Acipenser baeri baicalensis Nikolski, 1896
From the evolution point of view, the Baikal sturgeon is the most ancient and the largest fish of Lake Baikal. The first information on the Baikal sturgeon can be found in the reports of the archpriest Avvakum and Nikolay Spafary, who visited the wonderful lake at the beginning of the XVII century. I.G. Gmelin (1751) also mentioned a considerable amount of the sturgeon describing his trip through Siberia. At the end of the 17th century, I.G. Georgi, a naturalist-researcher, gave a detailed description of the sturgeon, which dwelt in Lake Baikal, as well as commercial fishing of this valuable fish in the Selenga River. A.G. Egorov had been studying Baikal sturgeon for many years. He carried out a great deal of work studying distribution, abundance, biology, and commercial fishing of the sturgeon in different areas of Lake Baikal – bays and river mouths. The results of his investigations were published in some scientific papers and in the book “Baikal Sturgeon” (1961). A. Egorov noted that different peoples named the sturgeon differently: e.g. Mongols and Buryats – khelma, Evenks – tina, Yakuts – khatys, Gilyaks – tukkicho, and Golds – kirfu or kilfu. A famous Russian writer V.P. Astafyev named the sturgeon a “tsar-fish”.
The sturgeon is the only representative of cartilage fish in Lake Baikal forming a special subspecies. The colour of the sturgeon varies from light-brown to dark-brown. The abdominal side of the sturgeon is always light. There are five rows of bone scutes along the whole body between which there are small bone plates of different forms. The upper lobe of the tail fin is longer than the lower one. The mouth of this fish is low. In front of it there are four pairs of barbells. A juvenile fish has a longer snout than an adult.
The sturgeon inhabits mainly the depth of 20-50 m in the delta of the Selenga River, mouths of some rivers, and bays of Lake Baikal. In autumn, when there are strong winds, the sturgeon descends to the depth of 150 m. It winters in pits in the mouths of large rivers. Fattening and spawning migrations are also observed in the sturgeon. The average linear growth of this fish makes up 5-7 cm a year.
Males become mature at the age of 15-16 years (1 m long and 6-7 kg of weight), while females – at the age of 18-20 years with the body length of 100-120 cm and weight of 12-14 kg. After spawning the fish rests and re-spawns in one-two years. A modal (typical) group of the spawning flock consists of males of 15-28 years and females of 20-37 years. The fecundity of the sturgeon depends on the linear sizes and weight: the larger the female, the higher level the fecundity. There are 253,000 hard-roes in females of 140 cm long, while in those of 181 cm long and 39.5 kg of weight – 832,000 hard-roes. The diameter of a roe varies from 2.4 to 2.9 mm with the weight of 15.2-15.6 mg. Reproduction of the sturgeon takes place in such rivers as the Selenga, Upper Angara, and Barguzin. Spawning migrations begin in April. The sturgeon enters the rivers in a great number in late May-early June when the water temperature varies from 3-5 to 14-16ºC. Spawning takes place at 10-15ºC. Hard-roes grow on the stony-pebble substrate for 7-15 days at water temperature of 12-18ºC. Hatched larvae of 10-12 mm long stay in the rivers. Then in autumn they partly migrate to the river mouths and to Lake Baikal where they stay for wintering.
Baikal sturgeon at young age
The sturgeon feeds on benthic organisms from shallow areas; mainly they are amphipods, juvenile fish, larvae of chironomids and other insects. There is also detritus, sand, and silt found in the stomachs of the sturgeon. There are age and seasonal changes in the sturgeon feeding. For example, crustaceans prevail in the food of juvenile fish, while in adults – young fries of different fish. In spring-summer period the main components of food may be mayflies, stone flies, whereas in winter – sculpins.
Different parasites have been registered in the Lake Baikal sturgeon: flukes, flat worms, nematodes, acanthocephalans, and leeches. Leeches are located on the fins and gill covers. The highest number of parasites is recorded in winter when the sturgeon is not very active. The longevity of the sturgeon is 50-60 years.
The commercial fishing of the sturgeon goes back to the ancient time. When the Russians settled around the lake, the fishing increased with the use of more advanced fishing gear. I.G. Georgi wrote in 1775 that “the omul was a daily bread for merchants, whereas the sturgeon provided them with wealth”. At the end of the XVII century there was observed a significant exploitation of fish resources which belonged to the Posolsk Monastery. The highest catch of the sturgeon made up 250-300 tons a year, one fish weighing 150-200 kg (the second half of the XIX century). As a result of intensive catch of juvenile and spawning fish, the reserves of this species considerably reduced, and beginning from 1945 there was a ban on its fishing.
The Baikal sturgeon is listed as an endangered species in the Red Book of the Russian Federation and in the Red Book of Buryatia. It is necessary to continue studies on biology of the sturgeon and to breed juveniles under artificial conditions in order to increase its abundance in the lake.