All fish properly called trout are members opf the subfamily Salmoninae, but the name is used for fish from all three genera in the subfamily (Salmo, which includes Atlantic species, Oncorhynchus which includes Pacific species, and Salvelinus).
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, contributing to the displacement of native freshwater fish to some extent, though not as much as the carp.
Trout have no spines on the fins, 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 appearing populations show no significant genetic differences, and therefore what appear to be a large number of species are considered a much smaller number of distinct species by most ichthyologists. The trout found in the western United States are a good example of this. For example: the Brook Trout, the Aurora Trout and the extinct Silver Trout all have physical characteristics and colorations that distinguish them. Genetic analysis shows however that they are one species, Salvelinus fontinalis.
Some other fishes that are part of this group include the rainbow, lake, bull, and brown trouts.
Most trout are restricted to freshwater, but a few, like the steelhead (Oncorhynchus mykiss) - which is the same species as the landlocked rainbow trout - 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. Trouts generally feed on soft bodied invertebrates like worms, or insects, although larger specimen of brown trout regularily feed on other fish.
As a group, trout are a somewhat bony fish, but the flesh is considered good eating. Additionally, they provide a good fight when caught with a hook and line, and are sought after recreationally. Because of their popularity, trouts are often raised on fish farms and introduced into the streams that are most heavily fished. 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.
Kinds of trout include: the Brown Trout Salmo trutta, Rainbow Trout Oncorhynchus mykiss, Golden Trout Oncorhynchus mykiss aguabonita, Lahontan Cutthroat Trout Oncorhynchus clarki henshawi, and Eastern Brook Trout Salvelinus fontinalis.
|Rainbow Trout Oncorhynchus mykiss|
- 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