Lake Baikal seal, Nerpa
Baikal seals are tiny seals that are members of the family Phocidae. They are native to Siberia and live only within Lake Baikal, from where their common name comes. They are the only type of freshwater seal type and it is still unknown how they arrived in the lake, thousands of kilometers from a seal’s traditional habitat of the sea. The theory is that seals went along the Yenisey and Angara rivers to the Baikal and settled there. The existence of an underground channel between the lake and Lena River and the lake was also proposed, but no scientific basis has been found for this.
The Baikal seal is almost always seen in Lake Baikal in Russia, the world’s deepest lake, though sometimes it is seen in rivers flowing into and out of the lake. It is only found in freshwater. During winter it uses breathing holes, when the lake is nearly completely covered with 80 to 90 cm thick ice.
Habits and lifestyle
Baikal seals live solitary lives, but several of them may gather and share access holes, also sometimes gathering where there is the most favorable habitat. In spring, the time they feed the most, from 200 to 500 individuals will gather, first the juveniles, then adult males, followed by new pups with their mothers. Large groups will also form on the shores of the lake in summer. During winter when the lake is frozen, the seals maintain breathing holes. When the ice starts to thaw, seals gather around larger holes to feed and hunt, mainly at twilight and during nighttime. Baikal seals are dispersed most widely during the winter months. Around the first day in April, they begin to congregate in order to feed near fresh openings where ice has melted. They move in May to the lake’s north end, staying there until they molt. In summer they move to the lake’s southeast corner and use the shore and rocks for hauling out. In autumn, they begin to move back to the areas where the ice is forming.
pod, bob, harem, herd, rookery, colony
Diet and nutrition
Baikal seals are carnivores (piscivores), they feed mainly on fish species that have no commercial value for humans, and juvenile seals sometimes also eat amphipods.
Baikal seals have a polygynous mating system, which means that one male mates with multiple females. Breeding occurs in the spring, usually in mid-April to early June. There is a brief period of delayed implantation, and gestation is for about nine months. Pups are born from mid-February to March on the lake ice. Usually one pup is born, though twins are not unusual. In the case of twins, both usually survive until weaning and then remain together for some time. The mothers nurse their pups from 2 to 2.5 months, though not in the southern area of the lake, where ice breaks up earlier. The pups in the south, being weaned prematurely, are smaller. Females typically reach sexual maturity between 3 to 6 years old and males between 4 to 7 years old. Females can breed until about 30 years old.
Baikal seals have been hunted for a very long time for pelts, oil and meat. Such harvesting continues today, although at such a level that it is believed not to threaten the species’ survival. But pollution of the lake is a threat, with this ‘pearl of Siberia’ affected by towns and factories on its shores, which pollute the water with industrial waste and sewage, and the use of pesticides and fertilizers on the agricultural land nearby. Disease is also a threat; an outbreak in 1978 and 1988 of the Phocine distemper virus caused the deaths of an estimated 6,500 seals, and the virus is still alive within the population. Furthermore, global warming threatens the deterioration of the quality of the habitat of the Baikal seal, and may cause a population decline.
According to the IUCN Red List, the total Baikal seal population size was estimated to be around 108,200 individuals in 2013, with an estimated pup production of 23,600 individuals. Currently this species is classified as Least Concern (LC) and its numbers today remain stable.
Being piscivores, these animals affect fish populations in their range. Baikal seal is the crown of the Lake Baikal’s great ecosystem and its only mammal.
Fun facts for kids
- Baikal seals typically dive to 10 to 50 m for between 2 to 4 minutes when hunting prey.
- Baikal seals, especially the females, are seen to be more graceful than other types of seals.
- Baikal seals have an extra 2 liters of blood, which means they can hold their breath for as many as 70 minutes.
- Baikal seals can dive as deep as 400 m.
- Baikal seal use their whiskers to locate potential prey. Each day adults will eat 3-4 kg of food, which is more than a ton of food in a year.
- The Baikal seal can give birth to twins, one of the few seal species to do so.
- These seals have been blamed for a decrease in the numbers of "omul", a species of fish that lives in Lake Baikal. But this is not true, as the main source of food for the Baikal seal is the fish “golomyanka”. By eating great quantities of these fish, they actually help the omul’s competition for resources.