Dolly Varden char (Salvelinus malma)
This is the most widespread and numerous char in the world, and one of the most numerous salmonid fish of the North Pacific. The natural range of Dolly Varden is huge; it covers both Asian and American Pacific coasts from about 45°N to the Bering Strait, and also the coast of the Polar Sea from the Kolyma River in Asia to the Mackenzie River in North America.
The biggest char specimens (up to 12 kg) enter rivers of the Arctic Ocean, but in the Pacific Ocean drainage even the 3-kg fish are rare. The most common forms of the species are anadromous and dwarf brook-resident. In the southern part of the range the typical “northern” Dolly Varden char (Salvelinus malma malma) are replaced by the “southern” subspecies (S. m. krasheninnikovi). Scientists do not agree yet if it is a subspecies or a distinctive, related species of char.
In many rivers, Dolly Varden are found together with other species of anadromous chars and in most cases it is not difficult to distinguish them. The silver sides of bright Dolly Varden specimens have numerous small red dots, over 40 dots per side; each dot is smaller than the fish’s eye pupil. The anadromous Arctic char, which coexists with Dolly Varden in Chukotka, has fewer and larger pink dots. These dots are much bigger than the eye pupil and could be even bigger than the size of the fish’s eye; some of these dots are cut by the lateral line.
The backs of bright silver Dolly Varden have a green tinge. Yellow-mouth char living in some rivers of the Sea of Okhotsk have a pale-yellow shade on their backs and sides, no red dots, and some other characteristic differences (see the species description). Only silver specimens of the anadromous white char from the Kamchatka River look quite similar to anadromous Dolly Varden char. On the other hand, the spawning colors of all char species are completely different and allow you to easily distinguish between them.
Parr of anadromous Dolly Varden are small dark gray (olive gray) fish no more than 20 cm long, with small white or red dots and dark parr marks, often also with a pink or yellow belly. This fish can spend from two to nine years in the river, but most often only three to four years. In June you can see among the parr bright silver 15–20-cm-long fish without any dots or marks on their sides. These are smolts ready to make their first sea migration. After becoming a smolt, Dolly Varden begins to make two annual migrations: in spring they go downstream into the sea, and in summer or fall they come back into the freshwater.
The growth of char parr in the river is about 2–2.5 cm a year or less, and after becoming smolts 5–8 cm a year. At the end of the first sea migration, Dolly Varden weigh 100–150 g. After wintering and the second sea migration the same fish is 28–35 cm long and weighs 300-500 g. After the third migration it is 35–40 cm and 650–900 g. At this size the Dolly Varden become mature and spawn for the first time.
The average life expectancy of migratory char in the Pacific basin is 8–9 years, while in the Arctic Ocean basin it is 1-2 years longer. The downstream migration of all age groups of the Dolly Varden into the sea coincides with the ice-flood and spring flood in the given basin. On the Arctic Ocean coast of Chukotka, the chars go into the sea in June, on the Sea of Okhotsk coast – in May, and on the Sea of Japan coast and the Kuril Islands – in April.
Lake populations of Dolly Varden are rare; as a rule, the lakes are inhabited by other char species with better adaptations for living in stagnant water. One of the known stocks of the lake-resident Dolly Varden is the population of the «mollusk-eating chars» from the Lake Azhabachye, Kamchatka.
In most regions of the Far East, the resident Dolly Varden char is found in small, fast streams and small rivers; it grows slowly and rarely reaches the length of more than 25 centimeters. In the Northern Primorye, the river resident Dolly Varden char is quite numerous. This fish is found in mountain rivers of significant size; it is much larger than the brook-resident chars – there are individuals weighing more than one kilogram.
Similar to other anadromous salmonids with long freshwater periods, Dolly Varden and other chars have strong homing instincts. Because of this, char stocks must be managed separately in every river basin. In the Far East, Dolly Varden now have the status of a sportfish, protected with a bag limit. This fish still remains an object of commercial fisheries in rivers for local use. As a result, in all rivers with easy access, the size and number of chars are decreasing. To become mature, Dolly Varden has to make three sea migrations. This means that the fish have to pass the lower part of a river with strong fishing pressure six times and thus their chances of being caught are significant. As a result of this vulnerability, the fishing restrictions for the Dolly Varden char must be stronger.