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76-459: The Arctic char or Arctic charr ( Salvelinus alpinus ) is a cold-water fish in the family Salmonidae , native to alpine lakes , as well as Arctic and subarctic coastal waters in the Holarctic . It spawns in freshwater and its populations can be lacustrine , riverine , or anadromous , where they return from the ocean to their fresh water birth rivers to spawn. No other freshwater fish

152-535: A copepod species ( Calanis finmarchicus ) and krill ( Thysanoëssa ). Lake-dwelling Arctic chars feed mostly on insects and zoobenthos. Some giant Arctic chars have been recorded as cannibals of their young as well as dwarf Arctic chars. Spawning occurs over rocky shoals in lakes with heavy wave action and in slower gravel-bottom pools in rivers. As with most salmonids, vast differences in colouration and body shape occur between sexually mature males and females. Males develop hooked jaws known as kypes and take on

228-579: A crown group of ray-finned fish that can protrude their jaws . The tetrapods , a mostly terrestrial clade of vertebrates that have dominated the top trophic levels in both aquatic and terrestrial ecosystems since the Late Paleozoic , evolved from lobe-finned fish during the Carboniferous , developing air-breathing lungs homologous to swim bladders. Despite the cladistic lineage, tetrapods are usually not considered to be fish, making "fish"

304-579: A paraphyletic group and for this reason, the class Pisces seen in older reference works is no longer used in formal classifications. Traditional classification divides fish into three extant classes (Agnatha, Chondrichthyes, and Osteichthyes), and with extinct forms sometimes classified within those groups, sometimes as their own classes. Fish account for more than half of vertebrate species. As of 2016, there are over 32,000 described species of bony fish, over 1,100 species of cartilaginous fish, and over 100 hagfish and lampreys. A third of these fall within

380-426: A paraphyletic group. Fish have been an important natural resource for humans since prehistoric times, especially as food . Commercial and subsistence fishers harvest fish in wild fisheries or farm them in ponds or in breeding cages in the ocean. Fish are caught for recreation , or raised by fishkeepers as ornaments for private and public exhibition in aquaria and garden ponds . Fish have had

456-653: A brilliant red colour. Females remain fairly silver. Males are polygamous in sexual nature each season. They will circumambulate the females by rubbing up against them slightly. As the female lays her eggs, the male fertilizes her, which takes place during the daylight hours. Most males set up and guard territories and often spawn with several females. The female constructs the nest, or redd . A female anadromous char usually deposits from 3000 to 5000 eggs. Arctic char do not die after spawning like Pacific salmon , and often spawn several times throughout their lives, typically every second or third year. Young Arctic char emerge from

532-403: A case was made for more graded categorisations such as that of prehistoric natives , which occurred in a region during prehistory but have since suffered local extinction there due to human involvement. A native species in a location is not necessarily also endemic to that location. Endemic species are exclusively found in a particular place. A native species may occur in areas other than

608-528: A distinct size dimorphism, dwarf and giant. Dwarf Arctic char weigh between 0.2 and 2.3 kg (7 oz and 5 lb 1 oz) and average a length of 8 cm (3 in), while giant Arctic char weigh between 2.3 and 4.5 kg (5 lb 1 oz and 9 lb 15 oz) and average 40 cm (16 in) in length. Individual fish can weigh 9 kg (20 lb) or more with record-sized fish having been taken by anglers in Northern Canada , where it

684-548: A fish-like body shape through convergent evolution . Fishes of the World comments that "it is increasingly widely accepted that tetrapods, including ourselves, are simply modified bony fishes, and so we are comfortable with using the taxon Osteichthyes as a clade, which now includes all tetrapods". The biodiversity of extant fish is unevenly distributed among the various groups; teleosts , bony fishes able to protrude their jaws , make up 96% of fish species. The cladogram shows

760-427: A hard skull , but lacking limbs with digits . Fish can be grouped into the more basal jawless fish and the more common jawed fish , the latter including all living cartilaginous and bony fish , as well as the extinct placoderms and acanthodians . Most fish are cold-blooded , their body temperature varying with the surrounding water, though some large active swimmers like white shark and tuna can hold

836-648: A higher core temperature . Many fish can communicate acoustically with each other, such as during courtship displays . The study of fish is known as ichthyology . The earliest fish appeared during the Cambrian as small filter feeders ; they continued to evolve through the Paleozoic , diversifying into many forms. The earliest fish with dedicated respiratory gills and paired fins , the ostracoderms , had heavy bony plates that served as protective exoskeletons against invertebrate predators . The first fish with jaws ,

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912-436: A more spherical lens . Their retinas generally have both rods and cones (for scotopic and photopic vision ); many species have colour vision , often with three types of cone. Teleosts can see polarized light ; some such as cyprinids have a fourth type of cone that detects ultraviolet . Amongst jawless fish , the lamprey has well-developed eyes, while the hagfish has only primitive eyespots. Hearing too

988-422: A native ecological system disturbed by economic development or other events, they may be historically inaccurate, incomplete, or pay little or no attention to ecotype accuracy or type conversions. They may fail to restore the original ecological system by overlooking the basics of remediation. Attention paid to the historical distribution of native species is a crucial first step to ensure the ecological integrity of

1064-419: A protective bony cover or operculum . They are able to oxygenate their gills using muscles in the head. Some 400 species of fish in 50 families can breathe air, enabling them to live in oxygen-poor water or to emerge on to land. The ability of fish to do this is potentially limited by their single-loop circulation, as oxygenated blood from their air-breathing organ will mix with deoxygenated blood returning to

1140-523: A quantum radical pair mechanism . Indigenous (ecology) The notion of nativity is often a blurred concept, as it is a function of both time and political boundaries. Over long periods of time, local conditions and migratory patterns are constantly changing as tectonic plates move, join, and split. Natural climate change (which is much slower than human-caused climate change ) changes sea level, ice cover, temperature, and rainfall, driving direct changes in habitability and indirect changes through

1216-532: A rapid growth spurt during this phase, reaching its market weight of 1–2.5 kg (2–6 lb) within a year. They are fed dried pellets consisting mainly of fish meal and fish oil from forage fish that are too small and bony for human consumption. Carotenoids are also added, giving Arctic char its characteristic coral colouration. The land-based Arctic char farming systems are among the most environmentally responsible fish farming designs. They remove particulate matter and effluent prior to releasing water from

1292-574: A role in human culture through the ages, serving as deities , religious symbols, and as the subjects of art, books and movies. The word fish is inherited from Proto-Germanic , and is related to German Fisch , the Latin piscis and Old Irish īasc , though the exact root is unknown; some authorities reconstruct a Proto-Indo-European root * peysk- , attested only in Italic , Celtic , and Germanic . About 530 million years ago during

1368-441: A sense of touch and of hearing . Blind cave fish navigate almost entirely through the sensations from their lateral line system. Some fish, such as catfish and sharks, have the ampullae of Lorenzini , electroreceptors that detect weak electric currents on the order of millivolt. Vision is an important sensory system in fish. Fish eyes are similar to those of terrestrial vertebrates like birds and mammals, but have

1444-485: A tail fin, jaws, skin covered with scales , and lays eggs. Each criterion has exceptions, creating a wide diversity in body shape and way of life. For example, some fast-swimming fish are warm-blooded, while some slow-swimming fish have abandoned streamlining in favour of other body shapes. Fish species are roughly divided equally between freshwater and marine (oceanic) ecosystems; there are some 15,200 freshwater species and around 14,800 marine species. Coral reefs in

1520-585: A true "land fish" as this worm-like catfish strictly lives among waterlogged leaf litter . Cavefish of multiple families live in underground lakes , underground rivers or aquifers . Like other animals, fish suffer from parasitism . Some species use cleaner fish to remove external parasites. The best known of these are the bluestreak cleaner wrasses of coral reefs in the Indian and Pacific oceans. These small fish maintain cleaning stations where other fish congregate and perform specific movements to attract

1596-422: A typical fish is adapted for efficient swimming by alternately contracting paired sets of muscles on either side of the backbone. These contractions form S-shaped curves that move down the body. As each curve reaches the tail fin, force is applied to the water, moving the fish forward. The other fins act as control surfaces like an aircraft's flaps, enabling the fish to steer in any direction. Since body tissue

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1672-565: Is also found in Lake Pingualuit in the Ungava Peninsula , Quebec , a lake situated in an impact crater formed roughly 1.4 million years ago. Since the last glaciation , changing water levels are believed to have connected the lake with glacial runoff and surrounding streams and rivers, allowing char to swim upstream into the lake. Arctic char is the only fish found in the lake, and signs of fish cannibalism have been found. Arctic char

1748-465: Is an important sensory system in fish. Fish sense sound using their lateral lines and otoliths in their ears, inside their heads. Some can detect sound through the swim bladder. Some fish, including salmon, are capable of magnetoreception ; when the axis of a magnetic field is changed around a circular tank of young fish, they reorient themselves in line with the field. The mechanism of fish magnetoreception remains unknown; experiments in birds imply

1824-507: Is at risk there from acidification. In other parts of its range, such as the Nordic countries , it is much more common, and is fished extensively. In Siberia , it is known as golets ( Russian : голец ) and it has been introduced in lakes where it sometimes threatens less hardy endemic species, such as the small-mouth char and the long-finned char in Elgygytgyn Lake . The Arctic char

1900-462: Is closely related to both salmon and lake trout , and has many characteristics of both. The fish is highly variable in colour, depending on the time of year and the environmental conditions of the lake where it lives. The appearance of Arctic char differs between populations. The dorsal side of the Arctic char is dark in its colour while the ventral varies from red, yellow, and white. Arctic char has

1976-431: Is denser than water, fish must compensate for the difference or they will sink. Many bony fish have an internal organ called a swim bladder that allows them to adjust their buoyancy by increasing or decreasing the amount of gas it contains. The scales of fish provide protection from predators at the cost of adding stiffness and weight. Fish scales are often highly reflective; this silvering provides camouflage in

2052-568: Is found as far north; it is, for instance, the only fish species in Lake Hazen which extend up to 81°56′N 68°55′W  /  81.933°N 68.917°W  / 81.933; -68.917  ( Lake Hazen (northeast) ) on Ellesmere Island in the Canadian Arctic . It is one of the rarest fish species in Great Britain and Ireland , found mainly in deep, cold, glacial lakes , and

2128-466: Is known as iqaluk or tariungmiutaq in Inuktitut . Generally, whole market-sized fish are between 1 and 2.5 kg (2 lb 3 oz and 5 lb 8 oz). Male and female Arctic char are the same size. The flesh colour can range from a bright red to a pale pink. The Arctic char was initially scientifically described in the salmon genus Salmo as Salmo alpinus by Carl Linnaeus in

2204-695: Is notable for exhibiting numerous, seemingly distinct morphological variants or ' morphs ' throughout the range of the species. Consequently, Arctic char have been referred to as the "most variable vertebrate on Earth". These morphs are often sympatric within lakes or rivers. Morphs often vary significantly in size, shape, and colour. Morphs often demonstrate differences in migratory behaviour, being resident or anadromous fish, and in feeding behaviour and niche placement. Morphs often interbreed, but they can also be reproductively isolated and represent genetically distinct populations, which have been cited as examples of incipient speciation . In Iceland , Þingvallavatn

2280-417: Is noted for the evolution of four morphs: small benthic , large benthic, small limnetic and large limnetic. In Svalbard , Norway , Lake Linnévatn on Spitsbergen has dwarf, 'normal', and normal-sized anadromous fish, and Lake Ellasjøen on Bear Island has a dwarf, small littoral and large pelagic morph. In 2004, a previously unknown species closely related to Arctic char were discovered swimming near

2356-465: Is the biggest part of the brain; it is small in hagfish and lampreys , but very large in mormyrids , processing their electrical sense . The brain stem or myelencephalon controls some muscles and body organs, and governs respiration and osmoregulation . The lateral line system is a network of sensors in the skin which detects gentle currents and vibrations, and senses the motion of nearby fish, whether predators or prey. This can be considered both

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2432-439: Is thought to derive from Old Irish ceara / cera meaning "[blood] red", referring to its pink-red underside. This would also connect with its Welsh name torgoch , "red belly". In North America , three subspecies of Salvelinus alpinus have been recognized. " S. a. erythrinus " is native to almost all of Canada 's northern coast. This subspecies is nearly always anadromous . S. a. oquassa , known as

2508-520: Is thus a key species throughout many lakes in its range. Arctic char often demonstrates crypsis when defending from their predators. It will appear darker in its freshwater environments and lighter in its marine environments. Additionally, some juveniles have highly sensitive recognition of predator odours and respond to chemical cues from different fish predators. The diet of Arctic char varies with season and location. Arctic chars are generally opportunists . There have been more than 30 species found in

2584-462: The 1758 edition of Systema Naturae , which is the work that established the system of binomial nomenclature for animals. Meanwhile, he described Salmo salvelinus and Salmo umbla , which were later considered as synonyms of S. alpinus . John Richardson (1836) separated them into a subgenus Salmo ( Salvelinus ) , which now is treated as a full genus . The genus name Salvelinus is from German Saibling – little salmon. The English name

2660-531: The Cambrian explosion , fishlike animals with a notochord and eyes at the front of the body, such as Haikouichthys , appear in the fossil record . During the late Cambrian , other jawless forms such as conodonts appear. Jawed vertebrates appear in the Silurian , with giant armoured placoderms such as Dunkleosteus . Jawed fish, too, appeared during the Silurian: the cartilaginous Chondrichthyes and

2736-709: The Indo-Pacific constitute the center of diversity for marine fishes, whereas continental freshwater fishes are most diverse in large river basins of tropical rainforests , especially the Amazon , Congo , and Mekong basins. More than 5,600 fish species inhabit Neotropical freshwaters alone, such that Neotropical fishes represent about 10% of all vertebrate species on the Earth. Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams (e.g., char and gudgeon ) to

2812-514: The Inuit and in the subsistence economy of many circumpolar people . The fisheries are concentrated near communities and are predominately conducted using gill nets . In 2004, it was estimated that the subsistence harvest in the Cambridge Bay area was about 50% the size of the commercial harvest. Research aimed at determining the suitability of Arctic char as a cultured species has been going on since

2888-563: The Piteälven and Skellefteälven Rivers in the northern part of the country, though are believed to be relatively uncommon. There has been no formal naming of the hybrid between Arctic char and lake trout as few studies have been done in regard to this hybridization. Arctic char can be anadromous, landlocked, or semi-anadromous. Arctic chars found north of 65°N latitude are generally anadromous. Anadromous Arctic chars spend their juvenile years in fresh water, and once mature, migrate annually to

2964-562: The Society for Ecological Restoration , native plant societies, Wild Ones , and Lady Bird Johnson Wildflower Center encourage the use of native plants. The identification of local remnant natural areas provides a basis for this work. Many books have been written on the subject of planting native plants in home gardens. The use of cultivars derived from native species is a widely disputed practice among native plant advocates. When ecological restoration projects are undertaken to restore

3040-469: The abyssal and even hadal depths of the deepest oceans (e.g., cusk-eels and snailfish ), although none have been found in the deepest 25% of the ocean. The deepest living fish in the ocean so far found is a cusk-eel, Abyssobrotula galatheae , recorded at the bottom of the Puerto Rico Trench at 8,370 m (27,460 ft). In terms of temperature, Jonah's icefish live in cold waters of

3116-517: The blueback trout or Sunapee trout, is native to eastern Quebec and northern New England , although it has been extirpated from most of its northeastern United States range. S. a. oquassa is never anadromous. Dwarf Arctic char has been classified as S. a. taranetzi . These scientific names are not generally accepted, however, as the names S. a. erythrinus and S. a. taranetzi usually refer to subspecies that are endemic to Siberia only. Arctic char

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3192-1206: The evolutionary relationships of all groups of living fishes (with their respective diversity ) and the tetrapods. Extinct groups are marked with a dagger (†); groups of uncertain placement are labelled with a question mark (?) and dashed lines (- - - - -). Jawless fishes (118 species: hagfish , lampreys ) [REDACTED] † Thelodonti , † Conodonta , † Anaspida [REDACTED] [REDACTED] [REDACTED] † Galeaspida [REDACTED] † Osteostraci [REDACTED] † Placodermi [REDACTED] † Acanthodii [REDACTED]  (>1,100 species: sharks , rays , chimaeras ) [REDACTED]  (2 species: coelacanths ) [REDACTED] Dipnoi (6 species: lungfish ) [REDACTED] Tetrapoda (>38,000 species, not considered fish: amphibians, reptiles, birds, mammals) [REDACTED]  (14 species: bichirs , reedfish ) [REDACTED]  (27 species: sturgeons , paddlefish ) [REDACTED] Ginglymodi (7 species: gars , alligator gars ) [REDACTED] Halecomorphi (2 species: bowfin , eyetail bowfin ) [REDACTED]  (>32,000 species) [REDACTED] Fishes (without tetrapods) are

3268-400: The intertidal zone , are facultative air breathers, able to breathe air when out of water, as may occur daily at low tide , and to use their gills when in water. Some coastal fish like rockskippers and mudskippers choose to leave the water to feed in habitats temporarily exposed to the air. Some catfish absorb air through their digestive tracts. The digestive system consists of a tube,

3344-425: The stout infantfish . Swimming performance varies from fish such as tuna, salmon , and jacks that can cover 10–20 body-lengths per second to species such as eels and rays that swim no more than 0.5 body-lengths per second. A typical fish is cold-blooded , has a streamlined body for rapid swimming, extracts oxygen from water using gills, has two sets of paired fins, one or two dorsal fins, an anal fin and

3420-626: The Canadian Arctic, Greenland , Iceland, Scandinavia , Siberia, and Alaska . Anadromous Arctic chars migrate to the sea annually in mid-June to mid-July. After about two months, they return to fresh water to reproduce and overwinter . The main predators of Arctic char include sea otters ( Enhyrda lutris ), polar bears ( Ursus maritimus ), humans ( Homo sapiens ), ferox trout ( Salmo ferox ), and other fish species. Dwarf Arctic char are also often cannibalistically consumed by giant Arctic char. As ferox trout are an apex predator , Arctic char

3496-594: The Southern Ocean, including under the Filchner–Ronne Ice Shelf at a latitude of 79°S, while desert pupfish live in desert springs, streams, and marshes, sometimes highly saline, with water temperatures as high as 36 C. A few fish live mostly on land or lay their eggs on land near water. Mudskippers feed and interact with one another on mudflats and go underwater to hide in their burrows. A single undescribed species of Phreatobius has been called

3572-556: The attention of the cleaners. Cleaning behaviors have been observed in a number of fish groups, including an interesting case between two cichlids of the same genus, Etroplus maculatus , the cleaner, and the much larger E. suratensis . Fish occupy many trophic levels in freshwater and marine food webs . Fish at the higher levels are predatory , and a substantial part of their prey consists of other fish. In addition, mammals such as dolphins and seals feed on fish, alongside birds such as gannets and cormorants . The body of

3648-550: The body, and produce a concentrated urine. The reverse happens in freshwater fish : they tend to gain water osmotically, and produce a dilute urine. Some fish have kidneys able to operate in both freshwater and saltwater. Fish have small brains relative to body size compared with other vertebrates, typically one-fifteenth the brain mass of a similarly sized bird or mammal. However, some fish have relatively large brains, notably mormyrids and sharks , which have brains about as large for their body weight as birds and marsupials . At

3724-716: The bony Osteichthyes . During the Devonian , fish diversity greatly increased, including among the placoderms, lobe-finned fishes, and early sharks, earning the Devonian the epithet "the age of fishes". Fishes are a paraphyletic group, since any clade containing all fish, such as the Gnathostomata or (for bony fish) Osteichthyes , also contains the clade of tetrapods (four-limbed vertebrates, mostly terrestrial), which are usually not considered fish. Some tetrapods, such as cetaceans and ichthyosaurs , have secondarily acquired

3800-563: The bottom of Lake Tinn in Norway at a depth of 430 m (1,410 ft); The light-colored, translucent fish is up to 15 cm (5.9 in) long and lacks a swim bladder . In Sweden three morphs are usually recognised: storröding , större fjällröding and mindre fjällröding . Wherever these types occur together in the same lake storröding is the largest. Contrary to what the name may suggest when större fjällröding and mindre fjällröding are found together mindre fjällröding tend to be

3876-505: The bottom of the gravel till they are 15–18 cm (6–7 in) in length. Growth rates of Arctic char vary greatly. Numerous commercial fisheries take place in various river systems throughout the Canadian Arctic , with the majority in Nunavut , such as the areas of Cumberland Sound and Cambridge Bay . There are also exploratory fisheries to examine potential for future commercial char fishing areas. Arctic char fisheries are important for

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3952-534: The cold water temperatures present in numerous areas of Canada. It could be an alternate species to rainbow trout ( Oncorhynchus mykiss) , and could provide producers with a different niche in the marketplace. The initial research efforts concentrated on identifying the cultural needs and performance characteristics of the species. The Freshwater Institute was responsible for distributing small numbers of eggs to producers in Canada; these producers in return helped determine

4028-511: The fish tanks into the environment. Sludge removed from the water is used to fertilize terrestrial crops. Leftovers from fish processing may be incorporated into dog food or delivered to local compost facilities. In 2006, Monterey Bay Aquarium Seafood Watch program added farmed Arctic char as an environmentally sustainable Best Choice for consumers, stating: "Arctic char use only a moderate amount of marine resources for feed" and that they "are farmed in land-based, closed systems that minimize

4104-405: The front of the brain are the olfactory lobes , a pair of structures that receive and process signals from the nostrils via the two olfactory nerves . Fish that hunt primarily by smell, such as hagfish and sharks, have very large olfactory lobes. Behind these is the telencephalon , which in fish deals mostly with olfaction. Together these structures form the forebrain. Connecting the forebrain to

4180-412: The gills flows in the opposite direction to the water, resulting in efficient countercurrent exchange . The gills push the oxygen-poor water out through openings in the sides of the pharynx. Cartilaginous fish have multiple gill openings: sharks usually have five, sometimes six or seven pairs; they often have to swim to oxygenate their gills. Bony fish have a single gill opening on each side, hidden beneath

4256-532: The gills. Oxygen-rich blood then flows without further pumping, unlike in mammals, to the body tissues. Finally, oxygen-depleted blood returns to the heart. Fish exchange gases using gills on either side of the pharynx . Gills consist of comblike structures called filaments. Each filament contains a capillary network that provides a large surface area for exchanging oxygen and carbon dioxide . Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. Capillary blood in

4332-699: The globe at an unprecedented rate. Those working to address invasive species view this as an increased risk to native species. As humans introduce species to new locations for cultivation, or transport them by accident, some of them may become invasive species, damaging native communities. Invasive species can have profound effects on ecosystems by changing ecosystem structure, function, species abundance , and community composition. Besides ecological damage, these species can also damage agriculture, infrastructure, and cultural assets. Government agencies and environmental groups are directing increasing resources to addressing these species. Native plant organizations such as

4408-496: The gravel in spring and stay in the river from 5 to 7 months, or until they are about 15–20 cm (6–8 in) in length. Sexual maturity in Arctic char ranges from 4 to 10 years old and 50–60 cm (20–24 in) in length. Time to hatching varies, but usually occurs between two and three months, with the longest have been observed at five months. Arctic char ranges between 40 and 70 mg upon hatching. Hatchlings are immediately independent of parents at hatching, and stay at

4484-447: The gut, leading from the mouth to the anus. The mouth of most fishes contains teeth to grip prey, bite off or scrape plant material, or crush the food. An esophagus carries food to the stomach where it may be stored and partially digested. A sphincter, the pylorus, releases food to the intestine at intervals. Many fish have finger-shaped pouches, pyloric caeca , around the pylorus, of doubtful function. The pancreas secretes enzymes into

4560-452: The heart from the rest of the body. Lungfish, bichirs, ropefish, bowfins, snakefish, and the African knifefish have evolved to reduce such mixing, and to reduce oxygen loss from the gills to oxygen-poor water. Bichirs and lungfish have tetrapod-like paired lungs, requiring them to surface to gulp air, and making them obligate air breathers. Many other fish, including inhabitants of rock pools and

4636-455: The intestine to digest the food; other enzymes are secreted directly by the intestine itself. The liver produces bile which helps to break up fat into an emulsion which can be absorbed in the intestine. Most fish release their nitrogenous wastes as ammonia . This may be excreted through the gills or filtered by the kidneys . Salt is excreted by the rectal gland. Saltwater fish tend to lose water by osmosis ; their kidneys return water to

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4712-785: The largest morph. Even within storröding morphs can be found; for example the Sommen charr of Lake Sommen tend to grow faster and reach sexual maturity later than the char from Lake Vättern . Arctic char is known to produce hybrids with its congeners , Salvelinus namaycush (lake trout) and Salvelinus fontinalis (brook trout). The sparctic char is the intrageneric hybrid between Arctic char and brook trout. Sparctic char grows faster than either parent species, are stronger and healthier, and are thus popular for sports fisheries. Some of these hybrids are fertile while others are sterile. Sparctic char have been found locally in Sweden, for example in

4788-583: The late 1970s. The Canadian government's Freshwater Institute of Fisheries and Oceans Canada at Winnipeg , Manitoba, and the Huntsman Marine Science Centre of New Brunswick , pioneered the early efforts in Canada. Arctic char is also farmed in Iceland, Estonia , Norway , Sweden, Finland , West Virginia , and Ireland. Arctic char was first investigated because they expected it to have low optimum temperature requirements and would grow well at

4864-452: The marine environment. The first migration of Arctic char has been found to occur between 4 and 13 years of age. When in the marine environment, Arctic chars inhabit coastal and intertidal areas. They migrate back to frozen lakes at the end of summer. Generally, Arctic char inhabits shallow waters, rarely swimming deeper than 3 m (10 ft) depth. An exception to this applies to landlocked Arctic chars, which often swim much deeper in

4940-419: The midbrain is the diencephalon ; it works with hormones and homeostasis . The pineal body is just above the diencephalon; it detects light, maintains circadian rhythms, and controls color changes. The midbrain contains the two optic lobes . These are very large in species that hunt by sight, such as rainbow trout and cichlids . The hindbrain controls swimming and balance.The single-lobed cerebellum

5016-443: The nine largest families; from largest to smallest, these are Cyprinidae , Gobiidae , Cichlidae , Characidae , Loricariidae , Balitoridae , Serranidae , Labridae , and Scorpaenidae . About 64 families are monotypic , containing only one species. Fish range in size from the huge 16-metre (52 ft) whale shark to some tiny teleosts only 8-millimetre (0.3 in) long, such as the cyprinid Paedocypris progenetica and

5092-424: The one under consideration. The terms endemic and native also do not imply that an organism necessarily first originated or evolved where it is currently found. Native species form communities and biological interactions with other specific flora, fauna, fungi, and other organisms. For example, some plant species can only reproduce with a continued mutualistic interaction with a certain animal pollinator , and

5168-402: The open ocean. Because the water all around is the same colour, reflecting an image of the water offers near-invisibility. Fish have a closed-loop circulatory system . The heart pumps the blood in a single loop throughout the body; for comparison, the mammal heart has two loops, one for the lungs to pick up oxygen, one for the body to deliver the oxygen. In fish, the heart pumps blood through

5244-469: The placoderms, appeared in the Silurian and greatly diversified during the Devonian , the "Age of Fishes". Bony fish, distinguished by the presence of swim bladders and later ossified endoskeletons , emerged as the dominant group of fish after the end-Devonian extinction wiped out the apex predators , the placoderms. Bony fish are further divided into the lobe-finned and ray-finned fish . About 96% of all living fish species today are teleosts ,

5320-670: The pollinating animal may also be dependent on that plant species for a food source. Many species have adapted to very limited, unusual, or harsh conditions, such as cold climates or frequent wildfires . Others can live in diverse areas or adapt well to different surroundings. The diversity of species across many parts of the world exists only because bioregions are separated by barriers, particularly large rivers , seas , oceans , mountains , and deserts . Humans can introduce species that have never met in their evolutionary history, on varying time scales ranging from days to decades (Long, 1981; Vermeij, 1991). Humans are moving species across

5396-405: The presence of predators, competitors, food sources, and even oxygen levels . Species do naturally appear, reproduce, and endure, or become extinct, and their distribution is rarely static or confined to a particular geographic location. Moreover, the distinction between native and non-native as being tied to a local occurrence during historical times has been criticised as lacking perspective, and

5472-698: The project. For example, to prevent erosion of the recontoured sand dunes at the western edge of the Los Angeles International Airport in 1975, landscapers stabilized the backdunes with a "natural" seed mix (Mattoni 1989a). Unfortunately, the seed mix was representative of coastal sage scrub , an exogenous plant community, instead of the native dune scrub community. As a result, the El Segundo blue butterfly (Euphilotes battoides allyni) became an endangered species. The El Segundo blue butterfly population, which had once extended over 3200 acres along

5548-409: The risk of escape into the wild." Commercial Arctic char typically weigh 1–2.5 kg (2–6 lb). The flesh is fine-flaked and medium firm. The colour is between light pink and deep red, and the taste is like something between trout and salmon . Fish A fish ( pl. : fish or fishes ) is an aquatic , anamniotic , gill -bearing vertebrate animal with swimming fins and

5624-454: The stomachs of Arctic chars. During late spring and summer, Arctic char feeds on insects found on the water's surface, salmon eggs, snails and other smaller crustaceans found on the lake bottom, and smaller fish up to a third of its size. During the autumn and winter months, it feeds on zooplankton and freshwater shrimps that are suspended in the lake, and also occasionally on smaller fish. The marine diet of Arctic char consists mostly of

5700-419: The suitability of Arctic char in a commercial setting. Commercial Arctic char breeding stocks have now been developed largely from these sources. Arctic char eggs are hatched within specialized hatchery facilities. The young fish remain in the hatchery until they reach about 100 g ( 3 + 1 ⁄ 2  oz), and are then transferred to tanks each capable of holding 5000 fish. Arctic char first exhibits

5776-414: The summer in order to occupy colder waters. Dwarf Arctic chars are more common in landlocked populations as a result of scarce resources (immense competition ). Arctic char exhibits a mostly circumpolar distribution . There is no other species of freshwater fish found at a higher latitude. Arctic char is native to Arctic and subarctic coasts and lakes of high elevations. In general, it has been observed in

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