The cutthroat trout is a fish species of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Salmonidae native to cold-water

tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage b ...

of the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...

, and

Great Basin The Great Basin is the largest area of contiguous endorheic basin, endorheic watersheds, those with no outlets, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California ...

in North America. As a member of the genus ''

Oncorhynchus ''Oncorhynchus'' is a genus of fish in the family Salmonidae; it contains the Pacific salmon and Pacific trout. The name of the genus is derived from the Greek ὄγκος (ónkos, “lump, bend”) + ῥύγχος (rhúnkhos, “snout”), in r ...

'', it is one of the Pacific

trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salmoni ...

, a group that includes the widely distributed

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead (sometimes called "steelhead trout") is an anadromous (sea-run) form of the coasta ...

. Cutthroat trout are popular

gamefish Game fish, sport fish or quarry refer to popular fish pursued by recreational anglers, and can be freshwater or saltwater fish. Game fish can be eaten after being caught, or released after capture. Some game fish are also targeted commerciall ...

, especially among

angler Angler may refer to: * A fisherman who uses the fishing technique of angling * ''Angler'' (video game) * The angler, ''Lophius piscatorius'', a monkfish * More generally, any anglerfish in the order Lophiiformes * '' Angler: The Cheney Vice Presi ...

s who enjoy

fly fishing Fly fishing is an angling method that uses a light-weight lure—called an artificial fly—to catch fish. The fly is cast using a fly rod, reel, and specialized weighted line. The light weight requires casting techniques significantly diffe ...

. The common name "cutthroat" refers to the distinctive red coloration on the underside of the lower jaw. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''clarkii'' was given to honor explorer William Clark, coleader of the

Lewis and Clark Expedition The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select gro ...

. Cutthroat trout usually inhabit and

spawn Spawn or spawning may refer to: * Spawn (biology), the eggs and sperm of aquatic animals Arts, entertainment, and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** '' Spawn: Ar ...

in small to moderately large, clear, well- oxygenated, shallow rivers with gravel bottoms. They reproduce in clear, cold, moderately deep lakes. They are native to the

alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...

freestone stream In fly fishing, a freestone stream flows seasonally, based on the water supply. In the summer and fall, freestone streams grow warm and have reduced flow because water from snow melt is less readily available. In contrast to limestone streams, which ...

s that are typical tributaries of the rivers of the Pacific Basin, Great Basin and Rocky Mountains. Cutthroat trout spawn in the spring and may inadvertently but naturally

hybridize Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...

with rainbow trout, producing fertile

cutbow A cutbow ('' Oncorhynchus clarkii'' × ''mykiss'') is an interspecific fertile hybrid between a rainbow trout (''Oncorhynchus mykiss'') and a cutthroat trout (''O. clarkii''). Cutbow hybrids may occur naturally where the native ranges of both ...

s. Some

population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...

s of the coastal cutthroat trout are semi-anadromous. Several

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

of cutthroat trout are currently listed as

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensat ...

in their native ranges due to

habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and the

introduction Introduction, The Introduction, Intro, or The Intro may refer to: General use * Introduction (music), an opening section of a piece of music * Introduction (writing), a beginning section to a book, article or essay which states its purpose and g ...

of non-native species. Two subspecies, and , are considered

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

. Cutthroat trout are raised in hatcheries to restore populations in their native range, as well as stock non-native lake environments to support angling. The cutthroat trout type species and several subspecies are the official state fish of seven western U.S. states.

Taxonomy

The scientific name of the cutthroat trout is . Cutthroat trout were the first

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...

trout encountered by Europeans when in 1541, Spanish explorer

Francisco de Coronado Francisco is the Spanish and Portuguese form of the masculine given name ''Franciscus''. Nicknames In Spanish, people with the name Francisco are sometimes nicknamed "Paco". San Francisco de Asís was known as ''Pater Comunitatis'' (father of ...

recorded seeing trout in the

Pecos River The Pecos River ( es, Río Pecos) originates in north-central New Mexico and flows into Texas, emptying into the Rio Grande. Its headwaters are on the eastern slope of the Sangre de Cristo mountain range in Mora County north of Pecos, New Mexico ...

near

Santa Fe, New Mexico Santa Fe ( ; , Spanish for 'Holy Faith'; tew, Oghá P'o'oge, Tewa for 'white shell water place'; tiw, Hulp'ó'ona, label=Tiwa language, Northern Tiwa; nv, Yootó, Navajo for 'bead + water place') is the capital of the U.S. state of New Mexico. ...

. These were most likely Rio Grande cutthroat trout . The species was first described in the journals of explorer William Clark from specimens obtained during the

from the Missouri River near

Great Falls, Montana Great Falls is the third most populous city in the U.S. state of Montana and the county seat of Cascade County. The population was 60,442 according to the 2020 census. The city covers an area of and is the principal city of the Great Falls, M ...

, and these were most likely the westslope cutthroat trout . As one of Lewis and Clark's many missions was to describe the flora and fauna encountered during their expedition, cutthroat trout were given the name in honor of William Clark. In 1836, the

type specimen In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...

of was described by naturalist John Richardson from a tributary of the lower

Columbia River The Columbia River (Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, C ...

, identified as the "Katpootl", which was perhaps the Lewis River, as there was a Multnomah village of similar name at the

confluence In geography, a confluence (also: ''conflux'') occurs where two or more flowing bodies of water join to form a single channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main stem); o ...

. This type specimen was most likely the coastal cutthroat trout subspecies . Until the 1960s, populations of westslope cutthroat trout and

Yellowstone cutthroat trout The Yellowstone cutthroat trout (''Oncorhynchus clarkii bouvieri'') is a subspecies of the cutthroat trout (''Oncorhynchus clarkii''). It is a freshwater fish in the salmon family (family Salmonidae). Native only to a few U.S. states, their ...

were lumped into one subspecies; ''Salmo clarkii lewisii''. Biologists later split the group into two subspecies, christening the name westslope cutthroat trout with the ''lewisii'' name which honors explorer

Meriwether Lewis Meriwether Lewis (August 18, 1774 – October 11, 1809) was an American explorer, soldier, politician, and public administrator, best known for his role as the leader of the Lewis and Clark Expedition, also known as the Corps of Discovery, with ...

and renaming the Yellowstone cutthroat trout ''Salmo bouvierii'', the first name given to the Yellowstone cutthroat trout by

David Starr Jordan David Starr Jordan (January 19, 1851 – September 19, 1931) was the founding president of Stanford University, serving from 1891 to 1913. He was an ichthyologist during his research career. Prior to serving as president of Stanford Univer ...

in 1883 honoring a U.S. Army Captain Bouvier. In 1989, morphological and genetic studies indicated trout of the Pacific Basin were genetically closer to Pacific salmon (''Oncorhynchus'' species) than to the '' Salmo''s–

brown trout The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morph ...

Atlantic salmon The Atlantic salmon (''Salmo salar'') is a species of ray-finned fish in the family Salmonidae. It is the third largest of the Salmonidae, behind Siberian taimen and Pacific Chinook salmon, growing up to a meter in length. Atlantic salmon are ...

of the

Atlantic Basin The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe and ...

. Thus, in 1989, taxonomic authorities moved the rainbow, cutthroat and other Pacific Basin trout into the genus ''Oncorhynchus''.

Subspecies

Behnke in his salmon and trout handbook of 2002 recognized 14

of cutthroat trout that are each native to a separate geographic area. Not all of them were scientifically described, and different views on the taxonomic identities have been presented in some cases. It has been suggested that the cutthroat trout evolved from a common ''Oncorhynchus'' ancestor that migrated along the Pacific Coast and into the mountain west primarily via the Columbia and

Snake River The Snake River is a major river of the greater Pacific Northwest region in the United States. At long, it is the largest tributary of the Columbia River, in turn, the largest North American river that empties into the Pacific Ocean. The Snake ...

basins 3-5 million years ago, in the late

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

epochs. These epochs had repeated glacial and

interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene in ...

periods that would have caused repeated fracturing and isolation of cutthroat trout populations, eventually resulting in the different subspecies found today. The 14 subspecies are found in four evolutionary groups—Coastal, Westslope, Yellowstone and Lahontan.

Description

Throughout their native and introduced ranges, cutthroat trout vary widely in size, coloration and habitat selection. Their coloration can range from golden to gray to green on the back. Cutthroat trout can generally be distinguished from rainbow trout by the presence of basibranchial teeth at the base of tongue and a

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

ry that extends beyond the posterior edge of the eye. Depending on subspecies, strain and habitat, most have distinctive red, pink, or orange linear marks along the underside of their

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

s in the lower folds of the

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

plates. These markings are responsible for the common name "cutthroat", first given to the trout by outdoor writer Charles Hallock in an 1884 article in ''The American Angler''. These markings are not unique to the species. Some coastal rainbow trout and

Columbia River redband trout The Columbia River redband trout, the inland redband trout or the interior redband troutlacustrine populations have attained weights ranging from in ideal conditions. The largest cutthroat trout subspecies is the Lahontan cutthroat trout . These fish average in small streams and in larger rivers and lakes. In ideal environments, the Lahontan cutthroat trout attains typical weights of . The world record cutthroat trout is a Lahontan at and .

Lifecycle

Cutthroat trout usually inhabit and spawn in small to moderately large, clear, well-oxygenated, shallow rivers with

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

bottoms. They are native to the alluvial or

s typical of tributaries of the Pacific Basin, Great Basin and Rocky Mountains. They spawn in the spring, as early as February in coastal rivers and as late as July in high mountain lakes and streams. Spawning begins when water temperatures reach . Cutthroat trout construct a redd in the stream gravel to lay eggs. The female selects the site for and excavates the redd. Females, depending on size, lay between 200 and 4,400 eggs. Eggs are fertilized with milt (sperm) by an attending male. Eggs hatch into alevins or sac fry in about a month and spend two weeks in the gravel while they absorb their yolk sack before emerging. After emergence, fry begin feeding on

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

. Juvenile cutthroat trout typically mature in three to five years. Lake-resident cutthroat trout are usually found in moderately deep, cool lakes with adequate shallows and vegetation for good food production. Lake populations generally require access to gravel-bottomed streams to be self-sustaining, but occasionally spawn on shallow gravel beds with good water circulation. Cutthroat trout naturally interbreed with the closely related rainbow trout, producing fertile

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two dif ...

s commonly called "

s". This hybrid generally bears similar coloration and overall appearance to the cutthroat trout, usually retaining the characteristic orange-red slash. Cutbow hybrids often pose a taxonomic difficulty when trying to distinguish any given specimen as a rainbow or cutthroat trout. In addition, cutthroat trout may hybridize with , the

Gila trout The Gila trout (''Oncorhynchus gilae'') is a species of salmonid, related to the rainbow, native to the Southwest United States. Prior to 2006 the Gila trout was federally listed as endangered. In July 2006, after much work by the Game and Fish ...

and , the

Apache trout The Apache trout, ''Oncorhynchus apache'', is a species of freshwater fish in the salmon family (family Salmonidae) of order Salmoniformes. It is one of the Pacific trouts. Description The Apache trout measures in length from , and weighs bet ...

in regions where their ranges overlap.

Ecology

Range

Cutthroat trout are native to western North America and have evolved through

geographic isolation Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

into 14 subspecies, each native to a different major

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, t ...

. Native cutthroat trout species are found along the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...

coast from

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

through British Columbia into northern

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

, in the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...

, the

and throughout the Rocky Mountains including southern

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

. Some coastal populations of the coastal cutthroat trout are semianadromous, spending a few months in marine environments to feed as adults and returning to fresh water from fall through early spring to feed on insects and spawn. Cutthroat trout have the second-largest historic native range of North American trout; the lake trout having the largest. Ranges of some subspecies, particularly the westslope cutthroat trout , have been reduced to less than 10 percent of their historic range due to habitat loss and introduction of non-native species. Although members of ''Oncorhynchus'', the Pacific trout/salmon species, three subspecies—the westslope , the greenback and Yellowstone cutthroat trout —evolved populations east of the

Continental Divide A continental divide is a drainage divide on a continent such that the drainage basin on one side of the divide feeds into one ocean or sea, and the basin on the other side either feeds into a different ocean or sea, or else is endorheic, not ...

in the upper Missouri River basin, upper

Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the Osage ...

and Platte River basins and upper Yellowstone River basin, each which drain into the Atlantic basin via the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...

(in 2005, researchers published a report stating that a natural distribution of , the Conchos trout, is also located in an Atlantic basin drainage). Scientists believe that the climatic and geologic conditions 3-5 million years ago allowed cutthroat trout from the

to migrate over the divide into the Yellowstone plateau via

Two Ocean Pass Two Ocean Pass is a mountain pass on North America's Continental Divide, in the Teton Wilderness, which is part of Wyoming's Bridger-Teton National Forest. The pass is notable for Parting of the Waters, where one stream, North Two Ocean Creek, ...

. There is also evidence that

Yellowstone Lake Yellowstone Lake is the largest body of water in Yellowstone National Park. The lake is above sea level and covers with of shoreline. While the average depth of the lake is , its greatest depth is at least . Yellowstone Lake is the largest fre ...

once drained south into the Snake River drainage. Evidence suggests that the westslope cutthroat trout was able to establish populations east of the divide via Summit Lake at Marias Pass which at one time connected the Flathead River drainage with the upper Missouri River drainage. Scientists speculate that there are several mountain passes associated with the headwaters of the

Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid drainage basin, watershed that encompasses parts of ...

drainage and Arkansas/Platte River drainages that would have allowed migration of cutthroat trout east of the divide. Cutthroat trout have been introduced into non-native waters outside their historic native range, but not to the extent of the rainbow trout . Within the native range of the Yellowstone cutthroat trout, U.S. Fisheries Bureau and

National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational propertie ...

authorities introduced Yellowstone cutthroat trout into many fishless lakes in

Yellowstone National Park Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress with the Yellowston ...

. Cutthroat trout were introduced into

Lake Michigan Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume () and the third-largest by surface area (), after Lake Superior and Lake Huron. To the east, its basin is conjoined with that o ...

tributaries in the 1890s and sporadically in the early 20th century, but never established wild populations. A population of Yellowstone cutthroat trout purportedly has been established in

Lake Huron Lake Huron ( ) is one of the five Great Lakes of North America. Hydrology, Hydrologically, it comprises the easterly portion of Lake Michigan–Huron, having the same surface elevation as Lake Michigan, to which it is connected by the , Strait ...

. Although cutthroat trout are not native to

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

, they are routinely introduced by the Arizona Game and Fish Department into high mountain lakes in the White Mountains in the northeastern region of that state.

Habitat

Cutthroat trout require cold, clear, well-oxygenated, shallow rivers with gravel bottoms or cold, moderately deep lakes. Healthy stream-side vegetation that reduces siltation is typical of healthy cutthroat trout habitat and

beaver Beavers are large, semiaquatic rodents in the genus ''Castor'' native to the temperate Northern Hemisphere. There are two extant species: the North American beaver (''Castor canadensis'') and the Eurasian beaver (''C. fiber''). Beavers ar ...

ponds may provide refuge during periods of drought and over winter. Most populations stay in fresh water throughout their lives and are known as nonmigratory, stream-resident or

riverine A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

populations. The coastal cutthroat trout is the only cutthroat trout subspecies to

coevolve In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. The term sometimes is used for two traits in the same species affecting each other's evolution, as well ...

through its entire range with the coastal rainbow trout (''O. m. irideus''). Portions of the westslope cutthroat trout's range overlap with the Columbia River redband trout , but the majority of its native range is in headwater tributary streams above major waterfalls and other barriers to upstream migration. At least three subspecies are confined to isolated basins in the Great Basin and can tolerate

saline Saline may refer to: * Saline (medicine), a liquid with salt content to match the human body * Saline water, non-medicinal salt water * Saline, a historical term (especially US) for a salt works or saltern Places * Saline, Calvados, a commune in ...

alkaline In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a base (chemistry), basic, ionic compound, ionic salt (chemistry), salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as ...

water. Cutthroat trout are

opportunistic feeders Feeding is the process by which organisms, typically animals, obtain food. Terminology often uses either the suffixes -vore, -vory, or -vorous from Latin ''vorare'', meaning "to devour", or -phage, -phagy, or -phagous from Greek φαγ ...

. Stream-resident cutthroat trout primarily feed on

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

l and adult forms of aquatic insects (typically caddisflies,

stoneflies Plecoptera is an order of insects, commonly known as stoneflies. Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to be one of the mo ...

mayflies Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the orde ...

and aquatic

diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

ns), and adult forms of terrestrial insects (typically ants,

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...

s and

cricket Cricket is a bat-and-ball game played between two teams of eleven players on a field at the centre of which is a pitch with a wicket at each end, each comprising two bails balanced on three stumps. The batting side scores runs by striki ...

s) that fall into the water, fish eggs, small fish, along with crayfish, shrimp and other crustaceans. As they grow the proportion of fish consumed increases in most populations. In saltwater estuaries and along beaches, Coastal cutthroat trout feed on small fish such as

sculpin A sculpin is a type of fish that belongs to the superfamily Cottoidea in the order Scorpaeniformes.Kane, E. A. and T. E. Higham. (2012)Life in the flow lane: differences in pectoral fin morphology suggest transitions in station-holding demand a ...

sand lance A sand lance or sandlance is a fish belonging to the family Ammodytidae. Several species of sand lances are commonly known as "sand eels", though they are not related to true eels. Another variant name is launce, and all names of the fish are ...

, salmon fry and

herring Herring are forage fish, mostly belonging to the family of Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, i ...

. They also consume

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

, small

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...

and krill. In fresh water, they consume the same diet as stream resident trout—aquatic insects and crustaceans, amphibians, earthworms, small fish and fish eggs. Within the range of the bull trout the cutthroat trout is a

forage fish Forage fish, also called prey fish or bait fish, are small pelagic fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food ...

for the

piscivorous A piscivore () is a carnivorous animal that eats primarily fish. The name ''piscivore'' is derived . Piscivore is equivalent to the Greek-derived word ichthyophage, both of which mean "fish eater". Fish were the diet of early tetrapod evoluti ...

bull trout.

Artificial propagation

Various subspecies of cutthroat trout are raised in commercial, state and federal hatcheries for introduction into suitable native and non-native riverine and lacustrine environments. In the early 20th century, several hatcheries were established in Yellowstone National Park by the

U.S. Bureau of Fisheries The United States Fish Commission, formally known as the United States Commission of Fish and Fisheries, was an agency of the United States government created in 1871 to investigate, promote, and preserve the fisheries of the United States. In 1 ...

. These hatcheries not only produced stocks of the Yellowstone cutthroat trout for the park, but also took advantage of the great spawning stock of cutthroat trout to supply eggs to hatcheries around the U.S. Between the years 1901 and 1953 a total of 818 million trout eggs were exported from the park to hatcheries throughout the U.S. The Lahontan National Fish Hatchery operated by the U.S. Fish and Wildlife Service exists to restore populations of the Lahontan cutthroat trout in

Pyramid A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilat ...

, Walker, Fallen Leaf,

June June is the sixth month of the year in the Julian and Gregorian calendars and is the second of four months to have a length of 30 days, and the third of five months to have a length of less than 31 days. June contains the summer solstice in ...

, Marlette, and Gull Lakes and the

Truckee River The Truckee River is a river in the U.S. states of California and Nevada. The river flows northeasterly and is long.U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed October 20, 2012 The ...

in California and Nevada. The hatchery produces about 300,000–400,000 Lahontan cutthroat trout fry annually. The

Jackson National Fish Hatchery Jackson National Fish Hatchery is a National fish hatchery in Jackson, Wyoming. The hatchery is run by the U.S. Fish and Wildlife Service. The hatchery is physically located on the National Elk Refuge, a protected feeding ground for elk that win ...

produces around 400,000 Snake River fine-spotted cutthroat trout annually to support fisheries in Idaho and Wyoming. The

Leadville National Fish Hatchery Leadville National Fish Hatchery established in 1889 west of Leadville, Colorado is one of 70 hatcheries in the National Fish Hatchery System. It is managed by the United States Fish and Wildlife Service. It lies within the Mount Massive Wildern ...

produces 125,000–200,000 Snake River fine-spotted, greenback cutthroat and rainbow trout annually to support fishing in the Fryingpan and Arkansas River drainages and other Colorado waters. The Bozeman Fish Technology Center, formerly a cutthroat trout fish hatchery in

Bozeman, Montana Bozeman is a city and the county seat of Gallatin County, Montana, United States. Located in southwest Montana, the 2020 census put Bozeman's population at 53,293, making it the fourth-largest city in Montana. It is the principal city of th ...

, plays a major role in the restoration of the greenback and westslope cutthroat trout subspecies.

Population threats

The historic native range of cutthroat trout has been reduced by

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in th ...

, urbanization and habitat loss due to mining, livestock grazing and logging. Population densities have been reduced and in some cases populations have disappeared though competition with non-native

brook A brook is a small river or natural stream of fresh water. It may also refer to: Computing *Brook, a programming language for GPU programming based on C *Brook+, an explicit data-parallel C compiler *BrookGPU, a framework for GPGPU programming ...

, brown, lake and rainbow trout,

kokanee salmon The kokanee salmon (''Oncorhynchus nerka''), also known as the kokanee trout, little redfish, silver trout, kikanning, Kennerly's salmon, Kennerly's trout, or Walla, is the non-anadromous form of the sockeye salmon (meaning that they do not migrat ...

, lake whitefish and

mysis shrimp Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in ...

which were introduced in the late 19th and early 20th centuries. Scientists believe the westslope cutthroat trout will eventually be extirpated from the large lakes in Western Montana due to the trophic cascades resulting from lake trout and mysis shrimp introductions. The most serious current threats to several subspecies are interspecific breeding with introduced rainbow trout, creating hybrid cutbows, and intraspecific breeding with other introduced cutthroat trout subspecies. In the

Greater Yellowstone Ecosystem The Greater Yellowstone Ecosystem (GYE) is one of the last remaining large, nearly intact ecosystems in the northern temperate zone of the Earth. It is located within the northern Rocky Mountains, in areas of northwestern Wyoming, southwestern Mo ...

, the presence of lake trout in

in Yellowstone National Park has caused a serious decline in Yellowstone cutthroat trout . Outbreaks of

whirling disease ''Myxobolus cerebralis'' is a myxosporean parasite of salmonids (salmon and trout species) that causes whirling disease in farmed salmon and trout and also in wild fish populations. It was first described in rainbow trout in Germany in 1893, b ...

in major spawning tributaries within the native ranges have also caused declines. Most subspecies of cutthroat trout are highly susceptible to whirling disease, although the Snake River fine-spotted cutthroat trout appears to be resistant to the parasite.

Interspecific and intraspecific breeding

The most serious impact on the genetic purity of most cutthroat trout subspecies results from interspecific and intraspecific breeding resulting in hybrids that carry the

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

s of both parents. In inland populations, the introduction of rainbow trout from hatchery stocks have resulted in cutbow hybrids that continue to diminish the genetic purity of many cutthroat trout subspecies. The introduction of hatchery-raised Yellowstone cutthroat trout into native ranges of other cutthroat trout subspecies, particularly the westslope cutthroat trout, has resulted in intraspecific breeding and diminished genetic purity of the westslope subspecies. As such, populations of genetically pure westslope cutthroat trout are very rare and localized in streams above barriers to upstream migrations by introduced species. Fisheries biologist

Robert J. Behnke Dr. Robert J. Behnke (December 30, 1929 – September 13, 2013) was an American fisheries biologist and conservationist who was recognized as a world authority on the classification of salmonid fishes. He was popularly known as "Dr. Trout" or "T ...

attributes the extinction of the yellowfin cutthroat trout and Alvord cutthroat trout subspecies to the introduction of non-native rainbow trout.

Decline of the Yellowstone subspecies

The population at the core of the Yellowstone cutthroat trout's native range, in Yellowstone Lake, declined significantly in the 1960s due to

overharvest Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term app ...

of mature cutthroat trout by anglers, as well as overharvesting of eggs by hatcheries in the early 20th century. Managers implemented

catch and release Catch and release is a practice within recreational fishing where after capture, often a fast measurement and weighing of the fish is performed, followed by posed photography as proof of the catch, and then the fish are unhooked and returned ...

, which required anglers to return their catches to the lake, and they terminated hatchery operations in the park, which allowed the cutthroat trout to recover. Then, in 1994, park officials discovered lake trout in Yellowstone Lake. Although lake trout were established in

Shoshone The Shoshone or Shoshoni ( or ) are a Native American tribe with four large cultural/linguistic divisions: * Eastern Shoshone: Wyoming * Northern Shoshone: southern Idaho * Western Shoshone: Nevada, northern Utah * Goshute: western Utah, easter ...

, Lewis and

Heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...

Lakes in the Snake River drainage from U.S. government stocking operations in 1890, they were never officially introduced into the Yellowstone River drainage and their presence there is probably the result of accidental or illegal introductions. By 2000, the cutthroat trout population had declined to less than 10 percent of its early 20th century abundance. However, aggressive lake trout eradication programs have killed over 1 million lake trout since 1996, and the hope is that this will lead to a restoration of cutthroat numbers. Cutthroat trout co-exist with lake trout in Heart Lake, an isolated back-country lake at the head of the Heart River that gets little angling pressure.

Angling

Cutthroat trout are prized as a gamefish, particularly by fly anglers. They are regulated as a gamefish in every state and province they occur in. From the Yellowstone cutthroat trout fishery in Yellowstone National Park, the unique Lahontan cutthroat trout fishery in Pyramid Lake in Nevada, and the small stream fisheries of the westslope cutthroat trout to saltwater angling for sea-run cutthroat trout on the Pacific coast, cutthroat trout are a popular quarry for trout anglers throughout their ranges. The all-tackle world record is caught in Pyramid Lake in December 1925. Their propensity to feed on aquatic and terrestrial insects make them an ideal quarry for the fly angler.

Sea-run fishing along the Pacific Coast

From Alaska to Northern California, coastal cutthroat trout in sea-run, resident stream and lacustrine forms are sought by anglers.

Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected ma ...

in Washington is a stronghold of sea-run cutthroat trout fishing with its many tributaries and protected saltwater inlets and beaches. Fly anglers search for sea-run cutthroat trout along beaches, river mouths and estuaries year round. In the lower reaches of larger rivers, anglers in drift boats float the rivers searching for trout along the wooded shorelines. In addition to a cutthroat trout sport fishery managed by the Alaska Department of Fish and Game, the Federal Subsistence Management Program manages coastal cutthroat trout subsistence fisheries in Southeast Alaska.

Yellowstone fishery

was established in 1872. By the 1890s, the Yellowstone cutthroat trout fishery in the

Yellowstone River The Yellowstone River is a tributary of the Missouri River, approximately long, in the Western United States. Considered the principal tributary of upper Missouri, via its own tributaries it drains an area with headwaters across the mountains an ...

and Yellowstone Lake were well known and being promoted in national guidebooks. In 1902, anticipating the completion of the east entrance road from Cody, Wyoming, Captain

Hiram M. Chittenden Hiram Martin Chittenden (October 25, 1858 – October 9, 1917) was an American engineer and historian. A graduate of West Point, he was the Seattle district engineer for the Army Corps of Engineers from 1906 to 1908). Chittenden was one of ...

supervised the construction of the first "Fishing Bridge" across the outlet of Yellowstone Lake. Fishing Bridge was rebuilt in 1919, and reconstructed in 1937, primarily to accommodate vehicle traffic. Between 1916 and 1931, a large development of campgrounds, cabins, stores and service facilities were built just east of the bridge to support anglers. This area is now known as the Fishing Bridge Historic District. The 1937 bridge boasted pedestrian walkways on either side of the roadway to give more room to anglers. Angling in the river, at Fishing Bridge and in the lake, boomed during the 1950s and 1960s and over harvest caused a significant decline in the fishery. Consequently, in 1973, fishing was no longer permitted from Fishing Bridge.

Pyramid Lake Lahontan subspecies fishery

The Pyramid Lake strain of the Lahontan cutthroat trout, source of the world record and native to Pyramid Lake,

Lake Tahoe Lake Tahoe (; was, Dáʔaw, meaning "the lake") is a Fresh water, freshwater lake in the Sierra Nevada (U.S.), Sierra Nevada of the United States. Lying at , it straddles the state line between California and Nevada, west of Carson City, Nevad ...

and the Truckee River, was brought to near-extinction in the two decades between the 1920s-40s from overharvest, introduced species and loss of spawning habitat. In the 1970s, Pyramid Lake was stocked with Lahontan cutthroat trout strains still surviving in some nearby lakes, but they were not the large Pyramid Lake strain. Although the Pyramid Lake Paiute Tribe had been successful in re-establishing a cutthroat trout fishery on the reservation in Pyramid Lake, the cutthroat trout were not the large fish of the late 19th and early 20th century. In the late 1970, biologists discovered a surviving population of a pure Pyramid Lake strain in a small headwaters stream on the Nevada-Utah border that had at some point around 1900 been introduced into the stream. In 1995, the U.S. Fish and Wildlife Service began rearing these fish in the Lahontan National Fish Hatcheryin

Gardnerville, Nevada Gardnerville is an unincorporated town in Douglas County, Nevada, adjacent to the county seat of Minden. The population was 6,211 at the time of th2020 Census U.S. Route 395 runs through the center of Gardnerville. State Route 207, known as Ki ...

. In 2006, the Pyramid Lake strain of Lahontan cutthroat trout were reintroduced into the lake. As Pyramid Lake has a very shallow shoreline, anglers use ladders to stand comfortably in of water and cast to trout cruising along shoreline breaks. Considered a "world-class" fishery, anglers routinely catch cutthroat trout exceeding .

As a symbol

The cutthroat trout is the

state fish This is a list of official and unofficial U.S. state fishes: __TOC__ Table See also * Lists of U.S. state insignia * Lists of U.S. state animals Notes References Netstate.com state fish tables External links {{state insignia .State ...

of Idaho, Montana and Wyoming, while particular subspecies of cutthroat are the state fish of Colorado, Nevada, New Mexico and Utah. * Idaho Montana and Wyoming–Cutthroat trout * Colorado–Greenback cutthroat trout * Nevada–Lahontan cutthroat trout * New Mexico–Rio Grande cutthroat trout * Utah–Bonneville cutthroat trout

References

External links

* *
Dr. Dave Neely podcast (includes discussion of cutthroat trout diversity)
{{Taxonbar, from=Q2717060 Oncorhynchus Cold water fish Fish of the Pacific Ocean Fish of Canada Fish of the Western United States Freshwater fish of North America Freshwater fish of the United States Fauna of the Northwestern United States Fauna of the Southwestern United States Fauna of California Fauna of the Rocky Mountains Fauna of the Sierra Nevada (United States) Fish described in 1836 Symbols of Wyoming