Why are killer whales suddenly attacking boats?

Chris Smith asked marine scientist Liberty Denman...

Liberty - This is a very hot topic now, as you say, and I must be honest, I'm not entirely sure how long it's been going on, but I do know that it has started increasing in frequency as well. And I think we are safe to say that, short of being an orca, we can't one hundred percent say what the reason is. The current assumption from experts around the world is that, quite simply, they're playing and having fun as all mammals, us included, do. They like to have fun. The problem is they're having fun by ramming boats and removing rudders from them, which tends to result in them sinking, which, even being the hardest of nails, you might want a change of underwear after that. So I can understand the fear from it, but the general assumption is they are playing.

Liberty - There are a few conspiracy theories that have come out after it, which I think always grab the attention, don't they? If you look back historically, we haven't had a fantastic relationship with the species, us being the perpetrators. There's been no recorded kills of orcas on humans in the wild, but unfortunately we have had them captive and unfortunately still do in some places. And they're very emotional creatures and they also have incredibly good memories. And when they are in the wild, they live in pods, they're matriarchal, which means they learn from the female figures and it's often their grandmothers that they learn the most from. They provide the teachings really. And as a result, one of the conspiracy theories is that this one particular orca, female grandmother orca, had a poor experience with the sailing boat and then decided to teach the others within the pod to start doing this. As I said, I'm convinced that that's probably not the best case scenario and the assumption is that they are in fact just playing and having fun. But we don't know.

Chris - Is it true that there was one particular orca who started wearing a dead fish on its head and then all the other orcas in the area started copying? This example of orca culture that's spread across a huge region. Because dolphins do that with sponges, don't they? In Australia, there's a sponging population of dolphins that put these sponges on their noses to ostensibly protect their noses when they're ferreting through the subsurface?

Liberty - I mean all of this really tells you that ultimately cetaceans, these whales and dolphins, know how to have fun and they enjoy doing this. And they're also incredibly emotional creatures, the way they actually have a more extensive brain than ourselves and have the ability to experience and process emotions to a greater extent than we do, which is also why, on the captivity side, you can hear quite literally in their communications and their cliques that they are deeply unhappy also with that culture as well. There are different pods and it goes across cetacean species, that they all have a slightly different dialect sometimes and communicate in different ways. So they have communities in the same way we do as well.