White whales remember their birthplace – expert

White whales remember their birthplace – expert

23 March 2016

In summer, white whales prefer shallow coastal waters, which are rich in food and convenient for molting and reproduction. As they observed various groups of white whales, scientists came to the conclusion that the whales are tied not only to the same habitat, but also to their place of birth. Viktor Andrianov, PhD in Biology, a senior research associate at the Laboratory of Freshwater and Marine Ecosystems of the Institute of Ecological Studies at the Russian Academy of Sciences’ North Urals Division (Arkhangelsk), talks about the peculiarities of white whales’ reproductive behaviour in the White Sea.


Question: Why do white whales come to the White Sea to reproduce?


Viktor Andrianov: The White Sea is an inland sea. Whales need a place to hide from waves, for example, in a cape. They need shoals that would neutralise waves, like wave-breakers. In many parts of the White Sea there are ridges, on one side of which the sea is rough, while on the other it’s perfectly calm.


There are several thousand white whales in the White Sea. Their numbers significantly increase in summer, when schools from the Barents and Kara Seas arrive for reproduction.


Question: So they need a safe place for their calves?


Viktor Andrianov: That’s right. And the water here is warmer, too. A significant number of calves are born in summer, although some are born in icy waters. This also understandable, because it is safe, even though the water is colder. And cold water is not a big problem, because a newborn calf can weigh as much as 150 kg and it has a sizable layer of fat. The reproductive behaviour of white whales is individual.


Question: Is there a reason for the whales’ attachment to certain places where they produce offspring?


Viktor Andrianov: White whales always use the same places for reproduction. This can be, say, a large and wide rock behind which they most likely give birth. During our expeditions we observed a whale swim with a newborn around that rock near the water surface for quite a long time.


I also saw other whales approach the same rock (there were five and it seemed only one of them was fully mature, the others being calves of various ages) and swim near it. Possibly, all of them were born there.


When calves are born, whales migrate with certain currents. They know the speed of the currents that carry them and the distance from the coast. If they need to return quickly, they move a certain distance away from the shore and a more rapid current returns them to the place they need to get to.


White whales migrate for several hours. They eat on the way and nurse their young with milk for almost an entire year. However, when they return to the place where their calves were born, the latter immediately swim to their birthplace and spend about 20 minutes there. At least this is what happens here. On Solovki [Islands], for example, the situation is a bit different. I had the impression that there is a kind of a specialised maternity “ward” there for white whales perhaps even from different groups.


Whales usually leave the maternity “ward” when calves reach a certain level of independence.


Question: Do calves remain in the whale school or do they start leading an independent life?


Viktor Andrianov: Females, as a general rule, remain in their mother’s group while males join male groups around the age of four or five, when they reach sexual maturity or are close to it.


Male groups go their own ways. They try not to feed near breeding grounds, mostly staying away from them. They can travel long distances – as far as the Barents Sea or the Kara Sea. Males have more room to maneuver in search of food and have their own feeding grounds.


In summer, when whales come to the White Sea for reproduction, there is a swap of sorts of mature whales. Some males remain and some are led away. Sometimes they even stage fights over who will stay and who will leave.


Our observations show that a certain number of males stay with females for the entire summer, among other things, to protect females with calves. I personally observed this scene. During a heavy storm, several white whales, apparently males, swam up to a female with a calf, who both had evidently been unable to get to safety. They stopped around them and lifted the calf, raising it for about a minute, apparently, giving it a chance to catch his breath. Then the males moved away, and the female with the calf swam farther.


Males usually swim in groups of five or six. We saw a large mature female stay with females, while a maturing calf joined the group. It swam with them for several hours but then returned to its own group.


Question: White whales were recognised as an indicator of the status of Arctic ecosystems. Was the behaviour or numbers of white whales affected by the 2003 oil spill in the southern part of the Onega Bay?


Viktor Andrianov: The pollutants entered the waters in September, when white whales usually leave these places together with their newborns. In 2004, they returned but no reproduction activity was observed in the area and they sought to lead older calves away from there. Large white whales approached the area to see what had happened and how badly polluted the bay was.


They returned some time in 2009, but the problem is that white whales lose their adaptive skills when they cannot habitat the places they have become accustomed to. This can lead to higher mortalities. We know about six deaths of mature white whales and calves in that area.


However, it’s possible that the white whales were unable to assess the purity of the water correctly, which resulted in more deaths. Let’s hope that the water eventually returns to normal and fish stocks there will be restored. Then the group will be able to restore its adaptive skills and rebuild their numbers.