Arctic Charr: Noble fish for demanding markets

Arctic CharrArctic charr (Salvelinus alpinus), also called mountain trout or salmon trout, is a member of the salmon family (Salmonidae). It is a coldwater species that occurs in Arctic, sub-Arctic and Alpine waters as well as in northern coastal waters. Like salmon, Arctic charr enters the upper reaches of rivers to breed. Some populations inhabit freshwater permanently, others migrate to the sea and only return to the rivers for reproduction.

That Arctic charr is closely related to salmon and trout can already be seen from the fish’s external appearance – its salmon-like body with the adipose fin. The fish’s behaviour is also similar to that of its sister species, for example with regard to its migratory instinct which can be observed in several populations, or its spawning behaviour. Like salmon, Arctic charr reproduces during the winter months and usually spawns on a gravelly bed. However, what distinguishes the Arctic charr from its relatives is the variability in colouring and the wide and fragmented distribution area which was influenced by glacial epochs. The fish’s colouring varies depending on the water in which it lives, its gender, and its maturity. The migratory fish mostly has a steel blue back, the inland fish is usually greenish brown. On their belly side the fishes are yellowish to reddish grey but this colour changes during spawning time to a brilliant orange-red colour. Even the colour of the meat is variable – in some cases it is dark red, in others only a pale shade of pink.

No other freshwater species in Europe advances as far north as the Arctic charr. The anadromous charr from the European Siberian Arctic Ocean that still enters a lot of rivers there today is considered to be the basic form of this fish species. The distribution pattern of Arctic charr, comprising numerous populations that are isolated from each other, developed in northern Europe as a result of the ice age. In addition to the migratory Arctic charr, there are also an amazing number of landlocked Arctic charr that are mostly isolated in their reproduction. Even specialists have to go to considerable effort to identify them.

 

In Europe alone there are about 25 forms of Arctic charr. In the Italian Alps lives a Salvelinus type that is called Salmerino. In the Alpine lakes of the Rhine, Meurthe and Rhône regions two “races” of Omble chevalier are distinguished that differ in their growth and in their nutrition. There is a comparable split in the fishes that live in Alpine lakes in the river region of the upper Danube. In addition to the extremely colourful “normal” Arctic charrs which are mainly predatory fishes that grow to over 50 cm there is an unobtrusive dwarf form that mainly eats plankton and rarely grows to more than 20 cm in length. It is possible that the two Arctic charr types only represent adaptations to different ecological niches within their habitat, but it is also possible that two new, independent species are developing differently here. Recent genetic testing would seem to imply the latter. And as if the situation were not confusing enough already there are also numerous sub-species and hybrid forms of Arctic charr, since a lot of charr species reproduce among each other. The so-called Alsace char which is produced frequently in aquaculture is for example a cross between Arctic charr and brook charr/ brook trout.

The migratory form of Arctic charr is mainly to be found in the Arctic waters of the Atlantic and Pacific Oceans; the distribution area of Arctic charr in Europe extends from the coasts of Iceland as far as the Oslo fjord. Landlocked freshwater forms live in clear, cold, oxygen-rich lakes in Siberia, Scandinavia, Iceland, Ireland and Great Britain, in the Pyrenees, the Alpine region and in the foothills of the Alps up to a height of 2,600 m. Arctic charr is often the only fish species in these waters. If the population grows too strongly the large fishes can become cannibalistic and eat their own young.

 

Tolerance for limited range of temperatures and relatively slow growth

The migratory or normal form of Arctic charr grows to a length of about 40 to 60 cm and reaches a weight of one to two kilograms (the record is said to be 1 m and 14 kg). The dwarf race of the landlocked form usually remains much smaller reaching a length of only 15 cm and a weight of about 100 gram.

The migratory Arctic charr’s way of life is similar to that of the salmon. After the fishes have spent their youth in freshwater they migrate to the sea where they continue to grow and, when they become mature, swim to the upper reaches of the rivers again to spawn. Because the Arctic charr grows more slowly than the salmon the individual life phases are accordingly longer. Whilst young salmon, for example, often leave the rivers to swim to the sea already after two years, young Arctic charr remain in freshwater for three to four years. During this time they mainly feed on small animals, particularly worms, insect larvae and other invertebrates. Later on in the sea they will become predators, however, and will mainly feed on fishes, mostly smaller species, for example sandeels, sandsmelt, and smelt but also young cod. The fishes reach maturity at an age of 6 to 7 years. They then return to the rivers in early autumn and spawn during the winter months. Like salmon, Arctic charr lays its eggs in hollows which the female makes in the gravelly bed with her tail fin. Because the males mainly stay close to the nests it is presumed that they are protecting their spawning grounds from intruders and egg predators and thus taking care of their young. Depending on their size, female Arctic charr lay between 2,500 and 8,500 eggs which are about 4 to 4.5 mm in size. It takes about three months until the larvae hatch, mostly at the start of spring. When they have eaten up the contents of the yolk sac they feed on insect larvae, planktonic crustaceans and amphipoda. As in all salmonid species the young of Arctic charr are recognizable from the characteristic vertical, dark-coloured stripes that are a typical feature of parr (fish over one year old).

The reproduction behaviour of the landlocked forms can be of two different types, a distinction being made between the fishes that spawn near the lake banks and those that spawn on the bed. The former lay their eggs between September and January in shallow bank regions of 4 to 10 metres depth. In contrast, the bottom spawners reproduce in summer from July to August on stony beds at depths of 20 to 80 metres. These fishes prefer places where fresh water swells up out of the deep.

What makes Arctic char interesting for most consumers is, however, neither its biology nor the intricate relationships within the species, but its excellent culinary qualities. The meat of the fish is of medium firmness and has a fine structure. Fillet colour can vary between pale pink and dark red depending on the fish’s origin and diet. Its flavour is somewhere between salmon and trout. Some gourmets even claim that it has the most noble and best meat of all the salmonids. And like salmon, the fillet of Arctic charr contains lots of polyunsaturated fatty acids – Omega 3 fatty acids – which are said to have numerous positive attributes for the heart, brain, and blood circulation. The fact that demand for this first-class fish is rather seldom probably has a lot to do with its still being largely unknown to many consumers. It is also not readily available at the retailer’s and is relatively expensive. According to FAO statistics the worldwide Arctic charr catch from fisheries was always below 200 t in recent years. Although the actual quantity is probably higher because Arctic charr is also very popular among sport fishermen this is not likely to change much in the low availability of the fish on the market.

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Arctic charr thrives in water at 5-6°C and wild populations are therefore found mainly in northern countries. In Europe, Iceland is the biggest producer of farmed Arctic charr.

 

Aquaculture contributes substantially to market availability

The fact that Arctic charr is at least occasionally to be found at the fishmonger’s is mainly thanks to aquaculture. Like salmon and trout this salmonid species is quite suitable for production in aquaculture. One prerequisite, however, is that the water temperatures do not rise too much over the course of the year. For that reason Arctic charr farms are mainly to be found in northern countries or mountain regions at high altitudes where such temperatures prevail throughout the year. Often Arctic charr is a substitute for trout which prefer slightly higher temperatures. According to the FAO, 3,719 t Arctic charr were produced worldwide in aquaculture in 2011: Iceland contributed 3,027 t, Norway 276 t and Canada 200 t, together about 95% of the total. The rest came from countries like Italy (140 t), Austria (40 t) and Ireland (40 t).

In Iceland, the most important aquaculture country for Arctic charr, several pioneers were already investigating farming possibilities for this fish over one hundred years ago. Shortly after 1900 they succeeded in hatching eggs and producing broodstock for farming purposes. When in the 1960s a viable feed was developed the first farms were opened, if only at a modest level. Iceland’s Arctic charr sector then experienced a boom in the 1980s and 1990s when the number of farms rose to about 40. A lot of them unfortunately did not prove to be profitable and the farmers soon gave up again. Today there are less farms in Iceland (probably currently nearly 15 in all) but these farms have much higher production capacities. A state farming programme that was initiated in 1992 contributed decisively to the success of Icelandic Arctic charr farming which rose continuously as from then. In the mid-1990s annual production amounted to about 500 t and in 2008 production for the first time exceeded the 3,000 t mark. Only between 2004 and 2006 was there a slight setback because individual hatcheries were hit by a bacterial kidney disease and were not permitted to supply young fishes to the grow-out farms.

In Iceland Arctic charr is mainly produced in landbased farms in specially designed ponds or basins that are completely separate from their surroundings. This means that any escapes from the farms cannot get into natural waters and endanger the wild population. In the event that a disease breaks out on the farm the pathogens remain isolated in the basin… particularly because the water that flows out of the basin is thoroughly processed and cleaned after use. Nearly all the big farms use ground water which is available in sufficient quantities in a lot of locations in Iceland. Although the water is slightly salty it is very good for Arctic charr farming because it is filtered by volcanic intrusive rock, it is crystal-clear and largely pathogen free. Apart from that, at a temperature of 5 to 6°C it is of an optimal temperature for the production of the cold-loving fish species. Occasionally spring water is also used but only by a few and usually smaller operations. Only one single company farms Arctic charr in floating net cages. This facility is in a bay on the northeast coast of the island, an isolated region with hardly any inhabitants. Depending on the temperature and other farming conditions the fishes need between 18 and 32 months to reach the desired marketable weight of between 300 grams and 2 kg.

In Iceland farm production of Arctic charr is based solely on artificially hatched fry. Modified light and temperature conditions enable the hatcheries to get the fishes to maturity and spawning outside of the regular spawning time, too, so that stocking material is available practically throughout the year. Mostly the young fishes remain in the hatcheries until they have reached a weight of 70 to 100g. The main producers of Arctic charr eggs in Iceland are Stofnfiskur and Holar University College that also runs regular farming programmes. They supply to a lot of Icelandic farming facilities in which the eggs are then hatched and the fry grown out in nurseries to a size suited to stocking. At present the production capacity of Icelandic Arctic charr aquaculture is probably already well over 3 million fry per year.

Samherji, with its companies Islandsbleikja, Islandslax and Silfurstjarnan, is a vertically integrated enterprise that unites all stages of the production chain from hatching and outgrowing to harvesting, packaging and marketing. It is the biggest Arctic charr producer in Iceland and thus naturally worldwide. Before the fry go into the farms they are given a vaccination which makes the use of antibiotics and other medication unnecessary during the farming process. More than half of the protein in the feed is of marine origin (fish meal), other animal meals are not used. Prior to harvesting, the fishes are given no more feed for at least 4 days to improve the flavour and texture of the meat. Arctic charr is marketed either whole (gutted, head on) or in the form of fully trimmed fillets, both fresh and frozen. mk