Westslope cutthroat trout | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Salmoniformes |
Family: | Salmonidae |
Genus: | Oncorhynchus |
Species: | |
Subspecies: | O. l. lewisi |
Trinomial name | |
Oncorhynchus lewisi lewisi (G. Suckley, 1856) | |
The historic distribution of westslope cutthroat trout in the United States (modified from Behnke 1992). The large region consists primarily of the upper Columbia River and upper Missouri River basins; some waters in the eastern part of this region may not have been occupied historically (MTFWP, in litt. 1998). Also shown are the Lake Chelan and Methow River drainages in Washington and the John Day River drainage in Oregon. [2] | |
Synonyms [3] | |
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The westslope cutthroat trout (Oncorhynchus lewisi), also known as the black-spotted trout, common cutthroat trout and red-throated trout is a species of the cutthroat trout group and is a freshwater fish in the salmon family (family Salmonidae) of order Salmoniformes. [4] The cutthroat is the Montana state fish. [5] This subspecies is a species of concern in its Montana [6] and British Columbia [7] ranges and is considered threatened in its native range in Alberta. [8]
The scientific name of the Westslope cutthroat trout is Oncorhynchus lewisi, [9] [10] as it was first described in the journals of explorer William Clark from specimens obtained during the Lewis and Clark Expedition from the Missouri River near Great Falls, Montana. Cutthroat trout were given the name Salmo clarki in honor of William Clark, who co-led the expedition of 1804–1806. [11] One of Lewis and Clark's missions was to describe the flora and fauna encountered during the expedition. The type specimen of S. clarki was described by naturalist John Richardson in 1836 from a tributary of the lower Columbia River, identified as the "Katpootl", [11] which was perhaps the Lewis River as there was a Multnomah village of similar name at the confluence. This type specimen was most likely the coastal cutthroat subspecies. [12] In 1853, naturalist George Suckley while working for the Pacific Railroad Survey led by Isaac Stevens collected specimens of westslope cutthroat trout by fly fishing below the Great Falls on the Missouri River. In 1856, he described the trout as Salar lewisi to honor explorer Meriwether Lewis. [13] In David Starr Jordan and Barton Warren Evermann's A Check-list of the Fishes and Fishlike Vertebrates of North and Middle America (1896), the name Salmo mykiss lewisi was given to Yellowstone trout or cut-throat trout and included a reference to specimens collected from the Missouri River by George Suckley. [14] In 1898, Jordan and Evermann changed the name of cutthroat trout to Salmo clarki. [15] Salmo clarki lewisi persisted as the subspecies name for both the Yellowstone cutthroat and westslope cutthroat trout until 1971 when fisheries biologist Robert J. Behnke gave the name Salmo clarki bouvieri to the Yellowstone cutthroat with Salmo clarki lewisi reserved for the westslope cutthroat trout. [12]
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 (S. trutta) or Atlantic salmon (S. salar) of the Atlantic basin. [16] Thus, in 1989, taxonomic authorities moved the rainbow, cutthroat and other Pacific basin trout into the genus Oncorhynchus. [17]
This single species (O. clarkii) classification is now changed. [9] [10] [18] Genetic, taxonomic, and geologic studies [19] [20] have determined that cutthroat trout should be divided into four distinct species, with each having multiple subspecies corresponding to the evolutionary lineages [21] found within major river basins, except for the Coastal cutthroat trout. [22]
Common name | Scientific name* | Range | Image |
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Missouri River cutthroat trout | O. lewisi lewisi | Native to the Missouri River drainage from the Judith River upstream to the headwaters. Captain Meriwether Lewis of the Lewis and Clark Expedition described trout caught near the Great Falls of the Missouri River in Montana on June 13th, 1805. [23] [24] | |
Neoboreal cutthroat trout | O. lewisi ssp. | Largest native range of all Westslope Cutthroat, and are native to parts of the upper Columbia, Fraser and Saskatchewan watersheds in Washington, Idaho, Montana, British Columbia, and Alberta. Several disjunct populations in British Columbia that were initially classified as a distinct subspecies the Alpine Cutthroat, [25] but based on taxonomic characteristics and genetics these populations clearly align with the Neoboreal Cutthroat. [26] [24] | |
Coeur d’ Alene cutthroat trout | O. lewisi ssp. | Native to the Coeur d’ Alene River drainage in Northern Idaho. [23] [24] | |
St. Joe cutthroat trout | O. lewisi ssp. | Native the St. Joe watershed of the Idaho panhandle. Neoboreal subspecies inhabit the lower reaches of the Coeur d’Alene and St. Joe watersheds. It remains uncertain what factors distinguish them from the St. Joe Westslope Cutthroat or whether these Neoboreal fish are native to these watersheds. [23] [24] | |
North Fork Clearwater cutthroat trout | O. lewisi ssp. | Native to the North Fork Clearwater River and its tributaries including Kelly Creek in Idaho. [23] [24] | |
Clearwater Headwater cutthroat trout | O. lewisi ssp. | Restricted to the upper Selway River upstream of Selway Falls and the South Fork Clearwater approximately upstream of the Crooked River. The exact boundary is currently not known. [23] [24] | |
Clearwater-Eastern Cascades cutthroat trout | O. lewisi ssp. | Native to the mainstem Clearwater River, Locsha, and lower Selway Rivers in Idaho, as well as the Eastern Cascade Mountains from the Methow River to the Yakima River in Washington State. [23] [24] [27] | |
Salmon River cutthroat trout | O. lewisi ssp. | Native to the Salmon River watershed in central Idaho. [23] [24] [28] | |
John Day cutthroat trout | O. lewisi ssp. | Native to about 220 miles (355 km) of 41 tributaries to the John Day River watershed in Oregon. Has the smallest and southern-most range of all Westslope Cutthroat. [23] [24] [29] |
The fish has teeth under its tongue, on the roof of the mouth, and in the front of the mouth. Westslope cutthroat are common in both headwaters lake and stream environments. They feed mainly on insects and zooplankton. The average length of the fish is about 8-12 inches (30 cm) and rarely exceeds 18 inches (46 cm). The skin has small dark freckle-like spots clustered towards the tail, and is mostly orange-hued. They can be distinguished from rainbow trout by the red, pink, or orange marking beneath the jaw (hence the name "cutthroat").
Westslope cutthroat trout are native in northern Idaho's and British Columbia's upper Columbia River system and northern tributaries of the Snake River, but not the Snake River's main stem to the south. East of the Continental Divide in Alberta and Montana, Westslope cutthroat trout are native to the upper Missouri, Milk and North Saskatchewan rivers, but not the Yellowstone River to the south. In Montana, the historic range extended east to the mouth of the Judith River and south into the Madison, Gallatin and Jefferson river systems. [13] Isolated populations of Westslope cutthroat trout exist in upper tributaries of the John Day River in the Strawberry Mountains of Oregon [30] and Columbia River tributaries along the eastern side of the Cascade Range in Washington. Isolated populations exist in the Fraser River basin in British Columbia. [13] Existing populations of genetically pure Westslope cutthroat trout exist in less than three percent of its historic range.
Westslope cutthroat trout reflect three life strategies—adfluvial, fluvial, or stream resident. Adfluvial fish live in the large lakes in the upper Columbia River drainage and spawn in lake tributaries. Fluvial fish live in medium to large rivers but migrate to tributaries for spawning. Most adults return to the river or lake after spawning. Stream resident fish complete their entire life in tributaries. All three forms occur in most basins. [31]
Genetically pure Westslope cutthroat trout have been extirpated throughout most of their historic range due to habitat loss and introduction of non-native species. Remaining populations survive in isolated populations, mostly in headwater streams above natural downstream barriers. The introduction of rainbow and brown trout into Missouri River tributaries eliminated the Westslope cutthroat trout from most of its eastern range in Montana. Introductions of non-native kokanee salmon (Oncorhynchus nerka), lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) into Flathead Lake and the Flathead River system caused drastic declines in Westslope cutthroat trout populations. [13] Existing populations are in imminent danger from land-use activities and hybridization with introduced rainbow trout (resulting in cutbows) [32] and Yellowstone cutthroat trout. Even the strongest populations in Glacier National Park and the Flathead Basin of Montana are in serious decline. Reasons for the critical condition of the subspecies include habitat destruction from logging, road building, grazing, mining, urban development, agriculture and dams, introduction of non-native hatchery strains, competition and hybridization from introduced non-native fish species. [33]
Trout is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera Oncorhynchus, Salmo and Salvelinus, all of which are members of the subfamily Salmoninae in the family Salmonidae. The word trout is also used for some similar-shaped but non-salmonid fish, such as the spotted seatrout/speckled trout.
The rainbow trout is a species of trout native to cold-water tributaries of the Pacific Ocean in North America and Asia. The steelhead is an anadromous (sea-run) form of the coastal rainbow trout(O. m. irideus) or Columbia River redband trout (O. m. gairdneri) that usually returns to freshwater to spawn after living two to three years in the ocean. Freshwater forms that have been introduced into the Great Lakes and migrate into tributaries to spawn are also called steelhead.
The cutthroat trout is a group of four fish species of the family Salmonidae native to cold-water tributaries of the Pacific Ocean, Rocky Mountains, and Great Basin in North America. These four species are the Coastal, Westslope, Lahontan, and the Rocky Mountain. As a member of the genus Oncorhynchus, it is in the Pacific trout group, which includes the widely distributed rainbow trout. Cutthroat trout are popular gamefish, especially among anglers who enjoy fly fishing. The common name "cutthroat" refers to the distinctive red coloration on the underside of the lower jaw. The specific name clarkii was given to honor explorer William Clark, coleader of the Lewis and Clark Expedition.
The Bitterroot River is a northward flowing 84-mile (135 km) river running through the Bitterroot Valley, from the confluence of its West and East forks near Conner in southern Ravalli County to its confluence with the Clark Fork River near Missoula in Missoula County, in western Montana. The Clark Fork River is a tributary to the Columbia River and ultimately, the Pacific Ocean. The Bitterroot River is a Blue Ribbon trout fishery with a healthy population of native westslope cutthroat trout and bull trout. It is the third most fly fished river in Montana behind the Madison and Big Horn Rivers.
Oncorhynchus is a genus of ray-finned fish in the subfamily Salmoninae of the family Salmonidae, native to coldwater tributaries of the North Pacific basin. The genus contains twelve extant species, namely six species of Pacific salmon and six species of Pacific trout, all of which are migratory mid-level predatory fish that display natal homing and semelparity.
Redband trout are a group of three recognized subspecies of rainbow trout. They occur in three distinct regions in Pacific basin tributaries and endorheic basins in the western United States. The three subspecies are the Columbia River redband trout, the McCloud River redband trout and the Great Basin redband trout.
The Snake River fine-spotted cutthroat trout is a form of the cutthroat trout that is considered either as a separate subspecies O. c. behnkei, or as a variety of the Yellowstone cutthroat trout. The fish takes its common name from its original habitat, the Snake River of southern Idaho and western Wyoming, and from its unusual pattern of hundreds of small spots that cover most of its body, differing from the larger-spotted Yellowstone cutthroat pattern. Genetically, it cannot be distinguished from the Yellowstone cutthroat trout, and before the construction of dams, no physical barriers were between the ranges of the two subspecies in the Snake River drainage.
The coastal cutthroat trout, also known as the sea-run cutthroat trout, blue-back trout or harvest trout, is one of the four species of cutthroat trout found in Western North America. The coastal cutthroat trout occurs in four distinct forms. A semi-anadromous or sea-run form is the most well known. Freshwater forms occur in both large and small rivers and streams and lake environments. The native range of the coastal cutthroat trout extends south from the southern coastline of the Kenai Peninsula in Alaska to the Eel River in Northern California. Coastal cutthroat trout are resident in tributary streams and rivers of the Pacific basin and are rarely found more than 100 miles (160 km) from the ocean.
The Rio Grande cutthroat trout, a member of the family Salmonidae, is found in northern New Mexico and southern Colorado in tributaries of the Rio Grande.
The cutbow is an interspecific fertile hybrid between rainbow trout and cutthroat trout. While natural separation of spawning habitat limited hybridization in most native populations of rainbow and cutthroat trout, introduction of non-native hatchery-raised rainbow trout into native cutthroat trout range increased hybridization across the landscape. Due to these introductions, many populations of cutthroat trout are at risk of genetic pollution. As a result, significant management intervention at state and federal levels has occurred to preserve native populations of cutthroat trout.
The Baja California rainbow trout or San Pedro Martir trout or Nelson's trout is a localized subspecies of the rainbow trout, a freshwater fish in the family Salmonidae.
The Humboldt cutthroat trout is a subspecies of cutthroat trout, a North American fish in the family Salmonidae. It is one of the several subspecies of cutthroat trout. It was formally scientifically named in 2008 by Trotter and Behnke, who stated its distribution is in the basins of the upper Humboldt River of northern Nevada, the Upper Quinn River, as well as the Whitehorse (Coyote) basin (Oregon). The Nevada and Oregon Fish and Wildlife authorities still consider these populations belonging to the subspecies O. c. henshawi.
The Willow-Whitehorse Basin cutthroat trout refers to a population segment of the cutthroat trout complex from the streams of the Whitehorse Basin, southeastern Oregon. It is alternatively considered as a part of the Lahontan cutthroat trout subspecies, or of the Humboldt cutthroat trout whose main range is in Nevada. These fish have adapted to live under extreme conditions, and can withstand water temperatures as high as 85 °F for short periods of time.
Dr. Robert J. Behnke 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 "The Trout Doctor". His seminal work, Trout and Salmon of North America, was published in 2002. He wrote a regular column for Trout Magazine, the quarterly publication of Trout Unlimited. He was a fisheries biologist with the U.S. Fish and Wildlife Service in the Colorado Cooperative Fish and Wildlife Research Unit and a professor at Colorado State University in the 1970s. He became a Professor Emeritus at the Department of Fishery and Wildlife Biology at Colorado State University.
Mexican native trout —Mexican rainbow trout, sometimes Baja rainbow trout and Mexican golden trout —occur in the Pacific Ocean tributaries of the Baja California peninsula and in the Sierra Madre Occidental of northwestern Mexico as far south as Victoria de Durango in the state of Durango. Many forms of the Mexican rainbow trout, subspecies of the rainbow trout, have been described. The Mexican golden trout is a recognized species.
The Rocky Mountain cutthroat trout(Oncorhynchus virginalis), formerly lumped in with the cutthroat trout as one species with multiple subspecies, is a fish species of the family Salmonidae native to cold-water tributaries of the northern and southern Rocky Mountains, as well as into portions of the Great Basin in North America. As a member of the genus Oncorhynchus, it is a part of the Pacific trout group, which includes the widely distributed rainbow trout. Cutthroat trout are popular gamefish, especially among anglers who enjoy fly fishing. The common name "cutthroat" refers to the distinctive red coloration on the underside of the lower jaw.