What are Trout?
The simple question: What is a Trout? seems simple enough, but as a commonly used, or even generic name for many fish or fishes around the world, the answer is a bit more complex. The Largemouth bass is referred to as a "Green Trout" in parts of the U.S. and the speckled trout ,a common saltwater species found in the Gulf of Mexico and member of the drum family, have adopted the trout name though they are not members of the Salmoninae family where the true "Trouts" are are derived.
The True Trout
Trout is a generic name given to the members of the Salmoninae or Salmonid family. Their isn't a direct scientific correlation with the name Trout and a specific group of Salmonids. Some of the individuals that have adopted the trout name fall into the Salvelinus (Charr) genus, Oncorhynchus (Pacific Salmon/Trout) genus, and the Salmo (Atlantic salmon/trout ) genus. The names Trout and Salmon are also used synonymously around the world when referring to some salmonid species. You can learn more about the Trout of the World in our articles on Salmon Species of the World, Trout Species of the World, and Char Species of the World.
Trout Facts
From the smallest mountains steams to the coastal estuaries of the Pacific and Atlantic Ocean, Trout occupy all varieties of water. While many associate small coldwater streams to the smaller, bug eating, adversaries willing to rise to a dry fly, others know trout as the aggressively predatory and cannibalistic fish willing to chase down a streamer in big water. The trout of these smaller streams often spend their entire lives in freshwater where they can live for around a decade in ideal conditions. Trout on some larger coastal rivers are capable of being anadromous (moving out to see returning to spawn). Here they can pack on substantial weight by feeding on the more abundant food resources in bays. Species such as brown trout, bull trout, brook trout, and the more well know steelhead (rainbow trout) use this high risk, high reward strategy to thrive in their home waters. During previous ice ages, it is thought that many more of these salmonids regularly visited their local estuaries before returning to their native streams to spawn like their salmon brethren.
What Do Trout Eat?
Most anglers know trout are usually bug eaters. Mayflies, Caddis Flies, and Stoneflies, are the major food items that comprise a large majority of most trout's diet. Other bugs such as midges, damselfies, and dragonflies often make their way on the menu alongside larger meals such as scuds, sowbugs, crayfish, and other fish species. You can learn more about the diets of trout and their salmon cousins in this article on What Trout Eat.
Where Do Trout Live?
Trout can be found across the Northern Hemisphere. From the Cherry Trout of Japan, to as far west as the Cutthroat Trout of the west coast of North America. Trout occupy the coldwater rivers, lakes, and streams of the world, and become stressed as water temperatures eclipse the 70 degree mark. Though trout are only native to the Northern Hemisphere, they have been stocked in the southern reaches of Africa, South America and Australia. Antarctica is the only continent where they are not currently found.
How Many Species of Trout Are There?
There are roughly 50 species of Salmonid found around the world. Of these species about 30 are referred to as trout. Several of these species such as the Brown Trout, Rainbow Trout, and Cutthroat Trout have a dozen or more named subspecies. Some of these subspecies can appear identical while others appear drastically different (typically in color). Genetically, many of these subspecies are not quite distinct enough to be referred to as a species by a consensus of biologists.
What is the Most Common Trout Species?
Rainbow trout are the most common trout species worldwide. They are currently stocked on every continent except for Antarctica thanks to their propensity for easy rearing in captivity. However, the Brown Trout has the largest native distribution of any member of the trout family, extending from the western streams of the Afghani Hindu-Kush to the coastal estuaries of Iceland.
What is the Rarest Trout Species?
The Green Trout of Morocco is likely to be the rarest trout species in the world. For decades this trout has battled extinction as it solely occupies one small lake in the middle Atlas Mountains. Other salmonids that face similar situations are the Fibreno Trout of Central Italy and a pair of taimen species (Sichuan Taimen and Korean Taimen) that have faced massive threats due to habitat loss and overharvesting.
Trout vs. Salmon
Maybe better asked: What are the differences between trout and salmon?
Trout and Salmon are general names given to the individual species of the Salmonid family. Some species such as the Cherry Trout/Cherry Salmon use both names. The name Salmon is generally used to refer to the Salmonid species that make their way to the Ocean for a portion of their life. This certainly doesn't mean trout species can't or won't make their way to a salt water environment at some point in there life. Other Salmonids such as the Danube Salmon/European Taimen use the salmon name and will never reach the sea. Members of the Char genus also use the trout name, such as the Brook Trout, Bull Trout, or Sunapee Trout. Overall both names are somewhat relative and lack any hard structure in classifying these species.
In adopting the generalization that salmon are the species that spend a large portion of lives at sea in order to grow to larger sizes while trout spend their lives in their river of origin. Salmon meat are often more lean due to the large journeys they make both at sea and upon returning to the rivers. They fight harder and for much longer durations pound for pound.