The Arctic char or Arctic charr (Salvelinus alpinus) is a cold-water fish in the family Salmonidae, native to alpine lakes and arctic and subarctic coastal waters. Its distribution is Circumpolar North. It spawns in freshwater and populations can be lacustrine, riverine, or anadromous, where they return from the ocean to their fresh water birth rivers to spawn.[3] No other freshwater fish 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 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 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 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 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 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).[9] Male and female Arctic char are the same size.
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 the marine environment. The first migration of Arctic char has been found to occur between four 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 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).
Range
Arctic char exhibits a Circumpolar North distribution. There is no other species of freshwater fish found at a higher latitude.[31][32][34][35] Arctic char is native to Arctic and subarctic coasts and lakes of high elevations. In general, it has been observed in 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.
Predation
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 chars are also often cannibalistically consumed by giant Arctic chars. As ferox trout are an apex predator, Arctic char 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.
Diet
The diet of Arctic char varies with season and location. Arctic chars are generally opportunists. There have been more 30 species found in 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 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.
Reproduction
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 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 chars do not die after spawning like Pacific salmon, and often spawn several times throughout their lives, typically every second or third year. Young Arctic chars emerge from 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.
