The coastal cutthroat trout (Oncorhynchus clarkii clarkii), also known as the sea-run cutthroat trout, blue-back trout or harvest trout, is one of the several subspecies 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 (160km) from the ocean.
Adults migrate from the ocean to spawn in fresh water. Juveniles migrate to the sea where they feed and become sexually mature before returning to fresh water to overwinter and spawn. Unlike steelhead and Pacific salmon, coastal cutthroat do not make lengthy migrations out to sea. Generally speaking, coastal cutthroat will remain in or near estuarine waters, usually within 5–10 miles (8.0–16.1km) of their natal stream. Some cutthroat, however, have been shown to move as far as 70 miles (110km) into the open ocean. There are also lacustrine and riverine populations that spend their entire lives in freshwater. One such population is the trout of Lake Crescent in Washington state that was formerly considered to be a separate subspecies called the Lake Crescent cutthroat trout, Oncorhynchus clarkii crescenti.
Taxonomy
Cutthroat trout were given the name Salmo clarkii in honor of William Clark, who co-led the expedition of 1804–1806.[2] 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 from a tributary of the lower Columbia River, identified as the "Katpootl",[2] 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.[3] In 1989, morphological and genetic studies by Gerald R. Smith, the Curator of Fishes at the Museum of Zoology, and Ralph F. Stearley, a doctoral candidate at Museum of Paleontology (University of Michigan) indicated trout of the Pacific basin were genetically closer to Pacific salmon (Oncorhynchus species) than to the Salmos–brown trout (S.trutta) or Atlantic salmon (S.salar) of the Atlantic basin.[4] Thus, in 1989, taxonomic authorities moved the rainbow, cutthroat and other Pacific basin trout into the genus Oncorhynchus.[5]
Description
Freshwater forms of the coastal cutthroat trout are generally dark green to greenish-blue on back, olive-green on upper flank, silvery on lower flank and belly. They display more numerous flank spots below lateral line, irregular spots on dorsal, adipose and caudal fins and the anal, pectoral and pelvic fin bases. The gill covers are pinkish. Sea-run forms while in salt water and shortly after returning to fresh water are silvery with a bluish back, yellowish lower flanks and fins, and display sparse spots. Cutthroats usually display distinctive red, pink, or orange linear marks along the undersides of their mandibles in the lower folds of the gill plates. These markings are responsible for the common name "cutthroat" given to the trout by outdoor writer Charles Hallock in an 1884 article in The American Angler.,[6] although the red slashes are not unique to the cutthroat trout and some coastal rainbow trout and redband trout also display throat slashes. The sea-run forms of coastal cutthroat average 2 to 5lb (0.9 to 2.3kg), while stream-resident forms attain much smaller sizes 0.4 to 3.2oz (11 to 91g).
Lifecycle
Coastal cutthroat trout usually inhabit and spawn in small to moderately large, clear, well-oxygenated, shallow rivers with gravel bottoms. They are native to the alluvial or freestone streams that are typical tributaries of the Pacific Basin. They typically spawn from December through June, with peak spawning in February. Eggs begin to hatch within six to seven weeks of spawning. Spawning begins when water temperatures reach 43 to 46°F (6 to 8°C). Depending on temperature, alevins emerge as fry between March and June, with peak emergence in mid-April.[3] Lake-resident coastal 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.[3]
Cutthroat trout naturally interbreed with the closely related rainbow trout, producing fertile hybrids commonly called "cutbows" although this is a much rarer occurrence with the coastal cutthroat trout because of reproductive isolation as the coastal cutthroat trout is the only cutthroat subspecies to coevolve through its entire range with the coastal rainbow trout (O.mykiss irideus). As this hybrid generally bears similar coloration and overall appearance to the cutthroat, retaining the characteristic orange-red slash, these hybrids often pose a taxonomic difficulty.[7]
Range and habitat
Typical northwest saltwater estuary environment for cutthroat trout, Quillayute River, Washington
The Necanicum River, a coastal waterway, typical sea-run cutthroat habitat
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 (160km) from the ocean.[8] Semi-anadromous, stream resident, fluvial and lake resident forms exist.[8] The great majority of coastal cutthroat trout habitat coincides with the belt of Pacific coast coniferous rainforest that extends from Alaska southward into Northern California.[9]
Coastal cutthroat trout use a large variety of habitat types, including lower and upper reaches of both large and small river systems, estuaries, sloughs, ponds, lakes, and near shore ocean waters. They spend more time in fresh water environments than other anadromous Pacific salmonids. In fresh water they prefer deeper pool habitat and cover, such as that formed by woody debris. The semi-anadromous forms of coastal cutthroat trout do not overwinter in saltwater and rarely make extended migrations across large bodies of water. Migrations in the marine environment are usually within 6 miles (9.7km) of land. Semi-anadromous coastal cutthroat typically spend two to five years rearing in fresh water before making their initial migration into saltwater. Generally, semi-anadromous coastal cutthroat trout spend short periods offshore during summer months and return to estuaries and fresh water by fall or winter.[10]
Conservation status
The coastal cutthroat is a secure subspecies of the cutthroat trout. Although there has been a general population decline of the sea-run form throughout its native range since the 19th century, none of the populations in the United States or British Columbia are considered threatened or endangered. The U.S. Fish and Wildlife Service, in cooperation with the U.S. Environmental Protection Agency, National Marine Fisheries Service and state wildlife agencies has designated ten distinct population segments (DPS) from Alaska to California.[11][12] A comprehensive status review of the DPSs in 1999 determined that only one DPS, the Southwestern Washington/Columbia River DPS be proposed for threatened status under the Endangered Species Act. On July 5, 2002, after lengthy public comment and scientific evaluation, the U.S. Fish and Wildlife service withdrew its proposal to list the Southwestern Washington/Columbia River DPS as threatened.[12]
Stream resident, fluvial and lake forms are secure within their native range and supplemented by stocking of hatchery raised fish in Washington and Oregon.
Notes
Angling for cutthroat trout in Puget Sound
↑ NatureServe (4 August 2023). "Oncorhynchus clarkii clarkii". NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer. Arlington, Virginia: NatureServe. Retrieved 20 August 2023.
1 2 3 Behnke, Robert J.; Tomelleri, Joseph R. (illustrator) (2002). "Cutthroat trout Oncorhynchus clarki". Trout and Salmon of North America. The Free Press. pp.137–234. ISBN0-7432-2220-2.
↑ Behnke, Robert J.; Tomelleri, Joseph R. (illustrator) (2002). "Genus Oncorhynchus". Trout and Salmon of North America. The Free Press. pp.10–21. ISBN0-7432-2220-2.
↑ Trotter, Patrick C. (2008). Cutthroat: Native Trout of the West (2nded.). Berkeley, CA: University of California Press. p.13. ISBN978-0-520-25458-9.
1 2 Behnke, Robert J.; Tomelleri, Joseph R. (illustrator) (2002). "Coastal Cutthroat Trout Oncorhynchus clarki clarki". Trout and Salmon of North America. The Free Press. pp.149–154. ISBN0-7432-2220-2.
↑ Trotter, Patrick C. (2008). "Coastal Cutthroat Trout". Cutthroat: Native Trout of the West (2nded.). Berkeley, CA: University of California Press. pp.59–101. ISBN978-0-520-25458-9.
Johnson, Les (1976). Sea-run Cutthroat Trout. Portland, OR: Frank Amato Publishers. ISBN978-0-936608-02-0.
Johnson, Les (2004). Fly-Fishing Coastal Cutthroat Trout: Flies, Techniques, Conservation. Portland, OR: Frank Amato Publishers. ISBN978-1-57188-334-6.
Trotter, Patrick C. (2008). Cutthroat: Native Trout of the West (2nded.). Berkeley, CA: University of California Press. ISBN978-0-520-25458-9.
Suckley, G. (Spring 1980). Raymond, Steve (ed.). "Sea-Run Cutthroats"(PDF). The American Fly Fisher. 7 (2). American Museum of Fly Fishing: 30–31. Archived from the original(PDF) on 2014-11-29. Retrieved 2014-11-21.
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 Asia and North America. 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.
Steelhead, or occasionally steelhead trout, is the anadromous form of the coastal rainbow trout (Oncorhynchus mykiss irideus) or Columbia River redband trout. Steelhead are native to cold-water tributaries of the Pacific basin in Northeast Asia and North America. Like other sea-run (anadromous) trout and salmon, steelhead spawn in freshwater, smolts migrate to the ocean to forage for several years and adults return to their natal streams to spawn. Steelhead are iteroparous, although survival is approximately 10–20%.
The cutthroat trout(Oncorhynchus clarkii) is a fish species of the family Salmonidae native to cold-water tributaries of the Pacific Ocean, Rocky Mountains, and Great Basin in North America. As a member of the genus Oncorhynchus, it is one of the Pacific trout, a group that 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 Bonneville cutthroat trout is a subspecies of cutthroat trout native to tributaries of the Great Salt Lake and Sevier Lake. Most of the fish's current and historic range is in Utah, but they are also found in Idaho, Wyoming, and Nevada. This is one of 14 or so recognized subspecies of cutthroat trout native to the western United States.
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.
The Alvord cutthroat trout, Oncorhynchus clarkii alvordensis, was a subspecies of cutthroat trout. It was known only from Trout Creek in Oregon and Virgin Creek in Nevada, although it may have lived in several of the larger Alvord Basin streams during recent times. It was native to spring-fed creeks that ran down to Alvord Dry Lake in southeast Oregon, which was a large lake during the ice ages and an isolated drainage, part of the Great Basin today. This is one of the two cutthroat trout taxa considered extinct because all known populations are hybridized with rainbow trout which were introduced into streams in the Alvord basin in the 1920s, resulting in cutbows.
Lahontan cutthroat trout is the largest subspecies of cutthroat trout, and the state fish of Nevada. It is one of three subspecies of cutthroat trout that are listed as federally threatened.
The Yellowstone cutthroat trout is a subspecies of the cutthroat trout. It is a freshwater fish in the salmon family. Native only to a few U.S. states, their original range was upstream of Shoshone Falls on the Snake River and tributaries in Wyoming, also across the Continental Divide in Yellowstone Lake and in the Yellowstone River as well as its tributaries downstream to the Tongue River in Montana. The species is also found in Idaho, Utah and Nevada.
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 greenback cutthroat trout is the easternmost subspecies of cutthroat trout. The greenback cutthroat, once widespread in the Arkansas and South Platte River drainages of Eastern Colorado and Southeast Wyoming, today occupies less than 1% of its historical range. It is currently listed as threatened under the Endangered Species Act. It was adopted as the state fish of Colorado on March 15, 1994, replacing the unofficial rainbow trout.
The westslope cutthroat trout, also known as the black-spotted trout, common cutthroat trout and red-throated trout is a subspecies of the cutthroat trout and is a freshwater fish in the salmon family of order Salmoniformes. The cutthroat is the Montana state fish. This subspecies is a species of concern in its Montana and British Columbia ranges and is considered threatened in its native range in Alberta.
The Crescenti cutthroat trout or the Lake Crescent cutthroat trout is a North American freshwater fish, a local form of the coastal cutthroat trout isolated in Lake Crescent in Washington. While previously attributed to a distinct subspecies Oncorhynchus clarkii crescenti, it is not currently recognized at the subspecies rank. However the cutthroat trout of Lake Crescent do remain distinct. They have the highest known gill raker and vertebrae counts of any coastal cutthroat population. The cutthroat are believed to have been isolated in Lake Crescent after a landslide blocked the eastern outflow of the lake.
Paiute cutthroat trout is one of fourteen subspecies of cutthroat trout. Paiute Cutthroat are native only to Silver King Creek, a headwater tributary of the Carson River in the Sierra Nevada, in California. This subspecies is named after the indigenous Northern Paiute peoples.
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.
A cutbow is an interspecific fertile hybrid between a rainbow trout and a cutthroat trout. Cutbow hybrids may occur naturally where the native ranges of both species overlap, such as between coastal rainbow trout and coastal cutthroat trout and between Columbia River redband trout and westslope cutthroat trout. While natural separation of spawning habitat limited hybridization in most native populations of rainbows and cutthroats, introduction of non-native hatchery-raised rainbow trout into the native ranges of cutthroat subspecies increased the rate of hybridization. Some native cutthroat populations are, as a result, at risk due to genetic pollution.
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.
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