trout are somewhat bony, but the flesh is generally
considered to be tasty. Additionally, they provide a good fight
when caught with a hook and line, and are sought after recreationally.
Because of their popularity, trout are often raised on fish farms
and planted into heavily fished waters in an effort to mask the
effects of overfishing. While they can be caught with a normal rod
and reel, fly fishing is a distinctive method developed primarily
for trout and now extended to other species. Farmed trout and char
are also sold commercially as food fish.
Trout that live in different environments can have dramatically
different colorations and patterns. Mostly, these colors and patterns
form as camouflage, based on the surroundings, and will change as
the fish moves to different habitats. Trout in, or newly returned
from the sea, can look very silvery, while the same "genetic"
fish living in a small stream or in an alpine lake could have pronounced
greenish speckles with far more coloration. It is virtually impossible
to define a particular color pattern as belonging to a specific
breed, however, in general, wild fish are claimed to have more vivid
colors and patterns.
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