Welcome to the wondrous world of whales
Published: 19.03.2019 Updated: 03.04.2019
“What is unusual about whales is that although they are mammals, they live their whole lives in the water – from A to Z”, explains Nils Øien, an expert on whales at the Institute of Marine Research (IMR). He has been studying whales for over 30 years, but these ocean giants never cease to fascinate him.
“I often think about bowhead whales, which can grow incredibly old. Imagine living for 250 years and spending your whole life in the water”, says Øien.
The paradox of whales: why do they live in the water?
These big mammals only spend a fraction of their lives at the surface, which is the only place where they can breathe. So why did they end up living in the sea?
“Obviously an evolutionary adaptation took place, and then they discovered that it’s a very good place to live”, says Øien.
One of the advantages of living in water is that they don’t have to “battle against” the force of gravity in the same way that land mammals do.
“It isn’t a coincidence that blue whales are the biggest animals ever to have lived. The water provides support for their bodies. A body like that would never have been possible if it had to be supported by legs”, says Øien.
The longest blue whale in the world, observed in the Southern Ocean, was measured at between 33 and 34 metres long. However, it wasn’t the heaviest whale ever recorded. That award goes to a whale with a match weight of 180 tonnes. For comparison, there were dinosaurs of a similar length to blue whales, but none of those ancient reptiles can match the body mass of the giant of the oceans.
Stranding affects deep-divers
Although whales spend most of their lives below the sea surface, there are only a few species that are genuine deep-divers. In our northern waters there are two main ones: the sperm whale and the Northern bottlenose whale.
“They dive down to depths of at least 2,000 metres, where they feed on animals like squid”, says Øien.
The whales swim up and down almost vertically – after all, they are roughly the same shape as a submarine, explains Øien. But there is evidence that the return to the surface doesn’t always go well.
At regular intervals we hear stories of mass deaths, where groups of whales have inexplicably become stranded.
“These cases almost always involve deep-divers. So researchers have started wondering whether they have been scared by military exercises, seismic surveys, sonar or something like that, which has affected their return to the surface and caused a kind of decompression sickness”, says Øien.
“The causal mechanism is not yet understood, but it is striking that deep-divers are the ones affected by mass deaths, and that these cases often occur in conjunction with military activity in the area”, he adds.
Tired whales need a snooze
Like all mammals, whales need to rest. But they have different ways of doing that.
“Some species of dolphin can turn off half of their brain at a time, which means they don’t need to sleep”, Øien tells us.
In the case of the bigger whales, however, there is strong evidence that they have a snooze while floating at the surface. They literally float off to sleep.
“During our whale tagging trip to the Barents Sea last autumn, we saw a pod of six or seven humpback whales lying there in a row on the surface having a snooze”, says the whale expert.
“They didn’t sleep for very long, but they probably have a break like this every once in a while.”
Travel enormous distances
It’s not surprising that whales need a rest every now and then. After all, they travel enormous distances.
“The longest journey we have documented was made by a satellite-tagged humpback whale that travelled a distance of 7-8,000 kilometres”, says Øien.
Last autumn, researchers from the IMR put satellite tags on humpback whales in the Barents Sea to track their migration to the Caribbean. That’s a trip of about 6,000 kilometres.
“In the Southern Ocean, scientists also observed a whale that was feeding right down by Antarctica head straight to the calving grounds north of Australia”, says our whale expert.
Mr Porter dropped by for a visit
The Norwegian coast has also been visited by whales from far away. Øien tells us that in 1999, a rather unusual whale was observed at Kvænangen. It turned out to be a right whale, so he sent some photos of it to colleagues in the United States. He knew they had a good archive of the 300–400 individuals in the right whale population that lives off the east coast of North America, which is one of the most vulnerable whale populations in the world.
“They were immediately able to confirm that it was Mr Porter, a whale that had first been observed there in 1983.
The year after visiting Kvænangen, Mr Porter was seen back on the east coast of America.
“So he got safely back from his holiday”, says Øien.
A short break to the Caribbean
Research on the migration patterns of whales has taken a dramatic leap forward as satellite tagging takes over from the traditional method based on direct observation.
“We used to think that it was really simple: the whales came here to eat, and then they had an area where they overwintered and gave birth to their calves. But actually it’s not that simple”, says Øien.
Scientists used to think that the orcas in Lofoten overwintered in Tysfjorden, but that was until they put satellite tags on some of them.
“Do you know what happened? They took off. Some of the whales had a Christmas holiday in Møre, while others headed out into the Norwegian Sea and then returned. So this has given us a completely new perspective”, says Øien.
Satellite tagging has also left scientists scratching their heads as to why humpback whales migrate from the Barents Sea to the Caribbean each autumn. It started with an Icelandic humpback whale that travelled to the Caribbean, but only stayed there for just over a week before heading north again.
“We also have an example from Norway of a whale that only stayed down there for a few hours before returning north. That leaves us wondering what they’re actually doing down there”, says Øien.
“From an evolutionary point of view, the migration may have become such a strong part of their instinct that it forms part of their natural cycle.”
The biggest whales often lead lonely lives out in the oceans, but toothed whales, like orcas, frequently form family groups.
“These are often matriarchal groups. In other words, the mothers and daughters work together, whereas the males have a less settled lifestyle”, says Øien.
Genetic research has shown that the males that accompany a family group are not the fathers of the calves. During the mating season, they leave their own group and seek out other groups.
“This is probably a mechanism to maintain a certain amount of genetic diversity; basically to avoid inbreeding”, says Øien.
Males being forced out of the family group is also common amongst land mammals.
“When males reach sexual maturity, they are chased out.”
“Speak” to each other across thousands of kilometres
The ocean giants are social animals that use sounds to communicate with each other.
“We know that some species of baleen whales produce a kind of song. I don’t know whether I would call it singing, but at least it’s a kind of grunting”, says Øien smiling.
“It’s at a very low frequency, outside the range of the human ear.”
The low frequency enables whales to “speak” to each other across incredible distances.
“They can communicate even if they are several thousands of kilometres apart”, says Øien.
He first noticed this many years ago when Icelandic scientists put radio tags on some fin whales. Suddenly they observed one of the whales travel from the coast of Iceland through the Denmark Strait to the coast of Greenland, where there was another group of fin whales.
“They must have sent a signal that there was food available and that the conditions were good”, says the whale expert.
Seduced by propellers
Whales can also be seduced by sounds that aren’t whale song. This is particularly true of young minke whales.
“Young animals tend to be inquisitive; that’s pretty universal. And that often means putting yourself in harm’s way”, says Øien.
“So young, inquisitive whales often approach a boat because they think it’s making a nice sound”, he continues.
Old whaling boats had a particularly seductive sound. Some of them were better for whaling because inquisitive whales were more likely to approach them. That made it easier to hunt the animals.
“Some of the boats simply made a more attractive sound, which we think was something to do with the propellers. Some boats are also better for doing whale research, precisely because they don’t frighten off the whales,” says Øien.
Decimated the blue whale population
Whaling has had a big impact on some species, particularly in the Southern Ocean.
“In 1930, the annual blue whale catch was around 30,000 individuals. That’s a huge number — absolutely unimaginable. They completely decimated the population”, says Øien.
As a result, the blue whale population in the Southern Ocean was reduced to just one percent of its original size. Fin and humpback whales were also hunted in the Southern Ocean, but the humpback whale population has now recovered to its pre-whaling level.
So why have humpback whales managed to flourish again, but not blue whales?
“I think it’s related to the fact that blue whales only eat plankton, whereas humpback whales are less picky. They’ll eat almost anything they find. And last but not least, humpback whales may have a more effective grazing strategy, because several individuals often cooperate to find and concentrate their food”, says Øien.
Our expert’s favourite whale
Minke whales are still hunted in Norwegian waters, and it was the management of this whaling that got Nils Øien involved in in whale research. But after studying the giants of the oceans for over 30 years, which is his favourite whale?
“That must be the humpback whale, because it’s the easiest whale to get close to”, he says, before adding:
“I should really answer the minke whale, because that’s essentially what my work is about, but it’s such a difficult whale to work with. It doesn’t really draw attention to itself. Humpback whales, on the other hand, are spectacular; they’re exhibitionists who love showing off.”