About a decade ago, great white sharks were popping up in South Africa on beaches without their livers. They were dead and they were just lying there, just carcasses were gone, and people were like, "What is going on with these livers?" Later found out that there were two orcas named Port and Starbird that would come in every once in a while and kill said great whites. And these great whites are known to be massive. They're like 18 footers, 20 footers, and they were typical of that area.
That's where air jaws started. They were revered for what they could do, and that's jump out of the water as they're attacking the seal. They were the apex predator of the area until these orcas came by. That fueled a lot of research to find out why these orcas are going after these livers, what's happening, and until recently, we haven't really seen DNA evidence of this happening. We haven't really seen that, hey, these shark bites are from orcas.
We haven't really seen these bites on the sharks that are actually from orcas until now. There was a paper that was recently released that was published in Ecology and Evolution, a peer-reviewed journal article that actually says genetic evidence of killer whale predation on white sharks in Australia. Now, I've been talking about South Africa because Port and Starbird, the orcas that have been around that have actually been killing these great white sharks are in South Africa.
Now, they actually have DNA evidence in Australia. We're going to talk about why this is so important on this episode of the How to Protect Yours podcast. Let's start the show. [Music] Hey, everybody. Welcome back to another exciting episode of the How to Protect the Ocean podcast. I'm your host, Andrew Loewen, and this is the podcast where you find out what's happening in the ocean, how you can speak up for the ocean, what you can do to live for a better ocean by taking action.
On today's episode, we're going to be talking about just eating great whites. I know I've talked about this before, but now we actually have genetic evidence that shows there are some orcas that are eating great whites in Australia, not just South Africa, but in Australia. This is a pretty big deal because we've seen videos of orcas attacking sharks before. We know they're an apex predator. We know they go after other apex predators, but orcas truly are the apex predator of the ocean.
They're smart. They hunt together. They're fast. They're enormous. And like I said before, they're smart and they're going to go after these great whites. But we haven't really seen genetic evidence of these great whites actually biting sharks. We know they go after the liver because the liver is so dense in nutrients that there's a reason why they go. Orgas have been known to attack bolamolas. They've been known to attack a lot of different sharks, blue sharks and so forth.
But we didn't really know until recently and I mean recently by the past couple decades that orcas start going after gray white sharks or they have been going after gray white sharks. And we've seen it in South Africa. We've seen it in other places, but now we're seeing it in Australia. And so I thought this was pretty interesting.
So it was kind of interesting to see the genetic analysis confirmed the presence of orca DNA within a bite room offering direct evidence of predation of these great whites. They also saw some I guess some scavenger sharks that were also had bite marks against the great white sharks. And that was a seven gill shark or a type of seven gill shark, which I thought was pretty interesting. Obviously, these were post death.
And so these bites were just as the shark was dying and probably floating or in the water column. They come in and they grab their flesh and they leave as well. So now previous anecdotal reports and indirect observation suggested that orca predation could lead to behavioral changes in white sharks such as avoidance of a specific area.
This study provides concrete evidence such that interactions happen and which may also have cascading effects in the marine ecosystems like Australia has some big great whites. We know this. This may or may not be the first predation on a great white. We don't know, but it could lead towards movement of these great whites to different areas. We saw this happen in South Africa.
There's still a bit of scientific controversy in that whether it is due to the lack of prey that's in the area for the great whites. So they've actually moved areas or if it's the increase of predation by port and starboard and some South African areas where these great whites are actually just moving away and moving. I think it's more to the east of where they were before. We don't really know for sure, but we do know that they avoid the areas because there's something going on in that area.
There is a good reason to believe that, hey, look, if these orcas are coming in and they're predating and they're getting better at doing it in South Africa, it would usually take two orcas to grab the liver. One would actually hold the great white while the other would rip the area where the liver would be and then actually take out the great white without really destroying the animal. I think killing it, but really ripping the animal apart. They'd be very precise bites.
Then we heard from Dr. Allison Towner on the Beyond Jaws podcast that she has seen one orca actually take out a number of great whites within a few hours. So that this goes to show they're actually getting better and better at killing these great whites. And so the fact that we see some orca predation on great whites in Australia could mean that these great whites are in trouble from a population standpoint from these orcas.
So now this predation event actually raises some interesting questions about the ecological balance between these two predators. It also highlights the importance of understanding predator prey interactions in designing conservation strategies for both species, particularly in regions where human activities and environmental pressures are increasing. So just think about it.
If you have a great whites, which we're at one point and endangered species, they're starting to come back because of specific conservation strategies that would allow their prey to flourish. Like in California, we saw an increase in the great white population because there was an increase in the sea lion population. That was because of the Marine Mound Protection Act.
Now, there was also an increase in the sea lion population, not only because of the Marine Mound Protection Act, but the Magnuson Stevens Act, which is a fisheries act that allowed for more protection on anchovies and sardines, which the sea lions would eat. So having those policies in place allowed not only the prey of the sea lions to flourish, but allowed the sea lions to flourish, which is the prey to the great whites, which allowed the great whites to flourish.
Now there are so many great whites in Southern California. They're starting to move northward or they have moved northward into the San Francisco Bay area in the Monterey area. And now there's like large great white sharks in those areas, adult great white sharks, where the Southern California population are actually juvenile sharks in that area. So it's like a nursery habitat for those great white sharks. This all changes if you have orcas coming in and predating on great whites.
It could shift the balance of specific prey of the great whites. So for instance, if there are seals in the area in Australia, what the great whites are eating, the net seal population could grow, which could affect their prey that would actually reduce their prey and the balance would be all shifted off. I don't know if this is happening. This is all assumptions. But this is what could happen when you have orcas come into an area and wreak havoc on an apex predator population.
So we're going to see some really interesting research come out in the future from these two apex predators. The significance of the study is this is one of the first studies to provide genetic evidence of orca predation on great white sharks. While previous accounts were based on indirect observations, such as scars on sharks or even changes in their presence, this study is definitely proof of direct interaction. So this is one of the studies that says, hey, you know what?
We actually have DNA evidence that orcas have bitten in these areas where they would normally bite in the girdle area where the liver is just behind. Also, these findings contribute to the understanding of predator hierarchy, competition and ecological impacts in marine systems, particularly in regions like South Africa where both species coexist.
There's going to be some really cool things that are coming out of Australia from this research, even South Africa, as we really try to understand that relationship between orcas and great whites as well as other sharks that end up flourishing. So, for instance, in South Africa, when we saw the disappearance of great whites in the Gansby area, we also saw an increase in seven gill sharks in that area because seven gill sharks used to be a prey item of these great whites.
So it's going to be really interesting to see what comes out further. And I can't wait to see what happens. I hope that the balance exists, but this is nature. This is what happens. Now, previously, I said that this is going to be interesting to see how this plays out, especially with human interactions or even environmental pressures that are increasing. So climate change is increasing. Coastal development is increasing. We're seeing fishing pressures increasing.
All these play a dynamic role, not only as individual issues, but also as cumulative issues. And when you manage a population, a lot of populations, fish populations in general, they actually have slowed in their recovery because of outside pressures such as climate change. We don't know how fast a fish population can rebound off a change in population dynamics or predator prey dynamics if there's something else slowing it from actually recovering or actually the same area.
The cod population, for instance, in the northeastern or northwestern Atlantic or northeastern Canada, we have seen cod go from so abundantly available that you can just throw a bucket in like the 1800s and you could actually just grab it with a bucket and you'd grab like two or three fish. Now the cash per unit effort is so high, meaning it's really hard to find cod and there's so much protections on a call that you just can't have a viable commercial fishery like we used to have in the past.
But that was because we let fishing get out of hand. We've been wanting that population to recover and we've seen somewhat of a recovery, but it's taken over 30 years for that recovery to happen. And we're still not seeing it even close to what it used to be in the 70s and 80s where they started to fall down as we started to track those fish stocks. So you just never know what's going to
happen. And a lot of times climate change, more fishing pressures for other fish that can affect the marine ecosystem in the communities that these fish are living in, that cod fish are living in. You just never know what's going to
happen. So having the data, having more research, understanding how each of these issues like climate change, fishing, coastal development, water pollution and marine plastics, all these different types of human issues that will cause a disturbance individually and accumulatively will play a role in the recovery or the change in the population dynamics and the predator prey relationship between orcas and gray whites. It's going to be really interesting to
see how this happens. But of course, you can help by reducing your energy consumption. You can help by reducing your single use plastic usage. You can help a lot of ways eating more sustainable fish or avoiding fish altogether or seafood altogether. There are so many ways that you can help individually. If you want to find out more, you can find out by staying in touch with this podcast.
All you have to do is subscribe to the YouTube channel and hit that notification bell so you don't miss any of the other episodes. You can also hit me up on Spotify, on Apple Podcasts or your favorite podcast app. And if you want to get ahold of me directly, you can DM me on Instagram at how to protect the ocean. But thank you so much for joining me on today's episode of the how to protect the ocean podcast. I had a great time talking to you today. I hope you enjoyed listening. Have a
great day. I'm your host, Andrew Lewin. We'll talk to you next time and happy conservation.