Rainbow trout
Overview
 
The rainbow trout is a species of salmonid native to tributaries of the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. The steelhead is a sea run rainbow trout (anadromous) usually returning to freshwater to spawn after 2 to 3 years at sea. In other words, rainbow trout and steelhead trout are the same species. The fish are often called salmon trout. Several other fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 in the salmonid family are called trout
Trout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

, some are anadromous like salmon, whereas others are resident in freshwater only.

The species has been introduced for food or sport to at least 45 countries, and every continent except Antarctica.
Encyclopedia
The rainbow trout is a species of salmonid native to tributaries of the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. The steelhead is a sea run rainbow trout (anadromous) usually returning to freshwater to spawn after 2 to 3 years at sea. In other words, rainbow trout and steelhead trout are the same species. The fish are often called salmon trout. Several other fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 in the salmonid family are called trout
Trout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

, some are anadromous like salmon, whereas others are resident in freshwater only.

The species has been introduced for food or sport to at least 45 countries, and every continent except Antarctica. In some locations, such as Southern Europe
Southern Europe
The term Southern Europe, at its most general definition, is used to mean "all countries in the south of Europe". However, the concept, at different times, has had different meanings, providing additional political, linguistic and cultural context to the definition in addition to the typical...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, they have negatively impacted upland
Upland and lowland (freshwater ecology)
In studies of the ecology of freshwater rivers, habitats are classified as upland and lowland.-Definitions:Upland habitats are cold, clear, rocky, fast flowing rivers in mountainous areas; lowland habitats are warm, slow flowing rivers found in relatively flat lowland areas, with water that is...

 native fish species, either by eating them, outcompeting them, transmitting contagious diseases, (like Whirling disease transmitted by Tubifex
Tubifex
Tubifex is a cosmopolitan genus of tubificid Annelids that inhabit the sediments of lakes, rivers and occasionally sewer lines. There are over ten known species of Tubifex, but the number is not certain, as the species are not easily distinguishable from each other.-Food and feeding:Tubifex worms...

) or hybridization with closely related species and subspecies that are native to western North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

.

Taxonomy

The species was originally named by Johann Julius Walbaum
Johann Julius Walbaum
Johann Julius Walbaum was a physician, naturalist and taxonomist. He was the first to describe many previously unknown species from remote parts of the globe, such as the Great Barracuda , the Chum salmon from the Kamchatka River in Siberia, and the curimatá-pacú Johann Julius Walbaum (30 June...

 in 1792 based on type specimens from Kamchatka. Richardson named a specimen of this species Salmo gairdneri in 1836, and in 1855, W. P. Gibbons found a population and named it Salmo iridia, later corrected to Salmo irideus, however these names faded once it was determined that Walbaum's type description was conspecific and therefore had precedence (see e.g. Behnke, 1966). More recently, DNA studies showed rainbow trout are genetically closer to Pacific salmon (Onchorhynchus species) than to brown trout
Brown trout
The brown trout and the sea trout are fish of the same species....

 (Salmo trutta) or Atlantic Salmon
Atlantic salmon
The Atlantic salmon is a species of fish in the family Salmonidae, which is found in the northern Atlantic Ocean and in rivers that flow into the north Atlantic and the north Pacific....

 (Salmo salar), so the genus was changed.

Unlike the species' former name's epithet iridia , the specific
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 epithet mykiss derives from the local Kamchatkan name 'mykizha'; all of Walbaum's species names were based on Kamchatkan local names.

The ocean going (anadromous) form (including those returning for spawning) are known as steelhead, (Canada and the United States) or ocean trout (Australia), although they are the same species.

Life cycle

Like salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...

, steelhead are anadromous: they return to their original hatching ground to spawn
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

. Similar to Atlantic salmon
Atlantic salmon
The Atlantic salmon is a species of fish in the family Salmonidae, which is found in the northern Atlantic Ocean and in rivers that flow into the north Atlantic and the north Pacific....

, but unlike their Pacific Oncorhynchus
Oncorhynchus
Oncorhynchus is a genus of fish in the family Salmonidae; it contains the Pacific salmons and Pacific trouts. The name of the genus is derived from the Greek onkos and rynchos , in reference to the hooked jaws of males in the mating season .-Range:Salmon and trout with ranges generally in waters...

salmonid kin, steelhead are iteroparous (able to spawn several times, each time separated by months) and make several spawning trips between fresh and salt water. The steelhead smolt
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

s (immature or young fish) remain in the river for about a year before heading to sea, whereas salmon typically return to the seas as smolts. Different steelhead populations migrate
Fish migration
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...

 upriver at different times of the year. "Summer-run steelhead" migrate between May and October, before their reproductive organs are fully mature. They mature in freshwater before spawning in the spring. Most Columbia River
Columbia River
The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...

 steelhead are "summer-run". "Winter-run steelhead" mature fully in the ocean before migrating, between November and April, and spawn shortly after returning. The maximum recorded life-span for a rainbow trout is 11 years.

Feeding

Rainbow trout are predators with a varied diet, and will eat nearly anything they can grab. Their image as a selective eater is only a legend. Rainbows are not quite as piscivorous or aggressive as brown trout
Brown trout
The brown trout and the sea trout are fish of the same species....

 or lake trout (char)
Salvelinus
Salvelinus is a genus of salmonid fish often called char or charr; some species are called "trout". Salvelinus is a member of the Salmoninae subfamily of the Salmonidae family. Charr may be identified by light cream pink or red spots over a darker body. Scales tend to be small, with 115-200 along...

. Young rainbows survive on insects, fish eggs, smaller fish (up to 1/3 of their length), along with crayfish and other crustaceans. As they grow, though, the proportion of fish increases in most all populations. Some lake dwelling lines may become plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

ic feeders. While in flowing waters populated with salmonids, trout eat varied fish eggs, including salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...

, cutthroat trout
Cutthroat trout
The cutthroat trout is a species of freshwater fish in the salmon family of order Salmoniformes. It is one of the many fish species colloquially known as trout...

, as well as the eggs of other rainbow trout, alevin, fry, smolt
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

 and even left-over carcasses.

Length and Weight

As rainbow trout grow, they lengthen and increase in mass. The relationship between length and mass is not linear. The relationship between total length (L, in inches) and total mass (W, in pounds) for steelhead and nearly all other fish can be expressed by an equation of the form:

b is close to 3.0 for all species, and c is a constant that varies among species. For lentic rainbow trout, b = 2.990 and c = 0.000426, and for lotic rainbow trout, b = 3.024 and c = 0.000370.

The relationship described in this section suggests that a 13 in (33 cm) lentic rainbow trout weighs about 1 lb (0.45359237 kg), while an 18 in (45.7 cm) lentic rainbow trout weighs about 2.5 lb (1.1 kg).

Threats and conservation

Steelhead trout populations have declined due to human and natural causes. Steelhead (Oncorhynchus mykiss) historically occurred around the North Pacific Ocean from northwestern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 in North America to eastern Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 in Asia.

Two West Coast Evolutionarily Significant Units (ESUs) are endangered under the Federal Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

 (Southern California
Southern California
Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...

 and Upper Columbia River
Columbia River
The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...

) and eight ESUs are threatened. The U.S. National Marine Fisheries Service
National Marine Fisheries Service
The National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...

 has a detailed description of threats. Southern California (south of Point Conception
Point Conception
Point Conception is a headland along the Pacific coast of U.S. state of California, located in southwestern Santa Barbara County. It is the point where the Santa Barbara Channel meets the Pacific Ocean, and as the corner between the mostly north-south trending portion of coast to the north and the...

) ESU steelhead have been affected by habitat loss due to dams, confinement of streams in concrete channels, water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....

, groundwater pumping, urban heat island
Urban heat island
An urban heat island is a metropolitan area which is significantly warmer than its surrounding rural areas. The phenomenon was first investigated and described by Luke Howard in the 1810s, although he was not the one to name the phenomenon. The temperature difference usually is larger at night...

 effects, and other byproducts of urbanization
Urbanization
Urbanization, urbanisation or urban drift is the physical growth of urban areas as a result of global change. The United Nations projected that half of the world's population would live in urban areas at the end of 2008....

.

Several studies have shown that almost all California coastal steelhead are of native origin, despite over a century of hatchery stocking. Genetic analysis shows that South Central California Coast (SCCC) Distinct population segment
Distinct population segment
A distinct population segment is the smallest division of a taxonomic species permitted to be protected under the U.S. Endangered Species Act. Species, as defined in the Act for listing purposes, is a taxonomic species or subspecies of plant or animal, or in the case of vertebrate species, a...

 (DPS) and Southern California (SC) DPS from Malibu Creek
Malibu Creek
Malibu Creek is a year-round stream in western Los Angeles County, California. It drains the southern Simi Hills and the westernmost San Fernando Valley, flows south through the Santa Monica Mountains, and enters Santa Monica Bay east of Malibu. The Malibu Creek watershed drains and its tributary...

 north, and including the San Gabriel River
San Gabriel River (California)
The San Gabriel River flows through southern Los Angeles County, California in the United States. Its main stem is about long, while its farthest tributaries extend almost altogether...

, Santa Ana River
Santa Ana River
The Santa Ana River is the largest river of Southern California in the United States. Its drainage basin spans four counties. It rises in the San Bernardino Mountains and flows past the cities of San Bernardino and Riverside, before cutting through the northern tip of the Santa Ana Mountains and...

 and San Mateo Creek
San Mateo Creek (Southern California)
San Mateo Creek is a stream in Southern California in the United States, whose watershed mostly straddles the border of Orange and San Diego Counties. It is about long, flowing in a generally southwesterly direction...

, are not hatchery strains. However, steelhead from Topanga Creek and the Sweetwater River
Sweetwater River (California)
The Sweetwater River is a long stream in southwestern California in the United States. From its headwaters high in the Cuyamaca Mountains, the river flows generally southwest, first through rugged hinterlands but then into the urban areas surrounding its mouth at San Diego Bay. Its drainage basin...

 were partly, and from San Juan Creek
San Juan Creek
San Juan Creek, also called the San Juan River, is a stream in Orange County, California that consists of a catchment basin encompassing . Its mainstem rises in the Santa Ana Mountains, in the Trabuco Ranger District of the Cleveland National Forest...

 completely, of hatchery origin. Genetic analysis has also shown that steelhead in the streams of the Santa Clara County and Monterey Bay
Monterey Bay
Monterey Bay is a bay of the Pacific Ocean, along the central coast of California. The bay is south of San Francisco and San Jose, between the cities of Santa Cruz and Monterey....

 basins are not of hatchery origin, including the Coyote Creek, Guadalupe River
Guadalupe River (California)
The Guadalupe River is a short river in California whose headwater creeks originate in the Santa Cruz Mountains near the summit of Loma Prieta and Mount Umunhum. The river mainstem now begins on the Santa Clara Valley floor at the northern end of Lake Almaden, which is fed by Los Alamitos Creek and...

, Pajaro River
Pajaro River
The Pajaro River is a river in Northern California, forming part of the border between Santa Cruz County and Monterey County and between San Benito County and Santa Clara County.-History:...

, Permanente Creek
Permanente Creek
Permanente Creek is a stream originating on Black Mountain in Santa Clara County, California, United States. It is the namesake for the Kaiser Permanente health maintenance organization...

, Stevens Creek, San Francisquito Creek
San Francisquito Creek
San Francisquito Creek is a creek that flows into southwest San Francisco Bay in California, United States of America. Historically it was called the Arroyo de San Francisco by Juan Bautista de Anza in 1776...

, San Lorenzo River
San Lorenzo River
The San Lorenzo River drains a large watershed in Santa Cruz County, California. The headwaters originate in the Santa Cruz Mountains at an elevation of , and the river flows through the San Lorenzo Valley before emptying into the Pacific Ocean at Monterey Bay...

, and San Tomas Aquino Creek
San Tomas Aquino Creek
San Tomas Aquinas Creek, known locally as San Tomas Aquino Creek, is a stream that heads on El Sereno mountain in El Sereno Open Space Preserve in Saratoga, California in Santa Clara County, California, United States...

 basins. Natural waterfalls and two major dams have isolated Russian River
Russian River (California)
The Russian River, a southward-flowing river, drains of Sonoma and Mendocino counties in Northern California. With an annual average discharge of approximately , it is the second largest river flowing through the nine county Greater San Francisco Bay Area with a mainstem 110 miles ...

 anadromous steelhead from its non-ocean going rainbow trout form above the impassable barriers, however a recent genetic study of fin samples collected from steelhead at 20 different sites both above and below passage barriers in the watershed found that despite the fact that 30 million hatchery trout were stocked in the river from 1911 to 1925, the steelhead remain of native and not hatchery stock.

The rainbow trout is susceptible to enteric redmouth disease
Enteric redmouth disease
-Introduction:Enteric redmouth disease, or simply redmouth disease is a bacterial infection of freshwater and marine fish caused by the pathogen Yersinia ruckeri. It is primarily found in rainbow trout and other cultured salmonids. The disease is characterized by subcutaneous hemorrhaging of the...

. There has been considerable research conducted on redmouth disease, given its serious implications for rainbow trout farmers. The disease does not affect humans.

The U.S. National Marine Fisheries Service
National Marine Fisheries Service
The National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...

 has identified 15 populations, called Distinct Population Segments(DPSs), in Washington, Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

 and California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. Eleven of these DPSs are listed under the U.S. Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

 (ESA). One DPS on the Oregon Coast is designated a U.S. Species of Concern
Species of Concern
In wildlife conservation, Species of Concern is an informal term, not defined in the federal Endangered Species Act. The term commonly refers to species that are declining or appear to be in need of concentrated conservation actions. Many agencies and organizations maintain lists of these at-risk...

. Species of Concern are those species that lack sufficient data to determine whether to list the species under the ESA.

Rainbow trout, and subspecies thereof, are currently EPA approved indicator species for acute fresh water toxicity
Toxicity
Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...

 testing.

In 2010, the Oregon Department of Fish & Wildlife hatchery expects to more than double its take over 2009. The 2009 population grew 60% over 2008. Hatchery-taken fish will spawn tens of thousands of juvenile "smolts" that will be released to swim downstream and mature in the Pacific.

In March 2010, the Los Angeles Times
Los Angeles Times
The Los Angeles Times is a daily newspaper published in Los Angeles, California, since 1881. It was the second-largest metropolitan newspaper in circulation in the United States in 2008 and the fourth most widely distributed newspaper in the country....

reported that the New Zealand mud snail had infested watersheds in the Santa Monica Mountains, complicating efforts to improve stream-water quality for the steelhead. According to the article, the snails have expanded "from the first confirmed sample in Medea Creek in Agoura Hills to nearly 30 other stream sites in four years." Researchers at the Santa Monica Bay Restoration Commission believe that the snails' expansion may have been expedited after the mollusks traveled from stream to stream on the gear of contractors and volunteers.

Hatcheries have also been demonstrated to present a risk to wild steelhead populations. Releases of conventionally reared hatchery steelhead pose ecological risks to preexisting wild steelhead populations. Hatchery steelhead are typically larger than the wild form and can displace wild form juveniles from optimal habitat. Dominance of hatchery steelhead for optimal microhabitats within streams may reduce wild steelhead survival as a result of reduced foraging opportunity and increased rates of predation.

Fishing

Rainbow trout and steelhead are both highly desired food and sportfish. A number of angling methods are common. Rainbow trout are a popular target for fly fisher
Fly fishing
Fly fishing is an angling method in which an artificial 'fly' is used to catch fish. The fly is cast using a fly rod, reel, and specialized weighted line. Casting a nearly weightless fly or 'lure' requires casting techniques significantly different from other forms of casting...

s. Spinner
Spinner
Spinner may refer to:*Spinner Dolphin, a dolphin species*Spinnerbait, a type of fishing lure*Spinner , a graphical widget in a GUI*Spinner , a flying car from the film Blade Runner...

s, spoons, and small crankbaits can also be used productively, either casting or trolling. Rainbow trout can also be caught on live bait; nightcrawlers
Nightcrawlers
Nightcrawlers are a form of earthworm. Prized primarily for use as fishing bait, nightcrawlers are generally known as either Canadian or European...

, trout worms, and minnow
Minnow
Minnow is a general term used to refer to small freshwater and saltwater fish, especially those used as bait fish or for fishing bait. More specifically, it refers to small freshwater fish of the carp family.-True minnows:...

s are popular and effective choices.
The IGFA recognizes the world record for Rainbow Trout was caught on Saskatchewan
Saskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....

's Lake Diefenbaker
Lake Diefenbaker
Lake Diefenbaker is a reservoir in Southern Saskatchewan, Canada. It was formed by the construction of Gardiner Dam and the Qu'Appelle River Dam across the South Saskatchewan and Qu'Appelle Rivers respectively. Construction began in 1959 and the lake was filled in 1967. The lake is long with...

 by Sean Konrad on September 5 2009. The fish weighed 48 lb 0 oz (21.77 kg).

Hatcheries and farms

The first rainbow trout hatchery
Hatchery
A hatchery is a facility where eggs are hatched under artificial conditions, especially those of fish or poultry. It may be used for ex-situ conservation purposes, i.e. to breed rare or endangered species under controlled conditions; alternatively, it may be for economic reasons A hatchery is a...

 was established on San Leandro Creek
San Leandro Creek
San Leandro Creek is a year-round natural stream flowing along the east side of the range which comprises the Berkeley Hills and the San Leandro Hills, immediately east of Oakland. In the hills, it runs into Upper San Leandro Reservoir and then Lake Chabot, both manmade lakes lying north of the...

, a tributary of San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...

, in 1870 with trout production beginning in 1871. The hatchery was stocked with the locally native rainbow trout, and likely steelhead. The fish raised in this hatchery were shipped to hatcheries out of state for the first time in 1875, to Caledonia, New York
Caledonia, New York
Caledonia, New York may refer to:*Caledonia , New York, located in Livingston County*Caledonia , New York, located within the Town of Caledonia...

and then in 1876 to Northville, Michigan
Northville, Michigan
Northville is a city located in and divided by Oakland and Wayne counties in the U.S. state of Michigan and a suburb in Metro Detroit. The population was 5,970 at the 2010 census. The Oakland County portion is surrounded by the city of Novi. The Wayne County portion is surrounded by Northville...

. In 1877, another rainbow trout hatchery was established on Campbell Creek, a McCloud River
McCloud River
The McCloud River is a river that flows east of and parallel to the Sacramento River, long, in northern California in the United States. It drains a scenic mountainous area of the Cascade Range north of Redding...

 tributary. However, the McCloud River stock indiscriminately mixed rainbow trout with Redband trout
Redband trout
Redband trout is a fish name that may be a synonym for the rainbow trout, Oncorhynchus mykiss, but is also used more narrowly for inland subspecies with well-defined geographical distributions in the United States...

 (Oncorhynchus mykiss stonei).

They are farmed in many countries throughout the world. Since the 1950s commercial production has grown exponentially, particularly in Europe and recently in Chile. Worldwide, in 2007, 604695 tonnes (595,143 LT) of farmed salmon trout were harvested with a value of 2.589 billion US dollars. The largest producer is Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. In Chile and Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

, ocean cage production of steelhead has expanded to supply export markets. Inland production of rainbow trout to supply domestic markets has increased in countries such as Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

 and Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

. Other significant producing countries include the USA, Iran
Iran
Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 and the United Kingdom.

There are tribal commercial fisheries for steelhead in Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...

, the Washington
Washington State
Washington State may refer to:* Washington , often referred to as "Washington state" to differentiate it from Washington, D.C., the capital of the United States* Washington State University, a land-grant college in that state- See also :...

 Coast and in the Columbia River
Columbia River
The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...

.

Cultivated varieties

Golden rainbow trout are bred from a single mutated color variant of Oncorhynchus mykiss. Golden rainbow trout are predominantly yellowish, lacking the typical green field and black spots, but retaining the diffuse red stripe. The palomino trout is a mix of golden and common rainbow trout, resulting in an intermediate color. The golden rainbow trout should not be confused with the naturally occurring golden trout
Golden Trout
The golden trout is a sub-species of the rainbow trout, and it closley resembles the juvenile Rainbow trout. The fish is also known as the California golden trout and is native to Golden Trout Creek, Volcano Creek and the South Fork Kern River. Another variant, O. m...

.

As food

Rainbow trout is popular in Western cuisine and is caught wild
Fishing
Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....

 and farmed. It has tender flesh and a mild, somewhat nutty flavor. However, farmed trout and those taken from certain lakes have a pronounced earthy flavor which many people find unappealing; many shoppers therefore ascertain the source of the fish before buying. Wild rainbow trout that eat scuds (freshwater shrimp), insects such as flies, and crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

 are the most appealing. Dark red/orange meat indicates that it is either an anadromous steelhead or a farmed Rainbow trout given a supplemental diet with a high astaxanthin
Astaxanthin
Astaxanthin is a carotenoid. It belongs to a larger class of phytochemicals known as terpenes. It is classified as a xanthophyll, which means "yellow leaves". Like many carotenoids, it is a colorful, lipid-soluble pigment. Astaxanthin is found in microalgae, yeast, salmon, trout, krill, shrimp,...

 content. The resulting pink flesh is marketed under monikers like Ruby Red or Carolina Red.

Steelhead meat is pink like that of salmon, and is more flavorful than the light-colored meat of rainbow trout.

Medicine

The sperm of rainbow trout contains protamine
Protamine
Protamines are small, arginine-rich, nuclear proteins that replace histones late in the haploid phase of spermatogenesis and are believed essential for sperm head condensation and DNA stabilization. They may allow for denser packaging of DNA in spermatozoon than histones, but they must be...

, which counters the anticoagulant heparin
Heparin
Heparin , also known as unfractionated heparin, a highly sulfated glycosaminoglycan, is widely used as an injectable anticoagulant, and has the highest negative charge density of any known biological molecule...

. Protamine was originally isolated from fish sperm, but is now produced synthetically.

Subspecies

A few populations are recognized as subspecies:
  • Kamchatkan rainbow trout, Oncorhynchus mykiss mykiss (Walbaum
    Johann Julius Walbaum
    Johann Julius Walbaum was a physician, naturalist and taxonomist. He was the first to describe many previously unknown species from remote parts of the globe, such as the Great Barracuda , the Chum salmon from the Kamchatka River in Siberia, and the curimatá-pacú Johann Julius Walbaum (30 June...

    , 1792)
    .
  • Columbia River redband trout, Oncorhynchus mykiss gairdnerii (Richardson
    John Richardson (naturalist)
    Sir John Richardson was a Scottish naval surgeon, naturalist and arctic explorer.Richardson was born at Dumfries. He studied medicine at Edinburgh University, and became a surgeon in the navy in 1807. He traveled with John Franklin in search of the Northwest Passage on the Coppermine Expedition of...

    , 1836)
    .
  • Coastal rainbow trout/Steelhead trout, Oncorhynchus mykiss irideus (Gibbons, 1855).
  • Beardslee trout
    Beardslee trout
    Beardslee trout are a local form of Rainbow trout endemic to Lake Crescent in Washington. By some sources, they are treated as a subspecies....

    , isolated in Lake Crescent
    Lake Crescent
    Lake Crescent is a deep lake located entirely within Olympic National Park in Clallam County, Washington, United States, approximately west of Port Angeles, Washington on U.S. Route 101 and nearby to the small community of Piedmont...

     (Washington), Oncorhynchus mykiss irideus var. beardsleei (not a true subspecies, but a lake dwelling variety of Coastal rainbow trout) (Jordan, 1896).
  • Great Basin redband trout, Oncorhynchus mykiss newberrii (Girard, 1859).
  • Golden trout
    Golden Trout
    The golden trout is a sub-species of the rainbow trout, and it closley resembles the juvenile Rainbow trout. The fish is also known as the California golden trout and is native to Golden Trout Creek, Volcano Creek and the South Fork Kern River. Another variant, O. m...

    , Oncorhynchus mykiss aguabonita (Jordan
    David Starr Jordan
    David Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...

    , 1892)
    .
  • Kamloops rainbow trout, Oncorhynchus mykiss kamloops (Jordan, 1892).
  • Kern River rainbow trout, Oncorhynchus mykiss aguabonita var. gilberti (Jordan, 1894).
  • Sacramento golden trout, Oncorhynchus mykiss aguabonita var. stonei (Jordan, 1894).
  • Little Kern golden trout, Oncorhynchus mykiss aguabonita var. whitei (Evermann, 1906).
  • Baja California rainbow trout, Nelson's trout, or San Pedro Martir trout, Oncorhynchus mykiss nelsoni (Evermann, 1908).
  • Eagle Lake trout
    Eagle Lake trout
    Eagle Lake trout, Oncorhynchus mykiss aquilarum, is endemic to Eagle Lake, in Lassen County, California. It is a type of trout, known for its ability to withstand high alkalinity, that looks similar to rainbow trout.-Range:...

    , Oncorhynchus mykiss aquilarum (Snyder, 1917).
  • McCloud River redband, Oncorhynchus mykiss stonei
  • Sheepheaven Creek redband, Oncorhynchus mykiss spp.
  • Southern California Steelhead DPS
    Southern California Steelhead DPS
    The Southern California Steelhead DPS occurs from the Santa Maria River to the Tijuana River at the United States and Mexican Border in seasonally accessible rivers and streams. The Southern California Steelhead, much like its relatives further north, requires sufficient flows in their natal...

    , Oncorhynchus mykiss


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK