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151-511: The freshwater form of the steelhead is the rainbow trout ( Oncorhynchus mykiss ). The difference between these forms of the species is that steelhead migrate to the ocean and return to freshwater tributaries to spawn, whereas non-anadromous rainbow trout do not leave freshwater. Steelhead are also larger and less colorful than rainbow trout. Steelhead can weigh up to 55 lb (25 kg) and reach 45 in (110 cm) in length. They can live up to 11 years and spawn multiple times. The body of

302-590: A 2016 an action plan implementation progress report stated the population is "maintained" showing no significant upward or downward trend in the yearly number of returning adults in a experimental small tributary to the Deschutes River. However, fish counts at Boneville Dam, on the Columbia River below the Deschutes confluence have shown a 10 year (2013–2022) average of 162,988 returning adults, and

453-620: A 25% increase in salmon and steelhead production was 20%" (NOAA). As it stands, "more than 20% of floodplain and in-channel habitat has been restored due to FRGP" (NOAA). Though these initiatives spell hope for the prospects of Steelhead Trout population rehabilitation, habitat degradation continues to occur at an alarming rate. Within the state of Oregon there are four different distinct steelhead population segments: Lower Columbia River steelhead, Middle Columbia River steelhead, Oregon Coast steelhead, and Upper Willamette River Steelhead (NOAA). Of these four segments, three are listed as threatened under

604-399: A bed of fine gravel in a riffle above a pool. A female trout clears a redd in the gravel by turning on her side and beating her tail up and down. Female rainbow trout usually produce 2000 to 3000 4-to-5-millimetre ( 5 ⁄ 32 – 3 ⁄ 16  in) eggs per kilogram of weight. During spawning, the eggs fall into spaces between the gravel, and immediately the female begins digging at

755-464: A breeding site. The females choose large males that are successfully defending prime breeding sites which the females find attractive. For example, sculpin males defend "caves" underneath rocks which are suitable for the incubation of embryos. Another way males get to mate with several females is through the use of leks. Leks are places where many fish come together, and the males display to each other. Based on these displays, each female then selects

906-754: A broad reddish stripe along the lateral line , from gills to the tail, which is most vivid in breeding males. Wild-caught and hatchery -reared forms of the species have been transplanted and introduced for food or sport in at least 45 countries and every continent except Antarctica. Introductions to locations outside their native range in the United States, Southern Europe, Australia, New Zealand, and South America have damaged native fish species. Introduced populations may affect native species by preying on them, out-competing them, transmitting contagious diseases (such as whirling disease ), or hybridizing with closely related species and subspecies. The rainbow trout

1057-418: A century ago, but its range has spread and it has appeared in most of Europe, northern Asia, the U.S., South Africa and other countries. In the 1980s, M. cerebralis was found to require Tubifex tubifex (a kind of segmented worm ) to complete its life cycle . The parasite infects its hosts with its cells after piercing them with polar filaments ejected from nematocyst -like capsules. This parasite

1208-651: A century of hatchery stocking. Genetic analysis shows that the South Central California Coast and Southern California populations from Malibu Creek north, including the San Gabriel River , Santa Ana River , and San Mateo Creek , are not hatchery strains. Steelhead from Topanga Creek and the Sweetwater River were partly, and those from San Juan Creek completely, of hatchery origin. Genetic analysis has also shown that

1359-422: A chemical indicator, steelhead "use the position of the sun and magnetic north to navigate towards spawning grounds " after they have fed in the open ocean for 1–4 whole years (Fulton). Even after traveling hundreds of miles, this chemical imprint allows steelhead to identify their precise hatching grounds upon returning to freshwater. According to "A review of the characteristics, habitat requirements, and ecology of

1510-480: A classification of the spawning behaviours of fish by Balon (1975, 1984) into reproductive guilds . This classification is based on how the eggs are fertilized (internal or external spawners), where the eggs are deposited ( pelagic or benthic spawners), and whether and how the parents look after the eggs after spawning (bearers, guarders and nonguarders). Nonguarders do not protect their eggs and offspring after spawning Open substrate spawners scatter their eggs in

1661-618: A decline or even elimination of whole cohorts of fish. The parasite M. cerebralis was first recorded in North America in 1956 in Pennsylvania, but until the 1990s, whirling disease was considered a manageable problem affecting only rainbow trout in hatcheries. It eventually became established in the natural waters of the Rocky Mountain states ( Colorado , Wyoming, Utah , Montana , Idaho , New Mexico ), where it

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1812-406: A drop of nutrient oil to sustain the embryo as it develops inside the egg case. The oil also provides buoyancy, so the eggs float and drift with the current. The strategy for survival of broadcast spawning is to disperse the fertilised eggs, preferably away from the coast into the relative safety of the open ocean. There the larvae develop as they consume their fat stores, and eventually hatch from

1963-772: A few days and replace the dominant male. This is found amongst coral reef fishes such as groupers , parrotfishes and wrasses . It is less common for a male to switch to a female ( protandry ). As an example, most wrasses are protogynous hermaphrodites within a haremic mating system. Hermaphroditism allows for complex mating systems. Wrasses exhibit three different mating systems: polygynous, lek-like , and promiscuous mating systems. Group spawning and pair spawning occur within mating systems. The type of spawning that occurs depends on male body size. Labroids typically exhibit broadcast spawning, releasing high amounts of planktonic eggs, which are broadcast by tidal currents; adult wrasses have no interaction with offspring. Wrasse of

2114-840: A forage fish of the smelt family found in the Atlantic and Arctic oceans. In summer, they graze on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat krill and other crustaceans . The capelin move inshore in large schools to spawn and migrate in spring and summer to feed in plankton rich areas between Iceland , Greenland , and Jan Mayen . The migration is affected by ocean currents . Around Iceland maturing capelin make large northward feeding migrations in spring and summer. The return migration takes place in September to November. The spawning migration starts north of Iceland in December or January. The diagram on

2265-2357: A four year (2019–2022) average of 97,352, suggesting a recent decline in rates of returning adults. Aaron Fulton. "A Review of the Characteristics, Habitat Requirements, and Ecology of the Anadromous Steelhead Trout (Oncorhynchus Mykiss) in the Skeena Basin," June 15, 2004, 16. "Coastal Multispecies Plan Volume III: Northern California Steelhead." NOAA Fisheries, 2016. https://www.fisheries.noaa.gov/resource/document/final-coastal-multispecies-recovery-plan-california-coastal-chinook-salmon. "Coastal Rainbow Trout/ Steelhead." California Department of Fish and Wildlife, October 29, 2016. https://wildlife.ca.gov/Conservation/Fishes/Coastal-Rainbow-Trout-Steelhead. "Fish Hatcheries." In Fishing in Idaho . Idaho Department of Fish and Game, n.d. https://idfg.idaho.gov/visit/hatchery. Peter B. Moyle, Joshua A. Israel, and Sabra E. Purdy. "Salmon, Steelhead, and Trout in California: Status of an Emblematic Fauna." California Trout , 2008, 220. "Rainbow Trout and Steelhead." National Wildlife Federation, n.d. https://www.nwf.org/Educational-Resources/Wildlife-Guide/Fish/Rainbow-Trout-Steelhead. "Southern Steelhead: A Story of Recovery." California Trout, February 7, 2018. https://caltrout.org/news/southern-steelhead-story-recovery. "Steelhead Trout." Salmon Fishing Now, 2018. https://www.salmonfishingnow.com/steelhead-trout-biology/. "Steelhead Trout." In NOAA Fisheries . NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, n.d. https://www.fisheries.noaa.gov/species/steelhead-trout. "Steelhead Trout Identification." King County, November 10, 2016. https://www.kingcounty.gov/services/environment/animals-and-plants/salmon-and-trout/identification/steelhead.aspx. V. Kuhnlein, Harriet, and Murray M. Humphries. "Rainbow Trout (Steelhead Trout)." In Traditional Animal Foods of Indigenous Peoples of Northern North America . Centre for Indigenous Peoples' Nutrition and Environment, n.d. http://traditionalanimalfoods.org/fish/freshwater/page.aspx?id=6151. Rainbow trout This

2416-437: A generally appealing flavor. Seafood Watch ranks farmed rainbow trout as a "Best Choice" fish for human consumption. In Montana , it is illegal to sell or market wild-caught rainbow trout, which are legally classified as game fish. The color and flavor of the flesh depend on the diet and freshness of the trout. Farmed trout and some populations of wild trout, especially anadromous steelhead, have reddish or orange flesh as

2567-518: A normal rainbow trout. The longer a steelhead spends in freshwater, the darker their green body colorations and horizontal pink stripe become. When a steelhead exits the river and returns to the ocean again, it regains its silvery appearance while in saltwater. The fish develop a larger and stronger tail relative to a normal rainbow trout to help aid in swimming in ocean currents and swimming up strong river currents. A number of distinct population segments of steelhead are endangered or threatened across

2718-400: A pair of gonads , which release sperm in response to hormones in the female's bloodstream indicating egg release. This ensures that, when the female is ready to spawn, she has a mate immediately available. A single anglerfish female can "mate" with many males in this manner. Polygynandry occurs when multiple males mate indiscriminately with multiple females. This mutual promiscuity is

2869-503: A particular subgroup of the family Labridae , Labrini, do not exhibit broadcast spawning. Less commonly hermaphrodites can be synchronous , meaning they simultaneously possess both ovaries and testicles and can function as either sex at any one time. Black hamlets "take turns releasing sperm and eggs during spawning. Because such egg trading is advantageous to both individuals, hamlets are typically monogamous for short periods of time–an unusual situation in fishes." The sex of many fishes

3020-749: A rainbow trout species that can be completely fed on a vegan diet through genetic selection. Research from a study team led by USDA research geneticist Dr. Ken Overturf concluded that such natural genetic variation of vegan trouts does exist and believe they can produce rainbow trouts that can be completely fed on a 100% plant-based diet. Populations of many rainbow trout subspecies, including anadromous forms (steelhead) of O. m. irideus (coastal rainbow trout) and O. m. gairdneri (Columbia River redband trout), have declined in their native ranges due to over-harvest, habitat loss, disease, invasive species , pollution and hybridization with other subspecies, and some introduced populations, once healthy, have declined for

3171-603: A recent sighting of the Steelhead Trout has not occurred in years, and biologists fear the worst. In 2002, the endangered species label was extended from the Malibu Creek down to the border of San Diego and Mexico (California Trout). A threatened species since 2000, the Northern California steelhead represents a beacon of hope for continued rehabilitation initiatives and growing population numbers in

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3322-488: A relatively small number of embryos and retain them for a few weeks to 16 months or longer. The shorter times spans are characteristic of species that eventually deposit their embryos in the environment, surrounded by a horny capsule; whereas the longer periods are characteristic of sharks that retain the embryos until they are ready to emerge as actively swimming young." However, some fish do not fit these categories. The livebearing largespring gambusia ( Gambusia geiseri )

3473-641: A result of high astaxanthin levels in their diets. Astaxanthin is a powerful antioxidant that may be from a natural source or a synthetic trout feed. Rainbow trout raised to have pinker flesh from a diet high in astaxanthin are sometimes sold in the U.S. with labeling calling them "steelhead". As wild steelhead are in decline in some parts of their range, farmed rainbow trout are viewed as a preferred alternative. In Chile and Norway , rainbow trout farmed in saltwater sea cages are sold labeled as steelhead. Trout can be cooked as soon as they are cleaned, without scaling , skinning , or filleting . If cooked with

3624-423: A result of such biologically accurate homing characteristics, the Steelhead Trout is "uniquely adapted to its environment"; fish populations "are reasonably isolated from fish that spawn in different areas," and therefore "sub-populations may differ by the timing of runs, size of fish, and even behavior patterns" (Heath, 2001). This also influences genetic relatedness between Steelhead Trout populations; interestingly,

3775-400: A significant temperature change, often in spring. Males chase females, prompting them to release their eggs by bumping and nudging them. As the female goldfish spawns her eggs, the male goldfish stays close behind fertilizing them. Their eggs are adhesive and attach to aquatic vegetation. The eggs hatch within 48 to 72 hours. Within a week or so, the fry begins to assume its final shape, although

3926-650: A similar latitude. The range of coastal rainbow trout ( O. m. irideus ) extends north from the Pacific basin into tributaries of the Bering Sea in northwest Alaska, while forms of the Columbia River redband trout ( O. m. gairdneri ) extend east into the upper Mackenzie River and Peace River watersheds in British Columbia and Alberta, Canada, which eventually drain into the Beaufort Sea , part of

4077-605: A species is all-male or all-female. Unisexuality occurs in some fish species, and can take complex forms. Squalius alburnoides , a minnow found in several river basins in Portugal and Spain, appears to be an all-male species. The existence of this species illustrates the potential complexity of mating systems in fish. The species originated as a hybrid between two species, and is diploid , but not hermaphroditic. It can have triploid and tetraploid forms, including all-female forms that reproduce mainly through hybridogenesis . It

4228-423: A species is either male or female, and remains that way throughout their lives. Most fish are gonochorists, but hermaphroditism is known to occur in 14 families of teleost fishes. Usually hermaphrodites are sequential , meaning they can switch sex, usually from female to male ( protogyny ). This can happen if a dominant male is removed from a group of females. The largest female in the harem can switch sex over

4379-484: A steel beam are attributed as the main defining physical characteristic for which the Steelhead is distinguished and earns its namesake. The Steelhead is an ocean-going predatory fish with a typical lifespan of four to six years. Like the common rainbow trout, Steelhead predominantly feast on zooplankton when they are young and then transition to eating fish, some rodents, mollusks, and crustaceans. When these fish enter

4530-438: A substrate and guard them until the eggs hatch. After hatching, the female picks up the fry and keeps them in her mouth. When the fry can fend for themselves, they are released. Some eartheaters are larvophile mouthbrooders. The beginning of the evolutionary process of livebearing starts with facultative (optional) internal bearing. The process occurs in several species of oviparous (egg-laying) killifishes which spawn in

4681-644: A wider distribution of this species across the Pacific Northwest, including the coastal regions of California. In fact, "coastal rainbow trout is the most widely-distributed native trout form" (CA.gov). Among other necessary biological utilities fulfilled by this species, Steelhead Trout "are also strong indicators of the condition of California's streams; large self-sustaining populations of native salmon and trout are found where streams are in reasonably good condition" (Moyle, Israel, & Purdy, 2008). A chrome underside and olive-grey back reminiscent to that of

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4832-437: A year may pass before they develop a mature goldfish colour; until then they are a metallic brown like their wild ancestors. In their first weeks of life, the fry grow quickly—an adaptation born of the high risk of getting devoured by the adult goldfish. Carp typically spawn in the spring and summer, depending on the climate and conditions. Oxygen levels of the water, availability of food, size of each fish, age, number of times

4983-544: Is a non-profit organization dedicated to the conservation of North American freshwater streams, rivers, and associated upland habitats for trout, salmon, other aquatic species, and people. A typical TU project is the Circle Creek Fish Passage Project, in which access to a spawning stream is being improved for steelhead and other salmonid species. The Wild Salmon Center , an international coalition of Russian, Canadian and U.S. scientists, sponsors

5134-444: Is an "investment by parents in offspring that increases the offspring's chances of surviving (and hence reproducing). In fish, parental care can take a variety of forms including guarding, nest building, fanning, splashing, removal of dead eggs, retrieval of straying fry, external egg carrying, egg burying, moving eggs or young, ectodermal feeding, oral brooding, internal gestation, brood-pouch egg carrying, etc." Territorial behaviour

5285-533: Is an accepted version of this page The rainbow trout ( Oncorhynchus mykiss ) is a species of trout native to cold-water tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout ) 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

5436-615: Is called coral because it turns bright red when cooked. Roe (reproductive organs) are usually eaten either raw or briefly cooked. "The reproductive behaviour of fishes is remarkably diversified: they may be oviparous (lay eggs), ovoviviparous (retain the eggs in the body until they hatch), or viviparous (have a direct tissue connection with the developing embryos and give birth to live young). All cartilaginous fishes—the elasmobranches (e.g., sharks, rays, and skates)—employ internal fertilization and usually lay large, heavy-shelled eggs or give birth to live young. The most characteristic features of

5587-571: Is common. Rainbow trout can also be caught on various live and dead natural baits . Many anglers consider the rainbow trout the hardest-fighting trout species, as this fish is known for leaping when hooked and putting up a powerful struggle. It is considered one of the top five sport fish in North America, and the most important game fish west of the Rocky Mountains . There are tribal commercial fisheries for steelhead in Puget Sound ,

5738-448: Is completely consumed, and fry commence feeding mainly on zooplankton . The growth rate of rainbow trout varies with area, habitat, life history, and quality and quantity of food. As fry grow, they begin to develop "parr" marks or dark vertical bars on their sides. In this juvenile stage, immature trout are often called "parr" because of the marks. These small juvenile trout are sometimes called 'fingerlings' because they are approximately

5889-594: Is considered a threatened species, and according to Mark Capelli of the National Marine Fisheries Service, the Southern California steelhead are the most endangered of them all (California Trout). According to California Trout, Steelhead Trout populations began to decline in the "late-1940s due mainly to man-made landscape modifications" (California Trout). As a result of damming for flood control, steelhead migration routes from

6040-467: Is damaging several sport fishing rivers. Some streams in the western U.S. lost 90 percent of their trout. Whirling disease threatens recreational fishing, which is important for the tourism industry, a key component of the economies of some U.S. western states. For example, in 2005 anglers in Montana spent approximately $ 196,000,000 in activities directly related to trout fishing in the state. Some of

6191-408: Is difficult for fish to find partners, or when both sexes look after the young. Many tropical cichlids , which rear their young together in locations where they must fiercely defend against competitors and predators are monogamous. "In some pipefishes and seahorses , development of eggs takes a long time before the female can place them in the brood pouch of a male, where they are fertilized. While

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6342-610: Is dominated by large and aggressive males. Cuckoldry is a variant of polyandry, and can occur with sneak spawners (sometimes called streak spawners ). A sneak spawner is a male that rushes in to join the spawning rush of a spawning pair. A spawning rush occurs when a fish makes a burst of speed, usually on a near vertical incline, releasing gametes at the apex, followed by a rapid return to the lake or sea floor or fish aggregation. Sneaking males do not take part in courtship. In salmon and trout, for example, jack males are common. These are small silvery males that migrate upstream along with

6493-482: Is evidence North American fishes are unable to digest the tiny but hard shells of the mud snail, and that their presence may result in poor growth outcomes for rainbow trout. The mud snail was first detected in the U.S. in Idaho's Snake River in 1987. Since then, the snail has spread to the Madison River , Firehole River, and other watercourses around Yellowstone National Park, and has been discovered throughout

6644-489: Is generally necessary for guarders, and the embryos are almost always guarded by males (apart from cichlids). There is a need to be territorial because looking after embryos usually includes defending the site where they are being looked after. It also often means there is competition for the best egg-laying sites. Elaborate courtship behaviour is usual among guarders. Guarding males keep the embryos safe from predators, keep oxygen levels high by fanning water currents, and keep

6795-489: Is included in the list of the top 100 globally invasive species . Other introductions into waters previously devoid of fish or with severely depleted stocks of native fish have created sport fisheries , such as the Great Lakes and Wyoming 's Firehole River . Some local populations of specific subspecies, or in the case of steelhead, distinct population segments , are listed as either threatened or endangered under

6946-561: Is isolated in Lake Crescent (Washington), is threatened by the loss of its only spawning grounds in the Lyre River to siltation and other types of habitat degradation. Myxobolus cerebralis is a myxosporean parasite of salmonids (salmon, trout, and their allies) that causes whirling disease in pen farmed salmon and trout and also in wild fish populations . It was first described in rainbow trout introduced to Germany

7097-450: Is not fixed, but can change with physical and social changes to the environment where the fish lives. Particularly among fishes, hermaphroditism can pay off in situations where one sex is more likely to survive and reproduce, perhaps because it is larger. Anemone fishes are sequential hermaphrodites which are born as males, and become females only when they are mature. Anemone fishes live together monogamously in an anemone , protected by

7248-517: Is often associated with r-strategists . However, most fish and other spawning animals are iteroparous. When the internal ovaries or egg masses of fish and certain marine animals are ripe for spawning they are called roe . Roe from certain species, such as shrimp , scallop , crab and sea urchins , are sought as human delicacies in many parts of the world. Caviar is a name for the processed, salted roe of non-fertilized sturgeon . The term soft roe or white roe denotes fish milt . Lobster roe

7399-494: Is often necessary to construct fish ladders and other bypass systems so salmon can navigate their way past hydroelectric dams or other obstructions such as weirs on their way to spawning grounds. Coastal fish often use mangroves and estuaries as spawning grounds, while reef fish can find adjacent seagrass meadows that make good spawning grounds. Short-finned eels can travel anything up to three or four thousand kilometres to their spawning ground in deep water somewhere in

7550-569: Is popular in Western cuisine ; both wild-caught and farmed fish are eaten. It has tender flesh and a mild, somewhat nutty flavor. Wild fish has a stronger, gamier taste than farmed fish. While the taste of wild-caught trout is often promoted as superior, rainbow trout and "steelhead" sold in American restaurants is typically farmed . Farmed rainbow trout are considered one of the safest fish to eat and are noted for high levels of vitamin B and

7701-509: Is rare to find true parthenogenesis in fishes, where females produce female offspring with no input from males. All-female species include the Texas silverside , Menidia clarkhubbsi as well as the Amazon molly . Parthenogenesis has been recently observed in hammerhead sharks and blacktip sharks . It is also known to occur in crayfish and amphibians. This section is patterned after

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7852-503: Is the egg yolk, as in externally spawned eggs. This situation, also referred to as ovoviviparity , is characteristic of marine rock fishes and the Lake Baikal sculpins . This strategy allows these fish to have fecundities approaching those of pelagic fish with external fertilization, but it also enables them to protect the young during their most vulnerable stage of development. By contrast, sharks and rays using this strategy produce

8003-530: The Au Sable River . "Wild" populations of these fish started to become established shortly after their introduction into the lakes. By the late 80s populations could be found in notable rivers like the Muskegon and Pere Marquette . Sometime after their first introduction into Michigan tributaries other states, such as New York, Ohio, and Pennsylvania, started stocking fish into their own streams. Due to

8154-615: The Columbia River who provided Richardson with specimens. In 1855, William P. Gibbons, the curator of Geology and Mineralogy at the California Academy of Sciences , found a population and named it Salmo iridia (Latin: rainbow), later corrected to Salmo irideus . These names faded once it was determined that Walbaum's description of type specimens was conspecific and therefore had precedence . In 1989, morphological and genetic studies indicated that trout of

8305-618: The Coral Sea . Forage fish often make great migrations between their spawning, feeding and nursery grounds. Schools of a particular stock usually travel in a triangle between these grounds. For example, one stock of herrings have their spawning ground in southern Norway , their feeding ground in Iceland , and their nursery ground in northern Norway. Wide triangular journeys such as these may be important because forage fish, when feeding, cannot distinguish their own offspring. Capelin are

8456-634: The Endangered Species Act . The steelhead is the official state fish of Washington . The scientific name of the rainbow trout is Oncorhynchus mykiss . The species was originally named by German naturalist and taxonomist Johann Julius Walbaum in 1792 based on type specimens from the Kamchatka Peninsula in Siberia. Walbaum's original species name, mykiss , was derived from the local Kamchatkan name used for

8607-599: The Pacific Basin were genetically closer to Pacific salmon ( Oncorhynchus species) than to the Salmo s – brown trout ( Salmo trutta ) or Atlantic salmon ( Salmo salar ) of the Atlantic Basin . Thus, in 1989, taxonomic authorities moved the rainbow, cutthroat , and other Pacific Basin trout into the genus Oncorhynchus . Walbaum's name had precedence, so the species name Oncorhynchus mykiss became

8758-474: The United States , mostly caused by the blocking of waterways by the construction of dams . Human interaction has had considerable consequences on reducing the population of steelhead trout. Steelhead currently support or have historically supported fisheries across Northern California, and thus they hold "economic as well as cultural value" (Moyle, Israel, & Purdy, 2008). Contrary to popular belief,

8909-502: The Washington coast, and in the Columbia River , but there has been controversy regarding overharvesting of native stocks . The highly desirable sporting qualities and adaptability of the rainbow trout to hatchery rearing and new habitats resulted in it being introduced to many countries around the world by or at the behest of sport fishermen. Many of these introductions have resulted in environmental and ecological problems, as

9060-712: The adipose fin is a management tool used to identify hatchery-reared fish. Rainbow trout, including steelhead forms, generally spawn in early to late spring (January to June in the Northern Hemisphere and September to November in the Southern Hemisphere) when water temperatures reach at least 6 to 7 °C (42 to 44 °F). The maximum recorded lifespan for a rainbow trout is 11 years. Freshwater resident rainbow trout usually inhabit and spawn in small to moderately large, well-oxygenated, shallow rivers with gravel bottoms. They are native to

9211-518: The alluvial or freestone streams that are typical tributaries of the Pacific basin but introduced rainbow trout have established wild, self-sustaining populations in other river types such as bedrock and spring creeks . Lake-resident rainbow trout are usually found in moderately deep, cool lakes with adequate shallows and vegetation to support the production of sufficient food sources. Lake populations generally require access to gravelly-bottomed streams to be self-sustaining. Spawning sites are usually

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9362-570: The bluegill sunfish in fresh water. Sneaker males that become too large to hide effectively become satellite males . With bluegill sunfish, satellite males mimic the behaviour and colouration of the females. They hover over a nest containing a pair of courting sunfish, and gradually descend to reach the pair just as they spawn. Males may need to be 6 or 7 years old to function capably as parental males, but may be able to function as sneaker or satellite males when they are as young as 2 or 3 years old. The smaller satellite and sneaker males may get mauled by

9513-675: The mitochondria are the most important organelle contributing to tissue damage because of their role in metabolism and production of reactive oxygen species . In a study done by Almaida-Pagàn et al., researchers identified changes to the heart and brain mitochondrial membrane phospholipid composition in rainbow trout due to the differing levels of oxidative stress each organ faced during a high-stress time such as rapid growth and development. Stock rainbow trout of ages 1, 2, and 4 years had their heart and brain mitochondria isolated and analyzed for fatty acid composition. The tissues showed an overall similar percentage of total phospholipids but differed in

9664-662: The sardine run occurs when millions of sardines migrate from their spawning grounds south of the southern tip of Africa northward along the Eastern Cape coastline. Chinook salmon make the longest freshwater migration of any salmon, over 3,000 kilometres (1,900 mi) up the Yukon River to spawning grounds upstream of Whitehorse , Yukon. Some green sea turtles swim more than 2,600 kilometres (1,600 mi) to reach their spawning grounds. Goldfish , like all cyprinids , are egg-layers. They usually start breeding after

9815-546: The 3,400 km (2,100 mi) river system. Neither method of control is 100% effective and are best regarded as methods to change the relative population sizes of fish species. Steelhead populations in parts of its native range have declined due to a variety of human and natural causes. While populations in Alaska and along the British Columbia coast are considered healthy, populations in Kamchatka and some populations along

9966-461: The Anadromous Steelhead Trout" by Fulton, "homing creates genetically different subpopulations that differ by basin, stream, and even location within a stream" (Altukhov 2000). According to a study conducted by Heath & Pollard, "significant genetic variation on the individual, tributary, and watershed level occur between Steelhead Trout populations" as a result of this chemical reliance for breeding practices (Heath, 2001). The author concludes that as

10117-499: The Arctic Ocean. Since 1875, the rainbow trout has been widely introduced into suitable lacustrine and riverine environments throughout the United States and around the world. Many of these introductions have established wild, self-sustaining populations. Since 1870, rainbow trout have been artificially propagated in fish hatcheries to restock streams and introduce them into non-native waters. The first rainbow trout hatchery

10268-561: The California Steelhead is a coastal variation of the same species of fish as the Rainbow Trout, Oncorhynchus mykiss ; "rainbow trout are the 'landlocked' version, and remain in freshwater throughout their life" (King County, 2016) . An ocean-going variety, the Steelhead, or Oncorhynchus mykiss irideus has developed unique adaptive characteristics that distinguish this fish from its common counterpart and have allowed

10419-1029: The Endangered Species Act. The Middle Columbia River (MCR) segment has remained the focus of recent recovery efforts. The MCR segment covers approximately 3,500 square miles of the Columbia Plateau in eastern Oregon and Washington. Within eastern Oregon, recovery efforts focus on the two main tributaries to the Columbia River: The Deschutes River and the John Day River, although the Umatilla and Walla Walla are also included in recovery plans. Primary threats to MCR steelhead populations include hydrosystem operations, habitat alteration, and effects of stray naturally spawning hatchery fish. MCR steelhead were first listed as threatened on March 25, 1999, following

10570-691: The Garmat Ali River in Iraq since 2008 ), Europe (since 1859 in England), and North America (U.S. and Canada: Thunder Bay in Ontario since 2001, British Columbia since July 2007 ), most likely inadvertently during human activity. It can reach concentrations greater than 500,000 per square metre (46,000/sq ft), endangering the food chain by outcompeting native snails and water insects for food, leading to sharp declines in native populations. There

10721-399: The Great Lakes is as high as 70 percent. As young steelhead transition from freshwater to saltwater, a process called " smoltification " occurs where the trout undergoes physiological changes to allow it to survive in seawater. There are genetic differences between freshwater and steelhead populations that may account for the smoltification in steelhead. Juvenile steelhead may remain in

10872-577: The Kamchatka Steelhead Project, a 20-year (1994–2014) scientific program to study and conserve the present condition of Kamchatkan steelhead ("mikizha"), a species listed in the Red Data Book of Russia . Other high-profile organizations involved in rainbow trout conservation include California Trout , which protects wild trout and other salmonids in the waters of California. The Steelhead Society of British Columbia promotes

11023-824: The Pacific basin, from the Kamchatka Peninsula in Russia, east along the Aleutian Islands , throughout southwest Alaska, the Pacific coast of British Columbia and southeast Alaska, and south along the west coast of the U.S. to northern Mexico. It is claimed that the Mexican forms of Oncorhynchus mykiss represent the southernmost native range of any trout or salmon ( Salmonidae ), though the Formosan landlocked salmon ( O. masou formosanus ) in Asia inhabits

11174-508: The U.S. West Coast are in decline. The U.S. National Marine Fisheries Service has 15 identified distinct population segments , in Washington , Oregon , and California. Eleven of these populations are listed under the U.S. Endangered Species Act , ten as threatened and one as endangered. One distinct population segment on the Oregon coast is designated a U.S. Species of Concern . The Southern California distinct population segment , which

11325-654: The U.S. by the Environmental Protection Agency . Once the chemicals have dissipated, native trout are released into the river. Another method is to use electrofishing which enables the fish to be caught alive and harvested or re-located. This technique has been used in the Great Smokey Mountains National Park to rid it of rainbow trout that were introduced in the 1930s and have thrived ever since. They are hoping to re-establish native brook trout in at least some of

11476-598: The U.S., Iran, Turkey, the United Kingdom, and Lesotho . While the U.S. rainbow trout industry as a whole is viewed as ecologically responsible, trout raised elsewhere are not necessarily farmed with the same methods. About three-quarters of U.S. production comes from Idaho, particularly the Snake River area, due in part to the quality and temperature of the water available there. California and Washington also produce significant numbers of farmed trout. In

11627-511: The U.S., and nearly all domestic production is consumed within the country; very little is exported. The U.S. produces about 7 percent of the world's farmed trout. Rainbow trout, especially those raised in farms and hatcheries, are susceptible to enteric redmouth disease . A considerable amount of research has been conducted on redmouth disease, given its serious implications for rainbow trout farming. The disease does not infect humans. There have been recent interest and efforts in introducing

11778-496: The U.S., there are hundreds of hatcheries operated by the United States Fish and Wildlife Service and various state agencies and tribal governments propagating rainbow trout for conservation and recreational sport fishing. Six of ten Canadian provinces have rainbow trout farms, with Ontario leading production. Rainbow trout are commercially farmed in many countries throughout the world. The practice began in

11929-678: The Upper Deschutes, Crooked, and Metolius rivers, three major tributaries to the Deschutes within the MCR watershed. In addition to Round Butte, several other dams restrict fish from their native spawning grounds within the Deschutes watershed including Pelton Dam, Bowman Dam, and Ochoco Dam. The first MCR Distinct Population Segment ESA Recovery Plan was released on November 30, 1999. Between 2010 and 2016 1,715 different entities have implemented 1,559 tributary restoration projects primarily focused on habitat restoration and fish passage improvement. In

12080-472: The anemone stings. The males do not have to compete with other males, and female anemone fish are typically larger. When a female dies a juvenile (male) anemone fish moves in, and "the resident male then turns into a female and reproductive advantages of the large female–small male combination continue". In other fishes sex changes are reversible. For example, if some gobies are grouped by sex (male or female), some will switch sex. Unisexuality occurs when

12231-420: The approach most commonly used by spawning animals, and is perhaps the "original fish mating system." Common examples are forage fish , such as herrings , which form huge mating shoals in shallow water. The water becomes milky with sperm and the bottom is draped with millions of fertilized eggs. Alternate male strategies which allow small males to engage in cuckoldry can develop in species where spawning

12382-448: The area free from dead embryos and debris. They protect the embryos until they hatch, and often look after the larval stages as well. The time spent guarding can range from a few days to several months. Some guarders build nests ( nest spawners ) and some do not ( substrate spawners ), though the difference between the two groups can be small. Substrate spawners clean off a suitable area of surface suitable for egg laying, and look after

12533-432: The area, but they do not actively build a nest. Bearers are fish that carry their embryos (and sometimes their young) around with them, either externally or internally. Mouth brooders - carry eggs or larvae in their mouth. Mouth brooders can be ovophiles or larvophiles. Ovophile or egg-loving mouth-brooders lay their eggs in a pit, which are sucked up into the mouth of the female. The small number of large eggs hatch in

12684-927: The area. As of 2016, 48,892 Steelhead Trout were reportedly caught (NOAA). Such a population count suggests that this fascinating fish species continue to persevere in Northern California waters. However, to ensure the continued rehabilitation of steelhead populations in Northern California, a positive, directive plan of action for steelhead conservation must occur. According to NOAA, The State of California Fisheries Restoration Grant Program (FRGP) "invested over 250 million dollars and supported approximately 3,500 salmonid restoration projects" (NOAA). Investments in projects improving "fish passage, water quality, instream habitat restoration, watershed monitoring, and education and organizational support" all occupy conservation efforts to improve Northern California steelhead populations (NOAA). According to NOAA, "the percentage of floodplain and in-channel habitat that would need to be restored to detect

12835-429: The author found that the genetic similarity of regional Steelhead trout populations "is correlated with distance" (Heath, 2001). During spawning , the fish will lay their eggs on gravel bottoms of freshwater tributaries. The female digs out a hole called a redd. The preferred depth for steelhead spawning is 6 to 14 inches (150 to 360 mm). She then lays the eggs, and a male fertilizes them. The females will then cover

12986-433: The bottom of rivers and streams in late winter. It is not considered a significant human health risk, but it can affect stream habitats and sources of food for fish, including rainbow trout, and make recreational activities unpleasant. Even though it is native in North America, it is considered a nuisance organism or invasive species. Enteric redmouth disease is a bacterial infection of freshwater and marine fish caused by

13137-477: The brooding but cannot handle all the eggs the female produce, such as with some pipefish . The males in some deep sea anglerfishes are much smaller than the females. When they find a female they bite into her skin, releasing an enzyme that digests the skin of their mouth and her body and fusing the pair down to the blood-vessel level. The male then slowly atrophies , losing first his digestive organs, then his brain, heart, and eyes, ending as nothing more than

13288-485: The case of the westslope cutthroat trout ( O. clarki lewisi ), hybridization with introduced rainbow and Yellowstone cutthroat trout ( O. clarki bouvieri ) is threatening the westslope cutthroat trout with genomic extinction . Such introductions into the ranges of redband trout ( O. m. gairdneri , newberrii , and stonei ) have severely reduced the range of pure stocks of these subspecies, making them "species of concern" in their respective ranges. Within

13439-531: The coast to upstream spawning grounds were increasingly blocked over time (California Trout). Furthermore, largely a result of continued urbanization and to satisfy the needs of human populations in the area, river flows became modified for recreational purposes and a substantial diversion of water occurred over time (California Trout). As a result of widespread habitat loss and fragmentation, Southern California Steelhead populations were officially labeled as an endangered species in 1997 (California Trout). In some areas,

13590-462: The construction of Round Butte Dam at the confluence of the Deschutes and Metolius rivers. The construction of the dam created reverse currents (currents flowing upstream) in the Metolius Arm of Lake Billy Chinook (a reservoir created by the formation of the dam) confusing anadromous smolts and preventing them from navigating seaward. The construction of Round Butte Dam impeded steelhead access to

13741-456: The east, Pennsylvania , North Carolina and West Virginia have farming operations. Rainbow trout farming is one of the largest finfish aquaculture industries in the U.S. They are raised inland in facilities where raceways or ponds have continuously flowing water with little pollution and a low risk of escape. The U.S. industry is noted for using best management practices . Imports constitute only about 15 percent of farmed rainbows sold in

13892-450: The egg capsule into miniature versions of their parents. To survive, they must then become miniature predators themselves, feeding on plankton. Fish eventually encounter others of their own kind ( conspecifics ), where they form aggregations and learn to school. Internally, the sexes of most marine animals can be determined by looking at the gonads . For example, male testes of spawning fish are smooth and white and account for up to 12% of

14043-407: The eggs of other rainbow trout. Rainbows also consume decomposing flesh from the carcasses of other fish. They have even been observed to have consumed hatchling snakes, such as the barred grass snake ( Natrix helvetica ). Adult steelhead in the ocean feed primarily on other fish, squid and amphipods . The native range of Oncorhynchus mykiss is in the coastal waters and tributary streams of

14194-472: The eggs with the gravel. Depending on the size of the female she may lay up to 9,000 eggs. The female then buries the eggs in a foot of gravel. The eggs remain in the gravel until they hatch. Unlike salmon (which can spawn only once) steelhead may return to the ocean, and come back upstream several times for spawning season. Steelhead found in the Great Lakes are the freshwater variation of steelhead found in saltwater. Similar to native populations of steelhead on

14345-507: The environment. They usually spawn in shoals without complex courtship rituals, and males outnumber females. Broadcast spawners : release their gametes (sperm and eggs) into open water for external fertilisation. There is no subsequent parental care. About 75% of coral species are broadcasters, the majority of which are hermatypic, or reef-building corals. Brood hiders hide their eggs but do not give parental care after they have hidden them. Brood hiders are mostly benthic spawners that bury

14496-532: The fertilized eggs. For example, among salmon and trout the female digs a nest with her tail in gravel. These nests are called redds . The female then lays her eggs while the male fertilizes them, while both fish defend the redd if necessary from other members of the same species. Then the female buries the nest, and the nest site is abandoned. In North America, some minnows build nests out of piles of stones rather than dig holes. The minnow males have tubercles on their head and body which they use to help them defend

14647-671: The first federal fish hatchery in the National Fish Hatchery System , was established on Campbell Creek, a McCloud River tributary. The McCloud River hatchery indiscriminately mixed coastal rainbow trout eggs with the eggs of local McCloud River redband trout ( O. m. stonei ) . Eggs from the McCloud hatchery were also provided to the San Leandro hatchery, thus making the origin and genetic history of hatchery-bred rainbow trout somewhat diverse and complex. In

14798-520: The fish spend more time in the tributaries they darken in coloration while developing a bright red stripe down their midline. While in the lakes they feed on alewives , smelt , and lake herring amongst other things. The first introduction of steelhead into the Great Lakes dates back to 1876 where smolts were taken from wild populations from the McCloud River in California and placed into

14949-463: The fish, mykizha . The name of the genus is from the Greek ὄγκος ( ónkos ) "lump, bend, hook" and ῥύγχος ( rhúnkhos ) " snout ", in reference to the hooked jaws of males in the mating season (the " kype "). Sir John Richardson , a Scottish naturalist, named a specimen of this species Salmo gairdneri in 1836 to honor Meredith Gairdner, a Hudson's Bay Company surgeon at Fort Vancouver on

15100-523: The following groups: As a general rule, aquatic or semiaquatic reptiles , birds , and mammals do not reproduce through spawning, but rather through copulation like their terrestrial counterparts. This is also true of cartilaginous fishes (such as sharks , rays and skates ). Spawn consists of the reproductive cells ( gametes ) of many aquatic animals, some of which will become fertilized and produce offspring. The process of spawning typically involves females releasing ova (unfertilized eggs) into

15251-415: The host. The same female may use a number of mussels, and she deposits only one or two yellow, oval eggs into each. Early developmental stages are protected from predation within the body of the mussel. After 3 to 4 weeks larvae swim away from the host to continue life on their own. Guarders protect their eggs and offspring after spawning by practicing parental care (also called brood care ). Parental care

15402-468: The impassable barriers; a 2007 genetic study of fin samples collected from steelhead at 20 different sites both above and below passage barriers in the watershed found that although 30 million hatchery trout were stocked in the river from 1911 to 1925, the steelhead remain of native and not hatchery origin. Releases of conventionally reared hatchery steelhead pose ecological risks to wild steelhead populations. Hatchery steelhead are typically larger than

15553-603: The introduced rainbow trout disrupt local ecosystems and outcompete or prey upon indigenous fishes. Other introductions to support sport angling in waters either devoid of fish or with seriously depleted native stocks have created world-class fisheries such as in the Firehole River in Yellowstone National Park and in the Great Lakes . The International Game Fish Association recognizes

15704-546: The late 19th century, and since the 1950s commercial production has grown dramatically. Worldwide, in 2007, 604,695 tonnes (666,562 short tons) of farmed rainbow trout were harvested with a value of about US$ 2.6 billion. The largest producer is Chile. In Chile and Norway, sea 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, France, Germany, Denmark, and Spain. Other significant trout-producing countries include

15855-835: The length of the body. Adult fish have a broad reddish stripe along the lateral line, from gills to the tail, which is most pronounced in breeding males. The caudal fin is squarish and only mildly forked. Lake-dwelling and anadromous forms are usually more silvery in color with the reddish stripe almost completely gone. Juvenile rainbow trout display parr marks (dark vertical bars) typical of most salmonid juveniles. In some redband and golden trout forms, parr marks are typically retained into adulthood. Some coastal rainbow trout ( O. m. irideus ) and Columbia River redband trout ( O. m. gairdneri ) populations and cutbow hybrids may also display reddish or pink throat markings similar to cutthroat trout. In many regions, hatchery-bred trout can be distinguished from native trout via fin clips . Fin clipping

16006-470: The male is pregnant, the female starts a new batch of eggs, which are ready at about the same time that the male gives birth to the young from the previous mating. This close timing of development promotes monogamy, especially if the likelihood of encountering another potential mate is low." Polygyny occurs when one male gets exclusive mating rights with multiple females. In polygyny, a large conspicuous male usually defends females from other males or defends

16157-533: The male they want to be their mate. For example, among the cichlid Cyrtocara eucinostomus in Lake Malawi , up to 50,000 large and colourful males display together on a lek four kilometres long. The females, which are mouth brooders, choose which male they want to fertilize their eggs. Polyandry occurs when one female gets exclusive mating rights with multiple males. This happens among fish like clownfish that change their sex. It can also happen when males do

16308-498: The males often have penis-like intromittent organs in the form of a modified fin. A species is semelparous if its individuals spawn only once in their lifetime, and iteroparous if its individuals spawn more than once. The term semelparity comes from the Latin semel , once, and pario , to beget, while iteroparity comes from itero , to repeat, and pario , to beget. Semelparity is sometimes called "big bang" reproduction, since

16459-661: The mass of the fish, while female ovaries are granular and orange or yellow, accounting for up to 70% of the fish's mass. Male lampreys, hagfish and salmon discharge their sperm into the body cavity where it is expelled through pores in the abdomen. Male sharks and rays can pass sperm along a duct into a seminal vesicle , where they store it for a while before it is expelled, while teleosts usually employ separate sperm ducts. Externally, many marine animals, even when spawning, show little sexual dimorphism (difference in body shape or size) or little difference in colouration . Where species are dimorphic, such as sharks or guppies ,

16610-437: The more powerful parental males, but they spawn when they are younger and they do not put energy into parental care. Hermaphroditism occurs when a given individual in a species possesses both male and female reproductive organs, or can alternate between possessing first one, and then the other. Hermaphroditism is common in invertebrates but rare in vertebrates. It can be contrasted with gonochorism , where each individual in

16761-581: The more primitive bony fishes is the assemblage of polyandrous (many males) breeding aggregations in open water and the absence of parental care..." There are two main reproduction methods in fish. The first method is by laying eggs and the second by live-bearing (producing their young alive). Monogamy occurs when one male mates with one female exclusively. This is also called pair spawning . Most fish are not monogamous, and when they are, they often alternate with non-monogamous behaviours. Monogamy can occur when feeding and breeding grounds are small, when it

16912-426: The most interesting and perplexing characteristic of the Steelhead Trout is its homing behavior and the capacity of this species to accurately detect its primary spawning grounds despite venturing to the open ocean and returning to the same freshwater source on numerous occasions throughout their lives. By recording the concentrations of solutes and the chemical profile of a stream through the biological characteristic of

17063-434: The mother's mouth, and the fry remain there for a period of time. Fertilization often occurs with the help of egg-spots, which are colorful spots on the anal fin of the male. When the female sees these spots, she tries to pick up the egg-spots, but instead gets sperm that fertilizes the eggs in her mouth. Many cichlids and some labyrinth fish are ovophile mouthbrooders. Larvophile or larvae-loving mouth-brooders lay their eggs on

17214-399: The nest site. Bitterlings have a remarkable reproduction strategy where parents transfer responsibility for the care of their young to mussels . The female extends her ovipositor into the mantle cavity of the mussel and deposits her eggs between the gill filaments. The male then ejects his sperm into the mussel's inhalant water current and fertilization takes place within the gills of

17365-415: The normal way on the substrate, but in the process accidentally fertilize eggs that the female retains and does not spawn. These eggs are spawned later, usually without allowing much time for embryonic development. The next step in the evolution of livebearing is obligate (by necessity) internal bearing, where the female retains all the embryos. "The only source of nutrition for these embryos, however,

17516-417: The ocean. Freshwater forms that have been introduced into the Great Lakes and migrate into tributaries to spawn are also called steelhead. Adult freshwater stream rainbow trout average between 0.5 and 2.5 kilograms (1 and 5 lb), while lake-dwelling and anadromous forms may reach 9 kg (20 lb). Coloration varies widely based on subspecies , forms, and habitat . Adult fish are distinguished by

17667-447: The open ocean, however, their diet typically consists of squid, crustaceans, and small fish including anchovies, herring, and sardines, though the capacity at which this dietary intake occurs is highly contingent upon the geographical region where Steelhead choose to migrate (Salmon Fishing Now). "Rainbow trout and steelhead represent two divergent ecotypes that are genetically identical but separated by life history strategies" (Heath 2001);

17818-561: The pathogen Yersinia ruckeri . It is primarily found in rainbow trout and other cultured salmonids . The disease is characterized by subcutaneous hemorrhaging of the mouth, fins, and eyes. It is most commonly seen in fish farms with poor water quality. Redmouth disease was first discovered in Idaho rainbow trout in the 1950s. Some fisheries are focused on removing rainbow trout in order to reestablish native trout populations. This can be done by poisoning rivers with chemicals such as antimycin or rotenone which have been declared safe in

17969-537: The range of the Kern River golden trout of Southern California, hatchery-bred rainbows introduced into the Kern River have diluted the genetic purity of the Kern River rainbow trout (O. m. gilberti) and golden trout (O. m. aguabonita) through intraspecific breeding. The Beardslee trout ( O. m. irideus var. beardsleei ) , a genetically unique lake-dwelling variety of the coastal rainbow trout that

18120-458: The right shows the main spawning grounds and larval drift routes. Capelin on the way to feeding grounds is coloured green, capelin on the way back is blue, and the breeding grounds are red. In a paper published in 2009, researchers from Iceland recount their application of an interacting particle model to the capelin stock around Iceland, successfully predicting the spawning migration route for 2008. Referred to as "the greatest shoal on earth",

18271-471: The river for one to three years before smolting and migrating to sea. Individual steelhead populations leave the ocean and migrate into their freshwater spawning tributaries at different times of the year. Two general forms exist—"summer-run steelhead" and "winter-run steelhead". Summer-run fish leave the ocean between May and October before their reproductive organs are fully mature. They mature in freshwater while en route to spawning grounds where they spawn in

18422-504: The river landscape for recreation and access to water. It is estimated that only 500 steelhead trout return to the Southern California watersheds. However, in other areas of the United States, steelhead can be seen as pests because they are an invasive species to the environment. While numbers are improving in areas of the Pacific Northwest where Steelhead Trout have typically thrived, the California Steelhead Trout

18573-437: The salmonids that M. cerebralis infects ( bull trout , cutthroat trout, and anadromous forms of rainbow trout—steelhead) are already threatened or endangered, and the parasite could worsen their population decline. The New Zealand mud snail ( Potamopyrgus antipodarum ) , once endemic to New Zealand, has spread widely and has become naturalised and an invasive species in many areas including Australia, Asia (Japan, in

18724-796: The same reasons. As a consequence, some rainbow populations, particularly anadromous forms within their native range, have been classified as endangered , threatened or species of special concern by federal or state agencies. Rainbow trout, and subspecies thereof, are currently a U.S. Environmental Protection Agency -approved indicator species for acute freshwater toxicity testing. Many non-profit organizations have formed to protect, conserve and restore native rainbow trout and steelhead populations. Generally, in partnership with various universities, state, federal and tribal agencies, and private interests, these organizations sponsor projects to restore habitat, prevent habitat loss and promote awareness of threats to native trout populations. Trout Unlimited (TU)

18875-479: The same species. Like salmon, steelhead return to their original hatching grounds to spawn . Similar to Atlantic salmon, but unlike their Pacific Oncorhynchus 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, although fewer than 10 percent of native spawning adults survive from one spawning to another. The survival rate for introduced populations in

19026-829: The scientific name of the rainbow trout. The previous species names irideus and gairdneri were adopted as subspecies names for the coastal rainbow and Columbia River redband trout, respectively. Anadromous forms of the coastal rainbow trout ( O. m. irideus ) or Columbia River redband trout ( O. m. gairdneri ) are commonly known as steelhead . Subspecies of Oncorhynchus mykiss are listed below as described by fisheries biologist Robert J. Behnke (2002). Resident freshwater rainbow trout adults average between 0.5 and 2.5 kg (1 and 5 lb) in riverine environments, while lake-dwelling, and anadromous forms may reach 9 kg (20 lb). Coloration varies widely between regions and subspecies. Adult freshwater forms are generally blue-green or olive green with heavy black spotting over

19177-482: The single reproductive event of semelparous organisms is usually large and fatal to the spawners. The classic example of a semelparous animal is the Pacific salmon , which lives for many years in the ocean before swimming to the freshwater stream of its birth, spawning, and then dying. Other spawning animals which are semelparous include mayflies , squid , octopus , smelt , capelin and some amphibians. Semelparity

19328-530: The size of a human finger. In streams where rainbow trout are stocked for sport fishing, but no natural reproduction occurs, some of the stocked trout may survive and grow or "carryover" for several seasons before they are caught or perish. The oceangoing (anadromous) form, including those returning for spawning, are known as steelhead in Canada and the U.S. In Tasmania they are commercially propagated in sea cages and are known as ocean trout , although they are

19479-489: The skin on, the meat tends to hold together better. While trout sold commercially in Europe is often prepared and served this way, most trout sold commercially in the United States have the fish heads removed and have been fully or partially deboned and filleted. Medium to heavy-bodied white wines , such as chardonnay , sauvignon blanc , or pinot gris , are typical wine pairings for trout. In Mainland China since 2018, it

19630-406: The spawn is released and whether or how the spawn is subsequently guarded. Marine animals, and particularly bony fish , commonly reproduce by broadcast spawning . This is an external method of reproduction where the female releases many unfertilised eggs into the water. At the same time, a male or many males release a lot of sperm into the water which fertilises some of these eggs. The eggs contain

19781-917: The spring. Summer-run fish generally spawn in longer, more inland rivers such as the Columbia River. Winter-run fish are ready to spawn when they leave the ocean, typically between November and April, and spawn shortly after returning to fresh water. Winter-run fish generally spawn in shorter, coastal rivers typically found along the Olympic Peninsula and British Columbia coastline, and summer-run fish are found in some shorter, coastal streams. Once steelhead enter riverine systems and reach suitable spawning grounds, they spawn just like resident freshwater rainbow trout. During periods of rapid growth and aging, trout display high levels of metabolic activity. High metabolic activity has been correlated with increased levels of oxidative stress and decreased machinery repair in rainbow trout. During high oxidative stress,

19932-427: The standard, large, hook-nosed males and that spawn by sneaking into a redd (spawning nest) to release sperm simultaneously with a mated pair. This behaviour is an evolutionarily stable strategy for reproduction, because it is favoured by natural selection just like the "standard" strategy of large males. Cuckoldry occurs in many fish species, including dragonets , parrotfishes and wrasses on tropical reefs and

20083-545: The steelhead in the streams of the Santa Clara County and Monterey Bay basins are not of hatchery origin, including the Coyote Creek , Guadalupe River , Pajaro River , Permanente Creek , Stevens Creek , San Francisquito Creek , San Lorenzo River , and San Tomas Aquino Creek basins. Natural waterfalls and two major dams have isolated Russian River steelhead from freshwater rainbow trout forms above

20234-418: The steelhead trout is silvery and streamlined with a rounder head. This silver color and round head is what gives the steelhead its name. There are black dots that are more concentrated on the back of the fish and become sparser closer to the lateral line of the fish. Steelhead also develop a pink horizontal stripe. When steelhead return to freshwater to spawn, their color begins to more closely resemble that of

20385-402: The steelhead's large size and powerful demeanor, they've become very attractive amongst the angler community in the Great Lakes area. There have been several conservation programs created since the near extinction of the steelhead in the 1940s. The reduction in population is mainly due to manmade obstructions within river systems. This is usually caused by dams blocking access, or humans changing

20536-853: The trout's development into an adult, a time of intense growth, the mitochondrial membrane composition and fluidity changes, which can cause defects in the electron transport chain . These defects combined with altered machinery repair and reactive oxygen species may cause more detrimental effects on the mitochondria in the fish as it matures. Rainbow trout are predators with a varied diet and will eat nearly anything they can capture. They are not as piscivorous or aggressive as brown trout or chars . Rainbow trout, including juvenile steelhead in fresh water, routinely feed on larval , pupal , and adult forms of aquatic insects (typically caddisflies , stoneflies , mayflies and aquatic diptera ). They also eat fish eggs and adult forms of terrestrial insects (typically ants, beetles, grasshoppers, and crickets) that fall into

20687-422: The types and proportions of phospholipids. With age, the heart showed more unsaturated phospholipids, which are more susceptible to peroxidation, and thus, damage. The brain mitochondria of rainbow trout show decreased levels of docosahexaenoic acid and a lower peroxidation index, suggesting a lower susceptibility to damage by oxidative stress and a different reaction to growth compared to heart mitochondria. During

20838-448: The unique biological diversity of the Steelhead Trout from that of the Rainbow Trout is determined through a capacity to migrate to the open ocean. Homing behavior is a unique adaptation of Steelhead Trout that allows the fish to migrate to and from freshwater and saltwater bodies on multiple occasions. Through the process of imprinting, Steelhead Trout deposit a chemical indicator "that is specific to their natal stream" (NRC 1996). Perhaps

20989-409: The upstream edge of the nest, covering the eggs with the displaced gravel. As eggs are released by the female, a male moves alongside and deposits milt (sperm) over the eggs to fertilize them. The eggs usually hatch in about four to seven weeks although the time of hatching varies greatly with region and habitat. Newly hatched trout are called sac fry or alevin . In approximately two weeks, the yolk sac

21140-459: The water, as well as algae. Other prey includes small fish up to one-third of their length, crayfish , shrimp, and other crustaceans . As rainbow trout grow, the proportion of fish consumed increases in most populations. Some lake-dwelling forms may become planktonic feeders. In rivers and streams populated with other salmonid species, rainbow trout eat varied fish eggs, including those of salmon, brown and cutthroat trout, mountain whitefish , and

21291-428: The water, often in large quantities, while males simultaneously or sequentially release spermatozoa ( milt ) to fertilize the eggs. The fungi ( mushrooms ), are also said to "spawn" when they release a white, ‘fibrous’ matter, forming the matrix from-which they grow. There are many variations in the way spawning occurs, depending on sexual differences in anatomy, how the sexes relate to each other, where and how

21442-570: The wellbeing of wild salmonids in British Columbia. In 1997, a group of approximately 40 ichthyologists, biologists and naturalists from several U.S. and Mexican institutions formed a collaborative group—Truchas Mexicanas—to study the diversity of Mexican native trout , most of which are considered subspecies of O. mykiss . Rainbow trout, primarily hatchery-raised fish of the coastal rainbow trout subspecies ( O. m. irideus ) introduced into waters inhabited with cutthroat trout, will breed with cutthroats and produce fertile hybrids called cutbows. In

21593-594: The west coast, Great Lakes steelhead start in tributaries to larger bodies of water, in this case the Great Lakes, where they travel to, to grow to large proportions and reach sexual maturity before returning to the tributaries they started in. Great Lakes steelhead grow to as large as 20 pounds and 36–40 inches but normally average 4–10 pounds and between 20–30 inches. They share very similar characteristics to an ocean-run steelhead as far as their long, slender build and silvery coloration with spots running along their back that very rarely progress beyond their lateral line . As

21744-502: The western U.S. The exact means of transmission is unknown, but it is likely that it was introduced in water transferred with live game fish and has been spread by ship ballast or contaminated recreational equipment such as wading gear. Didymosphenia geminata , commonly known as didymo or rock snot, is a species of diatom that produces nuisance growths in freshwater rivers and streams with consistently cold water temperatures. In New Zealand, invasive didymo can form large mats on

21895-520: The wild forms and can displace wild-form juveniles from optimal habitats. The dominance of hatchery steelhead for optimal microhabitats within streams may reduce wild steelhead survival as a result of reduced foraging opportunities and increased rates of predation. Rainbow trout and steelhead are highly regarded game fish among anglers . Rainbow trout are a popular target for fly fishers , and several lure fishing methods are used. The use of lures presented via spinning, casting, or trolling techniques

22046-489: The world record for rainbow trout as a fish caught on Saskatchewan 's Lake Diefenbaker by Sean Konrad on September 5, 2009, which weighed 48 lb (22 kg). The record is controversial because the fish was a genetically modified triploid and was part of a large number of triploid rainbow trout which escaped from an aquaculture facility. Rainbow trout is sometimes used as a biological indicator for water quality in water purification facilities. Rainbow trout

22197-489: Was established on San Leandro Creek , a tributary of San Francisco Bay , in 1870, and trout production began in 1871. The hatchery was stocked with the locally native rainbow trout, and likely steelhead of the coastal rainbow trout subspecies ( O. m. irideus ) . The fish raised in this hatchery were shipped to hatcheries out of state for the first time in 1875, to Caledonia, New York , and then in 1876 to Northville, Michigan . In 1877, another California rainbow trout hatchery,

22348-622: Was listed as endangered in 2011, has been affected by habitat loss due to dams, confinement of streams in concrete channels, water pollution , groundwater pumping, urban heat island effects, and other byproducts of urbanization. Steelhead in the Kamchatka Peninsula are threatened by over-harvest, particularly from poaching and potential development, and are listed in the Red Data Book of Russia that documents rare and endangered species. Several studies have shown that almost all California coastal steelhead are of native origin, despite over

22499-526: Was originally a mild pathogen of brown trout in central Europe and other salmonids in northeast Asia, and the spread of the rainbow trout has greatly increased its impact. Having no innate immunity to M. cerebralis , rainbow trout are particularly susceptible, and can release so many spores that even more resistant species in the same area, such as Salmo trutta , can become overloaded with parasites and incur mortalities of 80 to 90 percent. Where M. cerebralis has become well-established, it has caused

22650-468: Was ruled by an industrial association that rainbow trout can be labelled and sold as salmon . Spawn (biology) Spawn is the eggs and sperm released or deposited into water by aquatic animals . As a verb, to spawn refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is known as spawning . The vast majority of aquatic and amphibious animals reproduce through spawning. These include

22801-548: Was thought to be ovoviviparous until it was shown in 2001 that the embryos received nutrients from the mother. Spawning grounds are the areas of water where aquatic animals spawn, or produce their eggs. After spawning, the spawn may or may not drift to new grounds which become their nursery grounds. Many species undertake migrations each year, and sometimes great migrations, to reach their spawning grounds. For example, lakes and river watersheds can be major spawning grounds for anadromous fish such as salmon . These days, it

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