Together with acclimatized ones there are 53 fish species and sub-species of 13 families in Lake Baikal. The Baikal ichthyofauna has been formed as a result of coming to the lake of the fish belonging to different fresh water fauna complexes and the indigenous (autochthonous) fauna evolution which was happening at different times. All the Baikal fishes belong to three ecological and fauna complexes: the Siberian one (14 species and sub-species), the Siberian-Baikal one (10 species and sub-species) and the Baikal one (29 species).
The Siberian complex is made up with the general Siberian species which inhabit the coastal-sor zone of the Baikal. They are mostly carps, perches and pikes. The acclimatized species such as the sazan, the sheat-fish and the bream are also included into this group. The Siberian-Baikal complex is represented by the graylings, sigs and sturgeons which live in the coastal slope (up to 300 m) zone of the lake and come to the pelagic part of the open Baikal in summer and in autumn.
The Baikal fish complex dominates in the lake, it makes up 56% of the general number of species and 80% of the whole fish production of the lake. The complex is represented by the bull-head fishes 27 species of which are endemics. These species live in the lake from the upper layer down to the maximum depth. The coastal bull-heads live together with representatives of other complexes and are, from the one hand, their food, on the other hand they are their food competitors. The bull-heads spawn mostly in spring and in summer. The females spawn under stones and then throughout the period of the development it is being guarded by the male that constantly drives fresh oxygen saturated water with its fines.
In the pelagic zone of the open Baikal 2 species of golomyanka fish live. They do not have the swimming bladder which makes their motion in the water thick difficult, that’s why they have a number of devices connected with pelagialization. They are great (up to 40% with the big golomyanka) content of fat, the skull bones thinness, the abdominal fins skeleton reduction and, vice versa, bigger thoracic, dorsal and anal fins. The golomyankas are viviparous, they do not spawn but cast up to 1-3 thousand young fish into the water. They are the most numerous kind of the Baikal fish. At the body weight of 15-25 g their general mass is about 160 thousand tons which is greater than all the other fishes mass taken together. But they have no economic meaning because they do not make big schools.
There are only 15 kinds of fish (out of 53) living in Lake Baikal which have economic meaning. They are the omul, the sig, the grayling, the lenok (?), the taymen (?), the sturgeon, the burbot, the perch, the pike, the roach, the yelets (?), the ide, the crucian, the yellow-finned and the long-finned bull-heads.
The main marketable fish of the Baikal is the omul which was described by Georgi in 1775. By the habitats and outward appearance there are 3 ecological and morphological groups of it: the pelagian omul (reproducing in the Selenga river and putting on weight in the upper waters of the Baikal), the coastal one (spawning in the rivers of the northern end of the lake and feeding in the coastal zone) and the ground deep water one spawning in the small rivers. Thanks to these several populations and the high degree of their adaptation to certain ecological conditions the Baikal forage resources are used by the omul at their best (Smirnov, 1974).
The second place in the Baikal fishery is taken by the sor group of fish, such as the roach, the perch, the pike, the ide the crucian and some others. The maximum catch of these kinds of fish reached 4.9 thousand tons. The average year catch in 1968-1981 was about 2.7 thousand tons. In the average yearly general catch of the sor fish according to many years’ data 69% was that of the roach, 23% - of the perch, 5% of the pike, 3% of the ide and the crucian. Other marketable kinds of fish are the grayling, the sig, the sturgeon, some salmon-like fish owing to their relative multiplicity they are interesting as possible objects of fish-breeding as well as of the amateur and sport fishing.
Nowadays such fish-breeding farms work as the Bolsherechensky, Barguzinsky, Selenginsky, Burduguzsky and Velsky producing about 3 milliard grains of omul roe. On the Burduguzsky and Velsky fish-breeding farms incubation is done of the omul spawn which is acclimatized in the Irkutsk and Bratsk reservoirs.
The mammals of Lake Baikal are represented by the only endemic species, the nerpa (seal). According to the morphological and biological signs the Baikal seal is close to the seal which inhabits the Arctic and Far East seas. There are also some features common with the Caspian seal. Grown-up animals are 1.6-1.7 m long and weigh about 130 kg. They reach puberty at the age of 4-6. Females are fertile up to the age of 40-45. In March in snow dens they give birth to one baby weighing about 4 kg and feed it on milk for about 2 months. Mating is in April or early May. Pregnancy is about 11 months long.
Nerpas mainly feed on golomyanka and bullheads. The Baikal seal (nerpa) is spread all over the lake, but it is especially common in its northern and middle parts. The nerpa is a valuable object of hunting. It gives fur, fat and meat.