Trout (: trout) is a generic common name for numerous species of carnivorous freshwater 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 (Cynoscion nebulosus, which is actually a croaker).
Trout are closely related to salmon and have similar migratory life cycles. Most trout are strictly potamodromous, spending their entire lives exclusively in freshwater lakes, rivers and wetlands and migrating upstream to spawn in the shallow gravel beds of smaller headwater creeks. The hatched fry and juvenile trout, known as alevin and parr, will stay upstream growing for years before migrating down to larger waterbodies as maturing adults. There are some anadromous species of trout, such as the steelhead (a coastal subspecies of rainbow trout) and sea trout (the sea-run subspecies of brown trout), that can spend up to three years of their adult lives at sea before returning to freshwater streams for spawning, in the same fashion as a salmon run. Brook trout and three other extant species of North American trout, despite the names, are actually char (or charr), which are salmonids also closely related to trout and salmon.
Trout are classified as oily fish and have been important food fish for humans. As mid-level predators, trout prey upon smaller aquatic animals including crustaceans, insects, worms, baitfish and tadpoles, and themselves in turn are also important staple prey items for many animals, including brown bears, otters, raccoons, birds of prey (e.g. sea eagles, ospreys, fish owls), gulls, cormorants and kingfishers, and other large aquatic predators. Discarded remains of trout also provide a source of nutrients for scavengers, detrivores and riparian florae, making trout keystone species across aquatic and terrestrial ecosystems.
Species The name "trout" is commonly used for many (if not most) species in three of the seven genera in the subfamily Salmoninae: Salmo (Atlantic), Oncorhynchus (Pacific) and Salvelinus (circum-arctic). Fish species referred to as trout include:
Genus Salmo, all extant species except Atlantic salmon Adriatic trout, Salmo obtusirostris Brown trout, Salmo trutta River trout, S. t. morpha fario Lake trout/Lacustrine trout, S. t. morpha lacustris Sea trout, S. t. morpha trutta Flathead trout, Salmo platycephalus Marble trout, Soca River trout or Soča trout – Salmo marmoratus Ohrid trout, Salmo letnica, S. balcanicus (extinct), S. lumi, and S. aphelios Sevan trout, Salmo ischchan
Genus Oncorhynchus, six of the 12 extant species Apache trout, Oncorhynchus apache Biwa trout, Oncorhynchus masou rhodurus Cutthroat trout, Oncorhynchus clarki Coastal cutthroat trout, O. c. clarki Crescenti trout, O. c. c. f. crescenti Alvord cutthroat trout, O. c. alvordensis (extinct) Bonneville cutthroat trout, O. c. utah Humboldt cutthroat trout, O. c. humboldtensis Lahontan cutthroat trout, O. c. henshawi Whitehorse Basin cutthroat trout Paiute cutthroat trout, O. c. seleniris Snake River fine-spotted cutthroat trout, O. c. behnkei Westslope cutthroat trout, O. c. lewisi Yellowfin cutthroat trout, O. c. macdonaldi (extinct) Yellowstone cutthroat trout, O. c. bouvieri Colorado River cutthroat trout, O. c. pleuriticus Greenback cutthroat trout, O. c. stomias Rio Grande cutthroat trout, O. c. virginalis Gila trout, Oncorhynchus gilae Rainbow trout, Oncorhynchus mykiss Kamchatkan rainbow trout, Oncorhynchus mykiss mykiss Columbia River redband trout, Oncorhynchus mykiss gairdneri Coastal rainbow trout (steelhead), Oncorhynchus mykiss irideus Beardslee trout, Oncorhynchus mykiss irideus var. beardsleei Great Basin redband trout, Oncorhynchus mykiss newberrii Golden trout, Oncorhynchus mykiss aguabonita Kern River rainbow trout, Oncorhynchus mykiss aguabonita var. gilberti Sacramento golden trout, Oncorhynchus mykiss aguabonita var. stonei Little Kern golden trout, Oncorhynchus mykiss aguabonita var. whitei Kamloops rainbow trout, Oncorhynchus mykiss kamloops Baja California rainbow trout, Nelson's trout, or San Pedro Martir trout, Oncorhynchus mykiss nelsoni Eagle Lake trout, Oncorhynchus mykiss aquilarum McCloud River redband trout, Oncorhynchus mykiss stonei Sheepheaven Creek redband trout Mexican golden trout, Oncorhynchus chrysogaster
Genus Salvelinus, five of the 52 extant species Brook trout, Salvelinus fontinalis Aurora trout, S. f. timagamiensis Bull trout, Salvelinus confluentus Dolly Varden trout, Salvelinus malma Lake trout, Salvelinus namaycush Silver trout, † Salvelinus agassizi (extinct) Hybrids Tiger trout, Salmo trutta X Salvelinus fontinalis (infertile) Speckled Lake (Splake) trout, Salvelinus namaycush X Salvelinus fontinalis (fertile)
Fish from other families Pseudaphritidae Genus Pseudaphritis Sand trout, Pseudaphritis urvillii Sciaenidae Genus Cynoscion Spotted sea-trout, Cynoscion nebulosus
Anatomy Trout that live in different environments can have dramatically different colorations and patterns. Mostly, these colors and patterns form as camouflage, based on the surroundings, and will change as the fish moves to different habitats. Trout in, or newly returned from the sea, can look very silvery, while the same fish living in a small stream or in an alpine lake could have pronounced markings and more vivid coloration; it is also possible that in some species, this signifies that they are ready to mate. In general, trout that are about to breed have extremely intense coloration and can look like an entirely different fish outside of spawning season. It is virtually impossible to define a particular color pattern as belonging to a specific breed; however, in general, wild fish are claimed to have more vivid colors and patterns.
Trout have fins entirely without spines, and all of them have a small adipose fin along the back, near the tail. The pelvic fins sit well back on the body, on each side of the anus. The swim bladder is connected to the esophagus, allowing for gulping or rapid expulsion of air, a condition known as physostome. Unlike many other physostome fish, trout do not use their bladder as an auxiliary device for oxygen uptake, relying solely on their gills.
There are many species, and even more populations, that are isolated from each other and morphologically different. However, since many of these distinct populations show no significant genetic differences, what may appear to be a large number of species is considered a much smaller number of distinct species by most ichthyologists. The trout found in the eastern United States are a good example of this. The brook trout, the aurora trout, and the (extinct) silver trout all have physical characteristics and colorations that distinguish them, yet genetic analysis shows that they are one species, Salvelinus fontinalis.
Lake trout (Salvelinus namaycush), like brook trout, belong to the char genus. Lake trout inhabit many of the larger lakes in North America, and live much longer than rainbow trout, which have an average maximum lifespan of seven years. Lake trout can live many decades, and can grow to more than .
Habitat
As salmonids, trout are coldwater fish that are usually found in cool (), clear streams, wetlands and lakes, although many of the species have anadromous populations as well. Juvenile trout are referred to as troutlet, troutling or parr. They are distributed naturally throughout North America, northern Asia and Europe. Several species of trout were introduced to Australia and New Zealand by amateur fishing enthusiasts in the 19th century, effectively displacing and endangering several upland native fish species. The introduced species included brown trout from England and rainbow trout from California. The rainbow trout has a steelhead subspecies, generally accepted as coming from Sonoma Creek. The rainbow trout of New Zealand still show the steelhead tendency to run up rivers in winter to spawn.
In Australia, the rainbow trout was introduced in 1894 from New Zealand and is an extremely popular gamefish in recreational angling. Despite severely impacting the distribution and abundance of native Australian fish, such as the climbing galaxias, millions of rainbow and other trout species are released annually from government and private hatcheries.
The closest resemblance of seema trout and other trout family can be found in the Himalayan Region of India, Nepal, Bhutan, Pakistan and in Tian Shan mountains of Kyrgyzstan.
Diet
Trout generally feed on other fish, and soft-bodied aquatic invertebrates, such as flies, mayflies, caddisflies, stoneflies, mollusks and dragonflies. In lakes, various species of zooplankton often form a large part of the diet. In general, trout longer than about prey almost exclusively on fish, where they are available. Adult trout will devour smaller fish up to one-third of their length. Trout may feed on shrimp, mealworms, bloodworms, insects, small animal parts, and eel.
Trout who swim the streams love to feed on land animals, aquatic life, and flies. Most of their diet comes from macroinvertebrates, or animals that do not have a backbone like snails, worms, or insects. They also eat flies, and most people who try to use lures to fish trout mimic flies because they are one of trout's most fed on meals. Trout enjoy certain land animals, including insects like grasshoppers. They also eat small animals like mice when they fall in. (Although only large trout have mouths capable of eating mice.) They consume a diet of aquatic life like minnows or crawfish as well. Trout have a diverse diet they follow; they have plenty of different options.
Trout as food
Compared to other salmonids, trout are somewhat more bony, but the flesh is generally considered delicious, and the texture is often indistinguishable from that of salmon. The flavor of the flesh is heavily influenced by the diet of the fish. For example, trout that have been feeding on crustaceans tend to be more flavorful than those feeding primarily on insects and larvae. Because of their popularity, trout are often raised on fish farms and then stocked into heavily fished waters, in an effort to mask the effects of overfishing. Farmed trout are also sold commercially as seafood, although they are not saltwater fish. Trout meat is typically prepared the same way as salmon, often by smoking.
In Mainland China, farm-raised rainbow trout from Qinghai was officially sanctioned to be labeled and sold domestically as salmon, which caused controversy in 2018 regarding food safety and consumer rights violation, as raw fish dishes or yusheng using Atlantic salmon are gaining popularity in southern China. Farmed rainbow trout is much cheaper than the imported Atlantic salmon and the meat are indistinguishable to the untrained eyes, and the news of trout being sold as salmon triggered public scrutiny accusing seafood suppliers of bait-and-switch and unethical business practices. Also, many people believe freshwater trout are more prone to parasites than oceanic salmon (even though both live in freshwater for significant periods of their life cycles) and thus unsafe for raw eating.
Nutritional value One fillet of trout (about ) contains: Energy: Fat (g): 5.22 Carbohydrates (g): 0 Fibers (g): 0 Protein (g): 16.41 Cholesterol (mg): 46
Trout fishing