Trout is the common name given to a number of species of freshwater fish belonging to the Salmonidae family.
All fish called trout are members of the subfamily Salmonidae
. The name is commonly used for species in three of the seven genera
in the sub-family: Salmo
,which includes fish also sometimes called char
, Fish referred to as trout include:
- Genus Salmo
- Genus Oncorhynchus
- Apache trout, Oncorhynchus Apache
- Eskimo trout, Oncorhynchus inupiat
- Seema, Oncorhynchus masou
- Cutthroat trout, Oncorhynchus clarki
The cutthroat trout has 14 recognized subspecies (depending on your sources), such as the Lahontan cutthroat trout, Oncorhynchus clarki henshawi, Bonneville cutthroat trout, Oncorhynchus clarki utah, Colorado River cutthroat trout, Yellowstone cutthroat trout.
- Gila trout, Oncorhynchus gilae
- Golden trout, Oncorhynchus aguabonita
- Rainbow trout, Oncorhynchus mykiss
- Mexican Golden Trout, Oncorhynchus chrysogaster and as many as eight other species or sub-species in northwest Mexico, not yet formally named.
- Genus Salvelinus (Char)
Trout are usually found in cool (50-60°F, 10-15°C), clear streams and lakes, although many of the species have anadromous strains as well. Young trout are referred to as troutlet or troutling. They 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 and endangering several upland native fish species. The introduced species included brown trout from England and rainbow trout from California. The rainbow trout were a steelhead strain, generally accepted as coming from Sonoma Creek. The rainbow trout of New Zealand still show the steelhead tendency to run up rivers in winter to spawn. The speckled trout, found in the Gulf of Mexico and other places in the United States, is not in fact a trout at all, but a member of the drum family.
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 markings and more vivid coloration; it is also possible that in some species this signifies that they are ready to mate. 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.
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, since many of these distinct populations show no significant genetic differences, 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 colorations that distinguish them, yet genetic analysis shows that they are one species, Salvelinus fontinalis.
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 lifespan of 7 years. Lake trout can live many decades, and can grow to more than .
Understanding how moving water shapes the stream channel will improve your chances of finding trout. In most streams, the current creates a Riffle-Run-Pool pattern that repeats itself over and over. A deep pool may hold a big brown trout
, but rainbows and smaller browns are likely found in runs. Riffles are where you will find small trout, called troutlet, during the day and larger trout crowding in during morning and evening feeding periods.
- Riffles have a fast current and shallow water. This gives way to a bottom of gravel, rubble or boulder. Riffles are morning and evening feeding areas. Trout usually spawn just above or below riffles, but may spawn right in them.
- Runs are deeper than riffles with a moderate current and are found between riffles and pools. The bottom is made up of small gravel or rubble. These hot spots hold trout almost anytime, if there is sufficient cover.
- Pools are smoother and look darker than the other areas of the stream. The deep, slow-moving water generally has a bottom of silt, sand, or small gravel. Pools make good midday resting spots for medium to large trout.
As a group, trout are somewhat bony, but the flesh is generally considered to be appetizing. Additionally, they provide a good fight when caught with a hook
, 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 and Salmon of North America, Robert J. Behnke, Illustrated by Joseph R. Tomelleri, The Free Press, 2002, hardcover, 359 pages, ISBN 0-7432-2220-2
- Trout Science, , 2000, knowledgebase article