Thymallus arcticus baicalensis (Dybowski, 1874)
The family Thymallidae of Lake Baikal is represented by a Baikal subspecies of Siberian grayling, which has two forms – black and white grayling. Black grayling has anal and dorsal fins especially high in its back part. It has 16-22 gill rakers. It may be 60 cm long with a weight of 1.5 kg. Fins and the body are of bright colour especially during its spawning period. Scales are dense. There is little lipopexis in the body. The grayling inhabits mainly shallow areas with stony soils. It spawns in spring in almost all the tributaries of Lake Baikal and in the Angara River. It feeds mainly on larvae and adults of caddies-flies, stone flies, Gammarus, and roes of sculpins during their spawning. The grayling is a very active fish. Going upstream to the spawning grounds, the grayling can get over the disturbed turbulent flow of the river and even its rapids. While hunting flying insects, it can jump out of the water at the height of 0.5 m.
Black grayling of Lake Baikal
White grayling of Lake Baikal
The black grayling inhabits the rivers entering Lake Baikal, as well as its coast and bays. It is spread mainly in the southern and northern parts of the lake, at the sites with stony-pebble bottom. In summer, the grayling occurs at a depth of 10-20 m. In autumn, the grayling migrates to the shores for wintering, where it is concentrated at a depth of 3-12 m. Spawning migrations of the grayling to the places of its reproduction are observed in late March, when the water temperature in the rivers is 1-3ºC. The optimal temperature at which spawning starts is 4-8.5ºC. The grayling chooses rivers, streams with stony and pebble soils and swift currents for spawning. The grayling becomes mature with the body length of 25-30 cm and weight of 250-400 g.
The white grayling has a higher body, pectoral and abdominal fins are short, and dorsal fin is low. The caudal peduncle is longer and low. It has 14-20 gill rakers. The main colour of the body is gray. There is more lipopexis in the body cavity. Therefore, the meat is of lighter colour and softer. Scales are less dense. The white grayling is larger than the black one. It grows faster reaching the weight of 3.0-3.5 kg. The grayling inhabits the coastal zone of Lake Baikal up to the depth of 50 m. It feeds upon benthic organisms. Sometimes the grayling can feed upon plankton or insects. It spawns in Lake Baikal.