The Excerpt podcast: Orcas are sinking boats. What gives?

On a special episode of The Excerpt podcast: Last November, orcas sank a yacht in the Strait of Gibraltar. This wasn't anything new; these marine mammals have sunk vessels several times over the past few years. The question is why. Orcas have highly complex social structures and there's a lot we don't understand about their behavior. Can studying their interactions with boats give us some insight? Michael Weiss, research director at the Center for Whale Research, joins The Excerpt to discuss these highly intelligent and social marine mammals.

Hit play on the player below to hear the podcast and follow along with the transcript beneath it. This transcript was automatically generated, and then edited for clarity in its current form. There may be some differences between the audio and the text.

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Dana Taylor:

Hello and welcome to The Excerpt. I'm Dana Taylor. Today is Thursday, January 4th, 2024, and this is a special episode of the Excerpt. Orcas have been making headlines this year, mostly due to some unusual interactions with boats. Last month they sank a yacht in the Strait of Gibraltar, one of several times they've sunk a vessel over the past few years. The question is why? Orcas have highly complex social structures. Can studying their interactions with boats help us understand them better? Joining us now to discuss these highly intelligent and social marine mammals is Michael Weiss, Research Director at the Center for Whale Research.

Thanks for being on the Excerpt, Michael.

Michael Weiss:

Yeah. Thanks for having me.

Dana Taylor:

I mentioned the interactions that orcas have been having with boats, some taking aim at rudders. According to a study in the Marine Mammal Science last year, there have apparently been hundreds of interactions between orcas and boats over the last several years. Do researchers know what's causing this behavior?

Michael Weiss:

Yeah, I wouldn't say that researchers know. There are certainly quite a few theories and hypotheses. And they range all the way from one of these animals had a negative interaction with a boat and is now reacting negatively to them to what I kind of think is going on and what most researchers I've talked to think is going on, which is these animals have found a new way to play, essentially. And they're very curious about the world they live in, they're very interested in finding new ways to mess with objects, and they learn from each other. So you get one whale starting to mess with boat rudders, and then the next whale picks that up and the next one picks it up, and soon you have a whole group of animals all with this novel behavior.

Dana Taylor:

So I was going to ask, because I read that orcas are sort of famously known for picking up behaviors from each other, causing trends. One example was an orca that carried around a salmon on its head in Puget Sound in the '80s. What are some other unusual trends that you've come across?

Michael Weiss:

There are other trends we see in these whales, for example, in the population where these kind of, quote, unquote, attacks are occurring, there's whole groups of the killer whales there, including the whales who are doing this, interact with the boats who learned to depredate fishing lines, tuna fishing lines. So these whales, normally their natural behavior is to chase tuna, kind of exhaust them and catch them and eat them. But a whole kind of family of these whales, a whole section of the population really learned to just pick the salmon right off the lines of fishermen, getting an easy meal. Killer whales seem to be really good at specifically learning these things that involve hunting and getting food.

But we also see whales do less useful things. There's one whale in the area that I do my research who has become notorious for finding crab pots and other fishing gear and messing around with it and playing with it till someone sees him and thinks he's entangled and needs help. And the entanglement team is deployed and they go out to try to help the whale, and by the time they get there, he's gone and he's doing just fine. So they're very good at social learning and they're very good at finding ways to get themselves into trouble.

Dana Taylor:

So I know that orcas are apex predators. Just this month, there were boaters in Monterey Bay, California who watched a pod of them hunt and kill, I believe it was a minke whale. How do they hunt and how does their choice of prey vary among different pods?

Michael Weiss:

So like you mentioned, there are whales throughout the world that eat marine mammals, other marine mammals, including large whales. In fact, off the coast of Australia, they've observed killer whales hunting full-grown blue whales, which is the largest animal on the planet. You have whales that kind of specialize in hunting sharks, in some case great white sharks. And then you have whales like the southern resident killer whales that I study in Washington State and British Columbia who are salmon specialists. They're fish eaters and they don't really eat anything else. So they eat a bunch of different things. Some whales are more specialized than others. These whales that are interacting with boats are, we think, maybe not specialists, but they seem to really like tuna. Tuna is one of the main things they eat. And they learn how to hunt those things usually from their mom or from other whales in their social environment. And that can be super specialized.

Dana Taylor:

Well, I mentioned that orcas are known for their complex social structures. Can you give us an overview of what those structures look like?

Michael Weiss:

Yeah. So there's a lot of variation. But in general, the killer whales that have been studied around the world tend to be matrilineal. So you tend to have social units made up of moms and their kids and sometimes their daughter's kids as well. The extreme of that is these salmon eating whales I've been talking about where both sons and daughters never leave their mom's group. But in general, killer whale society is very focused on the bonds between mothers and their offspring.

Dana Taylor:

Okay. So let's talk a little bit more about their social behaviors. How do they interact and communicate within their pods?

Michael Weiss:

Killer whales generally live in a very acoustically focused environment, and you can see that in their brains, the parts of their brain that are designed for processing auditory information are hugely enlarged and complicated. So you can have whales spread out over a really long distance, 10 kilometers who are still in vocal communication with each other, making these what's called pulsed calls. These calls are often specific to matrilines and to pods. So different groups, even within the same population, sound different. And we think one of the big functions of these acoustic calls is to maintain contact between family members as they're traveling and sometimes spreading out over large distances. But in addition to this kind of general interaction with their calls, they're also really, really tactile and social. So you'll see them in these big groups spending a long period of time just rubbing on each other, playing, pushing each other around a bit, sometimes roughhousing, especially the young whales.

Dana Taylor:

Well, something that I came across on your group's website that really intrigued me was that orcas are the most cosmopolitan of all marine mammals. How has that affected your ability to study their behavior?

Michael Weiss:

As you might've been able to tell from how I've responded to all these questions, we have to be careful when we generalize. So we can study the populations we work on and begin to understand things about what drives their social structure and their behavior. And we can look at what people have found in other populations and start to see commonalities. But we have to be careful when we generalize. In the same way we have to be careful when we talk about what is human social structure and human social behavior. It varies hugely between societies and cultures. So really just trying to find what we can that is general while avoiding making any rash generalizations.

Dana Taylor:

Well, you talked about some of the way orcas interact with other marine species, they could be prey. But overall, what's their role in helping to maintain the balance of marine ecosystems?

Michael Weiss:

So killer whales are top predators. So they are sitting at the top of these food chains. In cases where they're eating things that reproduce rather quickly or are these kind of exploding populations, they can serve as really good kind of biological controls. That's really the role that top predators tend to play in ecosystems is as a control on other populations that if left without predation might explode to the point where they run out of food or they cause other populations to run out of food, and disrupt kind of that delicate balance.

Dana Taylor:

So let's turn now to conservation. Our oceans are changing due to climate change. What are some of the current conservation challenges facing orcas and what efforts are being made to protect their habitats?

Michael Weiss:

So in general, killer whales face two large threats. One is the changing in oceans due to climate change, and that's causing collapses up and down the ecosystem. So like I said, killer whales are top predators. They can help regulate ecosystems. But that also means they're potentially vulnerable. They're sitting at that top of the pyramid and if you start taking pieces of the food web away, they could be some of the first animals to really feel that effect.

The other thing that killer whales are facing worldwide is toxins, especially persistent organic pollutants like PCBs. These are things typically used in manufacturing or different forms of industry that get put out into the ocean. And like their name suggests, they are persistent in the environment. They don't really go away. And what happens is they end up getting taken up by small microorganisms and plants that then end up being eaten by something else and eaten by something else. And you get what's called biomagnification, where a substance that's actually quite rare or diluted in the ecosystem generally gets magnified at the top of the food chain, and killer whales are at that tippy top. So killer whales are some of the most toxic mammals on the planet, period, because of this bioaccumulation. And a lot of the things that are accumulating that we've put into the environment are going to have effects mostly on their immunity and on their reproduction.

Dana Taylor:

And I was going to ask how do human activity such as overfishing impact their ecosystems?

Michael Weiss:

So there are cases where the whales might be in direct competition with fisheries and these whales in the Strait of Gibraltar and around the Iberian Peninsula are also potentially in direct competition with tuna fisheries. But whales can also come into indirect competition with fisheries when they might be eating the animals that are also relying on the same thing that fisheries do. A great example of that is the krill fishery in the Southern Ocean, which krill are a huge sustaining force for baleen whales for a lot of large whales. Those whales might then also be killer whale prey, not just the large whales, but also a lot of other marine species that might also be killer whale prey. So it's really this indirect competition where humans come into competition with the things killer whales eat versus potential direct competition where we're trying to eat the same thing as the whales.

Dana Taylor:

There's been an increase in mass stranding events, MSE. Involving pilot whales. First, what is an MSE? And is this behavior something that we see with orcas?

Michael Weiss:

Yeah, so a mass stranding event, like the name implies, is an occasion where a large number of animals simultaneously strand on land, either alive or dead. And it can be caused by a lot of things. And we're also not totally sure what causes all of these events. They're more common in social pelagic species like pilot whales and false killer whales. And we don't really see mass strandings in killer whales. And it's not totally clear why we don't, given that they have actually quite similar social structure to pilot whales. They're similar size, kind of similar ecological niche. But they do live in different places. They tend to live in slightly different areas. While pilot whales live in kind of deep water and are deep diving species, killer whales tend to be more associated with coasts and shoreline and tend to stay closer to the surface.

We do see killer whale strandings. Killer whales do strand sometimes in very strange places, like a while ago there was a killer whale stranded on the coast of Florida. But they don't tend to strand in large numbers. You tend to kind of get one or two at a time.

Dana Taylor:

Okay. And then finally, Michael, what would you like people listening to understand about these incredible marine mammals?

Michael Weiss:

I think especially given what we started talking about with why killer whales have been in the news so much lately with these interactions with boats, I think it's just important to understand killer whales, well, we want to avoid anthropomorphizing them. We don't want to project what we feel onto them or human feelings or emotions onto killer whales. I think it's also important to understand the ways in which they are very much like us. They live about the same amount of time as we do. The females stop reproducing at about the same time humans go through menopause. They live in these tight-knit social groups that have kind of taken over the world a little bit in the same way humans have.

And along those lines, they're like us in that sometimes they'll do things we don't fully understand. Sometimes they'll exhibit behaviors that aren't directly related to finding food or to their immediate survival, and also aren't some moralistic crusade against yachts, as much as I love that narrative and think it's quite fun to talk about. Sometimes they're just animals interacting with their environment in a way they find amusing. Just like, why do kids in the country go cow tipping? Well, because they don't have anything else to do, really. So I think it's important to understand killer whales as complicated cultural and curious animals who will behave in ways we don't ever fully understand.

Dana Taylor:

Thank you so much for joining us on the Excerpt, Michael.

Michael Weiss:

Yeah, thanks for having me. This is great.

Dana Taylor:

Thanks to our senior producer Shannon Rae Green for production assistance. Our executive producer is Laura Beatty. Let us know what you think of this episode by sending a note to [email protected]. Thanks for listening. I'm Dana Taylor. Taylor Wilson will be back tomorrow morning with another episode of The Excerpt.