Arctic Char (Salvelinus alpinus)
Arctic Char (Salvelinus alpinus) are generally distinguished from other salmonid fishes by having light spots on a dark background and by the lack of teeth on the shaft of the vomer (upper palate of the mouth). Arctic char are highly variable in colour depending on environmental conditions within their lake of residence and time of year, but are generally brown to greenish-brown on their upper body and lighter on their lower body. They have sparse pink to red spots on their back and sides (15-20 below their lateral line) and typically, the leading edge of their lower fins are white. In spawning adults, especially males, the lower body and the lower fins are orange to red, with fins having a prominent white leading edge. Spawning colours are more exaggerated in males than in females.
Distribution and Habitat
The Arctic charr has a circumpolar distribution, stretching from Alaska to northern Russia, including Canada, Greenland, Norway and Iceland. There are isolated populations in the northern United Kingdom, Scandinavia and Finland, as well as landlocked populations in Canada and the United States.
Migratory behaviour in the Arctic charr is highly variable. Certain populations make annual migrations from the sea to a freshwater lake or river. Other populations are sedentary and remain within their freshwater habitat throughout their lives. Riverine populations have been known to perform migrations within the river system or may also be sedentary. The Arctic charr inhabits freshwater lakes and rivers, as well as estuaries and oceans, where there is cold, clear water. Populations in the ocean remain close to the coastline. In rivers, the Arctic charr are found in deep runs and pools.
Growth and Reproduction
Little is known about the life history of Arctic char in Alaska lakes. However, in other areas, char often exist in two different forms in the same lake. These forms are usually described as “dwarf’ and “normal.” The forms show differences in habitat and food selection, resulting in different growth rates, size at maturity, and average size. Growth is slow for Arctic char in Alaska’s cold, often nutrient-poor lakes. Some arctic char have been known to live for over 20 years.
Maximum size may vary greatly, depending on the productivity of the particular lake and the presence of other fish species. Fish over 10 pounds are not uncommon in some Alaska lakes, while other lakes may not produce fish over 2 pounds even though fish may reach great age. The largest Arctic char in Alaska probably occur in some of Bristol Bay’s large lakes, where good fishing can be had from late May through early July when these fish congregate to feed on salmon smolts as they move toward the sea.
Spawning takes place in lakes between the fall months of August and October. Most char are ready to spawn between six to nine years and individuals usually spawn only every other year. Eggs are fertilised and deposited over jumbles of substrate or shoals of gravel. Spawning sites are also chosen based on water depth; thick ice can freeze to the bottom in shallower portions of lakes.
In some lakes, pre-spawning char congregate near inlet streams or waterways connecting lakes, but they move back into the lake to spawn. Prior to spawning the female selects a location within the male’s territory and begins to dig the spawning nest or redd. The male courts the female by circling around her. He then moves alongside her and quivers. The mating pair ejects eggs and milt into the pit area and the fertilised eggs are deposited into the gravel. The fertilised eggs will hatch after 2 months, usually before the spring. Young arctic char begin to feed after emerging from the gravel.
Arctic char feed on a variety of different food items from zooplankton and insects to other fish (including smaller char) depending upon the specific water body, their age and relative size, as well as time of year.