|Research by neurobiologists has shown that dolphins and whales, along with some higher primates, can experience not just pain but also suffering [AFP]
There are about one and a half million whales in the world's oceans, but pollution, climate change, fishing and confusing sonar signals from ships are among the many challenges to their survival.
The most direct threat to their existence, however, is whaling.
Commercial whaling was banned in 1986. But despite the moratorium, at least 30,000 whales have been killed by Japan for so-called scientific research, and Norway and Iceland under their home-grown quota system.
The Japanese fish out at least 1,000 Minke whales a year. There are about half a million of them worldwide – but conservationists say overfishing in the Antarctic is pushing certain Minke populations to the point of extinction.
Endangered species are on the menu too. Hundreds of Sei whales, the fourth largest species, are killed in the Pacific ever year.
Fin whales, the second largest at a massive 22 metres-long, are another meaty target for whalers. Japan and Iceland catch more than 50 between them a year. That is despite the fact that they are endangered, and only a few metres shorter than the biggest mammal in the world – the Blue whale.
However, the biggest question that scientists pose does not even figure in talks at the International Whaling Commission. It is the notion that whales are intelligent and sentient beings and not just an animal commodity.
Some scientists say marine mammals are not only smarter than once thought but also share several attributes once claimed as exclusively human.
Self-awareness, suffering and a social culture along with high mental abilities are a hallmark of cetaceans, an order grouping more than 80 whales, dolphins and porpoises, marine biologists say.
A decade ago, Lori Marino, a neurobiologist at Emory University in Atlanta, Georgia, conducted an experiment with bottlenose dolphins in which she placed a small mark on their body and had the mammals look at themselves in a mirror.
By the way the dolphins reacted to the image and then looked at the spot, it was clear that they had a sense of self-identity, Marino determined.
Georges Chapouthier, a neurobiologist and director of the Emotion Centre at Pierre and Marie Curie University in Paris, said self-awareness means that dolphins and whales, along with some higher primates, can experience not just pain but also suffering.
Unlike nociception, a basic nerve response to harmful stimuli found in all animals, or lower-order pain, "suffering supposes a certain level of cognitive functioning," he said in an interview.
"It is difficult to define what that level is, but there's a lot of data now to suggest some higher mammals have it, including great apes, dolphins and, most likely, whales."
As for intelligence, cetaceans are second only to humans in brain size, once body weight is taken into account.
More telling than volume, though, are cerebral areas which specialise in cognition and emotional processing, and the likelihood that this evolution was partly driven by social interaction, according to several peer-reviewed studies.
"Evidence is growing that for at least some cetacean species, culture is both sophisticated and important," Hal Whitehead, a professor at Dalhousie University in Halifax, in the Canadian province of Nova Scotia, said.
"At any time during the winter breeding season, all the males in any ocean sing more or less the same elaborate song, but this communal song evolves over months and years," Whitehead and colleagues noted in a study in the journal, Biological Conservation.
Scientists have also observed orcas, or killer whales, learning from other orcas from a geographically separate group how to steal fish from so-called longlines used by commercial fishing boats.
"If we wipe out a sub-group, it is more than killing a certain number of individuals. It could actually wipe out an entire culture," Marino said.