They feed their young on milk twice as long as other seals.
The Nerpa is one of the smallest true seals. The seals have a uniform steely-grey coat on their backs and fur with a slightly more yellow tinge coating their stomachs. As the coat weathers, it becomes brownish. When first born, the seal pups are around 4.5 kg and have a coating of white silky natal fur. This fur is quickly shed and exchanged for a darker coat, much like that of the adult.
It is still a great mystery how nerpa appeared in the centre of the Asian continent, if its relatives live in the northern arctic regions, but it is estimated that they have inhabited that location for some 2 million years.
The areas of the lake in which the Baikal Seals reside changes depending on the season as well as some other environmental factors. The Nerpas are solitary animals for the majority of the year, sometimes living kilometers away from other Nerpas. In general, there is a higher concentration of Nerpas in the northern parts of the lake, because the longer winter keeps the ice frozen for longer, which is preferable for popping. However, in recent years there have been migrations to the southern half of the lake. These are speculated to be evasive action against hunting. In the winter, when the lake is frozen over, they maintain a few breathing holes over a given area, and tend to remain to that area, not interfering with the food supplies of a nearby neighbour. When the lake begins to melt, the Nerpas tend to stay around the shorelines.
Female Nerpas reach sexual maturity at 3-6 years of age, whereas male Nerpas reach it around 4-7 years. With a combination of delayed implantation and a 9-month gestation period, the Nerpa’s overall pregnancy is around 11 months. Nerpas usually give birth to one pup, but they are the only seal with the ability to give birth to twins.
The mother Nerpa will feed her young for around 2.5 months, nearly twice as long as any other seal. During this time, the pups can increase their birth weight (around 4 kg) fivefold. After the pups are weaned, the mother will introduce them to solid food, bringing shrimp, fish, and other edibles into the den.
Every year in the late winter and spring, both sexes will haul themselves out and begin to moult their coat of fur from the previous year, which will be replaced with a new one. While moulting they do not eat and enter a lethargic state, during which time they often die of overheating, males especially, from lying on the ice too long in the sun. During the spring and summer, groups as large as 500 can form on the ice floes and shores of Lake Baikal. At present the number of seals is estimated at around 70 000 – 100000 heads.
Big and small Golomyanka (Comephorus baicalensis and Comephorus dybowskii)
The golomyanka or Baikal oilfish are two species of Baikal oilfish, peculiar sculpin-like species endemic to Lake Baikal in Russia. They are easily identifiable, and are large enough (at 15-20 cm) to be easily seen. Golomyanka are unusual for their habit of moving throughout the entire water column of Lake Baikal without much regard for changes in pressure, although they can exist only within a very narrow range of temperatures and generally tend to find their ecological niche at 300-800 m.
They are considered the world's most abyssal freshwater fish. They are also known for rapidly decomposing in sunlight, leaving behind fat, oil, and bones. Golomyankas have a naked, glassy body that is dull and translucent in appearance. They have long pectoral fins and although pelvic bones are present they lack pelvic fins. Golomyankas have a strong lateral line. The lateral line system on the head consists of large cavities linked by narrow bony bridges with small external pores. Lack of a swim bladder, high lipid content and porous bones are what allow the fish to tolerate varying pressure extremes as it moves through the water column.
The biomass of the golomyanka population is estimated at anywhere from one hundred thousand to one hundred fifty thousand tons, making it one of the most populous forms of vertebrate life in Lake Baikal.
Baikal omul (Coregonus autumnalis migratorius Georgi)
Baikal omul is a relatively abundant whitefish species of the salmon family endemic to Lake Baikal. It is considered a delicacy and is the object of one of the largest commercial fisheries on Lake Baikal.
There are four or five traditionally accepted subpopulations within Lake Baikal. These vary in size, feeding behavior and preferred spawning habitats. The extent of their reproductive isolation is debated.
The omul is a slender pelagic fish with light silver sides and a darker back. It has small spots on its dorsal fin and larger ones on its head, a terminal mouth and a large number of gill rakers, typical of fish that feed in the pelagic zone. The mean size of adults is 36-38 cm and 0.6 to 0.8 kg, though there are maximum reported lengths of 56 cm weighing about 2.5 kg. The subpopulations on the northern end of the lake tend to be smaller.
The omul feeds primarily on zooplankton, smaller fish and occasionally some benthic organisms. It feeds primarily in the rich pelagic zone of Lake Baikal up to 345-450 m. They are a relatively long-lived, iteroparous species that attains reproductive maturity at five to 15 years of age. The omul only enters the rivers that feed Lake Baikal to spawn, initiating short spawning migrations usually in mid-October, broadcasting 8000-30000 eggs before returning to the lake.
Epishura (Epishura baikalensis)
This is one of the most well-known invertebrates of Baikal. This small, 1.5 mm long crustacean plays an important role in the pelagic ecosystem. It consumes the majority of Baikal algae and serves an essential feeding object of famous omul. The epishura plays an exceptional part in Baikal's life circle. Without any exaggeration, one can say that the epishura is the major filter of Baikal. According to academician G. Galazy, a well-known scientist (Lake Baikal, 1979), throughout the year all crustaceans of this species filter from 500 to 1,000 cubic km of the Baikal water or more, which is 10-15 times more the annual inflow of water from all tributaries. The epischura lives only in cold clean water with constant chemical composition and high saturation with oxygen. Biomass of Epishura and cyclop (aprox.) = 1800000 ton.
One-celled and small invertebrate animals, inhabiting the Lake pelagic zone are joined into zooplankton group. They posess such apparatus, that support them in water body. They are free-moving together with Lake waters and occur up to great depths. Total biomass of zooplancton = 4600000 ton.
